[Electrophoresis and electrofocusing of rhodopsin solubilized by triton X-100]. Detergent-rhodopsin micells (component I) were separated from other fast and slow migrating protein components under electrophoresis of triton X-100 solubilized bovine rod outer segments (ROS). Treatment of ROS by alum caused a complete disappearance of non-rhodopsin proteins and the appearance of slow migrating band (component II). Preliminary bleaching of dark extracts did not affect the migration rate of the component I. The addition of urea to solubilizing mixture caused the increase of component I content and the diffusity components I and II bands. The rate of electrophoretic migration and the content of components I and II sharply decreased together with the appearance of fast migrating pink-brown band after the addition of 2-mercaptoethanol. The extracts from alum-treated ROS were separated into 15-20 protein bands under acrylamide gel isoelectric focusing. Such protein heterogeneity probably depended on the ability of triton X-100 to form micells with different isoelectric points during the interaction with ampholines in the electric field. These micells, having different isoelectric points, are shown to contain one and the same protein--opsin.


[Chlorophyll a and b biosynthesis in the dark in etiolated leaves infiltrated by exogenous chlorophyllide a]. Exogenous chlorophyllide a was introduced into etiolated rye leaves by the vacuum-infiltration technique. Appearance and accumulation of chlorophylls a and b within the leaves are observed during continued darkening, protochlorophyllide photoreduction being avoided. The pigments are identified by the solubility in petroleum ether, paper chromatograms, the fluorescence maxima, the peculiarities of exciting light 430 and 460 nm effects on fluorescence intensity, the specific interaction with hydrochloric hydroxylamine. The conclusion is made that before illumination etioplasts already contain enzyme systems and substrates which provide esterification of chlorophyllide a to chlorophyll a and conversion of chlorophyll a into chlorophyll b.


[Photochemical properties of fucoxanthine]. The ability of fucoxantine for photooxidation by oxygen in a number of organic solvents and for photoreduction by oxorbic acid and phenylhydrazine in pyridine is demonstrated. The reactions are irreversible under common conditions. At the same time fucoxanthine possesses a pronounced ability for photosensitization of red-ox reaction between methyl red and ascorbic acid or phenylhydrazine, which suggests a formation of reversible very labile intermediate pigment compounds at initial steps of photoreaction.


[Rat liver methylation of nuclear DNA following hydrocortisone induction]. After intravenous hydrocortisone injection (2 mg per 100 g of animal weight) DNA methylase activity in rat liver increases 1.5-2 times. Rat liver DNA is capable of being methylated in vitro by homologous and heterologous (from rat spleen and ascite carcinoma cells) enzymes. Rat liver DNA isolated 40 min after hydrocortisone injection contains 1.5 times more 5-methylcytosine and is able to accept 1.5 times less methyl groups from (3H-methyl)-S-adenosylmethionine in the in vitro methylation reaction by enzymes from rat spleen as compared to liver DNA isolated from nontreated rats. Thus, there is DNA supermethylation in rat liver cells occurring under the action of the hormone. This induced change in the methylation level of DNA in rat liver is reversible: 6 hours after a single hydrocortisone injection the amount of 5-methylcytosine in DNA decreases to normal, and the DNA ability to accept methyl groups in the in vitro methylation is the same as compared to that of liver DNA from control animals. The induced reversible DNA methylation is to be considered as a mechanism for the regulation of DNA transcription and cell genetic activity.


[Isolation of phospholipase D from cotton seeds]. A method of isolating homogenous phospholipase D from cotton seeds is described. The homogeneity of the enzyme preparation is demonstrated by means of polyacrylamide disc electrophoresis, gel filtration through Sephadex G-200 and determination of N-terminal amino acid residue, which turned to be glutamic acid. Molecular weight of the enzyme is found to be 71000 +/- 3000. Several equilibrium forms of the enzyme are observed.


[Preparatory extraction of 5'-oligoribonucleotides using ribonuclease from cobra venom]. Cobra (Naja oxiana) venom ribonuclease, which catalyses hydrolysis of polyribonucleotides to 5'-oligonucleotides, was used to obtain preparatively isoplit oligonucleotide fractions, containing 2-30 nucleotides. The yield of hydrolysis products varied depending on the degree of hydrolysis. Hydrolysis rates of different polynucleotides were studied. Hydrolysis rate of polyadenylic acid was 20 times as high as that for polyuridylic acid. Quantitative ratios of isoplit fractions did not vary significantly under similar degree of hydrolysis of polyadenylic and polyuridilic acids. Chromatography on QAE-Sepahdex in ammonium bicarbonate concentration gradient containing 15% dioxan was used to separate enzymatic hydrolysates of polynucleotides, which permitted to bring the fraction isolation to simple evaporation.


[Kinetics of enzymatic hydrolysis of quaternary aminoalkyl esters of aromatic mono- and dicarboxylic acids by butyrylcholinesterase from horse serum]. Enzymatic hydrolysis kinetics of benzoylcholine (BzCh), phehylpropionic acid choline ester (PK-157), suberic acid dicholine ester (D-6) and p-phenylenediacetic (PK-139), p-phenylenedipropionic (PK-154 and PK-155), p-phenylenediacryc (PK-150 and PK-151) and phtalic (PK-105) acids diaminoalkyl esters by horse blood serum butyrylcholinesterase (BuChE) was studied. Hydrolysis constants Km, V and Kss were estimated by means of different graphic methods. PK-157 ester turned to be highly specific selective substrate for BuChE, its V being 20 times as high and Km -- 20 times as low as those for acetylcholine (ACh). The highest V value was found for D-6 in the case of diesters. Hydrolysis of aromatic dicarbonic acids diesters was characterized with significantly lower V values (0.6-10.% of V for ACh) and extremely low Km values (approximately 10(-5) -- 10(-6) M). Substrate inhibition was observed under the hydrolysis of BzCh, PK-157, D-6 and all aromatic dicarbonic acids esters by BuChE. Formal kinetic analysis revealed that inactive complex, which formed in this case, corresponded to ES2 composition. The appearance of substrate inhibition for BuChE and its increasing are supposed to be due to the increase in the size and in the rigidity of the acyl part of the molecule in the number of substrates studied.


[The effect of cycloheximide on incorporation of newly formed mRNA into membrane-bound polyribosomes in rat liver cells]. Incorporation kinetics of new synthesized mRNA into free and endoplasmic membrane-bound polyribosomes in the absence of normal translation (when protein synthesis in inhibited by 98% with cycloheximide) is studied. mRNA is found to incorporate into both free and bound polyribosomes. Relative content of new synthesized membrane-bound polyribosomes in the presence of cycloheximide within 2.5-4.5 hours is by 30-40% lower as compared with the control. This fact can be explained either by the absence of a growing peptide of a sufficient length, which is necessary for the formation of a part of membrane-bound polyribosomes, or by a restricted number of attachment sites on membranes as a result of delayed translation of mRNA in pre-existed polyribosomes. It is suggested that 1) the growing peptide in liver cells is responsible for the recognition of a membrane only under the formation of only one type of membrane-bound polyribosomes, or 2) the formation of all bound polyribosomes has a single mechanism and the growing peptide does not participates in the membrane recognition.


[Changes in rabbit skeletal muscle histone concentration at different periods following denervation]. Dynamics of changes in histone fractions isolated from nuclei of rabbit skeletal muscles after the denervation is investigated by means of ion-exchange chromatography on CM-cellulose and polyacrylamide gel electrophoresis. It is shown that the content of arginine-rich histone fraction F2a1 is significantly increased, and that of lysine-rich histone fraction F1 is decreased on the sixth day after the denervation. Pre-operational injections of actinomycin D prevented these changes. The early suggestion about nervous control of transcription in rabbit skeletal muscles is confirmed.


[Autodegradation of rat liver polyribosomes in vitro]. In vihro decay of rat liver polyribosomes is studied under conditions of occuring phosphorolytic activity of polynucleotidephosphorylase (PNPase) and, in contrast, excluding PNPase activity (in the absence of orthophosphate). The rate of polyribosome degradation is found to be higher in the presence of orthophosphate, than in its absence. Sedimentation coefficient of ribosomes formed from degraded polyribosomes in the absence of orthophosphate is 70S, while that of ribosomes formed under phosphorolysis is 67S. It is suggested that polyribosome degradation in the presence of orthophosphate is carried out by the combined action of 5'-RNase and PNPase. 5'-RNase degrades mRNA and rRNA without disturbing the integrity of ribosomal complexes, while PNPase phosphorolyzes the fragments formed from the 3'-OH terminal, successively releasing ribosomes. The rate of polysome inactivation in the presence of orthophosphate (half-life period being approximately 17 min) is considerably higher than that in the absence of orthophosphate (half-life period being 37 min). The amount of active polysomes in samples incubated for 3 hours both in the presence and in the absence of orthophosphate is 16% and 24% of the total amount of active polysomes, respectively. It is suggested that there are a certain type of polyribosomes, which comprise about 8% of polyribosomes that can be inactivated only by PNPase.


[A kinetic study of the reactive capabilities of xanthine oxidase sulfhydryl groups with regard to n-chlormercuribenzoate]. Kinetic characteristics for reactivity of SH-groups of milk xanthine oxidase were obtained under different conditions. Two types of SH-groups with rate constant values, differing by a factor of about 50, were found in a phosphate buffer at pH 7.0. The slow stage of reaction is followed by protein precipitation. The number of fast- (12) and slowly-reacting (60) groups were calculated from the kinetic data. The blocking of the fast-reacting groups occurs without loss of the enzyme activity. The values of activation energy for the fast- and slowly-reacting groups are 15 and 48 kcal/mol respectively. The formation of the enzyme-substrate complex stabilizes the enzyme molecule; the number of fast-reacting SH-groups and the rate constant values for both types of groups remain unchanged, whereas the number of slowly-reacting SH-groups markedly decreases (37). The values of activation energy for both types of SH-groups show no changes in the presence of substrate. Conformations of the enzyme in different denaturating solvents were characterized by a number of SH-groups, reacting with p-chloromercurybenzoate. 54 groups are exposed in solutions of groups exposed in 7.0-8.5 M urea solutions is 35-38. In all solvents studied the protein molecule is probably not completely unfolded, since the number of exposed SH-groups is less than the full number of SH-groups determined by the amino acid analysis. Only 42 SH-groups reacted with 5,5'-dithiobis-(2-nitrobenzoic acid) under the same conditions.


[Determination of pyrimidine nucleotide sequences of DNA]. A modification of the Burton method for determination of pyrimidine nucleotide blocks (isopliths) of DNA, providing a higher yield of large-sized nucleotide isopliths, is described. The amount of side products (interisopliths) does not exceed their amount upon DNA hydrolysis according to the Burton method. Another advantage of the technique recommended is a considerable shortening of hudrolysis time (20 min instead of 18 hours). The modification described has been successfully used to determine the pyrimidine nucleotide blocks of some warm-blooded animals DNAs. It has been found that the DNA of animals with higher sensitivity to ionised irradiation contains more oligothymidylic sequences as compared to the DNA of animals, less sensitive to irradiation.


[The effect of several 2-alkyl- and 4'-O-methylanalogs of pyridoxol on mouse liver pyridoxal kinase activity]. A simple method of isolation of partially purified puridoxal kinase preparation from mouse liver, having specific activity of 600-700 E/mg protein and a 30% yield is described. It is demonstrated that of all number of 2-alkyl- and 4'-O-methyl pyridoxol analogs synthesized, 4'-O-methyl-pyridoxol (Ki=0.2-10(-5) M, Km(pyridoxal)=4-10(-5) M) is the most active competitive inhibitor of pyridoxal kinase. 3-Deoxy-4'-O-methylpyridoxol is a non-competitive inhibitor of pyridoxal kinase, the latter having an affinity for the enzyme 16 times lower than that of 4'-O-methylpyridoxol. 2-Alkyl analogs of pyridoxol exhibit properties of competitive inhibitors; the affinity of 2'-ethylpyridoxol for the enzyme is 5 times lower than that of 2'-methylpyridoxol; corresponding 2-alkyl derivatives of dimethyl ethers of 3-hydroxycinchomeronic acids have no pronounced affinity for the enzyme. The study of the toxic effects of pyridoxol analogs on the central nervous system has revealed inverse dependence between the neurotoxic dose of the compound and its efficiency as an inhibitor of pyridoxal kinase (Km/Ki value).


[Kinetics of reversible inhibition of cholinesterases by quaternary diaminoalkyl esters of aromatic dicarboxylic acids]. Reversible inhibition of acetylcholinesterase (AChE) from bovine erythrocytes and butyrylcholinesterase (BuChE) from horse blood serum by quaternary diaminoalkyl esters of suberic (D-6), p-phenylenediacetic (PK-139), p-phenylenedipropionic (PK-154 and PK-155), p-phenylenediacrylic (PK-150 and PK-151) and phthalic (PK-105) acids, was studied under the following incubation conditions: pH 7.5, 25 degrees C, 0.1 M KCl. The inhibition kinetics were of a mixed competitive-incompetitive type, the incompetitive component alpha'-having higher values for AChE (0.26-0.60) than for BuChE (0.10-0.20). Diester PK-150 selectively inhibited BuChE (Ki=3.0-10(-6) M); its Ki value for AChE was 4.0-10(-4) M. The other diesters had a stronger inhibitory effect on AChE than on BuChE. High values of alpha' observed during AChE inhibition cannot be interpreted in terms of interaction of those bisquaternary compounds with the anionic site of the acetylated active centre and are probably due to their sorbtion at the peripheral anionic sites. Incompetitive inhibition constants (K'i=Ki/alpha') of BuChE by the diesters PK-139, PK-154 and PK-150 were found to be values of the same order as substrate inhibition constants determined in the course of BuChE hydrolysis of these diesters. Incompetitive inhibition found for the esters studied and substrate inhibition during hydrolysis of these compounds are presumably due to the same mechanism.


[Several properties of cotton seed phospholipase D]. Properties of phospholipase D were studied using purified enzyme preparation from cotton seeds. The results obtained differ from those described in literature. It has been shown that the promoting action is exerted not only by diethyl ether and sodium dodecyl sulfate commonly used as initiators, but by some organic solvents in the presence of calcium ions as well. The activation of phospholipase D is also possible in the presence of other bivalent cations, e.g. Sr2+, Ba2+, Mn2+ and Mg2+. It is assumed that the enzyme activation occurs only in the presence of the stable heterogenous system: water-soluble enzyme--phospholipid--non-aqueous phase. Another important factor is the type of modification of the surface of the phospholipid phase, responsible for the enzyme adsorption and its subsequent activation. Comparison is made of the properties of phospholipases D isolated from cotton seeds and some other sources.


[Intranuclear distribution of rat liver ribosomal RNA]. A method is described for the isolation of pure liver nuclei with minimal cytoplasmic contaminants, loss of nuclear RNA and degradation of nuclear RNA. The RNA components are extracted in three distinct fractions by subsequent treatment with phenol at 4 degrees, 50 degrees and 85 degrees C. The total and 14C-orotate labelled RNA components in the three nuclear RNA fractions are characterized by nucleotide composition, poly(A)-RNA content and agar-gel electrophoresis. The results show that the RNA in three fractions correspond to the nucleosol, nucleolus and chromatin compartments of the nucleus. The nuclear HnRNA components are exclusively in the 85 degrees C RNA. Nuclear ribosomal RNA is extracted in the 4 degrees C and 50 degrees C RNA fractions. These two nuclear RNA fractions are distinct in constituent pre-rRNA species and the rate of labelling of their rRNA components. The amount of the pre-rRNA and rRNA species is determined. The results show that the nucleolus-nucleosol and nucleosol-cytoplasm transitions of ribosomal subparticles are markedly slower processes than the preceeding steps of ribosome biogenesis.


[A proteolytic enzyme bound to the aspartate transaminase of swine heart cytosol]. Purified preparations of aspartate transaminase from pig heart cytosol contain a tightly bound proteolytic enzyme (approximately 2, 5%). The enzyme was separated from aspartate transaminase by gel-filtration on Sephadex G-100 in the presence of sodium dodecyl sulfate and by affinity chromatography on the column with Sepharose, containing covalently bound denaturated aspartate transaminase. Protease has a pH optimum of 9.0 and molecular weight of about 23.000-25.000. The proteolysis rates of different subforms of aspartate transaminase depend on their denaturation lability. A more stable choloenzyme is split at a slower rate than the apoenzyme. An enriched preparation of protease was also shown to split glutamate decarboxylase from E. coli and had no effect on cysteinlyase from hen egg, as well as on lactate dehydrogenase and albumin.


[Substrate specificity of Aspergillus clavatus intracellular acid RNAase]. Substrate specificity of intracellular acid RNAse from Aspergillus clavatus, has been studied using different RNAs, synthetic polynucleotides and diribonucleoside monophosphates as substrates. The enzyme was shown to be a RNAse, non-specific to the chemical nature of bases adjacent to the disrupted phosphodiesther bonds in the molecules of RNA. It has been demonstrated that the order of nucleotide release from RNA coincides with the order of weakening of the enzyme binding to substrates XpY, depending on the base X. Purine bases increase substrates XpY binding with the enzyme and hamper their splitting. The effect of pyrimidine bases on adsorption and catalytic functions of the enzyme is contrary to that of purine bases cited above.


[Interaction of steroid hormones with glutamate dehydrogenase]. The inhibitory action of sex hormones on the glutamate dehydrogenase activity is due to their binding to the enzyme protein. No binding of sex hormones to glutamate dehydrogenase is observed in the presence of L-amino acids, preventing the enzyme dissociation. Under those conditions the enzyme sensitivity to the inhibitory action of the hormones sharply decreases.


[Two forms of pea leaf ferredoxin].

[Two forms of pea leaf ferredoxin]. Some causative factors resulting in the appearance of two components of ferredoxin (Fd) isolated from the pea leaves preparations have been studied by 15% PAG electrophoresis. It has been shown that the composition of the buffer systems (tris-glycine buffer, pH 8,3; veronal buffer, pH 7.0) does not cause Fd separation into two components. Study of the effects of the modifying agents on the active centre and apoprotein of Fd. Showed that the destruction of the active centre does not affect Fd separation and modification of the Fd protein part results in greater amount of the bands on the electrophoregrams. It has been concluded that heterogeneity of Fd is possibly of the genetic nature. The following facts can be regarded as an evidence for existence of both forms of Fd in pea leaves: occurrence of two forms of Fd in chloroplasts isolated in organic media, differing in Fd content during pea ontogenesis and upon varying illumination conditions during their growth.


[A spectrophotometric study of Penicillium brevicompactum RNAase complex formation with adenine nucleotides]. Spectrophotometric study of extracellular Pen. brevicompactum RNAse interaction with adenyl nucleotides and constituents have been carried out. It is states that: 1) complex RNAse--nucleotide is formed by association of one enzyme molecule with one nucleotide molecule; 2) all the nucleotide components base sugar and phosphate, take part in the formation of this complex; 3) for the effective association of this complex it is necessary to have a high correspondence (complementaryty) of nucleotide geometric configuration to the space composition of the active site of RNAse.


[Comparative characteristics of the "ultrasonic" fractions of rabbit leukocyte (neutrophil) and brain chromatin]. Ratios and composition of "ultrasonic" fractions of chromatin in cells with different transcription intensity were studied. The hardly extracted residual fraction of chromatin makes up to about 80% DNA in leukocytes (neutrophils) and about 20% in brain tissue. Comparative characterization of fractions showed that residual DNP of brain and liver include, in addition to fragments of inactive condensed chromatin, the sites actively involved in the synthesis of RNA. The residual DNP of leukocytes, on the contrary, possesses a number of characteristics of inactive chromatin. A hypothesis is discussed of the necessity of close contacts between the most intensively transcribed RNAs and nuclear membrane lipid components, resulting in the incorporation of transcribed sites into the residual fraction.


[Positional distribution of fatty acids in the phospholipids of regenerating rat liver]. The fatty acid composition and positioning in the glycerophospholipids from regenerating rat liver were investigated at different stages of the regeneration process. In the lecithins and phosphatidylethanolamines of the regenerating liver the content of arachidonic acid is lower and that of linoleic acid is higher than in the corresponding lipid fractions of normal rat liver. These deviations are maximal at 24 hours after hepatectomy i.e. at the onset of the mitosis. At any stage of the regeneration the high specifity of the fatty acid positioning characteristical for the normal liver is retained completely. The fatty acid composition of cardiolipin is not changed during the regeneration process.


[The anticoagulant property of a lipoid anticoagulant and the mechanism of its influence on hemocoagulation]. A lipoid anticoagulant (LA) from human brain tissue was shown to possess a higher anticoagulant activity than previously obtained preparations. It has been established that out of four phospholipids present in LA, only phosphatidyl serine inhibits the coagulant activity of plasma. In isolated hemocoagulating systems LA and phosphatidyl serine were shown to inhibit prothrombin conversion catalyzed by thrombokinase and to exert the antithrombic action in the system thrombin--fibrinogen. Kinetic study of phosphatidyl serine- and LA-induced inhibition of thrombine formation and the thrombine--fibrinogen reaction by conjugated inhibition. Similar kinetic behaviour, observed upon inhibition of both processes by phosphatidyl serine and LA suggest that phosphatidyl serine is a main anticoagulant agent of LA.


[The photoelectrochemical effect in solid films of flucoxanthine]. A negative photopotential was shown to appear upon illumination on a fucoxanthin solid film-covered platinum electrode, immersed into an electrolyte solution. The effects of electrolyte pH and the reducing and oxidyzing agents on the photopotential value and its kinetic behaviour upon illumination and in the dark were studied. The data obtained are indicative of the ability of fucoxanthin to perform photochemical reactions at the level of electron transfers, which accounts for its photosensitizing activity.


Amniotic fluid surface tension during pregnancy. A good correlation between the amniotic fluid surface tension and gestational age was found in 51 amniotic fluid samples from normal pregnancies. The samples were obtained between the 20th and 43rd week of gestation. A good relation also exists between amniotic fluid lecithin concentration and fluid surface tension, and between said surface tension and the foam test carried out according to Clements et al. (4).


A micropuncture study of the development of renal function in the young rat. Total kidney function and function of individual surface nephrons were measured under hypotonic saline load conditions in young rats 22-, 30- and 42-days old. The highest values of urine flow rate and GFR were found in 30-day-old rats. The water reabsorption was higher in 42-day-old rats than in two younger groups. This decreased fractional reabsorption of water in younger animals was detectable already in the late proximal tubule and in the early distal tubule. Fractional reabsorption of sodium was significantly lower at the age of 22 and 30 days than at the age of 42 days in both late proximal tubule and in the early distal one.


Changes in the organs of pigs in response to feeding for the first 24 h after birth. III. Fluorescence histochemistry of the carbohydrates of the intestine. The duodenum, jejunum, ileum and large intestine of newborn, and 24-hour-old fed and unfed piglets, and of 10-day-old piglets have been studied by new histochemical methods. At birth Meissner's plexus was most developed in the duodenum. There was little change during the first 24 h, but by 10 days it had become elaborated. Goblet cells were present at birth in all parts of the intestine. After 24 h a large proportion of those in the duodenum had discharged and were being replaced with a new generation. Similar changes took place more slowly in the jejunum and ileum and very much more slowly in the large intestine. Feeding increased the rate of turnover.


Amino acid pools in the feto-maternal system. The determinations of the amino acid pools, including tryptophan (by fluorescence spectrometry), in the arterial and venous blood of the mother, the arterial and venous blood of the fetus (cord blood), the amniotic fluid and the placenta was done in eight women at the moment of delivery. Only nine amino acids (asp, try, met, phe, ser, cys, lys, gly, thr) were significantly retained and four (arg, glu, pro and glu-NH2) were significantly released by the fetal tissues. In contrast with this behavior most amino acids were retained by the maternal tissue, try, phe and hist showing the highest retention. When the amino acids are grouped as essential and nonessentials, the maternal tissues retained both categories without apparent discrimination, while the fetal tissues retained essential amino acids preferentially. Our results emphasize the importance of the placenta as the regulating system of the fetal milieu under normal conditions. Thus human fetal blood levels of amino acids are patterned after the placental ones and not after the maternal values obtained at the same time. It is apparent that the placenta seems to function as a nonspecific retention filter for outgoing amino acids, but that its function is selective in respect to the release of amino acids into the fetal circulation.


Influence of early weaning on the activity of several enzymes in the liver of rat. In normally weaned rats the activity of two enzymes in rat liver, i.e. ATP citrate lyase and malic enzyme, gradually increases between the end of the third and the beginning of the fourth postnatal week. The activity of mitochondrial alpha-glycerophosphate oxidase remains unchanged during this period. Early weaning on the 18th postnatal day causes a rapid increase in activity of these enzymes. The impulse for this increase is very probably the change from high fat milk diet to high carbohydrate standard laboratory diet, the decrease of blood lipids, the activation of thyroid gland and changes of sensitivity of hepatic cells towards thyroid hormones. These results showed that early weaning modifies to the known picture of physiological weaning to a great extent.


The effect of litter size on the growth, survival and behaviour of neonatal bulbectomised mice. Bilateral lesions of the olfactory bulbs in 1-day-old mice led to a slow rate of growth both before and after weaning and the growth changes were positively associated with the size of the lesion. Mothers continued to care for the bulbectomised mice which showed no evidence of retarded motor development though their eyes opened later and they were less active when exposed to an artificial perfume. Bulbectomised mice failed to survive in litters of two where both infants were bulbectomised and in litters with a large number of unoperated littermates. Keeping litters small and having both bulbectomised and control mice present enhanced the chances of survival and the presence of infant control mice is a necessary condition for the maintenance of lactation and the survival of the bulbectomised babies. Failure to respond to the odours( pheromones) of the mothers may be responsible for the infrequent suckling and the slow growth and development.


Triglyceride mobilization in cultured adipocytes of human infants. Cultured adipocytes of human infants, in the absence of known lipolytic agents, are capable of mobilizing their own stored triglycerides as showed by a decrease in the content of stored triglycerides with time. The medium used is synthetic, fortified with 20% fetal calf serum and contains adequate amount of glucose. It is suggested that lipolysis occurs because the metabolic balance favors lipolysis in the absence of adequate amount of free fatty acids in the medium. Conversely lipogenesis is favored in the presence of such fatty acids.


Post-natal development of factor II (pre-prothrombin and prothrombin) in man. Postnatal development of factor II molecule has been evaluated by three different methods in infants and children from 15 days to 7 years of age. The immunochemical determination of factor II showed that the plasma levels of this factor reached the lowest adult values between 4-7 months of age and rose slowly for all the first year; after this age the plasma concentration was steady. The adult range was reached from 15 to 120 days of age when the factor II was evaluated by the method of Owren and Aas (19) and by staphylocoagulase reagent.


Sex differences in patterns of EEG asymmetry. This paper reports three studies showing sex differences in EEG asymmetry during self-generated cognitive and affective tasks. In the first experiment, bilateral EEG, quantified for alpha on-line, was recorded from right-handed subjects while they either whistled, sang or recited lyrics of familiar songs. The results revealed significant asymmetry between the whistle and talk conditions only for subjects with no familial left-handedness and, within this group, only for females and not for males. In the second experiment, bilateral EEG was recorded while right-handed subjects (with no familial left-handedness) self-induced covert affective and non-affective states. Results revealed significantly greater relative right-hemisphere activation during emotion versus non-emotion trials only in females; males showed no significant task-dependent shifts in asymmetry between conditions. The third experiment was designed to test the hypothesis that females show greater percent time asymmetry than males during biofeedback training for symmetrical and asymmetrical EEG patterns. Results confirmed this prediction as well as indicating that females show better control of such asymmetrical cortical patterning. These findings provide new neuropsychological support for the hypothesis of greater bilateral flexibility in females during self-generation tasks.


Effects of warning-signal modality on the contingent negative variation (CNV). CNVs were recorded during the S1-S2 interval of a prolonged simple reaction task. In the task, a warning stimulus S1 is followed by an imperative stimulus S2, to which the subject makes a motor response. The differential effects of a visual and an auditory S1 were investigated under two interstimulus interval (ISI) durations (1 and 3 sec). Under the 3 sec ISI condition, the form of the slow negative wave demonstrated clearly a biphasic character: an orientation wave (O wave) following S1 with a peak latency at about 650 msec and an expectancy wave (E wave), which reaches its largest amplitude towards the end of the ISI. Under the 1 sec ISI condition the two components of the CNV are confounded. The O wave had a fronto-central distribution, while the E wave was located precentrally. The O wave was enhanced after an auditory S1, as compared to a visual S1.


The effects of controlled muscle tension on performance and learning of heart-rate control. Thirty female subjects were divided in three groups and instructed in group I to increase their HRs with the aid of continuous feedback of performance, while they tensed their right forearm muscles 20% of maximal voluntary contraction. In the last session only feedback was used, Group II were trained with feedback only. Group III for the first two sessions tensed their muscles only, and in the last session trained HR increases with feedback only. Group I was superior in HR performance in the first two sessions. In the third session they deteriorated significantly and could not be distinguished from the other two groups. The results were interpreted in terms of relations between somatic and autonomic events and transfer between different states of somatic involvement during learning. Electrodermal activity and respiration were included as control variables.


Heart-rate decelerative Pavlovian conditioning with tilt as UCS: towards behavioural control of cardiac dysfunction. As part of a programme the ultimate goal of which is to teach behavioural control of stress-induced maladaptive cardiac accelerations through Pavlovian decelerative conditioning, this study was directed at examining the feasibility of using tilting of the body from a head-up to a head-down position as the unconditional stimulus (UCS) to elicit phasic cardiac deceleration as the unconditional response (UCR). Experiment I assessed the reflexive features of the cardiac response to 32 tilt UCS trials delivered at mean intervals of 75 sec. The results yielded a large-magnitude (over 30 BsPM) cardiac decelerative UCR with fast recruitment and complete resistance to habituation. Experiment II examined the feasibility of using the tilt UCS to demonstrate associative control over decelerative responding to a tone as the conditional stimulus (CS). Relative to a control 'backward' UCS-CS group with an interstimulus interval (ISI) of 14.5 sec, a 0.5 sec ISI CS-UCS experimental group demonstrated both orderly acquisition and extinction performance. The magnitude of the conditional deceleration of some 4 BsPM is greater than the extent of control generally achieved with biofeedback, but still constitutes a problem for theoretical accounts of classical conditioning framed in terms of stimulus substitution, and is still only of borderline clinical significance.


Shear-induced hemolysis: effects of blood chemistry (including aging in storage) and shearing surfaces. Rotating disks were used to hemolyze blood under low-stress laminar flow conditions. In the first sequence of tests, kinetic hemolysis curves (KHC) were obtained with polyethylene disks for three well-characterized bloods and repeated over a period of four weeks. Each blood had a KHC with different shape, which maintained its characteristics while aging. Correlations were sought between D6000 (percent of complete hemolysis, after 6000 sec of shear) and D0 (measured before shear) by two means of data analysis, in terms of blood chemistry. It was found that uric acid and very-low-density lipoprotein levels were most useful in predicting the characteristic D6000 vs. D0 relation for each blood, and that glucose levels correlated the rate of aging as measured by hemolysis. Other chemical factors are also displayed in terms of their influence on D0. The second series of tests consisted of comparing the KHC for four disk materials using a fourth blood, then repeating with a fifth blood. Hemolytic rankings of the materials were the same with these two blood, although the KHC shapes differed. The rankings were: polyvinyl chloride greater than Silastic approximately equal to polyethylene greater than polyether urethane, with PVC most hemolytic. In another sequence for examining materials effects, five different bloods were used to compare the hemolytic properties of Teflon, nylon, and polyethylene disks. Although the KHC for the three disks bore different relationships to each other with each different blood, extrapolation of data beyond 6000 sec suggests a ranking of Teflon greater than nylon greater than polyethylene.


Intra-uterine devices, A SEM study on the Dalkon Shield. A SEM study carried on intra-uterine devices (Dalkon Shield) is reported. The poor manufacturing of the devices is stressed, which could increase their efficiency but also the risks of penetration, or worse, perforation. The solution for the future could be copper bearing intra-uterine devices coated by hydrogels. This should maintain efficiency and improve security.


Home care: a biomedical engineering challenge. The contributions of biomedical engineering to health care delivery have focused on techniques for acquiring and processing patient data, primarily in the high technology setting of modern hospitals. The increased sophistication of hospitals is responsible in large measure for the soaring costs of health care. The current trend toward both ambulatory and home care provides new and challenging opportunities for biomedical engineering to bear on problems of great social and economic consequence in facilitating safe and effective care of the chronically ill in the security and comfort of their own homes. Techniques which are refined for use by the expanding population of both aged and handicapped individuals are also of potential value for the home care of younger patients with broader life expectancy. Projections into the future prospects for home care elicit a wide diversity of opportunities of great significance to the future of the health professions and society as a whole.


Ultrasonic assessment of early callus formation. A 0.5 MHz pulse-transmission ultrasonic device is described and results obtained with an animal model presented. Two waveform components have been identified which correlate with the healing process. The "bone wave" is indicative of endosteal callus formation and the strength of cortical union. The "callus wave" is indicative of early periosteal callus formation. Recordings are presented to demonstrate the nature of the in vivo recordings, and the changes seen during the early stages of healing. In vitro recordings are presented to demonstrate that the signals are indicative of the properties of the bone and fracture, and are not soft tissue artifacts.


A system for rapid analysis of long-term recordings of heart rate and other physiological parameters. Using miniature cassette tape recorders, measurement of ECG and other physiological measures is possible in industrial or working situations. The development of a semi-automatic high speed processing system for analysis of the tape recorded data is described. This system decodes the signals on the tape, converts ECG to heart rate and presents a listing of the heart rate variation over the recording period, which may be up to 24 hours. A punched paper tape copy of the listing is used for input into a mainframe computer for subsequent analysis. The recorders and processing system have been used extensively for three years on a study of industrial work stress, and have proved reliable, accurate, and of sufficient sensitivity for in-depth analysis. They allow considerable data to be collected, permitting the thorough statistical analysis necessary for the interpretation of complex physiological responses.


Microprocessors in health care: panacea or more effervescent technology? The impact of microprocessors on medical instrumentation is explored, with particular reference to their role within a health care system that has finite resources. The authors present two examples of microprocessor use from their own experience and attempt to highlight both the merits and the disadvantages of the use of such technology by the hospital medical engineer.


A bioengineering analysis of force actions at the knee in normal and pathological gait. The paper describes a simplified bioengineering analysis for the determination of force actions at the knee joint for normal and pathological gaits. The stance phase of the gait cycle only is considered, and gravitational and inertia forces are excluded from the analysis. The anatomical and functional assumptions required for analysis are discussed. Force actions transmitted at the knee joint by the bearing surfaces, muscles and ligaments for normal individuals are presented with reference to magnitude and phasic relationship for the activity of level walking. Bearing loads transmitted at the knee joints of pathological limbs are also discussed.


Development of a valve for internal drainage of ascites into the venous system. A valve for transfer of ascites into the inferior vena caval system, has been developed. The valve answers the specific problems of this pathological condition, namely chemical composition and quantity of fluid and pressure gradient. The valve has been used in preliminary experiments carried out on dogs. The results obtained were encouraging.


A calibration system for catheter transducer pressure measurement. A patient-isolated calibration system is described for use with catheter transducer physiological pressure measuring apparatus. A subatmospheric calibration pressure is applied to the rear of the transducer diaphragm, the latter isolating the patient hydraulic circuit from the calibration system. The calibration system need not therefore be sterile and remains assembled to the transducer table. Risk of air embolus in the patient and of over-pressurising the transducer during calibration are minimised. Simplification of the hydraulic circuit reduces the chance of air entrapment, improving frequency response and reproducability of results and preparation time is greatly reduced. The system is easy to make and has proved simple, rugged and reliable in use.


Data analysis problems in the area of pharmacokinetics research. Of interest in compartment analysis is the estimation of kinetic first order rate constants and quantification of the amount of drug present in each compartment at every point in time. From the data pertaining to only one compartment, it is not always possible to estimate all the first order rate parameters of linear and non-linear compartment systems. When multiple varying doses are administered at different intervals of time, the equations quantifying the maximum and minimum amount of drug accumulated in each interval may be used. To obtain estimates of kinetic parameters, statistical adjustments may be used in the kinetic equations.


Estimating mean time to reach a milestone, using retrospective data. In surveys to estimate the mean age at menarche (or another milestone reached by the whole population), interviewed girls in the age range can respond that menarche (a) has not occurred or (b) has occurred or (c) occurred at a certain age t. Answers of type (a) and (b) are called status quo data. Answers of type (a) and (c) are called retrospective data.One kind of data is assumed. The distribution of age at menarche may also be assumed to be normal or not necessarily normal. This gives four possible sets of assumptions. Estimators, with their asymptotic distributions and optimal sampling allocations, are found for the case of retrospective data and non-normal distribution. These estimators are compared in examples with previously proposed estimators based on the other sets of assumptions. In these examples, retrospective data should certainly be used if available and reliable.


An exact test of the Hardy-Weinberg law. An exact distribution of a finite sample drawn from an infinite population in Hardy-Weinberg Equilibrium is described for k-alleles. Accordingly, an exact test of the law is presented and compared with two x2-tests for two and three alleles. For two alleles, it is shown that the "classical" c2-test is very adequate for sample sizes as small as ten. For three alleles, it is shown that a simpler formulation based on Leven's distribution approximates the exact test of this paper rather closely. However, it is recommended that researchers continue to employ the standard x2-test for all sample sizes and abide by it if the corresponding probability value is not "too close" to the critical level; otherwise, an exact test should be used.


Parameter estimation in studying circadian rhythms. In the model under consideration for the circadian rhythm study there are three unknown physiological parameters involved: the level, the amplitude and the phase. This paper concerns the estimation of the group level, group amplitude and group phase of a certain group of individuals based on their time series data. Special attention is paid to the amplitude and phase parameters, and solutions are obtained for both the small-sample and the large-sample cases.


[The influence of glucagon on post-heparin plasma lipolytic activity in normal rats and in rats with diabetes induced by alloxan injection]. The authors compared the effect of glucagon on the post-heparinic lipolytic activity in normal and alloxan induced diabetic rats. Within their experimental conditions, it was considered that an injury of the cell stimulates a decrease of the glucagon-stimulating activity on the lipoprotein lipase: this hormone does not seem to have a direct action on the PHLA but an indirect one by the way of the insulin secretion it induces.


[Perfecting of a technic for the in vivo study of intestinal absorption of monosaccharides in rats]. A method for in vivo perfusion of isolated jejunal and ileal loops with catheterisation of the efferent veins is described in the rat. The haemodynamical, histological results and the steadiness of D-glucose absorption showed that there functional ability was preserved at least during one hour. D-glucose is absorbed faster by the jejunal than the ileal portion in the rat.


[The geography of leukemias and hematosarcomas]. The geography of leukemias and haematosarcomas is comprised of two parts 1) The study of geographic lymphomas, Burkitt tumor, and alpha heavy chain disease. 2) The general geography of leukemias and haematosarcomas a) leukemias: variations of frequency according to the country, variations of the frequency of different forms of leukemia, temporal variations b) haematosarcomas, increased frequency in hot countries, unequal distribution of Hodgkin's disease in children and adults. Geography of animal and human leukemias. First description of "ethnologic hematology".


A study of protoplasmic streaming in Nitella by laser Doppler spectroscopy. Laser light scattered from particles in the streaming protoplasm of a living cell is shifted in frequency by the Doppler effect. The spectrum of the scattered light can be measured and interpreted to infer details of the velocity distribution in the protoplasm. We have developed this approach to study the protoplasmic streaming in the fresh-water alga Nitella. Our results indicate a characteristic flow pattern to which diffusion makes a negligible contribution. No difference in the velocity of particles of different size is indicated. The streaming velocity linearly with temperature with a supraoptimal temperature of 34 degrees C, and the velocity distribution becomes narrower at high temperatures. The protoplasmic streaming can be inhibited by laser light, and this effect has been used to study the photoresponse of the algae. Using beam diameters of about 50 mum, we have shown that the inhibition is very local, becoming minimal at a displacement of about 200 mum in the upstream direction and 400 mum in the downstream direction. Prolonged exposure produces a bleached area free of chloroplasts, which is three orders of magnitude less sensitive to photoinhibition.


Distribution of bacteria in the velocity gradient centrifuge. Cells in different parts of the cell cycle can be separated by brief centrifugation in a density stabilized gradient: the Mitchison-Vincent technique. The position of a cell in the tube depends upon its size, shape, and density, upon the gradients of density, viscosity, and centrifugal force through which it sediments, and upon time. A program to compute the velocities and integrate the velocity profile for particles of a particular size class is presented. Because enteric bacteria are a form intermediate between right cylinders and prolate ellipsoids of revolution, the program uses values for the frictional coefficient intermediate between those calculated for ellipsoids and for cylinders. The formula f=6pietab(a/b)1/2 possesses this property and because of its simplicity greatly speeds the calculations. A second program computes the distribution of masses and then of sedimentation constants for a bacterial population, expressed either as a frequency distribution or as total mass per s-class. The effect of the known variation in cell size at division is included in these calculations, which apply to organisms undergoing balanced, asynchronous growth in which mass increase is proportional to cell size. The two programs in conjunction compute the mass or cell-number profile in an arbitrary gradient. The programs have been used to design gradients to maximize the resolution of the technique.


A diffusion driven instability in systems that separate particles by velocity sedimentation. Velocity sedimentation has been used extensively to separate particles according to the magnitude of their sedimentation velocity in suitable media. This technique has been used over a wide range of particle size from protein molecules, viruses, subcellular particles to whole cells. Successful separation demands that collective particle motion should not occur. In practice it is observed that such systems may, under certain circumstances, suffer from a particular type of instability which destroys the normal dependence of sedimentation velocity on particle size and density. The aim of this paper is to identify the critical parameters that determine the development of this instability. Stability criteria are deduced and predictions of the theory compared with published observations. Satisfactory agreement between theory and observation is obtained. It is concluded that the simple stability criterion, namely that stable sedimentation will occur if the total density gradient is in the direction of the sedimenting force, grossly overestimates the particle load that can be separated in practice. Some specific recommendations for optimum particle loading are included. Earlier theoretical and experimental works are briefly reviewed.


Absence of biomagnetic effects in Nitella. The ability of N. flexilis and N. translucens to survive exposure to magnetic fields up to 1.6 T for extended periods of time was tested. Internodal cells subjected to such fields for as long as 72 h showed no evidence of damage. The active response of internodal cells was studied using an especially constructed sample chamber which allowed the use of intracellular microelectrodes. Action potentials in longitudinal and transverse fields as large as 2.0 T appeared identical to those in zero field. The results are in sharp contrast to observations reported by Arajs et al. (1975, Proceedings of the International Conference on Magnetism and Magnetic Materials).


Temperature dependency of the rate of electron transport as a monitor of protein motion. The temperature dependency of the rate of biological electron transport is interpreted as evolving from a contraction of the electron transport components. A theoretical expression for this temperature dependency is derived in terms of the coefficient of linear expansion (a) of the protein components. Using this expression alpha is calculated for several electron transport systems and shown to be similar to alpha-values of synthetic polymers. A discontinuity in alpha is shown to be present in all biological electron transport reactions at ca. 150 K. This discontinuity is interpreted as a change in the intramolecular bonding of the electron transport protein units.


Formation of planar bilayer membranes from lipid monolayers. A critique. The formation of planar bilayer membranes from lipid monolayers as described by Montal and Mueller (Proc. Natl. Acad. Sci. 1972. 69:3561) is analyzed. Bilayers absolutely free of alkane solvents or other nonpolar hydrocarbons can be formed on polytetrafluoroethylene (PTFE) (e.g. Teflon) septa only if certain boundary conditions are satisfied. Measurements have been made of the contact angles between monolayer-coated water and PTFE in the presence and absence of alkane solvents. The measurement suggest that the boundary conditions for formation of stable bilayers can be satisfied only when a nonpolar solvent is present. We conclude that the bilayer must be surrounded by a torus of alkane solvent, petroleum jelly, or silicone grease depending upon the details of technique used to form the bilayer. The non-polar solvent used in the formation of the bilayer may or may not be present in the bilayer depending upon the water solubility and size of the solvent molecule relative to the size of the alkyl chain of the lipid. Detailed sketches describing the formation of bilayers from monolayers are presented.


Phase determination of x-ray reflections for membrane-type systems with constant fluid density. A new technique for phase determination of X-ray reflections from symmetric structures is presented. This method, involving comparison of intensity data from structures with variable fluid layer thickness and constant fluid electron density, permits computation of phase angles, scaling factors, and origin reflection values independently. Possible sources of error inherent in other methods of phase determination are thereby eliminated. Results of the application of this method to model structures and to myelin data are reported. Advantages of the technique, which tests all possible phase angle combinations in a rapid fashion, are discussed.


Effects of ultraviolet irradiation on the rate and sequence of DNA replication in synchronized Chinese hamster cells. The effects of ultraviolet light (UV) irradiation on the rate of DNA replication in synchronized Chinese hamster ovary (CHO) cells were investigated. A technique for measuring semiconservative DNA replication was employed that involved growing the cells in medium containing 5-bromodeoxyuridine and subsequently determining the amount of DNA that acquired hybrid buoyant density in CsCl density gradients. One of the advantages of this technique was that it allowed a characterization of the extent of DNA replication as well as rate after irradiation. It was found that while there was a dose-dependent reduction in the rate of DNA replication following UV-irradiation, doses of up to 10 J/m2 (which produce many dimers per replication) did not prevent the ultimate replication of the entire genome. Hence, we conclude that dimers cannot be absolute blocks to DNA replication. In order to account for the total genome replication observed, a mechanism must exist that allows genome replication between dimers. The degree of reduction in the rate of replication by UV was the same whether the cells were irradiated at the G1-S boundary or 1 h into S-phase. Previous work had shown that cells in early S-phase are considerably more sensitive to UV than cells at the G1-S boundary. Experiments specifically designed to test for reiterative replication showed that UV does not induce a second round of DNA replication within the same S-phase.


A possible mechanism for concentrating sodium and potassium in the cell nucleus. A dynamic, nonequilibrium mechanism is proposed for concentrating both Na+ and K+ in the cell nucleus. The model is consistent with experiment observations and with known properties of cell membranes. This model could explaing the high nucleoplasm to cytoplasm ratios of Na+ and/or K+ reported for liver kidney, thymus, frog skin, ascites cells, and amphibian oocytes.


Application of splines to the calculation of bacterial swimming speed distributions. A new method of extracting information about bacterial speeds from photon correlation spectroscopy is presented. This method has the advantage that an estimation of the translational speed distribution is directly varied so as to achieve a best least-squares fit to the experimental autocorrelation function. The theory of spline approximations to continuous functions is briefly outlined. The importance of the previously disregarded diffusional component of bacterial motion is discussed. Experimental data from Salmonella at a low scattering angle is analyzed by this method of spline approximation and the distribution of translational speeds is obtained.


Picosecond kinetics of the fluorescence from the chromophore of the purple membrane protein of Halobacterium halobium. The fluorescence emission kinetics at 740 nm of the retinylidence chromophore of the purple membrane protein of Halobacterium halobium have been studied. Using picosecond laser pulses and an optical Kerr gate, the fluorescence risetime is found to be less than 8 ps and its lifetime is 40 +/- 5 ps at 90 degrees K and is estimated to be less than 3 ps at room temperature.


Effect of a phase transition on the binding of 1-anilino-8-naphthalenesulfonate to phospholipid membranes. The binding of 1-anilino-8-naphthalenesulfonate (ANS) to dipalmitoyl-phosphatidycholine (DPPC)-sonicated vesicles was measured by a fluorimetric method in the vicinity of the gel-to-liquid crystalline phase transition temperature (Tm). A similar measurement was performed on large multimellar DPPC vesicles through equilibrium dialysis. Both measurements demonstrated anomalous dye binding in the temperature region of the Tm and slightly above (prefreezing region). The amount of ANS bound at this temperature region was in excess of what would be expected based on extrapolation of the high temperature binding data; just below the Tm, the amount of bound dye decreased abruptly. The fluorimetric studies on vesicles also indicated that inner monolayer binding of ANS was markedly inhibited below the Tm. The possibility that the increase in bound dye in the prefreezing region was caused by enhanced lateral compressibility, density fluctuations, or additional binding sites at the boundary of transient gel-like clusters is discussed and the general topic of anomalous increases in various membrane processes in the vicinity of a phase transition is briefly reviewed.


Heat transfer from spheres and other animal forms. A general predictive relation for the convection heat transfer from animal forms is developed. This relation is based on the convection equation for a sphere, and employs a simple, unique characteristic dimension to represent the animal which is the cube root of the animal volume. The accuracy of this relation is established through comparison with available convection results from animal shapes ranging in size and shape from spiders to cows. This relation allows an extrapolation to animal shapes for which data are not available. Results are also presented for the enhancement of convection heat transfer due to natural turbulence. A procedure is outlined for estimating the convecture heat loss from an animal in the natural outdoor environment.


Elastic area compressibility modulus of red cell membrane. Micropipette measurements of isotropic tension vs. area expansion in pre-swollen single human red cells gave a value of 288 +/- 50 SD dyn/cm for the elastic, area compressibility modulus of the total membrane at 25 degrees C. This elastic constant, characterizing the resistance to area expansion or compression, is about 4 X 10(4) times greater than the elastic modulus for shear rigidity; therefore, in situations where deformation of the membrane does not require large isotropic tensions (e.g., in passage through normal capillaries), the membrane can be treated by a simple constitutive relation for a two-dimensionally, incompressible material (i.e. fixed area). The tension was found to be linear and reversible for the range of area changes observed (within the experimental system resolution of 10%). The maximum fractional area expansion required to produce lysis was uniformly distributed between 2 and 4% with 3% average and 0.7% SD. By heating the cells to 50 degrees C, it appears that the structural matrix (responsible for the shear rigidity and most of the strength in isotropic tension) is disrupted and primarily the lipid bilayer resists lysis. Therefore, the relative contributions of the structural matrix and lipid bilayer to the elastic, area compressibility could be estimated. The maximum isotropic tension at 25 degrees C is 10-12 dyn/cm and at 50 degrees C is between 3 and 4 dyn/cm. From this data, the respective compressibilities are estimated at 193 dyn/cm and 95 dyn/cm for structural network and bilayer. The latter value correlates well with data on in vitro, monolayer surface pressure versus area curves at oil-water interfaces.


Constitutive relation for red cell membrane. Correction. The intention of this note is to correct a subtle and somewhat esoteric error that the author discovered in his previous publications on membrane elastic behavior. The consitutive relation between membrane force resultants and large, elastic deformations of a membrane surface involves a strain tensor, characterizing the finite deformations. The original strain tensor that appeared in the equations was the Lagrangian strain tensor; however, the proper strain representation (also Lagrangian in nature because it is "measured" relative to the undeformed material state) is transformed by rotations of coordinates in the deformed material state (whereas the Lagrangian strain tensor is transformed by rotations of coordinates in the undeformed state). The principal membrane tensions are unchanged by this correction; the material elastic constants remain the same; and therefore, the material behavior in shear and isotropic tension is the same. However, the tensor, constitutive relation can be properly applied to coordinate systems other than the principal axis system.


Analysis of freeze-fracture electron micrographs by a computer-based technique. A procedure is described for deriving a numerical characterization of membrane particle patterns revealed in freeze-fracture electron micrographs. Rectangular coordinates of the particles are obtained with high precision by means of an electronic digitizing device. These coordinates are fed into a large computer and analyzed in terms of (alpha) a local particle density function in terms of variable subdivisions of the membrane, and (beta) an interparticle distance function describing describing all particle pairs within the membrane. It is found that the particle density function gives the most useful description of clustering provided that particle-free patches are monitored along with nonvanishing particle densities. Theoretical particle patterns are generated with the computer by means of a random number generator to provide defined aggregation states which serve as standards of comparison for observed particle patterns.


Action currents, internodal potentials, and extracellular records of myelinated mammalian nerve fibers derived from node potentials. The potential distribution within the internodal axon of mammalian nerve fibers is derived by applying known node potential waveforms to the ends of an equivalent circuit model of the internode. The complete spatial/temporal profile of action potentials synthesized from the internodal profiles is used to compute the node current waveforn, and the extracellular action potential around fibers captured within a tubular electrode. For amphibia, the results agreed with empirical values. For mammals, the amplitude of the node currents plotted against conduction velocity was fitted by a straight line. The extracellular potential waveform depended on the location of the nodes within the tube. For tubes of length from 2 to 8 internodes, extracellular wave amplitude (mammals) was about one-third of the product of peak node current and tube resistance (center to ends). The extracellular potentials developed by longitudinal and radial currents in an anisotropic medium (fiber bundle) are compared.


Experimental measurement of the stiffness of the cupula. An experimental procedure is described which consists of cutting the canal duct, inserting a micropipette and administering known volumetric displacements to the cupula. The cupula is made visible by dying the endolymph. Known displacements are administered to the cupula, and the time constant of the return to its equilibrium position is measured. With this information, the stiffness of the cupula is calculated. The experiment was successfully carried out on five White King pigeons. The mean stiffness found in somewhat less than other results reported in the literature, and reasons for this discrepancy are noted.


Liquid membrane potential in nonisothermal systems. Electrical membrane potential equations for liquid ion exchange membranes, characterized by the presence of uncharged associated species and by exclusion of co-ions (no electrolyte uptake) have been derived. The irreversible thermodynamic theories already developed for solid membranes with fixed charged site density have been extended to include the different physicochemical aspects of the liquid membranes. To this purpose the dissipation function has been written with reference to the fluxes of all the species present in the membrane. It has been found that the mobile charged site, the counterions, and the uncharged associated species contribute to the electrical membrane potential through their phenomenological coefficients. The electrical membrane potential equations have been integrated in isothermal and nonisothermal conditions for monoionic and biionic systems. The theoretical predictions have been experimentally tested by studying the electrical potential of liquid membranes formed with solutions of tetraheptylammonium salts in  omicron-dichlorobenzene.


The kinetics of cholesterol oxidase synthesis by Nocardia rhodocrous. The production of cholesterol oxidase by 3 liter batch cultures of Nocardia rhodocrous growing on a glycerol/yeast extract medium was investigated. Cholesterol was shown to be a good inducer of the enzyme. The optimum time for cholesterol addition and the quantity to be added were determined, resulting in a 15-fold yield increase. Cholesterol oxidase synthesis was influenced by the dissolved oxygen tension. Maximum cholesterol oxidase production was obtained at 30-40% air saturation. The effect of growth conditions on the extraction of cholesterol oxidase by Triton X-100 was investigated. The scale-up of the fermentation to 800 liters in a pilot-plant fermenter is described.


A model for enzymatic isomerization of D-glucose to D-fructose in a batch reactor. Using whole cells containing glucose isomerase, mathematical models for the enzymatic conversion of D-glucose to D-fructose and for the inactivation of the enzyme catalyst have been postulated and verified experimentally. The heat of reaction, the equilibrium constant, and the individual rate constants and their activation energies have been estimated. The model can be used to predict the time course for the enzymatic production of fructose in a batch reactor within the tested experimental range of 40-80 degrees C.


Effects of immobilization on the kinetics of enzyme-catalyzed reactions. I. Glucose oxidase in a recirculation reactor system. Glucose oxidase from Aspergillus niger was immobilized on nonporous glass beads by covalent bonding and its kinetics were studied in a packed-column recycle reactor. The optimum pH of the immobilized enzyme was the same as that of soluble enzyme; however, immobilized glucose oxidase showed a sharper pH-activity profile than that of the soluble enzyme. The kinetic behavior of immobilized glucose oxidase at optimum pH and 25 degrees C was similar to that of the soluble enzyme, but the immobilized material showed increased temperature sensitivity. Immobilized glucose oxidase showed no loss in activity on storage at 4 degrees C for nearly ten weeks. On continuous use for 60 hr, the immobilized enzyme showed about a 40% loss in activity but no change in the kinetic constant.


Effects of immobilization on the kinetics of enzyme-catalyzed reactions. II. Urease in a packed-column differential reactor system. Urease from Jack bean was immobilized on nonporous glass beads by covalent bonding and its kinetics were studied in a packed-column differential reactor. To facilitate comparison, the urease was immobilized by both diazo and glutaraldehyde coupling. The kinetic properties of immobilized urease were similar to those of the soluble enzyme and different immobilization methods did not appreciably alter the kinetic properties. The affects of three different amino acid activators appear to follow predictions obtained from a relatively simple competitive model, except at very low substrate levels.


[A histochemical study of the distribution of plasminogen activator in myocardial tissue in experimental ischemia]. The level of plasminogen activator activity studied by histochemical method in the myocardial tissue of rats during experimental ischemia was decreased if compared with control animals. The maximal decrease was seen the next day after the occlusion of the coronary artery, particularly in the necrotic zone. Plasminogen activator activity level began to increase in 3 days. Histochemical data were confirmed biochemically.


[The influence of several surface-active substances on neuromuscular transmission of excitation]. Microelectrode method was applied to the study of the influence of sodium bile salts (BS), saponin and between-80 on the end-plate potentials (EPP) of m. sartorius of Rana ridibunda. Bile salts in a concentration of 10(-5) g/ml did not change these potentials significantly. With increase of the BS concentration up to 10(-4) g/ml the amplitude of EPP increased 1.5- 3 times. The action of these substances in a concentration up to 10(-3) g/ml caused similar, but more rapid, increase in the EPP amplitude, and then the amplitude decreased. Saponin and tween-80 were less efffective in their action on EPP, but evoked muscle contraction. It is suggested that an increase in the EPP amplitude as a result of the action of the mentioned agents was chiefly connected with stimulation of the acetylcholine release by the nerve terminals.


[Elastic properties of the atria and characteristics of atrial mechanoreceptors]. Acute experiments were conducted on cats; a recording was made of the sum total activity of the mechanoreceptors of the right auricle, pressure in the auricle and its extension. It was demonstrated that extensibility of the auricles sharpely decreased with the pressure of over 5mm Hg, whereas with high pressure there was seen a marked increase in the sensitivity of the mechanoreceptors to the auricular extension. Due to this linear relationship between the pressure in the auricle and the activity of the mechanoreceptors was etained this permitting them to supply information to the rcentral nervous system concerning the auricular pressur with its change within a wide range.


[Experimental vestibulopathy produced as a result of formation of a generator of pathologically enhanced excitation in the vestibular nuclei (phenomenon of a determinative dispatch station)]. A possibility of formation of a generator of pathologically enhanced excitation in the system of the vestibular nuclei of the medulla oblongata by disturbance of their inhibitory processes (resulting in development of contralateral rotatory motions in animals) was shown. Experiments with electrical stimulation of the lateral vestibular nucleus and its coagulation showed the system of the vestibular neurons organizing the synchronous message by the vestibulo-spinal pathways to underlie the generator of the pathologically enhanced excitation. It was concluded that the generator of the pathologically enhanced excitation formed in the lateral vestibular nucleus as a result of disturbed inhibition underlied the hyperactive determinative dispatch station causing the syndrome of vestibulopathy


[Dynamics of the responsiveness of the mesenteric microvessels of rats with experimental renal and hormonal hypertension]. Reactivity of mesenteric arterioles (10- 30 mu in diameter) was studied in vivo after the application of histamine 100- 500 gamma), adrenaline, noradrenaline, and acetylcholine (1- 10 mug) in normal rats and in the animals with renal and hormonal hypertension. Sensitivity of microvessels to the action of vasoactive substances proved to change depending on the stage of hypertension.


[External respiration and the functional state of the respiratory center in hypoxia developing against a background of inactivated carbonic anhydrase]. Experiments were conducted on cats; inactivation of carboanhydrase with diamox prevented developmento f hypocapnia and disturbances of the rhythmic activity of the respiratory neurons associated with it in acute hypoxia. However, comparision of electrophysiological data, external respiration indices, of the acid-base balance, pO2 and pCO2 of arterial blood demonstrated that, preventing development of pathological Cheyne-Stokes respiration under conditions of hypoxia, inactivation of carboanhydrase with diamox caused dissociation of the thoracic and abdominal respiration and dyspnea. The latter led to shifts in the metabolic processes and to disturbance of the electrolyte metabolism at the cell level.


[The influence of oxygen barotherapy on erythropoiesis in the recuperative period of hemorrhagic collapse]. Under the effect of high-pressure oxygen therapy (2 atm of O2 for 40 min) in anemic rats (blood loss - 2,8% of body weight in the course of 30 min) erythropoiesis in the bone marrow was more intense and led to effective restoration of erythrocytes and hemoglobin in the peripheral blood. Biphasic character of accumulation of erythropoientins in the blood serum of rats was seen on the 1st and the 10th days after acute blood loss. Erythropoiesis inhibitor was revealed in the blood serum of rats on the 15th day. A conclusion was drawn on the importance of erythropoietins and high pressure oxygen therapy in the mechanism of blood regeneration following the loss of blood.


[The effect of intravenous novocaine administration on the outcome of hemorrhagic reactions]. Experiments conducted on 48 dogs and 50 rabbits showed that intravenous injection of novocain at various periods of the organism reaction to acute massive hemorrhage promoted an increase of survival and of the life span of the animals. Administration of the preparation increase the rate of flow, cardiac stroke and minute volume, and, on the whole, prevented the occurrence of late period of hemorrhagic shock. A conclusion was drawn that intravenous injections of novocain delayed the rate of development of the pathological process, and thus promoted more complete mobilization of the compensatory reactions.


[Neurospecific protein S-100 in the synaptosomes of rat cerebral cortex]. Neurospecific S-100 protein was revealed by the methods of microelectrophoresis in the 15% polyacrylamide gel with a 0.1% sodium dodecylsulfate and by a highly purified S-100 protein "marker" in the composition of low molecular acidic proteins of the rat brain synaptosomes. The S-100 protein conten constitutes about 15-2o% of the low molecular acidic synaptosomal porteins in the rat brain.


[Possible role of adenine nucleotide transport in regulating the respiration of rat liver mitochondria]. Studies with liver mitochondria from rats which starved for 48 hours showed the rate of ADP-stimulated respiration to be 20% lower than in the presence of an uncoupler. This effect was eliminated by preincubation of mitochondria with carnitine. Mitochondria from fed rats were characterized by a considerable decrease of states 3 and 4 respiration. In this case carnitine produced no effect. Preincubation of mitochondria from the liver of fed rats with alpha-ketoglutarate resulted in a substantial increase of the states 3 and 4 respiratory rates. There proved to exist at least two types of regulation of adenine nucleotide transport through the inner mitochondrial membrane depending on the metabolic state of the organism, i.e. by inhibition of adenine-nucleotide translocase by cytoplasmic acyl-CoAs and by control of intramitochondrial adenine nucleotide pool.


[The dynamics of serotonin in tissues in acute hypoxia (the phenomenon and its possible significance]. Serotonin (5HT) decreased in the bone marrow and renal cortex, and hyperserotoninemia developed immediately after one-hour hypoxia. Six-hour hypoxia was followed by an additional decrease of 5-HT in the kidney, medulla, spleen and thymus. Phasic changes of the 5-HT TOOK PLACE at the posthypoxic period. Apparently hypoxia led to the 5-HT mobilization and an increase of its biosynthesis. A possible significance of the 5-HT for the control of hemopoiesis both at the level of the kidney and directly al the level of hemopoietic cells is discussed.


[Changes in the creatine kinase activity of the brain, heart, liver and plasma of rats subjected to oxygen starvation]. The action of hypoxic and cytotoxic hypoxia on the creatine phosphokinase activity in the blood plasma, cardiac and hepatic tissue, cerebral tissue, as well as on the nuclear and mitochondrial cerebral fractions was investigated. Oxygen deficiency was followed by significant changes of the creatine kinase activity in all the tissues and cell fractions under investigation. The type of changes depended on the isoenzyme tissue perculiarities, as well as on the state of the enzyme oxidative phosphorylation systems and membrane permeability.


[The concentration and bisynthesis of ubiquinone-9 in the liver of white rats adapted to altitude hypoxia]. The content and biosynthesis of ubiquinone-9 in the thin slices of the liver of rats was studied during altitude adaptation. There was a three-fold acceleration of ubiquinone biosynthesis during the first period of altitude adaptation. Acceleration of biosynthesis of ubiquinone-9 in rat liver was insignificant after two weeks of adaptation. The content of ubiquinone-9 in rat liver changed but insignificantly in the course of one month of altitude adaptation.


[Hepatic and myocardial glucokinase, hexokinase and glucose-6-phosphate dehydrogenase activity in rabbits with pyrogenal fever]. The activity of glucokinase, hexokinase and glucose-6- phosphoric dehydrogenase of the liver and myocardium of rabbits was tested at different stages of pyrogenal fever with the aid of spectrophotometry. A marked decrease in the activity of the enzymes under study was observed in fever. After the subsidence of fever the activity of the enzymes became normal.


[Protein biosynthesis in the fibrillating perfused heart during normal oxygenation and following anoxia]. Methionine incorporation into proteins of the fibrillating dog heart perfused by donor circulation was investigated. In the heart in which fibrillation was induced by electric current under conditions of adequate oxygen supply a 50-55% increase of methionine S35 incorporation into the contractile protein fraction of both ventricles was observed. In the heart in which fibrillation appeared after anoxia, methionine S35 incorporation into the sum total proteins of the atria showed 40-60% depression, into the sarcoplasmic - 36 -53%, and into the contractile proteins of both ventricles - 18 -30% decrease.


[The influence of rabies immunization of gamma-aminobutyric acid metabolism in the brains of animals]. Subcutaneous injection to albino rats (100-120 g) of lived fixed rabies virus was accompanied by a brief marked decrease in the content of gamma-aminobutryic acid in the animals' brain. There was also an increase in the activity of gamma-aminobutyric acid alpha-ketoglutaric acid transaminase in the brain tissue of animals vaccinated with live fixed rabies virus.


[The effect of long-term nitrazepam administration on sleep cycles in rats]. Single and chronic administration of a low dose of nitrazepam (1 mg/kg) had no effect on sleep cycles in rats. A single injection of a high dose (10 mg/kg) of nitrazepam resulted in prolongation of the total duration of synchronized sleep with a corresponding shortening of desynchronized (paradoxical) sleep. The number of sleep cycles was reduced. Chronic injections of nitrazepam (for 7-14 days) in a dose of 10 mg/kg evoked a gradual prolongation of the duration of paradoxical sleep and an increase in number of sleep cycles. After discontinuance of a long-term administration of nitrazepam (1 mg/kg or 10 mg/kg) prolongation of desynchronized sleep and an increase in the number of sleep cycles were more pronounced in comparison with the last day of chronic administration of the drug.


[Correlation analysis in studying the mechanism of action of smooth muscle stimulants]. The presence of correlation between the value of the maximal effects of acetylcholine and other cholinomimetics, as well as serotonin, barium chloride and depolarizing solution was studied on an isolated strip of rat stomach. It was shown that the effect of acetylcholine closely correlated with the effects of other cholinomimetics, to a lesser degree with the effects of barium chloride and depolarizing solution, and least of all with the effect of serotonin. It is proposed to use the degree of this correlation to analyze the point of action of different drugs and processes of coupling the receptor stimulation with the observed effect. It was shown that the point of convergence of the ways of coupling of the three latter influences preceded the convergence of their common way with the way of coupling of the cholinomimetic effects.


[The influence of the thermal factor on the antigenic properties of skin]. Results of immunochemical studies of normal and thermally-treated human skin in vitro showed at least 2 of 4-5 organospecific dermal antigens to be thermostable-they withstood heating at 100 degrees C for 3 minutes; 2 or 3 antigens were thermolabile. The thermostable antigens possessed electrophoretic migration in the field of alpha1- and gamma-globulins. The burn eschar was found to retain one of the two thermostable oranospecific antigens together with the loss of thermolabile antigen.


[The effect of specific sensitization and corticosteroid hormones on the course of experimental antimycotic infection]. Infection of mice and rats with actinomycetes against the background of hydrocortisone administration led to acute actinosepsis of animals to actinomycetes or extracellularly-secreted products of microbial activity contributed to the transformation of an acute infectious process into chronic, with the formation of actinomycetes hyphae in the organs. Chronic actinomycosis courses in the presence of the circulating antibodies mainly against the extracellularly-secreted products of actinomycetes vital activity.


[Changes in resistance to the tumor process subserved by the presence of a focus of tuberculosis mycobacteria in the lungs]. Tumours were induced in rats with the aid of 20-methylcholantrene. Preliminary (11 to 13 days before) administration into the lung tissue of Mycobacteria tuberculosis in the composition of the water-oil emulsion decreased the animal resistance to the tumour origination. This effect is supposed to be caused by an intensification of the autoimmune processes as a result of mycobacteria administration.


[The sensitivity of human melanoma heterotransplants to chemotherapeutic action]. There were revealed considerable individual differences in the sensitivity of human melanomas cultivated in diffusion chambers in the abdominal cavity of mice and the explants into the cheek pouches of Cricetus auratus W. to the combined action of three drugs: vincristin (or vinblastin), nitrosomethylurea, and dactinomycin. In comparing the results obtained in these two variants of investigations they proved to coincide in 3 of 5 cases. In 2 cases a negative result obtained in experimentas with Cricetus auratus W. corresponded to the positive result in experiments with diffuse chambers.


[Circadian rhythm of the mitotic activity of pulmonary interalveolar septum cells in rats of different ages]. The daily rhythm of mitotic activity in the lungs of the 20-day-dd embryo coincides with the rhythm of the adult organism. The mitotic activity of the 1-, 3- and 10-day-old animals was the maximum in the evening and the minimum-in the morning hours. A definitive rhythm of cells division (with the maximal mitotic activity in the morning and the minimal-in the evening) is established beginning from the 17th day of the postnatal development. The average mitotic activity is very high in the embryos, but it falls immediately after birth. It rises on the 3rd day, and begins to decrease again from the 7th day after birth.


[Circadian rhythms in connective tissue]. A study of circadian rhythms in the connective tissue showed cell elements (particularly histiocytes) to be characterized by circadian rhythms of the metabolic processes. This is expressed in a distinct diurnal activity of the succinic dehydrogenase (SDH) and lactic dehydrogenase (LDH). In the processes of adaptation to the high altitude hypoxia the activity of SDH and LDH was higher than in control, but dynamics of the changes of their activity repeated the changes in control group. It is concluded that circadian rhythms of the metabolic processes in the connective tissue were sufficiently stable: no visible changes were observed during adaptation to high altitudes.


[Physiologic regeneration of jejunal epithelium following bilateral subdiaphragmatic vagotomy in rats]. Seven days after vagotomy in rats there was an increase of the mitotic activity of the epithelium of the small intestine; this index was about 1.5 greater in the experimental ats in comparison with control animals. Daily rhythm of the mitotic activity was constant under these conditions, but the amplitude of daily fluctuations was levelled. Vagotomy failed to alter the stable regimen of renovation of the cell population of the "crypt-villus" system.


[Changes in the mitotic regime of a cell culture under the influence of sensitins]. A study of the effect of three types of lyophilized sensitin preparations on cell culture of human amnion showed an increase in the amount of pathological mitoses, arrest of division at the metaphase and the appearance of chromosome adhesions absent in the control culture. These changes pointed to destructive action of the preparations under consideration on chromosomes and achromatine spindle, and from the author's point of view, characterized toxic properties of sensitin.


[Self-maintenance of induced bone tissue]. The capacity for self-maintenance of the bone marrow osteogenic precursor cells from the skeletal bones and from the bones induced by implantation of decalcified bone matrix is compared. Transplantation in diffusion chambers is employed as the test system. Osteogenesis in the bone marrow transplants isolated from the skeletal bone lasts several months, whereas osteogenesis in the bone marrow transplants isolated from induced bone stops after the second month. Fibroblasts arising in the monolayer cultures of the skeletal bone marrow retained their osteogenic potencies after repeated passages. On the contrary, fibroblasts from the monolayer cultures of induced bone marrow lost their osteogenic capacity after the second passage. Thus, contrary to osteogenic precursors of the skeletal bone, osteogenic precursors of induced bone tissue had a very limited self-maintaining capacity after the cessation of induction.


[A cytochemical study of binaurally converging connections in the nuclei of the cat superior olive]. Experiments of binaurally converging connections on the level of the superior olive nuclei was carried out on anesthetized cats by the method of quantitative cytospectrometry. A considerable increase in the cytoplasmic RNA content in the neurons of the ipsi- and contralateral medial and lateral nuclei was observed following a 2-hour monaural stimulation by rhythmical sound (noise) signals. The volume of the functioning neurons of the nuclei under study showed either no significant change or increased. The data obtained demonstrated the nature of functional organization of the binaurally converging connections.


[Effector innervation of melanophores of the arteries of the base of the brain]. Melanophores in the arteries of the base of the brain of kittens displayed pronounced variations in size and shape in response to the peripheral electrical stimulation of the vagus and the sympathetic nerves. These melanophores changed their size and shape under the influence of acetylcholine and noradrenaline solutions in vitro too. The present experiments showed melanophores to have a double effector innervation.


[The vesicular system of the endothelium in the blood-carrying capillaries of the diaphragm with different functional states]. Micropinocytotic vesicles were counted in the endothelial cells of blood capillaries in the muscle of the diaphragm in its indirect rhythmic stimulation at a frequency of 50 imp/s after section of the phrenic nerve, and also in natural contraction and relaxation of the muscle during respiration. A change in the total count of the vesicles and even more pronounced changes in the ratio of the vesicles bound with plasmic membranes and freely located in the cytoplasm of the cells were revealed; this pointed to the change in the transendothelial transfer of substances. It appeared that the state of the process of vesicle formation could influence the method of fixation applied.


[Metabolic disorders and plasmorrhagia in myocardial cells following adrenalin damage]. The authors examined serial sections of the myocardium of rats sacrificed at periods of from 1 to 24 hours after adrenalin administration. The results of histoenzymatic reaction to succinic dehydrogenase (a test for cell injury) were compared with the data obtained in fibrin detection by Coons' method. Plasmorrhagia into the irreversibly injured muscle cells had a characteristic appearance in the test with nitro-BT; there proved to be no fibrin in the fibers with fatty dystrophy marked by macrogranular depositions of formazan. A supposition was put forward on different pathogenesis of the reversible and irreversible injuries of the myocardium caused by adrenalin administration.


[Electrophysiological analysis of the effect of cortisone on the rat neuromuscular apparatus]. The influence of cortisone (1.5 mg per 100 g of body weight, daily, for 10 days) on the neuro-muscular system was studied in rats in situ. The action potentials of the nerve and muscle were recorded with the extracellular electrodes. The rest potentials (RP) of the muscle fibers and the miniature end-plate potentials (MEPP) were recorded with the intracellular glass microelectrodes. A decrease of the RP and the MEPP amplitude, and an increase of the MEPP frequency and prolongation of the neuromuscular transmission time were revealed in rats given daily doses of cortisone, 1.5 mg/100 g of body weight, during 10 days; reliability of the neuro-muscular transmission (acceleration of the fall of the muscle action potential amplitude during tetanus) proved to decrease under the action of cortisone.


[Urea and amino acid transport by an isolated human placenta]. A method of bilateral perfusion of the isolated human placenta was used to study the urea transport from the fetal placental stream into the maternal one, and of amino acid transport in the opposite direction. Experiments demonstrated that the method provided a sufficiently full perfusion of the intervillous space and offered possibilities for studying the placental transport. With equal amino nitrogen concentration in both circulations, its content in the fetal stream increased during the experiment. This elevation was more expressed when amino acid was added to the maternal circulation. The idea of amino acid "secretion" by the trophoblast cell elements into the fetal circulation was confirmed by the above experiments.


[Participation of adrenal hormones in the genesis of arterial hypertension of hypothalamic origin]. Continuous many-hour stimulation of the hypothalamic negative emotiogenic centres (ventromedial nuclei) evoked a stable arterial hypertension with a peculiar phasic dynamics of the adrenal secretory activity in waking immobilized rabbits. Bilateral extirpation of the adrenal glands decreased the initial level of the average arterial pressure, inhibiting development of stable arterial hypertension. Many-hour stimulation of the mentioned structures also produced stable arterial hypertension in adrenalectomized rabbits if preceded by the administration of hydrocortisone together with adrenaline. Against the background of separate administration of hydrocortisone and adrenaline to adrenalectomized rabbits, many-hour stimulation of the ventromedial hypothalamus evoked a short-term rise in the arterial pressure. A conclusion was drawn that activation of hormones of the adrenal cortical and medullary layers played an important part in the formation of stable arterial hypertension in rabbits under continuous many-hour stimulation of the hypothalamic negative emotiogenic centres.


[Tissue respiration of rat internal organs and skin during prolonged exposure to high ambient temperature]. Oxygen consumption by tissues of various organs was studied in acute experiments on albino rats in Warburg apparatus at a temperature of 37 degrees C. High environmental temperature proved to decrease the tissue gas exchange level. Participation of different organs in the reduction of total metabolic level varied and depended on the number of actions of the thermal factor. A more active inclusion of the majority of the organs into the adaptive reactions of the organism to the high temperature occurred during the third week.


[Hemodynamic analysis of the hypotensive effect of portacaval transposition of vessels in vasorenal hypertension]. Experiments were conducted on unanesthetized dogs; the influence of portocaval transposition on the systemic hemodynamics of the intact dogs and dogs with experimental vasorenal hypertension was studied. Arterial pressure was decreased in dogs with vasorenal hypertension after portocaval transposition mainly by means of reduction of the total peripheral resistance. There was no considerable change of hemodynamics in the intact dogs after the portocaval transposition.


[Absorptive-excretory function of isolated dog liver during its perfusion]. Twenty experiments were performed on mongrel dogs. The absorptive and excretory function of the liver in the intact organism and during its isolated perfusion through the portal vein with the use of extracorporeal circulation was studied by means of the bromsulfaline test. The absorptive function of the perfused liver proved to decrease by 50-60 per cent. The rate of bile elimination and plasma clearance was 5-6 times higher at the beginning of the experiment in the intact organism. Later on, the difference in the degree of retention of the hepatic excretory function was reduced. Hypoxia connected with denervation, hepatectomy and the isolated perfusion proper apparently served as the principal cause of reduction of the absorptive-excretory function of the isolated liver.


[Heparin and mast cells in the dynamics of experimental extrahepatic cholestasis]. The content of heparin in the blood and mast cell count in rat tissues were studied during different periods of experimental extrahepatic cholestasis induced in rats by ligation of the common bile duct. During cholestasis the blood heparin level proved to increase and the mast cell count fell on the 3rd day, increased on the 7th day and fell again on the 14th day. Correlation between the degranulated and nondegranulated forms of mast cells altered in favour of the latter. The fluctuation of mast cell counts and increase of degranulated forms is considered to be the best result of mast cell irritation produced by bile acids and pigments which accumulated in the organism.


[Use of DNA in cytopenia induced by myelosan]. Wistar rats weighing 180-190 g received myleran per os in a single dose of 10 mg/kg, or fractionally (total dose of 25 mg/kg) for 18 days. After myleran administration the animals were injected 4-5 times (every other day) with a homologous DNA in a dose of 2 mg per rat or with a standard salt citrate. The DNA injection reduced the duration of leukopenia. With the least dose of myleran leukocyte count returned to the normal in 6 days in the treated animals and in 25 days in the untreated controls and with the highest dose -- in 15 and in 25 days, respectively, from the beginning of the treatment. The differences in the leukocyte count between the treated and control rats in both experiments were mainly due to the dynamics of neutrophils, the content of which in the treated animals exceeded that in the untreated animals by 54-110% in the course of 6-15 days in the first, and by 23-38% in the course of 10-23 days in the second experiment.


[Regulation of mitochondrial membrane permeability by a factor from mitochondrial interaction]. It was shown that a factor from the thyroxine-injured mitochondria caused inhibition of mitochondrial swelling in isotonic KNO3 and NH4NO3 solutions in the presence of rotenone. These data were interpreted as permeability inhibition for K+ and H+ ions.


[Change in the content of ATP and 2,3-diphosphoglycerate in the erythrocytes of rats adapted to hypoxia]. It was shown that on the 30th-60th days of training rats to hypoxia under conditions of pressure chamber there was an increase in ATP and 2,3-diphosphoglycerate content in erythrocytes. By changing the affinity of hemoglobin to oxygen the mentioned shifts could play an important role in the improvement of oxygen supply to the tissues.