Hepatic lesions and hemolysis following administration of 3alpha, 7alpha, 12alpha-trihydroxy-5beta-cholestan-26-oyl taurine to rats. Patients with a metabolic block in the conversion of THCA into cholic acid develop cirrhosis and hemolysis, and die of hepatic failure. In these patients, THCA is largely conjugated to taurine (tauro-THCA) and excreted instead of being converted into cholic acid. In the present study, the effects of tauro-THCA on hemolysis, bile flow, and hepatic morphology were evaluated in bile fistula rats. All rats infused with tauro-THCA at rates of 0.25, 0.50 or 0.75 micronmol/min developed hemolysis with hemoglobinuria. A direct toxic effect of tauro-THCA on washed human red blood cell membranes was demonstrated at a concentration of 8 X 10(-4) M. Liver biopsy sections from rats infused for a 2 hr period with tauro-THCA were examined by electron microscopy and showed dilation of the rough endoplasmic reticulum and distortion of mitochondrial membranes. Cholestasis was not induced, since tauro-THCA actually caused a greater choleretic response for a given rate of bile salt excretion than did taurocholate. This study raises the possibility that the clinical liver disease seen in patients with a metabolic block in the conversion of THCA into cholic acid may be caused by tauro-THCA.


Differences in response to sodium administration in normotensive white and black subjects. In order to examine possible differences in PRA, PA, and renal electrolyte excretion in normotensive black and white subjects, we studied 68 age-matched subjects: 19 white men, 19 black men, 15 white women, and 15 black women. PRA was measured before and after the infusion of 2 L of normal saline to evaluate suppression of the renin-aldosterone system. The excretion of sodium, potassium, and creatinine in response to the salt load was monitored for 24 hr. PRA and PA measurements were repeated after 2 hr of ambulation on the morning following salt loading. Dietary sodium was then restricted and oral furosemide (120 mg) was administered in order to assess PRA and PA responsiveness to sodium and volume depletion. White and black subjects had similar PRA and PA responses to normal saline and furosemide administration. Over a 24 hr period, black subjects excreted significantly less sodium and potassium following the salt load than did white subjects. The PRA values of black subjects 24 hr following the salt load were significantly suppressed as well. These observations suggest that there may be racial differences in renal sodium excretion reflected by decreased urinary sodium excretion and a relative suppression of PRA following a salt load in black persons.


A simple rapid radiometric assay for pyrimidine-5'-nucleotidase. Pyrimidine-5'-nucleotidase deficiency appears to be an important cause of hemolytic anemia associated with basophilic stippling of the red cells. A new radiometric method for the assay of this enzyme has been developed. In this technique, 14C-CMP serves as substrate. The CMP which is not dephosphorylated to cytidine is bound to the barium sulfate precipitate which forms in the deproteinization process. The cytidine remains in solution and is counted. The method is simple and reproducible and can be carried out on large numbers of samples. Two patients with pyrimidine-5'-nucleotidase deficiency have been detected by means of this technique.


The effect of immunosuppressive and anti-inflammatory drugs on monocyte function in vitro. MNL cellular chemotaxis, bacterial killing and phagocytosis, and Oil Red O phagocytosis were studied in vitro in the presence of eight anti-inflammatory or immunosuppressive drugs. Inhibition of Boyden Chamber migration of MNL's in a MNL-lymphocyte mixture was achieved after 1/2 hr incubation by 10(-3) and 10(-4) mol/L. concentrations of chloroquine (maximum inhibition 63% +/- 2.8), dexamethasone (58% +/- 8.6), 6-mercaptopurine (62% +/- 4.2), methotrexate (66% +/- 6.4), and vinblastine (100%). Bacterial killing was not significantly affected by any of the drugs studied. Bacterial phagocytosis was improved by vinblastine at 10(-3) and 10(-4)M and by 6-mercaptopurine at 10(-5)M, but there was apparent interference with the assay at high drug concentrations. Modification of the Oil Red O technique showed inhibitions of MNL phagocytosis by vinblastine at 10(-3)M (69% +/- 2.8 inhibition), chloroquine at 10(-3)M (49% +/- 8.5), and mercaptopurine at 10(-3)M (32.5% +/- 0.7). Cyclophosphamide, although reported to require hepatic conversion in vivo, may be partially activated in a lymphocyte-MNL mixture in vitro, producing a decrease in cell viability but no statistically significant impairment of MNL function. These results support direct inhibition of MNL cellular function as one of the mechanisms of the anti-inflammatory action of chloroquine, dexamethasone, methotrexate, 6-mercaptopurine, and vinblastine.


Maintenance of hemopoietic stem cells in diffusion chamber cultures. When murine bone marrow cells are cultured in DC's in irradiated host mice, there is an initial phase of rapid white cell growth followed by prolonged maintenance of steady-state granulopoiesis. This study examined the role of hemopoietic stem cells in this culture system. During the initial growth phase there was a rapid increase in both pluripotential stem cells, CFU-S, and commmitted white cell precursors, CFU-C. The increase in CFU-C was larger, occurred more rapidly, and was biphasic in nature. After day 7 and until at least day 16, the numbers of CUF-S, CFU-C and total white cells were all maintained at relatively constant plateau levels which were typically well below the maximal capacity of the culture system. During the plateau phase the number of CFU-S was slightly greater than the number initially placed in culture, whereas CFU-C had increased by a factor of 2.3 and total white cells by a factor of 10. This appears to reflect a system of growth amplification, with preferential differentiation of CFU-S into CFU-C and thence into the pathway of white cell development. The plateau phase of culture has received very little attention but appears to represent a model, in a closed culture system, of finely regulated granulopoiesis, with an equilibrium between constant numbers of hemopoietic stem cells and their differentiating white cell progeny.


Early repair of blast ruptures of the tympanic membrane. A method and results of early repair of blast rupture of the tympanic membrane in 24 selected cases, where flaps and/or free edges of the torn eardrum could be detected by examination with the operating microscope, are presented. By reversion of the flaps and approximation of the edges, the perforation was closed or significantly diminished. This ensured the healing of the tympanic membrane in all cases within days instead of months. No complications were noted during a subsequent two to three-years' follow-up. The improved hearing was stable.


Oncocytic hyperplasia of the larynx.

Oncocytic hyperplasia of the larynx. Oncocytic hyperplasia of the larynx is rare. The lesion most commonly arises from the false vocal chord. A distinction arises between oncocytomas of the salivary glands which are considered to be neoplasms and extrasalivary oncocytic lesions which are secondary to hyperplasia. Oncocytic lesions of the larynx are benign and treatment is excision. They may be multiple, but recurrences are rare.


Congenital epulis. Report of a case.

Congenital epulis. Report of a case. The clinical characteristics and histogenesis of congenital epulis, the tumour often confused with granular cell myoblastoma, are discussed and a case of our own is presented.


The clinical assessment of cochlear implant patients. This study outlines the clinical assessment procedures adopted in the Department of Otolaryngology at the University of Melbourne for patients being considered for a cochlear implant. As the procedure is new and requires rigorous evaluation, it is considered preferable only to operate on a limited number of patients, and ensure that they have a thorough evaluation both before and after surgery. This should be carried out by a team whose members have experience in otology, audiology, aural rehabilitation, acoustics and psychology. The indications and contraindications for surgery are also outlined.


Hereditary deafness associated with branchial fistulae and external ear malformations. Two families are presented in which affected members had deafness, preauricular sinuses, branchial fistulae and malformation of the external ear. In Family I, a renal abnormality was an associated feature. In Family 2, two individuals had an abnormality of the incudostapedial joint. In both families inheritance was autosomal dominant with variable expressivity. The occurrence of external-ear malformations, branchial fistulae, and preauricular sinuses should indicate the need to search for a hearing loss not only in the patient but amongst relatives.


Sensorineural deafness associated with recessive hypophosphataemic rickets. Two pairs of siblings suffering from recessive hypophosphataemic rickets are presented, three members of which have some degree of sensorineural deafness and all of which have bilateral marked narrowing of the internal auditory canals. The biochemical explanation of the condition is discussed.


Hamartoma of nasopharynx.

Hamartoma of nasopharynx. The extreme rarity of nasal and nasopharyngeal hamartoma, and its possible confusion in early diagnosis, prompted us to undertake a brief review of hamartomatous masses in E.N.T. practice along with this case report.


Recurrent multiple rhinosporidiosis with osteolytic lesions in hand and foot. A case report. A case of multiple recurrent Rhinosporidiosis with lytic lesions in the bones of hand and foot are reported. To the best knowledge of the authors this is the first reported case of Rhinosporidiosis with lytic lesions in bones other than of the nose.


Necrotizing otitis externa.

Necrotizing otitis externa. Three cases of Necrotizing Otitis Externa are described and a suggestion made of a possible relation between the severity and progress of the disease and the degree of pneumatization of the mastoid.


Insensitivity of large rat adipocytes to the antilipolytic effects of insulin. The ability of insulin to inhibit epinephrine-stimulated lipolysis was compared in large and small rat adipocytes. Large cells were obtained from older, obese animals (greater than 12 months old and greater than 500 g) and small cells were obtained from younger, leaner animals (4-5 weeks ild, 140-160 g). When full insulin dose response studies were conducted it was found that large adipocytes were less sensitive to the antilipolytic effects of insulin. Thus, decreased insulin responses were seen at low insulin concentrations, while normal inhibition of lipolysis was seen at a maximally effective insulin concentration. In other words, the dose response curve for insulin's antilipolytic action was shifted to the right, and this is consistent with the previously reported decrease of insulin receptors in these cells. Furthermore, since the maximal antilipolytic response to insulin was fully normal in large adipocytes, the data also indicate that the post receptor antilipolytic system is intact in these cells.


Lipids of the anal sac secretions of the red fox, Vulpes vulpes and of the lion, Panthera leo. Lion anal sac secretion were found to be richer in lipids and to contain more complex less uniform mixtures of lower moleculas weight lipids then the anal sac of the red fox. In the lion, homologous series of 1-alkylglycerols and 2-hydroxy-fatty acids were identified. Phenylacetic, 3-phenylpropionic, and related hydroxylated acids were also observed. Gas-liquid chromatography profiles of fox anal sac secretion lower molecular weight lipids were found to be less variable in their major constituents and to be dominated by relatively few large peaks, mainly (derivatized) fatty acids. Indole was also identified. Free cholesterol, and occasionally, stanols were observed in fox and lion secretions. In the red fox, total cholesterol levels averaged 0.93 mg/g (% free, 56.4), n = 5. Findings are discussed in relation to histological and anatomical similarities and differences between the anal sacs of the lion and the fox and in the context of the role of these secretions in chemical communication.


Synthesis of sulfate esters of lithocholic acid, glycolithocholic acid, and taurolithocholic acid with sulfur trioxide-triethylamine. The facile synthesis of lithocholic acids sulfates by a procedure that produced the desired products in over 90% yield is described. Lithocholic acid sulfate and glycolithocholic acid sulfate were synthesized by reacting lithocholic acid or glycolithocholic acid with sulfur trioxide-triethylamine complex in dimethylformamide for 0.5-1 hr. Taurolithocholic acid sulfate was obtained by conjugating lithocholic acid sulfate with taurine in dimethylformamide at 90 degrees C for 0.5 hr. The one-pot synthesis of taurolithocholic acid sulfate starting from lithocholic acid is also described. This procedure, which generated lithocholic acid sulfate in situ, produced taurolithocholic acid sulfate in 98% yield, compared to an overall yield of less than 10% obtained by previously published procedures.


Electron microscopic studies of the assembly, intracellular transport, and secretion of chylomicrons by rat intestine. A detailed ultrastructural investigation of the assembly, intracellular transport, and secretion of chylomicrons by rat proximal jejunal intestinal cells was performed in rats fed corn oil. Following fat feeding the smooth endoplasmic reticulum of the absorptive cells becomes laden with triglyceride droplets which are transported through channels of the endoplasmic reticulum to the Golgi apparatus. The Golgi zones become extremely prominent due to the accumulation of osmiophilic droplets, similar in size and configuration to chylomicrons, within proliferated Golgi vesicles. Golgi-derived secretory vesicles, containing nascent chylomicrons, migrate towards the lateral cell membrane. The secretory vesicle membranes fuse with the lateral plasmalemma and nascent chylomicrons are then discharged into the intercellular spaces. Alterations of specific domains of the secretory vesicles were prominent, appearing as coated pits. Coated pits were apparent in the lateral plasmalemma in areas of active chylomicron exocytosis suggesting their derivation from secretory vesicle-membrane fusion. Chylomicrons, within the intercellular spaces, pass through the basement membrane that lines the basal surfaces of the epithelial cells, traverse the cellular elements of the lamina propria, and finally gain access to the lymphatics entering these channels through gaps between adjacent endothelial cells. These observations indicate that nascent chylomicrons accumulate within Golgi vesicles as a pre-requisite to secretion and that secretion occurs by exocytosis resulting in the release of nascent chylomicrons from secretory vesicles.


Glycosphingolipids from cultured astroblasts. The glycolipids of two clonal lines astroblasts, NN clone and C6 clone, were studied. Glucosylceramide and lactosylceramide were present at very low levels in both clones, but the most common myelin glycolipids galactosylceramide and sulfatide, were not detected. The ganglioside pattern of these cells was rather simple, with GM3 as main compoenent, accompained in one clone by GD3. These results are quite different from those observed on astroglia-enriched fractions isolated from brain. The fatty acid composition of these glycolipids was studied. Long chain fatty acids, up to lignoceric acid, were found in appreciable amounts, even in gangliosides. It is difficult to conclude if these glycolipid patterns are due to the properties of normal astroblasts, to transformation, or to a tumoral character of our cell lines.


Lysophospholipase--transacylase from rat lung: isolation and partial purification. Incubation of rat lung supernatant with 1-[1(-14)C] palmitoyl-sn-glycero-3-phosphocholine in the absence of any cofactors resulted in the release of radioactive fatty acid and the formation of phosphatidylcholine. The production of fatty acids (lysophospholipase activity) exceeded phosphatidylcholine formation (transacylase activity) about thereefold, although the relative extent of phosphatidylcholine formation was considerably greater than previously reported by Abe et al. (Biochim. Biophys. Acta, 369: 361-370, 1974). In agreement with these authors, evidence is presented suggesting that a single enzyme is responsible for both catalytic activities. The enzyme, provisionally denoted lysophospholipase-transacylase, was found primarily in the soluble fraction of rat lung and was purified approximately 250-fold. The enzyme had an estimated mol wt of 50,000. The ratio of lysophospholipase to transacylase activity in the purified enzyme could be varied depending upon the concentration and character of the lysophosphatidylcholine and the ration of substrate to products. The degree of esterification of 1-acyl lysophosphatidylcholine was altered with mixtures of different molecular species of substrate, indicating acyl chain selectivity in the transfer process. This enzyme was capable of synthesizing disaturated phosphatidylcholine, an important component of the pulmonary surfactant. Three lysophospholipases purified from other sources did not possess this transacylase activity.


A comparison of insulin binding by liver plasma membranes of rats fed a high glucose diet or a high fat diet. The interaction of (125)I-labeled insulin with purified liver plasma membrane from rats fed a high fat (L) diet or a high glucose (G) diet was studied with respect to specific binding, insulin degradation, binding site degradation, and rate of hormone association and dissociation. Scatchard analysis suggested the presence of high and low affinity binding sites for membranes of both G and L diet-adapted rats. However, liver plasma membrane from rats fed the high glucose diet bound 50% more insulin than did membrane from rats fed the high fat diet. Diet did not change insulin binding site degradation. The results suggested that an apparently reduced number of insulin binding sites (G = 10.2 +/- 2.45 x 10(-12) mol/mg membrane protein, L = 4.5 +/- 1.73 x 10(-12) mol/mg membrane protein) associated with fat feeding as compared to glucose feeding was responsible for the reduced insulin binding by membrane from rats fed the high fat diet. The effects of concanavalin A (Con A) on insulin binding to liver plasma membranes were also investigated. Con A enhanced the specific binding of insulin to liver plasma membranes from rats fed either diet at concentrations lower than 50 micro g/ml, whereas at concentrations higher than 50 micro g/ml Con A inhibited insulin binding to these membranes. The stimulatory effect of Con A on insulin binding at low concentrations was greater and inhibition of binding at high concentration was less in the case of membrane prepared from L diet-adapted animals. These results suggested that diet can modify the plasma membrane glycoproteins.


Direct transesterification of lipids in mammalian tissue for fatty acid analysis via dehydration with 2,2'-dimethoxypropane. A method is described for the transesterification of lipids of mammalian tissues for fatty acid analysis by gas-liquid chromatography (GLC) that eliminates the extraction step of conventional procedures. The method involves the direct reaction of anhydrous HCl-methanol with the lipids in approximately 10 mg of tissue or 0.1 ml of serum after removal of water by reacting it with 2,2'-dimethoxypropane (DMP). Acetone and methanol produced from water in the sample, as well as the excess DMP, are evaporated prior to transesterification in order to eliminate the formation of artifacts from the solvents. The method was demonstrated with rat serum and brain tissue.


Quantitative determination of hepatic and lipoprotein lipase activities from human postheparin plasma. A method was developed to separate and quantitatively determine two different triglyceride lipase activities in human postheparin plasma: hepatic triglyceride lipase (H-TGL) and lipoprotein lipase (LPL). Affinity chromatography on heparin-Sepharose columns was used for the separation. Rechromatography of purified H-TGL on heparin-Sepharose resulted in recoveries of 74 and 97% of these enzyme activities, respectively. The analytical errors for the determinations of the two activities were 11.4 and 9.6%, respectively.


An improved method for the preparation of unsaturated phosphatidylcholines: acylation of sn-glycero-3-phosphorylcholine in the presence of sodium methylsulfinylmethide. An improved method for the partial chemical synthesis of unsaturated and radioactively labeled phosphatidylcholines is described. This procedure offers advantages over conventional acylation methods in that it can be carried out on a millimole or micromole scale under mild conditions and it does not require a large excess of the fatty acid acylating reagent. In this procedure sn-glycero-3-phosphorylcholine is reacted with twice the theoretical amount of fatty acid imidazolide and sodium methylsulfinylmethide in dimethylsulfoxide for several minutes at 17 degrees C. Phosphatidylcholine, which was purified by gradient-elution chromatography on silicic acid, was isolated in 60% yield and was estimated to be about 99% pure. The preparations of 1,2-dioleoyl-, 1,2-dilinoleoyl-, and 1,2-dilinolenoyl-sn-glycero-3-phosphorylcholine are described. The reaction was also carried out on a small scale for the preparation of high specific activity 1,2-di[ 1'(-14)C]oleoyl-sn-glycero-3-phosphorylcholine in 38% yield with a specific activity of about 9.7 muCi/mumol.


Improved techniques for studies of adipocyte cellularity and metabolism. Two methods are described for the study of adipose tissue cellularity and metabolism. In the first, 8 M urea was used to liberate osmium tetroxide-fixed adipocytes from the connective tissue matrix. In the smaller-sized cell ranges there was a significant reduction in apparent adipocyte number of rat, pig, and beef adipose tissue with 8 M urea treatment. This was attributed to solubilization of connective tissue debris that was counted as adipocytes in samples isolated without urea. There was no effect on the larger cell-size fractions with 8 M urea treatment. Eight molar urea had no effect on fixed adipocyte retention of radioactivity. The second method entailed the use of hydrogen peroxide to volatilize the black, osmium tetroxide-fatty acid complex of osmium tetroxide-fixed adipocytes, containing radioactivity, resulting in colorless lipid suitable for liquid scintillation counting. This latter technique permits incubation of unfixed adipose tissue slices with a radioactive substrate, followed by fixation with osmium tetroxide and subsequent separation of the adipocytes, by screening, into the desired size ranges. Adipocytes in various size fractions can then be counted, sized, and then decolorized with hydrogen peroxide in order to quantitate the amount of radioactivity within the adipocytes. There was no loss of radioactivity from the fixed cells with hydrogen peroxide treatment.


A model of optimal voluntary muscular control. In the absence of detailed knowledge of how the CNS controls a muscle through its motor fibers, a reasonable hypothesis is that of optimal control. This hypothesis is studied using a simplified mathematical model of a single muscle, based on A.V. Hill's equations, with series elastic element omitted, and with the motor signal represented by a single input variable. Two cost functions were used. The first was total energy expended by the muscle (work plus heat). If the load is a constant force, with  no inertia, Hill's optimal velocity of shortening results. If the load includes a mass, analysis by optimal control theory shows that the motor signal to the muscle consists of three phases: (1) maximal stimulation to accelerate the mass to the optimal velocity as quickly as possible, (2) an intermediate level of stimulation to hold the velocity at its optimal value, once reached, and (3) zero stimulation, to permit the mass to slow down, as quickly as possible, to zero velocity at the specified distance shortened. If the latter distance is too small, or the mass too large, the optimal velocity is not reached, and phase (2) is absent. For lengthening, there is no optimal velocity; there are only two phases, zero stimulation followed by maximal stimulation. The second cost function was total time. The optimal control for shortening consists of only phases (1) and (3) above, and is identical to the minimal energy control whenever phase (2) is absent from the latter. Generalization of this model to include viscous loads and a series elastic element are discussed.


Pattern formation by the global limits of a nonlinear competitive interaction in n dimensions. This paper describes a class of nonlinear systems that include processes of pattern formation, short term memory, interpopulation competition, and parallel processing. These systems show how continuously fluctuating data patterns can be processed by noisy populations having finitely many excitable sites. Particular examples are found in vertebrate retina and sensory cortex, as well as certain nonneural developing tissues. After an initial period of seemingly random behavior, that is described by a finite series of iterated decisions or enhancement steps, a global consensus or asymptotic pattern is reached. This is true given any number of competing populations, any mean competition function, and any number of random factors determining interpopulation signals. Which pattern will be chosen can depend on initial data and system structure in a complicated fashion. The results demonstrate a robust design that joins together the dynamics of mass action, the geometry of interpopulation competition, and the statistics of signal generation.


Time delays in single species growth models. A general model is considered for the growth of a single species population which describes the per unit growth rate as a general functional of past population sizes. Solutions near equilibrium are studied as function of epsilon = 1/b, the reciprocal of the inherent per unit growth rate b of the population in the absense of any density constraints. Roughly speaking, it is shown that for large epsilon the equilibrium is asymptotically stable and that for epsilon small the solutions show divergent oscillations around the equilibrium. In the latter case a first order approximation is obtained by means of singular perturbation methods. The results are illustrated by means of a numerically integrated delay-logistic model.


Stability in a class of discrete time models of interacting populations. Effective Lyapunov and Lyapunov-like functions for a class of discrete time models of interacting populations are presented. These functions are constructed on the biologically meaningful principle that a viable population must absorb energy from external sources when its density is low and it must dissipate energy to the environment when its density is high. These functions can be used to establish that a discrete time model is globally stable or that its solutions are ultimately confined to an acceptable region of the state space. The latter is especially interesting when the model has chaotic solutions. These methods are applied to a single species model and a model of competition between two species.


Stability in Gilpin and Ayala's models of competition. Simple and effective conditions for global stability in a class of models for m competing species are given. A numerical method is used to establish a large finite region of attraction for the feasible equilibrium in Gilpin and Ayala's model of two competing Drosophila populations.


Theory reduction and non-Boolean theories. It is suggested that biological theories should be embedded into the family of non-Boolean theories based on an orthomodular propositional calculus. The structure of universal theories that include quantal phenomena is investigated and it is shown that their subtheories form a directed set which cannot be totally orders. A precise definition of theory reduction is given; it turns out that hierarchically different descriptive levels are not related by a homomorphic map. A subtheory that is reducible to a more general theory can be associated with the emergence of novel concepts and is in general subject to a wider empirical clissification scheme than the reducing theory. The implications of these results for reductionism, holism, emergence, and their conceptual unification are discussed.


An assay for plasma somatomedin: [3H]thymidine incorporation by isolated rabbit chondrocytes. The incorporation of [3H]thymidine by rabbit chondrocytes in vitro has been developed as a sensitive assay for plasma somatomedin. A concentration of normal plasma of 2-5% enhanced [3H]thymidine incorporation by 5- to 20-fold compared with basal levels in the absence of plasma. The mean potency of plasma from normal adult men was 0-96+/-0-1 u./ml (mean+/-S.D.) and from acromegalic patients 1-9+/-0-4 u./ml. The apparent potency of hypopituitary plasma alone increased on heating which suggested the presence of heat-labile inhibitors of somatomedin activity. The potency of heated hypopituitary plasma (0-6+/-0-09 u./ml) remained significantly lower (P less than 0-01) than normal plasma. Human growth hormone (0-1-20 muu./ml), bovine growth hormone (0-5 20 muu./ml), insulin (0-5-5 muu./ml) and glucose (0-3-2 mmol/1) had no direct effect on the incorporation of [3H]thymidine. Chondrocytes which had been previously stored frozen also showed a response to plasma somatomedin.


Effects of protein synthesis inhibitors on angiotensin-stimulated and angiotensin-inhibited fluid transport by rat jejunum in vivo. A study has been made of the effects of protein synthesis inhibitors on the responses of rat jejunum in vivo to intravenous infusions of angiotensin. Actinomycin D, an inhibitor of the transcription stage of protein synthesis, was without effect on the stimulation of fluid transport which follows the infusion of low doses of angiotensin. Cycloheximide, an inhibitor of the translation stage of protein synthesis, blocked the stimulatory response to angiotensin, but was without effect on the inhibitory response to high doses of the hormone. It is concluded that low (physiological) doses of angiotensin stimulate fluid transport by a mechanism involving protein synthesis at a stage later than transcription whereas high doses of the hormone inhibit fluid transport by a process which does not require protein synthesis.


Actions of growth hormone, prolactin and thyroxine on serum somatomedin-like activity and growth in hypopituitary dwarf mice. Hypopituitary dwarf mice (Snell's strain) were found to have much reduced levels of serum somatomedin when compared with normal mice (apparently normal members of the Snell strain). Treatment with bovine growth hormone, prolactin or thyroxine induced growth in these animals; this was accompanied in each case by increased levels of serum somatomedin (primarily somatomedin C). Growth hormone had a dose-dependent growth-promoting effect, but this was not reflected in dose-dependent increases in serum somatomedin levels. These results are in accordance with the concept that somatomedin is involved in the regulation of overall somatic growth, but it seems likely that other factors are also involved.


Influence of restraint on plasma prolactin and corticosterone in female rats. The effect of restraint on plasma prolactin and corticosterone concentrations was investigated in chronically catheterized, ovariectomized (OVX) or ovariectomized, oestrogen-treated (OVX-PEP) rats. Restraint was induced by tying the hind legs together. In OVX rats, prolactin levels were unchanged following restraint, either during the morning (10.00 h) or afternoon (14.00 h). Prolactin levels increased in OVX-PEP animals when restraint was initiated in the morning; when restraint was initiated in the afternoon the prolactin response depended upon the level of prolactin before restraint. If levels were low (pre-surge) the response to restraint was similar to that observed in the morning; if prolactin levels were high (surge) the response to restraint was reversed and the prolactin level declined. The morning prolactin response to restraint was significantly inhibited and the afternoon surge was retarded in adrenalectomized OVX-PEP (OVX-PEP-ADX) rats; however, in OVX-PEP animals maintained on 0-9% NaCl drinking solution, the morning prolactin response to restraint was also blunted, although the afternoon surge was normal. In OVX-PEP-ADX animals injected with either vehicle alone, or 2 or 4 mg corticosterone for 4 days, and sampled on the morning of day 5, the prolactin response to restraint was absent. Furthermore, when OVX-PEP animals were injected daily with either vehicle or 4 mg corticosterone/day, they showed no increase in prolactin in response to restraint when values were compared with those of uninjected animals. Corticosterone levels after restraint were higher than initial values in all of the above experimental conditions.


The role of neurosecretion in the photoperiodic control of polymorphism in the aphid Megoura viciae. The location of the photoperiodic mechanism controlling the production of the sexual and parthenogenetic morphs by apterous parents was examined by selectively injuring the brain with an R.F. microcautery. Lesions destroying the Group I neurosecretory cells (NSC) in the protocerebrum abolished the response to changed daylength. Extensive damage to other NSC Groups, to the compound eyes and optic lobes was without effect. It is concluded that the Group I NSC are the effectors, secreting a virginoparapromoting substance; in its absence only oviparae are produced. Areas slightly lateral to the group I NSC are also required for the long-day response, indicating that this is the probable site of the neuronal photoperiodic clock which regulates the release of neurosecretory material (NSM) from the Group I cells.


Body weight and the haematology of the american plaice Hippoglossoides platessoides. The relationship between haematological variables and body weight (W) is studied in the American plaice. Haematocrit, haemoglobin concentration, and cell volume and numbers are directly correlated with W, indicating that small fish have low blood oxygen solubility (alphaBO2) in spite of a high weight specific oxygen consumption (VO2/W). Examination of analytical models of the branchial apparatus suggests that, in small fish, alphaBO2 is lowered to minimize blood viscosity and that a high VO2/W is maintained by increasing the arteriovenous oxygen partial pressure difference. Mean cell haemoglobin content is positively correlated while mean cell surface area per unit haemoglobin tends to be negatively correlated with W. Mean erythrocyte residence time in the secondary lamellae is shown analytically to increase with W, possibly accounting for these relationships.


Asymmetrical permeability of the integument of tree frogs (Hylidae). The skin from four species of North American tree frogs (Hylidae) was found in vitro, to be remarkably permeable to water in the presence or absence of the neurohypophysial hormone vasotocin. This property was, however, only seen in preparations from the ventral integument; osmotic water movement across the dorsal skin was negligible. The ionic permeability, reflected by the electrical resistance, was also much greater in the ventral skin. Unidirectional fluxes of 22Na, 36Cl, 14C-urea and tritiated water were measured in vitro in a single species, Agalychnis dacnicolor Cope. The ventral skin was 10-20 times more permeable to these molecules than the dorsal skin. The short-circuit current (usually reflecting active transmural Na transport) across the ventral skin was increased by aldosterone and vasotocin but these responses were absent on the dorsal side. The lipid content of the dorsal skin was four times greater than that on the ventral surface.


Ionic basis of axonal excitability in an extreme euryhaline osmoconformer, the serpulid worm Mercierella enigmatica (Fauvel). Despite the extreme fluctuations in blood concentration experienced by this marine osmoconformer, essentially 'conventional' ionic mechanisms are involved in conduction by the giant axons in isosmotic conditions. The resting axonal membrane approximates to an ideal potassium electrode, with a 58-8 mV slope for decade change in [K+]O above 10 mM. The action potential overshoot shows a 55-8 mV decline with decade reduction in [Na+]O and the action potentials are blocked by tetrodotoxin at around 5 X 10(-7) M. The rising phase and overshoot of the action potential remain constant at potassium concentrations up to the relatively high level of 30 mM found in the blood, indicating an unusual absence of sodium inactivation over a wide range of resting potentials. Relatively rapid, symmetrical movement of potassium ions between the bathing medium and the axon surface is deduced from the potential changes induced by alterations in [K+]O. Outward movement of sodium ions (t0-5 = 33-5 s) occurs at a similar rate to that of potassium, but inward movement of Na+ is relatively slow and complex. It is concluded that the ability of axons to function in dilute media must involve specific adaptations to osmotic and ionic stress.


Behavioural thresholds for diffuse illumination in the goldfish. Thresholds for diffuse, broad-band illumination were obtained for the goldfish (Carassius auratus) by avoidance conditioning. The light source was a television cathode-ray tube whose output was controlled over a range of 140 dB by a combination of 'brightness' control, blanking of scan lines, and neutral density filters. The threshold was calculated in terms of irradiance to be 2-9 X 10(-6) muW cm-2 (+/- a standard deviation of 1-4). The determination of absolute, rather than relative, values, and the use of overhead, diffuse illumination provided data that would be ecologically and behaviourally relevant.


Mechanisms for directional hearing in the sea catfish (Arius felis). The marine catfish (Arius felis) uses directional hearing for the acoustical detection of obstacles, and is primarily dependent on the vector components of near-field acoustics. Directional sound, detected as lateral line action potentials, produces the strongest response on the side toward the stimulus. Responses are maximal in the 50-150 Hz range. The swim bladder is asymmetrical as a sound generator (7 dB front-to-back ratio). As a sound receiver, the swim bladder is even more directional (24 dB front-to-back ratio at 100 Hz). It is concluded that directional response to sound in fishes can involve the interaction of at least two mechanisms, in this case the lateral line and the swim bladder.


Bursting pacemaker activity in the solitary hydroid Tubularia solitaria. Spontaneous electrical activity recorded from solitary Tubularia solitaria Warren consisted of long bursts of potentials regularly alternating with series of short bursts. Hydranth pulse (HP) systems in isolated hydranths produce a pulse pattern similar to that in intact animals though at a much lower frequency. Stalk pulse (SP) systems in isolated stalks produced extremely regular bursts of pulses resembling bursting patterns in molluscan single neurones. The bursts were associated with strong bending movements. In contrast with hierarchies in other hydroids, T. solitaria's HP system dominates the SP system. Excised parts of the stalk produced bursting patterns. Interburst- and interpulse intervals were longer in these parts than in the whole stalk. Numbers of pulses per burst and overall pulse frequency were highest in the most distal part of the stalk, and lowest in the most proximal part.


Urine production rate and water balance in the terrestrial crabs Gecarcinus lateralis and Cardisoma guanhumi. 1. The rate of urine production in the terrestrial crabs Gecarcinus lateralis (Freminville) and Cardisoma guanhumi Latreille maintained on s.w.-moist sand was measured by inulin clearance. 2. The inulin U/B ratios in both species rose to about unity after 48 h, and remained at this level. It was concluded that neither species withdrew water from the primary urine. 3. The relatively high rate of inulin clearance in G. lateralis (10-69% body wt day-1) was considerably reduced when animals were transferred to dry sand (2-15% body wt day-1). 4. The rate of water loss on dry sand was measured in G. lateralis and changes in the haemolymph and urine osmolality recorded. 5. The prevention of possible reabsorption of water from voided urine did not appear to affect significantly the rate of water loss in conditions of water deprivation. 6. The maintenance of urine production rates measured on s.w.-moist sand would double the water loss of G. lateralis in dry conditions.


In vitro granulocyte adherence and in vivo margination: two associated complement-dependent functions. Studies based on the acute neutropenia of filtration leukophoresis. To study mechanisms and mediators regulating the distribution of intravascular granulocytes between circulating and marginated pools, a human model with extreme transient margination, the neutropenia of continuous flow filtration leukophoresis, was analyzed. Studies in animals demonstrated the existence of a complement (C)-derived granulocytopenia-inducing factor. Thus, autologous plasma, exposed to nylon fibers (NF) of the filtration system, produced an acute selective decrement of circulating granulocytes and monocytes. This phenomenon was blocked by decomplementing plasma, by pretreatment of plasma with EDTA or hydrazine, and by preheating at 56 degrees C, but did occur after recombination of heat-inactivated and hydrazine-treated plasma before NF exposure. Preheating plasma at 50 degrees C did not inhibit the neutropenic response, suggesting involvement of the classical pathway of C activation. Ultrafiltration studies indicated that the NF-provoked neutropenia-inducing factor has a mol wt in the range of 10,000-30,000, and is heat stable (56 degrees C). To analyze the hypothesis that C- induced neutrophil margination might be consequent to increased cell adhesiveness to endothelial surfaces, the role of C in promoting granulocyte adherence was evaluated in vitro. Measured with a plastic Petridish assay, granulocyte adherence was significantly reduced in heat- inactivated (56 degrees C) and hydrazine-treated plasma, but adherence promoting capacity was restored by mixing the two plasmas, or by adding purified C3 to hydrazine-treated plasma. After exposure to activated C, neutrophils showed significantly increased adhesiveness which was maintained when cells were resuspended in heat-inactivated plasma, but progressively lost when resuspended in fresh plasma. On the basis of these results we conclude that granulocyte adhesiveness in vitro and margination in vivo are closely associated, C-dependent phenomena.


The ingestion and digestion of human lactoferrin by mouse peritoneal macrophages and the transfer of its iron into ferritin. Human lactoferrin (Lf) labeled with 125I and/or 59Fe was found to be ingested in vitro by mouse peritoneal macrophages (MPM). The uptake measured after 15 h incubation reached a saturation point at a concentration of 200 microgram/ml in the culture medium, whatever was the iron content of Lf. In such conditions, the uptake of transferrin (Tf) used as a control was 10 times lower. At a concentration of 80 microgram/ml in the medium, one cell picked up about 0.7 X 10(6) molecules of Lf per hour, and 0.13 X 10(6) molecules of Tf per hour. Iron-saturated Lf disappeared from MPM with a half life of 14.5 h, whereas the halflife of iron-free Lf was 4.2 h. Concomitant with the intracellular digestion of Lf, the iron was transmitted to ferritin. These data provide additional support for the hypothesis that Lf plays a key role in iron turnover, especially at the level of the reticuloendothelial system where iron is recovered from the catabolism of erythrocytes.


Autoimmunity to type II collagen an experimental model of arthritis. We have found that intradermal injection of native type II collagen extracted from human, chick or rat cartilage induces an inflammatory arthritis in approximately 40% of rats of several strains whether complete Freund's adjuvant or incomplete Freund's adjuvant is used. Type I or III collagen extracted from skin, cartilage proteoglycans and alpha1(II) chains were incapable of eliciting arthritis, as was type II collagen injected without adjuvant. The disease is a chronic proliferative synovitis, resembling adjuvant arthritis in rats and rheumatoid arthritis in humans. Native type II co-lagen modified by limited pepsin digestion still produces arthritis, suggesting that type-specific determinants residing in the helical region of the molecule are responsible for the induction of disease. Since homologous type II collagen emulsified in oil without bacterial preparations regularly causes the disease, this new animal model of arthritis represents a unique example of experimentally-inducible autoimmunity to a tissue component.


Release from maternally-induced allotypic suppression in rabbit by Nocardia water-soluble mitogen. The in vitro synthesis of allotypes of b4/b5 offspring obtained from b4/b4 mothers immunized against paternal allotype b5/b5 was studied in comparison to similar offspring that had escaped from suppression and normal heterozygous b4/b5 rabbits. Nocardia water-soluble mitogen-a rabbit B-cell mitogen which is known to induce the differentiation of small lymphocytes into plasma cells and polyclonal activation of Ig, was able to break in vitro the allotypic suppression induced in vivo.


Purificaiton and characterization of mouse serum protein with specific binding affinity for C4 (Ss protein). A new component of the complement (C).system, with a specific binding affinity for the activated Ss-protein (C4) has been identified in mouse serum. This protein, named Ss- (or C4)-binding protein (Ss-bp), was purified about 200 times from mouse plasma. Ss-bp is a heat stable (56 degrees C, 60 rain) beta-globulin with a sedimentation coefficient in sucrose density ultracentrifugation of 10s. Its concentration in serum of adult male and female mice is 160 and 60 mug/ml, respectively. In EDTA-plasma, Ss and Ss-bp are not associated and can be separated by chromatography in Sephadex G-200. However, in serum Ss-bp binds tightly to Ss. The bonds between these proteins cannot be reversed by chelation of divalent cations. As a consequence of the formation of Ss/Ss-bp complexes, the properties of Ss-bp appear to be quite different in serum of mice with high (Ss-H) or low (Ss-L) levels of Ss-protein. In Ss-H serum, all of Ss- bp is bound to Ss. In Ss-L serum, Ss-bp is mostly free. Because the electrophoretic mobilities of free and complexed Ss-bp are quite different, Ss-bp appears to be polymorphic in serum (but not in EDTA- plasma). The strict dependency of the apparent electrophoretic mobility of Ss-bp on the levels of Ss in serum was demonstrated in a series of congenic mice and among the progeny of a cross between Ss-H and Ss-L strains of mice. Without exception, the slow and fast varieties of Ss-bp were associated with the Ss-L and Ss-H traits. Ss-bp of the slow variety can be transformed into the fast variety by addition of pure human C4, or C4-sufficient guinea pig serum, to Ss-L serum. In both instances Ss-bp formed stable complexes with C4 or a C4- derived peptide. These findings highlight the binding specificity of Ss- bp for the fourth component of the complement system, and in addition they demonstrate a functional homology between the Ss-protein and C4 from two different species.


Some factors affecting a commercial kit for radioimmunoassay of digoxin using tritiated digoxin. Some factors affecting results of digoxin determinations using one commercially available radioimmunoassay kit are described and discussed. Serum of pregnant women, cord blood, amniotic fluid and serum of patients taking spironolactone may show erroneously high digoxin activity due to lack of specificity of the antiserum. Cross-reaction with digitoxin was found to vary substantially with antibody-lot. Haemaccel (5 g/1) in the sample leads to too low results. When ethanol (100 g/1) is present results are too high. The need for testing the specifity of every new lot of antiserum before use is stressed.


Thin-layer chromatography of guanidino compounds. Twelve guanidino compounds including, among others, glycocyamine, creatine, creatinine, arginine, guanidinosuccinic acid were submitted to thin-layer chromatography on plates precoated with silica gel or cellulose, respectively. Optimal resolution was obtained by two-dimensional chromatography on cellulose layers when the two solvent systems iso-propanol-acetic acid-water (volumes, 60 ml + 45 ml + 15 ml) and iso-propanol-dimethyl-formamide-water (volumes, 40 ml + 20 ml + 20 ml) were used for the first and second dimension, respectively. This procedure permitted the resolution of 10 distinct spots out of a mixture of the twelve guanidino compounds. Chloroform-methanol-ammonia (170 g/kg) (volumes, 40 ml + 20 ml + 20 ml) proved to be the most suitable solvent system for one-dimensional chromatography on cellulose layers of less complex mixtures of guanidino compounds.


A discrete multichanneal procedure for the chemical determination of urinary estrogens during pregnancy. A colorimetric method, based on the Kober reaction, was adapted for the determination of urinary estrogens during pregnancy. The method yields final volumes for direct measurements by a multichannel computer-controlled photometer. The speed of the analysis was increased so that 100 samples can easily be completed by one laboratory technician as triplicate analyses during one working day. A satisfactory accuracy and precision of the method were also achieved. The values were determined using urine samples from 1097 apparently healthy pregnant women.


Pyridoxal 5'-phosphate as an activator of the apoenzyme of alanine aminotransferase in human serum. The relationship between reaction conditions and the stimulation of alanine aminotransferase by pyridoxal 5'-phosphate was investigated. Reaction conditions given for optimized alanine aminotransferase measurements are also optimal for measurements in the presence of pyridoxal 5'-phosphate taking into consideration the inhibitory effect of phosphate buffer. Addition of 150 mumol/1 pyridoxal 5'-phosphate to the reaction mixture guarantees a maximal stimulation after a pre-incubation period of 10 min. Factors influencing the magnitude of stimulation rates of both aminotransferases in different patient groups by pyridoxal 5'-phosphate are discussed.


Quantitative determination of glycosphingolipids in human plasma. A method is described for the quantitative isolation and estimation of the four glycosphingolipid fractions from 10 ml of human plasma. The procedure consists of acetylation of the total lipids after extraction, separation of acetylated glycophingolipids from non-glycolipids on a Florisil column, deacetylation, dialysis in water, separation of the single fractions by thin-layer chromatography on silica gel, and quantitative analysis of each glycosphingolipid by sulfuric acid-orcinol reagent, carried out in the presence of silica gel. The concentrations of the four glycosphingolipids in human plasma derived from a group of 23 healthy subjects are presented. The procedure described is sufficiently sensitive for clinical investigation.


Evaluation of and additional data on an improved simple charcoal method to determine oestrogen receptors. Additional information and some modifications of an earlier published method ((1972) Z. Klin. Chem. Klin. Biochem., 10, 502-508) for the assay of oestrogen receptor in human breast tumours are presented. The correlation between the results obtained with this method and with the electrophoresis procedure of Wagner ((1972) Hopper Seyler's Z. Physiol. Chem., 353, 1235-1245) was found to be good. The use of glycerol stabilized calf uterus extract for quality control is proposed. Various factors affecting the assay and the discrimination between receptor positive and receptor negative are critically discussed.


[Determination of total urinary porphyrins by derivative spectroscopy (author's transl)]. The principle of derivative spectroscopy is the basis of a new procedure for determining total urinary porphyrins. The 2nd derivative of the normal spectrum isolates the Score band of the porphyrins from the background absorption and enables the quantitative evaluation without correction factors. The new procedure is more sensitive than the classical method using measurement at three wavelengths and permits reliable determinations in the normal range. The short analysis time and the low reagent requirement allow economic screening. Normal and slightly increased contents of total urinary porphyrins can be reliably determined in undiluted urine samples up to 0.16 mumol/1. A dilution is required for higher concentrations. The sensitivity for 0.01 mumol/1 total porphyrins in urine is 0.06 absorbance units. The coefficient of variation for the series determination of samples with 0.07 mumol/1 is about 1%.


[Effect of immersion on the urinary excretion of aldosterone in trained and untrained male subjects (author's transl)]. Diuresis, the excretion of aldosterone-18-glucuronide and the excretion of sodium and potassium were measured before and during two periods of immersion in four male athletes in training and four untrained male subjects (age 20-27 years). The increase in diuresis during immersion was accompained by a concomitant decrease of aldosterone excretion and increase of sodium excretion in urine. These changes were more pronounced in untrained subjects than in trained subjects. From these results it may be concluded that trained subjects react more sensitive to slight changes in aldosterone secretion than untrained subjects.


[Sex specific action of insulin on the glucose metabolism of lymphatic tissue of rats and humans (author's transl)]. Glucose metabolism of lymphoid cells isolated from thymus and spleen of Wistar rats, weighing 140-150 g, was found to be sensitive to insulin. The influence of insulin on glucose uptake by isolated cells from both lymphoid tissues displayed a significant sex specificity. Insulin at 0.1-10 nmol/1 stimulated glucose uptake of cells from male rats, whereas in cells from females, inhibition of glucose uptake was observed. However, lactate production was enhanced in lymphoid cells of both sexes. Cortisol (100 nmol/1) displayed a significant anti-insulin action on glucose uptake and lactate release by thymocytes of male rats. In contrast, in cells from females, cortisol and insulin both exhibited an inhibitory action on glucose uptake, whereas the hormones were found to antagonise lactate production. The sex specific stimualtory influence of insulin on glucose uptake by thymocytes of male rats was reversed and the hormone became inhibitory when animals were castrated. The action of insulin on glucose uptake was also shown to be age-dependent. In experiments with rats weighing either about 10 g or 40 g, sex-specific effects on glucose influx were found, that were similar to those of rats weighing 140-150 g. However, stimulation of glucose uptake was found with thymocytes from rats of both sexes weighing about 80 g. Comparable results were obtained with isolated thymocytes from immature humans (2 months-10 years old). Incubation of thymocytes from males with insulin (10 nmol/1) stimulated glucose uptake and lactate release, whereas insulin caused an inhibition of glucose uptake and an enhancement of lactate production in thymocytes from female. Age dependence and sex specificity of insulin action on glucose metabolism in lymphoid cells and tissues may explain the contradictory results reported by other authors.


Distribution of oestradiol receptor molecules in human kidney. Experiments were performed to determine the distribution of oestrogen receptors in normal human kidney. Cytosols prepared from renal medulla and cortex were separately analyzed for oestrogen receptor molecules aga gel electrophoresis. Oestrogen receptors could be demonstrated in both compartments of the organ. However, the experiments reveal that the medulla is the main locus of oestrogen receptor in human kidney.


A simplified micromethod for the determination of the acetylator phenotype. A simplified and rapid method is described for phenotyping of sulfamethazine acetylation. Two hours after a test dose of sulfamethazine, free and total sulfamethazine are estimated in blood drawn either by capillary or venipuncture. The present method offers sharp segregation between slow and rapid acetylators, requires micro blood volumes drawn from finger- or ear pucture, and is more convenient for population genetics survey as well as for clinical investigations.


[Analysis of urinary proteins by disc electrophoresis: a method for the differential diagnosis of kidney diseases (author's transl)]. After introductory observations on the role of the kidney in protein metabolism, the methodology and results of disc electrophoresis on polyacrylamide, using detergents, are discussed. Separation of urinary proteins according to molecular weight permits the differentiation of kidney diseases into those of the glomerulus and of the tubules. Proteinurias of prerenal and postrenal origin are also differentiated. Owing to the considerable time involved, this methodology cannot at present be introduced for routine purposes.


[Simplified titrimetric semimicrodetermination of lipase in serum (author's transl)]. The quantitative, titrimetric and kinetic method for the determination of lipase in serum, duodenal juice and punctures by Rick (Rick, W. (1969), this journal 7,530-539) has been adapted as a routine semimicro-method using 0.20 ml volume of spcimen without N2 protection. The description of the procedure and quality control data are reported. The method has been checked for more than 3 years and sera from more than 3000 patients have been investigated.


[Studies of the interractions of cyclamate with phenprocomon (author's transl)]. The effect of cyclamate on the anticoagulant activity of phenprocoumon was investigated in rats after single oral doses of phenprocoumon, cyclamate, or phenprocoumon/cyclamate. By means of high pressure liquid chromatrography [HPLC] the change of the concentration of phenprocoumon per unit time in sera was determined. The anticoagulant acitivity of phenprocoumon was determined by the extension of the prothromin-time (Quick-test). It was found that cyclamate gives rise to an elevated of phenprocoumon in the blood, and a reduction of the anticoagulanting potency.


[Isoenzymes of creatine kinase in the perinatal period (author's transl)]. The serum of new-born children shows a higher catalytic concentration of creatine kinase than adult serum. These values reach normal adult levels within the first 10 days of life. In addition to the MM-, the MB- and BB-isoenzymes of creatine kinase are also found in the serum of women in labour, in cord-serum, and in the serum of newborn children. These findings should be taken into consideration in the analysis of creatine kinase isoenzymes.


Demonstration of a collagenolytic enzyme in postmortal human colon tissue. A collagenolytic enzyme was extracted from the 6000 g sediment of homogenized postmortal human colon tissue. The enzyme digests native collagen at neutral pH. The enzyme has been concentrated by ammonium sulfate precipitation. The collagenolytic activity was measured using [1-14C]acetylated calf skin collagen, solubilized in 0.1 g/1 acetic acid. There was a significant inactivation of the enzyme solution after the addition of mumol EDTA to the test volume.


An experimental model for studies on the effects of food and digestive secretions on the digestive-absorptive capacity of rat small intestine. At an average of 32 days after a modified Roux-en-y repositioning of rat small intestine, the mucosal mass, mucosal composition, in vivo absorption of galactose and the activity of maltase, sucrase and alkaline phosphatase were measured. In the gut segment with digestive secretions but without food (A) the only change was a decrease of sucrase activity which occurred most probably at the cellular level. In the gut segment with food and gastric juice and a reflux of digestive secretions (B) complex changes took place. An increase in mucosal mass was not accompanied by an increase in galactose absorption. There was a high increase of sucrase activity, a moderate increase of maltase activity and a tendency of the alkaline phosphatase activity to decrease. The changes (increase in mucosal mass and total enzyme activity, but no changes in activity at the cellular level) in the segment exposed to both digestive secretions and food (C) were compatible with a more proximal promotion of a distal gut segment.


[A rapid semiautomatic separation of urinary catecholamines (author's transl)]. The semiautomatic separation of the catecholamines, adrenaline and noradrenaline, is based on their adsorption onto aluminium oxide at pH 8.4, followed by batch elution with 0.05 mol/1 perchloric acid. The separate steps of the operation were investigated and optimised. Advantages of the method, compared with the manual column technique, are decreased time of operation, less involvement of personel, less danger of carry-over of interfering substances, and an exact standardisation of the processing time.


[Effect of spirolactones on the urinary excretion of individual 17-oxosteroids and of pregnanediol in man (author's transl)]. The effect of spirolactones on the urinary excretion of individual 17-oxosteroids and of pregnanediol in man was investigated under various conditions. After purification by thin-layer chromatography, the 17-oxosteroids and pregnanediol were determined by gas chromatography. Eleven male subjects (age 21-34 years) received a daily dose of 200 mg spironolactone (Aldactone) orally on seven consecutive days. Five female subjects (age 20-35 years) and ten pregnant women (age 20-35 years; 28th.-39th. week of gestation) were given a daily intravenous injection of 600 mg potassium canrenoate (Aldactone pro injectione) on three consecutive days. In the male subjects, the excretion of individual 17-oxosteroids and of pregnanediol was significantly reduced during administration of spironolactone. In the nonpregnant female subjects, the excretion of etiocholanolone and dehydroepiandrosterone was diminished, whereas in the pregnant women, the excretion of pregnanediol and dehydroepiandrosterone was decreased during treatment with potassium canrenoate. These results suggest that the reduced urinary excretion of steroids may be due to an inhibition of steroid metabolising enzymes by spirolactones. It seems likely that spirolactones affect the enzymatic conversion fo cholesterol to pregnenolone.


A simple, rapid and accurate screening test for hyperchlororhoea. A simple, rapid screening paper test for the quantitative estimation of Cl- concentration in feces is described. The measured time of decolorisation of the Chlorotrex indicator by aqueous extract of feces is inversely proportional to the chloride concentration. The technical details of the test are given. The test is very suitable for laboratory and mass screening.


Whole salivary immunoglobulin levels in 60 healthy children: determined by a sensitive electroimmuno technique after prior carbamylation. Immunoglobulins in whole saliva, collected unstimulated from 60 healthy children, 4 to 15 years of age, were determined by a modified electroimmuno technique using carbamylation of the samples prior to electrophoresis. This technique, which is generally used for measurement of immunoglobulins in serum, was found to be rapid, precise, and sensitive. The mean (median) for salivary IgA was 5.1 kIU/1, which was significantly higher than values obtained from stimulated or unstimulated parotid saliva by other investigators. The mean value for salivary IgG was 120 IU/1. IgM in saliva was only found in measurable amounts in 5 children.


[Plasminogen content of human fibrinogen preparations from different sources (author's transl)]. In connection with fibrinolytic therapy, it is of interest to know how much plasminogen is contained in different commercially available figrinogen preparations. This problem was investigated with the aid of a semiquantitative determination of plasminogen. The determined plasminogen content was compared with plasminogen concentration of pooled human plasma. Using the ratio of plasminogen to fibrinogen, and fixing the plasminogen content of human plasma arbitrarily at 100%, the proportion of plasminogen in fibrinogen from Immuno is 134%, fibrinogen from Behringwerke contains 13.7%, and Kabi-fibrinogen contains 2.71% plasminogen.


[Influence of heparin therapy on the determination of lipase in serum (author's transl)]. Following single doses of heparin and with continuous heparin infusion the activity of lipase in the serum increases temporarily and can attain pathological values also in healthy persons. Even when the heparin infusion is continued, the lipase values return after at the most 24 hours to the initial value before application of heparin. For a diagnosis of diseases of the pancreas the interpretation of lipase values in serum must consider how long the patient has been treated with heparin.


[Influence of testosterone on the distribution of 65Zn-binding proteins in the prostate and seminal vesicles of rats (author's transl)]. 65Zn (7.4 MBq: 200 muCi) was injected intravenously into normal, castrated and castrated, testosterone-substituted rats. After 1, 24 and 48 hours, the distribution of 65Zn-binding proteins in the 100,000 g supernatant of the prostate and seminal vesicles was investigated by separation on Sephadex G 100. The prostate and seminal vesicles from any one rat showed the same distribution pattern of 65Zn-proteins. In castrated rats, the incorporation of 65Zn was, however, 5-6 times lower than in the normal or castrated, testosterone-substituted rats. One hour after the injection, the highest activity of 65Zn was found in proteins in the molecular weight range above 100,000. After 48 hours the greatest proportion of 65Zn was present peak corresponding to 28,000 Daltons.


Warning signals and alerting: effects on differential classical conditioning. Three experiments were carried out to investigate the effects of a nondifferential warning signal on differential classical conditioning. In Experiment 1, a 500-msec warning interval was found to result in good differential conditioning performance at an interstimulus interval (ISI) of 500 msec in which differential conditioning did not otherwise occur. The second experiment demonstrated the warning effect with both visual and auditory conditioned stimuli, thus ruling out the possibility that the warning effects were due to eye movements. Experment 3 showed that a warning signal and an increased ISI were functionally equivalent, as demonstrated by conditioning performance and the similar effects obtained when the ISI and warning-interval conditions were switched from optimal to nonoptimal and vice versa.


Stimulus intensity effects in electrodermal habituation. Experiment 1 presented human subjects with 25 shocks of the same (.5, 1.5, or 2.5 mA:between-subjects design) or different (.5, 1.0, 1.5, 2.0, and 2.5 mA:within-subjects design) intensities to test predictions of the dual-process, cortical-model, and adaptation-level theories concerning terminal electrodermal response (EDR) magnitudes in an habituation paradigm. Dual-process theory correctly predicted terminal EDR magnitudes and relative EDR habituation rates. Dual-process theory was further supported in Experiment 3 when EDR magnitude to a standard intensity shock (1.25 mA) decreased with the intensity of a second comparison shock (0, .5, 1.25, or 2.5 mA) only up to the 1.25-mA level, as the common-elements construct of the dual-process theory predicts. Adaptation level incorrectly predicted that standard stimulus EDR magnitude would decrease as comparison intensity, hence adaptation level, increased. Forewarning subjects of each shock intensity increased EDR magnitude in Experiments 2 and 3 contrary to the cortical-model theory's prediction based on subjective stimulus uncertainty.


Effects of instruction on acquisition and extinction of electrodermal responses to fear-relevant stimuli. In the present study we examined the hypothesis that electrodermal responses conditioned to fear-relevant stimuli are insensitive to verbal instructions. In the first experiment, different groups of subjects were conditioned to fear-relevant and fear-irrelevant control stimuli in a long interstimulus interval differential paradigm with shock as the unconditioned stimulus. Then half of the subjects were informed that no more shocks would be presented, and a number of extinction trials followed. The instruction completely abolished responding to fear-irrelevant stimuli, while leaving responses to the fear-relevant stimuli unaffected. In the second experiment, subjects were "conditioned" to fear-relevant or irrelevant stimuli by an instruction involving threat of shock. This manipulation potentiated potentiated responses to fear-relevant stimuli significantly more than responses to fear-irrelevant stimuli. Thus, instruction had a symmetrical effect on acquisition and extinction to fear-irrelevant stimuli, whereas it facilitated acquisition but was ineffective in reducing responding to the other class of stimuli. These results are related to a preparedness theory, and their relevance for an understanding of phobias is discussed.


The clinical recognition of congestive heart failure. The recognition of early or mild congestive heart failure in the ambulatory patient is a common clinical challenge in everyday practice. Early diagnosis requires attention to symptoms, signs, and radiographic changes which may be minimal. This paper reviews basic pathophysiological principles involved in congestive heart failure and summarizes etiological factors which may cause or precipitate congestive heart failure. The symptoms, signs, and subtle radiological findings of early congestive heart failure are also described in some detail.


Clinical virology in family practice: epidemiological and clinical observations of an outbreak of Coxsackievirus B type 1 infection in a kibbutz. In the late summer and early fall of 1975, a febrile illness broke out in Kibbutz Tsorah, a communal settlement situated in the Jerusalem District, affecting 148 (33 percent) of its 446 members. Sickness was recorded in 107 (54 percent) of 198 children under 14 years of age and in 41 (17 percent) of the remaining 248 members of the kibbutz. In addition to fever, gastrointestinal and upper respiratory symptoms were predominant. Pleurodynia and myocarditis were also observed, but only in 11 (7 percent) and 5 (3 percent) patients, respectively, all adults. Coxsackievirus B type 1 was isolated from 20 (53 percent) of 38 stool specimens received. A fourfold or higher rise in titer of neutralizing antibody to one of the isolates was demonstrated in 52 (74 percent) of 70 paired sera. The epidemiologic and clinical aspects of the outbreak are discussed. The importance of correlating laboratory findings with clinical and epidemiologic observations and the importance of collaborating with the laboratory virologist in the daily practice of the family physician are stressed.


A rationale and method for the sexual history in family practice. The taking of a sexual history produces a therapeutic effect for the patient by giving the patient permission to be sexual, filling patient knowledge gaps, providing a reality check, and beginning the process of self-acceptance by the patient. The physician's own empathy may seem to interfere with his feeling comfortable while eliciting a sexual history; at the same time the patient may struggle with feelings of shame and embarrassment. The physician can alleviate patient discomfort by being accepting and empathetic, and by assuming the patient has thought, felt, and done everything in the sexual area. He can also help by beginning with general questions, avoiding "why" questions and jargon, and gently reporting inconsistencies.


The communication of information from physician to patient: a method for increasing patient retention and satisfaction. Patients are more satisfied with their physicians when they are given and retain more information about their illnesses. Whe an experimental group of patients was asked to restate what they had been told, followed by physician feedback, retention of the information was 83.5 percent compared to 60.8 percent in a control group in which this technique was not used. Patient satisfaction was also higher in the experimental group.


Early ambulatory experience in the undergraduate education of family physicians. A number of benefits have been claimed for early ambulatory experience in the training of family physicians, although few practical examples have been reported. This paper describes an approach to the education of first and second year medical students interested in family medicine which places heavy emphasis on community-based ambulatory care. During the first year, an elective introductory preceptorship permits students to participate in the office practice of a family physician in a limited role. Seminars are offered concurrently to provide integrating principles and perspective. In the second year, a nine-month-long continuity clerkship is offered in which students gain intimate contact with a small panel of families and practice the skills of primary care in the offices of family physicians. Clinical experience is accompanied by weekly seminars and integrated with elements of the required curriculum. Selected evaluation data are presented, which attest to the achievement of course objectives and provide support for the claim that this approach is beneficial to students seeking careers in primary care.


Guidelines for planning faculty development workshops. As departments of family medicine succeed in recruiting faculty members from the ranks of practicing physicians and from other clinical disciplines, they are faced with the problem of how to help these new members function comfortably and effectively in their new roles as teachers, administrators and academicians. This paper addresses part of this problem by reviewing the literature on faculty development through workshops. Consistent components of effective faculty development workshops are presented as guidelines for future workshop planners.


Research in the family practice residency program. Research activity in family practice is becoming increasingly important as the specialty matures past its initial organizational and developmental phase. Family practice residency programs are directly involved in the definition and implementation of modern concepts in family medicine and frequently have available the necessary tools and resources for substantive research of various types. These programs therefore have both the opportunity and responsibility to become actively involved in research. Significant contributions have already been made in this area by faculty and residents in a number of family practice residency programs. This paper provides an overview of research areas in family practice, presents some examples of research to date, and suggests some practical approaches to facilitate further research efforts in family practice residency programs.


The use of automated ambulatory medical records. An extensive survey of the uses of computerized automated ambulatory medical record systems has been conducted. The medical services provided which seem to offer the greatest benefits include: patient profiles which are a concise summary of a patient's medical status, patient surveillance to help in preventive care and management of chronic disease, data presentation by flow sheets and graphs, and data-base searches for audit, training, and research. The close integration of medical data with patient management and administrative services such as scheduling, registration, and financial systems, gives valuable utilization and practice information. Improvement in the billing and accounting process is in itself a most important benefit. In addition, the collection and analysis of medical data for health services research, quality of care audits, and training of future providers offers much potential. A number of innovative and economically viable computerized ambulatory record systems are currently operating.


An integrated medical record and data system for primary care. Part 4: Family information. The gathering of family information has numerous advantages in a family practice setting. Methods are described which not only allow description of family structure but permit identification of each individual family member and his/her relationship to the family as a unit. The value of filing individual medical records in family folders is detailed. A functional definition of family is established and certain health-related characteristics are given. Included is comparison of family size and socioeconomic status (SES) of a family practice with census information on the total county population. Health-seeking behavior of two-person families (couples or single-parent plus child) related to SES is presented as one of many applications of recorded family information, potential for future research into the effects of family structure on morbidity is discussed.


The phylogenetic distribution of red cell 2,3 diphosphoglycerate and its interaction with mammalian hemoglobins. In order to better understand the extent to which 2,3 diphosphoglycerate (DPG) contributes to red cell function in the mammals, we assayed DPG levels in blood from a taxonomically diverse set of 71 species representing 14 orders. In addition, for 66 species and 4 hemoglobin phenotypes of the sheep, the effect of DPG on oxygen affinity was measured by determining P 50 values for hemoglobin in the absence of DPG and at 0.2 mM and 1.0 mM concentrations. Most mammals had high levels of red cell DPG and phosphate-free hemoglobins with a relatively high oxygen affinity. In contrast, two taxonomically unrelated groups had both very low intra-erythrocytic DPG concentrations as well as hemoglobins of native low oxygen affinity that interacted weakly with DPG. This latter group includes the Feloidea (order Carnivora) and the Bovoidea (order Artiodactyla). The relationship between DPG concentration, hemoglobin oxygen affinity and the interaction of DPG with hemoglobin is treated quantitatively to provide a model of mammalian red cell function. This derived expression is compared with descriptive allometric equations for whole blood P 50 and is shown to provide statistically reasonable predictions.


Frequency characteristics in the visual system of Drosophila: genetic dissection of electroretinogram components. Various drosophila mutants were used to dissect the electroretinogram (ERG) frequency response into components of different origins. The ommochrome granules in the receptor cell body are known to migrate in response to light, limiting the amount of light entering the rhabdomere. Comparison between the ERG frequency responses of the wild type and the mutant lacking the ommochrome granules indicates that the pigment migration reduces the amplitude gain at frequencies below 0.5 Hz. The ERG of drosophila compound eyes consists of contributions from receptor cells and the second-order cells in the lamina. Mutants with defective laminae showed a high-frequency cutoff with a corner frequency of about 20 Hz, while in wild type the response peaked in that frequency region. These results suggest that the lamina contributes mainly to the high-frequency components of the ERG transfer function. The shot noise model (Dodge et al., 1968) has been tested in drosophila by comparing the frequency response of the superimposed on the intracellular receptor potential. The results are consistent with the hypothesis that the receptor potential consists of a summation of small discrete potentials (bumps). In a mutant in which the bumps exhibit latency dispersion in response to a dim flash, the receptor showed a poor high-frequency response, the corner frequency being lowered to about 1-2 Hz. The slope of the cutoff was approximately 20 dB/dec indicating that the latency dispersion in this mutant is the major limiting factor in temporal resolution. Light-evoked high frequency oscillations have been observed in the ERG of another mutant. The oscillation was found sharply turned to light flickering at about 55 Hz.


Metabolism of acetylcholine in the nervous system of Aplysia californica. IV. Studies of an identified cholinergic axon. [3H]Choline, injected directly into the major axon of the identified cholinergic neuron R2, was readily incorporated into [3H]acetylcholine. Its metabolic fate was similar to that of [3H]choline injected into the cell body of R2. Over the range injected, we found that the amounts of acetylcholine formed were proportional to the amounts injected; the synthetic capability was not exceeded even when 88 pmol of [3H]choline were injected into the axon. Newly synthesized acetylcholine moved within the axon with the kinetics expected of diffusion. We could not detect any selective orthograde or retrograde transport from the site of the injection. In contrast, as indicated by experiments with colchicine, 30% of the [3H]acetylcholine formed after intrasomatic injection was selectively exported from the cell body and transported along the axon. Most of the [3H]acetylcholine was recovered in the soluble fraction after both intra-axonal and intrasomatic injection of [3H]choline; only a small fraction was particulate. The significance of large amounts of soluble acetylcholine in R2 is uncertain, and some may occur physiologically. The concentrations of choline introduced by intraneuronal injection into both cell body and axon were, however, greater than those normally available to choline acetyltransferase in the cholinergic neuron; nevertheless, these large concentrations were efficiently converted into the transmitter. The synthetic capacity of the neuron supplied with injected choline may exceed the capacity of storage vesicles and of the axonal transport process.


Sodium efflux in Myxicola giant axons.

Sodium efflux in Myxicola giant axons. Several properties of the Na pump in giant axons from the marine annelid Myxicola infundibulum have been determined in an attempt to characterize this preparation for membrane transport studies. Both NaO and KO activated the Na pump of normal microinjected Myxicola axons. In this preparation, the KO activation was less and the NaO activation much greater than that found in the squid giant axon. However, when the intracellular ATP:ADP ratio of the Myxicola axon was elevated by injection of an extraneous phosphagen system, the K sensitivity of Na efflux increased to the magnitude characteristic of squid axons and the activating effect of NaO disappeared. Several axons were injected with Na2SO4 in order to determine the effect of elevated Nai on the Na efflux. Increasing Nai enhanced a component of Na efflux which was insensitive to ouabain and dependent on [Ca] in Na-free (Li) seawater. After subtracting the CaO-dependent fraction, Na efflux was related linearly to [Na]i in all solutions except in K-free (Li) seawater, where it appeared to reach saturation at high [Na]i.


Characterization of the ATP-dependent calcium efflux in dialyzed squid giant axons. The magnitude of the activating effect of ATP on the Ca efflux was explored at different [Ca++]i in squid axons previously exposed to cyanide seawater and internally dialyzed with a medium free of ATP and containing p-trifluoro methoxy carbonyl cyanide phenyl hydrazine. At the lowest [Ca++]i used (0.06 micron more than 95% of the Ca efflux depends on ATP. At high [Ca++]i (100 micron), 50-60% of the Ca efflux still depends on ATP. The apparant affinity constant for ATP was not significantly affected in the range of [Ca++]i from 0.06 to 1 micron. Axons dialyzed to reduce their internal magnesium failed to show the usual activation of the Ca efflux when the Tris or the sodium salt of ATP was used. Only in the presence of internal magnesium is ATP able to stimulate the Ca efflux. Nine naturally occurring high-energy phosphate compounds were ineffective in supporting calcium efflux. These compounds were: UTP, GTP, CTP, UDP, CDP, ADP, AMP, CAMP, and acetyl phosphate. The compounds 2' deoxy-ATP and the hydrolyzable analog alpha,beta-methylene ATP were able to activate the Ca efflux. The nonhydrolyzable analog beta,gamma-methylene ATP competes with ATP for the activating site, but is unable to activate the Ca efflux. The results are discussed in terms of the specificity of the nucleotide site responsible for the ATP-dependent Ca efflux.


Repetitive firing: a quantitative study of feedback in model encoders. Recognition of nonlinearities in the neuronal encoding of repetitive spike trains has generated a number of models to explain this behavior. Here we develop the mathematics and a set of tests for two such models: the leaky integrator and the variable-gamma model. Both of these are nearly sufficient to explain the dynamic behavior of a number of repetitively firing, sensory neurons. Model parameters can be related to possible underlying basic mechanisms. Summed and nonsummed, spike-locked negative feedback are examined in conjunction with the models. Transfer functions are formulated to predict responses to steady state, steps, and sinusoidally varying stimuli in which output data are the times of spike-train events only. An electrical analog model for the leaky integrator is tested to verify predicted responses. Curve fitting and parameter variation techniques are explored for the purpose of extracting basic model parameters from spike train data. Sinusoidal analysis of spike trains appear to be a very accurate method for determining spike-locked feedback parameters, and it is to a large extent a model independent method that may also be applied to neuronal responses.


Repetitive firing: quantitative analysis of encoder behavior of slowly adapting stretch receptor of crayfish and eccentric cell of Limulus. Techniques developed for determining summed encoder feedback in conjunction with the leaky integrator and variable-gamma models for repetitive firing are applied to spike train data obtained from the slowly adapting crustacean stretch receptor and the eccentric cell of Limulus. Input stimuli were intracellularly applied currents. Analysis of data from cells stringently selected by reproducibility criteria gave a consistent picture for the dynamics of repetitive firing. The variable-gamma model with appropriate summed feedback was most accurate for describing encoding behavior of both cell types. The leaky integrator model, while useful for determining summed feedback parameters, was inadequate to account for underlying mechanisms of encoder activity. For the stretch receptor, two summed feedback processes were detected: one had a short time constant; the other, a long one. Appropriate tests indicated that the short time constant effect was from an electrogenic sodium pump, and the same is presumed for the long time constant summed feedback. Both feedbacks show seasonal and/or species variations. Short hyperpolarizing pulses inhibited the feedback from the long time constant process. The eccentric cell also showed two summed feedback processes: one is due to self inhibition, the other is postulated to be a short time constant electrogenic sodium pump similar to that described in the stretch receptor.


On the inhibition of muscle membrane chloride conductance by aromatic carboxylic acids. 25 aromatic carboxylic acids which are analogs of benzoic acid were tested in the rat diaphragm preparation for effects on chloride conductance (G(Cl)). Of the 25, 19 were shown to reduce membrane G(Cl) with little effect on other membrane parameters, although their apparent K(i) varied widely. This inhibition was reversible if exposure times were not prolonged. The most effective analog studied was anthracene-9-COOH (9-AC; K(i) = 1.1 x 10(-5) M). Active analogs produced concentration-dependent inhibition of a type consistent with interaction at a single site or group of sites having similar binding affinities, although a correlation could also be shown between lipophilicity and K(i). Structure-activity analysis indicated that hydrophobic ring substitution usually increased inhibitory activity while para polar substitutions reduced effectiveness. These compounds do not appear to inhibit G(Cl) by altering membrane surface charge and the inhibition produced is not voltage dependent. Qualitative characteristics of the I-V relationship for Cl(-) current are not altered. Conductance to all anions is not uniformly altered by these acids as would be expected from steric occlusion of a common channel. Concentrations of 9-AC reducing G(Cl) by more than 90 percent resulted in slight augmentation of G(I). The complete conductance sequence obtained at high levels of 9-AC was the reverse of that obtained under control conditions. Permeability sequences underwent progressive changes with increasing 9-AC concentration and ultimately inverted at high levels of the analog. Aromatic carboxylic acids appear to inhibit G(Cl) by binding to a specific intramembrane site and altering the selectivity sequence of the membrane anion channel.


Delayed rectification in the transverse tubules: origin of the late after-potential in frog skeletal muscle. Tetanic stimulation of skeletal muscle fibers elicits a train of spikes followed by a long-lasting depolarization called the late after-potential (LAP). We have conducted experiments to determine the origin of the LAP. Isolated single muscle fibers were treated with a high potassium solution (5 mM or 10 mM K) followed by a sudden reduction of potassium concentration to 2.5 mM. This procedure produced a slow repolarization (K repolarization), which reflects a diffusional outflow of potassium from inside the lumen of the transverse tubular system (T system). Tetanic stimulation was then applied to the same fiber and the LAP was recorded. The time courses of K repolarization and LAP decay were compared and found to be roughly the same. This approximate equality held under various conditions that changed the time courses of both events over a wide range. Both K repolarization and the LAP became slower as fiber radius increased. These results suggest that LAP decay and K repolarization represent the same process. Thus, we conclude that the LAP is caused by potassium accumulation in the T system. A consequence of this conclusion is that delayed rectification channels exist in the T system. A rough estimation suggests that the density of delayed rectification channels is less in the T system than in the surface membrane.


Effect of acetylcholine on postjunctional membrane permeability in eel electroplaque. Acetylcholine (ACh) was applied iontophoretically to the innervated face of isolated eel electroplaques while the membrane potential was being recorded intracellularly. At the resting potential (about -85 mV) application of the drug produced depolarizations (ACh potentials) of 20 mV or more which became smaller when the membrane was depolarized and reversed in polarity at about zero membrane potential. The reversal potential shifted in the negative direction when external Na+ was partially replaced by glucosamine. Increasing external K+ caused a shift of reversal potential in the positive direction. It was concluded that ACh increased the permeability of the postjunctional membrane to both ions. Replacement of Cl- by propionate had no effect on the reversal potential. In Na+-free solution containing glucosamine the reversal potential was positive to the resting potential, suggesting that ACh increased the permeability to glucosamine. Addition of Ca++ resulted in a still more positive reversal potential, indicating an increased permeability to Ca++ as well. Analysis of the results indicated that the increases in permeability of the postjunctional membrane to K+, Na+, Ca++, and glucosamine were in the ratios of approximately 1.0:0.9:0.7:0.2, respectively. With these permeability ratios, all of the observed shifts in reversal potential with changes in external ionic composition were predicted accurately by the constant field equation.


Biosynthesis, processing, and control of release of melanotropic peptides in the neurointermediate lobe of Xenopus laevis. The neurointermediate lobes of dark-adapted toads Xenopus laevis were incubated for 30 min in [3H]arginine and then "chased" for various time periods. By use of this pulse-chase paradigm there were detected 10 trichloroacetic acid (TCA)-precipitable peptides separated on acid-urea polyacrylamide gels and one TCA-soluble peptide separated by high-voltage electrophoresis (pH 4.9) with melanotropic activity. Each of these peptides had a different degree of melanocyte stimulating hormone (MSH) activity as revealed by the Anolis skin bioassay. Three of these TCA-precipitable peptides comigrated with ACTH, beta-lipotrophin, and alpha-MSH on acid-urea gels. Evidence suggesting a precursor-product mode of biosynthesis of the melanotropic peptides is presented. 7 of the 10 TCA-precipitable peptides and the one TCA-soluble peptide with melanotropic activity were released into the medium. The half-time of release of the TCA-precipitable peptides was about 2 h, whereas the half-time of TCA-soluble peptide release was about 30 min. The release of these peptides was inhibited by 5 X 10(-5) M dopamine. Dopamine inhibition of release did not appear to affect the biosynthesis of the melanotropic peptides, but did appear to enhance the degradation of the newly synthesized TCA-soluble peptide in the tissue. White adaptation of the toads greatly decreased the biosynthesis of all of the TCA-precipitable melanotropic peptides.


Ouabain-insensitive salt and water movements in duck red cells. I. Kinetics of cation transport under hypertonic conditions. Duck red cells in hypertonic media experience rapid osmotic shrinkage followed by gradual reswelling back toward their original volume. This uptake of salt and water is self limiting and demands a specific ionic composition of the external solution. Although ouabain (10(-4)M) alters the pattern of cation accumulation from predominantly potassium to sodium, it does not affect the rate of the reaction, or the total amount of salt or water taken up. To study the response without the complications of active Na-K transport, ouabain was added to most incubations. All water accumulated by the cells can be accounted for by net salt uptake. Specific external cation requirements for reswelling include: sufficient sodium (more than 23 mM), and elevated potassium (more than 7 mM). In the absence of external potassium cells lose potassium without gaining sodium and continue to shrink instead of reswelling. Adding rubidium to the potassium- free solution promotes an even greater loss of cell potassium, yet causes swelling due to a net uptake of sodium and rubidium followed by chloride. The diuretic furosemide (10(-3)M) inhibits net sodium uptake which depends on potassium (or rubidium), as well as inhibits net sodium uptake which depends on sodium. As a result, cell volume is stabilized in the presence of this drug by inhibition of shrinkage, at low, and of swelling at high external potassium. The response has a high apparent energy of activation (15-20 kcal/mol). We propose that net salt and water movements in hypertonic solutions containing ouabain are mediated by direct coupling or cis-interaction, between sodium and potassium so that the uphill movement of one is driven by the downhill movement of the other in the same direction.


Ouabain-insensitive salt and water movements in duck red cells. II. Norepinephrine stimulation of sodium plus potassium cotransport. Catecholamines induce net salt and water movements in duck red cells incubated in isotonic solutions. The rate of this response is approximately three times greater than a comparable effect observed in 400 mosmol hypertonic solutions in the absence of hormone (W.F. Schmidt and T. J. McManus. 1977 a.J. Gen. Physiol. 70:59-79. Otherwise, these two systems share a great many similarities. In both cases, net water and salt movements have a marked dependence on external cation concentrations, are sensitive to furosemide and insensitive to ouabain, and allow the substitution of rubidium for external potassium. In the presence of ouabain, but the absence of external potassium (or rubidium), a furosemide-sensitive net extrusion of sodium against a large electrochemical gradient can be demonstrated. When norepinephrine-treated cells are incubated with ouabain and sufficient external sodium, the furosemide-sensitive, unidirectional influxes of both sodium and rubidium are half- maximally saturated at similar rubidium concentrations; with saturating external rubidium, the same fluxes are half-maximal at comparable levels of external sodium. In the absence of sodium, a catecholamine-stimulated, furosemide-sensitive influx of rubidium persists. In the absence of rubidium, a similar but smaller component of sodium influx can be seen. We interpret these results in terms of a cotransport model for sodium plus potassium which is activated by hypertonicity or norepinephrine. When either ion is absent from the incubation medium, the system promotes an exchange-diffusion type of movement of the co-ion into the cells. In the absence of external potassium, net movement of potassium out of the cell leads to a coupled extrusion of sodium against its electrochemical gradient.