Evidence of reduced poly-B-hydroxybutyrate biosynthesis in free-living nitrogen-fixing bacteria, Azotobacter chroococcum, following acquired resistance to the fungicide captan. Some biological activities of Azotobacter chroococcum, strain Azcap 1, (spontaneous mutant, captan resistant up to 300 micrograms/ml) were assayed on RM medium with and without the presence of the fungicide. Comparisons were also carried out with Az. chroococcum sensitive strains Azwt, Azcan 10 and 14. The hydrolysis of captan, incorporated in agar plates of RM at 100 micrograms/ml, was rapid, since on 4-day plates, no effect was found on the strain Azwt, while on freshly prepared ones its growth was completely blocked. As for Azcap 1, grown on RM only, the behaviour was similar to that of sensitive strains, whereas when grown on captan the results of experiments showed: (i) a lag of approximately 12 h to reach the maximum nitrogen-fixing activity; (ii) delay of 12-24 h in the full consumption of glucose present in the medium, although the invertase activity did not present differences; (iii) high ATP culture content during the 50 h of the experiment; (iv) approximately 6-10-fold lower production of PHB (poly-B-hydroxybutyrate); (v) lack of typical encystment phase, for the tested 96 h and reduced viability in developing colonies on agar RM medium. In contrast, when captan was added to cultural medium at sublethal concentration, 50 micrograms/ml for sensitive strain Azwt and 200 micrograms/ml for Azcap 1, the amount of glutathione produced (to remove the fungicide toxicity) was several times higher for the former.


High-performance liquid chromatographic determination of the herbicide imazapyr residues in water and soil. A rapid method for determining residues of the herbicide imazapyr in water and soil is described. The soil samples were extracted with aqueous methanol and, after concentrating, the residue was estimated by HPLC with UV detection at 250 nm. Imazapyr dissolved in water was quantified by injecting the samples without any previous treatments. Analyses were performed without clean-up of soil and water samples. The pre-concentration of samples was required only at very low herbicide amounts. The maximum recovery was achieved by methanol/water (3:2 v/v) with both soils after three extraction procedures. The detection limits were 0.01 mg/l and 0.05 mg/kg in water and soil, respectively.


Mobility of dichlorprop in the soil-water system as a function of different environmental factors. I. A batch experiment. Batch experiments were conducted to study the mobility of 14C-labelled dichlorprop in different soil types. Soils rich in organic carbon showed high sorption capacity compared to sand soil with low content of organic C. Soil to soil variations decreased when corrected for different content of organic C (Kd normalized to Koc). Data obtained in batch experiments fit into linear as well as Freundlich sorption isotherms (17 degrees C). Desorption of [14C]dichlorprop in the soil-water system increased with pH. A significant amount of dichlorprop may be considered as 'non-available' in soils with high organic C, even at relatively high pH-values. The octanol/water partitioning coefficient (Kow) for dichlorprop was inversely related to pH. In the pH range 4-7, the Kow-value varied from 114 to 0.6. The relationship between Koc and pH was similar to the relationship between Kow and pH and the data fitted the following equation: log Koc = 0.5 log Kow + 0.2 (r2 = 0.986).


Mobility of dichlorprop in the soil-water system as a function of different environmental factors. II. A lysimeter experiment. Lysimeter experiments were conducted to study the leaching of [14C]dichlorprop and [3H]water through different soil columns. Results from soil columns collected at Haslemoen showed that an upper silt loam layer (0-18 cm) had higher retention capacity than the underlying sandy loam (35-60 cm) and fine sand (70-95 cm) layers. Leaching through silt clay loam (0-18 cm) columns from Ullensaker was very fast. When the columns received an amount of water corresponding to approximately 10 mm precipitation, up to 50% of the added [14C]dichlorprop leached through the columns. This is probably due to rapid downward movements through macropores (e.g. cracks).


Analytical methodology for screening organophosphorus pesticides in biota samples. The use of gel permeation chromatography (GPC) and capillary gas chromatography (GC) with thermionic detection (NPD) is described as a routine methodology for the determination of organophosphorus pesticides in biota samples. Confirmatory analysis is done by capillary GC with mass spectrometry in the negative chemical ionization mode (NCI-MS). As an example, the use of GPC is described as trace-enrichment technique and clean-up to remove coextractive lipids in samples of mosquito fish Gambussia affinis collected during periods of 1987-1989 in the rice crop fields of the Ebro Delta (Spain). Recoveries of dioxathion, fenitrothion, malathion, tetrachlorvinphos, azinphos-ethyl, ronnel and coumaphos varied between 60% and 80% depending on the compound.


Assessment of the movement of triazole fungicides by soil thin-layer chromatography. Soil TLC was used to assess and compare the mobility of 17 triazole fungicides in soil. A sample of Versailles soil (a silt loam with 2% organic matter) was passed through a 100-microns-meshed screen, and glass plates were coated with this fine fraction at a thickness of 250 microns or 500 microns. The non-labelled compounds were bioassayed to visualize their movement. Penicillium expansum was used as visualizing agent by spraying plates with an agar suspension of the fungus. Plates were then incubated at 28 degrees C, 100% RH. Inhibition areas usually appeared within 36 h. When [14C]triazoles were available, a linear detector and autoradiography were used to visualize the movement and measure the Rf. The Rf values obtained indicate that most of the fungicides were slightly mobile in the Versailles soil. Mobility of these fungicides was inversely related to their octanol/water partition coefficient. Successive leaching were also carried out with radiolabelled compounds, and movement was measured with the linear detector and compared with the position predicted from the initial value of Rf. The advantages and drawbacks of this technique are discussed.


Criteria for evaluating the impact of pesticides on groundwater quality. A lot of data and information are available regarding the presence of pesticides in ground-waters or their tendency to contaminate them. Despite this, for a very large number of pesticides these data and information are almost completely lacking. Many theoretical methods have been proposed to predict the leaching potential of pesticides. Persistence (expressed by DT50) and mobility (expressed by Koc) are key parameters that seem to be particularly representative of the overall leaching potential of nonionic compounds and they are widely used in these methods. Nevertheless, these parameters may vary greatly causing sharp differences in ranking the leaching potential of pesticides. Indeed, when the GUS Index is calculated using the available published values of Koc and DT50 in combinations representing the minimum, medium and maximum leaching potential of herbicides, very different results can be obtained. Many of these compounds can be classified as contaminants or non contaminants, depending on the type of combination used.


Mathematical descriptions of accelerated transformation of 1,3-dichloropropene in soil; a microbiological assessment. The rate of transformation of the soil fumigant (Z)-and (E)-1,3-dichloropropene in moist soil layers was measured at incubation temperatures of 5 degrees C, 10 degrees C and 20 degrees C. 'DD95' was added to four characterized soil layers, in amounts corresponding to realistic field contents after fumigation. Rapid transformation immediately after application was observed in layers with low initial contents (30-300 micrograms/kg dm) and could well be described with a first-order rate model. Incubation at higher doses (5-15 mg/kg dm respectively) showed distinctly different transformation pathways. Degradation curves could well be computed using a microbiological interspective competition (MIC) model for moist soil. The transformation rate is inversely correlated to microorganism population size and growth. Transformation curves described by MIC are characterized by a lag-time, a period of accelerated transformation and a period of decreasing transformation rates. At low temperatures, DT50 values of more than 20 days could be observed. First-order rate computations did not exceed 8 days. The use of different mathematical discriptions for various soil layers and soil temperatures permits simulation of DD95-transformation by microorganisms in the soil profile throughout the growing season.


Binding mechanisms of pesticides to soil humic substances. This review-paper summarizes and discusses the nature of the binding forces involved and the types of mechanisms operating, often simultaneously, in the adsorption processes of several pesticides onto soil humic substances, humic acids and fulvic acids. These include ionic, hydrogen and covalent bonding, charge-transfer or electron donor-acceptor mechanisms, Van der Waals forces, ligand exchange, and hydrophobic bonding or partitioning. Experimental evidence obtained and interpretation provided for the various adsorption processes proposed are briefly presented and commented. The review ends with some concluding remarks and recommendations for future work needed to be done.


Determination of trace element speciation and the role of speciation in aquatic toxicity. Knowledge of trace element speciation in waters is essential to an understanding of aquatic toxicity and bioaccumulation, as well as to the partitioning of elements between water and colloidal and particulate phases. In natural waters, only very small percentages of the dissolved heavy metals, such as copper, lead cadmium or zinc, are present as free (aquo) metal ion; most of the metal is adsorbed to colloidal particles or combined in complexes. For aquatic toxicity studies, the aim of the speciation measurement is to determine the fraction of total dissolved metal (the 'toxic fraction') that will react with, and be transported across, a biological membrane such as a fish gill. In this review, a range of trace element speciation techniques is discussed and compared. A simple anodic stripping voltammetric method is recommended for the measurement of the fraction of electroactive metal in a sample, i.e. the fraction of total dissolved metal that can be deposited into a mercury electrode at the natural pH of the sample. The electroactive fraction is believed to approximate the toxic fraction. A rapid ion exchange method, suitable for field use, is proposed for the determination of the toxic fraction of copper in waters.


Comparison of wet digestion procedures for the determination of cadmium and lead in marine biological tissues by Zeeman graphite furnace atomic absorption spectrophotometry. Three wet digestion procedures, namely, nitric acid/sulphuric acid, nitric acid/hydrogen peroxide and nitric acid/perchloric acid were compared for their relative efficiency in determining cadmium and lead in marine biological tissues. The nitric acid/perchloric acid procedure was the most efficient, whereas the nitric acid/hydrogen peroxide procedure was the least efficient. The nitric acid/sulphuric acid procedure was also found to be effective but there was a problem with the method as the presence of sulphuric acid in the matrix markedly suppressed the absorbance signals especially for lead analysis and thus reduced sensitivity. The addition of ascorbic acid as matrix modifier improved sensitivity. However, this analysis still required the standard addition method. No apparent interferences were encountered for cadmium analysis.


The use of an oxygen bomb as an alternative method for digestion of fish tissue for total mercury analysis. One of the major time consuming steps in many of the methods used for the analysis of fish tissue for total mercury is the wet oxidation by concentrated acids. This paper compares the use of an oxygen bomb with the nitric/sulfuric acid wet oxidation technique for the determination of total mercury in fish tissue. No significant differences existed in the concentrations obtained by wet oxidation and bomb oxidation with absorption by deionised distilled water. When only a small number of samples (< 5) is to be analysed the oxidation bomb is quicker than published techniques. The oxygen bomb technique lacks the hazardous problems associated with the use of concentrated acids and produces a digest suitable for the determination of other elements but has a requirement for added capital cost.


The social epidemiology of disease with particular emphasis on multiple sclerosis. A particular conceptual perspective in the epidemiology of disease is discussed and evaluated: (1) that epidemiologic research is concerned with investigating the possible role played by biological and environmental factors in the etiology of disease but that the particular approach of the social epidemiologist is to concentrate on sociodemographic factors in the explanation; and (2) that a rich tradition of conceptual linkage already exists in epidemiologic research whereby sociologists working separately or in concert with epidemiologists, or physician epidemiologists concerned with details of social behavior and group relationships, have collected an analyzed sociodemographic data on the etiology of all kinds of disease conditions, inclusive of multiple sclerosis (MS). This paper is divided into four subsections which give an indication of its focus: (1) epidemiology and social epidemiologic research; (2) sociodemographic factors in epidemiologic research; (3) contribution of sociology to the social epidemiology of disease; and (4) sociodemographic factors in epidemiologic research on MS. This latter subsection includes a review and critique of some of the most frequently investigated sociodemographic factors in MS research: age, sex, race and socioeconomic status. Although the etiology of MS remains a mystery, sufficient epidemiologic evidence exists to connect three of these four sociodemographic factors to the etiology and distribution of this disease.


Polycyclic aromatic hydrocarbons in air samples of meat smokehouses. In a screening programme nine Danish meat smokehouses were randomly selected for measurements on concentration of airborne polycyclic aromatic hydrocarbons (PAH). A total of 23 stationary air samples were collected during the entire working period of the kiln either above the kiln doors or approximately 2 m in front of the kiln doors (i.e. total exposure on the day of sampling). Three of these samples had a PAH content below the detection limit of the highly sensitive assay employed. Furthermore, eight personal air samples were collected during the periods of tending the kiln (i.e. peak exposure measurement). Three of these samples were below the detection limit. Total airborne PAH concentration of the stationary air samples calculated as the sum of the concentration of 16 selected PAH compounds, was in general far lower than the total airborne PAH concentration measured in the same manner in smokehouses curing fish (Nordholm et al., 1986). In contrast to the study on PAH exposure in smokehouses curing fish, the present study revealed no significant difference between total PAH content in air samples collected above the kilns compared with samples collected approximately 2 m in front of the kiln doors. Calculation of the relative content of the individual PAH compounds in the stationary air samples collected in meat smokehouses showed naphthalene to be the major compound in (70% +/- 26% of total PAH), whereas the relative content of carcinogenic PAH compounds in average represented 4.0% of the total PAH content. However, only approximately 15% of the stationary air samples with detectable content of total PAH contained detectable amounts of carcinogenic PAH compounds. Hence it was concluded that PAH exposure during cold meat curing might be considered a limited health hazard compared with PAH exposure during hot fish curing.


Concentrations of copper, zinc and lead in the Sydney rock oyster, Saccostrea commercialis (Iredale and Roughley) from the Georges River, New South Wales. Copper, zinc and lead were analysed from samples of non-commercially grown Sydney rock oysters collected from the Georges River estuary in spring 1987. The results, when compared with previous data from 1975, indicated a marked increase in the concentration of copper (up to 40%) and zinc (up to 300%). For several sites, the recommended (National Health and Medical Research Council) levels for copper and zinc (70 micrograms g-1 and 1000 micrograms g-1 respectively) were exceeded. There appears to be a decrease in the concentration of lead since 1975. The gradient of increasing copper and zinc concentrations with increasing distance upstream from the mouth of the estuary reported in 1975 could not be statistically validated. A significant correlation was found between copper and zinc loadings in the oysters. It was noted that data collected in 1975 were based on commercially grown oysters. The use of commercially grown oysters, rather than indigenous oysters, to examine interaction of contaminant load and distance upstream, is complicated as commercial oysters are moved within the estuary and between estuaries to maximise growth potential.


Fish as a source of exposure to mercury and selenium. In a total of 395 subjects with varying fish consumption habits, mercury levels in whole blood (B-Hg), and selenium levels in plasma (P-Se) were studied. Also, in subcohorts, mercury levels in blood cells (Ery-Hg; n = 79), plasma (P-Hg; n = 158) and urine (U-Hg; n = 125) were analysed. There were statistically significant associations between fish intake on the one hand, and B-Hg, Ery-Hg and P-Hg, on the other, but not so with U-Hg. In subjects who never had fish, the average B-Hg was 1.8 ng/g, in subjects who had at least two fish meals each week, 6.7 ng/g. Ery-Hg, and to a less extent P-Hg, were associated with levels of marine n-3 polyunsaturated fatty acids (PUFA) in serum phosphatidylcholine. P-Hg and U-Hg were associated with numbers of teeth with amalgam fillings. P-Se also correlated with fish intake. In subjects who never had fish, P-Se averaged 80 micrograms/l, in subjects who had at least two fish meals per week, 91 micrograms/l. There was an association between PUFA and P-Se. Further, there were statistically significant associations between P-Se on the one hand, and B-Hg, Ery-Hg and P-Hg on the other. The data clearly demonstrate the importance of fish for the exposure to methylmercury and selenium in the Swedish diet, and the impact of amalgam as a source of exposure to inorganic mercury.


A source inventory and budget for chlorinated dioxins and furans in the United Kingdom environment. Polychlorinated dibenzo-p-dioxins (PCDDs) and -furans (PCDFs) are ubiquitous in the environment. This paper estimates the present UK environmental loading of PCDD/Fs in soils, vegetation, air, water and sediments. Greater than 95% of the estimated total PCDD/F loading of 5.7 t in the UK environment is present in surface soils. Annual emissions from known primary sources of PCDDs and PCDFs are estimated. The most important of these include: municipal waste incinerator stack emissions (10.9 kg sigma PCDD/F per annum); industrial (7.7 kg/year) and domestic (5.1 kg/year) combustion of coal; clinical waste incinerators (1.7 kg/year); volatilisation from chlorophenol-treated substrates (1.7 kg/year) and combustion of leaded petrol by motor vehicles (0.7 kg/year). These sources are generally easy to define and reasonably reliable national estimates can be obtained. More difficult to quantify are secondary releases from the large UK stock of pentachlorophenol (PCP) and PCP-treated products, which may represent quantitatively one of the most important sources of total PCDD/Fs to the environment. Estimates of homologue-specific emissions indicate that combustion processes represent a far more significant source of tetra and penta CDD/Fs than do chlorophenols, which in turn constitute a greater source of hepta- and octachlorinated congeners. Direct emission of PCDD/Fs into the atmosphere from combustion processes facilitates their atmospheric transport to remote locations. This, coupled with the diffuse nature of combustion processes, means that the effects of PCDD/F contamination originating from anthropogenic combustion are more widespread than those from the use and disposal of chlorophenols. Contamination from chlorophenols will be more localised, owing to the insignificance of direct atmospheric release pathways for this source. Although there is reasonable agreement between the estimated current annual flux and the present UK environmental loading of PCDDs and PCDFs, a large discrepancy exists between the sum of the annual contributions from primary sources and this annual flux. Whilst the existence of an as yet unidentified source or sources or gross underestimates of known sources cannot be excluded, it is proposed that much of this discrepancy may be accounted for by secondary releases from the use and disposal of chlorophenols and the long-range transport, continued remobilisation and subsequent redeposition of PCDDs and PCDFs already present in the environment. Despite limited evidence for a modest decline in levels of PCDDs and PCDFs in some environmental compartments over the last 20 years, the environmental persistence of these chemicals means that they will remain in the UK environment for the foreseeable future despite recent action to curb primary emissions.


Atmospheric deposition of trace elements around point sources and human health risk assessment. I: Impact zones near a source of lead emissions. The deposition of lead was monitored over 8 years in the area around a car battery factory north of Copenhagen, Denmark. The area also has heavy traffic. Deposition was measured by in-situ grown vegetables, transplant grass culture biomonitors, bulk deposition and soil samples. Three impact zones were identified by a multivariate statistical analysis. Within each zone, the total dietary intake of lead was estimated for adults and children as a percentage of the provisional tolerably weekly intake (PTWI), and as a result recommendation on restrictions in use of locally grown fruit and vegetables were given to the public. The pattern of lead deposition in the area during the period 1981-1988 was monitored and the amount of lead ingested via vegetables was toxically evaluated. Lead emission reduction measures introduced in the factory and in the traffic during the period produced significant reductions in lead deposition.


Atmospheric deposition of trace elements around point sources and human health risk assessment. II. Uptake of arsenic and chromium by vegetables grown near a wood preservation factory. Kale, lettuce, carrots and potatoes were grown in 20 experimental plots surrounding a wood preservation factory, to investigate the amount and pathways for plant uptake of arsenic and chromium. Arsenate used in the wood preservation process is converted to the more toxic arsenite by incineration of waste wood and is emitted into the atmosphere. Elevated concentrations of inorganic arsenic and chromium were found both in the test plants and in the soil around the factory. Multivariate statistical analysis of the results indicated that the dominating pathway of arsenic and chromium from the factory to the leafy vegetables grown nearby was by direct atmospheric deposition, while arsenic in the root crops originated from both the soil and the atmosphere. Consumption of vegetables grown near the source would result in an increased intake of inorganic arsenic, but the intake via the total diet was estimated to be below the provisional tolerable daily intake for inorganic arsenic established by FAO/WHO.


Genome analysis and the human X chromosome. A unified genetic, physical, and functional map of the human X chromosome is being built through a concerted, international effort. About 40 percent of the 160 million base pairs of the X chromosome DNA have been cloned in overlapping, ordered contigs derived from yeast artificial chromosomes. This rapid progress toward a physical map is accelerating the identification of inherited disease genes, 26 of which are already cloned and more than 50 others regionally localized by linkage analysis. This article summarizes the mapping strategies now used and the impact of genome research on the understanding of X chromosome inactivation and X-linked diseases.


Immuno-PCR: very sensitive antigen detection by means of specific antibody-DNA conjugates. An antigen detection system, termed immuno-polymerase chain reaction (immuno-PCR), was developed in which a specific DNA molecule is used as the marker. A streptavidin-protein A chimera that possesses tight and specific binding affinity both for biotin and immunoglobulin G was used to attach a biotinylated DNA specifically to antigen-monoclonal antibody complexes that had been immobilized on microtiter plate wells. Then, a segment of the attached DNA was amplified by PCR. Analysis of the PCR products by agarose gel electrophoresis after staining with ethidium bromide allowed as few as 580 antigen molecules (9.6 x 10(-22) moles) to be readily and reproducibly detected. Direct comparison with enzyme-linked immunosorbent assay with the use of a chimera-alkaline phosphatase conjugate demonstrates that enhancement (approximately x 10(5)) in detection sensitivity was obtained with the use of immuno-PCR. Given the enormous amplification capability and specificity of PCR, this immuno-PCR technology has a sensitivity greater than any existing antigen detection system and, in principle, could be applied to the detection of single antigen molecules.


The B cell antigen receptor complex: association of Ig-alpha and Ig-beta with distinct cytoplasmic effectors. The B cell antigen receptor complex is a hetero-oligomeric structure composed of antigen binding, membrane immunoglobulin, and transducer-transporter substructures. The transducer-transporter substructure is composed of disulfide-linked dimers of immunoglobulin (Ig)-alpha and Ig-beta/gamma subunits that are products of the mb-1(alpha) and B29 (beta/gamma) genes. Although the receptor complex associates with Src family kinases that are activated after receptor ligation, the site of interaction of these and other cytoplasmic effector molecules with receptor subunits is unknown. The cytoplasmic tails of Ig-alpha and Ig-beta chains were found to associate with distinct sets of effector molecules. The Ig-alpha chain cytoplasmic domain bound to the Src family kinases Lyn and Fyn, phosphatidylinositol-3 kinase (PI-3 kinase), and an unidentified 38-kilodalton phosphoprotein; the cytoplasmic tail of Ig-beta bound PI-3 kinase and unidentified 40- and 42-kilodalton phosphoproteins. Binding activity was found to occur within a 26-amino acid sequence of Ig-alpha and Ig-beta that contains a motif [(Asp or Glu)-(any amino acid)7-(Asp or Glu)-Tyr-(any amino acid)3-Leu-(any amino acid)7-Tyr-(any amino acid)2-(Leu or Ile)] previously implicated in signal transduction via other receptors including the Fc epsilon receptor I and the T cell antigen receptor. These findings indicate that the subunits act independently to activate distinct second messenger pathways.


Production of the Alzheimer amyloid beta protein by normal proteolytic processing. The 4-kilodalton (39 to 43 amino acids) amyloid beta protein (beta AP), which is deposited as amyloid in the brains of patients with Alzheimer's diseases, is derived from a large protein, the amyloid beta protein precursor (beta APP). Human mononuclear leukemic (K562) cells expressing a beta AP-bearing, carboxyl-terminal beta APP derivative released significant amounts of a soluble 4-kilodalton beta APP derivative essentially identical to the beta AP deposited in Alzheimer's disease. Human neuroblastoma (M17) cells transfected with constructs expressing full-length beta APP and M17 cells expressing only endogenous beta APP also released soluble 4-kilodalton beta AP, and a similar, if not identical, fragment was readily detected in cerebrospinal fluid from individuals with Alzheimer's disease and normal individuals. Thus cells normally produce and release soluble 4-kilodalton beta AP that is essentially identical to the 4-kilodalton beta AP deposited as insoluble amyloid fibrils in Alzheimer's disease.


Structural basis of the intrasteric regulation of myosin light chain kinases. The smooth muscle myosin light chain kinase (smMLCK) catalytic core was modeled by using the crystallographic coordinates of the cyclic AMP-dependent protein kinase catalytic subunit (cAPK) and a bound pseudosubstrate inhibitor peptide, PKI(5-24). Despite only 30% identity in amino acid sequence, the MLCK sequence can be readily accommodated in this structure. With the exception of the short B-helix, all major elements of secondary structure in the core are very likely conserved. The active site of the modeled MLCK complements the known requirements for peptide substrate recognition. MLCK contains a pseudosubstrate sequence that overlaps the calmodulin binding domain and has been proposed to act as an intrasteric inhibitor and occupy the substrate binding site in the absence of Ca(2+)-calmodulin. The pseudosubstrate sequence can be modeled easily into the entire backbone of PKI(5-24). The results demonstrate that the intrasteric model for regulation of MLCK by intramolecular competitive inhibition is structurally plausible.


The human Y chromosome: a 43-interval map based on naturally occurring deletions. A deletion map of the human Y chromosome was constructed by testing 96 individuals with partial Y chromosomes for the presence or absence of many DNA loci. The individuals studied included XX males, XY females, and persons in whom chromosome banding had revealed translocated, deleted, isodicentric, or ring Y chromosomes. Most of the 132 Y chromosomal loci mapped were sequence-tagged sites, detected by means of the polymerase chain reaction. These studies resolved the euchromatic region (short arm, centromere, and proximal long arm) of the Y chromosome into 43 ordered intervals, all defined by naturally occurring chromosomal breakpoints and averaging less than 800 kilobases in length. This deletion map should be useful in identifying Y chromosomal genes, in exploring the origin of chromosomal disorders, and in tracing the evolution of the Y chromosome.


A comprehensive genetic linkage map of the human genome. NIH/CEPH Collaborative Mapping Group. A genetic linkage map of the human genome was constructed that consists of 1416 loci, including 279 genes and expressed sequences. The loci are represented by 1676 polymorphic systems genotyped with the CEPH reference pedigree resource. A total of 339 microsatellite repeat markers assayed by PCR are contained within the map, and of the 351 markers with heterozygosities of at least 70%, 205 are microsatellites. Seven telomere loci define physical and genetic endpoints for 2q, 4p, 7q, 8p, 14q, 16p, and 16q, and in other cases distal markers on the maps have been localized to terminal cytogenetic bands. Therefore, at least 92% of the autosomal length of the genome and 95% of the X chromosome is estimated to be spanned by the map. Since the maps have relatively high marker density and numerous highly informative loci, they can be used to map disease phenotypes, even for those with limited pedigree resources. The baseline map provides a foundation for achieving continuity of clone-based physical maps and for the development of a truly integrated physical, genetic, and cytogenetic map of the human.


What if Minkowski had been ageusic? An alternative angle on diabetes. Despite decades of intensive investigation, the basic pathophysiological mechanisms responsible for the metabolic derangements associated with diabetes mellitus have remained elusive. Explored here is the possibility that traditional concepts in this area might have carried the wrong emphasis. It is suggested that the phenomena of insulin resistance and hyperglycemia might be more readily understood if viewed in the context of underlying abnormalities of lipid metabolism.


Resonance-enhanced x-rays in thin films: a structure probe for membranes and surface layers. An x-ray resonance effect in an organic thin film on an x-ray reflecting mirror is reported. The resonance effect is the result of interference between reflected and refracted x-rays at the air-organic thin film interface and occurs at incident angles slightly above the critical angle of the film. In excellent agreement with theory, the primary resonant x-ray electric field that is confined in the organic thin film is approximately 20 times as intense as the electric field of the incident beam when measured at a position close to the center of the film. Resonance-enhanced x-rays can be used to characterize the internal structure of Langmuir-Blodgett thin film membranes. This effect may also find use in x-ray-based thin film devices and in the structural analysis of adlayers and surfaces that have thus far proved difficult, if not impossible, to study because of sensitivity limitations.


Submicrometer intracellular chemical optical fiber sensors. A thousandfold miniaturization of immobilized optical fiber sensors, a millionfold or more sample reduction, and at least a hundredfold shorter response time, all simultaneously, were achieved by combining nanofabricated optical fiber tips with near-field photopolymerization. Specifically, pH optical fiber sensors were prepared with internal calibration, making use of the differences in both fluorescence and absorption of the acidic and basic dye species. The submicrometer sensors have excellent detection limits, as well as photostability, reversibility, and millisecond response times. Successful applications include intracellular and intraembryonic measurements. Potential applications include spatially and temporally resolved chemical analysis and kinetics inside single biological cells and their substructures.


Homobatrachotoxin in the genus Pitohui: chemical defense in birds? Three passerine species in the genus Pitohui, endemic to the New Guinea subregion, contain the steroidal alkaloid homobatrachotoxin, apparently as a chemical defense. Toxin concentrations varied among species but were always highest in the skin and feathers. Homobatrachotoxin is a member of a class of compounds collectively called batrachotoxins that were previously considered to be restricted to neotropical poison-dart frogs of the genus Phyllobates. The occurrence of homobatrachotoxin in pitohuis suggests that birds and frogs independently evolved this class of alkaloids.


Saltation and stasis: a model of human growth. Human growth has been viewed as a continuous process characterized by changing velocity with age. Serial length measurements of normal infants were assessed weekly (n = 10), semiweekly (n = 18), and daily (n = 3) (19 females and 12 males) during their first 21 months. Data show that growth in length occurs by discontinuous, aperiodic saltatory spurts. These bursts were 0.5 to 2.5 centimeters in amplitude during intervals separated by no measurable growth (2 to 63 days duration). These data suggest that 90 to 95 percent of normal development during infancy is growth-free and length accretion is a distinctly saltatory process of incremental bursts punctuating background stasis.


Antibody-catalyzed rearrangement of the peptide bond. The generation of antibodies from a bifunctional cyclic phosphinate transition-state analog provided agents capable of efficiently catalyzing both steps of the overall conversion of a substrate containing an asparaginyl-glycyl sequence through a succinimide intermediate to the products aspartyl-glycyl and the rearranged isoaspartyl-glycyl sequence. This reaction provides a potential means in addition to amide cleavage for the deactivation of protein or peptide biological functions in vivo.


Fatal familial insomnia and familial Creutzfeldt-Jakob disease: disease phenotype determined by a DNA polymorphism. Fatal familial insomnia (FFI) and a subtype of familial Creutzfeldt-Jakob disease (CJD), two clinically and pathologically distinct diseases, are linked to the same mutation at codon 178 (Asn178) of the prion protein gene. The possibility that a second genetic component modified the phenotypic expression of the Asn178 mutation was investigated. FFI and the familial CJD subtype segregated with different genotypes determined by the Asn178 mutation and the methionine-valine polymorphism at codon 129. The Met129, Asn178 allele segregated with FFI in all 15 affected members of five kindreds whereas the Val129, Asn178 allele segregated with the familial CJD subtype in all 15 affected members of six kindreds. Thus, two distinct disease phenotypes linked to a single pathogenic mutation can be determined by a common polymorphism.


Ikaros, an early lymphoid-specific transcription factor and a putative mediator for T cell commitment. In a screen for transcriptional regulators that control differentiation into the T cell lineage, a complementary DNA was isolated encoding a zinc finger protein (Ikaros) related to the Drosophila gap protein Hunchback. The Ikaros protein binds to and activates the enhancer of a gene encoding an early T cell differentiation antigen, CD3 delta. During development, Ikaros messenger RNA was first detected in the mouse fetal liver and the embryonic thymus when hematopoietic and lymphoid progenitors initially colonize these organs; no expression was observed in the spleen or the bone marrow. The pattern of Ikaros gene expression and its ability to stimulate CD3 delta transcription support the model that Ikaros functions in the specification and maturation of the T lymphocyte.


A GDP dissociation inhibitor that serves as a GTPase inhibitor for the Ras-like protein CDC42Hs. Members of the family of Ras-related guanosine triphosphate (GTP) binding proteins appear to take part in the regulation of a number of biological processes, including cell growth and differentiation. Three different classes of proteins that regulate the GTP binding and GTP hydrolytic activities of the Ras family members have been identified. These different regulatory proteins inhibit guanosine diphosphate (GDP) dissociation (designated as GDIs), stimulate GDP dissociation and GDP-GTP exchange (designated as GDSs), or stimulate GTP hydrolysis (designated as GAPs). In the case of the Ras-like protein CDC42Hs, which is the human homolog of a Saccharomyces cerevisiae cell division cycle protein, the GDI protein also inhibited both the intrinsic and GAP-stimulated hydrolysis of GTP. These findings establish an additional role for the GDI protein--namely, as a guanosine triphosphatase (GTPase) inhibitory protein for a Ras-like GTP binding protein.


Selecting T cell receptors with high affinity for self-MHC by decreasing the contribution of CD8. Selective events during T cell repertoire development in the thymus include both the positive selection of cells whose receptors recognize self-major histocompatibility complex (MHC) molecules and negative selection (tolerance) of cells whose interaction with self-MHC is of high affinity. The affinity of T cell interactions with class I MHC molecules includes contributions by both the T cell receptor and the CD8 coreceptor. Therefore, by decreasing the affinity of the interaction with CD8, T cells whose receptors have relatively high affinities for self-MHC may survive negative selection. Such T cells were generated and those T cells reactive with self-MHC plus antigen also displayed low affinity for self.


A surface protease and the invasive character of plague. A 9.5-kilobase plasmid of Yersinia pestis, the causative agent of plague, is required for high virulence when mice are inoculated with the bacterium by subcutaneous injection. Inactivation of the plasmid gene pla, which encodes a surface protease, increased the median lethal dose of the bacteria for mice by a millionfold. Moreover, cloned pla was sufficient to restore segregants lacking the entire pla-bearing plasmid to full virulence. Both pla+ strains injected subcutaneously and pla- mutants injected intravenously reached high titers in liver and spleen of infected mice, whereas pla- mutants injected subcutaneously failed to do so even though they establish a sustained local infection at the injection site. More inflammatory cells accumulated in lesions caused by the pla- mutants than in lesions produced by the pla+ parent. The Pla protease was shown to be a plasminogen activator with unusual kinetic properties. It can also cleave complement C3 at a specific site.


Membrane fusion.

Membrane fusion. Common themes are emerging from the study of viral, cell-cell, intracellular, and liposome fusion. Viral and cellular membrane fusion events are mediated by fusion proteins or fusion machines. Viral fusion proteins share important characteristics, notably a fusion peptide within a transmembrane-anchored polypeptide chain. At least one protein involved in a cell-cell fusion reaction resembles viral fusion proteins. Components of intracellular fusion machines are utilized in multiple membrane trafficking events and are conserved through evolution. Fusion pores develop during and intracellular fusion events suggesting similar mechanisms for many, if not all, fusion events.


The annexins and exocytosis.

The annexins and exocytosis. The annexins are a group of homologous proteins that bind phospholipids in the presence of calcium. They may provide a major pathway for communication between cellular membranes and their cytoplasmic environment. Annexins have a characteristic "bivalent" activity in the sense that they can draw two membranes together when activated by calcium. This has led to the hypothesis that certain members of this protein family may initiate contact and fusion between a secretory vesicle membrane and the plasma membrane during the process of exocytosis.


The nuclear membrane.

The nuclear membrane. The nuclear membrane forms a major barrier within the cell, permitting levels of regulation not found in prokaryotes. The dynamics and diverse functions of the nuclear membrane and its associated structures are considered in this review. The role of the nuclear pore complex in selective transport across the nuclear membrane has been studied to a considerable degree; however, many crucial questions remain. Components of a signal transduction mechanism are associated with the nucleus, suggesting that nuclear functions may be influenced directly by this system. The involvement of the heat shock cognate protein Hsc70 in nuclear protein import is discussed, and a specific signal-presentation role for this protein is proposed.


Regulation of cell surface polarity from bacteria to mammals. The generation of unique domains on the cell, cell surface polarity, is critical for differentiation into the diversity of cell structures and functions found in a wide variety of organisms and cells, including the bacterium Caulobacter crescentus, the budding yeast Saccharomyces cerevisiae, and mammalian polarized epithelial cells. Comparison of the mechanisms for establishing polarity in these cells indicates that restricted membrane protein distributions are generated by selective protein targeting to, and selective protein retention at, the cell surface. Initiation of these mechanisms involves reorientation of components of the cytoskeleton and protein transport pathways toward restricted sites at the cell surface and formation of a targeting patch at those sites for selective recruitment and retention of proteins.


Cytoskeleton--plasma membrane interactions. Proteins at the boundary between the cytoskeleton and the plasma membrane control cell shape, delimit specialized membrane domains, and stabilize attachments to other cells and to the substrate. These proteins also regulate cell locomotion and cytoplasmic responses to growth factors and other external stimuli. This diversity of cellular functions is matched by the large number of biochemical mechanisms that mediate the connections between membrane proteins and the underlying cytoskeleton, the so-called membrane skeleton. General organizational themes are beginning to emerge from examination of this biochemical diversity.


Selectins: interpreters of cell-specific carbohydrate information during inflammation. Although a bewildering array of cell surface carbohydrate structures have been described, the physiological relevance of any of these complex molecules has often eluded biologists. A family of cell surface glycoproteins, the "selectins," has a characteristic ability to use some of these carbohydrate structures in adhesive mechanisms that help localize leukocytes to regions of inflammation. This article will review the biology of these carbohydrate-binding adhesive proteins and discuss the potential for developing anti-inflammatory antagonists that could inhibit binding events that are selectin-mediated.


Chemical contrast in X-ray microscopy and spatially resolved XANES spectroscopy of organic specimens. The scanning transmission x-ray microscope at the National Synchrotron Light Source has been used to record x-ray absorption near-edge structure (XANES) spectra from 0.01-square-micrometer regions of organic specimens. The spectral features observed reflect the molecular structure of the dominant absorbing atoms and provide the contrast mechanism for high-resolution imaging with chemical sensitivity. This technique was used with x-ray energies near the carbon K absorption edge to identify and map separate phases in various polymer blends and to map the DNA distribution in chromosomes with a spatial resolution of 55 nanometers.


Absence of microsomal triglyceride transfer protein in individuals with abetalipoproteinemia. Abetalipoproteinemia is a human genetic disease that is characterized by a defect in the assembly or secretion of plasma very low density lipoproteins and chylomicrons. The microsomal triglyceride transfer protein (MTP), which is located in the lumen of microsomes isolated from the liver and intestine, has been proposed to function in lipoprotein assembly. MTP activity and the 88-kilodalton component of MTP were present in intestinal biopsy samples from eight control individuals but were absent in four abetalipoproteinemic subjects. This finding suggests that a defect in MTP is the basis for abetalipoproteinemia and that MTP is indeed required for lipoprotein assembly.


Prevalence of AIDS-related risk factors and condom use in the United States. A national probability survey of human immunodeficiency virus (HIV)-related risk factors among the general heterosexual population, the National AIDS (acquired immunodeficiency syndrome) Behavioral Surveys, has obtained data from 10,630 respondents. Data are presented on the prevalence of HIV-related risks in the general heterosexual population, on the distribution of the three largest risk groups across social strata, and on the prevalence and distribution of condom use among heterosexuals reporting a risk factor. Between 15 and 31 percent of heterosexuals nationally and 20 and 41 percent in cities with a high prevalence of AIDS reported an HIV risk factor. Condom use was relatively low. Only 17 percent of those with multiple sexual partners, 12.6 percent of those with risky sexual partners, and 10.8 percent of untested transfusion recipients used condoms all the time. Overall, the results suggest that current HIV prevention programs have, to a very limited extent, reached those heterosexuals with multiple sexual partners but have failed to reach many other groups of the heterosexual population at risk for HIV. New public health strategies may be needed for these specific risk groups.


Direct mechanical measurements of the elasticity of single DNA molecules by using magnetic beads. Single DNA molecules were chemically attached by one end to a glass surface and by their other end to a magnetic bead. Equilibrium positions of the beads were observed in an optical microscope while the beads were acted on by known magnetic and hydrodynamic forces. Extension versus force curves were obtained for individual DNA molecules at three different salt concentrations with forces between 10(-14) and 10(-11) newtons. Deviations from the force curves predicted by the freely jointed chain model suggest that DNA has significant local curvature in solution. Ethidium bromide and 4',6-diamidino-2-phenylindole had little effect on the elastic response of the molecules, but their extent of intercalation was directly measured. Conversely, the effect of bend-inducing cis-diamminedichloroplatinum (II) was large and supports the hypothesis of natural curvature in DNA.


The evolutionary convergence of hearing in a parasitoid fly and its cricket host. Parasitism is a widespread and diverse life strategy that connects species throughout the animal kingdom. Female parasitoid flies of the genus Ormia must find a specific cricket host on which to deposit their parasitic maggots. To reproduce, female flies must perform the same task as female crickets: find a singing male cricket. These flies have evolved a unique hearing organ that allows them to detect and locate singing male crickets. Through evolutionary convergence, these flies possess a hearing organ that much more resembles a cricket's ear than a typical fly's ear, allowing these parasitoids to take advantage of the sensory ecological niche of their host.


Cooperativity induced by a single mutation at the subunit interface of a dimeric enzyme: glutathione reductase. When glycine418 of Escherichia coli glutathione reductase, which is in a closely packed region of the dimer interface, is replaced with a bulky tryptophan residue, the enzyme becomes highly cooperative (Hill coefficient 1.76) for glutathione binding. The cooperativity is lost when the mutant subunit is hybridized with a wild-type subunit to create a heterodimer. The mutation appears to disrupt atomic packing at the dimer interface, which induces a change of kinetic mechanism. A single mutation in a region of the protein remote from the active site can thus act as a molecular switch to confer cooperativity on an enzyme.


In vitro transcriptional activation by a metabolic intermediate: activation by Leu3 depends on alpha-isopropylmalate. In the absence of the leucine biosynthetic precursor alpha-isopropylmalate (alpha-IPM), the yeast LEU3 protein (Leu3p) binds DNA and acts as a transcriptional repressor in an in vitro extract. Addition of alpha-IPM resulted in a dramatic increase in Leu3p-dependent transcription. The presence of alpha-IPM was also required for Leu3p to compete effectively with another transcriptional activator, GAL4/VP16, for limiting transcription factors. Therefore, the addition of alpha-IPM appears to convert a transcriptional repressor into an activator. This represents an example in eukaryotes of direct transcriptional regulation by a small effector molecule.


Bacteriophage lambda PaPa: not the mother of all lambda phages. The common laboratory strain of bacteriophage lambda--lambda wild type or lambda PaPa--carries a frameshift mutation relative to Ur-lambda, the original isolate. The Ur-lambda virions have thin, jointed tail fibers that are absent from lambda wild type. Two novel proteins of Ur-lambda constitute the fibers: the product of stf, the gene that is disrupted in lambda wild type by the frameshift mutation, and the product of gene tfa, a protein that is implicated in facilitating tail fiber assembly. Relative to lambda wild type, Ur-lambda has expanded receptor specificity and adsorbs to Escherichia coli cells more rapidly.


Assignment of a locus for familial melanoma, MLM, to chromosome 9p13-p22. Linkage analysis of ten Utah kindreds and one Texas kindred with multiple cases of cutaneous malignant melanoma (CMM) provided evidence that a locus for familial melanoma susceptibility is in the chromosomal region 9p13-p22. The genetic markers analyzed reside in a candidate region on chromosome 9p21, previously implicated by the presence of homozygous deletions in melanoma tumors and by the presence of a germline deletion in an individual with eight independent melanomas. Multipoint linkage analysis was performed between the familial melanoma susceptibility locus (MLM) and two short tandem repeat markers, D9S126 and the interferon-alpha (IFNA) gene, which reside in the region of somatic loss in melanoma tumors. An analysis incorporating a partially penetrant dominant melanoma susceptibility locus places MLM near IFNA and D9S126 with a maximum location score of 12.71. Therefore, the region frequently deleted in melanoma tumors on 9p21 presumably contains a locus that plays a critical role in predisposition to familial melanoma.


B cells turn off virgin but not memory T cells. There are three possible outcomes when a T cell recognizes a cell bearing a self or foreign antigen. (i) The T cell is not sufficiently signaled and is unaffected. (ii) The T cell is activated. (iii) The T cell is turned off. The differentiation state of the T cell is critical to the outcome. Although both virgin and memory T cells can be activated by antigens presented by "professional" antigen-presenting cells such as dendritic cells, they differ in their responses to B cells. Experienced T cells respond to antigen presented by B cells, whereas virgin T cells are rendered tolerant. These findings may relate to the phenomena of low- and high-zone tolerance, neonatal tolerance, and the beneficial effect of blood transfusions on allograft survival.


Post-transcriptional regulation of early T cell development by T cell receptor signals. During differentiation in the thymus, immature T cells progress through an ordered sequence of developmental stages that are best characterized by variable expression of the co-receptor molecules CD4 and CD8. Crosslinking of T cell receptor (TCR) molecules on precursor thymocytes was found to block their differentiation into CD4+CD8+ cells by eliminating messenger RNA's encoding two families of developmentally important molecules: the co-receptor molecules CD4 and CD8 and the recombination activating genes 1 and 2. TCR-induced post-transcriptional regulation in early thymocytes was specific for selective messenger RNA's, required protein synthesis, and was itself developmentally regulated. These data identify a post-transcriptional mechanism that is influenced by TCR signals and that regulates early thymocyte development.


Residual vision in a scotoma: implications for blindsight. Blindsight, the ability of some blind patients to describe attributes of stimuli they have no conscious awareness of seeing, has been attributed to a secondary (retinotectal) visual pathway. However, it has also been proposed that blindsight could be due to residual function within the primary (geniculostriate) visual pathway. Data have now been obtained that support the second alternative. With an image stabilizer ensuring the accurate retinal placement of stimuli, dense visual field mapping was carried out with a hemianopic patient. This perimetry revealed, embedded in the patient's scotoma, an isolated 1-degree island of residual vision that was not disclosed by conventional perimetric methods. Stimuli presented to this island could be detected and discriminated, although the subject reported he did not see them. The existence of this island of vision implies a corresponding island of functioning cortex within the patient's lesion. Other instances of blindsight may be mediated by similar islands of functioning cortex.


Posterior tibial tendon dysfunction.

Posterior tibial tendon dysfunction. Posterior tibial tendon dysfunction, a common entity, frequently is unrecognized and inappropriately managed. Acutely, pain and swelling are present over the medial ankle and longitudinal arch. Long-standing inflammation can lead to tendon rupture, resulting in a progressive planovalgus or "flat foot" deformity. Plain radiographs illustrate the changes in bony anatomy associated with chronic posterior tibial deficiency, while magnetic resonance imaging scans can identify the three stages of posterior tibial tendon pathology. Most cases are amenable to conservative therapy, including rest and administration of nonsteroidal antiflammatory agents. Often a short period of immobilization in a cast or the use of an orthosis is beneficial. In cases with persistent tenosynovitis, complete tendon rupture, or progressive deformity, surgical intervention is indicated.


Primary Sjögren's syndrome--clinical and laboratory markers of disease activity. Primary Sjögren's syndrome is a chronic autoimmune disorder of the lacrimal and salivary glands, reflecting general involvement of the exocrine tissues and leading to functional impairment. This polyglandular disease is often associated with systemic extraglandular manifestations, and laboratory tests usually indicate polyclonal B-lymphocyte hyperactivity. Clinical and laboratory markers monitoring the disease processes are needed for improved management of primary Sjögren's syndrome. However, incomplete knowledge of the long-term course of inflammation as well as of clinical manifestations makes precise and simple directions for monitoring disease activity in primary Sjögren's syndrome difficult. This review describes potential primary (eg, salivary gland histopathology, autoantibodies, soluble interleukin-2 receptors, and beta 2-microglobulin) and secondary disease activity markers (clinical and laboratory signs of glandular and extraglandular organ damage) and their known associations. The importance of genetic characteristics, patient age, and symptom duration for the disease activity markers is indicated. The systematic use of primary and secondary disease activity markers will improve our understanding of primary Sjögren's syndrome and help create better guidelines for monitoring the disease.


A clinical, serological, and histopathological study of myositis patients with and without anti-RNP antibodies. Twenty-nine patients with myositis, including 10 with polymyositis (PM), 6 with dermatomyositis (DM), and 13 with myositis associated with a connective tissue disease (CTD), were followed up for a mean observation time of 49 months. The 13 patients with CTD-associated myositis were further separated by the presence or absence of anti-RNP antibodies. The functional disability at diagnosis was pronounced without differences between the groups. The patients with anti-RNP antibodies did not differ from the other patients regarding initial muscle weakness, erythrocyte sedimentation rate, or creatinine phosphokinase values, but the histopathological muscle changes were generally milder. Rapid improvement of muscle strength on moderate doses of corticosteroids was seen in most patients. At the end of study, corticosteroid treatment had been withdrawn from 17 patients because of remission, including 6 of the 7 patients with anti-RNP antibodies. The presence of electromyographic changes compatible with myositis, pronounced muscle weakness before treatment, and a low erythrocyte sedimentation rate seemed to indicate a less favorable outcome unrelated to diagnostic subgroupings. However, the combination was rarely found among the anti-RNP-positive patients.


Amyloidosis.

Amyloidosis. Amyloidosis is a heterogenous group of diseases characterized by deposition of a fibrillar, proteinaceous material, amyloid, in various tissues and organs. Increasing knowledge about the different proteins that constitute the amyloid fibrils has made it possible to classify amyloidosis by the fibril protein, which appears more rational than the traditional classification by its clinical expression. A serum protein is the precursor of the amyloid fibril protein in the various systemic forms of amyloidosis. Although the chemical composition of amyloid is presently well known, the pathogenetic processes that convert such proteins into a fibrillar form and lay them down in the tissues are far from clarified. This review describes the amyloid deposits, some putative pathogenetic mechanisms, and the clinical, therapeutic, and prognostic aspects of the most important forms of amyloid disease.


Timed treatment of the arthritic diseases: a review and hypothesis. Evidence has been accumulating regarding the importance of biological rhythms in the diagnosis and treatment of a variety of diseases and disorders. Increasingly, the arthritides have shown statistically quantifiable rhythmic parameters. Included in the latter group are joint pain and joint size. In addition, a number of drugs used to treat rheumatic diseases have varying therapeutic and toxic effects based on the time of day of administration. Among these drug classes are nonsteroidal antiinflammatory drugs, glucocorticoids, and a number of cytostatic agents. In the last group of agents, experience in treating malignant disease suggests that time-specified treatment may reduce the toxic effects of low-dose cytostatic treatment of rheumatoid arthritis (RA) and related diseases. This article reviews that evidence and suggests a rationale for the timed treatment of RA with methotrexate.


Transient osteoporosis of the hip.

Transient osteoporosis of the hip. Transient osteoporosis of the hip (TOH) is an uncommon but possibly underdiagnosed condition. This pattern of regional osteoporosis affects previously healthy middle-aged men, and women in the third trimester of pregnancy. Its etiology is still unclear, yet in view of similarities to regional migratory osteoporosis and reflex sympathetic dystrophy, vascular and neurologic disturbances have been proposed as the possible pathogenetic mechanisms. Pain in the hip area and functional disability of the affected limb are the main clinical signs. Diagnosis is supported by local radiological osteopenia whose gradual disappearance parallels the spontaneous recovery. Bone scintigraphy, magnetic resonance imaging, computed tomography, and other imaging methods are supplementary diagnostic tools. Exclusion of more common entities is required. The purpose of this report is to elucidate the diagnostic and therapeutic aspects of TOH and to stimulate the physician's awareness of this condition, recognition of which may prevent unnecessary invasive procedures and inadequate treatment.


[Impotence from the 70's through the 90's: 20 years of evolution of diagnosis and therapy]. The surgical treatment of vascular impotence has evolved as our understanding of the haemodynamics of erection advanced. In the early Seventies the direct revascularization techniques which create an anastomosis between an artery and the corpora cavernosa came to be so much in use that an era of so-called "pure arteriogenic impotence" seemed to be dawning. An arterial role in the pathogenesis of importance gained increasing support during that decade, as the use of a number of techniques for the diagnostic assessment of penile haemodynamics becomes widespread (Doppler ultrasound, determination of the penile-brachial index, selective hypogastric arteriography, penile radionuclide scan, penile plethysmography). Corpora cavernosa-direct revascularization techniques, such as the Epigastric-Corporal and Femoro-Corporal trans-Saphena anastomoses, were developed, the latter being proposed by Michal in 1973. By the late Seventies, however, most Authors had abandoned these techniques. Severe haemodynamic side-effects, such as uninterrupted intra-cavernous high pressure and attendant permanent tumescence of penis, were found to induce the microfibrosis of erectile tissues and the thrombosis at the site of the anastomosis. In this period, "venous leakage" became, with the advent of cavernosography, a recognized factor in the pathogenesis of impotence. However, the concept of venogenic impotence, characterized as it is by transient erection, and featuring pathological cavernosograms as well as high cavernometric figures, belongs more appropriately to a clinical syndrome and is, therefore far from being unambiguous. Arterial-arterial bypass and selective veins ligation were then introduced to treat cases of "pure" arteriogenic or venogenic insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)


[Endocrine therapy of sexual impotence in men]. Male sexual activity is in all mammalian species, included man, androgen-dependent. The role of testosterone (T) starts already during intrauterine life. It continues thereafter, inducing the development of sexual secondary characteristics and libido. Therefore T has represented the "classical" treatment of male sexual dysfunctions. In the therapeutic routinary use T is employed ad ester, like cipionate, enanthate and other i.m., undecanoate per os. When a pituitary defect is present and the testicular receptors are functioning a treatment with HCG can be employed.


[Medical treatment and impotence].

[Medical treatment and impotence]. After having emphasized the importance of interdisciplinary diagnostic approach to the sexual impotence as a symptom and having made some comments about the erection's physiology, the Authors, according to their experience, take drugs into consideration for elective treatment of sexual intercourse.


[Treatment of psychogenic impotence].

[Treatment of psychogenic impotence]. Individual, marital or familiar problems, life circumstances, lack of libido, anxiety or sex identity fragility or immaturity may determine or make worse the erectile deficit. A thorough diagnostic work up is essential for the prognosis and the choice of the more fitting therapy. Emotional and cognitive understanding of the psychogenic background of the symptom is combined with behavioral therapy based on modern principles of neuroriabilitation.


[Intracavernous infusion of drugs].

[Intracavernous infusion of drugs]. In 1982 Virag presented the initial experience of use in diagnosis and treatment of impotence. PGE1 has been showed a safe and effectiveness drug. From september 1989 to october 1991 210 patients with erectile disorders were managed by I.C.I. with PGE1 with minimal side effects.


[Non-surgical therapy of impotence: infiltration, iontophoresis, ultrasound, laser]. Surgical therapy is the only useful correction in congenital fibrosis or in hypoplasia of the 'corpora cavernosa', associated with hypospadia or not. On the contrary in not congenital fibrosis of the 'corpora cavernosa' (Peyronie's disease, consequences of priapism, or trauma, complications of pharmaco-prosthesis) are allowed pharmaco-physical treatments (infiltrations, ionophoresis, ultrasound, laser). Pharmaco-physical therapy can be used as the only treatment, which is often resolutive, but it is also useful before or after the surgical operation of the 'corpora cavernosa'. These diseases can give disorders of the erection, until complete impotence is reached. In fact the erectile tissue can't expand, because of the rising fibrosclerosis. Among acquired fibrosis of corpora cavernosa I.P.P. has surely the greatest recurrent: the consistency of our series made possible to achieve significant results with a unified therapeutical protocol. The same management was applied in other, less frequent, penile fibrosis, always with full positive results even if on a small number of patients. We are evaluating a new drug (defibrotide) in the treatment of cavernosal vasculitis. Another one (hyaluronidase) associated to orgotein, could improve its effect against inflammation especially in chronic evolutions. Besides new treatments, we emphasize the prevention of iatrogenic fibrosis with particular regard to cavernous pharmaco-infusions by autoinjections: the training of the patient and the safety of the autoinjectors must be carefully checked by the andrologist to decrease a large amount of complications.


[Transdermal therapy of erectile insufficiency]. The introduction of intracavernosal (i.c.) administration of vasoactive drugs has revolutionized diagnosis and treatment of sexual impotence. This procedure, though, carries some risks and undesired side-effects, such as fibrosis, priapism, hematomas, etc. Thus, at our Centre has been evaluated the possibility of a transdermal (TS), either active or passive, treatment of impotence. In a first trial, double blind crossover, 62 patients have been treated with yohimbine (YOH) as ointment. About 5 mg of the drug were applied at the balanopreputial sulcus, twice daily. In 10 patients YOH was also assayed by HPLC in the blood drawn from the corpora cavernosa after the application of the drug: a rapid adsorption of the drug was demonstrated and a peak value of 58 ng/ml at 25 min. Treatment with YOH was particularly satisfactory in patients with impotence of recent onset and mild degree, that is without major vascular alterations. The active TD drug administration was tested with papaverine delivered with cavernous bodies by a C.T.D.A.S. (Controlled Transdermal Drugs Administration System). Thin layer chromatography has shown the passage of about 10% of patients a relevant amelioration of erectile function was observed.


[Vacuum therapy].

[Vacuum therapy]. In the therapy of vasculogenic impotence, the Vacuum Device has been proposed up to now as an "external" prosthesis device with the aim of obtaining a penile erection of sufficient rigidity for penetration, in patients afflicted by vascular or neurological disorders. In the eighties, the experience gained with the use of Intra Cavernous Injections (C.I.D.) (using papaverine, phentolamine and prostaglandin), demonstrated not to be an exclusively palliative therapy ("pharmacological prosthesis"), but to represent as well a sort of "vasoactive exercise" of the erectile tissue. In the nineties, many wondered what could be a valid alternative to the C.I.D. Taking this into consideration, we modified the method of application of Vacuum Therapy. The device was used once a day without the constrictive band applied to the penis root, in order to generate a passive action on the erectile tissue, a sort of "stretching" for the smooth muscle fibers. From January 1990 to December 1991, we treated 78 pts. afflicted by erectile failure. The patients were divided into 3 groups (26 each) of distinct therapy: the first was treated weekly with only endocavernous papaverine administration (20 mg.), the second underwent daily Vacuum Therapy exclusively (10'-15') and the third received a combined therapy: Vacuum Device, daily and C.I.D. with Papaverine (20 mg.) once a week. The results of this treatment are as follows: the patients who underwent Vacuum Therapy daily (2nd and 3rd groups) showed, at the end of the treatment (6 months), a significant improvement in spontaneous erectile ability (14 Pts.-53.8% in the 2nd group; 17 Pts-65.3% in the 3rd group).(ABSTRACT TRUNCATED AT 250 WORDS)


[Postoperative impotence].

[Postoperative impotence]. Increasing interest has developed in recent years about the preservation of sexual function after urological surgery. The pelvic plexus which is formed by parasympathetic visceral efferent preganglionic fibers that arise from the sacral center provides autonomic innervation to the corpora cavernosa. The cavernous nerves emerge from the pelvic plexus and then travel along the posterolateral portion of the seminal vesicle and prostate and then along the membranous urethra. The preservation of the nerve supply of the corpora during urological and pelvic procedures is of vital importance to preserve potency.


[Treatment of gas gangrene. Results of a retro- and prospective analysis of a traumatologic patient sample over 20 years]. From 1970 to 1977 and from 1978 to 1990, the treatment and outcome in 136 patients with gas gangrene were investigated. The prognosis was better in patients with gas gangrene after trauma than in patients with gas gangrene resulting from vascular insufficiency or malignant tumours. In the first group the lethality of gas gangrene was 28.6%, in the second group, 7.1%. This difference is significant (P < 0.05). In 40.5% the infected extremities were saved. Patients with injuries without fractures did not lose limbs because of gas gangrene or die of it. When an operation was performed before or after the first session of oxygenation at high pressure (OHP) lethality was lower (20%) and the rate of saved limbs higher (80%) than with later operation (lethality, 50%; saved limbs, 45.5%). All patients who could not be treated by OHP, or only once or twice, died. From 1970 to 1977 patients who were treated surgically and received OHP for 5 days survived, and since 1978 this has applied to patients treated for 4 days. In general, the lives of patients with gas gangrene are no longer in danger by the 5th day of therapy. The use of checklists for diagnosis and therapy has been practised since 1978, and this is assumed to be one factor in the better outcome.


[Experimental studies of thermal disinfection and sterilization of allogeneic bone transplants and their effects on biological viability]. Thermal energy (80 degrees) for the disinfection of cancellous allogenic bone grafts was employed, and it proved to be an advantageous, safe and easily accessible method. The effects of this treatment on biological values were examined in terms of biomechanical and biodynamic (graft incorporation) loss of the treated grafts versus the autoclaved and untreated samples. Given the thermolability of the pathogens in question, the thermal approach presented here has the advantage of being readily controllable. The lack of toxic or mutagenic risks through this method and its accessibility represent further advantages. In thermal treatment of bone allografts, it is essential that one knows the thermoconductivity of the bone sample and that one can demonstrate pathogen inactivation through the entire graft volume. All of the parameters in the 80 degrees C group that were measured in this study indicate clear biological superiority over the autoclaved group. A newly developed thermoincubator is introduced for gentler disinfection of allogenic bone grafts and it inactivates common vegetative pathogens as well as HIV. It is still necessary to conduct serological screening for hepatitis antigens in the donor pool, however. Based on these results, we conclude that the clinical use of autoclaved allogenic bone grafts needs to be reviewed and possibly limited.


[HIV detection in the bone transplant with polymerase chain reaction]. In trauma surgery, bone transplantation was needed in nearly 15% of all operations for reconstruction of defects. A high risk of viral infection remains in transplantation, however, cocultivation procedures have shown that human immunodeficiency virus (HIV-1) resides in bone of HIV-infected persons. Safety guidelines for running bone banks were not always easy to follow, and physical or chemical procedures applied for disinfection failed to inactivate HIV-1. In the present study we show that the polymerase chain reaction technique is an appropriate and sensitive means of detecting the HIV-1 genome in bone material prior to transplantation and-used in this way-can help to diminish the risk of HIV-1 transmission via bone transplantation.


[MEDKOM--new perspectives for accident surgery?]. MEDKOM is a new communication concept in trauma surgery, originally inaugurated as a multi-user online video communication system and now proving its benefits in medicine. The technological conditions needed and its daily usefulness are described, and examples from our clinic are given. The importance of modern technology and the possibilities it opens up, especially for medical training programmes and quality protection in trauma care, are pointed out.


[Experimental trial of intraoperative spinal ultrasound]. Dorsal operative stabilization of spinal fractures by internal fixation is an established means of treatment directed at releasing the extrinsic compression of the intraspinal contents caused by the fractured posterior surface of the vertebral body. There are few ways of assessing how successful the repositioning is intraoperatively. Intraoperative ultrasound with a special small transducer is possible, but it is difficult to reach the intraspinal area by this means, because it is surrounded by bones. A laminectomy would destabilize the injured vertebral column even further. By experiments performed on six human vertebral columns we show that it is possible to view the entire length of the fractured posterior surface by ultrasound. The beam has to be projected between the laminae vertebrae following a small laminotomy. Preliminary intraoperative experiences with eight patients confirm our experimental results. The intraoperative ultrasound results have been confirmed by preoperative and postoperative CT. We expect the necessity for laminectomy for examination of the posterior surface of the vertebral body to decline in frequency in the near future.


[Temporary balloon catheter occlusion for control of bleeding of a blunt injury of the proximal axillary artery. Case report and review of the literature]. We describe the successful placement of an intra-arterial balloon catheter by a femoral approach in order to occlude the proximal arterial end and to control massive bleeding in a patient with rupture of the left axillary artery after blunt scapulo-thoracic dissociation. To our knowledge this technique has so far not been reported in Europe. It allows rapid control of bleeding, minimizes blood loss and markedly facilitates pre- and perioperative management in selected cases. The authors review the relevant literature dealing with this topic.


[Double dislocation of a finger (personal cases and contributions from the literature)]. This is the author's third report on this extremely rare injury. New cases are discussed, and a review of observations is given on the basis of the author's experience and that of others.


[Management of femoral neck fracture in advanced age using femur head endoprosthesis]. Between 1984 and 1989, 419 patients with subcapital fracture were treated, 170 with a head conserving method, 57 with a total endoprosthesis (THR), and 242 with a hemiprosthesis. In the last group the average age was 80.1 (range 55-98) years. At follow up an average of 2.5 years after surgery 63.3% had died. Most of the remaining patients were asymptomatic and their walking ability in the first few years was good. Complications included head protrusion, followed in declining order of frequency by loosening and ectopic calcifications. We conclude that for elderly patients this technique is a suitable alternative to THR or the femoral-head-conserving method, which had higher complication rates.


[Results of repositioning osteotomies in delayed healing or pseudarthrosis of the proximal femur]. The results after valgus osteotomy for delayed or nonunion in 20 patients with femoral neck fractures (9 Pauwels type II and 11 type III) and 10 intertrochanteric fractures are reported. The mean age of the patients at presentation with delayed/nonunion of femoral neck fractures and intertrochanteric fractures was 37.5 and 60 years, respectively. The average interval between injury and valgus osteotomy in the first and second group was 8 and 13 months, respectively. The average size of the preoperatively determined and intraoperatively removed wedge was 30 degrees in both groups. The results of the two fracture groups were analyzed separately. All but one osteotomy in a patient with a nonunion of a femoral neck fracture consolidated without complications. This case developed a nonunion at the osteotomy and required additional surgery consisting of bone graft and refixation to heal. Of the femoral neck delayed/nonunion cases, 15 (75%) healed immediately following valgus osteotomy. In the intertrochanteric delayed/nonunion patients, valgus osteotomy led directly to bone consolidation in 6 (60%). In each fracture group 3 additional cases healed following reoperation for a total consolidation rate of 90%. In the femoral neck group one union was complicated by infection, resulting in ankylosis of the hip and 3.5 years later another patient with a revascularized femoral head required total hip arthroplasty because of a large, loose osteochondral fragment. In two cases union of the former femoral neck fracture could not be achieved. Partial avascular necrosis determined the course and total hip arthroplasty was required for both cases.(ABSTRACT TRUNCATED AT 250 WORDS)


[Arterial occlusive disease after surgical treatment of fractures of the lower extremity]. Chronic arterial occlusive disease of the lower limb may complicate fracture treatment. In five cases, diagnosis of vascular disease was established when delayed fracture healing or skin gangrene occurred some weeks after operative fracture treatment. The diagnosis of vascular disease was made from the case history, examination of the patient and repeated pulse control at the feet. Arterial insufficiency will be worsened by long-term elevation of the leg and by fracture treatment with a cast or traction. Angiography is indicated, and quick vascular reconstruction is recommended. In one patient with known iliac occlusion (Leriche syndrome) we performed simultaneous vascular reconstruction and operative fracture treatment.


Evaluation of coronary artery disease with positron emission tomography. Positron emission tomography (PET) represents the most sophisticated imaging modality in nuclear medicine allowing quantification of regional tracer tissue concentrations. Beside the technical superiority of data acquisition, a large number of PET radiopharmaceuticals are available for clinical application. Based on currently available data, PET provides detection of coronary artery disease with higher diagnostic accuracy than conventional thallium-201 single positron emission computed tomography. Applications of PET with metabolic tracers have been shown to provide clinically important information in the management of patients with advanced coronary artery disease. Metabolic tissue characterization represents the most specific definition of tissue viability currently available. However, the relatively high cost of the technology and the lack of reimbursement by major insurance carriers has limited widespread clinical application. In addition to the acceptance of PET as an advanced clinical imaging modality, this imaging modality excels as a sophisticated research tool assessing specific tissue functions that could not be visualized before in the living human heart. Without doubt, this technique will contribute significantly to the future characterization of pathophysiological alterations in substrate metabolism and other physiological processes such as autonomic innervation. Furthermore, the kinetics of radiolabeled cardiac drugs may be studied with PET to provide objective characterization of cardiovascular drug effects and thus enhance our understanding of pharmacokinetics in the human heart.


Positron emission tomography in cerebrovascular disorders. The introduction of positron emission tomography (PET) as a powerful imaging modality has played a major role in the understanding of the pathophysiological bases for cerebrovascular disorders. PET is the only technique that allows measurement of regional cerebral blood flow, blood volume, oxygen extraction fraction, and oxygen and glucose metabolism with detail and accuracy. Using PET, these physiological parameters can be measured to determine the extent of the disease from the early stages of cerebrovascular disorders to acute cerebral infarction. Significant hemodynamic and metabolic abnormalities are noted in chronic ischemia, but no structural changes are noted on anatomic images. PET studies have shown that in many patients in the early phases (10 to 12 hours) of clinically diagnosed acute stroke, a substantial area of ischemia exists, which, if untreated, will become irreversibly damaged. Similar to the results achieved in patients with acute myocardial infarction, appropriate intervention in patients with cerebrovascular disorders may significantly reduce the extent of injury to the brain. PET also has been useful in predicting functional recovery and monitoring the effects of various therapeutic approaches. Although functional imaging of the brain with single photon emission computed tomography can successfully be used in the investigation of several disorders of the brain, its role in cerebrovascular disorders is quite limited. PET is a unique modality that studies ischemic diseases of the brain, and it potentially could play a significant role in the management of patients with cerebrovascular disease. This will be further realized when aggressive approaches are used routinely in the future.


The use of positron emission tomography in the clinical assessment of dementia. A number of reasons can be cited for performing a test that identifies patients early in their course who have fatal and currently untreatable neurological disorders. At this stage of illness there is clinical ambiguity. The patient, family, and physician are typically faced with a battery of negative test results and an ambiguous clinical impression that can lead to periodic repetition of tests that involve cost, inconvenience, potential morbidity to the patient, and lack of definitive diagnosis. An accurate test would lead to the avoidance of these low-yield, repetitive, and costly evaluations. In addition, such studies can identify homogeneous groups of individuals with degenerative disorders leading to dementia who could be enrolled in experimental therapeutic programs. In these programs therapies could be monitored in an objective and noninvasive fashion using positron emission tomography (PET). The magnitude of the health problems resulting from the dementing illnesses is great in terms of medical practice, economics, and family hardship. The number of individuals with these disorders is predicted to increase dramatically in the future. The ability to provide an accurate diagnosis and more clear prognosis early in the disease course should diminish ambiguity for patients, families, and physicians. Ample evidence is cited in this article to show that PET has the ability to provide such information objectively and noninvasively.


The use of positron emission tomography in the clinical assessment of epilepsy. Positron emission tomography (PET) of local cerebral glucose utilization is highly sensitive in detecting epileptogenic regions that correspond to electrographic localization in patients with epilepsy. In medically refractory temporal lobe epilepsy for which surgical resection of the epileptogenic zone is a therapeutic option, the application of PET enables more than 50% of adults and older children to be successfully operated on without the necessity for chronic intracranial electrographic monitoring. In infants with intractable infantile spasms and various types of partial epilepsy, PET has uncovered focal areas of cortical dysplasia and other anatomic abnormalities, which, after resection, have resulted in cessation of seizures and developmental improvement. The distribution of PET abnormality is in excellent agreement with the extent of the epileptogenic zone as determined by intraoperative electrocorticography, thus avoiding the necessity for chronic intracranial electrographic monitoring in 90% of these infants. As a result of PET, the preoperative evaluation of intractable epilepsy in both adults and children has become less invasive and less costly.


Neuropsychiatric disorders: investigation of schizophrenia and substance abuse. Because neuropsychiatric disorders involve functional and neurochemical cerebral abnormalities, positron emission tomography (PET) is ideally suited for their investigation. The use of tracers to measure regional brain glucose metabolism and/or blood flow has allowed the evaluation of brain function in psychiatric patients. The use of radioligands to assess receptor concentration has enabled an evaluation of the extent to which specific neurotransmitter systems are involved in the pathogenesis of mental illness. This article reviews the application of PET technology to the understanding of schizophrenic disorders and substance abuse.


The role of positron emission tomography in oncology and other whole-body applications. Imaging and quantifying biochemical and physiological processes with PET clearly has major potential significance for all organ systems and many disease states. Although the full utility and potential of emerging new applications of PET in organs other than the heart and brain must be demonstrated in basic and clinical research studies, the rapidly accumulating aggregate experience in oncology in particular, and in other organ systems and disease states as well, indicates that PET is now truly becoming a modality of both clinical and investigative use for the body as a whole as well as for specific organ systems. Whole-body PET FDG imaging (Fig 9) illustrates the potential of biochemical imaging to map the distribution of cancer throughout the body. With the growing list of radiopharmaceutical and quantitative techniques applicable to cancer studies with PET, this field will continue to realize significant growth.


Position emission tomography at the turn of the century: a perspective. Nuclear medicine translates advances in molecular biology into the care of patients. In the future, diseases will be characterized at the molecular rather than the cellular level, often before detectable structural changes have occurred. Position emission tomography (PET) will play a major role in the study of intercellular communication by making it possible to characterize the actions of "molecules with messages." Diseases will be characterized by defects in intercellular communication. Treatment will be planned based on molecular abnormalities, and the response to treatment will be monitored with molecular probes. PET studies of the brain, heart, and cancer will be extended to all organs of the body. Pharmacology will be strongly influenced by PET because most drugs act by stimulating or blocking "recognition sites" on the surface of cells. In the next century, will single photon emission computed tomography (SPECT) makes PET unnecessary? The answer is no, because both PET and SPECT will have achieved a permanent role in medical practice; both make it possible to examine regional in vivo chemistry in human beings. Carbon-11 and fluorine-18 will continue to lead the way, but many drugs, and some body constituents such as proteins, can be radiolabeled with iodine-123 and technetium-99m. Today, PET is limited by the need to make one's own radiotracers. This is likely to change when regional radiopharmacies become widespread.(ABSTRACT TRUNCATED AT 250 WORDS)


Regulation of hepatic gene expression and development. Tissue-specific expression in the hepatocyte appears to require the actions of multiple factors in specific combinations for each gene. The interactions between two or more positive-acting factors that raise transcription to optimal levels and those between positive and negative factors that enforce strict cell-specific transcription remain to be elucidated. However, recent progress in the identification and cloning of the genes for many of these factors will make it possible to begin to answer these important questions.


Cellular and molecular mechanisms of hepatocarcinogenesis. For colorectal carcinomas, the rate of tumor development is proportional to the fourth to sixth power of elapsed time, suggesting that four to six independent events are necessary. Although similar calculations have not been made for HBV-associated HCCs, it is likely that this is also the case for HCCs, since individuals with persistent HBV infection do not usually develop HCC until they are 45 or greater years old. As evidence for specific genetic and epigenetic changes in HCCs accumulate, the important players in multistep hepatocarcinogenesis are becoming clearer. However, even though Myc family oncogenes are clearly implicated in woodchuck HCC, similar integrations have not been found in human HCCs. Therefore, although rodent and human systems have many similarities, we must realize that important differences may also exist. Regarding tumor suppressor genes, the evidence for p53 alterations in HCC is strong. A growing body of evidence suggests further that alterations in the retinoblastoma gene and one or more tumor suppressor genes on chromosome 11 are also involved in HCC. HBV integrations may certainly play a role in the generation of chromosome aberrations leading to loss of tumor suppressor alleles, since chromosomes 11 and 17 are the most common integration sites. Finally, the role of X proteins as participants in malignant transformation has been demonstrated for certain immortalized, nontransformed hepatocytes. Altered autocrine mechanisms of cell growth control, possibly involving IGF-II, are clearly implicated in HCC. Paracrine mechanisms for the control of hepatocyte growth and differentiated functions may also be altered as a result of the synthesis and secretion of a complex array of interleukins, HGF, and basic and acidic FGFs by cells in the inflammatory and cirrhotic lesions of precancerous livers. Whether the order of molecular changes in the hepatocyte is important for malignant progression is presently not clear. What is clear, however, is that hepatocarcinogenesis involves alterations in the concerted action of protooncogenes, growth factor, and tumor suppressor genes. How these factors interact will provide a more complete understanding of the mechanism or mechanisms of hepatic oncogenesis.


New strategies for isolation of low abundance viral and host cDNAs: application to cloning of the hepatitis E virus and analysis of tissue-specific transcription. The ability to clone viruses molecularly has led to dramatic advances in our understanding of this diverse group of agents at the molecular level. These insights are critical to the development of experimental strategies for the containment and control of the various viral pathogens that cause hepatitis in man. Knowledge of the genes and gene products have, for example, assisted in the design of expression systems that have been useful for the cell-free expression and production of viral constituents in the development of a subunit (recombinant) vaccine for HBV. Of particular advantage to the experimenter would be the ability to clone the virus directly from the infectious source without the need to resort to biologic amplification systems that require costly investments of money and manpower. This would obviate the need for the time-intensive development of a tissue culture propagation or the expensive cost of developing an animal model. The methods described here have applications to the discovery and isolation of low abundance transcripts from host (cellular) genes. These host encoded products may have important roles in virus replication and certainly by themselves constitute a growing area of study. The direct selection protocol has already proven its value in the isolation of novel (previously undescribed) gene sequences from complex cellular sources. The application of these methodologies should, at the single cell level, aid in the delineation of those important host-encoded gene products that are critical for the efficient in vitro propagation of hepatotropic viruses. The identification of these low abundance cellular genes will elucidate the biologic interplay between host and obligate intracellular parasite (virus) and potentially lead to the development of new strategies for virus control that take into consideration the role of the cell as host.


Molecular biology and genetics of alpha 1-antitrypsin deficiency. The use of advanced recombinant DNA technology has provided an improved understanding of the human AAT deficiency phenotype by providing the amino acid sequence of several variant proteins and by allowing for the production of various cell and animal models to study the molecular and biochemical components of the retention, degradation, and accumulation of these variants in the hepatic ER. Human AAT deficiency will continue to serve as an excellent model for enhancing our current understanding of mechanisms utilized in regulating protein "traffic" in the ER and in elucidating the pathophysiologic components of AAT-related liver disease.


Hepatocyte transplantation: development of new systems for liver repopulation and gene therapy. Following recent advances in molecular and cell biology, development of hepatocyte transplantation has been considerably invigorated. To study the fate of hepatocytes transplanted into the liver, new strategies have included the use of endogenously marked transgenic hepatocytes. Release of peripherally quantifiable marker proteins by transgenic hepatocytes has provided noninvasive ways to determine hepatocyte engraftment and prolonged survival. Further characterization of intrasplenic hepatocyte transplantation has established this to be the most suitable method for targeting hepatocytes to the liver. Advances in gene cloning, retrovirology, and gene transfer technology have provided further tools for accomplishing gene therapy. Practical strategies for ex vivo gene therapy involving hepatocytes have been developed by exploiting these new technologies. The potential value of hepatocyte transplantation in acute hepatic failure has begun to be reexamined. Therefore, hepatocyte transplantation can be predicted to provide new ammunition for continuing our assault on untreatable disorders. Resolution of outstanding issues should accelerate this process.


End-stage liver disease in a 31-year-old man. This is a case of decompensated chronic liver disease associated with FZ phenotype AAT deficiency. Histologic confirmation of the diagnosis was aided by immunostaining of the AAT globules. Liver transplantation was successful in reversing the disease process.


Evaluation of cervical vertebral injuries. The use of imaging studies on patients with suspected cervical vertebral injury should be restricted to those patients who fall into the high-risk category for injury. Once a decision is made to obtain radiographs, a minimum of five views is required to adequately rule in or rule out injury. Complex imaging studies such as CT, polydirectional tomography, and MRI may be performed to confirm the initial impression based on plain radiographic findings. The diagnosis of cervical injuries may be facilitated by following a logical pattern of analysis searching for abnormalities of alignment and anatomy, of bony integrity, of the cartilage or joint spaces, and of the soft tissues. This ABCS approach should simplify an intimidating subject and insure a confident radiological diagnosis.