Ethnic variation in vitamin D-binding protein (GC): a review of isoelectric focusing studies in human populations

Summary Since the discovery in 1977 that the GC1 gene could be resolved into two common subcomponents on an isoelectric focusing (IEF) gel, a large number of ethnic groups have been screened to analyze the extent of genetic variation in human populations. Using the IEF technique, approximately 50,000 individuals from 160 different populations have been tested for the GC polymorphism. A marked variation in common GC suballele frequencies in different geographic areas seems to correlate with skin pigmentation and intensity of sun light. Pigmented (black) and keratinized (yellowish) skin type populations have a relatively high frequency of the GC ^*IF allele as compared to white skin populations. By comparison non-pigmented and non-keratinized white skin populations are generally characterized by having the maximum values of the GC ^*IS allele. The anthropologic significance of the GC locus has been enhanced further by detecting additional unique GC variants which provide useful information about evolutionary links between different populations. However, the presence of some electrophoretically identical unique variants in genetically and geographically distinct populations demand further investigation of these allelic variants to shed more light on their origins.     

8q24.12 Interstitial deletion in trichorhinophalangeal syndrome type I

Summary In the present report we present the first example of a small interstitial 8q24.12 deletion in a patient with trichorhinophalangeal syndrome type I.     

Bloom's syndrome

Summary The biochemical defect in Bloom's syndrome (BS) remains unknown, but two characteristic features of BS cells point to a disturbance of DNA replication, namely, an excessive number of sister-chromatid exchanges (SCEs) in bromodeoxyuridine (BrdU)-substibuted cells and an abnormally slow rate of replicon elongation. The hypothesis of an abnormal DNA polymerase as the explanation for these observations was tested using an in situ assay system for DNA polymerase activity and to estimate molecular weights in cellular extracts of cultured BS cells. DNA polymerase subunits in cellular extracts from the BS cells when separated electrophoretically on polyacrylamide gels showed the same mobilities (i.e., molecular weights) as the controls and were equally effective at promoting the incorporation of isotopically labeled nucleosides. It is concluded that the genetic defect in BS has no direct effect on either DNA-polymerase activity or the amounts and molecular weights of the different forms of the enzyme.     

Cell envelope phospholipid changes in a moderate halophile during phenotypic adaptation to altered salinity and osmotic stress

Abstract The increased content of negatively-charged phospholipids in membranes of Vibrio costicola grown at high salinities is mediated by increased phospholipid synthesis of phosphatidylglycerol relative to phosphatidylethanolamine. This phenomenon provides a system for investigating the factors involved in triggering and controlling haloadaptation in this moderately halophilic bacterium. We review recent experiments, which show that when subjected to sudden increases in external salinity, V. costicola senses both the absolute NaCl concentration and the magnitude of the salt shift. We show that the latter is sensed at least in part via osmotic pressure effects, since shift-up into sucrose-containing media triggers comparable changes in growth and in phospholipid composition and synthesis.     

Antigenic similarity of microorganisms to human group-specific blood factors and the immune response of persons with various ABO classifications

The isohemagglutination test with the introduction of the heat-stable fraction of microbial broth culture into the reacting system was used as a model of the antigen-antibody interaction. In the "A-anti-A" system the inhibition of isohemagglutination in the presence of staphylococcal allergen was observed. This inhibition was caused by the binding of the allergen with anti-A-antibodies, which was indicative of the antigenic similarity between staphylococcus and group-specific factor A. The influence of the similarity thus established on immune response was studied by the determination of antitoxic titers in 292 donors immunized with staphylococcal toxoid and in 86 patients with chronic hematogenic fistulous osteomyelitis with due regard of the ABO phenotype of the examinees. Subjects with group A(II) blood were found to have lesser antibody titers than those with blood of other groups and to be predisposed to the progressive course of staphylococcus-induced diseases.     

Cellular ultrastructure of the meningococcus when incubated in a continuous culture of human FL-line amnion

Some details of the ultrastructure of several meningococcal strains having had contacts with cells in continuous human amnion cell culture FL for 6 hours to 2 days have been defined with greater precision by means of electron microscopy. The study has shown that the contact of meningococci with the tissue culture is accompanied by the appearance of meningococcal forms with the defective cell wall, similar to L-forms: spheroplast, protoplast, gigantic cells and microcells, as well as budding variants. The meningococcal variants with the defective cell wall, appearing in the cell culture, and the forms occurring (in different proportions) in "ripe" meningococcal populations developing in the culture media for a long time and isolated from a human body have been found to have no essential differences in their fine structure. These data indicate that any external influences (meningococci are highly sensitive to such influences) produce sufficiently rapid changes, similar to L-transformation, in the fine structure of these microorganisms.     

Antigens associated with various cytotoxic activities of murine peripheral macrophages

BCG- or glucan-elicited murine peripheral macrophages released a cytotoxin in the presence of loach egg lectin, whereas proteose peptone-, glycogen-, or thioglycollate-elicited or resident macrophages did not. The macrophages that released cytotoxin coincided with those that showed lectin-dependent macrophage-mediated cytolysis (LDMC) in response to loach egg lectin. The cytotoxin released by BCG-elicited macrophages in response to loach egg lectin had a molecular weight of 55 K daltons. The macrophages that released cytotoxin and other cytotoxic macrophages such as those that showed LDMC- and antibody-dependent macrophage-mediated cytolysis (ADMC) were examined by using several antibodies to surface antigens of macrophages. The results showed that murine peripheral macrophages could be divided into three types. Resident macrophages (Type I) which had common macrophage antigens (Mac-1 and B12) showed only LDMC in response to wheat germ agglutinin. Some elicited macrophages (Type II) were asialo GM1-positive and showed both ADMC and LDMC in response to wheat germ agglutinin. Activated macrophages (Type III) showed LDMC in response to loach egg lectin and cytotoxin-release, but had no antigen detectable with monoclonal anti-macrophage antibody (C14). These three types of macrophages were clearly distinguished diagrammatically by their roof-shaped, rocket-shaped and irregular-shaped profiles of activities and antigens. These data suggest that several selected surface antigens of macrophages are associated with distinct cytotoxic stages of peripheral macrophages.     

Cytogenetic activity of metabolites of pesticides representing different classes of chemical compounds

The cytogenetic activity of some substances formed in agricultural plants during metabolism of pesticides of four classes of chemical compounds was studied in the culture of human peripheric blood lymphocytes. Metabolites were shown either to have mutagenic properties similar to those of the initial compounds (ziramtetramethylthiourea, both being mutagens; captan-phthalimide, both possessing no cytogenetic activity) or to be considerably transformed in comparison with them as a result of deactivation (benomile-MBC) or activation (betanal-MHPC) processes. The latter variant if being determined for the genetic hazard of the pesticide necessitates to take into account data on the mutagenic character of those metabolites which really might enter the human organism.