Search PubMed⌕ Search

Biomedical subjects

H Walter

Publications and source records attributed to H Walter.

At least 235 records · Page 13Linked to original sources
PubMed1983

Transferrin subtypes in four Northwest Indian tribal populations and some remarks on the anthropological value of this new polymorphism.

Serum samples from four tribal Populations--Chaudhuri, Kotwalia, Vasava, Gamit-living in Gujarat (Northwest India) were tested for transferrin subtypes. The results are compared with those reported for other Indian populations. Reviewing all the hitherto published Tf subtype data some interesting racial differences in the distribution of gene frequencies emerge. A possible geographical distribution pattern of the variants is explored.

Alleles↗
PubMed1983

Detection of surface differences between two closely related cell populations by partitioning isotopically labeled mixed cell populations in two-polymer aqueous phases. I. Human red blood cell subpopulations.

The partition behavior of cells in dextran-poly(ethylene glycol) aqueous phases (i.e., the cells' relative affinity for the top or bottom phase or their adsorption at the interface) is greatly dependent on the polymer concentrations and ionic composition and concentration. Appropriate selection of phase system composition permits detection of differences in either charge-associated or lipid-related surface properties. We have now developed a method that can reveal differences by partitioning that fall within experimental error if one were to compare countercurrent distribution (CCD) curves of two closely related cell populations run separately. One cell population is isotopically labeled in vitro (e.g., with 51Cr-chromate) and is mixed with an excess of the unlabeled cell population with which it is to be compared. The mixture is subjected to CCD and the relative specific radio-activities are determined through the distribution. As control we also examine a mixture of labeled cells and unlabeled cells of the same population. The feasibility of this method was established by use of cell mixtures the relative partition coefficients of which were known. The procedure was then used to test for human erythrocyte subpopulations. 51Cr-chromate-labeled human young or old red blood cells were mixed with unfractionated erythrocytes and subjected to CCD in a phase system reflecting charge-associated properties. It was found that older cells had a high, young cells (probably only reticulocytes) a low partition coefficient. Because of the small differences involved these results were not previously obtained. It was further determined, by repartitioning 51Cr-labeled cells from the left or right ends of a CCD of human red blood cells admixed to unlabeled unfractionated erythrocytes, that a subpopulation with higher partition coefficient exists (probably constituting the old red cells). These experiments serve to illustrate (a) that human red blood cells, contrary to a previous report, can be subfractionated by partitioning and (b) the usefulness of this new method in detecting smaller surface differences between closely related cell populations than was heretofore possible by partitioning alone.

Cell Separation↗
PubMed1983

Detection of surface differences between two closely related cell populations by partitioning isotopically labeled mixed cell populations in two-polymer aqueous phases. II. A correction.

The partition behavior of cells in dextran-poly(ethylene glycol) aqueous phases (i.e., the cells' relative affinity for the top or bottom phase or their adsorption at the interface) is greatly dependent on the polymer concentrations and ionic composition and concentration. Appropriate selection of phase system composition permits detection of differences in either charge-associated or lipid-related surface properties. We have now developed a method that can reveal differences by partitioning that fall within experimental error if one were to compare countercurrent distribution (CCD) curves of two closely related cell populations run separately. One cell population is isotopically labeled in vitro (e.g., with 51Cr-chromate) and is mixed with an excess of the unlabeled cell population with which it is to be compared. The mixture is subjected to CCD and the relative specific radio-activities are determined through the distribution. As control we also examine a mixture of labeled cells and unlabeled cells of the same population. The feasibility of this method was established by use of cell mixtures the relative partition coefficients of which were known. The procedure was then used to test for human erythrocyte subpopulations. 51Cr-chromate-labeled human young or old red blood cells were mixed with unfractionated erythrocytes and subjected to CCD in a phase system reflecting charge-associated properties. It was found that older cells had a high, young cells (probably only reticulocytes) a low partition coefficient. Because of the small differences involved these results were not previously obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Surface properties of lymphocyte subpopulations in autoimmune NZB/NZW F1 hybrid mice: alterations correlated with the immunodeficiency of aging.

Partitioning in a two-polymer aqueous phase system was used to probe the surface properties of lymphoid cell subpopulations in aged male NZB/NZW F1 hybrid (B/W) mice, an important model of autoimmunity, immunodeficiency, and lymphoid malignancy. Spleen cells were fractionated by countercurrent distribution (CCD, a multiple-step extraction procedure) in a charged dextran-polyethylene glycol system. CCD of spleen cells from young, clinically normal male B/W mice yielded several broad distribution patterns which frequently had two or more peaks. Analysis of differentiation antigens and functional properties of cells from different parts of the distribution revealed a subfractionation of the three major lymphocyte subpopulations. B lymphocytes had a low partition coefficient (K); T cells had an intermediate K and null cells had the highest K. To examine the partitioning behavior of T lymphocytes, spleen cells which were nonadherent to nylon wool columns were subjected to CCD. Nonadherent cells from young B/W mice consistently gave a single peak with high K. Aged mice (18 months) usually had nonadherent cells with a predominantly low K. In some experiments a systematic increase in the number of these cells could be demonstrated with increasing mouse age. An analysis of the adherence and partitioning behavior of lymphocyte subpopulations revealed no change in the adherence properties or proportions of B lymphocytes in aged mice. The large proportion of cells having a low partition coefficient in the nonadherent spleen cell population of old mice appears to be due to an increase in the number of null cells and in a decrease in the K of some T lymphocytes.

Aging↗
PubMed1983

Production, characterization and clinical application of antisera to cortisol.

In the present paper the production of highly specific and sensitive antisera to cortisol is described. The antisera were generated in rabbits using both cortisol-3-monooxime and cortisol-3,20-dioxime derivatives. Bovine thyroglobulin was used as a carrier protein. Antibody characteristics were determined by radioimmunoassay procedure. Antibody titers observed after immunization with the monooxime conjugate were significantly higher (p less than 0.001) than those obtained with the dioxime conjugate. In addition, cross reactivity for various naturally occurring steroids was markedly lower and sensitivity was increased as compared to dioxime antisera (15 vs. 40-60 pg/tube). Accuracy and precision were calculated for the monooxime antiserum used in a RIA system for clinical application. A close correlation (r = 0,9802) was found between plasma cortisol values measured by radioimmunoassay and the competitive protein binding method. The concentrations obtained by the protein binding method were slightly but significantly higher than those measured by radioimmunoassay indicating higher specificity of the antibody used (p less than 0.005).

Aldosterone↗
PubMed1983

Blood group, serum protein and red cell enzyme polymorphism in Filipinos.

144 Filipinos living in the Federal Republic of Germany have been typed for 18 polymorphic blood group, serum protein and red cell enzyme polymorphisms. The results are compared with those reported for other population samples from the Philippine. It could be shown that within the Filipino populations a considerable genetic heterogeneity is present. Finally, genetic distance measurements have been performed in order to evaluate the degree of genetic similarity with Southeast Asia.

Adult↗
PubMed1983

Population genetical investigations on Indian tribals. Preliminary report.

Data on the distribution of genetic markers in Indian tribal populations as well as in Southwest and Southeast Asiatic populations have been recorded in order to study comparatively the extent of genetic similarity and dissimilarity, respectively, 1. within the various regional tribal groups, and 2. among tribals and the populations from Southwest and Southeast Asia. The--preliminary--results of these comparisons are discussed considering the racial history of the Indian subcontinent.

Asia↗
PubMed1982

Subfractionation of cell populations by partitioning in dextran-poly (ethylene glycol) aqueous phases. "Discriminating" and "nondiscriminating" systems.

Partitioning of cells in dextran-poly(ethylene glycol) aqueous two-phase systems depends on the interaction between the surface properties of the cells and the physical properties of the phases. The latter can be manipulated to a considerable extent by selection of polymer concentrations and ionic composition and concentration. If salts (e.g., phosphate) are used that have an unequal affinity for the two phases, an electrostatic potential difference between the phases results and, at appropriately high polymer concentrations, the partition coefficient of cells is determined predominantly by membrane charge-associated properties. By "balancing" the magnitude of the electrostatic potential difference against that of the interfacial tension (primarily a function of polymer, but also phosphate, concentrations) one can obtain phase systems that give usable partition coefficients for most cell populations (1). In work under way in our laboratory on the effects of different chemical and enzymatic modifications on the relative surface properties of rat red blood cells of different ages, we have now found that certain phase compositions did not resolve such treated cell subpopulations while other phase compositions did. Thus not all charged phase systems in which cell populations as a whole have usable partition coefficients are equally capable of detecting or subfractionating cell subpopulations. It is therefore essential, before drawing conclusions on the nonseparability of cell subpopulations, to test cell separability in charged phase systems of different compositions if the system initially chosen does not afford a subfractionation.

Age Factors↗
PubMed1982

Blood groups and ABH saliva secretion in Koya Dora and Konda Kammara tribes of Andhra Pradesh.

The present paper reports the distribution of blood groups and ABH saliva secretion in two Andhra tribal populations: the Koya Dora and the Konda Kammara. 100 Koya Dora and nearly 110 Konda Kammara adults of both sexes were tested for A1A2BO, MN, Rh (CcDEe) blood groups and ABH saliva secretion. The gene frequencies for A1A2BO, MN and ABH and the gene as well as chromosome frequencies for Rh (CcDEe) systems were calculated. Koya Doras show a higher incidence of A gene than B gene, while the reverse trend is seen in Konda Kammaras. Both the tribes show a high M gene frequency. No Rh(D) negative individual was found in Koya Doras, while 4.59% of Konda Kammaras are Rh(D) negative. The chromosomes CDE, CdE, cDe, cdE, Cde and cde are absent in Koya Doras, while only the four chromosomes CDE, CdE, cDe and cdE are absent in Konda Kammaras. The chromosome CDe shows the highest frequency in both the tribes. The frequency of secretors is, as usual, higher than that of nonsecretors in both the tribes. The intergroup variation between the two tribes is not statistically significant for MN, Rh (CcDEe) and ABH systems, while the difference is significant for the A1A2BO blood groups. Suitable comparisons have also been made with all the other available data from Andhra Pradesh tribal populations with respect to different systems studied. Finally Fi estimates have been calculated after Harpending et al. (1973) and Workman et al. (1974) for Koya Doras and Konda Kammaras to assess their degree of endogamy, considering the codominant systems studied, which suggest that Koya Doras are relatively more isolated than Konda Kammaras.

ABO Blood-Group System↗
PubMed1981

Aging of erythrocytes results in altered red cell surface properties in the rat, but not in the human. Studies by partitioning in two-polymer aqueous phase systems.

Aqueous solutions of dextran and of poly(ethylene glycol) when mixed give rise to two-phase systems useful in separating cells, on the basis of their surface properties, by partitioning. Depending on whether salts with unequal or equal affinity for the two phases are chosen, phases with or without an electrostatic potential difference between the phases are obtained. At appropriate polymer concentrations the former yield cell partition coefficients (i.e., the quantity of cells in the top phase as a percentage of total cells added) based on charge-associated surface properties while the latter reflect membrane lipid-related parameters. With increasing cell age, rat erythrocytes have diminishing partition coefficients in both charged and uncharged phases. Using the elevated aspartate aminotransferase levels of younger red cells as a marker, we have not found that young mature erythrocytes of human do not have the highest partition coefficient in the red cell population as they do in rat. Experiments with isotopically labeled dog red cells yield results similar to those found with human erythrocytes. Furthermore, density-separated young and old red cells from human give overlapping countercurrent distribution curves. Finally, countercurrent distribution of human red blood cells followed by pooling of cells from the left and right ends of the distribution and subjection of these cells to a redistribution gives curves that overlap with each other and with the original countercurrent distribution. This indicates that not only are human red cells not subfractionated based on possible age-related surface alterations, but also that they are not subfractionated by partitioning based on any surface parameter. These results are consistent with our previous findings that membrane sialic acid/hemoglobin absorbance is essentially constant through the extraction train after countercurrent distribution of human erythrocytes in a charged phase system; and with the recent reports of others that there is no difference in electrophoretic mobility between human young and old red cells.

Animals↗
PubMed1981

Countercurrent distribution of human peripheral blood lymphocytes: isolation of a subpopulation enriched with natural killer and K cells.

Aqueous solutions of dextran and of poly(ethylene glycol) when mixed give rise to two-phase systems suitable for the separation by partitioning of cells based on subtle differences in their membrane surface properties. Human peripheral blood mononuclear cells were obtained by centrifuging blood over Hypaque-Ficoll and removing the cells from the cushion. Clean lymphocytes were then isolated by velocity sedimentation of the mononuclear cells. Lymphocytes were subjected to countercurrent distribution (i.e., a multiple extraction procedure) in a two-polymer aqueous phase system which separates cells primarily on the bases of surface charge-associated properties. It was found that a small subpopulation of cells with highest partition coefficient (presumably highest surface charge-associated properties) contain virtually all of the natural killer (NK) and K cell activities.

Antibody-Dependent Cell Cytotoxicity↗