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Biomedical subjects

A Shalev

Publications and source records attributed to A Shalev.

72 records · Page 4Linked to original sources
PubMed1984

Specific activity of carp antisera against beta 2-microglobulin (beta 2m) and evidence for a beta 2m homologue in carp (Cyprinus carpio).

Antisera against rabbit and human beta 2-microglobulin were produced in carp (Cyprinus carpio). These antisera were found to be specific for beta 2m, and detected beta 2m epitopes in various vertebrates including guinea-pig, cow, mouse, rat, dog, horse, cat, sheep, goat, parrot, chicken and frog. In addition, these antisera were also inhibited by an extract from oyster. The differences between the reactivity of these two antisera and the ability of the anti-rabbit beta 2m to distinguish between mouse and rat beta 2m's suggested that the carp itself carries beta 2m epitopes. This hypothesis was corroborated by the ability of a variety of mammalian anti-beta 2m antisera to induce a mitogenic response in carp leukocytes. Finally, a rabbit antiserum against dog beta 2m was shown to precipitate a low molecular weight molecule from carp leukocyte extract. This molecule is likely to represent the carp homologue of mammalian beta 2m.

Animals↗
PubMed1984

Lack of beta 2-microglobulin on the surface of canine transmissible venereal tumor cells.

beta 2-Microglobulin (beta 2m) expression on the cell surface of the naturally occurring, allotransplantable canine transmissible venereal tumor (TVT) was investigated by use of indirect membrane immunofluorescence and radioimmunoassay. Two cell populations were identified in animal-derived, collagenase-disaggregated TVT cell suspensions. About 80% of the cells lacked surface beta 2m expression, whereas about 20% of the cells strongly reacted with anti-dog beta 2m serum. With the use of a cell separation technique, beta 2m-negative cells were demonstrated to carry TVT markers on their surface, whereas the beta 2m-positive cells did not express the tumor markers. The beta 2m-positive cells seemed, therefore, to be tumor-infiltrating host cells. These findings were supported by fluorescence staining studies of frozen sections of the TVT. The lack of beta 2m expression on the surface of TVT cells might explain the allotransplantability of this neoplasm, since beta 2m expression on the cell surface appeared to be obligatory for the expression of class I major histocompatibility complex antigens.

Animals↗
PubMed1983

A cell-free soluble-phase radioimmunoassay for Thy-1 antigen.

A cell-free, soluble-phase, radioimmunoassay has been developed for Thy-1 antigen. The method is based on immunoprecipitation of radiolabelled Thy-1 molecules with specific antibodies, anti-immunoglobulin serum and polyethyleneglycol (PEG). The method can be used with convenience to screen for the presence of Thy-1 in various fluids as well as on cell surfaces for qualitative or quantitative purposes. Presence of antibodies or autoantibodies against Thy-1 can also be detected specifically. Evidence that the dog, carp, hamster and goldfish carry Thy-1-like molecules on neuronal (brain) cells is demonstrated by this method.

Animals↗
PubMed1983

Evidence for beta 2-microglobulin-like and H-2-like antigenic determinants in Drosophila.

Serologic evidence for the existence of beta 2-microglobulin-, (beta 2m) like and H-2-like antigenic determinants in Drosophila are presented. Drosophila-cultured cells and larvae extract were shown to react specifically with a rabbit anti-rat beta 2m and a rabbit anti-mouse beta 2m antisera. G-200 pooled fractions from Drosophila larvae were shown to react with beta 2m-eluted and glycin-absorbed antisera, but not with beta 2m-absorbed or glycin-eluted antisera. These fractions also quantitatively inhibited the heterologous reaction between the anti-beta 2m antisera and purified human and rat beta 2m. The lack of reactivity of other rabbit antisera or normal serum with Drosophila, as well as the efficiency of absorption of anti-beta 2m reactivity by either rat or KCO% (Drosophila) cells, further supports the presence of beta 2m epitopes on Drosophila cells. Data are also presented showing that certain anti-H-2 alloantisera react with Drosophila. That this reactivity is indeed due to anti-H-2 antibodies is suggested by several lines of evidence, including the removal of cytotoxic alloantibodies and lack of reactivity by other mouse antisera and monoclonal reagents. Preliminary data suggest that the H-2-like and beta 2m-like determinants are physically associated on the cell surface of Drosophila cells. These findings have important implications on current concepts concerning the evolutionary origin and physiologic role of beta 2m and the major histocompatibility complex.

Animals↗
PubMed1981

Premenstrual periodic paralysis.

A 17-year-old girl suffered from episodes of flaccid paralysis during each menstrual cycle. No relevant changes were found in potassium concentrations in serum or erythrocytes, nor in the values of pituitary, ovarian, adrenal or thyroid hormones. Acetazolamide administration prevented the attacks.

Acetazolamide↗
PubMed1980

Detection of attograms of antigen by a high-sensitivity enzyme-linked immunoabsorbent assay (HS-ELISA) using a fluorogenic substrate.

In an attempt to increase the sensitivity of the ELISA technique three factors were examined: the use of a fluorogenic substrate (4MU-P), an increase in the antigen binding surface area, and the prolongation of the incubation time with the substrate. The use of the fluorogenic substrate and fluorometric detection method increased the sensitivity of the assay 16--39 times as compared to the colorigenic substrate (PNP-P). A 4-fold increase in the antigen binding surface area resulted in a 1000-fold increase in sensitivity, while prolonged incubation periods with the substrate at 10 degrees C yielded a further increase in sensitivity of 10--50-fold. Therefore, the present high sensitivity ELISA method (HS-ELISA) has the potential of increasing the sensitivity of the previously described method (Voller et al., 1974) by 1.6--19.5 X 10(5) times. HS-ELISA can detect as low as 3--10 attog/ml (3--10 X 10(-18) g/ml) antigen (Rb alpha M F(ab')2) or 24,000 molecules or purified mouse myeloma IgG. Our findings suggest that with simple modifications enzyme immunoassays can reach extreme levels of sensitivity.

Animals↗
PubMed1980

Evidence for the role of the maternal immune system in balancing the sex ratio in mice.

Two experiments have been conducted to verify the effect of maternal preimmunization to H-Y antigen on the secondary sex ratio in C57Bl/6 mice. In accord with the theoretical model previously proposed, it was found that extensive immunization to H-Y antigen following splenectomy resulted in a significant increase in sex ratio (males/females) without affecting litter size. Litter size was also not correlated to sex ratio. The data from both experiments suggest that splenectomy alone or restimulation to H-Y antigen (after 30 days) both act to decrease sex ratio. It is concluded that the maternal immune system plays a limited, but significant, role in maintaining the normal sex ratio in mice.

Animals↗
PubMed1980

Evidence for an H-Y crossreactive antigen in invertebrates.

A sex specific antigen which crossreacts with the mammalian H-Y antigen has been identified on the cell surface of hemocytes from the lobster (Homarus americanus) and the gonadal cells of three insect species. The hemocytes from the male lobster, the testicular cells from the male beetle (P. cornutus), and the ovarian cells from two Orthopteran species (L. maderae and D. punctata) specifically absorbed H-Y antibodies. The specificity of H-Y antibody absorptions by cells from only one sex, suggest that an ancestral H-Y-like antigen may be present in invertebrates which could be engaged in sexual (cellular) recognition events.

Animals↗
PubMed1980

Expression of H-Y antigen in the guppy (Lebistes reticulatus).

Expression of a mammalian cross-reactive H-Y antigen on the surface of cells derived from the male guppy ((Lebistes reticulatus) is demonstrated. This finding further establishes the evolutionary conservation of H-Y antigen among lower vertebrates and provides a basis for speculation on the possible evolutionary association between H-Y antigen and sex determination.

Animals↗
PubMed1980

Immunogenetics of sex determination of the polled goat.

Using the protein A rosette technique, it was found that the gene for polledness (P) in goats is associated with the presence of H-Y antigen on the cell surface of cultured fibroblasts. Two XX intersex goats (P/P) were found to be H-Y+, and one heterozygous (P/+) normal XX female was also found to express H-Y antigen at a low level. The expression of H-Y antigen by intersex goats was found to be lower than that of normal XY males. The statistical analysis suggests that animals of the same genotype and sex might differ in the density of H-Y antigen on their cell surface, which might explain the variability in primary sex determination among intersex goats. The association between the gene for sex reversal and H-Y antigen is discussed in relation to the location of the H-Y gene(s).

Animals↗
PubMed1980

Pregnancy-induced H-Y antibodies and their transmission to the foetus in rats.

Rats of DA strain produce H-Y antibodies in response to the stimulation by their male foetuses. About 52% of the rats following a single or multiple pregnancy and 45.5% of litters (female offspring) had detectable levels of H-Y antibodies in their blood serum. The presence of H-Y antibodies did not appear to be correlated with the stage of parity or the number of male foetuses the female bore. H-Y antibodies were detected in the serum of a 27 day post-partum female and her 27 day old female offspring but not in any of the male offspring. It is suggested that H-Y antibodies are transmitted to the foetus in utero and through the milk (colostrum). The possible significance of these findings in relation to the ontogenic role of H-Y antigen is discussed.

Animals↗
PubMed1980

Hepatitis B virus, sex ratio and the H-Y antigen.

The hypothesis that Hepatitis B surface Antigen (HBsAg) is cross-reactive with the male-specific H-Y antigen has been tested. In none of three separate experiments using selected anti-HBs sera, or in a fourth experiment using anti-H-Y sera, could any evidence for cross-reactivity be detected. Our results are therefore not compatible with the idea that altered sex-ratios observed among offspring of parents infected with Hepatitis B virus are related to cross-reactivity between HBsAg and a male-associated antigen.

Animals↗
PubMed1979

Pure trisomy 17p in 60% cells.

A patient with pure trisomy of the short arm of chromosome 17 in 60% of the examined cells is reported. She presented a variant chromosome 1 with partial pericentric inversion and increased centromeric heterochromatin in one chromosome 17. The cytogenetic findings are discussed. The clinical findings are compared to those found in other reported cases of partial trisomy 17 and a delineation of a pure trisomy 17p attempted.

Abnormalities, Multiple↗