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Biomedical subjects

A Amar

Publications and source records attributed to A Amar.

At least 91 records · Page 5Linked to original sources
PubMed1983

Histocompatibility antigens, mixed lymphocyte reactivity and severe preeclampsia in Israel.

In the present study we have attempted to ascertain the possible existence of an association between antigens of the major histocompatibility complex (MHC) and development of severe preeclampsia (PE). HLA-A, B, C, DR antigens as well as reactivity in one-way mixed lymphocyte culture (MLC) were studied in 40 couples with severe PE, and subsequently compared to 30 normal fertile control couples. No significant differences in the frequencies of HLA antigens were detected between PE and control couples. The frequency of shared HLA-A, B and DR antigens among members of the couples was similar in both groups. The one-way MLC showed normal reactivity of both parental pairs in all combinations tested. Consequent to our data we are unable to support the suggestion that the MHC affects the susceptibility to develop severe PE.

Female↗
PubMed1983

Mixed lymphocyte reactivity nonresponsiveness in couples with multiple spontaneous abortions.

We have endeavored to ascertain the possible existence of deviant recognition of antigens controlled by the major histocompatibility complex by lymphocytes originating in couples with a history of multiple spontaneous abortions of unknown cause. Human leukocyte antigen (HLA) typing, as well as one-way mixed lymphocyte culture (MLC) tests, were performed on 33 couples with multiple spontaneous abortions and subsequently compared to 30 fertile couples with no abortion history. No significant differences in the frequency of HLA were detected between the fertile and infertile groups. The frequencies of shared HLA-A and -B antigens among members of the couples were similar in both groups. In 70% of the cases studied, the husbands revealed a depressed cellular response to their respective wives; whereas reactivity to cells from other women proved normal. However, the response of allogeneic controls to these infertile women was normal. This implies that women with multiple abortions are not poor stimulators. The specific one-way decrease in the MLC reactivity appeared to be mediated by female-derived suppressor mechanisms and may be considered as one of the causes of the interrupted development of pregnancy in vivo.

Abortion, Habitual↗
PubMed1983

HLA-D "BG" in Israel. A Japanese related allele population and family study.

An homozygous typing cell for a local HLA-D determinant"BG", defined by family study, is described. HLA-D "BG" recognizes a specificity identical to the Japanese HLA-DHO (Dw12). Two families and 102 randomly selected healthy Israeli individuals were typed for the HLA-D "BG" determinant. HLA-D "BG" showed segregation as a single determinant within families. The gene frequency for this allele was 0.045, compared to the frequency of 0.148 for DHO in Japanese. In the Israeli population "BG" is in strong association with HLA-Bw52 (joint occurrence = 7.80%) and DR2 (joint occurrence = 8.80%), resembling the data reported foar DHO (Dw12) in Japan. The frequency of this allele may partially account for the low frequency of HLA-Dw2 in the Israeli population.

Alleles↗
PubMed1983

Study of a family with Cerebrotendinous Xanthomatosis. No HLA linkage, but an informative recombination between HLA-B and Bf.

A large family with three children affected with the autosomal recessive disease of Cerebrotendinous Xanthomatosis (CTX) was studied for class I (HLA-A,B,C) and class II antigens (HLA-DR,D,SB), properdin factor B and glyoxalase. The extensive typing revealed an informative cross-over between HLA-B and Bf, indicating that Bf is located centromeric to the HLA-B locus and segregated in this family with HLA-D/DR. The parents in this family were first cousins and their parents were also first cousins. Three of their four haplotypes share B14, BfS, DR1, Dx and SB4 and may be identical by descent. The three affected children carried among them all four parental haplotypes, indicating that close linkage of the CTX locus to HLA is unlikely.

Adolescent↗
PubMed1982

HLA-DR, D recombination in a kidney transplant recipient.

Immunogenetic studies of a consanguineous family revealed discordance in the inheritance pattern of the HLA-D and HLA-DR antigens in one offspring. The findings suggest a recombination between the HLA-D and HLA-DR loci in one of the paternal chromosomes. Results on segregation of B-cell alloantigens. MLC reactivity, and glyoxalase isoenzyme determination map the DR gene between the HLA-B and D loci.

Chromosome Mapping↗
PubMed1982

HLA-D locus in Israel. Characterization of 14 local HTC's and a population study.

Fourteen homozygous typing cells identified in Israel are described. Of these typing cells two were of Ashkenazi and 11 of non-Ashkenazi origin, while the remaining HTC was from an Arab donor. Ten of the 14 HTC's characterized in this manner were offspring of consanguineous marriages; all of them were non-Ashkenari. Nine HTC's express specificities previously recognized in Caucasians, 4 HTC's represent new specificities (J1-J4), and one typing cell was found to be analogous to the Japanese Dw12 (DHO) specificity. The distribution of HLA-D specificities in 120 randomly selected Israelis representing the two main Jewish subpopulations, Ashkenazim and non-Ashkenazim, was studied with the locally defined HTC's. HLA-Dw5 and Dw10 were found to be significantly increased while Dw2 and Dw6 were significantly decreased in Israelis as compared to Caucasians.

Chromosome Mapping↗
PubMed1982

HLA-D typing in multiple sclerosis: Israelis tested with European homozygous typing cells.

The association of A3, B7, Dw2 and DR2 histocompatibility (HLA) markers with multiple sclerosis (MS) is well established among Northern Europeans and Caucasoids in the United States. We showed previously that A3 and B7 were not increased among Israelis with MS, and in a preliminary study Dw2 as well. An association of A3 and B7 is also lacking in Italians, Jordanian and Japanese MS patients. In Black American MS patients, the B7 frequency is slightly increased but Dw2 is still significantly associated with MS. For the HLA-DR antigen series DR2 is shown to have a stronger association to MS than A3 and B7. Conceivably, this antigen could be associated with MS even in populations where an association with A3 or B7 is lacking. Therefore, a study of HLA-A, B, C, DR and D antigens was carried out in Israel. No significant excess or deficiency of HLA antigens was found in MS. Possible explanations for these results are as follows: (1) the relevant HLA-D alleles in the Jewish population were not detected by the homozygous typing cells (HTCs) used, since they were derived primarily from European sources; (2) in contrast to the Caucasoid populations the genetic factor predisposing for MS is not associated with HLA alleles in the Israeli population; (3) MS is an heterogeneous disease and in Israelis, an environmental factor is sufficient to cause the disease.

Europe↗
PubMed1982

Effect of brain monoamines on the secretion of adrenocorticotrophic hormone.

The role of brain monoamines (5-HT, NA and DA) in the secretion of adrenocorticotrophic hormone (ACTH) was studied in view of contradictory reports. Plasma corticosterone levels and the rate of synthesis of corticosterone in vitro by the adrenal gland were estimated in albino rats and have been taken as the index of ACTH activity. These estimations were done in unstressed and stressed, and in untreated and treated rats. Drugs were administered intracerebroventricularly to the rats to cause selective degeneration of tryptaminergic, noradrenergic or dopaminergic neurons. The results show that plasma corticosterone levels and the rate of synthesis of corticosterone were significantly decreased after selective degeneration of tryptaminergic neurons in unstressed rats. After selective degeneration of either tryptaminergic or noradrenergic neurons, the acute increase in the plasma corticosterone levels and rate of synthesis of corticosterone in vitro by adrenal glands in stressed rats were significantly inhibited. These results have been interpreted to suggest that the central tonic control on adrenal glands may be 5-HT mediated and that during stress ACTH secretion may be both 5-HT and NA mediated. DA does not seem to have significant role in the regulation of ACTH secretion.

5,6-Dihydroxytryptamine↗
PubMed1982

Histocompatibility (HLA) antigens and multiple sclerosis in Israelis.

The association of A3, B7 and Dw2 histocompatibility (HLA) markers with multiple sclerosis (MS) is well established among North Europeans and Whites in the United States, but is apparently not universal. We previously showed that the incidence of A3, B7 and Dw2 was not higher among Israelis with MS. An association of A3 and B7 was also lacking in Italian, Jordanian and Japanese groups with MS. Recently, the HLA-DR antigen DR2 was shown to have a stronger association with MS than do A3 and B7. Conceivably, DR2 could be associated with MS even in populations where an association with A3 or B7 is lacking. Therefore, a study of DR antigens was carried out in 45 carefully defined Israeli MS patients and in matched control subjects. No significant association between MS and DR antigens was found. We conclude that the association between HLA antigens and MS is specific only to certain populations or particular regions. The implications of this observation on the role played by HLA antigens in the etiopathogenesis of MS is discussed.

HLA Antigens↗
PubMed1981

Immobilization stress in rats: effect on rectal temperature and possible role of brain monoamines in hypothermia.

Immobilization of albino rats for 2 h showed ambient temperature-dependent changes in rectal temperature, hypothermia at temperatures below 30 degrees C, and hyperthermia at 35 degrees C and above. Adrenalectomized (Adre) rats showed more hypothermia compared to sham operated controls at 25 +/- 2 degrees C. The increased hypothermia in adrenalectomized rats was reversed by 10 mg/kg IP or 100 microgram/rat ICV of hydrocortisone. Groups of rats pretreated with desmethylimipramine (DMI, 25 mg/kg IP) and 6-hydroxydopamine (6-HD, 100 microgram/rat ICV) or methyl ester of parachlorophenylalanine (ME-PCPA, 100 microgram/rat ICV for 3 days) or 5,6-dihydroxytryptamine (DHT, 75 microgram/rat ICV) showed significantly less hypothermia at the end of 2 h of immobilization. Applying analysis of variance test, the hypothermia in Adre, ME-PCPA and DHT groups, was found to be not significantly different from their respective control groups between 0 and 45 min of immobilization but was significantly different between 45 to 120 min of immobilization. DMI-6-HD group however, showed significant difference between 0--45 min only and not between 45--120 min of immobilization. The results suggest that the early phase of immobilization induced hypothermia between 0--45 min is dopamine and the late phase of hypothermia between 45--120 min is 5-hydroxytryptamine mediated.

5,6-Dihydroxytryptamine↗
PubMed1981

Genetics of insulin dependent diabetes mellitus in Israel: population and family study.

The association between insulin dependent diabetes mellitus (IDDM) and the HLA system was studied in two groups of Jewish patients: 50 Ashkenazim and 42 non-Ashkenazim. The pattern of association of HLA-A and B locus antigens was somewhat different from that observed in European Caucasian patients. HLA-B8 had a higher frequency; B15 and Cw3 were rare in the population studied and were less frequent in IDDM patients than in controls. On the other hand, the frequency of A26, B18, and Bw38 was increased in Ashkenazi patients, but not in non-Ashkenazim, who in turn showed an increase for Bw51. Although the association between IDDM and HLA-A and B locus antigens shows a marked variability in different populations, the association with HLA-DR3 and DR4 is constant feature. There was a typical excess of DR3/DR4 heterozygotes in both patient groups. This heterozygote type carries the highest relative risk, followed by DR4/DR4 homozygotes. These data can well be interpreted by a model of two different HLA-linked susceptibility genes, one associated with DR3 and the other one with DR4, that interact so that different genotypes are associated with different levels of penetrance. This model received further support from studies in 15 multiple case families where there is an excess of affected sib pairs sharing two DR antigens.

Adolescent↗
PubMed1981

Histocompatibility determinants in Israeli Jewish patients with coeliac disease: population and family study.

The association between HLA and coeliac disease (CD) was studied in the Jewish population of Israel. A total of 112 patients were typed for HLA-A,B,C antigens, including 67 patients whose families were typed in order to deduce the genotypes. Forty-seven patients were typed for HLA-DR antigens. The HLA-A,B,C data show a pattern of association, which is similar to that found in European CD patients: HLA-B8 is increased, although to a lower degree; a suggestive, insignificant increase for Aw30, B13 and Cw6 and a decrease of Bw35 were noted. The DR antigens DR3 and DR7 are associated with CD in the Jewish population. An excess of DR3/DR7 heterozygotes was noted. The data from family and population studies support a model in which two different HLA-DR associated genes are interacting.

Celiac Disease↗
PubMed1979

Is the vertical disposition of Mycoplasma membrane proteins affected by membrane fluidity?

The influence of the physical state of the membrane lipid matrix on the vertical disposition of membrane proteins was studied with Acholeplasma laidlawii. Changes in membrane fluidity were brought about by altering the fatty acid composition of membrane lipids, by changing the growth temperature, by aging of cultures and by inducing changes in the membrane lipid-to-protein ratio through treatment with chloramphenicol. The lactoperoxidase-mediated iodination technique was used to label membrane proteins exposed to the aqueous surroundings. The degree of exposure of the iodine-binding sites of membrane proteins on the external surface of intact cells was found to undergo significant changes on varying growth conditions, but the changes could not be consistently correlated with changes in membrane fluidity, nor were they discernible on iodination of isolated membranes.

Acetates↗
PubMed1979

Comparison of radioimmunoassay and counterimmunoelectrophoresis for the detection of hepatitis B surface antigen carriers in a high-prevalence region.

Solid-phase radioimmunoassay (RIA) and counterimmunoelectrophoresis (CIE) were compared for the detection of hepatitis B surface antigen (HBsAg) carriers among blood donors in Jerusalem, which is in a region characterized by a high prevalence of HBsAg and a predominance of the ayw subtype. RIA detected 84% more HBsAg carriers than CIE, with the resultant exclusion of 1.8 times as many potentially infective donors. The results provide additional information concerning the specific increases in donor-carrier detection that are associated with the introduction of highly sensitive HBsAg tests in different geographic and epidemiologic circumstances.

Blood Donors↗