Search PubMed⌕ Search

Biomedical subjects

J Barbosa

Publications and source records attributed to J Barbosa.

At least 145 records · Page 8Linked to original sources
PubMed1981

Is diabetic microangiopathy genetically heterogeneous? HLA and diabetic nephropathy.

We have studied the histocompatibility (HLA) antigens A and B in 99 insulin dependent diabetics (IDDN) with terminal uremia due to diabetic nephropathy and in 96 insulin dependent diabetic patients (IDD) without clinically detectable kidney disease. The two groups were matched for duration of disease and other clinical features. The frequencies of the HLA antigens B8, B15, B18 and B8/B15 were significantly increased in both groups and B7 and B12 were decreased. There were no significant differences between the two groups. These results contrast with previously described similar studies of HLA and diabetic proliferative retinopathy. In these studies B7 was significantly less common in patients with proliferative retinopathy as compared with patients without proliferative retinopathy and B15 was more common in a subset of patients with proliferative retinopathy. The differences between the two studies may reflect sample bias or a genetic difference between the two types of diabetic microangiopathy.

Adult↗
PubMed1981

Gene for monoamine oxidase type A assigned to the human X chromosome.

Inherited variations in monoamine oxidase (MAO) activity are thought to affect human behavior and expression of disease. The present study has established the chromosomal location of one of the structural genes coding for this enzyme. Mapping was carried out by somatic cell hybridization between normal human skin fibroblasts and mouse neuroblastoma cells. Selective media for growth of cells with or without hypoxanthine phosphoribosyltransferase (HPRT) activity were used to obtain hybrid lines which had retained or lost the human X chromosome, respectively. Cytogenetic techniques, isozyme analysis, and limited proteolysis and peptide mapping of [3H]pargyline-labeled MAO were used to characterize hybrid lines. With one exception, only lines containing the human X chromosome and human forms of two X-linked enzymes (phosphoglycerate kinase and glucose-6-phosphate dehydrogenase) expressed the human form of the flavin polypeptide of type A MAO. The exceptional hybrid line contained a putative translocation of part of the human X chromosome, since it expressed human forms of both MAO and phosphoglycerate kinase but neither the human form of glucose-6-phosphate dehydrogenase nor HPRT activity. This evidence indicates that the structural gene for the flavin polypeptide of MAO-A is on the human X chromosome. This represents the first chromosomal assignment of a human gene coding for an enzyme of neurotransmitter metabolism. This information will help to elucidate the structure of MAO and modes of its inheritance in the human population.

Animals↗
PubMed1980

Histocompatibility antigen frequencies in diabetic retinopathy.

We studied the histocompatibility antigens A and B in 300 insulin-dependent diabetics: 200 had proliferative retinopathy and 100 did not. The two groups were matched for known duration of diabetes and other clinical features. In both groups the frequencies of HLA-B8, HLA-B18, and HLA-B8/HLA-B15 were significantly higher, and those of HLA-B7 and HLA-B12 were significantly lower than in healthy controls. The patients with proliferative retinopathy were significantly less often positive for HLA-B7 (X2 = 10.0; Pc < .03) than patients with nonproliferative retinopathy. When both groups were stratified for age at diagnosis, there were additional differences. HLA-B15 was significantly more frequent in the proliferative retinopathy group with age at diagnosis between 15 and 40 years (nonproliferative retinopathy = 16.4%; proliferative retinopathy = 39.4%; X2 = 7.89, Pc < .03; relative risk = 3.32) and HLA-B7 significantly less frequent (nonproliferative retinopathy = 23.6%; proliferative retinopathy = 5.6%; X2 = 8.0, Pc < .03; relative risk = 0.19). These differences in histocompatibility frequencies between patients with and without proliferative retinopathy indicate a genetic contribution to diabetic retinopathy.

Adolescent↗
PubMed1980

Linkage analysis between the major histocompatibility system and insulin-dependent diabetes in families with patients in two consecutive generations.

We have histocompatibility (HLA) genotyped 28 families with insulin-dependent diabetics in two or more consecutive generations, usually parent and child. This strategy of ascertainment was used to maximize the likelihood of obtaining a homogeneous type of disease within a family, and an autosomal dominant mode of inheritance. 76 diabetics and 169 nondiabetics were studied in these families. The frequencies of the antigens Dw3 and Dw4, and the genotype Dw3/Dw4 among the diabetics are 59, 68, and 30%, respectively, as compared with 15, 12, and 2% in normal controls, and 43, 41, and 10% in the nondiabetic relatives of the diabetics. Dw2 is present in only one diabetic (4%), as compared with 18% in normal controls and 17% in nondiabetic relatives.HLA haplotype concordance was analyzed for sib pairs in relation to the haplotype shared by the affected parent/child pair, and for the diabetic sib pairs within each sibship. The results failed to reveal deviations in the expected HLA haplotype assortment. Assuming an autosomal dominant mode and several penetrance levels, linkage analysis between the HLA and diabetes was performed. The total lod score is 0.37 for a recombination fraction of 0.29 at 50% penetrance. Although the linkage and concordance analysis results are inconclusive, they seem to be different from those reported by us for families with normal parents and two or more diabetic sibs. Because ascertainment biases may have influenced these results in an unquantifiable manner, it is not certain whether the two types of families are genetically different. However, the marked difference in the lod scores for the 50% penetrant autosomal recessive model between the two types of families is compatible with a genetic dissimilarity between them. The high frequency of the Dw3 and Dw4 antigens, the Dw3/Dw4 genotype, and the decreased frequency of Dw2, however, indicate the existence of two or more important diabetic genetic factors associated with the D region of the HLA in these families.

Diabetes Mellitus, Type 1↗
PubMed1979

On the genetic heterogeneity of juvenile hyperglycemia.

We have briefly discussed immunogenetic studies of families with hyperglycemia which suggest the existence of at least four types of the disease: a) juvenile, insulin-dependent, ketosis prone diabetes determined by an autosomal recessive gene with 50% penetrance and in linkage with the HLA; b) juvenile, insulin-dependent, ketosis prone diabetes probably determined by an autosomal dominant gene; c) unidentified types of juvenile, insulin-dependent diabetes whose pathogenesis may be related to the HLA associations reported; and d) maturity onset type of hyperglycemia in the young, probably determined by an autosomal dominant gene. There are probably other forms of juvenile hyperglycemia. Some may depend on genes unrelated to the HLA, others may be mostly or totally environmental, rather than genetic.

Adolescent↗
PubMed1979

HLA-Dw antigens in unrelated juvenile, insulin-dependent diabetics.

Forty-one unrelated juvenile, insulin-dependent diabetics have been HLA tissue typed for A, B and Dw anitgens and compared with a normal control population. We have found statistically significant increases in the frequencies of B8, B18, and Dw3, and significant decrements in the frequencies of B7, B12 and Dw2. The log-linear modeling technique was used to study the association of JIDD with Dw3 and B8 antigens. We confirmed that the B8 excess seen in diabetics is secondary to the excess of Dw3. The decrements of B7, B12 and Dw2 could reflect an association of these antigens with a protective factor for the disease, or could be due to an artifact. The latter possibility was excluded for B7 and Dw2 by adjusting for the excess antigen frequencies. These findings suggest that the associations between the HLA and diabetes are compatible with the existence of genes which are concerned with the pathogenesis of the disease and are closely associated with the D locus of the major histocompatibility system.

Adolescent↗
PubMed1979

Effects of (Bu2)-cAMP and clomiphene on serum concentrations of several proteins and hormones in gonadectomized monkeys.

Sixteen mumol kg-1 of dibutyryl cyclic adenosine 3',5'-monophosphate [(Bu)2cAMP] given intramuscularly to gonadectomized green monkeys (Cercopithecus aetheops sabeus) for two-week periods, produced a significant elevation in the serum concentrations of thyroxine-binding globulin (TBG), fibrinogen, and haptoglobin. No changes were noted in cortisol-binding golbulin (CBG), cortisol, thyroxine, transferrin, total proteins, and albumin. Clomiphene citrate (12.5 mg orally) given concomitantly with (Bu)2cAMP blocked partially the (Bu)2cAMP-induced fibrinogen increment, but not the change in TBG concentration.

Administration, Oral↗