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Biomedical subjects

A Ma

Publications and source records attributed to A Ma.

At least 91 records · Page 5Linked to original sources

Anti-clonotypic autoantibodies in pregnancy.

Idiotypic T-cell receptors for antigen have been identified in previous studies by use of anti-clonotypic monoclonal antibodies. To determine whether anti-receptor autoantibodies play a role in immune regulation, we have used normal pregnancy as a model. T-cell clones were generated from the peripheral blood of a primiparous woman by priming her lymphocytes to stimulating cells from her husband. As a control, T cells primed to lymphocytes from HLA different controls were used. Purified IgG was prepared from this woman's serum and tested for its reactivity with cell surface antigens expressed by autologous T-cell clones. We have identified one anti-HLA-DR reactive clone specific for the immunizing HLA haplotype of the child that reacted with autologous F(ab')2 in immunofluorescence studies. When tested in functional studies, the F(ab')2 blocked the capacity of the clone to lyse specific target cells, while triggering clonal proliferation in the absence of stimulating cells. The determinant(s) recognized by autoantibodies in the F(ab')2 preparation comodulate with the T3 antigen present on the surface of the cells. These data suggest that sera obtained during pregnancy contain autoantibodies which behave similarly to heterologous anti-clonotypic antibodies. Such anti-T-cell receptor antibodies may play a role in maternal tolerance to the fetus.

Autoantibodies↗

Perturbation of the immune network in herpes gestationis.

We have studied the development of anti-idiotypic antibodies to HLA and of autoantibodies reacting with alloactivated T lymphoblasts in a woman with herpes gestationis (HG). This primigravida developed an elevated titer of anti-HLA antibodies, (Ab1), in association with a low titer and late appearance of anti-anti-HLA antibodies (Ab2). At delivery she developed only minimal levels of antibodies reacting with autologous T lymphoblasts (T1), sensitized against the immunizing HLA antigens of the child. Her serum reacted, however, with T lymphoblasts, primed in AMLC against autologous T blasts alloactivated in vitro against her husband (T2). Because healthy gravidae do not show such antibodies, it appears that they are peculiar to and may represent a perturbation of the idiotypic network in regard to the immune

Autoantibodies↗

Human papillomavirus infection of the esophagus. A clinicopathologic study with demonstration of papillomavirus antigen by the immunoperoxidase technique.

Papillomaviruses are known to be oncogenic in animals. In humans they are associated with benign squamous tumors (verruca, condylomata acuminata, and papillomas) in a variety of body sites. Human papillomavirus (HPV) infection of the esophagus, however, has not previously been documented. Recent reports of condylomatous changes in esophageal epithelium adjacent to esophageal carcinoma and the sporadic descriptions of esophageal papillomas in the literature for many years, lend credence to the assumption that HPV may affect the squamous mucous membrane of the esophagus. In the current study 75 cases, including 2 papillomas and 73 focal epithelial hyperplasia of the esophagus, were examined for histologic evidence of HPV infection as characterized by the presence of koilocytosis, giant and multinucleated cells, dyskeratosis, hyperkeratosis, acanthosis, papillomatosis, and anisonucleosis. Thirteen of the cases--the 2 papillomas and 11 of the focal epithelial hyperplasias--contained distinctive histologic evidence of HPV infection. The presence of HPV antigens was demonstrated by immunoperoxidase (IMPO) in the 4 of the 13 cases (31%). In the remaining cases the IMPO was equivocal in two and negative in seven.

Adult↗

Defective thermoregulatory thermogenesis in monosodium glutamate-induced obesity in mice.

We have studied thermoregulatory thermogenesis in mice rendered obese by neonatal administration of monosodium glutamate (MSG) and in saline treated controls. At 12 weeks of age MSG-treated mice maintained on a chow diet and housed at 24 degrees C, exhibited hypertrophy of brown adipose tissue (BAT) compared to controls (65% increase in wet weight and lipid content, no difference in DNA content). Acute cold exposure (4 degrees C for two hours) resulted in a significantly greater fall in core temperature in MSG-treated than control mice. After cold exposure to 4 degrees C for six hours, control animals mobilized BAT lipid whereas MSG-treated animals did not. Both groups showed comparable increments in oxygen consumption in response to exogenous norepinephrine. The above changes were qualitatively the same for both male and female animals. The following conclusions were reached: (1) MSG-treated mice have defective cold induced thermogenesis, indirect evidence suggests this results from impaired activation of thermogenic mechanisms in BAT; (2) the defect responsible for this lies extrinsic to BAT; and (3) the quantitative significance of defective thermoregulatory thermogenesis for the development of obesity in these mice is uncertain.

Adipose Tissue↗

Cafeteria feeding promotes diet-induced thermogenesis in monosodium glutamate-treated mice.

We studied diet-induced thermogenesis (DIT) in cafeteria fed monosodium glutamate (MSG) and saline-treated mice. From 12 weeks of age MSG and saline-treated mice were fed a diet of either standard chow or a cafeteria diet of standard chow supplemented with chocolate or biscuits on alternate days for six weeks. There was a significant weight gain in cafeteria fed MSG-treated mice but not in cafeteria fed saline-treated mice. In cafeteria fed MSG-treated mice there was a significant increase in resting oxygen consumption. The response to exogenous norepinephrine was significantly increased in cafeteria fed saline-treated mice. The level of specific tritiated guanosine 5'-diphosphate binding to isolated mitochondrial fractions was significantly increased in both cafeteria fed MSG and saline-treated mice. It is concluded that (1) cafeteria feeding is capable of promoting DIT, within brown adipose tissue (BAT), in MSG-treated mice and (2) the mechanisms for the induction of thermoregulatory thermogenesis (TRT) and DIT are distinct since cold-induced TRT has previously been shown to be defective in MSG-treated mice.

Adipose Tissue, Brown↗

Distinctive acral erythema occurring during therapy for severe myelogenous leukemia.

A distinctive acral erythema developed in four patients with myelogenous leukemia, subsequent to blood transfusions and intensive chemotherapy with cytarabine. The clinical and histopathologic features of the eruption were suggestive of a drug-induced toxic eruption. To our knowledge, only one previous similar case has been reported in the literature. For patients in whom this self-limited condition develops, reassurance should serve as the mainstay of therapy.

Adult↗

Measurement of human erythroid burst-promoting activity by a specific cell culture assay.

A two-stage cell culture assay specific for human erythroid burst-promoting activity (BPA) is described. Human peripheral blood mononuclear cells were cultured in suspension with or without a BPA test sample for two days, then transferred to methylcellulose medium with added erythropoietin (EPO) and incubated for ten more days, and finally BFU-E-derived colonies were scored. An increase in number of colonies due to the presence of BPA was observed that was proportional to the concentration of BPA in the test sample. This response was linear with respect to number of cells plated between 2 and 5 X 10(5)/ml. The system was standardized with a partially purified human urinary BPA preparation. Dose responses to urinary protein preparations, plasma, and serum were parallel. The assay system was found to be nonresponsive to highly purified EPO and to bacterial endotoxin. It was determined that BPA action was confined to the suspension culture stage of the assay, while EPO presence was an absolute requirement during methylcellulose culture. In the two-stage assay optimal amounts of BPA caused up to 358% increases of BFU-E-derived colonies; the same amounts of BPA added to conventional methylcellulose cultures caused only up to 54% increases over the number of colonies obtained with EPO alone. Plasma and serum BPA levels of hematologically normal and abnormal individuals showed no correlation with EPO levels and hemoglobin (Hb) concentrations. This seems to rule out the possibility that BPA elaboration is regulated by oxygen availability or the amount of EPO circulating in an organism.

Anemia, Aplastic↗

A clinical trial of prostaglandin E2 to increase erythropoiesis in anemia of end stage renal disease. A preliminary report.

Prostaglandin E2 is known to stimulate erythropoiesis by different mechanisms. A clinical trial of prostaglandin E2 to stimulate erythropoiesis in four patients with anemia of end stage renal disease resulted in an increment in peripheral blood Burst Forming Units-Erythroid (BFU-E). This increase in erythroid progenitors returned to baseline with cessation of therapy. A significant increase in serum erythropoietin (EPO) activity was demonstrated in one patient and was noticeable in another. Side effects mainly consisted of local pain at the site of the infusion and vomiting.

Adolescent↗

Isolation of rat hepatocyte plasma membranes. I. Presence of the three major domains.

A rat liver plasma membrane preparation was isolated and characterized both biochemically and morphologically. The isolation procedure was rapid, simple and effective in producing a membrane fraction with the following biochemical characteristics: approximately 40-fold enrichment in three plasma membrane markers, 5'-nucleotidase, alkaline phosphodiesterase I (both putative bile canalicular membrane enzymes), and the asialo-glycoprotein (ASGP) receptor (a membrane glycoprotein present along the sinusoidal front of hepatocytes); a yield of each of these plasma membrane markers that averaged approximately 16%; and minimal contamination by lysosomes, nuclei, and mitochondria, but persistent contamination by elements of the endoplasmic reticulum. Morphological analysis of the preparation revealed that all three major domains of the hepatocyte plasma membrane (sinusoidal, lateral, and bile canalicular) were present in substantial amounts. The identification of sinusoidal membrane was further confirmed when ASGP binding sites were localized predominantly to this membrane in the isolated PM using electron microscope autoradiography. By morphometry, the sinusoidal front membrane accounted for 47% of the total membrane in the preparation, whereas the lateral surface and bile canalicular membrane accounted for 6.8% and 23% respectively. This is the first report of such a large fraction of sinusoidal membrane in a liver plasma membrane preparation.

Animals↗

Isolation of rat hepatocyte plasma membranes. II. Identification of membrane-associated cytoskeletal proteins.

Rat liver plasma membranes were isolated as presented in the preceding paper (Hubbard, A. L., D. A. Wall, and A. Ma., 1983, J. Cell Biol., 96: 217-229) and found to contain many filaments associated both with desmosomes along the lateral surface and with the cytoplasmic aspects of membranes comprising each of the three domains (lateral [LS], bile canalicular [BC] and sinusoidal [SF] ). Exposure of the plasma membranes to alkaline media (up to pH 11) resulted in loss of recognizable filaments without loss of domain morphology or membrane enzyme activities. Electrophoretic analysis of solubilized components from control and alkaline-extracted plasma membranes revealed that three major polypeptides present at 43, 52, and 56 kdaltons in the control had been released by alkaline treatment (pH 11) and could be quantitatively recovered in the supernate. The 43-kdalton component was identified as cytoplasmic actin by comparison of its tryptic 125I-peptide map to those of muscle (alpha) and brush border (beta, gamma) actins. The 52- and 56-kdalton polypeptides were identified as tonofilament components by their solubility properties and their ability to reassemble into 9.5-nm filaments from monomers present in an alkaline extract.

Actins↗

The relationship between human spleen and blood erythroid burstforming units (BFU-E).

The influence of splenectomy on erythroid burst colony formation by peripheral blood mononuclear cells from 10 patients (four with hereditary spherocytosis, two with beta-thalassaemia major, two with Hodgkin's disease and two with idiopathic thrombocytopenic purpura) was studied. In every instance splenectomy was followed by a lowering of blood BFU-E. The post-splenectomy levels ranged from 0 to 30% of the preoperative levels. Mononuclear cells from the spleens of eight patients were cultured and found to contain numerous BFU-E. The total quantity of BFU-E in the whole blood and in the spleen of the patients was generally of the same order of magnitude. The number of splenic BFU-E did not correlate with spleen size. Splenic BFU-E differed from peripheral blood BFU-E in that they were more sensitive to erythropoietin (Ep) and in that they failed to respond to burst promoting activity (BPA) produced by preincubating the spleen mononuclear cells with phytohaemagglutinin M (PHA). In contrast, media conditioned by PHA-treated spleen cells contained BPA active on peripheral blood BFU-E from normal individuals. These data suggest that the spleen may have an influence on the numbers and functional properties of BFU-E.

Adolescent↗

Response of generalized granuloma annulare to high-dose niacinamide.

A patient with generalized granuloma annulare experienced resolution of her lesions after six months of treatment with 1,500 mg/day of niacinamide. Niacinamide seems to be a reasonably safe drug that, even at relatively high doses, is associated with a low incidence of side effects. The participation of a delayed hypersensitivity reaction in the pathogenesis of granuloma annulare and possible mechanisms involving niacinamide in this type of reaction are discussed.

Female↗

Glycosylated plasma protein: a simple method for the elimination of interference by glucose in its estimation.

Interference by glucose in the colorimetric estimation of glycosylated plasma protein was effectively eliminated by the precipitation of the proteins with trichloroacetic acid. The procedure was rapid and the recovery of protein quantitative. Results were highly reproducible. Preliminary clinical data obtained using the modified procedure showed rapid reflection by glycosylated plasma protein of the short-term control of glucose levels in diabetics when glycosylated haemoglobin values failed to indicate changes.

Blood Glucose↗