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Biomedical subjects

A Abraham

Publications and source records attributed to A Abraham.

At least 55 records · Page 3Linked to original sources
PubMed1994

Induction of rotavirus-specific cytotoxic T lymphocytes by vaccinia virus recombinants expressing individual rotavirus genes.

We determined the capacity of vaccinia virus recombinants expressing individual rotavirus genes to induce virus-specific cytotoxic T lymphocytes (CTLs) in mice. Mice were orally inoculated with vaccinia virus recombinants containing genes which encode rotavirus outer capsid proteins vp4 or vp7, single-shelled virus proteins vp1, vp2, or vp6, or rotavirus nonstructural proteins NS53, NS35, NS28, or NS26/NS12. We found that (i) the greatest frequencies of virus-specific CTLs were induced by vaccinia virus recombinants expressing vp7, (ii) transport of vp7 beyond the endoplasmic reticulum was not necessary for induction of CTLs, (iii) recombinants expressing vp7 induced CTLs which reacted with different rotavirus serotypes, and (iv) CTLs were induced among both intestinal and nonintestinal lymphocytes after oral inoculation. These findings may be relevant to vaccine strategies which utilize vectors expressing individual rotavirus genes.

Administration, Oral↗
PubMed1994

FK506 enhances fibrogenesis in in vitro and in vivo models of liver fibrosis in rats.

BACKGROUND/AIMS: The immunosuppressant FK506 is undergoing clinical trials in transplantation and autoimmune diseases. FK506 modulates several cytokines and exerts hepatoprotection in acute models. This study was initiated to determine whether FK506 would be beneficial as an antifibrogenic agent. METHODS: Fibrosis was induced by carbon tetrachloride administration to rats. Half of those animals were treated with FK506. The rats were killed after 8 weeks of carbon tetrachloride treatment. The livers were evaluated by histology, Northern hybridizations, and collagen quantitation. Additionally, rat fibroblasts were incubated with and without FK506 and used for Northern hybridization analysis. RESULTS: Surprisingly, FK506 exacerbated hepatic inflammation and fibrosis. Increased hepatic collagen and higher messenger RNA levels of transforming growth factor beta 1 and collagens I, III, and IV were found in the FK506-treated group. Rat fibroblasts treated with FK506 expressed higher levels of collagens I and III, fibronectin, macrophage-colony stimulating factor, tissue inhibitor of metalloprotease, and transforming growth factor beta 1 messenger RNAs. CONCLUSIONS: These findings suggest that FK506 increases the expression of extracellular matrix genes and enhances fibrosis in the rat model. While further studies are needed to elucidate these profibrogenic mechanisms, caution is indicated for the unrestricted use of FK506 in patients subject to recurrent fibrogenic stimulation.

Animals↗
PubMed1994

Clinical and pathological description of a chronic form of bovine papular stomatitis.

This communication describes a hitherto unreported chronic form of bovine papular stomatitis in young cattle. Diagnosis was based on the clinical disease, histological findings, electron microscopical characterization of the causative virus, and virus isolation. A description of the acute form of the disease is presented for comparison.

Acute Disease↗
PubMed1994

Monocyte adhesion to fibronectin in psoriasis.

BACKGROUND: After vascular extravasation, mononuclear cells (MNC) undergo chemotaxis and adhesion to extracellular matrix proteins, resulting in their differentiation into macrophages. Although endothelial adhesion and chemotaxis are altered in psoriasis, MNC adhesion to extracellular matrix proteins has not been previously studied in the disease. Since MNC adhesion to endothelial cells is abnormally regulated in psoriasis by TGF-beta, we tested they hypothesis that in psoriasis substance P also regulates the adhesion of monocytes to the extracellular matrix protein fibronectin. METHODS: Monocytes from 16 normal controls and 11 psoriatic individuals were isolated and purified using a two-step gradient centrifugation procedure. Adhesion to fibronectin was studied by plating monocyte suspensions onto fibronectin-precoated microtiter plates. The number of adherent cells was quantified by measuring their hexosaminidase activity. RESULTS: Although statistically significant differences in the basal (unstimulated) adhesion or in the substance P-stimulated adhesion between normal control monocytes and those obtained from psoriatic individuals were not observed, a subpopulation of psoriatics was identified who responded to substance P. Furthermore, this in vitro response to substance P was correlated with the clinical status of the subpopulation which was characterized by unstable psoriasis triggered by stressful life events. CONCLUSIONS: The results of this study indicate that priming of monocytes by the extracellular matrix protein fibronectin or by elevated levels of substance P are not critical steps in the pathogenesis of stable, chronic psoriasis. Substance P may contribute to the appearance of new lesions in some individuals with unstable psoriasis.

Adult↗
PubMed1994

Parapox infection in a gazelle kid (Gazella gazella).

A captured gazelle kid (Gazella gazella) held in a mixed herd of sheep and goats in Israel developed the characteristic lesions of contagious ecthyma. Clinical diagnosis was confirmed by electron microscopy and histopathology examinations of infected tissue.

Animals↗
PubMed1994

AIDS in the tropics.

The epidemiology and clinical manifestations of AIDS in the tropics differ considerably from classic descriptions of the disease. Clinical features are reviewed in this article, with emphasis on infectious and nutritional manifestations. Management strategy in the tropics also is outlined.

AIDS-Related Opportunistic Infections↗
PubMed1993

Glycation mediated lens crystallin aggregation and cross-linking by various sugars and sugar phosphates in vitro.

Glycation of lens crystallins results in protein conformational changes, oxidation, browning and aggregation. Though glucose is the major sugar, other sugars and sugar phosphates generated as intermediates of metabolic pathways are present in the lens, albeit at low concentrations. In this study we incubated bovine lens soluble fraction with various sugars and sugar phosphates (5mM for 10 days). The reactivity was in the order trioses > tetroses > pentoses > hexoses. High molecular weight (HMW) aggregates were also formed at a comparable rate. Increased levels of fluorescence were associated with the HMW aggregates with fast reacting sugars. The phosphorylated derivatives were only slightly more reactive than their respective sugars. Interestingly, fructose-1,6-diphosphate was more reactive and cross-linked more readily than fructose-6-phosphate. Gel electrophoresis under reducing and nonreducing conditions showed formation of disulfide linked protein aggregates with slow reacting sugars such as glucose and non-disulfide covalent linked protein aggregates with fast reacting sugars such as erythrose. In contrast, if 0.1 m DTT was present in erythrose incubations (a fast reacting sugar), the HMW aggregate formation was significantly reduced. In order to show the reactivity among the slow reacting hexoses, we incubated lens proteins with 1 M hexoses for 30 days and the results showed that galactose was more reactive and showed higher cross-linking than fructose and glucose. These results thus indicate that relatively low levels of some sugars and sugar phosphates in the lens could be compensated by enhanced lens protein cross-linking and the combined effect could be rather significant with respect to cataractogenesis.

Animals↗
PubMed1993

New thiophene substituted 10-deazaaminopterins: synthesis and biological evaluation.

Analogues of 10-deazaaminopterin (10-DAM) and 4-amino-4-deoxy-10-deazapteroyl-gamma-methylene glutamic acid (MDAM) in which the benzene ring was replaced with a thiophene ring have been synthesized and evaluated for their antitumor activity. These analogues were N-([5-(2,4-diamino-6-pteridinyl)ethyl]-2-thenoyl)-L- glutamic acid (1) and N-([5-(2,4-diamino-6-pteridinyl)ethyl]-2-thenoyl)-gamma-meth ylene glutamic acid (2).

Aminopterin↗
PubMed1993

Role of the cyclic AMP response element in rat fibronectin gene expression.

Fibronectin expression is of considerable importance in normal and fibrotic liver. Plasma fibronectin levels are correlated with good prognosis in liver failure, and cellular fibronectin plays a crucial role in fibrogenesis. In this study, we observed that the H4II rat hepatoma cell line does not express fibronectin. Furthermore, a recombinant vector (pFGH) containing the promoter elements of the fibronectin gene showed no promoter function when transfected into this cell line. However, pFGH was actively expressed in L-cells and rat skin fibroblasts, cell types that express large amounts of endogenous fibronectin. To study the mechanisms regulating fibronectin expression, we evaluated the transcriptional regulatory elements of the rat fibronectin gene by mutational analysis and DNA-protein binding studies. Deletional mutation analysis showed that the sequences between positions -164 and -90 are essential for promoter activity. This region contains the consensus binding sites for CCAAT and the cyclic AMP-responsive element. Gel retardation assays demonstrated that although the binding activity to the CCAAT site at -140 was essentially the same as that in extracts from L-cells, hepatoma cells and rat livers, substantially greater amounts and different patterns of binding to the adjacent cyclic AMP-responsive element were observed in the extracts from the expressing L-cells and rat livers compared with those in the nonexpressing hepatoma cell nuclear extracts. Furthermore, mutagenesis of the cyclic AMP-responsive element site dramatically reduced promoter activity in transient transfection assays. The cyclic AMP-responsive element at position -160 appears to play an important role in the constitutive expression of the rat fibronectin gene.

Animals↗
PubMed1993

Biotin deficiency causes alterations in glycosaminoglycans and glycoproteins in rat aorta.

Biotin deficiency produced by feeding raw egg white caused decrease in the concentration of many glycosaminoglycans (GAG) in the aorta in rats fed standard laboratory diet and atherogenic diet. This decrease has been observed to be due to the increased activity of enzymes involved in the degradation of GAG and glycohydrolases which cleave the carbohydrate components of glycoproteins.

Animals↗