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A Barat

Publications and source records attributed to A Barat.

At least 55 records · Page 3Linked to original sources
PubMed1990

Co-existence of hepatocyte ground-glass inclusions from several causes.

Two patients with two and three types respectively of ground-glass hepatocyte inclusions are described. Both were hepatitis B surface antigen (HBsAG) positive and received cyanamide for alcohol aversion therapy. In addition, one of them had taken benzodiazepines and barbiturates. In one patient, cyanamide and HBsAg inclusions co-existed in the same hepatocytes.

Adult↗
PubMed1990

Interaction of asymmetric and globular acetylcholinesterase species with glycosaminoglycans.

Chicken muscle and retina, and rat muscle asymmetric acetylcholinesterase (AChE) species were bound to immobilized heparin at 0.4 M NaCl. Binding efficiency was between 50 and 80% for crude fraction I A-forms (AI; muscle), and nearly 100% for fraction II A-forms (AII; muscle and retina). Antibody-affinity-purified AI-forms (chicken) were, however, quantitatively bound to heparin-agarose gels, whereas diisopropylfluorophosphate-inactivated high-salt extracts partially prevented the binding of both AI and AII AChE forms, thus suggesting the presence in crude AI extracts of heparin-like molecules interfering with the tail-heparin interaction. All bound A-forms were progressively displaced from the heparin-agarose columns by increasing salt concentrations, with maximal release at about 0.6 M. They were also efficiently eluted by heparin solutions (1 mg/ml), other glycosaminoglycans being much less effective. Chicken globular AChE forms (G-forms, both low-salt-soluble and detergent-soluble) also bound to immobilized heparin in the absence of salt. Stepwise elution with increasing NaCl concentrations showed maximal release of G-forms at 0.15 M, all globular forms being totally displaced from the column at 0.4 M NaCl. Heparin (1 mg/ml) had the same eluting capacity as 0.4 M NaCl, whereas other glycosaminoglycans were only marginally effective. We conclude that the molecular forms of AChE in these vertebrate species interact with heparin, at salt concentrations that are characteristic for asymmetric and globular forms. Within the A and G molecular form groups, no differences were found in the behavior of the different fractions or subtypes, provided that the enzyme samples were free of interfering molecules.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1990

Detection and characterization of circulating and glomerular immune complexes in experimental IgA nephropathy.

The different models of experimental IgA nephropathy described so far have provided insight into pathogenesis; however, the evidence for a role of IgA immune complexes (IC) has only been gained in passive systems. In an active model of IgA nephropathy, induced in mice by repeated injections of dextran, some of the mechanisms that could explain the formation of glomerular IgA deposits are studied in this report. Serum total IgA and anti-dextran IgA antibody levels increased significantly over the period of immunization. Only 13-30% of mice had total and/or specific IgA IC, determined by Raji cell and PEG assay in ELISA. Analytical ultracentrifugation showed that IgA IC were of small (7-13 S) or intermediate (13-17 S) size. There was a close correlation between total serum IgA levels and the presence of IC-containing IgA anti-dextran antibodies, with the existence of IgA in the mesangium. The percentage of animals (n = 76) with IgA mesangial deposits increased over the immunization period (88% at 10 weeks). Forty-three per cent of mice had polymeric IgA in the mesangium; by contrast, only 12% had dextran deposits. On the whole, these data suggest that in the dextran-induced IgA nephropathy, the glomerular IgA could be the result of circulating IgA complexes and/or IgA polymers deposition.

Animals↗
PubMed1989

Compartmentalization of acetylcholinesterase in the chick retina.

Using selective inhibitor treatments, we have studied the distribution of asymmetric (A) and globular (G) forms of acetylcholinesterase (AChE) in the extra- and intracellular compartments of chick retina, a specialized region of chick central nervous system (CNS). Our results show that the chick retinal collagen-tailed AChE (an example of class II asymmetric molecular forms) is essentially an extracellular form of the enzyme; this is the first demonstration of the extracellular localization of asymmetric AChE in the vertebrate CNS. The active site of most of the hydrophobic, membrane-bound G4-form is also exposed to the external environment. In turn, the smaller molecular weight G-forms (G2 and G1) are localized within the cells, where they may represent intermediate components in the assembly or degradation of the more complex enzymatic molecular species. Histoenzymatic ultrastructural techniques show internal AChE in amacrine as well as in ganglion cell bodies, and external enzyme, specifically associated with synapses and axons, in the inner plexiform layer. The probable cooperation of the extracellular A12-forms and the membrane-bound G species (mainly G4) of the enzyme to the hydrolysis of acetylcholine (ACh) released into the external compartment is suggested and discussed.

Acetylcholinesterase↗
PubMed1989

GABAergic modulation of acetylcholine release in cholinergic synaptosomes from Torpedo marmorata electric organ.

GABAA- and GABAB-receptor-specific agonists inhibit the depolarization-evoked release of acetylcholine in cholinergic synaptosomes from Torpedo electric organ. Over 60% of the release is inhibited by a 10(-4) M concentration of GABA itself. IC50s for muscimol and baclofen are 1.3 x 10(-4) and 2.2 x 10(-6) M, respectively. The effect of muscimol is totally blocked by the direct antagonist bicuculline methiodide, and also by the allosteric antagonists methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate, picrotoxinin and tert-butylbicyclo-orthobenzoate; the effect of baclofen is blocked by delta-aminovalerate. Furthermore, the inhibitory action of muscimol on acetylcholine release is substantially enhanced by flunitrazepam and pentobarbital. These results suggest the existence of typical GABAA and GABAB receptors in the presynaptic nerve terminals of the Torpedo electric organ regulating the liberation of acetylcholine and therefore the discharge of the electroplaques.

Acetylcholine↗
PubMed1987

Metastatic pure choriocarcinoma of the testis in an elderly man.

The case described of pure choriocarcinoma of the testis is rare because of the histological type and patient age at presentation. A 63-year-old man had a 160 gm. tumor, with a necrotic, hemorrhagic appearance and sparse bright areas that consisted exclusively of syncytial and cytotrophoblastic cells. Immunocytochemical analysis revealed strong staining for human chorionic gonadotropin in the syncytiotrophoblastic cells. The specimen was moderately positive for keratin and negative for alpha-fetoprotein.

Choriocarcinoma↗
PubMed1986

Heparin and the solubilization of asymmetric acetylcholinesterase.

Heparin solubilizes asymmetric acetylcholinesterase, from chick skeletal muscle and retina, as a 24 S complex which is quantitatively converted to conventional asymmetric molecular forms of the enzyme (A12 and A8, either class I or class II) upon exposure to high salt. The simultaneous presence of salt and heparin in the homogenization medium selectively prevents, however, the release of class II A-forms in both muscle and retina. Heparin may generally act by displacing native proteoglycans involved in the attachment of the enzyme tail to the extracellular matrix, or its neural equivalent, being in turn removed by salt to yield typical asymmetric enzyme forms. Heparin would also appear to displace some other molecules specifically involved in the EDTA-sensitive attachment of class II tailed forms, this effect being antagonized by salt.

Acetylcholinesterase↗
PubMed1986

[Merkel's tumor].

Explore the source record for details and available documents.

Adenocarcinoma↗
PubMed1984

Phenytoin in IgA nephropathy: a long-term controlled trial.

The final report of a long-term nonrandomized controlled trial of phenytoin therapy in patients with IgA nephropathy is presented. The mean time period of follow-up was 17 months (range 6-48) in the treated group (41 patients) and 14 months (range 6-36) in the nontreated group (32 patients). Both groups were comparable in age, sex, onset of the nephropathy, blood pressure and renal function. The number of episodes per year of macroscopic hematuria decreased in both groups, but was significantly lower at each time period in the treated group than in the control one. The diminution of microhematuria only occurred in the treated group. 1 patient in each group developed advanced renal failure. The mean serum IgA concentration diminished significantly in the treated group, as early as 6 months, but not in the nontreated group. There was a certain association between the presence of the HLAA2 and BW 35 antigens and the lowering of serum IgA. A normalization of the high serum levels of polymeric IgA occurred in the treated patients. A marked diminution of the Raji IgA immune complexes, well correlated with hematuria, was only observed in the treated group. However, despite the diminution of the serum IgA levels, the disappearance of the potential pathogenic IgA immune complexes and the hematuria in a number of treated patients, a progression in the percentage of global or focal glomerular sclerosis and/or vasculointerstitial lesions was seen in some of them. It is concluded that phenytoin decreases the clinical activity and corrects some of the immunological alterations of a certain number of patients with IgA nephropathy but has no valuable effects on the renal lesions. The overall results of this trial do not suggest the employment of this drug in patients with IgA nephropathy and normal renal function. Our data also suggest that a nonimmunological mechanism may be of importance in the progression of chronic renal damage in this disease.

Adolescent↗
PubMed1983

Fate of collagen-tailed acetylcholinesterase upon extraction of chick retina with salt-detergent solutions in the absence of EDTA.

In chick retina, the tailed 20S molecular form of acetylcholinesterase (A12) is slowly degraded to globular forms after homogenization of the tissue in a buffer-salt-detergent solution, in the absence of EDTA. This process can be stopped by the addition of EDTA to the homogenate, prior to high speed centrifugation; however, longer delays in adding EDTA lead to lower recoveries of tailed enzyme. The rate of degradation of A12 is considerably enhanced by high speed centrifugation of this EDTA-less homogenate prior to addition of EDTA.

Acetylcholinesterase↗
PubMed1982

Rat serum sickness: possible role of inflammatory mediators allowing deposition of immune complexes in the glomerular basement membrane.

Serum sickness was induced in rats by a modification of previously described methods avoiding i.v. administration of the antigen. All the animals developed a progressive disease characterized by an initial pattern of deposition of IC in the mesangium followed by the appearance of GBM deposits. This change in the deposition of IC was associated with the onset of massive proteinuria and a fall in the titre of precipitating antibodies. Simultaneously, specific desensitization of platelets for a rat PAF could be demonstrated and platelet aggregates were seen in the glomeruli. The presence of homocytotropic IgGa anti-ovalbumin antibodies in rat sera during the induction of the disease was demonstrated by 2 hr PCA. Accordingly, this antibody together with the antigen ovalbumin induced the release of histamine from peritoneal mast cells, suggesting that a similar mechanism might occur in vivo during the induction of the disease. Rat PAF and beta glucuronidase could be obtained from peritoneal macrophages under similar conditions to those required for the release of histamine. The data support a role for inflammatory mediators in the increase in vascular permeability needed for the deposition of IC in the GBM and provide evidence for a new role of macrophages and PMNs in glomerular pathology in contributing to an increase in permeability of GBM.

Animals↗