Biomedical subjects

A Barat

Publications and source records attributed to A Barat.

At least 19 recordsLinked to original sources

PubMed2002

[Benign prostatic hyperplasia: biological significance of lymphohistiocytic infiltration of the adenoma].

The presence of mononuclear cells infiltrating the prostate adenoma is a morphological observation well established in the literature. However, its biological meaning is a subject of controversy. It has been postulated that it may represent a local immunological reaction contributing to the pathogenesis of prostatic adenoma. Several studies have been performed to test this hypothesis, both in humans and animals. The purpose of this review is to update available information, including our own ongoing studies. Morphological research has shown that cells infiltrating the adenoma are lymphocyte T, lymphocyte B and macrophages with a high proportion of lymphocyte T. Many of the inflammatory markers, such as lymphoquines (IL1, IL2, IL4, IL6, IL13), are elevated in the adenoma tissue as are some growth factors (EGF, TGF alpha, IFN gamma, TGF beta). The general impression is that an inflammatory process is activated in the adenoma during growth and maturing. It has also been proved that this inflammatory process could be modified with treatment and, in our case, with the lipido-sterolic extract of Serenoa Repens.

Humans↗

PubMed2000

Cl(-)-dependent excitotoxicity is associated with 3H2O influx in chick embryonic retina.

The aim of this study was to show that Cl(-)-dependent excitotoxicity, with its characteristic cell swelling, involves actual water influx into the intracellular compartment. Taking advantage of the Ca2+ omission paradigm of Cl(-)-dependent excitotoxicity, in the chick embryonic neural retina ex vivo, which is associated with toxicity levels (lactate dehydrogenase (LDH) release) considerably higher than those seen after simple exposure of the retinas to glutamate agonists, we have demonstrated that an intracellular water intake of 4.2 microl into retinal cells is associated with 13.3% total retinal LDH release. The fact that mannitol blocks both water inflow and LDH release appears to link both events from a pathogenic point of view.

Animals↗

PubMed2000

Ca2+-dependent kainate excitotoxicity in the chick embryonic neural retina ex vivo.

The chick embryonic neural retina ex vivo has been singled out as a unique example of Cl(-)-dependent/Ca2+-independent excitotoxicity. However, after continuous incubation with 100 microM kainate, we have demonstrated the susceptibility of the chick retina to Ca2+-mediated damage, which becomes apparent after 12 h of exposure to the agonist in the absence of Cl-. Of the 20.8% lactate dehydrogenase released after 24 h incubation with kainate, some 11% is Cl(-)-dependent and the rest (9.8%) is presumably Ca2+-dependent. Upon omission of both Cl- and Ca2+, a 5% residual toxicity can still be detected after 24 h. This can be overcome by inclusion of EGTA in the incubation medium to neutralize Ca2+ released during incubation. A Ca2+-dependent toxicity mechanism is then operative in the embryonic chick retina ex vivo.

Animals↗

PubMed2000

Guanine nucleotides block agonist-driven 45Ca2+ influx in chick embryo retinal explants.

AMPA (EC50 = 1.0 x 10(-6) M) and NMDA (EC50 = 1.3 x 10(-4) M) trigger 45Ca2+ influx in 13-day chick embryonic retinal explants. This agonist-driven cationic flux is specifically inhibited by typical competitive antagonists, such as 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 2-amino-7-phosphonoheptanoate (AP7), respectively. Guanine nucleotides, with different degrees of phosphorylation, namely 5'-GMP, guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS), guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) and 5'-guanylyl-imidodiphosphate (GppNHp), are also efficient blockers of 45Ca2+ influx. These results confirm the antagonistic behavior of guanine nucleotides towards ionotropic glutamate receptors and suggest a convenient experimental approach for screening of novel agonists and antagonists.

2-Amino-5-phosphonovalerate↗

PubMed2000

Hepatitis C virus RNA in kidney biopsies from infected patients with renal diseases.

Hepatitis C virus (HCV) infection has been associated with several renal pathologies, including membranoproliferative and membranous glomerulonephritis. Although the presence of HCV proteins has been reported, there are no data concerning detection of the viral RNA in renal cells from HCV-infected patients with kidney disease. In this report we analysed, by in situ hybridization, the presence of HCV RNA in renal biopsies from 10 patients who were positive for antibodies to HCV (anti-HCV) and serum HCV RNA positive, and from four patients without HCV infection, with different renal disease. HCV RNA was detected in the renal biopsies from all of the 10 HCV-infected patients. Hybridization signals were detected in the tubular and capillary endothelial cells. No hybridization signals were found in the renal biopsies of the four anti-HCV-negative patients. In conclusion, our results demonstrate that HCV RNA is common in kidney cells of patients with renal diseases who are infected with HCV. The presence of HCV RNA is not necessarily associated with a pathogenetic consequence.

Adult↗

PubMed1999

Chick kainate binding protein lacks GTPase activity.

Chick kainate binding protein was solubilized from cerebellar membranes and purified (x19) by use of two chromatographic steps. Measurements of [3H]kainate binding and GTPase activity in the different fractions reveal a consistent decrease of GTPase activity as the purification proceeds so that no GTPase is detectable after the final purification step. This fact, in the context of the differential involvement in nucleotide recognition of some critical amino acid residues in the p-loop motif of GTPases and in the guanine nucleotide-binding sequence of ionotropic glutamate receptors, together with significant discrepancies concerning the activity of individual nucleotides, suggests that both guanine nucleotide-recognizing sequences are unlikely to be alternative expressions of the same functional domain.

Animals↗

PubMed1999

Guanine nucleotides, including GMP, antagonize kainate responses in Xenopus oocytes injected with chick cerebellar membranes.

Injection of chick cerebellar membranes, rich in kainate binding sites, into Xenopus oocytes resulted in the structural integration of chick membrane patches into the oocyte plasma membrane that could be easily identified by specific immunofluorescent staining. Application of kainate to the oocyte perfusion medium, under voltage-clamp conditions, induced dose-dependent (EC50 = 87+/-14 microM) inward currents, confirming the functional incorporation to the oocyte of kainate-driven channels. Responses to kainate were consistently nondesensitizing and strongly potentiated by cyclothiazide, suggesting the selective involvement of alpha-amino-3-hydroxy-5-methyl-4isoxazolepropionate (AMPA)-preferring receptors. Binding experiments with (S)-[3H]AMPA confirmed the presence in the chick membrane preparation of low-affinity AMPA receptors (K(D) = 278 nM) amounting to <2% of the total population of kainate binding sites. A tenfold concentration of guanine nucleotides, with different degrees of phosphorylation, blocked the responses to 100 microM kainate by approximately 90%. In the case of GMP, additional concentration-inhibition studies yielded an IC50 of 180+/-11 microM. Our results illustrate the apparent failure of kainate-binding proteins to form functional channels, even when maintaining their own native membrane environment, and confirm the antagonistic behavior of guanine nucleotides, including GMP, toward glutamate receptors, in agreement with previous results of ligand-binding experiments and, more interestingly, with the marked neuroprotective effects of some guanine nucleotides in different excitotoxicity experimental paradigms.

Animals↗

PubMed1998

Guanine nucleotides protect against kainate toxicity in an ex vivo chick retinal preparation.

Ex vivo preparations of chick neural retina have been successfully used in the assessment of excitotoxicity and in the evaluation of the protective effects of glutamate antagonists. Using a variation of this approach, and measuring the acute and delayed toxic effects of kainate (KA) in terms of lactate dehydrogenase release, we have shown that guanine nucleotides behave as effective neuroprotecting agents. The anti-excitotoxic potency of guanine nucleotides (in the case of GMP and GDPbetaS it is about 100 times lower than that of DNQX, a powerful kainate antagonist) correlates well with their ability to displace KA from retinal KA receptors.

Animals↗

PubMed1998

Degos disease in a patient with acquired immunodeficiency syndrome.

Malignant atrophic papulosis is a rare disorder characterized by pathognomonic cutaneous lesions that consist of infarctive thrombosis. Visceral involvement often occurs; the gastrointestinal tract and the central nervous system are most frequently involved. Malignant atrophic papulosis has not been previously described in an AIDS patient. We describe a 58-year-old homosexual man with AIDS who developed typical cutaneous lesions of malignant atrophic papulosis. No visceral involvement has been detected in 2 years.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Cutaneous manifestations of infection by nontuberculous mycobacteria.

Cutaneous infections by nontuberculous mycobacteria (NTM) are not usual but their relative importance has changed during the last few years and still further changes are expected. This study comprised 13 patients from whom NTM were recovered from skin biopsy specimens, sinus exudates or cutaneous abscesses. All samples were processed according to standard methods, and the isolates were identified by biochemical testing. Skin biopsy specimens, when available, were processed for histopathological study. The clinical records of the patients were reviewed, and the relevant clinical, microbiological and epidemiological data collected. The clinical manifestations were noted to be relatively nonspecific and consisted of draining sinuses, abscesses, ulcers and nodules with multicentric or sporotrichoid patterns. Tissue culture isolated Mycobacterium fortuitum complex in nine patients, M. avium in three, and M. marinum in one. In the nine patients studied by histopathology, various patterns were observed. These included dermo-hypodermal abscesses, suppurative granulomas, tuberculoid granulomas and granulomas with a perifollicular distribution. Cutaneous lesions can thus be the first and the only sign of NTM disease, and culture still remains the definitive diagnostic procedure.

Adult↗

PubMed1998

Histopathology of cutaneous reaction to granulocyte colony-stimulating factor: another pseudomalignancy.

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic growth factor (HGF) with many applications in cancer therapy. The most important applications are reduction in the incidence of febrile neutropenia, acceleration of neutrophil recovery after chemotherapy or bone marrow transplantation, and mobilization of progenitor cells. Many cutaneous adverse reactions associated with HGF have been reported in recent years, including injection site reactions, pyoderma gangrenosum, Sweet's syndrome, cutaneous leucocytoclastic vasculitis, and widespread folliculitis. The presence of large histiocytes on the dermis between collagen bundles has been proposed as a characteristic histopathologic finding in cutaneous eruptions secondary to granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor. We report on a patient with a high-risk ductal infiltrating carcinoma of the breast who received high-dose chemotherapy (HDC) with peripheral blood progenitor cell (PBPC) rescue. The patient received G-CSF after PBPC for a faster granulocyte recovery. She developed a cutaneous eruption located on back, buttocks, axillae, groin and sites where electrocardiography electrodes had been placed. From the histopathological point of view, the eruption was characterized by the presence of numerous large, atypical histiocytes in the dermis with several mitotic figures, mimicking involvement of the dermis by a malignant process.

Breast Neoplasms↗

PubMed1998

In vivo sister chromatid differentiation and base line sister chromatid exchanges in Channa punctatus.

An in vivo system for differentially stained sister chromatids by incorporating 5' Bromo 2' deoxyuridine at two consecutive round of DNA replication has been developed in C. punctatus. The base line developed frequency of sister chromatid exchanges (SCEs) was found to be 0.038 SCE/chromosome. This low baseline frequency of SCEs could be useful in detecting genotoxicity of pollutants in aquatic medium.

Animals↗

PubMed1997

Molecular modeling of (E)-1-alkyl-4(3)-[2-(1H-azolyl)vinyl]-pyridinium salts and evaluation of their behavior towards choline acetyltransferase.

A new type of extended pi-system aza-analogue of (E)-4-[2-(1-naphthylvinyl)]-1-substituted pyridinium salts (NVP+) has been designed and its inhibitory activity towards choline acetyltransferase (ChAT) has been evaluated in vitro. Among the several examples of the title quaternary salts synthesized 2 and 3, the indolylvinylpyridinium salt 2e is the only one to show a very low ChAT inhibition. The molecular modeling study is highly illustrative of their behavior towards ChAT and interaction with the recognition site. Thus, several selected cations together with the reference NVP+ compound 1a were studied at the PM3 and AM1 levels respectively. At the global minima, all the compounds are planar, which, from the electron charge distribution, shows a degree of polarization similar to the NVP+ model compound 1a. However, the fitting of all optimized structures indicated that only the indole derivative 2e showed the same aromatic fragment orientation as 1a, which allows us to define a volume that is not accessible to ligands in the enzyme and consequently to a refined model of the choline acetyltransferase recognition site.

Animals↗

PubMed1996

Glomerular up-regulation of EIIIA and V120 fibronectin isoforms in proliferative immune complex nephritis.

Fibronectin: (FNs) comprise a family of adhesive glycoproteins that are prominent components of mesangial extracellular matrix and accumulate during glomerular injury. By alternative splicing of an unique mRNA precursor, various FN isoforms can be originated. In rat, three regions of the molecule are involved: EIIIA, EIIIB and V. Because specific FN isoforms are expressed in embryogenesis and wound healing, conditions characterized by cell migration and adhesion, we examined the pattern of FN isoforms in the mild and severe phases of a progressive immune complex proliferative nephritis in rats. We constructed specific probes to analyze the splicing pattern of FN pre-mRNAs by ribonuclease protection assays. FN mRNAs containing EIIIA, EIIIB and V regions increased along, the progression of nephritis, though the increment of EIIIB-FN mRNA was modest. However, different regulation of all these isoforms was observed. The percentage of FN mRNA containing the EIIIA exon versus total FN increased with the severity of the disease, while the percentage of FN mRNA containing the EIIIB exon decreased. Relative V-FN mRNA expression versus total FN mRNA increased only in the severe phase. By means of specific antibodies we also studied the presence of EIIIA, EIIIB and V-FN proteins in the kidney. In the normal glomerutus, EIIIA-FN protein was barely detectable in the mesangium, increasing in the mild phase of nephritis. In the severe phase of nephritis, increased EIIIA-FN was localized in the mesangium, in Bowman's capsule and in crescents. By contrast, EIIIB-FN protein in the glomerulus was absent even in the severe phase. V120-FN protein, an isoform that mediates the attachment of leukocytes through the VLA-4 integrin, was present in the mesangium and glomerular capillary loops in control animals, and increased in the severe phase of nephritis, coinciding with a strong leukocyte infiltration. In conclusion, our results show that during immune glomerular injury there were marked changes in the pattern of FN isoforms expression. Since those isoforms, particularly V120 isoform, are important in cell adhesion and migration, their up-regulation may facilitate the recruitment of cells into the injured glomeruli. The blockade of the interaction between V120-FN and infiltrating leukocytes may represent a new approach to the treatment of nephritis.

Alternative Splicing↗

PubMed1996

Unilateral areolar sebaceous hyperplasia in a male.

We report a case of areolar sebaceous hyperplasia involving the right mammary areola in a 49-year-old male. Areolar sebaceous hyperplasia, an uncommon entity first described by Catalano and Ioannides in 1985, is characterized clinically by yellowish thickening of the areolae and histopathologically by large numbers of mature hyperplastic sebaceous lobules connected to the skin surface through short, hairless infundibular canals. Since its original description, only two additional reports have been published. To our knowledge, our patient is the first reported of areolar sebaceous hyperplasia in a male.

Humans↗

PubMed1996

Interferon-inducible protein-10 is highly expressed in rats with experimental nephrosis.

Interferon-inducible protein (IP)-10 is a small glycoprotein member of a family of chemotactic cytokines structurally related to interleukin-8. We have recently described the induction of IP-10 mRNA in mouse mesangial cells stimulated with lipopolysacharide, interferon-gamma, and tumor necrosis factor-alpha. To further evaluate a possible role for this chemokine in renal injury, we have studied IP-10 in an experimental model of nephrosis induced in rats by adriamycin. High levels of glomerular IP-10 mRNA expression and glomerular and tubulointerstitial IP-10 protein were seen on day 21, coinciding with maximal proteinuria, glomerular tumor necrosis factor mRNA expression, and interstitial cellular infiltrates. Maintenance on a low protein diet not only delayed the appearance of proteinuria and interstitial cellular infiltrate but also decreased glomerular IP-10 mRNA expression. Isolated normal glomeruli and cultured glomerular epithelial and mesangial cells from normal rats expressed IP-10 mRNA upon stimulation with 100 U/ml interferon or 1 microgram/ml lipopolysaccharide for 3 hours. IP-10 mRNA expression was also inducible by lipopolysaccharide and cytokines in NRK 49F renal interstitial fibroblasts and, to a lesser extent, in NRK 52E tubular epithelial cells. Furthermore, IP-10 protein was inducible in murine mesangial cells. We conclude that IP-10 is highly inducible in vitro and in vivo in resident glomerular and tubulointerstitial cells. IP-10 may participate in the modulation of renal damage in experimental nephrosis.

Animals↗

PubMed1995

Cutaneous tuberculosis: a clinical, histopathologic, and bacteriologic study.

BACKGROUND: In recent years cutaneous infections with Mycobacterium tuberculosis with an atypical clinical appearance have become more common because of the increasing number of immunocompromised patients. OBJECTIVE: We report the clinical, histopathologic, and bacteriologic data of 11 patients with several forms of cutaneous tuberculosis seen during the past 14 years. METHODS: Patients from whom M. tuberculosis was isolated from culture of skin biopsy specimens, sinus drainage, or material aspirated from cutaneous abscesses were included. In all but two patients a biopsy specimen was obtained for histopathologic study. All but one patient received combined antituberculous therapy. RESULTS: The clinical diagnoses were scrofuloderma (four cases), cutaneous miliary tuberculosis (two), lupus vulgaris (two), tuberculous gumma (two), and one unclassified. All but three patients had evidence of either previous or simultaneous tuberculous foci other than in the skin. Histopathologic findings varied according to the type of cutaneous tuberculosis. CONCLUSION: In some patients with cutaneous tuberculosis, lesions are atypical in appearance because of immunodeficiency. Culture for M. tuberculosis should be performed in all suspected cases, even in those in whom special stains for acid-fast bacilli are negative.

Abscess↗

PubMed1995

Malignant hidroacanthoma simplex. A case report and literature review.

A 73-year-old woman with a malignant hidroacanthoma simplex on her right lower limb is reported. The lesion was immunohistochemically studied. Carcino-embryonic antigen and epithelial membrane antigen were found in the luminal border of ductal structures within the aggregations of neoplastic cells. We review the literature on this subject.

Acrospiroma↗