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S Gil

Publications and source records attributed to S Gil.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Post-transfusion purpura. Description of 2 cases diagnosed at the same hospital in a 6-month period].

Two new cases of postransfusional purpura diagnosed at the same hospital within the space of six months are described. This finding supports the idea that despite being an infrequent disorder, a substantial rise in PTP cases inside and outside our country, has been recorded. This increase has coincided with a greater interest in platelet immunology and, particularly, in complications associated with blood transfusion. Both cases constitute an example of the clinical epidemiological profile which characterizes the patients suffering from this disorder. The patients are two women aged 74 and 60 years who after 8 and 9 days, respectively, of being transfused with red cells developed a severe thrombocytopenia accompanied by generalized haemorrhagic diathesis. The serological studies performed revealed the presence, in both patients, of an HPA-1a platelet specific antibody. The platelet genotyping enabled us to confirm this specificity after detecting an HPA-1 (a-b+) platelet genotype. The treatment with immunoglobulins at high doses proved to be effective in both cases. The adsorption-elution experiments of the antibody versus HPA-1 (a + b) platelets were positive in the patient with the highest antibody titre (1024). This finding support the most recent hypothesis concerning the pathogenic mechanism of PTP. According to this theory, the antibody, which is detected in the acute phase of the PTP, would not yet have acquired the restricted specificity corresponding to it. This could enable it to react with a structure shared by the HPA-1a positive and HPA-1a negative platelets.

Aged↗
PubMed1995

Differential expression of five protein kinase C isoenzymes in FAO and HepG2 hepatoma cell lines compared with normal rat hepatocytes.

We analyzed the expression of five protein kinase C (PKC) isoforms in cytosolic and membrane fractions from normal rat hepatocytes compared with those of two tumorigenic cell lines FAO and HepG2. Western blots with PKC-specific isoenzymes polyclonal antibodies provide evidences for the presence of the five isoforms alpha, beta II, delta, epsilon and zeta in normal rat hepatocytes. In hepatoma cells, we show differences in the level of expression, the molecular sizes and the responses to Phorbol 12-myristate 13-acetate (PMA).

Amino Acid Sequence↗
PubMed1995

Effect of deoxymannojirimycin and Brefeldin A on Yersinia pseudotuberculosis invasin--eukaryotic cell interaction.

The cell surface receptors of the Yersinia pseudotuberculosis invasin protein are the alpha 3-6 beta 1 integrins. Invasin and the extracellular matrix protein fibronectin bind to the same or closely located sites on alpha 5 beta 1 integrin, although invasin bind with a much greater affinity. Invasin-integrin interaction promotes bacterial penetration into eukaryotic cells. Binding of fibronectin to its integrin receptor seems to be dependent on terminal oligosaccharides processing. In this paper, we have examined the effect of 1-deoxymannojirimycin (dMNJ), an inhibitor of Golgi alpha-mannosidases involved in processing of N-glycan precursors, and of Brefeldin A (BFA), a natural product of fungi which has profound effects on the structure and function of the Golgi apparatus, on invasin-cell interaction. We found that unlike fibronectin, the interaction of invasin with cells was resistance to dMNJ. However, preincubating cells with BFA caused a dose dependent inhibition of invasin-mediated cell entry, while cell invasion by Salmonella typhimurium was not affected.

1-Deoxynojirimycin↗
PubMed1995

Ischemia-triggered translocation and inactivation of protein kinase C isoforms in the fetal brain.

The kinetics of protein kinase C (PKC) translocation and down-regulation in the 20-day-old fetal brain following short and long episodes of maternal-fetal blood flow occlusion were examined. Restriction for up to 15 min increased the specific enzymatic activity in the membrane by 73%, indicative of translocation. After a 30-min restriction and a 2.5-h reperfusion the total PKC activity in the cytosol was reduced to approximately 50%, consistent with down-regulation/inactivation. The total membrane PKC activity remained unchanged. Several PKC isoenzymes, including alpha, beta 1, beta 2, epsilon, and zeta, but not gamma, were identified in the fetal brain on western blots using specific antibodies. Compared with postnatal day 15, a greater proportion of the fetal PKC isoforms, particularly alpha and epsilon, were membrane bound, alpha, beta 2, epsilon, and zeta, but not beta 1, were translocated into the membrane compartment after episodes of ischemia alone or ischemia and reperfusion. There were no major identifiable proteolytic fragments in the 50-kDa region. Major losses in the total enzymatic activity were encountered in both cytosol and membrane fractions after storage of the enzyme for 10 days at 4 degrees C. These losses were less profound in membrane fractions from ischemic than control animals, suggesting a relative sparing of activity in the membrane as a result of the insult. Preincubation of DEAE-purified PKC for 30 min at 50 degrees C resulted in enzyme inactivation. This was accompanied by a size reduction (approximately 2-5 kDa) in the gel migration of several isozymes in both cytosol and membrane fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Molecular characterization of a carboxy-terminal eukaryotic-cell-binding domain of intimin from enteropathogenic Escherichia coli.

A eukaryotic cell-binding domain from the intimin (Int) polypeptide of enteropathogenic Escherichia coli O127 (EPEC) was investigated. Derivatives of the carboxy-terminal 280-amino-acid domains of Int (Int-EPEC280) and the Int homolog invasin (Inv) from Yersinia pseudotuberculosis (InvYP280) were fused to the E. coli maltose-binding protein (MBP), expressed, and purified. The smallest MBP-IntEPEC fusion protein that efficiently mediated binding to HEp-2 cells, monitored by using purified fusion proteins in fluorescence activated cell sorter analysis or by using fluorescent Covaspheres coated with purified fusions, contained the carboxy-terminal 150 amino acids of Int. Replacement of Cys-937 with Ser (IntEPEC280CS) destroyed the cell-binding activity of IntEPEC280. Covaspheres coated with MBP-IntEPEC280 were associated with HEp-2 cell microvilli but failed to induce actin accumulation underneath bound particles or cell spreading on coated plastic surfaces. MBP-IntEPEC280, but not MBP, MBP-IntEPEC280CS, or MBP-InvYP280, inhibited EPEC entry into HEp-2 cells.

Adhesins, Bacterial↗
PubMed1994

Identification of a molecule of Porphyromonas gingivalis that binds to Streptococcus gordonii.

The molecules that mediate the adherence of Porphyromonas gingivalis, a periodontal pathogen, to Streptococcus gordonii, a commensal plaque organism, were investigated. Outer membrane proteins of P. gingivalis were labelled with biotin, extracted by EDTA and reacted with S. gordonii cells. Interactive porphyromonas components were identified by SDS-PAGE of the S. gordonii cells followed by electroblotting and visualization of the adsorbed porphyromonas molecules with streptavidin-alkaline phosphatase. A P. gingivalis molecule of 35 kDa bound to S. gordonii. Monospecific polyclonal antibodies to the 35 kDa protein inhibited binding of P. gingivalis to S. gordonii by 71%. The antibodies also reacted with the P. gingivalis fimbriae, indicating that the 35 kDa molecule is antigenically related to, or associated with, the fimbriae.

Adhesins, Bacterial↗
PubMed1994

Imidazol-1-ylalkanoic acids as extrinsic 1H NMR probes for the determination of intracellular pH, extracellular pH and cell volume.

The synthesis and biological evaluation of a novel series of extrinsic probes for intracellular pH (pHi), extracellular pH (pHo) and cell volume determination by 1H NMR is described. Imidazol-1-ylacetate, malonate, 3-glutarate and 2-succinate esters were synthesized by reaction of imidazole with alpha-bromo esters or with alpha, beta-unsaturated esters. The corresponding acids were prepared by hydrolysis. Rat erythrocytes were readily permeable to methyl imidazol-1-ylacetate, moderately permeable to diethyl 2-imidazol-1-ylsuccinate and impermeable to diethyl 3-imidazol-1-yl-glutarate esters. Imidazol-1-ylacetic acid was the only acid derivative which penetrated the erythrocyte interior when added directly to the incubation medium. Transport of the permeable compounds to the erythrocyte interior was non-saturable up to 200 mM added compound. Addition of methyl imidazol-1-ylacetate or diethyl 2-imidazol-1-ylsuccinate esters to erythrocyte suspensions, resulted in hydrolysis to imidazol-1-ylacetic acid and 2-imidazol-1-ylsuccinic acid mono-ethyl ester in the intracellular and extracellular spaces, respectively. pHi and pHo were determined from the different chemical shifts of the H-2 proton of the acid derivatives in the intracellular (H-2i) and extracellular (H-2o) compartments. In addition, the relative intracellular and extracellular volumes could be calculated from the areas of the intracellular and extracellular H-2 resonances.

Animals↗
PubMed1994

Molecules of Streptococcus gordonii that bind to Porphyromonas gingivalis.

Interbacterial binding is considered an important colonization mechanism for many of the organisms that inhabit dental plaque. Porphyromonas gingivalis, a periodontal pathogen, can adhere to species that comprise early plaque, such as Streptococcus gordonii. In this study, the molecules of S. gordonii G9B that mediate binding to P. gingivalis were investigated. Biotinylated surface molecules of S. gordonii were extracted and mixed with P. gingivalis cells. Interactive streptococcal components were identified by SDS-PAGE of the P. gingivalis cells followed by electroblotting, and visualization of the adsorbed streptococcal molecules with streptavidin-alkaline phosphatase. S. gordonii molecules of 45 kDa and a doublet of 62/60 kDa were observed to bind to P. gingivalis. Polyclonal antibodies raised to the 62/60 kDa proteins inhibited the binding interaction. These antibodies demonstrated an antigenic relationship between the 62/60 kDa molecules and the 45 kDa protein. Both molecules were also antigenically related to, and may be breakdown products of, a larger molecule of 170 kDa which is antigenically related to the P1 antigen of S. mutans. Cloning and expression in Enterococcus faecalis of the gene for the P1-like molecule from S. gordonii M5 resulted in a phenotype that expressed the 62/60 kDa and 45 kDa antigens and was capable of binding to P. gingivalis. These results suggest that a P1-like molecule in S. gordonii is involved in adherence to P. gingivalis. Processing of the P1-like molecule into smaller fragments of 62/60 kDa and 45 kDa may be required for binding activity.

Animals↗
PubMed1993

Gangliosides stimulate synthesis of prostaglandin E2 and prostacyclin in fetal rat brain hemispheres after episodes of global intrauterine ischemia.

The ability of brain preparations from 20-day-old rat fetuses to synthesize prostanoids in vitro before and after interruption of the maternal-fetal blood flow was examined using a radioimmunoassay technique. Synthesis of thromboxane B2 (TxB; the stable thromboxane A2 metabolite) decreased with increasing restriction time; conversely, it was elevated with reperfusion. Synthesis of 6-keto prostaglandin F1 alpha (PGF; the stable prostacyclin metabolite) and prostaglandin E2 (PGE) prostanoids remained unchanged after 20 min restriction and through a 2 hr reperfusion period. Intraperitoneal administration of GM1 (45 mg/kg) into the pregnant rat, 3 hr before restriction, stimulated synthesis of PGE and reduced synthesis of TxB. A prostanoid vasoactive index (PVI), which reflects the relative proportion of the three prostanoids synthesized and asserts the vasoactive potential of the brain tissue, was established. A rise in this value was attained after intrafetal administration into the peritoneal cavity of either GM1, GM3, or isopropyl-GM1 (AGF44) gangliosides, each given at 40 micrograms dose in 5 microliters volume, and N-dichloroacetyl-sphingosine (LIGA20; 15 micrograms/5 microliters) ganglioside analog, 1 hr before restriction. The effect was primarily due to an increase in the capacity of fetal brain tissue to synthesize PGE and, to a lesser extent PGF, vasodilating prostanoids. The N-methyl-D-aspartate (NMDA) receptor-blocker MK801 (6.6 micrograms/2 microliters) and the platelet activating factor (PAF) receptor antagonist BN52021 (0.1 mumol/2 microliters), given by the same route, effectively raised by 60-80% the vasodilating potential of the brain tissue following ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Involvement of Porphyromonas gingivalis fimbriae in adherence to Streptococcus gordonii.

Adherence of Porphyromonas gingivalis to early plaque bacteria, such as Streptococcus gordonii, is considered an important colonization mechanism. The molecules that mediate this interspecies binding have not been determined. Fimbriae were prepared from P. gingivalis 33277 by mild agitation, ammonium sulfate precipitation and DEAE-Sepharose chromatography. In a nitrocellulose blot adherence assay, purified fimbriae inhibited S. gordonii G9B-P. gingivalis 33277 binding by up to 54%. In addition, fimbriae bound to S. gordonii cells in a dot-blot assay. Incubation of fimbriae with S. gordonii cells followed by washing, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), electroblotting and probing with P. gingivalis antibodies also revealed that the fimbriae bind to S. gordonii. In contrast, S. gordonii did not interact with fimbriae that were first subjected to SDS-PAGE and electroblotting or deposited on a nitrocellulose membrane, suggesting that conformational determinants of the fimbriae may be important in binding. The results indicate that binding between P. gingivalis and S. gordonii is mediated, at least in part, by the porphyromonads' fimbriae.

Bacterial Adhesion↗
PubMed1993

Detection of the apoptosis-suppressing oncoprotein bc1-2 in hormone-refractory human prostate cancers.

The oncoprotein encoded by bc1-2 is unique because of its intracellular location (a mitochondrial membrane protein) and apparent mode of action (suppression of apoptosis). To date, this oncogene has been associated only with the development of certain forms of human B-cell lymphoma. In this report, we describe our experience with a monoclonal antibody made against a synthetic peptide for bc1-2 that can recognize the bc1-2 protein and identify cells in human prostate glands expressing this proto-oncogene with in situ immunohistochemical procedures. These procedures were utilized to survey a series of 62 human tissues to evaluate whether bc1-2 might have a role in the developing prostate gland or in prostate oncogenesis. While all primordial epithelial cells in a fetal prostate gland immunostain for bc1-2, normal and hypertrophic prostate glands of the adult show bc1-2 expression restricted to the basal cells. All epithelial cells in areas of prostatic intraepithelial neoplasia were stained by this antibody, as were most (62%) localized invasive prostatic carcinomas. In contrast, all primary prostatic carcinomas and metastases obtained from metastatic prostate cancer patients after hormone treatment (hormone-refractory tumors) stained positive for bc1-2. This study demonstrates that the oncoprotein encoded by bc1-2 can be detected at sequential stages in the natural history of human prostate cancer. Since the bc1-2 oncoprotein is known to suppress the cellular response to apoptotic stimuli, it will be important to determine whether bc1-2 expression is a factor in the development of prostate cancers and in the survival of hormone-refractory prostate cancer cells.

Antibodies, Monoclonal↗