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S Gil

Publications and source records attributed to S Gil.

At least 37 records · Page 2Linked to original sources
PubMed2001

1,25(OH)2 vitamin D concentration in the plasma of Solanum glaucophyllum intoxicated rabbits.

OBJECTIVE: To test Solanum glaucophyllum calcinotic effects in adult New Zealand White rabbits in relation to cumulative dose and active principle concentration in plasma. DESIGN: An intoxication assay with controls. PROCEDURE: Rabbits were orally dosed with aqueous extracts of dry leaves of S glaucophyllum for 5, 7 or 9 days. During the experiment, body weight, calcaemia and phosphataemia were measured; retinal blood vessel calibre was observed by ophthalmoscopic examination of the ocular fundus. 1,25(OH)2 vitamin D plasma concentration was determined at the end of the experimental periods. Soft tissue calcium concentration and the presence of calcinotic lesions were studied after euthanasia. RESULTS: Toxic effects were evident in S glaucophyllum treated groups (loss of body weight, elevation of soft tissue calcium concentration, and presence of calcinotic lesions). Plasma 1,25(OH)2 vitamin D concentrations were negatively correlated with final body weight (r = -0.97; P < or = 0.001), and positively correlated with renal calcium concentration (r = 0.74; P = 0.02). There was also a significant regression of plasma 1,25 (OH)2 vitamin D concentration on the cumulative dose of S glaucophyllum (R2 = 0.87; P < or = 0.001). CONCLUSIONS: The procedure described here offers a sensitive and practical experimental model for the study of the pathogenesis of enteque seco.

Animals↗
PubMed2001

Reduction of no synthase expression and tumor necrosis factor alpha production in macrophages by amphotericin B lipid carriers.

The present study compared the abilities of different lipid carriers of amphotericin B (AMB) to activate murine peritoneal macrophages, as assessed by their capacities to produce nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha). Although AMB alone did not induce NO production, synergy was observed with gamma interferon but not with lipopolysaccharide. This synergy could not be explained by the mobilization of the nuclear activation factor NF-kappaB by AMB. On the other hand, AMB induced TNF-alpha production without a costimulator and no synergy was observed. Anti-TNF-alpha antibodies did not influence NO production, and an inhibitor of NO synthase did not affect TNF-alpha production, indicating that the production of one of these effector molecules was independent of that of the other. The incorporation of AMB into lipid carriers reduced NO and TNF-alpha production with all formulations but more so with liposomes than with lipid complexes. NO production was correlated with the induction of NO synthase II, revealed by Western blotting. The extent of association of AMB with macrophages depended on the formulation, especially on the AMB/lipids ratio: the higher the ratio was, the greater the AMB association with macrophages. However, there was no clear correlation between AMB association with macrophages, whether internalized or bound to the membrane, and immunostimulating effects. These results may explain the reduced toxicities of lipid-based formulations of AMB.

Adjuvants, Immunologic↗
PubMed2000

N-methyl bases of ethanolamine prevent apoptotic cell death induced by oxidative stress in cells of oligodendroglia origin.

A major reason for brain tissue vulnerability to oxidative damage is the high content of polyunsaturated fatty acids (PUFAs). Oligodendroglia-like OLN 93 cells lack PUFAs and are relatively insensitive to oxidative stress. When grown in serum-free defined medium in the presence of 0.1 mM docosahexaenoic acid (DHA; 22:6 n-3) for 3 days, OLN 93 cells release in the medium 2.6-fold more thiobarbituric acid-reactive substances (TBARS) after a 30-min exposure to 0.1 mM H2O2 and 50 microM Fe2+. Release of TBARS was substantially decreased by approximately 20 and 30% on coincubation with either 1 mM N-monomethylethanolamine or N,N'-dimethylethanolamine (dEa), respectively. The protective effect of dEa was concentration- and time-dependent and was still visible after dEa removal, suggesting a long-lasting mechanism of protection. After 24 h following H2O2-induced stress, cell death monitored by cell sorting showed 16% of the cells in the sub-G1 area, indicative of apoptotic cell death. DHA-supplemented cultures showed 35% cell death, whereas cosupplements with dEa reduced cell death to 12%, indicating cell rescue. Although the exact mechanism for this protection is not known, the nature of the polar head group and the degree of unsaturation may determine the ultimate resistance of nerve cells to oxidative stress.

Animals↗
PubMed2000

Effectiveness and safety of balloon dilation of the papilla and the use of an occlusion balloon for clearance of bile duct calculi.

OBJECTIVE: The purpose of this study was to describe a technique for percutaneous bile duct stone clearance by pushing the stones into the small bowel after balloon dilation of the papilla. SUBJECTS AND METHODS: During a 2-year period, 38 patients were treated percutaneously for stones in the biliary tree. Twenty-one patients were treated through a T tube or transcystic tract. Seventeen patients were treated through a transhepatic tract. Twenty-three patients had one stone each. Eight patients had two stones, and seven patients had three or more calculi. Stone size ranged from 3 to 16 mm in diameter (mean size, 6.7 nm). Balloon diameter based on the transverse diameter of the stones ranged from 7 to 18 mm (mean, 6.7 mm). An 11.5-mm occlusion balloon was used for pushing the stones through a 7- to 9-French vascular introducer. A catheter was left in the common bile duct from 1 to 6 days for external drainage. RESULTS: The technique was successfully used for clearance of stones in 36 (94.7%) of the 38 patients. With 29 patients, the procedure was performed with only one attempt. Two attempts were necessary for five patients, and three attempts were necessary for four patients. Two major complications were cholangitis and biliary pleural effusion. No deaths were related to the procedure. CONCLUSION: Percutaneous bile duct stone clearance by dilation of the papilla and evacuation of the stones in an antegrade fashion with an occlusion balloon is a safe and effective technique. It can be an alternative to basketing stones in selected patients.

Adult↗
PubMed1999

H2O2-induced apoptotic death in serum-deprived cultures of oligodendroglia origin is linked to cell differentiation.

When deprived of serum, oligodendroglialike (OLN 93) cells grown on poly-L-lysine-coated culture dishes cease to proliferate after 3 days and morphologically extend many fibers resembling morphologically differentiated, immature oligodendrocytes. At this time no cell death is apparent unless serum deprivation is extended for a period longer than 1 week. After 3 days in serum-deprived medium, treatment of cells with 1 mM H2O2 for 30 min facilitates apoptotic cell death, even when serum is added during the recovery period. Both serum-deprived, differentiated cells, and proliferating cells, respond to H2O2 by an initial growth arrest followed by growth resumption after 48 hr. However proliferating cells show resistance to the apoptotic effect of H2O2. This is correlated with growth arrest in the S phase at different stages of DNA replication, as well as with different timing of induced p21Waf1 expression. Thus, cells grown in serum, express elevated p21Waf1 protein levels after 4 hr, whereas serum-deprived, differentiated cells, only after 24 hr. The mRNA levels of p21Waf1 follow a similar timed pattern. Hence p21Waf1 may protect OLN 93 cells against the genotoxic effect of H2O2. The data suggest an intimate relationship between G1-arrest, morphological differentiation, and H2O2-mediated apoptosis.

Animals↗
PubMed1999

Hydrogen peroxide induces nuclear translocation of p53 and apoptosis in cells of oligodendroglia origin.

The observation that apoptosis is an inherent pathway in oligodendrocytes development coupled with the notion that wild-type p53 is expressed in these cells, prompted us to investigate the interrelationship between the two phenomena. Using a permanent oligodendroglia-like cell line (OLN 93), we examined the role of p53 protein in apoptosis following a DNA insult induced by a brief exposure to H2O2. A marked translocation of p53 from the cytosolic to the nuclear compartment was notable by 20 min, following a 5 min treatment with 1 mM H2O2 as identified by cell immunostaining. By 48 h following H2O2 addition, nearly 60% of the cells exhibited p53 in the nuclei. At this time, a large proportion of the cells underwent apoptosis as identified by DAPI nuclear staining. The genotoxic-induced p53 relocalization appeared to be cell cycle phase specific; thus OLN 93 cultures enriched for cells in the G0/G1 stage by serum starvation, and abundant in nuclear-associated p53, were more susceptible to H2O2-induced apoptosis than their untreated counterparts and than double thymidine block, G1/S enriched, cultures. Analysis of the expression of p53 downstream genes indicated that p21 and mdm2 were upregulated following p53 nuclear translocation. From the kinetics of protein accumulation, it appears that mdm2 enhancement accelerated the exit of p53 from the nucleus to the cytosol. Our results suggest that following stress, oligodendroglia-like cells are induced to undergo p53-dependent apoptosis, an event that coincides with p53 nuclear translocation and is cell-cycle related.

Animals↗
PubMed1999

The keratinocyte-derived cytokine IL-7 increases adhesion of the epidermal T cell subset to the skin basement membrane protein laminin-5.

Human epidermis contains a subset of epidermal T cells that can mount an immune response by migrating through the skin and into the peripheral lymphnodes to proliferate before re-entering the epidermis. The cytokine IL-7 is shown to be localized to the basement membrane of normal human skin. Furthermore, culturing in the presence of IL-7 causes increased adhesion of epidermal T cells but not peripheral blood T cells to the major epidermal basement membrane protein, laminin-5. The mechanism for increased T cell adhesion to laminin-5 is due, at least in part, to an increase in the cell surface expression of the integrin alpha3beta1. Epidermal T cells cultured in IL-7 that are strongly adherent to laminin-5 are shown by flow cytometry to consist of a variety of subsets; therefore, the increase in cell adhesion is not due to an outgrowth of one T cell subset during culturing. We hypothesize that in vivo, exposure to IL-7 is required for epidermal T cell adhesion to laminin-5.

Adult↗
PubMed1999

Doppler duplex color localization of osteoid osteomas.

We present two cases of osteoid osteoma in adolescent boys. The lesions were located in the proximal metaphysis of the right tibia and left femoral diaphysis respectively. Doppler duplex color study demonstrated clearly the highly vascular nidus and its feeding artery in one case and only the feeding artery in the second. We believe these are the first descriptions of osteoid osteomas assessed with Doppler duplex color, which was also used as guidance for the percutaneous localization and biopsy.

Adolescent↗
PubMed1999

Myelodysplastic syndrome: a search for minimal diagnostic criteria.

We have evaluated dyshemopoietic features in bone marrow (BM) samples obtained from healthy people aged over 50 without peripheral blood (PB) cytopenia patients and compared them with MDS patients. Control group displayed BM features of dyserythropoiesis and dysgranulopoiesis in up to 15 and 27% of the considered cell elements (P90) respectively, overlapping in part with MDS patients. Interobserver agreement in dyshemopoietic features was highest for BM blast cell and pathological sideroblast counts. An algorithm based on BM blast cell and pathological sideroblast counts that has been verified on 613 patients from different Spanish centers may be of help to improve reproducibility in Myelodysplastic syndrome (MDS) diagnosis.

Cells, Cultured↗
PubMed1998

Cellular interaction of integrin alpha3beta1 with laminin 5 promotes gap junctional communication.

Wounding of skin activates epidermal cell migration over exposed dermal collagen and fibronectin and over laminin 5 secreted into the provisional basement membrane. Gap junctional intercellular communication (GJIC) has been proposed to integrate the individual motile cells into a synchronized colony. We found that outgrowths of human keratinocytes in wounds or epibole cultures display parallel changes in the expression of laminin 5, integrin alpha3beta1, E-cadherin, and the gap junctional protein connexin 43. Adhesion of keratinocytes on laminin 5, collagen, and fibronectin was found to differentially regulate GJIC. When keratinocytes were adhered on laminin 5, both structural (assembly of connexin 43 in gap junctions) and functional (dye transfer) assays showed a two- to threefold increase compared with collagen and five- to eightfold over fibronectin. Based on studies with immobilized integrin antibody and integrin-transfected Chinese hamster ovary cells, the interaction of integrin alpha3beta1 with laminin 5 was sufficient to promote GJIC. Mapping of intermediate steps in the pathway linking alpha3beta1-laminin 5 interactions to GJIC indicated that protein trafficking and Rho signaling were both required. We suggest that adhesion of epithelial cells to laminin 5 in the basement membrane via alpha3beta1 promotes GJIC that integrates individual cells into synchronized epiboles.

Animals↗
PubMed1998

Direct administration and utilization of [1-13C]glucose by fetal brain and liver tissues under normal and ischemic conditions: 1H, 31P, and 13C NMR studies.

Three distinct, maternal-independent routes (e.g. intraamniotic, intraperitoneal and intracerebral), for [1-13C]glucose utilization by fetal brain and liver tissues, were examined by multinuclear magnetic resonance (NMR) spectroscopy before and after vascular occlusion of the maternal-fetal blood flow. Labeled lactate was the major glycolytic product by all routes, but in addition labeled TCA cycle products were also generated. Fractional 13C enrichment in both glucose and lactate were always higher in the ischemic state compared to controls using either one of the three routes studied. After intraperitoneal injection total glucose in the fetal brain was decreased by 85% after 20 min reperfusion following 20 min ischemia, but was elevated up to 170% after 60 min. [1-13C]glucose increased continuously by up to 370% after 60 min. Total glucose in the fetal liver remained unchanged while [1-13C]glucose increased up to 380%. Total lactate level in brain was 50-80% above the control apart from a transient increase (140%) notable after 40 min reperfusion. The kinetics of [3-13C]lactate followed a similar time course. At the same time when lactate was transiently increased in fetal brain, total lactate as well as 13C-labeled lactate showed a transient decrease in liver after 40 min. While the ways of mobilization of energy substrates for maintaining adequate metabolic activity in the fetal brain remain still unclear, the present 13C NMR studies suggest that both liver glucose and lactate can contribute to brain metabolism particularly under ischemic stress.

Adenosine Triphosphate↗
PubMed1997

Differential effect of vanadate on receptor-mediated endocytosis of the asialoglycoprotein receptor in hepatocytes from normal and diabetic rats.

Insulin-dependent diabetes has been shown to affect several aspects of receptor-mediated endocytosis. Since vanadate, a phosphate analogue, is known to exert insulin-like actions in target tissues, we studied the effects of vanadate on the endocytosis of the asialoglycoprotein receptor (ASGP-R) after its administration either in vivo (oral therapy) and/or in vitro by direct incubation of isolated hepatocytes with vanadate. The surface binding, internalization, and degradation of 3H-asialoorosomucoid (3H-ASOR), a prototype ligand of the ASGP-R, were decreased in diabetic rats by approximately 36.5%, 22.3%, and 12.9%, respectively. These values were normalized in diabetic rats treated by vanadate. Similarly, vanadate treatment normalized the biphasic dissociation of 3H-ASOR/ASGP-R complexes by restoring the rapid dissociation process. In contrast, vanadate treatment did not affect any of these endocytic parameters in normal rats. In vitro experiments were monitored by direct incubation of isolated hepatocytes with 10 mM vanadate. This incubation created an inhibitory effect on the endocytic parameters. In this work, we have demonstrated that vanadate treatment can reverse the alterations induced by diabetes on receptor-mediated endocytosis of the ASGP-R.

Animals↗
PubMed1997

Identification of a Streptococcus gordonii SspB domain that mediates adhesion to Porphyromonas gingivalis.

Porphyromonas gingivalis, a primary pathogen in adult periodontitis, may establish itself in the oral cavity by adhering to early plaque bacteria such as Streptococcus gordonii. Our previous studies (R. J. Lamont et al., Microbiology 140:867-872, 1994) suggested that this interaction is mediated by the SspB polypeptide, a member of the antigen I/II family of streptococcal surface proteins. S. gordonii was recently shown to express a second Ssp polypeptide (SspA) that resembles SspB and the structurally homologous antigen I/II polypeptide (Pac) of Streptococcus mutans. To determine if all of these related antigen I/II proteins interacted with P. gingivalis, SspA, SspB, and Pac were tested for adhesion to P. gingivalis cells. Both of the S. gordonii Ssp proteins bound labeled target cells, whereas the S. mutans Pac polypeptide did not, suggesting that antigen I/II-mediated binding of P. gingivalis by streptococci may be species specific. To investigate the molecular basis for this functional difference, the P. gingivalis binding domain of SspB was mapped. The binding properties of a family of truncated SspB polypeptides lacking C-terminal sequences were determined. In addition, the lack of binding activity exhibited by the Pac protein was exploited to construct and analyze chimeric SspB-Pac polypeptides. Both approaches revealed that the region defined by residues 1167 to 1250 of SspB was essential for P. gingivalis binding. This region of SspA and SspB is entirely conserved, consistent with the binding properties determined for these proteins. However, the corresponding region of Pac differs in both the primary sequence and predicted secondary structure, suggesting that the overall structure of this domain may define its functional activity.

Adhesins, Bacterial↗
PubMed1996

Five isoenzymes of protein kinase C are expressed in normal and STZ-diabetic rat hepatocytes: effect of phorbol 12-myristate 13-acetate.

Using isoenzyme-specific antisera, five Protein Kinase Cs (PKCs) were detected in cytosol and membrane hepatocytes from normal rats: PKC alpha (80 kDa), PKC beta II (40, 50, 55, 85 kDa), PKC delta (74, 76 kDa), PKC epsilon (95 kDa), PKC zeta (65, 70 kDa). STZ-diabetes induced a lower expression of the five PKCs, a higher localization in the cytosol, a preferential expression of PKC delta as the 76 kDa phosphorylated species and a decreased kinase activity towards Histone III-S. A 1 microM phorbol 12-myristate 13-acetate (PMA) incubation induced similar translocation to the membrane of PKCs alpha, native 85 kDa beta II and epsilon. The 74 kDa PKC delta was switched to the 76 kDa species, the normal form in STZ-diabetic cells. The truncated PKC beta II and PKC epsilon were unchanged.

Amino Acid Sequence↗
PubMed1996

Kinetic analysis of epidermal growth factor endocytosis in rat hepatocytes. Effects of diabetes.

In the present study we followed the different steps of epidermal growth factor receptor (EGF-R) endocytosis in freshly isolated rat hepatocytes. Hepatocytes exhibit two classes of surface EGF receptors consisting of approximately 5,000 high-affinity sites (Kd = 15 pM) and 166,000 low-affinity sites (Kd = 670 pM). Binding of labeled EGF to hepatocytes permeabilized by digitonin shows that 75% of the total EGF-R are localized at the cell surface. At 37 degrees C, hepatocytes continuously internalized and degraded EGF in spite of a down-regulation of cell surface receptors. The internalization rate constants measured as a function of a range 125I-EGF concentrations (0.01 - 5 nM) involving various degrees of EGF-R occupancy show superimposable curves. This indicates that the specific internalization rate of EGF-R complex is independent of receptor occupancy. Streptozotocin-induced diabetes reduces the number of low-affinity EGF-R to 50,000 and produces a complete loss of high-affinity sites. The dynamics of 125I-EGF endocytosis show that diabetic hepatocytes fail to down-regulate the surface EGF-R efficiently although the constant rate of internalization is not modified. Decreased down-regulation of EGF-R together with enhanced EGF endocytosis suggest a greater efficiency in EGF-R recycling in diabetic rat hepatocytes.

Animals↗