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Biomedical subjects

J Gil

Publications and source records attributed to J Gil.

At least 145 records · Page 8Linked to original sources
PubMed1997

Inhibition of DNA synthesis by aspirin in Swiss 3T3 fibroblasts.

In Swiss 3T3 fibroblasts, aspirin inhibited proliferation induced by the complete mitogenic factors platelet-derived growth factor (PDGF) and bombesin. Aspirin decreased the maximum mitogenic effect of bombesin without modifying the concentration necessary to obtain half maximal DNA synthesis stimulation. In contrast, aspirin only decreased mitogenesis at subsaturating PDGF concentrations. The effect of aspirin was found to be concentration dependent. The half-maximal effect occurred at approximately 150 microM. The maximal inhibition was obtained when aspirin was added during the first hour after growth factor addition. At this time, both PDGF and bombesin induced prostaglandin E2 synthesis. PDGF induced much higher levels of prostaglandin E2 than bombesin. The inhibitory effects of aspirin on PDGF or bombesin-stimulated DNA synthesis were counteracted by 280 nM prostaglandin E2. Aspirin effects were overcome by agents that increase cellular cyclic adenosine monophosphate levels but not by activation of protein kinase C. The significance of the antiproliferative action of aspirin might be associated with epidemiological data that show a reduced incidence of colorectal and other cancers after aspirin treatment.

3T3 Cells↗
PubMed1997

The relationships among performance measures in the selection of diagnostic tests.

Diagnostic tests are typically evaluated using performance measures, such as sensitivity, specificity, positive and negative predictive values, accuracy, and likelihood ratios. Numerous criteria have been suggested as to the types of diagnostic scenarios for which each of these measures is most important. Reports in the medical literature will often characterize a test by the values of some, but not all, of these performance measures. At times the unreported measures can be of interest in evaluating whether to use a test. A set of formulas is presented which, in many cases, enables one to determine unreported measures from those provided, for example, accuracy from sensitivity, specificity, and positive predictive value. The relationships between the measures of diagnostic test effectiveness and the prevalence of disease are discussed. An application to the diagnosis of acute myocardial infarction with new biochemical markers is used to illustrate these relationships.

Biomarkers↗
PubMed1997

Effect of ultrafast Papanicolaou staining on nuclear and textural features in breast cancer cytology.

OBJECTIVE: To compare quantifiable cytologic features of mammary lesions prepared using the Ultrafast Papanicolaou, Diff-Quik and Papanicolaou methods. STUDY DESIGN: Thirteen patients with mammary lesions were studied; the majority had histopathologic diagnoses of infiltrating ductal carcinoma. For each patient, three specimens were prepared, using (1) Diff-Quik staining after air drying, (2) Papanicolaou staining after wet fixation, and (3) the Ultrafast Papanicolaou procedure. Descriptors of nuclear size, shape and texture were computed from an average of 61.9 normalized nuclear images per specimen. Differences between preparation methods were analyzed using two-way analysis of variance. RESULTS: While differences in nuclear size, shape and texture existed between the three cytologic staining methods, only form factor varied significantly between conventional and Ultrafast Papanicolaou stain. Nuclear areas were larger in Ultrafast Papanicolaou specimens than conventional Papanicolaou specimens, but this difference was not statistically significant. CONCLUSION: The Ultrafast Papanicolaou procedure improves on conventional Papanicolaou staining in terms of speed, with no important quantifiable differences in nuclear morphology.

Analysis of Variance↗
PubMed1996

Nitric oxide inhibits DNA synthesis and induces activation of poly(ADP-ribose) polymerase in cultured rat hepatocytes.

Incubation of cultured rat hepatocytes with sodium nitroprusside or SIN-1, two nitric oxide (NO) donors, inhibited the mitogenic action of hepatocyte growth factor in a dose-dependent manner. The addition of 100 microM reduced hemoglobin, which is known to absorb NO, or the presence of 20 microM 1,5-isoquinolinediol, a poly(ADP-ribose) polymerase (PARP) inhibitor, decreased the cytostatic effects of SIN-1. By labeling the hepatocytes with [2-3H]adenine we studied whether nitric oxide induces ADP-ribosylation of proteins in a whole-cell system. At 0.4 mM, sodium nitroprusside increased the [3H]adenine labeling of two proteins of 116 and 130-135 kDa. This effect was time-dependent and was detected after 2 h. Only the 116-kDa protein was recognized by three different antibodies against poly (ADP-ribose) polymerase in Western blot assays. These results demonstrate that NO has antimitogenic effects in cultured hepatocytes and that its action could be mediated by PARP activation.

Animals↗
PubMed1996

Characterization and purification of a protein kinase C substrate in human B cells. Identification as lymphocyte-specific protein 1 (LSP1).

Incubation of B-chronic lymphocytic leukemia (B-CLL) cells with phorbol esters resulted in the phosphorylation of two major PKC substrates, MARCKS (myristoylated, alanine-rich C kinase substrate) and MRP (MARCKS-related protein), and of a third protein, with an apparent m.w. of 60,000 that was the most prominent protein kinase C substrate in these cells. p60 phosphorylation was time and PMA dose dependent, and was induced by cell-permeable diacylglycerol, but not by inactive phorbol esters. Two-dimensional electrophoretic analysis of the protein phosphorylation pattern from the B cell line CESS demonstrated the identity between the p60 protein expressed in this cell line and that expressed in B-CLL cells. p60 was purified from CESS cells and peptide microsequencing of this protein revealed that it was lymphocyte-specific protein 1 (LSP1), that is here characterized as the most prominent protein kinase C substrate in B cells.

Actins↗
PubMed1996

Hepatocyte growth factor and transforming growth factor beta regulate 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase gene expression in rat hepatocyte primary cultures.

Hepatocyte growth factor (HGF) and transforming growth factor beta (TGF-beta) are believed to be of major importance for hepatic regeneration after liver damage. We have studied the effect of these growth factors on fructose 2,6-bisphosphate (Fru-2,6-P2) levels and the expression of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (6PF2K/Fru-2,6-BPase) in rat hepatocyte primary cultures. Our results demonstrate that HGF activates the expression of the 6PF2K/Fru-2,6-BPase gene by increasing the levels of its mRNA. As a consequence of this activation, the amount of 6PF2K/Fru-2,6-BPase protein and 6-phosphofructo-2-kinase activity increased, which was reflected by a rise in Fru-2,6-P2 levels. In contrast, TGF-beta decreased the levels of 6PF2K/Fru-2,6-BPase mRNA, which led to a decrease in the amount of 6PF2K/Fru-2,6-BPase protein and Fru-2,6-P2. The different actions of HGF and TGF-beta on 6PF2K/Fru-2,6-BPase gene expression are concomitant with their effect on cell proliferation. Here we show that, in the absence of hormones, primary cultures of hepatocytes express the F-type isoenzyme. In addition, HGF increases the expression of this isoenzyme, and dexamethasone activates the L-type isoform. HGF and TGF-beta were able to inhibit this activation.

Animals↗
PubMed1996

Morphometry of capillaries in three zones of rabbit lungs fixed by vascular perfusion.

BACKGROUND: In large lungs in the upright position, three functional conditions originated by gravity-related changes in the arterial (Pa) and venous (Pv) pressures with respect to alveolar air pressure (PA) are defined as follows: Zone 1 (apex), where PA > Pa > Pv, Zone 2 (middle), where Pa > PA > Pv, and Zone 3 (bottom), where Pa > Pv > PA. This article attempts to clarify the anatomic correlates of these "zonal" changes. METHODS: Rabbit lungs were placed in one of these zones by adjusting the inflation, pulmonary arterial and left atrial pressures and fixed by vascular perfusion of osmium to preserve the original configuration of alveolar surfaces and blood vessels. The specimens were analyzed by electron and scanning microscopy and by morphometry of the capillary lumina and septal thickness. RESULTS: We noticed the existence of large isolated corner vessels and of corner pleats of the alveolar wall in Zones 1 and 2, but not in Zone 3. These pleats and corner vessels contained bundles of dilated capillaries. By re-construction of serial sections we found that these always represent functional, not anatomically-fixed shortcuts between arteries and veins which permit a bypass of parts of the alveolar capillary network. In Zones 1 and 2, which showed similar morphology, septal capillaries outside of the corners were partly closed and when open, frequently had slit-like configuration. In Zone 3, all septal capillaries were wide open, of circular outline and of similar dimensions. Morphometry showed great dissimilarities of capillary size in Zones 1 and 2, and homogeneity in Zone 3, as proven by analysis of the size distribution curve of capillary sizes. CONCLUSIONS: There are substantial reversible morphological changes in the configuration and dimensions of capillaries in the three zones, involving differences in capillary diameter, number of capillaries open and homogeneity of capillary size. Of particular interest are the corner vessels and septal corner pleats present in Zones 1 and 2, which represent multiple, small functional arteriovenous shortcuts whose function is to maintain the patency of the right-to-left vascular path during high alveolar air pressures. It is noted that human patients placed in a respirator have their whole lungs in Zone 2. The pleat has a potential for working as an efficacious gas exchanger.

Animals↗
PubMed1996

Age-related changes in the soluble and the membrane-bound Tyr-aminopeptidase activities in several areas of the male and female rat brain.

It has been recently suggested that enkephalins might play a normal role in the regulation of cellular development in brain. Since the major pathway of enkephalin degradation seems to occur under the action of aminopeptidases, in the present paper we describe the changes in Tyr-aminopeptidase activities during several stages of the rat (male and female) brain development (9, 12, 15, 20 and 25 days postbirth). The enzyme activities (soluble and membrane-bound) were detected using Tyr-2-naphthylamide as substrate. No sexual differences were observed. However, significant rises from the 9th to the 15th postnatal day in the soluble peptidase activity were appreciated. Aminopeptidase M shows decreases in the activity with age. It is suggested that not only the enkephalins but also the enkephalin-degrading enzymes could play a part in the maturation of the rat brain.

Aging↗
PubMed1996

An iterative algorithm for cell segmentation using short-time Fourier transform.

In this paper, an iterative cell image segmentation algorithm using short-time Fourier transform magnitude vectors as class features is presented. The cluster centroids of the magnitude vectors are obtained by the K-means clustering method and used as representative class features. The initial image segmentation classifies only those image pixels whose surrounding closely matches a class centroid. The subsequent procedure iteratively classifies the remaining image pixels by combining their spatial distance from the regions already segmented and the similarities between their corresponding magnitude vectors and the cluster centroids. Experimental results of the proposed algorithm for segmenting real cell images are provided.

Algorithms↗
PubMed1996

[Pseudomonas spp. infections in patients with HIV infections].

BACKGROUND: The aim of this study was to describe the characteristics of the infections by Pseudomonas spp. observed in patients with HIV infection in Spain. METHODS: A retrospective study was performed of the isolations of Pseudomonas spp. in microbiologic samples of patients with HIV infection in three hospitals from Mallorca, Spain, since 1986. RESULTS: Twenty-nine patients with some positive culture for Pseudomonas were reviewed. In 20 cases the infection presented in advanced stages of the disease when the patient fulfilled AIDS criteria. The most frequent foci in both community acquired and nosocomial infection was respiratory (16 and 3 cases, respectively). Fifty percent of the cases presented bacteremia. The classically described predisposing factors for infection by this germ were presented in 19 patients. Pseudomonas aeruginosa was the most frequently isolated type (22 cases). Only 5 patients received the appropriate treatment on admission. Clinical cure was achieved in 23 patients, with recurrence being observed in 10. Five patients died in relation to the infection. CONCLUSIONS: Infections by Pseudomonas spp. in Spain appear to have increased in frequency in patients with HIV infection in the last decade. These infections appear in advanced phases of the disease and mainly involve the lung, with high rates of bacteremia and a high number of recurrence. Empiric treatment of patients with advanced HIV infection with suspicion of bacterial infection should include antipseudomonic drugs.

Adult↗
PubMed1995

Ovarian dysplasia in epithelial inclusion cysts. A morphometric approach using neural networks.

BACKGROUND: Ovarian dysplasia has been described in the ovarian surface epithelium by histologic and morphometric studies. This study evaluates ovarian dysplasia in epithelial inclusion cysts adjacent to overt carcinoma and also incidentally found in ovaries removed for nonneoplastic diseases, including oophorectomies for family history of ovarian cancer, using an artificial neural network. METHODS: Histologic sections from 37 ovaries of which 26 were diagnosed with dysplasia in epithelial inclusion cysts (10 adjacent to carcinoma and 16 incidental) and 11 with benign epithelial inclusion cysts were evaluated by tracing nuclear profiles and assessing measures of nuclear area, shape, and texture. These sections were analyzed using artificial neural networks and also statistically using the Kruskal-Wallis test with the Dunn procedure to compare the morphologic similarity of dysplasia found incidentally in inclusion cysts unrelated to carcinoma from that in inclusion cysts adjacent to carcinoma. RESULTS: Neither statistical nor artificial neural network analysis was able to distinguish between incidental and adjacent dysplasia. Both types differed significantly from the control cases. CONCLUSIONS: Neural networks are powerful classification tools when applied to multiple variables extracted from individual cases. In this study, they helped to substantiate the similarity between dysplasia found incidentally and that adjacent to ovarian carcinoma. Because dysplasia represents a potential precancerous lesion, its incidental finding may help identify patients at risk for developing ovarian carcinoma.

Female↗
PubMed1995

Role of the N-terminal region in covalent modification of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: comparison of phosphorylation and ADP-ribosylation.

The effect of cyclic AMP (cAMP)-dependent phosphorylation and ADP-ribosylation on the activities of the rat liver bifunctional enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2/FBPase-2), was investigated in order to determine the role of the N-terminus in covalent modification of the enzyme. The bifunctional enzyme was demonstrated to be a substrate in vitro for arginine-specific ADP-ribosyltransferase: 2 mol of ADP-ribose was incorporated per mol of subunit. The Km values for NAD+ and PFK-2/FBPase-2 were 14 microM and 0.4 microM respectively. A synthetic peptide (Val-Leu-Gln-Arg-Arg-Arg-Gly-Ser-Ser-Ile-Pro-Gln) corresponding to the site phosphorylated by cAMP-dependent protein kinase was ADP-ribosylated on all three arginine residues. Analysis of ADP-ribosylation of analogue peptides containing only two arginine residues, with the third replaced by alanine, revealed that ADP-ribosylation occurred predominantly on the two most C-terminal arginine residues. Sequencing of the ADP-ribosylated native enzyme also demonstrated that the preferred sites were at Arg-29 and Arg-30, which are just N-terminal to Ser-32, whose phosphorylation is catalysed by cAMP-dependent protein kinase (PKA). ADP-ribosylation was independent of the phosphorylation state of the enzyme. Furthermore, ADP-ribosylation of the enzyme decreased its recognition by liver-specific anti-bifunctional-enzyme antibodies directed to its unique N-terminal region. ADP-ribosylation of PFK-2/FBPase-2 blocked its phosphorylation by PKA, and decreased its PFK-2 activity, but did not alter FBPase-2 activity. In contrast, cAMP-dependent phosphorylation inhibited the kinase and activated the bisphosphatase. These results demonstrate that ADP-ribosylation of arginine residues just N-terminal to the site phosphorylated by PKA modulate PFK-2 activity by an electrostatic and/or steric mechanism which does not involved uncoupling of N- and C-terminal interactions as seen with cAMP-dependent phosphorylation.

Adenosine Diphosphate Ribose↗