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Biomedical subjects

N García

Publications and source records attributed to N García.

At least 91 records · Page 5Linked to original sources
PubMed1993

Abnormal expression of anion exchanger genes in primary biliary cirrhosis.

BACKGROUND: Chloride-bicarbonate anion exchangers (AE) are thought to be essential to the generation of ion fluxes into biliary, salivary, pancreatic, and other secretions. In primary biliary cirrhosis (PBC), chronic cholestasis is frequently associated with pluriglandular exocrine failure. The present study examined the expression of AE genes in PBC at the messenger RNA (mRNA) level. METHODS: Two AE messages, i.e., AE1 and AE2 mRNAs, were analyzed by a polymerase chain reaction-based procedure in liver specimens and peripheral mononuclear cells of patients with PBC and control subjects (with normal livers or with miscellaneous liver diseases). RESULTS: AE1 mRNA was detected in only a few liver biopsy specimens of patients with PBC and control subjects, whereas AE2 mRNA was found in all liver specimens tested. In lymphoid cells, however, both transcripts were consistently detected. AE2 mRNA levels in liver as well as in lymphoid cells were significantly lower in PBC patients than in controls. In contrast to AE2 mRNA, AE1 mRNA levels were increased in lymphoid cells from patients with PBC. Interestingly, the levels of liver AE2 mRNA in a few PBC patients treated with ursodeoxycholic acid were within the range of the controls. CONCLUSIONS: The expression of AE genes is altered in patients with PBC. It is suggested that this disturbance may have a role in the cholestasis, exocrine failure, and immunodysfunction of PBC.

Adult↗
PubMed1993

Ribavirin in the treatment of chronic hepatitis C unresponsive to alfa interferon.

For the 30-50% of patients with chronic hepatitis C who do not respond to alpha-interferon therapy there is no alternative treatment. Some previously untreated patients have shown a biochemical response to ribavirin, but the antiviral effects of this substance on alpha-interferon-resistant cases is largely unknown. Twelve patients with chronic hepatitis C who had not responded to a 6-12 month course of alpha-interferon were included in this study. Oral ribavirin was administered at a dose of 16 mg/kg per day for 6 or 9 months. Aminotransferase levels had not significantly changed during interferon therapy but decreased significantly during ribavirin treatment (mean alanine aminotransferase at baseline, 102 +/- 18 IU/l vs. 55 +/- 14 IU/l at 6 months; P = 0.0001). Aminotransferase levels became normal in 6 cases (50%), significantly decreased in 3 patients (25%), and did not significantly change in the remaining 3 cases (25%). All patients with normalized aminotransferase values relapsed after ribavirin was discontinued and aminotransferase activity returned to pretreatment levels. Before therapy serum hepatitis C virus RNA was detected by polymerase chain reaction in 10 cases. None of them had cleared viral RNA when tested following 3, 6 and 9 months of ribavirin therapy. Side-effects were mild and reversible. In conclusion, about half of the patients with chronic hepatitis C who are unresponsive to alpha-interferon show a clear-cut biochemical response after 6-9 months of ribavirin administration. However, ribavirin does not clear circulating hepatitis C virus RNA and relapses occur after withdrawal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

N-acetyl cysteine enhances the response to interferon-alpha in chronic hepatitis C: a pilot study.

Hepatitis C virus (HCV) is an RNA virus that replicates in both the liver and lymphoid cells. Interferon-alpha (IFN-alpha) is a useful treatment of chronic hepatitis C (CHC) although resistance to this drug occurs frequently. The mechanisms underlying resistance to IFN remain unknown. In this work, we have measured the levels of glutathione in plasma and peripheral lymphoid cells from 15 healthy controls and 24 CHC patients, 10 of whom were without treatment and 14 showed high serum alanine aminotransferase (ALT) values despite therapy with lymphoblastoid IFN for more than 4 months. In all patients, glutathione levels in plasma and in mononuclear cells were depressed in comparison to controls. In IFN-unresponsive patients, the addition of 600 mg tid of oral N-acetyl cysteine (NAC), a glutathione precursor, resulted in a steady decrease of ALT values in all patients, with complete normalization in 41% of cases after 5-6 months of combined therapy. Administration of NAC alone for 1 month was without effect in the 10 patients that were not receiving IFN. Supplementation of IFN with NAC induced a near normalization of intralymphocytic glutathione, but plasma levels were only moderately increased. HCV replication was markedly inhibited in lymphocytes and viremia was cleared in one of the 8 patients tested. In conclusion, NAC enhances the response to IFN in CHC. Controlled studies are needed to ascertain whether antioxidant therapy might act in synergy with IFN in chronic viral hepatitis.

Acetylcysteine↗
PubMed1993

Experimental neurocytomas.

Four ethyl-nitrosourea (ENU)-induced oligodendroglioma-like tumors of the rat showing large rosettes on haematoxylin-eosin stain were studied by means of immunohistochemistry and electron microscopy, and their features compared with six human intraventricular neurocytomas. The similarities between the experimental and human tumors studied support the hypothesis that most of the so-called ENU-induced oligodendrogliomas in the rat are primitive neuroectodermal tumors with the tendency to differentiate toward a neuronal phenotype, and also suggest that the ENU-model of neurocarcinogenesis is useful for the induction of experimental neurocytomas.

Animals↗
PubMed1991

Soft selection and quantitative genetic variation: a laboratory experiment.

The effect of environmental heterogeneity on the genetic variation of different quantitative characters was studied in two laboratory and two recently captured populations of Drosophila melanogaster. Two different culture media (habitats R and G) were used. Coarse-grained heterogeneity with independent density control in each habitat (R + G), and fine-grained (R/G) heterogeneity were simulated in population cages. Control populations in both R and G habitats were also maintained. Genetic differences for oviposition-site preference, larval preference and/or within-habitat viability were found between subpopulations sampled from different media. This happened in all four populations maintained on R + G, two populations maintained on R/G, and one control population. Thus, environmental heterogeneity seems to protect genetic variability responsible for between-habitat genetic differentiation, particularly when such heterogeneity corresponds to the 'soft selection' model (R + G). However, for the quasi-neutral trait sternopleural bristle number, no genetic between-habitat differentiation, nor increased heritability were observed in populations maintained under any kind of environmental heterogeneity. Hence, although soft selection seems to be a real force in determining adaptation to heterogeneous environments, the genetic variability maintained may be small in relation to the whole genome.

Animals↗
PubMed1986

Characterization of surface roughness in titanium dental implants measured with scanning tunnelling microscopy at atmospheric pressure.

Characterization of the surface topography of implant materials is important for understanding tissue response. We have measured, for the first time, the topography of titanium surfaces used in osseointegrated dental implants. Scanning tunnelling microscopy (STM) which provides 3D real space images was used. In addition to clinical samples, electropolished and anodically oxidized surfaces were also measured. Clinical samples are rather inhomogeneous in character showing grooves and steps with a maximum depth of 0.11 micron. Micropores with an average diameter of about 30 nm are also present. Electropolished samples are rather homogeneous and very smooth, showing steps of 1 to 5 nm in height. The measurements were performed under atmospheric conditions at a resolution in the subnanometer range.

Dental Implantation, Endosseous↗
PubMed1984

General morphology and capsid fine structure of African swine fever virus particles.

The structure of African swine fever virus particles has been examined by electron microscopy. The analysis of virions prepared by negative staining, thin sectioning, and freeze-drying and shadowing showed that the virus particle was composed of several concentric structures with an overall icosahedral shape. The inner region of the virus particles was a nucleoid that was surrounded by a membrane covered by the capsid. The capsid had side-to-side dimensions of 172 to 191 nm and was built up by capsomers arranged in an hexagonal lattice. Computer-filtered electron micrographs of either negatively stained or freeze-dried and shadowed capsids revealed capsomers with a hexagonal outline and a hole in the center. The intercapsomer distance ranged from 7.4 to 8.1 nm. The triangulation number of the capsid was estimated to be 189 to 217, indicative of 1892 to 2172 capsomers. Extracellular African swine fever virus particles had an external membrane that resembled the cytoplasmic unit membrane.

African Swine Fever Virus↗
PubMed1984

CT findings in human fascioliasis.

Three patients with fascioliasis are presented in whom CT demonstrated abscesses and granulomas and permitted control of the disease's evolution after medical treatment.

Adult↗
PubMed1983

Structural localization of the proteins of the head to tail connecting region of bacteriophage phi 29.

The head to tail connector of bacteriophage phi 29 has been studied to locate its two structural proteins (p10 and p11). Treatment with trypsin led to proteolysis of p10 while p11 remained intact. Computer filtration of electron micrographs of crystals of trypsinized necks showed a change in the external 12-fold area of the neck when compared with control necks. Proteolized necks completely released p10 after treatment with low concentrations of an ionic detergent. The resulting structures, containing p11, showed similarity with the central area of the neck (seen in front view) and accounted for the lower collar and the axial extension of the neck (seen in side view). These results, together with the differences found in the proteolysis of p10 in necks with and without appendages, lead to a model for the neck region of phi 29 in which p10 makes the upper collar (and the external 12-fold area of the neck seen in front view), while p11 forms the lower collar and the axial extension (the inner region of the neck seen in front view).

Bacillus subtilis↗