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Biomedical subjects

R Esteban

Publications and source records attributed to R Esteban.

At least 163 records · Page 9Linked to original sources
PubMed1988

Chronic hepatitis D in intravenous drug addicts and non-addicts. A comparative clinico-pathological study.

In recent years chronic infection by the hepatitis delta virus (HDV) has become an important cause of chronic liver disease among drug addicts. To evaluate the influence of addiction to i.v. drugs on the course of this disease we have analyzed the clinical, histopathological, virological and evolutive features in 18 addicts and 11 non-addicts with chronic delta infection. Recent acute hepatitis D, documented as HDV superinfection, was observed in 14 addicts (77%) and in 2 non-addicts (18%) (P less than 0.02). At the time of evaluation for chronic liver disease, the frequency of symptoms, the degree of biochemical disturbances and the histopathological severity were similar in the two groups but the duration of HDV infection was probably shorter in drug addicts. HBV replication, as indicated by the presence of HBeAg and HBV-DNA in serum and HBcAg in liver, was more frequent in addicts. The amount of HDAg in liver tissue was also greater in addicts (P less than 0.005). Antibodies against the human immunodeficiency virus were detected in all of the addicts (P less than 0.001). Although most patients remained asymptomatic, significant histological worsening occurred in one half of the cases after a relatively short period of follow-up (25.1 +/- 16.3 months). The tendency to deteriorate in addicts (61% of cases) was greater than in non-addicts (36%). These observations suggest that the prognosis of chronic HDV infection is particularly poor in drug addicts in whom rapid deterioration may be related to simultaneous and inadequately controlled replication of hepatotropic viruses.

Chronic Disease↗
PubMed1988

Site-specific binding of viral plus single-stranded RNA to replicase-containing open virus-like particles of yeast.

X double-stranded RNA is a deletion mutant of L-A double-stranded RNA and is encapsidated in viral particles by the L-A-encoded major coat protein. X double-stranded RNA has all the cis sites necessary to be transcribed, encapsidated, and replicated. We have cloned X double-stranded RNA and sequenced it. The complete X double-stranded RNA sequence deduced indicates that the first 25 bases of the X plus-strand 5' end originated from the 5' end of the L-A plus strand and that most, if not all, of the rest comes from the 3' end of the L-A plus strand. The X plus strand made by X double-stranded RNA-containing virus-like particles binds specifically to empty open virus-like particles and is converted by these particles to X double-stranded RNA. RNA transcripts of the X complementary DNA clones and deletion derivatives thereof were made in vitro by T7 and T3 RNA polymerases and tested for specific binding to the virus-like particles. The results suggest that the binding is due to the sequence UUUGGCCAGG, 370 bases upstream from the X plus-strand 3' end. This sequence is also present in the M1 plus strand 140 bases from its 3' end.

Amino Acid Sequence↗
PubMed1988

A deletion mutant of L-A double-stranded RNA replicates like M1 double-stranded RNA.

X double-stranded RNA (dsRNA) is a 0.52-kilobase dsRNA molecule that arose spontaneously in a nonkiller strain of Saccharomyces cerevisiae originally containing L-A and L-BC dsRNAs (L-BC is the same size as L-A but shares no homology with it). X hybridized with L-A, and direct RNA sequencing of X showed that the first 5' 25 base pairs (of the X positive strand) and at least the last 110 base pairs of the 3' end were identical to the ends of L-A dsRNA. X showed cytoplasmic inheritance and, like M1, was dependent on L-A for its maintenance. X was encapsidated in viruslike particles whose major coat protein was provided by L-A (as is true for M1), and X was found in viruslike particles with one to eight X molecules per particle. This finding confirms our "head-full replication" model originally proposed for M1 and M2. Like M1 or M2, X lowers the copy number of L-A, especially in a ski host. Surprisingly, X requires many chromosomal MAK genes that are necessary for M1 but not for L-A.

Base Sequence↗
PubMed1987

Anti-HD IgM as a marker of chronic delta infection.

The value of anti-HD IgM as a marker of chronic delta infection was evaluated by correlating its presence in serum with that of HD-Ag in liver cells and with the degree of inflammatory activity. Thirty-six patients with HBsAg-positive chronic hepatitis and anti-HD at high titers were studied. Overall, the liver cells of 26 patients contained HD-Ag and 27 were positive for IgM anti-HD. The correlation between both markers was excellent: 25 cases were positive for both serum anti-HD IgM and intrahepatic HD-Ag and 8 were negative for both markers. There was only 1 HD-Ag-positive patient, who was anti-HD IgM-negative. Two patients were anti-HD IgM-positive and HD-Ag-negative. Histological damage was more severe in anti-HD IgM-positive cases than in those negative for this marker (Knodell's index 13.5 vs 11.9, P less than 0.01). We conclude that anti-HD IgM is a good marker of chronic active delta infection.

Adolescent↗
PubMed1987

A new non-mendelian genetic element of yeast that increases cytopathology produced by M1 double-stranded RNA in ski strains.

The Saccharomyces cerevisiae SKI (superkiller) genes are repressors of replication of M, L-A, and L-BC double-stranded (ds) RNAs; ski strains have an increased M dsRNA copy number and, as a result, are cold-sensitive for growth at 8 degrees. Growth is normal, however, at higher temperatures. We have found a new cytoplasmic genetic element [D] (for disease) that makes M1 dsRNA-containing superkiller strains grow slowly at 30 degrees, not at all at 37 degrees, and only very poorly at 20 degrees. These growth defects require three factors: a chromosomal ski mutation, the presence of M1 dsRNA, and the presence of the new cytoplasmic factor, [D]. We have isolated mutants unable to maintain [D] (mad), at least one of which is due to mutation of a single chromosomal locus. Further, [D] can be cured by growth at 37-39 degrees. We present evidence that [D] is not M, L-A, L-BC or W dsRNAs or mitochondrial DNA, 2 mu DNA, or [psi], but [D] depends on L-A for its maintenance. We also show that [D] is distinct from [B], a cytoplasmic element that allows M1 dsRNA to be stably replicated and maintained in spite of defects in certain chromosomal MAK genes that would otherwise be necessary. [D] activity is blocked by the presence of another extrachromosomal element, called [DIN] (for [D] interference). [D] and [DIN] may be different natural variants of the same molecule.

Genes, Fungal↗