Biomedical subjects

S A Gomes

Publications and source records attributed to S A Gomes.

32 records · Page 2Linked to original sources

PubMed1994

Genetic diversity of hepatitis B virus strains isolated in Rio de Janeiro, Brazil.

Hepatitis B virus (HBV) genomes have been classified into six groups, A-F, group F being the most divergent. South America has provided the smallest number of strains studied at the genome level. The only HBV strain from this region sequenced completely has been classified in group F, and contains the most divergent of the HBV genomes presently known [Naumann et al. (1983): Journal of General Virology 74:1627-1632]. To evaluate genetic relatedness between strains isolated in South America and in the rest of the world, a restriction endonuclease analysis was carried out on 14 HBV strains (4 adw2, 3 adw4, 3 ayw2, and 4 ayw3) isolated in Rio de Janeiro, Brazil. C, pre-S, and X genes along with the 5' part of the P gene from these strains were amplified by the polymerase chain reaction. The DNA fragments were digested by BamHI, BstEII, EcoRI, HhaI, and TaqI endonucleases. The restriction patterns obtained were compared with those deduced from the nucleotide sequence of 26 HBV strains isolated in other continents. The results showed a large genetic variability of Brazilian strains. Taking into account that all the samples examined possessed the w antigenic subdeterminant, the number of different restriction patterns of strains isolated in Rio de Janeiro was at least as large as that of the reference strains isolated in the rest of the world. Some original restriction patterns were found in adw4 and ayw2 HBV strains.

Base Sequence↗

PubMed1992

Growth of fastidious adenovirus serotype 40 in HRT 18 cells: interactions with E1A and E1B deletion mutants of subgenus C adenoviruses.

Growth of fastidious adenovirus serotype 40 (Ad40) in several cell lines was investigated. Ad40 was able to readily propagate in human intestinal cell line, HRT 18. Coinfection assays were made in non-permissive and permissive cells between Ad40 and Ad5dl312 or dl1520, mutants deleted in E1A and E1B regions, respectively, to test the ability of Ad40 to complement these mutants and vice versa. Ad40 could enhance Ad5dl312 DNA synthesis in HRT18 and HeLa cells, although its own DNA disappeared in the presence of this mutant in HRT18 cells. In coinfection with dl1520, Ad40 DNA synthesis was inhibited by dl1520 in HRT18 cells and dl1520 DNA synthesis was inhibited by Ad40 in 293 cells. This might reflect the presence of unusual products encoded by Ad40 E1B region.

Adenovirus Early Proteins↗

PubMed1992

Histopathological evidence of protective action of garlic against collagen and arachidonic acid toxicity in rabbits.

Soluble rat tail tendon collagen produced respiratory distress, agitation, convulsions and finally death in rabbits when infused intravenously (i.v.) in lethal doses. Similar observations were noted when a lethal dose of arachidonic acid (unsaturated essential fatty acid) was infused. These agents caused thrombocytopenia, indicative of in vivo platelet aggregation, hypotension and increased levels of thromboxane (TX) B2 (a stable metabolite of TXA2) in the plasma. Histopathological examination of lung, heart and liver tissue indicated that the lungs and livers of treated animals were adversely affected, while heart tissues appeared to be normal. Histopathological examination of lung and liver tissues of animals pretreated with garlic, then treated with a lethal dose of collagen or arachidonic acid showed a significant reduction in the damage observed compared to animals not pretreated with garlic.

Animals↗

PubMed1991

Restriction site mapping of four genome types of adenovirus types 3 and 7 isolated in South America.

New genome types of Ad3 and Ad7 were found among adenovirus (Ad) strains isolated from stools of children during epidemiological surveys made in São Paulo, Brazil, and Buenos Aires, Argentina. These were characterized by DNA analysis with 11 restriction endonucleases and showed a number of new restriction patterns, notably for BamHI, BcII, BgIII, HindIII, KpnI, and SmaI. Restriction maps of the genome types, named Ad3e1, Ad3e2, Ad3h, and Ad7h, were constructed and compared with those of Ad3p and Ad7p.

Adenoviruses, Human↗

PubMed1991

Cellular transformation by E1 genes of enteric adenoviruses.

The ability of Ad40 and Ad41 E1A plus E1B genes to transform BRK cells was considerably lower than that of Ad5 and Ad12 corresponding genes. However, as for Ad5, the E1A genes of enteric adenoviruses could cooperate with an activated ras oncogene for full cell transformation and the Ad41 E1B could be complemented by E1A gene of Ad5 or Ad12 for cell transformation. Complementation studies suggested that the conserved region 1 of Ad41 E1A was responsible for this inefficient transformation. The Ad40- and Ad41-transformed cell lines exhibited a low level of major histocompatibility complex (MHC) class I antigens correlated to the low level of Ad12-transformed cells. Class I MHC antigen amounts expressed at the surface of the cells transformed by the weakly oncogenic Ad3 were between the high level of Ad5- and the low level of Ad12-transformed cells.

Adenovirus Early Proteins↗

PubMed1991

Collagen toxicity in rabbits.

Different preparations of soluble collagen, from rabbit skin, rat skin, rat tail tendon and guinea-pig skin, produced respiratory distress, agitation, convulsions and finally death when infused intravenously in lethal doses. Analysis of plasma enzyme levels indicated significant increases in total, cardiac and hepatic lactate dehydrogenase, suggesting that damage to the liver occurred as a result of collagen infusion. Histopathological examination of lungs, livers and hearts of collagen-treated rabbits confirmed that damage had occurred to the lungs and livers of these animals, while heart tissues appeared to be normal. The source of collagen did not appear to influence its toxicity at the tissue level.

Alanine Transaminase↗

PubMed1990

Antithrombotic activity of garlic: its inhibition of the synthesis of thromboxane-B2 during infusion of arachidonic acid and collagen in rabbits.

Rabbits were given collagen and arachidonic acid intravenously. Blood pressure, platelet counts, plasma thromboxane-B2 (TXB2) and plasma 6-keto-prostaglandin F1 alpha, (6-keto-PGF1 alpha) were determined. Both thrombogenic agents, upon infusion of a lethal dose, caused thrombocytopenia, indicative of in vivo platelet aggregation and hypotension. These changes were associated with an increase in plasma levels of TXB2 and 6-keto-PGF1 alpha measured by radioimmunoassay (RIA). Pretreatment of rabbits with an aqueous extract of garlic (500 mgkg) provided protection from thrombocytopenia and hypotension. Thromboxane-B2 synthesis was significantly reduced in animals pretreated with garlic and then injected with a lethal dose of either collagen or arachidonic acid. The amount of TXB2 synthesized in these animals was not sufficient to induce thrombocytopenia or hypotension. All animals pretreated with garlic were well protected against the effects of collagen or arachidonate infusion, and no apparent symptoms were observed in these animals. These observations indicate that garlic may be beneficial in the prevention of thrombosis.

6-Ketoprostaglandin F1 alpha↗

PubMed1989

New genome types of adenovirus types 1, 3, and 5 isolated from stools of children in Brazil.

During an epidemiological survey made in São Paulo (Brazil), fecal specimens were periodically collected from 100 randomly chosen babies from birth to the age of 18 months. The stools, routinely collected each month and also collected each time a child presented any sign of disease, were screened for the presence of adenoviruses. Sixteen adenovirus strains, isolated from the stools of healthy and ill children, were characterized by restriction enzyme analysis. Five isolates were from subgenus A, five were from subgenus B, four were from subgenus C, and two were from subgenus D. All but two showed some restriction patterns different from those of the 42 human adenovirus prototypes and all the genome types described up to now. No fastidious adenovirus (subgenus F, serotypes 40 and 41) was encountered in the stools examined. We report here the restriction enzyme analysis of isolates of subgenera B and C. The following new designation genome types are proposed: Ad3e1 (subgenus B) and Ad1d, Ad5a1, and Ad5a2 (subgenus C).

Adenoviridae Infections↗

PubMed1989

Dynamics of corneal epithelial healing after an alkali burn. A statistical analysis.

A precise definition of epithelial healing kinetics following chemical injury is necessary to aid the investigation of control mechanisms, potential therapeutic intervention and ophthalmic drug toxicity. Wound healing was studied photographically at frequent intervals in rabbits following 1N or 4N alkali burns. Planar wound areas were determined by computerized planimetry and transformed mathematically to curved surface data. The decrease in equivalent wound radius with time was computer-modelled using two linear and three nonlinear regressions. A periodic function was also investigated. Serial photographs showed that intermittent attrition of small areas of the migrating wound edge was a common confounding variable. Although excellent coefficients of determination were found for all models, the addition of nonlinear factors gave a small advantage. A mean lag phase of 3.96 and 6.52 hr occurred after 1N and 4N alkali burns, respectively; wound edge attrition was notably prevalent in early healing. Epithelial healing in the rabbit had a fundamental linear component, with mean epithelial migration rates of 76 and 80 microns/hr after 1N and 4N alkali burns, respectively, and which continued to closure. A quadratic nonlinear component was also suggested. No significant circadian component was detected.

Alkalies↗

PubMed1988

Genome analysis of adenovirus 4a, a causative agent of pharyngoconjunctival fever and respiratory diseases in Brazil.

An outbreak of pharyngoconjunctival fever caused by adenovirus (Ad) occurred in 1976 in Belem (northern Brazil). By restriction endonuclease analysis, it was shown that the type responsible was Ad4a, a variant of Ad4 prototype (Ad4p) and previously described as causative agent of ocular diseases. In an epidemiologic study carried out in Rio de Janeiro and Belem between 1977 and 1986, 148 Ads were isolated from children with respiratory disease. All five Ad4 strains encountered during this study were also Ad4a. This type, circulating in South America, can therefore cause both ocular and respiratory diseases. No Ad4p was isolated during this study. A percent of comigrating restriction fragments of only 50% between Ad4p and Ad4a was calculated from 13 restriction enzyme patterns. The restriction maps of Ad4a for nine endonucleases are presented and compared with those of Ad4p.

Adenoviridae↗

PubMed1987

Human adenovirus from subgenus D: restriction mapping of types 9 and 19 and characterization of a new genome type.

A strain of adenovirus (AV) was isolated from the stools of a child with acute gastroenteritis. This virus (strain 208) was specifically neutralized by antiserum to AV19, a species belonging to subgenus D and previously reported to cause keratoconjunctivitis. However, restriction analysis of strain 208 showed it to be distinct from AV19 and the other 40 human AV serotypes presently known. When calculated from 18 restriction patterns, the proportion of comigrating fragments common to AV19 and strain 208 was only 57%. This percentage was no higher than that obtained by comparison of strain 208 and AV9, a randomly chosen type from subgenus D. Strain 208 therefore appeared to represent a new genome type. The restriction maps of the three viruses for BamHI, ClaI, EcoRI, HindIII, MluI, NdeI and SfiI endonucleases are presented.

Adenoviruses, Human↗

PubMed1986

Direct detection and differentiation of fastidious and nonfastidious adenoviruses in stools by using a specific nonradioactive probe.

Restriction fragments of fastidious human adenovirus type 41 (Ad41) were cloned in vector plasmid pBR322. A rapid and sensitive nonradioactive molecular-hybridization technique (M. Renz and C. Kurz, Nucleic Acids Res. 12:3435-3444, 1984) showed that one clone specifically detected fastidious Ad40 and Ad41 (subgenus F) without cross-hybridization with nonfastidious adenoviruses. This clone was mapped in a region of the Ad41 genome corresponding to early transcription unit E1B of Ad2. A number of DNAs from fastidious and nonfastidious adenoviruses were extracted, without cultivation, from stools of children with gastroenteritis and were hybridized with an Ad2 probe and with the cloned probe, allowing the differentiation of the two groups of viruses. This method could detect DNA quantities as low as 10 pg and should be particularly suitable for stool samples containing adenoviral DNA in amounts too low to be detected by staining with ethidium bromide.

Adenovirus Infections, Human↗

PubMed1985

In situ hybridization with biotinylated DNA probes: a rapid diagnostic test for adenovirus upper respiratory infections.

Adenovirus DNA was detected in cells from nasopharyngeal secretions of children with acute respiratory infections by in situ hybridization with biotinylated probes. The technique was easy to perform, giving rapid results which were well correlated with those of immunofluorescence assays of the same samples. Adenoviruses of subgroups B, C and E were detected equally well by probes prepared either from purified adenovirus type 5 or from a plasmid (A1) carrying a cloned insertion of BamH1 fragments C and D of adenovirus type 2 in pAT 153. The use of stable non-radioactive probes makes in situ hybridization a feasible assay for use in clinical laboratories with moderate resources.

Adenoviridae Infections↗

PubMedDate not supplied

Western blot analysis of the reactivity between envelope proteins of hepatitis B viruses from Brazilian carriers and antibodies raised against recombinant hepatitis B vaccines.

A Western blot assay was standardized to evaluate the antigenic reactivity of hepatitis B virus (HBV) strains circulating in Brazilian population with antibodies raised against recombinant hepatitis B (HB) vaccines. In this assay, HBV envelope proteins from infected human blood were detected by antibodies from rabbits immunized with either of two recombinant vaccines. These were Engerix B (Smith Kline Beecham, Belgium) containing exclusively S protein particles and TGP-943 (Takeda Chemical Industries, Japan) containing M protein particles. Forty-seven serum samples, presenting HB surface antigen. (HBsAg) reverse passive haemagglutination assay (RPHA) titers ranging from 1:32 to > or =1:4096 after HBV particles concentration, were tested. Twenty-seven samples were from acute hepatitis cases and 20 were from chronic cases (11 from cirrhotic patients and 9 from asymptomatic carriers). Four HBV serotypes, adw2, adw4, ayw2 and ayw3, were identified in these samples. Infectivity of these sera was evaluated by HBV DNA detection by polymerase chain reaction (PCR). HBV DNA was present in 62% of samples from acute cases and in all samples from chronic cases. Despite the differences between serotypes, genotypes, forms of infection, and infectivity of the samples, antibodies against both vaccines reacted with HBV envelope proteins from all but one sample. In one sample from cirrhotic patient, only a small protein of unexpected size reacted with TGP-943 antibodies.

Acute Disease↗