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Biomedical subjects

S A Gomes

Publications and source records attributed to S A Gomes.

At least 19 recordsLinked to original sources
PubMed2006

Severe hyperkalemic type 4 renal tubular acidosis after kidney transplantation: a case report.

BACKGROUND: Hyperkalemia after transplantation is a common event, occurring in up to 70% of patients. It is usually asymptomatic but sometimes manifests as muscle weakness or cardiac arrhythmias. METHODS: Case report. RESULTS: At 102 days after a second cadaveric kidney transplantation, a 15-year-old boy, was admitted to the emergency room with severe muscle weakness. His examinations showed a serum potassium of 9.8 mEq/L; blood pH 7.1; serum bicarbonate 7.6 mmol/L; and creatinine 2.5 mg/dL. He was initially treated with sodium bicarbonate, calcium gluconate, and furosemide. Subsequent investigation showed hyperchloremic metabolic acidosis, urinary pH <5.5, positive urinary anion gap, reduced transtubular potassium gradient (TTKG, 1.5) and low levels of aldosterone (0.7 ng/mL), suggesting the presence of type 4 renal tubular acidosis (RTA). Other causes of hyperkalemia were excluded in the present case. Serum levels of potassium returned to normal when fludrocortisone was added to the bicarbonate supplementation. This case of severe hyperkalemic secondary to type 4 RTA after kidney transplantation only responded to the combination of alkali and mineralocorticoid therapies.

Acidosis, Renal Tubular↗
PubMed2004

Response to an oral calcium load in nephrolithiasis patients with fluctuating parathyroid hormone and ionized calcium levels.

The response to an oral calcium load test was assessed in 17 hypercalciuric nephrolithiasis patients who presented elevated parathyroid hormone (PTH) irrespective of the ionized calcium (sCa2+) levels. Blood samples were collected at baseline (0 min) and at 60 and 180 min after 1 g calcium load for serum PTH, total calcium, sCa2+, and 1.25(OH)2D3 determinations. According to the sCa2+ level at baseline, patients were classified as normocalcemic (N = 9) or hypercalcemic (N = 8). Six healthy subjects were also evaluated as controls. Bone mineral density was reduced in 14/17 patients. In the normocalcemic group, mean PTH levels at 0, 60 and 180 min (95 +/- 76, 56 +/- 40, 57 +/- 45 pg/ml, respectively) did not differ from the hypercalcemic group (130 +/- 75, 68 +/- 35, 80 +/- 33 pg/ml) but were significantly higher compared to healthy subjects despite a similar elevation in sCa2+ after 60 and 180 min vs baseline in all 3 groups. Mean total calcium and 1.25(OH)2D3 were similar in the 3 groups. Additionally, we observed that 5 of 9 normocalcemic patients presented a significantly higher concentration-time curve for serum PTH (AUC0',60',180') than the other 4 patients and the healthy subjects, suggesting a primary parathyroid dysfunction. These data suggest that the individual response to an oral calcium load test may be a valuable dynamic tool to disclose a subtle primary hyperparathyroidism in patients with high PTH and fluctuating sCa2+ levels, avoiding repeated measurements of both parameters.

Adult↗
PubMed2004

High proportion of subgroup A' (genotype A) among Brazilian isolates of Hepatitis B virus.

Hepatitis B virus (HBV) genotype A has been divided recently into two subgroups, designated A-A' (genotype A excluding A') and A'. Isolates belonging to subgroup A' have been identified in Africa. A new genotyping method, based on PCR amplification of the pre-S/S genome region and subsequent restriction fragment length polymorphism (RFLP) analysis, was developed, that established a correlation between RFLP subtypes and subgroups within genotype A. To investigate the occurrence of subgroup A' in South America, 119 Brazilian HBV isolates were analyzed. Ninety-three (78%) of them belonged to genotype A, with three predominating RFLP subtypes: 44 (37%) isolates were classified as AI, 30 (25%) were AII, and 18 (15%) were AIII. Pre-S/S nucleotide sequences of 15 genotype A isolates were determined. Phylogenetic analysis performed with these 15 and an additional 41 sequences revealed that isolates AI and AII clustered in subgroup A', whereas isolates AIII were classified into subgroup A-A'. The correlation RFLP subtypes-subgroups was confirmed by the presence of amino acid residues specific for subgroup A' in the surface antigens and polymerase of isolates AI and AII. The high proportion (63%) of isolates from subgroup A' suggested an African origin for a large number of Brazilian HBVs.

Amino Acids↗
PubMed2004

Uncommon mutation pattern of a hepatitis B virus isolate from genotype F infecting a patient with AIDS.

OBJECTIVE: To study the genomic variations of a hepatitis B virus (HBV) isolate in a patient coinfected with human immunodeficiency virus type 1 (HIV-1) who developed severe hepatitis and died of AIDS. METHODS: Two blood samples were collected, the first one during the asymptomatic phase of HIV-1 infection, and the other, 3 years later, few months before the death of the patient. Both samples were HBsAg and anti-HBe positive. Pre-S/S and precore-core genome regions were PCR amplified and analyzed. RESULTS: The HBV isolate belonged to genotype F, cluster IV. A number of unique amino acid substitutions were found in the surface antigen gene and the overlapping polymerase coding region of HBV genomes derived from both samples. However, these substitutions reflected natural variations rather than mutations of clinical significance. The precore stop codon mutation A(1896) was present in both genomes. Furthermore, the HBV genome derived from the second, but not first sample, showed two out-of-frame core interval deletions, one and 103 nucleotides in length, respectively. CONCLUSIONS: This is the first report of an HBV isolate from genotype F with core internal deletions. Our results suggest an association between specific core mutations and the severe hepatitis developed by the patient.

AIDS-Related Opportunistic Infections↗
PubMed2003

Frequent occult hepatitis B virus infection in patients infected with human immunodeficiency virus type 1.

The presence of hepatitis B virus (HBV) serological markers was investigated in 170 patients (137 male, 33 female) infected with human immunodeficiency virus (HIV) type 1. Antibodies to the hepatitis B core antigen (anti-HBc antibodies) were detected in 115 (68%) patients. Of these 115, 14 (12%) were hepatitis B surface antigen (HBsAg) positive, 60 (52%) presented anti-HBs antibodies, and 41 (35%) were anti-HBc positive only. All 115 of the anti-HBc positive samples were tested for HBV DNA by using two polymerase chain reaction (PCR) assays that amplify the core and pre-S regions of the HBV genome, respectively. HBV DNA was detected in 23 samples: 7 of 14 (50%) HBsAg-positive samples, 12 of 60 (20%) anti-HBs-positive samples, and 4 of 41 (10%) samples positive for anti-HBc only. Six samples (all HBsAg positive) were positive in both PCR assays and 17 samples were HBV DNA positive in only one assay. The mean viral load in HBsAg-positive patients was higher than that observed in HBsAg-negative patients. A number of patients were receiving treatment with lamivudine, a drug that interferes with both HBV and HIV replication. However, neither the rate of HBV DNA positivity nor HBV load was significantly different between patients treated with lamivudine and those not treated with this drug.

Adult↗
PubMed2003

Prevalence and genetic diversity of TT virus genotype 21 (YONBAN virus) in Brazil.

Isolates of the newly characterized, single-stranded DNA virus TTV, have been tentatively classified into four major phylogenetic groups and at least 28 genotypes. Four Japanese isolates, designated as YONBAN viruses, belong to the fourth group and to genotype 21. In this study, a genotype 21-specific PCR assay was standardized. With this assay, 48/184 (26%) serum samples and 76/167 (46%) saliva samples, collected from unselected ambulatory patients (aged 2 to 82) of a Brazilian public hospital, were positive. A total of 110 (66%) patients had TTV genotype 21 DNA in serum, saliva, or both fluids. Furthermore, 18/37 (49%) serum samples, collected from Indians belonging to three ethnic groups of the Western Brazilian Amazon, were also positive. Nucleotide sequences (253 bases at the 3' end of the non-coding region of the genome) were determined, that derived from 25 individuals, i.e. 17 patients and eight Indians. Phylogenetic analysis showed that three isolates from Indians of a particular ethnic group formed a separate subgroup within genotype 21. Among non-Indians, a clustering of strains was observed according to their country of origin (Japan or Brazil), with all 17 sequences derived from Brazilian patients located in a unique subgroup.

Adolescent↗
PubMed2001

Low frequency of mutations in the core promoter and precore regions of hepatitis B virus in anti-HBe positive Brazilian carriers.

BACKGROUND: Mutations in the core promoter and precore regions of the hepatitis B virus (HBV) genome, notably the double substitution (AGG to TGA) at nt positions 1762-1764 in the core promoter, and the precore stop codon mutation G to A at nt 1896, can often explain the anti-HBe phenotype in chronic carriers. However, the A1896 mutation is restricted to HBV isolates that have T at nt 1858. The double substitution at positions 1762-1764 has been described to occur preferentially in patients infected with strains showing C instead of T at nt 1858. RESULTS: HBV DNAs from 29 anti-HBe Brazilian samples were characterized by nucleotide sequencing of PCR products from precore region. Among them, 18 isolates presented C at nt 1858 (mostly genotype A strains). The 11 remaining isolates (genotypes D and F) had T1858. The stop codon mutation at nt 1896 was found in seven isolates (24% of the total and 63% of the isolates that had T1858). The frequency of the double substitution at positions 1762-1764 was surprisingly low (20%) among C1858 isolates. An association between A1896 and TGA 1762-1764 mutations was observed among genotype D isolates: these showed either none of the two mutations or both. Furthermore, strains mutated at positions 1896 and/or 1762-1764 also presented an elevated number of other, less common substitutions in the core promoter and precore regions. CONCLUSIONS: The data reported here are not in accordance with some reports from other parts of the world. In half of the isolates, none of the mutations previously described could explain the anti-HBe phenotype.

Brazil↗
PubMed2001

Role of superoxide and reactive nitrogen intermediates in Rhodnius prolixus (Reduviidae)/Trypanosoma rangeli interactions.

This study compares aspects of the superoxide, nitric oxide and prophenoloxidase pathways in Rhodnius prolixus hemolymph, measured in parallel, in response to Trypanosoma rangeli inoculation. Responses to two strains of T. rangeli, and two developmental forms, were studied, and the results obtained were correlated with the ability of the parasites to survive, multiply, and complete their life cycles in the hemolymph of the host. T. rangeli H14 strain parasites, which fail to complete their life cycle in Rhodnius by invading the salivary glands, stimulated high levels of superoxide and prophenoloxidase activity, which peaked 24 h after inoculation. Simultaneously, the concentration of hemolymph nitrites and nitrates increased, indicative of nitric oxide activity, but parasite numbers remained low. T. rangeli Choachi strain parasite inoculation also stimulated superoxide and prophenoloxidase activity, which, though significantly lower than the equivalent responses to the H14 strain, also peaked at 24 h. However, nitrate and nitrite levels in Choachi strain-inoculated hemolymph remained low, and this parasite strain multiplied rapidly, especially following peak superoxide activity, and eventually invaded the salivary glands for transmission to a vertebrate host. In both strains, short form epimastigotes stimulated greater superoxide and prophenoloxidase responses than long form epimastigotes. Injection of the NADPH oxidase inhibitor N-ethylmaleimide or the inducible nitric oxide synthase inhibitor S-methyl isothiourea sulfate caused significantly higher insect mortalities in groups of R. prolixus inoculated with either parasite strain compared with those of uninfected control insects. This indicates that both NADPH oxidase and nitric oxide synthase activity may be involved in the immune response of R. prolixus to infection by T. rangeli. Finally, Western blotting of R. prolixus hemocyte lysates revealed the presence of a protein immunologically related to the human NADPH oxidase complex, the initiator enzyme of the respiratory burst.

Animals↗
PubMed2000

Nosocomial spread of hepatitis B virus in two hemodialysis units, investigated by restriction fragment length polymorphism analysis.

A method for genotyping hepatitis B virus (HBV) strains, based on restriction fragment length polymorphism (RFLP) analysis of four different amplified fragments of the HBV genome, was used to investigate nosocomial infections that occurred in two Brazilian hemodialysis centers. Viral isolates from hepatitis B surface antigen (HBsAg)-positive serum samples from 27 hemodialysis patients and 39 HBV-positive unrelated control patients were grouped according to their RFLP patterns. Strains isolated from the control patients were divided into nine RFLP patterns: A1, A2, A3 (genotype A), D1, D2, D3, D4 (genotype D), F1, and F2 (genotype F). In hemodialysis unit A (Rio de Janeiro), 14 HBV isolates were grouped into five different RFLP patterns: A1, A2, A3, D3, and D4. Pattern A2, present at a relatively low prevalence (18%) in the control group, was observed in the majority (53%) of the hemodialysis patients. Notably, all five patients who seroconverted to HBsAg positivity in 1995 carried the strain A2. In hemodialysis unit B (state of São Paulo), where an outbreak of HBV infection occurred in 1996-1997, RFLP analysis showed that all 13 patients who seroconverted were infected with HBV isolates of genotype D. Coinfection with strain A1 was detected in seven of them. The results demonstrate the value of RFLP analysis in establishing common sources of infection in hemodialysis centers.

Cross Infection↗
PubMed1999

Age-specific prevalence and transmission of TT virus.

TT virus (TTV) is an unenveloped, single-stranded DNA virus that was discovered recently in the sera of Japanese patients with posttransfusion hepatitis of unknown etiology. A high prevalence of TTV infection in blood donors of several countries, including Brazil, has been demonstrated. To study the variation in TTV prevalence between different age groups, sera from 223 individuals without liver disease, aged 0-80 years, were tested by the polymerase chain reaction for the presence of TTV DNA. All subjects were inhabitants of the city of Rio de Janeiro, Brazil. The prevalence increased continuously with age (P <.001), from 17% among children under the age of 11 years, to 57% in people older than 50 years. To assess vertical transmission, sera from 105 unselected, consecutive parturient women attending a public maternity hospital were paired with cord bloods and examined for the presence of TTV DNA. Thirty-seven (35%) mothers were found to be TTV infected. Seven cord bloods were also positive, suggesting the possible transplacental transmission of the virus. Furthermore, a direct correlation between TTV viremia and presence of antibodies to the enterically transmissible hepatitis A virus (HAV) was observed in this group of women, with a relative risk of TTV infection of 5.09 (95% confidence interval 0.76-34.03) for women with anti-HAV, compared with women without. This finding suggested that the fecal-oral route might be an important route of TTV transmission.

Adolescent↗
PubMed1999

Rhodnius prolixus infected with Trypanosoma rangeli: In vivo and in vitro experiments.

Studies were carried out on the activation of the prophenoloxidase (proPO) in adults of Rhodnius prolixus infected by short and long epimastigote forms of Trypanosoma rangeli. The in vitro activation of the proPO cascade using l-DOPA as substrate was very low in the absence of fat body extract, hemolymph, and parasites. On the other hand, a higher PO activity was observed when short, but not long, epimastigotes of T. rangeli were incubated with fresh hemolymph, fat body extract, and l-DOPA. Supernatant from lysed long epimastigotes increased the PO activity at levels identical to those observed with supernatants from lysed short epimastigotes. Similarly, the PO activity of hemolymph obtained from inoculated insects with long epimastigotes of T. rangeli showed a very low activity when incubated with l-DOPA compared to the PO activity of hemolymph taken from insects inoculated with short epimastigotes of T. rangeli. Control insects inoculated with sterile PBS showed no PO activity. These data indicate the presence of (a) factor(s) in the hemolymph as well as in the fat body extract that may be released (or induced) by the presence of short epimastigotes of T. rangeli and which results in the activation of the R. prolixus proPO system. The implications of these findings are discussed in relation to the development of T. rangeli and its ability to overcome the proPO system, survive, and successfully colonize the hemolymph of R. prolixus.

Animals↗
PubMed1999

A polymerase chain reaction-based assay to identify genotype F of hepatitis B virus.

We have developed a polymerase chain reaction (PCR) assay which distinguishes genotype F from the other genotypes of hepatitis B virus (HBV). The method was used to characterize HBV strains isolated in urban areas of the Brazilian Amazon. DNA was amplified in 54 of a total of 78 HBsAg-positive serum samples, using universal, non-genotype-specific primers. Only 4 (7.4%) were identified as genotype F by our genotype-specific PCR assay. This proportion is notably lower than that previously reported in Argentina, Venezuela, Peru, and Central America.

Amino Acid Sequence↗
PubMed1999

High prevalence of TT virus infection in Brazilian blood donors.

A recent report has described the molecular cloning and characterization of a novel, single-stranded DNA virus, named TT virus (TTV), which was present in the sera of Japanese patients with posttransfusion hepatitis of unknown etiology [Okamoto et al. (1998) Hepatology Research 10:1-16]. Using a nested polymerase chain reaction assay, sera from Brazilian patients with acute non A-C hepatitis and blood donors were examined for the presence of TTV DNA sequences. Thirty-seven of 52 (71%) patients with acute non A-C hepatitis and 45 of 72 (62%) blood donors were found to have TTV sequences in their sera. Such a high proportion in blood donors indicated that TTV infection is common in the general Brazilian population. Partial nucleotide sequences (326 bases in open reading frame 1) from seven isolates were determined. By phylogenetic analysis, four TTV strains were classified into the genomic subgroup G1a described previously. The three others belonged to subgroup G1b. Sequence homologies between strains belonging to a same subgroup were 92.9-99.1%, whereas homologies of 85.9-90.2% were calculated between isolates from different subgroups.

Adolescent↗
PubMed1998

Genomic variations of hepatitis B virus strains in patients chronically coinfected with hepatitis B and human immunodeficiency viruses.

Serum samples from 56 human immunodeficiency virus type 1 (HIV-1)-infected adult men were analysed for the presence of hepatitis B virus (HBV) serological markers. Two or more samples from each patient, collected over an interval of 1-6 years, were tested. The antibody against HBV core antigen (anti-HBc) prevalence was 79%. Three (5%) patients No. 5, 7, and 9 were chronic carriers of HBV surface antigen (HBsAg). HBV DNAs from serial samples of these three patients and from two HIV-seronegative control patients were characterised after amplification of different genome regions by polymerase chain reaction (PCR). Size and restriction analyses of the PCR products showed that samples from patients No. 7 (with chronic active hepatitis) and 9 (asymptomatic) contained heterogeneous HBV DNA populations. In patient No. 7, HBV DNA contained a precore gene stop codon mutation at nucleotide (nt) 1896. In addition, a deletion in the core gene was found in a sample collected two years after the onset of acquired immunodeficiency syndrome (AIDS). PCR products from serial samples of patient No. 9 indicated a mixture of HBV DNA molecules that were cloned. Sequencing of the pre-S region of the clones and phylogenetic analysis showed that patient No. 9 was superinfected with three HBV populations of distinct origin, all belonging to genotype A. HBV DNA of patient No. 5 (with AIDS) did not present any variability during a 6-year follow-up. Although two of three HIV/HBV coinfected patients harboured heterogeneous HBV DNA populations during the follow-up, no common event with respect to HBV DNA evolution was observed among the coinfected patients.

AIDS-Related Opportunistic Infections↗
PubMed1996

Sequence analysis of pre-S/S gene of hepatitis B virus strains of genotypes A, D, and F isolated in Brazil.

The nucleotide sequences of pre-S/S gene of nine hepatitis B virus strains (3 adw2, 3 ayw2, and 3 ayw 3) and of pre-S region of two adw4 isolates from Rio de Janeiro, Brazil, were determined. Phylogenetic analysis allowed to classify these strains into three genotypes, A, D and F, reflecting the diverse origin of the population. However, strains belonging to a same genotype were separated by a short evolutionary distance. The presence of aminoacid mutations into Pre-S region not found in hepatitis B viruses isolated in other parts of the world is described.

Amino Acid Sequence↗
PubMed1996

Detection of hepatitis B virus DNA in hepatitis B surface antigen-negative serum by polymerase chain reaction: evaluation of different primer pairs and conditions.

The presence of hepatitis B virus (HBV) DNA was investigated by polymerase chain reaction (PCR) in the serum of twenty Brazilian blood donors. All sera were negative for hepatitis B surface antigen (HBsAg), 17 of them presented antibodies to the hepatitis B core antigen (anti-HBc) as the unique serological marker of HBV infection, and 3 were positive for antibodies to HBsAg (anti-HBs) and anti-HBc. PCR assays were carried out using different pairs of oligonucleotides designed from conserved sequences of C, pre-S and S regions of the HBV genome. First, all oligonucleotide pairs were tested in PCR using plasmids carrying HBV genome from ayw or adw strains as templates. One-round PCR assays were able to detect 100-25,000 molecules of plasmid DNA, depending on the oligonucleotide pair, while semi-nested PCR assays detected 10-1000 molecules. The frequency of HBV DNA-positive results with HBsAg-sera varied from 0% to 50% depending upon the PCR assay. The results indicated that a number of both isolated anti-HBc and anti-HBs+, anti-HBc+ samples contained HBV DNA at a very low concentration, neighboring the limit of detection.

DNA Primers↗
PubMed1995

Adenovirus genome types isolated from stools of children with gastroenteritis in São Paulo, Brazil.

In a prospective one-year study of acute gastroenteritis in hospitalized children less than 2 years of age, in São Paulo (Brazil), adenoviruses were detected by specific enzyme immunoassay (El-ARA) in 7 of 67 (10%) ill children and in 9 of 79 (11.4%) controls. They were the sole recognizable agent of diarrhea in 6 ill children. In another child these viruses were detected in a dual infection with astrovirus. Enteric adenoviruses (Ad40/41) were the most common serotypes detected in children with diarrhea (3/7) and Ad7 the serotype most detected in the controls (5/9), associated with lower respiratory tract infection. Thirteen adenovirus strains, isolated in HEp2 or HEK-293 cells, were characterized by seroneutralization and restriction enzyme analysis. The established adenoviruses were typed as AV-7-D5 (five associated to lower respiratory tract infection and one to diarrhea), AV-1-D10 (one diarrhea case), AV-31-D2 (two controls with respiratory infection), and two isolates as AV-12-D7, a new genome type. One subgenus D isolate, serotype 28, with restriction patterns different from those of the prototype, remained untyped. Only one enteric adenovirus could be typed. The restriction patterns of this isolated were similar to those of the prototype AV-41-D1. The genome type of the other three enteric adenoviruses could not be determined.

Acute Disease↗