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Biomedical subjects

V Gomes

Publications and source records attributed to V Gomes.

16 recordsLinked to original sources
PubMed2026

Mitochondrial DNA diversity in Ecuadorian populations: Recurrence of variant 16136 within haplogroup B2.

The identification of lineage-defining variants, frequently found in the coding region of mitochondrial DNA (mtDNA), is essential for refining haplogroup classification. Most mtDNA studies in South American populations have focused on the control region (CR), which has provided important insights into population structure and maternal lineage origins, although information needed for more robust phylogenetic resolution has been neglected. This study investigates the maternal genetic structure of Ecuadorian populations by combining CR and whole mitogenome analyses. Sequences from the mtDNA CR were obtained from 461 individuals (253 Mestizos and 208 Native Americans), while complete mitogenomes were sequenced for 127 individuals to improve phylogenetic resolution by identifying lineage-defining variants present in coding region. Most mtDNA haplogroups in the two population groups analyzed were of Native American origin (A2, B2, B4, C1, D1, D4), with significant differences in the distribution of specific lineages between them. Among Mestizos, African haplogroups (all within the L branches) and Eurasian haplogroups (H, K, R, U) were detected at low frequencies, whereas no African lineages were observed among Native Americans. The results obtained highlighted a heterogeneity within Ecuadorian populations that must be considered when developing mtDNA haplotype databases for forensic purposes. Whole mitogenome sequences enabled the identification of variants that refined haplogroup classifications, provided a more accurate reconstruction of the maternal genetic diversity, and improve the discrimination between Native American and Asian maternal lineages within haplogroup B4b.

Humans↗
PubMed1995

[Multiple endocrine neoplasia type IIb].

We describe the clinical manifestations of a multiple endocrine neoplasia, type IIb, in a 32 year old woman, admitted to a general hospital with intestinal sub-occlusion. The phenotype associated with bilateral pheochromocytomas show us the diagnosis, but the unsolved problem is the high levels of calcitonin, without macroscopic evidence of tumor relapse.

Adult↗
PubMed1994

Nodular regenerative hyperplasia of the liver: ultrasonographic appearance and echo-guided bioptic diagnosis.

Nodular regenerative hyperplasia of the liver is characterized by multiple and usually small nodules of hyperplastic hepatocytes surrounded by compressed atrophic liver cells. Given the small size of nodules and the preserved framework, the imaging techniques often show a normal liver and blind percutaneous biopsy is misinterpreted. The Authors report two cases of nodular regenerative hyperplasia diagnosed by ultrasound and percutaneous echoguided biopsy.

Biopsy, Needle↗
PubMed1994

Ultrasound-guided fine-needle biopsy of hepatocellular carcinoma: comparison between smear cytology and microhistology.

OBJECTIVES: The aims of this study were to evaluate the typing accuracy of smear cytology and microhistology and of their association in the diagnosis of hepatocellular carcinoma arising in liver cirrhosis, and to analyze the usefulness of smear cytology in the diagnosis of well-differentiated neoplasms. METHODS: One hundred sixty patients with hepatocellular carcinoma underwent an ultrasound-guided fine-needle biopsy, providing material for cytological and histological study. In 73 patients, a double biopsy with noncutting and cutting needles was performed (double-needle group), whereas in the remaining 87, a single biopsy with cutting needle was carried out (single-needle group). RESULTS: In the whole population examined, smear cytology, microhistology, and their association, provided the diagnosis of hepatocellular carcinoma in 128 (80%), 98 (61%), and 144 (90%) cases, respectively. The double-needle and the single-needle groups did not differ significantly as to typing accuracy. Smear cytology correctly diagnosed 54 of 64 neoplasms classified histologically as well-differentiated. CONCLUSIONS: Our results show that both smear cytology and microhistology should be applied immediately, when diagnosing hepatocellular carcinoma arising in liver cirrhosis, and that smear cytology is effective in the diagnosis of well-differentiated neoplasms.

Aged↗
PubMed1990

Mucoepidermoid carcinoma of the larynx.

Two cases of mucoepidermoid carcinoma (MEC) of the larynx are reported. The peculiarities of both cases are emphasized, in particular the site of involvement and the young age of the former and the histological subtype ("clear cell" variant) of the latter. The microscopic differential diagnosis of MEC and its biological behavior according to the grade of differentiation is discussed. The available literature is reviewed.

Adult↗
PubMed1990

Variant surface glycoprotein of Trypanosoma brucei brucei AnTat 1.1: influence of the isolation conditions upon the disulfide linked dimer/monomer ratio.

1. Using the variant surface glycoprotein (VSG) isolation procedure described by Baltz et al. ([1976] Ann. Immunol. (Inst. Pasteur) 127 C, 761-774) which involves suspension of the trypanosomes in a pH 5.5 buffer, the Antwerpen trypanozoon antigenic type (AnTat) 1.1 VSG is mainly obtained as a disulfide linked dimeric form with a trace amount of a monomeric form. 2. The use of a parasite suspension buffer at pH 7.0 results in a slight decrease of the VSG dimer/monomer ratio. 3. pH 5.5 and 7.0 supernatants of centrifuged parasite suspensions were submitted to kinetic incubations at different temperatures and pH, and we found conditions involving transformation of the AnTat 1.1 VSG dimer into the AnTat 1.1 VSG monomer (shifting the pH 5.5 supernatant to pH 7.0 and incubation at room temperature). 4. This transformation of the AnTat 1.1 VSG dimer into the AnTat 1.1 VSG monomer is activated by the addition of 1 mM reduced glutathione, and is inhibited by the addition of 1 mM oxidized glutathione or 0.1 mM N-ethylmaleimide or cadmium acetate.

Animals↗
PubMed1990

[Diagnosis of silent ischemia in patients with previous myocardial infarct, under 45 years of age].

STUDY OBJECTIVE: Diagnostic methods validation and incidence estimation of silent myocardial ischemia in patients with previous myocardial infarction under 45 years. DESIGN: Prospective in comparison with a healthy group. SETTING: Cardiac outpatients follow-up at Faro's District Hospital. PATIENTS AND PARTICIPANTS: A random group of 23 outpatients (GI) under 45 years, with previous myocardial infarction. A second group of healthy volunteers (GII) similar in age and sex. INTERVENTIONS: After discontinuing therapy, a maximal treadmill exercise test (E.T.) was performed in both groups, using the Bruce protocol. A ST segment depression greater than or equal to 1 mm, measured 80 ms after J point was the positive criteria. Simultaneously a 24 h Holter recording was obtained using a two channel real time recorder. ST segment depression greater than or equal to 1 mm, measured 80 ms after J point and lasting over 60 s., was the positive criteria. Patients with left bundle branch block or left ventricular hypertrophy criteria were excluded. Concerning ventricular arrhythmias only repetitive forms were considered. MEASUREMENTS AND RESULTS: Ten E.T. (43.5%) resulted positive in GI. Simultaneous Holter recording was positive in nine patients (one false negative). From the 13 patients with negative E.T., 12 had negative Holter recordings (one false positive). Every E.T. and simultaneous Holter resulted negative in GII. Silent ischemia was detected in eight GI patients (34.8%) all of them belonging to the subgroup with positive E.T. In four patients the silent ischemia was detected by asymptomatic E.T., and simultaneous Holter. The remaining four patients had silent ischemia diagnosed on the subsequent Holter. Silent ischemia episodes were not detected in the subgroup of 13 patients with negative E.T. Between those two subgroups it is highly significant (p less than 0.001) the difference in the incidence of silent ischemia. The patients with silent ischemia recorded an average of 6.5 episodes/patient/day mainly in day time (p less than 0.001). Episodes of silent ischemia were more frequent in the subgroup of patients with asymptomatic positive E.T. than in the subgroup of positive E.T. with pain (p less than 0.004). It was not confirmed any significant difference in the incidence of ventricular arrhythmias among patients with or without silent ischemia. CONCLUSIONS: We have verified an high incidence of silent ischemia in a group of patients with previous myocardial infarction. Holter's electrocardiographic monitoring has a high concordance with E.T. results, when performed simultaneously. In fact, it does not provide any significant additional information since every patient with silent ischemia had positive E.T., but can be complementary in the evaluation of the total ischemic burden. It has been checked that episodes of silent ischemia have a major incidence at day time, appearing more often in patients with asymptomatic positive E.T.

Adult↗
PubMed1988

Trypanosoma brucei brucei: variability in the association of some variant surface glycoproteins.

In our isolation procedure, the surface antigens of the variants AnTat 1.1 and 1.10 (Trypanosoma brucei brucei) are essentially obtained as a disulfide-linked dimer while the AnTat 1.8 surface antigen is found as a mixture of monomer and disulfide-linked dimer. This observation may be related to the localization of the cysteine residues in the protein sequences. In the purification procedure using concanavalin-A Sepharose chromatography, besides the VSG elution by methyl-alpha-D-mannopyranoside, a quantitative elution of still bound VSG may be obtained by the addition of beta-mercaptoethanol to methyl-alpha-D-mannopyrannoside in the elution buffer. The surface antigen of the variant AnTat 1.1 was examined for molecular form at several different times during the release procedure. The disulfide-linked dimer could be observed within 30 min of the surface coat release, indicating its presence within the parasite.

Animals↗
PubMed1988

Molecular heterogeneity of the isolated surface glycoprotein from variant AnTat 1.1 of Trypanosoma brucei brucei.

Variant surface glycoprotein (VSG) of Trypanosoma brucei brucei AnTat 1.1 was released by means of the procedure described by Baltz et al. ([1976], Ann. Immunol. [Inst. Pasteur] 127C, 761-774). The concanavalin-A chromatography yielded 3 VSG fractions according to the addition, in the elution buffer, of alpha-methyl-D-mannopyranoside, beta-mercaptoethanol, and sodium dodecyl sulfate. These VSG fractions showed heterogeneous behaviour on reverse-phase high performance liquid chromatography. The 3 VSG fractions as well as the myristylated VSG of AnTat 1.1 essentially consist of dimer VSG forms linked through a disulfide bridge, as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis, under reducing and nonreducing conditions.

Animals↗
PubMed1988

Aplastic anemia and neonatal giant-cell hepatitis.

The authors report the case of a female infant with bone marrow aplasia associated with neonatal giant-cell hepatitis. In addition to noting the exceptionality of this case, the possible interdependence of the two processes is discussed, and it is proposed that bone marrow aplasia, as in the adult, may represent a complication of viral disease (hepatitis).

Anemia, Aplastic↗
PubMed1987

Heterogeneity in high performance liquid chromatography of a variant surface glycoprotein of Trypanosoma brucei.

High performance liquid chromatography (HPLC) procedures have been used to analyze a preparation of the variant surface glycoprotein AnTat 1.1A of Trypanosoma brucei. The native preparation gives several peaks with a high reproducibility both by reverse-phase (RP-) and gel permeation (GP-) HPLC. Under RP-HPLC conditions, nine fractions are fully resolved. The RP-HPLC fractions migrate with the same molecular weight VSG band on polyacrylamide slab gel electrophoresis and no significant differences are observed in amino acid composition among these fractions. The RP-HPLC resolution is found to be related to the ability of the VSG to polymerize as shown using GP-HPLC. These results suggest the existence of a microheterogeneity of the AnTat 1.1A VSG preparation in relation to post-translational modification of the VSG molecule.

Animals↗
PubMed1986

Physical and immunological analysis of the two domains isolated from a variant surface glycoprotein of Trypanosoma brucei.

A specific surface glycoprotein of a variant of Trypanosoma brucei was cleaved with trypsin and the two major domains of the molecule have been purified. We have studied the chemical composition of each domain and compared the data to published results of the specific cDNA sequence. Circular dichroism measurements show that the amino-terminal domain includes preferentially alpha-helical or beta-sheet structure. The physicochemical analyses are supplemented by a prediction of secondary structure and a statistical pattern of hydrophilicity-hydrophobicity. The results are discussed in light of the internal limits that were described in the process of partial gene conversion occurring between the variant gene sequence and related members of the same gene family. Immunoblots with homologous antiserum indicate that the amino-terminal domain is implicated in antigenicity. In addition, immunoblotting with heterologous antiserum on native antigen, tryptic hydrolysates, or purified domains suggests a site of interaction supported by the two domains.

Animals↗
PubMedDate not supplied

[Unusual endocrine behavior in adrenal carcinoma. A case study].

The Authors report a case of left adrenal mass incidentally discovered by upper abdominal echogram in a 40 year old man. Physical examination showed no signs of hypercortisolism and plasma cortisol and ACTH levels were in the normal range as well as urinary free cortisol. After adrenalectomy, 4 and 8 month follow-up was performed, without clinical, hormonal and TC evolution. Thirteen months later the patient was referred to our department for widespread oedema, hypertension, hypokalemia and alkalosis. These symptoms were associated with dramatically elevated concentrations of plasmatic and free urinary cortisol. TC showed a large mass in the same adrenal region and diffuse hepatic metastases. In spite of mitotane and ketoconazole therapy the patient died few weeks later.

Adrenal Cortex Neoplasms↗