Search PubMed⌕ Search

Biomedical subjects

J Pinto

Publications and source records attributed to J Pinto.

At least 55 records · Page 3Linked to original sources
PubMed1997

Transmission of mixed malaria species and strains by mosquitoes, as detected by PCR, in a study area in Guinea-Bissau.

Parasites present in blood samples of asymptomatic carriers and in the midgut of mosquitoes collected within a few days from the same households, have been analysed by PCR. A high prevalence (32%) of infected mosquitoes was observed and, in half of these, two parasite species were found simultaneously. The distribution of parasite species in the mosquito correlated with that found in the infected persons. Genotype patterns of Plasmodium falciparum populations were however found to be different in the two sets of samples. These results and the potential of PCR are discussed with reference to investigations of the dynamics of malaria transmission.

Animals↗
PubMed1995

Transient outward currents in subendocardial Purkinje myocytes surviving in the infarcted heart.

BACKGROUND: Altered electrical activity of subendocardial Purkinje fibers contributes to arrhythmias in the 48-hour infarcted canine heart. Changes in the transmembrane action potentials of these fibers include marked action potential prolongation. The ionic basis for these changes is unknown. METHODS AND RESULTS: We used whole-cell voltage-clamp techniques to study 4-aminopyridine (4-AP)-sensitive voltage-dependent transient outward currents (Ito1) in Purkinje myocytes isolated from LV subendocardial (n = 14) and free-running (n = 15) bundles of the normal canine heart. Ito1 in these two groups of control cells (normal-zone Purkinje cells [NZPCS]) did not differ. NZPCS Ito1 was then compared with Ito1 of Purkinje myocytes dispersed from subendocardium of infarcted hearts 48 hours after total coronary artery occlusion (IZPC48, n = 14). Ito1 amplitude and current density were significantly reduced (P < .01) in IZPC48s (1650 +/- 389 pA, 9 +/- 2 pA/pF) compared with NZPCS (2917 +/- 267 pA, 20.2 +/- 2 pA/pF) at Vt = +55 mV, Vh = -60 mV, where Vt is test potential and Vh is holding potential. Decay of Ito1 was biexponential in all NZPCS but monoexponential in 71% of IZPC48s. Both NZPCS and IZPC48s have a sustained 4-AP-sensitive component (at 250 ms, Vt = +55 mV: 4 +/- 1 pA/pF, 3 +/- 1 pA/pF, respectively). Ito1 voltage dependence of inactivation did not differ between groups. In IZPC48s, recovery of Ito1 from inactivation was slowed significantly. Furthermore, significantly more Ito1 was seen with rapid pacing in NZPCS (cycle length [CL] 5000 ms = 100%, CL 1300 ms = 73%, CL 330 ms = 46%) than in IZPC48s (CL 5000 ms = 100%, CL 1300 ms = 58%, CL 330 ms = 31%). In three IZPC48s, no Ito1 was seen at CL 330 ms. CONCLUSIONS: Ito1 plays a major role in normal Purkinje myocyte electrophysiology, contributing both a large transient and a sustained component that are 4-AP-sensitive. In subendocardial Purkinje myocytes that survive in the 48-hour infarcted heart, density of Ito1 is markedly reduced and the remaining Ito1 showed specific changes in kinetics. The alterations observed in both Ito1 density and function could contribute to abnormally long transmembrane action potentials of these arrhythmogenic Purkinje myocytes of the infarcted heart.

Animals↗
PubMed1995

p53 expression in normal, dysplastic, and neoplastic laryngeal epithelium. Absence of a correlation with prognostic factors.

p53 expression has been examined in 89 squamous cell carcinomas of the larynx (34 glottic, 28 supraglottic, 18 transglottic, 8 pyriform sinus, and 1 subglottic) obtained from 88 patients surgically treated in our centre. In addition, 59 laryngeal samples including normal respiratory epithelium and non-invasive squamous cell lesions were also tested. Frozen sections were immunostained with PAb 1801 and the results were correlated with pathological features, DNA ploidy and S-phase of the tumours, disease-free interval, and survival of the patients. p53 immunoreactivity was observed in 57 (64 per cent) carcinomas. None of the eight samples of normal respiratory epithelium was positive. p53-positive cells were seen in 8 of 23 (35 per cent) squamous cell metaplasias, 6 of 19 (32 per cent) low-grade dysplasias and 5 of 10 (50 per cent) high-grade dysplasias. No correlation was found between p53 expression in carcinomas and their clinical and pathological characteristics, DNA ploidy, or proliferative activity. Neither disease-free nor overall survival showed differences between p53-positive and p53-negative cases. These findings indicate that p53 may play a role in an early stage of malignant transformation of a subset of squamous cell carcinomas of the larynx, but seems not to be associated with further progression of the tumours.

Adult↗
PubMed1995

Altered glutathione metabolism in the tumor-bearing state.

BACKGROUND: Because glutathione (GSH) appears to be important for tumor growth and many tumors contain the capacity (gamma-glutamyltranspeptidase) to transport GSH, we examined GSH metabolism in MCA sarcoma-bearing rats (TB). METHODS: Tumor, liver skeletal muscle, kidney, and serum were collected from 47 MCA sarcoma (TB) rats and 26 normal (CTL) rats. Amino acids, GSH, gamma-glutamylcysteine synthetase (GCS), and gamma-glutamyl transpeptidase (GGTP) were determined. RESULTS: Significant activity of GGTP (117.8 +/- 16.0 mU/min/mg protein) was present in tumors. Liver GCS activity (nanomolar per hour per milligram protein) in TB rats (106.6 +/- 37.7) was increased (p < 0.01) compared with CTL rats (57.5 +/- 12.3) and correlated positively with tumor burden (R = 0.77). Muscle GGTP was decreased (p = 0.001) in TB rats (1.7 +/- 1.1) compared with controls (6.8 +/- 1.1). Serum GSH concentrations (microM) were lower (p < 0.05) in TB rats (14.97 +/- 1.72) versus control rats (16.82 +/- 1.54) and correlated negatively with tumor burden (R = -0.83). CONCLUSIONS: In this tumor-bearing model, tumor has significant capacity (GGTP) for the uptake of GSH. Serum GSH is depleted in TB rats and correlates negatively with tumor burden. Liver GCS is increased in TB rats and skeletal muscle GGTP is decreased, which may preferentially benefit the tumor by increasing the bioavailability of glutathione for its own use.

Amino Acids↗
PubMed1995

Sinonasal teratocarcinosarcoma: an unusual neoplasm.

Sinonasal teratocarcinosarcoma (SNTCS) is a very unusual and aggressive neoplasm characterized by the combination of malignant teratoma and carcinosarcoma features, of which less than forty cases have been reported in the literature. We report on a 75-year-old man with SNTCS that involved the left ethmoid, maxillary and sphenoidal sinuses. The tumor showed a complex histological pattern with mature and immature glands, benign squamous and malignant poorly differentiated epithelia, as well as neuroblastoma-like tissue and sarcoma component with rhabdomyoblastic differentiation. This peculiar blend of tissue types makes the diagnosis of this entity a difficult challenge, especially in small biopsies or in tumors only partially removed. This tumor must be differentiated from several types of carcinomas, esthesioneuroblastoma, craniopharyngioma, malignant mixed tumor of salivary gland type and germ cell tumors. The present case represents, to our knowledge, the third SNTCS described in the european literature.

Aged↗
PubMed1995

[Prognostic factors of hepatocellular carcinoma: a multivariate analysis in 113 patients].

UNLABELLED: The aim of this study was to identify clinical, biological or morphological prognostic factors in 113 patients with HCC in terms of survival. All patients (100 men, aged 65 [28-85], 95% cirrhosis) were diagnosed between 1982-1990. Mean survival time was 21 +/- 3 weeks. Eleven (over 25) variables were isolated by univariate analysis. A multivariate survival analysis (Cox regression model) disclosed that serum creatinine (p = 0.0002), alkaline phosphatase (p = 0.02) and Okuda's stage (p = 0.025) were independent predictors of survival. Comparison of survival curves for different values of these prognostic variables allows division of patients in three groups of prognostic significance in terms of survival (p < 0.05). CONCLUSION: these results facilitate stratification of patients with HCC to design and evaluate future controlled trials.

Aged↗
PubMed1994

Effect of epidermal growth factor on the growth and radiation sensitivity of human breast cancer cells in vitro.

PURPOSE: To study the effect of epidermal growth factor (EGF) on the radiation sensitivity of MCF-7 breast cancer cells. METHODS AND MATERIALS: Radiation dose survival curves were generated for MCF-7 cells under conditions of hormonal deprivation. Epidermal growth factor and/or a monoclonal antibody to its receptor (mAb-225) were added prior to irradiation. Cell cycle distribution was determined by flow cytometry and cellular glutathione (GSH) levels were measured by a glutathione reductase assay. RESULTS: Under hormonal deprivation (control), more than 90% of the MCF-7 cells were arrested in G0/G1 phase and the D(o) of their survival curve was 0.66 +/- .01 Gy. The addition of EGF resulted in (a) growth stimulation; (b) increased percentage of cells in the S-phase of the cell cycle; (c) increased radioresistance (D(o) = 0.81 +/- .04 Gy; p < .05, compared with controls); (d) increased cellular GSH level. The EGF effect on radiation response was observed in a time- and dose-dependent manner. The addition of mAb-225 blocked the ability of EGF to enhance growth and radioresistance (D(o) = 0.68 +/- .03 Gy). CONCLUSION: Epidermal growth factor stimulates the growth and when administered prior to irradiation increases the radioresistance of hormone-deprived MCF-7 cells. These effects are inhibited by a specific antibody to the EGF receptor. Epidermal growth factor concomitantly increased the fraction of S-phase cells and intracellular GSH levels. This system of growth factor-altered radiosensitivity in human breast cancer cells provides a useful model for the study of the radiation response mechanisms in human malignancy.

Antibodies, Monoclonal↗
PubMed1994

Tissue autofluorescence as an intermediate endpoint in NMBA-induced esophageal carcinogenesis.

The capacity to identify subclinical neoplastic disease of the upper aerodigestive tract (UADT) using tissue auto-fluorescent spectroscopy would significantly contribute to cancer screening. Rats received N-nitrosomethyl benzylamine (NMBA), a carcinogen shown to cause esophageal malignancies. Following sacrifice at early weekly intervals, gross assessment of esophageal mucosa of NMBA-exposed rats was indistinguishable from saline-treated controls. Histopathologic evaluation, however, revealed NMBA-induced preneoplastic changes in the epithelium. Concurrent with these changes, the NMBA-exposed rats demonstrated specific alterations in autofluorescence. These results demonstrate that NMBA-induced esophageal premalignancy can be distinguished by autofluorescent properties. The capacity to detect alterations in autofluorescence may allow more sensitive screening of UADT mucosa at risk for cancer development.

Animals↗
PubMed1994

Immunostimulatory effect of thalidomide in normal C57BL/6 mice is compatible with stimulation of a highly connected central immune system.

Although thalidomide has been used with success in the treatment of increasing numbers of autoimmune diseases, the therapeutic effects have not been satisfactorily explained so far. We describe here some findings that may contribute to a better understanding of the immunomodulatory effects of this drug. Several immunological changes were observed after treating C57BL/6 mice with 3 mg of thalidomide. The numbers of natural IgM PFC against sheep red blood cells were increased in the spleen, and occasionally a dramatic oscillatory increase in the numbers of non-specific splenic IgM and IgG PFC was observed in these mice. However, these oscillatory increases were progressively lower, after two and three treatments with thalidomide at 20-day intervals. Furthermore, the absolute numbers of splenic CD5+ B and CD5- B lymphocytes were increased whereas depletion of CD4+ CD8+ cells in the thymus and of lymphoid cells in the bone marrow was seen after a single treatment with 3 mg of thalidomide. Taken together, these results suggest that thalidomide stimulates both peripheral and central immune systems and consequently enhances the connectivity of the central immune system.

Animals↗
PubMed1994

[Mushroom poisoning in the IX region. Role of Amanita gemmata].

We report four episodes of mushroom poisoning that occurred between 1986 and 1990 in the province of Malleco. Twenty five of 36 individuals who ingested the mushroom became ill; they had an acute gastroenteritis that was followed in 7 by an acute hepatitis and in one by a massive upper gastrointestinal bleeding. Three subjects with fulminant hepatic failure and the subject with the massive bleeding died. Amanita gemmate (strain described as toxic in Chile since 1967) was found in two episodes and Amanita sp in one. The clinical picture is similar to that described for Amanita phaloides. The treatment is symptomatic but penicillin and silymarin may have an antitoxic action. The importance of warning the population about the existence of toxic mushrooms in Chile is emphasized.

Adult↗
PubMed1993

Affinity purification and subcellular localization of kinesin in human neutrophils.

Studies of granule-microtubule interactions in human neutrophils have suggested that mechanochemical ATPases such as kinesin or dynein may play a role in granule mobilization during neutrophil activation by inflammatory signals. In this study we show that proteins extracted from the surface of neutrophil granules, found previously to contain microtubule-dependent ATPase activity, caused microtubules polymerized from phosphocellulose-purified rat brain tubulin to move across glass slides. Antibodies were generated against peptides based on two regions of the amino acid sequence of Drosophila kinesin: the ATPase active site (amino acids 86-99) in the head of the kinesin heavy chain and the tail of the heavy chain (residues 913-933). These antibodies were found to recognize kinesin in rat brain extracts as well as kinesin-like polypeptides in extracts of human neutrophils. Furthermore, when used in immunoaffinity chromatography, these antibodies permitted the isolation of a protein from neutrophil granule extracts that was recognized by Drosophila kinesin antibodies. Subcellular localization by immunofluorescence microscopy showed this protein to be associated principally with the cytoplasmic granules of neutrophils.

Animals↗
PubMed1992

Protein intake and blood glucose as modulators of GFR in hyperfiltering diabetic patients.

Glomerular hyperfiltration has been claimed to be a risk factor for the development of diabetic nephropathy. Protein intake and hyperglycemia can both increase GFR in diabetic and normal subjects. Our study was designed to explore the relative importance of short-term changes in protein intake and glycemia on the modulation of renal hemodynamics in insulin-dependent diabetic (IDDM) patients with and without glomerular hyperfiltration. The renal hemodynamic response to a protein challenge was studied in eight hyperfiltering (HF) and eight normofiltering (NF) patients after a three week period of low or normal protein diet (LPD, NPD), each study being conducted twice, in random order, under conditions of prevailing hyperglycemia (H) and euglycemia (E). In HF patients GFR failed to increase significantly in response to protein challenge during NPD under conditions of either H or E (Baseline vs. 2 hr H: 151 +/- 4 vs. 155 +/- 6, NS; E 147 +/- 4 vs. 157 +/- 7 ml/min/1.73 m2, NS). A more normal response was restored following LPD with GFR increasing in all but one patient after challenge during H and in all patients during E (Baseline vs. 2 hr H: 130 +/- 7 vs. 145 +/- 8, P less than 0.07; E: 127 +/- 7 vs. 143 +/- 7 ml/min/1.73 m2, P less than 0.01). Changes in RPF paralleled the changes in GFR and filtration fraction remained stable under all study conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Control of ventricular fibrillation after coronary artery occlusion via intracerebroventricular injections.

The central nervous system (CNS) may play a larger role than previously thought in the development of ventricular fibrillation after coronary artery occlusion. The probability of ventricular fibrillation after complete, permanent occlusion of the left anterior descending coronary artery was 52% in conscious control pigs. After the administration into the lateral cerebral ventricle of tyrosine, the amino acid precursor of the catecholamine neurotransmitters, 100% of the animals developed ventricular fibrillation. After tyrosine plus propranolol, a beta-adrenoceptor antagonist, only 9% of pigs developed ventricular fibrillation. Treatment with propranolol alone did not affect the outcome. Catecholamine synthesis in the CNS may be associated with the development of ventricular fibrillation after coronary artery occlusion.

Animals↗