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Biomedical subjects

C Mota

Publications and source records attributed to C Mota.

14 recordsLinked to original sources
PubMed1999

Cholesterol may act as an antioxidant in lens membranes.

PURPOSE: Oxidative damage has been considered as a major factor involved in cataract formation. We have recently shown that cholesterol oxides accumulate in human cataractous lenses. The biological significance of accumulation of oxysterols in the lens is still poorly understood. However, it has been proposed that cholesterol may act as an antioxidant. This study was designed to establish whether cholesterol may act as an antioxidant in the lens. METHODS: Bovine lens membranes (BLM) were oxidised by incubation with an azo-compound. Lipid hydroperoxides were measured by the FOX-assay, vitamin E was determined by HPLC, cholesterol and cholesterol oxides were isolated in a C18 column and quantified by gas chromatography. Susceptibility of liposomes and BLM to oxidation was determined by the fluorescence quenching of parinaric acid. RESULTS: Oxidation of BLM results in the production of lipid hydroperoxides, consumption of endogenous vitamin E and formation of cholesterol oxides. Cholesterol presents some important characteristics generally ascribed to an antioxidant molecule: its presence in liposomes increases the vesicle resistance to oxidation and its oxidised forms are stable as they are unable to stimulate further propagation of peroxidation reactions. Moreover, the protective effect of cholesterol in liposomes is comparable to that of vitamin E, suggesting that cholesterol possibly acts by intercepting the peroxyl radicals formed during lipid peroxidation. CONCLUSIONS: Although cholesterol oxides may present a variety of noxious effects in the cells its presence in lens membrane is likely to be associated with the expression of its antioxidant effect, contributing to maintain lens transparency.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1998

Cardiac consequences of renal transplantation changes in left ventricular morphology.

OBJECTIVE: The aim of this study was to characterize changes in left ventricular morphology and function by conventional echocardiography in a pediatric population after renal transplantation (RT). MATERIAL AND METHODS: This study includes 21 children, 11 female and 10 male, aged 11.8 +/-2.6 years at the time of renal transplantation. Eleven were on regular hemodialysis treatment and two on continuous peritoneal dialysis for 31.8 +/- 31.6 months; eight were transplanted without prior dialysis. Eight children were hypertensive before RT and nine (seven de novo) after RT. The patients were analysed in a prospective follow-up study with echocardiography immediately before and 30.2 +/- 15 months after successful renal transplantation. We measured the following echocardiographic parameters: Left ventricular end diastolic (LVED) and end systolic diameter (LVES), left atrial dimension (LAD), septal thickness (IVST), posterior wall thickness (PWT), shortening fraction (SF) and left ventricular index mass (LVIM). The paired Student's test, Fisher exact test and Pearson's correlation were used for statistical analysis. We analyzed the echocardiographic changes in the total group and separately in the subgroups with and without prior hemodialysis, as well as the influence of the duration of dialysis, anemia and hypertension. RESULTS: 1. After renal transplantation we found a decrease in the LVED LVES, LAD, IVST and PWT measurements (p < 0.05). There was a negligible increase in SF. The LVIM decreased from 139 g/m2 to 104 g/m2, representing a 21% reduction of the initial value, but this reduction was not of statistically significant. 2. The findings were similar in the hemodialysis group-LVIM decreased from 167.6 g/m2 to 94.9 g/m2, representing a 35% reduction in the initial value. 3. In the non dialysis group LVED, LVES, LAD and SVT decreased and LVIM showed a minor increase. There was a negligible increase in SF. 4. We found an increased LVIM in children with prior hemodialysis before RT, especially if dialysis lasted for more than two years. 5. Amelioration of hematocrit correlated with reduction of LVIM. 6. Regression of LV hypertrophy after RT was not dependent on blood pressure levels. CONCLUSIONS: Renal transplantation resulted in a tendency towards normalization of the echocardiographic parameters analysed: Contractility, as assessed by shortening fraction, was normal in this population. Although cardiac hypertrophy and dilation is reversible after RT, it would seem that children may benefit from an earlier transplantation.

Adolescent↗
PubMed1995

Echocardiographic evaluation of partial anomalous pulmonary venous drainage.

OBJECTIVES: This study was undertaken to determine the accuracy of routine echocardiography in the detection of partial anomalous pulmonary venous drainage. BACKGROUND: Although there are occasional case reports of the echocardiographic appearance of partial anomalous pulmonary venous drainage, no large series have addressed the accuracy of this technique in a large cohort of patients. METHODS: Between January 1983 and December 1993, 50 patients with partial anomalous pulmonary venous drainage (with or without an associated atrial septal defect as the only other significant intracardiac defect) were identified from the data base at the Hospital For Sick Children, Toronto. Routine echocardiographic reports were reviewed, and the results were compared with surgical or catheterization findings. Risk factors related to diagnostic errors were sought using a Fisher exact test, chi-square analysis, t test and Kruskal-Wallis analysis of variance. RESULTS: Confirmation of the diagnosis was available in 45 patients whose data were subsequently used for risk factor analysis. The median age at echocardiography was 4.1 years (range 1 month to 18 years). Right-sided drainage was present in 43 patients (86%), with left-sided drainage in 7 (14%). Thirteen patients had an intact atrial septum, 7 a patent foramen ovale and 30 a secundum atrial septal defect. Right ventricular dilation was observed in 46 patients. Two had normal dimensions (two not assessed). The diagnosis was missed by echocardiography in 15 (33%) of the 45 patients with a confirmed diagnosis. Year of study and use of color flow mapping were the only significant variables related to detection rate (7% missed diagnosis with vs. 62% without the use of color flow, p < 0.0005). The median year of missed diagnosis was 1985 versus 1990 (p < 0.002). Transesophageal echocardiography accurately defined the site of drainage in all three patients in whom it was utilized. CONCLUSIONS: Two-dimensional echocardiography in conjunction with color flow mapping is a valuable tool for the diagnosis of partial anomalous pulmonary venous drainage.

Adolescent↗
PubMed1989

Serum aspirin-esterase activity in epileptic patients receiving treatment with phenobarbital, phenytoin, carbamazepine and valproic acid.

Serum aspirin-esterase activity was studied in a group of epileptic patients under treatment with phenobarbital, phenytoin, carbamazepine and valproic acid, and a group of healthy controls. Serum rates of hydrolytic activity as well as serum esterase activity were found to be higher in epileptics (p less than 0.001) than in controls. The findings suggest that the above-mentioned antiepileptic drugs may induce plasma esterase activity, thus leading to increases in serum hydrolytic activity in epileptic subjects. On the other hand, no sex or albumin-related differences were observed in serum aspirin-esterase activity in the groups investigated.

Adult↗
PubMed1989

Probable pseudocholinesterase induction by valproic acid, carbamazepine and phenytoin leading to increased serum aspirin-esterase activity in epileptics.

The present findings show clearly that valproic acid, carbamazepine and phenytoin are each capable of significantly raising serum aspirin-esterase activity in epileptics being treated with these drugs (between p less than 0.01 and p less than 0.05). The data suggest that these antiepileptic drugs may well act as enzymatic-inducing agents upon plasma cholinesterase (or pseudocholinesterase) in epileptic patients.

Adolescent↗
PubMedDate not supplied

[Central diabetes insipidus: a case report].

INTRODUCTION: Diabetes insipidus (DI) is a syndrome characterised by polyuria which is almost always associated with polydipsia. The most frequent cause is central DI, which is the result of an inadequate secretion of the diuretic hormone, and diagnosis involves differentiating it from other causes of polyuria and polydipsia. CASE REPORT: The authors report the clinical case of a previously healthy 4 year old girl, who, in December 1998, was found to have intense polydipsia accompanied by polyuria. Behavioural treatment was begun as an answer to what was thought to be psychogenic polydipsia, although results were unsatisfactory and the patient was brought to the Paediatric Nephrology Service at Hospital Maria Pia in June 1999. CONCLUSION: A clinical study, which included the water restriction test and concentration tests with desmopressin, enabled us to diagnose central DI. In spite of the results from a cranial NMR scan being normal, follow up time is still too short to classify the aetiology as idiopathic. The girl is asymptomatic under treatment with intranasal desmopressin. The favourable evolution in this case highlights the need to act in a thorough manner in the study of situations involving polyuria/polydipsia.

Child, Preschool↗