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R Segura

Publications and source records attributed to R Segura.

80 records · Page 5Linked to original sources
PubMedDate not supplied

Influence of prolonged exercise on myocardial distribution of 123I-MIBG in long-distance runners.

BACKGROUND: A study was conducted to determine if prolonged exercise could provoke sympathetic neuronal alteration in an athlete's heart through assessment of myocardial distribution of 123I-metaiodobenzylguanidine (MIBG) in nine ultramarathon runners at baseline and after a 4-hour race. METHODS AND RESULTS: After injection of 370 MBq of 123I-MIBG, the athletes ran for 4 hours, covering 45 +/- 8 km. Planar and single-photon emission computed tomography (SPECT) images of the thorax were acquired at the end of the race. Two weeks later, studies at baseline were performed. A heart:mediastinum ratio (HMR) was calculated to quantify MIBG uptake. Basal MIBG studies showed normal myocardial tracer uptake, on both planar and SPECT images, and the HMR was 1.84 +/- 0.16. After the 4-hour race, MIBG studies showed decreased myocardial uptake in all athletes, and the HMR was 1.70 +/- 0.18 (p < 0.005). A positive correlation between the percentage of decrease of HMR after the race and the distance covered was observed (r = .910, p < 0.001). CONCLUSIONS: Myocardial MIBG activity is decreased by prolonged exercise in long-distance runners. The degree of reduction of myocardial MIBG activity is related to the distance covered. Prolonged exercise, as sustained sympathetic stimulus, may alter myocardial distribution of MIBG.

3-Iodobenzylguanidine↗
PubMedDate not supplied

Experimental diets for the study of lipid influence on the induced mammary carcinoma in rats: I--Diet definition.

There is a considerable variation in the diets used in studies on the influence of dietary fat on rat mammary cancer. In view of the fact that diet is the most remarkable factor in these studies, the aim of this work was to define two experimental diets, one of them normal (N3) and another hyperlipidic (HL20), both allowing the normal growth of the rat and neither of them containing factors that could unspecifically affect mammary carcinogenesis. Semisynthetic diets were selected instead of natural ones. A normal diet (3% corn oil, 18% casein, 67.9% dextrose) and a hyperlipidic diet (20% corn oil, 23% casein, 45.9% dextrose) were defined for the rat. Both diets also contain 5% cellulose, 5.9% salt mix and 0.24% vitamin mix. In order to avoid the influence of the above mentioned unspecific factors, the control of specificity and quality of nutrients is proposed as an essential measure. Moreover, it is also necessary to adopt measures to avoid the presence of fatty acid metabolites, including the calculation of the necessary vitamin E, selenium and sulfur amino acid and the determination of factors potentially able to stimulate or inhibit carcinogenesis such as phenolic antioxidants, retinoids or the trans isomer of fatty acids. On the other had, casein, dextrose, choline and folic acid contents were modified in order to equilibrate the lipid increase experimentally introduced in the HL20 diet or to ensure the normal maintenance of the animals' metabolism. The method used is based on the concept of quality assurance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMedDate not supplied

Experimental diets for the study of lipid influence on the induced mammary carcinoma in rats: II--Suitability of the diets.

We have previously reported one method for obtention of experimental diets for the study of the effects of dietary lipids on the rat breast carcinoma. The purpose of this second part of the study was to develop a quality control system for demonstrating the suitability of these diets. This system is essentially based on the animals' growth control, their period clinical examination as well as the anatomopathological postmortem study of the animals submitted to such diets. Two groups of weaning rats, control (C) and hyperlipidic (HL), were submitted to a low-fat diet (N3) or a high-fat polyunsaturated--corn oil--diet (HL20) respectively. At 53 days of age all animals were induced with 5mg of dimethylbenz (a) anthracene. Experiments were ended when animals reached a mean age of 214 days. The results show: 1) a normal ponderal evolution of the animals in the two experimental groups with respect to two series of the same strain fed with a standard diet, and 2) the homogeneity of growth determined by the coefficient of variance study. On the other hand, neither the weekly clinical examination nor the anatomopathological post-mortem studies revealed any pathology that could be specifically attributed to nutritional imbalance. These results confirm the suitability of both diets for rat growth. Their use in the study of the effects of dietary lipids on the mammary carcinoma would satisfy the initial aim of guaranteeing the specificity of the results.

Animal Feed↗
PubMedDate not supplied

[Utilization of veno-venous bypass in orthotopic liver transplantation].

BACKGROUND AIMS: The aim of the present study was to evaluate the hemodynamic effects of venovenous bypass (VVB) and its possible protective action during the clamping of the hepatic vessels carried out in the anhepatic phase of the orthotopic liver transplantation. PATIENTS AND METHODS: Forty-one liver transplant patients, 15 of whom were operated with VVB, were studied. VVB consisted of a bridge from the primitive iliac veins and the portal vein to the left axillary vein. The hemodynamic, metabolic and biologic variables as well as the components of reposition and the drugs administered were measured. The results obtained in both groups were statistically compared and analyzed. RESULTS: During the anhepatic phase the values of cardiac output did not modify in the patients operated with VVB, while these values significantly decreased in other patients. Peripheral resistances increased less in the VVB group. During the reperfusion phase there were no significant differences between the hemodynamic parameters of either group. The decrease in temperature during the anhepatic phase was significantly greater in the VVB group. CONCLUSIONS: Venovenous bypass offers greater hemodynamic stability during the anhepatic phase of orthotopic liver transplantation.

Adult↗