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Biomedical subjects

L Gil

Publications and source records attributed to L Gil.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effects of muscle electrical stimulation on peak VO2 in cardiac transplant patients.

Peak oxygen consumption (peak VO2) has become a critical component in the evaluation of heart transplant recipients (HTR). In these patients, peak VO2 remains low after cardiac transplantation mainly because of persisting peripheral limitations in the working muscles. Muscular electrical stimulation, on the other hand, has been shown to enhance the oxidative capacity of healthy muscle. It was the purpose of our investigation to study the effects of ES on the peak VO2 of HTR. Fourteen (11 males and 3 females) HTR (age: 57+/-7yr, mean +/- SD; height: 163+/-7 cm, weight: 70.5+/-8.6 kg) were selected as subjects and each of them was randomly assigned to one of two groups: (a) group EXP (n = 7), receiving electrical stimulation on both quadriceps muscles during a period of 8 weeks, and (b) group CONT (n = 7), not receiving electrical stimulation. Before (PRE) and after (POST) the aforementioned 8-week period, respectively, all the subjects performed a cardiopulmonary exercise test (ramp protocol) on a cycle ergometer for peak VO2 determination. PRE values of peak VO2 were similar in both groups (17.1+/-2.0 vs 16.9+/-3.8ml x kg(-1) x min(-1) in EXP and CONT, respectively). However, peak values of VO2 significantly increased in EXP (p < 0.05) after the period of electrical stimulation (POST peak VO2: 18.7+/-2.0ml x kg(-1)), whereas no change was observed in CONT (POST peak VO2: 16.2+/-3.2 ml x kg(-1) x min(-1)). In conclusion, electrical stimulation could therefore be used to improve the functional capacity of HTR, and might be included in the rehabilitation programs of this population group.

Electric Stimulation↗
PubMed1998

Continuous intravenous intradialysis versus intravenous postdialysis erythropoietin therapy in chronic haemodialysis patients: a randomized, controlled, crossover study.

BACKGROUND: Subcutaneous recombinant human erythropoietin seems to be more effective than intravenous administration. Local pain, however, may diminish patient compliance with the subcutaneous route. Recently continuous intravenous intradialysis administration of rHuEpo has been reported to be more efficacious in stimulating erythropoiesis than the usual postdialysis intravenous bolus. METHODS: We conducted a randomized, controlled, crossover study on stable chronic haemodialysis patients to compare the efficacy of continuous intradialysis rHuEpo therapy with intravenous postdialysis administration. Twenty patients were selected and randomly assigned to receive rHuEpo either postdialysis (control phase) or by continuous intradialysis perfusion (slow Epo phase) for 12 weeks. After this period, patients were switched to the alternative method for 12 additional weeks. The erythropoietin dose remained unchanged during the study. Haematocrit was monitored weekly and iron metabolism, serum Epo, and vitamins were measured monthly. Urea kinetics and iPTH measurements were performed every 3 months. RESULTS: Three patients were excluded because of unrelated problems. The final mean haematocrit was unchanged from previous basal values in both phases and no statistical differences were found for any parameter between the groups. No differences were found in iron metabolism nor in urea kinetic parameters. CONCLUSIONS: Continuous intravenous intradialysis administration of rHuEpo is not more effective than an intravenous postdialysis bolus as rHuEpo maintenance therapy in stable chronic haemodialysis patients.

Adolescent↗
PubMed1998

The cholesterol/phospholipid ratio of the erythrocyte membrane in children with familial hypercholesterolemia. Its relationship with plasma lipids and red blood cell aggregability.

The cholesterol/phospholipid ratio (C/PL) of the red blood cell membrane, plasma lipids and erythrocyte aggregability were evaluated in 20 children with familial hypercholesterolemia (age: 10.4+/-4.6 years) but without detectable vascular injury. The results indicate that hypercholesterolemic children have a higher erythrocyte membrane C/PL ratio than the control group (0.81+/-0.23 vs. 0.65+/-0.08, p < 0.01). This membrane lipid alteration correlates inversely with the plasma concentration of HDL-cholesterol (r = -0.558, p < 0.010). The patients also showed greater erythrocyte aggregability than the control group (8.21+/-1.11 vs. 6.25+/-1.24, p < 0.001), but this does not seem to correlate with the changes observed in the lipid composition of the cell membrane. These results suggest that from childhood, people with familial hyper-cholesterolemia show alterations in the lipid composition of the red blood cell membrane that are related to the changes observed in plasma lipids and appear prior to atherosclerotic vascular symptoms.

Child↗
PubMed1997

Hepatic enzyme induction and mutagenicity of airborne particulate matter from Santiago, Chile in the nourished and malnourished rat.

1. Respirable, airborne particles in the ambient air in downtown Santiago, Chile, have been characterized for the seasonal variation in total polycyclic aromatic hydrocarbon content, 13 of which have been identified including the mutagens (benzo(a)pyrene, dibenzo(a,h)anthracene, benzo(a)anthracene, benzo(b)fluoranthene and indeno(1,2,3, c,d)pyrene amongst others. 2. Organic extracts derived from these particles were administered to both the nourished and malnourished rat and resulted in modulation of the hepatic mixed function oxidase system including induction of NADPH-cytochrome P450 reductase, cytochrome P4501A as determined by Western blot analysis and the associated ethoxyresorufin O-deethylase and aryl hydrocarbon hydroxylase activities. 3. The cytochrome P4504A1-dependent 12-hydroxylation of lauric acid was induced in the malnourished state, but this activity was significantly inhibited by treatment of the animals with particle extracts in both nutritional states. 4. The particle extracts contained both direct and indirect-acting mutagens in the Ames test, and depending on the relative complement of both, resulted in either increased or decreased mutagenicity in the presence of S9 activation systems derived from both nourished and malnourished animals. 5. These results are discussed in the context of the interindividual risk assessment of airborne, particulate matter to man.

Air Pollutants↗
PubMed1996

Erythrocyte membrane cholesterol/phospholipid changes and hemorheological modifications in familial hypercholesterolemia treated with lovastatin.

Fourteen patients with familial hypercholesterolemia treated with lovastatin (40 mg/day) for three months were studied to find out whether the expected changes in plasma lipids are accompanied by modifications in the lipid composition of the erythrocyte membrane and whether these in turn induce changes in the rheological behavior of the red blood cell. Our results demonstrate the efficacy of lovastatin in reducing the plasma concentration of cholesterol and LDL cholesterol. The changes observed in the plasma lipids correlate with a significant decrease in the cholesterol/phospholipid ratio of the red blood cell membrane, from 1.19 +/- 0.19 in a basal situation to 0.92 +/- 0.23 (p < 0.01) at the end of treatment. These changes in the lipid composition of the cell are statistically related to a decrease in erythrocyte aggregability and an improvement in blood filterability, which means beneficial change in the patients' hemorheological situation.

Adult↗
PubMed1996

Effect of HMG-CoA reductase inhibitors on red blood cell membrane lipids and haemorheological parameters, in patients affected by familial hypercholesterolemia.

Eighteen patients with familial hypercholesterolemia treated with lovastatin (40 mg/day) for three months were studied to find out whether the drug induces modifications in the lipid composition of the erythrocyte membrane and whether these induce changes in the rheological behaviour of the red blood cell. Our results show that the changes observed in plasma lipids correlate with a significant decrease in the cholesterol/phospholipid ratio of the red blood cell membrane. These changes in the lipid composition of the cell are statistically related to a decrease in the erythrocyte aggregability and an improvement in blood filterability probably due to an increase in the red blood cell deformability.

Adult↗
PubMed1995

Induction of rat hepatic P4501A1 by organic extracts from airborne particulate matter in Santiago, Chile.

1. Organic extracts from particulate matter collected in downtown Santiago, Chile, in 1990 were administered to female Wistar rats. 2. Extracts shifted the maximal absorption wavelength P450 spectra of the reduced-CO complex of hepatic microsomal P450 from 450 to 448 nm, and enhanced the total content of P450. In addition, substantial increases in aryl hydrocarbon hydroxylase, ethoxyresorufin O-deethylase and ethoxycoumarin O-deethylase activities were observed, whereas aminopyrine N-demethylase activity was not affected by treatment. 3. Western blotting using polyclonal antibodies against P4501A isozymes showed the appearance of a distinct and intense P4501A1 band in microsomes from rat pretreated with air particle extracts, and was not observed in microsomes from control rat. On the other hand, the intensity of the P4501A2 isoenzyme was apparently not affected. 4. These findings suggest that the organic extracts from airborne particulate matter modify the composition of rat liver P450 isozymes by inducing those isoforms responsible for the activation of precarcinogenic to carcinogenic agents.

Air Pollutants↗
PubMed1995

[Impact of outdoor pollution on indoor air quality. The case of downtown Santiago (Chile)].

The influence of outdoor pollution on indoor air quality was studied in downtown Santiago(Bandera street). Carbon monoxide (CO), nicotine, particulate matter, respirable fraction (PM5) and total and carcinogenic polyaromatic hydrocarbons (PAHs) were simultaneously monitored indoors and outdoors in restaurants, offices and other places. The levels of CO changed simultaneously outdoors and indoors (r = 0.89) specially during traffic rush hours, demonstrating the importance of outdoor infiltration into the indoor air quality and masking the contribution of other CO indoor sources. The maximum CO concentrations were over 800% and over 1000% higher indoors and outdoors respectively than the 9 ppm CO National Ambient Air Quality. The PM 5 concentrations were very high and showed no significant differences (p > 0.05) from indoors to outdoors, or between indoor levels in restaurants, offices and other places. Total and carcinogenic PAHs levels were also very high outdoors and indoors, outdoor levels being generally higher than those indoors and no significant; differences (p > 0.05) were found for the indoor levels between restaurants, offices and other places. Nicotine levels showed significant differences (p < 0.05) between indoor and outdoor levels. In addition, great differences (p < 0.05) in indoor levels, were found between offices and restaurants, and offices and other places. Among indoor sources cigarette smoke seems to be a minor source since nicotine concentrations, being 2.3 times higher in restaurants and other places than in offices, do not contribute to enhance significantly PM5 and total and carcinogenic HAPs in the first ones. These results suggest that in downtown Santiago, infiltration might be the main source of indoor pollution. This is supported by two evidences: a) coronene, a tracer of vehicle emissions was found in high concentration indoors and b) in restaurants (in which PAHs emissions might be higher indoor) a correlation coefficient of 0.987 for the indoor and outdoor concentrations of carcinogenic PAHs was found. Furthermore a survey asking for different symptoms and effects probably related to air pollution was made to people working in Bandera and in a rural area located 40 Km from Santiago. The results showed that excluding smoking as a confoundend factor, people working in Bandera showed a significantly greater (p < 0.05) risk of ill effects on their health than people working in the rural area.

Air Pollutants↗
PubMed1993

Mutagenicity of organic extracts from Santiago (Chile) airborne particulate matter.

The Ames test has been used to detect the mutagenic activity of organic extracts from Santiago (Chile) airborne particles collected in 1990 and 1991 in one of the monitoring net system stations (MACAM). The samples were assayed with the strains TA98, TA98-NR, and TA98/1,8-DNP6 of Salmonella typhimurium, in the presence and in the absence of liver S9 fraction obtained from rats treated with Aroclor 1254. With the strain TA98 all the samples showed a very high mutagenic response either in the presence or in the absence of S9 fraction, suggesting that Santiago airborne particles contain both indirect-acting (polycyclic aromatic hydrocarbons) and direct-acting mutagenic agents. The mutagenicity of Santiago airborne particles was much higher than that reported in studies performed in other countries. Results obtained with the strains TA98-NR and TA98/1,8-DNP6 suggest that the extracts also contain mononitro and dinitroarenes. These nitroarenes have been described as very potent mutagenic agents, that can be generated by photochemical reactions under certain atmospheric conditions, or in the combustion of fuel, especially of diesel motors. The presence of polycyclic aromatic hydrocarbons and nitroarenes in Santiago airborne particles, as well as the high levels of mutagenicity detected, suggest that the inhabitants permanent exposure to these kinds of compounds represents a high risk for human health.

Air Pollutants↗