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Biomedical subjects

L Yañez

Publications and source records attributed to L Yañez.

7 recordsLinked to original sources
PubMed1998

[Reliability of optic density at 650 nm in determining lung maturity in children of diabetic mothers].

The Diabetes Mellitus is the pathology that frequently is associated to the pregnancy and it is responsible for perinatal mobility specially by the respiratory distress syndrome since exists delay in the conversion of myoinositol-phosphatidyl inositol-phosphatidyl glycerol. To demonstrate the reliability of the DO tho 650 nm with standard of 20 in the determination of fetal lung maturity of the infant of diabetic mother. There were included 143 patient with pregnancy > or = 37 weeks with amenorrhea reliable and gestational age confirmed by ultrasound, of those 94 corresponded to gestational Diabetes Mellitus, 49 to pregestational (46 non insulin-dependent and 3 insulin-dependent). In all of them amniotic fluid studies was perform at 37 week and the resolution of the pregnancy was when DO to 650 nm showed fetal lung maturity. It was found a correlation among the DO to 650 nm of 20 and absence of RDS in 130 cases (true positive); there were seven cases with immaturity results by DO that they did not express RDS (false negative) and six cases with results that showed immaturity by DO and there were manifestations of RDS (true negative). We did not find results of false positive. The frequency of RDS was of 4.9% with a positive predictive value of the 100% an negative predictive value of 46%, a specificity of 100% and a sensitivity of 94%. An interesting finding was the fact that six cases true negative cases had poor maternal metabolic control of different degrees. For our results can be deduced that DO to 650 nm with standard of .20 it is reliable for the diagnosis of fetal lung maturity in the pregnancies complicated with Diabetes Mellitus, in addition to be an easy elaboration test and low cost.

Female↗
PubMed1997

Sequential changes of energy metabolism and mitochondrial function in myocardial infarction induced by isoproterenol in rats: a long-term and integrative study.

Acute myocardial infarction is the second cause of mortality in most countries, therefore, it is important to know the evolution and sequence of the physiological and biochemical changes involved in this pathology. This study attempts to integrate these changes and to correlate them in a long-term model (96 h) of isoproterenol-induced myocardial cell damage in the rat. We achieved an infarct-like damage in the apex region of the left ventricle, occurring 12-24 h after isoproterenol administration. The lesion was defined by histological criteria, continuous telemetric ECG recordings, and the increase in serum marker enzymes, specific for myocardial damage. A distinction is made among preinfarction, infarction, and postinfarction. Three minutes after drug administration, there was a 60% increase in heart rate and a lowering of blood pressure, resulting possibly in a functional ischemia. Ultrastructural changes and mitochondrial swelling were evident from the first hour of treatment, but functional alterations in isolated mitochondria, such as decreases in oxygen consumption, respiratory quotient, ATP synthesis, and membrane potential, were noticed only 6 h after drug administration and lasted until 72 h later. Mitochondrial proteins decreased after 3 h of treatment, reaching almost a 50% diminution, which was maintained during the whole study. An energy imbalance, reflected by a decrease in energy charge and in the creatine phosphate/creatine ratio, was observed after 30 min of treatment; however, ATP and total adenine nucleotides diminished clearly only after 3 h of treatment. All these alterations reached a maximum at the onset of infarction and were accompanied by damage to the myocardial function, drastically decreasing left ventricular pressure and shortening the atrioventricular interval. During postinfarction, a partial recovery of energy charge, creatine phosphate/creatine ratio, membrane potential, and myocardial function occurred, but not of mitochondrial oxygen consumption, rate of ATP synthesis, total adenine nucleotides, or mitochondrial proteins. Interesting correlations of the sequential changes in heart and mitochondrial functions with energy metabolism were obtained at different stages of the isoproterenol-induced cardiotoxicity. These correlations could be useful to study and understand the cellular events involved in this pathology.

Animals↗
PubMed1993

Biological monitoring of workers at a recently opened hazardous waste disposal site.

A health assessment was performed in a recently opened landfill for toxic waste. The site has received 14,000 tons of hazardous waste, confined in drums or deposited as bulk material, which were left outdoors for seven months. The analysis in some samples showed that the waste is rich in heavy metals, however we did not find high levels of contaminates in air or surface soil in different areas on-site. When compared to a control group, high-risk workers show higher levels of arsenic in urine and hair, and non-specific symptoms (irritability and insomnia). But among groups, we did not find statistical differences in urinary mercury, blood lead, phenol in urine, cadmium in hair or blood, sister chromatid exchange values, lymphocytes proliferation kinetics, liver function tests, and other non-specific symptoms. We considered this project as a background study for human exposure to hazardous waste, providing useful results for the future evaluation of chronic effects in the same population.

Adult↗
PubMed1983

Circadian variations of adenosine level in blood and liver and its possible physiological significance.

The role of adenosine as a possible physiological modulator was explored by measuring its concentration in different tissues during a 24-hour period. Initially the circadian variations of adenosine and other purine compounds such as inosine, hypoxanthine, uric acid and adenine nucleotides were studied in the rat blood. A daily cyclic response was observed, with low levels of adenosine from 08.00 - 20.00 h, followed by an increase from this time on. Inosine and hypoxanthine levels were elevated during the day and low at night. The uric acid changes observed indicate that the decrease in purine catabolism coincides with a decrease in inosine and hypoxanthine levels and an increase in adenosine. The blood adenine nucleotides, energy charge and phosphorylation potential remained constant during the day and showed oscillatory changes during the night. Similar studies were made in the liver, a primary source of circulating purines. Liver adenosine was high during the night while inosine and hypoxanthine remained low along the 24 hours. The results suggest that liver purine metabolism might participate in the maintenance and renewal of the blood purine pool and in the energy state of erythrocytes in vivo.

Adenosine↗