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Biomedical subjects

M E Mora

Publications and source records attributed to M E Mora.

6 recordsLinked to original sources
PubMed1999

Exploring the conformation of bilirubins with natural and unnatural analogues: use of positional and bridged isomers of bilirubin IXalpha.

Unlike bilirubin IXalpha (1), the isomers bilirubin IXdelta (2) and neobilirubin IXbeta (3) do not require conjugation with glucuronic acid in order to be excreted. A conformational analysis employing an optimized Monte Carlo method and a mixed Monte Carlo stochastic dynamics reveals that isomer 2 exhibits a structure more closed than the well known 'ridge-tile' conformation of 1. The change in the position of both propionic acid chains causes the loss of at least four hydrogen bonds. On the other hand, the change in the configuration of the distal dipyrrinone and the blockage of the lactamic nitrogen by the presence of a bridge in isomer 3 results in an open and more elongated structure, where the chance of hydrogen bond formation in this region is obliterated. The resulting molecular models for these compounds are consistent with 1H NM R, UV-vis, and TLC data.

Animals↗
PubMed1998

Probing the conformation of bilirubins with monopropionic analogs: a biological, spectroscopic, and molecular modeling study.

The in vivo metabolism of a bilirubin analog substituted with a propionic acid chain in C8 (5) showed that it is excreted in bile conjugated with glucuronic acid, while a positional isomer substituted with a propionate in C7 (6) is excreted in bile without conjugation. A conformational analysis employing an optimized Monte Carlo method and a mixed Monte Carlo/stochastic dynamics reveals that isomer 5 adopts a 'ridge tile' conformation, stabilized by the presence of three intramolecular hydrogen bonds. On the contrary, isomer 6 exhibits a more closed structure, where impairment in the formation of at least one of the hydrogen bonds occurs. These theoretical predictions agree well with 1H NMR, UV-vis, and TLC data.

Bilirubin↗
PubMed1994

Degradation of heme IX in rats pretreated with cobaltous chloride. A study in isolated perfused liver.

The effect of the administration of cobaltous chloride on the degradation of heme IX was investigated using perfusions of isolated rat livers. The presence of biliverdin IX beta (2%) in the bile fluid of cobaltous chloride treated rats support the hypothesis of the presence of a chemical oxidation of heme IX induced by the cobalt salt. In control rats the absence of biliverdin IX beta in the bile fluid was observed. When biliverdin IX beta was added to the perfusate it was excreted in the bile fluid as bilirubin IX beta without conjugation. An increase from approximately twofold to three-fold of the total bilirubins in the bile fluids of cobaltous chloride pretreated rats in relation with control rats was observed due to heme oxygenase enhanced activity. Bilirubin IX alpha diconjugates increased ca. 15% in the bile fluids of cobaltous chloride pretreated rats, after the addition of hemin IX. The increase could reflect the presence of a new molecular form of UDP-glucuronosyltransferase, which favours the formation of bilirubin IX alpha diglucuronide and therefore its preferential excretion into the bile. In the bile fluid of the rats pretreated with cobaltous chloride, other diconjugates of bilirubin IX alpha were also detected 120 min after the addition of hemin IX to the perfusate, consisting of glucose and glucuronate (5%) and xylose and glucuronate (5%).

Animals↗
PubMed1988

Acculturation and drinking among people of Mexican descent in Mexico and the United States.

This article studies the relationships between acculturation and drinking and alcohol-related problems among people of Mexican descent in Mexico and the United States. Subjects in the United States were part of a national probability sample of the Hispanic household population 18 years of age and older. Subjects in Mexico were randomly selected from among adult residents of the city of Morelia and an adjoining rural county, Tarimbaro, both in the State of Michoacan. Both samples were interviewed using the same questionnaire. Response rates were 72% in the United States and 92% in Mexico. Results show that Mexican-American men drink more frequently than men in Michoacan, who, as a group, drink infrequently but consume more often five or more drinks at a sitting as compared with Mexican Americans. Mexican-American women have a lower rate of abstention and a higher rate of women who drink at least once a week and who consume five drinks at a sitting at least once a year than do women in Michoacan. Among men, changes in drinking seem to occur soon after coming to the United States--often within 5 years. Among women, drinking patterns are not related to length of residence in the United States. In spite of less drinking, respondents in Michoacan report more alcohol problems than do Mexican Americans.

Acculturation↗
PubMed1981

Drug use among non-students in three countries.

This paper reports a study of drug use among non-students in three countries: Mexico, Canada and India. In all three countries core items from a World Health Organization questionnaire were used. The results were generally consistent with the expectation that non-students would show greater use than students. The strongest relationship was found for cannabis (all three countries) and amphetamines (Canada and Mexico). The results indicate the need for special preventive programmes for non-students in both developing and developed countries.

Adolescent↗