PubMed Health⌕ Search

Biomedical subjects

R López-García

Publications and source records attributed to R López-García.

8 recordsLinked to original sources
PubMed2001

Partial chemical/structural elucidation of anti-mutagenic compounds from corn.

In this study, corn fractions obtained from an isolation process of anti-mutagenic factors in our previous research work (Burgos-Hernández et al., 2001), were subjected to several analyses for chemical/structural elucidation. The anti-mutagenic activity of these fractions was tested against aflatoxin B(1) (AFB(1)) and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), a mutagen that does not require bioactivation. Two concentrations of this agent in the corn fractions were tested for anti-mutagenicity in the Salmonella/microsomal mutagenicity assay, using tester strain TA100 with no metabolic activation. Corn fractions tested showed evidence of anti-mutagenic activity by producing a dose-response type of relationship between a constant amount of MNNG and several concentrations of tested corn fraction. Five different varieties of yellow corn were tested in order to determine if the anti-mutagenic factors were intrinsic to corn. Variety of the corn did not show an effect on the reduction of the mutagenic potential of AFB(1) suggesting that anti-mutagenic compounds are intrinsic to corn. Four corn fractions, previously obtained after the isolation process were analyzed by MALDI-MS and GC-MS. MALDI-MS showed the presence of two groups of molecules or molecular fragments. The molecular mass of one group ranged from 250 to 370 m/z, the other ranged from 540 to 640 m/z. GC-MS identified linoleic acid as one of the compounds responsible for the anti-mutagenic activity present in corn.

Aflatoxin B1↗
PubMed2001

Anti-mutagenic compounds from corn.

In previous studies with aflatoxin-contaminated corn an uncharacteristic response for AFB1 in the Salmonella/microsomal mutagenicity assay (Ames test) was observed and the presence of anti-aflatoxin factors in the corn was suggested. In the current study, corn was extracted and fractionated using thin layer chromatography (TLC) using different developing solvent systems and the Ames test was used to monitor for anti-mutagenic activity in the corn fractions. Both Salmonella tester strains TA98 and TA100 with metabolic activation (S9) were used. Several corn fractions, at different stages in the isolation and purification process, showed anti-mutagenic dose-responses when exposed to pure AFB1. Corti extracts were non-toxic to the tester strains and TLC fractions that showed the best anti-mutagenic dose-responses were selected for further partial characterization analyses.

Aflatoxin B1↗
PubMed1996

Reduction of risks associated with fumonisin contamination in corn.

Fumonisins, produced by Fusarium moniliforme, have been recognized as an important group of chemicals which cause health risks in domestic animals and humans. Decontamination procedures for fumonisin B1 (FB1) were evaluated to determine chemical modification and reduction in toxic/carcinogenic potentials. Ammoniation, a procedure used for decontamination of aflatoxins, yielded a 79% reduction in FB1 levels in naturally contaminated corn. Authentic FB1 and FB1-contaminated corn were exposed to alternative treatments containing various combinations of Ca(OH)2, NaHCO3, and H2O2 simulating a modified nixtamalization procedure. Treatments also included NH4Cl alone or in combination with H2O2 or horseradish peroxidase. The brine shrimp assay (Artemia spp.) was used to monitor toxicity of reaction products and the Salmonella/microsomal mutagenicity assay, using tester strains TA-100 and TA-102, was used to evaluate mutagenicity. Treatments of FB1-contaminated corn simulating modified nixtamalization (Ca(OH)2 alone or with Na-HCO3 + H2O2) gave 100% reduction of FB1 and reduced brine shrimp toxicity by ca. 40%. The positive mutagenic potential (without S-9) for extracts of corn naturally contaminated with FB1 was eliminated following exposure to modified nixtamalization. Reaction products formed when pure FB1 was treated with Ca(OH)2 and H2O2/NaHCO3 were inhibitory to Bacillus cereus, B. subtilis, and B. megaterium. No inhibitory potential was evident for contaminated corn extracts following the chemical treatments.

Animals↗
PubMed1989

[Clinical characterization of a sample of newborns at risk of presenting with an altered neurologic evaluation].

Being the Prachtl's Neurological Sieve a systematic condense analysis of neurologic screening which allows to establish a normal or suspicious neurologic condition at a sensibility of 0.85, and specificity of 0.77 with a predictive value of 0.78 (in our experience), we take it as an axis variable capable to discriminate among the population with and without risk of neurologic injury or sequela. Thirty-five newborn infants with an Apgar score at birth equal or below 6, were taken into study for the purpose of featuring the group of neonates on risk to show an altered neurologic evaluation. The study was held under the hypothesis that: low Apgar score, and morbidity and mortality risk index, need to be complemented with hospital outcome (Casaer) and the estimation of factors affecting physical and mental development (Eggermont), in order to be able to feature those neonates in risk for developing a neurologic injury or sequela. Findings showed that Prechtl's Neurological Sieve is directly influenced by the magnitude of recovery from the one to five minutes Apgar Score, by the Casaer's first or initial score and by the Eggermont's assessment items. It is also related in an indirect way to the birth weight, the gestational age, the morbidity and mortality risk index, the 1 and 5 minutes Apgar score and the final or discharge Casaer evaluation.

Apgar Score↗
PubMedDate not supplied

[Chorionic gonadotropin (beta-HCG) in the amniotic fluid in normal pregnant women].

Human chorionic gonadotropin beta subunit (beta-HCG) was measured in amniotic fluid and radioimmunoassay levels compared with those obtained in plasma from normal pregnant women. Amniotic beta-HCG exhibited a secretory pattern similar to that seen in the plasma compartment. Nonetheless amniotic beta-HCG had an elevation peak later than its plasma counterpart, with a progressive decrease that persisted throughout gestation without reaching a nadir as it occurred in plasma. Such a pattern of HCG production contained in the amnion is compatible with an HCG conformation released by the syncytiotrophoblast.

Amniotic Fluid↗