Biomedical subjects

M Vásquez

Publications and source records attributed to M Vásquez.

At least 19 recordsLinked to original sources

PubMed1998

Metoclopramide enhances labetalol-induced antihypertensive effect during handgrip in hypertensive patients.

The effects of metoclopramide, labetalol, and metoclopramide plus labetalol treatments on baseline cardiovascular parameters and isometric handgrip-induced changes were evaluated in 11 hypertensive subjects. Although all treatments were effective in reducing resting systolic (SBP) and diastolic (DBP) blood pressures, the combination of metoclopramide and labetalol appeared to provide a greater decrease (changes in SBP/DBP: 15/11 mm Hg, P < 0.05; from 149 +/- 4/95 +/- 4 mm Hg to 134 +/- 5/84 +/- 3 mm Hg) than did labetalol alone (changes in SBP/DBP: 10/9 mm Hg, P < 0.05; from 149 +/- 4/95 +/- 4 to 139 +/- 4/86 +/- 3 mm Hg). At 2 minutes, handgrip increased blood pressure on placebo (changes in SBP/DBP: 34/7 mm Hg, P < 0. 001). In the presence of metoclopramide and metoclopramide plus labetalol, however, handgrip induced lesser increases in blood pressure (changes in SBP/DBP: 23/7 mm Hg, P < 0.01, and 18/4 mm Hg, P < 0.01, for metoclopramide and metoclopramide plus labetalol treatments). We conclude that (1) metoclopramide lowers blood pressure in hypertensive patients; (2) metoclopramide attenuates blood pressure response to isometric handgrip; and (3) both compounds, labetalol and metoclopramide, seem to have a pharmacologic interaction concerning blood pressure decrease. A clinical significance is suggested for the metoclopramide effect.

Antihypertensive Agents↗

PubMed1997

[Adiposity and fat distribution in preschool children from low socioeconomic levels in Caracas].

Epidemiological studies suggest that body fat distribution in adults is associated with chronical nontransmissible diseases, less is known during the growing years. The current study was undertaken to explore the relationship between level of fatness, fat patterning and some socioenvironmental variables in a group of 449 children aged 3 to 6, living in Caracas, who belong to the poorest Venezuelan socio-economic stratum. Data was analyzed taking nutritional status (weight-for-age), an index of socioeconomic conditions (ICSA), sex and age, as control variables. Using a multivariate analysis we derived first, two groups of households (G1 and G2) as determined by socioeconomic variables, to which principal component analysis was applied to elicited fatness and relative fat patterning through six skinfolds. First component identify level of adiposity, second extremity/trunk fatness, and third upper/lower pattern. Comparison of normal children with those of low weight-for-age showed differences in adiposity and in the upper/lower patterning as detected by the skinfolds involved in the differences: subscapular (-0.53) and supraspinale (0.32) in children with low weight-for-age; triceps (-0.46) and thigh (0.29) in those classified as normal. We found that gender, nutritional condition, environmental variables and age, were significant predictors of the differences in adiposity level; while age and households conditions, appear to be related to upper/lower patterning. The data equally suggests that body fat is more centrally distributed in boys with low weight-for-age. Since these patterns are indicators of risk in the ongoing years, we call tha attention about environmental circumstances.

Adipose Tissue↗

PubMed1996

Modeling side-chain conformation.

Over the past few years, a number of methods for the calculation of side-chain conformations in proteins have been described. More recent studies have considered the effect of combinatorial packing, derivations from idealized rotameric structures and, to a limited extent, backbone flexibility on the quality and efficiency of calculations of protein side-chain conformation. Although further work is needed to address the issue of backbone displacements, the recent progress solves the packing problem to a significant degree. This opens the way for fruitful incorporation of these methods into general procedures for homology modeling and studies of ligand-protein interactions.

Computer Simulation↗

PubMed1995

Cereal and nut bars, nutritional quality and storage stability.

Six snack-type bars were manufactured, to contain oat and wheat germ and two different walnut levels, agglutinated with natural sweeteners and fats. Two bars also contained toasted amaranth with brown sugar cover and wheat extrudate, while two others, contained puffed instead of toasted amaranth. Water activity (Aw) and moisture were determined in the manufactured products. Quality and sensory evaluation and proximate analysis were carried out on the bars containing highest levels of walnuts (18%). The caloric contribution of the bars was computed by Atwater methods. The nutritional quality of the bars was determined by means of the Protein Efficiency Ratio (PER) and Net Protein Ratio (NPR), and the results were used to obtain relative PER and relative NPR. Samples of the latter bars were kept under accelerated storage for 15 days at 37 degrees C and analyzed every 5 days to determine their Aw, moisture, peroxide and sensory acceptability. The drying time for the cereal - and walnut - based bars was 45 min at 120 degrees C. All bars presented a good fiber supply and the CN1 bar, containing only oat, wheat germ and walnut, had the greatest protein content. In the sensory evaluation, the walnut level with the greatest preference was 18%. PER and NPR values of the bars did not differ significantly showing values approximately 86% that of the casein value. During storage, the moisture and Aw decreased in all the bars. Peroxides remained within the acceptable ranges; acceptability based on sensory evaluation remained best in the bar with toasted amaranth.(ABSTRACT TRUNCATED AT 250 WORDS)

Amaranthus↗

PubMed1994

[Cereal bars with peanut and puffed amaranthus: chemical composition and stability in accelerated storage].

Three different cereal bars, CM3A-CM3B and CM3C were prepared following the flow sheat of Escobar et al: different amount of oat, wheat germ, and puffed amaranthus were used: to stick them together, natural sweeteners and fats were added. Proximate analysis, were run on raw materials and snack bars. They were evaluated organoleptically to know their quality and acceptability. Bars were kept in accelerated storage at 37 degrees C during 15 days to know their stability. Every 5 days were measured the water activity (Aw), moisture, and peroxides development; also appearance of organoleptic randicity. Acceptability of bar CM3B was 91.67% with 0.0% of rejection; CM3A and CM3C got the same acceptability (66.67%) and 8.33% of rejection. In accelerate storage, Aw and moisture content decreased until reaching a value of 0.48 and 5.9 in the CM3B bar, respectively. Peroxide content of CM3B and CM3C increased gradually up to 12 and 17 meq/kg respectively at 15 days. Rancyd aroma appearance was not the same in the bars, CM3A and CM3B had a decreasing at 15 days, while CM3C showed an increasing at the same time. In brief, CM3B showed the best sensory quality, the higher acceptability and the greater stability in accelerated storage.

Arachis↗

PubMed1994

[Chemical and nutritional characterization of amaranthus (Amaranthus cruentus)].

Two samples of Amaranthus cruentus harvested in 1987 (sample A) and 1990 (sample B) were studied. Whole and refined flours were obtained. The whole flours contained 14.6 and 12.6% protein and 6.6 and 7.3 ether extraction, respectively. Both samples contained significant levels of Ca, P, Mg and K. Amaranth oil contained 19% palmitic acid, 3.4% stearic acid, 3.4% stearic acid, 34% oleic acid and 33% linoleic acid. Docosaenoic acid (C22:1) was present at the level of 9%. The ratio of saturated to unsaturated fatty acids was approximately 1:3. The level of crude fiber was 3.7% in the whole flours and 2.4% in the refined ones. Biological protein quality of flours was measured in the rat by the net protein ratio (NPR) method. The NPR values of the four materials tested ranged from 3.04 to 3.20 (NS), as compared with 4.08 for casein. These values are equivalent to 75-78% of the standard protein. Blends of raw wheat flour and whole amaranth flour fed to rats produced a good complementary effect between proteins, as shown by PER test. Wheat flour gave a poor PER value of 0.54. However, this figure increased with every increment of amaranth flour reaching a value of 2.15 for the blend 25:75. The PER for the amaranth diet (0:100) was 1.94 (casein 2.77). As expected, the extrusion process applied to the wheat/amaranth and corn/amaranth mixtures improved the biological quality of the protein. The wheat flour diet (100:0) gave a PER value of 1.64. Mixture 90:10 produced a low non significant increase in the protein quality.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Function of rotavirus VP3 polypeptide in viral morphogenesis.

The phenotype of the rotavirus SA-11 mutant tsB carrying a thermosensitive mutation in gene 3, which encodes VP3, was characterized further from both infected cells and purified viral particles. The mutant phenotype was initially identified as negative for in vivo double- and single-stranded RNA synthesis. Our results show that the in vitro transcriptional properties of the tsB mutant at the restrictive temperature were identical to those of the wild-type strain. Similar results were obtained with respect to the VP3-associated guanylyl-transferase activity. Analysis of viral particles made by mutant-infected cells at the restrictive temperature showed that only empty single-shelled particles were assembled. This indicates that viral morphogenesis is halted after the initial viral transcription and before RNA replication, suggesting that VP3 may be required as part of the replicase system but not for subviral particle assembly. These data suggest that such a phenotype is not due to alteration of a VP3 function related to transcription.

Capsid↗

PubMed1993

[Bioessay with brine Artemia to predict antibacterial and pharmacologic activity].

The Brine Shrimp Test (BST) is a simple and inexpensive method to test cytotoxity, to biodirect phytochemical fractionation of natural products and as a predictor for antitumor and pesticidal activity. In this work, the BST test, an antibacterial test and the rat hippocratic screening test were used on 25 plant extracts and fractions, to evaluate the correlation, if any, between the BST and the others. Preliminary results show that the BST is not a predictor of antibacterial activity nor the hippocratic screening test.

Animals↗

PubMed1992

Dissection of the combining site in a humanized anti-Tac antibody.

The genetically engineered "humanized" anti-Tac antibody (HAT) has been shown to bind the p55 chain of the human IL-2R with an affinity close to that of the murine anti-Tac. Although the HAT molecule contains all six mouse CDR, it was not known which, and to what extent, each of the CDR contributes to Ag binding. These questions were addressed by constructing a series of variant HAT antibodies, each substituting a single HAT CDR with a heterologous CDR. The association constants of the variant HAT antibodies to p55 were determined by competitive binding analysis. We find that CDR 1 and 3 of the H chain and CDR 3 of the L chain are essential for maintaining binding. The remaining three CDR appear to be involved to a lesser degree.

Amino Acid Sequence↗

PubMed1992

Nutrition and education. III. Educational achievement and food habits of Chilean elementary and high school graduates.

The objective of this study was to correlate the educational achievement (EA) of Chilean elementary and high-school graduates with their food habits. For this purpose, a random sample of 550 schoolers from the Metropolitan Area of Santiago, Chile, graduating from elementary and high school (1:1) of both sexes (1:1), from public and private schools and from high, medium and low socioeconomic status (SES) (1:1:1), was selected. Food habits were determined through a specially designed questionnaire and defined as the frequency of consumption of the food groups, expressed as days per week. The EA was established through the Achievement Evaluation Program (AEP) and Academic Aptitude Test (AAT) in elementary-and high-school graduates-, respectively. Results revealed that EA was found significantly and positively correlated with the frequency of consumption of dairy products, meat products and eggs, in both elementary and high school graduates. A significant and inverse correlation between EA and the frequency of vegetables and fruits consumption was observed in both educational levels, and with miscellaneous products, only in elementary school graduates. Food habits explained 24.4% and 16.6% of the EA variance, in elementary and high school graduates, respectively. The frequency of consumption of dairy products was the independent variable with the greatest explanatory power in EA variance (approximately above 70% of the explained variance). These results are important to consider for educational planning focused on the School Feeding Program.

Adolescent↗

PubMed1991

On the multiple-minima problem in the conformational analysis of polypeptides. V. Application of the self-consistent electrostatic field and the electrostatically driven Monte Carlo methods to bovine pancreatic trypsin inhibitor.

In connection with the accompanying paper to test various models for the hydration of polypeptides, we have explored a limited portion of the conformational energy hyperspace of the small protein bovine pancreatic trypsin inhibitor (BPTI) with the aid of two search methods developed in this laboratory. A series of low-energy conformations was obtained as a result of this study. These conformations constitute a set of local minima in the conformational energy space of the molecule as described by the ECEPP/2 (Empirical Conformational Energy Program for Peptides) potential energy function, without the inclusion of hydration. Five different initial conformations were used in this exploration: the first corresponds to an energy-refined structure based on the crystallographic coordinates (4PTI) provided by Deisenhofer and Steigemann and reported previously by Meirovitch and Scheraga. The remaining four initial conformations were obtained by using a Variable-Target-Function procedure, applied to the experimental Cartesian coordinates (5PTI) reported by Wlodawer et al. The self-consistent electrostatic field (SCEF) and the electrostatically driven Monte Carlo (EDMC) methods were used to search the conformational space. The SCEF and EDMC methodologies assume that a polypeptide or protein molecule is driven toward the native structure mainly by the action of the electrostatic interactions. Application of these methodologies led to a set of conformations (up to 50 kcal/mol lower than the starting ones) with ECEPP/2 energies lower than any of those that we had previously found. Application of both methods to the initial conformation generated from 4PTI led to a series of low-energy conformations exhibiting similar rms deviations with respect to the experimental data (4PTI) as did the starting conformation. However, statistical analysis of the runs that had started from the conformations generated by using the variable-target-function procedure (and applying the EDMC method) indicated that the rms deviations of the atomic positions of the new low-energy conformations tended to increase as the energy improved, when compared with the X-ray data from which the starting conformations had been generated. The structures with the lowest energies also had radii of gyration smaller than the experimentally observed one. These results indicated a need to include hydration in the potential function, and provided the conformations used in the accompanying paper to test various hydration models.

Animals↗

PubMed1991

Empirical solvation models can be used to differentiate native from near-native conformations of bovine pancreatic trypsin inhibitor.

Several hydration models for peptides and proteins based on solvent accessible surface area have been proposed previously. We have evaluated some of these models as well as four new ones in the context of near-native conformations of a protein. In addition, we propose an empirical site-site distance-dependent correction that can be used in conjunction with any of these models. The set of near-native structures consisted of 39 conformations of bovine pancreatic trypsin inhibitor (BPTI) each of which was a local minimum of an empirical energy function (ECEPP) in the absence of solvent. Root-mean-square (rms) deviations from the crystallographically determined structure were in the following ranges: 1.06-1.94 A for all heavy atoms, 0.77-1.36 A for all backbone heavy atoms, 0.68-1.33 A for all alpha-carbon atoms, and 1.41-2.72 A for all side-chain heavy atoms. We have found that there is considerable variation among the solvent models when evaluated in terms of concordance between the solvation free energy and the rms deviations from the crystallographically determined conformation. The solvation model for which the best concordance (0.939) with the rms deviations of the C alpha atoms was found was derived from NMR coupling constants of peptides in water combined with an exponential site-site distance dependence of the potential of mean force. Our results indicate that solvation free energy parameters derived from nonpeptide free energies of hydration may not be transferrable to peptides. Parameters derived from peptide and protein data may be more applicable to conformational analysis of proteins. A general approach to derive parameters for free energy of hydration from ensemble-averaged properties of peptides in solution is described.

Animals↗

PubMed1991

Photoaffinity labeling of rotavirus VP1 with 8-azido-ATP: identification of the viral RNA polymerase.

Rotavirus single-shelled particles have several enzymatic activities that are involved with the synthesis of capped mRNAs both in vivo and in vitro. Because single-shelled particles must be structurally intact to carry out transcription, it has proven to be difficult to identify the protein within such particles that possesses associated RNA polymerase activity. One approach for characterizing the function of the individual proteins within single-shelled particles is to use nucleotide analogs to specifically label those proteins, such as the viral RNA polymerase, that have affinity for nucleotides. In this study, 8-azido-ATP (azido-ATP), a photoreactable nucleotide analog, was used to identify the viral RNA polymerase on the basis of the ability of the analog to inhibit transcription activity associated with rotavirus particles on exposure to UV light. When single-shelled particles were treated with UV light in the presence of [alpha-32P]azido-ATP, the structural protein VP1 became radiolabeled because of cross-linking of the nucleotide analog, and there was a corresponding decrease in the ability of the particles to synthesize mRNA. In parallel experiments in which single-shelled particles were not exposed to UV light, VP1 was not radiolabeled and the particles successfully used azido-ATP as a substrate for the synthesis of viral mRNAs. Taken together, these results are consistent only with the conclusion that VP1 is the rotavirus RNA-dependent RNA polymerase.

Adenosine Triphosphate↗

PubMed1991

Nutrition and education. II. Educational achievement and nutrient intake of Chilean elementary and high school graduates.

The interrelationships between educational achievement (EA) and nutrient intake were investigated in 550 Chilean adolescent schoolers graduating from elementary and high school. The random sample included schoolers from both educational levels (1:1), from public and private schools (1:1), and from high, medium, and low socioeconomic status (SES) (1:1:1). Standard procedures for 24-hour dietary recall interviews were used to collect data, and adequacy of intake was assessed by the FAO/WHO Pattern. EA was measured by means of the Achievement Evaluation Program (AEP) and Academic Aptitude Test (AAT) in elementary and high school, respectively. In elementary school graduates, results showed a significant and positive correlation between EA (AEP) and energy, protein, riboflavin, ascorbic acid, calcium and vitamin A intake (Multiple r = 0.456 p less than 0.01; r2 = 0.208). The School Feeding Program beneficiaries who belonged to the low SES presented the lowest EA (AEP) together with a deficient nutrient intake, especially for energy, riboflavin, niacin, vitamin A and calcium, at the same time that they registered the lowest values for those anthropometric parameters, indicators of past nutrition, that is to say height-for-age, weight-for-age, head circumference-for-age and a higher upper-to-lower segment ratio, as compared with non-beneficiaries from the same SES and with those from the higher strata. In high-school graduates, EA (AAT) was found to be significantly and positively correlated with protein, calcium, riboflavin and iron intake (Multiple r = 0.438 p less than 0.001; r2 = 0.192). Nevertheless, these interrelationship are strongly related to SES and sex. Results showed that educational achievement (EA) is significantly and positively associated with nutrient intake, this fact being important for educational planning related to the School Feeding Program.

Achievement↗

PubMed1991

[Sublingual captopril versus nifedipine in the treatment of hypertensive crisis].

The currently accepted drug of choice for treatment of hypertensive crisis is sublingual nifedipine. We compared the effects of sublingual captopril (25 mg) to those of nifedipine (10 mg) in 54 patients with this complication who came to the emergency room. Five min after administration of captopril, blood pressure decreased from 197.5 +/- 32.7/118.3 +/- 8.2 to 156 +/- 27.2/95.8 +/- 12.9 mmHg and heart rate decreased from 87.9 +/- 15.1 to 74.7 +/- 10.9 (p < 0.05). Blood pressure in the nifedipine group decreased from 198 +/- 27.3/120 +/- 9.8 to 147.7 +/- 17.8/86 +/- 17.9 (p < 0.05), while no change was observed in heart rate. Delayed measurements showed lower diastolic pressures at 60 and 75 min and lower systolic pressure at 120 min in the nifedipine group (p < 0.054). Few and not significantly different side effects were observed with both drugs. Thus, sublingual captopril is useful for treatment of hypertensive crisis.

Administration, Sublingual↗

PubMed1991

[Vibration and acoustic stimulation during labor with external monitoring. Pathology of fetal heart rate].

Vibratory acoustic stimulation was done in patients with an abnormal fetal heart rate tracing in external continuous electronic monitoring during labor, correlating with Apgar score, meconium staining and umbilical cord pH, describing a 83.3% sensitivity, 81.3% specificity and 62.5% positive predictive value. The authors recommend the use of vibratory acoustic stimulation in those cases with an abnormal fetal heart rate tracing in external continuous electronic monitoring, when we can not install internal electronic monitoring or obtain a fetal blood pH on assessment of fetal well-being.

Acoustic Stimulation↗

PubMed1990

Helix-coil stability constants for the naturally occurring amino acids in water. XXIII. Proline parameters from random poly (hydroxybutylglutamine-co-L-proline).

Water-soluble random copolymers containing L-proline and N5-(4-hydroxybutyl)-L-glutamine were synthesized by copolymerization of the tripeptides H-L-Glu(OBzl)-L-Glu(OBzl)-L-Glu(OBzl)-OH and H-L-Glu(OBzl)-L-Pro-L-Glu(OBzl)-OH, using benzotriazolyl-N-oxy-tris(dimethylamino)-phosphonium hexafluorophosphate as condensing reagent, and subsequent aminolysis of the Bzl ester groups with 4-amino-1-butanol. These copolymers were found to contain significant amounts of N5-(4-hydroxybutyl)-D-glutamine, thus requiring the synthesis of a binary copolymer containing only D- and L-N5-(4-hydroxybutyl)glutamine residues in order to evaluate the possible effects of the D-residues on the conformational properties of poly(hydroxybutylglutamine-co-L-proline). The different copolymers were fractionated, and their thermally induced helix-coil transition curves were obtained in water at neutral pH. When proper corrections were applied for the helix-destabilizing properties of N5-(4-hydroxybutyl)-D-glutamine, the Zimm-Bragg parameters sigma and s for L-proline could be deduced from the melting curves of poly(hydroxybutylglutamine-co-L-proline). The results indicate that L-proline acts as a very strong helix breaker over the entire temperature range from 0 to 60 degrees C.

Amino Acid Sequence↗

PubMed1989

High-resolution NMR studies of fibrinogen-like peptides in solution: structure of a thrombin-bound peptide corresponding to residues 7-16 of the A alpha chain of human fibrinogen.

The interaction of the following human fibrinogen-like peptides with bovine thrombin was studied by one- and two-dimensional NMR techniques in aqueous solution: acetyl-Phe(8)-Leu(9)-Ala(10)-Glu-(11)-Gly(12)-Gly(13)-Gly(14)-Val(15)-Ar g(16)- Gly(17)-Pro(18)-NHMe (F6), acetyl-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg(16) (tF6), acetyl-Asp(7)-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg(16)-Gly(17)-Pro- Arg(19)-Val(20)-NHMe (F8), and acetyl-Asp-Phe-Leu-Ala-Glu-Gly-Gly-Gly-Val-Arg(16) (tF8). At pH 5.3 and 25 degrees C, the Arg(16)-Gly(17) peptide bonds in both F6 and F8 were cleaved instantaneously in the presence of 0.5 mM thrombin, producing truncated peptides tF6 and tF8 and other peptide fragments. On the basis of observations of line broadening, thrombin was found to bind to the cleavage products, tF6 and tF8, of peptides F6 and F8. Peptide tF8 may have a higher affinity for thrombin than peptide tF6, as suggested by the more pronounced thrombin-induced line broadening on the proton resonances in peptide tF8. Transferred NOE (TRNOE) measurements were made of the complexes between thrombin and peptides tF6 and tF8. Medium- and long-range NOE interactions were found between the NH proton of Asp(7) and the C beta H protons of Ala(10), between the C alpha H proton of Glu(11) and the NH proton of Gly(13), and between the ring protons of Phe(8) and the C alpha H protons of Gly(14) and the C gamma H protons of Val(15). Sets of structures of the decapeptide tF8 were deduced by use of distance geometry calculations based on sequential and medium- and long-range TRNOEs from the thrombin-bound peptide. A predominant feature of these structures is the nonpolar cluster formed by the side chains of residues Phe(8), Leu(9), and Val(15) that are directly involved in binding to thrombin. This structural feature is brought about by an alpha-helical segment involving residues Phe(8)-Ala(10), followed by a multiple-turn structure involving residues Glu(11)-Val(15). These results provide an explanation for the observations that Asp(7), Phe(8), and Gly(12) are strongly conserved in mammalian fibrinogens and that the mutations of Asp(7) to Asn(7) and of Gly(12) to Val(12), result in delayed release of fibrinopeptide A, producing human bleeding disorders.

Amino Acid Sequence↗