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Biomedical subjects

A Duran

Publications and source records attributed to A Duran.

At least 19 recordsLinked to original sources
PubMed2006

Antimicrobial and general toxicity activities of Gymnosperma glutinosum: a comparative study.

Gymnosperma glutinosum (Spreng.) Less (Asteraceae) is an important, and an effective herbal medicine which is wide used for the treatment of diarrhoea in Mexico. We examined and compared the antibacterial and antifungal activities through the dilution method and for general toxicity activity by the brine shrimp lethality assay of two samples of Gymnosperma glutinosum from two localities of Mexico: San Rafael-Coxcatlan (Puebla State) and Tepeji del Rio (Hidalgo State). In addition, two bioactive compounds (-)-17-hydroxy-neo-clerod-3-en-15-oic acid (1) and 5,7-dihydroxy-3,6,8,2',4',5'-hexamethoxyflavone (2) were isolated. From the hexane extract from both places was obtained a MeOH partition M(2). M(2) of Tepeji del Rio showed the least MICs (<125 microg/ml) in the majority of the bacterial strains. Sarcina lutea was the most sensitive bacteria (MIC< 125 microg/ml). The hexane extract of both localities showed antifungal activity against all tested fungi. San Rafael's hexane extract was significant more activity than Tepeji del Rio. Aspergillus niger (IC(50)=23.79 microg/ml) and Trichophyton mentagrophytes (IC(50)=90.25 microg/ml) were the more sensitive fungus strains. The strongest general toxicity activity was observed with the M(2) partition from Tepeji del Rio (LC(50)=503.7 microg/ml). The results obtained in this investigation, showed differences between the antimicrobial activities of the samples of plants collected in San Rafael (Puebla) and Tepeji del Rio (Hidalgo).

Animals↗
PubMed2006

A sequential injection electronic tongue employing the transient response from potentiometric sensors for anion multidetermination.

Intelligent and automatic systems based on arrays of non-specific-response chemical sensors were recently developed in our laboratory. For multidetermination applications, the normal choice is an array of potentiometric sensors to generate the signal, and an artificial neural network (ANN) correctly trained to obtain the calibration model. As a great amount of information is required for the proper modelling, we proposed its automated generation by using the sequential injection analysis (SIA) technique. First signals used were steady-state: the equilibrium signal after a step-change in concentration. We have now adapted our procedures to record the transient response corresponding to a sample step. The novelty in this approach is therefore the use of the dynamic components of the signal in order to better discriminate or differentiate a sample. In the developed electronic tongue systems, detection is carried out by using a sensor array formed by five potentiometric sensors based on PVC membranes. For the developed application we employed two different chloride-selective sensors, two nitrate-selective sensors and one generic response sensor. As the amount of raw data (fivefold recordings corresponding to the five sensors) is excessive for an ANN, some feature extraction step prior to the modelling was needed. In order to attain substantial data reduction and noise filtering, the data obtained were fitted with orthonormal Legendre polynomials. In this case, a third-degree Legendre polynomial was shown to be sufficient to fit the data. The coefficients of these polynomials were the input information fed into the ANN used to model the concentrations of the determined species (Cl-, NO3- and HCO3-). Best results were obtained by using a backpropagation neural network trained with the Bayesian regularisation algorithm; the net had a single hidden layer containing three neurons with the tansig transfer function. The results obtained from the time-dependent response were compared with those obtained from steady-state conditions, showing the former superior performance. Finally, the method was applied for determining anions in synthetic samples and real water samples, where a satisfactory comparison was also achieved.

Algorithms↗
PubMed2006

The RIM101 pathway contributes to yeast cell wall assembly and its function becomes essential in the absence of mitogen-activated protein kinase Slt2p.

The Saccharomyces cerevisiae ynl294cDelta (rim21Delta) mutant was identified in our lab owing to its moderate resistance to calcofluor, although it also displayed all of the phenotypic traits associated with its function as the putative sensor (Rim21p) of the RIM101 pathway. rim21Delta also showed moderate hypersensitivity to sodium dodecyl sulfate, caffeine, and zymolyase, and the cell wall compensatory response in this mutant was very poor, as indicated by the almost complete absence of Slt2 phosphorylation and the modest increase in chitin synthesis after calcofluor treatment. However, the cell integrity pathway appeared functional after caffeine treatment or thermal stress. rim21Delta and rim101Delta mutant strains shared all of the cell-wall-associated phenotypes, which were reverted by the expression of Rim101-531p, the constitutively active form of this transcription factor. Therefore, the absence of a functional RIM101 pathway leads to cell wall defects. rim21Delta, as well as rim101Delta, was synthetic lethal with slt2Delta, a synthetic defect alleviated by osmotic stabilization of the media. The double mutants grown in osmotically stabilized media were extremely hypersensitive to zymolyase and showed thicker cell walls, with poorly defined mannoprotein layers. In contrast, rim21Delta rlm1Delta and rim101Delta rlm1Delta double mutants were fully viable. Taken together, these results show that the RIM101 pathway participates directly in cell wall assembly and that it acts in parallel with the protein kinase C pathway (PKC) in this process independently of the transcriptional effect of the compensatory response mediated by this route. In addition, these results provide new experimental evidence of the direct involvement of the PKC signal transduction pathway through the Sltp2 kinase in the construction of yeast cell walls.

Cell Wall↗
PubMed2005

Informant consensus factor and antibacterial activity of the medicinal plants used by the people of San Rafael Coxcatlán, Puebla, México.

Using ethnobotanical techniques, the medicinal flora used by the inhabitants of San Rafael Coxcatlán, Puebla was determined. During the field work, two types of interviews were applied (free listing and semi-structured) to 60 informants, who supplied consistent information concerning the use of 46 species of medicinal plants. Further analysis showed 13 categories of different medicinal use. An informant consensus factor was calculated and 16 species were selected due to their utilization in the treatment of diseases of possible bacterial origin. Of these 16 plants, sequential extractions were made with hexane, ethyl acetate and methanol. The obtained extracts were used to assess their antibacterial activity against 14 bacterial strains; 75% of the plants presented antibacterial activity. The medicinal species Jatropha neopauciflora Pax (Euphorbiaceae) and Juliania adstringens (Schldl.) Schldl. (Julianiaceae) were those that showed the biggest activity. Moreover, these species also had the highest informant consensus factor values.

Anti-Bacterial Agents↗
PubMed2004

Quantitative determination of rofecoxib in pharmaceutical preparations.

Rofecoxib was assayed by UV spectrophotometry and HPLC, the concentration ranges were 2-30 microg x ml(-1) and 5-50 microg x ml(-1), respectively. The results, obtained by the two methods in pharmaceutical preparations were compared of each other. There were no significant differences between the mean values and the precisions.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Ethnobotany and antibacterial activity of some plants used in traditional medicine of Zapotitlán de las Salinas, Puebla (México).

The village of Zapotitlán de las Salinas is situated in the Valley of Tehuacán-Cuicatlán, Puebla, Mexico. Plant species used by the local inhabitants to treat gastrointestinal diseases were identified using ethnobotanical, ethnographic and taxonomic methods. Out of 119 interviews, 44 plant species were registered, of which the following are the most frequently used (listed in descending order): Lippia graveolens H.B. et K. (Verbenaceae), Lantana achyranthifolia Desf. (Verbenaceae), Turnera diffusa (Willd.) ex Schult. (Turneraceae), Lippia oaxacana Rob. et Greenm. (Verbenaceae), Gymnolaena oaxacana (Greenm.) Rydb. (Asteraceae), Cordia curassavica (Jacq.) Roem. et Schult. (Boraginaceae), Lantana camara L. (Verbenaceae) and Acalypha hederacea Torrey (Euphorbiaceae). From these plants, hexane, chloroform and ethanol extracts were prepared in order to assess their antibacterial activity against 14 bacterial strains causing the most common gastrointestinal diseases in Mexican population. All hexane extracts showed antibacterial activity against Gram-positive and Gram-negative bacteria. There is a correlation between the frequency of mention (of plant use) and the antibacterial activity. In conclusion, the knowledge of plants most frequently used for gastrointestinal infections in Zapotitlán de las Salinas is supported by scientific rationale.

Anti-Bacterial Agents↗
PubMed2002

Suitability of FISH painting techniques for the detection of partial-body irradiations for biological dosimetry.

Peripheral blood was irradiated with 2, 3, 4 or 5 Gy of X rays and was mixed with nonirradiated blood at five different dilutions to simulate partial-body irradiations. Analysis by FISH was performed using whole-chromosome painting probes for chromosomes 1, 4 and 11 in combination with a pancentromeric probe. Chromosome aberrations affecting the painted fraction were classified according to the PAINT nomenclature; other unstable aberrations affecting the unpainted material were also recorded. To evaluate the suitability of painting for dose assessment in partial-body irradiations, the ability of the u test and a proposed s test to detect the expected overdispersion and the similarity between the real doses and the doses estimated using Dolphin's approach were considered. For short-term biodosimetry, compared with solid-stained dicentric analyses, the suitability of FISH painting techniques for the detection of partial-body exposures is reduced, because of the decrease in the frequency of aberrations detected by FISH and in the number of cells with two or more aberrations. For reconstruction of past doses, when only complete apparently simple translocations in cells free of unstable aberrations were considered, the detection of the overdispersion and the accuracy of dose estimations were dramatically reduced. In a partial-body exposure, as the original dose increased, the whole-body dose estimated a long time after irradiation would tend to be lower, and the difference from the original dose would tend to be greater.

Adult↗
PubMed2001

Targeted disruption of the zetaPKC gene results in the impairment of the NF-kappaB pathway.

Here we have addressed the role that zetaPKC plays in NF-kappaB activation using mice in which this kinase was inactivated by homologous recombination. These mice, although grossly normal, showed phenotypic alterations in secondary lymphoid organs reminiscent of those of the TNF receptor-1 and of the lymphotoxin-beta receptor gene-deficient mice. The lack of zetaPKC in embryonic fibroblasts (EFs) severely impairs kappaB-dependent transcriptional activity as well as cytokine-induced phosphorylation of p65. Also, a cytokine-inducible interaction of zetaPKC with p65 was detected which requires the previous degradation of IkappaB. Although in zetaPKC-/- EFs this kinase is not necessary for IKK activation, in lung, which abundantly expresses zetaPKC, IKK activation is inhibited.

Acetylcysteine↗
PubMed2000

Cognitive organization of favorable and unfavorable beliefs about performing a behavior.

Intentions to perform behaviors are influenced by beliefs about their consequences, but researchers have not addressed how such beliefs are cognitively organized. In 3 experiments, the authors tested the hypothesis that beliefs are organized according to whether they are favorable or unfavorable in regard to performing a behavior. In Experiment 1, a group of U.S. students first read a list of beliefs favorable and unfavorable to going to a vacation resort and then listed their beliefs about condom use. In Experiment 2, another group of U.S. students listed their beliefs about condom use. In Experiment 3, a 3rd group of U.S. students listed their beliefs about a novel behavior (asking the experimenter for candy). The results of all 3 experiments were consistent with the hypothesis that people cognitively organize their beliefs according to whether they are favorable or unfavorable to the behavior in question.

Attitude↗
PubMed2000

Chitin synthesis in a gas1 mutant of Saccharomyces cerevisiae.

The existence of a compensatory mechanism in response to cell wall damage has been proposed in yeast cells. The increase of chitin accumulation is part of this response. In order to study the mechanism of the stress-related chitin synthesis, we tested chitin synthase I (CSI), CSII, and CSIII in vitro activities in the cell-wall-defective mutant gas1 delta. CSI activity increased twofold with respect to the control, a finding in agreement with an increase in the expression of the CHS1 gene. However, deletion of the CHS1 gene did not affect the phenotype of the gas1 delta mutant and only slightly reduced the chitin content. Interestingly, in chs1 gas1 double mutants the lysed-bud phenotype, typical of chs1 null mutant, was suppressed, although in gas1 cells there was no reduction in chitinase activity. CHS3 expression was not affected in the gas1 mutant. Deletion of the CHS3 gene severely compromised the phenotype of gas1 cells, despite the fact that CSIII activity, assayed in membrane fractions, did not change. Furthermore, in chs3 gas1 cells the chitin level was about 10% that of gas1 cells. Thus, CSIII is the enzyme responsible for the hyperaccumulation of chitin in response to cell wall stress. However, the level of enzyme or the in vitro CSIII activity does not change. This result suggests that an interaction with a regulatory molecule or a posttranslational modification, which is not preserved during membrane fractionation, could be essential in vivo for the stress-induced synthesis of chitin.

Cell Membrane Permeability↗
PubMed1999

Randomized, community-based trial of the effect of zinc supplementation, with and without other micronutrients, on the duration of persistent childhood diarrhea in Lima, Peru.

OBJECTIVE: To determine whether supplemental zinc, with or without additional micronutrients, affects the severity and duration of persistent childhood diarrhea and the rate of nutritional recovery. DESIGN: The study was a community-based, double-blind, randomized trial implemented in a shanty town in Lima, Peru. Children aged 6 to 36 months with persistent (>/=14 days) diarrhea received daily, for 2 weeks, a placebo (group P, n = 136) or a supplement of 20 mg of zinc, either with (group Z+VM, n = 137) or without (group Z, n = 139) additional vitamins and minerals. Symptoms of illness were recorded daily, and biochemical and anthropometric assessments were completed at baseline and on day 15. RESULTS: The treatment groups were similar at baseline with regard to the characteristics of the presenting episode, anthropometric data, and plasma zinc concentration. The children consumed, on average, 95% (group P), 94% (group Z), or 88% (group Z+VM) of the supplement (P <.001). The plasma zinc concentration did not change significantly from baseline to day 15 in group P (4 microg/dL) but increased by 38 microg/dL in group Z and 14 microg/dL in group Z+VM. The median duration of diarrhea after starting treatment was 1 day; among children who continued to have diarrhea, there was a significant effect of treatment on diarrheal duration (P =.04, analysis of covariance). Specifically, the duration of illness was significantly reduced by 28% in children in group Z (P =.01) and by 33% in girls in group Z+VM (P =.04). There were no differences in the severity of the episode by treatment group. CONCLUSION: There was a significant reduction in the duration of persistent diarrhea in selected subgroups of zinc-supplemented ambulatory patients in this population.

Analysis of Variance↗
PubMed1999

Schizosaccharomyces pombe protein kinase C homologues, pck1p and pck2p, are targets of rho1p and rho2p and differentially regulate cell integrity.

Schizosaccharomyces pombe rho1(+) is required for maintenance of cell integrity and polarization of the actin cytoskeleton. However, no other effector besides the (1,3)beta-D-glucan synthase enzyme has been identified in S. pombe. We have further investigated if rho1(+ )signalling could be also mediated by the two protein kinase C homologues, pck1p and pck2p. We show in this study that both kinases interact with rho1p and rho2p only when bound to GTP, as most GTPase effectors do. Interestingly, the interaction was mapped in a different part of the proteins than in Saccharomyces cerevisiae Pkc1p. Thus, active rho1p binds to the amino-terminal region of the pcks where two HR1 motifs are located, and binding to the GTPase dramatically stabilizes the kinases. Detailed biochemical analysis suggests that pck2p is more important in the regulation of the enzyme (1-3)beta-D-glucan synthase. Thus, overexpression of pck2(+), but not pck1(+), caused a general increase in cell wall biosynthesis, mainly in beta-glucan, and (1-3)beta-D-glucan synthase activity was considerably augmented. When this activity was separated into soluble and membrane fractions and reconstituted, the increase caused by pck2(+) overexpression was exclusively detected in the membrane component. We also show that both protein kinase C homologues are required for the maintenance of cell integrity. pck1delta and pck2delta strains present a number of defects related to the cell wall, indicating that this structure might be co-ordinately regulated by both kinases. In addition, pck2p, but not pck1p, seems to be involved in keeping cell polarity. Genetic evidence indicates that both pck1(+) and pck2(+) interact with cps1(+) and gls2(+), two genes similar to S. cerevisiae FKS1 and FKS2 that encode membrane subunits of the (1-3)beta-D-glucan synthase. pck1(+ )also showed a genetic interaction with ras1(+) and ral1(+) suggesting the existence of a functional link between both signalling pathways.

Amino Acid Sequence↗
PubMed1998

Molecular analysis of Chs3p participation in chitin synthase III activity.

Chitin is a minor but essential component of the cell wall of Saccharomyces cerevisiae, with functions in septum formation in the vegetative life cycle and also in conjugation and spore cell-wall synthesis in the sexual cycle. Of the three chitin synthases present in yeast, chitin synthase III (CSIII) is responsible for the synthesis of most of the chitin found in the cell, including a chitin ring at early budding, chitin interspersed in the cell wall, and chitin laid down during the sexual cycle. We have tagged Chs3p, the putative catalytic subunit of CSIII, with the immunoreactive epitope of influenza virus hemagglutinin to follow expression of the protein. Little correlation was found between the levels of transcription and translation of Chs3p and in vivo function, supporting our previous conclusion that regulation of CSIII occurs at the posttranslational level. To identify possible regions of the protein involved in catalysis or regulation, mutations were generated in the QRRRW 'signature sequence' of chitin synthases. Arginine residue mutations in Chs3p, and in Chs1p and Chs2p, resulted in a loss of both function in vivo and enzymatic activity. Mutations in a serine residue adjacent to glutamine in Chs3p caused loss of function in vivo with a moderate decrease in CSIII activity, suggesting a regulatory role for the serine residue in chitin biosynthesis. Several truncations in the unique hydrophilic carboxy-terminal region of Chs3p identified a sequence of about 25 amino acids that is required for both function and in vitro activity. Since this region is not present in Chs1 or Chs2, it may be involved in the specific regulation of CSIII.

Benzenesulfonates↗
PubMed1998

Characterization of the geranylgeranyl transferase type I from Schizosaccharomyces pombe.

The Schizosaccharomyces pombe cwg2+ gene encodes the beta-subunit of geranylgeranyl transferase I (GGTase I), which participates in the post-translational C-terminal modification of several small GTPases, allowing their targeting to the membrane. Using the two-hybrid system, we have identified the cwp1+ gene that encodes the alpha-subunit of the GGTase I. cwp1p interaction with cwg2p was mapped to amino acids 1-244 or 137-294 but was not restricted to amino acids 137-244. The genomic cwp1+ was isolated and sequenced. It has two putative open reading frames of 677 and 218 bp, separated by a 51 bp intron. The predicted amino acid sequence shows significant similarity to GGTase I alpha-subunits from different species. However, complementation of Saccharomyces cerevisiae ram2-1 mutant by overexpressing the cwp1+ gene was not possible. Expression of both cwg2+ and cwp1+ in Escherichia coli allowed 'in vitro' reconstitution of the GGTase I activity. S. pombe cells expressing the mutant enzyme containing the cwg2-1 mutation do not grow at 37 degrees C, but the growth defect can be suppressed by the addition of sorbitol. Actin immunostaining of the cwg2-1 mutant strain grown at 37 degrees C showed an abnormal distribution of actin patches. The cwg2-1 mutation was identified as a guanine to adenine substitution at nucleotide 604 of the coding region, originating the change A202T in the cwg2p. Deletion of the cwg2 gene is lethal; delta cwg2 spores can divide two or three times before losing viability. Most cells have aberrant morphology and septation defects. Overexpression of the rho1G15VC199R double-mutant allele in S. pombe caused loss of polarity but was not lethal and did not render the (1-3)beta-D-glucan synthase activity independent of GTP. Therefore, geranylgeranylation of rho1p is required for the appropriate function of this GTPase.

Actins↗
PubMed1998

Some tests of the distinction between attitude and perceived behavioural control.

Although perceived behavioural control has recently become a popular variable for use in predicting behaviour or intention to behave, it is far from clear that this variable is theoretically distinguishable from attitude. Consequently, we performed some tests of the distinction between attitude and perceived behavioural control. In Expt 1, using participants from an American university, the semantic differential scales that have often been used to measure attitude and perceived behavioural control were submitted to factor analyses. Consistent with the distinction, a two-factor solution resulted in the attitude and perceived behavioural control items clearly loading on different factors. Further, Expt 2 demonstrated that the attitude factor predicts behavioural beliefs and does not predict control beliefs, but the reverse is true concerning the perceived behavioural control factor. Finally, in Expts 3-5, the beliefs presumed to underlie these two variables were cluster analysed. Consistent with the distinction, and paralleling findings obtained by Trafimow & Fishbein (1995), the order in which participants wrote down their beliefs exhibited significant clustering by belief type.

Adult↗