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M Molina

Publications and source records attributed to M Molina.

At least 55 records · Page 3Linked to original sources
PubMed1999

Conformational structure and binding mode of glyceraldehyde-3-phosphate dehydrogenase to tRNA studied by Raman and CD spectroscopy.

Recently it has been suggested that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) play a role in nuclear tRNA export. As the structural basis of binding of GAPDH to tRNA is as yet unknown, we have employed Raman and CD spectroscopy as probes of the solution structures of GAPDH from rabbit and tRNA(Phe) from brewers yeast. Additionally, we have obtained the Raman and CD spectra of GAPDH when bound to tRNA(Phe). In the complex we find the following results: (a) The most part of the tRNA(Phe) structure is conserved, but with a slight perturbation toward a B-like form. (b) No significant changes in the secondary structure of the protein upon binding are observed. (c) The surface enhanced Raman spectra are consistent with a GAPDH-tRNA(Phe) complex molecular model that involves the insertion of TRNA(Phe) into the GAPDH tetramer groove containing the R and P axes. (d) The specific interactions that occur between GAPDH and the tRNA(Phe) involve, mainly, stacking between nucleobases and aromatic amino-acid residues, and ionic interactions of basic amino-acid residues with phosphate groups of the ribose-phosphate backbone. The above stacking interactions are also supported by the significant relatedness that we have found between an amino-acid sequence (residues 303-308) of GAPDH and RNP2 binding motifs of some RNA binding proteins.

Amino Acid Sequence↗
PubMed1999

A large-scale sonication assay for cell wall mutant analysis in yeast.

The complete yeast genome contains a large number of genes of unknown biological function. Simple, rapid and reliable specific screens are valuable tools in exploring gene function via systematic phenotypic analysis of large mutant collections. This report provides a new approach for monitoring changes in cell wall strength, based on the deleterious effects caused by ultrasound on the yeast cell surface. Sonication can thus be used for the screening of mutants affected in the architecture or stability of the cell wall, since such mutants are expected to have an altered sensitivity to this treatment compared to that of a wild-type. The experimental procedure, consisting in the quantification of damaged cells after a mild sonication treatment, by means of flow cytometry, can be applied on a large scale. The usefulness of the sonication assay as a primary screen for cell wall-related mutants is evaluated on the collection of calcofluor white-hypersensitive and -resistant mutants obtained by Lussier et al. (1997). A further phenotypic characterization of the sonication-hypersensitive mutants within the calcofluor white collection is also presented.

Benzenesulfonates↗
PubMed1999

Multi-residue analysis of N-methylcarbamate pesticides and their hydrolytic metabolites in environmental waters by use of solid-phase extraction and micellar electrokinetic chromatography.

A method for the simultaneous separation and determination of N-methylcarbamate pesticides and their hydrolytic metabolites by micellar electrokinetic chromatography (MEKC) was developed. A mixture of five pesticides (carbaryl, propuxur, carbofuran, aminocarb, and methiocarb) and their corresponding phenols was studied to optimize the separation of its components in terms of various electrophoretic parameters such as buffer type, pH and concentration, sodium dodecyl sulfate concentration, injection conditions, and applied voltage. Excellent separation of all ten analytes was achieved within about 20 min. The optimized method was used for determinations in environmental water samples. Sample volumes of 250 mL were first preconcentrated in the pesticides and metabolites by passage through a LiChrolut EN sorbent column and then further enriched by on-column stacking. Dynamic ranges of 40 ng/L - 6 microg/L, limits of detection at the nanogram-per-liter level, and relative standard deviations from 2.6 to 7.4% were obtained. The proposed method surpasses high-performance liquid chromatography (HPLC) in separation efficiency. In fact, it provides more expeditious separations and allows more flexible adjustment of the selectivity. Also, it enables the quantification for the analytes studied in this work with decreased limits of detection.

Carbamates↗
PubMed1999

[Health care networks, migration and cross-cultural adaptation in Lausanne: an action-research in progress].

In Lausanne, Switzerland, there is a growing population of migrant people of different origins. This evolving situation calls for a continuous adjustment between need and offer in terms of healthcare. Up to now, this adjustment, which involves cross-cultural adaptation processes, was based on the use of untrained interpreters. However, clinical experience shows that the use of untrained interpreters tends to keep migrant patients in an unfavourable position. This paper describes an action-research in Lausanne, which aims at the evaluation of the changes that are brought by the introduction of trained cultural mediators and interpreters (CMI) into the medical field. The paper enumerates the clinical issues that gave birth to the project and the methodological choices that were made. After discussing the first results, the authors describe how the different research stages are adapted and modified through continuous mutual influences between the field and the research process itself.

Adult↗
PubMed1999

Experimental esophagitis induced by acid and pepsin in rabbits mimicking human reflux esophagitis.

BACKGROUND & AIMS: The lack of appropriate animal models might explain the paucity of information on the mechanisms of mucosal damage and defense in reflux esophagitis. The aim of this study was to develop a model of esophagitis in rabbits mimicking human reflux esophagitis. METHODS: New Zealand white rabbits underwent surgery for placement of a plastic tube into the cervical esophagus. Acidified pepsin (AP) was intermittently perfused for different periods. Esophageal injury was assessed by macroscopic and microscopic examination, including the cell proliferation immunohistochemical parameter mib1. RESULTS: Rabbit losses (20%) were attributable mostly to postsurgical mortality and tube displacement. Perfusion of AP for 60 min/12 h or 45 min/12 h induced high-grade esophagitis by days 3 and 5, respectively, characterized by diffuse erosion/ulceration, inflammation, bleeding, and reactive epithelial changes. Perfusion of acidified pepsin for 60 min/day, especially at 30 min/12 h, induced low-grade esophagitis characterized by superficial epithelial loss, mild/absent inflammation, and epithelial reactive changes including increased cell proliferation, basal hyperplasia, and papillomatosis, which reached maximal expression by day 7. This perfusion regimen induced mucosal adaptation to damage. CONCLUSIONS: Different and highly reproducible esophageal mucosal lesions mimicking human reflux esophagitis can be induced in rabbits with repetitive acid and pepsin exposure.

Acute Disease↗
PubMed1999

Sedative actions of Ternstroemia sylvatica in the male rat.

Ternstroemia sylvatica is a plant reputed popularly to possess a anxiolytic properties but has not yet been systematically tested for such activity. The behavioral actions of T. sylvatica were examined using the open field test, the elevated plus-maze test, and the forced swim test in male rats. T. sylvatica (7.1 mg/kg and 14.2 mg/kg, i.p.) reduced ambulatory behavior in the open field test and cancelled the anti-immobility actions produced by desipramine (32 mg/kg, i.p.) in the forced swim test, as did diazepam. In the elevated plus-maze test, T. sylvatica (7.1 mg/kg, i.p.) failed to show anxiolytic actions. It is concluded that Ternstroemia sylvatica produces sedative effects rather than the attributed anxiolytic actions.

Animals↗
PubMed1999

Mimosa pudica may possess antidepressant actions in the rat.

In Mexico, aqueous extracts from dried leaves of Mimosa puolica are employed to alleviate depression. In this study, the behavioral actions of aqueous extracts of M. pudica at various concentrations were tested. Rats having received saline (0.9%; 0.30 ml; I.P.), clomipramine, desipramine or several dosages of aqueous extracts from M. pudica (ml = 2.0 mg/kg; m2 = 4.0 mg/kg; m3 = 6.0 mg/kg; m4 = 8.0 mg/kg) during a 30-day period were submitted to the forced swimming test and to the test for differential reinforcement of low rates of response at 72 sec (DRL-72s). Any possible anxiolytic action resulting from several doses (ml = 2.0 mg/kg; m2 = 4.0 mg/kg; m3 = 6.0 mg/kg; m4 = 8.0 mg/kg) of extracts of M. pudica were compared with those caused by diazepam (1.3 mg/kg, I.P.) in the elevated plus-maze test. Results showed that clomipramine (1.25 mg/kg, I.P.), desipramine (2.14 mg/kg, I.P.) and M. pudica (6.0 mg/kg and 8.0 mg/kg, I.P.) reduced immobility in the forced swimming test and increased the rate of reinforcers received in the DRL-72s test; these data suggest that M. pudica produces antidepressant effects in the rat. Diazepam increased the open-arms exploration time in the elevated plus-maze test, but M. pudica did not show any comparable action at any tested dose. M. pudica therefore produced an antide-pressant-like profile similar to two tricyclic antidepressants.

Animals↗
PubMed1999

An intervention study to enhance medication compliance in community-dwelling elderly individuals.

OBJECTIVE: To determine whether daily videotelephone or regular telephone reminders would increase the proportion of prescribed cardiac medications taken in a sample of elderly individuals who have congestive heart failure (CHF). METHODS: The authors recruited community-dwelling individuals age 65 and older who had the primary or secondary diagnosis of CHF into a randomized controlled trial of reminder calls designed to enhance medication compliance. There were three arms: a control group that received usual care; a group that received regular daily telephone call reminders; and a group that received daily videotelephone call reminders. Compliance was defined as the percent of therapeutic coverage as recorded by Medication Event Monitoring System (MEMS) caps. Subjects were recruited from 2 sources: a large urban home health care agency and a large urban ambulatory clinic of a major teaching hospital. Baseline and post-intervention MOS 36-Item Short-Form Health Survey (SF-36) scores and Minnesota Living with Heart Failure (MLHF) scores were obtained. RESULTS: There was a significant time effect during the course of the study from baseline to post-intervention (F[2,34] = 4.08, p < .05). Over time the elderly individuals who were called, either by telephone or videotelephone, showed enhanced medication compliance relative to the control group. There was a trend, but no significant difference between the two intervention groups. Both SF-36 and MLHF scores improved from baseline to post-intervention for all groups. There was no significant change in the SF-36 scores for the sample, but there was a significant change for the MLHF scores (p < .001). The control group had a significant fall off in the medication compliance rate during the course of the study, dropping from 81% to 57%. CONCLUSIONS: Telephone interventions are effective in enhancing medication compliance and may prove more cost effective than clinic visits or preparation of pre-poured pill boxes in the home. Technologic advances which enable clinicians to monitor and enhance patient medication compliance may reduce costly and distressing hospitalization for elderly individuals with CHF.

Aftercare↗
PubMed1999

Cross-induction of pyrene and phenanthrene in a Mycobacterium sp. isolated from polycyclic aromatic hydrocarbon contaminated river sediments.

A polycyclic aromatic hydrocarbon (PAH)-degrading culture enriched from contaminated river sediments and a Mycobacterium sp. isolated from the enrichment were tested to investigate the possible synergistic and antagonistic interactions affecting the degradation of pyrene in the presence of low molecular weight PAHs. The Mycobacterium sp. was able to mineralize 63% of the added pyrene when it was present as a sole source of carbon and energy. When the enrichment culture and the isolated bacterium were exposed to phenanthrene, de novo protein synthesis was not required for the rapid mineralization of pyrene, which reached 52% in chloramphenicol-treated cultures and 44% in the absence of the protein inhibitor. In the presence of chloramphenicol, < 1% of the added pyrene was mineralized by the mixed culture after exposure to anthracene and naphthalene. These compounds did not inhibit pyrene utilization when present at the same time as pyrene. Concurrent mineralization of pyrene and phenanthrene after exposure to either compound was observed. Cross-acclimation between ring classes of PAHs may be a potentially important interaction influencing the biodegradation of aromatic compounds in contaminated environments.

Biodegradation, Environmental↗
PubMed1998

The deletion of six ORFs of unknown function from Saccharomyces cerevisiae chromosome VII reveals two essential genes: YGR195w and YGR198w.

We have deleted six different ORFs of unknown function located on the right arm of Saccharomyces cerevisiae chromosome VII; namely, YGR187c/HGH1, YGR189c, YGR194c, YGR195w, YGR196c and YGR198w. No basic phenotypes could be attributed to the strains deleted in any of genes YGR187c/HGH1, YGR189c, YGR194c and YGR196c. These deletants did not show mating, sporulation or growth defects under any of the conditions tested. However, spores bearing deletions in either the YGR195w or YGR198w genes were unable to develop into macroscopical colonies. The YGR195w gene product shows significant homology with bacterial ribonuclease PH, an enzyme hitherto undescribed in yeasts, and its deletion causes a loss of viability after one to three rounds of cell division. Overexpression of this gene, using a tetracycline-regulatable promoter system, did not cause any effect on the cells. Contrary to what has been reported for prokaryotic homologs, this enzyme could play an essential role in yeast cell biology. The product encoded by the other essential ORF, YGR198w, shows no significant homology with any protein of known function in the databases. Spores bearing the deletion usually germinate and give rise to microcolonies of 50-100 non-viable cells.

Chromosomes, Fungal↗
PubMed1998

Cloning and sequence analysis of the Pichia pastoris TRP1, IPP1 and HIS3 genes.

The Pichia pastoris TRP1 and HIS3 genes were cloned by complementation of the Saccharomyces cerevisiae trip1 and his3 mutants, respectively, and their nucleotide sequence was determined. The P. pastoris TRP1 gene includes an open reading frame (ORF) of 714 nucleotides corresponding to a polypeptide of 237 amino acids whose sequence shares about 40% identity with that of TRP1 encoding proteins in other yeast species. DNA sequencing showed that an ORF of 858 nucleotides, encoding a protein of 285 amino acids with high homology to inorganic pyrophosphatases (IPP1), is located downstream of the P. pastoris TRP1 gene. Both genes converge in this chromosomal region, showing a genetic organization analogous to that found in the Kluyveromyces lactis genome. The P. pastoris HIS3 gene possesses an ORF of 675 nucleotides, encoding a polypeptide of 224 amino acids which shows 74.1% identity to the homologous S. cerevisiae protein. The hexameric consensus GCN4 binding sequence (TGACTC), characteristic of many amino acid biosynthetic genes, is present in the promoter region.

Aldose-Ketose Isomerases↗
PubMed1998

Esophageal function in achalasia: preoperative and postoperative manometric studies.

BACKGROUND/PURPOSE: Aperistalsis observed in children with achalasia may be secondary to sphincteric spasm or reflect a primary esophageal dysfunction. The aim of this study was to assess manometrically sphincteric function and esophageal motility before and after successful myotomy. METHODS: Conventional stationary and pull-through manometry were performed preoperatively in 14 patients and postoperatively in 13. Ambulatory 24-hour manometry was carried out in four and eight patients in these two groups, respectively, and the results were compared with those of 23 refluxing youngsters. RESULTS: Sphincter hypertony with lack or incompleteness of relaxation was found preoperatively in all patients, and sphincter pressure decreased dramatically after myotomy in all of them. All patients had aperistalsis preoperatively, and only a few had some primary, but weak, contractions postoperatively. Ambulatory manometry results confirmed a reduced number of motor events even during meals and only insignificant improvement of progressiveness, completeness and amplitude of waves after myotomy irrespective of the time elapsed since the procedure, the degree of recovery of esophageal caliber, and the clinical outcome. CONCLUSIONS: Motor disorders in achalasia in children are similar to those of adults with the same disease. Motor recovery is observed only in some patients, although it is never complete, and their esophagi will remain ineffective for life. Because myotomy destroys the sphincter, and motility is permanently impaired in this condition, a fundoplication must be interposed to allow long-term mucosal protection.

Adolescent↗
PubMed1998

Binding affinity independent contribution of peptide length to the stability of peptide-HLA-DR complexes in live antigen presenting cells.

The effect of peptide length on the stability of peptide-HLR-DR1 (DR1) complexes was analyzed using two peptide series of increasing length, each containing a 7mer core with five DR1-binding anchors, extended stepwise with Ala residues at the N- and C-terminus, respectively. The Ala extensions, although did not affect binding affinity, significantly increased the half lives of peptide-DR1 complexes (from 1.5 h up to 10 h) in live antigen presenting cells (APC). Flanking residues from position -2 to 0 and 8 to 11 were involved in the affinity-independent increase of complex stability. The shortest (8mer and 9mer) peptides, with in vivo half lives of <2.5 h, were unable to form stable complexes with DR1 in presence of HLA-DM (DM) molecules, and were poor competitors of antigen presentation. Longer peptides were resistant to DM-mediated unloading, and were efficient competitors of antigen presentation. Thus, DM appears to limit short peptides in establishing biologically relevant DR occupancy, despite their high binding affinity. In APC, stable complexes can form only with high affinity peptides of >9 residues, and the longevity of complexes seems to depend on full of occupation of the binding site.

Antibodies, Monoclonal↗