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Biomedical subjects

M Mendoza

Publications and source records attributed to M Mendoza.

At least 19 recordsLinked to original sources
PubMed2006

Locating and linking to medical care HIV-positive persons without a history of care: findings from the California Bridge Project.

The California Bridge Project was developed to actively locate out-of-treatment HIV-positive persons and link them to HIV care and treatment services. Three hundred and twenty five clients had never received HIV medical care. Among these clients the average time from HIV diagnosis to contact with project staff was one-and-a-half years. Nearly three-fourth of clients were persons of color and almost half were men who have sex with men (MSM). The project was effective in linking 29.2% of clients to medical care. First contact to linkage required an average of 15.4 client contacts. During these encounters project staff assessed clients' risk behaviors and physical and mental health status and addressed real or perceived barriers to care. Latinos were over two times (adjusted OR = 2.33, p=0.034) and African Americans over three times (adjusted OR = 3.69, p=0.002) more likely than whites to be linked to medical care. Success in linking persons of color to medical care may have been because the majority of project staff were persons of color who were purposely hired with characteristics similar to those of the target population. The Bridge Project demonstrates the challenges faced in attempting to link HIV-positive persons from underserved and marginalized populations to medical care.

Adult↗
PubMed2005

Dermatophytes growth curve and in vitro susceptibility test: a broth micro-titration method.

The introduction of systemic antifungal drugs which act upon different targets is the main issue of the in vivo antifungal resistance control. Different factors, such as growth curve phase, quality of the specimen, quantity of the inoculum, temperature, pH, culture medium composition, incubation duration and solvent, are believed important factors affecting minimum inhibitory concentration (MIC) value to most of the antifungal agents. We assayed an in vitro susceptibility test with 40 isolates of dermatophytes: Microsporum canis, Trichophyton rubrum, Trichophyton mentagrophytes and Epidermophyton floccosum against griseofulvin, fluconazole, itraconazole and terbinafine, using the guidelines of the M38-P document approved by the NCCLS. We determined the growth curves, to estimate the specific growth rate (mu max) and the generation time (G) of each dermatophyte, using dry weight and spectrophotometry methods. We demonstrate that, at 192 h, all fungi tested had a constant growth curve and we considered this as the optimal time for MIC determination. Terbinafine, griseofulvin and itraconazole possessed the highest antifungal activity against the four groups of dermatophytes studied. Fluconazole demonstrated no efficacy. Our MIC results differ from other authors and this difference is due to the timing of the MIC determination based on the growth curve of each fungi tested.

Antifungal Agents↗
PubMed2004

Placebo-controlled phase I/II studies of minocycline in amyotrophic lateral sclerosis.

Two double-blind, randomized, placebo-controlled feasibility trials of minocycline in ALS were conducted. In Trial 1, 19 subjects received 200 mg/day or placebo for 6 months; there were no significant differences in adverse events (AE). In Trial 2, 23 subjects received up to 400 mg/day in an 8-month crossover trial. The mean tolerated dose was 387 mg/day, there was a trend toward more gastrointestinal AE (p = 0.057), and blood urea nitrogen and liver enzymes became elevated (p < 0.05). Using these data, the authors have designed and launched a phase III trial.

Adult↗
PubMed2004

Evaluation of the presence of a thapsigargin-sensitive calcium store in trypanosomatids using Trypanosoma evansi as a model.

Ca2+ plays an important role in the regulation of several important activities in different trypanosomatids. These parasites possess a Ca2+ transport system in the endoplasmic reticulum (ER) involved in Ca2+ homeostasis, which has been reported to be insensitive to thapsigargin, a classical inhibitor of the sarcoplasmic-ER Ca2+ adenosine triphosphatase (ATPase) (SERCA) in most eukaryotic cells. However, currently there is a controversy regarding the existence of a thapsigargin-sensitive ER Ca2+ store in these parasites. Therefore, we decided to explore the effect of this inhibitor using different methodological approaches. First, we selected Trypanosoma evansi as a parasite model to warrant the homogeneity of the population because this parasite has only a single life cycle, i.e., bloodstream-form trypomastigotes. Second, we compared the thapsigargin effect on Ca2+ homeostasis by spectrophotometrical Ca2+ measurements using 3 different approaches: whole-cell populations, cells that have been permeabilized by treatment with digitonin, and intact single cells. Our results demonstrate that a low concentration of thapsigargin induces Ca2+ release from intracellular Ca2+ stores in this parasite, which can be observed independently of the method used. Furthermore, the addition of thapsigargin before or after nigericin did not abolish its effect, showing that thapsigargin acts specifically on the ER. In conclusion, our results indicate the presence of a nonmitochondrial thapsigargin-sensitive Ca2+ store in T. evansi.

Animals↗
PubMed2002

Purification of a 64 kDa antigen from Trypanosoma evansi that exhibits cross-reactivity with Trypanosoma vivax.

Trypanosoma evansi and Trypanosoma vivax are the most extensively distributed trypanosomes responsible for diseases in livestock. Western blot and indirect immunofluorescence assays revealed a high immunological cross-reaction between these two parasites. An antigen with an apparent molecular mass of 64 kDa (p64), which exhibited cross-reactivity with T. vivax, was purified to homogeneity from a Venezuelan isolate of T. evansi. This antigen is glycosylated, contains a glycosyl-phosphatidylinositol anchor and appeared to be localized through the cell except in the nucleus, indicating that it could primarily be confined to the parasite surface. These results, together with its relative abundance and apparent molecular weight, suggest that p64 probably corresponds to the soluble form of a variable surface glycoprotein from T. evansi. Anti-p64 polyclonal antibodies, raised on mice, recognized a 53 kDa polypeptide band from a Venezuelan isolate of T. vivax on Western blots. Additionally, sera obtained from naturally infected animals also recognized p64, suggesting its potential use as a diagnostic reagent. Mild acid treatment only slightly decreased the immunorecognition of p64, suggesting its potential use as a diagnostic reagent. Mild acid treatment only slightly decreased the immunorecognition of p64, demonstrating that another relevant cross-reacting epitope, different than the inositol-1,2-cyclic phosphate of the cross-reacting determinant, must exist in p64. To date, p64 represents the first antigen isolated and partially characterized from T. evansi.

Animals↗
PubMed2002

Production of culture filtrates of Sporothrix schenckii in diverse culture media.

Mycelial-form Sporothrix schenckii was studied to determine if growth in complex (Sabouraud-dextrose) or defined culture media (minimal medium, Gibco Medium 199 with and without Hepes buffer) with differing initial pH levels would affect expression of antigen components. Cultures were evaluated by continuous monitoring and serial sampling for various parameters. Great variation was seen in the protein and antigenic patterns induced by the different media. The expression of a 55 kDa component accompanied by significant acidification of the culture medium at the beginning of the stationary growth phase was notable in Sabouraud medium. In the chemically defined media, a 90 kDa component was expressed that reacted with sera from patients with sporotrichosis. The pH in these media showed little change during the different growth phases of the fungus. Among the media studied, minimal medium favored the expression of the greatest number of antigenic components. In all of the assays, the stationary growth phase appeared to be optimal for content of antigenic components. Cross reactions were not observed with any of the culture filtrates using sera from patients with other mycoses.

Culture Media↗
PubMed2001

A placebo-controlled trial of gabapentin in spinal muscular atrophy.

OBJECTIVE: To evaluate the efficacy of gabapentin in increasing muscle strength of patients with spinal muscular atrophy (SMA). BACKGROUND: Preclinical data in experimental models of motor neuron disease suggest a neuroprotective effect of gabapentin. METHODS: Gabapentin (1200 mg), or placebo, was administered three times daily in a randomized, double-blind trial for 12 months. The primary outcome measure was the average percent change from baseline, based on the measurement of strength in four muscles (elbow flexion and hand grip bilaterally) for each patient. Drug efficacy was examined by comparing the percent change in strength for patients on drug vs. placebo. Secondary efficacy variables included: forced vital capacity (FVC), SMA functional rating scale (SMAFRS), and mini-Sickness Impact Profile (SIP). RESULTS: Eighty-four patients, with type II or III SMA, were enrolled at eight sites across the United States. There were no differences in baseline features. There was no difference between the placebo and drug groups in any outcome measure. CONCLUSIONS: This study demonstrates the feasibility of this trial design and provides data for the design of future clinical trials in SMA.

Acetates↗
PubMed2001

Phase III randomized trial of gabapentin in patients with amyotrophic lateral sclerosis.

BACKGROUND: Preclinical and clinical studies of gabapentin in patients with ALS led the authors to undertake a phase III randomized clinical trial. METHODS: Patients were randomly assigned, in a double-blinded fashion, to receive oral gabapentin 3,600 mg or placebo daily for 9 months. The primary outcome measure was the average rate of decline in isometric arm muscle strength for those with two or more evaluations. RESULTS: Two hundred four patients enrolled, 196 had two or more evaluations, and 128 patients completed the study. The mean rate of decline of the arm muscle strength was not significantly different between the groups. Moreover, there was no beneficial effect upon the rate of decline of other secondary measures (vital capacity, survival, ALS functional rating scale, timed walking) nor was there any symptomatic benefit. In fact, analysis of the combined data from the phase II and III trials revealed a significantly more rapid decline of forced vital capacity in patients treated with gabapentin. CONCLUSION: These data provide no evidence of a beneficial effect of gabapentin on disease progression or symptoms in patients with ALS.

Acetates↗
PubMed2001

Trypanosoma evansi: a convenient model for studying intracellular Ca(2+) homeostasis using fluorometric ratio imaging from single parasites.

The aim of this work was to measure, for the first time, the basal cytosolic Ca(2+) levels of Trypanosoma evansi and to explore the possibility of observing changes in the intracellular Ca(2+) concentration ([Ca(2+)](i)) using fluorescence ratio imaging techniques in single isolated parasites of this species. Under appropriate loading conditions, the high intracellular levels of the Ca(2+) fluorescence probe Fura-2 permits resolution, in real time, of single parasite [Ca(2+)](i) signals. Measurements of the basal [Ca(2+)](i) indicate that homeostatic mechanisms maintain [Ca(2+)](i) at 106 +/- 38 (n = 32) nM in the presence of 2 mM extracellular calcium. The resting [Ca(2+)](i) was unaffected by changes in extracellular Ca(2+) in the range from 0 to 10 mM. The Ca(2+) ionophore A23187 induced a large increase in [Ca(2+)](i) which (i) reached a steady state value even in the simultaneous presence of both external calcium and ionophore and (ii) returned to base line upon removal of extracellular Ca(2+). A dose-response curve of the protonophore nigericin shows that T. evansi contains an important pH-sensitive intracellular pool which may be released by this drug with a K(1/2) of 8 microM. These data demonstrate that this parasite contains highly efficient systems to control [Ca(2+)](i). Finally, our results, with the use of sera as source of an antibody-complement to induce Ca(2+) entry, demonstrate that it is possible to resolve fast [Ca(2+)](i) signals in single parasites from T. evansi.

Animals↗
PubMed2001

Performance characteristics of the COBAS AmpliScreen HIV-1 test, version 1.5, an assay designed for screening plasma mini-pools.

BACKGROUND: The COBAS AmpliScreen HIV-1 test, version 1.5 (v1.5) (Roche Molecular Systems), is designed for screening pools composed of samples from 24 individual units of blood or plasma. A specimen-processing procedure (Multiprep) simultaneously concentrates and extracts HIV-1, HCV, and HBV particles from plasma and incorporates an HIV-1 internal control (IC) RNA. Processed samples are amplified by RT-PCR using HIV-1-specific primers and detected by hybridization of the amplified products to HIV-1- and IC-specific oligonucleotide probes. STUDY DESIGN AND METHODS: Plasma samples containing known quantities of HIV-1 were used to evaluate analytical sensitivity and precision and to validate a pool testing algorithm. Analytical specificity was evaluated by adding various viruses and bacteria to HIV-1-negative plasma. Seroconversion panels were tested to estimate the window-period reduction achieved by RNA testing. RESULTS: The analytical sensitivity of the test (concentration that yields > or = 95% positive results in a set of replicate tests) was 25 copies of HIV-1 RNA per mL of pooled plasma. Representative strains from all HIV-1 group M subtypes were reproducibly detected (> 95% positive results) at concentrations of 20 to 200 viral particles per mL. The test did not cross-react with a set of 31 viral and 5 bacterial isolates, and it yielded negative results on a panel of 500 blood samples from HIV-1-seronegative donors. Plasma samples containing abnormally high levels of Hb, albumin, triglycerides, or bilirubin did not interfere with the test. HIV-1 RNA was detected 2 to 14 days before HIV-1 antibody and 0 to 28 days before p24 antigen. The test specifically detected pools containing a single positive unit with 2400 HIV-1 RNA copies per mL and correctly identified the positive unit. CONCLUSION: The COBAS AmpliScreen HIV-1 test, v1.5, has sufficient sensitivity to detect a single infected unit containing 600 copies of HIV-1 per mL in a pool with 23 uninfected units and should reduce the window period between infection and seroconversion by at least 2 to 14 days.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Regulation of serine-type exoproteinases by endogenous inhibitors present in exoantigens of the mycelial form of Paracoccidioides brasiliensis.

We have partially characterized some biochemical properties of exoproteinases secreted into culture medium by the mycelial form of Paracoccidioides brasiliensis, a dimorphic fungus that causes human disease in Latin America. Proteinase activity was analyzed in solid- and liquid-phase systems using zymography and Azocoll, respectively. Minimal or no gelatinase activity was observed by zymography in the crude filtrates among proteins with a relative mobility greater than 200 kDa. When the crude filtrate was fractionated by isoelectric focusing or ion exchange chromatography, we observed striking activation of gelatinases, both those of high apparent molecular mass and alkaline isoelectric points (pI), as well as those of lower molecular mass and acidic pI. The apparent high molecular mass gelatinases, pI 10, showed optimal activity at pH 7.0. They were totally inhibited by phenylmethylsulfonylfluoride and partially inhibited by incubation with previously neutralized fractions of pI 5.4 and 6.1. The latter inhibition could be reversed by exposure to 10% isopropanol. These results provide evidence of regulatory mechanisms controlling proteinase activity in secreted proteins. The principal mechanism appears to be the formation of reversible complexes with endogenous inhibitors.

Antigens, Fungal↗
PubMed2001

Management of an outbreak of vancomycin-resistant enterococci in the medical intensive care unit of a cancer center.

Between November 1996 and February 1997, 17 episodes of vancomycin-resistant enterococci (VRE) infection or colonization (9 infections, 8 colonizations), all with the same or a similar genomic DNA pattern, were identified in the medical intensive care unit (MICU) of a tertiary-care cancer hospital. The cases were genotypically traced to a patient who was admitted to the hospital in September 1996 and who, by December 1996, had four different admissions to the MICU. Multifaceted infection control measures, including decontamination of the environment and of nondisposable equipment, halted the nosocomial transmission of VRE in the MICU.

Cancer Care Facilities↗
PubMed2001

Surgical treatment of submucous cleft palate: a comparative trial of two modalities for palatal closure.

Submucous cleft palate is a congenital malformation with specific clinical and anatomical features. It can be present with or without velopharyngeal insufficiency. Surgical treatment of this malformation is indicated only when velopharyngeal insufficiency has been demonstrated. This article compares two modalities of surgical treatment for submucous cleft palate. The first includes a minimal incision palatopharyngoplasty, as described in a previous report. The second combines the first technique with additional individualized velopharyngeal surgery (individualized pharyngeal flap or sphincter pharyngoplasty) performed simultaneously. The individualized part of the procedure was selected and performed according to the findings of videonasopharyngoscopy and multiview videofluoroscopy, as reported previously. Two hundred and three patients with submucous cleft palate were studied from 1990 to 1999. Videonasopharyngoscopy and multiview videofluoroscopy demonstrated velopharyngeal insufficiency in 72 patients, who were randomly divided into two groups. Those in group 1 (n = 37) underwent a minimal incision palatopharyngoplasty. Patients in group 2 (n = 35) also underwent that procedure but simultaneously received individualized pharyngeal flap or sphincter pharyngoplasty, according to the findings of videonasopharyngoscopy and multiview videofluoroscopy. The median age of the patients from both groups was not significantly different (p > 0.5). The frequency of residual velopharyngeal insufficiency after palatal closure was not significantly different in both groups of patients (14 percent versus 11 percent; p > 0.5). The mean size of the gap at the velopharyngeal sphincter during speech was not significantly different in both groups of patients before surgery (23 percent versus 22 percent; p > 0.5). After the surgical procedures, there was a nonsignificant difference between both groups of patients in mean residual size of the gap in cases of velopharyngeal insufficiency (7 percent versus 8 percent; p > 0.5). It seems that minimal incision palatopharyngoplasty is a safe and reliable procedure for palatal closure in patients with submucous cleft palate. The use of additional individualized velopharyngeal surgery performed simultaneously did not seem to decrease the frequency of residual velopharyngeal insufficiency. Moreover, the residual size of the gap at the velopharyngeal sphincter was not significantly reduced when an additional surgical procedure was performed simultaneously with palatal closure.

Articulation Disorders↗
PubMed2000

Incenp and an aurora-like kinase form a complex essential for chromosome segregation and efficient completion of cytokinesis.

BACKGROUND: In animal cells, cytokinesis begins shortly after the sister chromatids move to the spindle poles. The inner centromere protein (Incenp)has been implicated in both chromosome segregation and cytokinesis, but it is not known exactly how it mediates these two distinct processes. RESULTS: We identified two Caenorhabditis elegans proteins, ICP-1 and ICP-2, with significant homology in their carboxyl termini to the corresponding region of vertebrate Incenp. Embryos depleted of ICP-1 by RNA-mediated interference had defects in both chromosome segregation and cytokinesis. Depletion of the Aurora-like kinase AIR-2 resulted in a similar phenotype. The carboxy-terminal region of Incenp is also homologous to that in Sli15p, a budding yeast protein that functions with the yeast Aurora kinase Ipl1p. ICP-1 bound C. elegans AIR-2 in vitro, and the corresponding mammalian orthologs Incenp and AIRK2 could be co-immunoprecipitated from cell extracts. A significant fraction of embryos depleted of ICP-1 and AIR-2 completed one cell division over the course of several cell cycles. ICP-1 promoted the stable localization of ZEN-4 (also known as CeMKLP1), a kinesin-like protein required for central spindle assembly. CONCLUSIONS: ICP-1 and AIR-2 are part of a complex that is essential for chromosome segregation and for efficient completion of cytokinesis. We propose that this complex acts by promoting dissolution of sister chromatid cohesion and the assembly of the central spindle.

Amino Acid Sequence↗
PubMed2000

Experience with PCR screening.

The COBAS AmpliScreen Hepatitis C (HCV) Test, Version 2.0, which is designed for screening pools composed of samples from individual units of blood or plasma, employs a MultiPrep sample processing procedure that simultaneously extracts and concentrates HCV, HIV-1 and Hepatitis B virus particles from plasma. An HCV Internal Control (IC) RNA serves as an extraction and amplification control for each independently processed sample. Processed samples are amplified by RT-PCR using HCV-specific complementary primers and detected by hybridization of the amplified products to HCV- and IC-specific oligonucleotide probes. The analytical sensitivity of the test is 25 International Units (IU) of HCV per mL of pooled plasma; all HCV genotypes are detected with similar efficiency. The test detected HCV RNA 23 to 32 days prior to anti-HCV antibody seroconversion for four of the five seroconversion panels tested. The test had sufficient sensitivity to reproducibly detect a single infected unit containing 2.4 x 10(3) copies of HCV per mL in a pool with 23 uninfected units. COBAS AmpliScreen tests for HIV-1 and HBV now being validated by Roche Molecular Systems also incorporate the MultiPrep specimen processing method, thereby making it possible to use a single processed specimen to screen for all three viruses.

Genotype↗
PubMed1999

A novel peptide-SH3 interaction.

SH3 domains constitute a family of protein-protein interaction modules that bind to peptides displaying an X-proline-X-X-proline (XPXXP) consensus. We report that the SH3 domain of Eps8, a substrate of receptor and non-receptor tyrosine kinases, displays a novel and unique binding preference. By a combination of approaches including (i) screening of phage-displayed random peptide libraries, (ii) mapping of the binding regions on three physiological interactors of Eps8, (iii) alanine scanning of binding peptides and (iv) in vitro cross-linking, we demonstrate that a proline-X-X-aspartate-tyrosine (PXXDY) consensus is indispensable for binding to the SH3 domain of Eps8. Screening of the Expressed Sequence Tags database allowed the identification of three Eps8-related genes, whose SH3s also display unusual binding preferences and constitute a phylogenetically distinct subfamily within the SH3 family. Thus, Eps8 identifies a novel family of SH3-containing proteins that do not bind to canonical XPXXP-containing peptides, and that establish distinct interactions in the signaling network.

Adaptor Proteins, Signal Transducing↗