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M Marín

Publications and source records attributed to M Marín.

53 records · Page 3Linked to original sources
PubMed1981

[Analysis of the stability and local cooperativity of DNA: proposal of a molecular mechanism for the initiation of the transcription of gene A3 of bacteriophage T7 by the RNA polymerase from E. coli].

RNA polymerase (RNAP) complexed to the A3 promoter of bacteriophage T7 is known to unwind a DNA segment located downstream of the Pribnow box. This finding can be accounted for if it is assumed that the subunit sigma of RNAP unstabilizes three GC base pairs located just upstream of the transcription start. As a consequence, the rate of promoter utilisation might be related to the relative stability of the DNA between the "Pribnow box" and the transcription start.

Base Composition↗
PubMedDate not supplied

[A comparison of lymphocyte populations of the blood and bronchoalveolar lavage in AIDS patients].

Changes in cell immunity made manifest by decreases in blood levels of CD4 T cells is the main indicator of progressing HIV infection. The decrease in these lymphocytes, as well as in the CD4/CD8 index and increases in suppressant or cytotoxic CD8 cells can be detected in bronchoalveolar (BAL) lung samples. It is not clear whether the high incidence of respiratory system diseases in HIV patients stems from local or systemic immune changes. The aim of this study was to compare changes in the systemic cell immunity studied in samples of peripheral blood with changes detected in BAL samples from HIV patients with acute respiratory disease. We studied 42 patients in the advanced stages of AIDS (C3 by Centers for Disease Control classification) who were hospitalized for acute respiratory disease and who underwent diagnostic fiberoptic bronchoscopy and BAL. Cell counts and lymphocyte populations were analyzed by flow cytometry in samples of peripheral blood and BAL. The percentage of CD4 lymphocytes and the CD4/CD8 index were lower in BAL, particularly in patients with blood CD4 levels below 12% of the total T cell population, or at a level of 20 CD4 cells/microliters. Changes in cell immunity in patients with advanced HIV infection (C3 classification) and acute respiratory disease are more manifest locally in the lung than peripherally in blood. Lung depletion of CD4 T cells in the lung can be predicted based on blood levels.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Evaluation of the upgraded amplified Mycobacterium tuberculosis direct test (gen-probe) for direct detection of Mycobacterium tuberculosis in respiratory and non-respiratory specimens.

We evaluated the upgraded Amplified Mycobacterium Tuberculosis Direct Test kit (AMTD) (Gen-Probe Inc.) for the direct detection of Mycobacterium tuberculosis in respiratory and non-respiratory specimens, and compared the results between the traditional 30,000 RLUs cutoff criteria (C) and three equivocal ranges (30,000-100,000, R1; 30,000-500,000, R2; and 30,000-1,000,000, R3). We tested 663 respiratory and 238 non-respiratory samples from 464 patients. The gold standard was considered to be the combination of culture and clinical data. One hundred and nineteen samples were from 56 patients with pulmonary tuberculosis, and 36 samples were from 19 patients with extrapulmonary tuberculosis. When C criteria was applied, the sensitivity and specificity values were 90.8 and 93.0% for respiratory specimens, while they were 88.9 and 92.1% for non-respiratory specimens (p = NS). The sensitivity was significantly higher in smear-positive specimens (96.7%) than in smear-negative ones (81.0%) (p < 0.05). When compared with C criteria, the overall sensitivity was maintained at 90.3% for R1 criteria, and slightly decreased to 89.7% for R2 and R3 criteria (p = NS). Overall, specificity increased significantly from 92.9% (C) to 97.5% (R1), 99.1% (R2), and 99.2% (R3). Application of R2 or R3 criteria improved significantly the specificity of the test with little decrease in sensitivity.

Humans↗
PubMedDate not supplied

[Non-fermenting Gram-negative bacilli: distribution in clinical specimens and antimicrobial susceptibility].

In the present work was studied the prevalence, distribution in clinical specimens, and antimicrobial susceptibility of non-fermentative Gram-negative bacilli (NFGNB) from patients attended at Hospital "Angela I. de Llano" (Corrientes, Argentina). A total of 125 strains of NFGNB were recovered from various clinical specimens from July, 1997 to December, 1998. Isolates were identified by classical biochemical tests. Drug sensitivity was performed by standard methods with cefotaxime (CTX), ceftazidime (CAZ), piperacillin (PIP), ampicillin-sulbactam (AMS), piperacillin/tazobactam (TAZ), imipenem (IMP), amikacin (AKN), gentamicin (GEN) and ciprofloxacin (CIP). The most common isolates were Pseudomonas aeruginosa (48.8%); Acinetobacter baumannii (16.8%), Acinetobacter spp. (6.4%), Chryseobacterium spp. (5.6%), Stenotrophomonas maltophilia (4%), and others (18.4%). Most of them were recovered from respiratory secretions (36.0%), and urine (26.4%). IMP was the most effective antimicrobial. Many species of NFGNB showed resistance to several antibiotics tested (CTX, GEN, AMS, and CIP). Due to multiresistance found by more prevalent NFGNB, constant survey of antibacterial sensibility are essential for a correct control and management of nosocomial infections, and ambulatory patients with some risk factors.

Argentina↗
PubMedDate not supplied

[Consensus on antimicrobial sensitivity tests in gram-positive cocci. Subcommittee on Antimicrobials, SADEBAC (Argentinian Society of Clinical Bacteriology), Argentinian Association of Microbiology].

Antimicrobial susceptibility testing is mainly performed in Argentina by disk diffusion method, following National Committee for Clinical Laboratory Standards (NCCLS) recommendations. We worked out new recommendations for the reporting and interpretation of this test when dealing with gram-positive cocci, in accordance to local trends and epidemiology. General considerations for performing the diffusion assay, quality control, and an update on susceptibility testing for gram-positive cocci are reported in this first document. The present update should be considered as a group of recommendations summarized by Argentinean experts and as the result of a consensus meeting coordinated by the Subcomisión de Antimicrobianos of the Sociedad Argentina de Bacteriología Clínica (Asociación Argentina de Microbiología). Experts in antimicrobial agents were convened in order to prepare this final document. These recommendations take into account local needs, affordability and availability to be used in current practice, tending to contribute to the correct antimicrobial treatment election, according to the particular microorganism and the infection sites.

Algorithms↗
PubMedDate not supplied

[Consensus for antimicrobial susceptibility testing for Enterobacteriaceae. Subcommittee on Antimicrobials, SADEBAC (Argentinian Society of Clinical Bacteriology), Argentinian Association of Microbiology].

Taking into account previous recommendations from the National Committee for Clinical Laboratory Standards (NCCLS), the Antimicrobial Committee, Sociedad Argentina de Bacteriología Clínica (SADEBAC), Asociación Argentina de Microbiología (AAM), and the experience from its members and some invited microbiologists, a consensus was obtained for antimicrobial susceptibility testing and interpretation in most frequent enterobacterial species isolated from clinical samples in our region. This document describes the natural antimicrobial resistance of some Enterobacteriaceae family members, including the resistance profiles due to their own chromosomal encoded beta-lactamases. A list of the antimicrobial agents that should be tested, their position on the agar plates, in order to detect the most frequent antimicrobial resistance mechanisms, and considerations on which antimicrobial agents should be reported regarding to the infection site and patient characteristics are included. Also, a description on appropriate phenotypic screening and confirmatory test for detection of prevalent extended spectrum beta-lactamases in our region are presented. Finally, a summary on frequent antimicrobial susceptibility profiles and their probably associated resistance mechanisms, and some infrequent antimicrobial resistance profiles that deserve confirmation are outlined.

Anti-Bacterial Agents↗
PubMedDate not supplied

Molecular staging of bladder cancer with RT-PCR assay for CK20 in peripheral blood, bone marrow and lymph nodes: comparison with standard histological staging.

BACKGROUND: The aim of this study was to analyze whether the CK20 reverse transcriptase polymerase chain reaction (RT-PCR) is suitable for detecting circulating tumor cells and residual tumor cells in lymph nodes, in patients with muscle invasive transitional cell carcinoma (TCC) of the bladder, and to compare these results with standard histological staging. PATIENTS AND METHODS: The nested RT-PCR assay was used to analyze the CK20 transcript in the peripheral blood, bone marrow, lymph nodes, the tumor and normal biopsies of bladder from 57 patients with invasive TCC of the bladder, who underwent radical cystectomy, and from 9 patients with noninvasive TCC. RESULTS: Lymph node pathological status was positive in 24 out of the 57 patients studied and all of them except I showed expression of CK20, with a correlation between histological technique and RT-PCR of 95.8%. A statistically significant correlation of lymph node CK20 RT-PCR with the standard risk factor of pathological stage (p = 0.04) was observed Blood and bone marrow CK20 RT-PCR showed no correlation with pathological stage. CONCLUSION: Lymph node CK 20 RT-PCR correlates with pathological stage in bladder cancer. The CK20 RT-PCR assay appears to be a highly sensitive and specific method for detecting circulating tumor cells and residual disease in lymph nodes in patients with invasive bladder cancer. Further evaluation of the significance of CK20 as a molecular marker for staging and follow-up in these patients is necessary.

Adult↗