PubMed Health⌕ Search

Biomedical subjects

Fernando Chaves

Publications and source records attributed to Fernando Chaves.

23 records · Page 2Linked to original sources
PubMed2003

Intramuscular administration of antivenoms in experimental envenomation by Bothrops asper: comparison between Fab and IgG.

The efficacy of intramuscular (im) administration of sheep Fab and IgG antivenoms was assessed in a mouse experimental model of envenomation by Bothrops asper, in order to test if the more rapid absorption of Fab improves neutralization. Both antivenoms were adjusted to have a similar neutralizing potency in assays involving preincubation of venom and antivenom. Neither antivenom was effective in neutralizing lethality, nor in prolonging the time of death, in mice injected with either 3, 2 or 1.5 LD(50)s of venom by the intraperitoneal (ip) route, in experiments in which antivenoms were administered im immediately after envenomation. Antivenoms were effective in the neutralization of defibrinating activity, even if treatment was performed 30 min after envenomation, with no differences between IgG and Fab. Regarding neutralization of local effects, i.e. myonecrosis and hemorrhage, im administration of antivenoms at a site distant from the venom-injection site was completely ineffective in reducing the extent of local tissue damage. However, partial neutralization of these effects was achieved if antivenoms were administered im at the same site of venom injection, provided treatment was performed immediately after envenomation. Fab antivenom was slightly more effective than IgG antivenom in the neutralization of myotoxicity under these conditions, although a similar efficacy was observed between these antivenoms regarding neutralization of hemorrhagic effect. Our observations do not evidence major differences in the neutralizing ability of Fab and IgG antivenoms when applied by the im route, and do not support the hypothesis that im administration of Fab antivenoms constitutes an effective alternative to treat B. asper envenomations.

Animals↗
PubMed2002

Value of autopsy in nonimmune hydrops fetalis: series of 51 stillborn fetuses.

Nonimmune hydrops fetalis (NIHF) is used to describe fetuses and newborns with generalized edema and cavity effusions. It is helpful to alert physicians about the presence of anemia, heart failure, and/or hypoproteinemia, but this diagnosis is frequently overlooked. We reviewed the autopsy files from 1990 to 2000, selected all cases with NIHF including clinical information (with maternal laboratory tests and ultrasound), and classified patients by etiology. Among 840 stillborn autopsies during the 11-year period, we found 51 with NIHF (6.07%). The clinical summary had mentioned hydrops in 14 patients and the etiology in another 7 by fetal ultrasonography, but without addressing the possibility of hydrops. In the remaining 30 cases neither hydrops nor an etiology was mentioned. Other pertinent diagnoses were maternal diabetes mellitus (4), congenital heart disease (3), and cystic hygroma (2). The following diagnoses were made in one instance each: cardiac tumor, twin transfusion syndrome, congenital adenomatoid malformation, syphilis, Turner syndrome, and cerebral arteriovenous malformation. Postmortem and placental examination confirmed the following etiologies: congenital infections (17); placental pathology significant enough to explain NIHF (10); cardiovascular diseases (8) (further classified as congenital heart disease [3], rhabdomyoma [1], and vascular malformations [4]); chromosomal abnormalities (6); uncontrolled maternal diabetes (4); intrathoracic lesions (2); prune-belly syndrome (2); and idiopathic NIHF (2). Only 3.9% of the cases studied had no identifiable etiology. The cause of hydrops was confirmed by autopsy in 47 fetuses (92%), which further supports the importance of performing an autopsy. Thirty-two cases (62.74%) had placental abnormalities helpful to the etiology (parvovirus, syphilis, Turner's syndrome, etc.). In 20 instances, the clinical summary had no mention of either hydrops or any of the diseases leading to it. The autopsy in conjunction with placental examination and fetal ultrasound represent the best combination to determine the etiology of NIHF among stillborn fetuses.

Autopsy↗
PubMed2002

[Recent transmission of tuberculosis in an area with low incidence: epidemiological and molecular study].

BACKGROUND: Few reports have analysed the transmission of tuberculosis in rural areas with a low incidence of disease. PATIENTS AND METHOD: A population-based molecular epidemiological study of patients with tuberculosis, diagnosed by culture, was conducted in Segovia (Spain) between 1995 and 1999. Clinical, demographic and epidemiological data were reviewed. Patients whose clinical isolates of Mycobacterium tuberculosis had identical restriction-fragment-length-polymorphism (RFLP) patterns with IS6110 and spoligotyping were included in clusters. RESULTS: Of 96 patients with positive-culture for M. tuberculosis complex, 6 were considered as false-positive results. The mean incidence rate was 12.3 cases/100,000 inhabitants. Median age was 50.3 (SD: 23.1), 14% was HIV-infected, and 92% of them were living in urban areas (p < 0.01). There were no cases of primary resistance to isoniazid. DNA fingerprint was performed in 87 samples. We identified 8 clusters including 24 patients (27.7%). Clusters had between 2 and 6 cases. Patients aged < 35 years (OR = 3.1; CI 95%, 1.0-9.6) and with lung involvement (OR = 6.8; CI 95%, 1.3-46.4) were more represented in the clusters. Classical epidemiological investigation confirmed a recent transmission in 33% of clustered cases. CONCLUSIONS: The use of both classical and molecular epidemiology reveals the existence of recent transmission cases of tuberculosis in an area with a low incidence of the disease.

Adult↗
PubMed2002

New real-time PCR able to detect in a single tube multiple rifampin resistance mutations and high-level isoniazid resistance mutations in Mycobacterium tuberculosis.

The emergence of resistance to antituberculosis drugs is a relevant matter worldwide, but the retrieval of antibiograms for Mycobacterium tuberculosis is severely delayed when phenotypic methods are used. Genotypic methods allow earlier detection of resistance, although conventional approaches are cumbersome or lack sensitivity or specificity. We aimed to design a new real-time PCR method to detect rifampin (RIF)- and isoniazid (INH)-resistant M. tuberculosis strains in a single reaction tube. First, we characterized the resistant isolates in our area of Spain by DNA sequencing. Some mutation was found within the rpoB core region in all the RIF-resistant (RIF(r)) strains. Forty-six percent of the INH-resistant (INH(r)) strains showed a mutation in katG codon 315, and most of these were associated with high MICs. Eighteen of the RIF(r), INH(r), and multidrug-resistant strains sequenced were tested by our real-time PCR assay; and full concordance of the results of the PCR with the sequencing data was obtained. In addition, a blind test was performed with a panel of 15 different susceptible and resistant strains from throughout Spain, and our results were also in 100% agreement with the sequencing data. Ours is the first assay based on rapid-cycle PCR able to simultaneously detect in a single reaction tube a large variety of mutations associated with RIF resistance (12 different mutations affecting 8 independent codons, including the most prevalent mutations at positions 526 and 531) and the most frequent INH resistance mutations. Our design could be a model for new, rapid genotypic methods able to simultaneously detect a wide variety of antibiotic resistance mutations.

Antitubercular Agents↗