Search PubMed⌕ Search

Biomedical subjects

L Porto

Publications and source records attributed to L Porto.

6 recordsLinked to original sources
PubMed1998

Antigenic diversity of hepatitis B virus strains of genotype F in Amerindians and other population groups from Venezuela.

The adw4 subtype of hepatitis B virus (HBV) belongs to a unique genomic group (genotype F) representing the original HBV strains from the New World. Data regarding the prevalence of this subtype among HBV carriers in South America are, however, scarce, and those concerning HBV genotype F are based on only a few samples from Latin America. In this study, serum samples were obtained from 141 hepatitis B surface antigen (HBsAg) carriers from Amerindians and urban populations from Venezuela. The HBsAg subtype was identified with monoclonal antibodies in 105 samples, and the HBV genotype was identified by reverse-phase hybridization with DNA fragments in 58 samples. The adw4 subtype was highly prevalent in the population studied (75%); among the Amerindians, the prevalence was 97%. The adw2 subtype was also present (10%), while other subtypes (ayw3 and ayw4) were only occasionally found. The HBV subtype was associated with the expected genotype in most cases (80%), and thus genotype F was highly prevalent. Sequencing of viral strains that gave genotypes unpredicted by the HBsAg subtyping confirmed seven of them as belonging to not previously described genotype-subtype associations: namely, adw2 and ayw4 within genotype F.

Amino Acid Substitution↗
PubMed1994

Epidemiology of hepatitis C virus in western Venezuela: lack of specific antibody in Indian communities.

Hepatitis C virus (HCV) is transmitted mainly by the parenteral route after percutaneous exposure to virus-infected products or body fluids. Thus, HCV shares with hepatitis B and D (HBV, HDV) viruses this common transmission route. The prevalence of antibody against HCV (anti-HCV) was studied in 1155 serum samples from individuals at risk of infection by bloodborne or sexually transmitted agents, as well as from others lacking such risk factors, from the city of Maracaibo, Venezuela. Anti-HCV and serological markers of infection by HBV and HDV were also studied in further 550 samples taken from Bari Indians living in different communities in the Perijá mountains, State of Zulia, Venezuela. The results obtained showed that recipients of blood or blood products are at increased risk of HCV infection in Maracaibo, whereas sexual transmission plays only a minor role if any. Both HBV and HDV infections were highly prevalent among Bari Indians (64.4% positive for anti-HBc; 11.1% of HBsAg carriers; 15.3% positive for anti-HDV among HBsAg carriers). No anti-HCV positive samples were, however, detected among them, thus suggesting either that HCV has not still reached this population or that HBV and HDV are transmitted by routes unshared by HCV. Anti-HCV was also absent among samples from mentally retarded patients from Maracaibo, thus confirming similar findings from other countries and supporting the existence of specific transmission mechanisms for HBV and HDV which are not working for HCV.

Antibody Specificity↗
PubMed1987

Survey of clinical experience with nimodipine in patients with subarachnoid hemorrhage.

The present studies show that nimodipine prevents and/or improves permanent ischemic neurological deficits in patients with subarachnoid hemorrhage. This was particularly marked in four double-blind, placebo-controlled studies in which statistically significant reductions in mortality and morbidity as consequence of cerebral vasospasm were found. The drug has been shown to increase cerebral blood flow, to reduce vasoconstriction, although not to fully prevent angiographic vasospasm, and to improve central conduction time. Nimodipine did not increase the rate of rebleeding. Its administration during anesthesia does not result in management problems. In general, nimodipine was well tolerated. Side effects were recorded mainly in open studies using the intravenous formulation and consisted mainly of decreases in blood pressure and headaches. Transient increases in liver enzymes may be due to the organic solvent. Hence, all results indicate that patients with subarachnoid hemorrhage will benefit from preventive or therapeutic nimodipine treatment.

Brain Ischemia↗
PubMed1976

Recognizing spontaneous spinal epidural hematoma.

Sudden, often severe pain in the spinal region that is followed-sometimes within minutes-by paraplegia may signal spontaneous spinal epidural hematoma. This is a true surgical emergency calling for immediate laminectomy. Otherwise, the neurologic deficit becomes irreversible and the patient probably will die. The cause may be a fall or straining but in most cases there's no history of trauma. A myelogram reveals a block at the level of the hematoma, usually in the thoracic region or in the cervicothoracic or thoracolumbar area. Manometric tests shouldn't be done because they can increase the neurologic deficit. Urinary retention and sensitivity to pinprick at the level of the hematoma are additional diagnostic clues. The case reported here and 13 others from the literature point up the importance of prompt surgical treatment. Eight of the 12 patients who had laminectomy improved and five of them recovered completly, but both of the patients who were not treated surgically died.

Aged↗