Search PubMed⌕ Search

Biomedical subjects

E Rojas

Publications and source records attributed to E Rojas.

At least 271 records · Page 15Linked to original sources
PubMedDate not supplied

Relationship between the degree of poverty and the IgE response to Ascaris infection in slum children.

We examined a group of urban slum children in Caracas, Venezuela, and demonstrated the relationship that exists between poverty, conditions of hygiene and the prevalence of helminth infection. Concordant with the high prevalence of helminth infection in these children, the total serum levels of immunoglobulin E (IgE) and blood eosinophilia were elevated and were directly related to the degree of poverty and lack of sanitary facilities. However, in contrast, the reverse pattern was observed for the specific allergic response to these parasites. Thus, the immediate hypersensitivity skin test reactivity to Ascaris antigens, and the serum levels of specific anti-Ascaris IgE antibody, were lowest in the poorest children, who had the highest prevalence of helminth infection and the highest total IgE levels. As allergic-type reactions may participate in protective mechanisms against helminths, these results suggest that poverty and poor sanitary conditions may, by influencing the IgE response, compromise the resistance of such children to parasitic infections.

Animals↗
PubMedDate not supplied

The venom of Bothrops asper from Guatemala: toxic activities and neutralization by antivenoms.

Bothrops asper is responsible for approximately half of the snakebite envenomations in Central America. Despite its medical relevance, only the venom of Costa Rican populations of this species has been studied to some detail, and there is very little information on intraspecies variability in venom composition and toxicity. Venom of B. asper from Guatemala was analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and two-dimensional gel electrophoresis, and its basic pharmacological activities were investigated with standard laboratory assays. Venom has lethal, hemorrhagic, myotoxic, edema-forming, coagulant, defibrinating and phospholipase A(2) activities, showing a similar toxicological profile to the one previously described for B. asper from Costa Rica. In addition, polyvalent antivenoms produced in Mexico and Costa Rica, and currently used in Guatemala, were tested for their ability to neutralize venom's toxic activities. Both antivenoms were effective against all effects studied, although the Costa Rican product showed higher potency against most activities tested and higher antibody titer against venom components, as determined by enzyme immunoassay. It is suggested that different dosage regimes should be considered when using these antivenoms in B. asper envenomations in Guatemala.

Animals↗
PubMedDate not supplied

[Xenodiagnosis using Lutzomyia youngi in Venezuelan cases of cutaneous leishmaniasis due to Leishmania braziliensis].

Eight patients infected with Leishmania braziliensis were used for xenodiagnosis with Lutzomyia youngi, before and after specific antileishmanial treatment with "glucantime" and "gabbromycin". All of them infected sandflies fed on the borders of the skin lesions before the treatment, suggesting that infected persons might act as reservoirs of infection for an indoor-biting sandfly species. The negative results obtained by xenodiagnosis carried out after specific treatment of the same individuals indicated cure of the patients, and a reduction of risk for further intradomiciliary transmission.

Adolescent↗
PubMedDate not supplied

Multiple potassium and chloride channels in the human colon carcinoma cell line SW1116.

SW1116 cells have a profound capacity for secreting mucin molecules bearing the Lewisa epitope. Mucin molecules with the same epitope have been found to be elevated in the serum of patients with cystic fibrosis, a disease with defective ion channels. We therefore decided to study ion channels in this cell line. In the present work, we report the presence of two K(+)-channels and two Cl(-)-channels in the apical membrane of SW1116 cells. One of the K(+)-channels has a large conductance (approximately 278 pS), anomalous rectifying properties, and is inactivated rapidly. The second type exhibited a linear I/V curve (19 pS), was voltage insensitive and inactivation was not observed. In cell-attached patches, spontaneous openings of chloride channels were seen with higher frequency than previously reported in other colon carcinoma cell lines or airway epithelial cells. Inside-out experiments allowed identification of two different Cl(-)-channels (Cl(-)-1 and Cl(-)-2). Both exhibited rectification, but in opposite directions, and both were insensitive to NIPAB.

Chloride Channels↗
PubMedDate not supplied

Properties of the ryanodine receptor present in the sarcoplasmic reticulum from lobster skeletal muscle.

Microsomal sarcoplasmic reticulum (SR) fractions from lobster skeletal muscle were found to bind [3H]-ryanodine. [3H]-ryanodine binding was enhanced by AMP, Ca2+ and caffeine, and significantly diminished by ATP, Ba2+ and Sr2+. Furthermore, dantrolene and ruthenium red, two classical inhibitors of Ca2+ release from the SR, blocked [3H]-ryanodine binding. Similarly, tetracaine, known to block the charge movement associated with excitation-contraction coupling in vertebrate muscle, inhibited the binding of the alkaloid. Our lobster SR preparation exhibited a single high-affinity ryanodine binding site (Kd = 6.6 nM, Bmax = 10 pmol/mg protein). Since SDS-PAGE of the SR proteins revealed a major band c. 565 kDa which comigrated with the putative ryanodine receptor from both rat and chicken skeletal muscle, we concluded that lobster skeletal muscle is equipped with the 565 kDa ryanodine receptor. Finally, incorporation of the SR microsomal fraction from lobster into planar bilayer membranes revealed the presence of a ryanodine-sensitive Ca2+ channel activity (160 pS in symmetrical 200 mM CsCl solutions). We concluded that both the crustacean and vertebrate skeletal muscle ryanodine receptor share the relevant properties such as molecular weight and affinity for ryanodine and inositol 1,4,5 triphosphate. However, there are important differences between the two receptors including differential effects of the alkaloid on the Ca2+ release channel and modulation of the receptor by nucleotides.

Animals↗
PubMedDate not supplied

[Tumors of the posterior fossa in children].

INTRODUCTION: Primary tumours of the CNS form 20% of the neoplasias seen in children. They are the second commonest type of cancer seen in childhood, after leukemia. A significant proportion of paediatric cerebral tumours (> 50%) are intratentorial. OBJECTIVE: To find the frequency and clinicopathological behavior of posterior fossa tumours in children seen at our hospital. PATIENTS AND METHODS: From the hospital records, a descriptive, retrospective study was made of 112 children with tumours of the posterior fossa who were attended at the Institute of Neurology and Neurosurgery between January 1980 and December 1997. The variables: age, sex, clinical findings, site and extent of the tumour and its histological description were recorded. The mean, standard deviation, frequency distribution and chi-squared test were used, depending on the type of variable to be analyzed. RESULTS: The age of the patients when the diagnosis was made was between 8 months and 15 years (mean = 8.32 years). The male/female ratio was 59/53 (1.1/1). The commonest site of the tumours was the cerebellum (58.9%). The predominant histological types were medulloblastoma (33.92%) and astrocytoma (19.64%) in the cerebellum, glioma in the brain stem (10.71%) and ependymoma in the i.v. ventricle (8.09%). CONCLUSIONS: Endocranial hypertension and the cerebellar syndrome were the predominant clinical findings in medulloblastoma, cerebellar astrocytoma and ependymoma. In brainstem gliomas there was often involvement of several cranial nerves and long tracts.

Adolescent↗
PubMedDate not supplied

[Phobic epilepsy].

Explore the source record for details and available documents.

Diagnosis, Differential↗