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Biomedical subjects

E Estevez

Publications and source records attributed to E Estevez.

13 recordsLinked to original sources
PubMed2003

Improved LC method to determine ivermectin in plasma.

A simple, rapid and sensitive high-performance liquid chromatographic (HPLC) method has been developed to quantify Ivermectin (IVM) in plasma using an isocratic system with fluorescence detection. The method included a fast liquid phase extraction using cold methanol. HPLC separation was carried out by reversed phase chromatography with a mobile phase composed of methanol:acetonitrile:water with 0.2% acetic acid (45:50:5 v/v/v), pumped at flow rate of 2 ml min(-1). Fluorescence detection was performed at 365 nm (excitation) and 475 nm (emission). The calibration curve for IVM was linear from 0.25 to 100 ng ml(-1). The validation method yielded good results regarding linearity, precision, accuracy, specificity and recoveries. The values of the limit of detection (LOD) and limit of quantification (LOQ) were 0.032 and 0.167 ng ml(-1), respectively.

Chromatography, High Pressure Liquid↗
PubMed2002

Prevalence of erectile dysfunction in Colombia, Ecuador, and Venezuela: a population-based study (DENSA).

The purpose of this study was to estimate the prevalence of erectile dysfunction (ED) in Colombia, Ecuador, and Venezuela. A 49-item questionnaire was completed by 1946 men aged 40 years and older. The age-adjusted combined prevalence of minimal, moderate, and complete ED for all three countries was 53.4%, with 19.8% of all men reporting moderate to complete ED. Age was the variable most strongly linked to ED; the prevalence of complete ED increased markedly in men older than 79 y of age (31.9%) and 70-79 y (17.2%) compared with men aged 40-49 y (<3%). Several medical conditions, such as hypertension, benign prostatic hyperplasia, and diabetes, and the use of medications to treat these conditions were correlated with the prevalence of ED. This study corroborates earlier studies demonstrating that ED is very common, increases dramatically with age, and has multiple correlates, including some that are also risk factors for cardiovascular disease.

Adult↗
PubMed1998

Understanding the mechanism of the zinc-ion stains of biomacromolecules in electrophoresis gels: generalization of the reverse-staining technique.

We have recently shown that a few nanograms of protein separated by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels can be detected by reverse-staining, exploiting the precipitation reaction between zinc(II) and imidazole. Modifications of this method have also been generated to detect gel-isolated nucleic acids and bacterial glycolipids. Because there is no recourse to chemical modifiers, the reverse-staining technique has been valuable when micropreparing these biomacromolecules for later use or characterization. The mechanism underlying the reverse-staining effect, however, remains incompletely understood and this has prevented a further generalization of the technique. Here, we have conducted physicochemical experiments and identified zinc imidazolate (ZnIm2) as the main component of the precipitate that forms along the surface of zinc-imidazole reverse-stained gels. Many staining effects observed when gels containing electrophoretically separated biopolymers are subjected to zinc-imidazole stains have been rationalized. The reverse-staining method has been vastly generalized, now allowing the detection of proteins and glycolipids as well as complexes of these macromolecules in native gels. We demonstrate the application of the reverse-staining technique in situations where Coomassie blue or silver staining was inappropriate or failed to produce detection of the species of interest. The present generalization of the reverse-staining method facilitated the characterization of biomacromolecular interaction partners in mixtures of bacterial glycolipids and human tears.

Bacteria↗
PubMed1996

Effects of prednisolone and dexamethasone in children with alkali burns of the oesophagus.

We compared the efficacies of prednisolone and dexamethasone for treatment of children with oesophageal burns due to ingestion of caustic substances. The criteria of efficacy used were a) stricture severity by 3 weeks post-ingestion, b) reduction in burn severity by 3 weeks post-ingestion and c) number of dilatations required over the first year post-ingestion. Thirty-six children (24 boys and 12 girls; mean age 23.6 +/- 7.4 months) were selected from a total of 63 patients admitted over a ten-year period to the General Hospital of Galicia with second- or third-degree oesophageal burns due to accidental ingestion of liquid alkali preparations. The patients were divided into two groups of 18, one group for treatment with prednisolone (2 mg/kg/day) and the other for treatment with dexamethasone (1 mg/kg/day). Strictures developed in 12 (66.7%) of the children in the prednisolone-treated group and only 7 (38.9%) of the children in the dexamethasone-treated group. Severe strictures developed in 10 (55.6%) of the children in the prednisolone-treated group and only 5 (27.8%) of the children in the dexamethasone treated group. However, there was no significant difference between the groups in the posttreatment distribution of stricture-severity ratings. Burn healing was significantly better in the dexamethasone-treated group. Similarly, the number of dilatations necessary during the first year of treatment was significantly lower in the dexamethasone-treated group. Our results thus indicate that, by comparison with prednisolone, dexamethasone leads to improved burn healing and reduced need for dialatations during the first year post-injury.

Anti-Inflammatory Agents↗
PubMed1996

Motor function of the esophagus after caustic burn.

During the subacute and chronic phases of esophagitis due to ingestion of a caustic substance, the patient commonly displays stricture, esophageal rigidity and dysphagia. We used esophageal manometry, radiology, pH monitoring and 99mTc scintigraphy to investigate esophageal motor function in 25 children (mean age 24 +/- 7 months) with chronic esophagitis after second- and/or third-degree caustic burns. The results were compared with those for a control group of 12 children (mean age 32 +/- 19 months) under surveillance for suspected gastroesophageal reflux (GER) but for whom this pathology was later ruled out. Seventeen (68%) of the lesioned-group children showed esophageal dysfunction as revealed by monitoring of pH over a 24-hour period. Over this period, the mean percentage of time with pH below 4 was 19 +/- 10%, the mean number of reflux episodes was 48 +/- 52, the mean number of reflux episodes lasting longer than 5 min was 10 +/- 5, and the mean duration of the longest reflux episode was 51 +/- 21 min. Manometry indicated that, in the lesioned group, an average of 77 +/- 18% of peristaltic waves were nonpropulsive, while the mean Esophageal Work Index (number of propulsive waves per hour x mean maximum pressure developed during propulsive waves) was 227 +/- 192 units. All of the above means were significantly different (p < 0.01) from the corresponding control-group means. Esophageal strictures were observed in 60% (15) of the children. In 2 cases it was minimal, 2 cases moderate and 11 cases had severe strictures. 99mTc scintigraphy indicated that esophageal transit was slightly delayed in four, moderately delayed in five and severely delayed in 16 of the lesioned-group subjects. There was close correspondence between the results of manometry and scintigraphy as regards severity of esophageal dysfunction. These results indicate that motility disturbances and GER are very frequent sequelae of caustic burns of the esophagus, and should be taken into account when evaluating symptoms and deciding on the therapeutic strategy (including diet) to be followed.

Burns, Chemical↗
PubMed1996

Effects of prednisolone and dexamethasone on alkali burns of the esophagus in rabbit.

Steroids have been widely used to prevent the severe secondary strictures that inevitably follow accidental ingestion of caustic substances by children, though with controversial results. To confirm the efficacy of large early doses of dexamethasone, we conducted an experimental study in rabbits. A cotton swab soaked in sodium hydroxide was placed on the esophageal mucosa of 30 rabbits. The rabbits were then treated with antibiotics and randomly allocated to one of three groups. One group received no steroids; the second group was treated with prednisolone; and the third was given dexamethasone. After 21 days, the rabbits were killed and the severity of the lesion was evaluated by radiological, anatomical, and histological examination. Rabbits with moderate or severe stricture, as defined on the basis of radiological examination, made up 80% of the control group, 70% of the prednisolone-treated group, and 40% of the dexamethasone-treated group. Rabbits with third-degree burns, with or without macroscopic ulcers, made up 60% of the control group, 40% of the prednisolone-treated group, and 30% of the dexamethasone-treated group. On histological examination, rabbits with third-degree lesions made up 70% of the control group, 40% of the prednisolone-treated group, and only 20% of the dexamethasone-treated group. Only the difference between the control and dexamethasone-treated group was statistically significant. Taken together, our results clearly indicate that, in rabbits, rapid postburn administration of dexamethasone leads to significant reductions in the frequency and severity of strictures and in the severity of burns.

Animals↗
PubMed1995

Gallbladder carcinoma in an achondroplastic boy.

Carcinoma of the gallbladder in an extremely rare tumor in childhood. We have found only five cases in the literature. Most of them were associated with an ethnic group - The Navajo Indians - who are known to have high incidence of gallbladder disease. We report here on the exceptional presence of this type of tumor in a child, who also had achondroplasia. This, as far as we can determine, is the first such case ever reported.

Achondroplasia↗
PubMed1987

Iron status in Ecuadorian pregnant women living at 2,800 m altitude: relationship with infant iron status.

An evaluation of iron status was performed in 84 pregnant women at delivery (and in cord blood from their newborn) and in a control group of 32 menstruating women living in Quito (2800 m altitude). Anemia as defined according to the WHO references adjusted to altitude was observed in 46% of pregnant women. Iron deficiency was defined as the combination of a low serum ferritin level (12 micrograms/l or less) and a low transferrin saturation percentage (less than 16%). A moderate elevation in the serum ferritin concentration (between 13 and 50 micrograms/l) associated with low transferrin saturation indicated iron deficiency in an inflammatory context. Iron deficiency was present in 46% of pregnant women. Anemia was associated with iron deficiency in 59% of cases. A correlation between maternal and cord blood hemoglobin was found and some iron parameters in cord blood were related to maternal iron status, and especially to maternal iron stores assessed by serum ferritin concentration.

Altitude↗
PubMedDate not supplied

[High altitude anemia: validity of definition criteria].

The effect of iron and folate supplementation on the hemoglobin response and iron status was studied in male and female equatorian medical students: 66 in Quito (2,800 m altitude) and 40 in Guayaquil (sea level). At the end of the supplementation, there was a nearly complete disappearance of biochemical evidence of iron deficiency in the two groups of students. In Quito, 30% of the men and 26% of the women increased their hemoglobin concentration by more than 1 g/dl after one month of supplementation and could be considered as true anemics, compared to 31% of the men and 29% of the women in Guayaquil. This study shows that at sea level, cut-off points defined by WHO for hemoglobin, taking as reference the impact of a supplementation trial, have a specificity of 100% but poor sensitivity (58%). For people living at high altitudes, cut-off limits adjusted for altitude seem unsuitable: the specificity is 98% but the sensitivity is 0%. Studies taking into account all the factors impacting on the hemoglobin level could be useful for defining cut-off points for high-altitude anemia better than those currently recommended.

Adult↗