PubMed Health⌕ Search

Biomedical subjects

E Chavez

Publications and source records attributed to E Chavez.

At least 19 recordsLinked to original sources
PubMed2006

Breast tumor resembling the tall cell variant of papillary thyroid carcinoma: a case report.

The breast tumor resembling the tall cell variant of papillary thyroid carcinoma is a very unusual mammary carcinoma whose histologic and predominant nuclear features mimic a papillary thyroid carcinoma. We report the case of a 64-year-old woman who presented with a palpable nodule in the right breast. Fine needle aspiration disclosed abundant cellularity with isolated cells, sheets, and papillary formations of epithelial cells with nuclear grooves. Histologically, the neoplastic cells were arranged in a solid to papillary architecture, with follicular-like and cribriform areas. The cells were columnar to cuboidal with eosinophilic cytoplasm, clear chromatin, nuclear grooves, and occasional nuclear pseudoinclusions. Tumor cells were positive for cytokeratins, alpha and beta-estrogen receptors, progesterone receptor, androgen receptor, CEA, and bcl-2. We searched for BRAF mutations with negative results. Recognizing the cytologic and histologic characteristics of these peculiar mammary tumors that mimic thyroid carcinomas can avoid unnecessary clinical investigations.

Breast Neoplasms↗
PubMed2002

Nematodes as indicators of wetland pollution.

Since diversity suggests that changes in nematode populations or communities may be useful indicators of environmental changes including anthropogenic disturbances, in this study the following measurements were done: pH, predominant plant taxa, nematode density and diversity at different wetland points along La Tapera creek. A random sampling was carried out and data were subject to analysis t-test. In this work, neither the diversity nor the pH changed, however the latter was high and nematode density and taxa were small but without significative oscillations between stations. However, other population indices showed consistent differences between sites, which are pointing out environmental alteration throughout the creek. These preliminary results from the wetland present a description of nematode communities existing under a particular set of conditions that have not been reported previously.

Animals↗
PubMed2001

Gastric permeability is not increased in children colonized by CagA-positive strains of Helicobacter pylori.

BACKGROUND: Sucrose permeability has been used as a marker to detect gastric lesions in children. As CagA status of Helicobacter pylori is an important factor in determining the evolution of the gastric lesion, CagA-positive strains being more frequently associated with severe mucosal lesions, the aim of this study was to determine the prevalence of CagA-positive strains in Helicobacter pylori-colonized children and to evaluate whether the sucrose permeability test might discriminate between colonization by CagA-positive or negative strains. PATIENTS AND METHODS: A series of 38 children (11.1+/-3.6 years) who required upper endoscopy for diagnostic purposes were included in the study. Endoscopy was carried out after the sucrose permeability test, and gastric biopsies were obtained for histologic examination, Helicobacter pylori detection by Giemsa staining and CLO-test, and determination of CagA status of the colonizing Helicobacter pylori strains by polymerase chain reaction. RESULTS: Helicobacter pylori was detected in 26 subjects (68.4%) and of these, 16 (61.5%) were colonized by CagA-positive strains. The intensity of the histologic findings was significantly associated with the presence of Helicobacter pylori and with CagA status of the infecting strains (chi2=21.2, p=0.0017). However no significant difference in the urinary excretion of sucrose between children not colonized and children with CagA- negative or positive strains was observed (0.027% [0.012-0.035%]; 0.027% [0.016-0.047%] and 0.026% [0.016-0.038], median [range], respectively; Kruskal-Wallis analysis of variance F=0.75, p=0.69). CONCLUSIONS: These results indicate that in Chile, about 60% of the Helicobacter pylori infected children are colonized by CagA-positive strains, in association with more intense lesions of the gastric mucosa, but that gastric permeability to sucrose does not discriminate between colonization by CagA-negative and positive strains of Helicobacter pylori.

Abdominal Pain↗
PubMed1999

Bedside markers of coronary artery patency and short-term prognosis of patients with acute myocardial infarction and thrombolysis.

BACKGROUND: In this study we have evaluated the prognostic power of noninvasive markers of coronary artery reperfusion in patients with acute myocardial infarction who were treated with intravenous streptokinase. METHODS: In 967 consecutive patients with acute myocardial infarction who were treated within 6 hours of symptoms, we analyzed the prognostic power of resolution of chest pain and ST-segment elevation >50% at 90 minutes, abrupt creatine kinase rise before 12 hours, and T-wave inversion in infarct-related electrocardiographic leads within the first 24 hours after thrombolysis. RESULTS: Global in-hospital mortality rate was 12.0%. Each reperfusion marker was associated with improved outcome. Multivariate logistic regression analysis showed that 3 of the 4 markers of coronary artery reperfusion were significantly and independently associated to low in-hospital mortality rate. The presence of early T-wave inversion was associated with the lowest in-hospital mortality rate (odds ratio 0.25, confidence interval 0. 10-0.56). When all markers of coronary artery reperfusion were included in the regression model, T-wave inversion (odds ratio 0.29, confidence interval 0.11-0.68) and abrupt creatine kinase rise (odds ratio 0.36, confidence interval 0.16-0.77) continued to be significantly associated with better outcome. CONCLUSION: A systemic analysis of noninvasive markers of coronary artery reperfusion can provide the clinician with an excellent tool to predict clinical outcomes when treating myocardial infarction.

Aged↗
PubMed1997

Further studies on the recoupling effect of 6-ketocholestanol upon oxidative phosphorylation in uncoupled liver mitochondria.

The effect of 6-ketocholestanol was studied on CCCP-induced uncoupling in liver mitochondria, submitochondrial particles and cytochrome oxidase proteoliposomes. It was found that 6-ketocholestanol prevents and reverses uncoupling induced by nM concentrations of CCCP on the three systems assayed. As it was reported on kidney mitochondrial membranes [Chavez et al. (1996) FEBS Lett. 379, 305-308], the recoupling effect caused by 6-ketocholestanol on submitochondrial particles and proteoliposomes could be due to a diminution of membrane fluidity.

Animals↗
PubMed1997

Telomeres in the haemopoietic system.

The limited life span of most blood cells requires the continuous production of cells, which in adults exceeds 10(12) cells/day. This impressive production of cells (approximately 4 x 10(16) cells over a lifetime) is achieved by the proliferation and differentiation of committed progenitor cells, which themselves are derived from a population of pluripotent stem cells with self-renewal potential. Paradoxically, the large majority of stem cells in adult bone marrow are quiescent cells. One possibility is that stem cells, like other somatic cells, have only a limited replicative potential (< 100 divisions). This hypothesis is supported by two key observations and the consideration that, in theory, 55 divisions can yield 4 x 10(16) cells. First, it was shown that 'candidate' stem cells purified from fetal and adult tissue showed dramatic functional differences in turn-over time and the ability to produce cells with stem cell properties, Second, these functional differences were found to correlate with a measurable loss of telomere repeats despite the presence of low but readily detectable levels of telomerase in all purified cell fractions. In order to address questions about the role of telomeres in normal and malignant haemopoiesis, we developed a quantitative fluorescence in situ hybridization technique. Here we review the characteristics of this novel tool to assess the number of telomere repeats at the end of individual chromosomes and provide an overview of recent observations.

B-Lymphocytes↗
PubMed1997

Sucrose permeability in children with gastric damage and Helicobacter pylori infection.

BACKGROUND: Increased permeability to sucrose has been recently shown to be a good marker of gastric mucosal damage in adults. METHODS: This test was evaluated in 40 children consulting for recurrent abdominal pain and the results were correlated with endoscopic and histologic findings and with the presence of H. pylori. RESULTS: The gastric mucosa was considered endoscopically normal in 31 children; 3 had duodenitis and 6 had mild gastritis. Abnormal endoscopic findings were associated with increased urinary sucrose excretion (MANOVA F = 7.30; p = 0.002). In the 6 children with mild gastritis, mean sucrose excretion was twice that of controls (0.060 +/- 0.024 vs. 0.029 +/- 0.018, respectively; p = 0.019) and significantly higher than the group with duodenitis (0.037 +/- 0.013; p = 0.038). The specificity and sensitivity of sucrose permeability test for detection of gastric damage were 90.3% and 83.3%, respectively. H. pylori was detected in 62.5% of children including all patients with mild gastritis, in 2 out of 3 with duodenitis and 17 out of 31 endoscopically normal controls. No differences in sucrose excretion were observed in relation with the presence of H. pylori or histological findings in the control group. CONCLUSIONS: Urinary sucrose excretion is a good marker of mucosal gastric damage in children and may be used as a screening test in large groups of populations.

Abdominal Pain↗
PubMed1989

Induction of mitochondrial Ca2+ uptake by mersalyl.

1. The addition of mersalyl to aged mitochondria from rat kidneys, is followed by induction of an ATP-driven Ca2+ uptake which is sensitive to Ruthenium Red. 2. This Ca2+ influx requires Mg2+, albumin, and is accomplished by membrane energization. 3. The activation of Ca2+ uptake by the mercurial in the presence of ATP can be explained if it is assumed that the inorganic phosphate generated by ATPase activity, and trapped in the matrix by the thiol reagent, provides the negative potential which results in an electrophoresis cation influx.

Adenosine Triphosphate↗
PubMed1988

Effects of an NADPH-generating system on primaquine degradation by hamster liver fractions.

1. Primaquine (PQ) often causes severe anaemia in individuals with glucose 6-phosphate dehydrogenase (G6PD) deficient erythrocytes, and metabolites have been implicated as the toxic substance. These studies present data identifying additional metabolites of PQ. 2. Two metabolites of primaquine (PQ) previously identified in human studies, namely, 6-methoxy-8-aminoquinoline (MAQ) and 8-(3-carboxy-1-methylpropylamino)-6-methoxyquinoline (PQC) were also formed on incubation of PQ with hamster liver fractions for up to 24 h without an NADPH-generating system. 3. The alcohol (PQAOH) and lactam (PQLT) derivatives of PQ were also formed on incubation with hamster liver fraction used in these studies. 4. The microsomal metabolism of PQ was decreased in presence of an NADPH-generating system, but not by SKF-525A or glutathione (GSH) indicating that the oxidative reactions were probably not due to the cytochrome P-450 system or free radical mechanisms.

Animals↗
PubMed1983

Cardiac rehabilitation after acute myocardial infarction. 9-year controlled follow-up study.

Since the effect of cardiac rehabilitation (CR) on morbidity and mortality due to myocardial infarction on a long-term basis appears controversial, a controlled follow-up survey was conducted from 1973 to 1981 in 193 patients suffering a first acute myocardial infarction (AMI). The admission criteria included absence of contraindications to CR during the acute phase of AMI. Patients were divided into two matched groups: 93 patients followed a CR program, exercising 30 min three times a week (means 42; range 6-108 months) and the remaining 100 patients served as controls. Age, sex, location and extension of the myocardial damage, frequency of coronary risk factors and complications during the acute phase were comparable. At 9 years, there were 24 cardiac deaths (15 AMI, 7 sudden deaths and 2 heart failures) among the controls and 13 deaths in the CR group (7 AMI, 4 sudden deaths, 2 heart failures), mortality rates being 5.2 and 2.9% per year (p less than 0.1 greater than 0.05; NS), respectively. There were 23 recurrent AMI in the control versus 16 in the CR patients, the corresponding rates being 4.9 and 3.6% per year, respectively (NS). Nor were any differences observed in the incidence of myocardial ischemia, severe arrhythmias or cerebrovascular strokes between both groups, but the appearance of angina was significantly lower in the CR group compared with the controls (5.1 and 10.2% per year, respectively, p less than 0.005). It is concluded that CR on a long-term basis seems to improve the mortality rate of AMI and to reduce the frequency of anginal pain.

Adult↗