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Biomedical subjects

A Sanchez

Publications and source records attributed to A Sanchez.

At least 325 records · Page 18Linked to original sources
PubMedDate not supplied

Intrahepatic peripheral cholangiocarcinoma: CT evaluation.

BACKGROUND: The purpose of our study was to evaluate the imaging features and patterns of contrast enhancement in peripheral cholangiocarcinomas with computed tomography (CT) and correlate these features with histologic findings when available. METHODS: We reviewed the CT scans of 24 patients with 25 peripheral cholangiocarcinomas proved by orthotopic liver transplantation (n = 1), liver resection (n = 7), percutaneous needle biopsy (n = 10), and fine needle aspiration biopsy (n = 6). Incremental dynamic nonhelical CT was performed in four cases and helical CT in 21 cases. Portal venous phase images were obtained in all 25 cases. Fourteen patients underwent helical CT during arterial and portal phases. Delayed images were obtained in 20 patients. RESULTS: The size of the tumors ranged from 1.2 to 17 cm. Bile duct dilatation was present in 13 patients (52%), and regional lymph node enlargement was observed in six patients (24%). Retraction of the liver capsule was present in nine patients (36%). In eight patients (32%), satellite nodules were also detected. All tumors were globally hypodense during the portal phase. In 14 patients (70%), delayed images disclosed hyperattenuating tumors. Rimlike contrast enhancement was the most frequent pattern observed in either arterial (57% of patients) or portal (60% of patients) phase imaging. Portal venous encasement was seen in 10 patients (40%). CONCLUSION: In the proper clinical setting, detection of a hypodense hepatic lesion with peripheral enhancement, biliary dilatation, and contrast enhancement on delayed images are highly suggestive of peripheral intrahepatic cholangiocarcinoma.

Adult↗
PubMedDate not supplied

Diacylglycerol and phorbol ester stimulate secretion without raising cytoplasmic free calcium in human platelets.

An increase in cytoplasmic free calcium, [Ca2+]i, is thought to be the trigger for secretory exocytosis in many cells. In blood platelets, large rises in [Ca2+]i can cause secretion and calcium has been regarded as the final common activator not only for secretion but also for shape-change and aggregation. We have shown that while thrombin and platelet-activating factor (PAF) normally elevate [Ca2+]i, they can also stimulate shape-change and secretion even when the [Ca2+]i rise is suppressed. The present results strongly implicate diacylglycerol, produced by stimulus-dependent breakdown of phosphoinositide, in this calcium-independent activation. Exogenous diacylglycerol activates a protein kinase (C-kinase) in platelets as do PAF, thrombin and collagen. 12-O-tetradecanoyl phorbol-13-acetate (TPA) also activates C-kinase and is a potent stimulus for secretion and aggregation. It is shown here that the exogenous diacylglycerol 1-oleoyl-2-acetyl-glycerol (OAG) and TPA evoke similar secretion and aggregation without elevating [Ca2+]i above the basal level of 0.1 microM. The pattern of secretion resembles that produced by collagen and thrombin when [Ca2+]i remains at basal levels. Modest increases in [Ca2+]i, insufficient to stimulate secretion, markedly accelerate the responses to TPA and OAG.

Blood Platelets↗
PubMedDate not supplied

Genetic characterization of southwestern European bovine breeds: a historical and biogeographical reassessment with a set of 16 microsatellites.

The origin of Iberian cattle has been suggested by some authors to be the product of European and north African cattle entrances during the last few thousands of years. However, these hypotheses were mainly based on morphological similarities. This study analyzed 889 unrelated individuals from 15 representative Iberian breeds and 3 French breeds for 16 microsatellite loci. Statistical tests were used to calculate interpopulation genetic distances (D(A)) and principal components analysis (PCA). To visualize the geographical distribution of the genetic differentiation between Iberian cattle breeds, data from the PCA analysis were used to construct synthetic maps. Genetic similarity among neighboring Iberian breeds is mainly caused by gene flow. However, recent demographic fluctuations and reproductive isolation in Alistana, Mirandesa, and Tudanca has increased genetic drift, which may be the main cause for the relatively high differentiation of these populations. The synthetic maps constructed with the first and second PCs revealed (1) a large differentiation between Northern Iberian breeds rather than between more geographically distant breeds, and (2) a clear east-west gradient that may be related with the model of demic diffusion of agriculture. Finally, we detected no strong evidence for an African genetic influence in the Iberian cattle breeds analyzed in this study.

Africa, Northern↗
PubMedDate not supplied

Comparative F statistics analysis of the genetic structure of ten Spanish dog breeds.

The genetic structure and relationships among 10 Spanish dog breeds have been studied by using F statistics. Data came from 21 structural genic loci that codify for blood-soluble proteins and enzymes detected by electrophoresis. Of the 21 loci, 11 were found to be polymorphic. The study was done at three levels of hierarchical differentiation: ancestral trunks, breeds, and subpopulations. The deficit of heterozygotes was estimated at the subpopulation, breed, and ancestral trunk levels, with values of 4.0%, 6.5%, and 11.2%, respectively. In the whole population, the deficit of heterozygotes was about 17%. The proportion of genetic variability attributable to differences between subpopulations, breeds, and ancestral trunks was estimated to be 14.2%, 9.9%, and 6.9%, respectively. The dendrogram, obtained by using values of genic differentiation (FST) as a measure of the genetic distance among populations, is topologically identical to the one obtained using Nei's index of distance, which indicates a high correlation (r = .99) between both distances. These racial groupings, however, differ from the grouping obtained from historical, archeological, and morphological data.

Animals↗
PubMedDate not supplied

Melatonin therapy of advanced human malignant melanoma.

We undertook a study to investigate the therapeutic potential of orally administered melatonin in patients with advanced melanoma. Forty-two patients received melatonin in doses ranging from 5 mg/m2/day to 700 mg/m2/day in four divided doses. Two were excluded from analysis. After a median follow-up of 5 weeks, six patients had partial responses, six additional patients had stable disease. Sites of response included the central nervous system, subcutaneous tissue and lung. The median response duration was 33 weeks for the partial responders. There was a suggestion of a dose-response relationship. The toxicity encountered was minimal and consisted primarily of fatigue in 17 of 40 patients. Melatonin also appeared to reduce basal levels of follicle-stimulating hormone (FSH). No significant changes were encountered in serum levels of luteinizing hormone (LH) or thyroid stimulating hormone (TSH). We conclude that further study of melatonin as a potentially useful agent in metastatic melanoma is warranted.

Adolescent↗
PubMedDate not supplied

Genetic diversity measures of local European beef cattle breeds for conservation purposes.

This study was undertaken to determine the genetic structure, evolutionary relationships, and the genetic diversity among 18 local cattle breeds from Spain, Portugal, and France using 16 microsatellites. Heterozygosities, estimates of Fst, genetic distances, multivariate and diversity analyses, and assignment tests were performed. Heterozygosities ranged from 0.54 in the Pirenaica breed to 0.72 in the Barrosã breed. Seven percent of the total genetic variability can be attributed to differences among breeds (mean F(st) = 0.07; P<0.01). Five different genetic distances were computed and compared with no correlation found to be significantly different from 0 between distances based on the effective size of the population and those which use the size of the alleles. The Weitzman recursive approach and a multivariate analysis were used to measure the contribution of the breeds diversity. The Weitzman approach suggests that the most important breeds to be preserved are those grouped into two clusters: the cluster formed by the Mirandesa and Alistana breeds and that of the Sayaguesa and Tudanca breeds. The hypothetical extinction of one of those clusters represents a 17% loss of diversity. A correspondence analysis not only distinguished four breed groups but also confirmed results of previous studies classifying the important breeds contributing to diversity. In addition, the variation between breeds was sufficiently high so as to allow individuals to be assigned to their breed of origin with a probability of 99% for simulated samples.

Algorithms↗
PubMedDate not supplied

Joint effects of monomer and stabilizer concentrations on physico-chemical characteristics of poly(butyl 2-cyanoacrylate) nanoparticles.

A rotatable central composite design was applied to the formulation of poly(butyl 2-cyanoacrylate) nanoparticles with the aim of modifying some physico-chemical properties of these carriers in a controlled way. The joint effect of stabilizer concentration and monomer concentration on the mean particle size, on the electrophoretic mobility and on the polymer molecular weight has been investigated. The results demonstrate that the particle size is only dependent on the stabilizer concentration, nevertheless the electrophoretic mobility and the molecular weight distribution were affected simultaneously by the monomer and the stabilizer concentrations. Moreover, using the response surface diagrams it is possible to deduce the experimental conditions to design particles with the desired properties. Finally, the degradation rates for two different molecular weight formulations were compared, showing the relevance of this property.

Capsules↗
PubMedDate not supplied

Isolation and phylogenetic characterization of Ebola viruses causing different outbreaks in Gabon.

Three outbreaks of Ebola hemorrhagic fever have recently occurred in Gabon. Virus has been isolated from clinical materials from all three outbreaks, and nucleotide sequence analysis of the glycoprotein gene of the isolates and virus present in clinical samples has been carried out. These data indicate that each of the three outbreaks should be considered an independent emergence of a different Ebola virus of the Zaire subtype. As in earlier Ebola virus outbreaks, no genetic variability was detected between virus samples taken during an individual outbreak.

Animals↗
PubMedDate not supplied

[Emergency toxicology: analytic protocol applicable to biolobic media in tentative autolysis].

Here is exposed a method to detect and identify, without delay and in biological media, toxic substances generally found when attempting autolysis. It implies: 1; coloured reactions performed directly or after having isolated the substances using organic solvants, 2; thin layer chromatographies of these extractums which are developed and revealed in very precise conditions. Techniques for titration of some drugs are exposed. 253 cases of toxic coma have been studied, and the results of this inquiry analysed, more particularly cases induced by barbiturates.

Autolysis↗
PubMedDate not supplied

Quantitation of comparative thrombogenicity of dog, pig, and human platelets in a hemodialyzer.

Comparative platelet thrombogenicity was quantified with In111 labeled platelets. The platelets collected from the blood of Beagle dogs, Yorkshire pigs, and human volunteers were labeled with detergent free In111 tropolone, and sham hemodialysis (SHD) was performed with a hollow fiber dialyzer in a flow loop at 37 degrees C, with flow rates of 7, 150, and 270 ml/min. After SHD, hemodialyzer radioactivity was measured with an ionization chamber, gamma counter, and it was imaged with a gamma camera. The mean values of hemodialyzer-adherent platelet radioactivity were calculated. Canine platelets are more thrombogenic than porcine and human platelets. Quantitation of comparative thrombogenicity with In111 platelets may provide an estimation of prosthesis induced thrombogenicity of human platelets from animal studies.

Animals↗
PubMedDate not supplied

Profile of blood elements in leprosy patients.

Blood levels of 40 elements in 14 leprosy patients and 5 control subjects living near Mukinge Hospital in the North Western Province of Zambia were determined by spectrophotometry. In patients, compared to controls, serum levels of titanium, silicon, potassium and platinum were significantly higher; red cell levels of phosphorus were lower but those of antimony, bismuth, nickel, titanium, yttrium, silicon and platinum were higher; and whole blood levels of phosphorus, selenium, antimony and silver were lower. There were also significant differences in levels of certain elements when histologically active and inactive patients were compared and between the polar forms of leprosy. The data are consistent with a hypothesis of metabolic and nutritional involvement in the etiology of leprosy.

Adolescent↗
PubMedDate not supplied

Radiographic features of hereditary articular chondrocalcinosis. A comparative study with the sporadic type.

To assess the radiological features of hereditary articular chondrocalcinosis, we performed a blind comparative study between 21 randomly selected patients with hereditary disease and 21 cases of sporadic pseudogout matched for age and sex. Each individual had AP projections of the hands, pelvis and knees. The films were evaluated for the presence of articular chondrocalcinosis and for the severity of the associated degenerative arthropathy. A grade of 0 to 3+ was assigned to each of the 4 variables of osteoarthritis: joint space narrowing, sclerosis, osteophytosis and subchondral cysts. The mean number of joints with chondrocalcinosis and its distribution was similar in both groups. In addition, no differences were found in the overall severity of the associated degenerative arthropathy. In both groups the disease was characterized by oligoarticular calcification and a mild degenerative arthropathy. These data along with data from other reported pedigrees, show that the radiological appearance in the hereditary type is frequently indistinguishable from that commonly observed in sporadic articular chondrocalcinosis.

Aged↗