Publications by authors named "MEDINA V"

Volvulus of the small bowel without predisposing anatomical defects is a rare cause of acute intestinal obstruction in the Western world, and its incidence is decreasing in Europe and America, although it is common in others parts of the world. The causes of primary volvulus of the small bowel and the mechanism of rotation of the entire root of the mesentery remain unexplained. Several anatomical and dietary factors have been implicated.

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We subcloned various constructs of the beet western yellows luteovirus (BWYV) 3' proximal genes into Bombyx mori nuclear polyhedrosis virus (BmNPV) transfer vectors and constructed recombinant BmNPVs. The recombinant BmNPVs were used to infect BmN cells and B. mori larvae.

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This laboratory has previously reported that the maternal opioid analgesia associated with pregnancy and parturition is mediated, at least in part, by a maternal spinal cord dynorphin/kappa opioid system. This analgesia is accompanied by an increase in dynorphin peptides (1-17 and 1-8) in the lumbar spinal cord. Levels of trypsin-generated arginine6-leucine-enkephalin (Leu-Enk-Arg)-immunoreactive determinants were also determined and used to reflect the content of dynorphin precursor intermediates.

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Upper digestive bleeding caused by an isolated gastric hemangioma is a rather rare occurrence, even in cases of Osler-Weber-Rendu syndrome. The case reported here, which brings to 40 the number reported in the world literature, is that of a 68-year-old patient who presented with upper digestive bleeding. Endoscopy led us to suspect a hemangioma due to the abnormally large lesion, a suspicion that was confirmed preoperatively through arteriography, which detected a hypervascular mass of 6 x 4 cm dependent on the gastroduodenal artery.

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Volvulus of the transverse colon is rare, given its short and fixed mesentery and the normal fixation of the hepatic and splenic flexures of the colon. The case reported herein brings the total of reported cases to 72. Various predisposing factors have been identified, most notably congenital abnormalities, physiologic disturbances and mechanical obstruction; in our case these three factors were present.

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A method for producing rapid and accurate scalp electroencephalography, evoked potential and current density mapping is described. This method is based on the spherical spline interpolation, which has been validated as the most suitable function for this application. In comparison with the basic algorithm, the proposed technique is accurate and fast: it reduces the computation time by a factor of 10, while preserving the desired precision level.

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A study of visual evoked responses in a normal population was carried out using a high-precision programmable stimulator and an innovative brain mapping system which presents the overall activity on a three dimensional surface representing the human head. The interpolation method used gives a more precise computation of the potential value between electrodes. Two normal distributions of visual responses are presented which were identified while trying to topographically characterize visual evoked responses in order to construct a comparative data base.

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Brain topography mapping is a useful technique for the representation of electrical activity recorded on the scalp. It clarifies spatial and temporal relationships between different cortical areas. In this work we propose a system which includes several enhancements over those previously proposed, such as an optimised interpolation method and a three dimensional reconstruction of maps.

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This article describes the first case in Mexico of an implantable pacer-cardioverter-defibrillator in a 44-year-old man with coronary artery disease and recurrent ventricular tachycardia without the need for a thoracotomy and epicardial electrodes. The patient underwent electrophysiological evaluation that revealed drug-refractory ventricular tachycardia. Endocardial catheter ablation with radiofrequency was considered and rejected due to an unstable hemodynamic state during the tachycardia.

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The histological and ultrastructural features, as well as the immunoreactivity of one case of uncommon primary papillary and psammomatous adenocarcinoma of the umbilicus are studied in the present work. The observations have been undertaken in a nine-year follow-up, and have included the primitive tumour, two local recidives, and inguinal lymphatic metastasis on two occasions. Papillary structures, numerous psammoma bodies, as well as weak and focal positive reactions to CEA and cytokeratin were present in all the tumours.

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In laboratory animals and humans, pregnancy is associated with opioid-mediated elevations in the threshold for responsiveness to aversive stimuli. Previous pharmacological analysis has demonstrated that this analgesia results, at least in part, from the activation of spinal cord kappa opioid receptors utilizing dynorphin as the major opioid substrate. The present report demonstrates that during late pregnancy, the content of spinal dynorphin A(1-17 and 1-8) is altered in a region-specific fashion.

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Pregnancy and parturition are associated with opioid-mediated elevations in maternal pain thresholds. This analgesia is subserved by a spinal cord dynorphin/kappa-opiate receptor system. During gestation, elevated pain thresholds are paralleled by a significant increase in the content of dynorphin (1-17 and 1-8) in the lumbar spinal cord.

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Bacitracin is commonly used in metabolic studies as an insulinase inhibitor. The many isoforms of the commercial preparation were fractionated by charge and size in order to find the most active rat-muscle insulinase inhibitors. CM-Sepharose chromatography revealed that most of the inhibitory activity was contained in a fraction (CM-Inh) that amounted to less than 5% of the mixture.

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Ribonucleoprotein particles (RNPs) of rice hoja blanca virus (RHBV) were purified and used for electron microscopic analysis and antibody production. Antibodies made to RNPs specifically decorated purified RNPs. The RNPs typically showed characteristic tenuivirus morphologies.

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The time course, kinetic, specificity and sodium-dependence of L-leucine and L-phenylalanine uptake by rabbit isolated oxyntic glands were studied in order to identify the systems involved in the transport of branched-chain and aromatic neutral amino acids through the basolateral cell membrane. The uptake was measured directly in the disrupted cells after incubation of the glands with the 3H-labelled amino acid both in a sodium-containing and a sodium-free medium. The uptake of L-leucine was largely carrier-mediated whilst L-phenylalanine was taken up by either carrier-mediated and nonsaturable processes.

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The cauliflower mosaic virus ORF II encoding the aphid transmission factor (ATF) was mutagenized to introduce a BamHI restriction site upstream from the initiation codon and then cloned into an eukaryotic viral expression vector (Autographa californica nuclear polyhedrosis virus). All recombinant viruses tested in Spodoptera frugiperda (SF21) cells expressed a protein of about 18 kD which comigrated in PAGE with ATF from infected plants. Western blotting using an oligopeptide antiserum to ATF confirmed the identity of the 18-kD protein from infected cells as the product of the ORF II sequences (P18).

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Turnip leaves infected with the aphid transmissible isolate of cauliflower mosaic virus (CaMV Cabb B-JI) showed two types of virus-containing inclusion bodies (IBs), which differed morphologically and in their protein composition when analyzed by immunogold labeling of ultrathin sections. Vacuolated IBs, typical of CaMV infections, contained P62 (the generally accepted IB protein) but lacked P18 (the aphid transmission factor), while electron-lucent IBs did not contain P62 but were the only detectable sites of P18 accumulation within the infected leaf cells. Both types of inclusions were detected in cells of the epidermis, vascular bundles, mesophyll, and spongy parenchyma.

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Surgical management of patients with acute colonic diverticulitis is evolving from multiple towards single operations. The patterns of presentation and treatment of 146 patients with acute perforated diverticulitis have been reviewed (1983-1988) using the Hinchey classification system (Stages I-IV). This paper focuses on the six patients who presented with fecal peritonitis (Stage IV disease), half of whom were treated by primary resection and anastomosis and the remainder by a Hartmann procedure.

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The sequence of the pckA gene coding for phosphoenolpyruvate carboxykinase in Escherichia coli K-12 and previous molecular weight determinations indicate that this allosteric enzyme is a monomer of Mr 51,316. The protein is homologous to ATP-dependent phosphoenolpyruvate carboxykinases from Trypanosoma brucei and Saccharomyces cerevisiae. A potential ATP binding site was conserved in all three sequences.

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An 8 kb BamHI fragment of the Escherichia coli K12 chromosome has been cloned which complemented the pheotype of CRM+ pckA mutants with inactive phosphoenolpyruvate (PEP) carboxykinase. The pckA+ clones expressed levels of enzyme activity elevated up to 30-fold and produced a Mr 55,000 product in maxicells, which co-electrophoresed with purified PEP carboxykinase. The cloned fragment expressed the pckA, ompR and envZ gene products in maxicells.

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A posttest-only control group design was used to study the effects of two electrode site preparation techniques on reducing electrical potential across a pair of disposable skin electrodes. Sixty health volunteers were randomly divided into one control and two treatment groups of 20 subjects each. Within each group, the treatment was further assigned randomly to either the right or left forearm.

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Antibodies that recognize unmodified heparin bound to positively charged macromolecules have been obtained by immunizing rabbits with a methylated bovine serum albumin-heparin precipitate. These antibodies have been used to develop an immunoassay that can quantitate heparin at a concentration of 5 ng/ml in buffer solutions, and at a concentration of 25 ng/ml in plasma without pretreatment of the sample. The specificity of the antibodies is such that they do not recognize other glycosaminoglycans and are able to distinguish among different commercial heparin samples that are otherwise indistinguishable by specific anticoagulant activity or molecular weight distribution.

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Sustained ventricular tachycardia (VT) develops in many patients with chronic Chagasic myocarditis. Programmed stimulation was used to study the electrophysiologic characteristics of VT in 15 patients with Chagas' cardiomyopathy. Nine patients were in New York Heart Association functional class I, 5 were in class II and 1 patient was in class III.

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Protein-heparin complexes, prepared by a water-soluble carbodiimide coupling technique, were used to produce anti-heparin antibodies in rabbits. Antiserums that recognized carbodiimide-treated heparin, but not untreated heparin, were obtained. Carbodiimide-treated heparan sulfate exhibited 10% to 20% cross-reactivity compared with a similarly treated heparin, whereas there was no cross-reactivity with five other carbodiimide-treated mucopolysaccharides.

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