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Biomedical subjects

R Segal

Publications and source records attributed to R Segal.

At least 217 records · Page 12Linked to original sources
PubMed1982

Implanted pulsatile balloon device for simulation of neurovascular compression syndromes in animals.

A self-contained neurovascular compression simulator (NCS) has been designed to function as an artificial artery that pulsates with the heart. When implanted in animals, this device simulates those naturally occurring situations in which there is compression of nervous elements in the region of the brain stem or other areas by aberrant, or ectatic branches of normal arteries. The NCS consists of an intra-aortic balloon, a smaller (cephalic) balloon, a connecting tube, and an injection port, all fabricated of polyurethane-silicone compounds. With each heart systole, the rise in intra-aortic pressure is transmitted to the smaller cephalic balloon in the form of a pulsation. Thus, part of the cardiac ejection energy is transferred to the desired nervous structures. The performance of each NCS is tested in vitro in a pulse duplicator system. The NCS was chronically implanted for up to 2 years in four dogs and 10 baboons. The cephalic balloon was placed intracranially in the subarachnoid space on the ventrolateral medulla adjacent to the entry zone of the ninth and 10th cranial nerves on the left side of baboons and on the right side of dogs. The position of the balloons was checked by fluoroscopy. Following implantation, the NCS could be inflated or deflated at will using the injection port which served to restart or discontinue the pulsations. No occlusion of the aorta or reduction of blood flow to the lower limbs or trunk was detected. By means of the NCS, an experimental model of neurogenic hypertension was produced in baboons.

Animal Diseases↗
PubMed1982

Prescribers' beliefs and values as predictors of drug choices.

A cognitive model of the drug-prescribing process, which incorporates prescribers' attitudes (valences) about treatment outcomes and beliefs (instrumentalities) about drug effects, was tested. Twelve physicians were interviewed to identify common outcomes associated with drug therapy; six distinct outcomes were identified. Then 50 family practice residents were given a hypothetical description of a mildly hypertensive patient and three treatment choices. The physicians completed a questionnaire that identified (1) the instrumentalities of each of the alternative treatments for each of the six outcomes and (2) the valences for each outcome. The physicians were also asked to respond to an open-ended question on how they would treat the patient described in the case. Forty-six physicians proposed 39 treatments that corresponded to the three treatments for which instrumentalities and valences were available. The drug-choice model correctly predicted 28 of 39 (72%) therapeutic decisions, which was significantly more than would be expected by chance (p less than 0.01). Both valences and instrumentalities appear important for predicting prescribing intention. Pharmacists can use this model in their attempts to influence prescribing.

Attitude of Health Personnel↗
PubMed1981

Hemolysis caused by polyoxyethylene-derived surfactants. Evidence for peroxide participation.

The hemolytic properties of nonionic surfactants of the series CH3(CH2)15-17-O-(CH2CH2O)nCH2CH2OH were investigated and compared to those of saponins, sapogenins and H2O2. Antioxidants and anaerobic conditions were shown to inhibit the hemolysis, while glycyrrhizin was found to enhance it. Similar effects were obtained for H2O2 hemolysis, but not for saponin and sapogenin hemolysis. It is proposed that peroxides and free radicals are mainly responsible for the polyoxyethylene derived surfactants induced hemolysis.

Animals↗
PubMed1981

On the mechanism of ribonucleoside triphosphate reductase from Lactobacillus leichmannii. Evidence for 3' C--H bond cleavage.

The 3' carbon-hydrogen bond of [3'-3H]uridine 5'-triphosphate is is cleaved during its conversion to 2'-deoxyuridine 5'-triphosphate catalyzed by Lactobacillus leichmannii ribonucleoside triphosphate reductase. A selection against 3H of approximately 1.8 is observed on this reduction. During the course of this reaction, no 3H is released to the solvent, and no 3H is recovered in reisolated coenzyme B12. Incubation of [3'-2H]uridine 5'-triphosphate with enzyme resulted in production of 2'-deoxy[3'-2H]uridine 5'-triphosphate.

Carbon Radioisotopes↗
PubMed1981

Lymphocyte transformation in competent and in immunodepressed individuals. 3 ways of results presentation.

Lymphocytes from 107 healthy individuals and 34 patients with lung cancer were cultured and stimulated with PHA. Wide variation in lymphocyte transformation reactivity was observed, ranging from significantly low responses to high blastogenesis. Low spontaneous blastogenic responses were not always associated with a simultaneous decrease in PHA-induced lymphocyte transformation in the same individuals. The results are presented by the (disintegrations per minute) values of the stimulated and nonstimulated cultures and by the stimulation index. A new index termed the Blastogenic Cumulative Index is proposed. It is defined as the sum of the logarithms of the values of the spontaneous and the PHA-induced lymphocyte transformation. A better relationship was observed in immunocompetent and in immunodepressed individuals between the dpm values and Cumulative Indices than between the dpm and the Stimulation Indices.

Cells, Cultured↗
PubMed1981

HLA antigens in Jews with pemphigus vulgaris.

The association of HLA antigens with pemphigus in Jewish patients of various ethnic origins was investigated. Of 45 Ashkenazi patients, 31 (68.6%) had A26 (p less than 10(-5) and 32 (7175) had BW38 ( less than 10(-5)0. Among the 11 non-Ashkenazi patients, 7 (63.6%) had A26 and only 1 had BW38. The question whether the antigen A26 or BW38 is linked with the disease is discussed. Our findings may suggest that the primary association of pemphigus is with A26. This association may be stronger in Jewish male patients than in females. In view of the recent literature and our results it may be presumed that pemphigus in Jews is associated with antigens of Loci A and DR. No differences between pemphigus vulgaris and pemphigus erythematosus were observed.

Adult↗
PubMed1981

Spinal subdural hematoma associated with anticoagulant therapy in a patient with spinal meningioma.

A case of spontaneous subdural hematoma in the cervicothoracic region associated with a small meningioma in a patient on anticoagulant therapy is presented. The neurological complications of anticoagulant therapy are discussed briefly. Progressive neurological deterioration in a patient on anticoagulant therapy should prompt the performance of an emergency myelogram and a possible laminectomy in spite of the potential risks of these procedures. Intraspinal bleeding occurs more frequently in the form of an epidural hematoma, but the clinical presentation may not allow differentiation from a subdural hematoma. The possible causal relation between the asymptomatic spinal meningioma, the anticoagulant therapy, and the formation of the subdural hematoma is discussed.

Female↗
PubMed1981

Plasma dopamine beta hydroxylase activity in chronic schizophrenic patients tested with single dose of 2-bromo-alpha ergocriptine (Parlodel).

Plasma dopamine beta hydroxylase (D.B.H) activity was measured in 6 chronic schizophrenic patients. Treated with phenothiazine and butyrophenone derivatives after administering a single dose of bromocriptine (7,5 mg) orally, and compared to a matched group of 6 chronic treated schizophrenic patients without bromocriptine loading, and to a control matched group loaded with 7.5 mg of bromocriptine. A significant difference was observed in D.B.H. plasma levels of the schizophrenic patients group who received bromocriptine, by comparison with the other two control groups.

Administration, Oral↗
PubMed1980

Studies of fibronectin matrices in living cells with fluoresceinated gelatin.

We have used fluorescein isosthiocyanate-conjugated gelatin (FITC-gelatin) (1 mg/ml) to localize cell surface fibronectin in unfixed live cells in cultures. FITC-gelatin stains the fibronectin matrix on primary cultures of rat and chick embryo fibroblasts as well as untransformed, established cell lines. In live cultured cells, fibronectin in many areas of the extracellular matrix is inaccessible to antibody and cannot be visualized by immunofluorescence staining. In contrast, fibronectin in these areas is fully stainable by FITC-gelatin. At a low concentration (20 micrograms/ml), FITC-gelatin stains the fibronectin matrix of primary cultured cells but not of "untransformed" established cell lines. SEM can detect only the matrix stainable with the low concentration of FITC-gelatin, such as that expressed by primary chick embryo fibroblasts. The binding of fibronectin to the extracellular matrix is very stable and FITC-gelatin remained bound to the matrix for at least 10 d in culture. Radioiodinated gelatin has been used to quantitate the level of cell surface fibronectin in living normal and transformed cells. FITC-gelatin appears to be a useful probe for studying the fibronectin of living cells in culture.

Animals↗
PubMed1980

Xenon- and iodine-enhanced CT of diffuse cerebral circulatory arrest.

The role of contrast-enhanced computed tomography (CT) was evaluated in three nonhuman primates with a severe cerebrovascular insult and resulting elevated intracranial pressure and diffuse circulatory arrest. In all three animals the brain vasculature did not opacify after the bolus intravenous injection of iodinated contrast media. In addition, the brain substance did not enhance although the arterial blood enhanced normally after inhalation of a high concentration of xenon. Xenon-enhanced CT scanning, like 133Xe radionuclide scanning, may be used to define the absence of generalized cerebral perfusion.

Animals↗