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Biomedical subjects

R Levy

Publications and source records attributed to R Levy.

916 records · Page 51Linked to original sources
PubMedDate not supplied

Heterogeneity of human monocytes: differences in response to IFN-gamma.

Human peripheral blood monocytes can be separated into two subpopulations which differ in the efficiency of their adherence to glass after 16 hours of incubation. The adherent subpopulation was found to be about twice as effective in binding mannose-resistant E. coli 0-124, mannose-sensitive E. coli 0-128 and opsonised E. coli than the nonadherent one. In addition, reduction of cytochrome C in response to E. coli binding or 12-myristate 13-acetate (PMA) stimulation was two fold higher in adherent cells. The binding of E. coli O-124 and the superoxide generation stimulated by E. coli were inhibited by the addition of mannose only in the adherent monocytes, indicating the presence of mannose receptors on the cell surface in the adherent subpopulation. The treatment of the nonadherent cells with 0.1-1000 U/ml of Interferon (IFN-gamma) for 24 hours resulted in a dose dependent increase in superoxide generation. After 72 hours of incubation with IFN-gamma (1000 U/ml) the amount of superoxide generated by the nonadherent cells was elevated to 20.5 +/- 1.4 nmoles/10(6) cells/15 min, similar to that of the adherent cells (24.5 +/- 1.2 nmoles/10(6) cells/15 min untreated adherent monocytes). The generation of superoxide in the IFN-gamma treated nonadherent monocytes stimulated by E. coli 0-128 was significantly reduced by addition of mannose.

Bacterial Adhesion↗
PubMedDate not supplied

Elevated virulence of Newcastle disease virus strains following serial passages in kidney cells in vitro.

Serial passage of two lentogenic Newcastle disease virus (NDV) strains in kidney cell lines increased virulence and changed viral biological properties. In two cell lines (BHK and MDBK), elevation in virulence was demonstrated by plaque formation under an overlay with no additives, decrease in mean death times, elevated intracerebral pathogenicity index, and cytopathic effect in chicken embryo fibroblasts. Some other markers not directly correlated to virulence, such as heat inactivation of hemagglutinin and neuraminidase, were not influenced by passage in kidney cells. In addition, all strains were slow eluters. This observation emphasizes the importance of preventing the virus from reaching the viscera.

Animals↗
PubMedDate not supplied

Thyroid carcinoma in children and adolescents.

Carcinoma of the thyroid gland, although fairly common in young adults, is uncommon in the first two decades of life. Because therapy is controversial, it is important to study a relatively large group of patients treated in a single department. This report records the findings and responses to treatment in 40 cases of thyroid gland carcinoma in children and adolescents treated from 1953 to 1982.

Adolescent↗
PubMedDate not supplied

MR of myelomatous meningitis.

In a 56-year-old woman with multiple myeloma involving the leptomeninges diffusely, MR of the spine showed multiple vertebral compression fractures and marked enhancement of the cauda equina region. Intracranial MR showed pathologic enhancement of the left third and fifth cranial nerves.

Cauda Equina↗
PubMedDate not supplied

[Farnesyl transferase inhibitors (anti-Ras). A new class of anticancer agents].

Ras genes are frequently activated in human tumours. The role of their product, the P21 proteins, in the transduction of the mitogenic signal makes them attractive targets for an anti-neoplastic therapy. The p21 ras proteins are linked to the plasma membrane and transformed into an active form for signal transmission. Their effect is to mediate the effects of growth factors. Two drug families, the Benzodiazepine peptidomimetics and the CAAX tetrapeptides which inhibit the farnesylation of P21-Ras proteins abolish the transforming properties of mutated P21. These promising drugs could rapidly have clinical applications. They have been shown to be highly active at precise concentrations on ras-transformed cells but at the same concentrations are not toxic for untransformed cells. They do not effect other similar enzyme systems within the cell, underlining their selective capacity. Theoretically anti-ras therapy could only suspend cell transformation although it might be possible that if given long enough, a lethal threshold could be reached.

Alkyl and Aryl Transferases↗
PubMedDate not supplied

A role of transforming growth factor-beta 1 in the control of corneal neovascularization.

Transforming growth factor beta 1 (TGF-beta 1) has been implicated in both the stimulation of angiogenesis in vivo and in the inhibition of endothelial cell proliferation in vitro systems. In this study we present evidence showing that under certain experimental conditions TGF-beta 1 may inhibit neovascularization in vivo. TGF-beta 1 was incorporated into ethylene vinyl acetate copolymer (Elvax 40) matrixes which provide a valuable vehicle for the controlled and sustained delivery of bioactive peptides. The biological effectiveness of TGF-beta 1 sequestered in polymer matrices was assessed by measuring the inhibition of [3H]-thymidine incorporation into the DNA of cultured mink lung epithelial cells. Neovascularization was induced in both corneas of albino rabbits by one deep-seated limbal silk suture. Elvax 40 matrixes loaded with TGF-beta 1 (release rate, 1.66 ng/24 h) were implanted in rabbit corneal stroma. "Empty" polymers in the contralateral eye served as controls. Aliquots of aqueous fluid were withdrawn, and the presence activity of phagocytic cells was assessed by the production of superoxide anion (O2) which was measured by the superoxide dismutase-inhibitable reduction of ferricytochrome C. Polymer-enclosed TGF-beta 1 implanted in rabbit corneas significantly suppressed angiogenesis (2.65 +/- 0.4 mm compared to 3.05 +/- 0.3 mm in contralateral controls p < 0.05). Superoxide production in 100 microliters aliquots of aqueous fluid was 0.95 +/- 0.18 and 0.6 +/- 0.18 nmol O2/10 min in control eyes and in the eyes bearing sequestered TGF-beta 1, respectively (p < 0.02). These results indicate that under the experimental conditions selected in this study, TGF-beta 1 significantly suppressed in vivo angiogenesis.

Animals↗
PubMedDate not supplied

Clinicopathological trends in colorectal carcinoma in a Black South African population.

The clinico pathological characteristics of colorectal carcinoma in 127 Black South African patients were studied. The main presenting symptoms were altered bowel habits in 70% of the patients, weight loss in 64.3% and abdominal pain in 47.1%. Anaemia was present in 75.7%. There was a 31% incidence of mucinous carcinoma with a particular predilection for the younger age groups. Mucinous tumors were found more commonly in Duke stage C and D than in earlier stages. Tumors arising from a pre-existing adenoma constituted to 5.5% of the lot of patients with cancer colon.

Adenocarcinoma↗
PubMedDate not supplied

[Veno-venous hemofiltration with controlled ultrafiltration].

We haven't been using continuous veno-venous hemodiafiltration in our unit as an extrarenal depuration technique since 1991. With this work we want to provide our experience in what we call controlled ultrafiltration, technique which we have been using more frequently in the last two years and which consists on using the venous bomb of double head for ultrafiltration (UF) extraction, managing to obtain a more accurate control of it. The development of this technique has allowed us to obtain a higher control of the patient, reduce the risk of hypothermia and reduce the nursing burden. We show the procedure of priming, connection, disconnection and the necessary material, as well as the advantages and specific care we perform in our unit.

Anticoagulants↗
PubMedDate not supplied

Applications of laser scanning confocal microscopy to the observation of human oocytes and embryos.

Laser scanning confocal microscopy (LSCM) is a powerful and useful tool in developmental biology. The diverse applications of LSCM in biomedical field has led to advances in the microscopes themselves and the synthesis of novel specific probes for the observation of biological structures and the hypothesis of physiological process. LSCM was used to visualize the cellular actin cortex together with the chromatin in human arrested preimplantation embryos and in unfertilized oocytes obtained by in vitro fertilization. In embryos, we observed a majority of multinucleated blastomeres and some with fragmented nuclei or anucleated. LSCM also showed nuclei displaying the chromatin condensation and fragmentation patterns suggesting the phenomenon of apoptosis. Moreover, in arrested fragmented embryos of poor morphology, unequal sized blastomeres often showed cellular fragments without nuclei, compatible with aspects of apoptotic bodies.

Actins↗