Search PubMed⌕ Search

Biomedical subjects

G Levin

Publications and source records attributed to G Levin.

At least 73 records · Page 4Linked to original sources
PubMed1975

An index of responsiveness to patient needs: the synchrony ratio (PSI).

Indicators of the effectiveness of mental hospitals currently in use have severe limitations. Admissions, discharges, and occupancy rates are affected by multiple factors and determined largely be institutional policies. A rapidly calculable measure of responsiveness to patient requests for hospital admission is described. The synchrony ratio (psi) requires only that the number of emergency room visits and admissions by known accurately. If hospitals override patient needs, this is reflected in declining psi values. The utility of the synchrony ratio has been tested in a comparison of a general hospital psychiatric service and community mental health center inpatient wards.

Emergency Service, Hospital↗
PubMed1974

Effect of polyoxin D on chitin synthesis and septum formation in Saccharomyces cerevisiae.

The normal sequence of cell separation in Saccharomyces cerevisiae begins with the formation of a primary septum, presumably consisting of chitin, on which secondary septa are later deposited. In the presence of the antibiotic polyoxin D, a potent inhibitor of chitin synthetase, pairs of abnormal cells of two different types were observed by phase-contrast microscopy: the "exploded pair," consisting of two lysed cells from which the cytoplasm had been extruded at the cell junction, and the "refringent pair," consisting of two highly refractile cells joined by a thin bridge. Thus, in both cases the septal region appears to be affected. Observations with the electron microscope showed that the primary chitin septum was not formed in either of these cell types, and as a consequence secondary septa of varying thicknesses were laid down in an abnormal pattern. With [(3)H]glucose as carbon source the incorporation of tritium into the chitin of abnormal cells was inhibited about 90%, whereas the labeling of mannan was normal and that of glucan somewhat reduced. The effective concentrations of polyoxin D (0.1 to 1 mg/ml) were much greater than those required to inhibit chitin synthesis in vitro. Dimethylsulfoxide and amphotericin B, both known to increase cell permeability, enhanced the action of the antibiotic.

Anti-Bacterial Agents↗
PubMed1970

Gamma-ray-induced spore germination of Dictyostelium discoideum.

(60)Co gamma rays can induce germination of the spores of the cellular slime mold, Dictyostelium discoideum, in the absence of heat shock, amino acids, or bacteria food source. About 65% amoebae emergence occurs by 13 hr after a dose of 180 krad.

Cobalt Isotopes↗
PubMedDate not supplied

[Value of a LHRH agonist (Zoladex) in hormonotherapy of advanced cancers of the prostate. Apropos of 22 patients].

Twenty-two patients with metastatic cancer of the prostate were treated with ZoladexR, an LHRH analogue. In all cases plasma testosterone levels decreased to post-surgical castration values. This inhibitory effect of Zoladex on testicular steroid production had a favourable influence on the course of the malignancy, since 75 p. 100 of objective responses were obtained after 3 months of treatment. The functional symptoms were distinctly improved, and the drug was well tolerated, notably by the cardiovascular system. This immediate effectiveness seemed to last for several months, one-half of the patients still being in remission after 3 to 15 months. The beneficial effects of LHRH agonists, similar to those of pulpectomy or oestrogen therapy, are limited by the susceptibility of the tumour to hormones. In view of their effectiveness and good tolerance, LHRH agonists are useful in the management of advanced prostatic cancer, either as initial therapy or to replace a poorly tolerated oestrogen therapy. Further studies are needed to clarify their indications and the possible value of their association with anti-androgens or antimitotic drugs.

Aged↗
PubMedDate not supplied

Poly(amino acid)-b-poly(N,N-diethylacrylamide)-b-poly(amino acid) conjugates of well-defined structure.

Carboxy-terminated oligomers of N,N-diethylacrylamide (DEAAm) with low polydispersity were synthesized by group-transfer polymerization. The oligomers were conjugated with the N terminus of epsilon-N-CBZ-protected poly(lysine) and s-CBZ-protected poly(L-cysteine). The resulting conjugates precipitated in a narrow region of lower critical solution temperatures (LCST) around 29 degrees C. The LCST of poly(lysine)-polyDEAAm-poly(lysine) conjugates was pH-independent and independent of the lengths of poly(lysine) segments. Water-soluble nonstoichiometric conjugate-DNA complexes precipitated above the conjugate's LCST. Covalent complexes of human albumin and poly(cysteine)-polyDEAAm-poly(cysteine) conjugates showed temperature-sensitive behaviour in aqueous solutions.

Acrylamides↗
PubMedDate not supplied

Atenolol improves ventricular function without changing plasma noradrenaline but decreasing plasma atrial natriuretic factor in chronic heart failure.

1 There is good evidence that beta-blockers improve ventricular function, disease progression and survival in patients with left ventricular systolic dysfunction. The aim of this study was to determine the effects of atenolol therapy on the sympathetic nervous system at rest and after ergometric exercise, on left ventricular function and on baseline plasma atrial natriuretic factor (ANF) in ambulatory patients with chronic heart failure (CHF). 2 Twenty-two patients [left ventricular ejection fraction (LVEF) <36%; New York Heart Association II-III] were studied before atenolol treatment. Because of cardiac events (new Hospital admission or death) only 13 patients completed 1 year of treatment. Baseline noradrenaline (NE) concentrations were similar in patients and controls while ANF was higher in patients than in controls (328 +/- 35 pg ml(-1) vs. 37 +/- 3 pg ml(-1); P<0.01). 3 Patients with events showed higher NE (540 +/- 87 pg ml(-1) vs. 303 +/- 44 pg ml(-1); P<0.01) and ANF (460 +/- 70 pg ml(-1) vs. 291 +/- 44 pg ml(-1); P<0.03) at rest; and greater NE response to exercise (2.003 +/- 525 pg ml(-1) vs. 694 +/- 121 pg ml(-1); P<0.005). Atenolol treatment improved LVEF (19.5 +/- 1.9% vs. 33 +/- 3.9%; P<0.001), increased exercise tolerance (9 +/- 3.2 min vs. 17 +/- 4.8 min; P<0.001) and decreased plasma ANF (292 +/- 42 pg ml(-1) vs. 133 +/- 35 pg ml(-1); P<0.01). 4 Reduced basal dihydroxyphenylglycol (DHPG)/NE ratio (3.4 +/- 0.46 vs. 4.3 +/- 0.35; P<0.01) was observed in patients compared with healthy volunteers. Atenolol increased DHPG plasma levels (1.398 +/- 129 pg ml(-1) vs. 913 +/- 86 pg ml(-1); P<0.005) but the DHPG/NE ratio during exercise was not modified after treatment, suggesting that re-uptake of released NE is not changed by beta-blocker treatment. 5 In conclusion, the fact that atenolol treatment improves ventricular dysfunction and clinical status without changing plasma NE levels in CHF patients, suggests that plasma NE is a poor surrogate measurement for cardiac sympathetic activity in this pathology. In addition, decrease in plasma ANF produced by atenolol treatment may reflect the improvement of ventricular function.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Indomethacin inhibits the accumulation of tumor cells in mouse lungs and subsequent growth of lung metastases.

BACKGROUND: The interaction of cancer cells with blood cells and cell wall components evokes inflammatory responses and is a critical event in the metastatic process. Indomethacin is a potent inhibitor of the cyclooxygenase (COX) enzymes and has previously been shown to decrease the growth of primary tumors in vivo. Proinflammatory prostaglandins produced by the two COX enzymes may also play a role in the development of metastases. METHODS: To directly address this question, we tested the effect of indomethacin on the accumulation of circulating [(3)H]-uridine-labeled tumor cells in the lungs and on the subsequent development of lung tumors. RESULTS: We found that inhibition of COX activity in the recipient mice prior to the injection of tumor cells decreased the percentage of the cells arrested in the lungs. This effect was highly significant since it subsequently led to substantial attenuation of lung metastasis development. CONCLUSION: These data thus demonstrate the antimetastatic effect of indomethacin through a mechanism which involves a reduction in tumor cell uptake by the lungs.

Animals↗
PubMedDate not supplied

[Photochemiluminescent study of the antioxidant activity in biological systems. Mathematical modeling].

The mathematical modeling of the kinetics of riboflavin photo-chemiluminescence (PCL) in the presence of antioxidants, superoxide dismutase and ascorbic acid, has been performed. A specially developed computer program "Kinetic Analyzer" was used for the modeling. The PCL intensity of was taken as directly proportional to the superoxide concentration, because lucigenin had been added to the system. It was found, that the experimental curves of PCL virtually coincide with those calculated in the case of the following set of reactions (reaction rate constants, M-1.s-1 are given in brackets): hv + RH-->R. + .O2- (2,3 x 10(-4) s-1); RH + .O2(-)-->R. + H2O2 (1000); RH-->...(0,005 s-1); .O2- + .O2(-)-->... + phi OTOH (2 x 10(5) M-1 s-1); SOD + .O2(-)-->SOD H2O2 (1 x 10(8)); ASC + .O2(-)-->...(2 x 10(7)). Here RH is, .O2(-)--superoxide, R.--riboflavin radical, SOD--superoxide dismutase, ASC--ascorbate.

Ascorbic Acid↗