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Biomedical subjects

L Levy

Publications and source records attributed to L Levy.

At least 19 recordsLinked to original sources
PubMed1992

Upper respiratory tract infections and general anaesthesia in children. Peri-operative complications and oxygen saturation.

Conflicting reports regarding the hazards of anaesthesia in children presenting for surgery with an upper respiratory tract infection have appeared in the literature. In the present study 130 children undergoing general anaesthesia with face mask for myringotomy and grommet insertion were graded as having either an acute or recent upper respiratory tract infection or were asymptomatic according to predetermined clinical symptoms and signs. The severity of respiratory and related complications were scored during induction, emergence and recovery. The peripheral oxygen saturation was recorded during induction, emergence, transfer to the recovery ward and in the recovery ward itself. There were no significant differences (p greater than 0.05) in the complication scores between the three groups of children. However, the incidence of hypoxaemia (oxygen saturation less than or equal to 93%) was significantly greater during transfer in the acute infection group (p = 0.001) and the recent infection group (p = 0.02), as well as during recovery in the acute group (p = 0.03) compared with asymptomatic children.

Anesthesia, General↗
PubMed1992

The DM20 protein of myelin: intracellular and surface expression patterns in transfectants.

DM20 is an abundant CNS myelin-specific protein whose role in myelinogenesis is unknown. We have cloned the DM20 cDNA from adult mouse brain total RNA using the polymerase chain reaction and expressed it in HeLa cells. DM20, detected by immunofluorescence in stable transfectants, is present in some cells in large, intensely fluorescent intracellular clumps that probably represent elements of the rough endoplasmic reticulum and Golgi apparatus. Frequently, intense DM20 fluorescence could be detected at the plasma membrane. These findings are consistent with previous studies demonstrating that an intracellular "pool" of DM20 and its larger isoform, proteolipid protein, exists and that a substantial lag occurs between synthesis and insertion of these proteins into the expanding myelin membrane. Permanent DM20 expressors in contact with one another do not display any ultrastructural rearrangements at regions of cell-cell contact, in contrast to what we have previously reported for P0, a PNS-specific protein shown to mediate adhesion of the extracellular faces of the Schwann cell during PNS myelinogenesis. We believe that these results indicate that if DM20 is indeed an adhesion molecule, this property is likely to be significantly more subtle than P0-mediated adhesion.

Amino Acid Sequence↗
PubMed1992

Autocrine and paracrine effects of peptides on human pituitary cells.

In contrast to normal human pituitaries, GH-secreting adenomas cannot process in vivo ProSRIH whereas they do it in vitro. The existence of an endogenous factor able to inhibit ProSRIH processing in vivo was postulated and such a role was analyzed for GHRH. Results showed that when GH adenomas are incubated in vitro with GHRH 10(-8) M, their ProSRIH contents are decreased, percent inhibition being negatively correlated to the amount of endogenously released GHRH. When incubation is performed in the presence of GHRH antibody in order to block the effect of endogenous GHRH, Pro-SRIH content is increased. The same effects are observed on SRIH release: inhibition by GHRH, stimulation by GHRH antibody. Normal rabbit serum had no effect. It may therefore be concluded that the absence of ProSRIH maturation observed in adenomas in vivo may be the consequence of the GHRH release that is known to be higher from GH adenomas than from normal pituitaries.

Adenoma↗
PubMed1992

A three-year prospective study of 137 cases of acute leukaemia in Zimbabwe.

We studied 137 cases of acute leukaemia seen between December 1985 and November 1988, using traditional staining techniques together with cytochemistry and in cases of probable acute lymphoblastic leukaemia (Sudan Black negative) by immunophenotyping. Not all tests were carried out in every case (some cases of ALL could only be classified as T or non-T). Paediatric group (age less than or equal to 14 yrs): 75 cases--acute lymphoblastic leukaemia 52, acute myeloid leukaemia 18, acute undifferentiated leukaemia 5. Peak incidence in 5-9 year group. Male:Female ratio = 1.7:1. acute myeloid leukaemia was associated with chloromas in 2 cases (11 pc). Adult group: 62 cases--acute lymphoblastic leukaemia 23, acute myeloid leukaemia 36 and acute undifferentiated leukaemia 3. Peak incidence in 50-54 age group. Male:Female ratio = 1:1.2. Acute lymphoblastic leukaemia subtypes (all ages) T 16, Common 20, Null 12, 'non-T' 16, B cell 0, untyped 11. 69 pc were of L2 morphology. In T-ALL, 11 had thymomas and Male:Female ratio = 15:1. Male:Female ratio for 'non-T' = 1.5:1. Acute myeloid leukaemia subtypes (all ages) M1 3, M2 8, M3 14, M4 19, M5 8, M6 2, M7 1. Overall incidence of acute leukaemia appears increased at 0.91 per 100,000 per annum from previous studies in Zimbabwe. Common ALL (mean age = 13 years) is an emerging problem and now outnumbers T-ALL (mean age = 10 years). This may be related to a general improvement in living standards and health in Zimbabwe.

Acute Disease↗
PubMed1991

Effects of isoproterenol on T-wave amplitude and heart rate: a dose-response study.

This report examines the hypothesis that electrocardiographic T-wave amplitude is sensitive to graded increases in beta-sympathetic stimulation of the heart. Beta-adrenergic activity was manipulated pharmacologically in 9 healthy men by bolus infusion of isoproterenol in each of six doses: 0.1, 0.25, 0.5, 1.0, 2.0, and 4.0 micrograms. Results indicated that elevations in heart rate above placebo values increased as a linear function of isoproterenol dose. In contrast, the dose-response curve for T-wave amplitude was best described by a quadratic function: an initial reduction in T-wave amplitude at low levels of isoproterenol infusion was followed by a significant reversal of this effect at higher doses. Comparison of the heart rate and T-wave amplitude data points to limitations in the use of the latter as an index of beta-adrenergic activity. One of several possible explanations for the T-wave results would entail a mechanism that preserves ventricular function at high levels of beta-sympathetic stimulation.

Adult↗
PubMed1991

[Presence and characterization of somatostatin precursor in human growth hormone secreting pituitary gland tumor].

Previous studies have demonstrated that normal and tumoral pituitaries release in vitro somatostatin (SRIH) and contain messenger RNAs encoding the preproSRIH. In the present study, we document the presence and characterization of the SRIH precursor in a growth hormone (GH)-secreting human pituitary adenoma, using two biochemical procedures: Sephadex G50 filtration and high performance liquid chromatography (HPLC). Sephadex G50 filtration of a 2M acetic acid extract demonstrated the presence of three SRIH-like immunoreactive (SLI) peaks, distinct from SRIH 1-28 and SRIH 1-14 used as standard. Molecular mass of the SLI material present in each peak was estimated as 21, 17 and 12 kilodaltons (kDa). SRIH 1-28 and/or 1-14 were not detected in this extract. Reverse phase HPLC was performed on a C18 column; all the three forms of SLI material coeluted with the rat hypothalamic proSRIH indicating a high homology between the human pituitary proSRIH and that of the rat hypothalamus. These results demonstrate for the first time the presence of high molecular mass proSRIH forms in a GH-secreting pituitary adenoma, and thus enable us to conclude for a local pituitary production of SRIH.

Chromatography, Gel↗
PubMed1979

A novel fluorinated derivative of diethylstilbestrol.

The synthesis of the diethylstilbestrol (DES) derivative with fluorine atoms present in the positions ortho to the hydroxyl in each ring is described. In vitro studies in a system containing horse radish peroxidase/H2O2 demonstrate extensive oxidation of tetrafluorodiethylstilbestrol to the corresponding dienestrol derivative. Tetrafluorodiethylstilbestrol and DES had comparable in vivo uterotropic activities at a dose of 100 microgram/kg. Competitive binding experiments demonstrated 20-25 fold reduced interaction with the mouse uterine estrogen receptor. This compound may be useful as an experimental estrogen in distinguishing between the biological and toxic effects of DES.

Animals↗
PubMed1979

Dynamic renal scan in the non-visualizing kidney.

Thirty-one patients with 35 non-visualizing kidneys on excretory urography were studied with 99mtechnetium-diethylenetriaminepentaacetic acid scintiscanning. In 11 cases good renal blood flow and concentration were demonstrated on nucleide scanning. All patients had significant parenchyma and recoverable renal function after appropriate surgical management. In 20 cases there was little or no blood flow on the scan. These patients either had a congenitally absent kidney or severely destroyed parenchyma. The 99mtechnetium-diethylenetriaminepentaacetic acid dynamic renal scan is a sensitive method for predicting renal salvageability of a kidney that fails to visualize on excretory urography.

Adolescent↗
PubMed1979

The metabolism of nucleic acids in mice.

The metabolism of three forms of nucleic acid, native-DNA (N-DNA), single strand DNA (SS-DNA), and polyinosinic-polycytidylic acid (poly I : C), was investigated in vivo in randomly bred Swiss-Webster mice. Clearance of these substances from the circulation and tissue localization were determined at selected time intervals following the intravenous injection of 125I-labelled compounds. N- and ss-DNA were removed from the circulation more rapidly than was poly I : C. All three materials localized principally in reticuloendothelial-rich organs, i.e. liver and spleen. N-DNA was degraded by the liver more slowly than was poly I : C or ss-DNA. At 4 h following injection, the liver contained 26%, 13%, and 10% of the injected doses, respectively. Three days after injection, 4.5% of the N-DNA persisted in the liver, as compared to only 0.6% of the poly I : C, and 0.2% of the ss-DNA. The possiblity that these differences in metabolism of N-DNA, poly I: C, and ss-DNA may be related to their differing immunogenic potentials in experimental systems is discussed.

Animals↗
PubMed1978

Effect of pulse dose cyclophosphamide on the anamnestic immune response in NZB/W mice.

Mice exhibiting a spontaneous SLE-like lethal autoimmunity (female NZB/W hybrids) were given monthly doses of cyclophosphamide (CPA) 240 mg/kg p.o. starting at four months of age. Antibodies to DNA and sheep red blood cells (SRBC) were measured as well as general well being of the mice. The CPA-treated group demonstrated a marked increased in survival compared to the untreated controls with reduction of anti-DNA antibody levels but only a slight inhibition of the anamnestic response to SRBC immunization.

Animals↗