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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↗
PubMed1990

Detection of interleukin-3 in the serum of mice infected with Mycobacterium lepraemurium.

Infection of mice by Mycobacterium lepraemurium is accompanied by ablation of erythropoiesis in the bone marrow and gross enlargement of the spleen. This, together with increased monocytopoiesis and the earlier demonstration of macrophage colony-stimulating factor in the serum of infected mice, suggested the activity of additional cytokines. Eight weeks after infection of mice by M. lepraemurium, interleukin-3 (IL-3) activity was demonstrated in the serum (titer, 1:3200). The serum titer of IL-3 activity was maximal after 13 weeks (greater than 1:6400) and was slightly reduced after 18 weeks (1:6400). That the IL-3 activity detected in the serum of the M. lepraemurium-infected mice reflected the presence of IL-3 itself was confirmed by a neutralization assay using anti-murine IL-3 antibodies; IL-3 activity in the serum of mice 13 weeks after infection was completely abolished by the anti-IL-3 antibodies. Finally, a 1-kb signal of IL-3 RNA was detected in the spleens of M. lepraemurium-infected mice 13 weeks after infection.

Animals↗
PubMed1990

Pain control in a patient with myeloma in Zimbabwe.

The treatment of pain control in hospitals in developing countries must take into account the knowledge of the local health care workers, the traditional means of curing illness and treating pain, limited resources, and the general cultural values of that society. The authors discuss the treatment history of a patient with myeloma in a hospital in Harare, the capital of Zimbabwe. Although the patient understood and promised to comply with a long-term treatment plan of radio- and chemotherapy aimed at alleviating pain, for periods of time he defaulted and returned home to be treated by traditional healers. In this way, ancestral spirits were appeased. Traditional treatment by scarification did alleviate pain. Although the hospital does not accept such alternative methods of pain control, patients are allowed to leave the hospital to receive native treatment after completing initial courses of therapy and receiving the date of the next treatment course. The authors also discuss the difficulties of giving medication for pain control in Zimbabwe: Health care workers may have misconceptions about addiction, and patient may be too stoical.

Adult↗
PubMed1990

Measurement of cytosolic calcium using 19F NMR.

Fluorine-19 nuclear magnetic resonance (NMR) studies of cells and perfused organs loaded with fluorinated ion chelators represent a new approach to determining cytosolic free calcium levels in situ. The molecular basis for this approach and the relative advantages and disadvantages of the NMR technique are discussed in this paper. Results obtained on perfused normoxic and ischemic rat hearts are presented, indicating that ischemia is associated with an elevation in the level of cytosolic free calcium before the onset of irreversible cell injury. The results are therefore consistent with this elevation playing a causative role in the mediation of myocardial cell injury resulting from ischemia.

Animals↗
PubMed1990

The disease of CBA and BALB/c mice that follows inoculation of a small number of Mycobacterium lepraemurium into the hind foot pad.

To learn if the lack of an immune response in mice infected with Mycobacterium lepraemurium (MLM) was a consequence of the organisms, we studied the disease that followed inoculation of less than or equal to 5000 organisms into the hind foot pads of CBA and BALB/c mice. The mice of both strains demonstrated a rapid increase of bacterial numbers soon after inoculation, with a slowing of the rate of multiplication once the number of organisms per foot pad passed 3 x 10(7). By 1 year after inoculation, the numbers of organisms had reached levels greater than or equal to 10(11) in the spleen and liver, and greater than or equal to 10(8) in the femoral bone marrow. In mice that had been inoculated with as few as 5 MLM or 50 MLM, the organisms had multiplied to numbers greater than 10(8) in the foot pads and to greater than or equal to 10(9) in the spleens, suggesting that the ID50 of viable MLM may be less than or equal to 5 organisms per foot pad. No protection against superinfection could be demonstrated. On the other hand, initial multiplication of MLM in the foot pads was followed virtually immediately by the death of at least 97% of the organisms.

Animals↗
PubMed1989

Doubling time of Mycobacterium lepraemurium in mouse footpads.

The doubling time of Mycobacterium lepraemurium (MLM) was measured in CBA/Ca mice. In eight experiments, 5 X 10(3) MLM were inoculated into the hind footpads of groups of mice, and the organisms were harvested from 1-45 days later. The harvested organisms were enumerated, and the doubling time was calculated assuming that MLM had multiplied without a lag phase and that multiplication continued at a constant rate from inoculation to harvest. Simultaneously, the proportions of viable organisms in the inocula were determined by inoculation of serially diluted suspensions into the footpads of other mice, harvesting 4 months later and calculating the most probable number. MLM were observed to multiply rapidly during the first several days, and more slowly thereafter; the mean initial doubling time was determined to be 0.5 days, a value much smaller than those previously reported by other workers.

Animals↗
PubMed1989

Effects of beta-adrenergic activity on T-wave amplitude.

This study addresses the hypothesis that electrocardiographic T-wave amplitude is influenced by beta-adrenergic stimulation of the heart. Beta-adrenergic activity was manipulated both pharmacologically and through behavioral challenge. Under resting conditions, 12 healthy men underwent infusion of placebo and then the beta-agonist, isoproterenol, and the beta-blocker, propranolol, in a counterbalanced, crossover design. During infusion of placebo, subjects also underwent two behavioral challenges, a structured interview and mental arithmetic. Analysis of the resting data indicated that propranolol produced a significant increase in T-wave amplitude, and isoproterenol produced significant T-wave amplitude attenuation. As previously reported, drug effects were also in evidence for heart rate. Behaviorally-induced reduction of T-wave amplitude was observed for mental arithmetic but not structured interview, which again paralleled heart rate data. Both pharmacological and behavioral data reported in this study support the hypothesis that the T-wave is significantly affected by beta-sympathetic influence on the heart. However, a nonspecific effect of heart rate change on T-wave amplitude would also account for these results. The findings are discussed in terms of their implications for the utility of T-wave amplitude in psychophysiological research.

Adult↗
PubMed1989

Affective responses to activities: a comparative study.

The purpose of this study was to document variation in affective responses to different types of traditional occupational therapy activities. Each of 45 subjects (24 psychiatric inpatients and 21 matched control subjects) participated in a series of four activities: leather lacing, working with clay, filing, and exercycling. Immediately following each activity, each subject completed the Affective Self-Report Checklist designed to elicit affective responses. In addition, each of the activity sessions was professionally videotaped and later rated for affective responses by trained observers. The data analysis revealed no significant differences in affective responses to activities between groups. However, with the groups combined, significant differences were found in affective responses on 6 of the 15 scales of the checklist, with clay and filing the pair of activities that differed most. These findings are a necessary first step in the collection of baseline data regarding responses to activities.

Adult↗
PubMed1989

The COSHH regs.....

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Environmental Exposure↗