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Biomedical subjects

L M Levy

Publications and source records attributed to L M Levy.

At least 19 recordsLinked to original sources
PubMed1992

Advances in lymphoma treatment.

There have been considerable advances in the management of patients with lymphoma over the past three decades. In Hodgkin's disease, there was a major break-through in the late 1960s with the development of the MOPP combination regimen. Using this and other more recent combinations, remission rates of up to 80 pc may be achieved overall with many patients having durable remissions. In non-Hodgkin's lymphoma there have been few advances in therapy of the indolent low-grade varieties which remain largely incurable. In the aggressive high-grade lymphomas, some subtypes have proved highly responsive to intensive cytotoxic programmes, giving remission rates and relapse-free survival rates of 70-80 pc. Certain categories, however, such as lymphoblastic lymphoma, remain a problem. Bone marrow transplantation and biological response modifiers have been important recent developments. The search for treatment strategies that improve survival and have relatively low toxicity is a continuing challenge.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Zimbabwe National Cancer Registry: summary data 1986-1989. National Cancer Registry Advisory Committee.

The Zimbabwe National Cancer Registry began operation in 1986. Between 1986-1989, a total of 8 276 cases were identified. Among men of African descent, oesophageal (11.2 pc) and liver cancer (11.0 pc) were most common. Cervical cancer was by far the most common among women of African descent (34.5 pc). Among both males and females of non-African descent, skin cancers (other than melanoma) accounted for one-third of cancers followed by prostate cancer (7.7 pc) in males and breast cancer (18.5 pc) in females. These findings are comparable to earlier reports of the epidemiology of cancer in Zimbabwe.

Causality↗
PubMed1990

MR phase imaging and cerebrospinal fluid flow in the head and spine.

Motion of the cerebrospinal fluid (CSF) in and around the brain and spinal cord was examined in healthy subjects and in a number of patients with abnormalities of the CSF circulation. The pulsatile motion of the CSF was determined by spin echo phase (velocity) imaging, sometimes in combination with gradient echo phase contrast cine. Differences in flow patterns across CSF spaces were observed: flow reversal in the cerebellomedullary cistern and lumbar area relative to cervical CSF, and in the posterior versus the anterior subarachnoid space in the spinal canal. Flow communication was demonstrated in known communicating cysts or cavities. Differences in flow were also noted across spinal narrowing or block, and across the walls of a variety of cystic lesions in the brain and spinal cord. MR phase imaging of CSF flow provides pathophysiological information of potential clinical importance for the assessment of diseases affecting the CSF circulation.

Brain↗
PubMed1989

Stereospecificity of C4 nicotinamide hydrogen transfer of the NADP-dependent glyceraldehyde-3-phosphate dehydrogenase.

The stereospecificity of the reaction catalysed by the spinach chloroplast enzyme NADP-dependent glyceraldehyde-3-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate: NADP+ oxidoreductase (phosphorylating), EC 1.2.1.13) with respect to the C4 nicotinamide hydrogen transfer was investigated. NADPH deuterated at the C4 HA position was synthesized using aldehyde dehydrogenase. 1H-NMR spectroscopy was used to examine the NADP+ product of the GPDH reaction for the presence or absence of the C4 deuterium atom. Chloroplast NADP-dependent glyceraldehyde-3-phosphate dehydrogenase retains the deuterium at the C4 HA position (removing the hydrogen atom), and is therefore a B (pro-S) specific dehydrogenase.

Chloroplasts↗
PubMed1988

Interaction of NADPH and triazine dyes with ferredoxin-NADP+ oxidoreductase.

The ability of NADPH to compete for binding with other ligands of known affinity has been used to provide values for the Kd of NADPH with ferredoxin-NADP+ oxidoreductase (EC 1.18.1.2) (FNR). When the competing ligand is procion red, which binds with a red-shift in spectrum, or Woodwards reagent K(N-ethyl-5-phenylisoxazolium 3'-sulfonate), which covalently modifies an active site carboxyl residue, the calculated Kd for the NADPH-FNR complex is greater than 8 or 0.08 mM, respectively. Because of the feeble (or non-existent) ability of NADPH to dislodge procion red, we propose that this dye and NADPH are not binding at the same site. Procion red must, however, bind additionally at the active site (presumably without spectral perturbation) as it is a competitive inhibitor of NADPH in ferricyanide reduction assays and more crucially proves to be a novel substrate itself, being reduced to a leuco form which can be reoxidised by oxygen. Although a Kd for the NADPH-FNR complex of 0.08 mM is reasonable, we point out the difficulty of interpreting this value and question its physiological significance.

Ferredoxin-NADP Reductase↗
PubMed1988

Hodgkin's disease in black Zimbabweans. A study of epidemiologic, histologic, and clinical features.

A 3-year prospective study of the histologic and clinical features of patients with Hodgkin's disease presenting to the medical units in Harare, Zimbabwe, was undertaken. The histologic pattern of disease was similar to that of other African countries with mixed cellularity and lymphocyte depleted patterns prevailing (58% and 21%, respectively). Unlike most African countries, however, disease occurred most commonly in teenagers and young adults. Nutritional status was poor in just under 50% of the patients. Clinically, the extent of disease at presentation was striking, with over 90% of patients having advanced stage disease in spite of the stated duration of symptoms being moderate. The histologic and clinical findings resembled those reported from other African countries, but in certain aspects the epidemiologic pattern was intermediate between those of affluent and underprivileged communities.

Adolescent↗
PubMed1988

Spinal cord artifacts from truncation errors during MR imaging.

The significance of linear regions of altered signal intensity that appear in sagittal magnetic resonance (MR) images along the length of the spinal cord was investigated. Examinations were performed on ten healthy volunteers and one patient with spinal cord edema. A 0.5-T or a 1.5-T MR system was used. Sampling-related effects (Gibbs phenomenon) at spinal cord edges and cerebrospinal fluid interfaces can lead to different signal patterns within the spinal cord and canal. These artifacts cause problems in interpretation, especially with the use of small object-to-pixel size ratios, by obscuring anatomy and simulating pathologic conditions such as pseudosyringes. Analysis of these intensity variations and of their dependence on sampling may improve the clinical accuracy of MR imaging.

Humans↗
PubMed1988

Fixed spinal cord: diagnosis with MR imaging.

Pulsatile motion of the spinal cord was examined with phase imaging techniques. Sagittal images of the spinal cord were obtained at different times of the cardiac cycle in healthy volunteers, as well as in patients in whom the spinal cord either was tethered, was compressed, or contained an intramedullary lesion. Pulsatile velocity changes of the spinal cord, observed on the phase images, were most marked at the cervical-upper thoracic level. Cord motion was found to be significantly decreased in cases in which the cord was either tethered or compressed. Cord enlargement due to an intramedullary lesion generally did not lead to decreased cord motion. Imaging of pulsatile cord motion may be clinically useful in evaluating diseases restricting cord motion or changing the status of parenchymal compliance.

Adult↗
PubMed1988

Low-grade non-Hodgkin's lymphoma in Zimbabwe: clinical features and stage.

Fifteen patients with low-grade non-Hodgkin's lymphoma were seen in Harare over a 3-year period, and this group constituted approximately 17% of all non-Hodgkin's lymphoma. All but one were of type A (Working Formulation), i.e. small lymphocytic. This low proportion of lesser grades of malignancy and virtual absence of follicular histology was similar to findings in other parts of Africa. The clinical features, however, resembled those reported worldwide with the sex ratio equal, older patients affected, and most patients (87%) having advanced stage disease, often with extranodal spread.

Humans↗
PubMed1988

The pattern of haematological and lymphoreticular malignancy in Zimbabwe.

A 3-year prospective study undertaken in Harare, Zimbabwe, revealed that the relative frequencies of lymphoreticular and haematological malignancies were similar to those of Western countries, and fitted well into the African pattern except that Hodgkin's disease was relatively less and myeloma relatively more frequent. The distribution of non-Hodgkin's and Hodgkin's lymphoma in Zimbabwe corresponds well with the overall trend in Africa, i.e. with the proportion of Hodgkin's disease increasing and that of non-Hodgkin's disease (particularly Burkitt's lymphoma) decreasing on moving away from the equator. The age incidence pattern for Hodgkin's disease was bimodal with the largest peak in adolescence and early adulthood. Disease in very young children was uncommon. In non-Hodgkin's lymphoma the picture was similar to elsewhere in Africa, except that Burkitt's lymphoma was uncommon.

Adolescent↗
PubMed1987

111Indium-tropolone labeled human PMNs: a rapid method of preparation and evaluation of labeling parameters.

Pure polymorphonuclear leukocytes (PMNs) have been isolated from a small amount of human blood by a single-step density gradient centrifugation method using a commercially available Ficoll-Hypaque mixture of density 1.114. The cells were labelled with [111In]tropolone in both buffer and plasma. Cell viability, ability to generate superoxide anion, and chemotaxis were found to be unaltered both before and after labeling. The optimum tropolone concentration for labeling was found to be 1 X 10(-4) M. Labeling efficiency was higher at 37 degrees C than at room temperature. Compared to [111In]oxine, tropolone preparation both in buffer and plasma resulted in consistently higher yields. Preliminary experiments of in vivo cell viability of the labeled PMNs were carried out in rabbits. The ability of the cells to localize in experimentally produced inflammatory lesions was found to be intact. The method of cell separation and labeling described has been found to be simple and rapid and could easily be incorporated in routine nuclear medicine laboratory practice.

Animals↗
PubMed1987

Use of a gamma camera to estimate bone mineral content based on the dual-photon technique.

Bone mineral content evaluations using a point source of 153Gd of strength 100 mCi or less and a Siemens large field of view gamma camera equipped with a converging collimator is reported. Both 44 and 100 ke V images are digitised in 128 x 128 matrices and processed in a Siemens MicroDelta System attached to a VAX 11-750 computer. Shorter imaging time, low source strength and the usage of existing nuclear medicine equipment are the major highlights of the technique. The effective focal distance (EFD) of the collimator used is experimentally determined with a 57Co source and found to be 75 cm. Focal distances are also calculated from measured values of magnification factors at different points on the collimator face to assess the degree of misalignment of converging holes. Due to the high count rate of the system, corrections for dead time losses and image shrinkages are applied. Two additional low-activity point sources of 153Gd, which serve as live time meters of the system, are used for this purpose. In addition, due to the non-homogeneity of the converging collimator, uniformity corrections for each field of view are found to be essential. In external standards made of various amounts of hydroxyapatite, a correlation coefficient greater than 0.990 with a standard error of the estimate (SEE) 0.0225 is obtained between measured and actual values. In a limited clinical trial, high-resolution images of human spines are acquired and quantitative estimates of bone mineral content are evaluated.

Bone and Bones↗
PubMed1986

Morphologic and functional changes in the kidney after percutaneous nephrosto-lithotomy.

Morphology and function of the kidney were studied before and after percutaneous stone extraction in 33 patients with unilateral calculus disease to assess damage secondary to the extraction procedures. Anatomic changes were studied using excretory urography before the procedure and at 3 to 6 months postoperatively, and using nephrostograms and noncontrast nephrotomograms several days after the procedure. Renal function was evaluated with radionuclide renography both before surgery and at either 4 to 6 weeks or about 1 year postoperatively. Six patients had early changes detected clinically and with nephrostograms, but only three of these had abnormalities on delayed excretory urography. Significant changes in renal function were found only in those patients who had clinically detectable complications (p less than 0.05), in one case before symptoms were manifest.

Adult↗
PubMed1985

The Community Alcohol Use Scale: a scale for use in prevention programs.

The Community Alcohol Use Scale (CAUS) was developed as a continuous, reliable, valid, and acceptable measure for primary prevention studies. Items were written following a comprehensive review of the literature on alcohol dependence and alcoholism. Based upon the responses of 315 respondents to the 100-item initial version of the scale, the 45-item CAUS was developed. The CAUS was then cross-validated on a local sample (n = 274) and a provincial sample (n = 745). Estimates of internal consistency were .91, .96, and .94, respectively, for the initial and cross-validation samples. Correlations of .48 and .69 were obtained between the CAUS and the Michigan Alcohol Screening Test for the initial and local cross-validation samples. In the provincial cross-validation sample a correlation of .62 was obtained between the CAUS and the Usual Weekly Alcohol Index. Preliminary cutting scores were developed to identify those at risk for alcoholism, and alcoholics. The CAUS has potential use as an evaluative and predictive instrument in a variety of primary prevention programs.

Adult↗