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Biomedical subjects

R Levy

Publications and source records attributed to R Levy.

At least 703 records · Page 39Linked to original sources
PubMed1982

CT scanning in senile dementia. A follow-up of survivors.

Survivors from a group of 40 carefully evaluated subjects with senile dementia who had been scanned over two years previously were followed-up, re-scanned and given simple cognitive tests. Of the 12 survivors, 10 agreed to participate. These fell into two sub-groups: one who showed further deterioration in cognitive function and one who did not. The first sub-group showed an increase in ventricle-brain ratio while the second did not. Although the numbers were too small for clear statistical differences to emerge, there was a tendency for affective admixture to be a favourable prognostic indicator and low radiological attenuation density particularly in the right parietal region to be an unfavourable one.

Aged↗
PubMed1982

Biosynthesis and processing of a human T lymphocyte antigen.

The biosynthesis and processing of Leu-1, a human T lymphocyte antigen, has been studied with the use of a monoclonal antibody. This molecule exists on the cell surface as a 67,000 m.w. glycoprotein. Through a series of pulse-labeling studies, in conjunction with the use of the antibiotic tunicamycin and the enzyme Endo-H, the details of glycosylation, processing, and deposition at the cell membrane were examined. The protein backbone of the molecule is 58,000 m.w. High-mannose sugars are added to asparagine residues during synthesis. Within 20 min, these high mannose sugars are converted to complex type carbohydrates, including fucose. The fully processed glycoprotein appears at the cell surface within 30 min after synthesis. This sequence of events is similar to that for other cell surface glycoproteins, including HLA and vesicular stomatitus virus glycoprotein.

Acetylglucosaminidase↗
PubMed1982

The human HLA-DR antigens are encoded by multiple beta-chain loci.

Monoclonal antibodies have been used to isolate and characterize human HLA-DR antigens from human B cell lines. Using sequential immunodepletion experiments, several subsets of DR antigens have been identified. Partial amino-terminal amino acid sequencing has identified these subsets as DR molecules with sequences homologous to the murine I-E alloantigens. In addition, sequence data provide evidence for primary structural differences in the DR beta-chains of two of the subsets. These results provide primary structural evidence for the presence of multiple DR beta-chain loci.

Amino Acid Sequence↗
PubMed1982

Cytosine arabinoside with daunorubicin or adriamycin for therapy of acute myelocytic leukemia: a CALGB study.

A randomized comparison of the relative efficacy and toxicity of daunorubicin (DNR) at 30 or 45 mg/sq m or adriamycin (ADM) at 30 mg/sq m, given on the first 3 days of a 7-day continuous infusion of cytosine arabinoside (ara-C) at 100 mg/sq m/day, shows the outcome to be dependent on anthracycline, dose, and patient age. DNR 45 is significantly better than DNR 30 or ADM 30 for inducing complete remissions (CR) in patients younger than 60 yr, (72%, 59%, 58% CRs, respectively). DNR 30 is better than DNR 45 or ADM 30 for inducing CR in patients older than 60 yr (47%, 31%, 35%, respectively). There was a corresponding shift in the induction mortality for the age, dose, and anthracycline groups. Adriamycin was significantly more toxic to the gastrointestinal tract than daunorubicin. The duration of complete remission, with cyclic courses of maintenance therapy, was independent of the patient's age, the dose, or choice of anthracycline used in induction, and of whether the maintenance courses were given every 4 wk or every 8 wk.

Adolescent↗
PubMed1982

Subtypes of cutaneous T-cell lymphoma defined by expression of leu-1 and Ia.

Monoclonal antibodies were used to characterize immunohistologically the expression of cellular antigens in 25 patients with cutaneous T-cell lymphoma (CTCL). Although all cases expressed the Leu-2a-/Leu-3a+ immunophenotype characteristic of helper T cells, four subtypes were defined based on variable expression of Leu-1 and Ia. In individual patients, the immunophenotype was constant irrespective of body compartment sampled or interim therapy. Ia+ non T-cells typically constituted one-third of the cellular infiltrate. Along with neoplastic cells, Ia+/T6+ dendritic cells were observed within Pautrier microabscesses, dermis, and individually throughout the epidermis. It will be important to determine if different CTCL immunophenotypes represent different biologic subsets of disease or have prognostic relevance. Prospective studies will be facilitated by single- and double-label immunohistologic techniques that allow the simultaneous evaluation of cellular antigen expression and architectural detail.

Adult↗
PubMed1982

Detection of one-millimeter motion under conditions simulating equilibrium blood-pool scinitgraphy.

The widespread clinical applications of multiple-gated equilibrium cardiac blood-pool scintigraphy for qualitative assessment of regional left-ventricular wall motion has raised questions regarding the limits of detectable motion. Under conditions simulating some of the elements of cardiac motion, and using variables associated with multiple-gated equilibrium scintigraphy, we have studied these limits both theoretically and experimentally. The theory of detecting simple edge motion as a function of motion magnitude, system resolution, and counts per pixel is studied both conceptually and by statistical analysis using a line-source activity distribution represented as Gaussian. The experiment involves six independent observers in the qualitative evaluation of the presence and location of edge motion of two cylindrical activity distributions as displayed by a computer.

Computers↗
PubMed1982

Impairment of bromosulfophthalein clearance by bile salt administration in normal volunteers and patients with Dubin-Johnson syndrome.

Sodium dehydrocholate administration significantly impaired bromosulfophthalein (BSP) clearance in six normal volunteers, despite its choleretic effect. In order to determine whether the impairment is at the stage of excretion of BSP from the liver cell into the bile, patients with Dubin-Johnson syndrome were studied. In all six Dubin-Johnson patients, sodium dehydrocholate administration significantly decreased BSP clearance. Since serum bile acid levels are normal in Dubin-Johnson patients, presumably due to a final secretory pathway into the bile distinct from that of BSP and other organic anions, the interaction between BSP and bile acids cannot take place at the stage of excretion into the bile. Based on a previous study and our results, the interaction between BSP and bile salts seems to occur at the site of transport within the liver cell. This mechanism of inhibition may be responsible for the increased serum BSP retention during chemotherapy.

Adult↗
PubMed1982

[Haemoglobin AIc in patients on venesection therapy for haemochromatosis (author's transl)].

Haemoglobin AIc values measured in diabetic patients with idiopathic haemochromatosis tended to be lower than in diabetics without haemochromatosis. The observed difference was analysed with respect to different parameters related to diabetes or haemochromatosis and their treatment (sex, age, duration of diabetes, insulin-dependency, frequency and volume of blood withdrawn) which could possibly explain these low values. Among the twenty-eight subjects with haemochromatosis, thirty-two non-diabetics, twenty-six insulin-dependent diabetics, and twenty-four non-insulin-treated diabetics, we observed that the more frequently venesection therapy was performed, the lower the levels of haemoglobin HbAIc, HbAIa+b tended to be. Thus, the decreased HbAIc rates observed in haemochromatosis patients may be ascribed to the venesection therapy, which induces an increased turnover of red cells, and consequently a decrease of the time available for their glycosylation.

Adult↗
PubMed1981

Response of cutaneous T cell lymphoma to therapy with hybridoma monoclonal antibody.

A murine hybridoma monoclonal anti-T-cell antibody was given to a patient with advanced cutaneous T cell lymphoma. The patient tolerated seventeen treatment courses over ten weeks without symptoms of toxicity. Each treatment caused a reduction in circulating T cells which reached a stable level after two weeks of therapy. Antigenic modulation was observed after each treatment but was fully reversed within three to four days; therefore the treatment was given twice weekly. Monoclonal antibody produced a striking clinical response in skin, lymph nodes, and blood but complete remission was not achieved. Since the remaining disease was antigen positive, failure to eradicate all tumour cells was not a result of immunoselection. At no time did the patient show an antimouse immune response.

Aged↗
PubMed1981

Quantitative computed tomography in senile dementia.

Mean computed tomography (CT) numbers or Hounsfield units (HU) were computed in 15 regions of the brain in routine CT scans of 25 patients with senile dementia and 29 normal community volunteer controls. Mean HU values were significantly lower bilaterally in the medial temporal lobe, anterior frontal lobe, and head of the caudate in the group of patients with senile dementia. There was no correlation between mean HU values and age, and covariate analysis showed that the differences between patients and controls were not attributable to the size of the ventricles. These data suggest that the determination of mean HU values from selected technically suitable regions of CT scans of the brain may have clinical applications of the diagnosis of senile dementia and provide a reliable means of monitoring changes in brain tissue density during the course of senile dementia.

Aged↗
PubMed1981

Studies of a human T lymphocyte antigen recognized by a monoclonal antibody.

A monoclonal antibody (designated L17F12) detects an antigen present on 95-100% of human peripheral T lymphocytes, the majority of thymocytes, and acute lymphocytic leukemia T cells but not B cells, B-cell lines, or monocytes. Examination of frozen tissue sections by the immunoperoxidase method revealed that the cells expressing this antigen were found predominantly in the medulla of thymus and in T-cell zones of lymph node and spleen. The antigen recognized by L17F12 was associated with a cell-surface glycoprotein of 67,000 daltons. L17F12 was used to isolate this molecule from human thymocytes, normal peripheral T cells, leukemic T cells, and T-cell lines. Expression of this antigen on normal T cells was not diminished by prolonged exposure in vitro to various T-cell stimuli. In the absence of complement, L17F12 bound to T cells without altering proliferative functions, thus enabling rapid purification of functionally intact T cells. In the presence of complement, L17F12 was cytolytic for T cells, providing the basis for depletion of T cells from heterogeneous populations. These data suggest that the monoclonal antibody L17F12 recognizes a specific T-cell differentiation protein. This antibody will be useful in studies of the human immune system.

Animals↗
PubMed1981

Ferritin synthesis in inflammation. II. Mechanism of increased ferritin synthesis.

The mechanism of increased ferritin synthesis in inflammation was studied in rat livers 0-48 h after turpentine injection. A subcellular protein synthesizing system was employed in which the respective roles of cell sap factors and polysomes from normal and treated animals could be studied. Two waves of increased ferritin synthesis were found, an early wave with peak activity at 6 h of inflammation, and a second wave starting at about 24 h. The early wave of enhanced ferritin synthesis was associated with increased activity of cell sap factors. In contrast, the late enhancement of ferritin synthesis was characterized by increased polysomal activity as well as increased cell sap activity. These observations suggest a post-transcriptional control mechanism for the early phase of enhanced ferritin synthesis in inflammation, and a transcriptional as well as post-transcriptional control for the late phase of enhanced ferritin synthesis.

Albumins↗
PubMed1981

ECT and cerebral atrophy. A computed tomographic study.

The case-notes of 41 elderly depressives who underwent computed tomography were examined and the ECT history of each patient was assessed. No association was found between ECT and global cortical atrophy or ventricular size, but a significant relationship was demonstrated between frontal lobe atrophy and ECT.

Aged↗