Search PubMed⌕ Search

Biomedical subjects

R Levy

Publications and source records attributed to R Levy.

At least 307 records · Page 17Linked to original sources
PubMed1995

Elevated superoxide generation in mononuclear phagocytes by treatment with 1 alpha hydroxyvitamin D3: changes in kinetics and in oxidase cytosolic factor p47.

The effect of 1 alpha-hydroxyvitamin D3 (1 alpha OHD3) treatment on the superoxide production of phagocytic cells in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was studied. A 3-day treatment of CAPD patients with 3 micrograms per day of 1 alpha OHD3 (high-dose treatment) significantly increased NADPH oxidase and killing activities in peritoneal macrophages and peripheral blood monocytes (P < 0.001) as compared with low-dose (0.25 microgram/day of 1 alpha OHD3) treatment or nontreatment. The high oxidase activity observed in macrophages and monocytes after the treatment with 1 alpha OHD3, correlated significantly to the increase in the amount of the cytosolic factor p47 of the NADPH oxidase as detected by western blotting analysis. Superoxide production by the peripheral blood neutrophils of these patients only slightly increased with 1 alpha OHD3 treatment, and the amount of p47 was not affected by 1 alpha OHD3 administration. In order to evaluate the significance of the oxidase cytosolic factor in dictating oxidase activity, a reconstitution of NADPH oxidase was conducted by mixing macrophage cytosols and membranes in a cell-free system. The addition of macrophage cytosol from patients on high-dose treatment to macrophage membranes from patients in all of the categories of treatment resulted in significantly higher (P < 0.001) superoxide production as opposed to the macrophage cytosol from nontreated patients. These results suggest that 1,25(OH)2D3 causes an increase in NADPH oxidase activity in the peritoneal macrophages and monocytes of CAPD patients by inducing synthesis and elevating the amount of the cytosolic factor p47.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcitriol↗
PubMed1995

Cost analysis of in vitro fertilization.

In vitro fertilization (IVF) has become a routine tool in the arsenal of infertility treatments. Assisted reproductive techniques are expensive, as reflected by the current "take home baby" rate of about 15% per cycle, implying the need for repeated attempts until success is achieved. Israel, today is facing a major change in its health care system, including the necessity to define a national package of health care benefits. The issue of infertility and whether its treatment should be part of the "health basket" is in dispute. Therefore an exact cost analysis of IVF is important. Since the cost of an IVF cycle varies dramatically between countries, we sought an exact breakdown of the different components of the costs involved in an IVF cycle and in achieving an IVF child in Israel. The key question is not how much we spend on IVF cycles but what is the cost of a successful outcome, i.e., a healthy child. This study intends to answer this question, and to give the policy makers, at various levels of the health care system, a crucial tool for their decision-making process. The cost analysis includes direct and indirect costs. The direct costs are divided into fixed costs (labor, equipment, maintenance, depreciation, and overhead) and variable costs (laboratory tests, chemicals, disposable supplies, medications, and loss of working days by the couples). The indirect costs are the costs of premature IVF babies, hospitalization of the IVF pregnant women in a high risk unit, and the cost of complications of the procedure. According to our economic analysis, an IVF cycle in Israel costs $2,560, of which fixed costs are about 50%. The cost of a "take home baby" is $19,267, including direct and indirect costs.

Costs and Cost Analysis↗
PubMed1995

Low doses of anandamides inhibit pharmacological effects of delta 9-tetrahydrocannabinol.

It has been shown previously that the endogenous cannabinoid receptor ligand arachidonylethanolamide (anandamide 20:4, n-6) induces in vivo and in vivo effects typical of a cannabinoid partial agonist. We now report that the synthetic docosahexaenylethanolamide (anandamide 22:6, n-3) shows similar activities. In addition we show that these two anandamides, under certain experimental conditions, antagonize the effects of delta 9-THC both in vivo and in vitro. Thus a significant decrease in the potency of delta 9-THC-induced inhibition of adenylate cyclase was observed in N18TG2 neuroblastoma cells that were pretreated with low concentrations of anandamides. At these low concentrations of anandamides had no effect when applied alone. In vivo, Sabra or ICR mice were subjected to a tetrad of tests, designed to detect cannabinoid-induced effects. Mice pretreated (i.p.) with 10 mg/kg of delta 9-THC received injections with anandamides. Only low doses (0.0001-0.1 mg/kg) of the anandamides, which had no effects when administered alone, partially or fully inhibited the THC-induced effects. These findings suggest that the inhibition of delta 9-THC-induced effects by low doses of anandamides may be due to partial agonistic effects of these materials. It is possible that low doses of the anandamides are capable of activating a Gs protein mediated signaling pathway, or may cause an allosteric modulation of the cannabinoid receptor.

Animals↗
PubMed1995

[Changes in the high-amplification electrocardiogram after myocardial revascularization. Comparison between coronary artery bypass and angioplasty].

The signal-averaged electrocardiogram (SA-ECG) was studied in 148 patients undergoing myocardial revascularisation either by coronary bypass surgery (CBS) (64 cases) or transluminal angioplasty (PTCA) (84 cases). The investigation was performed before the procedure, at day 7 (D7) and after 3 months (D120). No difference was observed in the SA-ECG between the two groups before revascularisation. The CBS population was older, more symptomatic and had more severe lesions than the PTCA population. One hundred and thirty-nine patients were followed up until the end of the study protocol (CBS = 63; PTCA = 76). Two criteria of the SA-ECG were significantly modified after CBS: QRS duration (p < 0.05) and Under 40 (p < 0.01). No significant changes were observed after PTCA. In the patients with late potentials (LP) before revascularisation, the mean value of these criteria (Under 40 and Last 40) were significantly modified after CBS (U40 = 54.3 +/- 16 to 35.4 +/- 15; p < 0.01) (L40 = 11.9 +/- 4.7 to 26.1 +/- 24.3; p < 0.01). No changes in these criteria were observed after PTCA. The value of negativation of the criteria of LP for patients with two criteria of positivity was 71.1% after CBS compared with 25% after PTCA (not significant). These observations support the hypothesis of a favourable modification of the arrhythmogenic substrate after myocardial revascularisation, especially by CBS.

Action Potentials↗
PubMed1994

Idiotype-cytokine fusion proteins as cancer vaccines. Relative efficacy of IL-2, IL-4, and granulocyte-macrophage colony-stimulating factor.

Idiotypic determinants, antigenic sites expressed on the variable region of Ig molecules of malignant B cells, represent tumor-specific Ags but are weak immunogens. We have previously shown that the immunogenicity can be dramatically increased by fusing tumor Id to granulocyte macrophage (GM)-CSF. Here, we demonstrate that fusion proteins with IL-2 or IL-4 can also be highly immunogenic. Co-immunization of these fusion proteins with another Id demonstrated the importance of physical linkage between the cytokine and relevant Ag for this enhancement. All three fusion proteins are capable of eliciting significant levels of specific Abs against the Id without the use of carrier proteins or adjuvants, although the GM-CSF fusion protein appeared to be unique in its ability to induce higher titers of anti-Id Abs in the primary response. Furthermore, the Id-IL-2 fusion protein induced high titers of IgG2a and IgG3 anti-Id Abs, whereas the Id-IL-4 and Id-GM-CSF fusion proteins did not. Despite the differences, tumor protection was comparable in all mice having significant titers of anti-Id Abs, regardless of the fusion protein used. We concluded that Id-cytokine fusion proteins are potent immunogens that can elicit significant antitumor immunity. The general approach of fusing a cytokine to a potential Ag may be applicable to the design of vaccines for immunotherapy of other types of tumors as well as for other pathogens and disease states.

Animals↗
PubMed1994

Phase I clinical trial using escalating single-dose infusion of chimeric anti-CD20 monoclonal antibody (IDEC-C2B8) in patients with recurrent B-cell lymphoma.

The B-cell antigen CD20 is expressed on normal B cells and by nearly all B-cell lymphomas. This nonmodulating antigen provides an excellent target for antibody-directed therapies. A chimeric anti-CD20 antibody (IDEC-C2B8), consisting of human IgG1-kappa constant regions and variable regions from the murine monoclonal anti-CD20 antibody IDEC-2B8, has been produced for clinical trials. It lyses CD20+ cells in vitro via complement and antibody-dependent cell-mediated lysis. Preclinical studies have shown that the chimeric antibody selectively depletes B cells in blood and lymph nodes in macaque monkeys. In this phase I clinical trial, 15 patients (3 per dose level) with relapsed low-grade B-cell lymphoma were treated with a single dose (10, 50, 100, 250, or 500 mg/m2) of antibody administered intravenously. Treatment-related symptoms correlated with the number of circulating CD20 cells and grade II events consisted of fever (5 patients); nausea (2), rigor (2), orthostatic hypotension (2), bronchospasm (1), and thrombocytopenia (1). No significant toxicities were observed during the 3 months of follow-up. Serum C3, IgG, and IgM levels, neutrophils, and T cells were largely unchanged. At the three higher dose levels, pharmacokinetics of the free antibody showed a serum half-life of 4.4 days (range, 1.6 to 10.5). Levels greater than 10 micrograms/mL persisted in 6 of 9 patients for more than 14 days. No quantifiable immune responses to the infused antibody have been detected. CD20+ B cells were rapidly and specifically depleted in the peripheral blood at 24 to 72 hours and remained depleted for at least 2 to 3 months in most patients. Two-week postinfusion tumor biopsies showed the chimeric antibody bound to tumor cells and a decrease in the percentage of B cells. Tumor regressions occurred in 6 of 15 patients (2 partial and 4 minor responses). The results of this single-dose trial have been used to design a multiple-dose phase I/II study.

Adult↗
PubMed1994

Is Britain immune?

Explore the source record for details and available documents.

Scientific Misconduct↗
PubMed1994

Monocyte dysfunction in patients with Gaucher disease: evidence for interference of glucocerebroside with superoxide generation.

Gaucher disease patients are occasionally affected by chronic or fulminant infections. Since Gaucher cells originate from tissue phagocytes, we studied the functional implications of glucocerbroside accumulation on phagocytes in Gaucher disease patients. Circulating monocytes and granulocytes from nine type I Gaucher disease patients, and matched controls, were studied. Evaluation of phagocytic activity included (1) maximal superoxide generation rates following stimulation by phorbol 12-myristate 13-acetate (PMA), opsonized zymosan (OZ), or formyl-methionyl-leucylphenylalanine (FMLP); (2) nitroblue tetrazolium reduction test (NBT); (3) chemotaxis toward FMLP; (4) phagocytosis of OZ particles; and (5) killing activity against Staphylococcus aureus. Superoxide generation in monocytes following PMA, OZ, and FMLP stimulation was significantly suppressed at 52% +/- 15%, 39% +/- 8%, and 51% +/- 11% of control, respectively. Superoxide generation in granulocytes was normal. NBT reduction, staphylococcal killing, and phagocytosis were also markedly decreased in monocytes, and normal in granulocytes. Mean chemotaxis rates were normal in both monocytes and granulocytes; however, decreased chemotactic rates were observed in some patients. The abnormality of superoxide generation could be reproduced in a dose- and time-dependent manner in normal circulating monocytes incubated with glucocerebroside. Superoxide generation in glucocerebroside-conditioned normal monocytes in a cell-free system showed normal superoxide generation, reflecting the integrity of the NADPH oxidase complex itself. These results demonstrate markedly compromised phagocytic functions in circulating monocytes in Gaucher disease patients. These abnormalities can be attributed to accumulation of glucocerebroside, since it could be reproduced in normal monocytes incubated with glucocerebroside. Similar abnormalities in Gaucher cells throughout the reticuloendothelial system could impair host defense, and may be of particular importance in the pathogenesis of osteomyelitis in Gaucher disease patients.

Adult↗
PubMed1994

Synthetic peptide ligands of the antigen binding receptor induce programmed cell death in a human B-cell lymphoma.

Peptide ligands for the antigen binding site of the surface immunoglobulin receptor of a human B-cell lymphoma cell line were identified with the use of filamentous phage libraries displaying random 8- and 12-amino acid peptides. Corresponding synthetic peptides bound specifically to the antigen binding site of this immunoglobulin receptor and blocked the binding of an anti-idiotype antibody. The ligands, when conjugated to form dimers or tetramers, induced cell death by apoptosis in vitro with an IC50 between 40 and 200 nM. This effect was associated with specific stimulation of intracellular protein tyrosine phosphorylation.

Amino Acid Sequence↗
PubMed1994

Neocortical cholinergic activities differentiate Lewy body dementia from classical Alzheimer's disease.

Activity of the enzyme which synthesizes acetylcholine, choline acetyltransferase, was estimated in the neocortex of three series of control and demented cases. Clinically demented cases were divided into those with the classical neuropathological features of Alzheimer's disease (numerous neocortical plaques and tangles) and those with Lewy bodies in the brain stem and cortex (together with plaques and variable neurofibrillary pathology). In the Lewy body cases neocortical choline acetyltransferase was consistently lower than in the classical Alzheimer-type cases. Two of the Lewy body cases with extremely low cholinergic activity were responders in therapeutic trials of the cholinesterase inhibitor, tacrine, and the combined data suggest that cholinergic therapy may be particularly relevant to patients with Lewy body type dementia.

Alzheimer Disease↗
PubMed1994

The requirement of p47 phosphorylation for activation of NADPH oxidase by opsonized zymosan in human neutrophils.

Protein kinase C (PKC) inhibitors, staurosporine or 1,5-isoquinolinesulfonyl)-2-methylpiperazine (H7), inhibited NADPH oxidase activity and phosphorylation of 47 kDa protein (p47) in PMA-stimulated neutrophils in a dose-dependent manner. These PKC inhibitors, at the same doses, did not affect oxidase activity and caused only partial inhibition of p47 phosphorylation in OZ-stimulated neutrophils. There was residual (20%) phosphorylated p47 in the membranes of OZ-stimulated cells in the presence of PKC inhibitors, at concentrations which caused total inhibition of oxidase activity and p47 phosphorylation in PMA-stimulated neutrophils. In the presence of ionomycin, which increased intracellular calcium ion concentrations, staurosporine was less effective in inhibiting both superoxide generation and p47 phosphorylation stimulated by PMA, similar to its effect in OZ-stimulated cells. The results indicate that some phosphorylation of p47 always accompanied oxidase activation induced by PMA or OZ, though the degree of phosphorylation of membrane-bound p47 does not directly correlate with rates of superoxide production.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Elevated NADPH-oxidase activity in neutrophils from bile-duct-ligated rats: changes in the kinetic parameters and in the oxidase cytosolic factor p47.

Stimulated superoxide generation was 2-fold higher in neutrophils from 20 rats with common bile-duct ligation (CBDL) compared to that of 20 sham-operated control rats. In order to study the mechanism of the higher NADPH oxidase activity in CBDL rats, the kinetic parameters of NADPH oxidase were analyzed. The Vmax of the NADPH oxidase in CBDL rat neutrophils was significantly higher than that of control rat neutrophils (10.2 and 5.3 nmol/min, respectively). The membrane and cytosol fractions of the oxidase were studied in a cell-free system. Neutrophil cytosol from CBDL rats added to neutrophil membranes from either CBDL or control rats produced 22.4 +/- 1.6 and 21.0 +/- 1.4 nmol/10(6) cells per 10 min, respectively. When neutrophil cytosol from control rats was mixed with neutrophil membranes from control or CBDL rats the generation of superoxide was 10.6 +/- 1.4 and 10.0 +/- 1.5 nmol/10(6) cells per 10 min, respectively. These results suggest that the cytosol components of the oxidase regulate its activity. By immunoblot analysis it was shown that the amount of the cytosolic factor p47 in neutrophils of CBDL rats is higher than that present in an equal number of neutrophils from control rats.

Animals↗
PubMed1994

Lymphoma regression induced by monoclonal anti-idiotypic antibodies correlates with their ability to induce Ig signal transduction and is not prevented by tumor expression of high levels of bcl-2 protein.

Custom-made monoclonal anti-idiotype antibodies (anti-Id MoAbs) have been tested as a treatment modality in 34 non-Hodgkin's lymphoma (NHL) patients. Partial or complete tumor remissions have been induced with this treatment in 68% of these patients. One mechanism by which anti-idiotype antibodies may have induced these tumor responses is via a direct antiproliferative effect on the tumor cells, resulting in apoptosis. Primary NHL cells do not proliferate well enough in vitro to test this hypothesis directly. Therefore, we studied the effect of anti-idiotype antibodies on signal transduction through the surface Ig receptor as measured by the induction of cellular protein tyrosine phosphorylation. To assess whether bcl-2 protein could protect lymphoma cells from death induced by anti-Id MoAb, we also measured the level of bcl-2 protein in the same tumor cells. We found a strong correlation between the ability of an anti-Id MoAb to induce an increase in tyrosine phosphorylation in vitro and its ability to induce a tumor regression in the patient. By contrast, the level of bcl-2 expressed by the tumor cells was not correlated with clinical response to anti-Id MoAb treatment.

Antibodies, Anti-Idiotypic↗
PubMed1994

The requirement for phospholipase A2 for activation of the assembled NADPH oxidase in human neutrophils.

Phospholipase A2 (PLA2) inhibitors suppressed simultaneously, in a dose-dependent manner, the activation of NADPH oxidase and the release of 3H-labelled arachidonic acid ([3H]AA) stimulated by either phorbol 12-myristate 13-acetate (PMA) or opsonized zymosan (OZ) in human neutrophils. In spite of total inhibition of superoxide production in the presence of the PLA2 inhibitors, 10 microM bromophenacyl bromide (BPB) or 20 microM quinacrine, a maximal phosphorylation of p47 and translocation of p47 and p67 to the neutrophil membranes induced by PMA or OZ was observed. Addition of 10 microM free AA, which by itself did not stimulate superoxide generation, restored oxidase activity in neutrophils treated with PLA2 inhibitors. These findings indicate that phosphorylation and translocation of the cytosolic factors to the membranes are not sufficient for generating superoxide; a functional PLA2 is also needed to stimulate the oxidase activity. The inhibition of PLA2 activity did not prevent the phosphorylation of p47, suggesting that the location of PLA2 is downstream of and does not activate protein kinase C.

Acetophenones↗