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Biomedical subjects

E Levi

Publications and source records attributed to E Levi.

At least 55 records · Page 3Linked to original sources
PubMed1991

Malignant fibrous histiocytoma of the vagina and vulva successfully treated by combined chemotherapy and radiotherapy.

Combined vaginal and vulvar malignant fibrous histiocytoma has not been reported previously. Radical vulvectomy with node dissection is the currently recommended therapy for a vulvar lesion of this type. We present a case with complete tumor regression after combined chemotherapy and radiotherapy. The surgical approach in our patient was inappropriate due to advanced disease. Follow-up examinations for 6 years after initiation of therapy showed no evidence of local recurrence or distant metastasis. Chemotherapy followed by radiotherapy should be considered as an alternative to surgery in patients with advanced vaginal and vulvar involvement and in patients in whom complex medical problems preclude extensive surgical procedures.

Aged↗
PubMed1991

Inhibition of angiotensin converting enzyme by ramipril in serum and tissue of man.

Studies in animal models have indicated that ramipril is a potent inhibitor of angiotensin converting enzyme (ACE) in serum and tissue. In our study, the normal range of ACE activity and the inhibitory effect of short-term oral administration of ramipril on ACE activity in human serum and tissue samples of renal cortex, heart and blood vessels were determined. ACE activity in the renal cortex (125.2 +/- 11.5 nmol/mg per min) was greater than 600 times that of the heart (0.20 +/- 0.01 nmol/mg per min), greater than 500 times that of the veins (0.23 +/- 0.09 nmol/mg per min) and greater than 150 times that of the arteries (0.80 +/- 0.23 nmol/mg per min). ACE activity in the renal cortex and arteries 2 h after last dosing was almost completely inhibited by ramipril whereas ACE activity in the veins and heart was inhibited to a lesser extent. Our results demonstrate in man, for the first time, an inhibition of tissue ACE following short-term oral treatment with an ACE inhibitor.

Administration, Oral↗
PubMed1991

Effects of atracurium and pancuronium on the oculocardiac reflex in children.

The authors compare the effect of two muscle relaxants, atracurium and pancuronium, on the bradycardia resulting from the oculocardiac reflex during eye surgery for strabismus in children. Two groups, each composed of 15 children, received either pancuronium or atracurium during strabismus operations. Heart rate and rhythm were observed at several points during the operations, and the changes that occurred in the two groups were compared. We found that the incidence and severity of the bradycardia, the incidence of dysrhythmias, and the need for atropine administration were significantly greater in the atracurium group than in the pancuronium group.

Atracurium↗
PubMed1991

Selective inhibition of duodenal and jejunal villous cell alkaline phosphatase by the duodenal ulcerogen cysteamine.

We have found that cysteamine-HCl, a potent duodenal ulcerogen, after a single subcutaneous injection (30 mg/100 g body weight), inhibited villous cell duodenal and jejunal alkaline phosphatase (APase) under in vivo and under in vitro conditions. The duodenal and jejunal crypt-cell APase was not susceptible to cysteamine inhibition. Ileal APase from both the villous and the crypt cells was unaffected by cysteamine. Tissue-nonspecific APase from the kidney and liver was not affected by cysteamine either. The differences in tissue and cellular accumulation of cysteamine, the submolecular differences in APase molecules, and its anatomical localization in mucosal cells along the small intestine could explain the different degrees of susceptibility to cysteamine inhibition. The extent of duodenal APase inhibition by cysteamine was highly pH-dependent and varied from 5% to 85% within a pH range of 7.5-10.5. A shift in pH optimum from 9.6 to 9.3 was found in the presence of cysteamine. The inhibition of duodenal villous cell APase was greatly dependent on cysteamine concentration (Ki = 2.65 mM). At a fixed concentration of cysteamine it was not influenced by substrate concentration. Cysteamine did not change the Km value for duodenal APase but did decrease its Vmax to 46% and 15% of the controls when added in the assay or injected subcutaneously, respectively, indicating that the inhibition was of the linear, 'noncompetitive' type. Somehow cysteamine increased the requirement in the activation energy for substrate hydrolysis as well. The data indicate that macromolecular transformations could take place in the mucosal cells of duodenum after cysteamine administration.

Alkaline Phosphatase↗
PubMed1990

Candidate ligand for the c-kit transmembrane kinase receptor: KL, a fibroblast derived growth factor stimulates mast cells and erythroid progenitors.

The c-kit proto-oncogene encodes a transmembrane tyrosine kinase receptor for an unidentified ligand and is allelic with the murine white-spotting locus (W). W mutations affect melanogenesis, gametogenesis and hematopoiesis during development and in adult life. Cellular targets of W mutations in hematopoiesis include distinct cell populations in the erythroid and mast cell lineages as well as stem cells. In the absence of interleukin-3 (IL-3) mast cells derived from normal mice but not from W mutant mice can be maintained by co-culture with 3T3 fibroblasts. Based on the defective proliferative response of W mast cells in the 3T3 fibroblast co-culture system it had been proposed that fibroblasts produce the c-kit ligand. We have used a mast cell proliferation assay to purify a 30 kd protein, designated KL, from conditioned medium of Balb/3T3 fibroblasts to apparent homogeneity. KL stimulates the proliferation of normal bone marrow derived mast cells but not mast cells from W mice, although both normal and mutant mast cells respond similarly to IL-3. Connective tissue-type mast cells derived from the peritoneal cavity of normal mice were found to express a high level of c-kit protein on their surface and to proliferate in response to KL. The effect of KL on erythroid progenitor cells was investigated as well. In combination with erythropoietin, KL was found to stimulate early erythroid progenitors (BFU-E) from fetal liver and spleen cells but not from bone marrow cells of adult mice and from fetal liver cells of W/W mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1990

In vitro effects of thyroxine on the mechanical properties of erythrocytes.

In vitro effects of thyroxine on erythrocyte deformability and mechanical fragility were observed. Deformability of erythrocytes was improved in a dose dependent manner by thyroxine. Mechanical hemolysis was found to be lower if thyroxine was included in erythrocyte suspensions at concentrations close to the physiological levels (10(-9)M). These changes might be related to the alterations of intracellular calcium concentration, as in the erythrocyte suspensions containing 10(-9)M thyroxine, intracellular calcium concentration was found to be 30 times lower than the control suspensions which did not contain thyroxine. Thyroxine also reduced the mechanical hemolysis ratio in calcium loaded cells. These observations suggest that thyroxine might play some role in the regulation of the mechanical properties of erythrocytes which might be mediated via the effects on calcium metabolism.

Adult↗
PubMed1990

A novel autoregulatory cytokine is required for the regulation of autoaggressive responses.

Limiting dilution studies indicate that cells with the potential to lyse autologous target cells exist in the peripheral blood of all normal individuals. In contrast to allocytotoxic cells, autocytolytic cells are down-regulated by a second less frequent cell population. When recombinant interleukin 2 is substituted for crude lymphocyte conditioned medium in these limiting dilution experiments, autocytotoxicity develops normally. Under these conditions, however, the autocytotoxic response is not down-regulated. Mixing crude lymphocyte-conditioned medium together with recombinant interleukin 2 restores the regulation of autocytotoxicity normally seen at high responder cell dose. These findings indicate that a second soluble factor present in the conditioned medium is necessary either for the activation, growth, or differentiation of the regulatory cell population or alternatively, to render the cytotoxic population responsive to the activity of regulatory cells. Gel filtration studies indicate that the molecular weight of this factor is between 60 and 80 kd. This factor appears to be distinct from known immunologically active cytokines. It is conceivable that deficiencies of this cytokine may be relevant to the pathogenesis of autoimmune diseases or graft-versus-host reactions.

Biological Factors↗
PubMed1990

Effect of duodenal ulcerogens mepirizole and propionitrile on small intestinal and liver alkaline phosphatase activity in rats.

Duodenal ulcer could be induced in rats by a single subcutaneous injection of the anti-inflammatory agent mepirizole (M) or by the alkyl chemical propionitrile (P). Contrary to M, P provokes HCl hypersecretion as well. We used these animal models of duodenal ulcer to study the preulcerogenic molecular changes in the mucosal cells and their causal relationship to HCl hypersecretion. It was found that M and P induced the dose- and time-dependent decrease of duodenal alkaline phosphatase (DAP) activity. The decrease was detected at 4 h, with a nadir at 12 h after the injection of both drugs. The decrease of alkaline phosphatase activity was organ-specific after P administration and it was even regional-specific along the small intestine after M administration. At the level of mucosal cells of duodenum the effect of the ulcerogens was enzyme-selective. Both ulcerogens decreased protein and alkaline phosphatase activities; however, they had no effect on lysosomal acid phosphatase. Contrary to cysteamine (C), the effect of M and P on DAP depletion could not be reproduced under in vitro conditions. An interference of P and a slight additive effect of C on DAP depletion after simultaneous subcutaneous administration with M to the rats was found. The results indicate that the DAP depletion after in vivo administration of the three duodenal ulcerogens could be provoked by at least two different mechanisms. The decrease of DAP activity seems to be a general property of the duodenal ulcerogens independent of their effects on gastric acid secretion or on the suppression of alkaline secretion in the duodenum. As a late molecular event most probably elicited by the early morphological changes, the decrease of DAP activity could rather be related to ulcer healing than to its pathogenesis.

Alkaline Phosphatase↗
PubMed1990

Immunologic effects of AS101 in the treatment of cancer patients.

AS101 [ammonium trichloro(O,O'-dioxyethylene)tellurate] is a new immunomodulator previously shown to stimulate the production of different cytokines in vitro and in vivo. We report here our results of a phase I clinical trial conducted on 47 cancer patients with advanced malignancies. AS101 was administered intravenously at escalating doses from 1 to 10 mg/m2, twice or thrice a week. The maximal tolerated dose has not yet been determined. However, significant immunologic responses were noted at dose levels of 1-3 mg/m2 administered three times a week. At these doses statistically significant rises in gamma-interferon, natural killer cell activity, tumor necrosis factor and interleukin-2 (IL-2) levels as well as the expression of IL-2 receptors were noted. In most of the immunologic parameters the maximal response was seen at 3 mg/m2. Throughout the study toxicity was minimal. In view of these results phase II studies are currently being initiated.

Adjuvants, Immunologic↗
PubMed1989

A system for on-line detection and resolution of radiolabeled DNA molecules and its application to automated DNA sequence analysis.

We describe a system for the real-time detection of radioactively labeled DNA molecules in gel matrix, and we demonstrate the application of this system to DNA sequence analysis. DNA sequencing reactions prepared by the Sanger chain termination method are resolved by electrophoresis on 8% polyacrylamide gels. During electrophoresis the 32P-labeled DNA fragments are detected by solid state detectors positioned 22 cm from the top surface of the gel. This system is able to resolve a DNA sequence of 300 bases or greater. Optimized protocols that allow sequence information to be obtained from single stranded and double-stranded templates are described. A linear relationship exists between the input dpm and the integrated peak values over a 20-fold range indicating that accurate DNA quantitation is also possible using this system.

Automation↗
PubMed1988

The response of human marrow colony-forming units-granulocyte and macrophage to inhibition by prostaglandin E and acidic isoferritins is associated with expression of MHC class II antigens and requires the participation of a CD8+ T lymphokine.

The in vitro expression of MHC class II Ag by human bone marrow colony-forming unit-granulocyte and macrophage (CFU-GM) and their proliferative response to negative growth regulators in agar culture are transient and can be modulated in vitro by 24-h suspension culture in the presence of PGE. Analysis of the participation of accessory cells in this phenomenon indicates that the ability of PGE to modulate CFU-GM MHC class II expression, the proportion of CFU-GM in S-phase of the cell cycle and the responsiveness of CFU-GM to inhibition in vitro by two negative growth regulators, acidic isoferritin inhibitory activity and PGE itself, requires the participation of CD8+ T lymphocytes. This effect is mediated by a lymphokine of m.w. 27,000 that we have purified to apparent homogeneity. This lymphokine possesses neither colony stimulatory nor inhibitory activity, is produced by both peripheral blood and bone marrow CD8+ T lymphocytes, as well as the CEM T-ALL cell line, and requires the obligatory presence of PGE for activity.

Adult↗
PubMed1988

The influence of cysteamine and propionitrile on duodenal phosphoprotein phosphatase in rats.

Cysteamine and propionitrile cause severe duodenal ulcers with perforation within 24-48 h after a single injection in rats. These animal models were used to gain insight into the early, preulcerogenic biochemical changes in the duodenal mucosa. The results indicate that a single sc injection of cysteamine and propionitrile induced dose- and time-dependent decreases in the activity of phosphoprotein phosphatase (PPPase) in homogenate and particulate fractions of rat duodenal mucosa. The decrease in enzyme activity was detectable 4 h after the injection of the ulcerogens, it was maximal at 12 h, and hardly detectable at 24 h. No effect on the enzyme activity was found under in vitro conditions. PPPase activity in the liver was not influenced by either cysteamine or propionitrile. Furthermore, the toxic but nonulcerogenic derivative of cysteamine ethanolamine had no effect on PPPase in the duodenum. Thus, the effect of the duodenal ulcerogens on PPPase activity was indirect and organ specific, related only to the target organ (i.e., duodenal mucosa). The effect of the drugs was also selective at the level of mucosal cells: both duodenal ulcerogens depleted protein and alkaline phosphatase but not lysosomal acid phosphatase. The decrease of PPPase activity could be a general property of the duodenal ulcerogens since it is independent of their effect on endogenous somatostatin.

Acid Phosphatase↗
PubMed1988

Distinction of partially purified human natural killer cytotoxic factor from recombinant human tumor necrosis factor and recombinant human lymphotoxin.

Natural killer cell cytotoxic factor (NKCF), a cytotoxic factor contributing to human natural killer cell-mediated cytotoxicity, was generated from lymphocyte-conditioned medium using various stimuli. Crude NKCF activity was concentrated, and partially purified by ammonium sulfate precipitation and gel filtration. NKCF activities eluted as two molecular weight peaks, corresponding to Mr 33,000-43,000 (pool I) and approximately Mr 5,000 (pool II). The cytotoxic activity and target specificity of the partially purified NKCFs were found to be different from both recombinant human TNF and recombinant human lymphotoxin. In the NKCF assay, up to 10(6) units/ml of TNF and lymphotoxin had virtually no effect, whereas both NKCFs lysed 22% (range 17-33%) of the NK-sensitive target K562. In contrast, TNF and lymphotoxin were active in a standard assay against the sensitive murine L929 fibroblast cell line in all concentrations tested (10(-1)-10(6) units/ml). In addition, the effect of these cytotoxic factors in a short-term (4-h) chromium-release assay using peripheral blood mononuclear cells as effector cells was tested: only NKCF (pool I), but not TNF, lymphotoxin, or low molecular weight NKCF (pool II), enhanced NK and lymphokine-activated killer cell cytolysis, both against the NK-sensitive target K562 and the NK-resistant melanoma cell line SK-MEL 30. Results were not affected in the presence of neutralizing antibodies against TNF. NKCF could, therefore, be distinguished from TNF and lymphotoxin with respect to their biological activities.

Cell Line↗
PubMed1988

Cobalt-dependent protein phosphatases from human cord blood erythrocytes. I. Submolecular structure and regulation of activity of E3 casein phosphatase.

We have identified three phosphoprotein phosphatases in the cytosol of human cord blood erythrocytes by sequential anion-exchange chromatography and gel filtration. The most abundant was E3 protein phosphatase. After rechromatography on a column of Ultrogel AcA-44 the enzyme had a molecular weight of 95,000 daltons. According to the data obtained by SDS/PAGE, the 95,000-dalton form was composed of non-identical subunits with a molecular mass of 23,000 and 16,000 daltons. Since ethanol decreased the molecular mass of the 95,000-dalton enzyme to 25,000 daltons, we suggest that the protein of 23,000-25,000 daltons represents the catalytic subunit. The decrease in the molecular weight is followed by a 2-fold increase in the Vmax value and by a change in kinetics: the negatively cooperative 95,000-dalton enzyme (h = 0.45) transforms into Michaelis-Menten kinetics (h = 1.0) in the 25,000-dalton form. Both molecular forms, 95,000 and 25,000 daltons, only dephosphorylated casein but not phosvitine and histones. Both forms were activated by CoCl2 and inhibited by organic, and most potently, by inorganic pyrophosphates to approximately the same degree. As opposed to the inorganic pyrophosphate, which affects the catalytic properties of the enzyme molecule, CoCl2 did not affect the catalytic properties of the enzymes, but it probably did affect the rate of 'E-S' complex formation. CoCl2 protected the 95,000-dalton enzyme from pyrophosphate inhibition. The data indicate that CoCl2 and pyrophosphate may take part in the regulation of the activity of both forms of E3 phosphatase.

Chromatography, Gel↗
PubMed1988

Cobalt-dependent protein phosphatases from human cord blood erythrocytes. II. Further characterization of E2 casein phosphatase.

Of three casein phosphatases isolated from the cytosol of human cord blood erythrocytes two were cobalt-dependent, E2 and E3. In the presence of CoCl2, E2 activity was the most prominent. In addition to casein, E2 dephosphorylated phosvitin and p-nitrophenyl phosphate (p-NPP) with pH optima at 6.8-7.2 for proteins and 9.0 for p-NPP. The native enzyme had a molecular weight of 104,000 daltons after AcA-44 Ultrogel filtration. According to SDS/PAGE it consisted of two subunits, 78,000 and 15,000 daltons. The 104,000-dalton form exhibited Michaelis-Menten kinetics and had the greatest affinity for casein between protein substrates tested. Ethanol denaturated the enzyme by 80%. Optimal activation of E2 phosphatase was achieved with 5 mmol/l CoCl2 which did not affect the catalytic properties of the enzyme but did affect the rate of 'E-S' complex formation. Inorganic pyrophosphate was not inhibitory for the 104,000-dalton enzyme. Judging by all these properties the natural substrate for E2 casein phosphatase could be P-pyruvate kinase.

Caseins↗
PubMed1988

Use of a chemically modified T7 DNA polymerase for manual and automated sequencing of supercoiled DNA.

Procedures are presented for reliable and accurate nucleotide sequence analysis using as template supercoiled DNA prepared by a modified rapid boiling minipreparation protocol. This method yields DNA templates suitable for sequencing within 1 h of bacterial harvest. We describe optimal reaction conditions for supercoiled miniprep DNA sequencing using a modified T7 DNA polymerase (Sequenase) in dideoxynucleotide chain termination reactions. We demonstrate that under these conditions, the sequencing data obtained with miniprep DNA is indistinguishable from that obtained with CsCl purified supercoiled DNA or from that obtained using single stranded DNA templates. We further show that the supercoiled DNA sequencing reactions can be analyzed on a commercially available automated DNA sequencing system that detects 32P labeled DNA during its electrophoretic separation. Taken together, these developments represent a significant improvement in the process of nucleotide sequence analysis.

DNA, Superhelical↗