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Biomedical subjects

N Salem

Publications and source records attributed to N Salem.

At least 163 records · Page 9Linked to original sources
PubMed1986

Characterization of an automated apparatus for precise control of inhalation chamber ethanol vapor and blood ethanol concentrations.

Inhalation chambers with a monitoring and control apparatus for ethanol vapor exposure of small animals were constructed. A thermal conductivity detector was employed for continuous measurement of inhalation chamber ethanol vapor concentration. The concentration was maintained within a very narrow range (+/- 1 mg/liter) by incorporating into the design a feedback loop which controls the ethanol pump. As expected, the blood ethanol concentrations (BEC) of male Sprague-Dawley rats were positively and linearly correlated to the chamber ethanol concentration. When rats were exposed for 24 hr to a chamber ethanol concentration of 17, 25, or 32 mg/liter, correspondingly low, moderate, or high mean blood ethanol levels were obtained. When a large population of this strain of rats (n = 121) was exposed to a constant ethanol vapor concentration for 14 days (25 mg/liter) considerable interindividual variation in blood levels occurred. There was also individual variation over time in the BEC of animals monitored. The mean +/- SD BEC was 189 +/- 90 mg/100 ml for this population and a gaussian-like distribution was obtained with regard to BEC. Behavior characteristic of alcohol withdrawal was observed in rats with BEC greater than 120 mg/100 ml after 3.5, 7, or 14 days of exposure. This apparatus and inhalation paradigm make possible the precise control of chamber ethanol concentration which markedly enhances control over both intra- and intersubject fluctuation in blood ethanol levels during alcohol exposure and the comprehensive examination of relationships between a wide range of blood ethanol concentrations and their physiological and biochemical effects.

Air↗
PubMed1985

Malignant mesothelioma of testicular tunica.

A case of malignant mesothelioma of testicular tunica in a 26 year old male is presented. Operation was followed by local radiotherapy. The patient remains disease free one year after initial diagnosis.

Adult↗
PubMed1985

Alteration in the membrane fatty acid composition of human lymphocytes and cultured transformed cells induced by interferon.

The effects of interferon (IFN) treatment on the lipid composition of human peripheral blood lymphocytes or transformed cell line cells were investigated. The major phospholipid classes of lymphocytes as analyzed by 2-dimensional TLC and quantified by phosphorous content were phosphatidylcholine (PC, 43%) and phosphatidylethanolamine (PE, 28%), along with phosphatidylserine (9%) and phosphatidylinositol (8%). The membrane-impermeant reagent, trinitrobenzenesulfonate was used to covalently label cell surface PE. Fatty acid (FA) composition, determined by gas-liquid chromatography, showed a distinct pattern in each lipid class, with a predominance of 16 and 18 carbon fatty acids (FA) in PC and PE respectively. Arachidonic acid (20:4) and, to a lesser extent, docosahexanoic acid (22:6) were predominant in PE. The degree of unsaturation in each class, expressed as the ratio between unsaturated and saturated FA (U/S), was higher in PE (1.72) than in derivatized trinitrophenyl cell surface PE (TNP-PE, 0.57) or PC (0.64). Treatment with IFN resulted in an increased U/S ratio in cell surface PE (1.10) but not in other PE species (1.46). A small increase in unsaturation (0.88) was also observed in PC. Most of the increase in TNP-PE U/S was accounted for by an increase in 20:4 and a concomitant decrease in 18:0. These alterations were observed in the absence of quantitative change in the principal phospholipid classes or in the FA composition of the total lipid extract. In K562, a transformed cell line with characteristics of the erythromyeloid lineage, PE was found to be the most saturated lipid class with a predominance of 18:0. In PC, 16:0 was most abundant. Among unsaturated FA, 18:1 predominated in all lipid classes studied. Treatment with natural IFN alpha for 30 hr generally resulted in a decrease in saturated FA and an increase in unsaturated FA, which was most marked in PE. The U/S ratio in PE was highest in K562 cells during the time of maximal cell proliferation as assessed by tritiated thymidine incorporation. TNP-PE simultaneously decreased. Daudi cells, a B-lymphoblastoid cell line, demonstrated changes in FA composition of lipids with decreased saturated and monoenoic FA after IFN treatment, whereas DIF3 (a clone selected for lack of sensitivity to IFN) showed no change. These studies document changes in membrane FA composition of lymphocytes treated with IFN and correlate IFN-induced changes in transformed cell line FA with effects on proliferation. They further show the existence of a transverse molecular species asymmetry of PE in the plasma membrane of these cells which is altered after IFN treatment.

Cell Line↗
PubMed1985

Effect of ethanol on prostacyclin and thromboxane A2 synthesis in rat aortic rings in vitro.

Spontaneous 6-keto-PGF1 alpha and TXB2 levels in isolated rat aortic rings increased in a concentration dependent manner after a 0.5 hour incubation with moderate or high ethanol concentrations (11 mM to 218 mM). After a 1 hour incubation with moderate concentrations of ethanol less than or equal to 22 mM) spontaneous prostaglandin (PG) production did not increase although high concentrations (87 mM and 218 mM) increased both 6-keto-PGF1 alpha and TXB2 levels. Similarly, in the presence of 40 microM Na-arachidonate, high ethanol concentrations increased PG production after 0.5 and 1 hour incubation. In addition, either a 4 or an 8 hour exposure to high ethanol concentrations increased spontaneous PG production. A moderate concentration of ethanol (22 mM) increased the 6-keto-PGF1 alpha/TXB2 ratio whereas high levels (greater than or equal to 87 mM) depressed the ratio after 0.5 and 1 hour exposure. This effect was short-lived since after 4 or 8 hours incubation with high ethanol concentrations the 6-keto-PGF1 alpha/TXB2 ratio was markedly increased. The alcohol-induced changes in both spontaneous and arachidonate-stimulated PG levels were concentration dependent and related to the incubation time. Furthermore, these data suggest that there may be unbalanced production of PGI2 and thromboxane A2 in vascular tissue exposed to alcohol.

Animals↗
PubMed1983

Microfibrillar protein and phospholipid in granular corneal dystrophy.

Keratoplasty specimens from eight patients with granular corneal dystrophy (GCD) and age-matched control subjects were examined by combinations of immunohistological stains, transmission electron microscopy (TEM), and sodium dodecyl sulfate gel electrophoresis. Fresh frozen sections from corneas with GCD stained positively with antibodies to microfibrillar protein by immunofluorescence. Routine TEM disclosed that the granules had central electron-dense areas partially surrounded by 9- to 10-nm tubular microfibrils. Material eluted from corneas with GCD showed denser peptide bands at 65 and 110 kilo than in normal corneas. Stains were negative for elastin, amyloid, neutral lipids, cholesterol, and glycosaminoglycan. Luxol fast blue MBSN stain was strongly positive in the granules in all cases examined. Immunofluorescent stains were negative with antibodies to plasma fibronectin (cold insoluble globulin), laminin, collagens I to V, basement membrane proteoglycan, tropoelastin, and keratin. In two corneas with GCD an increased lipid content was found in every phospholipid class, although cholesterol content was unchanged. Alterations in the fatty acid profiles of phospholipids were also observed.

Contractile Proteins↗
PubMed1983

Mn2+-stimulated ATPase in rat brain.

Divalent cation ATPases were prepared from rat brain synaptic vesicles, synaptosomal plasma membranes, and plasma membranes from the brain stem and sciatic nerve and tested for optimal stimulation by Mn2+, Mg2+, or Ca2+. ATPase in the synaptic vesicle subfraction was optimally stimulated by Mn2+. All plasma membrane preparations were optimally stimulated by Mg2+. Separate Mn2+ and Mg2+ ATPases could not be distinguished by either chemical inactivation or substrate preference criteria. Mn2+ stimulated ATPase in the micromolar range and it is suggested that Mn2+ interaction with ATPase may be of physiological and/or toxicological importance by being related to the cellular metabolism of this element.

Adenosine Triphosphatases↗
PubMed1983

Ecto-5'-nucleotidase regeneration after chemical modification of the plasma membrane.

Treatment of the C6 glioblastoma cell with trinitrobenzenesulfonic acid (TNBS) resulted in the selective inactivation of ecto-5'-nucleotidase under conditions which maintained cell viability. Cells respond to ecto-enzyme inactivation by replacing 80% of lost activity within 24 hrs. A lag time of 4-6 hrs before ecto-5'-nucleotidase replacement began and its complete blockage by cycloheximide indicated that the source of replaced enzyme was de novo synthesis and not an intracellular pool. Release of 5'-nucleotidase activity into culture medium in the form of membraneous vesicles slowed during the active recovery period and then steadily increased with time as the plasma membrane enzyme level approached normal. TNBS did not exert a direct inhibitory action upon the exfoliative process as release of vesicular GM1 and protein were little affected. Decrease in exfoliated 5'-nucleotidase activity may be due to a selective conservation of the enzyme in the exfoliative process.

5'-Nucleotidase↗
PubMed1981

Exfoliation of membrane ecto-enzymes in the form of micro-vesicles.

Cultures from various normal and neoplastic cell lines exfoliated vesicles with 5'-nucleotidase activity which reflected the ecto-enzyme activity of the parent monolayer culture. The ratio of 5'-nucleotidase to ATPase activity in the microvesicles indicated that cellular ecto-ATPase was conserved in the exfoliative process. Phospholipids of the microvesicles contained significantly increased amounts of sphingomyelin and total polyunsaturated fatty acids. It was concluded that the shedded vesicles constituted a select portion of the plasma membrane. Examination by electron microscopy showed the vesicles had an average diameter of 500 to 1000 nm and often contained a second population of vesicles about 40 nm in diameter. As much as 70% of the plasma membrane ecto-5'-nucleotidase activity of a culture was released into the medium over a 24-h period. Phosphoesterhydrolases from C-6 glioma or N-18 neuroblastoma microvesicles dephosphorylated cell surface constituents when in contact with monolayer cultures. Exfoliated membrane vesicles may serve a physiologic function; it is proposed that they be referred to as exosomes.

Adenosine Triphosphatases↗
PubMed1981

Selective chemical modification of plasma membrane ectoenzymes.

As part of an investigation of the organization of cell surface macromolecular assemblies, we have treated intact central nervous system cells with chemical probes which react convalently with proteins and aminophospholipids. Selective alterations of the enzymatic activities of ecto-ATPases, ecto-5'-nucleotidases and cholinesterases were obtained under appropriate reaction conditions. The cross-linking reagent, 1,5-difluoro-2,4-dinitrobenzene, was a potent inactivator of ecto-ATPase of C6 glioblastoma, IMR-32 neuroblastoma and of a primary rat astroblast cell line (RB). Ecto-5'-nucleotidase and acetylcholinesterase were less sensitive to difluorodinitrobenzene. 1-Fluoro-2,4-dinitrobenzene at concentrations which inactivated ecto-ATPase had little effect on ecto-5'-nucleotidase. Conversely, 2,4,6-trinitrobenzenesulfonic acid was a potent inactivator of ecto-5'-nucleotidase but had no effect on ecto-ATPase. The difluorodinitrobenzene inactivation of ecto-ATPase and of ecto-5'-nucleotidase as well as the fluorodinitrobenzene inactivation of ecto-ATPase could be prevented by the presence of the appropriate substrates in the reaction medium. In the presence of protecting nucleotide substrates, a decrease in reactivity with proteins and lipids was observed when the isotopic probe fluorodinitro[3H]-benzene was used.

5'-Nucleotidase↗
PubMed1980

Comparison of 67Ga-citrate, 111In-bleomycin and 99mTc-citrate in the evaluation of pulmonary lesions.

A total of 128 patients were examined using three tumor localizing agents, 99mTc-citrate, 111In-bleomycin and 67Ga-citrate. All these patients had clinical symptoms of pulmonary disease and chest x-rays. Twenty-two patients were excluded from the original number. From the 106 remaining patients, 14 were benign cases and 92 malignant. A scan with a gamma-camera was performed 3 to 4 h following an intravenous injection of 15 mCi of 99mTc-citrate. Upon completion of this examination, the patient was given 2.5 mCi of 67Ga-citrate and 72 h later, scans were obtained using a 5in. rectilinear scanner. Fifteen days later 2.5 mCi of 111In-bleomycin was given and a similar examination to that of gallium was performed. In evaluating benign lesions, 99mTc-citrate gave no false positive results, while 111In-bleomycin gave 5% and 67Ga-citrate 20%. In the case of malignant lesions, 67Ga-citrate gave 79% true positive diagnosis, 111In-bleomycin 65% and 99Tc-citrate (of 57 evaluated patients) 46%.

Adult↗
PubMed1980

Preparation and spectroscopic characterization of molecular species of brain phosphatidylserines.

This study describes the first preparation and spectroscopic characterization of naturally occurring phospholipids separated according to degree of unsaturation. Phosphatidylserines (PS) have been prepared from bovine brain and shown to be pure by extensive thin layer chromatographic analysis as well as by infrared spectroscopy and fatty acid analysis. The PS has been separated according to degree of unsaturation and prepared using AgNO3-impregnated silica gel H thin-layer chromatography. Fatty acid analysis of the two principal PS subfractions indicates that they are enriched in the molecular species 1-octadecanoyl-2-docosahexaenoyl-sn-glycero-3-phosphorylserine and 1-octadecanoyl-2-octadecenoyl-sn-glycero-3-phosphorylserine. The identity of the two PS subfractions was further verified by rechromatographing on several thin layer systems and by infrared spectroscopy. With the use of a 100 MHz Fourier transform nuclear magnetic resonance (NMR) spectrometer, the spectra of bovine whole brain, white matter, gray matter, monoenoic, and hexaenoic PS were obtained. Distinct proton resonances were assigned to double bond protons, protons adjacent to a double bond, and protons between two double bonds, using fatty acid methyl ester standards. The various PS preparations gave different intensities of the various proton resonances which correlated with differences in fatty acid composition. The method provides a convenient, non-destructive spectroscopic method for distinguishing monoenoic and polyunsaturated species of intact phospholipids. Electron spin resonance studies of nitroxide-labelled cholestane in sonicated PS vesicles showed greater probe motion as the unsaturation of the acyl chains was increased. The hexaenoic PS vesicles were more fluid than monoenoic PS vesicles at all temperatures in the range 10-55 degrees C. These results suggest that neuronal membranes are more fluid than myelin membranes as neuronal membranes contain more hexaenoic phospholipids.

Animals↗
PubMed1978

Phospholipid changes in synaptic membranes by lipolytic enzymes and subsequent restoration of opiate binding with phosphatidylserine.

A study has been made of the role of phosphatidylserine in stereospecific opiate binding to neural membranes, utilizing specific lipolytic enzymes to attack the lipid. At very low concentrations phospholipase A2 from bee venom will preferentially hydrolyze C22:6-fatty acid; and even after a few percent of the total phosphatidylserine is hydrolyzed, opiate binding is greatly inhibited. The addition of brain phosphatidylserine will restore opiate binding; however, when the inhibition approaches 50% restoration is only partial. Exposure of membranes to phosphatidylserine decarboxylase will partially inhibit opiate binding; and the binding returns to the control level after the addition of phosphatidylserine. The partial inhibition of opiate binding by low concentrations of Triton X-100, which presumably remove lipids, can be partially reversed by phosphatidylserine. The binding of 3H-naloxone, an opiate antagonist, is similar to agonists in its behavior towards phospholipases and phosphatidylserine; however, binding of naltrexone, also an antagonist, is far less responsive. It is concluded that the phosphatidylserine associated with the opiate receptor is the C18:0, 22:6-diacyl form, which is closely associated with protein.

Animals↗