Search PubMed⌕ Search

Biomedical subjects

L Cohen

Publications and source records attributed to L Cohen.

At least 595 records · Page 33Linked to original sources
PubMed1975

Cell population kinetics in radiation therapy: relationship of cellular surviving fraction to RBE and OER.

A two-component multitarget model of cellular radiation lethality was used to predict the effects of changing LET and oxygenation. It was assumed that with high-LET radiations there is a greater probability of direct and irreparable events and that hypoxia reduces the number of chemically-mediated indirect and reversible events. Cellular surviving fractions, relative biological effectiveness, and oxygen enhancement ratios were computed on this basis and compared with published experimental data. The model and program were then used to generate isoeffect curves for photons and neutrons, oxygenated and anoxic states, and various specific tissues and tumors.

Cell Division↗
PubMed1975

Different effect of ouabain on the interferon production and action.

Ouabain, which inhibits specifically membrane-bound ATPase activity, also inhibits the establishment of the antiviral state induced by interferon. Once the antiviral state is established, ouabain is ineffective. This inhibitory effect is reversed by adding Na/K ions to the cells. On the contrary, interferon production is unaffected by the same concentrations of ouabain. It is of interest that in such interferon-yielding cells, ouabain decreases the antiviral state.

Adenosine Triphosphatases↗
PubMed1975

Silent acute pancreatitis with encephalomalacia mimicking hepatic coma.

A very rare case of acute pancreatitis with concurrent encephalomalacia and ascites mimicking hepatic coma is described. The possibliity that the pancreatitis was caused by the administration of chlorothiazide in a diabetic patient is suggested as possible etiology. It is emphasized that when a cirrhotic patient develops coma, the possibility of painless,silent pancreatitis with encephalomalacia as well as hepatic coma should be considered in the differential diagnosis.

Acute Disease↗
PubMed1975

Effect of pretreatment with prednisolone on enzyme efflux from isolated skeletal and heart muscle.

In a previous study, the efflux of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) which takes place from isolated mouse skeletal muscle was shown to be significantly reduced by pretreatment of the intact animal with diethylstilbestrol (DES). This compound is known to reduce the high serum enzymes present in patients with Duchenne's muscular dystrophy (DMD). Glucocorticoids also reduce the serum enzymes in DMD. The purpose of this study was to determine if pretreatment with the glucocorticoid, prednisolone, also lowered the efflux from isolated mouse skeletal and cardiac muscle. The results of these studies show that prednisolone pretreatment lowers the enzyme efflux from isolated skeletal muscle, but not from heart. There is an optimal dose which produces this reduction, which if exceeded, augments the efflux. Thus two agents are now known which lower the efflux of CPK and LDH from isolated skeletal muscle. These same two agents lower the high serum enzymes in DMD. This suggests, but does not prove, that the mechanism by which these agents lower the serum enzymes in DMD is by reducing enzyme efflux from skeletal muscle.

Animals↗
PubMed1975

Reduction of enzyme efflux from isolated skeletal muscle and heart by diethylstilbestrol.

It was previously shown that the efflux of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) from isolated mouse gastrocnemius was reduced 20% by a daily dose of 10 mug of diethylstilbestrol (DES) given for 14 or 21 days. The present study was designed to ascertain to what degree increasing doses of DES could suppress the CPK and LDH efflux from isolated skeletal muscle, and if DES affected heart in a similar manner. A total of 36 mice were injected with saline or 20, 100, 250 and 500 mug DES in saline daily for 14 days. The spontaneous efflux of CPK and LDH from the isolated gastrocnemius and heart was then compared in control and treated mice. The reduction in efflux was partially dose-dependent: increasing doses up to 100 mug DES per day, progressively reduced skeletal muscle efflux of CPK to 50% and LDH to 30%; higher doses had no additional effect. LDH efflux from heart was similarly reduced by DES, but over a narrower dosage range. This is the first agent shown to lower the spontaneous enzyme efflux from these two organs. These studies confirm that DES lowers the enzyme efflux from skeletal muscle; and though this effect is dose-related, the efflux could not be completely suppressed. The mechanism responsible for this reduction remains to be determined.

Animals↗
PubMed1975

Effect of gentamicin on renal function in the rat.

The functional correlates of gentamicin nephrotoxicity were studied in rats injected with gentamicin, 100 mg/kg b.wt. per day, for 1 to 6 days. After 4 days of injections, a significant decrease in urine osmolality was detected in association with a rise in blood urea nitrogen and serum creatinine. These changes became more pronounced after 5 days of injections. Injecting gentamicin for 3 to 5 days had no discernible effect on the capacity of the distal nephron to reabsorb solute free water during a saline load compared to the control group. Tubular secretion of para-aminohippurate (PAH) was significantly greater in rats injected with gentamicin for 4 to 5 days than in the control group. Increased uptake of PAH by renal cortical slices was detected after 1 day of gentamicin treatment and reached a peak effect after 5 days of injections. Probenecid completely inhibited the augmented PAH uptake. No stimulation of the organic base transport system was observed. Three days of gentamicin treatment did not alter intracellular water or electrolyte content of kidney cortical slices. The data suggest that gentamicin specifically stimulates the organic acid transport system and that this effect may represent an early functional correlate of gentamicin nephrotoxicity.

Aminohippuric Acids↗
PubMed1975

Lymphoid cell subpopulations. II. Characterization of cell populations responsible for syngery in the mixed lymphocyte interaction.

Mixtures of isogeneic lymph node cells (LNC) and thymocytes (TC) exhibit far greater responsiveness in the murine MLI, as measured by proliferation and development of cytotoxic effector cells, than either cell type cultured alone. Pretreatment of either lnc or TC with mitomycin-C or ultraviolet irradiation completely abolished their synergistic interaction. Administration of cortisone acetate to cell donors 20 hr before sacrifice reduced the capacity of LNC and enhanced the capacity of TC to synergize. The LNC and TC populations participating in synergy, were found to be thymus dependent. LNC were shown to be responsible for the bulk of proliferative and effector activity observed in synergizing cultures, whereas TC appeared to amplify the activation of LNC. These findings provide the basis for a three cell model of MLI responsiveness.

Animals↗
PubMed1975

Lymphoid cell subpopulations. I. Synergy between lymph node cells and thymocytes in response to alloantigens and mitogens.

Mixtures of isogenic thymocytes (TC) and lymph node cells (LNC) were shown to exhibit synergistic responsiveness to M and H-2 alloantigens in the mixed lymphocyte interaction (MLI). With respect to the kinetics and magnitude of proliferation and effector cell generation, the response occurring in synergizing cultures closely resembled that of optimal numbers of LNC or spleen cells (SC). In addition, the antigen specificity of effector cells generated by synergizing cultures was similar to that of effectors derived from cultures containing optimal numbers of responding SC. LNC-TC mixtures also exhibited synergy in response to the phytomitogens concanavalin A and pokeweed mitogen but not to phytohemagglutinin. Weakly positive synergy was observed in response to bacterial lipopolysaccharide. It is proposed that the phenomenon of synergy is not restricted to cultures containing mixtures of LNC and TC but also occurs in cultures containing optimal numbers of LNC or SC as a result of interactions between subpopulations of lymphocytes contained within these tissues.

Animals↗