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J Moss

Publications and source records attributed to J Moss.

At least 523 records · Page 29Linked to original sources
PubMed1981

Amino acid-specific ADP-ribosylation. Identification of an arginine-dependent ADP-ribosyltransferase in rat liver.

A partially purified protein preparation from rat liver catalyzed the ADP-ribosylation of low molecular weight guanidino compounds and proteins. Agmatine and arginine, previously shown to be effective acceptors for the guanidine-dependent erythrocyte ADP-ribosyltransferase, were used as acceptors by the rat liver enzyme; lysine, histidine, and serine were inactive. The product of the reaction between [adenine-U-14C]NAD and agmatine catalyzed by the rat liver enzyme co-chromatographed with [adenine-U-14C]ADP-ribose-agmatine which was synthesized by the erythrocyte transferase; in parallel assays, formation of this product was associated with stoichiometric release of [carbonyl-14C]nicotinamide from [carbonyl-14C]NAD. In the presence of histones or other proteins and [adenine-U-14C]NAD or [32P]NAD, the rat liver enzyme catalyzed the formation of a radioactive product which was precipitable by trichloroacetic acid. Digestion of the [adenine-U-14C]-labeled precipitate with snake venom phosphodiesterase released a labeled compound identified as 5'-AMP. These data are consistent with the conclusion that a mono-(ADP-ribosyltransferase) is present in rat liver which utilizes guanidino compounds such as arginine as ADP-ribose acceptors. The ADP-ribose-glutamate bond has been shown to exist in rat liver. Since the catalytic sites of each transferase can accommodate and thus ADP-ribosylate only one specific amino acid, a family of site-specific transferases must be present. The availability of multiple site-specific transferases permits the cell to exert further control over ADP-ribosylation.

ADP Ribose Transferases↗
PubMed1981

On the mechanism of preadipocyte differentiation. Masking of poly(ADP-ribose) synthetase activity during differentiation of 3T3-L1 preadipocytes.

Differentiation of 3T3-L1 preadipocytes, induced by methylisobutylxanthine (MIX), dexamethasone (DEX), and insulin, produces cells with the morphological and biochemical characteristics of adipocytes. Poly(ADP-ribose) synthetase activity in 3T3-L1 cells treated with MIX, DEX, and insulin underwent an abrupt decrease in activity, remained low for several hours, and then increased; this rise was delayed by readdition of MIX, DEX, and insulin. The drop of synthetase activity represents the earliest alteration of a specific enzyme yet detected during the differentiation of 3T3-L1 cells. Nondifferentiating 3T3-C2 control cells do not exhibit changes in poly(ADP-ribose) synthetase activity when treated with MIX, DEX, and insulin. The transient reduction in poly(ADP-ribose) synthetase activity in 3T3-L1 cells occurred prior to the appearance of the adipocyte phenotype induced by the above agents and was not observed when preparations were assayed in the presence of DNase I. It is evident that poly(ADP-ribose) synthetase activity was masked following treatment with MIX, DEX, and insulin since the synthetase is sensitive to agents that affect the physical properties of DNA. This transient reduction in activity may be an early event in differentiation which reflects changes in chromatin structure.

1-Methyl-3-isobutylxanthine↗
PubMed1981

ADP ribosylation of membrane proteins from human fibroblasts. Effect of prior exposure of cells to choleragen.

Major labeled bands of Mr = 42,000 and 47,000 were observed on sodium dodecyl sulfate polyacrylamide gel electrophoresis of human skin fibroblast membranes incubated with choleragen and [32P]NAD. Prior incubation of intact fibroblasts with choleragen blocked specifically the subsequent in vitro labeling of these two proteins. The effect of choleragen was dependent on time, temperature, and toxin concentration. Neither the choleragen A subunit nor the B subunit nor the A1 peptide could replace the holotoxin in cell incubations. Inhibition of subsequent in vitro labeling by prior exposure of cells to choleragen was correlated with increased cellular cAMP. Incubation of fibroblasts with prostaglandin E1 and isoproterenol, which activate adenylate cyclase by different mechanisms, did not block subsequent labeling with choleragen and [32P]NAD. The results suggest that proteins of Mr = 42,000 and 47,000 may be in vivo substrates for choleragen in human fibroblasts.

Adenosine Diphosphate Ribose↗
PubMed1981

Histone-dependent and histone-independent forms of an ADP-ribosyltransferase from human and turkey erythrocytes.

An ADP-ribosyltransferase from turkey erythrocytes, which catalyzes the mono(ADP-ribosylation) of guanidino compounds such as arginine and of many purified and crude cellular proteins, appears to exist both in high-activity, histone-independent and low-activity, histone-dependent forms. At low salt concentrations, the activity of the transferase with agmatine as acceptor was less than 10% that observed in the presence of 200 mM NaCl. In the absence of salts, ADP-ribosylation of agmatine was stimulated greater than 10-fold by histones, and activity approached that observed with high salt concentration; under these conditions, the histones did not serve as ADP-ribose acceptors themselves. Histone also activated the highly purified ADP-ribosyltransferase from human erythrocytes. Enzyme activity was increased in the presence of salt and was then relatively independent of histones. DNA was not required for the stimulation of ADP-ribosylation by histone; incubation of the transferase and histone with DNase did not significantly decrease enzymatic activity. Additional DNA in the assay decreased the effect of histone. The erythrocyte ADP-ribosyltransferase from diverse species thus appears to exist in two forms: one is dependent on histones for activity and one which, in the presence of salt, has high intrinsic activity and is independent of histone. The fact that the active forms of the transferase generated in the presence of salt or histone have similar catalytic activity suggests that these forms of transferase may be identical. It would appear that the enzymatic activity of transferase from different species may be controlled by histones.

ADP Ribose Transferases↗
PubMed1981

Role of histamine in the hypotensive action of d-tubocurarine in humans.

The administration of d-tubocurarine (dTc) to animals and humans has been reported to produce hypotension. Experiments in animals suggest that the hypotension is a result of both ganglionic blockade and histamine release. In order to determine the role of histamine release in dTc-induced hypotension in humans, the authors developed a sensitive radioenzymatic assay for plasma histamine and measured plasma histamine following dTc administration (0.25-0.75 mg/kg) to 21 surgical patients. While neither fentanyl (3 microgram/kg) nor thiopental (6 mg/kg) produced a significant change in plasma histamine, dTc caused a dose-dependent increase in plasma [dose dTc vs. log (plasma histamine), r = 0.62 P less than 0.003]. The log (plasma histamine) correlated with the dTc-induced hypotension (r= 0.61, P less than 0.005). The data suggest that histamine release is an important factor in the hypotension accompanying dTc administration in humans.

Blood Pressure↗
PubMed1981

The use of H1 and H2 histamine antagonists with morphine anesthesia: a double-blind study.

High doses of morphine can produce significant cardiovascular effects generally attributed to histamine release. The authors examined the possibility that H1 and H2 histamine antagonists might prove beneficial in preventing these responses. In a randomized double-blind study, four groups of 10 patients each received 1 mg/kg morphine and either a placebo, diphenhydramine (H1), cimetidine (H2), or both of the histamine antagonists. The morphine-placebo group demonstrated a marked elevation in plasma histamine levels (880 +/- 163 to 7437 +/- 2684 pg/ml), a decrease in systemic vascular resistance (SVR) (15.5 to 9.0 l torr/(l . min-1) and diastolic BP (71 +/- 3 to 45 +/- 4 torr) and an increase in cardiac index (CI) (2.4 +/- 0.2 to 3.0 +/- 0.21 . min-1 . m-2). The administration of either cimetidine or diphenhydramine with morphine provided minimal protection. Those patients who received morphine and both antagonists demonstrated significant attenuation of these responses (CI 2.5 +/- 0.2 to 2.5 +/- 0.1 l . min-1 . m-2; SVR 17.4 to 14.6 torr/(l . min-1) although plasma histamine levels showed a comparable increase (1059 +/- 222 to 7653 +/- 4242 pg/ml). These data demonstrate directly that many of the hemodynamic effects of morphine can be attributed to histamine release. They further demonstrate that significant hemodynamic protection can be obtained by the use of histamine antagonists and the combination of H1 and H2 antagonists is superior to either given alone.

Blood Pressure↗
PubMed1981

Hormonal and hemodynamic profile of an anaphylactic reaction in man.

A 28-year-old female undergoing elective total hip replacement experienced an anaphylactic reaction to succinylcholine. Hemodynamics, plasma histamine and catecholamines were measured. The tachycardia experienced during the reaction appeared to be secondary to the sympathoadrenal response rather than a direct chronotropic effect of histamine.

Adult↗
PubMed1981

Attenuation of the stress response to cardiopulmonary bypass by the addition of pulsatile flow.

The effect of pulsatile flow during cardiopulmonary bypass on the hormonal stress response was studied in 26 patients. Thirteen had routine and 13 had pulsatile bypass with an average pulse pressure of 30 mm Hg. Plasma vasopressin levels were significantly elevated during bypass in both groups, but were lower with pulsation (66 +/- 11 vs 36.3 pg/ml, p less than 0.05). Epinephrine levels increased in both groups during bypass, but were higher after bypass (1179 +/- 448 vs 713 +/- 140 pg/ml, p less than 0.05) and in the recovery room (1428 +/- 428 vs 699 +/- 155 pg/ml, p less than 0.05) in the nonpulsatile group. The same response was noted in the norepinephrine levels (924 +/- 225 vs 465 +/- 90 pg/ml, p less than 0.05; 1015 +/- 491 vs 717 +/- 112 pg/ml, p less than 0.05). There were no significant changes in renin activity in either group, but the increase after cardiopulmonary bypass was greater in the nonpulsatile group (2.0 +/- 0.7 vs 1.36 +/- 0.4 ng/ml/hr, NS). These data suggest that pulsatile flow significantly attenuates the vasopressin and catecholamine stress response to cardiopulmonary bypass. This may explain the increased flow requirements and better tissue perfusion and organ function and the decreased incidence of postoperative hypertension after bypass using pulsatile flow.

Blood Gas Analysis↗
PubMed1981

Regulation of collagen production by the beta-adrenergic system.

The suppression of collagen production by increasing the cyclic (c) AMP content of cultured cells was examined vis-à-vis the beta-adrenergic system. Cultured human fetal lung fibroblasts incubated for 6 h with the beta-agonists isoproterenol or epinephrine produced approximately 30% less collagen per cell than in the absence of the hormones. To demonstrate that the beta-agonists were operating by their interaction with the beta-receptor to stimulate adenylate cyclase to increase the intracellular content of cAMP, d- and l-isoproterenol were incubated separately with the cultured cells. Only l-isoproterenol increased intracellular cAMP and decreased collagen production. While 20 nM l-isoproterenol was effective, the d-isomer was ineffective even at 2muM. An increase in cAMP from 40 to 73 pmol/mg protein was effective in suppressing collagen production; increasing the cAMP content to much higher levels had little additional effect on collagen production. 3-Isobutyl-1-methylxanthine, an analog of theophylline that inhibits phosphodiesterase, potentiated the effect of isoproterenol in suppressing collagen production. Further support for the concept that isoproterenol suppressed collagen production by acting through the beta-receptor was provided by the finding that only the l-isomer of propranolol, a beta-blocker, was effective in blocking both the increase in intracellular cAMP and the suppression of collagen production caused by isoproterenol. These results demonstrate that collagen production in human fibroblasts can be regulated by the beta-adrenergic system and indicate that when the cAMP content is increased beyond a threshold value, collagen production is suppressed. Since collagen production is sensitive to the small changes of cAMP content of cells brought about by beta-stimulation in cultured cells, the results point to a possibly important mechanism for the regulation of collagen production in the body.

Cells, Cultured↗
PubMed1981

The prevalence of conduction defects and cardiac arrhythmias in progressive systemic sclerosis.

A prospective noninvasive electrocardiographic study was done on 50 patients with progressive systemic sclerosis. Thirty-two percent had abnormalities on the resting electrocardiogram, of which the commonest were left anterior fascicular block (16%) and first-degree heart block (8%). The 24-hour ambulatory continuous tape-recorded electrocardiograms showed serious abnormalities in 62% of the patients: supraventricular tachycardias (32%), conduction disturbances (14%), coupled ventricular extrasystoles (20%), and ventricular tachycardia (10%). Intracardiac electrophysiologic data were obtained in 20 of these patients, and functional abnormalities of the sinus node, atria, and atrioventricular node were noted in seven, nine, and 10 patients, respectively. One patient had prolonged His-Purkinje conduction time. Of the 20 patients who had electrophysiologic studies, only six had entirely normal findings. These results suggest a much higher degree of cardiac involvement in progressive systemic sclerosis than previously believed. We postulate that the first-degree heart block and supraventricular tachycardias may derive from a similar pathologic process, namely, fibrous atrophy of the proximal atrioventricular node.

Adult↗
PubMed1981

Renal function and stress response during halothane or fentanyl anesthesia.

The effects of anesthesia on hormonal stress response and renal function were measured before institution of cardiopulmonary bypass in two groups of patients undergoing elective coronary artery surgery. Group 1 (10 patients) received fentanyl, 100 microgram/kg, and N2O/O2; group 2 (12 patients) received halothane and N2O/O2. Patients in group 1 showed no significant changes in plasma levels of vasopressin, renin, or aldosterone during anesthesia or operation. This same group, however, demonstrated significant decreases in plasma levels of cortisol (8.4 +/- 1 to 4.2 +/- 1 microgram%, p less than 0.01), epinephrine (260 +/- 72 to 97 +/- 28 pg/ml, p less than 0.05), and norepinephrine (715 +/- 177 to 322 +/- 46 pg/ml, p less than 0.05) during operation. This was accompanied by an increase in urine volume (2.1 +/- 0.8 to 7.6 +/- 2 ml/min, p less than 0.05), a decrease in urine osmolality (610 +/- 82 to 166 +/- 60 mOsm/kg, p less than 0.01), and urine Na+ (54 +/- 12 to 16 +/- 4 meq/L, p less than 0.01) and no change in creatinine clearance. In contrast, in the group 2 patients during operation plasma levels of cortisol (11.7 +/- 2 to 31.1 +/- 2 microgram%, p less than 0.01), aldosterone (60 +/- 14 to 106 +/- 2 pg/ml, p less than 0.01), and vasopressin (10.4 +/- 1 to 23.3 +/- 3 pg/ml, p less than 0.01) all increased. This was accompanied by a significant decrease in creatinine clearance (148 +/- 52 to 92 +/- 12 ml/min/m2, p less than 0.05). The data demonstrate that high dose fentanyl anesthesia can significantly attenuate the hormonal stress response to operation and preserve renal function. They also suggest that decreases in renal function observed with anesthesia and operation may be a reflection of the hormonal changes associated with surgical stimulation.

Aldosterone↗
PubMed1980

Activation of choleragen by thiol: protein disulfide oxidoreductase.

In the presence of thiols such as glutathione or dithiothreitol, choleragen catalyzes the NAD-dependent ADP-ribosylation of arginine and proteins; thiols reduce the disulfide linking the A1 and A2 peptides of the A protomer of the toxin, releasing the active A1 peptide. Homogeneous thiol:protein disulfide oxidoreductase from bovine liver, in the presence of limiting concentrations of glutathione or dithiothreitol, increased the rate of activation of choleragen and its A protomer. The ability of oxidoreductase preparations to activate choleragen co-chromatographed with oxidoreductase protein on gel permeation columns and was proportional to the concentration of oxidoreductase in the assay. In the presence of oxidoreductase, the concentrations of glutathione and dithiothreitol necessary for activation were reduced. Thiol:protein disulfide oxidoreductase could play a role in the reduction of choleragen and release of the catalytically active A1 peptide.

Animals↗
PubMed1980

Effects of nucleoside triphosphates on choleragen-activated brain adenylate cyclase.

To investigate the effects of nucleoside triphosphates on the activation of adenylate cyclase by choleragen and on the stability and catalytic function of the choleragen-activated enzyme, we treated samples of particulate preparation from bovine brain successively in three separate incubations with extensive washing between each step. In incubation I, choleragen and NAD were pesent to activte the adenylate cyclase. In incubation II, conditions were varied to assess enzyme stability. Finally, adenylate cyclase activity was assayed with ATP or adenylyl imidodiphosphate [App-(NH)p] as the substrate. Even when assays contained an optimal concentration of GTP, nucleoside triphosphate (plus a regenerating system) was required in incubation I for maximal choleragen activation; in order of effectiveness, GTP > ITP > ATP greater than or equal to CTP = UTP. During incubation II (at 30 degrees C), activity of the choleragen-treated fractions was essentially completely stable when 100 microM GTP (plus a regenerating system) was present. ITP and ATP were less effective. Activation produced by guanylyl imidodiphosphate was more stable than that resulting from choleragen, GTP, and NAD. After activation of membranes with choleragen, NAD, and GTP, nucleoside triphosphate plus a regenerating system (but not NAD or additional choleragen) was essential for expression of maximal activity. In order of effectiveness, GTP > ITP > ATP greater than or equal to CTP = UTP. It appears that GTP, which was effective in micromolar concentrations, plays an important role not only in the activation of adenylate cyclase by choleragen but also in the stabilization and expression of the catalytic function of the activated enzyme.

Adenosine Triphosphate↗