Peroxidase activity in mitochondria of Prototheca moriformis

Summary Peroxidase activity was investigated by the use of diaminobenzidine method in fixed cells of Prototheca moriformis. A strong peroxidase activity was observed in the mitochondria. DAB staining was unaffected by KCN, aminotriazole and antimycin A, but it was completely inhibited by methanol-nitroferricyanide.     

Effect of consumption of green and black tea on the level of various enzymes in rats

Drinking of both green and black tea as the only liquid ingested resulted in significant decreases in the activity of transketolase in whole blood of rats both before and after the in vitro addition of thiamin diphosphate. Liver transketolase activity was decreased only by green tea. Mucosal transketolase activity was not affected by either type of tea. The activity of lactate dehydrogenase (LDH) was not affected by either type of tea, while whole blood LDH was decreased by both green and black tea. Neither tea had any affect on mucosal alkaline phosphatase, but thiamin diphosphatase activity was decreased by both teas. An increase in liver total thiamin resulted from the drinking of both types of tea.     

Effect of consumption of green and black tea on the level of various enzymes in rats

Summary Drinking of both green and black tea as the only liquid ingested resulted in significant decreases in the activity of transketolase in whole blood of rats both before and after the in vitro addition, of thiamin diphosphate. Liver transketolase activity was decreased only by green tea. Mucosal transketolase activity was not affected by either type of tea. The activity of lactate dehydrogenase (LDH) was not affected by either type of tea, while whole blood LDH was decreased by both green and black tea. Neither tea had any affect on mucosal alkaline phosphatase, but thiamin diphosphatase activity was decreased by both teas. An increase in liver total thiamin resulted from the drinking of both types of tea.     

Activation of the electrogenic Na-pump of cardiac muscle fibres by ACh in K-free solutions

Summary The ionic mechanism of the membrane outward current (ACh-current) of bullfrog atrium muscle, induced by acetylcholine in K-free solution, was analyzed by a voltage-clamp experiment. The results suggested that the ACh-current was induced not only by an increase in K-conductance but also by an activation of the electrogenic Na-pump.Acknowledgment. This work was supported by a grant (257037) from the Ministry of Education of Japan.     

Inhibition of human platelet lipoxygenase by cyanide

Summary Potassium cyanide inhibited the lipoxygenase activity of a human platelet cytosolic fraction in a concentration-dependent manner (ID₅₀=2 mM). The inhibition was monitored by spectrophotometry (conjugation of diene bonds at 236 nm), by chromatography (inhibition of formation of 12-hydroperoxy eicosatetraenoic acid) as well as by measuring suppression of oxygen consumption. The lipoxygenase activity of intact platelets was also inhibited by KCN as evidenced by the reduction in 12-hydroxy-eicosatetraenoic acid formation in response to thrombin.Acknowledgments. This work was supported in part by NIH grant HL-14890. D.A. was a recipient of the Pharmaceutical Manufacturers Association Advanced Pre-Doctoral Fellowship.     

Monoamine oxidase activity of the hypothalamus and pituitary: alterations after pinealectomy, changes in photoperiod, or additions of melatonin in vitro.

Rat pituitary MAO activity was reduced by constant darkness and by additions of melatonin in vitro and was increased by constant light and by pinealectomy. Hypothalamic MAO activity followed the same pattern but was less dramatically affected. The data suggest that MAO may be a target enzyme for melatonin.     

Liver function during chronic renal failure in rabbits

In rabbits with chronic renal insufficiency the prothrombin index was increased by 25% and the alanine aminotransferase activity decreased by 20%; the results of other routine tests of hepatic function were not affected. The galactose elimination capacity was decreased by 12%, whereas the body clearance of antipyrine was unchanged. No change in hepatocytic structure was found.     

Inactivation of N-assimilating enzymes and proteolytic activities in wheat leaf extracts: Effect of pyridine nucleotides and of adenylates

Summary Nitrate reductase was protected from inactivation in wheat leaf extracts by NADH, while NADPH was less effective. NAD, NADP or adenylates did not affect nitrate reductase inactivation in vitro. Glutamine synthetase was more stable than nitrate reductase and was protected from inactivation by ATP. ADP, AMP or pyridine nucleotides had no or only a minor effect on the decrease of glutamine synthetase activity in extracts. The caseolytic activity extracted from senescing leaves was slightly decreased by NADH and NADPH but this effect was not sufficient to explain the stabilization of nitrate reductase by NADH. Oxidized pyridine nucleotides and adenylates had no major effect on the caseolytic activity under the conditions used.This work was supported by grant 3.067-0.81 from the Swiss National Science Foundation. Author for correspondence: U.F.     

Liver function during chronic renal failure in rabbits

Summary In rabbits with chronic renal insufficiency the prothrombin index was increased by 25% and the alanine aminotransferase activity decreased by 20%; the results of other routine tests of hepatic function were not affected. The galactose elimination capacity was decreased by 12%, whereas the body clearance of antipyrine was unchanged. No change in hepatocytic structure was found.     

Glycoprotein IIb/IIIa blockade inhibits platelet aminophospholipid exposure by potentiating translocase and attenuating scramblase activity

The present study investigated the mechanisms underlying the inhibition of platelet phosphatidylserine (PS) exposure by GPIIb/IIIa blockade. Platelet PS exposure induced by thrombin stimulation was cell-cell contact dependent. GPIIb/IIIa blockade by c7E3 or SR121566 inhibited thrombin-induced platelet PS exposure. Thrombin stimulation induced mild, while A23187 induced extensive platelet-derived microparticle (PDMP) generation. Thrombin-induced PDMP generation was not inhibited by GPIIb/IIIa blockade. Aminophospholipid translocase activity was reduced upon platelet activation by thrombin. The reduction of non-PS-exposing platelets was attenuated by GPIIb/IIIa blockade, while little translocase activity was seen in PS-exposing platelets. Thrombin increased scramblase activity slightly in non-PS-exposing platelets, which was inhibited by GPIIb/IIIa blockade, and markedly enhanced scramblase activity in PS-exposing platelets. Activation of platelet calpain and caspase-3 or cytosolic calcium mobilization were not altered by GPIIb/IIIa inhibition. Thus, GPIIb/IIIa blockade inhibits platelet PS exposure by enhancing translocase activity and attenuating scramblase activity, but does not inhibit PDMP generation. Received 13 December 2006; received after revision 5 February 2007; accepted 9 March 2007     

The ascendancy of the Laplace transform and how it came about

The modern Laplace transform is relatively recent. It was first used by Bateman in 1910, explored and codified by Doetsch in the 1920s and was first the subject of a textbook as late as 1937. In the 1920s and 1930s it was seen as a topic of front-line research; the applications that call upon it today were then treated by an older technique — the Heaviside operational calculus. This, however, was rapidly displaced by the Laplace transform and by 1950 the exchange was virtually complete. No other recent development in mathematics has achieved such ready popularisation and acceptance among the users of mathematics and the designers of undergraduate curricula.     

Adrenaline and the electrogenic sodium pump in Rana catesbeiana sympathetic ganglion cells.

The effect of adrenaline on the Na+-pump in bullfrog (Rana catesbeiana) sympathetic ganglion cells was studied by use of electrophysiological methods. The rate of removal of excess Na+ injected into a ganglion cell was increased by adrenaline. The K+-activated hyperpolarization of cell membrane, which might be produced by an electrogenic Na+-pump, was also increased by adrenaline. These results suggested that adrenaline was able to accelerate the Na+-pump, possibly the electrogenic Na+-pump.     

Systemic candidiasis from Candida albicans colonizing the gastrointestinal tract of mice.

Reproducible induction of systemic Candida infection was achieved by treating mice in which Candida colonization had been established in the gastrointestional tract by aminobenzylpenicillin treatment. Systemic candidiasis was induced in these mice by X-ray irradiation followed by immunosuppressive doses of dexamethasone or X-ray irradiation followed by immunosuppressive doses of trypan blue. Macrophages seem to play an important role in thie systemic infection.     

Über den Einfluss von Natriumsulfit,Natriumtellurit und Natriumselenit auf die Retention von Zink,Kadmium und Quecksilber im Organismus

Summary The influence of sodium sulfite, sodium tellurite and sodium selenite on the retention of zinc, cadmium and mercury in mice was studied. The retention of mercury was increased by sodium selenite and by sodium tellurite. The retention of cadmium was increased only by sodium selenite. Sodium sulfite did not influence the retention of metals studied. The retention of zinc was not influenced by any compounds used.     

The ascendancy of the Laplace transform and how it came about

The modern Laplace transform is relatively recent. It was first used by Bateman in 1910, explored and codified by Doetsch in the 1920s and was first the subject of a textbook as late as 1937. In the 1920s and 1930s it was seen as a topic of front-line research; the applications that call upon it today were then treated by an older technique — the Heaviside operational calculus. This, however, was rapidly displaced by the Laplace transform and by 1950 the exchange was virtually complete. No other recent development in mathematics has achieved such ready popularisation and acceptance among the users of mathematics and the designers of undergraduate curricula. Communicated by C. Truesdell     

Some characteristics of urokinase released in organ culture of human kidney

Summary Plasminogen activator produced in organ culture of human kidney, i.e. in the histotypical arrangement of the tissue, was partially purified by affinity chromatography on para-aminobenzamidine coupled to Sepharose by a 6-carbon spacer, followed by gel chromatography on Sephadex G-100. The molecular weight of 2 active peaks were 27,000 and 52,000 daltons respectively. It was inhibited by DFP and by IgG antiurokinase.This study was supported by grant from the Swedish Medical Research Council (B77-17X-04523-03B).     

The role of the autonomic nervous system in mediating pancreatic endocrine responses to arginine in the calf

Summary The release of insulin which occurred in response to arginine, in the conscious calf, differed from that which occurs in response to glucose in that it was not significantly affected by either adrenergic or muscarinic blocking agents. Release of pancreatic glucagon was reduced by pretreatment with phentolamine.This work was supported by the British Diabetic Association. It is a particular pleasure to acknowledge the skilled assistance provided by Messrs P. M. M. Bircham and G. P. McGregor.     

Participation of microtubules and microfilaments in the transcellular biliary secretion of immunoglobulin A in primary cultures of rat hepatocytes

Summary The biliary secretion of immunoglobulin A (IgA) in primary hepatocyte cultures was investigated by means of immunofluorescence. The characteristic accumulation of IgA in visible bile canaliculi was found to be strongly inhibited by vinblastine and colchicine or by cytochalasin B, but its surface binding was not.The author thanks Prof. Dr D. Mecke for his support and encouragement. The excellent technical assistance of Mrs M. Behringer and Mrs A. Schneck is gratefully acknowledged. The author is grateful to the BIOTEST Serum Institut (Frankfurt) for the kind gift of human IgA. This work was supported by the Deutsche Forschungsgemeinschaft.     

Activation of the electrogenic Na-pump of cardiac muscle fibres by ACh in K-free solutions.

The ionic mechanism of the membrane outward current (ACh-current) of bullfrog atrium muscle, induced by acetylcholine in K-free solution, was analyzed by a voltage-clamp experiment. The results suggested that the ACh-current was induced not only by an increase in K-conductance but also by an activation of the electrogenic Na-pump.     

Uptake and toxic effects of heavy metal ions: interactions among cadmium, copper and zinc in cultured cells

Absorption of metal ions by KB, HeLa and L-59 cells has been analyzed by atomic absorption spectrophotometry in the course of culture. Ions of the elements of the fourth period in the periodic chart such as Fe(II), Cu(II), Zn(II), Mn(II) and Ni(II) were not taken up, but those of the higher periods, such as Cd(II), Pb(II), Hg(II) and Ag(I) were were taken up easily. The uptake behavior by the cultured cells was in accordance with the characteristic features of metals, that metals in the fourth period are essential elements, and most of the elements of the fifth and the sixth periods are non-essential or toxic elements. The initial rate of Cd(II) uptake and the Cd(II) concentration has a sigmoidal relationship. Cd(II) was absorbed homotropically through cell membranes. The uptake of Cd(II) was specifically inhibited by Cu(II), but was affected little by Zn(II). The toxicity of Cd(II) to KB cells was greatly enhanced in the presence of Cu(II). On the contrary, the toxicity of Cd(II) was reduced by the addition of Zn(II) at several concentrations of Cd(II). The toxicity of Cd(II) did not depend on the amount of Cd(II) absorbed in the cells, but was determined by cofactors such as Cu(II). The interaction between Cd(II) and Cu(II) may be important for Itai-itai disease.