Energy-induced modulation of the kinetics of oxidative phosphorylation and reverse electron transfer

The kinetics of ATP synthesis by bovine heart submitochondrial particles (SMP) are modulated by the rate of energy production by the respiratory chain between two fixed limits characterized by apparent KmADP = 2-4 microM and Vmax approximately 200 nmol of ATP min-1 (mg of SMP protein)-1 at low energy levels and apparent KmADP = 120-160 microM and Vmax = 11,000 nmol of ATP min-1 (mg of SMP protein)-1 at high energy levels. These data indicate that KmADP and Vmax increase approximately 50-fold each; therefore, there is essentially no change in the catalytic efficiency of the ATP synthase complex in going from one extreme to the other. At intermediate rates of energy production, the kinetic data required introduction of a third, intermediate KmADP. A KmADP of 10-15 microM fitted all the data reported here and previously [Matsuno-Yagi, A., & Hatefi, Y. (1986) J. Biol. Chem. 261, 14031-14038]. However, this is not meant to suggest that there is a fixed intermediate KmADP, as the transition from one fixed limit to the other may be fluid or involve more than one intermediate state. In addition, it has been shown that kinetic plots of SMP-catalyzed and ATP-driven reverse electron transfer from succinate to NAD are curvilinear and resolvable into a minimum of two apparent KmNAD values of about 20-30 and 200-300 microM. These results have been discussed in relation to the three potentially active catalytic sites of F1-ATPase and the structure of the NADH:ubiquinone oxidoreductase complex, the curvilinear kinetics of ATP hydrolysis, and changes in KmADP and KmPi in photophosphorylation as affected by the duration and intensity of light.     

Peroxidase activity in human red cell: a biological model for excited state molecules generation.

The presence of enzymically generated triplet acetone in red cells and energy transfer to eosin, rose bengal and 9,10-dibromoanthracene-2-sulfonate was indicate by: (1) product distribution; (2) K_ET τ_o, similar to the 2-methylpropanal/peroxidase/O₂ system; (3) correlation between hemolysis, oxygen uptake and photon emission; (4) membrane protection by energy acceptors, and (5) by comparison of the 2-methylpropanal/peroxidase/O₂ system with 2-methylpropanal/red cells/membranes/O₂ and 2-methylpropanal/acid extractable protein from red cells membrane/O₂ systems, which have a high peroxidase activity.This is the first report of a biological system producing a photohemolysis effect in the dark.     

Use of acyclovir in the prevention of herpes infections after allogenic bone marrow grafts

In a double-bind controlled study, oral Acyclovir has been compared to a placebo in a series of 39 consecutive patients undergoing bone marrow transplantation. A dose of 200 mg was given every 6 h from day 8 to day 35 after transplantation. Pharmacokinetic studies have shown the good absorption of the drug despite intestinal damage related to chemoradiotherapy or gut graft-versus-host disease (GVHD), there was no sign of toxicity. The protection against herpes simplex virus (HSV) infection was complete in the treated group when compared to the control group even in patients with high anti-HSV antibody titres. The same protection was observed against cytomegalovirus (CMV) infection. The incidence of HSV and CMV was the same in both groups after treatment ended. This study confirms the efficacy of Acyclovir against HSV infection and possibly against CMV infection when it is given prophylactically after bone marrow transplantation.     

Polyacetylenes in Hawaiian bidens

Leaves and roots of 19 species and six subspecies of Hawaiian Bidens were examined for polyacetylenes. Eleven C₁₃ hydrocarbons, aromatic and thiophenyl derivatives, one C₁₄ tetrahydropyran and three C₁₇ hydrocarbons were isolated all identified. All can be derived from a common precursor, oleic acid. Polyacetylenes were not detected in the leaves of 13 taxa although they are found in the roots of all. The occurrence of 2-[2-phenyl-ethyne-1-yl]-5 acetoxymethyl thiopene in Bidens has not been previously reported. Its ubiquitous presence is consistent with other evidence that the Hawaiian species are all derived from a single ancestral immigrant to the islands. Most taxa could be distinguished by their complement of polyacetylenes in roots and leaves. No variation was found to occur within taxa except in B. torta, in which each population had a unique array of polyacetylenes. Above the species level there appeared to be no taxonomically significant pattern to the distribution of polyacetylenes in this group.     

Influence of Nitrate and Sulfate on the Anaerobic Treatment of Pharmaceutical Wastewater

Anaerobic treatment of wastewater from the pharmaceutical industry, which contained about 3.2 g/L of sulfate, was carried out in an Upflow Anaerobic Sludge Blanket (UASB) reactor. After a startup period of 120 days, a chemical oxygen demand (COD) removal efficiency of more than 90 % was obtained along with an organic loading rate (OLR) of 1.5 g COD/(L day). During the same period, the sulfate removal was about 90 %. However, the performance of the reactor was affected when the loading rate was increased to 2.09 g COD/(L day). It was found that the accumulation of sulfides, combined with a decrease in the pH, affected the reactor performance. In batch reactor studies with pharmaceutical wastewater it was observed that methane production began only after the initiation of nitrate consumption. The denitrification process can inhibit sulfate reduction at high nitrate concentrations, but compared to reactors without nitrate, the sulfate reduction process and sulfide formation were quickly initiated at low nitrate concentrations. The methanogenic activity was however affected by the presence of more than 2 g/L of sulfate.     

Effect of hyperthermia on growth of Ehrlich ascites tumor cells

Hyperthermic treatment at 43 degrees C suppressed the growth of Ehrlich ascites tumor (EAT) cells in vitro. Incubation of EAT cells at 43 degrees C for as little as 1.5 h totally abolished the transplantability of the tumor. At the same time, the rate of cellular glucose uptake, the density of glucose transporter on the cells as well as the extent of thymidine, uridine and leucine incorporation were significantly reduced.     

In vitro study of the modification by bleomycin of thymidine phosphorylation activity in lectin-stimulated normal human lymphocytes

We have investigated the effect of bleomycin (BLM) on thymidine phosphorylation in lectin-stimulated normal human lymphocytes. BLM reduces thymidine phosphorylation by decreasing the activity of thymidine kinase (TK). Accordingly, polyacrylamide gel electrophoresis (PAGE) of extracts of cells incubated for 48, 72 and 96 h showed here that this activity dropped 48, 65 and 67% respectively. The electrophoretic profiles of TK activity were similar but different in amplitude. These effects of the BLM were confirmed firstly by direct measurement of TK activity, secondly by amount of 3H-thymidine incorporation in the cultures before cell lysis. Both the measurement of TK activity and 3H-thymidine incorporation were correlated.