Kinetic analysis of anaerobic metabolism in rats during acute cyanide poisoning

In order to investigate the changes in energy metabolism during acute anoxia, blood levels of various metabolites were analysed in cyanide-poisoned rats. After intraperitoneal injection of a sublethal dose of potassium cyanide (5 mg/kg), blood samples were obtained by cervical dislocation at intervals of 5 min until 30 min. Lacatate and lactate/pyruvate ratio (L/P) in plasma concomitantly changed with cyanide; increased rapidly at 5 min, remained fairly constant until 20 min and then began to decrease at 25 min. In contrast, the products of ATP degradation, oxypurines and inorganic phosphate (Pi), increased gradually until 25 min and then began to decrease at 30 min. Allantoin in plasma scarcely increased throughout the experiments. The results indicate that the rapid activation of anaerobic ATP formation by glycolysis was followed by the increase in ATP degradation in cyanide-poisoned rats. Thus, increase in plasma oxypurines could be regarded as an indicator for severe anoxic states in tissues with massive ATP degradation.     

Lateral conductance parallel to membrane surfaces: effects of anesthetics and electrolytes at pre-transition.

The effects of dilute salts and anesthetics were studied on the impedance dispersion in the dipalmitoylphosphatidylcholine (DPPC) liposomes. Below the pre-transition temperature, the apparent activation energy for conductance in DPPC-H2O without salts was equivalent to pure water, 18.2 kJ mol-1. This suggests that the mobile ions (H3O+ and OH-) interact negligibly with the lipid surface below the pre-transition temperature. At pre-transition temperature, the apparent activation energy of the conductance decreased by the increase in the DPPC concentrations. The effects of various salts (LiCl, NaCl, KCl, KBr, and KI) on the apparent activation energy of the conductance were studied. Changes in anions, but not in cations, affected the activation energy. The order of the effect was Cl- less than Br- less than I-. Cations appear to be highly immobilized by hydrogen bonding to the phosphate moiety of DPPC. The smaller the ionic radius, the more ions are fixed on the surface at the expense of the free-moving species. The apparent activation energy of the transfer of ions at the vesicle surface was estimated from the temperature-dependence of the dielectric constant, and was 61.0 kJ mol-1 in the absence of electrolytes. In the presence of electrolytes, the order of the activation energy was F- greater than Cl- greater than Br- greater than I-. When the ionic radius is smaller, these anions interact with the hydration layer at the vesicle surface and the ionic transfer may become sluggish. In the absence of electrolytes, the apparent activation energy of the dielectric constant decreased by the increase in halothane concentrations. In the presence of electrolytes, however, the addition of halothane increased the apparent activation energy. We propose that the adsorption of halothane on the vesicle surface produces two effects: (1) destruction of the hydration shell, and (2) increase in the binding of electrolytes to the vesicle surface. In the absence of electrolytes, the first effect predominates and the apparent activation energy is decreased. In the presence of electrolytes, the latter effect predominates and the apparent activation energy is increased.     

Studies on the Neutralization of Herpes Simplex Virus

Herpes virus was reacted with an early rabbit antiserum containing predominantly complement-requiring neutralizing (CRN) antibody to produce CRN-antibody-sensitized virus (SV), and the action of complement (C') upon SV was studied. Reduction of infectivity due to C' was about equal with undiluted and 1000-fold diluted SV. Even higher dilutions which contained about 10 to 100 infectious units per 0.05 ml were also completely inactivated by C'. Kinetic experiments revealed that the velocity of titer reduction in the presence of C' of 100-fold diluted SV was not slower than that of undiluted SV. When SV was first treated with C' and then diluted 100-fold, the surviving virus showed but a slightly reduced efficiency of filtration through the 0.45 μ Millipore membrane as compared with SV first diluted 1: 100 and then treated with C'. The titer reduction of SV–C'1 complexes in the presence of C'4 followed a one-hit curve. These results indicated that the reduction of infectivity of SV due to C' was not a result of immunoaggregation of infectious SV. Alternative possible mechanisms of the action of C' are discussed.     

Neutralizing Activities of Early and Late IgG Fragments from Rabbits Immunized with Herpes Simplex Virus

Rabbits immunized with herpes virus were bled periodically and bivalent and univalent fragments of IgG from each serum sample were prepared by enzymatic digestion. The 2-week F(ab′)₂ showed a low neutralizing activity only after addition of anti-IgG. F(ab′)₂ of the 4-week serum retained almost all of the neutralizing activity of IgG, while its univalent fragments demonstrated none even when tested with anti-IgG. In contrast to these early IgG fragments, univalent fragments of the 9-week and 20-week IgG neutralized the virus to considerable extents in the absence of anti-IgG; after addition of anti-IgG the activity equaled that of intact IgG in the cases of Fab′ and Fab-II, though the activity of Fab-I was relatively low. The three univalent fragments were all sensitive to heating at 70 C and to ultraviolet irradiation, whereas intact IgG resisted these treatments. F(ab′)₂ was resistant to the heating and less sensitive to ultraviolet irradiation than univalent fragments. Neutralization kinetic curve experiments to test blocking effects of IgG fragments against the neutralization by intact IgG suggested that the early Fab′ did combine with the virus and that the late Fab′ exerted a higher blocking effect than the early Fab′.     

Possible involvement of folate cycle in the pathogenesis of amyotrophic lateral sclerosis

The folate cycle, which has a close correlation with nucleic acid synthesis as well as with sulfur amino acid metabolism, may have some bearing on the pathogenesis of amyotrophic lateral sclerosis. The folate cycle hypothesis offers a unified explanation of the reduction of RNA and the elevation of taurine in nervous tissue of this disease.Dedicated to K. A. C. Elliott on his 80th birthday.     

A thermostable acid alpha-glucosidase from Tetrahymena thermophila: purification and characterization

An acid alpha-glucosidase (EC 3.2.1.20) was purified to homogeneity from the culture medium of Tetrahymena thermophila CU 399. Its general molecular, catalytic and immunological properties were compared to those of the T. pyriformis W enzyme. The enzyme from T. thermophila was a 105-kD monomer and the N-terminus (25 amino acid residues) displayed some homology with that of T. pyriformis enzyme. The purified enzyme was most active at 56 degrees C and showed resistance to thermal inactivation. The acid alpha-glucosidase appears to have alpha-1,6-glucosidase as well as alpha-1,4-glucosidase activity. The Km values determined with p-nitrophenyl-alpha-glucopyranoside, maltose, isomaltose and glycogen were 0.7 mM, 2.5 mM, 28.5 mM and 18.5 mg/ml, respectively. The enzyme was antigenically distinct from T. pyriformis acid alpha-glucosidase.