Combined use of COSY and double quantum two-dimensional NMR spectroscopy for elucidation of spin systems in polymyxin B

Two-dimensional single quantum correlation NMR spectroscopy (COSY) and two-dimensional double quantum NMR spectroscopy (2QT) are used to study spin systems in the 1H NMR spectrum of polymyxin B. Because of different frequency relationships, the two types of two-dimensional NMR experiments are found to be highly complementary. This is demonstrated by combined use of COSY and 2QT spectroscopy to obtain a complete analysis of the complicated spectral overlap which occurs in the 1H NMR spectrum of polymyxin B.     

Effect of temperature on embryonic development and reproduction of the freshwater snailLymnaea luteola Troshel (Gastropoda), a vector of schistosomiasis

The effect of temperature on embryonic development and reproduction ofLymnaea luteola was studied. This snail did not develop completely and failed to reproduce at 15 °C and 40 °C. The temperature range of 25 °C–35 °C was observed to be optimum for development and reproduction of this snail. The utility of this study in predicting seasonal fluctuations of snail population in nature is discussed.     

Studies on the partial structure of the O-antigen of Vibrio cholera Ogawa G-2102

Detailed information was obtained regarding the partial structure of the lipopolysaccharide (LPS), containing glucose, glucuronic acid, 2-amino-2-deoxy-glucose, L-glycero-D-gluco-heptose, and small proportions of L-glycero-D-manno-heptose, mannose, and galactose, isolated from Vibrio cholera Ogawa G-2102. Structures of three oligosaccharides were determined. Results of deamination experiments established the sequence of the linkages between the amino sugar and heptose residues in the O-antigenic polysaccharide.     

Renal Failure After Radiological Contrast Media

Over a 12-month period four patients developed acute renal failure after undergoing radiological investigations using contrast media. Though the incidence of serious complications is low, the possibility of adverse side effects must be weighed against the usefulness of the information provided by these techniques.     

Methionine-oxidized horse heart cytochromec. III. Ascorbate reduction and the methionine-80-sulfur-iron linkage

The ascorbate reduction of the CT-cytochromes—two chemically generated forms of horse heart cytochrome c, F^III and F^II, with both methionines, 80 and 65, as methionine sulfoxides, no iron-sulfur linkage, and potentiometric and physiological oxidoreduction properties distinct from those of the native protein and one another (J. Pande et al., 1987)—has been investigated using a stopped-flow technique. The reaction was monitored at 550 nm, and studies were conducted in 10 mM phosphate +0.17 M NaCl buffer,pH 7.4. Both CT-cytochromes are reduced by triphasic profiles, a faster and an intermediate ascorbate-dependent reaction and a slow, ascorbate-independent process. Both CT-cytochromes contain three molecular forms in slow equilibrium, two reducing directly by reaction with ascorbate and a third through conversion to one of the reducible forms. Like the reaction of the native protein, the ascorbate dependence of both the rapid and the intermediate process is nonlinear, approaching saturation values at high concentrations. The ascorbate profiles of the pseudo-first-order reduction constants are typical of the model for the reduction reaction of the unmodified protein, binding followed by a first-order reduction reaction (Myer et al., 1980; Myer and Kumar, 1984), but with distinct kinetic parameters, the first-order reduction constants and the protein-ascorbate stability constants. It has been concluded that the functional-conformational differences between the two CT-cytochromes are not operational to any significant extent in the reduction reaction with ascorbate. The methionine-80-sulfur-iron linkage of the protein is not a crucial requirement for the ascorbate reduction of the protein. The mechanism of the reaction in the main is also insensitive to the replacement of Met-80-S from heme coordination and/or the associated conformational-oxidoreduction properties of the protein. Of the two aspects of the reaction, the efficiency of the electron-transfer reaction and the stability of the ascorbate dianion-protein complex, the former is dependent on the integrity of the structural-conformational state of the molecule.     

Study of the gametocytocidal/sporontocidal action of qinghaosu (artemisinin) by electron microscopy

The gametocytocidal efficacy of artemisinin (qinghaosu) was evaluated and scanning electron microscopical evidence is given for gametocytocidal action of a single 5-10-mg/kg dose of artemisinin against simian malarial parasite (Plasmodium cynomolgi B). No sporontocidal effect of artemisinin was observed.