Kinetic studies on the reduction of metmyoglobins by ascorbic acid

The kinetics of the reduction of metmyoglobins by ascorbic acid (H2A) were studied under a nitrogen atmosphere at 25 degrees C, at an ionic strength of 0.30 M (NaCl), and between pH 7.18 and 8.09. Neither Tris-HCl nor phosphate buffers had any effect on the reduction of metmyoglobin. Imidazol and 1-methylimidazol accelerated this reaction, but N3- and CN- ions inhibited it. It is concluded that the reduction of imidazolmetmyoglobin or 1-methylimidazolmetmyoglobin is faster than that of aquametmyoglobin and that neither azidometmyoglobin nor cyanometmyoglobin can be reduced by ascorbate under the present experimental conditions. The second-order rate constants were determined for the reductions of aqua-, imidazol-, and 1-methylimidazolmetmyoglobin by ascorbate (HA- and A2-). The higher reactivity of imidazolmetmyoglobin with ascorbate may be due to the easy transfer of an electron of ascorbate to partially exposed imidazol or porphyrin ring because of expansion of the heme pocket induced by the coordination of imidazol.

[A double blind clinical trial of cefamandole and cefmetazole in complicated urinary tract infections]

We conducted a randomized double blind comparison of cefamandole (CMD) and cefmetazole (CMZ) in the treatment of 193 patients with complicated urinary tract infections. The patients received 1 gram of CMD or CMZ twice a day intravenously by drip infusion over 1 hour for 5 days. Pretreatment urinary leukocyte counts and urinary bacterial counts were at least 5 cells/hpf and 10(4) bacteria/ml, respectively. Each patient was randomly allocated either to CMD or CMZ group. There were 93 patients in CMD group and 100 patients in CMZ group. Clinical efficacy was evaluated based on the effect of treatment on bacteriuria and pyuria according to the criteria set by the UTI Committee, Japan. The response to CMD treatment was excellent in 18 cases (19.4%), moderate in 38 cases (40.9%) and poor in 37 cases (39.8%) with an overall effectiveness of 60.2%, whereas the response to CMZ was excellent in 19 cases (19.0%), moderate in 40 cases (40.0%) and poor in 41 cases (41.0%) with an overall effectiveness of 59.0%. No statistical significant difference was found between 2 treatment groups. Comparison of the bacteriological response between 2 groups showed that the eradication rate for strains of Gram-positive cocci were significantly higher in those patients treated with CMD. Gram-negative rods were eradicated from 68.4% of cases treated with CMD, and 78.0% of those with CMZ, but the difference was not significant. Adverse reactions were observed in 3 patients receiving CMD 1 case each of diarrhea, eruption and epigastric pain. Abnormality in laboratory tests was found in 6 patients in each treatment group. The results indicate that CMD is effective, safe and useful in the treatment of patients with complicated urinary tract infections, and its efficacy, safety and usefulness are comparable with those of CMZ.