From the basic studies on sensitivity test of anticancer drug using diffusion chamber, the following results were obtained.
1) The growth of ascites tumor cell in diffusion chamber was influenced by the difference of target cell count previously enclosed in.
2) The growth rate of ascites tumor cell and the variance of ascites tumor cell count in diffusion chambers inserted in abdominal cavity were both larger than in subcutan.
3) Decrease and increase in target cell count in diffusion chambers were regarded as the indicator and the result was obtained that the diffusion chamber technique was useful as the sensitivity test of anticancer drug for tumor cell.

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In order to establish the procedure for evaluating the effect of chemotherapeutic agents against the infection with Pseudomonas aeruginosa, a selection of suitable strain was made among 60 strains by determining their virulence in mice and drug sensitivities. Various experiments were made in the several condition and experimental error and reproducibility of data were discussed. It was found that therapeutic effect varied according to variation of inoculum size of the test strain, and difference of administration route of the agents. By way of the procedure to be set for evaluating the effect of chemotherapeutic agents in vivo, ED₅₀ of various chemotherapeutic agents was obtained at 19.0mg/ kg in kanamycin, 1.8mg/kg in polymyxin B, 18.0mg/kg in colistin and 2.1mg/kg in gentamicin respectively.

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A paper disc thin-layer plate microassay method for determination of antibiotic concentrations in the body fluid, using minute amounts of test sample preparable for the assay at bedside, was evaluated as to its usefulness and reproducibility of the results thereof.
1) It was found essential to allow blood samples be absorbed in constantly the same quantities by assay discs, since the diameters of inhibition zones produced were affected by the amount of a blood sample with which the filter paper discs were impregnated.
2) When phosphate buffers at various pH, a serum and a whole blood were used in the reference assay series, it was found that the results of assay for erythromycin and streptomycin were influenced by the pH of phosphate buffer, and the results of assay for streptomycin by the serum and whole blood. It followed that it was important to use the same ones as the reference samples as much as practicable.
3) Effect of various preserving conditions on the results of assay with heparinized whole blood samples and with (non-heparinized) whole blood samples obtained immediately prior to assay was studied. We observed practically no influence due to the sample difference upon the assay results for erythromycin, tetracycline, benzyl-penicillin and streptomycin. The findings indicated practicability of the use of heparinized whole blood as the standard sample.
4) With a view to equalization of the amounts of whole blood samples with which filter paper discs saturated, the technique for preparation of saturated assay discs was standardized as follows : Allow one end of a disc to touch the whole blood sample and wait until the whole blood soak into entire disc; then remove excess blood from the disc with a blotting paper pressed lightly on it; and use it in the assay. The amount of whole blood absorbed by the disc (8mm in diam.) was 37.65±2.34mg on the average immediately after the saturation and was 24.10±1.19mg after drying. In either case the coefficient of variation was not more than 10%.
5) The difference in whole blood content between the moist disc (immediately after saturation) and dried disc did affect the diameters of inhibition zones but it was found to be abolished when the discs were allowed for prediffusion for not less than six hours before incubation. However, when allowed for prediffusion for more than twelve hours, discs impregnated with low concentrations of chloramphenicol or benzyl-penicillin showed some reduction in the diameter of inhibition zones. Consequently, it was considered advisable to perform prediffusion for six to twelve hours, unless the chemotherapeutics to be assayed for were particularly poorly diffusible.
6) To assess the assay method as to its accuracy, ranges of experimental errors in tetracycline, benzyl-penicillin, and kanendomycin assays were determined. As a result, it was found that the range of experimental error was 78-133% (minimum) to 60-193% (maximum) when single assay plates were employed, and 86-118% (min.) to 75-146% (max.) when assays were carried out in triplicate, respectively.
7) The subject paper disc technique was applied to the thin-layer plate method using spores of B. subtilis PCI 219 as test organism. As a result, a linear relationship was confirmed to exist between the logarithmic value of drug concentration in whole blood sample and the diameter of inhibition zones in cases of assay with kanamycin, tetracycline, erythromycin, and chloramphenicol.
8) In practice, levels of the active concentration of chloramphenicol in whole blood were determined by the said assay method with reasonable accuracy in individuals receiving the agent by oral route.

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1, 2-Bis [5 (or 6) -methoxy-2-benzimidazolyl] 1, 2-ethanediol (BMBID) at a concentration of 35. 4mcg/ ml (10^-4M) clearly inhibited the formation of infectious RNA of poliovirus and the incorporation of ¹⁴C-uridine into poliovirus RNA. Marked reduction of virus yield and inhibition of plaque formation could be demonstrated when the infectious RNA was infected on HeLa S₃ cells in the presence of BMBID, but BMBID did not have any direct inactivation effect on infectious RNA of poliovirus. It is thought therefore that the inhibitory effect of poliovirus growth by BMBID may be due to an inhibition of viral RNA replication.

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When ampicillin was injected to healthy human adults and experimental animals, an unknown substance with antimicrobial activity, besides ampicillin, was excreted in urine. The substance was also formed by incubation of ampicillin with urine, serum or tissue homogenate of rats. Materials which were present in the homogenates and reacted with ampicillin were small molecules and heat-stable. The antimicrobial activity of the metabolite against some gram-negative bacteria were weaker than that of ampicillin. The metabolite concentration in serum and urine of healthy adult receiving ampicillin intramuscularly was very lower than ampicillin concentration.

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Cycloheptimidazolon is a compound similar to benzimidazolon but with seven-members ring instead of benzene ring. One of these compounds, 1 (2-dimethylaminothyl) cycloheptimidazole-2 (1 H) -one was injected intraperitoneally with ³²P to the rats bearing regenerating liver. In those rats, DNA synthesis was observed 2 hours earlier than the control rats. Thymidine kinase extracted from the same regenerating liver was found markedly enhanced. On the contrary, when rat ascitic hepatoma (AH 130) was incubated in vitro for 60 minutes with ³H-thymidine and 8 mM of cycloheptimidazolon derivatives, remarkable inhibition was observed. In these cases, although an appreciable inhibition was not found in thymidine kinase activity by these compounds, DNA polymerase extracted from hepatoma cells was suppressed by in vitro addition of cycloheptimidazolon derivatives. Thus, these compounds showed a selective inhibition on DNA synthesis in cancer cells but not on DNA replication in regenerating liver.

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On nafcillin, a new antibiotic in Japan, we performed laboratory and clinical studies in the orthopedic infectious disease.
With 53 strains of Staph. aureus isolated from the patients of osteomyelitis, the sensitivities to nafcillin (NF-PC), MCI-PC and PC-G were measured by the plate dilution method.
The MIC values of NF-PC were 0.10 to 1.59 mcg/ml (peak 0.39 mcg/ml) and NF-PC was sensible to PC-G resistant strains.
A 500 mg intramuscular dose developed a peak serum level at 1 hr. (7.9 mcg/mg) and a peak synovial fluid level at 4 hr. (1.90 mcg/ml).
Ten cases of chronic osteomyelitis and 3 cases of subcutaneous infection were treated with NF-PC.
The results were excellent in 3 cases, good in 7 cases and no effect in 3 cases that were chronic osteomyelitis.
Side effect was not found in all cases.

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Rolitetracycline (PRM-TC) was used by this author in local wounds after many kinds of orthopaedic surgeries. It was applied by injection into the wounds soon after operations while the patients were still under anesthesia, and every case has already received the injection of the new drugs before surgery. There were 87 cases whose ages ranged from 3 to 83.
There were sufficiently good results with minimum doses of the new antibiotics in pre- and post-operative administrations ; for example, the average doses of the new drugs were 1.4 ampoules by injection and the other antibiotics were administered per os only 4.8 days in addition.
No serious side-effects were found among all of the 87 cases, and no symptoms of post-operative infection were observed except one patient who was suffering from osteomyelitis. In particular, 15 cases had no antibiotics except local injection of PRM-TC.
At the aseptic operation, and the like the antibiotics were injected 90 minutes before surgery, when the blood concentration reached its peak, and just at that time operations could be performed. In addition, as soon as the operation was finished PRM-TC was injected locally into the wound, and the use of the new antibiotics was not needed thereafter. PRM-TC is a highly commendable drug, if used for the above purpose with the method above mentioned.

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A study on in vitro antibacterial activities of nitroimidazole thiadiazole, a new synthetic antibiotic, was carried out using 11 species of bacteria. As controls, 10 kinds of known antibiotics were used.
This drug completely inhibited, at the concentration of less than 0.39 to 12.5 mcg/ml, the growth of the following bacteria. Enterobacteriaceae ; Shigella, Salmonella, Escherichia coli, Klebsiella. Gramnegative bacteria ; Vibrio cholera, V. parahemolyticus. Gram-positive cocci ; Staphylococcus aureus, group A Streptococcus. Anaerobic bacteria ; Clostridium welchii. The MIC of this drug against Pseudomonas and Proteus was 100 mcg/ml. From the antibacterial spectrum of this drug, it was considered that the antibacterial activities of nitroimidazole thiadiazole were equivalent to those of known antibiotics used as controls. Of the known antibiotics compared with this drug, tetracycline revealed the closest antibacterial spectrum to this drug. Against Shigella and group A Streptococcus, antibacterial activities of this drug were superior to those of tetracycline. Against other bacteria, antibacterial activities of these two drugs were the same.

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Stability of H.infiuenzae in various conditions and the effect of various antibiotics on spheroplast transformation of H.influenzae in vitro were investigated by using a medium containing 5% digested blood of rabbits instead of ordinary chocolate agar medium for H. influenzae. The results were as follows.
1) The growth of H. infiuenzae in this medium was excellent and transparency of the medium was most favourable for the microscopic examination.
2) H. infiuenzae was most stable under the condition of freezing and drying and it fairly resisted to the freezing at-20C. Because of the readiness, however, the latter treatment was recommended for the storage of the strains.
3) Among the antibiotics tested for the inhibition of the growth of H. influenzae strains, only the PC group antibiotics showed higher values of MIC/MAC ratio with certain strains.
The PC group antibiotics, when the MIC/MAC ratio was over 8, frequently produced the filamentous and spheroplast forms of H. infiuenzae.
Accordingly, as for the PC group antibiotics, the MIC/MAC ratio was thought to be a good indicative of the spheroplast transformation of H. influenzae.

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