Intra- and intermolecular interactions of the catalytic domains of human CD45 protein tyrosine phosphatase.

We have investigated protein-protein interaction between distinct domains of the human CD45 cytoplasmic region using a yeast two-hybrid system. Consequently, we have found that the spacer region between two tandem PTP domains specifically interacts with the membrane-distal PTP domain (D2). This interaction is mediated by a stretch of amino acid residues in the carboxyl-terminal half of the spacer region. Although the membrane proximal region does not directly interact with either of the two PTP domains, it appears to function in stabilizing the interaction between the spacer region and D2. We also demonstrate that the interaction between the spacer region and D2 might take place intramolecularly.

[Identification of the metabolites of an antiallergic agent, 1-(2-ethoxyethyl)-2-(hexahydro-4-methyl-1H-1,4-diazepine-1-yl)-1H- benzimidazole difumarate (KG-2413), in rats].

The urinary and biliary metabolites of a new antiallergic agent, 1-(2-ethoxyethyl)-2-(hexahydro-4-methyl-1H-1,4-diazepine-1-yl)-1H-b enzimidazole difumarate (KG-2413) in rats were identified by using a 14C-labelled drug and instrumental analyses, e.g., high performance liquid chromatography, gas chromatography (GC), 1H nuclear magnetic resonance, mass spectrometry (MS) and GC/MS. A slight amount of KG-2413 free base was detected only in the unconjugated fraction of urine. The main pathways of biotransformation of KG-2413 in rats were: (a) aromatic hydroxylation in the benzimidazole ring, (b) N-oxidation and N-demethylation in the 1,4-diazepine ring, (c) alpha-carbon oxidation (lactam formation) in the 1,4-diazepine ring (d) O-deethylation in the N-ethoxyethyl side chain. Regioselectivity was observed for aromatic hydroxylation, as only two of the four possible monohydroxylated metabolites could be detected. Furthermore, N-oxidation and lactam formation reactions were found to be regiospecific, that is, the former took place only at the position of 4-N atom and the latter at 5-C atom, respectively.

[Metabolism of lenampicillin hydrochloride. II. Metabolism of promoiety].

The in vitro and in vivo metabolism of promoiety in lenampicillin hydrochloride (LAPC) were investigated in rats and dogs. After incubation of LAPC with intestinal or liver preparations and blood of rat, diacetyl, acetoin and 2,3-butanediol were identified as metabolites of LAPC. The main metabolite in peripheral plasma was 2,3-butanediol after oral administration of LAPC in rats and dogs. On the other hand, high levels of acetoin were found out in portal plasma for early period after dosing of LAPC. These results suggested that the biotransformation of promoiety in LAPC to acetoin carried out mainly in intestinal tissues, but acetoin was converted to 2,3-butanediol in liver. Acetoin and 2,3-butanediol were also excreted in urine, but their urinary excretion were very low, and the combined excretion were accounting for about 9% of dose up to 48 hours after dosing in rats and less than 1% in dogs, respectively. The major metabolic pathways of promoiety in LAPC were postulated as below. (Formula: see text).

[Metabolism of lenampicillin hydrochloride. I. Metabolism of ampicillin structure].

Metabolism of lenampicillin hydrochloride (LAPC), especially ampicillin (ABPC) structure of LAPC, was investigated after oral administration in human, dogs and rats. The unchanged compound was not detected in blood and urine, furthermore in animal portal vein after oral administration of LAPC in human and 2 animals. Therefore, LAPC seemed to be rapidly hydrolyzed during the process of absorption. The intestinal absorption of LAPC was satisfactory in view of the urinary excretion of metabolites, accounting for 93% of dose in human, 74% in dogs and 55% in rats, respectively. It could be judged by the bioautograms and the correlation between bioassay and HPLC determination of ABPC that the active metabolite in blood or urine was only ABPC. The major urinary metabolites were ABPC, alpha-aminobenzylpenicilloic acid (ABPA) and 5S-penicilloic acid isomer (5S-ABPA) in human and 2 animals, but the differences were observed on the excretion ratio between human, dogs and rats. LAPC was stable in the intestinal contents, but liable to hydrolyze in the intestinal wall, blood and liver of rats. From the facts described above, it was concluded that LAPC was the efficient prodrug of ABPC in terms of the enhancement of absorption and decrease of side effects.

[Ifosfamide in the treatment of small cell carcinoma of the lung].

A total of 36 cases with small cell carcinoma of the lung were treated with Ifosfamide. Fourteen cases (38.9%) out of 36 cases showed good or marked clinical response, and 120 mg/kg of Ifosfamide was necessary as a minimum dose to obtain effective response. As side effects of Ifosfamide, gastrointestinal disturbance (66.7%), depilation (66.7%), leukopenia (38.9%) and hematuria (36.1%) were observed. Mean survival time (M.S.T.) was prolonged by using Ifosfamide, comparing with the groups treated by with other anticancer drugs. Ifosfamide, therefore, should be used for the treatment of small cell carcinoma of the lung.