Biomedical subjects
Publications and source records attributed to K Shibata.
Mycoplasma salivarium produced citrulline, ammonia, and ATP from N-benzoylglycyl-L-arginine. The activity was inhibited by EDTA and was therefore concluded to be due to an arginine-specific carboxypeptidase. The activity was also found to exist in M. orale, M. buccale, M. faucium, and M. hominis.
Phosphatase activity was found to be applicable as a criterion for the differentiation of Mycoplasma salivarium and Mycoplasma orale, predominant constituents of oral mycoplasmal flora. Therefore, a simple procedure for the phosphatase activity assay was established as a screening test for the differentiation of oral mycoplasmas.
In an animal model of human rickets developed by giving a short-term administration of large doses of EHDP to young rats, concomitant administration of [Asu1,7]eel calcitonin (CT) with EHDP resulted in the promotion of calcification in growth cartilage. In an attempt to clarify the mechanisms related to the accelerated calcification due to CT, the effects of diltiazem, a calcium antagonist, were studied. Diltiazem suppressed, in a dose-dependent manner, the accelerated calcification due to CT in the growth cartilage, as determined by findings on the soft X-ray photos, contact microradiograph and light microscopic histology of the proximal region of the tibia. This suppression was only evident when diltiazem and CT were given concomitantly. If it is assumed that diltiazem inhibits the entry of calcium ion into the cells of growth cartilage, in the same manner as seen in case of smooth muscle and myocardial cells, then our results indicate that intracellular concentrations of calcium might play an important role in the occurrence of accelerated calcification due to CT.
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Several halogenated and other related derivatives of herbimycin A have been synthesized and evaluated in vivo for their activities against Ehrlich ascites carcinoma. Some of these derivatives show higher activities than herbimycin A. Among them the derivatives modified at the 4, 5, 6, and 7-positions of the ansa chain showed particularly high activities.
Two patients with advanced germ cell tumor who entered complete remission following intensive combination chemotherapy, radiation therapy and surgical intervention are reported. A 28-year-old businessman presented with abdominal pain and masses associated with an elevated HCG level for which he underwent exploratory laparotomy. Large retroperitoneal masses were found and microscopical examination of the masses were revealed seminoma. Three courses of combination chemotherapy consisting of CDDP, VLB and PEP were given to the patient followed by radiation therapy to the parailiac, paraaortic, mediastinal and supraclavicular lymph nodes with boost irradiation to the paraaortic lymph nodes where the large masses were located. The other patient was a 21-year-old student who developed sharp precordial chest pain which proved to be due to a large mediastinal mass accompanied by an elevated AFP level. He was treated with radiation therapy to the mediastinum, surgical resection and combination chemotherapy. However, he showed recurrence in the lungs associated with rising AFP levels, and was given a salvage chemotherapy consisting of 3 courses of CDDP, ADR, PEP and Etoposide. Both patients were successfully treated with combined modalities of treatment including intensive chemotherapy and have been off therapy without recurrence for over 12 and 4 months, respectively.
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Glomerular injury was produced in mice after a single LD50 intravenous dose of purified 100-pace snake venom (Agkistrodon acutus). Characteristic features in glomeruli where the venom was demonstrated immunohistochemically included cystic lesions of the capillary tufts, thrombosis, subsequent proliferative and sclerotic changes, and crescent formation. Venom was recognized immunohistochemically in the glomerular endothelium, visceral basement membrane, mesangium, epithelium, and Bowman's capsule. Venom transfer across the basement membrane or into cells required less than 2 hours. Within this period mesangiolysis occurred due to the protease activity of the venom. Cystic lesions with fibrin thrombi then developed, which were replaced by proliferative and sclerotic changes after 3 days. Crescent formation began within 48 hours and was completed within a few days. Microangiography revealed hemodynamic changes in the intrarenal vasculature after venom treatment. Immune complex deposition was not found in any tissue. The study demonstrates the moderately constant potency (LD50) of Agkistron acutus venom, and documents it as a useful tool for quantitative studies of renal lesions.
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Ischemic colitis following aortic reconstruction for abdominal aortic aneurysm was discussed. The low morbidity rate of postoperative abdominal symptom was recognized significantly when meandering mesenteric artery (MMA) was shown clearly in angiography before surgery. When inferior mesenteric artery (IMA) was patent before surgery, furthermore when IMA was not reconstructed, it is necessary for preventing postoperative ischemic colitis that mean IMA/systemic pressure ratio is above 0.5 or 0.6.