The ras oncogene products (ras p2ls) are 21-KDa proteins with activities of GTP binding and hydrolysis. A number of proteins homologous to ras p21 have been discovered and collectively named small molecular weight GTP-binding proteins. These proteins undergo post-translational modification with isoprenoid residues attached to cysteine in their carboxyl terminal. With this modification, they attach to cellular membranes. The biochemical activities of these proteins, i.e., GTP hydrolysis and binding, are regulated by various regulatory factors such as GDP-GTP exchange proteins and GTP-aseactivating proteins, but little is known about the cellular functions and physiological pathways through which they regulate these functions. Botulinum C₃ ADP-ribosyltransferase, a 23-KDa exoenzyme secreted from certain strains of types C and D Clostridium botulinum, specifically ADP-ribosylates the rho family of these GTP-binding proteins. This ADP-ribosylation occurs at a specific asparagine residue in their putative effector domain, and presumably interferes with their interaction with a putative effector molecule downstream in signal transduction. C₃ exoenzyme, when incubated with or microinjected into cultured cells, ADP-ribosylates a rho gene product in the cells, and causes profound cell rounding with loss of adhesion plaques and collapse of stress fiber. Microinjection of an activated mutant of rho A protein, on the contrary, induced extensive adhesion and actin assembly in cultured cells. These results suggest that the rho family of proteins are involved in morphogenesis and motility of cells via assembly and disassembly of cytoskeletal systems, and botulinum ADP-ribosyltransferase is a useful tool for clarifying the molecular mechanism of these processes.

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The present study examined the pharmacokinetic and pharmacodynamic profiles of recombinant human erythropoietin (SNB-5001) in partially nephrectomized rats. The plasma level of SNB-5001 was measured by a 2-step enzyme immunoassay. The plasma disappearance curve after intravenous injection of SNB-5001 (50 U/kg) in these rats showed a biexponential pattern similar to that in non-treated rats, conforming to a two-compartment model. However, the total body clearance was reduced, the plasma half life was prolonged and the area under the concentration-time curve of SNB-5001 was increased by the partial nephrectomy. The distribution volumes of SNB-5001 were almost the same as those in non-treated rats. It is suggested that the kidney may contribute to the elimination of SNB-5001. Dose-dependent increases of reticulocytes, red blood cells, hemoglobin and hematocrits were observed after seven repetitive intravenous injections of SNB-5001 in both partially nephrectomized rats and non-treated rats. Hemopoietic responses were calculated by subtracting the initial values from the values after SNB-5001 injections of each hematological parameter (reticulocytes, red blood cells, hemoglobin and hematocrits). Hemopoietic responses in partially nephrectomized rats were apparently stronger than those in non-treated rats. These results suggest that the reduction of clearance by the partial nephrectomy may contribute to the hemopoietic responses, in addition to suggesting that the uremic conditions do not inhibit the effects of SNB-5001 in partially nephrectomized rats.

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In mice, SNB-5001 released reticulocytes dose-dependently. In rats, rabbits and dogs given the same doses of SNB-5001, each dose-response curve of hemopoiesis almost showed parallelism. SNB-5001 induced nearly the same extent of hemopoiesis in these animals. After the hemopoiesis caused by SNB-5001, reticulocytes decreased within a week in both rats and dogs, but numbers of red blood cells (RBC) were higher than each control group for over 2 weeks in rats and for over 3 weeks in dogs. In polycythemic rats given excessive doses (200 ?? 5000 U/kg) of SNB-5001, blood volume increased, but blood pressure did not change. In the renal anemic rats produced by partial nephrectomy, dose-related and cumulative hemopoiesis were observed in both groups given SNB-5001 with different administration schedules (once a day for a week or once a week for 3 weeks). In the phrebotomized rats, SNB-5001 accelerated the recovery from the anemia induced by phrebotomy when given in a large quantity (6 ml/rat) and prevented the progressive anemia induced by intermittent phlebotomies when given in a small quantity (1 ml/rat × 3). SNB-5001 also improved the anemia caused by chronic inflammation in rats. However, increases of hemoglobin and hematocrit were smaller than that of RBC. Those results were caused by impaired release of iron from the reticuloendothelial system.

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We studied the inhibitory effects of tranilast, an anti-allergic drug, on the human keloid tissues implanted into the dorsal skin of athymic nude mice and on the growth of keloid fibroblast in vitro. In the keloid tissue-implanted model, tranilast (50 ?? 200 mg/kg, p.o.) decreased the weight of the keloid tissue as triamcinolone (25 mg/kg, p.o.) did. Tranilast (200 mg/kg, p.o.) reduced the hydroxyproline content of implanted tissues. Tranilast (3 ?? 300 μM) also inhibited the collagen synthesis by keloid fibroblast in vitro. Only a high concentration of tranilast (300 μM) suppressed the glycosaminoglycan synthesis and cell proliferation of keloid fibroblasts. Moreover, tranilast scarcely affected the fibronectin production. Triamcinolone (10 μM) also inhibited glycosaminoglycan synthesis and cell proliferation. These results suggest that the inhibitory effect of tranilast on the keloid tissues is related to its inhibition of the collagen synthesis of fibroblasts. Tranilast would be useful as a therapeutic drug for the treatment of keloids.

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We studied the effect of tranilast on the growth of carrageenin-induced granulation and the increase in capillary permeability induced by inflammatory agents in rats. In the carrageenin-induced granulation model, tranilast (50 or 100 ?? 200 mg/kg, p.o.) decreased significantly and dose-dependently the weight and the hydroxyproline content of the granulation tissue. Tranilast, however, showed no effect on the healing day of locally wounded dorsal skin of rats. Triamcinolone (10 mg/kg, p.o.) also showed an inhibitory effect on the carrageenin-induced granulation model. Tranilast (50 ?? 400 mg/kg, p.o.) dosedependently inhibited the enhancement of capillary permeability induced by the Ca ionophore A23187, bradykinin and xanthine oxidase. Moreover, tranilast (30 and 300 μM) suppressed superoxide production induced by FMLP in human neutrophils, but did not act as a superoxide scavenger. Considering that hypertrophic scar and keloid are conditions characterized by abnormal cell proliferation and excessive collagen accumulation accompanied with itch and pain, these results suggest that tranilast is useful as a therapeutic drug for hypertrophic scars and keloids.

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To analyze the effects of naftidrofuryl oxalate (LS-121) on the central nervous system exposed to critical hypoxia, survival duration was employed as a parameter of the protective effects of the drug against hypoxia-induced death. In the control group (no drug administration), the electroencephalogram (EEG) was flattened promptly after changing to hypoxia from aerobic conditions, and it was impossible to recognize precisely what time the EEG disappeared because of vigorous body movements. Arterial blood pressure (BP) was clearly recognized, and rats never recovered after BP decreased to 0 mmHg, although the electrocardiogram (ECG) was still recorded. Thus, survival duration recognized by measuring the time from the onset of hypoxia to the time when BP became 0 mmHg was considered to be a good indicator. After LS-121 (10 mg/kg) administration, survival duration was significantly prolonged compared to the control. Combination therapy of LS-121 (25 mg/kg) and bifemelane hydrochloride (BI) (25 mg/kg) also revealed the prolongation of survival duration. Neither idebenone (10 mg/kg) nor nicergoline (10 mg/kg) showed significant changes in survival duration. These findings suggest that LS-121, either with or without BI, could improve cerebrovascular disorders induced by hypoxia.

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The gastric mucosal adhesiveness of Z-103 in rats with acetic acid ulcer was studied macroscopically, histologically, and biochemically. From macroscopical observations, when Z-103 was orally administered to an acetic acid ulcer model, there was adhesion of Zn to the normal mucosa as well as the ulcerous site under both the fasting condition and after feeding. It was also proven that the strength and duration of adhesiveness were increased dose-dependently under fasting conditions. In addition, histological localization of Zn was noted from the covering epithelial cell layer to the gastric lamina propria mucosae in the normal tissue and in the most superficial ulcerous layer and the granulous layer of the ulcerous site. Measurement of the gastric tissue Zn content after oral administration of 100 mg/kg of Zn showed that the Zn content was significantly increased for 6 hr at the normal site and for 24 hr at the ulcerous site. On the other hand, although ZnSO₄ and ZnSO₄+carnosine combination macroscopically produced generally the same level of adhesiveness as Z-103, when the gastric tissue Zn content for Z-103 and ZnSO₄ were compared, the Zn content of ZnSO₄ was lower than that for Z-103 at both the normal and ulcerous site. In summary, Z-103 shows a long-term adhesive and permeable action on the gastric mucosa in acetic acid ulcer rats, and it has a comparable high affinity at the ulcerous site.

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