Toshio Kaneko
University of Tokyo
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Featured researches published by Toshio Kaneko.
Metabolism-clinical and Experimental | 1973
Toshio Kaneko; Shiro Saito; Hiroshi Oka; Toshitsugu Oda; Noboru Yanaihara
Abstract Synthetic LH-RH (1 μg/ml) in vitro increased cyclic AMP concentration of rat anterior pituitary within 1 min and HL release into the medium after 15 min incubation. The minimum effective dose of synthetic LH-RH on cyclic AMP formation was 10 ng/ml. Data obtained using synthetic analogs of LH-RH indicated that the N-terminal amino acid and the C-terminal carboamide group of synthetic LH-RH are necessary for biologic activity.
Biochemical and Biophysical Research Communications | 1974
Toshio Kaneko; Hiroshi Oka; Masahide Munemura; Seiji Suzuki; Hiroko Yasuda; Toshitsugu Oda; Noboru Yanaihara
Abstract Synthetic somatostatin stimulated cyclic GMP accumulation with dose dependency (10 ng/ml – 10 μg/ml in a dose examined) in rat anterior pituitary gland in vitro. The stimulation of cyclic GMP levels in the gland was observed after 2 min incubation with somatostatin. Cyclic AMP production induced by TRH or PGE 1 was supressed by this GH release inhibiting factor, while cyclic GMP concentration in the gland was elevated. The present results seem to suggest that inhibitory effect on GH release by somatostatin in anterior pituitary gland is mediated through change in concentration of cyclic AMP and cyclic GMP in the target cells.
Metabolism-clinical and Experimental | 1978
Akio Kaneto; Toshio Kaneko; Seishi Nakaya; Hiroshi Kajinuma; Kinori Kosaka
Synthetic bombesin was infused at a dose of 20 pmoles/kg/min for 10 min into the cranial pancreaticoduodenal artery of anesthetized dogs. Plasma immunoreactive glucagon concentrations in the cranial pancreaticoduodenal vein as well as in the femoral artery were concurrently and slowly elevated. However, the net release of glucagon from the pancreas did not increase significantly during infusion of bombesin. Plasma immunoreactive insulin concentrations in the pancreatic vein were transiently raised, and a delayed rise was noted in arterial plasma IRI. Net release of insulin was significantly augmented during infusion of the tetradecapeptide. Plasma glucose levels did not change after bombesin. These results indicate that the gastrointestinal tetradecapeptide may stimulate secretion of both insulin and gut glucagonlike immunoreactivity in the dog.
Biochemical and Biophysical Research Communications | 1973
Noboru Yanaihara; Tadashi Hashimoto; Chizuko Yanaihara; K. Tsuji; Y. Kenmochi; F. Ashizawa; Toshio Kaneko; Hiroshi Oka; Sachiko Saito; Akira Arimura; Andrew V. Schally
Abstract Syntheses by the conventional methods as well as the chemical, physical and biological properties are described of the following analogs of the LH-releasing hormone (LH-RH): [Leu3]-LH-RH, [Phe3]-LH-RH, [Trp2] [His3]-LH-RH, Des-Trp3-LH-RH, Des-His2-[Phe5]-LH-RH, [Ala4]-LH-RH, [Phe5]-LH-RH and [Ala4] [Phe5]-LH-RH. In vivo assays showed that [Leu3]-LH-RH did not release LH in doses as high as 5 – 25 μg, having less than 0.0008% of LH-RH activity, while [Phe3]-LH-RH had 0.43% of the LH-RH activity of natural LH-RH. The LH-RH activities of [Trp2] [His3]-LH-RH, Des-Trp3-LH-RH and Des-His2-[Phe5]-LH-RH were extremely low. On the other hand, [Ala4]-LH-RH, [Phe5]-LH-RH and [Ala4] [Phe5]-LH-RH had significant LH-RH activity. The structure-activity relationship of LH-RH is discussed on the basis of these findings.
Metabolism-clinical and Experimental | 1977
Akio Kaneto; Toshio Kaneko; Hiroshi Kajinuma; Kinori Kosaka
Synthetic vasoactive intestinal polypeptide (VIP) was infused at a dose of 50 ng/kg/min for 10 min into the cranial pancreaticoduodenal artery in anesthetized dogs. Both mean blood flow and plasma glucagon concentration in the cranial pancreaticoduodenal vein were significantly enhanced during the infusion, indicating a great augmentation in glucagon output. The pancreatic venous plasma concentration of insulin was not significantly raised, but its output increased during the infusion, again due to the increase in plasma flow. Plasma concentration of glucagon in the femoral artery was not significantly augmented, whereas that of insulin was enhanced during VIP infusion. Mean arterial plasma glucose levels rose gradually during the infusion. Intrapancreatic pretreatment with propranolol failed to exert any significant inhibiting effect upon the VIP-induced enhancement in plasma glucose, pancreatic venous blood flow, or bihormonal output. These results suggest that the vasoactive polypeptide of intestinal origin may regulate the function of the endocrine pancreas and that this effect may not be mediated mainly via the beta-adrenergic receptor system.
Biochemical and Biophysical Research Communications | 1973
Noboru Yanaihara; K. Tsuji; Chizuko Yanaihara; Tadashi Hashimoto; Toshio Kaneko; Hiroshi Oka; Akira Arimura; Andrew V. Schally
Syntheses and biological activities of analogs of luteinizing hormone-releasing hormone (LH-RH) substituted in position 1 or 2 are described. The syntheses of (Pro 1)-LH-RH (Orotic acid 1)-LH-RH (Glu 1)-LH-RH (Ser 2)-LH-RH (Leu 2)-LH-RH (Gln 2)-LH-RH and (Phe 2)-LH-RH are described. The LH-RH activity of each peptide was compared with that of natural LH-RH in vivo by stimulation of LH release in ovariectomized rats pretreated with estrogen and progesterone. (Glu 1)-LH-RH and (Phe 2)-LH-RH had LH-RH activity of 5.7% and 1.4% respectively while all the other analogs possessed extremely low activities. These results are discussed in reference to the structure-activity relationship for LH-RH.
Biochemical and Biophysical Research Communications | 1972
Noboru Yanaihara; Chizuko Yanaihara; Tadashi Hashimoto; Y. Kenmochi; Toshio Kaneko; Hiroshi Oka; Sachiko Saito; Andrew V. Schally; Akira Arimura
Abstract Syntheses by the conventional method are described of [Gln8]-LH-RH, [Leu8]-LH-RH and [Pro8] [Arg9]-LH-RH. These peptides were purified by column chromatography on CM-Sephadex and gelfiltration on Sephadex G-25 and proved to be homogeneous. The LH-RH and FSH-RH activities of these peptides were compared with those of natural LH-RH in vivo and in vitro . [Gln8]-LH-RH had significant LH- and FSH-RH activities, while [Leu8]-LH-RH and [Pro8] [Arg9]-LH-RH had lower activities.
Metabolism-clinical and Experimental | 1978
Akio Kaneto; Hiroshi Kajinuma; Toshio Kaneko; Kinori Kosaka
Synthetic cyclic somatostatin was infused into either the cranial pancreaticoduodenal artery or the femoral vein of anesthetized dogs with or without previous administration of phentolamine. Somatostatin infused into the pancreatic artery at a dose of 50 ng/kg/min for 10 min caused significant decreases in blood flow and plasma basal concentrations of both glucagon and insulin in the cranial pancreaticoduodenal vein, resulting in a profound decline of bihormonal output during the infusion. Arterial plasma glucose was not reduced during the administration of somatostatin in the pancreatic artery. These somatostatin-induced decreases failed to be eliminated by a 0.2 mg/kg injection of phentolamine into the femoral vein followed by a 9-min infusion of this alpha-adrenergic blocker (0.02 mg/kg/min) into the pancreatic artery immediately prior to the somatostatin administration. An inhibition of glucagon and insulin output and a fall of plasma glucose caused by somatostatin (1.7 microgram/min) infused into the femoral vein for 30 min also were not abolished by a prolonged and simultaneous infusion of phentolamine (0.2 mg/min) into the femoral vein over a period of 2 hr. These results indicate that alpha-adrenergic receptor mechanisms do not play a major role in the inhibition of islet glucagon and insulin secretion by somatostatin.
Archive | 1969
Toshio Kaneko; Hiroshi Oka; Toshitsugu Oda; Yawara Yoshitoshi
Recently there have been several reports that xylitol stimulates steroid synthesis (in vitro [1]) as well as reduction of methemoglobin in erythrocytes [2]. It has been assumed that these stimulations might be induced, at least in part, by altered pyridine nucleotide levels in each of the organ tissues. Actually, the conversion of xylitol to L- or D-xylulose within the cell is accompanied by the reduction of pyridine nucleotides. Therefore the effects of xylitol and other related compounds on the pyridine nucleotide levels have been studied in rat liver slices, and the results are presented in this paper.
Gastroenterologia Japonica | 1979
Toshikata Okayama; Fumiaki Koizumi; Hideo Watanabe; Toshio Kaneko; Hiroshi Oka; Akio Kaneto; Noboru Yanaihara; Scishi Nakaya; Zen Itoh; Ken Yamaguchi; Isamu Adachi; Fujio Zeze; Kaoru Abe; Toru Kameya; Saburo Arai; Haruko Sato; Chizuko Yanaihara; Mitsugi Sugiyama; Yozo Watanabe; Mitsuhiro Matsumura; Sciichiro Kishi; Hiroyoshi Mori; Hiroto Akiroshi; Kenji Shima; Ryoichi Tanaka; Tatsuo Matsuyama; Tetsuo Morishita; Masaharu Tsuchiya; Yasuyuki Arakawa; H. Nishikawa
The Ist presumptive evidence that gastrointestinal hormones influence growth is found in a number of studies describing the long term effects of antrectomy on the remaining oxyntic gland mucosa. And, it is reported that gastrin stimulates protein and DNA synthesis, this effect is specific to certain tissue of the digestive tract, and it is dependent of secretory phenomena. From this experiment, it is concluded that the effect of gastrin is mediated by cyclic GMP and in gastric atrophy, the responses of cyclic GMP and protein synthesis to gastrin is diminished.