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Biomedical subjects

T Takemoto

Publications and source records attributed to T Takemoto.

At least 163 records · Page 9Linked to original sources
PubMed1984

6-Tridecylresorcylic acid, a novel ATPase inhibitor that blocks the contractile apparatus of skeletal muscle proteins.

6-Tridecylresorcylic acid (TRA) isolated from a primula Lysimachia japonica Thunb. inhibited contraction of myofibrils, superprecipitation of myosin B, and ATPase activities of myosin and actomyosin prepared from rabbit skeletal muscle in a dose-dependent manner. The IC50 values in molarity of TRA were as follows: myosin (K+,EDTA)-ATPase, 3.5 X 10(-6); myosin Ca2+-ATPase, 3.5 X 10(-5); and actomyosin Mg2+-ATPase, 1.6 X 10(-5). The inhibition of ATPase activity of myofibrils by TRA was virtually reversed by washing with the fresh saline solution. Kinetic analysis of inhibitory effects of TRA suggests that the inhibition of (K+,EDTA)-ATPase activity of myosin or subfragment-1 is parabolic noncompetitive. TRA had no effect on alkaline phosphatase and choline acetyltransferase activities. TRA may provide a useful chemical tool for the study of the molecular mechanisms of actin-myosin contractile systems.

Actomyosin↗
PubMed1984

Effects of alpha-kainic acid, domoic acid and their derivatives on a molluscan giant neuron sensitive to beta-hydroxy-L-glutamic acid.

No identifiable giant neuron of an African giant snail (Achatina fulica Férussac) was found to be sensitive to L-glutamic acid (L-Glu). However, some of them, including the RAPN (right anterior pallial neuron), were sensitive to beta-hydroxy-L-glutamic acid (L-BHGA). The effects on RAPN of alpha-kainic acid (alpha-KA), domoic acid (DMA) and their derivatives, which are structurally related to L-Glu and L-BHGA, were examined in order to elucidate the chemical structures necessary to produce the effects under study. Erythro- and threo-L-BHGA showed similar excitatory effects on RAPN (the minimal effective concentration (M.E.C.): 10(-4)M). alpha-KA, alpha-KA methylketone and DMA also showed marked excitatory effects on the same neuron (M.E.C.: 3 X 10(-5)-10(-4)M). The two derivatives of alpha-KA, (2S, 3S, 4S)-2-carboxy-4-(1-methyl-5(R)-hydroxymethyl-l(Z),3(Z)-hexadienyl) pyrrolidine-3-acetic acid and (2S,3S,4S)-2-carboxy-4-(1-methyl-5(R)-hydroxymethyl-1(Z),3(E)-hexadie nyl) pyrrolidine-3-acetic acid, also had excitatory effects (M.E.C.: about 3 X 10(-4)M) which were somewhat less potent than those of L-BHGA, alpha-KA etc. However, alpha-allo-KA, alpha-allo-KA methylketone and dihydro-alpha-KA even at a high concentration of 4.7 X 10(-4)M, had no effect on RAPN. From the results obtained, it appears likely that the seven excitatory compounds mentioned above act on the common receptors of the RAPN neuromembrane, due to similarities in their structures and in the type of excitation caused by these compounds.

Animals↗
PubMed1984

New development of peroral cholangioscopy--evaluation of double-angle, oblique viewing cholangioscope.

Seven years have passed since the first report on peroral cholangioscopy by Takekoshi and Takagi (1) in Japan. Recently, several types of peroral cholangioscope with a forceps channel have been made for this treatment. However, the success rate of insertion of these instruments into the common bile duct was less than 50%. Therefore, in cooperation with Fuji-Photo-Optical Co. Ltd., we have made a new scope with the aim of facilitating insertion into the bile duct. Using this new scope, called a double-angle, oblique viewing cholangioscope, we obtain good orientation in the duodenum in en-face view and close inspection of the duodenal papilla, which makes possible easier insertion into the common bile duct. This new scope proved useful in basket removal of bile duct stone, or differential diagnosis between stones and carcinoma of the biliary tract.

Adult↗
PubMed1984

Clinical usefulness of ranitidine in giant gastric ulcer.

We define "giant" gastric ulcer as a chronic gastric ulcer, with a diameter greater than or equal to 3 cm. Treatment of inpatients with several conventional antiulcer agents resulted in significantly lower healing rates in giant gastric ulcer than in "large" (greater than 15 and less than 30 mm diameter) or "medium" (greater than 5 and less than or equal to 15 mm diameter) ulcers. In 48 patients with giant gastric ulcers treated with ranitidine, cumulative endoscopic healing rates were: 0% after 2 weeks, 16.7% after 4 weeks, 50.0% after 6 weeks, 77.1% after 8 weeks, 85.4% after 10 weeks, and 87.5% after 12 weeks of treatment. Corresponding healing rates were determined for the control group, which included patients treated with various conventional antiulcer agents. Comparison of these results revealed that from the fourth week of treatment onward, healing rates of the ranitidine group were significantly higher than those of the control group. There was little difference in the cumulative healing rates in the ranitidine group. From these results, ranitidine is considered to be useful in the treatment of giant gastric ulcer.

Adult↗
PubMed1984

Laparoscopic ultrasonography. Diagnosis of liver and pancreatic cancer.

We tested two kinds of laparoscopic ultrasonography having a 3.5 MHz and a 5.0 MHz, linear assay, generated into 45-mm-long and 13-mm-wide laparoscopic tip. Twenty studies were performed in 6 patients with HCC, 2 patients with pancreatic cancer and others. It is clearly demonstrated that this apparatus provides sufficient resolution real-time ultrasound visualization of a target organ on which ultrasonic probe is placed under direct vision.

Carcinoma, Hepatocellular↗
PubMed1984

[Autofluorescence of gastric cancer--study by flow cytometry].

Autofluorescence from cancer cells and non-cancerous cells of the stomach was measured by flow cytometry. The number of cells with fluorescence and its intensity was higher in cancer than in the surrounding mucosa. Preliminary results suggest that, if fluorescence emission from non-cellular substances is eliminated, measurement of fluorescence excited by laser illumination would permit earlier detection of gastric cancer.

Aged↗
PubMed1984

Curious manifestations in cavernous hemangioma of the liver.

We report a cavernous hemangioma of the liver with some curious findings. Angiography showed a hypervascular lesion and the arterioportal shunt which commonly is regarded as a pathognomonic sign of malignancy. Laparoscopy showed a well-defined, reddish-purple elevated lesion with a central umbilication. As the patient was a painter and dealing with vinyl chloride monomer, we suspected the possibility of hemangiosarcoma. The lesion proved to be a cavernous hemangioma with central fibrous replacement probably in consequence of thrombosis of some cavernous spaces.

Angiography↗