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Biomedical subjects

K Tsuji

Publications and source records attributed to K Tsuji.

At least 613 records · Page 34Linked to original sources
PubMed1987

Comparison of antinicotinic activity by neosurugatoxin and the structurally related compounds.

Neosurugatoxin (NSTX) which contains two sugars (myoinositol and xylopyranose) and bromine in the chemical structure, has been shown previously to be a selective antagonist of nicotinic receptors in guinea pig ileum and in murine brain. To study the role of sugar moiety and bromine in the antinicotinic activity by NSTX, we have examined the action of NSTX (compound I) and the structurally related compounds (compound II, III and IV) on the nicotine-induced contraction of guinea pig isolated ileum and on specific [3H]nicotine binding in rat forebrain membranes. Among four compounds examined, compound I was the most potent in inhibiting the nicotine-induced contraction of guinea pig isolated ileum (pA2 = 9.1 +/- 0.1, pD2' = 8.0 +/- 0.1) and also in inhibiting specific [3H]nicotine binding in rat forebrain (IC50 = 83 +/- 9 9 nM). Compared to compound I, compound II and III which are devoid of one and two sugars, respectively, in the chemical structure of compound I were 2 or 3 times less potent in the antinicotinic activity in both tissues, and compound IV which lacks bromine in addition to two sugars was two orders of magnitude less potent. Thus, the present study demonstrates that bromine rather than sugar moiety in the chemical structure of compound I (NSTX) is an important determinate of its high affinity for nicotinic receptors.

Animals↗
PubMed1987

Recovery of endotoxin from human plasma by acid oxidative treatments as monitored by an automated microtiter plate-chromogenic substrate Limulus amebocyte lysate (LAL) assay method.

Methods to detect endotoxin in human plasma for LAL testing have been developed by use of a perchloric acid (PCA) or a trifluoroacetic acid (TFA) treatment. These acid oxidative treatments eliminate interferences present in plasma. The mode of action of the acids for the elimination of the interferences is indicated to be by their oxidative actions. The treated plasma is assayed by use of an automated microtiter plate-chromogenic substrate LAL assay method employing a modified Cetus Pro/Pette EXPRESS system. The automated system assays 96 samples in approximately 22 minutes. Assay sensitivity of the automated Pro/Pette system is approximately 0.01 endotoxin units (EU) per ml with a linear range from 0.03 to 0.14 EU/ml. The relative standard deviation (RSD) of the assay system is approximately 6%. The improved precision of the LAL assay by the automated system has been attributed to its fast speed (2 minutes) in dispensing the unstable LAL reagent to all 96 samples in one assay block. The total operation, including the acid oxidative treatments and the 96 sample LAL assay, takes approximately 45 minutes. The recovery of spiked endotoxin from plasma ranged from 75 to approximately 100% by adding 0.4 ml of either 0.1-0.2 N PCA or 0.2-0.35 N TFA to 0.2 ml plasma and reacting for 15 minutes at 37 degrees C. The standard deviation of the assay is approximately 0.1 EU/ml plasma. The method has been proven to be rugged, simple, rapid, and cost effective thus would be suitable for clinical application.

Autoanalysis↗
PubMed1987

[Measurement of microsomal function in hepatectomized rat].

Trimethadione (TMO) is exclusively metabolized to dimethadione (DMO) by cytochrome P-450 dependent mono-oxygenase in liver microsomes. We have chosen TMO as an indicator compound for estimating the microsomal function of the liver. TMO tolerance test was performed in the CCl4 intoxicated injury or 68% partial-hepatectomized rats. Serum DMO/TMO ratios in 2 hours following oral administration of TMO in these rats in vivo were well correlated with changes in content of hepatic cytochrome P-450 and activity of TMO N-demethylase in vitro. TMO tolerance test could also determine quantitatively the changes of the functional capacity of the liver in the 68% partial hepatectomy. These results suggest that TMO tolerance test is a useful tool for the surgical indication in the hepatectomy.

Animals↗
PubMed1986

Effects of oral glucose administration on preproinsulin mRNA in rats in vivo.

An experiment was performed to examine whether the acute increase in insulin release induced by oral glucose ingestion is associated with alterations in pancreatic preproinsulin mRNA (PImRNA) levels. Rats either fed ad libitum or after overnight fast were used. Fasted rats were administered glucose orally in a conscious, unrestrained state. Pancreatic RNA was extracted and the relative level of PImRNA was determined by dot blot analysis with a cloned rat preproinsulin I cDNA probe. In fasted animals PImRNA levels decreased compared with those of fed animals and showed no significant changes after acute glucose administration, while blood glucose and plasma insulin increased rapidly to maximum values at 15 min after glucose administration. Although the transcription rate was not directly measured in this experiment, it is possible that the rapid increase in insulin release from the beta cell under physiological conditions is controlled by post-transcriptional regulations.

Animals↗
PubMed1986

Derivatization of primary amines by 2-naphthalenesulfonyl chloride for high-performance liquid chromatographic assay of neomycin sulfate.

A normal phase high-performance liquid chromatographic (HPLC) method has been developed for the assay of neomycin sulfate. The method involves pre-column derivatization with 2-naphthalenesulfonyl chloride (NSCl) followed by extraction in chloroform and chromatography using a normal phase silica column with detection at 254 nm. The standard curve for the HPLC assay of neomycin sulfate is linear with a correlation coefficient of 0.9996 over the range of 0.02 to 0.4 mg/ml. Neomycins B, and C, and neamine can be separated and quantified isocratically with relative standard deviations of 0.92% and 1.4% for neomycin (B + 1/2C) and neamine, respectively. Prednisolone is used as an internal standard to aid in quantification. Mass spectrometric data confirms that neomycin is derivatized at all the six primary amines on the neomycin molecule. Eight lots of neomycin sulfate were used to compare the HPLC [NSCl and 1-fluoro-2,4-dinitrobenzene (DNFB)], gas-liquid chromatographic and microbiological assay methods. The average results of the NSCl-HPLC method fell between those of the microbiological and DNFB-HPLC methods. Also, good correlation of the neomycin C contents in neomycin were obtained between the NSCl-HPLC and DNFB-HPLC methods.

Amines↗