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T Kawabata

Publications and source records attributed to T Kawabata.

At least 19 recordsLinked to original sources
PubMed1992

The role of the C-terminal region of rat brain natriuretic peptide in receptor selectivity.

Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) have different C-terminal tail structures compared with the rather conservative ring structures which consist of 17 amino acid residues. To examine the different effects of the tail structures of ANP and BNP on their interaction with receptors, we synthesized several peptide analogs and measured their biological actions in three different assay systems. Deletion of the C-terminal tail from rat BNP did not effect the vasorelaxation activity against rat aorta, but it promoted cGMP production in cultured rat aortic smooth muscle cells (RASMC). Deletion of the C-terminal tail from rat ANP diminished both vasorelaxant and cGMP producing activities. In a binding competition assay with RASMC and [125I]rat ANP-(1-28), the competition activities of both ANP and BNP were greatly reduced by C-terminal deletion. In addition, we obtained agonists with novel receptor selectivity.

Animals↗
PubMed1992

Increased plasma post-heparin diamine oxidase activity and plant sterol levels in streptozotocin diabetic rat.

Plasma post-heparin diamine oxidase (DAO) activity and plasma levels of plant sterols were examined in streptozotocin diabetic rats fed with chow containing plant sterols, to investigate the enzyme activity in relation to the morphological changes of small intestine as well as sterol absorption in the diabetic rats. Diabetic rats showed increased small intestinal mass and surface area compared with control rats. Plasma post-heparin DAO activity and plant sterol level were also increased more than 2.5-fold in the diabetic rats. Insulin treatment improved these abnormalities. Plasma DAO activity correlated to both the small intestinal hyperplastic change and plasma plant sterol levels. These results indicate that plasma post-heparin DAO activity may be used as a marker of intestinal hypertrophy as well as ability to absorb dietary sterols.

Amine Oxidase (Copper-Containing)↗
PubMed1992

A combination of the aldose reductase inhibitor, statil, and the prostaglandin E1 analogue, OP1206.alpha CD, completely improves sciatic motor nerve conduction velocity in streptozocin-induced chronically diabetic rats.

In view of the possible implication of multifactorial mechanisms in the pathogenesis of diabetic neuropathy, the aldose reductase inhibitor (ARI), Statil, which ameliorates abnormal sorbitol or myo-inositol metabolism in diabetic nerves, and the prostaglandin E1 (PGE1) analogue, OP1206.alpha CD (OP), which improves diabetic vascular derangements, were administered simultaneously for 2 months to streptozocin (STZ)-induced diabetic rats with 5 months' duration of diabetes, and the effects on sciatic motor nerve conduction velocity (MNCV), Na(+)-K(+)-adenosine triphosphatase (ATPase) activity, and morphology of myelinated nerve fibers (MNF) were compared with the effects of a monotherapy with OP. The combination regimen ameliorated abnormal nerve sorbitol and myo-inositol levels and normalized decreased MNCV and enzyme activity. In contrast, neither sorbitol nor myo-inositol metabolism was ameliorated, and only insufficient improvement of MNCV and morphology of MNF was obtained with a monotherapy with OP. In addition, the combination therapy reversed both a decrease in the percent of large MNF and an increase in the percent of small MNF in diabetic rats, whereas a monotherapy with OP reversed only a decrease in the percent of large MNF. The results might suggest that a multiple-drug therapy with different mechanisms of action has greater effects on diabetic neuropathy than a single-drug therapy and is worthy of clinical consideration.

Aldehyde Reductase↗
PubMed1992

Effects of nicotinamide and its isomers on iron-induced renal damage.

The effects of three isomers of pyridinecarboxamide (picolinamide (2-pyridinecarboxamide), nicotinamide (3-pyridinecarboxamide) and isonicotinamide (4-pyridinecarboxamide)) on iron-induced renal damage were studied. Pyridinecarboxamide (250 mg/kg body weight, ip) was administered 10 min before injection of ferric nitrilotriacetate (Fe(III)-NTA) (7.5 mgFe/kg body weight, ip). In picolinamide-treated rats, the renal tubular necrosis induced by Fe(III)-NTA was attenuated and serum creatinine did not increase. Picolinamide most efficiently suppressed renal lipid peroxidation in vivo-induced by Fe(III)-NTA. Non-heme iron levels in the kidneys after Fe(III)-NTA injection did not differ in groups to which pyridinecarboxamides were administered. To elucidate the protective effects of picolinamide, we studied the action of pyridinecarboxamides on lipid peroxidation and DNA damage in vitro. These isomers inhibited iron-induced lipid peroxidation of linolenic acid. Picolinamide had no effect on DNA damage, but nicotinamide and isonicotinamide promoted DNA damage by iron, especially when ascorbate was used as a reductant. None of these pyridinecarboxamide isomers changed the chlelate structure of Fe(III)-NTA as shown by electronic absorption spectra. Among the three isomers, picolinamide most effectively protected the kidneys against iron-induced renal damage, since it not only inhibited iron-induced lipid peroxidation, but also had little enhancing action on DNA damage by iron.

Amides↗
PubMed1991

Radical-promoting "free" iron level in the serum of rats treated with ferric nitrilotriacetate: comparison with other iron chelate complexes.

Iron plays a critical role in the production of activated oxygen species and the activity of chelated iron in the biological system depends on the chemical forms of the chelators. In the present study, we used ferric nitrolotriacetate (Fe-NTA, molar ratio of iron to chelators = 1:3), ferric ethylenediaminetetraacetate (Fe-EDTA, 1:3 complex) and ferric Desferal (Fe-Des, 1:1.1 complex) to see their "free" iron content in aqueous solutions in vitro and in the serum obtained after a single intraperitoneal injection of the chelates to rats (7.5 mg of iron/kg). "Free" iron was measured by the bleomycin-assay system. When Fe-NTA was dissolved in water, "free" iron increased linearly with total iron concentration up to 10 microM, whereas Fe-EDTA and Fe-Des showed no "free" iron with corresponding iron concentrations. When these three ferric chelates were dissolved in normal rat serum, "free" iron in Fe-NTA increased abruptly between 40 microM and 60 microM iron concentrations, then increased slowly up to 100 microM. Fe-Des did not show any "free" iron at comparable iron concentrations. Fe-EDTA had an intermediate "free" iron level in the serum. Among the ferric chelate complexes, Fe-NTA showed a much faster increase of and a higher content of "free" iron in the serum than the other two complexes after a single injection of the chelates into rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Amelioration of nerve Na(+)-K(+)-ATPase activity independently of myo-inositol level by PGE1 analogue OP-1206.alpha-CD in streptozocin-induced diabetic rats.

An oral prostaglandin E1 (PGE1) analogue, OP-1206.alpha-CD, was given to rats with streptozocin (STZ)-induced diabetes to examine the therapeutic effects of OP-1206 on short-term and long-term diabetic neuropathy and its action mechanism with special reference to nerve Na(+)-K(+)-ATPase activity. In the short-term experiment, OP-1206 was administered daily to diabetic rats in 3- and 30-mg/kg doses for 4 wk from the day of STZ injection. In the long-term study, 10 micrograms/kg OP-1206 was also given daily for 8 wk from 7 mo after induction of diabetes. The compound improved decreased sciatic motor nerve conduction velocity in both short-term and long-term diabetic rats. The nerve Na(+)-K(+)-ATPase activity of diabetic rats, reduced by 40% compared with controls, was reversed to the level of controls in both experiments, whereas weight loss and hyperglycemia were unchanged, and neither nerve sorbitol accumulation nor myo-inositol depletion was corrected. In a morphometric analysis of myelinated nerve fibers (MNFs) in long-term diabetes, the mean diameter of the largest 10% of MNFs was significantly reduced in untreated diabetic compared with control rats, but OP-1206 completely reversed this reduction. The results suggest that OP-1206 ameliorates a decrease in nerve Na(+)-K(+)-ATPase activity without any effect on nerve myo-inositol level and that the compound may be not only a potent therapeutic agent for the treatment of diabetic neuropathy but also a useful research tool to investigate the mechanism of nerve Na(+)-K(+)-ATPase activity regulation.

Alprostadil↗
PubMed1991

[Standardization of definitions concerning smoking behavior among Japanese adolescents--results from the Japan Adolescent Smoking Survey (JASS)].

The aim of the Japan Adolescent Smoking Survey (JASS) is to standardize the definitions of smoking behavior among Japanese adolescents together with measurement methods and questionnaires concerned. A study of 9921 school children aged 9 to 18 years in 17 elementary schools, 16 junior high schools and 18 senior high schools in 9 prefectures, was conducted between June and July of 1989, to determine the relationship between actual smoking behavior during the past month or year and the "self-referent label" concerning their smoking status. The main results were as follows: 1) The percentage of those who smoked at least one cigarette during the past month showed a high degree of similarity to the percentage of those who referred to themselves as "regular smokers" or "occasional smokers". 2) Less than 10% of students who identified themselves as "never smokers" or "ex-smokers" smoked at least one cigarette during the past month, while more than 80% of students who referred to themselves as "regular smokers" or "occasional smokers" smoked during the past month. 3) On the whole, those who smoked 20 or more cigarettes during the past month referred to themselves as "regular smokers"; those who smoked between 2 and 19 cigarettes as "occasional smokers"; those who smoked 1 cigarette as "ex-smokers"; those who did not smoke during the past month as "never smokers". 4) The definition where students who smoked one cigarette during the past month are classified as a category of smoker, displayed a high level of sensitivity and specificity for all school-level groups and for both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Effects of Tohoku Shinkansen noise on living environment of school children--changes with the increase of the maximum train speed].

The maximum train speed of the Tohoku Shinkansen was increased from 210 to 240 km/h in March 1985. In order to determine the effects of the expected increase in noise level on the living environment of school children, a longitudinal study was carried out in an elementary school near the Tohoku Shinkansen line in Saitama prefecture comprising noise measurements and social surveys of the school children and their mothers using a questionnaire. The results were as follows: 1. When measured 25 meters away from the railroad track, the noise level increased from 73 to 76 dB (A)along the inbound track, while it increased from 77 to 78 dB (A)along the outbound track. 2. The maximum noise level in a classroom when an outbound train passed at a speed of 216 km/h was 67 dB(A). 3. In the school environment the most pronounced effects of the Shinkansen noise were annoyance and listening disturbance, with the percentages reporting such significantly increasing after the speed-up. 4. In the home environment the most pronounced effects of the Shinkansen were annoyance, structural vibration, television interference, and listening disturbance. However, the percentages of these complaints did not show any significant change after the speed-up. 5. Among those living near the railroad track there were significant differences between children and their mothers in the percentages reporting annoyance, television and radio listening interference, and structural vibration, with the percentages for the mothers being higher than their children. These results indicate that disturbances in listening has especially increased in the school environment after the speed-up and that the increase in both noise levels and number of train passages have contributed to increasing disturbance.

Adult↗
PubMed1991

[Smoking and alcohol drinking behavior among Japanese adolescents--results from "Japan Know Your Body Study"].

The "Japan Know Your Body Study" (JKYB) is an example of collaborative activities of technology transfer carried out in Japan in several phases. The first phase is a needs assessment and data collection survey and it was administered during 1989. A survey was conducted throughout 9 prefectures in Japan with participation by 49 schools. Subjects were students in elementary, junior and senior high schools who ranged in age from 6 to 18 years. Participants, 12,892 in total, completed a survey on knowledge, attitude and behavior regarding cigarette smoking, alcohol drinking, diet, exercise and so on. The main results concerning cigarette smoking and alcohol drinking behavior were as follows: 1) The percentage of monthly male smokers rose remarkably from 8% in the third grade of junior high school to 37% in the third grade of senior high school, while that of female smokers showed a slow rise from 3% to 15%. The sex difference for smoking behavior was clear among senior high school students. 2) Smoking rates increased in proportion to the numbers of parents, siblings and friends who smoked. Above all, smoking behavior of friends was strongly related. Among senior high school students, for example, 50% of males and 46% of females who had two or more smoking friends were smokers, as compared to 5% of males and 2% of females with no smoking friends. 3) The percentage of monthly drinkers rose at a steady pace from 13% of males and 7% of females in the fifth grade of elementary schools to 59% of males and 50% of females in the third grade of senior high schools. The sex difference for alcohol drinking behavior among senior high school students, while statistically significant, was not as pronounced as that for smoking behavior. These results suggest that tobacco- and alcohol-use prevention programs should be introduced in elementary schools and those programs should include components relating to the social influences of parents, siblings and friends.

Adolescent↗
PubMed1991

Volatile N-nitrosamines in fish meal, with special reference to the mechanism of formation of N-nitrosothiazolidine.

Volatile N-nitrosamines in 32 commercial Japanese fish meal samples were analysed, and three compounds, N-nitrosodimethylamine, N-nitrosopyrrolidine and N-nitrosothiazolidine (NT), were detected. We also examined the mechanism of formation of NT during fish meal production. Both cysteamine and thiazolidine were found to be precursors of NT. The cysteamine content decreased during boiling and drying of the fish; but that of thiazolidine increased during boiling. N-Nitrosothiazolidine 4-carboxylic acid (NTCA) was formed in sardine meal after treatment with nitrogen dioxide gas, and the rate of formation of NT from NTCA added to sardine meal was as high as 10% when the meal was heated at 160 degrees C for 60 min. We propose two pathways for NT formation during fish meal manufacture: (1) cysteamine----thiazolidine----NT; and (2) cysteine----(thiazolidine 4-carboxylic acid)----NTCA----NT.

Carcinogens↗
PubMed1990

Biological characterization of human brain natriuretic peptide (BNP) and rat BNP: species-specific actions of BNP.

We examined the diuretic-natriuretic activities of rat BNP and human BNP in anesthetized rats in vivo and their vasorelaxant activities for rat thoracic aorta and porcine coronary artery in vitro. Rat BNP was almost equipotent to rat ANP in diuresis and natriuresis with relative potencies of 1.6 and 2.5, respectively, while human BNP exerted no significant activity. Rat ANP, rat BNP and human BNP relaxed PGF2 alpha-contracted rat aortic strips with IC50 values of 0.62, 0.64 and 12.1 nM, respectively, while they relaxed PGF2 alpha-contracted porcine coronary arteries with IC50 values of 0.04, 1.10 and 0.02 nM, respectively. These results strongly suggest that the biological action of BNP is species-specific.

Amino Acid Sequence↗
PubMed1990

Apolipoprotein B-48 analysis by high-performance liquid chromatography in VLDL: a sensitive and rapid method.

Apolipoprotein (apo) B subspecies were separated by high-performance liquid chromatography (HPLC) to analyze Apo B-48 contents in very-low-density lipoproteins (VLDL) more easily. Apo B-100 and B-48 were eluted through two connected column of Shim-pack Diol-300 at a retention time of 24 min and 32.3 min, respectively. The molecular masses estimated by this method were approximately 600 kDa in apo B-100, 220 kDa in apo B-48. % apo B-48 in total apo B (% B-48) determined by measuring peak area of HPLC-separated apo B in a healthy subject was 76% in chylomicrons, 13% in fasting VLDL, and 20% in 2 h-postprandial VLDL. No peak of apo B-48 was detected in LDL. Recovery of Apo B determined by re-chromatography of HPLC-separated sample was 91 +/- 4.0% and 95 +/- 3.6% in Apo B-100 and apo B-48, respectively. 125I-labeled apo B in VLDL were also analyzed by both HPLC and SDS-PAGE. Percent radioactivity of apo B-48 fraction in the total apo B determined by the HPLC (17.3%) was similar to the value obtained through the measurement of radioactivity separated by the SDS-PAGE (17.6%). Coefficient of variation in % B-48 determined by the peak area was 2.5%. Percent B-48 determined by the HPLC method was significantly correlated with % B-48 by SDS-PAGE, but 6-8 times higher, which might be accounted for in part by the reported difference of chromogenicity between apo B-100 and apo B-48. % B-48 in VLDL separated from fasting plasma were 17.1 +/- 5.6% in 14 healthy subjects, and positively related to VLDL triglyceride and cholesterol concentrations. Apo B isoprotein analysis by the HPLC method is reliable and easy to perform for studying apo B metabolism in triglyceride-rich lipoproteins in physiological as well as pathological conditions.

Adult↗
PubMed1990

Immunoenzyme localization of cathepsins in the Golgi region of rat hepatocytes and renal tubule cells.

Localization of carboxyl proteinase (cathepsin D) and cysteine proteinases (cathepsins B, H, and L) in Golgi region was studied using an immunoenzyme technique. Rat livers and kidneys were used. The results obtained from the livers were similar to those from the kidneys. All cathepsins were detected in lysosomal compartments such as secondary lysosomes, multivesicular bodies (endosomes), and autophagosomes. Rough endoplasmic reticulum (rER), including nuclear envelope was focally stained. Most of Golgi cisternae were negative, but sometimes only one cisterna or the terminal portion of the cisterna were stained focally. Rarely, the trans Golgi network (TGN) was positive for the proteinases. Among numerous Golgi vesicles, only a few of them were stained. The positive vesicles were divided into two groups, one had a bristle coat and heavily stained, and other were smaller than 40 nm in diameter and weakly stained. The small vesicles seemed to bud from the ER and to fuse with the Golgi cisternae, while the large clathrin-coated vesicles seem to bud from the TGN. The results suggests that cathepsins are transported by vesicular system from the rER to lysosomes via Golgi apparatus. In addition, it is suggested that the small vesicles transport the proteinases from the ER to the Golgi cisternae and the large clathrin-coated vesicles from the Golgi cisternae to the lysosomes.

Animals↗
PubMed1990

Inhibition of intracellular sorting and processing of lysosomal cathepsins H and L at reduced temperature in primary cultures of rat hepatocytes.

Our recent studies with pulse-chase kinetic analysis in primary cultures of rat hepatocytes suggest that newly synthesized lysosomal cathepsins H and L are initially synthesized as larger proform enzymes, and then the precursor molecules are subsequently converted to the mature enzymes by limited proteolysis during the intracellular sorting process. This proteolytic maturation of procathepsins appears to proceed within an acidic environment, and these processing events are closely connected with the activation of enzymes. To further characterize the intracellular processing site for lysosomal cathepsins H and L, the pulse-chase kinetic study was carried out at 20 degrees C in cultured rat hepatocytes, because the transport of the procathepsins was expected to be blocked at the trans-Golgi compartment at 20 degrees C. We show here that the newly synthesized procathepsins are accumulated intracellularly and the processing for lysosomal cathepsins is completely arrested at 20 degrees C along the sorting pathway. The procathepsins thus accumulated in the cell are presumed to be transported to the Golgi complex, since the oligosaccharide moieties of these polypeptides appear to be phosphorylated. When the cells were shifted to 37 degrees C after an incubation for 4 h at 20 degrees C, a gradual increase of the mature forms was found. However, the processing kinetics generating the mature enzymes were slow compared to those in control cells at 37 degrees C. When the NH4Cl was present in the cells after the temperature shift to 37 degrees C, the intracellular processing of procathepsins was considerably retarded and the release of intracellular procathepsins into the extracellular medium was observed. These results indicate that NH4Cl might exert the inhibitory effect on the mannose 6-phosphate receptor-mediated intracellular targeting mechanism for the lysosomal cathepsins. Hence, the intracellular location of procathepsins accumulated at 20 degrees C is considered to be in proximity to the trans-Golgi compartment. Taken together, the present observations suggest that the propeptide-processing step for procathepsins, which is a critical step for generating the active enzymes, proceeds within the prelysosomal compartment or the lysosomes after the enzymes leave the trans-Golgi compartment.

Ammonium Chloride↗
PubMed1990

[Analysis of factors associated with adolescent smoking by a follow-up survey].

One hundred and seventy-four second year senior high school students (106 males and 68 females) participated in a questionnaire survey to analyze factors associated with smoking. The questionnaire consisted of variables on family smoking, beliefs regarding smoking, knowledge about the dangers of smoking, etc. Smoking behavior about three and a half year later, when the subjects had become adults (twenty years old), was then investigated. The relationships between their behavior and the variables obtained in the earlier research were analyzed in detail. The results were as follows: 1) Family smoking was related to smoking behavior at the stage of second year of senior high school for males and to smoking onset after second year of senior high school for females. 2) Self-prediction regarding future smoking was related to both smoking behavior during senior high school and smoking onset in the future. Almost all beliefs regarding smoking was related to smoking behavior at the second year of senior high school, however, these beliefs were not effective in predicting future behavioral change. 3) Knowledge about the dangers of smoking was related to neither the smoking behavior at the stage of senior high school nor behavioral change in the future.

Adolescent↗