Biomedical subjects

T Kawabata

Publications and source records attributed to T Kawabata.

At least 73 records · Page 4Linked to original sources

PubMed1998

[The relationship between smoking behavior and self-esteem among elementary and junior high school students].

OBJECT: This study examined the relationship between smoking behavior and self-esteem among Japanese early adolescents. METHOD: The study sample comprised 1,486 fourth through ninth grade students from 10 elementary schools and six junior high schools throughout nine prefectures. Data were collected using an anonymous self-administered questionnaire which included items measuring smoking behavior, self-esteem, intention to smoke in the future, self-efficacy to refuse peer pressure to smoke, the smoking behaviors of their parents, siblings and friends. Self-esteem was measured using the Harter Perceived Competence Scale which includes four areas: cognitive, social, physical, and general. RESULTS: The main results were as follows: 1) Ever smokers had lower cognitive and general competence scores, but a higher physical competence score than never smokers, especially among males. 2) Ever smokers had more smoking parents, siblings and friends than never smokers. 3) Ever smokers had stronger intention to smoke in the future than never smokers. 4) Ever smokers had lower self-efficacy to refuse peer pressure to smoke than never smokers. CONCLUSION: The results of this study about the relationship between smoking behavior and self-esteem were consistent with those of some previous studies in the U.S. Therefore, it is suggested that effective smoking prevention programs for Japanese early adolescents should include strategies to enhance self-esteem.

Adolescent↗

PubMed1998

[Is patient-controlled sedation good for elderly patients?].

The purpose of this study was to evaluate the safety and advantage of intra-operative patient-controlled sedation (PCS) in elderly patients. Propofol PCS was compared with anesthesiologist-controlled sedation (ACS) during knee arthroplasty under epidural anesthesia. Eleven elderly patients scheduled for unilateral knee total or partial arthroplasty were divided randomly into PCS group (n = 6) and ACS group (n = 5). Epidural anesthesia was performed to produce an appropriate level of sensory block (T 10 through S). Firstly a mixture of pentazocine 0.2 mg.kg-1 and 2% mepivacaine 6-9 ml was injected to the epidural space, and anaesthesia was maintained using 2% mepivacaine afterward. Patients in both groups received propofol 0.3 mg.kg-1 i.v. as a loading dose and 0.6 mg.kg-1.h-1 continuous infusion. Furthermore patients in PCS group received propofol PCS (bolus: 0.2 mg.kg-1, lockout time: 3 min). Patients in ACS group were administered propofol continuously and infusion rates were regulated to maintain a sedation score 3 (Wilson et al) by anesthesiologist. Respiratory rate, blood pressure, heart rate, SpO2, arterial blood gas analysis and plasma levels of propofol were measured 4 times during and after the surgery. Satisfaction of patients and surgeons was questioned. Patients in PCS group received a mean propofol dose of 1.9 +/- 0.1 mg.kg-1 during procedures with a mean duration of 147 min. On the other hand patients in ACS group received propofol 2.9 +/- 0.3 mg.kg-1 with 142 min of procedures. Satisfaction of patients and surgeons, the incidence of complication were similar between the groups. For elderly patients who undergo epidural anesthesia, PCS is a safe and effective technique providing similar good sedation as with ACS.

Adjuvants, Anesthesia↗

PubMed1997

Characterization of B cells expressing recombination activating genes in germinal centers of immunized mouse lymph nodes.

Products of recombination activating genes (RAG-1 and RAG-2) involved in the rearrangement of Ig genes have been shown to be expressed only in immature stages of B cells. However, we have recently found that RAG genes were re-expressed in mature mouse B cells activated in vitro and in germinal centers (GCs) of immunized mouse lymph nodes (LNs). Here, we report that RAG transcripts and their proteins were expressed in parallel with the formation of GCs in popliteal LNs from mice immunized in the hind footpads. Immunocytochemical analysis revealed that RAG+ B cells were localized within GCs and were present as apoptotic tingible body cells. RAG expression is not considered a nonspecific result of apoptosis, since apoptotic B cells generated by surface Ig-engagement did not express RAG genes. These results suggest a novel role of RAG products in the differentiation of B cells in GCs.

Animals↗

PubMed1997

Improvement of protein secondary structure prediction using binary word encoding.

We propose a binary word encoding to improve the protein secondary structure prediction. A binary word encoding encodes a local amino acid sequence to a binary word, which consists of 0 or 1. We use an encoding function to map an amino acid to 0 or 1. Using the binary word encoding, we can statistically extract the multiresidue information, which depends on more than one residue. We combine the binary word encoding with the GOR method, its modified version, which shows better accuracy, and the neural network method. The binary word encoding improves the accuracy of GOR by 2.8%. We obtain similar improvement when we combine this with the modified GOR method and the neural network method. When we use multiple sequence alignment data, the binary word encoding similarly improves the accuracy. The accuracy of our best combined method is 68.2%. In this paper, we only show improvement of the GOR and neural network method, we cannot say that the encoding improves the other methods. But the improvement by the encoding suggests that the multiresidue interaction affects the formation of secondary structure. In addition, we find that the optimal encoding function obtained by the simulated annealing method relates to nonpolarity. This means that nonpolarity is important to the multiresidue interaction.

Amino Acid Sequence↗

PubMed1997

Iron-induced apoptosis in mouse renal proximal tubules after an injection of a renal carcinogen, iron-nitrilotriacetate.

Redox-active iron was demonstrated in mouse kidney by Timm's sulphide-silver staining after an injection of a renal carcinogen, iron-nitrilotriacetate (Fe-NTA). The iron was on the apical site of tubular epithelia of the renal proximal convoluted portion and in the tubules of the straight portion 30 min after the Fe-NTA injection. As the epithelial cells of the proximal tubules died, the iron disappeared in the dead cells and was stored in the cytoplasm of the more distal tubular epithelia. Biochemically, redox-active iron in the kidney rapidly increased to four times higher than the control 30 min after the Fe-NTA injection, then decreased to a plateau which was still higher than the control. Iron tightly stored in iron-storage proteins increased gradually by 3 h after the injection and then decreased at 5 h. The iron-induced free radical injuries, such as lipid peroxidation and protein oxidation, were demonstrated in the renal proximal tubules by histochemistry. The nuclei of the proximal tubular epithelia shrank and fragmented with the free radical injuries, and were positive for terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling. DNA ladder was demonstrated in the mice renal cortexes by agarose gel electrophoresis. It was elucidated that redox-active iron caused free radical injuries in the proximal tubules of mice kidneys after the injection of a renal carcinogenic iron (Fe-NTA) and induced the apoptosis of the proximal tubular epithelial cells.

Animals↗

PubMed1997

Relationship between aerobic power, blood volume, and thermoregulatory responses to exercise-heat stress.

To clarify the relationship between aerobic power (VO2max), blood volume (BV), and thermoregulatory responses to exercise-heat stress, we analyzed the cross-sectional relationship between the resting BV, plasma volume (PV), erythrocyte volume (EV), VO2max, forearm blood flow (FBF), and sweating responses during exercise in a hot environment (31 degrees C, 50% relative humidity). Twelve college-aged male subjects with a mean maximal oxygen uptake of 48 (range 42-59) mL.kg-1.min-1, a mean PV of 54 (range 42-72) mL.kg-1, a mean EV of 31 (range 23-43) mL.kg-1, and a mean BV of 85 (range 67-115) mL.kg-1 (measured by the Evans Blue dye dilution method) performed three sessions of 20-min cycle exercise at two levels of intensity (40% and 60% VO2max). The BV, PV and EV correlated positively with peak FBF (r = 0.596-0.711, P < 0.05), the increase of FBF in response to a unit rise in esophageal temperature (Tes; peak delta FBF/peak delta Tes) (r = 0.592-0.656, P < 0.05) and with total sweat loss (TSL) (r = 0.599-0.634, P < 0.05) during the exercise. The VO2max correlated with TSL during exercise at 40% VO2max (r = 0.578, P < 0.05), but not with peak FBF and peak delta FBF/peak delta Tes. The VO2max per lean body mass also showed a significant positive correlation with BV (r = 0.769, P < 0.01), PV (r = 0.706, P < 0.05), and with EV (r = 0.841, P < 0.001). The peak delta FBF/peak delta Tes was correlated positively with peak FBF (r = 0.597-0.830, P < 0.05-0.01) and negatively with peak Tes (r = 0.641-0.769, P < 0.05-0.01) during the exercise at the two levels. However, the chest sweat rate (CSR), TSL, and the increase of CSR in response to a unit rise in Tes (peak delta CSR/peak delta Tes) showed no correlation with peak Tes during the exercise at the two levels. These findings suggest that 1) heat dissipation responses during exercise were related more to blood volume than aerobic power and 2) skin blood flow was related more to body temperature than sweating responses during exercise under mild heat stress.

Adolescent↗

PubMed1997

Copper and iron-induced oxidative damage in non-tumor bearing LEC rats.

The copper and iron status in the liver of non-tumor bearing Long-Evans Cinnamon (LEC) rats (average age 17 months) was investigated. A direct quantitation of loosely-bound copper and iron was also investigated by using a chelating agent, nitrilotriacetic acid (NTA-chelatable free copper and iron). Besides the total copper and iron contents, the level of NTA-chelatable free copper was also higher in LEC rats than in LEA rats (P<0.05). But for the free iron level there was no significant difference between the two rat groups (P>0.05). The formation of thiobarbituric acid-reactive substances was higher in LEC rats than in LEA rats (P<0.01). The 4-hydroxy-2-nonenal (HNE)-modified proteins were also clearly demonstrated in LEC rat liver. The copper and iron which produced the most important effect in the process of oxidative damage in LEC rats could not be distinguished. Even though free copper, which could induce free radical injuries, was increased in LEC rats, neither tumor-induction nor preneoplastic lesions in the experimental LEC rats were observed. Therefore it is speculated that the elevation of a free iron is another important factor. Copper and iron, both important transition metals in the body, may participate in the induction of DNA damage and oncogenesis.

Animals↗

PubMed1997

Inhibitory effects of Chinese ant extract (CAE) on nephrotoxicity induced by ferric-nitrilotriacetate (Fe-NTA) in Wistar rats.

We observed the inhibitory effects of Chinese ant extract (CAE), a Chinese traditional medicine, on nephrotoxicity induced by Fe-NTA in Wistar rat. Strong positive staining with Schiff's reagent was found in the proximal tubules of the untreated control rats. In contrast, the positivity was very weak in CAE treated rats. The level of TBARS was also higher in the untreated control rats than in CAE treated rats. Meanwhile, the scavenging effect of CAE on hydroxyl radicals was analyzed by electron spin resonance (ESR) in vitro. The results indicate that CAE can efficiently prevent Fe-NTA induced nephrotoxicity through quenching free radicals mechanism.

Animals↗

PubMed1996

Post-infectious encephalitis with anti-galactocerebroside antibody subsequent to Mycoplasma pneumoniae infection.

Galactocerebroside (Gc) is a major component of myelin in both the peripheral and central nervous systems. Although it is regarded as an important glycolipid hapten of myelin in rabbit experimental allergic neuritis (EAN), its role in human demyelinating diseases is not known. We studied three post-infectious encephalitis (PIE) patients related to Mycoplasma pneumoniae infection. All three of three patients with encephalitis and M. pneumoniae infection were positive for Gc antibodies (100%), while 25% of 32 M. pneumoniae-infected patients without neurological disease were positive, and 3.8% of 52 healthy controls. This indicates anti-Gc antibody is induced by M. pneumoniae infection. One of the PIE patients, who had extraordinary high titer antibody to Gc, showed an extensive, diffuse white matter demyelination and poor recovery. Since circulating anti-Gc antibody induces central nervous system demyelination in animals with elevated antibody titers and disruption of the blood-brain barrier, anti-Gc antibody may have an important function in the increased demyelination in PIE patients after M. pneumoniae infection.

Antibodies↗

PubMed1996

Iron coordination by catechol derivative antioxidants.

Iron complexes of nitrocatechols with different substituent groups [1: -CH = CR2; 2: -CH2-CHR2; 3: -CH = CR'(R")] were synthesized and their effects on iron-induced free radical reactions of biological importance investigated. Catechol and nitrocatechol derivatives effectively inhibited iron-induced lipid peroxide-dependent lipid peroxidation. In the Fenton-like reaction, iron-catechol generated hydroxyl radicals more strongly than did iron citrate, and iron-nitrocatechol derivative 2 generated a small amount of hydroxyl radicals. The iron complexes of derivatives 1 and 3 did not generate hydroxyl radicals. Iron-catechol had the highest ratio of reduction to oxidation rate constants and the second was iron-nitrocatechol 2, suggesting that iron chelated by nitrocatechols 1 and 3 may be most difficult to reduce. To elucidate the structure and physical properties of the iron complexes, UV/vis absorption spectroscopic, ESR and 1H NMR studies were performed in aqueous and DMSO solutions. In aqueous solution at pH 7.4, iron complexes of the nitrocatechol derivatives were high-spin tris(nitrocatecholato)ferrate(III) with a characteristic ligand-to-metal charge transfer absorbance (pi -> d pi). The lambda max of iron-nitrocatechol derivative 2 was shorter than those of iron-nitrocatechol derivatives 1 and 3, suggesting that the reduction potential of iron-nitrocatechol 2 is higher than that of iron-nitrocatechols 1 and 3. Nitrocatechol derivatives with a conjugation structure can sequester the chelated iron more effectively than catechol and the derivative without the conjugation against free radical generation by keeping the iron in the ferric state, probably because of the reduction potentials.

Animals↗

PubMed1996

Ginseng extract scavenges hydroxyl radical and protects unsaturated fatty acids from decomposition caused by iron-mediated lipid peroxidation.

This study was conducted to investigate whether or not the antioxidation effect of ginseng extract directly inhibits decomposition of unsaturated fatty acid caused by iron and hydrogen peroxide-induced lipid peroxidation, and whether this effect involves a hydroxyl radical-scavenging mechanism. Thiobarbituric acid-reactive substances (TBARS), gas chromatography, and electron spin resonance (ESR) spectrometer were used to measure lipid peroxidation, unsaturated fatty acid, and hydroxyl radical. The results showed TBARS formed and the loss of arachidonic acid during lipid peroxidation, and that hydroxyl radical formed by the Fenton reaction were completely inhibited by ginseng extract. This antioxidant effect of ginseng may be responsible for its wide pharmacological actions in clinical practice by a free radical reaction-inhibition mechanism.

Arachidonic Acid↗

PubMed1996

Oxidative damages by iron-chelate complexes depend on the interaction with the target molecules.

To elucidate that in iron-catalyzed oxidative damage the interaction of iron complex with the target molecules is important, the oxidative damage to plasmid DNA, protein and fatty acid has been compared using iron-chelate complexes with nitrilotriacetic acid (nta), citric acid, ethylenediamine-N,N'-diacetic acid (edda) and diethylenetriamine-N,N,N',N",N"-pentaacetic acid (dtpa). In the presence of hydrogen peroxide, plasmid pBR322 strand breaks occurred in the order of Fe-edda > Fe-citrate > Fe-nta > > Fe-dtpa. However, fragmentation of bovine serum albumin and diene conjugation of linoleic acid micelle occurred in the order of Fe-nta > Fe-edda > > Fe-citrate > Fe-dtpa = O, which were similar to hydroxyl radical production by these iron complexes and H2O2. Bleomycin-detectable free radical-promoting irons in these iron complexes were about 85% of iron in Fe-nta, Fe-citrate and Fe-edda, and only about 33% in Fe-dtpa. Not only hydroxyl radical productivity and free radical-promoting iron content in iron complex, but also the interaction of the complex with the target molecules determines the iron-catalyzed oxidative damage.

Animals↗

PubMed1996

2D NMR of the metabolic antioxidant dihydrolipoic acid and its derivatives.

Dihydroplipoate and lipoate are physiological thiols which in addition to their coenzyme functions exhibit antioxidant activity. For NMR investigations of their protective mechanism in biological and model systems it is very important to know the full assignment of proton and carbon spectra of these molecules in water (D2O). An unambiguous assignment of proton and carbon NMR spectra has been made for dihydrolipoate and its short chain derivatives bisnor- and tetranor-lipoic acid in D2O and CDCl3 solutions using 2D NMR methods. Oxidation of dihydrolipoic acid produces substantial electron density deshielding of the carbons nearest to the SH groups with the largest shift found at the inner SH group (17.79 ppm in D2O, 16.93 in CDCl3) and almost no changes in the tail portion of the molecule. However, bisnor-dihydrolipoic acid and especially tetranor-dihydrolipoic acid have more carbon deshielding near the outer SH group of the molecule which correlates with their known diminished ion chelating activity. Moreover, the proton triplet at position 2 of lipoic acid has strong pH dependence (pK = 4.58) due to the close proximity to the carboxylic group and this feature may be used for monitoring pH.

Antioxidants↗

PubMed1996

[The short-term effect of a smoking prevention program for the upper graders of elementary schools--the results of intervention study for two years with quasi-experimental design].

The purpose of this study was to evaluate the short-term effect of a smoking prevention program for Japanese elementary school-children in the fifth and sixth grades. The program was developed with concepts found in the Know Your Body Program and the conclusions of a National Cancer Institute-convened Expert Advisory Panel, and focused on teaching about the short-term effects of smoking and on resistance to social pressures to smoke. The study was conducted with a quasi-experimental design. An intervention group (52 boys and 54 girls) received three sessions for both the fifth grade in 1992 and the sixth grade in 1993. Moreover, the intervention group received a pre-test before the first session and a post-test after the third session in each grade. A comparison group (102 boys and 91 girls) received the same tests at the same time as the intervention group, but did not receive any program on smoking prevention. The short-term effect of the program were evaluated using the results of the pre-test in the fifth grade and of the post-test in the sixth grade in both groups. The results were as follows: 1) Remarkable short-term effects of the intervention were seen in respect to awareness of the importance of not smoking in girls, and also in the knowledge of the short-term effects of smoking in both sexes. 2) The intervention was not effective with respect to intention to smoke at the age of 20 and self-efficacy of refusing to smoke in both sexes. 3) The short-term effects were not clear in the smoking behavior in both sexes because the rates of ever smokers and of monthly smokers were almost the same for two years between the intervention group and the comparison group. 4) The smoking behaviors of children, their parents and their best friends had little influence on the results of the post-test in the sixth grade.

Age Factors↗

PubMed1995

Role of ascorbate in protection by nitecapone against cardiac ischemia-reperfusion injury.

The antioxidant properties of nitecapone, a catechol derivative and an inhibitor of catechol-O-methyltransferase, were reported recently. In the present study, the influence of nitecapone on isolated rat heart ischemia-reperfusion injury was investigated to elucidate its cardioprotective role. Nitecapone, administered in the perfusion buffer from the beginning of the pre-ischemic phase, significantly improved recovery of cardiac mechanical function, suppressed enzyme leakage in the coronary effluent, and minimized loss of ascorbate, compared with the control group. In rats fed a diet containing 4% ascorbate, myocardial ascorbate content in ascorbate-fed rats after ischemia-reperfusion was higher than that in control rats fed a normal diet without ischemia. However, supplemented rats did not show any beneficial effects on cardiac mechanical recovery or enzyme leakage, suggesting that maintenance of tissue ascorbate level is not the cause, but the result of the protective effects of nitecapone against cardiac ischemia-reperfusion injury. The iron-chelating effect of nitecapone was also tested. It was confirmed, using electron spin resonance, that 50 microM nitecapone chelates the same concentration of iron released from the heart into the coronary effluent. Hence, the iron-chelating ability of nitecapone may be responsible, at least in part, for its cardioprotective effects in ischemia-reperfusion injury.

Animals↗

PubMed1995

Molecular cloning of insect pro-phenol oxidase: a copper-containing protein homologous to arthropod hemocyanin.

Pro-phenol oxidase [pro-PO; zymogen of phenol oxidase (monophenol, L-dopa:oxygen oxidoreductase, EC 1.14.18.1)] is present in the hemolymph plasma of the silkworm Bombyx mori. Pro-PO is a heterodimeric protein synthesized by hemocytes. A specific serine proteinase activates both subunits through a limited proteolysis. The amino acid sequences of both subunits were deduced from their respective cDNAs; amino acid sequence homology between the subunits was 51%. The deduced amino acid sequences revealed domains highly homologous to the copper-binding site sequences (copper-binding sites A and B) of arthropod hemocyanins. The overall sequence homology between silkworm pro-PO and arthropod hemocyanins ranged from 29 to 39%. Phenol oxidases from prokaryotes, fungi, and vertebrates have sequences homologous to only the copper-binding site B of arthropod hemocyanins. Thus, silkworm pro-PO DNA described here appears distinctive and more closely related to arthropod hemocyanins. The pro-PO-activating serine proteinase was shown to hydrolyze peptide bonds at the carboxyl side of arginine in the sequence-Asn-49-Arg-50-Phe-51-Gly-52- of both subunits. Amino groups of N termini of both subunits were indicated to be N-acetylated. The cDNAs of both pro-PO subunits lacked signal peptide sequences. This result supports our contention that mature pro-PO accumulates in the cytoplasm of hemocytes and is released by cell rupture, as for arthropod hemocyanins.

Amino Acid Sequence↗

PubMed1995

Kinetic studies on the interaction of nonlabeled antagonists with the angiotensin II receptor.

Angiotensin AT1 receptor antagonists are divided into two types, surmountable and insurmountable, based on the way they inhibit angiotensin II-induced vasoconstriction. To elucidate what causes the difference, we studied how antagonists associate with and dissociate from AT1 receptor sites in rat liver membranes. Three antagonists, 6-propyl-7-oxo-4[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-4,7- dihydropyrazolo[1,5-a]pyrimidine-3-carboxylic acid (SRL1080227), 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H- benzimidazole-7-carboxylic acid (CV-11974) and 2-butyl-3-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-3H-imidazo- [4,5-b]pyridine (FK739), showed competitive antagonism when they were added simultaneously with [125I]angiotensin II, but CV11974 and SRL1080227 showed apparently noncompetitive antagonism when membranes were preincubated with each antagonist. The longer the preincubation time with CV11974 or SRL1080227 was, the more effectively the antagonist inhibited [125I]angiotensin II binding, while the inhibition by FK739 did not change with the preincubation time. To estimate their dissociation rate from the receptor binding site, we studied [125I]angiotensin II binding to membranes which had been preincubated with each antagonist and washed twice. Membranes pretreated with FK739 completely recovered the ability to bind [125I]angiotensin II with a period of 60 min, while membranes preincubated with CV11974 did not read this level of recovery. [125I]angiotensin II binding to membranes preincubated with SRL1080227 increased gradually, but did not reach the control level during the experiment. The kinetic properties of SRL1080227, CV11974 and FK739 were consistent with their characteristic modes in inhibiting angiotensin II-induced contraction of isolated rabbit aorta and decreasing blood pressure of spontaneously hypertensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin Receptor Antagonists↗

PubMed1995

Effect of aerobic capacity on sweat rate and fluid intake during outdoor exercise in the heat.

We measured the aerobic capacity, sweat rate and fluid intake of trained athletes during outdoor exercise and examined the relationship between aerobic capacity and thermoregulatory responses at high ambient temperatures. The maximal aerobic capacity (VO2max) of the subjects, nine male baseball players of college age, was determined by maximal exercise tests on a cycle ergometer. The subjects practised baseball regularly without drinking fluids from 1330 to 1530 hours. After 30 min rest, they played a baseball game with free access to a sports drink at 15 degrees C from 1600 to 1830 hours. At a mean ambient temperature of 36.7 (SEM 0.2) degree C, the mean percentage of body mass loss (delta mb) and increase of oral temperature (delta To) from 1330 to 1530 hours was 3.47 (SEM 0.12)% and 0.81 (SEM 0.14) degree C, respectively. The sweat loss from 1330 to 1830 hours was 56.53 (SEM 1.56)ml.kg-1 of body mass (mb) while the mean fluid consumption was 44.78 (SEM 2.39)ml.kg-1 of mb, with recovery of 76.08 (SEM 2.81)% of sweat loss. The VO2max was significantly inversely correlated with delta mb, fluid intake and rehydration amount, but showed no correlation with delta To. These results would suggest that at a given exercise intensity in subjects with a higher aerobic capacity body temperature is maintained with a lower sweating rate than that in subjects with a lower aerobic capacity.

Adult↗