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T Katsura

Publications and source records attributed to T Katsura.

At least 19 recordsLinked to original sources
PubMed2004

Genetic and genotype x environment interaction effects for the content of seven essential amino acids in indica rice.

It is necessary for rice breeders to understand the genetic basis of nutrient quality traits of rice. Essential amino acids are most important in determining the nutrient quality of rice grain and can affect the health of people who depend on rice as a staple food. In view of the paucity of genetic information available on essential amino acids in indica rice, we estimated the genetic main effects and genotype x environment (G x E) interaction effects on the content of essential amino acids. Nine cytoplasmic male sterile lines as females and five restorer lines as males were introduced in a North Carolina II design across environments. Estimates of the content of the essential amino acids valine, methionine, leucine and phenylalanine showed that they were mainly controlled by genetic main effects, while the contents of threonine, cysteine and isoleucine were mainly affected by G x E effects. In the case of genetic main effects, both cytoplasmic and maternal genetic effects were predominant for all essential amino acids, indicating that selection for improving essential amino acid content based on maternal performance would be more effective than that based on seeds. The total narrow-sense heritabilities were high and ranged from 0.72 to 0.83. Since general heritabilities for these essential amino acids (except for cysteine) were found to be much larger than G x E interaction heritability, the improvement of content of most essential amino acids under selection would be expected under various environments. Rice varieties such as Zhenan 3, Yinchao 1, T49, 26715, 102 and 1391 should be selected as optimal parents for increasing the content of most essential amino acids, while the total genetic effects from Zhexie 2, Xieqingzao, Gangchao 1, V20, Zuo 5 and Zhenshan 97 were mainly negative and these parents could decrease the contents of most essential amino acids.

Amino Acids↗
PubMed2001

Promoter analysis for daily expression of Drosophila timeless gene.

Drosophila circadian clock gene timeless (tim) displays circadian oscillation in its mRNA level, and such oscillation is transcriptionally regulated. The promoter region up to -756 of tim is suggested to promote the circadian mRNA expression, however, the role of the sequence upstream of tim promoter region in the transcriptional regulation is still unrevealed. We novelly isolated and determined tim 5'-flanking sequence -2764 to -757, and found a putative cAMP-response element, six regions of the half site for PAR-basic leucine zipper transcription factors and six nonpalindromic E-boxes. Our in vivo reporter assay showed that 966 bp of tim promoter region, including a palindromic CACGTG E-box and a half site of PAR-basic leucine zipper transcription factors, was minimally required for its daily mRNA expression. While, the deletion of the 5'-flanking region -1970 to -967 caused a slight decrease in the reporter mRNA levels. These results indicate that the 5'-flanking sequence upstream of the promoter region have a role in the daily regulation of tim mRNA expression in Drosophila.

Animals↗
PubMed2001

Expression of peptide transporter following intestinal transplantation in the rat.

BACKGROUND: The absorptive function of the intestinal graft is one of the most important factors for successful intestinal transplantation. To clarify whether the intestinal H(+)/peptide cotransporter (PEPT1) was expressed in the transplanted intestine, we examined the expression of PEPT1 in an experimental model of rat small intestinal transplantation in comparison with expression of Na(+)/glucose cotransporter (SGLT1). MATERIALS AND METHODS: Heterotopic intestinal transplantation was performed in allogeneic and syngeneic rat strain combinations. An additional group of allogeneic recipients was treated with tacrolimus (1 mg/kg) prior to transplantation, then daily for 7 days. Intestinal grafts were examined for histopathology and PEPT1 and SGLT1 expression. RESULTS: In the isografts, the levels of messenger RNA (mRNA) encoding both transporters were not changed, while the amount of SGLT1 protein was decreased and that of PEPT1 protein was increased. In the allografts, mRNA level and protein amount of both transporters and the amount of villin protein were decreased, and microscopic examination revealed histopathological features of rejection on day 7. Tacrolimus treatment ameliorated the histopathological features and prevented the decrease in villin protein expression. However, the decreases in PEPT1 and SGLT1 expression (both mRNA and protein) were partially prevented by tacrolimus treatment. CONCLUSION: This study indicated that the expression of transporters should be determined to evaluate intestinal graft function in addition to histopathological examination of the mucosa and that the levels of mRNA encoding intestinal nutrient transporters in biopsy specimens may be useful for evaluating the intestinal graft function for intestinal transplant patients.

Animals↗
PubMed2001

Transport of levofloxacin in the OK kidney epithelial cell line: interaction with p-aminohippurate transport.

PURPOSE: To evaluate the mechanism of renal transport of quinolone antibacterial drugs, we examined the interaction of levofloxacin with p-aminohippurate (PAH) transport systems and the transport of levofloxacin in renal epithelial cells. METHODS: Transport of [14C]PAH or [14C]levofloxacin was measured using OK cell monolayers grown on microporous membrane filters. RESULTS: Transcellular transport from the basolateral to the apical side and cellular accumulation of [14C]PAH were inhibited by levofloxacin. Both the initial uptake of [14C]PAH from the basolateral side and the efflux to the apical side were inhibited by levofloxacin. The basolateral-to-apical transcellular transport of [14C]levofloxacin was greater than that in the opposite direction. [14C]Levofloxacin efflux to the apical side was greater than that to the basolateral side. Unlabeled levofloxacin and grepafloxacin inhibited the transcellular transport of [14C]levofloxacin, accompanied by an increase of cellular accumulation. However, neither PAH nor an anion transport inhibitor 4-4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) affected the basolateral-to-apical transport of [14C]levofloxacin nor its uptake from the basolateral side. CONCLUSIONS: These results indicated that levofloxacin inhibits PAH transport across both the basolateral and apical membranes of OK cells, but are not transported via the systems for PAH transport. The existence of a specific transport system for quinolones was indicated in OK cells.

Animals↗
PubMed2001

[Is routine application of off-pump coronary artery bypass grafting warranted?].

The limitation and indication of off-pump coronary artery bypass grafting (OPCAB) remain controversial. Since May 1999, we have applied OPCAB for all isolated coronary bypass cases routinely. Intraoperative conversion to CCAB occurred in 8 patients (10.8%). The main reasons for conversion were intramyocardial coronary arteries and arythmia-induced hemodynamic instability in the acute phase of myocardial infarction. We evaluated the results of OPCAB as compared to conventional coronary artery bypass (CCAB) as a historical control. The operative mortality was 1.6% in both groups. Postoperative complications including renal failure and requirements of circulatory support were significantly less in OPCAB. Postoperative max CPK-MB value, the amount of postoperative bleeding and the requirement of transfusion were also significantly less in OPCAB. Only neurological complication in OPCAB was temporary delirium in a high-aged patient, whereas three patients developed neurological complications including permanent stroke in CCAB. Right heart bypass was effectively utilized to maintain hemodynamics and expose the posterior vessels in patients with severely dilated and poorly functioning left ventricle (EF: 24-31%) and a patient with multiple severe stenosis in cerebral arteries. Coronary angiogram performed after the operation demonstrated 94% of graft patency. These results warrant the further application of OPCAB for multivessel surgical revascularization.

Adult↗
PubMed2000

Transepithelial transport of diphenhydramine across monolayers of the human intestinal epithelial cell line Caco-2.

PURPOSE: The transepithelial transport characteristics of the antihistamine, diphenhydramine, were studied in human intestinal Caco-2 cell monolayers to elucidate the mechanisms of its intestinal absorption. METHODS: The transepithelial transport and the cellular accumulation of diphenhydramine were measured using Caco-2 cell monolayers grown in Transwell chambers. RESULTS: The transepithelial transport of diphenhydramine from the apical to basolateral side was saturable, and the flux and cellular accumulation of diphenhydramine were dependent on the apical extracellular pH (pH 7.4 > 6.5 > 5.5). Transport and accumulation of diphenhydramine from the apical side were inhibited by another antihistamine, chlorpheniramine, while typical substrates for the renal organic cation transport system such as tetraethylammonium, cimetidine and guanidine had no effect. The transepithelial transport and cellular accumulation of diphenhydramine from the basolateral side were also pH-dependent and inhibited by chlorpheniramine. In addition, intracellular diphenhydramine preloaded was preferentially effluxed to the apical side, suggesting the involvement of the secretory pathway in diphenhydramine transport. Furthermore, diphenhydramine uptake from both the apical and basolateral sides was stimulated by preloading monolayers with chlorpheniramine (trans-stimulation effect). CONCLUSIONS: Transepithelial transport of diphenhydramine across Caco-2 cells is mediated by pH-dependent, specific transport systems that exist in both the apical and basolateral membranes.

Algorithms↗
PubMed2000

Diphenhydramine transport by pH-dependent tertiary amine transport system in Caco-2 cells.

Substrate specificity and pH dependence of the transport system for diphenhydramine were investigated in Caco-2 cell monolayers. Diphenhydramine uptake was not affected by any typical substrate for the renal organic cation transport system except procainamide. Along with procainamide, tertiary amine compounds with N-dimethyl or N-diethyl moieties in their structures inhibited the diphenhydramine uptake. Moreover, accumulation of diphenhydramine was stimulated by preloading the Caco-2 cells with these tertiary amines (trans-stimulation effect), indicating the existence of the specific transport system for tertiary amines with N-dimethyl or N-diethyl moieties. Efflux of diphenhydramine from monolayers was enhanced by medium acidification. In addition, intracellular acidification resulted in marked stimulation of diphenhydramine accumulation. ATP depletion of the cells caused an enhancement of diphenhydramine accumulation, suggesting the involvement of an active secretory pathway. However, P-glycoprotein did not mediate the diphenhydramine transport. These findings indicate that a novel pH-dependent tertiary amine transport system that recognizes N-dimethyl or N-diethyl moieties is involved in diphenhydramine transport in Caco-2 cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Transport of procainamide via H(+)/tertiary amine antiport system in rabbit intestinal brush-border membrane.

Transport characteristics of procainamide in the brush-border membrane isolated from rabbit small intestine were studied by a rapid-filtration technique. Procainamide uptake by brush-border membrane vesicles was stimulated by an outward H(+) gradient (pH(in) = 6.0, pH(out) = 7.5) against a concentration gradient (overshoot phenomenon), and this stimulation was reduced when the H(+) gradient was subjected to rapid dissipation by the presence of a protonophore, FCCP. An outward H(+) gradient-dependent procainamide uptake was not caused by H(+) diffusion potential. The initial uptake of procainamide was inhibited by other tertiary amines with N-dimethyl or N-diethyl moieties in their structures, such as triethylamine, dimethylaminoethyl chloride, and diphenhydramine, but not by tetraethylammonium and thiamine. Furthermore, procainamide uptake was stimulated by preloading the vesicles with these tertiary amines (trans-stimulation effect), indicating the existence of a specific transport system for tertiary amines. These findings indicate that procainamide transport in the intestinal brush-border membrane is mediated by the H(+)/tertiary amine antiport system that recognizes N-dimethyl or N-diethyl moieties in the structures of tertiary amines.

Amines↗
PubMed2000

Recycling of AQP2 occurs through a temperature- and bafilomycin-sensitive trans-Golgi-associated compartment.

The exo- and endocytotic pathway in which aquaporin-2 (AQP2) travels between the plasma membrane and intracellular vesicles is only partially characterized. It is known that the antidiuretic hormone vasopressin induces a translocation of AQP2 from an intracellular to a plasma membrane location, both in kidney collecting duct principal cells and in transfected epithelial cells. Here we provide evidence suggesting that while AQP2 shifts from an intracellular location to the cell surface in response to vasopressin, AQP2 also constitutively recycles through a similar pathway in transfected LLC-PK(1) cells even in the absence of hormonal stimulation. Incubating cells at 20 degrees C blocks AQP2 recycling in a perinuclear compartment, regardless of whether vasopressin is present. The H(+)-ATPase inhibitor bafilomycin A1 also blocks the recycling pathway of AQP2 in a perinuclear compartment adjacent to the Golgi in the presence and absence of vasopressin stimulation, indicating a role of vesicle acidification in both the constitutive and regulated recycling of AQP2. Colocalization of AQP2 with clathrin, but not with giantin, after both bafilomycin treatment and a 20 degrees C block suggests that the compartment in which recycling AQP2 is blocked may be the trans-Golgi, and not cis- and medial-Golgi cisternae.

Animals↗
PubMed2000

Improved synthesis of paroxetine hydrochloride propan-2-ol solvate through one of metabolites in humans, and characterization of the solvate crystals.

Paroxetine, a potent and selective inhibitor of 5-hydroxytryptamine (serotonin) uptake, was prepared through a piperidine derivative, which was reported to be one of the paroxetine metabolites in humans. Thus, the piperidine derivative was converted to its N-tert-butoxycarbonyl (N-Boc) derivative, which was then converted to N-Boc paroxetine. Paroxetine hydrochloride propan-2-ol (isopropyl alcohol (IPA)) solvate crystals were directly obtained from the N-Boc paroxetine by adding hydrogen chloride to the N-Boc paroxetine IPA solution. The amount of IPA content in the crystals was reduced by drying with a continuous change of powder X-ray diffraction patterns. Other characterizations of the solvate crystals were also conducted.

Crystallography, X-Ray↗
PubMed2000

[An autopsy case of systemic sclerosis with small cell carcinoma of the lung].

We report an autopsy of a 69-year-old woman who had systemic sclerosis with small cell carcinoma of the lung. She had interstitial pneumonia associated with systemic sclerosis and was admitted to our hospital because of acute on chronic respiratory failure due to a respiratory tract infection. Although she was treated with antibiotics, artificial respiration, and so on, she died 54 days after admission of exacerbation of respiratory failure. Histopathological examination at autopsy revealed intermediate cell type small cell carcinoma of the lung and usual interstitial pneumonia. It is generally said that the most common type of lung cancer associated with systemic sclerosis is adenocarcinoma or alveolar cell carcinoma, and that small cell carcinoma is rare. No autopsy case of systemic sclerosis with small cell carcinoma of the lung has ever been reported in Japan. Small cell carcinoma of the lung is more responsive to chemotherapy and radiotherapy than other histological types of lung cancer. Patients with small cell lung cancer are generally treated with chemotherapy alone or a combination of chemotherapy and radiotherapy. It is important to remember that the lung cancers that may be complicated with systemic sclerosis include not only adenocarcinoma and alveolar cell carcinoma but also small cell carcinoma of the lung, because the histological type may dictate the treatment.

Aged↗
PubMed2000

Evaluation of psychological effects due to bed rest.

The psychological condition of astronauts is an important factor for ensuring mission success in limited space. Head-down tilting bed rest is a well-accepted method by which to simulate an acute stage of human adaptation to the weightless state in space flight. In our previous studies, the enhancement of depressive and neurotic levels occurred during a 20-day horizontal bed rest. In this study, we attempted to examine the depressive and neurotic levels, the mood status, and behavioral tendency of the subjects and to analyze the changes of 24-hour urinary excretion of 17-hydroxycorticosteroid-glucronides (17-OHCS) for an indicator of changes in the endocrine system due to physical and psychological stress during a 20-day 6-degrees head-down tilting bed rest (BR).

17-Hydroxycorticosteroids↗
PubMed1999

Inhibitory effect of KW-3902, an adenosine A(1) receptor antagonist, on p-aminohippurate transport in OK cells.

KW-3902 (8-(noradamantan-3-yl)-1,3-dipropylxanthine) is a novel potent and selective adenosine A(1) receptor antagonist. We examined the effect of KW-3902 on p-aminohippurate (PAH) transport in opossum kidney (OK) epithelial cells. Pretreatment for 3 h with KW-3902 inhibited the transcellular transport of PAH across OK cell monolayers from the basal to the apical side. The uptake of PAH across the basolateral membrane of OK cells was inhibited by KW-3902 pretreatment in a time- and concentration-dependent manner. A kinetic analysis revealed that the inhibitory effect of KW-3902 on the basolateral PAH uptake was due to an increase in the Michaelis constant (K(m)) as well as a decrease in the maximum uptake rate (V(max)), showing that the inhibition was a mixed type. Pretreatment with adenosine deaminase or 8-cyclopentyl-1,3-dipropylxanthine, another selective adenosine A(1) receptor antagonist, also decreased the basolateral PAH uptake. KW-3902 pretreatment had no effect on the concentration of intracellular alpha-ketoglutarate which exchanges for PAH across the basolateral membrane of OK cells. These results suggest that KW-3902 has an inhibitory effect on PAH transport in OK epithelial cells.

Adenosine Deaminase↗
PubMed1999

Transport characteristics of diphenhydramine in human intestinal epithelial Caco-2 cells: contribution of pH-dependent transport system.

Transport characteristics of diphenhydramine, an antihistamine, were studied in cultured human intestinal Caco-2 cell monolayers to elucidate the mechanisms of its intestinal absorption. Diphenhydramine accumulation in the monolayers increased rapidly and was influenced by extracellular pH (pH 7.4 > 6.5 > 5.5). Diphenhydramine uptake was temperature dependent, saturable, and not potential sensitive. Kinetic analysis revealed that the apparent Km values were constant (0.8-1.0 mM) in all pH conditions tested, whereas Vmax values decreased at the lower pH. The initial uptake of diphenhydramine was competitively inhibited by another antihistamine, chlorpheniramine, with a Ki value of 1.3 mM. On the other hand, cimetidine and tetraethylammonium, typical substrates for the renal organic cation transport system, had no effect. Moreover, biological amines and neurotransmitters, such as histamine, dopamine, serotonin, and choline, also had no effect on the diphenhydramine accumulation. Finally, diphenhydramine uptake was stimulated by preloading monolayers with chlorpheniramine (trans-stimulation effect). These findings indicate that diphenhydramine transport in Caco-2 cells is mediated by a specific transport system. This pH-dependent transport system may contribute to the intestinal absorption of diphenhydramine.

Biological Transport, Active↗
PubMed1998

The postspinel phase boundary in Mg2SiO4 determined by in situ X-ray diffraction

The phase boundary between spinel (gamma phase) and MgSiO3 perovskite + MgO periclase in Mg2SiO4 was determined by in situ x-ray measurements by a combination of the synchrotron radiation source (SPring-8) and a large multianvil high-pressure apparatus. The boundary was determined at temperatures between 1400 degrees to 1800 degreesC, demonstrating that the postspinel phase boundary has a negative Clapeyron slope as estimated by quench experiments and thermodynamic analyses. The boundary was located at 21.1 (+/-0.2) gigapascals, at 1600 degreesC, which is approximately 2 gigapascals lower than earlier estimates based on other high-pressure studies.

Journal Article↗
PubMed1998

Vasopressin regulated trafficking of a green fluorescent protein-aquaporin 2 chimera in LLC-PK1 cells.

Aquaporin 2 (AQP2) transfected into LLC-PK1 cells functions as a vasopressin-regulated water channel that recycles between intracellular vesicles and the plasma membrane upon vasopressin stimulation. The green fluorescent protein (GFP) of the jellyfish, Aequorea victoria, was used as an autofluorescent tag to monitor AQP2 trafficking in transfected LLC-PK1 cells. Two chimeras were constructed, one in which GFP was fused to the amino-terminus of AQP2 [GFP-AQP2(NT)] and the second in which it was fused to the carboxyl-terminus [AQP2-GFP(CT)]. The GFP-AQP2(NT) chimera trafficked in a regulated pathway from intracellular vesicles to the basolateral plasma membrane in response to vasopressin or forskolin stimulation of cells. In contrast, the AQP2-GFP(CT) chimera expressed in LLC-PK1 cells was localized constitutively on both apical and basolateral plasma membranes. The cellular location of this chimera was not modified by vasopressin or forskolin. Thus, while the GFP-AQP2(NT) chimera will be useful to study AQP2 trafficking in vitro, the abnormal, constitutive membrane localization of the AQP2-GFP(CT) chimera suggests that one or more trafficking signals exist on the carboxyl-terminus of the AQP2 protein.

Amino Acid Sequence↗
PubMed1998

Cellular mechanisms of aquaporin trafficking.

Aquaporins (AQPs) are a family of functionally important water channel proteins that are of special cell biological interest because of their diverse intracellular targeting and trafficking properties. AQPs have been found in many different cells and tissues. This short review summarizes recent work that addresses the regulation of AQP2 trafficking in response to vasopressin.

Animals↗