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K Inui

Publications and source records attributed to K Inui.

At least 19 recordsLinked to original sources
PubMed2000

Inhibitory effect of anti-diabetic agents on rat organic anion transporter rOAT1.

The interactions of sulfonylureas and a novel anti-diabetic drug, nateglinide, with rat renal organic anion transporter (rOAT1) expressed in Xenopus laevis oocytes were studied. Uptake of p-aminohippurate via rOAT1 was markedly inhibited by glibenclamide and nateglinide, and moderately by chlorpropamide and tolbutamide. The inhibition constant values (K(i)) for chlorpropamide, glibenclamide, tolbutamide and nateglinide were 39.5, 1.6, 55.5 and 9.2 microM, respectively. Kinetic analysis showed that the inhibition of p-aminohippurate uptake by glibenclamide was competitive. Sulfonylureas examined and nateglinide did not show a trans-stimulation effect on [14C]p-aminohippurate efflux from rOAT1-expressing oocytes. There was no stimulation of [3H]glibenclamide uptake via rOAT1. These findings suggested that sulfonylureas and nateglinide interact with rOAT1, but these drugs are not translocated via the transporter.

Animals↗
PubMed2000

Hormonal regulation of organic cation transporter OCT2 expression in rat kidney.

Rat (r) OCT2 was identified as the second member of the organic cation transporter (OCT) family, and is predominantly expressed in the kidney. We reported previously that rOCT2 was responsible for the gender differences in renal basolateral membrane organic cation transport activity. As renal rOCT2 expression in males is much higher than that in females, we hypothesized that rOCT2 expression may be under the control of sex hormones. Treatment of male and female rats with testosterone significantly increased the expression levels of rOCT2 mRNA and protein in the kidney, whereas estradiol treatment moderately decreased the expression levels of rOCT2. There was no regulation of renal rOCT1 mRNA expression by testosterone or estradiol. Treatment of male and female rats with testosterone significantly stimulated the tetraethylammonium (TEA) accumulation by renal slices, whereas estradiol treatment caused a decrease in the TEA accumulation by slices from male but not female rats. The present findings suggested that testosterone up-regulates renal rOCT2 expression and estradiol moderately down-regulates rOCT2.

Animals↗
PubMed2000

Inhibitory effect of novel oral hypoglycemic agent nateglinide (AY4166) on peptide transporters PEPT1 and PEPT2.

The novel oral hypoglycemic agent nateglinide (AY4166) is a nonsulfonylurea insulin secretagogue, and its pharmacokinetic features include rapid absorption and elimination. As nateglinide is a dipeptide-like drug, we investigated the interaction of nateglinide with peptide transporters PEPT1 and PEPT2, which mediate the absorption of various peptide-like drugs. Nateglinide exhibited a potent inhibitory effect on [14C]glycylsarcosine uptake by the human colon adenocarcinoma cell line Caco-2 and rat PEPT-transfectants. Kinetic analysis revealed that these inhibitory effects were noncompetitive. Na(+)-coupled alanine or threonine uptake by Caco-2 cells was not inhibited by nateglinide, suggesting that the inhibitory effect of nateglinide on peptide transporters was not due to nonspecific interaction. There was little uptake of [14C]nateglinide by peptide transporters. Various sulfonylureas, such as glibenclamide, also inhibited [14C]glycylsarcosine uptake by rat PEPT-transfectants. In conclusion, nateglinide as well as sulfonylureas inhibit the transport activity of PEPT1 and PEPT2, although nateglinide itself is not transported by these transporters.

Administration, Oral↗
PubMed2000

Glycogen storage disease type Ia: molecular diagnosis of 51 Japanese patients and characterization of splicing mutations by analysis of ectopically transcribed mRNA from lymphoblastoid cells.

Glycogen storage disease type Ia (GSD-Ia) is an autosomal recessive disorder of glycogen metabolism caused by a deficiency of glucose-6-phosphatase (G6Pase) that is expressed in the liver, kidney, and intestinal mucosa. Clinical manifestations include short stature, hepatomegaly, hypoglycemia, hyperuricemia, and lactic acidemia. To elucidate a spectrum of the G6Pase gene mutations and their frequencies, we analyzed mutations in 51 unrelated Japanese patients with GSD-Ia. The most prevalent mutation was g727t, accounting for 88 of 102 mutant alleles examined, followed by R170X mutation, which accounted for 6 mutant alleles, and R83H mutation which was observed in 3 mutant alleles. In addition, 3 different, novel mutations, IVS1-1g<a, Gly122-to-Asp (G122D) and His179-to-Pro (H179P), were identified. We were able to detect "ectopically" transcribed G6Pase-mRNA in Epstein-Barr virus-transformed lymphoblastoid cells and observed aberrant mRNA splicing associated with the g727t and IVS1-1g<a mutations. To our knowledge, this is the first report that ectopic expression can be utilized for the characterization of GSD-Ia mutations. Our findings suggest that a screening for the g727t, R170X, and R83H mutations by simple DNA-based diagnostic methods can detect 95% of the G6Pase mutant alleles in Japanese patients with GSD-Ia, and remaining mutations can be identified and characterized by the direct sequencing of genomic DNA and/or the analysis of ectopically expressed mRNA. The noninvasive molecular diagnosis for GSD-Ia may ultimately replace the conventional means of enzymatic diagnosis that requires liver biopsy.

Alleles↗
PubMed2000

Role of apoptosis in cisplatin-induced toxicity in the renal epithelial cell line LLC-PK1. Implication of the functions of apical membranes.

The role of apoptosis and the implications of the functions of apical membranes in cisplatin-induced nephrotoxicity were investigated using the kidney epithelial cell line LLC-PK1. When LLC-PK1 cells were treated with 30 microM cisplatin, the number of floating cells was increased markedly. However, the number was not increased by treatment with 1 mM cisplatin, suggesting that different mechanisms were involved in the toxicities of these two treatments. DNA fragmentation, condensation of nuclear chromatin, and the absence of trypan blue staining suggested that cellular toxicity following treatment with 30 microM cisplatin for 24 hr was mediated predominantly by apoptosis. Specific activities of apical enzymes (gamma-glutamyltransferase, EC 2.3.2.2; and alkaline phosphatase, EC 3.1.3.1) in LLC-PK1 cells were decreased markedly by treatment with 30 microM cisplatin for 24 hr, whereas neither lactate dehydrogenase (LDH; EC 1.1.1.27) release nor a decrease in cellular protein content was observed following the same treatment. In addition, concomitant treatment with reduced glutathione completely attenuated both the apoptosis and the decrease of apical enzyme activities induced by 30 microM cisplatin. Neither DNA fragmentation nor condensation of chromatin was induced by treatment with 1 mM cisplatin for 12 hr. However, LDH release and a decrease in cellular protein level were induced by 1 mM cisplatin, suggesting that the toxic effect was due to necrosis. Under these conditions, specific activities of apical enzymes were not decreased. These results suggested that apoptosis was more responsible than necrosis for the loss of apical functions in cisplatin-induced toxicity in LLC-PK1 cells.

Animals↗
PubMed2000

Characterization of factors regulating lamina-specific growth of thalamocortical axons.

During development, most thalamocortical axons extend through the deep layers to terminate in layer 4 of neocortex. To elucidate the molecular mechanisms that underlie the formation of layer-specific thalamocortical projections, axon outgrowth from embryonic rat thalamus onto postnatal neocortical slices which had been fixed chemically was used as an experimental model system. When the thalamic explant was juxtaposed to the lateral edge of fixed cortical slice, thalamic axons extended farther in the deep layers than the upper layers. Correspondingly, thalamic axons entering from the ventricular side extended farther than those from the pial side. In contrast, axons from cortical explants cultured next to fixed cortical slices tended to grow nearly as well in the upper as in the deep layers. Biochemical aspects of lamina-specific thalamic axon growth were studied by applying several enzymatic treatments to the cortical slices prior to culturing. Phosphatidylinositol phospholipase C treatment increased elongation of thalamic axons in the upper layers without influencing growth in the deep layers. Neither chondroitinase, heparitinase, nor neuraminidase treatment influenced the overall projection pattern, although neuraminidase slightly decreased axonal elongation in the deep layers. These findings suggest that glycosylphosphatidylinositol-linked molecules in the cortex may contribute to the laminar specificity of thalamocortical projections by suppressing thalamic axon growth in the upper cortical layers.

Animals↗
PubMed2000

Structural requirements for determining the substrate affinity of peptide transporters PEPT1 and PEPT2.

Peptide transporters PEPT1 and PEPT2 transport numerous compounds including small peptides, peptide-like drugs and nonpeptidic compounds such as valacyclovir. PEPT1 and PEPT2 show low and high affinity for most substrates, respectively, but beta-lactam antibiotics without an alpha-amino group are the only known substrates that prefer PEPT1 to PEPT2. The aim of this study was to compare the recognition and affinity of various substrates between rat PEPT1 and rat PEPT2, and to determine the structural requirements influencing the substrate affinity. [14C]Glycylsarcosine uptake by PEPT1- or PEPT2-expressing transfectant was inhibited by di- and tripeptides, but not by amino acids, tetrapeptides or most cyclic dipeptides. All dipeptides and tripeptides examined showed more potent inhibition of [14C]glycylsarcosine uptake via PEPT2 than via PEPT1, irrespective of their charge and structure. Modification of the alpha-amino group of dipeptides reduced their substrate affinity to both transporters, as compared to unmodified dipeptides, but these dipeptides still showed potent inhibitory effects on PEPT2. Among the nonpeptidic substrates tested, only the eight-amino-octanoic acid displayed stronger inhibition of [14C]glycylsarcosine uptake in PEPT1 than in PEPT2. These findings suggest that alpha- or beta-amino carbonyl function is the key structure responsible for the higher affinity for PEPT2 than for PEPT1.

Animals↗
PubMed2000

Mutation analysis of two Japanese patients with Fanconi-Bickel syndrome.

Fanconi-Bickel syndrome (FBS), or glycogen storage disease type XI, is a rare autosomal recessive disorder characterized by hepatorenal glycogen accumulation, Fanconi nephropathy, and impaired utilization of glucose and galactose. Recently, this disease was elucidated to link mutations in the glucose transporter 2 (GLUT2) gene. Only three mutations in three FBS families have been reported. Therefore, it is important to elucidate mutations in the GLUT2 gene in FBS by answering the question of whether the syndrome is a single gene disease. In this report, we describe two patients in two unrelated families clinically diagnosed with FBS. No mutation in the entire protein coding region of the GLUT2 gene was detected in patient 1, which suggested that no mutation existed in the GLUT2 gene, or that some mutations had affected the expression of the GLUT2 gene. In patient 2, a novel homozygous nonsense mutation (W420X, Trp at codon 420 to stop codon) was detected. These results support the correlation between GLUT2 gene mutation and FBS syndrome. However, many patients must be analyzed to determine whether other genes are involved in FBS.

Adult↗
PubMed2000

Genetic grouping of classical swine fever virus by restriction fragment length polymorphism of the E2 gene.

A method for genetic grouping of classical swine fever viruses (CSFV) was developed based on the restriction fragment length polymorphism (RFLP) revealed by AvaII, BanII and PvuII digestion of RT-PCR amplified segments of the E2 gene. From inspection of the genetic sequences of Thai isolates and reference strains, the RFLP method was designed to be capable of differentiating all known genogroups and subgenogroups suggested by phylogenetic analysis of the CSFV E2 gene. The method was applied to 60 CSFV samples which included three genogroups and seven subgenogroups. Unlike previously described RFLP methods, the agarose gel patterns obtained from these samples were completely in agreement with the predicted RFLP patterns and enabled accurate genetic grouping of CSFV at the subgenogroup level. The simplicity of this method allows rapid CSFV genogrouping at diagnostic laboratories without sequencing facilities and provides a useful method for diagnosis as well as epidemiological investigation and control of classical swine fever outbreaks.

Animals↗
PubMed2000

A case of chronic infantile type of fucosidosis: clinical and magnetic resonance image findings.

Fucosidosis is a rare autosomal recessive disorder resulting from a deficiency of alpha-L-fucosidase. In this report, we describe clinical and magnetic resonance image (MRI) findings of a chronic infantile type patient heterozygous for a nonsense mutation and a large deletion. The disease onset occurred at 2-3 years of age. She was bound to a wheelchair at 6 years of age, and developed dystonia at the age of 13 years. Brain MRI at 13 years of age showed marked cerebral and cerebellar atrophy, high intensities in the white matter of the frontal and occipital lobes, and low intensities of the bilateral thalamus, striatum, substantia nigra, red nucleus and mamillary bodies on T2-weighted images. The low intensities of basal ganglia on T2-weighted images seems characteristic of lesions in fucosidosis.

Adolescent↗
PubMed2000

Transepithelial transport of levofloxacin in the isolated perfused rat kidney.

PURPOSE: The transepithelial transport of levofloxacin was evaluated in the isolated perfused kidney to investigate its renal secretory mechanisms. METHODS: Levofloxacin was instantaneously administered into the renal artery together with inulin and Evans blue-labeled albumin, and the single-pass dilution curves of the renal venous and urinary outflow were determined in the absence or presence of various compounds. Kinetic parameters were computed based on non-compartment moment analysis. RESULTS: The ratio of fractional excretion to filtration fraction (FE/FF) for levofloxacin was 2.99 +/- 0.18, indicating the involvement of tubular secretion. In the presence of cimetidine and quinolones, the FE/FF of levofloxacin was significantly decreased and the transepithelial mean transit time (Tcell) of levofloxacin was prolonged. The Tcell showed a negative correlation with renal secretion of levofloxacin, while the volume of distribution of levofloxacin showed no correlation. CONCLUSIONS: Transport on the brush-border membrane plays a determining step in the renal secretion of levofloxacin, and cimetidine and quinolones interact with levofloxacin transport on the brush-border membrane.

Animals↗
PubMed2000

N-terminal halves of rat H+/peptide transporters are responsible for their substrate recognition.

PURPOSE: Peptide transporters PEPT1 and PEPT2 differ substantially in their substrate affinity and recognition. The aim of this study is to define the structural domains which influence the functional characteristics of both transporters METHODS: Two kinds of chimeric peptide transporters (PEPT-N1C2 and PEPT-N2C1) were constructed, and their functional characteristics were compared with those of wild-type transporters in stable transfectants. RESULTS: PEPT-N1C2, the N-terminal half of rat PEPT1 and the C-terminal half of rat PEPT2, and the reciprocal chimera PEPT-N2C1 were functionally expressed in LLC-PK1 cells. The pH-profiles of [14C] glycylsarcosine uptake by PEPT-N1C2 and PEPT-N2C1 were close to those of PEPT1 and PEPT2, respectively. Substrate recognition for PEPT-N1C2 and PEPT-N2C1 was also similar to that of PEPT1 and PEPT2, respectively. However, substrate affinities for PEPT-N1C2 were higher than those for PEPT1, although those for PEPT-N2C1 and PEPT2 were comparable. CONCLUSIONS: These results indicate that functional regions which are associated with the extracellular pH changes and are responsible for substrate recognition of PEPT1 and PEPT2 may be located in the N-terminal halves of the proteins. In addition, it is suggested that the domain to affect the substrate affinity exists in the C-terminal as well as in the N-terminal half of rat PEPT2.

Animals↗
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

Volume measurement using tissue characterization of three-dimensional endoscopic ultrasonographic images.

BACKGROUND AND STUDY AIMS: Although it is time-consuming to measure the volume of lesions using three-dimensional endoscopic ultrasonography (3D-EUS), the technique is suitable for tissue characterization, as it allows images of multiple areas to be obtained simultaneously in uniform conditions. The present study tested automatic volume measurement using tissue characterization based on 3D-EUS. MATERIALS AND METHODS: Nine polygonal sections of resected spleen (volume 0.66 +/- 0.19 cm3) were immersed in water, and 40 radial 3D-EUS images were obtained. For tissue characterization, the methods of co-occurrence matrix and gray-level difference and discriminant analysis were used. Each spleen section was also measured using 3D-EUS. The volume of tissue identified as spleen using tissue characterization and the volume calculated on the basis of the 3D-EUS images were both compared with the actual volume measured beforehand. Measurements using tissue characterization and 3D-EUS were carried out for every third image. In three clinical cases of cancer the volume of the lesion was measured using tissue characterization and 3D-EUS. RESULTS: The mean volume of the nine splenic sections estimated using tissue characterization was 1.2 +/- 0.41 cm3 (mean +/- SD), while the mean volume estimated with 3D-EUS imaging was 1.1 +/- 0.30 cm3 (mean +/- SD). The volumes measured using tissue characterization were on average 13% larger than those obtained with 3D-EUS. Linear regression analysis showed a high degree of correlation between the two sets of measurements (r=0.97, P<0.00005), and also showed a high correlation between the volumes obtained using tissue characterization and the actual volume (r=0.93, P<0.0005). However, the volumes calculated using 3D-EUS images were larger than the actual volume (61% on average), and the volumes estimated using tissue characterization were also greater than the actual volume. The overestimation reflected the fact that measurement was only carried out in every third 3D-EUS image. In the clinical cases, the mean value for "true" tumor tissue as determined on EUS imaging represented 73% of the volume interpreted as cancer using tissue characterization. CONCLUSIONS: There was a good correlation between the volume measured with 3D-EUS and the volume obtained using tissue characterization. The tissue characterization volumes were only relatively slightly larger than the volumes measured using 3D-EUS, suggesting that there may be some promise for this application of tissue characterization.

Aged↗
PubMed2000

Effect of intestinal P-glycoprotein on daily tacrolimus trough level in a living-donor small bowel recipient.

We have examined whether the expression levels of the intestinal absorptive barriers, MDR1 gene product P-glycoprotein and cytochrome P450 IIIA4 (CYP3A4), correlate with the trough levels of orally administered tacrolimus in a recipient of small bowel transplant for 4 months. By using a competitive polymerase chain reaction, the expression of MDR1 messenger RNA (mRNA) and CYP3A4 mRNA by intestinal cells in a part of the mucosa biopsy specimen was evaluated. The average mRNA expression levels of MDR1 and CYP3A4 were 8.6 and 39.6 amol/microg total RNA, respectively. Both the MDR1 and CYP3A4 mRNA levels changed markedly throughout this period. The tacrolimus concentration/dose ratio correlated well with the mRNA expression level of MDR1, but not CYP3A4. These results suggested that intestinal P-glycoprotein rather than CYP3A4 is a good probe to predict the intraindividual variation in the tacrolimus pharmacokinetics during immunosuppressant therapy after small bowel transplantation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Long-term protective immunity to rinderpest in cattle following a single vaccination with a recombinant vaccinia virus expressing the virus haemagglutinin protein.

A recombinant vaccine, produced by using a highly attenuated smallpox vaccine (LC16mO) as a vector and which expresses the rinderpest virus (RPV) haemagglutinin protein, has been developed. The properties of this vaccine, including its heat stability, efficacy in short-term trials, safety and genetic stability, have been confirmed in an earlier report. In the present study, the duration of the protective immunity generated by the vaccine in cattle was examined for up to 3 years following the administration of a single vaccination dose of 10(8) p.f.u. The vaccinated cattle were kept for 2 (group I) or 3 years (group II) and then challenged with a highly virulent strain of RPV. Four of five vaccinated cattle in group I and all six cattle in group II survived the challenge, some showing solid immunity without any clinical signs of rinderpest. Neutralizing antibodies were maintained at a significant level for up to 3 years and they increased rapidly following challenge. Lymphocyte proliferative responses to RPV were examined in group II cattle and were observed in four of the six vaccinated cattle in this group. The long-lasting protective immunity, in addition to the other properties confirmed previously, indicate the practical usefulness of this vaccine for field use.

Animals↗
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↗