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Biomedical subjects

K Inui

Publications and source records attributed to K Inui.

At least 199 records · Page 11Linked to original sources
PubMed1997

Kinetic analysis of tetraethylammonium transport in the kidney epithelial cell line, LLC-PK1.

PURPOSE: The aims of this study were to establish a kinetic means of analyzing the membrane transport of organic cations in renal epithelial cells, and to simultaneously evaluate drug interactions in apical and basolateral membranes. METHODS: Tetraethylammonium (TEA) transport was measured using LLC-PK1 cell monolayers grown on microporous membrane filters. After incubating the cells with unlabeled TEA or other drugs, apical or basolateral medium was changed to that containing labeled TEA, and transcellular transport and cellular accumulation were measured. Clearance from apical medium to cells (CL12), cells to apical medium (CL21), cells to basolateral medium (CL23) and basolateral medium to cells (CL32) were calculated based on a three compartment model. RESULTS: TEA was accumulated progressively in the monolayers from the basolateral side and was transported unidirectionally to the apical side. CL32 was greater than CL12 and CL23 was greater than CL21. Therefore, the rate limiting step of TEA transport from the basolateral to the apical medium was the cell-to-apical step. Co-incubation of TEA with procainamide decreased the transport parameters of TEA, CL12, CL21 and CL32, whereas that with levofloxacin decreased only CL12 and CL21, not affecting the parameters in basolateral membranes. CONCLUSIONS: Using a simple model, we analyzed the transport of organic cation in kidney epithelial cell line, LLC-PK1. This method can be useful for the analysis of cation transport and drug interactions in the apical and basolateral membranes of renal tubules.

Animals↗
PubMed1997

Three-dimensional intraductal ultrasonography: preliminary results of a new technique for the diagnosis of diseases of the pancreatobiliary system.

BACKGROUND AND STUDY AIMS: Intraductal ultrasonography (IDUS) is a useful method for the diagnosis of pancreatobiliary diseases, but the images obtained using the presently available ultrasonic probes are limited by their two-dimensional nature and are sometimes difficult to interpret. The possible application of three-dimensional intraductal ultrasonography (3 D-IDUS) to facilitate the diagnosis of pancreatobiliary disease was therefore studied using a newly developed system. PATIENTS AND METHODS: 3 D-IDUS of the biliary system was performed on 26 patients with benign (n = 100) or malignant pancreatobiliary diseases (n = 16), via percutaneous transhepatic or peroral approaches. Three-dimensional diagnoses were made using both radial and linear images generated on the monitor of this system along with a comparison with conventional IDUS (2 D-IDUS) findings. RESULTS: The courses of vessels surrounding the bile duct could be easily imaged in all cases, and accurate assessment of tumor extension and the relationship with surrounding organs could be achieved for all the malignancies. In four of six cases of bile duct cancers the whole outline of the tumor could be visualized so that the tumor volumes could be measured. CONCLUSIONS: These preliminary results of 3 D-IDUS in the pancreatobiliary system, the first to be reported in the English literature, indicate that this new system has clear advantages over the 2 D-IDUS approach for diagnostic purposes. Further technical improvements can be expected which will ensure a clinical role for 3 D-IDUS.

Adult↗
PubMed1997

Unsuccessful omentopexy in thoracic surgery.

Omentopexy has improved the treatment of chronic empyema and postpneumonectomy bronchopleural fistula, which otherwise are difficult to manage. However, omentopexy is not effective in some patients. Four of 17 patients who underwent omentopexy in our institution between January 1978 and March 1994 did not respond to the treatment and died. In two patients, a dead space remained after surgery and there was insufficient sterilization. In one patient, a dead space appeared after surgery and it was impossible to control infection. The fourth patient had dehiscence of the anastomosis triggered by postoperative acute gastritis. All four patients in whom omentopexy was not successful died. When omentopexy is used for empyema, the space should first be sterilized. If sterilization is insufficient, muscle filling and thoracoplasty must be performed and no dead space left.

Adult↗
PubMed1997

"Reversed" latissimus dorsi musculocutaneous flap for closure of large bronchopleural fistula.

The patient was a 54-year-old male with diabetes mellitus and liver abscess perforating into the right lung through the diaphragm. After right lower lobectomy of the lung, S3-segmentectomy of the liver, and debridement of the subdiaphragmatic abscess a bronchopleural fistula appeared. After open-drainage thoractomy, secondary operation for closure of a large bronchopleural fistula and obliteration of the empyema cavities was performed with a "reversed" latissimus dorsi musculocutaneous flap.

Bronchial Fistula↗
PubMed1997

Haplotype and mutation analysis in Japanese patients with Wilson disease.

Wilson disease (WD), an autosomal recessive disorder of copper transport, is characterized by impaired biliary excretion and by impaired incorporation of copper into ceruloplasmin. Toxic accumulation of copper causes tissue damage, primarily in the liver, brain, and kidneys. The gene for WD (ATP7B) has been cloned, and the protein product is predicted to be a copper-transporting P-type ATPase with high amino acid identity with that for Menkes disease, an X-linked disorder of copper transport. Mutation screening in WD patients has led to the identification of at least 40 mutations. In addition, haplotype analysis using three dinucleotide-repeat markers, D13S314, D13S301, and D13S316, has been a useful indicator of specific mutations. We have determined haplotypes for the patients and their parents and sibs, in 21 unrelated WD families from Japan. Twenty-eight different haplotypes were observed on 42 WD chromosomes. In all the patients, the ATP7B coding sequence, including the intron-exon boundaries, was screened for mutations, by SSCP, followed by direct-sequence analysis of the shifted fragments. We identified 13 mutations, of which 11 mutations are novel, including 7 mutations-1 insertion, 4 deletions, and 2 missense mutations-in the coding region. The mutations reported in previous studies are 2299insC and Arg778Leu. Two patients were shown to have the 2299insC mutation, which has occurred in many different haplotypes in several populations, indicating a mutation hot spot. Primer-extension analysis of ATP7B mRNA has revealed multiple transcription start sites. Four of the novel mutations (three 1-bp changes and one 5-bp deletion) occur in the 5' UTR and may result in altered expression of the WD gene.

Adenosine Triphosphatases↗
PubMed1997

Renal excretion of vancomycin in rats with acute renal failure.

We have investigated the renal excretion of vancomycin in rats with acute renal failure (ARF) induced by uranyl nitrate or cisplatin. The renal clearance of the antibiotic after uranyl nitrate or cisplatin injection was separately evaluated by calculating the glomerular filtration rate (GFR) and secretory clearance. The reduced renal clearance of vancomycin in these ARF rats was a result of a decrease in both GFR and secretory clearance. The extents of the decreases in GFR and in secretory clearance were not, however, proportional, the extent of the decrease in secretory clearance being more pronounced. These results suggest that the renal tubular secretion of vancomycin was reduced more predominantly than glomerular filtration in these ARF models.

Acute Kidney Injury↗
PubMed1997

Inhibition of PAH transport by parathyroid hormone in OK cells: involvement of protein kinase C pathway.

We have previously shown that the p-aminohippurate (PAH) transport system in OK kidney epithelial cell line is under the regulatory control of protein kinase C. Parathyroid hormone (PTH) could activate protein kinase C, as well as protein kinase A, in OK cells. In the present study, the effect of PTH on PAH transport was studied in OK cells. PTH inhibited the transcellular transport of PAH from the basal to the apical side, as well as the accumulation of PAH in OK cells. Basolateral PAH uptake was inhibited by PTH in a dose- and time-dependent manner. Protein kinase A activators did not affect the transcellular transport or the accumulation of PAH. The PTH-induced inhibition of the accumulation of PAH was blocked by a protein kinase C inhibitor staurosporine. These results suggest that PTH inhibits the PAH transport in OK cells and that the messenger system mediated by protein kinase C, not protein kinase A, plays an important role in the regulation of PAH transport by PTH.

1-Methyl-3-isobutylxanthine↗
PubMed1997

Recognition of beta-lactam antibiotics by rat peptide transporters, PEPT1 and PEPT2, in LLC-PK1 cells.

PEPT1 and PEPT2 are H(+)-coupled peptide transporters expressed preferentially in the intestine and kidney, respectively, which mediate uphill transport of oligopeptides and peptide-like drugs such as beta-lactam antibiotics. In the present study, we have compared the recognition of beta-lactam antibiotics by LLC-PK1 cells stably transfected with PEPT1 or PEPT2 cDNA. Cyclacillin (aminopenicillin) and ceftibuten (anionic cephalosporin without an alpha-amino group) showed potent inhibitory effects on the glycylsarcosine uptake in the PEPT1-expressing cells. Other beta-lactams, such as cephalexin, cefadroxil, and cephradine (aminocephalosporins), inhibited modestly the PEPT1-mediated glycylsarcosine uptake. Except for ceftibuten, these beta-lactams showed much more potent inhibitions on the glycylsarcosine uptake via PEPT2 than via PEPT1. Comparison of the inhibition constant (Ki) values between cefadroxil and cephalexin suggested that the hydroxyl group at the NH2-terminal phenyl ring increased affinity for both PEPT1 and PEPT2. It is concluded that PEPT2 has a much higher affinity for beta-lactam antibiotics having an alpha-amino group than PEPT1 and that substituents at the NH2-terminal side chain of these drugs are involved in the recognition by both peptide transporters.

Animals↗
PubMed1997

[The studies of extracorporeal shock wave lithotripsy (ESWL) for pancreatic ductal stones].

30 patients with main pancreatic duct stones were treated by ESWL. In 18 of 22 patients who had not previously undergone endoscopic pancreatic sphincterotomy (EPST) or endoscopic sphincterotomy (EST), the stone fragments disappeared after ESWL. The fragments were removed endoscopically in the remaining 4 cases. Complete clearance was achieved in 8 cases with endoscopically unextractable stones by ESWL. After the ESWL procedure, absolute relief from pain was reported by in 19 of 22 patients with abdominal complaints. Serum amylase levels decreased significantly, and dilatation of the main pancreatic duct (MPD) was reduced. In the medium-term follow-up period, pancreatic exocrine function and endocrine function had a possibility to be preserved. One case of pancreatic cancer and one case of an intraductal papillary tumor of the pancreas were found, indicating that careful observation is necessary even after complete removal of pancreatic stones. In cases of Santorini duct dominant, multiple stones, or stricture of the MPD, ESWL should be combined with EPST and endoscopic stenting for preventing recurrence of acute pancreatitis and pancreatic stones. In conclusion, ESWL is the first choice of treatment for pancreatolithiasis and useful procedure and the limited complications.

Adult↗
PubMed1997

Characterization of stably transfected kidney epithelial cell line expressing rat H+/peptide cotransporter PEPT1: localization of PEPT1 and transport of beta-lactam antibiotics.

We established stably transfected LLC-PK1 cells expressing the rat H+/peptide cotransporter PEPT1 (designated LLC-rPEPT1) and examined membrane localization and uptake by rat PEPT1 of oral beta-lactam antibiotics. The LLC-rPEPT1 cells expressed a novel PEPT1 protein with an apparent molecular mass of 75 kdaltons, which was found in rat intestinal membranes. The cell surface biotinylation of LLC-rPEPT1 cell monolayers grown on membrane filters showed that PEPT1 was localized predominantly on the apical membranes and, to a lesser extent, on the basolateral membranes. The amount of [14C]glycylsarcosine uptake in LLC-rPEPT1 cell monolayers was 3-fold greater from the apical, than from the basolateral side, which suggested that rat PEPT1 expressed on both membranes was functionally active. LLC-rPEPT1 cells grown on plastic dishes transported differently charged oral cephalosporins such as ceftibuten (divalent anion lacking an alpha-amino group) and cephradine (zwitterion with an alpha-amino group) in the presence of an inward H+ gradient, whereas those transfected with the vector alone did not have transport activity. Kinetic analysis revealed that the LLC-rPEPT1 cells had much higher affinity for ceftibuten than for cephradine. Di- and tripeptides and bestatin, a dipeptide-like antineoplastic drug, potently inhibited the uptake of these cephalosporins. These results suggest that the LLC-rPEPT1 cells serve as a useful model with which to analyze the mechanisms involved in membrane targeting and substrate recognition by rat PEPT1.

Animals↗
PubMed1996

Cholesterol modulates organic cation transport activity and lipid fluidity in rat renal brush-border membranes.

The role of cholesterol in organic cation transport was studied in rat renal brush-border membranes. H+ gradient-dependent uptake of the organic cation tetraethylammonium in brush-border membrane vesicles was stimulated by cholesterol enrichment in a dose-dependent manner. The dissipation rate of the H+ gradient, a driving force for organic cation transport in brush-border membranes, was reduced by cholesterol enrichment. Tetraethylammonium uptake in the absence of H+ gradient was also stimulated by cholesterol enrichment. These findings indicate that cholesterol modulates tetraethylammonium uptake by affecting the intrinsic activity of the organic cation transporter and the H+ gradient dissipation rate. Therefore, cholesterol content should be an important determinant for organic cation transport in renal brush-border membranes.

Animals↗
PubMed1996

cDNA cloning and functional expression of a novel rat kidney organic cation transporter, OCT2.

A cDNA encoding a novel organic cation transporter, designated as OCT2 was isolated from the rat kidney. The rat OCT2 cDNA (2,205 bp) had an open reading frame encoding for a 593-amino acid protein (calculated molecular mass of 66 kDa) which shows 67% identity with the rat OCT1. Northern hybridization and reverse transcription-PCR analyses revealed that the rat OCT2 mRNA transcript was expressed predominantly in the kidney, at higher level in the medulla than in the cortex, but this transcript was not detected in the brain, heart, lung, liver, small intestine or spleen. When expressed in Xenopus oocytes, rat OCT2 stimulated the uptake of tetraethylammonium, and the uptake was markedly inhibited by the presence of cimetidine, procainamide and quinidine. These findings suggest that OCT2 is responsible for the transport of cationic drugs in the kidney.

Amino Acid Sequence↗
PubMed1996

Molecular cloning and tissue distribution of rat peptide transporter PEPT2.

A cDNA encoding rat H(+)- coupled peptide transporter PEPT2 was isolated. The cDNA encoded a protein of 729 amino acids with 48% amino acid identity to the rat PEPT1. The mRNA expression of rat PEPT2 was predominant in the kidney. When expressed in Xenopus oocytes, rat PEPT2 stimulated the uptake of bestatin, a dipeptide-like drug.

Amino Acid Sequence↗
PubMed1996

Immuno-localization of H+/peptide cotransporter in rat digestive tract.

In the mammalian digestive tract, small peptides are absorbed by a H+-coupled peptide transport system. Using an antibody against the rat H+/peptide cotransporter (PepT1), we examined the localization of PepT1 immunohistochemically along the rat digestive tract. PepT1 was detected in the small intestine (duodenum, jejunum, and ileum), but not in the esophagus, stomach, colon, or rectum. PepT1 was especially enriched in the villi, where it was localized in the brush border of the absorptive epithelial cells. PepT1 was not detected in the mucus-secreting goblet cells or less-differentiated epithelial cells in the crypts. These observations show that PepT1 is specific to the brush border of the differentiated absorptive epithelial cells and suggest that H+-coupled uptake of small peptides and peptide-like drugs occurs at the apical membrane of these cells in the small intestine.

Animals↗
PubMed1996

Expression of epidermal growth factor and its receptor in rabbits with ischaemic acute renal failure.

Urinary immunoreactive epidermal growth factor (EGF) levels decrease, and renal immunoreactive EGF levels increase in rats with ischaemic acute renal failure (ARF). We investigated the immunohistochemical localization of EGF and EGF receptor in rabbits with ischaemic ARF to clarify the significance of renal EGF. Male New Zealand White rabbits underwent right nephrectomy prior to a 60 min renal artery clamp. At 3, 6, 24, 48, 72 and 96 h after ischaemia, serum urea nitrogen and serum creatinine were determined. Guinea pig anti-rabbit EGF antibody and monoclonal anti-EGF receptor antibody were used for the primary incubation. EGF was immunolocalized to the ascending limb of Henle and the distal convoluted tubule in the normal right kidneys. However, in the post ischaemic left kidneys at 6, 24, 48 and 72 h, immunoreactivity of EGF was associated with proximal tubules. In the normal kidneys, antibody to EGF receptor reacted with distal tubules and collecting ducts. In the ischaemic kidneys, EGF receptor was localized in the basolateral membrane in the proximal tubules. The expression of EGF and EGF receptor in renal tubules may play an important role in repair following ischaemic renal damage.

Acute Kidney Injury↗