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K Takata

Publications and source records attributed to K Takata.

At least 37 records · Page 2Linked to original sources
PubMed2001

Hypertonicity-induced expression of aquaporin 3 in MDCK cells.

Aquaporins (AQPs) are water channel proteins that participate in water transport. In the principal cells of the kidney collecting duct, water reabsorption is mediated by the combined action of AQP2 in the apical membrane and both AQP3 and AQP4 in the basolateral membrane, and the expression of AQP2 and AQP3 is regulated by antidiuretic hormone and water restriction. The effect of hypertonicity on AQP3 expression in Madin-Darby canine kidney (MDCK) epithelial cells was investigated by exposing the cells to hypertonic medium containing raffinose or NaCl. Northern blot and immunoblot analyses revealed that the amounts of AQP3 mRNA and AQP3 protein, respectively, were markedly increased by exposure of cells to hypertonicity. These effects were maximal at 12 and 24 h, respectively. Immunofluorescence and immunoelectron microscopy also demonstrated that the abundance of AQP3 protein was increased in cells incubated in hypertonic medium and that the protein was localized at the basolateral plasma membrane. These results indicate that the expression of AQP3 is upregulated by hypertonicity.

Animals↗
PubMed2001

[Bowel perforation after extracorporeal shock wave lithotripsy: a case report].

A case of intestinal perforation caused by ESWL for left ureteral calculus is reported. A 69-year-old male underwent the graft replacement for bilateral iliac aneurysm in March, 1996. In February, 1999, there appeared left flank pain, and a diagnosis of left ureterolithiasis was made by radiological examination. On March 29 he was admitted to our department for ESWL. On March 30, ESWL for calculus in the pelvic region was performed with the patient in the prone position. The patient complained of the left lower abdominal pain immediately after ESWL, but no muscular defense was observed. Since the pain was not relieved, CT was performed on March 31, but no evident abnormal finding was found. Thereafter the pain continued and on April 2 muscular defense was also noted. On CT performed a second time, free air and evidence of ileus were found, so emergency operation was performed. Two perforations about 2 mm in size were found in the jejunum 130 cm from the Treitz' ligament, which led to diagnosis of intestinal perforation due to ESWL. The patient followed a satisfactory postoperative course and was discharged on April 23. There has been only one reported case of intestinal perforation due to ESWL. It is a very rare complication. However, this complication should be taken into consideration where the patient has the history of abdominal surgery and where ESWL was performed with the patient in the prone position.

Aged↗
PubMed2000

Aryl hydrocarbon receptor nuclear translocator is induced by kainic acid in rat hippocampal glial cells.

The localization and function of aryl hydrocarbon receptor nuclear translocator (ARNT) in the brain are still unclear. In this study, we examined changes of ARNT protein in rat hippocampus, by immunoblotting and immunohistochemical analysis using anti-ARNT antibody. Treatment of kainic acid (KA) induced marked increase in ARNT protein in both cytosolic and organellar fractions. ARNT immunoreactivity was markedly increased, predominantly in microglia and partly in astrocytes, similar to the immunoreactivity of heme oxygenase-1. In contrast, protein level of dioxin receptor did not change and hypoxia-inducible factor-1alpha protein was undetectable. These results suggest that ARNT expression in glial cells may participate in KA-induced episodes in the hippocampus.

Animals↗
PubMed2000

Increase of bcl-2 protein in neuronal dendritic processes of cerebral cortex and hippocampus by the antiparkinsonian drugs, talipexole and pramipexole.

Treatment of rats for 4 days with the antiparkinsonian drugs, talipexole and pramipexole, markedly increased Bcl-2 immunoreactivity in neuronal dendritic processes in both cerebral cortex and hippocampus, but treatment for 1 day with either of these drugs did not. Repeated administration of talipexole or pramipexole may have neuroprotective effect in neurodegenerative disorders.

Animals↗
PubMed2000

Actin filaments play a critical role in insulin-induced exocytotic recruitment but not in endocytosis of GLUT4 in isolated rat adipocytes.

Actin-based cytoskeletons have been implicated in insulin-stimulated glucose transport and translocation of the insulin-regulated glucose transporter, GLUT4, from the intracellular pool to the plasma membrane. However, most previous studies were done using adherent cell systems such as L6 myotubes and 3T3-L1 adipocytes, and very little information is available on the significance of the actin filaments to the insulin action in isolated adipocytes, a widely used experimental system. In the present study, we investigated the physiological role of actin filaments in the subcellular trafficking of GLUT4 in isolated rat adipocytes. We first compared the effects of two actin-disrupting reagents, latrunculin A and cytochalasin D, on the organization of the actin filaments as well as on the insulin action on glucose transport by laser confocal microscopy combined with biochemical analysis of the insulin action. Treatment of the cells with latrunculin A induced dose- and time-dependent disappearance of the filamentous actin, which correlated very well with inhibition of the insulin effect on glucose transport. Although cytochalasin D at 50 microM significantly inhibited insulin-stimulated glucose transport, it was not effective in disassembly of the actin filaments; rather, many intense punctate signals were observed in cytochalasin D-treated cells. In the actin-disrupted adipocytes treated with latrunculin A, insulin-induced GLUT4 translocation was inhibited completely. In addition, latrunculin A remarkably inhibited both insulin-induced glucose transport and GLUT4 translocation in the presense of D(k)-(62-85), a potent inhibitor of GLUT4 endocytosis, suggesting that intactness of the actin filaments was necessary for insulin-induced exocytosis of the GLUT4-containing vesicles. On the other hand, latrunculin A showed little inhibitory effect on either endocytosis of the trypsin-cleaved 35-kDa fragment of GLUT4 or decay of the glucose transport activity after addition of wortmannin in insulin-stimulated cells. The results of our experiment show clearly that, in rat adipocytes, (i) latrunculin A may be a more suitable tool than cytochalasin D for disruption of actin filaments, and (ii) actin filaments play a crucial role in exocytotic recruitment of GLUT4 to the plasma membrane from the intracellular pool, but not in its endocytosis.

Actins↗
PubMed2000

Differential localization of organic cation transporters rOCT1 and rOCT2 in the basolateral membrane of rat kidney proximal tubules.

Organic cation transporters play an important role in the secretion of cationic drugs as well as endogenous cationic metabolites in the renal tubules. Immunoblotting showed the presence of organic cation transporter proteins, rOCT1 and rOCT2, in the rat kidney. By immunofluorescence microscopy, rOCT1 was shown to be concentrated in the proximal tubules in the renal cortex. rOCT2, on the other hand, was rich in the proximal tubules in the outer stripe of the outer medulla. Confocal microscopy revealed that both rOCT1 and rOCT2 were localized to the basolateral membranes of these tubule cells. These findings directly show that rOCT1 and rOCT2 are basolateral membrane proteins and are differentially distributed along the proximal tubules.

Animals↗
PubMed2000

CAAT sites are required for the activation of the H. pulcherrimus Ars gene by Otx.

A product of sea urchin homologues of the Drosophila orthodenticle gene, HpOtxL has been implicated as a transcription activator of the aboral ectoderm-specific arylsulfatase (Ars) gene during early development of the sea urchin embryo. Using an in vivo transactivation system, we present evidence that HpOtxL activates the target gene by interacting with co-factors. Otx binding sites alone have little effect on the activity of an Ars promoter, but when both Otx binding sites and CAAT sequences are present in the enhancer region of Ars, the fragment shows a high enhancer activity. A gel mobility shift assay reveals that a nuclear protein binds to the CAAT sequences present near the Otx binding sites in the enhancer region of Ars. The activation domain of HpOtxL resides in the C terminal region between amino acids 218 and 238. The N-terminal region is responsible for the enhancement of transactivation of the Ars promoter, although the region itself does not function as an activation domain. HpOtxE, which possesses an N-terminal region different from HpOtxL, does not activate the Ars promoter even in the presence of CAAT sequences. Together with previous findings, our results suggest that Otx regulates different genes by interacting with different co-factors in sea urchin development.

Animals↗
PubMed2000

Radiation-induced brain calcification: paradoxical high signal intensity in T1-weighted MR images.

BACKGROUND: Irradiation to the central nervous system (CNS) in childhood is known to induce cerebral calcification after a latent period. Calcification has been generally found to show nil or a reduction in signal intensity in magnetic resonance (MR) images. However, we have studied three patients with radiation-induced brain calcification, who manifested increased signal intensity on T1-weighted MR images. METHOD: Three girls had each been diagnosed as having a suprasellar germ cell tumour and were treated with conventional fractionated radiotherapy in their childhood. In one case, chemotherapy was given prior to the CNS irradiation. FINDINGS: All three patients survived their disease, and a follow-up CT scan revealed calcification in the brain, which has shown an increased signal intensity in the T1-weighted images of MR. INTERPRETATION: Cerebral calcification may be presented as a high signal intensity in the T1-weighted MR images. This may be explained by a surface-relaxation effect by the calcium salt particle, precipitated in the brain due to radiation-induced mineralising microangiopathy.

Adolescent↗
PubMed2000

Ciliogenesis and ciliary abnormalities.

Cilia are motile processes extending from the basal bodies, playing important roles in the mucociliary clearance in the respiratory tract and the transport of the ovum from the ovary to the uterus in mammals. Ciliogenesis is divided into four stages: (1) duplication of centrioles; (2) migration of centrioles to the apical cell surface to become basal bodies; (3) elongation of cilia containing the axoneme; and (4) formation of accessory structures of basal bodies. The orderly course of ciliogenesis appears to be disturbed by various internal and external factors and, as a result, various unusual forms of the ciliary apparatus develop in the cell. Inhibition of basal body migration results in development of intracytoplasmic axonemes, cilia within periciliary sheaths, and intracellular ciliated cysts. Swollen cilia and the bulging type of compound cilia are formed during ciliary budding and elongation. This review also discusses the origin, composition, and function of the centriolar precursor structures.

Animals↗
PubMed2000

Localization of gamma-tubulin to the basal foot associated with the basal body extending a cilium.

The human oviduct epithelium primarily consists of ciliated cells and secretory cells. Solitary cilia usually extend from the apical surface of the secretory cells. We investigated the localization of gamma-tubulin in the ciliary basal apparatus of both cell types by fluorescence immunohistochemistry and immunoelectron microscopy. In addition to basal bodies, gamma-tubulin was identified in the lateral basal foot, especially the basal foot cap. This observation is consistent with previous observations that microtubules radiate from the basal foot and the basal foot serves as the microtubule organizing centre.

Cilia↗
PubMed2000

[Recurrent spontaneous rupture of the urinary bladder: a case report].

The patient was a 67-year-old woman who had undergone radical hysterectomy and postoperative radiotherapy for cervical cancer at the age of 46 years. Spontaneous rupture of the urinary bladder occurred twice in 1997, and conservative treatment was performed on each occasion. She was admitted to our hospital for the third time of spontaneous rupture of the urinary bladder. She underwent bilateral cutaneous ureterostomy because of panperitonitis and paralytic ileus. A review of 11 cases of recurrent rupture of the urinary bladder reported in Japan including the present case revealed that, patients who had been conservatively treated tended to be subject to recurrence. However, the risk of recurrence remains when a partial cystectomy is performed. Therefore, especially in recurrent cases, augmentation cystoplasty or urinary diversion should be considered as the treatment for spontaneous rupture of the urinary bladder due to radiation cystitis.

Aged↗
PubMed2000

[A case report of skeletal muscle metastasis of renal cell carcinoma effectively treated with interferon-alpha].

The skeletal muscle is a very rare site of metastasis in renal cell carcinoma. We report the third case of skeletal muscle metastasis of renal cell carcinoma effectively treated with interferon-alpha. The patient was a 74-year-old woman who had undergone radical nephrectomy on the left side for renal cell carcinoma on April 23, 1990, and had been observed as an outpatient. In June 1997, she was admitted with a diagnosis of metastasis in the left great adductor muscle and right sixth rib, as well as multiple lung metastasis. The metastatic lesion in the great adductor muscle decreased in size by more than 50% following concomitant intramuscular administration of natural interferon-alpha (nIFN-alpha). In the other metastatic lesions, nIFN-alpha-sensitive and resistant metastatic foci were intermingled. Thus, the primary focus in the present study was presumably composed of several clones with different sensitivities to nIFN-alpha.

Aged↗
PubMed1999

Kainic acid-induced inducible cyclooxygenase and c-Jun phosphorylation in the rat hippocampal formation.

Inducible cyclooxygenase (COX-2) was transiently induced in the neurons throughout the entire hippocampus between 6 and 24 h after injection of kainic acid (KA). The induction of COX-2 correlated more closely with the induction of c-Jun than with that of c-Fos. Phosphorylated c-Jun was induced 6-12 h after in the CA3 pyramidal neurons, which undergo apoptosis. Almost all of neurons with phosphorylated c-Jun were colocalized with COX-2. These results suggest that COX-2 and c-Jun phosphorylation may participate in KA-induced neurodegeneration.

Animals↗
PubMed1999

Immuno-localization of sulphonylurea receptor 1 in rat pancreas.

AIMS/HYPOTHESIS: A sulphonylurea receptor, SUR1, and an inward rectifier potassium channel, Kir6.2, reconstitute the ATP-sensitive K(+) channel that mediates glucose-induced insulin secretion in pancreatic beta cells. We reported previously that Kir6.2 were localized at insulin-, glucagon-, and somatostatin-producing cells. In this new study we aimed to determine the distribution of SUR1 in rat pancreatic islets and to suggest the location of the ATP-sensitive K(+) channels in the islet. METHODS: Western blot analysis was carried out using two anti-SUR1 antibodies, which had been raised against different portions of rat SUR1. SUR1, Kir 6.2, and islet hormones were then localized by indirect immunofluorescence staining of the cryosections of rat pancreas. RESULTS: In Western blot analysis, each of the anti-SUR1 antibodies detected a band at 140 kDa, which is close to the predicted molecular weight of SUR1, in the homogenate of isolated pancreatic islets. Double immunofluorescence staining of cryosections showed that SUR1 occurred all over the islets, and that SUR1 colocalized with insulin, glucagon, somatostatin, and pancreatic polypeptide. Kir6.2 was also shown to be present in pancreatic polypeptide cells. CONCLUSION/INTERPRETATION: Together with our previously reported data, the above findings indicate that K(ATP) channels comprising SUR1 and Kir6.2 occur not only in beta cells but also in the alpha, delta, and pancreatic polypeptide cells of the pancreatic islets, suggesting that therapeutic sulphonylureas could act on these cells directly. [Diabetologia (1999) 42: 1204-1211]

ATP-Binding Cassette Transporters↗