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Biomedical subjects

K Takeuchi

Publications and source records attributed to K Takeuchi.

At least 559 records · Page 31Linked to original sources
PubMed1996

Intrarenal mRNA expression of the rat MDCK-type chloride channel.

We have reported the isolation of a rat cDNA for MDCK-type chloride channel (RKCL) which is expressed in many tissues including the kidney. In the present study, intrarenal expression distribution of RKCL mRNA and the effect of dehydration on its expression were examined. In situ hybridization showed that RKCL mRNA is more abundantly expressed in the renal medulla and papilla than in the cortex. Reverse transcription and polymerase chain reaction using microdissected nephron segments showed that RKCL mRNA is expressed in several nephron segments, notably the ascending thin limb of Henle's loop and inner medullary collecting duct. Under dehydration, renal RKCL mRNA expression level was not significantly changed for 5 days. In conclusion, RKCL mRNA is expressed in most nephron segments, playing a role in the renal tubular chloride ion homeostasis.

Animals↗
PubMed1996

Diethyldithiocarbamate, a superoxide dismutase inhibitor, reduces indomethacin-induced gastric lesions in rats.

We examined the effect of diethyldithiocarbamate (DDC), the superoxide dismutase (SOD) inhibitor, on the development of gastric lesions induced by indomethacin in rats. Indomethacin (25 mg/kg) was given subcutaneously, and gastric acid secretion, motility, lipid peroxidation, vascular permeability, and myeloperoxidase as well as gastric lesions were measured. Indomethacin produced high-amplitude contractions of the stomach and caused hemorrhagic lesions in the corpus mucosa with significant increase in neutrophil-related processes such as myeloperoxidase activity, vascular permeability and lipid peroxidation. These changes caused by indomethacin were all significantly inhibited by prior administration of atropine (3 mg/kg s.c.). Pretreatment of the animals with DDC (75-1,000 mg/kg s.c.) prevented these lesions induced by indomethacin in the corpus mucosa in a dose-dependent manner (> 100 mg/kg), though at high doses (> 750 mg/kg) some damage was found in both the antrum and duodenum. DDC showed a significant inhibition against the gastric mucosal SOD activity (> 400 mg/kg), yet potently suppressed the increase of lipid peroxidation, vascular permeability, and myeloperoxidase activity caused by indomethacin. DDC dose-dependently (> 75 mg/kg) inhibited the enhancement of gastric motility caused by indomethacin and showed a weak antisecretory effect at high doses (> 750 mg/kg). These results showed that DDC reduced indomethacin-induced gastric lesions by suppressing gastric motility, despite inhibiting SOD activity. This study also indicates the prime importance of gastric hypercontraction in the pathogenesis of this lesion model and suggests that other events including the neutrophil-related processes may be secondary to gastric hypercontraction caused by indomethacin.

Animals↗
PubMed1996

Comparison of surface antigens on eosinophils from patients with eosinophilia.

Recent studies have suggested that there may be heterogeneity among human eosinophils. To study this further, surface antigens on blood eosinophils from patients with eosinophilia (23 bronchial asthma, 6 eosinophilic pneumonia, 1 Kimura's disease and 1 adult T-cell leukemia) and from 8 control subjects were examined using a new direct method for fluorescence detection of eosinophils. HLA-DR+ and CD4+ eosinophil counts were higher in patients with bronchial asthma and adult T-cell leukemia (ATL) than in patients from other groups and in control subjects. CD11b+ eosinophil counts in Kimura's disease and ATL were smaller than those in the other groups. CD45RO+ eosinophil counts in bronchial asthma and eosinophilic pneumonia were significantly higher (p < 0.05) compared with Kimura's disease, ATL and control subjects. CD44+ eosinophil counts in eosinophilic pneumonia were significantly higher (p < 0.05) compared with the other groups and control subjects. These results suggest the existence of functional heterogeneity in the different eosinophilic diseases, with eosinophils in bronchial asthma and eosinophilic pneumonia being more highly activated in migration, activation and immunoregulation. On the other hand, eosinophils in Kimura's disease and ATL might be functionally down-regulated. This heterogeneity of eosinophils may reflect differences in the pathogenesis of various eosinophilic diseases.

Adolescent↗
PubMed1996

Fluoride concentrations and distribution in premolars of children from low and optimal fluoride areas.

We have compared the fluoride (F) concentrations from the enamel surface to the dentino-enamel junction (DEJ), and through dentine to the dentino-pulpal junction (DPJ) in premolars extracted from school children in Chemnitz (former Karl-Marx-Stadt), Germany (F: 1.0 ppm in the water supply), Erfurt, Germany (F: 0.2 ppm in the water supply) and Nagoya, Japan (F: 0.1 ppm in the water supply). In teeth from children in Cheminitz, Erfurt and Nagoya, the profiles of F distribution using an abrasive microsampling technique revealed high F concentrations in the enamel surface, with a substantial decrease towards a plateau in the interior. In dentine the F concentrations were higher than in enamel, and also decreased to a plateau from the DEJ, thereafter increasing considerably towards the DPJ. F concentrations at any depth in the enamel and dentine of teeth from Chemnitz were 2-3 times higher than those in Erfurt and Nagoya. There was no significant difference in F concentrations or distributions between Erfurt and Nagoya. Close to the DEJ in both enamel and dentine as well as the enamel surface and the DPJ side of dentine, higher F concentrations were observed in Chemnitz compared with Erfurt and Nagoya.

Adolescent↗
PubMed1996

Analysis of T cell receptor beta chain repertoire in middle ear effusions.

In order to elucidate the immune response in otitis media with effusion (OME), the polymerase chain reaction was employed to examine T cells in middle ear effusions in patients with OME for utilization of T cell receptor (TCR) variable region genes. Specimens of RNA were extracted from 13 ears of 12 patients (9 children and 3 adults). Oligonucleotide primers specific for individual TCR Vbeta gene families were used to amplify TCR gene products in each sample. Although the number of Vbeta families utilized by each sample varied from 1 family to 21, a few significant trends emerged. Eleven ears out of 13 expressed Vbeta7, which was the most frequently utilized (84.6%) Vbeta family among the 24 Vbeta families. In 5 of the 13 samples, the number of Vbeta families utilized was restricted to 1, which was Vbeta7 in all 5 samples. This result indicates the possibility that Vbeta7-bearing T cells in the middle ear are responding to a certain common antigen in some cases of OME.

Adolescent↗
PubMed1996

Dendritic cells: a novel cellular component of the rat incisor enamel organ appearing in the late stages of enamel maturation.

Immunocompetent cells in the enamel organ of rat incisors were examined immunohistochemically using OX6, ED1, and ED2 monoclonal antibodies known to recognize the Class II MHC molecules, a monocyte-macrophage lineage, and residential macrophages, respectively. The OX6 immunopositive cells (MHC cells) were located exclusively in the enamel maturation zone. MHC cells increased in number in the incisal direction and occasionally extended cytoplasmic processes deep into the ameloblast layer. Migration of MHC cells in the ameloblast layer were also encountered. MHC cells lacked phagolysosomes and could be distinguished from typical macrophages. ED2 immunopositive cells were not seen in the enamel organ. ED1 positive cells displayed identical localization to MHC cells except that some appeared in the transitional zone. MHC cells could not be seen in the enamel organ of rat molar tooth germs. Our data confirmed the presence of a large population of "dendritic" immunocompetent cells in the enamel organ of rat incisors and characterized the ultrastructural features of these cells. Biological significance of the immunocompetent cells in the enamel organ during amelogenesis needs to be clarified.

Amelogenesis↗
PubMed1996

Expression of a CD44 variant containing exons 8 to 10 is a useful independent factor for the prediction of prognosis in colorectal cancer patients.

PURPOSE: To determine the expression of the CD44 variant containing a variant exon 8 to 10 product (CD44v8-10) in colorectal cancer and to evaluate its prognostic value. MATERIALS AND METHODS: CD44v8-10 was studied in resected tumors and normal mucosae obtained from 215 colorectal cancer patients (118 colon cancer and 97 rectal cancer). The expression of CD44v8-10 was analyzed immunohistochemically using the anti-CD44v8-10 monoclonal antibody (mAb) 44-1V. RESULTS: One hundred of 215 cancer tissues expressed CD44v8-10. Positive staining was intense mainly on the cell membranes. There was no significant correlation between expression of CD44v8-10 and histologic type, primary tumor, lymphatic invasion, venous invasion, or peritoneal invasion. There were significant correlations between CD44v8-10 immunoreactivity and both lymph node and hematogenous metastasis. Patients with CD44v8-10-positive tumors had a greater relative risk of death compared with those whose tumors were CD44v8-10-negative. Among 169 patients who underwent curative resection, CD44v8-10 expression correlated with a high recurrence rate. The 5- and 10-year survival rates were 90.3% of patients with CD44v8-10-negative tumors, and 72.1% and 58.0% of those with CD44v8-10-positive tumors, respectively; these differences between the two groups of patients were significant (P < .01). In multivariate analysis using the Cox regression model, CD44v8-10 expression emerged as an independent prognostic indicator. CONCLUSION: The results suggest that CD44v8-10 plays a role in metastasis of colorectal cancer, and tha CD44v8-10 expression may be a biologic marker of prognostic significance.

Antibodies, Monoclonal↗
PubMed1996

Immunolocalization of rat thromboxane receptor in the kidney.

Thromboxane (TX) is a vasoactive hormone which is known to be involved in renal physiology and pathophysiology. To identify the site of action of TX in the kidney, we examined the distribution of this receptor in the normal rat kidney using a polyclonal antibody against TX receptor we had raised. Western immunoblot of rat kidney membrane fractions with the antibody identified a single protein band at the predicted molecular mass of rat TX receptor protein. In the rat kidney, immunostainable TX receptor was observed in glomeruli, arterial walls, luminal membranes of thick ascending limbs of Henle's loop, the luminal and basolateral membranes of either distal convoluted tubules or connecting tubules, and the basolateral membranes of collecting tubules. The localization of TX receptor provides better understanding of the mechanism of previously reported effects of TX on glomerular and tubular functions leading to hypertension as well as renal parenchymal diseases.

Animals↗
PubMed1996

Association of a mutation in thiazide-sensitive Na-Cl cotransporter with familial Gitelman's syndrome.

Gitelman's syndrome is a variant of Bartter's syndrome, characterized by hypokalemia, hypomagnesemia, hypocalciuria, and hypovolemia. We have observed familial cases of Gitelman's syndrome, and a possible mutation in thiazide-sensitive Na-Cl cotransporter was investigated in this kindred. The proband was a 47-yr-old Japanese female, and her mother was also affected. Her parents and maternal grandparents are consanguineous. By using PCR-amplification and direct sequencing, we identified a novel non-conservative missense mutation at 623 amino acid position, which substitutes proline for leucine (L623P), and also creates an Nci I restriction site in the exon 15. The mutation was not detected in normal healthy subjects (n = 102). Nci I digestion of PCR-amplified exon 15 DNA fragments from individuals in the family indicated the autosomal recessive inheritance of the disorder. In conclusion, the L623P mutation in the thiazide-sensitive Na-Cl cotransporter gene is suggested to impair the transporter activity, and to underlie this familial Gitelman's syndrome; Gitelman's syndrome observed in this kindred has been inherited in an autosomal recessive fashion.

Bartter Syndrome↗
PubMed1996

[Gastroduodenal bicarbonate secretion: pharmacological modulation and contribution to mucosal protection].

Bicarbonate secretion from the surface epithelial cells of the gastroduodenal mucosa is an active process depending upon the tissue metabolism and plays an important role as the first line of defense in mucosal protection in collaboration with the mucus gel. This secretion is regulated by humoral and neural factors as well as endogenous prostaglandins (PGs) and is considered to be intracellularly mediated by cyclic AMP in the duodenum and by cyclic GMP in the stomach. Ca2 also acts as an intracellular mediator in this process. This bicarbonate secretion is markedly increased in response to luminal acid, mediated by PGs and neural factors including capsaicin-sensitive sensory nerves, and the impairment of this response is involved in the pathogenesis of various duodenal ulcer models induced by cysteamine, nonsteroidal antiinflammatory drugs and stress. The mechanisms underlying the mucosal protection by HCO3 secretion is two fold; One is the direct neutralization of H + in the lumen, and the other is the establishment of a pH gradient across the mucus gel aided by the physico-chemical property of the mucus. However, the cellular mechanisms of HCO3 secretion, including the receptors, the mediators and the signal transduction pathway have been poorly understood. The establishment of a method for preparing isolated epithelial cells and the probe for HCO3 secretion in isolated cells is required to further elucidate the mechanism of HCO3 secretion.

Animals↗
PubMed1996

cDNA cloning and expression of the Xenopus homologue of the neural adhesion molecule, contactin (F3/F11).

Contactin (F3/F11) is an immunoglobulin superfamily cell surface glycoprotein predominantly expressed in the nervous system. To examine the structure and tissue distribution of Xenopus contactin, a cDNA clone was isolated based on the amino acid sequences conserved among chicken and mammalian contactin proteins. The conceptual translate of the cDNA consists of 1005 amino acid residues that have 70% identity to those of chicken and mammalian contactin. Northern blot hybridization using a labeled cDNA fragment revealed specific expression of 6.5 kb mRNA in the brain. Monoclonal and polyclonal antibodies prepared to the recombinant Xenopus contactin peptides detected a single 135 kD band on Western blots of the brain and spinal cord extracts. Differential extraction and phosphatidylinositol-specific phospholipase C (PI-PLC) digestion experiments showed that the immunoreactive 135 kD proteins bind, at least in part to the membrane by GPI anchor. On brain tissue sections, strong contactin immunoreactivities were detected on nerve fibers of a subset of cerebral and cerebellar neurons. These results suggest that the basic structure and tissue distribution of Xenopus contactin are similar to those in other vertebrates.

Amino Acid Sequence↗
PubMed1996

Attenuation of intrinsic active tone by endothelium-derived nitric oxide in aortae of spontaneously hypertensive rats with different levels of blood pressure.

The influences of endothelium on the basal tone of aortae from various strains of spontaneously hypertensive rats with different blood pressure (SHR, SHRSP, M-SHRSP) were studied. Endothelium-intact preparations of aortae from spontaneously hypertensive rats exhibited spontaneous active tone, which was greater in the order of SHR < SHRSP < M-SHRSP. The active tone of the M-SHRSP preparations was about 40% of high-K(+)-induced contraction, while that of normotensive WKY was less than 5%. The active tone was enhanced by the removal of endothelium. The active tone was sensitive to extracellular Ca2+ and abolished by verapamil. The application of N(G)-monomethyl-L-arginine caused the increase in the active tone which was counteracted by L-arginine. These results indicate that the active tone of smooth muscle increases as the blood pressure of the rat increases, and that endothelium attenuates the active tone by releasing nitric oxide (NO) spontaneously. It was also demonstrated that the attenuating action of endothelium was impaired depending on the blood pressure level.

Animals↗
PubMed1996

Establishment of cell lines stably expressing mumps virus glycoproteins.

We established two cell lines that stably express hemagglutinin-neuraminidase (HeLa-HN) and fusion proteins (HeLa-F) of a fusogenic strain of mumps virus. Infection of HeLa-F cells with a nonfusogenic strain resulted in induction of extensive cell fusion. On the other hand, HeLa-HN cells appeared resistant to cell fusion induced by mumps virus infection.

Animals↗
PubMed1996

[Successful neoadjuvant chemotherapy in a patient with advanced gastric cancer with periaortic lymph node metastasis].

We described a case of advanced gastric cancer accompanied by metastasis to the periaortic lymph node. Two cycles of the neoadjuvant chemotherapy consisting of 5-FU and low-dose CDDP (FP therapy) were given. 5-FU (800mg/body/day) was administered as a continuous intravenous infusion for five days, and CDDP (10mg/body/day) was given as an intravenous infusion for an hour on days 1-5. The FP therapy resulted in a significant effect in the metastatic periaortic lymph node. Then, total gastrectomy with combined resection of spleen was done. Histological examination of the resected specimen revealed the histological effect showing Grade 3 in the primary site and Grade 2 in the periaortic lymph node. The patient is alive with no evidence of recurrence 13 months after operation. Thus, FP therapy is thought to be effective against advanced gastric cancer.

Aged↗
PubMed1996

[Basic amino acid, L-arginine aggravates ischemia-reperfusion injury].

Basic amino acid, L-arginine has been known to have several biological actions including nitric oxide production. The real effects caused by L-arginine administration to heart has not been fairly understood in the setting of ischemia-reperfusion process. The effects of L-arginine on recovery of myocardial contractile function and oxidative metabolism were studied in a model of reversible global normothermic ischemic injury using an isolated, buffer-perfused rabbit heart preparation. 1 mM L-arginine or vehicle was infused into hearts for 2 minutes at the onset of 35 minutes of ischemia in L-arg. group or in control group, respectively. Oxygen consumption (MVO2), lactate release into coronary vessels, and cardiac function including developed pressure, +dp/dt, -dp/dt and diastolic pressure-volume relationship (PVR) were measured and high energy phosphates were also evaluated by 31P-NMR spectroscopy. Endothelial function was also evaluated by acetylcholine (Ach) infusion with monitoring of constant perfusion pressure. L-arginine caused a significant increase in the PVR and profund decline in systolic function when compared to control group. MVO2 was significantly impaired to cause a decrease of high energy phosphates (phosphocreatine and ATP). Lactate release into coronary vessels on reperfusion was significantly higher in L-arg group than that in control group, suggesting a promotion of anaerobic glycolysis. Deterioration of endothelial function and smooth muscle function of artery were evidenced by Ach infusion test. Although the mechanisms of injury are speculatory, possible mechanisms of this injury are stimulation of nitric oxide production by L-arginine and cation change, especially calcium accumulation. We concluded that L-arginine was able to cause aggravation of ischemia-reperfusion injury with reduced contractile function and mitochondrial function and increased anaerobic glycolysis after ischemia-reperfusion in an isolated model of reversible ischemic injury.

Animals↗