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Biomedical subjects

T Takeuchi

Publications and source records attributed to T Takeuchi.

At least 127 records · Page 7Linked to original sources
PubMed2001

Interventional treatment for fetus and newborn infant with congenital heart disease.

BACKGROUND: Catheter intervention has become popular not only in adult patients but in younger patients with congenital heart disease. The early neonatal catheter interventional treatment has also been attempted in conjunction with the development of prenatal diagnosis of the congenital heart disease. METHOD: Recent articles concerning several severe structural cardiac diseases in newborns, such as critical aortic stenosis, complete transposition of the great arteries, premature constriction of the ductus arteriosus, and pulmonary stenosis or atresia with intact ventricular septum are introduced with consideration. RESULTS: This study investigated our own experiences of early neonatal balloon valvuloplasty in a patient with critical aortic stenosis carried out immediately after the delivery following prenatal diagnosis. A case with prenatal diagnosis of premature constriction of ductus arteriosus which could prevent persistent pulmonary hypertension of the newborn by early delivery at 39 weeks and 1 day of gestation were reported. CONCLUSION: Several cardiac interventional treatments performed in the present time during the perinatal period and some prospects in the near future are described in the discussion.

Angioplasty, Balloon↗
PubMed2001

Long-term outcome of endoscopic biopsy and subsequent nephroureterectomy for upper urinary tract tumor.

BACKGROUND: Upper urinary tract tumors can be biopsied using a flexible ureterorenoscope. This study examined retrospectively possible adverse effects of this procedure on patient outcome. METHODS: The study subjects consisted of 16 consecutive patients with renal pelvic tumor (n = 13) and upper ureteral tumor (n = 3). All subjects underwent endoscopic biopsy of their tumor and subsequent total nephroureterectomy between 1989 and 1995. The follow-up period ranged from 4.1 to 9.5 (mean 5.2) years. RESULTS: The overall 5-year survival rate was 87.0%, being 100% in 12 patients with tumors of grade 1 or 2. In contrast, of four patients with grade 3 tumor, three (75%) developed systemic lymphogenous and/or multiple lung metastases within 1 year postoperatively. CONCLUSIONS: The excellent patient outcomes deny any adverse effect of endoscopic biopsy on patients with grade 1 or 2 tumor. However, the endoscopic procedure should be performed prudently when a high grade tumor is suspected.

Aged↗
PubMed2001

TGF-alpha inhibits apoptosis of murine gastric pit cells through an NF-kappaB-dependent pathway.

BACKGROUND AND AIMS: Recently, some growth factors have been shown to play roles not only as growth factors but also as cell-surviving factors. Transforming growth factor (TGF)-alpha is expressed in normal gastric mucosa. In this study, we investigated the cell-surviving effect of TGF-alpha on gastric mucosal cells and its signaling mechanism. METHODS: We used a gastric mucosal cell line, GSM06, and gastric cancer cell line, AGS. Apoptosis was induced by serum depletion or exposure to sodium butyrate. Analysis of apoptosis was performed by DNA ladder assay, measuring the DNA fragmentation ratio (Burton method), and 4',6-diamidino-2-phenylindole staining. RESULTS: TGF-alpha protected gastric mucosal cells against apoptosis induced by serum depletion or sodium butyrate in a dose-dependent manner. This antiapoptotic effect of TGF-alpha was blocked by the pretreatment with reagents that can potentially inhibit NF-kappaB activation, whereas neither MEK inhibitor PD098059 nor PI-3-kinase inhibitor wortmannin abolished this effect. Electrophoretic mobility shift assay showed nuclear factor kappaB (NF-kappaB) activation by TGF-alpha stimulation. TGF-alpha also enhanced the expression of Bcl-2 family proteins in an NF-kappaB-dependent manner. CONCLUSIONS: TGF-alpha plays an antiapoptotic role in gastric mucosal cells via the NF-kappaB-dependent pathway.

Animals↗
PubMed2001

Characteristic association between K-ras gene mutation with loss of heterozygosity in X-ray-induced thymic lymphomas of the B6C3F1 mouse.

PURPOSE: To elucidate the characteristics of radiation carcinogenesis, the spectra of K- and N-ras oncogene mutations, loss of heterozygosity (LOH) and their association in X-ray-induced thymic lymphomas (TL) were determined by comparing with those of N-ethyl-N-nitrosourea (ENU)-induced and spontaneously occurring TL. MATERIALS AND METHODS: TL that arose in untreated, X-ray-irradiated and ENU-treated B6C3F1 mice were examined both for K- and N-ras mutations by PCR-SSCP and DNA sequencing and for LOH by PCR with polymorphic microsatellite markers. RESULTS: (1) ras gene mutations were found in a proportion of TL from X-ray-exposed (approximately 20%) and ENU-treated (30-40%) mice while no ras gene mutations were found in spontaneous TL. N-ras mutations were rare. (2) The spectrum of ras gene mutations was diverse and seemed to differ little between X-ray-induced and ENU-induced TL, even though there was a higher frequency of ras mutations in ENU-induced TL that clustered to K-ras codon 12. (3) The X-ray-induced TL showing K-ras mutation were associated with LOH on chromosome 6, while those showing no K-ras mutation were associated with high frequency of LOH on chromosomes 4, 11 and 12. CONCLUSION: These results demonstrate that, in the B6C3F1 mouse TL, X-ray-induced lymphomagenesis showed both the co-expression, yet low occurrence of allelic imbalance on chromosome 6 and K-ras mutation, and exclusive expression of frequent allelic imbalance on chromosomes 4, 11 and 12 and K-ras mutation.

Animals↗
PubMed2001

Preliminary findings in germinal vesicle transplantation of immature human oocytes.

Transplanting a germinal vesicle (GV) from an aged woman's oocyte into a younger ooplasm has been proposed as a possible way to reduce the incidence of oocyte aneuploidy which is considered to be responsible for age-related infertility. In this study, we have assessed the efficiency of each step involved in nuclear transplantation-specifically cell survival, nuclear-cytoplasmic reconstitution, and the capacity of the reconstituted oocytes for in-vitro maturation. In addition, we have evaluated the fertilizability and karyotypic status of the manipulated oocytes by intracytoplasmic sperm injection (ICSI) and fluorescent in-situ hybridization technique respectively. Nuclear transplantation was accomplished with an overall efficiency of 73%. Due to the limited availability of materials, most nuclear transplantation procedures were performed between sibling oocytes. The maturation rate of 62% following reconstitution was comparable with that of control oocytes, as was the incidence of aneuploidy among the reconstituted oocytes. The ICSI results of the reconstituted oocytes yielded a survival rate of 77%, a fertilization rate of 52%, and a satisfactory early embryonic cleavage. Furthermore, in a limited number of observations where the nucleus of an aged oocyte was transferred into a younger ooplasm, there was an appropriate chromosomal segregation. These findings demonstrate that human oocytes reconstituted with GV nuclei are able to undergo maturation, fertilization, and early embryo cleavage, and maintain a normal ploidy. Although in-vitro maturation seems to be a limiting step, this technique would allow us to investigate further the nuclear-ooplasmic relationship during meiotic maturation.

Adult↗
PubMed2001

Association of CTLA-4 but not CD28 gene polymorphisms with systemic lupus erythematosus in the Japanese population.

OBJECTIVE: Systemic lupus erythematosus (SLE) in a multisystem autoimmune disorder characterized by multiorgan pathology and autoantibodies against a variety of autoantigens. The CD28 and CTLA-4 genes might be candidate genes for SLE, because costimulation signals from CD80/CD86 to CD28/CTLA-4 have been suggested to play an important role in the activation or inactivation of T lymphocytes. METHODS: We investigated three polymorphic regions within the CTLA-4 gene, a C/T base exchange in the promoter region -318 (CTLA-4 -318C/T), an A/G substitution in the exon 1 position 49 (CTLA-4 49A/G), an (AT)(n) repeat polymorphism in the 3' untranslated region of exon 4 [CTLA-4 3' (AT)(n)], and a CD28 gene polymorphism, a T/C substitution in the intron 3 position +17 (CD28 IVS3+17T/C), in SLE patients and controls. RESULTS: SLE patients had significantly higher frequencies of the CTLA-4 49G allele (P=0.003) and of the CTLA-4 (AT)(n) 106 bp allele (P=0.0008) than controls. We also found a strong linkage disequilibrium between the A allele of CTLA-4 49A/G and the 86 bp allele of CTLA-4 3' (AT)(n). On the contrary, no association was found between SLE and CTLA-4 -318C/T or CD28 IVS3 +17T/C. CONCLUSION: We conclude that the CTLA-4 gene appears to play a significant role in the development of SLE in the Japanese population.

Abatacept↗
PubMed2001

Robustness to head misalignment of virtual sound imaging systems.

When binaural sound signals are presented with two loudspeakers, the listener's ears are required to be in the relatively small region which is under control of the system. Misalignment of the head results in inaccurate synthesis of the binaural signals. Consequently, directional information associated with the acoustic signals is inaccurately reproduced. When the two loudspeakers are placed close together, the spatial rate of change of the generated sound field is much smaller than that generated by two loudspeakers spaced apart. Therefore, the performance of such a system is expected to be more robust to misalignment of the listener's head. Robustness of performance is investigated here with respect to head displacement in three translational and three rotational directions. A comparison is given between systems consisting of two loudspeakers either placed close together or spaced apart. The extent of effective control with head displacement and the resulting deterioration in directional information is investigated in the temporal and spectral domain by analyzing synthesized binaural signals. Subjective localization experiments are performed for cases in which notable differences in performance are expected from the previous analysis. It is shown that the system comprising two loudspeakers that are close together is very robust to misalignment of the listener's head.

Acoustics↗
PubMed2001

Expression of Gab1 lacking the pleckstrin homology domain is associated with neoplastic progression.

An in vitro transformation system of carcinogen-treated Syrian hamster embryo (SHE) cell cultures represents multistep genetic and nongenetic changes that develop during the neoplastic progression of normal cells to tumor cells in vivo. During this neoplastic progression, SHE cells demonstrate an altered response to epidermal growth factor (EGF). In the present report, we examined the role of the adapter protein Gab1 (Grb2-associated binder-1) in the neoplastic progression of SHE cells. We used two asbestos-transformed SHE cell clones in different neoplastic stages: a 10W+8 clone, which is immortal and retains the ability to suppress the tumorigenicity of tumor cells in cell-cell hybrid experiments, and a 10W-1 clone, which has lost this tumor suppressor ability. 10W+8 cells expressed full-length 100-kDa Gab1 and associated 5.2-kb mRNA. Upon repeated cell passaging, 10W-1 cells showed increasing expression of a novel 87-kDa form of Gab1 as well as 4.6-kb mRNA with diminishing expression of the original 100-kDa Gab1. cDNA encoding the 87-kDa Gab1 predicts a form of Gab1 lacking the amino-terminal 103 amino acids (Gab1(Delta1-103)), which corresponds to loss of most of the pleckstrin homology (PH) domain. Gab1(Delta1-103) retains the ability to be phosphorylated in an EGF-dependent manner and to associate with the EGF receptor and SHP-2 upon EGF stimulation. The endogenous expression of Gab1(Delta1-103) in 10W-1 cells appeared closely related to EGF-dependent colony formation in soft agar. Moreover, transfection and expression of Gab1(Delta1-103), but not Gab1, in 10W+8 cells enhanced their EGF-dependent colony formation in soft agar. These results demonstrate that Gab1 is a target of carcinogen-induced transformation of SHE cells and that the expression of a Gab1 variant lacking most of the PH domain plays a specific role in the neoplastic progression of SHE cells.

Agar↗
PubMed2001

Hepatocellular carcinoma: involvement of the internal mammary artery.

PURPOSE: To investigate factors related to the development of internal mammary arteries (IMAs) as feeding arteries of hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: In 30 patients with HCC located in ventral hepatic areas directly beneath the diaphragm, bilateral internal mammary arteriography was performed to explore involvement of the IMA with HCC. The number of previous transcatheter arterial embolizations (TAEs), tumor size, time from initial TAE to IMA angiography, inferior phrenic artery (IPA) involvement with tumor, presence of hepatic artery occlusion, and use of other treatments were compared in groups with and without involvement of the IMA. RESULTS: The group with IMA involvement included 10 patients; the group without involvement, 20 patients. TAE had been performed two to 12 times in the group with involvement and zero to six times in the group without involvement (P =.01). Mean tumor sizes in these two groups were 5.1 and 6.0 cm, respectively; hepatic artery occlusion was noted in nine and zero patients (P =.01) in the two groups. The time from initial TAE to IMA angiography ranged from 3 to 53 months (median, 31.5 months) and from zero to 89 months (median, 0 months) (P =.01). IPA involvement was observed in seven and four patients (P =.015). CONCLUSION: These results strongly suggest that, regardless of tumor size, when HCCs are located in the ventral hepatic areas directly beneath the diaphragm, the IMAs serve as feeding arteries in patients with hepatic artery occlusion caused by repeated TAE.

Aged↗
PubMed2001

Expression of Ca(2+)-activated K(+) channels, SK3, in the interstitial cells of Cajal in the gastrointestinal tract.

A role for small-conductance Ca(2+)-activated K(+) (SK) channels on spontaneous motility of the gastrointestinal tract has been suggested. Although four subtypes of SK channels were identified in mammalian tissues, the subtypes of SK channel expressed in the gastrointestinal tract are still unknown. In this study, we investigated the expression and localization of SK channels in the gastrointestinal tract. RT-PCR analysis shows expression of SK3 and SK4 mRNA, but not SK1 or SK2 mRNA, in the rat intestine. SK3 immunoreactivity was detected in the myenteric plexus and muscular layers of the stomach, ileum, and colon. SK3-immunoreactive cells were stained with antibody for c-kit, a marker for the interstitial cells of Cajal (ICC), but not with that for glial fibrillary acidic protein in the ileum and stomach. Immunoelectron microscopic analysis indicates that SK3 channels are localized on processes of ICC that are located close to the myenteric plexus between the longitudinal and circular muscle layers and within the muscular layers. Because ICC have been identified as pacemaker cells and are known to play a major role in generating the regular motility of the gastrointestinal tract, these results suggest that SK3 channels, which are expressed specifically in ICC, play an important role in generating a rhythmic pacemaker current in the gastrointestinal tract.

Animals↗
PubMed2001

Regulation of platelet aggregation in vitro by plasma adenosine in preeclampsia.

The aim of this study was to evaluate the possible role of plasma adenosine in platelet aggregation in preeclampsia. We measured the plasma adenosine concentration [ADO] and in vitro platelet aggregation in the third trimester of normal pregnant (n = 15) and preeclamptic women (n = 15). The mean plasma [ADO] in preeclampsia was 0.68 +/- 0.08 microM (means +/- SEM), significantly higher than in normal pregnancy (0.42 +/- 0.09 microM) (p < 0.05). In preeclampsia, platelet aggregation in response to collagen was approximately 40% lower than that in normal pregnancy (p < 0.05). There was an inverse correlation between the plasma [ADO] and platelet aggregation in vitro (r = -0.27, p < 0.05). These results suggest reduced platelet aggregation in preeclampsia may be at least in part attributed to an elevation of the the plasma [ADO].

Adenosine↗
PubMed2001

Relation between serum uric acid and plasma adenosine levels in women with preeclampsia.

The aim of this study was to examine the relationship between plasma adenosine and serum uric acid levels in women with preeclampsia. Maternal arterial blood sampling was performed to measure serum uric acid and plasma adenosine levels in 20 pregnant women complicated by preeclampsia and 22 normal pregnant women at 33-38 weeks of gestation. The average plasma adenosine levels were 0.31 +/- 0.12 micromol/l in the normal pregnant group and 0.45 +/- 0.11 micromol/l in the preeclampsia group. The mean serum uric acid level in women with preeclampsia was 5.9 +/- 0.60 mg/dl, significantly higher than in the normal pregnant women (4.4 +/- 0.69 mg/dl). Positive correlations were found between serum uric acid and plasma adenosine levels in both the group with (r(2) = 0.38, p < 0.05) and the group without (r(2) = 0.54, p < 0.05) preeclampsia. There was also a significant correlation between serum uric acid and plasma adenosine levels on the whole (r(2) = 0.59, p < 0.05). Our results suggest that increased adenosine is a contributing source of preeclamptic hyperuricemia.

Adenosine↗
PubMed2001

Upregulatory expression of furin and transforming growth factor-beta by fluid shear stress in vascular endothelial cells.

Furin, a yeast Kex2-family endoprotease, converts many vasoregulatory propeptides, including pro-transforming growth factor (TGF)-beta to their mature forms. We examined whether furin expression is regulated by shear stress in vivo and in vitro. When an arteriovenous shunt was placed between the carotid artery and external jugular vein in rabbits, furin and TGF-beta were highly expressed in shear stress-loaded endothelial cells. Exposure of bovine aortic endothelial cells in culture to shear stress induced furin and TGF-beta expression in a similar manner. Molecular analysis of furin expression in bovine aortic endothelial cells revealed that shear stress increases the furin gene expression at transcriptional levels. Furthermore, TGF-beta itself increased the furin mRNA levels. Shear-mediated furin expression was partly mediated by TGF-beta because shear-induced furin mRNA levels were considerably decreased by overexpression of the truncated form of the TGF-beta type II receptor. Likewise, blockade of furin activity by a furin inhibitor significantly decreased the endothelial production of mature TGF-beta. Taken together, the results indicate that furin expression is induced and maintained by a coordination of shear stress and TGF-beta. Increased furin expression may facilitate the formation of mature TGF-beta, resulting in the enhanced effects of TGF-beta on endothelial cells and vascular smooth muscle cells in the vasculature.

Animals↗
PubMed2001

Usefulness of saturation pulses in magnetic resonance imaging of partial anomalous pulmonary venous return.

The authors evaluated partial anomalous pulmonary venous return by magnetic resonance (MR) images. Seven patients with this congenital anomaly underwent MR imaging examination. Conventional spin-echo and gradient-echo imaging were performed. In addition, during acquisition of gradient-echo images, saturation pulses were imposed on the affected lung. Spin-echo images showed the anatomical situation of the anomalous veins, and gradient-echo images revealed the blood flow in the veins. With saturation technique, the direction and drainage of blood flow in the anomalous veins were well defined. The study suggests that MR imaging with spin-echo method and gradient-echo method with or without saturation pulses is a useful and noninvasive method of diagnosing partial anomalous pulmonary venous return. MR images with spin- and gradient-echo methods were useful in defining the anatomical situation and blood flow in the anomalous veins. By imposing saturation pulses on the affected lung field, the direction and drainage of blood flow in the anomalous veins were clearly demonstrated.

Adolescent↗
PubMed2001

Male reproductive defects caused by puromycin-sensitive aminopeptidase deficiency in mice.

Male reproductive performance is composed of two principal elements, copulation and spermatogenesis. A wealth of literature has described the intricate web of endocrine events underlying these biological processes. In the present study we show that puromycin-sensitive aminopeptidase (Psa)-deficient mice are infertile, lack copulatory behavior, and have impaired spermatogenesis. The reproductive deficits of the mutants are not restored by androgen administration, although no aberrant localization of the sex steroid receptors was detectable in their brains and testes. Considering the strong expression of the Psa gene in the brain and Sertoli cells and the degenerative morphology of Sertoli cells in Psa-deficient mice, Psa may participate in testosterone-mediated reproductive signal pathways in the brain and testis.

Aminopeptidases↗
PubMed2001

Puromycin-sensitive aminopeptidase is essential for the maternal recognition of pregnancy in mice.

Maternal recognition of pregnancy in rodents requires semicircadian surges of hypophyseal PRL secretion during early gestation, which are required for the formation of the corpus luteum of pregnancy (CLP). Here we show that puromycin-sensitive aminopeptidase (Psa)-deficient mice display female infertility that results from impaired formation of CLP. Transplantation of mutant ovaries into normal females restored fertility but not vice versa. Psa-deficient females revealed no semicircadian surges of PRL induced after mating stimuli. Pregnancy in the mutant females was restored by grafting intact pituitaries to elevate circulating levels of PRL. Psa is thus required for the appearance of the semicircadian surges of PRL secretion that are crucial for maintaining pregnancy in rodents.

Aminopeptidases↗
PubMed2001

Effect of 1DMe, a neuropeptide FF analog, on acetylcholine release from myenteric plexus of guinea pig ileum.

Since neuropeptide FF (NPFF) is a putative neurotransmitter to exert anti-opioid activity, we examined the effects of [D-Tyr', (NMe)Phe3]neuropeptide FF (IDMe), a stable NPFF analog, on acetylcholine (ACh) release from a longitudinal muscle-myenteric plexus (LMMP) preparation of guinea pig ileum in which opioids were known to inhibit ACh release when muscarinic autoinhibition was not fully activated. In the presence of atropine, 1DMe increased spontaneous and electrical field stimulation (EFS)-evoked ACh release in a concentration-dependent manner. Naloxone also increased ACh release. The stimulatory effects of 1DMe and naloxone were not additive. In the absence of atropine, 1DMe did not affect ACh release. Morphine decreased spontaneous and EFS-evoked ACh release in the presence of 1 microM atropine. 1DMe as well as naloxone counteracted the inhibitory effects of morphine on EFS-evoked ACh release. The combination of 1DMe and naloxone was not more inhibitory than either drug alone. 1DMe had no appreciable effect on norepinephrine-induced inhibition of spontaneous and EFS-evoked ACh release. These results first demonstrated the effects of a NPFF analog on neurotransmitter release: 1DMe had a stimulatory effect on spontaneous and EFS-induced ACh release from the LMMP preparation of guinea pig ileum, probably by counteracting the inhibitory effect of endogenous opioids on ACh release.

Acetylcholine↗