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Biomedical subjects

Y Takeuchi

Publications and source records attributed to Y Takeuchi.

At least 109 records · Page 6Linked to original sources
PubMed2000

Cloning and characterization of two promoters for the human calcium-sensing receptor (CaSR) and changes of CaSR expression in parathyroid adenomas.

Histological analyses showed that expression of the parathyroid calcium-sensing receptor (CaSR) is decreased in parathyroid adenomas. Because reduced expression of CaSR may result in insufficient suppression of parathyroid hormone secretion, the elucidation of regulatory mechanisms of CaSR expression is indispensable for understanding the pathogenesis of parathyroid adenomas. Two cDNA clones for human CaSR with different 5'-untranslated regions have been isolated. However, the structure of the promoter region of human CaSR and the mechanisms of production of multiple CaSR mRNAs are unknown. We have cloned promoter regions of human CaSR by screening a genomic library. The human CaSR gene has two promoters and two 5'-untranslated exons (exons 1A and 1B), and alternative usage of these exons leads to production of multiple CaSR mRNAs. The upstream promoter has TATA and CAAT boxes, and the downstream promoter is GC-rich. Northern blot analysis showed that expression levels of exon 1A in parathyroid adenomas are significantly less than those in normal glands. However, expression of exon 1B was not different between adenomas and normal glands. Thus, specific reduction of the transcript driven by the upstream promoter was observed in parathyroid adenomas. Further analyses of factors that modulate the activity of the upstream promoter are necessary to clarify the pathogenesis of parathyroid adenomas.

Adenoma↗
PubMed2000

A novel and efficient synthesis of 3-fluorooxindoles from indoles mediated by Selectfluor.

[reaction: see text] Treatment of several 3-substituted indoles, including derivatives of tryptophan and serotonin, with commercially available Selectfluor in acetonitrile/water furnished 3-substituted 3-fluorooxindoles in good to high yields. Since 3-fluorooxindoles obtained are sterically similar to both oxindoles and 3-hydroxyoxindoles, they should be useful as probes for investigating the enzymatic mechanism of indole biosynthesis and metabolism.

Diazonium Compounds↗
PubMed2000

Anti-ischemic effect of a novel cardioprotective agent, JTV519, is mediated through specific activation of delta-isoform of protein kinase C in rat ventricular myocardium.

BACKGROUND: A new 1,4-benzothiazepine derivative, JTV519, has a strong protective effect against Ca(2+) overload-induced myocardial injury. We investigated the effect of JTV519 on ischemia/reperfusion injury in isolated rat hearts. METHODS AND RESULTS: At 30 minutes of reperfusion after 30-minute global ischemia, the percent recovery of left ventricular developed pressure was improved, and the creatine phosphokinase and lactate dehydrogenase leakage was reduced in a concentration-dependent manner when JTV519 was administered in the coronary perfusate both at 5 minutes before the induction of ischemia and at the time of reperfusion. The myocardial protective effect of JTV519 was completely blocked by pretreatment of the heart with GF109203X, a specific protein kinase C (PKC) inhibitor. In contrast, the effect of JTV519 was not affected by alpha(1)-, A(1)-, and B(2)-receptor blockers that couple with PKC in the cardiomyocyte. Both immunofluorescence images and immunoblots of JTV519-treated left ventricular myocardium and isolated ventricular myocytes demonstrated that this agent induced concentration-dependent translocation of the delta-isoform but not the other isoforms of PKC to the plasma membrane. CONCLUSIONS: The mechanism of cardioprotection by JTV519 against ischemia/reperfusion injury involves isozyme-specific PKC activation through a receptor-independent mechanism. This agent may provide a novel pharmacological approach for the treatment of patients with acute coronary diseases via a subcellular mechanism mimicking ischemic preconditioning.

Animals↗
PubMed2000

Interactions between cancer and bone marrow cells induce osteoclast differentiation factor expression and osteoclast-like cell formation in vitro.

Cancer cells metastasized to bone induce osteoclastogenesis for bone destruction. Coculture of either mouse melanoma B16 or breast cancer Balb/c-MC cells with mouse bone marrow cells (BMCs) induced osteoclast-like cells, which were not observed when cancer cells were segregated from BMCs. Osteoclast differentiation factor (ODF), also known as receptor activator of NF-kappaB ligand (RANKL), is a direct mediator of many osteotropic factors. Neither BMCs, B16 nor Balb/c-MC cells alone expressed ODF mRNA. However, coculture of these cancer cells with BMCs induced ODF expression, which was prevented by indomethacin. Moreover, the coculture with cancer cells inhibited secretion of osteoprotegerin/osteoclastogenesis inhibitory factor (OPG/OCIF), an inhibitory decoy receptor for ODF, from BMCs. Thus, enhanced osteoclastogenesis in the presence of cancer cells might be due to an increase in ODF activity. These results suggest that interactions between cancer cells and BMCs induce ODF expression and suppress OPG/OCIF level in metastatic foci resulting in pathological osteoclastogenesis for bone destruction.

Animals↗
PubMed2000

New efficient chiral derivatizing agent, alpha-cyano-alpha-fluoro(2-naphthyl)acetic acid (2-CFNA). application to the EE determination of (-)-3-acetoxy-2-fluoro-2-(hexadecyloxymethyl)propan-1-ol.

The new chiral derivatizing agent (CDA), alpha-cyano-alpha-fluoro(2-naphthyl)-acetic acid (2-CFNA) 1 was prepared in optically pure form by chiral HPLC separation of racemic 2-CFNA methyl ester (2-CFNA Me ester) (+/-)-2. The ester was obtained by fluorination of methyl alpha-cyano(2-naphthyl)acetate with FClO3. 2-CFNA 1 has proven to be a significantly superior CDA for determination of enantiomeric excess (ee) of a primary alcohol when compared to alpha-methoxy-alpha-trifluoromethylphenylacetic acid (MTPA, Mosher's agent) and alpha-cyano-alpha-fluoro(p-tolyl)acetic acid (CFTA). The ee of (-)-3-acetoxy-2-fluoro-2-(hexadecyloxymethyl)propan-1-ol (-)-9, a fluorinated analog of anticancer active ether lipids, was determined using (+)-2-CFNA (+)-1.

Journal Article↗
PubMed2000

Two-dimensional analysis of phospholipids by capillary liquid chromatography/electrospray ionization mass spectrometry.

A phospholipid mixture extracted from cultured cells was directly analyzed by capillary (Cap) liquid chromatography (LC)/electrospray ionization (ESI) mass spectrometry (MS). Using a quadrupole mass spectrometer, we analyzed positive molecular ions, negative molecular ions, positive fragment ions and negative fragment ions under four different functions. In the analysis of the elution patterns of the phospholipids, a two-dimensional map, in which the first dimension is elution time and the second dimension is mass, proved useful. Consequently, four different maps can be obtained by each of four different functions. Among them, from negative fragment ions at high cone voltage in the negative ion mode, ions that originated from acyl fatty acid and phosphorylcholine, phosphorylethanolamine and cyclic inositol phosphate can be detected at specific elution times. The map from positive fragment ions at high cone voltage in the positive ion mode indicated ions such as diradylglycerol and derivatives of 1-alkyl or 1-alkenyl cyclic phosphatidic acid from phosphatidylethanolamine (PE), and phosphorylcholine from choline-containing phospholipids. The map produced from positive molecular ions indicated choline-containing phospholipids such as phosphatidylcholine, sphingomyelin, lysophosphatidylcholine and PE. The map of negative molecular ions effectively indicated acidic phospholipids such as phosphatidylinositol. We were able to obtain more than 500 molecular species of phospholipids by this method within a few hours immediately after extraction from culture cells using a mixture of chloroform and methanol (2:1). In this context, we concluded that the combination of Cap-LC and ESIMS seems to be very effective in the analysis of phospholipid classes and their molecular species.

Animals↗
PubMed2000

Neurons in the hilus region of the rat hippocampus are depleted in number by exposure to alcohol during early postnatal life.

We have previously shown that exposing rats to a relatively high dose of ethanol during early postnatal life resulted in a deficit in spatial learning ability. This ability is controlled, at least in part, by the hippocampal formation. The purpose of the present study was to determine whether exposure of rats to ethanol during early postnatal life affected the number of specific neurons in the hippocampus. Wistar rats were exposed to a relatively high daily dose of ethanol between postnatal days 10 and 15 by placing them for 3 h each day in a chamber containing ethanol vapor. The blood ethanol concentration was about 430 mg/dl at the end of the exposure period. Groups of ethanol-treated (ET) rats, separation controls (SC), and mother-reared controls (MRC) were anesthetized and killed at 16 days of age by perfusion with phosphate-buffered glutaraldehyde (2.5%). The Cavalieri principle was used to determine the volume of various subdivisions of the hippocampal formation (CA1, CA2+CA3, hilus, and granule cell layer), and the physical disector method was used to estimate the numerical densities of neurons within each subdivision. The total number of neurons was calculated by multiplying estimates of the numerical density with the volume. There were, on average, about 441,000 granule cells in the granule cell layer and 153,000 to 177,000 pyramidal cells in both the CA1 and CA2+CA3 regions in all three treatment groups. In the hilus region, ET rats had about 27,000 neuronal cells. This was significantly fewer than the average of 38,000 such neurons estimated to be present in both MRC and SC animals. Thus, neurons in the hilus region may be particularly vulnerable to the effects of a high dose of ethanol exposure during early postnatal life.

Animals↗
PubMed2000

Antibody-regulated neurotoxic function of cell-surface beta-amyloid precursor protein.

APP is a transmembrane precursor of beta-amyloid, and its mutations cause early-onset familial Alzheimer's disease. We report a toxic function of normal wild-type APP (wtAPP). Treatment of neuronal F11 cells, immortalized embryonic day 13 neurons, overexpressing wtAPP with anti-APP antibodies caused death. Death was not induced by antibody in parental F11 cells. Death by antibody occurred through cell-surface APP, not through secreted APP, in a pertussis toxin-sensitive manner and was typical apoptosis, not observed in primary astrocytes or glioma cells overexpressing wtAPP, but observed in primary cortical neurons. Cell-surface APP thus performs a toxic function as an extracellularly controllable regulator of neuronal death. This study provides a novel insight into the normal and pathological functions of cell-surface wtAPP.

Alzheimer Disease↗
PubMed2000

Continuous estimation of systolic blood pressure using the pulse arrival time and intermittent calibration.

A continuous noninvasive method of systolic blood pressure estimation is described. Systolic blood pressure is estimated by combining two separately obtained components: a higher frequency component obtained by extracting a specific frequency band of pulse arrival time and a lower frequency component obtained from the intermittently acquired systolic blood pressure measurements with an auscultatory or oscillometric system. The pulse arrival time was determined by the time interval from QRS apex in electrocardiogram to the onset of photoplethysmogram in a fingertip beat-by-beat via an oximetric sensor. The method was examined in 20 patients during cardiovascular surgery. The estimated values of systolic blood pressure were compared with those measured invasively using a radial arterial catheter. The results showed that the correlation coefficients between estimated values and invasively obtained systolic blood pressure reached 0.97 +/- 0.02 (mean +/- SD), and the error remained within +/- 10% in 97.8% of the monitoring period. By using a system with automatic cuff inflation and deflation to acquire intermittent systolic blood pressure values, this method can be applicable for the continuous noninvasive monitoring of systolic blood pressure.

Adolescent↗
PubMed2000

Tricuspid valve replacement after cardiac transplantation.

Tricuspid regurgitation, a fairly common finding after cardiac transplantation, is generally mild or moderate, and is not clinically significant. The etiology of tricuspid regurgitation is not entirely understood, and experience with valve replacement after cardiac transplantation is limited. We describe a case of progressively severe tricuspid regurgitation ultimately requiring tricuspid valve replacement. At operation, the ruptured chordae of the posterior part of anterior and septal leaflet with resulting partially flail leaflets were found. Examination of the papillary muscle showed origins of several of the ruptured chordae. Damage to the tricuspid subvalvular apparatus at endomyocardial biopsy appeared to be a possible cause. A 31-mm Carpentier-Edwards porcine valve was implanted. This was because replacement with a mechanical prosthesis would prevent future right-side heart catheterization and endomyocardial biopsy and in valve repair, the patient remains exposed to the risk of the recurrence of chordal rupture. We discuss proposed causes and choices in surgical technique.

Adult↗
PubMed2000

Technical aspects of venous stenting in high-grade stenoses using a long guidewire between dual venous access sites.

We describe the technical benefits of the dual-access technique for venous stenting in high-grade stenosis. Stents were implanted successfully with this technique in all patients, although the preceding transfemoral interventions had failed. The dual-access technique is useful to facilitate the intervention when the stenoses are too severe to place the stent through just a single access point.

Aged↗
PubMed2000

Aberrant chloroplasts in transgenic rice plants expressing a high level of maize NADP-dependent malic enzyme.

NADP-dependent malic enzyme (NADP-ME) is a major decarboxylating enzyme in NADP-ME-type C4 species such as maize and Flaveria. In this study, chloroplastic NADP-ME was transferred to rice (Oryza sativa L.) using a chimeric gene composed of maize NADP-ME cDNA under the control of rice light-harvesting chlorophyll-a/b-binding protein (Cab) promoter. There was a 20- to 70-fold increase in the NADP-ME activity in leaves of transgenic rice compared to that in wild-type rice plants. Immunocytochemical studies by electron microscopy showed that maize NADP-ME was mostly localized in chloroplasts in transgenic rice plants, and that the chloroplasts were agranal without thylakoid stacking. Chlorophyll content and photosystem II activity were inversely correlated with the level of NADP-ME activity. These results suggest that aberrant chloroplasts in transgenic plants may be caused by excessive NADP-ME activity. Based on these results and the known fact that only bundle sheath cells of NADP-ME species, among all three C4 subgroups, have agranal chloroplasts, we postulate that a high level of chloroplastic NADP-ME activity could strongly affect the development of chloroplasts.

Chlorophyll↗
PubMed2000

Characterization of pectin methyltransferase from soybean hypocotyls.

Pectin methyltransferase (PMT) catalyzing the transfer of the methyl group from S-adenosyl-L-methionine (SAM) to the C-6 carboxyl group of galactosyluronic acid residues in pectin was found in a membrane preparation of etiolated hypocotyls from 6-d-old soybean (Glycine max Merr.). The enzyme was maximally active at pH 6.8 and 35-40 degrees C, and required 0.5% (w/v) Triton X-100. The incorporation of the methyl group was significantly enhanced by addition of a pectin with a low (22%) degree of methyl-esterification (DE) as exogenous acceptor substrate. The apparent Michaelis constants for SAM and the pectin (DE22) were 0.23 mM and 66 microg x ml(-1), respectively. Attachment of the methyl group to the carboxyl group of the pectin via ester linkage was confirmed by analyzing radiolabeled product from incubation of the enzyme with [14C]methyl SAM and the acceptor pectin. Size-exclusion chromatography showed that both enzymatic hydrolysis with a pectin methylesterase and a mild alkali treatment (saponification) led to the release of radioactive methanol from the product. Enzymatic hydrolysis of the product with an endopolygalacturonase degraded it into small pectic fragments with low relative molecular mass, which also supports the idea that the methyl group is incorporated into the pectin. The soybean hypocotyls were fractionated into their cell wall components by successive extraction with water, EDTA, and alkali treatment. Among the resulting polysaccharide fractions, high PMT activity was observed when a de-esterified polysaccharide derived from the EDTA-soluble fraction (the pectic fraction) was added as an alternative acceptor substrate, indicating that the enzyme may be responsible for producing methyl-esterified pectin in vivo.

Cell Wall↗
PubMed2000

Evaluation of autonomic nervous function during upper gastrointestinal endoscopy using heart rate variability.

To investigate autonomic nervous function during upper gastrointestinal endoscopy, we analyzed R-R interval variability from electrocardiograms obtained during endoscopy. Holter electrocardiogram recordings were made before and after premedication, and during endoscopy. Time- and frequency-domain analyses of heart rate variability were performed in 54 subjects premedicated with scopolamine butylbromide (SB group) and in 66 subjects premedicated with glucagon (G group). To determine the effect of autonomic imbalance on arrhythmia generation during endoscopy, subjects with arrhythmias (A group) were compared with subjects without arrhythmias (N group). In the SB group, high frequency spectral power (HF power; 0.15 to 0.40 Hz), which reflects parasympathetic activity, decreased significantly after premedication, and decreased further during endoscopy (P < 0.01). Moreover, HF power before premedication or during endoscopy in the A group was significantly lower than that in the N group (P < 0.01). This study suggests that the measurement of HF power prior to endoscopy can identify subjects with reduced HF power. This should allow the prevention of cardiovascular complications related to premedication and endoscope insertion.

Adult↗
PubMed2000

Extensive lymphopenia due to apoptosis of uninfected lymphocytes in acute measles patients.

Infection with measles virus induces a transient immunosuppression, which occasionally results in fatal opportunistic infections. To obtain fundamental information about the mechanism, we examined peripheral blood mononuclear cells (PBMC) from acute measles patients aged from infants to 35 years old, obtained at various times from incubation periods to 103 days after onset of rash, for the number of lymphocyte subsets by flowcytometry. The data were analyzed for relationships between aging of the patients and the severity of immunosuppression. In classical measles cases, infected lymphocytes detected as a minor population during the incubation period disappeared soon after onset of rash, whereas in the cases of serious illness, the infected cells persisted longer after the rash. At the onset of rash, remarkable lymphopenia had already occurred in all measles cases with reduction in cell numbers of CD4+ T cells, CD8+ T cells, B cells, neutrophils, and monocytes. In contrast, natural killer (NK) cells were increased in number and activated, which might be a response compensatory for the lymphopenia. Apoptosis-associated molecules such as CD95(Fas) and TNF-related apoptosis-inducing ligand-receptor (TRAIL-R) were highly expressed on the cell surface of most surviving non-infected lymphocytes, and DNA fragmentation was also observed upon incubation in vitro. These results suggested that the profound lymphopenia was primarily due to extended death of non-infected blood cells caused by apoptosis. The severity and duration of the lumphopenia were age-dependent; less severe in young children whereas much severer in infants under one year of age as well as adolescents and adults. From these results, it was suggested that remarkable lymphopenia due to apoptosis of uninfected cells is one of the principal causes for immunosuppression induced by measles virus infection, and is correlated with the age-dependent severity of the disease.

Acute Disease↗
PubMed2000

Twenty-two-year follow-up of saphenous vein grafts in pediatric Kawasaki disease.

We describe 2 Kawasaki disease patients with excellent long-term patency of saphenous vein grafts, who underwent coronary artery bypass at age 7 and 9 years, respectively, and demonstrated normal growth during 22 years of follow-up. The grafts showed no deterioration and played an important role in coronary blood supply.

Child↗
PubMed2000

Lower sternal splitting approach for off-pump coronary artery bypass grafting.

There are several ways to revascularize coronary arteries without cardiopulmonary bypass using a minimally invasive method. Currently, one of the most commonly used methods is minimally invasive direct coronary artery bypass (MIDCAB) through a left thoracotomy. Using this technique, however, only the left anterior descending and diagonal branch can be grafted. This article describes coronary revascularization of the left anterior descending artery or right coronary artery, or both, via a lower ministernotomy without a transverse cut, namely, the lower sternal splitting method. Through this approach, the left anterior descending, diagonal, and right coronary arteries can be revascularized using a single, minimally invasive approach without the risk of damaging the tissue around the intercostal space when the sternum is transversely divided.

Aged↗