Biomedical subjects

K Takeuchi

Publications and source records attributed to K Takeuchi.

At least 91 records · Page 5Linked to original sources

PubMed1992

Brain natriuretic peptide as a cardiac hormone in essential hypertension.

PURPOSE: A natriuretic peptide, brain natriuretic peptide (BNP), has been isolated from porcine hearts. We performed this study to determine if BNP is secreted from the heart and to identify changes, if any, in the plasma BNP concentration in essential hypertension. PATIENTS AND METHODS: We measured the immunoreactive (ir) BNP concentration at intracardiac sites including the coronary sinus of five patients with heart disease during cardiac catheterization. We examined plasma ir-BNP in 48 hypertensive patients, 15 borderline hypertensive patients, and 25 normotensive subjects. RESULTS: Plasma ir-BNP in the coronary sinus was greater than at other cardiac sites. The concentration was significantly higher in hypertensive subjects than in borderline hypertensive or normotensive subjects. Hypertensive patients with left ventricular hypertrophy (LVH) established by echocardiography had higher plasma ir-BNP levels than those without LVH. In the hypertensive group, plasma ir-BNP was closely correlated with the LV mass index. In these patients, BNP levels were correlated with mean arterial pressure and inversely correlated with the LV ejection fraction, although these correlations were weak. Reverse-phase high-pressure liquid chromatography showed that the major component of circulating ir-BNP in the hypertensive and normotensive subjects corresponded to authentic human BNP-32. CONCLUSIONS: Human BNP-32 was secreted through the coronary sinus from the heart and may act as a cardiac hormone. Plasma BNP was increased in many of the hypertensive subjects with LVH. The increase in BNP seemed to be related to LVH or the cardiac overload associated with LVH.

Adult↗

PubMed1992

A prostacyclin analogue reduces free radical generation in heart-lung transplantation.

The mechanism by which prostacyclin acts to prevent in vivo reperfusion injury is still uncertain. This study was therefore undertaken to assess the effect of a stable prostacyclin analogue (OP 41483-alpha-CD [OP]) on oxygen-derived free radicals after heart-lung transplantation. OP was administered to the heart-lung graft through the pulmonary artery for 25 minutes encompassing the reperfusion process. Free radicals were directly measured by electron spin resonance spectroscopy. The radical intensities of pulmonary venous blood were significantly lower in the OP group than in the control group, suggesting that fewer free radicals were generated in the lungs of the OP group. The cardiac and respiratory function were better in the OP group than in the control group. The lung is the primary source of oxygen free radical attack, and the beneficial action of OP on free radical generation is almost exclusively restricted to the lung and does not apply to the heart. This result suggested that OP probably is effective in inhibiting free radical generation from the endothelium.

Adenosine Diphosphate↗

PubMed1992

Tissue-specific expression, induction, and inhibition through metabolic intermediate-complex formation of guinea pig cytochrome P450 belonging to the CYP2B subfamily.

The tissue-specific expression and induction of P450GP-1, a constitutive form of cytochrome P450 of the guinea pig classified into the CYP2B subfamily, were studied. Prior to these studies, a P450 form (P450GP-1 PB) was purified from phenobarbital-treated guinea pigs and the properties were compared with those of the P450GP-1. This form was judged to be the same as P450GP-1 existing in untreated animals by comparisons of their N-terminal amino acid sequences, peptide maps, and affinities toward anti-P450GP-1 antibody. Immunostaining of P450GP-1 revealed that the lung and small intestine as well as the liver of untreated guinea pigs contain P450GP-1, while none or only small amounts of this P450 form were observed in the kidney, heart, spleen, urinary bladder, and testis. The amount of liver P450GP-1 protein expressed in untreated guinea pigs was estimated to be 19.4% of the total cytochrome P450 and this form was increased 1.7-fold by phenobarbital treatment. Similarly, intestinal P450GP-1 was increased by phenobarbital treatment. However, lung P450GP-1 was not increased by the treatment. It was also observed that the liver P450GP-1 is induced with SKF-525A to the same extent as with phenobarbital. On the other hand, dexamethsone, p,p'-dichlorodiphenyltrichloroethane, and isosafrole showed no or only a weak ability to increase the liver P450GP-1 content. The drug-metabolizing activities in the liver microsomes of SKF-525A-pretreated guinea pigs were lower than those in phenobarbital-treated animals, although the P450GP-1 protein was induced equally by these treatments. The low activities of SKF-525A-treated animals in the drug metabolisms were attributed to the formation of the metabolic-intermediate complex between P450GP-1 and SKF-525A metabolite. These results permitted us to conclude that the tissue specificity in the expression of guinea pig P450 belonging to the CYP2B subfamily and the inducibility with chemicals are similar to those of rat CYP2B1, although the constitutive expression of guinea pig liver P450GP-1 is much higher than that of CYP2B1.

Amino Acid Sequence↗

PubMed1992

Temperature-sensitivity of the replication of rabies virus (HEP-flury strain) in BHK-21 cells. I. Alteration of viral RNA synthesis at the elevated temperature.

We investigated the nature of temperature sensitivity of the HEP strain of rabies virus. After initial incubation for appropriate period (more than 12 hr) at the permissive temperature (36-37 degrees), incubation temperature of the rabies virus infected cultures was shifted to a nonpermissive temperature (39.5-40.5 degrees). Upon the upshift, virion production was ceased, but the rate of viral RNA synthesis was greatly increased and reached almost 10 times that of 36 degrees-infection within 8-10 hr, and then the activity quickly decreased together with the onset of accelerated CPE. Little or no 42S genome-sized RNA was produced at the elevated temperature, and almost all RNAs produced in large amounts seemed to be viral mRNAs and were shown to be functional in t he cell-free translation system. Consistent with these observations, the viral ribonucleoprotein complex isolated from the temperature-upshifted culture was associated with relatively large amounts of small sized RNAs, which might reflect their increased transcriptive activity. These observations suggest that the viral RNA polymerase itself is not temperature-sensitive and the temperature-induced defect may reside in the regulatory factor which plays a role in turning on the synthesis of viral genome-sized RNA.

Cell Line↗

PubMed1992

Expression of mumps virus glycoproteins in mammalian cells from cloned cDNAs: both F and HN proteins are required for cell fusion.

Two recombinant plasmids were constructed by inserting the cDNAs of either the fusion (F) or the hemagglutinin-neuraminidase (HN) protein genes of mumps virus into the pcDL-SR alpha expression vector. Both the F and the HN proteins expressed in COS7 cells transfected with their respective recombinant plasmids were indistinguishable in terms of electrophoretic mobility from their counterparts synthesized in mumps virus-infected cells. The F protein was cleaved and expressed on the cell surface, but uncleaved forms were also detected. The expressed HN protein was transported to the cell surface and adsorbed guinea pig erythrocytes. Syncytium formation was induced when COS7 cells were transfected with both recombinant plasmid DNAs together, but not with the recombinant plasmid only carrying the F gene. This observation indicates that cell fusion mediated by mumps virus requires both the F and the HN glycoproteins.

Animals↗

PubMed1992

Molecular cloning and sequence analysis of the mumps virus gene encoding the L protein and the trailer sequence.

We have cloned and determined the nucleotide sequences of the seventh gene of the Miyahara strain of mumps virus (MuV) encoding the L protein. The L gene is 6925 nucleotides in length and contains a single long open reading frame which is capable of coding for a protein of 2261 amino acids with a calculated molecular weight of 256,571 Da. The deduced amino acid sequence of the L protein of MuV showed significant homology with those of six other paramyxoviruses, human parainfluenza type 2 virus, Newcastle disease virus, Sendai virus, measles virus, human parainfluenza type 3 virus, and human respiratory syncytial virus. The predicted MuV L protein contained distinct elements thought to be essential for RNA polymerase activity. A noncoding sequence of 24 nucleotides downstream of the presumed polyadenylation site of the L gene showed significant complementarity with the leader sequence composed of 55 nucleotide at the 3' end of the genomic RNA.

Amino Acid Sequence↗

PubMed1992

Preclinical models for human pre-embryo biopsy and genetic diagnosis. I. Efficiency and normalcy of mouse pre-embryo development after different biopsy techniques.

OBJECTIVE: To compare the usefulness of three micromanipulative methods at two different stages of pre-embryo development and to assess possible effects on postbiopsy survival and development. DESIGN: Four-cell and eight-cell mouse pre-embryos were biopsied using enucleation, aspiration, or extrusion of single blastomeres. After biopsy, pre-embryos were observed for in vitro and in vivo development. SETTING: Laboratories of The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School. PATIENTS, PARTICIPANTS: Only mice were used. INTERVENTIONS: Pre-embryo biopsy, developmental normalcy and pre-embryo transfer were studied. MAIN OUTCOME MEASURE(S): Few pre-embryos died as a result of biopsy trauma. High postbiopsy survival rates were associated with normal intrauterine and postnatal development. RESULTS: Expanded blastocyst formation rates from four-cell and eight-cell pre-embryos were 94.6%, 96.7% (controls); 80.7%, 89.1% (enucleation); 90.1%, 91.7% (aspiration); 83.1%, 91.5% (extrusion), respectively. Live birth rates at the four-cell stage were slightly lower in the enucleation group than in the blastomere aspiration and extrusion groups or controls (49.2% versus 58.8%, 56.3% and 66.7%, respectively). For the eight-cell stage, there were no differences between the groups. No developmental abnormalities were found in body or organ weights, in neonates or at 3 weeks of age, or in their subsequent ability to reproduce a second generation. CONCLUSIONS: Biopsy of mouse pre-embryos produces only a small loss of viability because of trauma and permits normal prenatal and postnatal development among surviving pre-embryos.

Animals↗

PubMed1992

Preclinical models for human pre-embryo biopsy and genetic diagnosis. II. Polymerase chain reaction amplification of deoxyribonucleic acid from single lymphoblasts and blastomeres with mutation detection.

OBJECTIVE: To demonstrate the use of the polymerase chain reaction in the amplification of deoxyribonucleic acid (DNA) from single human lymphoblasts and mouse blastomeres. Amplified target genes for diagnosis of sickle cell anemia and Tay-Sachs are shown. Similarly, the sparce fur mouse model for ornithine transcarbamylase deficiency was used as an X-linked system for demonstration of mutation detection after biopsy of a single blastomere. A new diagnostic method for the detection of the ornithine transcarbamylase mutation using the restriction enzyme Mse I is presented. Accuracy and reproducibility were assured. DESIGN: Polymerase chain reaction proficiency test for amplification from single cells was studied. Also, accuracy of mutation detection systems was demonstrated. SETTING: Laboratories of The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School. PATIENTS, PARTICIPANTS: We used the sparse fur mouse model and human blood cells. INTERVENTIONS: Pre-embryo biopsy, polymerase chain reaction amplification, and mutation detection were performed. MAIN OUTCOME MEASURES: Accuracy and reproducibility of DNA amplification without contamination, as well as efficient diagnostic analysis, from both single somatic and embryonic cells were shown. RESULTS: DNA amplification from single cells was uniformly rapid (6 to 10 hours) reproducible (n = 220) and accurate (n = 52). CONCLUSIONS: Our findings support the feasibility of clinical application for pre-embryo biopsy and genetic diagnosis of specific heritable diseases.

Amino Acid Sequence↗

PubMed1992

Treatment of vasospasm by balloon angioplasty: experimental studies and clinical experiences.

The vasodilation mode and degree of the invasion caused by balloon angioplasty were experimentally examined. Assessment by light microscopy and scanning electron microscopy demonstrated that the invasion to the implanted arterial wall, taken from a patient who died from vasospasm, was minimized by the use of the balloon under the condition at 1 atm, 10 times for 10 seconds. Furthermore, we applied angioplasty to eight patients who developed severe vasospasm after subarachnoid haemorrhage, and five showed improvement in neurophysiological (transcranial Doppler sonography), neuroradiological, and clinical examinations. In addition, blood vessels obtained from one patient who died 10 days after angioplasty, demonstrated similar findings to those of the experimental studies. It can be said that angioplasty will be one of the effective therapeutic methods to manage vasospasm when it is applied under the conditions mentioned above.

Adult↗

PubMed1992

Molecular cloning of AT1 angiotensin receptors.

Angiotensin II is the principal effector molecule of the renin-angiotensin system. Its effects are mediated by cell surface proteins termed AT receptors. On the basis of radioligand binding studies, these have been pharmacologically subdivided into two classes, termed AT1 receptors and AT2 binding sites (Chiu AT, et al, Biochem Biophys Res Commun 1989;165:196-203). AT1 receptors appear to mediate the major cardiovascular effects of angiotensin II, whereas no known physiological properties appear to be coupled to AT2 binding sites (Wong PC, et al, J Pharmacol Exp Ther 1990;255:584-592). To gain further insight into the function of AT1 receptors we have isolated rat cDNA's and genes encoding two distinct but highly similar isoforms of AT1 receptors, termed AT1a and AT1b receptors. Two cDNA's encoding the vascular AT1a receptor were isolated by an expression cloning strategy from a cDNA library prepared from vascular smooth muscle cells. The properties of the clones isolated by this approach are consistent with known pharmacological, biochemical signaling, and tissue distribution properties of AT1 receptors. Using this cDNA as a probe, a second isoform of rat AT1 receptor was isolated from a genomic library. This receptor, termed the AT1b receptor, is 95% identical in amino acid sequence and is pharmacologically indistinguishable from the AT1a receptor. However, the tissue-specific expression pattern of the AT1b gene differs significantly from that for the AT1a receptor.

Amino Acid Sequence↗

PubMed1992

Effects of adenosine on cardiac performance and phosphate compounds in microembolised guinea pig hearts.

OBJECTIVE: The excessive release of adenosine has been reported to cause hyperaemia and to attenuate ischaemic injury in microembolised hearts. The direct effects of exogenous adenosine on cardiac performance were investigated in microembolised guinea pig hearts with the simultaneous measurement of phosphate compounds. METHODS: 21 male guinea pig hearts were perfused according to the Langendorff technique and microembolism was induced by injecting microspheres. Hearts were then treated as follows: group A, adenosine 20 microM and theophylline 60 microM; group B, theophylline 60 microM; group C, saline (control). Cardiac performance was monitored and phosphate compounds were measured by 31P magnetic resonance spectroscopy. RESULTS: Group A showed a significant increase in the left ventricular developed pressure and coronary flow, and a modest restoration of ATP content. Pi/(Pi+Pcr) remained virtually constant. There were no significant changes in left ventricular developed pressure or coronary flow in groups B and C. There was a gradual decrease in tissue ATP content and slight increase in Pi/(Pi+Pcr). CONCLUSIONS: Adenosine improved cardiac performance without adverse effect on energy metabolism in microembolised hearts. Adenosine also restored the ATP stores in microembolised hearts. (Pi = inorganic phosphate; Pcr = phosphocreatine.)

Adenosine↗

PubMed1992

Silent mother-to-child transmission of hepatitis C virus through two generations determined by comparative nucleotide sequence analysis of the viral cDNA.

To investigate the routes of transmission of hepatitis C virus (HCV), a family in which HCV was considered to be transmitted from mother to child through two generations was studied. By the polymerase chain reaction method, HCV cDNA was isolated from the serum of a female baby with self-limited hepatitis C. HCV cDNA was also obtained from her mother and grandmother, who are healthy carriers of HCV, as well as from her uncle suffering from chronic persistent hepatitis C. The nucleotide sequence of the HCV cDNA fragment obtained from the baby was identical to that of the mother and was much closer to those of the grandmother and the uncle than to HCV cDNA isolates previously obtained from other Japanese patients or carriers. These results indicate the presence of mother-to-child transmission of HCV and suggest a role of this transmission route in establishing HCV carriers and maintaining a high incidence of HCV infection.

Adult↗

PubMed1992

Determination of gastroduodenal alkaline responses using pH deflection in the rat.

We set up a new system for measuring the gastroduodenal HCO3- responses using pH deflection and the potential difference (PD) in the anesthetized rat. The stomach or the proximal duodenum was perfused at a flow rate of 0.7 ml/min with saline (pH 4.5), the pH of the perfusate and PD were continuously monitored, and HCO3- output was determined as acid-neutralizing capacity by back-titration of the perfusate to pH 4.5. In the case of the stomach, acid secretion was inhibited by omeprazole (60 mg/kg i.p.). Under these conditions, the pH, PD, and HCO3- output were 5.5 +/- 0.03, -3.8 +/- 0.4 mV, and 1.5 +/- 0.3 microEq/10 min in the duodenum and 5.4 +/- 0.04, -52.4 +/- 1.8 mV, and 1.2 +/- 0.3 microEq/10 min in the stomach, respectively. In addition, when various amounts of NaHCO3 were added into the system, a linear relationship was obtained between the area of pH deflection and the amount of added HCO3- (r = 0.999). Both pH and HCO3- output in these tissues were significantly increased by intravenous administration of prostaglandin E2, carbachol, and YM-14673 (a TRH analogue); the net HCO3- output in the duodenum was 8.7 +/- 1.3, 2.3 +/- 0.5, and 5.2 +/- 0.9 microEq, respectively. The values of net HCO3- output measured by back-titration coincided well with those obtained from the area of pH deflection caused by various agents. These results indicate that this system using pH deflection may be useful for quantitative determination of HCO3- response in the gastroduodenal mucosa.

Animals↗

PubMed1992

Induction of duodenal ulcers in sensory deafferented rats following histamine infusion.

We used capsaicin as a selective probe for sensory neuronal mechanisms and examined in rats whether defunctionalization of the sensory nerves caused duodenal ulcers in the presence of acid hypersecretion. Chemical deafferentation was performed by subcutaneous injection of capsaicin for 3 days (total dose: 100 mg/kg) 2 weeks before the experiment. This treatment did not cause by itself any damage in the duodenum. However, intravenous infusion of histamine (4, 8 and 16 mg/kg/h) in these animals caused hemorrhagic lesions in the proximal duodenum within 6 h in a dose-dependent manner with an incidence of 100%. Histamine alone in the control animals did not induce macroscopically visible lesions at lower doses and caused only slight damage at the highest dose (16 mg/kg/h), although acid secretion was stimulated to the maximal degree at 8 mg/kg/h. Ablation of capsaicin-sensitive sensory neurons did not have any effect on acid secretion induced by histamine (8 mg/kg/h), but significantly inhibited the increase in duodenal HCO3- secretion in response to mucosal acidification. We conclude that functional ablation of capsaicin-sensitive sensory nerves impairs duodenal HCO3- secretory response to acid and results in duodenal ulcers if acid hypersecretion is present. These sensory nerves may be important in the defense mechanism of the duodenum against luminal acid.

Animals↗

PubMed1992

Reference values of serum and urine creatinine, and of creatinine clearance by a new enzymatic method.

A new, totally enzymatic procedure for the determination of creatinine in serum and urine, using creatinine amidohydrolase, creatine amidinohydrolase, sarcosine oxidase and formaldehyde dehydrogenase is described. The assay was adapted to a discontinuous analyser with each analysis requiring only 20 microL of serum or 3 microL of urine. Analytical recovery of creatinine in serum and urine averaged 100.6%. Within-run and between-run precision studies gave coefficients of variation of 1.1% and 1.8%, respectively, for a serum with mean values of 83 mumol/L (9.4 mg/L) creatinine. Creatinine concentrations in serum and urine were measured by this procedure, in Japanese children and adults. The reference intervals for serum creatinine concentrations in adults were 55-96 mumol/L (6.2-10.9 mg/L) in men and 40-66 mumol/L (4.5-7.5 mg/L) in women, and for urine, 9.46-19.01 mmol/day (1070-2150 mg/day) in men and 6.75-10.61 mmol/day (764-1200 mg/day) in women. The reference intervals of creatinine clearance were 88.0-176.4 mL/min in men and 75.7-173.0 mL/min in women.

Adult↗

PubMed1992

Clinical significance of reverse redistribution on thallium-201 single-photon emission computed tomography in patients with acute myocardial infarction.

To determine the clinical significance of reverse redistribution (RR), resting thallium-201 myocardial single-photon emission computed tomography was performed once or twice in 80 patients in subacute phase (1 week to 2 months) of myocardial infarction. Thirty eight patients demonstrated RR on at least one study (group RR) and 32 a fixed defect only (group FD). Group RR had significantly smaller defects than group FD. Standardizing the relation of the severity of wall motion abnormality of left ventricle on echocardiogram with that of perfusion defect, in group RR wall motion abnormality in the acute and subacute phase reflected the defect of delayed image, while that in chronic phase, which was thought to reflect the viability of myocardium in the infarct region, reflected the defect of initial image. In serial thallium-201 studies, only the defect of delayed image of group RR improved on the second study, while the defect of initial image of group RR and defect of group FD did not improve. Wall motion of group RR improved with the disappearance of RR, and when RR remained, wall motion did not improve so much. We concluded that RR was thought to be demonstrated in viable myocardium with severe wall motion abnormality.

Adult↗

PubMed1992

Extensive specifically localized myocardial calcium deposition in a hemodialysis patient.

A 51-year-old female who was hospitalized for evaluation of frequent episodes of hypotension, died unexpectedly. At autopsy, there were many fine, white granular deposits in the myocardium, which were more prominent in the subepicardium of the left ventricle than in the subendocardium. Pathologic calcification is sometimes seen in chronic hemodialysis patients and in some organs the sites of calcium deposition are quite specific. There have been few reports concerning the pattern of calcium deposition in the myocardium and, to our knowledge, the reason for this characteristic distribution is unknown. However it may relate to hydrogen ion concentration in the myocardium.

Calcinosis↗

PubMed1992

[Effect of the dry distillation tar of delipidated soybean (Glyteer) on a psoriasic model in the mouse (4)].

Effect of Glyteer (GL) on edema and epidermal hyperplasia in mouse ear by 12-o-tetradecanoylphorbol-13-acetate (TPA) were investigated by its topical application; and the effects were compared with those of betamethasone 17-valerate (BV), indomethacin (IM) and cyclosporin (CS). GL significantly inhibited the edema in mouse ear at 6 hr after TPA treatment. The inhibitory activity of GL on the edema had the same potency as those of BV, IM and CS. Furthermore, GL inhibited the epidermal weight and its protein amount on the hyperplastic response in mouse ear at 3 days after TPA treatment, and the inhibitory activity of GL was also confirmed by the pathologic findings. The mode of the inhibitory action of GL was the same as those of BV and CS, but not that of IM. From those results, it is suggested that GL possesses a potent therapeutic effect for psoriasis.

Animals↗