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Biomedical subjects

T Katoh

Publications and source records attributed to T Katoh.

At least 343 records · Page 19Linked to original sources
PubMed1993

Actin-binding peptides obtained from the C-terminal 24-kDa fragment of porcine aorta smooth muscle myosin subfragment-1 heavy chain.

The C-terminal 24-kDa fragment of myosin subfragment-1 (S-1) heavy chain was isolated by papain digestion of porcine aorta myosin followed by ethanol fractionation. The isolated 24-kDa fragment was digested by lysylendopeptidase. When the digest was ultracentrifuged with F-actin, 7- and 2-kDa peptides coprecipitated with the actin. These two peptides were isolated by high performance liquid chromatography, and their amino acid sequences were determined. The 7- and 2-kDa peptides correspond to residues 692-744 and 835-846, respectively, of the chicken gizzard myosin heavy chain (Yanagisawa, M., Hamada, Y., Katsuragawa, Y., Imamura, M., Mikawa, T., and Masaki, T. (1987) J. Mol. Biol. 198, 143-157). The 7-kDa peptide contains the reactive cysteine residues, SH1 and SH2. The isolated 7- and 2-kDa peptides also bound to F-actin with dissociation constants of 0.6 and 12 microM, respectively. The 2-kDa peptide was found to compete with rabbit skeletal S-1 for the binding to F-actin by examining the binding of S-1 to actin in the presence of various concentrations of the 2-kDa peptide. The 2-kDa peptide was also shown to interact with the regulatory light chain of aorta myosin by difference UV absorption spectroscopy. The 2-kDa peptide inhibited the actin-activated ATPase activity of skeletal S-1, and the inhibition was canceled by the addition of the isolated regulatory light chain. These results suggest that the newly found 2-kDa peptide region may be related to the regulation of smooth muscle actomyosin ATPase activity by phosphorylation of the regulatory light chain.

Actins↗
PubMed1993

Regional energy metabolism of failing hearts following myocardial infarction.

To elucidate the relationship between functional alterations and disturbances in myocardial energy metabolism of rats with heart failure following coronary artery ligation, the left coronary artery of the rat was ligated and the time course of changes in cardiac function and myocardial energy state of the animal were examined for 12 weeks after the ligation. Coronary artery ligation resulted in approximately 40% infarction of the left ventricle, an increase in the right ventricular weight, a decrease in left ventricular developed pressure, an increase in left ventricular end-diastolic pressure throughout the experiment, suggesting the development of cardiac failure after the operation. Cardiac output and stroke volume indices were not altered during the first 4 weeks, but were significantly decreased on the 8th and 12th weeks, suggesting that cardiac function had further aggravated by 8 weeks after the operation. Myocardial energy profiles of the scar tissue, the remaining left ventricle and interseptum, and the right ventricle were determined. Tissue ATP (27.54 +/- 0.82 to 26.38 +/- 1.58 mumol/g dry tissue; n = 8-10) and creatine phosphate (26.73 +/- 1.63 to 24.38 +/- 1.83 mumol/g dry tissue; n = 8-10) of the remaining viable left ventricle were lower than control (33.17 +/- 0.73 and 40.04 +/- 1.07 mumol/g dry tissue; n = 8) throughout the experiment. A marked decrease in tissue ATP and CP was seen in the scar tissue throughout the experiment. Increases in tissue lactate of the remaining left ventricle and the right ventricle were detected from 1 to 2 weeks after the operation, but returned to the control levels thereafter. Mitochondrial oxygen consumption rates of isolated myocardial bundles from the 8th and 12th weeks (21.03 +/- 2.22 and 17.79 +/- 3.24 ng oxygen/min/mg dry tissue; n = 8) were lower than control (33.15 +/- 1.95 ng oxygen/min/mg dry tissue; n = 5), and those of the interseptum (23.71 +/- 1.33 ng oxygen/min/mg dry tissue; n = 8) and the right ventricle (22.44 +/- 2.73 ng oxygen/min/mg dry tissue; n = 8) on the 12th week after the operation were lower than control (33.58 +/- 2.80 and 34.83 +/- 2.64 ng oxygen/min/mg dry tissue; n = 5). The results provide evidence for a decline in myocardial energy store and energy producing ability associated with the development of cardiac failure.

Acute Disease↗
PubMed1993

Morphine does not affect the awakening concentration of sevoflurane.

This study was designed to determine whether morphine 0.1 mg.kg-1 i.v. given intraoperatively altered the end-tidal concentration of sevoflurane which is associated with eye opening to verbal command. We studied 24 healthy ASA physical status I patients to determine whether morphine, or placebo administered about 60 min before the end of surgery affected recovery from sevoflurane/oxygen anaesthesia. During anaesthesia no other anaesthetics or drugs were given. After surgery, end-tidal sevoflurane concentration was reduced gradually at the rate of less than 0.01%.min-1. The end-tidal concentration at the time patients could respond to verbal command was recorded as MACawake. The MACawake was 0.58 +/- 0.12% (mean +/- SD) for the control group to whom placebo had been administered, and 0.57 +/- 0.11% for morphine group to whom morphine had been administered. In both groups, the MACawake decreased with age, and the ratio to age-adjusted sevoflurane MAC was 0.31 +/- 0.04 (mean +/- SD) for the control group and 0.30 +/- 0.04 for the morphine group. The ratio had no correlation with age. It is concluded that the awakening concentration of sevoflurane during recovery from anaesthesia is not affected by analgesic doses of morphine 0.1 mg.kg-1 i.v. administered intraoperatively.

Adult↗
PubMed1993

Studies on the glomerular microcirculatory actions of manidipine and its modulation of the systemic and renal effects of endothelin.

We examined the actions of intravenously administered manidipine on systemic and renal microcirculatory hemodynamics and its efficacy in antagonizing endothelin-1 (ET-1)-evoked responses. Manidipine was a potent vasodilator with preferential activity in the renal vasculature. Its administration in optimal doses resulted in decreases in systemic arterial pressures accompanied by increases in renal perfusion and filtration rates. Its primary sites of action in the kidney were at both pre- and postglomerular arteriolar sites. Manidipine was capable of near-total reversal of the sustained elevations in arterial pressure and the progressive reductions in renal blood flow and glomerular filtration rates induced by intravenously administered ET-1. In the presence of prolonged calcium channel blockade, subsequent administration of ET-1 led to paradoxic hypotensive responses, which could be profound and blocked by an inhibitor of nitric oxide synthesis. These unexpected vasorelaxant actions of ET-1 in the presence of manidipine were likely caused by the dual effects of antagonism of its own intrinsic vasoconstrictor action (through calcium channel blockade), as well as ET-1-evoked release of the endothelium-derived relaxing factor, nitric oxide.

Animals↗
PubMed1993

Evaluation of intraductal ultrasonography in the diagnosis of pancreatic cancer.

An intraductal ultrasound (IDUS) probe which is inserted via the papilla into the main pancreatic duct (MPD) was evaluated in the diagnosis of 20 patients with pancreatic cancer. The examination was successfully performed with the probe in 17 of the patients (85%). Due to its high frequency (30 MHz) the probe only allowed visualization of the ductal wall and the immediate periductal vicinity (up to about 10 mm). In 15 of the 20 patients the tumors were surgically resected and IDUS scanning was also performed in vitro on the resection specimens, the results being compared to those of histopathological examination. Of these 15 patients, 13 were found to have ductal adenocarcinomas and all but one had been unequivocally diagnosed as having such by ultrasonography (US), computed tomography (CT), endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic ultrasonography (EUS). IDUS showed an echorich area (corresponding to cancerous canaliculi on histopathological examination), surrounded by an echopoor area (abundant stroma). This pattern was classified as type I. In two patients with intraductal papillary carcinomas in whom a conclusive diagnosis was not established on US, CT, EUS or ERCP, IDUS showed tumorous tissue with an inhomogeneous echopattern outside (type II) or within (type III) the duct. These results show that IDUS offers valuable diagnostic information complementary to ERCP especially in cases of intraductal papillary tumors. Whether the high resolution imaging of the duct and the paraductal tissue can be used to differentiate between the different forms of pancreatic lesions (inflammation, neoplasms) has to be investigated further.

Adenocarcinoma↗
PubMed1993

3-Dimethylphosphinothioyl-2(3H)-oxazolone (MPTO), a promising new reagent for racemization-free couplings.

3-Dimethylphosphinothioyl-2(3H)-oxazolone (MPTO) was synthesized, and its ability to effect racemization-free couplings and cyclization of a peptide and its C-terminal epimer was examined. MPTO showed good reactivity in aprotic polar solvents such as N,N-dimethylformamide (DMF) and N-methylpyrrolidone. In reactivity MPTO resembles DPPA and dimethylphosphinothioyl azide (MPTA) previously developed by us, but it is much better than these reagents because the side reactions specific to the azide method could be avoided. In coupling of Z-Gly-Val-OH with H-Val-OMe in DMF at 0 degree C, no racemization was observed without use of racemization-suppressing additives. Slight racemization observed at room temperature could be completely suppressed by addition of HOBt but not by HOSu. The utility of MPTO was demonstrated by the synthesis of cyclo-(D-Trp-D-Glu(OBzl)-Ala-D-Val-Leu), an intermediate for an endothelin-binding inhibitor BE 18257A. In a comparative study using DPPA, MPTA and MPTO, no racemization was observed for MPTA or MPTO, while DPPA caused considerable racemization. When MPTO was used in the presence of HOBt rapid cyclization (3 h at RT) occurred to give the optically pure cyclic product.

Amino Acid Sequence↗
PubMed1993

[Detection of antibody to varicella zoster virus by immune adherence hemagglutination].

Anti varicella-zoster virus (VZV) antibodies were detected by an immune adherence hemagglutination (IAHA) test, and were compared with the CF test, IFA test and ELISA test, respectively. Type O, Rh-positive RBC for IAHA was obtained from five healthy volunteers. All five RBCs had sufficient sensitivity as the indicator cell. Optimum incubation temperature was 37 degrees C in the serum and in the complement. The complement was obtained from guinea pig sera, and the most suitable concentration was 1;100. The convalescent VZV antibody titers were similar to the values obtained from any of the methods previously mentioned. However, mean titers measured by CF were about two-to fourfold lower than in the values of IAHA. Seroconversion rates of the live VZV vaccine, as detected by CF and IFA were relatively low (CF; 76%, IFA; 56%). In contrast, those obtained from ELISA and IAHA showed perfectly (100%). These results indicate that IAHA has sufficient sensitivity and specificity in the detection of VZV antibodies. In addition, the IAHA test is thought to be a rapid and easy test to perform in ordinary laboratories.

Antibodies, Viral↗
PubMed1993

Leukotriene D4 is a mediator of proteinuria and glomerular hemodynamic abnormalities in passive Heymann nephritis.

We assessed the role of leukotrienes (LTs) in Munich-Wistar rats with passive Heymann nephritis (PHN), an animal model of human membranous nephropathy. 10 d after injection of anti-Fx1A antibody, urinary protein excretion rate (Upr) in PHN was significantly higher than that of control. Micropuncture studies demonstrated reduced single nephron plasma flow and glomerular filtration rates, increased transcapillary hydraulic pressure difference, pre- and postglomerular resistances, and decreased ultrafiltration coefficient in PHN rats. Glomerular LTB4 generation from PHN rats was increased. Administration of the 5-LO activating protein inhibitor MK886 for 10 d markedly blunted proteinuria and normalized glomerular hemodynamic abnormalities in PHN rats. An LTD4 receptor antagonist SK&F 104353 led to an immediate reduction in Upr and to reversal of glomerular hemodynamic impairment. Ia(+) cells/glomerulus were increased in PHN rats. In x-irradiated PHN rats, which developed glomerular macrophage depletion, augmented glomerular LT synthesis was abolished. Thus, in the autologous phase of PHN, LTD4 mediates glomerular hemodynamic abnormalities and a hemodynamic component of the accompanying proteinuria. The synthesis of LTD4 likely occurs directly from macrophages or from macrophage-derived LTA4, through LTC4 synthase in glomerular cells.

Animals↗
PubMed1993

Cerebral awakening concentration of sevoflurane and isoflurane predicted during slow and fast alveolar washout.

We studied 49 patients of ASA physical status I to determine cerebral anesthetic concentration on awakening calculated with end-tidal anesthetic concentration, when the end-tidal concentration decreased spontaneously. We also attempted to explain the difference in the average of the bracketing alveolar anesthetic concentration that allows and prevents the response to verbal command during recovery from anesthesia (MAC-Awake) between slow and fast alveolar washout by comparing the cerebral anesthetic concentrations with MAC-Awake determined by fast and slow washout. Slow washout was obtained by decreasing anesthetic concentrations in predetermined steps of 15 min, assuming equilibration between brain and alveolar partial pressures. Fast alveolar washout was obtained by discontinuation of the inhaled anesthetic, which had been maintained at 0.5 minimum alveolar anesthetic concentration (MAC) for at least 15 min. MAC-Awake values for sevoflurane and isoflurane obtained by slow washout were 0.34 +/- 0.05 and 0.31 +/- 0.05 (mean +/- SD), respectively, when MAC-Awake was expressed as a ratio to age-adjusted MAC. MAC-Awake values obtained by fast washout (0.22 +/- 0.07 MAC for sevoflurane, 0.22 +/- 0.05 MAC for isoflurane) were significantly smaller than those obtained by slow washout. Anesthetic concentrations in the brain at first eye opening calculated with end-tidal concentrations during fast alveolar washout (0.34 +/- 0.08 MAC for sevoflurane, 0.30 +/- 0.08 MAC for isoflurane) were nearly equal to MAC-Awake obtained by slow alveolar washout. The difference in MAC-Awake between fast and slow alveolar washout could be explained by arterial-to-cerebral and end-tidal-to-arterial anesthetic differences.

Adult↗
PubMed1993

SUT-8701, a cholecystokinin analog, prevents the cholinergic degeneration in the rat cerebral cortex following basal forebrain lesioning.

SUT-8701 is a cholecystokinin octapeptide (CCK8) analog and a more lipophilic peptide than CCK8. We previously demonstrated that intra-ventricularly administered CCK8 protected against the degeneration of the cholinergic neurons in the cortex of the nucleus basalis magnocellularis (nbm)-lesioned rat. We determined whether SUT-8701 and CCK8 have the ability to protect against cholinergic degeneration in the cerebral cortex of nbm-lesioned rats. Systemically administered SUT-8701 (0.1-1 micrograms/day/animal, s.c.) preserved choline acetyltransferase activity and K(+)-evoked acetylcholine release in nbm-lesioned rats. SUT-8701 was more potent than CCK8. However, SUT-8701 was much less potent than CCK8 in satiety action. The affinity of SUT-8701 to the cholecystokinin (CCK) receptors assessed by using [125I]-CCK8 was almost the same as that of CCK8 in the mouse cerebral cortex, but was 107 times less than that of CCK8 in guinea pig pancreas. These results suggest that SUT-8701 may be effective in slowing down the degenerative processes in Alzheimer's disease by preserving the integrity of cholinergic neurons in the nucleus basalis.

Acetylcholine↗
PubMed1993

[Abnormalities of calcium, phosphorous and vitamin D metabolism with proximal renal tubular dysfunction in subjects environmentally exposed to cadmium].

Calcium, phosphorus and vitamin D metabolism were examined in 21 male and 13 female subjects with renal tubular dysfunction in the cadmium-polluted Jinzu River basin in Toyama prefecture, Japan. Multiple proximal renal tubular dysfunction was detected in all subjects showing increased FE beta 2-m and FFua, generalized aminoaciduria and renal glucosuria. Reduced ability of tubular reabsorption of phosphate resulted in hypophosphatemia in 31% of the women. Despite decreased tubular reabsorption of calcium, the level of serum calcium remained normal in all subjects. Serum 1,25-dihydroxyvitamin-D [1,25(OH)2D], which is produced in the proximal tubules through 1 alpha-hydroxylation from 25-hydroxyvitamin-D [25OHD], was normal or increased to more than 60pg/ml. The serum level of 1,25(OH)2D was inversely related to creatinine clearance in both the men (p < 0.05) and women (p < 0.01). Serum iPTH was slightly increased to more than 0.9 mg/ml, whereas the levels of other hormones, including 25OHD, calcitonin, thyroxine (T4) and triiodothyronine (T3) were normal. The serum alkaline phosphatase activity and serum osteocalcin concentration were significantly increased compared to those of controls in both sexes. Bone loss detected by the measurement of bone density was prominent in female subjects. These results support the hypothesis that the serum phosphate concentration is more important than the serum concentration of 1,25(OH)2D for abnormalities of bone metabolism in cadmium-induced renal tubular dysfunction.

Aged↗
PubMed1993

[Effects of methyl tertiary-butyl ether on hepatic lipid peroxidation in mice].

The effect of one-shot or repeated treatment with methyl tertiary-butyl ether (MTBE) on lipid peroxidation and cytochrome P-450 in mouse liver was examined. One-shot treatment at the 500 mg/kg dose level caused a transient decrease in leukocyte number after 24 h. An increased level of lipid peroxide was observed in the liver homogenates 24 h after one-shot treatment and four weeks of repeated 200 mg/kg treatment. The hepatic cytochrome P-450 content increased after one and four weeks of repeated treatment (50, 200 mg/kg). On the other hand, the treatment did not affect glutathione content and glutathione-S-transferase activity. These results indicate that MTBE treatment caused lipid peroxidation in the liver homogenate and induction of hepatic microsomal cytochrome P-450 content.

Animals↗
PubMed1993

MR imaging of vascular compression in hemifacial spasm.

Hemifacial spasm is related to vascular compression of the root entry zone of the facial nerve at the brainstem by elongated tortuous vessels of the vertebrobasilar arterial system. In this study, we performed MR imaging in 16 patients with hemifacial spasm and investigated the vascular structures in bilateral-cerebellopontine angles and the relationship of each vessel to the root entry zone of the facial nerve. MR examination was performed with a 0.5 tesla MRI system, and MR angiography (3D time-of-flight) was obtained. Of 15 patients in whom both the nerve and vessels were clearly visible and could be observed to contact each other at the root entry zone, in 11 the tortuous artery could be identified by name. In only 1 patient was the contact between the nerve and vessel indeterminate, due to nonvisualization of the vessel around the facial nerve at its root entry zone. These findings suggest that MRI is a useful screening method in the preoperative assessment of hemifacial spasm.

Adult↗
PubMed1993

Enhanced MRI in patients with Ramsay-Hunt's syndrome.

Enhanced MRI was performed in 14 patients with Ramsay-Hunt's syndrome to investigate the pathogenesis of this syndrome. All MRI studies were performed on a 0.5T superconductivity MRI system using a head coil with Gd-DTPA. Enhancement was observed in the areas of the distal internal auditory canal and labyrinthine segment in many patients, and was especially prominent in patients suffering from vertigo, tinnitus, and hearing loss. In some patients it involved not only the facial nerve of the internal auditory canal but also the cochlear nerve and vestibular nerves. Since histological changes of the facial nerve in patients with Ramsay-Hunt's syndrome are assumed to occur in the distal internal auditory canal and labyrinthine segment, which is more proximal than the geniculate ganglion, and the possibility is suggested that inflammation may spread to the vestibular and cochlear nerve via the internal auditory canal.

Aged↗
PubMed1993

[Gadolinium-DTPA magnetic resonance imaging in the diagnosis of left atrial myxoma in the elderly].

A 85-year-old woman consulted our hospital with general fatigue, palpitation and chest discomfort changing with different postures. Her electrocardiogram showed sinus tachycardia, atrial premature beats and left atrial overload. 53% cardiothoracic ratio, slightly protruding third arch of the cardiac silhouette and dilated pulmonary artery were seen on the chest X-ray. Two dimensional echocardiography revealed a mass in the left atrium although the quality of echocardiography was suboptimal due to her thoracic deformity. There was no uptake of T1-201 or Ga-67 by the mass. The four-chamber view of Tc-99m ECG-gated SPECT radionuclide angiocardiography showed a filling defect in the left atrium. The T1 weighted magnetic resonance imaging revealed a left atrial mass with relatively low signal intensity. After intravenous injection of Gadolinium-DTPA the signal intensity of the mass increased significantly and the contrast of the mass was improved. The size of the mass was 4 x 4 x 3 cm with a stalk connecting to the interatrial septum. These findings were compatible with left atrial myxoma. Gadolinium-DTPA magnetic resonance imaging is useful in diagnosing left atrial myxoma because it provides information on the size, anatomical location, relationship with other cardiovascular structures and even the characteristics of the mass.

Aged↗
PubMed1993

Electrical pelvic floor stimulation in the management of urinary incontinence due to neuropathic overactive bladder.

Electrical pelvic floor stimulation employing a portable functional electrical stimulation system with percutaneously indwelling electrodes was carried out to improve detrusor urinary incontinence. Cyclic stimulation using negative going pulse trains of 20 Hz was applied 3 to 6 times daily to the bilateral pudendal nerves distributing to the pelvic floor muscles for the purpose of strengthening these muscles, including the urethral sphincter, and simultaneously, suppressing detrusor overactivity and increasing cystometric capacity. Electrical training for 4-8 weeks resulted in an improvement of urinary incontinence in five of six patients. In two of six cases incontinence had subjectively disappeared. Urodynamic investigations demonstrated an increase in detrusor reflex threshold and less tendency for abortive detrusor contraction. No apparent complications were encountered during these periods. This procedure appears to be efficient for the management of patients with detrusor incontinence who respond poorly to conservative therapies.

Adult↗