Search PubMed⌕ Search

Biomedical subjects

K Munakata

Publications and source records attributed to K Munakata.

At least 55 records · Page 3Linked to original sources
PubMed1995

Significance of the right ventricular free wall in dogs with and without pulmonary constriction.

To evaluate the role of the right ventricular (RV) free wall in cardiac function, RV and left ventricular (LV) wall segment lengths were measured by ultrasonic crystals in 10 open chest dogs with the pericardium preserved. Right coronary artery (RCA) was perfused separately by own blood and the flow was reduced stepwise until active shortening (delta L) of the RV segment disappeared or RCA flow became zero (Ischemia). The experiment was repeated with and without pulmonary stenosis (PS). At Ischemia, RV and LV systolic pressures decreased. RV end-diastolic length increased and RV delta L decreased. LV end-diastolic length and LV delta L were reduced. LV stroke volume concurrently fell. These changes became more prominent with PS. The critical level of RCA flow, at which RV delta L began to change, was higher with PS (5.27 +/- 2.85 ml/min, mean +/- S.D.) than without PS (1.44 +/- 1.16, p < 0.01). Based on the relationships between RV delta L and percent changes in RV developed pressure and stroke volume, the degree of the decreases in RV developed pressure and stroke volume at RV delta L of zero were estimated to be about 20%. These results indicate that the RV free wall partly contributes to maintaining the RV function, especially during RV pressure overload.

Animals↗
PubMed1995

[ECG-gated dual isotope myocardial SPECT with 99mTc-MIBI and 123I-BMIPP in patients with ischemic heart disease].

Simultaneous dual-isotope SPECT with 99mTc-methoxy isobutyl isonitrile (MIBI) and 123I-beta-methyl iodophenyl-pentadecanoic acid (BMIPP) was performed in 25 patients with ischemic heart disease. ECG-gated myocardial SPECT was acquired following the injection of MIBI (555 MBq) and BMIPP (148 MBq). Both MIBI and BMIPP scans provided high-quality myocardial images. Then, myocardial count increase rate (%WT = ES-ED/ED x 100) was calculated as an index of left ventricular contraction using MIBI gated SPECT data. The %WT was well correlated with severity scores of both MIBI image (r = -0.70) and BMIPP image (r = -0.72). Thus, ECG-gated dual-isotope SPECT with MIBI and BMIPP was considered to be useful method for assessment of left ventricular contraction as well as myocardial perfusion and fatty acid metabolism.

Aged↗
PubMed1995

[Low-dose dobutamine stress test for the evaluation of cardiac function using ECG-gated SPECT scintigraphy with 99mTc-MIBI].

Although 201TlCl myocardial scintigraphy has so far been widely used for the evaluation of the viability of the myocardial infarcted area, functional evaluation using low dose dobutamine (DOB) loaded echography also became recently available. We performed 99mTc-mIBI gated SPECT on eight cases of myocardial infarction at rest and low dose (4-6 micrograms/kg/min) DOB-loading and related data were collected. Next, we calculated myocardial count increase rate (% WT = ES-ED/ED x 100) with left ventricular contraction from end-diastolic (ED) and end-systolic (ES) pictures in short-axial image, and made a comparative examination of regional contractilities at rest and DOB-loading. DOB-loaded echography performed on the same cases at the same dose revealed 15 segments as infarcted area (WM (+)) presenting improvement in wall movement at loading and 5 segments as infarcted area (WM (-)) presenting no such improvement, and %WT at rest and loading were 29.1 +/- 6.2 and 33.2 +/- 2.4 for (WM (-)) and 26.8 +/- 9.8 and 40.0 +/- 12.3 for (WM (+)), indicating a significant increase (p < 0.05) at loading. Contractility analysis using MIBI gated SPECT in combined use of DOB-loading was considered as a useful method of examination in view of its reflectability in the evaluation of the wall movement in DOB-loaded echography and of its high quantitativity.

Aged↗
PubMed1994

Peptidergic nerves in Hirschsprung's disease and its allied disorders.

To clarify the significance of peptidergic nerves in Hirschsprung's disease (aganglionosis), hypoganglionosis, and neuronal intestinal dysplasia (NID), we investigated enteric nerve responses in colonic tissues obtained from patients with these diseases. Colonic tissue specimens were obtained from 12 patients with aganglionosis, 8 patients with hypoganglionosis, and 6 patients with NID. Colon specimens from 20 patients without constipation were used as controls. A mechanograph was used to evaluate in vitro colonic responses to electrical field stimulation (EFS) of the adrenergic and cholinergic nerve blockers and gastrointestinal hormones. The following results were obtained: (1) Non-adrenergic inhibitory nerves were found to act on the normal human colon and to a lesser extent in colons with hypoganglionosis or NID, but had no effect on the enteric nerves in colons with aganglionosis. (2) Peptidergic neurotransmitters such as VIP, substance P, and neurotensin apparently act in the normal human colon, and to a lesser extent in the colons with hypoganglionosis or NID, but their effect was almost absent in aganglionosis. (3) VIP acts via neural mechanisms, while substance P and neurotensin may act both via nerves and also directly on the bowel smooth muscle. The diminution of action of non-adrenergic inhibitory nerves and peptidergic nerves may be largely related to the impaired motility observed in hypoganglionosis, NID and aganglionosis.

Adolescent↗
PubMed1994

Efficacy of a novel injectable cephalosporin, Cefclidin, on the experimental complicated urinary tract infections with urinary stones caused by Pseudomonas aeruginosa and Proteus mirabilis.

We evaluated the effects of a novel cephalosporin, cefclidin (CFCL) and imipenem (IPM), on the eradication of bacteria from the urine, bladder stones and the kidneys, and also on the prevention of the infection stone formations, in our polymicrobial urinary tract infection model of rats associated with bladder stones using IMP-sensitive or IPM-resistant Pseudomonas aeruginosa and Proteus mirabilis as a causative pathogen. CFCL completely eradicated P. mirabilis from the urine and the stone in the short-term regimen (5 days). CFCL completely eradicated both IPM-sensitive P. aeruginosa and P. mirabilis from the urine, the stones and the kidneys as compared to IPM in the long-term regimen (11 days), reflecting the superior antibacterial activity of CFCL. CFCL also significantly prevented the development of infection stones as compared to IPM in the long-term regimen. There was no significant difference in the blood urea nitrogen (BUN) values between the CFCL or IPM-treated and the non-treated groups. The cumulative recovery rate of unchanged CFCL reached 47.3% of the total dosage (20 mg/kg) within 8 hours.

Animals↗
PubMed1993

High-level production and secretion of a mouse-human chimeric Fab fragment with specificity to human carcino embryonic antigen in Escherichia coli.

A high-level secretion system for the production of mouse-human chimeric antibody 21B2 (MHC 21B2) Fab fragment specific for human carcino embryonic antigen (hCEA) in Escherichia coli has been constructed. The genes encoding a light chain and an Fd fragment (a variable region and the CH1 domain of a heavy chain) of a mouse-human chimeric antibody were directly fused to the signal peptide of the E. coli ompF gene sequence. E. coli cells containing expression vectors in which each of the two genes are located downstream of a separate tac promoter were able to secrete the light chain and Fd fragment as two of their major cellular proteins. The signal peptides were efficiently removed from the primary products by post-translational processing, although they formed insoluble aggregates, possibly in the periplasm. In high-cell-density culture experiments using a jar fermentor, the amount of light chain and Fd fragment produced was at levels of up to 2.88 g/l and 1.28 g/l culture, respectively. By optimizing the conditions that encourage correct folding, formation of disulphide bonds, and association of the light chain with the Fd fragment, we have established a procedure that can purify, re-fold, and combine aggregated products to electrophoretically homogeneous Fab fragment with a yield of approximately 47%. Fab fragment produced in this manner shows essentially the same antigen-binding activity and specificity to hCEA as the parental mouse antibody 21B2 (MoAb 21B2).

Amino Acid Sequence↗
PubMed1993

Modification of regional myocardial performance caused by blood withdrawal and infusion in acute ischaemic canine heart.

The effect of changes in preload on regional myocardial motion in acute ischaemia was examined by miniature ultrasonic gauges after left anterior descending coronary artery occlusion in eight open chest dogs with the pericardium preserved. Left ventricular end-diastolic pressure was varied by blood withdrawal and infusion. When preload changed, isovolumetric shortening in the non-ischaemic region was inversely related to that in the ischaemic region. When preload decreased, stroke volume decreased and was accompanied by a decrease in end-diastolic length and ejection shortening in the non-ischaemic region together with an increase in isovolumetric bulging in the ischaemic region. When preload increased, these variables changed in opposite directions. These results indicate that in acute ischaemia: (1) changes in isovolumetric shortening in the non-ischaemic and ischaemic regions were related with each other when the level of volume expansion varied, and suggest that; (2) stroke volume is affected by end-diastolic length, ejection shortening in the non-ischaemic region and isovolumetric bulging in the ischemic region.

Animals↗
PubMed1993

Unusual inferior vena cava obstruction causing extensive thrombosis: an intravascular endoscopic observation.

A 28-year-old, previously healthy man was referred to our hospital three months after the appearance of lumbago, leg pains and fever. Routine examinations were normal. Phlebography demonstrated occlusion of the common femoral veins by thrombosis. Inferior vena cavography and magnetic resonance image showed that the inferior vena cava (IVC) became gradually narrower from the level of 11th thoracic vertebra. An intravascular endoscopic study gave the same morphological findings; the endothelial surface was found to be intact. We concluded that the stenosis of the IVC was the primary lesion and was the essential pathological condition. The massive thrombosis appeared to have occurred secondarily.

Adult↗
PubMed1993

[Assessment of myocardial perfusion and left ventricular function with 99mTc-PPN 1011].

First-pass radionuclide angiography (FPRNA) was performed with the new myocardial perfusion agent 99mTc-1,2,bis[bis(2-ethoxyethyl)phosphino] ethane (99mTc-PPN 1011) on stress and at rest. One hour after that, myocardial perfusion was counted by 99mTc-PPN 1011 SPECT. Left ventricular ejection fraction (LVEF) obtained by FPRNA correlated with that by multigated image with 99mTc-HSAD (r = 0.94, n = 11). The reduction of left ventricular function under the exercise (delta LVEF) and the increase of severity score (delta Severity score) have a good relation (r = 0.88) in 7 patients with prior myocardial infarction. Thus 99mTc-PPN 1011 appears to be an ideal radiopharmaceutical for evaluation of ventricular function and myocardial perfusion.

Aged↗
PubMed1992

Evaluation of the usefulness of a novel injectable cephalosporin, E1040, and ceftazidime for management of complicated urinary tract infections caused by Pseudomonas aeruginosa and Proteus mirabilis by using the rat urolithiasis model.

A novel injectable cephalosporin, E1040, significantly eradicated Pseudomonas aeruginosa from the urine, in contrast to ceftazidime, in rats with complicated P. aeruginosa urinary tract infections associated with urinary stones, suggesting that E1040 is a prospective therapeutic agent in the management of refractory Pseudomonas urinary tract infections.

Animals↗
PubMed1992

Two cases of variant form angina pectoris associated with myocardial bridge--a possible relationship among coronary vasospasm, atherosclerosis and myocardial bridge.

Myocardial bridge (MB) is a congenital anomaly of the coronary artery and may occur in 5 to 12% of the human population. However, the mechanism of MB-induced myocardial ischemia is still speculative. We report 2 cases of variant form angina pectoris associated with MB in which myocardial ischemia seemed to be related to the interaction between coronary perfusion and MB. In case 1, electrocardiography during anginal attack at rest showed ST elevation in the inferior leads and MB was observed after percutaneous transluminal coronary angioplasty at the site of the right coronary artery lesion following successful dilatation. In case 2, MB of the left anterior descending coronary was located in the identical portion where coronary vasospasm was induced by intracoronary acetylcholine injection, although ischemia during the spontaneous anginal attack was limited to the inferior area of myocardium. These 2 cases suggest that MB can be, at least in some patients, one of the possible causes of the endothelial damage which seems to be related to coronary vasospasm; this was documented in both cases.

Angina Pectoris, Variant↗
PubMed1991

Evaluation of effects of novel urease inhibitor, N-(pivaloyl)glycinohydroxamic acid on the formation of an infection bladder stone using a newly designed urolithiasis model in rats.

By using our new infection stone model of a rat, we evaluated the effect of a novel urease inhibitor, N-(pivaloyl)glycinohydroxamic acid (P-GHA), on the formation of an infection bladder stone. The oral dosing of P-GHA significantly inhibited the elevation of the urinary ammonia level of rats having the urinary tract infection with Proteus mirabilis. A short term regimen (7 d, 730 +/- 38 mg/kg) with P-GHA significantly inhibited the development of the infection bladder stone. Furthermore, a long term combination regimen (11 d) of P-GHA and aminobenzylpenicillin markedly inhibited the development of the infection bladder stone, and also caused a very slight renal impairment to the rats tested in contrast with the method of Vermeulen et al. Our infection stone model in rats, therefore, seems to be useful for the evaluation of therapeutic agents in long term examinations.

Ampicillin↗
PubMed1991

Effects of a novel urease inhibitor, N-(diaminophosphinyl)isopentenoylamide on the infection stone in rats.

We evaluated the effect of a novel potent urease inhibitor, N-(diaminophosphinyl)isopentenoylamide (IPA), on the development of an infection bladder stone using our urolithiasis model in rats. IPA was excreted into urine after oral administration to rats, and the cumulative urinary recovery rate of unchanged IPA reached about 29.6% within 24 h (50 mg/kg). The oral administration of IPA (6.25 mg/kg, b.i.d., 5 d) significantly inhibited the development of the infection bladder stone. The present result suggests that IPA is a very promising compound in the prevention of formation and recurrence of an infection stone owing to a high efficacy and a low toxicity of IPA in animals.

Animals↗
PubMed1991

Effect of pericardium on regional myocardial systolic function in acute ischemia.

To know whether or not the pericardium affects regional myocardial systolic function in acute ischemia, we measured ischemic and non-ischemic segment lengths of the left ventricle using ultrasonic crystals in 10 open-chest dogs with the pericardium preserved. When the left ventricular pressure and segment lengths were stable after left circumflex coronary occlusion, we opened the pericardium widely. After coronary occlusion, end-diastolic length (EDL) in ischemic and non-ischemic segments increased, and the ischemic segment showed paradoxical systolic expansion while the non-ischemic segment increased its active shortening. After pericardiectomy, heart rate, left ventricular systolic pressure, and peak positive and negative dP/dt did not change. EDL in ischemic and non-ischemic segments further increased from 12.02 +/- 0.18 to 12.50 +/- 0.16 mm (mean +/- S.E., p less than 0.01) and from 11.12 +/- 0.20 to 11.45 +/- 0.18 mm (p less than 0.05), respectively, despite the concomitant fall in left ventricular end-diastolic pressure (LVEDP) from 12.4 +/- 0.6 to 10.6 +/- 0.8 mmHg (p less than 0.01). End-systolic length in ischemic and non-ischemic segments also increased from 12.37 +/- 0.25 to 12.70 +/- 0.20 mm (p less than 0.05) and from 8.50 +/- 0.13 to 8.74 +/- 0.13 mm (p less than 0.01), respectively, although the left ventricular end-systolic pressure did not change. Maximum expanded systolic length of the ischemic segment also increased from 12.99 +/- 0.20 to 13.42 +/- 0.16 mm (p less than 0.01). These results indicate that, in acute ischemia, the pericardium inhibits paradoxical systolic expansion of the ischemic region and increase in end-systolic length of non-ischemic segment. Thus, it is concluded that the pericardium modifies the regional myocardial systolic function in acute ischemia, perhaps through the mechanical restraint of the pericardium.

Animals↗