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Biomedical subjects

H Itoh

Publications and source records attributed to H Itoh.

At least 991 records · Page 55Linked to original sources
PubMed1992

Centrifugal blood pump with a magnetically suspended impeller.

A centrifugal blood pump with a magnetically suspended impeller has been developed. It has a single inlet and outlet, and it generates centrifugal forces by the rotating impeller. The fluid-dynamical design for inflow and outflow through the impeller leads to elimination of the axial force and unbalanced radial force acting on the impeller. Consequently, three-component control systems, instead of five-component ones, are enough to position the impeller. The magnetically suspended impeller rotates by the magnetic coupling with the permanent magnets embedded in the outer rotator of the motor. This pump has enough performance to function as a blood pump. Further research on the null-power magnetic suspension and the generation of an efficient rotating magnetic field is in progress.

Equipment Design↗
PubMed1992

Extracellular matrix formation in piecemeal necrosis: immunoelectron microscopic study.

Immunolocalization of Type I, Type III and Type IV collagens, laminin and prolyl hydroxylase (PH), a key enzyme in collagen synthesis, was examined to clarify the fibrotic process in chronic, active liver disease. In piecemeal necrosis of chronic, active hepatitis (CAH) and active liver cirrhosis (LC), fat-storing cells (FSCs) and transitional cells (TSCs), containing abundant rough endoplasmic reticulum (RER), were increased in number and stained intensely for PH. Immunodeposits of extracellular matrix (ECM) components were found in the RER, Golgi apparatus (GA) and vesicles of these cells, especially in cases with marked inflammation. On the other hand, in the periportal areas of chronic, persistent hepatitis (CPH) or inactive LC, immunoreaction of ECM components was seldom found in the RER of FSCs and TSCs. In the portal tract, immunodeposits of ECM components were seldom found in the organelles of fibroblasts, although ECM was increased there. These findings indicate that FSCs and TSCs in piecemeal necrosis might play a role in the production of ECM components in the progression of fibrosis during the development of chronic active liver disease. In addition, ECM component production by FSCs and TSCs is associated with marked inflammation.

Collagen↗
PubMed1992

Usual interstitial pneumonia: histologic correlation with high-resolution CT.

The authors reviewed 46 cases of idiopathic pulmonary fibrosis with usual interstitial pneumonia (UIP), correlating findings on high-resolution computed tomographic (HRCT) scans with findings in specimens obtained at open lung biopsy and autopsy. The following HRCT findings were observed: (a) an accumulation of small cystic spaces with thick walls, (b) air bronchiolograms within areas of intense lung attenuation, (c) rugged pleural surfaces, (d) irregularly thickened pulmonary vessels, (e) bronchial wall thickening, and (f) slightly increased lung attenuation. Macroscopic honeycombing correlating with small cystic spaces was demonstrated at HRCT and pathologic examination. Air bronchiolograms in the areas of intense lung attenuation (ie, microscopic honeycombing) corresponded to dilated bronchioles (greater than 1 mm in diameter) with fibrosis. Irregularly thickened vessels and bronchial walls and irregular pleural surfaces were the result of fibrosis in the periphery of the secondary pulmonary lobules. Areas of slightly increased lung attenuation seen on the HRCT scans correlated with patchy alveolar septal fibrosis or inflammation. The authors conclude that microscopic honeycombing and a perilobular distribution in UIP may be clearly identified with HRCT.

Adult↗
PubMed1992

Diffuse panbronchiolitis: correlation of high-resolution CT and pathologic findings.

Diffuse panbronchiolitis (DPB) is characterized by chronic airflow limitation and airway inflammation with bronchiolar lesions. Chest radiographs of patients with DPB usually show small nodular shadows throughout both lungs. The authors investigated the nature and pathogenesis of the radiologic features of DPB by correlating high-resolution computed tomographic (HRCT) findings with histopathologic features. The HRCT images of nine patients with DPB were compared with the observations made with inflated lung specimens. The HRCT findings of DPB included centrilobularly distributed, small rounded areas of attenuation; branched linear areas of attenuation, contiguous with the small rounded areas; dilated airways with thick walls, also common outside secondary pulmonary lobules; and decreased lung attenuation in peripheral areas due to air trapping caused by bronchiolar narrowing in the subpleural zones. The authors believe that HRCT best demonstrates this characteristic location of small rounded areas of attenuation associated with dilated airways.

Adult↗
PubMed1992

Hemodynamic effects and pharmacokinetics of long-term therapy with ibopamine in patients with chronic heart failure.

To evaluate the attenuation of the effectiveness of long-term ibopamine therapy, ibopamine was administered in single doses of 100 and 200 mg to 10 patients with chronic heart disease. The hemodynamic studies using Swan-Ganz catheter and pharmacokinetic studies were carried out. Ibopamine was found to increase cardiac output and stroke index and to decrease systemic vascular resistance in this acute study. Six patients underwent long-term therapy with the drug and were evaluated for the development of tolerance. Three out of 5 patients experienced an improvement in NYHA functional class after 12-23 weeks of treatment. There was no attenuation in the effects of ibopamine on hemodynamics, pharmacokinetic parameters remained almost unchanged, and tolerance was not observed. These results suggest that ibopamine is useful as an orally administered anti-heart failure drug.

Administration, Oral↗
PubMed1992

Cardiac output-O2 uptake relation during incremental exercise in patients with previous myocardial infarction.

BACKGROUND: The cardiac output-O2 uptake (VO2) relation, which is thought to be linear and predictable in normal humans, has not been clarified in cardiac patients. We evaluated the relation between cardiac output and VO2 during the incremental exercise test in patients with previous myocardial infarction. METHODS AND RESULTS: Twenty-two patients (age, 58.1 +/- 8.0 years) with previous myocardial infarction performed a symptom-limited exercise test on a cycle ergometer. VO2 was calculated from the expired gas analysis, and cardiac output was measured by a computerized cadmium telluride detector every 10 seconds during exercise. The ratio of increase in VO2 to the increase in work rate (delta VO2/delta WR) below and above the anaerobic threshold (AT) was 11.1 +/- 3.6 and 11.1 +/- 2.9 ml/min/W, respectively, showing no significant difference. However, the ratio of increase in cardiac output to increase in work rate (delta CO/delta WR) below the AT was 50.1 +/- 26.6 ml/min/W and was significantly decreased to 11.8 +/- 25.3 ml/min/W above the AT (p = 0.0002). The decreased delta CO/delta WR above the AT primarily would be due to silent myocardial ischemia produced by exercise, as there was the presence of 201Tl redistribution in 15 of 16 patients in whom myocardial 201Tl scintigraphy with dipyridamole or exercise stress testing was evaluated. delta CO/delta VO2, which has been reported to be approximately 5.5 in normal subjects, was only 4.4 +/- 2.6 at work rates below the AT and was decreased to 1.1 +/- 2.3 at work rates above the AT. CONCLUSIONS: The relation between cardiac output and VO2 during exercise in patients with previous myocardial infarction differs profoundly from that reported in normal subjects. These findings must be considered when we noninvasively estimate the change in cardiac output during exercise by obtaining VO2 in patients with coronary artery disease.

Adult↗
PubMed1992

Atrial natriuretic polypeptide as a novel antigrowth factor of endothelial cells.

The migration and proliferation of endothelial cells play a pivotal role in various vascular diseases. We have previously reported that atrial natriuretic polypeptide (ANP) exerts an antigrowth effect on vascular smooth muscle cells via the guanylate cyclase-coupled mechanism. Because the endothelial cells are known to possess a large number of guanylate cyclase-coupled ANP receptors, we examined the action of ANP on the growth of endothelial cells. ANP (10(-7) and 10(-6) M) significantly attenuated serum-stimulated DNA synthesis of cultured bovine aortic endothelial cells with concomitant reduction of the increase in cell number. A ring-deleted analogue of ANP exerted less prominent antiproliferative action, and 8-bromo cyclic GMP (cGMP) mimicked the action of ANP, suggesting the involvement of cGMP cascade in the endothelial growth. Moreover, the proliferative action of exogenously administered basic fibroblast growth factor on endothelial cells was significantly attenuated by the simultaneously administered 8-bromo cGMP. Taken together, the present results demonstrate a potential novel role of ANP in the regulation of endothelial cell growth, which is implicated in angiogenesis or reendothelialization.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1992

Endothelial production of C-type natriuretic peptide and its marked augmentation by transforming growth factor-beta. Possible existence of "vascular natriuretic peptide system".

C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, is thus far known to be distributed mainly in the central nervous system and is considered to act as a neuropeptide, in contrast to atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), which act as cardiac hormones. Recently, we and others have demonstrated that the ANP-B receptor, which is selectively activated by CNP, is localized not only in the central nervous system but in peripheral tissues, including blood vessels. This finding has made us speculate regarding the peripheral production of CNP. In the present study, cultured endothelial cells were examined for CNP production by RIA and Northern blot analysis. CNP-like immunoreactivity was detected in the conditioned media of endothelial cells. Northern blot analysis detected CNPmRNA with a size of 1.2 kb. In addition, transforming growth factor (TGF)-beta, one of the key growth factors for vascular remodeling, markedly stimulated the expression of CNPmRNA and induced a tremendous increase in CNP secretion. We could also detect CNP transcript in the bovine thoracic aorta using the reverse transcription-polymerase chain reaction method. The present study demonstrates the endothelial production of CNP and suggests that a member of the natriuretic peptide family may act as a local regulator in vascular walls. Since evidence for the pathophysiological importance of the vascular renin-angiotensin system has been accumulating and the natriuretic peptide system is known to be antagonistic to the renin-angiotensin system, the possible existence of "vascular natriuretic peptide system" may prove to be of physiological and clinical relevance.

Animals↗
PubMed1992

Solitary eosinophilic granuloma in the frontal lobe: case report.

A rare case of a solitary eosinophilic granuloma in the brain is reported. The mass, located in the right frontal lobe, mimicked a glioma not only grossly, but also by neuroimaging. The lesion was confirmed to be an eosinophilic granuloma by electron microscopy and immunohistochemical staining for S-100 protein and HLA-DR.

Biomarkers↗
PubMed1992

Studies on antiulcer drugs. III. Synthesis and antiulcer activities of imidazo[1,2-a]pyridinylethylbenzoxazoles and related compounds. A novel class of histamine H2-receptor antagonists.

A series of imidazo[1,2-a]pyridinylalkylbenzoxazole derivatives was synthesized and tested for histamine H2-receptor antagonist, gastric antisecretory and antiulcer activities. Some of 2-amino-6-[2-(imidazo[1,2-a]pyridin-2-yl)ethyl]benzoxazole derivatives were found to have good pharmacological activities. Among them, 2-amino-6-[2-(7-methoxy-3-methylimidazo[1,2-a]pyridin-2-yl)ethyl] benzoxazole (II-11) and 2-acetamido-6-[2-(7-methylimidazo[1,2-a]pyridin-2-yl)ethyl] benzoxazole (II-38) showed potent antisecretory and cytoprotective activity. The structure-activity relationships of these compounds are discussed.

Animals↗
PubMed1992

Studies on antiulcer drugs. VI. 4-Furyl-2-guanidinothiazoles and related compounds as potent histamine H2-receptor antagonists.

A series of 4-furyl-2-guanidinothiazole derivatives and related compounds were synthesized and evaluated for histamine H2-receptor antagonist and gastric acid antisecretory activities. Among them, compounds I-17, I-48 and I-49 showed high activities in these tests. In addition, compound I-17 possessed potent inhibitory activities on each of the gastric ulcers induced by stress, ethanol and HCl-aspirin. On the other hand, compound I-48 demonstrated antimicrobial activity against Helicobacter Pylori and the potency was far stronger than that of clinically used H2-antagonists. Some structure-activity relationships are discussed.

Animals↗
PubMed1992

Changes in oxygen uptake-work rate relationship as a compensatory mechanism in patients with heart failure.

To assess the compensatory change in oxygen uptake (VO2) kinetics during exercise in patients with heart failure, we performed cardiopulmonary exercise testing using a cycle ergometer in 29 cardiac patients and 18 normal subjects. The work rate increased linearly (1w/6sec) after a 4 min, 20w warm-up. The ratio of increase in VO2 to increase in work rate (delta VO2/delta WR) was determined by linear regression of VO2 plots. Cardiac output by dye dilution method and plasma norepinephrine concentration (NE) were measured at rest and 20w warm-up. VO2 at rest and at 20w warm-up and delta VO2/delta WR decreased significantly with increasing severity in NYHA functional classification. delta VO2/delta WR showed significant negative correlation to the difference in NE levels at rest and at 20w (r = -0.69, p less than 0.001). The delta values of arteriovenous O2 content difference, calculated using Fick's principle, and cardiac index from rest to 20w warm-up failed to show significant relationship to delta VO2/delta WR. These results suggest that the decrease in VO2 requirement in heart failure patients is due probably to blood redistribution during exercise as a compensatory mechanism for exercise intolerance.

Adolescent↗
PubMed1992

Role of sympathetic nerve inhibition in the vasodepressor effect of bromocriptine in normotensive and hypertensive rats.

This study aimed to elucidate the mechanism of the hypotensive effect of bromocriptine (BRC), and to investigate whether or not the effects of BRC on the sympathetic nervous system are altered in hypertension. BRC was administered intravenously to normotensive and spontaneously hypertensive rats (SHR). It elicited hypotensive effects dose-dependently in urethane-anaesthetized normotensive rats, an effect which was antagonized with metoclopramide. Pretreatment with intravenous hexamethonium attenuated the hypotensive effect of BRC. BRC decreased plasma norepinephrine (NE) without inhibiting the sympathetic nerve spikes recorded from the postganglionic sympathetic nerve bundle. The hypotensive effect of BRC was significantly greater in SHR than in Wistar Kyoto Rats (WKY). Decrease in NE by BRC was also significantly greater in SHR than in WKY. These results suggest that the hypotensive effect of BRC is induced by suppression of NE release, not by inhibition of sympathetic nerve spikes, and that the dopaminergic presynaptic inhibition is attenuated in SHR.

Animals↗
PubMed1992

Listeric septicemia with meningitis in a neonatal calf.

A 9-days-old calf which had exhibited depression and difficulty to stand and walk was examined pathologically and bacteriologically. The primary pathological changes consisted of multifocal necrosis in several visceral organs and fibrinopurulent meningitis. The necrotic lesions were most frequently found in the liver, and accompanied with mononuclear cell infiltration and Gram-positive small bacilli. The organisms were also present in the foci of mononuclear cells at the central gray matter of the mesencephalon. Listeria monocytogenes was isolated from the brain and other organs of the whole body.

Animals↗
PubMed1992

Clinicopathology of meningoventriculitis due to Streptococcus bovis infection in neonatal calves.

Three neonatal calves ranging in age from 4 to 14 days were examined pathologically and bacteriologically. The calves showed depression, anorexia, pyrexia, and difficulty or inability to stand followed by cloudiness of the ocular aqueous humor or cornea. Autopsy revealed congestion, petechiae, and cloudy areas in the meninges. Histologically, the central nervous system (CNS) lesions were prominent and limited to the meninges where fibrinous exudate and infiltrations of neutrophils, macrophages, and lymphocytes were present. There were mild or slight degrees of choroid plexitis and ependymitis. Endophthalmitis was seen as a concurrent lesion in all cases. Fibrinous or fibrinopurulent changes were found in the peritoneum and epicardium as well as in several other organs. Numerous Gram-positive cocci were detected in affected areas of the whole body. Bacteriologically, Streptococcus bovis was isolated from all examined materials consisting of the brain, cerebrospinal fluid, ocular aqueous humor, and several other organs. These results suggest that the lesions were associated with infection of the organism and that the present cases were in the process of septicemia.

Animals↗