Biomedical subjects

H Takeda

Publications and source records attributed to H Takeda.

At least 415 records · Page 23Linked to original sources

PubMed1993

Real-time cardiac output estimation of the circulatory system under left ventricular assistance.

A new method for indirect and real-time estimation of the cardiac output of the circulatory system supported by the left ventricular assist device (LVAD) was proposed. This method has low invasiveness and is useful for clinical application of the LVAD since it needs only two measurements: the outflow rate of blood from the LVAD and the aortic pressure. The proposed method is based on a system identification technique for the time series model of the cardiovascular system and requires less computational time than other methods with similar estimation accuracy. Hence, the proposed method could be implemented in a personal computer system and realize the on-line and real-time estimation of the instantaneous outflow rate of the natural heart. The efficiency and limitation of the method were discussed on the basis of the results obtained from in vitro experiment using a mock circulatory system and in vivo experiment using an adult goat. It was revealed that the method could obtain a fairly high correlation coefficient between the true stroke volume of the natural heart and its estimate of more than 0.99 (in vivo) or 0.95 (in vivo). This means that there is a fair possibility of applying the proposed estimation system to the clinical use.

Animals↗

PubMed1993

Effects of sumatriptan on the cerebral intraparenchymal microcirculation in the cat.

1. Sumatriptan, a 5-hydroxytryptamine (5-HT)1-like receptor agonist, is effective against the headache of migraine. The effects of sumatriptan injected via the carotid artery on the cerebral microcirculation were studied in 10 anaesthetized cats. 2. The local cerebral blood volume (CBV), mean transit time of blood (MTT) and cerebral blood flow (CBF) in the parieto-temporal cortex were measured by a photoelectric method. CBV represents the cumulative dimensions of the cerebral microvessels. 3. Sumatriptan at 5 and 50 micrograms kg-1 had no significant effects on the CBV, MTT, CBF, and mean arterial blood pressure (MABP); 500 micrograms kg-1 of sumatriptan reduced the CBV, prolonged the MTT, and decreased the CBF (approximately -20%) without affecting the MABP. Sumatriptan, 5 mg kg-1, elicited transient reductions in CBV and CBF, which were attributable to the rapid and marked falls of MABP seen with this dose. 4. Thus, while a high dose of sumatriptan (500 micrograms kg-1) exhibits direct vasoconstrictor actions on the cerebral vessels, low doses of sumatriptan, within the therapeutic range, elicit no vasoconstriction. The data do not support a vasoconstrictor action of sumatriptan playing a primary role in reversing the headache of migraine.

Animals↗

PubMed1993

Exercise-induced upward shift of diastolic left ventricular pressure-volume relation in patients with dilated cardiomyopathy. Effects of beta-adrenoceptor blockade.

BACKGROUND: The effectiveness of beta-blocker therapy for dilated cardiomyopathy (DCM) may be attributed to the inhibition of detrimental effects on the failing heart of sympathetic stimulation during exertion. However, the harmful effects of activity as well as the protective effects of beta-blockers have not been demonstrated. Diastolic ventricular function is known to be sensitive to transient myocardial metabolic insult. In this study, we investigated the effect of modest exercise with or without beta-blockade on the diastolic left ventricular pressure-volume (P-V) relation in patients with DCM. METHODS AND RESULTS: The diastolic left ventricular P-V relation was obtained by high-fidelity pressure measurements and digital subtraction left ventriculography at rest and immediately after modest supine bicycle exercise in 12 patients with DCM. The effects of intravenous administration of 0.1 mg/kg propranolol on resting and exercise P-V relations were studied. The end-diastolic and lowest left ventricular pressures were significantly elevated by exercise (20 +/- 9 to 32 +/- 13 mm Hg, P < .01, and 12 +/- 6 to 21 +/- 11 mm Hg, P < .01, respectively) despite insignificant changes in left ventricular volumes. The administration of propranolol did not alter the resting diastolic P-V relation. However, propranolol significantly attenuated the exercise-induced upward shift of the diastolic P-V relation despite a significant increase in end-diastolic volume. The significant upward shift and attenuation by propranolol were also observed even when the left ventricular pressure was corrected by the subtraction of right atrial pressure. CONCLUSIONS: These results indicate that even modest exercise exerts detrimental effects on diastolic left ventricular function of the failing heart through beta-adrenergic stimulation. The clinical effectiveness of beta-blocker therapy in patients with DCM can be attributed in part to the inhibition of detrimental myocardial effects of sympathetic stimulation during daily activity.

Adrenergic beta-Antagonists↗

PubMed1993

Ticlopidine improves the enhanced erythrocyte aggregability in patients with cerebral infarction.

BACKGROUND AND PURPOSE: We examined the effect of ticlopidine hydrochloride on the enhanced erythrocyte aggregability in 14 patients with cerebral infarction during the chronic phase (over 1 month after onset). SUMMARY OF REPORT: Ticlopidine (100 mg BID) was administered for 8 weeks. We measured the rate of erythrocyte aggregation (aggregability), using the whole-blood erythrocyte aggregometer that we developed, before and at 4 and 8 weeks after the initiation of ticlopidine administration. Concomitant measurements were made of such blood factors as the hematocrit, albumin-globulin ratio, and fibrinogen concentration. The erythrocyte aggregation rates before and at 4 and 8 weeks after were 0.147 +/- 0.017/s, 0.138 +/- 0.019/s, and 0.133 +/- 0.017/s, respectively. The erythrocyte aggregation rates at 4 and 8 weeks were significantly lower (P < .05 by Bonferroni's modified t test) than those before ticlopidine administration. At 4 and 8 weeks after the initiation of ticlopidine treatment, the hematocrit value and concentration of fibrinogen were also significantly (P < .05) reduced. CONCLUSIONS: Our results suggest that ticlopidine can improve the enhanced erythrocyte aggregability in patients with cerebral infarction during the chronic phase.

Adult↗

PubMed1993

[The role of the central monoaminergic nervous system relative to mechanisms of stress adaptation].

The difference of amine dynamics in central noradrenergic, dopaminergic and serotonergic systems of adaptive or non-adaptive rats to repeated restraint stress was investigated neurochemically. A single immobilization induced stress responses, such as reductions in growth rate, food intake, water intake and locomotor activity, and an increase in pain threshold. These responses disappeared after repeated immobilization 1 or 2 hr daily for 7 days, but not after 4 hr daily for 7 days. These results suggest that stress adaptation models should include the parameter of repeated exposure to restraint stress 1 or 2 hr daily for 7 days. In the frontal cortex, midbrain-thalamus, striatum, hypothalamus, medulla-pons, cerebellum, cervical cord, thoracic cord and lumbar cord of models with adaptability to repeated restraint stress, a marked increase in serotonin (5-HT) turnover was observed. This neurochemical change was seen in the hypothalamus and lumbar cord of non-adaptive models, but not in the other brain and spinal cord regions. Also, an increase in norepinephrine (NE) turnover in spinal cord regions was observed in adaptive models, but NE turnover was decreased in the frontal cortex, striatum or cervical cord of non-adaptive models. These findings suggest that enhancement of central 5-HT turnover and NE turnover in the spinal cord contribute to the formation of adaptation to repeated restraint stress.

Adaptation, Physiological↗

PubMed1993

[A case of bronchogenic squamous cell carcinoma associated with Swyer-James syndrome].

Swyer-James syndrome is considered to be a relatively uncommon disease entity presenting with unilateral hyperlucent lung due to hypoplasia of a pulmonary artery and bronchiectasis of the affected lung. Association of bronchogenic carcinoma with Swyer-James syndrome has not apparently been reported in any previous literature, except for one Japanese case. In the present paper, we describe a 48-year-old male individual, who developed poorly differentiated squamous cell carcinoma of the right upper lobe bronchus after he had been diagnosed to have Swyer-James syndrome with unilateral hyperradiancy of the left lung. It is suggested that the bronchial epithelium of the unaffected lung in Swyer-James syndrome is likely to be more exposed to extrinsic carcinogens than that of the affected, underventilated lung, hence resulting in a higher risk of developing bronchogenic carcinoma.

Carcinoma, Squamous Cell↗

PubMed1993

[Usefulness of myocardial imaging by 123I-MIBG in assessment of diabetic neuropathy].

In diabetic patients with autonomic neuropathy, it is suggested that there is a reduced uptake of 123I-MIBG in the heart. We compared the difference of myocardial 123I-MIBG accumulation between 4 diabetic patients with triopathy and 6 patients without it. In all 10 patients, coronary angiography and 201Tl imaging (rest and 4 hours later) were performed. 123I-MIBG (111 MBq) was administered intravenously and its imaging was recorded on 15 minutes and 4 hours after injection. In all 4 cases with triopathy, 123I-MIBG imaging showed defect in apical and inferior region. In 2 out of 6 cases without triopathy, rapid clearance was noticed in apical and inferior region. There was no significant stenosis in right coronary artery and no defect in initial and delayed 201Tl images in all cases. We concluded that diabetic autonomic neuropathy in the heart was prominent in apical and inferior region and 123I-MIBG imaging might be useful for the evaluation of degrees in diabetic neuropathy.

3-Iodobenzylguanidine↗

PubMed1992

A POU-domain gene of zebrafish, ZFPOU1, specifically expressed in the developing neural tissues.

We have isolated a POU domain-containing cDNA (ZFPOU1) from a cDNA library of zebrafish (Brachydanio rerio). The ZFPOU1 cDNA contained an open reading frame encoding a 425 amino acid peptide. The conserved POU domain was located near the carboxy terminus. The deduced amino acid sequence of the reading frame was most similar to that of the mouse class III POU-domain gene, Brain-1. Northern blot analysis revealed that the ZFPOU1 transcripts first appeared at the early neurula stage of embryogenesis and transiently increased thereafter. A significant level of expression, however, was not found in adult tissues except in the brain. In situ hybridization analysis demonstrated that the ZFPOU1 transcripts were localized in the neural tissues of embryos, but not in mesodermal, endodermal or ectodermal tissues. In adult zebrafish, the ZFPOU1 transcripts were detected in the restricted regions of the brain. Spatial and temporal expression patterns suggest that ZFPOU1 has distinct roles in the early neural development of zebrafish.

Amino Acid Sequence↗

PubMed1992

An immunohistochemical study with an estrogen receptor-related protein (ER-D5) in human colorectal cancer.

The ER-D5 antigen is a protein associated with the estrogen receptor that is present only in estrogen receptor-positive tissues. To clarify the estrogen receptor in colon cancer, the localization of ER-D5 was studied immunohistochemically. Forty-three of 171 (25.1%) specimens of colon cancer showed reactivity for ER-D5. Reactivity was seen only in the cytoplasm. No reactivity was seen in cancer limited to the mucosa or in adenoma, but submucosal cancers showed a rate of positivity similar to cancers that involved lamina muscularis and beyond. Estradiol staining was done on serial sections from 56 specimens. There was a significant relationship between reactivity for estradiol and that for ER-D5. In the 15 specimens where both ER-D5 and estradiol were positive, the distribution of estradiol was similar to that of ER-D5. It was concluded that the immunohistochemical localization of ER-D5 indirectly shows that of the estrogen receptor in colorectal cancer tissues.

Adenocarcinoma↗

PubMed1992

[Reevaluation of US and CT findings in adult intussusception].

Computed tomographic (CT) and ultrasonographic (US) findings of 10 adult patients with 11 intussusceptions were retrospectively analyzed. Through close scrutiny of wall structures of intussusceptums and mesenteric fat, new features of adult intussusceptions were found: 1. The returning walls were thicker than the entering walls in 10 of 11 intussusceptums. 2. The neck of the returning wall was thicker than its head in eight of nine intussusceptums. 3. Longitudinal compression of the wall and venous congestion resulting from an inside out turning of the wall structure were thought to be the cause of thickening of the returning wall. 4. Invaginated mesenteric fat tended to be located at the head (apex) in two of seven intussusceptions, making differentiation from intussusception caused by lipoma difficult. 5. The leading masses were detectable as apical soft tissue density masses in eight of 10 intussusceptions. These findings contradict those of previous reports on adult intussusceptions.

Adult↗

PubMed1992

Relationship of Helicobacter pylori to serum pepsinogens in an asymptomatic Japanese population.

A seroepidemiologic study of the prevalence of Helicobacter pylori infection in Japan was performed, and the relationship between serum pepsinogen I and II levels (markers of gastritis and gastric atrophy) and H. pylori infection was investigated. Four hundred and eighteen asymptomatic children and adults were studied. The prevalence of anti-H. pylori immunoglobulin G antibody increased with age. For persons born after 1950, the frequency of H. pylori infection increased at approximately 1% per year; for those born before 1950 the prevalence was high (70%-80%) and relatively constant. Serum pepsinogen I and II levels were significantly higher in H. pylori-infected volunteers than in H. pylori-uninfected volunteers [51.6 +/- 3 vs. 42.9 +/- 2 ng/mL (P less than 0.05) for pepsinogen I; 16.0 +/- 1 vs. 7.5 +/- 0.8 ng/mL (P less than 0.001) for pepsinogen II]. The ratio of pepsinogen I to pepsinogen II was significantly lower in H. pylori-infected volunteers (3.5 +/- 0.2) than in uninfected volunteers (6.3 +/- 0.3; P less than 0.001). The apparent decrease in prevalence of H. pylori accompanying the Westernization of Japan may eventually be accompanied by a reduction in the frequency of atrophic gastritis, the precursor lesion of the epidemic form of gastric carcinoma, and ultimately result in a decrease in the incidence of gastric carcinoma in Japan.

Adolescent↗

PubMed1992

Cerebral microcirculatory changes during and following transient ventricular tachycardia in cats.

Although reduced cerebral perfusion is believed to be the cause of syncope due to cardiac arrhythmias, investigations on the cerebral microcirculation during cardiac arrhythmias have been rare. We therefore studied the effects of transient ventricular tachycardia on the local cerebral blood volume and blood flow. Experimental ventricular tachycardia was induced in cats by electrically stimulating the ventricle of the heart at a rate of 300/min for 1 min. Using our photoelectric method, the local cerebral blood volume, mean transit time of blood, and cerebral blood flow in the parieto-temporal region were measured during and for 3 h after ventricular tachycardia. Transient ventricular tachycardia of as short as 1 min caused cerebral ischemia with a blood flow reduction of approximately 30%. This was considered to be due to reduced blood pressure plus transient autonomic dysfunction, or dysautoregulation, during the ventricular tachycardia. Mild and transient reactive hyperemia occurred immediately after termination of the dysrhythmia, but continuous reductions of cerebral blood flow were observed thereafter for 3 h. This delayed hypoperfusion is attributable to either vasoconstriction of the large resistance vessels or changes in the hemorheological properties of the blood caused by cerebral ischemia. Ventricular tachycardia of the type reported has significant and long-lasting effects on the cerebral microcirculation.

Animals↗

PubMed1992

Alpha-oxidation of fatty acids in fasted or diabetic rats.

Induction of alpha-oxidation, a possible gluconeogenic process, which should produce odd-chain fatty acids from even-chain fatty acids, was studied in rats fasted or made diabetic with streptozotocin. When a omega-phenylated even-chain fatty acid, phenylbutyric acid (1.2 mmol/kg), was administered to rats under these conditions, a significant increase in the urinary excretion of benzoic acid, the metabolic end-product of omega-phenylated odd-chain fatty acids, was observed in fasted (3.54 +/- 0.46 mumol/day) and diabetic (6.73 +/- 2.10) rats (control, 0.58 +/- 0.43; P less than 0.001). Phenylated longer chain fatty acids, phenylhexanoic and phenyldecanoic acid, did not produce significantly more benzoic acid than did phenylbutyric acid. Although the rate of alpha-oxidation was very low compared to that of beta-oxidation, these results suggested that alpha-oxidation of fatty acids was induced under fasting or diabetic conditions, and that alpha-oxidation might take place at the butyric acid stage.

Animals↗

PubMed1992

Nuclear localization of androgen receptor in heterogeneous samples of normal, hyperplastic and neoplastic human prostate.

To facilitate an understanding of how androgens participate in the genesis of human benign hyperplasia and carcinoma we assayed androgen receptor in the epithelium and stroma of human prostatic tissue from 57 patients. Immunohistochemical staining of human androgen receptor was performed on 106 sections of normal prostate, benign prostatic hyperplasia (BPH) and prostate cancer. To determine variability of androgen receptor staining sections taken from different portions of the gland were studied. Frozen tissue sections were incubated with monoclonal antiandrogen receptor antibodies and staining was completed by the indirect avidin-biotin peroxidase method. Antibody staining was found mainly in the nucleus of prostatic epithelial cells, although some stromal cells also showed positive staining. Unlike normal prostate, there was a heterogeneous distribution of androgen receptor in BPH and prostate cancer. The androgen receptor content in well differentiated adenocarcinoma epithelium was significantly higher compared to moderately (p less than 0.05) and poorly (p less than 0.05) differentiated adenocarcinoma. Regardless of the origin of stromal tissue, some staining was observed. In each specimen studied the androgen receptor staining was consistent qualitatively and quantitatively for each pathological component throughout the specimen. These data confirm that androgen receptor is a nuclear receptor protein. Furthermore, they show the ability of monoclonal antibodies to reveal cellular/subcellular distribution of androgen receptor, and demonstrate a correlation between the degree of tumor differentiation and androgen receptor content in epithelial but not in stromal cells. These observations may have important implications for understanding the variable tumor response to hormone therapy.

Adenocarcinoma↗

PubMed1992

Stress-induced gastric mucosal lesion and platelet aggregation in rats.

The effect of cold-restraint stress on platelet function in vitro was studied in the rat model. Platelet function was assessed by platelet aggregation in response to adenosine diphosphate (ADP) and thrombin. ADP-induced platelet aggregation was reduced in platelet-rich plasma after 2 h of cold-restraint stress. Thrombin-induced platelet aggregation was reduced with time during cold-restraint stress with a parallel increase in the lesion index. Although pretreatment of animals with atropine prevented the development of gastric mucosal lesions, platelet dysfunction was not reversed by this treatment. These results suggest that cold-restraint stress may impair platelet function, probably due to platelet activation in vivo, and that the abnormalities in platelet function may be associated with the development of gastric mucosal lesions.

Adenosine Diphosphate↗

PubMed1992

An automatic control algorithm for the optimal driving of the ventricular-assist device.

This paper presents a new method of keeping one of the most suitable driving conditions for regulating the outflow volume from the ventricular-assist device (VAD). The experimental results from a mock circulatory system have shown that the relationship between the stroke volume and the systolic duration of the VAD can be specified by the combination of characteristic curves of the positive and negative drive pressures. The optimal operating point on the characteristic curve have been defined as the point at which thrombosis on the blood-contacting surface and hemolysis due to mechanical damage can be avoided and at which the driving energy can be minimized. The present analysis has been revealed that the optimal operating point is the vertex of the triangular figure obtained from the characteristic curve. The algorithms for keeping the optimal operating point and for regulating the stroke volume have been also proposed.

Algorithms↗

PubMed1992

Expression of c-kit, a proto-oncogene of the murine W locus, in cerebella of normal and neurological mutant mice: immunohistochemical and in situ hybridization analysis.

The c-kit proto-oncogene encodes a receptor tyrosine kinase and is allelic with the murine white-spoting (W) locus. Although no apparent defects in the brain have been reported in W mutant mice, brain tissue, especially cerebellum, shows a high level of c-kit transcription. In the present study, sites of c-kit expression in the cerebellum were exained by immunohistochemical and in situ hybridization techniques. Immunohistochemistry with a monoclonal antibody against c-Kit protein revealed that the c-Kit protein was localized close to the Purkinje cell soma in the region facing the granular cell layer. Similar distribution of the c-Kit protein was observed in cerebella of mutant mice in which the Purkinje cell (pcd) or the granular cell layer (weaver) is missing. These data suggest that the c-Kit protein is produced not by the Purkinje cell nor by the granular cell but by the cells present in the molecular layer and that the protein is then transported to the region around the Purkinje cell soma. This interpretation was supported by in situ hybridization analysis: cells containing the c-kit transcripts were found only in the molecular layer, while the granular and Purkinje cells were negative.

Alleles↗

PubMed1992

[A study to clarify the mechanism of the usefulness of the macrolides--the influence of clarithromycin to biofilm with P. aeruginosa].

Clarithromycin (CAM) was administered long-term to patients with diffuse panbronchiolitis (DPB) to clarify the mechanism of the usefulness of the macrolides (MLs). 1. A tendency for clinical improvement was observed in 17 patients with DPB. Bacteria were eradicated in 7 of 9 patients with P. aeruginosa found in sputum. 2. A biofilm experimental model with P. aeruginosa was found to be destructed through constant contact with CAM and formed into a single cell with a smooth surface. 3. It was believed that the new lesion forming capability of P. aeruginosa that had been in contact with CAM was reduced due to a significant decrease in adherence to tissue. P. aeruginosa was principally eradicated by the host factors. These results suggested that the improvement in the prognosis of DPB with P. aeruginosa in the sputum after adding MLs was closely related to the destructive effect of the MLs on the biofilm.

Animals↗