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Biomedical subjects

Kenichi Ogawa

Publications and source records attributed to Kenichi Ogawa.

At least 19 recordsLinked to original sources
PubMed2007

Honda humanoid robots development.

Honda has been doing research on robotics since 1986 with a focus upon bipedal walking technology. The research started with straight and static walking of the first prototype two-legged robot. Now, the continuous transition from walking in a straight line to making a turn has been achieved with the latest humanoid robot ASIMO. ASIMO is the most advanced robot of Honda so far in the mechanism and the control system. ASIMO's configuration allows it to operate freely in the human living space. It could be of practical help to humans with its ability of five-finger arms as well as its walking function. The target of further development of ASIMO is to develop a robot to improve life in human society. Much development work will be continued both mechanically and electronically, staying true to Honda's 'challenging spirit'.

Artificial Intelligence↗
PubMed2006

Uncoupling protein 2 promoter polymorphism -866G/A affects peripheral nerve dysfunction in Japanese type 2 diabetic patients.

OBJECTIVE: To determine genetic predispositions for diabetic polyneuropathy, we investigated the relationship between the -866G/A polymorphism of uncoupling protein (UCP) 2 and neurological manifestations in 197 type 2 diabetic patients. RESEARCH DESIGN AND METHODS: We first examined whether UCP2 mRNA had been expressed in the dorsal root ganglion (DRG) in four Long-Evans Tokushima Otsuka rats using RT-PCR and electrophoresis. Genotyping of UCP2 promoter polymorphism -866G/A was then performed in 197 unrelated Japanese type 2 diabetic patients, who were subjected to nerve conduction, quantitative vibratory perception, head-up tilt, and heart rate variability tests, by PCR restriction fragment-length polymorphism. The relationships between UCP2 genotype and various nerve functions were analyzed by uni- and multivariable analysis. RESULTS: Expression of UCP2 mRNA was confirmed in rat DRG. Multiple regression analysis clarified the hypothesis that the G/A + A/A genotype was significantly related to decreased motor nerve conduction velocity and impaired blood pressure maintenance on the head-up tilt test. Multiple logistic regression analysis revealed that the G/A + A/A genotypes are a significant risk factor for sensory nerve conduction slowing and orthostatic hypotension. CONCLUSIONS: UCP2 promoter gene polymorphism -866 G/A was significantly associated with nerve conduction slowing and vasomotor sympathetic functions. These findings suggest that the higher UCP2 activity related to the A allele has an energy-depleting effect on peripheral nerve function in type 2 diabetic patients.

Alleles↗
PubMed2005

Effect of benzodiazepine hypnotic triazolam on relationship of blood pressure and Paco2 to cerebral blood flow during human non-rapid eye movement sleep.

We sought to clarify the effect of short-acting benzodiazepine hypnotic on the relationship of arterial blood pressure and arterial partial pressure of carbon dioxide (Paco2) to regional cerebral blood flow (rCBF) during human non-rapid-eye-movement (non-REM) sleep. Nine young normal volunteers were treated in a randomized, crossover design with triazolam or placebo and underwent positron emission tomography at night. During wakefulness and stage 2 and slow wave (stages 3 and 4) sleep, we measured mean arterial blood pressure (MAP), Paco2, and absolute CBF. With triazolam compared to placebo, MAP reduced gradually. During stage 2 sleep, Paco2 increased and whole-brain mean CBF decreased. With triazolam, relative rCBF of the left orbital basal forebrain decreased more during stage 2 than slow wave sleep, whereas absolute CBF of the occipital cortex and cerebral white matter remained constant. During triazolam-induced stage 2 sleep, absolute CBF of the cerebral white matter correlated more strongly to both MAP and Paco2 than during placebo sleep and also correlated more strongly to both MAP and Paco2 than absolute CBF of the occipital cortex. In the frontal white matter, during triazolam-induced stage 2 sleep compared to wakefulness, absolute CBF was significantly better correlated to MAP, but not to Paco2. During triazolam-induced stage 2, the cerebral white matter may receive a modulated CBF regulation having the strengthened relationship of Paco2 to CBF and, more locally, the frontal white matter may depend precariously on CBF regulation.

Adult↗
PubMed2005

Peripheral nerve functions may deteriorate parallel to the progression of microangiopathy in diabetic patients.

Our aim was to obtain information to help in the early detection of impaired nerve function and to assess the severity of diabetic symmetric polyneuropathy (DPN). Various somatic and autonomic nerve functions in 40 diabetics and 20 age-matched healthy volunteers were evaluated using six objective examinations: nerve conduction study, quantitative vibratory perception threshold, heart rate variability, Valsalva test, head-up tilt and quantitative sudomotor axonal reflex test (QSART). The diabetics were divided into three groups according to the severity of their microangiopathy. The nerve function data and level of impairment were compared between a healthy control and three diabetic groups. The relationships between nerve function data and clinical background were also examined using multivariate analysis. Results were as follows: (1) all nerve dysfunctions seemed to develop parallel to the progression of microangiopathy, (2) reduced nerve conduction velocity and elevated vibratory perception thresholds in the feet might be early detectable signs of DPN, (3) vasomotor and sudomotor sympathetic functions and cardiovagal functions seemed to deteriorate with the appearance of microangiopathy, (4) lowered compound muscle action potential seemed to appear at the advanced microangiopathic condition, (5) hypohydrosis was closely related to diabetic foot ulcers. In conclusion, nerve dysfunction in diabetics might generally progress with microangiopathy from somatic sensory nerve dysfunction to autonomic nerve dysfunction and then to somatic motor nerve dysfunction. Sympathetic sudomotor dysfunction might be a sensitive predictor of diabetic foot ulcer.

Adult↗
PubMed2005

Prevalence and risk factors for erectile dysfunction in Japanese diabetics.

We evaluated the prevalence and risk factors for erectile dysfunction (ED) and interest in ED treatment among Japanese men being treated for type 2 diabetes mellitus. Patients (40-79 years; n=1118) completed the 5-item version of the International Index of Erectile Function (IIEF-5), and questions related to interest in ED pharmacotherapy, subjective symptoms of diabetes, and general quality of life. A separate survey completed by physicians examined the relationships between age, diabetic treatments (insulin or oral), symptoms of diabetes (poor glycemic control, microangiopathy), complications of diabetes (hypertension, ischemic heart disease, cerebrovascular disease), and ED. The prevalence of ED in patients with diabetes was 90%, a rate double that of non-diabetic individuals. Multivariate analyses revealed that age, insulin therapy, microangiopathy, hypertension, history of cerebrovascular or cardiovascular disease, leg dysesthesia, dysuria, insomnia, and anorexia all represented significant risk factors for ED. Half of all respondents were interested (29%) or would consider pharmacotherapy for ED (21%). These findings suggest that ED is a significant problem in Japanese men with diabetes, and that specific risk factors increase the prevalence of ED. Furthermore, the survey results expose national attitudes toward treatment of ED.

Adult↗
PubMed2005

Increased gene expression of antioxidant enzymes in KKAy diabetic mice but not in STZ diabetic mice.

Oxidative stress and the gene expression at the transcriptional level of antioxidant enzymes were investigated in two models of diabetes in mice. We used KKAy mice as a model of obese insulin-resistant diabetes, and streptozotocin-induced diabetic mice (STZ mice) as a model of insulin-deficient diabetes. C57BL mice and saline-injected ICR mice were used as the respective non-diabetic controls. To assess oxidative damage, plasma malonedialdehyde (MDA), urine 8-isoprostane and 8-hydroxy deoxyguanosine (8-OHdG) were measured. The mRNA expression of antioxidant enzymes, superoxide dismutase 1 (SOD-1) and glutathione peroxidase 1 (GPx-1) in the kidney and heart were quantified using a real-time polymerase chain reaction. The KKAy mice demonstrated moderate hyperglycemia and hyperlipidemia, and the STZ mice showed severe hyperglycemia and hypolipidemia. The KKAy mice, but not the STZ mice, showed elevated plasma MDA relative to the non-diabetic controls. Urine 8-isoprostane and 8-OHdG in both diabetic mouse groups increased significantly. The urine oxidative stress markers in the severely hyperglycemic STZ mice were higher than those in the moderately hyperglycemic KKAy mice. Although GPx-1 and SOD-1 showed elevated mRNA expression in the KKAy mice in the kidney and heart, in the STZ mice they did not increase compared to the controls. The compensatory up-regulation of the mRNA expression of antioxidant enzymes may be impaired in the insulin-deficient severely hyperglycemic state.

Animals↗
PubMed2005

Comparison of the effects of a distal embolic protection device and an aspiration catheter during percutaneous coronary intervention in patients with acute myocardial infarction.

BACKGROUND: The beneficial effect of percutaneous coronary intervention (PCI) using stents for acute myocardial infarction (AMI) has already been demonstrated, but there is the problem that mechanical microvascular occlusion can occur because of thrombus/atheroma embolization when the PCI was performed. The aim of the present study was to retrospectively test and compare the effects of an aspiration catheter or distal embolic protection with a distal occlusion balloon catheter to prevent peripheral vascular embolization. METHODS AND RESULTS: The subjects consisted of 135 patients who underwent PCI with stenting within 12 h of the onset of chest pain caused by their first AMI. They were divided into 2 groups; the aspiration group, consisted of 81 consecutively seen patients who underwent aspiration catheter treatment between January 2001 and May 2002, and the distal protection group was the next group of 54 consecutively seen patients treated with a distal protection device between June 2002 and February 2003. The results were as follows. Thrombolysis in Myocardial Infarction (TIMI) score of 3 was obtained significantly more frequently in the distal protection group (94.4%) than in the aspiration group (79.0%). Additionally, the intensity of the cardiac muscle stain (blush score) was evaluated on coronary angiography and the rate of cases showing a blush score of 3, which indicates favorable blood perfusion at the tissue level, in the distal protection group (56.6%) was significantly greater than in the aspiration group (33.3%, p<0.01). The time to peak blood concentration of creatinine kinase was also significantly shorter in the distal protection group. CONCLUSIONS: The distal embolism protection method is superior to the aspiration method for prevention of embolization after PCI with stenting for AMI, in terms of tissue level reperfusion in myocardial recanalization therapy.

Cardiac Catheterization↗
PubMed2004

Cerebral white matter blood flow is constant during human non-rapid eye movement sleep: a positron emission tomographic study.

This study aimed to identify brain regions with the least decreased cerebral blood flow (CBF) and their relationship to physiological parameters during human non-rapid eye movement (NREM) sleep. Using [(15)O]H(2)O positron emission tomography, CBF was measured for nine normal young adults during nighttime. As NREM sleep progressed, mean arterial blood pressure and whole brain mean CBF decreased significantly; arterial partial pressure of CO(2) and, selectively, relative CBF of the cerebral white matter increased significantly. Absolute CBF remained constant in the cerebral white matter, registering 25.9 +/- 3.8 during wakefulness, 25.8 +/- 3.3 during light NREM sleep, and 26.9 +/- 3.0 (ml.100 g(-1).min(-1)) during deep NREM sleep (P = 0.592), and in the occipital cortex (P = 0.611). The regression slope of the absolute CBF significantly differed with respect to arterial partial pressure of CO(2) between the cerebral white matter (slope 0.054, R = - 0.04) and frontoparietal association cortex (slope - 0.776, R = - 0.31) (P = 0.005) or thalamus (slope - 1.933, R = - 0.47) (P = 0.004) and between the occipital cortex (slope 0.084, R = 0.06) and frontoparietal association cortex (P = 0.021) or thalamus (P < 0.001), and, with respect to mean arterial blood pressure, between the cerebral white matter (slope - 0.067, R = - 0.10) and thalamus (slope 0.637, R = 0.31) (P = 0.044). The cerebral white matter CBF keeps constant during NREM sleep as well as the occipital cortical CBF, and may be specifically regulated by both CO(2) vasoreactivity and pressure autoregulation.

Adult↗
PubMed2004

Prevalence and risk factors of erectile dysfunction in Japanese men with type 2 diabetes.

This study aimed to elucidate the prevalence and clinical risk factors of erectile dysfunction (ED) in Japanese male diabetics. Questionnaires were administered to 82 male diabetics and 25 male non-diabetics (controls), to determine the international index of erectile function (IIEF). This index consists of five parts, with questions related to erectile function (EF), intercourse satisfaction (IS), orgasmic function (OF), sexual desire (SD), and overall satisfaction (OS). IIEF scores were compared between diabetics and controls, and were also analyzed in relation to clinical factors. Although EF, IS, and OF scores (physical factors) in diabetic men were significantly lower than those of age-matched controls, no significant differences were apparent in SD and OS scores (psychological factors). All patients with EF score > or = 18 reported being able to achieve sexual intercourse, we determined the criterion for ED as EF < 18. The prevalence of ED in diabetics and age-matched controls was 60% and 20%, respectively. EF score decreased with duration of diabetes and progression of retinopathy, proteinuria, ischemic heart disease, delayed nerve conduction, orthostatic intolerance, and attenuated heart rate variability. ED was found to be common in Japanese male diabetics. Possible influences of both microangiopathy and macroangiopathy on ED are suggested.

Diabetes Mellitus, Type 2↗
PubMed2004

Deactivation by benzodiazepine of the basal forebrain and amygdala in normal humans during sleep: a placebo-controlled [15O]H2O PET study.

OBJECTIVE: The authors' goal was to identify differences in regional brain activity between physiological and benzodiazepine-induced sleep to clarify the brain structures involved in the drug's hypnotic effect. METHOD: Using positron emission tomography, they compared regional cerebral blood flow during non-REM sleep in nine volunteers treated with placebo or triazolam, a short-acting benzodiazepine, in a double-blind, crossover design. RESULTS: Blood flow in the basal forebrain and amygdaloid complexes was lower during non-REM sleep when subjects were given triazolam than when they were given placebo. CONCLUSIONS: The hypnotic effect of the benzodiazepines may be mediated mainly by deactivation of the forebrain control system for wakefulness and also by the anxiolytic effect induced by deactivation of the emotional center.

Adult↗
PubMed2004

Effects of enhanced external counterpulsation on hemodynamics and its mechanism.

BACKGROUND: The hemodynamic effects of enhanced external counterpulsation (EECP) and its mechanism(s) were investigated in relation to neurohumoral factors in patients with acute myocardial infarction (AMI). METHODS AND RESULTS: Twenty-four patients with AMI were studied before, during and after EECP treatment for 60 min. Heart rate (HR), right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were determined. In addition, circulating concentrations of neurohumoral factors were determined at each time point. HR did not change following EECP treatment. However, RAP and PCWP increased significantly and CI was significantly elevated during EECP and thereafter. Blood atrial natriuretic peptide (ANP) concentration was significantly increased 15 and 60 min after the start of EECP treatment, but brain natriuretic peptide (BNP) did not change. Renin, aldosterone and catecholamine concentrations also did not change. CONCLUSION: Treatment with EECP resulted in an increased preload because of increased venous return, and CI was increased thereafter. In patients with AMI, EECP increased blood ANP concentration, but not BNP, which suggests that an increase in ANP without an increase in BNP is an important mechanism for the effects of EECP treatment.

Aged↗
PubMed2004

[Development of automatic verification system for portal image in radiotherapy].

The current method of verification for external beam radiation therapy visually compares a simulation image with a portal image. However, because this method depends largely upon the observer's experience, it sometimes results in inter-observer differences. In this study, we developed software to measure atomatically the quantitative difference between the simulation image and portal image using an image-analysis method. The feasibility of this software was evaluated on a rectangular field in the pelvic region. We took 12 simulation images of a pelvic phantom, setting 4 different field shapes on each of 3 isocenters. We then obtained 84 portal images setting 7 known distances from each of the 12 simulation images. Using this software, the direction of shift was detected correctly, and the distance of shift was detected correctly to within less than 3 mm. We consider that this software could be a useful method of verification.

Computer Simulation↗
PubMed2004

[Evaluation of radiation therapy for keloid using electron beam].

In radiation therapy for keloid, electron beams are delivered to the skin through a lead shield hollowed into the shape of the keloid. The shape of a postoperative keloid scar is linear, causing the irradiation shield to be long and narrow. This lead shield is put on the surface of the skin. Therefore, it is considered that beam data used in general external irradiation are not applicable to irradiation for keloid. Therefore, we used a water equivalent phantom and measured beam data by using chambers or film dosimeters. Experimental conditions were the same as those of actual radiotherapy for keloid. As a result of this procedure, the radiation technique was optimized. Electron energy and thickness of the bolus, thickness of the lead shield, margins such that the planning target volume would receive the necessary dose, and the method of MU calculation all were determined. It was suggested that these experiments were useful to establish the appropriate technique in irradiation for keloid.

Electrons↗
PubMed2003

Spectral analyses of electroencephalography and heart rate variability during sleep in normal subjects.

We investigated the relationship between electroencephalogram (EEG) activity and autonomic nervous system function using spectral analyses of EEG and heart rate variability (HRV) in healthy subjects during sleep. Eleven subjects were enrolled in this study. From EEG, the spectral edge frequencies (SEFs including SEF50, SEF90 and SEF95) were calculated. From electrocardiogram (ECG), the spectral powers of low-frequency band (LF: 0.04-0.15 Hz), high-frequency band (HF: 0.15-0.4 Hz) and the ratio of LF to HF (LF/HF) were calculated. During sleep, each set of data was obtained as the average of a 5-min measurement. We found that SEFs and LF/HF or LF decreased simultaneously and periodically, suggesting simultaneous depression of EEG activity and relative sympathetic activity, and SEFs significantly correlated with LF/HF and LF in all subjects during sleep, but not with HF. The existence of a clear correlation of SEFs with LF or LF/HF may offer a simple approach to estimate the relationship between EEG activity and autonomic nervous system function during sleep.

Adult↗
PubMed2003

Neural mechanism of propofol anesthesia in severe depression: a positron emission tomographic study.

BACKGROUND: The precise neural mechanisms of propofol anesthesia in humans are still unknown. The authors examined the acute effects of propofol on regional cerebral blood flow (rCBF) using positron emission tomography in patients with severe depression. METHODS: In six severely depressed patients (mean age, 55.0 yr) scheduled for electroconvulsive therapy, anesthetic levels were monitored by electroencephalography, and rCBF was serially quantified in the awake, sedated, and anesthetized states. The authors used high-resolution positron emission tomography with 15O-labeled water and statistical parametric mapping 99 for imaging and analysis of the data. RESULTS: Global cerebral blood flow showed sharp decreases from the awake level during the administration of propofol, decreasing 26.8% in the sedated state and 54.4% in the anesthetized state. Moreover, a dose effect was seen in both parietal cortices and the left lateral prefrontal region with larger regions of relative decrease in rCBF at higher propofol doses. At the higher dose, the values of rCBF in the pulvinar nucleus of the thalamus, the pontine tegmentum, and the cerebellar cortex were also affected. Meanwhile, there were few changes of relative rCBF in the basal frontal lobes during both sedated and anesthetized states. CONCLUSIONS: As in earlier studies using normal subjects, pronounced suppression in rCBF in the brain stem reticular formation, the thalamus, and the parietal association cortex occurred even in severely depressed patients. However, previously reported decreases in rCBF in the basal frontal lobe were absent in depressed patients.

Adult↗
PubMed2003

Health-related quality of life of Japanese patients with chronic heart failure: assessment using the Medical Outcome Study Short Form 36.

Chronic heart failure is characterized by impaired cardiac function, but the relationship between clinical indices and subjective perception is not clear. This study was undertaken to investigate the relationship between cardiac function, exercise capacity and clinical classification, and the health-related quality of life (HRQOL) in 91 outpatients with an left ventricular ejection fraction (LVEF) less than 40%. Exercise capacity was evaluated by the Specific Activity Scale, and HRQOL by the Medical Outcome Study Short Form 36. Exercise capacity and the cardiothoracic ratio were correlated with the HRQOL related to physical functioning, although the correlation between exercise capacity and mental health was not significant. LVEF was not related to HRQOL. Factor analysis revealed (1) LVEF was independent of physical functioning; (2) physical function and exercise capacity comprise a factor reflecting physical HRQOL; and (3) socio-emotional functioning is the third factor independent of LVEF and physical function. Physical and socio-mental HRQOL measurement included information independent of the widely used clinical indices such as LVEF and New York Heart Association classification. The evaluation of HRQOL should be included in the assessment of patient status.

Aged↗