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Biomedical subjects

Y Koike

Publications and source records attributed to Y Koike.

At least 55 records · Page 3Linked to original sources
PubMed2000

Novel wedge-shaped doubly inclined chamber for the flow-through separation of suspended particles

Combined standing and propagating wave modes have previously been successfully used by the authors for simultaneous agglomeration and transportation of small particles suspended in still water. The present study of this method with flowing water, using a 120 x 350 x 13 mm3 agglomerator, confirmed that the proposed method is applicable with suspended SiO2 particles of varying size. The process was found to be most efficient at flow rates below a certain threshold, which varies with particle size. This threshold was found to be 5 ml/s for a particle size of 7.9 microns at an ultrasonic frequency of 2 MHz corresponding to 0.74 mm wavelength. The existence of a maximum particle transport velocity was demonstrated.

Journal Article↗
PubMed2000

Tau protein is a potential biological marker for normal pressure hydrocephalus.

A biological marker for normal pressure hydrocephalus (NPH) is beneficial for evaluation of its severity and of indications for shunt operation. Tau protein was initially considered as a biological marker in cerebrospinal fluid (CSF) from Alzheimer's patients. Recently, it has been demonstrated that degeneration in the brain causes elevation of tau in CSF. Therefore, the tau level in CSF from NPH patients was evaluated. Tau levels in CSF from NPH patients were significantly higher than that in controls. The tau levels were correlated with the severity of dementia, urinary incontinence, and gait disturbance in NPH. These results suggest that CSF tau may be useful as a biological marker for NPH to determine the level of neuronal degeneration.

Aged↗
PubMed2000

Decrease of CD56(+)T cells and natural killer cells in cirrhotic livers with hepatitis C may be involved in their susceptibility to hepatocellular carcinoma.

CD56(+)T cells and CD56(+)natural killer (NK) cells are abundant in the human liver. The aim of this study was the further characterization of these cells in the liver with or without hepatitis C virus (HCV) infection. Liver mononuclear cells (MNC) were isolated from liver specimens obtained from the patients during abdominal surgery. In addition to a flow cytometric analysis, liver MNC and PBMC were cultured with the immobilized anti-CD3 Ab, IL-2, or a combination of IL-2 and IL-12 and their IFN-gamma production and the antitumor cytotoxicity were assessed. The liver MNC of HCV (-) patients contained 20% CD56(+)T cells whereas the same proportions decreased to 11% in chronic hepatitis livers and to 5% in cirrhotic livers. The proportion of NK cells also decreased in the cirrhotic livers. On the other hand, the populations of these cells in PBMC did not significantly differ among patient groups. The IFN-gamma production and the cytotoxicity against K562 cells, Raji cells, and a hepatocellular carcinoma, HuH-7 cells, greatly decreased in the cirrhotic liver MNC. In contrast, the cytotoxicity in PBMC did not significantly differ among the patient groups and was lower than that in the liver MNC of HCV (-) patients. CD56(+)T cells and NK cells but not regular T cells purified from liver MNC cultured with cytokines showed potent cytotoxicities against HuH-7 cells. These results suggest that a decreased number of CD56(+)T cells and NK cells in cirrhotic livers may be related to their susceptibility to hepatocellular carcinoma.

Aged↗
PubMed2000

Risk factors for recurring hepatocellular carcinoma differ according to infected hepatitis virus-an analysis of 236 consecutive patients with a single lesion.

Patients with hepatocellular carcinoma (HCC) frequently experience intrahepatic HCC recurrence even after complete ablation of primary lesions. Because the oncogenic process may be different for hepatitis B viral (B-viral) and hepatitis C viral (C-viral) HCC, the present study was conducted to elucidate the factors contributing to HCC recurrence with respect to the infected hepatitis virus. Two hundred thirty-six patients with a single HCC lesion who underwent complete ablation of the tumor by PEIT and/or PMCT or surgical resection at Tokyo University and its affiliated hospitals from 1993 to 1997 were enrolled. The patients were classified into 3 groups: the B-viral group, C-viral group, and NBNC group. After complete removal of tumors, the patients were followed for a mean period of 39 months. The factors contributing to HCC recurrence were analyzed by univariate and multivariate analysis using the Cox proportional hazard model. The rate of intrahepatic recurrence in enrolled patients at 1, 3, and 5 years was 19%, 50%, and 64%, respectively. The intrahepatic recurrence rate in C-viral and B-viral HCC was higher than that in the NBNC-related HCC. Fibrosis staging, pathological grading of HCC, and serum AFP levels were significantly linked to intrahepatic recurrence by univariate analysis, and fibrosis staging was strongest in the multivariate analysis for C-viral HCC (P = .004). In contrast, fibrosis staging did not affect the recurrence in B-viral (P = .51) and NBNC-related (P = .77) HCC. Risk factors for HCC recurrence differed according to the infected viral state.

Aged↗
PubMed2000

Multi-layer energy filter for realizing conformal irradiation in charged particle therapy.

A new type of filter for charged particle radiotherapy is developed to reduce unwanted dose transfer to the normal tissues around a tumor. The new filter can make a static irradiation field where the width of the spread-out Bragg peak (SOBP) is two-dimensionally adjusted. That makes the field conformal to the tumor three-dimensionally. The filter is made of many layers produced by using stereolithography. The layer has a miniaturized structure that has geometrical similarity to the conventional ridge filter. Shapes of cone and pyramid are also usable for the unit-cell constructing the layer. The spread of the field in the depth direction is decided by the thickness of the filter, or by the number of layers. The experimental result of the irradiation using the ridge-type construction shows a good agreement with an estimate by the Monte Carlo calculation. By combining this technique with intensity modulation that has lateral position dependence, the conformal irradiation can be achieved by a simple procedure.

Equipment Design↗
PubMed2000

The effect of the prostaglandin I2 analogue OP-2507 on adrenaline-induced pulmonary edema in rabbits and analysis of hemodynamic changes.

This study was carried out to understand the onset mechanism of adrenaline (ADR)-induced pulmonary edema (PE) and the effect of drugs related to the arachidonate cascade in a rabbit model. ADR was administered intravenously by a bolus injection to the rabbits at 50, 75 and 100 microg/kg. To evaluate the severity of PE, the lung-water ratio (LWR) was calculated as a ratio of the difference between wet and dry lung weight to dry lung weight. The PE incidence and LWR exhibited a dose-dependent increase, and LWR correlated with the left atrial pressure (LAP). The involvement of the arachidonate cascade was evaluated by the co-administration of flurbiprofen, a cyclooxygenase inhibitor; ozagrel, a thromboxane synthase inhibitor; and OP-2507 (15-cis-(4-n-propylcyclohexyl)-6,17,18, 19,20-pentanor-9-deoxy-6,9-alpha-nitriloprostaglandin F1 methyl ester), a prostaglandin I2 analogue. Co-treatment of the rabbits with ADR and flurbiprofen resulted in an increase in LAP and the incidence of PE, whereas co-administration of ozagrel did not exhibit any significant changes in the measured parameters. Conversely, OP-2507 reduced the LAP, PE incidence and LWR when co-administered with ADR. Rabbits co-treated with OP-2507 displayed an improved cardiac function. The results of these studies demonstrated the effectiveness of OP-2507 in protecting the lung and cardiac function from the ADR-induced PE.

Animals↗
PubMed2000

Involvement of apoptosis in the endotoxemic lesions of the liver and kidneys of piglets.

The involvement of apoptosis was evaluated in lesions of endotoxemic piglets. A single injection with E. coli O111:B4 lipopolysaccharide (LPS) induced foci of coagulative necrosis in the liver and kidneys. No significant change was observed in these organs at 1.5 hr after LPS injection, but at 6 hr, epithelial cells with chromatin condensation or fragmentation and apoptotic bodies were visible. Foci of coagulative necrosis were formed within 24 hr after LPS inoculation. In and adjacent to the necrotic foci, dead hepatocytes with nuclear condensation or fragmentation were scattered. These dead cells were positively stained by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) methods. Electronmicroscopy revealed apoptotic cells with condensed or fragmented homogeneous nuclear chromatin, and necrotic cells with irregularly destroyed nuclei and cytoplasmic membranes. Apoptotic cell death were also observed in parietal cells of the stomach and lymphocytes in the lymphatic system. DNA ladders with approximately 200-bp multimers were observed in hepatic, renal and thymic samples prepared after 6 and 24 hr of LPS injection by agarose gel electrophoresis. These results suggest that apoptosis is involved in the pathology of swine endotoxemia.

Animals↗
PubMed2000

Age related differences in electroencephalographic and cardiac arousal at the termination of sleep apnea/hypopnea.

OBJECTIVE: The purpose of the present study was to determine whether electroencephalographic (EEG) and cardiac arousal, i.e. heart rate elevation at the termination of apnea/hypopnea are related to aging. METHODS: The subjects were 13 middle-aged (40-60 years of age, 47.8+/-5.35 years) and 10 elderly (>60 years of age, 69.8+/-5.31 years) male patients with obstructive sleep apnea syndrome. We evaluated the number of apneas per an hour of sleep (apnea index: AI), the number of hypopneas per an hour of sleep (hypopnea index: HI), the summation of HI and AI (apnea/hypopnea index: AHI), sleep stage, the amount of time during which nocturnal oxygen saturation was decreased below 90% (oxygen desaturation time: ODT), and EEG and cardiac arousal at the termination of apnea/hypopnea using polysomnography with pulse oximetry. RESULTS: There was no significant difference in AHI, duration of apnea/hypopnea, and sleep stage distribution between the two groups. However, the ratio of apnea/hypopnea with EEG and cardiac arousal was significantly higher in middle-aged than in elderly patients. The ratio of HI to AHI was significantly lower in middle-aged than in elderly patients. In middle-aged patients, EEG and cardiac arousal were significantly correlated with AI, AHI, and ODT, whereas, in elderly patients, these parameters were not similarly correlated. CONCLUSION: Our findings suggest that the differences in EEG and cardiac arousal, and the pattern of sleep-disordered breathing (SDB) between middle-aged and elderly patients with SDB might be a physiological phenomenon of aging.

Adult↗
PubMed2000

[Influence of diabetes mellitus and complications on long-term outcome of coronary artery bypass surgery].

The influence of diabetes mellitus and complications on the long-term outcome of coronary artery bypass graft surgery (CABG) was investigated in 192 consecutive patients who underwent elective CABG between January 1992 and March 1996. Of these, 102 patients were diabetic and 90 were nondiabetic. Preoperative and postoperative left ventricular ejection fraction, number of grafts, use of arterial conduit, and frequency of perioperative infarction were all similar in the 2 groups. During a mean follow-up of 3.2 years, diabetics showed higher cardiac mortality than nondiabetics (15% vs 3%, p = 0.01). Cardiac event-free survival was also low in diabetics, and this difference increased throughout the period (91% vs 99% at 2 years, 74% vs 90% at 4 years in diabetics and nondiabetics, respectively, by Kaplan-Meier analysis, p = 0.008). Multivariate Cox regression analysis revealed postoperative low ejection fraction and diabetes mellitus as independent predictors of late cardiac death. Major causes of cardiac death in diabetics were sudden death, pump failure and acute myocardial infarction. Additionally, subgroup analysis in diabetics using the Cox regression model identified postoperative low ejection fraction, female gender and diabetic nephropathy as independent predictors of late cardiac death. Thus, patients with diabetes have a worse clinical outcome after CABG, especially when associated with low ejection fraction, female gender and diabetic nephropathy. Intensive management of heart failure, prevention of myocardial infarction and specific strategy for female patients are all essential to improve the long-term outcome of diabetics after CABG.

Aged↗
PubMed2000

[Percutaneous tumor ablation therapy for the advanced stage of HCC].

We have performed percutaneous tumor ablation (PTA) including percutaneous ethanol injection therapy (PEIT) for 90% of the patients with hepatocellular carcinoma. Until December 1998, the 793 patients received PTA, 5 years survival rate reached 39.8%. Excluding the patients with Child C whose hepatic function were extremely low, 5 years survival rate reached to the level of 41.2%. Since 5 years survival rate in stage IV-A reached 24.4%, the patients of stage IV-A may be considered to have an indication for PTA. We have confirmed the effectiveness of the local treatment including radiotherapy for advanced hepatocellular carcinoma with portal vein invasion. We are attempting to perform PTA for the extra-hepatic lesions that had no indication of other treatment. However the indication of PTA is limited by the presence of diffuse nodules, exacerbation of the hepatic function, or tumor invasion to portal vein, bile duct, inferior vena cava.

Carcinoma, Hepatocellular↗
PubMed2000

[Power spectrum analysis of heart rate variability to orthostatic challenge in cases of Binswanger's encephalopathy].

The autonomic nerve activity was evaluated in cases of Binswanger's encephalopathy by power spectrum analysis of heart rate variability during supine rest and standing upright, in order to elucidate the role of autonomic nervous system function in the pathophysiology of Binswanger's encephalopathy. There was no difference in the ratio of low frequency (LF) power to high frequency (HF) power (L/H ratio), which reflects cardiac sympathetic nerve activity in each position among Binswanger's encephalopathy, control and lacunar stroke. Binswanger's encephalopathy had significantly lower HF power, which reflects cardiac parasympathetic nerve activity, than control and lacunar stroke in a supine rest, and HF power did not respond to standing. Moreover, there was no difference in HF power between mild cases and severe cases of Binswanger's encephalopathy, and L/H ratio decreased in severe cases during standing. These results suggest that cardiac parasympathetic nervous system function is impaired in the early stage of Binswanger's encephalopathy, then cardiac sympathetic nervous system dysfunction occurs with advancing the disease stage.

Aged↗
PubMed2000

[A one-month combined use of selective adrenergic beta 1- and alpha 1-agonists for postprandial hypotension in patients with autonomic failure].

In 1993, we reported the pathophysiology of postprandial hypotension (PPH) in patients with sympathetic dysfunction: a fall of BP resulted from both excess systemic vasodilation and lack of compensatory increase of cardiac output and vascular resistance in the leg arteries. In that article, we showed the beneficial results of combined oral administration of denopamine (a selective beta 1-agonist) and midodrine HCI (a selective alpha 1-agonist) on this condition. The present study was undertaken to further evaluate the efficacy and safety of this agonist combination in autonomic failure (AF) patients with PPH. This was a one-month trial. A total of 13 chronic AF patients received orally 30 mg of denopamine and 12 mg of midodrine three times a day, 30 minutes before each meal. We measured brachial BP every 10 min in the daytime and every 15 min in the nighttime, using a 24-h indirect BP recorder. The combined use of these agonists produced a significant improvement in PPH and maintained a near-normal BP level. In conclusion, the combined administration of denopamine and midodrine three times a day is a well-tolerated and efficacious treatment for PPH.

Adrenergic alpha-Agonists↗
PubMed2000

Clinical effects of elastic bandage on neurogenic orthostatic hypotension.

Neurogenic orthostatic hypotension (OH) often causes troublesome symptoms such as dizziness, syncope and falling, interfering active daily life or various therapies in rehabilitation. Nonpharmacologic measures for treating patients with OH include wearing elastic leotard, head-up tilting at night, etc. Elastic garment or antigravity suits is certainly effective, but it may be uncomfortable and not practical. Although elastic bandage (EB) bound on the lower limbs has been thought to be useful, there is few clinical report about its beneficial evidence. We investigated short-term clinical effects of commercially available EB on OH, and estimated the mechanism of its effectiveness by measuring some blood pressure-related humoral variables in neurodegenerative patients with OH.

Aged↗
PubMed1999

Auditory brainstem responses in patients with autonomic failure with Parkinson's disease and multiple system atrophy.

Auditory brainstem responses (ABRs) were examined in six patients with autonomic failure with Parkinson's disease (AF with PD) and 10 patients with autonomic failure with multiple system atrophy (AF with MSA), all of which showed marked parkinsonian features as a principal sign. We designated the central abnormalities of ABRs as prolongation of latencies (wave III or V) and interpeak latencies (IPLs; I-III, I-V, and III-V IPL) or decreased amplitude ratios of wave III or V to those of wave I (less than 1.0). None of the patients with AF with PD showed abnormalities in ABRs. In contrast, in those with AF with MSA, the peak latencies or IPLs were prolonged in two of the 10 patients, and the amplitude ratios of wave III or V to those of wave I were decreased in other two of these patients. Moreover, both prolongation of latencies and a decreased ratio were observed in other one. Overall, five of the 10 patients with AF with MSA showed central abnormalities in ABRs. It is clinically difficult to differentiate AF with PD from AF with MSA, particularly when no cerebellar signs are apparent in AF with MSA patients. When central abnormalities of ABRs are observed in AF patients, AF with MSA should be suspected rather than AF with PD. In conclusion, ABRs provide useful information for the differential diagnosis of AF with PD and AF with MSA.

Aged↗
PubMed1999

Presence of activating transcription factor 4 (ATF4) in the porcine anterior pituitary.

The two-hybrid system that identifies protein-protein interactions in a yeast expression system was used to investigate porcine anterior pituitary transcription factors. Four cDNA clones of a protein interacting with the leucine zipper domain of porcine cJun were obtained. Their nucleotide sequences revealed that they encode activating transcription factor 4 (ATF4). A full-length cDNA of porcine ATF4 was obtained by the polymerase chain reaction, and its deduced amino acid sequence showed 88 and 83% identity to human and mouse ATF4, respectively. Reverse transcription-polymerase chain reaction analysis of mRNAs prepared from 11 porcine tissues demonstrated that ATF4 is ubiquitous. Immunohistochemistry showed that ATF4 is present in the hormone producing cells of the anterior pituitary, but absent in some cells of the anterior pituitary. Further binding analysis revealed that ATF4 also interacts with itself and cFos. This evidence of ATF4 homodimerization, as well as heterodimerization with cJun and cFos in the anterior pituitary suggests a novel mechanism for the regulation of gene expression in this tissue.

Activating Transcription Factor 4↗
PubMed1999

A 1-hour enzyme-linked immunosorbent assay for quantitation of acrolein- and hydroxynonenal-modified proteins by epitope-bound casein matrix method.

A simple and rapid enzyme-linked immunosorbent assay (ELISA) method for quantitation of acrolein and 4-hydroxy-2-nonenal (HNE)-modified proteins was developed. Microtiter plate wells were precoated and blocked simultaneously with epitope-bound bovine caseins as matrix proteins, and aldehyde-modified proteins were quantitated by a competition assay with a monoclonal antibody specific for acrolein-modified lysine or HNE-modified histidine epitopes. Minimal reaction times required for the coating/blocking; first monoclonal antibody and the peroxidase-conjugated second antibody binding steps were 3, 3, and 7 min, respectively, the former two steps being found to be or akin to diffusion-rate-limiting reactions. The convenient ELISA should find an application for analyses of the intricate processes involved in oxidative stress and carcinogenic insult. The epitope-attachment methodology may also be advantageous for the quantitation of various other biologically important haptenic molecules.

Acrolein↗