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Biomedical subjects

S Kitamura

Publications and source records attributed to S Kitamura.

At least 127 records · Page 7Linked to original sources
PubMed2000

Semi-automatic ROI placement system for analysis of brain PET images based on elastic model: application to diagnosis of Alzheimer's disease.

UNLABELLED: PET with 18F-fluorodeoxyglucose (FDG) is a useful technique to image cerebral glucose metabolism and to detect patients with Alzheimer's disease in the early stage, in which characteristic temporoparietal hypometabolism is visualized. We have developed a new system, in which the standard brain ROI atlas made of networks of segments is elastically transformed to match the subject brain images, so that standard ROIs defined on the segments are placed on the individual brain images and are used to measure radioactivity over each brain region. We applied this methods to Alzheimer's disease. METHODS: This method was applied to the images of 10 normal subjects (ages 55 +/- 12) and 21 patient clinically diagnosed as Alzheimer's disease (age 61 +/- 10). The FDG uptake reflecting glucose metabolism was evaluated with SUV, i.e. decay corrected radioactivity divided by injected dose per body weight in (Bq/ml)/(Bq/g). RESULTS: The system worked all right in every subject including those with extensive hypometabolism. Alzheimer patients showed markedly lower in the parietal cortex (4.0-4.1). When the threshold value of FDG uptake in the parietal lobe was set as 5(Bq/ml)/(Bq/g), we could discriminate the patients with Alzheimer's disease from the normal subjects. The sensitivity was 86% and the specificity was 90%. CONCLUSIONS: This system can assist diagnosis of FDG images and may be useful for treating data of a large number of subjects; e.g. when PET is applied to health screening.

Adult↗
PubMed2000

Benzodiazepine receptor distribution and cerebral blood flow in early blindness--a PET study.

We studied benzodiazepine receptor (BZR) distribution, which is thought to be affected by neuronal density in the cerebral cortex, and CBF using [11C]flumazenil and [15O]water PET in early blind (EB) and in blindfold sighted control (SC) subjects. PET images were co-registered to the subject's MRI. Using SPM96, MRI images were normalized in the Talairach and Tournoux coordinate system, and accordingly MRI-registered PET images were spatially normalized. Statistical parametric maps were computed on a voxel-by-voxel basis, using the general linear model. CBF for EB was significantly larger in the Brodmann area 17 and 18, especially anterior area, than that for SC, while there was no significant difference in BZR distribution. Our BZR data suggest that the amount of neurons do not change due to early visual deprivation in the visual cortex, in spite of high CBF in visual cortex of EB subjects.

Adult↗
PubMed2000

[An experience with the Ross operation utilizing cryopreserved pulmonary homografts procured by and stored in our homograft valve bank].

Eight patients, 4 males and 4 females ranging in age from 10 to 54 years (mean 27 +/- 13 years) underwent the Ross operation using a cryopreserved pulmonary homograft harvested by and cryopreserved in our institutional "Tissue Bank". Seven patients had a congenital bicuspid aortic valve and 3 patients had had healed infective endocarditis of the aortic valve. Four young female patients wanted to have a baby after operation. The Ross procedure was carried out utilizing aortic root replacement techniques in all patients. All patients survived and are currently in NYHA class 1, but 2 cardiac events occurred in 2 patients during the mean follow-up term of 29 +/- 19 months. The one was the anastomic stenosis between the homograft and distal pulmonary artery treated by balloon dilatation and the other was ventricular tachycardia eventually managed by the insertion of an ICD. Pulmonary autograft valve regurgitation is present in 3 patients, but it is not progressive up to the present time. Pulmonary homograft valves function well in all patients. The Ross operation for adolescents and young adults should become more popular along with more easy availability of homograft valves based upon the establishment of the "Homograft Valve Bank" system in Japan.

Adolescent↗
PubMed2000

[Cesarean section in a pregnant patient with placenta percreta involving the urinary bladder].

Placenta percreta involving adjacent structures is serious complication of pregnancy with a high mortality rate. A 32-year-old woman, gravida 4, para 3, who had previously undergone a cesarean section, was admitted to our hospital at 31 weeks' gestation for placenta previa. At 33 weeks' gestation, the diagnosis of placenta percreta with involvement of the urinary bladder was made by ultrasonography and magnetic resonance imaging. At 34 weeks' gestation, an elective cesarean section was scheduled. Anesthesia was maintained with sevoflurane in oxygen before delivery, and with nitrous oxide in oxygen, fentanyl and midazolam after delivery. During the operation, attempts to remove the placenta resulted in massive hemorrhage. Blood loss for the procedure was 13,800 g. Because of the extreme hemorrhage, we encountered hemorrhagic shock and postoperative complications despite the preoperative preparation. In case of placenta percreta, it is essential to prepare adequate volume of blood for transfusion at the start of surgery and secure large bore intravenous lines. A rapid transfusion device may be recommended. Regarding the anesthetic management, general anesthesia is preferable in consideration of the risk of hemorrhagic shock and the length of operation time. Furthermore, we need team approach and preoperative management to prevent the uncontrolled hemorrhage in such a severe case.

Adult↗
PubMed2000

Replacement of the tricuspid valve in children with congenital cardiac malformations.

BACKGROUND AND AIM OF THE STUDY: When replacing the regurgitant tricuspid valve in children, the decision to use either a bioprosthesis or a mechanical valve remains controversial. METHODS: The atrioventricular valve for the pulmonary circulation was replaced in 11 young patients aged between 8 months and 13 years. Complications of congenital cardiac malformation were present in seven patients, and Ebstein's anomaly in three; tricuspid valvular regurgitation was an isolated lesion in one patient. A bioprosthesis was implanted on seven occasions, and a bileaflet mechanical valve on eight, including re-replacement of the valve in four patients. RESULTS: One patient died two years after implantation due to respiratory problems. Tricuspid stenosis due to valve calcification occurred in four bioprostheses at between four and nine years after initial replacement (57%). In three of these cases the native valve leaflets had not been removed. Thrombosis occurred in one patient with a mechanical valve; rereplacement was successful. Anticoagulant-related hemorrhage occurred in another patient. Among patients receiving a mechanical valve, 83% of valves were dysfunction-free after five and ten years. CONCLUSION: When replacing an atrioventricular valve for the pulmonary circulation in children, we prefer to use a low-profile mechanical valve, especially when extensive repair of intracardiac malformation has been carried out, but ventricular function is good. In children with poor cardiac performance, a bioprosthesis is preferred, with total resection of the native valve leaflets.

Adolescent↗
PubMed2000

[Perioperative management of two neonates with severe Ebstein's anomaly with pulmonary atresia].

Ebstein's anomaly appearing during the neonatal period carries a high mortality rate. We report the perioperative management of two neonates with severe Ebstein's anomaly associated with pulmonary atresia. Their chest radiography revealed massive cardiomegaly, with cardiothoracic ratio of 90% and 100%, respectively. Their tracheas were intubated immediately after birth because of severe respiratory distress. The babies were laid in the prone position and one of them was managed with high frequency oscillatory ventilation (HFO) for prevention of pulmonary barotrauma and extensive atelectasis in the preoperative period. On the 4th and 3rd day after birth, respectively, they underwent Starnes procedure which consists of closure of tricuspid valve, enlargement of atrial septal defect, reduction of right atrium and creation of aortopulmonary shunt reported to be a useful palliative treatment for critically ill neonates with Ebstein's anomaly. Case 1 baby could not be weaned from cardiopulmonary bypass because of low cardiac output. Case 2 could not be weaned from extracorporeal membrane oxygenation due to hypoxia. We consider, however, treatment of respiratory failure and lung protection after birth are important for the prognosis. Perioperative use of HFO may be advantageous for the neonate with severe Ebstein's anomaly with pulmonary atresia.

Cardiovascular Surgical Procedures↗
PubMed1999

PPARgamma inhibits the expression of c-MET in human gastric cancer cells through the suppression of Ets.

Activation of peroxisome proliferator-activated receptor gamma (PPARgamma) is shown to inhibit the growth of MKN-45 cells, a human gastric cancer cell line, which overexpresses c-Met tyrosine kinase. The aim of the present study was to investigate whether PPARgamma regulates the expression of c-Met. Two days after the activation of PPARgamma by troglitazone, a potent and selective PPARgamma ligand, a dramatic reduction of c-MET transcripts and the c-Met protein in MKN45 cells was observed. The luciferase assay showed that the activation of PPARgamma suppressed -249 to +330 c-MET promoter activity, driven by cotransfection of ETS-1 expression vector. These data demonstrate that PPARgamma activation is capable of suppressing Ets-induced c-MET gene transcription. Thus, it is possible that the growth inhibitory effect of PPARgamma on MKN-45 cells is related to the suppression of c-MET transcription.

Cell Division↗
PubMed1999

Isolation of different types of birnavirus from ayu Plecoglossus altivelis and amago salmon Oncorhynchus rhodurus cultured in the same geographic area.

A birnavirus was recently isolated from cultured ayu Plecoglossus altivelis on Shikoku island, Japan. The diseased fish displayed vertebral or vertical curvature and mild haemorrhage around the brain. Cytopathic effects (CPE) of the virus, including cell roundness, filamentous change and cell lysis, were observed in CHSE-214, RTG-2 and RSBK-2 cells. The virus isolated from ayu, designated the AY-98 strain, was found to be antigenically related to the marine birnavirus (MABV) Y-6 strain that originated from yellowtail Seriola quinqueradiata. AY-98 had a bi-segmented RNA genome and the same nucleotide sequence in the 310 bp VP2/NS junction as MABV Y-6. At the same time that the ayu epizootics occurred, another birnavirus (AM-98) was isolated from amago salmon Oncorhynchus rhodurus which were cultured 66 km away from the ayu farm. AM-98 showed a similar CPE and had the same host cell ranges as AY-98. However, AM-98 was serologically similar to the VR-299 strain of infectious pancreatic necrosis virus (IPNV) and their nucleotide sequences in the VP2/NS junction region showed 98% homology without changes at the amino acid level. In this study, the ayu strain AY-98 was grouped into MABV, whereas the amago salmon strain AM-98 was grouped into IPNV. This indicates that the 2 birnaviruses originated from different sources in spite of the fact that the places where they were isolated are close to one another. The results in this paper show a new aspect of the traditional consensus that the same serogroup of birnavirus distribute in close geographic areas.

Animals↗
PubMed1999

Effects of photoperiod on salmon GnRH mRNA levels in brain of castrated underyearling precocious male masu salmon.

Previous studies have suggested that activation of salmon gonadotropin-releasing hormone (sGnRH)-producing neurons is induced by the combined effects of photoperiod and steroid hormones in underyearling males of the masu salmon, Oncorhynchus masou. The present study further assesses the effects of photoperiod and steroid hormones on sGnRH synthetic activity and examines the changes in sGnRH mRNA levels in the brains of castrated underyearling precocious male masu salmon by manipulating the photoperiod for 60 days from August through October. In castrated males in which plasma testosterone levels decreased to low levels, sGnRH mRNA levels in the preoptic area (POA) increased under a short photoperiod (8L-16D), whereas they remained at low levels under a long photoperiod (16L-8D) for a 2-month duration. In sham-operated males, sGnRH mRNA levels in the ventral telencephalon and those in the POA increased in October with testicular maturation even under a long photoperiod with a delay of 1 month compared with the short photoperiod group. These results suggest that preoptic sGnRH-producing neurons receive short photoperiodic signals and that either short photoperiod or steroid hormone secretion is required for the activation of sGnRH synthesis in underyearling precocious male masu salmon.

Animals↗
PubMed1999

Preserved benzodiazepine receptors in Alzheimer's disease measured with C-11 flumazenil PET and I-123 iomazenil SPECT in comparison with CBF.

This study evaluates the regional cerebral blood flow (CBF) with H2(15)O-PET and the distribution of central benzodiazepine receptor (BZR) with C-11 flumazenil (FMZ) by PET and I-123 iomazenil (IMZ) by SPECT in Alzheimer's disease (AD). In AD, whereas the CBF was diminished in the frontal, temporal, parietal, and occipital cortex, the distribution volume of FMZ and delayed activity of IMZ were relatively preserved in these cortices, suggesting that the BZR reduction, reflecting neuronal loss, is less prominent than the CBF suppression. The mini-mental state examination score (MMS) was weakly correlated with the CBF in the parietal cortex but not with BZR. It is speculated that the neuronal density reflected by BZR is less impaired than the neuronal function assessed with blood flow in the association cortex of AD. High correlation was found between the uptake of FMZ and the delayed activity of IMZ. The delayed image of IMZ-SPECT is clinically useful to evaluate the preservation of neuronal density in the affected temoporoparietal association cortex in AD.

Aged↗
PubMed1999

Benzodiazepine receptor imaging with iomazenil SPECT in aphasic patients with cerebral infarction.

To investigate the relationship between prognosis of aphasia and neuronal damage in the cerebral cortex, we evaluated the distribution of central-type benzodiazepine receptor (BZR) binding in post-stroke aphasics with [123I]iomazenil and SPECT. We performed iomazenil SPECT in six aphasic patients (aged from 45 to 75 years; all right-handed) with unilateral left cerebral infarction. Three patients showed signs of Broca's aphasia and the other three Wernicke's aphasia. Cerebral blood flow (CBF) imaging was performed with [123I]iodoamphetamine (IMP). The regions of interest (ROIs) on both images were set in the cerebral cortex, cerebellar cortex and language-relevant area in both hemispheres. Three patients were classified in the mild prognosis group and the other three in the moderate prognosis group. The left language-relevant area was more closely concerned with the difference in aphasic symptoms than the right one in both BZR and CBF distribution, but the ipsilateral to the contralateral ratio (I/C ratio) in the language-relevant areas in the BZR distribution was significantly lower in the moderate prognosis group than in the mild prognosis group, although no difference was seen for these values between the two groups in the CBF distribution. These results suggest that BZR imaging, which makes possible an increase in neuronal cell viability in the cerebral cortex, is useful not only for clarifying the aphasic symptoms but also for evaluating the prognosis of aphasia in patients with cerebral infarction.

Aged↗
PubMed1999

Thoracoscopic lung volume reduction surgery for emphysema. Evaluation using ventilation-perfusion scintigraphy.

Thoracoscopic lung volume reduction surgery was conducted in 28 consecutive patients (bilateral 21, unilateral 7). The bilateral procedure was conducted simultaneously in 16 and as a planned staged approach in 5, using stapler resection with Nd:YAG laser ablation. Perfusion and ventilation scintigraphy were used to evaluate status before and after surgery. One operative death (3.6%) due to pneumonia occurred after a simultaneous bilateral procedure. Three to 6 months after surgery, the forced expiratory volume in 1 second (FEV1.0) had improved an average of 44% after the bilateral procedure and 17% after unilateral. Improved ventilation and perfusion distribution in the lower lung field correlated significantly with improved dyspnea scale (p < 0.01). Mean transit time was shortened significantly in each lung field (p < 0.01). Improved mean transit time correlated significantly with improved FEV1.0 and maximum oxygen consumption (VO2max) (p < 0.05). In conclusion, we found that bilateral thoracoscopic lung volume reduction surgery produces short-term functional outcomes superior to those of the unilateral procedure, and should be considered the procedure of choice for most patients. Ventilation and perfusion scintigraphy are useful both in determining target areas for resection and in evaluating lung volume reduction surgery effects.

Aged↗
PubMed1999

Benefits accruing to grafting of the right internal thoracic artery to the left anterior descending artery in coronary artery bypass grafting.

OBJECTIVES: We have investigated the effects and outcome from grafting the right internal thoracic artery to the left anterior descending artery in coronary artery bypass grafting. METHODS: We analyzed the findings in 185 patients who underwent coronary artery bypass grafting involving right internal thoracic artery-left anterior descending artery bypass. The survival rate, cardiac events related to the right internal thoracic artery-left anterior descending artery graft, and graft patency were investigated. In cardiac catheterization, the production of nitric oxide from the endothelium of the internal thoracic artery was measured as the plasma nitrite and nitrate levels by the Griess reaction. The reactions to acetylcholine infusion (5 micrograms) in the right internal thoracic artery (n = 4) were compared to those in the left internal thoracic artery (n = 9) grafts. RESULTS: The hospital mortality rate was 0.5%. The actuarial survival rate at 11 years after operation was 98.81%. The rate of freedom from cardiac events at 11 years after operation was 92.08%. The rate of patency of the right internal thoracic artery-left anterior descending artery was 97.0% in 133 patients. Nitric oxide production was calculated as (total nitrite plus nitrate production in response to stimulation by acetylcholine-total nitrite plus nitrate level before acetylcholine load)/(total nitrite plus nitrate level before acetylcholine load). There was no significant difference in changes in plasma concentration in response to acetylcholine stimulation between the right internal thoracic artery-left anterior descending artery and left internal thoracic artery-left anterior descending artery groups (20 +/- 29% versus 5 +/- 10%). CONCLUSIONS: The right internal thoracic artery-left anterior descending artery grafts exhibited good patency and release of nitric oxide in response to acetylcholine loading, similar to left internal thoracic artery-left anterior descending artery grafts.

Coronary Artery Bypass↗
PubMed1999

Actions of adenosine A2A receptor antagonist KW-6002 on drug-induced catalepsy and hypokinesia caused by reserpine or MPTP.

RATIONALE: Current treatment of Parkinson's disease (PD) is based on dopamine replacement therapy, but this leads to long term complications, including dyskinesia. Adenosine A2A receptors are particularly abundant in the striatum and would be a target for an alternative approach to the treatment of PD. OBJECTIVES: The purpose of this study is to examine the efficacy and potency of the novel selective adenosine A2A receptor antagonist (E)-1,3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dhydro- 1H-purine-2,6- dione (KW-6002) in ameliorating the motor deficits in various mouse models of Parkinson's disease. METHODS: We evaluated the efficacy and potency of KW-6002 and other reference compounds in the selective adenosine A2A receptor agonist 2-[p-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamidoadenosin e (CGS 21680)-, haloperidol- or reserpine-induced catalepsy models. The effect of KW-6002 on reserpine or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride(MPTP)-induced hypolocomotion was also examined. RESULTS: The ED50s of KW-6002 in the reversal of CGS21680-induced and reserpine-induced catalepsy were 0.05 mg/kg, PO and 0.26 mg/kg, PO, respectively. Compared to the ED50 of other adenosine antagonists and dopamine agonist drugs, KW-6002 is over 10 times as potent in these models. KW-6002 also ameliorated the hypolocomotion (minimum effective dose; 0.16 mg/kg) induced by nigral dopaminergic dysfunction with MPTP or reserpine treatment. Combined administrations of subthreshold doses of KW-6002 and L-dopa (50 mg/kg, PO) exerted prominent effects on haloperidol-induced and reserpine-induced catalepsy, suggesting that there may be a synergism between the adenosine A2A receptor antagonist KW-6002 and dopaminergic agents. CONCLUSIONS: To our knowledge, KW-6002 is the most potent and orally active adenosine A2A receptor antagonist in experimental models of Parkinson's disease, and may offer a new therapeutic approach to the treatment of Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1999

Bone scintigraphy and magnetic resonance imaging after transtrochanteric rotational osteotomy.

OBJECTIVE: To assess the ability of bone scintigraphy and magnetic resonance imaging (MRI) to predict the outcome of transtrochanteric rotational osteotomy (TRO) for osteonecrosis of the femoral head (ONFH). DESIGN: This study was a prospective evaluation of imaging techniques. PATIENTS AND METHODS: MRI and bone scintigraphy were performed on 20 hips in 18 patients at 3 months after TRO. The radiographic findings at 3 months after TRO, and the MRI and bone scintigraphic findings, were compared with the radiographic findings at final follow-up (mean 39 months). RESULTS AND CONCLUSIONS: On MRI a low-intensity area or a low-intensity band in the new weight-bearing area extending over the acetabular edge on T1-weighted images was related to the presence of collapse on the radiographs at final follow-up. In hips with an area of absent activity in the new weight-bearing surface on bone scintigraphy, collapse was seen more frequently on radiographs at final follow-up than in hips without this feature. Bone scintigraphy was no more specific than radiography in predicting the outcome after TRO. We consider MRI to be superior to bone scintigraphy in predicting the occurrence of collapse, which is one of the major short-term problems after TRO.

Adult↗
PubMed1999

Variant Gerstmann-Sträussler syndrome with the P105L prion gene mutation: an unusual case with nigral degeneration and widespread neurofibrillary tangles.

We present here a case of variant Gerstmann-Sträussler syndrome (GSS) with a codon 105 mutation of the prion protein gene. A 57-year-old woman developed dementia and gait disturbance dissimilar to the spastic paraparesis that is observed in most cases with codon 105 mutation. The clinical course of the disease in this case was 12 years. The brain weighed 900 g, and the frontal lobe, pallidum and thalamus were markedly atrophic. Severe neuronal loss was observed in the deep layer of the frontal and temporal cortices, and fibrillary gliosis and a marked loss of neurons was observed in the globus pallidus, thalamus and substantia nigra. Many amyloid plaques and some ballooned neurons were present in the frontal, temporal and parietal cortices. However, no spongiform changes were seen. The cerebellum was relatively well preserved. Numerous neurofibrillary tangles (NFTs) were recognized in the cerebral cortices, and scattered NFTs were observed in the basal nucleus of Meynert, thalamus, substantia nigra, periaqueductal gray matter, raphe nuclei and locus ceruleus. The case presented here indicates the presence of variations in the pathological findings of cases with codon 105 mutation, and that the formation of cortical and brain stem NFTs might have something to do with the duration of illness and/or the degree of brain tissue destruction that had occurred.

Brain↗
PubMed1999

Osteonecrosis of the femoral head associated with pregnancy.

A 31-year-old pregnant woman suddenly complained of bilateral hip pain 2 weeks before delivery. She was delivered of triplets by Caesarean section. She had been treated with human menopausal gonadotropin and human chorionic gonadotropin (hMG-hCG) before pregnancy. Radiograms of the hip joint showed collapse of the femoral heads bilaterally. Magnetic resonance imaging revealed a band pattern of low signal intensity for both hips on T1- and T2-weighted images. She had no history of steroid therapy or alcohol abuse. Osteonecrosis of the femoral heads bilaterally associated with pregnancy was confirmed. Pathology of the femoral head showed typical empty lacunae and necrosis of the trabecula.

Adult↗