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Biomedical subjects

S Kitamura

Publications and source records attributed to S Kitamura.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1999

Effects of recombinant human erythropoietin on thrombosis and fibrinolysis in autologous transfusion for hip surgery.

Recombinant human erythropoietin (rHuEPO) is effective in allowing autologous blood donation in patients unable to donate because of anemia. As adverse effects of rHuEPO might include activation of coagulation and possibly fibrinolysis, we investigated these possibilities in the context of autologous blood donation preceding hip surgery. Thirty-seven patients who donated 800 ml of autologous blood for elective hip surgery were randomly assigned to either a group of 20 receiving preoperative treatment with rHuEPO (erythropoietin beta), 6000 U i.v. twice weekly for 3 weeks, or an untreated control group of 17. A significant increase in platelet count was associated with autologous blood donation and intraoperative blood loss with or without rHuEPO. Coagulation and fibrinolysis were increased significantly by intraoperative blood loss in both groups, but not by rHuEPO. Coagulation and fibrinolysis were not activated by rHuEPO for elective hip surgery.

Adult↗
PubMed1999

Predictive factors for mortality and cerebral complications in arteriosclerotic aneurysm of the aortic arch.

BACKGROUND: The incidence of cerebral complications is high in patients with aortic arch aneurysm. METHODS: Between December 1977 and December 1995, 246 patients with arteriosclerotic arch aneurysm underwent operation. Thirty-nine patients had an aneurysm involving the entire arch, 193 had only distal arch aneurysm, and 14 had arch aneurysm extending to the descending aorta. Eighty-seven patients underwent replacement of the total arch, 85 had replacement of only the distal arch, 14 had simultaneous replacement of the descending aorta, 45 had patch repair, and 15 had thromboexclusion. Selective cerebral perfusion was used in 112 patients and partial bypass in 58 in the earlier series of patients, but deep hypothermic circulatory arrest with retrograde cerebral perfusion technique was exclusively applied in the most recent 76 patients. RESULTS: There were 50 (20%) early deaths and 37 (19%) late deaths. Postoperative stroke was found in 26 (11%) patients of which 13 (50%) died. Mutual predictive factors for postoperative mortality and stroke were earlier series, preoperative chronic renal failure, ruptured aneurysm, arch clamping during procedure, and using partial cardiopulmonary bypass. Among 129 patients operated on during the most recent 5 years, early mortality and incidence of stroke decreased to 14.7% and 6.9%, respectively. CONCLUSIONS: Results of operations for arteriosclerotic aneurysms of the transverse aortic arch in 246 patients during a period of 17 years have been improving but are still not satisfactory.

Adult↗
PubMed1999

Surgical treatment of Behçet's disease involving aortic regurgitation.

BACKGROUND: Behçet's disease involving aortic regurgitation is rare, and prosthetic valve detachment after aortic valve replacement is one of the most serious complications reported. We investigated the surgical results in 10 patients with aortic regurgitation caused by Behçet's disease. METHODS: Between 1981 and 1997, 10 patients with aortic regurgitation secondary to Behçet's disease had surgery. There were 8 men and 2 women, and their ages ranged from 33 to 60 years (mean, 46+/-8 years). The surgical procedures for aortic regurgitation were aortic valve replacement in 6 patients and Bentall type operation in 4. RESULTS: No patient died during the hospital stay. The follow-up periods ranged from 11 to 185 months (mean, 87 months). Two patients died during the follow-up period. The acturial survival rate was 89% at 5 years and 67% at 10 years. Prosthetic valve detachment or suture detachment requiring redo operation occurred in 4 patients, 3 of whom had redo operations twice. Four patients had a composite graft replacement, and 1 patient died after the operation. No prosthetic valve detachment was noted in 64% of the patients at 5 years and in 43% at 10 years. CONCLUSIONS: The rate of prosthetic valve detachment was 40% (4 of 10 patients), with a higher incidence in patients with Behçet's disease than in those treated during the same period at the same hospital for aortitis caused by other diseases. Surgical techniques for treatment of this condition should be modified to improve the surgical outcome in these patients.

Adult↗
PubMed1999

Is distal anastomosis only to the true channel in chronic type B aortic dissection justified?

BACKGROUND: We investigated long-term outcomes of the distal false lumen of the aorta and aortic branches after distal anastomosis of the graft only to the true lumen in chronic type B aortic dissection. METHODS: From November 1979 until June 1998, we treated 98 patients without Marfan syndrome who had chronic type B aortic dissection and underwent replacement of the descending aorta, 79 of whom had distal anastomosis to the true lumen only. The celiac artery originated from the false lumen in 11 patients, superior mesenteric artery in 5, right renal artery in 19, and left renal artery in 16. RESULTS: There were 12 (15.1%) early deaths. Spinal cord ischemia was detected in 5 patients. Postoperative follow-up was achieved in 67 patients, and 13 patients died. Postoperative survival at 10 years was 67.6% +/- 7.1%. Eight patients had complete occlusion of the distal false lumen, 54 patients had occlusion of the false lumen down to the celiac artery, and 5 patients had a patent false lumen. Four patients required further replacement of the thoracoabdominal aorta. CONCLUSIONS: In non-Marfan patients with chronic type B aortic dissection, the false lumen distal to the graft anastomosis was likely to be thrombosed when the graft was anastomosed to the true lumen only. Postoperative visceral circulation was not compromised, but spinal cord ischemia is a problem that remains to be solved.

Adult↗
PubMed1999

Autofluorescence in human dentine in relation to age, tooth type and temperature measured by nanosecond time-resolved fluorescence microscopy.

Stationary and dynamic characteristics of autofluorescence in human dentine were examined with a nanosecond time-resolved fluorescence microphotometer. With ageing, the intensity of the fluorescence increased whereas the decay time decreased. There were no differences in fluorescence intensity, decay time or spectral profile among tooth types taken from the same individuals or from individuals of the same age. Fluorescence intensity was enhanced after the application of heat (37 and 50 degrees C), but remained unchanged when specimens were kept at 4 degrees C. These results suggest that the increase in fluorescence intensity was partially due to a temperature-dependent physicochemical mechanism.

Aged↗
PubMed1999

Strain differences of the ability to hydroxylate methotrexate in rats.

Converting activity of methotrexate (MTX) to 7-hydroxymethotrexate (7-OH-MTX) was examined using eight strains of rats. Marked variability of the activity was found in liver cytosols from the rats. The highest activity was observed with Sea:SD rats, followed by LEW/Sea and Jcl:Wistar rats. The lowest activity was observed with WKA/Sea rats. The difference in the activity between Sea:SD and WKA/Sea strains was 104-fold. The variation was correlated to the strain difference of benzaldehyde oxidase activity in the rats. The cytosolic 7-hydroxylase activities in other tissues of Sea:SD rats were much higher than those of WKA/Sea, similarly to the case in liver. The liver microsomes of Sea:SD rats exhibited no 7-hydroxylase activity toward MTX even in the presence of NADPH. The cytosolic 7-hydroxylating activity of the livers of Sea:SD rats was inhibited by menadione, beta-estradiol, chlorpromazine and disulfiram, inhibitors of aldehyde oxidase, but not oxypurinol, an inhibitor of xanthine oxidase. The purified aldehyde oxidase from the livers of Sea:SD rats exhibited a significant 7-hydroxylating activity toward MTX. However, xanthine oxidase had no ability to hydroxylate MTX. These facts suggest that MTX hydroxylating activity in rats is predominantly due to aldehyde oxidase, and the strain differences are due to the variations of the flavoenzyme level.

Aldehyde Oxidase↗
PubMed1999

Catastrophic failure of cementless total hip arthroplasty using a femoral component without surface coating.

Consecutive series of 90 hips that had had a primary cementless arthroplasty with use of straight collarless stems between January 1988 and September 1992 were reviewed. Twenty-eight hips with Omnifit Normalized Stems (Fit-N) and 45 hips with Omniflex Normalized Stems (Flex-N) without porous coatings were compared clinically and radiographically with 17 hips with Omnifit Microstructured Stems (Fit-M) with porous coating. The average follow-up periods for the 3 stems were 97 months, 73 months, and 93 months. Revision was performed or awaited in 9 cases (32.1%) in the Fit-N group, 18 cases (40.0%) in the Flex-N group, and 1 case (5.8%) in the Fit-M group. The average annual subsidence was 0.62 mm/y, 0.73 mm/y, and 0.17 mm/y. Osteolysis of more than 3 mm occurred in 28.6%, 37.8%, and 23.5%. Fit-N stems and Flex-N stems without porous coatings are not appropriate for cementless total hip arthroplasty.

Bone Cements↗
PubMed1999

Elevated plasma brain natriuretic peptide levels in chronic respiratory failure with cor pulmonale.

Elevated plasma brain natriuretic peptide (BNP) levels have been described in patients with congestive heart failure and acute myocardial infarction. We measured plasma BNP levels in patients with chronic respiratory failure to evaluate the correlation between plasma BNP levels and pulmonary haemodynamics. Plasma BNP levels were measured in 28 patients with chronic respiratory failure accompanied by three underlying diseases [14 with chronic obstructive pulmonary disease (COPD), seven with sequelae of pulmonary tuberculosis (sequelae Tbc) and seven with diffuse panbronchiolitis (DPB)] by immunoradiometric assay methods (IRMA). Twenty-one of 28 patients had already received oxygen supplementation and 16 of 21 patients were treated as outpatients with home oxygen therapy. Plasma BNP levels were significantly elevated in patients with chronic respiratory failure complicated by cor pulmonale (81.5 +/- 13.1 pg ml-1) compared to patients without cor pulmonale (13.3 +/- 2.7 pg ml-1, P < 0.001). As controls, plasma BNP levels in 10 patients with primary lung cancer were studied, and the results (3.5 +/- 1.0 pg ml-1) were not significantly different from those of patients with chronic respiratory failure without cor pulmonale. Plasma BNP levels in 12 healthy subjects were also studied, and the results (7.2 +/- 1.0 pg ml-1) were not significantly different from those of the control subjects. Plasma BNP levels showed a weak linear correlation with systolic pulmonary arterial blood pressure, estimated by Doppler echocardiography (r = 0.43; P = 0.068), but there was no significant correlation between BNP levels and the degree of hypoxaemia (r = 0.30; P = 0.138). Plasma atrial natriuretic peptide (ANP) levels in patients with chronic respiratory failure were also measured using the same samples. Plasma ANP levels were also significantly elevated in patients with chronic respiratory failure complicated by cor pulmonale (80.8 +/- 12.1 pg ml-1) compared to patients without cor pulmonale (26.1 +/- 4.4 pg ml-1, P = 0.003). A significant correlation was found between plasma BNP and ANP levels (r = 0.68; P < 0.001). Our results suggest that the plasma BNP or ANP level may be a useful indicator for detecting the presence of cor pulmonale in patients with chronic respiratory failure.

Adult↗
PubMed1999

Use of expanded polytetrafluoroethylene sutures as artificial tendinous cords in children with congenital mitral regurgitation.

OBJECTIVE: To determine the efficacy in the intermediate term of artificial cords inserted in children with congenital mitral regurgitation. METHODS: We reconstructed the tendinous cords using expanded polytetrafluoroethylene (ePTFE) sutures in 11 children with severe mitral regurgitation. In these patients, the aortic (anterior) leaflet of the mitral valve had been markedly prolapsed, the tendinous cords being partially lacking in seven, and elongated in the remaining four. In addition, one of the papillary muscles was hypoplastic in five and absent in three. The number of artificial cords constructed varied from two to six. Conventional annuloplasty was performed in all to plicate the dilated annular attachment of the valve. Ventricular septal defect was present in four patients, and other associated malformations in another two. Age at operation ranged from 9 months to 9 years old, with a mean of 4.5 years. RESULTS: All patients survived the operation. No reoperation has been needed thus far. No complications were encountered related to the use of the prosthetic materials or anticoagulation. As judged by echocardiography, regurgitation became trivial or slight immediately after the repair. In two patients, however, regurgitation recurred within 1 year of the operation. Coaptation between the leaflets was maintained by a compensatory growth at the site of attachment of the artificial cords. Catheterization demonstrated significant improvements in the end-diastolic volume of the left ventricle. CONCLUSION: Expanded polytetrafluoroethylene sutures can be used as artificial cords when attempting to repair the malformed mitral valve in children, providing excellent results in the short- and the intermediate-term after the surgical procedure.

Child↗
PubMed1999

Ventricular outflow tracts after Kawashima intraventricular rerouting for double outlet right ventricle with subpulmonary ventricular septal defect.

OBJECTIVE: To determine whether or not the ventricular outflow tracts can be efficiently constructed in patients with double outlet right ventricle with subpulmonary ventricular septal defect by the Kawashima intraventricular rerouting in which the morphologically right ventricular outlet is divided into two, one for the systemic and the other for the pulmonary circulations. METHODS: The intraventricular rerouting procedure was carried out in nine patients with this particular malformation. Age at repair ranged from 35 days to 3 years old. The distance between the attachments of the tricuspid and the pulmonary valves was 10 mm or greater in all except one patient in whom the measured value was 3 mm. Resecting subaortic musculature appropriately, a tailored patch, either oval-shaped (in seven) or heart-shaped (in two), was placed to construct an unobstructed channel for the left ventricular outflow tract with its diameter greater than that of the anticipated normal aortic orifice at the time of repair. For an unobstructed channel to the pulmonary arteries, enlargement of the right ventricular outflow tract was carried out using a patch in six. RESULTS: All patients survived the operative procedure. On postoperative catheterization, mean pulmonary arterial pressure was 15 +/- 8 mmHg, and cardiac index was calculated as 3.3 +/- 0.6 l/min per m2. It proved that the constructed left ventricular outflow tract can become larger in the longer term. Pressure gradient across the left ventricular outflow tract was greater than 20 mmHg in two patients in the intermediate term. One of these two underwent reoperation for the obstruction 10 years after the initial repair. It was suspected that use of a heart-shaped internal conduit, which seems to result from inadequate conal resection, was one of the possible causes of such obstruction in the longer term. Pressure gradient of 47 mmHg was seen across the right ventricular outflow tract in one patient, although this patient has undergone no reoperation. Enlargement of the right ventricular outflow tract could minimize postoperative obstruction for the pulmonary pathway. CONCLUSIONS: The intraventricular rerouting remains one of the attractive surgical options for repair in this particular setting, in terms of successful construction of the ventricular outflow tracts.

Child, Preschool↗
PubMed1999

The formation of two layers detectable by intraoperative echocardiography is a reliable predictor of late thrombosis within the false lumen of a dissected aorta.

The subjects consisted of one patient with chronic type A and three patients with chronic type B aortic dissection, who underwent replacement of an aorta obliterating distal false lumen. After the repair, the formation of two layers was detected by direct scanning echocardiography within the false lumen even during heparinization. In all cases, postoperative computed tomography confirmed complete thrombosis of the false lumen. The formation of two layers was considered to be a reliable predictor of late thrombosis.

Adult↗
PubMed1999

Early and long-term results of surgery for aneurysms of the thoracic aorta in septuagenarians and octogenarians.

OBJECTIVE: The purpose of this study was to demonstrate early and long-term results of surgery for thoracic aortic aneurysm in patients over 70 years of age compared with those of patients under 70 years and to clarify the clinical problems peculiar to this subset of patients. PATIENTS AND METHODS: Of 1157 patients who underwent surgery for thoracic aortic aneurysm from 1978 to December 1997, 261 who were 70 years or older were selected for analysis. Mean age at the time of surgery was 74.4 +/- 3.5 years. Aneurysms were atherosclerotic in 177 patients and aortic dissection in 84. Acute aortic dissection was found in 25 patients and ruptured aneurysm in 44. The control group consisted of 896 patients under 70 years. Preoperative complications such as AAA, peripheral arterial disease, emphysema, and old cerebral infraction were more common in the older group. Operative procedures consisted of replacement of the ascending aorta or hemiarch in 51 patients, total arch replacement in 75, distal arch replacement in 35, descending aorta replacement in 75, replacement of the thoracoabdominal aorta in 28, and extra-anatomical repair and others in 15. The technique of extracorporeal circulation was selective cerebral perfusion in 69 patients, deep hypothermic circulatory arrest in 90, femoro-femoral bypass in 39, left heart bypass in 12, and temporary aorto-arterial bypass in 30, and others in 21. RESULT: Early mortality was 21% (54 patients), which was greater than that of the control group (113 patients, 13%, P < 0.01). The incidence of postoperative stroke, transient brain dysfunction, and respiratory problems was higher in the study group (P < 0.01 in all). Mean duration in ICU among survivors was 9.3 +/- 20.2 days and that of the control group was 5.9 +/- 2.8 days (P < 0.01). In a recent series (from 1991 to 1997) postoperative mortality improved to 15.6% (30/192 patients) in the study group however this result was still inferior to that of the control group (8.6%, 39/452, P = 0.03) however mortality of emergency surgery during the same periods was still high (31%, 11/35 patients). Logistic regression analysis revealed that significant risk factors for postoperative hospital death were surgery before 1991, age over 70 years, preoperative cardiac problems, aneurysm rupture, postoperative stroke, low output syndrome, bleeding, and acute renal failure. Postoperative follow-up was obtained in 408 patients/year and the longest period was 10.2 years. Late deaths were documented in 31 patients. Five-year and 10-year survival were 61.2 +/- 5.7% and 31.3 +/- 16.4%, respectively. In the control group the 5-year and 10-year survival were 78.0 +/- 2.1% and 62.5 +/- 4.0%, respectively (P = 0.03). However, survival of the early survivors in the study group was similar with that of the age-matched normal population. Aortic reoperation was performed in 13 patients. Freedom from aortic reoperation was 86.7 +/- 4.2% at 5 years and 80.5 +/- 7.1% at 10 years in the study group and 83.4 +/- 1.8% at 5 years and 64.1 +/- 13.3% at 10 years in the control group (P = 0.27). CONCLUSION: Although recent advances have been achieved, early and long-term results of surgery for thoracic aortic aneurysm in patients older than 70 years were less satisfactory compared with those of patients under 70 years of age, especially in patients who required emergency surgery. Preoperative disorder of the vital organ systems was considered to be the main causative factor for high mortality, however, pertinent surgical strategies are necessary to improve the outcome of elderly patients.

Age Factors↗