Biomedical subjects

T Nishii

Publications and source records attributed to T Nishii.

At least 37 records · Page 2Linked to original sources

PubMed2001

Glucose intolerance, plasma insulin levels, and colon adenomas in Japanese men.

Hyperinsulinemia may be related to colon carcinogenesis. Several studies have suggested that diabetes mellitus is related to increased risk of colon cancer. We examined cross-sectionally the relation of fasting plasma insulin levels and glucose tolerance status to colon adenomas. In a consecutive series of 951 men undergoing total colonoscopy for a health examination at the Japan Self Defense Forces Fukuoka Hospital from April 1998 to August 1999, we identified 233 cases of colon adenomas and 497 controls with normal colonoscopy. Glucose tolerance status was determined by a 75-g oral glucose tolerance test, and subjects were classified as normal, impaired glucose tolerance (IGT) or non-insulin dependent diabetes mellitus (NIDDM). Plasma insulin levels were measured after subjects had fasted overnight. Logistic regression analysis and analysis of covariance was used to control for age and obesity. While plasma insulin levels were unrelated to colon adenomas, NIDDM was associated with a significantly increased risk of colon adenomas. There was no association between IGT and colon adenomas. NIDDM was more strongly associated with proximal colon adenomas. The findings suggest that long-term hyperinsulinemic status associated with NIDDM may increase the risk of colon adenomas, and subsequently of colon cancer.

Adenoma↗

PubMed2001

Bone scintigraphy for osteonecrosis of the knee in patients with non-traumatic osteonecrosis of the femoral head: comparison with magnetic resonance imaging.

OBJECTIVE: To determine whether technetium bone scintigraphy (BS) is useful for screening of non-traumatic osteonecrosis of the knee (ONK), which was a major affected site, secondary to the femoral head, among multiple osteonecrosis, in patients with non-traumatic osteonecrosis of the femoral head (ONFH). METHODS: A total of 214 knee joints in 107 patients with ONFH were evaluated by BS and a comparison made with magnetic resonance imaging (MRI). ONK was classified into five sites, including the femoral condyles (ONFC), distal femoral metaphysis (ONFM), tibial plateau (ONTP), proximal tibial metaphysis (ONTM), and patella (ONP). RESULTS: Based on the diagnosis by MRI, ONK was detected in 103 knees of 62 patients (48%). ONFC was most common (86 knees, 40%), ONFM (15%), followed by ONTM (10%), ONP (3%), and ONTP (0.9%). Sensitivity, specificity, and accuracy of BS for ONFC detection were 63%, 71%, and 68%, respectively. When the ONFC lesions on the coronal views of MRI were large or medium sized and occupied two thirds, or the entire anteroposterior joint surface on the sagittal views, the sensitivity of BS for ONFC detection increased to 89% (34/38 knees). The sensitivity of BS for ONFM, ONTM, and ONP detection was 3%, 0%, and 0%, respectively, but these lesions showed a low likelihood of collapse. CONCLUSION: BS is useful for screening large ONK in patients with ONFH given that 89% of patients with ONFC who had a high risk of collapse of the knee were identified.

Adolescent↗

PubMed2001

Phase transformation of a zirconia ceramic head after total hip arthroplasty.

We report two cases of surface deterioration of a zirconia ceramic femoral head associated with phase transformation after total hip arthroplasty. One head was retrieved at revision due to recurrent dislocation after six years and the other because of failure of the locking mechanism of the polyethylene liner after three years. The monoclinic content of the zirconia ceramics rose from 1% to about 30% on the surface of the heads. SEM revealed numerous craters indicating extraction of the zirconia ceramics at the surface. Surface roughness increased from an initial value of 0.006 microm up to 0.12 microm. This is the first report to show that phase transformation of zirconia ceramics causes deterioration of the surface roughness of the head in vivo after total hip arthroplasty.

Female↗

PubMed2000

MR findings of necrotic lesions and the extralesional area of osteonecrosis of the femoral head.

OBJECTIVE: To investigate the MR findings of necrotic lesions and the extralesional area of osteonecrosis of the femoral head (ONFH) for each of the radiological stages. DESIGN AND PATIENTS: Forty-nine hips in 29 patients (15 female, 14 male; mean age 38 years, range 17-59 years) were imaged using a 1.0-T superconducting magnet. T2-weighted spin echo pulse sequences (T2WI), spoiled gradient recalled echo pulse sequences (SPGR) and fat suppression SPGR (FS-SPGR), followed by Gd-DTPA enhanced fat suppression SPGR (Gd-FS-SPGR), were all obtained with the aid of a TORSO surface coil. RESULTS AND CONCLUSIONS: While a normal fat intensity area with a low-intensity band on SPGR (band pattern) was seen in 16 of 16 stage 1 (100%), nine of 11 stage 2 (82%), four of 17 stage 3 (24%), and none of five stage 4 hips, all hips showed peripheral rim enhancement on Gd-FS-SPGR (100%). This enhancement band on Gd-FS-SPGR corresponded to histological findings of necrotic trabecular bone, repaired marrow, and fibrous reparative tissue. Bone marrow edema was also clearly demonstrated as a diffuse, high-intensity area outside this enhancement band on Gd-FS-SPGR in two stage 2 (18%), 12 stage 3 (71%), and one stage 4 hip (20%). In cases at stage 2 or more advanced stages with homogeneous or inhomogeneous low intensity on nonenhanced MRI, the reparative process both inside and outside the necrotic lesion, including bone marrow edema, was detected clearly on contrast-enhanced MRI.

Adolescent↗

PubMed2000

Optimizing femoral anteversion and offset after total hip arthroplasty, using a modular femoral neck system: an experimental study.

To investigate the effectiveness of a modular femoral neck system, consisting of two neutral and four types of retroverted necks for the correction of femoral anteversion and offset in total hip arthroplasty, an experimental study was carried out, using sawbones with four different angles of femoral anteversion (16 degrees, 34 degrees, 47 degrees, and 59 degrees ). With the neutral neck, reconstruction of the preoperative anteversion and offset in the normal femur was achieved. While the 15 degrees retroverted long neck was effective for the mildly or moderately anteverted femur, this retroverted neck showed insufficient correction for the severely anteverted femur. This modular neck system proved to be useful for correction of the medial component of femoral offset in femora with anteversion of less than 47 degrees. For patients with greater anteversion, a feature which is rarely seen in the clinical situation, femoral necks with a greater degree of retroversion may be useful.

Arthroplasty, Replacement, Hip↗

PubMed2000

Serial magnetic resonance imaging in a non-traumatic rabbit osteonecrosis model: an experimental longitudinal study.

We investigated the time-dependent natural course of experimental osteonecrosis (ON), including initial changes in ON and the reparative process, using in vivo serial repetitive magnetic resonance imaging (MRI) in a non-traumatic rabbit serum sickness ON model. Some necrotic lesions were detected at 1 week (3 of 16 femora with necrotic lesions) and some in the metaphysis were detected by 12 weeks (2 of 6 femora with lesions) on T(1)-weighted, T(2)-weighted, and fat suppression T(1)-weighted images. On contrast-enhanced MRI, extravasation of the erythrocytes was detected at 72 h (7 of 26 femora with lesions) as a small, focal enhanced area. Necrotic lesions were detected in all abnormal femora by 6 weeks (16 of 16 femora with lesions) as focal, homogeneously or inhomogeneously enhanced areas. Reparative tissue replaced with new vascular and trabecular formation in necrotic areas was detected as an extended marginal enhanced area at 12 weeks. These results suggest that the enhancement patterns on contrast-enhanced MRI may provide helpful information about the developmental and reparative process of clinical ON.

Animals↗

PubMed2000

Osteonecrosis of the patella in patients with nontraumatic osteonecrosis of the femoral head: MRI findings in 60 patients.

We examined both knees in 60 patients with nontraumatic osteonecrosis of the femoral head with three-dimensional MRI. We found osteonecrosis of the patella in 9 patients (10 knees) and osteonecrosis of the femoral or tibial condyles/metaphyses in 35 patients (61 knees). In the patella, the necrosis was located in the proximal half and tended to develop in patients with other necrotic lesions in the knee.

Adolescent↗

PubMed2000

Evaluation of periprosthetic bone-remodeling after cementless total hip arthroplasty. The influence of the extent of porous coating.

BACKGROUND: Total hip arthroplasty changes the levels of stress within the proximal part of the femur, and the femur remodels adjacent to the prosthesis. The stem size and the initial bone-mineral density around the distal portion of the stem affect postoperative bone-remodeling after the insertion of a fully porous-coated metal-cancellous prosthesis. The purpose of this study was to evaluate the influence of the extent of porous coating of this prosthesis on femoral bone-remodeling. METHODS: A longitudinal examination of sixty-one hips in fifty-four patients was performed. Thirty-one hips in twenty-seven patients with a fully porous-coated stem (Group A) and thirty hips in twenty-seven patients with a proximally porous-coated stem (Group B) were followed for twenty-four to thirty months. Periprosthetic bone-mineral density was measured with dual-energy x-ray absorptiometry at specific intervals after the operation. RESULTS: In both groups, the greatest loss of bone-mineral density, compared with the initial (three-week) value, was approximately 20 percent in zone 7 at twelve to eighteen months. In other zones, bone-remodeling appeared to cease by twelve months. At the last follow-up evaluation, the loss of bone-mineral density in the distal and middle regions in Group A was significantly greater than that in Group B (p < 0.01 for zone 3 and p < 0.05 for zone 6). In contrast, with the numbers available, there were no significant differences in loss of bone-mineral density in the proximal regions (zones 1 and 7) between the two groups at any follow-up period. CONCLUSIONS: The extent of porous coating affects bone-remodeling in the distal periprosthetic region rather than in the proximal region. The results in the present report are specific to the particular implants that were studied.

Absorptiometry, Photon↗

PubMed2000

[Reduced signal intensity of T2 weighted MR imaging of thalamus and putamen in multiple sclerosis in Japan].

Although studies using magnetic resonance imaging (MRI) in multiple sclerosis (MS) patients have focused on findings in the white matter because of its demyelination pathogenesis, Drayer et al. have reported a high incidence of low signal intensity on T2 weighted MR imaging (MRI) in gray matter such as the thalamus and putamen. In Japan there has been no investigation of MRI findings of the basal ganglia in MS patients. Therefore, we attempted to examine the incidence and clinical significance of the imaging phenomenon in 34 Japanese patients with MS (12 male, 22 female, ages 18-54 years). As it is well known that the spinal cord and optic nerves are more frequently involved in MS than the brain in Japanese patients, we divided the patients into two subgroups based on their clinical features and the major sites of demyelination on MRI. One group included the 17 patients whose demyelinations occurred in the brain (brain-type), and the other group included the 17 patients whose abnormalities were found in the spinal cord with or without optic nerve involvement (non-brain type). As a control, MRI studies were also performed in age-matched patients with headache without any neurological signs. On T2 weighted MRI, decreased signal intensity in the thalamus was found in only four patients with MS, 11.8% of the total number examined, and in the putamen in three patients with MS, 8.8% of the total examined. All of the patients who showed abnormal decreased signal intensity in the thalamus and/or putamen belonged to the brain-type group, and these incidences were 23.5% in the thalamus and 17.6% in the putamen among the brain-type patients. No patient belonging to the non-brain type showed this imaging sign. This imaging sign was well correlated with the degree of white matter abnormalities in the brain estimated as a score according to modified Callanan et al.'s method. In addition, this sign was also correlated with the expanded disability status scales (EDSS) in the brain-type patients. These observations suggest that the axonal damages due to severe demyelination may induce the impaired transport of iron resulting in an accumulation of ferritin in the thalamus and putamen, and would cause decreased signal intensity on T2 weighted MRI. The relatively low incidence of decreased signal intensity in the thalamus and putamen in this study may be associated with differences in the clinical phenotype of MS between Japan and the USA. In brain-type patients the evaluation of basal ganglia on T2 weighted MRI may be a useful tool for estimating patients' disabilities.

Adolescent↗

PubMed1999

Angiotensinogen gene-activating elements regulate blood pressure in the brain.

Although the angiotensinogen gene is a possible candidate as a determinant of hypertension, the molecular mechanisms of tissue angiotensinogen gene regulation have yet to be clarified. We identified essential transcription regulators of angiotensinogen production in the central nervous system using synthetic double-stranded oligodeoxynucleotides (ODNs) as "decoy" cis elements to block the binding of nuclear factors to promoter regions of the targeted gene. Using a gel mobility shift assay, angiotensinogen gene-activating element (AGE) 2 binding protein was detected in the brain nuclear extracts of both spontaneously hypertensive rats (SHRs) and normotensive Wistar Kyoto rats (WKYs). Importantly, the binding activity of AGE 2 and angiotensinogen mRNA level were significantly higher in the brain of SHRs than in that of WKYs. Using the decoy approach, we demonstrated a significant decrease in the blood pressure of SHRs by transfection of AGE 2 decoy, but not mismatched, ODNs into the lateral cerebroventricle, accompanied by a significant decrease in brain angiotensinogen concentration and mRNA, and angiotensin II level. That these effects, demonstrated herein, are due to central effects is confirmed by the fact that no changes in circulating levels of angiotensinogen or angiotensin II concentrations were observed. Notably, AGE 2 decoy ODNs did not decrease the blood pressure of WKYs. We conclude that the abnormal expression of AGE 2 binding protein in the central nervous system plays a crucial role in high blood pressure of a genetically hypertensive rat model.

Angiotensinogen↗

PubMed1999

Stem length and canal filling in uncemented custom-made total hip arthroplasty.

We reviewed 60 custom-made femoral components of two different lengths : 125 mm (group A) and 100 mm (group B), in order to investigate the relationship between stem length and canal filling in uncemented custom-made total hip arthroplasty. There were no statistical differences between the two groups in age, gender, height, body weight, canal flare index, or bowing angle of the femur. Postoperatively there was no statistical difference between the two groups in the proximal canal filling, but significant difference in the distal canal filling (75.5% vs 85.8% on the anteroposterior view and 76.0% vs 82.5% in the lateral view, P<0.001). The distal canal filling inversely correlated with the ratio of the proximal portion and the distal portion of the stem curvature on the lateral view (lateral curve ratio of the stem, P=0.002). We conclude that superior filling at both the proximal and the distal levels can be obtained by using 100-mm custom made components with a small lateral curve ratio.

Adult↗

PubMed1999

MR evaluation of the articular cartilage of the femoral head during traction. Correlation with resected femoral head.

OBJECTIVE: The purpose was to evaluate the articular cartilage of the hip joint with MR during traction and compare the findings with the resected specimen or arthroscopic findings. MATERIAL AND METHODS: Eight healthy volunteers, 5 patients with osteonecrosis, 5 with acetabular dysplasia, and 5 with advanced osteoarthrosis underwent MR imaging to evaluate the articular cartilage of the hip joint. Coronal fat-suppressed 3D spoiled gradient-echo (SPGR) images were obtained during traction. Identical imaging was performed of all the resected femoral heads of the osteonecrosis and advanced osteoarthrosis patients, and was correlated with the macroscopic pathological findings. RESULTS: The traction was effective and the femoral articular cartilage was clearly identified in all 8 control subjects, and in all cases of osteonecrosis and acetabular dysplasia. In 4 cases of osteonecrosis, chondral fracture was identified in the boundary between the necrosis and the normal area. In all cases of advanced osteoarthrosis, cartilage was identified only at the medial side. The MR images of osteonecrosis and advanced osteoarthrosis corresponded well with the MR images of the resected femoral heads and the macroscopic findings. CONCLUSION: Fat suppressed 3D-SPGR during continuous leg traction was useful in detecting cartilage abnormalities.

Adult↗

PubMed1999

Prevention of renal damage by angiotensin II blockade, accompanied by increased renal hepatocyte growth factor in experimental hypertensive rats.

Hepatocyte growth factor (HGF) is a unique growth factor that has many protective functions against renal damage. Our previous study demonstrated that HGF stimulated the growth of endothelial and epithelial cells without the replication of mesangial cells. Moreover, angiotensin (Ang) II significantly decreased local HGF production in mesangial cells. Therefore, we examined the effects of Ang II blockade on renal HGF expression and renal damage in experimental hypertensive rats. An angiotensin-converting enzyme inhibitor (cilazapril; 10 mg. kg(-1). d(-1)), an Ang II type 1 receptor antagonist (E-4177; 30 mg. kg(-1). d(-1)), hydralazine (8 mg. kg(-1). d(-1)), and vehicle were administered to 16-week-old stroke-prone spontaneously hypertensive rats (SHR-SP) for 3 weeks. Renal damage was evaluated with a computer analysis system, and renal HGF mRNA was measured by Northern blot analysis. Blood pressure of SHR-SP was significantly decreased by all drug treatments compared with vehicle. Moreover, cilazapril, E-4177, and hydralazine significantly decreased the thickening and necrosis of blood vessels compared with vehicle. Similarly, degeneration and necrosis of glomeruli were also markedly improved by cilazapril and E-4177 (P<0.01). We next examined the effects of Ang II blockade on renal HGF expression in SHR-SP. Renal HGF mRNA was markedly decreased in SHR-SP compared with Wistar-Kyoto rats, although Ang II blockade by cilazapril and E-4177 but not hydralazine significantly increased renal HGF mRNA in SHR-SP. Ang II blockade significantly increased renal HGF (a protective growth factor for tubular epithelial cells); thus, we examined tubular histological appearance. Degeneration and necrosis of tubules were significantly improved by cilazapril and E-4177 treatment (P<0.01). In addition, cell infiltration into the glomeruli and hemorrhage were also significantly reduced in SHR-SP treated with cilazapril or E-4177. The present data demonstrated the prevention of renal damage by Ang II blockade in SHR-SP, which was accompanied by a significant increase in renal HGF mRNA. Given the strong mitogenic activity and antiapoptotic actions of HGF on endothelial and epithelial cells, we believe that increased local HGF production by the blockade of Ang II may improve renal function in hypertension.

Angiotensin II↗

PubMed1999

Activation of the brain angiotensin system by in vivo human angiotensin-converting enzyme gene transfer in rats.

The possibility of the brain-specific expression of a component of the renin-angiotensin system was evaluated in the present study. We used the hemagglutinating virus of Japan-liposome complex to transfect human angiotensin-converting enzyme (ACE) cDNA, driven by the cytomegalovirus enhancer and beta-actin promoter, into the lateral cerebroventricle of male Sprague-Dawley rats. We evaluated the time course of hemodynamics, the tissue levels of angiotensin (Ang) II and vasopressin, and ACE activity. Intracerebroventricular transfection of the human ACE gene increased both blood pressure and heart rate. Transfected rats exhibited higher concentrations of brain Ang II and increased brain ACE activity. This activation of the brain angiotensin system was accompanied by increased vasopressin production. The increases in blood pressure and heart rate were abolished by intracerebroventricular administration of an ACE inhibitor or Ang II type 1 receptor antagonist. The expression of the transgene was widely distributed in the periventricular cell layer, the cortex, the hypothalamic nuclei, and the brain stem. Expression in the neuronal cells persisted for up to 14 days. Thus, this hemagglutinating virus of Japan-liposome method is a highly efficient system for gene delivery and is extremely useful for functional gene transfection. This novel hypertensive model may enable characterization of the functions of the renin-angiotensin system in the brain and determination of its role in the pathogenesis of hypertension.

Angiotensin II↗

PubMed1998

Computed-tomography-based computer preoperative planning for total hip arthroplasty.

For precise preoperative planning in total hip arthroplasty (THA), we developed a technique of computed tomography (CT)-based computer preoperative planning and compared this technique with the single X-ray and template method generally used. The subjects of this study were 42 hips in 38 patients who underwent THA using a cementless total hip system. Preoperatively, a standard anteroposterior X-ray of the hip was taken, and conventional preoperative planning was done with a template of the total hip system. Transverse images were obtained using a helical CT scanner, and a CT-based computer preoperative plan was performed on true coronal slice images of the proximal femur reconstructed from CT data. Postoperatively, 29 hips (69%) showed good proximal fit of the femoral component to the medial endosteal line. Of the 20 hips with good proximal fit on preoperative X-ray planning, 12 hips had good proximal fit on postoperative X rays. Sensitivity and specificity of the proximal fit on X-ray templating were 41 and 23%, respectively. In 27 of 28 hips with good proximal fit on reconstructed CT images preoperatively, the postoperative X ray revealed good proximal fit. Sensitivity and specificity of the proximal fit on computer planning were 93 and 86%, respectively. Twelve hips with good proximal fit on preoperative templating, the reconstructed images, and the postoperative X ray had 20 degrees or less of combined femoral neck anteversion and external rotational contracture of the hip on the X-ray table. Eight hips with good proximal fit on preoperative templating and proximal poor fit on the reconstructed images had 17-65 degrees of combined version and rotational contracture. In 16 hips with poor proximal fit on preoperative templating and good proximal fit on the reconstructed images, the combined version and rotational contracture ranged from 17 to 69 degrees. When combined femoral neck anteversion and external rotational contracture of the hip is less than 15 degrees, the simple X-ray and template method might be sufficient for THA planning. Otherwise, the CT-based method of preoperative planning is recommended.

Arthroplasty, Replacement, Hip↗

PubMed1998

Articular cartilage evaluation in osteoarthritis of the hip with MR imaging under continuous leg traction.

We conducted MR evaluations of acetabular and femoral cartilages in 27 hips of patients with osteoarthritis and 10 hips of normal volunteers by a fat-suppressed three-dimensional (3D) pulse sequence using a continuous leg traction method, and correlated the results with radiographic assessment. Normal condition of the acetabular and femoral cartilages was clearly demonstrated in the normal volunteers. Grading of abnormalities was possible for each cartilage in the patients with osteoarthritis. In early osteoarthritis graded by radiography, a high prevalence of abnormalities was detected in the acetabular cartilage as compared with the femoral cartilage. Despite the structural difficulty in evaluation of the hip joint cartilage, our MR imaging technique can provide information concerning a wide spectrum of cartilage abnormalities even in the identical radiographic stage, which will lead to improvement in the evaluation of disease progression and in surgical planning.

Adult↗

PubMed1998

[The Osaka concept. "Dome osteotomy" with of without labrum resection].

Acetabular dysplasia represents the most common aetiology for secondary osteoarthritis of the hip joint in Japan. On radiographs progress of the disease can be classified in four stages (I to IV). Labral lesions are common accompanying findings in acetabular dysplasia, representing an important prognostic factor. Therefore we routinely use conventional arthrography to classify labral lesions in three types (normal, torn and detached). From 1978 to 1983 a modified Chiari osteotomy of the pelvis (dome osteotomy) was performed in 64 hip joints without arthrotomy. The preoperative radiography showed labral lesions in 66%. After an average follow-up of 4 years, 43 of the 44 patients with a normal or torn labrum showed excellent or good results. On contrast, 50% of the 20 patients with a detached labrum showed fair and poor results only. From 1984 to 1989 an arthrotomy was combined with dome osteotomy in 29 hip joints and labral lesions had to be resected in 16 cases. The results were generally good in patients with arthrosis grade I and II, but in stage III they were only fair. Thus, the success of labral surgery can only be achieved in early stages of dysplasia. Based on our findings dome osteotomy combined with arthrotomy and labral surgery can be recommended in patients with labral lesions and hip dysplasia grade I and II.

Acetabulum↗

PubMed1997

Longitudinal evaluation of time related bone remodeling after cementless total hip arthroplasty.

Bone remodeling after cementless total hip arthroplasty was evaluated by dual energy x-ray absorptiometry in a longitudinal study of 32 hips. After insertion of a fully porous surface anatomic stem made of cobalt chromium, bone mineral density was analyzed until at least 2 years postoperatively. Bone remodeling was evaluated in terms of regional bone density changes in the seven adjacent periprosthetic zones as well as the global change in bone density distribution over the entire periprosthetic area. At 12 months after the operation, the averaged regional bone mineral density in all seven zones showed a rapid decrease, ranging from 9% to 24% of the bone mineral density present at 2 weeks postoperatively. Thereafter, the bone density change appeared to be stabilized. The global change in the bone density distribution was expressed as two summarizing statistical indexes derived from principal component analysis: the first index represents the change of average bone mineral density over the entire periprosthetic area, and the second represents the severity of bone mineral density decrease in the proximal area versus the distal area. The second index proved that more bone density reduction occurred in the proximal area, but this was variable among patients and correlated significantly with the stem size and the initial bone mineral density in the distal part of the periprosthetic area. This longitudinal dual energy x-ray absorptiometry study suggests that a large part of the bone remodeling after cementless hip arthroplasty ceases within 1 year postoperatively, and stem size and the initial bone density around the distal portion are important considerations for predicting the proximal bone density decrease during the early rapid remodeling period.

Absorptiometry, Photon↗