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Y Hirasawa

Publications and source records attributed to Y Hirasawa.

At least 19 recordsLinked to original sources
PubMed2002

Second-generation intramedullary supracondylar nail for distal femoral fractures.

The objective of this study was to review the use of intramedullary supracondylar (IMSC) nails for distal femoral fractures. We reviewed 24 fractures treated with second-generation IMSC nails. The fractures consisted of 18 type A1, one type A2, two type C1, one type C2, and two type C3 fractures. The relationships between clinical results and fracture type, approaches, and patient age were retrospectively reviewed. All fractures healed clinically and radiographically. Twenty-one patients maintained gait performance equivalent to that before injury. Average operating time was 108 min +/- 43 min. ROM in the knee of all patients was -5 degrees +/- 6 degrees in extension and 102 degrees +/- 38 degrees in flexion. Extension lag was influenced by surgical approach. The final knee arc was inversely correlated to patient age (R: 0.49, P<0.05). There were three varus/valgus deformities, two cases with loosening, and two with breakage of the distal locking screws, but no failure of the nail itself. Second-generation IMSC nailing for distal femur fractures was satisfactory in patients younger than 60 years of age.

Adult↗
PubMed2002

NOR-1: a nitric oxide releasing agent for calibrating low levels of nitric oxide by the chemiluminescence method.

Nitric oxide (NO) is formed in small amounts in vivo and is rapidly oxidized by interacting with oxygen, making measurement of its level difficult. The chemiluminescence assay is the most widely used method for detecting NO and is extremely sensitive to very small amounts of NO. However, it is difficult to prepare small amounts of NO to be used as a standard for NO analysis. NOR-1, a derivative of NOR-3, is a newly discovered NO donor with rapid NO-releasing activity. We assessed the dynamics of NO release and decomposition using NOR-1. Our results demonstrate that NOR-1 is stable in dimethylsulfoxide (DMSO) and is able to dilute at lower concentration (to picomolar levels) by DMSO without decomposition. NOR-1 released persistently 1.4 more excess of NO with 15 min of incubation. There was a linear relationship between the concentration of NOR-1 and that of NO released from NOR-1 (r=0.997) These findings suggest that NOR-1 is a useful reagent for the calibration of lower NO detection.

Benzoates↗
PubMed2001

Intradiscal solid phase displacement as a determinant of the centripetal fluid shift in the loaded intervertebral disc.

STUDY DESIGN: The movement of cross sections of the monofilament nylon threads inserted into the axially loaded intervertebral disc was traced with magnetic resonance imaging (MRI). This technique allowed the observation of the sequential solid phase displacement of the loaded intervertebral disc. OBJECTIVES: To clarify sequential solid phase displacement of the axially loaded intervertebral disc to elucidate the cause of centripetal fluid shift within a disc. SUMMARY OF BACKGROUND DATA: We already have reported that there is a centripetal fluid shift within the axially loaded intervertebral disc during the early phase of loading. We assumed that there should be an elaborate intradiscal matrix displacement that generates a pressure gradient within the disc to cause a centripetal fluid shift. METHODS: Thirteen freshly obtained bovine caudal intervertebral discs were prepared. Three to five monofilament nylon threads were inserted into each disc in the anterior-posterior direction to trace the intradiscal solid phase displacement on the midcoronal MR images. Sequential displacement of the disc matrix was recorded during a 294 N axial loading. RESULTS: Relatively large centrifugal expansion at the inner layer of the anulus fibrosus compared with less centrifugal expansion of the outer anulus fibrosus was observed in accord with gradual creep of the disc thickness. CONCLUSIONS: The uneven displacement of the intradiscal solid phase observed in the present study expels the fluid phase from the inner anulus fibrosus, thus resulting in accumulation of fluid phase in the nucleus pulposus. The present study suggests the presence of a mechanism that retains water within the normal intervertebral disc, in spite of an external load, because it forms a water-abundant nucleus pulposus, which is surrounded by an anulus fibrosus with decreased water permeability caused by fluid loss. A more detailed analysis is required to clarify topographic volumetric changes within the disc.

Animals↗
PubMed2001

Blood flow and blood volume in the femoral heads of healthy adults according to age: measurement with positron emission tomography (PET).

OBJECTIVE: To deepen understanding of hemodynamics in the femoral head, i.e., the essential factor in clarifying pathogenesis of hip disorders, this study examined blood flow and blood volume in the femoral heads of healthy adults, and their changes with age, by using positron emission tomography (PET). METHODS: In 16 healthy adult males (age: 20-78 years old, mean age: 42 years), blood flow was measured by means of the H2(15)O dynamic study method, and blood volume was measured by means of the (15)O-labeled carbon monoxide bolus inhalation method. RESULTS: Blood flow was 1.68-6.47 ml/min/100 g (mean +/- SD: 3.52 +/- 1.2), and blood volume was 1.67-6.03 ml/100 g (mean +/- SD: 3.00 +/- 1.27). Blood flow significantly decreased (p < 0.01) with age, and blood volume significantly increased (p < 0.05). CONCLUSION: PET was useful in the measurement of blood flow and blood volume in the femoral heads. With age, physiological hemodynamic changes also increased in femoral heads.

Adult↗
PubMed2001

Ceramic endoprosthesis for aggressive giant cell tumors near the knee: eight cases followed for more than 10 years.

Eight patients with locally aggressive giant cell tumor were treated with marginal resection and implantation of a ceramic endoprosthesis with a non-hinged knee joint. The patients have been followed-up for between 10 to 16 years. Newly formed bone appeared at the junction between implant and cortex and in 2 cases subsidence of the implant was seen. All the patients had good function of the knee and no revision was needed.

Adult↗
PubMed2001

Initial experience with off-pump coronary artery bypass grafting.

Off-pump coronary artery bypass grafting (OPCAB) is clearly preferable for patients with extracardiac complications. The aim of this study was to evaluate the initial outcome of OPCAB, and its validity for patients with extracardiac complications. One hundred and fifty-seven consecutive coronary artery bypass graft (CABG) patients were divided into two groups: 30 OPCAB patients and 127 on-pump CABG patients. The early outcomes of the two groups were compared. Preoperatively, OPCAB patients had more extracardiac risk factors than on-pump CABG patients. There were no differences in age or cardiac function between the groups, but the off-pump group had a higher incidence of previous surgery, cerebrovascular disease, and renal failure. There were no differences in graft patency, stroke, or mortality between the two groups, even though the OPCAB patients had more risk factors than the on-pump patients. Our initial experience with OPCAB showed that it is acceptable for high-risk patients in view of the serious nature of their extracardiac condition.

Aged↗
PubMed2001

Minimum ten-year follow-up clinical and radiographic results of Mark I and Mark II Lord type femoral component in total hip arthroplasty.

The purpose of this study was to evaluate the clinical and radiographic results in 103 hips in 88 patients who had cementless primary Lord type femoral component (stem), with a mean follow-up of 11.8 years (range, 10 to 16 years). The original diagnoses were: osteoarthritis in 77 hips, rheumatoid arthritis in 15, and osteonecrosis of the femoral head in 11. Clinical results were assessed using the Harris hip score. Biological fixation, stem full-fit ratio in the intramedullary canal, and bone remodeling were evaluated by X-ray findings. The average clinical hip scores were: 47.1 points preoperatively, 81.7 points at 1 year, 86.6 points at 5 years, 79.0 points at 10 years, and 76.8 points at 15 years. By setting the endpoint at the time when loosening was radiologically confirmed, the 10-year survivorship of the femoral component was 96.9%, and the 16-year survivorship was 95.9%. The full-fit ratio between the bone implant interface just after surgery showed a significant relationship to stability of the femoral component. The decrease in the hip score at 10 years was caused by aseptic loosening of the acetabular threaded cup. However, the femoral component was stable for more than 10 years after the operation. In conclusion, long-term acceptable durability can be expected with the Lord type femoral component.

Adult↗
PubMed2001

Time-sequential changes in biomechanical and morphological properties of articular cartilage in cryopreserved osteochondral allografting.

This study examined time-sequential changes in the biomechanical and morphological properties of articular cartilage that had received cryopreserved osteochondral allografting. Osteochondral blocks obtained from the femurs of 18 rabbits were cryopreserved with dimethylsulfoxide (DMSO), using a two-step freezing method, and allografted to the femurs of another 18 rabbits. Specimens for biomechanical and morphological examinations were prepared at the second, fourth, and twelfth weeks after allografting (n = 18). In 12 allografted rabbits, biomechanical features were examined with an indentation test apparatus, and histological changes were studied with a light microscope (second week, n = 4; fourth week, n = 4; twelfth week, n = 4). In the other 6 allografted rabbits, cartilage surfaces were studied with a scanning electron microscope (second week, n = 2; fourth week, n = 2; twelfth week, n = 2). For controls, fresh, DMSO-treated, or DMSO-treated + cryopreserved specimens were examined biomechanically and morphologically. In the time-sequential examination of biomechanical features, both the parameter for elasticity (i.e., ratio of instant elastic strain to maximum strain) and the parameter for viscosity (i.e., average retardation time) significantly changed. Light microscopy showed chronological decreases in safranin-O staining intensity in the matrix, and progression of degeneration. On scanning electron microscopy, disruption of the cartilage surface was also recognized. Therefore, changes in biomechanical properties due to cryopreservation could cause irreversible changes in the cartilage in cryopreserved osteochondral allografting.

Animals↗
PubMed2001

Fibrin monomer could be a useful predictor of pulmonary embolism after total hip arthroplasty: preliminary report.

We examined 17 total hip arthroplasty patients in order to develop a method for the predictive diagnosis of pulmonary embolism (PE) after joint arthroplasty. Scintigraphy revealed the presence of PE in 4 patients. Prothrombin time (PT), activated partial thromboplastin time (aPTT), antithrombin III (ATIII), and thrombin-AT III complex (TAT) did not show significant differences between patients with and without PE. D-dimer 7 days after surgery showed significant differences between patients with and without PE. Fibrin monomer (FM) increased sharply after surgery, and it was significantly different between the patients with and without PE immediately after surgery and 2 days after surgery. Our findings suggest the importance of FM in the predictive diagnosis of pulmonary embolism after total hip arthroplasty, and 40 microg/ml or higher levels with our measurement method could represent a high-risk condition.

Aged↗
PubMed2001

Cationic polymer-mediated genetic transduction into cultured human chondrosarcoma-derived HCS-2/8 cells.

The usefulness of three types of cationic polymer, i.e., degraded polyamidoamine (PAMAM) dendrimer (SuperFect Transfection Reagent; Oiagen), linear polyethylenimine (PEI; ExGen 500; Euromedex), and branched PEI in gene delivery into chondrocytes was examined comparatively. A plasmid vector containing the Escherichia coli LacZ (pSES.beta) was combined with one of the three cationic polymers at various molar ratios and the resultant complex (polyplex) was used to transduce a human chondrocyte-like cell line, HCS-2/8. Gene expression was evaluated by an O-nitrophenyl beta-D-galactopyranoside (ONPG) assay and by staining with 0.05% 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-gal; Nacalai Tesque). The ONPG assay showed that the highest delivery rate was achieved when 2microg of pSES.beta was combined with either 21 microg of dendrimer, 1.7microg of linear PEI, or 2.0microg of branched PEI. At the same DNA/polymer ratios, the proportions of X-gal-stained cells were also the highest (31.3 +/- 7.5%, 30.3 +/- 9.0%, and 8.3 +/- 3.1%, respectively). LacZ expression reached the highest level 3 days after the dendrimer-mediated transduction, and gradually declined, returning to the background level on day 14. Possible cytotoxicity was examined by trypan blue staining and phase contrast microscopic observations. Neither cytotoxicity nor morphological change was induced at the optimal dose of each polymer. The cationic polymers, particularly the degraded dendrimer and linear PEI, would be a useful nonviral vector for gene delivery to cells of chondrocytes.

Bone Neoplasms↗
PubMed2001

Osteonecrosis of the femoral head that developed after long-term topical steroid application.

This is a report of a 52-year-old man who developed osteonecrosis of the femoral head (ONF) following long-term application of steroid for facial eczema. Before hip pain appeared, the patient had applied 2-3g/day of 0.05% clobetasol propionate for 2 years and 10 months. This steroid is classified as being in the strongest category. ONF was diagnosed based on radiographic and magnetic resonance imaging findings, and the patient received surgical treatment for both hips. ONF was also confirmed by pathological examination of a specimen obtained from the right femoral head during surgery. Because there were no risk factors for ONF besides topical steroid application, this case was considered as ONF associated with topical steroid. Even when steroids are for external use, their dosage and administration should be monitored, and the risk of ONF should also be considered.

Administration, Topical↗
PubMed2001

Initial changes of non-traumatic osteonecrosis of femoral head in fat suppression images: bone marrow edema was not found before the appearance of band patterns.

The present study examined initial changes in non-traumatic osteonecrosis of the femoral head (ONF) on T1- and T2-weighted MR images, and fat suppression images. The subjects were 57 renal transplant recipients (37 males and 20 females), whose median age at the time of transplantation was 31.5 years old (range, 10 to 58 years). Twelve patients developed band patterns (sign of established ONF) at an early postoperative period. Among them, 4 joints of 3 patients had a localized, faint signal abnormality in fat suppression images, where band pattern was confirmed later in T1- and T2-weighted images. In all the 57 patients, no bone marrow edema preceding to ONF was observed. Bone marrow edema would not be the cause of ONF in renal transplant patients. Early changes depicted in our fat suppression images would be useful information in the studies on pathogenesis of ONF.

Adult↗
PubMed2001

Prediction of mechanical properties of healing fractures using acoustic emission.

The objective of this study was to develop a non-destructive method for monitoring fracture healing with acoustic emission (AE). Experimentally produced fractures of the rat femur were tested in tension and in torsion at 4, 6, 8 and 12 weeks after fracture. AE signals were monitored during these mechanical tests. The values for load and torque at the initiation of the AE signal were defined as new mechanical parameters. The apparent density and ash density of the fracture site were also measured at each time period. Tensile strength, tensile stiffness, maximum torque and torsional stiffness of the fracture site increased with time. The AE signal was detected before complete specimen failure. Load and torque for initiation of AE increased proportionally with increasing mechanical properties. The mineral density, however, reached a plateau at 8 weeks, when callus mechanical strength was approximately 50% of control. Load for initiation of AE was strongly correlated with the strength (r = 0.98), stiffness (r = 0.88), and failure strain (r = -0.63) of the callus. Torque for initiation of AE was highly correlated with the maximum torque (r = 0.95) and torsional stiffness (r= 0.93) of the callus. The findings of the present study indicated that some mechanical properties of healing fractures could be estimated by monitoring AE signals.

Acoustics↗
PubMed2001

Hyaluronan suppressed nitric oxide production in the meniscus and synovium of rabbit osteoarthritis model.

Nitric oxide (NO) plays an important role in cartilage degeneration, and NO donors induce meniscus degeneration and synovium inflammation. This study evaluated the effect of intraarticular injections of hyaluronan (HA) on NO production in meniscus and synovium using an experimental osteoarthritis (OA) model. Thirty-six New Zealand white rabbits underwent unilateral anterior cruciate ligament transection (ACLT), and were divided into three groups. Four weeks after ACLT, the HA group started to receive intraarticular HA injections once a week for 5 weeks; the vehicle group started to receive the carrier of HA; and the no injection group, no treatment. All ACLT knees were harvested at the 9th week. Meniscus and synovium sections were examined by immunohistochemistry for nitrotyrosine. The pieces of these two tissues were cultured for 24 h. Culture supernatants were analyzed for nitrite concentration. The amount of NO produced by the meniscus was much larger than that produced by the synovium. NO productions in the meniscus and synovium of the HA group were significantly lower than those of the other groups. The results suggest that the inhibition of NO production in meniscus and synovium might be a part of the mechanism of the therapeutic effect of HA on OA.

Animals↗
PubMed2001

Sympathetic skin response evoked by respiratory stimulation as a measure of sympathetic function.

OBJECTIVES: To compare respiratory and electrical methods of evoking a sympathetic skin response (SSR). METHODS: SSRs evoked by both electrical and respiratory stimulation were recorded from the palms of 47 healthy volunteers. Expiration and inspiration were used as separate stimuli. The correlation coefficients between the amplitude and latency of the SSR from the palm electrodes and the various components of heart rate variability were calculated. RESULTS: Waveform patterns of the SSRs obtained from electrical stimulation showed varied responses to and habituation to this type of stimulation. On the other hand, no subjects showed a phase change in SSR waveform patterns between the first and last expiratory stimuli. The potentials recorded after expiratory stimulation had significantly greater amplitudes than those recorded after electrical stimuli. The low frequency component of heart rate variability induced by expiratory stimulation was significantly greater than that induced by electrical stimulation. The SSR may also correlate strongly with the change of respiratory rate since a more rapid pressure change occurs during expiratory movement than during inspiratory movements. CONCLUSIONS: The SSR evoked by expiratory stimulation is more reliable than either electrical stimulation or inspiratory stimulation for determining sympathetic function.

Adult↗
PubMed2001

Warthin-like tumor variant of papillary thyroid carcinoma: case report and literature review.

A tumor approximately 4.0 x 3.0 cm in size with a cystic change was observed in the left lobe of the thyroid gland of a 52-year-old woman. The removed tumor had lymph follicle formation with a germinal center. This lymphatic tissue showed papillary and island-like growth; the growths were surrounded by atypical epithelium showing nuclear features of papillary carcinoma. The atypical epithelium had ground-glass nuclei with nuclear grooves, clearly indicating intranuclear cytoplasmic inclusion bodies. No chronic thyroiditis was observed in the background of the patient. Parts of the metastatic lymph nodes had cells with an eosinophilic cytoplasm, clearly showing an intratumor lymph follicle formation, as in the primary lesion. This is a rare case of thyroid papillary carcinoma similar to Warthin's tumor of the salivary gland. Here we present this case, with a review of previously published reports.

Adenolymphoma↗
PubMed2001

Dialysis-related amyloidosis of the heart in long-term hemodialysis patients.

BACKGROUND: Dialysis-related amyloidosis (DRA) predominantly occurs in the osteoarticular structures, but it also systemically appears in the extra-articular tissues as well. However, the pathological characteristics of DRA in the hearts of hemodialysis (HD) patients have rarely been reported. METHODS: We studied the pathological characteristics of DRA in the hearts of 18 HD patients, including its relationship to calcification. Furthermore, we studied the immunohistochemical localization of advanced glycation end products (AGEs) using monoclonal anti-imidazolone and anti-Nepsilon-(carboxymethyl)lysine (CML) antibodies. RESULTS: beta2-microglobulin (beta2m) amyloid deposits were detected in the hearts of seven patients who had undergone HD for more than 10 years. beta2m amyloid deposits in the left atrium were localized in the endocardium, the myocardium, and the walls of small blood vessels, whereas in the left ventricle, they were localized only in the walls of small blood vessels. The extent and prevalence of DRA in the heart were severe in the patients on HD for more than 15 years. Most calcification areas near mitral valve were dotted with beta2m amyloid deposits, while diffuse fine calcification was localized within the beta2m amyloid tissues in some cases. Imidazolone and CML were localized not only in massive beta2m amyloid deposits, but also in cardiac myocytes. CONCLUSION: DRAs were localized extensively in the hearts of long-term HD patients. A strong affinity was observed between beta2m amyloid deposits and calcification.

Adult↗