Biomedical subjects

T Shinozaki

Publications and source records attributed to T Shinozaki.

At least 19 recordsLinked to original sources

PubMed2005

Changes in biochemical parameters after anterior cruciate ligament injury.

We studied the biochemical characteristics of human knees with deficient anterior cruciate ligaments (ACL) and analysed their relationship to the time after ligamentous injury. Thirty-two patients with isolated ACL-injured knees and six healthy volunteers were enrolled. Synovial fluid samples were centrifuged after aspiration during arthroscopic examination, and aliquots of supernatant were frozen and stored at -80 degrees C. The samples were analysed for interleukin (IL)-1beta, tumour necrosis factor (TNF)-alpha, IL-6, matrix metalloproteinase (MMP)-3, and tissue inhibitor of metalloproteinase (TIMP)-1 using commercially available sandwich enzyme-linked immunosorbent assay. In fluid from ACL-injured knees, the average concentrations of IL-6, MMP-3 and TIMP-1 were highly elevated in comparison with normal controls. There was a statistically significant correlation between the concentrations of MMP-3 and IL-6. The IL-6 and TIMP-1 concentrations were interrelated. The concentration of MMP-3 remained high, independent of the duration since the injury, whereas the TIMP-1 and IL-6 levels decreased. The results suggest that the timing of the treatment of an ACL-injured knee might be of importance.

Adolescent↗

PubMed2005

Osteoid osteoma treated with computed tomography-guided percutaneous radiofrequency ablation: a case series.

The nidi of osteoid osteoma are small and difficult to identify precisely; this can necessitate substantial resection of the surrounding normal bone. We applied percutaneous, image-guided radiofrequency ablation to treat 5 patients with osteoid osteoma. The precise location of each nidus was determined using a 3-mm-thick spiral computed tomographic scan. The most appropriate needle pathway was selected to avoid major neural and vascular structures. A 14-gauge core needle was introduced into the nidus and then exchanged for a 17-gauge straight rigid electrode with a 1-cm exposed tip to heat the lesion to 90 degrees centigrade for 5 minutes. Four of the 5 patients were discharged on the day after surgery without any external supports, and were pain-free after a few days. The remaining patient had a pes equinus contracture induced by the penetration of the calf muscles through a posterior approach but was fully recovered 6 days later. The mean follow-up period was 20.6 months. No recurrences or late complications were observed in this series. This case series shows that the computed tomography-guided percutaneous radiofrequency ablation is a simple, minimally invasive, and highly effective technique for the treatment of osteoid osteoma.

Adult↗

PubMed2005

Sites and modes of action of proctolin and the FLP F2 on lobster cardiac muscle.

At the threshold concentration (1-10 pmol l(-1)), the neuropeptide hormones proctolin (PR) and the FLRFamide-like peptide (FLP) F(2) cause an increase in amplitude of electrically evoked contractions (each contraction is a brief tetanus) of lobster heart ostial muscle. At higher concentrations each peptide also induces an increase in tonus (contracture). The PR-induced contracture and augmentation of tetani are proportional to increases in [Ca2+]i. The rate of onset and recovery of peptide-induced effects on both tetani and contracture appeared to reduced by Ca2+ storage by the sarcoplasmic reticulum (SR). Enhanced tetani following a contracture may be due to enhanced voltage-gated Ca2+ current and sarcoplasmic reticular (SR) Ca2+ loading. The SR Ca2+ loading appears to be specific for PR and F2, since glutamic-acid-induced contractures are not followed by increased tetani. The prolonged elevation of [Ca2+]i during contracture causes a right-ward shift in the force-pCa curve indicating a decrease in myofibrillar sensitivity to Ca2+. Blocking voltage-gated Ca2+ channels with Cd2+, nifedipine or verapamil, while reducing tetani, does not prevent peptide-induced contracture and enhanced tetani. Opening SR Ca2+ channels and depleting SR Ca2+ with either caffeine or ryanodine blocked tetani but permitted accelerated peptide-induced contractures. We conclude that PR and F2 at low concentration enhance voltage-dependent Ca2+ induced Ca2+ release from the SR, while higher hormone levels directly gate Ca2+ entry across the sarcolemma.

Animals↗

PubMed2005

Motility and growth of human bone-marrow mesenchymal stem cells during ex vivo expansion in autologous serum.

Human bone-marrow mesenchymal stem cells have an important role in the repair of musculoskeletal tissues by migrating from the bone marrow into the injured site and undergoing differentiation. We investigated the use of autologous human serum as a substitute for fetal bovine serum in the ex vivo expansion medium to avoid the transmission of dangerous transfectants during clinical reconstruction procedures. Autologous human serum was as effective in stimulating growth of bone-marrow stem cells as fetal bovine serum. Furthermore, medium supplemented with autologous human serum was more effective in promoting motility than medium with fetal bovine serum in all cases. Addition of B-fibroblast growth factor to medium with human serum stimulated growth, but not motility. Our results suggest that autologous human serum may provide sufficient ex vivo expansion of human bone-marrow mesenchymal stem cells possessing multidifferentiation potential and may be better than fetal bovine serum in preserving high motility.

Adolescent↗

PubMed2004

Investigation of color motion using MEG and binocular rivalry stimuli.

Previous psychophysical studies have reported a few hundred millisecond difference in the reaction time (RT) to luminance versus color motion in low speed condition. Electroencephalogram (EEG) studies have reported a small difference between initial responses to luminance and color motion, but a big difference comparable to that reported in psychophysical studies has not been observed. The present study aimed to investigate late responses in low speed condition in order to clarify the difference of RTs between luminance and color motion. In general, measurement of the late responses is difficult because the late responses are weaker than the initial responses. A previous EEG study of binocular rivalry has reported that binocular rivalry stimuli amplify late responses. Therefore, we used binocular rivalry stimuli to measure late responses. Visual evoked fields were recorded with a whole-head MEG system. A rivalry-related field (RRF) was obtained from the subtraction between the rivalry and a control condition. The RRF was measured between 400 to 550 ms after the stimulus onset for each motion. Results of source localizations of RRFs had similar positions for both the luminance and the color motion. No statistically significant difference between the latencies of the two RRFs was found.

Adult↗

PubMed2004

The steady-state force-Ca2+ relationship in intact lobster (Homarus americanus) cardiac muscle.

The heart of the decapod crustacean is activated by regular impulse bursts from the cardiac ganglion. The cardiac pump function depends on ganglionic burst frequency, burst duration, and burst impulse frequency. Here, we activated isolated lobster cardiac ostial muscle (Orbicularis ostii muscle, OOM) by stimulus trains in vitro in order to characterize the response of the contractile apparatus to [Ca2+]i. We employed stimulus trains that generate a steady state between the [Ca2+]i and force in order to estimate the Ca2+ sensitivity of myofilaments. Force and [Ca2+]i transients were simultaneously recorded using a silicon strain gauge and the fluorescence of iontophoretically microinjected fura-2 salt. We examined the effects of tetanus duration (TD), the interval between trains, and 6 microM cyclopiazonic acid, an inhibitor of the SR Ca2+ pump, on the steady-state force-[Ca2+]i relationship. The instantaneous force-[Ca2+]i relationships appeared sigmoidal (EC50 and Hill coefficient, 98.8+/-32.7 nM and 2.47+/-0.20, mean +/- SD, respectively), as did the curves superimposed after 500 ms following the start of stimulation, indicating that the force-[Ca2+]i relationship had reached a steady state at that time. Also, the maximum activated force (Fmax) was estimated using the steady-state force-[Ca2+]i relationship. Prolonged stimulus trains, decreasing the interval between recurrent trains from 5 to 2.5 s, and cyclopiazonic acid each increased the measured EC50 without changing Fmax. The EC50 correlated strongly with averaged [Ca2+]i over time. We conclude that the steady-state force-[Ca2+]i relationships in the OOM indicate cooperation between force generation and Ca2+ binding by the myofilaments. Our data also suggest the existence of a novel Ca2+-dependent mechanism which reduces Ca2+ sensitivity and accelerates relaxation of lobster cardiac muscle myofilaments.

Animals↗

PubMed2003

FDG-PET for preoperative differential diagnosis between benign and malignant soft tissue masses.

OBJECTIVE: To evaluate the standardized uptake value (SUV) of [(18)F]2-deoxy-2-fluoro- d-glucose at positron emission tomography (FDG-PET) for preoperative differential diagnosis between benign and malignant soft tissue masses. DESIGN: One hundred and fourteen soft tissue masses (80 benign, 34 malignant) were examined by FDG-PET prior to tissue diagnosis. The SUVs were calculated and compared between benign and malignant lesions and among different histologic subgroups which included three or more cases. RESULTS: There was a statistically significant difference in SUV between benign (1.80+/-1.42 [SD]) and malignant (4.20+/-3.16) soft tissue masses in total (P<0.0001). However, a considerable overlap in SUV was observed between many benign and malignant lesions. Liposarcomas (2.16+/-1.72) and synovial sarcomas (1.60+/-0.43) did not show significantly higher SUV than any benign lesions. Metastases (4.23+/-2.35) showed no statistically significant difference in SUV as compared with schwannomas (1.75+/-0.84), desmoids (2.77+/-1.32), sarcoidosis (3.62+/-1.53), or giant cell tumors of tendon sheath (GCT of TS; 5.06+/-1.63). Even malignant fibrous histiocytomas (5.37+/-1.40) could not be differentiated from sarcoidosis or GCT of TS, based on the SUV. CONCLUSIONS: A large accumulation of FDG can be observed in both benign and malignant histiocytic, fibroblastic, or neurogenic lesions. SUV at conventional FDG-PET is limited to differentiating benign from malignant soft tissue masses, when all kinds of histologic subtypes are included.

Diagnosis, Differential↗

PubMed2003

Simultaneous voiding cystourethrography and voiding urosonography reveals utility of sonographic diagnosis of vesicoureteral reflux in children.

AIM: To evaluate the diagnostic potential of voiding urosonography (VUS) compared with fluoroscopic voiding cystourethrography (VCUG) under identical conditions and to evaluate potential reasons for false-negative VUS results, particularly regarding bladder concentrations of the US contrast agent, Levovist. METHODS: Fifty-six paediatric patients (M/F 34/22, mean age 2.3 y, age range 1 mo-14 y) underwent simultaneous VUS and VCUG under identical conditions. The bladder was filled by simultaneous administration of Levovist and the X-ray contrast medium, DIP Conray. Levovist concentrations in bladders were calculated using amounts of Levovist injected and total DIP Conray infused when reflux was first observed in either procedure. RESULTS: Sensitivities of VUS and VCUG for detection of vesicoureteral reflux (VUR) were both 86%, assuming that VUR detected by either method represented a true-positive, and no reflux by either method represented a true-negative. Patients under 24-mo of age displayed a better VUS sensitivity, of 94%. Levovist concentrations in bladders ranged from 1.8% to 23%, with older children tending to demonstrate increased bladder capacity and lower concentration. All VUS false-negative units displayed Levovist bladder concentrations of less than 5%. CONCLUSION: The present simultaneous study suggests that: 1) the two techniques demonstrate similar sensitivity for detection of reflux; 2) sustained Levovist bladder concentrations of below 5% may not allow detection of reflux on VUS; and 3) VUS represents a suitable technique, particularly for small children whose bladder capacity is not so large.

Adolescent↗

PubMed2002

Excitation-contraction coupling in cardiac muscle of lobster (Homarus americanus); the role of the sarcolemma and sarcoplasmic reticulum.

The T-tubules and sarcoplasmic reticulum (SR) serving excitation-contraction (EC) coupling in lobster (Homarus americanus) cardiac muscle are similar to those in mammalian myocardium. Tetanic contraction is elicited by a burst of action potentials from the cardiac ganglion. In this study we evaluated the roles of the sarcolemma and SR in EC coupling of the ostial valve muscle (orbicularis ostii m. or OOM) of lobster heart. The OOM was mounted in a bath with saline on a microscope stage; force was measured by strain gauge. [Ca2+]i was measured using iontophoretically micro-injected fura-2 salt. Peak [Ca+]i, peak tetanic force and time to peak [Ca2+]i increased with that of stimulus train duration (TD), to a maximum at a TD of 500 ms. Force increased with [Ca2+]. Cd2+ reduced force by 90%; ryanodine and caffeine reduced tetanic [Ca2+]i transients by 80% and 70%, and force by 90% and 80%, respectively. Ryanodine, caffeine and cyclopiazonic acid slowed the decline of [Ca2+]i and force during relaxation. Relaxation required [Na+]o. The rate of decline of [Ca2+]i appeared to be a sigmoidal function of the [Ca2+]i and increased for any [Ca2+]i with TD. Inactivity slowed relaxation of force; stimulation accelerated relaxation. These data suggest important contributions of Ca2+ transport both across the sarcolemma and across the SR membrane during EC-coupling of lobster cardiac muscle, while average cytosolic [Ca2+]i regulates the rate of [Ca2+]i elimination during relaxation.

Animals↗

PubMed2002

Simultaneous voiding cystourethrography and voiding urosonography: an in vitro and in vivo study.

AIM: To compare the diagnostic accuracy of fluoroscopic voiding cystourethrography (VCUG) and voiding urosonography (VUS) under identical conditions. We performed VUS and VCUG simultaneously with the total time for both examinations taking no longer than the time required for either examination individually. MATERIALS AND METHODS: X-ray contrast medium and echo-contrast agent were mixed together in vitro, and echogenicity of the mixture was confirmed. A clinical study was then performed on 33 children who had a history of urinary tract infection. The bladder was filled using simultaneous administration of X-ray contrast medium and echo-contrast agent. VCUG and VUS were then performed simultaneously and evaluated separately by two specialists. RESULTS: Equivalent results were obtained for the two examinations in 61 of 66 renal tracts. Sensitivities of VUS and VCUG for the detection of VUR were 86% and 79%, respectively. The average time from catheterization to the completion of the study was 9.1 minutes - approximately as long as performing VCUG alone. CONCLUSIONS: First, the present simultaneous study is superior to previous comparisons, because the two examinations were performed under identical physiologic conditions. Second, our results suggest that the two techniques demonstrate similar sensitivity in the detection of reflux.

Child↗

PubMed2001

Intervention for prevention of low back pain in Japanese forklift workers.

BACKGROUND: The effectiveness of two different approaches for the prevention of low back pain (LBP) was compared in forklift workers. The first approach (personal) consisted of providing lumbar support, arctic jacket and physical exercise, and the second (facility approach) included the improvement of forklift seats and tires. METHODS: The self-reported prevalence of LBP was surveyed three times before and after the two forms of interventions, in 260 male blue-collar workers including 27 forklift workers, and 55 male white-collar workers of a copper smelter. RESULTS: The initial prevalence of LBP was 63% in the forklift workers, which was significantly higher than that found in the other blue-collar workers (32%) and in the white-collar workers (22%). One year after the first intervention (personal approach) to the forklift workers, the prevalence of LBP fell to 56%. The second intervention (facility approach), which was mainly comprised of a reduction in whole body vibration, was subsequently added, and 9 months later the prevalence of LBP in the forklift workers further decreased to 33%. The reduction of the prevalence from the initial survey was significant (P = 0.008), and that from the second survey was nearly significant (P = 0.070). CONCLUSIONS: These findings suggest that the facility approach is more effective for a reduction of LBP than the personal approach.

Adolescent↗

PubMed2001

Schwannoma of the extremities: the role of PET in preoperative planning.

The aim of this study was to determine the relative utility of various preoperative diagnostic imaging modalities for the evaluation of benign schwannoma, including positron emission tomography (PET) utilising fluorine-18 fluoro-2-deoxy-D-glucose (FDG) and fluorine- 18 alpha-methyl tyrosine (FMT). computed tomography (CT), magnetic resonance imaging (MRI) and digital subtraction angiography (DSA). We retrospectively reviewed imaging findings in 22 patients with 25 histopathologically documented benign schwannomas of the extremities. Pre-operative imaging included: FDG-PET (n=22), FMT-PET (n=17), MRI (n=25), CT (n=16) and DSA (n=17). All 22 lesions examined by PET with FDG and/or FMT showed accumulation. The standardised uptake values (SUVs) for FDG-PET for the 22 examined tumours ranged from 0.33 to 3.7, and eight of them (36.4%) were assessed as malignant on the basis of their uptake. The SUVs for FMT ranged from 0.44 to 1.47, and 15 out of the 17 evaluated (88.2%) showed values indicating the tumour to be benign. CT demonstrated variable attenuation and contrast enhancement. MRI signal characteristics were relatively consistent: iso-signal or darker than skeletal muscle on T1-weighted and isosignal or brighter than subcutaneous fat on T2-weighted images. The venous tumour staining depicted on DSA was found to be significantly correlated with FDG accumulation. All tumours but one were treated by surgical enucleation. One tumour suspected to be malignant on the basis of imaging findings was treated with primary wide resection. Although CT, MRI and PET studies are all useful for the detection and localisation of schwannoma, our findings suggest that, among the imaging modalities studied, FMT-PET may be the most reliable technique for the differentiation of benign schwannoma from malignancy.

Adult↗

PubMed2001

Gouty tophus of the patella evaluated by PET imaging.

We report a case of gouty tophus of the patella, a rare lesion, which was evaluated using positron emission tomography (PET). This modality, which uses a combination of an amino-acid analog emitter, L-[3-(18)F]-alpha-methyl tyrosine (FMT), which neglects malignancies, and a glucose analog emitter, (18)F-fluoro-2-deoxy-D-glucose (FDG), which neglects benign lesions, simulating the radiographic findings, may be useful for the preoperative evaluation of gouty tophus occurring in patella partita, including detection, differentiation from malignant tumors, and possible pathogenetic diagnosis.

Gout↗

PubMed2001

Discriminant analysis of prognostic factors for malignant fibrous histiocytoma in soft tissue.

We prospectively followed 32 patients with soft-tissue malignant fibrous histiocytoma (MFH). Parameters were age; sex; tumor size, location, and depth; operative method; chemotherapy; radiotherapy; and histology. Patients with recurrence or metastases due to MFH within 6 months after the initial operation were separated from those without these characteristics by discriminant analysis with statistically significant difference. The order of influential functions was histology, depth of tumor, operative method, and sex. Male patients with deep-seated storiform-pleomorphic type MFH, receiving less comprehensive surgery, had the greatest risk of local recurrence or early metastases. We have to pay particular attention to patients with these factors and perform adequate surgery, because local recurrence and metastases were found to be closely related, and to have a great influence on the prognosis of this disease. Discriminant analysis to separate patients with MFH recurrence or metastases within 6 months after the initial operation from those without these characteristics is worthwhile for prognostic assessment.

Adult↗

PubMed2001

Clonidine immediately after immobilization stress prevents long-lasting locomotion reduction in the rat.

1. Stress-induced behavioral change in the rat has been utilized as an animal model of anxiety disorder. The authors examined the effect of early intervention by noradrenergic inhibition on stress-induced long-lasting locomotion reduction. 2. Clonidine, an alpha2 agonist, was administered immediately after a single session of 8 min immobilization stress in a restraining box, followed by locomotion measurement on day 1, day 7, and day 14 after the stress session. 3. In the saline-treated control group, locomotion on day 1, day 7, and day 14 after the 8 min stress session was significantly reduced to about 80% in comparison with that before the stress. This finding confirmed the previous report that a single stressful event could lead to long-lasting behavioral changes. When clonidine was administered, locomotion reduction was not observed on any post-stress day. 4. The results suggest that early intervention by noradrenergic inhibition to stressful events may have a preventive effect on subsequent behavioral change which may be considered as an animal model of post-traumatic stress disorder.

Adrenergic alpha-Agonists↗

PubMed2001

Contribution of Na+/Ca2+ exchanger to the regulation of myogenic tone in isolated rat small arteries.

The contribution of the Na+/Ca2+ exchanger to the myogenic vascular tone was examined in rat isolated skeletal muscle small arteries (ASK) with pronounced myogenic tone and mesenteric small arteries (AMS) with little myogenic tone. Myogenic tone was assessed by the vascular inner diameter at transmural pressures of 40 and 100 mmHg. To depress the Na+/Ca2+ exchanger, the extracellular Na+ concentration ([Na+]o) was lowered from 143 to 1.2 mM by substituting choline-Cl for NaCl. The ASK developed significant myogenic tone and constricted further in low [Na+]o. Nifedipine (1 microM) reduced both myogenic tone and low [Na+]o-induced contraction. Because the membrane potential of ASK was not changed by low [Na+]o (-35 +/- 2 mV at 143 mM [Na+]o, -37 +/- 3 mV at 1.2 mM [Na+]o), depolarization-induced Ca2+ influx was not a cause of the low [Na+]o-induced contraction. The AMS did not develop significant myogenic tone. Although low [Na+]o also constricted AMS, the magnitude of constriction was significantly weaker than that in ASK (17 +/- 4 vs. 47 +/- 6%, P < 0.01, at 58 mM Na+). With Bay K 8644, AMS developed myogenic tone, and low [Na+]o-induced constriction was significantly increased. In conclusion, Na+/Ca2+ exchanger may play an important role in regulating myogenic tone, likely via mediating Ca2+-extrusion.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed2001

Microvolt T wave alternans in human cardiac hypertrophy: electrical instability and abnormal myocardial arrangement.

INTRODUCTION: Although T wave alternans (TWA) is a promising risk marker for myocardial electrical instability, it remains unclear how the presence of TWA is related to myocardial damage. METHODS AND RESULTS: TWA was measured in 28 patients with hypertrophic cardiomyopathy (HCM), 29 patients with hypertensive left ventricular hypertrophy (HLVH), and 15 normal volunteers using a CH2000 system. The amplitude of TWA (Valt) was measured at the lead with the maximum amplitude. Cardiac biopsy was performed in 12 HCM patients, who were divided into two groups (severe and mild) based on histologic findings of myocardial disarray and fibrosis. TWA was positive (Valt > 1.9 microV) in 61% of HCM and 31% of HLVH, despite a nearly identical left ventricular mass index (176 +/- 65 g/m2 vs 175 +/- 39 g/m2). Valt at heart rate = 110 beats/min was significantly greater in HCM with severe disarray and fibrosis than in HCM with mild disarray and in HLVH. CONCLUSION: In HCM patients, a positive TWA test probably is related to abnormal myocardial arrangement (disarray) and/or fibrosis, and it may reflect electrical instability of the myocardium.

Aged↗

PubMed2001

The natural history of disappearing bone tumours and tumour-like conditions.

We describe 27 cases of bone tumours or tumour-like lesions where there was spontaneous regression. The follow-up period was 2.8-16.7 years (average, 7.0 years). Fourteen of these cases were no longer visible on plain radiographs. Histological diagnosis included exostosis, eosinophilic granuloma, fibrous dysplasia, fibrous cortical defect, non-ossifying fibroma, osteoid osteoma and bone island. Most cases began to reduce in adolescence or earlier, although sclerotic type lesions showed their regression in older patients. All lesions thought to be eosinophilic granuloma began to regress after periods of less than 3 months, while the duration of the other lesions showed wide variation (1-74 months). As resolution of the lesions took between 2 and 79 months (mean, 25.0 +/- 20.3 months) we consider that the most likely mechanism was recovery of normal skeletal growth control. In exostosis with fracture, alteration of vascular supply may contribute to growth arrest, but not to subsequent remodelling stage. In inflammatory-related lesions such as eosinophilic granuloma, cessation of inflammation may be the mechanism of growth arrest, whilst temporary inflammation may stimulate osteogenic cells engaged in remodeling. In the sclerotic type, growth arrest is a less probable mechanism. Necrosis within the tumour and/or local changes in hormonal control, plus remodelling of the sclerotic area takes longer. Knowledge of the potential for spontaneous resolution may help in management of these tumour and tumour-like lesions of bone.

Adolescent↗