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Biomedical subjects

Y Nishida

Publications and source records attributed to Y Nishida.

At least 19 recordsLinked to original sources
PubMed2006

Acute effect of oral phosphate loading on serum fibroblast growth factor 23 levels in healthy men.

Serum fibroblast growth factor 23 (FGF23) is a novel phosphaturic factor and important for the regulation of inorganic phosphate (Pi) homeostasis. In this study, we examined an acute effect of oral Pi loading on serum FGF23 levels to clarify the role in rapid adjustment of serum Pi level. We performed a randomized, double-blind, crossover study in eight healthy male volunteers. The subjects were alternately served one of three test meals containing different Pi amounts (400 mg (P400), 800 mg (P800), and 1200 mg (P1200)) as lunch at noon. The postprandial changes in serum levels of Pi, Ca, 1,25-dihydroxyvitamin D, intact-parathyroid hormone (iPTH), intact-FGF23 (iFGF23), and urinary excretion of Pi and Ca until 8 h after Pi loading were estimated. Serum Pi levels and urinary Pi excretion significantly increased within 1 h after P400 and P800 intake. Serum iPTH levels at 1-2 and 4-6 h after P1200 intake was significantly higher than those of P400 intake. Serum iFGF23 levels slightly decreased up to 8 h after P400 intake and up to 6 h after P800 intake, but not changed in P1200 intake. Significant increase of iFGF23 was observed at 8 h after P1200 intake compared with both P400 and P800 intake. Additionally, negative association was detected between iFGF23 and serum Pi, whereas positive association was observed between iPTH and serum Pi during the short period. We conclude that oral Pi loading cannot rapidly increase serum FGF23 level. FGF23 may be not associated with rapid adaptation of Pi homeostasis.

Administration, Oral↗
PubMed2005

Use of real-time magnetic resonance image guidance in endoscopic sinus surgery.

We evaluated the effectiveness of magnetic resonance image (MRI) guidance using an optical tracking system (MRI-guided therapy: MRT) in performing endoscopic sinus surgery (ESS). The profiles of the fourteen patients in the present study were as follows: eleven with mucocele in the paranasal sinus, one with recurrent chronic sinusitis, one with maxillary cancer, and one with Graves' ophthalmopathy. Preparation of the MRT system required an additional 54 min in cases involving general anesthesia, and an additional 17 min in cases involving local anesthesia, in comparison with corresponding control groups undergoing ESS in a traditional operating room. We developed nonmetal probes that were visualized in a real-time mode and assistive devices for the optical tracking system that were equipped to avoid obstruction caused by surgical instruments as well as by the hands of surgeons. Using these unique devices, anatomic landmarks were visualized using the present MRT system. The prognosis of patients was favorable, and in particular, no patients with sinus mucocele showed a recurrence of their lesions. We concluded that the MRT system used here for performing ESS was beneficial, especially in terms of the intranasal marsupialization of sinus mucoceles and for the verification of orbital contents.

Journal Article↗
PubMed2004

Propagation characteristics and guiding of a high-power microwave in plasma waveguide.

The propagation characteristics of a high-power microwave [electromagnetic (em) wave] in a plasma waveguide are reported. The plasma waveguide is formed by expanding plasmas via the ponderomotive force of the high-power microwave and the microwave pulse remains trapped within the plasma waveguide and is guided in it. With the increase of the incident microwave power, the width of the plasma waveguide increases and the half width of the radial electric field distribution decreases. This shows that the em wave modifies the refractive index of the plasma waveguide area. For a plasma waveguide with narrower width, the microwave propagates along the plasma waveguide at the fundamental TE mode, while as the waveguide width increases the higher mode component starts appearing. Analytical treatment to the propagation of the electromagnetic wave in a dielectric waveguide having a step-index profile and the numerical calculations for the radial distribution of the electric field show fairly good agreement with the results observed in the present experiments.

Journal Article↗
PubMed2004

Magnetic resonance spectroscopic determination of a neuronal and axonal marker in white matter predicts reversibility of deficits in secondary normal pressure hydrocephalus.

BACKGROUND: Normal pressure hydrocephalus (NPH) is considered to be a treatable form of dementia, because cerebrospinal fluid (CSF) shunting can lessen symptoms. However, neuroimaging has failed to predict when shunting will be effective. OBJECTIVE: To investigate whether 1H (proton) magnetic resonance (MR) spectroscopy could predict functional outcome in patients after shunting. METHODS: Neurological state including Hasegawa's dementia scale, gait, continence, and the modified Rankin scale were evaluated in 21 patients with secondary NPH who underwent ventriculo-peritoneal shunting. Outcomes were measured postoperatively at one and 12 months and were classified as excellent, fair, or poor. MR spectra were obtained from left hemispheric white matter. RESULTS: Significant preoperative differences in N-acetyl aspartate (NAA)/creatine (Cr) and NAA/choline (Cho) were noted between patients with excellent and poor outcome at one month (p = 0.0014 and 0.0036, respectively). Multiple regression analysis linked higher preoperative NAA/Cr ratio, gait score, and modified Rankin scale to better one month outcome. Predictive value, sensitivity, and specificity for excellent outcome following shunting were 95.2%, 100%, and 87.5%. Multiple regression analysis indicated that NAA/Cho had the best predictive value for one year outcome (p = 0.0032); predictive value, sensitivity, and specificity were 89.5%, 90.0%, and 88.9%. CONCLUSIONS: MR spectroscopy predicted long term post-shunting outcomes in patients with secondary NPH, and it would be a useful assessment tool before lumbar drainage.

Adult↗
PubMed2003

CSF hypocretin levels in Guillain-Barré syndrome and other inflammatory neuropathies.

CSF hypocretin-1 was measured in 28 Guillain-Barré syndrome (GBS), 12 Miller-Fisher syndrome, 12 chronic inflammatory demyelinating polyneuropathy (CIDP), and 48 control subjects. Seven GBS subjects had undetectably low hypocretin-1 levels (<100 pg/mL). Hypocretin-1 levels were moderately reduced in an additional 11 GBS, 5 Miller-Fisher syndrome, and 1 CIDP subject. Low levels in GBS occurred early in the disease and were associated with upper CNS level abnormalities.

Adolescent↗
PubMed2003

Remodelling and healing process of moderately heat-treated bone grafts after wide resection of bone and soft-tissue tumors.

INTRODUCTION: In the reconstruction of extensive bone defects after massive resection of malignant musculoskeletal tumors, the clinical results of moderately heat-treated autogenous bone graft have rarely been documented. We evaluated the remodelling and healing process of moderately heat-treated autogenous bone graft by means of imaging features. MATERIALS AND METHODS: The subjects of this study were 19 patients with bone and soft-tissue tumors treated by heat-treated bone graft at our institution between 1992 and 2001, the mean follow-up period was 4.8+/-2.8 years (range 1-9 years). The remodelling and healing process of heat-treated bone graft was evaluated by means of radiography, bone scintigraphy, and MRI. RESULTS: The mean period to obtain bone union between host bone and grafted bone was 9.4 months. Infection was noted in 1 patient, and fracture was present in 2 patients. In 6 patients, pseudoarthrosis was found. Bone scintigraphy showed an increased uptake at the host-graft junction in the period between 3 and 36 months (median 10.7 months) postoperatively. A gradually increased diffuse uptake on the grafted side was evident at an average of 29.1 months (range 19-41 months) postoperatively. High signal intensity on T2-weighted images was observed in the early period after surgery, and iso-intense or low signal intensity became evident after an average of 28.3 months. A gradually increased diffuse uptake on scintigraphy and iso-intense or low signal intensity on T2-weighted images indicated remodelling of the grafted bone. CONCLUSION: Bone union of a moderately heat-treated autogenous bone graft was noted at about 9 months, and its remodelling was proceeding at about 30 months. This method will be useful for bone defects after massive resection of soft-tissue and bone tumors.

Adolescent↗
PubMed2003

Stimulated type I collagen turnover in patients with giant cell tumor of bone.

The aim of this study was to determine type I collagen turnover in giant cell tumor of bone (GCT) by biochemical markers of type I procollagen aminoterminal propeptide (PINP) and type I collagen carboxyterminal telopeptide (ICTP) as synthesis and degradation markers, respectively. The serum concentrations of PINP and ICTP were measured in 11 patients with GCT using radioimmunoassay, and analyzed by the correlation to the grades of GCT progression described by Campanacci. Serum of the 11 healthy subjects was available for comparison. The serum concentration of PINP was significantly higher in patients with GCT (82.4 +/- 46.2 ng/ml) than in controls (40.8 +/- 12.1 ng/ml) (P < 0.01), and that of ICTP was also significantly higher in GCT (5.3 +/- 2.0 ng/ml) than in controls (3.2 +/- 0.8 ng/ml) (P < 0.01). In GCT, the PINP concentration of grade 3 (127.6 +/- 38.8 ng/ml) was higher than that in grade 1 patients (46.9 +/- 4.8 ng/ ml) (P < 0.01). ICTP concentration of both grades 2 (7.1 +/- 1.4 ng/ml) and 3 (5.8 +/- 1.8 ng/ml) patients was significantly higher than that of grade 1 (3.5 +/- 0.6 ng/ ml) patients (P < 0.01, P < 0.05, respectively). Two cases of serum concentration of PINP and ICTP after resection of GCT demonstrated that these biomarkers decreased to the control levels in the absence of GCT. Our results indicated that type I collagen turnover evaluated by ICTP and PINP was stimulated in the presence of GCT. Moreover, this enhanced metabolic turnover reflects the grade of GCT.

Adult↗
PubMed2003

Telomerase, p53 and PCNA activity in osteosarcoma.

AIMS: The aim of this study was to investigate telomerase activity and to assess the correlation between telomerase activity, tumor proliferative activity and p53 overexpression in osteosarcoma tumor samples. METHODS: Using a telomerase polymerase chain reaction-enzyme-linked immunoassay based on the telomeric repeat amplification protocol method, we examined telomerase activity in 26 primary osteosarcoma specimens. P53 overexpression was identified using immunohistochemical staining, and tumor proliferative activity was assessed by immunohistochemical staining of PCNA. RESULTS: Telomerase activity was detected at a relatively low level in five of 26 osteosarcoma tissue specimens. P53 was detected in eight of 21 cases. There was no significant correlation between telomerase activity and p53 overexpression (p=0.325). There was a significant correlation between PCNA staining and telomerase activity (p=0.0075). CONCLUSION: Difference between the telomerase activity and p53 overexpression in osteosarcoma suggests that p53 and telomerase may not cooperate in tumor proliferation. Correlation of telomerase activity to PCNA expression suggests that telomerase activity may also useful for evaluate proliferative activity in osteosarcoma.

Adolescent↗
PubMed2003

A study of inter-alpha-trypsin inhibitor chains expression in liposarcomas.

AIM: Liposarcoma is common soft tissue sarcoma that is sometimes difficult to treat, besides its good prognosis. The inter-alpha-trypsin inhibitor heavy chains (HCs) has been reported to be linked to hyaluronan, which play important roles in tumour progression and metastasis. In this study, clinical significance of HCs in patients with liposarcoma was investigated. METHODS: HC expression was studied by immunohistochemistry on resected specimens of 33 liposarcoma patients and 10 lipoma patients. The expression of HC mRNA was analyzed by reverse transcription polymerase chain reaction (RT-PCR). Serum concentration of HC was determined with enzyme-linked immunosorbent assay (ELISA). RESULTS: Prominent positive staining of HC was observed in extracellular matrix of pleomorphic and myxoid liposarcoma. In well-differentiated liposarcoma and lipoma, faint staining was seen with HC. No products of HC could be detected by RT-PCR. Serum concentration of HC was not up-regulated in any subtypes of liposarcoma. HC expression was not significantly correlated with tumour subtypes and prognosis. CONCLUSION: HC was strongly accumulated in pleomorphic and myxoid liposarcoma, however, was not locally synthesized in liposarcoma. HC might play roles in stabilizing extracellular matrix, such as hyaluronan (HA), in liposarcoma.

Alpha-Globulins↗
PubMed2002

Interaction of an electromagnetic wave with a suddenly stopped ionization front.

The theory of the interaction of an electromagnetic wave with a uniformly moving ionization front in a gas is extended to include the case when the front suddenly stops. This nonstationary character of the wave/front interaction, which is typical for experiments carried out in a finite-size gas tube, gives rise to fresh physical effects. First, currents induced near the plasma boundary after the front stops produce a static magnetic field not only in the plasma behind the front but also in the vacuum ahead of the front. Second, in the regime where the transmitted wave falls off behind the front, the skinning field leaks through the stopped front and produces a burst of highly frequency up-shifted radiation.

Journal Article↗
PubMed2002

Investigation of interfacial interaction between uncoated and coated carbon fibres and the magnesium alloy AZ91.

Unidirectionally reinforced metal-matrix composites with a fibre volume content between 63 and 68% were processed by squeeze casting using T800 H carbon fibres and the magnesium alloy AZ91. The surface of the fibres was prepared by thermal desizing of the fibres or by deposition of a pyrolytic carbon (pyC) coating. Different interfacial conditions could be identified by transmission electron microscopy (TEM) and the single-fibre push-in test. TEM confirmed the formation of needle-like phases at the fibre surface or, for coated fibres, within the pyrolytic carbon coating. During loading by the Vickers type indenter an intense response was observed for composites of coated fibres and the magnesium alloy. This could by caused by stick-slip effects within the pyrolytic carbon coating.

Journal Article↗
PubMed2002

Experimental observation of radiation from cherenkov wakes in a magnetized plasma.

A proof-of-principle experiment demonstrates the generation of radiation from the Cherenkov wake excited by an ultrashort- and ultrahigh-power pulse laser in a perpendicularly magnetized plasma. The frequency of the radiation is in the millimeter range (up to 200 GHz). The intensity of the radiation is proportional to the magnetic field intensity as expected by theory. Polarization of the emitted radiation is also detected. The difference in the frequency of the emitted radiation between these experiments and previous theory can be explained by the electrons' oscillation in the electric field of a narrow column of ions in the focal region.

Journal Article↗
PubMed2002

Propagation of short intense laser pulses in gas-filled capillaries.

The guided laser pulse propagation and wake-field generation are studied in a wide (in comparison with the laser spot size) gas-filled capillary with an on-axis gas density depletion, which can be produced by a rapid spin of the capillary around its axis or by radially propagating shock waves generated in a piezoceramic tube. A single equation for the wake-field potential, which describes the fully relativistic plasma response in the presence of optical field ionization (OFI) of a gas, is derived and used to demonstrate a guided propagation of a short intense laser pulse over many Rayleigh lengths in a leaky plasma channel produced by the pulse due to OFI in the capillary filled with a radially inhomogeneous gas. The efficient generation of a regular wake field over long distances suitable for the laser wake-field accelerators is shown.

Journal Article↗
PubMed2001

CSF hypocretin/orexin levels in narcolepsy and other neurological conditions.

OBJECTIVE: To examine the specificity of low CSF hypocretin-1 levels in narcolepsy and explore the potential role of hypocretins in other neurologic disorders. METHODS: A method to measure hypocretin-1 in 100 microL of crude CSF sample was established and validated. CSF hypocretin-1 was measured in 42 narcolepsy patients (ages 16-70 years), 48 healthy controls (ages 22-77 years,) and 235 patients with various other neurologic conditions (ages 0-85 years). RESULTS: As previously reported, CSF hypocretin-1 levels were undetectably low (<100 pg/mL) in 37 of 42 narcolepsy subjects. Hypocretin-1 levels were detectable in all controls (224-653 pg/mL) and all neurologic patients (117-720 pg/mL), with the exception of three patients with Guillain-Barré syndrome (GBS). Hypocretin-1 was within the control range in most neurologic patients tested, including patients with AD, PD, and MS. Low but detectable levels (100-194 pg/mL) were found in a subset of patients with acute lymphocytic leukemia, intracranial tumors, craniocerebral trauma, CNS infections, and GBS. CONCLUSIONS: Undetectable CSF hypocretin-1 levels are highly specific to narcolepsy and rare cases of GBS. Measuring hypocretin-1 levels in the CSF of patients suspected of narcolepsy is a useful diagnostic procedure. Low hypocretin levels are also observed in a large range of neurologic conditions, most strikingly in subjects with head trauma. These alterations may reflect focal lesions in the hypothalamus, destruction of the blood brain barrier, or transient or chronic hypofunction of the hypothalamus. Future research in this area is needed to establish functional significance.

Carrier Proteins↗
PubMed2001

Syntheses and biological evaluations of alpha-D-mannosyl [60]fullerenols.

[60]Fullerenols carrying mono- and bis-alpha-D-mannosyl linkages on the surface were prepared via a [3+2]-cycloaddition reaction between 2-azidoethyl alpha-D-mannoside and C(60) followed by polyhydroxylation with aqueous NaOH. Their biological activity was evaluated in terms of binding affinity to lectins by hemagglutination assay and surface plasmon resonance. [60]Fullerenols without the mannosyl linkage caused aggregation of erythrocytes and binding to a beta-D-galactopyranoside specific lectin (RCA(120)). In contrast, mono- and bis-mannosyl fullerenols were found to decrease the activity for both aggregating erythrocytes and binding to RCA(120), and mono-mannosyl fullerenols turned to binding to alpha-D-mannose specific lectin (Con A).

Carbon↗