Biomedical subjects

K Shinomiya

Publications and source records attributed to K Shinomiya.

At least 19 recordsLinked to original sources

PubMed2006

ED-71, a novel vitamin D analog, promotes bone formation and angiogenesis and inhibits bone resorption after bone marrow ablation.

ED-71, a novel analog of 1alpha,25-(OH)2 D3, increases bone mass to a greater extent than alfacalcidol, an 1alpha,25-(OH)2 D3 prodrug. In this study, we used a murine bone marrow ablation model to compare the effect of ED-71 on bone formation and resorption in vivo with that of 1alpha,25-(OH)2 D3. We discovered that bone matrix remodeling occurring within the first week after bone marrow ablation was enhanced by a single injection of ED-71, but not by 1alpha,25-(OH)2 D3. This enhancement was associated with an increase in bone surface. Trabecular bone resorption occurring from 1 to 2 weeks after the procedure was suppressed by a single injection of ED-71, but not 1alpha,25-(OH)2 D3, with treated mice exhibiting a reduction in osteoclast numbers, despite increases in osteoblast surface. As seen with the single injection, daily administration of ED-71 also enhanced bone modeling. Bone marrow osteoblast differentiation was also augmented by ED-71 pretreatment. Furthermore, ED-71 treatment immediately after bone marrow ablation enhanced angiogenesis within the bone marrow cavity via enhancement of VEGF(120) expression. In this paper, we clearly demonstrate that ED-71 is an orally administered small molecular weight compound with an anabolic effect on bone metabolism.

Animals↗

PubMed2006

Plasminogen activator inhibitor-1 aids nerve growth factor-induced differentiation and survival of pheochromocytoma cells by activating both the extracellular signal-regulated kinase and c-Jun pathways.

Astrocytes are thought to be critical to neurons' surviving damage caused by ischemic stroke or other injury. Plasminogen activator inhibitor-1 is one of the active soluble factors released by astrocytes and regulates plasminogen activator-plasmin proteolytic sequence in the CNS as a serpin. In this study, we show that plasminogen activator inhibitor-1 can promote neurite outgrowth and survival of rat pheochromocytoma cells in serum-deprived conditions, and that this neuroprotective activity is correlated with enhanced activation of both extracellular signal-regulated kinases following a direct phosphorylation of nerve growth factor receptor, Trk A, and of c-Jun. Our results suggest that plasminogen activator inhibitor-1 can act as a neurotrophic factor, protecting neurons from serum deprivation-induced neuron death not only by compensating for nerve growth factor functions, but also by activating the c-Jun/activating protein-1 pathway.

Animals↗

PubMed2006

Effect of electrical polarization of hydroxyapatite ceramics on new bone formation.

Large surface charges can be induced on hydroxyapatite (HAp) ceramics by proton transport polarization, but this does not affect beta-tricalcium phosphate (TCP) because of its low polarizability. We wished to examine differences in osteogenic cell activity and new bone growth between positively or negatively surface-charged HAp and HAp/TCP plates using a calvarial bone defect model. In the first group of rats, test pieces were placed with their positively charged surfaces face down on the dura mater. In the second group, test pieces were placed with their negatively charged surfaces face down on the dura mater. A third group received noncharged test pieces. Histological examination, including enzymatic staining for osteoblasts and osteoclasts, was carried out. While no bone formation was observed at the pericranium, direct bone formation on the cranial bone debris and new bone growth expanded from the margins of the sites of injury to bridge across both the positively and negatively charged surfaces of HAp and HAp/TCP plates occurred. Electrical polarization of implanted plates, including positive charge, led to enhanced osteoblast activity, though decreased osteoclast activity was seen on the positively charged plate surface. Thus, polarization of HAp ceramics may modulate new bone formation and resorption.

Animals↗

PubMed2005

The lower lumbar spine moment and the axial rotational motion of a body during one-handed and double-handed backhand stroke in tennis.

To analyze the load on the lumbar spine and the motion pattern of a body during a backhand stroke when playing tennis, kinematic and kinetic data of eleven amateur tennis players were collected. Each subject performed one-handed and double-handed strokes at low, medium, and high racket speeds. The three-dimensional motion of the strokes was optically measured by tracking markers attached to their body segments. Floor reaction forces were measured for the right and left feet separately. Using the body motion and the floor reaction force data, the lower lumbar spine moment was calculated based on a segment-link model. Peak and plateau values of the joint moment before and after ball impact were analyzed statistically using a factorial ANOVA (stroke, racket speed). Similarly, the axial rotation angle of the pelvis against the feet and that of the shoulder against the pelvis were analyzed. In all the moments except the lateral bending moment before ball impact and all the rotation angles, there were significant main effects of racket speed. The one-handed strokes showed significantly smaller extension moment before ball impact as well as smaller lateral bending and axial rotation moments after ball impact than the double-handed strokes. The one-handed strokes also showed a significantly smaller axial rotation angle of the shoulder against the pelvis and that of the pelvis against the feet. These results indicate that during one-handed strokes the shoulder and elbow joints share the rotational motion necessary for backhand strokes and consequently reduce the maximal moments imposed on the spinal joints.

Adult↗

PubMed2005

Effect of paroxetine on marble-burying behavior in mice.

The present study was undertaken to investigate the effect of paroxetine, a selective serotonin reuptake inhibitor (SSRI), on marble-burying behavior in mice in comparison with those of fluvoxamine and clomipramine. Marble-burying test is extensively used as an animal model for obsessive/compulsive disorder. A significant inhibition in marble-burying behavior was observed with paroxetine, at a dose of 10 mg/kg. The earlier SSRI, fluvoxamine, also significantly inhibited marble-burying behavior at a dose of 30 mg/kg. Although clomipramine, a tricyclic antidepressant, caused an inhibition in marble-burying behavior, a high dose of 100 mg/kg was needed to show a significant effect. On the other hand, all the drugs used in the present study showed no significant changes in spontaneous locomotor activity at doses inhibiting marble-burying behavior. In conclusion, it was confirmed that paroxetine has a potent inhibitory effect on marble-burying behavior in mice, and could have a similar antiobsessive/anticompulsive activity in human beings.

Animals↗

PubMed2004

Vestibular projection to the periarcuate cortex in the monkey.

Vestibular inputs to the cerebral cortex are important for spatial orientation, body equilibrium, and head and eye movements. We examined vestibular input to the periarcuate cortex in the Japanese monkey by analyzing laminar field potentials evoked by electrical stimulation of the vestibular nerve. Laminar field potential analysis in the depths of the cerebral cortex showed that vestibular-evoked potentials consisted of early-positive and late-negative potentials and early-negative and late-positive potentials in the superficial and deep layers of the periarcuate cortex, respectively, with latencies of 4.8-6.3 ms, suggesting that these potentials were directly conveyed to the cortex through the thalamus. These potentials were distributed continuously in the fundus, dorsal and ventral banks of the spur and the bottom of the junctional part of the arcuate sulcus and spur. This vestibular-projecting area overlapped the cortical distribution of corticovestibular neurons that were retrogradely labeled by tracer injection into the vestibular nuclei (previously reported area 6 pa), and also the distribution of smooth pursuit-related neurons recorded in the periarcuate cortex including area 8 in a trained monkey. These results are discussed in relation to the function of vestibular information in control of smooth pursuit and efferents of the smooth pursuit-related frontal eye field.

Afferent Pathways↗

PubMed2003

Bone morphogenetic protein-2 enhances osterix gene expression in chondrocytes.

Osterix is a recently identified zinc-finger-containing transcription factor, which is required for skeletogenesis as no bone formation was observed in osterix-deficient mice. Osterix was first cloned as a gene whose expression was enhanced by BMP in C2C12 cells. As BMP induces ectopic bone formation in vivo via a pathway reminiscent to endochondral bone formation, BMP may also regulate osterix gene expression in chondrocytes. However, no information was available regarding the BMP actions on osterix gene expression in chondrocytes. We therefore examined the effects of BMP-2 on osterix gene expression in chondrocytes in culture. RT-PCR analysis indicated that osterix mRNA was expressed in the primary cultures of chondrocytes derived from mouse rib cartilage. The treatment with BMP-2 enhanced the levels of osterix transcripts within 24 h and the enhancement was still observed at 48 h based on RT-PCR analysis. This BMP effect was specific to this cytokine, as TGF-beta did not alter osterix gene expression. BMP effects on the osterix mRNA levels were also confirmed by Northern blot analysis. The enhancing effect of BMP on osterix gene expression was observed in a dose-dependent manner starting at 200 ng/ml. The BMP enhancement of the osterix gene expression in chondrocytes was blocked in the presence of a protein synthesis inhibitor, cycloheximide, while it was still observed in the presence of 5,6-dichloro-1-beta D-ribofuranosylbenzimidazol (DRB) suggesting the involvement of post-transcriptional events, which require new protein synthesis. These results indicated that osterix gene is expressed in the primary cultures of chondrocytes and its expression is under the control of BMP-2.

Animals↗

PubMed2003

Effects of [Arg8]-vasopressin on regional cerebral blood flow in spontaneously hypertensive rats.

The effects of [Arg(8)]-vasopressin (AVP) and related compounds on regional cerebral blood flow (rCBF) in the hippocampus were studied using conscious spontaneously hypertensive rats (SHR). rCBF in the hippocampus decreased gradually with age in proportion to an increase in mean blood pressure. Subcutaneous injection of AVP caused a dose-dependent increase in rCBF in the hippocampus. The effects of the metabolic fragments AVP4-9 and AVP4-8 on rCBF were relatively weak. OPC-31260, a vasopressin V(2) antagonist, antagonized the AVP-induced increase in rCBF in the hippocampus. Furthermore, subcutaneous injection of DDAVP, a V(2) agonist, increased rCBF in the hippocampus. On the other hand, the AVP-induced increase in rCBF in the hippocampus was not antagonized by OPC-21268, a vasopressin V(1) antagonist. Intracerebroventricular injection of AVP caused no significant changes in rCBF in the hippocampus, even at a dose of 10 ng/site.

Animals↗

PubMed2001

Establishment and characterization of a cell line from a malignant fibrous histiocytoma of bone developing in a patient with multiple fibrous dysplasia.

PURPOSE AND METHODS: In order to provide material for genetic analysis of fibrous dysplasia (FD), a cell line designated GBS-1 was established from a secondary bone malignant fibrous histiocytoma (MFH) developing in a rib of a 44-year-old male polyostotic FD patient. RESULTS: The GBS-1 cells are characterized by a pleomorphic spindle cell morphology with abundant mucus production. On transplantation to nude mouse subcutis the cell line forms myxoid-spindle cell sarcomas with giant cells, the myxoid product being positive for periodic acid-Schiff (PAS) and alcian blue (Al-B) stains and completely digested by hyaluronidase, mimicking the original tumor. Chromosome and genetic analyses revealed multiple structural and numerical abnormalities of chromosomes with a large number of unidentifiable chromosomes and p53 mutation in exon 7 with LOH in the counterpart. CONCLUSIONS: Since cell lines for FD have hitherto not been available, the GBS-1 cells should prove useful for genetic analyses of FD and also MFH of bone origin.

Adult↗

PubMed2001

Separation of chondroitin sulfate and hyaluronic acid fragments by centrifugal precipitation chromatography.

Centrifugal precipitation chromatography (CPC) was applied for the first time to the separation of fragments of chondroitin sulfate (ChS) and hyaluronic acid (HA). The separation was performed using a gradient elution system between ethanol and water since solubility of these biopolymers highly depends on the concentration of ethanol in aqueous solution. ChS and HA were each eluted into several peaks through a flow-through UV detector at 275 nm, despite they have almost no absorbance at this wavelength in an aqueous solution. The separation was also confirmed by redissolving the dried fraction in water and measuring the absorbance at 210 nm. These results suggest that the CPC system can detect small precipitates of these biopolymers by light scattering at 275 nm. The separated fragments of biopolymers are not easily characterized because no suitable analytical method is available for identification of these compounds. However, the overall results demonstrate that CPC may be a useful separation of biopolymers such as glycosaminoglycans which quantitatively produce precipitates in an organic solvent mixture.

Centrifugation↗

PubMed2001

Functional recovery and regeneration of descending tracts in rats after spinal cord transection in infancy.

STUDY DESIGN: The functional recovery of rats that underwent spinal cord transection in infancy was evaluated by multimodal examination (functional tests, electrophysiologic evaluation, tract-tracing) to determine the basis for the recovery. OBJECTIVES: To determine whether the hind limb function in rats that underwent spinal cord transection in infancy is regained completely, which descending tracts regenerate after the transection, and whether the functional recovery is correlated with axonal reconnection. SUMMARY OF BACKGROUND DATA: It is widely accepted that a newborn rat recovers its hind limb function after spinal cord transection even without any specific treatments. This functional recovery might be attributed to possible regeneration of some descending pathways, although there is a counterargument that well-trained spinal cord reflexes may bring about functional compensation. METHODS: The thoracic spinal cord of infant rats was completely transected at Th10 when they were 2 weeks of age. Multimodal functional tests and electrophysiologic studies were performed 5 weeks later. Some recovered rats (i.e., those able to walk after the transection) underwent spinal cord retransection, with subsequent reevaluation of locomotion and muscle-evoked potentials. At 6 weeks after the initial transection, tract-tracing studies were performed in some animals. RESULTS: A motor performance score detected the functional differences between the control and the recovered rats. Muscle-evoked potentials of hind limbs after electrical stimulation to the brain were recorded in some of the recovered rats, but never in the unrecovered rats. Moreover, the muscle-evoked potentials of the recovered rats disappeared after spinal cord retransection that resulted in loss of voluntary movement. Morphologic studies in two rats provided evidence that reconnection of rubrospinal, vestibulospinal, and reticulospinal tracts had occurred, whereas corticospinal regeneration was not detected. CONCLUSIONS: It can be concluded that the hind limb function of rats that underwent spinal cord transection in infancy was partially regained; that axonal regeneration of the rubrospinal, vestibulospinal, or reticulospinal tracts was demonstrated, whereas the reconnection of the corticospinal tract was not observed; and that the axonal regeneration of these tracts is involved in the functional recovery.

Animals↗

PubMed2001

The biocompatibility and osteoconductive activity of a novel hydroxyapatite/collagen composite biomaterial, and its function as a carrier of rhBMP-2.

A hydroxyapatite/type I collagen (HAp/Col) composite, in which the hydroxyapatite nanocrystals align along the collagen molecules, has been prepared. The biocompatibility, osteoconductive activity, and efficacy as a carrier of recombinant human bone morphogenetic proteins (rhBMPs) of this novel biomaterial were examined. The composite material was implanted in the backs of Wistar rats, and specimens were collected for histological observations until week 24. In a second experiment, other samples of the composite material (5 x 5 x 10 mm3) were drilled and immersed in a solution of rhBMP-2 (0, 200, 400 microg/mL), and subsequently grafted in radii and ulnae in beagle dogs. As a control, three unfilled holes were left in one radius and ulna. X-ray images were prepared, and specimens collected for histological observation at weeks 8 and 12. Histological findings of the composites grafted in rats showed that the surface of the material was eroded as a result of macrophage infiltration. X-ray images and histological findings for the composites implanted in dogs support the idea that HAp/ Col has a high osteoconductive activity and is able to induce bone-remodeling units. In cases where the implants are grafted at weight bearing sites, treatment with rhBMP-2 at a dose of 400 microg/mL may be useful to shorten the time needed until bone union has occurred.

Animals↗

PubMed2001

Long-term results of the anterior floating method for cervical myelopathy caused by ossification of the posterior longitudinal ligament.

STUDY DESIGN: Results of the anterior floating method used to decompress ossification of the posterior longitudinal ligament were studied for an average postoperative interval of 13 years. OBJECTIVE: To investigate the long-term results of the anterior floating method used to manage ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: The anterior floating method is a technique that differs from the extirpation method used to manage ossification of the posterior longitudinal ligament. Reports of the long-term results from anterior decompression used to manage cervical ossification of the posterior longitudinal ligament are rare. METHODS: The anterior floating method was used to decompress cervical ossification of the posterior longitudinal ligament in 63 patients. These patients were followed for more than 10 years with neurologic evaluations using a scoring system proposed by the Japanese Orthopedic Association (JOA score). RESULTS: The recovery rate was 66.5% at 10 years and 59.3% at 13 years, the time of the final survey. Operative outcomes most closely reflected the preoperative duration and severity of myelopathy (JOA score) and the preoperative cross-sectional area of the spinal cord. There was no correlation with the canal narrowing ratio or the thickness of ossification of the posterior longitudinal ligament. Delayed deterioration was attributed to an original inadequate decompression and progression of ossification of the posterior longitudinal ligament outside the original operative field. There was no evidence of significant recurrent ossification of the posterior longitudinal ligament within the margins of prior decompression. CONCLUSIONS: The anterior floating method appears to yield adequate long-term outcomes when used to manage ossification of the posterior longitudinal ligament.

Adult↗

PubMed2001

A new continuous-flow cell separation method based on cell density: principle, apparatus, and preliminary application to separation of human buffy coat.

With the recent progress in transfusion medicine, separation and isolation of cells in a large quantity is becoming increasingly important. At present, the continuous cell separation method in a preparative scale is limited to apheresis and elutriation: the former is mainly used for collection of platelet and buffy coat from the whole blood, while the latter separates cells virtually according to their size. Here we introduce a continuous flow method that separates cells entirely based on cell density. The method is gentle and capable of processing a large number of cells. The potential capability of the method was demonstrated on separation of lymphocytes and granulocytes from human buffy coat. Lymphocytes were enriched to 90% in the fraction at density = 1.065 and granulocytes are isolated in fractions at density = 1.075-1.080 while red cells were completely retained at the periphery of the channel. CD34 cells were distributed around 1.065 and coeluted with lymphocytes, suggesting that further enrichment requires focusing the density gradient around 1.070. The method could process 10(9) nucleated cells in 2 hours. Our preliminary results suggest that the present method is an effective and efficient means to separate blood cells.

Blood Cell Count↗

PubMed2001

Transcriptional suppression of Sox9 expression in chondrocytes by retinoic acid.

SOX9 is a transcription factor that is expressed in chondrocytes and regulates expression of chondrocyte phenotype related genes. Expression of these genes is known to be suppressed by retinoic acid (RA). We, therefore, examined whether the Sox9 gene expression is regulated by RA in chondrocytes. RA treatment suppressed Sox9 mRNA expression in primary chondrocytes prepared from newborn mouse rib cartilage within 12 h and this suppression lasted at least up to 24 h. The RA suppression of Sox9 mRNA levels was dose-dependent starting at 0.5 microM with a maximum at 1 microM. Nuclear run-on assays revealed that RA reduced the rate of transcription of Sox9 gene. Finally, Western blot analysis indicated that RA suppressed SOX9 protein levels in these chondrocytes. Furthermore, overexpression of SOX9 reversed RA suppression of Col2a1 enhancer activity. These observations indicate that RA suppresses Sox9 gene expression in chondrocytes at least in part through transcriptional events. J. Cell. Biochem. Suppl. 36: 71-78, 2001.

Animals↗

PubMed2001

Self-organization mechanism in a bone-like hydroxyapatite/collagen nanocomposite synthesized in vitro and its biological reaction in vivo.

When bone is lost due to injury and/or illness, the defects are generally filled with natural bone because artificial bone materials have problems of bioaffinity. However, natural bone also has supply and infection problems. If an artificial material has the same biological properties as bone, it can replace natural bone for grafting. We synthesized a hydroxyapaite (HAp) and collagen (Col) composite by a simultaneous titration coprecipitation method using Ca(OH)2, H3PO4 and porcine atelocollagen as starting materials. The composite obtained showed a self-organized nanostructure similar to bone assembled by the chemical interaction between HAp and Col. The consolidated composite by a cold isostatic pressure of 200 MPa indicated a quarter of the mechanical strength of bone. It also indicated the same biological properties as grafted bone: The material was resorbed by phagocytosis of osteoclast-like cells and conducted osteoblasts to form new bone in the surrounding area. This HAp/Col composite having similar nanostructure and composition can replace autologous bone grafts.

Animals↗

PubMed2001

Association of plasma adrenomedullin with carotid atherosclerosis in chronic ischemic stroke.

Adrenomedullin is a potent vasodilator peptide exerting anti-atherosclerotic actions in vitro. We investigated the impact of the severity of atherosclerosis on plasma mature-adrenomedullin (m-AM) levels in 38 patients with chronic ischemic stroke. The variables of carotid artery atherosclerosis assessed using ultrasound measurement, blood pressure, and risk factors were related to m-AM levels. Severe atherosclerosis was associated with a further elevation of the increased m-AM level in patients with high systolic blood pressure. Even in patients with fewer risk factors, the presence of severe atherosclerosis was associated with an increased m-AM level. Thus, atherosclerosis elevates m-AM independent of the blood pressure level or presence of risk factors.

Adrenomedullin↗

PubMed2001

Enhancement of bone ingrowth in a titanium fiber mesh implant by rhBMP-2 and hyaluronic acid.

The present study was designed to evaluate the efficacy of high molecular weight hyaluronic acid (HA) used as a carrier of recombinant human bone morphogenetic protein-2 (rhBMP-2) adsorbed to a titanium fiber mesh implant (TFMI) in vivo. The quantity of HA in the TFMI rapidly decreased during the initial 3-day period after implantation. BMP particles were trapped by the meshwork of HA as observed by scanning electron microscopy (SEM). TFMIs containing LF-6, HA, rhBMP-2, or HA combined with rhBMP-2 were implanted on the cranium of rats. Analysis of digitized SEM images of samples obtained six weeks post-implantation was performed to determine the area occupied by new bone. The area fraction of Ca relative to that of the pores of TFMI in the HA group was larger than that in the Ti group (p<0.05). The area fraction of Ca in both the BMP and HA+BMP groups was larger than that in both the Ti and HA groups (p<0.01), and that in the HA+BMP group was larger than that in the BMP group (p<0.05). It is suggested that HA is not only an effective carrier of BMP, but also it may have a positive effect on the generation of new bone in the TFMI.

Journal Article↗