Biomedical subjects

Kozo Nakamura

Publications and source records attributed to Kozo Nakamura.

At least 19 recordsLinked to original sources

PubMed2007

Local application of recombinant human fibroblast growth factor-2 on bone repair: a dose-escalation prospective trial on patients with osteotomy.

Based on preclinical evidence in animal models, the present study examined the clinical efficacy and safety of recombinant human fibroblast growth factor-2 (rhFGF-2) to accelerate bone repair in a dose-escalation prospective trial. One of three dosages (200, 400 or 800 microg) of rhFGF-2 in a biodegradable gelatin hydrogel was injected during surgery into the osteotomy site of 59 knee osteoarthritis patients undergoing high tibial osteotomy, and 57 of them were monitored for 16 weeks. The rhFGF-2 dose dependently increased the percentage of patients with radiographic bone union, and decreased the average time needed for such union. The percentages of patients with an absence of pain and full-weight bearing were also greater in the higher dosage groups than in the low dosage group, especially in the clinically critical periods 6, 8, and 10 weeks. Neither blood chemistries nor clinical adverse events were associated with the rhFGF-2 dosages. We therefore conclude that the rhFGF-2 in gelatin hydrogel dose dependently accelerated radiographic bone union of a surgical osteotomy with a safety profile at least at the dosages used, suggesting the clinical efficacy of this agent for bone repair.

Adult↗

PubMed2007

Distraction osteogenesis promotes angiogenesis in the surrounding muscles.

Distraction osteogenesis is used to treat atrophic nonunion and focal osteomyelitis. It enhances blood vessel formation in the distracted callus and in the surrounding soft tissues. Long-term angiogenesis, however, is not well described. We hypothesized newly formed blood vessels persist in the surrounding muscles until the late consolidation period. We performed unilateral tibial lengthening in eight adult Beagles. Seven days after tibial osteotomy, we began lengthening for 30 days, following which consolidation was allowed to proceed for another 60 days. We took bilateral microangiograms of the bilateral tibialis anterior, extensor digitorum longus, and gastrocnemius muscles. We determined the blood vessel volume density and the longitudinal and transverse microangiographic scores. The number of blood vessels in specified diameter ranges was determined histologically. The blood vessel volume density of the distracted limb was higher in all three muscles. The longitudinal microangiographic score was higher for the tibialis anterior and extensor digitorum longus muscles on the distracted side, whereas the transverse microangiographic score was not higher. Histologically, the number of blood vessels less than 100 mum in diameter on the distracted side was higher in the tibialis anterior and extensor digitorum longus muscles. Our data suggest distraction osteogenesis activates angiogenesis and maintains increased vascularity until the late consolidation period.

Angiography↗

PubMed2006

Tailor-made tricalcium phosphate bone implant directly fabricated by a three-dimensional ink-jet printer.

Rapid prototyping (RP) is a molding technique that builds a three-dimensional (3D) model from computer-aided design (CAD) data. We fabricated new tailor-made bone implants (TIs) from alpha-tricalcium phosphate powder using an RP ink-jet printer based on computed tomography (CT) data, and evaluated their safety and efficacy. CT data of the skulls of seven beagle dogs were obtained and converted to CAD data, and bone defects were virtually made in the skull bilaterally. TIs were designed to fit the defects and were fabricated using the 3D ink-jet printer with six horizontal cylindrical holes running through the implants, designed for possible facilitation of vascular invasion and bone regeneration. As a control, hydroxyapatite implants (HIs) were cut manually from porous hydroxyapatite blocks. Then, craniectomy was performed to create real skull defects, and TIs and HIs were implanted. After implantation, CT was performed regularly, and the animals were euthanized at 24 weeks. No major side effects were observed. CT analysis showed narrowing of the cylindrical holes; bony bridging between the implants and the temporal bone was observed only for TIs. Histological analysis revealed substantial new bone formation inside the cylindrical holes in the TIs, while mainly connective tissues invaded the porous structures in HIs. Bone marrow was observed only in TIs. Osteoclasts were seen to resorb regenerated bone from inside the cylindrical holes and to invade and probably resorb the TIs. These data suggest that TIs are a safe and effective bone substitute, possessing osteoconductivity comparable with that of HIs.

Animals↗

PubMed2006

Polyphenolic content and physiological activities of Chinese hawthorn extracts.

Hawthorn polyphenol (HP) was prepared by ethyl acetate treatment of the ethanol extract (HE) of Chinese hawthorn fruit. The concentrations of 15 polyphenols in the HP, HE, extraction residue (HJ), and a hawthorn leaf extract (HF) were determined by HPLC. For HP, the total content of the 15 polyphenols was 21.4%, comprised of 19.7% of procyanidins, 1.21% of chlorogenic acid, and 0.48% of flavonoids, compared to 2.55% for the HE. The yields of procyanidin monomer, dimer, trimer, tetramer, and pentamer were 50.5%, 30.3%, 23.0%, 14.6%, and 12.5% respectively, and the mean degree of polymerization was reduced to 1.39 (HP) from 1.65 (HE). Seven different physiological actions of the four extracts were investigated. The HP showed strong O(2)(-) and (.-)OH scavenging capacities (IC(50) values of 6.3 microg/ml and 1.1 microg/ml respectively), as well as selective prolyl endopeptidase inhibition (IC(50) of 60 microg/ml). The active constituents appeared to be procyanidins.

Antioxidants↗

PubMed2006

Growth factor treatment and genetic manipulation stimulate neurogenesis and oligodendrogenesis by endogenous neural progenitors in the injured adult spinal cord.

Neurons and oligodendrocytes are highly vulnerable to various insults, and their spontaneous replacement occurs to only a limited extent after damage in the adult spinal cord. The environment of injured tissue is thus thought to restrict the regenerative capacity of endogenous neural stem/progenitor cells; strategies for overcoming such restrictions remain to be developed. Here, we combined growth factor treatment and genetic manipulation to stimulate neurogenesis and oligodendrogenesis by endogenous progenitors in vivo. The recombinant retrovirus pMXIG, which was designed to coexpress green fluorescent proteins (GFPs) and a neurogenic/gliogenic transcription factor, was directly injected into the injured spinal cord parenchyma to manipulate proliferative cells in situ. We found that cells expressing Olig2, Nkx2.2, and NG2 were enriched among virus-infected, GFP-positive (GFP+) cells. Moreover, a fraction of GFP+ cells formed neurospheres and differentiated into neurons, astrocytes, and oligodendrocytes in vitro, demonstrating that GFP retroviruses indeed infected endogenous neural progenitors in vivo. Neuronal differentiation of control virus-infected cells did not occur at a detectable level in the injured spinal cord. We found, however, that direct administration of fibroblast growth factor 2 and epidermal growth factor into lesioned tissue could induce a significant fraction of GFP-labeled cells to express immature neuronal markers. Moreover, retrovirus-mediated overexpression of the basic helix-loop-helix transcription factors Neurogenin2 and Mash1, together with growth factor treatment, enhanced the production and maturation of new neurons and oligodendrocytes, respectively. These results demonstrate that endogenous neural progenitors can be manipulated to replace neurons and oligodendrocytes lost to insults in the injured spinal cord.

Animals↗

PubMed2006

Prediction of strength and strain of the proximal femur by a CT-based finite element method.

Hip fractures are the most serious complication of osteoporosis and have been recognized as a major public health problem. In elderly persons, hip fractures occur as a result of increased fragility of the proximal femur due to osteoporosis. It is essential to precisely quantify the strength of the proximal femur in order to estimate the fracture risk and plan preventive interventions. CT-based finite element analysis could possibly achieve precise assessment of the strength of the proximal femur. The purpose of this study was to create a simulation model that could accurately predict the strength and surface strains of the proximal femur using a CT-based finite element method and to verify the accuracy of our model by load testing using fresh frozen cadaver specimens. Eleven right femora were collected. The axial CT scans of the proximal femora were obtained with a calibration phantom, from which the 3D finite element models were constructed. Materially nonlinear finite element analyses were performed. The yield and fracture loads were calculated, while the sites where elements failed and the distributions of the principal strains were determined. The strain gauges were attached to the proximal femoral surfaces. A quasi-static compression test of each femur was conducted. The yield loads, fracture loads and principal strains of the prediction significantly correlated with those measured (r=0.941, 0.979, 0.963). Finite element analysis showed that the solid elements and shell elements in undergoing compressive failure were at the same subcapital region as the experimental fracture site.

Adult↗

PubMed2006

Negative regulation of osteoclastogenesis by ectodomain shedding of receptor activator of NF-kappaB ligand.

Receptor activator of NF-kappaB ligand (RANKL) is a transmembrane glycoprotein that has an essential role in the development of osteoclasts. The extracellular portion of RANKL is cleaved proteolytically to produce soluble RANKL, but definite RANKL sheddase(s) and the physiologic function of RANKL shedding have not yet been determined. In the present study, we found that matrix metalloproteinase (MMP) 14 and a disintegrin and metalloproteinase (ADAM) 10 have strong RANKL shedding activity. In Western blot analysis, soluble RANKL was detected as two different molecular weight products, and RNA interference of MMP14 and ADAM10 resulted in a reduction of both the lower and higher molecular weight products. Suppression of MMP14 in primary osteoblasts increased membrane-bound RANKL and promoted osteoclastogenesis in cocultures with macrophages. Soluble RANKL produced by osteoblasts from MMP14-deficient mice was markedly reduced, and their osteoclastogenic activity was promoted, consistent with the findings of increased osteoclastogenesis in vivo. RANKL shedding is an important process that down-regulates local osteoclastogenesis.

ADAM Proteins↗

PubMed2006

Erk pathways negatively regulate matrix mineralization.

Skeletal mineralization is an important step regulating the mechanical properties of the calcified tissues, but molecular events underlying mineralization still remain elusive. We examined the role of extracellular signal-regulated kinase (Erk) pathways in matrix mineralization of osteogenic cells both in vitro and in vivo. Matrix mineralization by preosteocytic MLO-A5 cells and osteoblastic MC3T3-E1 cells was increased by either PD98059 Mek inhibitor treatment or adenovirus vector-mediated dominant negative Ras (Ras(DN)) expression and was suppressed by Erk activation by platelet-derived growth factor (PDGF) treatment or constitutively active Mek1 (Mek(CA)) expression. Administration of adenovirus vectors carrying Ras(DN) gene onto the calvaria of 1-day-old mice increased the mineralization of the tissues, while that of the Mek(CA) adenovirus suppressed it. These results suggest that the Erk pathway is a negative regulator of the matrix mineralization both in vitro and in vivo.

Actins↗

PubMed2006

Fusionless surgery for scoliosis: 2-17 year radiographic and clinical follow-up.

STUDY DESIGN: Descriptive case series. OBJECTIVE: To determine whether fusionless, multiple vertebral wedge osteotomy can safely obtain correction of the deformity with adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA: To our knowledge, no such attempts to manage the AIS with fusionless, vertebral osteotomies have been reported. METHODS: A total of 20 consecutive patients were treated since 1987. Deformity correction, complications, respiratory function, and patient-oriented outcome were investigated. RESULTS: There were 20 patients (17 females and 3 males), including 19 with idiopathic and 1 with syringomyelia scoliosis, who underwent surgery at an average age of 16.4 years and were followed for 8.9 years (range 2-17) on average. There were no neurologic complications. One superficial wound infection necessitated debridement. There were 2 patients converted to posterior instrumentation surgery because of deterioration of the deformity. The average Cobb angle of 64.0 degrees before surgery was corrected to 48.2 degrees at 8.9 years after surgery. Decline of the pulmonary function test after surgery was not statistically significant. The patients' responses to questions about function and pain were favorable. CONCLUSION: Deformity with AIS was safely corrected with fusionless, multiple vertebral wedge osteotomy.

Adolescent↗

PubMed2006

Regulation of bone formation by adiponectin through autocrine/paracrine and endocrine pathways.

Since interaction between bone and lipid metabolism has been suggested, this study investigated the regulation of bone metabolism by adiponectin, a representative adipokine, by analyzing deficient and overexpressing transgenic mice. We initially confirmed that adiponectin and its receptors were expressed in osteoblastic and osteoclastic cells, indicating that adiponectin can act on bone not only through an endocrine pathway as a hormone secreted from fat tissue, but also through an autocrine/paracrine pathway. There was no abnormality in bone mass or turnover of adiponectin-deficient (Ad-/-) mice, possibly due to an equivalent balance of the two pathways. In the culture of bone marrow cells from the Ad-/- mice, osteogenesis was decreased compared to the wild-type (WT) cell culture, indicating a positive effect of endogenous adiponectin through the autocrine/paracrine pathway. To examine the endocrine action of adiponectin, we analyzed transgenic mice overexpressing adiponectin in the liver, and found no abnormality in the bone. Addition of recombinant adiponectin in cultured osteoprogenitor cells suppressed osteogenesis, suggesting that the direct action of circulating adiponectin was negative for bone formation. In the presence of insulin, however, this suppression was blunted, and adiponectin enhanced the insulin-induced phosphorylations of the main downstream molecule insulin receptor substrate-1 and Akt. These lines of results suggest three distinct adiponectin actions on bone formation: a positive action through the autocrine/paracrine pathway by locally produced adiponectin, a negative action through the direct pathway by circulating adiponectin, and a positive action through the indirect pathway by circulating adiponectin via enhancement of the insulin signaling.

Adiponectin↗

PubMed2006

Nonlinear finite element model predicts vertebral bone strength and fracture site.

STUDY DESIGN: A study on computed tomography (CT)-based finite element (FE) method that predicts vertebral strength and fracture site using human cadaveric specimens. OBJECTIVE: To evaluate the accuracy of the nonlinear FE method by comparing the predicted data with those of mechanical testing. SUMMARY OF BACKGROUND DATA: FE methods may predict vertebral strength and fracture site but the prediction has been difficult because of a complex geometry, elastoplasticity, and thin cortical shell of the vertebra. METHODS: FE models of the 12 thoracolumbar vertebral specimens were constructed. Nonlinear FE analyses were performed, and the yield load, the fracture load, the sites where elements failed, and the distribution of minimum principal strain were evaluated. A quasi-static uniaxial compression test for the same specimens was conducted to verify these analyses. RESULTS: The yield loads, fracture loads, minimum principal strains, and fracture sites of the FE prediction significantly correlated with those measured. CONCLUSIONS: Nonlinear FE model predicted vertebral strength and fracture site accurately.

Adult↗

PubMed2006

Quantification of the polyphenols and triterpene acids in chinese hawthorn fruit by high-performance liquid chromatography.

The levels of seven polyphenols (epicatechin, procyanidin B2, procyanidin B5, procyanidin C1, hyperoside, isoquercitrin, and chlorogenic acid) and two triterpene acids (oleanolic acid and ursolic acid) in the matured fruits of Chinese hawthorn (Crataegus pinnatifida Bge. var. major N.E.Br.) were determined by high-performance liquid chromatography methods. The average contents of those constituents in 37 representative cultivars were 1405, 1505, 339, 684, 56, 41, 234, 952, and 147 microg/g fresh weight (FW), respectively. A significant inverse correlation between the procyanidin contents and the latitude of the geographical origin of the cultivars was observed (r = 0.3851, P < 0.02). Correlation analysis of the levels of the nine compounds in the 37 cultivars yielded a strong correlation (P < 0.001) between the individual levels of the four procyanidins and the sum of the procyanidins level (r = 0.7413-0.9898) and between the flavonoids and the chlorogenic acid (r = 0.5383-0.9212). The changes in level of the nine compounds in the hawthorn fruit were evaluated during maturation using the Hebei Dajinxing cultivar. Sixty-one days after blossom, the polyphenol level reached the highest point and the sum of the contents was 1.36 g/100 g FW.

Chlorogenic Acid↗

PubMed2006

Prognostic factors for patients with spinal metastases from lung cancer.

STUDY DESIGN: We conducted a retrospective study to identify prognostic factors of patients with spinal metastases from lung cancer. OBJECTIVE: To provide clinical data with strong association to the prognosis and to propose criteria determining indication of operation for spinal metastases. SUMMARY OF BACKGROUND DATA: To make a proper selection of patients for whom surgery is indicated, forecasting short-time survival after spinal metastases is very important. In the past, there has been no report of prognostic factors of patients with such metastases from this cancer. METHODS: This study included 114 patients with spinal metastases of lung cancer. Tumors were histologically categorized as non-small cell lung cancer (NSCLC) in 94 patients and small cell lung cancer (SCLC) in 20 patients. We investigated prognostic factors after spinal metastases using Cox comparative hazard model and a preoperative prognostic score proposed by Tokuhashi. We also investigated the patients who underwent operation for spinal metastases from lung cancer in our hospital. RESULTS: Multivariate analysis showed that the significant prognostic factors for survival after spinal metastases from NSCLC were performance status (PS), Ca, Alb. Among SCLC patients, Ca, Alb, and a history of chemotherapy were significant (P < 0.05) in univariate analysis. The score of Tokuhashi was not correlative to the survival period. Among the operated patients, postoperative PS was significant for the period of postoperative survival. CONCLUSION: PS, Ca, and Alb in NSCLC and Ca, Alb, and a history of chemotherapy in SCLC are useful for determining an indication of operation for spinal metastases from lung cancer.

Activities of Daily Living↗

PubMed2006

Neurologic level diagnosis of cervical stenotic myelopathy.

STUDY DESIGN: A cross-sectional analysis. OBJECTIVE: To elucidate the accuracy of neurologic level diagnosis of cervical stenotic myelopathy. SUMMARY OF BACKGROUND DATA: Neurologic level diagnosis in cervical myelopathy has not been well established. METHODS: A total of 106 patients with cervical stenotic myelopathy, with a single-level intramedullary high-intensity area confirmed on both preoperative and postoperative T2-weighted magnetic resonance imaging (MRI), were included in this study. We performed a level diagnosis on the basis of neurologic signs (the uppermost muscle with weakness, diminished or exaggerated deep tendon reflex, the uppermost level of sensory disturbance of the upper extremities) and compared it with a level diagnosis made by T2-weighted MRI. The sensitivity, specificity, and accuracy of neurologic signs on our index corresponding to each intervertebral level were calculated. RESULTS: The averages of sensitivity, specificity, and accuracy were 42%, 80%, and 70%, respectively, in the uppermost muscle with weakness, 66%, 89%, and 83% in deep tendon reflex, and 74%, 91%, and 87% in the sensory disturbance area. The positive and negative predictive values were 40% and 91%, respectively, in the uppermost muscle with weakness, 66% and 89% in deep tendon reflex, and 74% and 91% in the sensory disturbance area. Accuracy of a diagnosis based on muscle weakness was less high, the reason being that in many patients, the uppermost muscle with weakness was extensor digiti communis or the intrinsic muscles of the hands, and this led to a lower sensitivity. CONCLUSIONS: The average accuracy of neurologic level diagnosis based on the index we proposed was > or =70%. The level diagnosis by a sensory disturbance area showed the highest accuracy (87%).

Adult↗

PubMed2006

Carminerin contributes to chondrocyte calcification during endochondral ossification.

Endochondral ossification is an essential process not only for physiological skeletal development and growth, but also for pathological disorders. We recently identified a novel cartilage-specific molecule, carminerin (also known as cystatin 10 and encoded by Cst10), which is upregulated in synchrony with cartilage maturation and stimulates the later differentiation of cultured chondrocytes. Although carminerin-deficient (Cst10-/-) mice developed and grew normally, they had a microscopic decrease in the calcification of hypertrophic chondrocytes at the growth plate. When we created experimental models of pathological endochondral ossification, we observed suppression of chondrocyte calcification during formation of osteoarthritic osteophytes, age-related ectopic ossification and healing of bone fractures in Cst10-/- mice. Cultured Cst10-/- chondrocytes showed a reduction in calcification with activation of an SRY site in the promoter of the gene encoding nucleotide pyrophosphatase phosphodiesterase 1 (NPP1, encoded by Enpp1). Functional NPP1 is required for carminerin deficiency to suppress the pathological endochondral ossifications listed above. Carminerin is the first cartilage-specific protein that contributes to chondrocyte calcification during endochondral ossification under physiological and pathological conditions through the transcriptional inhibition of NPP1.

Animals↗

PubMed2006

A large-scale genetic association study of ossification of the posterior longitudinal ligament of the spine.

Research to date has identified several genes that are implicated in the etiology of ossification of the posterior longitudinal ligament of the spine (OPLL); however, their pathogenetic relevance remains obscure. The aim of this study is to identify susceptibility genes for OPLL through a large-scale case-control association study and to re-examine previously reported associations. A total of 109 single nucleotide polymorphisms (SNPs) in 35 candidate genes were genotyped for 711 sporadic OPLL patients and 896 controls. The differences in allelic and genotypic distribution between patients and controls were assessed using the chi (2) test with Bonferroni's correction. We also analyzed the association by separating patients into subgroups according to sex, age and the number of ossified vertebrae. The nominal P values fell below 0.05 for five SNPs in three genes. An intronic SNP in the TGF3 gene (P=0.00040) showed the most significant association. Previously reported associations of COL11A2, NPPS and TGFB1 with OPLL could not be reproduced. Further, no significant associations were detected in stratified analyses based on sex, age or the number of ossified vertebrae. TGFB3 warrants further investigation because it is located within a genomic region that has been positively linked with OPLL.

Adolescent↗

PubMed2006

Contribution of runt-related transcription factor 2 to the pathogenesis of osteoarthritis in mice after induction of knee joint instability.

OBJECTIVE: By producing instability in mouse knee joints, we attempted to determine the involvement of runt-related transcription factor 2 (RUNX-2), which is required for chondrocyte hypertrophy, in the development of osteoarthritis (OA). METHODS: An experimental mouse OA model was created by surgical transection of the medial collateral ligament and resection of the medial meniscus of the knee joints of heterozygous RUNX-2-deficient (Runx2+/-) mice and wild-type littermates. Cartilage destruction and osteophyte formation in the medial tibial cartilage were compared by histologic and radiographic analyses. Localization of type X collagen and matrix metalloproteinase 13 (MMP-13) was examined by immunohistochemistry. Localization of RUNX-2 was determined by X-Gal staining in heterozygous RUNX-2-deficient mice with the lacZ gene insertion at the Runx2-deletion site (Runx2+/lacZ). Messenger RNA levels of type X collagen, MMP-13, and RUNX-2 were examined by real-time reverse transcriptase-polymerase chain reaction analysis. RESULTS: RUNX-2 was induced in the articular cartilage of wild-type mice at the early stage of OA, almost simultaneously with type X collagen but earlier than MMP-13. Runx2+/- and Runx2+/lacZ mice showed normal skeletal development and articular cartilage; however, after induction of knee joint instability, they exhibited decreased cartilage destruction and osteophyte formation, along with reduced type X collagen and MMP-13 expression, as compared with wild-type mice. CONCLUSION: RUNX-2 contributes to the pathogenesis of OA through chondrocyte hypertrophy and matrix breakdown after the induction of joint instability.

Animals↗

PubMed2006

Cartilage tissue engineering using human auricular chondrocytes embedded in different hydrogel materials.

To seek a suitable scaffold for cartilage tissue engineering, we compared various hydrogel materials originating from animals, plants, or synthetic peptides. Human auricular chondrocytes were embedded in atelopeptide collagen, alginate, or PuraMatrix, all of which are or will soon be clinically available. The chondrocytes in the atelopeptide collagen proliferated well, while the others showed no proliferation. A high-cell density culture within each hydrogel enhanced the expression of collagen type II mRNA, when compared with that without hydrogel. By stimulation with insulin and BMP-2, collagen type II and glycosaminoglycan were significantly accumulated within all hydrogels. Chondrocytes in the atelopeptide collagen showed high expression of beta1 integrin, seemingly promoting cell-matrix signaling. The N-cadherin expression was inhibited in the alginate, implying that decrease in cell-to-cell contacts may maintain chondrocyte activity. The matrix synthesis in PuraMatrix was less than that in others, while its Young's modulus was the lowest, suggesting a weakness in gelling ability and storage of cells and matrices. Considering biological effects and clinical availability, atelopeptide collagen may be accessible for clinical use. However, because synthetic peptides can control the risk of disease transmission and immunoreactivities, some improvement in gelling ability would provide a more useful hydrogel for ideal cartilage regeneration.

Atrial Appendage↗