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Naoki Kobayashi

Publications and source records attributed to Naoki Kobayashi.

At least 37 records · Page 2Linked to original sources
PubMed2004

Morphologic changes in the cervical neural foramen due to flexion and extension: in vivo imaging study.

STUDY DESIGN: Dimensional measurement of cervical neural foramen at various positions, using reformatted computed tomography. OBJECTIVES: To examine the morphologic changes in the neural foramen during flexion and extension of the cervical spine in vivo. SUMMARY OF BACKGROUND DATA: Previous cadaveric studies have shown the effect of cervical spinal motion on dimensions of the neural foramen. However, little information is available about dynamic morphologic changes in the cervical neural foramen in vivo. METHODS: Cervical CT images of seven healthy volunteers were taken at the neutral position, maximum extension, and maximum flexion, and were reconstructed in the oblique plane perpendicular to the long axis of each neural foramen from the C3-C4 to C6-C7 level. Measured parameters included foraminal height, width, cross-sectional area, and segmental sagittal rotation at each spinal level. Differences in neural foraminal dimensions among these positions were analyzed. Correlations of segmental sagittal rotation with differences in dimensions between flexion and extension were analyzed. RESULTS: Flexion significantly increased the foraminal height (by 1.0 mm; 11%), foraminal width (by 1.0 mm; 16%), and foraminal area (by 12 mm2; 28%) (P < 0.01). Extension significantly decreased the foraminal height (by 0.9 mm; 10%), foraminal width (by 1.4 mm; 22%), and foraminal area (by 8.0 mm2; 17%) (P < 0.01). Segmental sagittal rotation significantly positively correlated with % change in foraminal height (r = 0.434, P < 0.01) and area (r = 0.504, P < 0.01). CONCLUSIONS: The present results are consistent with those of previous in vitro studies and may explain the clinical observation that cervical extension aggravates symptoms in patients with cervical radiculopathy and that flexion often relieves them.

Adult↗
PubMed2004

Cutting edge: expression of chemokine receptor CXCR1 on human effector CD8+ T cells.

IL-8 is a potent inflammatory cytokine that induces chemotaxis of neutrophils expressing CXCR1 and CXCR2, thus indicating its involvement in the migration of these cells to inflammatory sites where bacteria proliferate. Presently, we showed that CXCR1(+) cells were predominantly found among CD8(+) T cells having effector phenotype, and that the expression of CXCR1 was positively correlated with that of perforin, suggesting that CXCR1 is expressed on effector CD8(+) T cells. Indeed, human CMV-specific CD8(+) T cells from healthy individuals, which mostly express the effector phenotype and have cytolytic function, expressed CXCR1, whereas EBV-specific CD8(+) T cells, which mostly express the memory phenotype and have no cytolytic function, did not express this receptor. The results of a chemotaxis assay showed that the migration of CXCR1(+)CD8(+) T cells was induced by IL-8. These results suggest that the IL-8-CXCR1 pathway plays an important role in the homing of effector CD8(+) T cells.

Antigens, Viral↗
PubMed2004

Down-regulation of CXCR4 expression on human CD8+ T cells during peripheral differentiation.

Multi-color flow cytometric analysis on human CD8(+) T cell subsets revealed that CXCR4 is predominantly expressed on CD8(+) T cells with the naive CD27(+)CD28(+)CD45RA(+) phenotype, and is down-regulated during differentiation into those with an effector phenotype. The down-regulation of CXCR4 expression during peripheral differentiation was supported by the fact that the expression of CXCR4 on CD8(+) T cells was negatively correlated with that of perforin. The analysis of CCR5, CCR7, and CXCR4 co-expression further showed that CD8(+) T cells expressing a high level of CXCR4 are CCR7(+)CCR5(-) naive or central memory subsets, and those expressing a low level of CXCR4 were included in the CCR7(-)CCR5(+/-) memory/effector and effector subsets. Epstein Barr virus-specific CD8(+) T cells, which mostly express the memory phenotype, expressed CXCR4, while human cytomegalovirus-specific CD8(+) T cells, which mostly express the effector phenotype, partially expressed this receptor, showing that the expression of CXCR4 is also down-regulated during differentiation of viral antigen-specific CD8(+) T cells. The classification of human CD8(+) T cells based on the expression of these chemokine receptors should prove useful for studies that clarify the differentiation of human CD8(+) T cells.

CD8-Positive T-Lymphocytes↗
PubMed2004

Hepatic delivery of particulates in the submicron range by a hydrodynamics-based procedure: implications for particulate gene delivery systems.

BACKGROUND: A large-volume intravenous (i.v.) injection of DNA, i.e. a hydrodynamics-based transfection procedure, is known to be an efficient and liver-specific method of in vivo gene delivery. However, little is available on an applicable particle size in the procedure. METHODS: We examined the effect of particle size on the hepatic delivery by the hydrodynamics-based procedure, using fluorescein isothiocyanate labeled polystyrene microspheres (MS) of 50, 200 or 500 nm in diameter. MS were injected intravenously to mice by a conventional (normal) or the hydrodynamics-based procedure and their degree of hepatic uptake was determined fluorometrically. RESULTS: For all sizes tested, the two procedures were similar in terms of the apparent degree of hepatic uptake, whereas the intrahepatic localization of MS was apparently different between the procedures as shown by an examination of frozen tissue sections. In mice with gadolinium chloride induced Kupffer cell blockade, the hepatic uptake of MS following the normal procedure was decreased while that of the hydrodynamics-based procedure was less affected. This phenomenon of enhanced hepatic delivery seemed to be more effective for larger particles. Confocal microscopic observation of hepatocyte suspensions indicated that part of the injected MS-50 was delivered intracellularly following the hydrodynamics-based procedure, whereas almost all the observed MS-200 and MS-500 were detected in the extracellular compartment or on the surface of the cells. This was supported by the fact that most of the injected MS existed pericellularly around the transgene-expressing cells. CONCLUSIONS: The hydrodynamics-based procedure facilitated extravasation and hepatic delivery of MS. Larger MS were more efficiently extravasated and trapped by the liver, whereas intracellular delivery hardly occurred with them.

Animals↗
PubMed2004

Hydrodynamics-based procedure involves transient hyperpermeability in the hepatic cellular membrane: implication of a nonspecific process in efficient intracellular gene delivery.

BACKGROUND: The mechanisms underlying the efficient gene transfer by a large-volume and high-speed intravenous injection of naked plasmid DNA (pDNA), a so-called hydrodynamics-based procedure, remain unclear and require further investigation. In this report, we have investigated possible mechanisms for the intracellular transport of naked pDNA by this procedure. METHODS: Propidium iodide (PI), a fluorescent indicator for cell membrane integrity, and luciferase- or green fluorescent protein (GFP)-expressing pDNA were injected into mice by the hydrodynamics-based procedure. RESULTS: PI was efficiently taken up by hepatocytes which appeared to be viable following the hydrodynamics-based procedure. Pre-expressed GFP in the cytosol was rapidly eliminated from the hepatocytes by a large-volume injection of saline. The profiles of plasma ALT and AST showed a steady decline with the highest values observed immediately after the hydrodynamics-based procedure. These results suggest that the hydrodynamics-based procedure produces a transient increase in the permeability of the cell membrane. The cellular uptake process appeared nonspecific, since simultaneous injection of an excess of empty vector did not affect the transgene expression. Sequential injections of a large volume of pDNA-free saline followed by naked pDNA in a normal volume revealed that the increase in membrane permeability was transient, with a return to normal conditions within 30 min. Transgene expression was observed in hepatocyte cultures isolated 10 min after pDNA delivery and in the liver as early as 10 min after luciferase-expressing RNA delivery, indicating that pDNA delivered immediately by the hydrodynamics-based procedure has the potential to produce successful transgene expression. CONCLUSIONS: These findings suggest that the mechanism for the hydrodynamics-based gene transfer would involve in part the direct cytosolic delivery of pDNA through the cell membrane due to transiently increased permeability.

Animals↗
PubMed2004

Interleukin-6, interleukin-8, and soluble tumor necrosis factor receptor-I in the cord blood as predictors of chronic lung disease in premature infants.

OBJECTIVES: In order to predict the late-development of chronic lung disease of prematurity (CLD), cytokines in the cord blood were assessed in this study. STUDY DESIGN: Eighteen premature infants with CLD were enrolled. Cord blood plasma levels of cytokines of these infants and 12 control infants without CLD were measured including interleukin (IL)-1beta, IL-2, IL-4, IL-6, IL-8, IL-10, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, soluble TNF receptor-I, and soluble IL-6 receptor using a cytometric bead array and an enzyme-linked immunosorbent assay. RESULTS: The cord blood IL-6, IL-8, and sTNFR-I levels were significantly elevated in CLD infants compared with those in control (P < .05). IL-1beta, IL-2, IL-4, IL-10, and IFN-gamma were undetectable in both groups. CLD infants with maternal chorioamnionitis had higher IL-6 than those without chorioamnionitis (P < .01). In CLD infants, IL-6 was higher in the infants who required prolonged oxygen therapy (P < .05). CONCLUSION: Elevated inflammatory cytokines in the cord blood are associated with the progression to CLD.

Case-Control Studies↗
PubMed2004

Significant role of liver sinusoidal endothelial cells in hepatic uptake and degradation of naked plasmid DNA after intravenous injection.

PURPOSE: Uptake and degradation of naked plasmid DNA (pDNA) by liver sinusoidal endothelial cells (LSECs) were investigated. METHODS: Tissue distribution and intrahepatic localization were determined after an intravenous injection of 111In- or 32P-labeled pDNA into rats. Cellular uptake and degradation of fluorescein- or 32P-labeled pDNA were evaluated using primary cultures of rat LSECs. RESULTS: Following intravenous injection, pDNA was rapidly eliminated from the circulation and taken up by the liver. Fractionation of liver-constituting cells by centrifugal elutriation revealed a major contribution of LSECs to the overall hepatic uptake of pDNA. Confocal microscopic study confirmed intracellular uptake of pDNA in cultured LSECs. Apparent cellular association of pDNA was similar at 37 degrees C and 4 degrees C. However, trichloroacetic acid (TCA) precipitation experiments showed the TCA-soluble radioactivity in the culture medium increased in an accumulative manner at 37 degrees C. Involvement of a specific mechanism was demonstrated, as the uptake of pDNA was significantly inhibited by excess unlabeled pDNA and some polyanions (polyinosinic acid, dextran sulfate, heparin) but not by others (polycytidylic acid, dextran). These inhibitors also reduced the amount of TCA-soluble radioactivity in the culture medium. CONCLUSION. These results suggest that LSECs efficiently ingested and rapidly degraded naked pDNA in vivo and in vitro and released the degradation products into the extracellular space.

Animals↗
PubMed2004

Dynamic movement of cytochrome c from mitochondria into cytosol and peripheral circulation in massive hepatic cell injury.

BACKGROUND: In the process of apoptosis, it is known that the transition of cytochrome c from mitochondria into the cytosol occurs, and tumor necrosis factor (TNF)-alpha is one of the molecules responsible for this event. But in the state of hypercytokine induced by D-galactosamine (D-GaIN)/Lipopolysaccharide (LPS), the localization of cytochrome c is little known. METHODS: Rats were administrated with D-GaIN(700 mg/kg)/LPS(200 microg/kg). Blood and tissue samples were collected and examined for levels of pro-inflammatory cytokines, the apoptosis of liver cells, and the localization of cytochrome c. RESULT: Before administration of D-GaIN/LPS, cytochrome c was definitely localized in the mitochondria. At 2 h after simultaneous administration of D-GaIN/LPS, cytochrome c had accumulated in the cytosol following abrupt increases of plasma TNF-alpha. Massive cell destruction due to apoptosis proved by Terminal deoxynucleo-tidyl transferase-mediated dUTP nick end labeling staining was observed in liver tissue 4 h later and markedly increased levels of cytochrome c were detected in the plasma 12 h after D-GaIN/LPS administration. CONCLUSION: Liver injury induced by simultaneous administration of D-GaIN/LPS was closely associated with the production of TNF-alpha, and also with the dynamic movement of cytochrome c from the mitochondria into the cytosol, and then into the systemic circulation. The detection of plasma cytochrome c levels may be a useful clinical tool for the detection of apoptosis in vivo.

Animals↗
PubMed2004

[Current status of treatment for patients with idiopathic thrombocytopenic purpura in the Hokkaido area (evaluation of Helicobacter pylori eradication)].

Treatment guidelines for patients with idiopathic thrombocytopenic purpura (ITP) have been changed recently due to the clinical application of Helicobacter pylori (H. pylori) eradication but there has been no detailed multi-center analysis of the hematological effects of H. pylori eradication. The Clinical Hematology Forum consists of 11 large hematological departments and divisions in the Hokkaido area. We sent questionnaires to these 11 hematological departments and divisions in March 2003 to obtain information on current treatment strategies for patients with ITP and hematological results after the eradication of H. pylori. Questionnaires were returned by 9 (81.8%) of the 11 departments. Doctors in all hospitals had experience in diagnosis and treatment of H. pylori infection. Diagnostic examinations for H. pylori infection were performed in 54.3% of the registered cases. H. pylori infection was detected in 68.1% of the examined cases, and eradication treatment was performed in 87.7% of H. pylori-positive patients. H. pylori was eradicated in 52 (83.9%) of the 62 patients in whom the results of treatment could be evaluated. Among the patients whose platelet counts were less than 10.0 x 10(4)/microl, platelet recovery was observed in 48.8% of cases with successful eradication, a percentage similar to previously reported percentages in Japan. There was no prognostic factor to predict good responders before eradication treatment. Since the side effects of eradication treatment, including gastrointestinal symptoms and skin eruptions, were not serious, this method might become a front-line treatment for patients with ITP. Patient selection for eradication as an up-front treatment, analysis of the pathophysiology of platelet recovery after eradication and long-term effects should be investigated to make new treatment guidelines for newly diagnosed patients with ITP.

Adolescent↗
PubMed2003

Vector-based in vivo RNA interference: dose- and time-dependent suppression of transgene expression.

RNA interference (RNAi) induced by delivery of a small-interfering RNA (siRNA)-expressing vector was characterized in mice. siRNA-expressing plasmid DNA (pDNA) was injected by a hydrodynamics-based procedure along with pDNA encoding an exogenous target luciferase gene. A comparative study showed that stem-loop-type siRNA-expressing pDNA was superior, in terms of the transgene suppressive efficacy, to the tandem-type in the liver following systemic delivery of these pDNAs. Transgene suppression occurred in the liver, kidney, and lung as well as muscle. The degree of suppression was dependent on the dose of siRNA-expressing pDNA and the time at which transgene expression was determined following simultaneous injection of siRNA-expressing and target pDNAs. A reduction in transgene expression became apparent at 1 day after injection, whereas a lower degree of inhibition was obtained before this, as early as 6 h even in mice treated with an excess of siRNA-expressing pDNA. These results suggest that delivery of siRNA-expressing pDNA requires a period of time for induction of RNAi. A study of sequential injections revealed that prior injection of siRNA-expressing pDNA produced a significant suppression for at least 1 day, which disappeared within 4 days. Confocal microscopic studies indicated that the localization of the cells with successful delivery of transgene was different between primary and secondary hydrodynamics-based injections, accounting for the less effective inhibition following the sequential injections. Taken together, these results demonstrate that vector-based in vivo RNAi is a dose- and time-dependent process and offers the possibility of suppressing endogenous targets in a variety of somatic cells.

Animals↗
PubMed2003

Association of the Japanese Orthopaedic Association score with the Oswestry Disability Index, Roland-Morris Disability Questionnaire, and short-form 36.

STUDY DESIGN: Cross-cultural translation and cross-sectional psychometric testing were performed. OBJECTIVES: To cross-culturally translate the Oswestry Disability Index (ODI) and the Roland-Morris Disability Questionnaire (RMDQ) into Japanese, and to compare the Japanese Orthopaedic Association (JOA) score with the ODI and the RMDQ score. SUMMARY OF BACKGROUND DATA: The two most widely used back-specific measures, the ODI and the RMDQ, have not been translated into Japanese. The JOA score has been used extensively in Japan. However, this score has not been tested in terms of its reliability and validity. METHODS: The ODI and RMDQ were translated into Japanese using the process of forward translation, synthesis of translation, backward translation, expert committee, test of the prefinal version, and submission of the documentation to the developers. The JOA score, ODI, and RMDQ were tested with 97 patients who had degenerative lumbar spinal disorders (average age, 51 years). The correlation among the three disease-specific measures (JOA score, ODI, and RMDQ) and eight subscales of a generic health measure, the Medical Outcomes Survey Short-Form 36 (SF-36), was calculated. The reproducibility of the JOA score also was investigated. RESULTS: Reliability, as estimated by internal consistency, reached a Cronbach alpha of 0.83 for the ODI and 0.86 for the RMDQ. The calculated test-retest reliability was 0.93 (P < 0.01; n = 20) for the ODI and 0.95 (P < 0.01; n = 20) for the RMDQ. The correlation of the JOA score with the ODI was -0.647 (P < 0.01), and with RMDQ was -0.568 (P < 0.01). There also was a significant correlation between the ODI and the RMDQ (r = 0.785; P < 0.01). There was a significant correlation between the three disease-specific measures (JOA score, ODI, and RMDQ) and all the subscales of the SF-36 (P < 0.01). The calculated reproducibility of the JOA score was as follows: interobserver error (r = 0.92, P < 0.01), test-retest reliability (r = 0.91, P < 0.01). CONCLUSIONS: The Japanese versions of the ODI and the RMDQ were reliable and valid. The use of these translated instruments can be recommended for future clinical trials in Japan. The results also showed the JOA score had acceptable psychometric properties of reliability and construct validity, suggesting that this score is reliable and valid. Further studies are needed to verify the validity and responsiveness of the JOA score.

Cross-Cultural Comparison↗
PubMed2003

Disposition and gene expression characteristics in solid tumors and skeletal muscle after direct injection of naked plasmid DNA in mice.

Previous studies have suggested that direct injection of naked plasmid DNA (pDNA) into solid tumors can be a useful method for in vivo gene transfer into tumor cells. To gain more insight into this approach, we studied the disposition and gene expression characteristics of naked pDNA after intratumoral injection by direct comparison with those after intramuscular injection in mice. pDNA encoding reporter genes were directly injected into subcutaneous solid tumor models and skeletal muscles. Biodistribution studies using radiolabeled pDNA showed that the elimination of pDNA from the injection site was relatively fast and a part of the pDNA was absorbed from the lymphatic system after both local injections. Confocal microscopic studies using fluorescein-labeled pDNA demonstrated that pDNA distributed efficiently throughout the muscle tissue whereas pDNA localization in the tumor tissue was restricted. Characterization of gene expression clarified the variation in expression level between tumor preparations and some factors affecting the expression level in the tumor. Reporter gene expression was significantly inhibited by simultaneous administration of some polyanions in both cases, suggesting that a specific mechanism may be involved in the naked pDNA uptake by muscle and tumor cells. These findings provide useful information for direct naked pDNA delivery into solid tumors.

Animals↗
PubMed2003

A case of leukemia of the appendix presenting as acute appendicitis.

A 71-year-old man was admitted to our hospital because of right lower abdominal pain. He was suspected of having acute appendicitis and soon after admission, appendectomy was performed. Macroscopically, the appendix was greatly swollen and reddened, but had no abscess. Microscopically, polymorphonuclear leukocytes were not found, but diffuse infiltration of atypical cells was observed. Examination of a bone marrow aspirate revealed 74% blasts that were peroxidase stain positive. We diagnosed acute myelogenous leukemia (FAB classification, M2). He received induction chemotherapy, but died 49 days after admission. Leukemic cell infiltration of the appendix is rare and acute appendicitis as the initial manifestation of leukemia is even rarer.

Aged↗
PubMed2003

Construction of a BAC library for Haplochromis chilotes, a cichlid fish from Lake Victoria.

Cichlid fishes in Lake Victoria are model organisms for studying rapid radiation and speciation. On the way to examine the molecular basis of how these cichlid fishes achieved such a remarkable morphological diversification, we constructed a bacterial artificial chromosome (BAC) library derived from a cichlid species, Haplochromis chilotes, from Lake Victoria. The library includes 157,056 clones with the average insert size of 128 kb, corresponding to a 10-fold coverage of the H. chilotes genome. Given that the cichlid fishes endemic to Lake Victoria are closely related to one another phylogenetically and their genomes are nearly identical, this BAC library can be utilized to isolate genes from the more than 200 Haplochromine cichlid species in Lake Victoria.

Animals↗
PubMed2003

Enlarging vertebral body pneumatocysts in the cervical spine.

An intravertebral pneumatocyst is a relatively rare condition, and its natural course and etiology are unclear. We report a case of intravertebral pneumatocysts in the C5 vertebra that gradually enlarged during a 16-month period as documented by follow-up CT. In addition, direct communication was observed between the gas in the intervertebral disk and another pneumatocyst in the C6 vertebral body, which suggests that the gas in the pneumatocyst had an association with the gas in the degenerated intervertebral disk.

Aged↗
PubMed2002

Therapeutic effect of intravenous interferon gene delivery with naked plasmid DNA in murine metastasis models.

Interferons (IFNs) exhibit pleiotropic biological activities that are considered to play important roles in tumor suppression and rejection. Therefore, IFN genes are promising for in vivo cytokine gene therapy targeted against tumors. In the present study, we evaluated the efficacy of hydrodynamics-based IFN gene transfer for tumor treatment, in which the naked pDNA encoding IFN-beta or IFN-gamma was administered into the tail vein of mice following portal vein (liver metastasis), tail vein (lung metastasis), or subcutaneous injection (subcutaneous tumor) of mouse colon carcinoma CT-26 cells. A substantial amount of IFN was soon markedly expressed in the liver and a transient increase in IFN activity was detected in the circulation. This procedure caused transgene-specific IFN production with little induction of other proinflammatory cytokines. In the liver metastasis experiment, the mice treated with IFN-expressing pDNA displayed a profound reduction in liver metastasis and a prolonged survival. Administration of the pDNA at an earlier stage of metastasis was more crucial for the antitumor effect. Similar tumor suppression was seen in the lung metastasis experiment. These therapeutic effects were more marked with IFN-beta-expressing pDNA treatment than with IFN-gamma-expressing pDNA treatment. On the other hand, subcutaneous CT-26 tumor growth was hardly affected by pDNA administration. These results suggest that the hydrodynamics-based transfer of naked pDNA is a convenient and efficient method of IFN gene therapy against metastatic tumors.

Animals↗
PubMed2002

Pharmacokinetics and preventive effects of targeted catalase derivatives on hydrogen peroxide-induced injury in perfused rat liver.

PURPOSE: To investigate the pharmacokinetics and preventive effects of liver-targeted catalase (CAT) derivatives on hepatic injury caused by reactive oxygen species. METHODS: The hepatic uptake of 111In-CAT, galactosylated (Gal-), mannosylated (Man-) and succinylated (Suc-) CAT was investigated in isolated perfused rat livers in a single-pass constant infusion mode. Then, pharmacokinetic parameters were obtained by fitting equations derived from a one-organ pharmacokinetic model to the outflow profile. Their effects in preventing hydrogen peroxide-induced injury were determined by lactate dehydrogenase (LDH) release from the perfused liver. RESULTS: The extraction of CAT derivatives by the liver was dose-dependent, and increased by the chemical modifications described. After being bound to the cell surface, chemically modified CAT derivatives were internalized by the liver faster than CAT. Preperfusion of a CAT derivative significantly reduced LDH release by hydrogen peroxide at least for 30 min, and Man-CAT and Suc-CAT effectively inhibited this release. CONCLUSIONS: Internalized CAT derivatives are also effective in degrading hydrogen peroxide and targeted delivery of CAT to liver nonparenchymal cells by mannosylation or succinylation is a useful method for the prevention of hepatic injury caused by reactive oxygen species.

Animals↗