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Biomedical subjects

K Kobayashi

Publications and source records attributed to K Kobayashi.

At least 127 records · Page 7Linked to original sources
PubMed2003

Expression of auxiliary beta subunits of sodium channels in primary afferent neurons and the effect of nerve injury.

Multiple voltage-gated sodium channels are the primary mediators of cell excitability. They are multimers that consist of the pore-forming alpha subunit and auxiliary beta subunits. Although ion permeability and voltage sensing are primarily determined by the alpha subunit, beta subunits are important modulators of sodium channel function. The purpose of this study was to assess the effect of axotomy on the expression of beta subunits (beta(1), beta(2) and beta(3)) and coexpression of Na(v)1.3 and beta(3) subunits in the dorsal root ganglion (DRG). We used sciatic nerve transection models or spared nerve injury (SNI) models in the rat. In reverse transcriptase-polymerase chain reaction analysis, there were no significant differences between contralateral and ipsilateral DRGs of beta(1) and beta(2) mRNA 3 days after axotomy. beta(3) mRNA expression in ipsilateral DRGs increased significantly compared with contralateral DRGs 3 days after axotomy. In in situ hybridization histochemistry, beta(1) mRNA was predominantly expressed in medium- to large-size neurons, whereas beta(2) mRNA was expressed in small- to large-size neurons. There were no significant differences in beta(1) and beta(2) mRNA between contralateral and ipsilateral DRGs 3 days after axotomy. In contrast, beta(3) mRNA was mainly expressed in small neurons and occasionally in medium- to large-size neurons, and beta(3) mRNA expression in small c-type neurons in ipsilateral DRGs was increased significantly compared with contralateral DRGs. We examined beta(3) mRNA expression with one of alpha subunits, Na(v)1.3-ir, in DRG neurons after axotomy using the double labeling method. We found a high percentage of coexpression in injured DRG neurons: 83.6+/-2.8% of neurons expressing beta(3) mRNA were labeled for Na(v)1.3-ir; 70.1+/-3.1% of Na(v)1.3-ir neurons expressed beta(3) mRNA. We also examined the expression of beta(3) mRNA in DRG neurons in the SNI model, a neuropathic pain model. We used activating transcription factor 3 to identify axotomized neurons, and found that beta(3) mRNA up-regulation occurred mainly in axotomized neurons in the neuropathic pain model. These data strongly suggest that beta(3) expression in injured DRG neurons following axotomy might be an important pathomechanism of post-nerve injury pain in primary sensory neurons.

Activating Transcription Factor 3↗
PubMed2003

Genetic variation in hypoxia-inducible factor 1alpha and its possible association with high altitude adaptation in Sherpas.

Hypoxic stress at high altitude requires adaptations in several physiological functions to ensure the optimal oxygenation of all cells. Several lines of evidence suggested that high-altitude native populations such as Sherpas have been genetically adapted to their stressful environment. We investigated the genetic variation in the hypoxia-inducible factor (HIF)-1alpha gene in Sherpas as compared with Japanese, native lowlanders, and found a novel dinucleotide repeat polymorphism in intron 13 of the HIF-1alpha gene. GT15 allele was more frequent in Japanese than in Sherpas with statistical significance, while GT14 allele was significantly more frequent in Sherpas as compared with Japanese. A possible genetic variation in the HIF-1alpha gene might function in adaptation to living at high altitude. Because the activity of HIF-1 is regulated by multiple steps including the transcriptional level, the effect of the polymorphism in intron 13 on the cellular hypoxic responses remains to be elucidated.

Adaptation, Physiological↗
PubMed2003

Long-term effect of sodium hyaluronate (Hyalgan) on osteoarthritis progression in a rabbit model.

BACKGROUND: Intra-articular (IA) hyaluronan (HA) injections are approved for the treatment of knee osteoarthritis (OA) pain. One of the currently available products is approved for repeat treatment courses. While HA is classed as a symptom-modifying agent, there is substantial evidence that this therapeutic modality also possesses disease-modifying activity. OBJECTIVE: A rabbit model of OA, anterior cruciate ligament transection (ACLT), was used to investigate the long-term effects of single and sequential courses of HA therapy on OA progression. DESIGN: One or two courses of five weekly IA injections of sodium hyaluronate (Hyalgan) average molecular weight, MW, of 500-730 kDa, or vehicle were administered to rabbits (N=10 per group), initiated 4 and 13 weeks (for groups that received a second course) after ACLT. Gross morphological and histomorphometric evaluations were performed on harvested knee joints following sacrifice at 26 weeks after surgery. RESULTS: All the rabbits exhibited the characteristic pathologic changes of OA. Rabbits that received one or two courses of HA injections showed less disease progression than rabbits treated with ACLT alone or with 10 vehicle injections. However, rabbits that received five vehicle injections also showed improved morphology compared with those given no injections. Rabbits that received 10 HA injections showed significantly less surface roughness of the femoral cartilage compared with rabbits treated with ACLT, 5 HA injections, or 10 vehicle injections, and showed significantly less surface roughness of the tibial plateau compared with all other treatment groups (P<0.05). CONCLUSIONS: Repeat courses of HA injections reduced the degree of articular degeneration in a rabbit ACLT model of OA. Sequential courses of HA therapy may be advantageous in the long-term management of OA.

Animals↗
PubMed2003

Effects of rebamipide, a gastro-protective drug on the Helicobacter pylori status and inflammation in the gastric mucosa of patients with gastric ulcer: a randomized double-blind placebo-controlled multicentre trial.

AIMS: To investigate the effects of rebamipide on the Helicobacter pylori eradication rate with amoxicillin and omeprazole. The trial also examined its histological effects on gastro-mucosal inflammation after eradication. METHODS: Two hundred and six H. pylori-positive patients with active gastric ulcer underwent 8-week based therapy (OA) consisting of 2-week amoxicillin with omeprazole and subsequent 6-week omeprazole. They randomly received either rebamipide (OA-R) or placebo (OA-P) for 16 weeks: combined with the OA based therapy, and subsequently for another 8 weeks. Besides eradication rate, inflammatory findings of gastric mucosa after eradication were evaluated histologically. RESULTS: Per Protocol Set analysis showed no significant difference in eradication rate between OA-R (64.6%; 95% confidence interval, 54.3-75.0%) and OA-P (67.9%; 95% CI, 57.6-78.3%). Histological findings in the gastric mucosa of the ulcer region, however, indicated a significant improvement (P = 0.017) in inflammation scores in OA-R (1.84 +/- 0.41) compared with that in OA-P (2.02 +/- 0.39) after 16-weeks of treatment. This suppressive effect on inflammation was observed even in the OA-R patients unsuccessfully eradicated. CONCLUSION: Rebamipide demonstrated a suppressive effect on the persistent and possibly chronic inflammation in the gastric mucosa of the ulcer region after eradication, but the drug did not improve the eradication rate.

Adult↗
PubMed2003

Cyclooxygenase-2 expression in thyroid neoplasms.

AIMS: Previous studies have demonstrated that cyclooxygenase-2 (COX-2) plays a role in carcinogenesis and carcinoma development. In this study, we investigated its expression in thyroid neoplasms in order to elucidate its role. METHODS AND RESULTS: COX-2 expression was studied immunohistochemically in 20 anaplastic (undifferentiated) carcinomas, 49 papillary carcinomas, 22 follicular carcinomas and 15 follicular adenomas. Positive staining was only occasionally seen in normal follicles or stromal cells. COX-2 over-expression was found in only 20.0% of follicular adenomas and 40.9% of follicular carcinomas. In papillary carcinomas, the incidence (81.3%) was significantly higher (P < 0.0001) than in follicular carcinomas, although COX-2 expression was reduced in cases with old age (P = 0.0190), large size (P = 0.0028), advanced stage (P = 0.0225), satellite tumours (P = 0.0363), and the presence of solid, scirrhous or trabecular growth patterns (P = 0.0018). Undifferentiated carcinomas less frequently over-expressed COX-2 (P = 0.0004), with an incidence of 40.0%. CONCLUSIONS: These results indicate that the up-regulation of COX-2 may contribute predominantly in the early phase of papillary carcinoma progression, whereas it plays a more adjuvant role in follicular carcinoma progression.

Carcinoma↗
PubMed2003

Syndecan-1 expression in thyroid carcinoma: stromal expression followed by epithelial expression is significantly correlated with dedifferentiation.

AIM: To investigate the expression of syndecan-1 in thyroid neoplasia. Syndecan-1 is a proteoglycan regulating cell adhesion. Previous studies have demonstrated that decreased expression of syndecan-1 is linked to malignant progression. METHODS AND RESULTS: Syndecan-1 expression in thyroid neoplasia was studied immunohistochemically. Syndecan-1 was expressed in stromal cells as well as neoplastic epithelial cells. Stromal syndecan-1 expression was observed more frequently in papillary carcinomas larger than 10 mm in size than in microcarcinomas and in widely invasive than in minimally invasive follicular carcinomas. Furthermore, poorly differentiated carcinomas showed this phenomenon more than well-differentiated carcinomas, but the expression in undifferentiated carcinomas was similar to that of poorly differentiated carcinomas. Epithelial syndecan-1 expression was more frequently observed in anaplastic (undifferentiated) carcinomas than in papillary and follicular carcinomas. No significant difference in epithelial expression was found between well and poorly differentiated carcinomas, but undifferentiated carcinomas expressed epithelial syndecan-1 more frequently than did poorly differentiated carcinomas. CONCLUSIONS: These results are in contrast to those previously reported for carcinomas at other sites. It is suggested that the role of syndecan-1 in thyroid carcinomas might be unique. Stromal syndecan-1 expression followed by its epithelial expression is significantly related to progression, including dedifferentiation of thyroid carcinoma.

Adenocarcinoma↗
PubMed2003

Demonstrating nanophotonic switching using near-field pump-probe photoluminescence spectroscopy of CuCl quantum cubes.

We demonstrated a novel optical switching operation using three CuCl quantum cubes with a size ratio of. Their quantized excitonic energy levels resonate with one another, and the switching mechanism was based on the resonant near-field energy transfer between the quantum cubes. Using near-field pump-probe photoluminescence spectroscopy, we succeeded in controlling the near-field energy transfer and obtained a controlled (i.e. switched) signal in a differential photoluminescence spectrum with and without a pump beam. The internal quantum efficiency of the switching operation was close to 1. These results suggest the possibility of making a nanophotonic switching device smaller than 30 nm.

Copper↗
PubMed2003

Excitation dynamics in a three-quantum dot system driven by optical near-field interaction: towards a nanometric photonic device.

Using density operator formalism, we discuss interdot excitation energy transfer dynamics driven by the optical near-field and phonon bath reservoir, as well as coherent excitation dynamics of a quantum dot system. As an effective interaction between quantum dots induced by the optical near-field, the projection operator method gives a renormalized dipole interaction, which is expressed as a sum of the Yukawa functions and is used as the optical near-field coupling of quantum dots. We examine one- and two-exciton dynamics of a three-quantum dot system suggesting a nanometric photonic switch, and numerically obtain a transfer time comparable with the recent experimental results for CuCl quantum dots.

Journal Article↗
PubMed2003

A method for controlling the spins of atoms using optical near-fields.

On the basis of the procedure for controlling the spins of atoms using circularly polarized evanescent light proposed by Hori et al.[(1996) Abstracts of the 1st Asia-Pacific Workshop on Near-field Optics] we discuss the influence of boundary conditions on the probability of spontaneous emission and thus on the spin polarization efficiency, which was not considered in the Hori et al. study. Using the Carniglia-Mandel mode expansion of electromagnetic fields, we derive the spontaneous emission and spin polarization probabilities of atoms near a dielectric surface, and show the atom-surface distance dependence and refractive index dependence. Numerical evaluation for the 6P1/2-6S1/2 transition of a Cs atom indicates an increase in the efficiency of spin polarization by 30%.

Journal Article↗
PubMed2003

Mandibular condyle movement during mastication of foods.

This study evaluated the mandibular condyle displacement on the working side while masticating certain foods with different textures. For referencing the mandibular condyle movement, the range of voluntary border movement of the mandibular condyle was determined based on the analysis of the sagittal, left lateral and right lateral border motion using Posselt's figure. The test foods consisted of cheese, peanuts, and beef jerky. During mastication of cheese and peanuts, the amount of displacement of the mandibular condyle in all directions was within the range of border movement. Significant posterior and superior shifts of the mandibular condyle were observed during mastication of beef jerky, compared with the findings obtained during border movement. Accordingly, it is suggested that prolonged mastication of hard fibrous foods, may stimulate the temporomandibular joint structure and mandibular dysfunction patients should limit their intake of such foods.

Adult↗
PubMed2003

Mucoepidermoid carcinoma of the esophagus treated by endoscopic mucosal resection.

Mucoepidermoid carcinoma is a mixed cell tumor with both adenocarcinomatous and squamous components. We report a rare case of superficial mucoepidermoid carcinoma of the esophagus with mucosal gastric cancer. Endoscopic mucosal resection was performed on a 67-year-old man with a slight but defined depressed lesion of the thoracic esophagus and two lesions of mucosal gastric cancer. Histological examination revealed that the lesion of the esophagus was a mucoepidermoid carcinoma and the two lesions of the stomach were well-differentiated adenocarcinoma. Since the mucoepidermoid carcinoma had only slightly invaded the submucosal layer, it was thought to arise from the ductal epithelium of the esophageal gland or the stratified squamous epithelium of the esophagus. Radiation therapy with a total dose of 60 Gy was performed and there has been no recurrence or metastasis to other organs during 36 months of follow-up.

Aged↗
PubMed2003

Mexiletine carbonyloxy beta-D-glucuronide: a novel metabolite in human urine.

1. The study was performed to isolate and characterize a glucuronic acid conjugate of mexiletine that releases mexiletine on acid hydrolysis from urine samples obtained from healthy volunteers following a single oral dose of mexiletine. 2. The [M-H]- ion of the isolated metabolite was observed at m/z 398 in the negative electrospray ionization mass spectrum. This mass number was 44 higher than that of the product generated when mexiletine is subjected to direct glucuronidation. In positive-ion mode, collision-induced dissociation of the quasimolecular ion [M+NH4]+, m/z 417, gave product ions at m/z 224, 180 and 58. These mass spectral data indicated that the metabolite contained a carbonyloxy moiety in its structure in addition to mexiletine and a glucuronic acid moiety. 3. The presence of this carbonyloxy moiety was further supported by the following chemical reactions. When the metabolite was hydrolysed with an aqueous solution of 1 M sodium hydroxide at room temperature, mexiletine was released, whereas the N-methoxycarbonyl derivative of mexiletine was obtained after treatment of the metabolite with methanolic sodium hydroxide solution. 4. The results indicated that the structure of the isolated metabolite was the N-carbonyloxy beta-D-glucuronic acid conjugate of mexiletine.

Adult↗
PubMed2003

Interstitial lung disease associated with juvenile dermatomyositis: clinical features and efficacy of cyclosporin A.

OBJECTIVES: Interstitial lung disease (ILD) is a rare complication of juvenile dermatomyositis (JDM). The aim of this study was to clarify the clinical features of JDM-associated ILD and to evaluate the efficacy of cyclosporin A (CSA). METHODS: We reviewed clinical records of 10 cases of JDM that were admitted to Hokkaido University Hospital between April 1990 and March 2001. RESULTS: Five cases were complicated with ILD, three with interstitial pneumonia and two with bronchiolitis obliterans organizing pneumonia. ILD was associated with active JDM and progressed despite corticosteroid therapy. Testing for anti-Jo-1 antibody was negative in all cases. Respiratory symptoms were initially noticed in only one case. In the other cases, ILD was first detected by routine examination of chest X-ray. All the cases received CSA (3-5 mg/kg/day) in combination with prednisolone. One patient died of respiratory failure, but the others responded well to treatment with CSA. CONCLUSION: ILD should be evaluated carefully in all cases of JDM regardless of respiratory symptoms. CSA is a choice for steroid-resistant cases of JDM-associated ILD.

Adolescent↗
PubMed2003

Purification and characterization of the flagellar basal body of Rhodobacter sphaeroides.

Flagellar hook-basal body (HBB) complexes were purified from Rhodobacter sphaeroides. The HBB was more acid labile but more heat stable than that of Salmonella species, and protein identification revealed that HBB components were expressed only from one of the two sets of flagellar gene clusters on the R. sphaeroides genome, under the heterotrophic growth conditions tested here.

Bacterial Proteins↗
PubMed2003

Oxidized low-density lipoprotein as a risk factor of thrombosis in antiphospholipid syndrome.

Beta2-Glycoprotein I (beta2-GPI) is a major antigen for anticardiolipin antibodies (aCL, Abs) present in patients with antiphospholipid syndrome (APS). We recently reported that oxidized LDL(oxLDL) is subsequently targeted by beta2-GPI and anti-beta2-GPI auto-Abs and that-carboxyl variants of 7-ketocholesteryl esters, such as 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) and 7-ketocholesteryl-12-carboxy (keto) octadodecanoate (oxLig-2), are ligands for beta2-GPI (J Lipid Re 2001; 42: 697; J Lipid Res 2002; 43: 1486). These beta2-GPI ligands provide an electrostatic interaction between oxLDL and beta2-GPI followed by forming stable complexes (such as Schiff base adducts). The omega-carboxyl function in these ligand is responsible for beta2-GPI binding to oxLDL and the oxLDL-beta2-GPI complexes are anti-beta2-GPI auto-Ab-dependently taken up by macrophages (i.e., by phagocytosis). Our recent observations are consistent with the evidence that beta2-GPI co-localizes with lymphocytes and mononuclear cells in human athero-plaques. Thus, autoimmune thrombogenesis (atherogenesis) is linked to interaction of anti-beta2-GPI Abs with the beta2-GPI-oxLDL complexes. We propose an alternative idea, that an immune response against the beta2-GPI-oxLDL complexes may be involved in mechanisms in the development of atherosclerosis, which has been explained by the theory of 'the response to injury'.

Antigen-Antibody Complex↗
PubMed2003

Computed tomography of odontogenic myxoma.

OBJECTIVES: The purpose of this study was to clarify the CT features of odontogenic myxoma. METHODS: CT appearances were analysed in 17 patients with histologically verified odontogenic myxoma collected from five dental hospitals in Japan. RESULTS: On the CT images, tumour borders were generally well defined with a smooth margin both for bony and soft tissue structures in all patients. Cortical status was clearly evaluated using CT and the continuity was interrupted in nine patients. Intralesional trabeculations were observed in 13 patients. Of these 13, 6 patients showed the characteristic appearance of angular or straight trabeculations within the tumour. The trabeculations were frequently observed at the peripheral portion of the tumour. In three maxillary tumours, soft tissue margins were observed beyond the cortical margin and/or intralesional trabeculations. In 10 of the 13 lesions evaluated, the majority of the whole tumour area showed relatively lower density compared with surrounding muscles. CONCLUSION: CT clearly demonstrated characteristic features of odontogenic myxoma. CT analysis may contribute to establishing a consensus regarding the interpretation of conventional radiographic appearances in odontogenic myxoma.

Adolescent↗
PubMed2003

A possible target of antioxidative therapy for diabetic vascular complications-vascular NAD(P)H oxidase.

A growing body of evidence has shown that oxidative stress may be involved in the development of vascular complications associated with diabetes. However, the molecular mechanism for increased reactive oxygen species (ROS) production in diabetes remains uncertain. Among various possible mechanisms, attention have increasingly been paid to NAD(P)H oxidase as the most important source of ROS production in vascular cells. High glucose level stimulates ROS production through protein kinase C (PKC)-dependent activation of vascular NAD(P)H oxidase. Furthermore, the expression of NAD(P)H oxidase components is increased in micro- and macrovascular tissues of diabetic animals in association with various functional disorders and histochemical abnormalities. These results suggest that vascular NAD(P)H oxidase-driven ROS production may contribute to the onset or development of diabetic micro- or macrovascular complications. In this point of view, the possible new strategy of antioxidative therapy for diabetic vascular complications is discussed in this review.

Animals↗