Biomedical subjects

T Matsunobu

Publications and source records attributed to T Matsunobu.

10 recordsLinked to original sources

PubMed2004

Modulation of activator protein 1/DNA binding activity by acoustic overstimulation in the guinea-pig cochlea.

Changes in gene expression are part of the homeostatic machinery with which cells respond to external stimuli or assaults. The activity of the early response transcriptional factor activator protein-1 (AP-1) can be modulated by a variety of environmental stimuli including those that alter the cellular oxidation/reduction status. This study investigates the activation of AP-1/DNA binding in the guinea-pig cochlea in response to acoustic overstimulation which produces reactive oxygen species. Electrophoretic mobility shift assays revealed that binding of AP-1 to its radiolabeled oligonucleotide probe markedly changed in nuclear extracts of inner ear tissues following intense noise exposure (4 kHz octave band, 115 dB, 5 h). AP-1/DNA binding increased in the organ of Corti and the lateral wall tissues immediately after the exposure, returning to near-baseline levels 5 h later. At 15 h after noise, a second peak of binding activity occurred in the organ of Corti whereas stria vascularis showed a lesser but more sustained activity. Binding in nuclear extracts from the spiral ganglion did not change. Incubation of nuclear extracts with antibodies against Fos/Jun family proteins prior to a supershift assay showed Fra-2 as a major component of the AP-1 complex immediately after the noise exposure. In the organ of Corti, Fra-2 immunoreactivity was localized to the middle turn, i.e. the region which is most affected by the 4-kHz octave band exposure. The results suggest the modulation of gene expression via the activation of AP-1 as a consequence of noise trauma but also demonstrate differential responses in cochlear tissues.

Acoustic Stimulation↗

PubMed2001

Downregulation and forced expression of EWS-Fli1 fusion gene results in changes in the expression of G(1)regulatory genes.

Chromosomal translocation t(11;22)(q24:q12) is detected in approximately 90% of tumours of the Ewing family (ET). This translocation results in EWS-Fli1 gene fusion which produces a EWS-Fli1 fusion protein acting as an aberrant transcriptional activator. We previously reported that the inhibition of EWS-Fli1 expression caused the G(0)/G(1)arrest of ET cells. We, therefore, hypothesized that EWS-Fli1 may affect the expression of G(1)regulatory genes. Downregulation of EWS-Fli1 fusion proteins was observed 48 hours after the treatment with EWS-Fli1 antisense oligonucleotides. The expressions of G(1)cyclins, cyclin D1 and cyclin E, were markedly decreased in parallel with the reduction of EWS-Fli1 fusion protein. On the other hand, the expression of p21 and p27, which are important cyclin-dependent kinase inhibitors (CKIs) for G(1)--S transition, was dramatically increased after the treatment with EWS-Fli1 antisense oligonucleotides. RT-PCR analysis showed that alteration of the expressions of the cyclins and CKIs occurred at the mRNA level. Furthermore, transfection of EWS-Fli1 cDNA to NIH3T3 caused transformation of the cells and induction of the expression of cyclin D1 and E. Clinical samples of ET also showed a high level of expression of cyclin D1 mRNA, whereas mRNAs for p21 and p27 were not detected in the samples. These findings strongly suggest that the G(1)--S regulatory genes may be involved in downstream of EWS-Fli1 transcription factor, and that the unbalanced expression of G(1)--S regulatory factors caused by EWS-Fli1 may lead to the tumorigenesis of ET.

3T3 Cells↗

PubMed2001

Acetylcholine-evoked calcium increases in Deiters' cells of the guinea pig cochlea suggest alpha9-like receptors.

The medial efferent system innervates outer hair cells in the organ of Corti. Neurotransmission at this synapse is mediated by acetylcholine (ACh) acting on nicotinic ACh receptors containing the alpha9 subunit. In addition to the sensory cells, the supporting cells of the mammalian cochlea also receive efferent innervation but the neurotransmitter(s) at these synapses are not known. We show slow transient increases of intracellular calcium evoked by ACh in isolated Deiters' cells of the guinea pig cochlea. The antagonists atropine, d-tubocurarine and strychnine blocked the ACh-effect. Nicotine was an ineffective agonist. The pharmacologic profile and the kinetics of the calcium response suggest an alpha9-like ACh receptor on Deiters' cells similar but not identical to that on the outer hair cells.

Acetylcholine↗

PubMed2001

Improvement of production of Kojic acid by a mutant strain Aspergillus oryzae, MK107-39.

A strain designated MK107-39, producing kojic acid with a high yield, was obtained by a new screening method using a 96-well microtiter plate after NTG treatment of Aspergillus oryze ATCC 22788. The amount of kojic acid produced by strain MK107-39 in a shaking flask was 28 g/l from 100 g/l of glucose, which was 7.7-times higher than that produced by parent strain. The kojic acid yields per cell and the amount of glucose consumed were 9.8 and 6.0-times higher than those of the parent strain. Based on differences in the use of carbohydrates and organic acids, it seems that strain MK107-39 has some mutation regarding carbohydrate metabolism. By customizing the medium and culture conditions such as glucose concentration, dissolved oxygen concentration and pH of the fermentation broth, more than 110 g/l of kojic acid was produced in a 3-l jar fermentor. Upon scale up to a 600-l pilot fermentor, enhanced production of kojic acid was successfully achieved. The kojic acid yield from glucose consumed, Y(P/S), was 0.43 (g/g) in this pilot plant-scale fermentation.

Journal Article↗

PubMed2000

Nitric oxide/cyclic GMP pathway attenuates ATP-evoked intracellular calcium increase in supporting cells of the guinea pig cochlea.

We demonstrate here that nitric oxide (NO) attenuates ATP-evoked calcium transients in Deiters' and Hensen's cells, "supporting" (nonsensory) cells of the guinea pig cochlea, by means of activation of soluble guanylyl cyclase and protein kinase G. The enzymatic activities associated with the nitric oxide/cGMP/protein kinase G pathway had previously been demonstrated to be present in Deiters' and Hensen's cells. We now isolate these cells and measure changes in intracellular free calcium by using the calcium indicator fluo-3. In Deiters' cells, calcium increased rapidly in response to the application of ATP. The increase was attenuated when the pathway was stimulated by NO donors (diethylamine NONOate or sodium nitroprusside) or the cyclic GMP analog, 8-bromo-cyclic GMP. When the activation of the pathway was blocked by the additional presence of inhibitors of soluble guanylyl cyclase (LY83583) or protein kinase G (Rp-8-bromo-cyclic GMP or KT5823), the response to ATP was restored. The reactions also occurred in calcium-free media. Hensen's cells responded similarly. These results provide evidence that intracellular calcium is regulated by the NO/cGMP/protein kinase G pathway in the inner ear.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2000

Acoustic trauma enhances DNA binding of transcription factor AP-1 in the guinea pig inner ear.

Radiolabeled probes for the transcription factor, activator protein-1 (AP-1), bound differentially to nuclear fractions of discrete structures of the guinea pig cochlea (organ of Corti, lateral wall tissues, and spiral ganglion). Noise exposure (4 kHz octave band, 115 dB, for 5 h) significantly increased AP-1 binding in both the organ of Corti and lateral wall tissues but not in the spiral ganglion. Supershift analysis using an antibody against c-Fos protein demonstrated that enhancement of AP-1/DNA binding was at least in part due to the expression of c-Fos protein. These results suggest that AP-1 is involved in the molecular mechanism(s) mediating noise-induced cochlear damage.

Animals↗

PubMed1999

Radiological assessment of the position of the tibial tuberosity by means of a marking wire in knees with patellofemoral arthritis.

OBJECTIVE: To assess the usefulness of a new axial radiographic technique in knees with patellofemoral arthritis (PF-OA). DESIGN AND PATIENTS: After a marking wire had been attached to the skin on the tibial tuberosity so that the wire matched the width of the patellar tendon, an axial radiograph was taken at 30 degrees of flexion in 16 normal knees and 14 PF-OA knees in which computed tomographic analysis had revealed a laterally positioned tibial tuberosity at 30 degrees of flexion. The distance of the marking wire from the lateral condyle and from the patellar groove was compared between the two groups. RESULTS: The marking wire was located significantly laterally in PF-OA knees compared with normal knees. CONCLUSION: An axial radiograph with a marking wire on the tibial tuberosity is useful for assessing the position of the tibial tuberosity in PF-OA knees.

Aged↗

PubMed1999

Changes in knee alignment after total knee arthroplasty.

Changes in limb alignment after total knee arthroplasty were evaluated in 20 knees replaced with the Miller Galante knee system. The mean follow-up period was 87.4 months. Seventeen of the 20 knees were in the varus position on the initial postoperative radiographs, but the alignment significantly changed to become even more aligned toward varus during the follow-up period. The thickness of the ultra-high-molecular-weight polyethylene (UHMWPE) also decreased significantly in the medial femorotibial joint. The wear of the UHMWPE possibly changed the alignment, and the postoperative alignment had a positive correlation with the wear rate. The components should be implanted so that the mechanical axis intersects the center of the components to prevent worsening of alignment as well as to minimize any such wear.

Aged↗

PubMed1999

Knee stability in posterior cruciate ligament retaining total knee arthroplasty.

Anteroposterior knee laxity was evaluated in 14 patients (19 knees) who had posterior cruciate ligament retaining total knee arthroplasty using the Miller Galante I prosthesis. The followup ranged from 87 to 118 months (average, 105.9 months), and the measurements were done using the KT-2000 arthrometer. The mean anteroposterior displacement with the knees with Miller Galante I prostheses was 10.1 mm at 30 degrees flexion and 8.1 mm at 75 degrees flexion. In the 15 knees with Miller Galante I prostheses with flexion greater than 90 degrees, seven had less stability at 75 degrees than at 30 degrees flexion. These knees were considered to have a nonfunctional posterior cruciate ligament, and they had a worse Knee Society score (81.1) than did the other eight knees with Miller Galante I prostheses (89.9). There were four knees in which the flexion was less than 90 degrees. In this study, approximately half of the knees with posterior cruciate ligament retaining total knee arthroplasty did not have good anteroposterior stability in flexion an average of 9 years after surgery.

Aged↗

PubMed1994

[Detection of autoantibodies in sera from patients with rheumatoid arthritis].

Although Rheumatoid Arthritis (RA) is categorized in the systemic autoimmune diseases, specific autoantibodies in RA have been reported to be rare. We have investigated autoantibodies found in sera from patients with RA and examined their clinical significance. Immunoprecipitation techniques using 32P-labeled or 35S-labeled HeLa cell extracts and immunoblotting were utilized to detect autoantibodies in sera from 42 patients with RA and 58 patients with other connective tissue diseases as controls. Certain autoantibodies were detected in 33 of 42 patients (79%) with RA by any of the assay systems mentioned above. Anti-SSA/Ro, anti-SSB/La, anti-7-2RNP, and anti-Sm antibodies were found in 13 (29%), 3 (7%), 4 (10%), and 1 (2%) patients with RA, respectively. All 3 patients with anti-SSB/La and 9 with anti-SSA/Ro revealed Sjögren's syndrome besides RA. However, all 4 patients with anti-7-2RNP and one patient with anti-Sm showed no evidence of scleroderma nor SLE. Besides of these known autoantibodies, we have also detected 4 new antibodies which reacted with a 60kD protein in 15 (36%), 45kD in 10 (24%), 75kD in 8 (19%), 180kD in 4 patients (10%) with RA. These autoantibodies were not found in other connective tissue diseases except one of SLE for anti-60kD and one of dermatomyositis for anti-75kD, and therefore appeared to be specific for RA patients. Anti-45kD antibodies were associated with low prevalence of anti-nuclear antibodies, and anti-180kD antibodies were associated with lymphadenopathy and Sjögren's syndrome. Thus, it was demonstrated that patients with RA develop a variety of autoantibodies as well as those with other connective tissue diseases.

Arthritis, Rheumatoid↗