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Biomedical subjects

N Ohata

Publications and source records attributed to N Ohata.

At least 19 recordsLinked to original sources
PubMed2004

[Chronic traumatic aneurysm of the thoracic aorta; report of a case].

We report a rare case of chronic traumatic aneurysm of the thoracic aorta. A 23-year-old man flew down from the fifth floor of his apartment for an attempted suicide. He suffered right subdural hematoma, bilateral hemothorax, lung contusions, and many other traumas. He was paralyzed by the fracture and dislocation of the first lumbar vertebra. Posterior fixation of lumbar vertebra and the segmental resection of the jejum were performed on the first and third day, respectively. He recovered well; however, he complained his nocturnal dyspnea on the forty-fifth day. Detailed examinations showed that bilateral bronchi were compressed by the aneurysm of thoracic aorta. Elective operation was performed on the sixty third day. Psudoaneurysm, 5 cm in diameter, was disclosed in the aortic isthmus. Graft replacement was undergone with the cardiopulmonary bypass. His postoperative course was uneventful, and he was transferred for the rehabilitation of his paralysis on the eigty-eighth day.

Adult↗
PubMed2001

Analyses of muscular activity, energy metabolism, and muscle fiber type composition in a patient with bilateral masseteric hypertrophy.

Hyperwork of the masseter muscles due to habitual parafunction is thought to induce masseteric hypertrophy (so called work hypertrophy). However, the causes underlying this disease are not yet fully understood. Recently, we had a patient with bilateral masseteric hypertrophy, and we performed a partial excision of the masseter muscles. In this patient's case, we examined muscular activity, energy metabolism, and fiber type composition of the masseter muscles using electromyograms (EMG), 31P-magnetic resonance spectroscopy (MRS), and enzyme-histochemistry. The EMG showed no hyperactivity, and the 31P-MRS showed normal energy spectral patterns and PCr contents of the masseter muscles. The fiber type composition, however, in the muscles in this case was very different from that in muscles with "work hypertrophy" and also that in normal masseter muscles: 1. Loss of type IIB fibers; 2. Increases in type IIA and in type IM & IIC fibers; and 3. Decrease in type I fibers. The findings suggest that this is not a case of work hypertrophy but a case of compensatory hypertrophy possibly due to a lack of high-tetanus-tension type IIB fibers.

Adenosine Triphosphate↗
PubMed2001

Fabrication of a functionally graded dental composite resin post and core by laser lithography and finite element analysis of its stress relaxation effect on tooth root.

Laser lithography was applied for Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) fabrication of dental prostheses made of composite resin. First, the conditions to obtain the optimum resolution for photo-curing were determined, and then a composite resin full crown was fabricated by laser lithography. Second, a functionally graded composite resin post and core which had gradient elasticity in the post, was manufactured by the gradual change in the filler contents of the composite resin. Finally, stress analysis of the functionally graded post and core was performed by a two-dimensional finite element method. This demonstrated the effects of reducing the stress concentration around the apex of the post.

Composite Resins↗
PubMed2001

Biomechanical effects of cervical lesions and restoration on periodontally compromised teeth.

OBJECTIVE: The purpose of this study was to photoelastically evaluate the effects of cervical root lesions and their restoration on stress distribution in periodontally compromised teeth. METHOD AND MATERIALS: Three-dimensional composite photoelastic models of a maxillary first premolar with buccal cervical root lesions were fabricated. Two different lesion configurations, wedge- and shallow saucer-shaped, at 20% alveolar bone height reduction were tested. A 35% reduction model was given a wedge-shaped lesion. The lesions were restored with microfine resin composite. Vertical loads of 7.5 lbs were applied to the unrestored and restored models at the tip of the buccal cusp and the tip of the lingual cusp. The resulting stresses within the tooth models were monitored and recorded photographically in the field of a circular polariscope arrangement. RESULTS: For buccal cusp loading of the unrestored models, stress concentrated at the apex of the lesion regardless of the lesion shape or periodontal support conditions. The highest stress concentration was observed around the apex of the wedge-shaped lesion on the 35% reduction model. Restoring the lesions changed stress distribution. Restoration of the lesions resulted in a marked stress reduction at the lesion apex. Stress along the gingival restoration-model interface was characteristic for the restored situation. The interfacial stress followed the contour of the restoration most closely for the wedge-shaped lesion on the 20% support reduction model. CONCLUSION: The shape and dimension of the lesion as well as periodontal support status has considerable influence on stress distribution, especially around the lesion, restored or not restored.

Alveolar Bone Loss↗
PubMed1999

Firing shrinkage of porcelain-resin composites prepared by laser lithography.

Using porcelain and resin-mixed composites as experimental materials, cubic polymerized composites were prepared by the accumulation of thin slices cured by laser scanning. The composites were then fired, and bulk ceramic bodies were made. The optimal firing conditions of polymerized composites and firing shrinkage were investigated. The results showed that cubic ceramic bodies in a form homologous to that before firing could be reproduced. The volume shrinkage of fired ceramic bodies consisting of 1 g of ceramic powders and 0.3 g of epoxy resin was about 30% under all firing conditions, and there were no significant differences between specimens. It was suggested that with further research and development, three-dimensional forms for clinical use in dentistry could be manufactured by the proposed method.

Dental Porcelain↗
PubMed1995

Multiphasic modulation of signal transduction into T lymphocytes by monoiodoacetic acid as a sulfhydryl reagent.

Actions of monoiodoacetic acid (MIA) as a sulfhydryl reagent on the different stages of the T cell receptor (TCR)-mediated signal transduction were examined. MIA (1 mM) prevented anti-TCR (CD3) monoclonal antibody (mAb)-induced energy-dependent receptor capping but at the same time promoted the anti-CD3 mAb/mitogen-induced tyrosine phosphorylation of the T cell activation-linked cellular proteins of 120, 80, 70, 56, and 40 kDa. Relatively low concentration (0.01 mM) of MIA further promoted anti-CD3 mAb-induced transcription of c-fos, production of IL-2, and cell surface expression of IL-2 receptors. The MIA-promoted TCR-mediated IL-2 production actually required signal transduction that could be inhibited by cyclosporin A, genistein, or H-7. In contrast, the same concentration of MIA as promoted the signal transduction for cell activation severely inhibited the anti-CD3 mAb-triggered signal delivery for cell proliferation, selectively at its early stage. We conclude from these results that MIA differentially affects various steps of signaling into T lymphocytes, suggesting that there exist multiple sites of MIA-sensitive or redox-linked control in the signal cascade.

Animals↗
PubMed1993

[The importance of the host nutritional and immune status on the prognosis of urinary tract infection in the elderly].

This study was performed to evaluate the role of the nutritional and immune status on the prognosis of urinary tract infections (UTI) in the elderly. 192 patients among the 790 inpatients were diagnosed as UTI. Age-related increase in the prevalence of UTI was accompanied with poor prognosis in the patients with hypoalbuminemia (< 2.6 g/dl) and lymphocytopenia (< 700/mm3). To study the immunologic basis for susceptibility to UTI in the aged further, we compared the T-cell functions between outpatients without serious disease and inpatients with chronic UTI. The absolute numbers of lymphocyte, OKT3 (pan T-cell marker), OKT4 (Helper/Inducer marker) and Interleukin (IL)-2 as well as serum albumin concentration were decreased in the patients with UTI. A prospective study was done to confirm that these nutritional and immunological changes become risk factors in the prognosis of UTI with long-term and low-dose chemotherapy. In the patients continued with bacteriuria (Non-responders, n = 6), serum albumin concentration and IL-2 production were significantly lower than the patients who became free from bacteriuria (Responders, n = 7). These results suggest that poor nutrition-related immune dysfunction contributes to the vulnerability of elderly patients to UTI and becomes risks for he prognosis of UTI.

Adult↗
PubMed1992

Enhanced DNA synthesis in rat hepatoma cells by conditioned media from Kupffer cells incubated with supernatants of tumor necrosis factor-alpha-pretreated hepatocytes.

The effects of tumor necrosis factor-alpha (TNF-alpha) on DNA synthesis in AH66 rat hepatoma cells and rat hepatocytes were analysed by means of [3H]thymidine incorporation. DNA synthesis in AH66 cells was suppressed when AH66 cells were directly incubated with TNF-alpha. When primary culture of rat Kupffer cells was incubated with hepatocyte conditioned media pretreated with TNF-alpha (0-200 U/ml), and AH66 cells were then treated with these hepatocyte/Kupffer cell-conditioned media, TNF-alpha used in the pretreatment caused a dose-dependent increase in DNA synthesis in AH66 cells with a maximum effect amounting to a more than 10-fold increase. In contrast, DNA synthesis in primary culture of rat hepatocytes was not stimulated by the TNF-alpha-pretreated hepatocyte/Kupffer cell conditioned media. These results suggest that TNF-alpha-mediated hepatocyte-Kupffer cell interaction selectively promotes proliferation of rat hepatoma cells.

Animals↗
PubMed1991

[Long-term single dose chemoprophylaxis of recurrent urinary tract infection in elderly female subjects].

To evaluate the efficacy of the single dose chemoprophylaxis of recurrent urinary tract infection (UTI) in the elderly, 20 female inpatients (mean age 81.4) who had one or more culture documented UTIs in the past 12 months were studied. They were randomly assigned to be treated for 6 months either with chemoprophylaxis (200 mg of norfloxacin) or conventional therapy (without any antimicrobials except when overt UTI occurred). After a 4 months of washout period, the protocols were exchanged with each other and next 6 months of trial was carried out. All cases were followed at least 4 months after the discontinuance of the chemoprophylaxis. The difference of efficacy between the two modalities was evaluated by periodical examinations of urine cultures, urinalysis and inflammatory markers. During chemo-prophylaxis, the frequency of the symptomatic UTI (bacteriuria greater than 10(4)/ml, pyuria greater than 5/HPF, CRP greater than +) was 0.267/patient.year which was significantly lower than during conventional therapy (2.97/patient.year, p less than 0.01). This prophylactic effect remained 4 months after the discontinuance of the drug. On the other hand, bacteriuria was persistent in more than half of patients with chemoprophylaxis. Minimal inhibitory concentration of norfloxacin for separated bacteria revealed that the resistant species steeply increased from 4 to 6 months after the beginning of chemoprophylaxia. These species disappeared 4 months after the drug was discontinued. Optimal durations of chemoprophylaxis and drug-holidays were discussed.

Aged↗
PubMed1990

[Well controlled comparative study in early rheumatoid arthritis with gold sodium thiomalate vs. auranofin].

RA Center Liaison Council conducted a comparative study of Auranofin and GST by envelope method on the patients with early RA who experienced the onset of the disease not more than two years ago. In final assessment of overall improvement, 57.9% of Auranofin-administered cases (22/38) showed moderate improvement or above. The comparable figure for GST group was 71.8% (28/39), but there was no statistically significant difference. Adverse reaction ADR incidence for Auranofin group was 12.2% (5/41), while 22.0% for GST (9/41), but the difference was not statistically significant. Drop out due to ADR was observed in 9.8% of Auranofin-administered cases and in 19.5% of GST-administered cases. The results of the study indicate that Auranofin is a most suitable DMARD than GST to be used for early RA, and GST is suitable for more active RA in view of its efficacy. But GST should be administered carefully because of its high ADR incidence.

Adolescent↗
PubMed1988

Vinigrol, a novel antihypertensive and platelet aggregation inhibitory agent produced by a fungus, Virgaria nigra. I. Taxonomy, fermentation, isolation, physicochemical and biological properties.

Vinigrol, produced by a fungal strain identified as Virgaria nigra, was extracted from the cultured mycelium, purified by solvent extraction followed by chromatography on silica gel and then isolated as crystals (C20H34O3, mp 108 degrees C). Vinigrol decreased arterial blood pressure of anesthetized normotensive rats dose-dependently when administered intravenously. Vinigrol inhibited platelet activating factor and epinephrine induced platelet aggregation.

Animals↗
PubMed1981

Correlation between the protease activities and the number of epithelial cells in human saliva.

The positive significant correlation (r = 0.788, n = 37) was shown between the protease activity and the number of epithelial cells (not of leukocytes) in saliva. There was little protease activity observed in glandular saliva. It is possible to conclude from the results that a main source of salivary protease is the epithelial cells in saliva. It was also found that the oral prophylaxis reduced the numbers of epithelial cells and leukocytes and the protease activity.

Adolescent↗