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Biomedical subjects

Y Ohtani

Publications and source records attributed to Y Ohtani.

At least 19 recordsLinked to original sources
PubMed2006

Effect of a thin HA coating on the stress/strain distribution in bone around dental implants using three-dimensional finite element analysis.

Three-dimensional finite element analysis was performed for thin hydroxyapatite (HA) coated and titanium dental implants to study the effects on stress/strain distribution in the mandible with application of axial and oblique loads. The implants were of screw and cylinder types. With an axial load, the maximum equivalent bone stresses in the titanium implants were 21.5 and 29.0 MPa for the cylinder and screw types respectively, and the stress and strain distributions differed. For the cylinder type, the highest stress was located at the implant base, and for the screw type, it was located at the top edge of the first thread within the cortical bone. For the HA-coated cylinder and screw implants, the maximum equivalent bone stresses were 7.1 and 7.2 MPa respectively. The stress and strain distributions were similar, and the highest stress was located on the upper side of the cortical bone around the implant neck for both implants. Of the implants examined, the screw type HA-coated implant had the most uniform stress distribution in bone.

Anisotropy↗
PubMed2005

Effect of MKC-733, a 5-HT receptor partial agonist, on bowel motility and symptoms in subjects with constipation: an exploratory study.

BACKGROUND: MKC-733, a 5-HT(3) receptor partial agonist, is a novel enteroprokinetic compound. OBJECTIVE: The aim of this study was to explore the effects of MKC-733 on bowel motility and symptoms in a small group of subjects with constipation. Tolerability was also examined. METHODS: The study was conducted in a single-blind and dose-escalation manner on 14 male and female subjects with constipation aged 22-67 years. After a 1 week run-in period, subjects were treated with placebo (b.i.d.) for 1 week, and 0.2 and 0.5 mg of MKC-733 (b.i.d.) for 2 weeks sequentially. Geometric mean and per cent elimination of surrogate markers of bowel motility were measured by a radio-opaque marker technique at the end of each treatment period. They were analysed on the whole group and subgroups with low (n = 6) and high (n = 8) bowel motility based upon the geometric mean value after placebo treatment. Subjects kept diaries of their bowel habits and gastrointestinal symptoms. RESULTS: Percent elimination increased after treatment with 0.5 mg MKC-733 compared with placebo treatment in the whole group (70.4 +/- 33.5% vs. 47.1 +/- 36.6%, mean +/- SD, P < 0.05). In the low bowel motility group, both geometric mean and percent elimination increased after treatment with 0.5 mg MKC-733 compared with placebo (7.1 +/- 0.9 vs. 5.9 +/- 0.5, P < 0.05; 60.0 +/- 35.8% vs. 13.3 +/- 19.4%, P < 0.05). Stool frequency increased after the first-week treatment with MKC-733 compared with placebo (P < 0.05). Numbers of sensation of incomplete evacuation and gastrointestinal symptoms decreased to half and less after the treatment with MKC-733. No serious adverse effect was noted. CONCLUSION: Multiple doses of 0.5 mg MKC-733 improve bowel motility, which was clearly demonstrated in the subjects with decreased bowel motility. MKC-733 at the doses studied might be effective in increasing stool frequency and reduce gastrointestinal symptoms related to constipation. MKC-733 was well tolerated. Further studies will be needed to clarify efficacy and safety of MKC-733 on a larger population.

Adult↗
PubMed2005

Chronic bird fancier's lung: histopathological and clinical correlation. An application of the 2002 ATS/ERS consensus classification of the idiopathic interstitial pneumonias.

BACKGROUND: Chronic bird fancier's lung (BFL) has often been misdiagnosed as one of the idiopathic interstitial pneumonias (IIPs). METHODS: To define the clinical and pathological characteristics of chronic BFL, 26 patients with chronic BFL from whom a surgical lung biopsy specimen was taken between October 1992 and June 2001 were evaluated. The histopathological characteristics of the surgical lung biopsy specimens were examined and correlations between the histopathology and clinical characteristics were analysed. The quality of chronic inflammatory and fibrotic changes was expressed according to the 2002 ATS/ERS consensus classification of IIPs. RESULTS: Two patients were diagnosed as having bronchiolitis obliterans organising pneumonia (BOOP)-like lesions, five as having cellular non-specific interstitial pneumonia (NSIP)-like lesions, and eight as having fibrotic NSIP-like lesions. The other 11 patients were considered to have usual interstitial pneumonia (UIP)-like lesions because of the temporal heterogeneous appearances of the fibrotic changes. However, fibrosis in these patients had developed in centrilobular as well as perilobular areas, suggestive of hypersensitivity pneumonitis. Nineteen patients (73.1%) had multinucleated giant cells, often with cholesterol clefts, while only five patients (19.2%) had granulomas. Patients with BOOP-like or cellular NSIP-like lesions tended to have recurrent acute episodes, whereas patients with UIP-like lesions had an insidious onset. Patients with BOOP-like or cellular NSIP-like lesions had a more favourable outcome than those with fibrotic NSIP-like and UIP-like lesions. CONCLUSIONS: The qualities of chronic inflammatory and fibrotic lesions vary significantly among patients with chronic BFL but correlate with clinical features and prognosis.

Aged↗
PubMed2004

Wiener filter-magnetoencephalography of visual cortical activity.

This paper reports a revised Wiener filter to resolve the inverse problem for magnetoencephalograms (MEGs) according to the structural and functional constraints based on magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI). Wiener filter-MEG imaging for half field stimulation with the chromatic stimulus resolved fast, slow and late responses in V1, V4 and the inferotemporal cortex, respectively. The time courses of these responses were roughly comparable with those reported by unit recording studies of the corresponding monkey visual cortical areas. Wiener filter-MEG imaging had comparable spatial resolution and better signal to noise ratio than fMRI. The background noise was robust in fMRI responses, but became virtually eliminated in Wiener filter responses. Wiener filter-MEG imaging with upper and lower quadrant field stimulation demonstrated V1 responses differentially distributed respectively in the lower and upper banks of the calcarine sulcus. These results demonstrate that responses in two cortical areas facing close to each other can be resolved by Wiener filter-MEG. The present method provides a way to image brain activities with millisecond- and millimeter-order spatiotemporal resolution.

Adult↗
PubMed2001

Leukemia inhibitory factor induces nociceptin mRNA in cultured rat cortical neurons.

The effects of leukemia inhibitory factor (LIF) on the expression of neurotransmitter synthetase and neuropeptide mRNAs in cultured rat cortical neurons were examined by reverse transcription-polymerase chain reaction. Nociceptin mRNA expression was increased by treatment with 20 or 80 ng/ml LIF for 24 h, but choline acetyl transferase, glutamic acid decarboxylase, enkephalin, dynorphin, substance P, somatostatin and galanin mRNA expression were not altered by LIF. These observations indicated a specific effect of LIF on nociceptin gene regulation in cultured cortical neurons.

Aging↗
PubMed2001

Efficient production of menaquinone (vitamin K2) by a menadione-resistant mutant of Bacillus subtilis.

Efficient production of menaquinone (MK) by Bacillus subtilis was achieved. An edible strain of B. subtilis, isolated from the traditional Japanese food natto, was mutated to improve MK productivity. A menadione-resistant mutant producing 30% more MK than its parent strain was obtained. Soybean extract and glycerol were the best nitrogen and carbon sources, respectively, among the sources tested. Addition of yeast extract also increased MK productivity. The maximum concentration of MK reached about 35.0 mg/l after 4 days of culture in a jar fermenter. The pH of the medium decreased to 5.5 after the start of cultivation, then spontaneously increased to 7.7-8.0. This pH change might be important in the production of MK because only small amounts of MK were obtained when pH was controlled at 5.7, 6.0, 7.0, 7.5 or 8.0.

Bacillus subtilis↗
PubMed2001

Pseudohyperkalaemia caused by recentrifugation of blood samples after storage in gel separator tubes.

Because hyperkalaemia above a certain level is life-threatening, erroneous interpretation of serum potassium concentration may misguide and complicate diagnostic procedures. We investigated a number of cases with pseudohyperkalaemia, which was assumed to have been caused by the recentrifugation of blood samples after storage in gel separator tubes. The time trend of serum potassium concentration was explored before (January-March 1997) and after (May-July 1997) ceasing the practice of recentrifuging blood samples after overnight storage. Next, we conducted an experiment on a volunteer's serum. The sample was divided into two groups and centrifuged once (control group) or twice (recentrifugation group). For both groups, serum potassium concentrations were measured immediately, and at 24, 48 and 72 h. For the recentrifugation group, the second centrifugation was done just before the measurement. The time series study showed that the mean serum potassium concentrations measured after overnight storage were 4.68 (95% CI: 4.60-4.76) mmol/L before and 4.14 (4.07-4.20) mmol/L after ceasing the practice of recentrifugation. The experiment showed that the mean serum potassium concentrations in the control group versus the recentrifugation group were 3.95 (95% CI: 3.89-4.01) mmol/L versus 4.05 (3.92-4.17) immediately (P=0.0979), 3.95 (3.89-4.01) versus 5.95 (5.61-6.29) at 24 h (P=0.0001), 4.13 (4.05-4.22) versus 6.90 (6.46-7.34) at 48 h (P=0.0001), and 4.22 (3.85-4.58) versus 7.61 (6.94-8.30) at 72 h (P<0.0001). Recentrifugation of blood samples after storage causes a spurious rise in serum potassium concentration to the degree of clinical significance. Clinicians and biochemists should take appropriate measures to stop this practice.

Artifacts↗
PubMed2001

Production of menaquinone (vitamin K2)-7 by Bacillus subtilis.

Menaquinone-7 (MK-7) is a highly bioactive homologue of vitamin K. We obtained a diphenylamine-resistant mutant strain D200-41 from Bacillus subtilis strain MH-1 which was isolated from fermented soybeans, natto. The mutant strain exhibited decreased production of MK-6. Using strain D200-41, efficient production of MK-7 was achieved. We found that, compared with an agitated and aerated culture, production of MK-7 was increased by static culture. The sporulation of the cells progressed more slowly in a static culture than in an agitated culture. The maximum concentration of MK reached about 60 mg/l in a medium containing 10% soybean extract, 5% glycerol, 0.5% yeast extract and 0.05% K2HPO4 (pH 7.3) when D200-41 cells as well as MH-1 cells were statically cultured at 45 degrees C for 5 d after being cultured with shaking at 37 degrees C for 1 d.

Journal Article↗
PubMed2001

Reconstruction of heavily calcified aorta and its visceral branches without extracorporeal circulation.

A 61-year-old Japanese female was referred to our hospital for surgical treatment of a localized heavily calcified abdominal aorta. Preoperative angiograms and computed tomograms revealed severe stenosis of the aorta, resembling a slit. Bypass grafting between the thoracic and abdominal aorta was successfully performed together with the reconstruction of the celiac artery, superior mesenteric artery, and bilateral renal arteries without extracorporeal circulation. Postoperative angiograms showed patency of the graft and branches. A localized heavily calcified abdominal aorta is relatively rare, and the cause of this entity might be Takayasu's aortitis.

Aged↗
PubMed2001

Postnatal development of lymphatic vessels and their smooth muscle cells in the rat diaphragm: a confocal microscopic study.

This paper reports on how lymphatic vessels and their smooth muscle cells develop in the diaphragm of postnatal rats. Lymphatic endothelial cells in the diaphragm were labeled by an intraperitoneal injection of DiI-labeled acetylated low-density lipoprotein (DiIac-LDL). During postnatal week 1, DiI-ac-LDL was detected in many free cells in addition to distinct endothelial cells that formed lymphatic vessels. Occasionally, saccular lymphatics isolated from previously formed lymphatics were recognized; these were referred to as lymphatic islands. The DiI-ac-LDL-labeled free and lymphatic endothelial cells showed immunoreactivity for CD 34 and Flt-4, but most of them did not express either OX 62 or ED 1 immunoreactivity, with only some showing ED 1 immunoreactivity. This suggests that most of the DiI-ac-LDL-labeled elements were lymphatic endothelial cells, and that some were macrophages. After postnatal week 1, the DiI-ac-LDL positive cells were restricted to lymphatic vessels. Until postnatal week 6, lymphatic vessels increased as the diaphragm enlarged. Towards the end of postnatal week 2, free cells expressing alpha-smooth muscle actin (alpha-SMA) immunoreactivity increased in the diaphragm, and some of these were in contact with lymphatics. A coarse plexus of smooth muscle cells surrounding the lymphatic vessels first appeared at postnatal week 2, and this plexus became denser with age. Our findings indicate that lymphatic vessels are formed not only by sprouting from previously formed lymphatic vessels but also by migrating endothelial cells, and that smooth muscle cells may be differentiated from mesenchymal cells to form a plexus surrounding the lymphatic vessels.

Animals↗
PubMed2001

[A case of Churg-Strauss syndrome in which positive rheumatoid factor and MPO-ANCA preceded the development of clinical symptoms of vasculitis].

A 52-year-old man in whom bronchial asthma had been diagnosed in 1995 was admitted for the treatment of Churg-Strauss syndrome in June 1997. Positive tests MPO-ANCA and rheumatoid factor preceded the symptoms of vasculitis for several months. A skin biopsy revealed infiltration of eosinophils in the vessel walls, and the diagnosis of Churg-Strauss syndrome was confirmed. After systemic administration of corticosteroids, the symptoms other than mononeuritis improved markedly, and his MPO-ANCA and rheumatoid factor became negative. Rheumatoid factor and MPO-ANCA may be useful for the early diagnosis of Churg-Strauss syndrome in patients with bronchial asthma in which a well-controlled disease develops into an intractable condition.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2001

Phylogeny and ontogeny of the lymphatic stomata connecting the pleural and peritoneal cavities with the lymphatic system--a review.

This paper reviews the phylogeny and ontogeny of "lymphatic stomata" through which fluids and cells in the pleural and peritoneal cavities enter the lymphatic system. In amphibians, the pleuroperitoneal cavity is connected through numerous pores with the wide subvertebral lymphatic sinus corresponding to the thoracic duct in mammals. In reptiles, direct connections of the pleural and peritoneal cavities with the lymphatic system have been reported. In mammals, the pleural and peritoneal cavities are directly connected with lymphatics through lymphatic stomata. How do lymphatic stomata develop in mammals? In the rat, distinct lymphatics are noted in the subpleural space of the diaphragm periphery in 16 days old embryo. With age, the supleural lymphatics increase and form a polygonal network. They show a tubular appearance and possess many valves. Some of them become endowed with smooth muscle cells. In 19 days old embryos, some lymphatics appear in the subperitoneal space of the diaphragm. They extend centripetally and form many lateral projections that later elongate and connect with those from adjacent lymphatics, thus forming a lattice-like network or "lymphatic lacunae". During early postnatal days, the lymphatic lacunae project many bulges that subsequently come into contact with the pores among mesothelial cells lining the diaphragmatic peritoneum, thus forming lymphatic stomata. They increase until postnatal week 10. The lymphatic stomata in the costal pleura also develop during early postnatal days.

Aging↗
PubMed2000

Visualization, quantification and therapeutic evaluation of angiogenic vessels in cancer by synchrotron microangiography.

The usefulness of a synchrotron microangiography system for depicting, quantitating and therapeutically evaluating angiogenic vessels in cancer is illustrated. In 20 mice transplanted with murine colon cancer, sequential changes in the angiogenic vessels were determined by using synchrotron microangiography, using changes in tumor volume for reference. This system allowed the depiction and quantification of angiogenic vessels in the period from one to four weeks after transplantation. The effects of antiangiogenic therapy were evaluated by using a neutralizing antibody against vascular endothelial growth factor. The neutralizing antibody partially suppressed angiogenesis and tumor growth. Synchrotron microangiography is shown to be useful for the depiction, quantification and evaluation of angiogenic vessels in cancer.

Journal Article↗
PubMed2000

Expression of inducible nitric oxide synthase mRNA and production of nitric oxide are induced by adenosine triphosphate in cultured rat microglia.

The effect of adenosine triphosphate (ATP) on the expression of the inducible nitric oxide synthase (iNOS) mRNA and production of nitric oxide in cultured rat microglia was examined. ATP induced iNOS mRNA dose-dependently (100-1,000 microM). The induction began within 1 h after addition of ATP (100 microM) with peak expression occurring at 6 h. The release of nitric oxide to culture medium was significantly increased by the treatment with ATP (100 and 1,000 microM) for 12 and 24 h. These results indicate that ATP is a potential mediator to induce iNOS mRNA expression and NO production in microglia.

Adenosine Triphosphate↗
PubMed2000

Enantioselective determination of bromoisovalerylurea by liquid chromatography on chiral stationary phase in reversed- or normal-phase partition mode.

Bromoisovalerylurea (bromvalerylurea) is a sedative-hypnotic given orally as a racemate. Enantiomers of this drug could be separated by high-performance liquid chromatography on the three chiral stationary phases (a vancomycin-bonded, beta-cyclodextrin derivative-bonded, or urea derivative-bonded phase). Biological fluids of human subjects who had ingested toxic or therapeutic doses of the racemate were chromatographed after liquid-liquid extraction. The (+)-enantiomer concentration was almost equal to the (-)-enantiomer concentration in the serum of one overdosed patient. In all the other subjects, the (+)-enantiomer was less than the (-)-enantiomer in their sera and saliva. The data suggest that the drug is absorbed non-stereoselectively from the gastrointestinal tract and eliminated from the blood stereoselectively.

Adult↗
PubMed2000

Neuroaxonal leukodystrophy associated with congenital cutis laxa: report of an autopsy case.

A male patient, who was born with congenital cutis laxa characterized by cutaneous laxity due to the degeneration of elastic fibers, presented with an arrest of mental and motor development at the age of 3 years. The progressive decline of the psychomotor abilities led to the patient's death at the age of 4 years and 9 months. An autopsy revealed extensive white matter degeneration, characterized by the formation of numerous neuroaxonal spheroids and a diffuse loss of axons and myelin sheaths. The centrum semiovale and the cerebellar white matter were the most severely affected. The ultrastructure of the spheroids was consistent with a dystrophic type of axonal swelling. Neurons of the cerebral cortex, cerebellar cortex, and some brain stem nuclei were lost in moderate to severe degrees, and there were relatively few neuroaxonal spheroids in the gray matter. The pallidum and substantia nigra were well preserved. Neuroaxonal leukodystrophy, in which the spheroid formation predominantly affects the white matter, is the rarest variant of primary neuroaxonal dystrophies, and there are very few reports of autopsied cases. Among the reported cases, two Japanese siblings had congenital skin lesions similar to those of our case. The unique association of neuroaxonal leukodystrophy and congenital cutis laxa may form a distinct variant in this disease category.

Brain↗