PubMed Health⌕ Search

Biomedical subjects

K Oki

Publications and source records attributed to K Oki.

At least 19 recordsLinked to original sources

Gamma-aminobutyric acid (GABA) and cell proliferation: focus on cancer cells.

In addition to its role in the adult mammalian nervous system as an inhibitory neurotransmitter, gamma-aminobutyric acid (GABA) is involved in the proliferation, differentiation, and migration of several kinds of cells including cancer cells. GABA is synthesized predominantly from glutamate by glutamate decarboxylase and exerts its effects via ionotropic GABA(A) receptors and/or metabotropic GABA(B) receptors. In this review, the current state of knowledge regarding the role of the GABAergic system in peripheral nonneuronal cell proliferation is described, and recent advances in elucidation of the mechanisms leading to cell proliferation are discussed.

Animals↗

PROPELLER diffusion-weighted magnetic resonance imaging of acute spinal epidural hematoma.

We present the case of an 86-year-old female with spontaneous spinal epidural hematoma. Although T1- and T2-weighted images showed the dilated posterior epidural space at the cervical spine, this finding was non-specific on conventional magnetic resonance imaging obtained 15 h after the onset of symptoms. Diffusion-weighted imaging with the use of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER), which clearly revealed the high intensity hematoma, was useful for detection and diagnosis of acute spinal epidural hematoma.

Acute Disease↗

Plasma treatment increased shear bond strength between heat cured acrylic resin and self-curing acrylic resin.

Self-curing acrylic resin is generally used for the repair of a fractured denture base. However, re-fracture of the repaired denture base resin often occurs because of poor bonding strength between the base resin and self-curing repair resin. The effect of plasma treatment on the shear bond strength between heat cured acrylic resin and the self-cured acrylic was examined. It was revealed that plasma irradiation is effective in increasing the shear bond strength. Plasma irradiation does not cause environmental pollution, as it does not require chemicals. It is a useful method to increase adhesive strength between heat cured acrylic resin and self-curing acrylic resin.

Acrylic Resins↗

Histopathological changes in the tissues under a denture base in experimental osteoporosis with a non-pressure covering or bearing continuous pressure.

In this study, the experimental denture base on the hard palate of the molar region of osteoporotic rats was designed to cover without any mechanical pressure or to load continuous pressure (0.5, 1.5 or 3.4 kPa). Experimental osteoporosis was induced by ovariectomy and feeding on a low calcium diet. Histopathological changes induced by non-pressure covering or continuous pressure in the tissues under the experimental denture bases were examined. Regarding the histological changes induced by continuous pressure, this was evaluated in relation to the time course of the intensity of the continuous pressure. In the tissues under the denture base in osteoporotic condition with non-pressure covering, no histopathological changes caused by non-pressure covering were observed except for a transient slight proliferative reaction in the epithelial ridge. The following histopathological changes were observed in the tissues under the denture base in the osteoporotic condition bearing continuous pressure; (i) bone resorption was induced on the periosteal surface (Ps) in the osteoporotic-3.4 kPa group, and on the pressure side of the endocortical surface (p-Ec) in the osteoporotic-1.5 and -3.4 kPa group, (ii) the appearance of osteoclasts on the p-Ec in the osteoporotic-3.4 kPa group was earlier than that on the Ps in a same group, (iii) bone resorption on the pressure side of the Ec in the osteoporotic-3.4 kPa group manifested at the earlier stage than that in the osteoporotic-1.5 kPa group, (iv) bone formation following bone resorption on the p-Ec was observed more markedly than that on the Ps and (v) histopathological changes in the tissues under the denture base in experimental osteoporosis bearing continuous pressure had an intimate relationship with the initial intensity and the time course of continuous pressure.

Animals↗

A single oral administration of conjugated linoleic acid enhanced energy metabolism in mice.

We investigated the effect of a single oral administration of conjugated linoleic acid (CLA) on energy metabolism in mice. Male Std ddY mice were orally administered CLA (5 mL/kg weight) or linoleic acid (5 mL/kg weight) (both solutions at concentrations of 73.5%) as a control. Oxygen consumption was significantly greater in the CLA-administered mice than in the control mice. Respiratory quotient was slightly lower in the CLA-adminis-tered mice than in the control mice. We calculated fat and carbohydrate oxidation from oxygen consumption and respiratory quotient. Fat oxidation in the CLA-administered mice was significantly higher than in the control mice, and there was no difference in carbohydrate oxidation. Serum concentrations of noradrenalin and adrenalin in the CLA administered mice were significantly higher than in the control mice. These results suggested that CLA enhanced sympathetic nervous activity and energy metabolism.

Administration, Oral↗

Administration of capsiate, a non-pungent capsaicin analog, promotes energy metabolism and suppresses body fat accumulation in mice.

We investigated the effects of a single oral administration of capsiate, which is found in the fruits of a non-pungent cultivar of pepper, CH-19 Sweet, and has the same structure as capsaicin except for replacement of NH by O in the alkyl chain, on the thermogenesis and fat accumulation in mice. The oxygen consumption and serum adrenalin concentration were higher in both the capsaicin (10 mg/kg-body weight) and capsiate (10 mg/kg-body weight) groups than those in the control group. We also examined the effects of 2 weeks of administration of capsaicin and capsiate on body fat accumulation. Eevery day for 2 weeks administration of capsiate (10, 50 mg/kg-body weight/day) markedly suppressed body fat accumulation as well as capsaicin (10 mg/kg-body weight/day). These results suggest that capsiate promotes energy metabolism and suppresses body fat accumulation as does capsaicin.

Adipose Tissue↗

Mercury contamination in the Yatsushiro Sea, south-western Japan: spatial variations of mercury in sediment.

Mercury-contaminated effluent was discharged into Minamata Bay from a chemical plant over a 20-year period until 1965 (from 1958 to 1959, effluent was discharged into Minamata River), causing Minamata disease. In an effort to characterize the extent of the contamination in the Yatsushiro Sea, the vertical and horizontal distributions of mercury in sediment were investigated. Sediment was sampled at 62 locations in the southern part of the sea from 4 to 6 March 1996. In the lower layers of the long cores of sediment, the total amount of mercury was at a relatively uniform low concentration. We interpret these low values to represent the background concentration absent of anthropogenic influence. The background value thus estimated for the Yatsushiro Sea was 0.059 +/- 0.013 mg kg(-1) (mean +/- S.D., n = 51). The highest concentration in each sample ranged from 0.086 to 3.46 mg kg(-1) (mean, 0.57 mg kg(-1)). The higher values were obtained at stations near Minamata Bay and the Minamata River (the sources of the pollution). Concentrations decreased with distance from the source. An inspection of the vertical profiles of mercury concentration in cores suggested that the deposited mercury had not been fixed in sediment but had been transported, despite 30 years having past since the last discharge of contaminated effluent. At nine stations, extractable inorganic and organic mercury concentrations were determined differentially. Inorganic mercury is the predominant species in sediment and organic mercury comprising approximately 1% of the total.

Chemical Industry↗

HRTEM image contrast of short range order in Ni4Mo

The high resolution transmission electron microscope (HRTEM) imaging of short range order (SRO) in Ni4Mo was investigated by means of multi-slice image simulations. The HRTEM images of Ni4Mo exhibit locally bright dot patterns corresponding to the [001] projections of the N2M2-type (chalcopyrite-like) structure. The multi-slice simulations revealed that the N2M2 patterns are rationalized as the projection patterns of the SRO structure which consists of subunit cell clusters of D1a, D022 and Pt2Mo structures. The N2M2-type image contrast appears when both the fundamental fcc lattice reflections and the 1 1/2 0 diffuse scattering of SRO contribute enough to imaging. This suggests that a good coincidence in intensity distribution between the Fourier power spectra of HRTEM images and the electron diffraction patterns is one of the conditions for the image contrast of SRO to be interpreted in terms of the projection contrast.

Journal Article↗

Ordering process of Cu3Pt from short-range order state studied by in-situ TEM observation

The state of short-range order (SRO) and the ordering process in Cu3Pt have been studied by the in-situ transmission electron microscope observation method. In order to detect weak diffraction-patterns and weak image-contrasts, an imaging plate system and/or digital-process of video-recorded signals were applied. It is confirmed that above the critical temperature for ordering, Tc, the alloy shows diffuse scattering in its electron diffraction pattern. The appearance of the diffuse scattering indicates that the "disordered" Cu3Pt (designated as A1) has an SRO-state in thermoequilibrium. Dark field images taken by using the diffuse scattering shows a fine dot-contrast, which indicates the presence of "microdomains". The dot-contrast is flickering at higher temperatures, but the rate of flickering decreases with falling temperature and finally stops before reaching Tc. On further decreasing temperature, some of the microdomains grow up to large domains of the long period superstructure (L12-s) phase. This indicates that the transformation to L12-s via SRO proceeds without a process of nucleation even though the transformation is of a first-order.

Journal Article↗

Gradual tilting of crystallographic orientation and configuration of dislocations in GaN selectively grown by vapour phase epitaxy methods

Cross-sectional transmission electron microscope (TEM) observation was performed for selectively grown gallium nitride (GaN) in order to examine the dependence of GaN microstructure on the growth conditions. The GaN films were grown by hydride vapour phase epitaxy (HVPE) or metalorganic vapour phase epitaxy (MOVPE) on GaN covered with a patterned mask. Thin foil specimens for TEM observation were prepared with focused ion beam (FIB) machining apparatus. It was demonstrated that the c-axis of GaN grown over the terrace of the mask tilts towards the centre of the terrace when the GaN is grown in a carrier gas of N2. The wider terrace results in a larger tilting angle if other growth conditions are identical. The tilting is attributed to 'horizontal dislocations' (HDs) generated during the overgrowth of GaN on the mask terrace. The HDs in HVPE-GaN have a semi-loop shape and are tangled with one another, while those in MOVPE-GaN are straight and lined up to form low-angle grain boundaries.

Journal Article↗

Estimation of the lethal toluene concentration from the accidental death of painting workers.

To determine the potentially lethal level of thinner concentration in the air, we measured the concentration of toluene in the blood and others of three patients who suffered severe acute thinner intoxication between 4 January 1996 and 21 April 1997 in Ube city. The concentration of toluene in blood were 30.2 mg/L in died patient, and 13.7 mg/L and 17.5 mg/L in recovered patients, respectively. By extrapolation from the results of our previous toxicokinetic research on toluene poisoning in anesthetized dogs, the fatal concentration of toluene was estimated to be approximately 1800 to 2000 ppm for 1-hour exposure.

Accidents, Occupational↗

Effects of mitogen-activated protein kinase inhibitors or phosphodiesterase inhibitors on interleukin-1-induced cytokines production in synovium-derived cells.

The effects of mitogen-activated protein (MAP) kinase inhibitors or phosphodiesterase (PDE) inhibitors on interleukin (IL)-1-induced cytokines production in synovium-derived cells were investigated. Human synoviocyte (HS) or synovial sarcoma (SW982) stimulated by IL-1beta (100 ng/ml) produced various cytokines including IL-6, IL-8, GROalpha, VEGF, basic FGF and tumor necrosis factor alpha (TNFalpha) in vitro. SB202190 or SB203580, an inhibitor of p38 MAP kinase, inhibited all cytokines production in both cells. PD98059, an inhibitor of MAP kinase kinase (MEK), inhibited IL-6, IL-8 and basic FGF production in HS and all cytokines production except basic FGF in SW982. However, many of its effects were weaker than those of SB202190 or SB203580. Quazinone, an inhibitor of cyclic GMP-inhibited PDE, scarcely affected cytokines production in both cells. Rolipram or R0201724, an inhibitor of cyclic AMP-specific PDE, inhibited IL-8 and basic FGF production in HS and TNFalpha production in SW982, however, it enhanced the other cytokines production in SW982. These results suggest that the activation of MAP kinase cascade may be important for IL-1-induced cytokines production in synovium-derived cells. On the other hand, the role of cyclic AMP may be dependent on cell and cytokine types.

4-(3-Butoxy-4-methoxybenzyl)-2-imidazolidinone↗

Involvement of leukotriene B4 in arthritis models.

We investigated the role of leukotriene B4 (LTB4) in murine arthritis models using a leukotriene A4 (LTA4) hydrolase inhibitor, SA6541. SA6541 inhibited the severity of collagen-induced arthritis and muramyl dipeptide (MDP)-induced hyperproliferation of synovial cells in vivo. SA6541 also inhibited LTA4-induced hyperproliferation of synovial stromal cells in vitro. These results suggest that LTB4 may play an important role in arthritis models.

Acetylmuramyl-Alanyl-Isoglutamine↗

A new quadruple therapy for the eradication of Helicobacter pylori. Effect of pretreatment with omeprazole on the cure rate.

To elucidate whether pretreatment with omeprazole decreases the cure rate of Helicobacter pylori infection with a new quadruple therapy, and thus, whether this pretreatment should not be used in clinical practice, we conducted a randomized trial. Ninety patients with chronic peptic ulcer disease and nonulcer dyspepsia, with biopsy-proven H. pylori infection were randomly assigned to the two following regimens: Group 1 (n = 45) received omeprazole 20 mg once daily for 2 weeks (days 1-14), and 500 mg amoxicillin granules and 250 mg metronidazole thrice daily, and roxithromycin 150 mg twice daily for 1 week (days 8-14), Group 2 (n = 45) received the same antibiotic treatment as group 1 for 1 week (days 1-7), in addition to omeprazole treatment for 2 weeks (days 1-14). Four weeks after the treatment ended, endoscopy was repeated, with two biopsy specimens each taken from the antrum and the corpus (total of four specimens) for a urease test, histological analysis, and culture to establish cure of infection. A patient was regarded as cured only if all three methods gave negative results for H. pylori. In the intention-to-treat analysis, 42 of 45 patients (93.3%; 95% confidence intervals [CI], 81.7%-98.6%) in group 1 were cured compared with 43 of 45 patients (95.6%; 95% CI, 84.9%-99.5%) in group 2. In the per-protocol analysis, the corresponding figures were 42/44 (95.5%; 95% CI 84.5%-99.4%) and 43/44 (97.7%; 95% CI, 88.0%-99.9%). There were no significant differences in the cure rate between the two groups on either analysis. All patients, except for one who had an allergic reaction, completed the treatment regimens. Fifty to sixty percent of the patients had no side effects while the rest had mild to moderate side effects. The new quadruple therapy consisting of omeprazole, amoxicillin, metronidazole, and roxithromycin appears suitable for use in clinical practice, as the cure rate was 95% and no severe side effects were observed. Pretreatment with omeprazole did not reduce the cure rate for this new quadruple therapy.

Adult↗

Arcuate keratotomy to treat corneal astigmatism after cataract surgery: a prospective evaluation of predictability and effectiveness.

OBJECTIVE: Although several nomograms are available for the incisional keratotomy to correct naturally occurring astigmatism, astigmatic keratotomy in eyes after cataract surgery has not been well analyzed. The predictability and effectiveness of arcuate keratotomy in pseudophakic eyes were studied. DESIGN: A prospective, multicenter study. PARTICIPANTS: One hundred four eyes of 86 patients with residual corneal astigmatism of 1.5 diopters (D) or more after cataract surgery were examined. INTERVENTION: Arcuate keratotomy was performed in nine centers by nine surgeons. MAIN OUTCOME MEASURES: The amount of astigmatic correction was calculated using the vector analysis of preoperative and 6-month postoperative refractive cylinder results. RESULTS: Multiple regression analysis showed that optical zone size, number of incisions, and incision length had significant correlations with the amount of astigmatic correction. The regression equation was expressed as effects = (-0.643 x optical zone size) + (0.998 x incision number) + (0.057 x incision length) + 2.356. The parameter of predictability (r2: 35%) was lower than that reported for congenital astigmatism (48 to approximately 56%). A new nomogram was derived based on the multiple regression equation. CONCLUSIONS: Astigmatic keratotomy in pseudophakic eyes is less predictable than that in eyes with idiopathic astigmatism, but the procedure is sufficiently effective in reducing the residual astigmatism after cataract surgery. Individual nomograms are necessary for astigmatic keratotomy in eyes with naturally occurring and postsurgical astigmatism.

Aged↗