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K Onuma

Publications and source records attributed to K Onuma.

At least 19 recordsLinked to original sources
PubMed2002

In situ study of partially crystallized Bioglass and hydroxylapatite in vitro bioactivity using atomic force microscopy.

The present work investigates, in situ, the in vitro bioactivity of partially crystallized 45S5 Bioglass (BG) as a function of immersion time in a simulated body fluid (SBF) using atomic force microscopy (AFM). The results obtained for the crystallized BG were compared to those of hydroxyapatite c- and a-faces. The calcium phosphate layer grows on the crystallized 45S5 B by multiple two-dimensional nucleation and fusion of these two-dimensional islands, which is essentially the same mode as for the hydroxyapatite c-face. The surface of the crystallized 45S5 BG was almost fully covered with a dense and compact calcium phosphate layer after 24 h. The calcium phosphate formation on the crystallized BG arises from a low surface energy of the surface layer and/or an effect of the layer to lower the resistance when the growth units of calcium phosphate incorporate into the growing island. These results indicate that the crystallized 45S5 BG is suitable to be used as a filler for polymeric matrix bioactive composites, as it maintains a high bioactivity associated with a stiffer behavior (as compared to standard BG).

Biocompatible Materials↗
PubMed2001

Denaturation and aggregation of hen egg lysozyme in aqueous ethanol solution studied by dynamic light scattering.

We applied dynamic light scattering technique on the model system of hen egg lysozyme in salt-free aqueous ethanol solution to study the mechanism of denaturation and aggregation of protein. At low ethanol concentration [0-63% (v/v)], the fast relaxation mode was observed, which was caused by lysozyme molecules in the solution interacting with each other with strong repulsive electrostatic force. At 45 and 63% (v/v) ethanol, the slow relaxation mode was also observed, which showed translational diffusive nature, similar to that observed in salt-free polyelectrolyte solution. At 72 or 81% (v/v) ethanol, the slow mode disappeared, leaving only the fast mode. However, the mutual diffusion coefficients obtained from the fast mode at 72 and 81% (v/v) ethanol decreased by about one order of magnitude compared with those from the fast mode at 0-63% (v/v). The reported alcohol-induced conformational transformation of lysozyme molecules at >60% (v/v) ethanol from their native structure to an alpha-helix-rich structure might cause such drastic decrease in the mutual diffusion coefficients. At the highest ethanol concentration of 90% (v/v), the slow mode reappeared, and its relaxation rate was decreasing with elapsed time, which is possibly due to the growth of aggregates of lysozyme molecules. X-ray diffraction results suggested that the intermolecular beta-sheet formation caused the aggregation. Thus, our results indicated that the change in molecular structure of lysozyme closely relates to the diffusion of molecules and their aggregation.

Animals↗
PubMed2001

Calcium phosphate clusters.

The potential energy surfaces associated with [Ca3(PO4)2n clusters are analyzed in detail using ab initio calculations for n ranging from one to four. Considering separated clusters, energy criteria favor the so-called Posner's cluster Ca9(PO4)6, which is the core of the actual structural model of amorphous calcium phosphate. This is rationalized through the existence of a distinct CaO bonding pattern in this cluster. Considering aggregated clusters as a possible model for amorphous calcium phosphate, the aggregation of Ca3(PO4)2 clusters appears as an alternative to Posner's hypothesis.

Biocompatible Materials↗
PubMed2001

Pigmented intraosseous odontogenic carcinoma of the maxilla: a pediatric case report and differential diagnosis.

We report a pigmented intraosseous odontogenic carcinoma of the maxilla occurring in a 6-year-old Japanese boy. Grossly, the tumor showed solid, gray-yellow, and markedly pigmented appearance. Histology showed neoplastic growths of atypical epithelial cells that occasionally contained melanin pigments. Melanocytes with dendritic processes were often found in the tumor cell clusters, and solitary or aggregated melanophages were scattered within the dense fibrovascular stroma. The tumor cells were diffusely positive for cytokeratins and epithelial membrane antigen, and focally positive for vimentin, neuron specific enolase, neurofilament protein, carcinoembryonic antigen, and amelogenin. Ultrastructural studies showed well-developed intercellular junctions, mainly desmosomes, and glycogen particles. In addition, some tumor cells contained melanosomes and/or a few neurosecretory granules. We consider that the present tumor suggests a close association of ectoderm, mesenchyma, and neuroectoderm in embryogenesis of the tooth, and can raise a diagnostic confusion with melanotic neuroectodermal tumor.

Antigens, Neoplasm↗
PubMed2001

Parallel induction of nitric oxide and tetrahydrobiopterin synthesis in alveolar macrophages.

BACKGROUND: Nitric oxide (NO) and an essential cofactor for both constitutive and inducible NO synthase (NOS) activity, tetrahydrobiopterin (6R-L-erythro-1',2'-dihydroxypropyl-2-amino-4-hydroxy-5,6,7,8-tetrahydropteridine; BH4), are thought to be important modulators of function in normal and inflamed airways. However, the exact pathologic roles of NO and BH4 remain obscure. Even less is known about the effects of cytokines on alveolar macrophages. OBJECTIVE: This study was designed to determine whether NO and BH4 are induced by cytokines in mouse alveolar macrophages and to investigate whether NO synthesis is affected by changes in intracellular BH4 levels in alveolar macrophages. METHODS: We compared the induction by lipopolysaccharide (LPS), interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and interleukin-2 (IL-2) of NO production and BH4 synthesis in alveolar macrophages. To determine whether NO synthesis is affected by changes in intracellular BH4 levels in alveolar macrophages, we used inhibitors of BH4 biosynthesis. RESULTS: Activation of alveolar macrophages induced parallel increases in NO and intracellular BH4 levels, although induction of the latter appears to be somewhat more sensitive than that of the latter to diverse cytokines. Inducible NO production in alveolar macrophages was blocked by inhibitors of BH4 biosynthesis. IL-2, an important component of the immunomodulatory system, was only a weak activator of alveolar macrophages by itself but potently synergized with IFN-gamma to stimulate the production of both NO and BH4. CONCLUSION: Our results suggest that BH4 synthesis in alveolar macrophages is a potential target for therapeutic intervention in airway inflammatory diseases, such as asthma, cystic fibrosis, and acute bronchial infections whose pathology may be mediated by overproduction of NO.

Animals↗
PubMed2001

Correlation between the airway branching patterns and the heterogeneous distribution of the lesions in bleomycin-injured mouse lung: a 3-D morphometric study.

The possible roles of airway branching patterns on the pathogenesis of lung diseases, especially on the heterogeneous distribution of the lesions, were examined through three-dimensional (3-D) morphometric analysis of a mouse lung injury, induced by bleomycin. On serial sections of a mouse lung damaged by subcutaneous injection of bleomycin, we performed a computer-assisted reconstruction of the lung for visualizing the relation of airways with the distribution of the lesions, and defined the features of bronchial routes to each lesion by four parameters: LTB; the distance from the hilum, Ng; generation numbers, RD(min); irregularity of airway branching, and thetaTB; the grade of airway recurrence. Among these four parameters, only thetaTB was found to correlate with the severity of lesions (p < 0.05 by an ANOVA test), which was proved by a posthoc test (p < 0.0001). These results showing the acini supplied by recurrent branches are more prone to be damaged than those by non-recurrent branches suggest that branching patterns may underlie the heterogeneous distribution of lesions in diffuse interstitial lung diseases.

Algorithms↗
PubMed2001

Irregularity of airway branching in a mouse bronchial tree: a 3-D morphometric study.

Limited information on the degree of irregularity of branching patterns of a bronchial tree may obscure the cause of heterogeneous distribution of the lesions in a variety of lung diseases. We reconstructed three dimensional (3-D) images from hilum to terminal bronchioles of a mouse lung, and defined the irregularity of airway branching by diameter-based morphometric analysis. The relative diameter ratios of a daughter to the parent branch (D1/D0) and those of a minor to major daughter branches (D1/D2) were calculated, and irregular dichotomies were found to be distributed in 48% of bifurcations. D1/D0 is well correlated with D1/D2, and is proved to indicate regular and irregular branching, as well as D1/D2. Irregular branches with D1/D0 smaller than 0.4 correspond to typical lateral branches, taking off from major bronchi. Our novel 3-D morphometric analysis showed the first portrayal of the 3-D structures of mouse bronchial airways, which provides a quantitative description of branching patterns leading to the correlation with distribution of lesions in the diseased lung.

Algorithms↗
PubMed2000

Cigarette smoking, CYP1A1 MspI and GSTM1 genotypes, and colorectal adenomas.

Cigarette smoking has been related to increased risk of colorectal adenomas, but the underlying mechanisms are unknown. Genetic polymorphisms are known for enzymes involved in the activation of polycyclic aromatic hydrocarbons and other tobacco-related carcinogens. Polycyclic aromatic hydrocarbons are activated by cytochrome P4501A1 (CYP1A1) and detoxified by glutathione S-transferases. We investigated the relation of CYP1A1 MspI and GSTM1 genotypes to the risk of colorectal adenomas with special reference to interaction with cigarette smoking among 205 cases of colorectal adenomas and 220 controls with normal total colonoscopy in a male Japanese population. Cigarette smoking was strongly associated with increased risk of colorectal adenomas. Overall, neither the CYP1A1 MspI genotype nor the GSTM1 genotype was related to colorectal adenomas. A significant trend for increased risk of colorectal adenomas associated with smoking was observed for each of the CYP1A1 MspI genotypes, and the increasing trends did not differ by MspI genotype. The positive association between smoking and colorectal adenomas did not vary much with GSTM1 genotypes. Among former and current smokers, adenoma risk did not differ according to the combination of CYP1A1 MspI and GSTM1 genotypes. CYP1A1 MspI and GSTM1 genotypes do not seem to modify the risk of colorectal adenomas associated with cigarette smoking.

Adenoma↗
PubMed2000

In Situ Observation of Growth Process of alpha-L-Glutamic Acid with Atomic Force Microscopy.

The growth kinetics of the (111) and (001) faces of an alpha-L-glutamic acid crystal was investigated from the measurements of the growth rates, coupling with in situ surface observation using atomic force microscopy (AFM). The data of the growth rates were examined by applying the theoretical equations of the BCF and NaN models. The results indicate that the growth mechanism is not due to the screw dislocation but to the two-dimensional nucleation, i.e., the NaN model. It was confirmed by AFM observation that both the (111) and (001) faces grew with the "nucleus above nucleus" (NaN) mechanism. However, the difference of the two-dimensional nucleation behavior was observed between the faces. The growing surface of the (111) face was also observed in the presence of L-phenylaline (L-Phe) and the pinning effect by L-Phe on the growing step on the (111) face was confirmed. This result supports the mechanism of the additive effect, which was proposed previously. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Methylenetetrahydrofolate reductase polymorphism and risk of colorectal adenomas.

A homozygous mutation at bp 677 in the gene for the methylenetetrahydrofolate reductase (MTHFR) was previously shown to be associated with a decreased risk of colorectal cancer. We examined the relation between the MTHFR genetic polymorphism and risk of colorectal adenoma in Japanese men using 205 cases of colorectal adenomas and 220 controls of normal total colonoscopy. The homozygous mutation was not measurably associated with colorectal adenomas. The findings corroborate the lack of an association between the MTHFR genotype and colorectal adenomas, but do not deny the possibility that the genotype may be involved in the late stage of colorectal carcinogenesis.

Adenoma↗
PubMed2000

Efficacy of leukotriene receptor antagonist in bronchial hyperresponsiveness and hypersensitivity to analgesic in aspirin-intolerant asthma.

BACKGROUND: Albeit its exact pathogenesis is still ambiguous; aspirin-intolerant asthma is one of several types of asthma for which antileukotriene therapy is useful, because it is widely accepted that bronchial over-production of leukotrienes may be involved in its pathogenesis. Pranlukast (8-[p-(4-phenylbutyloxy) benzol] amino-2-(tetrazol-5-yl)-4-oxo-4H-1-benzopyran hemihydrate), a selective cysteinyl leukotriene receptor antagonist, is now widely used in the treatment of asthma. OBJECTIVE: This study was designed to investigate the protective effect of pranlukast on airway sensitivity to sulpyrine provocation testing, bronchial responsiveness to methacholine provocation testing, and to investigate whether this protective activity is associated with a reduction in aspirin-induced excretion of urinary LTE4 (uLTE4), a marker of the cysteinyl leukotriene (LT) overproduction that participates in the pathogenesis of aspirin-induced asthma. METHODS: We assessed the effects of pretreatment with pranlukast on bronchoconstriction precipitated by inhalation of methacholine and sulpyrine in 16 adult patients with mild or moderate aspirin-intolerant asthma; those who were in stable clinical condition and were hypersensitive to sulpyrine provocation testing were allocated to this study. A double-blind, randomized, crossover design was used. uLTE4 was measured using combined reverse-phase high-performance liquid chromatography (rp-HPLC)/enzyme immunoassay. RESULTS: Pranlukast protected against analgesic-induced bronchoconstriction through mechanisms that were not related to the bronchodilator property, but were related to the improvement both of bronchial hyperresponsiveness and hypersensitivity to analgesic (P < 0.005 and P < 0.0001). Pranlukast showed little effect on excretion of uLTE4. CONCLUSION: These results support the hypothesis that cysteinyl leukotriene is one of the most important components in the pathogenesis of aspirin-intolerant asthma. Pranlukast improves not only hypersensitivity to analgesic, but also bronchial hyperresponsiveness in aspirin-intolerant asthma. It is also possible that pranlukast has another anti-asthmatic effect besides that of a leukotriene receptor antagonist.

Adult↗
PubMed2000

Effect of pranlukast on bronchial inflammation in patients with asthma.

BACKGROUND: Pranlukast (8-[p-(4-phenylbutyloxy) benzol] amino-2-[tetrazol-5-yl]-4-oxo-4H-1-benzopyran hemihydrate), a selective cysteinyl leukotriene receptor antagonist, has been reported to exhibit not only antileukotrine activity but also pharmacological activity including antieosinophilic effects. OBJECTIVE: This study was designed to investigate whether the antiasthmatic activity of pranlukast is associated with a reduction in eosinophilic inflammation. METHODS: A double-blind, randomized, crossover design was used. Subjects received 225 mg of pranlukast or placebo orally twice daily for 4 weeks and then, after a washout period of at least 4 weeks, crossed over to receive the alternative treatment. We assessed the effects of pretreatment with pranlukast on bronchoconstriction precipitated by inhalation of methacholine in 32 adult patients with mild or moderate bronchial asthma; those who were in stable clinical condition were allocated to this study. Blood and sputum samples were taken the morning of the methacholine provocation test. Eosinophil counts and measurement of eosinophilic cationic protein (ECP) were performed. RESULTS: After the 4 weeks of treatment with pranlukast, patients' symptoms, blood eosinophils, serum ECP, sputum eosinophils, and sputum ECP were significantly decreased. Furthermore, values of PC20-methacholine significantly improved in the treatment with pranlukast. CONCLUSION: Our results suggest that pranlukast has an anti-inflammatory effect on bronchial eosinophilic infiltration. This study raises further interesting therapeutic possibilities and argues for further trials of new approaches to the treatment of bronchial asthma.

Adult↗
PubMed2000

Analysis of physician ability in the measurement of pulsus paradoxus by sphygmomanometry.

CONTEXT: Measurement of pulsus paradoxus (PP) is one of several measures previously advocated in the National Heart, Lung, and Blood Institute asthma management guidelines: a pulsus of > 12 mm Hg warranted hospital admission. It is one of only a few measures that is not effort dependent and therefore important in the evaluation of patients with asthma. OBJECTIVE: Determination of physician accuracy in measuring PP. DESIGN: A model of induced PP in a trained healthy subject without respiratory disease was constructed with a fixed inspiratory resistance with measurement of inspiratory air pressure and beat-to-beat BP noninvasively. SETTING: Laboratory. PARTICIPANTS: Attending physicians from emergency medicine and critical care disciplines who served as consecutive examiners of the trained reference subject generating known PP. INTERVENTIONS: A total of 19 attending physicians were assessed for ability in measuring PP by sphygmomanometry and by palpation. The reference subject generated 4 degrees of PP sequentially, with each examiner blinded to the value of negative inspiratory pressure and PP. Examiners first assessed PP qualitatively by palpation, followed by its measurement within 2 min. MAIN OUTCOME MEASURE: Proximity of physician-measured PP (PPm) to true PP (PPt). RESULTS: At inspiratory pressures of - 10, - 15, - 20, and - 25 mm Hg, PPt was 13.7, 16.2, 19.1, and 20.7 mm Hg, respectively (F = 14.8, p < 0. 0001; analysis of variance [ANOVA]). At the same pressures, PPm was 13.1, 17.5, 17.7, and 18.0 mm Hg (p > 0.10; ANOVA). Linear regression of PPm against PPt for each examiner revealed a slope (SE) of 0.53 (0.23), and not a 1:1 relationship. CONCLUSIONS: Past and present guidelines do not account for the challenges in measuring PP, especially in tachypneic patients. Sphygmomanometric determination of PP should be augmented by new aids developed through technological innovation.

Adult↗
PubMed1999

Amalgam allergy associated with exacerbation of aspirin-intolerant asthma.

BACKGROUND: Aspirin-intolerant asthma can be induced not only by acidic analgesics (including acetylsalicylic acid), which effectively inhibit cyclo-oxygenase, but also by cross-reactivity with paraben, and other chemical additives. OBJECTIVE: We examined whether amalgam allergy is involved in the pathogenesis of a aspirin-intolerant asthma. METHODS: We present the first case of aspirin-intolerant asthma that improved after the removal of dental amalgam. In addition, we performed both the methacholine provocation testing and sulpyrine provocation testing before and after the removal of dental amalgam. RESULTS: In addition, the methacholine concentration causing a 20% fall in FEV1 in provocation tests rose significantly, though hypersensitivity to analgesics evaluated with sulpyrine provocation testing did not decrease. These results suggest that amalgam sensitization is involved in bronchial hyperresponsiveness in aspirin-intolerant asthma. CONCLUSION: Sensitivity to amalgam may cause exacerbation of aspirin-intolerant asthma in some patients. To the best of our knowledge, this is the first case report of amalgam allergy associated with aspirin-intolerant asthma.

Adult↗
PubMed1999

Obesity, weight gain and risk of colon adenomas in Japanese men.

Obesity has been related to increased risk of colon cancer or adenomas, but the epidemiologic findings are not entirely consistent. We examined the relation of not only body mass index (BMI) but also waist-to-hip ratio (WHR) and weight gain to colon adenoma risk in men who received a preretirement health examination at the Japan Self Defense Forces (SDF) Fukuoka and Kumamoto Hospitals during the period from 1995 to 1996. In the series of 803 men at age 47-55 years, 189 cases of colon adenomas and 226 controls with normal total colonoscopy were identified. Weight at 10 years before was ascertained by referring to the recorded data. After allowance for hospital, rank in the SDF, smoking and alcohol use, weight gain over the past 10 years was significantly associated with increased risk of colon adenomas (odds ratio for > or = 6 kg versus < or =-2 kg = 2.2; 95% confidence interval 1.0-4.8). High BMI and high WHR were each associated with increased risk, but only WHR was related to the risk independently of weight gain. In particular, weight gain accompanied with a high WHR was associated with a significant increase in the risk. Men with high physical activity tended to have lower risk. Associations with obesity-related variables and physical activity were not materially differential as regards the location and size of adenoma. The findings indicate that weight gain in middle age leading to abdominal obesity increases the risk of colon adenomas, and consequently of colon cancer.

Adenoma↗