Biomedical subjects

S Sakai

Publications and source records attributed to S Sakai.

At least 55 records · Page 3Linked to original sources

PubMed2001

Isolation of a MADS-box gene (ERAF17) and correlation of its expression with the induction of formation of female flowers by ethylene in cucumber plants (Cucumis sativus L.).

Ethylene regulates sex expression in cucumber (Cucumis sativus L.) plants. When the apices of monoecious cucumber seedlings (cv. Shimoshirazu-jibai) were treated with the ethylene-releasing compound, ethephon, female flowers were induced at the nodes. To clarify the action of ethylene in the regulation of sex expression, we attempted to isolate genes whose expression changed during induction of the formation of female flowers at the apices of these cucumber plants upon treatment with ethephon. Using the differential-display method, we identified 20 clones (#1 to #20) that reflected differences in the accumulation of transcripts in apices treated or not treated with ethephon. Sequence analysis of cDNA fragments revealed that the cDNA #17 had the sequence of a MADS-box gene. We isolated the full-length cDNA and showed that it included both a MADS box and a K box, and the corresponding gene was designated ERAF17. We examined the expression of ERAF17 in the apices of cv. Shimoshirazu-jibai and in those of a gynoecious cultivar (Rensei). In these cultivars, the timing and levels of expression of the ERAF17 transcript were correlated with the development of female flowers. Induction of the synthesis of the ERAF17 transcript by ethephon occurred within 4 h of the start of treatment and continued for 4 days at least. Expression of ERAF17 at apices was localized in the floral buds of the gynoecious cultivar, and expression was maintained in female flowers thorough their development. Our results suggest that the induction of the formation of female flowers by ethylene might be regulated by the expression of ERAF17 in floral buds at the apices of cucumber plants and that expression of this gene might also be involved in the development of female flowers.

Amino Acid Sequence↗

PubMed2001

Relapse patterns of localized non-Hodgkin's lymphoma of the head and neck after clinical remission: results of a strict follow-up procedure.

BACKGROUND: No effective follow-up strategy for non-Hodgkin's lymphoma (NHL) has been identified to date. The aim of this study was to assess the value of a strict follow-up procedure in patients with NHL after they showed clinical remission. METHODS: One hundred and twenty-one patients with localized NHL of the head and neck who had achieved clinical remission after radiation therapy and/or chemotherapy were followed with a strict follow-up strategy (consisting of a schedule of frequent office visits, imaging studies, and blood tests, even if the patient was asymptomatic). RESULTS: Thirty-nine patients relapsed after remission. Twenty-two (56.4%) of the relapses were associated with symptoms. In the 17 patients with asymptomatic relapses (43.6%), an abnormal physical examination result initially indicated relapse in 10 patients. The other tests that initially indicated relapse included scheduled computed tomography scans (3 patients), scheduled gallium scans (2 patients), and serum lactate dehydrogenase levels (2 patients). According to the Ann Arbor stage at relapse, 72.7% of the patients with symptomatic relapses were stage III or IV, while 70.6% of the patients with asymptomatic relapses were stage I or II. CONCLUSIONS: These results indicate that a strict follow-up procedure is effective in detecting asymptomatic relapses, which generally involve a smaller tumor load than symptomatic relapses.

Adult↗

PubMed2001

Determinants of masticatory performance in dentate adults.

Masticatory performance results from a complex interplay of direct and indirect effects, yet most studies employ univariate models. This study tested a multivariate model of masticatory performance for dentate subjects. Explanatory variables included number of functional tooth units, bite force, sex, age, masseter cross-sectional area, presence of temporomandibular disorders, and presence of diabetes mellitus. The population-based sample consisted of 631 dentate subjects aged 37-80 years. Covariance structure analysis showed that 68% of the variability in masticatory performance could be explained by the combined effects of the explanatory variables. Age and sex did not show a strong effect on masticatory performance, either directly or indirectly through masseter cross-sectional area, temporomandibular disorders, and bite force. Number of functional tooth units and bite force were confirmed as the key determinants of masticatory performance, which suggests that their maintenance may be of major importance for promoting healthful functional status.

Adult↗

PubMed2001

Synthesis and transport characterization of alginate/aminopropyl-silicate/alginate microcapsule: application to bioartificial pancreas.

To develop a novel type of immunoisolation membrane for a microcapsule-shaped bioartificial pancreas, we attempted to use a sol-gel synthesized silicate. An aminopropyl-silicate membrane derived from 3-aminopropyltrimethoxysilane and tetramethoxysilane was formed on Ca-alginate gel beads via electrostatic interaction. The positively charged amino groups remaining on the surface of the resultant gel beads were neutralized by immersion in an aqueous Na-alginate solution. From measurements of the partition coefficients and effective diffusivities of different substances to the gel beads, it was found that the aminopropyl-silicate membrane prepared under optimized composition of silicon alkoxide precursors successfully rejected gamma-globulin, giving good permeability to substances having a low molecular weight. Islets could be encapsulated within the newly developed microcapsules while retaining their ability to secrete insulin.

Alginates↗

PubMed2001

Pyridinyl imidazole inhibitor SB203580 activates p44/42 mitogen-activated protein kinase and induces the differentiation of human myeloid leukemia cells.

Various inhibitors of protein kinases regulate the growth and differentiation of human leukemic cell lines. The pyridinyl imidazole inhibitor SB203580 has been widely used to elucidate the role of p38 kinase in a wide array of biological systems. In the present investigation, we found that SB203580 effectively induced the granulocytic differentiation of human promyelocytic HL-60 cells. In addition to morphological differentiation, it also induced NBT-reduction, lysozyme activity and growth-inhibition. It also induced the differentiation of human myeloid leukemia HT93 and ML-1 cells, but not of other cell lines, such as NB4, U937, THP-1, K562 and HEL. This differentiation was not associated with the inhibition of p38 kinase activity, but was closely associated with the activation of extracellular signal-regulated kinase. These results demonstrate a new activity for this drug.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2001

Bioanalytical screening methods for dioxins and dioxin-like compounds a review of bioassay/biomarker technology.

Determination of environmental pollutants utilizing biodetectors such as bioassays, biomarkers, enzyme immunoassays (EIAs), or other bioanalytical tools is a continuously growing area. The present literature review describes the principles and advantages/limitations of several bioanalytical detection methods (BDMs) for the screening and diagnosis of dioxin and dioxin-like compounds. This study characterizes briefly the family of dioxin and dioxin-like compounds, discusses potential Ah receptor (AhR) ligands and cytochrome P-450 (CYP) 1A1-enzyme-inducing compounds. 'Milestones' in the development of BDMs are summarized and explained in detail for a number of bioanalytical tools that can be used to detect these classes of dioxin-like persistent bioaccumulative toxicants (PBTs). The design of a screening profile with a battery of bioassays/biomarkers coupled with the chemical analysis is evaluated. The relative potencies (REPs) to 2,3,7,8-TCDD for dioxin-like compounds are reviewed for various BDMs and the differences are noted.

Animals↗

PubMed2001

Combinatorial bio/chemical analysis of dioxin and dioxin-like compounds in waste recycling, feed/food, humans/wildlife and the environment.

The present review describes international activities using bioassays/biomarkers in combination with chemical analysis to measure the effects of dioxin and dioxin-like compounds (DLCs) in the environment. The above authors reviewed already the state-of-art bioanalytical detection methods (BDMs) for dioxins and DLCs [Environ Int (2001)]. The aim of this study will be to review applications of these bioassays/biomarkers to evaluate potential dioxins and DLCs. The present literature study lists relative potencies (REPs) of polyhalogenated dibenzo-p-dioxins and -furans (PXDD/Fs; X = Cl, Br, F), their thio analogues polychlorinated dibenzothiophenes (PCDTs) and thianthrens (PCTAs), polyhalogenated biphenyls (PXBs), polychlorinated naphthalenes (PCNs) and other Ah receptor agonists measured by several biodetectors (Tier 3 screening). The authors will discuss some examples of the applications of some of these biodetectors in biomonitoring programmes and recently occurred dioxin crisis in feed/food. The diagnosis of the biopotency of these pollutants in technical processes like thermally treated waste, waste water treatment, landfill leachate treatment, commercial PCB-mixtures, the release into the environment (soil, air and water) and the final intake into wildlife and humans will be reviewed.

Animal Feed↗

PubMed2001

Mechanical and structural characteristics of vulnerable plaques: analysis by coronary angioscopy and intravascular ultrasound.

OBJECTIVES: Mechanical and structural characteristics of vulnerable plaques were evaluated using coronary angioscopy and intravascular ultrasound. BACKGROUND: Mechanical stress and composition of plaques play an important role in plaque disruption. METHODS: Thirty-eight lesions in 38 patients were examined pre-interventionally. The plaques were classified as either yellow or white using coronary angioscopy. Intravascular ultrasound imaging was performed simultaneously with electrocardiographic and intracoronary pressure recordings to calculate distensibility index and stiffness beta. Moreover, the type of remodeling was classified. RESULTS: We identified 27 patients with yellow plaques and 11 patients with white plaques. Patients with yellow plaques presented acute coronary syndromes more frequently than stable angina (85% vs. 36%, p < 0.01). The distensibility index in yellow plaques was significantly greater than it was in white plaques (2.7 +/- 0.8 mm Hg(-1) vs. 0.7 +/- 0.8 mm Hg(-1), p < 0.0001), while stiffness beta for white plaques was significantly greater than it was for yellow plaques (34.9 +/- 16.3 vs. 8.7 +/- 2.7, p < 0.0001). Compensatory enlargement occurred more frequently with yellow plaques than with white plaques (56% vs. 9%, p < 0.01), while paradoxical shrinkage occurred more frequently with white plaques than it did with yellow plaques (64% vs. 4%, p < 0.001). CONCLUSIONS: Yellow plaques with an increased distensibility and a compensatory enlargement may be mechanically and structurally weak. As a result, mechanical "fatigue," caused by repetitive stretching, may lead to plaque disruption. Plaques with a high distensibility and a compensatory enlargement may be vulnerable.

Aged↗

PubMed2001

Characterization of a major form of human isatin reductase and the reduced metabolite.

Isatin, an endogenous indole, has been shown to inhibit monoamine oxidase, and exhibit various pharmacological actions. However, the metabolism of isatin in humans remains unknown. We have found high isatin reductase activity in the 105,000 g supernatants of human liver and kidney homogenates, and have purified and characterized a major form of the enzyme in the two tissues. The hepatic and renal enzymes showed the same properties, including an M(r) of 31 kDa, substrate specificity for carbonyl compounds and inhibitor sensitivity, which were also identical to those of recombinant human carbonyl reductase. The identity of the isatin reductase with carbonyl reductase was immunologically demonstrated with an antibody against the recombinant carbonyl reductase. About 90% of the soluble isatin reductase activity in the liver and kidney was immunoprecipitated by the antibody. The Km (10 microm) and k(cat)/K(m) (1.7 s(-1) x microm(-1)) values for isatin at pH 7.0 were comparable to those for phenanthrenequinone, the best xenobiotic substrate of carbonyl reductase. The reduced product of isatin was chemically identified with 3-hydroxy-2-oxoindole, which is also excreted in human urine. The inhibitory potency of the reduced product for monoamine oxidase A and B was significantly lower than that of isatin. The results indicate that the novel metabolic pathway of isatin in humans is mediated mainly by carbonyl reductase, which may play a critical role in controlling the biological activity of isatin.

Alcohol Oxidoreductases↗

PubMed2001

Adrenal cyst: a review of the Japanese literature and report of a case.

Adrenal cysts are a rare condition and are usually non-functioning and asymptomatic. A 44-year-old man was referred from another hospital because a left retroperitoneal tumor was incidentally found by abdominal echography. Laboratory findings including adrenal hormonal study were within the normal range. It showed homogeneously low intensity on T1-weighted images and high intensity on T2-weighted images on magnetic resonance imaging (MRI). Angiography demonstrated that the tumor was avascular and of left adrenal origin. The patient was diagnosed with left adrenal cyst and was intensively followed up with plans for examination with diagnostic imaging.

Adrenal Gland Diseases↗

PubMed2001

Localization of imidazolone in the peritoneum of capd patients: a factor for a loss of ultrafiltration.

The presence of dicarbonyl compounds, potent precursors of advanced glycation end products (AGEs), has been recognized in unused peritoneal dialysis (PD) fluids. Accumulation of AGEs has been implicated in the alteration of peritoneal membrane properties during continuous ambulatory peritoneal dialysis (CAPD) therapy. To determine whether imidazolone, an AGE specifically derived from 3-deoxyglucosone (3-DG), contributes to a decrease in ultrafiltration (UF) capacity of the peritoneal membrane in CAPD patients, we immunohistochemically evaluated the localization of imidazolone in peritoneal tissues from CAPD patients. Mesothelial thickening in the peritoneum was found in six of seven CAPD patients. Imidazolone distinctly accumulated in peritoneal tissues of CAPD patients, whereas it was hardly detected in those of patients with nonrenal disease. CAPD patients with a low UF capacity showed more extensive peritoneal deposition of imidazolone and more pronounced mesothelial thickening than those with a normal UF capacity. A CAPD patient with sclerosing peritonitis showed the most abundant localization of imidazolone among all CAPD patients. Gas chromatography/mass spectrometry showed that unused PD fluids contained high 3-DG concentrations (mean, 34.6 +/- 14.1 [SD] microgram/mL). In conclusion, the accumulation of imidazolone was noted in peritoneal tissues of CAPD patients, which preceded a decrease in UF capacity. Imidazolone modification may alter the quality of peritoneal membranes, presumably leading to a loss of UF and finally the development of sclerosing peritonitis.

Epithelium↗

PubMed2001

Mandibular range of motion after bilateral sagittal split ramus osteotomy with wire osteosynthesis or rigid fixation.

OBJECTIVES: An analysis was conducted to compare mandibular range of motion among Class II patients treated with wire osteosynthesis or rigid internal fixation after surgical mandibular advancement. STUDY DESIGN: Patients randomly received wire osteosynthesis and 8 weeks of maxillomandibular fixation (n = 49) or rigid internal fixation (n = 78). Mandibular range of motion was measured 2 weeks before surgery and 8 weeks, 6 months, and 1, 2, and 5 years after surgery. RESULTS: Both groups showed decreased mobility in all movement dimensions that progressively recovered to near presurgical levels over the 5-year follow-up period. The difference in range of motion between treatment groups was not statistically significant. Changes in proximal and distal segment position could not explain decreased mobility. CONCLUSIONS: Similar decreases in mandibular mobility occurred with wire and rigid fixation of a bilateral sagittal split ramus osteotomy after surgery. Long-term changes were statistically, but not clinically, significant.

Adult↗

PubMed2001

Administration of isoferulic acid improved the survival rate of lethal influenza virus pneumonia in mice.

BACKGROUND: Isoferulic acid (IFA) is a main active ingredient of the rhizoma of Cimicifuga beracleifolia, which is used frequently in Japanese traditional medicine as an anti-inflammatory drug. It has been revealed that IFA inhibits the production of macrophage inflammatory protein-2 (MIP-2), which is a murine counterpart of the chemokine family that may contribute to the pathogenesis of inflammatory diseases through the chemotactic activity for inflammatory and immune effector cells. AIM OF THE STUDY: In this study, we investigated the therapeutic effect of IFA on the progression of lethal influenza virus pneumonia in mice by comparison with that of dexamethasone (DX), a potent inhibitor for various inflammatory cytokines including MIP-2. METHODS: Mice were infected by intranasal inoculation of influenza virus under ether anesthesia. The IFA or DX was given by oral administration once daily for 4 days after infection. After infection, the survival rate and the change in body weight were daily monitored. RESULTS: IFA administration markedly improved the survival rate and body weight loss of influenza virus-infected mice in a suitable dose range (0.5 mg/day). However, DX administration did not show a beneficial effect at any dose. CONCLUSION: These data suggested that IFA is a novel tool not only for the intervention therapy, but also for the studies on the pathogenesis of influenza virus-induced pneumonia.

Animals↗

PubMed2001

Posttranscriptional regulation of cyclin A1 and cyclin A2 during mouse oocyte meiotic maturation and preimplantation development.

A shift from a meiotic cell cycle to a mitotic cell cycle occurs following fertilization. The molecular basis for this transition, however, is poorly understood. Although cyclin A1 is proposed to regulate M phase in the meiotic cell cycle, and cyclin A2 is proposed to regulate S and M phases in the mitotic cell cycle, little is known about changes in the expression levels of cyclin A1 and A2 during meiotic and mitotic cell cycles in mammalian oocytes. We report that the mRNA levels of both cyclins A1 and A2 decrease during oocyte maturation. The amount of cyclin A1 mRNA then increases between the one-cell and blastocyst stages, whereas that of cyclin A2 remains relatively constant. The amount of cyclin A1 protein declines during maturation and is not readily detected from the two-cell to the blastocyst stage. In contrast, cyclin A2 is not readily detected in the oocyte and metaphase II-arrested egg but is detected following fertilization and throughout the subsequent stages of preimplantation development. The appearance of cyclin A2 protein following fertilization positively correlates with an increase in the size of the mRNA. This increase, as well as the increase in the amount of cyclin A2 protein, is prevented by 3'-deoxyadenosine (3'-dA), an inhibitor of polyadenylation. Consistent with a role for cyclin A2 in regulating the G1/S transition, 3'-dA also inhibits DNA replication in treated one-cell embryos. These results suggest that regulation of expression of cyclins A1 and A2 is under posttranscriptional regulation and that the observed changes in their expression may be involved in the transformation of a meiotic cell cycle to a mitotic cell cycle following fertilization.

Animals↗

PubMed2001

Newly developed aminopropyl-silicate immunoisolation membrane for a microcapsule-shaped bioartificial pancreas.

An aminopropyl-silicate membrane, synthesized from tetramethoxysilane (TMOS) and 3-aminopropyltrimethoxysilane (APTrMOS) by the sol-gel method, was formed onto Ca-alginate gel beads via electrostatic interactions. The permeability of the membrane could be controlled easily by changing the molar ratio of both the precursors ([APTrMOS]/[TMOS]). The aminopropyl-silicate membrane prepared at a molar ratio of 2.40 rejected gamma-globulin and BSA successfully, whereas it permeated ovalbumin. This result indicates that the molecular weight cutoff point of this newly developed aminopropyl-silicate membrane is approximately 60 kDa.

Bioartificial Organs↗

PubMed2001

Enhanced production of macrophage inflammatory protein 2 (MIP-2) by in vitro and in vivo infections with encephalomyocarditis virus and modulation of myocarditis with an antibody against MIP-2.

Interleukin-8 (IL-8) is a chemotactic cytokine for neutrophils and lymphocytes. Macrophage inflammatory protein 2 (MIP-2) is a murine counterpart of IL-8. The present study was performed to determine whether MIP-2 aggravates murine myocarditis. We examined (i) the MIP-2-producing activity of encephalomyocarditis (EMC) virus-infected cultured macrophages, (ii) serial plasma MIP-2 levels in EMC virus-induced mice by enzyme-linked immunosorbent assay, and (iii) the effects of antimouse MIP-2 monoclonal antibody (MAb) in vivo upon myocarditis. The production of MIP-2 increased in an infection dose- and time-dependent manner in virus-infected RAW 264. 7 macrophages. Five-week-old C(3)H/He mice were inoculated with EMC virus. Plasma MIP-2 levels were significantly elevated in mice on days 7 and 14 postinfection. Mice were injected subcutaneously with anti-MIP-2 MAb at 10 microg/day (group 2) or 100 microg/day (group 3) on days 0 to 5 and were observed until day 21. Uninfected control mice (group 1) were prepared. The survival rate was higher in the anti-MIP-2-treated group (group 3), but not in group 2, than in the control group. Histopathological analysis revealed that cellular infiltration and myocardial necrosis with macrophage and T-cell accumulation were less prominent in the anti-MIP-2 MAb-treated group, but not in group 2, compared to the level in the controls. MIP-2 is an important naturally occurring inflammatory cytokine in myocarditis, and anti-MIP-2 MAb treatment may prevent the inflammatory response.

Animals↗

PubMed2001

Phenanthraquinone inhibits eNOS activity and suppresses vasorelaxation.

Diesel exhaust particles cause an impairment of endothelium-dependent vasorelaxation and are associated with cardiopulmonary-related diseases and mortality, but the mechanistic details are poorly understood. Since we reported previously that phenanthraquinone, an environmental chemical contained in diesel exhaust particles, suppresses neuronal nitric oxide synthase (nNOS) activity by shunting electrons away from the normal catalytic pathway, it was hypothesized that phenanthraquinone inhibits endothelial NOS (eNOS) activity and affects vascular tone. Therefore, the effects of phenanthraquinone on eNOS activity, endothelium-dependent relaxation, and blood pressure were examined in the present study. Phenanthraquinone inhibited NO formation evaluated by citrulline formed by total membrane fraction of bovine aortic endothelial cells with an IC(50) value of 0.6 microM. A kinetic study revealed that phenanthraquinone is a competitive inhibitor with respect to NADPH and a noncompetitive inhibitor with respect to L-arginine. Endothelium-dependent relaxation of rat aortic rings by ACh was significantly inhibited by phenanthraquinone (5 microM), whereas the endothelium-independent relaxation by nitroglycerin was not. Furthermore, an intraperitoneal injection of phenanthraquinone (0.36 mmol/kg) to rats resulted in an elevation of blood pressure (1.4-fold, P < 0.01); under this condition, plasma levels of stable NO metabolites, nitrite/nitrate, in phenanthraquinone-treated rats was reduced to 68% of control levels. The present findings suggest that phenanthraquinone has a potent inhibitory action on eNOS activity via a similar mechanism reported for nNOS, thereby causing the suppression of NO-mediated vasorelaxation and elevation of blood pressure.

Air Pollutants↗

PubMed2001

Physiological and pathological cardiac hypertrophy induce different molecular phenotypes in the rat.

Pressure overload, such as hypertension, to the heart causes pathological cardiac hypertrophy, whereas chronic exercise causes physiological cardiac hypertrophy, which is defined as athletic heart. There are differences in cardiac properties between these two types of hypertrophy. We investigated whether mRNA expression of various cardiovascular regulating factors differs in rat hearts that are physiologically and pathologically hypertrophied, because we hypothesized that these two types of cardiac hypertrophy induce different molecular phenotypes. We used the spontaneously hypertensive rat (SHR group; 19 wk old) as a model of pathological hypertrophy and swim-trained rats (trained group; 19 wk old, swim training for 15 wk) as a model of physiological hypertrophy. We also used sedentary Wistar-Kyoto rats as the control group (19 wk old). Left ventricular mass index for body weight was significantly higher in SHR and trained groups than in the control group. Expression of brain natriuretic peptide, angiotensin-converting enzyme, and endothelin-1 mRNA in the heart was significantly higher in the SHR group than in control and trained groups. Expression of adrenomedullin mRNA in the heart was significantly lower in the trained group than in control and SHR groups. Expression of beta(1)-adrenergic receptor mRNA in the heart was significantly higher in SHR and trained groups than in the control group. Expression of beta(1)-adrenergic receptor kinase mRNA, which inhibits beta(1)-adrenergic receptor activity, in the heart was markedly higher in the SHR group than in control and trained groups. We demonstrated for the first time that the manner of mRNA expression of various cardiovascular regulating factors in the heart differs between physiological and pathological cardiac hypertrophy.

Actins↗