Biomedical subjects

Akihiko Watanabe

Publications and source records attributed to Akihiko Watanabe.

At least 19 recordsLinked to original sources

PubMed2006

The outermost layer of egg-jelly is crucial to successful fertilization in the newt, Cynops pyrrhogaster.

The significance of egg-jelly layers in internal fertilization was evaluated in the newt, Cynops pyrrhogaster. In this species, six egg-jelly layers, J1, J2, J3, J4, J5 and the outermost J6 layers, are accumulated on the surface of the fertilizable eggs in pars convoluta of the oviduct. When a large number of sperm (about 6 x 10(5)) were placed on eggs having different numbers of jelly layers, all the eggs were fully fertilized, although many of the eggs developed abnormally. Upon insemination using about 600 sperm, only eggs with the full set of jelly layers were fertilized at a high rate with normal development. Since around 300 (the range of 48-1,192) sperm were observed on and in the egg-jelly in naturally spawned eggs, we conclude that the J6 layer must be present on the outermost surface of the egg-jelly for successful internal fertilization of the newt. Previous studies have suggested that the J6 layer is a prerequisite for the initiation of sperm motility and the acrosome reaction. In the present study, the fertilization rate decreased in eggs with a full set of jelly layers when inseminated using acrosome-reacted and motile sperm. However, the fertilization rate was high when motile sperm with intact acrosome was used. These results suggest that induction of the sperm acrosome reaction in the J6 layer is an important step in the internal fertilization of the newt.

Acrosome Reaction↗

PubMed2006

[Testotoxicosis].

Explore the source record for details and available documents.

Aromatase Inhibitors↗

PubMed2006

Study on temperature-dependent changes in hydrogen bonds in cellulose Ibeta by infrared spectroscopy with perturbation-correlation moving-window two-dimensional correlation spectroscopy.

Infrared (IR) spectra were measured for cellulose Ibeta prepared from the mantle of Halocynthia roretzi over a temperature range of 30-260 degrees C to explore the temperature-dependent changes in hydrogen bonds (H-bonds) in the crystal. Structural changes at the phase transition temperature of 220 degrees C are elucidated at the functional group level by perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy. The PCMW2D correlation spectra show that the intensities of bands arising from O3-H3...O5 and O2-H2...O6 intrachain H-bonds dramatically decrease at 220 degrees C, whereas the intensity changes of bands due to interchain H-bonds are not observed adequately. These results suggest that the phase transition is induced by the dissociation of the O3-H3...O5 and O2-H2...O6 intrachain H-bonds. However, the interchain H-bonds are not so much responsible for the transition directly.

Carbohydrate Conformation↗

PubMed2006

Temperature-dependent structural changes in hydrogen bonds in microcrystalline cellulose studied by infrared and near-infrared spectroscopy with perturbation-correlation moving-window two-dimensional correlation analysis.

Temperature-dependent structural changes in hydrogen bonds (H-bonds) in microcrystalline cellulose (MCC) were investigated by infrared (IR) and near-infrared (NIR) spectroscopy. The O-H stretching fundamentals and their first overtone bands were employed to explore the structural changes. In order to analyze the overlapping OH bands due to various H-bonds, perturbation-correlation moving-window two-dimensional (PCMW2D) correlation spectroscopy was applied to the IR and NIR data. Typical spectral variation temperatures were visualized by the PCMW2D correlation analysis. Structural changes in the strong H-bonds in MCC gradually occur in the temperature region of 25-130 degrees C, and they become greater above 130 degrees C. Both OH groups with H-bonds of intermediate strength and very weak H-bonds arise from the structural change of strong H-bonds in the temperature region of 40-90 degrees C, whereas the appearance of the latter OH groups with very weak H-bonds gradually becomes dominant above 90 degrees C. It is revealed from the present study that the glass transition at 184 degrees C induces the changes in the H-bonds in the Ibeta and the O3-H3...O5 intrachain H-bonds. Band assignments for the O-H stretching first overtone vibration region are proposed based on the results of the PCMW2D correlation analyses.

Algorithms↗

PubMed2006

A study on water adsorption onto microcrystalline cellulose by near-infrared spectroscopy with two-dimensional correlation spectroscopy and principal component analysis.

Water adsorption onto microcrystalline cellulose (MCC) in the moisture content (M(c)) range of 0.2-13.4 wt % was investigated by near-infrared (NIR) spectroscopy. In order to distinguish heavily overlapping O-H stretching bands in the NIR region due to MCC and water, principal component analysis (PCA) and generalized two-dimensional correlation spectroscopy (2DCOS) were applied to the obtained spectra. The NIR spectra in four adsorption stages separated by PCA were analyzed by 2DCOS. For the low M(c) range of 0.2-3.1 wt %, a decrease in the free or weakly hydrogen-bonded (H-bonded) MCC OH band, increases in the H-bonded MCC OH bands, and increases in the adsorbed water OH bands are observed. These results suggest that the inter- and intrachain H-bonds of MCC are formed by monomeric water molecule adsorption. In the M(c) range of 3.8-7.1 wt %, spectral changes in the NIR spectra reveal that the aggregation of water molecules starts at the surface of MCC. For the high M(c) range of 8.1-13.4 wt %, the NIR results suggest that the formation of bulk water occurs. It is revealed from the present study that approximately 3-7 wt % of adsorbed water is responsible for the stabilization of the H-bond network in MCC at the cellulose-water surface.

Adsorption↗

PubMed2006

[The efficacy of Gosyajinkigan for pollakisuria].

We investigated the efficacy of Gosyajinkigan in 20 patients with prostatic disease, in whom pollakisuria was not improved by treatment with drugs for lower urinary tract symptoms. Four and 8 weeks after treatment, the urinary frequency was significantly improved during both daytime and night. The efficacy rates for diurnal frequency and nocturia were 45% and 65%, respectively. The International Prostate Symptom Score (IPSS) was decreased 4 weeks after treatment, and the parameters of uroflowmetry, the residual urine volume and quality of life score were improved 8 weeks after therapy. It was concluded that Goshajinkigan was effective for pollakisuria with prostatic disease, and the administration of the agent for 8 weeks or longer was needed to improve lower urinary tract symptoms.

Aged↗

PubMed2005

Changes in the morphology of cell-size liposomes in the presence of cholesterol: formation of neuron-like tubes and liposome networks.

Spontaneous changes in the morphology of cell-size liposomes (dioleoylphosphatidylcholine, DOPC and egg PC) as model cells were investigated in the presence of cholesterol. Tube structures and liposome networks connected by the tubes were observed in the presence of 5-30% cholesterol by dark-field and laser-scanning microscopy. Furthermore, in the presence of more than 40 mol% of cholesterol, the tubes disappeared and changed to small liposomes. Thus, cholesterol induced a morphological change in giant liposomes from tubes to small liposomes. These phenomena may be related to the role of cholesterol in the morphological changes in living cells such as neurons.

Cell Membrane↗

PubMed2005

Metastatic colon cancer from intrahepatic cholangiocarcinoma.

A 62-year-old man had been followed because of an elevated serum level of carcinoembryonic antigen without the detection of any cancer lesions. However, there was a sudden increase in the serum level of carcinoembryonic antigen, and abdominal imagings showed a hepatic tumor with peripheral intrahepatic bile duct dilatation, and a submucosal tumor at the sigmoid colon with intact mucosa. Histopathological findings showed that the hepatic tumor had perineural invasion, suggesting an intrahepatic cholangiocarcinoma, and that the colon tumor infiltrated the submucosa, while its mucosa was intact. Both tumors showed similar pathological features and were positive for cytokeratin 20 and 7. These findings suggested intrahepatic cholangiocarcinoma with metastatic sigmoid colon cancer.

Bile Duct Neoplasms↗

PubMed2005

Ethical validity of palliative sedation therapy: a multicenter, prospective, observational study conducted on specialized palliative care units in Japan.

Although palliative sedation therapy is often required in terminally ill cancer patients to achieve acceptable symptom relief, empirical data supporting the ethical validity of this approach are lacking. The primary aim of this study was to systematically investigate whether empirical evidence supports the ethical validity of sedation. This was a multicenter, prospective, observational study, which was conducted by 21 specialized palliative care units in Japan. One-hundred two consecutive adult cancer patients who received continuous deep sedation were enrolled. Continuous deep sedation was defined as the continuous use of sedative medications to relieve intolerable and refractory distress by achieving almost or complete unconsciousness until death. Prior to the study, we conceptualized the ethical validity of sedation from the viewpoints of physicians' intent, proportionality, and autonomy. Sedation was performed mainly with midazolam and phenobarbital. The initial doses of midazolam and phenobarbital were 1.5 mg/hour and 20 mg/hour, respectively. Main administration routes were continuous subcutaneous infusion and continuous intravenous infusion, and no rapid intravenous injection was reported. Of 59 patients who received artificial hydration or could intake adequate fluids/foods orally before sedation, 63% received artificial hydration therapy after sedation, and in the remaining patients, artificial hydration was withheld or withdrawn due to fluid retention symptoms and/or patient wishes. Of 66 patients who were able to verbally express themselves, 95% explicitly stated that symptoms were intolerable. The etiologies of the symptoms requiring sedation were primarily related to the progression of the underlying malignancy, such as cancer cachexia and organ failure, and standard palliative treatments had failed: steroids in 68% of patients with fatigue, opioids in 95% of patients with dyspnea, antisecretion medications in 75% of patients with bronchial secretion, antipsychotic medications in 74% of patients with delirium, and opioids in all patients with pain. On the basis of the Palliative Prognostic Index, 94% of the patients were predicted to die within 3 weeks. Before sedation, 67% of the patients expressed explicit wishes for sedation. In the remaining 34 patients, previous wishes for sedation were noted in 4 patients, and in the other 30 patients, the families were involved in the decision-making process. The chief reason for patient non-involvement in the decision making was cognitive impairment. These data indicate that palliative sedation therapy performed in specialized palliative care units in Japan generally followed the principles of double effect, proportionality, and autonomy.

Adult↗

PubMed2005

Efficacy and safety of palliative sedation therapy: a multicenter, prospective, observational study conducted on specialized palliative care units in Japan.

Although palliative sedation therapy is often required in terminally ill cancer patients, its efficacy and safety are not sufficiently understood. The primary aims of this multicenter observational study were to 1) explore the efficacy and safety of palliative sedation therapy, and 2) identify the factors contributing to inadequate symptom relief and complications, using a prospective study design, clearly defined measurement methods, and a consecutive sample from 21 specialized palliative care units in Japan. A sample of 102 consecutive adult cancer patients who received continuous deep sedation were enrolled. Physicians prospectively evaluated the intensity of patient symptoms, communication capacity, respiratory rate, and complications related to sedation. Symptoms were measured on the Agitation Distress Scale, the Memorial Delirium Assessment Scale, and the ad hoc symptom severity scale (0 = no symptoms, 1 = mild and tolerable symptoms, 2 = intolerable symptoms for less than 15 minutes in the previous one hour, and 3 = intolerable symptoms continuing for more than 15 minutes in the previous one hour). Inadequate symptom relief was defined as presence of hyperactive delirium (item 9 of the Memorial Delirium Assessment Scale >or=2) or grade 2 or 3 symptom intensity 4 hours after sedation. The degree of communication capacity was measured on the Communication Capacity Scale. Palliative sedation therapy succeeded in symptom alleviation in 83% of the cases. Median time elapsed before patients initially had one continuous hour of deep sedation was 60 minutes, but 49% of the patients awakened once after falling into a deeply sedated state. The percentage of patients who were capable of explicit communication decreased from 40% before sedation to 7.1% 4 hours after sedation, and the mean Communication Capacity Score significantly decreased to the level of 15 points (P < 0.001). The respiratory rates did not significantly decrease after sedation (18 +/- 9.0 to 16 +/- 9.4/min, P = 0.62), but respiratory and/or circulatory suppression (respiratory rate <or= 8/min, systolic blood pressure <or= 60mHg, or 50% or more reduction) occurred in 20%, with fatal outcomes in 3.9%. There were no statistically significant differences in patient age, sex, performance status, target symptoms, or classes and initial dose of sedative medications between the patients with adequate and inadequate symptom relief. Respiratory and/or circulatory suppression was significantly more likely to occur in patients receiving sedation for delirium and those with higher levels on the Agitation Distress Scale. Higher dose of midazolam was significantly correlated with younger age, absence of icterus, pre-exposure to midazolam, and length of sedation. Palliative sedation therapy is effective and safe in the majority of terminally ill cancer patients with refractory symptoms. However, a small number of patients experience fatal complications related to sedation. Comparison studies of different sedation regimens are needed to determine the most effective and safe sedation protocol.

Adult↗

PubMed2005

Ordered progress of spermiogenesis to the fertilizable sperm of the medaka fish, Oryzias latipes, in cell culture.

Spermiogenesis is significant for producing sperm with equipment for achieving fertilization. Although multiple events occur in a particular order during spermiogenesis, it is unclear how the timing of those events is controlled. In the present study, we found that primary spermatocytes obtained from the spermatogenic testes of Oryzias latipes synchronously differentiated into sperm without contact with somatic cells in culture. Because those sperm can fertilize with mature eggs (Saiki et al., 1997), any events of spermiogenesis that are essential for achieving fertilization are completed in the in vitro spermiogenesis. In the in vitro spermiogenesis, the protamine gene expression was observed in the early period and mitochondrion localization was established in the same period. Those results suggest that both nuclear remodeling and organelle replacement begin in the early period of spermiogenesis. The cytoplasmic lobe was formed after the mitochondrion localization had been established. In most spermatids differentiated in cell culture, a flagellum began to elongate during the early period and continued to elongate up to 3 days. These results revealed the timings of the spermiogenetic events under the intrinsic control of the cultured spermatids toward the formation of fertilizable sperm in O. latipes.

Animals↗

PubMed2005

Poly(ethylene glycol) hydrogels cross-linked by hydrolyzable polyrotaxane containing hydroxyapatite particles as scaffolds for bone regeneration.

Poly(ethylene glycol) (PEG) hydrogels cross-linked by a hydrolyzable polyrotaxane containing hydroxyapatite particles (PRX-HAp) were developed as scaffolds for bone regeneration. Five scaffolds with various composition of the polyrotaxane, PEG and HAp particles were prepared to examine cell adhesion in vitro using rat primary cultured osteoblast. Cells were observed to attach well on a PRX-HAp that have the same weight ratio of the polyrotaxane and HAp particles at 7 days after seeding. These results indicate that HAp particles are necessary for cell adhesion and survival, but a higher ratio of the particles is not suitable for cell adhesion. The composites of rat osteoblast and the PRX-HAp were implanted subcutaneously in syngeneic rats and harvested at 5 weeks after implantation. In histological analysis, osteoblast-like cells became arrayed along the surface of the PRX-HAp, and osteoid-like tissues were observed in the region between a queue of osteoblast-like cells and PRX-HAp. These images are similar to intramembranous ossification, and it is expected that bone regeneration occurs on the surface of the PRX-HAp. This study strongly suggests the great potential of the PRX-HAp as scaffolds for bone regeneration.

Animals↗

PubMed2005

[Clinical study of ambulatory patient cancer chemotherapy for advanced colorectal cancer].

To evaluate ambulatory patient cancer chemotherapy, the clinical response, toxicities and survival time were analysed among 19 patients with non-curative or recurrent colorectal cancer who were treated by Uracil/Tegafur (UFT) plus oral Leucovorin (UZEL) for the past 2 years. The patients were administered UFT (300 mg/m2/day) and UZEL (75 mg/body/day) for 28 days with a one-week interval every 35 days as one course.A partial response (PR) was observed in 6 patients (31.6%) and stable disease (SD) in 8. The median survival time was 16 months. Although nausea/vomiting, diarrhea and leucopenia were noted, no severe side effects were observed. These results suggested that UFT plus Leucovorin therapy might be a useful cancer chemotherapy for ambulatory patients with advanced colorectal cancer.

Administration, Oral↗

PubMed2005

Antifungal effects of a tissue conditioner coating agent with TiO2 photocatalyst.

Tissue conditioners are susceptible to colonization by microorganisms. Therefore, the prevention of biofilm formation are important for oral hygiene. However, mechanical and chemical cleaning methods may cause clinical problems such as deformation or surface degradation of tissue conditioners. The objective of this study is to evaluate the antifungal effects of coating agents with a TiO2 photocatalyst. Photocatalytic antifungal effects on C. albicans biofilms and photodegradation effects of adsorbed protein were measured by colorimetric assays. Scanning electron microscopy was used to examine morphological changes in C. albicans. Viscosities of coating agents increased with incorporation of TiO2. However, both of coating agents with TiO2 were acceptable to the application by brush. The antifungal and protein degradation effects increased with the concentration of TiO2 in the coating agents. These effects also increased with radiation time. After 90 min radiation, the viability of C. albicans was reduced to 16.2+/-3.3 %. Scanning electron microscopy observation showed C. albicans remained on the coated surfaces even after 90 min radiation. These results suggest that coating agents with TiO2 photocatalyst can be effective for the maintenance of tissue conditioners when dentures are removed; during sleep.

Adsorption↗

PubMed2004

Synthesis and structure-activity relationships of novel IKK-beta inhibitors. Part 3: Orally active anti-inflammatory agents.

A series of 2-amino-3-cyano-4-alkyl-6-(2-hydroxyphenyl)pyridine derivatives was synthesized and evaluated as I kappaB kinase beta (IKK-beta) inhibitors. Modification of a novel IKK-beta inhibitor 1 (IKK-beta IC(50)=1500 nM, Cell IC(50)=8000 nM) at the 4-phenyl ring and 6-phenol group on the pyridine core ring resulted in a marked increased in biological activities. An optimized compound, 2-amino-6-[2-(cyclopropylmethoxy)-6-hydroxyphenyl]-4-piperidin-4-yl nicotinonitrile, exhibited excellent in vitro profiles (IKK-beta IC(50)=8.5 nM, Cell IC(50)=60 nM) and a strong oral efficacy in in vivo anti-inflammatory assays (significant effects at 1mg/kg, po in arachidonic acid-induced ear edema model in mice).

Animals↗

PubMed2004

AFM observation of collapse and expansion of phosphoric acid-demineralized dentin.

The objective of this study is to provide additional data regarding morphological changes that occur to dentin matrices following demineralization with etchants. Our understanding of the mechanism of diffusion of comonomers into the demineralized substrate is very limited. It has been hypothesized that certain water-soluble polyelectrolytes (acidic proteins) and neutral proteins in dentin can influence the collapse of demineralized dentin when it is air dried. Some of these solubilized substances are thought to aggregate by the action of Ca cations, which become dissolved during H(3)PO(4) etching, ultimately resulting in some degree of collapse. In the current study, dentin surfaces were examined by atomic force microscopy (AFM) before and after treatment by 10% H(3)PO(4)containing increasing concentrations of CaHPO(4). Reversal of matrix collapse by aqueous 30% 2-hydroxyethyl methacrylate (HEMA) was evaluated by AMF for 60 min. The results demonstrate two forms of matrix collapse; we speculate that one form is induced by acidic noncollagenous polyelectrolytes and the other by neutral peptides. Our data indicate that further evaluation of the influence of endogenous noncollagenous proteins must be studied to understand the mechanism of the collapse and reexpansion dynamics of demineralized dentin networks.

Animals↗

PubMed2004

Nano-scale surface modification of a segmented polyurethane with a phospholipid polymer.

Nano-scale modification of a segmented polyurethane (SPU) with cross-linked 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer was performed to obtain a biocompatible elastomer. To control the domain size and the depth of the modified layer, various compositions of monomers, including MPC, 2-ethylhexyl methacrylate (EHMA), and glycerol 1,3-diglycerolate diacrylate, were examined. SPU film was immersed in the monomer solution and visible light irradiation was applied to initiate polymerization to the SPU film that was held by mica to condense MPC units at the surface. The surfaces of the obtained film were analyzed by X-ray photoelectron spectroscopy and water contact angle measurement. The surface density of MPC units changed with the monomer concentration, and the density was the highest when the ratio between MPC and EHMA was 7:3. In modified SPU films, 6- to 25-nm MPC unit-enriched domains were observed and the density of these domains gradually decreased with depth. The sizes of the domains depended on the MPC composition in the monomer solution. The mechanical properties of the modified films as evaluated by tensile strength measurement under wet conditions were not significantly different from those of SPU. With increase in the existence of MPC unit-enriched domains on the MEG film surface, platelet adhesion and activation were remarkably reduced compared to the SPU film. This nano-scale surface modification may be a useful technique for applying elastic polymer biomaterials.

Biocompatible Materials↗

PubMed2004

Effect of remaining demineralised dentine on dental microleakage accessed by a dye penetration: how to inhibit microleakage?

OBJECTIVES: To demonstrate that microleakage has taken place at the defect, which was analysed previously by a tensile test using dumbbell shaped specimens trimmed from bonded resin/dentine restorations, and to suggest how microleakage can be inhibited reliably in dental treatment. METHODS: A total of 60 Class V box cavities were prepared at the cemento-enamel junction on fresh bovine incisors and randomly divided into four groups of 15 specimens each. Exposure times of etching for 10:3 conditioner were set at 10, 30 or 60 s, and for 10% phosphoric acid (positive control) at 10 s. The cavity walls were rinsed with water for 10 s, air-dried for 10 s and hybridised with 4-META/MMA-TBB resin. All the cavities were filled with a light cured resin composite and stored in 37 degrees C water for 24 h and then immersed in 15% methylene blue for 2 h. The length of dye penetration along the interface was graded by defined criteria and analysed using Kruskal-Wallis and Mann-Whitney tests. The dye penetration patterns were examined by light microscopy and the remaining demineralised dentine was analysed by Transmission Electron Microscopy (TEM). RESULTS: The least leakage score was obtained in 10s-10:3 etched group with 12 out of 15 specimens demonstrating no leakage. Leakage was significantly lower at the cementum margin than for the other three groups. No significant difference in the extent of greatest dye penetration was found between the 60s-10:3 and 10s-phosphoric etched groups. Dye penetration along the cementum margins was significantly higher than that of the enamel margins in all groups, except the 10s-10:3 etched group. TEM examination confirmed that there were exposed collagen fibrils in the remaining demineralised dentine, where microleakage had taken place. SIGNIFICANCE: It could be concluded from this study that microleakage has taken place at the defect in the bonded specimens which has correlations with zones of incompletely infiltrated demineralised dentine that was observed using TEM. A reliable method of inhibiting microleakage is the presence of well prepared hybridised dentine.

Acid Etching, Dental↗