Biomedical subjects

M Yamaoka

Publications and source records attributed to M Yamaoka.

At least 19 recordsLinked to original sources

PubMed2006

Genetic analysis of HLA, NA and HPA typing in type 2 diabetes and ASO.

We examined the genetic status of human leucocyte antigens (HLA), human platelet alloantigens (HPA) and neutrophil-specific antigens (NA) in patients with type 2 diabetes mellitus and diabetic arteriosclerosis obliterans (ASO). To our knowledge, the present study is the first report showing the relationship among three genetic factors in type 2 diabetes mellitus and ASO patients. HLA typing was performed by the polymerase chain reaction (PCR)-restriction fragment length polymorphism method. HPA-typing and NA-typing were by a PCR-sequence-specific primer method. The incidence of HLA-DRB1*1501 was found to be significant in type 2 diabetes and non-diabetic, particularly ASO-positive patients, compared to control subjects. There were no differences in NA1/NA2 between the control and diabetic or non-diabetic ASO groups. However, the frequency of NA2/NA2 in ASO-positive diabetes and non-diabetic ASO patients was significantly higher than controls. The a/b genotype of HPA-5a/5b was significantly lower in type 2 diabetes and non-diabetic ASO-positive patients than in controls. These findings suggest that genetic studies of HLA, NA and HPA could be useful to understand the pathogenesis of type 2 diabetes and ASO.

Adult↗

PubMed2005

Overeruption without root exposure of third molars and periodontal health in the mandible.

Bone formation is seen around the third molar even when the tooth is exposed to the oral environment due to overeruption. To determine if overeruption of the third molar with or without root exposure is related to the status of the exposure of other teeth in the mandible, using orthopantomographs, 424 third molars were studied in 371 patients who were over 41 years of age. The rate of overeruption and root exposure in third molars was measured, and its relationship to the number of teeth lost and the rate of root exposure in other teeth in the mandible was analyzed. Tooth loss in the group of third molars with overeruption without root exposure was greater than in that without overeruption or root exposure in men, whereas the relationship was not seen in women. We found that root exposures of other teeth in the group of third molars with overeruption without root exposure were significantly smaller than in those with root exposure in both genders. Third molars with overeruption without root exposure, in which bone formation was easy to observe for radiographic diagnosis, were correlated with periodontal health in the mandible, suggesting a component of precision determination for predicting resistance to periodontitis.

Adult↗

PubMed2004

Rapid estimation of lipids in oleaginous fungi and yeasts using Nile red fluorescence.

A rapid estimation method of the intracellular lipid content in microorganisms using a fluorescent probe, Nile red, was established by optimization of the Nile red staining and data processing. The protocol was designed to be applicable to a wide range of microorganisms and culture conditions. In the optimized procedure, cells diluted with buffer were stained with 0.24-0.47 microg/ml of Nile red for 5 min, and the fluorescent emission spectra in the wavelength region of 400 to 700 nm excited at 488 nm were acquired before and after the Nile red addition. The fluorescence intensity corresponding to the intracellular lipid amount was determined at the peak of the corrected spectrum. The value showed a linear relation with the lipid content of various oleaginous fungi and yeasts measured by the conventional method. The relative intensities against the unit lipid amounts were almost similar except for one yeast. For the application to mycelia forming various types of pellets, a simple and easy pretreatment of shaking with glass beads for 5-10 min was added to the protocol. The established method was applicable to estimate the lipid content of a wide range of microorganism cultures containing 2-5000 microg-lipid/ml-broth.

Biomass↗

PubMed2004

Induction of calcification in MC3T3-E1 cells by inorganic polyphosphate.

Relatively large amounts of inorganic polyphosphate [poly(P)] (400 microM) have been found in normal osteoblasts. The effect of poly(P) with an average chain length of 65 phosphate residues on cell calcification was therefore investigated with the use of MC3T3-E1 cells. Expression of both osteopontin and osteocalcin was induced by poly(P) (0.1 approximately 1 mM), and cells treated with poly(P) were strongly stained by alizarin red. In addition, the level of alkaline phosphatase activity induced in poly(P)-treated cells was two-fold higher than that in either orthophosphate-treated or control cells but not higher than that in cells treated with beta-glycerophosphate and ascorbic acid. In contrast, however, polyphosphatase activities were activated by poly(P) treatment to levels up to six-fold greater than that in controls. MC3T3-E1 cells may utilize poly(P) as a phosphate source for calcification rather than phosphate sources that are mainly produced by ALPase. Poly(P)-dependent induction of polyphosphatase activities may therefore promote calcification in MC3T3-E1 cells.

3T3 Cells↗

PubMed2003

Relationship of the hyoid bone and posterior surface of the tongue in prognathism and micrognathia.

In order to study relationship of the hyoid bone and posterior surface of the tongue in prognathism and micrognathia, we focused on the effect of the tongue on the upper airway lumen in 16 patients with Angle's Class II and 51 patients with Angle's Class III, and assessed the position of the hyoid, the depth from the posterior surface of the tongue, from the bottom of the vallecula and from hyoid bone to the posterior pharyngeal wall using lateral cephalograms. We were able to assess significant correlations between the posterior surface of the tongue and hyoid position in Angle's Class III. However, we found no association between them in Angle's Class II. This could be an adaptive feature of the genioglossus in response to hyoid localization to serve a compensatory role to prevent respiratory impairment in micrognathia at risk of apnoea.

Adolescent↗

PubMed2002

Production of long-chain polyunsaturated fatty acids by monoxenic growth of labyrinthulids on oil-dispersed agar medium.

A novel method is proposed for the production of long-chain polyunsaturated fatty acids (LCPUFA) by labyrinthulids. The method comprises a monoxenic culture with Psychlobacter phenylpyruvicus, using agar medium in which oil was dispersed. Soybean oil (SBO) was selected as the optimum material for an oil-dispersed agar medium. The labyrinthulids showed three-dimensional growth and an anastomosing ectoplasmic network in the SBO-dispersed agar medium. The oil plate changed from an opaque culture to a more transparent culture, due to growth of the labyrinthulids. The optimum culture conditions were 25-30 degrees C, an initial pH of 6-10 and artificial seawater with a salt concentration of 50-100%. These conditions are close to those where these strains were isolated. The maximum LCPUFA production (0.59 g/l) and dry cell weight (4.93 g/l) was obtained using strain S3-2 (isolated from Ishigaki Island) with 1.5% SBO at 14 days. This value was about 30 times more than that using glucose instead of SBO. The method proposed is promising in terms of the production of LCPUFA from reproducible oils.

Agar↗

PubMed2001

Multidrug resistance gene 1 expression in salivary gland adenocarcinomas and oral squamous-cell carcinomas.

In combined chemotherapy for head-and-neck cancer (HNC), salivary gland-cell adenocarcinoma (SGA) shows insufficient clinical outcome, and it has been suggested that the sensitivity and/or the mechanism of resistance to anti-cancer drugs are different between SGA and oral squamous-cell carcinoma (SCC). The aim of our study was to clarify whether P-glycoprotein (P-gp) expression is associated with multidrug resistance (MDR) in HNC and the difference in the process of its development between SGA and SCC. In immunohistochemical analysis, P-gp expression was found in the ductal cells of salivary glands but not in oral mucosal epithelium. In cancer tissues, a few SCC cells in 12 of 37 and most cells in all SGAs expressed P-gp. The intensive P-gp expression was significantly found in SGA compared with SCC. In an in vivo chemotherapeutic model using tumor-bearing nude mice, P-gp expression in counterparts was observed in only a few cells of the HSY line, while no P-gp expression was observed in Hepd cells. However, P-gp expression was developed in both HSY and Hepd cell lines after vincristine (VCR) treatment. RT-PCR showed that the mean ratios of mdr1 mRNA expression levels in HSY clones were 3.7-fold higher than those in Hepd clones after VCR treatment, while each cell line exhibited both induction and activated production of P-gp. These results suggest that P-gp-related MDR in SGA is an inherent phenotype caused by both high levels of P-gp induction and activated P-gp production during VCR treatment, while that in SCC is an acquired phenotype chiefly caused by induction of P-gp.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Mice with only rat mtDNA are required as models of mitochondrial diseases.

We examined the possibility of generation of mice expressing mitochondrial dysfunction by introduction of exogenous mtDNA from different species using mouse mtDNA-less (rho(0)) cells as mtDNA recipients. For determination of how genetically distant species of mtDNA could replicate in cells with only the mouse nuclear genome, we introduced mtDNA of the Syrian hamster (Mesocricetus auratus) into mouse rho(0) cells, and found that its replication was not sufficient to propagate to following generations, probably due to significant incompatibility between mouse-nuclear and Syrian hamster-mitochondrial genomes. On the other hand, rat mtDNA, which propagated stably and expressed mitochondrial dysfunction in mouse cells, also disappeared rapidly by exogenous introduction of mouse mtDNA, suggesting that mouse mtDNA in mouse cells must be excluded completely before introduction of rat mtDNA for generation of mice with rat mtDNA as mitochondrial disease models.

Animals↗

PubMed2001

A new isolation method for labyrinthulids using a bacterium, Psychrobacter phenylpyruvicus.

A new isolation method for labyrinthulids, marine microbes with spindle-shaped vegetative cells and gliding movement, is presented. The method for isolating labyrinthulids has been found to be more difficult and less reproducible than that for thraustochytrids, classified in the same order. So far serum seawater agar fortified with antibiotics has been proposed to be the best for isolation of labyrinthulids. The method presented here involves placing plant samples on an agar medium on which a marine bacterium, Psychrobacter phenylpyruvicus, has been grown. The new method, which utilizes fallen mangrove leaves as source material, was more than twice as effective as isolation agar medium without the bacterium. The increased effectiveness appears to derive partly from the bacterial colonies' delaying extension of fungal mycelium. The bacterium was more effective for the isolation of labyrinthulids than either the bacterium Shewanella sp. or the yeast Rhodotorula rubra.

Journal Article↗

PubMed2001

P-glycoprotein expression in human major and minor salivary glands.

Sodium pump and carbonic anhydrase activity have been described in the salivary glands. However, it remains to be elucidated whether these energy sources are used for secretion, excretion or both. In addition, the differences in the function of excretion and the role of the excretory duct cells are currently unknown in salivary glands. Expression of P-glycoprotein (P-gp), which is an ATPase-binding efflux pump, was tested in normal major and minor salivary glands from humans. P-gp was distributed on the basolateral membrane of serous acinar cells in the major salivary glands and the minor salivary glands. In particular, it was found to be present on the basolateral membrane and cytoplasm of acinar demilunar cells in the anterior lingual gland. Intense expression was identified in the basolateral membrane of the striated duct cells of the major salivary glands. P-gp was distinctly positive in the basolateral and/or luminal membranes of the initial part and in the luminal membrane of the terminal part of the excretory duct cells of the major salivary glands, whereas it was positive in the luminal membranes of both the initial part and the terminal part of the excretory duct cells of the minor salivary glands. These disparate distributions between the major and the minor salivary glands suggest different physiological excretions in the striated duct. P-gp may be physiologically involved in an important part of the transporter system, not only in the acinar serous cells and the striated duct cells, but also in the excretory duct cells in the salivary glands.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Relationship of third molar development and root angulation.

Angled roots are seen in mandibular third molars, which have a high frequency of incomplete impaction. We examined the relationship between incomplete impaction and angled roots. We enrolled orthopantomographs to determine the prevalence of angled roots in 239 men and 222 women aged 21--35 years with bilateral mandibular third molars. Angled roots were more frequent in subjects in whom the third molars had a different status on each side than in those with the same status on both sides (men: P<0.05; women: P<0.01). The incidence of women with angled roots in those with bilateral incomplete impactions was higher than that in those with bilateral eruption (P<0.01). Angled roots among mandibular third molars are related to environmental factors. Angled roots occur more frequently in women with incomplete impaction than in those with full eruption.

Adult↗

PubMed2001

Alteration of the angle of the coronoid process in prognathism.

Muscles and bones may dynamically affect the functions of each other, resulting in changes in the activity of the muscle and/or morphological change in the bones. However, alterations of the morphology of the coronoid process have not been documented in relation to the temporal muscle between the mandible and the cranium. Angles of the coronoid process to the line through the right and the left frontotemporale were measured on posteroanterior (PA) cephalograms in patients with normal occlusions and Class II, division 1 malocclusions, and those with true skeletal Class III malocclusions. Standard deviation of the angle of the coronoid process in patients with Class III malocclusions was greater than those subjects with normal occlusion or Class II, division 1 malocclusions. Differences of angles between the right and the left coronoid process in each patient of either sex were significantly large in true skeletal Class III malocclusions (both P < 0.001). Large variation of angle of the coronoid process was related to prognathism, and this effect may represent adaptation of temporal muscle function to a variety of alterations in mandibular morphology.

Adaptation, Physiological↗

PubMed2001

Three-dimensional STEM for observing nanostructures.

A new scanning transmission electron microscope has been developed for three-dimensional (3D) observations of nanostructures. Using double spherical fulcra, accurate eucentric rotation was achieved. Cylindrical specimens for 3D-observation were prepared by a microsampling technique using a focused ion beam. Copper via-holes of a semiconductor memory device and ZnO particles were observed by the 3D-STEM from different directions, and 3D-data of the ZnO particles were successfully reconstructed in a topography mode.

Journal Article↗

PubMed2001

Hypertension and impairment of endothelium-dependent relaxation of arteries from spontaneously hypertensive and L-NAME-treated Wistar rats.

Effects of chronic treatment of normotensive Wistar rats with N(omega)-nitro-L-arginine methyl ester (L-NAME) on blood pressure and on endothelium-dependent relaxation of the aorta, carotid and iliac arteries were studied. The endothelium-dependent relaxation was compared in arteries from normotensive Wistar Kyoto rats (WKY) and genetically hypertensive rats (stroke-prone spontaneously hypertensive rats, SHRSP). Chronic treatment of normotensive Wistar rats with L-NAME caused an elevation of blood pressure. The elevated blood pressure at 15 weeks of age was significantly higher in these animals than that of untreated Wistar rats, but lower than that of SHRSP. Endothelium-dependent relaxation of the arteries induced by acetylcholine (ACh) was almost abolished by chronic treatment with L-NAME. The remaining small relaxation in arteries from L-NAME-treated rats was completely inhibited by application of L-NAME (10(-4) M). In such preparations, higher concentrations of ACh induced a contraction, which was abolished by removal of the endothelium or by an application of indomethacin (10(-5) M). Endothelium-independent relaxation induced by sodium nitroprusside was similar between preparations from untreated and L-NAME-treated Wistar rats. Endothelium-dependent relaxation was significantly impaired in preparations from SHRSP, when compared with that in those from WKY. However, the impairment was less prominent in preparations from SHRSP than in those from L-NAME-treated rats. These results suggest that the impairment of endothelium-dependent relaxation in the arteries from L-NAME-treated rats is not due to the elevated blood pressure resulting from the chronic treatment, and that impairment of NO synthesis by the endothelium does not play a major role in the initiation of hypertension in SHRSP.

Animals↗

PubMed2001

T-cell responses to mitogens in atomic bomb survivors: a decreased capacity to produce interleukin 2 characterizes the T cells of heavily irradiated individuals.

Significant decreases in the fraction of lymphocytes that are CD4(+) and increases in serum levels of some classes of immunoglobulin have been reported to occur in atomic bomb (A-bomb) survivors and in victims of the Chernobyl nuclear plant accident. To investigate the long-term effects of nuclear radiation on cellular immunity in more detail, we used limiting dilution assays with peripheral blood mononuclear cell preparations to analyze the T-cell responses of 251 A-bomb survivors exposed to less than 0.005 Gy and 159 survivors exposed to more than 1.5 Gy. The percentages of CD2-positive cells that were capable of proliferating in response to phytohemagglutinin (PHA) in the presence of exogenous interleukin 2 (IL2) did not differ substantially between distally exposed and more heavily exposed survivors. The heavily exposed survivors appeared to possess fewer T cells that were capable of proliferating in response to concanavalin A (Con A) or of producing interleukin 2. Assuming that CD4 T cells were the ones primarily responsible for producing IL2 in response to Con A, we were able to estimate how many cells in any given CD4 T-cell population were actually producing IL2. The results indicated that peripheral blood samples from heavily exposed survivors contained significantly fewer IL2-producing CD4 T cells than did similar samples from distally exposed survivors, indicating that significant exposure to A-bomb radiation may have a long-lasting negative effect on the capacity of CD4 T-cell populations to produce IL2.

Adult↗

PubMed2000

Analysis of serum ErbB-2 protein and HLA-DRB1 in Japanese patients with lung cancer.

We investigated the relationship between ErbB-2 and HLA in order to clarify the clinical and genetic factors related to Japanese patients with lung cancer. Thirty-nine of the 73 lung cancer patients (53.4%) had elevated levels of ErbB-2. Only seven of 23 (30. 4%) patients with small cell carcinoma had elevated ErbB-2 levels. The prevalence of ErbB-2 positivity was highest (23 of 32; 71.8%) in patients with adenocarcinoma, while that in patients with squamous cell carcinoma was 50% (9 of 18). The frequencies of HLA A33, B44, B62, and B75 were lower in the lung cancer patients than in the control group. HLA-DR9 was higher in frequency in lung cancer patients than in the healthy controls (P<0.05), but HLA-DR6 was lower in frequency in lung cancer patients than in controls (P<0.01). DRB1*0901 was significantly higher in frequency in lung cancer patients than in controls (P<0.05). On the other hand, DRB1*0802, DRB1*1302 and the DRB1*14 group (*1401, *1403, *1405, *1406, and *1407) were completely absent in lung cancer patients. The frequencies of HLA B35, B52, B62, DRB1*0404, and DRB1*0406 were higher in the ErbB-2-positive lung cancer patients than in the ErbB-2-negative lung cancer patients. However, these types of HLA were not included in significant frequencies in our group of lung cancers. Our results suggest that some HLA-antigens/alleles participate in the pathogenesis of lung cancer in Japanese patients. In addition, the relationship between HLA-associated genetic factors and ErbB-2 seems to be weak. These findings suggest that ErbB-2 is correlated with prognostic factors for lung cancer independently of HLA-associated genetic factors.

Adenocarcinoma↗

PubMed2000

Japanese encephalitis DNA vaccine candidates expressing premembrane and envelope genes induce virus-specific memory B cells and long-lasting antibodies in swine.

Swine are an important amplifier of Japanese encephalitis (JE) virus in the paradomestic environment. In this study, two JE DNA vaccine candidates were evaluated for immunogenicity in swine. Both vaccine plasmids encode a cassette consisting of the signal of premembrane (prM), prM, and envelope (E) coding regions of JE virus. One plasmid, designated pcJEME, is based on a commercial vector (pcDNA3), whereas the other plasmid, designated pNJEME, is based on a vector (pNGVL4a) designed to address some of the safety concerns of DNA vaccine use. No differences were detected in the immunogenicity of these two plasmids in mice or swine. Swine immunized with the DNA vaccines at a dose of 100 to 450 microgram at an interval of 3 weeks developed neutralizing and hemagglutination-inhibitory (HAI) antibody titers of 1:40 to 1:160 at 1 week after the second immunization. However, swine administered two doses of a commercial JE vaccine (formalin-inactivated virus preparation; JEVAX-A) developed low (1:10) or undetectable antibody responses after their boost. Interestingly, serum antibody titers elicited by DNA vaccines in swine were higher than those detected in mice. Eight days after boosting with viral antigen (JEVAX-A) to detect an anamnestic response, swine immunized two times with the DNA vaccine showed a >100-fold elevation in HAI titer, indicating a strong recall of antibody response. Swine maintained detectable levels of HAI antibody for at least 245 days after two immunizations with a DNA vaccine. These results indicate that these DNA vaccines are able to induce virus-specific memory B cells and long-lasting antibodies in swine, which were of higher levels than those obtained with a commercial formalin-inactivated JE vaccine.

Animals↗

PubMed2000

A DNA vaccine expressing dengue type 2 virus premembrane and envelope genes induces neutralizing antibody and memory B cells in mice.

A dengue DNA vaccine candidate was developed and evaluated for immunogenicity in mice. The vaccine, designated pcD2ME, is a pcDNA3-based plasmid encoding the signal sequence of premembrane (prM), prM and envelope (E) genes of the New Guinea C strain of dengue type 2 virus. CHO-K1 cells transfected with pcD2ME expressed prM and E as determined by immunochemical staining with monoclonal antibodies. BALB/c mice inoculated intramuscularly with 100 microg of pcD2ME two or three times at an interval of 2 weeks developed a low level of neutralizing antibody (1:10 at a 90% plaque reduction). Immunization twice with 10 microg or 1 microg of pcD2ME or three times with 100 microg of pcDNA3 did not induce detectable levels of neutralizing antibody. Mice immunized two or three times with 100 microg of pcD2ME raised neutralizing antibody titers to 1:40 or greater on days 4 and 8 after challenge with 3x10(5) plaque forming units (PFU) of the New Guinea C strain of dengue type 2 virus, showing strong anamnestic responses to the challenge. In contrast, mice immunized two or three times with 100 microg of pcDNA3 developed no detectable neutralizing antibody on days 4 and 8 after challenge. These results indicate that immunization with pcD2ME induces neutralizing antibody and dengue type 2 virus-responsive memory B cells in mice.

Animals↗