Biomedical subjects

Y Tahara

Publications and source records attributed to Y Tahara.

At least 19 recordsLinked to original sources

PubMed2004

Over-expression system for secretory phospholipase D by Streptomyces lividans.

The structural gene for phospholipase D (PLD) of an actinomycete, Streptoverticillium cinnamoneum, together with its promoter region was introduced into Streptomyces lividans using a shuttle vector-pUC702-for Escherichia coli and S. lividans. The transformant was found to secrete a large amount of PLD (about 2.0x10(4) U/l, 42 mg/l) when cultured in a jar fermentor. Both an initial glucose concentration of 17.5 g/l and the feeding of carbon and nitrogen sources are effective for efficient secretion of PLD; under these culture conditions, the amount of PLD secreted reached a maximum level (about 5.5x10(4) U/l, 118 mg/l) after about 60 h. In contrast to the original producer, Stv. cinnamoneum, which secretes only a small amount of PLD (about 1.1x10(3) U/l, 2 mg/l) along with other extracellular proteins, this heterologous expression system is markedly more efficient in production of secretory PLD.

Actinobacteria↗

PubMed2004

Benchmark experiments for cyclotron-based neutron source for BNCT.

In the previous study, we found the feasibility of a cyclotron-based BNCT using the Ta(p,n) neutrons at 90 degrees bombarded by 50 MeV protons, and the iron, AlF(3), Al and (6)LiF moderators by simulations using the MCNPX code. In order to validate the simulations to realize the cyclotron-based BNCT, we measured the epithermal neutron energy spectrum passing through the moderators with our new spectrometer consisting of a (3)He gas counter covered with a silicon rubber loaded with (nat)B and polyethylene moderator and the depth distribution of the reaction rates of (197)Au(n,gamma)(198)Au in an acrylic phantom set behind the rear surface of the moderators. The measured results were compared with the calculations using the MCNPX code. We obtained the good agreement between the calculations and measurements within approximately 10% for the neutron energy spectra and within approximately 20% for the depth distribution of the reaction rates of (197)Au(n,gamma)(198)Au in the phantom. The comparison clarified a good accuracy of the calculation of the neutron energy spectrum passing through the moderator and the thermalization in a phantom. These experimental results will be a good benchmark data to evaluate the accuracy of the calculation code.

Boron Neutron Capture Therapy↗

PubMed2004

Chart analysis of body composition change among pre- and postadolescent Japanese subjects assessed by underwater weighing method.

OBJECTIVE: To examine the effect of age on the relationship between fat-free mass (FFM) and fat mass (FM), and fat-free mass index (FFMI) and fat mass index (FMI) by applying body composition chart analysis on pre- and postadolescent Japanese subjects. SUBJECTS AND METHOD: A sample of 516 children (244 boys and 272 girls) ranging in age from 11 to 17 y and 840 adults (288 male and 552 female subjects) ranging in age from 18 to 59 y were studied to determine a body composition by an underwater weighing method. FMI and FM were put on an x- and y-axis in body composition chart 1, and FFMI (FFM/ height(2)) and FMI (FM/height(2)) were taken on an x- and y-axis in body composition chart 2. RESULTS: In body composition chart 1, the plots for male subjects stayed flat from 11 to 14 y and after that a steady growth of FFM concurring with the FM growth was observed. During the adult stage, steady increments of FM and gradual decreases of FFM were observed. In body composition chart 2, steady increases of FFMI and gradual decreases of FMI were indicated in the male preadolescent period. In the adult stage, FFMI decreased year by year, although the FMI continued to increase. In female subjects, a conspicuous increase of FMI was observed throughout all periods of the present subjects. After middle age, the decline of FFMI was characteristically demonstrated in the chart. CONCLUSION: The relationships between FFM and FM are characteristically delineated on the body composition charts demonstrating clear gender differences. The change of body mass index was not reflecting the change of adiposity level in male subjects, although it was occurring along with the changes of the adiposity level in female subjects.

Adipose Tissue↗

PubMed2001

Transduction of antisense cyclin D1 using two-step gene transfer inhibits the growth of rat hepatoma cells.

Cyclin D1, one of the G(1) cyclins, is frequently overexpressed in several types of carcinomas and is thought to play an important role in tumorigenesis and tumor progression including hepatocellular carcinoma. We constructed a retrovirus vector-carrying rat cyclin D1 cDNA in the reverse orientation, resulting in expression of antisense (AS) cyclin D1 mRNA. For efficient transduction of this recombinant retrovirus, two-step gene transfer was performed. The rat hepatoma cell line (dRLh84) was infected with this recombinant retrovirus after preinfection with adenovirus expressing the retrovirus receptor. In the rat hepatoma cells, AS cyclin D1 mRNA was expressed, inducing a decrease in the expression of endogenous cyclin D1 mRNA and an inhibition of cell growth. Moreover, two-step gene transfer of AS cyclin D1 into s.c. hepatoma xenografts resulted in inhibition of tumor growth and prolonged animal survival. In the virus-infected tumor xenografts, expression of cyclin D1 was immunohistochemically inhibited, and apoptosis of hepatoma cells was detected. These findings suggest that transduction of AS cyclin D1 is useful as an adjunct to standard treatments for hepatocellular carcinoma.

Animals↗

PubMed2001

Effects of lifetime volleyball exercise on bone mineral densities in lumbar spine, calcaneus and tibia for pre-, peri- and postmenopausal women.

To clarify the effects of habitual volleyball exercise on bone in women during the menopausal periods, we measured bone mineral densities (BMDs) of the lumbar spine, calcaneus and tibia every 12 months for 2 years and estimated factors related to the baseline values and annual loss rates. Forty Japanese female volleyball players 42-62 years of age, who had belonged to the district non-professional club for more than 10 years on average, were recruited. Twenty women had regular menstruation at the start, but 7 underwent menopause during the study. Fifty-nine healthy women who did not participate in habitual exercise, but were otherwise comparable with the players, were recruited as the controls. The lumbar and calcaneus BMDs were measured by dual-energy X-ray absorptiometry (DXA), and both the volumetric BMDs and cross-sectional geometry at the diaphysis of the tibia were measured by peripheral quantitative computed tomography. The baseline BMDs of all measured sites and the values of the cortical area and moment of inertia of the tibia in the players were significantly higher than the values in the control women. In the peri- and postmenopausal players, the baseline values of the lumbar and calcaneus BMDs related to total years of participating in regular exercises during adulthood including volleyball (TYE), body mass index (BMI) and years since menopause (YSM). Tibia cortical area and moment of inertia values related to TYE. Annual bone loss rates in the tibia and calcaneus of players were significantly smaller than those values in the controls. However, the bone loss rates in the lumbar spine did not differ significantly between the groups. The bone loss rate in the calcaneus was significantly related to the current number of training hours per week and YSM. The rate of bone loss in the tibia was related to BMI. These data indicated that the total number of years participating in exercise activity during adulthood have positive effects on lumbar and calcaneus BMDs and the cortical structure of the tibia. Habitual volleyball exercise apparently did not alleviate the menopause-related bone loss in the lumbar spine.

Absorptiometry, Photon↗

PubMed2001

Apatite cement containing cis-diamminedichloroplatinum implanted in rabbit femur for sustained release of the anticancer drug and bone formation.

To treat malignant bone tumors, anticancer drugs are administered systemically, simultaneously with surgical therapy. However, drugs administered systemically have considerable invasive action on bone and other organs, and are also associated with various side effects. A bone-cementing material that can maintain high concentrations of anticancer drug at local sites and which can improve local structural weakness after tumor resection would constitute an ideal therapeutic means of treating malignant bone tumors. We therefore applied the concept of a drug delivery system and developed an implant containing calcium phosphate cement and the anticancer drug, cis-diamminedichloroplatinum (CDDP). The results of a sustained release test showed that the in-vitro cumulative release ratio of an implant containing 20% CDDP was over 60%, and a release rate of 0.1 mg/day was maintained. Experiments in vivo, using adult rabbits implanted with 10% CDDP, showed that the platinum (Pt) concentration in local bone marrow was an average 3200 microg/tissue.g 6 weeks after implantation. The concentration of Pt in the systemically administered group was 0.2 microg/tissue.g at 6 weeks. The Pt concentrations in other organs of the implanted group were: 3 microg/tissue.g or less in the kidney, and 2 microg/tissue.g or less in liver. These values were lower than those in the systemically administered group (3.5 and 2.1 microg/tissue.g, respectively). Local bone formation was observed by 12 weeks after implantation. Our implant maintained high Pt concentrations at local sites and the bone that formed reinforced the implant.

Animals↗

PubMed2001

Prevalence of age related maculopathy in a representative Japanese population: the Hisayama study.

AIM: To determine the prevalence of age related maculopathy (ARM) in a representative older Japanese population. METHODS: 1486 residents of Hisayama town, Fukuoka, Japan, aged 50 years or older were examined and the presence of ARM was determined by grading from fundus examination by indirect ophthalmoscope, slit lamp, and colour fundus photographs. RESULTS: The prevalence rate of drusen, which occurred with comparable frequency in men and women, was 9.6%. The frequency of drusen increased with age (p <0.01). Hyperpigmentation and/or hypopigmentation of the retina was present in 3.2%, geographic atrophy in 0.2%, and neovascular age related macular degeneration in 0.67%. The frequency of neovascular age related macular degeneration was significantly higher in the men (1.2% v. 0.34%, p <0.01). CONCLUSIONS: Early and late stage ARM is less common among Japanese people than among white people in Western countries, while late stage ARM is more common among Japanese than among black people.

Age Factors↗

PubMed2001

Cloning and high expression of catalase gene from bacillus sp. TE124.

An efficient expression system for producing catalase in Bacillus was developed. A catalase was purified from Bacillus sp. TE124 and the catalase gene was cloned by plaque hybridization with a probe constructed from the N-terminal amino acid sequence of the enzyme. The gene, containing an open reading frame of 1452 bp, was subcloned into pHY300PLK for self-cloning into the organism. As a result, the production of catalase increased 20-fold over that of the parent strain.

Journal Article↗

PubMed2001

Stiffness index of the calcaneus measured by quantitative ultrasound and menopause among Japanese women: The Hizen-Oshima Study.

Quantitative ultrasound (QUS) is a recently developed technique for evaluating fracture risk that can assess both bone mass and architecture. Although numerous studies have shown that menopause is associated with accelerated loss of bone mineral density, there are only a few studies on the association of QUS parameter (stiffness index) with menopausal status, especially among Japanese population. We examined age-specific changes in stiffness index, and relation with age, body mass index (BMI) and menopausal status among 506 community-dwelling Japanese women aged 40-89 years. Mean age at menopause (standard deviation) among 459 women with natural menopause was 49.4 (4.0) years. Stiffness index significantly decreased with increasing age. Stiffness index among 80-89 years age group was 40% lower, compared with that of 40-49 years age group. The greatest decline among adjacent ten-year age groups in stiffness index (15%) was found between 40-49 and 50-59 years of age. Multiple regression analysis showed that menopause related with decreased stiffness index, independent of age and BMI. Our findings indicate that menopause influences loss of bone mass and induces deterioration of bone trabecular microstructure.

Adult↗

PubMed2001

[Validity of various indices of obesity calculated from height and weight data for adult males use of the underwater-weighing method as a reference].

PURPOSE: We evaluated associations between excess body fat (%Fat) and various indices of obesity calculated from height and weight data. METHODS: In 147 adult males, %Fat was measured by the underwater-weighing method, and obesity indices were generated by the following 5 approaches: the Broca-Katsura (Katsura method), the Kato-Wataya (Kato method), Japan Society for the Study of Obesity (BMI method; based on the body weight at which the BMI is 22), and the Meiji Life Insurance Co. methods, and the Tables and Figures for Assessment of Obesity and Leanness published by the Ministry of Health and Welfare (MHW method). RESULTS: %Fat was 20% or more (obese) in 67 males (45.6%), 15-20% in 39 (26.5%), 10-15% in 35 (23.8%), and less than 10% in 6 (4.1%). The correlation coefficients between the obesity indices and %Fat were 0.612 for the Katsura method, 0.590 for the Kato-method, 0.611 for the BMI method, 0.612 for the Meiji Life Insurance Co. method, and 0.550 for the MHW method, being significant in each case (P < 0.01). When the cut-off point was set as 110% for each obesity index, sensitivity was highest with the Kato-method (82.1%), and specificity was highest with the Meiji Life Insurance Co. method (93.8%). With the MHW method, the receiver operating characteristic (ROC) curve was slightly farther from the point of sensitivity of 100% and 1-specificity of 0% than the others. CONCLUSION: Excess fat accumulation can not be accurately assessed by obesity indices calculated from body height and weight data. Validity was similar among obesity indices examined.

Adult↗

PubMed2000

Structural essentials of xenoestrogen dialkyl phthalates to bind to the estrogen receptors.

Xenoestrogen dialkyl phthalates, C(6)H(4)(COOC(n)H(m))(2), lack the phenolic hydroxyl group that is an essential structural component of the steroid A ring of 17 beta-estradiol. In order to examine whether dialkyl phthalates imitate the steroid structure, we have synthesized a series of 4-hydroxyl derivatives of dialkyl phthalates. The compounds were examined for their ability to displace [(3)H]17 beta-estradiol from the recombinant human estrogen receptor, which was expressed on Sf9 cells using the vaculovirus expression system. Dialkyl 4-hydroxyl phthalates were found to exhibit several-fold higher binding affinities compared to phthalates without the 4-hydroxyl group. From the analyses of receptor binding modes of dialkyl phthalates with and without the 4-hydroxyl group, it was deduced that the phthalic benzene ring mimics the steroid A ring. A biphasic binding curve observed for dicyclohexyl phthalate was also depicted by its 4-hydroxyl derivative, but it increased binding affinity only at the high affinity binding site. These data suggest that the phthalate benzene moiety recognizes the core of the estrogen receptor binding site and the hydrophobic interaction of the dialkyl moiety substantiates the binding characteristics of the phthalates. The present data indicate that even chemicals with slight structural analogy and weak receptor affinity can perturb the endocrine system when administered in high concentrations.

Binding Sites↗

PubMed2000

Multivariate analysis of factors influencing physical work capacity in wheelchair-dependent paraplegics with spinal cord injury.

The purpose of this study was to determine the main factors that influence physical work capacity (PWC) in wheelchair-dependent paraplegics with spinal cord injury (SCI) using multivariate analysis. Thirty-two male paraplegics with SCI (PSCI) performed a submaximal arm exercise test on an arm-cranking ergometer to determine their PWC (oxygen uptake: ml x kg(-1) x min(-1)) at a heart rate of 150 beats x min(-1) (PWC150). Hayashi's Quantification first type was applied to analyze the effects on PWC150 of six factors: age, smoking, level of physical activity, occupation, level of SCI and period since SCI. This analysis revealed high partial correlation coefficients between PWC150 and the level of SCI (0.651) and physical activity level (0.583) compared to other factors. In addition, the multiple correlation coefficient for six factors in predicting PWC150 was 0.726. These results indicate that the level of SCI and physical activity are the most important factors in determining PWC in wheelchair-dependent male PSCI.

Adult↗

PubMed2000

The relationship between spinal and appendicular bone mass modified by physical, historical, and lifestyle factors.

Spinal, radial, and calcaneal bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) and calcaneal bone mass measured by quantitative ultrasound densitometry (QUS) were compared in 83 healthy Japanese female volunteers. A significant and strong correlation was found within the same methods (r = 0.619 for lumbar spine and radius by DXA, r = 0.760 for lumbar spine and calcaneus by DXA, and r = 0.644 for calcaneus and radius by DXA), and within the same site (r = 0.758 for calcaneus by DXA and QUS). A lesser correlation was found when both the method and site were different (r = 0.521 for radius by DXA and calcaneus by QUS, and r = 0.583 for lumbar spine by DXA and calcaneus by QUS). Relations of spinal and appendicular bone mass were examined together with physical, historical, and lifestyle factors. Multiple correlation coefficients between bone mass at the lumbar spine and appendicular bone were 0.754 to 0.782, and all these increased after modification by physical, historical, and lifestyle factors in whichever appendicular bone. In the correlation between lumbar spine and radial BMD, past weight-bearing activity, age at menarche, family history of fractures, and body weight were chosen. Menstrual status, body weight, past weight-bearing activity, and present arm-using activity were chosen to determine the correlation between lumbar spine BMD and calcaneal bone mass by QUS. These results suggest that the incorporation of those factors improved the correlation between lumbar spine BMD and appendicular bone mass, especially in cases of lumbar spine BMD versus radial BMD or calcaneal bone mass by QUS.

Adult↗

PubMed2000

The 11 A resolution projection map of Na+/K+-ATPase calculated by application of single particle analysis to two-dimensional crystal images.

Two-dimensional (2D) crystals of Na+/K+-ATPase were vitrified and observed with an electron cryo-microscope that allowed specimen observation at liquid helium temperature. Images showing 19 A spots on the optical diffraction patterns were digitized and processed by a crystallographic method. After optimization of parameters for the image processing, the locally averaged images revealed that each 2D crystal contained heterogeneous molecules. Single particle analysis was therefore applied to the 2D crystal images to select homogeneous molecule images, and averaging the selected images significantly improved map quality. Five major peak densities were clearly resolved in the new projection map, while two were found previously.

Animals↗

PubMed2000

[Validity of various obesity indices calculated from height and weight in adult females using the underwater-weighing method as a reference].

We evaluated association between excess percent body fat (%Fat) and various obesity indices calculated from height and weight in 322 adult females. %Fat was measured by the underwater-weighing method, and obesity indices were based on the following 5 methods; Broca-Katsura method (Katsura method), Kato-Wataya method (Kato method), Japan Society for the Study of Obesity method (BMI method; based on the body weight at which BMI is 22), Meiji Life Insurance Co. method, and Table and Figure for the Assessment of Obesity and Leanness by the Ministry of Health and Welfare (MHW method). %Fat was 30% or more (obese) in 73 females (22.7%), 25-30% in 97 (30.1%), 20-25% in 88 (27.3%), and less than 20% in 64 (19.9%). The correlation coefficient between the obesity indices and %Fat were 0.71 for the Katsura method, 0.70 for the Kato-method, 0.72 for the BMI method, 0.70 for the Meiji Life Insurance Co. Method, and 0.63 for the MHW method, being significant for all methods (P < 0.01). When the cut-off point was set as 110% for each obesity index, sensitivity was the highest for the Katsura method (67.1%), and specificity was the highest for the Meiji Life Insurance Co. method (95.2%). Receiver operating characteristic (ROC) curves were similar in figure for the Katsura method, Kato-method, BMI method, and Meiji Life Insurance Co. method. For the MHW method, however, the curve was slightly farther from the point of sensitivity of 100% and 1-specificity of 0% than the others. Excess fat accumulation could not be accurately assessed by the obesity indices calculated from body height and weight. Validity was similar among the obesity indices except for the MHW method.

Adult↗

PubMed1999

The effect of tranilast on experimental proliferative vitreoretinopathy.

BACKGROUND: Tranilast has been clinically used for various allergic diseases. Recently, it has also been found to inhibit excessive scarring in wound healing processes. In this study, we examined the effects of tranilast on the treatment for experimental proliferative vitreoretinopathy (PVR). METHODS: Cultured rabbit conjunctival fibroblasts were injected intravitreously (50000 cells/eye) into the rabbit vitreous to induce experimental PVR. Immediately after that, tranilast (0.5-5 mg/ml, 0.1 ml/eye) was injected into the vitreous. Injection of vehicle solution was used as a negative control. PVR was clinically evaluated by masked observers using ophthalmoscopy and graded into six stages: 0 (no PVR) to 5 (severe PVR). The amount of transforming growth factor beta1 (TGF-beta1) in the vitreous was measured by ELISA method. Functional and morphological changes induced by 5 mg/ml tranilast were sought by electroretinography, light microscopy, and electron microscopy on day 28. RESULTS: The average stage of PVR in the eyes treated with tranilast (1 or 5 mg/ml) was significantly lower than that in the control group on days 14 and 28. There was no difference between the eyes treated with low-dose tranilast (0.5 mg/ml) and the control group. The amount of TGF-beta1 in the vitreous of tranilast-treated eyes was significantly lower than in the control group. The morphological and functional studies did not show any deleterious effect of tranilast on the retinal function and morphology. CONCLUSION: Tranilast effectively inhibits the progression of PVR without showing apparent toxicity of the eye. This agent has therapeutic value for PVR.

Animals↗

PubMed1999

The comparative benefits of glaucoma filtering surgery with an electric-pulse targeted drug delivery system demonstrated in an animal model.

PURPOSE: To evaluate the safety and effectiveness of glaucoma filtering surgery performed with the adjunctive use of bleomycin administered in conjunction with electric pulses (EP). DESIGN: Experimental study in rabbits. CONTROLS AND METHODS: Trabeculectomies were performed on pigmented rabbits (2 to 2.5 kg) using the following adjunctive treatments: 5 microM of topical bleomycin and EP (5V, 50 msec, 8 pulses) (group A: B+E+, n=15); bleomycin but no EP (group B: B+E-, n=15); 5 ,uM mitomycin C (MMC) and EP (group C: M+E+, n= 10); MMC but no EP (group D: M+E-, n=10); EP alone (group E: E+, n=10); and no adjunctive treatment (group F: E-, negative control, n=10). MAIN OUTCOME MEASURES: Intraocular pressure (IOP) was measured regularly for 60 days after the operation. Bleb formation and the condition of the conjunctiva, cornea, and retina were also regularly evaluated. Histologic studies were performed by light microscopy, and retinal functions were evaluated by electroretinography. RESULTS: Postoperative IOP was significantly lower than the preoperative level in all the animals until day 7. However, in groups E and F (the negative control) it returned to the preoperative level after day 7, and in groups B, C, and D after 15 days. The IOP of group A remained lower even on day 40. The average amount IOP was lowered or increased on day 20 was -6.4 mmHg (P < 0.05) in group A; -0.2 mmHg in group B; +1.2 mmHg in group C; and -3.25 mmHg in group D. The survival rate of the filtering blebs on day 20 was significantly higher in group A than in the other groups. Clinical and histologic studies uncovered no pathologic findings in any intra- or paraocular tissues. Electroretinographic evaluation of retinal function in group A showed no apparent change over the 60 days of the study. CONCLUSION: Glaucoma filtering surgery in rabbits with the adjunctive use of bleomycin in conjunction with EP significantly lowered IOP for up to 40 days without clinically, morphologically, or functionally harming intraocular tissues.

Animals↗

PubMed1999

Structural requirements of para-alkylphenols to bind to estrogen receptor.

Octyl- and nonylphenols in the environment have been proposed to function as estrogens. To gain insight into their structural essentials in binding to the estrogen receptor, a series of phenols with saturated alkyl groups at the para position, HO-C6H4-CnH2n+1 (n = 0-12), were examined for their ability to displace [3H]17beta-estradiol in the recombinant human estrogen receptor, which was expressed in Sf9 cells using the vaculovirus expression system. All tested para-alkylphenols were found to bind fully to the estrogen receptors in a dose-dependent manner. The interaction of alkylphenols with the receptor became stronger with increase in the number of the alkyl carbons and the activity was maximized with n = 9 of nonylphenol. Phenol (n = 0) exhibited weak but full binding to the receptor, whereas anisole with a protected phenolic hydroxyl group was completely inactive. Also, alkanes such as n-octane, 2,2, 4-trimethylpentane corresponding to tert-octane, and n-nonane exhibited no binding. The results indicate that the binding of para-alkylphenols to the estrogen receptor is due to the effect of covalent bonding of two constituents of the phenol and alkyl groups, which correspond to the A-ring and hydrophobic moiety of the steroid structure, respectively. When alkylphenols were examined for their receptor binding conformation by 1H-NMR measurements and ab initio molecular orbital calculations, it was suggested that nonbranched alkyl groups are in an extended conformation, while branched alkyl groups are in a folded conformation. These results suggest that branched and nonbranched alkyl moieties of alkylphenols interact differently with the lipophilic ligand binding cavity of the estrogen receptor when compared to the binding of 17beta-estradiol.

Chromatography, Gas↗