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Biomedical subjects

K Yukawa

Publications and source records attributed to K Yukawa.

At least 19 recordsLinked to original sources
PubMed2006

Effective chemoradiotherapy protocol with 5-fluorouracil for cervical squamous cell carcinoma in vitro.

PURPOSE OF INVESTIGATION: 5-Fluorouracil (5FU) is frequently used in concurrent chemoradiotherapy for patients with advanced cervical cancer, although its optimal chemoradiotherapy protocol has not yet been established. In search of an optimal chemoradiotherapy protocol, some in vitro experiments were carried out. METHODS: The radiosensitive human cervical squamous cell carcinoma cell line ME180 was examined to investigate the effects of 5FU on radiosensitivity and the effects of irradiation on 5FU-sensitivity. RESULTS: 5FU dose-dependently enhanced cellular radiosensitivity at therapeutic concentrations. Although high doses of y-ray irradiation significantly reduced the 5FU-sensitivity, a low dose of irradiation at therapeutic doses (< 2.5 Gy) had no effect on 5FU-sensitivity of the irradiated cells. Cells pretreated with 5FU eight hours before irradiation showed significantly higher 5FU-sensitivity than cells concurrently treated with 5FU and irradiation. In contrast, cells treated with 5FU eight hours after irradiation showed significantly lower 5FU-sensitivity than cells concurrently treated with 5FU and irradiation. Moreover, all four post-irradiation surviving subclones obtained from repeatedly irradiated ME180 cells showed significantly lower 5FU-sensitivity than the non-irradiated parent cells. CONCLUSION: 5FU acts as a radiosensitizer for cervical squamous cell carcinoma and 5FU-sensitivity is reduced in irradiated cells. Therefore, 5FU administration immediately before irradiation may be a more effective treatment than concurrent chemoradiotherapy or post-irradiation chemotherapy with 5FU.

Antimetabolites, Antineoplastic↗
PubMed2005

Radiation enhances cisplatin-sensitivity in human cervical squamous cancer cells in vitro.

UNLABELLED: PURPOSE AND METHODS OF INVESTIGATION: Cisplatin (CDDP) is regularly used in concurrent chemoradiotherapy in patients with advanced cervical cancer although an effective protocol of chemoradiotherapy with CDDP has not yet been established. In search of a better chemoradiotherapy protocol, we investigated both CDDP effects on radiosensitivity and irradiation effects on CDDP-sensitivity using the radiosensitive human cervical squamous cell carcinoma cell line ME180. RESULTS: We found that CDDP did not affect cellular radiosensitivity, and that irradiation significantly enhanced CDDP-sensitivity. Moreover, all the four post-irradiation surviving subclones obtained from repetitively irradiated ME180 cells showed significantly higher CDDP sensitivities than those of the non-irradiated parent cells. CONCLUSION: These results suggest that an effective protocol would involve the concurrent administration of CDDP with radiotherapy and further administration following completion of radiotherapy in order to achieve higher CDDP-sensitivities.

Antineoplastic Agents↗
PubMed2000

The class IV semaphorin CD100 plays nonredundant roles in the immune system: defective B and T cell activation in CD100-deficient mice.

The class IV semaphorin CD100/Sema4D differentially utilizes two distinct receptors: plexin-B1 in nonlymphoid tissues, such as brain and kidney, and CD72 in lymphoid tissues. We have generated CD100-deficient mice and demonstrated that they have functional defects in their immune system, without apparent abnormalities in other tissues. The number of CD5(+) B-1 cells was considerably decreased in the mutant mice, whereas conventional B cells and T cells appeared to develop normally. In vitro proliferative responses and immunoglobulin production were reduced in CD100-deficient B cells. The humoral immune response against a T cell-dependent antigen and in vivo priming of T cells were also defective in the mutant mice. These results demonstrate nonredundant and essential roles of CD100-CD72 interactions in the immune system.

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

Regulation of transcription factor C/ATF by the cAMP signal activation in hippocampal neurons, and molecular interaction of C/ATF with signal integrator CBP/p300.

The CCAAT/enhancer binding proteins related activating transcription factor, C/ATF, is a mouse leucine-zipper transcription factor which is structurally homologous to ApCREB2, a suppressor integral to long-term synaptic plasticity in Aplysia. To gain a clue to whether C/ATF is involved in long-term plasticities of brain, we examined if the expression levels of C/ATF are modulated by cAMP, an inducer crucial for memory formation in Aplysia, Drosophila and mice. Our in situ hybridization analysis revealed the expression of C/ATF mRNA in hippocampal neurons. C/ATF protein levels increased after the cAMP signal stimulation in hippocampal neurons, while C/ATF mRNA levels remained constant. The human activating transcription factor 4 (hATF4), another homolog of ApCREB2, interacts with multiple domains of the coactivator CREB-binding protein (CBP), resulting in the potentiation of its ability to activate transcription. As expected, C/ATF was found to interact with three domains of CBP including CREB binding domain or kinase-inducible interaction (KIX) domain, the third cysteine-histidine-rich region (CH3 domain) and the nuclear receptor coactivator p160/SRC-1-interacting domain. Interestingly, C/ATF was further found to interact strongly with CREB binding protein/p300 (CBP/p300) CH1 domain. Mammalian two hybrid assays indicated that the interaction between C/ATF and CBP/p300 can occur in mammalian cells, and that the p300 CH1 domain is critical for the interaction. Thus, C/ATF may be implicated in transcription-dependent phase of hippocampal long-term plasticities through the modulation of its protein level under cAMP signal and the interaction with signal integrator, CBP/p300.

Activating Transcription Factor 4↗
PubMed1999

Clinical features of paroxysmal positional vertigo presenting combined lesions.

Benign paroxysmal positional vertigo (BPPV) is one of the common vestibular disorders. Canalolithiasis is thought to be a likely lesion. A canalith repositioning procedure (CRP by Epley) generally yields good resolution of vertigo and nystagmus. The authors confirmed the efficacy of this procedure on typical BPPV of the posterior semicircular canal type. We designed a new procedure for BPPV of the lateral canal type, which also yielded satisfactory results. BPPV sometimes presents a nystagmus pattern, which suggests multiple lesions. We have seen eight cases of BPPV showing nystagmus that combines both the posterior and the lateral canal types. Combined CRP was performed on these cases, which again gave good clinical results. Other BPPV cases were associated with central lesions. We must be aware that BPPV may involve multiple canals and may be associated with central lesions.

Aged↗
PubMed1998

Expressions of CCAAT/Enhancer-binding proteins beta and delta and their activities are intensified by cAMP signaling as well as Ca2+/calmodulin kinases activation in hippocampal neurons.

The transcription factor, Aplysia CCAAT enhancer-binding protein (ApC/EBP), plays a crucial role in long term facilitation, a synaptic mechanism of long term memory in Aplysia. To gain a clue to whether the mammalian C/EBP family of transcription factors are also involved in long term memory, we examined how C/EBP activities in hippocampal neurons can be modulated in response to cAMP and Ca2+, crucial inductive signals for memory formation. As a result, stimulation of either cAMP or Ca2+ signals in hippocampal neurons was found to enhance mRNA expressions and DNA binding activities of C/EBPbeta and C/EBPdelta. Furthermore, it is indicated that CaM kinases have essential roles for increasing the expression and DNA binding activities of C/EBPbeta in hippocampal neurons activated by membrane depolarization. Overexpression of constitutively active calcium/calmodulin-dependent kinase IV was found to directly stimulate either C/EBPbeta-dependent or C/EBPdelta-dependent transcription, reinforcing the evidence that C/EBP family members contribute to Ca2+-dependent transcription. Thus, these results suggest that C/EBPbeta and C/EBPdelta may be involved in the transcription-dependent phase of memory formation by increasing the expression of both the DNA binding and the transcriptional activities under the direction of cAMP and/or Ca2+ signaling in hippocampal neurons.

Animals↗
PubMed1998

Hypotensive effects of an angiotensin II type 1 receptor antagonist differ between exercised and sedentary rats aged from 4 to 19 weeks.

The hypotensive effects of an angiotensin II type 1 receptor antagonist TCV-116 were accelerated by swimming training in the early period of chronic administration in young rats. In the latter period, however, a severe decrease in blood pressure that appeared during long-term administration of TCV-116 was prevented by swimming training. Therefore exercise may contribute to the stabilization of blood pressure in young rats treated with TCV-116.

Angiotensin Receptor Antagonists↗
PubMed1996

Regulation of human papillomavirus transcription by the differentiation-dependent epithelial factor Epoc-1/skn-1a.

Human papillomavirus (HPV) early gene expression is closely linked to the differentiation status of infected epithelial cells. Typically, HPV type 16 (HPV16) or HPV18 E6 and E7 transcripts are only barely detectable within the undifferentiated basal cell layer, but their levels increase concomitantly with higher degrees of epithelial cell differentiation in suprabasal cells. A similar differentiation-dependent distribution of expression has been reported for the recently cloned epithelial cell specific transcription factor Epoc-1/skn-1a. We therefore examined whether Epoc-1/skn-1a may be directly involved in the activation of HPV E6/E7 transcription. Transient transfection studies showed that Epoc-1/skn-1a specifically stimulated the HPV16 and HPV18 E6/E7 promoters. Moreover, ectopically expressed Epoc-1/skn-1a was sufficient to stimulate HPV transcription also in nonepithelial cells. By deletion analyses, the Epoc-1/skn-1a-responsive element was mapped to the promoter-proximal portion of the HPV18 transcriptional control region. Footprint analyses and gel retardation assays demonstrated direct binding of Epoc-1/skn-1a to a hitherto uncharacterized site within this region. Mutation of the Epoc-1/skn-1a recognition site within the context of the complete HPV18 upstream regulatory region inhibited Epoc-1/skn-1a-mediated transactivation. These results show that Epoc-1/skn-1a can directly activate the E6/E7 promoter by binding to the viral transcriptional control region. Thus, Epoc-1/skn-1a may be involved in the differentiation-dependent regulation of HPV transcription.

Base Sequence↗
PubMed1995

Alterations of angiotensin II receptor contents in hypertrophied hearts.

Tsukuba hypertensive mice, which carry the human genes for renin and angiotensinogen, show cardiac hypertrophy as well as hypertension due to activation of the renin-angiotensin system (RAS). Here, we compared the cardiac angiotensin II (Ang II) receptor contents in these and normotensive control mice by means of ligand binding studies and competitive reverse transcription-polymerase chain reaction analyses. The content of the Ang II receptor type 1 (AT1) was significantly higher at both the protein (2.5-fold; p < 0.01) and mRNA (1.4-fold; p < 0.05) levels in the hypertensive mice than that in control mice. Almost identical levels of the Ang II receptor type 2 (AT2) expression were identified at the mRNA levels in the two types of mice, although the levels were less than 20% of those of AT1 mRNA in control mice. These results suggest that AT1 in the heart is upregulated in response to Ang II-induced hypertrophic change and that, in particular, the upregulation of AT1 in particular contributes to the development and/or maintenance of cardiac hypertrophy in conjunction with the increase in Ang II production, because AT1 is responsible for cardiac hypertrophy related to the RAS.

Animals↗
PubMed1995

Changes in body shape of young individuals from the aspect of adult physique model by factor analysis.

The purpose of this study was to clarify characteristics of age-related changes in body shape in adolescence, in 11- to 19-year-old boys and girls, by using previously reported physique models of adult men and women as the scale. The scale consisted of four factors obtained by factor analysis using 30 items as variables, such as the values measured for the physique, skinfold thickness and body composition. The four factors were Factor 1: body fat, Factor 2: mass, Factor 3: leg length to height ratio, and Factor 4: length, and were interpreted in the men and women in a similar manner. The subjects were 307 boys and 368 girls; all were healthy. Thirty items were measured and included the values measured for the physique, skinfold thickness and body composition, as in the men and women. Factor scores in the subjects were standardized by mean and standard deviation for each item in the adult subjects, and calculated for individuals by using the coefficient of factor score in the adult subjects. The body shapes of the boys and girls were investigated from the factor score by age calculated for each factor. The following results were obtained: 1. Factor 1 tended to gradually decrease and reached the adult level at 15 years of age in the boys.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Characteristics of body shape of female athletes based on factor analysis.

We examined the body shape of female athletes in comparison with female adult non-athletes by factor analysis. The subjects were 433 adult non-athletes and 464 athletes participating in 11 different sporting events. The physique, skinfold thickness and body composition of each subject were measured. The values obtained from non-athletes were analyzed by factor analysis, and the body shape of the athletes was then analyzed according to these factors. Four main factors with which 80 percent of total variance could be explained were body fat (Factor 1), mass (Factor 2), leg length to height ratio (Factor 3) and length (Factor 4), and were extracted from the values from non-athletes. The body shape of the athletes could be classified into 4 categories by cluster analysis for factor score of sporting events: less body fat and slim type, average type like non-athletes, muscular and well-balanced type, and tall and well-developed mass. Compared with non-athletes, female athletes for all sporting events had less body fat. Moreover, the athletes had a body shape suitable for their sporting events; i.e., their mass, length of leg and height.

Adult↗
PubMed1995

Japanese-language results for the speak strategy from Cochlear Pty Limited.

Recognition of speech sounds with a new speech-coding strategy, Speak, was compared with that of the Multipeak (Mpeak) strategy. Results of consonant, word, and sentence tests on 10 postlingually deaf subjects demonstrated that the performance of the Speak strategy significantly exceeded that of the Mpeak strategy under both quiet and noise conditions. Information transfer ratios for consonant features were improved by 20% to 40% with the Speak strategy under the noise condition. Thus, the Speak coding strategy can provide better speech sound perception than the Mpeak coding strategy.

Adult↗
PubMed1995

[Body density assessment utilizing skinfold thickness and age in Japanese women].

A study was conducted to investigate the validity of skinfold-based prediction equations for body density (g/ml) by Nagamine and Suzuki (1964), and to formulate more convenient and more useful equations for predicting body density from skinfold and age in women. Subjects of the study were 512 healthy women aged 18-66 years in or near Nagasaki City. The dependent variable in the multiple regression equation, body density, was determined by hydrostatic weighing. Independent variables included eight skinfolds, the sum of two skinfolds (triceps, subscapular), the sum of three skinfolds (triceps, subscapular, and abdominal), age, and body surface area. Skinfolds were measured with an Eiken-model skinfold caliper. Age (mean 30.1, range 18-66 yrs.), weight (mean 52.6, range 38.0-83.3 kg), height (mean 157.0, range 142.0-172.0 cm), and body density, (mean 1.04125, range 0.98806-1.08650 g/ml) were also recorded. Percent body fat was calculated using the formula by Brozek et al. and ranged from 6.4% to 48.3%. Multiple correlation coefficients (MR) and standard error (SE) of 10 regression equations (A-J) for predicting body density in women were compared. The best-fitting and the most convenient prediction equation for body density was equation-E. The regression equation developed for predicting body density was: body density = 1.07931-0.00059 x sum of three skinfolds(mm)-0.00015 x age (MR = 0.77 and SE = 0.0089). The equation was cross-validated on a different sample of 46 women. The correlation coefficient between predicted and hydrostatically determined body density was 0.813 (p < 0.001). Equation-E (Tahara's equation) appears to be useful in body density analysis particularly when the subjects are Japanese women, aged 18-50 yrs, with percent body fat 17 to 34%.

Adolescent↗
PubMed1995

[Body density assessment utilizing skinfold thickness and age in Japanese men].

A study was conducted to investigate the validity of skinfold-based prediction equations for body density (g/ml) by Nagamine and Suzuki (1964), and to formulate more convenient and more useful equations for predicting body density from skinfold and age in men. Subjects of the study were 257 healthy men aged 19-60 years in or near Nagasaki City. The regression equation for the dependent variable, body density, was determined by hydrostatic weighing. Independent variables included eight skinfolds, the sum of two skinfolds (triceps, subscapular), the sum of three skinfolds (triceps, subscapular, and abdominal), age, and body surface area. Skinfolds were measured with an Eiken-model skinfold caliper. Age (mean 33.1, range 19-60 yrs.), weight (mean 65.3, range 46.6-107.7 kg), height (mean 168.8, range 152.3-185.4 cm), and body density (mean 1.05874, range 1.00860-1.09020 g/ml) were also recorded. Percent body fat was calculated using the formula by Brozek et al. and ranged from 6.1% to 38.9%. Multiple correlation coefficients (MR) and standard error (SE) of 10 regression equations (A-J) for predicting body density in men were obtained. The best-fitting and the most convenient prediction equation for body density was equation-E.: body density = 1.09556-0.00062 x sum of three skinfolds (mm)-0.00028 x age (MR = 0.815 and SE = 0.0087 g/ml). The equation was cross-validated on a different sample of 45 men. The correlation coefficient between predicted and hydrostatically determined body density was 0.781 (p < 0.001). Equation-E (Tahara's equation) appears to be useful in body density analysis particularly when the subjects are Japanese men, aged 18-50 yrs, with percent body fat 10 to 30%.

Adult↗
PubMed1995

[Hydrostatic weighing, skinfold thickness, body mass index relationships in high school girls].

A study was conducted to evaluate body composition by hydrostatic weighing, skinfold thickness, and body mass index (BMI) in 102 senior high school girls, aged 15 to 18 in Nagasaki City. Body density measured by the underwater weighing method, was used to determine the fat weight (Fat) and lean body mass (LBM. or fat free weight: FFW) utilizing the formulas by Brozek et al. The results were as follows; 1. Mean values of body density were 1.04428 in the first grade girls, 1.04182 in the second grade, and 1.04185 in the third grade. 2. Mean values of percentage body fat (%Fat) were 23.5% in the first grade, 24.5% in the second and 24.5% in the third. 3. Percentage body fat (%Fat), lean body mass (LBM) and LBM/Height were not significantly with different advance of grade from the first to the third. 4. The correlation coefficients between percent body fat and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.78, 0.79, and 0.80 respectively and were all statistically significant (p < 0.001). 5. The correlation coefficients between BMI and the sum of two skinfold thicknesses, the sum of three skinfold thicknesses and the sum of seven skinfold thicknesses was 0.74, 0.74, and 0.74 respectively and were all statistically significant (p < 0.001). 6. Mean values of BMI, Rohrer index and waist-hip ratio (WHR) in all subjects (n = 102) were 20.3, 128.2 and 0.72 respectively.

Adolescent↗
PubMed1994

[Sex differences in interrelationships between percent body fat (%fat) and waist-to-hip ratio (WHR) in healthy male and female adults].

The purpose of the present study was to investigate sexual differences in relationships among percent body fat (%Fat), waist-to-hip ratio (WHR), waist-to-stature ratio (WSR), abdominal circumference to stature ratio (ASR), body mass index (BMI) and skinfold thicknesses in healthy male and female adults. Subjects were 64 males and 65 females, aged 22-60. Body density was measured by under water weighing and by skinfold anthropometry. Mean %Fat was 15.6% in males and 23.9% in females. Mean WHR was 0.83 in males and 0.72 in females. The correlation between %Fat and WHR was not significant in females (r = -0.104) but was significant in males (r = 0.631, p < 0.001). Highly significant correlations were obtained among %Fat, WSR, ASR, BMI, and sum of eight skinfolds in both sexes.

Adipose Tissue↗