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Intact Groups (intact + groups)
Selected AbstractsEndogenous estrogen status, but not genistein supplementation, modulates 7,12-dimethylbenz[a]anthracene-induced mutation in the liver cII gene of transgenic big blue rats,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 5 2005Tao Chen Abstract A growing number of studies suggest that isoflavones found in soybeans have estrogenic activity and may safely alleviate the symptoms of menopause. One of these isoflavones, genistein, is commonly used by postmenopausal women as an alternative to hormone replacement therapy. Although sex hormones have been implicated as an important risk factor for the development of hepatocellular carcinoma, there are limited data on the potential effects of the estrogens, including phytoestrogens, on chemical mutagenesis in liver. Because of the association between mutation induction and the carcinogenesis process, we investigated whether endogenous estrogen and supplemental genistein affect 7,12-dimethylbenz[a]anthracene (DMBA)-induced mutagenesis in rat liver. Intact and ovariectomized female Big Blue rats were treated with 80 mg DMBA/kg body weight. Some of the rats also received a supplement of 1,000 ppm genistein. Sixteen weeks after the carcinogen treatment, the rats were sacrificed, their livers were removed, and mutant frequencies (MFs) and types of mutations were determined in the liver cII gene. DMBA significantly increased the MFs in liver for both the intact and ovariectomized rats. While there was no significant difference in MF between the ovariectomized and intact control animals, the mutation induction by DMBA in the ovariectomized groups was significantly higher than that in the intact groups. Dietary genistein did not alter these responses. Molecular analysis of the mutants showed that DMBA induced chemical-specific types of mutations in the liver cII gene. These results suggest that endogenous ovarian hormones have an inhibitory effect on liver mutagenesis by DMBA, whereas dietary genistein does not modulate spontaneous or DMBA-induced mutagenesis in either intact or ovariectomized rats. Environ. Mol. Mutagen., 2005. Published 2005 Wiley-Liss, Inc. [source] The Effects of Native Language vs.FOREIGN LANGUAGE ANNALS, Issue 5 2001Target Language Captions on Foreign Language Students' DVD Video Comprehension A total of 169 intermediate (fourth-semester)students predicated as intact groups in the study. The passage material consisted of a 7-minute DVD episode about preparation for the Apollo 13 space-exploration mission. The students viewed only one of three passage treatment conditions: Spanish captions, English captions, or no captions. The English-language-dependent measures consisted of a written summary generated by the students and a 10-item multiple-choice test. The statistically significant results revealed that the English captions group performed at a substantially higher level than the Spanish captions group, which in turn performed at a considerably higher level than the no captions group on both dependent measures. The pedagogical value of using multilingual soundtracks and multilingual captions in various ways to enhance second language reading and listening comprehension is discussed. [source] Vitamin D and androgen regulation of prostatic growthJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2003Eddy S. Leman Abstract Vitamin D has been reported to inhibit the growth of prostate cancer cells and model systems. In this study, we examined the interaction between 1,25-dihydroxyvitamin D3 (1,25 D) in the presence or absence of endogenous testosterone on the growth and development of the adult rat prostate. Male Sprague,Dawley rats (165 days old) were either kept intact or castrated. Seven days after castration, the rats were treated with vehicle (control) or 1,25 D for 3 weeks and then sacrificed. Both ventral and dorsal lateral prostates were harvested; whole tissue lysates were collected and AR and VDR protein levels were analyzed by immunoblot analyses. Administration of 1,25 D in the intact animals decreased the prostatic size by 40%, compared to control animals, whereas 1,25 D did not influence the size of the prostate in castrated rats. 1,25 D administration in intact groups also increased both the AR and VDR protein levels by ,twofold, whereas in castrated groups, 1,25 D only increased the AR protein level by 1.5,2.5-fold. 1,25 D in the presence of endogenous testosterone inhibits prostatic growth, whereas 1,25 D in the absence of endogenous testosterone does not affect prostatic growth. The growth inhibitory activity of 1,25 D in the presence of testosterone may be mediated through the ligand activated AR and VDR pathways. These studies may reveal important information about the potential efficacy of 1,25 D as well as hormonal status in understanding the development of prostate diseases. J. Cell. Biochem. 90: 138,147, 2003. © 2003 Wiley-Liss, Inc. [source] An Empirical Investigation Demonstrating the Multidimensional DIF Paradigm: A Cognitive Explanation for DIFJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 2 2001Cindy M. Walker Differential Item Functioning (DIF) is traditionally used to identify different item performance patterns between intact groups, most commonly involving race or sex comparisons. This study advocates expanding the utility of DIF as a step in construct validation. Rather than grouping examinees based on cultural differences, the reference and focal groups are chosen from two extremes along a distinct cognitive dimension that is hypothesized to supplement the dominant latent trait being measured. Specifically, this study investigates DIF between proficient and non-proficient fourth- and seventh-grade writers on open-ended mathematics test items that require students to communicate about mathematics. It is suggested that the occurrence of DIF in this situation actually enhances, rather than detracts from, the construct validity of the test because, according to the National Council of Teachers of Mathematics (NCTM), mathematical communication is an important component of mathematical ability, the dominant construct being assessed. However, the presence of DIF influences the validity of inferences that can be made from test scores and suggests that two scores should be reported, one for general mathematical ability and one for mathematical communication. The fact that currently only one test score is reported, a simple composite of scores on multiple-choice and open-ended items, may lead to incorrect decisions being made about examinees. [source] | ||||||||||