1,769 research outputs found
Plugged hollow shaft makes fatigue-resistant shear pin
Shear pin coupling with plugged hollow shaft provides required load capacity for shaft protection and has no groove to induce fatigue failure
Some ultrastructural and physiological studies of Phycomyces Sporangiophores
Although the Phycomyces sporangiophore has been the object of numerous physiological investigations little is known of its ultrastructure or of the changes that occur within it during growth and development. This is partly due to the failure of some workers to obtain satisfactory fixation of the sporangiophore for ultrastructural investigations. Investigations were made for suitable fixation procedures which might help to elucidate the fine structure of the sporangiophore during growth and development. Using the fixation procedures developed, long microfilaments lying almost parallel to the long axis of the sporangiophore and closely associated with mitochondria were revealed. These microfilaments probably determine the path along which the mitochondria move and may account for the multistriate streaming of organelles as seen in the phase contrast microscope. Investigations for a discrete gravity receptor proved negative but did reveal an upward displacement of the large central vacuole concurrent with the development of a geotropic curvature. I was not able to find any organelle which might function as a photoreceptor. The ultrastructural changes occurring during the development of the sporangium and germination of the spores are described
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Haplotype analysis of common variants in the BRCA1 gene and risk of sporadic breast cancer
INTRODUCTION: Truncation mutations in the BRCA1 gene cause a substantial increase in risk of breast cancer. However, these mutations are rare in the general population and account for little of the overall incidence of sporadic breast cancer. METHOD: We used whole-gene resequencing data to select haplotype tagging single nucleotide polymorphisms, and examined the association between common haplotypes of BRCA1 and breast cancer in a nested case-control study in the Nurses' Health Study (1323 cases and 1910 controls). RESULTS: One haplotype was associated with a slight increase in risk (odds ratio 1.18, 95% confidence interval 1.02–1.37). A significant interaction (P = 0.05) was seen between this haplotype, positive family history of breast cancer, and breast cancer risk. Although not statistically significant, similar interactions were observed with age at diagnosis and with menopausal status at diagnosis; risk tended to be higher among younger, pre-menopausal women. CONCLUSIONS: We have described a haplotype in the BRCA1 gene that was associated with an approximately 20% increase in risk of sporadic breast cancer in the general population. However, the functional variant(s) responsible for the association are unclear
A polymorphism in the 3' untranslated region of the gene encoding prostaglandin endoperoxide synthase 2 is not associated with an increase in breast cancer risk: a nested case-control study
INTRODUCTION: Prostaglandins are integral components in the cellular response to inflammation, promoting cellular proliferation and angiogenesis. The enzyme responsible for the conversion of arachidonic acid to prostaglandins in response to inflammation is prostaglandin endoperoxide synthase 2/cyclo-oxygenase 2 (PTGS2/COX2). Polymorphisms in the PTGS2 gene have been associated with various diseases, including inflammatory bowel disease and cancer of the lung, colorectum, and breast. METHODS: We genotyped the five most common polymorphisms (rs20417, rs5277, rs20432, rs5275, and rs4648298) in the Nurses' Health Study (1,270 cases, 1,762 controls) to test the hypothesis that polymorphisms in PTGS2 are associated with breast cancer risk, using logistic regression analyses. The Nurses' Health Study 2 (317 cases, 634 controls) and Harvard Women's Health Study (702 cases, 703 controls) were used to further examine putative associations. RESULTS: The rs5275 polymorphism in the 3' untranslated region of the PTGS2 gene was associated with a decrease in breast cancer risk. We therefore genotyped this single-nucleotide polymorphism in the Nurses' Health Study 2 and Harvard Women's Health Study. Similar results were observed in these subsequent analyses, with no statistically significant heterogeneity in risk estimates between studies. In pooled analyses, women homozygous for the T allele at rs5275 had a 20% lower risk of breast cancer than those homozygous for the C allele (odds ratio 0.80, 95% confidence interval 0.66 to 0.97). CONCLUSION: Although this polymorphism may be associated with a decrease in breast cancer risk among Caucasian women, we provide strong evidence that it is not associated with an increased risk of breast cancer
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Flavonoid Intake and Plasma Sex Steroid Hormones, Prolactin, and Sex Hormone-Binding Globulin in Premenopausal Women
Background: Flavonoids potentially exert anti-cancer effects, as suggested by their chemical structures and supported by animal studies. In observational studies, however, the association between flavonoids and breast cancer, and potential underlying mechanisms, remain unclear. Objective: To examine the relationship between flavonoid intake and sex hormone levels using timed blood samples in follicular and luteal phases in the Nurses’ Health Study II among premenopausal women. Methods: Plasma concentrations of estrogens, androgens, progesterone, dehydroepiandrosterone (DHEA), DHEA sulfate (DHEAS), prolactin, and sex hormone-binding globulin (SHBG) were measured in samples collected between 1996 and 1999. Average flavonoid were calculated from semiquantitative food frequency questionnaires collected in 1995 and 1999. We used generalized linear models to calculate geometric mean hormone concentrations across categories of the intake of flavonoids and the subclasses. Results: Total flavonoid intake generally was not associated with the hormones of interest. The only significant association was with DHEAS (p-trend = 0.02), which was 11.1% (95% confidence interval (CI): −18.6%, −3.0%) lower comparing the highest vs. lowest quartile of flavonoid intake. In subclass analyses, the highest (vs. lowest) quartile of flavan-3-ol intake was associated with significantly lower DHEAS concentrations (−11.3% with 95% CI: −18.3%, −3.7%, p-trend = 0.01), and anthocyanin intake was associated with a significant inverse trend for DHEA (−18.0% with 95% CI: −27.9%, −6.7%, p-trend = 0.003). Conclusion: Flavonoid intake in this population had limited impact on most plasma sex hormones in premenopausal women. Anthocyanins and flavan-3-ols were associated with lower levels of DHEA and DHEAS
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Association between Cutaneous Nevi and Breast Cancer in the Nurses' Health Study: A Prospective Cohort Study
Background: Cutaneous nevi are suggested to be hormone-related. We hypothesized that the number of cutaneous nevi might be a phenotypic marker of plasma hormone levels and predict subsequent breast cancer risk. Methods and Findings: We followed 74,523 female nurses for 24 y (1986–2010) in the Nurses' Health Study and estimate the relative risk of breast cancer according to the number of cutaneous nevi. We adjusted for the known breast cancer risk factors in the models. During follow-up, a total of 5,483 invasive breast cancer cases were diagnosed. Compared to women with no nevi, women with more cutaneous nevi had higher risks of breast cancer (multivariable-adjusted hazard ratio, 1.04, 95% confidence interval [CI], 0.98–1.10 for 1–5 nevi; 1.15, 95% CI, 1.00–1.31 for 6–14 nevi, and 1.35, 95% CI, 1.04–1.74 for 15 or more nevi; p for continuous trend = 0.003). Over 24 y of follow-up, the absolute risk of developing breast cancer increased from 8.48% for women without cutaneous nevi to 8.82% (95% CI, 8.31%–9.33%) for women with 1–5 nevi, 9.75% (95% CI, 8.48%–11.11%) for women with 6–14 nevi, and 11.4% (95% CI, 8.82%–14.76%) for women with 15 or more nevi. The number of cutaneous nevi was associated with increased risk of breast cancer only among estrogen receptor (ER)–positive tumors (multivariable-adjusted hazard ratio per five nevi, 1.09, 95% CI, 1.02–1.16 for ER+/progesterone receptor [PR]–positive tumors; 1.08, 95% CI, 0.94–1.24 for ER+/PR− tumors; and 0.99, 95% CI, 0.86–1.15 for ER−/PR− tumors). Additionally, we tested plasma hormone levels according to the number of cutaneous nevi among a subgroup of postmenopausal women without postmenopausal hormone use (n = 611). Postmenopausal women with six or more nevi had a 45.5% higher level of free estradiol and a 47.4% higher level of free testosterone compared to those with no nevi (p for trend = 0.001 for both). Among a subgroup of 362 breast cancer cases and 611 matched controls with plasma hormone measurements, the multivariable-adjusted odds ratio for every five nevi attenuated from 1.25 (95% CI, 0.89–1.74) to 1.16 (95% CI, 0.83–1.64) after adjusting for plasma hormone levels. Key limitations in this study are that cutaneous nevi were self-counted in our cohort and that the study was conducted in white individuals, and thus the findings do not necessarily apply to other populations. Conclusions: Our results suggest that the number of cutaneous nevi may reflect plasma hormone levels and predict breast cancer risk independently of previously known factors. Please see later in the article for the Editors' Summar
External perceptions of successful university brands
Branding in universities has become an increasingly topical issue, with some institutions committing substantial financial resources to branding activities. The particular characteristics of the sector present challenges for those seeking to build brands and it therefore seems to be timely and appropriate to investigate the common approaches of those institutions perceived as having successful brands.
This study is exploratory in nature, seeking to investigate how successfully UK universities brand themselves, whether they are distinct and if the sector overall communicates effectively. This is approached through examining the perspective of opinion formers external to universities but closely involved with the sector – a key stakeholder group in UK higher education
Overall, the research’s exploratory nature aims to further the debate on effective branding in UK higher education.
The findings and conclusions identify some issues surrounding university branding activity; most UK universities were considered to be distinct from one another, but few were seen to have real fully formed brands. Although a number of institutions that were seen as having more ‘successful’ brands were identified, it was argued that whilst many UK universities communicate their brand well enough to key stakeholders, they fail to consistently do this across all audiences. It was also suggested that UK universities may concentrate on areas of perceived immediate strategic importance (in terms of branding) to an extent where others are neglected
The Mitochondrial A10398G Polymorphism, Interaction with Alcohol Consumption, and Breast Cancer Risk
Polymorphisms in the mitochondrial genome are hypothesized to be associated with risk of various diseases, including cancer. However, there has been conflicting evidence for associations between a common polymorphism in the mitochondrial genome (A10398G, G10398A in some prior reports) and breast cancer risk. Reactive oxygen species, a by-product of mitochondrial energy production, can lead to oxidative stress and DNA damage in both the mitochondria and their cells. Alcohol consumption, which may also lead to oxidative stress, is associated with breast cancer risk. Therefore, we hypothesized that polymorphisms in the mitochondrial genome interact with alcohol consumption to alter breast cancer risk. We genotyped the A10398G polymorphism in a case-control study nested within the Nurses' Health Study (NHS, 1,561 cases, 2,209 controls). We observed an interaction between alcohol consumption (yes/no) and A10398G on breast cancer risk (p-int = 0.03). The risk associated with alcohol consumption was limited to carriers of the 10398G allele (Odds Ratio 1.52, 95% Confidence Interval 1.10–2.08 comparing drinkers to non-drinkers). However, we were unable to replicate these findings in the Women's Health Study (WHS, 678 cases, 669 controls), although the power to detect this interaction in the WHS was low (power = 0.57). Further examination of this interaction, such as sufficiently powered epidemiological studies of cancer risk or associations with biomarkers of oxidative stress, may provide further evidence for GxE interactions between the A10398G mitochondrial polymorphism and alcohol consumption on breast cancer risk
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