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41.
Gregory D Kirk Paul C Turner Yunyun Gong Olufunmilayo A Lesi Maimuna Mendy James J Goedert Andrew J Hall Hilton Whittle Pierre Hainaut Ruggero Montesano Christopher P Wild 《Cancer epidemiology, biomarkers & prevention》2005,14(2):373-379
High rates of hepatocellular carcinoma (HCC) in The Gambia, West Africa, are primarily due to a high prevalence of chronic hepatitis B virus infection and heavy aflatoxin exposure via groundnut consumption. We investigated genetic polymorphisms in carcinogen-metabolizing (GSTM1, GSTT1, HYL1*2) and DNA repair (XRCC1) enzymes in a hospital-based case-control study. Incident HCC cases (n = 216) were compared with frequency-matched controls (n = 408) with no clinically apparent liver disease. Although the prevalence of variant genotypes was generally low, in multivariable analysis (adjusting for demographic factors, hepatitis B virus, hepatitis C virus, and TP53 status), the GSTM1-null genotype [odds ratio (OR), 2.45; 95% confidence interval (95% CI), 1.21-4.95] and the heterozygote XRCC1-399 AG genotype (OR, 3.18; 95% CI, 1.35-7.51) were significantly associated with HCC. A weak association of the HYL1*2 polymorphism with HCC was observed but did not reach statistical significance. GSTT1 was not associated with HCC. The risk for HCC with null GSTM1 was most prominent among those with the highest groundnut consumption (OR, 4.67; 95% CI, 1.45-15.1) and was not evident among those with less than the mean groundnut intake (OR, 0.64; 95% CI, 0.20-2.02). Among participants who had all three suspected aflatoxin-related high-risk genotypes [GSTM1 null, HLY1*2 (HY/HH), and XRCC1 (AG/GG)], a significant 15-fold increased risk of HCC was observed albeit with imprecise estimates (OR, 14.7; 95% CI, 1.27-169). Our findings suggest that genetic modulation of carcinogen metabolism and DNA repair can alter susceptibility to HCC and that these effects may be modified by environmental factors. 相似文献
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Emily Banks Gillian Reeves Valerie Beral Diana Bull Barbara Crossley Moya Simmonds Elizabeth Hilton Stephen Bailey Nigel Barrett Peter Briers Ruth English Alan Jackson Elizabeth Kutt Janet Lavelle Linda Rockall Matthew G Wallis Mary Wilson Julietta Patnick 《British medical journal》2004,328(7451):1291-1292
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1,000 consecutive patients operated for retinal detachment were studied prospectively to determine the incidence of complications. Two parts of the operation were responsible for most of the vision-threatening complications: subretinal fluid drainage and the scleral buckle. In an attempt to reduce the complications of retinal detachment surgery, we have utilized a simplified procedure of transconjunctival cryotherapy and intravitreal gas injection with postoperative positioning. This study was limited to detachments with one or more breaks within one clock hour located within the superior eight clock hours of the fundus without signs of proliferative vitreoretinopathy. In a series of 20 consecutive patients, retinal reattachment was initially achieved in all cases. There were two recurrences that were reattached with scleral buckling. The final cure rate for the single pneumatic procedure, with six months follow-up, was 90%. No major complications were observed. This preliminary report suggests that pneumatic retinopexy has the advantages of reduced tissue trauma, no hospitalization, minimal complications, and reduced expense. The major disadvantage is the need for postoperative positioning for five days. 相似文献
46.
Arianne C Lim Kitty WM Bloemenkamp Kees Boer Johannes J Duvekot Jan Jaap HM Erwich Tom HM Hasaart Pieter Hummel Ben WJ Mol Jos PM Offermans Charlotte M van Oirschot Job G Santema Hubertina CJ Scheepers Willem A Schöls Frank PHA Vandenbussche Maurice GAJ Wouters Hein W Bruinse 《BMC pregnancy and childbirth》2007,7(1):1-6
Background
Adequate vitamin D concentrations during pregnancy are necessary to neonatal calcium homeostasis, bone maturation and mineralization. The aim of study is to evaluate serum vitamin D concentrations in mothers and their newborns and effect of vitamin D deficiency on pregnancy outcomes.Methods
552 pregnant women were recruited from Tehran University educating hospitals in the winter of 2002. Maternal and cord blood samples were taken at delivery. The serum was assayed for 25-hydroxyvitamin D3, calcium, phosphorus and parathyroid hormone.Results
The prevalence of vitamin D deficiency in maternal and cord blood samples were 66.8% and 93.3%, respectively (<35 nmol/l). There was significant correlation between maternal and cord blood serum concentrations of vitamin D. In mothers with vitamin D deficiency, cord blood vitamin D concentrations was lower than those from normal mothers (P = .001). Also, a significant direct correlation was seen between maternal vitamin D intake and weight gain during pregnancy.Conclusion
Consideration to adequate calcium and vitamin D intake during pregnancy is essential. Furthermore, we think it is necessary to reconsider the recommendation for vitamin D supplementation for women during pregnancy. 相似文献47.
Wever G. K. Althausen T. L. Biskind G. R. Kerr WM. J. 《The American journal of digestive diseases》1935,2(2):93-99
The American Journal of Digestive Diseases - In our patients with acute hepatitis, as a group, the Rose Bengal test was positive in 94 per cent, and the modified glucose tolerance test in 93 per... 相似文献
48.
Heidi N. Hilton N. Santucci A. Silvestri S. Kantimm L. I. Huschtscha J. D. Graham C. L. Clarke 《Breast cancer research and treatment》2014,143(3):423-433
The epithelium of the human breast is made up of a branching ductal–lobular system, which is lined by a single layer of luminal cells surrounded by a contractile basal cell layer. The co-ordinated development of stem/progenitor cells into these luminal and basal cells is fundamentally important for breast morphogenesis. The ovarian steroid hormones, progesterone (P) and 17β-estradiol, are critical in driving this normal breast development, yet ovarian activity has also been shown to be a major driver of breast cancer risk. We previously demonstrated that P treatment increases proliferation and augments the number of progenitor-like cells, and that the progesterone receptor (PR) is also expressed in the bipotent progenitor-enriched subfraction. Here we demonstrate that PR is expressed in a subset of CD10+ basal cells and that P stimulates this CD10+ cell compartment, which is enriched for bipotent progenitor activity. In addition, we have shown that P stimulates progenitor cells in human breast cancer cell lines and expands the cancer stem cell population via increasing the stem-like CD44+ population. As changes in cell type composition are one of the hallmark features of breast cancer progression, the demonstration that progenitor cells are stimulated by P in both normal breast and in breast cancer cells has critical implications in discerning the mechanisms of how P increases breast cancer risk. 相似文献
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Edward T. Tipper Emily I. Stevenson Victoria Alcock Alasdair C. G. Knight J. Jotautas Baronas Robert G. Hilton Mike J. Bickle Christina S. Larkin Linshu Feng Katy E. Relph Genevieve Hughes 《Proceedings of the National Academy of Sciences of the United States of America》2021,118(1)
Rivers carry the dissolved and solid products of silicate mineral weathering, a process that removes from the atmosphere and provides a key negative climate feedback over geological timescales. Here we show that, in some river systems, a reactive exchange pool on river suspended particulate matter, bonded weakly to mineral surfaces, increases the mobile cation flux by 50%. The chemistry of both river waters and the exchange pool demonstrates exchange equilibrium, confirmed by Sr isotopes. Global silicate weathering fluxes are calculated based on riverine dissolved sodium (Na+) from silicate minerals. The large exchange pool supplies Na+ of nonsilicate origin to the dissolved load, especially in catchments with widespread marine sediments, or where rocks have equilibrated with saline basement fluids. We quantify this by comparing the riverine sediment exchange pool and river water chemistry. In some basins, cation exchange could account for the majority of sodium in the river water, significantly reducing estimates of silicate weathering. At a global scale, we demonstrate that silicate weathering fluxes are overestimated by 12 to 28%. This overestimation is greatest in regions of high erosion and high sediment loads where the negative climate feedback has a maximum sensitivity to chemical weathering reactions. In the context of other recent findings that reduce the net consumption through chemical weathering, the magnitude of the continental silicate weathering fluxes and its implications for solid Earth degassing fluxes need to be further investigated.For decades, silicate weathering has been postulated to provide the negative climate feedback on Earth that prevents a runaway greenhouse climate like on Venus (1). Silicate mineral dissolution with carbonic acid converts atmospheric into carbonate, and releases essential nutrients to the terrestrial and marine biosphere (2). There have been many attempts to quantify the silicate weathering flux (3), mostly assuming that riverine dissolved sodium () is derived only from silicate minerals and rock salt. Here we show that there is a major addition of nonsilicate to the critical zone from ancient seawater, weakly bonded to sedimentary rocks and supplied to waters via the cation exchange process. The implication is not only that the silicate weathering flux is overestimated at a global scale, but that this nonsilicate is most important in regions previously thought to have the highest silicate weathering fluxes (so called weathering-limited regions) and greatest climate sensitivity.Cation exchange is a rapid chemical reaction between cations in the dissolved phase and mineral surfaces, particularly clays (4). Major and trace cations such as calcium (), magnesium (), sodium (), potassium (), and strontium () form the cation exchange pool, which balances negative charges on river-borne clay particle surfaces. This exchange takes place on interlayer sites, between the tetrahedral and octahedral layers, or on exposed surfaces (4). The importance of the cation exchange pool is well recognized in soils and aquifers (4, 5), has significant implications for enhanced weathering (6), and has been proposed as an important mechanism for buffering the composition of river waters (7–9). However, data on the riverine exchange pool are only available for two large river systems [Amazon and Ganges-Brahmaputra (10, 11)], despite its significance in providing a source of elements that are immediately bioavailable (12), and their potential for biasing the quantification of silicate weathering (9).It is increasingly recognized that rapidly reactive phases have a strong influence on the chemistry of river waters (13, 14). Cation exchange is a rapid reaction occurring continuously in soils, as riverine freshwaters evolve downstream interacting with particulate matter, and when they mix with seawater (15, 16). Important examples of cation exchange are the “swapping” of divalent cations and with , in particular when there is a major change in water composition such as when fluvial clays reach the ocean,[1]As a result, marine sediments have an exchange pool that is dominated by (17). Subsequently, these marine sediments are uplifted and emplaced on the continents where in the exchange pool is released by cation exchange with Ca-rich fresh waters (9). This has major implications for estimates of silicate weathering fluxes and associated consumption, because they are calculated using the content of rivers (3). Cerling et al. (9) proposed that the -rich exchange pool exerts an important control on natural waters, based on charge balance arguments from river water chemistry, but this hypothesis has never been rigorously tested (18) by determining the flux and composition of the exchange pool of rivers around the world.In this contribution, we present a large dataset of fluvial sediment cation exchange capacity (CEC) and composition in several of the world’s largest river basins. By comparing with the concomitant dissolved load chemistry, we demonstrate that 1) the exchange pool in river sediments is in equilibrium with the river water; 2) the fraction of mobile elements in the exchange pool relative to the dissolved pool can be significant, particularly in rapidly eroding, weathering-limited catchments; and 3) given reasonable inferences on the composition of old marine sedimentary rocks, modern-day silicate weathering has been overestimated and carbonate weathering has been underestimated. The results reduce the estimated magnitude of the silicate weathering flux, but increase the supply of base cations (e.g., , which can be a limiting nutrient) to the biosphere, suggesting a greater role of organic carbon burial compared with silicate weathering for the long-term atmospheric sink. 相似文献