Effect of calcium supplements on risk of myocardial infarction and cardiovascular events : meta-analysis

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Effect of Calcium Supplements on Risk of Myocardial Infarction and Cardiovascular Events: Meta-Analysis

Objective: To investigate whether calcium supplements increase the risk of cardiovascular events. Osteoporosis is a major cause of morbidity and mortality in older people. Calcium supplements margin- ally reduce the risk of fracture, and most guidelines recommend adequate calcium intake as an integral part of the prevention or treatment of osteoporosis. Consequently, calcium supplements are commonly used by people over the age of 50. Observational stu- dies suggest that high calcium intake might protect against vascular disease, and the findings are consis- tent with those of interventional studies of calcium sup- plements thatshow improvementin some vascular risk factors. In contrast, calcium supplements accelerate vascular calcification and increase mortality in patients with renal failure, in both dialysis and predialysis populations. Furthermore, a five year randomised controlled trial of calcium supplements in healthy older women, in which cardiovascular events were prespecified as secondary end points, recently reported possible increases in rates of myocardial infarction and cardiovascular events in women allocated to calcium. We carried out a meta-analysis of cardiovascular events in randomised trials of cal- cium supplements

Cigarette Smoking, Body Mass and Other Risk Factors for Fractures of the Hip in Women

Determinants of hip fractures were assessed using data from a network of hospital-based case-control studies from northern Italy. For the present analysis, cases were 209 women with fractures of the hip/proximal femur (aged 29 to 74, median age 62) admitted to a network of teaching and general hospitals in the greater Milan area; controls were 1449 women, aged 25 to 74 (median age 55), admitted for non-traumatic, acute conditions to the same network of hospitals. There was a strong direct association with smoking, the relative risk (RR) being significantly and similarly elevated both in ex-and in current smokers (RR 1.7 and 1.5 respectively) which rose to 2.4 for 25 or over cigarettes per day. The risk was associated with duration of smoking and apparently greater in post-menopausal women. Two factors showed significant inverse associations with hip fractures: relative weight, with relative risks of 0.5, 0.4 and 0.3 in subsequent categories of body mass index as compared with thinner ones, and the use of oestrogen replacement treatment (multi-variate RR = 0.4, 95% confidence interval (CI): 0.2-1.1). No association was observed with education or social class, selected indicator foods or alcohol consumption (RR for the highest consumption level = 1.0). The effects of smoking and body mass index appeared independent: compared with never smoking heavier women, the RR for smoking thin women was 4.6. Thus, this case-control study of hip fractures in a predominantly post-menopausal population of Italian women showed a strong association with smoking and appreciable protection from heavier body mass index and the use of oestrogen replacement treatmen

Lifestyle and Other Factors Explain One-Half of the Variability in the Serum 25-Hydroxyvitamin D Response to Cholecalciferol Supplementation in Healthy Adults

Background: Many factors have been associated with serum 25-hydroxyvitamin D [25(OH)D] concentrations in observational studies, with variable consistency. However, less information is available on factors affecting the magnitude of changes in serum 25(OH)D resulting from vitamin D supplementation. Objective: This study aimed to identify factors associated with the serum 25(OH)D response to supplementation with 1000 IU cholecalciferol/d during the first year of a large, multicenter, randomized, placebo-controlled colorectal adenoma chemoprevention trial. Methods: Eligible older adults who were not vitamin D–deficient [serum 25(OH)D12 ng/mL] were randomly assigned in a modified 2 3 2 factorial design to 1 of 4 groups: daily 1000 IU cholecalciferol, 1200 mg Ca as carbonate, both, or placebo. Women could elect 2-group (calcium 6 cholecalciferol) random assignment. In secondary analyses, we used multivariable models to assess factors associated with serum 25(OH)D concentrations in all enrollees (n = 2753) and with relative changes in serum 25(OH)D after 1 y cholecalciferol supplementation among those randomly assigned (n = 2187). Results: In multivariable models, 8 factors accounted for 50% of the variability of proportional change in serum 25(OH)D after cholecalciferol supplementation. Larger increases were associated with being female (34.5% compared with 20.5%; P \u3c 0.001) and with lower baseline serum 25(OH)D (P \u3c 0.0001), optimal adherence to study pill intake (P = 0.0002), wearing long pants and sleeves during sun exposure (P = 0.0002), moderate activity level (P = 0.01), use of extra vitamin D–containing supplements during the trial (P = 0.03), and seasons of blood draw (P # 0.002). Several genetic polymorphisms were associated with baseline serum 25(OH)D and/or serum response, but these did not substantially increase the models of R2 values. Other factors, including body mass index, were associated with serum 25(OH)D at baseline but not with its response to supplemental cholecalciferol. Conclusions: The factors that most affected changes in serum 25(OH)D concentrations in response to cholecalciferol supplementation included sex, baseline serum 25(OH)D, supplement intake adherence, skin-covering clothes, physical activity, and season. Genetic factors did not play a major role. This trial was registered at www.clinicaltrials.gov as NCT00153816

The Trial of Calcium and Vitamin D for the Prevention of Colorectal Adenomas

BACKGROUND Epidemiologic and preclinical data suggest that higher intake and serum levels of vitamin D and higher intake of calcium reduce the risk of colorectal neoplasia. To further study the chemopreventive potential of these nutrients, we conducted a randomized, double-blind, placebo-controlled trial of supplementation with vitamin D, calcium, or both for the prevention of colorectal adenomas. METHODS We recruited patients with recently diagnosed adenomas and no known colorectal polyps remaining after complete colonoscopy. We randomly assigned 2259 participants to receive daily vitamin D3 (1000 IU), calcium as carbonate (1200 mg), both, or neither in a partial 2Å~2 factorial design. Women could elect to receive calcium plus random assignment to vitamin D or placebo. Follow-up colonoscopy was anticipated to be performed 3 or 5 years after the baseline examinations, according to the endoscopist’s recommendation. The primary end point was adenomas diagnosed in the interval from randomization through the anticipated surveillance colonoscopy. RESULTS Participants who were randomly assigned to receive vitamin D had a mean net increase in serum 25-hydroxyvitamin D levels of 7.83 ng per milliliter, relative to participants given placebo. Overall, 43% of participants had one or more adenomas diagnosed during follow-up. The adjusted risk ratios for recurrent adenomas were 0.99 (95% confidence interval [CI], 0.89 to 1.09) with vitamin D versus no vitamin D, 0.95 (95% CI, 0.85 to 1.06) with calcium versus no calcium, and 0.93 (95% CI, 0.80 to 1.08) with both agents versus neither agent. The findings for advanced adenomas were similar. There were few serious adverse events. CONCLUSIONS Daily supplementation with vitamin D3 (1000 IU), calcium (1200 mg), or both after removal of colorectal adenomas did not significantly reduce the risk of recurrent colorectal adenomas over a period of 3 to 5 years. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00153816.

Fringe tracking and spatial filtering: phase jumps and dropouts

Fringe tracking in interferometers is typically analyzed with the implicit assumption that there is a single phase associated with each telescope in the array. If the telescopes have apertures significantly larger than r0 and only partial adaptive optics correction, then the phase measured by a fringe sensor may differ significantly from the "piston" component of the aperture phase. In some cases, speckle noise will cause "branch points" in the measured phase as a function of time, causing large and sudden jumps in the phase. We present simulations showing these effects in order to understand their implications for the design of fringe tracking algorithms.Comment: 9 pages, to be published in Proc. SPIE conference 7013 "Optical and Infrared Interferometry", Schoeller, Danchi, and Delplancke (eds.

Evaluation of the mechanical resistance of a powder-powder coating by modulated dry feed particle size analysis

Issu de : Conference on Particulate Systems Analysis, Stratford upon Avon, ENGLAND, SEP 21-23, 2005International audienceDry powder coating is a powerful method for modifying the surface properties of particles whilst retaining their essential bulk properties. The coating of a host powder by guest particles can be achieved via different means ranging from simple stirring together of the two components, to high energy impact coating in devices such as a Nara Hybridizer or Turbula Mixer. The quality of the powder coating resulting from such methods is an important parameter, which depends both on the force of the mechanical action used, and also the physicochemical interactions between the host and guest particles. Here, a method for evaluating the strength of host-guest interactions based on particle size analysis using a standard Malvern Mastersizer with dry powder feed is presented. Basically, the liberation of small guest particles from host particles can be achieved by increasing the air pressure, and the presence of liberated fine particles mixed with guest particles can be detected from differences in volume and number distributions. Complementary examination is undertaken using an environmental scanning electron microscope (ESEM). This technique has been used to evaluate the interaction strength of a coating of hydrophobic magnesium stearate on a herbal extract (Harpagophytum). It is shown that effective coating can be achieved by three different means: simple stirring, a Turbula Mixer and by using a Nara Hybridizer. The respective strength of the coatings is greater with increasing mechanical force used for the process. The method is proposed as a simple means of evaluating powder-powder coating processes

Adenoma Characteristics at First Colonoscopy as Predictors of Adenoma Recurrence and Characteristics at Follow-Up

All patients with colorectal adenomas may not require identical follow-up. We aimed to determine if adenoma characteristics at initial colonoscopy could predict adenoma recurrence or characteristics at follow-up. The number of adenomas and the size, type, and degree of atypia in 479 patients in a polyp prevention trial were evaluated as predictors of the same characteristics at follow-up using odds ratios (ORs) with 95% confidence intervals (CIs). Multiple logistic regression analysis was performed to determine if several baseline characteristics were simultaneously associated with outcome