Search

The risk of death in hemodialysis patients treated with calcium-containing phosphate binders or sevelamer is not known. We assessed all-cause mortality in 127 patients new to hemodialysis assigned to calcium-containing binders or sevelamer after a median follow-up of 44 months from randomization. This was a predetermined secondary end point of a randomized clinical trial designed to assess progression of coronary artery calcium (CAC) scores in the two treatment arms. Thirty-four deaths occurred during the follow-up period: 23 in subjects randomized to calcium-containing phosphate binders and 11 in subjects randomized to sevelamer. Baseline CAC score was a significant predictor of mortality after adjustment for age, race, gender, and diabetes with increased mortality proportional to baseline score (P=0.002). Mortality was borderline significantly lower in subjects randomized to sevelamer (5.3/100 patient years, confidence interval (CI) (2.2–8.5) compared to those randomized to calcium-containing binders (10.6/100 patient years, CI 6.3–14.9) (P=0.05). The greater risk of death for patients treated with calcium-containing phosphate binders persisted after full multivariable adjustment (P=0.016, hazard ratio 3.1, CI 1.23–7.61). In subjects new to hemodialysis baseline CAC score was a significant predictor of all-cause mortality. Treatment with sevelamer was associated with a significant survival benefit as compared to the use of calcium-containing phosphate binders.Kidney International (2007) 71, 438–441. doi:10.1038/sj.ki.5002059; published online 3 January 2007 [ABSTRACT FROM AUTHOR]

BACKGROUND: Recent data suggest that acute hyperglycemia may increase in vivo free radical production. This increased production has been implicated in many disease processes. OBJECTIVE: The objective was to investigate whether a diet with a high glycemic index (GI) or glycemic load (GL) is associated with greater oxidative stress as measured by 2 lipid peroxidation markers, malondialdehyde (MDA) and F(2)-isoprostanes (IsoPs). DESIGN: Plasma MDA and IsoP concentrations were measured in 292 healthy adults, and dietary GI and GL were assessed by using a validated food-frequency questionnaire. Cross-sectional associations between GI, GL, and the 2 markers were examined by using multiple regression techniques with adjustment for potential confounding variables. RESULTS: Dietary GI was positively associated with both plasma MDA and IsoPs. The mean multivariate-adjusted MDA concentrations increased from 0.55 to 0.73 mumol/L as GI increased from the lowest to the highest quartile (P for trend = 0.02); the corresponding IsoP concentrations increased from 0.034 to 0.040 ng/mL (P for trend = 0.03). GL was positively associated with both MDA and IsoPs, but the linear relation was significant only for MDA. In addition, a marginally significant interaction between overall GI and body mass index (BMI; in kg/m(2)) for plasma MDA was observed (P = 0.09). The positive association between overall GI and MDA was stronger in those with a BMI < 26.5 than for those with a BMI >/= 26.5. CONCLUSIONS: Chronic consumption of high-GI foods may lead to chronically high oxidative stress. A low-GI diet, not a low-carbohydrate diet, appears to be beneficial in reducing oxidative stress. Copyright © 2006 American Society for Nutrition [ABSTRACT FROM AUTHOR]

BACKGROUND: Free radicals in cigarette smoke may cause oxidative damage to macromolecules, contributing to cardiovascular diseases and cancer. Decreased plasma antioxidant concentrations may indicate cigarette smoke-related oxidative stress. OBJECTIVE: We compared the effects on plasma antioxidant concentrations in cotinine-confirmed active and passive smokers with those in nonsmokers, independent of differences in dietary intakes and other covariates. DESIGN: Plasma samples from 83 smokers, 40 passive smokers, and 36 nonsmokers were analyzed for total ascorbic acid, alpha- and gamma-tocopherols, 5 carotenoids, retinol, and cotinine. Groups were compared by using analysis of variance with adjustment for sex, age, race, body mass index, alcohol intake, triacylglycerol concentration, fruit and vegetable intakes, and dietary antioxidants. RESULTS: After adjustment for dietary antioxidant intakes and other covariates, smokers and passive smokers had significantly lower plasma beta-carotene concentrations than did nonsmokers (0.15, 0.17, and 0.24 micro mol/L, respectively) and significantly higher gamma-tocopherol concentrations (7.8, 7.8, and 6.5 micro mol/L, respectively). Smokers had significantly lower plasma ascorbic acid and beta-cryptoxanthin concentrations than did nonsmokers and passive smokers (ascorbic acid: 43.6, 54.5, and 54.6 micro mol/L, respectively; beta-cryptoxanthin: 0.12, 0.16, and 0.16 micro mol/L, respectively) and significantly lower concentrations of lutein and zeaxanthin than did nonsmokers (0.33 compared with 0.41 micro mol/L). The P values for all the differences described above were < 0.05. No significant differences in plasma concentrations of alpha-tocopherol, alpha-carotene, total carotenoids, lycopene, or retinol were observed. CONCLUSIONS: These results indicate that cigarette smokers and nonsmokers exposed to cigarette smoke have a significantly lower plasma antioxidant status than do unexposed nonsmokers, independent of differences in dietary antioxidant intakes. Further research is required to explain why plasma gamma-tocopherol concentrations were significantly higher in smokers and passive smokers than in nonsmokers. [ABSTRACT FROM AUTHOR]

Adequate nutrition is critical during long-term spaceflight, as is the ability to easily monitor dietary intake. A comprehensive nutritional status assessment profile was designed for use before, during and after flight. It included assessment of both dietary intake and biochemical markers of nutritional status. A spaceflight food-frequency questionnaire (FFQ) was developed to evaluate intake of key nutrients during spaceflight. The nutritional status assessment protocol was evaluated during two ground-based closed-chamber studies (60 and 91 d; n = 4/study), and was implemented for two astronauts during 4-mo stays on the Mir space station. Ground-based studies indicated that the FFQ, administered daily or weekly, adequately estimated intake of key nutrients. Chamber subjects maintained prechamber energy intake and body weight. Astronauts tended to eat 40--50% of WHO-predicted energy requirements, and lost >10% of preflight body mass. Serum ferritin levels were lower after the chamber stays, despite adequate iron intake. Red blood cell folate concentrations were increased after the chamber studies. Vitamin D stores were decreased by > 40% on chamber egress and after spaceflight. Mir crew members had decreased levels of most nutritional indices, but these are difficult to interpret given the insufficient energy intake and loss of body mass. Spaceflight food systems can provide adequate intake of macronutrients, although, as expected, micronutrient intake is a concern for any closed or semiclosed food system. These data demonstrate the utility and importance of nutritional status assessment during spaceflight and of the FFQ during extended-duration spaceflight. [ABSTRACT FROM AUTHOR]

A letter to the editor related to role of Vitamin C in inhibition of N-nitroso compound formation is presented.

A response by G. A. Block, D. Spiegel and P. Raggie to a letter to the editor about their article "Mortality effect of coronary calcification and phosphate binder choice in incident hemodialysis patients" in the previous issue.

Reports on the result of a study about the effects of the use of regular supplement to serum vitamin C levels.

Abstract: Increased aortic stiffness, as measured by pulse wave velocity (PWV) and augmentation index (Aix), and vascular calcification have been associated with an unfavourable cardiovascular outcome in hemodialysis patients. However, the majority of data have been published in white patients and epidemiological data are discordant on the fate of patients of different races. In this cross sectional study we measured PWV and Aix by applanation tonometry and coronary artery and thoracic aorta calcium score (CAC and AoC) by electron beam tomography (EBT) in 81 Blacks and 61 Whites on maintenance hemodialysis. Vascular stiffness measurements and EBT scans were performed within a week of each other. There was no difference between races in age, systolic blood pressure or gender distribution. Blacks had a more frequent history of hypertension (100% versus 89%; P =0.002), lower prevalence of dyslipidemia (30% versus 66%; P <0.001), higher PTH levels (geometric mean 607pg/ml versus 245pg/ml; P =0.039), received calcium based phosphate binders less frequently (37% versus 60%, P =0.007) and calcium antagonists more frequently than Whites (54% versus 28%; P =0.003). Nonetheless, the unadjusted and risk adjusted PWV and Aix, as well as CAC and AoC were not statistically different between races. In this dialysis cohort there was no difference in markers of vasculopathy between black and white patients despite differences in baseline clinical characteristics. Epidemiological data from the general population indicate that Blacks have lower calcium scores and stiffer vessels than Whites. Some studies in the renal populations suggest a better and others a similar survival of Blacks and Whites on hemodialysis. Our findings raise the important question of the prognostic significance of markers of vasculopathy in patients of different races and with different risk profiles. [Copyright &y& Elsevier]

The recent Kidney Disease: Improving Quality Outcomes (KDIGO) recommendations called for an investigation of the relationship between various radiological methods to assess cardiovascular calcification and measures of arterial stiffness. Accordingly, in 131 adult maintenance hemodialysis patients, we investigated the association of aortic pulse wave velocity (PWV) with calcification of cardiac valves on echocardiography, coronary artery, and thoracic aorta calcium on computed tomography and a calcification score of the abdominal aorta obtained on a plain abdominal X-ray. All tests were performed within a week. Mean PWV increased as the severity of coronary artery, thoracic, and abdominal aorta calcium scores increased (each P<0.05). No trend was present for number of valves with calcification. After multivariable adjustment, abdominal aorta X-ray calcium scores remained associated with PWV (P=0.004), whereas the association of PWV with thoracic aorta and coronary artery calcium scores became marginal (P=0.308 and P=0.083, respectively). No association was found between number of calcified valves and PWV. This study demonstrates a strong association between abdominal aorta calcification on plain X-ray and PWV and a borderline association with thoracic aorta and coronary artery calcification. Sudden death and congestive heart failure, two frequent causes of death in hemodialysis, are likely caused by increased arterial stiffness that can be closely predicted by the presence of aortic calcification on plain X-rays.Kidney International (2007) 71, 802–807. doi:10.1038/sj.ki.5002164; published online 21 February 2007 [ABSTRACT FROM AUTHOR]

Vascular calcification is associated with an adverse prognosis in end-stage renal disease. It can be accurately quantitated with computed tomography but simple in-office techniques may provide equally useful information. Accordingly we compared the results obtained with simple non-invasive techniques with those obtained using electron beam tomography (EBT) for coronary artery calcium scoring (CACS) in 140 prevalent hemodialysis patients. All patients underwent EBT imaging, a lateral X-ray of the lumbar abdominal aorta, an echocardiogram, and measurement of pulse pressure (PP). Calcification of the abdominal aorta was semiquantitatively estimated with a score (Xr-score) of 0–24 divided into tertiles, echocardiograms were graded as 0–2 for absence or presence of calcification of the mitral and aortic valve and PP was divided in quartiles. The CACS was elevated (mean 910±1657, median 220). The sensitivity and specificity for CACS100 was 53 and 70%, for calcification of either valve and 67 and 91%, respectively, for Xr-score 7. The area under the curve for CACS100 associated with valve calcification and Xr-score was 0.62 and 0.78, respectively. The likelihood ratio (95% confidence interval) of CACS100 was 1.79 (1.09, 2.96) for calcification of either valve and 7.50 (2.89, 19.5) for participants with an Xr-score 7. In contrast, no association was present between PP and CACS. In conclusion, simple measures of cardiovascular calcification showed a very good correlation with more sophisticated measurements obtained with EBT. These methodologies may prove very useful for in-office imaging to guide further therapeutic choices in hemodialysis patients.Kidney International (2006) 70, 1623–1628. doi:10.1038/sj.ki.5001820; published online 6 September 2006 [ABSTRACT FROM AUTHOR]