Hypovitaminosis D in patients undergoing kidney transplant: the importance of sunlight exposure

OBJECTIVES: Recent studies have shown a high prevalence of hypovitaminosis D, defined as a serum 25-hydroxyvitamin D level less than 30 ng/ml, in both healthy populations and patients with chronic kidney disease. Patients undergoing kidney transplant are at an increased risk of skin cancer and are advised to avoid sunlight exposure. Therefore, these patients might share two major risk factors for hypovitaminosis D: chronic kidney disease and low sunlight exposure. This paper describes the prevalence and clinical characteristics of hypovitaminosis D among patients undergoing kidney transplant. METHODS: We evaluated 25-hydroxyvitamin D serum levels in a representative sample of patients undergoing kidney transplant. We sought to determine the prevalence of hypovitaminosis D, compare these patients with a control group, and identify factors associated with hypovitaminosis D (e.g., sunlight exposure and dietary habits). RESULTS: Hypovitaminosis D was found in 79% of patients undergoing kidney transplant, and the major associated factor was low sunlight exposure. These patients had higher creatinine and intact parathyroid hormone serum levels, with 25-hydroxyvitamin D being inversely correlated with intact parathyroid hormone serum levels. Compared with the control group, patients undergoing kidney transplant presented a higher prevalence of 25-hydroxyvitamin D deficiency and lower serum calcium, phosphate and albumin but higher creatinine and intact parathyroid hormone levels. CONCLUSIONS: Our results confirmed the high prevalence of hypovitaminosis D in patients undergoing kidney transplant. Therapeutic strategies such as moderate sunlight exposure and vitamin D supplementation should be seriously considered for this population

Bone Plasticity in Response to Exercise Is Sex-Dependent in Rats

Purpose: To characterize the potential sexual dimorphism of bone in response to exercise.Methods: Young male and female Wistar rats were either submitted to 12 weeks of exercise or remained sedentary. the training load was adjusted at the mid-trial (week 6) by the maximal speed test. A mechanical test was performed to measure the maximal force, resilience, stiffness, and fracture load. the bone structure, formation, and resorption were obtained by histomorphometric analyses. Type I collagen (COL I) mRNA expression and tartrate-resistant acid phosphatase (TRAP) mRNA expression were evaluated by quantitative real-time PCR (qPCR).Results: the male and female trained rats significantly improved their maximum speed during the maximal exercise test (main effect of training; p<0.0001). the male rats were significantly heavier than the females, irrespective of training (main effect of sex; p<0.0001). Similarly, both the weight and length of the femur were greater for the male rats when compared with the females (main effect of sex; p<0.0001 and p<0.0001, respectively). the trabecular volume was positively affected by exercise in male and female rats (main effect of training; p = 0.001), whereas the trabecular thickness, resilience, mineral apposition rate, and bone formation rate increased only in the trained males (within-sex comparison; p<0.05 for all parameters), demonstrating the sexual dimorphism in response to exercise. Accordingly, the number of osteocytes increased significantly only in the trained males (within-sex comparison; p<0.05). Pearson's correlation analyses revealed that the COL I mRNA expression and TRAP mRNA expression were positively and negatively, respectively, related to the parameters of bone remodeling obtained from the histomorphometric analysis (r = 0.59 to 0.85; p<0.05).Conclusion: Exercise yielded differential adaptations with respect to bone structure, biomechanical proprieties, and molecular signaling in male and female rats.Univ São Paulo, Sch Med, Div Nephrol, São Paulo, BrazilUniv São Paulo, Sch Phys Educ & Sport, Dept Sports, São Paulo, BrazilUniv São Paulo, Inst Biomed Sci, Dept Anat, São Paulo, BrazilUniv São Paulo, Sch Med, Div Rheumatol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Physiol Sci, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Physiol Sci, São Paulo, BrazilWeb of Scienc

Serum sclerostin is an independent predictor of mortality in hemodialysis patients

Background\ud Sclerostin (Scl) has recently emerged as a novel marker of bone remodeling and vascular calcification. However, whether high circulating Scl is also a risk factor for death is not well established. The purpose of this study was to test whether serum Scl would be associated with mortality.\ud \ud \ud Methods\ud we measured serum Scl in a hemodialysis patients’ cohort, which was followed during a ten-year period. Competing risk regression models were applied, as during the follow-up, patients were exposed to both events kidney transplant and death.\ud \ud \ud Results\ud Ninety-one patients aged 42.3 ± 18.8 years (55% of male gender, 15% of diabetes) were included. During the follow-up, 32 patients underwent kidney transplant and 26 patients died. Non-survivals presented higher FGF23, higher Scl and lower creatinine. There was an association between all-cause mortality and higher Scl (HR = 2.2), higher age (HR = 1.04) and presence of diabetes (HR = 2.27), by competing risk analyses. Even including potential markers of mortality, as creatinine, FGF 23, and gender, Scl, age and diabetes remained significantly related to higher mortality.\ud \ud \ud Conclusion\ud Serum Scl is an independent predictor of mortality in dialysis patients. However, whether clinical interventions to modulate Scl would be able to improve these patients survival needs to be determined.Fapes

Mineral bone disorder in chronic kidney disease: head-to-head comparison of the 5/6 nephrectomy and adenine models

Abstract\ud \ud Background\ud Experimental models are important to the understanding of the pathophysiology of, as well as the effects of therapy on, certain diseases. In the case of chronic kidney disease-mineral bone disorder, there are currently two models that are used in evaluating the disease: 5/6 nephrectomy (Nx) and adenine-induced renal failure (AIRF). However, the two models have never been compared in studies using animals maintained under similar conditions. Therefore, we compared these two models, focusing on the biochemical, bone histomorphometry, and vascular calcification aspects.\ud \ud \ud Methods\ud Wistar rats, initially fed identical diets, were divided into two groups: those undergoing 5/6 Nx (5/6Nx group) and those that were switched to an adenine-enriched diet (AIRF group). After 9 weeks, animals were sacrificed, and we conducted biochemical and bone histomorphometry analyses, as well as assessing vascular calcification.\ud \ud \ud Results\ud At sacrifice, the mean body weight was higher in the 5/6Nx group than in the AIRF group, as was the mean blood pressure. No differences were seen regarding serum phosphate, ionized calcium, intact parathyroid hormone (PTH), or fibroblast growth factor 23 (FGF23). However, creatinine clearance was lower and fractional excretion of phosphate (FeP) was higher in the AIRF group rats, which also had a more severe form of high-turnover bone disease. Vascular calcification, as evaluated through von Kossa staining, was not observed in any of the animals.\ud \ud \ud Conclusions\ud Overt vascular calcification was not seen in either model as applied in this study. Under similar conditions of diet and housing, the AIRF model produces a more severe form of bone disease than does 5/6 Nx. This should be taken into account when the choice is made between these models for use in preclinical studies.This study was supported by Fresenius Medical Care Deutschland GmbH,\ud Germany and Fapesp (grant 2008/53147-0). RMAM is supported by CNPQ,\ud Conselho Nacional de Desenvolvimento Científico e Tecnológico (grant\ud 303325/2010-0). It was presented in part at the ASN Kidney Week 2011

Valor nutritivo de pastagens de capim-elefante manejadas sob sistema convencional e agroecológico.

O capim-elefante é utilizado, na sua grande maioria, em sistemas convencionais de produção animal. O objetivo deste trabalho foi comparar o valor nutritivo do capimelefante em sistemas de manejo agroecológico e convencional, quanto a proteína bruta (PB), fibra em detergente neutro (FDN) e digestibilidade in vitro da matéria seca (DIVMS). Foram usados quatro piquetes, com 0,12ha cada um. No sistema convencional, o capim-elefante foi estabelecido singularmente. No sistema agroecológico, o plantio foi feito em linhas afastadas de 3m. Nas entrelinhas, estabeleceu-se a aveia e o azevém no período hibernal, enquanto que no período estival permitiu-se o desenvolvimento de espécies espontâneas. A adubação foi feita com fertilizantes orgânicos (150kg ha-1 de N). No sistema agroecológico, foram conduzidos sete pastejos, de 24/04/2004 a 05/05/2005. Na pastagem convencional, usouse a mesma quantidade de N (uréia), sendo conduzidos quatro ciclos de pastejo, de 06/10/2004 a 05/05/2005. Para ambos os sistemas foram utilizadas vacas da raça Holandês, recebendo complementação alimentar de 3,5kg dia-1 de concentrado com 20% de proteína bruta, constituindo-se nos animais experimentais. Nas avaliações, considerou-se a massa de forragem inicial com base na matéria seca (MS), os componentes botânicos da pastagem e estruturais do capimelefante. As análises de qualidade foram feitas em amostras de pastejo simulado. O delineamento experimental foi o inteiramente casualizado com dois tratamentos, convencional e agroecológico, duas repetições (piquetes) e em parcelas incompletas subdivididas no tempo (pastejos). Houve interação (P<0,05) entre tratamentos e pastejos em todas as variáveis. Na pastagem agroecológica, o modelo que melhor se ajustou foi o cúbico para todas as variáveis, em função do tempo de pastejo. Na pastagem convencional, a PB e a DIVMS ajustaram-se melhor ao modelo linear, com taxa positiva de crescimento, sendo observado comportamento inverso para FDN, com o decorrer dos pastejos. Tanto na pastagem convencional quanto na agroecológica encontraram-se associações negativas entre lâmina foliar do capim-elefante com PB e DIVMS e positiva com FDN. Ambos os sistemas apresentaram teores qualitativos elevados das pastagens, considerando-se a adubação, o manejo e o tempo de utilização

Phosphorus Is Associated with Coronary Artery Disease in Patients with Preserved Renal Function

High serum phosphorus levels have been associated with mortality and cardiovascular events in patients with chronic kidney disease and in the general population. In addition, high phosphorus levels have been shown to induce vascular calcification and endothelial dysfunction in vitro. The aim of this study was to evaluate the relation of phosphorus and coronary calcification and atherosclerosis in the setting of normal renal function. This was a cross-sectional study involving 290 patients with suspected coronary artery disease and undergoing elective coronary angiography, with a creatinine clearance >60 ml/min/1.73 m2. Coronary artery obstruction was assessed by the Friesinger score and coronary artery calcification by multislice computed tomography. Serum phosphorus was higher in patients with an Agatston score >10 than in those with an Agatston score ≤10 (3.63±0.55 versus 3.49±0.52 mg/dl; p = 0.02). In the patients with Friesinger scores >4, serum phosphorus was higher (3.6±0.5 versus 3.5±0.6 mg/dl, p = 0.04) and median intact fibroblast growth factor 23 was lower (40.3 pg/ml versus 45.7 pg/ml, p = 0.01). Each 0.1-mg/dl higher serum phosphate was associated with a 7.4% higher odds of having a Friesinger score >4 (p = 0.03) and a 6.1% greater risk of having an Agatston score >10 (p = 0.01). Fibroblast growth factor 23 was a negative predictor of Friesinger score (p = 0.002). In conclusion, phosphorus is positively associated with coronary artery calcification and obstruction in patients with suspected coronary artery disease and preserved renal function

Predictive Factors of One-Year Mortality in a Cohort of Patients Undergoing Urgent-Start Hemodialysis.

BACKGROUNDChronic kidney disease (CKD) affects 10-15% of adult population worldwide. Incident patients on hemodialysis, mainly those on urgent-start dialysis at the emergency room, have a high mortality risk, which may reflect the absence of nephrology care. A lack of data exists regarding the influence of baseline factors on the mortality of these patients. The aim of this study was to evaluate the clinical and laboratory characteristics of this population and identify risk factors that contribute to their mortality.PATIENTS AND METHODSWe studied 424 patients who were admitted to our service between 01/2006 and 12/2012 and were followed for 1 year. We analyzed vascular access, risk factors linked to cardiovascular disease (CVD) and mineral and bone disease associated with CKD (CKD-MBD), and clinical events that occurred during the follow-up period. Factors that influenced patient survival were evaluated by Cox regression analysis.RESULTSThe patient mean age was 50 ± 18 years, and 58.7% of them were male. Hypertension was the main cause of primary CKD (31.8%). Major risk factors were smoking (19.6%), dyslipidemia (48.8%), and CVD (41%). Upon admission, most patients had no vascular access for hemodialysis (89.4%). Biochemical results showed that most patients were anemic with high C-reactive protein levels, hypocalcemia, hyperphosphatemia, elevated parathyroid hormone and decreased 25-hydroxy vitamin D. At the end of one year, 60 patients died (14.1%). These patients were significantly older, had a lower percentage of arteriovenous fistula in one year, and low levels of 25-hydroxy vitamin D.CONCLUSIONSThe combined evaluation of clinical and biochemical parameters and risk factors revealed that the mortality in urgent-start dialysis is associated with older age and low levels of vitamin D deficiency. A lack of a permanent hemodialysis access after one year was also a risk factor for mortality in this population