The link between vascular calcification (VC) and increased mortality is now well established. Over time, as clinical importance of this phenomenon has begun to be fully considered, scientists have highlighted more and more physiopathological mechanisms and signaling pathways that underlie VC. Several conditions such as diabetes, dyslipidemia and renal diseases are undoubtedly identified as predisposing factors. But even if the process is better understood, many questions still remain unanswered. This review briefly develops the various theories that attempt to explain mineralization genesis. Nonetheless, the main purpose of the article is to provide a profile of the various existing biomarkers of VC. Indeed, in the past years, a lot of inhibitors and promoters, which form a dense and interconnected network, were identified. Given importance to assess and control mineralization process, a focusing on accumulated knowledge of each marker seemed to be necessary. Therefore, we tried to define their respective role in the physiopathology and how they can contribute to calcification risk assessment. Among these, Klotho/fibroblast growth factor-23, fetuin-A, Matrix Gla protein, Bone morphogenetic protein-2, osteoprotegerin, osteopontin, osteonectin, osteocalcin, pyrophosphate and sclerostin are specifically discussed.
Cord serum 25(OH)D levels were inversely associated with the risk of transient early wheezing and atopic dermatitis by the age of 5 years, but no association was found with asthma and allergic rhinitis.
Very few studies have investigated the determinants of serum vitamin D levels using a set of variables that include simultaneously sun exposure, phototype, dietary intake, sociodemographics, anthropometric, lifestyle data, and genetic polymorphisms. Our objective was to investigate the associations between all these parameters and vitamin D status in a large sample of French adults. This cross-sectional survey was based on 1,828 middle-aged Caucasian adults from the SU.VI.MAX (SUpplémentation en VItamines et Minéraux AntioXydants) study. Plasma 25-hydroxyvitamin D (25OHD) concentration was lower among women (P<0.0001), older subjects (P=0.04), obese/underweight (P<0.0001), those living at higher latitudes (P<0.0001), those whose blood draw occurred in early spring (P<0.0001), less physically active (P<0.0001), with low sun exposure (P<0.0001), and with no-to-low alcohol intake (P=0.0001). Mutant GC rs4588 and rs7041 single nucleotide polymorphisms were associated with lower and higher 25OHD concentrations, respectively (P<0.0001). Dietary intake was not a major determinant of vitamin D status (P=0.7). This study provides an overall picture of determinants of vitamin D status. Several modifiable factors were identified, such as daily-life moderate sun exposure, physical activity, and normal-weight maintenance, which should be targeted by public health policies in order to improve vitamin D status in the general population, while avoiding active/intensive sun exposure, in line with recommendations for skin cancer prevention.
25(OH)D deficiency was frequent in HIV-infected persons (83% on combined antiretroviral therapy), and was independently associated with a higher risk of mortality and AIDS events. Causality relationships should be examined, because of potential public health consequences.
In our population, AP2S1 mutations affect calcium homeostasis more severely than CASR mutations. Due to overlap, the risk of confusion between FHH and PHPT is high.
In addition to classic risk factors, the degree of atherosclerosis and vascular calcification in our dialysis patient population were associated with several factors that are frequently abnormal in advanced chronic renal failure, but except age, all of them were interdependent. Notably, as in the general population, CACS was an independent predictor of the degree of atherosclerosis in haemodialysis patients.
The most recent findings linking exposure to sun and vitamin D insufficiency to multiple sclerosis (MS) are reviewed. Due to insufficient sunshine and changing lifestyles, hypovitaminosis D is widespread in temperate countries. Numerous epidemiological studies have strongly suggested that sunshine and vitamin D insufficiency contributes to MS risk in these countries. Moreover, several large genetic studies in MS patients have recently stated unequivocally that diverse abnormalities involving vitamin D metabolism are related to the risk of the disease. The important implications of such results are discussed here. Then, the interactions of hypovitaminosis D with the other genetic and environmental protective and risk factors, such as the allele HLA DRB1*1501, Epstein-Barr virus infection, obesity, smoking and sexual hormones, are summarized. Vitamin D insufficiency and sufficiency could be a risk and a protective factor, respectively, among many other factors possibly continuously modulating the global MS risk from the mother's pregnancy to the triggering of MS in adulthood. However, many interactions between these different factors occur more particularly between conception and the end of adolescence, which corresponds to the period of maturation of the immune system and thymus and may be related to the dysimmune nature of the disease. The main mechanisms of action of vitamin D in MS appear to be immunomodulatory, involving the various categories of T and B lymphocytes in the general immune system, but neuroprotector and neurotrophic mechanisms could also be exerted at the central nervous system level. Furthermore, several controlled immunological studies performed in MS patients have recently confirmed that vitamin D supplementation has multiple beneficial immunomodulatory effects. However, there is still an enduring absence of major conclusive randomized clinical trials testing vitamin D supplementation in MS patients because of the quasi-insurmountable practical difficulties that exist nowadays in conducting and completing over several years such studies involving the use of a vitamin. Nevertheless, it should be noted that similar robust statistical models used in five different association studies have already predicted a favorable vitamin D effect reducing relapses by 50-70%. If there is now little doubt that vitamin D exerts a beneficial action on the inflammatory component of MS, the results are as yet much less clear for the progressive degenerative component. Lastly, until more information becomes available, vitamin D supplementation of MS patients, using a moderate physiological dose essentially correcting their vitamin insufficiency, is recommended.
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