The Vitamin D 25-Hydroxylase

Gascon-Barré, Marielle

doi:10.1016/b978-012252687-9/50007-3

Cited by 11 publications

(6 citation statements)

References 159 publications

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“…A number of cytochrome P450 (CYP) enzymes, both mitochondrial and microsomal, are involved, among which CYP27A1 and CYP2R1 are the best known and studied [1,8]. CYP27A1 and related enzymes are most abundantly present in the liver, but other organs are also capable of converting pre-vitamin D to 25(OH)D for local effects [9]. 25(OH)D 2 (calcidiol) and 25(OH)D 3 (ercalcidiol) behave in a similar manner and are subsequently referred to here only as 25(OH)D. 25(OH)D production is primarily substrate dependent, and, very importantly, there is no negative feedback control of this step.…”

Section: Vitamin D Metabolismmentioning

confidence: 99%

The virtues of vitamin D—but how much is too much?

2010

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Vitamin D deficiency is common in healthy adults and children as well as in the chronic kidney disease (CKD) population. What was once a disease of malnourished children in the developing world has re-emerged and reached pandemic proportions. In parallel with this development, there is a growing awareness that vitamin D is not simply a 'calcaemic hormone' but plays an important role in the prevention of cardiovascular disease, infectious and auto-immune conditions, renoprotection, glycaemic control and prevention of some common cancers. Most tissues in the body have a vitamin D receptor and the enzymatic machinery to convert 'nutritional' 25-hydroxyvitamin D to the active form 1,25-dihydroxyvitamin D; it is estimated that 3% of the human genome is regulated by the vitamin D endocrine system. Although there are few well-conducted studies on the benefits of vitamin D therapy, an exuberant use of vitamin D is now seen in the general population and at all stages of CKD. There is emerging evidence that vitamin D may in fact have a therapeutic window, and at least from the effects on the cardiovascular system, more is not necessarily better. In this review, we discuss the role of nutritional vitamin D (ergocalciferol or cholecalciferol) supplementation in CKD patients, interpreting the clinical studies in the light of the vitamin D metabolic pathway and its pluripotent effects. While nutritional vitamin D compounds clearly have numerous beneficial effects, randomised controlled studies are required to determine the effectiveness and optimal dose at different stages of CKD, its concurrent use with activated vitamin D compounds and its safety profile.

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Section: Vitamin D Metabolismmentioning

confidence: 99%

The virtues of vitamin D—but how much is too much?

2010

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“…1 результати показу-ють, що за введення преднізолону вміст 25ОНD 3 в сироватці крові зменшується у 3 рази порівняно з контролем. За такого рівня 25ОНD 3 [16,17]. Мітохондріальна вітамін D 3 25-гідроксилаза (CYP27A1), яка локалізована на внутрішній поверхні мем-брани, має низьку специфічність, але висо-ку ємність зв'язування субстрату.…”

Section: результати та обговоренняunclassified

Cholecalciferol hydroxylation in rat hepatocytes under the influence of prednisolone

Khomenko¹

2013

Ukr.Biochem.J.

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“…These enzymes are found in many tissues, and their activity is limited primarily by substrate, ie. vitamin D, availability [8] . As such, serum 25OHD is a reliable indicator of vitamin D status [9].…”

Section: Vitamin D Metabolismmentioning

confidence: 99%

Vitamin D: newly discovered actions require reconsideration of physiologic requirements

Bikle

2010

Trends in Endocrinology & Metabolism

142

122

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Vitamin D is not just for preventing rickets and osteomalacia. Recent findings in animal experiments, epidemiologic studies and clinical trials, indicate that adequate vitamin D levels are important for cancer prevention, controlling hormone levels, and regulating the immune response. Although 25 Hydroxyvitamin D (25OHD) levels above 10ng/ml may prevent rickets and osteomalacia, these levels are not sufficient to provide these more recently discovered clinical benefits. Rather, levels of 25OHD above 30ng/ml are generally recommended. Determining optimal levels of 25OHD and the amount of vitamin D supplementation required to achieve those levels for the numerous actions of vitamin D will only be established with additional trials. In this review, these newer applications are summarized and therapeutic considerations provided.

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The Vitamin D 25-Hydroxylase

Cited by 11 publications

References 159 publications

The virtues of vitamin D—but how much is too much?

The virtues of vitamin D—but how much is too much?

Cholecalciferol hydroxylation in rat hepatocytes under the influence of prednisolone

Vitamin D: newly discovered actions require reconsideration of physiologic requirements

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