The mitochondrial 25-hydroxylase is now well accepted as CYP27A1, an enzyme first identified as catalyzing a critical step in the bile acid synthesis pathway. This is a high capacity, low affinity enzyme consistent with the observation that 25-hydroxylation is not generally rate limiting in vitamin D metabolism. Although initial studies suggested that the vitamin D 3 -25-hydroxylase and cholestane triol 27-hydroxyase activities in liver mitochondria were due to distinct enzymes with differential regulation, the cloning of CYP27A1 and the demonstration that it contained both activities has put this issue to rest [18-20]. CYP27A1 is widely distributed throughout different tissues with highest levels in liver and muscle, but also in kidney, intestine, lung, skin, and bone [18-21]. Mutations in CYP27A1 lead to cerebrotendinous xanthomatosis [22, 23], and are associated with abnormal vitamin D and/or calcium metabolism in some but not all of these patients [23-25]. However, mice in which CYP27A1 is deleted actually have elevated 25OHD levels along with the disruption in bile acid synthesis . CYP27A1 can hydroxylate vitamin D and related compounds at the 24, 25, and 27 positions. However, D 2 appears to be preferentially 24-hydroxylated, whereas D 3 is preferentially 25-hydroxylated . The 1αOH derivatives of D are more rapidly hydroxylated than the parent compounds(30). These differences between D 2 and D 3 and their 1αOH derivatives may explain the differences in biologic activity between D 2 and D 3 or between 1αOHD 2 and 1αOHD 3 .
This is my second time using this particular Lab. I've previous positive experience with Sis (when formerly known as Infiniti Labs) Anavar, so my expectations were some what inflated:)
Firstly, I was really impressed by the immaculate packaging of this product, which shows how much effort went into its manufacturing and marketing. I ran this product at a weekly dose of 400mg, in conjunction with Mast e and Test. Prior to introducing Sis Tren e into my current cycle, I was already using a different Labs Tren at a slightly higher dose of 500mg weekly. To be honest, I did not notice any difference, even when running Sis Tren e at a slightly lowered dose of 400mg for 5 weeks in total. I continued with making strength gains with a noticeable reduction in body fat, even though my diet wasn't always on point. I have had no adverse effects from the Tren, unless if you want to include night sweats. Overall, I am very satisfied with the results I got from use of this product.