Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies of steroids and plasma lipoproteins in male cigarette smokers reveal that smoking is associated with an increase in peripheral estrogens and a decrease in high-density lipoprotein-cholesterol (HDL-C). We hypothesized that the lower HDL-C in this setting results in part from induction of the hepatic metabolic pathway that inactivates estrogen. This pathway, estradiol 2-hydroxylation, produces the peripherally inactive catechol estrogens 2-hydroxyesterone and 2-methoxyestrone. We used an in vivo radiometric method to assess 2-hydroxylation in 20 male smokers and 16 nonsmokers. The extent of the reaction (+/- SEM) was significantly higher among the smokers (43.3% +/- 1.9% v 24.6% +/- 1.9%, P less than .001). Smokers also excreted more urinary 2-hydroxyestrone (10.4 +/- 1.3 micrograms/g creatinine v 6.3 +/- 0.73 micrograms/g in nonsmokers, P = .011). The ratio of urinary 2-hydroxyestrone to estriol was higher on average among smokers (1.46 +/- 0.19 v 0.81 +/- 0.11, P = .006), and individual values correlated well with the radiometric test (r = .71, P less than .002). These data indicate that smoking is associated with significantly increased estrogen 2-hydroxylation in men. Preliminary evidence suggests that the smoking effect on C-2 hydroxylation may be opposed by ethanol. Elevated 2-hydroxylation in smokers, in the setting of modestly increased peripheral estrogens and a net decrease in HDLC, may be explained by the fact that lipoprotein synthesis and estrogen 2-hydroxylation both occur predominantly in the liver. Thus, greater metabolic inactivation of hepatic estrogens in male smokers could reduce HDLC, despite a modest rise in circulating hormone levels.
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PMID:Cigarette smoking alters hepatic estrogen metabolism in men: implications for atherosclerosis. 272 92

In the present study, the immersion behavior of two kinds of sintered HA with different Ca/P ratios in two different extracellular simulated solutions (Tris buffer and Hank's solutions) was investigated and compared. Results indicated that an as-received Ca-deficient HA (FHA) had a lower Ca/P ratio, larger linear shrinkage and higher density than a stoichiometric HA (MHA). When FHA powder was calcined at 900 degrees C, its Ca-deficient apatite structure was unstable and a significant amount of beta-TCP phase was formed. When heated to 1250 degrees C in air, the highly crystalline apatite structure of MHA was still stable without any noticeable decomposition. The FTIR spectra indicated that both immersed MHA and FHA in Hank's solution were gradually covered with a layer of precipitated apatite during immersion. When immersed in Tris buffer solution, neither HA showed significant changes in their FTIR spectra. SEM observation indicated that the precipitation rate on immersed FHA surface was much higher than that on MHA surface when immersed in Hank's solution. The weight loss and pH data confirmed the higher dissolution rate of FHA than MHA in Hank's solution.
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PMID:Surface reaction of stoichiometric and calcium-deficient hydroxyapatite in simulated body fluid. 1534 46