Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.177 (BIS)
 957 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of intermittent low doses (1.25 mug daily, administered intravenously for 6 days and withdrawn for 14 days for 3 complete cycles) of 1,25-dihydroxycholecalciferol (1,25-[OH](2)D(3)) on cortical bone were determined and compared in ribs with steady state and regionally accelerated remodeling in adult intact female dogs. The bone changes were analyzed by dynamic bone histomorphometric methods, using tetracycline and DCAF (2,4 BIS) N, N' di (carboxymethyl) (amino methyl fluorescein) in vivo double labeling of bones before treatment and after 60 days of intermittent 1,25-(OH)(2)D(3) administration. Serum calcium and phosphorus levels increased during 1,25-(OH)(2)D(3) administration. Urinary hydroxyproline excretion increased during the first interval of 1,25-(OH)(2)D(3) administration but was not changed significantly during the last two intervals. In normal cortical bone (11th rib) following the administration of 1,25-(OH)(2)D(3) there was a marked decrease in the activation frequency, bone formation rate, osteoid seam thickness, seam circumference, and mean appositional rate. Although recruitment of new remodeling sites was decreased after 1,25-(OH)(2)D(3), previously existing remodeling units continued to completion. These effects resulted in a preponderance of mature osteons in normal cortical bone. The morphometric changes in cortical bone (9th rib) exposed to both 1,25-(OH)(2)D(3) and periosteal elevation were characterized by a marked increase in both the activation frequency and bone formation rate and associated with a decrease in the osteon formation time. Other morphometric parameters that were increased included radial closure rate, numbers of osteoid seams and resorption cavities, ratio of bone resorbing to forming sites, percentage labeled and circumference of osteoid seams, and total and cortical bone areas. The combined effect of periosteal elevation and 1,25-(OH)(2)D(3) were markedly different from those observed with 1,25-(OH)(2)D(3) alone. These findings suggest that the rapid bone turnover induced by tissue injury will mask or alter the effects of hormones on bone remodeling when studied over a relatively short period of time.
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PMID:Histomorphometric evaluation of the effects of intermittent 1,25-dihydroxycholecalciferol administration on cortical bone remodeling in adult dogs. 689 23

Buffering compounds like TRIS are frequently used in chemical, biochemical and biomedical applications to control pH in solution. One of the prerequisites of a buffer compound, in addition to sufficient buffering capacity and pH stability over time, is its non-reactivity with other constituents of the solution. This is especially important in the field of analytical chemistry where analytes are to be determined quantitatively. Investigating the enzymatic hydrolysis of G-type nerve agents sarin, soman and cyclosarin in buffered solution we have identified stable buffer adducts of TRIS, TES and other buffer compounds with the nerve agents. We identified the molecular structure of these adducts as phosphonic diesters using 1D (1)H-(31)P HSQC NMR and LC-ESI-MS/MS techniques. Reaction rates with TRIS and TES are fast enough to compete with spontaneous hydrolysis in aqueous solution and to yield substantial amounts (up to 20-40%) of buffer adduct over the course of several hours. A reaction mechanism is proposed in which the amino function of the buffer serves as an intramolecular proton acceptor rendering the buffer hydroxyl groups nucleophilic enough for attack on the phosphorus atom of the agents. Results show that similar buffer adducts are formed with a range of hydroxyl and amino function containing buffers including TES, BES, TRIS, BIS-TRIS, BIS-TRIS propane, Tricine, Bicine, HEPES and triethanol amine. It is recommended to use alternative buffers like MOPS, MES and CHES when working with G-type nerve agents especially at higher concentrations and over prolonged times.
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PMID:Stable adducts of nerve agents sarin, soman and cyclosarin with TRIS, TES and related buffer compounds--characterization by LC-ESI-MS/MS and NMR and implications for analytical chemistry. 2017 68