β-Glucuronidase

Fishman, William H.

doi:10.1016/b978-0-12-091302-2.50082-7

Cited by 55 publications

(16 citation statements)

References 28 publications

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“…To determine P-glucuronidase release, PMN were further treated with cytochalasin B (5 jig ml-') for 10 min prior to stimulation. After sedimentation of cells by centrifugation, any released ,3-glucuronidase activity was determined in the cell-free supernatant by measuring the generation of phenolphthalein from phenolphthalein-,B-(D)-glucuronide (Fishman, 1974).…”

Section: Methodsmentioning

confidence: 99%

Equipotent inhibition by R(−)−, S(+)‐ and racemic ibuprofen of human polymorphonuclear cell function in vitro.

Villanueva

Heckenberger

Strobach

et al. 1993

Brit J Clinical Pharma

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1. The effects of racemic (rac) ibuprofen and its S(+)‐ and R(−)− enantiomers on functions of human polymorphonuclear cells (PMN) and platelets were studied in vitro. 2. Rac‐ibuprofen inhibited PMN functions (O2‐ generation, beta‐glucuronidase release, LTB4 formation). Similar IC50 values (40‐100 microM) were obtained for the S(+)‐ and R(‐ )‐enantiomers. 3. All forms of ibuprofen inhibited cyclooxygenase‐ related platelet functions (aggregation, thromboxane formation). The S(+)‐enantiomer was about twice as active as the racemate while the R(‐ )‐enantiomer was at least 10‐fold less active. This demonstrates that the S(+) is the only cyclooxygenase inhibitory component of the racemate. 4. The concentrations of rac‐ibuprofen in PMN and platelets were similar to those in the incubation medium and represented equal concentrations of the enantiomers. This indicates that neither interconversion nor tissue accumulation of the compounds occurred. 5. These data indicate that antineutrophil effects of ibuprofen on human PMN are independent of cyclooxygenase inhibition. Therefore, R(−)− ibuprofen may be superior to the S(+)‐isomer for the treatment of PMN‐ dependent inflammatory diseases. However, effective free drug concentrations may not be obtained in vivo.

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Section: Methodsmentioning

confidence: 99%

Equipotent inhibition by R(−)−, S(+)‐ and racemic ibuprofen of human polymorphonuclear cell function in vitro.

Villanueva

Heckenberger

Strobach

et al. 1993

Brit J Clinical Pharma

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“…␤-Glucuronidase activity was assayed according to Fishman (1974). In short, 100 l of scraped H9c2(2-1) myotubes, with a protein concentration of 1 mg/ml, was incubated with 1 mM phenolphthalein-␤-glucuronide in a total volume of 250 l incubation medium (70 mM acetic acid at pH 5.0) for 60 min at 37 • C. Incubations without protein were used as a negative control, a homogenate from rat liver was used as a positive control.…”

Section: β-Glucuronidasementioning

confidence: 99%

A physiological role for glucuronidated thyroid hormones: Preferential uptake by H9c2(2-1) myotubes

Heide

Joosten

Dragt

et al. 2007

Molecular and Cellular Endocrinology

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Conjugation reactions are important pathways in the peripheral metabolism of thyroid hormones. Rat cardiac fibroblasts produce and secrete glucuronidated thyroxine (T4G) and 3,3 ,5-triiodothyronine (T3G). We here show that, compared to fibroblasts from other anatomical locations, the capacity of cardiofibroblasts to secrete T4G and T3G is highest. H9c2(2-1) myotubes, a model system for cardiomyocytes, take up T4G and T3G at a rate that is 10-15 times higher than that for the unconjugated thyroid hormones. T3 and T4, and their glucuronides, stimulate H9c2(2-1) myoblast-to-myotube differentiation. A substantial ␤-glucuronidase activity was measured in H9c2(2-1) myotubes, and this confers a deconjugating capacity to these cells, via which native thyroid hormones can be regenerated from glucuronidated precursors. This indicates that the stimulatory effects on myoblast differentiation are exerted by the native hormones. We suggest that glucuronidation represents a mechanism to uncouple local thyroid hormone action in the heart from that in other peripheral tissues and in the systemic circulation. This could represent a mechanism for the local fine-tuning of cardiac thyroid hormone action.

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“…The mice were sacrificed 4 h after the last application. Kidneys were excised and stored in liquid nitrogen until assayed for p-glucuronidase activity, which was determined by methods published previously [9]. In brief, each kidney was homogenized in 2 ml of 0.1 M acetate buffer, pH 4.5 in a glass-Teflon, PotterElvehjem-type homogenizer.…”

Section: Methodsmentioning

confidence: 99%

Androgenic Action of Progestins and Possible Synandrogenic Properties of Antiandrogens Used in Oral Contraceptives

Spona¹

1984

Gynecol Obstet Invest

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Relative binding affinities (RBA) for the androgen receptor were estimated for levonorgestrel, progesterone, dihydrotestosterone, cyproterone acetate, 17Α-propylmesterolone and 3-keto-desogestrel (13-ethinyl-ll-methylene-18,19-dinor-17Α-pregn-4-en-20-yn-17-ol-3-one) which is the biological active metabolite of desogestrel. Mouse kidney cytosol served as receptor source. In addition, stimulation of mouse kidney Β-glucuronidase by subcutaneous injection of various doses of these compounds was determined. RBA for the androgen receptor of 3-keto-desogestrel was significantly greater (p < 0.02) than that of levonorgestrel, and 3-keto-desogestrel was registered to enhance Β-glucuronidase activity more than levonorgestrel at the highest dose level (p < 0.005). Furthermore, cyproterone acetate in the presence of testosterone was found to exert synandrogenic action at the lower dose level but suppressed enzyme activity at the higher doses. On the other hand, 17Α-propylmesterolone which had RBA similar to the one noted for cyproterone acetate showed only synandrogenic properties at the dose levels tested. The data combine to suggest that biological activity of a compound cannot be accurately predicted by receptor assays. Desogestrel and levonorgestrel exhibit similar androgenic properties in this model system. These data correlate with clinical experience on oral contraceptives containing levonorgestrel and desogestrel, respectively, which do not differ from each other in their androgen-related side effects.

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β-Glucuronidase

Cited by 55 publications

References 28 publications

Equipotent inhibition by R(−)−, S(+)‐ and racemic ibuprofen of human polymorphonuclear cell function in vitro.

Equipotent inhibition by R(−)−, S(+)‐ and racemic ibuprofen of human polymorphonuclear cell function in vitro.

A physiological role for glucuronidated thyroid hormones: Preferential uptake by H9c2(2-1) myotubes

Androgenic Action of Progestins and Possible Synandrogenic Properties of Antiandrogens Used in Oral Contraceptives

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