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We determined the enzymic activity of beta-glucuronidase preparations from bovine liver, Helix pomatia, and Escherischia coli with steroid glucuronides and nonsteroid glucuronides as substrates. We also studied the effect of Na2SO4 on the enzymic hydrolysis of several substrates with the three preparations of beta-glucuronidase. Na2SO4 increases the rate of hydrolysis of all substrates with beta-glucuronidase from bovine liver. Hydrolysis of a steroid glucoronide with beta-glucuronidase from Helix pomatia and E. coli is inhibited by Na2SO4. None of the three enzyme preparations gives complete hydrolysis of urinary steroid conjugates, because urine contains inhibitors, which can be removed by absorption chromatography of the urine on a column of neutral polystyrene resin Amberlite XAD-2. But when Amberlite XAD-2 is not used, hydrolysis of urinary glucuronides of androsterone, etiocholanolone, pregnanediol, estriol, and 17-hydroxycorticosteroids proves that, given an incubation time of 24 h, the beta-glucuronidase preparation from bovine liver, in the presence of Na2SO4, is suited for determining all of the above steroids except esriol; the preparation from Helix pomatia is good for determining estriol and 17-hydroxycorticosteroids; the preparation from E. coli is good for determining androsterone, 17-hydroxycorticosteroids, and especially estriol, the glucuronide, of which is maximally hydrolyzed in 2 h.

Plasma aldosterone, cortisol, sodium (Na), potassium (K), calcium (Ca), magnesium (Mg) äs well äs urine and sweat Na, K, Ca and Mg concentrations were measured in nine male healthy persons during an one hour ergometer exercise before and after a fourteen day magnesium aspartate (Mg) Supplementation. The usual aldosterone and cortisol increase during exercise was not observed and cortisol concentration was significantly lowef after Mg Supplementation. Na and K in plasma increased during the exercise; these changes were not affected by Mg. The Mg concentration was elevated in plasma and erythrocytes after Mg Supplementation. During the ergometer course plasma Mg was unchanged but decreased significantly in the red blood cells. Mg and K concentration in sweat decreased during the exercise. No influence of Mg on urinary electrolyte excretion was observed. Aldosteron-, Cortisol" und Elektrolytkonzentrationen im Plasma bei körperlicher Belastung unter Magnesium-SubstitutionZusammenfassung: Die Konzentrationen von Cortisol, Aldosteron, Natrium (Na), Kalium (K), Calcium (Ca) und Magnesium (Mg) im Plasma sowie die Konzentrationen von Na, K, Ca und Mg im Urin und Schweiß wurden bei neun männlichen, gesunden Personen vor und nach einer 14tägigen Substitution mit Magnesium-Aspartat (Mg) während einer einstündigen Ergometerbelastung gemessen. Der üblicherweise während einer körperlichen Belastung gefundene Anstieg des Aldosterons und Cortisols im Plasma wurde bei den mit Magnesium substituierten Personen nicht gefunden. Die Cortisol-Konzentration im Plasma war nach der Mg-Substitution signifikant niedriger. Na und K im Plasma stiegen während der Belastung unabhängig von der Mg-Substitution an. Die Mg-Konzentf ation im Plasma und in den Erythrocyten stieg unter der Mg-Substitutron an. Während der Ergometerbelastung änderte sich die Mg-Konzentration im Plasma nicht, während sie in den roten Blützellen signifikant abfiel. Die Konzentrationen von Mg und K im Schweiß sanken während der Belastung. Ein Einfluß der Mg-Substitütion auf die Elektrolytausscheidung im Urin wurde nicht beobachtet. *) This paper will be part of the doctoral thesis of O. Happel.ing exercise (6).

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In order to clarify the role of 1, 25-dihydroxyvitamin-D [1, 25-(OH)₂-D] in calcium stone formation, correlations between l,25-(OH)₂-D serum levels and levels of calcium, phosphate and uric acid (UA) in serum or urine and between the l,25-(OH)₂-D serum level and age were analyzed in Ill formers of urinary stones (57 Ca stones) and in 44 controls. Furthermore, 1,25-(OH)₂-D serum levels as well as levels of Ca, phosphate and UA in serum and urine from formers of different urinary stones and controls were compared. 1,25-(OH)₂-D serum levels were determined by a radio-receptor assay based on a calf thymus receptor. l,25-(OH)₂-D serum levels correlated positiviely with urinary UA excretion in formers of Ca stones and with urinary Ca excretion in formers of Ca stones and controls. In formers of Ca stones urinary Ca excretion was higher and serum phosphate was lower than in controls. 1,25-(OH)₂-D serum levels did not differ. l,25-(OH)₂-D serum levels decreased with increasing age in controls, but not in stone formers. Our results show that urinary UA and 1,25-(OH)₂-D in serum co-influence Ca stone formation, and they suggest that there is an increased sensitivity to l,25-(OH)₂-D in formers of Ca stones.