[An important variability factor in determination of urinary activity of N-acetyl-beta-D-glucosaminidase: contamination of urine with semen]. / A proposito di un importante fattore di variabilità nella determinazione dell'attività urinaria della N-acetil-beta-D- glucosaminidasi: la contaminazione delle urine con liquido seminale.

BACKGROUND: Urinary N-acetyl-beta-D-glucosaminidase (U-NAG) and its isoenzyme B (U-NAG-B) have been demonstrated useful and early markers of renal damage, although they are present in many other tissues and organs. OBJECTIVES: To evaluate semen contamination of the urine and its role in variability of U-NAG. METHODS: To assess control group values beta2-microglobulin, retinol-binding protein and U-NAG were measured in the urine of 30 healthy, non-smoking and non metal-exposed adults (19 females and 11 males). RESULTS: In four urine samples U-NAG was higher than the method reference value (5 U/g creatinine), without increases in other functional markers. Microscope examination revealed the presence of sperm in these samples. U-NAG variability decreased after the exclusion of these four values. The role of contamination was confirmed by adding semen to urine: when semen to urine ratio was 1:1000, enzyme activity was more than twice the basal level. CONCLUSIONS: U-NAG variability is strongly increased by contamination with semen, where enzyme concentration (especially NAG-B) is very high. Increased excretion of U-NAG and of its iso-form (U-NAG-B) in males, not correlated with other renal alterations or with exposure to heavy metals or other renal toxic substances, should be carefully evaluated and microscopic observation is advisable to detect the presence of sperm in urine.

Automated analysis of urinary catecholamines by high-performance liquid chromatography and on-line sample pretreatment.

A simple and automated solid-phase extraction for the selective and quantitative HPLC analysis of free catecholamines in urine is described. The urinary catecholamines react with diphenylboric acid, giving a complex at pH 8.5 which is strongly retained on a PLRP-S cartridge; elution is accomplished with the same mobile phase used for HPLC analysis. Separation is performed by ion-pair reversed-phase HPLC, with sodium heptanesulphate as counter-ion, and a totally end-capped C18 analytical column. Quantitation is achieved with an electrochemical detector. A Spark Holland Prospekt system controls the on-line solid-phase extraction, preconcentration and direct elution to the LC column. Chromatography run-time is 10 min and the total time to process one urine sample is ca. 12 min.

Platelet activation by emotional stress in patients with coronary artery disease.

We studied the effects of experimentally induced emotional stress (mental arithmetic) on different hemodynamic parameters, catecholamine levels, and serum and platelet function tests in 25 postinfarction patients and in 10 apparently healthy, age-matched control subjects. Mental stress (10 minutes) induced significant increments in heart rate, systolic blood pressure, diastolic blood pressure, double product, and cardiac output, indicating a sympatho-adrenal stimulation that was confirmed by a significant increase in serum epinephrine and norepinephrine levels. All of the effects disappeared at minute 10 of recovery. Concomitantly, the test produced a significant increase in platelet aggregation (induced by 3 microM ADP or 1 microgram/ml collagen), the formation of circulating platelet aggregates, and an increase in thromboxane B2 levels in plasma and serum. These effects were also rapidly reversible. Similar activation of hemodynamic parameters and a similar but less evident increase in platelet function by emotional stress were observed in control subjects. A possible artifact due to factitious platelet activation by catheter sampling was excluded with experiments in which a 40-minute rest was introduced after the baseline period and before mental stress; platelet activation did not occur during baseline or rest periods, only after emotional stress. Furthermore, the antiplatelet drug dipyridamole reduced the stress-induced formation of platelet aggregates in postinfarction patients. These results demonstrate the existence of a direct link between emotional stress and platelet function and offer an explanation of one of the mechanisms through which mental stress may be involved in the development of coronary artery disease.