***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: We studied the influence of captopril , atenolol , and verapamil on serum and intraerythrocyte concentrations of magnesium and zinc in 30 normotensive control subjects ( 12 men and 18 women , aged 30 to 65 years , mean + /- SD 45.76 + /- 12.15 years ) and 30 patients with untreated mild or moderate essential hypertension ( 14 men and 16 women , aged 30 to 65 years , mean + /- SD 49.50 + /- 13.58 years ) . Ten each of the hypertensive patients were treated with captopril , atenolol , or verapamil . Physical examination and biochemical analyses ( serum Mg and Zn ) were done in all participants at baseline , and in patients after 3 and 6 months of treatment . The results were compared according to a nested design with Neumann-Keuls test . We found no significant differences between controls and patients in serum and intraerythrocyte concentrations of Zn at the start of the study , although there was a significant decrease in serum Zn in patients after 3 ( P < .01 ) and 6 months ( P < .001 ) of treatment , regardless of the drug used . This decrease was thought to be attributable to the zincuric effect of captopril or to dietary measures , or both . Intraerythrocyte Zn was not significantly affected by antihypertensive treatment . Serum and intraerythrocyte concentrations of Mg were significantly lower ( P < .001 ) in hypertensive than in normotensive subjects , and serum Mg in patients treated with verapamil was significantly lower ( P < .05 ) than after treatment with captopril or atenolol .  Serum Mg concentration was related directly with serum concentrations of high density lipoprotein cholesterol ( r = 0.4043 , P < .05 ) . We conclude that supplementation with Mg may benefit patients with hypertension Urinary zinc excretion was studied in a r and omized trial in 9 patients during treatment with bendroflumethiazide , chlorthalidone and hydrochlorothiazide and in another 9 patients during treatment with bumetanide , furosemide and triamterene .  During treatment with the thiazides , the zinc concentration rose by 30 % and the total amount of zinc excretion increased by 60 % . In contrast , during treatment with the loop-diuretics , urine zinc concentration diminished and the total amount of zinc excretion increased much less than during therapy with the thiazides . With respect to the importance of zinc as an essential element in human metabolism and the frequency of diuretic treatment , the observed increased urinary losses of zinc deserve further attention Background Free oxygen radicals and insufficiency of antioxidant enzymes have been implicated in the pathogenesis of hypertension disease ( HD ) . Trace elements function as a co-factor in antioxidant enzymes . The antioxidant system and trace elements have been investigated in many different studies including HD , but these subjects have not been investigated as a whole in these patients . Objective The aim of the present study was to investigate the antioxidative system and trace elements in hypertensive patients given different antihypertensive therapy .  Methods We examined  malondialdehyde and superoxide dismutase activities together with copper and zinc levels in plasma of 102 patients with HD and in 51 healthy controls . Results It was found that in patients with HD , plasma malondialdehyde was significantly higher than those of controls , while plasma superoxide dismutase activities were significantly lower in patients with HD . Plasma zinc levels were significantly higher than those of controls and plasma copper levels were significantly lower in patients with HD . Plasma lipid levels and oxidative state were analyzed in five different treatment groups given antihypertensive drug therapy before and after a 3-month treatment period . Conclusions In conclusion , our clinical study shows that angiotensin-converting enzyme inhibitors and angiotensin receptor blockers have notable effects on oxidative stress , and are an essential step in managing essential hypertension by the way of improvement of endothelial dysfunction . Although it has been shown that calcium channel blockers , beta blockers and alpha receptor blockers have antioxidant effects in in vitro conditions , we did not demonstrate these effects in our clinical study This study was design ed to test the hypothesis that hydrochlorothiazide a diuretic used to treat hypertension depletes body zinc and thereby cause sexual dysfunction . Serum zinc and sexual dysfunction were measured in 39 middle aged hypertensive men who had been taking hydrochlorothiazide in average daily doses of between 25 and 50 mg daily for at least six months , and a control group of 27 unmedicated middle aged normotensive men . The medicated group had a higher incidence of  sexual dysfunction  ( 56 pc ) as compared to 11 pc in the control group . The use of hydrochlorothiazide did affect serum zinc levels significantly in 20 patients . Sexual dysfunction occurred more often in older and overweight patients ( p < 0.004 ) . Three of the normotensive men experienced sexual dysfunction probably related to old age . Twenty two of the 39 on hydrochlorothiazide and experiencing sexual dysfunction  were divided into two groups of 11 patients . Bloods were taken from the 27 normotensive and 22 hypertensive men receiving hydrochlorothiazide for the analyses of zinc . Subsequently one group of the patients were supplemented with zinc 500 mg daily for 30 days while the other group was supplemented with magnesium chloride 1 g daily for 30 days . The normotensive men were not treated . After 30 days , bloods were again taken from the three groups of analyses for zinc and magnesium . Serum zinc was significantly decreased ( p < 0.05 ) by hydrochlorothiazide and a non significant decrease in serum magnesium ( p = ns ) was observed . After supplementation with zinc , the serum zinc levels returned to normal only in eight patients . There was improvement in the symptoms of sexual dysfunction in five patients . Two patients gained weight . Hydrochlorothiazide decreased serum zinc levels ( p < 0.05 ) and was unchanged with magnesium supplementation but the serum magnesium returned to normal values . Improvement of symptoms of sexual dysfunction was positive in one patient . This study shows that low serum zinc levels may be associated with sexual dysfunction but the definitive role of zinc in the pathogenesis of sexual dysfunction will remain controversial 
    Output:
    
CONCLUSION The available evidence suggests that use of ACE inhibitors and angiotensin 2 receptor antagonists or thiazide diuretics have the potential to reduce zinc levels in hypertensive patients .