***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: Our objectives were to study the effect of a nitric oxide donor on uterine blood flow velocity waveforms and maternal heart rate and blood pressure during the first trimester of pregnancy . Eleven women were examined at 8 - 12 weeks ' gestation , prior to elective termination of pregnancy . Each woman was r and omly given a sublingual tablet containing 5 mg of isosorbide dinitrate or placebo , on two consecutive days . Measurements of maternal blood pressure , heart rate and Doppler flow velocity waveforms of the ascending branch of the main uterine artery were obtained before , and every 2 min ( for 20 min ) after taking the drug or placebo . Following administration of isosorbide dinitrate , the mean arterial blood pressure fell from a control value of 82.5 + /- 5.6 mmHg to a nadir of 73 + /- 4.1 mmHg at 16 min ( p < 0.0001 ) . The mean maternal heart rate increased from a control value of 80.9 + /- 2.8 beats/min to a peak of 90.4 + /- 4.6 beats/min at 10 min ( p < 0.001 ) . The mean resistance index in the uterine artery fell from a control value of 0.80 + /- 0.02 to a nadir of 0.73 + /- 0.03 at 10 min ( p < 0.0001 ) . Analysis of covariance was employed to compensate for the effect of heart rate on the resistance index . The drug had a significant effect on the resistance index in the uterine artery , independent of maternal heart rate . These results suggest that drugs such as isosorbide dinitrate may have a potential benefit under such conditions where the production of nitric oxide ( i.e. endothelium-derived relaxing factor ) is decreased Background . To investigate the effect of dietary intake of the NO‐donor l‐arginine on the diastolic blood pressure in women with pre‐eclampsia OBJECTIVE : To assess the benefit of l-arginine , the precursor to nitric oxide , on blood pressure and recovery of the glomerular lesion in preeclampsia . METHODS : Forty-five women with preeclampsia were r and omized to receive either l-arginine or placebo until day 10 postpartum . Primary outcome measures including mean arterial pressure , glomerular filtration rate , and proteinuria were assessed on the third and 10th days postpartum by inulin clearance and albumin-to-creatinine ratio .  Nitric oxide , cyclic guanosine 3′5′ monophosphate , endothelin-1 , and asymmetric-dimethyl-arginine and arginine levels were assayed before delivery and on the third and 10th days postpartum . Healthy gravid women provided control values . Assuming a st and ard deviation of 10 mm Hg , the study was powered to detect a 10-mm Hg difference in mean arterial pressure ( α .05 , β .20 ) between the study groups . RESULTS : No significant differences existed between the groups with preeclampsia before r and omization . Compared with the gravid control group , women with preeclampsia exhibited significantly increased serum levels of endothelin-1 , cyclic guanosine 3′5′ monophosphate , and asymmetric-dimethyl-arginine before delivery . Despite a significant increase in postpartum serum arginine levels due to treatment , no differences were found in the corresponding levels of nitric oxide , endothelin-1 , cyclic guanosine 3′5′ monophosphate , or asymmetric-dimethyl-arginine between the two groups with preeclampsia . Further , there were no significant differences in any of the primary outcome measures with both groups demonstrating similar levels in glomerular filtration rate and equivalent improvements in both blood pressure and proteinuria . CONCLUSION : Blood pressure and kidney function improve markedly in preeclampsia by the 10th day postpartum . Supplementation with l-arginine does not hasten this recovery . LEVEL OF EVIDENCE : Objective To determine the effects of the platelet-specific nitric oxide donor S-nitrosoglutathione on women with severe preeclampsia . Methods Ten women with severe preeclampsia or preeclampsia with severe fetal compromise at 21–33 weeks ' gestation each received a 60–90-minute intravenous infusion of 50–250 μg/minute of S-nitrosoglutathione . Each was hypertensive , despite conventional oral antihypertensive therapy in eight . Maternal blood pressure , heart rate , platelet activation , uterine artery , and fetal Doppler indices were measured during the infusion . Results A dose-dependent reduction in mean arterial pressure from 125 mmHg ( 95 % confidence interval [ CI ] 117–133 ) to 103.5 ( 95 % CI 97–111 ) ( P < .005 ) and an increase in pulse rate from 73.7 beats per minute ( 95 % CI 64.3–84.5 ) to 89.1 ( 95 % CI 81.2–97.8 ) ( P < .02 ) was observed during the infusion . Mean uterine artery resistance index fell from 0.76 ( 95 % CI 0.73–0.81 ) to 0.70 ( 95 % CI 0.65–0.75 ) ( P < .009 ) . Platelet activation measured by P-selectin expression was reduced from 3.02 % ( 95 % CI 2.09–4.36 ) to 1.22 % ( 95 % CI 0.94–1.58 ) ( P < .01 ) . Fetal Doppler indices ( umbilical artery , middle cerebral artery , and thoracic aorta ) showed no significant changes during the infusion . Conclusion S-nitrosoglutathione infusion reduced maternal mean arterial pressure , platelet activation , and uterine artery resistance without further compromising fetal Doppler indices . This study suggests that platelet-specific nitric oxide donors may prove beneficial in the management of severe preeclampsia OBJECTIVES [ corrected ] To investigate the effects of L-Arginine in treating asymmetric fetal growth restriction ( FGR ) . METHODS A total of 66 pregnant women whose fetuses were diagnosed with asymmetric fetal growth restriction were divided into two groups . Group 1 consisted of 36 women who were given routine therapy alone ; group 2 consisted of 30 women who were given L-Arginine and routine therapy ;  and the control group consisted of 30 more women with a normal pregnancy . RESULTS Before treatment , mean maternal serum levels of NO2-/NO3- were significantly lower in groups 1 and 2 than in the control group ( P<0.01 ) . After treatment , maternal serum levels of NO2-/NO3- were considerably higher in group 2 than in group 1 ( P<0.01 ) . Mean birth weight was significantly higher in group 2 than in group 1 ( P<0.05 ) , but still lower in group 2 than in the control group ( P<0.01 ) . CONCLUSIONS A deficiency in nitric oxide may play an important role in the development of asymmetric fetal growth restriction .  L-Arginine can be used to increase maternal NO2-/NO3- levels and newborn birth weight Objective : To evaluate the effects of L-arginine ( L-Arg ) supplementation on clinical outcomes and blood pressure ( BP ) changes in patients with gestational hypertension . Methods : Patients with gestational hypertension and proteinuria ( n = 28 , > 300mg/24 h ) and those without proteinuria ( n = 46 ) were r and omized in a double-blind design to receive either L-Arg ( 20g/500 mL intravenously daily , for 5 days followed by 4g/day orally for 2 weeks ) or placebo ( PL ) . The primary outcome variable was time from r and omization to delivery ( Latency ) . Automated BP readings were obtained every 2 hours , between 8.00 am and 8.00 pm daily , untill the sixth day after treatment . Results : At inclusion , gestational age and proportions of patients with proteinuria did not differ significantly between the PL and L-Arg group . Latency was significantly longer in the L-Arg group compared with the PL group ( 19.5 ± 16.9 vs. 31.7 ± 25.2 days ; p = 0.008 ) . Compared with baseline , both systolic and diastolic BP 6 days after treatment were significantly reduced in the L-Arg group but not in the PL group . The subgroup of patients without proteinuria r and omized to the group receiving L-Arg showed a trend to prolong pregnancy , to attenuate the evolution to PE , and to reduce the rate of low birth weight . Conclusions : The treatment with L-Arg seems promising in prolonging pregnancy and reducing blood pressure , particularly in patients with gestational hypertension and without proteinuria . This benefit should be confirmed in larger studies with the power to evaluate the effectiveness of L-Arg in preventing the development to preeclampsia OBJECTIVES Pre-eclampsia continues to be a major cause of maternal and perinatal mortality . A disorder of the nitric oxide system is implicated in the pathogenesis of this condition and preliminary studies have suggested a possible therapeutic role for nitric oxide donors in women with established pre-eclampsia . The aim of this study was to determine whether pre-eclampsia and its complications could be prevented by the long-term use of nitric oxide donors in a group of women identified to be at risk on the basis of abnormal uterine artery Doppler measurements . STUDY DESIGN We enrolled 40 healthy normotensive women at high risk of pre-eclampsia selected on the basis of abnormal uterine artery Doppler waveforms at 24 - 26 weeks of gestation . Women were r and omly allocated to receive transdermal glyceryl trinitrate 5 mg-patches or equivalent placebo patches in a double-blind r and omized study . The primary outcome measures were pre-eclampsia , fetal growth restriction , preterm delivery or small for gestational age/fetal growth restriction rates . Patches were worn daily from recruitment for 10 weeks or until delivery . RESULTS The primary outcomes were not significantly different in the placebo compared to the glyceryl trinitrate group . However , survival analysis of adverse events with gestation in both groups showed a significantly reduced risk of an adverse event in the glyceryl trinitrate group ( p = 0.004 ) , equating to a 73 % reduction in hazard . There was no difference in maternal systolic and diastolic blood pressure , mean uterine artery resistance index and fetal umbilical and middle cerebral artery pulsatility indices between the groups . CONCLUSIONS Low-dose prophylactic transdermal glyceryl trinitrate commenced late in the second trimester did not reduce the incidence of pre-eclampsia , preterm delivery or fetal growth restriction , but may increase the likelihood of a complication-free pregnancy .  Transdermal glyceryl trinitrate ( 5 mg/day ) did not affect maternal cardiovascular , uterine artery or fetal arterial Doppler parameters Estimation of the influence of oral supplementation with low dose of L-arginine on biophysical profile , foeto-placental circulation and neonatal outcome in preeclampsia . R and omized , placebo-controlled , double-blind , clinical trial . Oral therapy with 3 g of L-arginine daily or placebo as a supplement to st and ard therapy . Eighty-three preeclamptic women , r and omly assigned to the  L-arginine  ( n=42 ) or  placebo ( n=41 ) groups ; [ n=30 ( L-arginine ) and n=31 ( placebo ) ended the study , respectively ] . Foetal gain chances due to ultrasound biometry , biophysical profile , Doppler velocimetry of pulsatility indices of umbilical and middle cerebral arteries , cerebro-placental ratio , as well as differences in duration of pregnancy and clinical data of newborn .  L-arginine treatment transitory accelerated foetal gain and improved biophysical profile . Starting from 3rd week of therapy , the umbilical artery pulsatility indices values were significantly lower in L-arginine than in placebo group . Moreover , treatment with L-arginine caused significant increase of middle cerebral artery pulsatility indices and cerebro-placental ratio values . Latency was longer in L-arginine group . Neonates delivered in the L-arginine group revealed higher Apgar score . Supplementary treatment with oral L-arginine seems to be promising in improving foetal well-being and neonatal outcome as well as in prolonging pregnancy complicated with preeclampsia . However , these benefits require confirmation in more-powered , larger studies We compared the flow velocity waveforms of uterine and umbilical arteries in normotensive and pre-eclamptic patients at mid-gestation . In a r and omised controlled trial we tested the effects of isosorbide dinitrate ( ISDN , nitric oxide donor ) patch therapy on the flow velocity waveform of pre-eclamptic patients at mid-gestation . The resistance indices ( RI ) of human uterine and umbilical arteries were higher in pre-eclamptic patients compared to the normotensive patients . ISDN patch therapy significantly reduced the increased RI values of the umbilical artery in pre-eclamptic patients without any change in systemic blood pressures , but the RI values of the uterine artery were not significantly attenuated . The change of the umbilical artery might be due to the improvement of end-diastolic flow velocity . These results suggest that the f 
    Output:
    
There is insufficient evidence to draw reliable conclusions about whether nitric oxide donors and precursors prevent pre-eclampsia or its complications