human
***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: The whole-body inflammatory response produced by cardiopulmonary bypass is an important cause of perioperative morbidity after cardiac operations . This inflammatory response produces reactive oxygen species and other cytotoxic substances , such as the cytokines . The generation of reactive oxygen species might deplete principal antioxidant micronutrients , that is , vitamins C and E and the carotenoids . Therefore , we have investigated the time course of the plasma concentrations of vitamins C and E and the carotenoids in 18 patients undergoing coronary bypass operations after r and omization for previous vitamin E supplementation ( 300 mg dl-alpha-acetyl-tocopherol 3 times daily for 4 weeks ) or placebo .  Supplementation with alpha-tocopherol doubled the lipid-st and ardized plasma vitamin E concentration to 63.7 + /- 14.5 mumol/L when compared with that of the control subjects ( 31.2 + /- 9.0 mumol/L ) before the operation . The plasma concentrations of vitamin C ( 36.0 + /- 19.0 mumol/L and 44.0 + /- 21.7 mumol/L , respectively ) and of the carotenoids were not statistically different between the two groups at baseline . The absolute plasma concentrations of both vitamin E and the carotenoids decreased during and after cardiopulmonary bypass , but after correction for hemodilution the plasma concentrations of vitamin E and the carotenoids showed no decrease . The vitamin E concentrations in the erythrocytes did not change either . In contrast , the plasma concentration of vitamin C decreased in all subjects within 24 hours after the operation by roughly 70 % . Correction for hemodilution still revealed a significant decrease in plasma vitamin C that persisted in most patients up to 2 weeks . In conclusion , the vitamin E and the carotenoid plasma concentrations are of no major concern during and after cardiac operations . In contrast , the serious depletion of vitamin C may deteriorate the defense against reactive oxygen species-induced injury during cardiac operations OBJECTIVES Our goal was to explore whether antioxidant vitamin C infusion is able to affect the microcirculation perfusion in patients undergoing elective percutaneous coronary intervention for stable angina . BACKGROUND Periprocedural myocardial injury in the setting of elective percutaneous coronary intervention is associated with increased risk of death , recurrent infa rct ion , and revascularization at follow-up . Despite excellent epicardial blood flow , impaired microcirculatory reperfusion may persist and increases the risk of vascular recurrences . Post-percutaneous coronary intervention induced-oxidative stress is one of the potential mechanisms accounting for impaired perfusion . METHODS Fifty-six patients were enrolled in a prospect i ve , single-center , r and omized study comparing 1 g vitamin C infusion ( 16.6 mg/min , over 1 h before percutaneous coronary intervention ) versus placebo . RESULTS At the baseline , Thrombolysis In Myocardial Infa rct ion ( TIMI ) myocardial perfusion grade < 2 was observed in 89 % and in 86 % of patients r and omized to the placebo or vitamin C infusion group , respectively ( p > 0.05 ) . After percutaneous coronary intervention , these percentages decreased in the placebo group ( 32 % ) and in greater measure in the vitamin C group ( 4 % , p < 0.01 ) . Complete microcirculatory reperfusion ( TIMI myocardial perfusion grade = 3 ) was achieved in 79 % of the vitamin C-treated group compared with 39 % of the placebo group ( p < 0.01 ) ; 8-hydroxy-2-deoxyguanosine ( p < 0.002 ) and 8-iso-prostagl and in F(2alpha ) ( p < 0.02 ) plasma levels significantly increased in the placebo group while they were significantly reduced in the vitamin C-treated group ( p < 0.0001 ) . TIMI myocardial perfusion grade changes from the baseline showed significant correlation with 8-hydroxy-2-deoxyguanosine ( p < 0.006 ) or 8-iso-prostagl and in F(2alpha ) ( p < 0.01 ) plasma levels changes . CONCLUSIONS In patients undergoing elective percutaneous coronary intervention , impaired microcirculatory reperfusion is improved by vitamin C infusion suggesting that oxidative stress is implicated in such a phenomenon BACKGROUND Atrial fibrillation occurs after approximately 25 % to 45 % of coronary artery bypass graft ( CABG ) surgeries . Oxidative stress and related electrophysiological remodeling has been proposed as a potential cause of this atrial fibrillation . Perioperative supplementation of the antioxidant ascorbic acid has been evaluated as a preventive agent . The current investigation was conducted to evaluate the efficacy of ascorbic acid in reducing atrial fibrillation  in CABG patients . METHODS A prospect i ve , r and omized , placebo-controlled , triple-blind , single-institution study was conducted in nonemergency CABG patients . Subjects were monitored for episodes of arrhythmia and other complications . RESULTS Eighty-nine treatment and 96 control subjects completed the study protocol . Demographics , comorbidities , and preoperative drugs were similar between groups . Surgical characteristics and postoperative medication use also were similar . The incidence of atrial fibrillation was 30.3 % in the treatment group and 30.2 % in the control group ( P = .985 ) . No difference was found in postoperative complications or mortality . CONCLUSIONS Our data indicate that supplementation of ascorbic acid in addition to routine postoperative care does not reduce atrial fibrillation after coronary artery bypass grafting Background : Prolonged intensive care unit ( ICU ) and hospital stay after cardiac surgery is vitally important and is influenced by both intraoperative and postoperative factors . Objectives : This r and omized clinical trial study was design ed to assess whether vitamin C supplementation could reduce the length of ICU and hospital stay in post-cardiac surgery patients . Patients and Methods : Two hundred and ninety patients scheduled for adult cardiac surgery including coronary , valve and congenital operations were r and omized into two groups : an intervention group , who received 2 g of vitamin C ( ascorbic acid ) intravenously , immediately before surgery in the operating theatre , followed by 1 g daily oral doses for the first 4 postoperative days ; and a placebo group , who received an equal number of identical tablets in the same shape and size . Results : Hospital length of stay was significantly different between the two groups ( 10.17 ± 4.63 days in the intervention group vs. 12 ± 4.51 days in the placebo group ; P = 0.01 ) , while there was no significant difference in the ICU stay between the groups ( 3.42 ± 1.06 days in intervention group vs. 3.43 ± 1.09 days in the placebo group ; P = 0.88 ) . There were significant differences in the intubation time and the drainage volume in the ICU and the first 24 postoperative hours between the two groups ( P for both = 0.003 ) . Conclusions : Vitamin C can decrease the length of hospital stay , drainage volume in the ICU and in the first 24 postoperative hours , intubation time and some complications in patients after cardiac surgery ; perhaps by decreasing inflammatory factors BACKGROUND Some evidence s have shown the role of antioxidant vitamins in preventing  atrial fibrillation ( AF ) after coronary artery bypass grafting ( CABG ) surgery . We sought to determine the effect of oral vitamin C on the incidence of postoperative AF in patients undergoing elective isolated on-pump CABG surgery . METHODS One-hundred patients who underwent isolated CABG surgery  were prospect ively assigned into two groups : Group 1 - 50 patients received 2 g of oral vitamin C before and 500 mg twice daily lasting for 5 days after surgery ; Group 2 - 50 patients as the control group did not receive any . All patients were continuously monitored after surgery in the intensive careunit ( ICU ) , and then Holter monitoring was implemented for 72 h. RESULTS The mean of patients ' age was 61.31 ± 6.42 years . Postoperative AF occurred in 16 and 4 patients in control and treatment groups , respectively ( 32 % vs. 8 % , p = 0.003 ) . The ICU stay was 1.79 ± 0.313 and 2.10 ± 0.61 days for vitamin C and control groups , respectively ( p = 0.002 ) . The hospital stay was significantly lower in vitamin C group compared with that of the control group ( 5.32 ± 0.59 vs. 5.74 ± 1.30 days , respectively , p = 0.041 ) . Baseline erythrocyte sedimentation rate ( OR 1.030 , 95 % CI 1.003 - 1.058 , p = 0.030 ) and taking vitamin C ( OR 8.068 , 95 % CI 1.783 - 36.517 , p = 0.007 ) were the independent predictors of postoperative AF . CONCLUSIONS Oral vitamin C can be safely used to decrease the incidence of postoperative AF in patients undergoing elective isolated on-pump CABG surgery HYPOTHESIS High-dose ascorbic acid ( vitamin C ) therapy ( 66 mg/kg per hour ) attenuates postburn lipid peroxidation , resuscitation fluid volume requirements , and edema generation in severely burned patients . STUDY DESIGN AND SETTING A prospect i ve , r and omized study at a university trauma and critical care center in Japan . SUBJECTS AND METHODS Thirty-seven patients with burns over more than 30 % of their total body surface area ( TBSA ) hospitalized within 2 hours after injury were r and omly divided into ascorbic acid and control groups . Fluid resuscitation was performed using Ringer lactate solution to maintain stable hemodynamic measurements and adequate urine output ( 0.5 - 1.0 ml/kg per hour ) . In the ascorbic acid group ( n = 19 ; mean burn size , 63 % + /- 26 % TBSA ; mean burn index , 57 + /- 26 ; inhalation injury , 15/ 19 ) , ascorbic acid was infused during the initial 24-hour study period . In the control group ( n = 18 ; mean burn size , 53 % + /- 17 % TBSA ; mean burn index , 47 + /- 13 ; inhalation injury , 12/18 ) , no ascorbic acid was infused . We compared hemodynamic and respiratory measurements , lipid peroxidation , and fluid balance for 96 hours after injury . Two-way analysis of variance and Tukey test were used to analyze the data . RESULTS Heart rate , mean arterial pressure , central venous pressure , arterial pH , base deficit , and urine outputs were equivalent in both groups . The 24-hour total fluid infusion volumes in the control and ascorbic acid groups were 5.5 + /- 3.1 and 3.0 + /- 1.7 mL/kg per percentage of burn area , respectively ( P<.01 ) . In the first 24 hours , the ascorbic acid group gained 9.2 % + /- 8.2 % of pretreatment weight ; controls , 17.8 % + /- 6.9 % . Burned tissue water content was 6.1 + /- 1.8 vs 2.6 + /- 1.7 mL/g of dry weight in the control and ascorbic acid groups , respectively ( P<.01 ) . Fluid retention in the second 24 hours was also significantly reduced in the ascorbic acid group . In the control group , the ratio of PaO2 to fraction of inspired oxygen at 18 , 24 , 36 , 48 , and 72 hours after injury was less than that of the ascorbic acid group ( P<.01 ) . The length of mechanical ventilation in the control and ascorbic acid groups was 21.3 + /- 15.6 and 12.1 + /- 8.8 days , respectively ( P<.05 ) . Serum malondialdehyde levels were lower in the ascorbic acid group at 18 , 24 , and 36 hours after injury ( P<.05 ) . CONCLUSIONS Adjuvant administration of high-dose ascorbic acid during the first 24 hours after thermal injury significantly reduces resuscitation fluid volume requirements , body weight gain , and wound edema . A reduction in the severity of respiratory dysfunction was also apparent in these patients Atrial fibrillation ( AF ) , the most common chronic arrhythmia , increases the risk of stroke and is an independent predictor of mortality . Available pharmacological treatments have limited efficacy . Once initiated , AF tends to self-perpetuate , owing in part to electrophysiological remodeling in the atria ; however , the fundamental mechanisms underlying this process are still unclear . We have recently demonstrated that chronic human AF is associated with increased atrial oxidative stress and peroxynitrite formation ; we have now tested the hypothesis that these events participate in both pacing-induced atrial electrophysiological remodeling and in the occurrence of AF following  cardiac surgery . In chronically instrumented dogs , we found that rapid ( 40 
    Output:
    
agent
Conclusions Our meta- analysis indicates that vitamin C may prevent post-operative atrial fibrillation in some countries outside of the USA , and it may also shorten the duration of hospital stay and ICU stay of cardiac surgery patients .
Vitamin C is an essential nutrient that is safe and inexpensive .
***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: The whole-body inflammatory response produced by cardiopulmonary bypass is an important cause of perioperative morbidity after cardiac operations . This inflammatory response produces reactive oxygen species and other cytotoxic substances , such as the cytokines . The generation of reactive oxygen species might deplete principal antioxidant micronutrients , that is , vitamins C and E and the carotenoids . Therefore , we have investigated the time course of the plasma concentrations of vitamins C and E and the carotenoids in 18 patients undergoing coronary bypass operations after r and omization for previous vitamin E supplementation ( 300 mg dl-alpha-acetyl-tocopherol 3 times daily for 4 weeks ) or placebo .  Supplementation with alpha-tocopherol doubled the lipid-st and ardized plasma vitamin E concentration to 63.7 + /- 14.5 mumol/L when compared with that of the control subjects ( 31.2 + /- 9.0 mumol/L ) before the operation . The plasma concentrations of vitamin C ( 36.0 + /- 19.0 mumol/L and 44.0 + /- 21.7 mumol/L , respectively ) and of the carotenoids were not statistically different between the two groups at baseline . The absolute plasma concentrations of both vitamin E and the carotenoids decreased during and after cardiopulmonary bypass , but after correction for hemodilution the plasma concentrations of vitamin E and the carotenoids showed no decrease . The vitamin E concentrations in the erythrocytes did not change either . In contrast , the plasma concentration of vitamin C decreased in all subjects within 24 hours after the operation by roughly 70 % . Correction for hemodilution still revealed a significant decrease in plasma vitamin C that persisted in most patients up to 2 weeks . In conclusion , the vitamin E and the carotenoid plasma concentrations are of no major concern during and after cardiac operations . In contrast , the serious depletion of vitamin C may deteriorate the defense against reactive oxygen species-induced injury during cardiac operations OBJECTIVES Our goal was to explore whether antioxidant vitamin C infusion is able to affect the microcirculation perfusion in patients undergoing elective percutaneous coronary intervention for stable angina . BACKGROUND Periprocedural myocardial injury in the setting of elective percutaneous coronary intervention is associated with increased risk of death , recurrent infa rct ion , and revascularization at follow-up . Despite excellent epicardial blood flow , impaired microcirculatory reperfusion may persist and increases the risk of vascular recurrences . Post-percutaneous coronary intervention induced-oxidative stress is one of the potential mechanisms accounting for impaired perfusion . METHODS Fifty-six patients were enrolled in a prospect i ve , single-center , r and omized study comparing 1 g vitamin C infusion ( 16.6 mg/min , over 1 h before percutaneous coronary intervention ) versus placebo . RESULTS At the baseline , Thrombolysis In Myocardial Infa rct ion ( TIMI ) myocardial perfusion grade < 2 was observed in 89 % and in 86 % of patients r and omized to the placebo or vitamin C infusion group , respectively ( p > 0.05 ) . After percutaneous coronary intervention , these percentages decreased in the placebo group ( 32 % ) and in greater measure in the vitamin C group ( 4 % , p < 0.01 ) . Complete microcirculatory reperfusion ( TIMI myocardial perfusion grade = 3 ) was achieved in 79 % of the vitamin C-treated group compared with 39 % of the placebo group ( p < 0.01 ) ; 8-hydroxy-2-deoxyguanosine ( p < 0.002 ) and 8-iso-prostagl and in F(2alpha ) ( p < 0.02 ) plasma levels significantly increased in the placebo group while they were significantly reduced in the vitamin C-treated group ( p < 0.0001 ) . TIMI myocardial perfusion grade changes from the baseline showed significant correlation with 8-hydroxy-2-deoxyguanosine ( p < 0.006 ) or 8-iso-prostagl and in F(2alpha ) ( p < 0.01 ) plasma levels changes . CONCLUSIONS In patients undergoing elective percutaneous coronary intervention , impaired microcirculatory reperfusion is improved by vitamin C infusion suggesting that oxidative stress is implicated in such a phenomenon BACKGROUND Atrial fibrillation occurs after approximately 25 % to 45 % of coronary artery bypass graft ( CABG ) surgeries . Oxidative stress and related electrophysiological remodeling has been proposed as a potential cause of this atrial fibrillation . Perioperative supplementation of the antioxidant ascorbic acid has been evaluated as a preventive agent . The current investigation was conducted to evaluate the efficacy of ascorbic acid in reducing atrial fibrillation  in CABG patients . METHODS A prospect i ve , r and omized , placebo-controlled , triple-blind , single-institution study was conducted in nonemergency CABG patients . Subjects were monitored for episodes of arrhythmia and other complications . RESULTS Eighty-nine treatment and 96 control subjects completed the study protocol . Demographics , comorbidities , and preoperative drugs were similar between groups . Surgical characteristics and postoperative medication use also were similar . The incidence of atrial fibrillation was 30.3 % in the treatment group and 30.2 % in the control group ( P = .985 ) . No difference was found in postoperative complications or mortality . CONCLUSIONS Our data indicate that supplementation of ascorbic acid in addition to routine postoperative care does not reduce atrial fibrillation after coronary artery bypass grafting Background : Prolonged intensive care unit ( ICU ) and hospital stay after cardiac surgery is vitally important and is influenced by both intraoperative and postoperative factors . Objectives : This r and omized clinical trial study was design ed to assess whether vitamin C supplementation could reduce the length of ICU and hospital stay in post-cardiac surgery patients . Patients and Methods : Two hundred and ninety patients scheduled for adult cardiac surgery including coronary , valve and congenital operations were r and omized into two groups : an intervention group , who received 2 g of vitamin C ( ascorbic acid ) intravenously , immediately before surgery in the operating theatre , followed by 1 g daily oral doses for the first 4 postoperative days ; and a placebo group , who received an equal number of identical tablets in the same shape and size . Results : Hospital length of stay was significantly different between the two groups ( 10.17 ± 4.63 days in the intervention group vs. 12 ± 4.51 days in the placebo group ; P = 0.01 ) , while there was no significant difference in the ICU stay between the groups ( 3.42 ± 1.06 days in intervention group vs. 3.43 ± 1.09 days in the placebo group ; P = 0.88 ) . There were significant differences in the intubation time and the drainage volume in the ICU and the first 24 postoperative hours between the two groups ( P for both = 0.003 ) . Conclusions : Vitamin C can decrease the length of hospital stay , drainage volume in the ICU and in the first 24 postoperative hours , intubation time and some complications in patients after cardiac surgery ; perhaps by decreasing inflammatory factors BACKGROUND Some evidence s have shown the role of antioxidant vitamins in preventing  atrial fibrillation ( AF ) after coronary artery bypass grafting ( CABG ) surgery . We sought to determine the effect of oral vitamin C on the incidence of postoperative AF in patients undergoing elective isolated on-pump CABG surgery . METHODS One-hundred patients who underwent isolated CABG surgery  were prospect ively assigned into two groups : Group 1 - 50 patients received 2 g of oral vitamin C before and 500 mg twice daily lasting for 5 days after surgery ; Group 2 - 50 patients as the control group did not receive any . All patients were continuously monitored after surgery in the intensive careunit ( ICU ) , and then Holter monitoring was implemented for 72 h. RESULTS The mean of patients ' age was 61.31 ± 6.42 years . Postoperative AF occurred in 16 and 4 patients in control and treatment groups , respectively ( 32 % vs. 8 % , p = 0.003 ) . The ICU stay was 1.79 ± 0.313 and 2.10 ± 0.61 days for vitamin C and control groups , respectively ( p = 0.002 ) . The hospital stay was significantly lower in vitamin C group compared with that of the control group ( 5.32 ± 0.59 vs. 5.74 ± 1.30 days , respectively , p = 0.041 ) . Baseline erythrocyte sedimentation rate ( OR 1.030 , 95 % CI 1.003 - 1.058 , p = 0.030 ) and taking vitamin C ( OR 8.068 , 95 % CI 1.783 - 36.517 , p = 0.007 ) were the independent predictors of postoperative AF . CONCLUSIONS Oral vitamin C can be safely used to decrease the incidence of postoperative AF in patients undergoing elective isolated on-pump CABG surgery HYPOTHESIS High-dose ascorbic acid ( vitamin C ) therapy ( 66 mg/kg per hour ) attenuates postburn lipid peroxidation , resuscitation fluid volume requirements , and edema generation in severely burned patients . STUDY DESIGN AND SETTING A prospect i ve , r and omized study at a university trauma and critical care center in Japan . SUBJECTS AND METHODS Thirty-seven patients with burns over more than 30 % of their total body surface area ( TBSA ) hospitalized within 2 hours after injury were r and omly divided into ascorbic acid and control groups . Fluid resuscitation was performed using Ringer lactate solution to maintain stable hemodynamic measurements and adequate urine output ( 0.5 - 1.0 ml/kg per hour ) . In the ascorbic acid group ( n = 19 ; mean burn size , 63 % + /- 26 % TBSA ; mean burn index , 57 + /- 26 ; inhalation injury , 15/ 19 ) , ascorbic acid was infused during the initial 24-hour study period . In the control group ( n = 18 ; mean burn size , 53 % + /- 17 % TBSA ; mean burn index , 47 + /- 13 ; inhalation injury , 12/18 ) , no ascorbic acid was infused . We compared hemodynamic and respiratory measurements , lipid peroxidation , and fluid balance for 96 hours after injury . Two-way analysis of variance and Tukey test were used to analyze the data . RESULTS Heart rate , mean arterial pressure , central venous pressure , arterial pH , base deficit , and urine outputs were equivalent in both groups . The 24-hour total fluid infusion volumes in the control and ascorbic acid groups were 5.5 + /- 3.1 and 3.0 + /- 1.7 mL/kg per percentage of burn area , respectively ( P<.01 ) . In the first 24 hours , the ascorbic acid group gained 9.2 % + /- 8.2 % of pretreatment weight ; controls , 17.8 % + /- 6.9 % . Burned tissue water content was 6.1 + /- 1.8 vs 2.6 + /- 1.7 mL/g of dry weight in the control and ascorbic acid groups , respectively ( P<.01 ) . Fluid retention in the second 24 hours was also significantly reduced in the ascorbic acid group . In the control group , the ratio of PaO2 to fraction of inspired oxygen at 18 , 24 , 36 , 48 , and 72 hours after injury was less than that of the ascorbic acid group ( P<.01 ) . The length of mechanical ventilation in the control and ascorbic acid groups was 21.3 + /- 15.6 and 12.1 + /- 8.8 days , respectively ( P<.05 ) . Serum malondialdehyde levels were lower in the ascorbic acid group at 18 , 24 , and 36 hours after injury ( P<.05 ) . CONCLUSIONS Adjuvant administration of high-dose ascorbic acid during the first 24 hours after thermal injury significantly reduces resuscitation fluid volume requirements , body weight gain , and wound edema . A reduction in the severity of respiratory dysfunction was also apparent in these patients Atrial fibrillation ( AF ) , the most common chronic arrhythmia , increases the risk of stroke and is an independent predictor of mortality . Available pharmacological treatments have limited efficacy . Once initiated , AF tends to self-perpetuate , owing in part to electrophysiological remodeling in the atria ; however , the fundamental mechanisms underlying this process are still unclear . We have recently demonstrated that chronic human AF is associated with increased atrial oxidative stress and peroxynitrite formation ; we have now tested the hypothesis that these events participate in both pacing-induced atrial electrophysiological remodeling and in the occurrence of AF following  cardiac surgery . In chronically instrumented dogs , we found that rapid ( 40 
    Output:
    