***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: PURPOSE Ascorbic acid ( AA ) has been implicated as a risk factor for calcium oxalate stones due to its conversion to oxalate and potential acidifying properties . We evaluated the effect of AA consumption on urinary saturation of calcium oxalate ( CaOx ) and urinary pH. MATERIAL S AND METHODS A total of 12 normal subjects ( NS ) and 12 CaOx stone formers ( SF ) underwent 2 , 6-day phases of study while maintained on a controlled metabolic diet . In each phase subjects ingested 1 gm AA or an identical appearing placebo twice daily . On the last 2 days of each phase 2 , 24-hour urine collection s were analyzed for pH and stone risk factors , and blood specimens were su bmi tted for serum chemistry studies . RESULTS No difference in urinary pH was found between placebo and AA phases in NS ( 6.02 versus 6.02 ) and SF ( 6.0 versus 6.0 ) . However , urinary oxalate was statistically significantly higher in the AA versus placebo phase for NS ( 34.7 versus 28.5 mg , p = 0.008 ) and SF ( 41.0 versus 30.5 mg , p < 0.001 ) . Likewise , the CaOx relative saturation ratio was significantly higher in the AA versus placebo phase for both groups . CONCLUSIONS Ingestion of 2 gm AA daily results in no change in urinary pH but a moderate though statistically significant increase in urinary oxalate in NS ( 20 % ) and SF ( 33 % ) . Stone formers respond no differently to AA than normal subjects . We recommend limiting AA use to less than 2 gm daily in CaOx stone formers 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 BACKGROUND The pathogenesis of reflex sympathetic dystrophy ( RSD ) is not clear , nor is there a definitive treatment for this syndrome . The morbidity , costs in health care , and loss of work time justify the search for a means to prevent post-traumatic dystrophy . Although the role of toxic oxygen radicals has not yet been clarified , we investigated vitamin C ( ascorbic acid ) as a prophylactic antioxidant drug . METHODS 123 adults with 127 conservatively treated wrist fractures were r and omly allocated in a double-blind trial to take a capsule of 500 mg vitamin C or placebo daily for 50 days . Each participant 's sex , age , side of fracture , dominance , fracture type , dislocation , reduction , and complaints with the plaster cast were recorded , and they were clinical ly scored for RSD . The follow-up lasted 1 year . FINDINGS Eight patients were withdrawn after r and omisation . 52 patients with 54 fractures ( male 22 % , female 78 % ; mean age 57 years ) received vitamin C and 63 patients with 65 fractures ( male 20 % , female 80 % ; mean age 60 years ) received placebo .  RSD occurred in four ( 7 % ) wrists in the vitamin C group and 14 ( 22 % ) in the placebo group 15 % ( 95 % CI for differences 2 - 26 ) . Other significant prognostic variables for the occurrence of RSD were complaints while wearing the cast ( relative risk 0.17 [ 0.07 - 0.41 ] ) and fracture type ( 0.37 [ 0.16 - 0.89 ] ) . INTERPRETATION This prospect i ve , double-blind study shows that vitamin C was associated with a lower risk of RSD after wrist fractures . Our hypothesis is that this beneficial effect of prophylaxis would be useful in other forms of trauma Acute Reflex Sympathetic Dystrophy ( acute RSD ) was defined using a reproducible classification . Elevated temperature of the affected extremity ( “ calor ” ) , measured by the dorsal side of the observer 's h and and mentioned by the patient , pain ( “ dolor ” ) measured by the Visual Analogue Scale ( VAS ) , redness ( “ rubor ” ) , edema ( “ tumor ” ) and limited active range of motion ( “ functio laesa ” ) , all contributed to the classification system . Patients scoring 4 or 5 positive symptoms were considered to have acute RSD Diet plays an important role in the pathogenesis of kidney stones . Because the metabolism of many dietary factors , such as calcium , may change with age , the relation between diet and kidney stones may be different in older adults . Uncertainty also remains about the association between many dietary factors , such as vitamin C , magnesium , and animal protein , and the risk of kidney stone formation . To examine the association between dietary factors and the risk of incident , symptomatic kidney stones in men and to determine whether these associations vary with age , a prospect i ve cohort study was conducted of 45,619 men without a history of nephrolithiasis .  Self-administered food frequency question naires were used to assess diet every 4 yr . A total of 1473 incident symptomatic kidney stones  were documented during 477,700 person-years of follow-up . For men aged < 60 yr , the multivariate relative risk ( RR ) for stone formation in the highest quintile of dietary calcium as compared with the lowest quintile was 0.69 ( 95 % confidence interval [ CI ] , 0.56 to 0.87 ; P = 0.01 for trend ) . By contrast , there was no association between dietary calcium and stone formation in men aged 60 yr or older . The multivariate RR for men who consumed 1000 mg or greater of vitamin C per day compared with those who consumed less than the recommended dietary allowance of 90 mg/d was 1.41 ( 95 % CI , 1.11 to 1.80 ; P = 0.01 for trend ) . Other dietary factors showed the following multivariate RR among men in the highest quintile of intake compared with those in the lowest : magnesium , 0.71 ( 95 % CI , 0.56 to 0.89 ; P = 0.01 for trend ) ; potassium , 0.54 ( 95 % CI , 0.42 to 0.68 ; P < 0.001 for trend ) ; and fluid , 0.71 ( 95 % CI , 0.59 to 0.85 ; P < 0.001 for trend ) . Animal protein  was associated with risk only in men with a body mass index < 25 kg/m(2 ) ( RR , 1.38 ; 95 % CI , 1.05 to 1.81 ; P = 0.03 for trend ) . Sodium , phosphorus , sucrose , phytate , vitamin B(6 ) , vitamin D , and supplemental calcium were not independently associated with risk . In conclusion , the association between calcium intake and kidney stone formation varies with age . Magnesium intake decreases and total vitamin C intake seems to increase the risk of symptomatic nephrolithiasis . Because age and body size affect the relation between diet and kidney stones , dietary recommendations for stone prevention should be tailored to the individual patient Abstract The benefits of various minerals and vitamins on fracture healing have been demonstrated in animal models .  Vitamin C is an essential substance in fracture healing but has not been studied previously on an experimental basis . Sixteen rats were grouped r and omly into control and vitamin C-supplemented groups . The right tibias of all rats were fractured by digital manipulation . One group received single high dose of vitamin C intramuscularly . On the 5th , 10th , 15th , and 20th days , two rats from each group were killed and the tibias examined under light microscopy . It was seen that the vitamin C-supplemented group went through the stages of fracture healing faster compared with the control group OBJECTIVE To examine the incidence and predictors of complex regional pain syndrome type I ( CRPS I ) after fracture of the distal radius . DESIGN Prospect i ve study . SETTING University hospital . PARTICIPANTS A consecutive sample of patients ( N=90 ) with fracture of the distal radius treated by closed reduction and casting .  INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES Occurrence of CRPS I , occurrence of pain , wrist and h and range of motion , radiographic measures , Patient-Rated Wrist Evaluation , Hospital Anxiety and Depression Scale , and Medical Outcomes Study 36-Item Short-Form Health Survey at baseline and 1 , 3 , 6 , and 9 months follow-up . RESULTS CRPS I occurred in 29 patients ( 32.2 % ) with a mean delay ± SD of 21.7±23.7 days from cast removal . Univariate analyses found significant differences between patients with CRPS I and patients without CRPS I at baseline for sex ( P=.021 ) , socioeconomic level ( P=.023 ) , type of trauma ( P=.05 ) , pain at rest and activity ( P=.006 and P<.001 , respectively ) , wrist dorsiflexion and pronation ( P=.002 and P=.001 , respectively ) , finger flexion ( P=.047 ) , thumb opposition ( P=.002 ) , function of the h and ( P<.001 ) , and physical quality of life ( QOL ) ( P=.013 ) . Logistic regression showed that risk for CRPS I was higher in cases of women ( odds ratio [OR]=5.774 ; 95 % confidence interval [ CI ] , 1.391 - 23.966 ) , medium and low energy trauma patients ( OR=7.718 ; 95 % CI , 1.136 - 52.44 ) , patients with a Medical Outcomes Study 36-Item Short-Form Health Survey physical functioning score < 40 ( OR=4.931 ; 95 % CI , 1.428 - 17.025 ) , and patients with Patient-Rated Wrist Evaluation pain subscale score > 16 ( OR=12.192 ; 95 % CI , 4.484 - 43.478 ) . CONCLUSIONS CRPS I occurs frequently during the third and fourth week after cast removal , especially in women who report severe pain and impairment of physical QOL . Additional prospect i ve studies are required to verify these findings in comminuted 
    Output:
    
The number of causal/association criteria met was adequate to support the scientific premise of the effect of vitamin C in preventing CRPS after DRF .
Furthermore , vitamin C administration is of relatively low cost and has few complications unless administered in large doses .
Owing to sufficient epidemiological evidence availability , the American Academy of Orthopaedic Surgeons recommendation of vitamin C to prevent CRPS has practical merit .