***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: Since carnitine deficiency has been reported in some patients undergoing maintenance hemodialysis , we studied the effects of intravenous infusion of L-carnitine or placebo at the end of each dialysis treatment . The trial , which lasted seven months ( one month baseline , 6 months treatment ) was multicenter , double blind , placebo controlled , and r and omized . Eighty-two long-term hemodialysis patients , who were given either carnitine ( N = 38 ) or placebo ( N = 44 ) , completed this study . In each group , clinical and biochemical parameters during treatment were compared with baseline values . Intra-dialytic hypotension and muscle cramps were reduced only in the carnitine treated group , while improvement in post-dialysis asthenia was noticed in both carnitine and placebo groups . Maximal oxygen consumption , measured during a progressive work exercise test , improved significantly in the carnitine group ( 111 + /- 50 ml/min . P less than 0.03 ) and was unchanged in the placebo group . L-carnitine treatment was associated with a significant drop in pre-dialysis concentrations of serum urea nitrogen , creatinine and phosphorus ( means + /- SEM , 101 + /- 4.5 to 84 + /- 3.9 , 16.7 + /- 0.67 to 14.7 + /- 0.64 , and 6.4 + /- 0.3 to 5.5 + /- 0.4 mg/dl , respectively , P less than 0.004 ) . No significant changes in any of these variables were noticed in the placebo group . Mid-arm circumference and triceps skinfold thickness were measured in 11 carnitine and 13 placebo treated patients . Calculated mid-arm muscle area increased in the carnitine patients ( 41.37 + /- 2.68 to 45.6 + /- 2.82 cm2 , P = 0.05 ) and remained unchanged in the placebo patients . ( ABSTRACT TRUNCATED AT 250 WORDS It has been reported that treatment with L-carnitine at a daily dose of 3 g orally may cause a rise in platelet aggregation and serum triglyceride concentration in hemodialyzed patients . The present double-blind cross-over study has been performed to evaluate the influence of L-carnitine when compared with placebo on platelet aggregation and plasma concentrations of various factors involved in platelet activation . In addition , the concentration of triglycerides , cholesterol and HDL-cholesterol has been evaluated . 18 uremic patients on maintenance hemodialysis for at least 1 year were r and omly allocated either to a control group receiving placebo or to a group treated with L-carnitine . Statistical analysis performed by means of ANOVA did not show any significant change in the serum concentration of cholesterol , HDL-cholesterol and triglycerides . Furthermore , platelet aggregation tests ( performed with adenosine 5'-diphosphate , epinephrine , thrombin and collagen ) and plasma beta-thromboglobulin concentration did not show any statistically significant difference . In addition , the plasma concentration of several coagulation markers , such as factor VIIIc , antithrombin III , alpha 2-antiplasmin , and fibrinopeptide A , did not show any significant variation . The results suggest that under our experimental conditions L-carnitine neither increases the risk of thromboembolism nor alters the serum lipid content in uremic patients on chronic hemodialysis Hypertriglyceridemia is often present in chronically uremic patients treated with maintenance hemodialysis and has been considered a risk factor in the accelerated development of atheroma . Muscle carnitine content is low in hemodialyzed patients . This abnormality may help to explain the myopathy and cardiomyopathy often observed in these subjects . In addition , carnitine might play a role in the hypertriglyceridemia in renal failure . Carnitine , which is necessary for fatty acid oxidation , has been recently reported to lower serum triglycerides in patients with type IV hyperlipoproteinemia .  Carnitine was administered intravenously three times weekly at the end of hemodialysis in eight patients .  Carnitine was given in 0.5 g doses for 8 weeks and then in 1.0 g doses for 6 additional weeks . There was a significant decrease in serum triglycerides at the end of treatment . In contrast , serum lipids in eight hemodialysis patients receiving placebo  did not change significantly . Carnitine administration does not cause any side effect except some euphoria . These results suggest that carnitine may be effective in the treatment of hypertriglyceridemia in dialysis patients A group of 14 uremic patients on intermittent hemodialysis was admitted to a cross-over double-blind trial in order to evaluate serum and muscle carnitine levels before and after 60 days of L-carnitine oral ( 2 g/day ) treatment . The morphology of muscle fragments was studied by light and electron microscopy . Symptoms ( asthenia , cramps ) occurring during hemodialysis were also recorded . After L-carnitine treatment the blood and muscle levels of the metabolite increased simultaneously to reduced asthenia and cramps . Morphological examination of the muscle of 13 of 14 patients did not reveal any pre- or posttreatment pathological alterations . The presence of nemaline rods was morphologically diagnosed in only one case and was no longer observed at the second biopsy at 2 months of L-carnitine treatment Left ventricular function was non-invasively studied in 28 r and omly selected haemodialysis patients before and after administration of L-carnitine , 2 g i.v . three times per week or saline  in a double blind design ed study over a six-week period . Cardiac function variables showed no relationship to muscle ( vastus lateralis ) and plasma carnitine concentrations . No apparent deficiency in muscle carnitine was found , whereas total plasma carnitine was lower in female patients than in female controls , p less than 0.002 . The echocardiographic left ventricular end-diastolic diameter was initially increased in about one third and the ejection fraction was depressed in about one fifth of the patients . An increased A : H ratio was found in 15 % . Systolic time intervals were deranged in 30 % of the patients . After carnitine administration , marked increases of muscle and plasma carnitine levels were found , p less than 0.01 , but no effects were recorded in any of the cardiac tests . Muscle carnitine increased from 14.6 mmol/kg dry weight to a median of 23.7 mmol/kg . We found no support for the hypothesis that carnitine depletion is responsible for cardiac dysfunction in haemodialysis patients Previous studies have reported conflicting results of carnitine supplementation on plasma lipids in patients with chronic renal failure . We therefore performed a four center , double-blind placebo controlled trial to evaluate the effects of post-hemodialysis intravenous injection of L-carnitine in ESRD patients on maintenance hemodialysis . Thirty-eight patients received up to six months of L-carnitine infusions ( 20 mg/kg ) post-dialysis and 44 patients received placebo infusions .  In both groups of patients , baseline pre-dialysis plasma and red blood cell total carnitine levels were normal , but pre-dialysis plasma-free carnitine concentrations and free/total ratios were subnormal , and plasma acyl levels were elevated . Post-dialysis plasma free and total carnitine concentrations were also subnormal . Plasma and red blood cell total carnitine levels rose eightfold in carnitine recipients , but were unchanged from baseline in those receiving placebo . There were no significant changes observed in plasma triglycerides , HDL-cholesterol or other lipoprotein parameters in either the carnitine or placebo treated groups . We conclude that carnitine metabolism is altered in uremia . Furthermore , in a r and omly-selected hemodialysis population , L-carnitine injection at the dose of 20 mg/kg results in significant increases in blood ( and perhaps tissue ) carnitine levels , but this is not associated with any major effects on lipid profiles End-stage renal disease affects every aspect of a patient 's life , including perception of health and quality of life . It is likely that a hemodialysis patient 's perceptions of health-related quality of life directly influence compliance with medical , nursing , and nutritional prescriptions . Because L-carnitine supplementation is known to enhance muscle strength and energy in hemodialysis patients , we hypothesized that L-carnitine supplementation would enhance a hemodialysis patient 's perception of health-related quality of life . To test this hypothesis , 1 g L-carnitine or placebo was administered orally to 101 patients immediately before and after every hemodialysis treatment for 6 months . To assess health-related quality of life from the patient 's perspective , the Medical Outcomes Study Short Form 36 instrument was administered before the study and at 1.5-month intervals for the duration of the study . In addition , a 10-item question naire design ed to assess common intradialytic symptoms was administered at the end of each dialysis treatment . Other parameters analyzed included Kt/V(urea ) and level of nutrition . In the 6-month group , oral L-carnitine supplementation had an early positive effect on general health ( P < 0.02 ) and physical function ( P < 0.03 ) , but the perceived effect was not sustained throughout the 6 months of the study . In the 3-month group , L-carnitine supplementation improved vitality ( P < 0.02 ) and general health ( P < 0.01 ) . There was no association between Kt/V(urea ) and perceived health-related quality of life . Serum albumin concentration was directly correlated to how patients perceived the quality of their lives Carnitine supplementation in hemodialyzed patients was studied in a double-blinded , r and omized , controlled trial in order to eluci date the effect of intravenous carnitine on renal anemia in patients treated with recombinant human erythropoietin ( rHuEPO ) . Twenty stable hemodialysis ( HD ) patients received intravenous L-carnitine after each dialysis session in a dosage of 5 ( N = 15 ) and 25 ( N = 5 ) mg/kg , respectively , together with intravenous iron saccharate ( 20 mg/HD session ) for four months and without iron for a further four months . Twenty patients received placebo instead of carnitine with an identical iron regimen . After a run-in phase of six months with a stable rHuEPO requirement , the rHuEPO dose was adjusted monthly when necessary to maintain target hemoglobin levels . At study entry ( T0 ) , plasma and red blood cell carnitine levels did not correlate significantly with the rHuEPO requirement . However , plasma free and total carnitine levels showed a significant negative correlation with erythrocyte survival time at T0 . After four months of coadministration of intravenous iron and L-carnitine ( T4 ) , the  rHuEPO requirement decreased in 8 of 19 evaluable HD patients . In these responders , the weekly rHuEPO dose was decreased significantly by 36.9+/-23.3 % ( 183.7+/-131.7 at T0 vs. 126.6+/-127.9 U/kg/week at T4 , P < 0.001 ) . The  rHuEPO requirement , however , was unchanged when all carnitine-treated patients were compared between T0 and T4 ( T0 : 172.0+/-118.0 vs. T4 : 152.3+/-118.8 U/kg/week , P = 0.07 , NS ) , but the erythropoietin resistance index decreased significantly in this group ( T0 : 16.0+/-11.0 vs. T4 : 13.6+/-10.5 U/kg/week/g of hemoglobin , P < 0.02 ) . The erythrocyte survival time was measured in five HD patients treated with iron and carnitine at T0 and T4 . Two out of these patients were carnitine responders and showed an increase of erythrocyte survival time of 15 and 20 % , respectively . After the withdrawal of iron supplementation , the  rHuEPO requirement increased comparably in both L-carnitine- and placebo-treated patients during four more months . According to our data , L-carnitine , in addition to iron supplementation , may have an effect on erythropoietin resistance and erythrocyte survival time in HD patients . More than half of our patients , however , showed no benefit . Further studies to identify those HD patients who might have a benefit of carnitine supplementation , as well as studies concerning the optimal dosage , duration , and way of administration of carnitine supplementation and its mechanism of action , are required In a retrospective survey , 487 research projects approved by the Central Oxford Research Ethics Committee between 1984 and 1987 , were studied for evidence of publication bias . As of May , 1990 , 285 of the studies had been analysed by the investigators , and 52 % of these had been published . Studies with statistically significant results were more likely to be published than those finding no difference between the study groups ( adjusted odds ratio [ OR ] 2.32 ; 95 % confidence interval [ Cl ] 1.25 - 4.28 ) . Studies with significant results were also more likely to lead to a greater number of publications and presentations and to be published in journals with a high citation impact factor . An increased likelihood of publication was also associated with a high rating by the investigator of the importance of the study results , and with increasing sample size . The tendency towards publication 
    Output:
    
There was no effect of L-carnitine on triglycerides , total cholesterol , or any of its fractions .
In conclusion , L-carnitine can not be recommended for treating the dyslipidemia of maintenance hemodialysis patients .
By contrast , this review suggests a promising effect of L-carnitine on anemia management .