***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 examined the effects of citric acid and l-carnitine administration on  physical fatigue .  In a double-blind , placebo-controlled , 3-way crossover study , 18 healthy volunteers were r and omized to oral citric acid ( 2,700 mg/day ) , l-carnitine ( 1,000 mg/day ) , or placebo for 8 days . The fatigue-inducing physical task consisted of workload trials on a cycle ergometer at fixed workloads for 2 h on 2 occasions . Before the physical load , salivary chromogranin A , measured as a physiological stress marker , was lower in the group given citric acid than in the group given placebo . Also , after the physical load , the subjective feeling of fatigue assessed with a visual analogue scale was lower in the citric acid group than in the placebo group . In contrast , l-carnitine had no effect on chromogranin A or subjective fatigue . These results suggest that citric acid reduces physiological stress and attenuates physical fatigue , whereas l-carnitine does not Background The purpose of this study was to examine the effect of acute and prolonged ( 4-weeks ) ingestion of a supplement design ed to improve reaction time and subjective measures of alertness , energy , fatigue , and focus compared to placebo . Methods Nineteen physically-active subjects ( 17 men and 2 women ) were r and omly assigned to a group that either consumed a supplement ( 21.1 ± 0.6 years ; body mass : 80.6 ± 9.4 kg ) or placebo ( 21.3 ± 0.8 years ; body mass : 83.4 ± 18.5 kg ) . During the initial testing session ( T1 ) , subjects were provided 1.5 g of the supplement ( CRAM ; α-glycerophosphocholine , choline bitartrate , phosphatidylserine , vitamins B3 , B6 , and B12 , folic acid , L-tyrosine , anhydrous caffeine , acetyl-L-carnitine , and naringin ) or a placebo ( PL ) , and rested quietly for 10-minutes before completing a question naire on subjective feelings of energy , fatigue , alertness and focus ( PRE ) . Subjects then performed a 4-minute quickness and reaction test followed by a 10-min bout of exhaustive exercise . The question naire and reaction testing sequence was then repeated ( POST ) . Subjects reported back to the lab ( T2 ) following 4-weeks of supplementation and repeated the testing sequence . Results Reaction time significantly declined ( p = 0.050 ) between PRE and POST at T1 in subjects consuming PL , while subjects under CRAM supplementation were able to maintain ( p = 0.114 ) their performance . Significant performance declines were seen in both groups from PRE to POST at T2 . Elevations in fatigue were seen for CRAM at both T1 and T2 ( p = 0.001 and p = 0.000 , respectively ) , but only at T2 for PL ( p = 0.029 ) . Subjects in CRAM maintained focus between PRE and POST during both T1 and T2 trials ( p = 0.152 and p = 0.082 , respectively ) , whereas significant declines in focus were observed between PRE and POST in PL at both trials ( p = 0.037 and p = 0.014 , respectively ) . No difference in alertness was seen at T1 between PRE and POST for CRAM ( p = 0.083 ) , but a significant decline was recorded at T2 ( p = 0.005 ) . Alertness was significantly lower at POST at both T1 and T2 for PL ( p = 0.040 and p = 0.33 , respectively ) . No differences in any of these subjective measures were seen between the groups at any time point . Conclusion Results indicate that acute ingestion of CRAM can maintain reaction time , and subjective feelings of focus and alertness to both visual and auditory stimuli in healthy college students following exhaustive exercise . However , some habituation may occur following 4-weeks of supplementation BACKGROUND Centenarians are characterized by weakness , decreasing mental health , impaired mobility , and poor endurance . L-Carnitine is an important contributor to cellular energy metabolism . OBJECTIVE This study evaluated the efficacy of L-carnitine on physical and mental fatigue and on cognitive functions of centenarians . DESIGN This was a placebo-controlled , r and omized , double-blind , 2-phase study . Sixty-six centenarians with onset of fatigue after even slight physical activity were recruited to the study . The 2 groups received either 2 g levocarnitine once daily ( n = 32 ) or placebo ( n = 34 ) . Efficacy measures included changes in total fat mass , total muscle mass , serum triacylglycerol , total cholesterol , HDL cholesterol , LDL cholesterol , Mini-Mental State Examination ( MMSE ) , Activities of Daily Living , and a 6-min walking corridor test . RESULTS At the end of the study period , the levocarnitine-treated centenarians , compared with the placebo group , showed significant improvements in the following markers : total fat mass ( -1.80 compared with 0.6 kg ; P < 0.01 ) , total muscle mass ( 3.80 compared with 0.8 kg ; P < 0.01 ) , plasma concentrations of total carnitine ( 12.60 compared with -1.70 mumol ; P < 0.05 ) , plasma long-chain acylcarnitine ( 1.50 compared with -0.1 micromol ; P < 0.001 ) , and plasma short-chain acylcarnitine ( 6.0 compared with -1.50 micromol ; P < 0.001 ) . Significant differences were also found in physical fatigue ( -4.10 compared with -1.10 ; P < 0.01 ) , mental fatigue ( -2.70 compared with 0.30 ; P < 0.001 ) , fatigue severity ( -23.60 compared with 1.90 ; P < 0.001 ) , and MMSE ( 4.1 compared with 0.6 ; P < 0.001 ) . CONCLUSIONS Our study indicates that oral administration of levocarnitine produces a reduction of total fat mass , increases total muscular mass , and facilitates an increased capacity for physical and cognitive activity by reducing fatigue and improving cognitive functions Objective : To determine the efficacy of acetyl-l-carnitine ( ALCAR ) on the rate of decline in early-onset AD patients . Methods : A 1-year , multicenter , double-blind , placebo-controlled , r and omized trial was conducted . Subjects were 45 to 65 years old , with a diagnosis of probable AD according to National Institute of Neurological Communicative Disorders – Alzheimer ’s Disease and Related Disorders Association criteria and had a Mini-Mental State Examination ( MMSE ) score between 12 and 26 . They were treated with ALCAR ( 1 g tid ) or placebo . Primary outcome measures were the Alzheimer ’s Disease Assessment Scale – Cognitive Component and the Clinical Dementia Rating Scale . Secondary measures included the ADAS Non-Cognitive Subscale , the MMSE , an Activities of Daily Living Scale ( ADL ) , and a Clinician-Based Impression of Change ( CIBIC ) . Results : Two-hundred twenty-nine patients were enrolled and r and omized to drug treatment , with 117 taking placebo  and 112 taking ALCAR . There were no significant differences between the two groups at baseline . For the primary outcome measures , there were no significant differences between the treatment groups on the change from baseline to endpoint in the intent-to-treat analysis . In the completer sample only , there was less deterioration in the MMSE for the ALCAR-treated subjects . There was no difference in rate of decline on the CIBIC and the ADL scale . There were no significant differences in the incidence of adverse events by treatment arm . Conclusion : Overall , in a prospect ively performed study in young-onset AD patients , ALCAR failed to slow decline . Less decline was seen on the MMSE in the completer sample only , with the difference being mediated by reducing decline in attention . A combination of ALCAR and a cholinesterase inhibitor should be tested for additivity A single-blind clinical trial was carried out on 481 subjects enrolled in 44 geriatric and neurologic units following a strict selection criteria : age , Mini Mental State Examination ( MMSE ) Global Deterioration Scale and Geriatric Depression Scale ( GDS ) . After the initial screening and enrollment , the trial was run for 150 days in four phases : phase T0 ( placebo treatment for 30 days ) , phases T1 and T2 ( L-acetylcarnitine ( LAC ) 1500 mg/day for 90 days ) , phase T3 ( further 30 days of placebo treatment ) . Drug efficacy was evaluated according to changes occurring from the beginning to the end of the tests which evaluate either whole and specific cognitive performances , or emotional-affective and relational behaviour . The outcome of phase T3 enabled the authors to estimate the possible favourable effects persisting after termination of L-acetylcarnitine therapy . The cognitive sphere evaluated by MMSE showed a significant increase in the total score at the end of LAC treatment ( p < 0.0001 ) . The R and t Memory Test also revealed that LAC treatment improved the items tested : the total score and the memory index increased significantly and the favourable effect persisted after LAC was discontinued . The emotional-affective area showed a significant improvement in the total score of the GDS after LAC therapy , and the positive results were confirmed by the Hamilton Rating Scale ( p < 0.0001 ) . The behavioural-relational aspects evaluated by the Family Stress Scale showed a significant decrease in the total score after treatment ( p < 0.0004 ) ; the same trend was observed in the scores for instability and negative feeling . No significant adverse drug reaction occurred during the trial . In conclusion , the statistical analysis of the data from this single-blind , multicentre trial of mild mental impairment in the elderly showed a significant improvement of several performances during and after LAC treatment . Other reports indicate that this drug may be effective in the treatment of dementia Twelve students with in apparent good health and fasting since the previous evening ingested 2 g of L-carnitine on one day and a placebo on another day in a single-blind trial . Six blood sample s were taken during the 24 h following the ingestion . Their blood carnitine levels increased ( the free form by 81 % , and the total by 57 % ) to a maximum at about 3.5 h and then slowly decreased . Twenty-four hours after ingestion , blood carnitine concentrations had still not returned to their initial levels . In the time interval where the decay curve approximated a single exponential , the half-life of the carnitine appeared to be of the order of 15 h. During the 24 h after the administration of the 2 g of L-carnitine , 7 % + /- 1 % of it was eliminated in the urine . This work suggest that the daily administration during a long period , of 2 g of L-carnitine guarantee in a healthy subject blood carnitine concentrations superior to the normal levels . Its remains to determine if the dose is sufficient in the case where L-carnitine is given to ameliorate a primary or secondary lack of carnitine , or to lower a high level of lipids in blood Abstract Objectives : To determine the efficacy of L-carnitine in reducing hyperammonaemia and improving neuropsychological performance in patients with hepatic cirrhosis and sub clinical hepatic encephalopathy ( SHE ) . Design : R and omised , parallel group , controlled trial . Patients and Methods : The study enrolled 31 patients with hepatic cirrhosis result ing from hepatitis C and /or hepatitis B , alcohol abuse and other causes . Patients r and omised to active treatment , received oral L-carnitine 6 g/day in two divided doses for 4 weeks . Diagnosis of SHE was based on psychometric tests ( subtests of the Wechsler Adult Intelligence Scale-Revised and the Halstead-Reitan Neuropsychological Test Battery ) carried out at beginning and end of study . Serum ammonia levels were measured before treatment and weekly thereafter . Results : A total of 27 patients completed the study . Sixteen patients received L-carnitine and 11 served as controls ( no treatment ) . L-carnitine caused rapid and significant reductions in ammonia levels , sustained over the 4-week treatment period ( mean reductions 60.1 and 1.4 ( μmol/L in the treated and control groups , respectively ) . Normal ammonia levels were attained in 14 of 16 patients receiving L-carnitine . Based on psychometric test results , seven patients ( 43.7 % ) in the L-carnitine group and five ( 45.5 % ) in the control group had SHE at baseline . L-carnitine treatment for 4 weeks caused a net overall improvement in psychometric test results compared with controls . No clinical ly significant adverse events were reported and all patients receiving L-carnitine reported subjective improvements in their condition . Conclusions : Results of this preliminary study indicate that L-carnitine reduces hyperammonaemia and improves the clinical symptoms of SHE in patients with hepatic cirrhosis Background : The health status of employees with chronic hepatitis C has major implication s for organizations and labour market . Objectives : To assess the effects of Acetyl-L-Carnitine administration on work productivity , daily activity , and fatigue in subjects with chronic hepatitis C treated with Pegylated-Interferon-α2b and Ribavirin .  Patients and Methods : 
    Output:
    
Due to the limited number of included trials , short-term treatment , and inadequate reporting , we were unable to draw any conclusions about the efficacy or safety of L-carnitine for cognitive enhancement in healthy adults .