***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 
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    ***EXAMPLES*** 
    Input: Parenterally fed preterm neonates are known to be at risk for carnitine deficiency . We studied substrate utilization in low-birth-weight infants receiving total parenteral nutrition ( TPN ) with ( A ) and without ( B ) supplementation of 48 mg carnitine.kg-1.d-1 on days 4 - 7 ( birth weights 1334 + /- 282 vs 1318 + /- 248 g , gestational age 32 + /- 2 vs 32 + /- 2 wk , A vs B , respectively ) . TPN consisted of 11 g glucose.kg-1.d-1 and 2.4 g.kg-1.d-1 of both protein and fat . Plasma carnitine concentrations at day 7 were for free carnitine 11.8 + /- 5.0 vs 164 + /- 56 mumol/L and for acyl carnitine 3.8 + /- 2.0 vs 33.9 + /- 15.4 mumol/L , respectively . Indirect calorimetry at day 7 showed a higher fat oxidation ( 0.21 , -0.31 to + 0.60 vs 1.18 , 0.70 to 1.95 g. kg-1.d-1 , respectively , P less than 0.02 , median and interquartile range ) in group B and a higher protein oxidation ( 0.37 , 0.30 - 0.43 vs 0.63 , 0.53 - 0.88 g.kg-1.d-1 , P less than 0.001 ) . The time to regain birth weight was also higher in group B ( 7 , 5.5 - 9 vs 9 , 7 - 14 d , P less than 0.05 ) . Carnitine supplementation and calorie intake were the best explanatory variables for metabolic rate ( R2 = 0.45 , P less than 0.002 ) . We conclude that carnitine supplementation of TPN in this dosage does not seem advisable To investigate whether L-carnitine supplementation may correct nutritional carnitine deficiency and associated metabolic disturbances in premature infants receiving total parenteral nutrition , an intravenous fat tolerance test ( 1 gm/kg Intralipid over four hours ) was performed in 29 premature infants 6 to 10 days of age ( 15 receiving carnitine supplement 10 mg/kg . day L-carnitine IV , and 14 receiving no supplement ) .  Total carnitine plasma values were normal or slightly elevated in supplemented but decreased in nonsupplemented infants . In both groups , fat infusion result ed in an increase in plasma concentrations of triglycerides , free fatty acids , D-beta-hydroxybutyrate , and short-chain and long-chain acylcarnitine , but total carnitine values did not change . After fat infusion , the free fatty acids/D-beta-hydroxybutyrate ratios were lower and the increase of acylcarnitine greater in supplemented infants of 29 to 33 weeks ' gestation than in nonsupplemented infants of the same gestational age . This study provides evidence that premature infants of less than 34 weeks ' gestation requiring total parenteral nutrition develop nutritional carnitine deficiency with impaired fatty acid oxidation and ketogenesis .  Carnitine supplementation improves this metabolic disturbance BACKGROUND & AIMS Carnitine may be considered conditionally essential in the neonatal population . The purpose of this study was to evaluate the effects of long-term carnitine supplementation on total carnitine status and morbidity in premature neonates . METHODS In this prospect i ve , r and omized , placebo-controlled , double-blinded study , premature neonates received carnitine supplementation ( 20mg/kg/day ) or placebo .  Plasma ( nmol/ml ) and red blood cell ( RBC ) ( nmol/mg hemoglobin ) total carnitine concentrations , 24-h nitrogen excretion , intake and weight , and respiratory , gastroesophageal , and infectious morbidity were assessed . RESULTS Twenty-nine neonates ( 13 placebo , 16 carnitine ; 27+/-2 weeks gestation ; 976+/-259 g birthweight ) were studied for up to 8 weeks . Plasma total carnitine concentrations exceeded the reference range in the carnitine group ( weeks 1 - 8 ) ; however , concentrations did not reach reference range until week 4 in the placebo group . RBC total carnitine concentrations increased , but remained below reference range in both the carnitine ( weeks 1 - 6 ) and placebo ( weeks 1 - 8 ) groups . Carnitine group neonates regained their birthweight more rapidly than placebo group neonates ( day of life 11.8+/-6 vs. 16.9+/-6.3 , P=0.034 ) . In addition , percent periodic breathing calculated from cardiopulmonary trend monitor data ( weeks 1 - 8 ) was lower in the carnitine group ( 0.4+/-0.9 vs. 1.4+/-1.9 , P=0.014 ) . There was no difference with respect to other markers of respiratory , gastroesophageal and infectious morbidity or nitrogen balance . CONCLUSIONS Carnitine supplementation at 20mg/kg/day results in increased plasma and RBC total carnitine concentrations , has a positive effect on catch-up growth , and may improve periodic breathing in premature neonates OBJECTIVE Carnitine is thought to be a conditionally essential biological cofactor for premature infants . A preliminary study suggested that carnitine could significantly reduce  apnea of prematurity .  The objective of this study was to evaluate critically the role of carnitine in idiopathic apnea of prematurity and to determine whether the use of carnitine would facilitate discontinuation of mechanical ventilatory support , shorten the duration of ventilatory support , and reduce the amount of time that such infants are exposed to both mechanical ventilation and oxygen . We also wanted to determine the effects of supplemental carnitine on weight gain , time to regain birth weight , time to achieve full enteral feedings , and length of hospital stay . METHODS A prospect i ve , r and omized , blinded trial was conducted on 44 preterm infants who were from the same neonatal intensive care unit and who were < or = 32 weeks ' gestational age with a postnatal age < 48 hours and a birth weight < 1500 g and required total parenteral nutrition ( TPN ) . Infants were r and omized to receive carnitine supplementation or placebo without crossover . Carnitine-supplemented infants received 30 mg/kg/d carnitine in their TPN until the they were tolerating 120 mL/kg/d enteral feedings , and then they received 30 mg/kg/d oral carnitine . The placebo group received TPN without supplemental carnitine ; when they tolerated 120 mL/kg/d enteral feedings , they received an oral placebo . The 2 groups continued on their respective supplemental carnitine or placebo until 34 weeks ' adjusted age , at which time the study period was completed . Twelve-hour cardiorespiratorygrams to record heart rate , respiratory impedance , and oxygen saturation , and a nasal thermistor to detect expiratory airflow were performed every 4 days on 3 occasions and at 30 and 34 weeks ' adjusted age . Plasma carnitine levels were measured at day 14 . RESULTS There were no significant differences between the 2 groups in the occurrence of apnea as detected by cardiorespiratorygram or nursing observation . There were no significant differences between the groups in regard to total days on ventilator , days of nasal continuous positive airway pressure , time to regain birth weight , time to reach enteral feedings of 120 mL/kg/d , discharge weight , adjusted age at discharge , need for oxygen at 28 days ' and 36 weeks ' adjusted age , or length of stay . The plasma carnitine level was a median of 15.5 micromol/L ( range : 7.6 - 30.5 ) for the placebo infants compared with a median of 195.3 micromol/L ( range : 71.7 - 343.6 ) for the carnitine infants . CONCLUSIONS In this blinded , r and omized , placebo-controlled study , we found that infants who received supplemental carnitine did not demonstrate any reduction in apnea of prematurity , ventilator or nasal continuous positive airway pressure days , or the need for supplemental oxygen therapy . Although carnitine may be of significant nutritional benefit for very low birth weight infants , our study does not support its use to reduce apnea of prematurity or decrease dependence on mechanical ventilation OBJECTIVE Systemic carnitine deficiency may present with apnea , hypotonia , and  poor growth . Premature infants often manifest these symptoms and are at risk of developing carnitine deficiency because of immaturity of the biosynthetic pathway , lack of sufficient predelivery transplacental transport , and lack of sufficient exogenous supplementation . This study was undertaken to examine the effect of carnitine supplementation in premature infants . METHODS Eighty preterm infants < 1500 g were enrolled in a prospect i ve , double-blind , placebo-controlled study of carnitine supplementation within 96 hours of delivery . Growth , length of hospital stay , and frequency and severity of apnea were the primary outcome measures . RESULTS Weight gain and change in length , fronto-occipital head circumference , mid arm circumference , and triceps skinfold thickness were similar between the carnitine-supplemented and placebo groups . The amount and severity of apnea and the overall length of hospitalization were also similar between the 2 groups . The carnitine levels in the supplemented group were significantly higher than in the placebo group at 4 and 8 weeks after study entry . CONCLUSION Although preterm infants < 1500 g have low carnitine levels , routine supplementation with carnitine has no demonstrable effect on growth , apnea , or length of hospitalization and thus seems to be unnecessary AIMS To evaluate the effect of L-carnitine supplementation ( 25 mg/kg/d ) on the growth and incidence of hypoglycaemia in preterm infants . METHODS A double blind , placebo controlled r and omised trial , stratified for gestational age , was conducted of 86 preterm infants between 28 and 34 gestational weeks . The median gestational ages in the carnitine group and placebo groups were 30.7 weeks ( range 28.0 to 33.6 ) and 31.4 weeks ( range 28.0 to 33.9 ) , respectively . The median birthweights were 1.557 kg ( range 0.944 to 2.275 ) and 1.645 kg ( range 0.885 to 2.545 ) , respectively . RESULTS Mean plasma free carnitine concentrations were below values for normal term infants in both groups on day 1 ( carnitine group 44.8 μmol/l , placebo group 25.5 μmol/l ) in the placebo group on day 7 ( 50.7 μmol/l ) , but in neither group on days 14 and 28 . Total , free , and acylcarnitine concentrations were significantly increased in both urine and blood in the L-carnitine group . There was no significant difference between the placebo and carnitine supplemented groups in growth rate , as assessed by weight , length , skinfold thickness and head circumference measurements , or in the incidence of episodes of hypoglycaemia . CONCLUSION The addition of carnitine as a nutritional supplement at a dose of 25mg/kg/day did not improve growth in our group of preterm infants nor protect them from episodes of hypoglycaemia OBJECTIVE Carnitine transfer across the placenta occurs predominantly during the third trimester . Unless L-carnitine is provided , very preterm infants develop carnitine deficiency . Although breast milk and infant formulas contain L-carnitine , parenteral nutrition solutions do not routinely provide L-carnitine . We hypothesized that prolonged L-carnitine supplementation in very preterm infants would improve weight gain and shorten length of stay in the hospital . STUDY DESIGN The study was a double-blind parallel placebo-controlled  r and omized clinical trial . Eligible patients were < 29 weeks of gestation , < 72 hours of age , and did not have a potentially life-threatening congenital malformation or hereditary metabolic disorder . Patients were stratified by gestational age ( 23 to 256/7 and 26 to 286/7 weeks ) , and r and omized to receive , either L-carnitine at a dose of 50 μmol/kg/day , or placebo . Carnitine was provided intravenously until the infants tolerated 16 ml/day of feeds . The sample size was calculated to have 80 % power to detect a 10 % increase in weight gain from birth until 36 weeks of postmenstrual age or discharge from the hospital . Secondary outcome variables included food efficiency ( defined as weight gain divided by caloric intake ) , weight gain at 4 weeks of age , time to regain birth weight and length of stay . RESULTS Among the 63 infants enrolled in the trial , 32 were r and omized to L-carnitine and 31 to placebo . L-Carnitine supplementation did not significantly affect average daily weight gain from birth until 36 weeks or hospital discharge , 
    Output:
    
The present results prove that routine supplementation in the parenteral nutrition of preterm newborns may help to increase carnitine levels , but neither a relevant improvement in the lipid profile , or an increase in weight gain , or a decrease in morbimortality or reduction of hospital stay could be demonstrated .
More studies are needed in preterm infants to know whether routine supplementation of L-carnitine in neonates requiring total parenteral nutrition for a long time would provide any clinical benefit