Carnitine Ester Profile Research Articles

Determination of carnitine ester profile in the children with type 1 diabetes: a valuable step towards a better management

Objective: This study is designed to investigate the levels of carnitine and acylcarnitines (ACs) in the children with diabetes type 1 compared to the healthy subjects. Methods: Forty-two type 1 diabetic children and healthy subjects were recruited in the study, respectively. In addition to FBS and Hb A1C, free carnitine and ACs in butyl-ester form in the fasting blood samples were assessed by isotope dilution mass spectrometry for all diabetics and controls using the tandem mass spectrometry system. Results: Diabetic patients had a higher level of C, C4, C6, C14, C18:2, and C18:2OH. Females had elevated C14:2 compared to the males. The C18:2 and C18:2OH levels were elevated as the Hb A1C level increased. The C18:2, C14OH were mostly increased in the prediabetic and diabetic patients, respectively. Conclusion: Increased ACs level indicates the increased acyl-CoA intermediates for the fatty acids and amino acids oxidation.

Differences in Circulating Carnitine Status of Preterm Infants Fed Fortified Human Milk or Preterm Infant Formula

The aim of the study was to compare plasma carnitine profiles in fortified human milk (HM)-fed preterm infants or formula-fed preterm infants. Plasma acylcarnitine concentrations were determined in 20 formula-fed and 18 HM-fed preterm infants (birth weights between 1000 and 2200 g) by isotope dilution ESI MS/MS technique on study days 0, 14, and 28. Concentrations of free carnitine (FC) and different acylcarnitines did not change during the 4 weeks of the study in infants fed HM. In contrast, in infants fed formula FC increased markedly (day 0: 29.989 [16.646] μmol/L, median [interquartile range], day 14: 43.972 [8.455], P < 0.05) along with increases of short-chain esters (C2 day 0: 5.300 [3.272], day 14: 6.773 [2.127], P < 0.05; C3 day 0: 0.070 [0.059], day 14: 0.110 [0.069], P < 0.05). In contrast, some medium-chain (C8:1, C12) and long-chain esters (C14, C16) decreased significantly in infant formula by day 14, whereas FC and C2 and C3 esters increased further by day 28 (FC: 47.672 [14.753], C2: 7.430 [4.688], C3: 0.107 [0.047]). The altered carnitine ester profile likely reflects active involvement of the carnitine molecule in the buffering, metabolism, and elimination of nonphysiological acyl moieties.

Effect of hemodialysis session on the dynamics of carnitine ester profile changes in l-carnitine pretreated end-stage renal disease patients

Carnitine deficiency is common in end-stage renal disease (ESRD) patients receiving hemodialysis (HD) treatment. We investigated the effects of L-carnitine supplementation on acyl carnitine (AC) profile and the changes of distinct ACs during a single HD session in long-term L-carnitine pretreated ESRD patients. Twenty non-diabetic adult patients and 37 healthy controls were studied. Blood samples were drawn before and after 12 weeks of carnitine supplementation, then hourly during an HD session, as well as 30 min after the end of the session. Free and individual AC plasma levels were determined by using ESI MS/MS technique. HD patients showed lower free- and total carnitine levels and elevated ACs and acyl/free carnitine ratio before carnitine supplementation. The L-carnitine supplementation resulted in dramatic elevation of all carnitine esters. The HD session induced a progressive decline in free, short-chain, and dicarboxylic ACs (~80 % of pre-HD amount was washed out); the decrease of medium-chain ACs proved to be more moderate (~60 % washed out), whereas the long-chain ACs remained unaffected. Already 30 min after HD, a substantial increase was seen in free carnitine concentration (reaching 26 % of predialysis level) and the ACs also started to replenish (to 21-52 % of predialysis levels), without further exogenous carnitine load. The washout induced by HD session results in variable depletion of short-, medium-, and long-chain carnitine esters in carnitine-pretreated patients; the recovery of the circulating carnitine esters from the body stores occurs within 30 min after the cessation of the HD procedure.

Dynamic adaptive changes of the serum carnitine esters during and after L-carnitine supplementation in patients with maintenance haemodialysis

Background. Here we report the serum carnitine ester profile during and after 1g iv/day L-carnitine supplementation in haemodialysis patients. Materials and methods. Seven patients were studied over 29 weeks. After a control day, 12 weeks of replacement therapy was introduced followed by 17 weeks of washout period. The serum acylcarnitine concentrations were determined by isotope dilution ESI MS/MS technique. Results. At baseline significantly decreased free carnitine (48%, p < 0.01) and a 1.5–16-fold elevation of 16 out of 27 acylcarnitines were detected in HD patients compared with the controls. On the last day of L-carnitine supplementation a 1.6–4.8-fold increase was observed in the acylcarnitine levels compared with day 0; the increase-profile was achieved in four different patterns. The increase rate was rapid and early saturable for C5, C5OH, C6DC, C8:1, C10DC and C18:2 esters, slower for C2, C4, C6, C18 and C18:1 esters, it was slowest and reached a late plateau for C3, C8DC, C14:2, C16 and C16:1, and finally almost gradual increase was seen for 11 acylcarnitines. Three months after the cessation of carnitine treatment marked concentration drops were found for almost all acylcarnitines (by 11–74 % of week 12, p < 0.05); the values further decreased over the five remaining weeks of the observation period. Conclusion. Carnitine administration affected the levels of circulating esters in different dynamics and kinetics suggesting a regulated, non-random adaptive reallocation of nutrients. A considerable washout was achieved 3 months after discontinuation of the supplementation; however, the profile still was suggestive for presence of rest of accumulated supplement.

Plasma carnitine ester profiles in Crohn's disease patients characterized for SLC22A4 C1672T and SLC22A5 G-207C genotypes

Crohn's disease (CD) is a chronic inflammatory bowel disorder caused by environmental and genetic factors. The purpose of this study was to analyse the possible influence of functional variants of genes of OCTN cation transporters on the carnitine ester profile of patients with CD. Genotyping for SLC22A4 1672C --> T, SLC22A5-207G --> C mutations and three common NOD2 variants (R702W, G908R and 1007finsC) were performed in 100 adult CD patients and in ninety-four healthy controls by direct sequencing. The carnitine ester profile was determined using ESI triple quadrupole tandem MS. Contrary to the NOD2/CARD15 mutations, none of the SLC variants showed increased prevalence in the CD group, the prevalence of TC haplotype did not differ between the patients and the controls. In the mixed group of CD patients the fasting propionyl- (0.243 (sem 0.008) v. 0.283 (sem 0.014) micromol/l), butyryl- (0.274 (sem 0.009) v. 0.301 (sem 0.013)) and isovalerylcarnitine (0.147 (sem 0.006) v. 0.185 (sem 0.009)) levels were decreased; while the level of octenoyl- (0.086 (sem 0.006) v. 0.069 (sem 0.005)), myristoleyl- (0.048 (sem 0.003) v. 0.037 (sem 0.003)), palmitoyl- (0.140 (sem 0.005) v. 0.122 (sem 0.004)) and oleylcarnitine (0.172 (sem 0.006) v. 0.156 (sem 0.008); P < 0.05 in all comparisons) were increased. After sorting the patients into SLC22A genotype-specific subgroups, no significant differences could be observed between them. The carnitine ester profile data suggest selective involvement of the carnitine esters in CD patients, probably due to their altered metabolism.

SUCLA2 mutations are associated with mild methylmalonic aciduria, Leigh-like encephalomyopathy, dystonia and deafness

One pedigree with four patients has been recently described with mitochondrial DNA depletion and mutation in SUCLA2 gene leading to succinyl-CoA synthase deficiency. Patients had a Leigh-like encephalomyopathy and deafness but besides the presence of lactic acidosis, the profile of urine organic acid was not reported. We have studied 14 patients with mild 'unlabelled' methylmalonic aciduria (MMA) from 11 families. Eight of the families are from the Faroe Islands, having a common ancestor, and three are from southern Italy. Since the reaction catalysed by succinyl-CoA synthase in the tricarboxylic acid (TCA) cycle represents a distal step of the methylmalonic acid pathway, we investigated the SUCLA2 gene as a candidate gene in our patients. Genetic analysis of the gene in the 14 patients confirmed the defect in all patients and led to the identification of three novel mutations (p.Gly118Arg; p.Arg284Cys; c.534 + 1G --> A). The defect could be convincingly shown at the protein level and our data also confirm the previously described mitochondrial DNA depletion. Defects in SUCLA2 can be found at the metabolite level and are defined by mildly elevated methylmalonic acid and C4-dicarboxylic carnitine concentrations in body fluids in association with variable lactic acidosis. Clinically the diagnosis should be considered in patients with early/neonatal onset encephalomyopathy, dystonia, deafness and Leigh-like MRI abnormalities mainly affecting the putamen and the caudate nuclei. The frequency of the mutated allele in the Faroese population amounted to 2%, corresponding with an estimated homozygote frequency of 1 : 2500. Our data extend knowledge on the genetic defects causing MMA. Our patients present with an early infantile Leigh-like encephalomyopathy with deafness, and later on a progressive dystonia. Mild MMA, lactic acidosis and specific abnormalities in the carnitine ester profile are the biochemical hallmarks of the disease. In view of the frequency of the mutated allele on the Faroe Islands, measures become feasible to prevent the occurrence of the disease on the islands. We confirm and extend the findings on this inborn error of metabolism in the TCA cycle that must be carefully investigated by accurate metabolite analyses.

Changes of plasma fasting carnitine ester profile in patients with ulcerative colitis

To determine the plasma carnitine ester profile in adult patients with ulcerative culitis (UC) and compared with healthy control subjects. Using ESI triple quadrupole tandem mass spectrometry, the carnitine ester profile was measured in 44 patients with UC and 44 age- and sex-matched healthy controls. There was no significant difference in the fasting free carnitine level between the patients with UC and the healthy controls. The fasting propionyl- (0.331 +/- 0.019 vs 0.392 +/- 0.017 micromol/L), butyryl- (0.219 +/- 0.014 vs 0.265 +/- 0.012), and isovalerylcarnitine (0.111 +/- 0.008 vs 0.134 +/- 0.008) levels were decreased in the UC patients. By contrast, the level of octanoyl-(0.147 +/- 0.009 vs 0.114 +/- 0.008), decanoyl- (0.180 +/- 0.012 vs 0.137 +/- 0.008), myristoyl- (0.048 +/- 0.003 vs 0.039 +/- 0.003), palmitoyl- (0.128 +/- 0.006 vs 0.109 +/- 0.004), palmitoleyl- (0.042 +/- 0.003 vs 0.031 +/- 0.002) and oleylcarnitine (0.183 +/- 0.007 vs 0.163 +/- 0.007; P < 0.05 in all comparisons) were increased in the patients with UC. Our data suggest selective involvement of the carnitine esters in UC patients, probably due to their altered metabolism.

Plasma carnitine ester profile in adult celiac disease patients maintained on long-term gluten free diet

To determine the fasting plasma carnitine ester in patients with celiac disease. We determined the fasting plasma carnitine ester profile using ESI triple quadrupol mass spectrometry in 33 adult patients with biopsy-confirmed maturity onset celiac disease maintained on long term gluten free diet. The level of free carnitine did not differ as the celiac disease patients were compared with the healthy controls, whereas the acetylcarnitine level was markedly reduced (4.703 +/- 0.205 vs 10.227 +/-0.368 nmol/mL, P<0.01). The level of propionylcarnitine was 61.5%, butyrylcarnitine 56.9%, hexanoylcarnitine 75%, octanoylcarnitine 71.1%, octenoylcarnitine 52.1%, decanoylcarnitine 73.1%, cecenoylcarnitine 58.3%, lauroylcarnitine 61.5%, miristoylcarnitine 66.7%, miristoleylcarnitine 62.5% and oleylcarnitine 81.1% in the celiac disease patients compared to the control values, respectively (P<0.01). The marked decrease of circulating acetylcarnitine with 50-80 % decrease of 11 other carnitine esters shows that the carnitine ester metabolism can be influenced even in clinically asymptomatic and well being adult celiac disease patients, and gluten withdrawal alone does not necessarily normalize all elements of the disturbed carnitine homeostasis.

On the plasma carnitine ester profile in adult celiac disease

Background: The majority of the carnitine (C) reserves derive from alimentary sources, the site of the absorption located to the small intestines. C absorption is known to be influenced by the damaged intestinal uptake.

Plasma carnitine ester profile in Crohn's disease

Background: Very recent data show that the human OCTN1 and OCTN2 carnitine (C) transporter orthologs likely map to the IBD5 locus at 5q31, which has been suggested to confer susceptibility to Crohn's disease (CD). Therefore, a link between a pathogenic role of C and the CD can exist. The circulating C ester profile has not been investigated in CD.

Quantification of carnitine esters by high-performance liquid chromatography: Effect of feeding medium-chain triglycerides on the plasma carnitine ester profile

A high-performance liquid chromatographic (HPLC) technique was developed using commercially available derivatization reagents and commonly used reversed-phase HPLC column chemistry to analyze plasma samples for their carnitine ester content. The method proved to be sufficiently sensitive to determine changes in the carnitine ester profile in plasma resulting from metabolic disorders or metabolic insults. The method was tested using plasma samples obtained from pigs fed medium-chain triglycerides (MCT) of different chain lengths (four to seven carbons). The MCT feeding was associated with transient increases in plasma carnitine and carnitine esters, and feeding odd-chain MCT (tri-C 5 or tri-C 7) led to elevated levels of propionylcarnitine in plasma.