Esterified Carnitine Research Articles

Exploring the functional and metabolic effects of adding garra fish meal to a plant-based broiler chicken diet.

The present study evaluated the metabolic and functional effects of adding garra meal to a broiler chicken diet. Three hundred twenty Sasso-breed day-old chicks were randomly assigned to four dietary treatments with either 0, 10, 20 or 30% garra meal added on top of formulated starter and grower basal diets. The experiment lasted for 42days. Feed intake and body weight gain increased at the starter and grower phases of broilers with garra meal addition (P < 0.05). Broiler chickens fed 30% garra meal were more efficient in converting feed to body weight and yielded the highest carcass weight (P < 0.05). Crude protein ileal digestibility coefficient was higher with 20% (76.2%), and crude fat with 20 (92.1) and 30% (92.6%) garra meal receiving groups (P < 0.05). The increase in individual and total esterified carnitine concentrations in dried blood spots demonstrated the elevated metabolic rate with garra meal addition (P < 0.05). A better supply of glucogenic substrate to the citric acid cycle was seen with garra meal addition due to the increase of propionylcarnitine to acetylcarnitine ratio (P < 0.05) without any apparent effect on ketogenesis in terms of serum 3-hydroxybutyrylcarnitine to acetylcarnitine ratio. Yet, it likely showed that part of the amino acids from garra meal were used as glucogenic substrate (P < 0.05). Histomorphometry data showed 20% garra meal addition elevated villus height, crypt depth and their ratio in the proximal parts of the small intestine (duodenum and jejunum) with the opposite results observed in the more distal part (ileum) with the highest for the control group (P < 0.05). It can be concluded that garra meal improved broiler performance when added to a plant-based diet and only few parameters warranted for caution when using more up to 30% garra meal addition. Beyond growth performance, garra meal generated a shift to a more efficient digestion, absorption and nutrient metabolism.

Biochemical phenotyping of multiple myeloma patients at diagnosis reveals a disorder of mitochondrial complexes I and II and a Hartnup-like disturbance as underlying conditions, also influencing different stages of the disease

The aim of this study was to identify novel plasma metabolic signatures with possible relevance during multiple myeloma (MM) development and progression. A biochemical quantitative phenotyping platform based on targeted electrospray ionization tandem mass spectrometry technology was used to aid in the identification of any eventual perturbed biochemical pathway in peripheral blood plasma from 36 MM patients and 73 healthy controls. Our results showed that MM cases present an increase in short and medium/long-chain species of acylcarnitines resembling Multiple AcylCoA Dehydrogenase Deficiency (MADD), particularly, associated with MM advanced International Staging System (ISS). Lipids profile showed lower concentrations of phosphatidylcholine (PC), lysophosphatidylcholine (LPC) and sphingomyelins (SM) in the MM patients and its respective ISS groups. MM cases were accompanied by a drop in the concentration of essential amino acids, especially tryptophan, with a significant inverse correlation between the progressive drop in tryptophan with the elevation of β2-microglobulin, with the increase in systemic methylation levels (Symmetric Arginine Dimethylation, SDMA) and with the accumulation of esterified carnitines in relation to free carnitine (AcylC/C0). Serotonin was significantly elevated in cases of MM, without a clear association with ISS. Kynurenine/tryptophan ratio demonstrates that the activity of dioxigenases is even higher in the cases classified as ISS 3. In conclusion, our study showed that MM patients at diagnosis showed metabolic disorders resembling both mitochondrial complexes I and II and Hartnup-like disturbances as underlying conditions, also influencing different stages of the disease.

Analytical Methods for Quantitative Plasma Carnitine Determination.

Carnitine is an essential molecule for mitochondrial beta-oxidation of long-chain fatty acids and other cellular functions. Several rare, inherited disorders of carnitine metabolism occur in humans, and secondary carnitine deficiency is an important feature in a variety of clinical settings. Many of these conditions can be detected via quantitative analysis of free and esterified carnitine in plasma or urine, which thus offers an effective means for assessing the transport and initial processing of fatty acids. Here, we describe some of the methods most commonly employed for quantification of plasma carnitine and consider some of the advantages and disadvantages of these approaches. © 2019 by John Wiley & Sons, Inc.

Are low birth weight children predisposed to renal loss of carnitine?

Aim: The plasma homeostasis of both free and esterified carnitines is mostly regulated by renal tubular reabsorption, which may be disturbed in low birth weight children. The aim of study was to check whether disturbances in excretion of l-carnitine (LC) and its main ester, acetyl-carnitine (ALC), may be the result of renal dysfunction in low birth weight children (LBW).Methods: This study included 59 LBW children (2165 g [1490–2440]) and 22 children with normal birth weight as a reference group (3500 g [3275–3650]). Subjects were divided into three groups: 0–3 months, 4–12 months and over 1 year at the time of testing. Urinary levels of carnitine were measured spectrophotometrically.Results: The urine excretion of Free LC, Free LC/cr, Total LC and Total LC/cr. Were significantly higher in 0–3 and 4–12-month old LBW infants study groups when compared to the reference groups. We found statistically significant higher urine excretion of ALC and ALC/cr. in all age groups of LBW infants compared to the reference group. There was a negative correlation between birth weight and free LC/cr. (r= −0.3, p < .05), Total LC/cr. (r= −0.34, p < .05), and ALC/cr. (r= −39, p < .05), and in the children >12-month-old strong negative correlation between eGFR and free LC/cr. (r= −0.6, p < .05), Total LC/cr. (r= −0.61, p < .05), ALC/cr. (r= −0.61, p < .05.)Conclusion: Higher urine excretion of both LC and ALC and its negative correlation with birth weight and eGFR may reflect some degree of renal dysfunction in LBW infants.

Severe cardiomyopathy in a young patient with complete deficiency of adipose triglyceride lipase due to a novel mutation in PNPLA2 gene

Severe cardiomyopathy in a young patient with complete deficiency of adipose triglyceride lipase due to a novel mutation in PNPLA2 gene

L-Carnitine supplementation during suckling intensifies the early postnatal skeletal myofiber formation in piglets of low birth weight1

Piglets of low birth weight exhibit a reduced total number of skeletal myofibers at birth and throughout life compared with piglets of middle and heavy birth weight, which is associated with impaired (lean) growth and quality of carcass and meat at market weight. We investigated the effect of L-carnitine supplementation to suckling piglets of different birth weights on early postnatal myofiber formation, muscle growth, and body composition. A total of 48 piglets of low (LW) and middle (MDW) birth weight from 9 German Landrace gilts received 400 mg of L-carnitine (carnitine, n = 25) or a placebo (control, n = 23) once daily from d 7 to 27 of age and were slaughtered on d 28 of age (weaning). Carnitine-supplemented piglets deposited less fat as indicated by a reduced proportion of perirenal (P = 0.1) and intramuscular fat (P = 0.05). Circulating glucose concentrations tended to be greater in supplemented LW piglets (P = 0.13). The concentration of carnitine in semitendinosus (STN) muscle was approximately doubled (P < 0.001) by supplementation, with emphasis on the proportion of esterified carnitine. The ratio of lactate dehydrogenase to isocitrate dehydrogenase tended (P = 0.12) to be smaller in STN muscle of supplemented piglets, indicating a more oxidative muscle metabolism. The total number of STN myofibers was increased by 13% (P = 0.02) in supplemented LW piglets, thereby reaching the unchanged level of MDW littermates. In addition, supplemented LW piglets displayed a 2.4-fold mRNA expression of the gene encoding the embryonic isoform of the myosin heavy chain in STN muscle than control piglets (P = 0.05), but there were no differences in the proportion of fibers positively staining for the embryonic myosin isoform. L-carnitine-supplemented piglets exhibited a greater DNA:protein ratio (P = 0.02) in STN muscle, which resulted from a greater DNA concentration (P = 0.04). However, the STN muscle of L-carnitine-supplemented piglets was not less mature as indicated by unchanged myofiber size, creatine kinase activity, and protein concentration. The results indicate that energy balance has been improved through intensified fatty acid oxidation. As a consequence, myogenic proliferation appears to be stimulated, which in LW piglets may have contributed to a compensatory increase in myofiber number. Thus, piglets, particularly those of low birth weight, could profit from an early postnatal L-carnitine supplementation, which may attenuate the negative consequences of low birth weight on body composition and meat quality at market weight.

Advances in Carnitine in Chronic Uremia

Carnitine is a conditionally essential metabolite that plays a critical role in cell physiology. Carnitine is necessary for fatty acid transport to sites of beta-oxidation in the mitochondria, where it helps to prevent organic acid accumulation. Because of these key regulatory functions, carnitine represents a crucial determinant of mitochondrial energy metabolism, whose deficiency may lead to metabolic and clinical disturbances. Loss of carnitine through dialytic membranes occurs in maintenance hemodialysis, resulting in potential carnitine depletion and relative increments of esterified carnitine forms. Carnitine supplementation has been shown to counteract such alterations and may be associated with clinical benefit. In particular, carnitine supplementation in patients on hemodialysis may enhance response to erythropoietin, resulting in improved hematologic status. Carnitine was also reported to improve exercise tolerance and intradialytic symptoms. Carnitine supplementation may enhance insulin resistance, inflammatory and antioxidant status, protein balance, lipid profile, and cardiac function. Carnitine administration can be useful for selected patients on dialysis who do not adequately respond to standard therapy.

Metabolic changes associated with hyperammonemia in patients with propionic acidemia

Propionic acidemia is an autosomal recessive disorder caused by deficiency of propionyl CoA carboxylase. Affected patients can develop severe hyperammonemia, whose causative mechanism is unknown. In this study, we monitored changes in metabolic parameters associated with hyperammonemia in patients with propionic acidemia. Levels of ammonia were correlated with plasma levels of individual amino acids and carnitine and with urinary organic acids. Significance of correlations was determined with analysis of variance. Hyperammonemia positively correlated with an increase in branched-chain amino acids (leucine and isoleucine) and a decrease in glutamine/glutamate and esterified carnitine. The urinary excretion of methylcitric acid, formed by the combination of propionic acid with oxaloacetate from the Krebs cycle, increased while that of citric acid decreased with hyperammonemia. These results suggest that in propionic acidemia, hyperammonemia is triggered by catabolism with the accumulation of propionic acid derivatives. The decrease of the plasma levels of glutamine/glutamate with hyperammonemia in patients with propionic acidemia indicates that the mechanism producing hyperammonemia differs from that in urea cycle defects. The increase in methylcitric acid and decline in citric acid urinary excretion suggest that hyperammonemia in propionic acidemia might be related to inability to maintain adequate levels of glutamine precursors through a dysfunctional Krebs cycle.

Plasma and urinary carnitine and acylcarnitines in chronic fatigue syndrome

Contradictory reports have suggested that serum free carnitine and acylcarnitine concentrations are decreased in patients with chronic fatigue syndrome (CFS) and that this is a cause of the muscle fatigue observed in these patients. Others have shown normal serum free carnitine and acylcarnitines in similar patients. We report here studies on free, total and esterified (acyl) carnitines in urine and blood plasma from UK patients with CFS and three control groups. Plasma and timed urine samples were obtained from 31 patients with CFS, 31 healthy controls, 15 patients with depression and 22 patients with rheumatoid arthritis. Samples were analysed using an established radioenzymatic procedure for total, free and esterified (acyl) carnitine. There were no significant differences in plasma or urinary total, free or esterified (acyl) carnitine between UK patients with CFS and the control groups or in renal excretion rates of these compounds. The data presented here show that, in the CFS patients studied, there are no significant abnormalities of free or esterified (acyl) carnitine. It is thus unlikely that abnormalities in carnitine homeostasis have any significant role in the aetiology of their chronic fatigue.

Abnormal concentrations of esterified carnitine in bile

The etiology of acute liver failure in children is unknown in a large number of cases. Defects in fatty acid oxidation have been shown to lead to severe liver injury. This retrospective analysis examined the bile acylcarnitine profiles of 27 children with acute liver failure who underwent liver transplantation or died. Results were compared with 758 postmortem samples from individuals without acute liver failure. Cumulative amounts of free carnitine, medium- or long-chain species in excess of the 95th percentile of the control group were considered abnormal. Fourteen samples had normal profiles. Three had markedly elevated concentrations of free carnitine, whereas ten showed elevations in medium- or long-chain species. The relative risk of death was 2.86 (95% confidence interval, 1.08-7.54, P = .01) in the 10 children with elevated concentrations of medium- or long-chain species compared with those with normal analyses. Overall, medium- and long-chain acylcarnitines were increased in those patients who died compared with survivors, (dead vs. alive; medium-chain, 187 +/- 74 vs. 32 +/- 12 micromol/L, P = .008; long-chain, 146 +/- 74 vs. 15 +/- 8 micromol/L, mean +/- standard error of the mean, P = .018). These studies describe biliary free and esterified carnitine profiles in children with acute liver failure. In conclusion, the findings raise the hypothesis that abnormalities in fatty acid oxidation may predispose to a worse outcome in acute liver failure.

Carnitine Replacement in End‐Stage Renal Disease and Hemodialysis

In patients with chronic renal failure, not yet undergoing hemodialysis (HD), plasma acylcarnitines accumulate in part due to a decreased renal clearance of esterified carnitine moieties. In these patients, a high acylcarnitine/free-carnitine ratio is usually found in plasma. Patients undergoing maintenance HD, usually present with plasma carnitine insufficiency, due to accumulation of metabolic intermediates combined with impaired carnitine biosynthesis, reduced protein intake and increased removal via HD. Plasma carnitine concentrations rapidly decrease to 40% of baseline level during the dialysis session, with a slow restoration of the carnitine concentration during the interdialytic period, mainly from organs of storage (skeletal muscle). Dietary intake also plays an important role in carnitine homeostasis of HD patients since the prevalence of malnutrition ranges from 18% to 75% of these cases. This could differentially affect various body compartments, with clinical consequences such as impaired muscle function, decreased wound healing, altered ventilatory response, and abnormal immune function. Repeated hemodialytic treatments are associated with decreased carnitine stores in skeletal muscle. The administration of intravenous L-carnitine (LC) postdialysis replenishes the free carnitine removed from the blood and contributes to replenishment of muscle carnitine content. LC supplementation in selected uremic patients may yield clinical benefits by ameliorating several conditions, such as erythropoietin-resistant anemia, decreased cardiac performance, intradialytic hypotension, muscle symptoms, as well as impaired exercise and functional capacities. Furthermore, LC may positively influence the nutritional status of HD patients by promoting a positive protein balance, and by reducing insulin resistance and chronic inflammation, possibly through an effect on leptin resistance.

L-carnitine transport in kidney of normotensive, Wistar-Kyoto rats: effect of chronic L-carnitine administration.

To examine the effect of long-term administration of L-carnitine on L-carnitine transport in renal brush-border membrane vesicles (BBMVs) from normotensive, Wistar-Kyoto rats. Rats (n = 20) were orally administered 0.2 g carnitine/kg body weight per day for a total period of 8 weeks. Kinetic parameters of L-carnitine uptake were calculated by non-linear regression, and the relative abundance of the carnitine transporter, OCTN2, was determined by Western blot analysis. Initial rates and maximal overshoot levels of Na+-dependent L-carnitine transport were significantly reduced in BBMVs from L-carnitine-treated rats compared with untreated animals. Similarly, the maximal transport rate (Vmax) of OCTN2 was lower in treated rats. However, no differences were observed in the Michaelis constant (Km) or the diffusion constant (Kd) between the two groups of animals. The amount of OCTN2 protein was also decreased in L-carnitine-fed rats, this reduction being similar to that of the Vmax. These results were accompanied by an increase in the serum levels and also in the renal excretion of both free and esterified carnitine in treated rats, indicating that the long-term administration of L-carnitine leads to increased renal carnitine clearance. These findings suggest a downregulation of OCTN2 at the renal level, in the presence of high levels of carnitine.

Gender and age differences in plasma carnitine, muscle strength, and exercise tolerance in haemodialysis patients.

Haemodialysis patients have impaired exercise tolerance that may be related to impaired carnitine availability and/or alterations in carnitine metabolism. As carnitine metabolism is sex- and age-related, we examined plasma free and esterified carnitine concentrations, muscle strength, and estimated exercise tolerance in female (n=51) and male (n=63) patients of different ages (18-86 years). Concentrations of free carnitine and acetylcarnitine were determined in the plasma of patients. Isometric handgrip strength was measured using a dynamometer while exercise tolerance was predicted from scores for self-reported walking distance on the level and on an incline. Plasma total carnitine concentration in the females was significantly lower than that of males (35.4+/-1.3 and 42.4+/-1.4 micro mol/l, respectively, P<0.01). This was almost entirely due to the lower plasma free carnitine concentration of females when compared with the males (20.6+/-0.9 and 26.3+/-1.1 micro mol/l, respectively, P<0.05). Furthermore, plasma free carnitine concentrations were negatively correlated with age in females (r=-0.45, P<0.001) even when the linear effects of haemoglobin, albumin, body weight, time on dialysis, and muscle strength were removed from the regression analysis (partial correlation coefficient; pcc=-0.43, P=0.018), but not in the males (r=0.03, P>0.05). Isometric handgrip strength and estimated exercise tolerance on the level were lower in females than males (138.9+/-10.9 and 259.0+/-15.2 N, P<0.001; and 3.5+/-0.2 and 4.3+/-0.2, P<0.05, respectively). Isometric handgrip strength and estimated exercise tolerance (walking distance on the level and on an incline) were positively correlated with plasma free carnitine concentrations in females, but not in the males. There was a strong relationship between plasma free carnitine concentrations and age in female patients, but not in males. It is unlikely that the reduction in plasma free carnitine in females was a direct causative factor in their reduced exercise tolerance, but probably reflects greater muscle de-conditioning/atrophy with age in female patients.

A heterozygote phenotype is present in the jvs +/− mutant mouse livers

The juvenile visceral steatosis ( jvs) mouse, having a mutation in the carnitine transporter gene Octn2, is a model of primary systemic carnitine deficiency in humans (SCD, OMIM 212140). Like humans with SCD, homozygous jvs −/− mice have hepatic and cardiac steatoses, reduced plasma and tissue carnitines, and increased urinary carnitine clearance. Because symptomatic heterozygotes have been reported for some fatty acid oxidation disorders, including SCD, we compared the jvs heterozygotes to normal control mice. We measured the free and esterified carnitine, total cholesterol, and triglycerides in adult liver samples, myocardium, and skeletal muscle. Our results indicate significant differences between the livers of nonfasting adult normal ( n=8) vs jvs heterozygotes ( n=8) ( means± SEM, p<0.01) for the following parameters: free carnitine, 2.28±0.36 nmol/ mg protein vs 0.41±0.13; total carnitine, 3.48±0.36 vs 1.27±0.25; triglycerides, 0.14±0.04 vs 0.39±0.02; and total cholesterol, 0.21±0.02 vs 0.39±0.04, but not for esterified carnitine, 1.18±0.17 vs 0.90±0.17 ( p>0.05). There is also a negative correlation between hepatic free carnitine and triglycerides from jvs heterozygotes ( p<0.05). Similar results were obtained with myocardium and skeletal muscle. We conclude that free and total carnitine levels are significantly lower in the heterozygote mouse liver and heart while triglyceride and total cholesterol levels are significantly higher. We speculate that in situations of lipolytic stress, some SCD heterozygotes might develop clinical symptoms of carnitine deficiency.

Metabolic and structural abnormalities in dogs with early left ventricular dysfunction induced by incessant tachycardia.

To assess morphologic and metabolic abnormalities in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP). 7 Beagles. Plasma carnitine concentrations were measured before and after development of ELVD induced by RRVP. At the same times, transvenous endomyocardial biopsy was performed, and specimens were submitted for determination of myocardial carnitine concentrations and histologic, morphometric, and ultrastructural examination. In 4 dogs in which baseline plasma total carnitine concentration was normal, RRVP induced a decrease in myocardial total and free carnitine concentrations and an increase in myocardial esterified carnitine concentration. In 3 dogs in which baseline plasma total carnitine concentration was low, plasma and myocardial carnitine concentrations were unchanged after pacing. Structural changes associated with pacing included perinuclear vacuolization in 3 dogs. Morphometric analyses indicated there was a decrease in myofiber cross-sectional diameter and area following pacing. Electron microscopy revealed changes in myofibrils and mitochondria following pacing. Results indicated that moderate to severe alterations in myocyte cytoarchitecture are present in dogs with ELVD induced by RRVP and that in dogs with normal plasma carnitine concentrations, myocardial carnitine deficiency may be a biochemical marker of ELVD. Results also indicated that transvenous endomyocardial biopsy can be used to evaluate biochemical and structural myocardial changes in dogs with cardiac disease.

A new caw of hepatic glycogen snthase deficiency. biochemical findings and comparison with reported cases

Hepatic glycogen synthase deficiency (GSD-0) is an autosomal recessive disorder first described in 1963. Fifteen cases in seven different families have been reported. Mutations in GYS2, the gene coding for liver glycogen synthase, were found in the four families studied. We report a new case of GSD-0 in a female patient born to healthy non-consanguineous French Canadian parents. She was referred for a family-history of hyperlipidemia at 7 years of age. In addition to increased plasma total cholesterol and triglyceride levels, workup revealed fasting hypoglycemia and ketonuria. Her only complaint was morning headaches. Growth and development were normal Physical exam including neurological exam was normal. Cerebral MRI and EEC were normal Biochemical findings consistent with the diagnosis included fasting hypoglycemia, ketonemia and hypoalaninemia, and postprandial hyperlactatemia and elevated plasma branched chain amino acid levels. Liver biopsy confirmed reduced glycogcn synthase activity. Ratio of active to inactive form of glycogen synthase was normal, suggesting reduced enzyme synthesis rather than synthesis of an inactive protein. Low hepatic glycogen content and mild to moderate liver stealosis were present. Plasma free carnitine concentrations decreased during fasting while esterified carnitine levels remained unchanged. In contrast to other cases, we twice observed an increase in blood glucose levels after administration of glucagon following 15 and 18 hours of fasting respectively (from 2.2 to 3.4 and 2.7 to 4.0 mmol/L respectively) Since her hepatic glycogen content was reduced, this might come from gluconcogenesis At 13 years of age, our patient still has fasting hypoglycemia although to a lesser degree. Her growth and intellectual development remain normal From our patient's clinical course and a review of the literature, we draw the following conclusions (1) non specific symptoms after overnight fasting were the presenting complaint in 6/16, 3 cases were brought to medical attention because of incidental findings, family history led to the diagnosis in 7 cases. (2) fasting hypoglycemia (16/16) and reduced liver glycogen content (8/8) are constant features, (3) other frequent biochemical findings include hyperlactatemia with feeding (13/16) and fasting hyperketonemia (9/16) and hypoalaninemia (8/16); (4) glucagon response after feeding is usually absent (4/6) but can be observed (2/6); (5) liver steatosis was observed in 5/8 cases. (6) growth and development are usually normal (12/16 and 13/16 respectively).

Dynamic changes of plasma acylcarnitine levels induced by fasting and sunflower oil challenge test in children.

The dynamic changes of plasma acylcarnitine levels in 1- to 7-y-old children during fasting and after the ingestion of sunflower oil were studied. Glucose, 3-hydroxybutyrate, acetoacetate, FFA, and individual plasma acylcarnitine levels were monitored in both conditions. Fasting experiments lasted for 20 h, and acylcarnitine concentrations were analyzed at 0, 15, and 20 h of fasting. During the fat load, acylcarnitine levels were analyzed at 0, 60, 120, and 180 min. In both tests, a generalized increase of all plasma straight-chain acylcarnitines was observed. Acetylcarnitine contributed the most to the increase of total esterified carnitine. In addition, we demonstrated that the relative increase of each individual acylcarnitine during enhanced fatty acid oxidation is tightly related to its molecular structure and chain length. Fasting as well as the fat load primarily resulted in an increase of unsaturated acylcarnitines. During fasting, C(12:1) and C(14:1) showed a relatively high increase, whereas after the fat load C(16:2) and C(14:2), metabolites of linoleic acid (66% of the fat load), were the main acylcarnitines that increased.

Effect of supplemental carnitine on body weight loss, proximate and lipid compositions and carnitine content of red sea bream (Pagrus major) during starvation

The effect of supplemental dietary carnitine on the body weight loss, lipid composition and carnitine content of dorsal muscle of red sea bream during starvation was investigated. Two experimental groups of red sea bream fingerlings were used. One group was fed a control diet (Diet 1; < 0.09 g carnitine/kg feed) for 30 days prior to starvation while the second group was fed a carnitine-supplemented diet (Diet 2; 4 g carnitine/kg feed). Then fish were deprived of feed for 30 days. During the feeding period, fish fed Diet 2 accumulated free-carnitine in their dorsal muscle. The acid-soluble acylcarnitine content remained constant, indicating a redistribution of free and esterified carnitine. Although the long-chain acylcarnitine in the dorsal muscle increased during starvation, no difference was observed in the long-chain acylcarnitine content between the carnitine and the control group. The higher concentration of carnitine in the diet prior to starvation clearly did not show any effect on body weight loss or on the proximate and fatty acid compositions of dorsal muscle nor on the fatty acid composition of the liver. Carnitine supplementation prior to starvation did not show any clear effect on lipid classes in dorsal muscle and liver or on crude lipid and water concentration in liver during starvation.

Decompensation of hepatic and cerebral acyl-CoA metabolism in BALB/cByJ mice by chronic riboflavin deficiency: restoration by acety1-L-carnitine

BALB/cByJ mice have an autosomal recessive deficiency of short-chain acyl-CoA dehydrogenase (SCAD) and show elevated excretion of urinary butyrylglycine, ethylmalonate, and methylsuccinate, which resembles the SCAD deficiency disorder in children. These mice are clinically normal, perhaps because of an efficient acyl-CoA conjugation system. We attempted to decompensate the acyl-CoA metabolism in mutant mice by chronic treatment with a riboflavin-deficient diet for 3 weeks to potentiate the SCAD deficiency. We studied the urinary profiles of organic acids, acylglycines, hepatic and cerebral profiles of carnitines, and ammonia to assess the potentiation of this disorder. Cerebral activity of choline acetyltransferase (ChAT) was determined to study the effects of acyl-CoA accumulation on the cholinergic system. The results indicate that in riboflavin-deficient mutant mice, the excretion of ethylmalonate, methylsuccinate, butyrylglycine, and dicarboxylic acids was enhanced. Hepatic and cerebral free and esterified carnitines were reduced, indicating a potentiation of the secondary carnitine deficiency. Hepatic ammonia levels, but not cerebral ammonia or glutamine levels, were elevated, indicating a tendency towards secondary hyperammonemia. Brain choline acetyltransferase activity was significantly reduced in striatum, implying a reduced availability of cerebral acetyl-CoA or a decreased cerebral transport of choline: Most of these changes were partially or completely restored by a concomitant treatment with acetyl-L-carnitine (ALCAR). In summary, we conclude that BALB/cByJ mice with SCAD deficiency, but with a functional urea cycle, might have an adequate adaptive mechanism to adjust to an excessive acyl-CoA load without hyperammonemia at the cerebral level. However, any deficiency of vitamins or cofactors in the diet could disturb an adaptation to this disorder and produce an effect on the cholinergic system.

Metabolic studies in twin brothers with 2-methylacetoacetyl-CoA thiolase deficiency

We report clinical and biological investigations in two patients (twin brothers) with 2-methylacetoacetyl-CoA thiolase deficiency. Main clinical features included important staturo-ponderal delay, frequent infectious rhinopharyngitis episodes and an acute metabolic acidosis at the age of 4 years, this metabolic decompensation being adequately halted by bicarbonate supplementation. Since that age, patients developed rather favorably, however, with persistence of the staturo-ponderal delay. Organicaciduria typical of 2-methylacetoacetyl-CoA thiolase deficiency was recorded consisting of excessive excretion of tiglylglycine, 2-methyl-3-hydroxybutyrate, 3-hydroxyisovalerate, 2-methylglutaconate, adipate and 2-methylacetoacetate. Blood carnitine levels were altered in patients with increased total and esterified carnitine concentrations and enhanced acyl/free carnitine ratios. Determination of acylcarnitine profiles showed that patients excreted excessive amounts of several acylcarnitines in urine including propionyl, butyryl, isobutyryl, isovaleryl, 2-methylbutyryl and tiglyl-carnitine, the latter acylcarnitine being prominent with, in one of the patients, occurrence of a previously undescribed isomer of this carnitine ester, possibly 2-ethylacrylylcarnitine. Excretion of these acylcarnitines in urine was increased in response to l-carnitine although, as a whole, this therapy resulted in a less important stimulation of esterified carnitine removal in urine from patients than in the case of supplemented controls. Biochemical investigations on cultured skin fibroblasts confirmed 2-methylacetoacetyl-CoA thiolase deficiency. Through the present report on this rare disease in two siblings, we would like to underline that acylcarnitines can be used in the diagnosis of 2-methylacetoacetyl-CoA thiolase deficiency, a view supported by acylcarnitine profiles further determined in another patient with proven oxothiolase deficiency, adding this pathology to the list of β-oxidation disorders that may be screened successfully through determination of acylcarnitine profiles in body fluids.