Regulation of fatty acid transport protein and mitochondrial and peroxisomal beta-oxidation gene expression by fatty acids in developing rats

Regulation of genes involved in fatty acid (FA) utilization in heart and liver of weanling rats was investigated in response to variations in dietary lipid content and to changes in intracellular FA homeostasis induced by etomoxir, a blocker of FA import into mitochondria. Northern-blot analyses were performed using cDNA probes specific for FA transport protein, a cell membrane FA transporter; long-chain- and medium-chain acyl-CoA dehydrogenases, which catalyze the first step of mitochondrial FA beta-oxidation; and acyl-CoA oxidase, a peroxisomal FA beta-oxidation marker. High-fat feeding from postnatal d 21 to 28 resulted in a coordinate increase (58 to 136%) in mRNA abundance of all genes in heart. In liver, diet-induced changes in mitochondrial and peroxisomal beta-oxidation enzyme mRNAs (from 52 to 79%) occurred with no change in FA transport protein gene expression. In both tissues, the increases in mRNA levels went together with parallel increases in enzyme activity. Changes in FA homeostasis resulting from etomoxir administration led to a marked stimulation (76 to 180%) in cardiac expression of all genes together with parallel increases in enzyme activities. In the liver, in contrast, etomoxir stimulated the expression of acyl-CoA oxidase gene only. Feeding rats a low-fat diet containing 0.5% clofibrate, a ligand of peroxisome proliferator-activated receptor alpha, resulted in similar inductions of beta-oxidation enzyme genes in both tissues, whereas up-regulation of FA transport protein gene was restricted to heart. Altogether, these data suggest that changes in FA homeostasis in immature organs resulting either from high-fat diet or beta-oxidation blockade can efficiently be transduced to the level of gene expression, resulting in tissue-specific adaptations in various FA-using enzymes and proteins.     

Medium-chain acyl-CoA dehydrogenase deficiency in children with non-ketotic hypoglycemia and low carnitine levels

Three children in two families presented in early childhood with episodes of illness associated with fasting which resembled Reye's syndrome: coma, hypoglycemia, hyperammonemia, and fatty liver. One child died with cerebral edema during an episode. Clinical studies revealed an absence of ketosis on fasting (plasma beta-hydroxybutyrate less than 0.4 mmole/liter) despite elevated levels of free fatty acids (2.6-4.2 mmole/liter) which suggested that hepatic fatty acid oxidation was impaired. Urinary dicarboxylic acids were elevated during illness or fasting. Total carnitine levels were low in plasma (18-25 mumole/liter), liver (200-500 nmole/g), and muscle (500-800 nmole/g); however, treatment with L-carnitine failed to correct the defect in ketogenesis. Studies on ketone production from fatty acid substrates by liver tissue in vitro showed normal rates from short-chain fatty acids, but very low rates from all medium and long-chain fatty acid substrates. These results suggested that the defect was in the mid-portion of the intramitochondrial beta-oxidation pathway at the medium-chain acyl-CoA dehydrogenase step. A new assay for the electron transfer flavoprotein-linked acyl-CoA dehydrogenases was used to test this hypothesis. This assay follows the decrease in electron transfer flavoprotein fluorescence as it is reduced by acyl-CoA-acyl-CoA dehydrogenase complex. Results with octanoyl-CoA as substrate indicated that patients had less than 2.5% normal activity of medium-chain acyl-CoA dehydrogenase. The activities of short-chain and isovaleryl acyl-CoA dehydrogenases were normal; the activity of long-chain acyl-CoA dehydrogenase was one-third normal. These results define a previously unrecognized inherited metabolic disorder of fatty acid oxidation due to deficiency of medium-chain acyl-CoA dehydrogenase.     

Deficiency of long-chain 3-hydroxyacyl-CoA dehydrogenase: a cause of lethal myopathy and cardiomyopathy in early childhood

A child presented in early childhood with episodes of coma and hypoglycemia and a rapidly evolutive myopathy and cardiomyopathy leading to death at 9 mo of age. Ketosis was decreased (blood beta-hydroxybutyrate: 0.07 mmol/L) despite normal plasma levels of fatty acids (0.81 mmol/L). The patient's urine contained excessive amounts of the C6 to C10 dicarboxylic acids present in almost all defects of fatty acid mitochondrial oxidation. More specifically, gas chromatography-mass spectrometry identified an accumulation of medium- and long-chain (C8 to C14) 3-hydroxy-dicarboxylic acids, suggesting a defect of the mitochondrial enzyme that normally dehydrogenates these 3-hydroxyacyl-CoA esters. Biochemical studies in the patient's cultured fibroblasts confirmed the impairment of medium- and long-chain fatty acid oxidation, and allowed the recognition of the deficiency of long-chain 3-hydroxyacyl-CoA dehydrogenase. The activities of long-, medium-, and short-chain acyl-CoA dehydrogenases and 3-ketoacyl-CoA thiolase were normal. These results describe a disorder of fatty acid metabolism that affects the liver, skeletal muscles, and myocardium. It is important to point out that long-chain 3-hydroxyacyl-CoA deficiency shares many clinical similarities with systemic carnitine deficiency, as well as with carnitine-palmityl-CoA transferase and long-chain acyl-CoA dehydrogenase deficiencies. The differential diagnosis of this disease relies on the demonstration of long-chain urinary dicarboxylic acids with a hydroxyl group in 3-position and the study of the enzyme activity in cultured fibroblasts.     

Tissue carnitine homeostasis in very-long-chain acyl-CoA dehydrogenase-deficient mice

Deficiency of very-long-chain acyl-CoA dehydrogenase (VLCAD) is the most common long-chain fatty acid oxidation defect and presents with heterogeneous clinical manifestations. Accumulation of long-chain acylcarnitines and deficiency of free carnitine have often been proposed to play an important role in disease pathogenesis. The VLCAD-deficient mouse exhibits similar clinical and biochemical phenotypes to those observed in humans and, therefore, represents an excellent model to study VLCAD deficiency. We measured carnitine and acylcarnitine profiles in liver, skeletal muscle (SkM), bile, and blood from VLCAD knock-out mice and controls under nonstressed and various stress conditions. Carnitine and acylcarnitines were extracted from body fluids with methanol and from tissues with acetonitrile, respectively, and were analyzed as their butyl esters using electrospray ionization tandem mass spectrometry. Fasting combined with a cold challenge for 8 h significantly induced liver long-chain acylcarnitine and free carnitine production. Acylcarnitines in SkM predominantly accumulated during exercise with a concomitant decrease of free carnitine. Changes in blood free carnitine did not correlate with carnitine homeostasis in liver and SkM. Our results demonstrate different tissue-specific long-chain acylcarnitine profiles in response to various stressors, which may be of importance with respect to the heterogeneous clinical manifestations of VLCAD deficiency in humans. Furthermore, we conclude that carnitine biosynthesis in the liver seems sufficiently active to maintain liver carnitine levels during increased demand. Our data suggest that carnitine supplementation in long-chain beta-oxidation defects may not be required, and blood carnitine concentrations do not reflect tissue carnitine homeostasis.     

组蛋白乙酰化/去乙酰化失衡对平面细胞极性途径关键基因影响的研究

目的观察组蛋白乙酰化/去乙酰化失衡对胎鼠心脏的致畸作用及对H9C2心肌细胞平面细胞极性(PCP)途径关键基因Vangl2、Scrib、Rac1表达的影响。方法将40只C57/B6孕小鼠随机分为空白对照组(n=10)、溶剂对照组(n=10)和丙戊酸(VPA)组(n=20);应用组蛋白去乙酰化酶(HDAC)抑制剂VPA单次剂量700 mg/kg腹腔注射妊娠第10.5天(E10.5 d)VPA组孕鼠,溶剂对照组孕鼠腹腔注射等量生理盐水,空白对照组不做任何处理。于E15.5 d处死孕鼠,统计死胎率;取活胎鼠心脏行苏木精-伊红(HE)染色,观察VPA对胎鼠心脏的致畸作用。培养H9C2心肌细胞并将其分为空白对照组、溶剂对照组和VPA组,VPA组以不同浓度(2.0、4.0、8.0 mmol/L)作用于H9C2心肌细胞,溶剂对照组加入等量生理盐水,空白对照组不进行任何处理。实时荧光定量PCR和Western blot检测HDAC1~3及Vangl2、Scrib、Rac1基因在VPA干预后24、48、72 h mRNA及其蛋白表达水平;比色法测定总HDAC活性变化。结果 VPA组胎鼠死亡率为31.7%,心脏畸形发生率显著高于两对照组(P0.05)。与两对照组相比,不同浓度VPA干预后各时间点,HDAC1 mRNA表达水平均显著升高(P0.05),而蛋白表达水平于48 h及72 h显著降低(P0.05);不同浓度VPA干预后,HDAC2 mRNA仅在24 h表达显著下降(P0.05),而蛋白表达水平在各时间点均显著下调(P0.05);HDAC3 mRNA在VPA(4.0 mmol/L、8.0 mmol/L)干预的各时间点均表达增高(P0.05),而蛋白表达水平在不同浓度VPA干预后各时间点均下调(P0.05)。与两对照组相比,不同浓度VPA干预后,Vangl2、Scrib mRNA及其蛋白表达水平在48 h、72 h均显著下降(P0.05),Vangl2蛋白表达仅在72 h降低(P0.05)。与两对照组相比,VPA(4.0及8.0 mmol/L)干预后24 h,总HDAC活性显著降低(P0.05);干预后48 h、72 h,不同浓度VPA组总HDAC活性均明显降低(P0.05)。结论 VPA可能通过直接抑制HDAC1~3蛋白表达水平及总HDAC活性致乙酰化/去乙酰化失衡,从而导致PCP途径关键分子Vangl2、Scrib mRNA及蛋白表达水平下调,这可能是先天性心脏病发生的机制之一。     

Peroxisomal proliferation in heart and liver of mice receiving chlorpromazine, ethyl 2(5(4-chlorophenyl)pentyl) oxiran-2-carboxylic acid or high fat diet: a biochemical and morphometrical comparative study

Chlorpromazine and related drugs including trifluoperazine, clopenthixol, and fluphenazine are in vitro inhibitors of mitochondrial carnitine palmitoyltransferase and cytochrome c oxidase and of peroxisomal carnitine octanoyltransferase from mouse heart and liver. By contrast with 0.1% ethyl 2(5(4-chlorophenyl)pentyl) oxiran-2-carboxylic acid or 0.1% clofibrate-containing diets, the treatment of mice with 0.1% chlorpromazine-containing diet fails to induce peroxisomal proliferation in liver and heart. An 0.5% chlorpromazine-containing diet did induce peroxisomal proliferation. Inhibition of peroxisomal beta-oxidation presumably via the reduction of carnitine octanoyltransferase by chlorpromazine elicits the appearance in liver of lamellar structures resembling those seen in human peroxisomal disorders and induces accumulation of very long-chain fatty acids in plasma. The peroxisomal proliferation induced by administration of high dose chlorpromazine is ascribed to its ability to depress mitochondrial fatty acid oxidation by impairing cytochrome c oxidase and carnitine palmitoyltransferase activities.     

Long-chain acyl coenzyme A dehydrogenase deficiency: an inherited cause of nonketotic hypoglycemia

Three children from unrelated families presented in early childhood with hypoglycemia and cardiorespiratory arrests associated with fasting. Significant hepatomegaly, cardiomegaly, and hypotonia were present at the time of initial presentation. Ketones were not present in the urine at the time of hypoglycemia in any patient; however, dicarboxylic aciduria was documented in one patient at the time of the acute episode and in two patients during fasting studies. Total plasma carnitine concentration was low with an increased esterified carnitine fraction. These findings suggested a defect in mitochondrial fatty acid oxidation, and specific assays were performed for the acyl coenzyme A (CoA) dehydrogenases. These analyses showed that the activity of the long-chain acyl CoA dehydrogenase was less than 10% of control values in fibroblasts, leukocytes, and liver tissue. Activities of the medium-chain, short-chain, and isovaleryl CoA dehydrogenases were not different from control values. With cultured fibroblasts, CO2 evolution from long-chain fatty acids was significantly reduced, while CO2 evolution from medium-chain and short-chain fatty acids was comparable to control values--findings consistent with a defect early in the beta-oxidation sequence. Studies of acyl CoA dehydrogenase activities in fibroblasts and leukocytes from parents of the patients showed levels of long-chain acyl CoA dehydrogenase activity intermediate between affected and control values and indicated an autosomal recessive form of inheritance of this enzymatic defect.(ABSTRACT TRUNCATED AT 250 WORDS)     

儿童扩张性心肌病伴脂肪酸氧化代谢异常9例

目的:探讨儿童扩张性心肌病伴脂肪酸氧化代谢异常的临床特征、诊断与治疗。方法:回顾性分析2007年1月至2011年6月在首都医科大学附属北京安贞医院诊断为扩张性心肌病伴脂肪酸氧化代谢异常患儿的临床特征、实验室检查、治疗和随访情况。结果:9例扩张性心肌病伴脂肪酸氧化代谢异常患儿进入分析,男5例,女4例。病程0.5～4.5年,起病年龄11个月至18岁。9例均有乏力表现,4例合并肌肉无力,1例四肢近端肌萎缩,2例有惊厥发作,2例伴生长发育落后。9例均有不同程度肝肿大,8例肝功能异常,7例CK、CK-MB和乳酸脱氢酶增高,6例乳酸增高, 2例低血糖,3例高血氨。9例超声心动图检查均可见左心室舒张末期内径增高和射血分数下降。肌电图示肌源性损害2例。串联质谱检查示游离肉碱明显增高1例,减少5例,正常3例;酯酰肉碱增高7例,减少1例,正常1例。临床诊断肉毒碱棕榈酰转移酶Ⅰ缺乏症1例,原发性肉碱缺乏症1例,多种酰基辅酶A脱氢酶缺乏4例,长链酰基辅酶A脱氢酶缺乏3例。9例在常规抗心力衰竭治疗基础上,补充左旋肉碱、维生素及低脂肪、预防饥饿等饮食指导。随访0.5～3年,临床症状、生化指标和超声心动图表现逐渐改善。结论:原因不明的心脏扩大合并多系统症状和生化指标异常者,应考虑到脂肪酸代谢异常可能,及早进行代谢病筛查,早期诊断和合理治疗是改善预后的关键。     

Long-chain fatty acid oxidation during early human development

Patients with very long-chain acyl-CoA dehydrogenase (VLCAD) and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD)/mitochondrial trifunctional protein (MTP) deficiency, disorders of the mitochondrial long-chain fatty acid oxidation, can present with hypoketotic hypoglycemia, rhabdomyolysis, and cardiomyopathy. In addition, patients with LCHAD/MTP deficiency may suffer from retinopathy and peripheral neuropathy. Until recently, there was no indication of intrauterine morbidity in these disorders. This observation was in line with the widely accepted view that fatty acid oxidation (FAO) does not play a significant role during fetal life. However, the high incidence of the gestational complications acute fatty liver of pregnancy and hemolysis, elevated liver enzymes, and low platelets syndrome observed in mothers carrying a LCHAD/MTP-deficient child and the recent reports of fetal hydrops due to cardiomyopathy in MTP deficiency, as well as the high incidence of intrauterine growth retardation in children with LCHAD/MTP deficiency, suggest that FAO may play an important role during fetal development. In this study, using in situ hybridization of the VLCAD and the LCHAD mRNA, we report on the expression of genes involved in the mitochondrial oxidation of long-chain fatty acids during early human development. Furthermore, we measured the enzymatic activity of the VLCAD, LCHAD, and carnitine palmitoyl-CoA transferase 2 (CPT2) enzymes in different human fetal tissues. Human embryos (at d 35 and 49 of development) and separate tissues (5-20 wk of development) were used. The results show a strong expression of VLCAD and LCHAD mRNA and a high enzymatic activity of VLCAD, LCHAD, and CPT2 in a number of tissues, such as liver and heart. In addition, high expression of LCHAD mRNA was observed in the neural retina and CNS. The observed pattern of expression during early human development is well in line with the spectrum of clinical signs and symptoms reported in patients with VLCAD or LCHAD/MTP deficiency.     

Carnitine content and expression of mitochondrial beta-oxidation enzymes in placentas of wild-type (OCTN2(+/+)) and OCTN2 Null (OCTN2(-/-)) Mice

Placenta requires energy to support its rapid growth, maturation, and transport function. Fatty acids are used as energy substrates in placenta, but little is known about the role played by carnitine in this process. We have investigated the role of carnitine in the expression of the enzymes involved in fatty acid beta-oxidation in placenta of OCTN2(-/-) mice with defective carnitine transporter (OCTN2). Heterozygous (OCTN2(+/-)) female mice were mated with heterozygous (OCTN2(+/-)) male mice. Pregnant mice were killed and fetuses and placentas were collected. Carnitine was measured using HPLC and tandem mass spectrometry. Immunohistochemistry was used to detect enzyme expression. Enzyme activities were measured spectrophotometrically. The fetal and placental weights were similar among the three genotypes (OCTN2(+/+), OCTN2(+/-), and OCTN2(-/-)). The levels of carnitine were markedly reduced (<20%) in homozygous OCTN2(-/-) null fetuses and placentas compared with wild-type OCTN2(+/+) controls. However, carnitine concentration in placenta was 2- to 7-fold higher than in the fetus in all three genotypes. Immunohistochemistry revealed that beta-oxidation enzymes are expressed in trophoblast cells. Catalytic activities of these enzymes were present at comparable levels in wild-type (OCTN2(+/+)) and homozygous (OCTN2(-/-)) mouse placentas, with the exception of SCHAD, for which activity was significantly higher in OCTN2(-/-) placentas than in OCTN2(+/+) placentas. These data show that placental OCTN2 is obligatory for accumulation of carnitine in placenta and fetus, that fatty acid beta-oxidation enzymes are expressed in placenta, and that reduced carnitine levels up-regulate the expression of SCHAD in placenta.     

Nonalcoholic fatty liver disease during valproate therapy

Valproic acid (VPA) is effective for the treatment of many types of epilepsy, but its use can be associated with an increase in body weight. We report a case of nonalcoholic fatty liver disease (NAFLD) arising in a child who developed obesity during VPA treatment. Laboratory data revealed hyperinsulinemia with insulin resistance. After the withdrawal of VPA therapy, our patient showed a significant weight loss, a decrease of body mass index, and normalization of metabolic and endocrine parameters; moreover, ultrasound measurements showed a complete normalization. The present case suggests that obesity, hyperinsulinemia, insulin resistance, and long-term treatment with VPA may be all associated with the development of NAFLD; this side effect is reversible after VPA withdrawal.     

Mitochondrial fatty acid beta-oxidation in the retinal pigment epithelium

Pigmentary retinopathy is an important feature of long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency, a disorder of mitochondrial fatty acid beta-oxidation. Pathogenesis of this complication remains unknown. The retinal pigment epithelium (RPE) is affected early in this retinopathy. We wanted to determine whether there is evidence of mitochondrial fatty acid beta-oxidation in the RPE cells. Fatty acid oxidation was measured from cultured porcine RPE cells by incubating them with [U-13C]-hexadecanoic acid. Acylcarnitine esters were analyzed by tandem mass spectrometry. The activity of LCHAD and carnitine uptake capacity were measured from the cultured cells. Antibodies to the human mitochondrial trifunctional protein (MTP) containing LCHAD activity were used to analyze the expression of the MTP in the cultured RPE cell lysate and in human retinal sections by immunoblotting and immunohistochemistry. Fatty acid oxidation analysis showed normal chain shortening of hexadecanoic acid and production of acetylcarnitine in cultured RPE cells. Immunoblotting revealed expression of the MTP and enzyme assay showed the activity of LCHAD in the RPE cells. RPE cells were also capable of carnitine uptake. Positive labeling to the MTP antibodies was detected in the RPE, photoreceptors, and ganglion cells. The results give strong in vitro evidence for the presence of mitochondrial fatty acid beta-oxidation in RPE cells and the expression of the MTP in the RPE and other layers of the retina. Further studies are required to clarify whether this pathway acts also in vivo in the retina.     

Acyl-CoA dehydrogenase enzymes during early postnatal development in the rat

Fatty acid oxidation rates tend to increase with age in most developing tissues. In skeletal muscle, heart, and liver of developing rats, we measured activities of three acyl-CoA dehydrogenase enzymes, which constitute the first step in the mitochondrial beta-oxidation sequence. In skeletal muscle, activities of all three enzymes increased with age. In heart muscle, palmityl-CoA dehydrogenase increased, while the other two enzymes changed only minimally. In liver, palmityl-CoA dehydrogenase activity steadily increased with age. Decanoyl- and butyryl-CoA dehydrogenase also increased with age, but much more irregularly. We also examined the electrophoretic characteristics of these enzyme proteins in the three tissues. There were no changes in their electrophoretic patterns during development.     

脂肪酸氧化代谢病与心肌病

脂肪酸是心肌最重要的能量来源, 脂肪酸氧化代谢病（FAOD）可导致线粒体能量生成不足, 同时可造成心肌细胞内脂质和长链酰基肉碱等中间代谢产物蓄积, 从而导致心肌病变。FAOD主要包括肉碱依赖的脂肪酸转运障碍和线粒体内的脂肪酸β-氧化异常, 缺陷可发生于脂肪酸氧化过程中的任何酶或转运蛋白。尽管FAOD是引起儿童心肌病的少见病因之一, 但部分FAOD通过早期纠正脂肪酸代谢紊乱后, 心肌病有望得到改善, 生存质量可显著提高。     

Early diagnosis and treatment of neonatal medium-chain acyl-CoA dehydrogenase deficiency: Report of two siblings

Two siblings are reported who were syptomatic in the neonatal period. The first died suddenly at 4 days of age after regurgitating a meal. The postmortem examination showed steatosis of the liver, kidney and muscle. In the second, medium-chain acyl-CoA dehydrogenase (MCAD) deficiency was diagnosed at 3 days of age with muscular hypotonia, vomiting, hyperammonaemia and mild acidosis. Thus disorders of fatty acid oxidation should also be considered in newborns. The biochemical work up indicates that in neonates, analysis of serum medium-chain fatty acids and of acyl and free carnitine are more likely to lead to a diagnosis than determining dicarboxylic acids alone in urine. Long-term treatment was effective and monitored by the acyl/free carnitine ratio.An abstract relating the initial findings of this patient was published by Catzeflis C, Délèze G, Kuchler H, Spahr A, Schütz B, Bachmann C (1987) Helv Paediatr Acta 42:47     

Carnitine metabolism in valproate-treated rats: the effect of L-carnitine supplementation

The effect of the administration for 7 days of valproate (500 mg/kg/day) or valproate (500 mg/kg/day) plus L-carnitine (200 mg/kg/day) on carnitine concentrations in serum, red blood cells, muscle, liver, and urine was evaluated. In the serum and muscle of the valproic acid (VPA) group, free carnitine levels decreased, while acyl-carnitine levels and acyl/free ratio increased, when compared to those of the control. When L-carnitine was given to the VPA group, the free carnitine levels increased in the serum, muscle, and liver, and the acyl/free ratio decreased in all tissues when compared to those of the VPA group. The mean of free carnitine level in urine of the VPA group was not different but acylcarnitine increased when compared to values of controls, and after the supplementation with L-carnitine the acylcarnitine (from day 4 to 7) levels were decreased compared to the VPA group. The serum beta-OH-butyrate level in the VPA group was decreased when compared to those of controls and VPA plus L-carnitine groups. These results indicate that L-carnitine supplementation protects against the alteration in carnitine metabolism induced by the administration of VPA.     

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??Objective??To systematically review the effectiveness and safety of carnitine for patients with epilepsy using valproic acid??VPA??. Methods??The clinical trials about carnitine for patients with epilepsy using VPA were searched in PubMed??Cochrane Library??EMbase??CBM??CNKI??Wanfang Data and VIP from the date of their establishment to March 2017.Literature screening and methodological quality assessment were completed by two reviewers independently. Meta-analysis was conducted using RevMan 5.3 software. Results??A total of ten trials involving 206 patients were finally enrolled. The results of meta-analysis indicated that????1??the carnitine for epileptic children who were intoxicated with VPA could decrease concentration of ALT and AST??ALT??MD??-63.97??95%CI??-64.98??-62.96????P??0.00001??AST??MD??-55.14??95%CI??-56.52??-53.76????P??0.00001?? .??2??Carnitine for epileptic children who had high risk factors of liver injury using VPA could decrease concentration of ALT and AST??ALT??MD??-12.53??95%CI??-15.32??-9.75????P??0.00001??AST??MD??-19.45??95%CI??-36.50??-2.40????P??0.03??. Conclusion??Current evidence suggests that carnitine improves the liver function indicators with fewer adverse reactions and decreases concentration of ammonia??and improves the life quality of patients. However??due to the limited quantity and quality of the included studies??more multicenter high quality RCTs with large sample size are needed to verify the above conclusion.     

Altered expression and function of mitochondrial beta-oxidation enzymes in juvenile intrauterine-growth-retarded rat skeletal muscle.

Uteroplacental insufficiency and subsequent intrauterine growth retardation (IUGR) affects postnatal metabolism. In juvenile rats, IUGR alters skeletal muscle mitochondrial gene expression and reduces mitochondrial NAD(+)/NADH ratios, both of which affect beta-oxidation flux. We therefore hypothesized that gene expression and function of mitochondrial beta-oxidation enzymes would be altered in juvenile IUGR skeletal muscle. To test this hypothesis, mRNA levels of five key mitochondrial enzymes (carnitine palmitoyltransferase I, trifunctional protein of beta-oxidation, uncoupling protein-3, isocitrate dehydrogenase, and mitochondrial malate dehydrogenase) and intramuscular triglycerides were quantified in 21-d-old (preweaning) IUGR and control rat skeletal muscle. In isolated skeletal muscle mitochondria, enzyme function of the trifunctional protein of beta-oxidation and isocitrate dehydrogenase were measured because both enzymes compete for mitochondrial NAD(+). Carnitine palmitoyltransferase I, the trifunctional protein of beta-oxidation, and uncoupling protein 3 mRNA levels were significantly increased in IUGR skeletal muscle, whereas mRNA levels of isocitrate dehydrogenase and mitochondrial malate dehydrogenase were unchanged. Similarly, trifunctional protein of beta-oxidation activity was increased in IUGR skeletal muscle mitochondria, and isocitrate dehydrogenase activity was unchanged. Interestingly, skeletal muscle triglycerides were significantly increased in IUGR skeletal muscle. We conclude that uteroplacental insufficiency alters IUGR skeletal muscle mitochondrial lipid metabolism, and we speculate that the changes observed in this study play a role in the long-term morbidity associated with IUGR.     

3-Hydroxydicarboxylic aciduria--a fatty acid oxidation defect with severe prognosis

We describe five patients with a suspected defect in the beta-oxidation of fatty acids characterized by a massive excretion of 3-hydroxydicarboxylic acids in the urine and accumulation of 3-hydroxy fatty acids in serum during acute illness. Long-chain and medium-chain acyl-coenzyme A dehydrogenases in fibroblasts were normal in all patients. Four of them died of cardiomyopathy and liver insufficiency at 3 to 14 months of age. Two of the patients had elder siblings who had died unexpectedly in early infancy. These patients differ from previously described patients with beta-oxidation defects.     

Increase of fetal hemoglobin synthesis indicating differentiation induction in children receiving valproic acid

Differentiation induction is a distinct concept in the treatment of malignant diseases, considering that malignant cells share many features with immature progenitor cells that are capable of terminal differentiation. Treatment of tumor cells with short-chain fatty acids leads to cytostasis and differentiation induction both in vitro and in vivo. Similarly, short-chain fatty acid treatment of erythroid progenitors in vitro and in vivo induces cellular differentiation resulting in γ-globin, i.e., fetal hemoglobin synthesis. Valproic acid (VPA) is a branched-chain fatty acid that is able to inhibit growth of human and rodent tumor cells and to induce a mature phenotype. The antitumoral effects observed in preclinical studies were reached at concentrations that are readily achieved in patients treated with VPA for epilepsy. Hypothesizing that anticonvulsive VPA levels may be used for antitumoral differentiation induction therapy of pediatric malignant tumors, the authors studied fetal hemoglobin-inducing capacity of VPA in children treated with VPA for epilepsy. Fetal hemoglobin was significantly increased in 30 children with epilepsy treated with VPA monotherapy for at least 3 months when compared to untreated control patients. Furthermore, fetal hemoglobin levels correlated with VPA serum levels. The study confirms the dose-dependent stimulating effect of VPA on fetal hemoglobin synthesis at anticonvulsive doses. The results suggest that nontoxic VPA levels reached in pediatric epilepsy patients should be capable of inducing cellular differentiation of pediatric malignant tumors for therapeutic purposes. Broad clinical experience with VPA and its low toxicity further encourage the evaluation of VPA in pediatric oncology for differentiation induction therapy.