Analysis of ACAT1 gene variants in a patient with β-ketothiolase deficiency / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology of a child suspected for β-ketothiolase deficiency by neonatal screening.@*METHODS@#All coding exons and flanking sequences of the ACAT1 gene were subjected to targeted capture and high-throughput sequencing. Suspected variants were verified by Sanger sequencing and bioinformatic analysis.@*RESULTS@#The child was found to harbor compound heterozygous variants of the ACAT1 gene, namely c.121-3C>G and c.275G>A (p. Gly92Asp). The c.121-3C>G variant was also detected in his father and two sisters, while the c.275G>A (p. Gly92Asp) was a de novo variant. A c.334+ 172C>G (rs12226047) polymorphism was also detected in his mother and two sisters. Sanger sequencing has verified that the c.275G>A (p. Gly92Asp) and c.334+172C>G (rs12226047) variants are located on the same chromosome. Bioinformatics analysis suggested both c.121-3C>G and c.275G>A (p.G92D) variants to be damaging. Based on the American College of Medical Genetics and Genomics standards and guidelines, the c.275G>A variant of the ACAT1 gene was predicted to be pathogenic (PS2+ PM2+ PM3+ PP3+PP4), the c.121-3C>G variant to be likely pathogenic (PM2+ PM3+ PP3+PP4).@*CONCLUSION@#The c.121-3C>G and c.275G>A variants of the ACAT1 gene probably underlay the pathogenesis of the child. Above finding has enriched the variant spectrum of the ACAT1 gene.

Nicorandil alleviated cardiac hypoxia/reoxygenation-induced cytotoxicity via upregulating ketone body metabolism and ACAT1 activity

To study the effect of nicorandil pretreatment on ketone body metabolism and Acetyl-CoA acetyltransferase (ACAT1) activity in hypoxia/reoxygenation (H/R)-induced cardiomyocytes. In our study, we applied H9c2 cardiomyocytes cell line to evaluate the cardioprotective effects of nicorandil. We detected mitochondrial viability, cellular apoptosis, reactive oxygen species (ROS) production and calcium overloading in H9c2 cells that exposed to H/R-induced cytotoxicity. Then we evaluated whether nicorandil possibly regulated ketone body, mainly β-hydroxybutyrate (BHB) and acetoacetate (ACAC), metabolism by regulating ACAT1 and Succinyl-CoA:3-keto-acid coenzyme A transferase 1 (OXCT1) protein and gene expressions. Nicorandil protected H9c2 cardiomyocytes against H/R-induced cytotoxicity dose-dependently by mitochondria-mediated anti-apoptosis pathway. Nicorandil significantly decreased cellular apoptotic rate and enhanced the ratio of Bcl-2/Bax expressions. Further, nicorandil decreased the production of ROS and alleviated calcium overloading in H/R-induced H9c2 cells. In crucial, nicorandil upregulated ACAT1 and OXCT1 protein expressions and either of their gene expressions, contributing to increased production of cellular BHB and ACAC. Nicorandil alleviated cardiomyocytes H/R-induced cytotoxicity through upregulating ACAT1/OXCT1 activity and ketone body metabolism, which might be a potential mechanism for emerging study of nicorandil and other K(ATP) channel openers.

Analysis of clinical phenotype and ACAT1 gene mutation in a family affected with beta-ketothiolase deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the clinical phenotype and ACAT1 gene mutation in a family affected with beta-ketothiolase deficiency (BKTD).</p><p><b>METHODS</b>Clinical features and laboratory test data were collected. The probands were monozygotic twin brothers. Genomic DNA was isolated from peripheral blood leukocytes obtained from the probands and their family members. Molecular genetic testing of the ACAT1 gene was carried out.</p><p><b>RESULTS</b>The probands have presented with fever, vomiting and severe ketoacidosis. By arterial blood gas testing, pH was determined to be 7.164, bicarbonate was 4.0 mmol/L, and urine ketone was ++++. Urinary organic acid gas chromatography-mass spectrometry analysis showed excessive excretion of 3-hydroxybutyric acid, 2-methyl-3-hydroxybutyric acid and tiglylglycine. Increased 3-hydroxybutyrylcarnitine (C4-OH), tiglylcarnitine(C5:1) and 3-hydroxyisovalerylcarnitine (C5-OH) levels. The clinical phenotype of proband's parents were both normal, but an elder sister turned out to be an affected patient. Genetic analysis has identified two heterozygous mutations [c.622C>T(p.R208X) and c.653C>T (p.S218F)] in the proband, which were respectively detected in the mother and father. The c.653C>T (p.S218F) mutation was not found among the 100 healthy controls and has not been included in the Human Gene Mutation Database(HGMD).</p><p><b>CONCLUSION</b>The primary clinical manifestations of BKTD is ketoacidosis. Urine organic acid and blood acylcarnitine analyses play an important role in the diagnosis of the disease. The compound heterozygous of ACAT1 gene mutations probably underlie the BKTD in our patient.</p>

Cloning and expression analysis of a acetyl-CoA U-acetyltransferase gene (TwAACT) from Tripterygium wilfordii / 中国中药杂志

In this study, based on the transcriptome data, we cloned the full-length cDNAs of TwAACT gene from Tripterygium wilfordii suspension cells, and then analyzed the bioinformation of the sequence, detected the genetic differential expression after being induced by methyl jasmonate (MeJA) by RT-PCR. The full-length cDNA of the TwAACT was 1 704 bp containing a 1 218 bp open reading frame (ORF) encoding a polypeptide of 405 amino acids (GeneBank accession No. KP297934). The deduced isoelectric point (pI) was 6.10, a calculated molecular weight was about 41.20 kDa, and online prediction showed that TwAACT had two catalytic active sites. After the induction of MeJA, the relative expression level of TwAACT increased rapidly. The expression level of TwAACT was highest at 24 h. TwAACT was cloned firstly, that laid the foundation for identifying thegene and illustrating thebiosynthesis mechanism and its synthetic biology.

Cloning and gene expression of acetyl-CoA C-acetyl transferase gene (AsAACT) from Aquilaria sinensis / 中国中药杂志

<p><b>OBJECTIVE</b>This study aimed to clone the acetyl-CoA C-acetyl transferase (AACT) gene from Aquilaria sinensis and analyze the bioinformatics and expression of the gene.</p><p><b>METHOD</b>One unique sequence containing partly AACT gene sequence was discovered in our previous transcriptome dataset of A. sinensis. AACT gene was cloned by RT-PCR and RACE strategy with the template of RNA extracted from A. sinensis stem. The bioinformatic analysis of this gene and its corresponding protein was performed. The AsAACT expression in calli was analyzed with GADPH gene as an internal control gene in wounded condition by qRT-PCR technique.</p><p><b>RESULT</b>One unique sequence of AACT, named as AsAACT, was cloned from A. sinensis. The full length of AsAACT cDNA was containing a 1 236 bp ORF that encoded 411 amino acids. The result of qRT-PCR displayed that the highest expression level was at 4 h. which indicated that it was possibly involved in early-stage response to wound.</p><p><b>CONCLUSION</b>Cloning and analyzing AsAACT gene from A. sinensis provided basic information for study the function and expression regulation of AsAACT in terpenoid biosynthesis.</p>

Normalization of the levels of inflammatory molecules in Mycobacterium smegmatis-infected U937 cells by fibrate pretreatment

BACKGROUND: Tuberculosis (TB) is a respiratory tract disease caused by Mycobacterium tuberculosis infection. M. tuberculosis exploits immune privilege to grow and divide in pleural macrophages. Fibrates are associated with the immune response and control lipid metabolism through glycolysis with ß-oxidation of fatty acids. RESULTS: In this study, we investigated the effect of fibrate pretreatment on the immune response during M. smegmatis infection in U937 cells, a human leukemic monocyte lymphoma cell line. The protein expression of tumor necrosis factor α (TNF-α), an inflammatory marker, and myeloid differentiation primary response gene 88 (MyD88), a toll like receptor adaptor molecule, in the infected group increased at 1 and 6 h after M. smegmatis infection of U937 cells. Acetyl coenzyme A acetyl transferase-1 (ACAT-1), peroxisome proliferator-activated receptor-α (PPAR-α), TNF-α, and MyD88 decreased in U937 cells treated with fibrates at 12 and 24 h after treatment. More than a 24 h pretreatment with fibrate resulted in similar expression levels of ACAT-1 and PPAR-α between infected vehicle control and infected groups which were pretreated with fibrate for 24 h. However, upon exposure to M. smegmatis, the cellular expression of the TNF-α and MyD88 in the infected groups pretreated with fibrate for 24 h decreased significantly compared to that in the infected vehicle group. CONCLUSION: These results suggest that fibrate pretreatment normalized the levels of inflammatory molecules in Mycobacterium smegmatis-infected U937 cells. Further studies are needed to confirm the findings on pathophysiology and immune defense mechanism of U937 by fibrates during M. tuberculosis infection.

Mutation analysis of a family with 2-Methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency / 中华儿科杂志

<p><b>OBJECTIVE</b>The aim of this study was to explore the genetic features of a family with 2-methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency (MHBDD) which may provide the basis for the diagnosis and genetic counseling.</p><p><b>METHOD</b>Clinical data of the proband was collected, total RNA and genomic DNA were extracted from the peripheral blood. The whole coding region of the ACAT1 gene was amplified by RT-PCR. 5' noncoding region of the ACAT1 gene and all 6 exons and flanking intron regions of the HADH2 gene were amplified by PCR. All amplification products were directly sequenced and compared with the reference sequence.</p><p><b>RESULT</b>(1) The patient was a one-year-old boy who presented with psychomotor retardation and astasia when he was admitted to the hospital. Biochemical test revealed slight hyperlactatemia (3.19 mmol/L) and magnetic resonance imaging showed delayed myelination. 2-Methylacetoacetyl-CoA thiolase deficiency was suggested by gas chromatography-mass spectrometry. (2) There was no mutation in the ACAT1 gene and a hemizygous missense mutation c.388C > T was found in the 4 exon of the HADH2 gene which resulted in p. R130C. Proband's mother was the heterozygote and the father was normal.</p><p><b>CONCLUSION</b>This is the first report on MHBDD patient and HADH2 mutation in China. p.R130C is responsible for the pathogenesis of the disease in the infant.</p>

Effects of rosiglitazone on cholesterol contents and scavenger receptor class B type I expression in RAW264.7 foam cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effect of rosiglitazone on the content of cholesterol and expressions of Acy-coenzyme A: cholesterol acyltransferase 1 (ACAT-1) and scavenger receptor class B type I (SR-BI) in RAW264.7 macrophage-derived foam cells and explore the anti-atherosclerotic mechanism of rosiglitazone.</p><p><b>METHODS</b>RAW264.7 macrophages were incubated with oxidized low-density lipoproteins (ox-LDL) or with both ox-LDL and rosiglitazone (5, 10, or 20 µmol/L). Oil red O staining was used to observe the formation of foam cells, and cholesterol oxidase was used to determine the content of cellular cholesterol contents. Western blotting was used observe the expressions of ACAT-1 and SR-BI in RAW264.7 foam cells.</p><p><b>RESULTS</b>Compared with the control cells, RAW264.7 macrophage-derived foam cells showed significantly increased contents of total cholesterol and free cholesterol (P<0.01) and ACAT-1 expressions (P<0.05) with mildly increased SR-BI expression (P>0.05). Rosiglitazone treatments significantly lowered the contents of total cholesterol and free cholesterol (P<0.05), decreased the expression of ACAT-1 (P<0.05), and increased SR-BI expression (P<0.05) in the foam cells in a dose-dependent manner.</p><p><b>CONCLUSION</b>Rosiglitazone can decrease the contents of total and free cholesterol, down-regulate ACAT-1 expression and up-regulate SR-BI expression in the foam cells produce the anti-atherosclerotic effect.</p>

Kinetic analysis of batch ethanol acetylation in isothermal non-stationary multiphase systems by lyophilized mycelium of Aspergillus oryzae

A relatively complex network of reactions has been investigated, using as a network model the isothermal batch esterification of acetic acid with ethanol in n-heptane catalyzed by lyophilized mycelium of Aspergillus oryzae. The kinetic analysis was firstly carried out on the whole system, without any simplification, by means of the well-known integral method. Owing to the poor results obtained by this way, we developed an alternative approach, combining initial rates and integral analysis and reducing the number of empirical parameters to be determined by the use of equilibrium data. All the values of the parameters calculated according to this "composite" approach to kinetic analysis well correlate with experimental data.

Leucodystrophy induced by late onset 3-hydroxy-3-methylglutaric aciduria / 中国当代儿科杂志

3-Hydroxy-3-methylglutaric aciduria is a rare disorder of organic acid metabolism caused by 3-hydroxy-3-methylglutaryl-coenzyme A lyase deficiency. The disorder was common in neonatal or infant period. Here a case of late onset 3-hydroxy-3-methylglutaric aciduria complicated by leucodystrophy was reported. The patient was a 7-year-old boy. He presented with progressive headache, drowsiness and vomiting. Hepatic lesions, ketosis and leucopenia were found. Symmetrical diffused leucodystrophy was shown by MRI. Blood levels of isovalerylcarnitine and acetylcarnitine increased significantly. Urinary levels of 3-hydroxy-3-methylglutaric, 3-methylglutaconic, 3-hydroxyglutaric acids and 3-methyl-crotonylglycine increased significantly. Symptoms were released by intravenous infusion of L-carnitine and glucose. After treatment for 6 months, urinary levels of 3-hydroxy-3-methylglutaric aciduria decreased in the boy and his health improved.

Molecular cloning and SNP analysis of a acetyl-CoA C-acetyltransferase gene (SmAACT) from Salvia miltiorrhiza / 药学学报

Acetyl-CoA C-acetyltransferase (AACT) is the first enzyme in the terpene synthesis pathway, catalyzed two units of acetyl-CoA to acetoacetyl-CoA. In order to study the tanshinone biosynthesis in Salvia miltiorrhiza, a novel AACT gene, SmAACT, was cloned using cDNA microarray and RACE strategy. The full length cDNA of SmAACT is 1 623 bp (accession No. EF635969), which contained a 1 200 bp open reading frame (ORF) encoding a 399 amino acid protein. Nine introns were found in the genomic sequence. SmAACT was upregulated by YE and Ag+ elicitors both with cDNA microarray and quantitative RT-PCR analyses along with the accumulation of tanshinones. Sequence homology comparison and phylogenetic analysis all suggested that SmAACT belonged to the class of acetyl-CoA C-acetyltransferase. The transcription level of SmAACT was relatively higher in root than that in stem and leaf tissues. SNP analysis revealed that SmAACT was highly variable in the region of 6 to 9 introns with 33 SNPs in the 600 bp region, there are 5 SNPs in the cDNA region while they are all synonymous cSNPs. Some special genotypes were found in Salvia miltiorrhiza from different areas. SmAACT will be an useful gene for further analyze the mechanism of gene regulation among the tanshinones biosynthesis.

Asymmetric dimethylarginine upregulates the expression of ACAT-1 in THP-1 macrophage-derived foam cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of asymmetric dimethylarginine (ADMA) on ACAT-1 expression and cholesterol content in THP-1-derived macrophages and foam cells.</p><p><b>METHODS</b>THP-1 cells were induced to differentiate into macrophages and further into foam cells. The macrophages and foam cells were exposed to different concentrations (0, 3.75, 7.5, 15, and 30 µmol/L) of ADMA for varying time lengths (6, 12, and 24 h), and the changes in ACAT-1 mRNA and protein levels in the cells were measured with RT-PCR and Western blotting. The cellular cholesterol content was measured with enzyme-linked colorimetry assay.</p><p><b>RESULTS</b>In THP-1-derived macrophages and foam cells, the expression levels of ACAT-1 mRNA and protein and cellular cholesterol content increased significantly in response to ADMA treatment in a time- and concentration-dependent manner.</p><p><b>CONCLUSION</b>ADMA may play an important role in inducing foam cell formation from macrophages. ACAT-1 inhibition targeting the macrophages and foam cells may serve as a potential therapeutic target in the treatment of atherosclerosis.</p>

PPARγ signal transduction pathway in the foam cell formation induced by visfatin / 生理学报

The aim of the present study was to investigate the role of peroxisome proliferator-activated receptor γ (PPARγ) signal transduction pathway in the expression of ATP binding cassette transporter A1 (ABCA1) and acyl-CoA:cholesterol acyltransferase 1 (ACAT1) induced by visfatin and to discuss the mechanism of foam cell formation induced by visfatin. THP-1 monocytes were induced into macrophages by 160 nmol/L phorbol myristate acetate (PMA) for 48 h, and then the macrophages were exposed to visfatin and PPARγ activator rosiglitazone, respectively. The expressions of PPARγ, ABCA1 and ACAT1 mRNA and protein were determined by RT-PCR and Western blot respectively. The contents of total cholesterol (TC) and free cholesterol (FC) were detected by enzyme fluorescence analysis. The content of cholesterol ester (CE) was calculated by the difference between TC and FC. The results showed that visfatin decreased the mRNA and protein expressions of PPARγ and ABCA1, increased the mRNA and protein expressions of ACAT1, and increased the contents of FC and CE in a concentration-dependent manner. These above effects of visfatin were inhibited by rosiglitazone in a concentration-dependent manner. These results suggest that visfatin may down-regulate the ABCA1 expression and up-regulate the ACAT1 expression via PPARγ signal transduction pathway, which decreases the outflow of FC, increases the content of CE, and then induces foam cell formation.

Engineering and metabolic characteristics of a Clostridium tyrobutyricum strain / 生物工程学报

Clostridium tyrobutyricum is suitable for simultaneous saccharification and fermentation of lignocellulosic. It can produce butyric acid, acetic acid as its main fermentation products from a wide variety of carbohydrates such as glucose, xylose, cellobiose and arabinose. In order to decrease acetic acid content and increase butyric acid content in C. tyrobutyricum, we replaced genes on the acetic acid fermentation pathway with genes on the butyric acid fermentation pathway. Three genes were selected. They were acetyl-CoA acetylrtansfers gene (thl) which is the key enzyme gene associated with acetic acid fermentation pathway from Clostridium acetobutylicum, erythromycin gene (em) from plasmid pIMP1 and phosphotransacetylase gene (pta) which is the key enzyme gene associated with butyric acid fermentation pathway from C. tyrobutyricum. We fused these genes with pUC19 to construct nonreplicative integrated plasmids pUC19-EPT. Then we transformed pUC19-EPT into C. tyrobutyricum through electroporation. The recombinant transformants grown on plates containing erythromycin were validated by PCR. A mutant whose pta gene was displaced by thl gene on the chromosome was selected. In the fermentation from glucose, the mutant's yield of butyric acid is 0.47, increased by 34% compared with wild type; and the yield of acetic acid is 0.05, decreased by 29% compared with wild type.

Ghrelin down-regulates ACAT-1 in THP-1 derived foam cells via growth hormone secretagogue receptor-dependent pathway / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effects of Ghrelin on the expression of acyl coenzyme A:cholesterol acyltransferases-1 (ACAT-1) in THP-1 derived foam cells.</p><p><b>METHODS</b>The human monocytic leukemia cell line (THP-1) was chosen in our study. The differentiation of THP-1 cells into macrophages was induced by phorbol 12-myristate 13-acetate. Macrophages were then incubated with oxidized LDL (ox-LDL) to generate foam cells. Ghrelin and [D-Lys3]-GHRP-6, the special antagonist of growth hormone secretagogue receptor (GHS-R), were treated during foam cells formation. The ACAT-1 protein and mRNA levels were detected by Western blot and RT-PCR. The effect of variance of cholesterol content was measured by zymochemistry via-fluorospectrophotometer.</p><p><b>RESULTS</b>Ghrelin reduced the content of cholesterol ester in foam cells obviously. ACAT-1 protein and mRNA levels were also decreased. The antagonist of GHS-R inhibited the effects of Ghrelin on ACAT-1 expression in dose-dependent manner. The ACAT-1 mRNA levels of the GHS-R specific antagonist groups (10(-5), 5 x 10(-5), 10(-4) mol/L) were 1.14 +/- 0.04, 1.58 +/- 0.03, 2.40 +/- 0.16, significantly higher than that of the Ghrelin group (0.89 +/- 0.05). And the protein expressions were 1.25 +/- 0.09, 1.77 +/- 0.11, 2.30 +/- 0.09, also higher than that of the Ghrelin group (0.86 +/- 0.08).</p><p><b>CONCLUSIONS</b>Ghrelin might interfere atherosclerosis by down-regulating the expression of ACAT-1 via GHS-R pathway.</p>

Inherited metabolic diseases in the urine organic acid analysis of complex febrile seizure patients / 소아과

PURPOSE: Seizure associated with fever may indicate the presence of underlying inherited metabolic diseases. The present study was performed to investigate the presence of underlying metabolic diseases in patients with complex febrile seizures, using analyses of urine organic acids. METHODS: We retrospectively analyzed and compared the results of urine organic acid analysis with routine laboratory findings in 278 patients referred for complex febrile seizure. RESULTS: Of 278 patients, 132 had no abnormal laboratory findings, and 146 patients had at least one of the following abnormal laboratory findings: acidosis (n=58), hyperammonemia (n=55), hypoglycemia (n=21), ketosis (n=12). Twenty-six (19.7%) of the 132 patients with no abnormal findings and 104 (71.2%) of the 146 patients with statistically significant abnormalities showed abnormalities on the organic acid analysis (P<0.05). Mitochondrial respiratory chain disorders (n=23) were the most common diseases found in the normal routine laboratory group, followed by PDH deficiency (n=2 ) and ketolytic defect (n=1). In the abnormal routine laboratory group, mitochondrial respiratory chain disorder (n=29) was the most common disease, followed by ketolytic defects (n=27), PDH deficiency (n=9), glutaric aciduria type II (n=9), 3-methylglutaconic aciduria type III (n=6), biotinidase deficiency (n=5), propionic acidemia (n=4), methylmalonic acidemia (n=2), 3-hydroxyisobutyric aciduria (n=2), orotic aciduria (n=2), fatty acid oxidation disorders (n=2), 2-methylbranched chain acyl CoA dehydrogenase deficiency (n=2), 3-methylglutaconic aciduria type I (n=1), maple syrup urine disease (n=1), isovaleric acidemia (n=1), HMG-CoA lyase deficiency (n=1), L-2-hydroxyglutaric aciduria (n=1), and pyruvate carboxylase deficiency (n=1). CONCLUSION: These findings suggest that urine organic acid analysis should be performed in all patients with complex febrile seizure and other risk factors for early detection of inherited metabolic diseases.

Biochemical profiling in two siblings with mitochondrial 2-methylacetoacetyl-CoA thiolase deficiency

We report the biochemical profiling in two siblings with mitochondrial 2-methylacetoacetyl-CoA thiolase deficiency. Organic aciduria typical of this rare inborn error metabolism was found when the elder sibling presented with an episode of severe ketoacidosis at 20 months of age, which consisted of excessive excretion of ketones, tiglylglycine, 2-methyl-3-hydroxybutyrate, and 2-methylacetoacetate. Blood acylcarnitiness profile showed elevation of C5OH-carnitine, which represents 2-methyl-3-hydroxybutyrylcarnitine. A similar biochemical profile was identified in the younger sibling during screening although he had only mild clinical symptoms. Both patients reported a favourable outcome on follow-up.

Deficiencia de la 2-metilacetoacetil-CoA tiolasa mitocondrial en Argentina / Mitochondrial 2-methylacetoacetyl-CoA thiolase deficiency in Argentina

A partir de la descripción de dos pares de hermanos, pertenecientes a familias no emparentadas, una argentina con antecedentes de consanguinidad y de ancestros irlandeses y la otra oriunda del Paraguay, en quienes se reconoció la deficiencia de la 2-metilacetoacetil-CoA tiolasa mitocondrial, comúnmente conocida como la deficiencia de la Beta-cetotiolasa (DCT; McKusick 203750; EC 2.3.1.9), intentamos delinear las consecuencias clínicas y bioquímicas de este defecto genético en el sexto paso del catabolismo de la isoleucina. La expresión fenotípica que presentaron los pacientes, correspondió a la forma clásica de DCT; el cuadro clínico uniforme se inició entre los 7 y 15 meses de edad y comprendió esencialmente, una asociación de uno o varios severos ataques cetoacidóticos e hiperglucemia constatada en dos de ellos. La demonstración por cromatografía en capa delgada de la tiglilglicina, dinitrofenilhidrazona de la butanona, aminoacidemia y aminoaciduria normales y un perfil único de ácidos orgánicos obtenido por cromatografía en fase gaseosa y espectrometría de masa (CG/EM) con excreción de grandes cantidades de los metabolitos característicos de la enfermedad, 2-metil-3-hidroxibutirato, 2-metil-acetato, tiglilglicina y 2-etilhidracrilato permitieron establecer el diagnóstico bioquímico de la DCT. El ensayo de la Beta-cetotiolasa en linfocitos y polimorfos nucleares de la única sobreviviente (VT), demostró una falta de activación por el ión K+ cuando se utilizó el acetoacetil-CoA como sustrato. Esta primera comunicación argentina sobre la DCT, permite inscribir tres aspectos ampliatorios respecto a las referencias previas: incorpora otros distintos orígenes étnicos de los pacientes, señala un análisis morfológico de material de autopsia sin cambios estructurales en cerebro, hígado y riñon y marca en la paciente VT, una disociación entre una clínica asintomática a partir de los 7 años y la persistente anormalidad bioquímica hasta la edad actual de 16 años. El conocimiento de la existencia de estas patologías en nuestro medio, aunado a la disponibilidad y acceso a la CG/EM de alta precisión y rapidez, permitirán reconocimientos precoces y mejores resultados terapéuticos.

Functional and biosynthetic aspects of sialic acid diversity.

Sialic acids comprise a large family of N- and O-substituted neuraminic acid derivatives as components of glycoconjugates. N-Glycolylneuraminic acid is formed from N-acetylneuraminic acid by the action of the CMP-N-acetylneuraminic acid hydroxylase studied in various animals. O-Methylated sialic acids originate from the action of S-adenosylmethionine-8-O-methyltransferase studied in starfish. Sialic acids are O-acetylated at diverse positions by the action of acetyl-CoA-4-O- and -7-O-acetyltransferases found in various animals and, leading to the O-acetylation of sialic acid glycerol side chain, also in man. Some properties of these enzymes are described and biological implications discussed.