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Biomedical subjects

Marzia Pasquali

Publications and source records attributed to Marzia Pasquali.

16 recordsLinked to original sources
PubMed2007

Asymmetric dimethylarginine, cortisol/cortisone ratio, and C-peptide: markers for diabetes and cardiovascular risk?

BACKGROUND: Diabetes and prediabetic conditions are growing cardiovascular risk factors. Better understanding and earlier recognition and treatment of dysglycemia-related risk are health priorities. We assessed the predictive value of 3 proposed new markers for diabetes and cardiovascular risk. We tested whether the plasma levels of (1) asymmetric dimethylarginine (ADMA), (2) cortisol/cortisone (Cl/Cn) ratio, and (3) C-peptide predicted glycemic status, coronary artery disease, and death or myocardial infarction (MI) in a nested case-control cohort (N = 850) with normal fasting glucose (< 110 mg/dL), impaired fasting glucose (110-125), or diabetic (> or = 126) status. METHODS: High-sensitivity C-reactive protein (hsCRP) served as a control risk marker. Follow-up averaged 2.6 +/- 1.4 years. High-pressure liquid chromatography with pre-column derivitization and fluorescence was used to assay ADMA, liquid chromatography/tandem mass spectrometry for Cl and Cn, and chemiluminescent immunoassay for C-peptide. RESULTS: Asymmetric dimethylarginine levels were positively associated with glycemic category (P < .001). Quartiles 2 to 4 ADMA also conferred increased risk of death/MI independent of hsCRP and other risk factors (adjusted hazard ratio, 2.1; P = .002). Cortisol/Cortisone ratios (P = .013) and C-peptide (P = .047) were associated with glycemic categories but less strongly than ADMA. Quartiles 2 to 4 Cl/Cn were protective against incident death/MI (adjusted hazard ratio, 0.48; P < .001), whereas C-peptide did not predict outcomes. CONCLUSIONS: Among a high coronary risk case-control cohort, ADMA (strongly), Cl/Cn (moderately), and C-peptide (weakly) predicted glycemic categories. Asymmetric dimethylarginine and Cl/Cn also predicted clinical outcome independent of and more strongly than hsCRP. Asymmetric dimethylarginine and Cl/Cn represent promising new candidate markers of dysglycemia and associated cardiovascular risk.

Arginine↗
PubMed2006

Expanded newborn screening identifies maternal primary carnitine deficiency.

Primary carnitine deficiency impairs fatty acid oxidation and can result in hypoglycemia, hepatic encephalopathy, cardiomyopathy and sudden death. We diagnosed primary carnitine deficiency in six unrelated women whose unaffected infants were identified with low free carnitine levels (C0) by newborn screening using tandem mass spectrometry. Given the lifetime risk of morbidity or sudden death, identification of adult patients with primary carnitine deficiency is an added benefit of expanded newborn screening programs.

Adult↗
PubMed2006

Biochemical findings in common inborn errors of metabolism.

The application of tandem mass spectrometry (MS/MS) to newborn screening has led to the detection of patients with a wider spectrum of inborn errors of metabolism. A definitive diagnosis can often be established early enough to start treatment before symptoms appear. Here, we review common biochemical findings in disorders caused by deficiency of 3-methylcrotonyl-CoA carboxylase, isobutyryl-CoA dehydrogenase, 2-methyl-3-hydroxybutyryl-CoA dehydrogenase, 3-ketothiolase, 2-methylbutyryl-CoA dehydrogenase, and medium chain acyl CoA dehydrogenase. The diagnosis of these disorders requires biochemical confirmation by measurement of plasma acylcarnitine profile, urine organic acids, and urine acylglycine profiles followed by measurement of enzyme activity or detection of causative mutations. Early treatment can improve the outcome of these disorders.

Blood Chemical Analysis↗
PubMed2006

Disorders of carnitine transport and the carnitine cycle.

Carnitine plays an essential role in the transfer of long-chain fatty acids across the inner mitochondrial membrane. This transfer requires enzymes and transporters that accumulate carnitine within the cell (OCTN2 carnitine transporter), conjugate it with long chain fatty acids (carnitine palmitoyl transferase 1, CPT1), transfer the acylcarnitine across the inner plasma membrane (carnitine-acylcarnitine translocase, CACT), and conjugate the fatty acid back to Coenzyme A for subsequent beta oxidation (carnitine palmitoyl transferase 2, CPT2). Deficiency of the OCTN2 carnitine transporter causes primary carnitine deficiency, characterized by increased losses of carnitine in the urine and decreased carnitine accumulation in tissues. Patients can present with hypoketotic hypoglycemia and hepatic encephalopathy, or with skeletal and cardiac myopathy. This disease responds to carnitine supplementation. Defects in the liver isoform of CPT1 present with recurrent attacks of fasting hypoketotic hypoglycemia. The heart and the muscle, which express a genetically distinct form of CPT1, are usually unaffected. These patients can have elevated levels of plasma carnitine. CACT deficiency presents in most cases in the neonatal period with hypoglycemia, hyperammonemia, and cardiomyopathy with arrhythmia leading to cardiac arrest. Plasma carnitine levels are extremely low. Deficiency of CPT2 present more frequently in adults with rhabdomyolysis triggered by prolonged exercise. More severe variants of CPT2 deficiency present in the neonatal period similarly to CACT deficiency associated or not with multiple congenital anomalies. Treatment for deficiency of CPT1, CPT2, and CACT consists in a low-fat diet supplemented with medium chain triglycerides that can be metabolized by mitochondria independently from carnitine, carnitine supplements, and avoidance of fasting and sustained exercise.

Animals↗
PubMed2006

Glutaric acidemia type 1.

Glutaric acidemias comprise different disorders resulting in an increased urinary excretion of glutaric acid. Glutaric acidemia type 1 (GA-1) is an autosomal recessive disorder of lysine, hydroxylysine, and tryptophan metabolism caused by deficiency of glutaryl-CoA dehydrogenase. It results in the accumulation of 3-hydroxyglutaric and glutaric acid. Affected patients can present with brain atrophy and macrocephaly and with acute dystonia secondary to striatal degeneration in most cases triggered by an intercurrent childhood infection with fever between 6 and 18 months of age. This disorder can be identified by increased glutaryl (C5DC) carnitine on newborn screening. Urine organic acid analysis indicates the presence of excess 3-OH-glutaric acid, and urine acylcarnitine profile shows glutaryl carnitine as the major peak. Therapy consists in carnitine supplementation to remove glutaric acid, a diet restricted in amino acids capable of producing glutaric acid, and prompt treatment of intercurrent illnesses. Early diagnosis and therapy reduce the risk of acute dystonia in patients with GA-1.

Amino Acid Metabolism, Inborn Errors↗
PubMed2006

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.

Amino Acid Metabolism, Inborn Errors↗
PubMed2006

Pharmacological rescue of carnitine transport in primary carnitine deficiency.

Primary carnitine deficiency is a recessive disorder caused by heterogeneous mutations in the SLC22A5 gene encoding the OCTN2 carnitine transporter. Here we extend mutational analysis to eight new families with this disorder. To determine the mechanism by which missense mutations impaired carnitine transport, the OCTN2 transporter was tagged with the green fluorescent protein and expressed in CHO cells. Analysis by confocal microscopy indicated that several missense mutants (M1I, R169W, T232 M, G242 V, S280F, R282Q, W283R, A301D, W351R, R399Q, T440 M, E452 K, and T468R) matured normally to the plasma membrane. By contrast, other mutations (including R19P, DeltaF22, R83L, S280F, P398L, Y447C, and A142S/R488 H) caused significant retention of the mutant OCTN2 transporter in the cytoplasm. Failed maturation to the plasma membrane is a common mechanism in disorders affecting membrane transporters/ion channels, including cystic fibrosis. To correct this defect, we tested whether drugs reducing the efficiency of protein degradation in the endoplasmic reticulum (ER) (phenylbutyrate, curcumin) or capable of binding the OCTN2 carnitine transporter (verapamil, quinidine) could improve carnitine transport. Prolonged incubation with phenylbutyrate, quinidine, and verapamil partially stimulated carnitine transport, while curcumin was ineffective. These results indicate that OCTN2 mutations can affect carnitine transport by impairing maturation of transporters to the plasma membrane. Pharmacological therapy can be effective in partially restoring activity of mutant transporters.

Adult↗
PubMed2006

Teaching pediatric laboratory medicine to pathology residents.

CONTEXT: Laboratory data are essential to the medical care of fetuses, infants, children, and adolescents. However, the performance and interpretation of laboratory tests on specimens from these patients, which may constitute a significant component of the workload in general hospitals and integrated health care systems as well as specialized perinatal or pediatric centers, present unique challenges to the clinical pathologist and the laboratory. Therefore, pathology residents should receive training in pediatric laboratory medicine. OBJECTIVE: Children's Health Improvement through Laboratory Diagnostics, a group of pathologists and laboratory scientists with interest and expertise in pediatric laboratory medicine, convened a task force to develop a list of curriculum topics, key resources, and training experiences in pediatric laboratory medicine for trainees in anatomic and clinical pathology or straight clinical pathology residency programs and in pediatric pathology fellowship programs. DATA SOURCES: Based on the experiences of 11 training programs, we have compiled a comprehensive list of pediatric topics in the areas of clinical chemistry, endocrinology, hematology, urinalysis, coagulation medicine, transfusion medicine, immunology, microbiology and virology, biochemical genetics, cytogenetics and molecular diagnostics, point of care testing, and laboratory management. This report also includes recommendations for training experiences and a list of key texts and other resources in pediatric laboratory medicine. CONCLUSIONS: Clinical pathologists should be trained to meet the laboratory medicine needs of pediatric patients and to assist the clinicians caring for these patients with the selection and interpretation of laboratory studies. This review helps program directors tailor their curricula to more effectively provide this training.

Child↗
PubMed2005

Acidified acetonitrile and methanol extractions for quantitative analysis of acylcarnitines in plasma by stable isotope dilution tandem mass spectrometry.

We have compared two sample preparation methods for the analysis of plasma acylcarnitines by tandem mass spectrometry. Extraction from liquid plasma using acetonitrile was compared with the widely used methanol extraction from plasma spotted on filter paper. The recovery and reproducibility of the acetonitrile extraction were improved by acidification with 0.3% formic acid. The acidified acetonitrile and methanol extractions have the same limit of detection and upper linearity limit for all acylcarnitine species studied. The correlation coefficients between the two methods were greater than 0.988 and the slopes of the linear regressions ranged from 0.901 to 1.070. The extraction of acylcarnitines by acidified acetonitrile from liquid plasma yielded results comparable to those obtained by methanol extraction from plasma spotted on filter paper.

Acetonitriles↗
PubMed2004

Analysis of plasma amino acids by HPLC with photodiode array and fluorescence detection.

BACKGROUND: Plasma amino acids are usually analyzed by ion-exchange chromatography (IEC), a reproducible but time consuming method. Here, we test whether plasma amino acids can be analyzed using reverse-phase high performance liquid chromatography (HPLC). METHODS: Filtered plasma, with S-carboxymethyl-l-cysteine as the internal standard, was derivatized and analyzed by an Agilent 1100 HPLC system. Primary amino acids were derivatized with o-phthalaldehyde 3-mercaptopropionic acid (OPA) and detected by a diode array detector. Secondary amino acids were derivatized with 9-fluorenylmethyl chloroformate (FMOC) and detected fluorometrically. Chromatographic separation is achieved by two gradient elutions (two injections per sample), starting at different pHs, on a reverse phase Agilent Zorbax Eclipse C(18) column AAA (4.6 x 150 mm). RESULTS: The HPLC method evaluated correlated well with IEC (0.89</=r</=1.00) with linearity up to 2500 mumol/l. The between- and within-run CVs were <6.0%. In addition, this method is able to separate argininosuccinic acid, homocystine and allo-isoleucine, rare but clinically significant amino acids. CONCLUSION: This HPLC method was comparable to IEC and could represent an alternative for amino acid analysis.

Amino Acids↗
PubMed2004

Interaction between altered insulin and lipid metabolism in CEACAM1-inactive transgenic mice.

Inactivation of CEACAM1 in L-SACC1 mice by a dominant-negative transgene in liver impairs insulin clearance and increases serum free fatty acid (FFA) levels, resulting in insulin resistance. The contribution of elevated FFAs in the pathogenesis of insulin resistance is herein investigated. Treatment of L-SACC1 female mice with carnitine restored plasma FFA content. Concomitantly, it normalized insulin levels without directly regulating receptor-mediated insulin internalization and prevented glucose tolerance in these mice. Similarly, treatment with nicotinic acid, a lipolysis inhibitor, restored insulin-stimulated receptor uptake in L-SACC1 mice. Taken together, these data suggest that chronic elevation in plasma FFAs levels contributes to the regulation of insulin metabolism and action in L-SACC1 mice.

3-Hydroxybutyric Acid↗
PubMed2004

Solid phase extraction procedure for urinary organic acid analysis by gas chromatography mass spectrometry.

We have developed a solid phase extraction procedure for the detection of organic acids by GC-MS using a strong anion exchange column (Sep-Pak Vac RC, Accell Plus QMA cartridge). Extraction efficiencies of 25 organic acids were established by analyzing standards in water based solutions. High extraction efficiencies (90 to 100%) were found for many of the compounds studied. We estimated the limit of detection for 48 organic acids and glycine conjugates. They were below 5 nmole with the exception of malonic and oxalic acids and mevalonic acid lactone. This method provides the advantage of higher recoveries for a wide range of compounds of interest and therefore can be a potential alternative to liquid-liquid extraction for organic acid screening. It is especially sensitive for the detection of some polar compounds, such as 3-OH-glutaric and N-acetylaspartic acids.

Acids↗
PubMed2004

Response to therapy in carnitine/acylcarnitine translocase (CACT) deficiency due to a novel missense mutation.

Deficiency of carnitine/acylcarnitine translocase (CACT) is an autosomal recessive disorder of the carnitine cycle resulting in the inability to transfer fatty acids across the inner mitochondrial membrane. Only a limited number of affected patients have been reported and the effect of therapy on this condition is still not well defined. Here, we report a new patient with this disorder and follow the response to therapy. Our patient was the product of a consanguineous marriage. He presented shortly after birth with cardiac myopathy and arrhythmia coupled with severe non-ketotic hypoglycemia. Initial metabolic studies indicated severe non-ketotic C6-C10 dicarboxylic aciduria, plasma carnitine deficiency, and a characteristic elevation of plasma C:16:0, C18:1, and C18:2 acylcarnitine species. Enzyme assay confirmed deficiency of CACT activity. Molecular studies indicated that this child was homozygous, and both parents heterozygous, for a single bp change converting glutamine 238 to arginine (Q238R). Therapy with a formula providing most of the fat via medium chain triglycerides (MCT) and carnitine supplementation reduced the concentration of long-chain acylcarnitines and reversed cardiac symptoms and the hypoglycemia. These results suggest that carnitine and MCT may be effective in treating this defect of long-chain fatty acid oxidation.

Acetylcarnitine↗
PubMedDate not supplied

Cystathionine beta-synthase deficiency: effects of betaine supplementation after methionine restriction in B6-nonresponsive homocystinuria.

PURPOSE: For treatment of cystathionine beta-synthase (CbetaS) deficiency, we determined the effect of betaine (N,N,N-trimethylglycine) therapy and examined the genotype-phenotype relationships to betaine. METHODS: In five patients with B6-nonresponsive homocystinuria, we defined the CbetaS genotypes and determined metabolic responses to betaine as an additive to traditional dietary methionine restriction. RESULTS: After betaine therapy, tHcy declined (mean 47.4 micromol/L; range: -21.2 to -104.0 micromol/L; P=0.02), whereas total plasma cysteine and methionine did not change. Plasma methionine/tHcy ratios increased by 5.45 (range: +1.5 to 15.3; P=0.05) inpatients with B6-nonresponsive alleles. CONCLUSION: Betaine improves metabolic control in B6-nonresponsive patients with homocystinuria after optimum dietary control.

Adolescent↗
PubMedDate not supplied

Ionised and total serum magnesium in renal transplant patients.

BACKGROUND: Hypomagnesemia in renal transplant patients is almost always documented through total serum values (MgT), but it has recently become user-friendly to assay the biologically active, ionised fraction (Mg++). We verified the prevalence of true ionised magnesemia and the correspondence between total and ionised Mg assays in our transplanted patients, taking into account renal Mg excretion and the possible role of other reputed factors of hypomagnesemia (cyclosporine, secondary hyperparathyroidism and acid-base balance). METHODS: Thirty-eight transplanted patients (25M/13F, aged 41 +/- 11 years) and 38 age and sex matched controls were enrolled. Blood chemistries included: ionised Mg and Ca, total Mg and Ca, phosphate, creatinine, albumin, bicarbonate, alkaline phosphatase, parathyroid hormone and, in patients, cyclosporine (CyA). A 24-h urine collection (for Ca and Mg) and a fasting spot sample (for pH, Mg, Ca, phosphate, creatinine) were also obtained. RESULTS: Patients with mild renal failure (creatinine: Cr=1.75 +/- 0.83 mg/dL), mild persistent secondary hyperparathyroidism and almost normal tubular acidification capacity had MgT lower than controls (0.76 +/- 0.08 vs 0.82 +/- 0.08 mmol/L; p<0.002), with 10 cases (26%) of total hypomagnesemia. Mg++ was also significantly low (0.51 +/- 0.08 vs 0.53 +/- 0.05 mmol/L; p<0.03), but there were only four cases (10%) of true ionised hypomagnesemia. MgT and Mg++, although correlated (with a low r value: =0.49; p<0.001), showed poor correspondence in individual patients and MgT was not useful to identify cases of true ionised hypomagnesemia. Neither assay correlated with renal function. Daily urinary excretion of Mg was normal (3.5 +/- 1.3 vs 3.0 +/- 0.24 mmol/day; n.s.), with no case of definite hypomagnesuria. Fasting excretion fraction (EF) of Mg, calculated with both assays, was increased in approximately 60% of patients (EF(MgT) 4.9 +/- 2.6 vs 2.32 +/- 0.7%; p<0.0001; EF(Mg++) 7.74 +/- 4.9 vs 3.63 +/- 1.18%; p<0.0001) and positively correlated with serum Cr (r=0.62; p<0.0001 with EF(MgT); and r=0.467; p<0.005 with EF(Mg++) but not with CyA. Neither Mg assay correlated with serum CyA, calcium, phosphate, PTH or bicarbonate. CONCLUSIONS: In long term renal transplant patients not taking diuretics, the prevalence of true ionised hypomagnesemia is low. Renal insufficiency, typically associated with Mg retention, is the major cause of increased EF(Mg) and, as such, plays an antagonistic role to CyA and other factors of renal Mg wasting. Because MgT and Mg++ are not closely related, assay of the ionised fraction seems advisable in case of total hypomagnesemia. However, because diagnosis of depletion can hardly rely on serum assay alone, a fuller evaluation (urinary excretion and other clinical and biochemical signs of hypomagnesemia) is suggested before diagnosis is made.

Adult↗