RESUMO
Dried blood spot (DBS) analysis has existed for >50 years, but application of this technique to fecal analysis remains limited. To address whether dried fecal spots (DFS) could be used to measure fecal bile acids, we collected feces from five subjects for each of the following cohorts: 1) healthy individuals, 2) individuals with diarrhea, and 3) Clostridioides difficile-infected patients. Homogenized fecal extracts were loaded onto quantitative DBS (qDBS) devices, dried overnight, and shipped to the bioanalytical lab at ambient temperature. For comparison, source fecal extracts were shipped on dry ice and stored frozen. After 4 mo, frozen fecal extracts and ambient DFS samples were processed and subjected to targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics with stable isotope-labeled standards. We observed no differences in the bile acid levels measured between the traditional extraction and the qDBS-based DFS methods. This pilot data demonstrates that DFS-based analysis is feasible and warrants further development for fecal compounds and microbiome applications.NEW & NOTEWORTHY Stool analysis in remote settings can be challenging, as the samples must be stored at -80°C and transported on dry ice for downstream processing. Our work indicates that dried fecal spots (DFS) on Capitainer quantitative DBS (qDBS) devices can be stored and shipped at ambient temperature and yields the same bile acid profiles as traditional samples. This approach has broad applications for patient home testing and sample collection in rural communities or resource-limited countries.
Assuntos
Gelo-Seco , Espectrometria de Massas em Tandem , Humanos , Cromatografia Líquida/métodos , Espectrometria de Massas em Tandem/métodos , Tecnologia , Ácidos e Sais BiliaresRESUMO
BACKGROUND: Dried Blood Spot (DBS) analysis has been used for identification and quantification of diseases and disorders in large populations. Simply collecting blood or plasma samples on cotton paper, followed with an organic solvent extraction, many small molecules can be detected and quantified. In a typical procedure of DBS analysis in newborn screening, stable isotope internal standards (SIIS) are added to extraction solvent as a reference. However, this way of employing SIIS does not reflect extraction efficiency, or protein binding issues, nor does it reflect potential degradation that could occur. In addition, punched-out discs from larger DBS are known to have imprecision typically ≥ 15%. METHODS: We developed and tested an approach, internal quantitative DBS (iqDBS), which delivers an exact volume of whole blood or plasma to a paper disc that is impregnated with a dried concentration of SIIS for quantitation. Amino acids were derivatized to make butyl esters and measured using Flow Injection Analysis with Selected Reaction Monitoring (FIA-SRM). RESULTS: We demonstrated with phenylalanine and tyrosine improved sensitivity and accuracy by applying iqDBS. CONCLUSIONS: We established a new method for quantitative analysis of small molecules from dried blood spots that incorporates stable isotope internal standard at the time of blood collection.
Assuntos
Fenilalanina , Tirosina , Humanos , Recém-Nascido , Análise de Injeção de Fluxo , Teste em Amostras de Sangue Seco/métodos , Isótopos , SolventesRESUMO
Objective: To assess the longitudinal metabolic patterns during the evolution of bronchopulmonary dysplasia (BPD) development. Methods: A case-control dataset of preterm infants (<32-week gestation) was obtained from a multicenter database, including 355 BPD cases and 395 controls. A total of 72 amino acid (AA) and acylcarnitine (AC) variables, along with infants' calorie intake and growth outcomes, were measured on day of life 1, 7, 28, and 42. Logistic regression, clustering methods, and random forest statistical modeling were utilized to identify metabolic variables significantly associated with BPD development and to investigate their longitudinal patterns that are associated with BPD development. Results: A panel of 27 metabolic variables were observed to be longitudinally associated with BPD development. The involved metabolites increased from 1 predominant different AC by day 7 to 19 associated AA and AC compounds by day 28 and 16 metabolic features by day 42. Citrulline, alanine, glutamate, tyrosine, propionylcarnitine, free carnitine, acetylcarnitine, hydroxybutyrylcarnitine, and most median-chain ACs (C5:C10) were the most associated metabolites down-regulated in BPD babies over the early days of life, whereas phenylalanine, methionine, and hydroxypalmitoylcarnitine were observed to be up-regulated in BPD babies. Most calorie intake and growth outcomes revealed similar longitudinal patterns between BPD cases and controls over the first 6 weeks of life, after gestational adjustment. When combining with birth weight, the derived metabolic-based discriminative model observed some differences between those with and without BPD development, with c-statistics of 0.869 and 0.841 at day 7 and 28 of life on the test data. Conclusions: The metabolic panel we describe identified some metabolic differences in the blood associated with BPD pathogenesis. Further work is needed to determine whether these compounds could facilitate the monitoring and/or investigation of early-life metabolic status in the lung and other tissues for the prevention and management of BPD.
Assuntos
Displasia Broncopulmonar , Peso ao Nascer , Estudos de Casos e Controles , Idade Gestacional , Humanos , Lactente , Recém-Nascido , Recém-Nascido PrematuroRESUMO
Necrotizing Enterocolitis (NEC) is associated with prematurity, enteral feedings, and enteral dysbiosis. Accordingly, we hypothesized that along with nutritional variability, metabolic dysfunction would be associated with NEC onset. Methods: We queried a multicenter longitudinal database that included 995 preterm infants (<32 weeks gestation) and included 73 cases of NEC. Dried blood spot samples were obtained on day of life 1, 7, 28, and 42. Metabolite data from each time point included 72 amino acid (AA) and acylcarnitine (AC) measures. Nutrition data were averaged at each of the same time points. Odds ratios and 95% confidence intervals were calculated using samples obtained prior to NEC diagnosis and adjusted for potential confounding variables. Nutritional and metabolic data were plotted longitudinally to determine relationship to NEC onset. Results: Day 1 analyte levels of alanine, phenylalanine, free carnitine, C16, arginine, C14:1/C16, and citrulline/phenylalanine were associated with the subsequent development of NEC. Over time, differences in individual analyte levels associated with NEC onset shifted from predominantly AAs at birth to predominantly ACs by day 42. Subjects who developed NEC received significantly lower weight-adjusted total calories (p < 0.001) overall, a trend that emerged by day of life 7 (p = 0.020), and persisted until day of life 28 (p < 0.001) and 42 (p < 0.001). Conclusion: Premature infants demonstrate metabolic differences at birth. Metabolite abnormalities progress in parallel to significant differences in nutritional delivery signifying metabolic dysfunction in premature newborns prior to NEC onset. These observations provide new insights to potential contributing pathophysiology of NEC and opportunity for clinical care-based prevention.
Assuntos
Aminoácidos/metabolismo , Enterocolite Necrosante/etiologia , Fenômenos Fisiológicos da Nutrição do Lactente/fisiologia , Recém-Nascido Prematuro/metabolismo , Doenças Metabólicas/etiologia , Distúrbios Nutricionais/etiologia , Estado Nutricional , Análise de Dados , Bases de Dados como Assunto , Enterocolite Necrosante/prevenção & controle , Feminino , Humanos , Recém-Nascido , Estudos Longitudinais , Masculino , Doenças Metabólicas/metabolismo , Estudos Multicêntricos como Assunto , Distúrbios Nutricionais/metabolismoRESUMO
OBJECTIVE: This study aimed to determine whether vaccination during pregnancy, prematurity, and staphylococci concentration influenced the presence of B. cereus or staphylococcal enterotoxins (SEs) in raw human milk from healthy mothers. STUDY DESIGN: Human milk samples were collected from 152 healthy women. B. cereus, S. aureus and coagulase-negative staphylococci (CNS) were enumerated using selective agar culture media. The detection of B. cereus spores and SEs were determined using ELISA. RESULTS: CNS and B. cereus concentrations in milk from non-vaccinated mothers were higher than that from mothers vaccinated during pregnancy, but S. aureus did not differ. Prematurity did not affect B. cereus or staphylococci in human milk. S. aureus and CNS concentrations in human milk with the presence of B. cereus were higher than that with the absence of B. cereus. Viable B. cereus was present in 9.2% of raw human milk samples whereas SEs were not detected in any samples. CONCLUSIONS: Vaccination during pregnancy and low concentration of staphylococci could reduce the risk of B. cereus in raw human milk. The screening of B. cereus in raw human milk must be performed before pasteurization to reduce the risk of B. cereus infection in preterm infants.
Assuntos
Bacillus cereus , Staphylococcus , Animais , Feminino , Microbiologia de Alimentos , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Leite , Leite Humano , Gravidez , Staphylococcus aureus , VacinaçãoRESUMO
Abstract Phenylalanine analysis for phenylketonuria (PKU) detection in newborn screening (NBS) was chosen as the model system to describe how advancements in laboratory technology improved laboratory performance. These advancements have made NBS programs better and have improved the health outcomes of the affected newborn through improvements in accurate early detection over the past 50 years. The most current state-of-the-art technology, tandem mass spectrometry (MS/MS), has proven that it is now the choice in almost all modern NBS facilities because it is a versatile instrument that continues to grow in its application not just for amino acid and acylcarnitine detection but for other metabolites and disorders such as lysosomal storage diseases and second-tier detection of some screen-positive results. The use of MS/MS will continue to expand, even with the anticipated introduction and expansion of molecular screening methods into NBS programs. Regarding technological advancements, the future of NBS will include even newer technologies and approaches that will enhance the detection and treatment of newborns affected by PKU and other inborn errors of metabolism.
RESUMO
BACKGROUND: 3-Hydroxypalmitoleoyl-carnitine (C16:1-OH) has recently been reported to be elevated in acylcarnitine profiles of patients with propionic acidemia (PA) or methylmalonic acidemia (MMA) during expanded newborn screening (NBS). High levels of C16:1-OH, combined with other hydroxylated long chain acylcarnitines are related to long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) and trifunctional protein (TFP) deficiency. METHODS: The acylcarnitine profile of two LCHADD patients was evaluated using liquid chromatography-tandem mass spectrometric method. A specific retention time was determined for each hydroxylated long chain acylcarnitine. The same method was applied to some neonatal dried blood spots (DBSs) from PA and MMA patients presenting abnormal C16:1-OH concentrations. RESULTS: The retention time of the peak corresponding to C16:1-OH in LCHADD patients differed from those in MMA and PA patients. Heptadecanoylcarnitine (C17) has been identified as the novel biomarker specific for PA and MMA patients through high resolution mass spectrometry (Orbitrap) experiments. We found that 21 out of 23 neonates (22 MMA, and 1PA) diagnosed through the Tuscany region NBS program exhibited significantly higher levels of C17 compared to controls. Twenty-three maternal deficiency (21 vitamin B12 deficiency, 1 homocystinuria and 1 gastrin deficiency) samples and 82 false positive for elevated propionylcarnitine (C3) were also analyzed. CONCLUSIONS: We have characterized a novel biomarker able to detect propionate disorders during expanded newborn screening (NBS). The use of this new biomarker may improve the analytical performances of NBS programs especially in laboratories where second tier tests are not performed.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos/sangue , Erros Inatos do Metabolismo dos Aminoácidos/diagnóstico , Carnitina/análogos & derivados , Carnitina/sangue , Triagem Neonatal , Acidemia Propiônica/sangue , Acidemia Propiônica/diagnóstico , Biomarcadores/sangue , Humanos , Recém-Nascido , Estudos RetrospectivosRESUMO
OBJECTIVE: To describe the influence that gestational age and chronological age have on amino acid and acylcarnitine profiles in an at-risk population of premature infants. METHODS: Metabolic profiles (15 amino acids and 35 acylcarnitines) were obtained by using standard newborn techniques on infants born between 23 and 31 completed weeks of gestation. The profiles were drawn within the first 24 hours after birth and on approximately days 7, 28, and 42 of life or at discharge. A single, central, contract laboratory analyzed and managed the samples. RESULTS: We studied 995 patients; none was subsequently diagnosed with an inborn error of metabolism. Of the 3579 samples, there were 257 (7.2%) amino acid or acylcarnitine alerts reported in 214 infants (21.5% of infants studied). Both gestational age and postbirth chronological age significantly influenced the metabolic profile. Twenty-nine percent of infants at 23 to 26 weeks' gestational age had an abnormal metabolic profile compared with 17% of infants at 29 to 31 weeks' gestational age (P < .01). On the day of birth, 12% of the profiles were abnormal compared with 2% on day 28 (P < .01). The highest rate of abnormal values occurred on day 7 in the infants 23 to 26 weeks' gestational age (21%). CONCLUSIONS: These results demonstrate the complexity of understanding the impact of immaturity and disease on metabolic profiles used to screen for inborn errors of metabolism. Our data provide reference values for studies aimed at better understanding metabolism in preterm infants.
Assuntos
Aminoácidos/metabolismo , Carnitina/análogos & derivados , Idade Gestacional , Recém-Nascido Prematuro/metabolismo , Metaboloma , Fatores Etários , Carnitina/metabolismo , Feminino , Humanos , Recém-Nascido , MasculinoRESUMO
Consumption of trans-unsaturated fatty acids promotes atherosclerosis, but whether degradation of fats in macrophages is altered by trans-unsaturated fatty acids is unknown. We compared the metabolism of oleate (C18:1Δ9-10 cis; (Z)-octadec-9-enoate), elaidate (C18:Δ9-10 trans; (E)-octadec-9-enoate), and stearate (C18:0, octadecanoate) in adherent peripheral human macrophages. Metabolism was followed by measurement of acylcarnitines in cell supernatants by MS/MS, determination of cellular fatty acid content by GC/MS, and assessment of ß-oxidation rates using radiolabeled fatty acids. Cells incubated for 44 h in 100 µM elaidate accumulated more unsaturated fatty acids, including both longer- and shorter-chain, and had reduced C18:0 relative to those incubated with oleate or stearate. Both C12:1 and C18:1 acylcarnitines accumulated in supernatants of macrophages exposed to trans fats. These results suggested ß-oxidation inhibition one reaction proximal to the trans bond. Comparison of [1-(14)C]oleate to [1-(14)C]elaidate catabolism showed that elaidate completed the first round of fatty acid ß-oxidation at rates comparable to oleate. Yet, in competitive ß-oxidation assays with [9,10-(3)H]oleate, tritium release rate decreased when unlabeled oleate was replaced by the same quantity of elaidate. These data show specific inhibition of monoenoic fat catabolism by elaidate that is not shared by other atherogenic fats.
Assuntos
Macrófagos/metabolismo , Ácido Oleico/farmacologia , Carnitina/análogos & derivados , Carnitina/análise , Carnitina/metabolismo , Células Cultivadas , Ácidos Graxos/análise , Ácidos Graxos/química , Ácidos Graxos/farmacologia , Humanos , Macrófagos/efeitos dos fármacos , Ácido Oleico/química , Ácido Oleico/metabolismo , Ácidos Oleicos , Oxirredução/efeitos dos fármacos , Óleos de Plantas/farmacologia , Estearatos/metabolismo , Estearatos/farmacologia , Espectrometria de Massas em TandemRESUMO
The use of DBS is an appealing approach to employing microsampling techniques for the bioanalysis of samples, as has been demonstrated for the past 50 years in the metabolic screening of metabolites and diseases. In addition to its minimally invasive sample collection procedures and its economical merits, DBS microsampling benefits from the very high sensitivity, selectivity and multianalyte capabilities of LC-MS, which has been especially well demonstrated in newborn screening applications. Only a few microliters of a biological fluid are required for analysis, which also translates to significantly reduced demands on clinical samples from patients or from animals. Recently, the pharmaceutical industry and other arenas have begun to explore the utility and practicality of DBS microsampling. This review discusses the basis for why DBS techniques are likely to be part of the future, as well as offering insights into where these benefits may be realized.
Assuntos
Cromatografia Líquida/normas , Teste em Amostras de Sangue Seco/normas , Espectrometria de Massas em Tandem/normas , Animais , Coleta de Amostras Sanguíneas/normas , Celulose/química , Cromatografia Líquida/instrumentação , Dopagem Esportivo/métodos , Teste em Amostras de Sangue Seco/instrumentação , Filtração , Ciências Forenses/métodos , Hematócrito , Humanos , Recém-Nascido , Camundongos , Porosidade , Padrões de Referência , Espectrometria de Massas em Tandem/instrumentaçãoRESUMO
CONTEXT: In longitudinal studies of adults, elevated amino acid (AA) concentrations predicted future type 2 diabetes mellitus (T2DM). OBJECTIVE: The aim of the present investigation was to examine whether increased plasma AA concentrations are associated with impaired ß-cell function relative to insulin sensitivity [i.e. disposition index (DI)], a predictor of T2DM development. DESIGN, SETTING, AND PARTICIPANTS: Metabolomic analysis for fasting plasma AAs was performed by tandem mass spectrometry in 139 normal-weight and obese adolescents with and without dysglycemia. First-phase insulin secretion was evaluated by a hyperglycemic (â¼225 mg/dl) clamp and insulin sensitivity by a hyperinsulinemic-euglycemic clamp. DI was calculated as the product of first-phase insulin and insulin sensitivity. RESULTS: DI was positively associated with branched-chain AAs (leucine/isoleucine and valine; r = 0.27 and 0.29, P = 0.001), neutrally transported AAs (phenylalanine and methionine; r = 0.30 and 0.35, P < 0.001), basic AAs (histidine and arginine; r = 0.28 and 0.23, P ≤ 0.007), serine (r = 0.35, P < 0.001), glycine (r = 0.26, P = 0.002), and branched-chain AAs-derived intermediates C3, C4, and C5 acylcarnitine (range r = 0.18-0.19, P ≤ 0.04). CONCLUSION: In youth, increased plasma AA concentrations are not associated with a heightened metabolic risk profile for T2DM; rather, they are positively associated with ß-cell function relative to insulin sensitivity. These contrasting observations between adults and youth may be a reflection of developmental differences along the lifespan dependent on the combined impact of the aging process together with the impact of progressive obesity.
Assuntos
Aminoácidos/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Resistência à Insulina/fisiologia , Células Secretoras de Insulina/fisiologia , Obesidade/metabolismo , Adolescente , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Feminino , Humanos , Insulina/metabolismo , Masculino , Obesidade/sangue , Obesidade/fisiopatologia , Valor Preditivo dos TestesRESUMO
OBJECTIVE: Increased plasma concentrations of the endogenous nitric oxide synthase inhibitor, asymmetric dimethylarginine, decreased arginine bioavailability, and mitochondrial dysfunction have been reported in adult sepsis. We studied whether asymmetric dimethylarginine, arginine, and carnitine metabolism (a measure of mitochondrial dysfunction) are altered in pediatric sepsis and whether these are clinically useful biomarkers. DESIGN: : Prospective, observational study. SETTING: Pediatric intensive care unit at an academic medical center. PATIENTS: : Ninety patients ≤ 18 yrs old, 30 with severe sepsis or septic shock, compared with 30 age-matched febrile and 30 age-matched healthy control subjects. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Plasma asymmetric dimethylarginine and whole blood arginine, citrulline, ornithine, and acylcarnitine:free carnitine ratio were measured daily for septic patients and once for control subjects using tandem mass spectrometry. Plasma asymmetric dimethylarginine concentration (median; interquartile range µmol/L) on day 1 was lower in severe sepsis and septic shock (0.38; 0.30-0.56) compared with febrile (0.45; 0.40-0.59) and healthy (0.60; 0.54-0.67) control subjects (p < .001), although decreased asymmetric dimethylarginine was predominantly found in neutropenic patients. Day 1 arginine was lower in septic (10; interquartile range, 7-20 µmol/L) compared with healthy patients (32; interquartile range, 23-40; p < .001), and the arginine:ornithine ratio was decreased in sepsis, indicating increased arginase activity (an alternative pathway for arginine metabolism). The arginine:asymmetric dimethylarginine and acylcarnitine:free carnitine ratios did not differ between septic and control patients. Asymmetric dimethylarginine was inversely correlated with organ dysfunction by Pediatric Logistic Organ Dysfunction score (r = -0.50, p = .009), interleukin-6 (r = -0.55, p = .01), and interleukin-8 (r = -0.52, p = .03) on admission. Arginine, arginine:asymmetric dimethylarginine, and acylcarnitine:free carnitine were not associated with organ dysfunction or outcomes. CONCLUSIONS: Asymmetric dimethylarginine was decreased in pediatric sepsis and was inversely associated with inflammation and organ dysfunction. This suggests that inhibition of nitric oxide synthase by asymmetric dimethylarginine accumulation is unlikely to impact sepsis pathophysiology in septic children despite decreased arginine bioavailability. We did not find an association of asymmetric dimethylarginine with altered carnitine metabolism nor were asymmetric dimethylarginine, arginine, and acylcarnitine:free carnitine useful as clinical biomarkers.
Assuntos
Arginina/análogos & derivados , Arginina/sangue , Carnitina/sangue , Sepse/sangue , Adolescente , Estudos de Casos e Controles , Criança , Pré-Escolar , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Estudos ProspectivosAssuntos
Aminoácidos/química , Coleta de Amostras Sanguíneas/métodos , Compostos de Boro/sangue , Compostos de Boro/farmacocinética , Sistema Nervoso Central/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão/métodos , Oxazolidinonas/sangue , Oxazolidinonas/farmacocinética , Espectrometria de Massas em Tandem/métodos , Animais , MasculinoRESUMO
OBJECTIVE: We compared acylcarnitine (AcylCN) species, common amino acid and fat oxidation (FOX) byproducts, and plasma amino acids in normal weight (NW; n = 39), obese (OB; n = 64), and type 2 diabetic (n = 17) adolescents. RESEARCH DESIGN AND METHODS: Fasting plasma was analyzed by tandem mass spectrometry, body composition by dual energy X-ray absorptiometry and computed tomography, and total-body lipolysis and substrate oxidation by [(2)H(5)]glycerol and indirect calorimetry, respectively. In vivo insulin sensitivity (IS) was assessed with a 3-h hyperinsulinemic-euglycemic clamp. RESULTS: Long-chain AcylCNs (C18:2-CN to C14:0-CN) were similar among the three groups. Medium- to short-chain AcylCNs (except C8 and C10) were significantly lower in type 2 diabetes compared with NW, and when compared with OB, C2-, C6-, and C10-CN were lower. Amino acid concentrations were lower in type 2 diabetes compared with NW. Fasting lipolysis and FOX were higher in OB and type 2 diabetes compared with NW, and the negative association of FOX to C10:1 disappeared after controlling for adiposity, Tanner stage, and sex. IS was lower in OB and type 2 diabetes with positive associations between IS and arginine, histidine, and serine after adjusting for adiposity, Tanner stage, and sex. CONCLUSIONS: These metabolomics results, together with the increased rates of in vivo FOX, are not supportive of defective fatty acid or amino acid metabolism in obesity and type 2 diabetes in youth. Such observations are consistent with early adaptive metabolic plasticity in youth, which over time-with continued obesity and aging-may become dysfunctional, as observed in adults.
Assuntos
Aminoácidos/metabolismo , Diabetes Mellitus Tipo 2/embriologia , Ácidos Graxos/metabolismo , Obesidade/embriologia , Absorciometria de Fóton , Adolescente , Carnitina/análogos & derivados , Carnitina/metabolismo , Jejum , Feminino , Humanos , MasculinoRESUMO
BACKGROUND: Markers derived from dextrose (d-glucose) are observed in the MS/MS-based acylcarnitine profiles from dried-blood spots of some premature infants receiving intravenous nutrition. The presence of these markers at m/z 325, 399 and 473 are thought to arise from contamination of blood by total parenteral nutrition (TPN) solutions during specimen collection from premature infants. These solutions contain high concentrations of amino acids and as a result, false-positive screening results for amino acid disorders may occur. This study investigates quantitative parameters of dextrose and amino acids in blood samples enriched with different TPN solutions. METHODS: Whole blood collected in heparin was enriched with three different TPN solutions containing 5, 10 or 12.5% dextrose and amino acids that were originally prepared for delivery of 2.5, 3 or 4 g/kg/day of Premasol® then spotted onto filter paper cards. Acylcarnitine and amino acid profiles using MS/MS were obtained. Ion ratios of dextrose relative to specific acylcarnitine stable isotope internal standards and amino acid concentrations were obtained. RESULTS: The ion ratios for each of the dextrose markers at m/z 325, 399 and 473 exhibit linearity with the concentration of the dextrose component of TPN added to blood. The lowest detectable dextrose concentration added to blood was 7.6 mmol/l at 1:80 v/v TPN in blood. Furthermore, the concentrations of amino acids were linear with the concentration of the amino acid component of TPN added to blood. At the lowest detectable concentrations of dextrose marker, the amino acid concentrations were at or above the values considered abnormal in newborn screening laboratories. The molar ratios of amino acids approached the relative quantity of amino acid in the TPN solution with increasing enrichments in blood. CONCLUSIONS: Detection of the combinations of dextrose markers, very high elevations of amino acids and unusual molar ratios can be used to reject a specimen as improperly collected rather than declaring it a false positive and hence reduce false positive rates. This process enhances efficiency, reduces parental anxiety, and improves positive predictive values.
Assuntos
Aminoácidos/sangue , Coleta de Amostras Sanguíneas , Triagem Neonatal , Nutrição Parenteral Total/métodos , Humanos , Recém-Nascido , Sensibilidade e EspecificidadeRESUMO
The use of tandem mass spectrometry (MS/MS) for screening of inherited metabolic disease in newborns has afforded many unique opportunities in the understanding of the benefits early their early detection, diagnosis and treatment. From the standpoint of the laboratory and modern analytical methods, the use of MS based analysis demonstrated that a multiple metabolite-multiple disease screen-one method approach expanded screening significantly. MS/MS and newborn screening has served as a model of one type of approach in preventative health care that has shown proven benefits. It has been nearly 20 years since the introduction of MS/MS analysis of dried blood spots from newborns. There have been many lessons learned in both the analytical approach as well as follow-up at the bedside. These lessons can be applied to future applications of MS/MS in newborn screening as well as other areas of metabolism and metabolic profiles such as that from acquired disease, environmental disease and other factors such as nutrition and age. The use of a highly specific, sensitive and multiplex platform such as MS/MS will continue to grow and experience in the newborn screening application will insure this outcome.
Assuntos
Perfilação da Expressão Gênica/métodos , Doenças Metabólicas/sangue , Doenças Metabólicas/diagnóstico , Triagem Neonatal/métodos , Sistemas Automatizados de Assistência Junto ao Leito , Espectrometria de Massas em Tandem/métodos , Biomarcadores/sangue , Feminino , Humanos , Recém-Nascido , Masculino , Tecnologia FarmacêuticaRESUMO
BACKGROUND: The use of tandem mass spectrometry (MS/MS) for the analysis of amino acids and acylcarnitines from dried-blood spots (DBS) has become routine practice in newborn screening laboratories. The Newborn Screening Quality Assurance Program (NSQAP) added 3-hydroxyisovalerylcarnitine (C5OH) into its routine quality control and proficiency testing (PT) DBS materials for MS/MS to assure the quality of C5OH screening. We report the results from NSQAP evaluations for C5OH-enriched DBS, and summarize participant screening practices based on their analytical methods. METHODS: NSQAP prepared C5OH-enriched DBS materials for its participants. Laboratories reported quantitative and qualitative results. Bias plots of quantitative results were constructed using reported data and the results were sorted by an analytical method. RESULTS: NSQAP participants reported PT specimen 3964 as outside of normal limits for C5OH. The mean C5OH value for derivatized and non-derivatized methods was 2.80 and 2.67 µmol/l, respectively. Reported data from other specimens showed a similar trend in derivatized vs. non-derivatized assay results. Differences in C5OH quantitative values were observed among laboratories using different internal standards. CONCLUSIONS: C5OH MS/MS measurements in DBS assays varied by method and the choice of internal standards. The use of NSQAP's DBS materials allows harmonization of C5OH measurements by newborn screening laboratories worldwide.