Bio

Clinical Focus


  • Pathology
  • Pathology and Laboratory Medicine

Academic Appointments


  • Associate Professor - Med Center Line, Pathology
  • Associate Professor - Med Center Line (By courtesy), Pediatrics

Administrative Appointments


  • Board of Directors, American Board of Medical Genetics (2006 - 2011)
  • Laboratory Quality Assurance Committee, American College of American Genetics (2003 - 2007)
  • Faculty Senate, Stanford University School of Medicine (2005 - 2008)
  • Committee on Courses and Curriculum, Stanford University School of Medicine (2006 - Present)

Professional Education


  • Fellowship:University of Maryland Baltimore (12/31/1989)
  • University of California Los Angeles School of Medicine (3/28/1986) CA
  • Board Certification: Medical Biochemical Genetics, American Board of Medical Genetics (1990)
  • Board Certification: Medical Genetics, American Board of Medical Genetics (1990)
  • B.A., UCLA, Biology (1979)
  • Ph.D., UCLA, Genetics (1986)

Research & Scholarship

Current Research and Scholarly Interests


Translational research activities are aimed at the development of new laboratory testing approaches for the diagnosis and monitoring of patients with inborn errors of metabolism. In particular, a tandem-mass spectrometry (MS/MS)-based test for glutathione, an important antioxidant, is being applied to the evaluation of patients with various metabolic disorders including mitochondrial myopathies. Results of these studies will further our understanding of the pathophysiology of metabolic diseases, with the ultimate aim of improving patient testing and developing new theraputic strategies.

Teaching

2013-14 Courses


Graduate and Fellowship Programs


Publications

Journal Articles


  • A rapid, sensitive method for quantitative analysis of underivatized amino acids by liquid chromatography-tandem mass spectrometry (LC-MS/MS) JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES Le, A., Ng, A., Kwan, T., Cusmano-Ozog, K., Cowan, T. M. 2014; 944: 166-174

    Abstract

    The quantitation of free amino acids from physiologic samples is essential for diagnosing and monitoring patients with inherited metabolic disorders. Current methods are hindered by long preparative and/or analysis times, expensive reagents, and often suboptimal performance characteristics. To overcome these challenges, a improved method for amino acid analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed and validated. Samples were deproteinized with sulfosalicylic acid and supernatants diluted with tridecafluoroheptanoic acid. Chromatographic separation of amino acids occurred using two columns, with conditions favoring resolution of isobaric compounds and minimizing ion suppression. Eluted compounds were detected by selective reaction monitoring, and quantitated by relating peak areas of amino acids to externally run standards. Validation studies evaluated linearity, within- and between-run imprecision, lower limits of detection and quantification for 33 amino acids, and correlation with the Biochrom 30 Amino Acid Analyzer. Total run time including re-equilibration was 15min per sample. Within-run precision averaged 2.8% for all compounds, with an average linear correlation coefficient of 0.995. The majority of compounds were reliably quantitated at ≤0.1μM. Between-run precision averaged 4.0%. Results showed excellent correlation with the Biochrom 30 amino acid analyzer with an average overall correlation of 0.908. We conclude that our method is extremely sensitive, specific and reproducible and represents an improvement over other currently available technologies.

    View details for DOI 10.1016/j.jchromb.2013.11.017

    View details for Web of Science ID 000329770300027

    View details for PubMedID 24316529

  • A new LC-MS/MS method for the clinical determination of reduced and oxidized glutathione from whole blood. Journal of chromatography. B, Analytical technologies in the biomedical and life sciences Moore, T., Le, A., Niemi, A., Kwan, T., Cusmano-Ozog, K., Enns, G. M., Cowan, T. M. 2013; 929: 51-55

    Abstract

    Reduced levels of glutathione (?-glutamylcysteinylglycine, GSH) and the ratio of GSH to glutathione disulfide (GSSG) can serve as important indicators of oxidative stress and disease risk. Measured concentrations of GSH and GSSG vary widely between laboratories, largely due to the instability of GSH during sample handling and variables arising from different analytical methods. We have developed a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring whole blood GSH and GSSG that minimizes preanalytic and analytic variability, reliably eliminates interference from ion suppression, and can easily be implemented in clinical laboratories. Samples were deproteinized with sulfosalicylic acid (SSA) and derivatized with N-ethylmaleimide (NEM) in a single preparative step, and the resulting supernatants combined with stable-isotope internal standards (GSH-(13)C, (15)N-NEM and GSSG-(13)C,(15)N), subjected to chromatographic separation using a Hypercarb column, and analyzed by MS/MS in the positive-ion mode. Results showed excellent linearity for both GSH and GSSG over the ranges of physiologic normal, with inter- and intra-assay CV's of 3.1-4.3% and accuracy between 95% and 101%. The lower limits of detection (LLOD) were 0.4?M for GSH and 0.1?M for GSSG and the lower limits of quantitation (LLOQ) were 1.5?M for GSH and 0.1?M for GSSG. Derivatized samples are stable for at least 3 years when stored at -80°C, and underivatized samples for at least 24h at either 4°C or room temperature. Reference intervals were determined for 59 control samples, and were (mean±SD): GSH 900±140?M; GSSG 1.17±0.43?M; GSH/GSSG 880±370.

    View details for DOI 10.1016/j.jchromb.2013.04.004

    View details for PubMedID 23660247

  • Liver transplantation for urea cycle disorders in pediatric patients: A single-center experience PEDIATRIC TRANSPLANTATION Kim, I. K., Niemi, A., Krueger, C., Bonham, C. A., Concepcion, W., Cowan, T. M., Enns, G. M., Esquivel, C. O. 2013; 17 (2): 158-167

    Abstract

    LT has emerged as a surgical treatment for UCDs. We hypothesize that LT can be safely and broadly utilized in the pediatric population to effectively prevent hyperammonemic crises and potentially improve neurocognitive outcomes. To determine the long-term outcomes of LT for UCDs, charts of children with UCD who underwent LT were retrospectively reviewed at an academic institution between July 2001 and May 2012. A total of 23 patients with UCD underwent LT at a mean age of 3.4 yr. Fifteen (65%) patients received a whole-liver graft, seven patients (30%) received a reduced-size graft, and one patient received a living donor graft. Mean five-yr patient survival was 100%, and allograft survival was 96%. Mean peak blood ammonia (NH(3) ) at presentation was 772 ?mol/L (median 500, range 178-2969, normal <30-50). After transplantation, there were no episodes of hyperammonemia. Eleven patients were diagnosed with some degree of developmental delay before transplantation, which remained stable or improved after transplantation. Patients without developmental delay before transplantation maintained their cognitive abilities at long-term follow-up. LT was associated with the eradication of hyperammonemia, removal of dietary restrictions, and potentially improved neurocognitive development. Long-term follow-up is underway to evaluate whether LT at an early age (<1 yr) will attain improved neurodevelopmental outcomes.

    View details for DOI 10.1111/petr.12041

    View details for Web of Science ID 000315467000017

    View details for PubMedID 23347504

  • ß-Galactosidosis in Patient with Intermediate GM1 and MBD Phenotype. JIMD reports Moore, T., Bernstein, J. A., Casson-Parkin, S., Cowan, T. M. 2013; 7: 77-79

    Abstract

    A 5-year-old girl with clinical and biochemical phenotypes encompassing both GM1-gangliosidosis (GM1) and Morquio B disease (MBD) is described. Mild generalized skeletal dysplasia and keratan sulfaturia were consistent with a diagnosis of MBD, while developmental delay and GM1-specific oligosacchariduria were consistent with GM1 gangliosidosis. No observable ?-galactosidase activity was detected in leukocytes, and two mutations, p.R201H (c.602G>A) and p.G311R (c.931G>A), were identified by gene sequencing. The R201H substitution has been previously reported in patients with both GM1 and MBD, and G311R is a novel mutation. Our patient represents a further example of the clinical heterogeneity that can result from mutations at the ?-galactosidase locus.

    View details for DOI 10.1007/8904_2012_145

    View details for PubMedID 23430499

  • Increased incidence of profound biotinidase deficiency among Hispanic newborns in California MOLECULAR GENETICS AND METABOLISM Cowan, T. M., Kazerouni, N. N., Dharajiya, N., Lorey, F., Roberson, M., Hodgkinson, C., Schrijver, I. 2012; 106 (4): 485-487

    Abstract

    We report population findings from newborn screening for biotinidase deficiency in California, representing over 2,000,000 newborns. The incidence of profound deficiency was 1/73,629, higher than in other reported populations. Out of 28 patients with profound biotinidase deficiency, 19 were of Hispanic descent, suggesting an increased frequency among this group. Of the 28 patients, 23 underwent mutation analysis of the BTD gene, with one common mutation, 528G>T, found in 43.3% of Hispanic alleles tested.

    View details for DOI 10.1016/j.ymgme.2012.05.017

    View details for Web of Science ID 000307322100015

    View details for PubMedID 22698809

  • An improved LC-MS/MS method for the detection of classic and low excretor glutaric acidemia type 1 JOURNAL OF INHERITED METABOLIC DISEASE Moore, T., Le, A., Cowan, T. M. 2012; 35 (3): 431-435

    Abstract

    Glutaric acidemia type I (GA1) is associated with elevated glutarylcarnitine (C5DC), typically measured as its butylester by acylcarnitine profile analysis using tandem mass spectrometry (MS/MS) and the precursor-product ion pair of m/z 388-85. This method neither distinguishes between C5DC and its isomer 3-hydroxydecanoylcarnitine (C10-OH) nor reliably detects the low-excretor variant of GA1, leading to both false-positive and false-negative results when testing for GA1. To overcome these limitations, we developed an LC-MS/MS method that discriminates C5DC from C10-OH by the use of precursor-product ion pairs specific for butylated C5DC (m/z 388-115) and underivatized C10-OH (m/z 332-85). The C5DC method was validated over the linearity range of 0.025-20 ?M with a lower limit of quantification (LOQ) of 0.025 ?M. Excellent precision and accuracy were also observed. We tested plasma samples from 10 patients with confirmed GA1 (including 3 with the low-excretor variant), 21 patients with mild elevations of C5DC or C10-OH by routine acylcarnitine analysis for which GA1 ultimately was excluded, and 29 normal controls. By using the m/z 388-115 ion pair, all cases of GA1, including the low-excretor variant, were reliably distinguished from normal controls. By using the m/z 388-85 pair, patients with ambiguous elevations of C5DC or C10-OH demonstrated clearly elevated levels of C10-OH (m/z 332-85) but normal C5DC (m/z 388-115), confirming that the apparent elevation of C5DC is due to interference by C10-OH. Our method results in excellent detection of GA1, including the low-excretor variant, and also provides a means to discriminate C5DC and C10-OH in follow-up testing and routine acylcarnitine studies.

    View details for DOI 10.1007/s10545-011-9405-6

    View details for Web of Science ID 000302492300007

    View details for PubMedID 22005781

  • A Novel Mutation in the HSD17B10 Gene of a 10-Year-Old Boy with Refractory Epilepsy, Choreoathetosis and Learning Disability PLOS ONE Seaver, L. H., He, X., Abe, K., Cowan, T., Enns, G. M., Sweetman, L., Philipp, M., Lee, S., Malik, M., Yang, S. 2011; 6 (11)

    Abstract

    Hydroxysteroid (17beta) dehydrogenase 10 (HSD10) is a mitochondrial multifunctional enzyme encoded by the HSD17B10 gene. Missense mutations in this gene result in HSD10 deficiency, whereas a silent mutation results in mental retardation, X-linked, syndromic 10 (MRXS10). Here we report a novel missense mutation found in the HSD17B10 gene, namely c.194T>C transition (rs104886492), brought about by the loss of two forked methyl groups of valine 65 in the HSD10 active site. The affected boy, who possesses mutant HSD10 (p.V65A), has a neurological syndrome with metabolic derangements, choreoathetosis, refractory epilepsy and learning disability. He has no history of acute decompensation or metabolic acidosis whereas his urine organic acid profile, showing elevated levels of 2-methyl-3-hydroxybutyrate and tiglylglycine, is characteristic of HSD10 deficiency. His HSD10 activity was much lower than the normal control level, with normal β-ketothiolase activity. The c.194T>C mutation in HSD17B10 can be identified by the restriction fragment polymorphism analysis, thereby facilitating the screening of this novel mutation in individuals with intellectual disability of unknown etiology and their family members much easier. The patient's mother is an asymptomatic carrier, and has a mixed ancestry (Hawaiian, Japanese and Chinese). This demonstrates that HSD10 deficiency patients are not confined to a particular ethnicity although previously reported cases were either Spanish or German descendants.

    View details for DOI 10.1371/journal.pone.0027348

    View details for Web of Science ID 000297792400006

    View details for PubMedID 22132097

  • The role of vanin-1 and oxidative stress-related pathways in distinguishing acute and chronic pediatric ITP BLOOD Zhang, B., Lo, C., Shen, L., Sood, R., Jones, C., Cusmano-Ozog, K., Park-Snyder, S., Wong, W., Jeng, M., Cowan, T., Engleman, E. G., Zehnder, J. L. 2011; 117 (17): 4569-4579

    Abstract

    Pediatric immune thrombocytopenia (ITP) is usually self-limited. However, approximately 20% of children develop chronic ITP, which can be associated with significant morbidity because of long-term immunosuppression and splenectomy in refractory cases. To explore the molecular mechanism of chronic ITP compared with acute ITP, we studied 63 pediatric patients with ITP. Gene expression analysis of whole blood revealed distinct signatures for acute and chronic ITP. Oxidative stress-related pathways were among the most significant chronic ITP-associated pathways. Overexpression of VNN1, an oxidative stress sensor in epithelial cells, was most strongly associated with progression to chronic ITP. Studies of normal persons demonstrated VNN1 expression in a variety of blood cells. Exposure of blood mononuclear cells to oxidative stress inducers elicited dramatic up-regulation of VNN1 and down-regulation of PPAR?, indicating a role for VNN1 as a peripheral blood oxidative stress sensor. Assessment of redox state by tandem mass spectrometry demonstrated statistically significant lower glutathione ratios in patients with ITP versus healthy controls; lower glutathione ratios were also seen in untreated patients with ITP compared with recently treated patients. Our work demonstrates distinct patterns of gene expression in acute and chronic ITP and implicates oxidative stress pathways in the pathogenesis of chronic pediatric ITP.

    View details for DOI 10.1182/blood-2010-09-304931

    View details for Web of Science ID 000289984800022

    View details for PubMedID 21325602

  • Commentary. Clinical chemistry Cowan, T. M. 2011; 57 (4): 548-549

    View details for DOI 10.1373/clinchem.2010.160333

    View details for PubMedID 21444739

  • Technical standards and guidelines for the diagnosis of biotinidase deficiency GENETICS IN MEDICINE Cowan, T. M., Blitzer, M. G., Wolf, B. 2010; 12 (7): 464-470

    Abstract

    Biotinidase deficiency is an autosomal recessively inherited disorder of biotin recycling that is associated with neurologic and cutaneous consequences if untreated. Fortunately, the clinical features of the disorder can be ameliorated or prevented by administering pharmacological doses of the vitamin biotin. Newborn screening and confirmatory diagnosis of biotinidase deficiency encompasses both enzymatic and molecular testing approaches. These guidelines were developed to define and standardize laboratory procedures for enzymatic biotinidase testing, to delineate situations for which follow-up molecular testing is warranted, and to characterize variables that can influence test performance and interpretation of results.

    View details for DOI 10.1097/GIM.0b013e3181e4cc0f

    View details for Web of Science ID 000279891300009

    View details for PubMedID 20539236

  • Mapping Gene Associations in Human Mitochondria using Clinical Disease Phenotypes PLOS COMPUTATIONAL BIOLOGY Scharfe, C., Lu, H. H., Neuenburg, J. K., Allen, E. A., Li, G., Klopstock, T., Cowan, T. M., Enns, G. M., Davis, R. W. 2009; 5 (4)

    Abstract

    Nuclear genes encode most mitochondrial proteins, and their mutations cause diverse and debilitating clinical disorders. To date, 1,200 of these mitochondrial genes have been recorded, while no standardized catalog exists of the associated clinical phenotypes. Such a catalog would be useful to develop methods to analyze human phenotypic data, to determine genotype-phenotype relations among many genes and diseases, and to support the clinical diagnosis of mitochondrial disorders. Here we establish a clinical phenotype catalog of 174 mitochondrial disease genes and study associations of diseases and genes. Phenotypic features such as clinical signs and symptoms were manually annotated from full-text medical articles and classified based on the hierarchical MeSH ontology. This classification of phenotypic features of each gene allowed for the comparison of diseases between different genes. In turn, we were then able to measure the phenotypic associations of disease genes for which we calculated a quantitative value that is based on their shared phenotypic features. The results showed that genes sharing more similar phenotypes have a stronger tendency for functional interactions, proving the usefulness of phenotype similarity values in disease gene network analysis. We then constructed a functional network of mitochondrial genes and discovered a higher connectivity for non-disease than for disease genes, and a tendency of disease genes to interact with each other. Utilizing these differences, we propose 168 candidate genes that resemble the characteristic interaction patterns of mitochondrial disease genes. Through their network associations, the candidates are further prioritized for the study of specific disorders such as optic neuropathies and Parkinson disease. Most mitochondrial disease phenotypes involve several clinical categories including neurologic, metabolic, and gastrointestinal disorders, which might indicate the effects of gene defects within the mitochondrial system. The accompanying knowledgebase (http://www.mitophenome.org/) supports the study of clinical diseases and associated genes.

    View details for DOI 10.1371/journal.pcbi.1000374

    View details for Web of Science ID 000266214200033

    View details for PubMedID 19390613

  • Clinical and Molecular Heterogeneity in Patients with the CblD Inborn Error of Cobalamin Metabolism JOURNAL OF PEDIATRICS Miousse, I. R., Watkins, D., Coelho, D., Rupar, T., Crombez, E. A., Vilain, E., Bernstein, J. A., Cowan, T., Lee-Messer, C., Enns, G. M., Fowler, B., Rosenblatt, D. S. 2009; 154 (4): 551-556

    Abstract

    To describe 3 patients with the cblD disorder, a rare inborn error of cobalamin metabolism caused by mutations in the MMADHC gene that can result in isolated homocystinuria, isolated methylmalonic aciduria, or combined homocystinuria and methylmalonic aciduria.Patient clinical records were reviewed. Biochemical and somatic cell genetic studies were performed on cultured fibroblasts. Sequence analysis of the MMADHC gene was performed on patient DNA.Patient 1 presented with isolated methylmalonic aciduria, patient 3 with isolated homocystinuria, and patient 2 with combined methylmalonic aciduria and homocystinuria. Studies of cultured fibroblasts confirmed decreased synthesis of adenosylcobalamin in patient 1, decreased synthesis of methylcobalamin in patient 3, and decreased synthesis of both cobalamin derivatives in patient 2. The diagnosis of cblD was established in each patient by complementation analysis. Mutations in the MMADHC gene were identified in all patients.The results emphasize the heterogeneous clinical, cellular and molecular phenotype of the cblD disorder. The results of molecular analysis of the MMADHC gene are consistent with the hypothesis that mutations affecting the N terminus of the MMADHC protein are associated with methylmalonic aciduria, and mutations affecting the C terminus are associated with homocystinuria.

    View details for DOI 10.1016/j.jpeds.2008.10.043

    View details for Web of Science ID 000264808000020

    View details for PubMedID 19058814

  • Inherited disorders affecting mitochondrial function are associated with glutathione deficiency and hypocitrullinemia PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Atkuri, K. R., Cowan, T. M., Kwan, T., Ng, A., Herzenberg, L. A., Herzenberg, L. A., Enns, G. M. 2009; 106 (10): 3941-3945

    Abstract

    Disorders affecting mitochondria, including those that directly affect the respiratory chain function or result from abnormalities in branched amino acid metabolism (organic acidemias), have been shown to be associated with impaired redox balance. Almost all of the evidence underlying this conclusion has been obtained from studies on patient biopsies or animal models. Since the glutathione (iGSH) system provides the main protection against oxidative damage, we hypothesized that untreated oxidative stress in individuals with mitochondrial dysfunction would result in chronic iGSH deficiency. We confirm this hypothesis here in studies using high-dimensional flow cytometry (Hi-D FACS) and biochemical analysis of freshly obtained blood samples from patients with mitochondrial disorders or organic acidemias. T lymphocyte subsets, monocytes and neutrophils from organic acidemia and mitochondrial patients who were not on antioxidant supplements showed low iGSH levels, whereas similar subjects on antioxidant supplements showed normal iGSH. Measures of iROS levels in blood were insufficient to reveal the chronic oxidative stress in untreated patients. Patients with organic acidemias showed elevated plasma protein carbonyls, while plasma samples from all patients tested showed hypocitrullinemia. These findings indicate that measurements of iGSH in leukocytes may be a particularly useful biomarker to detect redox imbalance in mitochondrial disorders and organic acidemias, thus providing a relatively non-invasive means to monitor disease status and response to therapies. Furthermore, studies here suggest that antioxidant therapy may be useful for relieving the chronic oxidative stress that otherwise occurs in patients with mitochondrial dysfunction.

    View details for DOI 10.1073/pnas.0813409106

    View details for Web of Science ID 000264036900054

    View details for PubMedID 19223582

  • Management and quality assurance in the biochemical genetics laboratory. Current protocols in human genetics / editorial board, Jonathan L. Haines ... [et al.] Cowan, T. M., Strovel, E. T. 2008; Chapter 17: Unit 17 7-?

    Abstract

    High-quality biochemical genetics testing is critical for proper diagnosis and management of patients with inborn errors of metabolism. An accurate diagnosis is a prerequisite for proper treatment, ongoing management, and ultimately, for optimal clinical outcome. Quality testing in the biochemical genetics laboratory is managed via adherence to federal regulations that govern clinical laboratory testing. However, because these were not specifically written for biochemical genetics laboratories, a number of professional organizations have developed practice guidelines to address gaps in the federal code. This unit reviews these regulations and guidelines as they apply to quality management of the biochemical genetics laboratory, including test validation, personnel standards, proficiency testing, and overall quality management (including quality assurance, quality control, and quality improvement). It also provides examples of protocols and forms that can be adapted for the documentation of test validation, personnel training, quality control, and quality assurance.

    View details for DOI 10.1002/0471142905.hg1707s59

    View details for PubMedID 18972371

  • Progressive cerebral vascular degeneration with mitochondrial encephalopathy AMERICAN JOURNAL OF MEDICAL GENETICS PART A Longo, N., Schrijver, I., Vogel, H., Pique, L. M., Cowan, T. M., Pasquali, M., Steinberg, G. K., Hedlund, G. L., Ernst, S. L., Gallagher, R. C., Enns, G. M. 2008; 146A (3): 361-367

    Abstract

    MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) is a maternally inherited disorder characterized by recurrent cerebral infarctions that do not conform to discreet vascular territories. Here we report on a patient who presented at 7 years of age with loss of consciousness and severe metabolic acidosis following vomiting and dehydration. She developed progressive sensorineural hearing loss, myopathy, ptosis, short stature, and mild developmental delays after normal early development. Biochemical testing identified metabolites characteristic of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency (hexanoylglycine and suberylglycine), but also severe lactic acidemia (10-25 mM) and, in urine, excess of lactic acid, intermediates of the citric cycle, and marked ketonuria, suggesting mitochondrial dysfunction. She progressed rapidly to develop temporary cortical blindness. Brain imaging indicated generalized atrophy, more marked on the left side, in addition to white matter alterations consistent with a mitochondrial disorder. Magnetic resonance angiography indicated occlusion of the left cerebral artery with development of collateral circulation (Moyamoya syndrome). This process worsened over time to involve the other side of the brain. A muscle biopsy indicated the presence of numerous ragged red fibers. Molecular testing confirmed compound heterozygosity for the common mutation in the MCAD gene (985A>G) and a second pathogenic mutation (233T>C). MtDNA testing indicated that the muscle was almost homoplasmic for the 3243A>T mutation in tRNALeu, with a lower mutant load (about 50% heteroplasmy) in blood and skin fibroblasts. These results indicate that mitochondrial disorders may be associated with severe vascular disease resulting in Moyamoya syndrome. The contribution of the concomitant MCAD deficiency to the development of the phenotype in this case is unclear.

    View details for DOI 10.1002/ajmg.a.31841

    View details for Web of Science ID 000253008300014

  • Acylcarnitine profile analysis GENETICS IN MEDICINE Rinaldo, P., Cowan, T. M., Matern, D. 2008; 10 (2): 151-156

    Abstract

    These Technical Standards and Guidelines were developed primarily as an educational resource for clinical laboratory geneticists to help them provide quality clinical laboratory genetic services. Adherence to these standards and guidelines is voluntary and does not necessarily assure a successful medical outcome. These Standards and Guidelines should not be considered inclusive of all proper procedures and tests or exclusive of other procedures and tests that are reasonably directed to obtaining the same results. In determining the propriety of any specific procedure or test, the clinical laboratory geneticist should apply his or her own professional judgment to the specific circumstances presented by the individual patient or specimen. Clinical laboratory geneticists are encouraged to document in the patient's record the rationale for the use of a particular procedure or test, whether or not it is in conformance with these Standards and Guidelines. They also are advised to take notice of the date any particular standard or guidelines was adopted, and to consider other relevant medical and scientific information that becomes available after that date.

    View details for DOI 10.1097/GIM.0013e3181614289

    View details for Web of Science ID 000253277400011

    View details for PubMedID 18281923

  • Importance of culturing primary lymphocytes at physiological oxygen levels PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Atkuri, K. R., Herzenberg, L. A., Niemi, A., Cowan, T., Herzenberg, L. A. 2007; 104 (11): 4547-4552

    Abstract

    Although studies with primary lymphocytes are almost always conducted in CO(2) incubators maintained at atmospheric oxygen levels (atmosO(2); 20%), the physiological oxygen levels (physO(2); 5%) that cells encounter in vivo are 2-4 times lower. We show here that culturing primary T cells at atmosO(2) significantly alters the intracellular redox state (decreases intracellular glutathione, increases oxidized intracellular glutathione), whereas culturing at physO(2) maintains the intracellular redox environment (intracellular glutathione/oxidized intracellular glutathione) close to its in vivo status. Furthermore, we show that CD3/CD28-induced T cell proliferation (based on proliferation index and cell yield) is higher at atmosO(2) than at physO(2). This apparently paradoxical finding, we suggest, may be explained by two additional findings with CD3/CD28-stimulated T cells: (i) the intracellular NO (iNO) levels are higher at physO(2) than at atmosO(2); and (ii) the peak expression of CD69 is significantly delayed and more sustained at physO(2) that at atmosO(2). Because high levels of intracellular NO and sustained CD69 tend to down-regulate T cell responses in vivo, the lower proliferative T cell responses at physO(2) likely reflect the in vitro operation of the natural in vivo regulatory mechanisms. Thus, we suggest caution in culturing primary lymphocytes at atmosO(2) because the requisite adaptation to nonphysiological oxygen levels may seriously skew T cell responses, particularly after several days in culture.

    View details for DOI 10.1073/pnas.0611732104

    View details for Web of Science ID 000244972700055

    View details for PubMedID 17360561

  • Glutaryl-CoA dehydrogenase deficiency and newborn screening: Retrospective analysis of a low excretor provides further evidence that some cases may be missed MOLECULAR GENETICS AND METABOLISM Gallagher, R. C., Cowan, T. M., Goodman, S. I., Enns, G. A. 2005; 86 (3): 417-420

    Abstract

    Glutaryl-CoA dehydrogenase deficiency (GA-I) is associated with the onset of irreversible, disabling dystonia between 3 and 18 months of age. Presymptomatic identification and treatment can prevent the devastating disability associated with this disorder. We report the retrospective analysis of the newborn blood spot of an affected child with a low excretor phenotype. The level of glutarylcarnitine was below the newborn screening program cut-off. This suggests that some cases of GA-I may be missed by newborn screening by tandem mass spectrometry.

    View details for DOI 10.1016/j.ymgme.2005.08.005

    View details for Web of Science ID 000233327600012

    View details for PubMedID 16183314

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