Retrospective Review of Positive Newborn Screening Results for Isovaleric Acidemia and Development of a Strategy to Improve the Efficacy of Newborn Screening in the UK.

Since the UK commenced newborn screening for isovaleric acidemia in 2015, changes in prescribing have increased the incidence of false positive (FP) results due to pivaloylcarnitine. A review of screening results between 2015 and 2022 identified 24 true positive (TP) and 84 FP cases, with pivalate interference confirmed in 76/84. Initial C5 carnitine (C5C) did not discriminate between FP and TP with median (range) C5C of 2.9 (2.0-9.6) and 4.0 (1.8->70) µmol/L, respectively, and neither did Precision Newborn Screening via Collaborative Laboratory Integrated Reports (CLIR), which identified only 1/47 FP cases. However, among the TP cases, disease severity showed a correlation with initial C5C in 'asymptomatic' individuals (n = 17), demonstrating a median (range) C5C of 3.0 (1.8-7.1) whilst 'clinically affected' patients (n = 7), showed a median (range) C5C of 13.9 (7.7-70) µmol/L. These findings allowed the introduction of dual cut-off values into the screening algorithm to reduce the incidence of FPs, with initial C5C results ≥ 5 µmol/L triggering urgent referral, and those >2.0 and <5.0 µmol/L prompting second-tier C5-isobar testing. This will avoid delayed referral in babies at particular risk whilst reducing the FP rate for the remainder.

A computer vision approach to the assessment of dried blood spot size and quality in newborn screening.

BACKGROUND: Dried blood spot (DBS) size and quality affect newborn screening (NBS) test results. Visual assessment of DBS quality is subjective. METHODS: We developed and validated a computer vision (CV) algorithm to measure DBS diameter and identify incorrectly applied blood in images from the Panthera DBS puncher. We used CV to assess historical trends in DBS quality and correlate DBS diameter to NBS analyte concentrations in 130,620 specimens. RESULTS: CV estimates of DBS diameter were precise (percentage coefficient of variation < 1.3%) and demonstrated excellent agreement with digital calipers with a mean (standard deviation) difference of 0.23 mm (0.18 mm). An optimised logistic regression model showed a sensitivity of 94.3% and specificity of 96.8% for detecting incorrectly applied blood. In a validation set of images (n = 40), CV agreed with an expert panel in all acceptable specimens and identified all specimens rejected by the expert panel due to incorrect blood application or DBS diameter > 14 mm. CV identified a reduction in unsuitable NBS specimens from 25.5% in 2015 to 2% in 2021. Each mm decrease in DBS diameter decreased analyte concentrations by up to 4.3%. CONCLUSIONS: CV can aid assessment of DBS size and quality to harmonize specimen rejection both within and between laboratories.

Amino Acids in Health and Endocrine Function.

Dietary amino acids play an important role in maintaining health. Branched chain amino acids can adversely increase blood pressure whereas arginine and citrulline can reduce it. D-amino acids play important roles in several cell types including testis, the nervous system and adrenal glands. Several amino acids also can have dramatic effects on diabetes; branched chain amino acids, phenylalanine and tyrosine have been implicated while others, namely arginine and citrulline can improve outcomes. Leucine has been shown to play important roles in muscle primarily through the mTOR pathway though this effect does not translate across every population. Glutamine, arginine and D-aspartate also exert their muscle effects through mTOR. Relationships between amino acids and endocrine function include that of glucocorticoids, thyroid function, glucagon-like peptide 1 (GLP-1), ghrelin, insulin-like growth factor-1 (IGF-1) and leptin. Leucine, for example, can alleviate the effect of dexamethasone on muscle protein accretion. Interestingly, amino acid transporters play an important role in thyroid function. Several amino acids have been shown to increase GLP-1 levels in non-diabetics when administered orally. Similarly, several amino acids increase ghrelin levels in different species while cysteine can decrease it in mice. There is evidence to suggest that the arginine/NO pathway may be involved in modulating some of the effects of ghrelin on cells. In regard to IGF-1, branched chain amino acids can increase levels in adults while tryptophan and phenylalanine have been shown to increase levels in infants. Finally, leptin levels can be elevated by branched chain amino acids while restricting leucine in high fat diets can increase leptin sensitivity.

Chemistry of Aged Beer and Spirits: Symposium Introduction.

The Chemistry of Aged Beer and Spirits Symposium was organized at the American Chemical Society (ACS) Fall 2019 National Meeting & Exposition, San Diego, CA, U.S.A. in August 2019 with a keynote address, three informational talks, and six research-based talks. Beer-related topics ranged from the sensory compounds associated with barrel aging to haze formation, to wood aging, and finally to in-line detection of diacetyl. Topics on spirits ranged from the chemistry of tequila to effects of water components on whiskey to analysis of whiskey microwebs. The symposium was well-attended and supplemented with an introduction to brewing processes at a local brewery.

Olive ingestion causing a false suspicion of relapsed neuroblastoma: A case of "oliveblastoma?"

Measurement of the urine catecholamine metabolites homovanillic acid (HVA) and vanillylmandelic acid (VMA) are the standard method for detecting disease recurrence in neuroblastoma. We present a case of abnormal concentrations of catecholamine metabolites that prompted investigations for relapsed neuroblastoma. However, further study revealed that the abnormal biochemistry was likely due to ingestion of olives. Olive ingestion should be considered when interpreting urine HVA and VMA results, and excluded if concentrations are unexpectedly abnormal.

Acrylamide in health and disease.

Acrylamide has been classified as a probable carcinogen and can be ingested, inhaled (e.g. tobacco smoke), or absorbed. Fried, starchy foods are the most prominent sources of exposure. The reaction between asparagine and fructose typically produces the most acrylamide in foods from plant sources. Preparation methods shown to affect acrylamide production include temperature and cooking oil. Hemoglobin adducts present a reliable short term measurement of acrylamide exposure; a variety of methods, predominately LC/MS-MS, have been used for acrylamide detection. Health effects of acrylamide include neurotoxicity and genotoxicity. It is believed that the electrophilic nature of acrylamide will allow it to adduct to thiol groups on nerve axons and proteins that regulate neurotransmitter exocytosis. Presynaptic nitric oxide (NO) may also play a role here. Reproductively, males demonstrate a decrease in sperm count, motility and morphology. Acrylamide produces clastogenic effects while glycidamide (GA), its metabolite, produces mutagenic effects. A number of protective measures against the effects of acrylamide are possible including probiotics, increased use of compounds known to decrease acrylamide production and bioengineering of precursor foods such as potatoes.

Glycine oxidation and conversion into amino acids in Saccharomyces cerevisiae and Candida albicans.

Humans are exposed much more often to exogenous Saccharomyces cerevisiae (a baker's yeast) than exogenous Candida albicans (a highly infectious yeast) but suffer no apparent complications from S. cerevisiae. We hypothesize that variations in characteristics between these two species may be due, in part, to differences in glycine metabolism. In this study, we examined differences in glycine oxidation between C. albicans and S. cerevisiae. Both C. albicans and S. cerevisiae were cultured in glycine enriched media, followed by determination of glycine oxidation and amino acid concentrations in cells. Glycine was degraded to a much greater extent in C. albicans than in S. cerevisiae. Threonine concentrations and glycine oxidation were also elevated in C. albicans. Almost all of the disappearance of glycine from incubation media was accounted for by the formation of serine, threonine, and CO(2) in S. cerevisiae, whereas these products represented only 50% of the metabolized glycine in C. albicans. The unidentified metabolites of glycine in C. albicans, presumably purines, could contribute to its infectious capacity and this warrants further study.

L-Glutamine or L-alanyl-L-glutamine prevents oxidant- or endotoxin-induced death of neonatal enterocytes.

This study tested the hypothesis that L-glutamine (Gln) or L-alanyl-L-glutamine (Ala-Gln) prevents oxidant- or endotoxin-induced death of neonatal enterocytes. Enterocytes of neonatal pigs rapidly hydrolyzed Ala-Gln and utilized Gln. To determine whether Gln or Ala-Gln has a cytoprotective effect, IPEC-1 cells were cultured for 24 h in Gln-free Dulbecco's modified Eagle's-F12 Ham medium containing 0, 0.5, 2.0 or 5.0 mM Gln or Ala-Gln, and 0, 0.5 mM H(2)O(2) or 30 ng/ml lipopolysaccharide (LPS). Without Gln or Ala-Gln, H(2)O(2)- or LPS-treated cells exhibited almost complete death. Gln or Ala-Gln at 0.5, 2 and 5 mM dose-dependently reduced H(2)O(2)- or LPS-induced cell death by 14, 54 and 95%, respectively, whereas D: -glutamine, alanine, glutamate, ornithine, proline, glucosamine or nucleosides had no effect. To evaluate the effectiveness of Gln or Ala-Gln in vivo, 7-day-old piglets received one-week oral administration of Gln or Ala-Gln (3.42 mmol/kg body weight) twice daily and then a single intraperitoneal injection of LPS (0.1 mg/kg body weight); piglets were euthanized in 24 and 48 h to analyze intestinal apoptotic proteins and morphology. Administration of Gln or Ala-Gln to LPS-challenged piglets increased Gln concentrations in small-intestinal lumen and plasma, reduced intestinal expression of Toll-like receptor-4, active caspase-3 and NFkB, ameliorated intestinal injury, decreased rectal temperature, and enhanced growth performance. These results demonstrate a protective effect of Gln or Ala-Gln against H(2)O(2)- or LPS-induced enterocyte death. The findings support addition of Gln or Ala-Gln to current Gln-free pediatric amino acid solutions to prevent intestinal oxidative injury and inflammatory disease in neonates.

Glucocorticoid regulation of amino acid and polyamine metabolism in the small intestine.

Several factors (including diets, changes in intestinal fluora, and hormones) regulate postnatal intestinal growth and development. Based on the early studies involving modification of the adrenal gland, pituitary gland or hypothalamus, exogenous glucocorticoids and glucocorticoid receptor antagonists are now used to study glucocorticoid-mediated metabolism of amino acids in the small intestine. Findings from these studies indicate that physiological levels of glucocorticoids stimulate the catabolism of glutamine and proline for the synthesis of citrulline and arginine in enterocytes during weaning. In addition, increases in circulating levels of glucocorticoids enhance expression of arginase, proline oxidase and ornithine decarboxylase, as well as polyamine synthesis from arginine and proline in enterocytes. These actions of the hormones promote intestinal maturation and may have therapeutic effects on intestinal disease (e.g., necrotizing enterocolitis). Molecular aspects, species-specific effects, and developmental responsiveness to glucocorticoids should be taken into consideration in designing both experimental and clinical studies.