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At least 19 recordsLinked to original sources
PubMed1978

Glutathione peroxidase in dried blood spots.

A new procedure utilizing dried blood spots was developed for detecting glutathione peroxidase deficiency. Samples from a known patient with a partial defect and from rats with an induced deficiency were distinguished from respective control groups by their longer defluorescence endpoints. Samples from 100 patients with anemia and 2 phenyl-ketonuric infants on low-protein diets contained glutathione peroxidase activity similar to that in 82 controls, when screened for the enzyme defect by the new procedure.

Adult↗
PubMed1978

Micromethod for estimating adenosine deaminase activity in dried blood spots on filter paper.

We describe a fluorometric micromethod for measuring adenosine deaminase activity in dried blood spots on filter paper. Earlier methods require venipuncture and preparation of washed erythrocytes; in the present method, whole capillary blood, spotted on filter paper and mailed (dried) to a central laboratory, is used. The stability of the enzyme in dried blood on filter paper was assessed. The results were compared with those of a spectrophotometric method. The presence of serum appears not to affect the estimation of the activity and the method may be useful in early detection of severe combined immunodeficiency disease and hereditary hemolytic anemia.

Adenosine Deaminase↗
PubMed1975

Measurement of thyroid-stimulating hormone in dried blood spot.

Blood T.S.H. (thyroid-stimulating hormone) was measured by radioimmunoassay in dried blood spotted onto filter-paper and obtained during screening of the newborn for metabolic disorders. By this method, the detection limit for blood T.S.H. was 5--10 muU/ml, which is the approximate upper limit of normal for blood T.S.H. T.S.H. values obtained on dried blood correlated well with those obtained on serum from the same subjects. Duplication of the assay in a single sample is not necessary. This method picked up a case of primary hypothyroidism in a four-year-old girl with symptoms. Since the technique is simple and sensitive enough for the detection of hypothyroidism, it could be valuable in mass-screening for congenital hypothyroidism.

Adult↗
PubMed2026

Evaluation of dried blood spots relative to peripheral blood mononuclear cells for intracellular tenofovir-diphosphate and emtricitabine-triphosphate assessment using liquid chromatography-tandem mass spectrometry.

Tenofovir alafenamide/emtricitabine (TAF/FTC) is widely used for HIV treatment and prevention. Their intracellular metabolites, tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP), provide informative measures of drug exposure. Peripheral blood mononuclear cells (PBMCs) are the primary matrix for these measurements; however, their isolation is labor-intensive, limiting clinical applicability. This study evaluated dried blood spots (DBS) for assessing intracellular TFV-DP and FTC-TP exposure relative to PBMCs. Paired PBMC and DBS samples (n&#x202f;=&#x202f;124) were analyzed using a validated LC-MS/MS method. Moderate correlations were observed between DBS and PBMC concentrations for TFV-DP (r&#x202f;=&#x202f;0.44, p&#x202f;<&#x202f;0.0001) and FTC-TP (r&#x202f;=&#x202f;0.27, p&#x202f;=&#x202f;0.0025), with stronger correlations in the central 80% of participants based on the DBS-to-PBMC concentration ratios (r&#x202f;=&#x202f;0.61 and 0.44, respectively). Log-transformed Bland-Altman analysis, with more than 90% of samples falling within the 95% limits of agreement. Additionally, concentration distributions across different virological statuses were similar between DBS and PBMC. DBS samples (n&#x202f;=&#x202f;44) were also collected at baseline and on day 29 from people with HIV receiving TAF/FTC in combination with isoniazid plus rifapentine (1HP) to demonstrate the applicability of DBS for investigating potential drug-drug interactions (DDIs). In conclusion, the observed moderate correlations between DBS and PBMC concentrations of TFV-DP and FTC-TP suggest that DBS may serve as a feasible sampling approach for population-level assessment of intracellular TFV-DP and FTC-TP exposure. The simplicity of DBS sample collection and handling may facilitate large-scale clinical studies and highlights its potential utility in future clinical research.

Dried blood spots↗
PubMed1979

Measurement of anti-thyroid antibodies in dried blood spots.

The method for determination of anti-thyroid antibodies in extracts of dried whole blood on filter paper was described. Antibodies in dried blood were stable at room temperature for at least 1 month and were extracted well by overnight elution. This simple method requires only a minimal 30 microliter of venous blood and would enable large-scale screening for autoimmune thyroid diseases.

Autoantibodies↗
PubMed1979

Dried-blood spot screening for cystic fibrosis in the newborn.

Serum-immunoreactive-trypsin (I.R.T.) was measured in children with cystic fibrosis (C.F.) and a variety of controls. In the first few months of life all C.F. children had a raised serum-I.R.T. A dried blood-spot assay for I.R.T. was established and has potential as a screening test for C.F. in the newborn.

Antigens↗
PubMedDate not supplied

[Neonatal screening of congenital hypothyroidism with TSH measurement in dried blood spots on filter paper. A two years experience (author's transl)].

Systematic screening for congenital hypothyroidism was started in Lyon in september 1976. This screening was coupled with PKU, using the same dried blood samples on filter paper obtained on the 5th day of life. TSH levels were determined by radioimmunoassay adapted for dried blood samples (Kit Abbott). In 24 months, 56 176 samples were analyzed. The critical level calling for control was successively raised from from 20 to 30, now 40 microUI/ml of serum. A high level of TSH was found in 307 children (0,55%). Pathological deliveries were found in most of these infants (neonatal injury, cesarean, section forceps or ocytocic perfusion, neonatal icterus) and a second or a third measurement showed normal TSH level. Congenital hypothyroidism, was found detected in 18 infants: 12 ectopic gland, 5 athyreosis and 1 dyshormonogenesis. Treatment was begun at a mean age of 38 days (29 to 50 days).

Congenital Hypothyroidism↗
PubMed1979

[Early detection of congenital hypothyroidism by TSH radioimmunoassay using filter paper blood samples (author's transl)].

It has been reported that mental retardation due to congenital hypothyroidism can be prevented by early detection and early adequate replacement therapy. We have developed a radioimmunoassay for TSH using the dried blood spot and have started screening for newborn congenital hypothyroidism using a part of sample of the inborn metabolic error screening. (1) The dried blood spot TSH of 61,000 newborn infants was assayed in the first half of our screening and that of 74,505 newborn infants was assayed in the latter half of our screening. As a result, although we were not able to detect any cases in the first screening, we were able to detect 9 cases of congenital hypothyroidism in the latter screening. From the results obtained through our investigation of the thyroid function of these 9 infants, we confirmed that mild hypothyroidism can be better detected by the screening of TSH. (2) As to the program of the screening, we chose from the latter half of our screening all the samples in which TSH concentrations contained above 3 percent of each assay and were remeasured on the next assay. (3) As we confirmed that the sensitivity of measurement was increased at very low concentrations, when the volume of antibodies, radioisotopes and eluates used for each assay were decreased, we measured TSH successfully using two 3 mm discs. (4) As we can perform very simple screening by the 3 mm disc method, we are changing the screening method from that with 10 mm disc to one with two 3 mm discs. We intend to extend our screening, and will make every effort to prevent mental retardation due to congenital hypothyroidism.

Blood Preservation↗
PubMed2026

Next-generation newborn screening: feasibility of combined genetic and biochemical testing for 95 treatable inherited metabolic disorders.

INTRODUCTION: Next-generation sequencing (NGS) is gaining attention in newborn screening (NBS) for its ability to detect treatable genetic disorders, especially those without a biochemical footprint. However, NGS-NBS requires interpreting variants without phenotype information or family trio analysis. Biochemical tests, preferably in dried blood spots (DBS), are therefore useful to confirm the pathogenicity of variants identified by NGS-NBS and increase its specificity and sensitivity. OBJECTIVES: We aimed to explore the potential of combined genetic-biochemical testing for 95 treatable Inherited Metabolic Disorders (IMD) considered eligible for NGS-NBS (100 genes) previously identified by our research group. METHODS: We reviewed the Collaborative Laboratory Integrated Reports (CLIR) and carried out systematic literature reviews in PubMed and Embase to identify biochemical tests for 95 IMD. Biochemical tests conducted on DBS were differentiated from tests that require referral. RESULTS: We identified DBS-biochemical tests for 72 of the 95 IMD (77/100 genes). DBS-based biochemical tests for 55 IMD (60 genes) are already implemented in NBS. For the other 23 IMD, biochemical tests in non-DBS specimens are reported, although some are less sensitive when measured at neonatal age in presymptomatic infants. CONCLUSION: We present a comprehensive overview of current biochemical tests for 95 IMD. These tests can be used to confirm inconclusive NGS-NBS results, and combined genetic-biochemical testing is expected to improve both the negative and positive predictive values of NBS programs.

Humans↗
PubMed1979

Blood-spot thyrotropin radioimmunoassay in a screening program for congenital hypothyroidism.

We describe a highly sensitive and precise radioimmunoassay for thyrotropin in dried blood spots on filter paper cards. In a screening program for congenital hypothyroidism, blood-spot thyrotropin concentrations are measured in infants whose blood-spot thyroxine concentrations are in the lower 10%, and this strategy has reduced the recall rate from 1.7% (thyroxine assay alone) to 0.17%. Thyrotropin assay samples consist of discs 4.5-mm in diameter, containing about 6 microL of blood, punched from blood spots. By appropriate attention to assay conditions, a mean least-detectable thyrotropin concentration equivalent to 2.5 milliunits/L plasma has been achieved. Concomitant measurement of thyrotropin by plasma and blood-spot assays in 91 subjects yielded a Spearman rank correlation coefficient of 0.9732. An analysis of variance of the distribution volume of thyrotropin in blood spots and a covariance analysis of factors affecting blood-spot thyroxine results are presented.

Birth Weight↗
PubMed2026

Exploring hormonal influences on nicotine craving and use across the perinatal period: A prospective longitudinal study.

INTRODUCTION: Perinatal nicotine use is common despite well-documented adverse consequences. We examined associations between reproductive-related hormones with nicotine craving and use during the perinatal period to identify potential novel intervention points. METHODS: All participants reported use of nicotine during the perinatal period. Participants were enrolled at gestational week &#x2265;&#x2009;36 and followed to postpartum week 12 via daily surveys (i.e., nicotine craving via 100-point scale, dichotomous use) and weekly hormone measurement in saliva (cortisol, oxytocin) or dried blood spots (progesterone, estradiol, testosterone, dehydroepiandrosterone sulfate). Bayesian mixed-effects models accounted for within-person correlation while estimating hormone effects. RESULTS: Participants (n&#x2009;=&#x2009;46) were 28.9&#x2009;&#xb1;&#x2009;4.9 years old. During follow-up, exclusive combustible cigarettes (n&#x2009;=&#x2009;20), electronic nicotine delivery systems (ENDS; n&#x2009;=&#x2009;13), or dual (n&#x2009;=&#x2009;2) use was observed, with variability in use and craving across participants and over time. During pregnancy, higher oxytocin was linked to greater craving (&#x3b2;=16.31, 95% CI: 3.71, 28.83). Greater peripartum declines in oxytocin were associated with more craving (&#x3b2;=8.71, 95% CI: 0.75, 16.93) and use (&#x3b2;=1.13, 95% CI: 0.05, 2.43). During postpartum, lower estradiol was linked to more craving (&#x3b2;=-1.17, 95% CI: -2.15, -0.18) and use (&#x3b2;=-0.40, 95% CI: -0.76, -0.03). In models simultaneously evaluating all postpartum hormones, the lone meaningful association was between estradiol and craving (&#x3b2;=-1.66, 95% CI: -2.84, -0.48). CONCLUSIONS: The results of this study suggest that oxytocin and estradiol may contribute to the risk of perinatal nicotine use. Additional research is needed to replicate our observations in more diverse study samples and explore implications for clinical intervention.

Bayesian↗
PubMed2025

Newborn screening for common genetic variants associated with permanent hearing loss: Implementation in Ontario and review of the first 3&#xa0;years.

PURPOSE: Early hearing detection and intervention (EHDI) programs using audiometric screening techniques alone have a limited ability to detect noncongenital childhood permanent hearing loss (PHL). In 2019, Ontario launched universal newborn screening (NBS) for PHL risk factors, including congenital cytomegalovirus and 22 common variants in GJB2 and SLC26A4. Here, we describe our experience in screening for genetic risk factors. METHODS: Ontario newborns who participated in universal newborn hearing screening (UNHS) were offered risk factor screening using dried blood spots (DBS) collected for conventional newborn screening. The screening was conducted using a custom MassArray assay, and positive results were confirmed by Sanger sequencing or polymerase chain reaction. Diagnostic audiological assessments were performed for all screen-positive infants. RESULTS: Of the 412,424 infants screened, 93 had 2 variants in GJB2 or SLC26A4. Of these, 72 had confirmed PHL, 20 had normal hearing, and 1 declined follow-up. Thirteen infants with PHL (1 in 31,724; 11.8% of screen positives) were not identified through audiometric testing as they passed (3) or missed (10) the screening. Importantly, among infants who ultimately received cochlear implants, the detection of genetic etiology through NBS led to an accelerated time to diagnosis, assessment, and intervention. CONCLUSION: Genetic screening has strengthened UNHS and care for infants with or at risk of PHL in Ontario. This study is a step toward the broader inclusion of genomic testing in NBS.

Humans↗
PubMed2025

Comprehensive genotypic, phenotypic, and biochemical characterization of GOT2 deficiency: A progressive neurodevelopmental disorder with epilepsy and abnormal movements.

PURPOSE: Glutamic-oxaloacetic transaminase (GOT), also known as aspartate aminotransferase, catalyzes the reversible transamination of oxaloacetate and glutamate to aspartate and &#x3b1;-ketoglutarate. Two isoforms, cytosolic (GOT1) and mitochondrial (GOT2), are integral to the malate-aspartate shuttle, a key regulator of intracellular redox homeostasis. Recently, 5 patients with biallelic variants in GOT2 were described, presenting with developmental and epileptic encephalopathy. METHODS: We report 11 additional patients with homozygous GOT2 variants, along with additional data from 4 previously reported patients. Through genetic, clinical, and biochemical analyses, we further characterize the phenotypic spectrum of GOT2 deficiency. RESULTS: Most patients exhibited progressive neurodevelopmental delay, severe to profound intellectual disability, infantile epilepsy, progressive microcephaly, and hypotonia evolving into spasticity with axial hypotonia. Dysmorphic features included narrow foreheads, broad nasal tips, and tall or pointed chins. Neuroimaging revealed 2 severity groups based on cerebral volume loss and myelination defects. Thinning of the corpus callosum and white matter abnormalities were common. Biochemical profiling identified low aspartate and high glycerol-3-phosphate in dried blood spots as potential screening markers. Patient fibroblast cells showed reduced serine and glycine biosynthesis, rescuable by pyruvate supplementation. CONCLUSION: These findings expand the phenotypic spectrum of GOT2 deficiency, establish it as a cause of developmental epileptic encephalopathy, and propose novel biomarkers for diagnosis and treatment.

Humans↗
PubMed1979

Sensitive trypsin assay for dried-blood specimens as a screening procedure for early detection of cystic fibrosis.

An immunoreactive-trypsin assay uses small dried-blood spots (diameter 1.25 mm) and is therefore suitable for incorporation in established neonatal screening schemes. Blood specimens from neonates with cystic fibrosis had trypsin levels greater than those in control subjects, thus confirming earlier findings. Trypsin levels were below normal in several older patients with cystic fibrosis.

Adolescent↗
PubMed2026

A prospective pharmacokinetic interaction study between rifampicin and fusidic acid for the treatment of staphylococcal infections.

OBJECTIVE: Fusidic acid with rifampicin is used for the treatment of severe staphylococcal infection, particularly prosthetic joint infections. Previous studies using twice daily fusidic acid showed rifampicin increases fusidic acid clearance, potentially causing sub-therapeutic concentrations. It is uncertain whether this occurs with three-times daily dosing. This study sought to re-evaluate this potential drug-drug interaction. METHODS: In this prospective, open-label drug-drug interaction population pharmacokinetic (PK) study, participants were randomized to receive fusidic acid or rifampicin for 24&#x2005;hours, followed by combination therapy for the duration of treatment. Drug concentration assays used liquid-chromatography mass spectroscopy on dried blood spots. Population PK models were built for fusidic acid, rifampicin and 25-desacetyl rifampicin. RESULTS: Ten participants were recruited. Inter-individual variability for both absorption (98.1%) and clearance (77.8%) were high for fusidic acid. A population pharmacokinetic model for fusidic acid revealed that early autoinhibition dominated over later rifampicin-mediated induction, resulting in a net decrease in fusidic acid clearance. The mean fusidic acid area under the curve during each dosing interval (AUC&#x3c4;) at steady state was 1.76-fold [0.049, 34.918] higher relative to Day 1, despite high uncertainty.Large inter-individual (110%) variability in absorption was observed for rifampicin. There was no apparent effect on rifampicin metabolism by fusidic acid co-administration, however, fusidic acid decreased clearance of 25-desacetyl rifampicin. CONCLUSION: In patients treated with fusidic acid three times daily in combination with rifampicin, autoinhibition potentially counteracted rifampicin induction such that fusidic acid concentrations were not reduced. Rifampicin clearance was not affected by fusidic acid, but 25-desacetyl rifampicin clearance was decreased. There was large inter-individual variability in the observed concentrations and final parameter estimates.

Fusidic Acid↗