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This scoping review aimed to synthesize the analytical techniques used and methodological limitations encountered when undertaking secondary research using residual neonatal dried blood spot (DBS) samples. Studies that used residual neonatal DBS samples for secondary research (i.e. research not related to newborn screening for inherited genetic and metabolic disorders) were identified from six electronic databases: Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Embase, Medline, PubMed and Scopus. Inclusion was restricted to studies published from 1973 and written in or translated into English that reported the storage, extraction and testing of neonatal DBS samples. Sixty-seven studies were eligible for inclusion. Included studies were predominantly methodological in nature and measured various analytes, including nucleic acids, proteins, metabolites, environmental pollutants, markers of prenatal substance use and medications. Neonatal DBS samples were stored over a range of temperatures (ambient temperature, cold storage or frozen) and durations (two weeks to 40.5 years), both of which impacted the recovery of some analytes, particularly amino acids, antibodies and environmental pollutants. The size of DBS sample used and potential contamination were also cited as methodological limitations. Residual neonatal DBS samples retained by newborn screening programs are a promising resource for secondary research purposes, with many studies reporting the successful measurement of analytes even from neonatal DBS samples stored for long periods of time in suboptimal temperatures and conditions. [ABSTRACT FROM AUTHOR]

Objective: Necrotizing enterocolitis (NEC) is the leading cause of death among premature infants, and there is a lack of specific early diagnostic markers. Blood sampling is expected to better reflect pathophysiological and metabolic changes in systematic illness, but there is a risk of iatrogenic anemia, especially in premature infants. Dried blood spots technique seems to have important advantages compared to whole blood sampling as it requires only 12–15 μL as sample volume. This study aimed to investigate the special metabolomics of preterm neonates at high risk of NEC using dried blood spots. Methods: Cases and controls were strictly matched 1:1. Dried blood spots (n = 32, 16 cases–16 controls) from newborn screening were subjected to LC–MS/MS. Metabolomic data were analyzed by orthogonal partial least squares-discriminant analysis (OPLS-DA) and univariate/multivariate statistical analysis. Results: Compared to the control group, the NEC group had a significant reduction in seven amino acids (glycine, alanine, threonine, proline, ornithine, lysine, and asparagine). Conclusions: The metabolic profile of neonates with NEC differs significantly from that of controls, making possible their separation with the use of targeted (LC–MS/MS) dried blood spots-based metabolomic analysis. Seven specific markers were identified for early detection and intervention. [ABSTRACT FROM AUTHOR]

Nitazenes represent a new synthetic opioids sub-class belonging to new psychoactive substances (NPSs). Their high pharmacological potency has led to numerous intoxications and fatalities, even at minimum doses. The aim of this study was to assess the stability of four nitazenes (etazene, flunitazene, isotonitazene and protonitazene) in dried blood spot (DBS) samples at different storage temperatures (room temperature and 4 °C) and determine the optimal storage conditions. Moreover, we developed and validated a new and fast liquid chromatography–high-resolution mass spectrometry method by the optimization of chromatographic conditions with the use of a different chromatographic column and mobile phases. Two concentrations, 1 and 5 ng/mL, were chosen based on the available data on nitazenes-related intoxications and their stability was evaluated at days 0 (control), 1, 7 and 30. The results showed that all analytes at 1 ng/mL were not detectable after 30 days at room temperature; a similar pattern was observed for 1 ng/mL etazene and isotonitazene samples when stored at 4 °C, whereas flunitazene and protonitazene decreased to a mean of 66% and 69% initial concentrations, respectively, at day 30. Differently, all analytes at 5 ng/mL were quantified above 44% and 41% initial concentrations at room temperature and 4 °C, respectively, showing a higher stability. The study of nitazenes stability in DBSs represents an important tool to determine the optimal sample storage conditions, such as temperature and time between sample collection and analysis. In contrast to another study, our study showed distinct stability behaviors for every investigated analyte, which also depended on the concentration. Therefore, it is difficult to define an optimal storage condition acceptable for all nitazenes. Room temperature proved to be the best medium- and long-term storage conditions for the highest concentrations, but the stability of low levels of flunitazene and protonitazene improved at 4 °C. [ABSTRACT FROM AUTHOR]

Background QUANTI-TAF aimed to establish tenofovir-diphosphate (TFV-DP)/emtricitabine-triphosphate (FTC-TP) adherence benchmarks in dried blood spots (DBS) for persons with human immunodeficiency virus (PWH) receiving tenofovir alafenamide/emtricitabine (TAF/FTC)–based antiretroviral therapy (ART). Methods For 16 weeks, PWH received TAF/FTC-based ART co-encapsulated with an ingestible sensor to directly measure cumulative (enrollment to final visit) and 10-day adherence. At monthly visits, intraerythrocytic concentrations of TFV-DP and FTC-TP in DBS were quantified and summarized at steady-state (week 12 or 16) as median (interquartile range). Linear mixed-effects models evaluated factors associated with TFV-DP/FTC-TP. Results Eighty-four participants (11% female, 4% transgender) predominantly receiving bictegravir/TAF/FTC (73%) were enrolled. Ninety-two percent completed week 12 or 16 (94% unboosted ART). TFV-DP for <85% (7/72), 85%–<95% (9/72), and ≥95% (56/72) cumulative adherence was 2696 (2039–4108), 3117 (2332–3339), and 3344 (2605–4293) fmol/punches. Adjusting for cumulative adherence, TFV-DP was higher with boosted ART, lower body mass index, and in non-Black participants. FTC-TP for <85% (14/77), 85%–<95% (6/77), and ≥95% (57/77) 10-day adherence was 3.52 (2.64–4.48), 4.58 (4.39–5.06), and 4.96 (4.21–6.26) pmol/punches. All participants with ≥85% cumulative and 10-day adherence had TFV-DP ≥1800 fmol/punches and FTC-TP ≥2.5 pmol/punches, respectively. Low-level viremia (HIV-1 RNA 20–199 copies/mL) occurred at 18% of visits in 39% of participants with similar TFV-DP (3177 [2494–4149] fmol/punches) compared with suppressed visits (3279 [2580–4407] fmol/punches). Conclusions TFV-DP ≥1800 fmol/punches and FTC-TP ≥2.5 pmol/punches represent DBS benchmarks for ≥85% adherence to unboosted TAF/FTC-based ART. Among PWH with high adherence, low-level viremia was common. Clinical Trials Registration NCT04065347. [ABSTRACT FROM AUTHOR]

Dried blood spot (DBS) technique has become a new popular topic in anti-doping field in recent years due to its advantages of sample stability and easy operation. It can be employed as a supplementary method to routine urine analysis. However, the small volume of DBS samples (usually 10–20 μL) significantly reduces the application value of this technique. Therefore, the development of sensitive detection methods for the analysis of prohibited substances in DBS is particularly important. In this study, based on the characteristics of low molecular mass peptide (LMMP) drugs, systematic optimization strategies were utilized for the first time to establish a sensitive detection method for LMMPs in DBS. Without using DMSO to enhance mass spectrometry ionization efficiency of peptides, the limits of detection (LOD) ranged between 0.05 and 3.74 ng/mL, significantly better than the previously reported method (0.5–20 ng/mL). This method was validated according to the guidelines of the World Anti-Doping Agency (WADA), and corresponding post-administration study was conducted, demonstrating that the method could be applied to routine analysis of LMMP drugs in DBS. Moreover, since DMSO is not involved, this method also has the potential to simultaneously detect both LMMP and small molecular drugs. [ABSTRACT FROM AUTHOR]

INTRODUCTION: The apolipoprotein E (APOE) ε4 allele carries risk for cognitive impairment, but whether the level of circulating apoE4 protein in carriers affects cognition is unclear, as is how health and lifestyle impact circulating apoE4 levels. METHODS: We assayed apoE4 protein levels in dried blood spots of 12,532 adults aged 50+. Regression analyses tested the likelihood of cognitive impairment between groups and within those with detected apoE4 protein. Predictors of circulating apoE4 were assessed. RESULTS: We detected protein binding that indicates the presence of an APOE ε4 allele in 28.4% of this group. This group was more likely to have cognitive impairment, and this risk increases with age. However, higher apoE4 levels were associated with less likelihood of cognitive impairment within this group. Antihypertensive medication predicted apoE4 protein levels. DISCUSSION: The apoE4 isoform is associated with a deficient protein and worse cognition. This association is modulated by the level of circulating apoE4 protein in ε4 carriers. Highlights: An assay to quantify apoE4 levels from dried blood spot samples was applied.The apoE4 protein was detected as specific binding at ≥30,000 pg/mL in 28.4% of samples.Having the apoE4 protein was associated with worse cognitive performance.Higher apoE4 protein levels in those who have it were associated with better cognition.Cardiovascular factors influenced levels of apoE4 protein. [ABSTRACT FROM AUTHOR]

Dried blood spots (DBSs) are formed by collecting a small sample of blood on specialized filter paper and allowing it to dry naturally. Various domains of life sciences and drug research extensively use DBSs as a sampling technique. The "Hematocrit (Ht) effect" affects assay bias, and several strategies have been put forth to deal with it, including the correction of quantified concentrations using an appropriate correction factor. The approach was previously applied, following the utilization of an image processing algorithm developed in Matlab® to derive a reliable equation correlating DBS areas to Ht% values. The present work looks more closely at the application of image analysis to the evaluation of Ht in DBS samples. Utilizing image analysis software, DBS samples with known Ht values were processed. Preparation of cards has followed a previously developed protocol for the appropriate formation of uniform area DBSs, irrespective of Ht. The resulting areas showed close resemblance to the respective theoretical areas calculated by applying the correlation equation. Following that, the equation was utilized to determine the Ht values for each sample, and a comprehensive comparison of measured versus calculated Ht was carried out using various statistical approaches for method comparison. The results demonstrated a strong correlation, suggesting the method's viability in estimating Ht for unknown DBS samples. [ABSTRACT FROM AUTHOR]

Background: Newborn screening programmes offer an opportunity to obtain dried blood spots (DBS) cards that contain a wealth of biological information that can be stored for long periods and have potential benefits for research and quality assurance. However, the storage and secondary uses of DBS cards pose numerous ethical, clinical, and social challenges. Empirical research exploring public attitudes is central to public policy planning as it can indicate whether or not there is broad public support, define public concerns, and ascertain the circumstances required to alleviate concerns and ensure support. This study aims to describe the clinical experience and attitudes towards newborn screening and investigate the perceptions and expectations of Hong Kong parents and healthcare providers regarding the retention of DBS cards and their usage for research. Methods: We conducted semi-structured in-person interviews with 20 parents and healthcare providers in Hong Kong. Thematic analysis was conducted. Results: Awareness of the significant research value of secondary uses of dried blood spot cards is low. Parents and healthcare providers support the storage and secondary uses of DBS cards with some concerns, including privacy and confidentiality breaches, the risk of discrimination or stigmatisation based on genetic information, and their inability to oversee the use of their child's biospecimen. Parents, however, prioritise their child's health over privacy concerns and support identifiable storage using pseudonymity to gain more information about their children's health. Conclusion: Child information takes precedence over potential concerns over privacy, underscoring the significance of engaging patients and the public in shaping public policy related to biobanking and healthcare research, in line with cultural and social values. [ABSTRACT FROM AUTHOR]

Piperacillin is commonly used off‐label in neonates for the treatment of bacterial infections. This study aimed to assess a dried blood spots (DBS)‐based microsampling strategy for supporting population pharmacokinetics and treatment optimization of piperacillin in Chinese neonates. DBS samples from neonatal patients were collected at predefined intervals. Drug blood concentrations were quantified using a validated ultra‐high‐performance liquid chromatography‐tandem mass spectrometry method. A population pharmacokinetic model was developed using a nonlinear mixed‐effects modeling approach. The pharmacokinetic/pharmacodynamics (PK/PD) target was 75% of the time with the unbound drug plasma concentration above the minimum inhibitory concentration (fT>MIC), with a toxicity threshold of unbound drug plasma trough concentration above 64 mg/L. A total of 45 piperacillin samples from 24 neonates were collected. The pharmacokinetics of piperacillin was described using a one‐compartment model with postmenstrual age (PMA) as the most significant covariate on clearance. Simulations showed that dosing regimens achieving >90% PK/PD target attainment with <10% risk of possible toxicity were: PMA 33‐35 weeks (50 mg/kg q12h), 35‐37 weeks (50 mg/kg q8h), and 37‐41 weeks (50 mg/kg q6h). In conclusion, Using DBS sampling, we developed a population pharmacokinetic model of piperacillin in Chinese neonates, incorporating PMA to determine optimal dosing regimens. [ABSTRACT FROM AUTHOR]

Abstract Background Newborn screening programmes offer an opportunity to obtain dried blood spots (DBS) cards that contain a wealth of biological information that can be stored for long periods and have potential benefits for research and quality assurance. However, the storage and secondary uses of DBS cards pose numerous ethical, clinical, and social challenges. Empirical research exploring public attitudes is central to public policy planning as it can indicate whether or not there is broad public support, define public concerns, and ascertain the circumstances required to alleviate concerns and ensure support. This study aims to describe the clinical experience and attitudes towards newborn screening and investigate the perceptions and expectations of Hong Kong parents and healthcare providers regarding the retention of DBS cards and their usage for research. Methods We conducted semi-structured in-person interviews with 20 parents and healthcare providers in Hong Kong. Thematic analysis was conducted. Results Awareness of the significant research value of secondary uses of dried blood spot cards is low. Parents and healthcare providers support the storage and secondary uses of DBS cards with some concerns, including privacy and confidentiality breaches, the risk of discrimination or stigmatisation based on genetic information, and their inability to oversee the use of their child’s biospecimen. Parents, however, prioritise their child’s health over privacy concerns and support identifiable storage using pseudonymity to gain more information about their children's health. Conclusion Child information takes precedence over potential concerns over privacy, underscoring the significance of engaging patients and the public in shaping public policy related to biobanking and healthcare research, in line with cultural and social values.

• High anti-CMV and anti-mycoplasma IgG at birth increases odds for later ADHD. • This risk-estimate survived adjustment for ADHD-PRS and penicillin prescriptions. • More positive anti-microbial markers increase the odds for later ADHD. • Suggestion: An activated immune system prior to/at birth increases risk for ADHD. Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder typically detected in childhood. Although ADHD has been demonstrated to have a strong genetic component, environmental risk factors, such as maternal infections during pregnancy, may also play a role. We therefore measured the immunological response to 5 abundant microorganisms (Toxoplasmosis Gondii , cytomegalovirus (CMV), Herpes Simplex Virus 1, Epstein Barr Virus and mycoplasma pneumoniae) in newborn heel prick samples of 1679 ADHD cases and 2948 matching controls as part of the iPSYCH Danish case-cohort study. We found an association between high anti-CMV (OR 1.30, 95 % CI [1.09,1.55], p = 0.015) and anti-mycoplasma (OR 1.30, 95 % CI [1.07,1.59], p = 0.037) signal and those newborns later being diagnosed with ADHD. The risk estimate remained increased when controlling for ADHD polygenic risk score as well as penicillin prescriptions. We saw a dose–response association with the amount of positive anti-microorganism titers increasing the risk of being diagnosed with ADHD later in life (p = 0.01 for the trend), suggesting that the more activated the immune system is prior to or at birth, the higher the risk is for a later diagnosis with ADHD. If the associations are causal, they emphasize the importance of a healthy life style during pregnancy to reduce the risk of infections when pregnant and the associated risks for the child. [ABSTRACT FROM AUTHOR]

Abstract Background Although behavioral interventions show some promise for reducing stimulant use and achieving durable viral suppression in sexual minority men (SMM) with HIV, scalable mHealth applications are needed to optimize their reach and cost-effectiveness. Methods Supporting Treatment Adherence for Resilience and Thriving (START) is a randomized controlled trial (RCT) testing the efficacy and cost-effectiveness of a mHealth application that integrates evidence-based positive affect regulation skills with self-monitoring of adherence and mood. The primary outcome is detectable HIV viral load (i.e., > 300 copies/mL) from self-collected dried blood spot (DBS) specimens at 6 months. Secondary outcomes include detectable DBS viral load at 12 months, self-reported stimulant use severity, anti-retroviral therapy (ART) adherence, and positive affect over 12 months. A national sample of up to 250 SMM with HIV who screen positive for stimulant use disorder and reporting suboptimal ART adherence is being recruited via social networking applications through April of 2024. After providing informed consent, participants complete a run-in period (i.e., waiting period) including two baseline assessments with self-report measures and a self-collected DBS sample. Those who complete the run-in period are randomized to either the START mHealth application or access to a website with referrals to HIV care and substance use disorder treatment resources. Participants provide DBS samples at baseline, 6, and 12 months to measure HIV viral load as well as complete self-report measures for secondary outcomes at quarterly follow-up assessments over 12 months. Discussion To date, we have paid $117,500 to advertise START on social networking applications and reached 1,970 eligible participants ($59.77 per eligible participant). Although we identified this large national sample of potentially eligible SMM with HIV who screen positive for a stimulant use disorder and report suboptimal ART adherence, only one-in-four have enrolled in the RCT. The run-in period has proven to be crucial for maintaining scientific rigor and reproducibility of this RCT, such that only half of consented participants complete the required study enrollment activities and attended a randomization visit. Taken together, findings will guide adequate resource allocation to achieve randomization targets in future mHealth research SMM with HIV who use stimulants. Trial Registration This protocol was registered on clinicaltrials.gov (NCT05140876) on December 2, 2021.

This case-control study explored cumulative tenofovir exposure among patients with human immunodeficiency virus/hepatis B virus (HIV/HBV) coinfection with HIV viral suppression. Among patients taking tenofovir disoproxil fumarate, median TFV-DP levels in dried blood spots were ∼3-fold lower among patients with incomplete HBV viral suppression (n = 4) compared to those with complete suppression (n = 5) (516 vs 1456 fmol/punch). [ABSTRACT FROM AUTHOR]

Breast cancer (BC) is among the most commonly diagnosed cancers. Besides mammography, breast ultrasonography and the routinely monitored protein markers, the variations of small molecular metabolites in blood may be of great diagnostic value. This study aimed to quantify specific metabolite markers with potential application in BC detection. The study enrolled 50 participants, 25 BC patients and 25 healthy controls (CTRL). Dried blood spots (DBS) were utilized as biological media and were quantified via a simplified liquid chromatography tandem mass spectrometry (LC-MS/MS) method, used in expanded newborn screening. The targeted metabolomic analysis included 12 amino acids and 32 acylcarnitines. Statistical analysis revealed a significant variation of metabolic profiles between BC patients and CTRL. Among the 44 metabolites, 18 acylcarnitines and 10 amino acids remained significant after Bonferroni correction, showing increase or decrease and enabled classification of BC patients and CTRL. The well-established LC-MS/MS protocol could provide results within few minutes. Therefore, the combination of an easy-to-handle material-DBS and LC-MS/MS protocol could facilitate BC screening/diagnosis and in the next step applied to other cancer patients, as well. [ABSTRACT FROM AUTHOR]

Background Detecting total cholesterol in dried blood spots could aid in identifying individuals with a high likelihood of familial hypercholesterolemia and could be used as a screening measure. This study aims to assess the diagnostic accuracy of dried blood spots on Whatman 903 paper cards using a manual enzymatic technique. Methods: A total of 394 samples were collected as serum and dried blood spots were compared. Cholesterol was determined in serum using the automated reference method, while cholesterol on paper was measured using a manual enzymatic method. Within- and between-day diagnostic variability were analyzed. The correlation between both methods was assessed using Passing–Bablok regression and Bland–Altman plot. Internal validation of our correlation formula was performed on 149 samples, along with external validation of the formula proposed by Corso et al. Results: The within- and between-day coefficient of variation was found to be lower than 10.14% and 14.09%, respectively. Passing–Bablok regression indicated a precision of 0.803 and an accuracy of 0.96. Internal validation precision was measured at 0.716. The resulting positive and negative predicted values were 0.77 and 0.92, respectively, vs. 0.46 and 0.96 from the external formula. Conclusions: Total cholesterol analysis in dried blood spots demonstrates high precision and reproducibility. This method reliably enables the incorporation of this biological marker into neonatal screening for familial hypercholesterolemia detection. [ABSTRACT FROM AUTHOR]

Phosphatidylethanol (PEth) has recently become a popular direct alcohol marker for evaluating drinking behavior. This study aimed at gaining further information on the long‐term stability of five PEth homologues (16:0/18:1, 16:0/18:2, 16:0/20:4, 18:0/18:1, 18:0/18:2) in whole blood (WB) and dried blood spots (DBS) stored at −80°C, 4°C, and room temperature (18°C) over a period of 60 days. Venous blood was taken from 10 volunteers (five females and five males, aged 21–40 years) with a moderate drinking behavior and a negative breath alcohol test at the time of collection. 100 μL aliquots of WB were prepared in addition to 20 μL DBS samples. The initial PEth concentrations were determined on the day of the blood collection. On days 1, 3, 5, 7, 11, 17, 40, and 60, DBS were analyzed in triplicate by means of LC–MS/MS. On these days, WB aliquots having been stored until that time were used to create further DBS in triplicate, which were subsequently stored at 18°C and analyzed in a single batch after day 60. All homologues, except PEth 16:0/20:4, were stable at −80°C in DBS and WB for 60 days. The initial PEth 16:0/18:1 concentrations remained stable in both DBS and WB in all but one volunteer's specimen at 4 and 18°C. Apart from this exception, simultaneously detected PEth homologues 16:0/18:2, 18:0/18:1, and 18:0/18:2 remained stable over at least 40 days in DBS. Nevertheless, the storage time between sample collection and analysis should be kept as short as possible if an ethanol‐free sample cannot be ensured. [ABSTRACT FROM AUTHOR]

Background: Although behavioral interventions show some promise for reducing stimulant use and achieving durable viral suppression in sexual minority men (SMM) with HIV, scalable mHealth applications are needed to optimize their reach and cost-effectiveness. Methods: Supporting Treatment Adherence for Resilience and Thriving (START) is a randomized controlled trial (RCT) testing the efficacy and cost-effectiveness of a mHealth application that integrates evidence-based positive affect regulation skills with self-monitoring of adherence and mood. The primary outcome is detectable HIV viral load (i.e., > 300 copies/mL) from self-collected dried blood spot (DBS) specimens at 6 months. Secondary outcomes include detectable DBS viral load at 12 months, self-reported stimulant use severity, anti-retroviral therapy (ART) adherence, and positive affect over 12 months. A national sample of up to 250 SMM with HIV who screen positive for stimulant use disorder and reporting suboptimal ART adherence is being recruited via social networking applications through April of 2024. After providing informed consent, participants complete a run-in period (i.e., waiting period) including two baseline assessments with self-report measures and a self-collected DBS sample. Those who complete the run-in period are randomized to either the START mHealth application or access to a website with referrals to HIV care and substance use disorder treatment resources. Participants provide DBS samples at baseline, 6, and 12 months to measure HIV viral load as well as complete self-report measures for secondary outcomes at quarterly follow-up assessments over 12 months. Discussion: To date, we have paid $117,500 to advertise START on social networking applications and reached 1,970 eligible participants ($59.77 per eligible participant). Although we identified this large national sample of potentially eligible SMM with HIV who screen positive for a stimulant use disorder and report suboptimal ART adherence, only one-in-four have enrolled in the RCT. The run-in period has proven to be crucial for maintaining scientific rigor and reproducibility of this RCT, such that only half of consented participants complete the required study enrollment activities and attended a randomization visit. Taken together, findings will guide adequate resource allocation to achieve randomization targets in future mHealth research SMM with HIV who use stimulants. Trial Registration: This protocol was registered on clinicaltrials.gov (NCT05140876) on December 2, 2021. [ABSTRACT FROM AUTHOR]

17α-Hydroxyprogesterone (17α-OHP) quantification in dried blood spots (DBS) is essential for newborn screening for congenital adrenal hyperplasia (CAH), which is challenging due to its low physiological concentration. The high false-positive rates of immunoassays necessitate the development of more accurate methods. Liquid chromatography tandem mass spectrometry (LC-MS/MS) offers increased specificity and sensitivity, yet standardized procedures for 17α-OHP measurement are required for clinical application. A candidate reference measurement procedure (cRMP) using isotope dilution LC-MS/MS was developed for 17α-OHP quantification in DBS. By utilizing stable isotope-labeled D8-17α-OHP as an internal standard, the cRMP was optimized, covering sample preparation, calibration, and LC-MS/MS analysis. The method performance was validated across several parameters, including precision, accuracy, specificity, detection limits, and matrix effects. Clinical applicability was further assessed through the establishment of reference intervals for healthy newborns. The developed cRMP exhibited a linear range of 1.00 to 80.00 ng/mL for 17α-OHP, with detection and quantification limits of 0.14 ng/mL and 0.52 ng/mL, respectively. Inter- and intraday precision demonstrated coefficients of variation within 1.27 to 5.69%. The recovery rates and matrix effects were well within acceptable limits, ensuring method reliability. Clinical application showed distinct reference intervals for healthy newborns that were unaffected by sex but influenced by weight and gestational age. This method significantly enhances CAH diagnostic accuracy in newborns, providing a valuable tool for clinical laboratories and improving newborn screening program standardization and traceability. [ABSTRACT FROM AUTHOR]

Objectives: Helicobacter pylori (H. pylori)—a gastric bacteria affecting almost 50% of the global population and leading to ulcers and cancer in severe cases—is a growing health concern among Indigenous populations who report a high burden of reported poor general health and gastrointestinal distress. We test hypothesized associations between H. pylori exposure patterns and environmental, social, and biological conditions among a sample of 212 Indigenous Awajún adults (112 males, 100 females, ages 18–65 years) living in the northern Peruvian Amazon. Materials and Methods: Dried blood spots were analyzed for H. pylori‐specific IgG using a recently developed enzyme‐linked immunosorbent assay. Resulting seropositivity rates and antibody concentrations, proxying past exposures to H. pylori were analyzed in relation to relevant environmental (toilet type, floor material, reported water quality), social (household size and education level), and biological (age, sex, BMI, blood pressure, immune and metabolic biomarkers) factors using multivariable regression analyses. Results: We found near ubiquitous seropositivity for H. pylori exposure in our sample (99.1% seropositive). In the regression analyses, elevations in H. pylori antibody concentrations were significantly higher among males compared to females (β = 0.36, p = 0.01). No associations were found with any other factors. Discussion: Anthropological research in the study communities suggests that the male bias in elevations of H. pylori antibody concentrations is related to cultural and biological factors. Future research is needed to further unravel these biocultural dynamics and determine whether elevations in H. pylori antibody concentrations have clinical relevance for gastrointestinal health outcomes in this population. [ABSTRACT FROM AUTHOR]

A procedure for the simultaneous determination of nine uremic toxins and choline in blood serum is presented. Target substances are selected based on the published data as promising biomarkers for establishing the severity and nature of the progression of immunoglobulin A nephropathy, a kidney disease leading to disability, and in the absence of timely treatment, to the death of young and middle-aged people. Using ultrafiltration, separate determination of free and protein-bound indole uremic toxins was achieved. The use of high-performance liquid chromatography in combination with high-resolution tandem mass spectrometry provides satisfactory analytical accuracy in the absence of the complete chromatographic separation of analytes under standard reversed-phase HPLC conditions. In calibration a solution of albumin in a phosphate buffer solution was used as a surrogate blood serum. Protein concentration of 45 mg/mL and pH 7.4 correspond to these characteristics of native blood serum. The pilot experiment showed the promise of determining the most important indicators of the state of the intestinal microbiome—choline and trimethylamine oxide in dried blood spots. [ABSTRACT FROM AUTHOR]

• Remote dried blood spot (DBS) self-collection in older adults is highly feasible. • Remote DBS yields high-quality spots, sufficient for assaying multiple biomarkers, with high participant adherence. • Inflammatory markers (CRP, IL-6, TNF-α) from self-collected DBS are reliable and valid. Dried blood spots (DBS) provide a minimally invasive method to assess inflammatory markers and can be collected remotely at-home or in-person in the lab. However, there is a lack of methodological information comparing these different collection methods and in older adults. We investigated the feasibility (including adherence, yield, quality, and participant preferences) and measurement properties (reliability, validity) of remotely collected DBS inflammatory markers in older adults. Participants (N = 167, mean age = 72, range: 60–96 years) collected their own DBS (finger prick on filter paper) during three remote interviews over ∼ 6 months. Within 4–5 days on average of their last remote interview, a subset of 41 participants also attended an in-person lab visit that included a researcher-collected DBS sample, venous blood draw, and survey to assess participant preferences of DBS collection. DBS and venous blood were assayed for CRP, IL-6, and TNF-α. Adherence: 98% of expected DBS samples (493 out of 501) were completed and mailed back to the lab. Yield: 97% of DBS samples were sufficient for all assays. Quality: On average, 0.80 fewer optimal spots (60uL of blood that filled the entire circle) were obtained remotely vs. in-person (p = 0.013), but the number of useable or better spots (at least 30-40uL of blood) did not differ (p = 0.89). Preference: A slight majority of participants (54%) preferred in-person DBS collection. Reliability: DBS test–retest reliabilities were good: CRP (ICC = 0.74), IL-6 (ICC = 0.76), and TNF-α (ICC = 0.70). Validity: Inflammatory levels from DBS correlated strongly with levels from venous blood (r = 0.60-0.99) and correlated as expected with sociodemographic and physical health and function variables. Older adults can remotely collect their own DBS to acquire reliable and valid inflammatory data. Remote DBS collection is highly feasible and may allow for inflammatory markers to be assessed in larger, more representative samples than are possible with lab- or clinic-based research designs. [ABSTRACT FROM AUTHOR]

Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic (PK) investigations in situations where venous blood sampling is logistically and/or ethically challenging. The aim of this study was to establish, validate and demonstrate the application of a DBS amoxicillin assay for PK studies in vulnerable populations. The matrix effect, process efficiency (84–104%) and recovery (85–110%) of the liquid chromatography–mass spectrometry (LC–MS/MS) assay for amoxicillin in DBS was determined at 1, 10 and 100 µg/mL, and three different haematocrits. Thermal stability studies of amoxicillin in DBS were performed and a bridging study comprising 26 paired plasma and DBS samples was conducted in four healthy individuals. The limits of detection and quantification were 0.02 and 0.05 µg/mL for plasma and DBS amoxicillin assays, respectively. Accuracy and interday precision of amoxicillin in DBS (0.1–100 µg/mL) were 88–103% and 4.5–9.2%, respectively. At room temperature (22 °C) and 4 °C, amoxicillin was stable in DBS for ≈4 and 26 h, respectively. There was no degradation of amoxicillin in DBS at −20 °C for > 6 months. When comparing DBS and plasma collected from healthy volunteers, the slope of the Deming regression was 0.74. Amoxicillin CL/F estimates from DBS and plasma concentration data were 40.8 and 30.7 L/h/70 kg, respectively; V/F was 43.2 and 37.4 L/70 kg, respectively. In conclusion, amoxicillin can be reliably assayed from DBS in research studies but may have limited application in therapeutic drug monitoring. Due to poor stability at room temperature, amoxicillin DBS samples should be promptly dried and placed in frozen storage. [ABSTRACT FROM AUTHOR]

ABSTRACT Dried blood spots (DBS) are broadly used for different serological analyses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody assessment. In order to biobank DBS samples, an understanding of the preservation of SARS-CoV-2 antibodies is needed. Therefore, we assessed the stability of SARS-CoV-2 antibodies on DBS during short- and long-term storage under different storage temperatures. Seven sample donors were enrolled, each donating twenty 6 mm DBS to assess anti-spike (S1) SARS-CoV-2 IgG antibodies (EUROIMMUN). Baseline samples were analyzed on the day of collection. The remainder of the samples was stored in grip seal bags kept in a cryobox at room temperature/4°C until 2 months after collection and at −20°C until 2 years after collection. Samples were analyzed at regular intervals within the total storage duration and after one and five freeze–thaw cycles. A pooled coefficient of variation was calculated for each storage temperature. We found that anti-S1 SARS-CoV-2 antibodies collected on DBS saver cards remain stable during short-term storage at RT, 4°C, and −20°C (at least to 2 months) and long-term storage at −20°C (at least 2 years). Moreover, up to five freeze–thaw cycles can occur without impacting the anti-S1 SARS-CoV-2 antibody level. The inter-assay coefficient of variation lies between 10 and 15%. As DBS can be preserved for both shorter periods of time at RT and longer periods of time at −20°C, they are a perfect application for studies that require sample shipment by mail, self-sampling studies, studies in limited resource settings and biobanking.IMPORTANCEDried blood spots (DBS) are currently widely used as a microsampling technique for different qualitative and quantitative serological assessments. Yet, there is a lack of long-term stability and storage condition studies. In our study, first, we assessed the stability of SARS-CoV-2 antibodies on DBS up to 2 years post-collection. We believe that our data are not only important for future COVID-19 research but also for studies on other infections/diseases using DBS-based serology.

Remifentanil is an ultra-short-acting synthetic opioid-class analgesic which might be increasingly used “off-label” as pain management during labour. Side effects in parturients during labour, and in the infant at birth are of particular concern, especially respiratory depression which is concentration-dependent, and can occur at levels as low as 3–5 ng mL–1. The safety of such use, particularly in newborns due to remifentanil placental transfer, has not been fully demonstrated yet, partly due to the lack of a suitable non-invasive analytical method. The aim of our work was to develop a sensitive method to monitor the levels of remifentanil in neonates by a non-invasive sampling of umbi lical cord blood to support efficacy and safety trials. The presented LC-MS method is sensitive enough to reliably quantify remifentanil in just 20 µL of blood at only 0.3 ng mL–1. The dried blood spot sample preparation included solvent extraction with subsequent solid-phase extraction. The method was validated in terms of accuracy, precision, recovery, matrix effect, and stability, and was successfully applied to a small pilot study. The estimated arterial blood concentrations at the time of delivery ranged from 0.2 to 0.3, and up to 0.9 ng mL–1 in neonatal, and maternal samples, respectively.

Introduction: Screening for chronic kidney disease relies on accurate and precise creatinine measurements. Traditionally, creatinine is measured in serum or plasma using high-throughput chemistry analyzers. However, dried blood spots (DBS) can also be utilized to improve testing access. Methods: Samples were obtained from a 6 mm DBS punch, which was reconstituted in water before undergoing an acetonitrile crash. The resulting supernatant was diluted using an 80:20 acetonitrile: water before injection. Creatinine was identified using an isocratic gradient, and detected using an API 4000 triple quadrupole mass analyzer. Quantification relied on matrix-matched calibrators, with values harmonized to the Roche Cobas enzymatic assay. Validation studies assessing method performance included precision, linearity, accuracy, method comparison, stability, interference, and matrix effects. Results: The LC-MSMS assay was linear from 0.3 to 20 mg/dL (y = 1.02x-0.11; R2 = 0.996). Precision ranged from 5.2 to 8.1 % using matrix-matched controls (n = 4) that spanned the analytical measurement range. LC-MSMS results corresponded to the enzymatic assay (Roche) with a fitted line equation of y = 0.956x–0.07 (R2 = 0.995; n = 173). The Siemens and Roche enzymatic assays demonstrated higher accuracy in correlating to the DBS creatinine concentration (n = 40 paired venous/DBS collections) compared to the Beckman Jaffe assay (-2.5 % and −0.8 % versus −6.3 % and −4.1 %, respectively) or the iSTAT (-28.4 % and −27.1 %, respectively). Accuracy was unaffected by hematocrit, blood spot volume, excess IgG or IgA, or hypertriglyceridemia. No matrix effects were observed, and both extraction and processing efficiency were robust.Ambient stability extended to at least 10 days, and exposure to extreme temperature did not affect the creatinine results. Conclusion: We successfully developed an accurate and precise LC-MSMS method for quantifying creatinine in DBS.

BackgroundPreterm birth is a leading cause of death in children under the age of five. The risk of preterm birth is increased by maternal HIV infection as well as by certain antiretroviral regimens, leading to a disproportionate burden on low- and medium-income settings where HIV is most prevalent. Despite decades of research, the mechanisms underlying spontaneous preterm birth, particularly in resource limited areas with high HIV infection rates, are still poorly understood and accurate prediction and therapeutic intervention remain elusive.ObjectivesMetabolomics was utilized to identify profiles of preterm birth among pregnant women living with HIV on two different antiretroviral therapy (ART) regimens.MethodsThis pilot study comprised 100 mother-infant dyads prior to antiretroviral initiation, on zidovudine monotherapy or on protease inhibitor-based antiretroviral therapy. Pregnancies that resulted in preterm births were matched 1:1 with controls by gestational age at time of sample collection. Maternal plasma and blood spots at 23-35 weeks gestation and infant dried blood spots at birth, were assayed using an untargeted metabolomics method. Linear regression and random forests classification models were used to identify shared and treatment-specific markers of preterm birth.ResultsClassification models for preterm birth achieved accuracies of 95.5%, 95.7%, and 80.7% in the untreated, zidovudine monotherapy, and protease inhibitor-based treatment groups, respectively. Urate, methionine sulfone, cortisone, and 17α-hydroxypregnanolone glucuronide were identified as shared markers of preterm birth. Other compounds including hippurate and N-acetyl-1-methylhistidine were found to be significantly altered in a treatment-specific context.ConclusionThis study identified previously known as well as novel metabolomic features of preterm birth in pregnant women living with HIV. Validation of these models in a larger, independent cohort is necessary to ascertain whether they can be utilized to predict preterm birth during a stage of gestation that allows for therapeutic intervention or more effective resource allocation.

Stored dried blood spots (DBSs) give significant specimens for retrospective detection of inborn errors of metabolisms (IEM) including for validation studies through newborn screening (NBS) programs. Inborn errors of metabolisms have severe medical outcomes in infants and newborns, and initial identification and errors of metabolism treatment can lessen morbidity and mortality. The study investigated the impacts of different conditions for storage (humidity and temperature) experienced throughout the stored dried blood specimen gathering and transportation of the metabolites tested in the NBS program. Stored dried blood spots collected from healthy newborns and kept at room temperatures (RT, 22–25 °C), 37 °C, and 4 °C were examined for acylcarnitine and amino acid panels for 5 days, 1 month, and 2 months using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The outcomes display the decay patterns of amino acids and acylcarnitines at different temperatures and elevated humidity. The study findings indicate that humidity and temperature during sample transit affect the integrity of stored dried blood within a short period. The packaging of blood spots should be done correctly and sent to a newborn screening laboratory immediately. Including a maintained stored dried blood kept along with earlier specimens utilized in retrospective diagnostic cohort studies would give insights into the sample's condition. [ABSTRACT FROM AUTHOR]

Certain micronutrients exhibit immunomodulatory effects. However, no intervention has yet investigated the effect of individualized supplementation on the severity of upper respiratory tract infections (URIs). Therefore, we investigated whether a personalized supplementation moderates the incidence and severity of URI. Selenium, zinc, and vitamin D were measured in dried blood spots from 59 healthy participants. Accordingly, a personalized supplement was provided with or without the respective micronutrients. We used WURSS-21 questionnaires to assess the disease status. The blood values converged during the intervention and micronutrients no longer differed between treated and untreated volunteers at the end of the intervention period. The incidence and severity of the illness did not significantly differ between the groups. However, when analyzing the WURSS-21 scores by the intention to treat, the initially randomized treatment arm revealed a significantly higher score than the placebo arm. Upon acute administration, individualized combinations of selenium, zinc and vitamin D do not reduce the number, or contribute to a milder course of URIs. Therefore, supplementation in acute infectious situations seems questionable. Further studies must address the habitual diet in more detail, to better understand the impact of individual micronutrient status on the prevention of URI. [ABSTRACT FROM AUTHOR]

Determination of proteins from dried matrix spots using MS is an expanding research area. Mainly, the collected dried matrix sample is whole blood from a finger or heal prick, resulting in dried blood spots. However as other matrices such as plasma, serum, urine, and tear fluid also can be collected in this way, the term dried matrix spot is used as an overarching term. In this review, the focus is on advancements in the field made from 2017 up to 2023. In the first part reviews concerning the subject are discussed. After this, advancements made for clinical purposes are highlighted. Both targeted protein analyses, with and without the use of affinity extractions, as well as untargeted, global proteomic approaches are discussed. In the last part, both methodological advancements are being reviewed as well as the possibility to integrate sample preparation steps during the sample handling. The focus, of this so‐called smart sampling, is on the incorporation of cell separation, proteolysis, and antibody‐based affinity capture. [ABSTRACT FROM AUTHOR]

Phosphatidylethanol (PEth) is a direct alcohol biomarker to monitor individuals' drinking behavior that has gained recognition in clinical and forensic settings. The increasing application of the marker makes investigation of the preanalytical handling necessary, and analyte stability deserves major attention. This study was conducted to investigate the change of six PEth homologues' concentration, stored in authentic samples of EDTA blood over a course of 30 days at room temperature (n = 62). The stability criterion of concentration being ±15% of the original concentration was fulfilled at mean for 10, 3, 2, 5, 2, and 7 days for PEth 16:0/18:1, 16:0/18:2, 16:0/20:4, 18:0/18:1, 18:0/18:2, and 18:1/18:1, respectively. Regarding all homologues, there were samples in which concentration had declined by >15% or by more than the critical difference on day 1. Overall, calculated concentration declines were very inhomogeneous, with inter‐sample differences of 43%–73% after 30 days. PEth 16:0/18:2, 16:0/20:4, and 18:0/18:2 declined to a greater extent than PEth 16:0/18:1. Blood alcohol concentration was measured >0.1‰ in 25 samples. Three of the six samples that exceeded 115% of initial concentrations were positive for blood alcohol. The study results add to the previously reported information on PEth stability and firstly look at six homologues in comparison. Due to the high scatter of stability among the samples and the observed poor stabilities in some, it can be concluded that transportation and storage times, especially if cooling cannot be provided, must be kept short. If analyzing from dried blood, spotting should preferably be conducted at the site of sampling. [ABSTRACT FROM AUTHOR]

Background: Amino acid analysis is an important tool for the diagnosis of metabolic disorders in newborns. Today, Liquid Chromatography tandem mass spectrometry (LC-MS/MS) has emerged as a powerful technique for amino acid analysis. We aimed to determine the local normal range of amino acids in dried blood spot (DBS) samples of neonates using LC-MS/MS. Methods: A total of 1005 samples from healthy neonates of northeast and east of Iran aged 2-7 days were utilized for normal range determination. The amino acids were extracted from dried blood spot samples using organic solvent and then analyzed using LC-MS/MS system. The 1%, 2.5%, 97.5%, and 99% percentiles were calculated, and the results were compared to the global cut-off values. Results: The results showed that glutamic acid has the highest concentration range among amino acids evaluated in this study (178.94 - 421.31μmol/L). Moreover, the plasma concentrations of Glycine (142.65 - 397.06 μmol/L), Alanine (97.00-349.72 μmol/L), Proline (63.77 - 236.53 μmol/L), and Tyrosine (25.79 - 150.58 μmol/L) were in the next ranks. Comparing the obtained results with the global values obtained in the R4S study indicated a slight difference between the obtained local normal values and the global values. Conclusion: The calculated values were slightly different from global values obtained in the R4S study and regional values calculated in other studies. This further emphasized the importance of the local establishment of reference values, which facilitates the correct interpretation and diagnosis in the Newborn Screening Programs. [ABSTRACT FROM AUTHOR]

BACKGROUND: We aimed to evaluate the precision of Alzheimer's disease (AD) and neurodegeneration biomarker measurements from venous dried plasma spots (DPSvenous) for the diagnosis and monitoring of neurodegenerative diseases in remote settings. METHODS: In a discovery (n = 154) and a validation cohort (n = 115), glial fibrillary acidic protein (GFAP); neurofilament light (NfL); amyloid beta (Aβ) 40, Aβ42; and phosphorylated tau (p‐tau181 and p‐tau217) were measured in paired DPSvenous and ethylenediaminetetraacetic acid plasma samples with single‐molecule array. In the validation cohort, a subset of participants (n = 99) had cerebrospinal fluid (CSF) biomarkers. RESULTS: All DPSvenous and plasma analytes correlated significantly, except for Aβ42. In the validation cohort, DPSvenous GFAP, NfL, p‐tau181, and p‐tau217 differed between CSF Aβ‐positive and ‐negative individuals and were associated with worsening cognition. DISCUSSION: Our data suggest that measuring blood biomarkers related to AD pathology and neurodegeneration from DPSvenous extends the utility of blood‐based biomarkers to remote settings with simplified sampling conditions, storage, and logistics. Highlights: A wide array of biomarkers related to Alzheimer's disease (AD) and neurodegeneration were detectable in dried plasma spots (DPSvenous).DPSvenous biomarkers correlated with standard procedures and cognitive status.DPSvenous biomarkers had a good diagnostic accuracy discriminating amyloid status.Our findings show the potential interchangeability of DPSvenous and plasma sampling.DPSvenous may facilitate remote and temperature‐independent sampling for AD biomarker measurement.Innovative tools for blood biomarker sampling may help recognizing the earliest changes of AD. [ABSTRACT FROM AUTHOR]

The aim of this study was to monitor seven phosphatidylethanol (PEth) homologues in dried blood spots (DBS) and ethyl glucuronide in hair (EtGH) over a 6‐month period of drinking while documenting the daily drinks (amount and type) of alcohol via app. A total of 23 volunteers (12 males and 11 females) aged 19–54 years were enrolled. At four‐weekly intervals, capillary blood to create DBS and after 3 and 6 months, respectively, a strand of hair (proximal, 3 cm) was collected. Analyses of EtGH and PEth homologues were performed using liquid chromatography–tandem mass spectrometry. All participants consumed alcohol during the 6 months. Only one participant tested negative for both PEth and EtGH. Eight participants had PEth 16:0/18:1 concentrations between 20 and <210 ng/mL (mean: 45.6 ng/mL) but EtGH concentrations below 5 pg/mg. PEth 16:0/18:1 concentrations between 20 and <210 ng/mL and EtGH concentrations between 5 and <30 pg/mg were assigned to eight subjects, uniformly matching them in the category of socially accepted drinking behavior. Four test subjects exceeded the cutoff for social drinking behavior in both PEth 16:0/18:1 (mean: 528 ng/mL) and EtGH (mean: 84.5 pg/mg). Two participants exceeded the threshold for PEth 16:0/18:1 of 210 ng/mL in blood but remained below 30 pg EtG/mg hair. PEth showed a higher detection rate for alcohol consumption than EtGH did. Moreover, PEth concentrations reacted quickly to changes in drinking behavior, whereas EtGH concentrations remained similar over time. [ABSTRACT FROM AUTHOR]

Background: In Equatorial Guinea, only 54 % of people living with HIV know their HIV status. There are no confirmatory or molecular diagnostic techniques for early diagnosis or monitoring of infection in the country. Rapid diagnostic tests can induce false-positive diagnoses if used as a confirmatory technique. Our study aimed to identify the challenges of early HIV diagnosis in Equatorial Guinea by analyzing the rate of false positive diagnoses, diagnostic and therapeutic delays, and treatment failures among those on antiretroviral therapy. Methods: From 2019–2022, dried blood from 341 children, adolescents and adults diagnosed in Equatorial Guinea as HIV-positive by rapid diagnostic testing, and from 54 HIV-exposed infants were collected in Bata and sent to Madrid to confirm HIV-infection by molecular (Xpert HIV-1Qual, Cepheid) and/or serological confirmatory assays (Geenius-HIV-1/2, BioRad). HIV diagnostic delay (CD4 1,000RNA-HIV-1-copies/ml) were also studied after viral quantification (XpertVL HIV-1, Cepheid). Results: False-positive diagnoses were identified in 5 % of analysed samples. HIV infection was confirmed in 90.5 % of previously diagnosed patients in Equatorial Guinea and 3.7 % of HIV-exposed children undiagnosed in the field. Two-thirds of each new HIV patient had delayed diagnosis, and one-third had advanced disease. Treatment delay occurred in 28.3 % of patients, being around four times more likely in adolescents/adults than children. More than half (56 %) of 232 treated patients presented treatment failure, being significantly higher in children/adolescents than in adults (82.9 %/90 % vs. 45.6 %, p

Background: Malaria is a parasitic disease that affects many of the poorest economies, resulting in approximately 241 million clinical episodes and 627,000 deaths annually. Piperaquine, when administered with dihydroartemisinin, is an effective drug against the disease. Drug concentration measurements taken on day 7 after treatment initiation have been shown to be a good predictor of therapeutic success with piperaquine. A simple capillary blood collection technique, where blood is dried onto filter paper, is especially suitable for drug studies in remote areas or resource-limited settings or when taking samples from children, toddlers, and infants. Methods: Three 3.2 mm discs were punched out from a dried blood spot (DBS) and then extracted in a 96-well plate using solid phase extraction on a fully automated liquid handling system. The analysis was performed using LC-MS/MS with a calibration range of 3 – 1000 ng/mL. Results: The recovery rate was approximately 54–72 %, and the relative standard deviation was below 9 % for low, middle and high quality control levels. The LC-MS/MS quantification limit of 3 ng/mL is sensitive enough to detect piperaquine for up to 4–8 weeks after drug administration, which is crucial when evaluating recrudescence and drug resistance development. While different hematocrit levels can affect DBS drug measurements, the effect was minimal for piperaquine. Conclusion: A sensitive LC-MS/MS method, in combination with fully automated extraction in a 96-well plate format, was developed and validated for the quantification of piperaquine in DBS. The assay was implemented in a bioanalytical laboratory for processing large-scale clinical trial samples.

Dried blood spots (DBSs) are formed by collecting a small sample of blood on specialized filter paper and allowing it to dry naturally. Various domains of life sciences and drug research extensively use DBSs as a sampling technique. The “Hematocrit (Ht) effect” affects assay bias, and several strategies have been put forth to deal with it, including the correction of quantified concentrations using an appropriate correction factor. The approach was previously applied, following the utilization of an image processing algorithm developed in Matlab® to derive a reliable equation correlating DBS areas to Ht% values. The present work looks more closely at the application of image analysis to the evaluation of Ht in DBS samples. Utilizing image analysis software, DBS samples with known Ht values were processed. Preparation of cards has followed a previously developed protocol for the appropriate formation of uniform area DBSs, irrespective of Ht. The resulting areas showed close resemblance to the respective theoretical areas calculated by applying the correlation equation. Following that, the equation was utilized to determine the Ht values for each sample, and a comprehensive comparison of measured versus calculated Ht was carried out using various statistical approaches for method comparison. The results demonstrated a strong correlation, suggesting the method’s viability in estimating Ht for unknown DBS samples.

Hepatitis B remains a public health problem worldwide despite vaccine availability. Although the existing diagnostic tools help detect the infection, logistics support and limited resources and technologies affect their usefulness and reliability in developing countries. This systematic review evaluated the performance of dried blood spots (DBS) as a collection and storage tool for diagnosing an hepatitis B virus (HBV) infection. A comprehensive search using OVID, Scopus and CINAHL databases was performed to collate articles published up to April 2023 that detected Hepatitis B infections using DBS. Five reviewers independently performed identification, screening, quality assessment and data extraction. A qualitative synthesis of the included studies was conducted. Of the 402 articles, 78 met the inclusion criteria. The results show that most studies focused on populations with known HBV, HCV and/or HIV status. Approximately half (49%) of the included studies utilized the Whatman Protein Saver Card for DBS collection. The DBS samples were then predominantly stored in room temperature conditions. In line with this, storage conditions influenced the concentration and stability of the analyte from the DBS samples, affecting the accuracy of downstream diagnostic methods. ELISA methods, using hepatitis B surface antigen (HBsAg) as an HBV marker, were the most widely used diagnostic tool for detecting HBV infection in DBS samples. The simplicity and cost‐effectiveness of the ELISA technique highlight its potential to be used in low‐resource settings. In line with this, the detection of HBsAg using an ELISA immunoassay had higher sensitivity (85.6%–100%), and specificity (95%–100%) ranges as compared to other target molecules and methods. Although this review only performed a qualitative analysis, DBS offers a promising method for collecting and storing blood samples; however, the standardization of sampling, storing conditions and diagnostic techniques is required to ensure sustainable application. [ABSTRACT FROM AUTHOR]

In order to identify changes in the blood proteome of healthy volunteers after passive tilt test carried out on day 19 of head-down bed rest, a chromato-mass-spectrometric analysis of samples of dried blood spots was carried out. It was revealed that the body's response to the tilt test was characterized by a decrease in the level of HDL and kininogen-1. After the tilt test, we observed an increase in the level of vimentin, vitamin K-dependent protein C, Wnt signaling pathway proteins, proteins involved in autophagy and adaptive immune response, focal adhesion proteins, vascular damage marker S100A8, PEDF regulator, and some proteins of the heart: cardiac actin ACTC1 and transcription factor GATA4. The obtained results lay the foundation for future research in the framework of identifying the risks of developing cardiovascular changes in astronauts after space flights. [ABSTRACT FROM AUTHOR]

Introduction: The exclusion of affected populations from Alzheimer's disease (AD) clinical research limits our understanding of disease heterogeneity and its impact on clinical care. While micro sampling with dried plasma spots (DPS) can promote inclusivity by enabling sample collection in remote areas, current techniques lack the sensitivity required for the quantification of phosphorylated tau at Thr181 (pTau‐181) in DPS extracts. Methods: We developed an assay for pTau‐181 with reduced bead count and improved bead read efficiency (BRE) using a prototype Simoa instrument. This novel assay's performance was evaluated against standard pTau‐181 assays on two Simoa platforms, and DPS extracts were tested for pTau‐181 quantification feasibility. Results: The novel assay quantifies pTau‐181 at concentrations up to 16x lower than traditional pTau‐181 assays on HD‐X and SR‐X platforms. DPS extracts tested with our low‐bead assay were quantified considerably above the lower limit of quantification (LLOQ), indicating the suitability of this assay for future DPS extract measurements. Discussion: Implementing DPS sampling and pTau‐181 quantification could increase participation from underrepresented groups in AD research. However, additional assay optimization and an in‐depth study of preanalytical sample stability are essential for the transition to clinical applicability. [ABSTRACT FROM AUTHOR]

INTRODUCTION: The apolipoprotein E (APOE) ε4 allele is associated with high risk for Alzheimer's disease. It is unclear whether individual levels of the circulating apoE4 protein in ε4 carriers confer additional risk. Measuring apoE4 protein levels from dried blood spots (DBS) has the potential to provide information on genetic status as well as circulating levels and to include these measures in large survey settings. METHODS: We developed a multiplex immunoassay to detect apoE4 protein levels in DBS from 15,974 participants, aged 50+ from Wave 6 of the Survey of Health, Ageing and Retirement in Europe (SHARE). RESULTS: The apoE4 protein signal was presented in two separable distributions. One distribution corresponded to carriers of at least one copy of the ε4 allele. Fieldwork cofounders affected protein levels but did not explain individual differences. DISCUSSION: Future research should investigate how genotype and apoE4 level interact with lifestyle and other variables to impact cognitive aging. [ABSTRACT FROM AUTHOR]

Despite being a minimally invasive sample source, dried blood spots (DBS) generally pose the challenge of efficient sample extraction for broad metabolomics applications. This is particularly true for the quantification of steroids using non-derivatized liquid chromatography tandem mass spectrometry assays. To address these limitations, we have demonstrated the use of electric field as a driver for sample preparation from DBS samples to simultaneously quantify testosterone (T), 17α-hydroxyprogesterone (17-OHP), progesterone (P), and cortisol (C), using both standard electroporation cuvettes, as well as a novel custom vertical electric field setup. Our findings, backed by computational modeling, show that a 10V DC application for 180 s can draw out twice the amount of the aforementioned steroids from both Whatman-903 and DMPK-C sample collection cards using our novel device when compared to standard solvent-based collection methods. This study not only introduces the use of electric field for sample preparation for metabolomics, but additionally introduces a novel device that eliminates the electric double layer effect in the process.

The aim is to evaluate the effect of viral inactivation methods on the quality and quantity of compounds in dried blood spots (DBS).

Abstract Measurement of plasma and dried blood spot (DBS) phenylalanine (Phe) is key to monitoring patients with phenylketonuria (PKU). The relationship between plasma and capillary DBS Phe concentrations has been investigated previously, however, differences in methodology, calibration approach and assumptions about the volume of blood in a DBS sub‐punch has complicated this. Volumetric blood collection devices (VBCDs) provide an opportunity to re‐evaluate this relationship. Paired venous and capillary samples were collected from patients with PKU (n = 51). Capillary blood was collected onto both conventional newborn screening (NBS) cards and VBCDs. Specimens were analysed by liquid‐chromatography tandem mass‐spectrometry (LC–MS/MS) using a common calibrator. Use of VBCDs was evaluated qualitatively by patients. Mean bias between plasma and volumetrically collected capillary DBS Phe was −13%. Mean recovery (SD) of Phe from DBS was 89.4% (4.6). VBCDs confirmed that the volume of blood typically assumed to be present in a 3.2 mm sub‐punch is over‐estimated by 9.7%. Determination of the relationship between plasma and capillary DBS Phe, using a single analytical method, common calibration and VBCDs, demonstrated that once the under‐recovery of Phe from DBS has been taken into account, there is no significant difference in the concentration of Phe in plasma and capillary blood. Conversely, comparison of plasma Phe with capillary DBS Phe collected on a NBS card highlighted the limitations of this approach. Introducing VBCDs for the routine monitoring of patients with PKU would provide a simple, acceptable specimen collection technique that ensures consistent sample quality and produces accurate and precise blood Phe results which are interchangeable with plasma Phe.

The use of dried blood spots (DBS) obtained from the heels of infants has many advantages over the collection of whole blood samples. DNA extracted from DBS can be used to detect genetic diseases by PCR, which has contributed to the development of population-based newborn screening worldwide. Since January 2023, the list of identified diseases includes a group of primary immunodeficiencies (PIDs), associated with the absence or decrease in the levels of T and/or B lymphocytes, determined as part of screening by the levels of TREC and KREC molecules in peripheral blood, respectively. Quantitative analysis requires special attention to biological material. The aim is to evaluate the impact of the preanalytical step on the quantitative analysis of TREC/KREC levels in peripheral blood.The material included 5219 DBS obtained from infants on days 3-4 of life, as well as DBS prepared from the whole blood of 100 apparently healthy individuals aged 18 to 29 years. A comparative analysis of the TREC/KREC molecules number in correctly and incorrectly collected DBS from newborns and adults, as well as depending on the volume of applied blood, was carried out by RT-PCR using test systems to assess the levels of TREC and KREC in peripheral blood. DBS quality was assessed visually.In the first months of the project, a significant number of incorrectly taken samples were identified – over a third of all DNA maps received for each corresponding month. As a result of additional training of medical staff, the amount of incorrectly collected material decreased to a level not exceeding 1% of all monthly samples collected. When using DNA extracted from DBS with application errors, the majority of samples (64% for newborns, 78% for adults) failed to obtain a result. In the remaining cases, the results obtained were significantly lower than the normal levels of TREC/KREC determined in the same samples with correct DBS collection (all p < 0.0001, 95% CI). The volume of blood used when correctly applied to Guthrie cards did not affect the results obtained, TREC and KREC levels were comparable; when comparing the medians calculated for each group of samples, no significant differences were identified (p > 0.05).When quantitatively analyzing TREC/KREC levels in peripheral blood, correctly taken material is fundamental importance to obtain reliable indicators, primarily to exclude false-positive results. To minimize errors in the preanalytical stage, additional training of medical personnel is necessary to control and/or correct errors.

Neonatal screening is a mandatory newborn screening procedure that detects the presence of genetic diseases. Dry blood stains are used for mass screening of children. This technology is the most affordable and convenient for the transportation and storage of biological material. DNA extraction is one of the important steps in molecular diagnostics, the accuracy of which is particularly important in genetic analysis. Different DNA extraction kits offer different protocols and reagents, which may vary in efficiency and quality of extraction.The aim of our work was to perform a comparative analysis of reagent kits for DNA extraction from dried blood spots.The materials were dried blood drop samples on Guthrie cards obtained from healthy preterm infants on day 3-4 of life as part of a newborn screening program.The study methods included spectrophotometric analysis to determine the concentration and purity of DNA, the simplicity of protocols, the duration of isolation, and the possibility of automating the process were also evaluated. The efficiency of DNA isolation using different reagent kits was additionally monitored by real-time PCR results using a test system to assess the level of TREC and KREC in peripheral blood, since quantitative analysis requires more attention to the material under study.In assessing the purity of the nucleic acid extracted using four kits analyzed, successful deproteinization of DNA samples and relative purity could be observed. The average DNA purity for the “Extra-DNA-Bio” set was 2.2±0.23, for “EXTRA-prep PS” – 1.89±0.23, for “MagnoPrime UNI” with manual and automatic isolation – 2.31±0.21 and 2.85±0.09, respectively. The average DNA concentration for the Extra-DNA-Bio kit was 15.28 μg/mL, for the EXTRA-Prep PS kit it was 16.26 μg/mL, and for the MagnoPrime UNI for manual and automated isolation it was 62.5 μg/mL and 102.28 μg/mL, respectively. According to the applied Kraskell-Wallis criterion and Dunn’s test, significant differences in both TREC and KREC parameters are present between the group of DNA samples extracted using the “MagnoPrime UNI” reagent kit for manual extraction and the groups of samples extracted by other methods (“MagnoPrime UNI” for automatic extraction) or “Extra-DNA-Bio” and “EXTRA-Prep PS” kits.In the course of the present study, four comparable reagent sets demonstrated a high level of convergence of the obtained data, satisfying all the necessary parameters for further molecular genetic analysis, can be used for neonatal screening and in other areas of research requiring DNA extraction from a dried blood spots.

Phosphatidylethanol (PEth) is a sensitive and specific biomarker of alcohol consumption in the prior 2-3 weeks. Standard, manual PEth testing using dried blood spots (DBS) is a multi-step time-consuming process. A novel, automated processing and testing method has been developed to decrease DBS processing and testing time. We conducted automated testing, using regioisomerically pure PEth reference material, on randomly selected DBS, which had previously been tested via manual methods and then stored for 3-6 years at -80 °C, to compare the results (PEth 16:0/18:1 homologue). We chose samples for re-testing using categories found in the literature as follows: 1) PEth 200-1000 ng/mL; 4) PEth >1000 ng/mL. We calculated agreement between the categories using the weighted kappa statistic (n = 49 DBS). We quantified agreement between continuous measures using the intraclass correlation coefficient (ICC), and further described the relationship between variables using Spearman correlation. The median PEth result was 155 ng/mL (interquartile range [IQR]: 1-1312 ng/mL) via automated methods and 98.8 ng/mL (IQR: 10.2-625.0 ng/mL) via manual methods. The weighted kappa comparing the automated to manual PEth results was 0.76 [95% Confidence Interval (CI): 0.66-0.86]. The ICC was 0.69 (95% CI: 0.54-0.79), and the Spearman correlation was 0.98 (95% CI: 0.95-0.99). While the new methods yielded somewhat higher PEth values, we found good to excellent agreement between clinically relevant PEth categories. Automated DBS processing and testing using new reference standards are promising methods for PEth testing.

In 2015, U.K. newborn screening (NBS) laboratory guidelines were introduced to standardize dried blood spot (DBS) specimen quality acceptance and specify a minimum acceptable DBS diameter of ≥7 mm. The UK ‘acceptable’ avoidable repeat rate (AVRR) is ≤2%. To assess inter-laboratory variability in specimen acceptance/rejection, two sets of colored scanned images (n = 40/set) of both good and poor-quality DBS specimens were distributed to all 16 U.K. NBS laboratories for evaluation as part of an external quality assurance (EQA) assessment. The mean (range) number of specimens rejected in the first EQA distribution was 7 (1–16) and in the second EQA distribution was 7 (0–16), demonstrating that adherence to the 2015 guidelines was highly variable. A new minimum standard for DBS size of ≥8 mm (to enable a minimum of six sub-punches from two DBS) was discussed. NBS laboratories undertook a prospective audit and demonstrated that using ≥8 mm as the minimum acceptable DBS diameter would increase the AVRR from 2.1% (range 0.55% to 5.5%) to 7.8% (range 0.55% to 22.7%). A significant inverse association between the number of specimens rejected in the DBS EQA distributions and the predicted AVVR (using ≥8 mm minimum standard) was observed (r = −0.734, p = 0.003). Before implementing more stringent standards, the impact of a standard operating procedure (SOP) designed to enable a standardized approach of visual assessment and using the existing ≥7 mm diameter (to enable a minimum of four sub-punches from two DBS) as the minimum standard was assessed in a retrospective audit. Implementation of the SOP and using the ≥7 mm DBS diameter would increase the AVRR from 2.3% (range 0.63% to 5.3%) to 6.5% (range 4.3% to 20.9%). The results demonstrate that there is inconsistency in applying the acceptance/rejection criteria, and that a low AVVR is not an indication of good-quality specimens being received into laboratories. Further work is underway to introduce and maintain standards without increasing the AVRR to unacceptable levels.

Background Detecting total cholesterol in dried blood spots could aid in identifying individuals with a high likelihood of familial hypercholesterolemia and could be used as a screening measure. This study aims to assess the diagnostic accuracy of dried blood spots on Whatman 903 paper cards using a manual enzymatic technique. Methods: A total of 394 samples were collected as serum and dried blood spots were compared. Cholesterol was determined in serum using the automated reference method, while cholesterol on paper was measured using a manual enzymatic method. Within- and between-day diagnostic variability were analyzed. The correlation between both methods was assessed using Passing–Bablok regression and Bland–Altman plot. Internal validation of our correlation formula was performed on 149 samples, along with external validation of the formula proposed by Corso et al. Results: The within- and between-day coefficient of variation was found to be lower than 10.14% and 14.09%, respectively. Passing–Bablok regression indicated a precision of 0.803 and an accuracy of 0.96. Internal validation precision was measured at 0.716. The resulting positive and negative predicted values were 0.77 and 0.92, respectively, vs. 0.46 and 0.96 from the external formula. Conclusions: Total cholesterol analysis in dried blood spots demonstrates high precision and reproducibility. This method reliably enables the incorporation of this biological marker into neonatal screening for familial hypercholesterolemia detection.

Abstract Background Suboptimal antiretroviral (ART) adherence can lead to virologic failure with consequent HIV-1 resistance. Tenofovir diphosphate (TFV-DP) in dried blood spots (DBS) is a powerful biomarker of cumulative adherence, predictive of future viremia. It has been associated with resistance in Persons With HIV (PWH) in South Africa and the US. We explored the relationship of TFV-DP concentrations with antiretroviral drug resistance at the time of treatment failure in SA. Methods Adult PWH from health clinics in Cape Town, South Africa on efavirenz-based first-line ART containing tenofovir disoproxil fumarate (TDF) with an undetectable ( 400 copies/mL triggered HIV-1 genotyping at the subsequent visit. An electronic adherence (EA) device monitored ART adherence in real-time, estimated as a percent for the 30-days prior to VB. Wilcoxon rank sum test was used to compare median [IQR] TFV-DP by genotype outcome. Results Of 250 individuals, (n = 195, 78% women), 21 experienced VB, with a median of 5 [4;7] months on study, and a median EA of 33.3 [13.3;53.3]%. Demographic characteristics between those with and without VB were similar. Median VL at VB was 4.0 [3.2;4.5] log copies/mL. TFV-DP concentrations trended down towards the VB visit. Median TFV-DP concentrations were significantly higher in those HIV-1 genotype did not amplify due to being virally suppressed at the subsequent visit (n = 10; 380 [227–661] fmol/punch, p = 0.035; EA 45 [24.9; 59.2]%); than in those who were successfully genotyped with evidence of drug resistance (n = 5, 241 [150–247] fmol/punch, EA 20 [6.7;36.7]%) and in individuals who did not have resistance (n = 3, 39.9 [16.6; 93.9] fmol/punch; EA 33.3 [16–38]%). Three genotype collections were not done. Only non-nucleoside reverse transcriptase inhibitor-associated mutations were identified on resistance testing. (K103N, E138K, Y118H). Conclusion TFV-DP in DBS showed a step-wise inverse relationship with VB and drug resistance, with evidence of low cumulative ART adherence in PWH who developed antiretroviral resistance. Monitoring TFV-DP concentrations could be a valuable tool for predicting future VB and future resistance.

In Haiti in 2017, the prevalence of serum vibriocidal antibody titers against Vibrio cholerae serogroup O1 among adults was 12.4% in Cerca-la-Source and 9.54% in Mirebalais, suggesting a high recent prevalence of infection. Improved surveillance programs to monitor cholera and guide public health interventions in Haiti are necessary.