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Background The key correlate of protection of respiratory syncytial virus (RSV) vaccines and monoclonal antibodies (mAbs) is virus neutralization, measured via sera obtained through venipuncture. Dried blood obtained with a finger prick can simplify acquisition, processing, storage, and transport in trials and thereby reduce costs. In this study, we validate an assay to measure RSV neutralization in dried capillary blood. Methods Functional antibodies were compared between matched serum and dried blood samples from a phase 1 trial with RSM01, an investigational anti-RSV prefusion F mAb. Hep-2 cells were infected with a serial dilution of sample-virus mixture by using RSV-A2-mKate to determine the half-maximal inhibitory concentration. Stability of dried blood was evaluated over time and during temperature stress. Results Functional antibodies in dried blood were highly correlated with serum (R 2 = 0.98, P <.0001). The precision of the assay for dried blood was similar to serum. The function of mAb remained stable for 9 months at room temperature and frozen dried blood samples. Conclusions We demonstrated the feasibility of measuring RSV neutralization using dried blood as a patient-centered solution that may replace serology testing in trials against RSV or other viruses, such as influenza and SARS-CoV-2. Clinical Trials Registration.  NCT05118386 (ClinicalTrials.gov). [ABSTRACT FROM AUTHOR]

Blood microsampling (BµS) offers an alternative to conventional methods that use plasma or serum for profiling human health, being minimally invasive and cost effective, especially beneficial for vulnerable populations. We present a non‐systematic review that offers a synopsis of the analytical methods, applications and perspectives related to dry blood microsampling in targeted and untargeted metabolomics and lipidomics research in the years 2022 and 2023. BµS shows potential in neonatal and paediatric studies, therapeutic drug monitoring, metabolite screening, biomarker research, sports supervision, clinical disorders studies and forensic toxicology. Notably, dried blood spots and volumetric absorptive microsampling options have been more extensively studied than other volumetric technologies. Therefore, we suggest that a further investigation and application of the volumetric technologies will contribute to the use of BµS as an alternative to conventional methods. Conversely, we support the idea that harmonisation of the analytical methods when using BµS would have a positive impact on its implementation. [ABSTRACT FROM AUTHOR]

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Objective Real-time reverse transcription-polymerase chain reaction is the gold standard for the diagnosis of COVID-19, but it is necessary to utilize other tests to determine the burden of the disease and the spread of the outbreak such as IgG-, IgM-, and IgA-based antibody detection using enzyme-linked immunosorbent assay (ELISA). Materials and Methods We developed an indirect ELISA assay to quantitatively measure the amount of COVID-19 IgG, IgM, and IgA antibodies present in patient serum, dried blood, and plasma. Results The population cutoff values for positivity were determined by receiver operating characteristic curves to be 1.23 U/mL, 23.09 U/mL, and 6.36 U/mL for IgG, IgM, and IgA, respectively. After albumin subtraction, the specificity remained >98% and the sensitivity was 95.72%, 83.47%, and 82.60%, respectively, for IgG, IgM, and IgA antibodies to the combined spike subunit 1 receptor binding domain and N proteins in serum. Plasma and dried blood spot specimens were also validated on this assay. Conclusion This assay may be used for determining the seroprevalence of SARS-CoV-2 in a population exposed to the virus or in vaccinated individuals. [ABSTRACT FROM AUTHOR]

Background Although populations from low- and middle-income countries are at higher risk for thiamine (vitamin B-1) deficiency, accurate data on the global prevalence of thiamine deficiency are still lacking due to the difficult blood collection in remote regions. Volumetric absorptive microsampling (VAMS) from finger prick blood, generating dried blood microsamples, could simplify blood collection and allow the setup of epidemiological studies to improve the diagnosis, treatment, and prevention of thiamine deficiency. Objectives To explore the potential of VAMS to serve as an alternative, patient-centric sampling strategy to evaluate the thiamine status. Methods Venous liquid, venous VAMS, and capillary VAMS samples were collected from 50 healthy volunteers to compare thiamine diphosphate results, as a marker of thiamine (vitamin B-1) status, in the different sample types. In addition, capillary VAMS samples were sent through regular mail to evaluate the influence of noncontrolled transport on the final results. All samples were analyzed using previously described fully validated LC-MS/MS methods. Results A good agreement (94–100% of the results lying within 20% of their mean) was obtained for all comparisons: venous VAMS compared with venous liquid blood samples, capillary VAMS compared with venous VAMS samples, and capillary VAMS compared with venous liquid blood samples, with no significant bias (maximum mean bias of −1.0%; 95% CI: −4.1%, 2.0%) observed between the different methods. Finally, we demonstrated that VAMS samples can be safely transported through regular mail without affecting the final results. Conclusions VAMS sampling can be used as a reliable alternative tool to evaluate the thiamine status, starting from only one drop of finger prick blood, in both developed and developing countries. [ABSTRACT FROM AUTHOR]

A highly sensitive and specific liquid chromatography‐elctrospray ionization tandem mass spectrometry method was developed and validated for rapid determination of risperidone and its active metabolite in rat dried blood spots and dried plasma spots. Chromatographic separation was achieved through ZIC®‐HILIC (250 × 4.6 mm, 5 µm) at 25°C using 10 mM ammonium acetate (pH: 3.0, adjusted with acetic acid) and acetonitrile (12:88, v/v) as a mobile phase. Tandem mass spectrometry detection was performed in positive ion electrospray ionization using multiple reaction monitoring mode to monitor precursor → product ion transitions m/z 411.2→191.1 for Risperidone, m/z 427.2→207.1 for its metabolite (Risperidone‐9‐OH), respectively. The lower limit of quantification of Risperidone and Risperidone‐9‐OH were 0.95 and 0.90 ng/mL in rat dried blood spots, respectively. The developed bioassay method was successfully applied to study the pharmacokinetic profile of Risperidone and Risperidone‐9‐OH using Iloperidone as an internal standard. As per pharmacokinetic studies, Cmax of Risperidone and Risperidone‐9‐OH in dried blood spots was 36.2 and 28.9 ng/mL; and in dried plasma spots was 38.2 and 30.2 ng/mL, respectively. Similarly, tmax of Risperidone and Risperidone‐9‐OH in dried blood spots was 1.4 and 14.7 h; and in dried plasma spots was 1.54 and 15.4 h, respectively. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) hold great promise as blood-borne and circulating biomarkers for numerous diseases. However, the reliability of such liquid biopsies is particularly impacted by problems associated with the handling of biological liquids in the pre-analytical stage of biomarker processing. Dried blood spots (DBS) and other capillary blood microsampling devices offer a way to circumvent many of these complications. DBS are supposed to be far less sensitive to collection protocols, storage conditions, and transport processes, while offering the possibility for a decentralized sample collection. In addition, DBS are minimally invasive and require very small amounts of blood, thereby facilitating blood collection from small children or patients at risk by blood drawing. Here, we summarize the current state of knowledge about DBS-derived miRNAs. Experimental studies on miRNA from DBS especially emphasize the influence of the adsorptive material and the importance of drying and rehydration protocols. The present studies are, however, difficult to compare as they use different readout-systems, ranging from PCR-based quantification of single miRNAs to next-generation sequencing (NGS) of the entire miRNome. The data underscore the need for procedure standardization and the development of general guidelines on handling and evaluating miRNA biomarkers derived from DBS. [ABSTRACT FROM AUTHOR]

Quantitative metabolite profiling in biological samples has the potential to reflect physiological status and to identify disease associated disturbances in metabolic networks. However, this approach is hampered by a wide range of preanalytical variables. Hence, the aim of our study was to develop a standardized preanalytical protocol for metabolite profiling of amino acids and acylcarnitines in human blood. Amino acids and acylcarnitines were simultaneous analyzed after butylation of 3 μL dried blood or 10 μL whole blood, serum and anticoagulated plasma using electrospray tandem-mass spectrometry. The influence of exogenous and endogenous preanalytical variables was investigated in healthy volunteers. Different sampling materials and anticoagulants for blood taking were investigated. Concentrations of long-chain acylcarnitines were 5-fold higher in EDTA-whole blood or dried whole blood compared to serum and anticoagulated plasma. Significant differences in amino acid concentrations were found for capillary versus venous blood taking. Fasting for 8 h before specimen collection minimized the nutritional influence. Physical activity significantly alters amino acid and short chain acylcarnitine concentrations. As a result of our preanalytical investigation we developed a pre-treatment protocol based on EDTA whole blood dried on filter paper to reduce the preanalytical variability and facilitate reproducible quantitative metabolite profiling in clinical trials. [ABSTRACT FROM AUTHOR]

Background: Changes in the metabolic fingerprint of blood during child growth and development are a largely under-investigated area of research. The examination of such aspects requires a cohort of healthy children and adolescents who have been subjected to deep phenotyping, including collection of biospecimens for metabolomic analysis. The present study considered whether amino acid (AA) and acylcarnitine (AC) concentrations are associated with age, sex, body mass index (BMI), and puberty during childhood and adolescence. It also investigated whether there are associations between amino acids (AAs) and acylcarnitines (ACs) and laboratory parameters of glucose and lipid metabolism, as well as liver, kidney, and thyroid parameters. Methods: A total of 3989 dried whole blood samples collected from 2191 healthy participants, aged 3 months to 18 years, from the LIFE Child cohort (Leipzig, Germany) were analyzed using liquid chromatography tandem mass spectrometry to detect levels of 23 AAs, 6 ACs, and free carnitine (C0). Age- and sex-related percentiles were estimated for each metabolite. In addition, correlations between laboratory parameters and levels of the selected AAs and ACs were calculated using hierarchical models. Results: Four different age-dependent profile types were identified for AAs and ACs. Investigating the association with puberty, we mainly identified peak metabolite levels at Tanner stages 2 to 3 in girls and stages 3 to 5 in boys. Significant correlations were observed between BMI standard deviation score (BMI-SDS) and certain metabolites, among them, branched-chain (leucine/isoleucine, valine) and aromatic (phenylalanine, tyrosine) amino acids. Most of the metabolites correlated significantly with absolute concentrations of glucose, glycated hemoglobin (HbA1c), triglycerides, cystatin C (CysC), and creatinine. After age adjustment, significant correlations were observed between most metabolites and CysC, as well as HbA1c. Conclusions: During childhood, several AA and AC levels are related to age, sex, BMI, and puberty. Moreover, our data verified known associations but also revealed new correlations between AAs/ACs and specific key markers of metabolic function. [ABSTRACT FROM AUTHOR]

Background A consistent and stable source of DNA is an essential requirement for many Biobanks. An important pre-analytical variable is the delay between sample collection and sample processing.Methods Fresh blood samples (n = 80) were collected and either processed immediately or after storage for 24 h. The samples were either stored as liquid blood at 4° C or as dried blood spots at ambient temperature on three types of paper-based storage media. The quality of the DNA extracted from the samples was measured.Results No difference was observed between fresh and stored blood samples.Conclusions The quality of DNA extracted from liquid or dried blood is not adversely affected by storage at 4° C for up to 24 h. [ABSTRACT FROM AUTHOR]