Project description:Measurement of telomere length is crucial for the study of telomere maintenance and its role in molecular pathophysiology of diseases and in aging. Several methods are used to measure telomere length, the choice of which usually depends on the type and size of sample to be assayed, as well as cost and throughput considerations. The goal of this study was to investigate the factors that may influence the reliability of qPCR-based relative telomere length measurements in whole blood. Day to day intra-individual variability, types of blood anticoagulant, sample storage conditions, processing and site of blood draw were investigated. Two qPCR-based methods to measure telomere length (monoplex vs. multiplex) were also investigated and showed a strong correlation between them. Freezing and thawing of the blood and storage of the blood at 4°C for up to 4 days did not affect telomere length values. Telomere lengths in dried blood spots were significantly higher than both whole blood and peripheral mononuclear blood cells, and were highly correlated with both. We found that telomere length measurements were significantly higher in dried blood spots collected directly from fingertip prick compared to dried blood spots prepared with anticoagulated whole blood collected from the finger, and non-blotted whole blood taken from both finger and arm venipuncture. This suggests that DNA from cells blotted on paper is not equivalent to that collected from venipuncture whole blood, and caution should be taken when comparing between blood sample types.
Project description:ObjectivesThe quality of blood values analyzed from survey-collected dried blood spot (DBS) samples is affected by fieldwork conditions, particularly spot size. We offer an image-based algorithm that accurately measures the area of field-collected DBS and we investigate the impact of spot size on the analyzed blood marker values.MethodsSHARE, a pan-European study, collected 24 000 DBS samples in 12 countries in its sixth wave. Our new algorithm uses photographs of the DBS samples to calculate the number of pixels of the blood-covered area to measure the spot sizes accurately. We ran regression models to examine the association of spot size and seven DBS analytes. We then compared the application of our new spot-size measures to common spot-size estimation.ResultsUsing automated spot-size measurement, we found that spot size has a significant effect on all markers. Smaller spots are associated with lower measured levels, except for HbA1c, for which we observe a negative effect. Our precisely measured spot sizes explain substantially more variance of DBS analytes compared to commonly used spot-size estimation.ConclusionThe new algorithm accurately measures the size of field-collected DBS in an automated way. This methodology can be applied to surveys even with very large numbers of observations. The measured spot sizes improve the accuracy of conversion formulae that translate blood marker values derived from DBS into venous blood values. The significance of the spot-size effects on biomarkers in DBS should also incentivize the improvement of fieldwork training and monitoring.
Project description:BackgroundIncreasingly, vaccine efficacy studies are being recommended in low-and-middle-income countries (LMIC), yet often facilities are unavailable to take and store infant blood samples correctly. Dried blood spots (DBS), are useful for collecting blood from infants for diagnostic purposes, especially in low-income settings, as the amount of blood required is miniscule and no refrigeration is required. Little is known about their utility for antibody studies in children. This systematic review aims to investigate the correlation of antibody concentrations against infectious diseases in DBS in comparison to serum or plasma samples that might inform their use in vaccine clinical trials.Methods and findingsWe searched MEDLINE, Embase and the Cochrane library for relevant studies between January 1990 to October 2020 with no language restriction, using PRISMA guidelines, investigating the correlation between antibody concentrations in DBS and serum or plasma samples, and the effect of storage temperature on DBS diagnostic performance. We included 40 studies in this systematic review. The antibody concentration in DBS and serum/plasma samples reported a good pooled correlation, (r2 = 0.86 (ranged 0.43 to 1.00)). Ten studies described a decline of antibody after 28 days at room temperature compared to optimal storage at -20°C, where antibodies were stable for up to 200 days. There were only five studies of anti-bacterial antibodies.ConclusionsThere is a good correlation between antibody concentrations in DBS and serum/plasma samples, supporting the wider use of DBS in vaccine and sero-epidemiological studies, but there is limited data on anti-bacterial antibodies. The correct storage of DBS is critical and may be a consideration for longer term storage.
Project description:The preferred sampling medium for measuring human exposures of persistent organic compounds (POPs) is blood, and relevant sample types include whole blood, plasma, and dried blood spots (DBS). Because information regarding the performance and comparability of measurements across these sample types is limited, it is difficult to compare across studies. This study evaluates the performance of POP measurements in plasma, whole blood and DBS, and presents the distribution coefficients needed to convert concentrations among the three sample types. Blood samples were collected from adult volunteers, along with demographic and smoking information, and analyzed by GC/MS for organochlorine pesticides (OCPs), chlorinated hydrocarbons (CHCs), polychlorinated biphenyls (PCBs), and brominated diphenyl ethers (PBDEs). Regression models were used to evaluate the relationships between the sample types and possible effects of personal covariates. Distribution coefficients also were calculated using physically-based models. Across all compounds, concentrations in plasma were consistently the highest; concentrations in whole blood and DBS samples were comparable. Distribution coefficients for plasma to whole blood concentrations ranged from 1.74 to 2.26 for pesticides/CHCs, averaged 1.69 ± 0.06 for the PCBs, and averaged 1.65 ± 0.03 for the PBDEs. Regression models closely fit most chemicals (R (2) > 0.80), and whole blood and DBS samples generally showed very good agreement. Distribution coefficients estimated using biologically-based models were near one and did not explain the observed distribution. Among the study population, median concentrations of several pesticides/CHCs and PBDEs exceeded levels reported in the 2007-2008 National Health and Nutrition Examination Survey, while levels of other OCPs and PBDEs were comparable or lower. Race and smoking status appeared to slightly affect plasma/blood concentration ratios for several POPs. The experimentally-determined distribution coefficients can be used to compare POP exposures across studies using different types of blood-based matrices.
Project description:Able to seqence microRNA from 2 x 6 mm dired blood spot chads from the BIBINS study. Samples are from newborns with moderate-severe HIE undergoing therapeutic hypothermia at around 16-24 h post insult, mild HIE without therapeutic hypothermia, and umbilical cord blodd from normal pregnancies.
Project description:Nicotinamide adenine dinucleotide (NAD+) is a coenzyme essential for energy production. Recently, associations between NAD+ and aging-related diseases have been reported, and NAD+ precursors that increase NAD+ concentration in the body have been acknowledged as anti-aging supplements. However, there have been only a few studies on the link between aging or aging-related diseases and human blood NAD+ concentration because NAD+ and its precursors are unstable in blood and difficult to measure. Therefore, we aimed to construct a quantitative NAD+ measurement method that is simpler than the existing methods. The calibration standards of NAD+ showed good linearity (0.9936 to 0.9990) in the range of 0.25 to 200 μM, and the lower limit of quantification was 0.5 to 2 μM. We found that QIAcard FTA DMPK-B maintained NAD+ stability of 85% or more for at least 2 weeks at 4 °C and 1 week at room temperature using the dried blood spot method. Additionally, NAD+ stability in the blood extraction solution was more than 90% for 2 months. To our knowledge, there has been no report on a quantitative NAD+ measurement method in human whole blood that can be performed with as little as 5 μL of blood and can be easily implemented at both medical clinics and private homes. Our simple and convenient method has the potential to become the gold standard for NAD+ measurement in blood. It is expected to contribute to the acceleration of research on the correlation between aging or aging-related diseases and NAD+ concentration in human blood.
Project description:Testosterone is a critical hormone involved in regulating various physiological processes in both men and women. Accurate testosterone measurement is essential for diagnosing endocrine disorders such as hypogonadism and polycystic ovary syndrome and for routine testing. Traditionally, testosterone levels are measured using serum or plasma samples, which present challenges in sample collection, storage, and transport, particularly in resource-limited settings. Dried blood spot (DBS) sampling has emerged as an effective alternative for hormone analysis, offering significant advantages in terms of sample stability, ease of collection, and simplified logistics. This study aimed to validate a DBS-based testosterone assay using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to ensure accuracy and precision comparable to conventional serum-based methods. Drops of whole blood samples were collected from adult volunteers using a single-use safety lancet for finger pricks, with blood applied onto DBS cards (PerkinElmer 226 Spot Saver RUO card) for further analysis. The testosterone was extracted from DBS using a liquid-liquid method and analyzed with LC-MS/MS. The assay demonstrated excellent linearity across a wide concentration range (0.1-100 ng/mL) with a correlation coefficient (r2) of 0.999 and achieved a lower limit of detection of 0.058 ng/mL and a lower limit of quantification of 0.086 ng/mL. The method showed high precision, with intra- and inter-day coefficients of variation below 10%, and satisfactory recovery rates. Hematocrit correction and matrix effect evaluations confirmed the robustness of the assay for clinical and research applications. Additionally, the assay displayed a strong clinical correlation between testosterone levels in DBS and venous serum samples, supporting its reliability for testosterone monitoring. This validation study supports that the DBS-based LC-MS/MS testosterone assay is a reliable tool for testosterone quantification for routine testing.
Project description:Comparison of transcript abundance estimates and bioinformatic inferences derived from DBS vs PAXgene vs peripheral blood mononuclear cell (PBMC) samples.
Project description:An important motivation for the construction of biobanks is to discover biomarkers that identify diseases at early, potentially curable stages. This will require biobanks from large numbers of individuals, preferably sampled repeatedly, where the samples are collected and stored under conditions that preserve potential biomarkers. Dried blood samples are attractive for biobanking because of the ease and low cost of collection and storage. Here we have investigated their suitability for protein measurements. Ninety-two proteins with relevance for oncology were analyzed using multiplex proximity extension assays (PEA) in dried blood spots collected on paper and stored for up to 30 years at either +4 °C or -24 °C.Our main findings were that (1) the act of drying only slightly influenced detection of blood proteins (average correlation of 0.970), and in a reproducible manner (correlation of 0.999), (2) detection of some proteins was not significantly affected by storage over the full range of three decades (34 and 76% of the analyzed proteins at +4 °C and -24 °C, respectively), whereas levels of others decreased slowly during storage with half-lives in the range of 10 to 50 years, and (3) detectability of proteins was less affected in dried samples stored at -24 °C compared with at +4 °C, as the median protein abundance had decreased to 80 and 93% of starting levels after 10 years of storage at +4 °C or -24 °C, respectively. The results of our study are encouraging as they suggest an inexpensive means to collect large numbers of blood samples, even by the donors themselves, and to transport, and store biobanked samples as spots of whole blood dried on paper. Combined with emerging means to measure hundreds or thousands of protein, such biobanks could prove of great medical value by greatly enhancing discovery as well as routine analysis of blood biomarkers.
Project description:Over the past few years, dried blood spot (DBS) technology has become a convenient tool in both qualitative and quantitative biological analysis. DBS technology consists of a membrane carrier (MC) on the surface of which a biomaterial sample becomes absorbed. Modern analytical, immunological or genomic methods can be employed for analysis after drying the sample. DBS has been described as the most appropriate method for biomaterial sampling due to specific associated inherent advantages, including the small volumes of biomaterials required, the absence of a need for special conditions for samples' storage and transportation, improved stability of analytes and reduced risk of infection resulting from contaminated samples. This review illustrates information on the current state of DBS technology, which can be useful and helpful for biomedical researchers. The prospects of using this technology to assess the metabolomic profile, assessment, diagnosis of communicable diseases are demonstrated.