Applications and Diagnostic Potential of Dried Blood Spots

Acceptability of dried blood spot collection by primary caregivers of Filipino patients with maple syrup urine disease (MSUD) and phenylketonuria (PKU)

MSUD and PKU require lifetime management hence, regular monitoring of amino acid levels is needed to achieve good metabolic control. Ideally, plasma amino acid analysis (PLAA) is used to monitor concentrations but is expensive and not widely available in local laboratories. The newborn screening program in the Philippines uses dried blood spot (DBS) analysis as an alternative where only trained healthcare providers are allowed to perform the collection at selected facilities. With the increasing number of patients, DBS monitoring has been noted to be delayed due to multiple factors. This issue became even more evident during the COVID-19 pandemic where high-risk patients need to travel outside for blood collection. The study used a cross-sectional study design to determine the primary caregivers' perspective on DBS self-sampling for patients with MSUD and PKU and the acceptability of the samples collected. This was done through a series of collection training, pre-/post- surveys, and 10-item questionnaire, and an in-depth 1-on-1 interview for thematic analysis. The acceptability of samples was processed and evaluated by the newborn screening laboratory. At-home DBS collection by primary caregivers was found to be acceptable. The provision of knowledge and routine collection training by the medical team aids in the increase of sample acceptability as well as a source of empowerment in being equipped to take care of their child. It is highly recommended that DBS samples collected by caregivers be considered acceptable for more time and cost-saving monitoring of the patients' metabolites. This practice also promotes timely and appropriate management which can lead to better patient health outcomes.

Design and methods of the StepByStep randomized trial of a mobile health and social media physical activity intervention among adolescent and young adult survivors of childhood cancer: A report from the Children's Oncology Group

BACKGROUND

Interventions to increase physical activity are needed in adolescent and young adult survivors of childhood cancer who are largely inactive but at lifelong elevated risk of multiple chronic conditions improved by physical activity. The goals of the StepByStep study are to evaluate the effects of a 48-week distance-based, multi-component mobile health and social media behavioral intervention on physical activity, biomarkers of cardiometabolic health, and health-related quality of life.

METHODS

This ongoing study is a two-arm, prospective, multi-site randomized controlled trial. 384 childhood cancer survivors age ≥ 15 years and < 21 years who were 3-36 months off therapy and not meeting physical activity guidelines were enrolled. The trial will test the efficacy of a 24-week intensive multi-component physical activity intervention combining a wearable physical activity tracker, social media peer support group, and individualized goal setting followed by a 24-week maintenance phase of the intervention to improve outcomes. The control group receives the wearable physical activity tracker only.

CONCLUSION

There is a growing need for novel, developmentally appropriate interventions to increase physical activity and improve the health trajectory of adolescent and young adult survivors of childhood cancer. If efficacious, this portable and scalable intervention would be a much-needed tool to reduce the morbidity from cancer treatment and improve quality of life among survivors after treatment ends.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04089358; COG Identifier: ALTE2031.

Clinical performance and application of novel serum collection "Ser-Col" device in the practice of laboratory diagnosis of infection diseases and several other immunochemical tests

BACKGROUND

Dried blood collection devices might be beneficial for diagnosing infectious diseases in areas far from the medical facilities and in lockdown situations. There are several reports on the efficacy of such applications for qualitative tests. Here we demonstrated the feasibility of a novel Ser-Col blood collection device as a standardized approach for qualitative and quantitative detection of infectious markers and several over immunochemical tests.

METHODS

In the current study, we included 395 adult participants, 191 men and 204 women, with a median age of 41 years, as well as 75 children with a median age of 3 years. Serological status was determined by testing serum samples for three groups of infection diseases: hepatitis A and C, SARS-CoV-2, and herpes family viruses, as well as for thyroid peroxidase (TPO), prolactin, vitamin B12, and folate. Blood collected on the Ser-Col device (Labonovum) was eluted using an automated system (SCAUT Ser-Col automation, Blok System Supply) and manually. Ser-Col results were compared with serum sampled via standard venipuncture considered as the reference.

RESULTS

High correlation coefficients (r = 0.95-0.99) were observed between serum samples collected with Ser-Col and via standard venipuncture for the following tests: anti-HCV, anti-SARS-CoV-2 IgG, anti-HSV-2 IgG, and anti-CMV IgM. Correlation coefficients between Ser-Col and standard venipuncture serum for anti-HSV-1 IgG, anti-CMV IgG, and anti-EBV tests were relatively low (r = 0.73-0.77). Correlation coefficients for anti-TPO, prolactin, vitamin B12, and folate were also characterized with high values (r = 0.97-0.99).

CONCLUSIONS

High accuracy and quantitative correlation were demonstrated between Ser-Col and samples collected by standard venipuncture. Hence, the Ser-Col blood collection device should be considered as a promising alternative for blood collection, storage, and transportation in both adult and pediatric populations.

A simplified metabolomic analysis of dried blood spots in breast cancer patients

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.

Molecular Detection of Tick-Borne Pathogens in Kumasi: With a First Report of Zoonotic Pathogens in Abattoir Workers

Tick-borne pathogens continue to infect humans and animals worldwide. By adapting to the movement of livestock, ticks facilitate the spread of these infectious pathogens. Humans in close contact with animals that could be amplifying hosts are especially at risk of being infected with tick-borne pathogens. This study involved the collection of dry blood spots (DBSs) to determine tick-borne pathogens occurring in slaughtered livestock and abattoir workers in Kumasi. This study employed the use of conventional PCR, RT-PCR, and Sanger sequencing to detect and identify the tick-borne pathogens. The resulting data was analysed using Stata version 13. A total of 175 DBSs were collected from goats (76), cattle (54), and sheep (45) in the Kumasi abattoir (130, 74.29%) and Akwatia Line slaughter slab (45, 25.71%). The pathogens identified were mostly bacterial including Anaplasma capra (9.71%), Anaplasma phagocytophilum (1.14%), and Rickettsia aeschlimannii (0.57.%). The only parasite identified was Theileria ovis (9.14%). A significant association was seen between A. capra (p < 0.001) infection and female sheep sampled from the Akwatia Line slaughter slab. Again, there was a significant association between T. ovis (p < 0.001) infections and female sheep from the Kumasi abattoir. From the human DBS (63) screened, the pathogens identified were all bacterial including Coxiella burnetii (1.89%), Rickettsia africae (1.89%), and R. aeschlimannii (1.89%). This study reports the first detection of R. aeschlimannii in livestock as well as the occurrence of the above-mentioned pathogens in humans in Ghana. Animals can serve as amplifying hosts for infectious pathogens; hence, there is an increased risk of infections among the abattoir workers. Continuous surveillance effort is essential, and abattoir workers need to protect themselves from tick bites and infectious tick-borne pathogens.

Repurposing dried blood spot device technology to examine bile acid profiles in human dried fecal spot samples

Dried blood spot (DBS) analysis has existed for >50 years, but application of this technique to fecal analysis remains limited. To address whether dried fecal spots (DFS) could be used to measure fecal bile acids, we collected feces from five subjects for each of the following cohorts: 1) healthy individuals, 2) individuals with diarrhea, and 3) Clostridioides difficile-infected patients. Homogenized fecal extracts were loaded onto quantitative DBS (qDBS) devices, dried overnight, and shipped to the bioanalytical lab at ambient temperature. For comparison, source fecal extracts were shipped on dry ice and stored frozen. After 4 mo, frozen fecal extracts and ambient DFS samples were processed and subjected to targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics with stable isotope-labeled standards. We observed no differences in the bile acid levels measured between the traditional extraction and the qDBS-based DFS methods. This pilot data demonstrates that DFS-based analysis is feasible and warrants further development for fecal compounds and microbiome applications.NEW & NOTEWORTHY Stool analysis in remote settings can be challenging, as the samples must be stored at -80°C and transported on dry ice for downstream processing. Our work indicates that dried fecal spots (DFS) on Capitainer quantitative DBS (qDBS) devices can be stored and shipped at ambient temperature and yields the same bile acid profiles as traditional samples. This approach has broad applications for patient home testing and sample collection in rural communities or resource-limited countries.

Dried blood spot analysis for elements of nutritional concern as demonstrated in studies of Galápagos land iguanas (Conolophus species)

BACKGROUND

Dried blood spot (DBS) technology is valuable in providing simple means of storing blood samples from wildlife with small blood volumes. Methods designed for heavy metal analysis on DBS become more useful if extended to elements of nutritional significance.

PURPOSE

(1) Development of procedures for measuring Mn, Fe, Co, Cu, Zn, Se and Mo in DBS; (2) use the designed methods in health assessments of Galápagos land iguanas (Conolophus species).

PROCEDURES

Elements were measured by inductively coupled plasma/mass spectrometry (ICP-MS) following acid digestion of whole blood or DBS from the same animal for direct comparison. Study animals comprised free-ranging iguanas from separate islands in the Galápagos archipelago.

MAIN FINDINGS

DBS spikes (Mn, Fe, Co, Cu, Zn, Se and Mo) demonstrated accuracy to ∼100 ppb; reporting limits were set there except for Fe and Zn which were set at 1000 ppb. Plasma samples - generally preferable for nutritional element diagnostics - were submitted from Galápagos land iguanas along with DBS as part of a large-scale health assessment. In plasma versus DBS concentration comparisons, Fe, Cu, Se and Mn correlated well with R^2 values of 0.799, 0.818, 0.896 and 0.899, respectively, and slopes ranging 0.88 - 1.3. Co and Zn showed greater scatter. Mo had insufficient points above its reporting limit and offered advantages for toxicity assessments. Bland-Altman diagrams showed flat scatter between 2x standard deviation boundaries with no undue trends except for Mn which had few points above its reporting limit. Bias, defined as the average difference [DBS - plasma] divided by the average value, was relatively low throughout, with values of - 19.3 % (Fe), - 48.7 % (Co), - 19.6 % (Cu), - 6.9 % (Zn), - 21.4 % (Se) and + 40.7 % (Mn). Normal distribution assessment of iguana Cu, Zn, Se and Fe plasma values showed unanticipated divergences between two species.

CONCLUSIONS

The DBS approach for nutritional element analysis offers a suitable methodology for determining crucial elements Mn, Fe, Co, Cu, Zn, Se, and Mo in veterinary samples. Analyses of samples from Conolophus species revealed interesting divergences particularly for Cu, Zn, Se and Fe, elements generally associated with defense against oxidative stress.

Harmonization of distributed multi-center analysis based on dried blood spot reference materials supporting the screening of neonatal inherited metabolic disorders

BACKGROUND

The standardization of quantification data is critical for ensuring the reliability and measurement traceability in the screening of neonatal inherited metabolic disorders. However, the availability of national certified reference materials is limited in China.

METHODS

In this study, we developed a series of dried blood spot (DBS) reference materials containing 9 amino acids (AA) and 10 acylcarnitines (AC) for neonatal screening. Four levels of the reference materials were measured with tandem mass spectrometry (MS/MS) by seven laboratories using different commercial In Vitro Diagnostic Device (IVD) kits. Then, 100 clinical samples were measured using both derivatization and non-derivatization methods by the same laboratory.

RESULTS

We found high homogeneity and stability at all levels of the reference materials, with the coefficient of variation (CV) of the analytes less than 15%. These reference materials can be used to assess the testing capabilities of different laboratories. Our test also revealed that the correction factors (CF) calculated by the reference materials, along with clinical samples, could increase the consistency for different kits.

CONCLUSION

The DBS reference materials proposed in this study provide reliability for the harmonization in multi-center analysis for the screening of neonatal inherited metabolic disorders. And applying our correction method for the screening could improve the data consistency of the DBS samples prepared by different methods.

Dried Blood Spots-A Platform for Therapeutic Drug Monitoring (TDM) and Drug/Disease Response Monitoring (DRM)

This review provides an overview on the current applications of dried blood spots (DBS) as matrices for therapeutic drug (TDM) and drug or disease response monitoring (DRM). Compared with conventional methods using plasma/serum, DBS offers several advantages, including minimally invasiveness, a small blood volume requirement, reduced biohazardous risk, and improved sample stability. Numerous assays utilising DBS for TDM have been reported in the literature over the past decade, covering a wide range of therapeutic drugs. Several factors can affect the accuracy and reliability of the DBS sampling method, including haematocrit (HCT), blood volume, sampling paper and chromatographic effects. It is crucial to evaluate the correlation between DBS concentrations and conventional plasma/serum concentrations, as the latter has traditionally been used for clinical decision. The feasibility of using DBS sampling method as an option for home-based TDM is also discussed. Furthermore, DBS has also been used as a matrix for monitoring the drug or disease responses (DRM) through various approaches such as genotyping, viral load measurement, assessment of inflammatory factors, and more recently, metabolic profiling. Although this research is still in the development stage, advancements in technology are expected to lead to the identification of surrogate biomarkers for drug treatment in DBS and a better understanding of the correlation between DBS drug levels and drug responses. This will make DBS a valuable matrix for TDM and DRM, facilitating the achievement of pharmacokinetic and pharmacodynamic correlations and enabling personalised therapy.

Safety of medicines during breastfeeding - from case report to modeling : A contribution from the ConcePTION project

INTRODUCTION

Despite many research efforts, current data on the safety of medicines during breastfeeding are either fragmented or lacking, resulting in restrictive labeling of most medicines. In the absence of pharmacoepidemiologic safety studies, risk estimation for breastfed infants is mainly derived from pharmacokinetic (PK) information on the medicine. This manuscript provides a description and a comparison of the different methodological approaches that can yield reliable information on medicine transfer into human milk and the resulting infant exposure.

AREA COVERED

Currently, most information on medicine transfer in human milk relies on case reports or traditional PK studies, which generate data that can hardly be generalized to the population. Some methodological approaches, such as population PK (popPK) and physiologically-based PK (PBPK) modeling, can be used to provide a more complete characterization of infant medicine exposure through human milk and simulate the most extreme situations, while decreasing the burden of sampling in breastfeeding women.

EXPERT OPINION

PBPK and popPK modeling are promising approaches to fill the gap of knowledge in medicine safety in breastfeeding, as illustrated with our escitalopram example.

Development and validation of an LC-MS/MS assay for the quantitative analysis of alprazolam, α-hydroxyalprazolam and hydrocodone in dried blood spots

Dried blood spot (DBS) has been used as an alternative matrix in drug testing. In forensic testing it offers enhanced stability of analytes and ease of storage that requires minimal space. This is compatible with long term archiving of large numbers of samples for future investigation. We employed liquid chromatography-tandem mass spectrometry (LC-MS/MS) to quantify alprazolam, α-hydroxyalprazolam, and hydrocodone in a DBS sample that has been stored for 17 years. We achieved linear dynamic ranges (0.1-50 ng/mL) that capture wide ranges of concentration of the analytes below and above their reported reference ranges, and limits of detection (0.05 ng/mL) of 40-100X lower than the lower limit of the analyte's reference ranges. The method was validated according to FDA and CLSI guidelines and successfully confirmed and quantified alprazolam and α-hydroxyalprazolam in a forensic DBS sample.

Design, Synthesis, Anti-Tubercular Evaluation and Teratogenicity Studies of Furanyl Pyrazolo[3,4-b] Quinoline-5-Ones

We have synthesized novel pyrazolo-quinoline analogues (P1-10) in an effort to create newer antitubercular drugs against the rising bacterial resistance. NMR, IR and ESI-MS spectra were utilized to characterize the synthesised compounds. The antitubercular activity of the target compounds was evaluated against Mycobacterium tuberculosis. Six derivatives (P1-6) displayed very significant activity at 1.6 µg/mL concentration and were found to be more active than pyrazinamide standard. Thus, as per the drug susceptibility results the MIC value could be considered between 1.6 and 0.8 µg/mL. In addition, all the synthesised compounds were subjected to molecular docking studies against specific protein, Enoyl acyl carrier protein reductase (InhA) in complex with N-(4-methylbenzoyl)-4-benzylpiperidine, PDB ID: 2NSD. Among all the compounds the most effective compounds were found an Autodock score of 11.6 and 11.2 against 2NSD, respectively. Further, Zebrafish larvae have been used to test the teratogenicity of the synthesised compounds. There were no indications of abnormalities with (P2), (P4), (P5), (P6), and (P10) at 0.5 µM.

Supplementary Information

The online version contains supplementary material available at 10.1134/S1068162023010053.

Patterned Dried Blood Spot Cards for the Improved Sampling of Whole Blood

Dried blood spot (DBS) cards perform many functions for sampling blood that is intended for subsequent laboratory analysis, which include: (i) obviating the need for a phlebotomist by using fingersticks, (ii) enhancing the stability of analytes at ambient or elevated environmental conditions, and (iii) simplifying the transportation of samples without a cold chain. However, a significant drawback of standard DBS cards is the potential for sampling bias due to unrestricted filling caused by the hematocrit of blood, which often limits quantitative or reproducible measurements. Alternative microsampling technologies have minimized or eliminated this bias by restricting blood distribution, but these approaches deviate from clinical protocols and present a barrier to broad adoption. Herein, we describe a patterned dried blood spot (pDBS) card that uses wax barriers to control the flow and restrict the distribution of blood to provide enhanced sampling. These patterned cards reproducibly fill four replicate extraction zones independent of the hematocrit effect. We demonstrate a 3-fold improvement in accuracy for the quantitation of hemoglobin using pDBS cards compared to unpatterned cards. Patterned cards also facilitate the near quantitative recovery (ca. 95%) of sodium with no evidence of a statistically significant difference between dried and liquid blood samples. Similarly, the recovery of select amino acids was conserved in comparison to a recent report with improved intercard precision. We anticipate that this approach presents a viable method for preparing and storing samples of blood in limited resource settings while maintaining current clinical protocols for processing and analyzing dried blood spots.

Evaluation of three different rapid card tests for the detection of hepatitis B surface antigen

Rapid diagnostic card tests are crucial steps on the road to hepatitis B elimination and should be incorporated into diagnostic algorithms. However, all commercial rapid diagnostic card tests are not equal and require evaluation before clinical use. Thus, we aimed to compare the performance characteristics of three different rapid diagnostic card tests with chemiluminescence-based assay (CLIA) for the detection of hepatitis B surface antigen.We concluded rapid diagnostic card tests can be used to identify patients with high signal/cut-off ratio on CLIA, but patients with signal/cut-off ratio <200 may be missed. Rapid diagnostic card tests may help pave the way for decentralised testing, but should be used only after evaluation in the community.

Dried Blood Spot in Toxicology: Current Knowledge

Dried Blood Spot (DBS) is becoming very popular in various medical fields, especially in toxicology. Nowadays it is commonly used in newborn screening for inherited or congenital diseases. This paperwork is based on a review of available literature. DBS is simple and rapid, it does not require trained medical staff to collect the samples. Specimens can be easily and safely transported to the laboratory. DBS provides an opportunity for roadside testing and rather quick results. Venous blood spot, collected from a finger or a heel, is put on the special paper card, which can result in a different distribution of blood and concentration of detecting substances. Marking multiple substances from one spot is extremely challenging, but due to further advancements in this area, it is only a matter of time until it becomes possible and all the disadvantages vanish. DBS is certain to develop and become even more worldwide used.

7-Ketocholesterol: Effects on viral infections and hypothetical contribution in COVID-19

7-Ketocholesterol, which is one of the earliest cholesterol oxidization products identified, is essentially formed by the auto-oxidation of cholesterol. In the body, 7-ketocholesterol is both provided by food and produced endogenously. This pro-oxidant and pro-inflammatory molecule, which can activate apoptosis and autophagy at high concentrations, is an abundant component of oxidized Low Density Lipoproteins. 7-Ketocholesterol appears to significantly contribute to the development of age-related diseases (cardiovascular diseases, age-related macular degeneration, and Alzheimer's disease), chronic inflammatory bowel diseases and to certain cancers. Recent studies have also shown that 7-ketocholesterol has anti-viral activities, including on SARS-CoV-2, which are, however, lower than those of oxysterols resulting from the oxidation of cholesterol on the side chain. Furthermore, 7-ketocholesterol is increased in the serum of moderately and severely affected COVID-19 patients. In the case of COVID-19, it can be assumed that the antiviral activity of 7-ketocholesterol could be counterbalanced by its toxic effects, including pro-oxidant, pro-inflammatory and pro-coagulant activities that might promote the induction of cell death in alveolar cells. It is therefore suggested that this oxysterol might be involved in the pathophysiology of COVID-19 by contributing to the acute respiratory distress syndrome and promoting a deleterious, even fatal outcome. Thus, 7-ketocholesterol could possibly constitute a lipid biomarker of COVID-19 outcome and counteracting its toxic effects with adjuvant therapies might have beneficial effects in COVID-19 patients.

Validation of a combined ELISA to detect IgG, IgA and IgM antibody responses to SARS-CoV-2 in mild or moderate non-hospitalised patients

BACKGROUND

Frequently SARS-CoV-2 results in mild or moderate disease with potentially lower concentrations of antibodies compared to those that are hospitalised. Here, we validated an ELISA using SARS-CoV-2 trimeric spike glycoprotein, with targeted detection of IgG, IgA and IgM (IgGAM) using serum and dried blood spots (DBS) from adults with mild or moderate disease.

METHODS

Targeting the SARS-CoV-2 trimeric spike, a combined anti-IgG, IgA and IgM serology ELISA assay was developed using 62 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 624 COVID-19 negative samples. The assay was validated using 73 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 359 COVID-19 negative serum samples with an additional 81 DBSs. The assay was further validated in 226 PCR-confirmed non-hospitalised, mild or moderate COVID-19 samples, ≥14 days post symptom onset and 426 COVID-19 negative clinical samples.

RESULTS

A sensitivity and specificity of 98.6% (95% CI, 92.6-100.0), 98.3% (95% CI, 96.4-99.4), respectively, was observed following validation of the SARS-CoV-2 ELISA. No cross-reactivities with endemic coronaviruses or other human viruses were observed, and no change in results were recorded for interfering substances. The assay was stable at temperature extremes and components were stable for 15 days once opened. A matrix comparison showed DBS to correlate with serum results. Clinical validation of the assay reported a sensitivity of 94.7% (95% CI, 90.9-97.2%) and a specificity of 98.4% (95% CI, 96.6-99.3%).

CONCLUSIONS

The human anti-IgGAM SARS-CoV-2 ELISA provides accurate and sensitive detection of SARS-CoV-2 antibodies in non-hospitalised adults with mild or moderate disease. The use of dried blood spots makes the assay accessible to the wider community.

A newborn screening pilot study using methylation-sensitive high resolution melting on dried blood spots to detect Prader-Willi and Angelman syndromes

Prader-Willi (PWS) and Angelman (AS) syndromes are two clinically distinct imprinted disorders characterized by genetic abnormalities at 15q11-q13. Early diagnosis of both syndromes provides improved treatment and accurate genetic counseling. Whole blood (WB) is the most common DNA source of many methodologies to detect PWS and AS, however, the need of WB makes a massive screening difficult in newborns due to economic and technical limitations. The aim of this study was to adapt a Methylation-sensitive High-Resolution Melting (MS-HRM) approach from dried blood spot (DBS) samples, assessing the different DNA isolation techniques and diagnostic performance. Over a 1-year period, we collected 125 DBS cards, of which 45 had already been diagnosed by MS-HRM (20 PWS, 1 AS, and 24 healthy individuals). We tested three different DBS-DNA extraction techniques assessing the DNA concentration and quality, followed by MS-HRM and statistical comparison. Each DBS-DNA extraction method was capable of accuracy in detecting all PWS and AS individuals. However, the efficiency to detect healthy individuals varied according to methodology. In our experience, DNA extracted from DBS analyzed by the MS-HRM methodology provides an accurate approach for genetic screening of imprinting related disorders in newborns, offering several benefits compared to traditional whole blood methods.

The potential of neurofilaments analysis using dry-blood and plasma spots

The lack of biomarkers for an early diagnosis of neurodegenerative disorders (NDs) has hampered the development of therapeutics whose effect would be enhanced by a timely intervention. Neurofilaments light chain (Nf-L), an integral part of the axonal structure, has emerged as a robust fluid biomarker for fatal neurodegenerative disorders like amyotrophic lateral sclerosis (ALS). To facilitate large-scale studies into early-stage neurodegeneration, reduce costs of samples collection/processing and cold-chain storage, we describe the measurement of Nf-L in blood fractions obtained from dry blood spots (DBS) and dry plasma spots (DPS), two filter paper-based remote blood collection tools. To test the feasibility of using this approach, Nf-L analysis in DBS/DPS is compared to that in plasma obtained from the same blood sample, looking at Nf-L discriminatory power in the clinical stratification of ALS compared to healthy controls. With the best pre-analytical treatment for total protein recovery and using highly sensitive immunoassays, we report the detection of different Nf-L levels in DBS elute compared to reference plasma and DPS from the same blood samples. However, Nf-L measurement in DBS elutes provides a very good discrimination of ALS from healthy controls which is comparable to that obtained using plasma Nf-L assays. With the available immunodetection methods, we show that Nf-L measurement based on DPS microsampling is similar to that in plasma. The filter-paper biophysical characteristics and the interference of high haemoglobin concentration released by erythrocyte lysis is likely to perturb Nf-L detection in DBS elute. Further studies into DBS-based Nf-L detection and its analytical optimization are needed to make this method suitable for routine Nf-L blood analyses in neurodegeneration.

A Dried Blood Spot Analysis for Solithromycin in Adolescents, Children, and Infants: A Short Communication

BACKGROUND

Solithromycin is a fourth-generation macrolide antibiotic with potential efficacy in pediatric community-acquired bacterial pneumonia. Pharmacokinetic (PK) studies of solithromycin in pediatric subjects are limited, therefore application of minimally invasive drug sampling techniques, such as dried blood spots (DBS), may enhance the enrollment of children in PK studies. The objectives of this study were to compare solithromycin concentrations in DBS with those in liquid plasma samples (LPS) and to quantify the effects of modeling DBS concentrations on the results of a population PK model.

METHODS

Comparability analysis was performed on matched DBS and LPS solithromycin concentrations collected from two different phase 1 clinical trials of solithromycin treatment in children (clinicaltrials.gov #NCT01966055 and #NCT02268279). Comparability of solithromycin concentrations was evaluated based on DBS:LPS ratio, median percentage prediction error, and median absolute percentage prediction error. The effect of correcting DBS concentrations for both hematocrit and protein binding was investigated. In addition, a previously published population PK model (NONMEM) was leveraged to compare parameter estimates resulting from either DBS or LPS concentrations.

RESULTS

A total of 672 paired DBS-LPS concentrations were available from 95 subjects (age: 0-17 years of age). The median (range) LPS and DBS solithromycin concentrations were 0.3 (0.01-12) mcg/mL and 0.32 (0.01-14) mcg/mL, respectively. Median percentage prediction error and median absolute percentage prediction error of raw DBS to LPS solithromycin concentrations were 5.26% and 22.95%, respectively. In addition, the majority of population PK parameter estimates resulting from modeling DBS concentrations were within 15% of those obtained from modeling LPS concentrations.

CONCLUSIONS

Solithromycin concentrations in DBS were similar to those measured in LPS and did not require correction for hematocrit or protein binding.

Midbody of the medial meniscus as a reference of preservation in partial meniscectomy for complete discoid lateral meniscus

PURPOSE

To evaluate the postoperative size of discoid lateral meniscus using magnetic resonance imaging (MRI) after partial meniscectomy relative to the size of medial meniscus midbody.

METHODS

This study included 48 patients who underwent arthroscopic partial meniscectomy with or without repair for symptomatic complete discoid meniscus. The intraoperative size of midbody of medial meniscus was used as a reference for partial meniscectomy. MRIs were performed pre- and postoperatively. Quantitative evaluations of the height, width, extrusion of the meniscus, and relative percentage of extrusion in the coronal and sagittal planes were completed. Demographic data, preoperative shift, type of shift, and operative technique were analyzed while considering the remaining meniscus. Logistic regression analyses were used.

RESULTS

The mean remaining discoid meniscal width in the coronal plane of MRI was not significantly different from the width of midbody of medial meniscus (9.1 ± 4.2 mm vs. 9.4 ± 1.4 mm, n.s.) Absolute meniscal extrusion and relative percentage of extrusion in the coronal plane and the ratio of t meniscus in sagittal plane of the final MRI were significantly increased as compared with the preoperative MRI. Preoperative shift was a risk factor for the reduction of remaining meniscal width (odds ratio 11.997, p = 0.016, 95% CI 1.586-90.737).

CONCLUSION

The size of midbody of medial meniscus could be a reference for partial meniscectomy in symptomatic complete discoid meniscus. Preoperative shift represents a risk factor for decreased remaining meniscal width. These findings could be helpful in ensuring appropriate surgical planning and explaining poor prognostic factors.

LEVEL OF EVIDENCE

Prospective cohort study, Level II.