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The limitations of many in situ microsampling techniques, especially when applied to isotopic analyses, may result in lower measurement precision and limit the ability to compare different isotope systems within the same phase or the same isotope system between phases. High‐precision, combined and complementary isotopic measurements are typically limited to whole‐rock samples or mineral separates at the expense of textural context. We demonstrate that laser ablation instruments could offer an effective, non‐mechanical alternative to micro‐milling for delineating and extracting single crystals, interstitial phases, and sub‐crystal scale features from soluble‐resin thick sections for column chromatography and high precision ID‐TIMS measurement. Systematic testing demonstrated that both modern and legacy laser instruments are capable of ablating through plagioclase, pyroxene and fused glass to depths of 200 μm. Modern instruments offer software benefits to identifying optically‐indistinct petrographic features, chemical zoning and avoiding alteration phases by using overlain high‐resolution datasets. Extracting delineated targets of varying geometry was achieved under binocular microscope using common mineral‐separation tools. Analysis of RM glass used as mineral proxies indicate (a) no significant thermal aureole on ablated margins that could affect measured parent‐daughter ratios, (b) no elevated risk of contamination compared with traditional mineral separation techniques, (c) excellent blanks for low‐yield analyses and (d) high‐precision ID‐TIMS results (87Sr/86Sr and 143Nd/144Nd) for sub‐100 ng Sr loads and sub‐10 ng Nd loads. [ABSTRACT FROM AUTHOR]

Aims: Immunosuppressant and kidney function monitoring are crucial for kidney transplant recipient follow‐up. Microsamples enable remote sampling and minimise patient burden as compared to conventional venous sampling at the clinic. We developed a liquid chromatography–tandem mass spectrometry assay to quantify tacrolimus, mycophenolic acid (MPA), creatinine and iohexol in dried blood spot (DBS), and volumetric absorptive microsample (VAMS) samples. Methods: The assay was successfully validated analytically for all analytes. Clinical validation was conducted by direct comparison of paired DBS, VAMS and venous reference samples from 25 kidney transplant recipients. Patients received iohexol 5–15 minutes before immunosuppressant intake and were sampled 0, 1, 2 and 3 hours thereafter, enabling tacrolimus and MPA area under the concentration–time curve (AUC) and creatinine‐based and iohexol‐based glomerular filtration rate (GFR) estimation. Method agreement was evaluated using Passing–Bablok regression, Bland–Altman analysis and the percentages of values within 15–30% of the reference (P15–P30) with a P20 acceptance threshold of 80%. Results: For DBS samples, method agreement was excellent for tacrolimus trough concentrations (n = 25, P15 = 92.0%) and AUCs (n = 25; P20 = 95.8%) and adequate for creatinine‐based GFR trend monitoring (n = 25; P20 = 80%). DBS‐based MPA AUC assessment showed suboptimal agreement (n = 16; P20 = 68.8%), but was considered acceptable given its P30 of 100%. The assay performed inadequately for DBS‐based iohexol GFR determination (n = 24; P20 = 75%). The VAMS technique generally showed inferior performance, but can be considered for certain situations. Conclusion: The assay was successfully validated for tacrolimus, MPA and creatinine quantification in DBS samples, enabling simultaneous remote kidney function trend monitoring and immunosuppressant therapeutic drug monitoring in kidney transplant recipients. [ABSTRACT FROM AUTHOR]

Granulite xenoliths, sourced from the lower cratonic crust and brought to the Earth's surface within volcanic rocks, offer unique insights into the formation and destruction of cratons. Age determinations are essential for constructing the thermal history of cratons. However, accurate dating is complicated by the xenoliths' extended exposure to high temperatures and their complex thermal histories. Specifically, the effects of extended lower crust residency and entrainment heating on coupled Sm–Nd and Lu–Hf systematics remain to be explored. Six xenoliths hosted in the Mesozoic dioritic porphyry from the eastern North China Craton were sampled from center to edge using micro-drilling/sawing techniques. From each xenolith, two to four concentric zones were successfully extracted for coupled Lu–Hf and Sm–Nd geochronological analysis. These xenoliths predominantly exhibit a granoblastic texture, with minerals that are mostly unzoned. Textural and chemical analyses of minerals indicate a decompression process following the granulite-facies metamorphism, with subsequent multiple reheating events. Thermobarometric calculations suggest granulite-facies equilibration at temperatures of ∼750 °C and pressures of 1.2–2.0 GPa. Consistent Lu–Hf and U–Pb ages of ca. 1.7 Ga, obtained from garnet, zircon, and titanite in chemical and textural equilibrium, are attributed to granulite-facies metamorphism. The Paleoproterozoic Lu–Hf ages and the Neoproterozoic Sm–Nd dates are indistinguishable across all concentric zones within each xenolith, whereas Sm–Nd ages are consistently ∼1.0 Ga younger than the corresponding Lu–Hf ages. This discrepancy suggests a complex history for this section of the lower cratonic crust, marked by a granulite-facies metamorphic event around 1.7 Ga, followed by prolonged cooling. A significant heating event during the Tonian, likely due to regional mantle plume activity, is inferred to have partially or completely reset the Sm–Nd isochrons. This thermal event and subsequent thermal relaxation on the samples at different residence depths thereby decoupled the Sm–Nd system from the Lu–Hf system, signifying a thermal pulse at the southern margin of North China Craton. The Mesozoic entrainment heating event appears to have had minimal impact on the Lu–Hf/Sm–Nd systematics of garnet and U–Pb of zircon/titanite. Our data highlight the potential of coupled microsampling Lu–Hf and Sm–Nd geochronology on individual xenoliths to reveal tectonic episodes within the lower crust that might be undetected by accessory mineral U–Pb geochronology. [ABSTRACT FROM AUTHOR]

• An LC-MS/MS method for VAMS was developed for quantifying Lurasidone using a liquid–liquid extraction technique. • The method was validated over a concentration range of 5.0 to 1200.0 ng/mL and achieved acceptable precision and accuracy. • The recovery for analyte from VAMS was approximately 40% at four different concentrations. • A comparative study between both conventional (plasma) and microsampling (DBS and VAMS) techniques. • The study supports the advantages of microsampling while maintaining scientific judgement. The ecological impact of biological, chemical, and analytical research practices, including toxic reagents and biohazardous waste, has led to the development of alternative sampling and extraction techniques for bioanalysis. Microsampling (sample volume < 50 µL) aligns with the 3Rs principle, allowing multiple sampling points from the same animal at different time points and improving animal welfare. A bioanalytical method was developed to investigate factors related to bioanalytical challenges and the implementation of microsampling techniques. An LC-MS/MS method for Volumetric Absorptive Microsampling (VAMS), 20 µL, was developed for quantifying Lurasidone using a liquid–liquid extraction technique. The method uses a C18, Phenomenex column for chromatographic separation and a mobile phase composition of Methanol, Acetonitrile, and Water with 0.1 % HFBA. The method was validated over a concentration range of 5.0 to 1200.0 ng/mL and achieved acceptable precision and accuracy. The recovery for analyte from VAMS was approximately 40% at four different concentrations and is consistent (%CV < 15), with no significant differences among HCT levels. The matrix factor ranged between 85.00 and 115.00 %, showing no substantial issues with reduced or enhanced signal. The stability data showed no significant degradation of LUR in VAMS samples when stored at room temperature for 15 days. The newly established method for Lurasidone confirmed the use of VAMS sampling method and its analysis on LC-MS/MS. Further, the data obtained from microsampling techniques was compared with conventional (plasma) technique, as proof-of-concept, and it confirms the agreement between the two methods. The study supports the advantages of microsampling in protecting the environment and animals while maintaining scientific judgement. [ABSTRACT FROM AUTHOR]

• Volume and hematocrit of blood applied to filter paper collection devices affects test results. • Volume of blood assumed to be in 3.2 mm filter paper sub-punch is incorrect resulting in bias. • Volumetric devices negate these pre-analytical issues, improving precision and accuracy. • Devices integrate easily into the workflow of the routine screening/metabolic laboratory. • Volumetric devices will improve biochemical monitoring of patients with Phenylketonuria. Measurement of dried blood spot (DBS) phenylalanine (Phe) is central to the monitoring of patients with phenylketonuria. However, the volume and hematocrit (Hct) of the blood applied to conventional DBS cards significantly affects analytical results. Volumetric blood collection devices are reported to be more accurate, precise and less prone to Hct effects. Accuracy, imprecision, effect of blood volume and Hct were evaluated for measurement of Phe and tyrosine using three volumetric devices and compared with the conventional PerkinElmer-226 filter-paper collection devices. i.e. conventional DBS cards. Applicability for use in a clinical laboratory was assessed qualitatively. Blood volume did not impact on the performance of the volumetric devices; however, significant biases were observed with the conventional DBS card. A higher Hct introduced unacceptable bias for Neoteryx-Mitra and conventional DBS card. All devices had a mean relative standard deviation (RSD) ≤ 4.1 %, except for the Neoteryx-Mitra (≤ 6.2 %). Relative to liquid blood, the mean biases of Phe for the various devices were −5.1 (HemaXis-DB10), −7.8 (Capitainer-qDBS), −12.0 (Neoteryx-Mitra) and −32.6 % (conventional DBS card). Introducing volumetric collection devices will overcome the significant pre-analytical issues associated with conventional DBS collection and improve the biochemical monitoring of patients with PKU. [ABSTRACT FROM AUTHOR]

Phosphatidylethanols (PEth) are a group of abnormal phospholipids which are formed within the human body in the presence of ethanol. As PEth accumulates in red blood cells, which prolongs its detectability, it became popular as a direct alcohol biomarker. When alcohol is consumed regularly, PEth concentrations in the human blood reach an equilibrium (plateau) between formation and degradation which is representative of drinking habits. A wide range of applications has been demonstrated for PEth, whereby in most studies it could provide advancements regarding accuracy and precision when compared to already established alcohol biomarkers (carbohydrate‐deficient transferrin, gamma‐glutamyltransferase, and ethyl glucuronide). Although PEth has been the focus of many research projects all around the world, the final breakthrough from the research laboratory into the clinical mass market is still ongoing. In this overview article, we discuss the evolution of PEth analysis, its applications, and the associated challenges. The main reasons that hinder the use of PEth in the mass market were identified as (a) the lack of implementing a uniform reference measurement system, which should ensure that every single PEth result is comparable and/or (b) ensuring good laboratory practice dedicated to PEth analysis, which should guarantee that every result obtained by an individual laboratory is correct. These challenges regarding PEth analytics must be carefully addressed in the near future before the implementation of common cut‐off values and international guidelines can take place. This article is categorized under:Toxicology > AlcoholToxicology > Analytical ToxicologyToxicology > Drug Analysis [ABSTRACT FROM AUTHOR]

Therapeutic drug monitoring (TDM) is a specialized area of laboratory medicine which involves the measurement of drug concentrations in biological fluids with the aim of optimizing efficacy and reducing side effects, possibly modifying the drug dose to keep the plasma concentration within the therapeutic range. Plasma and/or whole blood, usually obtained by venipuncture, are the “gold standard” matrices for TDM. Microsampling, commonly used for newborn screening, could also be a convenient alternative to traditional sampling techniques for pharmacokinetics (PK) studies and TDM, helping to overcome practical problems and offering less invasive options to patients. Although technical limitations have hampered the use of microsampling in these fields, innovative techniques such as 3-D dried blood spheroids, volumetric absorptive microsampling (VAMS), dried plasma spots (DPS), and various microfluidic devices (MDS) can now offer reliable alternatives to traditional samples. The application of microsampling in routine clinical pharmacology is also hampered by the need for instrumentation capable of quantifying analytes in small volumes with sufficient sensitivity. The combination of microsampling with high-sensitivity analytical techniques, such as liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), is particularly effective in ensuring high accuracy and sensitivity from very small sample volumes. This manuscript provides a critical review of the currently available microsampling devices for both whole blood and other biological fluids, such as plasma, urine, breast milk, and saliva. The purpose is to provide useful information in the scientific community to laboratory personnel, clinicians, and researchers interested in implementing the use of microsampling in their routine clinical practice.

Microsampling (MS) has been increasingly used in toxicity studies reducing animal use for toxicokinetic analysis. However, especially for drugs with hematotoxic properties, the potential effects of MS on hematological parameters and subsequent toxicity assessment should be considered, while such properties are frequently unknown at the discovery stage. Here, we conducted a rat 2-week study of hematotoxic compounds and evaluated the effects of MS on toxicity assessment. Six-week-old female SD rats were orally dosed with vehicle, methylene blue trihydrate (MB: 300 mg/kg/day), or azathioprine (AZP: 12 and 24 mg/kg/day) for 2 weeks. Each treatment group was divided into non-MS and MS subgroups, and in the MS subgroups, 50 μL/time point of blood was collected from the jugular vein at 7 time points each on Days 1 and 13 of dosing. The test items included clinical signs, body weight, urinalysis, hematology, blood chemistry, necropsy, organ weight, and histopathology. In the MB non-MS subgroup, there were low values in red blood cell parameters, high values in reticulocytes and bilirubin, and increased extramedullary hematopoiesis, reflecting hemolytic anemia. In the AZP non-MS subgroup, there were low values of red and white blood cell parameters and decreased cellularity in the bone marrow, reflecting myelosuppression. The effects of MB and AZP were similarly observed in the MS subgroups, and the effects of MS on the toxicological endpoints were generally small. Based on these results, the effects of MS on toxicity assessment were considered to be small in rat toxicity studies even for hematotoxic compounds. [ABSTRACT FROM AUTHOR]

Microsamples are collections usually less than 50 µL, although all devices that we have captured as part of this review do not fit within this definition (as some can perform collections of up to 600 µL); however, they are considered microsamples that can be self-administered. These microsamples have been introduced in pre-clinical, clinical, and research settings to overcome obstacles in sampling via traditional venepuncture. However, venepuncture remains the sampling gold standard for the metabolic phenotyping of blood. This presents several challenges in metabolic phenotyping workflows: accessibility for individuals in rural and remote areas (due to the need for trained personnel), the unamenable nature to frequent sampling protocols in longitudinal research (for its invasive nature), and sample collection difficulty in the young and elderly. Furthermore, venous sample stability may be compromised when the temperate conditions necessary for cold-chain transport are beyond control. Alternatively, research utilising microsamples extends phenotyping possibilities to inborn errors of metabolism, therapeutic drug monitoring, nutrition, as well as sport and anti-doping. Although the application of microsamples in metabolic phenotyping exists, it is still in its infancy, with whole blood being overwhelmingly the primary biofluid collected through the collection method of dried blood spots. Research into the metabolic phenotyping of microsamples is limited; however, with advances in commercially available microsampling devices, common barriers such as volumetric inaccuracies and the 'haematocrit effect' in dried blood spot microsampling can be overcome. In this review, we provide an overview of the common uses and workflows for microsampling in metabolic phenotyping research. We discuss the advancements in technologies, highlighting key considerations and remaining knowledge gaps for the employment of microsamples in metabolic phenotyping research. This review supports the translation of research from the 'bench to the community'. [ABSTRACT FROM AUTHOR]

Red organic dye identification is an important topic for conservation of Japanese ukiyo-e prints. Of particular interest are the works of Suzuki Harunobu, who was working at the inception of full-color printmaking. These prints were made on thin kōzo paper and woodblock printed with semi-transparent to opaque regions of dye(s) and/or pigment(s) mixed with binder. This study used imaging analysis, X-ray fluorescence (XRF), Raman, and surface-enhanced Raman spectroscopies (SERS) to identify the red dyes and pigments on Harunobu prints in the collection of the Portland Art Museum. Through image analysis (visible, UV, and IR illuminations), 23 prints were categorized by appearance. XRF results provided identification of vermilion and ochre pigments, and identified color fields that contained lead. Raman analysis allowed the identification of red lead, and SERS was used to identify both safflower and madder dyes. This work is expected to contribute to the body of knowledge regarding the red dye and pigment palette and mixtures in use in the mid- to late eighteenth century, in the critical early years of full-color printmaking. [ABSTRACT FROM AUTHOR]

Therapeutic drug monitoring (TDM) of biologics—encompassing the measurement of (trough) concentrations and anti-drug antibodies—is emerging as a valuable tool for clinical decision making. While this strategy needs further validation, attention on its implementation into the clinic is warranted. Rapid testing and easy sampling are key to its implementation. Here, we aimed to evaluate the feasibility and volunteers' perception of home microsampling for quantification of adalimumab (ADM) concentrations in psoriasis patients. In addition, we compared lateral flow testing (LFT) with enzyme-linked immunosorbent assay (ELISA). Patients participating in the SUPRA-A study (clinicaltrials.gov NCT04028713) were asked to participate in a substudy where volumetric absorptive microsampling (VAMS) was performed at home. At three time points, whole blood and corresponding serum samples were collected for ADM measurement using an in-house ELISA. In addition, the patients' perspective on microsampling was evaluated via a questionnaire. LFT-obtained ADM concentrations agreed very well with ELISA results (Pearson's correlation = 0.95 and R2 = 0.89). ADM concentrations determined in both capillary (via finger prick) and corresponding venous blood VAMS samples correlated strongly with serum concentrations (Pearson's correlation = 0.87). Our preliminary data (n = 7) on rapid testing and home-based microsampling are considered promising with regard to TDM implementation for adalimumab, warranting further research. [ABSTRACT FROM AUTHOR]

Clozapine is one of the most widely used second-generation antipsychotic drugs (SGAs) for the treatment of schizophrenia. Despite advantages over first-generation drugs, clozapine still shows significant side effects and interindividual variations in efficacy. In order to ensure frequent therapeutic drug monitoring (TDM) and improve the compliance of psychiatric patients undergoing clozapine treatment, two novel dried microsampling approaches based on whole blood and plasma volumetric absorptive microsampling (b-VAMS and p-VAMS) and microfluidic generated-dried blood spot technology (mfDBS) were developed and coupled to HPLC with electrochemical detection (ED). The proposed miniaturized strategies by means of VAMS and microfluidic channel-based devices provide several advantages in terms of collection, storage, and handling compared to classical blood and plasma processing. Satisfactory validation results were obtained for all microsampling platforms, with mean extraction yields >85.1%, precision as relative standard deviation (RSD) < 5.1%, and stability < 4.5% analyte loss after 30 days for p-VAMS; mean extraction yields > 83.4%, precision RSD < 5.4%, and stability < 4.6% analyte loss after 30 days for b-VAMS, and mean extraction yields > 74.0%, precision RSD < 5.6%, and stability < 4.9% analyte loss after 30 days for mfDBS. The original microsampling methodologies have been successfully applied to the blood and plasma collected from five psychiatric patients for the monitoring of the levels of clozapine and its main metabolites, providing robust and reliable quali-quantitative results. Comparisons between results of the two dried microsampling technologies with those obtained by classic fluid plasma analysis were in good agreement and have demonstrated that the proposed miniaturized approaches could be suitable for TDM purposes. [ABSTRACT FROM AUTHOR]

According to ICH S3A Q&A focusing on microsampling, its application should be avoided in main study animals for test drugs that could exacerbate hematological parameters with frequent blood sampling. However, no study has reported the effects of microsampling on toxicity parameters of drugs known to induce hematological toxicity. Therefore, we assessed the toxicological effects of serial microsampling on rats treated with phenacetin as a model drug. In a common 28-day study, 50 μL of microsampling was performed at 6-time points on days 1 to 2 and 7-time points on days 27 to 28 from the jugular vein of Sprague Dawley rats. The study was performed independently by two organizations. The toxicological influence of microsampling was evaluated on body weight, food consumption, hematology, blood clinical chemistry, urine parameters, organ weights, and tissue pathology. Phenacetin treatments induced significant changes of various hematological parameters (including hemoglobin and reticulocytes), some organ weights (including liver and spleen), and some hematology-related pathological parameters in the liver, spleen and bone marrow. Meanwhile, serial microsampling exhibited minimal influence on the assessed parameters, although 20 parameters showed statistical differences mostly at one organization. The current results support the notion that serial 50 μL microsampling from the jugular vein had minimal impacts on overall toxicological profiles even in rats treated with a drug inducing hematological toxicity, but the potential adverse effect on certain parameters could not be fully excluded. Accordingly, this microsampling technique has possibility to be employed even for non-clinical rat toxicity studies using drugs with potentially hematological toxicity. [ABSTRACT FROM AUTHOR]

Here the relation between digestion of proteins by trypsin covalently bound to paper and trypsin in‐solution is investigated. The trypsin acting on paper is covalently bound. A trypsin concentration of 0.5% (w/v) results in the highest digestion activity of all concentrations tested. Additionally, it can be seen that trypsin on‐paper has retained approx. 50% of its activity. Unlike trypsin in‐solution, the stability of the smart proteolysis samplers was regarded to be stable for at least four months when kept refrigerated. Autolysis was very small for covalently bound trypsin: less than 2% compared to in‐solution trypsin. Proteomic analysis of diluted human serum showed more protein identifications (214) in‐solution digestions than on‐paper digestions (76). Also, higher coverage for the in‐solution digestion was obtained. Those proteins identified after on‐paper digestion with no or few disulfide bonds seem to have more similar sequence coverages compared to those identified after in‐solution digestion. Smart samplers allow the determination of at least 70–75 proteins without performing the overnight digestion. All in all, trypsin covalently bound to paper shows to retain high proteolytic activity and is a stable alternative for conventional digestions. In this way, smart proteolytic samplers show their feasibility in pre‐lab sample preparation. [ABSTRACT FROM AUTHOR]

Hair analysis has been mainly used to document drug use history in abusers, drug-facilitated crime cases, doping control analysis and postmortem toxicology in the fields of forensic toxicology, clinical toxicology, and doping control. Hair analysis has also gained more attention in the last 30 years in China. Relevant technology has been promoted as more research has appeared concerning hair analysis, and consensus has been sought among forensic toxicologists regarding aspects such as hair decontamination treatment, detection of abused substances in hair, segmental hair analysis and interpretation of analytical results. However, there are still some limitations in the estimation of drug intake time and frequency by segmental hair analysis due to the different growth cycles evident within a bundle of hairs, the drug incorporation mechanism and sampling errors. Microsampling and imaging mass spectrometry (IMS) technology based on a single hair may be a good choice to estimate drug intake time more accurately. Analysis of hair root samples may also be used to document acute poisoning in postmortem toxicology, and the analysis of the hair shaft can document long-term use of drugs depending on the length of the hair being evaluated.

Clozapine is one of the most widely used second-generation antipsychotic drugs (SGAs) for the treatment of schizophrenia. Despite advantages over first-generation drugs, clozapine still shows significant side effects and interindividual variations in efficacy. In order to ensure frequent therapeutic drug monitoring (TDM) and improve the compliance of psychiatric patients undergoing clozapine treatment, two novel dried microsampling approaches based on whole blood and plasma volumetric absorptive microsampling (b-VAMS and p-VAMS) and microfluidic generated-dried blood spot technology (mfDBS) were developed and coupled to HPLC with electrochemical detection (ED). The proposed miniaturized strategies by means of VAMS and microfluidic channel-based devices provide several advantages in terms of collection, storage, and handling compared to classical blood and plasma processing. Satisfactory validation results were obtained for all microsampling platforms, with mean extraction yields >85.1%, precision as relative standard deviation (RSD) < 5.1%, and stability < 4.5% analyte loss after 30 days for p-VAMS; mean extraction yields > 83.4%, precision RSD < 5.4%, and stability < 4.6% analyte loss after 30 days for b-VAMS, and mean extraction yields > 74.0%, precision RSD < 5.6%, and stability < 4.9% analyte loss after 30 days for mfDBS. The original microsampling methodologies have been successfully applied to the blood and plasma collected from five psychiatric patients for the monitoring of the levels of clozapine and its main metabolites, providing robust and reliable quali-quantitative results. Comparisons between results of the two dried microsampling technologies with those obtained by classic fluid plasma analysis were in good agreement and have demonstrated that the proposed miniaturized approaches could be suitable for TDM purposes.

Volumetric absorptive microsampling (VAMS) is increasingly proposed as a clinically reliable therapeutic drug monitoring (TDM) sampling methodology. The study aimed to establish the reliability and real-life feasibility of patient self-collected capillary VAMS for TDM of antiseizure medication (ASMs), using plasma ASMs concentrations from venous blood as a reference standard. Nurses collected venous and capillary blood samples using VAMS. Afterward, persons with epilepsy (PWE) performed VAMS sampling by themselves. All samples were analyzed by UHPLC-MS/MS. We performed a cross-validation study, comparing ASMs concentrations obtained by VAMS nurses and patients' self-collected versus plasma through Bland-Altman analysis and Passing-Bablok regression. We enrolled 301 PWE (M: F 42.5%:57.5%; mean age 44±16 years), treated with 13 ASMs, providing a total of 464 measurements. Statistical analysis comparing VAMS self-collected versus plasma ASMs concentrations showed a bias close to zero and slope and intercept values indicating a good agreement for CBZ, LCS, LEV, LTG, OXC, PB, and PHT, while a systematic difference between the two methods was found for VPA, PMP, TPM and ZNS. This is the first study showing the reliability and feasibility of the real-world application of PWE self-collected VAMS for most of the ASMs considered, giving a promising basis for at-home VAMS applications. [Display omitted] • Real-life data on using VAMS for antiseizure medication (ASMs) are lacking. • Cross-validation investigated reliability and feasibility of VAMS vs venous blood. • VAMS showed good accuracy and reliability for CBZ, LCS, LEV, LTG, OXC, PB, and PHT. • Comparison between self and nurse-collected VAMS demonstrates good correlation. • VAMS was demonstrated as a promising tool for future TDM at-home applications. [ABSTRACT FROM AUTHOR]

Microneedles (MNs) have shown a great potential for the microsampling of dermal interstitial fluid (ISF) in a minimally invasive manner for point-of-care testing (POCT). The swelling properties of hydrogel-forming microneedles (MNs) allow for passive extraction of ISF. Surface response approaches, including Box-Behnken design (BBD), central composite design (CCD), and optimal discrete design, were employed for the optimization of hydrogel film by studying the effects of independent variables (i.e., the amount of hyaluronic acid, GantrezTM S-97, and pectin) on the swelling property. The optimal discrete model was selected to predict the appropriate variables, due to the good fit of the experimental data and the model validity. The analysis of variance (ANOVA) of the model demonstrated p-value < 0.0001, R2 = 0.9923, adjusted R2 = 0.9894, and predicted R2 = 0.9831. Finally, the predicted film formulation containing 2.75% w/w hyaluronic acid, 1.321% w/w GantrezTM S-97, and 1.246% w/w pectin was used for further fabrication of MNs (525.4 ± 3.8 µm height and 157.4 ± 2.0 µm base width), which possessed 1508.2 ± 66.2% swelling, with 124.6 ± 7.4 µL of collection volume, and could withstand thumb pressure. Moreover, almost 50% of MNs achieved a skin insertion depth of approx. 400 µm, with 71.8 ± 3.2% to 78.3 ± 2.6% recoveries. The developed MNs show a promising prospect in microsample collection, which would be beneficial for POCT.

Blood microsampling combined with large panels of clinically relevant tests are of major interest for the development of home sampling and predictive medicine. The aim of the study was to demonstrate the practicality and medical utility of microsamples quantification using mass spectrometry (MS) in a clinical setting by comparing two types of microsamples for multiplex MS protein detection. In a clinical trial based on elderly population, we compared 2 µL of plasma to dried blood spot (DBS) with a clinical quantitative multiplex MS approach. The analysis of the microsamples allowed the quantification of 62 proteins with satisfactory analytical performances. A total of 48 proteins were significantly correlated between microsampling plasma and DBS (p < 0.0001). The quantification of 62 blood proteins allowed us to stratify patients according to their pathophysiological status. Apolipoproteins D and E were the best biomarker link to IADL (instrumental activities of daily living) score in microsampling plasma as well as in DBS. It is, thus, possible to detect multiple blood proteins from micro-samples in compliance with clinical requirements and this allows, for example, to monitor the nutritional or inflammatory status of patients. The implementation of this type of analysis opens new perspectives in the field of diagnosis, monitoring and risk assessment for personalized medicine approaches.

Dalbavancin (DBV) is a long-acting antistaphylococcal lypoglycopeptide that is being increasingly used for long-term treatment of a wide range of subacute and/or chronic infections, mainly osteo-articular infections (OAI). Population pharmacokinetic studies showed that two 1500 mg doses 1 week apart can ensure effective treatment for several weeks. In this scenario, therapeutic drug monitoring (TDM) can be a helpful tool for providing clinicians with real-time feedback on the duration of optimal treatment by measuring drug concentrations over time in each single patient. The aim of this study was to develop and validate a fast and simple analytical method based on the Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry (ITD LC-MS/MS) technique for measuring DBV concentrations in human plasma microsamples. It will allow an innovative, very convenient and minimally invasive way of sampling. Analysis was performed by simple single-step sample preparation and very short instrumental run time (4 min). Analytical performance met all criteria in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, dilution integrity and stability under different conditions set by the European Medicines Agency (EMA) for drug quantification by means of bioanalytical methods. The method was successfully applied for measuring DBV concentrations (range = 2.0–77.0 mg/L) in a cohort of patients receiving long-term DBV treatment of subacute and/or chronic infections.

Mercury (Hg) is a global pollutant and a danger to human health. Human biomonitoring of Hg using a dried blood matrix instead of venous blood sampling for exposure assessment is of growing interest. This study aims to develop, validate, and evaluate the application of volumetric absorptive microsampling (VAMS) for Hg biomonitoring in humans. Sampling, drying, and storage conditions were evaluated during method development. Storage in pre-cleaned glass vials after drying for 2 h in a desiccator ensured analyte stability for at least 4 weeks. Sixty-eight paired capillary VAMS and venous blood samples from volunteers in Munich, Germany, were used for method validation. Hg levels in VAMS and venous blood samples were determined by direct mercury analysis. The limits of detection and quantitation for VAMS were 0.18 and 0.61 µg/l, respectively. However, sensitivity could be improved by using two microsamples for analysis instead of one. Hg levels in VAMS samples correlated very well with Hg levels in venous blood samples (R2 = 0.958). Furthermore, VAMS showed a high accuracy (median recovery: 117%) and precision (median relative standard deviation: 8.7%), especially for Hg concentrations above 1.0 µg/l. In fact, accuracy and precision of VAMS improved with increasing Hg concentrations. In conclusion, VAMS in combination with direct mercury analysis is an accurate and viable alternative for human biomonitoring of Hg. [ABSTRACT FROM AUTHOR]

Reducing the volume of blood sampled from neonatal or paediatric patients is important to facilitate research in a group that is under-represented in clinical studies. Not all patients have a cannula available for blood sampling, meaning there are real advantages in obtaining a blood microsample by skin prick. In this study, the results obtained from both capillary microsamples (CMS) and a microfluidic (MF)-CMS by skin prick are compared to conventional plasma sampled from an arterial catheter in a clinical bridging study. Six critically ill patients receiving meropenem were included with the incurred sample reanalysis test meeting the acceptance criteria for both CMS (n = 24 samples) and MF-CMS (n = 20 samples). Bland–Altman plots comparing MF-CMS to conventional arterial blood sampling revealed a difference of − 12.7 ± 22.1% (mean ± standard deviation (SD), and comparing CMS to conventional arterial blood sampling a difference of − 3.4 ± 17.0%. At − 12.7%, the bias between MF-CMS and conventional sampling is greater than the bias found with CMS, although within the limit of acceptability for analytical accuracy (that being ± 15%). Samples collected by skin prick and using CMS produced meropenem concentrations that were comparable to those obtained from conventional arterial catheter sampling. CMS samples were found to be stable when stored in the capillary tube for 24 h at 5 °C or for 4 h at room temperature. [ABSTRACT FROM AUTHOR]

Therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) is not yet performed routinely in the standard care of oncology patients, although it offers a high potential to improve treatment outcome and minimize toxicity. TKIs are perfect candidates for TDM as they show a relatively small therapeutic window, a wide inter-patient variability in pharmacokinetics and a correlation between drug concentration and effect. Moreover, most of the available TKIs are susceptible to various drug-drug interactions and medication adherence can be checked by performing TDM. Plasma, obtained via traditional venous blood sampling, is the standard matrix for TDM of TKIs. However, the use of plasma poses some challenges related to sampling and stability. The use of dried blood microsamples can overcome these limitations. Collection of samples via finger-prick is minimally invasive and considered convenient and simple, enabling sampling by the patients themselves in their home-setting. The collection of small sample volumes is especially relevant for use in pediatric populations or in pharmacokinetic studies. Additionally, working with dried matrices improves compound stability, resulting in convenient and cost-effective transport and storage of the samples. In this review we focus on the different dried blood microsample-based methods that were used for the quantification of TKIs. Despite the many advantages associated with dried blood microsampling, quantitative analyses are also associated with some specific difficulties. Different methodological aspects of microsampling-based methods are discussed and applied to TDM of TKIs. We focus on sample preparation, analytics, internal standards, dilution of samples, external quality controls, dried blood spot specific validation parameters, stability and blood-to-plasma conversion methods. The various impacts of deviating hematocrit values on quantitative results are discussed in a separate section as this is a key issue and undoubtedly the most widely discussed issue in the analysis of dried blood microsamples. Lastly, the applicability and feasibility of performing TDM using microsamples in a real-life home-sampling context is discussed. [ABSTRACT FROM AUTHOR]

Therapeutic drug monitoring (TDM) of tyrosine kinase inhibitors (TKIs) is not yet performed routinely in the standard care of oncology patients, although it offers a high potential to improve treatment outcome and minimize toxicity. TKIs are perfect candidates for TDM as they show a relatively small therapeutic window, a wide inter-patient variability in pharmacokinetics and a correlation between drug concentration and effect. Moreover, most of the available TKIs are susceptible to various drug-drug interactions and medication adherence can be checked by performing TDM. Plasma, obtained via traditional venous blood sampling, is the standard matrix for TDM of TKIs. However, the use of plasma poses some challenges related to sampling and stability. The use of dried blood microsamples can overcome these limitations. Collection of samples via finger-prick is minimally invasive and considered convenient and simple, enabling sampling by the patients themselves in their home-setting. The collection of small sample volumes is especially relevant for use in pediatric populations or in pharmacokinetic studies. Additionally, working with dried matrices improves compound stability, resulting in convenient and cost-effective transport and storage of the samples. In this review we focus on the different dried blood microsample-based methods that were used for the quantification of TKIs. Despite the many advantages associated with dried blood microsampling, quantitative analyses are also associated with some specific difficulties. Different methodological aspects of microsampling-based methods are discussed and applied to TDM of TKIs. We focus on sample preparation, analytics, internal standards, dilution of samples, external quality controls, dried blood spot specific validation parameters, stability and blood-to-plasma conversion methods. The various impacts of deviating hematocrit values on quantitative results are discussed in a separate section as this is a key issue and undoubtedly the most widely discussed issue in the analysis of dried blood microsamples. Lastly, the applicability and feasibility of performing TDM using microsamples in a real-life home-sampling context is discussed.

To enhance the performance of a conventional pulse width modulation (PWM)-based microsampling system, a novel system was developed by bifurcating a fluidic path and by reusing the conventional components. A micro-metering valve was newly equipped to control the speed of the sample introduction, and a reflective optical sensor was used to detect the arrival of a sample. In addition, an analog logic circuit was designed to minimize the response time of the control system. This approach features precise microsampling, rapid response, and stable operation. To verify the volumetric sampling performance and to understand the operational characteristics, a series of experiments were performed. The results show that the aspirated volume was maintained at about 2.8 microliters and that the aspiration requires less than 0.3 seconds. Moreover, the sample removal operation was performed identical to a conventional PWM-based microsampling system. Because our spectrophotometer is operated automatically, the reduction of the sampling time is highly advantageous to measure many samples. Therefore, the total measurement time may be reduced proportional to the number of samples to be analyzed. [ABSTRACT FROM AUTHOR]

Miniaturisation and simplification are novel approaches in clinical bioanalysis, especially in therapeutic drug monitoring (TDM). These contemporary trends are related to the sampling, pre-treatment, and analysis of biological fluids. Currently, dried blood spot (DBS), one of the most popular microsampling techniques, is feasible and inexpensive. However, obtaining reliable results with sample homogeneity and volume variability is difficult. Volumetric Absorptive Microsampling (VAMS) has recently enabled the accurate and precise collection of a fixed blood volume. It reduced the hematocrit effect, improved volumetric accuracy, and generated results correlating with the dose and drug exposure from wet blood. This review focuses on VAMS-Mitra™ devices, which have become increasingly important since 2014, mainly for TDM and toxicology studies. First, the current literature has been reviewed based on immunosuppressants and their determination in samples obtained using Mitra™. Second, the critical points, weaknesses, and strengths have been characterized in contrast to classic venipuncture and other microsampling methods. Finally, we indicate the points of attention according to the perspective of Mitra™ as well as its usefulness in clinical practice. VAMS is currently state-of-the-art in microsampling and seems to be a good instrument for improving adherence to immunosuppressive therapy, especially in the pediatric population.

To prevent doping practices in sports, the World Anti-Doping Agency implemented the Athlete Biological Passport (ABP) program, monitoring biological variables over time to indirectly reveal the effects of doping rather than detect the doping substance or the method itself. In the context of this program, a highly multiplexed mass spectrometry-based proteomics assay for 319 peptides corresponding to 250 proteins was developed, including proteins associated with blood-doping practices. "Baseline" expression profiles of these potential biomarkers in capillary blood (dried blood spots (DBS)) were established using multiple reaction monitoring (MRM). Combining DBS microsampling with highly multiplexed MRM assays is the best-suited technology to enhance the effectiveness of the ABP program, as it represents a cost-effective and robust alternative analytical method with high specificity and selectivity of targets in the attomole range. DBS data were collected from 10 healthy athlete volunteers over a period of 140 days (28 time points per participant). These comprehensive findings provide a personalized targeted blood proteome "fingerprint" showcasing that the targeted proteome is unique to an individual and likely comparable to a DNA fingerprint. The results can serve as a baseline for future studies investigating doping-related perturbations.

Phosphatidylethanol (PEth) is a group of phospholipids formed in cell membranes following alcohol consumption by action of the enzyme phospholipase D (PLD). PEth measurement in whole blood samples is established as a specific alcohol biomarker with clinical and forensic applications. However, in blood specimens containing ethanol, formation of PEth may continue after sampling leading to falsely elevated concentrations. This study evaluated the use of dried blood spot (DBS) and microsampling specimens to avoid post-sampling formation of PEth. Filter paper cards and three commercial devices for volumetric microsampling of finger-pricked blood were assessed, using PEth-negative and PEth-positive whole blood fortified with 2 g/L ethanol. PEth (16:0/18:1) was measured by LC–MS/MS. Post-sampling formation of PEth occurred in wet blood and in the volumetric devices, but not filter paper cards, when stored at room temperature for 48 h. Addition of an inhibitor of PLD, sodium metavanadate (NaVO3), eliminated post-sampling formation during storage and drying. In conclusion, the present study confirmed previous observations that PEth can be formed in blood samples after collection, if the specimen contains ethanol. The results further demonstrated that post-sampling formation of PEth from ethanol also occurred with commercial devices for volumetric dried blood microsampling. In order for a PEth result not to be questioned, it is recommended to use a PLD inhibitor, whether venous blood is collected in a vacutainer tube or finger-pricked blood is obtained using devices for dried blood microsampling. [ABSTRACT FROM AUTHOR]

Epilepsy is one of the most common diseases of the central nervous system globally. To ensure the correct dosage of antiepileptic treatment, it is helpful to check the blood levels of the administered substances regularly. The analysis of the capillary dried blood samples provides a promising and less‐invasive alternative to venous blood collection. Therefore, the aim of the present study was to develop an LC–MS method for the quantification of 22 commonly used drugs in patients with an epileptic syndrome and 5 drug metabolites in one dried blood spot (DBS). The calibration ranges were selected in such a way that the therapeutic reference ranges in serum for the respective substances were completely covered. The analytical validation was successfully performed according to relevant guidelines with a consideration of requirements for DBS analysis. Proof of concept of the developed method was obtained by the analysis of DBSs from 282 authentic leftover ethylenediaminetetraacetic acid blood samples, which were compared with the corresponding serum concentrations. Altogether, the results show a dependency on the blood/plasma (b/p) ratios of the respective analytes so that for drugs with b/p ratios close to one, for example, lacosamide, levetiracetam, brivaracetam, and sertraline, a good accordance was observed. [ABSTRACT FROM AUTHOR]

Hair analysis has been mainly used to document drug use history in abusers, drug-facilitated crime cases, doping control analysis and postmortem toxicology in the fields of forensic toxicology, clinical toxicology, and doping control. Hair analysis has also gained more attention in the last 30 years in China. Relevant technology has been promoted as more research has appeared concerning hair analysis, and consensus has been sought among forensic toxicologists regarding aspects such as hair decontamination treatment, detection of abused substances in hair, segmental hair analysis and interpretation of analytical results. However, there are still some limitations in the estimation of drug intake time and frequency by segmental hair analysis due to the different growth cycles evident within a bundle of hairs, the drug incorporation mechanism and sampling errors. Microsampling and imaging mass spectrometry (IMS) technology based on a single hair may be a good choice to estimate drug intake time more accurately. Analysis of hair root samples may also be used to document acute poisoning in postmortem toxicology, and the analysis of the hair shaft can document long-term use of drugs depending on the length of the hair being evaluated. [ABSTRACT FROM AUTHOR]

Venous blood is a preferred matrix for the determination of total mercury (Hg) in human biomonitoring but has some drawbacks such as the requirement for an uninterrupted cold chain for transport and storage and the need of medical personnel for sample collection. Therefore, we tested and implemented a simpler and less expensive method for measuring Hg in human blood using dried blood spots (DBS). For method development, we investigated the influence of different storage conditions (temperature, storage vessel, time) on DBS samples. For method validation, we compared DBS and venous blood and investigated whether DBS sampling is suitable for measuring Hg in the general population in countries with low Hg exposure such as Germany. Based on our results, we found that pre-cleaned glass tubes were most suitable for storage of DBS samples, as this allowed the samples to remain stable for at least 4 weeks even at high temperatures (40 °C). When comparing venous blood and DBS, a very good correlation (r = 0.95, p < 0.01, Spearman-Rho) and high precision of DBS (mean relative standard deviation 8.2% vs. 7.2% in venous blood samples) were observed. Comparing the recoveries of both matrices in different concentration ranges, the variation of the recoveries decreases with increasing Hg concentration. The mean recoveries also decreased with increasing Hg concentration. Overall, we found comparable results for DBS and venous blood using direct Hg analysis. Furthermore, we demonstrated that DBS are suitable for Hg biomonitoring in the general population in Germany and improved the storage conditions for the DBS. [ABSTRACT FROM AUTHOR]

The outbreak of the new coronavirus disease changed the world upside down. Every day, millions of people were subjected to diagnostic testing for Covid‐19, all over the world. Molecular tests helped in the diagnosis of current infection by detecting the presence of viral genome whereas serological tests helped in detecting the presence of antibody in blood as well as contributed to vaccine development. This testing helped in understanding the immunogenicity, community prevalence, geographical spread and conditions post‐infection. However, with the contagious nature of the virus, biological specimen sampling involved the risk of transmission and spread of infection. Clinic or pathology visit was the most concerning part. Trained personnel and resources was another barrier. In this scenario, microsampling played an important role due to its most important advantage of remote, contactless, small volume and self‐sampling. Minimum requirements for sample storage and ease of shipment added value in this situation. The highly sensitive instruments and validated assay formats assured the accuracy of results and stability of samples. Microsampling techniques are contributing effectively to the Covid‐19 pandemic by reducing the demand for clinical staff in population‐level testing. The validated and established applications supported the use of microsampling in diagnosis, therapeutic drug monitoring, development of treatment or vaccines and clinical trials for Covid‐19. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate the suitability of whole blood microsampling procedures in non-human primate (NHP) to support toxicokinetic assessments of biotherapeutics in non-human primates. Method: A one-month single dose intravenous pharmacokinetic (PK) study was performed in male cynomolgus monkeys with a human IgG1 control monoclonal antibody (mAb) as a surrogate monoclonal antibody biotherapeutic. In this study, both serum samples (conventional sample collection) and microsampling samples were collected. Microsampling samples were collected from two sites on cynomolgus monkey, with each site using two different devices for the whole blood collection. The drug concentrations from all sample types were determined using a quantitative ligand binding assay (LBA). The PK parameters obtained from microsampling samples and serum samples were examined using a standard PK analysis method. The comparability of key PK parameters from both sample types were analyzed statistically. Results: Similar profiles of drug concentrations versus timepoints from all sampling procedures were observed. The correlations of PK concentration data obtained from serum and microsampling samples were ≥ 0.97 using Brand Alman Plot analysis. The key PK parameters obtained from microsampling samples were comparable to those obtained from serum samples (the % differences of mean PK parameters obtained from both sample types were within ±25%). Conclusion: This study confirmed that PK parameters obtained from samples using microsampling were comparable to that of serum samples in cynomolgus monkeys. Therefore, the microsampling procedure described can be used as a substitute for conventional sampling procedure to support PK/TK studies of biotherapeutics in non-clinical product developments. [ABSTRACT FROM AUTHOR]

Serial blood sampling from one animal is useful to understand relationship between pharmacokinetics (PK) and pharmacological or toxicological events in individual animals. To assess its feasibility in mice, two therapeutic antibodies were used to evaluate impacts by different blood sampling methods, sampling sites, and assay platforms on PK. Denosumab and Panitumumab were intravenously administered to mice and only 0.05 mL of blood sample per point was collected from jugular vein or tail vein. Blood samples were collected serially from a mouse or collected by traditional composite sampling from each mouse. Plasma concentrations of the two drugs were assayed by a generic ligand binding assay using Gyrolab or by a generic ultra-performance liquid chromatography with tandem mass spectrometry. The two assay platforms showed acceptable accuracy and precision and gave comparable PK parameters of the drugs, suggesting that both assays were successfully applied to the PK assessments. Comparable results in the PK profiles were noted between serial and composite blood samplings and differences in the two sampling sites did not impact PK. These findings suggest that microsampling combined with generic assays is useful to assess PK profiles of therapeutic antibodies in mice. • A generic assay of therapeutic antibodies in mouse plasma was developed by LC-MS/MS and ELISA. • The assays were validated and their reproducibility was ensured. • Microsampling coupled with the generic assay was applied to a pharmacokinetic study in mice. • Effects of blood sampling sites and assay platforms on pharmacokinetics were evaluated. [ABSTRACT FROM AUTHOR]

Abstract Background The transcriptional regulation that occurs in malaria parasites during the erythrocytic stages of infection can be studied in vivo with rodent malaria parasites propagated in mice. Time-series transcriptome profiling commonly involves the euthanasia of groups of mice at specific time points followed by the extraction of parasite RNA from whole blood samples. Current methodologies for parasite RNA extraction involve several steps and when multiple time points are profiled, these protocols are laborious, time-consuming, and require the euthanization of large cohorts of mice. Results A simplified protocol has been designed for parasite RNA extraction from blood volumes as low as 20 μL (microsamples), serially bled from mice via tail snips and directly lysed with TRIzol reagent. Gene expression data derived from microsampling using RNA-seq were closely matched to those derived from larger volumes of leucocyte-depleted and saponin-treated blood obtained from euthanized mice with high reproducibility between biological replicates. Transcriptome profiling of microsamples taken at different time points during the intra-erythrocytic developmental cycle of the rodent malaria parasite Plasmodium vinckei revealed the transcriptional cascade commonly observed in malaria parasites. Conclusions Microsampling is a quick, robust and cost-efficient approach to sample collection for in vivo time-series transcriptomic studies in rodent malaria parasites.

Microsamples are collections usually less than 50 µL, although all devices that we have captured as part of this review do not fit within this definition (as some can perform collections of up to 600 µL); however, they are considered microsamples that can be self-administered. These microsamples have been introduced in pre-clinical, clinical, and research settings to overcome obstacles in sampling via traditional venepuncture. However, venepuncture remains the sampling gold standard for the metabolic phenotyping of blood. This presents several challenges in metabolic phenotyping workflows: accessibility for individuals in rural and remote areas (due to the need for trained personnel), the unamenable nature to frequent sampling protocols in longitudinal research (for its invasive nature), and sample collection difficulty in the young and elderly. Furthermore, venous sample stability may be compromised when the temperate conditions necessary for cold-chain transport are beyond control. Alternatively, research utilising microsamples extends phenotyping possibilities to inborn errors of metabolism, therapeutic drug monitoring, nutrition, as well as sport and anti-doping. Although the application of microsamples in metabolic phenotyping exists, it is still in its infancy, with whole blood being overwhelmingly the primary biofluid collected through the collection method of dried blood spots. Research into the metabolic phenotyping of microsamples is limited; however, with advances in commercially available microsampling devices, common barriers such as volumetric inaccuracies and the ‘haematocrit effect’ in dried blood spot microsampling can be overcome. In this review, we provide an overview of the common uses and workflows for microsampling in metabolic phenotyping research. We discuss the advancements in technologies, highlighting key considerations and remaining knowledge gaps for the employment of microsamples in metabolic phenotyping research. This review supports the translation of research from the ‘bench to the community’.

This article evaluates age of weaning and early childhood diets of eight males and nine females from a Middle Holocene (4300-3000 BP) site in Central California, CA-CCO-548. All individuals died as adults. δ(15) N values from serial sections of dentin collagen in first molars suggest females were fully weaned, on average, by 3.6 years of age, about 0.4 years later than males in the sample, suggesting possible greater parental investment in female offspring. However, throughout childhood females consumed lower trophic-level foods than males. This could indicate greater investment in males through provisioning of higher quality foods, or alternatively, some degree of independent foraging by males starting as early as 2 to 3 years of age. Even as adults, these same males and females consumed a different range of foods as indicated by their bone collagen δ(13) C and δ(15) N values. Overall, the data suggest children were enculturated early into their respective gendered diets, with girls consuming greater amounts of plant foods and boys consuming greater amounts of higher-trophic level fish and meat protein.

Purpose: The aim of this study was to develop a useful antibody PK evaluation tool using a combination of cassette-dosing and microsampling in mice and monkeys in order to reduce the number of animals used. Methods: Cetuximab, denosumab, infliximab, and a mixture of the three antibodies, i.e., cassette-dosing, were administered intravenously to cynomolgus monkeys, C57BL/6J mice, and homozygous human neonatal Fc-receptor transgenic (Tg32) mice. Mouse blood was collected from one animal continuously via the jugular vein at nine points. Results: In cynomolgus monkeys, infliximab showed faster elimination in the cassette-dosing group than in the single-dose group. Anti-drug antibody production was observed, but the PK parameters of the clearance and distribution volume were similar in both groups. In C57BL/6J and Tg32 mice, each of the plasma concentrations–time profiles after cassette-dosing were similar to those after single dosing. PK evaluation using a combination of cassette-dosing and microsampling in mice may reduce the number of mice used by approximately 90% compared with the conventional method. Conclusions: The combination of antibody cassette-dosing and microsampling is a promising PK evaluation method as a high-throughput and reliable with reduced numbers of mice and cynomolgus monkeys. [ABSTRACT FROM AUTHOR]

Volumetric absorptive microsampling (VAMS), an emerging microsampling technique, is expected to overcome some disadvantages of dried blood spots such as volume inaccuracy and influence of hematocrit (HT). This study aimed to develop and evaluate a VAMS-based strategy for quantification of 13 frequently prescribed antipsychotics in finger prick blood within the scope of adherence monitoring to complement already-established qualitative urine analysis. The final workflow consisted of VAMS tip hydration and subsequent precipitation. Samples were analyzed by using reversed-phase ultra-high-performance liquid chromatography and Orbitrap mass spectrometry operated in parallel reaction monitoring mode. The analytical procedure was successfully validated based on international recommendations at three different HT values (20%, 40%, 60%) for most of the analytes. Selectivity and within/between-run accuracy and precision were in accordance with the recommendations in most cases. Internal standard–normalized matrix factor met recommended criteria for all analytes at HT 40%. For the HT values of 20% and 60%, only four substances did not meet the criteria. Dilution integrity was given for all substances, except for olanzapine, allowing a quantification over the whole therapeutic range of selected antipsychotics. Long-term stability in VAMS tips was tested and revealed degradation of five antipsychotic drugs after 1 week of storage at 24 °C. A proof of concept of the applicability of the method was obtained by quantification of a selection of the 13 antipsychotic drugs in VAMS tips and matched plasma samples. Results were coherent between matrices. Thus, VAMS was shown to be a promising alternative for adherence monitoring of at least the investigated antipsychotics. [ABSTRACT FROM AUTHOR]

Phosphatidylethanol (PEth) measurement in whole blood samples is established as a specific alcohol biomarker with clinical and forensic applications. Establishment of dried blood spots (DBSs) as a specimen for PEth determination offers several advantages and was the focus of this work. A liquid chromatography tandem mass spectrometry method using a 96-well format for sample preparation was developed and validated. PEth was extracted from DBSs by using isopropanol containing PEth-d5 as internal standard. The blood sampling used a commercial volumetric DBS device having a phosholipase D inhibitor incorporated to stop continuous PEth formation. The method quantified PEth in the range of 0.05-10 μmol/L, with a bias and imprecision of less than 15%. In a clinical study (n = 25) using fingerprick blood, the volumetric device offered more precise quantifications (CV 4.6%) compared with the Whatman 903 Protein Saver card device (CV 16.6%). In another clinical study (n = 48), the use of dried venous and capillary blood, and liquid venous blood was compared under real-life conditions with samples sent by postal service. The capillary and venous DBS samples gave identical results while the liquid blood gave slightly higher values. Calculation of elimination half-life (PEth 16:0/18:1) in 31 cases based on two consecutive samples with 2-9 days in between gave results (mean 6.2 days) that agree with literature but several cases with values over 10 days. In conclusion, this study demonstrates that volumetric DBS is a valid specimen for determination of PEth blood concentrations, offering several advantages., (© 2024 The Authors. Drug Testing and Analysis published by John Wiley & Sons Ltd.)

Background: Kidney disease is fairly unique due to the lack of symptoms associated with disease activity, and it is therefore dependent on biological monitoring. Dried biofluids, particularly dried capillary blood spots, are an accessible, easy-to-use technology that have seen increased utility in basic science research over the past decade. However, their use is yet to reach the kidney patient population clinically or in large-scale discovery science initiatives. The aim of this study was to systematically evaluate the existing literature surrounding the use of dried biofluids in kidney research., Methods: A systematic literature review was conducted using three search engines and a predefined search term strategy. Results were summarised according to the collection method, type of biofluid, application to kidney disease, cost, sample stability and patient acceptability., Results: In total, 404 studies were identified and 67 were eligible. In total, 34,739 patients were recruited to these studies with a skew towards male participants (> 73%). The majority of samples were blood, which was used either for monitoring anti-rejection immunosuppressive drug concentrations or for kidney function. Dried biofluids offered significant cost savings to the patient and healthcare service. The majority of patients preferred home microsampling when compared to conventional monitoring., Conclusion: There is an unmet need in bringing dried microsampling technology to advance kidney disease despite its advantages. This technology provides an opportunity to upscale patient recruitment and longitudinal sampling, enhance vein preservation and overcome participation bias in research., (© 2024 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

To assess the influences of blood sampling volumes or sites on toxicological and tox- icokinetic (TK) evaluations, 4-week duration animal studies and a single-dose TK study of imipramine were conducted. In the toxicological evaluation, six-week-old Sprague-Dawley rats were divided into no blood and blood sampling groups. Fifty microliters (microsampling) or 100 µL (larger sampling) of blood/time point was collected from the jugular vein (50 μL of data was reported previously as Yokoyama et al., 2020) or the tail vein 6 to 7 times on days 1/2 and in week 4. Although no parameters were affected by the 100 µL sample from the tail vein, the 100 µL jugular vein sampling decreased the red blood cell parameters in females, possibly due to hemorrhage at the sampling site. Regarding the TK assessment, 50 µL of blood/site/time point was collected at 6 time points from the tail and jugular vein of the same male rats after single oral administration of 10 or 100 mg/kg imipramine, which was selected as a representative drug with high distribution volume. Although there were no differences in the AUC0-24hr and Cmax values between the sites, the plasma concentrations at the early time points were significantly lower from the tail vein than the jugular vein. From our studies, 50 µL of jugular and tail vein microsampling did not affect the toxicity parameters or AUC/Cmax. However, appropriate toxicity considerations and/or selection of the blood sampling site may be important in the case of larger sampling volumes or blood concentration assessment. [ABSTRACT FROM AUTHOR]

Objectives: Monitoring tacrolimus blood concentrations is important for preventing allograft rejection in transplant patients. Our hospital offers dried blood spot (DBS) sampling, giving patients the opportunity to sample a drop of blood from a fingerprick at home, which can be sent to the laboratory by mail. In this study, both a volumetric absorptive microsampling (VAMS) device and DBS sampling were compared to venous whole blood (WB) sampling. Methods: A total of 130 matched fingerprick VAMS, fingerprick DBS and venous WB samples were obtained from 107 different kidney transplant patients by trained phlebotomists for method comparison using Passing-Bablok regression. Bias was assessed using Bland-Altman. A multidisciplinary team pre-defined an acceptance limit requiring >80% of all matched samples within 15% of the mean of both samples. Sampling quality was evaluated for both VAMS and DBS samples. Results: 32.3% of the VAMS samples and 6.2% of the DBS samples were of insufficient quality, leading to 88 matched samples fit for analysis. Passing-Bablok regression showed a significant difference between VAMS and WB, with a slope of 0.88 (95% CI 0.81–0.97) but not for DBS (slope 1.00; 95% CI 0.95–1.04). Both VAMS (after correction for the slope) and DBS showed no significant bias in Bland-Altman analysis. For VAMS and DBS, the acceptance limit was met for 83.0% and 96.6% of the samples, respectively. Conclusions: VAMS sampling can replace WB sampling for tacrolimus trough concentration monitoring, but VAMS sampling is currently inferior to DBS sampling, both regarding sample quality and agreement with WB tacrolimus concentrations. [ABSTRACT FROM AUTHOR]

In the current study, two groups of rats (five per group) were administered a single oral dose of 500 mg/kg acetaminophen. For toxicokinetic assessment, the Group 1 animals were bled via conventional sparse (two animals/time point) sublingual vein bleeding (~0.5 ml) with anesthesia, while the Group 2 animals were bled via serial tail vein microsampling (~0.075 ml) without anesthesia. All collected blood was processed for plasma. Each Group 2 plasma sample (~30 μl) was divided into 'wet' and 'dried' (dried plasma spots). All plasma samples were analyzed by LC–MS/MS for acetaminophen and its major metabolites acetaminophen glucuronide and acetaminophen sulfate. In addition, plasma and urine samples were collected for analysis of corticosterone and creatinine to assess stress levels. Comparable plasma exposure to acetaminophen and its two metabolites was observed in the plasma obtained via conventional sparse sublingual vein bleeding and serial tail vein microsampling and between the 'wet' and 'dried' plasma obtained by the latter. Furthermore, comparable corticosterone levels or corticosterone/creatinine ratios between the two groups suggested that serial microsampling without anesthesia did not increase the levels of stress as compared with conventional sampling with anesthesia, confirming the utility of microsampling for plasma or dried plasma spots in rodent toxicokinetic assessment. [ABSTRACT FROM AUTHOR]

Intratooth stable isotope profiles in enamel provide time series of dietary and environmental information that if correctly interpreted, serve as archives of seasonal variability in past environments. A major challenge in interpreting these profiles arises from time averaging imparted by enamel mineralization and developmental geometry, whereby the primary (δ13C or δ18O) input signal is attenuated and shifted, which can potentially lead to incorrect interpretations of the magnitude or frequency of seasonal variability. Several forward and inverse models have been developed to reconstruct the primary input signal from intratooth profiles in continuously growing teeth. Here the models developed by Passey and Cerling (2002) and Passey et al. (2005) are extended to molars of Elephantinae, which grow over a long but finite interval of time. Proboscidean molars are particularly attractive for intratooth profiles because they may contain a decade or more of information and they are often well preserved in the fossil record because of their thick enamel and large size. Forward model parameters are established using histological analysis of molar thin sections of extant African elephants (Loxodonta africana) and a mammoth (Mammuthus columbi) and by micro-CT analysis of L. africana molar plates. The density of immature enamel is about 65% of the final density of mature enamel. The appositional length varies from approximately 35 to 55 mm, and the maturation length is about 70 mm. Histological methods are used to determine crown formation time (CFT) in elephant and mammoth molar plates. CFT for the elephant and mammoth molar plates studied in thin section are about 5–6 years and 11 years, which translate to mean growth rates of about 21 mm/year and 16 mm/year, respectively. Coeval molar and tusk profiles from a zoo elephant are compared. The tusk isotope profile serves as a proxy for the primary input signal, and thus provides an opportunity to evaluate the forward and inverse models. The results from the zoo elephant profiles demonstrate that the inverse model accurately reconstructs the amplitude and overall structure of the primary input signal. Inverse model results of mammoth molar profiles show double the range of δ13C in measured enamel profiles. Inversion model results illustrate that improved reconstruction of the primary input signal can lead to more accurate interpretations of the seasonal variability of diet and body water and by extension, vegetation and precipitation in past environments. [ABSTRACT FROM AUTHOR]

Recent advancements in the sensitivity of chemical instrumentation have led to increased interest in the use of microsamples for translational and biomedical research. Paper substrates are by far the most widely used media for biofluid collection, and mass spectrometry is the preferred method of analysis of the resultant dried blood spot (DBS) samples. Although there have been a variety of review papers published on DBS, there has been no attempt to unify the century old DBS methodology with modern applications utilizing modified paper and paper‐based microfluidics for sampling, storage, processing, and analysis. This critical review will discuss how mass spectrometry has expanded the utility of paper substrates from sample collection and storage, to direct complex mixture analysis to on‐surface reaction monitoring. [ABSTRACT FROM AUTHOR]

Due to finalization of the ICH S3A Q&A focusing on microsampling, application of microsampling technique to regular non-clinical animal studies is expected for non-clinical safety assessment of pharmaceuticals. In Europe, microsampling from the tail vein or saphenous vein has often been used, whereas sampling from the jugular vein is thought to be more common for non-clinical studies in Japan. Therefore, we assessed the toxicological effects of serial microsampling from the jugular vein of SD rats in a common 28-day study at 4 independent organizations. Fifty microliter sampling was performed at 6 timepoints on day 1 to 2 and 7 timepoints on day 27 to 28 and its toxicological influences on body weight, food consumption, hematological and clinical chemistry parameters, and organ weights (on day 29 for 3 and day 28 for 1 organizations) were evaluated. The serial microsampling was shown to have no or minimal influences on the assessed parameters. The observed statistical differences for the 18 parameters were sporadic and did not appear to be systemically associated with microsampling. However, the sporadic changes were more often observed in females (14/18 parameters) than in males (6/18), suggesting the possibility that female rats were more susceptible to treatment-based influences. The current results indicate that serial 50 µL sampling from the jugular vein of SD rats had no or very slight toxicological effects, suggesting that this microsampling condition is applicable for toxicokinetic evaluation of non-clinical rat toxicity studies. [ABSTRACT FROM AUTHOR]

Background: Monitoring of immunosuppressive drugs such as everolimus and sirolimus is important in allograft rejection prevention in transplant patients. Dried blood spots (DBS) sampling gives patients the opportunity to sample a drop of blood from a fingerprick at home, which can be sent to the laboratory by mail. Methods: A total of 39 sirolimus and 44 everolimus paired fingerprick DBS and whole blood (WB) samples were obtained from 60 adult transplant patients for method comparison using Passing-Bablok regression. Bias was assessed using Bland-Altman. Two validation limits were pre-defined: limits of analytical acceptance were set at >67% of all paired samples within 20% of the mean of both samples and limits of clinical relevance were set in a multidisciplinary team at >80% of all paired samples within 15% of the mean of both samples. Results: For both sirolimus and everolimus, Passing-Bablok regression showed no differences between WB and DBS with slopes of 0.86 (95% CI slope, 0.72–1.02) and 0.96 (95% CI 0.84–1.06), respectively. Only everolimus showed a significant constant bias of 4%. For both sirolimus and everolimus, limits of analytical acceptance were met (76.9% and 81.8%, respectively), but limits or clinical relevance were not met (77.3% and 61.5%, respectively). Conclusions: Because pre-defined limits of clinical relevance were not met, this DBS sampling method for sirolimus and everolimus cannot replace WB sampling in our center at this time. However, if the clinical setting is compatible with less strict limits for clinical relevance, this DBS method is suitable for clinical application. [ABSTRACT FROM AUTHOR]