Scanning efficacy of p-Chips implanted in the wing and leg of the Big Brown Bat (Eptesicus fuscus).

Individual marking techniques are critical for studying animals, especially in the wild. Current marking methods for bats (Order Chiroptera) have practical limitations and some can cause morbidity. We tested the p-Chip (p-Chip Corp.)-a miniaturized, laser light-activated microtransponder-as a prospective marking technique in a captive research colony of Big Brown Bats (Eptesicus fuscus). We assessed long-term readability and postimplantation effects of p-Chips injected subcutaneously above the second metacarpal (wing; n = 30) and the tibia (leg; n = 13 in both locations). Following implantation (Day 0), p-Chips were scanned with a hand-held ID reader (wand) on postimplantation days (PIDs) 1, 8, 15, 22, 32, 60, 74, 81, 88, 95, and over 1 year later (PID 464). For each trial, we recorded: (1) animal handling time; (2) scan time; (3) number of wand flashes; (4) p-Chip visibility; and (5) overall condition of the bat. Average scan times for p-Chips implanted in both the wing and leg increased over the duration of the study; however, the number of wand flashes decreased, suggesting that efficacy of p-Chip recording increased with user experience. Importantly, over 464 days both the visibility and readability of p-Chips in the wing remained high and superior to tags in the leg, establishing the second metacarpal as the preferred implantation site. Observed morbidity and mortality in captive bats with p-Chips was similar to baseline values for bats without these tags. Because scan efficiency on PID 464 was comparable with earlier days, this indicates that p-Chips implanted in the wing may be suitable as a long-term marking method. Our provisional results suggest that p-Chips are viable for extended field testing to see if they are suitable as an effective alternative to traditional methods to mark bats.

Las técnicas de marcaje individual son fundamentales para el estudio de los animales, especialmente en la naturaleza. Los métodos actuales de marcaje de murciélagos (Chiroptera) tienen limitaciones prácticas y algunos pueden causar morbilidad. Probamos el p-Chip (p-Chip Corp.)­un microtranspondedor miniaturizado activado por luz láser­como técnica de marcaje prospectivo en una colonia en cautiverio de murciélagos morenos (Eptesicus fuscus). Se evaluó la legibilidad a largo plazo y los efectos pos-implantación de los p-Chips inyectados subcutáneamente sobre el segundo metacarpiano (ala; n = 30) y la tibia (pata; n = 13 en ambas localizaciones). Tras la implantación (día 0), se escanearon los p-Chips con un lector de identificación manual (vara) en los días posteriores a la inyección (PID) 1, 8, 15, 22, 32, 60, 74, 81, 88, 95, y más de un año después (PID 464). En cada ensayo se registró: (1) el tiempo total de manipulación del animal; (2) el tiempo de exploración; (3) el número de destellos de proximidad del lector; (4) la visibilidad del p-Chip; y (5) el estado general del murciélago. Los promedios del tiempo de escaneado de los p-Chips implantados tanto en el ala como en la pata aumentaron a lo largo del estudio; sin embargo, el número de destellos del lector disminuyó, lo que sugiere que la eficacia del registro del p-Chip aumentó con la experiencia del usuario. A lo largo de 464 días, tanto la visibilidad como la legibilidad de los p-Chips en el ala siguieron siendo altas y superiores a las de las etiquetas en la pata, lo que estableció el segundo metacarpiano como el lugar preferido de implantación. La morbilidad y mortalidad observadas en murciélagos en cautiverio con p-Chips fue similar a los valores de referencia de los murciélagos sin estas marcas. Dado que la eficacia del escaneado en el PID 464 fue comparable a la de días anteriores, es probable que los p-Chips implantados en el ala sean adecuados como método de marcado a largo plazo. Nuestros resultados provisionales sugieren que los p-Chips son viables para pruebas de campo prolongadas como alternativa prospectiva a los métodos tradicionales de marcaje de murciélagos.

The time course of stimulus-specific perceptual learning.

Practice on perceptual tasks can lead to long-lasting, stimulus-specific improvements. Rapid stimulus-specific learning, assessed 24 hours after practice, has been found with just 105 practice trials in a face identification task. However, a much longer time course for stimulus-specific learning has been found in other tasks. Here, we examined 1) whether rapid stimulus-specific learning occurs for unfamiliar, non-face stimuli in a texture identification task; 2) the effects of varying practice across a range from just 21 trials up to 840 trials; and 3) if rapid, stimulus-specific learning persists over a 1-week, as well as a 1-day, interval. Observers performed a texture identification task in two sessions separated by one day (Experiment 1) or 1 week (Experiment 2). Observers received varying amounts of practice (21, 63, 105, or 840 training trials) in session 1 and completed 840 trials in session 2. In session 2, one-half of the observers in each group performed the task with the same textures as in session 1, and one-half switched to novel textures (same vs. novel conditions). In both experiments we found that stimulus-specific learning - defined as the difference in response accuracy in the same and novel conditions - increased as a linear function of the log number of session 1 training trials and was statistically significant after approximately 100 training trials. The effects of stimulus novelty did not differ across experiments. These results support the idea that stimulus-specific learning in our task arises gradually and continuously through practice, perhaps concurrently with general learning.

Contribution of internal noise and calculation efficiency to face discrimination deficits in older adults.

Classification images (CIs) measured in a face discrimination task differ significantly between older and younger observers. These age differences are consistent with the hypothesis that older adults sample diagnostic face information less efficiently, or have higher levels of internal noise, compared to younger adults. The current experiments assessed the relative contributions of efficiency and internal noise to age differences in face discrimination using the external noise masking and double-pass response consistency paradigms. Experiment 1 measured discrimination thresholds for faces embedded in several levels of static white noise, and the resulting threshold-vs.-noise curves were used to estimate calculation efficiency and equivalent input noise: older observers had lower efficiency and higher equivalent input noise than younger observers. Experiment 2 presented observers with two identical sequences of faces embedded in static white noise to measure the association between response accuracy and response consistency and estimate the internal:external (i/e) noise ratio for each observer. We found that i/e noise ratios did not differ significantly between groups. These results suggest that age differences in face discrimination are due to differences in calculation efficiency and additive internal noise, but not to age differences in multiplicative internal noise.

Peripheral target detection can be modulated by target distance but not attended distance in 3D space simulated by monocular depth cues.

Most studies of visuo-spatial attention present stimuli on a 2D plane, and less is known about how attention varies in 3D space. Previous studies found better peripheral detection performance for targets at a near compared to a far depth, simulated by pictorial cues and optical flow. The current study examined whether target detectability is monotonically related to distance along the depth axis, and whether the attended distance modulates the effect of target distance. We investigated these questions in two experiments that measured how apparent distance and target eccentricity affects peripheral target detection when performed alone during passive simulated self-motion, or during a simultaneous, active central car-following task. Experiment 1 found that targets at an apparent distance of 18.5 virtual meters were detected faster and more accurately than targets at 9.25 and 37 virtual meters, and detectability declined with eccentricity. Experiment 2 examined the effect of the attended location by varying the distance between the viewer and the lead car on which participants were instructed to fixate (i.e. the headway) while equating target distances across headway conditions. Experiment 2 replicated the effects found in Experiment 1, and headway did not modulate the effect of target distance. These results are consistent with the hypothesis that target detection depends non-monotonically on the distance between the viewer and the target, and is not affected by the distance between the target and attended location. However, target detection may also have been affected by stimulus characteristics that co-varied with apparent depth, rather than depth per se.

Cannabis use is associated with sexually dimorphic changes in executive control of visuospatial decision-making.

When the outcome of a choice is less favorable than expected, humans and animals typically shift to an alternate choice option on subsequent trials. Several lines of evidence indicate that this "lose-shift" responding is an innate sensorimotor response strategy that is normally suppressed by executive function. Therefore, the lose-shift response provides a covert gauge of cognitive control over choice mechanisms. We report here that the spatial position, rather than visual features, of choice targets drives the lose-shift effect. Furthermore, the ability to inhibit lose-shift responding to gain reward is different among male and female habitual cannabis users. Increased self-reported cannabis use was concordant with suppressed response flexibility and an increased tendency to lose-shift in women, which reduced performance in a choice task in which random responding is the optimal strategy. On the other hand, increased cannabis use in men was concordant with reduced reliance on spatial cues during decision-making, and had no impact on the number of correct responses. These data (63,600 trials from 106 participants) provide strong evidence that spatial-motor processing is an important component of economic decision-making, and that its governance by executive systems is different in men and women who use cannabis frequently.

Biological Matrix Supply Chain Shortages: More Matrices Are Now Rare-the Case for Surrogate Matrices.

The COVID-19 pandemic has strained the biological matrix supply chain. An upsurge in demand driven by numerous COVID-19 therapeutic and vaccine development programs to combat the pandemic, along with logistical challenges sourcing and transporting matrix, has led to increased lead times for multiple matrices. Biological matrix shortages can potentially cause significant delays in drug development programs across the pharmaceutical and biotechnology industry. Given the current circumstances, discussion is warranted around what will likely be increased use of surrogate matrices in support of pharmacokinetic (PK), immunogenicity, and biomarker assays for regulatory filings. Regulatory authorities permit the use of surrogate matrix in bioanalytical methods in instances where matrix is rare or difficult to obtain, as long as the surrogate is appropriately selected and scientifically justified. Herein, the scientific justification and possible regulatory implications of employing surrogate matrix in PK, immunogenicity, and biomarker assays are discussed. In addition, the unique challenges that cell and gene therapy (C>) and other innovative therapeutic modalities place on matrix supply chains are outlined. Matrix suppliers and contract research organizations (CROs) are actively implementing mitigation strategies to alleviate the current strain on the matrix supply chain and better prepare the industry for any future unexpected strains. To maintain ethical standards, these mitigation strategies include projecting matrix needs with suppliers at least 6 months in advance and writing or updating study protocols to allow for additional matrix draws from study subjects and/or re-purposing of subject matrix from one drug development program to another.

Flow cytometry and pharmacokinetics.

Multiparametric flow cytometry is a powerful cellular analysis tool used in various stages of drug development. In adoptive cell therapies, the flow cytometry methods are used for the evaluation of advanced cellular products during manufacturing and to monitor cellular kinetics after infusion. In this report, we discussed the bioanalytical method development challenges to monitor cellular kinetics in CAR-T cell therapies. These method development challenges include procuring positive control samples for the development of the method, flow cytometry panel design, LLOQ, prestain sample stability, staining reagents and data analysis.

The effect of apparent distance on peripheral target detection.

Previous research suggests that peripheral target detection is modulated by viewing distance and distance simulated by pictorial cues and optic flow. In the latter case, it is unclear what cues contribute to the effect of distance. The current study evaluated the effect of distance on peripheral detection in a virtual three-dimensional environment. Experiments 1-3 used a continuous, dynamic central task that simulated observers traveling either actively or passively through a virtual environment following a car. Peripheral targets were flashed on checkerboard-covered walls to the left and right of the path of motion, at a near and a far distance from the observer. The retinal characteristics of the targets were identical across distances. Experiment 1 found more accurate and faster detection for near targets compared to far targets, especially for larger eccentricities. Experiment 2 equated the predictability of target onset across distances and found the near advantage for larger eccentricities in accuracy but a much smaller effect in reaction time (RT). Experiment 3 removed the checkerboard background implemented in Experiments 1 and 2, and Experiment 4 manipulated several static, monocular cues. Experiments 3 and 4 found that the variation in the density of the checkerboard backgrounds could explain the main effect of distance on accuracy but could not completely account for the interaction between target distance and eccentricity. These results suggest that attention is modulated by target distance, but the effect is small. Finally, there were consistent divided attention costs in the central car-following task but not the peripheral detection task.

Critical reagents in flow cytometry, instrumentation and application in drug discovery development.

Flow cytometer is a powerful cellular analysis tool consists of three main components; fluidics, optics and electronics. Flow cytometry methods have been used in all stages of drug development as like ligand binding assays (LBA). Both LBA and flow cytometry methods require specific interaction between the critical reagents and the analytes. Antibodies and their conjugates, viable dyes and permeabilizing buffer are the main critical reagents in flow cytometry methods. Similarly, antibodies, engineered proteins and their conjugates are the main critical reagents in LBA. The main difference between the two methods is the lack of true reference standards for flow cytometry cellular analysis.

First report of Armillaria cepistipes causing root disease on Populus trichocarpa (black cottonwood) in Oregon, USA.

Populus trichocarpa Torr. and Gray (black cottonwood) is an economically and ecologically important tree species native to western North America. It serves as a model tree species in biology and genetics due to its relatively small genome size, rapid growth, and early reproductive maturity (Jansson and Douglas 2007). Black cottonwood is susceptible to root rot caused by at least one species of Armillaria (Raabe 1962), a globally distributed genus that exhibits diverse ecological behaviors (Klopfenstein et al. 2017) and infects numerous woody plant species (Raabe 1962). However, several Armillaria spp. have been isolated from Populus spp. in North America (Mallet 1990), and the most recent report of Armillaria on P. trichocarpa used the now ambiguated name A. mellea (Vahl.) Quel. (see Raabe 1962). In April 2016, mycelial fans and rhizomorphs of an unknown Armillaria species (isolate WV-ARR-3) were collected from P. trichocarpa in a riparian hardwood stand ca. 5.5 km east of Springfield, Oregon, USA (44°3'21.133"N, 122°49'39.935"W). The host was dominant in the canopy, large in diameter (ca. 90-cm dbh) relative to neighboring trees, and exhibited minimal crown dieback (ca. < 5%). A mycelial fan was observed destroying living cambium beneath the inner bark, indicating pathogenicity. The isolate was cultured on malt extract medium (3% malt extract, 3% dextrose, 1% peptone, and 1.5 % agar) and identified as A.cepistipes on the basis of somatic pairing tests and translation elongation factor 1α (tef1) sequences (GenBank Accession No. MK172784). DNA extraction, PCR, and tef1 sequencing followed protocols of Elías-Román et al. (2018). From nine replications of somatic incompatibility tests (18 tester isolates representing six North American Armillaria spp.), the isolate showed high intraspecific compatibility (colorless antagonism) with three A. cepistipes tester isolates (78%), but low compatibility with the other Armillaria spp. (0 - 33%) that occur in the region. Isolate WV-ARR-3 yielded tef1 sequences with a 99% identity to A. cepistipes (GenBank Accession Nos. JF313115 and JF313121). A second isolate (WV-ARR-1; GenBank Accession No. MK172783) with a nearly identical sequence was collected from a maturing P. trichocarpa in a riparian stand ca. 8 km northeast of Monroe, Oregon (44°21'47.57"N, 123°13'14.415"W) along the Willamette River, downstream from the McKenzie river tributary where WV-ARR-3 was collected. Armillaria cepistipes has been reported on Alnus rubra (red alder) in Washington, USA (Banik et al. 1996) and on broad-leaved trees in British Columbia, Canada (Allen et al. 1996). It is generally considered to be a weak pathogen on broad-leaved trees in the Pacific Northwest, but it is also associated with pathogenicity on both coniferous and deciduous trees in Europe (e.g., Lygis et al. 2005). However, a recent phylogenetic study suggested that North American A. cepistipes is phylogenetically distinct from Eurasian A. cepistipes (Klopfenstein et al. 2017), butadditional studies are needed to determine the formal taxonomic status of North American A. cepistipes. To our knowledge, A. cepistipes has not been previously confirmed on P. trichocarpa in the U.S.A. or formally reported as a pathogen of any Populus species in North America. Continued studies are needed to determine the distribution, host range, and ecological role of A. cepistipes in riparian forests of the Pacific Northwest, while monitoring its populations under changing climates.

Phase integration bias in a motion grouping task.

The perception of the direction of global motion depends on our ability to integrate local motion signals over space and time. We examined motion binding using a task requiring integration of relative phase. Observers completed multiple tasks involving clockwise and counter clockwise motion in a stimulus comprising four sets of linearly arranged dots, two moving horizontally and two moving vertically along sinusoidal trajectories differing in phase. Noise jitter was added along the trajectory perpendicular to each dot's motion. The noise acts as a global grouping cue that improves direction discrimination, but surprisingly, the absence of noise causes consistent below-chance performance (Lorenceau, 1996). We explore this phenomenon and subsequently test the hypothesis that observers perceive reverse motion because their representation of the relative phase of the motion components is systematically biased. We employ a number of different objective and subjective measures of motion integration and measure the phenomenon in both younger and older adults. Taken together, the results presented in the current article demonstrate that noise can promote global grouping in the stimulus and that confident, incorrect responses can be observed in the absence of correct global grouping. Generally, the current result raises the possibility that an integration bias could exist in other motion tasks.

Perceptual learning of detection of textures in noise.

We examined whether the effects of practice on visual detection are stimulus specific and whether practice alters response bias. Eighty-four subjects performed yes-no detection of band-limited noise patterns (textures) in two levels of external noise, on two consecutive days. On day 2, one-half of the observers switched to novel textures. Texture contrast was varied on signal-present trials using the method of constant stimuli. The signal was present on 50% of the trials. We measured d', detection thresholds, and two measures of response criterion: a global criterion that was based on sensitivity at all signal levels (Jones et al., 2015) and a local criterion computed at a hit rate of 70% or 80% (Wenger & Rasche, 2006). Performance improved for both groups on day 2, indicating that improvement transferred to novel textures. Increases in d' were associated with a decrease in false alarms across days. The global criterion became less liberal and became more optimal (i.e., less biased) with practice; however, this effect was small and was not statistically significant in all conditions. The local criterion measure also became slightly less liberal with practice in most conditions, becoming more or less optimal depending on the hit rate at which it was computed. Overall, the effects of practice on sensitivity in a visual detection task generalized to novel patterns. In addition, we found that practice had relatively small effects on response criterion, and the precise effects on response bias differed between global and local measures of criterion.

Evaluation of single molecule array digital immunoassay technology to quantitate neurofilament light chain.

Aim: Globally, neurodegeneration accounts for significant morbidity and mortality among the elderly. Millions of people are afflicted with neurodegenerative diseases, with the most notable cases attributed to Alzheimer's, Huntington's, amyotrophic lateral sclerosis and Parkinson's diseases. Sensitive assays that can detect proteopathic anomalies indicative of early neurodegeneration have remained elusive. Therefore, there is an urgent need for sensitive diagnostic and prognostic biomarker assays that can guide the therapeutic regimen in the clinic. Materials & methods: Single molecule array digital immunoassay platform has sensitivity about 1000-fold higher than traditional ligand binding assays. Consequently, we are now beginning to implement ultrasensitive techniques in bioanalysis. Conclusion: In the current study, we evaluated single molecule array technology and report specifications to quantitate neurofilament light chain, a bona-fide biomarker for neurodegeneration. Preliminary neurofilament light screening results from 100 human geriatric cerebrospinal fluid samples displayed huge biological variation and warrants further investigation.

Evaluation of sample stability for cellular kinetics and pharmacodynamic flow cytometry methods.

We evaluated the sample stability for a cellular kinetics and a pharmacodynamic flow cytometry methods. First, the blood collection tubes were compared for the enumeration of chimeric antigen receptor-T cells in human whole blood. Blood samples with chimeric antigen receptor-T cells were stable up to 3 days at room temperature in both conventional EDTA and Cyto-Chex® blood collection tubes (Streck Laboratories, NE, USA), but with better consistency in Cyto-Chex-BCT than conventional EDTA tubes. Second, sample storage temperatures were compared for the basophil activation test in human whole blood samples. The samples were stable up to 3 days for basophil activation test when stored at refrigerator temperature, but not stable when stored at room temperature. It is crucial during the development of method to evaluate all the variables which might impact sample integrity.

Sensitivity to curvature deformations along closed contours.

Human observers are exquisitely sensitive to curvature deformations along a circular closed contour (Wilkinson, Wilson, & Habak, 1998; Hess, Wang, & Dakin, 1999; Loffler, Wilson, & Wilkinson, 2003). Such remarkable sensitivity has been attributed to the curvature encoding scheme used by V4 neurons, which typically are assumed to be equally sensitive to curvature at all polar angles (Pasupathy & Connor, 2001, 2002; Carlson, Rasquinha, Zhang, & Connor, 2011). To test the assumption that detection thresholds for curvature deformations are invariant across polar angles, we used a novel stimulus class we call Difference of Gaussian (DoG) contours that allowed us to independently manipulate the amplitude, angular frequency, and polar angle of curvature of a closed-contour shape while measuring contour-curvature thresholds. Our results demonstrate that (a) detection thresholds were higher when observers were uncertain about the location of the curvature deformation, but on average, thresholds did not vary significantly across 24 polar angles; (b) the direction and magnitude of the oblique effect varies across individuals; (c) there is a strong association between detecting a contour deformation and identifying its location; (d) curvature detectors may serve as labeled lines.

Environmental variables associated with Nothophaeocryptopus gaeumannii population structure and Swiss needle cast severity in Western Oregon and Washington.

The environment has a strong influence on the abundance and distribution of plant pathogenic organisms and plays a major role in plant disease. Climatological factors may also alter the dynamics of the interactions between plant pathogens and their hosts. Nothophaeocryptopus (=Phaeocryptopus) gaeumannii, the causal agent of Swiss needle cast (SNC) of Douglas-fir, is endemic to western North America where it exists as two sympatric, reproductively isolated lineages. The abundance of this fungus and the severity of SNC are strongly influenced by climate. We used statistical and population genetic analyses to examine relationships between environment, pathogen population structure, and SNC severity. Although N. gaeumannii Lineage 2 in western Oregon and Washington was most abundant where SNC symptoms were most severe, we did not detect a significant relationship between Lineage 2 and disease severity. Warmer winter temperatures were inversely correlated with foliage retention (AFR) and positively correlated with the relative abundance of Lineage 2 (PL2). However when distance inland, which was strongly correlated with both AFR and PL2, was included in the model, there was no significant relationship between Lineage 2 and AFR. Spring/early summer dew point temperatures also were positively associated with total N. gaeumannii abundance (colonization index (CI)) and inversely correlated with AFR. Warmer summer mean temperatures were associated with lower CI and higher AFR. Our results suggest that the two lineages have overlapping environmental optima, but slightly different tolerance ranges. Lineage 2 was absent from more inland sites where winters are colder and summers are warm and dry, while Lineage 1 occurred at most sites across an environmental gradient suggesting broader environmental tolerance. These relationships suggest that climate influences the abundance and distribution of this ecologically important plant pathogen and may have played a role in the evolutionary divergence of these two cryptic fungal lineages.

Importance of probe design for bioanalysis of oligonucleotides using hybridization-based LC-fluorescence assays.

Aim: The importance of the length and/or structure of fluorescently labeled PNA (peptide nucleic acid) probes for quantitative determination of oligodeoxynucleotides (ODNs) is demonstrated in human plasma using hybridization-based LC-fluorescence assays. The length of the PNA probes impacts the peak shape and chromatographic separation of the resulting PNA/ODN hybridization complexes and affects assay sensitivity, dynamic range and carryover. Methods: For quantitative determination of an 18-mer phosphodiester ODN (DNL1818) in human plasma, an assay utilizing an Atto dye-labeled 12-mer PNA probe provided a linear quantitation range of 0.1-50 ng/ml with excellent accuracy and precision (within -5.3-7.73%). Conclusion: This method provides a convenient method for sensitive and specific quantification of ODNs in biological matrix with limited sample volume and no special extraction.

12th GCC Closed Forum: critical reagents; oligonucleotides; CoA; method transfer; HRMS; flow cytometry; regulatory findings; stability and immunogenicity.

The 12th GCC Closed Forum was held in Philadelphia, PA, USA, on 9 April 2018. Representatives from international bioanalytical Contract Research Organizations were in attendance in order to discuss scientific and regulatory issues specific to bioanalysis. The issues discussed at the meeting included: critical reagents; oligonucleotides; certificates of analysis; method transfer; high resolution mass spectrometry; flow cytometry; recent regulatory findings and case studies involving stability and nonclinical immunogenicity. Conclusions and consensus from discussions of these topics are included in this article.

Evaluating spatiotemporal interactions between shapes.

Spatiotemporal interactions between stimuli can alter the perceived curvature along the outline of a shape (Habak, Wilkinson, Zakher, & Wilson, 2004; Habak, Wilkinson, & Wilson, 2006). To better understand these interactions, we used a forward and backward masking paradigm with radial frequency (RF) contours while measuring RF detection thresholds. In Experiment 1, we presented a mask alongside a target contour and altered the stimulus onset asynchrony between this target-mask pair and a temporal mask. We found that a temporal mask increased thresholds when it preceded the target-mask stimulus by 130-180 ms but decreased thresholds when it followed the target-stimulus mask by 180 ms. Furthermore, Experiment 2 demonstrated that the effects of temporal and spatial masks are approximately additive. We discuss these findings in relation to theories of transient and sustained channels in vision.

Recommendations for classification of commercial LBA kits for biomarkers in drug development from the GCC for bioanalysis.

Over the last decade, the use of biomarker data has become integral to drug development. Biomarkers are not only utilized for internal decision-making by sponsors; they are increasingly utilized to make critical decisions for drug safety and efficacy. As the regulatory agencies are routinely making decisions based on biomarker data, there has been significant scrutiny on the validation of biomarker methods. Contract research organizations regularly use commercially available immunoassay kits to validate biomarker methods. However, adaptation of such kits in a regulated environment presents significant challenges and was one of the key topics discussed during the 12th Global Contract Research Organization Council for Bioanalysis (GCC) meeting. This White Paper reports the GCC members' opinion on the challenges facing the industry and the GCC recommendations on the classification of commercial kits that can be a win-win for commercial kit vendors and end users.