Brexanolone Treatment in a Real-World Patient Population: A Case Series and Pilot Feasibility Study of Precision Neuroimaging

PURPOSE/BACKGROUND

Brexanolone is approved for postpartum depression (PPD) by the United States Food and Drug Administration. Brexanolone has outperformed placebo in clinical trials, but less is known about the efficacy in real-world patients with complex social and medical histories. Furthermore, the impact of brexanolone on large-scale brain systems such as changes in functional connectivity (FC) is unknown.

METHODS/PROCEDURES

We tracked changes in depressive symptoms across a diverse group of patients who received brexanolone at a large medical center. Edinburgh Postnatal Depression Scale (EPDS) scores were collected through chart review for 17 patients immediately prior to infusion through approximately 1 year postinfusion. In 2 participants, we performed precision functional neuroimaging (pfMRI), including before and after treatment in 1 patient. pfMRI collects many hours of data in individuals for precision medicine applications and was performed to assess the feasibility of investigating changes in FC with brexanolone.

FINDINGS/RESULTS

The mean EPDS score immediately postinfusion was significantly lower than the mean preinfusion score (mean change [95% CI]: 10.76 [7.11-14.40], t (15) = 6.29, P < 0.0001). The mean EPDS score stayed significantly lower at 1 week (mean difference [95% CI]: 9.50 [5.23-13.76], t (11) = 4.90, P = 0.0005) and 3 months (mean difference [95% CI]: 9.99 [4.71-15.27], t (6) = 4.63, P = 0.0036) postinfusion. Widespread changes in FC followed infusion, which correlated with EPDS scores.

IMPLICATIONS/CONCLUSIONS

Brexanolone is a successful treatment for PPD in the clinical setting. In conjunction with routine clinical care, brexanolone was linked to a reduction in symptoms lasting at least 3 months. pfMRI is feasible in postpartum patients receiving brexanolone and has the potential to elucidate individual-specific mechanisms of action.

Functional parcellation of the neonatal cortical surface

The cerebral cortex is organized into distinct but interconnected cortical areas, which can be defined by abrupt differences in patterns of resting state functional connectivity (FC) across the cortical surface. Such parcellations of the cortex have been derived in adults and older infants, but there is no widely used surface parcellation available for the neonatal brain. Here, we first demonstrate that existing parcellations, including surface-based parcels derived from older samples as well as volume-based neonatal parcels, are a poor fit for neonatal surface data. We next derive a set of 283 cortical surface parcels from a sample of n = 261 neonates. These parcels have highly homogenous FC patterns and are validated using three external neonatal datasets. The Infomap algorithm is used to assign functional network identities to each parcel, and derived networks are consistent with prior work in neonates. The proposed parcellation may represent neonatal cortical areas and provides a powerful tool for neonatal neuroimaging studies.

Neonatal neural responses to novelty related to behavioral inhibition at 1 year

Behavioral inhibition (BI), an early-life temperament characterized by vigilant responses to novelty, is a risk factor for anxiety disorders. In this study, we investigated whether differences in neonatal brain responses to infrequent auditory stimuli relate to children's BI at 1 year of age. Using functional magnetic resonance imaging (fMRI), we collected blood-oxygen-level-dependent (BOLD) data from N = 45 full-term, sleeping neonates during an adapted auditory oddball paradigm and measured BI from n = 27 of these children 1 year later using an observational assessment. Whole-brain analyses corrected for multiple comparisons identified 46 neonatal brain regions producing novelty-evoked BOLD responses associated with children's BI scores at 1 year of age. More than half of these regions (n = 24, 52%) were in prefrontal cortex, falling primarily within regions of the default mode or frontoparietal networks or in ventromedial/orbitofrontal regions without network assignments. Hierarchical clustering of the regions based on their patterns of association with BI resulted in two groups with distinct anatomical, network, and response-timing profiles. The first group, located primarily in subcortical and temporal regions, tended to produce larger early oddball responses among infants with lower subsequent BI. The second group, located primarily in prefrontal cortex, produced larger early oddball responses among infants with higher subsequent BI. These results provide preliminary insights into brain regions engaged by novelty in infants that may relate to later BI. The findings may inform understanding of anxiety disorders and guide future research. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Functional parcellation of the neonatal brain

The cerebral cortex is organized into distinct but interconnected cortical areas, which can be defined by abrupt differences in patterns of resting state functional connectivity (FC) across the cortical surface. Such parcellations of the cortex have been derived in adults and older infants, but there is no widely used surface parcellation available for the neonatal brain. Here, we first demonstrate that adult- and older infant-derived parcels are a poor fit with neonatal data, emphasizing the need for neonatal-specific parcels. We next derive a set of 283 cortical surface parcels from a sample of n=261 neonates. These parcels have highly homogenous FC patterns and are validated using three external neonatal datasets. The Infomap algorithm is used to assign functional network identities to each parcel, and derived networks are consistent with prior work in neonates. The proposed parcellation may represent neonatal cortical areas and provides a powerful tool for neonatal neuroimaging studies.

Multi-echo Acquisition and Thermal Denoising Advances Infant Precision Functional Imaging

The characterization of individual functional brain organization with Precision Functional Mapping has provided important insights in recent years in adults. However, little is known about the ontogeny of inter-individual differences in brain functional organization during human development, but precise characterization of systems organization during periods of high plasticity might be most influential towards discoveries promoting lifelong health. Collecting and analyzing precision fMRI data during early development has unique challenges and emphasizes the importance of novel methods to improve data acquisition, processing, and analysis strategies in infant samples. Here, we investigate the applicability of two such methods from adult MRI research, multi-echo (ME) data acquisition and thermal noise removal with Noise reduction with distribution corrected principal component analysis (NORDIC), in precision fMRI data from three newborn infants. Compared to an adult example subject, T2* relaxation times calculated from ME data in infants were longer and more variable across the brain, pointing towards ME acquisition being a promising tool for optimizing developmental fMRI. The application of thermal denoising via NORDIC increased tSNR and the overall strength of functional connections as well as the split-half reliability of functional connectivity matrices in infant ME data. While our findings related to NORDIC denoising are coherent with the adult literature and ME data acquisition showed high promise, its application in developmental samples needs further investigation. The present work reveals gaps in our understanding of the best techniques for developmental brain imaging and highlights the need for further developmentally-specific methodological advances and optimizations, towards precision functional imaging in infants.

A Novel Cognitive Training Program Targets Stimulus-Driven Attention to Alter Symptoms, Behavior, and Neural Circuitry in Pediatric Anxiety Disorders: Pilot Clinical Trial

Objective: Pediatric anxiety disorders are associated with increased stimulus-driven attention (SDA), the involuntary capture of attention by salient stimuli. Increased SDA is linked to increased activity in the right ventrolateral prefrontal cortex (rVLPFC), especially in the portion corresponding to the ventral attention network (VAN). In this study, we present a small clinical trial using a novel attention training program designed to treat pediatric anxiety by decreasing SDA and activity in the rVLPFC. Methods: Children ages 8-12 with anxiety disorders (n = 18) participated in eight sessions of attention training over a 4-week period. At baseline and after completing training, participants completed clinical anxiety measures and a battery of cognitive tasks designed to measure three different aspects of attention: SDA, goal-oriented attention, and threat bias. A subset of participants (n = 12) underwent baseline and post-training neuroimaging while engaged in an SDA task. Brain analyses focused on activity within the rVLPFC. Results: Parent (p < 0.001)-, child (p < 0.002)-, and clinician-rated (p < 0.02) anxiety improved significantly over the course of training. Training significantly altered SDA [F(1,92) = 8.88, corrected p-value (pcor) < 0.012, uncorrected p-value (puncor) < 0.004]. Anxiety improvement correlated with improvements in goal-directed attention [r(10) = 0.60, pcor < 0.12 puncor < 0.04]. Within an area of the rVLPFC corresponding to the cingulo-opercular network (CON), there was a main effect of training [F(1,20) = 6.75, pcor < 0.16, puncor < 0.02], with decreasing signal across training. There was a significant interaction between training and anxiety on this region's activity [F(1,20) = 9.48, pcor < 0.048, puncor < 0.006]. Post hoc testing revealed that post-training activity within this CON area correlated with residual anxiety [r(10) = 0.68, p < 0.02]. Conclusions: SDA and rVLPFC neural activity may be novel therapeutic targets in pediatric anxiety. After undergoing a training paradigm aimed at modifying this aspect of attention and its underlying neural circuitry, patients showed lower anxiety, changes in SDA and goal-oriented attention, and decreased activity in the CON portion of the rVLPFC.

A somato-cognitive action network alternates with effector regions in motor cortex

Motor cortex (M1) has been thought to form a continuous somatotopic homunculus extending down the precentral gyrus from foot to face representations1,2, despite evidence for concentric functional zones3 and maps of complex actions4. Here, using precision functional magnetic resonance imaging (fMRI) methods, we find that the classic homunculus is interrupted by regions with distinct connectivity, structure and function, alternating with effector-specific (foot, hand and mouth) areas. These inter-effector regions exhibit decreased cortical thickness and strong functional connectivity to each other, as well as to the cingulo-opercular network (CON), critical for action5 and physiological control6, arousal7, errors8 and pain9. This interdigitation of action control-linked and motor effector regions was verified in the three largest fMRI datasets. Macaque and pediatric (newborn, infant and child) precision fMRI suggested cross-species homologues and developmental precursors of the inter-effector system. A battery of motor and action fMRI tasks documented concentric effector somatotopies, separated by the CON-linked inter-effector regions. The inter-effectors lacked movement specificity and co-activated during action planning (coordination of hands and feet) and axial body movement (such as of the abdomen or eyebrows). These results, together with previous studies demonstrating stimulation-evoked complex actions4 and connectivity to internal organs10 such as the adrenal medulla, suggest that M1 is punctuated by a system for whole-body action planning, the somato-cognitive action network (SCAN). In M1, two parallel systems intertwine, forming an integrate-isolate pattern: effector-specific regions (foot, hand and mouth) for isolating fine motor control and the SCAN for integrating goals, physiology and body movement.

Network-specific selectivity of functional connections in the neonatal brain

The adult human brain is organized into functional brain networks, groups of functionally connected segregated brain regions. A key feature of adult functional networks is long-range selectivity, the property that spatially distant regions from the same network have higher functional connectivity than spatially distant regions from different networks. Although it is critical to establish the status of functional networks and long-range selectivity during the neonatal period as a foundation for typical and atypical brain development, prior work in this area has been mixed. Although some studies report distributed adult-like networks, other studies suggest that neonatal networks are immature and consist primarily of spatially isolated regions. Using a large sample of neonates (n = 262), we demonstrate that neonates have long-range selective functional connections for the default mode, fronto-parietal, and dorsal attention networks. An adult-like pattern of functional brain networks is evident in neonates when network-detection algorithms are tuned to these long-range connections, when using surface-based registration (versus volume-based registration), and as per-subject data quantity increases. These results help clarify factors that have led to prior mixed results, establish that key adult-like functional network features are evident in neonates, and provide a foundation for studies of typical and atypical brain development.

Effects of swine microRNA mimics on lipopolysaccharide (LPS) induced inflammatory changes in 3D4/21 cells

There have been limited studies focused on validation of swine microRNAs (miRNA) with mRNA targets. The objective of this study was to validate a defined set of targets using artificial miRNA mimics transfected into cell lines to confirm specific targets of endogenous miRNAs after administration of Escherichia coli lipopolysaccharide (LPS). Sixteen hours after mimic transfection of 3D4/21 cell lines, the cells were stimulated with 1 μg/ml LPS or phosphate-buffered saline (PBS). The cells were harvested and collected at 0, 1, 3, and 8 h post administration. The selected genes DAD1, IL8, and ESR, which are involved in known pathways of inflammation. and are predicted or validated human targets of either miR-146a, let-7a, or miR-22-3p. These were then evaluated by quantitative real-time-PCR (qRT-PCR) to verify microRNA-mRNA interaction in swine. Using the ROX reference dye, mRNA changes in expression were assessed using the comparative CT Method (ΔΔCT method) for normalization against the PBS control group. DAD1 and ESR1 were negatively regulated by miR-22-3p and miR-146a-5p, respectively in 3D4/21 cells after LPS stimulation. However, miR-146a-5p may play an indirect positive regulatory role of both DAD1 and IL8 mRNA expression. Furthermore, we found an inverse relationship between LPS stimulation compared with the let-7a-5p overexpression with DAD1. Our inflammation study provides new evidence on the roles and predicted targets of miR-146a, let-7a, and miR-22-3p in swine.

Whole-Brain Resting-State Functional Connectivity Patterns Associated With Pediatric Anxiety and Involuntary Attention Capture

BACKGROUND

Pediatric anxiety disorders are linked to dysfunction in multiple functional brain networks, as well as to alterations in the allocation of spatial attention. We used network-level analyses to characterize resting-state functional connectivity (rs-fc) alterations associated with 1) symptoms of anxiety and 2) alterations in stimulus-driven attention associated with pediatric anxiety disorders. We hypothesized that anxiety was related to altered connectivity of the frontoparietal, default mode, cingulo-opercular, and ventral attention networks and that anxiety-related connectivity alterations that include the ventral attention network would simultaneously be related to deviations in stimulus-driven attention.

METHODS

A sample of children (n = 61; mean = 10.6 years of age), approximately half of whom met criteria for a current anxiety disorder, completed a clinical assay, an attention task, and rs-fc magnetic resonance imaging scans. Network-level analyses examined whole-brain rs-fc patterns associated with clinician-rated anxiety and with involuntary capture of attention. Post hoc analyses controlled for comorbid symptoms.

RESULTS

Elevated clinician-rated anxiety was associated with altered connectivity within the cingulo-opercular network, as well as between the cingulo-opercular network and the ventral attention, default mode, and visual networks. Connectivity between the ventral attention and cingulo-opercular networks was associated with variation in both anxiety and stimulus-driven attention.

CONCLUSIONS

Pediatric anxiety is related to aberrant connectivity patterns among several networks, most of which include the cingulo-opercular network. These results help clarify the within- and between-network interactions associated with pediatric anxiety and its association with altered attention, suggesting that specific network connections could be targeted to improve specific altered processes associated with anxiety.

Minimally invasive ultrasound-guided technique for central venous catheterization via the external jugular vein in pigs

OBJECTIVE

To describe an ultrasound-guided technique for central venous catheter placement via the external jugular vein (EJV) in pigs.

ANIMALS

96 healthy Landrace-Poland China barrows (approx 16 weeks old with a mean weight of 70 kg).

PROCEDURES

Pigs were anesthetized. With ultrasound guidance, a needle was inserted into the EJV without a large incision or cutdown procedure. A guidewire was inserted through the needle into the vein. A modified Seldinger technique was used to advance a catheter into the vessel until the tip was in the cranial vena cava near the right atrium. A trocar was used to create a tunnel through the subcutaneous tissues from the catheter insertion site to between the dorsal borders of the scapulae. The free end of the catheter was passed through that tunnel. An extension was attached to the catheter and secured to the skin. Pigs were euthanized and underwent necropsy at completion of the study for which they were catheterized.

RESULTS

Central venous catheters were successfully placed in all 96 pigs and facilitated collection of serial blood samples with minimal stress. Catheters remained in place for a mean of 6 days (range, 4 to 10 days). Necropsy revealed abscesses along the subcutaneous catheter tract in 9 pigs. Twenty pigs had histologic evidence of phlebitis and fibroplasia in the cranial vena cava.

CONCLUSIONS AND CLINICAL RELEVANCE

The described technique, in combination with extensive socialization, allowed serial collection of blood samples with minimal stress and restraint and is an alternative to surgical cutdown procedures for catheter placement.

Microfluidic Separation of Canine Adipose-Derived Mesenchymal Stromal Cells

Mesenchymal stromal cells (MSCs) are potential treatments for a variety of veterinary medical conditions. However, clinical trials have often fallen short of expectations, due in part to heterogeneity and lack of characterization of the MSCs. Identification and characterization of subpopulations within MSC cultures may improve those outcomes. Therefore, the functional heterogeneity of different-sized subpopulations of MSCs was evaluated. A high-throughput, biophysical, label-free microfluidic sorting approach was used to separate subpopulations of canine adipose-derived MSCs (Ad-MSCs) based on size for subsequent characterization, as well as to evaluate the impact of culture conditions on their functional heterogeneity. We found that culture-expanded canine Ad-MSCs comprise distinct subpopulations: larger MSCs (mean diameter of 18.6 ± 0.2 μm), smaller MSCs (mean diameter of 15.3 ± 0.2 μm), and intermediate MSCs (mean diameter of 16.9 ± 0.1 μm). In addition, proliferation characteristics, senescence, and differentiation potential of canine Ad-MSCs are also dependent on cell size. We observed that larger MSCs proliferate more slowly, senesce at earlier passages, and are inclined to differentiate into adipocytes compared with smaller MSCs. Most importantly, these size-dependent functions are also affected by the presence of serum in the culture medium, as well as time in culture. Cell surface staining for MSC-specific CD44 and CD90 antigens showed that all subpopulations of MSCs are indistinguishable, suggesting that this criterion is not relevant to define subpopulations of MSCs. Finally, transcriptome analysis showed differential gene expression between larger and smaller subpopulations of MSCs. Larger MSCs expressed genes involved in cellular senescence such as cyclin-dependent kinase inhibitor 1A and smaller MSCs expressed genes that promote cell growth [mechanistic target of rapamycin 1 (mTORC1) pathway] and cell proliferation [myelocytomatosis (myc), e2f targets]. These results suggest that different subpopulations of MSCs have specific properties. Impact statement Clinical trials of mesenchymal stromal cells (MSCs) from veterinary species have often fallen short of expectations, due in part to heterogeneity and lack of characterization of the MSCs. A high-throughput, biophysical, label-free microfluidic sorting approach was used to separate subpopulations of canine adipose-derived MSCs (Ad-MSCs) based on size for subsequent characterization. Proliferation characteristics, senescence, and differentiation potential of canine Ad-MSCs are also dependent on cell size. Cell surface staining for MSC-specific cell surface markers showed that all subpopulations of MSCs are indistinguishable, suggesting that this criterion is not relevant to define subpopulations of MSCs.

Neonatal Brain Response to Deviant Auditory Stimuli and Relation to Maternal Trait Anxiety

OBJECTIVE

Excessive response to unexpected or "deviant" stimuli during infancy and early childhood represents an early risk marker for anxiety disorders. However, research has yet to delineate the specific brain regions underlying the neonatal response to deviant stimuli near birth and the relation to risk for anxiety disorders. The authors used task-based functional MRI (fMRI) to delineate the neonatal response to deviant stimuli and its relationship to maternal trait anxiety.

METHODS

The authors used fMRI to measure brain activity evoked by deviant auditory stimuli in 45 sleeping neonates (mean age, 27.8 days; 60% female; 64% African American). In 41 of the infants, neural response to deviant stimuli was examined in relation to maternal trait anxiety on the State-Trait Anxiety Inventory, a familial risk factor for offspring anxiety.

RESULTS

Neonates manifested a robust and widespread neural response to deviant stimuli that resembles patterns found previously in adults. Higher maternal trait anxiety was related to higher responses within multiple brain regions, including the left and right anterior insula, the ventrolateral prefrontal cortex, and multiple areas within the anterior cingulate cortex. These areas overlap with brain regions previously linked to anxiety disorders and other psychiatric illnesses in adults.

CONCLUSIONS

The neural architecture sensitive to deviant stimuli robustly functions in newborns. Excessive responsiveness of some circuitry components at birth may signal risk for anxiety and other psychiatric disorders.

Lipopolysaccharide (LPS) induced inflammatory changes to differentially expressed miRNAs of the host inflammatory response

In veterinary medicine, inflammation in swine is evaluated principally by clinical signs. This method is often unreliable when assessing large animal populations because of inconsistent interpretations of clinical observations. This study examined whether changes in miRNA expression can predict the severity of the inflammatory response in swine after administration of Escherichia coli lipopolysaccharide (LPS). Whole blood from swine challenged with LPS at 0.125 μg/kg to 2.0 μg/kg body weight was collected at 0, 1, 3, and 8 h post LPS-challenge. Mature miRNAs were extracted from plasma and quantitative real-time-PCR (qRT-PCR) was used to evaluate the 84 most abundant swine miRNAs found in plasma. The miRNA changes in expression were assessed using the comparative CT Method (ΔΔCT method) for normalization with an exogenous control. The results revealed that expression of ssc-let-7e-5p, ssc-mir-22-3p, and ssc-miR-146a-5p were the most significantly changed miRNA over the time course. At 1 h post-LPS, ssc-let-7e-5p decreased as the LPS dosage levels increased from 0.125 to 1.0 μg/kg. Similarly, as the LPS doses increased from 0.125 to 0.5 μg/kg, ssc-miR-22-3p levels significantly decreased at 1 h post-LPS. In the 2.0 μg/kg LPS, ssc-miR-146a-5p levels increased between 0 and 3 h post-LPS; however, expression was downregulated with a 145 % decrease from 3 to 8 h. The three miRNA biomarkers suggest potentially useful surrogate endpoints for the evaluation of inflammatory and endotoxemia responses in swine.

Attention Alterations in Pediatric Anxiety: Evidence From Behavior and Neuroimaging

BACKGROUND

Pediatric anxiety disorders involve greater capture of attention by threatening stimuli. However, it is not known if disturbances extend to nonthreatening stimuli, as part of a pervasive disturbance in attention-related brain systems. We hypothesized that pediatric anxiety involves greater capture of attention by salient, nonemotional stimuli, coupled with greater activity in the portion of the inferior frontal gyrus (IFG) specific to the ventral attention network (VAN).

METHODS

A sample of children (n = 129, 75 girls, mean 10.6 years of age), approximately half of whom met criteria for a current anxiety disorder, completed a task measuring involuntary capture of attention by nonemotional (square boxes) and emotional (angry and neutral faces) stimuli. A subset (n = 61) completed a task variant during functional magnetic resonance imaging. A priori analyses examined activity in functional brain areas within the right IFG, supplemented by a whole-brain, exploratory analysis.

RESULTS

Higher clinician-rated anxiety was associated with greater capture of attention by nonemotional, salient stimuli (F1,125 = 4.94, p = .028) and greater activity in the portion of the IFG specific to the VAN (F1,57 = 10.311, p = .002). Whole-brain analyses confirmed that the effect of anxiety during capture of attention was most pronounced in the VAN portion of the IFG, along with additional areas of the VAN and the default mode network.

CONCLUSIONS

The pathophysiology of pediatric anxiety appears to involve greater capture of attention to salient stimuli, as well as greater activity in attention-related brain networks. These results provide novel behavioral and brain-based targets for treatment of pediatric anxiety disorders.

Pharmacokinetic comparison of six anthelmintics in sheep, goats, and cattle

This study was initiated to determine whether a comparative pharmacokinetic (PK) approach could be used to expand the pool of approved anthelmintics for minor ruminant species. Accordingly, the PK profiles of six anthelmintics (levamisole, albendazole, fenbendazole, moxidectin, doramectin, and ivermectin) in sheep, goats, and cattle were determined. The PK values determined for each anthelmintic included T_max , T_last , C_max , AUC, AUC/dose, and C_max /dose. The results of this study demonstrate that a comparative PK approach does not show commonality in the way these six anthelmintics are individually processed by these three ruminants. While some drugs demonstrated identical PK profiles between sheep and goats, none of these drugs demonstrated PK profiles in sheep and goats comparable to the PK profiles found in cattle. The results from this study suggest drug approval across these three ruminants is not a viable concept. However, the resulting PK profiles for each combination of drug and ruminant species represents a new dataset that can be used to support the US FDA Center for Veterinary Medicine's Minor Use/Minor Species indexing process for drug approvals in minor species such as sheep and goats.

Overcontrol and neural response to errors in pediatric anxiety disorders

Multiple risk factors that may contribute to the development and severity of pediatric anxiety disorders, one of which is dimensional overcontrol. Overcontrol is a constellation of characteristics including heightened performance monitoring, inflexibility, perfectionism and aversion to making mistakes. In this study, we examined overcontrol in children with anxiety disorders and tested whether the underlying dimension of overcontrol specifically explains altered brain response to errors in pediatric anxiety disorders. Parent-reported scores of child overcontrol were collected in a sample of children (ages 8-12 years) with (n = 35) and without (n = 34) anxiety disorders and the relationship of overcontrol and anxiety symptoms to neural responding to errors during functional magnetic resonance imaging (fMRI) was examined. Results indicated childhood overcontrol was elevated in pediatric anxiety disorders and was significantly associated with anxiety severity, even when controlling for comorbid depression and ADHD. Additionally, overcontrol was associated with reduced neural response to errors versus correct responses in the bilateral dorsal anterior cingulate cortex (dACC) and insula, even when controlling for anxiety symptoms. Overcontrol may serve as an underlying mechanism associated with clinical pediatric anxiety that demonstrates significant associations with aberrant neural error responding. Overcontrol may be an underlying mechanism contributing to pediatric anxiety that could be targeted for early intervention.

Proteomics profiling of swine serum following lipopolysaccharide stimulation

RATIONALE

There are no approved animal drugs for management of inflammation in swine due to lack of validated animal models. To assess efficacy, it was essential to develop proteomics approaches to identify suitable biomarkers of inflammation as presented in this study.

METHODS

Serum samples were collected from a group of four pigs prior to (baseline) and 24 and 48 h following lipopolysaccharide (LPS) stimulation to reveal proteomic changes during inflammation. Two other pigs served as untreated controls. Proteins were separated by either one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) or two-dimensional (2D) gel electrophoresis (2DE) prior to analysis by nano-flow liquid chromatography (nLC) coupled to tandem mass spectrometry (MS/MS).

RESULTS

We identified 165 proteins using SDS-PAGE, of which 47 proteins were also detected by 2DE prior to nLC/MS/MS. More than half (72%) of all characterized proteins were modulated as a result of LPS stimulation, many of which are known to be involved with innate and adaptive immunity. Pig serum samples obtained 24 h after LPS initiation of inflammation showed protein modulations of serum albumin, serotransferrin, light and heavy immunoglobulin chains (IGs), and major acute phase proteins including haptoglobin (HPT), serum amyloid A2 (SAA2), C-reactive protein (CRP), β-2-glycoprotein 1 (B-2GP1), alpha-2-HS-glycoprotein (A2HS), α-1-antitrypsin (A1AT), and α-1-acid glycoprotein (A1AG). SAA2 was distinguished from the other SAA isoforms by the unique peptide sequence of SAA2.

CONCLUSIONS

The results provided proteomics analysis of swine serum due to LPS stimulation and indicated the importance of SAA2, which appears to be unique and may be regarded as a potential clinical diagnostic biomarker of inflammation.

Identification of swine protein biomarkers of inflammation-associated pain

This study sought to determine if proteins associated with pain in humans could be measured using a swine in vitro model of inflammation. This would constitute the first step towards using them as surrogate endpoints to help support effectiveness indications for investigational new animal drugs to control pain in swine. Swine whole blood samples were cultured in vitro with E. coli derived-lipopolysaccharide (LPS) or without LPS for 24 h. Supernatants from these cultures were collected to determine the concentration of proteins associated with pain and whether the levels were altered in response to LPS-induced inflammation. Bradykinin protein levels steadily increased over time due to LPS stimulation and returned to 0 h levels after 6 h of culture. Corticotrophin-releasing factor protein levels were not affected by LPS. Substance-P protein trended towards increasing concentrations after LPS stimulation, following a time-concentration profile similar to that observed with bradykinin. These results suggest that 2 biomarkers may be useful as surrogate endpoints for evaluation of pain.

Impact of ABCB1 genotype in Collies on the pharmacokinetics of R- and S-fexofenadine

Thirty-two Collies were used to determine the impact of ABCB1 genotype and phenotype on the plasma pharmacokinetics of fexofenadine's (Fex) R- and S-enantiomers after bolus Fex administration, as human P-gp exhibits stereoselectivity. Each Collie's ABCB1 genotype and ivermectin (IVM) sensitivity (phenotype) was determined prior to study enrolment. Wild-type (WT) Collies had lower plasma concentrations of the individual enantiomers as compared to heterozygous IVM nonsensitive (HNS), heterozygous IVM-sensitive (HS) and homozygous mutant (MUT) Collies. Based on pairwise statistical comparison, WT Collies had statistically significantly lower (AUC_0-last ) and peak (C_max ) values compared to HS, HNS and MUT Collies. T_max was not influenced by genotype/phenotype. Inter-individual variability in PK metrics tended to be largest for WT Collies. Although the influence of genotype/phenotype on Fex PK occurred with the individual isomers, impairment of S-Fex absorption, particularly in the MUT dogs, exceeded that associated with R-Fex. Since Fex elimination occurs primarily via biliary excretion via a transporter other than P-glycoprotein, and based upon our understanding of Fex absorption kinetics, we attributed these differences primarily to the absorption portion of the profile. These differences are expressed in a stereo-specific manner. These results demonstrate the potential negative impact on estimates of drug effectiveness and toxicity, especially for P-gp substrates that do not exhibit Central Nervous System toxicities.

λ-Carrageenan initiates inflammation via activation of heterodimers TLR2/6 and TLR4/6

λ-Carrageenan (λCGN) is frequently used to model local inflammation, however, the mechanism by which λCGN functions has not been fully examined. Swine whole blood was stimulated with λCGN and biomarkers were evaluated. Monocyte Chemotactic Protein-1(MCP-1) and Interleukin-8 protein levels were increased, while Serum Amyloid A (SAA) and Tumor Necrosis Factor-α (TNFα) protein levels were unchanged. Gene expression of MCP-1, Phosphatidylinositol 3-Kinase, and Alveolar Macrophage Chemotactic–II were increased; gene expression of SAA, Interleukin-6, and TNFα were unchanged; and gene expression of Thrombospondin-2 Precursor were decreased. Assessment of which TLRs (Toll-Like Receptors) were involved in the λCGN activation pathway, HEK-293 cells transfected with one plasmid containing either TLR2 or TLR4, along with a second plasmid to release SEAP (secreted embryonic alkaline phosphatase) upon NFκB activation were stimulated with λCGN. TLR2 and TLR4 both showed increased SEAP release after λCGN stimulation. The lack of TNFα production after λCGN stimulation suggested that it was not working through a classic TLR4 homodimer. To determine if a common mechanism could explain these results, RNA silencing studies were initiated. TLR6 was silenced in SEAP HEK-293 cells containing a plasmid for either TLR2 or TLR4. In both cell lines where TLR6 was silenced, λCGN was unable to induce a SEAP response, while these cells maintained responsiveness to a TLR1/2 ligand and a TLR 4 ligand, respectively. These results suggest that λCGN initiates inflammation via TLR2/6 and TLR4/6 heterodimers.

Influence of P-glycoprotein on the disposition of fexofenadine and its enantiomers

OBJECTIVES

P-glycoprotein (P-gp) is responsible for the efflux of a broad variety of human and veterinary drugs. Canine P-gp polymorphisms alter drug disposition and toxicity, but their impact on the disposition of enantiomeric drugs is unknown. Using fexofenadine as a model compound, we developed and validated HPLC-fluorescence methods to determine the effect of P-gp on the disposition of fexofenadine and its enantiomers.

METHODS

A chiral CD-Ph column was used for the separation of (R) and (S)-fexofenadine. Determination of racemic fexofenadine was achieved on an XDB-CN column. Fexofenadine and its enantiomers were detected by fluorescence at the excitation wavelength of 220 nm and emission wavelength of 300 nm. These methods were used to measure concentrations of fexofenadine and its enantiomers in Collie plasma after oral administration.

KEY FINDINGS

This study demonstrates that P-gp prefers to transport (S)-fexofenadine, and P-gp deficiency causes the increase in both (R)-fexofenadine and (S)-fexofenadine in plasma. Racemic fexofenadine, (R)-fexofenadine and (S)-fexofenadine were increased in ABCB1-1Δ Collies (118.7, 72.0 and 48.3 ng/ml) compared to wild-type Collies (25.0, 16.5 and 7.7 ng/ml) at 1 h postadministration. The results demonstrate that the stereoselectivity of P-gp plays a key role in the disposition of fexofenadine enantiomers.

CONCLUSIONS

The information derived from this drug model will be used to determine whether additional safety or efficacy requirements are necessary for enantiomeric drugs that would be used in dogs or humans.

Biomarkers in Veterinary Medicine

This article summarizes the relevant definitions related to biomarkers; reviews the general processes related to biomarker discovery and ultimate acceptance and use; and finally summarizes and reviews, to the extent possible, examples of the types of biomarkers used in animal species within veterinary clinical practice and human and veterinary drug development. We highlight opportunities for collaboration and coordination of research within the veterinary community and leveraging of resources from human medicine to support biomarker discovery and validation efforts for veterinary medicine.

Inhalation anesthesia induced by isoflurane alters penicillin disposition in swine tissues

Twelve healthy swine were dosed with penicillin G intramuscularly. Fluids and tissues samples were collected at the end of two periods of general anesthesia, performed 24 h apart. Tissue samples were collected by minimally invasive laparoscopy under general anesthesia at 8 and 28 h postdose. Four nonanesthetized, penicillin-treated pigs were euthanized at 8 h postdose, and a second set of four similarly treated control pigs were sacrificed 28 h postdose. Liver penicillin tissue concentrations from animals that underwent anesthesia and laparoscopic tissue collection had tissue concentrations that were higher than nonanesthetized pigs at both time points. Urine, plasma, kidney, skeletal, and cardiac muscle showed no differences between the two groups. Laparoscopic tissue collection under general anesthesia in swine induces physiological changes that cause alterations in tissue pharmacokinetics not seen in conscious animals.

Comparison of serum protein concentrations to clinical observations during lipopolysaccharide (LPS) induced inflammation in swine

The serum kinetic profile of the proteins MCP1 (CCL-2), C - reactive protein (CRP), and Serum Amyloid A (SAA) were compared to clinical observations in swine given a single i.v. administration of lipopolysaccharide (LPS; 2 μg/kg). Blood samples were collected at 0, 1, 3, 6, 8, & 24 hr after LPS administration using an in-dwelling catheter inserted prior to LPS administration. Serum protein concentrations were determined using species-specific ELISA. Clinical observations include temperature, respiration rate (RR), skin redness (SR), lethargy, and respiratory character (RC). LPS administration failed to result in elevated CRP and SAA levels. MCP-1 was induced within 1 h of LPS administration, and remained elevated through 8 h, returning to baseline values by 24 h post-LPS. The kinetics of MCP1 protein differ from that of MCP1 mRNA, which exhibits elevated levels through 48 h post LPS (Peters et al, Vet Immol Immunopath, 2014, 148: 236–242). The clinical results suggest that the administered challenge resulted in toxicity beyond the expected systemic inflammatory response. However the results also suggest that MCP1 may be a serum protein biomarker of inflammation associated with severe endotoxicity and RR, RC, SR and lethargy may be clinical measures that can be used to qualify analytical measures such as MCP1 as surrogate endpoints. These results further suggest the model needs to be refined. The discordant regulation of MCP1 protein and mRNA levels suggest additional molecular controls regulating MCP1 protein production.

Characterization of the inflammatory effects of λ-carrageenan at the genomic and proteomic levels

λ-Carrageenan (λCGN) is often used to model local inflammation, but the mechanism by which this compound functions at the genomic and proteomic level has not been delineated. Whole blood from swine was stimulated with λCGN to determine inflammatory biomarkers. We also utilized a HEK-293 (human embryonic kidney) cell line transfected with a SEAP (secreted embryonic alkaline phosphatase)-release plasmid to determine which TLR (Toll-Like Receptor; TLR) signaling cascade was stimulated. Results indicated that Monocyte Chemotactic Protein-1 gene expression and protein were increased by λCGN stimulation while Serum Amyloid A gene expression and protein remained unchanged. λCGN stimulation increased mRNA levels of Phosphatidylinositol 3-Kinase and Alveolar Macrophage Chemotactic –II, decreased mRNA levels of Thrombospondin-2 Precursor, and had no effect on Interleukin-6 mRNA levels. λCGN stimulation increased protein levels of Interleukin-8 and had no effect on protein levels of Tumor Necrosis Factor-α. SEAP release from HEK-293 cells stimulated with λCGN indicated that both TLR2 and TLR4 signaling cascades were initiated. λCGN stimulation did not activate TLR3, TLR5, TLR7, TLR8, TLR9, NOD1, NOD2, Dectin-1a, or Dectin-1b. Experiments silencing either TLR1 or TLR6 to determine which TLR2 heterodimer is activated by λCGN are currently underway. In conclusion, while λCGN stimulation appears to signal through both the TLR2 and TLR4 pathways, significant differences exist between the genes and proteins stimulated by λCGN and pure TLR4 agonists such as E. coli-derived lipopolysaccharide.

Loperamide-induced expression of immune and inflammatory genes in Collies associated with ivermectin sensitivity

This study evaluated the impact of the ABCB1-1Δ mutation in Collies which exhibited toxicity toward ivermectin, on changes in gene expression when given the unrelated ABCB1 substrate loperamide, to identify potential biomarkers predictive of drug safety. Thirty-two healthy intact Collies consisting of dogs with either a wild-type, heterozygous mutant, or homozygous mutant genotype were used. Whole blood samples were collected from Collies at 0 or 5 h following administration of loperamide at a dose of 0.10 mg/kg. Whole-genome gene expression microarray was conducted to examine for changes in gene expression. Microarray analysis identified loperamide-induced changes in gene expression which were specifically associated with ivermectin-sensitive phenotypes in Collies possessing the ABCB1-1Δ mutation. Gene pathway analysis further demonstrated that the altered genes are involved in immunological disease, cell death and survival, and cellular development. Thirteen genes, including CCL8 and IL-8, were identified. Collie dogs harboring ABCB1-1Δ mutation which also exhibited toxicity toward ivermectin demonstrated systematic responses following loperamide treatment exhibited by altered expression of genes involved in immune and inflammatory signaling pathways. Genes such as CCL8 and IL-8 are potential biomarkers in whole blood that may predict the safety of loperamide in dogs with ABCB1-1∆ mutation associated with ivermectin sensitivity.

Identification of potential biomarkers of P-glycoprotein substrate neurotoxicity in transgenic mice expressing the mutated canine ABCB1 gene

OBJECTIVE

To identify biomarkers of P-glycoprotein (P-gp) substrate neurotoxicity in transgenic mice expressing the mutant canine ABCB1 gene (ABCB1-1Δ).

ANIMALS

8 ABCB1 knock-in and knock-out transgenic mice expressing the ABCB1-1Δ gene and 8 control mice expressing the wild-type canine ABCB1 gene (ABCB1-WT).

PROCEDURES

Groups including 2 ABCB1-1Δ mutant mice and 2 ABCB1-WT mice were administered the P-gp substrates ivermectin (10 mg/kg, SC), doramectin (10 mg/kg, SC), moxidectin (10 mg/kg, PO), or digoxin (1.53 mg/kg, SC). A toxicogenomic approach based on DNA microarrays was used to examine whole-genome expression changes in mice administered P-gp substrates.

RESULTS

Compared with control ABCB1-WT mice, ABCB1-1Δ mutant mice developed neurotoxic signs including ataxia, lethargy, and tremors similar to those reported for dogs with the ABCB1-1Δ mutation. Microarray analysis revealed that gene expression was altered in ABCB1-1Δ mutant mice, compared with findings for ABCB1-WT mice, following administration of the same P-gp substrates. Gene pathway analysis revealed that genes with a ≥ 2-fold gene expression change were associated with behavior and nervous system development and function. Moreover, 34 genes were altered in the ABCB1-1Δ mutant mice in all 4 drug treatment groups. These genes were also associated with behavior, which was identified as the top-ranked gene network.

CONCLUSIONS AND CLINICAL RELEVANCE

These study data have facilitated understanding of the molecular mechanisms of neurotoxicosis in ABCB1-1Δ mutant mice following exposure to various P-gp substrates. Some genes appear to be potential biomarkers of P-gp substrate neurotoxicity that might be used to predict the safety of those drugs in dogs with the ABCB1-1Δ mutation.

Measurement of the cosmic microwave background polarization lensing power spectrum with the POLARBEAR experiment

Gravitational lensing due to the large-scale distribution of matter in the cosmos distorts the primordial cosmic microwave background (CMB) and thereby induces new, small-scale B-mode polarization. This signal carries detailed information about the distribution of all the gravitating matter between the observer and CMB last scattering surface. We report the first direct evidence for polarization lensing based on purely CMB information, from using the four-point correlations of even- and odd-parity E- and B-mode polarization mapped over ∼30 square degrees of the sky measured by the POLARBEAR experiment. These data were analyzed using a blind analysis framework and checked for spurious systematic contamination using null tests and simulations. Evidence for the signal of polarization lensing and lensing B modes is found at 4.2σ (stat+sys) significance. The amplitude of matter fluctuations is measured with a precision of 27%, and is found to be consistent with the Lambda cold dark matter cosmological model. This measurement demonstrates a new technique, capable of mapping all gravitating matter in the Universe, sensitive to the sum of neutrino masses, and essential for cleaning the lensing B-mode signal in searches for primordial gravitational waves.

Immunophenotype and gene expression profile of mesenchymal stem cells derived from canine adipose tissue and bone marrow

Veterinary adult stem cell therapy is an emerging area of basic and clinical research. Like their human counterparts, veterinary mesenchymal stem cells (MSCs) offer many potential therapeutic benefits. The characterization of canine-derived MSCs, however, is poorly defined compared to human MSCs. Furthermore, little consensus exists regarding the expression of canine MSC cell surface markers. To address this issue, this study investigated characteristics of cultured canine MSCs derived from both adipose tissue and bone marrow. The canine MSCs were obtained from donors of various breeds and ages. A panel of cell surface markers for canine MSCs was selected based on current human and canine literature and the availability of canine-reactive antibodies. Using flow cytometry, canine MSCs were defined to be CD90(+)CD44(+)MHC I(+)CD14(-)CD29(-)CD34(-)MHC II(-). Canine MSCs were further characterized using real-time RT-PCR as CD105(+)CD73(+)CD14(+)CD29(+)MHC II(+)CD45(-) at the mRNA level. Among these markers, canine MSCs differed from canine peripheral blood mononuclear cells (PBMCs) by the absence of CD45 expression at the mRNA level. A novel high-throughput canine-specific PCR array was developed and used to identify changes in the gene expression profiles of canine MSCs. Genes including PTPRC, TNF, β2M, TGFβ1, and PDGFRβ, were identified as unique to canine MSCs as compared to canine PBMCs. Our findings will facilitate characterization of canine MSCs for use in research and clinical trials. Moreover, the high-throughput PCR array is a novel tool for characterizing canine MSCs isolated from different tissues and potentially from different laboratories.

Evidence for gravitational lensing of the cosmic microwave background polarization from cross-correlation with the cosmic infrared background

We reconstruct the gravitational lensing convergence signal from cosmic microwave background (CMB) polarization data taken by the Polarbear experiment and cross-correlate it with cosmic infrared background maps from the Herschel satellite. From the cross spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical significance of 4.0σ and indication of the presence of a lensing B-mode signal at a significance of 2.3σ. We demonstrate that our results are not biased by instrumental and astrophysical systematic errors by performing null tests, checks with simulated and real data, and analytical calculations. This measurement of polarization lensing, made via the robust cross-correlation channel, not only reinforces POLARBEAR auto-correlation measurements, but also represents one of the early steps towards establishing CMB polarization lensing as a powerful new probe of cosmology and astrophysics.

Neurotoxic effects of ivermectin administration in genetically engineered mice with targeted insertion of the mutated canine ABCB1 gene

OBJECTIVE

To develop in genetically engineered mice an alternative screening method for evaluation of P-glycoprotein substrate toxicosis in ivermectin-sensitive Collies.

ANIMALS

14 wild-type C57BL/6J mice (controls) and 21 genetically engineered mice in which the abcb1a and abcb1b genes were disrupted and the mutated canine ABCB1 gene was inserted.

PROCEDURES

Mice were allocated to receive 10 mg of ivermectin/kg via SC injection (n = 30) or a vehicle-only formulation of propylene glycol and glycerol formal (5). Each was observed for clinical signs of toxic effects from 0 to 7 hours following drug administration.

RESULTS

After ivermectin administration, considerable differences were observed in drug sensitivity between the 2 types of mice. The genetically engineered mice with the mutated canine ABCB1 gene had signs of severe sensitivity to ivermectin, characterized by progressive lethargy, ataxia, and tremors, whereas the wild-type control mice developed no remarkable effects related to the ivermectin.

CONCLUSIONS AND CLINICAL RELEVANCE

The ivermectin sensitivity modeled in the transgenic mice closely resembled the lethargy, stupor, disorientation, and loss of coordination observed in ivermectin-sensitive Collies with the ABCB1-1Δ mutation. As such, the model has the potential to facilitate toxicity assessments of certain drugs for dogs that are P-glycoprotein substrates, and it may serve to reduce the use of dogs in avermectin derivative safety studies that are part of the new animal drug approval process.

P-gp substrate-induced neurotoxicity in an Abcb1a knock-in/Abcb1b knock-out mouse model with a mutated canine ABCB1 targeted insertion

Certain dog breeds, especially Collies, are observed to exhibit neurotoxicity to avermectin drugs, which are P-glycoprotein (P-gp) substrates. This neurotoxicity is due to an ABCB1 gene mutation (ABCB1-1Δ) that results in non-functional P-gp expression. A developed Abcb1a knock-in/Abcb1b knock-out mouse model expressing the ABCB1-1Δ canine gene was previously reported and mice exhibited sensitivity upon ivermectin administration. Here, model and wild-type mice were administered P-gp substrates doramectin, moxidectin, and digoxin. While knock-in/knock-out mice exhibited ataxia, lethargy and tremor, wild-type mice remained unaffected. In addition, no neurotoxic clinical signs were observed in either mouse type administered domperidone, a P-gp substrate with no reported neurotoxicity in ABCB1-1Δ Collies. Overall, neurotoxic signs displayed by model mice closely paralleled those observed in ivermectin-sensitive Collies. This model can be used to identify toxic P-gp substrates with altered safety in dog populations and may reduce dog use in safety studies that are part of the drug approval process.

Development of a multiplex real-time PCR assay for the detection of ruminant DNA

The U.S. Food and Drug Administration (FDA) has previously validated a real-time PCR-based assay that is currently being used by the FDA and several state laboratories as the official screening method. Due to several shortcomings to the assay, a multiplex real-time PCR assay (MRTA) to detect three ruminant species (bovine, caprine, and ovine) was developed using a lyophilized bead design. The assay contained two primer or probe sets: a "ruminant" set to detect bovine-, caprine-, and ovine-derived materials and a second set to serve as an internal PCR control, formatted using a lyophilized bead design. Performance of the assay was evaluated against stringent acceptance criteria developed by the FDA's Center for Veterinary Medicine's Office of Research. The MRTA for the detection of ruminant DNA passed the stringent acceptance criteria for specificity, sensitivity, and selectivity. The assay met sensitivity and reproducibility requirements by detecting 30 of 30 complete feed samples fortified with meals at 0.1 % (wt/wt) rendered material from each of the three ruminant species. The MRTA demonstrated 100 % selectivity (0.0 % false positives) for negative controls throughout the assessment period. The assay showed ruggedness in both sample selection and reagent preparation. Second and third analyst trials confirmed the quality of the written standard operating procedure with consistency of results. An external laboratory participating in a peer-verification trial demonstrated 100 % specificity in identifying bovine meat and bone meal, while exhibiting a 0.03 % rate of false positives. The assay demonstrated equal levels of sensitivity and reproducibility compared with the FDA's current validated real-time PCR assay. The assay detected three prohibited species in less than 1.5 h of total assay time, a significant improvement over the current real-time assay. These results demonstrated this assay's suitability for routine regulatory use both as a primary screening tool and as a confirmatory test.

Biomarkers of inflammation in cattle determining the effectiveness of anti-inflammatory drugs

The impact of nonsteroidal anti-inflammatory drugs (NSAID) on prostaglandin E(2) (PGE(2)) production and cyclooxygenase 2 (COX-2) mRNA expression in bovine whole blood (WB) cultures stimulated by lipopolysaccharide (LPS) was determined, using the blood from six Holstein dairy cattle in various stages of lactation. Peak production of PGE(2) occurred 24 h after LPS stimulation but did not result in detectable concentrations of thromboxane B(2) (TXB(2)). The NSAID indomethacin, aspirin, flunixin meglumine, and 4-[5-phenyl-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzene sulfonamide (PTPBS; celecoxib analogue), along with dexamethasone, were all equally effective in reducing the concentration of PGE(2) in the bovine WB culture supernatants. Bradykinin exhibited peak supernatant concentrations 1 h after LPS stimulation. Dexamethasone and the NSAID used in this study were equally effective at inhibiting bradykinin production. Peak induction of COX-2 mRNA occurred 3 h post-LPS stimulation. However, neither dexamethasone nor any of the NSAID used in this study altered COX-2 mRNA concentrations. In contrast, aspirin, flunixin meglumine, and PTPBS reduced tumor necrosis factor-alpha (TNFalpha) mRNA concentration. These results demonstrate that bovine blood cells respond to NSAID therapy like other mammalian cells with respect to inhibition of PGE(2) production and suppression of TNF mRNA induction, but do not inhibit induction of COX-2 mRNA.

Detection of rendered meat and bone meals by PCR is dependent on animal species of origin and DNA extraction method

The capability of eight commercially available DNA extraction kits to extract bovine DNA originating in meat and bone meal from fortified feed was evaluated. Four different batches of bovine meat and bone meal (BMBM) were used for DNA extraction with the eight commercial DNA extraction kits. Within each kit, there were minimal differences in the batch-to-batch amounts of extracted DNA. There were differences between the kits in the amounts of DNA that could be extracted from the same amount of starting BMBM. These differences did not translate into differences in the amount of amplifiable DNA from BMBM-fortified dairy feed. Using a validated real-time PCR method, the kit yielding the highest amount extractable DNA was completely unable to yield a positive PCR result; one other kit was also unable to produce a positive PCR result from DNA extracted from BMBM-fortified feed. There was a complete lack of a correlation between the amount of bovine DNA isolated from BMBM by a given extraction kit compared with the relative amounts of DNA isolated from fortified animal feed as evidenced by the cycle threshold values generated using the real-time PCR method. These results demonstrate that extraction of DNA from processed animal protein is different for pure ingredients and fortified animal feeds. These results indicate that a method specifically developed using just animal-derived meat and bone meal may not yield a functional assay when used to detect animal tissues in complete animal feed.

Development, evaluation, and peer verification of a rapid real-time PCR method for the detection of animal material

Four real-time PCR assays that can be used with U.S.- and European Union-rendered materials to detect three ruminant species (bovine, caprine, and ovine) and a select set of avians (chicken, goose, and turkey) were developed. This method was evaluated against stringent acceptance criteria previously developed by the U.S. Food and Drug Administration, Center for Veterinary Medicine's Office of Research. Acceptance criteria for determining success used a statistical approach requiring a 90% probability of achieving the correct response, within a 95% confidence interval. A minimum detection level of 0.1% meat and bone meal (MBM) was required, consistent with the sensitivity of the validated PCR-based method currently used by the U.S. Food and Drug Administration as an aid in enforcement of the Agency's feed ban. PCR primer specificity was determined by using a panel of DNA samples derived from 16 different animal species. The method is able to detect 0.1% rendered material in complete feed in less than 1.5 h of total assay time, a significant improvement over the current method, which requires 7 to 8 h for completion. The real-time assay for the detection of animal material passed stringent acceptance criteria for sensitivity, selectivity, and specificity. The method also passed ruggedness, real-time platform, and second analyst trials. Two external laboratories participating in a peer-verification trial demonstrated 100% specificity in identifying bovine MBM, ovine MBM, or caprine meat meal, while exhibiting a 0.6% rate of false positives. These results demonstrated that this method was capable of being used by other laboratories.

Nonlinear electronic line shape determination in Yb3+-doped phosphate glass

Nonlinear refraction spectroscopy has been performed in Yb3+-doped phosphate glass to determinate the line shape of real and imaginary parts of n2 (n2' and n2"). The n2' spectrum presented an asymmetric feature due to the interference of resonant and nonresonant contributions, where the nonresonant term arises from the polarizability difference between excited and ground states (delta alpha). The measurements were performed in the transient regime to determine population dynamics and the pump saturation intensity at 975 nm (peak of the absorption spectrum). Because of the small quantum defect of Yb3+, we estimated that the magnitude of the thermal lens effect is approximately 20 times smaller than the population lens effect, caused by n2.

Assessment of two enzyme-linked immunosorbent assay tests marketed for detection of ruminant proteins in finished feed

The performance characteristics of two enzyme-linked immunosorbent assay (ELISA) test kits, ELISA Technologies' MELISA-Tek test and Tepnel BioSystems' BioKit for (Cooked) Species Identification test, designed to detect ruminant proteins in animal feed, were evaluated. The test kits were evaluated by using acceptance criteria developed by the U.S. Food and Drug Administration's Center for Veterinary Medicine Office of Research for evaluating selectivity, sensitivity, ruggedness, and specificity. The acceptance criteria for determining success used a statistical approach requiring a 90% probability of achieving the correct response within a 95% confidence interval. In practice, this measure requires the test to achieve the correct response 58 times for every 60 samples evaluated, or a 96.7% accuracy rate. A minimum detection level of 0.1% bovine meat and bone meal (BMBM) was required, consistent with the sensitivity of the analytical methods presently used by the U.S. Food and Drug Administration. Selectivity was assessed by testing 60 dairy feed samples that contained no added animal proteins; sensitivity was determined by evaluating 60 samples (per level of fortification) of this same feed that contained 0.025, 0.05, 0.1, 0.25, 0.5, 1, or 2% BMBM. The MELISA-Tek test passed the acceptance set-point criteria for selectivity assessment but failed the sensitivity assessment at all levels except at the 2% level. The MELISA-Tek test came close to passing at the 1% level, detecting true-positive findings at a rate of 93%, but failed at lower levels, in spite of the label claim of 0.5% sensitivity. The BioKit for (Cooked) Species Identification test detected only 2 of 17 samples fortified at the 2% BMBM level and failed to detect any other BMBM-fortified samples. The results of this evaluation indicate that neither test is adequate for regulatory use.

Validation of a PCR-based method for the detection of various rendered materials in feedstuffs using a forensic DNA extraction kit

A method trial was initiated to validate the use of a commercial DNA forensic kit to extract DNA from animal feed as part of a PCR-based method. Four different PCR primer pairs (one bovine pair, one porcine pair, one ovine primer pair, and one multispecies pair) were also evaluated. Each laboratory was required to analyze a total of 120 dairy feed samples either not fortified (control, true negative) or fortified with bovine meat and bone meal, porcine meat and bone meal (PMBM), or lamb meal. Feeds were fortified with the animal meals at a concentration of 0.1% (wt/wt). Ten laboratories participated in this trial, and each laboratory was required to evaluate two different primer pairs, i.e., each PCR primer pair was evaluated by five different laboratories. The method was considered to be validated for a given animal source when three or more laboratories achieved at least 97% accuracy (29 correct of 30 samples for 96.7% accuracy, rounded up to 97%) in detecting the fortified samples for that source. Using this criterion, the method was validated for the bovine primer because three laboratories met the criterion, with an average accuracy of 98.9%. The average false-positive rate was 3.0% in these laboratories. A fourth laboratory was 80% accurate in identifying the samples fortified with bovine meat and bone meal. A fifth laboratory was not able to consistently extract the DNA from the feed samples and did not achieve the criterion for accuracy for either the bovine or multispecies PCR primers. For the porcine primers, the method was validated, with four laboratories meeting the criterion for accuracy with an average accuracy of 99.2%. The fifth laboratory had a 93.3% accuracy outcome for the porcine primer. Collectively, these five laboratories had a 1.3% false-positive rate for the porcine primer. No laboratory was able to meet the criterion for accuracy with the ovine primers, most likely because of problems with the synthesis of the primer pair; none of the positive control DNA samples could be detected with the ovine primers. The multispecies primer pair was validated in three laboratories for use with bovine meat and bone meal and lamb meal but not with PMBM. The three laboratories had an average accuracy of 98.9% for bovine meat and bone meal, 97.8% for lamb meal, and 63.3% for PMBM. When examined on an individual laboratory basis, one of these four laboratories could not identify a single feed sample containing PMBM by using the multispecies primer, whereas the other laboratory identified only one PMBM-fortified sample, suggesting that the limit of detection for PMBM with this primer pair is around 0.1% (wt/wt). The results of this study demonstrated that the DNA forensic kit can be used to extract DNA from animal feed, which can then be used for PCR analysis to detect animal-derived protein present in the feed sample.

Evaluation of two commercial lateral-flow test kits for detection of animal proteins in animal feed

Performance characteristics were evaluated for two lateral-flow test kits, Reveal for Ruminant in Feed (Neogen Corporation) and FeedChek (Strategic Diagnostics Inc.), designed to detect ruminant or terrestrial animal proteins in feeds. The stringent acceptance criteria used were developed by the Center for Veterinary Medicine Office of Research to identify test kits with comparable selectivity and sensitivity to microscopy and PCR assay, the analytical methods used by the U.S. Food and Drug Administration (FDA). Guidelines were developed for evaluating the selectivity, sensitivity, ruggedness, and specificity of these kits. These guidelines further stated that ruggedness and specificity testing would be performed only after a test passed both the selectivity and sensitivity assessments. Acceptance criteria for determining success were developed using a statistical approach requiring 90% probability of achieving the correct response, within a 95% confidence interval. A minimum detection level of 0.1% bovine meat and bone meal, consistent with the sensitivity of the methods used by the FDA, was required. Selectivity was assessed by testing 60 dairy feed samples that contained no added animal proteins; sensitivity was determined by evaluating 60 samples (per level of fortification) of the same feed that contained 0.025, 0.05, 0.1, 0.25, 0.5, 1, or 2% bovine meat and bone meal. The Reveal test passed the selectivity assessment but failed the sensitivity assessment, detecting only samples fortified at the 2% level and then only 17 to 33% of those samples, when read according to the label directions. The FeedChek test passed the sensitivity assessment but failed the selectivity assessment, with rates for false-positive results ranging from 34 to 38%, depending on the user. The sensitivity of the Reveal test was affected by the concentration of trace minerals present in the feed; concentrations toward the high end of the normal range prevented the detection of true positive feed samples containing bovine meat and bone meal. Better sensitivity assessments were obtained when lamb meal was used either alone or in combination with bovine meat and bone meal. The FeedChek test was not affected by the concentration of trace minerals or by the type of animal meal used. These results indicate that neither of the two tests is adequate for routine regulatory use.

Evaluation of a rapid PCR-based method for the detection of animal material

A rapid PCR-based analytical method for detection of animal-derived materials in complete feed was developed. Using a commercially available DNA forensic kit for the extraction of DNA from animal feed, a sensitive method was developed that was capable of detecting as little as 0.03% bovine meat and bone meal in complete feed in under 8 h of total assay time. The reduction in assay time was accomplished by reducing the DNA extraction time to 2 h and using the simpler cleanup procedure of the kit. Assay sensitivity can be increased to 0.006% by increasing the DNA extraction time to an overnight incubation of approximately 16 h. Examination of dairy feed samples containing either bovine meat and bone meal, porcine meat and bone meal, or lamb meal at a level of 0.1% (wt/wt basis) suggested that this method may be suitable for regulatory uses. The adoption of this commercially available kit for use with animal feeds yields an assay that is quicker and simpler to perform than a previously validated assay for the detection of animal proteins in animal feed.