Risk factors associated with physical therapist burnout: a systematic review.

BACKGROUND: Studies consistently suggest that work as a physical therapist is associated with burnout, yet no review of the contributing factors has been conducted. OBJECTIVE: To identify and examine the risk factors associated with physical therapist burnout. DATA SOURCES: PubMed, Embase, CINAHL, and the Cochrane Library were searched from inception to May 2020. ELIGIBILITY CRITERIA: Quantitative studies of physical therapists in clinical practice who experience burnout symptoms or syndrome. DATA EXTRACTION AND DATA SYNTHESIS: Risk factors such as characteristics of the participant, environment, structures, and experiences that demonstrate a significant predisposition to burnout were extracted. The modified Downs and Black checklist was used to identify risk of bias. RESULTS: Forty-six studies (8717 participants) were included. The risk of bias assessment determined all were of fair or poor quality. Fifty-three risk factors were identified, with four being classified as unavoidable and forty-nine determined as avoidable. The avoidable risk factors were further categorized as either structural/organizational (32%), psychological/emotional (19%), environmental (19%), or sociodemographic (13%). LIMITATIONS: A risk factor's importance may not correlate with its prevalence, and the low-quality studies limit the ability to make definitive conclusions. CONCLUSION: A significant amount of literature has identified a wide variety of risk factors. The majority are avoidable, and the effect and degree to which each risk factor contributes to burnout varies. The identified risk factors can help develop targeted prevention and intervention strategies for the benefit of physical therapists, organizations, and policymakers. FUNDING: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO CRD42020136356.

Evaluation of a novel quantitative canine species-specific point-of-care assay for C-reactive protein.

BACKGROUND: Species-specific point-of-care tests (POCT) permit a rapid analysis of canine C-reactive protein (CRP), enabling veterinarians to include CRP in clinical decisions. Aim of the study was to evaluate a novel POCT for canine CRP (Point Strip™ Canine CRP Assay) run on a small in-house-analyzer (Point Reader™ V) using lithium heparin plasma and to compare assay performance to an already established canine CRP assay (Gentian Canine CRP Immunoassay) run on two different bench top analyzers serving as reference methods (ABX Pentra 400, AU 5800). Linearity was assessed by stepwise dilution of plasma samples with high CRP concentrations. Limit of quantification (LoQ) was determined by repeated measurements of samples with low CRP concentrations. Coefficient of variation (CV) at low (10-50 mg/l), moderate (50-100 mg/l), and high (100-200 mg/l) CRP concentrations was investigated as well as possible interferences. Method comparison study was performed using 45 samples of healthy and diseased dogs. Quality criteria were fulfilled if the total observed error (TEobs = 2CV% + bias%) was below the minimal total allowable error of 44.4% (TE min). Additionally, a reference range (n = 60 healthy dogs) was established. RESULTS: Linearity was present at CRP concentrations of 10-132 mg/l (≙ 361 mg/l CRP with reference method) with a LoQ set at 10 mg/l. At moderate to high CRP concentrations, intra- and inter-assay CVs were ≤ 8% and ≤ 11% respectively, while CVs ≤ 22% and ≤ 28% were present at low concentrations. No interferences were observed at concentrations of 4 g/l hemoglobin, 800 mg/l bilirubin and 8 g/l triglycerides. Method comparison study demonstrated an excellent correlation with both reference methods (r = 0.98 for ABX Pentra 400; 0.99 for AU 5800), though revealing a proportional bias of 19.7% (ABX Pentra 400) and 10.7% (AU 5800) respectively. TEobs was 26.7-31.9% and 16.7-21.9% and thus < TEmin. Healthy dogs presented with CRP values ≤11.9 mg/l. CONCLUSIONS: The POCT precisely detects canine CRP at clinically relevant moderate and high CRP concentrations. The assay correlates well with both reference methods. Due to the bias, however, follow-up examinations should be performed with the same assay and analyzer.

Discovery of a Potent, Selective T-type Calcium Channel Blocker as a Drug Candidate for the Treatment of Generalized Epilepsies.

We report here the discovery and pharmacological characterization of N-(1-benzyl-1H-pyrazol-3-yl)-2-phenylacetamide derivatives as potent, selective, brain-penetrating T-type calcium channel blockers. Optimization focused mainly on solubility, brain penetration, and the search for an aminopyrazole metabolite that would be negative in an Ames test. This resulted in the preparation and complete characterization of compound 66b (ACT-709478), which has been selected as a clinical candidate.

Milestones to the Discovery of T-type Calcium Channel Blockers for the Treatment of Generalized Epilepsies.

We describe the discovery and optimization of new, brain-penetrant T-type calcium channel blockers. We present optimized compounds with excellent efficacy in a rodent model of generalized absence-like epilepsy. Along the fine optimization of a chemical series with a pharmacological target located in the CNS (target potency, brain penetration, and solubility), we successfully identified an Ames negative aminopyrazole as putative metabolite of this compound series. Our efforts culminated in the selection of compound 20, which was elected as a preclinical candidate.

Discovery and evaluation of Cav3.2-selective T-type calcium channel blockers.

We identified and characterized a series of pyrrole amides as potent, selective Cav3.2-blockers. This series culminated with the identification of pyrrole amides 13b and 26d, with excellent potencies and/or selectivities toward the Cav3.1- and Cav3.3-channels. These compounds display poor physicochemical and DMPK properties, making their use difficult for in vivo applications. Nevertheless, they are well-suited for in vitro studies.

Discovery and evaluation of Cav3.1-selective T-type calcium channel blockers.

We identified and characterized a series of pyrazole amides as potent, selective Cav3.1-blockers. This series culminated with the identification of pyrazole amides 5a and 12d, with excellent potencies and/or selectivities toward the Cav3.2- and Cav3.3-channels. This compound displays poor DMPK properties, making its use difficult for in vivo applications. Nevertheless, this compound as well as analogous ones are well-suited for in vitro studies.

Structure-Activity Relationship, Drug Metabolism and Pharmacokinetics Properties Optimization, and in Vivo Studies of New Brain Penetrant Triple T-Type Calcium Channel Blockers.

Despite the availability of numerous antiepileptic drugs, 20-30% of epileptic patients are pharmacoresistant with seizures not appropriately controlled. Consequently, new strategies to address this unmet medical need are required. T-type calcium channels play a key role in neuronal excitability and burst firing, and selective triple T-type calcium channel blockers could offer a new way to treat various CNS disorders, in particular epilepsy. Herein we describe the identification of new 1,4-benzodiazepines as brain penetrant and selective triple T-type calcium channel blockers. From racemic hit 4, optimization work led to the preparation of pyridodiazepine 31c with improved physicochemical properties, solubility, and metabolic stability. The racemic mixture was separated by chiral preparative HPLC, and the resulting lead compound (3R,5S)-31c showed promising efficacy in the WAG/Rij-rat model of generalized nonconvulsive absence-like epilepsy.

Preparation, Antiepileptic Activity, and Cardiovascular Safety of Dihydropyrazoles as Brain-Penetrant T-Type Calcium Channel Blockers.

A series of dihydropyrazole derivatives was developed as potent, selective, and brain-penetrating T-type calcium channel blockers. An optimized derivative, compound 6c, was advanced to in vivo studies, where it demonstrated efficacy in the WAG/Rij rat model of generalized nonconvulsive, absence-like epilepsy. Compound 6c was not efficacious in the basolateral amygdala kindling rat model of temporal lobe epilepsy, and it led to prolongation of the PR interval in ECG recordings in rodents.

The endocrine stress response is linked to one specific locus on chromosome 3 in a mouse model based on extremes in trait anxiety.

BACKGROUND: The hypothalamic-pituitary-adrenal (HPA) axis is essential to control physiological stress responses in mammals. Its dysfunction is related to several mental disorders, including anxiety and depression. The aim of this study was to identify genetic loci underlying the endocrine regulation of the HPA axis. METHOD: High (HAB) and low (LAB) anxiety-related behaviour mice were established by selective inbreeding of outbred CD-1 mice to model extremes in trait anxiety. Additionally, HAB vs. LAB mice exhibit comorbid characteristics including a differential corticosterone response upon stress exposure. We crossbred HAB and LAB lines to create F1 and F2 offspring. To identify the contribution of the endocrine phenotypes to the total phenotypic variance, we examined multiple behavioural paradigms together with corticosterone secretion-based phenotypes in F2 mice by principal component analysis. Further, to pinpoint the genomic loci of the quantitative trait of the HPA axis stress response, we conducted genome-wide multipoint oligogenic linkage analyses based on Bayesian Markov chain Monte Carlo approach as well as parametric linkage in three-generation pedigrees, followed by a two-dimensional scan for epistasis and association analysis in freely segregating F2 mice using 267 single-nucleotide polymorphisms (SNPs), which were identified to consistently differ between HAB and LAB mice as genetic markers. RESULTS: HPA axis reactivity measurements and behavioural phenotypes were represented by independent principal components and demonstrated no correlation. Based on this finding, we identified one single quantitative trait locus (QTL) on chromosome 3 showing a very strong evidence for linkage (2ln (L-score) > 10, LOD > 23) and significant association (lowest Bonferroni adjusted p < 10-28) to the neuroendocrine stress response. The location of the linkage peak was estimated at 42.3 cM (95% confidence interval: 41.3 - 43.3 cM) and was shown to be in epistasis (p-adjusted < 0.004) with the locus at 35.3 cM on the same chromosome. The QTL harbours genes involved in steroid synthesis and cardiovascular effects. CONCLUSION: The very prominent effect on stress-induced corticosterone secretion of the genomic locus on chromosome 3 and its involvement in epistasis highlights the critical role of this specific locus in the regulation of the HPA axis.

The (15)N isotope effect as a means for correlating phenotypic alterations and affected pathways in a trait anxiety mouse model.

Stable isotope labeling techniques hold great potential for accurate quantitative proteomics comparisons by MS. To investigate the effect of stable isotopes in vivo, we metabolically labeled high anxiety-related behavior (HAB) mice with the heavy nitrogen isotope (15)N. (15)N-labeled HAB mice exhibited behavioral alterations compared to unlabeled ((14)N) HAB mice in their depression-like phenotype. To correlate behavioral alterations with changes on the molecular level, we explored the (15)N isotope effect on the brain proteome by comparing protein expression levels between (15)N-labeled and (14)N HAB mouse brains using quantitative MS. By implementing two complementary in silico pathway analysis approaches, we were able to identify altered networks in (15)N-labeled HAB mice, including major metabolic pathways such as the tricarboxylic acid (TCA) cycle and oxidative phosphorylation. Here, we discuss the affected pathways with regard to their relevance for the behavioral phenotype and critically assess the utility of exploiting the (15)N isotope effect for correlating phenotypic and molecular alterations.

fMRI fingerprint of unconditioned fear-like behavior in rats exposed to trimethylthiazoline.

Unconditioned fear plays an important yet poorly understood role in anxiety disorders, and only few neuroimaging studies have focused on evaluating the underlying neuronal mechanisms. In rodents the predator odor trimethylthiazoline (TMT), a synthetic component of fox feces, is commonly used to induce states of unconditioned fear. In this study, arterial spin labeling-based functional magnetic resonance imaging (fMRI) was applied to detect TMT-induced regional modulations of neuronal activity in Wistar rats. During TMT exposure the rats displayed increased freezing behavior and reduced exploration in the odor-associated area. Neuronal activity was selectively increased in the dorsal periaqueductal gray, superior colliculus and medial thalamus and reduced in the median raphe, locus coeruleus, nucleus accumbens shell, ventral tegmental area, ventral pallidum and entorhinal piriform cortex. This fMRI fingerprint involving distinct neuronal pathways was used to describe a schematic model of fear processing. Key brain areas known to underlie fear and anxiety-related autonomic and behavioral responses as well as centers of motivational processing were identified as being part of this functional circuitry of innate fear. Thus, preclinical fMRI studies based on unconditioned fear methods may provide a valuable translational approach to better characterize etiological and pathological processes underlying anxiety disorders.

Imaging trait anxiety in high anxiety F344 rats: Focus on the dorsomedial prefrontal cortex.

Functional magnetic resonance imaging (fMRI) has become an important method in clinical psychiatry research whereas there are still only few comparable preclinical investigations. Herein, we report that fMRI in rats can provide key information regarding brain areas underlying anxiety behavior. Perfusion as surrogate for neuronal activity was measured by means of arterial spin labeling-based fMRI in various brain areas of high anxiety F344 rats and control Sprague-Dawley rats. In one of these areas, the dorsomedial prefrontal cortex (dmPFC), c-Fos labeling was compared between these two strains with immunolabeling. The effects of a neurotoxic ibotenic acid lesion of the dmPFC in F344 rats were examined in a social approach-avoidance anxiety procedure and fMRI. Regional brain activity of high anxiety F344 rats was different in selective cortical and subcortical areas as compared to that of low anxiety Sprague-Dawley rats; the largest difference (i.e. hyperactivity) was measured in the dmPFC. Independently, c-Fos labeling confirmed that F344 rats show increased dmPFC activity. The functional role was confirmed by neurotoxic lesion of the dmPFC that reversed the high anxiety-like behavior and partially normalized the brain activity pattern of F344 rats. The current findings may have translational value as increased activity is reported in an equivalent cortical area in patients with social anxiety, suggesting that pharmacological or functional inhibition of activity in this brain area should be explored to alleviate social anxiety in patients.

Proteomic and metabolomic profiling of a trait anxiety mouse model implicate affected pathways.

Depression and anxiety disorders affect a great number of people worldwide. Whereas singular factors have been associated with the pathogenesis of psychiatric disorders, growing evidence emphasizes the significance of dysfunctional neural circuits and signaling pathways. Hence, a systems biology approach is required to get a better understanding of psychiatric phenotypes such as depression and anxiety. Furthermore, the availability of biomarkers for these disorders is critical for improved diagnosis and monitoring treatment response. In the present study, a mouse model presenting with robust high versus low anxiety phenotypes was subjected to thorough molecular biomarker and pathway discovery analyses. Reference animals were metabolically labeled with the stable (15)N isotope allowing an accurate comparison of protein expression levels between the high anxiety-related behavior versus low anxiety-related behavior mouse lines using quantitative mass spectrometry. Plasma metabolomic analyses identified a number of small molecule biomarkers characteristic for the anxiety phenotype with particular focus on myo-inositol and glutamate as well as the intermediates involved in the tricarboxylic acid cycle. In silico analyses suggested pathways and subnetworks as relevant for the anxiety phenotype. Our data demonstrate that the high anxiety-related behavior and low anxiety-related behavior mouse model is a valuable tool for anxiety disorder drug discovery efforts.

Proteomics and metabolomics analysis of a trait anxiety mouse model reveals divergent mitochondrial pathways.

BACKGROUND: Although anxiety disorders are the most prevalent psychiatric disorders, no molecular biomarkers exist for their premorbid diagnosis, accurate patient subcategorization, or treatment efficacy prediction. To unravel the neurobiological underpinnings and identify candidate biomarkers and affected pathways for anxiety disorders, we interrogated the mouse model of high anxiety-related behavior (HAB), normal anxiety-related behavior (NAB), and low anxiety-related behavior (LAB) employing a quantitative proteomics and metabolomics discovery approach. METHODS: We compared the cingulate cortex synaptosome proteomes of HAB and LAB mice by in vivo (15)N metabolic labeling and mass spectrometry and quantified the cingulate cortex metabolomes of HAB/NAB/LAB mice. The combined data sets were used to identify divergent protein and metabolite networks by in silico pathway analysis. Selected differentially expressed proteins and affected pathways were validated with immunochemical and enzymatic assays. RESULTS: Altered levels of up to 300 proteins and metabolites were found between HAB and LAB mice. Our data reveal alterations in energy metabolism, mitochondrial import and transport, oxidative stress, and neurotransmission, implicating a previously nonhighlighted role of mitochondria in modulating anxiety-related behavior. CONCLUSIONS: Our results offer insights toward a molecular network of anxiety pathophysiology with a focus on mitochondrial contribution and provide the basis for pinpointing affected pathways in anxiety-related behavior.

Maternal care differs in mice bred for high vs. low trait anxiety: impact of brain vasopressin and cross-fostering.

Brain arginine vasopressin (AVP) not only regulates male social behavior and emotionality, but also promotes maternal behavior, as has been shown in rats. In our CD1 mice breed for high (HAB) or low (LAB) anxiety-related behavior, LAB mice have markedly less AVP mRNA expression in the hypothalamic paraventricular nucleus compared with HAB mice. Together these findings suggest that HAB and LAB mice represent a good model to assess the role of AVP in mouse maternal behavior. Therefore, we studied maternal care of HAB and LAB mouse dams and investigated the impact of maternal care on the offspring's anxiety in a cross-fostering paradigm. In comparison with HAB dams, LABs displayed less maternal care. Daily acute intracerebroventricular infusions of AVP in early lactation increased maternal care of LAB dams and acted anxiogenically. Cross-fostering on postnatal day 5 did not alter separation-induced high and low ultrasonic vocalization calling frequency, a measure of inborn anxiety, in HAB and LAB offspring, respectively. However, adult cross-fostered HAB mice displayed a trend towards decreased anxiety on the elevated plus-maze, which was still significantly higher compared with LAB mice. The low levels of depressive-like behavior, stress-reactivity, and hypothalamic AVP mRNA expression in adult LAB offspring were found to be independent of cross-fostering. In conclusion, the HAB/LAB differences in maternal care and anxiety are robust and strongly depend on differences in the AVP system. The seemingly rigid genetic predisposition to hyperanxiety can only be moderately attenuated by the received nurturing.

Stable isotope metabolic labeling with a novel N-enriched bacteria diet for improved proteomic analyses of mouse models for psychopathologies.

The identification of differentially regulated proteins in animal models of psychiatric diseases is essential for a comprehensive analysis of associated psychopathological processes. Mass spectrometry is the most relevant method for analyzing differences in protein expression of tissue and body fluid proteomes. However, standardization of sample handling and sample-to-sample variability are problematic. Stable isotope metabolic labeling of a proteome represents the gold standard for quantitative mass spectrometry analysis. The simultaneous processing of a mixture of labeled and unlabeled samples allows a sensitive and accurate comparative analysis between the respective proteomes. Here, we describe a cost-effective feeding protocol based on a newly developed (15)N bacteria diet based on Ralstonia eutropha protein, which was applied to a mouse model for trait anxiety. Tissue from (15)N-labeled vs. (14)N-unlabeled mice was examined by mass spectrometry and differences in the expression of glyoxalase-1 (GLO1) and histidine triad nucleotide binding protein 2 (Hint2) proteins were correlated with the animals' psychopathological behaviors for methodological validation and proof of concept, respectively. Additionally, phenotyping unraveled an antidepressant-like effect of the incorporation of the stable isotope (15)N into the proteome of highly anxious mice. This novel phenomenon is of considerable relevance to the metabolic labeling method and could provide an opportunity for the discovery of candidate proteins involved in depression-like behavior. The newly developed (15)N bacteria diet provides researchers a novel tool to discover disease-relevant protein expression differences in mouse models using quantitative mass spectrometry.

A hypomorphic vasopressin allele prevents anxiety-related behavior.

BACKGROUND: To investigate neurobiological correlates of trait anxiety, CD1 mice were selectively bred for extremes in anxiety-related behavior, with high (HAB) and low (LAB) anxiety-related behavior mice additionally differing in behavioral tests reflecting depression-like behavior. METHODOLOGY/ PRINCIPAL FINDINGS: In this study, microarray analysis, in situ hybridization, quantitative real-time PCR and immunohistochemistry revealed decreased expression of the vasopressin gene (Avp) in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei of adult LAB mice compared to HAB, NAB (normal anxiety-related behavior) and HABxLAB F1 intercross controls, without detecting differences in receptor expression or density. By sequencing the regions 2.5 kbp up- and downstream of the Avp gene locus, we could identify several polymorphic loci, differing between the HAB and LAB lines. In the gene promoter, a deletion of twelve bp Delta(-2180-2191) is particularly likely to contribute to the reduced Avp expression detected in LAB animals under basal conditions. Indeed, allele-specific transcription analysis of F1 animals revealed a hypomorphic LAB-specific Avp allele with a reduced transcription rate by 75% compared to the HAB-specific allele, thus explaining line-specific Avp expression profiles and phenotypic features. Accordingly, intra-PVN Avp mRNA levels were found to correlate with anxiety-related and depression-like behaviors. In addition to this correlative evidence, a significant, though moderate, genotype/phenotype association was demonstrated in 258 male mice of a freely-segregating F2 panel, suggesting a causal contribution of the Avp promoter deletion to anxiety-related behavior. DISCUSSION: Thus, the identification of polymorphisms in the Avp gene promoter explains gene expression differences in association with the observed phenotype, thus further strengthening the concept of the critical involvement of centrally released AVP in trait anxiety.

Diabetes insipidus and, partially, low anxiety-related behaviour are linked to a SNP-associated vasopressin deficit in LAB mice.

Following secretion from the posterior pituitary, the neuropeptide vasopressin (AVP) stimulates the kidney to retain water, and when released centrally it can contribute to anxiety- and depression-like behaviours. We hypothesized that CD1 mice bred for low trait anxiety (LAB) suffer from a deficit in AVP. Both osmotically stimulated peripheral secretion and intra-paraventricular nucleus (PVN) release of AVP were found decreased in LAB animals compared with normal anxiety (NAB) or high anxiety (HAB) controls. Consequently, in addition to their extreme non-anxiety, LAB mice showed signs of central diabetes insipidus (cDI), including increased fluid intake and reduced urine osmolality, as well as a pathological increase in plasma osmolality upon water deprivation. These cDI symptoms were attenuated by administration of a selective AVP V2 receptor agonist. A single nucleotide polymorphism (SNP) in exon 1 (C(+40)T) of the Avp gene of LAB animals causes an amino acid substitution in the signal peptide of the AVP precursor, and is likely to impair processing and trafficking of the precursor, as suggested by reduced axonal transport of AVP from the hypothalamic PVN, finally contributing to cDI symptoms and low trait anxiety. In an F2 panel, this SNP co-segregated with fluid intake and showed a partial contribution to low anxiety-related behaviour, indicated by its co-segregation with time spent on the open arms of the elevated plus-maze in a subset of F2 mice. Thus, the SNP-associated deficit in plasma and central AVP contributes to signs of cDI and, at least partially, to low trait anxiety, both features being typical of LAB animals.

Candidate genes of anxiety-related behavior in HAB/LAB rats and mice: focus on vasopressin and glyoxalase-I.

Two animal models of trait anxiety, HAB/LAB rats and mice, are described, representing inborn extremes in anxiety-related behavior. The comprehensive phenotypical characterization included basal behavioral features, stress-coping strategies and neuroendocrine responses upon stressor exposure with HAB animals being hyper-anxious, preferring passive coping, emitting more stressor-induced ultrasonic vocalization calls and showing typical peculiarities of the hypothalamic-pituitary-adrenocortical axis and line-specific patterns of Fos expression in the brain indicative of differential neuronal activation. In most cases, unselected Wistar rats and CD1 mice, respectively, displayed intermediate behaviors. In both HAB/LAB rats and mice, the behavioral phenotype has been found to be significantly correlated with the expression of the neuropeptide arginine vasopressin (AVP) at the level of the hypothalamic paraventricular nucleus (PVN). Additional receptor antagonist approaches in HABs confirmed that intra-PVN release of AVP is likely to contribute to hyper-anxiety and depression-like behavior. As shown exemplarily in HAB rats and LAB mice, single nucleotide polymorphisms (SNPs) in regulatory structures of the AVP gene underlie AVP-mediated phenotypic phenomena; in HAB rats, a SNP in the promoter of the AVP gene leads to reduced binding of the transcriptional repressor CBF-A, thus causing AVP overexpression and overrelease. Conversely, in LAB mice, a SNP in the AVP gene seems to cause an amino acid exchange in the signal peptide, presumably leading to a deficit in bioavailable AVP likely to underlie the total hypo-anxiety of LAB mice in combination with signs of central diabetes insipidus. Another feature of LAB mice is overexpression of glyoxalase-I. The functional characterization of this enzyme will determine its involvement in anxiety-related behavior beyond that of a reliable biomarker. The further identification of quantitative trait loci, candidate genes (and their products) and SNPs will not only help to explain inter-individual variation in emotional behavior, but will also reveal novel targets for anxiolytic and antidepressive interventions.