Hostility in medication-resistant major depression and comorbid generalized anxiety disorder is related to increased hippocampal-amygdala 5-HT2A receptor density.

Major depressive disorder (MDD) and generalized anxiety disorder (GAD) are severe and difficult-to-treat psychiatric illnesses with high rates of comorbidity. Although both disorders are treated with serotonergic based psychotropic agents, little is known on the influence of the serotonergic neurotransmitter system on the occurrence of comorbid GAD when clinically depressed. To investigate this poorly understood clinical question, we examined the involvement of frontolimbic post-synaptic 5-HT2A receptors in 20 medication-resistant depressed (MRD) patients with half of them diagnosed with comorbid GAD with 123I-5-I-R91150 SPECT. To explore whether 5-HT2A receptor-binding indices (BI) associated with comorbid GAD could be related to distinct psychopathological symptoms, all were assessed with the symptom Checklist-90-Revised (SCL-90-R). MRD patients with comorbid GAD displayed significantly higher 5-HT2A receptor BI in the hippocampal-amygdala complex, compared to MRD patients without GAD. Correlation analyses revealed that the 5-HT2A receptor BI in these areas were significantly related to the SCL-90-R subscale hostility (HOS), especially for those MRD patients with comorbid GAD. Comorbid MRD-GAD may be characterized with increased hippocampal-amygdala 5-HT2A receptor BI which could represent enhanced levels in hostility in such kinds of patients. Adapted psychotherapeutic interventions may be warranted.

Kinetic analysis of [18F] altanserin bolus injection in the canine brain using PET imaging.

BACKGROUND: Currently, [18F] altanserin is the most frequently used PET-radioligand for serotonin2A (5-HT2A) receptor imaging in the human brain but has never been validated in dogs. In vivo imaging of this receptor in the canine brain could improve diagnosis and therapy of several behavioural disorders in dogs. Furthermore, since dogs are considered as a valuable animal model for human psychiatric disorders, the ability to image this receptor in dogs could help to increase our understanding of the pathophysiology of these diseases. Therefore, five healthy laboratory beagles underwent a 90-min dynamic PET scan with arterial blood sampling after [18F] altanserin bolus injection. Compartmental modelling using metabolite corrected arterial input functions was compared with reference tissue modelling with the cerebellum as reference region. RESULTS: The distribution of [18F] altanserin in the canine brain corresponded well to the distribution of 5-HT2A receptors in human and rodent studies. The kinetics could be best described by a 2-Tissue compartment (2-TC) model. All reference tissue models were highly correlated with the 2-TC model, indicating compartmental modelling can be replaced by reference tissue models to avoid arterial blood sampling. CONCLUSIONS: This study demonstrates that [18F] altanserin PET is a reliable tool to visualize and quantify the 5-HT2A receptor in the canine brain.

Regional alterations of cerebral [18F]FDG metabolism in the chronic unpredictable mild stress- and the repeated corticosterone depression model in rats.

Preclinical research has been indispensable in the exploration of the neurological basis of major depressive disorder (MDD). The present study aimed to examine effects on regional brain activity of two frequently used depression models, the chronic unpredictable mild stress (CUMS)- and the chronic corticosterone (CORT) depression model. The CUMS and CORT depression model were induced by exposing male Long-Evans rats to a 4-week procedure of unpredictable mild stressors or a 3-week procedure of chronic corticosterone, respectively. Positron emission tomography with [18F]FDG was performed to determine alterations in regional brain activity. In addition, depressive- and anxiety-like behaviour was assessed via the forced swim test and the open field test, respectively. The chronic CORT administration, but not the CUMS model, significantly induced depressive-like behaviour and elevated plasma corticosterone levels. Compared to control, induction of the CORT depression model resulted in a significantly reduced glucose consumption in the insular cortex and the striatum, and a significantly elevated consumption in the cerebellum and the midbrain. Induction of the CUMS model replicated the findings with respect to the activity in the striatum region, and cerebellum, but missed significance in the insular cortex and the midbrain. Based on the alterations in behaviour and regional [18F]FDG uptake, a superior face validity and construct validity can be observed after induction of depression via chronic CORT injections, compared to the used CUMS paradigm.

Generation of functional thyroid from embryonic stem cells.

The primary function of the thyroid gland is to metabolize iodide by synthesizing thyroid hormones, which are critical regulators of growth, development and metabolism in almost all tissues. So far, research on thyroid morphogenesis has been missing an efficient stem-cell model system that allows for the in vitro recapitulation of the molecular and morphogenic events regulating thyroid follicular-cell differentiation and subsequent assembly into functional thyroid follicles. Here we report that a transient overexpression of the transcription factors NKX2-1 and PAX8 is sufficient to direct mouse embryonic stem-cell differentiation into thyroid follicular cells that organize into three-dimensional follicular structures when treated with thyrotropin. These in vitro-derived follicles showed appreciable iodide organification activity. Importantly, when grafted in vivo into athyroid mice, these follicles rescued thyroid hormone plasma levels and promoted subsequent symptomatic recovery. Thus, mouse embryonic stem cells can be induced to differentiate into thyroid follicular cells in vitro and generate functional thyroid tissue.

Mucosal and blood-brain barrier transport kinetics of the plant N-alkylamide spilanthol using in vitro and in vivo models.

BACKGROUND: N-alkylamides (NAAs) are a large group of secondary metabolites occurring in more than 25 plant families which are often used in traditional medicine. A prominent active NAA is spilanthol. The general goal was to quantitatively investigate the gut mucosa and blood-brain barrier (BBB) permeability pharmacokinetic properties of spilanthol. METHODS: Spilanthes acmella (L.) L. extracts, as well as purified spilanthol were used to investigate (1) the permeation of spilanthol through a Caco-2 cell monolayer in vitro, (2) the absorption from the intestinal lumen after oral administration to rats, and (3) the permeation through the BBB in mice after intravenous injection. Quantification of spilanthol was performed using a validated bio-analytical UPLC-MS(2) method. RESULTS: Spilanthol was able to cross the Caco-2 cell monolayer in vitro from the apical-to-basolateral side and from the basolateral-to-apical side with apparent permeability coefficients Papp between 5.2 · 10(-5) and 10.2 · 10(-5) cm/h. This in vitro permeability was confirmed by the in vivo intestinal absorption in rats after oral administration, where an elimination rate constant ke of 0.6 h(-1) was obtained. Furthermore, once present in the systemic circulation, spilanthol rapidly penetrated the blood-brain barrier: a highly significant influx of spilanthol into the brains was observed with a unidirectional influx rate constant K1 of 796 µl/(g · min). CONCLUSIONS: Spilanthol shows a high intestinal absorption from the gut into the systemic circulation, as well as a high BBB permeation rate from the blood into the brain.

In vivo quantification of the [(11)C]DASB binding in the normal canine brain using positron emission tomography.

BACKGROUND: [(11)C]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile ([(11)C]DASB) is currently the mostly used radiotracer for positron emission tomography (PET) quantitative studies of the serotonin transporter (SERT) in the human brain but has never been validated in dogs. The first objective was therefore to evaluate normal [(11)C]DASB distribution in different brain regions of healthy dogs using PET. The second objective was to provide less invasive and more convenient alternative methods to the arterial sampling-based kinetic analysis. RESULTS: A dynamic acquisition of the brain was performed during 90 min. The PET images were coregistered with the magnetic resonance images taken prior to the study in order to manually drawn 20 regions of interest (ROIs). The highest radioactivity concentration of [(11)C]DASB was observed in the hypothalamus, raphe nuclei and thalamus and lowest levels in the parietal cortex, occipital cortex and cerebellum. The regional radioactivity in those 20 ROIs was quantified using the multilinear reference tissue model 2 (MRTM2) and a semi-quantitative method. The values showed least variability between 40 and 60 min and this time interval was set as the optimal time interval for [(11)C]DASB quantification in the canine brain. The correlation (R(2)) between the MRTM2 and the semi-quantitative method using the data between 40 and 60 min was 99.3% (two-tailed p-value < 0.01). CONCLUSIONS: The reference tissue models and semi-quantitative method provide a more convenient alternative to invasive arterial sampling models in the evaluation of the SERT of the normal canine brain. The optimal time interval for static scanning is set at 40 to 60 min after tracer injection.

Effect of recombinant human thyroid stimulating hormone on radioactive iodine uptake by thyroid carcinoma in dogs.

BACKGROUND: The high doses of radioiodine-131 (131I) and, subsequently, the high radioactive burden for dog and environment warrants optimization of 131I therapy in dogs with thyroid carcinoma (TC). HYPOTHESIS/OBJECTIVES: To evaluate the effect of a revised protocol with recombinant human thyroid stimulating hormone (rhTSH) on tumor radioactive iodine uptake (RAIU) in dogs with TC. ANIMALS: Nine client-owned dogs diagnosed with TC. METHODS: A prospective cross-over study in which tumor RAIU was calculated and compared at 8 hours (8h-RAIU) and 24 hours (24h-RAIU) after injection of radioactive iodine-123 (123I), once with and once without rhTSH (ie, 250 µg, IM, 24 and 12 hours before 123I) in each dog. Simultaneously, serum total thyroxine (TT4) and TSH were measured at baseline (T0), and 6 (T6), 12 (T12), 24 (T24), and 48 hours (T48) after the first rhTSH administration. RESULTS: Tumor RAIU was significantly higher at 24 hours with rhTSH compared to no rhTSH (mean difference = 8.85%, 95% CI of [1.56; 16.14]; P = .03), while this was non-significant at 8 hours (mean difference = 4.54%, 95% CI of [0.35; 8.73]; P = .05). A significant change of serum TT4 (median difference T24 - T0 = 35.86 nmol/L, interquartile range [IQR] = 15.74 nmol/L) and TSH (median difference T24 - T0 = 1.20 ng/mL, IQR = 1.55 ng/mL) concentrations occurred after administration of rhTSH (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE: Recombinant human TSH could optimize 131I treatment in dogs with TC by increasing tumor RAIU and thus 131I treatment efficacy.

A rapid stability-indicating, fused-core HPLC method for simultaneous determination of ß-artemether and lumefantrine in anti-malarial fixed dose combination products.

BACKGROUND: Artemisinin-based fixed dose combination (FDC) products are recommended by World Health Organization (WHO) as a first-line treatment. However, the current artemisinin FDC products, such as ß-artemether and lumefantrine, are inherently unstable and require controlled distribution and storage conditions, which are not always available in resource-limited settings. Moreover, quality control is hampered by lack of suitable analytical methods. Thus, there is a need for a rapid and simple, but stability-indicating method for the simultaneous assay of ß-artemether and lumefantrine FDC products. METHODS: Three reversed-phase fused-core HPLC columns (Halo RP-Amide, Halo C18 and Halo Phenyl-hexyl), all thermostated at 30°C, were evaluated. ß-Artemether and lumefantrine (unstressed and stressed), and reference-related impurities were injected and chromatographic parameters were assessed. Optimal chromatographic parameters were obtained using Halo RP-Amide column and an isocratic mobile phase composed of acetonitrile and 1 mM phosphate buffer pH 3.0 (52:48; V/V) at a flow of 1.0 ml/min and 3 µl injection volume. Quantification was performed at 210 nm and 335 nm for ß-artemether and for lumefantrine, respectively. In-silico toxicological evaluation of the related impurities was made using Derek Nexus v2.0®. RESULTS: Both ß-artemether and lumefantrine were separated from each other as well as from the specified and unspecified related impurities including degradants. A complete chromatographic run only took four minutes. Evaluation of the method, including a Plackett-Burman robustness verification within analytical QbD-principles, and real-life samples showed the method is suitable for quantitative assay purposes of both active pharmaceutical ingredients, with a mean recovery relative standard deviation (± RSD) of 99.7 % (± 0.7%) for ß-artemether and 99.7 % (± 0.6%) for lumefantrine. All identified ß-artemether-related impurities were predicted in Derek Nexus v2.0® to have toxicity risks similar to ß-artemether active pharmaceutical ingredient (API) itself. CONCLUSIONS: A rapid, robust, precise and accurate stability-indicating, quantitative fused-core isocratic HPLC method was developed for simultaneous assay of ß-artemether and lumefantrine. This method can be applied in the routine regulatory quality control of FDC products. The in-silico toxicological investigation using Derek Nexus® indicated that the overall toxicity risk for ß-artemether-related impurities is comparable to that of ß-artemether API.

Normal regional distribution of cerebral blood flow in dogs: comparison between (99m) Tc-ethylcysteinate dimer and (99m) Tc- hexamethylpropylene amine oxime single photon emission computed tomography.

Functional imaging provides important insights into canine brain pathologies such as behavioral problems. Two (99m) Tc-labeled single photon emission computed tomography (SPECT) cerebral blood flow tracers-ethylcysteinate dimer (ECD) and hexamethylpropylene amine oxime (HMPAO)-are commonly used in human medicine and have been used previously in dogs but intrasubject comparison of both tracers in dogs is lacking. Therefore, this study investigated whether regional distribution differences between both tracers occur in dogs as is reported in humans. Eight beagles underwent two SPECT examinations first with (99m) Tc-ECD and followed by (99m) Tc-HMPAO. SPECT scanning was performed with a triple head gamma camera equipped with ultrahigh resolution parallel hole collimators. Images were reconstructed using filtered backprojection with a Butterworth filter. Emission data were fitted to a template permitting semiquantification using predefined regions or volumes of interest (VOIs). For each VOI, perfusion indices were calculated by normalizing the regional counts per voxel to total brain counts per voxel. The obtained perfusion indices for each region for both tracers were compared with a paired Student's T-test. Significant (P < 0.05) regional differences were seen in the subcortical region and the cerebellum. Both tracers can be used to visualize regional cerebral blood flow in dogs, however, due to the observed regional differences, they are not entirely interchangeable.

Regional cerebral blood flow in dogs with congenital extrahepatic portosystemic shunts before surgery and six months after successful closure.

Previous studies both in humans and dogs with chronic liver diseases have shown that regional cerebral brain flow (rCBF) is altered. The current study aimed to assess abnormalities in rCBF in dogs with congenital extrahepatic portosystemic shunts (cEHPSS), both at diagnosis and after successful surgical attenuation. Furthermore, the influence of age at diagnosis, severity of hepatic encephalopathy (HE) and type of cEHPSS on rCBF were explored as a base for future research. Single photon emission computed tomography (SPECT) with 99mtechnetium-hexamethylpropylene amine oxime tracer was performed before surgical attenuation and six months postoperatively. Twenty-four dogs with cEHPSS had SPECT at time of diagnosis and 13 dogs with a confirmed closed cEHPSS had a second SPECT six months postoperatively. At diagnosis, dogs with cEHPSS had an altered rCBF distribution compared to healthy dogs. This altered rCBF distribution seemed to be most apparent in dogs ≥ one year and in dogs with overt HE at diagnosis. Six months postoperatively, only the rCBF distribution in the subcortical region decreased compared to pre-operatively. In conclusion, all dogs with cEHPSS had altered rCBF which did not seem to normalize completely six months after successful surgical attenuation. Dogs diagnosed at an older age seemed to have more distinct abnormalities in rCBF compared to younger dogs.

Radioiodine treatment in hyperthyroid cats: insights into the characteristics of owners and their cats, and owner motivation and perceptions.

OBJECTIVES: Radioiodine (131I) therapy is the most appropriate treatment option for many hyperthyroid cats, as it is minimally invasive and often curative. Nevertheless, 131I treatment is not always pursued by owners. Hence, it is important to obtain more insight into owner satisfaction during and after 131I treatment, and their decision-making process. In this study, we describe the characteristics of owners and their hyperthyroid cats referred for 131I therapy, and determine owners' motivation and how they experienced the 131I treatment of their cat. METHODS: A survey was sent to owners whose cats underwent 131I therapy (n = 1071) between 2010 and 2017 at Ghent University. The survey contained 35 questions with tick-box or free-text answer options concerning family situation, pet insurance, previous therapy, comorbidities, motivation for 131I therapy and owner perception of this treatment. RESULTS: In total, 438 owners completed 94% or more of the questionnaire. Over half of the cats (55%) had received previous medical, dietary or surgical treatment. Motivations for changing the initial therapy to 131I therapy included difficulties in administering medication (31%), insufficient improvement in clinical signs (23%), side effects (16%) and following the referring veterinarian's advice (16%). Almost a fifth of owners (18%) were not informed about the existence of 131I therapy by their veterinarian and found information on 131I treatment online or through friends. Hospitalising their cat was very distressing for 17% of owners. Most owners (92%) were satisfied with the treatment. Reasons for dissatisfaction were insufficient communication, iatrogenic hypothyroidism, persistent hyperthyroidism and comorbidities post-treatment. CONCLUSIONS AND RELEVANCE: Our study stresses the importance of communication regarding the possible outcome of 131I treatment, the importance of managing underlying comorbidities before treatment and anticipating the stress of owners during their cat's hospitalisation period. The results of this study could help in improving client communication when advising on 131I treatment.

Network analysis reveals abnormal functional brain circuitry in anxious dogs.

Anxiety is a common disease within human psychiatric disorders and has also been described as a frequently neuropsychiatric problem in dogs. Human neuroimaging studies showed abnormal functional brain networks might be involved in anxiety. In this study, we expected similar changes in network topology are also present in dogs. We performed resting-state functional MRI on 25 healthy dogs and 13 patients. The generic Canine Behavioral Assessment & Research Questionnaire was used to evaluate anxiety symptoms. We constructed functional brain networks and used graph theory to compare the differences between two groups. No significant differences in global network topology were found. However, focusing on the anxiety circuit, global efficiency and local efficiency were significantly higher, and characteristic path length was significantly lower in the amygdala in patients. We detected higher connectivity between amygdala-hippocampus, amygdala-mesencephalon, amygdala-thalamus, frontal lobe-hippocampus, frontal lobe-thalamus, and hippocampus-thalamus, all part of the anxiety circuit. Moreover, correlations between network metrics and anxiety symptoms were significant. Altered network measures in the amygdala were correlated with stranger-directed fear and excitability; altered degree in the hippocampus was related to attachment/attention seeking, trainability, and touch sensitivity; abnormal frontal lobe function was related to chasing and familiar dog aggression; attachment/attention seeking was correlated with functional connectivity between amygdala-hippocampus and amygdala-thalamus; familiar dog aggression was related to global network topology change. These findings may shed light on the aberrant topological organization of functional brain networks underlying anxiety in dogs.

Structural connectome alterations in anxious dogs: a DTI-based study.

Anxiety and fear are dysfunctional behaviors commonly observed in domesticated dogs. Although dogs and humans share psychopathological similarities, little is known about how dysfunctional fear behaviors are represented in brain networks in dogs diagnosed with anxiety disorders. A combination of diffusion tensor imaging (DTI) and graph theory was used to investigate the underlying structural connections of dysfunctional anxiety in anxious dogs and compared with healthy dogs with normal behavior. The degree of anxiety was assessed using the Canine Behavioral Assessment & Research Questionnaire (C-BARQ), a widely used, validated questionnaire for abnormal behaviors in dogs. Anxious dogs showed significantly decreased clustering coefficient ([Formula: see text]), decreased global efficiency ([Formula: see text]), and increased small-worldness (σ) when compared with healthy dogs. The nodal parameters that differed between the anxious dogs and healthy dogs were mainly located in the posterior part of the brain, including the occipital lobe, posterior cingulate gyrus, hippocampus, mesencephalon, and cerebellum. Furthermore, the nodal degree ([Formula: see text]) of the left cerebellum was significantly negatively correlated with "excitability" in the C-BARQ of anxious dogs. These findings could contribute to the understanding of a disrupted brain structural connectome underlying the pathological mechanisms of anxiety-related disorders in dogs.

Accelerated high frequency rTMS induces time-dependent dopaminergic alterations: a DaTSCAN brain imaging study in healthy beagle dogs.

Aim: The neurobiological effects of repetitive transcranial magnetic stimulation are believed to run in part through the dopaminergic system. Accelerated high frequency rTMS (aHF-rTMS), a new form of stimuli delivery, is currently being tested for its usefulness in treating human and canine mental disorders. However, the short-and long-term neurobiological effects are still unclear, including the effects on the dopaminergic system. In aHF-rTMS, multiple sessions are delivered within 1 day instead of one session per day, not only to accelerate the time to response but also to increase clinical efficacy. To gain more insight into the neurobiology of aHF-rTMS, we investigated whether applying five sessions in 1 day has direct and/or delayed effects on the dopamine transporter (DAT), and on dopamine metabolites of cerebrospinal fluid (CSF) in beagles. Materials and methods: Thirteen beagles were randomly divided into two groups: five active stimulation sessions (n = 9), and 5 sham stimulation sessions (n = 4). Using DaTSCAN, DAT binding indices (BI) were obtained at baseline, after 1 day, 1 month, and 3 months post stimulation. CSF samples were collected after each scan. Results: Active aHF-rTMS significantly reduced striatal DAT BI 1 day post-active stimulation session (p < 0.01), and the effect lasted to 1 month (p < 0.01). No significant DAT BI change was found in sham group. No significant changes in dopamine metabolites of CSF were found. Conclusion: Although no significant effects on CSF dopamine metabolites were observed, five sessions of active aHF-rTMS significantly decreased striatal DAT BI after 1 day and up to 1 month post stimulation, indicating immediate and delayed effects on the brain dopaminergic system. Our findings in healthy beagles further substantiate the assumption that (a)HF-rTMS affects the brain dopaminergic system and it may pave the way to apply (a)HF-rTMS treatment in behaviorally disturbed dogs.

Low-dose xenogeneic mesenchymal stem cells target canine osteoarthritis through systemic immunomodulation and homing.

BACKGROUND: As current therapies for canine osteoarthritis (OA) provide mainly symptomatic improvement and fail to address the complex pathology of the disease, mesenchymal stem cells (MSCs) offer a promising biological approach to address both aspects of OA through their immunomodulatory properties. METHODS: This study aimed to investigate the safety and efficacy of xenogeneic MSCs in dogs with OA at different dose levels after intravenous injection. OA was surgically induced in the right stifle joint. Thirty-two male and female dogs were divided into three treatment groups and a control group. Regular general physical examinations; lameness, joint, radiographic, and animal caretaker assessments; pressure plate analyses; and blood analyses were performed over 42 days. At study end, joint tissues were evaluated regarding gross pathology, histopathology, and immunohistochemistry. In a follow-up study, the biodistribution of intravenously injected 99mTc-labeled equine peripheral blood-derived MSCs was evaluated over 24h in three dogs after the cruciate ligament section. RESULTS: The dose determination study showed the systemic administration of ePB-MSCs in a canine OA model resulted in an analgesic, anti-inflammatory, and joint tissue protective effect associated with improved clinical signs and improved cartilage structure, as well as a good safety profile. Furthermore, a clear dose effect was found with 0.3 × 106 ePB-MSCs as the most effective dose. In addition, this treatment was demonstrated to home specifically towards the injury zone in a biodistribution study. CONCLUSION: This model-based study is the first to confirm the efficacy and safety of systemically administered xenogeneic MSCs in dogs with OA. The systemic administration of a low dose of xenogeneic MSCs could offer a widely accessible, safe, and efficacious treatment to address the complex pathology of canine OA and potentially slow down the disease progression by its joint tissue protective effect.

Serotonin 2A receptor, serotonin transporter and dopamine transporter alterations in dogs with compulsive behaviour as a promising model for human obsessive-compulsive disorder.

Neuro-imaging studies have shown altered, yet often inconsistent, serotonergic and dopaminergic neurotransmission in patients with obsessive-compulsive disorder (OCD). We investigated both serotonergic and dopaminergic neurotransmission in 9 drug-naïve dogs with compulsive behaviour, as a potential model for human OCD. Single photon emission computed tomography was used with (123)I-R91150 and (123)I-FP-CIT, in combination with (99m)Tc-ECD brain perfusion co-registration, to measure the serotonin (5-HT) 2A receptor, dopamine transporter (DAT) and serotonin transporter (SERT) availability. Fifteen normally behaving dogs were used as reference group. Significantly lower 5-HT2A receptor radioligand availability in frontal and temporal cortices (bilateral) was observed. Further, in 78% of the compulsive dogs abnormal DAT ratios in left and right striatum were demonstrated. Interestingly, both increased and decreased DAT ratios were observed. Finally, significantly lower subcortical perfusion and (hypo)thalamic SERT availability were observed in the compulsive dogs. This study provides evidence for imbalanced serotonergic and dopaminergic pathways in the pathophysiology of compulsions in dogs. The similarities with the altered neurotransmission in human OCD provide construct validity for this non-induced, natural canine model, suggesting its usefulness for future investigations of the pathophysiology of human OCD as well as the effectiveness of psychopharmacological interventions.

Homing of radiolabelled xenogeneic equine peripheral blood-derived MSCs towards a joint lesion in a dog.

Osteoarthritis (OA) is a highly prevalent condition in dogs, causing a substantial reduction in quality of life and welfare of the animals. Current disease management focusses on pain relief but does not stop the progression of the disease. Therefore, mesenchymal stem cells (MSCs) could offer a promising disease modifying alternative. However, little is known about the behavior and the mode of action of MSCs following their administration. In the current case report, 99mTechnetium labelled xenogeneic equine peripheral blood-derived MSCs were intravenously injected in a 9 year old dog suffering from a natural occurring cranial cruciate ligament rupture. The biodistribution of the MSCs was evaluated during a 6-h follow-up period, using a full body scintigraphy imaging technique. No clinical abnormalities or ectopic tissue formations were detected throughout the study. A radiopharmaceutical uptake was present in the liver, heart, lung, spleen, kidneys and bladder of the dog. Furthermore, homing of the radiolabelled MSCs to the injured joint was observed, with 40.61 % higher uptake in the affected joint in comparison with the healthy contralateral joint. Finally, a local radioactive hotspot was seen at a part of the tail of the dog that had been injured recently. The current study is the first to confirm the homing of xenogeneic MSCs to a naturally occurring joint lesion after IV administration.

The Impact of Accelerated HF-rTMS on Canine Brain Metabolism: An [18F]-FDG PET Study in Healthy Beagles.

Background: Repetitive transcranial magnetic stimulation (rTMS) has been proven to be a useful tool for the treatment of several severe neuropsychiatric disorders. Accelerated (a)rTMS protocols may have the potential to result in faster clinical improvements, but the effects of such accelerated paradigms on brain function remain to be elucidated. Objectives: This sham-controlled arTMS study aimed to evaluate the immediate and delayed effects of accelerated high frequency rTMS (aHF-rTMS) on glucose metabolism in healthy beagle dogs when applied over the left frontal cortex. Methods: Twenty-four dogs were randomly divided into four unequal groups: five active (n = 8)/ sham (n = 4) stimulation sessions (five sessions in 1 day), 20 active (n = 8)/ sham (n = 4) stimulation sessions (five sessions/ day for 4 days), respectively. [18F] FDG PET scans were obtained at baseline, 24 h poststimulation, after 1 and 3 months post the last stimulation session. We explicitly focused on four predefined regions of interest (left/right prefrontal cortex and left/right hippocampus). Results: One day of active aHF-rTMS- and not sham- significantly increased glucose metabolism 24 h post-active stimulation in the left frontal cortex only. Four days of active aHF-rTMS only resulted in a nearly significant metabolic decrease in the left hippocampus after 1 month. Conclusions: Like in human psychiatric disorders, active aHF-rTMS in healthy beagles modifies glucose metabolism, although differently immediately or after 1 month post stimulation. aHF-rTMS may be also a valid option to treat mentally disordered dogs.

Accelerated HF-rTMS Modifies SERT Availability in the Subgenual Anterior Cingulate Cortex: A Canine [11C]DASB Study on the Serotonergic System.

Repetitive transcranial magnetic stimulation (rTMS) is thought to partly exert its antidepressant action through the serotonergic system. Accelerated rTMS may have the potential to result in similar but faster onset of clinical improvement compared to the classical daily rTMS protocols, but given that delayed clinical responses have been reported, the neurobiological effects of accelerated paradigms remain to be elucidated including on this neurotransmitter system. This sham-controlled study aimed to evaluate the effects of accelerated high frequency rTMS (aHF-rTMS) over the left frontal cortex on the serotonin transporter (SERT) in healthy beagle dogs. A total of twenty-two dogs were randomly divided into three unequal groups: five active stimulation sessions (five sessions in one day, n = 10), 20 active stimulation sessions (five sessions/day for four days, n = 8), and 20 sham stimulation sessions (five sessions/day for four days, n = 4). The SERT binding index (BI) was obtained at baseline, 24 h post stimulation protocol, one month, and three months post stimulation by a [11C]DASB PET scan. It was found that one day of active aHF-rTMS (five sessions) did not result in significant SERT BI changes at any time point. For the 20 sessions of active aHF-rTMS, one month after stimulation the SERT BI attenuated in the sgACC. No significant SERT BI changes were found after 20 sessions of sham aHF-rTMS. A total of four days of active aHF-rTMS modified sgACC SERT BI one month post-stimulation, explaining to some extent the delayed clinical effects of accelerated rTMS paradigms found in human psychopathologies.

Desirability function combining metabolic stability and functionality of peptides.

The evaluation of peptides as potential therapeutic or diagnostic agents requires the consideration of several criteria that are targeted around two axes: functionality and metabolic stability. Most often, a compromise has to be made between these mutually opposing characteristics. In this study, Derringer's desirability function, a multi-criteria decision-making method, was applied to determine the best peptide for opioid studies in a single figure-of-merit. The penetration of the blood-brain barrier (BBB) determines the biological functionality of neuropeptides in the brain target tissue, and consists of an influx and an efflux component. The metabolic stability in the two concerned tissues, i.e. plasma and brain, are taken into consideration as well. The overall selection of the peptide drug candidate having the highest BBB-drugability is difficult due to these conflicting responses as well as the different scalings of the four biological parameters under consideration. The highest desirability, representing the best BBB-drugability, was observed for dermorphin. This peptide is thus the most promising drug candidate from the set of eight opioid peptides that were investigated. The least desirable candidate, with the worst BBB influx and/or metabolic stability, was found to be CTAP. Validation of the desirability function by in vivo medical imaging showed that dermorphin and DAMGO penetrate the BBB, whereas EM-1 and TAPP did not. These results are thus consistent with those obtained with the desirability evaluation. To conclude, the multi-criteria decision method was proven to be useful in biomedical research, where a selection of the best candidate based on opposing characteristics is often required.