Feasibility of Magnetic Resonance Cholangiopancreatography in Dogs-A Post-Mortem Study.

Magnetic resonance cholangiopancreatography (MRCP) is commonly used in humans and is also feasible in cats. The aim of this post-mortem study was to investigate the feasibility of MRCP in eight adult dogs by comparing the visibility and measured diameters of the biliary tract and pancreatic ducts in MRCP with those of fluoroscopic retrograde cholangiopancreatography (FRCP) and corrosion casting. In autopsy, six dogs had no evidence of hepatobiliary disorders, one had pancreatic pathology, and one had biliary pathology. The gallbladder (GB), cystic duct, and common bile duct (CBD) were visible in the MRCP images of all eight dogs. However, the extrahepatic ducts and pancreatic ducts were only variably visible. There was statistical agreement between MRCP and FRCP in measuring the diameters of the GB (fundus and body) and CBD (at papilla and extrahepatic ducts' junction). The diameter measurements correlated between MRCP and corrosion casting. Our study showed that MRCP is feasible in dogs and allowed for proper visualization of the biliary tract. However, ducts with diameters of <1 mm were difficult to visualize using a 1.5 Tesla MRI machine. Further studies are warranted to apply MRCP in the diagnostic imaging of live dogs.

Cholangiopancreatography in cats: a post-mortem comparison of MRI with fluoroscopy, corrosion casting and histopathology.

In human medicine, magnetic resonance cholangiopancreatography (MRCP) is a valuable diagnostic tool for hepatobiliary and pancreatic diseases. In veterinary medicine, however, data evaluating the diagnostic value of MRCP are limited. The primary objectives of this prospective, observational, analytical investigation were to assess whether MRCP reliably visualizes the biliary tract and pancreatic ducts in cats without and with related disorders, and whether MRCP images and measurements of the ducts agree with those of fluoroscopic retrograde cholangiopancreatography (FRCP), corrosion casting and histopathology. A secondary objective was to provide MRCP reference diameters for bile ducts, GB, and pancreatic ducts. Donated bodies of 12 euthanized adult cats underwent MRCP, FRCP, and autopsy with corrosion casting of the biliary tract and pancreatic ducts using vinyl polysiloxane. Diameters of the biliary ducts, gallbladder (GB), and pancreatic ducts were measured using MRCP, FRCP, corrosion casts and histopathologic slides. There was an agreement between MRCP and FRCP in measuring diameters of the GB body, GB neck, cystic duct, and common bile duct (CBD) at papilla. Strong positive correlations existed between MRCP and corrosion casting for measuring GB body and neck, cystic duct, and CBD at the extrahepatic ducts' junction. In contrast to the reference methods, post-mortem MRCP did not visualize right and left extrahepatic ducts, and pancreatic ducts in most cats. Based on this study, MRCP with 1.5 Tesla can be regarded as a contributory method to improve the assessment of feline biliary tract and pancreatic ducts when their diameter is >1 mm.

Aberrant cortical projections to amygdala GABAergic neurons contribute to developmental circuit dysfunction following early life stress.

Early life stress (ELS) results in enduring dysfunction of the corticolimbic circuitry, underlying emotional and social behavior. However, the neurobiological mechanisms involved remain elusive. Here, we have combined viral tracing and electrophysiological techniques to study the effects of maternal separation (MS) on frontolimbic connectivity and function in young (P14-21) rats. We report that aberrant prefrontal inputs to basolateral amygdala (BLA) GABAergic interneurons transiently increase the strength of feed-forward inhibition in the BLA, which raises LTP induction threshold in MS treated male rats. The enhanced GABAergic activity after MS exposure associates with lower functional synchronization within prefrontal-amygdala networks in vivo. Intriguingly, no differences in these parameters were detected in females, which were also resistant to MS dependent changes in anxiety-like behaviors. Impaired plasticity and synchronization during the sensitive period of circuit refinement may contribute to long-lasting functional changes in the prefrontal-amygdaloid circuitry that predispose to neuropsychiatric conditions later on in life.

Downregulation of kainate receptors regulating GABAergic transmission in amygdala after early life stress is associated with anxiety-like behavior in rodents.

Early life stress (ELS) is a well-characterized risk factor for mood and anxiety disorders. GABAergic microcircuits in the amygdala are critically implicated in anxiety; however, whether their function is altered after ELS is not known. Here we identify a novel mechanism by which kainate receptors (KARs) modulate feedforward inhibition in the lateral amygdala (LA) and show that this mechanism is downregulated after ELS induced by maternal separation (MS). Specifically, we show that in control rats but not after MS, endogenous activity of GluK1 subunit containing KARs disinhibit LA principal neurons during activation of cortical afferents. GluK1 antagonism attenuated excitability of parvalbumin (PV)-expressing interneurons, resulting in loss of PV-dependent inhibitory control and an increase in firing of somatostatin-expressing interneurons. Inactivation of Grik1 expression locally in the adult amygdala reduced ongoing GABAergic transmission and was sufficient to produce a mild anxiety-like behavioral phenotype. Interestingly, MS and GluK1-dependent phenotypes showed similar gender specificity, being detectable in male but not female rodents. Our data identify a novel KAR-dependent mechanism for cell-type and projection-specific functional modulation of the LA GABAergic microcircuit and suggest that the loss of GluK1 KAR function contributes to anxiogenesis after ELS.

Porcine reproductive and respiratory syndrome type 1 viruses induce hypoplasia of erythroid cells and myeloid cell hyperplasia in the bone marrow of experimentally infected piglets independently of the viral load and virulence.

Porcine reproductive and respiratory syndrome viruses (PRRSV) present a wide phenotypic and genetic diversity. Experimental infections have demonstrated viral replication, including highly pathogenic strains (HP-PRRSV), in primary lymphoid organs such as the thymus. However, studies of the bone marrow are scarce but necessary to help elucidate the immunobiology of PRRSV strains of differing virulence. In this study, whereas viral RNA was detected within the bone marrow of animals experimentally infected with both low virulent Lelystad (LV) and 215-06 PRRSV-1 strains and with the highly virulent SU1-bel strain, PRRSV positive cells were only occasionally detected in one SU1-bel infected animal. PRRSV RNA levels were associated to circulating virus with the highest levels detected in LV-infected pigs. At 3 dpi, a decrease in the proportion of haematopoietic tissue and number of erythroid cells in all infected groups was associated with an increase in TUNEL or cleaved caspase 3 labelling and higher counts of myeloid cells compared to control. The expression of IL-1α and IL-6 was elevated at the beginning of the infection in all infected animals. The expression of TNF-α was increased at the end of the study in all infected groups with respect to control. Different PRRSV-1 strains induced, presummably by indirect mechanisms and independently of viral load and strain virulence, moderate and sustained hypoplasia of erythroid cells and myeloid cell hyperplasia at early stages of infection. These changes were paralleled by a peak in the local expression of IL-1α, IL-6 and TNF-α in all infected groups.

Thymic depletion of lymphocytes is associated with the virulence of PRRSV-1 strains.

Porcine reproductive and respiratory syndrome virus (PRRSV) exists as two distinct viruses, type 1 (PRRSV-1) and type 2 (PRRSV-2). Atrophy of the thymus in PRRSV-2 infected piglets has been associated with a loss of thymocytes. The present study aimed to evaluate the impact of PRRSV-1 strains of differing virulence on the thymus of infected piglets by analysing the histomorphometry, the presence of apoptotic cells and cells producing cytokines. Thymic samples were taken from animals experimentally infected (with LV, SU1-bel, and 215-06 strains) or mock inoculated animals at 3, 7 and 35days post-infection (dpi) and processed for histopathological and immunohistochemical analyses. PRRSV antigen was detected in the thymus from 3dpi until the end of the study in all virus-infected animals with the highest numbers of infected cells detected in SU1-bel group. The histomorphometry analysis and counts of CD3(+) thymocytes in the thymic cortex displayed significant differences between strains at different time-points (p≤0.011), with SU1-bel group showing the most severe changes at 7dpi. Cell death displayed statistically significant increase in the cortex of all infected animals, with SU1-bel group showing the highest rate at 3 and 7dpi. The number of cells immunostained against IL-1α, TNF-α and IL-10 were predominantly detected in the medulla (p≤0.01). An increase in the number of TNF-α and IL-10 positive cells was observed in LV and SU-1bel groups. Our results demonstrate that different PRRSV-1 strains induced depletion of the thymic cortex due to apoptosis of thymocytes and that the most severe depletion was associated with the highly virulent SU1-bel strain.

Evaluation of rapid methods for diagnosis of tuberculosis in slaughtered free-range pigs.

Free-range pigs can be infected by Mycobacterium tuberculosis complex (MTC) and may contribute to the spread of bovine tuberculosis (bTB). In the present study, the diagnostic values of bacteriological culture, a duplex real-time quantitative PCR and an antibody ELISA were evaluated in an abattoir study of submandibular lymph nodes and serum samples from 73 pigs with and without lesions consistent with bTB. The duplex qPCR was an accurate method for diagnosis of TB in pigs (specificity 100%; sensitivity 80%). Combining qPCR with histopathology improved sensitivity and had very good concordance (κ = 0.94) with the reference method. Serological results suggest that the antibody ELISA can be used for monitoring herds but not individuals.