Blastocyst-like Structures in the Peripheral Retina of Young Adult Beagles.

In this immunohistological study on the peripheral retina of 3-year-old beagle dogs, excised retina specimens were immunostained with antibodies against nestin, Oct4, Nanog, Sox2, CDX2, cytokeratin 18 (CK 18), RPE65, and YAP1, as well as hematoxylin and DAPI, two nuclear stains. Our findings revealed solitary cysts of various sizes in the inner retina. Intriguingly, a mass of small round cells with scant cytoplasms was observed in the cavity of small cysts, while many disorganized cells partially occupied the cavity of the large cysts. The small cysts were strongly positive for nestin, Oct4, Nanog, Sox2, CDX2, CK18, and YAP1. RPE65-positive cells were exclusively observed in the tissue surrounding the cysts. Since RPE65 is a specific marker of retinal pigment epithelial (RPE) cells, the surrounding cells of the peripheral cysts were presumably derived from RPE cells that migrated intraretinally. In the small cysts, intense positive staining for nestin, a marker of retinal stem cells, seemed to indicate that they were derived from retinal stem cells. The morphology and positive staining for markers of blastocyst and RPE cells indicated that the small cysts may have formed structures resembling the blastocyst, possibly caused by the interaction between retinal stem cells and migrated RPE cells.

[Rhodococcus equi infections in humans: an emerging zoonotic pathogen].

Rhodococcus equi is a facultative intracellular gram-positive coccobacillus which is a well-known cause of foal pneumonia and/or enteritis in equine veterinary medicine. More than 300 cases of R. equi infection have been reported since the first description of human disease in 1968. Most patients who become infected with R equi are immunocompromised, such as those infected with human immunodeficiency virus (HIV), recipients of organ transplantation, and patients receiving cancer treatment. However, there are increasing reports of the immunocompetent hosts. The pathogenicity of R. equi has been attributed to the presence of plasmid-encoded virulence-associated proteins (Vap). To date, three host-associated virulence plasmid types of R. equi have been identified as follows: the circular pVAPA and pVAPB, related, respectively, to equine and porcine isolates in 1991 and 1995, and a recently described linear pVAPN plasmid associated with bovine and caprine strains in 2015. More recently, these three plasmid types have been re-found in the human isolates which were isolated during 1980s to 1990s. Not only horses, but also pigs, goats, cattle and their environment should be considered as a potential source of R. equi for humans. In this review, we shed light on the current understanding of R. equi as an emerging zoonotic pathogen.

Evaluation of Alacepril Administration in Canine Patent Ductus Arteriosus According to Plasma Chymase Activity.

Chymase in the renin-angiotensin system (RAS) actively contributes to cardiac disease progression. Chymase is activated to produce angiotensin II during tissue injury and is involved in hemodynamics. A recent study demonstrated that plasma chymase activity reflects hemodynamic changes and aids in understanding patent ductus arteriosus (PDA) pathophysiology. The present study examined the relationship between plasma chymase activity and the administration of angiotensin-converting enzyme (ACE) inhibitor. Alacepril was administered to 13 puppies with PDA. Conventional echocardiographic parameters and non-invasive blood pressure were measured before and after medication. Plasma chymase activity was calculated using the colorimetric absorbance method. Plasma chymase activity significantly increased, but blood pressure significantly decreased. We detected an increase in plasma chymase activity due to ACE inhibition in PDA cases treated with alacepril. Plasma chymase activity was affected and altered by alacepril. In veterinary medicine, plasma chymase activity may be a novel method for assessing the pathology of and therapy for cardiac diseases.

Isolation of vapB-positive Rhodococcus equi from submaxillary lymph nodes with or without granulomatous lesions in growing-finishing pigs in Japan.

To investigate the etiological role of vapB-positive Rhodococcus equi in pigs, R. equi was isolated from the submaxillary lymph nodes with or without macroscopically detectable lesions of apparently healthy growing-finishing pigs at a slaughterhouse in Toyama Prefecture, Japan. R. equi was isolated from 57 (24.6%) of 232 pigs with macroscopically detectable lymph node lesions, and 56 (98.2%) of the 57 isolates were vapB-positive. R. equi was isolated from 10 (2.4%) of 420 pigs without lymph node lesions, and six (60%) of the 10 isolates were vapB-positive. Plasmid DNA was isolated from the 62 vapB-positive isolates and digested with EcoRI and NsiI to obtain the plasmid profile. Fifty-two (83.9%), three (4.8%), and four (6.5%) isolates contained pVAPB subtypes 1, 2, and 3, respectively, while the remaining three isolates were of pVAPB subtypes 9, 13, and 14, respectively. Twelve specimens from lymph nodes with macroscopically detectable lesions were randomly selected for histopathological staining. Granulomatous lesions resembling tuberculosis were found in 11 of the 12 specimens, and the remaining specimen showed typical foci of malakoplakia in the lymph node. The isolation rates of R. equi and vapB-positive R. equi from lymph nodes with macroscopically detectable lesions were significantly higher (P<0.05) than those of lymph nodes without lesions, suggesting an etiologic association between vapB-positive R. equi and macroscopically detectable granulomatous lesions in porcine submaxillary lymph nodes. Previous reports on the prevalence of vapB-positive R. equi in pigs are reviewed and discussed.

Experimental infection of goats with pVAPN-harboring Rhodococcus equi causes latent infection in the lymph nodes.

Rhodococcus equi has recently been identified in various animals, including ruminants. Several studies have highlighted the emergence of pVAPN-harboring strains, isolated from multiple abscesses, in the liver and lungs of ruminants. Epidemiological evidence strongly suggests that pVAPN-harboring strains are pathogenic in ruminants. This study aims to replicate the disease in goats through experimental infection. Intravenous administration of the pVAPN-harboring strain (Yokkaichi), pVAPA-harboring strain (ATCC33701), and pVAPN-cured strain (Yokkaichi_P-), each at 1.0 × 107 CFU/head, was conducted in 24-month-old goats (n = 1 per group). During the observation period, goats treated with Yokkaichi or ATCC33701 exhibited transient increases in body temperature and white blood cell count, alongside a decrease in body weight from the administration day. Conversely, goats treated with Yokkaichi_P- displayed no significant changes in these values. The Yokkaichi-treated goat demonstrated a >10-fold increase in anti-VapN antibody titers from 11 to 14 days postadministration, whereas the other two goats exhibited no variation in anti-VapA and VapN antibody titers. Pathological autopsy analysis of organs harvested 28 days postadministration revealed no characteristic lesions on gross examination. However, the inoculated strain (vapN-positive R. equi) was exclusively recovered from the tracheobronchial lymph node in the Yokkaichi-treated goat. Immunohistochemistry detected a VapN-positive reaction in the tracheobronchial lymph node, confirming latent infection despite the absence of dramatic suppurative lesions seen in ruminants. Overall, this study highlights the latent infection in lymph nodes induced by the pVAPN-harboring strain, despite the absence of overt pathological manifestations.