Right ventricular systolic and diastolic function assessed by two-dimensional speckle tracking echocardiography in dogs with myxomatous mitral valve disease

Pulmonary hypertension (PH) is a common comorbidity in dogs with myxomatous mitral valve disease (MMVD), and can induce various changes in the right heart, such as right ventricular (RV) hypertrophy, dilatation, and dysfunction. We hypothesized that RV function, not only systolic function but also diastolic function, could be worsened with PH progression. We aimed to compare RV systolic and diastolic function in dogs with MMVD. Twenty healthy dogs and sixty-eight dogs with MMVD were enrolled. Dogs with MMVD were classified into the probability of PH. Two-dimensional and Doppler echocardiographic indices for right heart and two-dimensional speckle tracking echocardiography indices were measured. The morphological indicators of the right heart were significantly higher only in the high probability of PH group. The RV strain, early-diastolic and systolic strain rates were significantly lower in the high probability of PH group than those in the low and intermediate probability of PH groups. Multivariate analysis showed that increased RV internal dimension normalized by body weight and RV myocardial performance index were significantly associated with the presence of right-sided congestive heart failure. Speckle tracking echocardiography-derived RV systolic and diastolic function were activated in the low and intermediate probability of PH groups. However, dogs with high probability of PH showed RV myocardial dysfunction and dilatation. Increased RV myocardial performance index and end-diastolic RV internal dimension normalized by body weight were significantly associated with the presence of right-sided congestive heart failure in dogs with MMVD.     

Hypothalamo-pituitary-adrenal gland axis in mice inhaling toluene prior to low-level long-term exposure to formaldehyde

We studied the change in the hypothalamo-pituitary-adrenal gland (HPA) axis upon adding prior toluene inhalation to our previous formaldehyde inhalation experiments to determine whether short term exposure to relatively high levels of toluene triggers multiple chemical sensitivity (MCS). Data come from immunocytochemical, morphometrical and RT-PCR measurements. Four groups of adult female mice were exposed to differing concentrations (0, 80, 400, and 2,000 ppb) of formaldehyde for 16 hr/day, 5 days/week for twelve weeks, after the mice were exposed intranasally to 500 ppm toluene per mouse for 6 hr/day, for 3 days. We found that the number of corticotropin releasing hormone (CRH)-immunoreactive (ir) neurons was up-regulated according to the amount of formaldehyde as well as inhalation of formaldehyde alone in our previous experiment. The proportion of adrenocorticotropin hormone (ACTH)-ir cells increased according to the formaldehyde concentration, though there was no significant difference between the 400 and 2,000 groups. The number of ACTH-ir cells was higher in the 400 group than in the other groups (0, 80, and 2,000). Expression of ACTH-mRNA was also up-regulated according to the quantity of formaldehyde. The sinusoid in the anterior pituitary showed more dilatation in the 400 and 2,000 groups than in the control group, especially in the 2,000 group. We propose that exposure to toluene prior to inhalation of formaldehyde has no effect on the HPA axis and as a trigger of MCS, although greater sinusoid dilatation was found in the anterior pituitary gland at higher concentrations of formaldehyde.     

High prevalence of Mycoplasma equirhinis in Thoroughbred horses with respiratory symptoms in autumn 2018

Mycoplasma species are often isolated from horses with respiratory symptoms; however, the pathogenicity of Mycoplasma is still unclear. In autumn of 2018, we encountered an increase in cases with respiratory symptoms, mainly coughing, in a group of Thoroughbred racehorses in Japan. We examined tracheal wash samples obtained from 40 of those cases. Bacteria and viruses that commonly cause respiratory symptoms were investigated, and anaerobes were detected in only 5 cases and Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) was detected in only 1 case of 40 cases with loop-mediated isothermal amplification assay. S. zooepidemicus and Streptococcus pneumoniae were isolated at a bacterial count of higher than 1.0 × 10⁴ CFU/ml from 5 and 2 cases of 28 cases cultured, respectively. None of the viruses investigated was detected in 40 cases. Mycoplasma equirhinis (M. equirhinis) was isolated from 40.0% (16/40) of the cases, which was higher than previously reported isolation rates. The rate of M. equirhinis isolation in the cases from 2018 was significantly higher than the isolation rates in the other horses: clinical cases with respiratory symptoms in 2019–2020 (13.6%, 3/22) and healthy horses (13.5%, 5/37) in Japan. In this study, the isolation rate of M. equirhinis from horse group with cough symptoms in 2018 was high and no other common etiological agents were detected. The pathogenesis of M. equirhinis is still unclear, however, M. equirhinis might have been associated with respiratory symptoms in the Thoroughbred horse cases in 2018.     

CD56 is expressed exclusively on CD3+ T lymphocytes in canine peripheral blood

CD56+ cells in canine blood leukocytes were characterized by flow-cytometric analysis of peripheral blood of 30 healthy adult beagle-dogs (15 males and 15 non-pregnant females). In 19 of the 30 dogs, anti human CD56 antibody, Leu-19, reacted with 8.8-21.7% of peripheral blood lymphocytes. All CD56+ cells simultaneously expressed CD3 molecules on their surface. Further phenotypic analysis revealed that 50.6+/-13.1% of the CD56+ cells showed CD4-CD8+ phenotype and 43.7+/-10.1% showed CD4+CD8- phenotype. Expression intensity of CD56 on the CD4-CD8+CD56+ cells was significantly higher than that on CD4+CD8-CD56+ cells (P<0.001). These findings indicate that CD56, which is a neural cell adhesion molecule, is uniquely expressed on subsets of T lymphocytes in canine peripheral blood.     

Epidemiological and morphological studies of double-chambered right ventricle in dogs

The double-chambered right ventricle (DCRV) is a rare congenital cardiac disease in dogs, and its detailed epidemiological and morphological features are not clearly understood. By investigating the profile, clinical signs, and characteristics of examination findings of eleven dogs with DCRV by means of a retrospective study, we attempted to clarify the epidemiology and morphology of the condition. The study group consisted of nine males and two females. Breeds included Pug (n=3), Miniature Dachshund (n=1), French Bull-dog (n=1), Shiba (n=1), and Retrievers (n=5). The attachment site of the anomalous muscular bundle was continuous with the cardiac apex in nine dogs, and it was attached to the right ventricle free wall in the other two dogs. In dogs with DCRV, at least one of the following conditions was present concurrently: congenital or acquired tricuspid valve regurgitation (TR), ventricular septal defect, and atrial septal defect. Also, the pressure difference between the two chambers increased over time, and progressive right-sided heart failure was observed. In summary, DCRV occurs in small breeds of dog as well as in large breeds of dog and it may be more prevalent in males. The existence of two types of DCRV in dogs was established. Dog with DCRVs will have a high incidence of concurrent cardiac abnormalities. Concurrent TR may be either congenital or acquired. DCRV is a congenital disorder, but the clinical condition progresses as the dog develops.     

Identification of organically bound iodine in soil humic substances by size exclusion chromatography / inductively coupled plasma mass spectrometry (SEC / ICP-MS)

Abstract

Sulfur transformation in riee rhizosphere was investigated. Soil enzyme arylsulfatase in rhizosphere and non-rhizosphere soil, whieh is responsible for mineralization of organic sulfur to sulfate sulfur, was studied. The Michaelis constants of arylsulfatase from Maahas c1ay and Pila c1ay loam were 3.04 × 10^-4 M and 3.97 × 10^-4 M, respectively. The arylsulfatase of rhizosphere soil showed higher activity than that of non-rhizosphere soil. Applieation of sulfate had no marked elTect on the enzyme aetivity either in rhizosphere or non-rhizosphere soil under the submerged condition. This indieates that arylsulfatase activity under the submerged condition is not inhibited by applieation of sulfate. The amount of HI-reducible sulfur in the rhizosphere and non-rhizosphere soi! inereased with time. However, rhizosphere soil had a higher amount of HI-reducible sulfur than did non-rhizosphere. Thc ditl'erence in arylsulfatase activity between the rhizosphcre and non-rhizosphere soil was not directly associated with thc number of sulfur-redueing and -oxidizing bacteria.     

Toluene Exposure Leads to a Change in Expression Patterns of β Defensins in the Mouse Tracheal Epithelium

Defensins are generally implicated in the quick resistance of epithelial surfaces to microbials; however, recent reports have indicated that defensins also have unknown purposes in relation to noninfectious diseases. In this study, the localization patterns of anti-microbial peptides, β defensins (BDs), in the tracheal epithelium of male C3H mice under exposure to toluene were analyzed by immunohistochemistry. Mice were exposed one to ten times to toluene for 30 min by nose-only inhalation. Expression of BDs was revealed by immunohistochemistry in serial sections of trachea after the final exposure. Expression of BD-1 was usually observed at almost the same levels in all exposure groups, and expression of BD-2 was observed in the control group; however, the signals for BD-2 decreased gradually with frequency of exposure. In the group exposed ten times, expression of BD-2 decreased to far lower than that of the control group. No expression of BD-3 was detected in any groups. Interestingly, expression of BD-4 increased to the maximum in the group exposed four times and decreased to a level lower than that of the control in the group exposed ten times. The results of the present study indicated that toluene gas might change the expression pattern of BDs in the tracheal epithelial cells. The oscillation of expression of BD-4 was quite characteristic and might contribute to morphological damage in on the epithelial cells.     

Equine keratomycosis in Japan

Objective To describe the incidence, clinical progress, visual outcome, and laboratory findings of equine keratomycosis in Japan. Procedure Retrospective study of the medical records of horses clinically and mycologically diagnosed with keratomycosis at the Equine Hospitals of the Japan Racing Association from 2005 to 2011. Results The diagnosis of keratomycosis was confirmed in eight horses (40.0% of the 20 horses with infectious keratitis from which fungi and/or bacteria were isolated). Fungi recovered from corneal swabs were identified as Aspergillus flavus (4), Aspergillus niger (1), Fusarium solani (1), and Mortierella wolfii (2). All horses were treated medically with topical antifungals, and one horse was also treated surgically. The median of treatment period was 40 days. Two horses were rendered blind in the affected eye and the others retained vision. Conclusions Equine keratomycosis comprises a considerable portion of infectious keratitis in Japan, and the causative fungi that we isolated had been isolated previously from horses with keratomycosis in other regions with the exception of M. wolfii. Culture and cytological examination of corneal lesions should be immediately performed on eyes with signs of keratitis, particularly on those not improving with antibacterial medication, as early initiation of aggressive antifungal treatment tended to result in better outcome and shorter treatment period.     

Influence of heart rate on myocardial function using two-dimensional speckle-tracking echocardiography in healthy dogs

ObjectiveThe objective of this study was to evaluate the influence of heart rate (HR) on myocardial function assessed by two-dimensional speckle-tracking echocardiography (2D-STE) in healthy dogs.AnimalsThirteen healthy beagle dogs.MethodsAnimals were anesthetized and HR was controlled with right atrial pacing. Myocardial function of each dog was assessed using 2D-STE at pacing rates of 120, 140, 160, and 180 bpm.ResultsAll strain and strain rate variables in the longitudinal, circumferential, and radial directions were not significantly different between pacing rates. Peak early diastolic torsion rate at 180 bpm was significantly increased compared with that at 120 bpm (P = 0.003).ConclusionTorsion rate in early diastole was elevated at 180 bpm, which may reflect improved myocardial relaxation with higher HR. Changes in left ventricular torsion during tachycardia may play an important role in preserving stroke volume in the presence of shortened ejection and filling times.     

Changes in Serum Antibody Levels after Vaccination for Strangles and after Intranasal Challenge with Streptococcus equi subsp. equi in Horses

In this study, to evaluate the influence of strangles vaccination on serological test results, we investigated the changes in strangles serum antibody levels in horses after vaccination and subsequent intranasal challenge with S. equi. The horses were vaccinated for strangles with either a component vaccine (Group C) or a live vaccine (Group L). We measured changes in strangles serum antibody levels weekly for 20 weeks after vaccinating horses twice for strangles over a 3-week interval, and for 7 weeks after intranasal challenge with S. equi in the same horses. Serum antibody responses to the proline-glutamic acid-proline-lysine (PEPK) antigen with five repetitions (PEPK-5R) were higher at all times (up to 2.4-fold) following vaccination in Group C than in Group L, and the value peaked at 2.9-fold above the initial value after the second vaccination in Group C horses. However, the value was lower than that in horses infected with S. equi, and it gradually decreased, reaching the initial (week 0) value by the 15th week. Serum antibody responses to PEPK-5R after challenge with S. equi increased in both groups of horses, but the value tended to be lower than that reported for unvaccinated horses. In addition, the average value in Group C was 2.6-fold higher than that of Group L. These results suggest the serum antibody responses of horses infected with S. equi varies according to the type of vaccine with which they have been vaccinated. Although the serological diagnostic test for strangles in which PEPK-5R is used as an antigen is effective for the investigation of serum antibodies to strangles in vaccinated horses, the present data suggest it is necessary to consider the vaccination history when interpreting the results.