Transmission studies of Hendra virus (equine morbilli-virus) in fruit bats, horses and cats

Objective To determine the infectivity and transmissibility of Hendra virus (HeV). Design A disease transmission study using fruit bats, horses and cats. Procedure Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second exper iment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experi ment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horses were inoculated at the conclusion of the third experiment: the first orally and the second by nasal swabbing. All animals were necropsied and examined by gross and microscopic pathological methods, immunoperoxidase to detect viral antigen in formalin-fixed tissues, virus isolation was attempted on tissues and SNT and ELISA methods were used to detect HeV-specific antibody. Results Clinical disease was not observed in the fruit bats, although six of eight inoculated bats developed antibody against HeV, and two of six developed vascular lesions which contained viral antigen. The in-contact bats and horses did not seroconvert. Three of four horses that were inoculated devel oped acute disease, but in-contact horses and cats were not infected. In the third experiment, one of three in-contact horses contracted disease. At the time of necropsy, high titres of HeV were detected in the kidneys of six acutely infected horses, in the urine of four horses and the mouth of two, but not in the nasal cavities or tracheas. Conclusions Grey-headed fruit bats seroconvert and develop subclinical disease when inoculated with HeV. Horses can be infected by oronasal routes and can excrete HeV in urine and saliva. It is possible to transmit HeV from cats to horses. Transmission from P poliocephalus t o horses could not be proven and neither could transmission from horses to horses or horses to cats. Under the experimental conditions of the study the virus is not highly contagious.     

Luteolytic Effect of Prostaglandin F2α on Bovine Corpus Luteum Depends on Cell Composition and Contact

Prostaglandin F_2α (PGF_2α) is a main luteolytic factor in vivo; however, its direct luteolytic influence on steroidogenic cells of bovine corpus luteum (CL) is controversial and not fully understood. The aim of the study was to clarify PGF_2α action on bovine CL in different in vivo and in vitro conditions and to examine whether the contact among all main types of CL cells is necessary for luteolytic PGF_2α action. In experiment 1, the bovine CL (day 15 of the oestrous cycle) was perfused using in vivo microdialysis system with dinoprost (an analogue of PGF_2α) for 0.5 h. Dinoprost caused a short‐time increase in progesterone (P4), whose concentration decreased thereafter (at 6‐, 10‐, 12‐ and 24‐h after treatment). In experiment 2, the direct effect of PGF_2α on P4 accumulation in CL steroidogenic cells cultured in monolayer (day 15 of the cycle) was determined. PGF_2α after 24 h of incubation increased P4 accumulation in steroidogenic CL cells. In experiment 3 steroidogenic, endothelial CL and immune cells (day 15 of the cycle) were incubated with PGF_2α in cocultures for 24 h in glass tubes and the levels of P4, stable metabolites of nitric oxide (NO) and leukotriene (LT) C₄ were determined. Although PGF_2α treatment increased P4 secretion in homogeneous steroidogenic CL cell culture, the decrease in P4 secretion in cocultures of all types of CL cells was observed. The secretion of NO and LTC₄ increased after the treatment of PGF_2α both in pure cultures of CL cells and in cocultures. The interactions between endothelial and immune cells with steroidogenic CL cells are needed for luteolytic PGF_2α action within the bovine CL. Our results indicate that the cell coculture model, including the main types of CL cells, is the most approximate to study PGF_2α role in vitro.     

Prevalence of the AMHR2 mutation in Miniature Schnauzers and genetic investigation of a Belgian Malinois with persistent Müllerian duct syndrome

Persistent Müllerian duct syndrome (PMDS) is a sex‐limited disorder in which males develop portions of the female reproductive tract. Important consequences of PMDS are cryptorchidism and its sequelae of infertility and increased risk of testicular cancer. Anti‐Müllerian hormone (AMH) and its receptor (AMHR2) induce the regression of the Müllerian ducts in male embryos. In Miniature Schnauzer dogs, the genetic basis has been identified as an autosomal recessive nonsense mutation in AMHR2, but the allele frequency of the mutation is unknown. Thus, the primary objective of this study was to estimate the prevalence of the AMHR2 mutation in North American Miniature Schnauzers, in order to ascertain the value of genetic testing in this breed. An additional objective was to determine whether mutations in AMH or AMHR2 were responsible for PMDS in a Belgian Malinois; this would aid development of a genetic test for the Belgian Malinois breed. Genomic DNA from 216 Miniature Schnauzers (including one known PMDS case) was genotyped for the AMHR2 mutation, and DNA from a single PMDS‐affected Belgian Malinois was sequenced for all coding exons of AMH and AMHR2. The Miniature Schnauzer cohort had an AMHR2 mutation allele frequency of 0.16 and a carrier genotypic frequency of 0.27. The genetic basis for PMDS in the Belgian Malinois was not determined, as no coding or splicing mutations were identified in either AMH or AMHR2. These findings support a benefit to AMHR2 mutation testing Miniature Schnauzers used for breeding or with cryptorchidism.     

Effect of housing system on reproductive behaviour and on some endocrinological and seminal parameters of donkey stallions

Reproductive management of male donkeys employed for artificial breeding has been poorly studied. The aim of this study was to evaluate the effect of housing system, with the animals grouped together in a paddock or kept in individual boxes, on sexual behaviour, cortisol and testosterone concentration and seminal characteristics of adult male donkeys. The study included four Amiata donkey jacks (stallions) from which ejaculates, saliva and blood were collected during two distinct 3 weeks periods, one in the group and one in the box housing system. Time needed for semen collection was shorter when donkeys were kept in paddocks compared to when they were kept in single boxes (14:57 ± 07:27 and 20:52 ± 09:31 min, p < .05). Native semen characteristics were not influenced by housing system, while cooled preservation in an Equitainer^® showed that sperm motility parameters were significantly higher during the paddock period compared to the box period. Salivary cortisol was influenced by housing system, both before and 60 min after ejaculation, being statistically higher when donkeys were housed in paddocks. On the contrary, overall and basal testosterone concentrations were significantly higher when animals were kept in boxes. In conclusion, in the present study, good quality semen could be successfully collected from donkeys irrespective of the housing system despite some differences in hormone concentrations.     

24-Hour Secretion Patterns of Plasma Oestradiol 17β in Pony Mares in Late Gestation

The mare exhibits nocturnal uterine contractions in the last 6 days of gestation. It is hypothesized that estradiol 17β (O17β) may be associated with the nightly increase in uterine contractions. The 24‐h secretion pattern of plasma O17β was measured in 3 pony mares in late gestation to identify changes in release as the mare neared parturition. Blood was collected weekly at 08:00 hours beginning on day 240 and every third day from day 330 until delivery. Serial blood samples were collected from each mare every 30‐min for 24‐h beginning on gestation day 310 and every sixth day thereafter until parturition. Concentrations of O17β were elevated at night with lowest concentrations occurring directly before sunset (p < 0.01). The natural log of the variance was increased at sunset (p < 0.01) and was decreased during the 6‐h period immediately after sunrise. This pattern was especially evident in the 6 days that preceded parturition. The contrast between nocturnal and daytime concentrations of O17β in the last 6 days of gestation may contribute to night‐time delivery in the mare.     

Alzheimer type II astrocytes in the brains of pigs with salt poisoning (water deprivation/intoxication)

The finding of Alzheimer type II astrocytes, in addition to the pathognomonic combination of laminar cerebrocortical necrosis and eosinophil infiltration, in the brains of pigs is reported for the first time in cases of indirect salt poisoning following water deprivation.     

Gold nanoelectrodes of varied size: transition to molecule-like charging

A transition from metal-like double-layer capacitive charging to redox-like charging was observed in electrochemical ensemble Coulomb staircase experiments on solutions of gold nanoparticles of varied core size. The monodisperse gold nanoparticles are stabilized by short-chain alkanethiolate monolayers and have 8 to 38 kilodaltons core mass (1.1 to 1.9 nanometers in diameter). Larger cores display Coulomb staircase responses consistent with double-layer charging of metal-electrolyte interfaces, whereas smaller core nanoparticles exhibit redox chemical character, including a large central gap. The change in behavior is consistent with new near-infrared spectroscopic data showing an emerging gap between the highest occupied and lowest unoccupied orbitals of 0.4 to 0.9 electron volt.     

Diagnostic ultrasound in veterinary practice: How safe is it?

This paper provides information on the safety of ultrasonic diagnostic procedures as currently used in veterinary practice. The known mechanisms of action are described and selected literature on biological effects of ultrasound is reviewed. Current international consensus is presented on the safety of medical ultrasound with respect to thermal effects. To date, there is no independently verified clinical evidence that the level of exposure delivered to the tissues during scanned grey-scale (‘B-mode’) imaging has any adverse effects. Lung haemorrhage has been observed in animal experiments using diagnostic exposures, but the effects have not been reported in the foetus. Equipment that uses pulsed Doppler transmits higher acoustic outputs in a stationary beam, and can produce temperature increases that may have significant biological consequences. When considering sonographic and pulsed Doppler examinations of the prenatal animal, the safety margins are small and the operator should be aware of the acoustic output of the equipment, the exposure time, and the sensitivity of target tissues.