TRANS-SPLENIC PORTAL SCINTIGRAPHY IN NORMAL DOGS

The purpose of this study was to (1) establish a technique for ultrasound-guided trans-splenic portal scintigraphy (TSPS) using 99mTcO4(-), (2) evaluate portal vein morphology, (3) compare the radiation exposures for TSPS vs. per-rectal portal scintigraphy (PRPS), and (4) compare the quality of numerical data from the TSPS vs. PRPS. Eight juvenile dogs underwent PRPS and TSPS (minimum of 48h between studies) after initial screening tests. PRPS was done according to established protocol using 425 +/- 36MBq (mean +/- SD) of 99mTcO4(-). TSPS was done with the dogs in right lateral recumbency over the gamma camera. 99mTcO4(-) (57 +/- 13.9 MBq) was injected into the spleen 1-2s following initiation of the dynamic acquisition. The frame rate was 4 frames/s for 5 min. There was significantly lower radioactivity of 99mTcO4(-) given and significantly higher total counts recorded in the liver and heart during the TSPS compared with PRPS. The total counts for the TSPS and PRPS were 7120 +/- 4386 and 830 +/- 523, respectively. Percent absorption from the spleen was 52.5 +/- 19.1% compared with 9.2 +/- 5.7% for the colon. Calculated transit time for the TSPS studies was 7 +/- 2.3s. In TSPS studies, the splenic and portal veins were clearly identified. Radiation exposure levels of the dogs were significantly lower following TSPS than after PRPS. TSPS appears superior to PRPS as a method to image the portal venous system representing a valid alternative diagnostic test for animals with suspected portosystemic shunts.     

Neural encoding of olfactory recognition memory

Our work with both sheep and mouse models has revealed many of the neural substrates and signalling pathways involved in olfactory recognition memory in the main olfactory system. A distributed neural system is required for initial memory formation and its short-term retention-the olfactory bulb, piriform and entorhinal cortices and hippocampus. Following memory consolidation, after 8 h or so, only the olfactory bulb and piriform cortex appear to be important for effective recall. Similarly, whereas the glutamate-NMDA/AMPA receptor-nitric oxide (NO)-cyclic GMP signalling pathway is important for memory formation it is not involved in recall post-consolidation. Here, within the olfactory bulb, up-regulation of class 1 metabotropic glutamate receptors appears to maintain the enhanced sensitivity at the mitral to granule cell synapses required for effective memory recall. Recently we have investigated whether fluctuating sex hormone levels during the oestrous cycle modulate olfactory recognition memory and the different neural substrates and signalling pathways involved. These studies have used two robust models of social olfactory memory in the mouse which either involve social or non social odours (habituation-dishabituation and social transmission of food preference tasks). In both cases significant improvement of learning retention occurs when original learning takes place during the proestrus phase of the ovarian cycle. This is probably the result of oestrogen changes at this time since transgenic mice lacking functional expression of oestrogen receptors (ERalpha and ERbeta, the two main oestrogen receptor sub-types) have shown problems in social recognition. Therefore, oestrogen appears to act at the level of the olfactory bulb by modulating both noradrenaline and the glutamate/NO signalling pathway.     

Comparison of Seven Digital Cameras for Digitizing Radiographs

The purpose of this study was to evaluate seven digital cameras for their ability to adequately capture quality radiographic images and their relative cost effectiveness. Radiographs of line pair (LP) phantoms (ranging from 0.6 to 16.6 LP/mm) and a 20-step contrast phantom were photographed at a near distance of 30.0 cm and a far distance (determined for each camera) at which a full 14 x 17 in film filled the viewfinder. Of the seven cameras tested, the Canon EOS-D30 consistently performed the best in LP/mm resolved (7.7 at close distance, 1.4 at far distance) and in contrast latitude (all 20 steps at both close and far distances). The Canon EOS-D30, determined to be the best camera used in this study for photographing radiographic images, is also the most expensive camera that was used. Two cameras, the Nikon Coolpix 995 and the Sony DSC-F707, were very close to the Canon in performance at considerably less cost. Certain inexpensive cameras may not be acceptable choices for teleradiology.     

Seasonality in Saint Croix male lamb reproductive development in northern Mexico

The aim of this study was to determine the influence of the season of birth on the body weight, testicular size, testosterone concentrations, semen output and sexual behaviour in Saint Croix male lambs. Thirty‐three lambs were born in spring (n = 10), summer (Sum; n = 12) or autumn (n = 11). Body weight and the scrotal circumference were weekly recorded; semen was also weekly collected by electroejaculation; and sexual behaviour towards oestrous ewes was weekly evaluated. Data were recorded from 15 to 33 weeks of age. The reproductive development of Saint Croix male lambs differed according to the period in which they were born. More lambs born in spring than in summer and autumn achieved puberty during this study and were also more precocious in semen production and displayed sexual behaviour earlier. Lambs born in summer delayed their semen production; however, season‐related negative effects were less pronounced at the end of the study than in autumn born lambs born. In conclusion, despite the apparently low seasonality of the breed, Saint Croix male lambs showed in this study a seasonal pattern in their reproductive development at least until they achieve the puberty.     

Chemical restraint of peccaries with tiletamine/zolazepam and xylazine or tiletamine/zolazepam and butorphanol

Objective To evaluate the use of a combination of tiletamine/zolazepam and xylazine (TZX) in collared and white‐lipped peccaries and to compare its efficacy as an anesthetic technique with that of tiletamine/zolazepam and butorphanol (TZB). Study design Prospective experimental trial. Animals Seven white‐lipped peccaries (Tayassu pecari) (four females and three males) and four collared peccaries (Tayasu tajacu) (two males and two females). Methods Animal immobilization was attempted with TZX and TZB (IM) on two different occasions. Heart and respiratory rates (HR, RR), rectal temperature (RT), sedation, muscle relaxation, posture, auditory response and analgesia were evaluated every 15 minutes during immobilization. Induction, anesthesia, standing and walking time were determined after drug administration. Results Doses for white‐lipped peccaries were 1.23 ± 0.26 mg kg^?1 (mean ± SD) of TZ and 1.23 ± 0.26 mg kg^?1 of X, and 1.46 ± 0.09 mg kg^?1 of TZ and 0.14 ± 0.008 mg kg^?1 of B; doses for collared peccaries were 1.51 ± 0.29 mg kg^?1 of TZ and 1.51 ± 0.29 mg kg^?1 of X and 1.68 ± 0.02 mg kg^?1 of TZ and 0.17 ± 0.002 mg kg^?1 of B. In white‐lipped peccaries, both drug combinations provided a smooth induction and good immobilization for more than an hour. Anesthesia and standing times were significantly longer in animals given TZB, whereas walking time was significantly longer in animals given TZX. A significant decrease in HR was observed with both treatments. Respiratory rate decreased significantly with TZX, but the rate remained higher than with TZB. Induction and recovery quality in white‐lipped peccaries was better with TZB than with TZX. Neither protocol provided adequate immobilization in collared peccaries. Conclusion and clinical relevance At the doses described, TZB is effective in providing a long period of immobilization, whereas TZX is adequate for short to medium immobilization in white‐lipped peccaries. Neither drug combination was effective in collared peccaries at the doses given.     

Initial sequence characterization of the rhabdoviruses of squamate reptiles, including a novel rhabdovirus from a caiman lizard (Dracaena guianensis)

Rhabdoviruses infect a variety of hosts, including non-avian reptiles. Consensus PCR techniques were used to obtain partial RNA-dependent RNA polymerase gene sequence from five rhabdoviruses of South American lizards; Marco, Chaco, Timbo, Sena Madureira, and a rhabdovirus from a caiman lizard (Dracaena guianensis). The caiman lizard rhabdovirus formed inclusions in erythrocytes, which may be a route for infecting hematophagous insects. This is the first information on behavior of a rhabdovirus in squamates. We also obtained sequence from two rhabdoviruses of Australian lizards, confirming previous Charleville virus sequence and finding that, unlike a previous sequence report but in agreement with serologic reports, Almpiwar virus is clearly distinct from Charleville virus. Bayesian and maximum likelihood phylogenetic analysis revealed that most known rhabdoviruses of squamates cluster in the Almpiwar subgroup. The exception is Marco virus, which is found in the Hart Park group.