The diagnosis and treatment of a thoracic abscess in an alpaca

A 6-month-old alpaca presented for lethargy, failure to thrive and leucocytosis. Diagnostic procedures, including thoracic ultrasound, radiographs and a computed tomography scan, were used to document a thoracic mass. Based on appearance and ultrasound-guided aspiration of purulent material, the mass was determined to be a large abscess. The abscess was treated with surgical drainage and long-term antibiotic therapy. The origin of this thoracic abscess was felt to be the caudal mediastinum, secondary to bacterial seeding of the caudal mediastinal lymph nodes. Although an aetiological agent was not definitively determined, the most likely was Actinomyces spp or Arcanobacterium pyogenes. The alpaca made a complete recovery following treatment.     

Residues from long-acting antimicrobial preparations in injection sites in cattle

Objective To investigate tissue residues of two longacting oxytetracycline (OTC) preparations in cattle.
Design A randomised drug residue trial.  

Animals

Two hundred and forty beef cattle in 24 groups of ten.
Procedure Two blind-coded 200 mg/mL OTC preparations were used in five treatment regimens of various combinations of injection sites (from one to five) and administrations (one or two). Five cattle from each group were slaughtered at 21, 30 and 60 days after injection and the injection site, urine, kidney and diaphragm muscle analysed for residues.
Results The OTC concentration exceeded the maximum residue limit in kidney in animals slaughtered 21 days after treatment, which is the prescribed withholding period. Concentration at the injection site was much greater than the maximum residue limit 30 days post-treatment, but not 45 days post-treatment. The residue was smaller when OTC had been injected in multiple sites. There was no difference between the two OTC preparations.
Conclusion A review of the maximum injection volume, site of injection and the withholding period is needed for long-acting OTC formulations.     

Length of veterinary working life

Objective To estimate the time veterinary graduates spend in private practice and in veterinary work generally, and to determine what factors influence this.
Methods Questionnaires were completed in the sixth year after graduation by 119 veterinarians who had participated in this longitudinal study since starting the veterinary course, and the data were analysed using the SAS System for Windows.
Results Of those who started the veterinary course, 90% graduated, and 96% of these then entered private practice. Five years later 94% (73% in full-time equivalents) were working as veterinarians, and 64% (50% in full-time equivalents) were still in private practice in Australia. Hours, attitudes of principals and clients, and inadequate rewards were the main reasons for leaving private practice. The likelihood of being still in private practice was greater for those who had had significant responsibility for animals before they entered the course, but it was not related to geographical origin (city vs country), age at entry or gender. Women were, however, more likely than men to be working part time as veterinarians. Predictions of veterinary working life were not affected by geographical origin or by previous experience with animals or on farms, but men expected to work longer than women.
Conclusion The average veterinary career, estimated by veterinarians who graduated 5 years earlier, is 24 years in fulltime equivalents for men, and 16 years for women. Almost all (94%, representing 73% in full-time equivalents) still work as veterinarians after 5 years, most of them (76%, representing 59% in full-time equivalents) in private practice. The likelihood of remaining in private practice is related to previous responsibility for animals.     

Melting of (Mg,Fe)2SiO4 at the Core-Mantle Boundary of the Earth

The lower mantle of the Earth is believed to be largely composed of (Mg,Fe)O (magnesiowustite) and (Mg,Fe)SiO3 (perovskite). Radiative temperatures of single-crystal olivine [(Mg0.9,Fe0.1)2SiO4] decreased abruptly from 7040 +/- 315 to 4300 +/- 270 kelvin upon shock compression above 80 gigapascals. The data indicate that an upper bound to the solidus of the magnesiowustite and perovskite assemblage at 4300 +/- 270 kelvin is 130 +/- 3 gigapascals. These conditions correspond to those for partial melting at the base of the mantle, as has been suggested occurs within the ultralow-velocity zone beneath the central Pacific.     

Structure and function of an essential component of the outer membrane protein assembly machine

Integral beta-barrel proteins are found in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. The machine that assembles these proteins contains an integral membrane protein, called YaeT in Escherichia coli, which has one or more polypeptide transport-associated (POTRA) domains. The crystal structure of a periplasmic fragment of YaeT reveals the POTRA domain fold and suggests a model for how POTRA domains can bind different peptide sequences, as required for a machine that handles numerous beta-barrel protein precursors. Analysis of POTRA domain deletions shows which are essential and provides a view of the spatial organization of this assembly machine.     

Components of electroencephalographic responses to slaughter in halothane-anaesthetised calves: Effects of cutting neck tissues compared with major blood vessels

AIM: To identify whether cutting neck tissues or cutting major blood vessels initiates the mechanisms responsible for electroencephalographic (EEG) responses to slaughter by ventral-neck incision without prior stunning in halothane-anaesthetised calves.

METHODS: Calves were assigned to two groups, viz transection of neck tissues with intact blood circulation through the brain (n=10), or transection of the major blood vessels of the neck but not most other neck tissues (n=7). They were minimally anaesthetised with halothane, using an established anaesthesia protocol. The animals in the neck-tissue transection group had their carotid arteries and jugular veins exposed and cannulated proximal and distal to the proposed site of subsequent ventral-neck incision; this diverted blood fl ow through these vessels so that cerebral perfusion and drainage were preserved. In animals in the blood-vessel transection group, the carotid arteries and jugular veins were exposed bilaterally by surgical dissection. They were then transected without further damage to the remaining structures of the neck. Changes in the median frequency (F50), 95% spectral edge frequency (F95), total power of the EEG (Ptot), and arterial blood pressure were compared within each group before and after neck-tissue or blood-vessel transection, and between groups following treatments.

RESULTS: Neck-tissue transection resulted in little overall change in the F50, an increase in the F95, and an initial increase in Ptot followed by a transient decrease and eventual return to pre-treatment values. There was between-animal variation in these EEG parameters. Transection of the major blood vessels of the neck resulted in a decrease in F50 in most animals; changes in F95 were highly variable, and there was a decrease in Ptot.

CONCLUSIONS: The EEG responses seen following necktissue and blood-vessel transection were qualitatively distinct, and suggested that cutting neck tissues caused greater noxious sensory input than transection of only the major blood vessels of the neck. These observations support the conclusion that the EEG responses seen after ventral-neck incision in intact animals are primarily due to noxious stimulation as a result of incision of ventral-neck tissues and not mainly as a result of loss of blood flow through the brain.