Use of computed tomography adrenal gland measurement for differentiating ACTH dependence from ACTH independence in 64 dogs with hyperadenocorticism

Background: The measurement of adrenal gland size on computed tomography (CT) scan has been proposed for the etiological diagnosis of hyperadrenocorticism (HAC) in dogs. Symmetric adrenal glands are considered to provide evidence for ACTH‐dependent hyperadrenocorticism (ADHAC), whereas asymmetry suggests ACTH‐independent hyperadrenocorticism (AIHAC). However, there are currently no validated criteria for such differentiation. Objective: The aim of this retrospective study was to compare various adrenal CT scan measurements and the derived ratios in ADHAC and AIHAC cases, and to validate criteria for distinguishing between these conditions in a large cohort of dogs. Animals: Sixty‐four dogs with HAC (46 ADHAC, 18 AIHAC). Methods: Dogs with confirmed HAC and unequivocal characterization of its origin were included. Linear measurements of adrenal glands were made on both cross‐sectional and reformatted images. Results: An overlap was systematically observed between the AIHAC and ADHAC groups for all measurements tested. Overlaps also were observed for ratios tested. For the maximum adrenal diameter ratio derived from reformatted images (rADR), only 1/18 AIHAC dogs had a rADR within the range for ADHAC. For a threshold of 2.08, the 95% confidence intervals for estimated sensitivity and specificity extended from 0.815 to 1.000 and from 0.885 to 0.999, respectively, for AIHAC diagnosis. Conclusion and Clinical Importance: Measurements from cross‐sectional or reformatted CT scans are of little use for determining the origin of HAC. However, rADR appears to distinguish accurately between ADHAC and AIHAC, with a rADR > 2.08 highly suggestive of AIHAC.     

Postanesthetic equine myopathy suggestive of malignant hyperthermia. A case report

Signs of malignant hyperthermia, including progressive increases in PaCO2, skin temperature and heart rate, and elevated serum levels of potassium, inorganic phosphate, and creatine kinase, were identified in a halothane-anesthetized horse. Treatment was discontinuing halothane administration, applying ice and cold fluids, and hyperventilating with 100% oxygen. After an initial recovery, bilateral hindlimb myopathy and pigmenturia developed. The myopathy resolved after treatment with oral dantrolene, IV fluids, and hydrocortisone. Results of caffeine-halothane challenge, using semimembranosus muscle collected 2 weeks after the episode, were considered within normal limits for horses. The intraoperative abnormalities were evidently predictive of postanesthetic myopathy but the cause in this horse remained unclear.     

RNA required for import of precursor proteins into mitochondria

A cytoplasmic RNA moiety is necessary for posttranslational uptake of nuclear-encoded mammalian proteins destined for the mitochondrial matrix. Post-translational addition of ribonuclease to a reticulocyte lysate-programmed cell-free translation mixture inhibited subsequent import of six different mitochondrial matrix enzyme precursors into rat liver mitochondria. The required RNA is highly protected, as indicated by the high concentrations of ribonuclease necessary to produce this inhibition. The dependence of the inhibitory effect on temperature, duration of exposure to ribonuclease, and availability of divalent cations is characteristic of the nuclease susceptibility of ribonucleoproteins. The ribonuclease-sensitive component was found in a 400-kilodalton fraction which contains the mitochondrial protein precursors.     

Response of calves to challenge exposure with virulent bovine respiratory syncytial virus following intranasal administration of vaccines formulated for parenteral administration

OBJECTIVE: To determine whether single-fraction and combination modified-live bovine respiratory syncytial virus (BRSV) vaccines commercially licensed for parenteral administration could stimulate protective immunity in calves after intranasal administration. DESIGN: Randomized controlled trial. ANIMALS: 39 calves. PROCEDURES: Calves were separated from dams at birth, fed colostrum with a minimal concentration of antibodies against BRSV, and maintained in isolation. In 2 preliminary experiments, 9-week-old calves received 1 (n = 3) or 2 (3) doses of a single-component, modified-live BRSV vaccine or no vaccine (8 control calves in each experiment), and were challenged with BRSV 21 days after vaccination. In a third experiment, 2-week-old calves received combination modified-live virus (MLV) vaccines with or without BRSV and calves were challenged with BRSV 8 days later. Calves were euthanized, and lung lesions were measured. Immune responses, including serum and nasal antibody and nasal interferon-alpha concentrations, were assessed. RESULTS: BRSV challenge induced signs of severe clinical respiratory tract disease, including death and pulmonary lesions in unvaccinated calves and in calves that received a combination viral vaccine without BRSV. Pulmonary lesions were significantly less severe in BRSV-challenged calves that received single or combination BRSV vaccines. The proportion of calves that shed virus and the peak virus titer was decreased, compared with control calves. Protection was associated with mucosal IgA antibody responses after challenge. CONCLUSIONS AND CLINICAL RELEVANCE: Single and combination BRSV vaccines administered intranasally provided clinical protection and sparing of pulmonary tissue similar to that detected in response to parenteral delivery of combination MLV and inactivated BRSV vaccines previously assessed in the same challenge model.     

Galactosyl diglycerides: their possible function in Euglena chloroplasts

Illumination of euglenas grown in the dark induces the formation of chloroplasts characterized by the simultaneous appearance of chlorophyll and galactosyl diglycerides in a relatively fixed ratio. The fatty acyl chains of the galactosyl diglycerides are constructed so that they can provide a stable lock-and-key fit with the phytol chains of chlorophyll in such a way as to localize the porphyrin structures of chlorophyll and space them for efficient photoreception. Light-starved photobiotic euglenas show chloroplast shrinkage with a concurrent partial loss of galactosyl diglycerides.     

Further comparison of faecal egg count reduction test procedures: Sensitivity and specificity

Extract

In a recent communication (McKenna2006 McKenna, PB. 2006. A comparison of faecal egg count reduction test procedures. New Zealand Veterinary Journal, 54: 202–3. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]), a comparison was made between four different methods for calculating results from faecal egg count reduction (FECR) tests (FECRTs). The first and most complex of these, referred to as FECRT₁, involved the use of the formula: FECR = 100 × (1?[T2/T1][C1/C2]), where T1 and T2 represented the mean pre- and post-treatment faecal nematode egg counts (FECs) of a treated group, and C1 and C2 represented the mean pre- and post-treatment FECs of an untreated control group, respectively. The other three formulae consisted of more simplified versions of this procedure. In one of them (FECRT₂), only post-treatment samples were considered, whereas the other two were based on comparisons between the FECs of groups of animals sampled at the time of anthelmintic treatment (pre-treatment) with those sampled several days later (post-treatment). Thus, FECRT₂ was determined according to the formula: FECR = 100 × (1?[T2/C2]), while FECRT₃ was calculated from FECR = 100 × (1?[T2/T1]). The fourth procedure (FECRT₄) was based on a further simplification of FECRT₃ where pre-treatment FECs from only one treatment group were used for comparison with all post-treatment results. This base-line pre-treatment group thus effectively functioned as an untreated control group and hence the formula for FECRT₄ was FECR = 100 × (1?[T2/C1]).     

Resistance to moxidectin and abamectin in naturally acquired Ostertagia circumcincta infections in sheep

AIM: To investigate the occurrence of resistance to macrocylic lactone (ML) anthelmintics by Ostertagia circumcincta in lambs on a sheep and cattle property in the North Island of New Zea- land.

METHODS: Thirty lambs were randomly allocated to one of five equal-sized groups, consisting of an untreated control and four treatment groups. The treatments, which were administered at the manufacturer's recommended dose rates, included oral moxidectin, oral abamectin (both at 0.2 mg/kg), an albendazole-levamisole combination, and an albendazole-levamisole-ivermectin combination. Post mortem worm counts were undertaken 7 days after treatment to determine the efficacy of each anthelmintic.

RESULTS: The albendazole-levamisole and albendazole-levam-isole-ivermectin combinations both reduced O. circumcincta burdens to zero whereas for moxidectin and abamectin efficacies of only 72% and 29%, respectively, were recorded.

CONCLUSIONS: These results clearly demonstrated the occurrence of resistance to MLs by O. circumcincta. Although this is not the first occasion where resistance to this anthelmintic family has been detected in this parasite in sheep in New Zealand, it is the first instance that resistance to either moxidectin or abamectin has been reported.     

Complex dynamics may limit prediction in marine fisheries

Complex nonlinear dynamics in marine fisheries create challenges for prediction and management, yet the extent to which they occur in fisheries is not well known. Using nonlinear forecasting models, we analysed over 200 time series of survey abundance and landings from two distinct ecosystems for patterns of dynamic complexity (dimensionality and nonlinear dynamics) and predictability. Differences in system dimensionality and nonlinear dynamics were associated with time series that reflected human intervention via fishing effort, implying the coupling between human and natural systems generated dynamics distinct from those detected in the natural resource subsystem alone. Estimated dimensionality was highest for landings and higher in abundance indices of unfished species than fished species. Fished species were more likely to display nonlinear dynamics than unfished species, and landings were significantly less predictable than abundance indices. Results were robust to variation in life history characteristics. Dynamics were predictable over a 1‐year time horizon in seventy percent of time series, but predictability declined exponentially over a 5‐year horizon. The ability to make predictions in fisheries systems is therefore extremely limited. To our knowledge, this is the first cross‐system comparative study, and the first at the scale of individual species, to analyse empirically the dynamic complexity observed in fisheries data and to quantify predictability broadly. We outline one application of short‐term forecasts to a precautionary approach to fisheries management that could improve how uncertainty and forecast error are incorporated into assessment through catch limit buffers.     

Micellization of bovine beta-casein studied by isothermal titration microcalorimetry and cryogenic transmission electron microscopy

The association behavior, critical micellization concentration (CMC), and enthalpy of demicellization (DeltaHdemic) of bovine beta-casein were studied, for the first time by isothermal titration calorimetry, in a pH 7.0 phosphate buffer with 0.1 ionic strength and in pure water. In the buffer solutions, the CMC decreased asymptotically from 0.15 to 0.006 mM as the temperature was raised from 16 to 45 degrees C. DeltaHdemic decreased with increasing temperature between 16 and 28 degrees C but increased from 28 to 45 degrees C. Thermodynamic analysis below 30 degrees C is consistent with the Kegeles shell model, which suggests a stepwise association process. At higher temperatures, this model exhibits limitations, and the micellization becomes much more cooperative. The CMC values in water, measured between 17 and 28 degrees C, decreased with increasing temperature and, expectedly, were higher than those found in the buffer solutions. beta-Casein micelles were visualized and characterized, for the first time in their hydrated state, using advanced digital-imaging cryogenic transmission electron microscopy. The images revealed small, oblate micelles, about approximately 13 nm in diameter. The micelles shape and dimensions remained nearly constant in the temperature range of 24-35 degrees C.