Caprine abscess model of tulathromycin concentrations in interstitial fluid from tissue chambers inoculated with Corynebacterium pseudotuberculosis following subcutaneous or intrachamber administration.

Corynebacterium pseudotuberculosis causes chronic, suppurative, abscessing conditions in livestock and humans. We used an in vivo model to evaluate antimicrobial efficacy for focal abscesses caused by C. pseudotuberculosis. Tissue chambers were surgically implanted in the subcutaneous tissues of the right and left paralumbar fossa of 12 goats to serve as a model for isolated, focal abscesses. For each goat, one tissue chamber was inoculated with C. pseudotuberculosis, while the contralateral chamber served as an uninoculated control. Six goats were administered a single dose of tulathromycin at 2.5 mg/kg of body weight subcutaneously, while the other six received the same dose by injection directly into the inoculated chambers. Our objective was to compare the effects and tulathromycin concentrations in interstitial fluid (IF) samples collected from C. pseudotuberculosis-infected and control chambers following subcutaneous or intrachamber injection of tulathromycin. In addition, the effects of tulathromycin on the quantity of C. pseudotuberculosis reisolated from inoculated chambers were assessed over time. Tulathromycin IF concentrations from C. pseudotuberculosis-infected and control tissue chambers were similar to those in plasma following subcutaneous administration. Following intrachamber administration, tulathromycin IF concentrations in infected chambers were continuously above the MIC for the C. pseudotuberculosis isolate for 15 days. There were no significant differences for plasma area under the curve and elimination half-lives between subcutaneous and intrachamber administration. Six of the 12 infected chambers had no growth of C. pseudotuberculosis 15 days postadministration. Results of this study indicate that tulathromycin may be beneficial in the treatment of focal infections such as those caused by C. pseudotuberculosis.

Neurological disease in lambs associated with exposure to high environmental temperature and humidity.

BACKGROUND: We detected a pattern of lambs presenting with hyperthermia and neurological signs during the summer. OBJECTIVES: The main objectives of this study were to compare clinical findings and results of diagnostic testing and to identify a potential etiology. ANIMALS: Fifteen clinical cases of lambs less than 12 months of age presenting with neurological signs, tachypnea, and hyperthermia over 4 summers. METHODS: Retrospective case series. Medical records were searched for lambs less than 12 months of age that presented with neurological signs including the following: kyphosis, pelvic limb hyperextension, treading of feet, muscle tremors and recumbency, and hyperthermia of greater than 104°F. A grading system was established to describe severity of presenting neurological signs. Weather data were collected from weather stations near the farm of origin for 3 days prior to presentation. RESULTS: The lambs were from 7 flocks in central Texas. All cases occurred between July and September, with a median heat index of 90.5 for the 3 days before presentation. Complete blood count, serum chemistry, necropsy examination, rumen content, virology, brain MRI, liver copper, selenium, and vitamin E failed to identify a consistent etiology for the signs presented. The only common factor was high heat and humidity. Histopathological examination identified axonal degeneration and skeletal muscle necrosis in some lambs. CONCLUSIONS AND CLINICAL IMPORTANCE: These clinical cases appeared similar to the Australian disease humpyback and indicate that lambs exposed to high environmental temperatures and humidity might be at risk of developing the described clinical presentation.

Pore characterization through propagator-resolved transverse relaxation exchange.

We use the propagator-resolved transverse relaxation exchange experiment to characterize the pore space and fluid behavior of water saturated, tight-packed quartz sand. The experiment uses T2 exchange plots to observe the number of molecules that shift their environment for a range of mixing times. The propagator dimension allows us to determine how far the molecules have moved. The peak intensities are integrated and then plotted as a function of displacement and mixing time. We also model our system using both a probabilistic pore-hopping simulation and a spreading Gaussian model. We use the results of these simulations to interpret the peak intensity plots. From this, we can estimate pore features such as characteristic time, pore radii, and interpore spacing. The tortuosity of the different pore sizes can then be calculated from these values.

The dependence on magnetic field strength of correlated internal gradient relaxation time distributions in heterogeneous materials.

Magnetic susceptibility differences in porous media produce local gradients within the pore space. At high magnetic fields, these inhomogeneities have the potential to greatly affect nuclear magnetic resonance measurements. We undertake a study using a new NMR technique to measure the internal gradients present in highly heterogeneous samples over a wide range of magnetic field strengths. Our results show that even at ultra-high fields there can exist signal at internal gradient strengths sufficiently small that techniques for suppressing unwanted side effects have the possibility to be used. Our findings encourage the use of these high and ultra-high field strengths for a broader range of samples. Our results also give experimental evidence to support the theory of internal gradient scaling as a function of field strength within pores.

Propagator resolved transverse relaxation exchange spectroscopy.

We present in this communication a novel propagator-resolved transverse relaxation exchange experiment. This experiment enhances the previous technique of transverse relaxation exchange by enabling spatial resolution. Hence, we are able to obtain separate, and remarkably different, T2-T2 exchange plots, corresponding to different spatial displacement of the spin bearing water molecules in a porous sand matrix. This experiment is the first to combine two inverse Laplace dimensions with a Fourier dimension, opening the door to a host of new experiments combining Fourier and inverse Laplace spectroscopy.

Tracking pore to pore exchange using relaxation exchange spectroscopy.

We observe the movement of water over time between pores of differing sizes in Castlegate sandstone. To achieve this, we perform an NMR transverse relaxation exchange experiment for several mixing times. The resulting data are converted to 2D T2 distributions using a 2D inverse Laplace transform (ILT). We show for the first time that quantitative analysis of ILT distributions enables one to extract characteristic times for different pores sizes. This information is potentially useful for permeability determination as well as better understanding of exchange between specific pore subpopulations.

A familial peripheral neuropathy and glomerulopathy in Gelbvieh calves.

Nine Gelbvieh calves originating in four herds and clinically presenting with rear limb ataxia/paresis had histopathologically confirmed peripheral neuropathy and a proliferative glomerulopathy. Degenerative lesions were severe in peripheral nerves, dorsal and ventral spinal nerve roots, and less marked in dorsal fasciculi of the spinal cord. Cell bodies of spinal ganglia were minimally diseased; ventral horn neurons occasionally had central chromatolysis and nuclear displacement. Glomerular lesions ranged from mild mesangial hypercellularity to glomerulosclerosis. Pedigree analysis of affected animals from one herd indicated a strong familial relationship and probable hereditary basis for the syndrome.

Laser lithotripsy of a urethral calculus via ischial urethrotomy in a steer.

A steer examined because of obstructive urolithiasis and urethral rupture underwent laser lithotripsy, using a chromium-thulium-holmium:yttrium-aluminum-garnet (Ho:YAG) laser inserted through an ischial urethrotomy. Procedures were performed with caudal epidural anesthesia. Six months after surgery, the urethra was patent with no clinical evidence of urethral stricture or fistula. Ischial urethrotomy provided rapid access to the bladder for catheterization and to the obstructive urolith for lithotripsy. Laser lithotripsy was a rapid and effective means of urolith removal in this steer.