The bovine innate immune response during experimentally-induced Pseudomonas aeruginosa mastitis

Almost half of all clinical cases of mastitis are caused by Gram-negative bacteria. Among these bacteria, intramammary infection by Pseudomonas aeruginosa remains one of the most refractory to antibiotic therapy. The ability to recognize potentially harmful pathogens whether previously encountered or not, as well as the induction of an initial pro-inflammatory response to these pathogens, are critical components of host innate immunity. Although the innate immune response to another Gram-negative mastitis-causing pathogen, Escherichia coli, has been well-characterized, little is known about the response to other Gram-negative bacteria, including P. aeruginosa. The objective of the current study was to characterize the systemic and localized bovine innate immune response to intramammary infection with P. aeruginosa. The contralateral quarters of ten mid-lactating Holstein cows were challenged with either saline or P. aeruginosa. Following the establishment of infection, milk samples were collected and assayed for changes in cytokine and growth factor concentrations, complement activation, and changes in the levels of soluble CD14 (sCD14) and lipopolysaccharide (LPS)-binding protein (LBP), two accessory molecules involved in host recognition of Gram-negative bacteria. Initial increases in milk somatic cell counts were evident within 12h of experimental challenge and remained elevated for >or=3 weeks. Increased permeability of the mammary gland vasculature, as evidenced by elevated milk levels of BSA, was initially observed 20 h post-infection and persisted for 2 weeks. Within 32 h of challenge, increased levels of IL-8, TNF-alpha, IL-10, and IL-12 were detected, however, the elevated levels of these cytokines were not sustained for longer than a 24h period. In contrast, elevations in IL-1beta, IFN-gamma, TGF-alpha, TGF-beta1, TGF-beta2, sCD14, LBP, and activated complement factor 5 (C5a) were sustained for periods of >48 h. Systemic changes were characterized by elevated body temperature, induction of the acute phase protein synthesis of serum amyloid A and LBP, and a transient decrease in circulating neutrophils and lymphocytes. Together, these data demonstrate the capability of the mammary gland to mount a robust innate immune response to P. aeruginosa that is characterized by the induction of pro-inflammatory cytokines, complement activation, and increased levels of accessory molecules involved in Gram-negative bacterial recognition.     

SCINTIGRAPHIC CHARACTERIZATION OF THE EQUINE FOREDIGIT AND METACARPOPHALANGEAL REGION FROM BIRTH TO SIX MONTHS OF AGE

Both foredigits and metacarpophalangeal joints of six Quarter Horse foals were scanned serially to six months of age using ⁹⁹Tc-methylene diphosphonate. Dorsal scans were made on day 1 and at two, four, six, ten, 14, 18, 22 and 26 weeks of age. Scans were assessed visually for distal third metacarpal, proximal phalangeal, and middle phalangeal physeal appearance and closure. Scans were also evaluated by computer region-of-interest (ROI) and line-profile analysis to characterize the physes quantitatively. Physeal region radioactivity relative to a disphyseal reference region was greatest at four weeks for all physes. Scintigraphic physeal closure of all physes occurred at approximately six months of age with a range of four and one half to greater than six months. The study was conducted to allow better assessment of diffuse and focal physeal disease by determining developmental times at which normal physeal region radioactivity has decreased enough to not obscure abnormal radioactivity and by quantifying scintigraphic physeal appearance which enables computer analysis to detect visually indeterminate physeal abnormalities.     

Genetic Variability and Structure of Canadian Populations of the Sapstain Fungus Ceratocystis resinifera

ABSTRACT Genomic DNA was extracted from 129 isolates of Ceratocystis resinifera, a species belonging to the C. coerulescens complex, and 19 polymorphic random amplified polymorphic DNA markers were used to study the population genetic structure of this fungus. The analysis suggested a moderate value for genetic diversity (H(S) = 0.209). However, when monomorphic markers and rare alleles, representing 89 markers, also were included in the calculation, the genetic diversity of Canadian populations of C. resinifera appeared to be much lower (H(S) = 0.045). This could be explained by two hypotheses: (i) recent introduction of this species into North America and (ii) clonal reproduction (by selfing). No specialization by C. resinifera for coniferous tree species was observed based on genetic differentiation index between isolates sampled from Pinus and Picea spp. and on phylogenetic analysis using Dice coefficient of association. In spite of a low genetic diversity, a very high genetic differentiation was observed among the nine geographical populations studied (F(ST) = 20.8%). The genetic differences were especially striking when populations from Eastern Canada were compared with populations from Western Canada (phiST = 0.27%; P < 0.001), suggesting that a geographic reproductive barrier occurs in Central Canada. This barrier may be the consequence of a weak migration of insect vectors of C. resinifera due to reduced presence of hosts in the Canadian Great Plains, where extensive agriculture occurs. However, results from pairwise F(ST) matrix and phylogeny of haplotypes suggest that the barrier is not totally impenetrable because some gene flow occurred from the west and from the east in the Big River (Saskatchewan) population located in the middle of the Great Plains.     

Minimally invasive patent ductus arteriosus occlusion in 5 dogs

OBJECTIVE: To report a technique for minimally invasive occlusion of patent ductus arteriosus (PDA) and outcome in 5 dogs. STUDY DESIGN: Clinical cases. Animals: Five, 4-6-month-old, dogs with PDA. MATERIALS AND METHODS: Titanium ligating clips were used for PDA closure in all dogs. Three dogs had video-enhanced mini-thoracotomy PDA occlusion. Two other dogs had thoracoscopic PDA occlusion using a custom-designed thoracoscopy clip applicator. RESULTS: Thoracoscopic PDA occlusion was successful in both dogs in which it was attempted. Complete PDA closure was achieved in 4 dogs. Three months after surgery, the largest dog had residual ductal flow that hemodynamically was insignificant. CONCLUSIONS: Although technically demanding, minimally invasive PDA occlusion is a safe and reliable technique in dogs. Preoperative measurement of the diameter of the PDA is crucial to determine if complete closure with metal clips can be achieved. CLINICAL RELEVANCE: Minimally invasive PDA occlusion should be considered as an alternative to occlusion via conventional thoracotomy.     

Optical spectroscopy of individual single-walled carbon nanotubes of defined chiral structure

We simultaneously determined the physical structure and optical transition energies of individual single-walled carbon nanotubes by combining electron diffraction with Rayleigh scattering spectroscopy. These results test fundamental features of the excited electronic states of carbon nanotubes. We directly verified the systematic changes in transition energies of semiconducting nanotubes as a function of their chirality and observed predicted energy splittings of optical transitions in metallic nanotubes.     

Infrared spectroscopy of comet 81P/Wild 2 samples returned by Stardust

Infrared spectra of material captured from comet 81P/Wild 2 by the Stardust spacecraft reveal indigenous aliphatic hydrocarbons similar to those in interplanetary dust particles thought to be derived from comets, but with longer chain lengths than those observed in the diffuse interstellar medium. Similarly, the Stardust samples contain abundant amorphous silicates in addition to crystalline silicates such as olivine and pyroxene. The presence of crystalline silicates in Wild 2 is consistent with mixing of solar system and interstellar matter. No hydrous silicates or carbonate minerals were detected, which suggests a lack of aqueous processing of Wild 2 dust.