Neuroimmune connections in ovine pharyngeal tonsil: potential site for prion neuroinvasion

in Cell & Tissue Research (2012)

Recent studies have proved the possible implication of nasal associated lymphoid tissues, mainly the pharyngeal tonsil, in prion pathogenesis. However, the mechanisms of this neuroinvasion are still being ... [more ▼]

Recent studies have proved the possible implication of nasal associated lymphoid tissues, mainly the pharyngeal tonsil, in prion pathogenesis. However, the mechanisms of this neuroinvasion are still being debated. To determine the potential sites for prion neuroinvasion inside the ovine pharyngeal tonsil, the topography of neurofilaments heavy (200 kDa) (NFH), neurofilaments light (70 kDa) (NFL) and glial fibrillar acidic protein (GFAP) was semi-quantitatively analysed inside the different compartments of the tonsil. The results showed that the most innervated areas were the interfollicular area and the connective tissue located beneath the respiratory epithelium. Even if the germinal centre of the lymphoid follicles was poorly innervated, the existence of rare follicular dendritic cell-nerve synapses inside the germinal centre indicates that this mechanism of neuroinvasion is possible but unlikely to be unique. The host PRNP genotype did not influence the pattern of innervation in these different tonsil compartments, unlike age: an increase of nerve endings in a zone of high trafficking cells beneath the respiratory epithelium occurred with ageing. A minimal age-related increase of innervation inside the lymphoid follicles was also observed. An increase in nerve fibre density around the lymphoid follicles, in an area rich in mobile cells able to transport PrPd, could ensure a more efficient infectivity, not in the early phase but in the advanced phase of lymphoinvasion after amplification of PrPd, or could act as direct site of entry during neuroinvasion. [less ▲]

Impact of successive freezing-thawing cycles on 3-T magnetic resonance images of the digits of isolated equine limbs

in American Journal of Veterinary Research (2011), 72(6), 780-790

The purpose of this study was to assess the impact of freezing and thawing on MR images of equine feet examined ex vivo. Nine equine cadaver digits were first imaged at room temperature (T0). Among the 9 ... [more ▼]

The purpose of this study was to assess the impact of freezing and thawing on MR images of equine feet examined ex vivo. Nine equine cadaver digits were first imaged at room temperature (T0). Among the 9 digits, 3 (group 1) were imaged in a 3 Tesla MR system after one and after 2 freezing-thawing cycles. Digits of group 1 were thawed in a cold room at 4°C for 36h. Three other digits (group 2) were imaged after one freezing-thawing cycle. Digits of group 2 were thawed in a cold room at 4°C and then rescanned after 24h at room temperature. The last 3 digits (group 3) were scanned after one freezing-thawing cycle. Digits of group 3 were thawed at room temperature for 24h. Sequences used were Spin Echo (SE) T1, Turbo Spin Echo (TSE) T2 and proton density (PD), Short Tau Inversion Recovery (STIR), Double Echo Steady State (DESS), 3D Gradient Echo (GE) T1 and 2D GE T2*. Images obtained on the fresh limbs at room temperature were subjectively compared side by side to images obtained at the different freezing-thawing cycles. A quantitative analysis to assess signal change between examinations was realized by measuring signal to noise ratio (SNR). Visibility and margination of the anatomical structures of the foot and overall image quality were subjectively considered unchanged except for the hoof where the lamina was considered less visible distally after freezing and thawing in the GE T2* and in TSE T2 and PD sequences. Quantitative analysis demonstrated SNR changes in the bone marrow only in the distal phalanx in the SE T1 sequence when the feet were thawed at room temperature. When the feet were thawed in a cold room at 4°C, bone marrow SNR changes were present in the SE T1, GE T1 and TSE PD sequences. Signal changes were significant in the synovial recess when the thawing process was made at 4°C and not when the thawing process was at ambient temperature. The soft tissue structures and the hoof capsule showed significant changes with an increase of SNR, except in STIR, after freezing and thawing at 4°C and at room temperature. SNR changes in the soft tissues were mainly present in GE sequences. [less ▲]

Effect of sampling method and incubation temperature on fungal culture in canine sino-nasal aspergillosis

in Journal of Small Animal Practice (2009), 50(2), 67-72

OBJECTIVES: To evaluate the most appropriate sampling procedure and the effect of incubation temperature on fungal culture in the diagnosis of canine sinonasal aspergillosis (SNA). METHODS: Sixteen dogs ... [more ▼]

OBJECTIVES: To evaluate the most appropriate sampling procedure and the effect of incubation temperature on fungal culture in the diagnosis of canine sinonasal aspergillosis (SNA). METHODS: Sixteen dogs with SNA and 20 dogs with non-fungal nasal disease entered a prospective study. Nasal secretions and mucosal biopsies were collected in all dogs. Fungal plaques were also sampled in dogs with SNA. Each specimen was taken in duplicate from each dog and incubated at room temperature and 37 degrees C. RESULTS: In dogs with SNA, nasal secretions, mucosal biopsies and fungal plaques yielded fungal growth at room temperature in one, one and seven dogs, respectively, whereas fungal growth was obtained at 37 degrees C in three, 12 and 14 dogs, respectively. No specimen collected from any dog with non-fungal nasal disease yielded fungal growth at room temperature or at 37 degrees C. CLINICAL SIGNIFICANCE: The diagnosis of canine SNA is more likely to be confirmed following culture of mucosal biopsies or fungal plaques than nasal secretions sampled blindly with swabs. Incubating cultures at 37 degrees C is more likely to provide a diagnostic outcome than when samples are cultured at room temperature. Fungal culture of nasal specimens has good specificity for the diagnosis of SNA in dogs. [less ▲]