Rapid development of application-specific flexible MRI receive coils.

Over the last 30 years, there have been dramatic changes in phased array coil technology leading to increasing channel density and parallel imaging functionality. Current receiver array coils are rigid and often mismatched to patient's size. Recently there has been a move towards flexible coil technology, which is more conformal to the human anatomy. Despite the advances of so-called flexible surface coil arrays, these coils are still relatively rigid and limited in terms of design conformability, compromising signal-to-noise ratio (SNR) for flexibility, and are not designed for optimum parallel imaging performance. The purpose of this study is to report on the development and characterization of a 15-channel flexible foot and ankle coil, rapidly designed and constructed using highly decoupled radio-frequency (RF) coil elements. Coil performance was evaluated by performing SNR and g-factor measurements. In vivo testing was performed in a healthy volunteer using both the 15-channel coil and a commercially available 8-channel foot coil. The highly decoupled elements used in this design allow for extremely rapid development and prototyping of application-specific coils for different patient sizes (adult vs child) with minimal additional design consideration in terms of coil overlap and geometry. Image quality was comparable to a commercially available RF coil.

Soft tissue sarcoma in a short-beaked echidna (Tachyglossus aculeatus).

CASE REPORT: An adult male short-beaked echidna in poor body condition was found with a 25 × 12 mm round, ulcerated and bleeding mass on the left side of the face at the base of the beak. The animal responded well to initial supportive care and was referred to a specialist wildlife centre for further assessment and treatment. Clinical pathology showed moderate neutrophilia, mild anaemia, mild elevation in liver enzymes (ALT, AST and ALP) and mild azotaemia. Initial clinical differential diagnoses for the facial mass favoured an inflammatory rather than a neoplastic lesion, based on previous reports. Examination of an incisional biopsy identified a malignant spindle cell proliferation (sarcoma) not amenable to complete surgical excision. The animal was euthanased on humane grounds. Immunohistochemical assessment of the mass showed it to be negative for cytokeratin, desmin, smooth muscle actin, periaxin and MAC387 antibody labelling. Definitive histogenesis was undetermined and a final diagnosis of poorly differentiated sarcoma, unlikely to be of muscle, Schwann cell or histiocytic origin, was made. CONCLUSION: Reports of neoplasia in prototherian mammals (monotremes) are rare. To the authors' knowledge this is the first report of such a tumour in a monotreme species and the first immunohistochemical characterisation of a stromal tumour in these animals. The malignant nature of this tumour contrasts with a previous report of benign neoplasia (fibroma) associated with the beak. Although rare, malignant neoplasia should be included in the differential diagnoses of mass lesions in monotremes, despite inflammatory or traumatic mass lesions being more commonly reported.

Severe subacute necrotizing encephalopathy (Leigh-like syndrome) in American Staffordshire bull terrier dogs.

Seventeen American Staffordshire bull terrier puppies, 6-8 weeks of age, from seven closely related litters, presented with rapidly progressive central vestibular neurological signs. Previously reported hereditary ataxias in the breed, including l-2 hydroxyglutaric aciduria and cerebellar cortical degeneration, as well as thiamine deficiency, were excluded. Elevated lactate levels and lactate:pyruvate ratios gave supporting evidence of a defect of the respiratory chain or Leigh-like syndrome. Histopathology in all cases showed a bilaterally symmetrical necrotizing encephalopathy, with malacia of the neuropil centred on the vestibular and olivary nuclei of the brainstem. This is the first documentation of a heritable rapidly progressive lethal necrotizing encephalopathy consistent with Leigh-like syndrome, in American Staffordshire bull terrier dogs.

Severe systemic hypertension in a cat with pituitary-dependent hyperadrenocorticism.

A seven-year-old Burmese cat was presented with sudden onset blindness. On physical examination, the cat had bilateral retinal detachment and severe systemic hypertension. Further clinical investigations revealed pituitary-dependent hyperadrenocorticism. Antihypertensive therapy was discontinued when the hypertension resolved after bilateral adrenalectomy. Systolic blood pressure remained normal until 19 months post-operatively when systemic hypertension recurred and was attributed to chronic kidney disease. The cat was euthanased 47 months after initial presentation. A pituitary adenoma was identified at post-mortem examination. This case illustrates that systemic hypertension can occur secondary to hyperadrenocorticism in the cat.

Properties of nucleosomes in acetylated mouse mammary tumor virus versus 5S arrays.

Acetylation is one of the most abundant histone modifications found in nucleosomes. Although such modifications are thought to function mainly in recognition, acetylation is known to produce nucleosome structural alterations. These could be of functional significance in vivo. Here, the basic features of mouse mammary tumor virus (MMTV) promoter nucleosomal arrays reconstituted with highly acetylated histones prepared from butyrate-treated HeLa cells are characterized by atomic force microscopy. Results are compared to previous results obtained with hypoacetylated MMTV and hyper- or hypoacetylated 5S rDNA arrays. MMTV arrays containing highly acetylated histones show diminished intramolecular compaction compared to hypoacetylated MMTV arrays and no tendency for cooperativity in nucleosome occupation. Both features have been suggested to reflect histone tail-mediated internucleosomal interactions; these observations are consistent with that suggestion. 5S arrays show qualitatively similar behavior. Two other effects of acetylation show stronger DNA template dependence. Nucleosome salt stability is diminished in highly acetylated compared to hypoacetylated MMTV arrays, but nucleosome (histone) loading tendencies are unaffected by acetylation. However, highly acetylated histones show reduced loading tendencies on 5S templates (vs hypoacetylated), but 5S nucleosome salt stabilities are unaffected by acetylation. ATP-dependent nucleosome remodeling by human Swi-Snf is similar on hyper- and hypoacetylated MMTV arrays.