Cryptic Patterning of Avian Skin Confers a Developmental Facility for Loss of Neck Feathering

Vertebrate skin is characterized by its patterned array of appendages, whether feathers, hairs, or scales. In avian skin the distribution of feathers occurs on two distinct spatial levels. Grouping of feathers within discrete tracts, with bare skin lying between the tracts, is termed the macropattern, while the smaller scale periodic spacing between individual feathers is referred to as the micropattern. The degree of integration between the patterning mechanisms that operate on these two scales during development and the mechanisms underlying the remarkable evolvability of skin macropatterns are unknown. A striking example of macropattern variation is the convergent loss of neck feathering in multiple species, a trait associated with heat tolerance in both wild and domestic birds. In chicken, a mutation called Naked neck is characterized by a reduction of body feathering and completely bare neck. Here we perform genetic fine mapping of the causative region and identify a large insertion associated with the Naked neck trait. A strong candidate gene in the critical interval, BMP12/GDF7, displays markedly elevated expression in Naked neck embryonic skin due to a cis-regulatory effect of the causative mutation. BMP family members inhibit embryonic feather formation by acting in a reaction-diffusion mechanism, and we find that selective production of retinoic acid by neck skin potentiates BMP signaling, making neck skin more sensitive than body skin to suppression of feather development. This selective production of retinoic acid by neck skin constitutes a cryptic pattern as its effects on feathering are not revealed until gross BMP levels are altered. This developmental modularity of neck and body skin allows simple quantitative changes in BMP levels to produce a sparsely feathered or bare neck while maintaining robust feather patterning on the body

[Failure to characterize a suprarenal metastasis of hepatocarcinoma using the percentage of contrast medium washout with CT: a case study]

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Serious complication of radiofrequency treatment of inoperable bronchial carcinoma

INTRODUCTION: Surgery remains the only curative treatment for primary non-small cell bronchial carcinoma. It is mainly appropriate for small, localised tumours. Some patients have contra-indications to surgery and radiofrequency offers a minimally invasive alternative with few complications. It is performed under general anaesthesia by a percutaneous approach. The main complications are mechanical, primarily pneumothorax, and infections are uncommon and generally mild. CASE REPORT: We report the case of a man treated by radiofrequency for a small bronchial carcinoma. The procedure was rapidly complicated by infection of the area treated, spreading throughout both lung fields and requiring intensive and prolonged antibiotic treatment. Resolution of the infection was slow despite appropriate treatment. The rapid onset and spread are explained by the immunosuppressed state of the patient. CONCLUSION: Radiofrequency is a recent treatment for bronchial carcinoma that is developing rapidly. Though it is associated with low morbidity and mortality the possibility of potentially fatal infective complications in certain patients should be recognised