Atresia de coana bilateral en adulto con malformación craneofacial asociada: un diagnóstico poco habitual / Bilateral choanal atresia in adult with associated craneofacial malformation: an unusual diagnosis

La atresia de coana es una rara malformación congénita improbable de encontrar de forma bilateral en un adolescente o adulto. Hasta la fecha, no se ha descrito ningún caso de atresia bilateral en un adulto con una malformación asociada de cabeza y cuello que haya requerido tratamiento conjunto. El tratamiento de elección de la atresia de coana bilateral continúa siendo la cirugía endoscópica, con controversia en el uso intraoperatorio de mitomicina o la colocación de stents para evitar estenosis. Lo que no está claro es el orden de tratamiento y la simultaneidad del procedimiento si se asocian otras posibles patologías que tengan una indicación quirúrgica. Presentamos un caso clínico que cumple con todos estos requisitos.

Choanal atresia is a rare congenital malformation that is unlikely to be found bilaterally and is seldom diagnosed in adulthood. To date, no clinical case of bilateral atresia has been described with a head and neck malformation that requires surgical treatment in an adult. The preferred treatment is still endoscopic sinonasal surgery with discrepancies of the use or not of intraoperative topical mitomycin or the placement of stents to avoid restenosis. What is not clear is the order of treatment and simultaneity of the procedure with other possible associated pathologies that have a surgical indication. We present a clinical case that meets all these requirements.

The heat shock cognate protein hsc73 assembles with A(1) adenosine receptors to form functional modules in the cell membrane.

A(1) adenosine receptors (A(1)Rs) are G protein-coupled heptaspanning receptors that interact at the outer face of the plasma membrane with cell surface ecto-adenosine deaminase (ecto-ADA). By affinity chromatography the heat shock cognate protein hsc73 was identified as a cytosolic component able to interact with the third intracellular loop of the receptor. As demonstrated by surface plasmon resonance, purified A(1)Rs interact specifically with hsc73 with a dissociation constant in the nanomolar range (0.5 +/- 0.1 nM). The interaction between hsc73 and A(1)R led to a marked reduction in the binding of the ligands and prevented activation of G proteins, as deduced from (35)S-labeled guanosine-5'-O-(3-thio)triphosphate binding assays. Interestingly this effect was stronger than that exerted by guanine nucleotide analogs, which uncouple receptors from G proteins, and was completely prevented by ADA. As assessed by immunoprecipitation a high percentage of A(1)Rs in cell lysates are coupled to hsc73. A relatively high level of colocalization between A(1)R and hsc73 was detected in DDT(1)MF-2 cells by means of confocal microscopy, and no similar results were obtained for other G protein-coupled receptors. Colocalization between hsc73 and A(1)R was detected in specific regions of rat cerebellum and in the body of cortical neurons but not in dendrites or synapses. Remarkably, agonist-induced receptor internalization leads to the endocytosis of A(1)Rs by two qualitatively different vesicle types, one in which A(1)R and hsc73 colocalize and another in which hsc73 is absent. These results open the interesting possibility that signaling via G protein-coupled receptors may be regulated by heat shock proteins.