Aportes de la microscopía electrónica de transmisión al diagnóstico de la disquinesia ciliar / Diagnosis of ciliary dyskinesia by electronic microscopy

La disquinesia ciliar primaria es una enfermedad congénita que aúna un grupo heterogéneo de condiciones patológicas que se caracterizan por la presencia de alteraciones microanatómicas o funcionales, o ambas, en las cilias y los flagelos espermáticos. Las manifestaciones clínicas de este desorden son variadas y se caracterizan por la aparición temprana de infección recurrente de las vías auditivo-respiratorias. Además de los determinantes genéticos, la propia infección e inflamación recurrente -así como algunos agentes ambientales- pueden provocar alteraciones ciliares. Estas alteraciones son, sin embargo, de tipo inespecífico y conducen a la llamada disquinesia ciliar secundaria. En el presente trabajo se describen los resultados obtenidos del estudio de 40 biopsias de mucosa nasal y bronquial provenientes de 33 pacientes sospechosos de portar alguna de estas formas de disquinesia ciliar, las cuales fueron remitidas por los médicos tratantes al Laboratorio de Biología Celular del Instituto de Investigaciones Biológicas Clemente Estable para su estudio ppor microscopía electrónica de transmisión. En su conjunto estos estudios mostraron que 9 de los pacientes (27 por ciento) presentaban alteraciones ultra estructurales ciliares compatibles con el diagnóstico de disquinesia ciliar primaria. Tres de ellos tenían situs inversus totalis. El 52 por ciento de los pacientes presentó alteraciones ciliares secundarias. A pesar de sus manifestaciones clínicas, 21 por ciento de los pacientes restantes mostró una ultraestructura ciliar normal. En su conjunto, los resultados obtenidos en la población estudiada apuntan a confirmar la alta frecuencia con que se presentan las alteraciones ciliares en los pacientes respiratorios crónicos. Teniendo en cuenta que el diagnóstico precoz de esta enfermedad es esencial para prevenir el desarrollo de lesiones respiratorias irreversibles, se destaca la importancia de indicar el examen ultraestructural de las cilias en los pacientes portadores de situs inversus y sus hermanos, así como en los individuos afectados de enfermedad respiratoria crónica severa de inicio precoz y carentes de diagnóstico etiológico.

Plasticity in developing rat uterine sensory nerves: the role of NGF and TrkA.

In the present study we investigated the effects of infantile/prepubertal chronic oestrogen treatment, chemical sympathectomy with guanethidine and combined sympathectomy and chronic oestrogen treatment on developing sensory nerves of the rat uterus. Changes in sensory innervation were assessed quantitatively on uterine cryostat tissue sections stained for calcitonin gene-related peptide (CGRP). Uterine levels of NGF protein, using immunohistochemistry and ELISA, and mRNA, using Northern blots and in situ hybridization, were also measured. Finally, levels of TrkA NGF receptor in sensory neurons of T13 and L1 dorsal root ganglia (DRG), which supply the uterus, were assessed using densitometric immunohistochemistry. These studies showed that: (1) chronic oestrogen treatment led to an 83% reduction in the intercept density of CGRP-immunoreactive nerves; (2) sympathectomy had no effect on the density of uterine sensory nerves or on the pattern of oestrogen-induced changes; (3) NGF mRNA and protein increased following sympathectomy or chronic oestrogen treatment; and (4) oestrogen produced increased intensity of labelling (28%) for TrkA receptors in small-diameter sensory neurons, but decreased labelling (13%) in medium-sized neurons, which represent the large majority of the DRG neurons supplying the upper part of the uterine horn. Contrary to expectations, increased levels of NGF after sympathectomy and oestrogen treatment did not lead to increased sensory innervation of the uterus. The possibility that alterations in neuronal levels of TrkA contribute to the lack of response of uterine sensory nerves to the oestrogen-induced increase in NGF levels is discussed.

The oestrogenized rat myometrium inhibits organotypic sympathetic reinnervation.

Chronic administration of oestrogen to rats during the infantile/prepubertal period provokes, at 28 days of age, complete loss of noradrenaline-labelled intrauterine sympathetic nerves. It is not known whether oestrogen inhibits the growth or causes the degeneration of developing uterine sympathetic nerves, or whether the uterus recovers its innervation following cessation of infantile/prepubertal oestrogen treatment. In the present study, we analysed the time-course of the effects of oestrogen on the development of uterine sympathetic nerves in the rat, using histochemical methods. In addition, the pattern of sympathetic reinnervation of the uterus of intact and ovariectomised females was assessed 3 and 6 months after cessation of chronic oestrogen treatment. The ability of sympathetic nerves to reinnervate the oestrogenized uterine tissue was assessed in intraocular transplants of uterine myometrium into ovariectomised host rats. Early exposure to oestrogen did not inhibit the approach of sympathetic nerves to the uterus, but prevented the normal growth and maturation of intrauterine sympathetic fibres and abolished the innervation that reached the organ before initiation of treatment. Three or six months following cessation of oestrogen treatment, most of the sympathetic nerves were restricted to the mesometrium and mesometrial entrance, whereas intrauterine innervation remained persistently depressed as a consequence of a sustained oestrous-like state provoked by ovarian dysfunction (polycystic ovary). An organotypic regrowth of uterine sympathetic nerves was observed in ovariectomised infantile/prepubertal oestrogen-treated animals. After 5 weeks in oculo, the innervation of oestrogenized myometrial transplants was reduced by 50%, and substantial changes in the pattern of reinnervation were observed. In control transplants, 86% of the nerves were terminal varicose myometrial and perivascular nerve fibres, whereas 14% were preterminal nerve bundles. In oestrogenized myometrial transplants, 83% of the noradrenaline-labelled intercepting nerves were enlarged preterminal bundles and only 17% were terminal fibres. These results indicate that the oestrogenized myometrium is unattractive for sympathetic nerves and inhibits organotypic sympathetic reinnervation.

Differential effects of oestrogen on developing and mature uterine sympathetic nerves.

Oestrogen is a key factor in the remodelling of uterine sympathetic nerves during puberty and the oestrous cycle; these nerves are influenced by changes in their target uterine tissue. The magnitude of oestrogen-induced responses might however be influenced by the maturation stage of sympathetic nerve fibres, the age of the neurons and/or the developmental state of the uterus. We have therefore compared the sympathetic innervation of the uterus following chronic oestrogen treatment of infantile/prepubertal and young adult intact and ovariectomised rats. Treatment of infantile/prepubertal rats resulted in the complete loss of intrauterine noradrenaline (NA)-labelled sympathetic nerves and a marked reduction in the total NA content in the uterine horn. Chronic treatment of young adult rats had little effect. To examine whether the age of the neurons or the degree of development of the uterus determined responsiveness of nerves to oestrogen, we assessed the effects of oestrogen on the sympathetic reinnervation of intraocular transplants of young adult uterine myometrium into ovariectomised adult host rats. Early treatment (10 days post-transplantation) resulted in less sympathetic innervation than late treatment (30 days post-transplantation). Measurements of nerve growth factor (NGF) levels in the uterine horn of control rats before and after puberty and following infantile/prepubertal chronic oestrogen treatment and acute oestrogen treatment of young adult rats revealed a coordinated increase between the growth of the uterus and NGF protein levels. Thus, developing and recently regrown sympathetic nerves are more susceptible to oestrogen-induced changes in the uterus than mature nerves, differential susceptibility is not related to the age of the neurons or the developmental state of the uterus and changes in NGF protein do not account for the differential susceptibility of developing and mature uterine sympathetic nerve fibres to oestrogen. Growing sympathetic fibres are more vulnerable to oestrogen than mature fibres and nerve fibres that have been in contact for longer periods with their target become less susceptible to oestrogen.