The Ciliopathy Protein CC2D2A Associates with NINL and Functions in RAB8-MICAL3-Regulated Vesicle Trafficking.

Ciliopathies are a group of human disorders caused by dysfunction of primary cilia, ubiquitous microtubule-based organelles involved in transduction of extra-cellular signals to the cell. This function requires the concentration of receptors and channels in the ciliary membrane, which is achieved by complex trafficking mechanisms, in part controlled by the small GTPase RAB8, and by sorting at the transition zone located at the entrance of the ciliary compartment. Mutations in the transition zone gene CC2D2A cause the related Joubert and Meckel syndromes, two typical ciliopathies characterized by central nervous system malformations, and result in loss of ciliary localization of multiple proteins in various models.

NINL and DZANK1 Co-function in Vesicle Transport and Are Essential for Photoreceptor Development in Zebrafish.

Ciliopathies are Mendelian disorders caused by dysfunction of cilia, ubiquitous organelles involved in fluid propulsion (motile cilia) or signal transduction (primary cilia). Retinal dystrophy is a common phenotypic characteristic of ciliopathies since photoreceptor outer segments are specialized primary cilia. These ciliary structures heavily rely on intracellular minus-end directed transport of cargo, mediated at least in part by the cytoplasmic dynein 1 motor complex, for their formation, maintenance and function.

Neurofilament localization and phosphorylation in the developing inner ear of the rat.

Detailed understanding of neurofilament protein distribution in the inner ear can shed light on regulatory mechanisms involved in neuronal development of this tissue. We assessed the spatio-temporal changes in the distribution of neurofilaments in the developing rat inner ear between embryonic day 12 and 30 days after birth, using antibodies against phosphorylated as well as non-phosphorylated light (NFL), medium (NFM) and heavy (NFH) neurofilament subunits. Our results show that during development, the onset of neurofilament expression in the rat inner ear is on embryonic day 12, earlier than previously shown.

Development of a non-invasive murine infection model for acute otitis media.

Otitis media (OM) is one of the most frequent diseases in childhood, and Streptococcus pneumoniae is among the main causative bacterial agents. Since current experimental models used to study the bacterial pathogenesis of OM have several limitations, such as the invasiveness of the experimental procedures, we developed a non-invasive murine OM model. In our model, adapted from a previously developed rat OM model, a pressure cabin is used in which a 40 kPa pressure increase is applied to translocate pneumococci from the nasopharyngeal cavity into both mouse middle ears.

Detection of bacteria in healthy middle ears during cochlear implantation.

Objective: To assess whether free-living and/or biofilm bacteria are present in the putative sterile middle ear cavity before insertion of the electrode array during cochlear implantation.

Design: Prospective study.

Setting: Tertiary academic hospital.

Advances in understanding the pathogenesis of pneumococcal otitis media.

In this review, a state of the art on otitis media research is provided with emphasis on the role of Streptococcus pneumoniae in the pathogenesis of this disease. Articles have been selected by MEDLINE search supplemented with a manual crosscheck of bibliographies. Pathogenic mechanisms in middle ear and eustachian tube are described.

Involvement of glycosaminoglycans in the attachment of pneumococci to nasopharyngeal epithelial cells.

Streptococcus pneumoniae is a major bacterial pathogen involved in the development of otitis media. The pathogenic mechanisms of this middle ear disease, including the bacterial adherence mechanisms to the mucosal epithelial cells of the host, are poorly understood. In this study, the role of glycosaminoglycans in the adhesion of pneumococci to mucosal epithelial cells is examined.

Genetic relatedness between pneumococcal populations originating from the nasopharynx, adenoid, and tympanic cavity of children with otitis media.

Previous studies have shown that Streptococcus pneumoniae exists in both middle ear effusions and the upper respiratory region from children with otitis media with effusion (OME), but it remains unclear whether these strains represent genetically identical clones. Therefore, it cannot be determined whether these bacteria originate from a common source. To determine the presence of pneumococci at different anatomical locations of OME patients, conventional culture and PCR techniques were used.

Bacterial otitis media: a new non-invasive rat model.

This study describes the development of a physiological rat model for otitis media. The model is based on the assumption that bacteria, intranasally introduced into the nasopharynx, will be transferred into the middle ear cavity during swallowing provided that the ambient air pressure is higher than the middle ear pressure. This model demonstrates that small pressure changes, generated in a pressure cabin under controlled conditions, can be used as driving force for the transfer of bacteria into the middle ear cavity resulting in bilateral otitis media.

Changes in ultrastructural characteristics of endolymphatic sac ribosome-rich cells of the rat during development.

It has recently been demonstrated that endolymphatic sac (ES) ribosome-rich (dark) cells respond to induced endolymph changes and are thus likely to be involved in endolymph homeostasis. Therefore, we studied the ultrastructural characteristics of rat ES ribosome-rich cells during development in order to determine the cellular distribution of organelles involved in protein metabolism, secretion and absorption, indicative for their contribution to endolymph homeostasis. During embryonal stages ribosome-rich cells contain a limited number and variety of organelles and are predominantly involved in the production of components for cell growth and differentiation.

Antigenic as well as nonantigenic stimuli induce similar middle ear responses in the rat.

Objectives/hypothesis: The observation that during otitis media many different types of micro-organisms have been cultured from effusions indicate that, once present in the middle ear cavity, most types of micro-organisms are able to trigger an inflammatory reaction leading to otitis media. The present study was designed to determine the middle ear response after injection of different substances into the middle ear cavity.

Study Design: To determine whether and to what extent an inflammatory response of the middle ear depends on the entering agent, the response in the tympanic cavity was studied by otomicroscopy and histological examination after inoculation of various substances.

Effect of exogenous surfactant on ventilatory and clearance function of the rat's eustachian tube.

Hypothesis And Background: The Eustachian tube has three important functions with respect to the middle ear: ventilation, clearance, and protection. Surfactants are assumed to be important to maintain these functions. The administration of exogenous surfactant may therefore be effective to improve the function of the Eustachian tube.

Differences in endolymphatic sac mitochondria-rich cells indicate specific functions.

Objective/hypothesis: The purpose of the study was to examine the specific involvement of endolymphatic sac mitochondria-rich cells in endolymph homeostasis.

Study Design: Transmission electron microscopy and immunohistochemistry were performed on the endolymphatic sac of young adult rats, and two important developmental stages were also investigated.

Methods: Ultrastructural characteristics of endolymphatic sac mitochondria-rich cells were studied more concisely and compared with renal mitochondria-rich cells (i.

A comprehensive model for the aetiology of otitis media with effusion.

Otitis media with effusion is highly prevalent among young children. Adverse effects of this disorder are mainly restricted to the group of children with a history of recurrent or persistent otitis media with effusion. Early identification, assessment and intervention might prevent these adverse effects.

Developmental aspects of the rat endolymphatic sac and functional implications.

The purpose of this study was to determine specific characteristics of endolymphatic sac (ES) cells of the developing rat that are considered to be involved in endolymph homeostasis. Because intermediate filament proteins (IFPs) are regarded as markers of cell differentiation and basal lamina proteins (BLPs) are essential in cell<=>matrix interactions, we determined the presence of IFPs [cytokeratins (CKs) and vimentin] and BLPs [collagen IV, heparan sulphate proteoglycan (HSPG) and laminin] at different developmental stages before and after birth. In addition, we studied the expression of two enzymes of oxidative metabolism: cytochrome oxidase and succinate dehydrogenase.

Middle ear effusions and structure of the tympanic membrane.

Objective: To study the effect of various middle ear effusions on the structure of the lamina propria of the tympanic membrane.

Methods: Sterile and infective middle ear effusions were induced by obstruction of the eustachian tube in specific pathogen-free (SPF) rats and in rats with upper airway infections (URI), respectively. The condition of the tympanic membrane was monitored at regular intervals.

Semen analysis in the Usher syndrome type 2A.

Semen analysis in patients with Usher syndrome suggested that defective connecting cilia axonemes may be involved in the irreversible, progressive loss of photoreceptors in Usher's syndrome. In the framework of clinical genetic research into Usher syndrome, a pilot study was set up to test these findings. The semen of 6 Usher 2A patients was analysed.

Nature of the tympanic membrane insertion into the tympanic bone of the rat.

The nature of the insertion of the tympanic membrane into the tympanic bone was studied in the rat during the developmental period ranging from 18 days post conception (dpc) to 40 days after birth (dab). Techniques applied were light microscopy, electron microscopy and immunohistochemistry with antibodies to cytoskeletal proteins: vimentin, desmin and alpha-smooth muscle actin (sma) as fibroblast differentiation markers. It was established that the cartilaginous annulus of the pars tensa was connected to the tympanic bone by an interface of specialised connective tissue.

Development of the tubotympanum in the rat.

Objective: To investigate the relationship between the anatomical maturation of the middle ear and that of the eustachian tube and paratubal muscles in the rat.

Design: Wistar rats ranging from gestational day 12 to postnatal day 40 were used.

Methods: Tissue specimens were examined with routine light microscopy and electron microscopy.

Keratinocyte differentiation in acquired cholesteatoma and perforated tympanic membranes.

Objective: To evaluate the type of differentiation of keratinocytes of acquired cholesteatoma and its significance for cholesteatoma invasiveness.

Design: Forty acquired cholesteatomas and 10 tympanic membranes with persisting perforations were snap frozen and processed for immunohistochemical studies. Cytokeratin antibodies that represented all subgroups and antibodies that were directed against collagen components of the basal lamina were applied.

Epidermal differentiation in the human external auditory meatus.

The differentiation of epidermis in the various parts of the human ear canal was documented on the basis of cytokeratin (Ck) expression patterns. Immunohistochemistry was performed on cryostat sections of normal meatal skin using a comprehensive panel of monospecific Ck antibodies representing the main lines of epithelial differentiation. The epidermis of the cartilaginous part showed a Ck profile characteristic of normal skin type differentiation.

Distribution and features of melanocytes during inner ear development in pigmented and albino rats.

In this developmental study, the distribution and features of melanocytes in the inner ear of pigmented and albino rats was investigated with the use of an antibody, which specifically reacts with a melanocyte differentiation antigen present in the membranes of (pre)melanosomes. Melanocyte precursors could be traced from 13 days post conception onwards and the course was followed to their targets in the inner ear. Melanocytes which settle in the modiolus appeared to reach their target along another pathway than strial and vestibular melanocytes.

Growth and differentiation of meatal skin grafts in the middle ear of the rat.

Objective: To determine the behavior of epidermal cells after transplantation in the middle ear.

Design: In a rat model, full-thickness meatal skin grafts were transplanted into the middle ear and studied morphologically and immunohistochemically with the use of antibodies directed against different cytokeratin (Ck) polypeptides, which are markers of different types of epithelial cell differentiation.

Results: The grafts had either transformed into epithelial cysts or had become integrated into the middle ear epithelium.

Developmentally-regulated coexpression of vimentin and cytokeratins in the rat inner ear.

In the present study the expression of vimentin-type intermediate filament proteins and cytokeratins was studied immunohistochemically in the rat inner ear from 12 days postconception up to 40 days after birth. With the use of a broad spectrum monoclonal antibody, cytokeratin expression was found to be present in the whole epithelial lining except for the sensory cells, throughout all the developmental stages examined. Vimentin was detected in the mesenchymal cells, the mesenchyme-derived tissues and the intermediate cells of the stria vascularis, confirming their origin from melanocyte precursor cells.

Expression of intermediate filament proteins in the mature inner ear of the rat and guinea pig.

The expression of intermediate filament proteins was studied in the mature inner ear of the rat and guinea pig, using a panel of polyclonal and monoclonal antibodies directed against cytokeratins, desmin, neurofilament proteins and glial fibrillary acidic protein (GFAP). The epithelial lining of the endolymphatic space displayed a complex expression pattern of cytokeratin filament proteins, suggesting greater cell diversity than was known sofar from morphological studies. The cytokeratin antibodies when applied to the inner ear tissues revealed the presence of only cytokeratin polypeptides which are typical of simple epithelia (i.