Morphology of intraepithelial corpuscular nerve endings in the nasal respiratory mucosa of the dog.
Corpuscular nerve endings in the nasal respiratory mucosa of the dog were investigated by immunohistochemical staining specific for protein gene product 9.5 by light and electron microscopy. In the nasal respiratory mucosa, complex corpuscular endings, which displayed bulbous, laminar and varicose expansions, were distributed on the dorsal elevated part of the nasal septum and on the dorsal nasal concha. The endings were 300-500 microm long and 100-250 microm wide. Some axons gave rise to a single ending while others branched into 2 endings. Cryostat sections revealed that the corpuscular endings were located within the nasal respiratory epithelium. On electron microscopy, immunoreactive nerve terminals that contained organelles, including mitochondria and neurofilaments, were observed within the epithelial layer near the lumen of the nasal cavity. Some terminals contacted the goblet cell. Such terminal regions were covered by the cytoplasmic process of ciliated cells and were never exposed to the lumen of the nasal cavity. These nerve endings are probably activated by pressure changes. (+info)
Comparative anatomy of the vomeronasal organ complex in bats.
The morphology of the vomeronasal organ complex was histologically described in eight out of fourteen chiropteran species investigated. Of the six families examined, all except the family Pteropodidae (suborder Megachiroptera) were found to have at least one member possessing the organ. The organ is best developed in phyllostomatids. It is absent in vespertilionids (including a Myotis embryo) except in Miniopterus. An accessory olfactory bulb is reported for the first time in the latter. The organ is described for the first time in Rhinopoma, Megaderma, and Hipposideros. The organ in Rhinolophus is also described. Homologous anterior nasal cartilages and patent nasopalatine ducts are present in all species. The organ occupies the anterior ventral nasal septum region. In Megaderma and Hipposideros it is level with the nasal cavity floor. Areas of epithelium similar to olfactory epithelium have been observed in some organs. Epithelia, vascular sinuses, vomeronasal nerves, paravomeronasal ganglia, accessory olfactory bulbs, and vomeronasal glands have been investigated. In bats with regressed or rudimentary organs (Megaderma, Rhinopoma, Rhinolophus, Hipposideros) accessory olfactory bulbs could not be identified. Thus, presence of the organ does not necessarily indicate presence of the accessory olfactory bulb. Septal pockets located superior to the organ complex and lined with pseudostratified columnar epithelium are described in Hipposideros and may play a part in nasophonation. A unique role is proposed for the organ in the feeding behaviour of Desmodus. The desirability of extending the useful terms 'diosmatic' and 'monosmatic' to all vertebrates in reference to their respective possession or lack of the vomeronasal organ is suggested. (+info)
Stromelysin 1, neutrophil collagenase, and collagenase 3 do not play major roles in a model of chondrocyte mediated cartilage breakdown.
AIMS: To determine the collective roles of stromelysin 1, neutrophil collagenase, and collagenase 3 in chondrocyte mediated cartilage proteoglycan and type II collagen degradation in tissue culture model systems. METHODS: Bovine nasal cartilage explants were cultured with and without recombinant human interleukin 1 alpha (IL-1 alpha), recombinant human tumour necrosis factor alpha, or retinoic acid. Proteoglycan and type II collagen release were determined by colorimetric assay and immunoassay, respectively, in the absence and presence of matrixin inhibitors. Potential toxic effects of the inhibitors were assessed by measuring rates of glycolysis. RESULTS: Loss of proteoglycan and type II collagen from nasal cartilage was inhibited by batimastat, a broad spectrum matrixin inhibitor. BB-3437, a selective inhibitor of stromelysin, neutrophil collagenase, and collagenase 3, at the concentrations used in this study, showed a weak but dose dependent inhibitory effect on the IL-1 stimulated degradation of type II collagen, but had virtually no effect on proteoglycan breakdown. Neither inhibitor affected rates of glycolysis. CONCLUSIONS: Stromelysin 1, neutrophil collagenase, and collagenase 3 are unlikely to contribute to chondrocyte mediated proteoglycan degradation in our model system. The modest effect of a selective inhibitor of these enzymes on IL-1 stimulated collagen breakdown suggests a minor role for one or more of these proteinases; potent inhibition by an inhibitor of interstitial collagenase and the gelatinases suggests that these enzymes play a major role in IL-1 stimulated, chondrocyte mediated type II collagen breakdown from nasal cartilage. (+info)
The robust australopithecine face: a morphogenetic perspective.
The robust australopithecines were a side branch of human evolution. They share a number of unique craniodental features that suggest their monophyletic origin. However, virtually all of these traits appear to reflect a singular pattern of nasomaxillary modeling derived from their unusual dental proportions. Therefore, recent cladistic analyses have not resolved the phylogenetic history of these early hominids. Efforts to increase cladistic resolution by defining traits at greater levels of anatomical detail have instead introduced substantial phyletic error. (+info)
Resistance of small leucine-rich repeat proteoglycans to proteolytic degradation during interleukin-1-stimulated cartilage catabolism.
A bovine nasal-cartilage culture system has been utilized to analyse the catabolic events occurring in response to interleukin-1beta over a 14-day period. An early event following the start of interleukin-1 treatment was the release of glycosaminoglycan into the culture medium. This release was accompanied by the appearance in the tissue, and shortly thereafter also in the culture media, of a globular domain (G1)-containing aggrecan degradation product generated by the action of aggrecanase. Link protein was also released from the cartilage with a similar timeframe to that of the G1 fragment, although there was no evidence of its proteolytic degradation. By comparison with aggrecan, the small leucine-rich repeat proteoglycans decorin, biglycan and lumican showed a resistance to both proteolytic cleavage and release throughout the culture period. In contrast, fibromodulin exhibited a marked decrease in size after day 4, presumably due to proteolytic modification, but the major degradation product was retained throughout the culture period. Also in contrast with the early changes in the components of the proteoglycan aggregate, type II collagen did not display signs of extensive degradation until much later in the culture period. Collagen degradation products compatible with collagenase action first appeared in the medium by day 10 and increased thereafter. These data demonstrate that the leucine-rich repeat proteoglycans are resistant to proteolytic action during interleukin-1-stimulated cartilage catabolism, compared with aggrecan. This resistance and continued interaction with the surface of the collagen fibrils may help to stabilize the collagen fibrillar network and protect it from extensive proteolytic attack during the early phases of cartilage degeneration. (+info)
Identification of aggrecanase activity in medium of cartilage culture.
Erosion of cartilage is a major feature of joint diseases, i.e., osteoarthritis and rheumatoid arthritis, which leads with time to a loss of joint function. Proteolytic cleavage of the aggrecan core protein is a key event in the progress of these joint diseases. Aggrecan degradation has been believed to be mediated by a putative proteinase, aggrecanase. We identified aggrecanase activity in conditioned medium from explant culture of bovine nasal cartilage stimulated by retinoic acid. The activity was partially purified more than 10,000-fold. The enzyme cleaves at the aggrecanase site (Glu(373)-Ala(374)) but not at the MMP site (Asn(341)-Phe(342)) in the interglobular domain of the aggrecan. It also cleaves at Glu(1971)-Leu(1972), which is located in the gap region in the chondroitin sulfate attachment region prior to the aggrecanase site. The enzyme is a typical Ca(2+)-dependent metalloproteinase with a unique salt-dependency and is inhibited by several hydroxamate-based inhibitors for matrix metalloproteinases. Heparin and chondroitin sulfate inhibited the enzyme in a dose-dependent manner, suggesting that the large carbohydorate in aggrecan is important for substrate recognition by aggrecanase. (+info)
A new animal model for relapsing polychondritis, induced by cartilage matrix protein (matrilin-1).
Relapsing polychondritis (RP) differs from rheumatoid arthritis (RA) in that primarily cartilage outside diarthrodial joints is affected. The disease usually involves trachea, nose, and outer ears. To investigate whether the tissue distribution of RP may be explained by a specific immune response, we immunized rats with cartilage matrix protein (matrilin-1), a protein predominantly expressed in tracheal cartilage. After 2-3 weeks, some rats developed a severe inspiratory stridor. They had swollen noses and/or epistaxis, but showed neither joint nor outer ear affection. The inflammatory lesions involved chronic active erosions of cartilage. Female rats were more susceptible than males. The disease susceptibility was controlled by both MHC genes (f, l, d, and a haplotypes are high responders, and u, n, and c are resistant) and non-MHC genes (the LEW strain is susceptible; the DA strain is resistant). However, all strains mounted a pronounced IgG response to cartilage matrix protein. The initiation and effector phase of the laryngotracheal involvement causing the clinical symptoms were shown to depend on alphabeta T cells. Taken together, these results represent a novel model for RP: matrilin-1-induced RP. Our findings also suggest that different cartilage proteins are involved in pathogenic models of RP and RA. (+info)
Evidence that the inhibition of cartilage proteoglycan breakdown by mannosamine is not mediated via inhibition of glycosylphosphatidylinositol anchor formation.
The effect of mannosamine, an inhibitor of glycosylphosphatidylinositol (GPI) anchor formation, on chondrocyte-mediated cartilage proteoglycan breakdown was investigated using cartilage explant cultures. Mannosamine inhibited interleukin 1alpha-, tumour necrosis factor alpha- and retinoic acid-stimulated proteoglycan release from bovine nasal and articular cartilage, and retinoic acid-stimulated proteoglycan release from human cartilage. Its effects on two GPI-anchored proteins [the urokinase receptor, which binds urokinase-type plasminogen activator (uPA) to cell surfaces, and alkaline phosphatase] were also studied using bovine chondrocytes. Enzyme histochemistry and zymography demonstrated cell-associated uPA-like serine proteinase activity and PA activity respectively which was not reduced by treatment of chondrocytes with mannosamine at concentrations effective at inhibiting cartilage proteoglycan breakdown. Similarly, the activity of cell-associated alkaline phosphatase was not reduced, except at mannosamine concentrations much higher than those used to inhibit proteoglycan breakdown. These results demonstrate that inhibition of proteoglycan breakdown by mannosamine is too potent to be explained by an effect on GPI-anchor formation. (+info)