Type II collagen distribution in the ear of the guinea pig fetus.

By using monoclonal antibodies to type II collagen and immunohistochemical techniques, we studied the distribution of type II collagen in the developing guinea pig ear. Type II collagen appearance and disappearance corresponded to cartilage development and resorption. Type II collagen was identified in Meckel's and Reichert's cartilages, the cartilage plate of the auricle and external acoustic meatus, the ossicles, eustachian tube cartilage, and the otic capsule. Type II collagen also appeared with the development of structures in noncartilaginous parts including the tympanic membrane, tympanic annulus, basilar membrane, spiral limbus, spiral ligament, and osseous spiral lamina, Rosenthal's canal, the maculae of the utricle and saccule, and the semicircular canal membrane, crista ampullaris, and endolymphatic duct. Type II collagen is distributed widely in the ear after the early stages of development. Thus, type II collagen should be considered an important structural component of the ear.

Type II collagen distribution in the ear of the developing chick embryo.

The localization of type II collagen was immunohistochemically studied in the developing chick ear using monoclonal antibodies. Type II collagen appeared under the basal lamina of the otocyst from developmental stages 14 to 16. In the otic capsule, endolymphatic duct, and semicircular canal membrane, type II collagen appeared in stage 23 or 24. From stages 28 to 29, type II collagen appeared in the primitive columella, endolymphatic sac, and fibrocartilaginous plate. Type II collagen was first observed in the crista ampullaris, basilar membrane, macula sacculi, and utriculi in stages 30 and 31. Type II collagen was not detected in the endolymphatic sac beyond developmental stage 37 and the amount of type II collagen in the otic capsule and columella decreased after stage 40. The wide distribution of type II collagen in the inner ear throughout the development of the chick embryo suggests that this collagen may act as a basic structural component of the ear.

Type II collagen distribution in rodents.

The anatomical distribution of type II collagen in animal ears was studied by immunohistochemical techniques, using defined monoclonal antibodies to type II collagen. Type II collagen was observed in the cartilage plate of the auricle and external auditory meatus, tympanic annulus, lamina propria of tympanic membrane (pars tensa), interossicular joints, stapes footplate, eustachian tube cartilage, enchondral layer and globuli interossei of the otic capsule, Rosenthal canal, cribriform base, osseous spiral lamina, spiral ligament, limbus, tectorial membrane, semicircular canal membrane and subepithelial layer of the ampullary crista, utricular and saccular maculae, and the endolymphatic duct and proximal part of the sac.

Validity of ear oximetry in clinical exercise testing.

Because of suspicion that the ear oximeter might measure the oxyhemoglobin saturation of arterial blood inaccurately during heavy exercise, we made concurrent ear oximetric and blood measurements on 14 consecutive patients with arterial catheters during clinical exercise tests. After correcting for carboxyhemoglobin, the estimated and measured values for the oxyhemoglobin saturation of the blood agreed well, as did resting ear and blood values; however, during heavy exercise, ear oximetric values were falsely elevated in two patients with interstitial pulmonary disease and were falsely depressed in five patients with cardiovascular limitation to exercise. In another patient, ear oximetric values declined during heavy exercise despite mild hyperoxia, suggesting hypoperfusion of the ear. Considering the clinical and physiologic importance of oxyhemoglobin saturation, ear oximetric values during heavy exercise should be cautiously interpreted.

Immunohistochemical localization of collagens in the ear.

The aim of this work was to prepare specific antibodies to various types of collagen in order to study on immunohistological localization of collagen under normal and pathologic conditions. Human type I and III collagens were extracted from human dura mater and placenta using limited pepsin digestion followed by differential salt precipitation and chromatographic purification. The purity of collagens was assessed by SDS polyacrylamide gel electrophoresis. Antibodies to type I and III were prepared in rabbits, and showed a high reaction with the corresponding human collagens, and these antibodies were tested to determine activity using ELISA. However, antibody to type I also showed some cross-reaction with type III, and antibody to type III, with type I. Using these antibodies, tissue distribution of collagen was examined in the middle ear by peroxidase anti-peroxidase method. In granulation tissue, it was revealed that types I and III co-existed.

Biosynthesis of tropoelastin by elastic cartilage.

Elastic ear cartilage and aortae from nine-day-old hamsters were incubated in Krebs-Ringer medium containing ascorbate, beta-aminopropionitrile and either [14C]proline or [3H]valine. The [14C]proline-labeled proteins were separated by chromatography on Agarose A-5 m in sodium dodecyl sulfate and their [14C]-hydroxyproline content measured. A fraction having an approximate molecular weight of 70,000 measured by polyacrylamide gel electrophoresis had a [14C]hydroxyproline content of 9.1% in the cartilage and 11.8% in the aorta. This fraction was also relatively heavily labeled with [3H]valine. The 70,000 dalton, [3H]valine-labeled protein of both the aorta and ear cartilage was precipitated by elastin-specific antibody prepared against hamster insoluble aorta elastin, but no higher molecular weight protein was immunoprecipitated. Based on these results we identify the 70,000 dalton protein from the elastic cartilage as tropoelastin.

Requirement for vasoactive amines for production of delayed-type hypersensitvity skin reactions.

The skin sites of the mouse where delayed-type hypersensitivity (DTH) reactions are most easily elicited (foot pads and ears) are particularly rich in 5-hydroxytryptamine (5-HT)-containing mast cells. Since mice are deficient in circulating basophils, which play a role in at least some DTH reactions, we investigated the possibility that the mast cells were playing an important role in the evolution of the skin reactions of DTH in mice. We found that reserpine, a drug which depletes mast cells of 5-HT, abolished the ability of the mouse to make DTH reactions in the skin. The suppressive effect of reserpine could be partially blocked by monoamine oxidase inhibitors which prevent the degradation of 5-HT in the cytosol of the mast cell. Spleen cells of immune, reserpine-treated mice transferred DTH reactions to nonimmune mice normally, indicating that the reserpine treatment did not affect immune T cells. DTH reactions could not be transferred into reserpine-treated mice. We suggest that T cells are continually emigrating from the blood, through postcapillary venule endothelium, by a mechanism which does not depend on vasoactive amines. If they are appropriately immune and meet the homologous antigen in the tissue, they induce mast cells to release vasoactive amines which cause postcapillary venule endothelial cells to separate, allowing the egress from the blood of cells which ordinarily do not recirculate. The secondarily arriving vasoactive amine-dependent cells are responsible for the micro- and macroscopic lesions of DTH reactions. Chemotactic factors may also be involved in bringing cells to the DTH reaction sites but we propose that T-cell regulation of vasoactive amine-containing cells allows the effector cells to pass through the endothelial gates after they are called.

Some aspects of wound healing research: a review.

Mammalian response to injury essentially is that of tissue repair and re-epithelialization. The most important component of repair tissue is collagen, and after injury collagen turnover is greatly increased. Collagen biosynthesis is initiated by nuclear DNA of fibroblasts; the steps in biosynthesis are complex but studies of collagen biosynthesis may eventually have clinical potential. Normally, wound healing lasts for up to 2 years but nutritional and metabolic factors, such as malnutrition, delay healing; hyperalimentation would likely be beneficial under these conditions. Other factors that influence wound healing are the oxygen tension in tissues, the hemodynamic status, and the effects of substances such as cortisone, vitamins A and C, and zinc.