Human bronchial mucus contains an acid-stable proteinase inhibitor called bronchial mucous inhibitor (BMI) that apparently protects the upper airways from proteolysis by polymorphonuclear leukocyte (PMN) elastase and cathepsin G, and infections of Pseudomonas aeruginosa, which also produces an elastase, can result in considerable lung damage. The possible role of BMI in protecting the lung from proteolytic attack in the presence of P. aeruginosa elastase (a zinc metalloprotease) was investigated. The BMI not only failed to inhibit P. aeruginosa elastase but the ability of BMI to inhibit PMN elastase and cathepsin G was rapidly lost in the presence of the bacterial elastase. The P. aeruginosa elastase also freed active PMN elastase from complexes with BMI, resulting in elastin digestion by both enzymes. The proteolysis of lung tissue observed with P. aeruginosa infections may be caused by a combination of bacterial and PMN proteases. Elastase and cathepsin G released from leukocyte, attracted to P. aeruginosa infection sites, would be free to attack the bronchial tissues after BMI inactivation by P. aeruginosa elastase, adding to the damage caused by the bacterial protease(s).

Based on available knowledge, this study shows that alpha-1-proteinase inhibitor (alpha 1-PI) plays an important role in protecting lung elastin from elastolytic proteinases, particularly human neutrophil elastase (HNE). Studies previous to this one showed that alpha 1-PI was very susceptible to inactivation by oxidants. We sought to use this oxidant sensitivity as an in vivo marker for ozone (O3) and nitrogen dioxide (NO2) exposure. The mechanism of alpha 1-PI inactivation by O3 and NO2 was examined to provide insight concerning the pathogenesis of oxidant-mediated lung damage. Attention also was focused on the bronchial leukocyte proteinase inhibitor (BLPI), which inhibits HNE in the bronchial secretions. Careful examination of blood plasma samples from individuals exposed to 0.5 ppm O3 for four hours on two consecutive days failed to detect any inactivation of alpha 1-PI. This result showed that blood alpha 1-PI was not a satisfactory marker for O3 exposure, but, more importantly, demonstrated that inhaling O3 for short periods does not grossly inactivate this important protein. Studies on BLPI showed that it is a significant inhibitor of HNE and probably plays a more important role in protecting the lung than previously thought. BLPI, like alpha 1-PI, was found to be inactivated by oxidants, including O3 and NO2. The mechanism of O3 inactivation of leukocyte proteinase inhibitors was studied using alpha 1-PI, alpha-1-antichymotrypsin (alpha 1-Achy), BLPI, and Eglin C. While all these inhibitors differed in structure, the concentrations of O3 required for inactivation were essentially the same, except for alpha 1-Achy, which only lost half of its inhibitory activity. It would seem from these results that O3 can damage proteins via the oxidation of any of the following: tryptophan (Trp), methionine (Met), tyrosine (Tyr), or histidine (His) residues. Interestingly, Eglin C, which does not have oxidizable amino acids in its inhibitory active site, was inactivated by the same amount of O3 as BLPI, BLPI was easily inactivated by a methionine-specific oxidant, suggesting an important role for methionine in this inhibitor. In vitro exposure of alpha 1-PI and BLPI to 800 moles of NO2 per mole of inhibitor resulted in 35% and 50% losses of HNE inhibitory activity, respectively. Tryptophan was destroyed by NO2 and studies are in progress to examine effects on other amino acids.

The lysosomal cysteine proteinases cathepsin L and cathepsin B were examined for their effect on the neutrophil elastase inhibitory activity of human α1-proteinase inhibitor (α1PI). Human cathepsin L catalytically inactivated human α1PI by cleavage of the bonds Glu354-Ala355 and Met358-Ser359 (the serine proteinase inhibitory site). Cathepsin B did not inactivate α1PI, even equimolar amounts of enzyme were employed. Cathepsin L is the first human proteinase shown to catalytically inactivate α1PI. These findings, in conjunction with other reports, suggest that α1PI contains a proteolytically sensitive region encompassing residues 350-358. Taken together with the discovery of the elastinolytic activity of cathepsin L, the present findings emphasize the possible importance of cathepsin L in the pathological proteolysis of elastin and diminish the role that can be attributed to cathepsin B in such processes.

No description available.

No description available.

The ureteral vasculature (UV) in 29 male New Zealand rabbits using routine light microscopy, transmission electron microscopy, and scanning electron microscopy of vascular corrosion casts were studied. For corrosion casting the UV was perfused with buffered saline and filled with resin at physiological temperature and pressure. Vascular corrosion casts provide a clear, 3-D view of the microvasculature of the rabbit ureter.

The anatomy and morphometry of venous values associated with the vasculature of the head of the duckling were studied using vascular corrosion casting and scanning electron microscopy. All valves encountered were bicuspid, and casts typically exhibited slight expansions at valve sinuses and deep slits at the sites of valve leaflets. The locations, numbers, and orientations of endothelial nuclei on all surfaces of the valves were clearly revealed by imprints in the casting resin. Endothelial cell densities were significantly higher on the surfaces of valve leaflets (about 10 cells/ 1,000 /μm2) than on other venous surfaces (about 7 cells/ 1,000 μm2). Endothelial nuclei on the medial surface of the valve leaflet were oriented parallel to the long axis of the vessel, whereas those on the lateral surface were oriented perpendicular to that axis. The close proximities of valves in some vessels and the presence of anomalies such as the sharing of leaflets by adjacent valves were readily demonstrated with the corrosion‐casting techniques. These methods provide a useful means for studying the fine, three‐dimensional details of venous valve anatomy.

The origin of different branches of the facial nerve in the rabbit was determined by using retrograde transport of HRP. Either the proximal stump of specific nerves was exposed to HRP after transection, or an injection of the tracer was made into particular muscles innervated by a branch of the facial nerve. A clear somatotopic pattern was observed. Those branches which innervate the rostral facial musculature arise from cells located in the lateral and intermediate portions of the nuclear complex. Orbital musculature is supplied by neurons in the dorsal portion of the complex, with the more rostral orbital muscles receiving input from more laterally located cells while the caudal orbital region receives innervation from more medial regions of the dorsal facial nucleus. The rostral portion of the ear also receives innervation from cells located in the dorsomedial part of the nucleus, but the caudal aspect of the ear is supplied exclusively by cells located in medial regions. The cervical platysma, the platysma of the lower jaw, and the deep muscles (i.e., digastric and stylohyoid) receive input from cells topographically arranged in the middle and ventral portions of the nuclear complex. It is proposed that the topographic relationship between the facial nucleus and branches of the facial nerve reflects the embryological derivation of the facial muscles. Those muscles that develop from the embryonic sphincter colli profundus layer are innervated by lateral and dorsomedial portions of the nuclear complex. The muscles derived from the embryonic platysma layer, including the deep musculature, receive their input from mid to ventral regions of the nuclear complex.

The avian salt gland provides an ideal system for the study of plasma membrane (PM) biogenesis. Feeding ducklings 1% sodium chloride (salt stress) induces the secretory cells of the gland to synthesize large amounts of PM, which forms an extensive basolateral PM domain after 7–9 days of treatment. In the present study, the initial biosynthetic events following salt stress were investigated. In vivo studies using 3H‐uridine indicated that increased rates of RNA synthesis could be detected by 2 hr after the beginning of salt stress and continued through at least 12 hr. Under in vitro conditions, increased rates of protein and glycoprotein synthesis (as monitored by 3H‐leucine and 3H‐fucose incorporation, respectively) were also detected after 2 hr and continued through 7–9 days. Increased levels of Na, K‐ATPase, a specific secretory cell PM marker, were detected after 8 hr of treatment as monitored by specific activity and 3H‐ouabain binding. Sodium dodecyl sulfate‐polyacryl‐amide slab gel electrophoresis coupled with fluorography indicated that both 3H‐leucine and 3H‐fucose were incorporated into partially purified preparations of Na, K‐ATPase isolated after 12 hr. Light microscopic autoradiographic analysis of pulse‐chase experiments indicated that in secretory cells of 12‐hr salt‐stressed glands, 3H‐leucine‐ and 3H‐fucose‐labelled products reached the cell periphery by 1–2 hr after the initial pulse. The incorporation of both tritiated precursors was predominately associated with the secretory cells. Quantitative electron microscopic autoradiography indicated that 3H‐leucine is initially taken up by elements of the rough endoplasmic reticulum (RER) and cytoplasm (5 min postpulse), subsequently transported to and concentrated within components of the Golgi apparatus (10 min of chase), and ultimately incorporated into all domains of the plasma membrane of secretory cells by 1–2 hr of chase. The data is consistent with a flow of newly synthesized membrane components from RER to Golgi to plasma membrane and is analogous to the pattern previously found for the synthesis and processing of PM proteins in a wide variety of cell types.

The microvasculature of the eye of the duckling was studied with microcorrosion casting, scanning electron microscopy, and stereology. Most blood to the eyeball first passes through the arterial ophthalmic rete mirabile, a complex of small arteries which intermixes with a similar complex of veins (venous ophthalmic rete mirabile) at the ventrotemporal angle of the eye. The present study reveals the ultrastructural anatomy and the compact, three‐dimensional arrangement of vessels in this rete, which had been shown by previous investigators to function as a countercurrent heat exchanger. Vessels from this rete include the supraorbital and infraorbital arteries, which supply the eyeball anteriorly, and the ophthalmotemporal artery, which supplies the eyeball posteriorly. The internal ophthalmic and ethmoidal arteries, branches of the cerebral carotid artery, anastomose with the ophthalmotemporal artery posteriorly. Blood is distributed to the eyeball anteriorly by two ring arteries: the iridial ring artery, which circumscribes the iris and which receives blood from the long ciliary and infraorbital arteries; and the more peripheral, ciliary ring artery, which receives blood mostly from the infraorbital and ethmoidal arteries. Within the iris is a dense, freely anastomosing bed of capillaries which extends to the edge of the pupil and then loops back beneath the ciliary body. The vasculature of the ciliary body consists of radially arranged plates of anastomosing capillaries of irregular bore which mimic the contours of that organ, but permit changes in pupil diameter. The present study demonstrates the three‐dimensional anatomy of the very dense capillary net of the choriocapillaris deep to the retina and the capillary mass of the pecten, and thus supports the finding of earlier investigators that nutrients diffusing from these structures nourish the avascular retina. The pecten consists of a pleated sheet of freely anastomosing capillaries which protrudes into the vitreous body from near the optic nerve. The choriocapillaris and the pecten are supplied by branches of the ophthalmotemporal artery: the former by numerous short posterior ciliary arteries, the latter by two or three arteries which further divide into one or two smaller vessels for each of its folds. Veins of the choroid layer at the periphery of the anterior surface of the eyeball, and to some extent on its lateral walls, are revealed by the corrosion‐casting technique as unusual, flattened vessels of large caliber which lie in closely spaced parallel arrays. The large surface area thus created may function in heat dissipation. These veins join with others from the choriocapillaris to form a large dorsal and a large ventral posterior ciliary vein. Blood from the pecten and from the choriocapillaris in the nasal, central, and temporal regions of the posterior surface of the eyeball is drained by the ophthalmotemporal vein. Vascular casts of veins are often distinguishable from those of arteries by bore morphology and by the presence of valves, but also by the shapes of endothelial nuclear depressions left in the plastic. The high resolution obtained with the present technique reveals details of microvasculature and of vessel distribution in the avian eye not previously described. Names for some of these vessels are suggested.