Our challenge in oral pathology.

Oral pathology started as a specialty during the 1940s. At that time major problems existed in the diagnosis and treatment of diseases of the oral and facial regions. Today, it is important to be able to distinguish between benign and malignant diseases of the oral and facial regions. The head and neck regions have special embryonic and histogenetic factors that may contribute to diseases not seen elsewhere. This article will discuss the many challenges that face the specialists in oral pathology.

Activation of fibroblast procollagenase by mast cell proteases.

Proteases capable of activating procollagenase from gingiva and from fibroblast and macrophage monolayer cultures were harvested from homogenates of canine tumor mast cells. The mast cell proteases lysed casein and Azocoll but not native collagen. In low salt concentrations the enzymes existed at high molecular weight complexes, which were dissociated by increasing the salt concentration above 1.0 M (NaCl, KCl). Gel filtration in 1.4 M KCl separated the protease activity into three peaks, all of which activated procollagenase. Two of the enzymes showed substrate specificities (hydrolysis of p-tosyl-L-arginine methyl ester and benzoyl-tyrosine ethyl ester) and reactive center reactivities similar to pancreatic trypsin and chymotrypsin. Based on gel filtration, apparent molecular weights of 160 000 (p-tosyl-L-arginine methyl ester esterase), 90 000 (main procollagenase activator) and 36 000 benzoyl-tyrosine ethyl ester esterase) were determined. Activation of procollagenase resulted in a 18-20 000 decrease of the molecular weight. The activation was directly related to the amount of activator added within certain limits. Further addition of activator resulted in proteolytic inactivation of collagenase.

Synthesis and release of procollagenase by cultured fibroblasts.

An inactive collagenase was harvested from both serum-free and serum-supplemented fibroblast monolayer cultures in periods of active collagen synthesis. The latent collagenase did not hydrolyze collagen and did not bind the potent collagenase inhibitor alpha2-macroglobulin. Activation with trypsin imparted to the enzyme the ability to hydrolyze collagen at neutral pH in a typical manner and to form an inhibited complex with alpha2-macroglobulin. The molecular weights, determined by calibrated gel filtration, were 78,000 and 60,000 for the latent and active enzymes, respectively. The data indicate that collagenase is released from the cells in inactive form, as a zymogen.

Procollagenase from bovine gingiva.

1. Collagenase (EC 3.4.24.3) is released from bovine gingival explants in vitro as a zymogen. The zymogen does not hydrolyze collagen and does not form a complex with alpha2-macroglobulin (alpha2-M). It elutes in gel filtration with an apparent molecular weight of approx. 80 000. 2. Incubation of the zymogen with trypsin results in a 15 000-20 000 dalton decrease in molecular weight and imparts to the enzyme the ability to hydrolyze collagen and to form a complex with alppha2-M. 3. The zymogen can be completely separated from the active enzyme to alpha2-M. Likewise, the zymogen can be harvested from cultures supplemented with serum.

Rabbit alveolar macrophage collagenase: evidence of polymeric forms.

Collagenase harvested in vitro from rabbit alveolar macrophages eluted in gel chromatography corresponding to apparent molecular weights of 45 000, 85 000, and 165 000. Reversible changes from one molecular weight to another in low salt concentration and predominance of the 45 000 species in salt concentrations above 1.0 M (NaCl, KCl) suggest that the higher molecular weights represent polymeric forms of collagenase.

Trypsin activation of latent collagenase from several mammalian sources.

Latent collagenase, subject to activation by trypsin, was found in culture fluids of cells and tissues from several mammalian sources. The activation requires exposure to enzymatically active trypsin and cannot be achieved by inhibited or by heat-inactivated trypsin.

Serum inhibition of gingival collagenase.

Collagenases derived from bovine and human gingiva are inhibited effectively by serum. In bovine and human serum fractionated by gel chromatography, alpha2-macroglobulin is the only significant inhibitor of gingival collagenase. alpha11-Antitrypsin inhibited collagenase only in very high concentration and was several hundred-fold less effective than alpha2-macroglobulin. Inhibition of gingival collagenase with alpha2-macroglobulin is accompanied by the formation of an enzyme-inhibitor complex, which has retained no collagenolytic activity.

Bovine gingival collagenase: demonstration and initial characterization.

A collagenase active against native collagen was found in culture fluids of bovine gingiva. The enzyme first appeared in the culture fluid after 1-2 days and could be harvested thereafter for at least 30 days. The collagenase attacked collagen fibrils and cleaved collagen in solution, resulting in reaction products 1/4 and 3/4 of the length of the original molecule. The enzyme was inhibited by serum, by EDTA and by cysteine. The molecular weight was estimated by gel filtration to be 63,000 daltons.

Oxytalan connective tissue fibers: a review.

Oxytalan connective tissue fibers are a separate and distinct fiber type. Although current histochemical methods cannot distinguish pre-elastic from oxytalan fibers, the two fiber types are readily distinguished by electron microscopy. Oxytalan fibers are found in periodontal membranes of all teeth of man, monkeys, rats, guinea pigs and mice. Increased numbers and size of oxytalan fibers are observed in periodontal membranes of teeth subjected to increased stress, such as those used for bridge abutments. Edwards (1968) observed increased size and number of oxytalan fibers in periodontal membranes of dog incisors subjected to orthodontic forces. Some oxytalan fibers serve to support the blood and lymphatic vessels leading to the teeth. Oxytalan fibers appear to have a protein component and a stainable component digestible with beta-glucuronidase after peracetic acid digestion. Oxytalan fibers develop in repair tissues of the periodontal membrane. Although oxytalan fibers probably develop in relation to tumors developed from dental tissues, electron microscopy must be employed to distinguish oxytalan from developing elastic tissues inasmuch as histochemical methods are inadequate.