Ultrahistochemical analysis of glycosaminoglycan hydrolysis in the rat periodontal ligament. II. Aryl sulfatase and bone resorption

Analysis of arylsulfatases A and B, acid phosphatase, lactate dehydrogenase, and aspartate transaminase in chronic periapical lesions of endodontic origin

Attempts were made to detect and measure the activities of arylsulfatases. A&B acid phosphatase, lactate dehydrogenase, and glutamate oxaloacetate transaminase (aspartate transaminase) enzymes in human chronic lesions of endodontic origin. Thirteen periapical lesions of endodontic origin and 11 noninflamed control periapical tissues were obtained. The specimens were carried to the laboratory on liquid nitrogen and kept at -70 degrees C. Samples were thawed, homogenized, and then assayed for enzyme activities. The specific activities of arylsulfatase A (nmol/hr/mg protein) were 55.0+/-10.7 (chronic lesions) vs. 3.4+/-2.2 (controls) (p < 0.01). Arylsulfatase B specific activities (nmol/hr/mg protein) were 50.3+/-6.4 (chronic lesions) vs 91.8+/-18.4 (controls). Total acid phosphatase activities (mU/mg protein) were 45.8+/-6.6 (chronic lesions) vs. 26.8+/-3.1 (controls). Lactate dehydrogenase activities (Berger-Broida units/mg protein) of the chronic periapical lesions were significantly higher than the control group (362+/-63.2) vs. (140+/-46.0) (p < 0.05). There was no significant difference between the specific activities of aspartate transaminase in chronic lesions and the control group (68.0+/-14.5) vs. (53.0+/-10.4) mU/mg protein).

Time and position-specific expression of glycosaminoglycans in rat molar cementum related to physiological tooth movement

The role of glycosaminoglycans (GAGs) and proteoglycans during cementogenesis is not known. In this study, we have analysed the temporal and spacial expression of GAGs in the cellular cementum of 10-30 weeks old rats, immunohistochemically using monoclonal antibodies 2B6 and 3B3, specific for chondroitin 4-sulfate/dermatan sulfate and chondroitin 6-sulfate, respectively. Both 2B6- and 3B3-epitopes were expressed at similar position and time in the rat cellular cementum. Two types of cellular cementum were identified; GAG-positive and GAG-negative cementum. The former corresponded to the lightly stained and the latter to the darkly stained cementum in sections stained with haematoxylin and eosin. The GAG-positive cementum was seen at the distal side of dentine surface and appeared most thick at, middle of the apical half roots, whereas the other parts of the cementum were the GAG-negative. Distribution of GAG-positive cementum showed changes with age of animals. In 10-15 week old rats, the GAG-positive cementum occupied most of the cementum layer, covering a thin layer of the GAG-negative cementum. The cellular cementum of 20-30 week old rats consisted of three layers; GAG-negative, GAG-positive and GAG-negative cementum from dentine to cementum surface, reducing the GAG-positive area. Because our previous study has demonstrated that the lightly stained cementum is uncalcified, the present result suggests a correlation between calcification and contents of GAGs in the cellular cementum. Further, time- and position-specific expression of GAGs indicates their relation to the physiological tooth movement, which has been known in the rat molars.

Physiological studies of turkey tibial dyschondroplasia

Comparative differences between tibial dyschondroplastic (TD) and age-matched control turkey epiphyseal cartilages were studied using cellular, metabolic, and extracellular matrix characteristics. Alkaline phosphatase and aryl sulfatase activities were measured as variables of calcification and cartilage degradation, respectively. There was a decrease in the activities of both enzymes in TD tissues. An increase in tissue phosphate concentrations was noted in the TD tissue whereas neither tissue calcium nor serum calcium and phosphorous concentrations were affected. Profiles of noncollagenous and collagenous proteins from normal and TD-affected tissues were compared following in vitro biotinylation of epiphyseal cartilage followed by a sequential extraction using 4 M guanidine HCl and pepsin digestion, respectively. Electrophoretically separated proteins from both extracts were analyzed on Western blots and compared for any prominent differences between normal and TD cartilages. Biotinylation enhanced the detectability of extracted proteins. There were, however, no major differences in the patterns of noncollagenous or collagenous proteins between the two groups of tissues. Tibial dyschondroplastic lesions further exhibited a large number of dead chondrocytes, which increased with severity of lesion. There appears to be no significant difference in the pattern of extracellular-matrix-associated proteins. However, enzyme and metabolic activities of TD-affected cartilages were significantly reduced, and this may be due to premature death of chondrocytes in the process of development.

Biochemical and histochemical analysis of the enzyme arylsulfatase in human lesions of endodontic origin

Lesions of endodontic origin are areas of inflammatory response which occur as a result of untreated disease process within the root canal system. Lysosomal hydrolytic arylsulfatase A and B have been identified as major enzymes initiating and propagating bone loss by degrading chondroitin-4-sulfate. The purpose of this investigation was to examine human lesions of endodontic origin for the presence of arylsulfatase A and B. Fifteen periapical lesions were obtained at the time of periapical surgery. The lesions were analyzed for the presence of arylsulfatases using the spectrophotometer by monitoring the liberated 4-nitrocatechol at 515-nm wavelength. The same lesions were examined histochemically using the electron microscope. Five control samples from healthy periodontal ligament were evaluated in a similar manner. The results showed higher levels of arylsulfatase A in lesions than in control tissues, and marked activity of arylsulfatase B in lesions, whereas no activity of this enzyme was detected in the control specimen. Histochemically, all lesions showed positive staining for enzyme activity, whereas the controls were negative. These findings indicate that arylsulfatase A and B play a role in the pathogenesis of human lesions of endodontic origin.

Characteristic localization of carbohydrates in osteoclasts by lectin cytochemistry

Lectin cytochemistry was performed to clarify the process of glycosylation and the localization of glycocalyx in osteoclasts. Microslicer sections of decalcified rat tibiae were incubated in the presence of HRP-conjugated lectins (Con A, PNA, MPA, WGA, UEA-1). Lectin reactions in cell organelles revealed that glucose (Glc) and mannose (Man) are transferred to carbohydrate chains in nuclear envelopes, rough endoplasmic reticuli, and the cis and medial sides of the Golgi apparatus. N-acetylgalactosamine (GalNAc), N-acetylglucosamine (GlcNAc), and/or N-acetylneuraminic acic (NANA) residues are transferred, in turn, in the Golgi apparatus. Lectin reactions detected in lysosomal structures suggest that some sugar residues are incorporated into carbohydrate chains of hydrolytic enzymes, such as acid phosphatase and arylsulfatase. Others would be transported to plasma membranes as glycocalyx. PNA and MPA reactions were most evident on ruffled borders of osteoclasts. On the other hand, cement-line-like structures on bone surfaces displayed Con A, MPA, and WGA positive reactions. The following factors suggest that osteoclasts actively metabolize sugar: characteristic localization of glycocalyx in osteoclasts reflect the polarity of osteoclasts, and carbohydrate complexes in cement-line-like structures seem to play an important role in the coupling phenomenon in bone tissue.

Impact of streptozotocin-induced diabetes on rat blood and alveolar bone affected by occlusal stress

Adult male and female rats were used as test animals. The experimental diabetes mellitus was provoked with one dose of i.v. injection of streptozotocin (65 mg/kg body weight), which interferes with the insulin release mechanism in pancreatic beta cells. After a follow-up period of 10 wk an average loss of 10% of body weight and an increase of 25% in the amount of blood obtained by decapitation was recorded in the test animals. The biochemical assays performed on the serum of the diabetic rats showed, for both sexes, a fourfold rise in the plasma glucose level, a threefold rise in plasma alkaline phosphatase activity and plasma alanine transferase activity as well as a 1.5-fold rise in plasma creatine value. The two latter values indicated systematic disorders reflected in the liver and the kidneys. An increase in serum total calcium and hydroxyproline values was also detected. The clinical studies of the gingiva showed diminished tissue resistance in diabetic rats. The histologic studies of alveolar bone revealed retarded formation of bone matrix and new bone in diabetic animals. However, the stimulated metabolism in alveolar bone, due to the artificially induced stress, increased marginal bone cell activity in both the diabetic and the control group, resulting in increased crestal resorption in the former group. The differences in tissue response observed among the diabetic animals affected and unaffected by stress originated from the disturbed recovering mechanism typically found in diabetic animals.

Bone cell biology: the regulation of development, structure, and function in the skeleton

Bone cells compose a population of cells of heterogeneous origin but restricted function with respect to matrix formation, mineralization, and resorption. The local, mesenchymal origin of the cells which form the skeleton contrasts with their extraskeletal, hemopoietic relatives under which bone resorption takes place. However, the functions of these two diverse populations are remarkably related and interdependent. Bone cell regulation, presently in its infancy, is a complicated cascade involving a plethora of local and systemic factors, including some components of the skeletal matrices and other organ systems. Thus, any understanding of bone cell regulation is a key ingredient in understanding not only the development, maintenance, and repair of the skeleton but also the prevention and treatment of skeletal disorders.

Osteoclast abnormalities in idiopathic osteopetrosis. Reference to the ultrastructural histochemistry study

In order to investigate skeletal abnormalities in a case of idiopathic osteopetrosis, a bone biopsy was taken from the anterior iliac crest and prepared for ultrastructural and histochemical study. There was a drastic reduction in osteoclastic bone resorption. The ruffle border and sealing zone, which are the osteoclast cell surface markers of bone resorption, were absent. The cells were highly vacuolated, and the vacuoles contained large amounts of a residual organic material which reacted strongly with acid phosphatase. Acid phosphatase activity was never found outside the cell, and in particular, not at the bone-cell interface. This suggests that the defect in bone resorption is caused by cell membrane abnormalities and the lack of ruffle border formation, rather than the inability of the lysosomal enzymes to digest the bone matrix.

Arylsulphatase activity in human gingival crevicular fluid

Arylsulphatase activity in fluid collected from non-inflamed (n = 5), gingivitis (n = 5) and periodontitis (n = 5) subjects was assayed. The mean volume activity for each group was: non-inflamed = 768 +/- 165 nm/ml per h; gingivitis = 2431 +/- 1118 nm/ml per h; periodontitis = 2860 +/- 1839 nm/ml per h. The mean total unit activity for each group was: non-inflamed = 0.326 +/- 0.076 nm; gingivitis = 1.394 +/- 0.411 nm; and periodontitis = 3.571 +/- 1.700 nm. Analysis of fluid from isolated sites in periodontitis suggests that reporting total unit activity (absolute amount of enzyme activity) is more meaningful than reporting volume activity (enzyme concentration) for arylsulphatase activity.

Cellular enzyme activity associated with tissue degradation following orthodontic tooth movement in man

Enzyme histochemical techniques were used as markers of macrophage activity and differentiation in the periodontal tissues following orthodontic tooth movement in man. The enzymes studied included lactate dehydrogenase, glucose-6-phosphate dehydrogenase, succinic dehydrogenase, acid phosphatase and its tartrate resistant isoenzyme, arylsulfatase, aminopeptidase M and prostaglandin synthetase. Chloroacetyl esterase activity was studied in order to detect possible neutrophilic degrading activity. Intense activities of arylsulfatase and prostaglandin synthetase and a moderate activity of aminopeptidase M were found in cells degrading the hyaline zone. However, no activity of tartrate resistant acid phosphatase was found in these cells. Giant cells in contact with bone surfaces adjacent to the hyaline zone exhibited an intense activity of succinic dehydrogenase, tartrate resistant acid phosphatase and aminopeptidase M. Chloroacetyl esterase activity did not change following orthodontic treatment. The results indicate that macrophages in various stages of differentiation were responsible for the degradation of the hyaline zone and alveolar bone during orthodontic tooth movement. The enzymatic differences were probably due to the influence of the immediate cellular environment. Prostaglandin synthetase activity, which may be interpreted as a sign of prostaglandin secretion, was associated with the degradation of the hyaline zone in man.

The origin of osteoclasts: evidence, clinical implications and investigative challenges of an extra-skeletal source

Recent evidence for an extraskeletal origin of osteoclasts and the historical record of the genesis of osteoclasts are examined critically. Reviews of the structure, function and development of osteoclasts from mononuclear precursors, the local regulation of bone resorption and the coupling of bone formation to preceding resorption are presented as a background for discussing the clinical implications for management of osteolytic bone diseases. The roles of osteoclasts and macrophages as phagocytes are compared and contrasted, and recent evidence for macrophage heterogeneity resulting from site-specific monoblastic precursors is reviewed. The implications of these recent developments in macrophage biology are extrapolated to osteoclasts and the existence of site-specific, extraskeletal osteoclast precursors is proposed. Finally, the investigative challenges inherent in these perspectives are discussed.

Stimulation of aryl sulfatase in rat peritoneal macrophages exposed to bone in vitro

Rat peritoneal macrophages elicited by injection of thioglycollate were cultured in the absence and presence of non-vital, milled rat bone or latex beads. After 0, 48, 96, and 144 hours exposure to these substances, the levels of aryl sulfatase B were determined. Cells exposed to bone demonstrated a significant (p less than .001) time-dependent increase in the specific activity of aryl sulfatase B. After 144 hours the specific activity of aryl sulfatase in cells exposed to bone was 20 fold higher than that in the 144 hour controls. There were no significant differences in the levels of aryl sulfatase B in controls over time, nor were the levels of enzyme in those exposed to latex beads difference from controls. We conclude that the specific activity of aryl sulfatase B increases when macrophages resorb bone and suggest that this enzyme could be used as a marker or index for bone resportion.

Dynamic histomorphometry of alveolar bone remodeling in the adult rat

Alveolar bone normally undergoes remodeling on one side of the socket and modeling on the opposite side as the tooth migrates at a rate of 6.7 micrometer per day. Periodontal ligament width, however, remains constant. Because of this very high turnover rate, this bone is a good model to study bone modeling and remodeling activities. This study was undertaken in order to measure the different cellular events occurring during tooth migration along the alveolar bone of the rat. The histomorphometric measurements performed on this model permitted us to calculate the duration of each phase of the remodeling cycle, i.e., resorption lasts about 1.5 days and reversal about 3.5 days. Since the duration of the forming phase is about 1 day (Guyomard and Baron, '74), the total duration of each remodeling cycle is about 6 days. This time is very short compared to 60--120 days in adult human trabecular bone. Additionally, in this model each osteoclast resorbs 2--4 times its own volume of bone per day. Based on this knowledge, it will be possible to measure accurately the effects of experimental conditions on bone cells and bone remodeling in this rat alveolar bone model.