Histological evaluation of the pulp in teeth from dogs with naturally occurring periodontal disease.

The purpose of this investigation was to evaluate the pulp of dog teeth affected by advanced periodontal disease. Histological examination was done on demineralized teeth extracted during clinical treatment of mature, client owned small and medium-size breed dogs with either good periodontal health or with advanced naturally occurring periodontal disease. Routinely stained sections from 5 clinically normal teeth and 22 teeth with advanced periodontitis from dogs between 5 and 12-years of age were examined using light microscopy. The pulp cavities of most teeth were narrow with low cellularity and some fibrosis of the pulp. Findings specific to periodontally affected teeth included acute and chronic pulpitis, vascular congestion, and pulp necrosis. A glomus body was identified in the pulp of one tooth and areas of poorly mineralized cementum were seen in both normal and diseased teeth. Age related changes in dog teeth appear similar to those reported for man and the rat. In addition to age related changes, the pulp of dog teeth with advanced periodontal disease were frequently inflamed or necrotic. This may reflect the advanced periodontitis affecting these teeth or a mechanical effect related to excessive tooth mobility. Further study is required to determine the etiology and significance of these findings and to investigate pulp status in less severely diseased teeth.

Early odontoblastic layer response to cavity preparation and acid etching in rats.

The aim of this study was to establish the early odontoblastic layer response and quantitatively to estimate the number of odontoblasts after cavity preparation with and without acid etching. Half of 56 cavities prepared on rats' first upper molars were acid etched. Qualitative and morphometric analyses were made on histological and ultrathin sections 5 min, 6 h, 24 h and 72 h post-operatively. Under the etched cavity, a greater disarrangement of odontoblasts was found, modifications in nuclear shape and condensed chromatin 5 min. post-operatively. An additional reduction of odontoblast number was detected and an increase of aspirated cell number 5 min, 6 h and 24 h post-operatively, pronounced hyperaemia 6, 24 and 72 hours post-operatively and increased odontoblast number 72 hours post-operatively, compared to unetched cavities. In conclusion, injury to the odontoblastic layer was greater, but numerical renewal of the odontoblastic layer began earlier in etched cavities compared to unetched cavities.

Effects of periodontal dressings on fibroblasts and gingival wound healing in dogs.

In the present study the effects of different commercially available periodontal dressings (Peripac, Barricaid, Fittydent, Reso-Pack and Myzotect-tincture) on fibroblast (V-79-379A) proliferation and survival were tested in vitro. Barricaid, Fittydent and Reso-Pack periodontal dressings have only small inhibitory effects on cell proliferation (83.3 +/- 9%, 71.6 +/- 8.7% and 87.3 +/- 4.5% of control after 48 h, respectively) in comparison with the great inhibitory effect of Myzotect-tincture (2.9 +/- 0.1%) and Peripac (33.7 +/- 11.4%) (p < 0.001). Barricaid was the only dressing where 41% of cells survived after exposure, while the other four dressings killed all the cells in 6 days. In addition, the healing of artificially created gingival wounds covered by Barricaid and Reso-Pack was followed for 7 days in 12 Beagle dogs. Histological evaluation of gingival tissue demonstrated that wounds covered by Reso-Pack showed the best epithelisation and vascularity and the least inflammatory reaction in first 4 days. Later the observed parameters were similar with those of wounds covered by Barricaid or without pack. The present results indicate that Peripac periodontal dressing and Myzotect-tincture showed the highest cytotoxicity to fibroblasts in vitro. From the histological observations in Beagle dogs Reso-Pack has been found to be the most suitable dressing, followed by Barricaid.

Astereological analysis of FRTL-5 cells as an effect of thyrotropin and irradiation.

FRTL-5 cell line is a cloned epithelial follicular cell line from Fischer rat thyroids. This cell line expresses many of the thyroid differentiated markers in vitro. Their growth and function depend on thyrotropin (TSH) as the main regulatory hormone. In this astereological analysis, the authors concentrate on FRTL-5 nuclei as the most vulnerable part of the cell. Using morphometrical variables, they wished to discover the morphologically identifiable sign of transformation of FRTL-5 cells after irradiation and to study the effect of different TSH concentrations. FRTL-5 cells were grown in a medium of 4 different concentrations of TSH (0, 0.1, 1, 10 mU/ml) and irradiated with 0 Gy, 2 Gy, and 4 Gy. The results showed that the nuclear-cytoplasmic ratio decreases after irradiation with doses of 4 Gy or if TSH was included in the medium. The nuclear maximum diameter of FRTL-5 cells increased with higher concentrations of TSH more obviously after irradiation with 4 Gy than with 2 Gy. On the basis of astereological analysis, it was concluded that different concentrations of TSH and irradiation exert an effect especially upon FRTL-5 cell nuclei. The possible transformation of FRTL-5 cells after culturing in TSH medium and after irradiation could be confirmed by injection into an animal of the Fischer strain.

In vivo administration of recombinant TNF-alpha promotes bone resorption in mice.

BACKGROUND: In vitro studies demonstrated that proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) modulates bone metabolism. OBJECTIVE: The aim of our study was to confirm the ability of TNF-alpha to induce osteoclastogenesis and bone resorption in an in vivo experiment, with the use of calvarial model in mice. MATERIALS AND METHODS: Twenty C57-Black mice were divided into four groups with five animals in each. The first group was infused subcutaneously on their back with recombinant mouse (rm) TNF-alpha via osmotic minipumps for 3 d, the second group was similarly infused with phosphate-buffered saline (PBS), the third group was infused with rmTNF-alpha to the region above the parietal bone and the fourth group with PBS in the same manner. Number of osteoclasts on parietal bone was determined morphometrically. Serum calcium and phosphates were monitored colorimetrically. RESULTS: Serum calcium level and number of osteoclasts on parietal bone were significantly greater after infusion of rmTNF-alpha above the parietal bone, whereas after subcutaneous delivery these parameters were similar to the control group. CONCLUSION: We are concluding that TNF-alpha has the ability to change the bone metabolism in a paracrine manner only.

Influence of restraint stress on ligature-induced periodontitis in rats.

The influence of stress on periodontal breakdown in Wistar rats was analyzed during experimental periodontitis, induced by placing silk ligatures around the maxillary right second molar teeth. The rats were divided into three groups with 10 animals in each; the first group was exposed to restraint stress for 12 h d(-1) for a period of 4 wk; the second group was exposed to restraint stress for 2.5 h d(-1) for a period of 4 wk; the third group served as a control group. Ligation for 4 wk resulted in an accelerated periodontal degradation, whereas the restraint stress by itself had no significant effect. Combined stress and ligation resulted in a significantly higher attachment loss and alveolar bone resorption than either treatment alone, while no differences were seen between the two stress regimens. After 4 wk, a reduced body weight was found in both restrained groups of rats and a reduced weight of the thymus in the rats restrained for 12 h d(-1), while no changes were observed in the weight or composition of the suprarenal glands. We conclude that stress alone does not result in periodontal disease but may modulate the pathophysiological processes of already present periodontal inflammation, resulting in accelerated degradation of periodontal tissues.

Influence of subcutaneous administration of recombinant TNF-alpha on ligature-induced periodontitis in rats.

Proinflammatory cytokine tumor necrosis factor alpha (TNF-alpha) was found in inflamed periodontal tissues and many studies pointed to its significant role in development of periodontal disease. In this study, the influence of subcutaneously administered recombinant human TNF-alpha (rhTNF-alpha) on inflammatory reaction and periodontal breakdown in rats was analyzed during experimental periodontitis, induced by placing silk ligatures around the maxillary right second molar tooth. The rats were divided into two groups with five animals in each; the first group was infused subcutaneously with rhTNF-alpha via osmotic pumps for 2 weeks and the second group was infused with phosphate-buffered saline (PBS) in the same manner. Inflammatory reaction and periodontal breakdown was evaluated morphometrically on hematoxylin and eosin stained sections. Serum ionized calcium and inorganic phosphates were monitored colorimetrically. Serum calcium and phosphate levels were similar in rats receiving rhTNF-alpha and PBS. Ligation resulted in accelerated periodontal breakdown, while subcutaneous rhTNF-alpha administration by itself had no significant effect. Combined effect of subcutaneous rhTNF-alpha administration and ligation resulted in a significantly greater inflammatory reaction and periodontal breakdown then either treatment alone. We concluded that the subcutaneous administration of rhTNF-alpha accelerates the progression of experimental periodontitis in rats.

Demonstration of apoptosis-associated cleavage products of DNA, complement activation products SC5b-9 and C3d/dg, and immune complexes CIC-C3d, CIC-IgA, and CIC-IgG in the urine of patients with membranous glomerulonephritis.

AIM: To investigate the involvement of complement activation and apoptosis in the pathogenesis of membranous glomerulonephritis by determining the concentrations of apoptosis-associated 180 bp nucleosomes and complement activation products SC5b-9 and C3d/dg in the urine of patients with membranous glomerulonephritis. METHODS: Morning urine was taken from 15 patients with immunohistologically established membranous glomerulonephritis. Apoptosis-associated 180 bp nucleosomes, complement activation products SC5b-9, C3d/dg, and immune complexes CIC-C3d, CIC-IgA, and CIC-IgG were detected in the urine samples by using antigen-specific enzyme-linked immunosorbent assay. RESULTS: Concentrations of measured parameters were expressed in units of standard deviation, ie, relatively to the average concentrations measured in healthy subjects. We found drastically increased concentrations of apoptosis-associated 180 bp nucleosomes (13.71+/-14.97; p=0.047), complement activation products SC5b-9 (197.07+/-134.88; p=0.003) and C3d/dg (38.70+/-43.35; p=0.048), and immune complexes CIC-C3d (11.01+/-13.39; p=0.74), CIC-IgA (7.93+/-4.38; p=0.001), and CIC-IgG (20.56+/-10.87; p=0.001) in the urine of patients with an active form of membranous glomerulonephritis. All studied molecules were absent, or present in very low concentrations, in healthy subjects and patients with membranous glomerulonephritis in remission. The mean differences between healthy controls and patients with the active disease were statistically significant in all parameters, except CIC-C3d. CONCLUSIONS: There is an association of complement activation and apoptosis with membranous glomerulonephritis. Correlation analysis suggests that the excretion of apoptosis-associated 180 bp nucleosomes, SC5b-9, C3d/dg, and immune complexes containing IgA and IgG in the urine of patients with active membranous glomerulonephritis does not depend solely on the passive transport together with other proteins, but is probably an independent active process.