The actin-bundling protein L-plastin: a novel local inflammatory marker associated with periodontitis.

BACKGROUND AND OBJECTIVE: L-plastin, an actin-bundling protein, is exclusively expressed in leukocytes and plays a crucial role in immune-mediated events. Periodontitis is a common infectious inflammatory disease that destroys the tooth-supporting tissues. Recent findings using proteomic technologies have demonstrated that L-plastin is one of the few molecules consistently present in the inflammatory exudate of the gingiva in periodontal disease, but not in health. Therefore, this study aimed to investigate in detail the local and systemic role of this molecule in different forms of periodontitis. MATERIAL AND METHODS: A total of 61 subjects who met the inclusion/exclusion criteria were recruited, including 21 with chronic periodontitis, 20 generalized aggressive periodontitis and 20 nonperiodontitis control subjects. Gingival tissue biopsies, gingival crevicular fluid, as well as serum and saliva, were obtained. Immunohistochemistry and quantitative real-time PCR were employed to evaluate the localization and mRNA expression, respectively, of L-plastin. L-plastin levels in gingival crevicular fluid, saliva and serum were measured using ELISA. Statistical analysis was performed using nonparametric methods. RESULTS: Subjects with chronic periodontitis and generalized aggressive periodontitis exhibited significantly higher tissue L-plastin gene expression and gingival crevicular fluid levels than did subjects in the control group but there was no significant difference between the two forms of periodontitis. Within gingival tissue, L-plastin was confined to the inflammatory infiltrate. There was no statistically significant difference between serum and salivary L-plastin levels among the three study groups. CONCLUSION: The elevated gingival tissue expression and gingival crevicular fluid levels of L-plastin in both forms of periodontitis may denote the localized involvement of this novel molecule in the pathogenesis of the disease.

Human root caries: microbiota of a limited number of root caries lesions.

The microbiota of root caries lesions of different grades of severity were studied. Fourteen lesions were examined. The experimental design of the study allowed correlation of histopathologically distinguishable stages with specific and distinct microbial populations. Dentin samples were ground in a sterile mortar and cultured anaerobically on nonselective Columbia blood agar plates supplemented with 5% hemolyzed human blood and on media selective for Lactobacillus spp. and streptococci. The cultivable microbiota were quantitatively speciated using Rapid ID 32A, Rapid ID 32 Strep, API 20 Strep, APIZYM, and API50 CH tests and SDS-PAG electrophoresis. In initial as well as in advanced lesions gram-positive bacteria accounted for approximately 90% of the CFUt. The proportion of Actinomyces, and in particular A. naeslundii was significantly higher (p < 0.05) in initial lesions than in advanced lesions. In contrast, the percentage of Streptococcus and especially S. mutans was higher (p < 0.05) in advanced than in initial lesions. Surprisingly low (0.8% of the CFUt) was the percentage of lactobacilli in advanced lesions. Gram-negative bacteria formed a minor part of the microbiota in both initial and advanced lesions. Among the gram-negative isolates, Prevotella, Selenomonas, and Bacteroides spp. were most noticeable. In advanced lesions, only the outermost layer of 0.5 mm thickness was populated by a high number of bacteria; the following segments harbored a negligible number of bacteria only. It is concluded that root caries is a continuous destruction process which is restricted to a subsurface zone of limited depth. The necrotic dentin is successively worn away, leading to a saucer-shaped cavitation which is repopulated by plaque. The creation of cavitations favors an aciduric flora. This might explain the succession of bacterial populations observed during the destruction process.

Human root caries: microbiota in plaque covering sound, carious and arrested carious root surfaces.

The plaque microbiota covering sound or carious root surfaces were studied and compared with that covering arrested root caries lesions. From each of these categories five extracted teeth were examined. The experimental design of the study allowed us to relate the qualitative and quantitative microbial composition to the degree of integrity of the root surface. Plaque was sampled by a newly developed 'mowing' technique. Plaque samples were cultured anaerobically on nonselective Columbia blood agar plates supplemented with 5% hemolyzed human blood and on media selective for Lactobacillus spp. and streptococci of the mutans group. The cultivable microbiota were quantitatively speciated using Rapid ID 32A, Rapid ID 32 Strep, API 20 Strep, API ZYM, and API 50 CH tests and SDS-PAG electrophoresis. Regardless of the state of mineralization, the microbiota on all surfaces resembled marginal plaque associated with gingivitis. In addition to the gram-positive predominant facultative anaerobic genera Streptococcus, Staphylococcus, Lactobacillus and Actinomyces, gram-negative anaerobes, predominantly Bacteroides, Prevotella, Selenomonas, Fusobacterium, Leptotrichia, and Capnocytophaga, showed the highest isolation frequencies. On all surfaces Actinomyces spp. predominated, with streptococci and lactobacilli forming a minor part of the microbiota. With respect to the detected proportions of anaerobes, microaerophiles, Actinomyces naeslundii, Prevotella buccae and Selenomonas dianae, significant differences were observed between the three categories of root surfaces. The total CFU's on both caries-free and caries-active surfaces were significantly higher than on arrested lesions. In general, the results support a polymicrobial etiology for caries initiation on root surfaces, with A. naeslundii, Capnocytophaga spp., and Prevotella spp. making specific contributions to the processes of cementum and dentin breakdown.

Storage and release of secretory granules in human prolactinomas: modification by bromocriptine.

Electron microscopic morphometric evaluation of the effects of bromocriptine on human prolactinomas during and after short-term parenteral (7 days) and long-term peroral (4-6 weeks) treatment showed that a reduction in size of prolactinoma cells occurs within a few days (half-time to maximum shrinkage, 2.2 days). The number of secretory granules discharged into the intercellular space increased after short-term treatment by a factor of three but the total volume of stored secretory granules did not change significantly. The total volume of cellular lysosomes, both primary and secondary, decreased significantly to about one-half of the pretreatment value. The amount of stored lipoids, end-products of lysosomal activity, decreased in specimens treated for 7 days, but returned to pretreatment levels in specimens treated for 4-6 weeks, suggesting that lysosomal material is discharged from the cells together with the secretory material.

Bromocriptine-induced removal of endoplasmic membranes from prolactinoma cells.

Adenomatous prolactin cells lose 39% of their cytoplasm volume within 7 days after the beginning of bromocriptine treatment. A simultaneous reduction of the rough-surfaced endoplasmic reticulum and the Golgi apparatus occurs. Their membranes are removed by rapid transport along the secretory pathway to the cell surface and to lysosomal destruction.

Perivascular fibrosis in prolactinomas: is it increased by bromocriptine?

Prolonged treatment of patients with pituitary prolactinomas with bromocriptine may increase the consistency of the tumor thereby making selective extirpation more difficult. We made quantitative determinations of the amount of perivascular fibrous tissue in prolactinomas on random electron micrographs, comparing a group of 21 patients treated with bromocriptine for periods longer than 3 months and a control group of 21 patients who did not receive bromocriptine. Statistical analysis of the data showed a significant increase of perivascular fibrous tissue in the treated group (P less than 0.002). We suspect that this fibrosis is a consequence of the rapid shrinkage of prolactinoma cells caused by bromocriptine. Presumably, this cell shrinkage causes enlargement of the extracellular and perivascular spaces which are filled by the deposition of collagen, producing a more dense consistency of the adenoma.

Bromocriptine reduces the size of cells in prolactin-secreting pituitary adenomas.

The morphometric analysis of the size of adenomatous prolactin cells shows that bromocriptine-induced cell shrinkage halts if treatment with the drug is discontinued for more than 2 days. Different cell components (nucleus, cytoplasm, nucleolus) do not react to treatment to the same extent.