Testosterone regulates bone response to inflammation.

This study evaluated the alveolar bone response to testosterone and the impact of Resolvin D2 (RvD2) on testosterone-induced osteoblast function. For the in vivo characterization, 60 male adult rats were used. Treatments established sub-physiologic (L), normal (N), or supra-physiologic (H) concentrations of testosterone. Forty rats were subjected to orchiectomy; 20 rats received periodical testosterone injections while 20 rats received testicular sham-operation. Four weeks after the surgeries, 10 rats in each group received a subgingival ligature around the lower first molars to induce experimental periodontal inflammation and bone loss. In parallel, osteoblasts were differentiated from neonatal mice calvariae and treated with various doses of testosterone for 48 h. Cell lysates and conditioned media were used for the determination of alkaline phosphatase, osteocalcin, RANKL, and osteoprotegerin. Micro-computed tomography linear analysis demonstrated that bone loss was significantly increased for both L and H groups compared to animals with normal levels of testosterone. Gingival IL-1ß expression was increased in the L group (p<0.05). Ten nM testosterone significantly decreased osteocalcin, RANKL, and OPG levels in osteoblasts; 100 nM significantly increased the RANKL:OPG ratio. RvD2 partially reversed the impact of 10 nM testosterone on osteocalcin, RANKL, and OPG. These findings suggest that both L and H testosterone levels increase inflammatory bone loss in male rats. While low testosterone predominantly increases the inflammatory response, high testosterone promotes a higher osteoblast-derived RANKL:OPG ratio. The proresolving mediator RvD2 ameliorates testosterone-derived downregulation of osteocalcin, RANKL, and OPG in primary murine osteoblasts suggesting a direct role of inflammation in osteoblast function.

Antiplatelet drugs reduce the immunoinflammatory response in a rat model of periodontal disease.

BACKGROUND AND OBJECTIVE: After activation, platelets express mediators that modulate inflammation. We hypothesized that drug-induced platelet inactivation may interfere in the inflammatory process in experimental periodontal disease by suppressing the release of biological mediators to the injury site. MATERIAL AND METHODS: To evaluate the effects of antiplatelet drugs on experimental periodontal disease, 60 rats were randomly assigned to six groups (n = 10) and ligatures were placed around lower first molars in three groups. The other three groups were not subjected to the induction of periodontal disease and were used as negative controls. During the experimental period, animals were given aspirin (30 mg/kg) or clopidogrel (75 mg/kg) intragastrically once daily for 3 d. On day 3, they were killed and gingival tissue were used to evaluate myeloperoxidase activity and the expression of the chemokine CXCL4. Hemi-mandibles were used for microscopic evaluation. RESULTS: Clopidogrel significantly reduced the inflammatory infiltrate and increased the amount of collagen fibers. Histometric analysis showed that clopidogrel impaired alveolar bone loss. Expression of CXCL4 was significantly increased (p < 0.001) in rats subjected to periodontal disease. Systemic administration of aspirin and clopidogrel induced a significant decrease ( p < 0.05) in the expression of CXCL4. Treatment with antiplatelet drugs resulted in a significant reduction of myeloperoxidase activity when compared to saline-treated animals with periodontal disease. CONCLUSION: Clopidogrel but not aspirin showed the ability of preventing bone loss in experimental periodontitis.

Potent anti-inflammatory effects of systemically administered curcumin modulate periodontal disease in vivo.

BACKGROUND AND OBJECTIVE: Curcumin is a plant-derived dietary spice with various biological activities, including anticarcinogenic and anti-inflammatory effects. Its therapeutic applications have been studied in a variety of conditions, including rheumatoid arthritis, colon cancer and depression, but no studies have evaluated the effects of curcumin on periodontal disease in vivo. MATERIAL AND METHODS: Experimental periodontal disease was induced in rats by placing cotton ligatures around both lower first molars. Curcumin was given to the rats by the intragastric route daily at two dosages (30 and 100 mg/kg) for 15 d. Control animals received ligatures but only the corn oil vehicle by gavage, and no treatment-negative control animals were included. Bone resorption was assessed by micro-computed tomography, and the inflammatory status was evaluated by stereometric analysis. Both RT-qPCR and ELISA were used to determine the expression of interleukin-6, tumor necrosis factor-α and prostaglandin E(2) synthase in the gingival tissues. Modulation of p38 MAPK and nuclear factor-κB activation were assessed by western blotting. RESULTS: Bone resorption was effectively induced in the experimental period, but it was not affected by either dose of curcumin. Curcumin effectively inhibited cytokine gene expression at both the mRNA and the protein level and produced a dose-dependent inhibition of the activation of nuclear factor-κB in the gingival tissues. Activation of p38 MAPK was not inhibited by curcumin. Curcumin-treated animals also presented a marked reduction of the inflammatory cell infiltrate and increased collagen content and fibroblastic cell numbers. CONCLUSION: Curcumin did not prevent alveolar bone resorption, but its potent anti-inflammatory effect suggests that it may have a therapeutic potential in periodontal diseases.

Electric impedance spectroscopy feature extraction for tissue classification with electrode embedded surgical needles through a modified forward stepwise method.

There has been a growing interest in developing electric impedance sensing surgical tools for tissue identification during surgery. A key facet of this development is identifying distinct features that can be used to identify tissues from one another. This paper explores several feature extraction techniques and classification methods applied to electric impedance data. Furthermore, a modified forward stepwise method is proposed. The method introduces a scoring metric to help select features to add to the model, that is based off of the coefficient of variation and overlapping index from the feature's probability density functions for each of the classes. The proposed and existing methods were applied to spectral data measured at 23 frequencies, from 132 samples across 6 different tissues including ex-vivo bovine kidney, liver and muscle, poultry liver, as well as freshly excised canine testicle and ovary samples. These methods were able to successfully find impedance spectra features for the investigated biological tissues. The best predictive accuracy was with Boruta feature extraction and a Random Forest classifier but without significantly reducing the number of features in the classifier model. The proposed method was able to reduce the number of features in the model to an average of 5.8 features for all tested classifiers. These methods may have use in finding features to discriminate other tissue types, possibly to aid in targeting lesions in minimally invasive cancer treatment surgeries.

Intermittent therapy with 1,25 vitamin D and calcitonin prevents cyclosporin-induced alveolar bone loss in rats.

Bone loss associated with cyclosporin A (CsA) therapy can result in serious morbidity to patients. Intermittent administration of 1,25 Vitamin D and calcitonin reduces osteopenia in a murine model of postmenopausal osteoporosis. The purpose of this study was to evaluate the effects of this therapeutic approach on CsA-induced alveolar bone loss in rats. Forty male Wistar rats were allocated to four experimental groups according to the treatment received during 8 weeks: (1) CsA (10 mg/kg/day, s.c.); (2) 1,25 Vitamin D (2 microg/kg, p.o.; in weeks 1, 3, 5, and 7) plus calcitonin (2 microg/kg, i.p.; in weeks 2, 4, 6, and 8); (3) CsA concurrently with intermittent 1,25 Vitamin D and calcitonin administration; and (4) the control treatment group (vehicle). At the end of the 8-week treatment period, serum concentrations of bone-specific alkaline phosphatase, tartrate-resistant acid phosphatase (TRAP-5b), osteocalcin, interleukin (IL)-1 beta, IL-6, and tumor necrosis factor alpha (TNF-alpha) were measured and an analysis of bone volume, bone surface, number of osteoblasts, and osteoclasts was performed. CsA administration resulted in significant alveolar bone resorption, as assessed by a lower bone volume and an increased number of osteoclasts, and increased serum bone-specific alkaline phosphatase, TRAP-5b, IL-1 beta, IL-6, and TNF-alpha concentrations. The intermittent administration of calcitriol and calcitonin prevented the CsA-induced osteopenic changes and the increased serum concentrations of TRAP-5b and inflammatory cytokines. Intermittent calcitriol/calcitonin therapy prevents CsA-induced alveolar bone loss in rats and normalizes the production of associated inflammatory mediators.

RAP1-RAC1 Signaling Has an Important Role in Adhesion and Migration in HNSCC.

Cell-cell adhesion is a key mechanism to control tissue integrity and migration. In head and neck squamous cell carcinoma (HNSCC), cell migration facilitates distant metastases and is correlated with poor prognosis. RAP1, a ras-like protein, has an important role in the progression of HNSCC. RAC1 is an integrin-linked, ras-like protein that promotes cell migration. Here we show that loss of cell-cell adhesion is correlated with inactivation of RAP1 confirmed by 2 different biochemical approaches. RAP1 activation is required for cell-matrix adhesion confirmed by adhesion to fibronectin-coated plates with cells that have biochemically activated RAP1. This effect is reversed when RAP1 is inactivated. In addition, RAP1GTP-mediated adhesion is only facilitated through α5ß1 integrin complex and is not a function of either α5 or ß1 integrin alone. Moreover, the inside-out signaling of RAP1 activation is coordinated with RAC1 activation. These findings show that RAP1 has a prominent role in cell-matrix adhesion via extracellular matrix molecule fibronectin-induced α5ß1 integrin and supports a critical role for the RAP1/RAC1 signaling axis in HNSCC cell migration.

Simvastatin therapy in cyclosporine A-induced alveolar bone loss in rats.

BACKGROUND AND OBJECTIVE: Cyclosporine A treatment is important in the therapy of a number of medical conditions; however, alveolar bone loss is an important negative side-effect of this drug. As such, we evaluated whether concomitant administration of simvastatin would minimize cyclosporine A-associated alveolar bone loss in rats subjected, or not, to experimental periodontal disease. MATERIAL AND METHODS: Groups of 10 rats each were treated with cyclosporine A (10 mg/kg/day), simvastatin (20 mg/kg/day), cyclosporine A and simvastatin concurrently (cyclosporine A/simvastatin) or vehicle for 30 days. Four other groups of 10 rats each received a cotton ligature around the lower first molar and were treated similarly with cyclosporine A, simvastatin, cyclosporine A/simvastatin or vehicle. Calcium (Ca(2+)), phosphorus and alkaline phosphatase levels were evaluated in serum. Expression levels of interleukin-1beta, prostaglandin E(2) and inducible nitric oxide synthase were evaluated in the gingivomucosal tissues. Bone volume and numbers of osteoblasts and osteoclasts were also analyzed. RESULTS: Treatment with cyclosporine A in rats, with or without ligature, was associated with bone loss, represented by a lower bone volume and an increase in the number of osteoclasts. Treatment with cyclosporine A was associated with bone resorption, whereas simvastatin treatment improved cyclosporine A-associated alveolar bone loss in all parameters studied. In addition, simvastatin, in the presence of inflammation, can act as an anti-inflammatory agent. CONCLUSION: This study shows that simvastatin therapy leads to a reversal of the cyclosporine A-induced bone loss, which may be mediated by downregulation of interleukin-1beta and prostaglandin E(2) production.

A dominant function of p38 mitogen-activated protein kinase signaling in receptor activator of nuclear factor-kappaB ligand expression and osteoclastogenesis induction by Aggregatibacter actinomycetemcomitans and Escherichia coli lipopolysaccharide.

BACKGROUND AND OBJECTIVE: Lipopolysaccharide from gram-negative bacteria is one of the microbial-associated molecular patterns that initiate the immune/inflammatory response, leading to the tissue destruction observed in periodontitis. The aim of this study was to evaluate the role of the p38 mitogen-activated protein kinase (MAPK) signaling pathway in lipopolysaccharide-induced receptor activator of nuclear factor-kappaB ligand (RANKL) expression by murine periodontal ligament cells. MATERIAL AND METHODS: Expression of RANKL and osteoprotegerin mRNA was studied by reverse transcription-polymerase chain reaction upon stimulation with lipopolysaccharide from Escherichia coli and Aggregatibacter actinomycetemcomitans. The biochemical inhibitor SB203580 was used to evaluate the contribution of the p38 MAPK signaling pathway to lipopolysaccharide-induced RANKL and osteoprotegerin expression. Stable cell lines expressing dominant-negative forms of MAPK kinase (MKK)-3 and MKK6 were generated to confirm the role of the p38 MAPK pathway. An osteoclastogenesis assay using a coculture model of the murine monocytic cell line RAW 264.7 was used to determine if osteoclast differentiation induced by lipopolysaccharide-stimulated periodontal ligament was correlated with RANKL expression. RESULTS: Inhibiting p38 MAPK prior to lipopolysaccharide stimulation resulted in a significant decrease of RANKL mRNA expression. Osteoprotegerin mRNA expression was not affected by lipopolysaccharide or p38 MAPK. Lipopolysaccharide-stimulated periodontal ligament cells increased osteoclast differentiation, an effect that was completely blocked by osteoprotegerin and significantly decreased by inhibition of MKK3 and MKK6, upstream activators of p38 MAPK. Conditioned medium from murine periodontal ligament cultures did not increase osteoclast differentiation, indicating that periodontal ligament cells produced membrane-bound RANKL. CONCLUSION: Lipopolysaccharide resulted in a significant increase of RANKL in periodontal ligament cells. The p38 MAPK pathway is required for lipopolysaccharide-induced membrane-bound RANKL expression in these cells.

A novel finding that Streptomyces clavuligerus can produce the antibiotic clavulanic acid using olive oil as a sole carbon source.

AIMS: This study aims to establish whether commercially available food oils can be used by Streptomyces clavuligerus as sole carbon sources for growth and clavulanic acid production. METHODS AND RESULTS: Batch cultures in bioreactors showed that Strep. clavuligerus growth and clavulanic acid yields in a P-limited medium containing 0.6% (v/v) olive oil were respectively 2.5- and 2.6-fold higher than in a glycerol-containing medium used as control. Glycerol- and olive oil-grown cells present different macromolecular composition, particularly lipid and protein content. CONCLUSIONS: Streptomyces clavuligerus uses olive oil as the sole carbon and energy source for growth and clavulanic acid production. Yields and production rates in olive oil are comparable to those reported for oil-containing complex media. Differences in yields and in the macromolecular composition indicate that different metabolic pathways convert substrate into product. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of oils being used as the sole carbon source by Strep. clavuligerus. Apart from economic benefits, interesting questions are raised about Strep. clavuligerus physiology. Defined culture media allow physiological studies to be performed in the absence of interference by other compounds. Understanding how Strep. clavuligerus catabolises oils may have an economic impact in clavulanic acid production.

Protective effects of Tacrolimus, a calcineurin inhibitor, in experimental periodontitis in rats.

OBJECTIVE: Periodontitis is a well-appreciated example of leukocyte-mediated bone loss and inflammation with pathogenic features similar to those observed in other inflammatory diseases, such as arthritis. Since Tacrolimus, is an immunomodulatory drug used for the treatment of some cases of arthritis, we hypothesized that it may modulate periodontal disease. DESIGN: Using a murine model of ligature-induced periodontal disease, we assessed the effects of daily administrations of Tacrolimus (1mg/kg body weight) on bone loss, enzymatic (myeloperoxidase) analysis, differential white blood cells counts, airpouch exudate and cytokine expression for 5-30 days. RESULTS: Radiographic, enzymatic (myeloperoxidase) and histological analysis revealed that Tacrolimus reduced the severity of periodontitis. More specifically, Tacrolimus suppressed the expression of serum interleukin (IL-1beta), tumour necrosis factor (TNF-alpha), IL-6, airpouch exudate PGE(2) and leukocytosis usually observed after the induction of periodontitis. Tacrolimus treatment in periodontitis-induced rats conferred protection against the inflammation-induced tissue and bone loss associated with periodontitis, through a mechanism involving IL-1beta, TNF-alpha and IL-6. CONCLUSIONS: The effects of Tacrolimus on periodontal disease pathogenesis may provide clues to a novel approach to host modulation therapy in destructive periodontal disease.

Effect of Aging on Periodontal Inflammation, Microbial Colonization, and Disease Susceptibility.

Periodontitis is a chronic inflammatory disease induced by a biofilm that forms on the tooth surface. Increased periodontal disease is associated with aging. We investigated the effect of aging on challenge by oral pathogens, examining the host response, colonization, and osteoclast numbers in aged versus young mice. We also compared the results with mice with lineage-specific deletion of the transcription factor FOXO1, which reduces dendritic cell (DC) function. Periodontitis was induced by oral inoculation of Porphyromonas gingivalis and Fusobacterium nucleatum in young (4 to 5 mo) and aged (14 to 15 mo) mice. Aged mice as well as mice with reduced DC function had decreased numbers of DCs in lymph nodes, indicative of a diminished host response. In vitro studies suggest that reduced DC numbers in lymph nodes of aged mice may involve the effect of advanced glycation end products on DC migration. Surprisingly, aged mice but not mice with genetically altered DC function had greater production of antibody to P. gingivalis, greater IL-12 expression, and more plasma cells in lymph nodes following oral inoculation as compared with young mice. The greater adaptive immune response in aged versus young mice was linked to enhanced levels of P. gingivalis and reduced bacterial diversity. Thus, reduced bacterial diversity in aged mice may contribute to increased P. gingivalis colonization following inoculation and increased periodontal disease susceptibility, reflected by higher TNF levels and osteoclast numbers in the periodontium of aged versus young mice.

Segregation of the Anodic Microbial Communities in a Microbial Fuel Cell Cascade.

Metabolic interactions within microbial communities are essential for the efficient degradation of complex organic compounds, and underpin natural phenomena driven by microorganisms, such as the recycling of carbon-, nitrogen-, and sulfur-containing molecules. These metabolic interactions ultimately determine the function, activity and stability of the community, and therefore their understanding would be essential to steer processes where microbial communities are involved. This is exploited in the design of microbial fuel cells (MFCs), bioelectrochemical devices that convert the chemical energy present in substrates into electrical energy through the metabolic activity of microorganisms, either single species or communities. In this work, we analyzed the evolution of the microbial community structure in a cascade of MFCs inoculated with an anaerobic microbial community and continuously fed with a complex medium. The analysis of the composition of the anodic communities revealed the establishment of different communities in the anodes of the hydraulically connected MFCs, with a decrease in the abundance of fermentative taxa and a concurrent increase in respiratory taxa along the cascade. The analysis of the metabolites in the anodic suspension showed a metabolic shift between the first and last MFC, confirming the segregation of the anodic communities. Those results suggest a metabolic interaction mechanism between the predominant fermentative bacteria at the first stages of the cascade and the anaerobic respiratory electrogenic population in the latter stages, which is reflected in the observed increase in power output. We show that our experimental system represents an ideal platform for optimization of processes where the degradation of complex substrates is involved, as well as a potential tool for the study of metabolic interactions in complex microbial communities.

Clopidogrel Enhances Mesenchymal Stem Cell Proliferation Following Periodontitis.

Bone formation is dependent on the differentiation of osteoblasts from mesenchymal stem cells (MSCs). In addition to serving as progenitors, MSCs reduce inflammation and produce factors that stimulate tissue formation. Upon injury, MSCs migrate to the periodontium, where they contribute to regeneration. We examined the effect of clopidogrel and aspirin on MSCs following induction of periodontitis in rats by placement of ligatures. We showed that after the removal of ligatures, which induces resolution of periodontal inflammation, clopidogrel had a significant effect on reducing the inflammatory infiltrate. It also increased the number of osteoblasts and MSCs. Mechanistically, the latter was linked to increased proliferation of MSCs in vivo and in vitro. When given prior to inducing periodontitis, clopidogrel had little effect on MSC or osteoblasts numbers. Applying aspirin before or after induction of periodontitis did not have a significant effect on the parameters measured. These results suggest that clopidogrel may have a positive effect on MSCs in conditions where a reparative process has been initiated.

Bacterial cellulose-hydroxyapatite composites with osteogenic growth peptide (OGP) or pentapeptide OGP on bone regeneration in critical-size calvarial defect model.

This study aimed to evaluate the potential of bacterial cellulose-hydroxyapatite (BC-HA) composites associated with osteogenic growth peptide (OGP) or pentapeptide OGP(10-14) in bone regeneration in critical-size calvarial defects in mice. In this study, the BC-HA, BC-HA-OGP, and BC-HA-OGP(10-14) membranes were analyzed at 3, 7, 15, 30, 60, and 90 days. In each period, the specimens were evaluated by micro-computed tomography (µCT), descriptive histology, gene expression of bone biomarkers by qPCR and VEGFR-2 (vascular endothelial growth factor) quantification by ELISA. Three days post-operative, Runx2, Tnfrsf11b and Bglap bone biomarkers were upregulated mainly by BC-HA OGP and BC-HA OGP(10-14) membranes, suggesting an acceleration of the osteoblast differentiation/activity with the use of these biomaterials. At 60 and 90 days, a high percentage of bone formation was observed by µCT for BC-HA and BC-HA OGP(10-14) membranes. High expression of some bone biomarkers, such as Alpl, Spp1, and Tnfrsf11b, was also observed for the same membranes on days 60 and 90. In conclusion, the BC-HA membrane promoted a better bone formation in critical-size mice calvarial defects. Nevertheless, incorporation of the peptides at the concentration of 10(-9) mol L(-1) did not improve bone regeneration potential in the long-term.

Evaluation of anionic collagen membranes in the treatment of class II furcation lesions: an histometric analysis in dogs.

This study aims to evaluate the effect of using anionic collagen membranes in guided tissue regeneration treatment of Class II furcation lesions in dogs. The defects were created in the buccal furcation of 16 mandibular premolars of four dogs. After 56 days without plaque control, the sites were scaled and divided into two groups according to the treatment applied: control sites, open flap debridement; and test sites, guided tissue regeneration treatment. The animals were killed after 3 months. Histological and histometrical analyses showed that the collagen membrane was better than open flap debridement in terms of newly formed cementum and epithelial migration prevention. It provided effective blockade of epithelial tissue and promoted regeneration of lost periodontal tissues, suggesting that the membrane warrants further study.

Bacillus thuringiensis growth and toxicity. Basic and applied considerations.

Despite the known importance of the composition of culture media and culture conditions on Bacillus thuringiensis growth and toxicity, very few reviews are concerned with this subject. This article reviews some aspects of the microbiology of Bacillus thuringiensis, and how toxicity is affected by the composition of growth media and bioreactor operation.

Regeneration of Class III furcation defects with basic fibroblast growth factor (b-FGF) associated with GTR. A descriptive and histometric study in dogs.

BACKGROUND: The poor predictability of periodontal regenerative treatment of Class III furcation defects stimulates the study of alternatives to improve its results, such as the use of polypeptide growth factors. The objective of this study was to evaluate, both histologically and histometrically, the effects of topical application of basic fibroblast growth factor (b-FGF) associated with guided tissue regeneration (GTR) in the treatment of Class III defects surgically induced in dogs. METHODS: All second and fourth premolars of 5 mongrel dogs were used and randomly assigned to one of three treatment groups: group 1 (control), treated with scaling and root planing, tetracycline hydrochloride (125 mg/ml) conditioning, and GTR with a collagen membrane; group 2, same treatment as group 1 plus 0.5 mg of b-FGF; group 3, same treatment as group 1 plus 1.0 mg of b-FGF. After a 90-day healing period, routine histologic processing and staining with hematoxylin and eosin and Masson trichrome were performed. RESULTS: The descriptive analysis indicated better regenerative results in both groups treated with b-FGF while the histometric data, analyzed by means of analysis of variance (ANOVA), showed greater filling of the defects in group 2 in comparison to the defects in groups 3 and 1, respectively, which was represented by a smaller area of plaque-occupied space (P = 0.004) as well as a greater amount of newly formed cementum (P = 0.002). CONCLUSIONS: These results indicate that b-FGF, especially in smaller doses, may enhance the regenerative results in Class III furcation lesions, leading to greater filling of these defects with both mineralized and non-mineralized tissues.

Treatment of gingival recession: comparative study between subepithelial connective tissue graft and guided tissue regeneration.

BACKGROUND: Various procedures have been proposed to treat gingival recession, but few studies compare these procedures to each other. The purpose of this study was to evaluate a clinical comparison of subepithelial connective tissue graft (SCTG) and guided tissue regeneration (GTR) with a collagen membrane in the treatment of gingival recessions in humans. METHODS: Twenty-four defects were treated in 12 patients who presented canine or pre-molar Miller Class I and/or II bilateral gingival recessions. Both treatments were performed in all patients, and clinical measurements were obtained at baseline and 18 months after surgery. These clinical measurements included gingival recession height (GR), root coverage (RC), probing depth (PD), keratinized tissue width (KT), and final esthetic result. RESULTS: Both SCTG and GTR with a bioabsorbable membrane and bone graft demonstrated significant clinical and esthetic improvement for gingival recession coverage. The SCTG group was statistically significantly better than GTR for height of GR (SCTG = 0.2 mm, GTR = 1.12 mm, P= 0.02) and KT (SCTG = 4.58 mm, GTR = 2.5 mm, P<0.0001). However, PD was statistically significantly better for GTR than SCTG treatment (GTR = 1.66 mm, SCTG = 1.00, P= 0.01). The 2 procedures were statistically similar in root coverage (SCTG = 95.6%, GTR = 84.2%, P= 0.073). The esthetic condition after both treatments was satisfactory (P= 0.024). CONCLUSIONS: It was concluded that the gingival recessions treated with the SCTG group were superior for GR, RC, and KT clinical parameters, while GTR demonstrated better PD reduction. The final esthetic results were similar using both techniques.

Efecto de la persistencia bacteriana sobre la eficacia de la enrofloxacina y ciprofloxacina frente a una cepa de Escherichia coli

En este trabajo se evaluó el efecto de las bacterias persistentes presentes en un inóculo de alta densidad de una cepa autóctona de Escherichia coli sobre la eficacia de enrofloxacina y ciprofloxacina mediante ensayos in vitro de curvas de muerte bacteriana y de determinación de la concentración preventiva de mutantes. En las curvas de muerte realizadas sobre inóculos de alta densidad, ningún antibiótico presentó actividad bactericida y solo permitieron la sobrevida de bacterias persistentes. En el ensayo para determinar la concentración preventiva de mutantes, sobre la superficie del agar de las placas con elevadas concentraciones de enrofloxacina y ciprofloxacina, las bacterias persistentes permanecieron viables sin desarrollar colonias y adoptando morfología filamentosa como una forma de adaptación y supervivencia. Se discute la utilidad clínica de las concentraciones preventivas de mutantes de enrofloxacina y ciprofloxacina sobre E. coli ya que, estas elevadas concentraciones permitirían la sobrevida de una sub-población de bacterias persistentes originando un reservorio biológico que podría dar origen a infecciones crónicas y a favorecer la emergencia de mutantes resistentes.

This work evaluated the effect of persister cells present in a high inocula size of a wild strain of Escherichia coli on the efficacy of enrofloxacin and ciprofloxacin by in vitro time-kill curve assays and mutant prevention concentration testing. In time-kill curves performed with high inocula size, no antibiotics showed bactericidal activity, but only allowed the survival of persister cells. In the assay to determine the mutant prevention concentration, on the surface of agar plates containing high enrofloxacin and ciprofloxacin concentrations, persister cells remained viable and without bacterial colonies development and adopting filamentous morphology as a form of adaptation and survival. The clinical usefulness of mutant prevention concentrations of enrofloxacin and ciproflocxacin against Escherichia coli is discussed, as these high concentrations would allow the survival of a sub-population of persister cells originating a biological reservoir that could give rise to chronic infections and favor the emergence of resistant mutants.

LPS induces greater bone and PDL loss in SPARC-null mice.

Individuals with periodontal disease have increased risk of tooth loss, particularly in cases with associated loss of alveolar bone and periodontal ligament (PDL). Current treatments do not predictably regenerate damaged PDL. Collagen I is the primary component of bone and PDL extracellular matrix. SPARC/Osteonectin (SP/ON) is implicated in the regulation of collagen content in healthy PDL. In this study, periodontal disease was induced by injections of lipopolysaccharide (LPS) from Aggregatibacter actinomycetemcomitans in wild-type (WT) and SP/ON-null C57/Bl6 mice. A 20-µg quantity of LPS was injected between the first and second molars 3 times a week for 4 weeks, whereas PBS control was injected into the contralateral maxilla. LPS injection resulted in a significant decrease in bone volume fraction in both genotypes; however, significantly greater bone loss was detected in SP/ON-null maxilla. SP/ON-null PDL exhibited more extensive degradation of connective tissue in the gingival tissues. Although total cell numbers in the PDL of SP/ON-null were not different from those in WT, the inflammatory infiltrate was reduced in SP/ON-null PDL. Histology of collagen fibers revealed marked reductions in collagen volume fraction and in thick collagen volume fraction in the PDL of SP/ON-null mice. SP/ON protects collagen content in PDL and in alveolar bone in experimental periodontal disease.