The role of DNA damage in the pathogenesis of nitrate tolerance - nitrosative versus oxidative DNA damage

6. Summary Despite the lack of direct evidence from large clinical trials for mutagenic and genotoxic effects of GTN therapy, the present study show s the induction of pre-mutagenic lesions, such as 8- oxo - G and O 6 - me - G by GTN t reatment as well as increased formation of DNA strand breaks. These results were obtained in an in vitro (EA.hy 926 – human endothelial cell line) and in vivo (Wistar rats and C57BL/6 mice) setting. However, GTN - induced DNA damage had no effect on the degr ee of nitrate tolerance but only on other pathological side effects such as oxidative stress, as confirmed by studies in MGMT knockout mice. Of clinical importance , this study establishes potent apoptotic properties of organic nitrates, which has been demo nstrated by the levels of the novel apoptotic marker and caspase - 3 substrate, fractin, as well as levels of cleaved caspase - 3 , the activated form of this pro - apoptotic enzyme . The p rotein analy tical data ha ve been confirmed by an independent assay for the apoptosis , Cell death detection assay (TUNEL) . First, these GTN - mediated apoptotic effects may account for the previously reported anti - cancer effects of GTN therapy (probably based on induction of apoptosis in tumor cells). Second, these GTN - mediated apop totic effects may account for the increased mortality rates observed in the group of organic nitrate - treated patients as reported by two independent meta - analysis (probably due to induction of apoptosis in highly beneficial endothelial progenitor cells as well as in cardiomyocytes during wound healing and cardiac remodeling) . Summary of the current investigations can be seen in Figure 18.

Sciatic neuropathy after body contouring surgery in massive weight loss patients

To date, obesity affects a substantial population in industrialised countries. Due to the increased awareness of obesity-related morbidity, efficient dietary regimens and the recent successes with bariatric surgery, there is now a high demand for body contouring surgery to correct skin abundancies after massive weight loss. The known risks for this type of surgery are mainly wound-healing complications, and, more rarely, thromboembolic or respiratory complications. We present two female patients (23 and 39 years of age) who, in spite of standard positioning and precautions, developed sciatic neuropathy after combined body contouring procedures, including abdominoplasty and inner thigh lift. Complete functional loss of the sciatic nerve was found by clinical and electroneurographic examination on the left side in patient one and bilaterally in patient two. Full nerve conductance recovery was obtained after 6 months in both patients. Although the occurrence of spontaneous neuropathies after heavy weight loss is well documented, this is the first report describing the appearance of such a phenomenon following body contouring surgery. One theoretical explanation may be the compression of the nerve during the semirecumbent positioning combined with hip flexion and abduction, which was required for abdominal closure and simultaneous access to the inner thighs. We advise to avoid this positioning and to include the risk of sciatic neuropathy in the routine preoperative information of patients scheduled for body contouring surgery after heavy weight loss.

Education of tobacco use prevention and cessation for dental professionals--a paradigm shift

The use of tobacco continues to be a substantial risk factor in the development and progression of oral cancer, periodontitis, implant failure and poor wound healing. Dental and dental hygiene education providers have made great advances towards the incorporation of tobacco education into their curricula in recent years. Unfortunately, however, both medical and dental education research has consistently reported schools providing only basic knowledge-based curricula that rarely incorporate more effective, behaviourally-based components affecting long-term change. The limited training of oral healthcare students, at least in part, is reflected in practising dental professionals continuing to report offering incomplete tobacco interventions. In order to prepare the next generation of oral healthcare providers, this paper proposes a paradigm shift in how tobacco use prevention and cessation (TUPAC) may be incorporated into existing curricula. It is suggested that schools should carefully consider: to what level of competency should TUPAC be trained in dental and dental hygiene schools; the importance of establishing rapport through good communication skills; the core knowledge level for TUPAC; suggested instructional and assessment strategies; the importance of continuing professional education for the enhancement of TUPAC.

Endovascular Revascularization of Below-the-Knee Arteries: Prospective Short-Term Angiographic and Clinical Follow-up

PURPOSE: To evaluate arterial lesion characteristics and their impact on angiographic and clinical outcomes after endovascular below-the-knee (BTK) revascularization. MATERIALS AND METHODS: Between April 2008 and June 2009, 33 patients (mean age 74.9 years) with 34 limbs and 50 arterial segments (mean lesion length 59.3 mm) undergoing endovascular BTK revascularization agreed to undergo prospective clinical and intraarterial angiographic 6-month follow-up evaluation. Clinical indication for BTK revascularization was critical limb ischemia (CLI) in 18 patients and delayed wound healing without hemodynamic evidence of CLI and intermittent claudication (IC) in 15 patients. RESULTS: Binary restenosis was observed in 40% of treated segments at 6 months. Primary sustained clinical improvement was 82.4% and 55.9% at 3 months and 6 months. Lesion length was independently associated with binary restenosis (hazard ratio [HR] 1.013, 95% confidence interval [CI] 1.000-1.016, P = .05) and lower rates of primary sustained clinical improvement (HR 1.024, 95% CI 1.006-1.042, P = .008). CONCLUSIONS: Endovascular BTK revascularization yields clinical and angiographic benefits both for patients with IC and for patients with CLI. Although arterial lesion length adversely affects angiographic and clinical outcomes after endovascular revascularization, limb salvage rates were substantially higher compared with the comparatively low patency rates after BTK angioplasty.

Long-term stability of surgical bone regenerative procedures of peri-implantitis lesions in a prospective case-control study over 3 years

Objectives: To evaluate the extent of bone fill over 3 years following the surgical treatment of peri-implantitis with bone grafting with or without a membrane. Material and Methods: In a non-submerged wound-healing mode, 15 subjects with 27 implants were treated with a bone substitute (Algipore®) alone and 17 subjects with 29 implants were treated with the bone substitute and a resorbable membrane (Osseoquest®). Implants with radiographic bone loss ≥1.8 mm following the first year in function and with bleeding and/or pus on probing were included. Following surgery, subjects were given systemic antibiotics (10 days) and rinsed with chlorhexidine. After initial healing, the subjects were enrolled in a strict maintenance programme. Results: Statistical analysis failed to demonstrate changes in bone fill between 1 and 3 years both between and within procedure groups. The mean defect fill at 3 years was 1.3 ± (SD) 1.3 mm if treated with the bone substitute alone and 1.6 ± (SD) 1.2 mm if treated with an adjunct resorbable membrane, (p=0.40). The plaque index decreased from approximately 40–10%, remaining stable during the following 2 years. Conclusion: Defect fill using a bone substitute with or without a membrane technique in the treatment of peri-implantitis can be maintained over 3 years.

The transcriptional regulator megakaryoblastic leukemia-1 mediates serum response factor-independent activation of tenascin-C transcription by mechanical stress

The extracellular matrix protein tenascin-C (TNC) is up-regulated in processes influenced by mechanical stress, such as inflammation, tissue remodeling, wound healing, and tumorigenesis. Cyclic strain-induced TNC expression depends on RhoA-actin signaling, the pathway that regulates transcriptional activity of serum response factor (SRF) by its coactivator megakaryoblastic leukemia-1 (MKL1). Therefore, we tested whether MKL1 controls TNC transcription. We demonstrate that overexpression of MKL1 strongly induces TNC expression in mouse NIH3T3 fibroblasts and normal HC11 and transformed 4T1 mammary epithelial cells. Part of the induction was dependant on SRF and a newly identified atypical CArG box in the TNC promoter. Another part was independent of SRF but required the SAP domain of MKL1. An MKL1 mutant incapable of binding to SRF still strongly induced TNC, while induction of the SRF target c-fos was abolished. Cyclic strain failed to induce TNC in MKL1-deficient but not in SRF-deficient fibroblasts, and strain-induced TNC expression strongly depended on the SAP domain of MKL1. Promoter-reporter and chromatin immunoprecipitation experiments unraveled a SAP-dependent, SRF-independent interaction of MKL1 with the proximal promoter region of TNC, attributing for the first time a functional role to the SAP domain of MKL1 in regulating gene expression.

A phase IIa randomized controlled clinical and histological pilot study evaluating rhGDF-5/?-TCP for periodontal regeneration

The primary objective of this study was to clinically and histologically evaluate periodontal wound healing/regeneration following surgical implantation of recombinant human growth/differentiation factor-5 (rhGDF-5) adsorbed onto a particulate ?-tricalcium phosphate (?-TCP) carrier rhGDF-5/?-TCP into periodontal defects in man.

The adhesion modulating properties of tenascin-w

Tenascins are extracellular matrix glycoproteins associated with cell motility, proliferation and differentiation. Tenascin-C inhibits cell spreading by binding to fibronectin; tenascin-R and tenascin-X also have anti-adhesive properties in vitro. Here we have studied the adhesion modulating properties of the most recently characterized tenascin, tenascin-W. C2C12 cells, a murine myoblast cell line, will form broad lamellipodia with stress fibers and focal adhesion complexes after culture on fibronectin. In contrast, C2C12 cells cultured on tenascin-W fail to spread and form stress fibers or focal adhesion complexes, and instead acquire a multipolar shape with short, actin-tipped pseudopodia. The same stellate morphology is observed when C2C12 cells are cultured on a mixture of fibronectin and tenascin-W, or on fibronectin in the presence of soluble tenascin-W. Tenascin-W combined with fibronectin also inhibits the spreading of mouse embryo fibroblasts when compared with cells cultured on fibronectin alone. The similarity between the adhesion modulating effects of tenascin-W and tenascin-C in vitro led us to study the possibility of tenascin-W compensating for tenascin-C in tenascin-C knockout mice, especially during epidermal wound healing. Dermal fibroblasts harvested from a tenascin-C knockout mouse express tenascin-W, but dermal fibroblasts taken from a wild type mouse do not. However, there is no upregulation of tenascin-W in the dermis of tenascin-C knockout mice, or in the granulation tissue of skin wounds in tenascin-C knockout animals. Similarly, tenascin-X is not upregulated in early wound granulation tissue in the tenascin-C knockout mice. Thus, tenascin-W is able to inhibit cell spreading in vitro and it is upregulated in dermal fibroblasts taken from the tenascin-C knockout mouse, but neither it nor tenascin-X are likely to compensate for missing tenascin-C during wound healing.

Adsorption of Enamel Matrix Proteins to a Bovine Derived Bone Grafting Material and its Regulation of Cell Adhesion, Proliferation and Differentiation

The use of various combinations of enamel matrix derivative (EMD) and grafting materials has been shown to promote periodontal wound healing/regeneration. However, the downstream cellular behavior of periodontal ligament (PDL) cells and osteoblasts has not yet been studied. Furthermore, it is unknown to what extent the bleeding during regenerative surgery may influence the adsorption of exogenous proteins to the surface of bone grafting materials and the subsequent cellular behavior. In the present study, the aim is to test EMD adsorption to the surface of natural bone mineral (NBM) particles in the presence of blood and determine the effect of EMD coating to NBM particles on downstream cellular pathways, such as adhesion, proliferation, and differentiation of primary human osteoblasts and PDL cells.

Effect of sorafenib on murine liver regeneration

Hepatocellular carcinoma (HCC) is a common cause of cancer-related death. Sorafenib prolongs survival of patients with advanced disease and is approved for the systemic treatment of unresectable HCC. It possesses antiangiogenic and antiproliferative properties by way of inhibition of the receptor tyrosine kinases vascular endothelial growth factor receptor 2 (VEGFR-2) and platelet-derived growth factor receptor-beta 1/2 (PDGFR-β) and the kinase RAF. Sorafenib represents a candidate compound for adjuvant therapy in HCC patients. The aim of our study was to investigate whether sorafenib affects liver regeneration. C57BL6 mice received sorafenib orally at 30 mg/kg/day or its vehicle either for 14 days until the day before hepatectomy or starting the day after surgery or both. Animals were sacrificed 24, 72, and 120 hours after hepatectomy. Liver regeneration was calculated as a percent of initial liver weight. Bromodeoxyuridine (BrdU) incorporation and phospho-extracellular signal-regulated kinase (pERK1/2) were determined by immunohistochemistry on liver sections. VEGF-A, PDGF-BB, and hepatocyte growth factor (HGF) levels were measured in liver tissue homogenates. Histological analysis of scar tissue was performed. Treatment stopped 1 day before surgery had no impact on liver regeneration. Continuous sorafenib treatment and treatment started 1 day after surgery had statistically significant effects on liver regeneration at 120 hours compared to vehicle-treated control animals (72% ± 12 versus control 88% ± 15 and 70% ± 13 versus control 86% ± 5 at 120 hours, both P ≤ 0.02). BrdU incorporation showed decreased numbers of positive nuclei in both groups receiving sorafenib after surgery. Phospho-ERK levels were reduced in sorafenib-treated animals. An increase of VEGF-A levels was observed in mice receiving sorafenib. Wound-healing complications were observed in animals receiving sorafenib after surgery and confirmed on histological sections. CONCLUSION: This preclinical study shows that sorafenib did not impact on liver regeneration when ceased before surgery; however, administration after hepatectomy affected late liver regeneration.

Aseptic tissue necrosis and chronic inflammation after irrigation of penetrating hand wounds using Octenisept®

Penetrating hand wounds are common and these are managed by thorough debridement. However, stab wounds without evidence of divided structures are often treated with irrigation using antiseptic substances, antibiotic therapy, and immobilization. Octenisept® (Schülke & Mayr Ltd) is a widely used antiseptic agent for disinfection of acute or chronic wounds. It has a broad spectrum of antiseptic efficacy and has become an antiseptic of first choice in many hospitals. Within a few months, four patients presented to us with chronic inflammation and severe tissue necrosis after irrigation of penetrating hand wounds with Octenisept®. Repeated surgery and debridement was required in all patients. Wound healing was prolonged and patients had persisting oedema. Penetrating hand wounds must not be irrigated with Octenisept®.

In vitro evaluation of surface roughness, adhesion of periodontal ligament fibroblasts, and Streptococcus gordonii following root instrumentation with Gracey curettes and subsequent polishing with diamond-coated curettes

OBJECTIVES: The objective of the study was to evaluate the efficacy of an additional usage of a diamond-coated curette on surface roughness, adhesion of periodontal ligament (PDL) fibroblasts, and of Streptococcus gordonii in vitro. MATERIALS AND METHODS: Test specimens were prepared from extracted teeth and exposed to instrumentation with conventional Gracey curettes with or without additional use of diamond-coated curettes. Surface roughness (Ra and Rz) was measured before and following treatment. In addition, the adhesion of PDL fibroblasts for 72 h and adhesion of S. gordonii ATCC 10558 for 2 h have been determined. RESULTS: Instrumentation with conventional Gracey curettes reduced surface roughness (median Ra before: 0.36 μm/after: 0.25 μm; p < 0.001; median Rz before: 2.34 μm/after: 1.61 μm; p < 0.001). The subsequent instrumentation with the diamond-coated curettes resulted in a median Ra of 0.31 μm/Rz of 2.06 μm (no significance in comparison to controls). The number of attached PDL fibroblasts did not change following scaling with Gracey curettes. The additional instrumentation with the diamond-coated curettes resulted in a two-fold increase in the number of attached PDL fibroblasts but not in the numbers of adhered bacteria. CONCLUSIONS: Treatment of root surfaces with conventional Gracey curettes followed by subsequent polishing with diamond-coated curettes may result in a root surface which provides favorable conditions for the attachment of PDL fibroblasts without enhancing microbial adhesion. CLINICAL RELEVANCE: The improved attachment of PDL fibroblasts and the limited microbial adhesion on root surfaces treated with scaling with conventional Gracey curettes followed by subsequent polishing with diamond-coated curettes may favor periodontal wound healing.

Hyaluronic Acid as an Adjunct After Scaling and Root Planing - A Prospective Randomized Clinical Trial

Aim: The study was designed to determine the effect on clinical variables, subgingival bacteria and local immune response brought about by additional application of hyaluronan-containing gels in early wound healing after scaling and root planing (SRP). Material and Methods: In this randomised clinical study, data from 34 individuals with chronic periodontitis was evaluated after full-mouth SRP. In the test group (n = 17), hyaluronan gels in two molecular weights were additionally applied during the first two weeks after SRP. The control group (n = 17) was treated with SRP only. Probing depth (PD) and attachment level (AL) were recorded at baseline and after 3 and 6 months, and subgingival plaque and sulcus fluid samples were taken for microbiological and biochemical analysis. Results: In both groups, PD and AL were significantly reduced (p < 0.001). The changes in PD and the reduction of the numbers of pockets with PD ≥ 5mm were significantly higher in the test group after 3 (p = 0.014; p = 0.021) and 6 months (p = 0.046; p = 0.045). Six months after SRP, the counts of Treponema denticola were significantly reduced in both groups (both p = 0.043), those of Campylobacter rectus in the test group only (p = 0.028). Prevotella intermedia and Porphyromonas gingivalis increased in the control group. Conclusions: The adjunctive application of hyaluronan may have positive effects on probing depth reduction and may prevent recolonization by periodontopathogens.

Evaluation of chemically modified SLA implants (modSLA) biofunctionalized with integrin (RGD)- and heparin (KRSR)-binding peptides

Enhancing osseointegration through surface immobilization of multiple short peptide sequences that mimic extracellular matrix (ECM) proteins, such as arginine-glycine-aspartic acid (RGD) and lysine-arginine-serine-arginine (KRSR), has not yet been extensively explored. Additionally, the effect of biofunctionalizing chemically modified sandblasted and acid-etched surfaces (modSLA) is unknown. The present study evaluated modSLA implant surfaces modified with RGD and KRSR for potentially enhanced effects on bone apposition and interfacial shear strength during early stages of bone regeneration. Two sets of experimental implants were placed in the maxillae of eight miniature pigs, known for their rapid wound healing kinetics: bone chamber implants creating two circular bone defects for histomorphometric analysis on one side and standard thread configuration implants for removal torque testing on the other side. Three different biofunctionalized modSLA surfaces using poly-L-lysine-graft-poly(ethylene glycol) (PLL-g-PEG) as a carrier minimizing nonspecific protein adsorption [(i) 20 pmol cm⁻² KRSR alone (KRSR); or in combination with RGD in two different concentrations; (ii) 0.05 pmol cm⁻² RGD (KRSR/RGD-1); (iii) 1.26 pmol cm⁻² RGD (KRSR/RGD-2)] were compared with (iv) control modSLA. Animals were sacrificed at 2 weeks. Removal torque values (701.48-780.28 N mm), bone-to-implant contact (BIC) (35.22%-41.49%), and new bone fill (28.58%-30.62%) demonstrated no significant differences among treatments. It may be concluded that biofunctionalizing modSLA surfaces with KRSR and RGD derivatives of PLL-g-PEG polymer does not increase BIC, bone fill, or interfacial shear strength.

Advanced reconstructive technologies for periodontal tissue repair

Reconstructive therapies to promote the regeneration of lost periodontal support have been investigated through both preclinical and clinical studies. Advanced regenerative technologies using new barrier-membrane techniques, cell-growth-stimulating proteins or gene-delivery applications have entered the clinical arena. Wound-healing approaches using growth factors to target the restoration of tooth-supporting bone, periodontal ligament and cementum are shown to significantly advance the field of periodontal-regenerative medicine. Topical delivery of growth factors, such as platelet-derived growth factor, fibroblast growth factor or bone morphogenetic proteins, to periodontal wounds has demonstrated promising results. Future directions in the delivery of growth factors or other signaling models involve the development of innovative scaffolding matrices, cell therapy and gene transfer, and these issues are discussed in this paper.