4138 Development of an Antibiofilm Resorbable Membrane for Treating Peri-implantitis

OBJECTIVES/GOALS: Peri-implantitis is the inflammation of peri-implant mucosa and subsequent loss of supporting bone. Its treatment is only <40% successful mainly due to persistent bacterial infection. The goal of this project is to increase success rates by developing a robust antibiofilm multi-biomolecular membrane that can be placed around implant surfaces. METHODS/STUDY POPULATION: A collagen membrane was soaked in the antimicrobial peptide GL13K solution overnight to form an interpenetrating fibrillary network. The nanostructure of the membrane was imaged with scanning electron microscope (SEM). The hydrophobicity of the membrane was analyzed by water contact angle (WCA) measurements. The biodegradability was tested in a 0.01 mg/mL Type I collagenase solution for up to 5 weeks. The antimicrobial activity of the membrane was assessed with Gram-positive oral bacteria Streptococcus gordonii. The cytotoxicity was evaluated by culturing human gingival fibroblasts (HGF), and the osteogenesis was assessed using preosteoblasts MC3T3. Pure collagen membrane was used as the control. Statistical significance (p<0.05) was determined by one-way ANOVA with Tukey’s HSD test. RESULTS/ANTICIPATED RESULTS: The antimicrobial peptide GL13K self-assembled to short fibrils (< 1 µm long), which entangled with the larger collagen fibers (around 200 nm in diameter). The collagen fibers presented characteristic periodic banding structures, which provided biomimetic cues for cell behavior as extracellular matrix. The interpenetrated GL13K fibrils turned the highly hydrophilic collagen membrane to a hydrophobic membrane (WCA = 135 °) and significantly reduced the rate of degradation by collagenases. The developed membrane was efficient in preventing the attachment of S. gordonii. A large portion of the attached bacteria was killed on the surface of the membrane. The incorporation of GL13K did not affect the cytocompatibility of the membrane for HGF. DISCUSSION/SIGNIFICANCE OF IMPACT: We developed an antibiofilm membrane with interpenetrating collagen and antimicrobial peptide fibrils. The strong antimicrobial activity and low cytotoxicity support its further translational evaluation as scaffolds for increasing success rate in treating peri-implantitis.

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Osteoconductive properties of upside-down bilayer collagen membranes in rat calvarial defects

International Journal of Implant Dentistry ◽

10.1186/s40729-021-00333-y ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Balazs Feher ◽

Karol Ali Apaza Alccayhuaman ◽

Franz Josef Strauss ◽

Jung-Seok Lee ◽

Stefan Tangl ◽

...

Keyword(s):

Bone Regeneration ◽

Soft Tissues ◽

Collagen Fibers ◽

Collagen Membrane ◽

Bony Defect ◽

Dense Layer ◽

Type I ◽

Trabecular Thickness ◽

Defect Area ◽

Collagen Membranes

Abstract Background Bilayer collagen membranes are routinely used in guided bone/tissue regeneration to serve as osteoconductive scaffolds and prevent the invasion of soft tissues. It is recommended to place the membranes with their dense layer towards the soft tissue and their porous layer towards the bony defect area. However, evidence supporting this recommendation is lacking. This study aimed to determine whether the alignment of bilayer collagen membranes has an effect on bone regeneration. Methods In two groups of ten male Sprague-Dawley rats each, a 5-mm calvarial defect was created. Thereafter, the defect was randomly covered with a bilayer, resorbable, pure type I and III collagen membrane placed either regularly or upside-down (i.e., dense layer towards bone defect). After 4 weeks of healing, micro-computed tomography (μCT), histology, and histomorphometry of the inner cylindrical region of interest (4.5 mm in diameter) were performed to assess new bone formation and the consolidation of the collagen membrane in the defect area. Results Quantitative μCT showed similar bone volume (median 8.0 mm3, interquartile range 7.0–10.0 vs. 6.2 mm3, 4.3–9.4, p = 0.06) and trabecular thickness (0.21 mm, 0.19–0.23 vs. 0.18 mm, 0.17–0.20, p = 0.03) between upside-down and regular placement, both leading to an almost complete bony coverage. Histomorphometry showed comparable new bone areas between the upside-down and regularly placed membranes, 3.9 mm2 (2.7–5.4) vs. 3.8 mm2 (2.2–4.0, p = 0.31), respectively. Both treatment groups revealed the same regeneration patterns and spatial distribution of bone with and without collagen fibers, as well as residual collagen fibers. Conclusions Our data support the osteoconductive properties of collagen membranes and suggest that bone regeneration is facilitated regardless of membrane layer alignment.

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Evaluation of Relative Efficacy of β-Tricalcium Phosphate with and without Type I Resorbable Collagen Membrane in Periodontal Infrabony Defects: A Clinical and Radiographic Study

The Journal of Contemporary Dental Practice ◽

10.5005/jp-journals-10024-1299 ◽

2013 ◽

Vol 14 (2) ◽

pp. 193-201 ◽

Cited By ~ 3

Author(s):

R Padma ◽

D Trinath Kishore ◽

Tushar Bandiwadekar ◽

Surangama Debunath ◽

Profulla LNU ◽

...

Keyword(s):

Tricalcium Phosphate ◽

Statistical Significance ◽

Collagen Membrane ◽

Type I ◽

Clinical Parameters ◽

Relative Efficacy ◽

Radiographic Study ◽

Experimental Site ◽

Radiographic Findings ◽

Infrabony Defects

ABSTRACT Background and objectives To compare clinically and radiographically, the regenerative potential of a β-tricalcium phosphate bone graft, Cerasorb® with and without a bioresorbable type I collagen membrane, BioMend ExtendTM, in treating periodontal infrabony osseous defects. Materials and methods A total of 20 sites from 10 patients showing bilateral infrabony defects were selected and selected sites were randomly divided into experimental site A (Cerasorb®) and experimental site B (Cerasorb® and BioMend ExtendTM) by using split mouth design. The clinical parameters like plaque index, gingival index, probing pocket depth, clinical attachment level and gingival recession were recorded at baseline, 6 weeks, 3, 6 and 9 months. Radiographic evaluation (Linear CADIA) at 6 and 9 months; and intrasurgical measurements at baseline and 9 months were carried out to evaluate the defect fill, change in alveolar crest height and defect resolution. Results Significant reduction in all clinical parameters was observed in both the groups. On comparison no statistical significance was observed between the two groups. Radiographically, in site A there was significant defect fill of 78.4 and 97.2% at 6 and 9 months respectively. Whereas in site B reduction was 78.4 and 97.2% at 6 and 9 months respectively. After surgical re-entry, there was significant defect fill of 89.2 and 74% in both groups. Interpretation and conclusion Individually both the graft and membrane have shown promising results in the management of periodontal intrabony defects. But the added benefit by combining Cerasorb® with BioMend ExtendTM was not observed statistically in both clinical radiographic findings. How to cite this article Kishore DT, Bandiwadekar T, Padma R, Debunath S, Profulla, Reddy A. Evaluation of Relative Efficacy of β-Tricalcium Phosphate with and without Type I Resorbable Collagen Membrane in Periodontal Infrabony Defects: A Clinical and Radiographic Study. J Contemp Dent Pract 2013;14(2): 193-201.

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Antimicrobial Activity of Protamine-Loaded Calcium Phosphates against Oral Bacteria

Materials ◽

10.3390/ma12172816 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2816 ◽

Cited By ~ 2

Author(s):

Masashi Fujiki ◽

Kodai Abe ◽

Tohru Hayakawa ◽

Takatsugu Yamamoto ◽

Mana Torii ◽

...

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Peptide ◽

Streptococcus Mutans ◽

Biofilm Formation ◽

Calcium Phosphates ◽

Oral Bacteria ◽

The Other ◽

Dental Material ◽

Planktonic Bacteria ◽

Surrounding Environment

Protamine is an antimicrobial peptide extracted from fish. In this study, we loaded protamine onto dicalcium phosphate anhydride (DCPA), a dental material. Protamine was loaded by stirring DCPA into a protamine solution. To explore the antimicrobial activity of the materials, we cultivated Streptococcus mutans on fabricated discs for 24 h. When S. mutans was cultivated on the discs under no sucrose conditions, the loaded protamine was not released, and the ratio of dead bacteria increased on the surface of P (125) DCPA (half of the saturated level of protamine (125 ppm protamine) was loaded). Aside from P (500) DCPA (saturated level of protamine was loaded), some protamine was released, and the number of planktonic bacteria in the supernatant decreased. Using medium containing 1% sucrose, the release of protamine was promoted from P (125) DCPA due to lowered pH. However, lowering of the pH decreased the antimicrobial activity of protamine. On the other hand, P (500) DCPA released protamine before the pH was lowered, and biofilm formation was inhibited. The loaded protamine expressed antimicrobial activity, both on the surface of the materials and in the surrounding environment. The interaction of loaded protamine with calcium phosphates could promote the application of protamine in the dental field.

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Methionine-Specific Staining of Collagen

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005408x ◽

1982 ◽

Vol 40 ◽

pp. 294-295

Author(s):

E.M. Kuhn ◽

K.D. Marenus ◽

M. Beer

Keyword(s):

Amino Acids ◽

Collagen Fibers ◽

Type Iii Collagen ◽

Type I ◽

Electron Microscopic ◽

Good Correspondence ◽

Specific Staining ◽

Type Iii ◽

Different Types ◽

Sulfur Containing

Fibers composed of different types of collagen cannot be differentiated by conventional electron microscopic stains. We are developing staining procedures aimed at identifying collagen fibers of different types.Pt(Gly-L-Met)Cl binds specifically to sulfur-containing amino acids. Different collagens have methionine (met) residues at somewhat different positions. A good correspondence has been reported between known met positions and Pt(GLM) bands in rat Type I SLS (collagen aggregates in which molecules lie adjacent to each other in exact register). We have confirmed this relationship in Type III collagen SLS (Fig. 1).

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Linkage Disequilibrium in Domestic Sheep

Genetics ◽

10.1093/genetics/160.3.1113 ◽

2002 ◽

Vol 160 (3) ◽

pp. 1113-1122

Author(s):

A F McRae ◽

J C McEwan ◽

K G Dodds ◽

T Wilson ◽

A M Crawford ◽

...

Keyword(s):

Linkage Disequilibrium ◽

Type I Error ◽

Statistical Significance ◽

Domestic Sheep ◽

Type I ◽

Single Nucleotide ◽

Microsatellite Genotype ◽

Marker Distance ◽

The Relationship ◽

Two Populations

Abstract The last decade has seen a dramatic increase in the number of livestock QTL mapping studies. The next challenge awaiting livestock geneticists is to determine the actual genes responsible for variation of economically important traits. With the advent of high density single nucleotide polymorphism (SNP) maps, it may be possible to fine map genes by exploiting linkage disequilibrium between genes of interest and adjacent markers. However, the extent of linkage disequilibrium (LD) is generally unknown for livestock populations. In this article microsatellite genotype data are used to assess the extent of LD in two populations of domestic sheep. High levels of LD were found to extend for tens of centimorgans and declined as a function of marker distance. However, LD was also frequently observed between unlinked markers. The prospects for LD mapping in livestock appear encouraging provided that type I error can be minimized. Properties of the multiallelic LD coefficient D′ were also explored. D′ was found to be significantly related to marker heterozygosity, although the relationship did not appear to unduly influence the overall conclusions. Of potentially greater concern was the observation that D′ may be skewed when rare alleles are present. It is recommended that the statistical significance of LD is used in conjunction with coefficients such as D′ to determine the true extent of LD.

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Comparison of a Short Linear Antimicrobial Peptide with Its Disulfide-Cyclized and Cyclotide-Grafted Variants against Clinically Relevant Pathogens

Microorganisms ◽

10.3390/microorganisms9061249 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1249

Author(s):

Johannes Koehbach ◽

Jurnorain Gani ◽

Kai Hilpert ◽

David J Craik

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Peptide ◽

Human Serum ◽

World Health ◽

Resistant Bacteria ◽

Moderate Activity ◽

Antimicrobial Compounds ◽

Strong Activity ◽

Linear Peptide ◽

Linear Version

According to the World Health Organization (WHO) the development of resistance against antibiotics by microbes is one of the most pressing health concerns. The situation will intensify since only a few pharmacological companies are currently developing novel antimicrobial compounds. Discovery and development of novel antimicrobial compounds with new modes of action are urgently needed. Antimicrobial peptides (AMPs) are known to be able to kill multidrug-resistant bacteria and, therefore, of interest to be developed into antimicrobial drugs. Proteolytic stability and toxicities of these peptides are challenges to overcome, and one strategy frequently used to address stability is cyclization. Here we introduced a disulfide-bond to cyclize a potent and nontoxic 9mer peptide and, in addition, as a proof-of-concept study, grafted this peptide into loop 6 of the cyclotide MCoTI-II. This is the first time an antimicrobial peptide has been successfully grafted onto the cyclotide scaffold. The disulfide-cyclized and grafted cyclotide showed moderate activity in broth and strong activity in 1/5 broth against clinically relevant resistant pathogens. The linear peptide showed superior activity in both conditions. The half-life time in 100% human serum was determined, for the linear peptide, to be 13 min, for the simple disulfide-cyclized peptide, 9 min, and, for the grafted cyclotide 7 h 15 min. The addition of 10% human serum led to a loss of antimicrobial activity for the different organisms, ranging from 1 to >8-fold for the cyclotide. For the disulfide-cyclized version and the linear version, activity also dropped to different degrees, 2 to 18-fold, and 1 to 30-fold respectively. Despite the massive difference in stability, the linear peptide still showed superior antimicrobial activity. The cyclotide and the disulfide-cyclized version demonstrated a slower bactericidal effect than the linear version. All three peptides were stable at high and low pH, and had very low hemolytic and cytotoxic activity.

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Assembly of Type I Collagen on PVA Film Induced by Glutaraldehyde Vapor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.284-286.1794 ◽

2011 ◽

Vol 284-286 ◽

pp. 1794-1799 ◽

Cited By ~ 1

Author(s):

Yu Lu Wang ◽

Xue Pin Liao ◽

Bi Shi

Keyword(s):

Network Structure ◽

Type I Collagen ◽

Collagen Fibers ◽

Type I ◽

Collagen Concentration ◽

Collagen Molecules ◽

Induced Reaction ◽

Calf Skin

Type I collagen was isolated from calf skin and its assembly on PVA film induced by glutaraldehyde vapor was investigated. It was found that the collagen molecules were firstly orientationally assembled into collagen fibers under the inducement of glutaraldehyde vapor. Then the collagen fibers could be further aggregated into novel network structure in proper conditions of the induced reaction. The morphology of the assembled collagen fibers was depended on induced time and concentration of collagen. The network arrangement could be obtained after being induced for 72h when collagen concentration was 2.5mg/ml. At higher concentration of collagen (5 mg/ml), the collagen fibers with larger dimension were obtained, but the growth of fibers was almost in one direction.

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Dentin-Derived-Barrier Membrane in Guided Bone Regeneration: A Case Report

Materials ◽

10.3390/ma14092166 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2166

Author(s):

Jeong-Kui Ku ◽

In-Woong Um ◽

Mi-Kyoung Jun ◽

Il-hyung Kim

Keyword(s):

Case Report ◽

Bone Regeneration ◽

Guided Bone Regeneration ◽

Successful Outcome ◽

Collagen Membrane ◽

Type I ◽

Barrier Membrane ◽

Dentin Matrix ◽

Demineralized Dentin Matrix ◽

Demineralized Dentin

An autogenous, demineralized, dentin matrix is a well-known osteo-inductive bone substitute that is mostly composed of type I collagen and is widely used in implant dentistry. This single case report describes a successful outcome in guided bone regeneration and dental implantation with a novel human-derived collagen membrane. The authors fabricated a dentin-derived-barrier membrane from a block-type autogenous demineralized dentin matrix to overcome the mechanical instability of the collagen membrane. The dentin-derived-barrier acted as an osteo-inductive collagen membrane with mechanical and clot stabilities, and it replaced the osteo-genetic function of the periosteum. Further research involving large numbers of patients should be conducted to evaluate bone forming capacity in comparison with other collagen membranes.

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Biomarker-oriented study of durvalumab in combination with olaparib and paclitaxel in gastric cancer: A phase 2 trial-in-progress.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.15_suppl.tps4153 ◽

2021 ◽

Vol 39 (15_suppl) ◽

pp. TPS4153-TPS4153

Author(s):

Tae Yong Kim ◽

Jee Sun Yoon ◽

Ah-Rong Nam ◽

Ju-Hee Bang ◽

Kyoung Seok Oh ◽

...

Keyword(s):

Gastric Cancer ◽

Dna Damage ◽

Immune Modulation ◽

Statistical Significance ◽

Parp Inhibitor ◽

Phase Iii ◽

Type I ◽

Second Line ◽

Absolute Increase ◽

Combination Methods

TPS4153 Background: Olaparib (PARP inhibitor) leads to DNA damage and cell death. In phase III study (GOLD), olaparib plus paclitaxel did not improve overall survival (OS) compared with paclitaxel in second-line gastric cancer (GC) patients with statistical significance, even though there was absolute increase of OS (Lancet Oncol 2017). This highlights the importance of biomarker-based patient selection. The changes of tumor microenvironment by paclitaxel/olaparib have not been explored. Besides DNA damage, olaparib induces positive or negative immune modulation by recruiting T cells, promoting type I interferon and upregulating PD-L1, which suggests anti-PD (L1) inhibitor plus olaparib could enhance anti-tumor immunity. Combination of Anti-PD-1 agents with chemotherapy showed a good clinical efficacy in first-line of GC compared with chemotherapy alone (Checkmate 649). Based on these findings, the combination of paclitaxel/olaparib/anti-PD(L1)1 inhibitor, with different mode of actions, might enhance antitumor activity. This is phase II study of paclitaxel/olaparib/durvalumab combination in second-line GC patients, to find out immune modulation effects by paclitaxel/olaparib combination, and to see the efficacy, safety, optimal biomarkers for this combination. Methods: All patients with histologically confirmed unresectable GC have failed to prior one chemotherapy and measurable lesion. Prior exposure to anti-PD(L1)1, PARP inhibitor is excluded. At 1st cycle, paclitaxel (80 mg/m2) on D1, 8 and 15 and olaparib (150 mg bid) on D1-28 is administered. Pre-treatment biopsy and after first cycle biopsy is done. From second cycle, durvalumab 1500 mg on D1 every 4 weeks is added. At the time of disease progression, tumor biopsy is mandatory. Blood samples for biomarkers should be obtained every cycles. Response evaluation is performed after first 3 cycles and repeated every 2 cycles. Primary endpoint is the disease control rate (the percentage of patients who have achieved complete or partial remission, stable disease based on RECIST v1). Key secondary endpoints are overall response rate, progression-free survival, OS, quality of life and safety. Clinical trial information: NCT03579784.

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The Designer Antimicrobial Peptide A-hBD-2 Facilitates Skin Wound Healing by Stimulating Keratinocyte Migration and Proliferation

Cellular Physiology and Biochemistry ◽

10.1159/000495320 ◽

2018 ◽

Vol 51 (2) ◽

pp. 647-663 ◽

Cited By ~ 2

Author(s):

Bobin Mi ◽

Jing Liu ◽

Yi Liu ◽

Liangcong Hu ◽

Yukun Liu ◽

...

Keyword(s):

Antimicrobial Activity ◽

Wound Healing ◽

Antimicrobial Peptide ◽

Structural Stability ◽

Cell Counting ◽

Sprague Dawley ◽

Skin Wound Healing ◽

High Sodium

Background/Aims: Antimicrobial peptides are effective promoters of wound healing but are susceptible to degradation. In this study, we replaced the GIGDP unit on the N-terminal of the endogenous human antimicrobial peptide hBD-2 with APKAM to produce A-hBD-2 and analyzed the effect on wound healing both in vitro and in vivo. Methods: The effects of A-hBD-2 and hBD-2 on cytotoxicity and proliferation in keratinocytes were assessed by Cell Counting Kit-8 assay. The structural stability and antimicrobial activity of hBD-2 and A-hBD-2 were evaluated against Staphylococcus aureus. RNA and proteins levels were evaluated by real-time PCR and western blotting, respectively. Cell migration was evaluated using a transwell assay. Cell cycle analysis was performed by flow cytometry. Wound healing was assessed in Sprague-Dawley rats. Epidermal thickness was evaluated by hematoxylin and eosin staining. Results: We found that hBD-2 exhibited cytotoxicity at high concentrations and decreased the structural stability in the presence of high sodium chloride concentrations. A-hBD-2 exhibited increased structural stability and antimicrobial activity, and had lower cytotoxicity in keratinocytes. A-hBD-2 increased the migration and proliferation of keratinocytes via phosphorylation of EGFR and STAT3 and suppressed terminal differentiation of keratinocytes. We also found that A-hBD-2 elicited mobilization of intracellular Ca2+ and stimulated keratinocytes to produce pro- and anti-inflammatory cytokines and chemokines via phospholipase C activation. Furthermore, A-hBD-2 promoted wound healing in vivo. Conclusion: Our data suggest that A-hBD-2 may be a promising candidate therapy for wound healing.

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