Antimicrobial and antibiofilm activity of pleurocidin against cariogenic microorganisms

Dental caries is a common oral bacterial infectious disease of global concern. Prevention and treatment of caries requires control of the dental plaque formed by pathogens such as Streptococcus mutans and Streptococcus sobrinus. Pleurocidin, produced by Pleuronectes americanus, is an antimicrobial peptide that exerts broad-spectrum activity against pathogenic bacteria and fungi. Moreover, pleurocidin shows less hemolysis and is less toxic than other natural peptides. In the present study, we investigated whether pleurocidin is an effective antibiotic peptide against common cariogenic microorganisms and performed a preliminary study of the antimicrobial mechanism. We assayed minimal inhibitory concentration (MIC), minimal bactericide concentration (MBC) and bactericidal kinetics and performed a spot-on-lawn assay. The BioFlux system was used to generate bacterial biofilms under controllable flow. Fluorescence microscopy and confocal laser scanning microscopy (CLSM) were used to analyze and observe biofilms. Scanning electron microscopy was used to observe the bacterial membrane. MIC and MBC results showed that pleurocidin had different antimicrobial activities against the tested oral strains. Although components of saliva could affect antimicrobial activity, pleurocidin dissolved in saliva still showed antimicrobial effects against oral microorganisms. Furthermore, pleurocidin showed a favorable killing effect against BioFlux flow biofilms in vitro. Our findings suggest that pleurocidin has the potential to kill dental biofilms and prevent dental caries.     

Use of laccase in pulp and paper industry

Laccase, through its versatile mode of action, has the potential to revolutionize the pulping and paper making industry. It not only plays a role in the delignification and brightening of the pulp but has also been described for the removal of the lipophilic extractives responsible for pitch deposition from both wood and nonwood paper pulps. Laccases are capable of improving physical, chemical, as well as mechanical properties of pulp either by forming reactive radicals with lignin or by functionalizing lignocellulosic fibers. Laccases can also target the colored and toxic compounds released as effluents from various industries and render them nontoxic through its polymerization and depolymerization reactions. This article reviews the use of both fungal and bacterial laccases in improving pulp properties and bioremediation of pulp and paper mill effluents.     

Molecular identification and diversity analysis of dental bacteria in diabetic and non-diabetic females from Saudi Arabia

Periodontal disease is a chronic infectious disease, which is characterized by the damaged dental hard tissue by lactic acid generated by microorganisms after the fermentation of carbohydrates rich diet. The risk of periodontal disease is known to be higher in diabetic patients. We compared the diversity of five commonly occurring dental bacteria including Porphyromonas gingivalis, Tannerella forsythia, Capnocytophaga ochracea, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans in 14 type-2 diabetic patients and equal numbers of healthy controls. The subgingival samples were collected using sterile paper points. We used 16S rRNA sequence specific primers for PCR-based identification of dental bacteria. Our results showed that A. actinomycetemcomitans was completely absent in control subjects but present in 43% of diabetic patients. C. ochracea was highly prevalent in diabetic patients (100%) as compared to controls (28.5%). The frequency of other three bacterial species was also higher in diabetic patients than control subjects. These findings indicate that dental bacteria are highly prevalent in subgingival pockets of diabetic patients. Therefore, proper monitoring of diabetic patients for dental care is important to prevent bacterial growth and its sequela in risky individuals. Further case-control studies using larger sample size would help in validating the association between oral diseases and diabetes.     

Adsorption of Basic violet 16 from aqueous solutions by waste sugar beet pulp: kinetic,thermodynamic, and equilibrium isotherm studies

Waste sugar beet pulp has been used as adsorbent for the removal of a hazardous cationic dye, Basic violet 16, from its aqueous solution. Adsorption of the dye was studied as function of time, pH of the solution, dosage of the adsorbent, sieve size of the particles, concentration of the dye, and temperature. The initial pH of the dye solution did not affect the chemistry of the dye molecule and the surface of beet pulp. Langmuir and Freundlich adsorption isotherms were successfully employed, and on the basis of these models, the thermodynamic parameters were evaluated. Adsorption of Basic violet 16 on beet pulp was found to be an exothermic reaction. Time contact studies showed that more than 80% adsorption of the dye is achieved in less than 1 h. Kinetics investigations confirmed both pseudo-first-order and pseudo-second-order behaviors; on the other hand, it shows that the intraparticle diffusion step is not the only rate-controlling step in all concentrations.     

拔除阻生智齿患者牙科焦虑的调查及分析

目的:了解综合医院口腔科拔除阻生智齿患者牙科焦虑的患病情况并进行相关因素分析。方法:采用牙科焦虑一般因素调查表、改良牙科焦虑量表(MDAS)及状态焦虑量表(S-AI)对300例口腔颌面外科门诊的拔除阻生智齿患者进行调查及评定,同时对引起牙科焦虑的相关因素进行分析。结果:拔除阻生智齿患者牙科焦虑的发生率为56.00%,有6项因素对牙科焦虑症的患病率有影响,差异有统计学意义(P<0.05),其中5项因素对MDAS得分影响较大。结论:牙科焦虑在拔除阻生智齿的患者中较普遍,有多种因素影响患者牙科焦虑的程度。     

Immunomodulatory Expression of Cathelicidins Peptides in Pulp Inflammation and Regeneration: An Update

The role of inflammatory mediators in dental pulp is unique. The local environment of pulp responds to any changes in the physiology that are highly fundamental, like odontoblast cell differentiation and other secretory activity. The aim of this review is to assess the role of cathelicidins based on their capacity to heal wounds, their immunomodulatory potential, and their ability to stimulate cytokine production and stimulate immune-inflammatory response in pulp and periapex. Accessible electronic databases were searched to find studies reporting the role of cathelicidins in pulpal inflammation and regeneration published between September 2010 and September 2020. The search was performed using the following databases: Medline, Scopus, Web of Science, SciELO and PubMed. The electronic search was performed using the combination of keywords “cathelicidins” and “dental pulp inflammation”. On the basis of previous studies, it can be inferred that LL-37 plays an important role in odontoblastic cell differentiation and stimulation of antimicrobial peptides. Furthermore, based on these outcomes, it can be concluded that LL-37 plays an important role in reparative dentin formation and provides signaling for defense by activating the innate immune system.     

下颌种植覆盖义齿的生物力学研究进展

口腔生物力学是用生物力学的概念和方法,研究口腔医学中的有关基础性科学问题、解决口腔医学中的临床实际问题、发展口腔临床技术的一门学科。在口腔正畸学、修复学、种植学及口腔颌面外科学等领域存在着大量的生物力学问题,生物力学已成为口腔医学的基础科学之一。传统全口义齿修复常常会出现固位稳定差、咀嚼效率低、患者有疼痛感、适应时间长等情况,很大程度上不能满足患者的修复要求。种植覆盖义齿对于下颌牙槽嵴严重吸收的患者,效果尤为明显。种植覆盖义齿是义齿与种植体之间以不同的附着体作为连接,形成患者可以自行摘戴的种植体支持的覆盖义齿修复。下颌种植覆盖义齿因其能有效地提高下半口义齿的固位性和稳定性、显著提高了患者的咀嚼效率,目前已成为修复下颌牙槽骨严重吸收的无牙颌患者的有效修复方法。本文针对下颌种植覆盖义齿的生物力学研究进展作一综述。     

Using LCA to examine greenhouse gas abatement policy

The site-generic approach currently adopted by the Life Cycle Assessment (LCA) methodology introduces uncertainties into the impact assessment phase of an LCA study. These uncertainties are greatest for localised and short-lived problems but are less significant for long lasting, cumulative environmental effects. Indeed, the reliability of LCA results is high for problems that manifest at a global scale. Nevertheless, even though these results are considered accurate, it is still often unclear as to their relevance in terms of policy development and decision-making. Therefore, this paper demonstrates how LCA can be used to determine the efficacy of policies aimed at reducing a product system’s contribution to global environmental problems. We accomplish this aim by presenting a case study that evaluates the greenhouse gas contributions of each stage in the life cycle of containerboard packaging and the potential impact on emissions of various policy options available to decision makers. Our analysis showed that in general the most useful strategy was to recycle the used packaging. However, our analysis also indicated that when measures are taken to eliminate sources of methane emissions and encourage the use of plantation timber then recycling is no longer beneficial from a greenhouse perspective. This is because the process energy required in the form of gas and electricity is substantially greater for containerboard manufactured from recycled material than it is for virgin fibre.     

Some properties of eucalyptus kraft pulp treated with xylanase from Aspergillus niger

An Aspergillus niger isolate produced about 2500nkat xylanase/ml when cultivated in a medium containing 3% xylose. Application of the crude xylanolytic preparation to unbleached eucalyptus kraft pulp resulted in a decreased kappa number and increased brightness. Handsheets made from the xylanase-treated pulp after ECF bleaching retained good structural and mechanical characteristics.