Inorganic Antimicrobials in Exocrine Fluids

外分泌液中的无机抗菌剂

• 批准号: 7196380
• 负责人: MICHAEL T ASHBY
• 金额: $ 24.02万
• 依托单位: UNIVERSITY OF OKLAHOMA
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7196380
• 关键词: Inorganic; Antimicrobials; Exocrine; Fluids

DESCRIPTION (provided by applicant): The goal of this R21 project is to contribute to an understanding of the efficacies of hypohalite host defense factors toward pathogenic oral bacteria. Within the oral cavity, hypochlorite (OCI-) and hypothiocyanite (OSCN-) are produced by enzymes. Nevertheless, we have discovered a facile non-enzymic pathway that produces hypothiocyanite by oxidation of thiocyanate (SCN-) with hypochlorous acid (HOCI), a reaction that preserves the oxidizing equivalents of hypochlorite by transferring them to hypothiocyanite, a more discriminate biocide that is not lethal to mammalian cells. Remarkably little is known about the biocidal mechanisms of the hypohalites, due in part to their extraordinary reactivities and the fact that they produce cascades of derivative reactive intermediates with largely unknown physiologic properties. In addition to the complexities of the dynamic chemistry, the issue of biocidal mechanisms is further complicated by the heterogeneity of the oral cavity, where complex biofilms develop in chemically distinct environments. Recent studies have suggested that the genetic response of E. coli is different for the hypochlorite as compared to the hypothiocyanite system. Given that hypochlorite and hypothiocyanite apparently control spatially distinct regions of the oral cavity, but interracial regions near the gingival margin likely exhibit a concentration gradient of these hypohalites, we posit that these two biocides act in concert. The Specific Aims of this project are: 1) to develop protocols for assessing the biocidal efficacies of the hypochlorite and hypothiocyanite chemical systems and selected secondary derivatives toward a library of oral bacteria (and some controls); and 2) employing this protocol and the same library of oral bacteria, investigate synergistic effects of the primary and secondary biocides. These goals will be achieved through the application of whole-cell chemical-quench-flow and the introduction of chemical insults (some generated in real time) vis-a-vis a bioreactor system. We note that all of the experiments we describe in this R21 application involve planktonic cultures, which we believe is a logical first step before tackling the complexities of heterogeneous systems. Nevertheless, the methods that will be developed are expected to be adaptable to future studies that will include mixed-cultures and heterogeneous systems (including biofilms). Long-range Benefit: An understanding of the capacity of human defense mechanisms to control pathogenic oral microbes is essential for the improvement of therapies for oral infectious diseases. The ultimate objective of our research is the development of specific approaches to reduce pathogenic flora without altering the normal commensal (non-injurious) flora of the oral cavity.

描述(申请人提供)：这个R21项目的目标是帮助了解低盐宿主防御因子对致病口腔细菌的有效性。在口腔内，次氯酸盐(OCI-)和次硫氰酸盐(OSCN-)是由酶产生的。然而，我们已经发现了一种简便的非酶途径，通过硫氰酸盐(SCN-)与次氯酸(HOCI)的氧化生成次硫氰酸盐，该反应通过将次氯酸盐转移到次硫氰酸盐来保留次氯酸盐的氧化当量，次硫氰酸盐是一种更具区分性的杀菌剂，对哺乳动物细胞不致命。值得注意的是，人们对次卤酸盐的生物杀灭机理知之甚少，部分原因是它们具有非凡的反应性，而且它们会产生一系列具有未知生理性质的衍生反应中间体。除了动态化学的复杂性外，口腔的异质性使生物杀灭机制的问题进一步复杂化，口腔中复杂的生物膜在不同的化学环境中形成。最近的研究表明，与次硫氰酸盐体系相比，大肠杆菌对次氯酸盐的遗传反应是不同的。考虑到次氯酸盐和次硫氰酸盐显然控制着口腔的不同区域，但靠近牙龈边缘的界面区域可能显示出这些次氯酸盐的浓度梯度，我们假设这两种杀菌剂协同作用。该项目的具体目标是：1)制定评估次氯酸盐和次硫氰酸盐化学体系以及选定的二级衍生物对口腔细菌库(和一些对照)的杀菌效果的方案；以及2)使用该方案和相同的口腔细菌库，研究初级和次级杀菌剂的协同作用。这些目标将通过应用全细胞化学激冷流和引入针对生物反应器系统的化学侮辱(一些是实时产生的)来实现。我们注意到，我们在R21申请中描述的所有实验都涉及浮游植物培养，我们认为这是解决不同系统复杂性之前合乎逻辑的第一步。然而，预计将开发的方法将适用于未来包括混合培养和不同系统(包括生物膜)的研究。长期益处：了解人类防御机制控制致病口腔微生物的能力对于改进口腔传染病的治疗至关重要。我们研究的最终目标是开发特定的方法来减少致病菌群，而不改变口腔的正常共生(非损害性)菌群。