Search

Adhesins facilitate bacterial colonization and invasion of host tissues and are considered virulence factors, but their impact on immune-mediated damage as a driver of pathogenesis remains unclear. Yersinia pseudotuberculosis encodes for a multivalent adhesion molecule (MAM), a mammalian cell entry (MCE) family protein and adhesin. MAMs are widespread in Gram-negative bacteria and enable enteric bacteria to colonize epithelial tissues. Their role in bacterial interactions with the host innate immune system and contribution to pathogenicity remains unclear. Here, we investigated howY. pseudotuberculosis MAM contributes to pathogenesis during infection of the Galleria mellonella insect model. We show that Y. pseudotuberculosis MAM is required for efficient bacterial binding and uptake by hemocytes, the host phagocytes. Y. pseudotuberculosis interactions with insect and mammalian phagocytes are determined by bacterial and host factors. Loss of MAM, and deficient microbe–phagocyte interaction, increased pathogenesis in G. mellonella. Diminished phagocyte association also led to increased bacterial clearance. Furthermore, Y. pseudotuberculosis that failed to engage phagocytes hyperactivated humoral immune responses, most notably melanin production. Despite clearing the pathogen, excessive melanization also increased phagocyte death and host mortality. Our findings provide a basis for further studies investigating how microbe- and host-factors integrate to drive pathogenesis in a tractable experimental system.

Abstract The effects of fluorodeoxyglucose conjugated iron oxide magnetic nanoparticles (FDGMNP) on macrophages are presented using a yeast substrate. Iron oxide magnetic nanoparticles (MNP) were synthesized by partially reducing FeCl3, then conjugated with (3-aminopropyl) triethoxysilane (APTES) after silication with tetraethyl orthosilicate. Silanated MMP nanoparticles were combined with fluorodeoxyglucose (FDG). Fluorodeoxyglucose iron oxide magnetic nanoparticles (FDGMNP) and its unconjugated control (MNP) were added (1mL) to the cells from the murine macrophage-like, Abelson murine leukemia virus transformed cell line RAW 264.7 (American Type Culture Collection number TIB-71) cell culture wells at different concentrations from 90-3.6 μg/mL. Cells were placed on the magnet plate for 30 min before incubating at 37°C, 5% CO2 overnight. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide tetrazolium) assay was performed to measure cell viability. Our results demonstrate that iron based nanoparticles can be linked to macrophages (elements of the immune system that attack bacteria) without the function of the macrophages being affected, ie no detrimental effects to the macrophages were evident in these experiments. We conclude that neither FDGMNP nor MNP had a detrimental effect on macrophage function.

Vibrio parahaemolyticus is an emerging bacterial pathogen which colonizes the gastrointestinal tract and can cause severe enteritis and bacteraemia. During infection, V. parahaemolyticus primarily attaches to the small intestine, where it causes extensive tissue damage and compromises epithelial barrier integrity. We have previously described that Multivalent Adhesion Molecule (MAM) 7 contributes to initial attachment of V. parahaemolyticus to epithelial cells. Here we show that the bacterial adhesin, through multivalent interactions between surface-induced adhesin clusters and phosphatidic acid lipids in the host cell membrane, induces activation of the small GTPase RhoA and actin rearrangements in host cells. In infection studies with V. parahaemolyticus we further demonstrate that adhesin-triggered activation of the ROCK/LIMK signaling axis is sufficient to redistribute tight junction proteins, leading to a loss of epithelial barrier function. Taken together, these findings show an unprecedented mechanism by which an adhesin acts as assembly platform for a host cellular signaling pathway, which ultimately facilitates breaching of the epithelial barrier by a bacterial pathogen.

Magnetic nanoparticle-based gene transfection has been shown to be an effective, non-viral technique for delivery of both plasmid DNA and siRNA into cells in culture. It has several advantages over other non-viral delivery techniques, such as short transfection times and high cell viability. These advantages have been demonstrated in a number of primary cells and cell lines. Here we report that oscillating magnet array-based nanomagnetic transfection significantly improves transfection efficiency in both human prenatal cardiac progenitor cells and adult cardiomyocytes when compared to static magnetofection, cationic lipid reagents and electroporation, while maintaining high cell viability. In addition, transfection of adult cardiomyocytes was improved further by seeding the cells onto Collagen I-coated plates, with transfection efficiencies of up to 49% compared to 24% with lipid reagents and 19% with electroporation. These results demonstrate that oscillating nanomagnetic transfection far outperforms other non-viral transfection techniques in these important cells.

Integrin-mediated phagocytosis, an important physiological activity undertaken by professional phagocytes, requires bidirectional signalling to/from αMβ2 integrin and involves Rap1 and Rho GTPases. The action of Rap1 and the cytoskeletal protein talin in activating αMβ2 integrins, in a RIAM-independent manner, has been previously shown to be critical during phagocytosis in mammalian phagocytes. However, the events downstream of Rap1 are not clearly understood. Our data demonstrate that one potential Rap1 effector, Regulator of G-Protein Signalling-14 (RGS14), is involved in activating αMβ2. Exogenous expression of RGS14 in COS-7 cells expressing αMβ2 results in increased binding of C3bi-opsonised sheep red blood cells. Consistent with this, knock-down of RGS14 in J774.A1 macrophages results in decreased association with C3bi-opsonised sheep red blood cells. Regulation of αMβ2 function occurs through the R333 residue of the RGS14 Ras/Rap binding domain (RBD) and the F754 residue of β2, residues previously shown to be involved in binding of H-Ras and talin1 head binding prior to αMβ2 activation, respectively. Surprisingly, overexpression of talin2 or RAPL had no effect on αMβ2 regulation. Our results establish for the first time a role for RGS14 in the mechanism of Rap1/talin1 activation of αMβ2 during phagocytosis.

Gene delivery technologies to introduce foreign genes into highly differentiated mammalian cells have improved significantly over the last few decades. Relatively new techniques such as magnetic nanoparticle-based gene transfection technology are showing great promise in terms of its high transfection efficiency and wide-ranging research applications. We have developed a novel gene delivery technique, which uses magnetic nanoparticles moving under the influence of an oscillating magnetic array. Herein we successfully introduced short interfering RNA (siRNA) against green fluorescent protein (GFP) or actin into stably-transfected GFP-HeLa cells or wild-type HeLa and rat aortic smooth muscle cells, respectively. This gene silencing technique occurred in a dose- and cell density- dependent manner, as reflected using fluorescence intensity and adhesion assays. Furthermore, using endocytosis inhibitors, we established that these magnetic nanoparticle-nucleic acid complexes, moving across the cell surface under the influence of an oscillating magnet array, enters into the cells via the caveolae-mediated endocytic pathway.

Caries indices, the basis of epidemiologic caries measures, are not easily obtained in clinical settings. This study's objective was to design, test, and validate an automated program (Valid Electronic Health Record Dental Caries Indices Calculator Tool [VERDICT]) to calculate caries indices from an electronic health record (EHR). Synthetic use case scenarios and actual patient cases of primary, mixed, and permanent dentition, including decayed, missing, and filled teeth (DMFT/dmft) and tooth surfaces (DMFS/dmfs) were entered into the EHR. VERDICT measures were compared to a previously validated clinical electronic data capture (EDC) system and statistical program to calculate caries indices. Four university clinician-researchers abstracted EHR caries exam data for 45 synthetic use cases into the EDC and post-processed with SAS software creating a gold standard to compare the -VERDICT-derived caries indices. Then, 2 senior researchers abstracted EHR caries exam data and calculated caries indices for 24 patients, allowing further comparisons to VERDICT indices. Agreement statistics were computed among abstractors, and discrepancies were resolved by consensus. Agreement statistics between the 2 final-phase abstractors and the VERDICT measures showed extremely high concordance: Lin's concordance coefficients (LCCs) >0.99 for dmfs, dmft, DS, ds, DT, dt, ms, mt, FS, fs, FT, and ft; LCCs >0.95 for DMFS and DMFT; and LCCs of 0.92-0.93 for MS and MT. Caries indices, essential to developing primary health outcome measures for research, can be reliably derived from an EHR using VERDICT. Using these indices will enable population oral health management approaches and inform quality improvement efforts., (© 2019 S. Karger AG, Basel.)

The paradigm shift in understanding the etiology, prevention, and treatment of dental caries requires an understanding of the dental products that are currently available to assist the clinician in prudent recommendations for patient interventions. The purpose of this review is to present the evidence base for current products and those that have recently appeared on the market.

The aim of this article is to present a practical caries risk assessment procedure and form for patients who are age 6 through adult. The content of the form and the procedures have been validated by outcomes research after several years of experience using the factors and indicators that are included.

This article seeks to provide a practical, everyday clinical guide for managing dental caries based upon risk group assessment. It is based upon the best evidence at this time and can be used in planning effective caries management for any patient. In addition to a comprehensive restorative treatment plan, each patient should have a comprehensive caries management treatment plan. Some sample treatment plans are included.

The ethical ground for restoration (returning a patient to healthy form and function) differs from enhancement (using medical means to improve appearance). Physicians and dentists who argue that enhancements improve self-esteem must reconcile this claim with the fact that they are not licensed to practice psychology. The extreme views are that doctors either should provide cosmetic services as requested by patients or they should not. The middle position is that doctors must retain their fiduciary position of trust based on professional judgment and advocating for patients' health interests. Patient health always outweighs patients' cosmetic desires.

Ethical dilemmas arise when it is not possible to simultaneously optimize conflicting values, each of which independently is worthy. This paper analyzes three cases where patients' autonomy is in conflict with dentists' professional judgments about their own practice patterns and what is in the best interests of patients' oral health. The hierarchy of values proposed by Ozar and Sokol is a valuable aid in addressing such dilemmas, but the dentist must still engage in a detailed analysis of the situation.

The general dentist has a unique role as the gatekeeper of dental care. In this role, the generalist is called upon to be the primary diagnostician and is charged with the responsibility for triaging patients. Classification systems devised by many of the dental specialties are valuable tools for the diagnosis of diseases and conditions specific to the specialty, but no classifications have been directed to the general dentist. This paper describes a system being used at the University of California at San Francisco School of Dentistry that enables the general dentist to classify a patient's stomatognathic system as either physiologic or nonphysiologic and then guides the clinician toward appropriate treatment decisions.