No abstract

Sterile protection against malaria infection can be achieved through vaccination of mice and humans with whole Plasmodium spp. parasites. One such method, known as infection–treatment–vaccination (ITV), involves immunization with wild type sporozoites (spz) under drug coverage. In this work, we used the different effects of antimalarial drugs chloroquine (CQ) and artesunate (AS) on blood stage (BS) parasites to dissect the stage-specific immune responses in mice immunized with Plasmodium yoelii spz under either drug, as well as their ability to protect mice against challenge with spz or infected RBCs (iRBCs). Whereas CQ-ITV induced sterile protection against challenge with both spz and iRBCs, AS-ITV only induced sterile protection against spz challenge. Importantly, AS-ITV delayed the onset of BS infection, indicating that both regimens induced cross-stage immunity. Moreover, both CQ- and AS-ITV induced CD8+ T cells in the liver that eliminated malaria-infected hepatocytes in vitro, as well as Abs that recognized pre-erythrocytic parasites. Sera from both groups of mice inhibited spz invasion of hepatocytes in vitro, but only CQ-ITV induced high levels of anti-BS Abs. Finally, passive transfer of sera from CQ-ITV–treated mice delayed the onset of erythrocytic infection in the majority of mice challenged with P. yoelii iRBCs. Besides constituting the first characterization, to our knowledge, of AS-ITV as a vaccination strategy, our data show that ITV strategies that lead to subtle differences in the persistence of parasites in the blood enable the characterization of the resulting immune responses, which will contribute to future research in vaccine design and malaria interventions.

Light-cured composite resins are widely used in dental restorations to fill cavities and fabricate temporary crowns. After curing, the residual monomer is a known to be cytotoxic, but increasing the curing time should improve biocompatibility. However, a biologically optimized cure time has not been determined through systematic experimentation. The objective of this study was to examine the behavior and function of human gingival fibroblasts cultured with flowable and bulk-fill composites cured for different periods of time, while considering the physical location of the cells with regard to the materials. Biological effects were separately evaluated for cells in direct contact with, and in close proximity to, the two composite materials. Curing time varied from the recommended 20 s to 40, 60, and 80 s. Pre-cured, milled-acrylic resin was used as a control. No cell survived and attached to or around the flowable composite, regardless of curing time. Some cells survived and attached close to (but not on) the bulk-fill composite, with survival increasing with a longer curing time, albeit to <20% of the numbers growing on milled acrylic even after 80 s of curing. A few cells (<5% of milled acrylic) survived and attached around the flowable composite after removal of the surface layer, but attachment was not cure-time dependent. Removing the surface layer increased cell survival and attachment around the bulk-fill composite after a 20-s cure, but survival was reduced after an 80-s cure. Dental-composite materials are lethal to contacting fibroblasts, regardless of curing time. However, longer curing times mitigated material cytotoxicity exclusively for bulk-fill composites when the cells were not in direct contact. Removing the surface layer slightly improved biocompatibility for cells in proximity to the materials, but not in proportion to cure time. In conclusion, mitigating the cytotoxicity of composite materials by increasing cure time is conditional on the physical location of cells, the type of material, and the finish of the surface layer. This study provides valuable information for clinical decision making and novel insights into the polymerization behavior of composite materials.

Since the discovery of bone healing around titanium chambers by Dr. Branemark in 1952, implants have advanced in technology, materials, and knowledge. Implants are fundamentally restored with one of two ways: screw or cement. The main advantages of screw-retained implant crowns are retrievability and application in minimal interocclusal spaces. However, the disadvantages of screwretained restorations are the effect of the access hole on esthetics and occlusion and difficulty in obtaining passive fit in multiple splinted units due to the lack of spatial relief (i.e., cement space). Cement-retained implant restorations

The sterile and long-lasting immunity against malaria can be induced by vaccination with genetically attenuated parasites (GAP). We have demonstrated that GAP-specific CD8+ T cells are key in protective immunity against pre-erythrocytic stages in mice. Here, we further characterized the CD8+ T cell phenotype and function associated with the longevity of the sterile protection induced by PyFabb/f- GAP. We demonstrated that vaccination of mice with Fabb/f- GAP resulted in a significant increase of effector/memory CD8+ T cells characterized as CD8bhi or CD8blo T cells expressing integrin CD49b primarily detected in the liver, a primary infection site. More importantly, CD49b+CD8blo T cell subset persisted for a long period and strongly associated with GAP-induced prolonged protection in Balb/c mice. In contrast, Fabb/f- GAP induced a short-lived CD49b+CD8bhi T cells but failed to induce a sustainable CD49b+CD8blo T cells leading to a short-term protection in C57Bl/6 mice. In understanding the biological effects of these CD8 T cell subsets, ex vivo functions and transcriptional analysis are underway. The predictive contributions of short-lived and long-lived CD8 T cells induced by GAP vaccination in protective efficacy against malaria would be highlighted by our findings.