Effect of endodontic retreatment on the bond strength of resin cements to root canal dentin.

PURPOSE: To evaluate the effect of endodontic retreatment on the bond strength of different cementation techniques (self-adhesive and conventional resin cement) through the push-out mechanical testing and the penetrability of resin cements to root dentin. METHODS: 60 human teeth with single oval-shaped canals were used (n=15) : G1 - Endodontic treatment and cementation with RelyX ARC (ETA); G2 - Endodontic treatment and cementation with U200 (ETU); G3 - Endodontic retreatment and cementation with RelyX ARC (ERA); G4 - Endodontic retreatment and cementation with U200 (ERU). The groups with conventional endodontic treatment were filled with AH plus (ETA and ETU), while the groups that were submitted to endodontic retreatment were initially filled with Endofill and afterwards with AH Plus. Each radicular third (cervical, middle, and apical, of each tooth) was submitted to push-out bond strength testing, followed by evaluation with confocal laser microscopy to determine the penetration of the resin cements, and scanning electron microscopy was used to evaluate the failure mode. The parametric data were evaluated by two-way ANOVA and Tukey tests, and non-parametric data by Kruskal-Wallis and Dunn tests (α< 0.05). RESULTS: The ETA group had higher bond strength values to intra-radicular dentin than the other groups in all root thirds (P< 0.05). Endodontic retreatment had a negative impact on the penetration and push-out bond strength of RelyX ARC and U200 cement, regardless of the analyzed radicular third. CLINICAL SIGNIFICANCE: The bond strength between fiber post and root dentin can be affected by several factors, such as technical failure, cementation technique, pretreatment of the dentin, type of post and adaptation. The endodontic retreatment interferes negatively on the bond strength and penetrability of RelyX ARC and U200 cements to dentin, regardless of the analyzed radicular third. Therefore, the endodontic retreatment might have an adverse effect due to over preparation and aggression to the root canal.

Islet-Derived CD4 T Cells Targeting Proinsulin in Human Autoimmune Diabetes.

Type 1 diabetes results from chronic autoimmune destruction of insulin-producing ß-cells within pancreatic islets. Although insulin is a critical self-antigen in animal models of autoimmune diabetes, due to extremely limited access to pancreas samples, little is known about human antigenic targets for islet-infiltrating T cells. Here we show that proinsulin peptides are targeted by islet-infiltrating T cells from patients with type 1 diabetes. We identified hundreds of T cells from inflamed pancreatic islets of three young organ donors with type 1 diabetes with a short disease duration with high-risk HLA genes using a direct T-cell receptor (TCR) sequencing approach without long-term cell culture. Among 85 selected CD4 TCRs tested for reactivity to preproinsulin peptides presented by diabetes-susceptible HLA-DQ and HLA-DR molecules, one T cell recognized C-peptide amino acids 19-35, and two clones from separate donors responded to insulin B-chain amino acids 9-23 (B:9-23), which are known to be a critical self-antigen-driving disease progress in animal models of autoimmune diabetes. These B:9-23-specific T cells from islets responded to whole proinsulin and islets, whereas previously identified B:9-23 responsive clones from peripheral blood did not, highlighting the importance of proinsulin-specific T cells in the islet microenvironment.

Effects of different complementary feeding regimens on iron status and enteric microbiota in breastfed infants.

OBJECTIVE: To compare iron status in breastfed infants randomized to groups receiving complementary feeding regimens that provided iron from fortified infant cereals or meats, and to examine the development of the enteric microbiota in these groups. STUDY DESIGN: Forty-five exclusively breastfed 5-month-old infants were randomized to 1 of 3 feeding groups (FGs)-commercially available pureed meats, iron- and zinc-fortified infant cereals, or iron-only fortified infant cereals-as the first and primary complementary food through 9-10 months of age. Dietary iron was determined by monthly 3-day diet records. Iron status was assessed at the end of the study by measurements of hemoglobin, serum ferritin, and soluble transferrin receptor levels. In a subsample of 14 infants, enteric microbiota were profiled in monthly stool samples (5-9 months) by 16S ribosomal RNA gene pyrosequencing. RESULTS: Infants in the 2 cereal FGs had 2- to 3-fold greater daily iron intakes versus the meat FG (P < .0001). More than one-quarter (27%) of the infants had a low serum ferritin level, and 36% were mildly anemic, with no significant differences by FG; more infants in the meat FG had a high soluble transferrin receptor value (P = .03). Sequence analysis identified differences by time and FG in the abundances of several bacterial groups, including significantly more abundant butyrate-producing Clostridium group XIVa in the meat FG (P = .01) CONCLUSION: A high percentage of healthy infants who were breastfed-only were iron-deficient, and complementary feeding, including iron exposure, influenced the development of the enteric microbiota. If these findings are confirmed, then reconsideration of strategies to both meet infants' iron requirements and optimize the developing microbiome may be warranted.

Visualization of F-actin localization and dynamics with live cell markers in Neurospora crassa.

Filamentous actin (F-actin) plays essential roles in filamentous fungi, as in all other eukaryotes, in a wide variety of cellular processes including cell growth, intracellular motility, and cytokinesis. We visualized F-actin organization and dynamics in living Neurospora crassa cells via confocal microscopy of growing hyphae expressing GFP fusions with homologues of the actin-binding proteins fimbrin (FIM) and tropomyosin (TPM-1), a subunit of the Arp2/3 complex (ARP-3) and a recently developed live cell F-actin marker, Lifeact (ABP140 of Saccharomyces cerevisiae). FIM-GFP, ARP-3-GFP, and Lifeact-GFP associated with small patches in the cortical cytoplasm that were concentrated in a subapical ring, which appeared similar for all three markers but was broadest in hyphae expressing Lifeact-GFP. These cortical patches were short-lived, and a subset was mobile throughout the hypha, exhibiting both anterograde and retrograde motility. TPM-1-GFP and Lifeact-GFP co-localized within the Spitzenkörper (Spk) core at the hyphal apex, and were also observed in actin cables throughout the hypha. All GFP fusion proteins studied were also transiently localized at septa: Lifeact-GFP first appeared as a broad ring during early stages of contractile ring formation and later coalesced into a sharper ring, TPM-1-GFP was observed in maturing septa, and FIM-GFP/ARP3-GFP-labeled cortical patches formed a double ring flanking the septa. Our observations suggest that each of the N. crassa F-actin-binding proteins analyzed associates with a different subset of F-actin structures, presumably reflecting distinct roles in F-actin organization and dynamics. Moreover, Lifeact-GFP marked the broadest spectrum of F-actin structures; it may serve as a global live cell marker for F-actin in filamentous fungi.