A Bi-Mix Antibacterial Drug-Delivery System for Regenerative Endodontics

poster abstractTraumatic injuries to immature teeth have traditionally been managed via apexification therapy with intracanal calcium hydroxide/Ca(OH)2. Recently, the use of a bi-mix (metronidazole-MET and ciprofloxacin-CIP) paste appears to provide more predictable results. The objective of this study was to fabricate/characterize polydioxanone (PDSII®)-based electrospun bi-mix drug-delivery systems incorporated with the combination of MET and CIP. The antibacterial property of the released media was tested against Enterococcus faecalis (Ef), Porphyromonas gingivalis (Pg) , Aggregatibacter actinomycetemcomitans (Aa). PDSII® was dissolved in HFP to obtain a 10wt.% solution. Either MET, CIP or distinct drug combinations were added into the solution followed by homogenization overnight. Six groups of study were employed: Control-100%PDS, G1-100%MET, G2-75%MET+25%CIP, G3- 50%MET+50%CIP, G4-25%MET+75%CIP and G5-100%CIP. Electrospinning was done based on optimized parameters to fabricate the distinct samples. Uniaxial microtensile testing (n=10), Fourier transform infrared spectroscopy/FTIR, scanning electron microscopy (SEM), and agar diffusion assay were used to characterize mechanical, chemical and antibacterial properties. One-way ANOVA (only for fiber diameter), Kruskal-Wallis and Mann-Whitney tests were performed (α=0.05). The results showed that uniaxial tensile strength was not significantly decreased compared to the control except G3. Average fiber diameters were in the nano-scaled range and significantly lower then the control. SEM imaging indicated a submicron fibrous morphology. FTIR confirmed the characteristic peaks for PDS as well as for the employed drugs. Agar diffusion assay suggested that the higher the CIP concentration the greater the antibacterial property against Ef, Pg and Aa. The results indicated that higher amount of CIP (G4 & G5) did not compromise mechanical properties of nanofibers and showed the highest bacterial inhibition against Ef, Pg and Aa. Optimization of the physical-mechanical properties, kinetics of drug release, and the effect of released drugs on dental pulp stem cells are currently being pursued. Partially funded by American Association of Endodontists/AAE (M.C.B.)

Bimix antimicrobial scaffolds for regenerative endodontics

INTRODUCTION: Eliminating and/or inhibiting bacterial growth within the root canal system has been shown to play a key role in the regenerative outcome. The aim of this study was to synthesize and determine in vitro both the antimicrobial effectiveness and cytocompatibility of bimix antibiotic-containing polydioxanone-based polymer scaffolds. METHODS: Antibiotic-containing (metronidazole [MET] and ciprofloxacin [CIP]) polymer solutions (distinct antibiotic weight ratios) were spun into fibers as a potential mimic to the double antibiotic paste (DAP, a MET/CIP mixture). Fiber morphology, chemical characteristics, and tensile strength were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy, and tensile testing, respectively. Antimicrobial efficacy was tested over time (aliquot collection) against Enterococcus faecalis (Ef), Porphyromonas gingivalis (Pg), and Fusobacterium nucleatum (Fn). Similarly, cytotoxicity was evaluated in human dental pulp stem cells. Data were statistically analyzed (P < .05). RESULTS: Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed that electrospinning was able to produce antibiotic-containing fibers with a diameter mostly in the nanoscale. The tensile strength of 1:1MET/CIP scaffolds was significantly (P < .05) higher than pure polydioxanone (control). Meanwhile, all other groups presented similar strength as the control. Aliquots obtained from antibiotic-containing scaffolds inhibited the growth of Ef, Pg, and Fn, except pure MET, which did not show an inhibitory action toward Pg or Fn. Antibiotic-containing aliquots promoted slight human dental pulp stem cell viability reduction, but none of them were considered to be cytotoxic. CONCLUSIONS: Our data suggest that the incorporation of multiple antibiotics within a nanofibrous scaffold holds great potential toward the development of a drug delivery system for regenerative endodontics

1H NMR-Linked Metabolomics Analysis of Liver from a Mouse Model of NP-C1 Disease

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link

Tumor cell–organized fibronectin maintenance of a dormant breast cancer population

Tumors can undergo long periods of dormancy, with cancer cells entering a largely quiescent, nonproliferative state before reactivation and outgrowth. To understand the role of the extracellular matrix (ECM) in regulating tumor dormancy, we created an in vitro cell culture system with carefully controlled ECM substrates to observe entrance into and exit from dormancy with live imaging. We saw that cell populations capable of surviving entrance into long-term dormancy were heterogeneous, containing quiescent, cell cycle–arrested, and actively proliferating cells. Cell populations capable of entering dormancy formed an organized, fibrillar fibronectin matrix via αvβ3 and α5β1 integrin adhesion, ROCK-generated tension, and TGFβ2 stimulation, and cancer cell outgrowth after dormancy required MMP-2–mediated fibronectin degradation. We propose this approach as a useful, in vitro method to study factors important in regulating dormancy, and we used it here to elucidate a role for fibronectin deposition and MMP activation

Tumor cell-organized fibronectin is required to maintain a dormant breast cancer population [preprint]

Tumors can undergo long periods of dormancy, with cancer cells entering a largely quiescent, non-proliferative state before reactivation and outgrowth. For a patient, these post-remission tumors are often drug resistant and highly aggressive, resulting in poor prognosis. To understand the role of the extracellular matrix (ECM) in regulating tumor dormancy, we created an in vitro cell culture system that combines carefully controlled ECM substrates with nutrient deprivation to observe entrance into and exit from dormancy with live imaging. We saw that cell populations capable of surviving entrance into long-term dormancy were heterogeneous, containing quiescent, cell cycle arrested, and actively proliferating cells. Cell populations that endured extended periods of serum-deprivation-induced dormancy formed an organized, fibrillar fibronectin matrix via αvβ3 and α5β1 integrin adhesion, ROCK-generated tension, and TGFβ2 stimulation. We surmised that the fibronectin matrix was primarily a mediator of cell survival, not proliferation, during the serum-deprivation stress, bacause cancer cell outgrowth after dormancy required MMP-2-mediated fibronectin degradation. Given the difficulty of animal models in observing entrance and exit from dormancy in real-time, we propose this approach as a new, in vitro method to study factors important in regulating dormancy, and we used it here to elucidate a role for fibronectin deposition and MMP activation

Acetyl-leucine slows disease progression in lysosomal storage disorders

Acetyl-DL-leucine is a derivative of the branched chain amino acid leucine. In observational clinical studies acetyl-DL-leucine improved symptoms of ataxia, in particular in patients with the lysosomal storage disorder, Niemann-Pick disease type C1. Here, we investigated acetyl-DL-leucine and its enantiomers acetyl-L-leucine and acetyl-D-leucine in symptomatic Npc1-/- mice and observed improvement in ataxia with both individual enantiomers and acetyl-DL-leucine. When acetyl-DL-leucine and acetyl-L-leucine were administered pre-symptomatically to Npc1-/- mice, both treatments delayed disease progression and extended life span, whereas acetyl-D-leucine did not. These data are consistent with acetyl-L-leucine being the neuroprotective enantiomer. Altered glucose and antioxidant metabolism were implicated as one of the potential mechanisms of action of the L enantiomer in Npc1-/- mice. When the standard of care drug miglustat and acetyl-DL-leucine were used in combination significant synergy resulted. In agreement with these pre-clinical data, when Niemann-Pick disease type C1 patients were evaluated after 12 months of acetyl-DL-leucine treatment, rates of disease progression were slowed, with stabilisation or improvement in multiple neurological domains. A beneficial effect of acetyl-DL-leucine on gait was also observed in this study in a mouse model of GM2 gangliosidosis (Sandhoff disease) and in Tay-Sachs and Sandhoff disease patients in individual cases of off-label-use. Taken together, we have identified an unanticipated neuroprotective effect of acetyl-L-leucine and underlying mechanisms of action in lysosomal storage diseases, supporting its further evaluation in clinical trials in lysosomal disorders

Sociality predicts individual variation in the immunity of free-ranging rhesus macaques

This work was supported by CONICYT-Chilean scholarship [number 72190290], NIH grant [number R01AG060931] to N.S-M., L.J.N.B. and J.P.H., NIH grant [number R00AG051764] to N.S-M., NIH grant [number MH118203] to L.J.N.B.. and M.L.P, and NSF grant [number 1800558] to J.P.H. and Susan Anton. The CPRC is supported by the National Institutes of Health. An Animal and Biological Material Resource Center Grant [P40OD012217] was awarded to UPR from the Office of Research Infrastructure Programs (ORIP), and a Research Facilities Construction Grant [C06OD026690] was awarded for the renovation of CPRC facilities after Hurricane Maria.Social integration and social status can substantially affect an individual's health and survival. One route through which this occurs is by altering immune function, which can be highly sensitive to changes in the social environment. However, we currently have limited understanding of how sociality influences markers of immunity in naturalistic populations where social dynamics can be fully realized. To address this gap, we asked if social integration and social status in free-ranging rhesus macaques (Macaca mulatta) predict anatomical and physiological markers of immunity. We used data on agonistic interactions to determine social status, and social network analysis of grooming interactions to generate measures of individual variation in social integration. As measures of immunity, we included the size of two of the major organs involved in the immune response, the spleen and liver, and counts of three types of blood cells (red blood cells, platelets, and white blood cells). Controlling for body mass and age, we found that neither social status nor social integration predicted the size of anatomical markers of immunity. However, individuals that were more socially connected, i.e., with more grooming partners, had lower numbers of white blood cells than their socially isolated counterparts, indicating lower levels of inflammation with increasing levels of integration. These results build upon and extend our knowledge of the relationship between sociality and the immune system in humans and captive animals to free-ranging primates, demonstrating generalizability of the beneficial role of social integration on health.Publisher PDFPeer reviewe

Trade-offs between sociality and gastrointestinal parasite infection in the context of a natural disaster

This work was supported by ANID-Chilean scholarship [number 72190290], the National Institutes of Health Grants [R01AG060931] to N.S-M., L.J.N.B. and J.P.H., [R00AG051764] to N.S-M, [R01MH118203] to M.L.P., M.J.M, L.J.N.B. and N.S-M., [R01MH096875] to M.L.P., L.J.N.B. and M.J.M., [U01MH121260] to N.S-M., M.L.P. and M.J.M., a European Research Council Consolidator Grant to L.J.N.B. [Friend Origins - 864461].Parasites and infectious diseases constitute important challenges particularly for group-living animals. Social contact and shared space can both increase parasite transmission risk, while individual differences in social capital can help prevent infections. For example, high social status individuals and those with more or stronger affiliative partnerships may have better immunity and, thus, lower parasitic burden. To test for health trade-offs in the costs and benefits of sociality, we quantified how parasitic load varied with an individual's social status, as well as with their affiliative relationships with weakly and strongly bonded partners, in a free-ranging population of rhesus macaques, Macaca mulatta. We found that high status was associated with a lower risk of protozoa infection at older ages compared to younger and low-status animals. Social resources can also be protective against infection under environmentally challenging situations, such as natural disasters. Using cross-sectional data, we additionally examined the impact of a major hurricane on the sociality - parasite relationship in this system and found that the hurricane influenced the prevalence of specific parasites independent of sociality. Overall, our study adds to the growing evidence for social status as a strong predictor of infection risk and highlights how extreme environmental events could shape vulnerability and resistance to infection.Peer reviewe