Feasibility and Effect of Cervical Resistance Training on Head Kinematics in Youth Athletes: A Pilot Study.

Greater neck girth and strength may be associated with a lower risk of sport-related concussion due to mitigation of head accelerations by the neck. However, neck strengthening exercise remains unstudied in youth athletes. Therefore, this pilot study assessed the feasibility and effect of targeted neck strengthening exercises in youth athletes. Seventeen participants were allocated to perform 8-wk manual resistance-based neck strengthening (n = 13) or control resistance exercise (n = 4) programs. Before and after the intervention, participants completed laboratory-based assessments of neck size, strength, and head kinematics during standardized test loading in each plane of motion. Descriptive statistics were calculated to compare pre-post changes between the two groups. All participants safely and successfully completed the intervention. Neck girth and strength increased in both groups, with greater increases in the neck strengthening group. Across all planes of motion, overall changes in head linear and angular velocity decreased in both groups, with greater decreases in ΔV in the neck strengthening group and greater decreases in Δω in controls. These results suggest the potential for resistance exercise training to reduce youth athletes' risk for sport-related concussion by increasing neck girth and strength. Additional research is needed to determine optimal neck strengthening programs.

Preclinical methods for the evaluation of periodontal regeneration in vivo.

For the determination of key factors or devices that promote periodontal regeneration, preclinical investigations using in vivo animal models are critical for evaluating the biological responses before human clinical trial testing. In this chapter, we provide an overview on the commonly used preclinical animals for the study of reconstructive procedures to promote bone and soft tissue repair of tooth-supporting periodontal defects. Steps are provided on the animal management for evaluation of outcome measures using descriptive histology, histomorphometry, three-dimensional imaging, and safety assessments. The use of these key measures of periodontal regeneration should aid investigators in the selection of appropriate surrogate endpoints to be utilized in the clinical arena, which are not practical or ethical in humans. These methods will prepare investigators and assist them in identifying endpoints that can then be adapted to human clinical trial planning.

LMP1 regulates periodontal ligament progenitor cell proliferation and differentiation.

LMP1 is an intracellular scaffold protein that contains a PDZ domain and three LIM domains. LMP1 has multiple functions including regulating mesenchymal stem cell (MSC) osteogenesis. Gene delivery of LMP1 induces bone formation in vivo in heterotopic and orthotopic sites. However, little is known about the physiological function and gene regulatory mechanisms of LMP1 in MSCs at the molecular level. Periodontal ligament (PDL) cells are a unique progenitor cell population that can differentiate into multiple cell types, including osteoblasts, adipocytes, or chondrocytes. This study sought to determine the physiological function and gene regulatory mechanisms of LMP1 in PDL cells at the molecular level. We show that LMP1 is upregulated in early stage of PDL cell osteogenic differentiation. Stable gene knockdown of LMP1 by shRNA inhibits DNA synthesis and corresponding cell proliferation in PDL cells, and further leads to decreased mineralization in vitro. Overexpression of LMP1 increases cell proliferation, and PDZ and ww-interacting domains are not sufficient to mediate this effect. Further, we found that in PDL cells, LMP1 is a downstream target gene of TGF-beta1 that is an early signal critical in preosteoblast proliferation and differentiation. TGF-beta1 stimulates PDL cell proliferation, however, this effect is compromised when LMP1 is knocked down. We further identified that the activation of TAK1-JNK/p38 kinase cascade is involved in the LMP1 gene regulation by TGF-beta1. We conclude that LMP1 is a downstream gene of TGF-beta1, involved in PDL cell proliferation. Our findings advance the understanding of the physiological function of LMP1 and define a regulatory mechanism of LMP1 in PDL progenitor cells and other MSCs.

Pro-inflammatory biomarkers during experimental gingivitis in patients with type 1 diabetes mellitus: a proof-of-concept study.

AIM: To compare gingival crevicular fluid (GCF) biomarker levels and microbial distribution in plaque biofilm (SP) samples for subjects with type 1 diabetes (T1DM) versus healthy subjects without diabetes during experimental gingivitis (EG). MATERIALS AND METHODS: A total of nine T1DM patients and nine healthy controls of age and gender similar to the T1DM patients were monitored for 35 days during EG. Hygiene practices were stopped for 3 weeks, and GCF, SP, plaque index (PI) and gingival index were determined. IL-1beta, IL-8, MMP-8 and MMP-9 were quantified by enzyme-linked immunosorbent assay, and SP samples were assessed by DNA-DNA hybridization for a panel of 40 subgingival microbial species. RESULTS: IL-1beta levels in T1DM patients were elevated compared with healthy individuals, and showed differences between groups at 7-21 days while healthy patients showed IL-1beta increases from baseline to 14-21 days (p<0.05). Differences were observed in MMP-9 levels between patients with and without T1DM at 7-14 days (p<0.05). Orange complex species and PI measurements displayed a superior correlation with biomarker levels when compared with other complexes or clinical measurements during EG. CONCLUSIONS: The mean GCF biomarker levels for IL-1beta and MMP-8 were most significantly elevated in T1DM subjects compared with healthy individuals during EG, not resulting from differences in the mean PI or microbial composition.