Quantification of the Burst Phase during Non-Nutritive Suck Production in Preterm Infants

Premature birth places infants at increased risk for learning disabilities, delayed development of speech, language and motor skills, and mortality. The premature infant often has difficulties with respiration and feeding and therefore may remain in the hospital for prolonged periods of time. The non-nutritive suck (NNS) is a motor behavior which can be observed and used to make inference about brain development and organization in this young population. The purpose of this study was to quantify the frequency modulation of the NNS burst in two groups of preterm infants, including those with and those without respiratory distress syndrome (RDS). Thirty-two (32) preterm infants were consented and distributed into one of the following groups: Control (N=17) and RDS (N=15). Digitized samples of NNS compression pressure waveforms were collected 15 minutes prior to scheduled feedings on a weekly basis. Quadratic regression analysis revealed that healthy preterm infants produced longer NNS bursts and the mean burst initiation cycle periods were shorter when compared to the RDS group. Moreover, NNS burst initiation shows a prominent frequency modulated (FM) segment upon initiation which appears to be a significant feature of the suck central pattern generator (sCPG) and is markedly different for RDS preterm infants as compared to their healthy preterm counterparts. Identification of such characteristics provides specific criteria and description of the NNS CPG which may offer a new diagnostic criterion which can be used to gauge the developmental status of oromotor control systems among these fragile infants

A role for cell sex in stem cell-mediated skeletal muscle regeneration: Female cells have higher muscle regeneration efficiency

We have shown that muscle-derived stem cells (MDSCs) transplanted into dystrophic (mdx) mice efficiently regenerate skeletal muscle. However, MDSC populations exhibit heterogeneity in marker profiles and variability in regeneration abilities. We show here that cell sex is a variable that considerably influences MDSCs' regeneration abilities. We found that the female MDSCs (F-MDSCs) regenerated skeletal muscle more efficiently. Despite using additional isolation techniques and cell cloning, we could not obtain a male subfraction with a regeneration capacity similar to that of their female counterparts. Rather than being directly hormonal or caused by host immune response, this difference in MDSCs' regeneration potential may arise from innate sex-related differences in the cells' stress responses. In comparison with F-MDSCs, male MDSCs have increased differentiation after exposure to oxidative stress induced by hydrogen peroxide, which may lead to in vivo donor cell depletion, and a proliferative advantage for F-MDSCs that eventually increases muscle regeneration. These findings should persuade researchers to report cell sex, which is a largely unexplored variable, and consider the implications of relying on cells of one sex. © The Rockefeller University Press

The Role of Bax and Bak in Modulating the Interferon Response in HPV-31 infected cells

High risk Human papillomaviruses (HPV) are the causative agents of several human cancers, including cervical cancers and oropharyngeal cancers. HPV-31 is a high-risk oncogenic alpha HPV that infects mucosal epithelial cells. Bax and Bak are pro-apoptotic proteins that induce mitochondrial outer membrane permeabilization (MOMP), leading to the activation of caspases, which are cysteine proteases that can induce apoptotic cell death. HPV-31 induces low level activation of caspases-9, -3, and -7 upon epithelial differentiation, suggesting that MOMP is triggered during the productive phase of the HPV-31 life cycle. We have published that apoptotic caspase activity is required to suppress an IFN responses during HPV productive replication. This project is focused on determining if this caspase activation is occurring through Bax/Bak-induced MOMP using siRNA in HPV-31 infected cervical epithelial cells (CIN612-9E) with or without the presence of a pan caspase inhibitor, and if Bax/Bak are important for HPV’s ability to block an IFN response. Our findings show Bax and Bak activation are required for activation of Caspase 7, and that Bax/Bak knockdown does not block the IFN response under caspase-deficient conditions. We found Bax and Bak are required for productive replication of HPV-31 and that activation of JNK occurs in a Bax/Bak-dependent manner. Our study demonstrates that Bax and Bak are necessary for Caspase activation in HPV infected keratinocytes but do not affect the IFN response.Bachelor of Scienc

Inflammation and Stem Cell Transplantation

Myoblast transplantation has been investigated as a treatment for Duchenne Muscular Dystrophy and injured myocardial tissue. Multiple groups have isolated an early myogenic precursor population, termed muscle-derived stem cells (MDSCs) that have a superior ability to regenerate dystrophin-positive myofibers and improve cardiac function following an ischemic event as compared to more differentiated myoblasts. The initial local environment of these transplantations involves a high degree of inflammation and its associated major component, oxidative stress. Here, we report that a resistance to these stresses is an important factor determining the regenerative capacity of muscle stem cells in skeletal and cardiac muscle. MDSCs have an increased antioxidant capacity that protects them from intracellular oxidative damage while myoblasts have lower levels of survival and delayed differentiation following exposure to oxidative stress. These experiments were conducted using a series of high throughput assays that combine robotic live-cell microscopy with custom image analysis software. Further, when antioxidant levels in MDSCs are lowered to values comparable to myoblasts, the regenerative capacity of MDSCs decreases to levels comparable to myoblasts in both skeletal muscle and cardiac cell therapies. These findings indicate the important role inflammation plays in cell therapies, and identifies an important new mechanism by which stem cells display a unique regenerative capacity and also a new phenotype in selecting cell populations with enhanced regeneration capacity

Borehole water level response to barometric pressure as an indicator of aquifer vulnerability

The response of borehole water levels to barometric pressure changes in semiconfined aquifers can be used to determine barometric response functions from which aquifer and confining layer properties can be obtained. Following earlier work on barometric response functions and aquifer confinement, we explore the barometric response function as a tool to improve the assessment of groundwater vulnerability in semiconfined aquifers, illustrated through records from two contrasting boreholes in the semiconfined Chalk Aquifer, East Yorkshire, UK. After removal of recharge and Earth tide influences on the water level signal, barometric response functions were estimated and aquifer and confining layer properties determined through an analytical model of borehole water level response to barometric pressure. A link between the thickness and vertical diffusivity of the confining layer determined from the barometric response function, and groundwater vulnerability is proposed. The amplitude spectrum for barometric pressure and instrument resolution favor determination of the barometric response function at frequencies to which confining layer diffusivities are most sensitive. Numerical modeling indicates that while the high frequency response reflects confining layer properties in the immediate vicinity of the borehole, the low frequency response reflects vertical, high diffusivity pathways though the confining layer some hundreds of meters distant. A characteristic time scale parameter, based on vertical diffusivities and thicknesses of the saturated and unsaturated confining layer, is introduced as a measure of semiconfined aquifer vulnerability. The study demonstrates that the barometric response function has potential as a tool for quantitative aquifer vulnerability assessment in semiconfined aquifers

The Role of Antioxidation and Immunomodulation in Postnatal Multipotent Stem Cell-Mediated Cardiac Repair

Oxidative stress and inflammation play major roles in the pathogenesis of coronary heart disease including myocardial infarction (MI). The pathological progression following MI is very complex and involves a number of cell populations including cells localized within the heart, as well as cells recruited from the circulation and other tissues that participate in inflammatory and reparative processes. These cells, with their secretory factors, have pleiotropic effects that depend on the stage of inflammation and regeneration. Excessive inflammation leads to enlargement of the infarction site, pathological remodeling and eventually, heart dysfunction. Stem cell therapy represents a unique and innovative approach to ameliorate oxidative stress and inflammation caused by ischemic heart disease. Consequently, it is crucial to understand the crosstalk between stem cells and other cells involved in post-MI cardiac tissue repair, especially immune cells, in order to harness the beneficial effects of the immune response following MI and further improve stem cell-mediated cardiac regeneration. This paper reviews the recent findings on the role of antioxidation and immunomodulation in postnatal multipotent stem cell-mediated cardiac repair following ischemic heart disease, particularly acute MI and focuses specifically on mesenchymal, muscle and blood-vessel-derived stem cells due to their antioxidant and immunomodulatory properties

Platelet-Rich Plasma Promotes the Proliferation of Human Muscle Derived Progenitor Cells and Maintains Their Stemness

Human muscle-derived progenitor cells (hMDPCs) offer great promise for muscle cell-based regenerative medicine; however, prolonged ex-vivo expansion using animal sera is necessary to acquire sufficient cells for transplantation. Due to the risks associated with the use of animal sera, the development of a strategy for the ex vivo expansion of hMDPCs is required. The purpose of this study was to investigate the efficacy of using platelet-rich plasma (PRP) for the ex-vivo expansion of hMDPCs. Pre-plated MDPCs, myoendothelial cells, and pericytes are three populations of hMDPCs that we isolated by the modified pre-plate technique and Fluorescence Activated Cell Sorting (FACS), respectively. Pooled allogeneic human PRP was obtained from a local blood bank, and the effect that thrombin-activated PRP-releasate supplemented media had on the ex-vivo expansion of the hMDPCs was tested against FBS supplemented media, both in vitro and in vivo. PRP significantly enhanced short and long-term cell proliferation, with or without FBS supplementation. Antibody-neutralization of PDGF significantly blocked the mitogenic/proliferative effects that PRP had on the hMDPCs. A more stable and sustained expression of markers associated with stemness, and a decreased expression of lineage specific markers was observed in the PRP-expanded cells when compared with the FBS-expanded cells. The in vitro osteogenic, chondrogenic, and myogenic differentiation capacities of the hMDPCs were not altered when expanded in media supplemented with PRP. All populations of hMDPCs that were expanded in PRP supplemented media retained their ability to regenerate myofibers in vivo. Our data demonstrated that PRP promoted the proliferation and maintained the multi-differentiation capacities of the hMDPCs during ex-vivo expansion by maintaining the cells in an undifferentiated state. Moreover, PDGF appears to be a key contributing factor to the beneficial effect that PRP has on the proliferation of hMDPCs. © 2013 Li et al

Hydrogen Peroxide, Povidone-Iodine and Chlorhexidine Fail to Eradicate Staphylococcus aureus Biofilm from Infected Implant Materials

Hydrogen peroxide, povidone-iodine, and chlorhexidine are antiseptics that are commonly added to irrigants to either prevent or treat infection. There are little clinical data available that demonstrate efficacy of adding antiseptics to irrigants in the treatment of periprosthetic joint infection after biofilm establishment. The objective of the study was to assess the bactericidal activity of the antiseptics on S. aureus planktonic and biofilm. For planktonic irrigation, S. aureus was exposed to different concentrations of antiseptics. S. aureus biofilm was developed by submerging a Kirschner wire into normalized bacteria and allowing it to grow for forty-eight hours. The Kirschner wire was then treated with irrigation solutions and plated for CFU analysis. Hydrogen peroxide, povidone-iodine, and chlorhexidine were bactericidal against planktonic bacteria with over a 3 log reduction (p < 0.0001). Unlike cefazolin, the antiseptics were not bactericidal (less than 3 log reduction) against biofilm bacteria but did have a statistical reduction in biofilm as compared to the initial time point (p < 0.0001). As compared to cefazolin treatment alone, the addition of hydrogen peroxide or povidone-iodine to cefazolin treatment only additionally reduced the biofilm burden by less than 1 log. The antiseptics demonstrated bactericidal properties with planktonic S. aureus; however, when used to irrigate S. aureus biofilms, these antiseptics were unable to decrease biofilm mass below a 3 log reduction, suggesting that S. aureus biofilm has a tolerance to antiseptics. This information should be considered when considering antibiotic tolerance in established S. aureus biofilm treatment