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Synthesis and Cell Adhesive Properties of Linear and Cyclic RGD Functionalized Polynorbornene Thin Films

Described herein is the efficient synthesis and evaluation of bioactive arginine-glycine-aspartic acid (RGD) functionalized polynorbornene-based materials for cell adhesion and spreading. Polynorbornenes containing either linear or cyclic RGD peptides were synthesized by ring-opening metathesis polymerization (ROMP) using the well-defined ruthenium initiator [(H_(2)IMes)(pyr)_(2)(Cl)_(2)Ru═CHPh]. The random copolymerization of three separate norbornene monomers allowed for the incorporation of water-soluble polyethylene glycol (PEG) moieties, RGD cell recognition motifs, and primary amines for postpolymerization cross-linking. Following polymer synthesis, thin-film hydrogels were formed by cross-linking with bis(sulfosuccinimidyl) suberate (BS^3), and the ability of these materials to support human umbilical vein endothelial cell (HUVEC) adhesion and spreading was evaluated and quantified. When compared to control polymers containing either no peptide or a scrambled RDG peptide, polymers with linear or cyclic RGD at varying concentrations displayed excellent cell adhesive properties in both serum-supplemented and serum-free media. Polymers with cyclic RGD side chains maintained cell adhesion and exhibited comparable integrin binding at a 100-fold lower concentration than those carrying linear RGD peptides. The precise control of monomer incorporation enabled by ROMP allows for quantification of the impact of RGD structure and concentration on cell adhesion and spreading. The results presented here will serve to guide future efforts for the design of RGD functionalized materials with applications in surgery, tissue engineering, and regenerative medicine

The Long Duration Exposure Facility (LDEF) photographic survey special publication

During the construction, integration, launch, retrieval and deintegration of the Long Duration Exposure Facility (LDEF), photographic surveys were made. Approximately 10,000 photographs were taken during the various phases of the LDEF project. These surveys are of technical and scientific importance because they revealed the pre and post flight conditions of the experiment trays as well as the spacecraft. Visual inspection of the photographs reveal valuable data such as space environment's effects and the earth atmosphere's effects post-retrieval. Careful files and records have been kept of these photographs. Each photograph has a Kennedy Space Center photo number or a Johnson Spaceflight Center photo number as well as a Langley Research Center photo number. The tray number, row number, and experiment number are also noted. Out of the 10,000 photographs taken, approximately 700 selected photographs were chosen for publication in a NASA Special Publication (SP) because they reveal the effects of space exposure to the viewer. These photographs will give researchers and spacecraft designers visual images of the effects of the space environment on specific materials, systems and spacecraft in general. One can visually see the degradation of thermal blankets, meteoroid craters, outgassing discoloration, atomic oxygen erosion, etc

Photographic Survey of the LDEF Mission

This publication documents a selected number of pre-flight, in-flight, and postflight photographs of the LDEF and experiments. Changes in condition of the experiments caused by space exposure are discussed. Accompanying this black and white publication it a CD-ROM that contains the color version of the photographs as well as the text

Vascularization of the human intervertebral disc: A scoping review

Intervertebral discs (IVDs) are often referred to as the largest avascular structures of the human body, yet a collective resource characterizing the vascularization of the IVD does not exist. To address this gap, the objective of this study was to conduct a comprehensive search of the literature to review and summarize current knowledge of the prevalence and localization of blood supply in human IVDs, with a scoping review. A comprehensive search of peer-reviewed publications on the topic of IVD vascularization in humans was conducted across six electronic databases: PubMed, EMBASE, MEDLINE, Scopus, Web of Science, and BIOSIS Previews. Studies of humans were included regardless of age, sex, ethnicity, and health status, with the exception of IVD herniation. Two independent reviewers screened titles and abstracts and full-texts according to eligibility criteria. The review was conducted and reported according to Preferred Reporting Items for Systematic Reviews Extension for Scoping Reviews guidelines. Our search yielded 3122 articles, with 22 articles meeting the inclusion criteria. The study samples ranged in age from fetal to \u3e90 years and included both sexes, various health statuses, and used different methodologies (eg, histology, medical imaging, and gross dissection) to assess vasculature. Overall, consistent observations were that (a) the nucleus pulposus of the IVD is avascular throughout life, (b) both the cartilage endplates and annulus fibrosus receive considerable blood supply early in life that diminishes over the lifespan, and (c) vascular ingrowth into the cartilage endplates and inner layers of the annulus fibrosus is commonly associated with damaged or disrupted tissue, irrespective of age. Histology and immunohistochemistry are often used to report vascularization of the IVD. The body of the current literature suggests that the IVD should not be generalized as an avascular tissue. Instead, vascularization of the IVD differs based on the constituent tissues, their age, and state of degeneration or damage

Restoration of Frequency-Dependent Depression of the H-Reflex by Passive Exercise in Spinal Rats

Hyper-reflexia, measured as a decrease of low frequency-dependent depression of the H-reflex, is known to occur in both humans and animals after spinal cord injury (SCI). Previous studies have shown that passive exercise for 3 months could be used to restore low frequency-dependent depression of the H-reflex after SCI. To determine the effects of various periods of time on the ability of passive exercise to restore low frequency-dependent depression of the H-reflex. Spinal Cord Injury Mobilization Program of the Center for Translational Neuroscience, the research arm of the Jackson T Stephens Spine and Neuroscience Institute, Little Rock, AR, USA. Adult rats underwent complete spinal cord transection at the T10 level. The hindlimbs were passively exercised in different groups of rats for 1 h/day, 5 days/week for 15, 30, 45, 60, or 90 days, and low frequency-dependent depression of the H-reflex was tested. Statistically significant low frequency-dependent depression of the H-reflex was evident by 30 days of exercise, although numerical reductions were seen even at 15 days. There was a linear decrease in low frequency-dependent depression of the H-reflex with duration of passive exercise. Passive exercise can restore frequency-dependent depression of spinal reflexes in a time-dependent manner if used following complete spinal transection

Epidemiology of pediatric injury in Malawi: Burden of disease and implications for prevention

AbstractPurposePediatric injuries pose a significant health burden in sub-Saharan Africa, though historic data are too scarce to appreciate the extent of the problem. The purpose of this study is to utilize a comprehensive database to describe the epidemiology of pediatric injuries at a tertiary hospital in Malawi.MethodsData were prospectively collected on patients presenting to the emergency department for treatment of injuries from 2008 to 2010 (n = 23,625). The subset of pediatric patients (n = 7233) underwent cross-sectional analysis to examine demographics, injury environment, timing and mechanisms.ResultsPediatric patients, (0–16 years) comprised 30.6% of all trauma patients. Mean age was 7.2 years. Falls were the most common injury (43%), followed by burns (11.1%), pedestrian road traffic injuries (9.7%), foreign bodies (7.5%), and assaults (7.2%). Statistically significant differences in injury pattern were observed between gender, age groups and season. After logistic regression, predictors of fall included male gender, home setting, and rainy season, whereas predictors of burn included female gender, age 0–5 yrs, home setting, and cold season. Predictors of pedestrian injury included age 6–10 yrs, female, and roadside setting. Predictors of foreign body ingestion included age 0–5 yrs, female gender, home setting, and daytime, and predictors of assault include male gender, age 11–16 yrs, nighttime hours. All predictors were statistically significant (p < 0.05).ConclusionsThis study revealed patterns of injury based upon age, gender, location, and season. Our results may prove useful to stakeholders in injury prevention for designing, evaluating, and implementing programs to improve public safety in children in Malawi and similar resource poor nations

Lung retrieval from non–heart beating cadavers with the use of a rat lung transplant model

AbstractBackground: Lungs retrieved from cadavers after death and circulatory arrest may alleviate the critical shortage of lungs for transplant. We report a rat lung transplantation model that allows serial measurement of arterial blood gases after left single lung transplantation from non–heart beating donors. Methods: Twelve Sprague-Dawley rats underwent left lung transplantation with a vascular cuff technique. Donor rats were anesthetized with intraperitoneal injection of pentobarbital, heparinized, intubated via tracheotomy, and then killed with pentobarbital. Lungs were retrieved immediately or after 2 hours of oxygen ventilation after death (tidal volume 1 mL/100 g, rate 40/min FIO2 = 1.0, positive end-expiratory pressure 5 cm H2O). Recipient rats were anesthetized, intubated, and ventilated. The carotid artery and jugular vein were cannulated for arterial blood gases and infusion of Ringer's lactate (4 mL/h). Anesthesia was maintained with halothane 0.2%, and recipient arterial blood gases were measured at 4 and 6 hours after lung transplantation after snaring the right pulmonary artery for 5 minutes. Animals were put to death 6 hours after lung transplantation, and portions of transplanted lungs were frozen in liquid nitrogen and assayed for wet/dry ratio, myeloperoxidase as a measure of neutrophil infiltration, and conjugated dienes as a measure of free radical–mediated lipid peroxidation. Results: Arterial PO2 and wet/dry ratio were not significantly different in recipients of non–heart beating donor lungs retrieved immediately after death or after 2 hours of oxygen ventilation. Significant neutrophil infiltration was observed in recipients of non–heart beating donor lungs retrieved 2 hours after death from oxygenventilated donors. Conclusions: Strategies to ameliorate reperfusion injury may allow for successful lung transplantation from non–heart beating donors.J Thorac Cardiovasc Surg 2001;122:18-2

Lung retrieval from non–heart beating cadavers with the use of a rat lung transplant model

AbstractBackground: Lungs retrieved from cadavers after death and circulatory arrest may alleviate the critical shortage of lungs for transplant. We report a rat lung transplantation model that allows serial measurement of arterial blood gases after left single lung transplantation from non–heart beating donors. Methods: Twelve Sprague-Dawley rats underwent left lung transplantation with a vascular cuff technique. Donor rats were anesthetized with intraperitoneal injection of pentobarbital, heparinized, intubated via tracheotomy, and then killed with pentobarbital. Lungs were retrieved immediately or after 2 hours of oxygen ventilation after death (tidal volume 1 mL/100 g, rate 40/min FIO2 = 1.0, positive end-expiratory pressure 5 cm H2O). Recipient rats were anesthetized, intubated, and ventilated. The carotid artery and jugular vein were cannulated for arterial blood gases and infusion of Ringer's lactate (4 mL/h). Anesthesia was maintained with halothane 0.2%, and recipient arterial blood gases were measured at 4 and 6 hours after lung transplantation after snaring the right pulmonary artery for 5 minutes. Animals were put to death 6 hours after lung transplantation, and portions of transplanted lungs were frozen in liquid nitrogen and assayed for wet/dry ratio, myeloperoxidase as a measure of neutrophil infiltration, and conjugated dienes as a measure of free radical–mediated lipid peroxidation. Results: Arterial PO2 and wet/dry ratio were not significantly different in recipients of non–heart beating donor lungs retrieved immediately after death or after 2 hours of oxygen ventilation. Significant neutrophil infiltration was observed in recipients of non–heart beating donor lungs retrieved 2 hours after death from oxygenventilated donors. Conclusions: Strategies to ameliorate reperfusion injury may allow for successful lung transplantation from non–heart beating donors.J Thorac Cardiovasc Surg 2001;122:18-2