Kinetics of Competing Reactions of N-aryl-4-chloro-1,8-naphthalimides with Primary Amines

Color poster with text, diagrams, tables, and graphs.This study presented the mechanistic implications of the kinetics of competing reactions of N-aryl-4-chloro-1,8-naphthalimides with primary amines.University of Wisconsin--Eau Claire Office of Research and Sponsored Programs; Petroleum Research Fund

The impact of college student immersion service learning trips on coping with stress and vocational identity

This study examined the impact of service learning immersion trips on vocational identity and coping with stress among college students. Fifty-one students (15 males, 36 females) who participated in immersion trips and 76 students (25 males, 51 females) in a non-immersion control group completed a series of questionnaires directly before and immediately after both fall and spring break immersion trips, and during a four-month follow up. Results suggest that, after returning from an immersion trip, students report a greater ability to cope with stress and a somewhat stronger sense of vocational identity relative to students who do not participate in immersion trips

New Modeling Approaches to Study DNA Damage by the Direct and Indirect Effects of Ionizing Radiation

DNA is damaged both by the direct and indirect effects of radiation. In the direct effect, the DNA itself is ionized, whereas the indirect effect involves the radiolysis of the water molecules surrounding the DNA and the subsequent reaction of the DNA with radical products. While this problem has been studied for many years, many unknowns still exist. To study this problem, we have developed the computer code RITRACKS [1], which simulates the radiation track structure for heavy ions and electrons, calculating all energy deposition events and the coordinates of all species produced by the water radiolysis. In this work, we plan to simulate DNA damage by using the crystal structure of a nucleosome and calculations performed by RITRACKS. The energy deposition events are used to calculate the dose deposited in nanovolumes [2] and therefore can be used to simulate the direct effect of the radiation. Using the positions of the radiolytic species with a radiation chemistry code [3] it will be possible to simulate DNA damage by indirect effect. The simulation results can be compared with results from previous calculations such as the frequencies of simple and complex strand breaks [4] and with newer experimental data using surrogate markers of DNA double ]strand breaks such as . ]H2AX foci [5]

Monte-Carlo Simulation of Heavy Ion Track Structure Calculation of Local Dose and 3D Time Evolution of Radiolytic Species

Heavy ions have gained considerable importance in radiotherapy due to their advantageous dose distribution profile and high Relative Biological Effectiveness (RBE). Heavy ions are difficult to produce on Earth, but they are present in space and it is impossible at this moment to completely shield astronauts from them. The risk of these radiations is poorly understood, which is a concern for a 3-years Mars mission. The effects of radiation are mainly due to DNA damage such as DNA double-strand breaks (DSBs), although non-targeted effects are also very important. DNA can be damaged by the direct interaction of radiation and by reactions with chemical species produced by the radiolysis of water. The energy deposition is of crucial importance to understand biological effects of radiation. Therefore, much effort has been done recently to improve models of radiation tracks

Discriminating Between Copers and those with Chronic Ankle Instability with Clinical Outcomes

Introduction: Chronic ankle instability (CAI) is a common consequence of lateral ankle sprains and a leading cause of post-traumatic ankle osteoarthritis. Despite a history of a lateral ankle sprain, there are some individuals (copers) who appear to have a mechanism that allows them to avoid recurrent lateral ankle sprains and giving way episodes. To date, research has identified differences in perceptual (e.g. self-assessed disability), mechanical (e.g. ligament laxity), and sensorimotor (e.g. balance) outcomes between copers and those with CAI. However, the vast majority of these outcomes are considered research and/or laboratory based and thus impractical for most clinicians to use on a daily basis. The identification of clinical tools, capable of discriminating between copers and those with CAI is the first step in developing an accurate clinical battery of tests that can be used to predict patients more likely to develop CAI after an initial lateral ankle sprain. Therefore, the purpose of this investigation was to establish the ability of clinical outcome measures to discriminate between copers and those with CAI. Methods: Participants- A total of 46 participants (21 copers and 25 with CAI) were enrolled and completed the investigation. All participants read and signed the university approved informed consent document prior to participation. All subjects were between the ages of 18-30 and participated in recreational activity for at least 90 minutes each week. Copers and those with CAI had a history of at least one moderate to severe ankle sprain that required acute care. Copers resumed all pre-injury activity without limitation and without recurrent episodes of injury/giving way for at least 12 months prior to testing and scored \u3e24 on the ankle joint functional assessment tool (AJFAT). In comparison, those with CAI had at least one recurrent sprain within 6 months of testing and scored \u3c20 on the AJFAT. Protocol: Perceptual outcomes, the Foot Ankle Ability Measure (FAAM) and FAAM Sport (FAAM-S) were completed first. These questionnaires determine a subject’s self-assessed limitations during daily and physical activities and lower scores represent greater disability. Next, mechanical adaptations were assessed via the the weight bearing lunge test (WBLT) and talar glide test. The WBLT measured ankle dorsiflexion range of motion using a modified lunge technique. Maximum dorsiflexion was defined as the furthest distance the subject’s foot could be from a wall while the subject’s knee was in contact with the wall and the subject’s heel was flat on the ground. The talar glide test measures the magnitude of the talus’ posterior glide by measuring the change in passive knee flexion, from 90°, while an examiner simultaneously pushes the talus posteriorly and pulls the foot into dorsiflexion until the point of capsular restriction. Finally, sensorimotor dysfunction was assessed with the Star Excursion Balance Test (SEBT) and isometric strength testing. The SEBT is a measure of dynamic postural control and measures the distance a subject can reach with their contralateral leg without losing their balance. Reach distance was defined as the farthest point that an individual could touch without accepting weight on their reach leg and maintaining balance through the return to a bilateral stance. Reach distance was normalized to each subject’s leg length. Using a handheld dynamometer, ankle dorsiflexion, plantar flexion, eversion, and inversion strength was assessed during 3-second maximal contractions. Strength was normalized to a subject’s body weight. Statistical Analysis: Group differences in perceptual, mechanical, and sensorimotor outcomes were assessed with independent sample t-tests. If significance was achieved, the ability of an outcome to accurately discriminate between the groups was then assessed using the area under the curve (AUC) for receiver operating characteristic (ROC) curves. A ROC curve illustrates the “trade-off” between sensitivity and specificity throughout a measure’s entire range of values. Finally, clinical meaningfulness was established by the calculation of cut-off scores and likelihood ratios for outcomes that successfully discriminated between copers and those with CAI. A traditional level of significance (=0.05) was used for all analyses. RESULTS: The CAI group had significant perceptual and sensorimotor deficits relative to the coper group. Specifically, FAAM (Coper: 99.0±2.5%, CAI: 89.2±9.5%), FAAM-S (Coper: 96.6±4.1%, CAI: 79.3±16.2%), normalized posteriomedial SEBT reach distance (Coper: 91.2±8.1%, CAI: 83.5±6.5%), and normalized dorsiflexion strength (Coper: 74.5±19.9%, CAI: 62.9±12.8%) were lower in those with CAI relative to copers. The secondary analysis revealed that the FAAM (P\u3c0.01), FAAM-S (p\u3c0.01), and posteriomedial SEBT reach distance (p\u3c0.01) accurately discriminated between copers and those with CAI. The AUC scores, cut-off scores, and likelihood ratios can be seen in the table below. No differences existed with regards to talar glide, range of motion, anterior SEBT reach, posteriolateral SEBT reach, and normalized eversion, inversion, or plantar flexion strength. Outcome Measure Category AUC Cut-off Score Likelihood Ratios (95% Confidence Intervals) Positive Negative FAAM 0.93 99% 5.05 (2.92 to 10.36) 0.05 (0.01 to 0.21) FAAM-S 0.90 88% 31.00 (4.42 to 217.67) 0.33 (0.22 to 0.51) Posteriomedial SEBT Reach 0.79 89% 2.53 (1.77 to 3.79) 0.06 (0.02 to 0.27) DISCUSSION: The results of this investigation indicate that perceptual (FAAM, FAAM-S) and some sensorimotor outcomes (posteriomedial SEBT reach distance) can discriminate between copers and those with CAI. We hypothesize that these outcome measures represent part of the mechanism that 1) allows copers to function as if uninjured and 2) is absent in individuals who develop CAI. The current results, using clinical outcome measures, support previous findings that have illustrated perceptual and sensorimotor deficits using research and/or laboratory based outcomes. Further, because a variety of the current outcomes (perceptual and sensorimotor) successfully discriminated between copers and those with CAI, groups, the current findings support the theory that the causal mechanism of CAI is multi-factorial in nature. However, the most important finding of the current investigation is that the perceptual outcomes demonstrated the greatest ability to discriminate between copers and those with CAI with accuracy point estimates ranging from 0.90-0.93. Indeed, the perceptual outcomes (as a whole) demonstrated higher AUC estimates and positive likelihood ratios, as well as lower negative likelihood ratios compared with the sensorimotor outcomes (as a whole). This finding, which supports previous results, indicates that perceptual outcomes have the greatest ability to accurately predict those who became copers after initial lateral ankle sprain. Given the magnitude of the positive and negative likelihood ratios, we believe that perception based outcomes, such as the FAAM and FAAM-S, should be used in future longitudinal research investigations designed to determine if and when, post-injury, these outcomes can predict who will develop CAI after an initial lateral ankle sprain

Monte-Carlo Simulations of Heavy Ions Track Structures and Applications

In space, astronauts are exposed to protons, high ]energy heavy (HZE) ions that have a high charge (Z) and energy (E), and secondary radiation, including neutrons and recoil nuclei produced by nuclear reactions in spacecraft walls or in tissue. The astronauts can only be partly shielded from these particles. Therefore, on travelling to Mars, it is estimated that every cell nucleus in an astronaut fs body would be hit by a proton or secondary electron (e.g., electrons of the target atoms ionized by the HZE ion) every few days and by an HZE ion about once a month. The risks related to these heavy ions are not well known and of concern for long duration space exploration missions. Medical ion therapy is another situation where human beings can be irradiated by heavy ions, usually to treat cancer. Heavy ions have a peculiar track structure characterized by high levels of energy ]deposition clustering, especially in near the track ends in the so ]called eBragg peak f region. In radiotherapy, these features of heavy ions can provide an improved dose conformation with respect to photons, also considering that the relative biological effectiveness (RBE) of therapeutic ions in the plateau region before the peak is sufficiently low. Therefore, several proton and carbon ion therapy facilities are under construction at this momen

Step-by-Step Simulation of Radiation Chemistry Using Green Functions for Diffusion-Influenced Reactions

Radiolytic species are formed approximately 1 ps after the passage of ionizing radiation through matter. After their formation, they diffuse and chemically react with other radiolytic species and neighboring biological molecules, leading to various oxidative damage. Therefore, the simulation of radiation chemistry is of considerable importance to understand how radiolytic species damage biological molecules [1]. The step-by-step simulation of chemical reactions is difficult, because the radiolytic species are distributed non-homogeneously in the medium. Consequently, computational approaches based on Green functions for diffusion-influenced reactions should be used [2]. Recently, Green functions for more complex type of reactions have been published [3-4]. We have developed exact random variate generators of these Green functions [5], which will allow us to use them in radiation chemistry codes. Moreover, simulating chemistry using the Green functions is which is computationally very demanding, because the probabilities of reactions between each pair of particles should be evaluated at each timestep [2]. This kind of problem is well adapted for General Purpose Graphic Processing Units (GPGPU), which can handle a large number of similar calculations simultaneously. These new developments will allow us to include more complex reactions in chemistry codes, and to improve the calculation time. This code should be of importance to link radiation track structure simulations and DNA damage models