Tag: Science

Television Viewing, Lifestyle, and Cardiovascular Health among the Yakut (Sakha) of Northeastern Siberia

Presenter: Tyler Barrett

Mentors: Josh Snodgrass, Anthropology; Chris Chávez, Journalism

Oral Presentation

Majors: Anthropology/Media Studies

Culture change has been linked to heightened psychosocial stress among indigenous populations undergoing political-economic transitions, which increases cardiovascular disease risk. However, little is known about how specific aspects of culture change contribute to this relationship. While shifts in media content and exposure have been implicated as a contributing factor to chronic stress in transitioning populations, the relationship between media and cardiovascular health has not been fully examined in this context. The present study investigates links between a style of life (SOL) scale and blood pressure, as well as associations between television viewing hours and myocardial infarction and stroke among 306 Yakut (Sakha) adults (153 men, 153 women) from Berdygestiakh, Sakha Republic, Russia. After controlling for body composition, smoking, and alcohol consumption, SOL was positively correlated with diastolic blood pressure (DBP) among younger (18-49 years) men (P=0.009) and older (≥ 50 years) women (P=0.028) and showed a negative trend with DBP among older men (P=0.054). Further, greater television viewing hours was associated with an increased likelihood of previously experiencing stroke among older adults (P=0.010) and an increased likelihood of previously experiencing myocardial infarction among older men (P=0.047). The rapid change in television content that occurred alongside post-Soviet privatization makes media a particularly salient aspect of culture change among indigenous Siberians, and the present study suggests it may play a role in cardiovascular risk among the Yakut.

Characterization of a Pro-Proliferative Microbiota in Transgenic Drosophila

Presenter: Zoë Wong

Faculty Mentor: Karen Guillemin, Tiffani Jones

Presentation Type: Oral

Primary Research Area: Science

Major: Biology, Psychology

Gastric adenocarcinoma, or stomach cancer, is responsible for the second highest number of cancer-related mortalities. Infection with Helicobacter pylori, a human pathogen, is the strongest risk factor and results in clinical responses that vary from no symptoms, to ulcers, to gastric cancer. One major determinant of disease expression is the presence of a bacterial virulence factor, CagA. Transgenic Drosophila that express the CagA gene were generated in the Guillemin laboratory and can be used to genetically disentangle H. pylori infection from cagA expression. A simple microbial community, short generation time, easily manipulated genome, and the ability to be raised germ-free make Drosophila an ideal model organism.

The goal of my research is to determine the effect of dysbiotic, or altered microbiota of CagA transgenic flies. The dysbiotic microbial community of CagA transgenic flies consists of Lactobacillus brevis and Acetobacter pomoroum. To address this, I reared control and CagA lines germ-free. I inoculated flies with either L. brevis, A. pomorum, or the combined CagA community. Adult flies were dissected after 7 days and gut contents were plated to quantify the abundance of each strain within the gut. Overall, CagA transgenic flies harbored a greater amount of total microbes within their gut, and interestingly flies that received the combined CagA community showed an increased total abundance of microbes regardless of fly genotype.

Evolving a Healthier Worm: Microfluidics, Pharyngeal Pumping, and Experimental Evolution in C. elegans

Presenter: Kelley Williams

Faculty Mentor: Stephen Banse, Patrick Phillips

Presentation Type: Poster 89

Primary Research Area: Science

Major: Biochemistry

Although C. elegans is a popular model for lifespan research, study of genetic and pharmacological interventions that specifically alter healthspan, the length of time an animal stays healthy, is less thorough. We therefore propose to study nematode healthspan using the decline in rhythmic activity of the feeding organ (pharynx) as a selection metric for experimental evolution. To facilitate this project, we are developing three assay platforms based on three microfluidic chips. The first two assay platforms are lower throughput, higher resolution measures of pharyngeal health, while the third is a higher-throughput assay designed for experimental evolution. The first microfluidic device, the “electropharyngeogram chip”, allows us to quantify age-related declines in pharyngeal electrical activity. This approach shows the expected changes in pump frequency and prolonged health of known longevity mutants, as well as shows novel changes in pump patterning. The second device, the “feeding chip”, is designed to provide tight temporal control of food exposure while imaging feeding animals. It also will enable measurements of grinder (chewing) and peristalsis (swallowing) efficiency. The third device, the higher-throughput “sorter chip”, was designed for separating males from females, but now allows automated and programmable selection of high performing individuals from ~2000 animals per hour as measured by ingestion rates. We will present the developmental work for all three devices and for the methods with which we use them, as well as the intellectual framework in which we are using these devices to evolve a worm that stays healthier, longer.

The Effect of Rigid Ankle-Foot Orthotics on Joint Range of Motion and Temporospatial Parameters

Presenter: Therese Wichmann

Faculty Mentor: Shannon Pomeroy, Michael Hahn

Presentation Type: Oral

Primary Research Area: Science

Major: Human Physiology

Ankle arthritis is the debilitating deterioration of the joint cartilage, resulting in pain and diminished quality of life. A surgical fusion of the affected bones can be performed on the ankle to alleviate pain and remove damaged cartilage, but ankle range of motion (ROM) becomes severely limited. Rigid ankle-foot orthotics (AFOs) have had positive outcomes regarding ankle mobility, stability, and pain relief in clinical populations, however, much is unknown about how externally limiting motion affects gait function. This preliminary work will help determine how wearing AFOs affect ROM and temporospatial parameters. We performed standard gait analysis on 16 healthy adult subjects during a baseline walking test without wearing an AFO and throughout thirty minutes of wearing an AFO on a treadmill. Reflective markers were placed on anatomical landmarks to capture segment motion and calculate lower extremity joint angles. Changes in ROM and stride length were analyzed and compared from baseline to minute one, minute fifteen, and minute thirty within the AFO test. Initial results reveal noticeable changes compared to baseline. Continued collections and analysis will be utilized to observe how these acute changes form overtime with AFO use. These data will assist in determining how rigid AFOs maintain normal mobility despite restricting the ankle, potentially giving support to the usage of rigid AFOs in some ankle arthritis cases rather than invasive surgery.

Calibration of the MFR Device

Presenter: Minyuan Wang

Faculty Mentor: Josh Peterson, Frank Vignola

Presentation Type: Poster 87

Primary Research Area: Science

Major: Biochemistry, Human Physiology

Accurate measurements of solar radiation are important for climate modeling, efficient building design, and in the development of solar electric systems. These measurements are performed using instruments that must be calibrated and maintained at the highest quality level. The Multi-Filter Rotating Shadowband Spectroradiometer (MFR) measures three components of incoming solar radiation: light directly from the sun (Direct Irradiance), light coming from everywhere but the sun (Diffuse Irradiance), and light incident from everywhere (Global Irradiance). The MFR device is a unique instrument in that it can make all three of these measurements and does so at six discrete wavelengths. The purpose of this project was to accurately calibrate the MFR device and determine the corresponding uncertainty. To do this, solar radiation data was collected and analyzed from various reference instruments and the MFR in Eugene, Oregon, from June through September 2015 at all times of day throughout the 4-month period. The irradiance measured by the MFR was compared to the reference instruments and the calibration factor of the MFR device was determined. Our results were within 2.5% of the calibration performed in 2013 for each of the six wavelengths the MFR measures with an uncertainty of ±5% at the 95 percent confidence level.

The Ups and Downs of the Mammal World: How Mammal Diversity Has Changed in the United States throughout the 20th Century

Presenter: Kendra Walters

Faculty Mentor: Edward Davis, Samantha Hopkins

Presentation Type: Oral

Primary Research Area: Science

Major: Geology, Biology

Funding Source: Presidential Undergraduate Research Scholar, Undergraduate Research Opportunity Program, $5,000

Biodiversity loss is recognized as a global crisis. Current research strives to create models that predict regions that are at high risk for a significant drop in biodiversity levels. These models must be scaled by analyses of historic changes in biodiversity. However, no study has yet to analyze the changes in mammal richness in the United States at a high enough spatial and temporal resolution to produce a predictive model of mammal diversity. Our research is a high-resolution analysis of the changes in mammal richness in the contiguous United States from 1906 to 1995. We collected mammal occurrence data from the online database VertNet and BISON and individual museum collections, divided it into ten year increments, and used scripts in R to produce sampling-standardized patterns of mammal richness for each decade. We then analyzed the geographic distribution of change in richness over the 20th century. From our results, we were able to determine which regions experienced a significant rise in diversity levels and which experienced a significant drop. We also identified regions where sampling intensities remain too low to conclusively determine how mammal diversity has changed. Regions experiencing the most severe biodiversity changes, as well as those without adequate data, should be focal areas for continued research in conservation efforts.

Vestibular Modulation of the abductor hallucis and abductor digiti minimi Muscles in Response to Changes in Head Position and Visual Cues

Presenter: Jonathan Wallace

Faculty Mentor: Brain Dalton, Marjorie Woollacott

Presentation Type: Oral

Primary Research Area: Science

Major: Human Physiology

Maintaining standing balance involves processing of vestibular, visual, and somatosensory information to produce dynamic motor responses. The purpose of this experiment was to determine if intrinsic foot muscles are modulated by vestibular activity and if the medium-latency responses are altered by changes in head position and visual cues. Indwelling electromyography (EMG) of the abductor hallucis (AH) and abductor digiti minimi (ADM) were sampled while bilateral electrical vestibular stimulation (EVS) was administered to quietly standing participants. Vestibular stimulation delivered on the mastoid processes is interpreted as a true head acceleration which creates a medium- latency vestibular-evoked balance response. A cumulant density function (i.e. cross-correlation) was used to analyze EVS input and the muscle activity (output). When the head was positioned 90◦ to the left with the eyes closed, the medium-latency response amplitude was -0.122 ± 0.027 in the AH and 0.130 ± 0.048 in the ADM. Visual cues reduced the medium-latency amplitude by 14 and 23% in the AH and ADM, respectively (p < 0.05). When the head was oriented 90◦ to the right, the medium-latency response was opposite for the AH (0.101 ± 0.042) and ADM (0.065 ± 0.026, p < 0.05). The inversion and reduction of the medium-latency response with changes to head position and visual input indicate that the vestibular system is modulating activity in the ADM and AH. These results may suggest that the ADM and AH muscles are important contributors to standing balance control.

Force Matching Sense: An Ipsilateral Shoulder Study Investigating the Effect of Torque and Elevation Angle

Presenter: Katya Trousset

Faculty Mentor: Andrew Karduna, David Phillips

Presentation Type: Poster 85

Primary Research Area: Science

Major: Human Physiology

Force matching sense (FMS), or the ability to reproduce a desired force one or more times, is one of three subdivisions that define proprioception. Unlike the other two, joint position sense (JPS) and kinesthesia, FMS is not associated with joint motion (Riemann & Lephart, 2002a). Previous research has found that JPS becomes more accurate as shoulder elevation and external load increases (D. Suprak, Osternig, & Karduna, 2005). The goal of the present study was to investigate how torque and shoulder abduction angle contribute to accuracy of FMS in an ipsilateral remembered force matching task. FMS was tested on the dominant arm of 12 subjects (6 males, 6 females) at three angles (50, 70, and 90 degrees of elevation in the scapular plane), and at 20, 40, and 60 percent above subject baseline torque. It was found that there was no significant change in error due to abduction angle (p > 0.05), but force reproduction error decreased as torque load increased (p < 0.05). From these findings, it appears that FMS does not follow the same pattern as JPS when reproducing a target at different angles, suggesting that these two components must be considered separately when assessing proprioception.

Hip Joint Moment during Obstacle Crossing Following Concussion in Adolescents

Presenter: Austin Thompson

Co-Presenters: Quinn Peterson, David Howell, Li-Shan Chou

Faculty Mentor: Li-Shan Chou, Quinn Peterson

Presentation Type: Poster 84

Primary Research Area: Science

Major: Human Physiology

Patients with concussion often complain of instability while walking. Previous studies have shown that subjects with concussion have altered gait under normal conditions, dual-task walking, and obstacle crossing. While other studies have looked at joint moments in healthy adolescents and the geriatric population and found that older adults have increased hip moment compared to young adults, there has not been a study looking at the changes in joint moment during obstacle crossing in subjects with concussion. The purpose of this study was to determine the effect of concussion on hip joint moment during obstacle crossing in adolescents. It was hypothesized that peak
hip joint moment of the leading and trailing limbs would be increased in patients with concussion. Nine patients with concussion diagnosed by health professionals were matched with eight control subjects by age, height, mass, sex, and sport. Subjects were tested five subsequent times: 72hrs, 1wk, 2wks, 1mo, and 2mo. Twenty-nine retro- reflective markers were placed on boney landmarks, and motion analysis was performed using a 10 camera, 60 Hz system. The subjects stepped over an obstacle 10% of body height during steady state gait, and data was analyzed using Orthotrakä. The neurometabolic cascade of concussion causes changes to motor control, which could lead to unnecessary strain and a mechanism of further injury while providing further insight into how concussions affect gait.

Electron Vortex Beaks With Magnetic Diffraction Gratings

Presenter: Simon Swifter

Faculty Mentor: Benjamin McMorran

Presentation Type: Poster 41

Primary Research Area: Science

Major: Physics, Mathematics

The purpose of this study is to produce and characterize electron vortex beams created by a diffraction grating formed by a magnetization texture. In the past, electrons vortex beams have been produced using nano-fabricated physical diffraction gratings placed in a Transmission Electron Microscope. Professor Benjamin McMorran (University of Oregon) is an expert in the production of these electron beams with a spiraling wave front, or vortex beams. Our objective is to achieve the same vortex beams by instead utilizing magnetic materials as a diffraction grating. In thin samples, Iron Gadolinium (FeGd) has sinusoidal varying magnetic domains with regularly occurring fork defects that make it ideal for use in creating electron vortex beams. Our plan is to find an area where the domains in a sample of FeGd are forked appropriately, and to observe and image the diffraction patterns caused when electrons are transmitted through those points.