Mountain Scholar :: Browsing by Author "Walrond, John, committee member"

Browsing by Author "Walrond, John, committee member"

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Open Access
Characterization of the dissociation equilibria of the histone H3H4 tetramer using sedimentation velocity analytical ultracentrifugation
(Colorado State University. Libraries, 2020) Connolly, Mark Edward, author; Hansen, Jeffrey, advisor; Nyborg, Jennifer, committee member; Walrond, John, committee member
By performing sedimentation velocity analytical ultracentrifugation experiments under various ionic and pH conditions the kd can be measured. This system was found to be pH dependent with a change of Svedberg (S) value distribution in between pH 5.2 and pH 5.5. The H3H4 system was found to be an interacting one due to the change in S value distribution with increasing the histone protein concentration. We found that the S value distribution is highly dependent on the ionic conditions of the solution with 2M NaCl solution showing higher S values then 5mM KPO4 solution at the same concentration and pH. Oddly enough adding HEPES to a KPO4 buffer will destabilize the H3H4 species present with 5mM KPO4 having a higher S value distribution than 5mM KPO4 10mM HEPES at the same concentration and pH. I was unable to model these systems to a H3H4 dimer to tetramer equilibrium model which leads me to believe the conditions I was using did not stabilize the tetramer save for the 2M NaCl.
Open Access
Investigation of tritium atom exchange in plastic liquid scintillation vials
(Colorado State University. Libraries, 2018) Wang, John Jen-Chiang, author; Brandl, Alexander, advisor; Sudowe, Ralf, committee member; Walrond, John, committee member
Tritium is a naturally occurring radionuclide; it is an analyte of interest in many air, soil, and water samples. It has been shown that long term storage and study of tritium samples results in a reduction in tritium activity not attributed to the natural radioactive decay. Several explanations have been offered through past literatures including diffusion, LSC cocktail degradation, and change in quenching effects. Another possible explanation for the decrease in activity is that tritium may have been organically bound to the plastic possibly due to exchangeable hydrogen atoms along the plastic carbon chain. The hypothesis that tritium can be incorporated into the plastic, interchanging the 1H atoms in the plastic with 3H atoms, was experimentally tested. The experiment consisted of adding deionized water into a previously used plastic vial which had contained tritium to determine if the deionized water had now become tritiated. The results showed that the longer the tritiated water is stored in the vials, the greater the loss of tritium activity in plastic vials is compared to glass vials. An increase in the time that the tritiated water is stored also increases the activity of the tritium found in the deionized water in plastic vials but not in the glass vials. The combination of these two observations supports the hypothesis that tritium exchange may have occurred between the tritiated water and the hydrogen within the plastic vials.
Open Access
Long term stability of sensation thresholds from 10 millisecond pulses of 2.01 micrometer laser light
(Colorado State University. Libraries, 2013) Scott, Ernie, author; Johnson, Thomas, advisor; Brandl, Alex, committee member; Walrond, John, committee member
Current methods for diagnosing and evaluating efficacy for treatment of diabetic neuropathy either give only subjective data or are invasive. However, the use of laser induced sensations to evaluate threshold sensations gives precisely quantifiable and reproducible stimulus and is 100% non-invasive. In this study we evaluated whether or not laser sensation thresholds were stable in 12 human subjects over a four month period of time. Subjects' hands and feet were exposed over eight different exposure sessions to 10 ms pulses of laser light produced by a 50 W Tm: YAG laser system. Sensation threshold values (in mJ/mm2) were determined for each session and compared by regression analysis. The results showed an upward trend in sensation thresholds over time in the majority of the subject's hands and feet, indicating that laser sensation thresholds are not stable over time. Subject desensitization to the sensation over time combined with too short a time between exposures, or variations in baseline skin temperature of the exposure site due to changes in weather are discussed as possible causes of the upward trend. Finally, suggestions are made for future studies to include a study over a longer period of time with more time between exposure sessions and more subjects as well as a study where the exposure sites are heated/cooled to a standardized baseline temperature prior to each exposure session.
Open Access
Long-term hematopoietic response in leukocyte counts and differentials for rhesus macaques (Macaca mulatta) from acute whole-body radiation exposure
(Colorado State University. Libraries, 2023) Chino, Yuiko, author; Johnson, Thomas, advisor; Bailey, Susan, committee member; Kato, Takamitsu, committee member; Walrond, John, committee member
Accumulating evidence from A-bomb survivors and radiation therapy patients suggest that survivors are at risk of developing delayed effects of acute radiation exposure (DEARE). In contrast to acute radiation syndrome (ARS), the underlying mechanisms of DEARE are largely unknown. Better understanding of DEARE is vital for improving estimates of risk and predictions of long-term health outcomes following a variety of radiation exposure scenarios, whether accidental or intentional, and including nuclear accidents, cancer treatment, and space travel. The hematopoietic system is highly sensitive to ionizing radiation (IR) exposure; leukocyte counts reach a nadir in days to several weeks post-acute exposure, followed by a recovery period from 4-8 weeks to a year. Accumulating evidence from the A-bomb survivor cohort and animal studies suggests residual damage in the hematopoietic system persists for a long time. Long-term effects in hematopoietic system are very likely the underlying cause of DEARE disease, although there is limited understanding of the process. In this study, archival leukocyte counts and differentials from the Non-Human Primate Radiation Late Effects Cohort (RLEC), were analyzed to evaluate long-term effects. The RLEC cohort consists of over 200 Rhesus Macaques (Macaca mulatta) previously exposed to acute whole body irradiation from 1.14 to 8.5 Gy and approximately 50 control animals. The dataset was created from blood sampling started approximately 1 year post-exposure and continued every 2-6 months. Linear mixed models were developed for total leukocyte count and the differentials including neutrophil, lymphocyte, and monocyte counts and their percentages. Preliminary analysis was conducted for animals with the same dose level, sex, and age at the time of exposure and age and sex matched control animals. The linear mixed models had statistically significant elevations in leukocyte and neutrophil counts and neutrophil% in irradiated animals compared to the controls. Lymphocyte% was significantly lower in irradiated animals. Longitudinal trends for both control and irradiated animals were consistent with expected trends of aging in hematopoiesis, which is skewed towards production of myeloid lineage cells such as neutrophils and monocytes rather than lymphoid cells. There was no statistical difference among the longitudinal trends of control and irradiated animals. Next analysis was extended from the preliminary analysis with a larger dataset including animals with different dose, sex, age at the time of exposure, as well as mitigator assignment. Longitudinal trends were estimated for different dose levels (control, LD50; 6.8 to 8.5 Gy), and adjusted for sex, age at the time of exposure, and status of mitigator use. All models suggested that dose levels were a statistically significant factor for the longitudinal trends of leukocytes and the differentials. Controls showed a slight decrease of total leukocyte count and monocyte skewed differentiation, consistent with changes estimated from aging in hematopoietic system. The LD50 animals than controls and
Open Access
Pseudo Pelger-Huët anomalies as potential biomarkers for acute radiation dose in rhesus macaques (Macaca mulatta)
(Colorado State University. Libraries, 2021) Hayes, Joshua Michael, author; Johnson, Thomas E., advisor; Bailey, Susan, committee member; Brandl, Alexander, committee member; Walrond, John, committee member
The potential for malicious use of radiation, or radiation accidents could potentially lead to acute, high radiation doses to members of the public. Following an acute accidental exposure to high doses of radiation, medical intervention is pivotal to the survivability of the patient and the sooner the appropriate measures are taken the better the odds for survival. Early estimates of acute accidental radiation doses can be determined via biomarkers such as dicentric chromosome analysis or scenario reconstruction using computer software. However, both take valuable time, and can be expensive. Here, potentially faster, and cheaper quantitative biomarkers for radiation exposure were evaluated in acutely exposed Rhesus Macaques from the Wake Forest School of Medicine, Department of Comparative Medicine. Increased frequencies of abnormal neutrophils in peripheral blood, referred to as pseudo Pelger-Huët anomalies (PPHAs), have been shown to be potential biomarkers of radiation exposure in several scenarios, including the 1958 Y-12 criticality accident and the radium dial painters. We have confirmed the PPHA morphology to be present in Rhesus Macaques and a dose response curve, a biokinetics model, and determination of background prevalence of the morphology has been constructed utilizing peripheral blood smears. The dose response curve consists of macaques that received doses ranging from 0 Gy to 8.5 Gy (LD90/30) and a blood smear at a common time point post-irradiation. The biokinetics model utilized only 4 Gy exposures and blood smears taken periodically over 3.1 years post-irradiation. Results show a linear correlation between PPHA concentration and acute radiation dose and the PPHA morphology appears stable over 3.1 years post-irradiation.
Open Access
The effect of music therapy on infants born with gastroschisis
(Colorado State University. Libraries, 2013) Wenszell, Melissa J., author; LaGasse, Blythe, advisor; Davis, William, committee member; Walrond, John, committee member
Gastroschisis is a congenital anomaly characterized by a hole in the abdominal wall. Through this hole intestines and abdominal organs protrude requiring these infants to have surgery shortly after birth. Both preoperatively and postoperatively, infants born with gastroschisis require pain medications and ventilator support, intravenous feedings and endure long hospital stays. These infants often continue to experience constant discomfort, difficulty in eating, and may develop bowel problems and other complications such as sepsis. Music therapy is an established mode of treatment to promote individual wellness, healing and change. Live lullaby style music was provided on the guitar and / or reverie harp with humming and vocals to infants with gastroschisis postoperatively up to three times a week for 25 minutes followed by 30 minutes of quiet time. The infant's physiological parameters of heart rate, respiration and oxygen saturation were measured pre, during and post music therapy along with a behavioral and pain assessment tool, the CRIES scale. Seven infants were enrolled in the study and 29 music therapy sessions were conducted. The average heart rate, respiratory rate and the CRIES score between pre and post music therapy was compared using the paired t-test. A two-sided p-value < 0.05 was used as the significance level. With physiological parameters and CRIES both at .05 (p<0.05) respectively, statistical significance was found only for respiration rate during the post intervention 30 minutes of quiet time p=0.0047. Statistical significance on the effect of music therapy for parameters of heart rate, saturation and CRIES was not found on infants born with gastroschisis. If a caregiver was present for the music therapy session, a Likert-type scale survey was provided to rate the experience of the live music for the parent and their perception of benefit to their child. Caregivers observed only four sessions and each completed survey had been awarded the maximum of 30 points, therefore, the perception was high that music therapy had positive benefits for both the infant and the caregiver. More research in the effect of music therapy on infants is needed. Within the gastroschisis population, no other study is available, and this data may provide a small foundation toward further study. While overall statistical significance was not found, acute effects were noted in behavioral changes of these medically compromised infants.
Open Access
The effect of music therapy on the anxiety levels of women awaiting breast cancer surgery
(Colorado State University. Libraries, 2014) Palmer, Jaclyn Bradley, author; Lagasse, Blythe, advisor; Thaut, Michael, committee member; Walrond, John, committee member
Breast cancer is a leading cause of death in females. Women encountering the combination of surgery and prospective cancer may be faced with intense anxiety. As a familiar and aesthetic medium, music has the ability to ease anxiety, act as a diversion, and dispel the fear that accompanies the unknown (Stevens, 1990). The purpose of this study was to assess the effects of live and recorded music on the perceived anxiety of women awaiting breast cancer surgery. In this study, 86 women were randomized into a control and two experimental groups. Treatment groups received either live or recorded preferred music in addition to standard care in the preoperative unit, while the control group received standard care alone. A one-way ANOVA comparison revealed that the addition of either live or recorded music facilitated by a board certified music therapist significantly reduced patient-perceived anxiety (p = 0.001) more than standard care alone. The findings here may provide a basis for future research where further evidence can be established by developing a more controlled alternative to 'standard care' and by investigating different surgical populations at a multitude of diverse medical institutions.
Open Access
The pseudo Pelger-Huët anomoly as a potential biomarker for chronic low-dose radiation exposures of Sus scrofa leucomystax and Apodemus speciosus
(Colorado State University. Libraries, 2018) Hayes, Joshua Michael, author; Johnson, Thomas E., advisor; Bailey, Susan, committee member; Walrond, John, committee member
On March 11, 2011 a 9.0 earthquake struck off the east coast of Japan, resulting in a near 20-foot Tsunami that devastated the coastline. Among the damage was the Fukushima-Daiichi nuclear reactor which over pressurized, due to failed cooling systems, leading to the release of a plume of radionuclides into the surrounding environment that included Iodine-131, Cesium-134, and Cesium-137. The people of the region were immediately evacuated, many of whom have still not returned to the exclusion zone, leaving nature to take over. Many wildlife populations, including the Large Japanese Field Mouse (Apodemus speciosus) and Wild Boar (Sus scrofa leucomystax) have begun to thrive in the region largely due to the absence of human influence. The contaminated environment in which these animals live provides a unique opportunity for radiobiological research involving chronic low dose exposures, similar to those that human inhabitants of Fukushima Prefecture and radiation workers are likely to experience. Here, quantitative bio-dosimetry was employed to evaluate environmental radiation exposure in two wildlife species. Specifically, frequencies of abnormal neutrophils referred to as pseudo Pelger-Huët anomalies (PPHAs) in peripheral blood of the large Japanese field mouse and wild boar living in exclusion zone and control zones. PPHAs have been shown to be informative biomarkers of radiation exposure in several scenarios, including archived slides from the 1958 Y-12 criticality accident, the radium dial painters from the first half of the 20th century, and chronically exposed bats in South African caves containing high levels of thorium. The PPHA morphology was indeed confirmed in the blood of exposed wild boars, however PPHAs did not occur in the large Japanese field mouse. In the future, this PPHA approach needs to be compared to other quantitative methods of estimating dose to wildlife, e.g., dicentric chromosome analysis. The potential impacts of this study include influencing the time frame in which the people of Fukushima can return to their homes, as well as reducing the cost incurred for bio-dosimetric analyses in the event of accidental or occupational radiation exposure.

Browsing by Author "Walrond, John, committee member"

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