Matching Items (38)
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Description
Preliminary studies indicate that the use of dietary menthol may prevent excessive weight gain through the activation of the transient receptor potential melastatin family member 8 (TRPM8) ion channel. It has also been expressed that elevation of the core temperature (Tc) inducing mild hyperthermia via an increase in ambient temperature

Preliminary studies indicate that the use of dietary menthol may prevent excessive weight gain through the activation of the transient receptor potential melastatin family member 8 (TRPM8) ion channel. It has also been expressed that elevation of the core temperature (Tc) inducing mild hyperthermia via an increase in ambient temperature aids in a marked reduction of the drive to eat and weight gain. While caloric restriction (CR) aims to treat obesity and secondary sicknesses, weight regain is a common result during long term weight maintenance. The goal of these studies was to evaluate and identify if the menthol and mild hyperthermia mechanisms could couple synergistically to reduce or abrogate weight gain. Ambient temperature (Ta) was increased incrementally to identify the threshold in which rodents display mild hyperthermia. Our initial attempts at hyperthermia induction failed because of limitations in the environmental chamber. These trials fail to note a threshold at which elevated Tc is sustained for any period of time. The data suggests an ambient temperature of 36-38 °C would be appropriate to induce a mild hyperthermia. A mild hyperthermia is described as the elevation of Tc 2-3 ° above the hypothalamic set point. To facilitate future hyperthermia studies, an environmental chamber was designed. A wine cooler was converted to withstand the desired temperatures, through the use of heat tape, a proportional controller, and a translucent Plexiglas custom fit door. Beyond leveraging temperature to regulate weight gain, dietary changes including a comparison between standard chow food, high fat diet, and menthol supplemented chow food treatment illustrate a strong likelihood of weight gain variability. In this pilot study, weight gain expression when given a diet supplemented with menthol (1%) showed no statistical significance relative to a high fat diet nor chow food, however, it revealed a trend of reduced weight gain. It is assumed the combination of supplemental menthol and mild hyperthermia induction will exacerbate their effects.
ContributorsJohnsson, Kailin Alexis (Author) / Van Horn, Wade (Thesis director) / Herman, Richard (Committee member) / Towe, Bruce (Committee member) / Sanford School of Social and Family Dynamics (Contributor) / School of Life Sciences (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
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Description
Ion channels in the membranes of cells in the body allow for the creation of action potentials from external stimuli, allowing us to sense our surroundings. One particular channel, TRPM8, is a trans-membrane ion channel believed to be the primary cold sensor in humans. Despite this important biological role and

Ion channels in the membranes of cells in the body allow for the creation of action potentials from external stimuli, allowing us to sense our surroundings. One particular channel, TRPM8, is a trans-membrane ion channel believed to be the primary cold sensor in humans. Despite this important biological role and intense study of the channel, TRPM8 is not fully understood mechanistically and has not been accurately modeled. Existing models of TRPM8 fail to account for menthol activation of the channel. In this paper we re-implement an established whole cell model for TRPM8 with gating by both voltage and temperature. Using experimental data obtained from the Van Horn lab at Arizona State University, we refined the model to represent more accurately the dynamics of the human TRPM8 channel and incorporate the channel activation through menthol agonist binding. Our new model provides a large improvement over preexisting models, and serves as a basis for future incorporation of other channel activators of TRPM8 and for the modeling of other channels in the TRP family.
ContributorsAckerman, David (Author) / Crook, Sharon (Thesis director) / Van Horn, Wade (Committee member) / School of Earth and Space Exploration (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
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Description
This study was conducted to observe the effects of varying diets on weight regain after caloric restriction. Touted as a potentially effective non-invasive treatment to obesity, caloric restriction uses the gradual decrease in caloric intake to aid in weight loss. However, once a patient is taken off caloric restriction, a

This study was conducted to observe the effects of varying diets on weight regain after caloric restriction. Touted as a potentially effective non-invasive treatment to obesity, caloric restriction uses the gradual decrease in caloric intake to aid in weight loss. However, once a patient is taken off caloric restriction, a marked regain of weight regain occurs, nullifying the weight loss from caloric restriction. To find ways to suppress this weight regain, this study observed the effects of four different diets: low-fat diet (chow), high-fat diet (HFD), 0.5% concentration menthol infused chow, and 1% concentration menthol infused chow. Over a span of 3 years, 43 male Sprague-Dawley rats were placed through a strict feeding protocol: 3 weeks of chow food (3.1 kcal/gram), 8 or 12 weeks of HFD (5.42 kcal/gram), and caloric restriction for 4 weeks. Separate data analysis was conducted for the year 2017-2018, due to a slightly different protocol when compared to 2018-2019 and 2019-2020.

In 2017-2018, the results showed that 0.5% menthol (n=4) suppressed weight gain more effectively than both the baseline chow diet (n=4, p=0.022) and the HFD (n=4, p=0.027). Again in 2018-2020, the 0.5% menthol (n=6) showed promising results, showing significant suppression of weight gain when compared to chow (n=13, p=0.022). Unfortunately, the difference in weight gain in 1% menthol (n=6) was inconclusive when comparing to both chow and HFD. Although 1% menthol was inconclusive in its efficacy in suppressing weight regain, the promising results on 0.5% menthol show that menthol has the potential to be an effective treatment to both prevent rapid weight gain and maintain weight loss from caloric restriction.
ContributorsLee, Justin (Author) / Van Horn, Wade (Thesis director) / Baluch, Debra (Committee member) / Herman, Richard (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
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Description
The transient receptor potential channel subfamily V member 1 (TRPV1) functions as the heat and capsaicin receptor. It can be activated by heat, protons, pungent chemicals, and a variety of other endogenous mediators of nociception. TRPV1 is a non-selective cation channel consisting of 6 transmembrane domains (S1-S6), with helices S1-S4

The transient receptor potential channel subfamily V member 1 (TRPV1) functions as the heat and capsaicin receptor. It can be activated by heat, protons, pungent chemicals, and a variety of other endogenous mediators of nociception. TRPV1 is a non-selective cation channel consisting of 6 transmembrane domains (S1-S6), with helices S1-S4 forming the sensing domain and the S5-S6 helices forming the pore domain. Understanding the TRPV1 channel is imperative due to its relation to a variety of human diseases, including cancer, type II diabetes, hyper and hypothermia, and inflammatory disorders of the airways and bladder. Although TRPV1 is the best-studied thermosensitive-TRP channels of all the 28 family members, the molecular underpinning and the contributions of the human TRPV1 pore domain in thermo-sensing remains elusive. Recently, the human TRPV1 sensing domain was found to contribute to heat activation. It was found to undergo a non-denaturing temperature-dependent conformational change. This finding triggered interest in studying the function and the role of the human TRPV1 pore domain in the heat activation process. Specifically, to identify whether heat activation is intrinsic to the pore domain. This thesis paper explores and optimizes the purification protocol of the human TRPV1 pore domain through three different methods. The first method was using a denaturant, the second method was increasing the length of the histidine tags through Q5 insertion, and the third method was incorporating the protein construct into nanodiscs. In addition to the above three methods, size exclusion chromatography and ion-exchange chromatography were utilized after thrombin cleavage to separate the human TRPV1 pore domain from the cleaved MBP deca-histidine tags as well as the impurities.
ContributorsChang, Yu Tzu (Author) / Van Horn, Wade (Thesis director) / Wang, Xu (Committee member) / Cherry, Brian (Committee member) / School of Molecular Sciences (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-12
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Description
Ribulose-1,5-bisphosphate carboxylase/oxygenase enzyme (Rubisco) is responsible for the majority of carbon fixation and is also the least efficient enzyme on Earth. Rubisco assists 1,5-ribulose bisphosphate (RuBP) in binding CO2, however CO2 and oxygen have similar binding affinities to Rubisco, resulting in a low enzymatic efficiency. Rubisco activase (Rca) is an

Ribulose-1,5-bisphosphate carboxylase/oxygenase enzyme (Rubisco) is responsible for the majority of carbon fixation and is also the least efficient enzyme on Earth. Rubisco assists 1,5-ribulose bisphosphate (RuBP) in binding CO2, however CO2 and oxygen have similar binding affinities to Rubisco, resulting in a low enzymatic efficiency. Rubisco activase (Rca) is an enzyme that removes inhibiting molecules from Rubisco’s active sites, promoting the Rubisco activity. The binding of Rubisco and Rca stimulates a high-rate of carbon fixation and lowers the overall CO2 concentration in the atmosphere. To study the interaction between the two complexes, Rubisco was extracted from baby spinach (Spinacia oleracea) and purified using anion-exchange chromatography and size-exclusion chromatography. Rca was designed to use a recombinant gene and overexpressed in Escherichia coli (E. coli). The purified proteins were verified using SDS-PAGE. The two proteins were assembled in vitro and the interaction of the protein complex was stabilized using glutaraldehyde cross-linking. The samples were then deposited on a carbon-coated electron microscopy (EM) grid, stained with uranyl formate, and observed under a transmission electron microscope (TEM). The ultimate goal is to image the specimen and reconstruct the structure of the protein complex at high resolution.
ContributorsHart, Hayden (Author) / Chiu, Po-Lin (Thesis director) / Redding, Kevin (Committee member) / Van Horn, Wade (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor) / Department of Military Science (Contributor)
Created2022-05
Description

In intracranial aneurysms, multiple factors and biochemical pathways are believed to be involved in the event of a rupture. The epidermal growth factor receptor (EGFR) activation pathway is of particular interest as a way to understand and target the mechanism of rupture due to its established role in cellular proliferation

In intracranial aneurysms, multiple factors and biochemical pathways are believed to be involved in the event of a rupture. The epidermal growth factor receptor (EGFR) activation pathway is of particular interest as a way to understand and target the mechanism of rupture due to its established role in cellular proliferation and inflammation. Furthermore, unfolded protein responses in vascular cells’ endoplasmic reticulum (ER), known as ER stress, have emerged as a potential downstream mechanism by which inflammatory EGFR activation may lead to aneurysm rupture. The purpose of this project was to investigate the role of EGFR inhibition on the aneurysm rupture rate in a preclinical model, investigate the role of ER stress induction on the aneurysm rupture rate, and confirm which cellular phenomenon lies upstream in this mechanistic cascade. Based on analyses of aneurysm rupture rate and gene expression in the Circle of Willis, ER stress and inflammatory unfolded protein responses were found to be downstream of initial EGFR activation, which may be an effective therapeutic target for preventing aneurysm rupture in a clinical setting.

ContributorsPolen, Kyle (Author) / Van Horn, Wade (Thesis director) / Martin, Thomas (Committee member) / Hashimoto, Tomoki (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor) / School of Human Evolution & Social Change (Contributor)
Created2022-12
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Description

Synthetic genetics is a subdiscipline of synthetic biology that aims to develop artificial genetic polymers (also referred to as xeno-nucleic acids or XNAs) that can replicate in vitro and eventually in model cellular organisms. This field of science combines organic chemistry with polymerase engineering to create alternative forms of DNA

Synthetic genetics is a subdiscipline of synthetic biology that aims to develop artificial genetic polymers (also referred to as xeno-nucleic acids or XNAs) that can replicate in vitro and eventually in model cellular organisms. This field of science combines organic chemistry with polymerase engineering to create alternative forms of DNA that can store genetic information and evolve in response to external stimuli. Practitioners of synthetic genetics postulate that XNA could be used to safeguard synthetic biology organisms by storing genetic information in orthogonal chromosomes. XNA polymers are also under active investigation as a source of nuclease resistant affinity reagents (aptamers) and catalysts (xenozymes) with practical applications in disease diagnosis and treatment. In this review, we provide a structural perspective on known antiparallel duplex structures in which at least one strand of the Watson–Crick duplex is composed entirely of XNA. Currently, only a handful of XNA structures have been archived in the Protein Data Bank as compared to the more than 100 000 structures that are now available. Given the growing interest in xenobiology projects, we chose to compare the structural features of XNA polymers and discuss their potential to access new regions of nucleic acid fold space.

ContributorsAnosova, Irina (Author) / Kowal, Ewa A. (Author) / Dunn, Matthew R. (Author) / Chaput, John C. (Author) / Van Horn, Wade (Author) / Egli, Martin (Author) / Biodesign Institute (Contributor)
Created2015-12-15
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Description

The single-span membrane protein KCNE3 modulates a variety of voltage-gated ion channels in diverse biological contexts. In epithelial cells, KCNE3 regulates the function of the KCNQ1 potassium ion (K+) channel to enable K+ recycling coupled to transepithelial chloride ion (Cl-) secretion, a physiologically critical cellular transport process in various organs

The single-span membrane protein KCNE3 modulates a variety of voltage-gated ion channels in diverse biological contexts. In epithelial cells, KCNE3 regulates the function of the KCNQ1 potassium ion (K+) channel to enable K+ recycling coupled to transepithelial chloride ion (Cl-) secretion, a physiologically critical cellular transport process in various organs and whose malfunction causes diseases, such as cystic fibrosis (CF), cholera, and pulmonary edema. Structural, computational, biochemical, and electrophysiological studies lead to an atomically explicit integrative structural model of the KCNE3-KCNQ1 complex that explains how KCNE3 induces the constitutive activation of KCNQ1 channel activity, a crucial component in K+ recycling. Central to this mechanism are direct interactions of KCNE3 residues at both ends of its transmembrane domain with residues on the intra- and extracellular ends of the KCNQ1 voltage-sensing domain S4 helix. These interactions appear to stabilize the activated “up” state configuration of S4, a prerequisite for full opening of the KCNQ1 channel gate. In addition, the integrative structural model was used to guide electrophysiological studies that illuminate the molecular basis for how estrogen exacerbates CF lung disease in female patients, a phenomenon known as the “CF gender gap.”

ContributorsKroncke, Brett M. (Author) / Van Horn, Wade (Author) / Smith, Jarrod (Author) / Kang, CongBao (Author) / Welch, Richard C. (Author) / Song, Yuanli (Author) / Nannemann, David P. (Author) / Taylor, Keenan C. (Author) / Sisco, Nicholas J. (Author) / George, Alfred L. (Author) / Meiler, Jens (Author) / Vanoye, Carlos G. (Author) / Sanders, Charles R. (Author) / College of Liberal Arts and Sciences (Contributor)
Created2016-09-09