Magnetic properties of a diferrous-water complex and ligands for modeling the active site of MMOH

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2004.Vita.Includes bibliographical references.Chapter 1: The Importance of Modeling Diiron Sites in Nature.There are a variety of metalloenzymes that have nearly identical carboxylate-bridged diiron active sites. An example is sMMOH, an enzyme that catalyzes the conversion of methane to methanol. A detailed description of the active site of sMMOH[red] is given and attempts at reproducing its structure in a model complex are discussed. Chapter 2: A Diiron(II) Diaqua Complex: Modeling Water in the Active Site of sMMOH[red]. There are water molecules in the first and second coordination spheres of the diiron centers in sMMOH[red]. A carboxylate-bridged diferrous complex, [Fe₂...(THF)₂], was synthesized to incorporate the presence of water in a model complex and to investigate the function(s) of these water molecules. The synthesis, structural characterization and magnetic properties of this complex are presented. Chapter 3: Ligands for Modeling the Syn Disposition of Nitrogen Atoms in the Active Site of MMOH. The active sites of a variety of carboxylate-bridged diiron metalloenzymes are very similar and feature the syn disposition of two histidine ligands with respect to the iron-iron vector. This orientation has not yet been modeled in a diiron complex with four carboxylate ligands and a stable yet flexible platform. Such geometry may be necessary to replicate the functions of these enzymes. The syntheses of ligands intended to enforce this syn disposition are described and directions for future ligand design are outlined.by Amy E. Kelly.S.M

Hydrocarbon biomarkers for biotic and environmental evolution through the Neoproterozoic-Cambrian transition

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2009.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references.The sequence of events over the Neoproterozoic - Cambrian transition that led to the radiation of multicellular organisms has been an issue of debate for over a century. It is a critical interval in the history of life on Earth because it marks the first appearance of all extant animal phyla in the fossil record. We set out to improve understanding of environmental transitions during this key interval of Earth's history by studying chemical fossils (biomarkers) in Neoproterozoic to Cambrian aged sedimentary rocks and oils from Australia, Eastern Siberia and Oman. This thesis presents the distributions of steranes and other hydrocarbons through these various strata and the characterization of novel age and paleostratification biomarkers. Compound specific carbon isotopic data of n-alkanes and isoprenoids were also acquired and evaluated in the context of existing datasets with a focus on elucidating the processes responsible for anomalous trends. Consistent with current theory, our results indicate that there was a significant shift in the redox state the oceans and that this took place on a global scale. The biomarker and isotopic proxies we have measured help us further constrain the timing of this redox shift, and suggest a concomitant switch in the composition of marine photosynthetic communities, at termination of the Neoproterozoic Era.by Amy Elizabeth Kelly.Ph.D

Medication adherence in patients with myotonic dystrophy and facioscapulohumeral muscular dystrophy

Myotonic dystrophy (DM) and facioscapulohumeral muscular dystrophy (FSHD) are the two most common adult muscular dystrophies and have progressive and often disabling manifestations. Higher levels of medication adherence lead to better health outcomes, especially important to patients with DM and FSHD because of their multisystem manifestations and complexity of care. However, medication adherence has not previously been studied in a large cohort of DM type 1 (DM1), DM type 2 (DM2), and FSHD patients. The purpose of our study was to survey medication adherence and disease manifestations in patients enrolled in the NIH-supported National DM and FSHD Registry. The study was completed by 110 DM1, 49 DM2, and 193 FSHD patients. Notable comorbidities were hypertension in FSHD (44 %) and DM2 (37 %), gastroesophageal reflux disease in DM1 (24 %) and DM2 (31 %) and arrhythmias (29 %) and thyroid disease (20 %) in DM1. Each group reported high levels of adherence based on regimen complexity, medication costs, health literacy, side effect profile, and their beliefs about treatment. Only dysphagia in DM1 was reported to significantly impact medication adherence. Approximately 35 % of study patients reported polypharmacy (taking 6 or more medications). Of the patients with polypharmacy, the DM1 cohort was significantly younger (mean 55.0 years) compared to DM2 (59.0 years) and FSHD (63.2 years), and had shorter disease duration (mean 26 years) compared to FSHD (26.8 years) and DM2 (34.8 years). Future research is needed to assess techniques to ease pill swallowing in DM1 and to monitor polypharmacy and potential drug interactions in DM and FSHD

Self-reported Barriers to Treatment Engagement: Adolescent Perspectives from the National Comorbidity Survey-Adolescent Supplement (NCS-A)

The objective of this study was to assess youth self-reported treatment barriers in the past 12 months to obtain youth’s perspective on reasons they seek treatment, do not engage in treatment, or terminate treatment. The present study uses data from the National Comorbidity Survey-Adolescent Supplement (NCS-A), a nationally representative survey administered to youth ages 13–18 that was conducted between February 1, 2001 and January 30, 2004. A total of 10,123 youth participated in the NCS-A study and provided the information on which the current paper draws its data. Within the past 12 months over 63 % of youth reported seeking treatment to manage and cope with emotions. The greatest percentage of youth reported that they did not seek treatment because they wanted to handle the problem on their own (59.3 %). The greatest percentage of youth reported that treatment was terminated because they wanted to handle the problem on their own (57.5 %). Findings suggest professionals need to educate youth about the importance of professional treatment to increase engagement. If providers can motivate youth to see the value of treatment and help them understand that there can be positive outcomes, they may be less likely to terminate prematurely

Sexual Harassment Experiences and Harmful Alcohol Use in a Military Sample: Differences in Gender and the Mediating Role of Depression

The current investigation identified the genderspecific prevalence of sexual harassment and assault experienced during U.S. military service and the negative mental and physical health correlates of these experiences in a sample of former reservists. We surveyed a stratified random sample of 3,946 former reservists about their experiences during military service and their current health, including depression, posttraumatic stress disorder, somatic symptoms, and medical conditions. Prevalence estimates and confidence intervals of sexual harassment and assault were calculated. A series of logistic regressions identified associations with health symptoms and conditions. Both men and women had a substantial prevalence of military sexual harassment and assault. As expected, higher proportions of female reservists reported sexual harassment (60.0% vs 27.2% for males) and sexual assault (13.1% vs 1.6% for males). For both men and women, these experiences were associated with deleterious mental and physical health conditions, with sexual assault demonstrating stronger associations than other types of sexual harassment in most cases. This investigation is the first to document high instances of these experiences among reservists. These data provide further evidence that experiences of sexual harassment and assault during military service have significant implications for the healthcare needs of military veterans

Promoting Literacy in a Virtual World: Success Stories of Two University Student Clubs

The Student Education Association and Kappa Delta Pi at Governors State University has a main goal this semester, which is to promote literacy in a virtual world. The purpose of this is to help all young individuals become strong readers. Our organization was fortunate enough to receive a grant from the National Education Association (NEA) that allowed us to purchase children’s books, invite guest speakers, and create workshops about varying social issues. This was in collaboration with a local library. Some of the social issues that were highlighted in our workshops are community and activism, women’s rights, and identity. We will also be hosting workshops about animals and the environment in April. Each library workshop had a guest speaker that read the book to all the students and their families. In addition to that, our SEA leaders facilitated activities that helped engage the students with the content of the book. Along with the library workshops, SEA and KDP leaders as well as faculty advisors have been hosting virtual read alouds live on our Facebook page each month. Each month had a selection of 9- 11 books about a specific topic. Starting in February and in honor of Black History Month, leaders and advisors read books about African- American figures. In March, two sets of virtual read alouds were read to the students. Throughout the whole month, leaders and advisors have been reading books about women leaders in honor of Women\u27s History Month. In addition to that, 11 read alouds were hosted on March 2nd in honor of National Read Across America Day. In April, our read- alouds theme will be about animals and the environment

Whole genome sequencing-based mapping and candidate identification of mutations from fixed zebrafish tissue

As forward genetic screens in zebrafish become more common, the number of mutants that cannot be identified by gross morphology or through transgenic approaches, such as many nervous system defects, has also increased. Screening for these difficult-to-visualize phenotypes demands techniques such as whole-mount in situ hybridization (WISH) or antibody staining, which require tissue fixation. To date, fixed tissue has not been amenable for generating libraries for whole genome sequencing (WGS). Here, we describe a method for using genomic DNA from fixed tissue and a bioinformatics suite for WGS-based mapping of zebrafish mutants. We tested our protocol using two known zebrafish mutant alleles, gpr126st49 and egr2bfh227, both of which cause myelin defects. As further proof of concept we mapped a novel mutation, stl64, identified in a zebrafish WISH screen for myelination defects. We linked stl64 to chromosome 1 and identified a candidate nonsense mutation in the F-box and WD repeat domain containing 7 (fbxw7) gene. Importantly, stl64 mutants phenocopy previously described fbxw7vu56 mutants, and knockdown of fbxw7 in wild-type animals produced similar defects, demonstrating that stl64 disrupts fbxw7. Together, these data show that our mapping protocol can map and identify causative lesions in mutant screens that require tissue fixation for phenotypic analysis

Detection and persistence of environmental DNA from an invasive, terrestrial mammal

Invasive Sus scrofa, a species commonly referred to as wild pig or feral swine, is a destructive invasive species with a rapidly expanding distribution across the United States. We used artificial wallows and small waterers to determine the minimum amount of time needed for pig eDNA to accumulate in the water source to a detectable level. We removed water from the artificial wallows and tested eDNA detection over the course of 2 weeks to understand eDNA persistence. We show that our method is sensitive enough to detect very low quantities of eDNA shed by a terrestrial mammal that has limited interaction with water. Our experiments suggest that the number of individuals shedding into a water system can affect persistence of eDNA. Use of an eDNA detection technique can benefit management efforts by providing a sensitive method for finding even small numbers of individuals that may be elusive using other methods

Accounting for observation processes across multiple levels of uncertainty improves inference of species distributions and guides adaptive sampling of environmental DNA

Understanding factors that influence observation processes is critical for accurate assessment of underlying ecological processes. When indirect methods of detection, such as environmental DNA, are used to determine species presence, additional levels of uncertainty from observation processes need to be accounted for. We conducted a field trial to evaluate observation processes of a terrestrial invasive species (wild pigs‐ Sus scrofa) from DNA in water bodies. We used a multi‐scale occupancy analysis to estimate different levels of observation processes (detection, p): the probability DNA is available per sample (θ), the probability of capturing DNA per extraction (γ), and the probability of amplification per qPCR run (δ). We selected four sites for each of three water body types and collected 10 samples per water body during two months (September and October 2016) in central Texas. Our methodology can be used to guide sampling adaptively to minimize costs while improving inference of species distributions. Using a removal sampling approach was more efficient than pooling samples and was unbiased. Availability of DNA varied by month, was considerably higher when water pH was near neutral, and was higher in ephemeral streams relative to wildlife guzzlers and ponds. To achieve a cumulative detection probability \u3e90% (including availability, capture, and amplification), future studies should collect 20 water samples per site, conduct at least two extractions per sample, and conduct five qPCR replicates per extraction. Accounting for multiple levels of uncertainty of observation processes improved estimation of the ecological processes and provided guidance for future sampling designs

Postnatal β2 adrenergic treatment improves insulin sensitivity in lambs with IUGR but not persistent defects in pancreatic islets or skeletal muscle

Placental insufficiency causes intrauterine growth restriction (IUGR) and disturbances in glucose homeostasis with associated β adrenergic receptor (ADRβ) desensitization. Our objectives were to measure insulin-sensitive glucose metabolism in neonatal lambs with IUGR and to determine whether daily treatment with ADRβ2 agonist and ADRβ1/β3 antagonists for 1 month normalizes their glucose metabolism. Growth, glucose-stimulated insulin secretion (GSIS) and glucose utilization rates (GURs) were measured in control lambs, IUGR lambs and IUGR lambs treated with adrenergic receptor modifiers: clenbuterol atenolol and SR59230A (IUGR-AR). In IUGR lambs, islet insulin content and GSIS were less than in controls; however, insulin sensitivity and whole-bodyGUR were not different from controls.Of importance, ADRβ2 stimulation with β1/β3 inhibition increases both insulin sensitivity and whole-body glucose utilization in IUGR lambs. In IUGR and IUGR-AR lambs, hindlimb GURs were greater but fractional glucose oxidation rates and ex vivo skeletal muscle glucose oxidation rates were lower than controls. Glucose transporter 4 (GLUT4) was lower in IUGR and IUGR-AR skeletal muscle than in controls but GLUT1 was greater in IUGR-AR. ADRβ2, insulin receptor, glycogen content and citrate synthase activity were similar among groups. In IUGR and IUGR-AR lambs heart rates were greater, which was independent of cardiac ADRβ1 activation. We conclude that targeted ADRβ2 stimulation improved whole-body insulin sensitivity but minimally affected defects in GSIS and skeletal muscle glucose oxidation. We show that risk factors for developing diabetes are independent of postnatal catch-up growth in IUGR lambs as early as 1 month of age and are inherent to the islets and myocytes