Vegetative Comparison of Two Gravel Ridge Prairies with Different Grazing Histories in Polk County, Minnesota

The vegetation of a gravel ridge running the length of two native prairie remnants, the Stipa Wildlife Management Area (WMA) and the Tympanuchus WMA, in northwestern Minnesota was compared during June, July, and August 1993. The Stipa WMA was grazed by confined domestic cattle from 1958 to 1977, while the Tympanuchus WMA has been relatively undisturbed. The vegetative composition of each area was compared qualitatively by compiling a plant species list for each ridge. Quantitative vegetative comparisons were conducted by recording abundance and cover values for individual plant species in twenty-five 0.5 m2 random sample plots on each ridge during the first two weeks of August. The calculated Shannon-Wiener diversity index values showed the Tympanuchus WMA ridge vegetation to be more diverse than the Stipa WMA ridge vegetation. Also, 10 plant species predicted to decrease with grazing were found with significantly greater frequency and in higher abundance on the Tympanuchus WMA ridge, while 4 species categorized as weedy invaders under conditions of grazing were found with greater frequency and in higher abundance on the Stipa WMA ridge. Data collected on species expected to increase under heavy grazing pressure, however, were inconclusive. As predicted, the vegetation on the grazed native prairie gravel ridge was less diverse than that on the undisturbed native prairie ridge and consisted of more weedy, introduced plant species and fewer plant species palatable to large grazers

Master of Science

thesisInfant prematurity is associated with acute health risks and altered fat deposition. Aberrations in fat deposition put preterm infants at a higher risk for developing conditions such as hypertension and glucose intolerance in later life. Thus, the recommended catch-up growth for preterm infants, which only examines weight gain, may have detrimental consequences for future metabolic health. Validated, low-risk methods of accurately determining body fat deposition will assist medical professionals in monitoring interventions and optimizing growth quality in preterm infants. This study compared body fat composition in infants that were born preterm (n = 28) between 32-36 weeks postmenstrual age (PMA) and born term (n = 28) between 38-41 weeks PMA at the University of Utah Hospital. Relationships between percent body fat (%BF) measured by air displacement plethysmography (ADP) and anthropometry/skinfolds were determined. Gender and ethnic distribution were similar between the preterm and term cohorts. Age adjusted body weight, length, head circumference, and body mass index were significantly lower for preterm infants (p < 0.001). Despite the smaller body size and less mature PMA at hospital discharge, preterm infants had higher %BF by ADP (p = 0.057). In addition, mid-arm circumference was a good predictor for preterm infant %BF (p < 0.001). Our results show that preterm infants develop increased body fat percentage as they approach term-corrected age compared to term infants. This result may explain the connection between a preterm birth and metabolic consequences later in life. This study provides support for the importance of monitoring body composition in preterm infants to ensure proper growth quality

Uncoupling of p97 ATPase activity has a dominant negative effect on protein extraction

p97 is a highly abundant, homohexameric AAA+ ATPase that performs a variety of essential cellular functions. Characterized as a ubiquitin-selective chaperone, p97 recognizes proteins conjugated to K48-linked polyubiquitin chains and promotes their removal from chromatin and other molecular complexes. Changes in p97 expression or activity are associated with the development of cancer and several related neurodegenerative disorders. Although pathogenic p97 mutations cluster in and around p97's ATPase domains, mutant proteins display normal or elevated ATPase activity. Here, we show that one of the most common p97 mutations (R155C) retains ATPase activity, but is functionally defective. p97-R155C can be recruited to ubiquitinated substrates on chromatin, but is unable to promote substrate removal. As a result, p97-R155C acts as a dominant negative, blocking protein extraction by a similar mechanism to that observed when p97's ATPase activity is inhibited or inactivated. However, unlike ATPase-deficient proteins, p97-R155C consumes excess ATP, which can hinder high-energy processes. Together, our results shed new insight into how pathogenic mutations in p97 alter its cellular function, with implications for understanding the etiology and treatment of p97-associated diseases

Acute nerve stretch and the compound motor action potential

In this paper, the acute changes in the compound motor action potential (CMAP) during mechanical stretch were studied in hamster sciatic nerve and compared to the changes that occur during compression

Age differences in COVID-19 risk-taking, and the relationship with risk attitude and numerical ability

This study aimed to investigate age differences in risk-taking concerning the coronavirus pandemic, while disentangling the contribution of risk attitude, objective risk and numeracy. We tested (i) whether older and younger adults differed in taking coronavirus-related health risks, (ii) whether there are age differences in coronavirus risk, risk attitude and numerical ability and (iii) whether these age differences in coronavirus risk, attitude and numerical ability are related to coronavirus risk-taking. The study was observational, with measures presented to all participants in random order. A sample of 469 participants reported their coronavirus-related risk-taking behaviour, objective risk, risk attitude towards health and safety risks, numerical ability and risk perception. Our findings show that age was significantly related to coronavirus risk-taking, with younger adults taking more risk, and that this was partially mediated by higher numeracy, but not objective risk or risk attitude. Exploratory analyses suggest that risk perception for self and others partially mediated age differences in coronavirus risk-taking. The findings of this study may better our understanding of why age groups differ in their adoption of protective behaviours during a pandemic and contribute to the debate whether age differences in risk-taking occur due to decline in abilities or changes in risk attitude

Risk Factors for African Tick-Bite Fever in Rural Central Africa

African tick-bite fever is an emerging infectious disease caused by the spotted fever group Rickettsia, Rickettsia africae, and is transmitted by ticks of the genus Amblyomma. To determine the seroprevalence of exposure to R. africae and risk factors associated with infection, we conducted a cross-sectional study of persons in seven rural villages in distinct ecological habitats of Cameroon. We examined 903 plasma samples by using an indirect immunofluorescence assay for antibodies to R. africae and analyzed demographic and occupational data collected from questionnaires. Of the 903 persons tested, 243 (26.9%) had IgG/IgM/IgA reactive with R. africae. Persons from four of the seven village sites were significantly more likely to be seropositive (P < 0.05), and lowland forest sites tended to have higher seroprevalences. These results suggest that African tick-bite fever is common in adults in rural areas of Cameroon and that ecological factors may play a role in the acquisition of R. africae infection

Do genetic predictors of pain sensitivity associate with persistent widespread pain?

Genetic risk factors for pain sensitivity may also play a role in susceptibility to chronic pain disorders, in which subjects have low pain thresholds. The aim of this study was to determine if proposed functional single nucleotide polymorphisms (SNPs) in the GTP cyclohydrolase (GCH1) and μ opioid receptor (OPRM1) genes previously associated with pain sensitivity affect susceptibility to chronic widespread pain (CWP). Pain data was collected using body manikins via questionnaire at three time-points over a four year period from subjects aged 25-65 in the North-West of England as part of a population based cohort study, EPIFUND. CWP was defined at each time point using standard criteria. Three SNPs forming a proposed "pain-protective" haplotype in GCH1 (rs10483639, rs3783641 and rs8007267) and two SNPs in OPRM1 (rs1777971 (A118G) and rs563649) were genotyped in cases with persistent CWP (CWP present at ≥2 time-points) and controls who were pain-free at all time-points. The expectation-maximisation algorithm was used to estimate haplotype frequencies. The frequency of the "pain-protective" (CAT - C allele of rs10483639, A allele of rs3783641 and T allele of rs8007267) haplotype was compared to the frequency of the other haplotypes between cases and controls using the χ2 test. Allele frequencies and carriage of the minor allele was compared between cases and controls using χ2 tests for the OPRM1 SNPs. The frequency of the proposed GCH1 "pain-protective" haplotype (CAT) did not significantly differ between cases and controls and no significant associations were observed between the OPRM1 SNPs and CWP. In conclusion, there was no evidence of association between proposed functional SNPs, previously reported to influence pain sensitivity, in GCH1 and OPRM1 with CWP. Further evidence of null association in large independent cohorts is required to truly exclude these SNPs as genetic risk factors for CWP

Jurisdiction Over Endangered Species' Habitat: the Impacts of People and Property on Recovery Planning

Coordinating management among multiple landowners and jurisdictional agencies is one of the greatest challenges confronting conservation planning. In this study, we assessed the impacts on recovery progress of the people and property involved in recovery plan development and implementation. We compared indices of recovery progress among endangered species whose primary habitat falls into one of four federal jurisdiction categories: nonfederal land only, 50% but not all federal land, and all federal land. Species found exclusively on federal land are more likely to be improving in status. This may result from the fact that overall implementation of recovery tasks is lower among species occurring exclusively on nonfederal lands. Revision status, the existence of a centralized database, the designation of a person or committee to coordinate plan implementation, the parties involved in drafting the plan, and those designated as responsible for implementing recovery tasks are also significant factors in determining recovery plan implementation. Specifically, diversity of recovery team membership and the average number of participants increase with increasing federal jurisdiction, and tasks are more likely to be completed when more parties are involved in developing recovery plans. However, fewer recovery tasks are completed as the number of parties involved in implementation increases, suggesting that species on federal lands may benefit from less division of labor among agencies. Differences in drafting plans and administering their implementation appear to be stronger determinants of the observed variation in recovery success than differences in the kinds of threats facing species and their habitats

Distinct Clinical and Pathological Features Are Associated with the BRAFT1799A(V600E) Mutation in Primary Melanoma

The BRAFT1799A mutation encodes BRAFV600E that leads to activation of the mitogen-activated protein kinase pathway. This study aimed to assess the clinico-pathological features of primary invasive melanomas containing the BRAFT1799A mutation. Patients (n=251) with invasive primary melanomas from Australia were interviewed and examined with respect to their melanoma characteristics and risk factors. Independent review of pathology, allele-specific PCR for the BRAFT1799A mutation, immunohistochemical staining with Ki67, and phospho-histone-H3 (PH3) were performed. The BRAFT1799A mutation was found in 112 (45%) of the primary melanomas. Associations with the BRAFT1799A mutation (P<0.05) were as follows: low tumor thickness (odds ratio (OR)=3.3); low mitotic rate (OR=2.0); low Ki67 score (OR=5.0); low PH3 score (OR=3.3); superficial spreading melanoma (OR=10.0); pigmented melanoma (OR=3.7); a lack of history of solar keratoses (OR=2.7); a location on the trunk (OR=3.4) or extremity (OR=2.0); a high level of self-reported childhood sun exposure (OR=2.0); ≤50 years of age (OR=2.5); and fewer freckles (OR=2.5). We conclude that the BRAFT1799A mutation has associations with host phenotype, tumor location, and pigmentation. Although implicated in the control of the cell cycle, the BRAFT1799A mutation is associated with a lower rate of tumor proliferation