Learning from taste: Brain connectivity, adaptation, and behavioral correlates

Food choices are the foundation of eating habits and contribute to weight status and health. Food choices are informed by expectations about a food’s reward value learned through appetitive food conditioning. This dissertation investigated brain connectivity during conditioning via food reward and punishment and brain adaptation to repeated exposure to food cue and tastes. An overarching goal was to identify how individual differences in behavioral characteristics relate to brain response and learning outcomes. Data from healthy, young adults (n=90) characterized brain network structure during completion of a response-dependent, taste motivated instrumental conditioning task, called the appetitive Probabilistic Selection Task (PST). We examined behavioral, psychological, and physiological correlates of learning outcomes measured by the PST. During the PST, brain networks organization was similar across conditions in the task (choice, sweet/bitter taste), with key differences in connectivity of prefrontal regions between sweet and bitter tastes. During choice, increased within-network connectivity of a network containing memory and learning regions correlated with increased behavioral sensitivity to food punishment. Negative correlates of learning included external eating and body mass index (BMI) and in women, trait sensitivity to punishment was positively associated with behavioral sensitivity to food reward and punishment. Data from healthy adolescents (n=154) examined how brain response to food cue/taste adapted with repeated exposure. Response in motivation and attention regions increased following repeated cue presentations, and response in taste responsiveness areas increased following repeated taste administration. Additionally, individual differences in the magnitude of change was correlated with age/sex adjusted BMI. Together, results identify individual differences in brain response and behavioral outcomes of food conditioning. Findings suggest high BMI and high susceptibility to cued-overeating are related to decreased ability to make choices based on food’s motivational value, and that higher BMI is associated with greater attention/motivation for food cues with repeated exposure. Together, these outcomes place individuals at elevated risk of making misinformed food decisions and misallocating effort to attain food reward. Identifying individual differences in food conditioning can better predict eating behavior and obesity risk in healthy populations and support eating behavior interventions focused on decreasing food cue-responsiveness and increasing eating outcomes sensitivity.Doctor of Philosoph

“This doesn’t feel like living”: How the COVID-19 Pandemic Affected the Mental Health of Vulnerable University Students in the United Kingdom

Introduction: Concerns about student mental health have been rising globally. The COVID-19 pandemic triggered unprecedented disruption in higher education as universities were forced to close and adapt their education delivery. Understanding the impact of this on vulnerable students can inform higher education’s response to future similar events. Aims: To understand the lived experience of first year university students studying in the United Kingdom, who had a history of poor mental health and lived on a low income, we examined the inter-relatedness between mental health, financial strain, remote learning and engagement, and well-being. Methods: At the start of their first year of study, whilst the UK was in periods of lockdown, we conducted in-depth semi-structured interviews with 20 diverse first-year university students. We analyzed data using interpretative phenomenological analysis. Results: The pandemic’s impact on student mental health, engagement and learning remained pervasive and serious. Key themes conveyed how isolation triggered past mental health difficulties and a perception that the universities – and government – had forgotten about them. Students also experienced greater difficulty in navigating the liminal threshold between being a child and an adult, and having the additional worry of financial instability left students with fewer coping resources. Conclusions: To mitigate the impact of future pandemic responses, constant and effective communication is needed between faculty and students to safeguard against isolation and low motivation. Vulnerable students need guidance in coping skills to manage mental health risks when they are away from family and familiar support network

Watershed Management on Range and Forest Lands Proceedings of the Fifth Workshop of the United States/Australia Rangelands Panel

Preface: The U.S.-Australia Cooperative Rangeland Science Program In October 1968 the governments of the United States and Australia entered into an agreement for the purpose of facilitating close cooperative activities between the scientific communities of the two countries. The joint communique issued at that time designated the U.S. National Science Foundation and the Australian Commonwealth Department of Education and Science as the coordinating agencies. Both countries were to encourage binational teamwork in research, interchanges of scientists, joint seminars, and exchanges of information. A United States-Australia Rangeland Panel was established in December 1969 to further cooperation between the two countries in the rangeland sciences. The present panel includes the following

Human APOBEC3G-mediated hypermutation is associated with antiretroviral therapy failure in HIV-1 subtype C-infected individuals

Introduction: Human APOBEC3G/F (hA3G/F) restricts retroviral replication through G-to-A hypermutations, which can generate drug-resistant progenies in vitro. The clinical relevance is still inconclusive. To bridge this gap, we aim to study the role of these hypermutations in evolution of drug resistance; we characterised hA3G/F-mediated hypermutations in the RT region of the pol gene of patients with or without antiretroviral therapy (ART). Methods: In 88 HIV-1-positive individuals, drug resistance genotyping was carried out in plasma virus and provirus by population sequencing. Hypermutations were determined by three different approaches using Hypermut 2.0 software, cluster analysis and APOBEC3G-mediated defectives indices. Clinical and demographic characteristics of these individuals were studied in relation to these hypermutations. Results: hA3G/F-mediated hypermutated sequences in proviral DNA, but not in plasma virus, were identified in 11.4% (10/88) subjects. Proviral hypermutations were observed more frequently in patients with ART failure than in ART-naïve individuals (p=0.03). In therapy failure patients, proviral hypermutation were associated with greater intra-compartmental genetic diversity (p<0.001). In therapy-naïve individuals, hypermutated proviral DNA with M184I and M230I mutations due to the editing of hA3G, had stop codons in the open reading frames and the same mutations were absent in the plasma virus. Only a limited concordance was found between the drug resistance mutations in plasma RNA and proviral DNA. Conclusions: hA3G lethal hypermutation was significantly associated with ART failure in Indian HIV-1 subtype C patients. It is unlikely that viral variants, which exhibit hypermutated sequences and M184I and/or M230I, will mature and expand in vivo

The N-glycan processing enzymes α-mannosidase and β-D-N-acetylhexosaminidase are involved in ripening-associated softening in the non-climacteric fruits of capsicum

Excessive softening of fruits during the ripening process leads to deterioration. This is of significant global importance as softening-mediated deterioration leads to huge postharvest losses. N-glycan processing enzymes are reported to play an important role during climacteric fruit softening: however, to date these enzymes have not been characterized in non-climacteric fruit. Two ripening-specific N-glycan processing enzymes, α-mannosidase (α-Man) and β-D-N-acetylhexosaminidase (β-Hex), have been identified and targeted to enhance the shelf life in non-climacteric fruits such as capsicum (Capsicum annuum). The purification, cloning, and functional characterization of α-Man and β-Hex from capsicum, which belong to glycosyl hydrolase (GH) families 38 and 20, respectively, are described here. α-Man and β-Hex are cell wall glycoproteins that are able to cleave terminal α-mannose and β-D-N-acetylglucosamine residues of N-glycans, respectively. α-Man and β-Hex transcripts as well as enzyme activity increase with the ripening and/or softening of capsicum. The function of α-Man and β-Hex in capsicum softening is investigated through RNA interference (RNAi) in fruits. α-Man and β-Hex RNAi fruits were approximately two times firmer compared with the control and fruit deterioration was delayed by approximately 7 d. It is shown that silencing of α-Man and β-Hex enhances fruit shelf life due to the reduced degradation of N-glycoproteins which resulted in delayed softening. Altogether, the results provide evidence for the involvement of N-glycan processing in non-climacteric fruit softening. In conclusion, genetic engineering of N-glycan processing can be a common strategy in both climacteric and non-climacteric species to reduce the post-harvest crop losses

Snowball Earth climate dynamics and Cryogenian geology-geobiology

Geological evidence indicates that grounded ice sheets reached sea level at all latitudes during two long-lived Cryogenian (58 and ≥5 My) glaciations. Combined uranium-lead and rhenium-osmium dating suggests that the older (Sturtian) glacial onset and both terminations were globally synchronous. Geochemical data imply that CO2 was 102 PAL (present atmospheric level) at the younger termination, consistent with a global ice cover. Sturtian glaciation followed breakup of a tropical supercontinent, and its onset coincided with the equatorial emplacement of a large igneous province. Modeling shows that the small thermal inertia of a globally frozen surface reverses the annual mean tropical atmospheric circulation, producing an equatorial desert and net snow and frost accumulation elsewhere. Oceanic ice thickens, forming a sea glacier that flows gravitationally toward the equator, sustained by the hydrologic cycle and by basal freezing and melting. Tropical ice sheets flow faster as CO2 rises but lose mass and become sensitive to orbital changes. Equatorial dust accumulation engenders supraglacial oligotrophic meltwater ecosystems, favorable for cyanobacteria and certain eukaryotes. Meltwater flushing through cracks enables organic burial and submarine deposition of airborne volcanic ash. The subglacial ocean is turbulent and well mixed, in response to geothermal heating and heat loss through the ice cover, increasing with latitude. Terminal carbonate deposits, unique to Cryogenian glaciations, are products of intense weathering and ocean stratification. Whole-ocean warming and collapsing peripheral bulges allow marine coastal flooding to continue long after ice-sheet disappearance. The evolutionary legacy of Snowball Earth is perceptible in fossils and living organisms

Exploring the lived experience of gay men with prostate cancer: A phenomenological study

Purpose: Gay men with prostate cancer are an ‘invisible species’ in the research literature despite concerns that the impact of treatment may be more profound and in some ways unique compared to heterosexual men. The aim of this research is to explore the lived experience of gay men with prostate cancer. Method: In-depth interviews were recorded and transcribed verbatim from a purposive sample of eight gay men treated for prostate cancer in Ireland. A qualitative methodological approach employing Giorgi's descriptive phenomenological method was used to collect and analyse data. Findings: Three key aspects emerged representing the essence of the participants lived experience; The experience of diagnosis, treatment decision making, and the impact of treatment, with sub-themes of shock of diagnosis, the generalist nature of information, sexual side effects and incontinence, and masculinity and gay identity. Secondly, the experience of the healthcare service with sub-themes of sexual orientation disclosure and communication with the healthcare team; and thirdly, sources of support and means of coping which included significant others, family & friends, cancer support groups, and gay resources and support services. Conclusion: Gay men with prostate cancer have unmet information and supportive care needs throughout their prostate cancer journey, especially related to the impact of sexual dysfunction and associated rehabilitation, negatively impacting their quality of life. Issues associated with heteronormativity, minority stress, and stigma may influence how gay men interact with the health service, or how they perceive the delivery of care. Healthcare education providers should update prostate cancer education programmes accordingly

A Large-Scale Distribution of Milk-Based Fortified Spreads: Evidence for a New Approach in Regions with High Burden of Acute Malnutrition

BACKGROUND: There are 146 million underweight children in the developing world, which contribute to up to half of the world's child deaths. In high burden regions for malnutrition, the treatment of individual children is limited by available resources. Here, we evaluate a large-scale distribution of a nutritional supplement on the prevention of wasting. METHODS AND FINDINGS: A new ready-to-use food (RUF) was developed as a diet supplement for children under three. The intervention consisted of six monthly distributions of RUF during the 2007 hunger gap in a district of Maradi region, Niger, for approximately 60,000 children (length: 60-85 cm). At each distribution, all children over 65 cm had their Mid-Upper Arm Circumference (MUAC) recorded. Admission trends for severe wasting (WFH<70% NCHS) in Maradi, 2002-2005 show an increase every year during the hunger gap. In contrast, in 2007, throughout the period of the distribution, the incidence of severe acute malnutrition (MUAC<110 mm) remained at extremely low levels. Comparison of year-over-year admissions to the therapeutic feeding program shows that the 2007 blanket distribution had essentially the same flattening effect on the seasonal rise in admissions as the 2006 individualized treatment of almost 60,000 children moderately wasted. CONCLUSIONS: These results demonstrate the potential for distribution of fortified spreads to reduce the incidence of severe wasting in large population of children 6-36 months of age. Although further information is needed on the cost-effectiveness of such distributions, these results highlight the importance of re-evaluating current nutritional strategies and international recommendations for high burden areas of childhood malnutrition