Motivation Matters: Understanding the Antidepressant Mechanism of Physical Activity among Young Adults

International Journal of Exercise Science 17(5): 861-873, 2024. A negative association between physical activity and depressive symptoms is consistently reported within scientific literature and physical self-concept has been suggested to mediate this pathway. However, for whom these associations are strongest remains poorly understood, and little is known about how other psychosocial factors might be implicated. Consequently, we examined how various exercise motivations, specifically appearance, physical health, and mental health, might moderate the indirect effect of physical activity on depressive symptoms through physical self-concept. Canadian young adults (N = 496, Mage = 20.36, SD = 1.87) completed an online questionnaire. Mediation and moderated-mediation models were tested using PROCESS macro in RStudio. A significant indirect effect (ß = -0.18, CI [-0.005, -0.003]) of physical activity on depressive symptoms through physical self-concept was found. Exercise motivations moderated the association between physical activity and physical self-concept, such that the association was stronger when individuals were motivated by physical health. Thus, the effect of physical activity on depressive symptoms varied according to physical self-concept and physical health-exercise motivations. We conclude that motivation should be considered when developing and delivering physical activity prevention efforts for depressive symptoms

Parental Anxiety Associated with Summer Camp Experiences: A Comparative Analysis Across Volunteer and Employee-Staffed Camps

Parent anxiety can limit a parent’s willingness to involve their child in out-of-school time experiences such as summer camps. Researchers have studied anxiety within the context of camp, but these studies used narrow frameworks of anxiety. In this exploratory study, we collected open-ended responses about causes of parent anxiety associated with summer camp experiences from 656 parents whose children attended one of two Extension-administered camps. The camps represented different camp staffing models—one primarily staffed by volunteers and the other primarily staffed by employees. The primary purpose of the study was to identify salient categories of anxiety and to examine if anxiety differed based on staffing model. The secondary purpose was to develop a camp-related parent anxiety measure informed by the anxiety categories. Eleven categories were constructed from the data, which both affirmed and expanded existing literature on parent anxiety associated with camp experiences. No differences in parent anxiety were found based on staffing model, suggesting that parents were no more likely to perceive anxiety associated with camp when the program was staffed with volunteers as they were when the program was staffed by employees. Implications for practice and future directions are examined

Amelioration of root disease of subterranean clover (Trifolium subterraneum) by mineral nutrients

Subterranean clover (Trifolium subterraneum) is a key pasture legume across southern Australia and elsewhere. Decline in subterranean clover pastures was first recognised in Australia during the 1960s and manifests as an increase in weeds and a decrease in desirable legume species. While both root disease and poor nutrition contribute to subterranean clover pasture decline, the relationships between root disease and nutrition have not been determined. The objective of this study was to define these relationships. Field experiments were undertaken to determine the nutritional and pathogen status of soils and subterranean clover from three Western Australian field sites. Subsequently, controlled environment experiments were undertaken to determine the relative severities of tap and lateral root disease and growth of plants when soil cores taken from these three field sites were amended with a complete nutrient solution or a range of individual macro- or micronutrient treatments. Application of a ‘Hoaglands’ complete nutrient solution decreased the severity of tap root disease by an average of 45% and lateral root disease by 32%. Amendment with K alone reduced the severity of tap root disease an average of 32%; while the application of N alone reduced the severity of tap root disease by 33% and lateral root disease by 27%. Application of Hoaglands, K, N or Zn increased shoot and root dry weight, while Mo only increased shoot dry weight. This is the first report to show that mineral nutrients can substantially ameliorate root disease in subterranean clover. The results demonstrate that while root disease limits plant growth, improvement in the nutritional status of nutrient-impoverished soils can significantly reduce root disease. There is significant potential to incorporate nutrient amendments into an integrated and more sustainable approach to better manage root disease and to increase productivity of pasture legumes where soils are inherently nutrient deficient in one or more nutrients

Nutrient Recovery Via Anaerobic Digestion Of Supermarket Food Waste And Re-Use As Fertiliser In Potting Media For The Urban Retail Market; A Proof Of Concept Using Digestate And Biochar

Food waste can be diverted from landfill and utilised via anaerobic digestion (AD) to produce biogas. The liquid by-product of AD is commonly referred to as digestate, and this can be an organic certifiable biofertilizer. Digestate in Europe is frequently used in agriculture, though is not commonly used in the urban retail market. Biochar is another organic matter which can adsorb and retain the nutrients, and also could decrease the adverse effects of high nitrogen content of soil

Improving the Phosphorus Efficiency of Temperate Australian Pastures

Phosphorus (P) is a key input necessary for high production in many temperate, grass-legume pasture systems in Australia because the pastures are situated on P-deficient and moderate to highly P-sorbing soils. A consequence of P-sorption in these soils is that much more P must be applied as fertiliser than will be exported in animal products. The P balance efficiency (PBE=100*Pexport/Pinputs) of grazing enterprises (e.g. wool, meat, milk and live animal export) is about 10-30% and compares poorly with some other agricultural enterprises (e.g. 45-54% for grain production; McLaughlin et al. 1992; Weaver and Wong 2011). P accumulates in these soils when they are fertilised as a result of phosphate reactions with Ca and/or Al and Fe oxides, and P incorporation into resistant organic materials (McLaughlin et al. 2011). Some P in grazed fields is also accumulated in animal camps. The net rate of P accumulation in soil (and in grazed fields as a whole) is related to the concentration of plant-available P in the soil. Operating grazing systems at lower plant-available P levels should help to slow P accumulation and result in more effective use of P fertiliser (Simpson et al. 2010; Simpson et al. 2011). Because the P requirement of grass-legume pastures is usually set by the high P requirements of the legume (Hill et al. 2005), we commenced a study to quantify the P requirements of a range of legumes to determine whether productive, lower P-input grazing systems can be developed. We are also screening subterranean clover, the most widely used pasture legume in temperate Australia, for root traits related to P efficiency. Here we report early findings from the establishment year of a field experiment to determine the P requirement of several alternative temperate legumes

Autophagy, but Not Proteolysis, May Aid in Muscle Protein Synthesis

For muscle growth to occur, protein synthesis must be greater than protein degradation. However, up to this point, anabolic pathways have garnered the brunt of investigations examining anabolic capacity with little investigation into the connectedness of catabolic signaling on these anabolic targets. PURPOSE: The purpose of this study was to elucidate the contributions of proteasomal-dependent and autophagic-dependent catabolic pathways on anabolism via analysis of fractional synthetic rates (FSR) in L6 myotubes. METHODS: Differentiated, cultured L6 myoblasts were treated with media containing 4% deuterium oxide (stable isotope label) and a corresponding pharmacological treatment (NSC 185058 [autophagic inhibitor; 100 μM], MG-262 [proteasomal inhibitor; 0.01 μM] or DMSO control; n=3/group) during the final 24-hours of the differentiation period prior to harvest. The myofibrillar pellet of the processed samples was used to determine FSR via mass-spectrometry analysis. DMSO-treated myotubes served as controls, with a one-way analysis of variance and Tukey’s post-hoc test used to test for any differences among groups. RESULTS: Our results indicate that MG-262 had no impact on myofibrillar FSR when compared to DMSO control (MG-262 1.0993 %/day vs. control 1.239 %/day). However, NSC 185058 lowered myofibrillar FSR (NSC 185058 0.9009 %/day vs. control 1.239 %/day; P=0.0282). CONCLUSION: These data suggest that inhibition of autophagic machinery can impair anabolism. This may be due to autophagy’s role in increasing the amino acid pool within the cell. Further, the lack of inhibition seen from MG-262 suggests that there is a delineation of roles within the catabolic pathways in regard to their influence on anabolism in healthy, metabolically unchallenged myotubes

The where, when and what of phosphorus fertilisation for seedling establishment in a biodiverse jarrah forest restoration after bauxite mining in Western Australia

Fertiliser application to restore nutrients lost in the mining process and facilitate early plant establishment and growth is a key step in the restoration of sites disturbed by mining. However, few studies have investigated the effects of different fertiliser types and application methods on mine restoration outcomes, especially in highly biodiverse ecosystems such as the jarrah forest. This forest is a unique, floristically diverse landscape with species adapted to growth on highly weathered phosphorus impoverished Ferralsol. In this study we investigated the effect of fertiliser type (rock phosphate, single superphosphate, and an NPK fertiliser), application method (top-dressed versus incorporated), and the timing of application (winter vs. summer) on the trajectory of jarrah (Eucalyptus marginata) forest restoration following bauxite mining compared to an unfertilised control. All fertilised soil had elevated Colwell-P concentrations (bar rock phosphate) and had considerably less N than found in the native forest, even after N fertilisation. Fertiliser incorporation resulted in a more even distribution of P down the soil profile and increased overall plant growth (as assessed by percentage cover) compared with either top-dressed fertiliser application and no fertiliser, potentially offering better erosion control. In contrast, native species richness was highest in the zero fertiliser and NPK treatments and lowest in the phosphorus incorporation treatments. On average, unfertilised plots had 10 more native species per plot than those fertilised with P only. Fertiliser application also reduced the abundance and cover of Bossiaea ornata and Lomandra spp., both of which are small slow-growing understorey taxa. In contrast, the legume Acacia celastrifolia exhibited a vigorous growth response to fertiliser, with growth being greatest when P (either rock phosphate or SSP) was incorporated. These data suggest that P fertiliser incorporation is a potential strategy to both maximise early plant growth and cover and increase the efficiency of P application. However, if the goal of restoration is to maximise diversity then moderation in P application and using fertilisers that also contain N and K may be appropriate

Insulin-induced Increase in Anabolic Capacity is Blunted by Autophagic Inhibition in L6 Myotubes

Insulin is an anabolic hormone that acts on skeletal muscle cells to stimulate protein synthesis, an effect that is enhanced by the availability of amino acids. While autophagy within the cell provides an intracellular source of amino acids to support anabolism, little is known about how this pathway impacts the insulin-induced increase in anabolic capacity within skeletal muscle cells. PURPOSE: The purpose of this study was to determine the impact of autophagic inhibition in cultured L6 myotubes in conjunction with insulin stimulation in vitro. METHODS: Differentiated, cultured L6 myotubes were treated for 24 hours with or without insulin (100 nM) and NSC 185058 (100 μM), a specialized inhibitor of the autophagic catabolic pathway, in media enriched with 4% deuterium. Cells were harvested from each treatment group (n=3/group) 24 hours post-deuterium enrichment and were processed for protein synthesis and western blot protein analysis. A one-way ANOVA was used to compare groups, and when significant F ratios were present, a Student’s Newman-Keuls post hoc procedure was used to test differences among group means. Alpha was set at p≤0.05 for all analyses. RESULTS: Cells treated with insulin (INS) had a higher ratio of phosphorylated to total P70S6K compared to untreated (CON) cells and those incubated with both insulin and NSC 185058 (INS+NSC; 1694% and 327%, respectively; p\u3c0.05). INS+NSC also decreased the ratio of phosphorylated to total 4EBP1 relative to CON (-51%) and INS (-49%), although these differences were not significant (p\u3e0.05). Myofibrillar protein synthesis was stimulated with INS compared to CON and INS+NSC (30.3% and 70.1% respectively; p\u3c0.05) but was lower in INS+NSC relative to CON (-23.4%; p\u3c0.05). CONCLUSION: Results from our study indicate that insulin (100 nM) stimulates anabolism in skeletal muscle cells, but that addition of the autophagic inhibitor NSC 185058 (100 μM) blunts this effect to a level similar to or less than control. Further, our data suggest that the reduction of protein synthesis is mediated through the downregulation of the mTORC1 signaling pathway. While it is widely recognized that insulin promotes anabolic activity through both the direct stimulation of mTOR signaling and extracellular amino acid uptake, our data strongly indicate that autophagic processes are necessary for full anabolic responses in muscle. This decrease in anabolic capacity supports previous literature indicating that the amino acid availability impacts the stimulatory impact of insulin on protein synthesis

Epithelioid Glioblastoma Presenting as Aphasia in a Young Adult with Ovarian Cancer: A Case Report

Background: Epithelioid glioblastoma (eGBM) is a recent addition to the World Health Organization’s classification of central nervous system (CNS) tumors. This rare lesion has a predilection for younger patients, can mimic metastatic disease on preoperative imaging and intraoperative pathology, and portends a poor prognosis due to propensity for leptomeningeal dissemination. Case Description: We discuss a case of a young woman with a history of ovarian cancer who presented with seizure and a new ring-enhancing left temporal brain lesion. The patient underwent gross-total surgical resection of this lesion, during which frozen section suggested metastasis. However, pathologic interrogation showed pleomorphic epithelioid cells and glial fibrillary acid positivity, suggesting eGBM. The patient has since completed radiotherapy and six-month post-operative imaging has not revealed recurrence or leptomeningeal dissemination. Conclusion: Our patient\u27s clinical history and pre-operative radiographic evaluation suggested CNS metastatic disease. Ultimately, final pathology revealed eGBM, a newly classified CNS primary tumor. This reinforces the importance of direct tissue sampling and including eGBM on the differential for young patients with histories of systemic cancer presenting with new CNS lesions

The Origin of Line Emission in Massive z~2.3 Galaxies: Evidence for Cosmic Downsizing of AGN Host Galaxies

Using the Gemini Near-InfraRed Spectrograph (GNIRS), we have assembled a complete sample of 20 K-selected galaxies at 2.0<z<2.7 with high quality near-infrared spectra. As described in a previous paper, 9 of these 20 galaxies have strongly suppressed star formation and no detected emission lines. The present paper concerns the 11 galaxies with detected Halpha emission, and studies the origin of the line emission using the GNIRS spectra and follow-up observations with SINFONI on the VLT. Based on their [NII]/Halpha ratios, the spatial extent of the line emission and several other diagnostics, we infer that four of the eleven emission-line galaxies host narrow line active galactic nuclei (AGNs). The AGN host galaxies have stellar populations ranging from evolved to star-forming. Combining our sample with a UV-selected galaxy sample at the same redshift that spans a broader range in stellar mass, we find that black-hole accretion is more effective at the high-mass end of the galaxy distribution (~2.9x10^11 Msun) at z~2.3. Furthermore, by comparing our results with SDSS data, we show that the AGN activity in massive galaxies has decreased significantly between z~2.3 and z~0. AGNs with similar normalized accretion rates as those detected in our K-selected galaxies reside in less massive galaxies (~4.0x10^10 Msun) at low redshift. This is direct evidence for downsizing of AGN host galaxies. Finally, we speculate that the typical stellar mass-scale of the actively accreting AGN host galaxies, both at low and at high redshift, might be similar to the mass-scale at which star-forming galaxies seem to transform into red, passive systems.Comment: Accepted for publication in the Astrophysical Journa