Effects of an invasive consumer on zooplankton communities are unaltered by nutrient inputs

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Similar hypotensive responses to resistance exercise with and without blood flow restriction

Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances.     

Food web structure changes with elevation but not rainforest stratum

Changes in species richness along elevational gradients are well documented. However, little is known about how trophic interactions between species and, in particular, the food webs that these interactions comprise, change with elevation. Here we present results for the first comparison of quantitative food webs in forest understorey and canopy along an elevational gradient. Replicate quantitative food webs were constructed for assemblages involving 23 species of cavity‐nesting Hymenoptera and 12 species of their parasitoids and kleptoparasites in subtropical rainforest in Australia. A total of 1589 insects were collected using trap nests across 20 plots distributed at sites ranging from 300 to 1100 m a.s.l. Insect abundance, insect diversity and parasitism rate generally decreased with increasing elevation. Food web structure significantly changed with elevation. In particular, weighted quantitative measures of linkage density, interaction evenness, nestedness (weighted NODF) and potential for enemy mediated interactions (PAC) decreased with increasing elevation, and network specialisation (H₂′) increased with increasing elevation, even after controlling for matrix size; but there was no change in weighted connectance. Changes in forest type and temperature along the elevational gradient are likely to be, at least partly, responsible for the patterns observed. We found no significant differences in insect abundance, insect diversity or parasitism rate between canopy and understorey. Furthermore, there were no differences in food web structure between strata. These results contribute further evidence to studies revealing changes in food web structure along natural environmental gradients and provide information that can potentially be used for predicting how communities may respond to climate change.     

Cellular Models of Aggregation-dependent Template-directed Proteolysis to Characterize Tau Aggregation Inhibitors for Treatment of Alzheimer Disease

Alzheimer disease (AD) is a degenerative tauopathy characterized by aggregation of Tau protein through the repeat domain to form intraneuronal paired helical filaments (PHFs). We report two cell models in which we control the inherent toxicity of the core Tau fragment. These models demonstrate the properties of prion-like recruitment of full-length Tau into an aggregation pathway in which template-directed, endogenous truncation propagates aggregation through the core Tau binding domain. We use these in combination with dissolution of native PHFs to quantify the activity of Tau aggregation inhibitors (TAIs). We report the synthesis of novel stable crystalline leucomethylthioninium salts (LMTX®), which overcome the pharmacokinetic limitations of methylthioninium chloride. LMTX®, as either a dihydromesylate or a dihydrobromide salt, retains TAI activity in vitro and disrupts PHFs isolated from AD brain tissues at 0.16 μm. The K_i value for intracellular TAI activity, which we have been able to determine for the first time, is 0.12 μm. These values are close to the steady state trough brain concentration of methylthioninium ion (0.18 μm) that is required to arrest progression of AD on clinical and imaging end points and the minimum brain concentration (0.13 μm) required to reverse behavioral deficits and pathology in Tau transgenic mice.     

Cold truths: how winter drives responses of terrestrial organisms to climate change

Winter is a key driver of individual performance, community composition, and ecological interactions in terrestrial habitats. Although climate change research tends to focus on performance in the growing season, climate change is also modifying winter conditions rapidly. Changes to winter temperatures, the variability of winter conditions, and winter snow cover can interact to induce cold injury, alter energy and water balance, advance or retard phenology, and modify community interactions. Species vary in their susceptibility to these winter drivers, hampering efforts to predict biological responses to climate change. Existing frameworks for predicting the impacts of climate change do not incorporate the complexity of organismal responses to winter. Here, we synthesise organismal responses to winter climate change, and use this synthesis to build a framework to predict exposure and sensitivity to negative impacts. This framework can be used to estimate the vulnerability of species to winter climate change. We describe the importance of relationships between winter conditions and performance during the growing season in determining fitness, and demonstrate how summer and winter processes are linked. Incorporating winter into current models will require concerted effort from theoreticians and empiricists, and the expansion of current growing‐season studies to incorporate winter.     

Impact of death and dying on the personal lives and practices of palliative and hospice care professionals

Background

Working within the landscape of death and dying, professionals in palliative and hospice care provide insight into the nature of mortality that may be of benefit to individuals facing the end of life. Much less is known about how these professionals incorporate these experiences into their personal lives and clinical practices.

Methods

This ethnographic inquiry used semi-structured interviews and participant observation to elicit an in-depth understanding of the impact of death and dying on the personal lives of national key leaders (n = 6) and frontline clinicians (n = 24) involved in end-of-life care in Canada. Analysis of findings occurred in the field through constant comparative method and member checking, with more formal levels of analysis occurring after the data-collection phase.

Results

Eleven specific themes, organized under three overarching categories (past, present and future), were discovered. Early life experiences with death were a common and prominent feature, serving as a major motivator in participants’ career path of end-of-life care. Clinical exposure to death and dying taught participants to live in the present, cultivate a spiritual life, reflect on their own mortality and reflect deeply on the continuity of life.

Interpretation

Participants reported that their work provided a unique opportunity for them to discover meaning in life through the lessons of their patients, and an opportunity to incorporate these teachings in their own lives. Although Western society has been described as a “death-denying” culture, the participants felt that their frequent exposure to death and dying was largely positive, fostering meaning in the present and curiosity about the continuity of life.Although preserving life is a central goal of medicine, in the end, death is an unavoidable outcome. Professionals in palliative and hospice care, working within the landscape of death and dying, are able to provide insight into death-related experiences and have the opportunity to incorporate these experiences into their personal and professional lives. The ability for death to foster meaning in life has been attested to by wisdom traditions and palliative care professionals alike. The latter usually provide rich accounts of the struggles of dying individuals, and in some instances, accounts of individuals who discovered meaning and purpose within this landscape.Although an expansive body of literature has evolved exploring the spiritual and existential impact of death and dying, these studies focused predominately on the impact on patients and occasionally on family members.^1–5 A small number of studies discussed the residual impact of end-of-life care within a localized group of health care providers; however, there is limited cross-sectional research explicitly investigating the long-term effect of death and dying on the personal and professional lives of individuals who are exposed to death and dying on a frequent basis.^6–15To address these gaps in the literature, this study explored the impact of death and dying on the lives of key leaders and frontline professionals in palliative and hospice care — individuals who arguably provide society and health care practitioners with the most authoritative discourse on end of life and its effect on life in general. This study was part of a larger ethnographic inquiry on the spirituality of palliative and hospice care professionals in Canada.     

Reasons given by general practitioners for non-treatment decisions in younger and older patients with newly diagnosed type 2 diabetes mellitus in the United Kingdom: a survey study

Background

Hyperthyroidism is accompanied by osteoporosis with higher incidence of fracture rates. The present work aimed to study bone status in hyperthyroidism and to elucidate the impact of severity, duration, and etiology of hyperthyroidism on biochemical markers of bone turnover and bone mineral density (BMD).

Methods

Fifty-two male patients with hyperthyroidism, 31 with Graves' disease (GD) and 21 with toxic multinodular goiter (TNG), with an age ranging from 23 to 65 years were included, together with 25 healthy euthyroid men with matched age as a control group. In addition to full clinical examination, patients and controls were subjected to measurement of BMD using dual-energy X-ray absorptiometery scanning of the lower half of the left radius. Also, some biochemical markers of bone turnover were done for all patients and controls.

Results

Biochemical markers of bone turnover: included serum bone specific alkaline phosphatase, osteocalcin, carboxy terminal telopeptide of type l collagen also, urinary deoxypyridinoline cross-links (DXP), urinary DXP/urinary creatinine ratio and urinary calcium/urinary creatinine ratio were significantly higher in patients with GD and TNG compared to controls (P < 0.01). However, there was non-significant difference in these parameters between GD and TNG patients (P > 0.05). BMD was significantly lower in GD and TNG compared to controls, but the Z-score of BMD at the lower half of the left radius in patients with GD (-1.7 ± 0.5 SD) was not significantly different from those with TNG (-1.6 ± 0.6 SD) (>0.05). There was significant positive correlation between free T3 and free T4 with biochemical markers of bone turnover, but negative correlation between TSH and those biochemical markers of bone turnover. The duration of the thyrotoxic state positively correlated with the assessed bone turnover markers, but it is negatively correlated with the Z-score of BMD in the studied hyperthyroid patients (r = -0.68, P < 0.0001).

Conclusion

Men with hyperthyroidism have significant bone loss with higher biochemical markers of bone turnover. The severity and the duration of the thyrotoxic state are directly related to the derangement of biochemical markers of bone turnover and bone loss.     

The relationship between chill-coma onset and recovery at the extremes of the thermal window of Drosophila melanogaster

Critical thermal minimum (CT(min)), a measure of chill-coma onset temperature, and chill-coma recovery (CCR), the time taken to recover from chill coma, are common metrics of thermal tolerance in insects. We investigated the relationship between CT(min) and CCR in a single population of adult Drosophila melanogaster exposed to a range of rearing (14°, 21.5°, and 27°C), acclimation (5 d at 6° or 29°C), and hardening (1 h at 0° or 36°C) conditions. CT(min) ranged from -4.2° to 8.8°C and CCR from 12.1 to 55.1 min, and CT(min) and CCR varied in the same direction: populations with low CT(min) tended to have short CCR. Acclimation had a greater effect on CT(min) and CCR than short-term hardening. There was a significant positive rank correlation between CT(min) and CCR, but the relationship was demonstrably curvilinear, suggesting that although plasticity in these measures is correlated through the central part of the relationship, there is no relationship between CT(min) and CCR across a range of values generated by phenotypic plasticity. This implies that the mechanisms underlying plasticity in CT(min) are not entirely shared with those underlying CCR.