Population viability is driven by individual survival, which in turn depends on individuals balancing energy budgets. As carnivores may function close to maximum sustained power outputs, decreased ...food availability or increased activity may render some populations energetically vulnerable. Prey theft may compromise energetic budgets of mesopredators, such as cheetahs and wild dogs, which are susceptible to competition from larger carnivores. We show that daily energy expenditure (DEE) of cheetahs was similar to size-based predictions and positively related to distance traveled. Theft at 25% only requires cheetahs to hunt for an extra 1.1 hour per day, increasing DEE by just 12%. Therefore, not all mesopredators are energetically constrained by direct competition. Other factors that increase DEE, such as those that increase travel, may be more important for population viability.
Background
Isolated limb infusion (ILI) is a minimally invasive procedure for delivering high-dose regional chemotherapy to patients with locally advanced or in-transit melanoma located on a limb. ...The current international multicenter study evaluated the perioperative and long-term oncologic outcomes for patients who underwent ILI for stage 3B or 3C melanoma.
Methods
Patients undergoing a first-time ILI for stage 3B or 3C melanoma (American Joint Committee on Cancer AJCC 7th ed) between 1992 and 2018 at five Australian and four United States of America (USA) tertiary referral centers were identified. The primary outcome measures included treatment response, in-field (IPFS) and distant progression-free survival (DPFS), and overall survival (OS).
Results
A total of 687 first-time ILIs were performed (stage 3B:
n
= 383, 56%; stage 3C;
n
= 304, 44%). Significant limb toxicity (Wieberdink grade 4) developed in 27 patients (3.9%). No amputations (grade 5) were performed. The overall response rate was 64.1% (complete response CR, 28.9%; partial response PR, 35.2%). Stable disease (SD) occurred in 14.5% and progressive disease (PD) in 19.8% of the patients. The median follow-up period was 47 months, with a median OS of 38.2 months. When stratified by response, the patients with a CR or PR had a significantly longer median IPFS (21.9 vs 3.0 months;
p
< 0.0001), DPFS (53.6 vs 12.7 months;
p
< 0.0001), and OS (46.5 vs 24.4 months;
p
< 0.0001) than the nonresponders (SD + PD).
Conclusion
This study is the largest to date reporting long-term outcomes of ILI for locoregionally metastatic melanoma. The findings demonstrate that ILI is effective and safe for patients with stage 3B or 3C melanoma confined to a limb. A favorable response to ILI is associated with significantly longer IFPS, DPFS, and OS.
Background:Basal metabolic rate (BMR) is the largest component of daily energy demand in Western societies. Previous studies indicated that BMR is highly variable, but the cause of this variation is ...disputed. All studies agree that variation in fat-free mass (FFM) plays a major role, but effects of fat mass (FM), age, sex, and the hormones leptin, triiodothyrionine (T3), and thyroxine (T4) remain uncertain.
Objective:We partitioned the variance in BMR into within- and between-subject effects and explored the roles of FFM, FM, bone mineral content, sex, age, and circulating concentrations of plasma leptin, T3, and T4.
Design:This was a cross-sectional study of 150 white adults from northeast Scotland, United Kingdom.
Results:Only 2% of the observed variability in BMR was attributable to within-subject effects, of which 0.5% was analytic error. Of the remaining variance, which reflected between-subject effects, 63% was explained by FFM, 6% by FM, and 2% by age. The effects of sex and bone mineral content were not significant (P> 0.05). Twenty-six percent of the variance remained unexplained. This variation was not associated with concentrations of circulating leptin or T3. T4was not significant in women but explained 25% of the residual variance in men.
Conclusions:Our data confirm that both FFM and FM are significant contributors to BMR. When the effect of FM on BMR is removed, any association with leptin concentrations disappears, which suggests that previous links between circulating leptin concentrations and BMR occurred only because of inadequate control for the effects of FM.
Energetics of flight in bats Speakman, John R
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology,
7/2000, Letnik:
126
Journal Article
Scientists have been measuring energy expenditure by using gas exchange for the past 200 y. This technique is based on earlier work in the 1660s. Gas exchange in respirometers provides accurate and ...repeatable measures of resting metabolic rate. However, it is impossible to duplicate in a respirometry chamber the diversity of human behaviors that influence energy expenditure. The doubly labeled water technique is an isotope-based method that measures the energy expenditure of unencumbered subjects from the divergence in enrichments of 2 isotopic labels in body water—1 of hydrogen and 1 of oxygen. The method was invented in the 1950s and applied to small animals only until the early 1980s, mostly because of the expense. Since 1982, when the first study in humans was published, its use has expanded enormously. Although there is some debate over the precise calculation protocols that should be used, the differences between alternative calculations result in relatively minor effects on total energy expenditure estimates (≈6%). Validation studies show that for groups of subjects the method works well, but that precision is still relatively poor (8–9%) and consequently the method is not yet sufficiently refined to provide estimates of individual energy expenditures.
Bats seldom soar because it is behaviour generally associated with the use of thermals, which are normally of insufficient strength at night to support the behaviour. Daylight flying bats, however, ...such as the Samoan flying fox Pteropus samoensis may be able to exploit thermals for soaring. This may give the bats one of two advantages. It may reduce the energy costs of transport because gliding flight is much cheaper than active flapping flight. However, because less endogenous heat is generated by soaring, a second advantage may be that it reduces the thermal stress placed on these bats. Thermal stress is a factor that we have shown previously probably constrains the daylight flying behaviour of this species. Observations of the patterns of soaring behaviour at two sites on American Samoa in March and October 1995 supported the predictions of the energy saving but not the hyperthermia avoidance hypothesis. Soaring was a common behaviour under all conditions and was used extensively when conditions did not pose a threat of hyperthermia. In March, the bats also adopted flight patterns over time that exposed them to areas of the valleys where insolation was greatest, presumably increasing their risk of hyperthermia but bringing energy saving benefits. Modelling the expected heat flows during soaring and flapping flight using an established model revealed that soaring reduced the risk of hyperthermia, when flying in the shade of clouds, because of the energy savings resulting from reduced endogenous heat production. However, when soaring in sunlight, these savings are more than offset by the increased exogenous heat uptake, because a greater proportion of the wing surface is exposed when soaring. Despite its low endogenous energy cost, soaring in sunlight is not thermally advantageous, and the behaviour of the bats reflected this fact.
Key questions in marine mammal bioenergetics McHuron, Elizabeth A; Adamczak, Stephanie; Arnould, John P Y ...
Conservation physiology,
01/2022, Letnik:
10, Številka:
1
Journal Article
Odprti dostop
Marine mammals are facing many threats that impact their ability to obtain energy to survive and reproduce. Much remains unknown about marine mammal bioenergetics, which hinders real-world ...applications to conservation and management. We surveyed the bioenergetic community to identify ‘key’ unanswered questions to help guide future marine mammal research efforts.
Abstract
Bioenergetic approaches are increasingly used to understand how marine mammal populations could be affected by a changing and disturbed aquatic environment. There remain considerable gaps in our knowledge of marine mammal bioenergetics, which hinder the application of bioenergetic studies to inform policy decisions. We conducted a priority-setting exercise to identify high-priority unanswered questions in marine mammal bioenergetics, with an emphasis on questions relevant to conservation and management. Electronic communication and a virtual workshop were used to solicit and collate potential research questions from the marine mammal bioenergetic community. From a final list of 39 questions, 11 were identified as ‘key’ questions because they received votes from at least 50% of survey participants. Key questions included those related to energy intake (prey landscapes, exposure to human activities) and expenditure (field metabolic rate, exposure to human activities, lactation, time-activity budgets), energy allocation priorities, metrics of body condition and relationships with survival and reproductive success and extrapolation of data from one species to another. Existing tools to address key questions include labelled water, animal-borne sensors, mark-resight data from long-term research programs, environmental DNA and unmanned vehicles. Further validation of existing approaches and development of new methodologies are needed to comprehensively address some key questions, particularly for cetaceans. The identification of these key questions can provide a guiding framework to set research priorities, which ultimately may yield more accurate information to inform policies and better conserve marine mammal populations.
'In the 15 minutes it will take you to read this article nine people in the USA, and one person in the UK, will have died as a direct consequence of obesity related illnesses.'
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