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  • 1
    In: GeroScience, Springer Science and Business Media LLC, Vol. 44, No. 3 ( 2022-06), p. 1641-1655
    Abstract: Prolonging survival in good health is a fundamental societal goal. However, the leading determinants of disability-free survival in healthy older people have not been well established. Data from ASPREE, a bi-national placebo-controlled trial of aspirin with 4.7 years median follow-up, was analysed. At enrolment, participants were healthy and without prior cardiovascular events, dementia or persistent physical disability. Disability-free survival outcome was defined as absence of dementia, persistent disability or death. Selection of potential predictors from amongst 25 biomedical, psychosocial and lifestyle variables including recognized geriatric risk factors, utilizing a machine-learning approach. Separate models were developed for men and women. The selected predictors were evaluated in a multivariable Cox proportional hazards model and validated internally by bootstrapping. We included 19,114 Australian and US participants aged ≥65 years (median 74 years, IQR 71.6–77.7). Common predictors of a worse prognosis in both sexes included higher age, lower Modified Mini-Mental State Examination score, lower gait speed, lower grip strength and abnormal (low or elevated) body mass index. Additional risk factors for men included current smoking, and abnormal eGFR. In women, diabetes and depression were additional predictors. The biased-corrected areas under the receiver operating characteristic curves for the final prognostic models at 5 years were 0.72 for men and 0.75 for women. Final models showed good calibration between the observed and predicted risks. We developed a prediction model in which age, cognitive function and gait speed were the strongest predictors of disability-free survival in healthy older people. Trial registration Clinicaltrials.gov (NCT01038583)
    Type of Medium: Online Resource
    ISSN: 2509-2715 , 2509-2723
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2886418-9
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  • 2
    In: PLOS ONE, Public Library of Science (PLoS), Vol. 10, No. 7 ( 2015-7-6), p. e0131275-
    Type of Medium: Online Resource
    ISSN: 1932-6203
    Language: English
    Publisher: Public Library of Science (PLoS)
    Publication Date: 2015
    detail.hit.zdb_id: 2267670-3
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  • 3
    Online Resource
    Online Resource
    Elsevier BV ; 2011
    In:  Journal of Insect Physiology Vol. 57, No. 8 ( 2011-8), p. 1066-1069
    In: Journal of Insect Physiology, Elsevier BV, Vol. 57, No. 8 ( 2011-8), p. 1066-1069
    Type of Medium: Online Resource
    ISSN: 0022-1910
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2011
    detail.hit.zdb_id: 1482429-2
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Elsevier BV ; 2004
    In:  Journal of Insect Physiology Vol. 50, No. 10 ( 2004-10), p. 943-953
    In: Journal of Insect Physiology, Elsevier BV, Vol. 50, No. 10 ( 2004-10), p. 943-953
    Type of Medium: Online Resource
    ISSN: 0022-1910
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2004
    detail.hit.zdb_id: 1482429-2
    SSG: 12
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  • 5
    In: Journal of Experimental Biology, The Company of Biologists
    Abstract: Food shortage represents a primary challenge to survival, and animals have adapted diverse developmental, physiological, and behavioral strategies to survive when food becomes unavailable. Starvation resistance is strongly influenced by ecological and evolutionary history, yet the genetic basis for the evolution of starvation resistance remains poorly understood. The fruit fly, Drosophila melanogaster, provides a powerful model for leveraging experimental evolution to investigate traits associated with starvation resistance. While control populations only live a few days without food, selection for starvation resistance results in populations that can survive weeks. We have previously shown that selection for starvation resistance results in increased sleep and reduced feeding in adult flies. Here, we investigate the ontogeny of starvation resistance-associated behavioral and metabolic phenotypes in these experimentally selected flies. We find that selection for starvation resistance results in delayed development and a reduction in metabolic rate in larvae that persists into adulthood, suggesting that these traits may allow for the accumulation of energy stores and an increase in body size within these selected populations. In addition, we find that larval sleep is largely unaffected by starvation selection and that feeding increases during the late larval stages, suggesting that experimental evolution for starvation resistance produces developmentally specified changes in behavioral regulation. Together, these findings reveal a critical role for development in the evolution of starvation resistance and indicate that selection can selectively influence behavior during defined developmental timepoints.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2019
    detail.hit.zdb_id: 1482461-9
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  • 6
    Online Resource
    Online Resource
    The Company of Biologists ; 2001
    In:  Journal of Experimental Biology Vol. 204, No. 13 ( 2001-07-01), p. 2331-2338
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 204, No. 13 ( 2001-07-01), p. 2331-2338
    Abstract: Fruit flies of the genus Drosophila have independently invaded deserts around the world on numerous occasions. To understand the physiological mechanisms allowing these small organisms to survive and thrive in arid environments, we performed a phylogenetic analysis of water balance in Drosophila species from different habitats. Desert (cactophilic) species were more resistant to desiccation than mesic ones. This resistance could be accomplished in three ways: by increasing the amount of water in the body, by reducing rates of water loss or by tolerating the loss of a greater percentage of body water (dehydration tolerance). Cactophilic Drosophila lost water less rapidly and appeared to be more tolerant of low water content, although males actually contained less water than their mesic congeners. However, when the phylogenetic relationships between the species were taken into account, greater dehydration tolerance was not correlated with increased desiccation resistance. Therefore, only one of the three expected adaptive mechanisms, lower rates of water loss, has actually evolved in desert Drosophila, and the other apparently adaptive difference between arid and mesic species (increased dehydration tolerance) instead reflects phylogenetic history.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2001
    detail.hit.zdb_id: 1482461-9
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  • 7
    Online Resource
    Online Resource
    The Company of Biologists ; 2006
    In:  Journal of Experimental Biology Vol. 209, No. 17 ( 2006-09-01), p. 3293-3300
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 209, No. 17 ( 2006-09-01), p. 3293-3300
    Abstract: We studied larval development and acquisition of metabolic resources in Drosophila melanogaster selected for adult desiccation resistance. Desiccation-selected (D) flies had longer developmental times in comparison with control populations, resulting in significantly higher body mass. No differences were found in larval growth rates, suggesting that increased body mass results from the extended larval feeding period. Larvae from both D and control lines molted from second to third instar 81-84 h after egg laying,whereas D larvae pupated 5-6 h later than controls. This indicates that selecting adults for desiccation resistance results in longer third larval instar. Newly eclosed D flies had higher carbohydrate and water contents in comparison with control populations. No differences were found in body mass,water or metabolite contents of newly eclosed selected and control flies after larvae were prevented from further feeding from 96 h after egg laying onwards. This shows that differences in accumulated carbohydrate and water stores are a result of evolved differences in the duration of third larval instar. The contribution of third instar feeding to desiccation resistance of adult selected flies is higher than that of controls. Thus, selection for adult stress resistance has resulted in correlated changes in larval physiology.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2006
    detail.hit.zdb_id: 1482461-9
    SSG: 12
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  • 8
    Online Resource
    Online Resource
    The Company of Biologists ; 2007
    In:  Journal of Experimental Biology Vol. 210, No. 20 ( 2007-10-15), p. 3547-3558
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 210, No. 20 ( 2007-10-15), p. 3547-3558
    Abstract: In natural environments where food abundance and quality can change drastically over time, animals must continuously alter their food acquisition strategies. Although genetic variation contributes to this plasticity, the specific genes involved and their interactions with the environment are poorly understood. Here we report that natural variation in the Drosophilagene, foraging (for), which encodes a cGMP-dependent protein kinase (PKG), affects larval food acquisition in an environmentally dependent fashion. When food is plentiful, the wild-type rover(forR) allele confers lower food intake and higher glucose absorption than both the wild-type sitter (fors) allele and the mutant fors2 allele. When food is scarce, forR, fors and fors2 larvae increase food intake to a common maximal level, but forRlarvae retain their increased absorption efficiency. Changes in forexpression can induce corrective behavioral modifications in response to food deprivation. When reared in environments with low food levels, forR larvae have higher survivorship and faster development than fors and fors2larvae. Together, these results show that natural variation in forhas far reaching implications affecting a suite of phenotypes involved in the regulation of food acquisition.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2007
    detail.hit.zdb_id: 1482461-9
    SSG: 12
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  • 9
    Online Resource
    Online Resource
    The Company of Biologists ; 2004
    In:  Journal of Experimental Biology Vol. 207, No. 20 ( 2004-09-15), p. 3477-3482
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 207, No. 20 ( 2004-09-15), p. 3477-3482
    Abstract: Insects breathe through valved openings (spiracles) in their cuticle. Many insects open and close their spiracles in a cyclic pattern (discontinuous gas-exchange cycles, or DGC). These cycles were observed over half a century ago, their hypothesized function being to minimize loss of water from the tracheal system. However, numerous recent studies have found that respiration accounts for a small fraction of total water loss, and that insects stop performing DGC at times when this pattern would be most useful. Thus, the importance of cyclic gas exchange for water conservation has been challenged. The leading alternative is the chthonic hypothesis, which proposes that DGC originated in insects from hypercapnic (high CO2) environments(e.g. burrows) to aid in release of carbon dioxide. By keeping the spiracles closed, insects would concentrate CO2 and increase the gradient for outward diffusion of CO2. CO2 would be released rapidly when the spiracles opened, and respiratory water loss would be reduced. The chthonic hypothesis therefore predicts that DGC minimizes the ratio of respiratory water loss to CO2 release relative to other modes of gas exchange. We tested the chthonic hypothesis by simultaneously measuring water loss and CO2 release in reproductive females (queens) of the seed-harvester ant Pogonomyrmex barbatus, a burrowing species from North American deserts. Queens used one of three patterns of gas exchange,discontinuous, cyclic and continuous. We resolved the problem of separating cuticular transpiration and respiratory water loss for individuals that used continuous gas exchange by developing a regression method that can be used across all patterns of gas exchange. The ratio of respiratory water loss to CO2 release did not differ among ants using different patterns of gas exchange, in contrast to the expectation of the chthonic hypothesis. Metabolic rate, however, varied with gas-exchange pattern, and was lowest for individuals that used discontinuous gas exchange, intermediate for individuals using cyclic gas exchange, and highest for individuals using continuous gas exchange.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2004
    detail.hit.zdb_id: 1482461-9
    SSG: 12
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  • 10
    Online Resource
    Online Resource
    Elsevier BV ; 2003
    In:  Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology Vol. 135, No. 3 ( 2003-7), p. 457-465
    In: Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Elsevier BV, Vol. 135, No. 3 ( 2003-7), p. 457-465
    Type of Medium: Online Resource
    ISSN: 1095-6433
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2003
    detail.hit.zdb_id: 1481599-0
    SSG: 12
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