Search results for "Life Span"
showing 10 items of 41 documents
Inflammation and Life-Span
2005
In their Review “Inflammatory exposure and historical changes in human life-spans” (17 Sept., p. [1736][1]), C. E. Finch and E. M. Crimmins reinforce earlier suggestions that many diseases and disabilities of older age have their roots in previous exposures to infectious agents and other sources
Theories and Mechanisms of Aging
2013
The more one learns about single processes and genes known to be involved in aging, the more it becomes evident that these are connected and there is no unifying theory of aging. The individual theories put individual factors and processes in focus and for each theory there are direct links to life span or to age-related disorders. In the following chapter, the key theories of aging focusing on telomeres, DNA damage, oxidative stress as well as possible roles of nutrition, the interplay between genes and environment (epigenetics) and cellular protein homeostasis are presented. In animal models the life span can be altered by targeting specific genes, proteins and signalling pathways. After …
Removal of failed crown and bridge
2011
Crown and bridge have life span of many years but they fail for a number of reasons. Over the years, many devices have been designed to remove crowns and bridges from abutment teeth. While the removal of temporary crowns and bridges is usually very straightforward, the removal of a definitive cast crown with unknown cement is more challenging. Removal is often by destructive means. There are a number of circumstances, however, in which conservative disassembly would aid the practitioner in completing restorative/endodontic procedures. There are different mechanisms available to remove a failed crown or bridge. But there is no information published about the classification of available syste…
Seasonal periodicity of growth and composition in valves of Diplodon chilensis patagonicus (d'Orbigny, 1835)
2008
Freshwater mussels of the genus Diplodon (Unionida) are common inhabitants of lakes and rivers in South America, and have slow growth and long life spans. We established the annual periodicity of incremental shell growth in Diplodon chilensis patagonicus (d'Orbigny, 1835) and calculated growth rates at different ages, using internal ring counting supported by dyeing methods and δ 18 O isotope analyses, in two Patagonian populations (Lago Steffen and its effluent Rio Manso Inferior, Argentina). Longevities of ca. 90 years (Lago Steffen) significantly extend the life spans reported in the past. Growth rates for old individuals (>30 years) from both lake and river populations average 0.16 mm p…
Women Live Longer than Men: Understanding Molecular Mechanisms Offers Opportunities to Intervene by Using Estrogenic Compounds
2010
Abstract Women live longer than men. Moreover, females live longer than males in some, but not all, experimental animals. The differences in longevity between genders are related to free radical production. Indeed, females produce less radicals only in animal species in which they live longer than males. This is because estrogens upregulate antioxidant longevity-related genes. These considerations have led us to postulate an extended concept of antioxidant in biology: an antioxidant is any nutritional, physiological, or pharmacological manipulation that increases the expression and activity of antioxidant genes or proteins. Phytoestrogens or other selective estrogen receptor modulators lowe…
Life-history differences in age-dependent expressions of multiple ornaments and behaviors in a lekking bird
2015
Age is a major factor explaining variation in life-history traits among individuals with typical patterns of increasing trait values early in life, maximum trait expression, and senescence. However, age-dependent variation in the expressions of sexually selected traits has received less attention, although such variation underpins differences in male competitive abilities and female preference, which are central to sexual selection. In contrast to previous studies focusing on single traits, we used repeated measures of seven sexually selected morphological and behavioral traits in male black grouse (Tetrao tetrix) to quantify the effects of age and life span on their expressions and quantif…
Mitochondrial damage in aging and apoptosis.
2002
: Mitochondria are essential to cellular aging, and free radical production by mitochondria is increased with aging. The rate of oxidant production by mitochondria correlates inversely with maximal life span of species. In many species, females live longer than males. We report that mitochondrial oxidant production by females is significantly lower than that of males. However, mitochondria from ovariectomized females have a similar oxidant production as those of males. Thus, gender difference in life span can be explained, at least in part, by different oxidant generation by mitochondria. Administration of antioxidants, such as vitamins C and E, or a Ginkgo biloba extract, protects against …
Expanded CTG repeats trigger miRNA alterations in Drosophila that are conserved in myotonic dystrophy type 1 patients
2013
Myotonic dystrophy type 1 (DM1) is caused by the expansion of CTG repeats in the 3' untranslated region of the DMPK gene. Several missplicing events and transcriptional alterations have been described in DM1 patients. A large number of these defects have been reproduced in animal models expressing CTG repeats alone. Recent studies have also reported miRNA dysregulation in DM1 patients. In this work, a Drosophila model was used to investigate miRNA transcriptome alterations in the muscle, specifically triggered by CTG expansions. Twenty miRNAs were differentially expressed in CTG-expressing flies. Of these, 19 were down-regulated, whereas 1 was up-regulated. This trend was confirmed for thos…
Life span, dispersal and age of nesting Great Grey Owls (Strix nebulosa lapponica) in Sweden.
2016
3,073 Great Grey Owls were banded in Sweden in 1955–2012. 416 were controlled at least once (54.6%) or recovered dead (45.4%). Three birds banded as nestlings were recovered in their 17th calendar year. Most birds were recovered during first year of life. Only 4 females were controlled breeding as 2CY birds. 91.3% of birds controlled as first time breeders were at least 4CY. Birds banded as nestlings and recovered dead between September and July moved 100.8 km (mean) with a median distance of 64 km. Juveniles controlled alive moved 45.9 km (mean) with a median distance of 23 km during first year of life. Maximum natal dispersal was 650 km. Median natal dispersal for females was 40 km, betwe…
Leaf life span and the mobility of "non-mobile" mineral nutrients - The case of boron in conifers
2002
Nutrient conservation is considered important for the adaptation of plants to infertile environments. The importance of leaf life spans in controlling mean residence time of nutrients in plants has usually been analyzed in relation to nutrients that can be retranslocated within the plant. Longer leaf life spans increase the mean residence time of all mineral nutrients, but for non-mobile nutrients long leaf life spans concurrently cause concentrations in tissues to increase with leaf age, and consequently may reduce non-mobile nutrient use efficiency. Here we analyze how the role of leaf life span is related to the mobility of nutrients within the plant. We use optimality concepts to derive…