Lesson Three Ventricular premature complexes

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What determines ageing of the transplanted liver?

Background

Liver transplantation is used to treat patients with irreversible liver failure from a variety of causes. Long-term survival has been reported, particularly in the paediatric population, with graft survival longer than 20 years now possible. The goal for paediatric liver transplantation is to increase the longevity of grafts to match the normal life expectancy of the child. This paper reviews the literature on the current understanding of ageing of the liver and biomarkers that may predict long-term survival or aid in utilization of organs.

Methods

Scientific papers published from 1950 to 2013 were sought and extracted from the MEDLINE, PubMed and University of Melbourne databases.

Results

Hepatocytes appear resistant to the ageing process, but are affected by both replicative senescence and stress-related senescence. These processes may be exacerbated by the act of transplantation. The most studied biomarkers are telomeres and SMP-30.

Conclusion

There are many factors that play a role in the ageing of the liver. Further studies into biomarkers of ageing and their relationship to the chronological age of the liver are required to aid in predicting long-term graft survival and utilization of organs.     

Which model of successful ageing should be used? Baseline findings from a British longitudinal survey of ageing

BACKGROUND: there is increasing interest in how to age 'successfully' and in reaching consensus over its definition. OBJECTIVE: to assess different models of successful ageing, using a British longitudinal survey of ageing in 2000-1. SETTING: community settings in Britain. METHODS: five models of successful ageing were tested on a British cross-sectional population survey of 999 people aged 65+. The models were biomedical, broader biomedical, social, psychological and lay based. RESULTS: the lay model emerged as the strongest. Respondents who were classified as successfully aged with this model, compared with those not successfully aged, had over five times the odds of rating their quality of life (QoL) as good rather than not good [odds ratio (OR) = 5.493, 95% confidence interval (95% CI) = 2.655-11.364]. CONCLUSION: the lay-based, more multidimensional, model of successful ageing predicted perceived QoL more powerfully than unidimensional models and should be used to evaluate the outcomes of health promotion in older populations.     

Are rates of ageing determined in utero?

BACKGROUND: epidemiological studies have shown that poor early growth is associated with cardiovascular and other degenerative diseases. This has been explained by programming, whereby undernutrition and other influences which restrict early growth permanently change the structure and physiology of the body. The long-term effects of poor early nutrition on ageing have been demonstrated in animals but not studied in man. OBJECTIVES: to determine if poor early growth was associated with increased markers of ageing in later life. METHODS: we traced 1428 men and women, born in Hertfordshire between 1920 and 1930, for whom records of early weight were available. 824 (58%) were interviewed at home and 717 (50%) attended clinic for eye examination, audiometry, grip strength measurement, skin thickness ultrasound and anthropometry. RESULTS: lower weight at 1 year was associated with increased lens opacity score, higher hearing threshold, reduced grip strength and thinner skin. Visual acuity, macular degeneration and intraocular pressure were not related to early growth. CONCLUSIONS: the associations between early growth and markers of ageing suggest that in some systems, ageing may be programmed by events in early life. A potential mechanism is the impaired development of repair systems.     

Does ageing affect zinc homeostasis and dietary requirements?

Dietary intakes of zinc are lower in the elderly because of reduced energy requirements, and it is not clear whether ageing impacts on adaptive homeostatic mechanisms, namely absorptive efficiency and endogenous losses in the GI tract. Physiological requirements for zinc are unlikely to change significantly, but there are several attributes of ageing that may affect aspects of zinc metabolism (e.g. changes in gut structure and function, disease states, chronic inflammation, epigenetic changes in genes that express zinc-related proteins and drug regimens) that are worthy of further investigation. There is, as yet, no information on the effects of ageing on zinc transporters, and there are no sensitive and specific measures of zinc status, therefore dietary recommendations for zinc have been derived from factorial calculations using information on zinc absorption and loss, and estimates of dietary bioavailability.     

Interleukin-1β induced premature senescence of articular chondrocytes

Objective To study whether IL-1β, a catabolic factor of cartilage metabolism, induces premature senescence of articular chondrocytes, and whether caveolin-1 mediates IL-1β-induced cellular senescence. Methods Cultured human articular chondrocytes were stimulated with 10 ng/ml IL-1β. Cellular senescent phenotypes were analyzed by cellular morphology, cell growth arrest (flow cytometry), telomere erosion (Southern blotting), life span (population doublings), and specific senescence-associated β-galac-tosidase (SA-β-Gal) activity. Expression level of caveolin-1 was modulated by anti-sense oligunucleotide or transfection of caveolin-1 gene. Caveolin-1 protein was analyzed by Western blotting. Results Incubation of chondrocytes with IL-1β markedly increase the percentage of cells in G0/G1 phase and reduce the percentage in S phase. Single stimulation with IL-1β enables chondrocytes to become big and flat, and SA-β-Gal activity in chondrocytes is enhanced. Repeated stimulation with IL-Iβ resulted in accelerats erosion of mean telomere length, and shortens life span. Down-regulation of caveolin-1 with anti-sense oligonucleotide significantly inhibits the features of chondrocytes senescence induced by IL-1β. In contrast, caveolin-1 overexpreasion enhanced SA-β-Gal activity in the chondrocytes. Conclusion IL-1β induces features of stress-induced premature senescence and telemere-dependent replicative senescence of articular chondrocytes, which is mediated by caveolin-1. These data suggest that IL-1β induces premature senescence of articular chondro-cytes by upregulation of caveolin-1, which facilitates the development of osteoarthritis.     

Interleukin-1β induced premature senescence of articular chondrocytes

Objective To study whether IL-1β, a catabolic factor of cartilage metabolism, induces premature senescence of articular chondrocytes, and whether caveolin-1 mediates IL-1β-induced cellular senescence. Methods Cultured human articular chondrocytes were stimulated with 10 ng/ml IL-1β. Cellular senescent phenotypes were analyzed by cellular morphology, cell growth arrest (flow cytometry), telomere erosion (Southern blotting), life span (population doublings), and specific senescence-associated β-galac-tosidase (SA-β-Gal) activity. Expression level of caveolin-1 was modulated by anti-sense oligunucleotide or transfection of caveolin-1 gene. Caveolin-1 protein was analyzed by Western blotting. Results Incubation of chondrocytes with IL-1β markedly increase the percentage of cells in G0/G1 phase and reduce the percentage in S phase. Single stimulation with IL-1β enables chondrocytes to become big and flat, and SA-β-Gal activity in chondrocytes is enhanced. Repeated stimulation with IL-Iβ resulted in accelerats erosion of mean telomere length, and shortens life span. Down-regulation of caveolin-1 with anti-sense oligonucleotide significantly inhibits the features of chondrocytes senescence induced by IL-1β. In contrast, caveolin-1 overexpreasion enhanced SA-β-Gal activity in the chondrocytes. Conclusion IL-1β induces features of stress-induced premature senescence and telemere-dependent replicative senescence of articular chondrocytes, which is mediated by caveolin-1. These data suggest that IL-1β induces premature senescence of articular chondro-cytes by upregulation of caveolin-1, which facilitates the development of osteoarthritis.     

Interleukin-1β induced premature senescence of articular chondrocytes

Objective To study whether IL-1β, a catabolic factor of cartilage metabolism, induces premature senescence of articular chondrocytes, and whether caveolin-1 mediates IL-1β-induced cellular senescence. Methods Cultured human articular chondrocytes were stimulated with 10 ng/ml IL-1β. Cellular senescent phenotypes were analyzed by cellular morphology, cell growth arrest (flow cytometry), telomere erosion (Southern blotting), life span (population doublings), and specific senescence-associated β-galac-tosidase (SA-β-Gal) activity. Expression level of caveolin-1 was modulated by anti-sense oligunucleotide or transfection of caveolin-1 gene. Caveolin-1 protein was analyzed by Western blotting. Results Incubation of chondrocytes with IL-1β markedly increase the percentage of cells in G0/G1 phase and reduce the percentage in S phase. Single stimulation with IL-1β enables chondrocytes to become big and flat, and SA-β-Gal activity in chondrocytes is enhanced. Repeated stimulation with IL-Iβ resulted in accelerats erosion of mean telomere length, and shortens life span. Down-regulation of caveolin-1 with anti-sense oligonucleotide significantly inhibits the features of chondrocytes senescence induced by IL-1β. In contrast, caveolin-1 overexpreasion enhanced SA-β-Gal activity in the chondrocytes. Conclusion IL-1β induces features of stress-induced premature senescence and telemere-dependent replicative senescence of articular chondrocytes, which is mediated by caveolin-1. These data suggest that IL-1β induces premature senescence of articular chondro-cytes by upregulation of caveolin-1, which facilitates the development of osteoarthritis.     

Interleukin-1β induced premature senescence of articular chondrocytes

Objective To study whether IL-1β, a catabolic factor of cartilage metabolism, induces premature senescence of articular chondrocytes, and whether caveolin-1 mediates IL-1β-induced cellular senescence. Methods Cultured human articular chondrocytes were stimulated with 10 ng/ml IL-1β. Cellular senescent phenotypes were analyzed by cellular morphology, cell growth arrest (flow cytometry), telomere erosion (Southern blotting), life span (population doublings), and specific senescence-associated β-galac-tosidase (SA-β-Gal) activity. Expression level of caveolin-1 was modulated by anti-sense oligunucleotide or transfection of caveolin-1 gene. Caveolin-1 protein was analyzed by Western blotting. Results Incubation of chondrocytes with IL-1β markedly increase the percentage of cells in G0/G1 phase and reduce the percentage in S phase. Single stimulation with IL-1β enables chondrocytes to become big and flat, and SA-β-Gal activity in chondrocytes is enhanced. Repeated stimulation with IL-Iβ resulted in accelerats erosion of mean telomere length, and shortens life span. Down-regulation of caveolin-1 with anti-sense oligonucleotide significantly inhibits the features of chondrocytes senescence induced by IL-1β. In contrast, caveolin-1 overexpreasion enhanced SA-β-Gal activity in the chondrocytes. Conclusion IL-1β induces features of stress-induced premature senescence and telemere-dependent replicative senescence of articular chondrocytes, which is mediated by caveolin-1. These data suggest that IL-1β induces premature senescence of articular chondro-cytes by upregulation of caveolin-1, which facilitates the development of osteoarthritis.     

Interleukin-1β induced premature senescence of articular chondrocytes

Objective To study whether IL-1β, a catabolic factor of cartilage metabolism, induces premature senescence of articular chondrocytes, and whether caveolin-1 mediates IL-1β-induced cellular senescence. Methods Cultured human articular chondrocytes were stimulated with 10 ng/ml IL-1β. Cellular senescent phenotypes were analyzed by cellular morphology, cell growth arrest (flow cytometry), telomere erosion (Southern blotting), life span (population doublings), and specific senescence-associated β-galac-tosidase (SA-β-Gal) activity. Expression level of caveolin-1 was modulated by anti-sense oligunucleotide or transfection of caveolin-1 gene. Caveolin-1 protein was analyzed by Western blotting. Results Incubation of chondrocytes with IL-1β markedly increase the percentage of cells in G0/G1 phase and reduce the percentage in S phase. Single stimulation with IL-1β enables chondrocytes to become big and flat, and SA-β-Gal activity in chondrocytes is enhanced. Repeated stimulation with IL-Iβ resulted in accelerats erosion of mean telomere length, and shortens life span. Down-regulation of caveolin-1 with anti-sense oligonucleotide significantly inhibits the features of chondrocytes senescence induced by IL-1β. In contrast, caveolin-1 overexpreasion enhanced SA-β-Gal activity in the chondrocytes. Conclusion IL-1β induces features of stress-induced premature senescence and telemere-dependent replicative senescence of articular chondrocytes, which is mediated by caveolin-1. These data suggest that IL-1β induces premature senescence of articular chondro-cytes by upregulation of caveolin-1, which facilitates the development of osteoarthritis.     

Ventricular premature contractions. Which should be treated?

The treatment of ventricular premature contractions (VPCs) is based on two factors: bothersome symptoms from which the patient desires relief and the association of ectopic ventricular beats with sudden cardiac death. The sudden death risk related to ventricular ectopic beats is real, but appears to be a function of the frequency or pattern in which they occur plus the presence of underlying heart disease. A serious risk exists when frequent, multifocal, successive, or R-on-T-type VPCs occur in a patient monitored late after a fresh myocardial infarction, particularly if left ventricular failure is also present. Current data have been used to formulate levels of risk for sudden cardiac death on the basis of ventricular ectopic beats, which in turn provides a reasonable basis for the treatment of asymptomatic ventricular ectopy.     

Does hereditary metabolic disease modulate senescence and ageing?

Hereditary metabolic diseases in the context of evolutionary biology elicit interesting questions about ageing and senescence: Will persons successfully treated for inborn errors of metabolism, age and die prematurely because of compromised longevity? Because some unhealthy longevity has its origins in germline and somatic mutational processes, and in an inability to withstand metabolic stress, are there lessons to be learned about senescence from hereditary metabolic disease? Why are ageing, senescence and death necessary for Homo sapiens and how do they happen? These questions form the theme upon which several variations are played during the course of this essay. The theory of the disposable soma recognizes genomic and environmental events, well-seasoned by Chance, as determinants of ageing and senescence. Together, they cause the somatic damage that results in death. Genomics will reveal genes involved in longevity, both healthy and unhealthy. There will be schedules of gene expression behind our life-history traits. As in the field of hereditary metabolic disease, analogous genetic enquiries about ageing can be formulated. For example, how will heterozygotes age? Will association studies in centenarians reveal 'longevity genes'? Will disparate longevity in sib pairs reveal genetic factors? If there are 'ageing' mutations, of what types and with what effects? Will these initiatives lead to healthier longevity? A deeper question yet remains: why has human biology invested so greatly in grandparenthood?     

Can we say that senescent cells cause ageing?

Replicative senescence, the irreversible loss of proliferative capacity, is a common feature of somatic cells derived from many different species. The molecular mechanisms controlling senescence in mammals, and especially in humans, have now been substantively elucidated. However, to date, attempts to link the senescence of cells with the ageing of the organisms they comprise has not met with any similar degree of success, largely due to a lack of systematic investigation and the absence of the necessary biochemical tools. This review will summarise current data linking replicative senescence and organismal ageing. It will also suggest some essential tests of the cell senescence hypothesis and some necessary ground work which must be carried out before such tests can be fruitfully performed. It will not discuss the detailed molecular 'clockwork' controlling the decision to exit the cell cycle irreversibly because this is covered by other authors in this special issue.