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119 Cards in this Set
- Front
- Back
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Survival Data
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quantitative measurements of duration
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Survival Analysis
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a collection of statistical methods designed to summarize and extract information from survival data
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Reliability Engineering
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type of survival analysis used to predict failures of manufactured products
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Biodemographers
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use survival analysis to quantify age-specific patterns of death, to predict population trends, and to determine the efficacy of clinical treatments
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Longitudinal Data
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come from long term observation of populations
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Cross-sectional Data
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based on relatively brief periods of observation
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Cohort
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a population of organisms that are all approximately the same age
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Prospective Clinical Study
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goal is to compare patient groups that receive different medical treatments
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Censored Data
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Incomplete data, common in clinical trials
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Prospective Survival Study
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the survival experiences of past human cohorts are reconstructed from historical records of births and deaths
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Uncensored Data
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complete measurements of lifespan with a defined starting point, such as birth, and ending with death
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Life Table
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structure for organizing survival data, clarify the relationship between deaths rates and age
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John Graunt
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father of demography, credited with invention of life tables
used them to study death in the 1660s (the Great Fire of London and the bubonic plague) |
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x
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age or age-class
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d-sub-x
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number of deaths in age-class x
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N-sub-x
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number alive at the start of age-class x
(previous age-class population) - (number of deaths) |
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l-sub-x
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survivorship at age x
(current population)/(initial population) |
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q-sub-x
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age-specific mortality at age x
(number of deaths)/(current population) |
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e-sub-x
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life expectancy at age x
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Cohort Life Table
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used to analyze longitudinal data
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Current Life Table
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used to analyze cross-sectional data
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Actuarial Life Table
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observations are organized into discrete time units that are under the control of the experimenter
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Kaplan-Meier Life Table
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survival time is treated as a continuous variable
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Heat Shock Proteins (hsp's)
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gene products synthesized by a wide variety of organisms in response to acute environmental stresses
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What type of data was the collected in the Drosophila melanogaster hsp experiment?
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Longitudinal and uncensored
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What type of data is collected by the U.S. Census Bureau?
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cross-sectional and actuarial
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Random Environmental Variation
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there is significant uncontrolled variation that affects death rates in experimental populations; there is substantial intrinsic variability (P=G+E)
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Design of Survival Studies
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no single design satisfies all needs or applies to all species under investigation
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Sample Size Considerations
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size of sample population needed to collect accurate data varies with variable being evaluated
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Cohort History and Age-Specific Effects
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survivorship at age x reflects the entire survival history of a cohort up until age x; early events may distort later data
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4 Life Table Lessons
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1. Random experimental variation
2. Design of survival studies 3. Sample size considerations 4. Cohort history and age-specific effects |
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mu-sub-x
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force of mortality or 'hazard'; age-dependent death rate
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Benjamin Gompertz
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pioneer of actuarial science; death is the consequence of chance and deterioration, or an increased inability to withstand destruction
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Hazard
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a theoretical quantity that describes the instantaneous risk of death
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MRDT
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Mortality Rate Doubling Time
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Wall of Death
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with exponential increase the risk in old age becomes very large, there is almost no chance of survival after a certain point, there is an upper limit
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James Fries
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argues average life spans have increased, but maximum life spans have not
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Rectangularization of Survivorship or Compression of Mortality
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almost all individuals will live to an advanced age, then in a brief period, almost all will die
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Oldest-old
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humans over the age of 85
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Mortality Plateau
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mortality trajectories; the mortality curve is plotted on a semi-log scale
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Rocking Chair Hypothesis
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proposes that mortality rates increase slowly or not at all in old age because older organisms suffer physiological deterioration at a slower rate than the younger organisms because of less risky behavior
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Less Risky Behavior
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less effort in mating, reproduction, defense of territory, and other high-energy and high-risk activities of youth
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Heterogeneity Hypothesis
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as the population ages, its composition changes and becomes increasingly biased toward the more robust individuals
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Demographic Selection
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the process of selective elimination of weaker individuals within an aging cohort
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The 'Dead Cat' Model
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death occurs when there is an accumulation of damage over time; mortality curve increases exponentially early in life (Gompertz) but the increase slows later in life producing a mortality plateau
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Amino Acid
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chemical building block of proteins
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Antioxidants
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compounds that neutralize oxygen radicals (ex: SOD, catalase, vitamin C)
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Anti-proliferative Genes
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genes that inhibit cell division ot proliferation; can act as tumor suppressor genes
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Base
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part of a nucleotide (adenine, thymine, cytosine, guanine, uracil)
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Biomarkers
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biological changes that characterize the aging process (none have been identified in humans)
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Caloric Restriction
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experimental intervention being studied to determine its impact on longevity; lifespans of lab animals have been extended
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Centenarian
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a person who has lived at least 100 years
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Chromosome
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a cellular structure containing genes; composed of DNA and proteins; humans have 23 pairs of chromosomes in each body cell
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Cytokines
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proteins that are secreted by cells and regulate the behavior of other cells by binding to receptors on their surfaces
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DNA
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deoxyribonucleic acid; molecule containing genetic code; made up of nucleotides, each containing one base, one phosphate molecule, and the sugar molecule deoxyribose
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Enzyme
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a protein that promotes a specific biochemical reaction in the body without itself being permanently changed or destroyed
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Fibroblast
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one of the major cell types found in skin; used to study aging at the cellular level
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Free Radicals
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molecules with unpaired electrons that react readily with other molecules
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Oxygen-free Radicals
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produced during metabolism; damage cells and may be responsible for aging in tissues and organs
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Gene
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segment of DNA that contains the code for a specific protein
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Gene Expression
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process by which the information contained in genes in transcribed and translated into proteins
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Glycation
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process by which glucose links with proteins and causes these proteins to bind together; can result in stiffening of tissues
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Hayflick Limit
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finite number of divisions a cell is capable of when cultured in a lab setting (in vitro)
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Interleukins
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type of cytokine involved in regulation of immune function
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Lymphocytes
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small white blood cells that are important to the immune system
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Maximum Lifespan
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the greatest age reached by any member of a given species
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Mean Lifespan
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the average number of years that members of a species live; aka life expectancy
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Mitochondria
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cell organelles that metabolize glucose and other sugars to produce biochemical energy; also contain DNA which is damaged by the high levels of free radicals produced by this process
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Mitosis
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process of replicating DNA, dividing it into two equal parts to generate identical daughter cells
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Nucleotide
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building block of DNA or RNA; include one base, one phosphate molecule, and one sugar molecule (deoxyribose or ribose)
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Photoaging
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process initiated by sunlight through which the skin becomes drier and loses elasticity
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Proliferative Genes
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genes that promote cell division or proliferation; can act as oncogenes
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Oncogenes
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genes that promote cancer growth
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Proteins
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molecules composed of amino acids; essential for all life processes
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Replicative Senescence
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the stage at which a cell has permanently stopped dividing
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RNA
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ribonucleic acid; carries out DNA's instructions for making proteins; three types: messenger RNA, transfer RNA, ribosomal RNA
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Telomeres
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repeated short DNA sequences occurring at the end of chromosomes; telomeres shorten each time a cell divides
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Tumor Suppressor Genes
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genes that inhibit cell division or proliferation
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NIA
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National Institue on Aging
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NIH
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National Institues of Health
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Gerontologist
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person that studies aging
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Programmed Theories
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aging follows a biological timetable
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Damage or Error Theories
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emphasize environmental assaults to our systems
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Programmed Longevity
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again is the result of the sequential switching on and off of certain genes (PROGRAMMED)
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Endocrine Theory
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biological clocks act through hormones to control the pace of aging (PROGRAMMED)
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Immunological Theory
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a programmed decline in immune system functions leads to increased vulnerability to infectious disease (PROGRAMMED)
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Wear and Tear Theory
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cells and tissues have vital parts that wear out (ERROR)
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Rate of Living Theory
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the greater an organism's rate of oxygen basal metabolism, the shorter it's life span (ERROR)
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Crosslinking Theory
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an accumulation of crosslinked proteins damages cells and tissues, slowing down bodily processes (ERROR)
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Free Radicals Theory
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accumulated damage caused by oxygen radicals causes cells to stop functioning (ERROR)
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Somatic DNA Damage Theory
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genetic mutations occur and accumulate with increasing age, causing cells to deteriorate and malfunction (ERROR)
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Silencing Gene
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a gene that 'turns off' other genes
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Gompertz Law
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risk of death grows exponentially
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Aging
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passage of time
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Senescence
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loss of vitality with increasing age, Wall of Death
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Medawar
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no senescence, no limits, larger cohorts=longer life spans
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4 Stages of Demographic Transition Model
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1: Pre-Modern - high birth, high death
2: Urban/Indus - high birth, lower death 3: Mature Ind - lower birth, low death 4: Past Ind - low birth, low death |
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What kind of data are Age Pyramids?
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cross-sectional
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How do I make an appt with Dr. Curtsinger?
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send an email and include three times that will work for me
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What is the biology of aging?
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integrative discipline, encompassing studies of molecules, genes, cells, tissues, organs, organisms, and populations
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INDY
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gene that can double the lifespan of fruit flies; I'm Not Dead Yet
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daf-2
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controls a special stage in the worm's (C. elegans) development called dauer formation; can double lifespan if activity of this gene is reduced and dauer is not formed
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Microarray
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tool which allows scientists to survey the expression of thousands of genes at once
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in vitro
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in a lab setting or in a test tube
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Antagonistic Pleiotropy
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concept that genes, which have beneficial effects early in life, can also have detri- mental effects later
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Mitochondria
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coverts oxygen to food and ATP
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Werner's Syndrome
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rare disease with features of premature aging; have a defect in one of their helicases, an enzyme that unwinds DNA
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Estrogen
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slows bone thinning
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Growth Hormone
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plays a role in body composition and muscle and bone strength
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Melatonin
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regulates various seasonal changes in the body
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Testosterone
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possible link to delay or prevention of frailty
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DHEA
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precursor to testosterone and estrogen
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What are two organ systems that have important roles in the aging process?
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endocrine system, immune system
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What are some examples of normal aging?
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heart muscle thickens, arteries stiffen, lung capacity declines, neural connection decline, kidneys decrease in efficiency, bladder capacity declines, lose muscle and body fat, bone mineral is lost, eyes lose ability to focus, higher frequencies become more difficult to hear
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B-cells
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mature in bone marrow and secrete anti-bodies in response to infectious agents
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T-cells
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develop in the thymus and develop into cytotoxic T-cells and helper T-cells
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Cytotoxic T-cells
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attack infected or damaged cells
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Helper T-cells
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produce lymphokins
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mu_sub_x
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instantaneous risk of death, a probability that cannot be greater than one
-ln(next population/current population) |
