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Questions and Answers
What is defined as the maximum age that can be attained by a species?
What is defined as the maximum age that can be attained by a species?
Which of the following is not associated with the wear and tear theory of aging?
Which of the following is not associated with the wear and tear theory of aging?
Which free radical is specifically identified as having a hydroxyl radical structure?
Which free radical is specifically identified as having a hydroxyl radical structure?
What percentage of the U.S. population is projected to be over 65 by the year 2030?
What percentage of the U.S. population is projected to be over 65 by the year 2030?
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Which type of antioxidant is intracellular?
Which type of antioxidant is intracellular?
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Which of the following correctly describes a characteristic of free radicals?
Which of the following correctly describes a characteristic of free radicals?
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What is a common cellular target of free radical damage?
What is a common cellular target of free radical damage?
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Which condition is considered a possible source of free radicals?
Which condition is considered a possible source of free radicals?
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What best describes the process of senescence?
What best describes the process of senescence?
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Which enzyme mentioned plays a role in the neutralization of superoxide radicals?
Which enzyme mentioned plays a role in the neutralization of superoxide radicals?
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Which system experiences a decrease in T cell function associated with aging?
Which system experiences a decrease in T cell function associated with aging?
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What change in the lungs is commonly observed with aging?
What change in the lungs is commonly observed with aging?
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What occurs to the kidneys as a result of aging?
What occurs to the kidneys as a result of aging?
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Which condition is characterized by accelerated aging with specific physical features?
Which condition is characterized by accelerated aging with specific physical features?
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Which of these is NOT a feature of normal aging?
Which of these is NOT a feature of normal aging?
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What change occurs to blood vessels in the cardiovascular system with aging?
What change occurs to blood vessels in the cardiovascular system with aging?
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What mental change is associated with aging?
What mental change is associated with aging?
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What is a common change in skin appearance due to aging?
What is a common change in skin appearance due to aging?
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In Progeria, which physical feature is notable?
In Progeria, which physical feature is notable?
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What effect does aging have on hormone production?
What effect does aging have on hormone production?
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What effect does increased free radical damage have on the elderly?
What effect does increased free radical damage have on the elderly?
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Which process leads to altered enzyme activity as people age?
Which process leads to altered enzyme activity as people age?
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What is a consequence of the error-catastrophe theory in ageing?
What is a consequence of the error-catastrophe theory in ageing?
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What role do telomeres play in programmed aging?
What role do telomeres play in programmed aging?
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Which of the following is NOT a proposed cause of cellular decline with age?
Which of the following is NOT a proposed cause of cellular decline with age?
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What is the average lifespan of a person with progeria?
What is the average lifespan of a person with progeria?
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What is the primary substance associated with cellular waste accumulation in the elderly?
What is the primary substance associated with cellular waste accumulation in the elderly?
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Which statement about gene mutations and aging is accurate?
Which statement about gene mutations and aging is accurate?
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Which condition is NOT associated with progeria?
Which condition is NOT associated with progeria?
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How do nerve conduction velocity percentages change from age 60 to 80?
How do nerve conduction velocity percentages change from age 60 to 80?
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What is the primary cause of death in individuals with progeria?
What is the primary cause of death in individuals with progeria?
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Which functional capacity experiences the most significant decline by age 80?
Which functional capacity experiences the most significant decline by age 80?
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Which of the following best describes calorie restriction?
Which of the following best describes calorie restriction?
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What factor influences the Hayflick limit in cellular division?
What factor influences the Hayflick limit in cellular division?
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Which company is focused on identifying genes responsible for longevity?
Which company is focused on identifying genes responsible for longevity?
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What effect does the SIR2 gene have in nematode worms when caloric intake is reduced?
What effect does the SIR2 gene have in nematode worms when caloric intake is reduced?
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What is the purpose of the pharmacological compound being researched by Centagenetix?
What is the purpose of the pharmacological compound being researched by Centagenetix?
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What happens to genetically engineered mice that cannot produce superoxide dismutase?
What happens to genetically engineered mice that cannot produce superoxide dismutase?
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Which change is NOT a benefit of calorie restriction?
Which change is NOT a benefit of calorie restriction?
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What is a common feature observed in progeria patients?
What is a common feature observed in progeria patients?
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Study Notes
Ageing: Theories and Disease
- Ageing is defined as a decreasing ability to survive
- Key factors of ageing include: reduced ability to work, increased susceptibility to major diseases, and a large health care commitment
- Life expectancy is the mean age of individuals at the time of death.
Ageing: Terminology
- Lifespan is the maximum age that a species can attain.
Estimates and Projections of the Total Population in the United States and the Percentage of Elderly, 1900-2030
- Data shows the total population and the percentage of people over 65 in the United States from 1900 to 2030. Projections are included.
Percentage of Elderly in the U.S. Population by Age Group
- Data shows the percentage of the population for age groups 65-74, 75-84, and 85 and above, from 1960 to 2040.
Features of Ageing
- Senescence
- Age-related disease
Senescence Changes
- Senescence may cause age-related disease
- Senescence may increase susceptibility to disease
Theories of Ageing: Wear and Tear
- Free radicals
- Glycation
- Waste products
- Error-catastrophe
Free Radical: Definition
- An atom or molecule that contains one or more unpaired electrons
Free Radicals: Nature
- High reactivity
- Short half-life
- Propagate chain reactions
Type of Free Radicals
- Hydroxyl radical (OH-)
- Superoxide radical (O2-)
- Nitric oxide (NO)
Sources of Free Radicals
- Phagocytic cells
- Ionising radiation
- Smoking
- Oxidation-reduction reactions
- Hyperglycaemia
Free Radicals Damage
- DNA/RNA damage
- Protein damage
- Enzyme damage
- Membrane lipid damage
- Cell damage
Antioxidant: Definition
- A substance that will delay or inhibit the oxidation of an oxidisable substrate
Types of Antioxidants
- Extracellular: Vitamin E
- Intracellular: Superoxide dismutase, catalase
Superoxide Dismutase: Action
- Superoxide dismutase converts superoxide radicals to hydrogen peroxide and oxygen. Catalase then converts hydrogen peroxide into water and oxygen.
Free Radicals in Ageing
- Increased free radical damage with age
- Decreased antioxidant defences with age
Free Radicals in Ageing: Biomolecules
- Damage to biomolecules may occur.
- Defense mechanisms like antioxidants aim to prevent or repair damage.
Free Radicals in Ageing: Outcomes
- Biomolecule damage can lead to cell death, aged cells, or cancer.
- This leads to a decline in tissue and organ function, as well as age-related pathologies, and in the end, death.
Protein Glycation
- The elderly are susceptible to protein glycation due to decreased glucose tolerance and increased rates of diabetes.
Glycation of a Protein
- Glycation involves the attachment of glucose to a protein. This forms a Schiff base, Amadori product, and eventually advanced glycation endproducts, or AGEs.
Effects of Glycation on Proteins
- Increased cross-linking
- Increased fluorescence
- Altered enzyme activity
- Altered immunogenicity
- Altered half-life
- Altered receptor recognition
Accumulation of Waste Products
- Lipofuscin is a lipid-rich pigment produced due to the byproducts of free radical peroxidation.
- Effects of lipofuscin are unknown
Error-Catastrophe Theory
- Abnormal proteins are produced due to DNA transcription and translation errors.
- Accumulation of abnormal proteins impairs cellular function.
Theories of Ageing: Genome Based
- Programmed ageing
- Mutations
Programmed Ageing
- Number of cell divisions is fixed (Hayflick limit)
- Limit not affected by external environment
- Cells can memorise undertaken divisions.
- Telomeres shorten, limiting cell division. Telomerase can extend cellular division.
Gene Mutations
- Errors in DNA replication that are not repaired affect cell viability.
- DNA repair systems decrease with age.
Multifactorial Nature of Ageing
- Ageing is influenced by genetics, lifestyle factors, and environment. These lead to a rate of ageing, which gives rise to age-related diseases.
Declines in Various Human Capacities With Age
- Data on various human capacities decline/reduction percentage with age, from 60 and 80 years old compared to 30.
Cellular Ageing
- Decline in mitochondrial activity
- Decline in oxidative phosphorylation
- Decline in DNA/RNA processes
- Decline in nutrient uptake
- Decline in chromosomal repair
- Accumulation of waste products
- Changes in organelle shapes
Immune System
- Decrease in antibody production
- Decline in T cell function
- Atrophy of thymus and
- Increased in autoimmune reactions
Skin
- Increased wrinkling
- Skin pigmentation
- Greying of hair
- Loss of hair
- Delayed wound healing
Lungs
- Decrease in lung size
- Decrease in lung elasticity
- Reduced gaseous exchange
- Reduced capacity for strenuous work
Cardiovascular System
- Increased rigidity of blood vessels
- Arterial calcification and hardening
- Increase in blood pressure
- Accumulation of fibrous tissue in heart muscle
- Reduced cardiac output
- Reduced blood supply to tissues
Kidneys
- Decrease in kidney weight/volume
- Loss and replacement of nephrons with scar tissue
- Reduced renal filtration rate
- Reduced elimination of waste
Liver
- Reduction in liver size and hepatocytes
- Decline in liver functions (e.g. drug detoxification)
Muscles
- Muscles undergo atrophy
- Decreased capacity for work
Endocrine System
- Decline in hormone production
- Decline in hormone receptors
Brain
- Loss in weight
- Loss of nerve cells
- Increase in amyloid deposition
- Accumulation of lipofuscin
Eye
- Decreased ability of lens to change shape
- Increased cross-linking and browning of lens protein
Body Composition
- Decrease in muscle mass
- Increase in total body fat
Progeria (Hutchinson-Gilford Syndrome)
- Disorder characterized by accelerated ageing.
- Affected children age approximately 10 times faster than a normal human being.
Progeria: Incidence
- Very rare
- Reported cases globally are few
- Reported cases across all history is also limited
Progeria: Aetiology
- Sporadic dominant mutation.
- Reduced life-span of cells
- Reduced DNA repair of damaged DNA.
Progeria: Clinical
- Thinning / wrinkling of skin
- Alopecia
- Loss of subcutaneous fat
- Prominent veins on the scalp
- Beak-like nose
- Characteristic squeeky voice
- Short stature
- Arthritis
- Osteoporosis
- Normal/high intelligence
- Delayed development
Progeria: Features compared to Ageing
- Presents with multiple characteristics across various bodily systems
- Presents with several physical features that distinguish it from the normal ageing pattern.
Progeria: Outlook
- Average lifespan is approximately 13 years
- Death often results from coronary heart disease or stroke
Progeria: Diagnosis
- Difficult due to rarity.
- Insidious onset
- Elevated urinary hyaluronic acid
Progeria: Management
- No cure for progeria
- Education/psychological support
- Medications to relieve symptoms of the condition
Calorie Restriction
- Only known method of slowing aging in mammals.
- Reduced calorie intake: extends lifespan and delays age related diseases.
Calorie Restriction: Examples
- Found effective in extending life spans in numerous species such as protozoa, spiders, water fleas, chickens, and rhesus monkeys.
Calorie Restriction: Effect
- Reduces age-associated mutations
- Reduces free radical damage
- Reduces advanced glycation endproducts
Anti-ageing Therapy
- Aim to make ourselves younger for longer, instead of ageing for longer.
Anti-ageing Therapy Companies
- Centagenetix
- Elixir
- Eukarion
- Alteon
- Geron Corporation
Centagenetix
- Seek genes responsible for longevity.
- Collect DNA from people with long lifespans, and identified a gene on chromosome 4
- Develops compounds to mimic proteins coded by genes.
Elixir
- Study nematode worms with multiple copies of genes SIR2. SIR2 enhances lifespan during caloric restriction.
- Identify longevity genes for anti-ageing medications.
Eukarion genetically engineering
- Mice engineered to lack superoxide dismutase
- Superoxide dismutase aids lifespan due to oxidative damage
Alteon
- Develop drugs to reduce AGEs (advanced glycation endproducts)
- Previous unsuccessful trial with aminoguanidine.
- Anti-glycation drugs
Geron Corporation
- Telomerase protects telomeres at the ends of chromosomes
- Drug that switches off telomerase in cancer cells.
- Drug that switches on telomerase to protect telomeres and extend lifespans.
Essential Reading
- Ahmed et al (2007): Biology of disease
- Taylor & Francis book, specific pages 515-530.
Conclusion
- Ageing, caused by wear and tear processes, is influenced by genes.
- Ageing leads to senescence and heightened susceptibility to diseases.
- Potential future anti-ageing therapies have positive influence.
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Description
Test your knowledge on the biological concepts related to aging, including theories, free radicals, and the demographics of aging populations. This quiz features questions about the physiological aspects and the role of antioxidants in cellular aging processes.
