MCB 135K Discussion Monday, January 29, 2007 GSI: Ryan Klimczak

Information GSI: Ryan Klimczak Review sessions will be held prior to each exam –Time and locations TBA

Discussion Material 1.Course Introduction 2.Demography 3.Comparative Aging 4.Delaying the Degenerative Diseases of Aging 5.Theories of Aging

Course Introduction Age Related Terminology –Aging –Geriatrics –Gerontology –Senescence –Biomarkers –Life-Span –Average Life Span –Life Expectancy –Active Life Expectancy –Longevity –Maximum Life Span 1.Increased length of lifespan & increased number of the elderly in the human population 2.Increased proportion of persons aged 65+ in the population as compared to those aged This change in the human population is acknowledged by the industries and professions 4.Need to better educate the population in healthy habits 5.Need to support research in biomedicine 6.Points 4 and 5 must take into consideration the entire life cycle as our health today depends on our health yesterday and will influence our health tomorrow

Divisions of the Lifespan Prenatal Life Ovum: Fertilization - end 1st week Embryo: 2nd-8th week Fetus: 3rd-10 lunar month Neonatal Period Newborn: end of 2nd week Infancy: 3rd week-1st year Childhood: 2-15 years Adolescence: 6 yrs after puberty Postnatal Life Adulthood Prime & transition (20-65 yrs) Old age & senescence (65 yrs+)

Life expectancy and infant mortality throughout human history Life expectancy Infant mortality rate at birth (years) (per 1000 live births) Prehistoric Sweden, 1750s37210 India, 1880s25230 U. S., France, Japan,

Questions Lecture 1 - The Journey of Life  What is the primary reason that life span has doubled since ~1900?  What was the average life span in prehistoric times, ~1900, now?  When does the process of aging begin?  Why doesn’t the degree of pathophysiology correlate directly with age?  What is the reason for the increase in average life span from ~ ? From present?

Demography Statistical study of human populations: –Size and density distribution Vital Statistics: –epidemiology: Births, deaths, diseases

Life expectancy at birth by sex, France

Proportion of population aged 0-14 versus 65+(In Italy)

Centenarians Generally good health –Escapers –Late onset of disease –Early disease that was overcome SSC (Semi-Super) –105+ SC (Super) –110+ Possible role of IGF-1 Receptor Oldest Female –122 years –Jeanne Calment Oldest Male –115 years –Christian Mortensen

Questions Lecture 2 - Demography of Aging  What is epidemiology?  How long was the longest recorded human life span, male and female?  What are some probable causes that favor longevity in women?  What does the concordance between centenarians and the increased likelihood of prolonged lifespan in their offspring suggest?  What physiological characteristics are generally observed in individuals who live past the age of 100?

Comparative and Differential Aging Aging amongst different animal species Aging differences between people of the same species Chronological vs. Physiological Age

Figure 3.2: Comparison of the relationship of brain weight to life span in vertebrates

Figure 3.1: Comparative Maximum Life Spans **Detailed discussion of figure in the legend, pg. 26

Among invertebrates, the most used models have been the fly (Drosophila melanogaster) and the nematode (C. elegans) Suppression of the receptor for insulin/IGF hormone will produce a mutant nematode that will live 6x longer than corresponding controls and be more resistant to all stress. C. Elegans 2 week lifespan hermaphrodite 19,000 genes 959 cells Examples of ways in which environment influences the genome (cont.)

Kenyon et al. Science, 2003

Figure 3.3: The heterogeneity of the elderly population as illustrated by scores in a hypothetical test.

Transcriptional Profile of Aging Related Genes in the Human Brain Rodwell et al. 2004

Recent approaches challenge the inevitability of functionpathology by grouping the aging processes into three categories: 1.Aging with disease and disability 2.Usual aging, with absence of overt pathology but presence of some declines in function 3.Successful or healthy aging, with no pathology and little or no functional loss

Assessment of Physiological Age in Humans Physiological age depends on Physiologic competence: good to optimal function of all body systems & Health status: absence of disease Physiological age may or may not coincide with chronological age

Laboratory Values in Old Age: 1.Most values unchanged (e.g. hepatic, coagulation, electrolytes, renal, thyroid, blood count, etc.) 2.Some values decreased (e.g. HDL in women) 3.Some values increased (e.g. LDL in men, glucose) **See Table 3.2**

Question Comparative and Differential Aging  How well does chronological age correlate with physiological age? In young versus old individuals?  What parameters do you use to define "healthy" aging?  What sorts of behavior favor a long life span?  What are the mechanisms or traits associated with "successful" aging?  What is aging vs. usual aging vs. successful aging?  Discuss the idea that women have more disability than men.

Delaying the Degenerative Diseases of Aging Oxidative DNA damage as a function of aging Mitochondrial decay and aging ALCAR and Lipoic Acid, potential supplements to extend lifespan/enhance quality of life Nutrient deficiency and aging

Estimated oxidative DNA adducts per rat liver cell 0 Old (26-mo) Young (4-mo) 70,000 60,000 50,000 40,000 30,000 20,000 10,000 24,000 67,000

Young Old Mitochondria in hippocampal neurons Electron Microscopy Images

Cardiolipin Levels in 3 and 24 Month Old Rat Hepatocytes Cardiolipin ( µ g per 10 6 Cells) YoungOld 10 ** Cardiolipin (diphosphatidyl glycerol) is an important component of the mitochondrial membrane, typically present in metabolically active cells of the heart and skeletal muscle. It has also been observed in certain bacterial membranes. It serves as an insulator and stabilizes the activity of protein complexes important to the electron transport chain.

R123 Fluorescence in old and young rat hepatocytes Fluorescence/cell Normal cell number 0.03 Young Old 11 Rhodamine A popular green fluorescent mitochondrial dye that stains mitochondria in living cells in a membrane potential-dependent fashion. Widely used in flow cytometry studies involving mitochondrial membrane potential.

Mitochondria from old rats compared to those from young rats: 1) Lower Cardiolipin 2) Lower Membrane Potential 3) Lower Oxygen Utilization 4) Increased Oxidant Leakage

L-Carnitine/Acetyl-L-Carnitine (ALCAR) Mediates the ratio of acetyl-CoA/CoA Decreases with age in plasma and in brain Improves cognitive function in rats 12 Transports long-chain fatty acids into mitochondria Removes short- and medium-chain fatty acids that accumulate

WIKIPEDIA DEFINITION: Carnitine transports long-chain acyl groups from fatty acids into the mitochondrial matrix so they can be oxidized for energy. Fatty acids must be activated before binding to the carnitine molecule to form acyl- carnitine. The free fatty acid in the cytosol is attached with a thioester bond to coenzyme A (CoA). This reaction is catalyzed by the enzyme fatty acyl-CoA synthetase and driven to completion by inorganic pyrophosphatase. The acyl group on CoA can now be transferred to carnitine and the resulting acyl-carnitine transported into the mitochondrial matrix. This occurs via a series of similar steps: -Acyl-CoA is conjugated to carnitine by carnitine acyltransferase (palmitoyltransferase) I located on the outer mitochondrial membrane -Acyl-carnitine is shuttled inside by a translocase -Acyl-carnitine is converted to acyl-CoA by carnitine acyltransferase (palmitoyltransferase) II located on the inner mitochondrial membrane. The liberated carnitine returns to the cytosol.

R-  -Lipoic Acid (LA) in mitochondria LA reduced to dihydrolipoic acid, a potent antioxidant, & chelator of Fe & Cu Coenzyme of pyruvate and  -ketoglutarate dehydrogenases, involved in the citric acid cycle Involved with carbohydrate utilization for ATP production, shown to increase the cellular uptake of glucose in vitro by recruiting a glucose transporter to the cellular membrane 15

Effects of ALCAR and LA supplements ALCAR increases Cardiolipin levels, increases mitochondrial membrane potential ALCAR/LA reduce the amount of mitochondrial DNA adduct levels in old rats -increases ambulatory activity of old rats -enhances immune function -improves spatial memory/ mental acuity Clinical trials in humans suggest LA can improve neuropathic symptoms and deficits in diabetic patients

Micronutrient Deficiency Heme Deficit Complex IV Deficit Oxidative Stress DNA Damag e Early Senescen ce Pyridoxine [+][+]++ Zinc +## Riboflavin Iron ++[+] Copper [+] Biotin Lipoic Acid [+] Pantothenate [+] Micronutrient deficiency and heme synthesis in human cell culture + = Atamna/Ames, ++Askree /Ames, #Ho/Ames [+] Literature

Calcium Deficiency Vitamin B12 Fenech: chromosome breaks Fenech: Chromosome breaks Lipkin: colon cancer mice Folate Deficiency Selenium MacGregor/Ames/Fenech: chromosome Rao: DNA damage breaks mice/humans Combs/Trumbo: Cancer humans Willett: epi colon cancer humans Vitamin D Deficiency Omega-3 FA Garland: epi colorectal cancer humans Denkins: Cancer Magnesium Deficiency Niacin Bell: chromosome breaks humans Kirkland/Depeint: DNA damage Larsson: epi colorectal cancer humans Zinc Deficiency Choline Fong: esophageal cancer humans/rodents da Costa: DNA damage in humans Potassium Deficiency Chang: Cardiovascular Disease

Questions Discuss the correlation between DNA Oxidative Damage and aging. How may ALCAR or LA mediate their potential effects? What are the effects of aging on mitochondria and mitochondrial function? List some nutrient deficiencies and describe their potential contribution to accelerated aging.

Theories of Aging

Molecular Codon restriction Somatic mutation Error catastrophe Gene regulation. Dysdifferentiation Classification and brief description of main theories of aging Cellular Wear-and-tear Free radical accumulation Apoptosis System Rate-of-living Neuroendocrine Immunologic Evolutionary Disposable Soma Antagonistic Pleiotropy Mutation Accumulation

Evolutionary Theories of Aging Disposable Soma - Somatic cells are maintained only to ensure continued reproductive success, following reproduction the soma is disposable. (life span theory) Antagonistic Pleiotropy - Genes that are beneficial at younger ages are deleterious at older ages. ( Pleiotropism = The control by a single gene of several distinct and seemingly unrelated phenotypic effects) Mutation Accumulation - Mutations that affect health at older ages are not selected against (no strong evidence).

Evolution in the Laboratory young flies selected Normal % Surviving Age in Days - Early adult fecundity increased * antagonistic pleiotropy Offspring of “young” flies are selected - Reproductive period extended - Stress resistant, -super flies - Early adult fecundity reduced *antagonistic pleiotropy Offspring of “old” flies are selected

Molecular Theories of Aging Codon restriction Fidelity and/or accuracy of mRNA message translation is impaired with aging due to cell inability to decode the triple codons (bases) in mRNA molecules Somatic mutation Type of stochastic* theory of aging that assumes that an accumulation of environmental insults eventually reaches a level incompatible with life, primarily because of genetic damage. Error catastrophe Errors in information transfer due to alterations in RNA polymerase and tRNA synthetase may increase with age resulting in increased production of abnormal proteins Gene regulation Aging is caused by changes in the expression of genes regulating both development and aging Dysdifferentiation Gradual accumulation of random molecular damage impairs regulation of gene expression * Involving Random Chance

Cellular Theories of Aging Wear-and-tear Intrinsic and extrinsic factors influence life span Free radical accumulation Oxidative metabolism produces free radicals which are highly reactive and thus damages DNA and/or proteins and thus degrades the system structure and function. Apoptosis Process of systematically dismantling key cellular components as the outcome of a programmed intracellular cascade of genetically determined steps.

System Theories of Aging Rate-of-living An old theory that assumes that there is a certain number of calories or heart beats allotted to an individuals and the faster these are used the shorter the life. Neuroendocrine Alterations in either the number or the sensitivity of various neuroendocrine receptors gives rise to homeostatic or homeodynamcis changes that results in senescence. Immunologic Immune system reduces its defenses against antigens and thus results in an increasing incidence of infections and autoimmune diseases.

Free Radical Theory of Aging The free-radical theory of aging (FRTA) is that organisms age because protein, lipid and nucleic acids (DNA, RNA) accumulate free radical damage with the passage of time. Free radical attack on protein, lipid and nucleic acids leads to a reduction in their respective function, thereby decreasing cell function, then organ function, and finally, organismal function.agefree radicaltime Any element that has an unpaired electron in its outermost shell is considered to possess a "free radical”. In biochemistry, the free radicals of interest are often referred to as reactive oxygen species (ROS) because the most biologically significant free radicals are oxygen-centered. But not all free radicals are ROS and not all ROS are free radicals.biochemistryreactive oxygen species

Questions: Describe the genetic changes that may underlie the short lived and long-lived phenotypes in the evolutionary fly studies. What is a real world example that demonstrates the disposable soma theory? How can the lifespan extending effects of caloric restriction be explained by the various theories of aging?