LIVING WITH THE EARTH
to:
1. Discuss and define the concepts of environment and disease.
2. List and explain the factors influencing environmental disease including infectious disease, physical and chemical injury, ionizing radiation, developmental disease, neoplastic disease, and nutritional disease.
ENVIRONMENTAL DISEASE – Moore
Objectives for this Chapter
3. Explain the process of genetic replication in mammalian cells. List the major genetic components and discuss their primary actions and features.
4. Describe and discuss the major mechanisms of developmental and genetic diseases.
ENVIRONMENTAL DISEASE – Moore
Objectives for this Chapter
5.Describe and provide a schematic of the new processes in recombinant-DNA and genetic screening techniques.
6. Discuss and describe the new concepts on the origins of cancer, risk factors, and current trends.
ENVIRONMENTAL DISEASE – Moore
LIVING WITH THE EARTH
ENVIRONMENTAL DISEASE
Introduction
We continue to manufacture and disperse billions of tons of over 70,000 potentially toxic chemicals into the biosphere without regard for nature or an appreciation of the danger that these chemicals can bring to our earth or to us.
ENVIRONMENTAL DISEASE – Moore
LIVING WITH THE EARTH
ENVIRONMENTAL DISEASE
Introduction
Love Canal: Declared an emergency in 1978
Times Beach Missouri: Dioxin contamination discovered in 1982
ENVIRONMENTAL DISEASE – Moore
LIVING WITH THE EARTH
ENVIRONMENTAL DISEASE
Introduction
Carcinogen
Any chemical known to cause cancer.
Nearly 90 percent of cancers can be traced to an environmental cause and so may be largely preventable.
ENVIRONMENTAL DISEASE – Moore
What are the messages given through the public media about toxic chemicals?
Exposure to toxic chemicals have dramatically increased the risk of cancer.
Common household and agricultural chemicals are causing many human diseases and death.
ENVIRONMENTAL DISEASE – Moore
What are the messages given through the public media about toxic chemicals?
Polluted air and water are major sources of disease risk.
Environmental chemicals are interfering with the reproductive process in humans and producing harmful effects in the fetus and young children.
ENVIRONMENTAL DISEASE – Moore
Defining the Term Environment in Relation to Disease (Cancer)
Environment
Personal and cultural behavior including smoking, diet, alcohol consumption, sexual and reproductive patterns, workplace, infections, food additives, and pollution along with the strictly physical environment.
ENVIRONMENTAL DISEASE – Moore
Some of the Major Factors associated with Cancer
(Fig. 4.1)
Diet
Tobacco
Infection
Sexual behavior
Occupation
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Fig. 4.1
Adapted from Morbidity and Mortality Weekly Report. 15
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Pollution
Pollution may be defined as the presence of a foreign substance – organic, inorganic, radiological or biological – that tends to degrade the quality of the environment so as to create a health hazard.
ENVIRONMENTAL DISEASE – Moore
Defining Disease
A definite pathological process having a characteristic set of signs and symptoms which are detrimental to the well-being of the individual.
ENVIRONMENTAL DISEASE – Moore
Disease Terminology
Endemic
Diseases that already exist in a community where it is maintained in a low but constant incidence.
Epidemic
Marked increase in incidence of disease within limited area affecting ever-increasing number of people
ENVIRONMENTAL DISEASE – Moore
Disease Terminology
Pandemic
An epidemic spread throughout the world, as in the case of various outbreaks of influenza.
ENVIRONMENTAL DISEASE – Moore
Disease Terminology
Acute Disease
Having a rapid onset, is usually self-limiting, and are of relatively short duration.
Chronic Disease
Having a slow onset and lasting for extended period of time. (i.e. cancer, emphysema, some forms of heart disease, or AIDs)
ENVIRONMENTAL DISEASE – Moore
Defining Disease
Infectious Disease
Infectious diseases result from the pathologic process occurring when a microbial agent invades the body.
ENVIRONMENTAL DISEASE – Moore
Infectious Disease
Reservoirs
Sources of disease which can be living organisms or inanimate objects that provide the conditions where the organisms may survive, multiply, and also provide the conditions necessary for transmission.
ENVIRONMENTAL DISEASE – Moore
Infectious Disease
Carriers
People who may or may not exhibit symptoms, but harbor and transmit the disease organisms.
Zoonoses
Diseases that are spread from animals to humans, such as Lyme Disease.
ENVIRONMENTAL DISEASE – Moore
Infectious Disease
Major Routes of Infection
Contact
Vehicles
Vectors
ENVIRONMENTAL DISEASE – Moore
Major Routes of infection
Contact
Direct Contact Transmission (person-to-person)
Indirect Contact Transmission (cups, needles)
Droplet Infections (sneezing, coughing-droplets travel less than one meter)
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Major Routes of infection
Vehicle
Disease agents that are transmitted by various media such as air, water, food, intravenous fluids or blood, and drugs.
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Major Routes of infection
Vectors
Animals that carry pathogens from one host to another, either from another human that is infected or from an infected animal.
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Major Routes of infection
Vectors
Mechanical Transmission (foot pads)
Biological Transmission (biting insects and agent reproduces in vector)
Types of Hosts
Definitive Host (sexual cycle of disease agent takes place in definitive host – mosquito for malaria)
Intermediate Host (asexual cycle – humans for malaria)
ENVIRONMENTAL DISEASE – Moore
Physical and Chemical Injury
Physical Injuries include:
Mechanical Injury
Thermal Injury
Ionizing Radiation
ENVIRONMENTAL DISEASE – Moore
Physical and Chemical Injury
Major mechanisms for chemical Injury are:
Interference with enzyme activity
Directly combining with some cell component other than enzymes
Producing a secondary action in which a chemical causes the release or formation of a more harmful substance
ENVIRONMENTAL DISEASE – Moore
Developmental Disease
Every individual within each species is very much a representation of the information contained in the genome together with the expression of those genes in the development of that individual.
ENVIRONMENTAL DISEASE – Moore
Developmental Disease
Developmental disease occurs when faults or mistakes occur within the genes (or chromosomes), or stages in development of the fetus are disturbed.
ENVIRONMENTAL DISEASE – Moore
Developmental Disease
Major Categories of genetic disease include:
Single gene defects
Cytogenic defects
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Developmental Disease
Cytogenic Defects are:
Abnormalities in the number or structure of chromosomes
Teratologic Defects are:
Defects which arise during the embryonic period of development. Causative factors are usually not genetic but from exposure to chemicals or radiation (teratogens)
ENVIRONMENTAL DISEASE – Moore
Neoplastic Disease
Neoplasia
The new and uncontrolled growth of abnormal tissue from the transformation of normal body cells.
Tumors
The growth of cells as a result of neoplasia, also called a neoplasm.
Tumors may be malignant or benign.
ENVIRONMENTAL DISEASE – Moore
Malignant Tumors
Exogenous Factors-arising from the environment
Habits (tobacco use, poor nutrition, alcohol use, sexual and reproductive activities)
Ionizing radiation
Chemical exposure
Environment (socio-economic, geographical, and occupational)
Oncogenic viruses
ENVIRONMENTAL DISEASE – Moore
Malignant Tumors
Endogenous Factors-originating from within the body
Gender
Age
Hormonal imbalance
Impaired immune system
Genetic predisposition
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Nutritional Disease
Malnutrition, as a consequence of inadequate diet, is often associated with ignorance and poverty which are manifestations of a weakened society.
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Nutritional Disease
Kwashiorkor
Caused by a lack of protein in children 1-3 years old.
Marasmus
Caused by lack of food in children one year of age.
Scurvy
Caused by the lack of vitamin C.
ENVIRONMENTAL DISEASE – Moore
Environmental Disease
Any pathologic process having a characteristic set of signs and symptoms which are detrimental to the well-being of the individual and are the consequence of external factors, including exposure to physical or chemical agents, poor nutrition, and social or cultural behaviors.
ENVIRONMENTAL DISEASE – Moore
THE ROLE OF GENETICS IN DISEASE
Structure and Function
This thread of life is deoxyribonucleic acid (DNA), a spiral, staircase-shaped molecule over 3 billion steps long compressed in the nucleus of living cells.
The storage and transcription of biological information occurs within DNA which has the power to express that biological information in the form of proteins.
ENVIRONMENTAL DISEASE – Moore
Structure and Function
DNA is located within the cell nucleus of each of the human body’s 100 trillion cells (except mature red blood cells) (Fig. 4-2).
Each nucleus contains 46 chromosomes arranged in 23 homologous pairs.
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Fig. 4-2
Adapted from Elmer-Dewitt. 20
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Structure and Function of DNA
DNA is a very long, thread-like molecule which is formed by four recurring subunits called mononucleotides.
Nucleotides are identical and attached to each other in a long chain by phosphodiester links between carbon atoms in each molecule (Fig. 4-3).
ENVIRONMENTAL DISEASE – Moore
Fig. 4.3
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Structure and Function of DNA
Four different recurring mononucleotides are the base elements of the DNA coding system (Fig. 4-4).
Adenine and Guanine (purines)
Thymine and cytosine (pyrimidines)
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Structure and Function of DNA
Pair nucleotide bases fit together in a precise way, held together by hydrogen bonds between the base pairs and by hydrophobic bonding (Fig. 4-4).
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Fig. 4.4
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Replication
Dividing cells provide each daughter cell with one complementary strand of the parent DNA and then synthesize a complementary strand to produce double-stranded DNA.
ENVIRONMENTAL DISEASE – Moore
Structure and Function of DNA
Proteins
Proteins are composed of specific sequences of amino acids linked by peptide bonds
Enzymes are proteins
Proteins that interact with a substrate much like a key in a lock to catalyze the formation of a new molecule or product.
ENVIRONMENTAL DISEASE – Moore
Protein Biosynthesis
DNA must first be transcribed to another molecule called messenger RNA or mRNA before it can reach the ribosomes outside of the cell.
ENVIRONMENTAL DISEASE – Moore
Protein Biosynthesis
Codons
A group of 3 nucleotide bases which specifies the position of one amino acid in a protein molecule.
Anticodons
The recognition site for specific codon triplet (Fig. 4-5).
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Fig. 4-5
Adapted from Lehninger. 21
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Diseases of Genetics and Development
Genetic Abnormalities
Mutation
A change in the nucleotide base sequence of DNA.
ENVIRONMENTAL DISEASE – Moore