BEDH Guide Flashcards
Benefits of Sun Exposure
Provides energy to the planet, primary biological importance is the process of photosynthesis undertaken by plants. Animals then ingest plants and use them to produce essential molecules
Photosythesis
Process by which plants trap sunlight in chlorophyll and use the energy to produce sugars and oxygen from water and carbon dioxide.
Chlorophyll A & B
Pigments in the leaves of plants that absorb light in the red and blue wavelengths which can then be used to synthesize carbohydrates
UV Exposure Dose Response Curve
Burden of disease increases if sun exposure is too high or too low. If too low, Vitamin D insufficiency and Skeletal Disease. If too high, skin cancer and eye disease.
Vitamin D
Essential nutrient for calcium uptake necessary for bone and tooth formation. Low levels of Vitamin d can lead to osteoporosis, rickets, and delayed tooth development in children.
Osteoporosis
Reduced bone calcium levels result in bones that are weaker and more prone to fracture.
Rickets
Soft bones and teeth in children caused by defective mineralization due to lack of calcium. Predominately a result of inadequate Vitamin D exposure.
Health Concerns of UV Exposure
Sunburn, Skin Cancer, Cataracts, Premature Skin Aging, Sun Allergy, and Actinic Keratosis
The Ozone Layer
The layer of the atmosphere comprised of Ozone, which is vital for absorbing UV light.
UV-A
Ultraviolet wavelength which travels through the ozone layer unimpeded
UV-B
Ultraviolet wavelength mostly blocked by the ozone layer except for the longer wavelength portion
UV-C
Ultraviolet wavelength most harmful, almost entirely absorbed by the Ozone layer in the atmosphere
Ozone
Continuously regenerating O3 molecules which absorb the energy of ultraviolet light when they are broken apart.
Chlorofluorocarbon (CFC)
Type of Haloalkane. They are harmful to the ozone layer because they introduce chlorine into the atmosphere which binds with O2 in the Ozone layer and prevent it from reforming O3.
Freon
A type of chlorofluorocarbon (CFC) that is odorless, colorless, nonflammable, noncorrosive, and safe to breathe. Invented in 1931 by Dupont Chemical to replace the previously used toxic refrigerants.
Ozone Hole
Depletion of Ozone over Antarctica and more recently, the Arctic. Result of the release of Chloroflurocarbons (CFCs) into the atmosphere.
How does UV light damage DNA?
Absorbed UV energy breaks molecular bonds of pyrimidines, which then erroneously reform, creating a pyrimidine dimer. This prevents that nucleotide from functioning as an information molecule and results in a base error when replicated or transcribed.
Basal Cell Carcinoma
Affects the lowest layer of cells, common but not very deadly
Squamous Cell Carinoma
Affects upper layers of skin cells, common but not very deadly
Melanoma
Rarest and most dangerous form
Melanocyte
Cells which produce Melanin
Melanin
Protects us from UV light by absorbing part of the UV spectrum so that it can’t damage DNA in the nucleus of the cell
SPF formula
SPF “Y” = 1/”Y”th of the sunburning energy allowed through.Minutes to burn = Normal burn time x “Y”
Nucleotide Excision Repair (NER)
Mechanism of repair which is to excise (remove) the damaged part of the DNA
Xeroderma Pigmentosum (XP)
Individuals who are not good at repairing damaged DNA due to an autosomal recessive genetic abnormality. Results in sensitivity to UV radiation leading to multiple skin disorders, skin malignancies, neuro and ocular abnormalities.
Polymorphisms
Changes in protein sequence that do not destroy protein function but alter is slightly. Can confer benefit or harm depending on the nature of the mutation.
Vienna Convention on the Protocol of the Ozone Layer
1985 - scientific concerns about the ozone layer prompt governments to adopt a legal framework for action on fixing the Ozone layer
Montreal Protocol on Substances that Deplete the Ozone Layer
1987 - international negotiators adopted legally binding commitments requiring industrialized countries to reduce/eliminate ozone harming chemicals
Spina Bifida
Congenital disorder of neural tube development where there is an opening in the spinal column of the developing fetus, affecting as many as 1 in 800 infants.Types:Occulta - Vertebrae are malformed leading to opening covered by a layer of skinMeningocele - spinal fluid and the meninges protrude through vertebral openingMyelomeningocele - spinal cord exposed through the opening, partial or complete paralysisMultifactorial - genetic, environmental, folic acid insufficiency
Nutritional Deficiency Disease
Vitamin B12 deficiency is common. Water soluble, so it needs to be ingested daily. Comes from meat, fish, brewer’s yeast, dairy. Some people have genetic predisposition to not store Vitamin B12
Vitamin B12
Controls levels of homocysteine which are associated with higher risk of heart disease. Converts homocysteine into methionine. Methionine then converted into S-adenosyl-methionine and tetrahydrofolate, which is critical for DNA sythesis.
Cardiovascular Disease Risk Factors
1) Tobacco Use2) Physical inactivity3) The harmful use of alcohol4) Unhealthy diets
CYP1A1
Defective enzyme in some people that make less reactive Benzo(a)pyrene (BaP) molecules (a molecule found in cigarettes which when metabolized readily reacts with DNA and can lead to mutations in the DNA and ultimately cancer). This could make people with this mutation less vulnerable to lung cancer.
Asthma
Respiratory disease associated with exposure to air pollution, dust, and plastics. Also associated with lack of exposure to parasites. Genetic component as well, several genes have been identified which confer risk.
Diabetes Type 2
People with type 2 diabetes make insulin but their bodies don’t respond well to it. Risk factors include: Family history, obesity, lack of exercise, poor diet, age, etc.
Cancer
Continuous uncontrolled growth of cells; characterized by their ability to metastasize, or grow outside of the tissue/organ they come from
Neoplasia
Abnormal proliferation of cells
Tumors
Abnormal mass of tissues which may be solid or fluid-filled. Tumors can arise from any cell type in the body. A tumor does not necessarily mean cancer. Tumors can be benign (not cancerous), pre-malignant (pre-cancerous), or malignant (cancerous)
Clonal
Arising from a single cell. Cancer arises from single cells, generally it takes decades for enough errors to accumulate in order for it to move from normal to pre-cancerous to actual cancer.
Carcinomas
90% of cancers, arise from epithelial cells
Sarcomas
Rare and consist of tumors of connective tissues (connective tissue, muscle, bone, etc.)
Leukemia
Referred to as liquid tumors. Arise from blood forming cells in the bone marrow.
Lymphomas
Called liquid tumors arise from the T and B cells of the immune system.
Rous Sarcoma Virus
First successful transmission of a tumor from one organism to another. Able to transfer tumors between chickens by injecting pieces of growth to chickens in the same bloodline (genetic component). But even when lysed and filtered, tumors still formed (infectious component). Rous had discovered a cancer-causing virus.
Retrovirus
Retrovirus uses RNA as genetic material. It gets translated into DNA and then integrated into the host genomic DNA. One RNA strand is used to make viral genetic material, the other is for the packaging of the newly formed viruses. Change to host cell DNA can result in cancer if the gene that is getting replaced is a growth regulating gene.
Sickle Cell Anemia
Caused by a single nulceotide change in the β-globin gene in a blood cell stem cell, this cell will then produce RBCs with that mutation. This mutation is hereditary, because it was in one or more of your parents germ cells, it is now in every one of your cells.
Proto-Oncogenes
Promote cell growth by coding for proteins that encourage growth and cell division. When mutated can lead to the loss of growth control, and become oncogenes (cancerous).
Tumor-Suppressor genes
Suppress cell growth by coding for proteins that slow or block growth.
Two basic types of genes involved in cancer
Oncogenes & Tumor-Suppressor Genes
Avoidable Causes of Cancer Death in the US
Schottenfeld et al 2013. Estimated that up to 60% of cancer deaths in the US can be attributed to avoidable risk factors such as:
- Tobacco Use
- Alcohol Abuse
- Ionizing and Solar Radiation
- Occupational exposures
- Infectious agents
- Obesity
- Physical Inactivity
Polycyclic Aromatic Hydrocarbons (PAHs)
Compounds that come from the burning of Carbon-based material. They are found in wood smoke, car exhaust, cigarette smoke, and charcoal-grilled foods, roasted, and smoked foods. Linked to increase risks of lung, skin, and urinary cancers.
Lines of Evidence for Environmental Causes of Cancer
1) Time Trends - lung cancer rates increase the longer people smoke
2) Geographic Variation - Differences in rates of specific cancers in particular geographical areas
3) Migration Studies - When on migrates to a new geographical area, they acquire cancers common to the new location
4) Occupational Cancers - Angiosarcoma of the liver, rare cancer found commonly in vinyl chloride workers
5) Animal Bioassays - exposure of animals to carcinogens can demonstrate that they cause cancer
<p>Alfatoxin</p>
<p>A toxin produced by the fungus Aspergillis 1. One of the most potent carcinogens known to man. Metabolized by CYP450 into a substance that induces a specific "signature" mutation that leads to hepatocellular carcinoma (HCC).</p>
Benzopyrene
Inert multi-ring structured molecule that is metabolized by the CYP450 system into a more reactive and mutagenic set of molecules. These can bind to Adenine or Guanine in DNA, leading to a mistake in DNA synthesis.
Ames Test
Test for mutagenic potential that mixes suspected carcinogen with liver extract in order to allow for the action of CYP450 on the compound. The compound is then placed with a bacteria mutated in a gene for the synthesis of tryptophan. If the compound is mutagenic it will cause a reversion of the mutation allowing the bacteria to produce tryptophan.
International Agency for Research on Cancer Carcinogenicity Scale
Group 1: Carcinogenic to humans
Group 2A: Probably carcinogenic to to humans
Group 2B: Possibly carcinogenic to humans
Group 3: Unclassified as to carcinogenicity in humans
Group 4: Probably not carcinogenic to humans
Breast Cancer Risk Factors
Strong Association:
- Age
- Mother or sister with breast cancer
- Previous breast cancer diagnosis
- Dysplastic hyperplasia
- Breast Density
Modest
- Early Age at Menarche
- Late Age at Menopause
- Age at first birth > 30 years
- Never had children
- Postmenopausal obesity
- 2+ drinks of alcohol a day
- High-dose radiation exposure
- Oral Contraceptive Use
- Hormone Replacement Therapy
- Little or no exercise
Tamoxifen
Estrogen receptor antagonist used to prevent Estrogen Receptor-Positive Breast Cancer
DNA Virus
Viruses with DNA genomes. When entering a cell they co-opt the cells machinery to synthesize virus DNA and proteins. The DNA enters the nucleus where its DNA is duplicated and RNA is made. A new viral DNA molecule is packaged into a new virus which then leaves the cell to infect other cells or spread to other individuals. Adenovirus is a an example.
RNA Viruses (+ ssRNA)
+single strand RNA (+ssRNA) viruses have genomes that are mRNA. If they are retroviruses, they bring a DNA synthesizing enzyme with them to convert their RNA into DNA. That DNA is then inserted into the genome, and at some later time viral RNA is transcribed from the inserted section to make new virus proteins and to be the genome of the virus.
Envelope Virus
A virus that surround itself with the host cell membrane, called an envelope. The envelope is used to recognize the best host cells.
Rhinovirus Life Cycle
A +ssRNA but NOT a retrovirus. Rather than being integrated into the host genome, it makes a -ssRNA, used as a template for the production of proteins that then replicate the genome of the virus and its necessary proteins.
Innate Immune Response
1) Fever - produced by factors released by cells including mast cells and macrophages, slows the rate of replication
2) Interferon - cytokines released by a cell infected with a virus
3) Natural Killer cells - cause lysis of any altered or infected cells that they encounter
Adaptive/Acquired Immune Response
B-cells - create antibodies which are specific to individual pathogens
T-Cells - recognize and kill infected cells
Ways that viruses can spread
- Carrier organisms (mosquitoes, fleas)
- Air
- Direct transfer of body fluids (saliva, sweat, nasal mucus, blood, semen, vaginal secretions)
- Surfaces (fomites) through body fluids left behind
Immune Response from Vaccine
Vaccines mimic natural infections, contain weakened or destroyed viruses
Macrophages engulf the virus and then present it as to the T and B cells for future identification
Herd Immunity
Public health concept that if large enough numbers of people are vaccinated, a measure of protection is given to the sensitive population by reducing the number of potential infected persons
Live Attenuated Vaccines
Weakened viruses grown in a different host. Like a natural infection, so it creates a strong immune response. Can’t be given to immunocompromised persons, they might not be strong enough to fight off the infection.
Inactivated Vaccines
Virus is either rendered non-infectious or killed when vaccine is made. Requires multiple doses to achieve and maintain immunity. Ex: Inactivated polio vaccine
Severe Acute Respiratory Syndrome (SARS)
Viral respiratory illness caused by a corona virus. Spread by close person-to-person contact, droplets, or fomites.
Influenza A
Viral particle with two major glycoproteins: Hemagglutinin and Neuraminidase. This is where the H and the N in influenza names comes from.
Antigenic Drift
Strains defined by tiny differences between subtypes, different versions of same H genes
Antigenic Shift
Different strains of viruses combine to make a new virus.
Tamiflu
Antiviral medication, works by preventing budding virions from departing their host cell.
Acquired Immune Deficiency Syndrome (AIDS)
Disease condition of compromised immunity caused by the effect of Human Immunodeficiency Virus (HIV) on the cells of the immune system. Diagnosed when certain infections begin to occur or immune response is otherwise measured as severely depressed.
Ebola Virus
Ebola virus is a member of the Filoviridae family of viruses that contains a single, linear, negative-sense ssRNA genome
Ebola Virus Species
1) Ebola virus (Zaire ebolavirus) causing current outbreak
2) Sudan virus (Sudan ebolavirus) associated with large outbreaks in Africa in the past
3) Bundibugyo virus (Bundibugyo ebolavirus) associated with large outbreaks in Africa in the past
4) Taï Forest virus (Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus);
5) Reston
Ebola Virulence
Majority of patients unable to develop sufficient immune responses. Ebola targets endothelial cells, mononuclear phargocytes, and hepatocytes. It also blocks interferon (INF) from acting normally.
Cytokine Storm
White blood cells release large amounts of proinflammatory cytokines that increase the permeability of the vascular endothelium. This is counter-productive because it facilitates easier access to secondary viral targets, and calls macrophages to the site of infection that a virus can use to spread.
