Health 101 Midterm1 Revision Notes - Health Inequalities, Immune System and Infection.

1. Strength of association
2. Graded response to graded dose
3. Consistency
4. Temporal relationship
5. Plausible mechanism

• Cofounding:  

• Observational studies-non-randomized observation of what happens to ppl under exposure to ppl outside the control of researcher

Two types of observational studies:

• Descriptive: does not test hypothesis, describes how things are{surveys-health habits}
• Analytical: hypothesis looks at outcome variable{relations between two problems}

• Case Study - A study of one diseased individual, providing a detailed description, of an uncommon disease; provides timely or rare information.
• Case Series - A study of multiple occurrences of unusual cases that have similar characteristics.  frequency of symptoms or characteristics of people with the disease. 

• Results may generate causal hypotheses  → but do NOT test a hypothesis

• Cross-sectional study: Survey in which the purpose of the analysis is to record associations between variables
• Case Control Study(retrospective)(simple)-analyzes subjects with a case group(smokers)

• advantage of this is good for studying rare disease less time can look at multiple risk factors
• disadvantage of this less quality of data, difficult to find ppl

• Cohort study(prospective)(more complex)-selection of population(smoking habits)follows for years

• Advantage of this keep tracks of exposures all along, lots of diseases can be studies, easier
• Disadvantage-have to follow people over long period of time expensive compared to case control

• Control Group-analyzes case group with similar ages sex etc.

• Ecological Studies-measures population not individual,provides powerful clues when comparing large populations,uses government data, cant prove the cause and effect

• Interventions test the effects of treatments: Medical/Surgical procedure, New drug, Lifestyle change intervention.Dietary change,Researcher has control over intervention,Timing, dose, intensity

Randomized Control Trials

• Assign them randomly to either the experimental group or "control" group

• which may receive no treatment, the conventional treatment, or a placebo(sugar pill)

Meta Analysis

• several separate but similar experiments or studies in order to test the pooled data for statistical significance

LEC 7

• Mortality & morbidity: used by international agencies to compare health status btw countries

-Mortality # of deaths in a population

-Morbidity refers to the disease state in individual

Individual measures and population-level indicators

1. Aggregate measures: combined data from individual people summarized at regional or national levels.  E.g. prevalence of obesity

2. Environmental Indicators:

• factors external to individual, such as air/water quality
• Can also be social characteristics
• May have analogues at the individual level

3. Global:

• No analogues at the individual level
• E.g. healthy public policy, social equity in access to health care, etc.

• Incidence – Measure of speed at which new cases of diseases (or deaths) arise in a population during a fixed time.
• Prevelance- total number of cases of a disease in a given population at a specific time

• Potential years of life lost (PYLL)
• Combination of morbidity and mortality outcomes

• Quality-Adjusted Life Years (QALYs)
• Disability-Adjusted Life Years (DALYs)
• Health-Adjusted Life Expectancy (HALE)

LEC 8

• Information in DNA stored as a code made of 4 chemical bases:

• Adenine (A) pairs with T
• Guanine (G) pairs with C
• Cytosine (C)
• Thymine (T)

• Splice-rna molecule through transcription
• genome is the complete set of genetic material in an organism(dependent on environment)
• Alleles are forms of the same gene with small differences in their DNA sequence
• Chromosomes & chromatin are made of DNA coiled around   proteins called histones
• Karyotype-chromosomes lined up in pairs

Types of Proteins

• Enzymes: Carry out almost all of the 1000s of chemical reactions in the cell
• Messengers: Transmit signals to regulate processes (hormones)
• Antibodies: Bind to foreign particles as part of immune response
• Structural components: Provide structural support for cells and tissues, allow for movements
• Transporters: Proteins that bind to molecules to allow transport across membranes

• Immunoglobulin G- is a type of antibody that circulates in the blood and recognizes foreign particles that might be harmful.
• Study transcription and translation in textbook

LEC 9

• Transcription Factors-activation of protein through environment, increases or decreases transcription binds to regulatory regions
• Apoptosis-damaged cell undergoes apoptosis(kills itself) if it is unable to repair genetic errors
• Metastasis- spreading occurs of cells that break away from tissue produce cancer cells)

• Occurrence of mutations

• Inherited: Present in germ or egg cells
• Acquired: DNA of individual somatic cells during lifetime (e.g. mutations that lead to cancer)
• Polymorphisms: normal variations in DNA(affects our susceptibility to diseases)

• Exogenous factors: environmental factors, such as smoking, sunlight, radiation (X-rays), or chemical agents  → All called mutagens
• Endogenous factors: errors during DNA replications, toxic by-products of cellular metabolism (i.e. free radicals-toxic substances in DNA)

Mendelian-single gene disorders

1. Molecular genetic diseases-sickle cell,cystic fibrosis
2. Metabolic genetic disorder-alteration of protein in enzyme—PKU,galactosemia
3. Nucleotide repeat disorders-Huntington disease

• PKU-phenylketonuria leads to mental retardation by killing neurons in brain

• Breast Cancer-Mutations in BRCA1(chromosome 17) or BRCA2(chromosome 12) gene

LEC 10

Pathogen-source of infection                means of transmission-hand washing

Resevoir-treatment                                 portal of enetry-condoms

Portal of exit-condoms,masks               new host-immunization

←this chain can be broken from public health measures by being clean(don’t do this stuff)

Leukocytes-white blood cells produced in born marrow

• Neutrophils-ingests pathogens to the areas of invasion
• Marcophages-big eaters they are scavengers eating pathogens and worn out cells
• Dentritic cells-stay in tissue and eat pathogens and active immune cells
• Natural killer cells-destroy infected and cancerous cells

IMMUNIOLOGICAL DEFENDERS:

Lymphocytes:T cells and B cells

T cells:helper,killer,suppressor t cell

B cell-lymphocytes produce antibodies some T and B have memory cells

• Antibodies produced by B cells have complementary surface markers that bind to specific antigens

Innate/Natural response

• Inflammatory response

• Mast cells release histamine
• Dilation of blood vessels
• Heat, swelling, and redness

Phase 1

• Dendritic cells arrive, consume foreign cells, and relay information to helper T cells, which rush to respond

Phase 2

• Helper T cells (CD4+) multiply rapidly and trigger production of killer T cells and B cells in the spleen and lymph nodes.
• Cytokines such as interleukins and interferons stimulate production of T cells, B cells, and antibodies.

Phase 3

• cell-mediated immune response: Killer T cells (CD8+ cytotoxic T cells) destroy foreign cells and cells of the body that have been invaded and infected.
• antibody-mediated immune response: B cells produce antibody molecules that bind to antigen-bearing targets, thereby marking them for macrophages to consume

• Abs only work again pathogens in body NOT inside cells.

Phase 4

• Suppressor T cells stop the immune response and restore balance.
• Dead cells are filtered and excreted.

• Lymphocytes are reserved as memory T cells and B cells.

Symptoms and Contagion:

• Incubation:

• Pathogens actively multiplying inside the body’s cell
• Usually without symptoms of illness
• May be contagious

• Prodromal period:

• After incubation
• Initial symptoms begin to appear
• Highly contagious period
• In cases of acquired immunity → infection may be eradicated

• Symptoms

•  Many due to immune response rather than actions/responses of pathogen
• Fever causes by release of cytokines

• Cytokines travel to the brain and reset the body’s thermostat to a higher level to improve immune responses

• Cold symptoms caused by the destruction of body cells by lymphocytes

• Runny nose caused by lymphocyte destruction of mucosal cells

• Flu symptoms are caused by pro-inflammatory cytokine

• Immunotherapy-expose ppl to small amounts of the  allergan e.g. the peanut experiement
• Most allergic reactions are due to the production of a special type of antibody known as immunoglobulin (IgE)(<- that’s why ppl have allergies)
• Anaphylaxis -Severe systemic hypersensitive reaction characterized by difficulty breathing, low blood pressure, heart arrhythmia, seizure, and sometimes death.

Lec 11

Pneumonia-most prevalent infection each year

Infectious diseases cause 19% of all deaths every year

• Classified according to shape:
• Bacilli (rod shaped)
• Cocci (spherical)
• Spirochete (spiral shaped)
• Vibrios (comma shaped)

• Reproduce rapidly (binary fission), Single-celled prokaryotic organisms(no nucleus)(bacteria)
• Microbes occupy body surfaces skin gut mucous
• Gut-prevention of colonization of disease causing bacteria(10 trillion bacteria), vitamin synthesis, break down food, stimulates immune system

• Genetic mutations can lead to new phenotypes that make organisms better adapted to survive in specific environments
• Bacteria reproduce every 20 mins

• Pathogensis:due to bacteria;ie botulism from bolutinum toxin canned food

1. Either human  host during infection,food or water consumed by human

• Direct damage to tissue or cells of host by bacteria itself or inflammatory reponse of immune system
• Genetic mutations can lead to new phenotypes that make organisms better adapted to survive in specific environments

• Pneumonia:

 Inflammation of the lungs, caused by:

• infection with bacteria, viruses, or fungi, or
•  by contact with chemical toxins or irritants.
• Ranked 7th (along with influenza) leading cause of death in Canada

• Children < 2, adults > 75, and those with other chronic health problems most vulnerable

• Most common cause of bacterial pneumonia is pneumococcus bacteria

Vaccine available

Meningitis:

• Infection of the meninges: membranes covering the brain and spinal cord
• Viral meningitis mild and goes away on its own
• Bacterial meningitis can be life threatening and requires immediate treatment with antibiotics.

• In Canada, fatal in 10% of all cases 
• Children routinely receive vaccination against Haemophilus Influenzae type b (Hib)
•  Worldwide 170,000 people die each year (mostly sub-Saharan Africa)

Staphylococcal Infections:

• Spherical, clustered bacteria commonly found on the skin or in the nasal passages

• 30% of people carry it on their bodies

• May enter body and cause

• Minor skin infections - boils
• Pneumonia(in lungs)
• Toxic shock Syndrome

• MRSA: methicillin-resistant Staphylococcus aureus  → 

• Superbug
• Nosocomial infection - Major emerging threat in hospitals

Tuberculosis

• Chronic bacterial infection that affects the lungs
•  Spread via respiratory route
• Only 10% of latent TB infections become active

• In Canada, highest among aboriginal and foreign-born immigrants

• 1/3 of worldwide population infected
• Emergence of strains with resistance to second-line antibiotics

• MDR TB: Multi-drug resistant
• XDR TB: Extensively drug resistant

Viruses

• Lack all enzymes essential to energy production and protein synthesis in normal animal cells
• Composed of nucleic acid (DNA or RNA), proteins, and surrounded by glyco-protein coat
• Cannot grow or reproduce themselves
• Take what they need for growth and reproduction from the cells they invade (parasites)
• Cause illnesses known as contagious diseases

Examples of viruses:

• The common cold

• May be caused any of more than 200 different viruses (rhinoviruses and coronaviruses)

• Influenza

• The flu, an infection of the respiratory tract

• Measles, mumps, rubella

• Childhood illnesses that have waned in Canada due to vaccines

• Chicken pox, cold sores, herpesvirus infections

• Once infected, you are never free of the virus

Antigens of flu virus coats:

• Structure of flu virus

• Lipid bilayer derived from plasma membrane of host cell
• Integral membrane proteins in bilayer

• hemagglutinin ("H”) (1-15)
• neuraminidase ("N”) (1-9)
• Serve at antigens to immune system
• M2 protein

• Inside shell are 8 RNA molecules and matrix proteins

Antigen change

• Antigenic drift

• Mutation in RNA within the virus that cause small changes in the hemagglutinin and neuraminidase antigens on the surface of the virus

• Antigenic shift

• Reassortment, or genetic recombination between different strains or host species

• Completely new antigens
• New host!

• Viral encephalitis

• Inflammation of brain tissue

• Viral hepatitis

• Inflammation of the liver

• Poliomyelitis

• Affects the nervous system causing irreversible paralysis and death

• Rabies

• Infection of the central nervous system

• Human papillomavirus

• A variety of types HPV cause warts
• Some types cause cervical cancer → Vaccine

Hepatitis

• Several forms that cause inflammation of the liver

• Hepatitis A virus (HAV)

• mildest form
• transmitted by an infected person or food or water contaminated by sewage.

• Hepatitis B virus (HBV)         

• transmitted sexually

• Hepatitis C virus (HCV)

• direct contact with infected blood via injection, drug use

• 85% become chronic carriers
• Can develop chronic liver disease, cirrhosis, or liver cancer.
• Most common reason for liver transplants

• AZT is a reverse transcriptase inhibitor used in HIV treatment
• There are antiviral drugs but they cannot provide a cure meaning cannot get rid of the virus inside of use

Malaria

• Caused by a a protozoan of

  the genus Plasmodium 

• Recurrent attack of severe

   flu-like symptoms

• Injected into bloodstream

   of host by mosquitos

• Most prevalent infectious

   disease worldwide

• 350 – 500 million new cases each year!
• > 1 million deaths each year → children < 5

Prions

• Fatal degenerative disorders of the central nervous system have been linked to prions
• Lack DNA or RNA and consist only of protein

• Their presence in the body does not trigger an immune response
• They have an abnormal shape and form deposits in the brain
• May trigger normal proteins to change their structure to the abnormal, damaging form

• Transmissible spongiform encephalopathies

• Sponge-like holes in the brain
• Creutzfeldt-Jakob disease, bovine spongiform encephalopathy