The use of monoclonal antibodies in enabling the targeting of specific substances and cells. • evaluate methodology, evidence and data relating to the use of vaccines and monoclonal antibodies • discuss ethical issues associated with the use of vaccines and monoclonal antibodies.

So... what are monoclonal antibodies?
Monoclonal just means a group of the same thing, so when we talk about monoclonal antibodies we mean a whole load of antibodies that are exactly the same. This is significant because inside the body, you find many different types of antibodies: this is because B cells which produce antibodies are induced to clone by antigens on the surface of a pathogen, there are many different antigens on a single cell, so many different B cells are produced and hence many different antibodies (polyclonal).

How are they made?
There now several ways to produce monoclonal antibodies, the one below is Milstein and Kohlers method (1975):

1. Introduce a pathogen (with complimentary antigens to the antibody you want) to a mammal.
2. The antigen will induce the cloning of the B cell that produces the right antigen. However, it will also produce others, giving B cells that will produce polyclonal antibodies.
3. The B cells are taken out of the body and fused with tumour cells. The result is a hydribomas which is a cells that produces antibodies but can live for a longer time and divide outside the body.
4. Different hybridoma are separated off and left to divide until it forms a group (a clone).
5. Each clone is screened for the antibody that is needed- if it is being produced then it is grown on an industrial scale.
6. Antibodies are extracted from the clone.

What are they used for?

Monoclonal antibodies are useful in the treatment of illness and the application of science because they allow the targeting of specific cells due to the fact that they will only bind with one antigen.

• Separation techniques.
• Immunoassay: when you take a pregnancy, drugs or HIV test, there are complimentary monoclonal antibodies in the test which will form an antigen-antibody complex with the protein that is being looked for which triggers a colour change.
• Cancer therapies: trigger the immune system to attack cancer cells; carry radiation to the cancer cells; block signals that tell the cancer cells to divide.
• Preventing rejection of transplanted organs: by targeting the T cells involved with destroying the foreign tissue.
• Diabetes treatment.

What are the associated ethical issues?

• You have to give cancer and illness to mammals (mice).
• You have to make transgenic mammals (giving the properties of humans to make the antibodies suitable to use in the treatment of people).
• Testing on humans caused organ failure.
• Some people with MS have died as a cause.

The use of vaccines to provide protection for individuals and populations against disease. • evaluate methodology, evidence and data relating to the use of vaccines and monoclonal antibodies • discuss ethical issues associated with the use of vaccines and monoclonal antibodies • explain the role of the scientific community in validating new knowledge about vaccines and monoclonal antibodies, thus ensuring integrity • discuss the ways in which society uses scientific knowledge relating to vaccines and monoclonal antibodies to inform decision-making.

Vaccines involve injecting a weak or inactive form of a pathogen into the body.

The antigens stimulate an immune response from white blood cells.

The cells destroy the pathogen, but more importantly, they also produce memory cells.

This means that if the real pathogen enters the body, memory cells will produce large amounts of plasma cells very quickly to combat the pathogen- so it is destroyed before it can harm the body.

This is often carried out throughout whole populations so that everyone is protected against a pathogen and it can be eradicated.

Using a weak or inactive form of the pathogen means that there is no risk of the pathogen from the vaccine harming the body.

The MMR vaccine
A vaccine that protects against Measles, Mumps and Rubella is given to all children in the UK to prevent them getting these potentially disabling diseases. Andrew Wakefield published a study on the vaccine in 1998 which appeared to show that it increased the risk of children getting autism.

The claims are now believed to be completely unfounded in light of: new research showing no link; the small sample size he used; his vested interest to prove the link for the Legal Aid Board. However, at the time there was a big following of this idea and many people decided not to vaccinate their children. As a result the cases of all three diseases rose.

Ethical issues

• Testing on animals
• Potentially harmful testing on humans
• Possible side effects
• The fact that it might breach peoples rights to make vaccines compulsory

The effects of antigenic variability in the influenza virus and other pathogens on immunity.

Some pathogens have many different strains.

Influenza (common flue) is an example of a pathogen with multiple strains.

The different strains have different antigens- this is known as antigenic variability.

Memory cells will recognise antigens they have seen before and tackle a pathogen before symptoms arise- this is why you can only get chicken pox once.

However, if the antigen is different, the memory cell will not recognise it and be able to destory it.

This means that it is down to the slower and less effective primary response to kill the pathogen, allowing time for the pathogen to harm the body and cause symptoms- this is why you can get influenza multiple times.

The essential difference between humoral and cellular responses as shown by B cells and T cells. The role of plasma cells and memory cells in producing a secondary response.

Lymphocytes are white blood cells. They are created as stem cells in the bone marrow. They have defences that are specific to the pathogen they are attacking (unlike phagocytes which do the same for everything) which makes response slower, but more effective long term.

B cells

• mature in the bone marrow
• respond to antigens in the bodies fluids: tissue fluid; blood (humoral response)
• produce antibodies
• produce memory cells

1. ingest pathogen and present antigens on the surface
2. these are recognised by helper T cells, which stimulate mitosis
3. plasma cells and a Memory cells are produced
4. plasma cells secrete antibodies which attach to antigens on a pathogen to destroy it (primary response)
5. memory cells stay in the blood stream for many years, if they encounter the same pathogen again, they can divide rapidly and with greater intensity to make plasma cells which will make antibodies (secondary response)

The secondary response provides long term protection as they memory cells stay alive for many years. They produce many more plasma cells and are much faster at doing so than the primary response, this means that the pathogen can be fought before it causes harm to the body.

T cells

• mature in the thymus glands
• recognise antigens if presented on the surface of other cells (cell-mediated response)
• stimulate b cells and phagocytes
• kill infected cells
• produce memory cells

1. Phagocytes, infected cells and cancer cells all display antigens on their surface
2. A specific helper T cell will have receptors that fit exactly with the antigens- when they meet, the helper T cell stimulates other T cells to form appropriate clones by mitosis
3. These T cells can: stimulate B cells; stimulate phagocytes; develop into memory cells; kill cells
4. They kill cells by producing a protein which breaks cell-surface membranes.

Antibody structure and the formation of an antigen-antibody complex.

Antibodies are often compared to a Y shape because of their one receptor binding site and two pathogen binding sites.

Antibodies are made of two different polypeptide chains, a light chain and a heavy chain. They are attached to each other, but can move in the pathogen binding site to help bind to the pathogen.

The variable region is different on different types of antibody because it needs to be specific to the antigen it is targeting. The constant region is the same in all antibodies.

The variable region has a tertiary structure that is complimentary to (fits with) that of the antigen it is aiming to destroy- this is so that the two can bind and form what is known as an antigen-antibody complex.

wikipedia

Definition of antigen and antibody.

An antigen is a 'marker' on a cell that is foreign to the body that identifies it as non-self.

An antibody is a protein produced by the body to destroy pathogens.

Phagocytosis and the role of lysosomes and lysosomal enzymes in the subsequent destruction of ingested pathogens.

Phagocytes are white blood cells. They destroy bacteria by engulfing them and breaking them down- this process is called phagocytosis.

The phagocyte recognises a pathogen because of its chemical products and so moves towards it.

It then binds with the pathogen and begins to engulf (wrap around) it- by doing this it forms a vesicle (sac) with the phagocyte inside it know as a phagosome.

Lysosomes (vesicles with enzymes inside) release digestive enzymes into the phagosome, this means that it can be broken down. Useful products are absorbed by the cell and others are excreted.

Risk factors associated with coronary heart disease: diet, blood cholesterol, cigarette smoking and high blood pressure. Candidates should be able to describe and explain data relating to the relationship between specific risk factors and the incidence of coronary heart disease

A number of factors can increase the risk of coronary heart disease:

Diet

• Salt raises blood pressure.
• Saturated fat increases blood cholesterol.

Blood cholesterol

• Low-density lipoproteins associate with white blood cells to cause atheromas.
• High-density lipoproteins help lower cholesterol.

Smoking

• Nicotine stimulates the production of adrenalin, this causes a quicker heart rate and therefore raises the blood pressure.
• Nicotine makes platelets stick together, so thrombosis is more likely.
• Carbon monoxide combines with heamaglobin so less oxygen can be carried in the blood. The heart has to pump more quickly to deliver the same amount of oxygen, so blood pressure is raised. The heart muscles may not get enough oxygen leading to a heart attack or angina (chest pain).

High blood pressure

• Arteries are put under more pressure so will form hard walls to resist the pressure- these thicker walls constrict blood flow.
• The pressure can burst open the arteries (haemorrhage).

Cardiac output as the product of heart rate and stroke volume.

Cardiac output is a measurement of how much blood is being pumped by the heart, it is calculated by multiplying the speed at which it is pumping by how much it pumps each stroke.

Cardiac output= heart rate x stroke volume.

Myogenic stimulation of the heart and transmission of a subsequent wave of electrical activity. Roles of the sinoatrial node (SAN), atrioventricular node (AVN) and bundle of His.

Myogenic stimulation means that the heart is caused to move because of signals that originate inside of it. In normal muscles movement is caused by signals from the CNS.

The signals come from the sinoartrial node (SNA) which is sometimes refered to as the pace maker. Although the signals for the cardiac cycle are generated in the heart, the pace is controlled by signals from the brain.

• SNA sends electrical activity accross the top of the atria (they contract)
• The atrioventricular septum is non-conductive tissue which stops the signal going down the sides.
• The signal that travelled down between the atria reaches the atrioventricular node (AVN).
• The AVN delays the signal (so that the atria fully contract) before transmitting it again.
• The electrical activity now travels down the bundle of His.
• The signal reaches the bottom of the ventricles where it causes them to contract.

Its important that the ventricles contract upwards so that the blood is being pushed towards the semi-lunar valves.

It is also of importance that the AVN delays the signal long enough for the atria to finish their contraction- so that the most blood possible goes into the ventricle before it starts contracting and closes the atrio-ventricluar valves.

Pressure and volume changes and associated valve movements during the cardiac cycle. Candidates should be able to analyse and interpret data relating to pressure and volume changes during the cardiac cycle.

Diastole

The ventricle relaxes, decreasing its pressure. This causes the blood which it just pushed into the aorta/pulmonary (left/right) flow back towards the heart trying to get to the low pressure area: the blood pushes the semi-lunar valve shut (making the second noise of a heart beat 'dub')

Blood flows from the atrium into the ventrical. This happens because there is a lower pressure in it: 1. because it has no blood in and 2. because it has just relaxed.
The blood going through pushes the atrio-ventricular valves open.

Atrial systole

The atrium contracts: so there is more pressure on the blood. It does this to push the remaining blood into the ventricle that didn't flow in during diastole.

Ventricular systole

Ventricles contract- more pressure- pushing blood through the semi-lunar valves, out of the heart.
When they contract the blood pushes against the atrio-ventricular valve, which pushes it shut (this makes the first sound of a heart beat 'lub')

http://library.med.utah.edu/kw/pharm/hyper_heart1.html

Atrium (left):
Bump- atrium contracts.
Drop- blood is pushed into ventricle.
Gradual rise- blood fills the atrium.
Drop- blood flows into ventricle.
Gradual rise- blood continues to flow in and through into the ventricle.

Ventricle (left) pressure:
First small bump- blood is pushed in by atrium.
Massive bump- the ventricle contracts.
Fall with aorta line- blood has been pushed out.
Fall after the aorta line- ventricle relaxes.
Gradual rise- pressure is below that in the atrium so blood rushes in.

When the ventricle pressure rises above that in the atrium, the atrio-ventricular valve is pushed shut.
When the ventricle pressure falls below that of the atrium, the atrio-ventricular valve opens.

Ventricle (left) volume:
Initial rise- blood is pushed in from the atrium.
Fall- blood is pushed out into the aorta.
Plateau- both valves are closed so no blood is moving in or out (volume can't change.)
Increase- blood flows in from the atrium.


Aorta:
When the pressure of the ventricle meets that of the aorta the semi-lunar valve opens.
Big bump- blood is pushed in from the ventricle.
The ventricle pressure drops below that of the atrium, back flow shuts the semi-lunar valve.
Small bump- the elasticity of the walls brings them in before...
Gradual fall- the walls of the aorta relax.

Valves are pushed open because the pressure has been made grater in one chamber than it is on the other side of the valve, so blood tries to go through it into a lower pressure area, pushing it open.

The gross structure of the human heart and its associated blood vessels in relation to function.

The heart has four main areas: two atriums and two ventricles.

• Blood first enters the heart into the right atrium from the vena cava;
• passes through the right atrio-ventricular valve into the right ventricle;
• leaves through a semi-lunar valve into the pulmonary artery;
• goes past the lungs in capillaries where it is oxygenated;
• then re-enters the heart through the pulmonary vein into the left atrium;
• passes through the left atrio-ventricular valve into the left ventricle;
• then out through the left semi-lunar valve into the aorta (which takes it to the body.)

wikibooks

Veins always going into the heart and arteries away from it.
Atrium means entrance hall in latin.
Pulmonary means to do with the lungs.

The mechanism of breathing.

When volume is increased pressure is decreased.
Air rushes into areas of lower pressure.
So increasing volume in the lungs brings air in:

Breathing in (inspiration)
Diaphragm contracts: flattens- increasing volume.
Intercostal  muscles contract: pulling up and out- increasing volume.

When volume is decreased it increases pressure.
Air rushes to areas of lower pressure.
So if volume is decreased in the lungs air will rush out:

Breathing out (Expiration)
Diaphragm relaxes: becoming a dome shape and pushing up- decreasing volume.
Intercostal muscles relax: pushing the ribcage down and in- decreasing volume.

Pulmonary ventilation as the product of tidal volume and ventilation rate.

Tidal volume is the amount of air breathed in. Measured in decemeters cubed.

Ventilation rate is the number of breaths taken in one minute. Measured in minutes to the power of -1.

If you times these two things together you get a measure of pulmonary ventilation in dm3min-1.

The exchange of gases in the lungs.

Oxygen diffuses from the alveoli- where it is in high concentration- into the capillaries- where it is in low concentration.

Carbon dioxide diffuses from the capillaries- high conc.- into the alveoli- low conc..

The essential features of the alveolar epithelium as a surface over which gas exchange takes place.

Epithelila cells make up the walls of alveoli.

The alveoli are surrounded by capillaries, this means there is a constant flow of blood that takes oxygen away from the area of diffusion, and the lungs bring a constant supply of oxygen to be diffused on the other side; the opposite is true for CO2- this keeps a big difference in concentration gradient to speed up diffusion.

Both alveoli and capillaries have very thin walls making the diffusion distance short (so diffusion happens more quickly.)

Because there are so many alveoli there is a very large total surface area fro gasses to diffuse through (quicker diffusion.)

There is mucus lining the alveoli which helps gasses to diffuse across.

The gross structure of the human gas exchange system limited to the alveoli, bronchioles, bronchi, trachea and lungs.

Once air is breathed in through the mouth or nose it travels down the trachea. The trachea splits into two- one going into the left lung and one going into the right lung- these pipes are called bronchi. Each bronchus will then divide further into many bronchioles: each ending in a sac called an alveoli.

The trachea and bronchi have walls of muscle that are supported by cartilage. The cartilage is in partial rings so that the tubes can be moved in any direction. Cilia on the walls move mucus out of the breathing system and into the stomach.

wikibooks

The use of oral rehydration solutions (ORS) in the treatment of diarrhoeal diseases. The applications and implications of science in developing improved oral rehydration solutions; ethical issues associated with trialling improved oral rehydration solutions on humans.

Diarrhoea leaves people dehydrated and with depleted amounts of necessary salts, as these things are lost in faeces. Cholera is an example of an illness that causes diarrhoea.

Oral rehydration solutions (ORS) are used to rehydrate and replenish key molecules.

ORS is a mixture of water, salts and sugars. A simplified ration is 1 litre of water to six teaspoons of sugar to half a teaspoon of salt. The water is often boiled to sterilise it.

• Sodium is needed because it goes into the cells and brings the water potential back down, this means water will move by osmosis back into the cells, and from there into the blood.
• Sodium has to enter the cells through co-transportation (because the normal carrier proteins are pumping sodium out) with glucose- this means that glucose is also needed.
• Other salts that make ORS isotonic; so that when people are drinking it their cells do not absorb all of the water and burst.

To work out the right proportions of salts and liquids, a lot of testing had to be done. This involved trialling early mixtures on humans to note the side effects and make appropriate changes. In the process many peoples conditions were worsened due to having too much of a certain molecule: too much glucose in one trial resulted in more water being drawn into the intestine and the diarrhoea was worsened.

Some claim that it is immoral to jeopardise peoples health by giving them un-trialled solutions; however, by trying out the solutions on people, scientists were able to refine ORS to create an effective treatment that saves many lives.

The specification wants you to say it contains glucose and:
Sodium (ions) / potassium (ions) / chloride (ions) / citrate (ions); 

Cholera bacteria produce toxins which increase secretion of chloride ions into the lumen of the intestine. This results in severe diarrhoea.

Toxins produced by the cholera bacteria effect the epithelial cells of the intestine- this is because it is complimentary to the receptors that only these cells have.

One half of the toxin binds to a receptor on the surface of the cell- this gives the other half access to the cell, so it can affect the producer of cAMP (that being a signal used within the cell).  The signal causes a protein channel to transport chloride ions out of the cell.

The effected cells are in the intestine, which chloride ions will now begin to flood into. The chloride ions lower the water potential in the intestine so water moves into it (along the gradient from high to low.) The intestines are where faeces is made, so when an effected person defecates it has a very high water content- diarrhoea. Because there is a lot of water in the intestine, molecules like salts will move into the intestine too (where they are in lower concentration) meaning that they too are lost in faeces.

The cholera bacterium as an example of a prokaryotic organism. The structure of prokaryotic cells to include cell wall cell-surface membrane, capsule, circular DNA, flagella and plasmid.

The bacterium that causes cholera is a prokaryotic organism as are all bacteria. 

These cells contain fewer organelles than an animal cell, and have some other features.

They have a cell-surface membrane, but they also have a cell wall like a plant: they have another layer outside of this to offer additional protection called a capsual.

The DNA in these cells is not contained within a nucleus- it is just a scrunched up ring called circular DNA.

A flagella helps bacteria move- often associated with sperm cells, but they are also important for cholera bacteria to get through the mucus lining to the epithelial cells in the small intestine.

Plasmids are small sections of DNA that are separate from the main circular DNA and replicate separately from it. They can carry genes that the bacteria didn’t always have and can be transferred between bacterium.