Health and disease III

Drug development

Possible drugs are synthesised (made) in a lab

In Vitro Screening - potential medicines are tested on cell cultures, tissue cultures and isolated organs.

Animal testing - Chemical are then tested on animals, to find out how they work in a living organism as well as what dose is needed and any side effects

Clinical testing - Healthy volunteers are given a very low dose, which is gradually increased. If the results are good, it can be tested on people suffering from the illness. The optimum dose is found.

Placebos - Some patients are given a placebo, a substance that looks like the drug, but doesn't do anything, e.g. a sugar pill. It allows the doctors to see the actual difference the drug makes

Blind and double blind trials - The patient doesn't know whether they are getting the placebo or the drug. Double blind are when the doctor doesn't know either

Once the drug has passed all the test, it will be granted a licence and can be prescribed to patients

Antibiotics

Either kill bacteria (bactericidal) or prevent them from reproducing (bacteriostatic)

No effect on viruses

No effect on human cells

Some bacteria develop resistance due to mutations or over-prescribing

Bacteria never become immune to an antibiotic

Investigating antibiotics and Antiseptics

In a lab

Cultured in a growth medium containing : carbohydrates, minerals, proteins and vitamins

Growth medium can either be agar jelly or a nutrient broth solution

Incubate the bacteria at 25 degrees to prevent the growth of harmful pathogens

Make sure enough oxygen is available to prevent the growth of anaerobic bacteria

The effect of substances of bacteria growth

Place paper discs soaked in different types antibiotics on a sterilised agar plate with an even covering of bacteria. Makes sure to leave space between the disk

Antibiotics should diffuse into the agar jelly.

Antibiotic resistant bacteria will continue to grow on the area around the paper disks

A clear area will be left where the bacteria have died as they are non-resistance to the antibiotic

Make sure to use a control, a paper disk with no antibiotic so you can be sure the paper has no effect

Leave the petri dish for 48 hours at 25 degrees

Calculate the area of the inhibition zone

The more effective the antibiotic, the larger the inhibition zone

Preparing an uncontaminated culture

Petri dishes and growth mediums must be sterilised before use. This can be done by placing them in an autoclave which uses high temperatures to kill any pathogens

If an inoculating loop is used, it must be sterilised by passing it through a flame and then cooled

Working next to a Bunsen burner will kill airborne microbes due to convection currents

The lid of the petri dish should be lightly taped on to allow oxygen to enter the dish to prevent the growth of anaerobic bacteria

The dish should be stores upside down to prevent drops of condensation falling on the agar

Risk factors for non-communicable diseases

What are risk factors?

Things linked to an increases in the likelihood that a person will develop a disease

Some risk factors are unavoidable like age or gender

Some risk factors are lifestyle based ad can be changed

Many diseases are cause by several risk factors

The more risk factors you have for one disease the more likely you are to get it

Smoking

Major risk factor for Cardiovascular disease, associated with the heart and blood vessels

Nicotine increases heart rate, which increases blood pressure

High blood pressure can damage artery walls which can lead to the build up of fatty deposits

This can cause a heart attack or stroke

Smoking is also a risk factor for cancer, cigarette smoke contains chemicals called carcinogens which can cause mutations in the genes that control cell division

Alcohol

Drinking too much alcohol is a major risk factor for liver disease

Ethanol is broken down in the liver and the toxic products can damage live cells

Toxic chemicals from the intestines can also cause liver damage

Drinking too much over a long period of time can lead to permanent liver damage

Diet

Diets with too few nutrients can lead to malnutrition, and is a risk factor for scurvy

Too many nutrients can lead to obesity, which is a risk factor for diabetes and CVD

Exercise

Too little exercise can lead to obesity

Inactive people are more likely to develop high blood pressure and CVD

Measuring obesity

Obesity - being very overweight and having too much body fat

Body mass Index (BMI)

BMI = mass(kg) / height squared (m)

Below 18.5 = underweight

18.5 - 24.9 = normal

25 - 29.9 = overweight

30 - 39.9 = moderately obese

above 40 = severely obese

BMI isn't always reliable as it doesn't take account for muscle mass

Treating CVD

What is CVD?

disease of the heart and blood vessels

Arteries narrow when fatty deposits build up inside them

Deposits can also trigger blood clots to form

Lifestyle changes

Balanced diet

Withdrawal from alcohol and smoking

Exercise regularly

Disadvantages

Long term

Sudden change in lifestyle may not be safe

Medication

Statins

Reduces the amount of LDL-Cholesterol in bloodstream

Statins slow down the rate of fatty deposits forming

Reduces risk of strokes and heart attacks

Disadvantages

Muscle pain

Weakness

Bad reactions can make people reluctant to take them

Antihypertensives

Reduce blood pressure

Helps prevent damage to blood vessels, reduces risk of fatty deposits forming

Types

Diuretics - flush out excess water

ACE inhibitors - relax blood vessels

Beta Blockers - cause the heart to beat slower

Disadvantages

Side effects like headaches and dizziness

Anticoagulants

Make blood clots less likely to form, less chance of heart attacks

Warfarin reduces fibrin production

Disadvantages

Slow to take action

Patients can suffer excessive bleeding

Risk of internal bleeding

Surgical procedures

Stents

Wire mesh tubes can be inserted into arteries to widen them and keep them open

Keep coronary arteries open, making sure blood can pass through

Surgery is simple and relatively quick

Disadvantages

Risk of complications

May need to be replaced

Risk of blood clot developing

Patient needs to take anticoagulants

Coronary bypass surgery

A piece of healthy vessel taken from elsewhere in the body is used the bypass a blocked section of the coronary arteries

Disadvantages

Coronary bypass surgery is longer and more invasive that stent surgery

long recovery time

Donor hearts

If heart disease is severe, the whole heart can be replaced

Disadvantages

Severe shortage of suitable donor hearts

Potentially dangerous operation

Risk of rejection by the immune system

Specific bacteria are only killed by a specific antibiotic

Genes

Differnet alleles of a gene may be more prone to mutation or how well you absorb nutrients

These factors could be more common in particular ethnic groups

Environmental

Air pollution can cause lung disease

Posions in food and drink can damage the body

Malnutrition - when a person eats to much or too little of a nutrient, this could lead to deficiency diseases or obesity

Used to treat bacterial infections