Immunology Flashcards
1
Q
What is immunology?
A
-concerns the immune system and how it protects the body.
-studies an organisms response to invasion by foreign microbes and their products
2
Q
What is disease?
A
The body acting as a host to other living organisms
3
Q
What organisms live on or in the body?
A
microbes such as fungi, protoctista and bacterial species.
4
Q
how do organisms that live in/on the body cause disease in a parasitic relationship?
A
by secreting toxins
5
Q
how do some organisms contribute to our health and defend us from disease?
A
in a symbiotic or mutualistic relationship
6
Q
What is an example of an organism that that may contribute to our health?
A
Escherichia coli in the large intestine synthesises vitamin K, which is absorbed by the body.
7
Q
How might E.coli benefit from humans?
A
human body provides E.coli with a safe, enclosed, and comfortable living environment in which the bacteria receive the required nutrients (sugars) for reproduction and growth.
8
Q
How can DNA be infected?
A
by dna viruses called bacteriophages
9
Q
What is susceptibility to pathogens?
A
a property of life, as one organism provides a habitat for another
10
Q
What are the important diseases?
A
-Malaria
-Cholera
-TB
-Flu
-small pox
11
Q
What is the site of infection and symptoms of cholera?
A
-Toxins affect the human gut lining causing a watery diarrhoea, severe dehydration and frequently death
12
Q
What is the mode of transmission for cholera?
A
-Humans act as reservoirs/carriers and can contaminate water supplies with the pathogen.
-The pathogen=transmitted by drinking contaminated water, although it only multiplies in the human host.
13
Q
What is prevention and control for cholera?
A
-Treatment of waste water, good hygiene and provision of clean drinking water.
-Vaccine (killed organism or possibly genetically engineered) may provide temporary protection
14
Q
What is the treatment for cholera?
A
Antibiotic treatment is possible but oral rehydration is the main method of treatment
15
Q
What is the site of infection and symptoms of TB?
A
-Most commonly affects lung and neck lymph nodes.
-Symptoms include coughing, chest pain and coughing up blood.
16
Q
What is the mode of transmission of TB?
A
-can be spread rapidly in overcrowded conditions and is transmitted in airborne droplets through coughing and sneezing of infected individuals in close proximity.
(On the increase, partly due to the link with the HIV epidemic.)
17
Q
What is prevention and control for tb?
A
BCG vaccination programme for children.
18
Q
What is the treatment for TB?
A
A long course of antibiotics.
19
Q
What is the site of infection and symptoms of small pox?
A
Small blood vessels of the skin, mouth, throat and lungs causing a rash and blisters.
30 to 60% fatality rate
20
Q
What is the mode of transmission for smallpox?
A
Airborne droplets of infected individuals in close proximity.
21
Q
What is prevention and control for smallpox?
A
-extinct due to immunisation programmes
-was possible due to low rates of antigenic variation/mutation.
-also there was no animal reservoir and people were keen to be immunised because of the devastating effects of the disease.
22
Q
What is the treatment for small pox?
A
N/A
23
Q
What is the site of infection and symptoms of influenza?
A
Upper respiratory tract, causing a sore throat, coughing and fever
24
Q
What is the mode of transmission for the flu?
A
Airborne droplets through coughing and sneezing of infected individuals in close proximity.
25
What is the prevention and control for the flu?
-Quarantine and hygiene but difficult to control.
-Annual vaccination programmes, but due to new types this is not always effective.
26
What is the treatment for the flu?
-Antibiotics=ineffective against influenza and are only used to treat the symptoms of secondary bacterial infection.
-Rest, keep warm, drink plenty of fluids and take painkillers.
27
What is the site of infection and symptoms for malaria?
-Liver cells and red blood cells, causing them to burst when more parasites are produced.
-Symptoms=severe bouts of fever and flu-like illness, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhoea may also occur.
28
What is the mode of transmission for malaria?
By a vector - a female mosquito from the genus Anopheles when feeding on blood
29
What is prevention and control for malaria?
-Knowledge of life cycles. Nets, clothing & repellent.
-Vaccines difficult to develop.
-Drug treatment to reduce the chances of infection.
30
What is the treatment for malaria?
Drugs that affect Plasmodium outside cells are available but limited success and have side effects.
31
What is malaria in some sub tropical regions?
endemic
32
What is malaria caused by?
a single celled parasite called of the genus Plasmodium
33
What kingdom does the malaria parasite belong to?
protoctista
34
How many different species of plasmodium may cause malaria?
5 different species
35
What species of plasmodium causes the most deaths?
plasmodium falciparum
36
What species of plasmodium is also a major killer?
plasmodium viax
37
What is plasmodium transmitted by?
by a species of mosquito in from the genus anopheles (mosquito vector)
38
When does the transmission of plasmodium occur?
when the infected mosquito pierces the skin of a human to take a blood meal
39
Why are only the adult females vectors the plasmodium parasite?
as these feed on human blood and so can transmit the parasite from human to human.
40
What host is the adult female mosquito?
primary host but doesn’t suffer from the presence of the parasites
41
What host may humans be considered as and what symptoms of infection do they show?
-Secondary
-Severe bouts of fever and flu-like illness, headache, muscle aches, and tiredness. Nausea, vomiting, and diarrhoea may also occur.
42
Why are male mosquitos not vectors of the Plasmodium Parasite?
-Male mosquitoes feed on the nectar of plants to get sugar.
-Do not feed off human blood like females
43
What is the life cycle of malaria?
-infected mosquito takes a blood meal and the plasmodium parasite enters blood stream
-Plasmodium travels to, and then invades liver cells, where the parasite matures
-Liver cells rupture and release plasmodium parasites, then invade red blood cells and multiply asexually. RBC’s then also rupture, releasing more plasmodium, which invade other RBC’s. The rupture of red blood cells results in severe fever.
-If a female mosquito were then to feed on the blood of an infected individual the Plasmodium parasites infect the mosquito, which act as a vector to pass the disease onto another host.
44
What does prevention of malaria rely on?
knowledge of the life cycle of both the vector (mosquito) and the parasite (Plasmodium)
45
What are the preventative measures of malaria (responding to mosquito behaviour) ?
-Sleep under nets
-Nets are treated with the pyrethroid insecticide
-Spray indoor walls with insecticide
-Drain or cover stagnant water e.g. water tanks, ponds
-Film of oil on the water
46
What is the reason for effect for sleeping under nets?
Mosquitos feed at night, prevents mosquito biting
47
What is the reason for effect for nets being treated with pyrethoid insecticide?
Pyrethroid kills mosquitos (the vectors for plasmodium)
48
What is the reason for effect for spraying indoor walls with insecticide?
Kills mosquitos as they rest on walls after feeding
49
What is the reason or effect for draining or covering stagnant water e.g. water tanks, ponds?
Removes female mosquitos access to egg-laying sites
50
What is the reason for effect for putting a film of oil on the heater?
Prevents larvae piercing surface to obtain oxygen
51
What are the biological control preventative measures?
Fish introduced into water
Infecting mosquitos with bacterium
Male mosquitos sterilised with X-rays
52
What is the reason for effect for fish being introduced into water?
Larvae are aquatic: fish eat them
53
What is the reason for effect for infecting mosquitos with bacterium?
Bacteria infection blocks plasmodium development in the mosquito
54
What is the reason for effect for sterilising male mosquitos with X-Rays?
After they mate with females no offspring are produced
55
What type of treatment is available for malaria?
drug treatment, but mainly to reduce the chance of infection
56
Why have malaria vaccines been proved difficult to develop?
The Plasmodium parasite has high mutation rates and there are many antigenic types.
57
What are viruses outside of the host cell described as?
being inert, are essentially particles and have no metabolic pathways.
58
When can viruses only replicate?
once inside a host cell, where the enzyme machinery of that host cell is hijacked to make more viral copies
59
What are the two main types of reproduction cycle viruses can b grouped into?
lysogenic cycle or the lytic cycle.
60
What happens in the lytic cycle?
-viruses immediately reproduce using the host's metabolism to copy their nucleic acid and synthesise new coat protein (capsid).
-new viral particles (virions) have assembled in the host cell cytoplasm
61
What happens once new viral particles have been assembled in the host cell cytoplasm?
they will leave the host cell (so they can then infect new cells) in one of two ways:
-Lysis of the host cell e.g. common cold virus
-Budding from the host cell surface (where the virus becomes enclosed by part of the host cell membrane) e.g. influenza virus
62
What happens in the lysogenic cycle (happens before last step of cell lysis)?
-following penetration of the host cell and shedding of the capsid, the viral nucleic acid is integrated into the host cell genome and may remain there for many cell generations with no clinical effect.
-virus then enter the lytic cycle at some time later. which is when symptoms are produced e.g. Herpes simplex virus. HIV virus.
63
How can viruses be pathogenic (sometimes resulting in death of the host cell)?
Cell lysis
Production of toxic substances
Cell transformation
Immune suppression
64
What is cell lysis?
when viruses escape from cells to infect other cells / organisms (shedding)
65
What is cell transformation?
-viral DNA can integrate into the host chromosome.
-If the DNA inserts into a proto-oncogene or tumour suppressor gene it can result in the cell undergoing rapid and uncontrolled cell-division i.e. becoming cancerous.
66
How is HIV made?
viral DNA transcribes mRNA; and new viral RNA;
mRNA carries code for amino acids as triplets of bases/codons; to ribosomes; viral protein assembled;
viral protein and viral RNA assembled into new virions/virus particles;
67
What is the definition of an antibiotic?
A substance produced by a fungus which diminishes the population growth of bacteria
68
What is the mode of action for antibiotics?
Bacteriostatic - prevent the population growth of bacteria
Bactericidal - kill bacteria
69
What do antibiotics act and not act on and what does this mean?
-on bacteria, but not on eukaryotic cells or viruses.
-therefore treat bacterial infection without harm to the patient.
70
What do broad spectrum antibiotics do?
act against a wide range of disease-causing bacteria by targeting both gram-positive and gram-negative bacterial groups.
71
What do narrow spectrum antibiotics do?
-are active against a selected group of bacterial types
-they can act on either gram-positive or gram-negative but not both
72
what is the structure of the bacterial cell wall?
-Contains peptidoglycan consisting of molecules of polysaccharide cross-linked by amino acid side chains- provides strength and prevents osmotic lysis.
-In some bacteria this cell wall is surrounded by an outer layer of lipopolysaccharides.
-The Gram stain reaction highlights cells with this additional layer (Gram negative) and they retain a counter stain and appear pink/red.
-The presence of this extra layer provides Gram negative bacteria with protection from some antibacterial agents such as lysozyme and Penicillin.
73
What is tetracycline?
-a broad-spectrum, bacteriostatic antibiotic that affects protein synthesis
-both Gram - and gram + carry out protein synthesis
74
What does tetracycline do?
-blocks the 2nd tRNA binding site in the large subunit of bacterial ribosomes, preventing the binding of a tRNA molecule’s anticodon to its complementary codon
75
What effect does tetracycline have?
In this way tetracycline inhibits the translation stage of protein synthesis
76
What is penicillin?
a narrow-spectrum, bacteriostatic antibiotic
77
What does penicillin do?
-affectes the formation of cross-linkages in the peptidoglycan cell wall during growth and division of bacterial cells
by binding to and inhibiting the enzyme (transpeptidase) responsible for the formation of these cross-linkages.
-it binds irreversibly to transpeptidase and it is not complementary to the active site of this enzyme.
-The enzyme's function is permanently altered.
78
What type of inhibitor is penicillin?
-a non-competitive inhibitor, as binding is irreversible.
-also penicillin has a shape that is not complementary to the active site.
79
Penicillin causes the cell wall to be weakened, what effect would this have if the cells were placed in a hypotonic solution?
-The bacterial cell will gain water by osmosis and the cytoplasm will swell.
-Eventually the cell will lyse as the cell wall is not strong enough anymore.
80
Why are gram positive bacteria more susceptible to penicillin?
due to their thick peptidoglycan cell wall
81
why is penicillin less effective against gram negative bacteria?
only have a thin peptidoglycan cell wall and contain the outer lipopolysaccharide layer
82
Why are viruses not affected by antibiotics?
Viruses have no cell wall or metabolic pathways to disrupt.
83
what are two sources of antibiotic resistant alleles?
-Bacteria divide under optimum conditions and have a high mutation rate. Naturally occurring mutations that confer resistance to antibiotics have given these bacteria a selective advantage in the presence of antibiotics.
-Plasmids containing the antibiotic resistance allele can be transferred from one bacterium to another via conjugation.
84
what has overuse of antibiotics resulted in?
the accidental selection of bacterial strains that are completely unaffected by some antibiotics
85
What happens if there are no antibiotics in the environment?
-having this resistance would not provide the bacteria with a selective advantage over bacteria without resistance.
-Therefore, resistant bacteria only have a selective advantage when the antibiotic is present, and so overuse of antibiotics selects for these bacteria and the frequency of the resistance allele increases.
86
What shows antibiotic resistance?
Several clinically important bacteria including those causing leprosy, TB and gonorrhoea
87
What bacteria are resistant to several antibiotics?
-MRSA = Methicillin-resistant Staphylococcus aureus
-Clostridium difficile
88
What does the immune system do to the body?
enables it to resist disease.
89
What is there to protect the body against pathogens?
physical barriers
90
What happens if physical barriers fail?
there are then chemical and cellular responses.
91
What must the body be able to do?
detect foreign (non-self) antigens and distinguish them from self antigens in its own tissues.
92
What are the natural barriers and non specific (passive) immune responses?
Ciliated mucous membranes:
Localised inflammation
Blood clotting
Skin
Tear ducts, saliva and stomach
Phagocytosis & Antigen Presenting cells:
Natural skin flora
93
How does blood clotting help?
If capillaries are broken, blood clots to seal wound.
94
How do tear ducts, saliva and the stomach help?
Lysozyme in tears and saliva hydrolyse peptidoglycan cell walls to kill bacteria. Stomach acid kills many bacteria
95
how do ciliated mucous membranes help?
-Inhaled air is a source of microorganisms.
-Mucus traps them and cilia on ciliated epithelial cells waft to bring the mucus up and out of the trachea.
96
What do cilia in the nose do?
filter air and trap dust particles but no mucus is produced
97
What does localised inflammation do?
localise breaks in the barrier (e.g. skin)
98
How does the skin help?
tough barrier and vitamin C is required to maintain strong connective tissue contains keratin and collagen
99
How does skin flora help?
-Bacteria and fungi found on our skin offer competition for pathogenic bacteria.
-These natural flora don't wash off the body as easily as pathogenic bacteria
100
how does phagocytosis and antigen presenting cells help?
-phagocyte engulfs a bacterium, enclosing it in a vacuole.
-Lysosomes fuse with this vacuole releasing hydrolytic enzymes that destroy the bacteria.
-These can then add the antigens to their own membrane becoming an Antigen Presenting Cell supporting the specific immune response
101
What does the body produce to a foreign antigen?
body produces a specific response (lymphocytes provide this response)
102
What are lymphocytes?
Subgroup of leucocytes (WBCs) that are produced from stem cells in the bone marrow
103
what are the two components to the specific immune response?
the humoral response and the cell mediated response.
104
where do b lymphocytes originate from?
(humoral response)
stem cells in the brown marrow and mature in the speen and lymph nodes
105
What is do millions a of different b cells do?
circulate in the blood stream and lymph vessel.
-each has specific receptor on its surface which bind to one type of antigen
106
What happens when a foreign antigen enters the blood or lymph vessels? (humoral response)
-B lymphocytes bind to the foreign antigens.
-The B cells become activated stimulating clonal expansion to form:
Plasma cells
Memory B cells
107
What do plasma cells do?
secrete antibodies specific to the foreign antigen
108
What do memory cells do?
which remain dormant in the blood circulation ready to rapidly divide by clonal expansion to form more B lymphocytes if the same antigen is encountered in the future
109
What are antibodies?
Y shaped globular proteins (immunoglobulins, often given the symbol Ig).
110
What is each antibody molecule made from?
four polypeptide chains and has two antigen binding sites
111
What is each antibody specific to?
the antigen to which they bind, forming an antigen-antibody complex
112
What happens when antibodies bind to the antigen and form an antigen-antibody complex?
they render the antigen inactive, by processes such as agglutination (the clumping together of bacteria)- allows mecrophages (phagocytes) to locate and engulf the pathogens
113
What is the highest level of protein structure and antibody has?
quaternary
114
What type of bond (covalent) holds the polypeptide chains together between sulphur containing variable groups?
Disulphide bridges
115
how does the structure of an antibody ensure it only binds to one type of antigen?
The variable region is only complementary to one type of
116
What happens in agglutination and what does the do?
-microbes are clumped together.
-allows them to be destroyed (e.g. by phagocytosis) more efficiently
117
how is the structure is of an antibody adapted to help agglutination to occur?
As there are two light chains the antibody can bind to two antigens at once
118
What happens when a foreign antigen enters the blood or lymph vessels (process of humoral response)?
-B lymphocyte with a specific receptor binds to the specific antigen on the pathogen- stimulates the B lymphocyte to divide by mitosis
-CLONAL EXPANSION
Plasma cells
b lymphocyte memory cells
119
What do plasma cells do in humoral response?
-Secrete antibodies specific for to the antigen
-antibodies clump pathogens together (agglutination)- prevents them infecting cells/producing toxins and allow phagocytosis cells to engulf them in phagocytosis
120
what do b lymphocyte memory cell do in humoral response?
-Remain dormant in the blood and if the same antigen is ever encountered again they will bind and are stimulated to divide by mitosis to form many plasma cells
121
where do t lymphocytes originate from? (cell mediated response)
stem cells in the bone marrow, but are activated in the thymus gland.
122
What happens when a phagocyte (such as a macrophage) engulfs a pathogen?
(cell meditated response)
-pathogen is hydrolysed into component parts
-phagocyte can then present some of these parts (antigens) on its membrane surface.
-This phagocyte is now an antigen presenting cell.
123
What are other cells that can prevent antigen on their surface to become antigen presenting cells? (cell mediated response)
- B lymphocytes and infected body cells
124
What happens when a t lymphocyte detects a specific antigen in an antigen presenting cel?
it is stimulated to undergo clonal expansion.
T
125
What does a t cell clonal expand into?
t helper
t memory
cytotoxic t (killer)
126
What does the t helper cell do?
produce chemicals called cytokines
127
what do cytokines do?
(chemicals produced by t helper cells)
-Stimulate more phagocytic cells to migrate to the infected tissue, which then engulf more of the pathogens and digest them
-Stimulate clonal expansion of plasma B cells to make and secrete antibodies specific to that particular antigen
128
What does a t memory cell do?
Remain dormant in the circulation and then divide rapidly by clonal expansion to form more T lymphocytes if the same antigen is encountered in the future.
129
What does a t memory cell do?
Remain dormant in the circulation and then divide rapidly by clonal expansion to form more T lymphocytes if the same antigen is encountered in the future.
130
what does a cytotoxic t cell (killer) do?
Destroy infected body cells (that have specific antigens on their surface) by lysing the cells. E.g a normal body cell infected by a virus
131
What is the process of cell mediated responses?
-lysosomes release hydrolytic enzymes to digest the pathogen
-The phag displayed part of the pathogen on its surface and becomes an antigen presenting cell
-B- lymphocytes and infected body cells can also present parts of a pathogen on their surface and become antigen presenting cells
-T lymphocyte with a specific receptor
binds to a specific antigen. It is stimulated to divide by mitosis.
-clonal expansion into helper, memory and killer
132
What is the primary response?
-on first exposure to the antigen, there is a latent period.
phag engulfs the foreign antigen/cell/virus.
-The phag incorporates part of the antigen on its own cell membrane B cells and infected body cells also present antigens.
These antigen-presenting cells activate specific T cells which undergo clonal expansion to form helper T cells which release cytokines.
Cytokines stimulate B cells to undergo clonal expansion forming many plasma B cells which start secreting antibodies against the antigen. Memory cells are also produced.
A B lymphocyte with a specific receptor can also bind to an antigen on the pathogen and is stimulated to undergo elenal expansion.
Antibodies are specific to the antigen and bind to it, holding the pathogen in place (agglutination).
The B plasma cells to secrete a low level of antibodies for about 3 weeks, after which the infection usually subsides (this time period can vary).
133
why is the latent period is much shorter and the antibody production much greater in the secondary immune response?
On re-exposure to same antigen, after a very short latent period, memory cells undergo rapid clonal expansion.
A small amount of antigen stimulates rapid production of plasma B cells.
Antibodies are made much more quickly and more concentrated than in the primary response.
The antibodies remain at high concentrations for longer and no symptoms develop.
134
What happens in passive immunity?
the body may receive antibodies that have been produced by another individual
135
why is protection short lived in passive immunity?
-antibodies are recognised as non-
self and are destroyed and no memory cells are produced
136
what are examples of passive immunity?
-when antibodies are transferred to the foetus via the placenta, or to the baby in breast milk.
-Artificial when pre-synthesised antibody is injected into an individual e.g. tetanus antitoxin
137
What happens in active immunity?
the individual produces their own antibodies
138
why is protection long lasting in active immunity?
due to the production of antigen-specific memory cells.
139
what are examples of active immunity?
Natural production following infection
Artificial production following vaccination e.g. against Rubella.
140
What are natural and artificial active immunity antibodies?
-natural- infection
-artificial- vaccination
141
are memory cells produced in a the immunity?
yes, b and t
142
what are artificial examples of active immunity?
Rubella
Influenza
Measles
Mumps
143
What are natural and artificial passive immunity antibodies?
Natural- anitbodies are passed to
the foetus through the placenta or the baby in breast milk
Artificial- monoclonal antibodies are injected
144
Are memory cells produced in passive immunity?
No, memory cells are not produced
145
what are artificial examples of passive immunity?
Tetanus
Hepatitis
Rabies
Ebola
146
In an emergent what can antibodies do and what does this allow?
-be injected to provide rapid protection against a pathogen, e.g. in cases of rabies.
-allows time for a person's immune system to develop an active immune response.
147
what are injections of antibodies also used with?
people who do not develop a strong immune response to a vaccination or who have a weakened immune system.
148
what can vaccines be?
-Weakened or “attenuated” versions of the pathogen
-Inactive or killed pathogen
-Inactivated toxin
Antigens isolated from the pathogen.
149
How do vaccines work?
-Often, a weakened inactive form of the pathogen is injected into an individual.
-Specific antigens on the pathose will be detected by specific B and T
-B and T cells will undergo colonal expansion, triggering an immune response.
-The individual may show some
symptoms as their body will undergo a normal immune response to the weakened pathogen.
-As part of this response, cells will be produced.
-If the same antigen is ever encountered in the future memory cells will undergo rapid clonal expansion.
-The pathogen will be destroyed before it can produce any symptoms so the person is said to be immune
150
What are features of a successful vaccine?
-safe/no side effects.
-effective/trigger an immune response.
151
What type of pathogens are more like to to be protected by a single round of immunisations?
Pathogens that exhibit no or low levels of antigenic variation (e.g. Rubella)
152
What pathogens are more difficult to be protected?
Pathogens that have many antigenic types and mutate frequently
153
What does production against pathogens that have many antigenic types and mutate frequently require?
require repeated immunisation against the most common antigens, however even this isn't always effective.
154
What does protection against pathogens that have many antigenic types and mutate frequently require?
require repeated immunisation against the most common antigens, however even this isn't always effective.
155
what type of individuals works he offered flu vaccines in the NHS in the uk?
Older people/ immunocompromised/ people with asthma.
156
how often are there individuals offended flu injections?
-Annually - there are many antigenic types of influenza and new types are always occurring due to high mutation rates.
-Annual vaccinations contain a few strains that are predicted to be the most prevalent that year.
157
how often are there individuals offended flu injections?
-Annually - there are many antigenic types of influenza and new types are always occurring due to high mutation rates.
-Annual vaccinations contain a few strains that are predicted to be the most prevalent that year.
158
what happens if enough people in a population are vaccinated? (herd immunity)
the spread of disease is controlled so even people who are not vaccinated have some protection
159
what does herd immunity rely on?
a certain proportion of the population being vaccinated.
160
what happens if the number of people vaccinated falls below critical level? (herd immunity)
disease may be able to spread.
161
What are the ethical considerations for vaccination programmes?
-The rights of the individual when considering mandatory compared to voluntary programmes
-Cost vs effectiveness of the vaccine.
-Side effects, whether real or perceived.
-Protection of the individual compared to the protection of the community.
162
What must happen when a new vaccine/drug is developed?
needs to be trialled to ensure it is safe and effective.
163
What does clinical trials involve?
first testing a new drug on a small number of healthy individuals to find out a safe dosage and look for side effects.
164
What criteria should be used to select the participants for the clinical trial to ensure the results are valid?
Different age groups , different ethnicities, different genders, medical history, other medication, diets, body compositions
165
what is the drug then tested in after clinical trials?
The drug is then tested on a larger group of patients to see how well it works
