part 2 Flashcards
(196 cards)
1
Q
what is cannabis extracted from?
A
- extract from Cannabis sativa plant….a member of the hemp family
2
Q
what can be produced using different parts of Cannabis Sativa?
A
- stalk - fibre used to make hemp
- dried flower + leaves - used to make marijuana
- resin - used to make hashish
3
Q
where did cannabis originate and how long was it cultivated for?
A
- Cannabis sativa originated in Central Asia
cultivated for at least 4500 years
4
Q
when did cannabis reach europe?
A
1500BC
5
Q
what is hemp and what was it used for in the past?
A
coarse, strong fibre extracted from the stalk
- listed in early pharmacopoeias as a medicinal/herbal plant
- early cultures believed cannabis possessed magical qualities
- used for religious and spiritual rituals to induce trance-like states
- more practical early use of hemp was to make paper
- declaration of independence was drafted on cannabis paper
6
Q
what did the de materia medica and central asian cultures state about hemp and it uses?
A
De Materia Medica:
* hemp capable of making “the stoutest cords”
* also notes its medicinal/psychoactive effects
Greek historians report central asian cultures burning hemp on heated stones:
* “as it burns, it smokes like incense and the smell of it makes them drunk”
*as early as 450 BC
6
Q
where are CB1 receptors located in the brain and what do these reigions do?
A
- Hippocampus
- Involved in memory
- Inhibited by cannabinoids
- Hypothalamus
- Involved in regulating appetite
- Inhibited by cannabinoid
- Cerebral cortex
- Involved in consciousness & sensory awareness
- Altered by cannabinoids
- Cerebellum
- Involved in co-ordination
- Inhibited by cannabinoid
- Brain stem/spinal cord
- Involved in pain, vomiting reflex & control of heart rate
- Inhibited by cannabinoids, (except heart rate)
6
Q
what aare the similarities between cannabinoids?
A
- all structurally very similar
- all stimulate very similar responses
- therefore they all must be acting on same cellular target (remember the opioids
6
Q
where is the cannabinoid receptor located and how does it work?
A
- receptor located on membrane of certain cells in the body
- cannabinoid binding to receptor is what triggers the effect of the drug
6
Q
what are the two types of cannabinoid receptors?
A
- CB1 found in brain
- CB2 found in periphery (outside brain)
most of the effects of cannabinoids result from binding to CB1
7
Q
do humans produce endogenous cannabinoids and why is this a question that should be asked?
A
- the fact we have receptors for cannabinoids in our body poses a question:
- do we produce our own endogenous (home-made) cannabinoids?
- the existence of these endogenous cannabinoids was discovered in 1992
7
Q
what is anandamide?
A
- anandamide:
- binds CB receptors
- mimics the effects of cannabinoids
7
Q
what are endocannabinoids?
A
these endogenous cannabinoids were isolated from slices of pig brain:
- the 1st to be isolated was called anandamide
- now 5 exist in total but there may be more that we havent discovered
- suggests that these compounds play an important role
- 2-arachidonoyl glycerol
- 2nd endocannabinoid discovered
7
Q
when did governments start banning cannabis and what were the consequences of doing so?
A
in the 1990s, this caused public outcry that peaked in the 1960s
8
Q
how common is cannabis usedb today?
A
~ 4% of World’s adult population have used it (162 million people)
~ 0.6% of World’s population are routine/regular users (22.5 million)
9
Q
what is cannabis made of and what are the three main constituents of cannabis?
A
cannabis preparations are crude cocktails of different lipid soluble molecules
- tetrahydrocannabinol (THC or Δ9THC) main active compound (most potent)
- cannabidiol (precursor for THC)
- cannabinol (spontaneous product of THC breakdown and therefore formed by THC)
10
Q
when was cannabis first isolated and identified?
A
1964
11
Q
how does THC affect the CNS?
A
- loss of short-term memory
- increased confidence
- reduced co-ordination
- catalepsy (unusual fixed, comatose poses)
12
Q
what is the relationship between THC proportion and activity?
A
the greater the proportion of THC, the greater the activity of the preparation
13
Q
Role of other cannabinoids?
A
- the other cannabinoids add other subtle effects & characteristics
- regional variation in the proportions of cannabinoids (Oriental vs USA)
14
Q
Do cannabinoid ratios differ within the plant?
A
yes, the ratio also differs in different parts of plant
THC in highest concentration in the resin, lowest in the stalk
this is again reflected in the how active the preparations are
resin generally higher activity than extract from other areas of the plant
15
Q
how can THC affect the digestive system?
A
- reduced nausea and vomiting
- stimulated appetite
16
Q
how does THC affect mood?
A
- relaxation
- sense of well-being
(“ethanol-like” effects, without the aggression) - sharpened sensory awareness
(sight and sound in particular)
17
Q
other than the CNS, Digestive system and mood, what else can THC affect?
A
- increased heart rate
- dilation (widening) of airways
- reduced pressure within the eye
18
what do endocannabinoids do?
* regulates heart rate
* widens (dilates airways)
* prevents nausea/vomiting
* stimulates appetite
* increases pain threshold
* decreases sensation of pain
19
what was cannabis used for in the past? (WW1)
* cannabis was used as a truth serum.
- developed by a US intelligence agency during WWII
- subjects were given THC-laced cigarettes and were found:
"to be loquacious and free in their impartation of information”
* used to interrogate an enforcer for Lucky Luciano (gangster & drug dealer)
- talked in detail about Luciano’s heroin operation
- on a 2nd occasion, a higher dose was tried & the enforcer passed out for 2 h
* based on ability to relax and distract subject with feelings of euphoria
- also tends to disrupt their memory of exactly what truths they may have told
19
what are some clinical applications of cannabinoid drugs? (1)
1. Activation of the cannabinoid receptor
- uses THC or a synthetic derivative called nabilone
being developed/investigated to treat:
- nausea and vomiting in cancer chemotherapy
- to reduce weight loss in cancer and AIDS (stimulates appetite)
- glaucoma (decreases pressure in the eye)
- multiple sclerosis (increases mobility, reduces pain)
- pain
- anxiety
20
what are some clinical applications of cannabinoid drugs? (2)
- uses a drug called rimonabant
- potential use in treating obesity:
- blocks endocannabinoid stimulation of appetite
21
what is diabetes?
Increase in blood glucose (sugar), either due to a lack of insulin (type 1) or to a lack of effect of insulin (type 2).
In ancient times physicians would drink their patients’ urine to see whether it tasted sweet, “mellitus” is Greek for honey, or tasteless “insipidus”, the other much rarer form of diabetes
22
what does insulin do?
Insulin allows muscle and fat tissue to take up glucose and use it to produce energy and store carbohydrate, protein and fat.
In type I and type 2 diabetes, glucose uptake by these tissues is impaired and so blood glucose rises (hyperglycaemia).
23
what can untreated type 1 diabetes lead to?
Untreated type I diabetes leads to many complex changes in the body which ultimately cause starvation and death.
24
before the discovery of insulin, what was the survival time of diabetes?
between 2 weeks and 18 months
25
who is the worlds largest producer of insulin?
August Krogh and Nordisk in Denmark, known now as Novo-Nordisk is the world’s largest producer of insulin
26
when was insulin introduced to britain?
1924
27
how much has the NHS spent on diabetes?
>10% of NHS budget is spent on treating diabetes and these diabetic complications.
28
what are the steps forward regarding diabetes?
Since insulin is destroyed by the gut, it has to be injected.
Recently, inhaled insulin was withdrawn because of unacceptable side-effects.
Stem cell technology offers hope for the future in repairing the pancreas and restoring beta cell function.
29
describe the discovery and development of viagra?
it was marketed in 1998 by Pfizer to treat erectile dysfunction
- sales of around £1billion per year
- partly why Pfizer is biggest pharmaceutical company in world
- also down to “luck”....they discovered Viagra “by accident
30
what is the drug name for viagra?
sildenafil citrate (Viagra)
31
What was Pfizer's medical objective in 1985, and what condition were they aiming to treat with a new drug design focused on vasodilation?
Pfizer set out to develop a new medicine to treat angina, a condition characterized by severe pain in the heart and chest wall due to insufficient blood supply from the arteries.
The goal for Pfizer scientists was to design a drug that would induce vasodilation, causing the arteries to dilate or open up, thereby increasing the blood supply to the heart and relieving the symptoms of angina.
32
What was the strategy behind Pfizer's target selection for developing a new drug to treat angina, according to the theory of vasodilation?
Pfizer's strategy in target selection for a new angina drug was based on the theory of vasodilation.
Scientists aimed to identify a target in the artery wall, specifically an enzyme responsible for halting natural vasodilation.
By inhibiting this enzyme, they theorized that they could enhance natural vasodilation, thus helping to keep the arteries dilated for longer periods and preventing angina. This process was intended to increase blood flow to the heart, thereby relieving the severe chest pain associated with angina.
33
how did Pfizer use the screening assay technique during the development of its vasodilation drug?
-Pfizer's drug looked to inhibit an enzyme which stopped natural vasodilation?
- scientists cloned the target enzyme
- designed an assay to measure the activity of the enzyme
- screened over 1500 compounds between 1986-1990
- looking for compounds that inhibited the enzyme -> this would fit their profile as a vasodilator
34
how did Pfizer use 3D modelling during the development of his vasodilation drug?
3D modelling
- also characterised the 3D shape of the target enzyme
- knowledge of this permits “design” of compounds that will interact with it
35
describe the clinical trial phase of viagra
- pre-clinical trials in animals showed no safety or toxicity issues- so UK-92480 entered Phase I trials in healthy volunteers
- the trials showed that the drug was safe and no toxic effects were reported....
- ....however, many male volunteers reported an “interesting” side-effect
-> increased frequency and duration of penile erection
36
what was Pfizer's Angina treatment later used for?
In 1992 Pfizer changed direction with UK-92480
- began to investigate it as a treatment for erectile dysfunction (ED)
- work with UK-92480 and angina continued, but it lacked sufficient potency
- failed to make it as a treatment for angina
- the erection-stimulating side effects saved Pfizer from losing a LOT of money!
37
what is erectile dysfunction?
Erectile dysfunction (inability to obtain or sustain an erection)
- often an indication of underlying disease/problem
38
how does viagra work?
- UK-92480 inhibits the target enzyme (prolongs natural vasodilation)
- it turns out that there are many subtypes of the target enzyme
- UK-92480 especially potent at inhibiting the enzyme subtype in penile arteries -> therefore it is most effective at promoting penile vasodilation & erection -> less specific and potent in treating angina
39
what does "drug tolerance" mean?
- decrease in pharmacological effects of a drug with repeated use
- results in requirement for increased doses to achieve same effect
- often accompanies dependence/addiction
40
define “withdrawal symptoms"
- adverse physical and psychological effects upon stopping taking a drug
- can last days, months or indeed years
41
what are some examples of substance abuse from the past?
* mushrooms - stoneage
-ate mushrooms for mind-altering effects
- persists today (magic mushrooms)
* Frog/Toad Venom - ancient tribes
- extracted frog/toad venom
- consumed for rituals & trance-like state
* Cojobano seeds - Taino people (prehistoric)
- ate seeds of the Cojobano tree
- reported out-of-body-type experience
42
what are examples of substance abuse that still exist today?
* Alcohol - brewing traced back as early as 8000 BC
* Opium - traced back to Egyptian times and before
* Cannabis - grown and in use for over 4500 years
* Cocaine - early South American civilisations
- habitually chewed Coca leaves
- “strength to the weary”
- “makes the unhappy forget their sorrows”
- these leaves are a source of cocaine
43
what did early civilisations believe addiction to be and what does this tell us about human nature?
illness, madness, habits, weakness, possession by evil spirits
- illustrates that addiction is part of the core of human behaviour
- its causes and consequences are nothing new
- humans will develop dependencies on anything that makes them feel good
44
what are addictive drugs also known as?
* they are all so-called hedonic drugs
- people associate the effects of these drugs with pleasure (hedonic effect)
* pleasure is a basic human “reward” mechanism
- designed to reinforce basic survival behaviours (eating, drinking, reproducing)
* the pleasurable effects of these drugs tends to drive humans to repeat it so the cycle of drug abuse and addiction begins
- all of them activate the reward pathway
45
what does the reward/pleasure pathway do and how is it regulated?
* releases a compound called dopamine (the pleasure chemical)
- responsible for humans feeling pleasure or reward
* activation of the pathway releases dopamine into many areas of the brain
- this is what we feel as pleasure
* activity is controlled down by inhibitory nerve cells
- prevents the reward pathway releasing dopamine all of the time
46
what are examples of natural rewards and how does this relate to the reward pathway?
* natural pleasure (sex, shopping, sport, opera etc)
* stimulates release of endogenous opioids (enkephalins…Kosterlitz)
- these inhibit the inhibitory inputs
- therefore activate the pleasure pathway (and we feel pleasure)
47
what is an exampleof unnatural pleasure and how is it related to the reward pathway?
drugs of abuse all have different modes of action throughout the brain
- but they also all affect the reward pathway
- do so in 1 of 2 ways:
1. Inhibit inhibitory inputs……….OR
2. Directly stimulate the pleasure pathway
- both strongly activate the reward pathway to produce dopamine
- produces the “rush” or “hit” associated with drug abuse
48
what are the consequences associated with unnatural reward?
* leads to addiction
* repeatedly taking the drug (which users become compelled to do)
- brain down regulates the reward pathway (less sensitive to drug stimulation)
- protective mechanism against abnormal levels of stimulation
- this means larger doses of drug required to stimulate the pathway (tolerance)
* also means pathway rarely activated without drug
- in absence of drug, user feels depressed and ill (withdrawal)
- further compulsion to relapse and take drug
49
what are some examples of non-chemical addictions and how do they work?
examples: sex, gambling. theft, risk
* these all activate the reward pathway (to a lesser degree than drugs of abuse)
- engaging in these activities excessively and repetitively
- excessive, abnormal stimulation of reward pathway
- brain down regulates the pathway (tolerance)
- more and more of these activities needed to gain reward (addiction)
- not continuing with these activities means little or no pathway activity
- depression and illness (withdrawal)
50
how do different drugs cause varying levels of dependency?
more potent -> more pleasure -> more regulation of the pathway -> more urge to take the drug -> increase in severity in withdrawal symptoms -> more likelihood of relapse
51
what is physical dependence?
* associated with down regulation of reward pathway (tolerance)
- also depends on down regulation of other specific targets of the drug
- this is why withdrawal varies from drug to drug
- lasts days–weeks
52
what is psychological dependence?
* results from the fact the brain has “learned” to connect drug with reward
- produces “craving”
- often stimulated by association
e.g. seeing a cigarette, syringe or wishing to smoke/drink when socialising
- long lasting, main reason for relapse
53
what drug type causes the worst withdrawal symptoms?
most severe is opioid withdrawal
54
is drug addiction genetic?
- emerging evidence that susceptibility to addiction might be partly genetic
- research ongoing, however not yet clear which genes are involved
55
why is the use of cannabis in medicine controversial?
- long term usage may induce psychological (or other) problems
- the “gateway theory” suggests that use of cannabinoids may stimulate needs for stronger, more addictive drugs
56
what are the 5 treatments for addiction?
1. Short-term Substitution
- designed to lessen withdrawal and make it more bearable
- helps break habit and re-establish control
- reduces chances of relapse
e.g.
methadone – softens opioid withdrawal
diazepam – softens alcohol withdrawal
3. Blocking responses
- designed to prevent the problem drugs having an effect
- tends to involves blocking the specific target of the drug
- helps prevent relapse, as taking drug will have little or no effect
- tends to be used when addict is making good progress
e.g.
can block opioid effects
can block nicotine effects
4. Aversion therapies
- designed to produce an unpleasant response to drug
- discourages relapse
- helps to associate drug with unpleasantness
- “unlearns” association with pleasure
e.g.
alcohol aversion therapy - induces violent nausea/vomiting in response to alcohol
5. Psychological therapy
- therapies 1-4 are all pharmacological
- psychological therapy also vitally required
- helps “unlearn” drug taking behaviour
- helps to understand and deal with craving
- effectively addresses the long lasting psychological dependence
- aims to help with moving forward and reducing chances of relapse
57
what is blood made of?
white blood cells, plasma, platelets and red blood cell
58
what does blood do?
1. Carries oxygen to our cells where they use it to produce energy (RED BLOOD CELLS)
2. Carries hormones, enzymes, nutrients and waste products around the body (PLASMA)
3. Clots blood to prevent blood loss following injury (PLATELETS)
4. Defends us from infection (WHITE BLOOD CELLS)
5. Helps regulate body temperature
6. Maintains pH of body fluids
59
who was Richard Lower?
1665: performed first recorded successful blood transfusion in dogs
1667: performed first successful blood transfusion in humans.Sheep-human transfusion in attempt to cure insanity
60
who was James Blundell?
1818: performed first successful human-human transfusion§
61
who was Karl Landsteiner?
1901: observed that often, but not always, blood transfusion would results in blood clumping in the recipient’s circulation
1909: classified the ABO system of blood typing
1940: identified the rhesus antigen
62
what is the history of blood transfusions?
Initially blood was transfused
direct from human to humanIn
1913 Edward Lindeman discovered blood could be extracted by needle from the donor and injected into the recipient, allowing the volume of transfusion to be accurately monitored.
Blood transfusion became extensively practiced out of need during World War One
63
what are the 8 blood types?
A+ B+ AB+ O+A- B- AB- O-
64
what is an antigen?
marker on a cell surface that confers information about acells identity to the immune system.
65
what are antibodies?
produced by B lymphocytes which are primed to recognise specific antigenic markers on cells.
If lymphocytes recognise the antigen as “self” they ignore the cell.If lymphocytes recognise the antigen as being “non-self” they trigger an immune response to destroy the antigen-expressing cell.
66
how are blood typing and antigens related?
Antibodies bind with antigens to cause clumping of blood cells (agglutination) in vitro and haemolysis in vivo.
People with type A blood circulate antibodies for B antigen, People with type B blood circulate antibodies for A antigen
People with blood type AB have neither A nor B antibodies
People with blood type O circulate both anti-A and anti-B antibodies.
67
what happens if type A blood is transfused to someone with type B blood?
1) Donor B antibodies attack recipients RBC’s which have B antigen(in practice diluted to such an extent - negligible)
2) Recipients A antibodies attack donor RBC’s which have A antigen
68
why is ABO grouping important when doing blood transfusions?
Type AB+: no antibodies therefore universal recipients (can receive from any ABO or Rh type) although can only donate to other AB+ individuals.
AB- individuals can receive any Rh- blood but not Rh+. As well as considering ABO grouping must also take into account Rh group too.
Type O- : no antigens therefore universal donors (can donateto any ABO or Rh type) although can only receive from O-.O+ can donate to any Rh+ recipient but not Rh
69
what is a stem cell and what is proliferation and differentiation?
A stem cell can be defined as a cell that has the unique ability to make a choice between proliferation and differentiation.
Proliferation will maintain the pool of stem cells (self-renewal), while differentiation (when opportunely stimulated) will allow the formation of more specialised cell types..
70
what are the types of stem cells and where can they be found?
Several levels of“potency”= how broada stem cells differentiation potential is:
Totipotency: Fertilized egg
Pluripotency: Embryonic stem cells Multipotency: Somatic stem cells Unipotency: Precursor cells
71
describe the development of embryonic stem cells?
fertilised egg -> few celled embryo -> blastocyst -> harvested inner cell mass -> embryonic stem cells
72
what can pluripotent stem cells be used for?
Pluripotent stem cells have a number of potential uses such as developmental biology, regenerative medicine and pharmacology
73
how are iPSCs made?
There are only two ingredients to making iPSCs:
1) cells from a donor; typically these are skin fibroblasts, but you can use any terminally differentiated cell.
2) reprogramming factors,also known as Yamanaka Factors, typically OCT4,SOX2, c-Myc and KLF4; these are normally delivered using viral particles (process known as transfection)
74
What are multipotent stem cells?
Multipotent stem cells have the ability to differentiate into multiple cell types,but cell types of the same organ or tissue
Multipotent stem cells are also known as somatic stem cells, and they are present in the adult
They are one of the reasons we are alive, as they help us repair on a daily basis
They are normally contained within a "niche", and they are often quiescent until there is some damage or insult
They are relatively rare within tissues, and they are quite dicult to nd (aslosing them could mean )
75
what are some examples of adult stem cells?
* neural stem cells
* mesenchymal stromal cells
* hematopoietic stem cells
* muscle stem cells
76
What is Rhesus (Rh) grouping in blood, and what implications does it have for pregnancy?
Rhesus grouping refers to the presence (+) or absence (-) of the Rh antigen on red blood cells (RBCs).
If RBCs express the Rh antigen, the blood is Rh positive (Rh+ve); if the RBCs lack the Rh antigen, the blood is Rh negative (Rh-ve).
In pregnancy, an Rh-ve mother carrying an Rh+ve baby can be sensitized to the Rh antigen at parturition (birth), leading her to produce Rh antibodies.
While this typically doesn't affect the firstborn Rh+ve baby, it can be potentially fatal for future Rh+ve babies due to Hemolytic Disease of the Newborn (HDN). This condition can be prevented by the administration of anti-Rh antibodies to the mother.
77
what are the properties neural stem cells?
* self renewal
* lineage commitment and differentiation
* quiescence and activation
78
what are the properties of mesenchymal stromal cells?
* self renewal
* lineage commitment and differentiation
79
what are the properties of hematopoietic stem cells?
* self-renewal
* lineage commitment and differentiation\
* prevention of oncogenesis
* Can give rise to all blood cells
* They are present in several locations in your body, including your bone marrow
80
what are the properties of muscle stem cells?
* self renewal
* quiescence and activation
81
what are the properties of epithelial stem cells?
Staining showing stem cells sparse in the germinative (bottom) layer of the epidermis,progressively growing into the layers above to regenerate the whole thickness of your epidermis.
82
what does pathogenic mean and what percentage of disease causing organisms are pathogenic?
* There are many millions of bacteria, fungi and viruses but relatively few are pathogenic
* Pathogenic - a disease causing organism
* ie relatively few can evade the immune system and cause disease
* Mostly our immune system reacts so quickly we are not aware of the attack
83
list some common pathogens?
Bacteria Viruses Fungi Parasite and sometimes Cancer
84
how does the body detect pathogens?
* Immune cells stationed to detect microbial invasion are equipped with Pattern Recognition Receptors (PRR)
* These cells are part of the rapid response -the innate immune system
* They recognize Pathogen Associated Molecular Patterns (PAMPS)
85
what are PAMPs?
* PAMPs are characteristic of common microbes– Bacterial and fungal cell wall components– Viral and bacterial RNA and DNA
86
what are some examples of PRR?
* Innate immune cells with PRR include– Phagocytes such as neutrophils and macrophages– Dendritic cells
87
what are phagocytes?
cells that can undergo phagocytosis
88
what are neutrophils
* Neutrophils are also important phagocytes
* Largest circulating white blood cell population
* Bone marrow produces trillions each day
* First line of defence against invading microbial pathogens
* They phagocytose pathogens (phagocytosis) and have other killing mechanisms
* They die within 1-2 days
* Pus = dead neutrophils and dead pathogen
89
what are the Neutrophil killing mechanisms?
* phagocytosis
* degranulation
* NET (Neutrophil Extracellular trap)
90
how do Eosinophils kill pathogens and why is this useful?
Eosinophils kill pathogens by exocytosis
Externalisation of lysosomal vesicles containing toxic proteins and enzymes to destroy larger parasitic organisms e.g. Helminth worms Exocytosis
Particularly effective for combating larger organisms
91
what are the limitations of the innate immune system and how can the adaptive immune system make up for these limitations?
* Innate immune system is rapid and canbe effective but...
– Only 1000 patterns recognized
– No memory
* Adaptive immune system
– Can adapt to protect against a specific invader (100 million ‘antigens’ recognized)
– has memory
– but needs time to prepare
92
what are the 2 cells of the adaptive immune system?
Cells of the Adaptive Immune System are B and T lymphocytes
93
how do B cells work?
* 100 million B cells each able to create a different antibody recognizing a different antigen Antibody
* As B cell develops it chooses at random from many possible gene segments for heavy chain and light chain. As they are joined extra DNA bases added or deleted at the junctions
* T cells use a similar method to create their antigen receptors
94
what do T and B lymphocytes detect?
B lymphocytes and T Lymphocytes recognize an almost limitless array of structures (antigens)
95
do antibodies kill pathogens?
Antibodies do not kill the organism directly. They bind to the organism and lead to it’s destruction by other cells of the immune system.
96
when are memory B cells created and what do they do?
Memory B cells created after the first response recognize the same pathogen and respond much more rapidly and strongly*
97
how do T cells work?
T cells respond to antigen presented by an Antigen–presenting cell.This is often a dendritic cell.The T cells become effector T cells including T helper cells
98
what are effector T cells?
* Helper T cells produce different types of mediator (cytokine) to suit the threat
* Cytotoxic T cells can kill virus infected cells or tumour cells
99
what are cytokines?
* Communication mechanism forcells of the immune system
* Secreted mediators which act locally or at a distance
* Secreted by many cell types especially cells of the immune system to stimulate and shape immune responses
* Secreted in response to microbes or other cytokines
* Powerful molecules – act at nanomolar levels
100
how do cytokines work?
Cytokines act on blood vessels to help the recruitment of more immune cells to the tissue
Cytokines act on the recruited immune cells to activate them more
examples of cytokines: TNF, IL-1 and IL-6are powerful cytokines generated by the innate immune response.They can have local effects
Cytokines such as TNF, IL-1 and IL-6 can also have systemic effects.With too much cytokine the systemic effects can be harmful and possibly dangerous
101
what is septic shock?
* Septic shock is a severe and frequently fatal form of sepsis (severe infection which enters the bloodstream)
* Characterised by– collapse of blood vessels– widespread blood clotting– metabolic disturbance– can lead to multiple organ failure
* For example due to LPS induced PRR signalling in innate cells– production of TNF, IL-1 and other cytokines (cytokine storm)
102
how do allergies work?
* Some innate cells designed to respond rapidly to infection are triggered by allergen to release their mediators
* For example– histamine which causes sneezing and itching
103
what is an autoimmune disease?
Immune system targets self antigens in genetically susceptible individuals
104
what is immunodeficiency?
Many people suffer from Immunodeficiency– Due to mutation in genes coding for major components of the immune system (primary immunodeficiency)
* Eg Severe Combined Immunodeficiency (SCID) where T and B cells defective
– Due to age, malnutrition, drugs, AIDS (secondary immunodeficiency
)* Depending on how severe this can result in repeated infection and premature death
105
How can the immune system cause damage, and what mechanisms are in place to prevent autoimmunity?
The immune system can cause damage if it responds to its own tissue not just to foreign antigen
Damaging autoreactive immune responses must be prevented
– Autoreactive lymphocytes eliminated as they develop
– No responses unless accompanied by a ‘danger signal
– Regulatory cells can suppress an autoreactive response
106
what is passive immunity?
Transfer of antibodies from immune individual
107
what are the advantages and disadvantages of passive immunity?
* Advantages:
- Gives immediate protection - > A quick fix
* Disadvantages
- Short term effect – > no immunological memory
-Serum sickness – > incoming antibody is recognised as a foreign antigen by the recipient
108
what is an example of natural passive immunity?
Maternal antibody transferred to foetus across placenta
109
what is an example of artificial passive immunity?
* Snake or spider bites, scorpion or fish stings
- passive infusion of antibody specific for the toxin
* Ebola
- Antiserum from survivors
* Primary or secondary deficiency in antibody
- infusion of antibody to reduce infection
* Rabies Antibody
-“Post-exposure prophylaxis” together with vaccination
110
what is vaccination?
* Vaccination is the administration of antigenic material (a vaccine) to stimulate an individual's immune system to develop adaptive immunity to a pathogen.
– Long-term
– Faster and better response next time
111
what are the two types of conventional vaccines? describe them.
* Killed whole organism
- Target organism, e.g., polio virus is killed*Very effective and relatively easy to manufacture*Virus must be heat killed effectively
– any live virus can result in vaccine-related disease
* Attenuated whole organism
- An avirulent strain of target organism is isolated
- Can be very powerful and even better than killed
- Possibility of reversion back to virulent form– so safety?
112
what are the types of vaccines?
* live attenuated
* inactivated (killed antigens)
* toxoids (inactivated toxins)
* subunit (purified antigens)
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what are some examples of a live attenuated vaccine?
* Tuberculosis (BCG)
* Oral polio vaccine
* Measles (MMR)
* Yellow fever
* Varicella zoster
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what are the qualities of inactivated vaccines?
* Whole-cell pertussis
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what are some examples of toxoid vaccines?
* Tetanus Toxoid
* Diphtheria toxoid
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what are the qualities and examples of subunit vaccines?
* Acellular pertussis
* Pneumococcal
* Hepatitis B
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please give a brief description on the history of vaccinations?
* First vaccine was made against smallpox(Variola virus)
* Last known natura lcase in Somalia 1977.
* Small lab accident in 1978 in Birmingham –killed one person and small outbreak.
* Smallpox was officially declared eradicated in 1980.
* Polio close to eradication
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what are some commonly vaccinated against diseases? give a brief description on these diseases
* Measles one of most contagious viral diseases. Most unpleasant and the most dangerous of the children's diseases that result in a rash.
* Mumps also caused by a virus and can lead to meningitis and infertility.
* Rubella is dangerous to unborn children.
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what is the HPV vaccine and what does it do?
* Cervical cancer 2nd most common cause of cancer death in females
* HPV is linked to 100% of all cervical cancers
* Vaccine complete protection against >70% of cancer-causing HPV strains
* Currently 2 vaccines are now available
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how effective is the HPV vaccine?
* Vaccine sees huge drop in early cancer signs 03 October 2017
* The number of young Scottish women showing early signs of potential cervical cancer have almost halved since the introduction of a school vaccination programme in 2008
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why are monoclonal antibodies useful?
* New more specific and effective treatments for many diseases eg cancer, autoimmune diseases
* Diagnostic kits eg for infectious diseases, malignancy,pregnancy testing
* New opportunities for research
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What is the function of B cell hybridomas in the production of monoclonal antibodies?
B cell hybridomas are immortalized cells used to produce multiple copies of a single antibody with a unique specificity. This ensures the continuous production of identical antibodies.
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What is the general process for generating monoclonal antibodies using hybridoma technology? (mouse antibodies)
The process involves immunizing a mouse, isolating B-cells, fusing them with myeloma cells to form hybridomas, selecting them in HAT medium, and then screening for the desired monoclonal antibodies.
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why are mouse antibodies problematic?
mouse antibodies may be recognized by humans as foreign
– Humanised antibodies needed
– Made in mice engineered to give human antibody
– Mice reported to cost over a million dollars
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what are some examples of monoclonal antibody studies?
* Humira (adalimumab)
– anti-TNF
– Rheumatoid arthritis* Herceptin (trastuzumab)
- blocks human epidermal growth factor receptor (HER2)
- effective in HER2 positive metastatic breast cancer
* Avastin (bevacizumab)
– anti-VEGF
– inhibits angiogenesis in age
–related macular degeneration eye disease
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What are the components of the first HER2-targeted Antibody-Drug Conjugate (ADC), KADCYLA? (antibodies in targeted drug delivery)
KADCYLA consists of three main components:
1) Trastuzumab, a monoclonal antibody that targets the HER2 receptor;
2) DM1, a cytotoxic agent (maytansinoid) that kills cancer cells; and
3) MCC, a stable linker that connects the monoclonal antibody to the cytotoxic drug.
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what are checkpoint inhibitors?
* New exciting, powerful anti-cancer drugs
* Checkpoint inhibitor antibodies unlock the gateway to the adaptive immune system by targeting an inhibitory molecule eg CTLA-4
* But potential for immune related adverse effects
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what are Bispecific antibodies?
* Recombinant technology can now be used to re-configure antibodies to bind more than a single target
* Useful therapies
* Typically, one of the targets immune-related to boost the immune system
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what are the steps involved for Tumour immunotherapy with T cells
* T cells are isolated from patient
*Cultured so that they proliferate
*Genetically modified so that they have a receptor specific for a tumour antigen and with the ability to promote strong T cell activation
*Transferred back to patient
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how can peptides be used in desensitization therapy?
* Companies are working on finding peptides which can be used to desensitise allergic patients eg ToleroMune® for cat dander allergy
* Other targeted allergies include house dust mite and grass pollen
* The peptides induce immune regulatory cells which dampen down the immune system
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what is cell theory?
* The idea that there is a basic unit of structure for every living thing
* (1665) Robert Hooke was the first to identify cells in very thin slices of cork
* Hooke’s observations were of cell walls and not the living cells
* These observations therefore didn’t provide evidence of cellular components and organelles
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who was Anton van Leeuwenhoek and what did he do?
* (1674) Anton van Leeuwenhoek was the first person to view living cells under a microscope
* He called them animalcules(meaning little animals)
* He was also the first person to identify the nucleus
* He called it a lumen, meaning cavity
* Used salmon red blood cells
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what is the history of the nucleus and what did Matthew Schleiden believe about it?
Initially the nucleus was simply described as a structure within the cell
* In 1838, Matthias Schleiden (a botanist) believed the nucleus (or cytoblast as he called it) played apart in generating new cells
* Cytoblast means “cell builder”
* He believed that new cells “blistered” off of the nucleus to develop into new cells
* He was the first person to make the link, allbe it incorrectly, with the nucleus and cell division
* This was based on him using microscopy to see clusters of new cells growing from plant cells
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what did Oscar Hertwig believe about the function of the nucleus (unit of heredity)
* Oscar Hertwig identified the sperm cells of many organisms transferred their nuclei to the oocyte
* Before these discoveries it was believed that a tiny human (a homunculus) was contained within the sperm, which would then be transferred to the mother
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who discovered DNA?
Friedrich Miescher
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What did Friedrich Miescher initially intend to study, and what did he discover?
Miescher initially wanted to identify proteins from leukocyte cells. While doing so, he extracted proteins from pus samples and discovered several proteins in the leukocytes.
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What was Friedrich Miescher’s approach to studying the nucleus?
Miescher was the first person to extract cell nuclei. He identified that the substance within the nucleus had different chemical properties than known proteins at the time, and further tests showed it was present in many different cell types.
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What was unique about the substance Friedrich Miescher extracted from the nucleus?
Miescher found that the substance, which he termed 'nuclein', had uniform chemical properties across various cell types, unlike proteins which varied. Nuclein was later understood to be DNA.
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Who discovered the staining technique for DNA, and what was the dye used?
In 1914, Robert Feulgen discovered that fuchsin dye could be used to stain DNA, which helped in identifying DNA in cells under a microscope
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After the development of the DNA staining technique, what was revealed about the presence of DNA in cells?
Following Robert Feulgen's discovery, it was established that DNA is found in ALL cells, including both eukaryotic and prokaryotic cells.
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what did Frederick Griffiths discover?
Griffith was an English microbiologist* (1928) Griffith identified that there was a“transforming” factor that could make non-virulent Streptococcus pneumoniae cellsvirulent
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what did Phoebus Levene discover in terms of structure?
(1919) Russian biochemist Phoebus Levene was the first to understand the components of the DNA molecule
* At this time nobody knew what DNA was really made from
* Levene spent many years working out that DNA was made from nucleic acids that consisted of nitrogen containing bases, a sugar molecule and a phosphate molecule
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What did Frederick Griffith discover about the transformation of bacteria?
Griffith demonstrated that a "transforming factor" could make non-virulent cells become virulent, indicating that this factor was key to the inheritance of virulence.
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Who identified DNA as the "transforming" factor and how?
Oswald Avery and his team, through a process of elimination, identified DNA as the "transforming" factor. They deduced this without using animal experiments, instead observing the change in cell appearance to confirm DNA's role.
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How did Avery's team confirm the role of DNA in transformation?
Avery's team observed that DNA could transform a non-virulent strain of bacteria to become virulent by noting the changes in the cells' appearance from small (non-virulent) to large (virulent).
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What was Levene's hypothesis about the structure of nucleotides, and how was it disproven?
Levene believed that nucleotides were arranged in a fixed, repetitive sequence. This was disproven by Erwin Chargaff in 1950, who found that different organisms have different proportions of nucleotides.
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What is Chargaff's rule?
Chargaff's rule states that DNA always has equal amounts of adenine (A) and thymine (T), and guanine (G) and cytosine (C), across all organisms. Chargaff was unable to determine why these nucleotides were always in equal proportion to each other.
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Who conducted X-ray diffraction experiments on DNA crystals and what did they discover?
In 1953, Rosalind Franklin and Raymond Gosling conducted X-ray diffraction experiments on DNA crystals. They identified two distinct forms of DNA, known as A and B forms, both of which suggested a helical structure.
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When did the term "molecular biology" come into existence, and what has been its academic evolution?
The term "molecular biology" did not exist before 1938. Now, it is a well-established field, and degrees in molecular biology are offered at almost any university you can think of.
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How was genetics practiced before the understanding of genes and DNA?
Long before the concepts of genes or DNA were understood, genetics was practiced through selective breeding. People crossed animals and crops to develop desired traits, with records of such practices dating back over 5,000 years.
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What assumptions did early plant breeders work on regarding heredity and what does this tell us about genetics?
Early plant breeders worked on two assumptions: that each parent contributes equally to their offspring and that heritable traits blend in the offspring. However, only the first assumption was supported by experiments. This tells us that genetics was practiced in the past.
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Who was Gregor Mendel, and what was his contribution to the field of heredity?
Gregor Mendel was an Austrian monk who, through extensive gardening, conducted hundreds of plant crosses over 8 years and described over 24,000 progeny. His meticulous work in the 1860s led him to formulate the fundamental laws of heredity, laying the groundwork for the field of genetics.
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What did Mendel's experiments with plant height in pea plants reveal about heredity?
Mendel's pea plant experiments established that traits are determined by hereditary units, now known as genes, with individuals inheriting two copies—one from each parent. His work showed a 3:1 ratio of tall to short plants in the second generation, leading to the discovery of dominant and recessive traits. These findings refuted the blending theory of inheritance, proving instead that genes retain their distinct identity through generations.
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Who coined the term "gene" and who demonstrated the chromosomal basis of heredity?
Wilhelm Johannsen, a Danish botanist, was the first to use the term "gene" in 1909. Thomas Hunt Morgan, through his work with fruit flies showing red and white eye color inheritance, demonstrated that genes are located on chromosomes, paralleling Mendel's pea plant inheritance patterns. Morgan's findings earned him the Nobel Prize in Medicine in 1933.
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What are the key milestones in the development of molecular biology from the 1940s to the 1960s?
In 1940, the connection between genes and proteins was established.
By 1944, DNA was recognized as the material of genes (Oswald Avery).
In 1952, DNA's role in viral heredity was confirmed. Watson and Crick's model of DNA came in 1953.
The discovery of mRNA occurred in 1961, and between 1961-1965, the process from DNA to RNA to protein was elucidated, along with the discovery of DNA-binding proteins that regulate gene expression. These discoveries underpin molecular biology's framework.
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How has the concept of a hereditary unit within a living cell evolved since it was first discussed by Gregor Mendel in the 1860s?
Initially conceptualized by Mendel, a hereditary unit, now known as a gene, is understood as a defined segment of DNA sequence that codes for an mRNA. A gene includes specific start and stop positions on the extensive genomic DNA sequence, directing the synthesis of proteins through mRNA intermediates.
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What is "The central dogma" of molecular biology as coined by Francis Crick in 1958?
The central dogma, introduced by Francis Crick, describes the one-way flow of genetic information: from DNA to RNA to protein. It asserts that information transfer is sequential and unidirectional, stating specifically that information cannot be transferred back from protein to either protein or nucleic acid.
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What are the various types of proteins produced by gene expression and their associated functions or links to diseases?
Gene expression, typically leading to protein production, can result in structural proteins like collagen and elastin; signaling proteins such as insulin and neurotransmitters; enzymes like amylase and trypsin; transcription factors including PDX-1, associated with diabetes (MODY); and STAT proteins, linked with breast cancer. Gene activation is a complex process influenced by multiple factors, driving the diversity of protein functions in biological systems.
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what is the function of gene expression?
to make proteins
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what are the different categories of proteins?
* structural proteins
* signalling proteins
* enzymes
* transcription factors
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who discovered that genes make proteins?
Archibald Garrod, linked genes to protein production. Observing children with alkaptonuria, characterized by dark urine, he connected inherited traits to their condition after Mendel's genetics work was rediscovered. Garrod identified homogentistic acid in these children's joints and, with the recent discovery of enzymes, suggested an enzyme's role in its accumulation. This led to his "one gene, one enzyme" hypothesis. The gene mutation responsible was identified in 1996.
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how did George Beadle and Edward Tatum expand on Archibald Garrods work?
George Beadle and Edward Tatum used X-ray radiation to mutate the DNA of Neurospora mold. They identified specific Neurospora strains with distinct characteristics. Many strains required additional nutrients to grow. Their research uncovered genes affecting the metabolism of specific amino acids, like arginine, essential for the mold's growth.
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explain the process of George Beadle and Edward Tatums mold experiment?
* Wild type grows on all media
* Mutant strain 1 only grows on arginine media
* Mutant strain 2 can grow on either arginine or citrulline media, but not on ornithine media
* Mutant strain 3 can grow when anyof the three supplements are added,but not in media with no supplements
* They had shown for the first time that each mutant strain was deficient in one enzyme in a biological pathway
* They repeated this for many more proteins
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what currently dont we know about DNA?
* How genes are switched on* How genes contribute to diseases* How genes relate to medicine
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how is eukaryotic gene expression regulated?
* Must be regulated to ensure proper timing and location of protein production
* Regulation can occur at multiple points in transcription and translation
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what are the potential points for the regulation of Gene Expression?
* remodelling of chromatin
* transcriptional control
* processing control
* transport control
* mRNA stability control
* translational control of protein synthesis
* posttranslational control of protein activity
* protein degradation
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what are transcription factors and what are the two important sequences?
* Transcription factors act at eukaryotic promoters regions of DNA where RNA polymerase binds and initiates transcription
* Two important sequences:
- Recognition sequence—recognized by RNA polymerase
- TATA box—where DNA begins to denature and expose the template strand
* Some sequences are common to promoters of many genes; recognized by transcription factors in all cells
* Some sequences are specific to a few genes and are recognized by transcription factors found only in certain tissues (or cells)
* These play an important role in differentiation
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besides the promoter what are other sequences that bind to regulatory proteins that interact with RNA polymerase and regulate rates of transcription?
* Some are positive regulators
- enhancers
* Others are negative
- repressors
* The combination of factors present determines the rate of transcription
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what are the three criteria for DNA recognition by a protein
Three criteria for DNA recognition by a protein motif:
* Fits into major or minor groove
* Has amino acids that can project into interior of double helix
* Has amino acids that can bond with interior bases
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what are genetic mutations?
Genetic mutations are changes in the nucleotide sequences of DNA that are passed on to the next generation
Mutations may or may not have a phenotypic effect
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what are the two types of mutations?
Somatic mutations occur in somatic (body) cells—passed on by mitosis but not to sexually produced offspring
Germ line mutations—occur in germ line cells, the cells that give rise to gametes. A gamete passes a mutation on at fertilization
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what are the two types of mutations that exist in the molecular level?
A point mutation—results from the gain, loss, or substitution of a single nucleotide
Chromosomal mutations are more extensive—may change the position or cause a DNA segment to be duplicated or lost
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how do genetic mutations normally manifest?
Genetic mutations often manifest themselves as abnormal proteins
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what is phenylketonuria (PKU)
First described in 1934
Phenylpyruvic acid builds up in the urine
Mental retardation occurs
Light skin and hair colour
the molecular cause was known to be a dysfunctional enzyme
(Phenylalanine hydroxylase)
Only recently has the exact genetic mutation been discovered, which causes one of the 452 amino acids that make up this enzyme to change
This is an example of a single genetic change that can affect a single protein to cause disease
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how are genetic diseases usually treated?
Most treatments currently available will try to alleviate the symptoms of the disease
More recently scientists have been looking at alternatives to this approach
Modifying the disease phenotype
Replacing the defective gene
This requires a thorough understanding of the molecular basis of the disease in question
Some of these ideas are also highly controversial
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give examples of ways genetic diseases can be treated?
* restricting substance - less substance = less symptoms
* adding a metabolic inhibitor - An enzyme inhibitor blocks the harmful effects of the built up substrate
* restoring missing enzyme - Addition of wild type protein substitutes for the mutant enzyme. a protein isn’t working properly so we replace it with a functional version
- This is easier said than done, but has been a success in several instances:
Insulin
Blood factor VIII
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how can restricting substance technique work in treating PKU?
This is the method of treatment if you suffer from PKU
A baby born with PKU will be put on a low phenylalanine diet, as this is the substrate that then produces the dangerous levels of phenyl pyruvic acid
Meat, fish, eggs and dairy products must be avoided, particularly in childhood while the brain is developing
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how can we use metabolic inhibitors to treat depression?
Most drugs act as inhibitors to specific enzymes or signalling molecules
For example, anti-depressants are often inhibitors of neurotransmitters in the brain
Many new drugs are found by screening thousands of compounds to see which can act as inhibitors
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what is the purpose of gene therapy?
In gene therapy, the aim is to supply the missing gene(s) by inserting a new gene that will be switched on in the host cells
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what are the challenges that may be faced when using gene therapy?
Must find appropriate vector
Ensure precise insertion into host DNA
Ensure appropriate expression
Select cells to target
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why are ex vivo techniques useful in gene therapy?
The nonfunctional genes cannot be replaced in every cell of the body
Ex vivo techniques—cells are removed from the body, new genes inserted in the laboratory, cells returned to the body so that correct gene products are made
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what is SCID?
immunodeficiency diseases may result from single-gene mutations. The IL2RG protein, essential for white blood cell maturation, when lacking, causes severe combined immunodeficiency (SCID), famously known as "bubble boy" disease. This term gained prominence from David Vetter's highly publicized case in the 1970s. Vetter, with SCID, lived in a plastic bubble from birth until age 13. He ultimately died due to a viral infection contracted from a bone marrow transplant.
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how can SCID be cured and if so, is there any side effects of treatment used to cure SCID?
Using a virus, a “normal” version of the IL2RG gene is inserted into the genome of SCID sufferers
It has worked in many cases, but recently several children have developed leukaemia as a consequence of the treatment
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how does gene therapy in vivo work?
genes inserted directly into body cells
Example: DNA can be introduced into the lungs as an aerosol to treat lung cancer
Hopefully the DNA will be incorporated into the patient’s genome, and the disease will improve or disappear
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what are the steps to sequence an entire human genome?
To sequence the human genome, DNA is fragmented into 500 base pair lengths, akin to cutting a 1 km string into 0.0015 mm pieces. With approximately 3.3 billion base pairs, this creates 6.6 million fragments. These are then reassembled using overlapping larger fragments known as contigs
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what is bioinfomatics?
The field of bioinformatics was developed to analyze DNA sequences using complex mathematics and computer programs
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how did the human genome project sequence a genome?
The Human Genome Project used two approaches:
* Hierarchical sequencing
- Overlapping parts of the sequences are aligned (with the aid of computers) to create larger sequences
- Then the larger fragments are arranged in sequence to produce a chromosome map
* Shotgun sequencing
- This method cuts DNA into smaller, overlapping fragments that are sequenced
- Computers are used to search for overlapping markers
This approach is much faster and cheaper
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what are universal genes?
Certain genes are present in all organisms (universal genes); and some universal gene segments are present in many organisms
This suggests that a minimal set of DNA sequences is common to all cells
M. genitalium can survive in the laboratory with only 382 functional genes
Efforts are underway to make a synthetic genome based on M. genitalium – to create artificial life
This could have many useful benefits, but also many ethical concerns
