Much as I hate to admit it, many superstitions are grounded in fact. Take the swollen feet one, for instance. We are told to soak swollen feet in warm salty water, the theory being that the swelling would reduce.
Here’s the scientific bit:
Water moves from an area of high concentration to an area of low concentration. An accumulation of fluid can be one reason for swelling to occur. Soaking your feet in water would cause would cause the water to move out from your feet into the warm salt water. We all know that heat would enhance the process.
The question remains:
How hot should the water be?
How much salt should be added to the warm water?
How long should you soak your feet for the procedure to be successful?
I have visions of prune like toes and other wriggly bits…….
Wednesday, April 28, 2010
Phagocytosis (effector functions of Ab)
When phagocytosis takes place, the cell membrane of the phagocyte adheres to the cell membrane of the Ag. There are many Ag that possess structures that interfere with this adherence. Examples of these structures are capsules. In this case, the immune system compensates. It does this by forming Ab, activating complement and using cell receptors. How does it do this? Lets begin
Firstly the immune system produces a specific Ab to the Ag. This becomes an immune complex. If the Ab is either IgG or IgM, the immune complex is capable of activating complement. Remember that C’ attaches to CH2 of IgG and CH3 of IgM. When C’ is activated, the cascade results in the formation of C3b which attaches to the cell membrane of the Ag and acts as a cell receptor or cell marker. This receptor interacts with CR1 and CR3 both of which are expressed by phagocytes. Round one to the immune system.
Secondly the Fc portion of the Ab can nad does interact with phagocytes via the Fc gamma receptor found on the phagocyte. Round two to the immune system.
Remember at the beginning the Ag was all excited because it had this capsule. It was jumping all around saying; ‘ha ha ha, I have a capsule and you can’t phagocytose me!’ now its game set and match in favour of the immune system. Immune system saves the day yet again!
Firstly the immune system produces a specific Ab to the Ag. This becomes an immune complex. If the Ab is either IgG or IgM, the immune complex is capable of activating complement. Remember that C’ attaches to CH2 of IgG and CH3 of IgM. When C’ is activated, the cascade results in the formation of C3b which attaches to the cell membrane of the Ag and acts as a cell receptor or cell marker. This receptor interacts with CR1 and CR3 both of which are expressed by phagocytes. Round one to the immune system.
Secondly the Fc portion of the Ab can nad does interact with phagocytes via the Fc gamma receptor found on the phagocyte. Round two to the immune system.
Remember at the beginning the Ag was all excited because it had this capsule. It was jumping all around saying; ‘ha ha ha, I have a capsule and you can’t phagocytose me!’ now its game set and match in favour of the immune system. Immune system saves the day yet again!
Effector functions of Antibodies
The principal reason for antibodies being produced is for agglutination. When the Ab combines with the Ag, it forms an immune complex. If the Ab is either IgG or IgM, the immune complex is capable of activating complement and results in lysis of the antigen.
However Ab serve many more functions. These are the effector functions referred to in the title. The Fc portion of the Ab can attach to many cells, and bring about a specific function. The function depends on the cell it attaches to. Some of the cells that can attach to the Fc portion are neutrophils, macrophages, monocytes and trophoblasts.
Not all Ab attach to these cells. The attachment is not really so. It is more an interaction via Fc receptors. These receptors are found on the surface of cells. The Ab that interact with Fc recptors are IgG, IgM, IgE. The Fc receptor is named according to the type of Ab it interacts with. It is Fc epsilon if it interacts with IgE, Fc gamma for IgG and Fc mu for IgM.
IgA is found in the various parts of the body where mucous is secreted. Many Ag enter the body here. The Ab interferes with colonization of the Ag and therefore reduces or stops infection taking place. The Ab also reduces the infectivity of viruses.
A toxin is produced by certain bacteria once they have entered the body. The toxin is harmful and can affect the body in many ways. The immune response is to both the Ag and the toxin. Ab produced in response to the toxin are specific to the toxin. Now the toxin exerts its effect by combining with man’s tissues/cells. The actual part that comes into contact with man’s tissues is called the active site. The immune system must somehow stop the active site from coming into contact with tissue. So the Ab does this in either one of two ways. Firstly the Ab will combine with the toxin near or actually at the active site. This effectively blocks the active site. Secondly the Ab combines far from the active site, thereby causing a change in the morphology or structure of the active site. In both instances, the active site is unable to carry out its function. A point to note here is that this is an example of active natural immunity. In the case of administration of antitoxin, it is passive artificial immunity.
I will deal with immune system compensation for non adherence to phagocyte in another blog entry
However Ab serve many more functions. These are the effector functions referred to in the title. The Fc portion of the Ab can attach to many cells, and bring about a specific function. The function depends on the cell it attaches to. Some of the cells that can attach to the Fc portion are neutrophils, macrophages, monocytes and trophoblasts.
Not all Ab attach to these cells. The attachment is not really so. It is more an interaction via Fc receptors. These receptors are found on the surface of cells. The Ab that interact with Fc recptors are IgG, IgM, IgE. The Fc receptor is named according to the type of Ab it interacts with. It is Fc epsilon if it interacts with IgE, Fc gamma for IgG and Fc mu for IgM.
IgA is found in the various parts of the body where mucous is secreted. Many Ag enter the body here. The Ab interferes with colonization of the Ag and therefore reduces or stops infection taking place. The Ab also reduces the infectivity of viruses.
A toxin is produced by certain bacteria once they have entered the body. The toxin is harmful and can affect the body in many ways. The immune response is to both the Ag and the toxin. Ab produced in response to the toxin are specific to the toxin. Now the toxin exerts its effect by combining with man’s tissues/cells. The actual part that comes into contact with man’s tissues is called the active site. The immune system must somehow stop the active site from coming into contact with tissue. So the Ab does this in either one of two ways. Firstly the Ab will combine with the toxin near or actually at the active site. This effectively blocks the active site. Secondly the Ab combines far from the active site, thereby causing a change in the morphology or structure of the active site. In both instances, the active site is unable to carry out its function. A point to note here is that this is an example of active natural immunity. In the case of administration of antitoxin, it is passive artificial immunity.
I will deal with immune system compensation for non adherence to phagocyte in another blog entry
Wednesday, April 7, 2010
To think about....
Why would you recommend to a friend that he places 5, 10 and 20 cent
coins in his pet’s water bowl?
Why can someone get very ill from eating a lot of cold meats all at once?
Why is silver nitrate put into the eyes of newborns?
coins in his pet’s water bowl?
Why can someone get very ill from eating a lot of cold meats all at once?
Why is silver nitrate put into the eyes of newborns?
TRANSMISSION OF DISEASE
Categorised as either vehicle, vector and contact
Vehicle is non living
Vector is living
Contact is you know???
Mechanical vehicle is the insect itself ex allergy to bee sting
Biological vehicle is when part of life cycle of pathogen is inside insect ex malaria
Example of Waterborne vector is cholera
For pathogens to be transmitted though air, the distance must be less than 1 meter
Foodborne pathogen transmitted through cooking utensils, food itself, etc
Direct contact is kissing, sex
Indirect contact is through fomites
Droplets are when nasty people sneeze and cough directly on you
Vehicle is non living
Vector is living
Contact is you know???
Mechanical vehicle is the insect itself ex allergy to bee sting
Biological vehicle is when part of life cycle of pathogen is inside insect ex malaria
Example of Waterborne vector is cholera
For pathogens to be transmitted though air, the distance must be less than 1 meter
Foodborne pathogen transmitted through cooking utensils, food itself, etc
Direct contact is kissing, sex
Indirect contact is through fomites
Droplets are when nasty people sneeze and cough directly on you
Media tut questions
Choose the odd one out, and justify your choice
1. Peptone, asparagines, L cysteine, glucose
2. Malachite green, glycerol, asparagines, methylene blue
3. Ferric citrate, magnesium citrate, ferric ammonium citrate
4. Increased dextrose, Proteus, decrease Ph, Rhizopus
5. Rabbit blood, trimethoprim, penicillin, Bordet Gengou
6. Sterile mineral oil, closed, Pseudomonas, fermentative
7. Trimethoprim, vancomycin, nystatin, colistin
8. Ox bile, brilliant green, K tellurite, blood
9. Bile salts, ox bile, sodium citrate
10. Black colour in oxidase, acid slant in TSI, red layer at top of SIM, negative citrate
11. E coli, Klebsiella, Proteus, Salmonella
12. Bacillus, Staphylococcus, Neisseria, E coli, Klebsiella
13. Pseudomonas, E coli, Alcaligenes, Streptococcus
14. 40%KOH, alpha naphthol, MRVP, p dimethylaminobenzaldehyde, methyl red reagent
15. Pink urease, low electrolytes, PAD pos, alkaline slant
1. Peptone, asparagines, L cysteine, glucose
2. Malachite green, glycerol, asparagines, methylene blue
3. Ferric citrate, magnesium citrate, ferric ammonium citrate
4. Increased dextrose, Proteus, decrease Ph, Rhizopus
5. Rabbit blood, trimethoprim, penicillin, Bordet Gengou
6. Sterile mineral oil, closed, Pseudomonas, fermentative
7. Trimethoprim, vancomycin, nystatin, colistin
8. Ox bile, brilliant green, K tellurite, blood
9. Bile salts, ox bile, sodium citrate
10. Black colour in oxidase, acid slant in TSI, red layer at top of SIM, negative citrate
11. E coli, Klebsiella, Proteus, Salmonella
12. Bacillus, Staphylococcus, Neisseria, E coli, Klebsiella
13. Pseudomonas, E coli, Alcaligenes, Streptococcus
14. 40%KOH, alpha naphthol, MRVP, p dimethylaminobenzaldehyde, methyl red reagent
15. Pink urease, low electrolytes, PAD pos, alkaline slant
MEDIA Tuts
Explain the relationship between:
Methyl red reagent; MRVP; acidic end products; pH6; Enterobacter aerogenes
Voges Proskauer; MRVP; non acidic end products; pH4; Escherichia coli
YOU NEED TO KNOW:
MRVP is the medium. It comprises 2 tests, MR and VP.
Both tests are used to differentiate between E coli and Enterobacter aerogenes.
Both orgs degrade glucose and form by products (E coli at pH4, and Ent at pH6)
Mr tests for pH4 and VP tests for pH6. In both tests a red colour is positive.
E coli end products are called acidic
Ent end products are called non acidic.
Therefore E coli is MR pos and VP neg
Enterobacter is MR neg and VP pos
Methyl red reagent; MRVP; acidic end products; pH6; Enterobacter aerogenes
Voges Proskauer; MRVP; non acidic end products; pH4; Escherichia coli
YOU NEED TO KNOW:
MRVP is the medium. It comprises 2 tests, MR and VP.
Both tests are used to differentiate between E coli and Enterobacter aerogenes.
Both orgs degrade glucose and form by products (E coli at pH4, and Ent at pH6)
Mr tests for pH4 and VP tests for pH6. In both tests a red colour is positive.
E coli end products are called acidic
Ent end products are called non acidic.
Therefore E coli is MR pos and VP neg
Enterobacter is MR neg and VP pos
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