HIV & AIDS

Well, since it's WORLD AIDS DAY TODAY - 1 DEC 2008

Here's to it.



First of all, HIV stands for Human Immunodeficiency Virus.
AIDS stands for Acquired Immunodeficiency Syndrome.

HIV is the virus that causes the disease AIDS.


HIV attacks the body by affecting a type of white blood cell called the T lymphocyte, or T cell. T cells are cells in the immune system which help the body fight off infections and diseases.


After the HIV enters the body, it carrys onto a T cell and works its way into the cell. Once it completely takes over the T cell, it starts making many copies of itself. The newly made viruses then leave the T cell and go on to infect other healthy working T cells. After being invaded by the virus, the T cells can no longer work properly to fight infections.


However, it may take years for the virus to damage enough T cells to make a person fall sick and develop AIDS. Due to medications, people infected with HIV can stay relatively healthy and symptom-free for many years. Nevertheless, the virus is still silently reproducing itself and destroying T cells. The person is still contagious and may pass on the virus to someone else.


When most of the T cells have been destroyed by the virus leading to low T cells count, a person's immune system will weaken, and can no longer fight off infections hence showing signs of serious infection. This is when he/she is diagnosed with AIDS.



The HIV invades a white blood cell


A shoutout to sexually active people out there, protect yourself, use a condom!

How Your Body Works

Sweeties, Check this out

http://kidshealth.org/PageManager.jsp?lic=1&article_set=59296&cat_id=20607


Credits to KIDSHEATH

Let’s SHIELD our body!

Hope all of you who have visited our blog gained some knowledge about how our immune system works and enjoyed what we have shared. :D Nonetheless, here are some of the precautions that we should take note even though we might think that they are simply common sense because there are bacteria all around us and you never know whether our immune system are good enough to protect us from the more harmful organisms that can cause diseases. For instance, the Hand-foot-and-mouth disease (HFMD) that we know is common among infants and children and can be spread by direct contact. So do your part to help save our community!

§ Wash hands carefully. Be sure to wash your hands frequently and thoroughly, especially after using the toilet or changing a diaper, and before preparing food and eating. When soap and water are not available, use hand wipes or gels treated with germ-killing alcohol.

§ Disinfect common areas. Get in the habit of cleaning surfaces first with soap and water, then with a diluted solution of chlorine bleach, approximately 1/4 cup of bleach to 1 gallon of water (when necessary for the bleach part). For parents with young children, disinfecting all common areas, including shared items such as toys should be done as the virus can live on these objects for days. Also, clean your baby's pacifiers often.

§ Teach good hygiene. Be a positive role model by showing your children how to practice good hygiene and how to keep themselves clean. Explain to them why it's best not to put their fingers, hands or any other objects in their mouths.

§ Be responsible. If you are not feeling well, please visit a doctor and do not go to school or work so as not to spread the germs. Stay home and rest. Furthermore, when you are sick, your immune system is low and you will also not be able to concentrate on your work.

Alright that’s about all. Have a great day! :D

Gross Stuff! (Infections)

Wound Infections

In this post, the people from "FREAKS NOT GEEKS", would like to stress the importance of taking care of wounds regardless of the severity. Even a tiny wound has the potential to get infected and spread to become an even more severe wound. And when that happens, things are definitely gonna get ugly! So the message that we would like you to bring back is that keeping your wound clean is crucial.

Signs Of Infection

1)Pus or cloudy fluid draining from wound

2)Pimple or yellow crusts form on wound

3)Scab increases in size

4)Increasing redness around the wound

5)Wound becomes extremely tender

6)Foul odour from wound

7)Generalized chills or fever

8)Tender lumps or swelling in your armpit, groin or neck

9)Red streaks in the skin around the wound or progressing away from the wound

There you go people!

Talking care of your wound is extremely important.

We hope you've learnt a thing or two after viewing our blog.

Cheers!

References:

http://www.seattlechildrens.org/child_health_safety/health_advice/wound_infection.asp

http://www.mckinley.uiuc.edu/Handouts/wound_infection_symptoms.html

Introduction

Minor accidents such as cuts and falls are a norm to us and many times we choose to take it lightly, not bothering to treat it the correct way. However, minor cuts and falls wounds often exposes our body to all sorts of harmful bacteria as our body’s physical barrier against harmful microbes, the skin(epidermis),is broken and therefore allows for microbes outside our body to enter. When that happens, infections would occur, some minor and some severe. Fortunately, our body’s immune system has the ability to react to those harmful microbes that successfully entered our body and destroy it. However, not all the time does our body’s immune system is able to combat a certain microbe. This is when we come across severe infections and even death in certain cases. Therefore, it is crucial that we take care of our wound to prevent infections as much as possible.

Steps to Dress a Wound

Step1:Stop the bleeding

*Apply direct pressure over the wound site to stop the bleeding using a clean cloth or towel.

Step2:Clean the wound

*Rinse wound with clear water
*Remove foreign material in the wound(dirt,gravel,grass) using sterile tweezers or sterile gauze.
*Gently clean the areas around the wound with soap and water.

Step3:Apply antibacterial ointment

*Apply antibacterial ointment over the wound to prevent infection of the wound by inhibiting the growth of microbes/bacteria on the wound.

Step4:Closing the wound

*Cover the wound with a bandage or a plaster, depending on the severity of the wound, to keep it clean.
*It is good to put a fresh bandage or plaster everyday till the wound heals.

Voila! You're done!

References

http://www.ehow.com/how_2278500_treat-wound.html

http://www.find-cures.com/Treating_Wounds.html

The B cell receptor and antibodies Part 2

Antibodies

Let’s recall what antibodies are. Well, they are proteins that fight infection. Now, let’s find out what they can actually do. The functions of antibodies are merely neutralisation of viruses and toxins, complement activation and opsonisation, opsonisation and lastly antibody-dependent cell mediated cytotoxicity (ADCC).


Neutralisation - Antibodies can bind to toxin molecules or pathogens such as viruses. This prevents them from binding to receptors on the host cell and entering it.

Activation of complement – The Antibody-Antigen (Ab-Ag) complexes activate the classical pathway in which the activation of complement will lead to opsonisation of pathogens, clearance of immune complexes from the circulation, local inflammation and lysis of pathogens.


Opsonisation – The pathogens are coated with antibodies. This facilitates recognition and binding by the phagocytes. This means that the antibody will signal the phagocytes to engulf and destroy the organism or cell.

Antibody-dependent cell mediated cytotoxicity (ADCC) – Organisms that are too large to be phagocytosed are killed by toxins released by immune system cells. Cells such as Natural Killer (NK) cells, eosinophils have FcR that can bind to antibody-coated targets.

Immunoglobulin classes

There are five classes or isotypes of immunoglobulins, IgG, IgM, IgD, IgA and IgE.




There are different classes of antibodies because they carry out different functions and are directed to different parts of the body.

IgM – The first antibody that is produced in the immune response and it activates complement. It also has low affinity which means the strength of binding between the antibody and antigen is low. B cell may switch to other Ig classes later that will carry out other functions.

IgG – It is the major class of Ig in the blood and it can cross the placenta to provide passive immunity to the fetus. There are 4 subclasses of IgG. IgG 1-4 are involved in neutralisation. IgG1 is involved in opsonisation and IgG 3 is able to activate complement.

IgA – It protects mucosal surfaces (eg: respiratory tract). It is also most abundant Ig. It is found in tears, mucous, saliva, sweat and breastmilk.

IgE – It has low concentrations in serum and binds to basophils,eosinophils and mast cells through their FcR. When these cells are activated, inflammation will occur. IgE and mast cells are involved in allergic reactions.

IgD – It is found on cell membrane of naive B cells (B cells that have not encountered antigen), co-expressed with IgM. Nevertheless, its function is unknown and barely found in blood.

References

http://www.uccs.edu/~rmelamed/MicroFall2002/Chapter%2017/Antibody%20function.jpg
http://mac122.icu.ac.jp/biobk/AntiBtypes.gif

The B cell receptor and antibodies Part 1

B cell receptors


What are B cell receptors & how they come about?


As mentioned before, B cells produce antibodies. However, they do not produce those antibodies until they become fully activated. Each and every B cells has a unique receptor protein called the B cell receptor (BCR) on its surface that will specifically bind to antigen molecules. The BCR is also known as immunoglobulin (Ig) and it differentiates B cells from other types of lymphocytes as well as being the main protein involved in B cell activation. B cell receptors may be bound to the B cell membrane known as surface immunoglobulins or secreted as antibodies (Ab). The secreted antibodies carry out humoral immunity.




When the B cell receptor binds to antigen, it initiates a signal through two proteins (Ig-alpha and Ig-beta) non-covalently in the B cell receptor complex. The signal initiated by binding of antigen to the B cell receptor complex causes growth and proliferation of the B cell. This will then lead to the creation of an amplified clone of effector cells that secrete the antigen-specific immunoglobulin. In addition, activating the B cell receptor by antigen will also result in the production of memory cells that persist in circulation to produce a more rapid immune response after future challenges by the same antigen.
In case all of you are wondering how does a B cell receptor looks like.

Here is the structure.




• 4 polypeptide chains

• 2 identical heavy (H) chains and 2 identical light (L) chains


• The polypeptide chains are joined together by interchain disulfide bonds.





References

http://www.biocarta.com/pathfiles/h_bcrmolecule.asp
http://www.newworldencyclopedia.org/entry/B_cell
http://people.rit.edu/gtfsbi/imm/parhamimages.htm/Chapter%2002/figure%2002-23.jpg
http://www.immunecentral.com/immune-system/iss15.cfm

Allergies

Your body produces antibodies to help your fight off bateria, viruses and other microbes that can make you sick. When you have an allergy, it means your immune system mistaken something harmless as harmful, hence making antibodies to fight it off.

People can have allergy towards medicine (e.g. penicillin), pollen, food, etc.


Penicillin allergy

Let's see what happens during a food allergy.

When someone is allergic to peanut, and has eaten a peanut butter jelly sandwich, this is what will happen. Antibodies against something in the food will cause mast cells (a type of immune system cell in the body) to release chemicals into the bloodstream. One of these chemicals is histamine. This reaction causes symptoms that affect a person's eyes, nose, throat, respiratory system, skin, and digestive system.

Signs of allegy includes:

Swelling
Rashes
Tightness in the throat
Wheezing
Cough
Nausea
Vomitting
Stomach pain
Diarrhoea

Peanut allergy

An allergy could be mild or severe.

A serious food allergy case can cause anaphylaxis. Which is a sudden, severe allergic reaction whereby several problems involving the skin, breathing, digestion, heart, and blood vessels occur all at once. A person's blood pressure can drop, breathing tubes can narrow, and the tongue can swell.

If you're aware that you have such severe allergy to something, please be very careful. We suggest you write up a plan that can be used for during emergencies. Or have special medicine which can prevent the above mentioned allergy symptoms from getting worse ready by your side.

A note to all MOMS,

If your kids are allergic to a certain kind of food, never allow your child to have any of that particular kind of food. Even if it's only a very tiny bit of that food, it can make your kids fall sick.

Many kids outgrow allergies to milk and eggs as they grow older. However, severe allergies to foods like peanuts and seafood (often shrimp) last a lifetime.


TAKE CARE PEOPLE! ALLERGIES ARE HORRIBLE, DON'T MESS WITH THEM!

Our immune system

Basically, an Immune System is a body system which helps fight off sickness. It is made up of a network of cells, tissues, and organs that work together to protect the body.


White blood cells, also called leukocytes are referred to as germ-fighting cells. There are 2 basic types:

Phagocytes: Chew up invading germs

Lymphocytes: Allow the body to remember and recognize previous invaders


Leukocytes can be found in many places in your body. For instance, the spleen, an organ in your belly that filters bloody and helps fight infections, and the bone marrow, a thick and spongy jelly inside your bones.

When you have a sore throat, swollen "glands" can be seen on the sides of your neck. Those are actually lymph nodes, and they contain clusters of immune system cells. Lymph nodes are small and round and barely noticeable. However, when your immune system is at work, they appear to be swollen.

Lymph nodes are present beside your neck, behind your knees, in your armpits, and in your groin. They contain lymph, a clear fluid with leukocytes, and remove germs that could harm you.

Falling sick is inevitable. But, with such great system in our body, we get well again. However, not everyone has a perfect immune system. Some of you may have a problem with your immune system. One kind of problem will be allergies , whereby the immune system overreacts and mistake something harmless as something dangerous to the body.

We will touch on Allergies in our next post!

Check it out!!

Reference

http://kidshealth.org/PageManager.jsp?lic=1&article_set=53862&cat_id=20607

The Little Girl Who Fell Down

Immunology for Kids

Featuring ShaSha as "The Little Girl"

One happy sunny afternoon, Shasha was playing with her pretty pink balloons in the garden. Suddenly, she tripped over a tiny rock and fell onto the dirty ground.

Shasha cried, "BOO HOO HOO!"

She stood back up and realised she had a tiny cut on her right knee and it was bleeding. Not only was there blood on her knee, there was also dirt from the ground. As you can see in the circle in the picture above, the cut on her knee, causes her skin(epithelial barrier) to be broken and this allows the bad and ugly bacteria to enter her wound and enter Shasha's body.We don't want bacteria to enter Shasha's body because bad and ugly bacteria will cause Shasha to fall sick and feel unhappy.

So what does the body do to prevent Shasha from falling sick?

In Shasha's body and also all of our bodies, we have a special "army of cells" in our immune system that helps us fight bad and ugly bacteria so that we will not fall sick. As you can see in the above picture, Shasha's broken skin is shown. Since bad and ugly bacteria is found everywhere, when Shasha fell, some of the bad and ugly bacteria, which we cannot see with our naked eyes, got stucked onto her wound. Remember I mentioned that out body has a special "army of cells" which fights and kills the bad and ugly bacteria? Yes! The purple round happy cells are called leukocytes which consists of lymphocytes and monocytes and they are the good guys in our body! They will defend our body by killing the baddies!

Even though our body has the necessary mechanisms to fight the "baddies" which are the bad and ugly bacteria and microbes that can cause infections and also cause you and Shasha to fall sick, it is also important for Shasha and the rest of us to clean the wound and apply proper dressing. This is so that we kill the bad guys before they even have the chance to enter our body.That is why Mom cleaned Shasha's wound and put on a pretty plaster on her wound. Shasha then continued to play in the garden with a smile on her face.

And so the day is saved by Mom and the good guys in our immune system!

THE END

Antigen-Antigen receptor interaction

Part 3: Antigen-Antigen receptor interaction

Antigen-antigen receptor interaction

Antigens interact with antigen receptors on the basis of complementary shapes and intermolecular forces. They do not bind covalently but by protein-protein interactions.


Intermolecular forces - Forces that act between stable molecules or between functional groups of macromolecules. Intermolecular forces (the weakest of which are van der Waals forces) include momentary attractions between molecules, diatomic free elements, and individual atoms.


The 5 kinds of protein-protein interactions:

• Hydrogen bonding - Chemical bond which arises from the attraction between the slight positive charge on a hydrogen atom and a slight negative charge on a nearby fluorine, oxygen or nitrogen atom. Weak bonds, but found in great quantities in proteins, nucleic acids, and other biological macromolecules.
  
  


• Ionic interactions - Chemical bond formed by electrostatic attraction resulting when one atom “donates” valence electron(s) to another atom, resulting in filled energy shells for both atoms involved in the interaction.



• Hydrophobic interactions - An interaction between a hydrophobic (''water-hating'') part of a molecule and an aqueous environment




• Dipole-dipole - The interaction of two atoms, molecules, or nuclei by means of their electric or magnetic dipole moments.




• Van der Waals - The attractive or repulsive force between molecules (or between parts of the same molecule) other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules.

Covalent bond - A form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, or between atoms and other covalent bonds.

Cross-reactivity

Cross-reactivity - The binding of antibody to similar epitopes on other antigens / proteins.

For examples, when an antibody bings more strongly to say, antigen A than to antigen B, it is said to be more specific for antigen A compared to Antigen B.

The binding strength of antibodies to antigens depend on two factors:

1. Antibody affinity - Strength of binding of an antibody binging site to an epitope. It is also the sum of all the attractive and repulsive forces. It depends on opposing atomic groupings and the shape of combining site to the epitope.




2. Antibody avidity - Total strength of binding between a miltivalent antigen and a multivalent antibody. It is also the sum of individual binding affinities.
   

Multivalent - Having several sites of attachment for an antibody or antigen.

References:

http://student.biology.arizona.edu/honors2004/group03/Vocabulary.htm
http://www.answers.com/topic/dipole-dipole-interaction
http://www.abcam.com/index.html?pageconfig=resource&rid=11279&pid=11287
http://www.st-andrews.ac.uk/~ulf/levvdw.gif
http://upload.wikimedia.org/wikipedia/commons/5/59/Dipole-dipole-interaction-in-HCl-2D.png
http://chemtools.chem.soton.ac.uk/projects/emalaria/page_imgs/content/ionic.gif

Antigens and Antigen Receptors

Part 2: Antigens and Antigen Receptors

What is an antigen?


An antigen is a substance that stimulates the production of antibodies and can be recognised by a B cell receptor or antibody, or a T cell receptor. As mentioned before, the part of the antigen which comes into contact with the antigen receptor is called the epitope or antigenic determinant.

Antibody - A protein that fights infection.

2 types of Epitopes

A linear or a sequential epitope is an epitope that is recognized by antibodies by its linear sequence of amino acids, or primary structure.

In contrast, most antibodies recognize a conformational epitope that has a specific three-dimensional shape and its protein structure. Conformational epitopes are recognised by antibodies. When the molecule is denatured, the epitope is destroyed due to hanges in its 3-dimensional configuration.

Do B and T cell receptors recognise the same antigen?

B cell receptors (antibodies) can recognise both linear and conformational epitopes. Take note that B cell receptors which recognises conformational epitopes (on native molecules) will not recognise the denatured protein.

T cell receptors recognise short linear peptides presented by MHC molecules.

MHC stands for Major Histocompatibility Complex. It is a complex of genes coding for a large family of cell-surface proteins that bind peptide fragments of foreign proteins and present them to T cells to induce an immune response.

References:

http://www.web-books.com/eLibrary/Medicine/Physiology/Immune/Antigen_Antibody.gif
http://img.photobucket.com/albums/v305/Aegeri/immunodiagram.jpg
http://www.cartage.org.lb/en/themes/sciences/lifescience/GeneralBiology/Immunology/ImmuneSystem/OrgansCells/Cellsandtissues/BT.gif
http://upload.wikimedia.org/wikipedia/commons/thumb/f/f7/B_cell_activation.png/300px-B_cell_activation.png

Adaptive/Acquired Immunity

Part 1: Adaptive/Acquired Immunity

As shown in the above flowchart, our immunity can be divided into two categories, namely, innate and adaptive/acquired. So what exactly is immunity? Simply put, it is a body's ability to resist a disease.

Innate immunity refers to non-specific defense mechanisms that come into play immediately or within hours of an antigen's appearance in the body.

Adaptive/Acquired immunity refers to antigen-specific immune response. The adaptive immune response is more complex than the innate. Adaptive immunity also includes a "memory" that makes future responses against a specific antigen more efficient. [This will be our main focus]

Differences between innate and adaptive immunity [click to enlarge]

More about adaptive immunity

Adaptive immunity is carried out by B cells and T cells.

Both B cells and T cells are lymphocytes. A lymphocyte is a type of white blood cell [White blood cells, or leukocytes, are cells of the immune system defending the body against both infectious disease and foreign materials] in the vertebrate immune system. T cell can be further divided into helper T cells and cytotoxic T cells. Helper T cells activate other immune cells while cytotoxic T cells kill infected or mutated cells. B cells produce antobodies.

Adaptive immunity can be distinguished by its specificity and memory.

Specificity is provided by antigen receptors on B and T cells. Memory is provided by long-lived memory cells that are formed during the infection and persist for a long time.

Recognition by the adaptive immune system

There are antigen receptors on B cells and T cells that recognise epitopes on antigens. Each B and T cell has a unique receptor that will bind very specifically to a particular antigen.

• B cells - B cell receptors and antibodies
• T cells - T cell receptors
  

Receptor - A nerve ending that is sensitive to stimuli and can convert them into nerve impulses. Like a "receiving device". The diagram below simply illustrates how a receptor generally works.

Epitope - An immunologically active binding site on an antigen to which an antibody or a B or T cell receptor becomes attached.

Primary and Secondary immune responses

Primary immune response - The immune response occurring on the first exposure to an antigen, with specific antibodies appearing in the blood after a multiple day latent period.

Secondary immune response - The immune response occurring on second and subsequent exposures to an antigen, with a stronger response to a lesser amount of antigen, and a shorter lag time compared to the primary immune response.

References:

http://faculty.ircc.edu/faculty/tfischer/micro%20resources.htm
http://www.biology.arizona.edu/immunology/tutorials/immunology/page3.html
http://www.inimexpharma.com/products/prod_tech_immunity.html
http://www.leiomyosarcoma.info/images/cell_receptor.jpg
http://medical-dictionary.thefreedictionary.com/secondary+immune+response

Welcome!

Hello to you! Are you hungry for some knowledge?? Dying to know more about say, immunology? If so, you've come to the right place and even if you're not, it wouldn't harm you to read on and gain some extra useful information. People are pretty dumb nowadays. You can surely pick up some really chim terms here unless you're aleady a doctor or something along that line :D So anyway, as part of our Immunology Assignment at Ngee Ann Polytechnic, we, the FREAKS (not geeks) are here to share some immuno-related stuff with you. Serious business ahead...Do you know that you will die a horrible DEATH without a healthy working immune system? MUAHAHAHAHAH!! So please do check out our blog regularly! What's there to lose anyway!

P.S. Keep in mind that we are only human, FREAKS as a matter of fact so excuse us if we make mistakes :) MUACKS!