T-b-a-blr-blog - Untitled

Side effects of drugs commonly given to the elderly

For sleep aid do not give barbituates or diphenhydramine (1st gen antihistamine). Instead, give Ramelteon.  

Antibodies (Human)

The ‘foot’ (bottom) of the antibody is known as the Fc fragment - binds to cells, binds to complement = effector function (kills or removes antigen)

The top (antigen binding) is the Fab fragment

Chains are held together with disulphide binds

Associated molecules allow intracellular signalling 

Normally 3X constant heavy chain domains per chain and a hinge region (except μ and ε which have 4 and no hinge region)

Classes of Immunoglobulins

The five primary classes of immunoglobulins are IgG, IgM, IgA, IgD and IgE,  distinguished by the type of heavy chain found in the molecule. 

IgG - gamma-chains

IgMs - mu-chains

IgAs - alpha-chains

IgEs - epsilon-chains

IgDs - delta-chains.

Differences in heavy chain polypeptides allow different types of immune responses. The differences are found primarily in the Fc fragment. There are only two main types of light chains: kappa (κ) and lambda (λ), and any antibody can have any combination of these 2 (variation).

IgG 

monomer

Gamma chains

70-85% of Ig in human serum. 

secondary immune response 

only class that can cross the placenta - protection of the newborn during first 6 months of life

principle antibody used in immunological research and clinical diagnostics

21 day half life

Hinge region (allows it to make Y and T shapes - increasing chance of being able to bind to more than one site)

Fc strongly binds to Fcγ receptor on phagocyte - opsono-phagocytosis

Activates complement pathway

IgM

Serum = pentamer 

Primary immune responses - first Ig to be synthesised

complement fixing 

10% of serum Ig 

also expressed on the plasma membrane of B lymphocytes as a monomer - B cell antigen receptor

H chains each contain an additional hydrophobic domain for anchoring in the membrane

Monomers are bound together by disulfide bonds and a joining (J) chain.

Each of the five monomers = two light chains (either kappa or lambda) and two mu heavy chains.

heavy chain = one variable and four constant regions (no hinge region)

can cause cell agglutination as a result of recognition of epitopes on invading microorganisms. This antibody-antigen immune complex is then destroyed by complement fixation or receptor mediated endocytosis by macrophages.

In humans there are four subclasses of IgG: IgG1, IgG2, IgG3 and IgG4. IgG1 and IgG3 activate complement.

IgD 

B cell receptor

<1% of blood serum Ig

has tail pieces that anchor it across B cell membrane

forms an antigen specific receptor on mature B cells - consequently has no known effector function (don’t kill antigens, purely a receptor) (IgM as a monomer can also do this)

IgE 

Extra rigid central domain

has the most carbohydrates

IgE primarily defends against parasitic invasion and is responsible for allergic reactions.

basophils and tissue mast cells express very high affinity Fc receptors for IgE - mast cells then release histamine

so high that almost all IgE is bound

sensitizes (activates) mucosal cells and tissues 

protects against helminth parasites

IgE’s main purpose is to protect against parasites but due to improved sanitation these are no longer a prevalent issue across most of the world. Consequently it is thought that they become over activated and over sensitive while looking for parasites and start reacting to eg pollen and causing allergies.

IgA

Exists in serum in both monomeric (IgA1) and dimeric (IgA2) forms (dimeric when 2 Fcs bind via secretory complex)

15% of the total serum Ig.

4-7 day half life

Secretory IgA2 (dimer) = primary defense against some local infections

Secreted as a dimer in mucous (e.g., saliva, tears)

prevents passage of foreign substances into the circulatory system

Isotype: class of antibody (IgD, IgM etc)

Allotype: person specific alleles 

Idiotype: (hyper) variable region - antibody specificity 

Who wants a box of chocolates when you can have a petri dish of bacteria?

Tumblr room🌹

CAMP test for the identification of Streptococcus agalactiae (group B). 

(A) Streptococcus (group B) shows a positive CAMP reaction arrow-shaped zone of enhanced hemolysis .

(B) Streptococcus pyogenes (group A) shows a negative reaction when inoculated at a right angle to

© Staphylococcus aureus.

Archaea

Archaeans are single-celled and join bacteria to make up the Prokaryotes.  The Archaea classification is a very recent discovery, due to the similarities in appearance and behaviour to bacteria they weren’t separated until the late 1970′s. They mostly live in extreme environments and can be sub grouped: 

Methanogens - produce methane gas as a waste product of their “digestion,” or process of making energy.

Halophiles - live in salty environments.

Thermophiles - live at extremely hot temperatures.

Psychrophiles — those that live at unusually cold temperatures.

Like bacteria, archaea lack a true nucleus. Both bacteria and archaea usually have one DNA molecule suspended in the cell’s cytoplasm contained within a cell membrane. Most, but not all, have a tough, rigid outer cell wall.

use a variety of substances for energy, including hydrogen gas, carbon dioxide and sulfur. 

many archaea thrive in conditions mimicking those found more than 3.5 billion years ago. [eg oceans that regularly reached boiling point — an extreme condition not unlike the hydrothermal vents and sulfuric waters where archaea are found today]

A fib =  no p wave 

Hope it helps @shreeparn  :)

My revised pnemonic for ADP ribosylation A-B toxins

Boring     and      serious      people score high in usmle…

Bordetella pertussis and B.cereus  increases   cAMP by inhibiting Gi

Cool    and     Vibrant   people  also score high…

E. coli  and Vibreo cholerae increases cAMP by  activating Gs

Exception: Please please please remember that  Bacillus anthracis has an edema factor which it self acts as adenylate cyclase…. no ADP ribosylation involved..so hence  cAMP level increases.