Monday, September 18, 2017

Ocular toxoplasmosis and HIV

Here are some fun facts about Ocular Toxoplasmosis and HIV!

Ocular toxoplasmosis usually causes a retinal lesion with inflammation, giving the classical "headlight in the fog"  appearance.

Headlight is the lesion and the fog is due to the inflammation (WBCs).

HIV being an immunodeficient condition, there are lesser number of WBCs and hence there's no fog - Just the headlight.

The drug of choice for treatment of ocular toxoplasmosis is pyrimethamine.

However, it is contraindicated in pregnancy and HIV due to the risk of megaloblastic anemia and neural tube defects, respectively.

In pregnancy, spiramycin is preferred.

In HIV, the preferred drugs are clindamycin, azithromycin or quinolones.

- Written by Dr²

Medicollabowesome: Topic of the month - Diabetes Mellitus


Sunday, September 10, 2017

Enucleation, Evisceration & Exenteration

In this post, we will look at the definition, indications and some few details regarding these 3 ophthalmologic surgeries. 

Saturday, September 9, 2017

Cytochrome P450 3A4



Hello everyone!

Today lets discuss the Cytochrome P450 3A4
It is the microsomal enzyme involved in metabolism of xenobiotics. Maximum number of drugs are metabolised by CYP 3A4 in our body.

Here’s how you  remember the substrates and the inducers of the enzyme:

“In emergency Straightaway give a CPR and ACT SaNely

The inducers are:
S: St John Wort
CPR: Carbamazepine, Phenytoin, Phenobarbitone, Rifampicin


The substrates are:
ACT SaNely

A-Amiodarone
A-ACT drugs(Anti Histamines) 
*A-Astemizole
 *C-Cisapride
*T-Terfenadine
C- Cyclosporine
T- Tacrolimus
S- Statins
N-Navirs (protease inhibitors)




And how do we remember the inhibitors?

Shout “Fire in the Hole!”
Fluconazole   Ketoconazole
and Ritonavir and Erythromycin
Also you can have some grapefruit juice to chill out! Grapefruit juice is also a Inhibitor of CYP3A4.

That’s all
Thank you,
Chaitanya Inge

Tuesday, September 5, 2017

Drug interaction

Hello :)

Definition:-
Modification of response  to one drug by another drug or non drug (like food ,beverages like alcohol,smoking) when they are administered simultaneously or in quick succession  .


Factors for drug interactions:-
1.Multiple drugs for same disease.
2.Multiple prescribers.
3.Multiple diseases.
4.Poor patient compliance .
5. Drug factors like it is not palatable or too many in frequency .
6.Multiple unknown action of drugs.
7. Most imp is patients age .

Effects of drug interaction:-
1.Quantitative i.e Increase  or decrease the response intensity.
2. Qualitative:- abnormal /different type of response.

Mechanism of drug interaction :-
A.Pharmacokinetic interactions include,
 1.Absorption (either complex formation ,pH change ,or alteration in motility of GIT.)

2. Distribution:- (displacement from plasma protein binding site + inhibition of metabolism /or excretion)

3. Metabolism:- ( induction of enzymes or inhibition of enzymes or hepatic blood flow)

4.Excretion:- ( alteration in urine pH, Competition for active secretion ,renal blood flow)

B. Pharmacodynamic drug interactions include,
1.Antagonism
2. Summation
3.synergism

C.Drug interaction before administration:-
Either mixing before administration.
Or, exposure to light in some cases. (Like sodium nitroprusside).


-Upasana Y.

Blood retinal Barrier

Hello :)

There are two blood retinal Barrier (BRB) :-

1. Outer blood retinal Barrier - Formed by tight junction of retinal pigmented epithelium.

2. Inner blood Retinal Barrier - Formed by Muller cells and pericytes surrounding the lining of microvasculature.

That's all for today.
-Upasana Y. :)

Saturday, August 26, 2017

Immunology question

Hola awesomites!!

So, this is answer of our previous question. Lets have a look into it.

Q1)Which of the following features is not shared between T cells and B cells
a)Antigen specific Receptors
b)Class 1 MHC expression
c)Positive selection during development
d)All of the above

Answer is
C) Positive selection during development

Explanation:

Positive selection:
Site is thymic cortex.
-T cells having affinity for MHC molecules are selected since T cells having affinity for MHC molecules can interect with APC  and one who don't have recognisation is killed

Negative selection:
Site:Thymic medulla
Selected T cells are sent to medulla,where there affinity for self antigens are tested.If the have affinity they are programmed to death.

Incase of B cells,if they recognize self antigens they do not undergo death instead there receptors are changed by the process called as "Receptor editing" .If receptor editing dose not take place,then apoptosis takes place.This is negative selection of immature B cells. B cells negative selection occurs in the bone marrow

Both T-cell and B-cell have TCRs and BCRs respectively.
Class I MHC is expressed on both T cells and B cells..

Stay awesome:)

~Ojas