Samira Farouk, MD, MS, FASN Profile picture
Transplant Nephrologist + APD @ISMMSKidney | @Neph_SIM | @RenalFellowNtwk | @NephJC_Podcast | @CliniTransplant | @RWJMS | @Princeton '07 | Philly sports 🏳️‍🌈
Prabhat Chauhan Profile picture 1 added to My Authors
17 Jul

Another #immunosuppression #tweetorial...spotlight today on #belatacept today

How do you say it? @Babybel @MedTweetorials

Belatacept is the FUSION protein that has been the @NKOTB in #kidneytransplant - having been approved for use in 2011.

What's fused?

1. Human IgG1 Fc fragment
2. Extracellular domain of cytotoxic T-lymphocyte–associated antigen 4 (CTLA-4)

The goal of this fusion protein? Disrupt Signal 2⃣ of the 3⃣-Signal T-cell activation pathway

Signal 2 = Binding of CD28 (on T-cell) to B7-1/B7-2 (on APC)

This important step is called co-stimulation and is necessary for T-cell activation…
Read 11 tweets
14 Apr

As kidney replacement therapies (KRT) have become a strained and limited resource during the #COVID19 pandemic, here is a quick #tweetorial on how these treatments work:

What is the main mechanism by which clearance is achieved during intermittent #hemodialysis?

KRT has 2 powers:
1⃣Clearance (removal of solutes, like potassium 🍌)
2⃣Volume removal 💧

...and it comes in 2 flavors:
3/ How does the potassium go from 7.2 meq/L to 4 after an intermittent #hemodialysis (iHD) session?

Chemistry 101: DIFFUSION!

Solutes are cleared via diffusion as they move ⬇️ their concentration gradient across a SEMIPERMEABLE membrane

DOI: 10.1056/NEJMc1301071
Read 16 tweets
17 Mar
1/ In light of the conversion of many of our interactions to virtual experiences, a #tweetorial on @zoom_us features that may enhance your teaching/conferences/meetings etc (No COI to disclose)

Which of the following features does Zoom have?

#MedEd #COVID19 #COVIDー19
2/ Answer: All of the Above

Step 1: Log into your @zoom_us profile and personalize it to activate the features you want Image
3/ The toolbar at the top or bottom of your screen will give you access to the Chat, Share Screen, Polling, Breakout Groups + Whiteboard

Click "Participants" to see who's in the meeting ImageImage
Read 10 tweets
12 Nov 19
1/ A continuation #tweetorial from my last one introducing human leukocyte antigen (#HLA) , the cell surface antigen...

Below, let's briefly review basics of #Luminex testing & "cross-matching."

What/who is Luminex?
2/ In this #tweetorial, we'll answer 3Qs that help us assess a #kidneytransplant recipient's immunological risk:

1. Does this recipient have #DSA* (against HLA-antigens) ?
2. Can the antibodies bind?
3. Can the antibodies activate complement?

*DSA: donor specific antibodies
3/ Q1: How do know if the recipient's serum contains DSA against HLA-antigens?

A1: #Luminex testing, a solid-phase (BEAD) based assay. To perform the test, take the recipient's serum and pipette it into multiple wells - each well has beads coated with #HLA antigens...
Read 12 tweets
6 Nov 19
Starting the morning with “The Sciece of Learning” with Peter C Brown at the new #MedEd Workshop #KidneyWk

3 Big Ideas:
Additional testing may be more effective than additional studying #MedEd #KidneyWk
Spaced practice allows time for consolidation, strengthens connections, updates learning...and sleep is important! 😴 #KidneyWk
Read 5 tweets
27 Oct 19
1/ A short #tweetorial introducing human leukocyte antigen (HLA) and important and often confusing topic in #transplantation #kidneytransplant

#FOAMed @MedTweetorials

What is an "HLA"?

HLAs = cell surface proteins encoded by highly polymorphic major histocompatibility complex (MHC) genes on Ch 6 🧬

In #transplantation, HLA proteins are #polymorphic antigens ➡️ alloreactive trigger for the immune response ➡️ can ultimately lead to organ #rejection ☠️
3/ The 2 primary classes of MHC molecules are 1⃣ and 2⃣.

Class 1⃣ MHC are found on the cell surface of ALL nucleated cells + platelets. Their role is to present intracelleular peptide fragments to CD8 #Tcells
Read 8 tweets
15 Sep 19
1/ Continuing the #immunosuppression #tweetorial series...@MedTweetorials

Today's player: #mTORi, mammalian/mechanistic target of rapamcyin inhibitors

Rapamcyin was @US_FDA approved for #kidneytransplant in 2003.

It was isolated from a soil sample from which island in 1975?
2/ Meet mTOR, a phosphatidylinositol 3-kinase (PI3)-related kinase (adds a phos). mTOR adds a phosphoryl group to serine/threonine residues.

It is a key component of the complexes mTORC1 and mTORC 2 - which regulate processes including cell growth, proliferation, and survival.
3/ mTOR inhibition blocks "Signal 3" of #TCell activation - reducing cytokine dependent cell proliferation and activation.

Take a look at all 3 signals below 👇🏽…
Read 11 tweets
30 Jul 19

Here's another #immunosuppression #tweetorial. This time, a focus on mycophenolic acid (MPA). #MMF #Mycophenolate

The main mechanism of action of MPA is inhibition of which of the following:
2/ Let's meet the players. Mycophenolate mofetil (MMF, left) is a prodrug of MPA while mycophenolate sodium (MPS, right) is an enteric-coated salt of MPA.

MMF administration releases MPA in the stomach, while mycophenolate sodium (MPS) releases it in the small intestine.
3/ MPA is often referred to as an "anti-metabolite", which means a substance that interrupts a metabolic process within cells.

The process that MPA interrupts here: PURINE SYNTHESIS
Read 9 tweets
25 Jun 19

A brief #tweetorial on the calcineurin inhibitors #CNI and their toxicities. Let's start with a quick poll.

Which of the following describes the main mechanism of action of #CNI?

On to the mechanism of #CNI. Calcineurin inhibitors bind to the "immunophiliins" for which they are named. Cyclosporine (CsA) binds cyclophilin and tacrolimius(FK506) binds FK binding protein.

The CNI-immunophilin complex is the superhero which then inhibits calcineurin
Meet calcineurin, whose superpower is a calcium-dependent PHOSPHATASE: enzyme that uses H2O to cleave phosphoric acid into a phosphate ion and an alcohol (read: removes phos)

Normally, calcineurin dephosphorylates NFAT - allowing it to freely swim into the nucleus.
Read 10 tweets