Abdullah Ahmed

N’oublie pas de vivre | Research fellow, Illinois Eye & Ear Infirmary @uicovs @UIHealth | AIMC 23' @allamaiqbalmed

[American Academy of Ophthalmology @aao_ophth]

From early keratitis to corneal dystrophy to common ectasias — this YO guide breaks down what you need to know about three core #cornea disorders. Whether you’re on call or prepping for fellowship, these pearls are your foundation. #YOInfo https://t.co/LKYq4pEWkN

[Mike Mehlman @mehlman_medical]

Someone asks about how to prevent burnout…

Gym daily acts a diffuser of “stress” of work. Gym 6 days a week is basically mandatory and is important counterbalance.

People who burn out aren’t interested in what they’re doing. It’s not about number of hours. It’s about being interested in the work you’re doing toward specific goals you’ve got.

You won’t feel motivated all of the time doing even stuff you like, but if you DO like the path you’re on but just are having off days, you need to have discipline and act/work regardless of how you feel.

TLDR: The most successful people do what needs to be done regardless of how they feel.

[Abdullah Ahmed @abdullahmujadad]

@Haseebfaiz7 Congratulations 🎉

[Abdullah Ahmed @abdullahmujadad]

@asad_lak @NoorusabahAhmad @uiowaeye Mashallah many many congratulations @NoorusabahAhmad

[Abdullah Ahmed @abdullahmujadad]

Dr Sattar ❤️

[Radiological Students’ Association of Pakistan @radsapakistan]

🎯 RSAP Publication Alert!

🎉 We’re delighted to announce the publication of a rare case study, ‘Concurrent Acute Pancreatitis, Pneumoperitoneum, Pneumoretroperitoneum, and Pneumomediastinum Following ERCP-Related Perforation’ in Radiology Case Reports (Elsevier)!

[Abdullah Ahmed @abdullahmujadad]

@ezaajaved012 Congratulations

[Abdullah Ahmed @abdullahmujadad]

@aud_cheema It’s still an achievement. You got this. And best of luck 🤞

[Abdullah Ahmed @abdullahmujadad]

@naeemafzal_ @dr_alisarwar @Novartis The problems are arising because of improper extraction of smaller vials. That’s why people are getting endophthalmitis. Otherwise avastin is AAO certified drug for priferative diabetic retinopathy. There’s no problem with using it !

[Abdullah Ahmed @abdullahmujadad]

@naeemafzal_ @dr_alisarwar @Novartis Avastin is usually prescribed because it is the most budget friendly option that patient can actually afford unlike lucentis or eyelia. Companies in Pakistan use a 200mg vial and then make smaller 5-10mg solutions from it.

[Abdullah Ahmed @abdullahmujadad]

@naeemafzal_ @dr_alisarwar @Novartis The problem is not Avastin. It is anti-angiogenic just like lucentis for stopping proliferative disorders/tumors of kidney, lungs, prostate,liver,eye etc cz that’s what anti-angiogenic agents are meant to be used for.

[Abdullah Ahmed @abdullahmujadad]

@AbdSaeedxD Congratulations 🎉

[Abdullah Ahmed @abdullahmujadad]

Best use of biochem in practical life ;\

[Niko McCarty. @NikoMcCarty]

Day 14 of great synthetic biology papers. Storing a video in DNA.

“CRISPR–Cas encoding of a digital movie into the genomes of a population of living bacteria,” by Shipman et al. (2017).

This is the GIF that made synthetic biology go viral. But how did it actually happen?

*****

DNA is an incredible way to store information.

It is information dense (it can store nearly 1.5 terabits per square millimeter of space, 800-times more dense than a hard drive) and extremely durable (last year, scientists sequenced a 2.4 million-year-old DNA sequence from an ice sheet in Greenland.)

Another way to think about this, from my prior essay: "a coffee mug filled with nucleic acids could store all the data produced in the last two years.” (https://t.co/odrTLYBVJC)

Despite the promise of DNA storage, this 2017 paper is the first demonstration of a movie being encoded in a living cell. The video itself is a recreation of Eadweard Muybridge’s running horse movie, which was made by stitching together still images in the late 1800s.

But how was it made?

***

To encode a video inside of living cells, we must first make the DNA.

DNA includes four letters, or nucleotides: A, T, G, and C. Each letter can be used to encode a distinct color, such as white, light gray, dark gray, or black. That is four colors in total; one for each letter. It is possible to encode more colors if you use pairs or triplets of nucleotides.

So that’s our colors sorted. But how do we know which color goes where in the image? In other words, how do we encode spatial information in DNA?

The secret is that DNA itself contains spatial information. We often say things like, “Gene A is encoded on Chromosome 6,” or “Gene B is located upstream of Gene C.”

We can take advantage of DNA's natural spacing to encode our video.

If you wanted to encode a 50 x 50 pixel image in DNA, for example, you would first map out the color of each pixel. Let’s say A = white, T = light gray, and so on. Then, you would synthesize a DNA strand, 50 letters long, for each row in the image. Next, you would insert these DNA strands into the genome in the order of their rows, such that the sequence located furthest upstream corresponds to row 0, and the strand located furthest downstream in the genome corresponds to row 49.

The challenge, of course, is getting the DNA snippets into the genome in the correct order, so that this spatial information is preserved. But there's an easy way to do that, too.

***

If you insert all the strands into the genome at random places, there will be no way to read them back out and reconstruct the image. The spatial information will be lost.

But there is a solution for this. In a 2016 Science paper, Shipman and co. figured out a clever way to insert DNA into the genome in a specific order. This technology has made all the difference for embedding videos in DNA. (https://t.co/QglKlLgPFH)

The 2016 paper shows that two proteins, called Cas1 and Cas2, can grab onto snippets of DNA that are electroporated into cells (literally, a pulse of electricity forces DNA into the cell) and then integrate them in the genome. These special proteins ALWAYS insert DNA in the same location, such that the first DNA snippet is inserted at position 0. A second DNA snippet is inserted at position 0, and the first DNA snippet moves to position 1. And so on.

After Cas1 and Cas2 have inserted dozens or hundreds of DNA strands into the genome, the final outcome is that the DNA snippet located furthest from position 0 must have been the first one to be acquired by the cells!

For the 2017 paper, Shipman synthesized all the DNA needed to encode the various pixels for each frame in the running horse paper. He then "shocked" this DNA into a population of cells. These cells took in the DNA snippets, embedded them in their genomes, and went about their day as if little had happened. When the researchers later sequenced these DNA arrays and averaged the results over mllions of cells, the team was able to retrieve the video’s information with >90% overall accuracy.

This paper is a beautiful demonstration of how a simple discovery (DNA acquisition via Cas1 and Cas2) can be used to capture and inspire people’s imagination. I like it a lot.

[Abdullah Ahmed @abdullahmujadad]

@Dylon_WJLee Wow, Congratulations 🎉

[Abdullah Ahmed @abdullahmujadad]

@RoohAfzaPapi__ Congratsss 🎉

[Abubakar ! @bakkar_ch]

F O R E V E R !

[Abdullah Ahmed @abdullahmujadad]

@dosto_whiskey They have already jumped a lot of verses.

[Troll Football @TrollFootball]

VAR referee watching Arsenal score a 97th min winner

https://t.co/Dk9lFzAjD1

[Abdullah Ahmed @abdullahmujadad]

Relatable af