How the Rapid FDA-Approved Coronavirus Testing System Works (ieee.org) 23
Tekla Perry writes: In 2001, a rapid, easy-to-use, PCR-based testing system for biological testing was still in prototype form when letters containing anthrax spores started arriving in the mailboxes of journalists and senators. Its creators at startup Cepheid quickly adapted it to test for anthrax, and now it is used to run that test as part of U.S. mail sorting systems. The tool, now called GeneXpert, is also installed in health care facilities around the world. And cartridges to allow these systems to test for COVID-19 -- the first rapid such test approved in the U.S. -- are rolling out. The technology relies on microfluidics, and takes about 45 minutes to run an extremely accurate and sensitive test. Cepheid co-founder Kurt Petersen, now an angel investor, explains how it works. "The test cartridge contains microfluidic channels; these are made out of plastic using high-precision injection molding," explains Petersen. "All the chemicals needed for the process are stored in chambers within the system. In the center of the cartridge, a rotary valve turns to open different pathways, while a tiny plunger -- like a syringe -- moves fluids in and out as needed.
So, the plunger pulls the sample into the center, the valve rotates, and the plunger pushes it into another region of the cartridge to do an operation on it. The system can do that multiple times, moving the sample to different regions with different chemicals, extracting RNA, mixing it with the reverse transcriptase that synthesizes complementary DNA that matches the RNA, and eventually pushing it into PCR reaction tube, where rapid heating and cooling speeds up the process of copying the DNA. Each new copy of the DNA gets a fluorescent molecule attached, which allows an optical system to determine whether or not the targeted gene sequence is in the sample."
So, the plunger pulls the sample into the center, the valve rotates, and the plunger pushes it into another region of the cartridge to do an operation on it. The system can do that multiple times, moving the sample to different regions with different chemicals, extracting RNA, mixing it with the reverse transcriptase that synthesizes complementary DNA that matches the RNA, and eventually pushing it into PCR reaction tube, where rapid heating and cooling speeds up the process of copying the DNA. Each new copy of the DNA gets a fluorescent molecule attached, which allows an optical system to determine whether or not the targeted gene sequence is in the sample."
Sounds a lot like DRM (Score:2)
Is this seriously the K-cup version of a PCR test? Does this thing actually do.testing better, or use some novel process, or really be better or faster or cheaper than what I can do with a stepper and a spread of test vials?
Legitimately asking if anyone who isn't an investor would be willing to explain the technology here.
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Is this seriously the K-cup version of a PCR test? Does this thing actually do.testing better, or use some novel process, or really be better or faster or cheaper than what I can do with a stepper and a spread of test vials?
Legitimately asking if anyone who isn't an investor would be willing to explain the technology here.
I'm no scientist, but looking at the number of tests being processed I'm pretty sure it is faster. As for better or cheaper, I'm not sure, but you only get to pick two.
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The major problem with existing testing is lack of materials since everything is model-specific.
This device seems to have the same problem times ten.
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Individual tests seem faster than PCR, although their largest system looks like it can only do 500 tests per 24 hours. It might also be less error-prone than standard PCR.
It’s something, and a cool concept, but no panacea for the testing challenges. Not sure what the relative benefit is if you need to perform 2,000 tests per day.
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The Infinity system has 80 instrument slots, full cartridge handling automation, and has a throughput of ~2500 tests per day.
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Thanks; the website looked liked it maxed out at 16.
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You have to dig a bit but here's the big automation system, they built this specifically for this kind of event, it didn't get uptake but I hear from friends working in Sunnyvale that they've suddenly had call to ship a few of these - https://www.cepheid.com/en_US/... [cepheid.com]
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Re:Sounds a lot like DRM (Score:5, Interesting)
The Gx Best part about the Gx cartridge system is that sample handling is significantly reduced over the multi-step RT-PCR tests that a standard laboratory runs. Theres an ultrasonic horn that can lyse pretty much anything (it uses cavitation in the liquid to break open the spores/cells/capsids) so sample prep is essentially just get some of the biological material into the sample port, and put it into a Gx machine. The system uses an exactly specific DNA flourescent maker to tag only the exact DNA sequence, and it ignores any other DNA strand, so you dont have to filter out byproducts.
With a laboratory standard RT-PCR test first you have to wash the swab to get some of sample biological material out, then do some fancy chemistry to extract the RNA (leaving out any DNA), and that step requires a centrifuge. Only after that can you run the Reverse-Transcripease chemistry (the "RT" part of RT-PCR) to convert the RNA to DNA. After that process, then you run PCR to make copies of the DNA, and then you can run the assay Each of these are discrete steps for a technician.
The test cartridge contains all of the reagents to perform the sample conversion, for that reason they are single-use, not DRM. You also wouldn't want to contaminate a test with old material from a prior run, so disposable cartridges are the right solution.
Re:Sounds a lot like DRM (Score:4, Insightful)
Yup, except the "coffee" replaces a multi-step process and the "water" is a potentially highly infectious, deadly agent that you'd rather not let loose in your lab multiple times if you can keep it in isolation through the whole process.
These machines are designed to run in clinical and hospital settings without the need for highly trained personnel or intensive sanitation procedures. You don't want to risk sample cross-contamination or letting these genii out of their bottles to infect hospital staff.
The FDA Graveyard ... (Score:3, Insightful)
For decades, the FDA’s archaic rules [city-journal.org] have been delaying medical progress and consigning tens of millions of Americans to an “invisible graveyard.” Now a very small part of the graveyard has suddenly become visible: the people dying of Covid-19 because of one bureaucratic obstruction after another to providing tests, masks and other protective equipment.
Re: The FDA Graveyard ... (Score:4, Informative)
Re: The FDA Graveyard ... (Score:5, Insightful)
The FDA is in a tough spot. On the one hand you have people complaining (and, possibly dying) because they move too slowly, and on the other hand you have people suing (and, possibly dying) because they approved something too quickly and were wrong.
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The FDA regulations for nearly everything regulated include a large pile of rules that basically say 'write down what you say you are going to do to build thing X, figure out how to prove that you in fact built thing X the way you said you were going to do so, and then actually use your tests to prove that each individual thing X was built the way you said it was going to be built. And keep all those records until X number of years after you no longer manufacture thing X'. Those rules
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I'm all on board for eviscerating the FDA for being a road block but...
Abbot Labs is now turning out 1 million test kits a week.
There are 350 million Americas, depending on what source you look at.
At 1 million tests a week, that's 350 weeks to provide just one test to every American, that's 87 months, or.7 years. Triple that production rate and you are look at 29 months. Since the reality is people will need to take more than one test, the entire "need to test everyone" testing controversy is just a distrac
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For decades, the FDA’s archaic rules [city-journal.org] have been delaying medical progress...
At any given time, FDA testing is intended to represent a gold standard for qualifying new compounds and devices. The plodding slowness of the testing process we have been using up to now has been criticized for years, but no one wants to take the plunge on being first to risk applying newer test processes. Until there's a global crisis...
Where is Theranos? (Score:2)
Weren't those machines FDA approved?
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Where is Theranos? Weren't those machines FDA approved?
Theranos did get one FDA approval for it's 1 drop of blood test for herpes, later found to be terribly insensitive and unspecific. To the FDA's credit, they had applied for approval for 15 different tests.
The difference I'm seeing here is details. Theranos tried to hide their bullshit behind a wall of "super-secret speshul proprietary no-lookie inside the black box" smokescreen. This company is being veerrry detailed about how their system works, carefully explaining that the machine is still doing all t
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Yeah? (Score:2)
Investor who stands to make a fortune if product accepted says product is "Accurate". Well, there's a surprise.
What's the sensitivity; what's the specificity? "Accurate" is just marketing.