??? for our du med experts.

[mopinko]

so, i have 2 geeky questions about this mess.

does anyone know what reagents they are having such trouble w? is it really that hard to make? i cant imagine.

also, about this clotting stuff. i have a hairbrained idea.
i was a lab aide decades ago, just as all this mechanized stuff was taking off.
we had a couple of machines that ran a couple of tests, and we had just gotten the sra 12, iirc, that could run a full chemistry. we also got a machine that did most of the cbc.
i remember drawing extra blood to test out those machines.

back in that day, the test we did on clotting factors was a simple one.
a blue topped tube (w anticoaglulating agent), poured the whole blood in a graduated tube, set a timer, and a minute later, you had the sed rate.
i'm guessing that kids these days have no idea how to do a simple test like that.
and i know how things are prolly moving in these places.
i'm thinkin if it was me in there, i would set that tube on a rack for a minute, and just see if it looked badly f'ed up.
seems like the time it takes for a stat blood test is crucial time.
a 1 minute early warning seems like valuable time.

how hairbrained am i?

[SheltieLover]

1. K&R

[MuseRider]

2. LOL a trip down memory lane!

In the later half of the 70's I was a phlebotomist in the lab pre nursing school. I know very little about the actual work of the lab technicians and their machines. We did a test in the rooms in addition to the clotting tests in the lab but I cannot remember what it was called. It was a small lancet that we used to get the blood for a certain type of blotter and did timing of clotting factors. My goodness I cannot even remember what we actually did. It was a round paper that we would let absorb blood so many seconds after the lancet, then again and again until there was no more blood. It was used in addition to the PT and the PTT. At least that is what I remember, in fact I had to learn it by having it done on me and I even have a little scar to remember it by.

I don't know if looking would do much good these days. I suppose they have a tube of blood that does not have a lot of chemicals for the test and the machines they use but eye-balling for clotting factor seems less accurate than even the tests we used to do in the room with the paper and a timer.

[mopinko]

5. well, sure. you wold go ahead and do the test. but time is critical

and a really bad one would stand out, i think.
they still use the same tubes. you can see. the phlebotomists could take a quick look as they set the tubes out for the techs. pull those way off ones, and run them first. there's a couple minutes there.

[ProfessorGAC]

3. What I Read

The reagents being discussed are two types of enzymes (transcriptase & polymerase) and oligonucleotides.
The latter suggests a fairly clear synthesis path, but the enzymes probably require a highly involved extraction process due to the specifity of those reagents.
It's possible to synthesize enzymes, but that's a fairly recent development. At this point I'd guess it very expensive and likely not much large scale production.
Not addressing the med stuff, but the chemistry of the needed materials is something about which I can provide some info.

[mopinko]

6. i was hoping you would pipe up.

what's an oligonucleotide?
i made it through organic, and worked a few labs. i'm sure i can follow.

[ProfessorGAC]

8. How About This?

They're short polymeric nucleotides. Think mini-RNA. The oligo means a various range of chain lengths
Think about corn oil. Triglycerides with various chain lengths. Split the fat, and the fatty acids are the oligomers of the oil. Some are 12 carbons, then 14, 16, 18, some with one or more double bonds.
In this case, the oligomers are the polymerized nucleotides of varying length.

[mopinko]

10. thank you. i just wast familiar w the oligo part.

funny you should say corn oil, as i was thinking margarine.
these dont seem that complex to me. if it's only a matter of patent, it should be waived.

[ProfessorGAC]

12. I Think The Patents Have Long Expired

Partially hydrogenating vegetable oil is 90 year old technology.
Requires expensive hardware, and needs lots of safety systems & interlocks, but is easy & very well understood technology.

[mopinko]

14. you just never know these days. there are patents on

insulin, albuterol, some forms of prednisone. i could go on. which is why this is bugging me.

[dalton99a]

4. Supposedly it's the proprietary ingredients in the extraction buffers used by Qiagen and Roche

A lot of ingredients make up the test for Covid-19. The virus sample obtained from a patient is deactivated, and virus RNA extracted. The main ingredient in the extraction buffer is guanidinium isothiocyanate, although proprietary buffers contain other reagents such as Triton surfactants, says Matthias Trost at Newcastle University. He is leading efforts to expand local testing facilities.

His lab has plenty of the kits, but Trost suggests that many NHS labs – which use liquid handling robots for RNA extraction – will all use the same systems, so it’s possible that delays are caused by supplies of the required buffer running out. ‘Because it’s a proprietary system, it’s not straightforward to change buffers and any replacement needs to be validated.’

The test itself – which makes hundreds of thousands of copies of the virus’s genetic material – is carried out using real time polymerase chain reaction (PCR). It requires two enzymes – reverse transcriptase to synthesise a strand of complementary cDNA from the virus RNA; and a heat-stable DNA polymerase such as Taq polymerase to amplify the DNA, so it can be detected. Enzyme supply doesn’t seem to be an issue. Identifying the virus genetic materials requires primers and probes. These are lab-made fragments of DNA that attach themselves to target sections of the virus-derived cDNA. Marker labels or probes attach to the new copies of the cDNA strands that are made with each cycle of the PCR machine. The probes’ fluorescence can be detected and used to quantify the original amount of viral RNA.

[mopinko]

7. that was my understanding. i think the dpa should allow suspension of such deals.

patents, shit like that, should be wave able by the dpa.
that's why i was wondering about what they actually were.
doesnt sound all that complex to me.

[Ms. Toad]

9. I don't think the issue is identifying the clotting problem

It is addressing it. Nowadays, they also have finger prick PT/INR tests that take seconds.

From personal experience, I can tell you that managing clotting is is far trickier than identifying it. I spend a month in the hospital (well, I was out for two days, the clot got worse, so I was right back in). It took every bit of that time to get me stabilized on heparin, and then shifted to warfarin for home. (That's easier nowadays, too, since the availablity of subcutaneous heparin and the approval for therapeutic use (my doctor talked the insurance company into it in the late 90s, at a time medical dramas were pointing out the idiocy of requiring days or weeks of hospitalization rather than paying (then) about $500 for home treatment.))

From what I understand, some of the meds they are using to treat symptoms influence ablity to clot - and not always in expected ways. So the standard care for clotting, or the lack of ability to clot, doesn't always work as predicted.

[mopinko]

11. interesting.

know a couple of people that had dvt's. yes, it is a tricky thing, and getting it done quickly is essential. glad there is a bedside test. i have some contact w modern medicine, but am amazed on the regular.