Okay, so I have learnt about TDx/IMX. Basically, TDx/IMX are the name of analyzers that help to detect therapeutic dosage of drugs so as to ensure appropriate therapy for patients.
Firstly, I am going to talk about TDx analyzer. This analyzer utilizes Fluorescence Polarization Immunoassay (FPIA) technology. Briefly, this FPIA employs the antigen (patient's sample), antigen (labeled with fluorophore) and antibody reaction. When there is low concentration of antigens in patient's sample, more labeled antigens will bind to the antibodies, thus polarization increase. However, high concentration of antigens in patient's sample will cause less labeled antigens to bind to the antibodies, thus polarization decrease.
TDx analyzes drugs such as cyclosporine, methotrexate and everolimus. Cyclosporine and everolimus are immunosuppresant drugs whereas methotrexate is an antineoplastic drug.
For IMX, it utilizes Microparticles Enzyme Immunoassay (MEIA) technology. This MEIA employs the sandwich principle which involve antigens (patient's sample), antibodies and antibodies ( labeled with alkaine phosphatase). The antigens will bind to antibodies bound on microparticles, forming immune complexes. The labeled antibodies will then bind to the immune complexes and catalyzes the substrates added. The catalytic reaction will generate a fluorescent product and this product is measured.
IMX analyzes drugs such as tacrolimus, sacrolimus and also squamous cell carcinoma (SCC) antigens. Tacrolimus and sacrolimus are immunosuppresive drugs whereas SCC antigens are found on squamous cell cancer tissue on the uterine cervix.
These are the tests that I have done: Cyclosporine test, methotrexate test, tacrolimus test and everolimus test. The procedure are as follows:
- Labeled microcentrifuge tubes for each patient's sample accordingly.
- 150 uL of patient's sample is pipetted into the corresponding tubes.
- 50 uL of solubilization reagent is then added to the tubes.
- Each tubes are vortexed for 10s to ensure thorough mixing (make sure caps are tight)
- Sample tubes are centrifuged for 5min at 10800rpm so as to obtain the supernatant.
- Supernatant is decanted into corresponding sample cells on the carousel.
- Reagent pack is mixed gently.
- The reagent pack and the carousel are placed on the analyzer and samples are run.
- Results are obtained and recorded.
This is the link if you want to see how the analyzer looks like:
Hi. Erm from what you had mention in your post,
ReplyDeleteif there is high amount of antigens in patients samples the polarisation will increase and if the amount of antigens in patient sample is low.polarisaion will decrease. So the purpose for the increase or decrease in polarisation is only to quantitate the amount of antigens in the sample?
Jennifer(TG02)
Hi
ReplyDeleteMay I know how does measuring the concentration of the antigen in the patient sample and obtaining the level of polarization help to ensure appropriate therapy for the patient?
0703827F
Liyana
hello siti,
ReplyDeletethanks for sharing.
regarding your post, you mention that when there is a low concentration of antigens in the patients serum, more labelled antigens will bind to the antibodies, so the antigen youre refering to is ?
and also, how the results will help in appropriate drug therapy for the patients?
thanks,
kenneth
tg02
YEOOO SHAHIMAHHHHHHHHHHHHHHHHH! :D
ReplyDeletewhy there is low conc of antigen den more labelled antigen will bind to antibodies? is it something like competitive binding?
MERCI BUGU. (i duno how to spell lah, HAHAHA)
Joanna Yeo!
0702054H
hi, for the patient's samples,
ReplyDeletedo you use the patient's serum or the red cell? can i also know what is the advantages and disadvantages of the 2 machines? is it correct to say that TDx has a higher chance of error, as the antibody could still have a chance to bind the the labelled antigen instead of the antigen in the patient's sample?
i also do not understand how does the machines determine how much dose of the drug to give to the patients since TDx doesn't seem to be able to quantify. does it mean the lesser antigens bound (lesser fluorescence) means that the patient is on the road to recovery?
LIM JIA HUI JOEY
0703605F TG01 GROUP2
hey jenniffer.
ReplyDeleteactually when there is LOW concentration of antigens in patient's sample, MORE labeled antigens will bind to the antibodies, thus polarization INCREASE. However, HIGH concentration of antigens in patient's sample will cause LESS labeled antigens to bind to the antibodies, thus polarization DECREASE.
Yes, the purpose of this assay is to provide a quantitave measurement of the drugs.
siti :)
hey joaannnnaa!!!
ReplyDeleteyes. the assay employs 2 technologies i.e competitive binding and fluorescence polarization.
siti :)
its merci beaucoup!..hahaha
Very good. The key purpose is to quantify the drug level present in the patient's blood. Thus, the drug is the antigen and the immunoassay (MEIA or FPIA) is the methodology used. Each drug quantification has a specific reagent kit used for in the machine (TDX). Each reagent kit will have the specific antibodies to capture only the type of drug that you are interested to quantify.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteto kenneth, the antigen that im referring to is the drug antigen.
ReplyDeleteto liyana and kenneth,when the results are obtained, the doctors will verify them and ensure appropriate treatment is given to the patients by increasing or decreasing the drug dose. Due to the complexity state and differences in individual's response to certain drugs, different individuals have different requirements for optimal blood level of the drugs. Each patient should be thoroughly evaluated clinically before the doctors amend the treatment regimen. In addition, the patient should established his/her drug range of concentration based on clinical experiences.
Therefore, when the result show a high result, the doctors would decrease the drug concentration in the subsequent treatment. On the other hand, when the result show a low result, the doctors would increase the drug concentration in the subsequent treatment and also monitor the drug level so as to prevent toxicity.
siti:)
Hey joey!
ReplyDelete1.We use the patient's serum for the assay.
2.Advantage of TDx is that it can test for therapeutic drugs as well as additional tests (e.g. endocrine function, hormones, toxicology, abused drugs and immunosupressants) allowing consolidation of testing on one automated analyzer. On the other hand, advantage of IMx is that the analyzer is able to utilizes combination of MEIA and FPIA which allows both high and low molecular weight analytes to be measured. In addition, IMx offers a wide range of tests e.g. cancer markers, cardiac markers and hepatitis, so to name a few. For the disadvantages, I don't think there are any significant. However, there are some limitations of procedure such as both of these immunoassays can cross-react with the drug metabolites and thus overestimate that particular drug concentration. In addition, patients who received mouse monoclonal antibodies for diagnosis or therapy may contain human-anti mouse monoclonal antibodies (HAMA). The immunoassays are able to utilize these HAMA, thus resulting either false positive or negative results.
I don't think TDx has a higher chance of error. FPIA also employs competitive binding technology. Therefore high concentration of antigens in patient's sample will prevent labeled antigens to bind to the antibodies and vice versa.
3.TDx only provides a quantitative measurement. When lesser labeled antigens bound (lesser fluorescence), it does not means that the patient is on the road to recovery. It means that more drug antigens are bound, indicating that there is high concentration of drug in the patient.Different individuals have different requirements for optimal drug level in the blood and the individuals should have established his/her range of the drug concentration based on past clinical experiences. So, the doctors would know if the treatment regimen for the individual should be amended or not.
siti :)