TDx/IMX

Hey. Siti Shahimah is here again. :)

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:

1. Labeled microcentrifuge tubes for each patient's sample accordingly.
2. 150 uL of patient's sample is pipetted into the corresponding tubes.
3. 50 uL of solubilization reagent is then added to the tubes.
4. Each tubes are vortexed for 10s to ensure thorough mixing (make sure caps are tight)
5. Sample tubes are centrifuged for 5min at 10800rpm so as to obtain the supernatant.
6. Supernatant is decanted into corresponding sample cells on the carousel.
7. Reagent pack is mixed gently.
8. The reagent pack and the carousel are placed on the analyzer and samples are run.
9. Results are obtained and recorded.

This is the link if you want to see how the analyzer looks like:

1. http://www.gmi-inc.com/CliniLab/tdxflx.html
2. http://www.labequip.com/itemcatalog/stkno/23546/Abbott-Laboratories-IMX/-Blood-Chemistry-Analyzer.html

urinalysis

hii it's my turn now !
so, i'll be writing about the department i was allocated last week, urinalysis. before i start on the processes of tests done by this bench, there are some preparations and QCs to mention briefly. this is also what we usually do to start off the exciting day. after rollcall, i'll be preparing the 0.1% hypochlorite. pretty easy as they're in the tablet form. only thing to note is- how many tablets to how much DI water. for QC, we have to do it for the osmometer, refractometer, ABG analyzer and the dipstix analyzer. materials used for these QCs are mainly DI water, saline and commercial solution.
okay, so now i'll begin on the tests/skills i've learnt.
1. urine FEME
this test includes both dipstix and microscopic examination (ME). we should be familiar with the procedures for this test thus i'll summarize what i've learnt. there is a correlation between the dipstix result and the ME.
if there is a presence of protein, there could be casts present under the ME. similarly, positive nitrate shows presence of microorganism, positive esterase shows presence of WBCs.
2. rapid plasma reagin (RPR) card test
to test for syphilis using the patient's serum. we use a kit, Omega Diagnostics Immutrep RPR to carry out this test with only one drop of serum. there is a positive and negative control to compare with the samples. positive results will show agglutination.
3. dengue panel
this test is also carried out by using a commercial kit, SD Dengue Duo, a one step dengue NS1 Ag and IgG/IgM test. time taken is around 15 minutes.
4. arterial blood gas (ABG)
ABG!! that's what the order entry person shouts after they have ordered this test. reason being, it must be done asap to obtain an accurate result as this test measures the pH and the partial pressure of oxygen, carbon dioxide and also, bicarbonate concentration of the blood sample. the analyzer used is called Roche OMNI C. just have to poke the needle into the syringe and the analyzer produce the results. so, it is pretty simple. however, most of the time the med tech will be doing this as their pass are needed to operate this analyzer. i've tried it couple of times tho. ;)
5. HCG test
there is a test kit for this too and patient's serum is used. altho urine can also be loaded on the kit, serum is preferred as it gives a more accurate result. it's a straightforward test with either a +/- shown after 15 minutes.

ps i have photos to upload but dontknow how :s will add in after figuring out.

enjoy weekends,
wendyong

Week 4

Hello Everyone!
I’m Nyzah.

For the first two weeks of SIP, I’m attached to the central processing (CP) are whereby specimens were sorted out, processed and ordered. Specimens usually will arrive in the pneumatic tube via the pneumatic system. The pneumatic system connects all wards, specialist clinics and operating theatre. Sometimes, the healthcare workers will also dispatched the specimens to the clinical lab personally. This is done by passing it through a window. Medical technologist will then attend to the specimens.

The specimens are then processed by removing the request forms from the kangaroo pouch and stapling it to the Ziploc bag with the specimen in it. Specimens ranging from plain tube, EDTA tube, fluoride tubes, urine samples, stools and blood gas specimens are processed there. For microbiology specimens, the specimens are placed inside a red plastic box and for histopathology specimens into the green plastic box. This is because microbiology laboratory is out of bound due to the H1N1 cases and histopathology due to renovations. The other specimens are then placed on the CP workstations whereby the medical technologists or the laboratory clerk will order the tests wanted in the Laboratory Information System (LIS). Then, specimens that come in tubes (usually blood) are removed from the Ziploc bags. Barcode are pasted on it and the details of the patients are pasted on the workstation forms. For other specimens other than tubes, the barcodes are pasted on the Ziploc bags. The person pasting the barcodes have the responsibility of checking the names and the I/C number of the patient against the labeled tubes or other samples. The specimens are then dispatched to various workstation i.e. hematology, biochemistry, etc.

If the person is unsure about the tests that are need to be done, it is necessary for them to call the doctor or the staff nurse in charge so as to avoid confusion and long turnaround time.

Nurul Nyzah
0702888I

Third Week - Rabbit's blood collection

Done by: Eriko
Section: Haematology

YohOoo! So, last week I did blood collection from rabbits.

Firstly, to prevent the rabbit from moving as much, it is wrapped around with towel with only the head and ear exposing. Then, its ear is cleaned with alcohol swab to disinfect that area for blood collection. A needle is then injected into the central auricular artery. When this step is performing and the rabbit moves, the needle is removed immediately and the processes have to be repeated. Sometimes, we have to massage the other ear to distract the rabbits so as they don't shake/move when we are injecting with the needle.

Then, a syringe is connected to the needle to draw the blood. When the desired amount of blood is drawn, gauze is placed on top of the injected area to apply pressure so as to stop the bleeding. Blood is then injected to EDTA tube and inverted a few times to prevent blood clot.

However, during the blood collection, the blood will always clot. Thus, a pre-rinsed anti-coagulant syringe is preferred to be used in this case.

Here's a picture of blood collection from rabbit to help you picture it better:)


Retrieved on 6 July, 2009 from website media.wiley.com

That's it, guys!

Good luck and enjoy your SIP!~~~~

xo

Clinical Chemistry - DP analyzer

Hey, here's Natasha:]

I am attached to a clinical chemistry lab for my SIP. There are a number of workstations consisting of different analyzers in this clinical chemistry lab. For the first week, I am assigned to the Modular Analytics Evo DP analyzer.

This DP analyzer can be divided into three sections; D module, P module and ISE module.

The D and P modules of the DP analyzer actually performs photometric assays on serum/plasma, urine and CSF samples. It measures the absorbancies of the chemical reaction in the reaction cells when the sample is mixed with the appropriate reagent. The D module performs several tests such as renal function test (urea, creatinine, etc), liver function test (AST, ALP, etc) and lipids (total cholesterol, triglycerides, etc). The P module can actually perform tests similar to the D module; however in this clinical lab, it is used to conduct the diabetic panel test (glucose) only. The only difference between the D and P modules is the method used to add the reagents into the reaction cells. The D module stands for 'dispensing' so it will dispense the reagents into the reaction cells. The P module stands for ' pipetting' so it will pipette the reagent from the reagent bottle and then release it into the reaction cells.

The ISE module, however, invloves measuring the difference in electircal potential between the sample measurement electrode and the reference electrode. The electrical poential of the KCl reference solution on the reference electrode serves as a zero baseline for the ISE calculations of the samples. The ISE module is used to determine the amount of sodium, potassium and chloride in the samples.

One of the tests that could be performed on the DP analyzer (specfically P module) is the glucose tolerance test (GTT). GTT is actually the dministration of glucose to determine how quickly glucose is cleared from the bood of the patient. The test is usually used to test for diabetes and insulin resistance in those patients.

Glucose is the major monosaccharides present in the blood and serves as an esential energy supplying substrate for cellular functions Glucose degradation occurs via glycolysis. Glucose determinations can be used in detecting hypoglycaemia and hyperglycaemia, in the diagnosis of diabetes as well as in the monitoring of glucose levels in people with diabetes.

The patient sample is taken in the form of blood in sodium fluoride/ potassium oxalate tubes (grey tubes). Sodium fluoride is an anti-glycolytic agent which aids in inhibitng glycolysis. The patient would have to fast the night before the test. For the test, the patient would have to drink a liquid containing a certain amount of glucose. Then after 2 hours, the patient's blood will betaken again. Thus there will be two grey tubes; one containing patient blood at 0 hours before the intake of glucose drink and the other containing patient blood at 2 hours after the intake of glucose drink.

In a person without diabetes, the glucose levels will rise and then fall rapidly. However in a person with diabetes, glucose levels will rise higher than normal and fail to come back down as fast.