Sunday, November 25, 2007

Haematology and LMQA

Name: Dorene

Subject: Haematology
The tests done in the lab are FBC, ESR, blood grouping, coagulation test, haemoglobin electrophoresis. I would like to share with you all haemoglobin electrophoresis test and bloog grouping.

In Haemoglobin electrophoresis, it tests for beta-thalassemia, found most commonly in heteroygous state as beta-thalassemia minor or beta-thalassemia trait. In homozygous state, which is known as beta-thalassemia major, is a lethal disease, as there is no efficiemt treatment for the disease.

Adult blood contains promary haemoglobin A (HbA) and a small percentage of hemoglobin A2, (HbA2) and trace amount of fetal hemoglobin (HbF). For patients with thalassemia, there will be elevated percentage of HbA2 and HbF and this test will determine the quantity of them. The machine used for the test, VARIANT, is a fully automated HPLC (High-performance liquid chromatography) system that can separate and determine area percentages for hemoblogin A2, and F.

Method:

First, pipette 5 microlite of whole blood from patient into separate a 1.5ml vial. Add 1.0ml of hemolysis reagent to each sample vial and mix well to enhance hemolysis effect Finally load them into the machine. For the machine, first press "power" button and let it run on it's own as warm-up. next, press test menu> 1 (1 refers to beta-thalassemia short program). press enter and the test will start running.

Principle of the test:

the machine uses dual wavelength filter photometer at 415 and 690nm to monitor hemoglobin concentration. 415 nm detects the absorbance changed when reagents/buffers are added while 690nm corrects the effects caused by mixing buffers with different ionic strength.

when the test starts, the machine will extract the specimen every ~6 minutes into the analysis stream. elution buffer of different ionic strength will be release each time and pass through the analysis cartridge. the ionic strength of the buffer will be sLlowly increase which cause a higher concentration of hemoglobin to be eluted from the analysis stream. higher ionic strength of the mixture will force more strongly retained hemoglobin to be eluted. Changes in aborbance cause by elution of hemoglobin (difference in absorbance from the start of experiment to the end of experiment) will be detected by the photometer when different ionic strength were added and this absorbance will be converted to absolute values for interpretation.


Interpretation of concentration:

heterozygous beta-thalassemia - HbA2 - 4-9%, HbF - 1-5%
homozygous beta-thalassemia - HbA2 - normal or increased, HbF - 80-100%


Blood grouping

Source:http://www.visualsunlimited.com/browse/vu308/vu308235.html


In the lab, it uses microtiter plate and tile for blood grouping. first one drop of commerical anti A, B, AB, D are added into consecutive well (G F E D) respective. one drop of A B and O are then added into well (C B A). The lab number of the specimen are then written on the plate. next, the spin down the specimen to separate serum from the red cells. One drop of serum are then added each into well C B A, containing A, B, O blood cells. next dilute the rbc in saline to have 3-5% concentration. and one drop of it will be added each into well G F E D containing anti A,B,AB,D. mix the blood using a vibrator and centrifudge it at 900rpm for 1.5min to concentrate the agglutins.

Results : agglutination = positive. no agglutination = negative.


Quality Hierarchy Model in LMQA

In LMQA, it teaches us about quality control, quality assurance, quality system, quality management and total quality mangement. In our lab, i noticed there is also such system and would like to share about it more with you all.

1. Quality Control - eg:Quality controls are performed in all machines by technicans and documented down everyday.

2.Quality Assurance - eg: Quality of all reagents, plates, equipment are checked and approved upon arrival before using by supervisior and technicans. Having external QC to ensure precision and accuracy.

3.Quality System -eg: work on areas to improve efficiency and quality of the system.

4.Quality Management - eg: having meeting every week for management level to work on the problems encountered and determine ways of troubleshooting. Work on areas to improve efficiency and quality of the system.

5. Total quality management - eg:development of lab automation in the laboratory(it's half automated currently), upgrade of the device and standards of the laboratory.

Wednesday, November 21, 2007

reply questions

sorry for the late reply caz busy with the MP.

1.What's the clinical significance of the PYR test and what does PYR stand for? June
The clinical significant of PYR test is to help microbiologist to detect the pyroglutamate aminopeptidase found in group A streptococci (Streptococcus pyogenes) and group D enterococci. PYR stands for pyrrolidonyarylamidase

2. What do I expect to see after the developing soultion is added onto the test area if the specimen is negative for PYRase activity? Eugene Wong
A negative test is indicated by no color change.

3. "PYR test kit uses Test Cards impregnated with L-pyroglutamic acid 7-amino-4-methyl-coumarin (7AMC) and dimethylamino-cinnamaldehyde for the detection of PYRase activity."how does L-pyroglutamic acid 7-amino-4-methyl-coumarin (7AMC) and dimethylamino-cinnamaldehyde aid in the detection of PYRase activity?"The enzymatic hydrolysis of this substrate by enterococci, Group A streptococci and Citrobacter spp. produces a purple colour followed by the addition of the Developing Solution."enzymatic hydrolysis of what? L-pyroglutamic acid 7-amino-4-methyl-coumarin (7AMC) and dimethylamino-cinnamaldehyde to give purple colour? Cass

Some Enzyme in Group A streptococci and Citrobacter spp can hydrolysis the L-pyroglutamic acid 7-amino-4-methyl-coumarin (7AMC) and dimethylamino-cinnamaldehyde, they react together to give a purple color.

4. can u explain what is PYRase activity? Juexiu
PYRase activity means the ability of the bacteria to product PYRase.


Liu Qian
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