Sunday, November 11, 2007

Treponemal Test – TPPA

The Treponema pallidum particle agglutination (TP-PA) test is a treponemal test (confirmation test) for the serologic detection of antibodies to the various species and subspecies of pathogenic Treponema, the causative agents of syphilis, yaws, pinta, bejel, and endemic syphilis. The test is a passive agglutination procedure based on the agglutination of gel particles sensitized with T. pallidum antigens by antibodies found in the patient's serum (1-3). The test is intended as a confirmatory test to replace the microhemagglutination assay for antibodies to T. pallidum (MHA-TP).

Serum containing antibodies to pathogenic treponemes react with gel particles sensitized with sonicated T. pallidum, Nichols strain (the antigen), to form a smooth mat of agglutinated gel particles in the microtiter tray well.

If antibodies are not present, the particles settle to the bottom of the tray well, forming a characteristic compact button of unagglutinated particles.

The unsensitized gel particle control well for each serum should also show this compact button, or the absence of agglutination.

The TPPA test is used to confirm the reactive results of a nontreponemal screening test for syphilis, such as the VDRL slide test, or as a diagnostic test in patients with a nonreactive nontreponemal test but with signs or symptoms suggestive of late syphilis

Interpretation of results
1) Read the settling patterns of the gelatin particles using an angled mirror (tray viewer) to visualize the patterns from below - Readings are scored on a scale of – to 2+ agglutination
2) Retest serum with samples with a reading of ±

Boon Ching

Sunday, November 4, 2007

special stain

Martius scarlet blue (MSB)

Function: stain fibrin

Principle: the main feature of MSB is the use of a small molecule yellow dye, together with phosphotungstic acid to selectively stain red cells. Phosphotungstic acid blocks the staining of muscle, collagen and most connective tissue fibres. Muscle and fibrin are stained with medium size molecule red dye, while staining of collagen is prevented by phosphotungstic acid. Larger blue dye will then stained the collagen and fibrin.

Control: skeletal or cardiac muscle, soft cartilage, fibrinous appendix

Chemical required: 1% acetic acid
2%phosphotungstic acid
martius blue
martius red
martius yellow
weigert iron haematoxylin

Reagent preparation: martius scarlet blue working solution
martius yellow 1 part
martius blue 2 parts
martius red 3 parts

1) dewax, section to water
2) leave slide overnight in zenker’s solution
3) run in water until colourless
4) stain with weigert iron haematoxylin for 10 minutes
5) blue in water
6) stain in martius scarlet blue working solution for 10 mins
7) wash with acetic acid
8) dehydrate, clear, mount

Result: nuclei: blue/black
Erythrocyes: yellow
Fibrin: red
Connective tissue: blue

Wing Fat


For the past two weeks, i am attached to biochemistry laboratory. In this lab, there are quite a number of tests they perform. For example, Urinanalysis, Fungal smear, occult blood, liver function tests, lipid panel and others. Here, in this entry, i will like to discuss about neonatal total bilirubin test and HbA1C.

Neonatal total bilirubin

This test is to screen for and monitor liver disorders, such as jaundice, or liver diseases, such as cirrhosis.

A bilirubinometer which is a direct spectrophotometer is used to measure the total bilirubin in neonatal serum to aid in indicating the risk of bilirubin encephalopathy.

  1. Centrifuge the capillary tube of neonatal blood for 3 minutes at 3000rpm.
  2. By using a pipette, completely fill the cuvette with serum, holding the narrow portion of the cuvette between your thumb and index finger.
    (To avoid erroneous readings, the outside surface of the filled cuvette must clean. The sample seen in the clear rectangular area of the cuvette must be free of bubbles. If bubbles are observed, tap the cuvette lightly to clear them and refill as necessary.)
  3. Open the black door on the top of the instrument and insert the cuvette into the sample carrier until the widest portion of the cuvette is seated. Close the door.
  4. Press the START button. There will be a 2 second delay to allow the lamp to come to equilibrium, after which the sample carrier will rotate to bring the sample cuvette into the optical path. After a short pause, bilirubin concentration will be displayed.
  5. After 15 seconds, the measurement cycle will be complete and the sample carrier will return the sample to the load position. Remove the cuvette.
  6. The display will show the bilirubin value for approximately 10 seconds, then clear.

Once the result is read from the display, we will record it down on the patient’s requisition form and send it for verify.

Interpretation of results

  • Newborns: When bilirubin levels are high, a condition called jaundice occurs, and further testing is needed to determine the cause. Too much bilirubin may result from the rupture of the red blood cells, or that the liver is incapable of removing bilirubin from the blood. It is not uncommon to see high bilirubin levels (sometimes called neonatal bilirubin) in newborn babies (typically 1–3 days old). Within the first 24 hours of life, up to 50% of full-term newborns, and an even greater percentage of pre-term babies, may have high bilirubin level. At birth, the newborn lacks the intestinal bacteria that help process bilirubin. This is not abnormal and resolves itself within a few days. In other instances, newborns’ red blood cells may have been destroyed because of Rhesus blood typing incompatibility.
  • Adults and children: In adults or older children, bilirubin is measured to diagnose and/or monitor liver diseases (such as cirrhosis, hepatitis, or gallstones).


HbA1c is a test that measures the amount of glycosylated hemoglobin in your blood. It is used to measures your blood sugar control over several months and gives a good estimate of how well diabetes is being managed over a period of weeks to months.

Glycosylated hemoglobin (hemoglobin A1c, Hb1c, HbA1c or HgA1c) is a molecule in red blood cells that attaches to glucose (blood sugar). It is a form of hemoglobin used primarily to identify the average plasma glucose concentration over prolonged periods of time. Its name is sometimes abbreviated to A1C. It is formed in a non-enzymatic pathway by hemoglobin's normal exposure to high plasma levels of glucose. Glycation of hemoglobin has been implicated in nephropathy and retinopathy in diabetes mellitus.

Monitoring the HbA1c in diabetic patients may improve treatment.

Normal Results

HbA1c is normal if it is 5% or less. Normal ranges may vary slightly.

Abnormal Results

Abnormal results mean that your blood glucose levels have not been well-regulated over a period of weeks to months. If your HbA1c is above 7%, it means your diabetes is poorly controlled.

That's all for this entry. hope u enjoy reading. =)

Doreen Ng (tg 01)