08 November 2008
12:25:00 AM
I was post to Hb electrophoresis a long time ago and here's an interesting test. Its called the sickle test.
The sickle test is used to demonstrate the sickling phenomenon. I'm sure you guys know about the relationship between sickle cells and malaria right? Patients with sickling tend to be more resistant to malaria as the malaria parasite spends part of its life in RBCs. In normal patients, the parasite would just reproduce and cause malaria. But this wouldnt be a problem as presence of the malaria parasite causes the red blood cell to rupture, making the plasmodium unable to reproduce. Further, the polymerization of Hb affects the ability of the parasite to digest Hb in the first place. Thus, the parasite cannot grow. YEAH!
Guess what, i bet you didnt know that sickle cells are caused by HbS right? Well, now you do.
Here's the principle of the test. Sickling phenomenon occurs with low oxygen tension as HbS has a decreased oxygen affinity. A small drop of blood added to a reducing agent (sodium metabisulphite) to induce sickling in susceptible cells. It is then sealed between slide and cover glass and incubated at 37degrees overnight for the sickling phenomenon to occur. Cool right? We actually just leave it in the oven which doesnt have any light.
So how is it sealed? We used petroleum jelly (the kind people use to lubricate certain areas of their body), and with a glass slide, we slowly apply it on. It requires quite a lot of skill to do a neat job though.
So what are the results we expect? View it under a microscope,if the sample has HbS, it will sickle and if it doesnt contain HbS, it wont. Like duh!
Oh, and we usually prepare 3 samples. 1 negative control from a known patient, 1 positive control from a known patient and our unknown patient sample.
cornelyus
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