Tuesday, May 24, 2016

Cardiac Troponin I (cTnI) assay by immunochromatography method: Principle, Procedure, Interpretation and results

Rapid Assay for detection of Human Cardiac Troponin I (cTnl) in Serum/Plasma & Whole Blood by ImmunoChromatography

Fig. Troponin I kit showing Positive result
This test utilizes the principle of immunochromatography, with a unique two-site sandwich immunoassay on a nitrocellulose membrane. The conjugate pad contains two components - monoclonal anti-cTnl conjugated to colloidal gold and rabbit IgG conjugated to colloidal gold. As the test sample flows through the membrane assembly of the device, the highly specific anti-cTnl antibody - colloidal gold conjugate complexes with cTnl in the sample and travels on the membrane due to capillary action along with rabbit IgG-colloidal gold conjugate. This sample moves further on the membrane to the test region (T) where it is immobilized by another specific anti-cTnl antibody coated on the membrane leading to the formation of a pink-purple band. A detectable colored band is formed if cTnl level is equal to or greater  than 0.1 ng/ml. The absence of this colored band in the test region indicates cTnl concentration < 0.1 ng/ml.

Sunday, February 28, 2016

BCR/ABL1 Testing: Introduction, indications, methods and interpretation

Fig. BCR-ABL1 fusion gene (Philadelphia chromosome)
BCR-ABL1 refers to a gene sequence found in an abnormal chromosome 22 of some people with certain forms of leukemia. Unlike most cancers, the cause of chronic myelogenous leukemia (CML) and some other leukemias can be traced to a single, specific genetic abnormality in one chromosome. The presence of the gene sequence known as BCR-ABL1 confirms the diagnosis of CML and a form of acute lymphoblastic lymphoma (ALL). Chronic myelogenous leukemia (CML) is part of a group of diseases called the myeloproliferative disorders, with an estimated 4600 newly diagnosed cases and 850 deaths in 2005. More than 95% of patients with CML have the distinctive Philadelphia chromosome (Ph1) that results from a reciprocal translocation between the long arms of

Tuesday, January 26, 2016

Zika virus : epidemiology, symptoms, diagnosis, treatment and prevention

What is Zika Virus ?

Zika virus falls under member of Flavivirus.  The vector for Zika vius is Aedes mosquito. Zika virus is an emerging mosquito-borne virus that was first isolated in Zika forest of Uganda in 1947. Since then, it has been observed mainly in Africa, with small and sporadic outbreaks in Asia.
Fig. Zika virus is transmitted by daytime mosquitoes
under the genus Aedes.
Credit: Photo from Wikipedia

Where has Zika virus been found?

·  Prior to 2015, Zika virus outbreaks have occurred in areas of Africa, Southeast Asia, and the Pacific Islands.
·   In May 2015, the Pan American Health Organization (PAHO) issued an alert regarding the first confirmed Zika virus infections in Brazil.
·   Currently, outbreaks are occurring in many countries.
·         Zika virus will continue to spread and it will be difficult to determine how the virus will spread over time.

Monday, December 21, 2015

Photometry: Principle, applications and types


Fig. Principle of colorimetry
When light is passed through a coloured solution, certain wavelengths are selectively absorbed giving a plot of the absorption spectrum of the compound in solution. The wavelength at which maximum absorption is called the absorption maximum (λmax) of that compound. The light that is not absorbed is transmitted through the solution and gives the solution its colour.

Photometric instruments measure transmittance, which is defined as follows:

                               Intensity of the emergent (or transmitted) light         Ie
Transmittance (T)= ------------------------------------------------------------- = ------
                                               Intensity of the incident light                    Io

Transmittance is usually expressed on a range of 0 to 100%.

If the concentration of the substance in solution is increased linearly, or if the path length that the light beam has to traverse is increased, transmittance falls exponentially. So a term absorbance is defined so that it is directly proportional to the concentration of the substance.

Absorbance (A)= log1/T = log  ----

Absorbance has no units. Photometric instruments electronically convert the measured transmittance to absorbance values.

Sunday, December 20, 2015

Cerebrospinal fluid (CSF) : Formation, composition, function, pathological state and biochemical analysis

A. Formation

Cerebrospinal fluid (CSF) is a clear, colourless fluid filling the ventricles and subarachnoid space. CSF production is a result of the combined processes of diffusion, pinocytosis and active transfer. The majority is produced by selective dialysis of blood plasma by a specialized sponge-like structure called the "choroid plexus" of third, lateral and fourth ventricles.

Fig. CSF collection
The anatomy of the ventricular system allows for movement of CSF in and around all the major structures of the brain. From the lateral ventricles located within the cerebral hemisphere, it circulates through the foramina of Monro into the third ventricle. At its caudal end, the third ventricle is connected by aqueduct of Sylvius to the fourth ventricle. CSF then flows into the basal cisterns and subarachnoid space by two lateral foramina of Lusckha and median foramina of Magendie. From the cisterns the CSF flows / throughout the subarachnoid space and over the hemispheric convexities and around the spinal cord.

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