Molecular pathology. Definition . Molecular pathology is the study and diagnosis of disease through the examination of molecules within organs, tissues or bodily fluids.
It is multi-disciplinary in nature and focuses mainly on the sub-microscopic aspects of disease.
Human H5N1 disease is clinically and pathologically distinct from that caused by seasonal human influenza A H3N2 or H1N1 viruses.
Reactive hemophagocytosis in multiple organs, and occasional detection of viral antigen or viral RNA in extrapulmonary organs suggest a broader tissue distribution of H5N1 viruses compared with seasonal viruses in fatal human cases.
The elevation of plasma cytokine levels was positively correlated with pharyngeal viral load and may simply reflect more extensive viral replication.
use of different techniques to detect virus distribution and infection of 5 organ systems in a laboratory confirmed fatal human H5N1 virus infection, and analyze the relationship between viral load in tissues and host response.
live virus was recovered from respiratory tissues including lung, trachea, bronchus and aortopulmonary vessel. In the digestive system, virus was isolated from tissues collected from the ileum, colon and rectum, but not the stomach, duodenum or liver.
The tissue distribution of viral RNA or antigen detected by ISH and IHC stains respectively, was also generally consistent with virus isolation by culture or real time RT-PCR result.
Immunohistochemistry or IHC refers to the process of detecting antigens (e.g., proteins) in cells of a tissue section by exploiting the principle of antibodies binding specifically to antigens in biological tissues.
IHC takes its name from the roots "immuno," in reference to antibodies used in the procedure, and "histo," meaning tissue compare to immunocytochemistry
Immunocytochemistry is performed on samples of intact cells that have had most, if not all, of their surrounding extracellular matrix removed. This includes cells grown within a culture, deposited from suspension, or taken from a smear.
Because of the method of fixation and tissue preservation, the sample may require additional steps to make the epitopes available for antibody binding, including deparaffinization and antigen retrieval.
the samples are incubated with a buffer that blocks the non specific reactive sites to which the primary or secondary antibodies may otherwise bind
Fresh unfixed, fixed, or formalin fixation and paraffin embedding
3.Whole Mount Preparation
It is to test for a protocol or procedure used.
It will be ideal to use the tissue of known positive as a control.(known tissue)
It is to test for the specificity of the antibody involved.(non-immune serum)
1. The Procedure needs the expertise of the technician as well as the pathologist
2. Certain markers initially thoughts to be specific for certain tissues or tumors have proved to be shared by several other tissues and other neoplasm,eg S 100.
a. Loss of antigen through autolysis
b. A scanty amount of tissue
c. Extensive necrosis of the tumour
d. Inappropriate, de natured antibody
4. False positive result may be due to:
a. Cross- reactivity of antibodies with other antigens
b. The presence of endogenous peroxidase
c. Entrapment of normal tissue by tumour cells
Fluorescent DNA ISH (FISH) can, for example, be used in medical diagnostics to assess chromosomal integrity