CHEMILUMINESCENCE IMMUNOASSAY (CLIA)

Chemiluminescence Immunoassay (CLIA) provides a sensitive, high throughput, fully automated immunological technique, which has revolutionized Immunodiagnostics. It measures the intensity of light emitted when the complex of antigen in the patient’s sample and the enzyme linked antibody react with chemiluminescent molecule (such as luminol) producing a weak signal. The enzyme component then provides signal amplification.

ENZYME LINKED IMMUNOSORBENT ASSAY (ELISA)

ELISA is an immunological technique which is used to detect the presence of an antibody or an antigen in a sample. A known amount of antigen is coated on a solid phase like that in the well of a polystyrene microtitre plate and sample containing specific antibodies is added in the wells to allow antigen-antibody binding. The immune complex thus formed is linked to an enzyme, which acts on a substrate to give a coloured reaction which is detected using ultramodern ELISA plate readers. Since ELISA technique utilizes enzyme labels to produce detectable signals, it is given the name Enzyme-Linked Immunosorbent Assay.

HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC)

When molecules in the mixture are very similar, direct quantification becomes difficult. HPLC is a form of column chromatography used frequently to separate, identify and quantify compounds. It consists of a stationary phase that absorbs the analytes and holds them for a particular time. All the molecules in the mixture will spend different time with different stationary phase and then come out at the end. The time that a molecule takes to travel from one end to the other end of stationary phase is known as Retention time. Hence, all the molecules display their own unique retention time for particular stationary-mobile phase combination. Silicagel is most frequently used as the adsorbent which is packed in a column. HPLC columns are densely packed as packing directly affects the resolution. A detector is kept at the end of the column. As the molecules come out from the end, the detector detects and gives a peak on chromatogram. The peak area calculation quantifies the molecule of interest on the basis of standard values.

CAPILLARY ELECTROPHORESIS (CE)

Akin to HPLC, electrophoresis is another emerging technology chaperoning the diagnostic industry. Conventionally, electrophoresis has been utilized for years in the field of research for analysis of genetic material as well as proteins. In the field of diagnostics, this technology has been exploited for analysis of various proteins from blood, serum as well as urine.

ION SELECTIVE ELECTRODE (ISE)

In clinical chemistry, estimation of serum electrolytes is also an essential, as their concentrations affect variety of biological functions. The simple instrumentation and ease of operation makes it again a desirable addition to the lab floor to complete the clinical biochemistry profile.

FLOW CYTOMETRY

Fluorescence flow cytometry is the principle involved in enumerating cell-counts by staining them with fluorescent dyes followed by subsequent detection using laser technology. Flow cytometry involves enumeration of cells based on their physical as well as chemical nature. This technique can enumerate thousands of cells in a minute.

Different fluorescent dyes absorb light at different wavelengths and upon excitation, emit the light at a higher wavelength. This principle is exploited to detect the chemical composition of various cells using the Fluorescence Flow Cytometry method. Thus, multiple dyes are used simultaneously to stain different cells and, with the help of a laser beam using the principle of hydrodynamic focusing, the chemical properties of the cells are studied depending on the stain absorbed by them.

NEPHELOMETRY

Nephelometry is a quantitative method, based on the principle that a dilute suspension of small particles will scatter light (usually a laser) passed through it rather than simply absorbing it. The amount of scatter is determined by collecting the light at an angle.

BIOCHEMISTRY

Biochemistry is the science of measuring visible light and is based on a relationship between absorption of light and the properties of the material through which the light is traveling.

CYTOPATHOLOGY

Cytopathology (sometimes referred to as “cytology”) is a branch of pathology that studies and diagnoses diseases on the cellular level. It is usually used to aid in the diagnosis of cancer, but also helps in the diagnosis of certain infectious diseases and other inflammatory conditions as well as thyroid lesions, diseases involving sterile body cavities (peritoneal, pleural, and cerebrospinal), and a wide range of other body sites. Cytopathology is generally used on samples of free cells or tissue fragments (in contrast to histopathology, which studies whole tissues) and cytopathologic tests are sometimes called smear tests because the samples may be smeared across a glass microscope slide for subsequent staining and microscopic examination. However, cytology samples may be prepared in other ways, including cytocentrifugation.

HISTOPATHOLOGY

Histopathology refers to the microscopic examination of various forms of human tissue. Specifically, in clinical medicine, histopathology refers to the examination of a biopsy or surgical specimen by a pathologist, after the specimen has been processed and histological sections have been placed onto glass slides. This contrasts with the methods of cytopathology, which uses free cells or tissue fragments. Histopathological examination of tissues starts with surgery, biopsy, or autopsy. The tissue is removed from the body of an organism and then placed in a fixative that stabilizes the tissues to prevent decay. The most common fixative is formalin, although frozen section fixing is also common. To see the tissue under a microscope, the sections are stained with one or more pigments. The aim of staining is to reveal cellular components; counterstains are used to provide contrast. Histochemistry refers to the science of using chemical reactions between laboratory chemicals and components within tissue. The histological slides are then interpreted diagnostically and the resulting pathology report describes the histological findings and the opinion of the pathologist. In the case of cancer, this represents the tissue diagnosis required for most treatment protocols.

SURGICAL PATHOLOGY

Surgical pathology is one of the primary areas of practice for most anatomical pathologists. Surgical pathology involves the gross and microscopic examination of surgical specimens, as well as biopsies submitted by surgeons and non-surgeons such as general internists, medical subspecialists, dermatologists, and interventional radiologists. Often an excised tissue sample is the best and most definitive evidence of disease (or lack thereof) in cases where tissue is surgically removed from a patient. These determinations are usually accomplished by a combination of gross (i.e., macroscopic) and histologic (i.e., microscopic) examination of the tissue, and may involve evaluations of molecular properties of the tissue by immunohistochemistry or other laboratory tests.