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Fluorescin In Situ Hybridization (FISH)

January 21, 2012 By Leave a Comment

Fluorescence in situ hybridization is a cytogenetic technique that is used to detect and localize the presence or absence of specific DNA sequences on chromosomes.

FISH uses fluorescent probes that bind to only those parts of the chromosome with which they show a high degree of sequence complementarity.

Fluorescence microscopy can be used to find out where the fluorescent probe bound to the chromosomes.

Uses

Fluorescence in situ hybridization  is used in genetic counselling, medicine, and species identification.

It can also be used to detect and localize specific mRNAs within tissue samples and thus identify organisms  which otherwise are not identifiable on routine tests.

 

Further resources on FISH

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Enzyme linked Immuno Sorbent Assay (ELISA)

January 20, 2012 By Leave a Comment

All microbial species have one antigen which is unique. These antigens can be purified and used to generate specific monoclonal antibodies.
Both the things, antigen and antibodies provide a highly specific diagnostic tool.

The term ELISA stands for enzyme linked immunosorbent assay is a serological test to look for presence of particular antigen or antibody.

There are two types of assays in ELISA

Direct

Direct ELISA uses monoclonal antibodies to detect the antigen. [Read more...]

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Filed Under: Basics, Musculoskeletal Infections Tagged With: , ,

Polymerase chain reaction (PCR)

January 20, 2012 By 1 Comment

The polymerase chain reaction (PCR) is a technique in molecular biology to amplify a single or a few copies of a piece of DNA to produce thousands to millions of copies of a particular DNA sequence within short time.

The technique was developed in 1983 by Kary Mullis.

A typical PCR involves 20-40 repeated temperature changes, called cycles, with each cycle commonly consisting of 2-3 discrete temperature steps.

Initialization step

This step consists of heating the reaction to a temperature of 94–96 °C . It is required for activation of DNA polymerase.

Denaturation Steps

 

This step consists of heating the reaction to 94–98 °C for 20–30 seconds. It causes DNA melting of the DNA template . [Read more...]

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Palmar Tilt of Distal Radius

December 15, 2011 By 1 Comment

Palmar Tilt represents the angle between a line joining the dorsal and volar margins of the articular surface and the long axis of the radius on a lateral xray.

Palmar TIlt of Distal Radius

Palmar TIlt of Distal Radius

It is also called Volar Angle or Radial Tilt.

The normal palmar tilt averages 11° and has a range of 2°-20°.

It is an important parameter in treatment of distal radius fractures.

Image Credit
http://www.radiologyassistant.nl/en/476a23436683b

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Filed Under: Basics, Definitions, I-M, Musculoskeletal Radiology, Wrist Injuries Tagged With: , , , ,

C Reactive Protein

December 2, 2011 By Leave a Comment

C-reactive protein (CRP) is a protein found in the blood which rises in level in response to inflammation.

CRP was first discovered as a substance in the serum of patients with acute inflammation that reacted with the C- (capsular) polysaccharide of pneumococcus and thus the name.

It was discovered by Tillett and Francis in 1930 and is synthesized in liver.

 

A rise in CRP occurs as acute phase response  in a wide range of conditions like infections, inflammatory diseases, malignancy and autoimmune disordres. The levels of CRP rapidly increase within 2 hours of acute insult, reaching a peak at 48 hours. [Read more...]

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What Is Erythrocyte Sedimentation Rate or ESR

December 2, 2011 By 1 Comment

The erythrocyte sedimentation rate (ESR), also called a sedimentation rate or Biernacki Reaction, [The test was invented by the Polish doctor Edmund Biernacki] is a common test in hematology [A branch of pathology dealing in blood investigations] and measures the rate at which red blood cells sediment in a period of 1 hour.

The erythrocyte sedimentation rate (is a nonspecific because increased results do not tell the doctor exactly where the inflammation is in the body or what is causing it, and also because it can be affected by other conditions besides inflammation.

For this reason, the ESR is typically used in conjunction with other tests. [Read more...]

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Blood Supply of Neck Of Femur

October 9, 2011 By Leave a Comment

Blood supply of proximal part of the femur is derived from following sources

Retinacular Vessels

Ascending cervical vessels arise from the extracapsular ring of anastomosis formed by the medial and lateral circumflex femoral artery at base of neck. Ascending Cervical Branches travel proximally under the hip capsule and continue proximally along neck deep to synovial membrane
toward the femoral head.

These arteries are known as retinacular arteries and are divided into three groups [Read more...]

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Filed Under: Basics, Hip Fractures

What Are Different Types of Wounds [Classification of Wounds]

September 14, 2011 By Leave a Comment

Wounds can be classified according to

  • Thickness of the wound
  • Involvement other structures
  • Time since injury
  • Morphology.

Different Types of Wounds Depending On Thickness of the Wound

  • Superficial wounds – Involve the epidermis and the dermis up to the dermal papillae
  • Partial-thickness wounds – Involves skin loss up to the lower dermis [Part of the skin remains, shafts of hair follicles and sweat glands are left]
  • Full-thickness wounds – Involves the skin and the subcutaneous tissue [Tissue loss occurs, and the skin edges are spaced out]
  • Deep wounds – These also include complicated wounds like with laceration of blood vessels and nerves, wounds penetrating into natural cavities, and wounds penetrating into an organ or tissue

Different Types of Wounds Depending On Involvement of other structures

  • Simple wounds, comprising only 1 organ or tissue
  • Combined wounds (Mixed tissue involvement)

[Read more...]

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Various Types Of Bone Graft Based On Grafting Technique

April 30, 2010 By 5 Comments

Single Onlay Cortical Grafts

The term onlay graft was coined by Campbell. The technique involves a bone graft in which the transplanted tissue is laid directly onto the surface of the recipient bone. The technique is more of historical importance. The technique is rarely used now.

Dual Onlay Graft

This was devised by Boyd. Two cortical onlay grafts are placed opposite each other on the host bone across the nonunion and are fixed with the same set of screws; they grip the fragments like a vise. Any intervening space at the bone ends is filled with cancellous chips.

Dual grafts also have been used for other nonunions and rarely done now. [Read more...]

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Different Types of Bone Grafts

March 30, 2010 By Leave a Comment

Autogenous Grafts

Also called autograft. This graft comes from patient’s own body.The grafts usually are removed from the tibia, fibula, or ilium. These three bones provide cortical grafts, whole bone transplants, and cancellous bone.

Disadvantages to the use of the tibia as a donor area include the following:

  • Morbidity of the patient is increased.
  • Removal of the graft adds to the duration and magnitude of the procedure.

For these reasons, structural autografts from the tibia are now rarely used. [Read more...]

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