SEMINAR
TOPIC: TRANSPLANTATION
Transplantation Is The Technique Of Transferring Cells , Tissues
, Or Organs From One Site To Another Or From A Donor To A Recipient . It Is An
Alternative Treatment For A Variety Of Otherwise Fatal Conditions . The
Accounts Of Early Transplants Deal With Skin Transplantation . The First
Reasonable Account On Transplantation Is Of The Indian Surgeon Sushruta In
Second Century Bc , Who Used Auto grafted Skin Transplantation In Nose
Reconstruction . The First Systematic Study Of Transplantation was Reported In
1908 By Alexis Carrel , Who Interchanged The Kidneys In A Series Of Nine Cats ,
Some Of Which Could Survive For Up to 25 Days .
Major Steps In Skin Transplantation Occurred During World Wars First And
Second . The Successful Human Kidney Transplantation Was Carried Out In Boston
In 1954 . Since Then , A Steady Improvement In The Perfection Of Organ
Transplantation Technique Has Been Achieved . Now , Transplantation Of Organs
And Tissues Is A Common Medical Practice . The Transplantation Of Many
Different Tissues Or Organs Including Kidneys , Heart , Pancreas , Lungs ,
Liver , Bone Marrow , Cornea Is Undertaken With Increased Success Rate .
Tissue And Organ Transplantation
1)
Corneal Graft
Corneal Grafts Constitute Some Of The Most Successful Grafts
Done To Date. This Is Because They Are Avascular And Do Not Sensitize The
Patient . They Survive Without Immunosuppressive Therapy . Grafts Of Cartilage
Are Successful In The Same Way And Remain Protected By The Matrix . Such
Tissues Are Referred To As Immunologically Privileged Sites ; Due To Their
Poor Accessibility With Regard To The
Immune System.
2)
Kidney Transplants
Kidney Transplantation Was First Successful Transplantation
Performed At Peter Bent Brigham Hospital In 1954 . Since Then , Thousands Of
Successful Kidney Transplants Have Been Carried Out And Survival Rates Are High
. Advances In Tissue Typing And Improved Understanding Of Immunosupressive
Therapy , Especially Cyclo Sporine , Has Contributed To The Success Of Renal
Transplants . It Has Now Been Firmly Established That Multiple Blood
Transfusion Prior To Grafting , Aids Survival Of The Graft .
3)Heart Transplants
The First Successful Human Heart Allograft Was Performed In 1967
. Cardiac Transplants Are Indicated In Patient Aged 40 Or Below With End Stage
Of Coronary Artery Diseases , Cardio Myopathy , Rheumatic Heart Disease Or
Congenital Heart Disease . Absolute Contra Indication Are Severe Pulmonary
Hypertension , Infection And Cancer . The One Year Survival Rate For Heart
Transplants Stands At Around 80 % Mainly Due To The Introduction Of
Cyclosporine . Full HLA Matching , Though Ideal , Is Not Possible .
4) Liver Transplantation
The Most Common Indication For Adult Liver Transplantation Has
Been Hepatitis B antigen Negative , Post Necrotic Cirrhosis Or Chronic
Active Hepatitis . Infants And Children With Congenital Or Developmental
Anomalies Of The Bile Duct , Benefit From Successful Liver Transplants . Other
Indications For Liver Replacement In Children Inborn Errors Of Metabolism Such
As Wilson’s Disease . The Survival Rate For One Year Is 68% For Adult And 75%
For Children .
Over The Past Two Decades , Allogeneic Bone Marrow
Transplantation Has Evolved From An Experimental Procedure Reserved For
Patients With Refractory Leukemia Into A Rapidly Expanding Are Of Clinical
Investigation That Offers Potential Cure For Patient With Aplastic Anemia ,
Acute And Chronic Leukemia , Breast Cancer , And Selected Types Of Lymphoma .
Classification Of Transplants
Immunologist Have Developed A Special Vocabulary To Describe The
Kinds Of Cell And Tissues Met With During Transplantation . In Transplantation
, The Organ Or Tissue That Is Being
Transplanted Is Called A Transplant Or Graft . The Individual Who Donate
The Graft Is Referred To As Donor And The One Who Receive The Graft Is Known As
The Recipient .Based On The Genetic Relatedness Of The Donor And The Recipient
, Transplants Are Classified Into The Following Type .
1)Auto Graft
Auto Graft Or Autologous Is A Self Tissue That Is Transplanted
From One Part Of The Body To Another Of The Same Person . This Type Of Graft Is
Done Frequently On Persons With Burns By Transferring Normal Skin To The Burned
Area . Sometime This Is Done With Surplus Tissue That Is More Desperately
Needed Elsewhere .
Eg: Vein Extraction For Coronary Bypass Surgery .
2) Iso graft
Isograft Or Syngeneic Graft Is Tissue Transferred From A Donor
To A Genetically Identical Recipient .
Eg: Transplantation Between Members Within Identical Twins .
3) Allograft
Allograft Or Allogeneic Graft Is An Organ Or Tissue Transplanted
Between Genetically Non Identical Members Of The Same Species . Most Human
Tissue And Organ Transplants Are Allograft . In This Case The Molecules On
Allograft , Called Allo antigens , Are Usually recognised By The Recipient Cells Are Foreign . This
Result In Immune Response In The Recipient’s Body That Finally Leads To Graft
Rejection . Therefore The Receiver Of Organs Or Tissues Is Put Under Immuno supressive
Drugs To Prevent Their Body’s Antibodies Causing Transplant Rejection . This
Dramatically Affects The Entire Immune System Making The Body Vulnerable To
Pathogen .
4) Xeno graft
A Xeno graft Or Xenogeneic Graft Is An Organ Or Tissue
Transplanted From One Species To Another . Xeno Transplantation Is Often An
Extremely Dangerous Type Of Transplant. A Typical Example Is The Porcine Heart
Valve , Which Is Successfully Transplanted To Human Being . The Anti geneic
Molecules In The Xenograft That Are Recognised By The Recipient Cells As
Foreign Are Called Xeno Antigens .
Reference
1)
Anju Soni , Teaching Of
General Science (2004)
Tendon Publication , Lucknow
2) Dr . R C Sharma , Modern Science Teach (2003 )
Dhanpat Rai Publishing Company P (Ltd) , New Delhi
No comments:
Post a Comment