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Biomedical Technologies

Introduction

     Doctors use a number of simple instruments like thermometer to monitor body temperature of patients, stethoscope to listen to heart sounds, BP instrument to check the blood pressure, BP instrument to check the blood pressure and so on. But today technology has revolutionised the world of medicine and the tools used for diagnosis of diseases.

X-ray Radiography

     X-rays and scanners help doctors to learn a great deal about the body as they reveal defects and abnormalities and thus contribute to diagnosis.

Angiography

     Angiography involves injecting a dye directly into the blood and then taking X-rays of the arteries. Angiography of the blood vessels of the heart is called Coronary angiography.

Computed Tomography

     In conventional X-rays an overlap of organs occurs and often difficult to interpret. These diagnostic difficulties have been eliminated by the use of an X-ray technique called computer Tomography (CT) scaning or computerised Axial Tomography (CAT) Scanning.

Magnetic Resonance Imaging

     It is also called Nuclear Magnetic Resonance (NMR) spectroscopy as it is based on this phenomenon. It is a diagnostic technique that provides high quality cross-sectioned two or three - dimensional images of organs without having X-rays or other radiations.

Positron Emission Tomography (PET)

     The principle behind PET scanning is as follows. Short - lived radio isotopes such as 11C, 13N or 15O are produced and incorporated into a solution (of glucose) that can be injected into the body.

Sonography

     It is also called Ultrasonography. It involves the use of high frequency ultrasonic sound waves to produce images of structures within the human body.

Electrocardiography

     In a hospital, especially in the Intensive care unit (ICU), where seriously ill patients are treated, monitoring of the patients heart rate, blood pressure, temperature, oxygen level in blood etc. is very important. Electronic biomedical equipments continuously monitor the patients vital signs. This helps the doctor to get information about the patients condition, and thus in treatment.

Electroencephalography

     Brain cells can generate electrical activity as a result of literally millions of action potentials of individual neurons. These electrical potentials are called brain waves and indicate activity of the cerebral cortex. Brain waves pass through the skull easily and can be detected by sensors called electrodes. A record of such waves is called an Electro encephalogram (EEG). EEG is the graphic representation of the electrical activity of the brain cells which are picked up by the electrodes placed on the scalp. The instrument used to prepare an EEG is called Electroencephalograph.

Polygraphy

     Polygraph is a simple instrument that records qualitative changes in physiological parameters. These parameters include vital changes like cardiac variables (ECG), heart pulse rate (HR), relative blood pressure (BP), rate of breathing and so on. Popularly called the lie detector. A modern improved version of this device is used to record, neuro physiological parameters such as brain activity by EEG, EMG (Electro myograph) to record muscle tonus, and EOG (Electro oculograph) to record eye movements.

Biochemical Auto Analysers

     Auto analysers are Bio medical equipments, which are computer controlled and temperature regulated. These equipments can analyse hundreds of samples in a short time. Samples are introduced into these multichannel equipment, at regular intervals through micropipettes. The reagents are mixed in the sample and the results are obtained. Semi-automated analysers can estimate only one parameter like glucose, urea etc at a time. But recent analysers can analyses 40 or more parameters simultaneously in a sample as per the requirement.

Diagnostic Kits - Enzyme - Linked Immunosorbent Assay (ELISA)

     ELISA technique is widely used for the detection of viruses, fungi, bacteria etc. It is a very sensitive and specific test and needs a very small amount of reagents. It is used to detect the infectious diseases like tuberculosis, AIDS etc.

Diagnostic Kits - Endoscopy

     Endoscopy is an important tool for gastro enterologists and other specialists dealing with problems of the digestive tract. Ensoscopes are thin, flexible telescopes that allow trained specialists to examine most areas of the gut. At the end of the endoscope is a tiny television camera, which allows the doctor to see the lining of the gut in close up and in colour on a television monitor.

Diagnostic Kits - Laser Microsurgery

     Microsurgery is any operation done with the aid of microscopes. Surgeons work with spectacle - mounted magnifiers or with microscopes. Using this technique, surgeons can remove adenoma, tumours of the pituitary gland, without damaging the gland itself. Neurosurgeons, ear and eye surgeons all rely on microsurgery.

Cancer Biology and Therapy

     Cancer is characterised by uncontrolled growth and division of certain body tissues, so forming a tumour. It is one of the major killers today.

Properties of Cancer Cells

     Cancer cells show uncontrolled mitotic divisions causing unorganised growth.

Types of Cancer

     These cancers are located in the epithelial lining of internal organs or glands. For e.g., Breast cancer, Stomach cancer etc., Cancers of epithelial glands are called Adenoma. About 85% of all tumours are of this kind.

Metastasis

     Initially the tumour shows slow growth, called Latent stage. But later growth rate becomes very rapid, causing overcrowding and damage to normal cells. But later these enter the metastasia stage (stage of secondary growth) in which the cancer extends to the neighbouring tissues like the roots of a tree. Small pieces of primary tumour breaks off and are carried to other parts of the body by blood or lymph, where these form the secondary tumours. This process is called metastasis.

Causes of Cancer

     A chemical or other environmental agent that produces cancer is called a carcinogen. The world Health organisation estimates that carcinogens may be associated with 60 - 90% of all human cancer.

Detection and Diagnosis of Cancer

     Histologic and Cytologic methods involve Biopsy and histological examination of the affected tissue. For e.g., Paps test is employed to detect cervix cancer. Blood tests for abnormal WBC count for Leukaemia, Bone marrow Biopsy are also used to detect Leukaemia.

Treatment of Cancer

     Treating cancer is difficult because it is not a single disease and because all the cells in a single tumour do not behave in the same way. Cancer can be controlled in early stages and control depends upon the locations and spread of the cancer. So, the key to cancer treatment is early detection. The therapeutic strategies vary, depending on the etiology of each individual cancer.

Organ Transplantation

     Organ transplantation has become a therapeutic modality to treat patients with end - stage disease. While many types of organs have been successfully transplanted, the histocompatibility barrier between recipient and donor remains a problem. It activates immune responses leading to graft rejection.

Haemodialysis

     If the kidneys are so impaired by disease or injury that they are unable to excrete nitrogenous wastes and regulate pH and electrolyte concentration of the plasma, the blood must be filtered by an artificial device. Such filtering of the blood is called Haemodialysis.

Prosthesis

     Prosthesis is implanting an artificial substitute for a body part either externally or even internally. The branch of surgery dealing with prosthesis is called Prosthetics.

Heart Lung Machine

     Before surgeons can perform open-heart surgery or heart transplants or even to correct a simple heart defect, they have to be able to open up the heart and expose the chambers. To enable this, circulation and respiration are maintained by the heart - lung machine. The function of the heart is performed by a roller pump. Oxygenation of blood is carried out by an oxygenator, which is the artificial lung. This is a heart lung bypass, where by blood bypasses the heart and lungs completely. Blood is pumped and oxygenated by the machine outside the body. The heart lung machine thus functions as the heart and the lung. This helps the surgeons to perform the surgery or procedure. Modern heart - lung machines may also chill the blood to produce hypothermia (low body temperature to slow metabolism and reduce oxygen need) as well.

Prosthetic Cardiac Pacemaker

     The sinoatrial node, known as SA node is located in the right atrial wall below the opening of the superior vena cava. The SA node initiates the cardiac cycle and sets the basic pace for the heart rate, hence called the pacemaker.

Defibrillator

     Fibrillation is abnormal and asynchronous contraction of the heart muscles. This reduces the proper effectiveness of heart pumping. Atrial fibrillation is irregular and faster contract ions of atria. It may occur in myocardial infarction and in rheumatic heart disease. Ventricular fibrillation is an abnormality, which generally indicates. Cardiac arrest. It is characterised by asynchronous and haphazard ventricular contractions, either rapid or slow.

Angioplasty

     This is a technique by which the blocked coronary arteries due to atherosclerotic plaque are unblocked Baloon catheters are used to dilate partially or completely obstructed coronary arteries as well as other blood vessels. A balloon catheter is inserted into an artery of the arm or thigh. The catheter is then guided to the obstructed artery, blown up briefly and then withdrawn. This procedure compresses the obstructing material against the vessel wall, allowing better blood flow. In some instances, this procedure prevents limb amputations and coronary by pass surgery.

Replacement Surgery

     In this type of surgery, following the removal of a damaged or diseased organ or a part, it is replaced by prosthesis. It can be a hip, shoulder or elbow joint or knee.

Vascular Graft

     In case of coronary thrombosis, the damaged vessel has to be reconstructed. This is done by using a synthetic tube made of Teflon or woven Dacron. A special device called stent, which is a spring coil like structure made of stainless steel, which is placed in an artery through a catheter. This will ensure dialation of the artery, and adequate blood will flow through the artery to the heart muscle.

Coronary Artery Bypass Grafting (CABG)

     If a part of the coronary artery is blocked, this surgical procedure is done. Here, a blood vessel from another part of the body is used to bypass the blocked region of the coronary artery.

Cryosurgery

     Cryosurgery is using freezing temperatures to destroy tissues. Liquid nitrogen or a solution of nitrous oxide is used. If these chemicals are sprayed onto the tissue, it will destroy the tissue. Treatment of warts as well as destroying of cancerous tumours can be done by this technique.

Immuno Therapy

     This is a technique of suppression or augmentation of immune responses, to achieve therapeutic effects. Immuno modulators are drugs, which modulate the patients immune response. It will either improve or reduce, until the required level is reached.

Hormone Therapy

     Whenever there is a hormonal deficiency or hormonal imbalance, hormone therapy is given. For e.g., Estrogen Replacement Therapy popularly known as Hormonal replacement Therapy (HRT) is a treatment prescribed for the complications and after effects of Menopause. In this therapy, Progestin is taken with estrogen.

Gene Therapy

     Gene therapy is a relatively new method of therapeutic interventions, targeted at the level of cellular gene expansion. In this, altering the diseased state is achieved by delivering nucleic acids into a cell. In gene therapy a normal functional gene is introduced into cells that contain the defective allele of the gene. The aim is to correct the disorder. The gene is inserted into the viral vector, which is then introduced into somatic cells. Or the gene, portions of genes or RNA may be introduced into somatic cells directly. The introduced gene is in addition to the defective gene or it can replace the defective gene.

Detection of HIV Infection

     Some people show the symptoms of HIV infection within a few weeks of contracting the virus. Some may take years to manifest the disease. Symptoms of AIDS may develop for months or for years and include Malaise, a low - grade fever, coughing, shortness of breath, sore throat, muscle aches, weight loss, nausea, headache, rashes, enlarged lymph nodes in the neck, axilla and groin. The principal problem associated with AIDS is that its victims have too few T cells, and therefore a weakened immune system.

Signs and Symptoms of AIDS

     People infected with AIDS virus remain apparently by well even after infection. They may not show any physical symptoms of illness for a long time.

Detection of Sexually Transmitted Diseases

     Sexually transmitted diseases (STDs) are those infections and communicable diseases, which are transmitted from an infected person to a healthy but susceptible person during unprotected sexual contact. These usually affect the reproductive system but may spread to other body parts as well. STDs are caused by Bacteria, Protozoa and viruses.

Summary

     Non-invasive diagnostic techniques are those that can be applied without penetrating the skin.



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