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Genetic engineering is a technique of manipulating the DNA in cells to endow an organism with qualities it did not naturally possess. The technique is also called gene manipulation. It entails a number of steps the first of which is the constitution of DNA segment from nucleic acid molecules in a test tube. The length of DNA so made is inserted into a virus or some other suitable vector that can serve as a molecular ferry to carry it into the host organism. The crucial factor here is ability of the inserted DNA molecule to express itself and also to multiply. Bacteria and even higher animals may be genetically engineered to produce foreign proteins of interest by inserting a copy or multiple copies of the gene coding for the protein into them. Several important products of medical use such as insulin and the human growth hormone are now being produced commercially using genetically engineered bacteria. ‘Tracy’, a genetically engineered sheep produces the pharmaceutically important protein called Alpha-1 antitrypsin in her milk. Genetic engineering may be used to boost growth, alter resistance to factors such as drugs, heat, cold and salinity in both animals and plants. 

Gene therapy is a new and as yet largely experimental branch of medicine that incorporates techniques of genetic engineering to correct inherited disorders or in-born errors of metabolism. The idea of curing a genetic disorder by repairing or replacing a faulty gene or gene product (protein) first occurred to Dr. W. French Anderson now recognized as the father of gene therapy.

In gene therapy the flawed gene is identified and copies of its normal version are produced in the laboratory by cloning. Then suitable host cells are selected from the patient’s body and genetic engineering is used to transfer copies of the normal version of the gene into it. The doctored cells are then returned to the body by injection. The introduced genes are incorporated into the chromosomes of the patient’s cells and propagate with each cell division. Since the introduced genes work normally and produce the protein that was previously either absent or malformed, the error is corrected in the victim who gets cured of the symptom. However, since gene therapy is not approved for genetic manipulation of the germ or reproductive cells, the cure cannot be passed onto future generations of the cured victims. 

Cholesterol is a complex fatty substance that is essential for the normal functioning of the body such as formation of membranes covering the cells or the synthesis of hormones, but harmful when in excess. It is considered to be the chief cause for the narrowing of arteries which at times is known to cause heart attacks. Pure cholesterol is solid at room temperatures and is insoluble in water. It is present in all tissues of the human body in varying concentrations. An adult human has in total about 60 grams of cholesterol in the body about one gram of which is used up everyday. The lost cholesterol is made up in the liver through digestion of foods especially rich in a kind of fat substance called high density lipoproteins (HDLs). Cholesterol is harmful only when it is in excess amounts in the blood. This happens with the excessive intake of HDL-rich food such as animal fats, palm oil and coconut oil. The excess of cholesterol in the blood slowly settles on the insides of blood vessels narrowing their bore. This condition called atherosclerosis increases blood pressure and causes heart attacks and strokes. 

 

Cat scan (Computerized Axial Tomography), sometimes also referred as CT scan, is a technique of obtaining X-ray pictures of thin slices of the body without even putting a scalpel to it. The technique comes to help in locating or identifying tumours or blocked blood vessels in such soft tissues as the brain or in large organs such as the liver which cannot be photographed by the usual X-ray techniques.

CAT scanning is a modification of the usual X-ray technique. In CAT, the part of the body to be scanned is placed inside a ring. The ring has an X-ray gun at one side and a detector on the opposite side. The X-ray beam from the gun is received by the detector after passing through the body.

 

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Cancer is the abnormal, uncontrolled growth of a group of cells in the body. They grow uncontrollably to form abnormal localized lumps of tissue called tumours and wander from their original site to other organs of the body, starting fresh growths. Tumours which spread to other parts of the body are known as ‘malignant’ tumours, unlike the ‘benign’ ones which are rooted to their site of origin and are usually harmless.

Currently, there are three ways of treating cancer. First is the surgical removal of the original tumour and as many secondary tumours as possible. Radiation therapy is the second method whereby cancer cells are destroyed using ultra powerful gamma rays from radium. Some anti-cancer drugs are also available which can control cancer.

But most of ods, besides these meth-killing cancer cells can cause damage to the surrounding normal tissues producing serious side-effects. Recent advances in genetic research, however, offer promising new approaches to treat cancers. 

By-pass surgery is a technique of treating patients with blocked coronary arteries which impair functioning of the heart. Coronary arteries are the blood vessels that supply blood to the heart muscles. They can narrow gradually and may even become completely blocked due to deposition of fatty substances. When this happens, blood supply to a particular part of the heart is reduced or cut off and the patient suffers from severe chest pain or may even collapse. An alternate path for blood-supply by-passing the blocked artery is then provided by attaching a piece of vein taken from the patient’s own leg.

During the by-pass surgery, the patient’s heart is emptied of blood by inserting two tubes, one into the aorta and the other into the vena cava. These two tubes are connected to a heart-lung machine which takes over the pumping and oxygenation of blood during the surgery. The patient’s heart once empty stops spontaneously or can be stopped by giving special drugs or by an electric shock for the surgery to be carried out.

Biopsy is a simplified procedure of obtaining tissues from affected part(s), usually some unusual growth or lining of an organ for microscopic examination.

To obtain tissue from deeply situated organs like liver or kidney, a hollow needle is used. Soft spongy material such as bone marrow can also be obtained by suction through the needle.

The tissue after removal is either frozen or fixed in wax for preservation. Later, thin slices are cut, stained with special colours for clarity and examined under the microscope to ascertain whether the tissue is benign (non-cancerous) or malignant (cancerous).

 

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The sum total of all living plants, animals and microbes is what is called biodiversity. The term has come to the fore-front because large-scale habitat destruction and alteration has led to the extinction of a large number of species. For a biologist biodiversity refers to the variety and variability of all living forms on earth. Some of this diversity is essential, in that mankind is dependent on other species for the maintenance of the biosphere and the supply of basic necessities, particularly food.

            Any description of biodiversity involves large and uncertain numbers. Estimates suggest that there are about 5 to 30 million living species, of these only 1.4 million have been described. On the other hand, species extinction rates are estimated at approximately 10,000 to 20,000 per year.

            Conserving this biodiversity is of immediate importance to humans because plants and animals hold in them a lot of unknown treasures like cures for diseases and genes to increase the yield of our food crops.

            The highest level of biodiversity is found in the warm tropical regions. Tropical rain forests and coral reefs are two areas that are extremely rich in species composition.

This is the process by which living organisms breakdown matter into its simpler constituents and thus recycle nutrients. All natural decay processes such as rotting of wood are examples of biodegradation. The life forms responsible for the process are called decomposers and they form a vast, complex community of soil organisms such as microbes and fungi. All such matter on which they can act is termed biodegradable to distinguish it from non-biodegradable matter or such matter which is not broken down by biological agents. While all organic matter is biodegradable, certain decomposers can attack even metal, glass and plastic. The widespread use of non-biodegradable material such as the various types of plastics is a cause for alarm because when discarded they do not decompose easily but remain in the environment as pollutants. Efforts are underway to develop biodegradable plastics which will be more environments friendly.

Acupuncture is an ancient healing art practiced by the Chinese for several thousand years. The Chinese believed that all our experiences have opposites, which they call Yin and Yang. The Yin and Yang merge and complement each other, creating a balance. A disease may develop if this balance is disturbed. According to the Chinese theory, Yin and Yang energies flow through channels in our body called meridian lines. Acupuncture involves insertion of tiny needles in any of the thousand or so spots along these meridian lines. Each spot represents a particular function or organ of the human body.

            According to a modern theory there are reflex mechanisms in the nerve paths which can shut off pain signals. Acupuncture works by closing these gates. A second theory explains the pain relieving effects of acupuncture on the basis of the production of endorphins. There is evidence to show that acupuncture causes release of these hormones which then travel to the brain and activate a mechanism blocking the pain messages. Although acupuncture has proved helpful in the treatment of several as headaches, insomnia, and rheumatic, respiratory, digestive, sex-related, and heart problems, it is not a cure-all.