Friday, 18 November 2011

Cellular Damage - A Threat To Human Life

As we age, there is an increase in the number of possible disease-causing mutations in our DNA. This makes age an important risk factor to acquire certain diseases that are life threatening. Aging is associated with a decrease in the ability to resist certain types of infections and cellular damage. This cellular damage is often caused by free radicals. To prevent free radical damage, the body has a defense system of antioxidants. Antioxidants are intimately involved in the prevention of cellular damage; which is the common pathway for cancer, and a variety of diseases like hypertension and myocardial infarction or heart attack.

Antioxidants are molecules which can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. Althoug there are severa; enzyme systems within the body that scavenge free radicals, the principal micronutrient antioxidants are Vitamin E, Beta-Carotene, and Vitamin C. The body cannot manufacture these micronutrients so they must be supplied in the diet:
  • Vitamin E, also known as D-Alpha Tocopherol is a fat soluble vitamin present in nuts, seeds, vegetable and fish oils, whole grains especially wheat germ, fortified cereals, and apricots. Current recommended daily allowance (RDA) is 15 IU per day for men and 12 IU per day for women.
  • Vitamin C, also known as Ascorbic Acid is a water soluble vitamin present in citrus fruits and juices, green peppers, cabbage, spinach, broccoli, kale, cantaloupe, kiwi, and strawberries. The recommended daily allowance (RDA) is 60 mg per day. Intake above 2000 mg may be associated with adverse side effects in some individuals.
  • Beta-Carotene is a precursor to Vitamin A (Retinol) and is present in liver, egg yolk, milk, butter, spinach, carrots, squash, broccoli, yams, tomato, cantaloupe, peaches, and grains. Because Beta-Carotene is converted to vitamin A by the body there is no set requirement. Instead the RDA is expressed as retinol equivalents (RE), to clarify the relationship. (Note: Vitamin A has no antioxidant properties and can be quite toxic when taken in excess.)

Some Common Diseases Associated With Cellular Damage
Cells can experience uncontrolled growth if there are damages or mutations to DNA, and therefore, damage to the genes involved in cell division. Four key types of gene are responsible for the cell division process: oncogenes tell cells when to divide, tumor suppressor genes tell cells when not to divide, suicide genes control apoptosis and tell the cell to kill itself if something goes wrong, and DNA-repair genes instruct a cell to repair damaged DNA. Some of the common diseases associated with cellular damage are listed below:

  1. Hypertension, more commonly known as high blood pressure, is a physiological condition involving increased pressure on the arterial walls. Generally, both systolic and diastolic pressures are elevated, although diastolic pressure may be increased. Many people have a condition known as liable hypertension, in which blood pressure is elevated on initial examination but registers normal on subsequent measurements. The average age of onset of essential hypertension is about 35. Most people with hypertension have no symptoms. For this reason, large-scale screening programs have been instituted to detect people with elevated blood pressure, for if left untreated, hypertension increases the risk of death from heart attack and produces damage to the kidneys, nervous system, and especially the eyes. 
  2. Heart Diseases or disorders of the heart kill people than any other disease. They can arise from congenital defects, infection, narrowing of the coronary arteries, high blood pressure, or disturbances of the heart rhythm. Congenital heart defects include persistence of fetal connections, such as the ductus arteriosus, a vessel normally connecting the pulmonary artery and the aorta only until birth. Rheumatic heart disease was formerly one of the most serious forms of heart disease of childhood and adolescence, involving damage to the entire heart and its membranes. It usually followed attacks of rheumatic fever. Widespread of antibiotics effective against the streptococcal bacterium that causes rheumatic fever has greatly reduced the incidence of this condition. Myocarditis is inflammation or degeneration of heart muscle. Although it is often caused by various diseases in adults or as a degenerative disease such as syphilis, goiter, endocarditis, or hypertension, myocarditis may appear as a primary disease of old age. It may be associated with dilation (enlargement due to weakness of the heart muscle) or with hypertrophy (overgrowth of the muscle tissue). In a condition called atherosclerosis, fatty deposits called plaque, composed of cholesterol and fats, build up on the inner wall of the coronary arteries. Gradual narrowing of the arteries throughout life restricts the blood flow to the heart muscles. Symptoms of restricted blood flow can include shortness of breath, especially during exercise, and a tightening pain in the chest called angina pectoris. The plaque may become large enough to completely obstruct the coronary artery, causing a sudden decrease in oxygen supply to the heart. Obstruction, also called occlusion, can occur when part of the plaque breaks away and lodges farther along in the artery, a process called thrombosis. These events are the major causes of heart attack, or myocardial infarction, which is often fatal.
  3. Cancer, a class of diseases characterized by out-of- control cell growth.

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