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المواد المســرطنة - Cancer's Oncogenes الخلايا السرطانية و المواد المسرطنة

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قديم 02-09-2007, 02:56 AM   #1
yaak
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افتراضي Sickle cell anemia

Sickle cell anemia occurs when a person inherits two abnormal genes (one from each parent) that cause their red blood cells to change shape. Instead of being flexible and round, these cells are more rigid and curved in the shape of the farm tool known as a sickle - that's where the disease gets its name. The shape is similar to a crescent moon.

What Is Sickle Cell Anemia ?
Sickle cell anemia is a blood disorder that affects hemoglobin (pronounced: hee-muh-glow-bin), a protein found in red blood cells that helps carry oxygen throughout the body.

Red blood cells with normal hemoglobin (HbA) move easily through the bloodstream, delivering oxygen to all of the cells of the body. Normal red blood cells are shaped like doughnuts with the centers partially scooped out and are soft and flexible.

Sickle cell anemia occurs when an abnormal form of hemoglobin (HbS) is produced. HbS molecules tend to clump together, making red blood cells sticky, stiff, and more fragile, and causing them to form into a curved, sickle shape. Red blood cells containing HbS can go back and forth between being shaped normally and being sickle shaped until they eventually become sickle shaped permanently. Instead of moving through the bloodstream easily, these sickle cells can clog blood vessels and deprive the body's tissues and organs of the oxygen they need to stay healthy.

Unlike normal red blood cells that last about 4 months in the bloodstream, fragile sickle cells break down after only about 10 to 20 days, which usually causes anemia. Anemia (pronounced: uh-nee-mee-uh) is what happens when the body's number of red blood cells (or amount of hemoglobin) falls below normal. People who are anemic often feel weak and tire more easily.


People with sickle cell anemia can also experience complications from blood circulation and infection-fighting problems. These include a higher risk of certain infections and stroke as well as a condition called acute chest syndrome, which is caused by infection or trapped red blood cells in the lungs.

Sickle cell anemia is not contagious, so you can't catch it from someone else or pass it to another person like a cold or other infection. People with sickle cell anemia have inherited two sickle cell genes, one from each parent. A child who has inherited the sickle cell gene from only one parent will not develop the disease, but will have sickle cell trait. People who have sickle cell trait don't have sickle cell anemia or symptoms of the disease, but they can pass the sickle cell gene to their own children.

Because people with sickle cell trait don't have the disease, they may never discover that they carry the gene. That's why it's recommended that teens who are unsure of their sickle cell status ask their doctors about testing. The National Institutes of Health recommends that all newborns be screened for sickle cell disease, and testing at birth is now required in almost every state. This helps infants with sickle cell anemia get the care and treatment they need right away.
Signs and Symptoms
Teens with sickle cell anemia may develop jaundice (pronounced: jon-dis), a condition that results from the high rate of red blood cell breakdown. Jaundice can cause the skin and the whites of a person's eyes to develop a yellowish tint.

People with sickle cell anemia also may have bouts of pain in the chest, stomach, arms, legs, or other parts of the body. This is caused by sickle cells blocking blood flow through the blood vessels. Feeling tired and having trouble fighting infections are also common among teens with sickle cell anemia, and they may grow more slowly and reach puberty later than other teens.

Periods of pain are commonly referred to as crises, which vary in their severity, how often they happen, and how long they last. Whereas one person may have only one sickle cell crisis a year, another may experience crises more often. Crises may be brief, or may last hours, days, or even weeks. Symptoms can develop in any body organ or tissue and include aching arms, legs, hips, and shoulders. When people with sickle cell disease get acute chest syndrome, they may have severe chest and abdominal pain, fever, cough, and trouble breathing.

What Can You Do to Stay Well?
With the right precautions, teens with sickle cell disease can do most of the stuff other teens do. To stay as healthy as possible, people with sickle cell anemia should take these steps:

Eat a balanced, healthy diet.
Take vitamins, including folic acid supplements, as prescribed.
Drink plenty of water to prevent dehydration.
Avoid extreme cold or heat.
Exercise regularly, but in moderation. Exercise is important for staying healthy, but overdoing it can trigger a crisis in some people, particularly if they become dehydrated, overheated, or exhausted.
Get plenty of rest.
Avoid alcohol, drugs, and smoking, which can aggravate sickle cell disease and its symptoms. Some people with sickle cell disease are prone to lung problems, so smoking is particularly risky.
Avoid places low in oxygen. (For example, it's not a good idea to go hiking at high altitudes or spend lots of time swimming under water.)
Prevent serious infections by contacting your doctor as soon as illness symptoms start. Be sure to get any immunizations (such as pneumonia and flu vaccines) that the doctor recommends.
Learn as much as you can about the disease and see your doctor regularly to help prevent complications.
There are some limits that people with sickle cell disease may need to put on their lives, but with the help of doctors, friends, and family, teens with sickle cell anemia can manage the disease and live their lives to the fullest.

اتمنى اني اعطيت لمحه عن هذا المرض والذي منتشر في السعوديه والسبب يرجع الى زواج الاقارب



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التعديل الأخير تم بواسطة yaak ; 02-09-2007 الساعة 03:07 AM
   
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