VOA慢速英语 2007 0403b（在线收听）

VOICE ONE:

This is SCIENCE IN THE NEWS in VOA Special English. I'm Barbara Klein. 

VOICE TWO:

And I'm Bob Doughty. Today, we will tell about some disorders of the skin, and ways to treat them.

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VOICE ONE:

The skin helps control body temperature. Glands on the skin release fluid to cool the body when it gets too hot. When a person gets too cold, blood passages in the skin become narrow. This helps to trap heat inside the body. 

VOICE TWO:

Like other organs of the body, the skin can have problems. Almost any teenager can tell you the most common disorder: acne. Acne is connected to hormones and how they affect the oil glands of the skin.

The skin gets its oil, called sebum, from the sebaceous glands. Each gland connects to a passage of extremely small hairs. The sebum travels through these passages. The oil reaches the surface of the skin through little holes, called pores. Sometimes, the sebum, hair and cells of the pores block these openings. This is how acne starts. 

Bacteria can grow in a blocked pore. The bacteria produce chemicals and enzymes.  White blood cells -- infection fighters -- travel to the area. All this leads to a growth on the skin, a pimple. This becomes red, hot and often painful.

VOICE ONE:

Some people think eating chocolate or oily foods causes acne. Others blame dirty skin or nervous tension. Yet researchers tell us none of these cause acne. 

So what does? Doctors are not sure. But they have some ideas. For one thing, they know that hormones called androgens are involved. Androgens cause the sebaceous glands to grow and make more oil.

Young people will not be happy about this next fact. Androgens increase when boys and girls enter their teenage years. 

VOICE TWO:

There are several treatments for acne. Mild cases are generally treated with medicines for use directly on the skin. These often contain salicylic acid or benzoyl peroxide. 

People with more serious acne may be given antibiotic drugs to take by mouth. Or they might use a combination of other treatments.

One drug used to treat the most severe forms of acne is called isotretinoin. It is sold under different names, including Accutane. 

Isotretinoin has been shown to cure acne in ninety percent of people who use it. The drug is normally taken for about five months. However, it can cause serious problems in some cases. If used during pregnancy, for example, isotretinoin can harm the developing fetus. That is why health experts strongly advise pregnant women and those who may become pregnant against using the drug. 

VOICE ONE:

Skin experts say there are simple ways to help prevent acne. One is to touch your face as little as possible, so as not to add oils or put pressure on the skin. 

Another good idea is to avoid the urge to burst pimples. This can leave permanent marks on the skin. 

Doctors also say to avoid strong cleaning products, and to be gentle as you wash and dry your skin. 

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VOICE TWO:

A 13-year-old boy shows the scar from the removal of a cancerous growth on his arm

Skin cancer is often the result of time spent in the sun.  Light and heat from the sun can change chemicals in the skin. The sun produces ultraviolet radiation that causes the skin to burn and, over time, develop cancer.

The most serious skin cancer is melanoma. It begins in the cells that produce skin color. Melanomas can develop anywhere. They are usually found on the back and the shoulders.

Malignant melanoma

People should see a doctor immediately if they find a growth of a strange shape, with uneven sides or edges. A growth of different colors or one larger than six millimeters also should be examined.

VOICE ONE:

The usual treatment for melanoma is an operation to remove the growth. After the surgery, patients often take drugs to kill any cancer cells that remain. Doctors may also order radiation treatment. Radiation kills cancer cells and reduces the size of cancerous growths.

There also are experimental treatments for melanoma. Researchers are working on ways to genetically change white blood cells. The goal is to help the body increase its own efforts to destroy the cancer.

Researchers are also testing a possible melanoma vaccine. It would not prevent the disease like traditional vaccines. Instead, it would help the body fight the cancer in a way similar to the genetic treatment.

However, the best thing is to reduce the chances that you might ever get melanoma. Doctors tell people to limit the amount of time they spend in sunlight. They also suggest wearing hats and other protective clothing. And, they urge people to use products that help protect the skin from the sun.

VOICE TWO:

Yet there are times when doctors use ultraviolet light to treat some skin problems -- like psoriasis, for example. Psoriasis creates raised areas of skin that are dry and cause an itchy feeling. They are found most often on the elbows, knees and head. But psoriasis can spread to cover larger areas.

It usually begins before twenty or after fifty years of age. Recent studies have shown that the disorder causes the body’s defense system to produce too many skin cells. 

There is no cure, but some treatments can improve the condition. One involves the use of ultraviolet light in the doctor's office to reduce swelling and slow skin cell production. This is sometimes used in combination with a drug called psoralen.

Psoriasis seems to pass down from parent to child. Researchers have identified genes linked to psoriasis. 

VOICE ONE:

Another skin disorder is atopic dermatitis, commonly called eczema. It creates areas of skin that itch and become rough. Eczema is most common in babies. At least half of those cases clear up within a few years. But in adults this painful condition generally never goes away completely.

Persons with eczema often also suffer from allergic conditions like asthma and seasonal hay fever. Like psoriasis, there is no cure for eczema. But there are treatments with steroid drugs and also some newly developed kinds without steroids.

Environmental conditions can also influence development of eczema. That is why doctors often advise patients not to use cleaners that contain soap, which can make skin dry. Even water can cause dry skin, which can make eczema worse. So can temperature changes and stress. 

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VOICE TWO:

Some skin disorders do not cause any physical pain. But they can cause emotional pain by how they affect the appearance of the skin. Vitiligo for example, is the destruction of the pigment cells. This disease causes areas of the skin to lose all color. Even the hairs turn white.  

For some people, the white areas of vitiligo appear only in one or two places. Others find pigment loss on just one side of their bodies. Most people, however, develop many such areas all over their skin.

Around the world, up to sixty-five million people have vitiligo. It affects all races and both sexes.

Doctors do not know the cause. However, as with some other skin disorders, they suspect that the body’s immune system is involved. 

VOICE ONE:

To treat vitiligo, some patients receive psoralen and ultraviolet light. A number of steroid drugs can also help, especially when started early in the disease.

Doctors may also wish to operate to treat severe cases of vitiligo. However, American health experts say all operations should be considered only after the patient has received other medical treatment.

One such operation involves the removal of a very small piece of healthy skin from the patient. The skin is placed in a substance that helps it grow more pigment cells. These new cells are then placed in the areas where the patient needs pigment.

Vitiligo can cause extreme changes in a person’s appearance. That is why there are mental health experts and support groups to help people who have this disease.

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VOICE TWO:

SCIENCE IN THE NEWS was written by Caty Weaver. Brianna Blake was our producer.  I'm Barbara Klein.

VOICE ONE:

And, I'm Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.