 |
Business | Industries | Finance | Tax |
| Index: > A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
|
|||||
| First Prev [ 1 2 ] Next Last |
KS lesions are nodules or blotches that may be red, purple, brown, or black, usually painless but sometimes painful and swollen. They appear under the surface of the skin or on mucous membranes, but may also be found in internal organs, particularly the respiratory system or gastrointestinal system; internal lesions are most commonly seen in epidemic KS.
Skin or mucous membrane lesions are not fatal unless they cause enough swelling to obstruct circulation or breathing, or lesions in the mouth or esophagus prevent eating. Lesions affecting the internal organs are much more often fatal. KS can occur among transplant patients in whom the tumor can disseminate. Stopping immunosuppression can eliminate KS but also can cause rejection of the transplanted organ.
KS lesions contain tumor cells with a characteristic abnormal elongated shape, called spindle cells. The tumor is highly vascular, containing abnormally dense and irregular blood vessels, which leak red blood cells into the surrounding tissue and give the tumor its dark color. Inflammation around the tumor may produce swelling and pain.
Although KS may be suspected from the appearance of lesions and the patient's risk factors, a definite diagnosis can only be made by biopsyA biopsy is a medical test involving the removal of cells or tissues for examination. The tissue is often examined under a microscope and can also be analyzed chemically (for example, using PCR techniques). When only a sample of tissue is removed, the pro and microscopic examination, which will show the presence of spindle cells. Detection of the viral protein LANA in tumor cells confirms the diagnosis.
There is no known cure for KS. Treatment is focused on eliminating the existing lesions, by means of chemotherapyChemotherapy (pronounced keem-o-therapy is the use of certain drugs to treat disease, as distinct from other forms of treatment, such as surgery. Chemotherapy dates at least as far back as the use, by the Indians of Peru, of cinchona bark in the treatment drugs such as paclitaxel and bleomycinBleomycin is an anti- cancer agent. It is a glycosylated linear nonribosomal peptide antibiotic produced by the bacterium Streptomyces verticillus''. It acts by induction of DNA strand brakes and is used in the treatment of lymphomas, squamous cell carcin, radiation therapy, or surgical removal. However, this does not prevent new lesions from developing. Treatment with drugs such as ganciclovir that target the virus causing Kaposi's sarcoma may prevent new tumors but do not adequately treat existing lesions.
The disease is named after Moritz Kaposi ( 1837Events January 10 DePauw University founded in Greencastle, Indiana January 26 Michigan is admitted as the 26th U. State February 8 Richard Johnson becomes the first Vice President of the United States chosen by the United States Senate February 11 Americ- 1902Events January-April January 28 The Carnegie Institution is founded in Washington, DC with a $10 million gift from Andrew Carnegie. France, Loisy's L'evangile et l'Eglise which inaugurates the Modernist Crisis February 11 Police beat up universal suffrage), a HungarianThe Republic of Hungary is a landlocked country in Central Europe, bordered by Austria, Slovakia, Ukraine, Romania, Serbia, Croatia and Slovenia. It is known locally as the Country of the Magyars or Magyarorszag''. Magyar Koztarsasag ( In Detail) ( Full s dermatologist who first described the symptoms in 1872Events January 2 Brigham Young, is arrested for bigamy (25 wives). February 20 In New York City the Metropolitan Museum of Art opens. March 1 Yellowstone National Park is established as the world's first national park March 5 George Westinghouse patents t. Research over the next century suggested that KS, like other forms of cancer, might be caused by a virus or genetic factors, but no definite cause was found.
With the advent of the AIDS epidemic, KS, as one of the most common AIDS symptoms, was researched more intensively in hopes that it might reveal the cause of AIDS. Some researchers suspected that HIV itself directly caused KS; others thought that it was simply a result of the immune system losing its ability to protect against some common cancer-causing agent; and others took it as a sign that AIDS was not primarily a viral disease at all but an effect of toxic chemicals that can damage the immune and vascular systems, such as nitrite poppers.
Research since 1994 has led to a consensus that the primary cause of KS is the herpesvirus HHV-8, sometimes referred to as Kaposi's sarcoma-associated herpesvirus (KSHV). KSHV is almost always found in KS tissue samples. However, KSHV infection does not always lead to KS and it is still unclear what other factors may be required, such as pre-existing immune system damage, or a specific interaction with HIV or other viruses. KSHV is a unique human tumor virus that has incorported cellular genes that cause tumors into its genome ("molecular piracy"); the stolen cellular genes may help the virus escape from the immune system, but in doing so it also causes cells to proliferate. It is related to Epstein-Barr virus, a very common herpesvirus that can cause human cancers.
The fact that KS occurs much more often in males than in females has not been entirely explained. In the early years of the AIDS epidemic in North America and Western Europe, the incidence of KS almost exclusively among male homosexual AIDS patients suggested that it was spreading as a sexually transmitted infection within that population, or was due to other lifestyle factors. However, research in Africa has shown that even in the absence of HIV/AIDS, KS is more common in men than women although KSHV infection is equal between both sexes. This suggests that sex hormones may either protect from or predispose to KS in persons infected with the virus.
| Politics | Business | Finance |
 |
 |
 |
|