DNA sequence?

A DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carryinformation as described by the central dogma of molecular biology.

The possible letters are A, C, G, and T, representing the four nucleotide bases of a DNA strand — adenine, cytosine, guanine, thymine — covalently linked to a phosphodiesterbackbone. In the typical case, the sequences are printed abutting one another without gaps, as in the sequence AAAGTCTGAC, read left to right in the 5' to 3' direction. Short sequences of nucleotides are referred to as oligonucleotides and are used in a range of laboratory applications in molecular biology. With regard to biological function, a DNA sequence may be considered sense or antisense, and either coding or noncoding. DNA sequences can also contain "junk DNA."

Sequences can be derived from the biological raw material through a process called DNA sequencing.

HIV TREATMENT

Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a set of symptoms and infections resulting from the damage to the human immune system caused by the human immunodeficiency virus (HIV). This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk.[This transmission can involve anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids.AIDS is now a pandemic. In 2007, an estimated 33.2 million people lived with the disease worldwide, and it killed an estimated 2.1 million people, including 330,000 children. Over three-quarters of these deaths occurred in sub-Saharan Africa, retarding economic growth and destroying human capital. Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century.AIDS was first recognized by the U.S. Centers for Disease Control and Preventio in 1981 and its cause, HIV, identified by American and French scientists in the early 1980s.Although treatments for AIDS and HIV can slow the course of the disease, there is currently no vaccine or cure.

HIV/AIDS TREATMENT AND CARE

HIV/AIDS Treatment And care

June 2008 — Health experts estimate that approximately 25% of Americans infected with HIV do not know their status — a figure that has profound public health implications. In fact, evidence suggests that most new infections stem from people who are unaware of their HIV status, according to the U.S. Centers for Disease Control and Prevention (CDC).All sexually active people, particularly those who have had multiple sex partners — gay or straight— should get tested. Even people in monogamous relationships should be tested and should know their partner’s status.What is an HIV test? When HIV enters the bloodstream, it begins to attack certain white blood cells known as CD4 cells. The immune system then produces antibodies to fight off infection. When you take an HIV test, doctors are actually looking for the presence of these antibodies, which confirm that HIV infection has occurred. Why should I get tested? Early diagnosis is crucial in preventing life-threatening health conditions and combating the spread of HIV. Knowing your status will allow you to take steps to protect your health and the health of others. If you know you are HIV-positive and pregnant, you can take medications and other precautions—such as refraining from breast-feeding— to significantly reduce the risk of infecting your child.Am I at risk? Anyone can become infected with HIV, but you are at greater risk if you:Have ever shared injection drug needles and syringes or “works.”Have ever had unprotected vaginal, anal, or oral sex with multiple sex partners, anonymous partners, or men who have sex with men.Have ever been diagnosed with or treated for hepatitis, tuberculosis (TB) or a sexually transmitted disease such as syphilis.Exchanged sex for drugs or money.Received a blood transfusion or clotting factor between 1978 and 1985.Have had unprotected sex with someone who would answer yes to any of the above questions.If you are unsure of a sexual partner’s risk-taking behavior or if you or they have had many sex partners, you are at greater risk of infection.The CDC recommends that all pregnant women be screened for HIV. In the U.S., mother-to-child HIV transmission is highly preventable if the mother begins treatment before or during childbirth.Can’t I tell whether I’m infected without getting tested? No. The only way to know for sure is to be tested. Within a few weeks after infection with HIV, some people may develop temporary flu-like symptoms or persistent swollen glands, but many people feel healthy for a decade, and some for even more. Unfortunately, HIV- infected people who look and feel perfectly healthy can still transmit the virus to others. When and how can I get tested? Most people develop detectable HIV antibodies within three months of infection, the average being 20 days. In rare cases, it can take 6-12 months. For this reason, the CDC recommends testing six months after the last possible exposure, i.e, unprotected vaginal, anal, or oral sex, or sharing needles. You can be tested at your doctor’s office, local health department, hospital, and sites specifically set up to provide HIV testing. All HIV test results are confidential and can only be shared with people authorized to see your medical records. Anonymous testing sites allow you to get tested without giving your name.It is important to seek testing at a place that also provides counseling about HIV and AIDS. Counselors can answer questions about behavior that may put you at risk of contracting or transmitting HIV and suggest ways you can protect yourself and others in the future. They can also help you understand the meaning of the test results and refer you to local AIDS-related resources.The CDC provides a national database of HIV testing sites (see sidebar).What types of HIV tests are available? Several HIV antibody tests are used today. The most common are blood and oral fluid tests. Unlike most testing methods, which can take anywhere from three days to several weeks, rapid HIV testing offers results in 20 minutes to an hour. Although these tests are very accurate, all positive HIV results must be confirmed with a follow-up test before a final diagnosis of infection can be made

MRI Scans

Also called: Magnetic resonance imaging, NMR, Nuclear magnetic resonance

Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body. Health care professionals use MRI scans to diagnose a variety of conditions, from torn ligaments to tumors. MRIs are very useful for examining the brain and spinal cord.

During the scan, you lie on a table that slides inside a tunnel-shaped machine. Doing the scan can take a long time, and you must stay still. The scan is painless. The MRI machine makes a lot of noise. The technician may offer you earplugs.

Before you get a scan, tell your doctor if you

• Are pregnant
• Have pieces of metal in your body. You might have metal in your body if you have a shrapnel or bullet injury or if you are a welder
• Have electronic devices in your body, such as a cardiac pacemaker

What are the benefits vs. risks? of CT Scan

• CT scanning is painless, noninvasive and accurate.
• A major advantage of CT is its ability to image bone, soft tissue and blood vessels all at the same time.
• Unlike conventional x-rays, CT scanning provides very detailed images of many types of tissue as well as the lungs, bones, and blood vessels.
• CT examinations are fast and simple; in emergency cases, they can reveal internal injuries and bleeding quickly enough to help save lives.
• CT has been shown to be a cost-effective imaging tool for a wide range of clinical problems.
• CT is less sensitive to patient movement than MRI.
• CT can be performed if you have an implanted medical device of any kind, unlike MRI.
• CT imaging provides real-time imaging, making it a good tool for guiding minimally invasive procedures such as needle biopsies and needle aspirations of many areas of the body, particularly the lungs, abdomen, pelvis and bones.
• A diagnosis determined by CT scanning may eliminate the need for exploratory surgery and surgical biopsy.
• No radiation remains in a patient's body after a CT examination.
• X-rays used in CT scans usually have no side effects.

Risks

• There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.
• The effective radiation dose from this procedure ranges from approximately two to 10 mSv, which is about the same as the average person receives from background radiation in three to five years. See the Safety page for more information about radiation dose.
• Women should always inform their physician and x-ray or CT technologist if there is any possibility that they are pregnant. See the Safety page for more information about pregnancy and x-rays.
• CT scanning is, in general, not recommended for pregnant women unless medically necessary because of potential risk to the baby.
• Nursing mothers should wait for 24 hours after contrast material injection before resuming breast-feeding.
• The risk of serious allergic reaction to contrast materials that contain iodine is extremely rare, and radiology departments are well-equipped to deal with them.
• Because children are more sensitive to radiation, they should have a CT study only if it is essential for making a diagnosis and should not have repeated CT studies unless absolutely necessary.

source
http://www.radiologyinfo.org