Nadir
The lowest level to which viral load (the amount of HIV in the blood) falls after a person starts anti-HIV treatment. Also refers to the lowest CD4 count a person reaches during HIV infection.

National Cancer Institute (NCI)
A institute of the National Institutes of Health (NIH) and the U.S. government's principal agency for cancer research and training. This institute provides health information and supports programs focusing on the causes, diagnosis, prevention, and treatment of cancer; rehabilitation from cancer; and the continuing care of cancer patients and the families of cancer patients. http://www.nci.nih.gov

National Institute of Allergy and Infectious Diseases (NIAID)
An institute of the National Institutes of Health (NIH) that conducts and funds research to better understand, treat, and prevent infectious, immunologic, and allergic diseases. http://www3.niaid.nih.gov

National Institutes of Health (NIH)
A multi-institute agency of the U.S. Department of Health and Human Services (DHHS). NIH conducts research in its own laboratories and funds research in universities, medical schools, hospitals, and other research institutions throughout the United States and abroad. http://www.nih.gov

National Library of Medicine (NLM)
An institute of the National Institutes of Health (NIH) and the world's largest medical library. NLM collects materials in all areas of biomedicine and health care and is involved in biomedical aspects of other fields such as technology and the social sciences. http://www.nlm.nih.gov

National Prevention Information Network (NPIN)
A national reference, referral, and distribution service for information on HIV/AIDS, other sexual transmitted diseases (STDs), and tuberculosis (TB), sponsored by the Centers for Disease Control and Prevention (CDC). http://www.cdcnpin.org

Natural History Study
A study designed to investigate the natural development of a disease or condition over time.

Natural Killer Cells (NK Cells)
White blood cells that are able to kill tumor cells and cells infected with viruses or other foreign invaders.

NCI
See: National Cancer Institute

NDA
See: New Drug Application

Neonatal
The time period from birth through the first 4 weeks after birth.

Neoplasm
Also called tumor. Any new, abnormal growth of tissue. Neoplasms may be benign (not cancerous) or malignant (cancerous).

Nephritis
Inflammation of the kidney that can occur as a side effect of some anti-HIV drugs.

Nephrotoxic
Toxic or destructive to the kidneys.

Neuralgia
Sharp, shooting pain along a nerve pathway.

Neuropathy
A disorder that occurs when nerve cells are damaged. Symptoms range from a tingling sensation or numbness in the toes and fingers to paralysis. Neuropathy can occur as a result of HIV infection or as a side effect of certain anti-HIV drugs.
See Also:   Peripheral Neuropathy

Neutropenia
A lower than normal number of neutrophils (a type of white blood cell) in the blood. Moderate to severe neutropenia can increase the chance of developing bacterial infections. Neutropenia may occur as a result of HIV infection or as a side effect of some anti-HIV drugs.
See Also:   Neutrophil

Neutrophil
A type of white blood cell that can engulf and kill foreign invaders such as bacteria.

New Drug Application (NDA)
An application submitted by a drug manufacturer to the Food and Drug Administration (FDA) for a license to market and sell a particular drug in the United States. The drug manufactor files an NDA after information from clinical trials is available for FDA review.
See Also:   Investigational New Drug Application

NHL
See: Non-Hodgkin's Lymphoma

NIAID
See: National Institute of Allergy and Infectious Diseases

NIH
See: National Institutes of Health

NK Cells
See: Natural Killer Cells

NLM
See: National Library of Medicine

NNRTIs
See: Non-Nucleoside Reverse Transcriptase Inhibitors

Non-Hodgkin's Lymphoma (NHL)
A cancer of lymphoid tissue that can affect the lymph nodes, spleen, bone marrow, and other organs of the immune system. This type of cancer typically develops in people with weakened immune systems, including organ transplant recipients and people with HIV or AIDS.
See Also:   Lymphoma
                   Hodgkin's Lymphoma

Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs)
A class of anti-HIV drugs that bind to and disable HIV-1's reverse transcriptase enzyme, a protein that HIV needs to make more copies of itself. Without functional reverse transcriptase, HIV replication is halted. Current NNRTI medications are only effective against HIV-1 and not against HIV-2.
See Also:   Reverse Transcriptase

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)
A class of drugs that can reduce inflammation, swelling, stiffness, and joint pain. They are used to treat arthritis and mild to moderate pain. Some common NSAIDs are aspirin and ibuprofen.

NPIN
See: National Prevention Information Network

NSAIDs
See: Non-Steroidal Anti-Inflammatory Drugs

Nucleic Acid
Chemical structure that stores genetic information. There are two types of nucleic acid, DNA and RNA. Human genetic information is stored as DNA, while HIV's genetic information can be stored as both DNA and RNA.
See Also:   Deoxyribonucleic Acid
                   Ribonucleic Acid

Nucleic Acid Test
A laboratory test that can detect very small amounts of specific genetic material in blood, plasma, or other tissue. This test can detect several types of viruses and is used to screen blood from blood donors.

Nucleoside
A precursor to a building block of DNA or RNA. Nucleosides must be chemically changed into nucleotides before they can be used to make DNA or RNA.
See Also:   Deoxyribonucleic Acid
                   Ribonucleic Acid
                   Nucleotide

Nucleoside Analogue Reverse Transcriptase Inhibitor
A class of anti-HIV drug. Nucleoside analogues are faulty versions of the building blocks necessary for HIV reproduction. When HIV's reverse transcriptase enzyme uses a nucleoside analogue instead of a normal nucleoside, reproduction of the virus's genetic material is halted. Also called nucleoside analogues or "nukes."
See Also:   Nucleoside
                   Reverse Transcriptase

Nucleotide
A building block of DNA or RNA, the chemical structures that store genetic information.
See Also:   Deoxyribonucleic Acid
                   Ribonucleic Acid

Nucleotide Analogue Reverse Transcriptase Inhibitor
A class of anti-HIV drug. Nucleotide analogues are faulty versions of the building blocks necessary for HIV reproduction. When HIV's reverse transcriptase enzyme uses a nucleotide analogue instead of a normal nucleotide, reproduction of the virus's genetic material is halted. Although technically different from nucleoside analogues, nucleotide analogues work in the same way. Also called nucleotide analogues or "nukes."
See Also:   Nucleotide
                   Reverse Transcriptase

Nucleus
The part of a cell that contains the organism's genetic information.

Nukes
Slang term for nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs).
See Also:   Nucleoside Analogue Reverse Transcriptase Inhibitor