Vitamin D Council Glossary

N-terminal atrial natriuretic peptide (NT-proANP)

A marker of salt sensitivity and predictor of congestive heart failure severity.

National Health and Nutrition Examination Surveys (NHANES)

Surveys designed to assess the health and nutritional status of adults and children in the United States through interviews and direct physical examinations.

National Hospital Discharge Survey (NHDS)

National probability survey designed to meet the need for information on characteristics of inpatients discharged from non-governmental, short-stay hospitals in the United States.

National Institute of Mental Health (NIMH)

Largest scientific organization in the world dedicated to research focused on the understanding, treatment, and prevention of mental disorders and the promotion of mental health.

National Institutes of Health (NIH)

Primary medical research center of the United States and part of the U.S. Department of Health and Human Services.

Natural killer cell (NK-cell,natural killer cells,NK-cells)

Cytotoxic lymphocyte that is a component of the innate immune system. NK-cells play a major role in host-rejection of tumors and viraly-infected cells.

Naturopath

Doctor who uses natural remedies such as herbs and foods rather than surgery or synthetic drugs.

Nephrologist

Physician who has been trained in the diagnosis and management of kidney disease.

Nephropathy

Damage to, or disease of, the kidney.

Nerve Growth Factor (NGF)

A compound that stimulates and directs nerve growth.

Nervous system

Very complex organ system that coordinates response to external stimuli. The nervous system is divided into two main subsystems, known as the central nervous system and the peripheral nervous system. The peripheral nervous system is further subdivided into the somatic nervous system and autonomic nervous system.

Neurite

A branching extension from the neuron cell body such as a dendrite or axon.

Neuroendocrine cells

Cells found in the hypothalamus that are involved in the regulation of functions in the entire body, such as the reproductive system and responses to stress, temperature, and sleep.

Neuroendocrine system

Bodily system comprised of organs and transmitter/receptor systems involved in communication between the nervous system and endocrine system.

Neuromodulator

Substance other than a neurotransmitter that is released by a neuron, transmitting information to other neurons and altering their activities.

Neuromuscular

Pertaining to both nerves and muscles.

Neuron

Any of the conducting cells of the nervous system.

Neurosteroid

Any steroid that is active in the brain.

Neurotransmitter

Chemical used to communicate signals between a neuron and another cell.

Neurotrophic factors (Neurotrophins)

Family of proteins responsible for the growth and survival of neurons during development and for maintaining adult neurons. Because neurotrophic factors are capable of making damaged neurons regrow their processes, they represent exciting possibilities for reversing devastating brain disorders including Alzheimer, Parkinson, and Lou Gehrig disease.

Nevus

Benign overgrowth of skin pigment forming cells called melanocytes on the skin surface.

Nitric oxide synthase (NOS)

One of the most regulated enzymes in biology, of which there are three known isoforms:

1. 
   
2. Neuronal NOS (nNOS or NOS1): located in nervous tissue in the central nervous system and peripheral nervous system, involved in cell communication.
   
3. Inducible NOS (iNOS or NOS2): located in the immune system and cardiovascular system, plays a role in immune defense against pathogens.
   
4. Endothelial NOS (eNOS or NOS3 or cNOS): generates nitric oxide in blood vessels, involved in regulation of vascular function.
   

No observable adverse effect level (NOAEL)

The highest tested dose or concentration of a substance at which no adverse effect is found in humans and animals.

Non-Hodgkin's Lymphoma (NHL)

Group of many, closely-related cancers affecting the lymphatic system that is divided into two major subgroups: B-cell lymphomas, which develop from abnormal B-lymphocytes, and T-cell lymphomas, which develop from abnormal T-lymphocytes.

Nuclear hormone receptor

Ligand-activated transcription factor that regulates gene expression by interacting with specific DNA sequences upstream of its target genes. See vitamin D receptor.

Nucleic acid (Nucleic acids)

Polymer of joined nucleotides whose function is to maintain, replicate, and express genetic information. The important nucleic acids are DNA and RNA.

Nucleotide (Nucleotides)

Nucleotides are the single units that make up nucleic acids such as RNA and DNA. They are literally the building blocks of life.