free radical


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radical

 [rad´ĭ-kal]
1. thorough or sweeping; directed to the cause or root of a morbid process.
2. a group of atoms that enters into and goes out of chemical combination without change and that forms one of the fundamental constituents of a molecule.
color radical chromophore.
free radical a radical that carries an unpaired electron; such radicals are extremely reactive, with a very short half-life.
oxygen radical a toxic metabolite of oxygen, such as superoxide or singlet oxygen, capable of damaging microorganisms and normal tissues.

free rad·i·cal

a radical in its (usually transient) uncombined state; an atom or atom group carrying an unpaired electron and no charge; e.g., hydroxyl and methyl
Free radicals may be involved as short-lived, highly active intermediates in various reactions in living tissue, notably in photosynthesis. The free radical nitric oxide, NO·, plays an important role in vasodilation.
Synonym(s): radical (4)

Free radicals are formed naturally as products of metabolic processes and can also be introduced from outside the body through smoking, inhaling environmental pollutants, or exposure to ultraviolet radiation. They interact readily with nearby molecules and may cause cellular damage, including genetic alterations. It has been theorized that they are involved in degenerative disorders such as Alzheimer dementia and parkinsonism, in plaque formation in atherosclerosis, and in cancer. Natural enzymes such as superoxide dismutase and peroxidase are thought to counteract free radicals, and there is evidence that many nutrients, including vitamins C and E and beta-carotene, also exert an antioxidant effect. see also antioxidant.

free radical

n.
An atom or group of atoms that has at least one unpaired electron and is therefore unstable and highly reactive. In animal tissues, free radicals can damage cells and are believed to accelerate the progression of cancer, cardiovascular disease, and age-related diseases.

free radical

a species with at least one unpaired electron. Oxygen is a stable diradical, but most other free radicals are unstable and react readily with other molecules.

free radical

Physiology
Any of a family of highly reactive molecules containing an unpaired electron in the outer orbital (e.g., the excited variants of O2). Free radicals cause random damage to structural proteins, enzymes, macromolecules and DNA; they play major roles in inflammation, hyperoxidation, post-ischaemic tissue damage, infarction and possibly also in carcinogenesis and tissue damage induced by organ transplantation. Free radical production is increased by cigarette smoking, radiation, UV light and chemical pollutants.

free radical

Physiology Any of a family of highly reactive molecules containing an unpaired electron in the outer orbital–eg, the excited variants of O2; FRs cause random damage to structural proteins, enzymes, macromolecules, DNA, playing major roles in inflammation, hyperoxidation, post-ischemic tissue damage, infarction, possibly also CA and tissue damage in transplants. See Antioxidants, Free radical scavenger, Free radical theory Vox populi Freed radical A paroled political polemicist.

free rad·i·cal

(frē rad'i-kăl)
A radical in its (usually transient) uncombined state; an atom or atom group carrying an unpaired electron and no charge. Free radicals may be involved as short-lived, highly active intermediates in various reactions in living tissue, notably in photosynthesis. The free radical nitric oxide, NO·, plays an important role in vasodilation.
Synonym(s): radical (4) .

free radical

an atom which has been ionized by radiation and from which electrons have been ejected as a result, leaving one or more unpaired electrons; such atoms react with other molecules e.g. DNA, and may cause damage or mutation.

Free radical

An unstable molecule that causes oxidative damage by stealing electrons from surrounding molecules, thereby disrupting activity in the body's cells.
Mentioned in: Smoking

free radical

transitory, potentially tissue-destructive atom

free rad·i·cal

(frē rad'i-kăl)
A radical in its (usually transient) uncombined state; an atom or atom group carrying an unpaired electron and no charge.
Synonym(s): radical (4) .

free radical,

n a compound with an unpaired electron or proton. It is unstable and reacts readily with other molecules.

radical

1. directed to the cause; going to the root or source of a morbid process.
2. a group of atoms that enters into and goes out of chemical combination without change and that forms one of the fundamental constituents of a molecule.

free radical
a radical, extremely reactive, and having a very short half-life (10−5 s or less in an aqueous solution), which carries an unpaired electron.
References in periodicals archive ?
The free radicals had no impact on the pups' immune responses or their ability to fight the flu.
Normally, we can keep pace with the production of free radicals as long as the system isn't overwhelmed, but under certain circumstances our own antioxidants get overpowered.
For instance, the immune system depends on them to help destroy bacteria but, when free radicals abound in excess, they are toxic.
Excessive amounts of free radicals have an aging effect on cells they come into contact with.
The physiology of the brain is finely tuned, so when the balance of free radicals to antioxidants gets out of whack, it may help to increase your levels of antioxidants to restore equilibrium," explains Greg Fricchione, MD, Director of the Benson-Henry Institute for Mind Body Medicine (BHI) at Massachusetts General Hospital (MGH).
Led by the international expert in organic chemistry Dr Anna Croft the team have started research into the powerful molecules known as free radicals.
He believes that once those genes are better protected they will not be so quickly mutated into the free radical death spiral.
In summary, this book is useful in providing a broad overview on free radicals in diseases and aging.
The year 1900 was marked by two events of great significance for the development of free radical chemistry, especially for Canada.
When these free radicals remove electrons from other atoms or molecules, the latter may themselves become free radicals -- and so the chain reaction goes on.
A natural byproduct of metabolism, the free radicals can react with important body molecules such as proteins and DNA, the chemical that makes up hereditary material.
Because of his extraordinary level of physical exertion, Fixx would have run a much higher risk of free radical damage than the average person.