| aging, premature | Changes in the organism associated with senescence, occurring at an accelerated rate. (12 Dec 1998) |
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| aging | The gradual changes in the structure and function of humans and animals that occur with the passage of time, that do not result from disease or other gross accidents, and that eventually lead to the increased probability of death as the person or animal grows older. It does not apply to microorganisms. (12 Dec 1998) |
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| cell aging | The decrease in the cell's ability to proliferate with the passing of time. Each cell is programmed for a certain number of cell divisions and at the end of that time proliferation halts. The cell enters a quiescent state after which it experiences cell death via the process of apoptosis. (12 Dec 1998) |
| clonal aging | The deterioration in successive generations of a clone; thus paramecia and other simple forms, if allowed to reproduce asexually for a number of generations, invariably undergo deterioration, the characters of each group of descendants progressively departing from those of the original sexually produced ancestor. (05 Mar 2000) |
| skin aging | The process of aging due to changes in the structure and elasticity of the skin over time. It may be a part of physiological aging or it may be due to the effects of ultraviolet radiation, usually through exposure to sunlight. (12 Dec 1998) |
| erythrocyte aging | Senescence of the red blood cell. Lacking the organelles that make protein synthesis possible, the mature erythrocyte is incapable of self-repair, reproduction, and carrying out certain functions performed by other cells. This limits the average life span of an erythrocyte to 120 days. (12 Dec 1998) |
| atrial premature complexes | Premature contractions of the heart arising from an ectopic atrial focus. With ventricular premature complexes, they represent one of the most common causes of irregular pulse. They are more apt to occur if there is atrial or conduction system disease such as left atrial enlargement in mitral stenosis. In community prospective studies, atrial premature complexes are not related to sudden death, as are ventricular premature beats in coronary disease. (12 Dec 1998) |
| atrial premature contraction | <cardiology> An premature heartbeat of atrial origin. Generally nonserious and typically exacerbated by stimulant use (for example alcohol, decongestants, caffeine, nicotine). (27 Sep 1997) |
| cardiac complexes, premature | Premature contractions of the heart that are independent of the normal rhythm and arise in response to an impulse in some part of the heart other than the sinoatrial node. (12 Dec 1998) |
| ventricular premature complexes | Premature contractions of the ventricle, the most common of all arrhythmias. In the absence of heart disease, they are not of great clinical significance, but in patients with coronary disease, they represent a constant danger of ventricular tachycardia or fibrillation and sudden death. The longer-term prognosis for asymptomatic, healthy subjects with frequent and complex ectopy is similar to that for the healthy united states population. (12 Dec 1998) |
| retinopapillitis of premature infants | <ophthalmology, paediatrics> A bilateral retinopathy occurring in premature infants treated with excessively high concentrations of oxygen, characterised by vascular dilatation, proliferation, and tortuosity, oedema, and retinal detachment, with ultimate conversion of the retina into a fibrous mass that can be seen as a dense retrolental membrane. Usually growth of the eye is arrested and may result in microophthalmia, and blindness may occur. (03 Jul 1999) |
| menopause, premature | Premature failure of ovulation associated with the permanent disappearance of oocytes and follicles from the ovary in women under the age of 40. If failure occurs while follicles are still present, the condition is called premature ovarian failure (ovarian failure, premature). (12 Dec 1998) |
| premature | 1. Occurring before the proper time. 2. <paediatrics> A premature infant. Origin: L. Praematurus = early ripe (18 Nov 1997) |
| premature beat | A premature contraction of the heart that is independent of the normal rhythm and arises in response to an impulse in some part of the heart other than the sinoatrial node. Synonym: premature beat. (18 Nov 1997) |
| premature contact | A condition of tooth contact's which diverts the mandible from a normal path of closure to centric jaw relation. Synonym: cuspal interference, interceptive occlusal contact, premature contact. (05 Mar 2000) |
| premature contraction | A premature contraction of the heart that is independent of the normal rhythm and arises in response to an impulse in some part of the heart other than the sinoatrial node. Synonym: premature beat. (18 Nov 1997) |