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Biomedical subjects

I Stolarek

Publications and source records attributed to I Stolarek.

3 recordsLinked to original sources

Biological variation of urinary N-acetyl-beta-D-glucosaminidase: practical and clinical implications.

The analytical, within-subject, and between-subject components of variation of N-acetyl-beta-D-glucosaminidase (NAG) were estimated from duplicate assays of 10 timed first morning and 10 untimed urine specimens collected from each of 15 ostensibly healthy individuals. Results were expressed in terms of activity, NAG/creatinine ratio, and excretion rate. Current analytical methods can achieve desirable performance standards. NAG has little individuality, and conventional population-based reference intervals are therefore useful. In view of the practicability and relatively low within-subject variation, for routine clinical purposes we prefer assay of NAG in first morning urine, expressing the results in terms of activity. Using the results of assays of different specimens, we found that the correlation between urinary albumin and NAG varied considerably, owing to the large intrinsic variability of both analytes; this might explain previous conflicting results.

Acetylglucosaminidase

Physiological changes due to age. Implications for cardiovascular drug therapy.

Cardiovascular disease is the single largest cause of death in the elderly. Many of the published studies concerning the physiology and pharmacology of the aging cardiovascular system are seriously flawed. Problems include failure to measure the drug bioavailability and the selection of subjects with overt or subclinical disease. With exercise, the rise in heart rate is inversely proportional to age and maximum heart rate is reduced. Baroreceptor reflex activity appears to decline with age. Cardiac output is maintained in the elderly, with a slower heart rate and a greater stroke volume than in the young. Plasma noradrenaline (norepinephrine) levels increase in the elderly but there is no change in the sensitivity of the vasoconstrictor alpha 1-adrenoceptor. There is evidence for a decline in the activity of the vasodilator beta 2-adrenoceptor with age. It is difficult to make general rules about the effect of aging on the disposition and elimination of drugs. Each drug must be tested separately.

Aging