The effect of glucagon on plasma cyclic AMP levels in young and elderly subjects

AGE ◽  
1984 ◽  
Vol 7 (3) ◽  
pp. 71-74 ◽  
Author(s):  
J. Stessman ◽  
R. Eliakim ◽  
R. P. Ebstein
Keyword(s):  
Cyclic Amp ◽  
Elderly Subjects ◽  
Young And Elderly Subjects

Ageing and the α2-adrenergic system of the platelet

1987 ◽  
Vol 73 (5) ◽  
pp. 507-513 ◽  
Author(s):  
Pamela B. Davis ◽  
Catherine Silski
Keyword(s):  
Cyclic Amp ◽  
The Elderly ◽  
Elderly Subjects ◽  
Adrenergic System ◽  
Scatchard Analysis ◽  
Adrenergic Agents ◽  
Α2 Adrenoceptor ◽  
Effector System ◽  
Potent Agonist ◽  
Young And Elderly Subjects

1. Platelets taken from healthy unmedicated subjects over 65 years of age display less inhibition of prostaglandin E1 (PGE1)-stimulated adenosine 3′:5′-cyclic monophosphate (cyclic AMP) synthesis by noradrenaline than do platelets taken from young adults aged 18–25 years (P < 0.03). The inhibition of cyclic AMP production by noradrenaline (10−5 mol/l) correlates negatively with age over the range 18–92 years (r = −0.338, n = 108, P < 0.005). The reduced cyclic AMP inhibition by noradrenaline in the elderly is not explained by basal cyclic AMP levels or degree of stimulation of platelets by PGE1, which do not differ between young and elderly subjects. The reduction itself is small, though, and cannot be demonstrated for a more potent agonist, adrenaline. 2. Despite the reduced noradrenaline response in the cyclic AMP system in the aged, platelet aggregation in response to α2-adrenergic agents is normal or even slightly increased. Aggregation responses to adrenergic agents correlate well with aggregation responses to adenosine 5′-diphosphate, suggesting that the effector system is a major determinant of the aggregation response. 3. α2-Adrenoceptor number measured by Scatchard analysis of equilibrium binding of [3H]yohimbine to platelet membranes is comparable in young and old subjects, and does not correlate with age. The KD for [3H]yohimbine does not correlate with age. The IC50 for noradrenaline displacing [3H]yohimbine is comparable in young and elderly subjects. Therefore the reduced inhibition of cyclic AMP production by noradrenaline in platelets from elderly subjects is not explained by changes in α2-adrenoceptor number, or agonist- or antagonist-binding properties, but may reside in the coupling of receptor to cyclase.

3D gait assessment in young and elderly subjects using foot-worn inertial sensors

2010 ◽  
Vol 43 (15) ◽  
pp. 2999-3006 ◽  
Author(s):  
Benoit Mariani ◽  
Constanze Hoskovec ◽  
Stephane Rochat ◽  
Christophe Büla ◽  
Julien Penders ◽  
...  
Keyword(s):  
Inertial Sensors ◽  
Elderly Subjects ◽  
Gait Assessment ◽  
Young And Elderly Subjects

Decreased Neutrophil Cyclic AMP Response to Isoprenaline Stimulation in the Elderly

1983 ◽  
Vol 65 (2) ◽  
pp. 155-157 ◽  
Author(s):  
T. G. Cotter ◽  
K. O'Malley
Keyword(s):  
Monoclonal Antibodies ◽  
Cyclic Amp ◽  
The Elderly ◽  
Population Heterogeneity ◽  
Elderly Subjects ◽  
Age Related ◽  
Significant Difference ◽  
Young Subjects ◽  
Drug Free

1. Neutrophils from drug-free elderly subjects produced approximately 50% less cyclic AMP in response to isoprenaline than did neutrophils from young subjects. A significant difference in basal cyclic AMP levels was also evident (elderly 2.8 ± 0.37; young 4.9 ± 0.36 pmol of cAMP/107 cells; P < 0.05). 2. With a range of anti-neutrophil monoclonal antibodies no evidence of age-related neutrophil population heterogeneity was found. 3. These findings indicate that the age-related decline in β-adrenoceptor responsiveness is not due to changes in the neutrophil population. 4. The present results support the hypothesis that there is a generalized decline in β-adrenoceptor-mediated responsiveness in the elderly.

THE EXCRETION OF LARGE VITAMIN C LOADS IN YOUNG AND ELDERLY SUBJECTS: AN ASCORBIC ACID TOLERANCE TEST

1988 ◽  
Vol 17 (1) ◽  
pp. 35-41 ◽  
Author(s):  
R. J. NEALE ◽  
H. LIM ◽  
JULIE TURNER ◽  
C. FREEMAN ◽  
J. R. KEMM
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Acid Tolerance ◽  
Tolerance Test ◽  
Elderly Subjects ◽  
Young And Elderly Subjects

Age Effects on Measures of Auditory Duration Discrimination

1994 ◽  
Vol 37 (3) ◽  
pp. 662-670 ◽  
Author(s):  
Peter J. Fitzgibbons ◽  
Sandra Gordon-Salant
Keyword(s):  
Hearing Loss ◽  
Stimulus Frequency ◽  
The Elderly ◽  
Duration Discrimination ◽  
Elderly Subjects ◽  
Hearing Sensitivity ◽  
Choice Procedure ◽  
Forced Choice Procedure ◽  
Tonal Stimuli ◽  
Young And Elderly Subjects

This study examined auditory temporal sensitivity in young adult and elderly listeners using psychophysical tasks that measured duration discrimination. Listeners in the experiments were divided into groups of young and elderly subjects with normal hearing sensitivity and with mild-to-moderate sloping sensorineural hearing loss. Temporal thresholds in all tasks were measured with an adaptive forced-choice procedure using tonal stimuli centered at 500 Hz and 4000 Hz. Difference limens for duration were measured for tone bursts (250 msec reference duration) and for silent intervals between tone bursts (250 msec and 6.4 msec reference durations). Results showed that the elderly listeners exhibited diminished duration discrimination for both tones and silent intervals when the reference duration was 250 msec. Hearing loss did not affect these results. Discrimination of the brief temporal gap (6.4 msec) was influenced by age and hearing loss, but these effects were not consistent across all listeners. Effects of stimulus frequency were not evident for most of the duration discrimination conditions.

Atrial natriuretic peptide suppresses osmostimulated vasopressin release in young and elderly humans

1991 ◽  
Vol 261 (2) ◽  
pp. E252-E256 ◽  
Author(s):  
B. A. Clark ◽  
D. Elahi ◽  
L. Fish ◽  
M. McAloon-Dyke ◽  
K. Davis ◽  
...  
Keyword(s):  
Atrial Natriuretic Peptide ◽  
Hypertonic Saline ◽  
Natriuretic Peptide ◽  
Serum Sodium ◽  
The Elderly ◽  
Sodium Concentration ◽  
Elderly Subjects ◽  
Vasopressin Release ◽  
Young And Elderly Subjects ◽  
Atrial Natriuretic

Atrial natriuretic peptide (ANP) may suppress vasopressin release, but the dynamics of this interaction as well as the influence of age have not been defined. We studied six or seven young (19-40 yr old) and seven elderly volunteers (65-83 yr old) under two circumstances: 1) after infusion of 5% saline (0.04 ml.kg-1.min-1) for 2 h and 2) after the same infusion given with simultaneous synthetic human ANP (0.05 micrograms.kg-1.min-1). Hypertonic saline alone produced a progressive rise in plasma vasopressin with increasing serum sodium. During hypertonic saline alone, vasopressin levels began to rise at an increment in serum sodium of 1.67 +/- 0.35 mM in the young and 1.43 +/- 0.32 mM in the elderly and rose linearly with increasing serum sodium. When ANP was infused with hypertonic saline (with peak ANP levels of approximately 1,000 pM), vasopressin levels began to rise at an increment in serum sodium of 4.43 +/- 0.67 mM in the young and 4.57 +/- 0.43 mM in the elderly (P less than 0.01 vs. saline alone). Furthermore, the vasopressin response for any given serum sodium was significantly reduced in both young and elderly subjects, resulting in a rightward displacement of the curve relating vasopressin response to sodium concentration (P less than 0.001). In conclusion, ANP not only suppresses vasopressin but raises the threshold for release of vasopressin in response to osmotic stimulation in both young and elderly individuals. High circulating ANP levels may be responsible in part for the suppression of vasopressin levels and water diuresis seen during states of volume expansion.

scholarly journals Reproducibility of tapping rhythm in young and elderly subjects

1991 ◽  
Vol 9 ◽  
pp. 21-26
Author(s):  
Tooru Nagasawa ◽  
Satoshi Kurata ◽  
Yasuhiko Abe ◽  
Yoshitaka Yuasa ◽  
Kazuhiro Tsuga ◽  
...  
Keyword(s):  
Elderly Subjects ◽  
Young And Elderly Subjects
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