Age Related Changes in Protein C Activity in Healthy Adult Males

ABSTRACT The age related changes on free plasma testosterone (T), dihydrotestosterone (DHT) and oestradiol (Oe2) were determined in 82 healthy adult males. Forty-six subjects were between 22 and 61 years of age (group I), 36 between 67 and 93 years (group II). The percentage of free, non protein bound hormone was determined by equilibrium dialysis of undiluted plasma against isotonic phosphate buffer at 37°C. Total hormone concentrations were measured by radioimmunoassay. The percentage of free T was 2.24 % (median), 1.65–3.42 (95 percentiles) in group I and 1.65 % (1.24–2.26) in group II. The percentage of free DHT decreased from 1.17 % (0.80–2.03) in group I to 0.83% (0.52–1.55) in group II. The decrease in % free Oe2 was only very small: group I = 2.49% (2.13–2.96), ad group II = 2.31% (1.95–3.17). The fall in free T by 43.3% from 12.2 ng/100 ml (6.74–25.0) in group I to 6.90 ng/ml (3.57–10.6) in group II was twice as high as that of total T, which decreased on an average by 20.6%. Free DHT decreased by 25.8 %: group I = 578 pg/100 ml (266–987), group II = 429 pg/100 ml (168–723), while total DHT was not significantly different between the two groups (–1.9%). Free Oe2 was increased in old age: group I = 42.4 pg/100 ml (26.0–69.4), group II = 55.7 pg/100 ml (35.8–118.9). The increase in free Oe2 by 31.4% was almost as high as that of the total Oe2 (46.9%).

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Age-related changes in fiber tracts in healthy adult brains: A generalized q-sampling and connectometry study

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.25949 ◽

2018 ◽

Vol 48 (2) ◽

pp. 369-381 ◽

Cited By ~ 2

Author(s):

Xiaojing Liu ◽

Xiaodong Gao ◽

Li Zhang ◽

Zilong Yuan ◽

Chen Zhang ◽

...

Keyword(s):

Healthy Adult ◽

Fiber Tracts ◽

Age Related ◽

Age Related Changes

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Comparison of Age-Related Changes in Prostaglandin E1 and Beta-Adrenergic Responsiveness of Vascular Smooth Muscle in Adult Males

Journal of Gerontology ◽

10.1093/geronj/44.1.m13 ◽

1989 ◽

Vol 44 (1) ◽

pp. M13-M17 ◽

Cited By ~ 20

Author(s):

A. N. Hiremath ◽

R. A. Pershe ◽

B. B. Hoffman ◽

T. F. Blaschke

Keyword(s):

Smooth Muscle ◽

Vascular Smooth Muscle ◽

Prostaglandin E1 ◽

Adult Males ◽

Beta Adrenergic ◽

Age Related ◽

Age Related Changes

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Age-related changes in the feedback regulation of gonadotrophin secretion in the immature and adult male rabbit

Acta Endocrinologica ◽

10.1530/acta.0.1000018 ◽

1982 ◽

Vol 100 (1) ◽

pp. 18-24 ◽

Cited By ~ 3

Author(s):

M. Berger ◽

Ch. Jean-Faucher ◽

M. De Turckheim ◽

G. Veyssière ◽

CI. Jean

Keyword(s):

Body Weight ◽

Negative Feedback ◽

Adult Male ◽

Feedback Regulation ◽

Adult Males ◽

Age Related ◽

Gonadotrophin Secretion ◽

Age Dependent ◽

Different Doses ◽

Age Related Changes

Abstract. Male rabbits were castrated at infantile (30 days), peripubertal (60 days) and adult (7–8 months) stages. Two different doses of testosterone were injected 10 days after castration (5 injections at 12 h intervals). Plasma LH and FSH were determined by RIA 1,5 and 10 days after castration and 1 h after the last injection of testosterone. The response of both gonadotrophins to castration was age-dependent. In 30 day old castrated males LH was not significantly modified and FSH had increased only 10 days after castration. In 60 day old and adult males FSH and LH levels were increased 24 h after castration and continued to rise as time progressed. For both gonadotrophins, the response of adult males to castration was higher than that of immature animals. At all stages studied, the highest dose of testosterone (250 μg/kg body weight) depressed post-castration LH and FSH levels. Twenty-five μg of testosterone per kg body weight was effective to depress LH levels only in 30 day old males, suggesting a change in the hypothalamic-pituitary unit to the negative feedback of androgens. These findings suggest that there are marked changes in the hypothalamic-pituitary unit around the beginning of the peripubertal stage. These changes could play a determinant role in the onset of puberty.

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Age-related changes of shape and flow dynamics in healthy adult aortas: A 4D flow MRI study

Journal of Magnetic Resonance Imaging ◽

10.1002/jmri.26210 ◽

2018 ◽

Vol 49 (1) ◽

pp. 90-100 ◽

Cited By ~ 5

Author(s):

Fraser M. Callaghan ◽

Paul Bannon ◽

Edward Barin ◽

David Celemajer ◽

Richmond Jeremy ◽

...

Keyword(s):

Healthy Adult ◽

Flow Dynamics ◽

4D Flow Mri ◽

4D Flow ◽

Age Related ◽

Flow Mri ◽

Mri Study ◽

Age Related Changes

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AGE RELATED CHANGES AND INTERRELATIONSHIPS BETWEEN PLASMA TESTOSTERONE, OESTRADIOL AND TESTOSTERONE-BINDING GLOBULIN IN NORMAL ADULT MALES

Acta Endocrinologica ◽

10.1530/acta.0.0740792 ◽

1973 ◽

Vol 74 (4) ◽

pp. 792-800 ◽

Cited By ~ 112

Author(s):

Karl M. Pirke ◽

Peter Doerr

Keyword(s):

Binding Capacity ◽

Plasma Testosterone ◽

Age Group ◽

Adult Males ◽

Total Plasma ◽

Biological Meaning ◽

Age Related ◽

Group I ◽

Peripheral Conversion ◽

Age Related Changes

ABSTRACT Testosterone (T), oestradiol-17β (Oe2) and binding capacity of the testosterone-binding globulin (TeBG) were measured in plasma of 84 adult males (22–90 years). The medians for age group I (22– 61 years, n = 50) were: T 545 ng/100 ml, Oe2 1.66 ng/100 ml, TeBG capacity 1.44 μg T/100 ml; the medians for age group II (67–90 years, n = 34) were: T 459 ng/100 ml, Oe2 2.56 ng/100 ml, TeBG capacity 2.05 μg T/100 ml. The decrease of T and the increase of Oe2 and TeBG capacity with age were significant. The significant correlation (P < 0.01) for either age group between T and Oe2 may be ascribed to a simultaneous secretion and/or a peripheral conversion of T to Oe2. The significant correlation (P < 0.05) between T and TeBG for the old age group probably reflects the comparatively high percentage of total plasma T bound to TeBG. The biological meaning of the correlation between Oe2 and TeBG is discussed.

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Protein C Activity in Healthy Volunteers - Influence of Age, Sex, Smoking and Oral Contraceptives

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649566 ◽

1993 ◽

Vol 70 (02) ◽

pp. 281-285 ◽

Cited By ~ 26

Author(s):

R C Tait ◽

Isobel D Walker ◽

S I A M Islam ◽

Frances McCall ◽

J A Conkie ◽

...

Keyword(s):

Protein C ◽

Smoking Habit ◽

Hormonal Contraceptive ◽

Reference Ranges ◽

Adult Males ◽

Amidolytic Activity ◽

Marked Rise ◽

Log Normal ◽

Log Normal Distribution ◽

Protein C Activity

SummaryInterpretation of protein C (PC) levels in a given individual has several limitations. A normal PC activity does not necessarily exclude a genetic deficiency nor can a reduced level confirm it. Measuring PC amidolytic activity in 9,648 healthy blood donors has allowed identification of demographic factors which cause variation in PC activity and further hinder interpretation. PC activity displays a log normal distribution and significant variation with age. This is most marked in young adult males when mean PC activity rises from 0.86 iu/ml (15–19 years) to 1.04 iu/ml (45–49 years; P <0.0001). Pre-menopausal females, who for most age ranges, have mean PC activity below their male contemporaries, show a less marked rise with age until the menopause when PC activity rises further. The use of hormonal contraceptive preparations is associated with an increase in mean PC activity of 0.05–0.08 iu/ml while smoking habit has no influence on PC activity.In view of these findings we strongly recommend the use of age and sex restricted reference ranges when interpreting PC activity.

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