VARIATION OF CORTISOL METABOLISM AS A CONTRIBUTING FACTOR TO DISCREPANCIES IN THE MEASUREMENT OF CORTISOL PRODUCTION RATE

1972 ◽  
Vol 70 (1) ◽  
pp. 89-96 ◽  
Author(s):  
M. J. Levell
Keyword(s):  
Production Rate ◽  
Isotope Dilution ◽  
Normal Subjects ◽  
Contributory Factor ◽  
Morning Dose ◽  
Production Rates ◽  
Evening Dose ◽  
Cortisol Metabolism

ABSTRACT Five normal subjects were given [14C] cortisol in the morning and [3H] cortisol in the evening, in both cases by mouth. The excretion of radioactivity in tetrahydrocortisol (THF) and tetrahydrocortisone (THE) was measured by a modified form of reverse isotope dilution. In 2 subjects, the ratio of isotopic THF/isotopic THE was higher after the evening dose than after the morning dose. In 1 subject the ratio decreased. In 2 subjects it did not change. Cortisol production rates calculated from THF were usually higher than those calculated from THE. The observed variations of metabolism were only a contributory factor to these discrepancies.

scholarly journals Altered Cortisol Metabolism in Polycystic Ovary Syndrome: Insulin Enhances 5α-Reduction But Not the Elevated Adrenal Steroid Production Rates

2003 ◽  
Vol 88 (12) ◽  
pp. 5907-5913 ◽  
Author(s):  
Tasoula Tsilchorozidou ◽  
John W. Honour ◽  
Gerard S. Conway
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Urinary Excretion ◽  
Production Rate ◽  
Polycystic Ovary ◽  
Resistance Index ◽  
Production Rates ◽  
Androgen Excess ◽  
Ovary Syndrome ◽  
Cortisol Metabolism ◽  
The Impact

Abstract Androgen excess in women with polycystic ovary syndrome (PCOS) may be ovarian and/or adrenal in origin, and one proposed contributing mechanism is altered cortisol metabolism. Increased peripheral metabolism of cortisol may occur by enhanced inactivation of cortisol by 5α-reductase (5α-R) or impaired reactivation of cortisol from cortisone by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) resulting in decreased negative feedback suppression of ACTH secretion maintaining normal plasma cortisol concentrations at the expense of androgen excess. We have tested whether any enzyme dysregulation was related to circulating insulin or androgen concentrations in women with PCOS and have sought to clarify their relationship with obesity. First, to avoid obesity-related effects on cortisol metabolism, 18 lean women with PCOS were compared with 19 lean controls who were closely matched for body mass index (BMI). Second, the impact of obesity was studied in a cross-section of 42 PCOS women of a broad range of BMI. We measured 24-h urinary excretion of steroid metabolites by gas chromatography/mass spectrometry and fasting metabolic and hormone profiles. Urinary excretion of androgens [androsterone (P = 0.003), etiocholanolone (P = 0.02), and C19 steroid sulfates (P = 0.009)], cortisone metabolites [tetrahydrocortisone (THE) (P = 0.02), α-cortolone (P < 0.001), β-cortol + β-cortolone (P < 0.001), cortolones (P < 0.001), and E metabolites (P < 0.001)], and TCM (P = 0.002) were raised in lean PCOS subjects when compared with controls. A significantly higher 5α-tetrahydrocortisol (5α-THF)/5β-THF ratio (P = 0.04) and a significantly lower α-THF + THF + α-cortol/THE + cortolones ratio (P = 0.01) were found in lean PCOS women compared with lean controls, indicating both enhanced 5α-R and reduced 11β-HSD1 activities. A decreased THE/cortolones ratio (P = 0.03) was also found in lean PCOS women compared with lean controls, indicating increased 20 α/β-HSD activity. In the group of 42 PCOS subjects, measures of 5α/5β reduction were positively correlated with the homeostasis model insulin resistance index (HOMA-R): α-THF/THF and HOMA-R (r = 0.34; P = 0.03), androsterone/etiocholanolone and HOMA-R (r = 0.32; P = 0.04), and total 5α /total 5β and HOMA-R (r = 0.37; P = 0.02). A positive correlation was also found between measures of 5α-R and BMI (r = 0.37; P = 0.02). No correlation was found between measures of 11β-HSD1 activity and indices of insulin sensitivity or BMI. We have demonstrated that there is an increased production rate of cortisol and androgens as measured in vivo in lean PCOS women. Insulin seems to enhance 5α reduction of steroids in PCOS but was not associated with the elevated cortisol production rate. The changes in 5α-R, 11β-HSD1, and 20α/β-HSD enzyme activities observed in PCOS may contribute to the increased production rates of cortisol and androgens, supporting the concept of a widespread dysregulation of steroid metabolism. This dysregulation does not seem to be the primary cause of PCOS because no correlation was found between serum androgen levels or urinary excretion of androgens with measurements of either 5α-R or 11β-HSD1 activities.

Secretion rate of dehydroepiandrosterone and dehydroepiandrosterone sulfate in benign essential hypertension as compared to normal subjects

1970 ◽  
Vol 48 (12) ◽  
pp. 1308-1313 ◽  
Author(s):  
A. Shao ◽  
W. Nowaczynski ◽  
O. Kuchel ◽  
J. Genest
Keyword(s):  
Essential Hypertension ◽  
Isotope Dilution ◽  
Normal Subjects ◽  
Dehydroepiandrosterone Sulfate ◽  
Secretion Rate ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
Hypertensive Patients ◽  
Double Isotope ◽  
Column Chromatographic

A study of the secretion rate of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S) in normal subjects and patients with benign essential hypertension by a double isotope dilution method showed a fivefold increase in the secretion rate of dehydroepiandrosterone (from 9.8 mg/day ± 3.1 mg/day S.D. to 52.0 mg/day ± 15.5 mg/day S.D.), and a sixfold increase of dehydroepiandrosterone sulfate in hypertensive patients (from 10.7 mg/day ± 2.9 mg/day S.D. to 60.7 mg/day ± 18.6 mg/day S.D.). This study was carried out following the administration of 14C-labelled DHEA and 3H-labelled DHEA-S and involved an initial column chromatographic separation of urinary DHEA-glucuronide and sulfate.

scholarly journals Quantifying the controls on potential soil production rates: a case study of the San Gabriel Mountains, California

2017 ◽  
Vol 5 (3) ◽  
pp. 479-492 ◽  
Author(s):  
Jon D. Pelletier
Keyword(s):  
Production Rate ◽  
Small Subset ◽  
Published Data ◽  
Production Rates ◽  
Soil Thickness ◽  
Cold Temperatures ◽  
San Gabriel Mountains ◽  
Erosion Rates ◽  
Soil Production ◽  
Average Slope

Abstract. The potential soil production rate, i.e., the upper limit at which bedrock can be converted into transportable material, limits how fast erosion can occur in mountain ranges in the absence of widespread landsliding in bedrock or intact regolith. Traditionally, the potential soil production rate has been considered to be solely dependent on climate and rock characteristics. Data from the San Gabriel Mountains of California, however, suggest that topographic steepness may also influence potential soil production rates. In this paper I test the hypothesis that topographically induced stress opening of preexisting fractures in the bedrock or intact regolith beneath hillslopes of the San Gabriel Mountains increases potential soil production rates in steep portions of the range. A mathematical model for this process predicts a relationship between potential soil production rates and average slope consistent with published data. Once the effects of average slope are accounted for, a small subset of the data suggests that cold temperatures may limit soil production rates at the highest elevations of the range due to the influence of temperature on vegetation growth. These results suggest that climate and rock characteristics may be the sole controls on potential soil production rates as traditionally assumed but that the porosity of bedrock or intact regolith may evolve with topographic steepness in a way that enhances the persistence of soil cover in compressive-stress environments. I develop an empirical equation that relates potential soil production rates in the San Gabriel Mountains to the average slope and a climatic index that accounts for temperature limitations on soil production rates at high elevations. Assuming a balance between soil production and erosion rates on the hillslope scale, I illustrate the interrelationships among potential soil production rates, soil thickness, erosion rates, and topographic steepness that result from the feedbacks among geomorphic, geophysical, and pedogenic processes in the San Gabriel Mountains.

scholarly journals Aleutian island arc magma production rates and mechanisms

2019 ◽  
Author(s):  
Yongliang Bai ◽  
Diya Zhang ◽  
Dongdong Dong ◽  
Shiguo Wu ◽  
Zhenjie Wang
Keyword(s):  
High Temperature ◽  
Production Rate ◽  
Island Arc ◽  
Mantle Melting ◽  
Fracture Zones ◽  
Seismic Profiles ◽  
Production Rates ◽  
Aleutian Arc ◽  
Slab Dehydration ◽  
Arc Magma

Abstract. The variation in island arc magma production rates and their influencing mechanisms are of great significance since island arc magma is considered a main source of continental crust growth. The island arc magma directly originates from the molten mantle wedge, and the mantle melting is driven by fluids or melts from the subducted slab. Slab dehydration flux mainly depends on the slab thermal structures, and subducted slab melting requires a sufficiently high temperature. For the Aleutian subduction system, the subducted Pacific Plate has diverse thermal structures due to the existing fracture zones, ridges and slab window, so it is an ideal region for arc magma production rate research. However, the previous estimations are based on seismic profiles that only provide magma production rates at specific regions of the Aleutian arc, and these results are controversial. Here, we design a magma production rate estimation method based on gravity inversion constrained by deep seismic profiles. The first overview map of magma production rates along the Aleutian arc strike demonstrates that the magma production rates have the same trend as the slab dips, and the peaks correspond to the subduction of the fracture zones and ridges. The potential mechanisms for these correlations are as follows: (1) Slab water flux at subarc depths increases with increasing slab dip. More fluid flux would induce more mantle melting, and so the arc magma production rates are increased. (2) Water-rich serpentine is formed by hydrothermal alteration on or near the surface of the subducted slab when there are fracture zones. Serpentine decomposition at a depth of 80–120 km releases fluids in addition to the fluids released during normal slab dehydration. Therefore, more fluids induce more mantle melting and correspond a larger magma production rate. (3) The slab located in the Emperor Seamounts has a relatively high temperature and is also weak, so its melting is easier. Similarly, more slab melt means more mantle melt and a higher island arc magma production rate.

Volatile fatty acids and sulfide in pressure mains

1995 ◽  
Vol 31 (7) ◽  
pp. 169-179 ◽  
Author(s):  
T. Hvitved-Jacobsen ◽  
K. Raunkjær ◽  
P. H. Nielsen
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Production Rate ◽  
Volatile Fatty Acids ◽  
Production Rates ◽  
Net Production ◽  
Toc Removal ◽  
Sulfide Production ◽  
Transformation Of Organic Matter ◽  
High Sulfide

The main objective was to study the anaerobic transformation of organic matter and sulfide production during wastewater transportation. Emphasis was on the transformation of easily biodegradable organic matter in terms of volatile fatty acids (VFA). Samples from two intercepting pressure mains located in the Northern part of Jutland, Denmark, were taken. The concentration of VFA in the wastewater varied considerably during day and night, being typically between 5 and 50 g/m3. A net production as well as a net removal of VFA was seen during transportation in the pressure mains probably depending on the quality and quantity of the organic matter. Typically 85% of the VFA was acetate and 10% propionate; the remainder was formate, n-butyrate and iso-butyrate. Observed sulfide production rates from the sewer biofilms were typically 0.05 and 0.005 g S/m2 h at 12 and 4 °C, respectively. A high sulfide production rate corresponded with a high VFA concentration. TOC removal was observed in the pressure mains.

Production of volatile fatty acids in the sheep caecum

1969 ◽  
Vol 20 (3) ◽  
pp. 491 ◽  
Author(s):  
GJ Faichney
Keyword(s):  
Fatty Acids ◽  
Steady State ◽  
Fatty Acid ◽  
Production Rate ◽  
Energy Intake ◽  
Isotope Dilution ◽  
Volatile Fatty Acids ◽  
Specific Activity ◽  
Total Production ◽  
Digestible Energy

Acetic, propionic, and butyric acids labelled with 14C were infused into the caecum of continuously fed sheep. The specific activity of the volatile fatty acids (VFA) in the caecum was determined at intervals during the infusion. The production rate was calculated by isotope dilution from the results of those experiments in which steady state conditions were obtained. Substantial interconversions occurred between the fatty acid fractions. The total production of VFA was about 440 mmoles/day, equivalent to 125 kcal/day or 5.3% of the animal's digestible energy intake.

Manual Release Contracting: Production Rates, Costs, and Future

1990 ◽  
Vol 5 (3) ◽  
pp. 83-85 ◽  
Author(s):  
Gary O. Fiddler ◽  
Philip M. McDonald
Keyword(s):  
Production Rate ◽  
Land Management ◽  
Average Cost ◽  
National Forests ◽  
Bureau Of Land Management ◽  
Production Rates ◽  
The West ◽  
Competing Vegetation ◽  
Service Contracts

Abstract Manual release, primarily accomplished through the use of service contracts, is increasingly used by silviculturists for controlling competing vegetation in the West, particularly in California. Over 60 recent manual release contracts on four National Forests and one Bureau of Land Management Resource Area in California were analyzed for production rate and cost relationships. Mean number of acres completed per workday was 0.11-0.50 and the average cost of release was $174-$310 per acre. Grubbing or cutting costs were $0.44-$0.86 per seedling regardless of radius treated. Cutting and grubbing combined cost $0.63-$0.71 per seedling for 3-5 ft radii, and $1.19 for a 6-ft radius. The increased costs resulting from more realistic bidding and the projected unavailability of crews to do the work mean that many acres needing manual release will go untreated. West. J. Appl. For. 5(3):83-85, July 1990.

Study of Methane Production by High Temperature Anaerobic Fermentation of Chicken Manure and Stalks

2020 ◽  
Vol 14 (4) ◽  
pp. 551-557
Author(s):  
Yongku Li ◽  
Xiaomin Hu ◽  
Lei Feng
Keyword(s):  
High Temperature ◽  
Anaerobic Digestion ◽  
Production Rate ◽  
Methane Production ◽  
Anaerobic Fermentation ◽  
Biogas Production ◽  
Gas Production ◽  
Chicken Manure ◽  
Biogas Slurry ◽  
Production Rates

The changing parameters, as the biogas production rate, the methane production rate, the cumulative biogas amount, the cumulative methane amount, the biogas composition, pH etc. in high temperature anaerobic fermentation of chicken manure and stalks were analyzed by experiments with different mass ratios of chicken manure or livestock manure and stalks with a high C/N ratio. The methane production mechanism of high temperature anaerobic digestion of chicken manure and stalks was discussed in detail. It showed that not only the biogas production rates but also the methane production rates of R1–R7 demonstrated the trend of initial increase and then decrease after 50 d of high temperature anaerobic digestion. Besides, the gas production of R1 with pure chicken manure stopped on the 30th d of the reaction. The gas production of other groups R2–R7 also stopped on the corresponding 34th, 36th, 36th, 37th, 37th, and 37th day, respectively. At the end of the reaction, the cumulative biogas amounts and the cumulative methane amounts of R1–R7 were 411.58 and 269.54, 459.91 and 314.41, 425.32 and 294.11, 401.85 and 272.54, 382.63 and 257.07, 363.04 and 218.16, and 257.15 and 160.10 N ml/(g VS). The biogas slurry pH of R1–R7 all demonstrated a trend of initial decrease and then increase, e. g., pH of R2 reached the minimum of 5.94 on the 5th day. pH values of other groups were between 6.01 and 6.39. After the addition of 4 g of sodium bicarbonate on the 7th day, biogas slurry pH of R1–R7 all increased. pH was maintained between 7.16 and 7.44 until the end of the reaction.

Determination of the urinary cortisol production rate using (1,2,3,4-13C)cortisol. Isotope dilution analyses at very small enrichments

1987 ◽  
Vol 14 (2) ◽  
pp. 73-82 ◽  
Author(s):  
T. E. Chapman ◽  
G. P. B. Kraan ◽  
N. M. Drayer ◽  
G. T. Nagel ◽  
B. G. Wolthers
Keyword(s):  
Production Rate ◽  
Isotope Dilution ◽  
Urinary Cortisol
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