Cell metabolic activity in acromegaly: a microcalorimetric study of lymphocyte metabolism

1990 ◽  
Vol 122 (4) ◽  
pp. 422-426 ◽  
Author(s):  
Stig Valdemarsson ◽  
Julie Ikomi-Kumm ◽  
Mario Monti
Keyword(s):  
Growth Hormone ◽  
Production Rate ◽  
Metabolic Activity ◽  
Heat Production ◽  
Disease Process ◽  
Serum Levels ◽  
Clinical Activity ◽  
Clinical Impression ◽  
Cell Metabolic Activity ◽  
Heat Production Rate

Abstract. A discrepancy between the clinical impression of disease activity and basal serum levels of growth hormone is often seen in patients with acromegaly. A slightly better relation has been found to serum levels of IGF-I, but a technique for evaluation of cell metabolic activity in this disease is still missing. For this purpose we used microcalorimetry to determine heat production rate in lymphocytes from 15 patients with acromegaly. The mean heat production rate was 2.90±0.15 pW/cell, significantly higher than in 13 healthy subjects, 2.31±0.12 pW/cell (p<0.01). Heat production rates did not correlate significantly with basal growth hormone levels, but increased, in a statistically significant manner (p<0.001), in parallel with the score index used to evaluate the clinical activity of the disease. Using the technique of microcalorimetry we could thus demonstrate an increased metabolic activity at a cellular level in patients with acromegaly, a finding that is in accordance with the view that an increased cell metabolic activity is a component of the disease process in acromegaly.

Increased ratio between anaerobic and aerobic metabolism in lymphocytes from hyperthyroid patients

1994 ◽  
Vol 130 (3) ◽  
pp. 276-280 ◽  
Author(s):  
Stig Valdemarsson ◽  
Mario Monti
Keyword(s):  
Oxygen Consumption ◽  
Production Rate ◽  
Metabolic Activity ◽  
Heat Production ◽  
Aerobic Metabolism ◽  
University Hospital ◽  
Control Group ◽  
Total Lymphocyte ◽  
Heat Production Rate ◽  
Hyperthyroid Patients

Valdemarsson S, Monti M. Increased ratio between anaerobic and aerobic metabolism in lymphocytes from hyperthyroid patients. Eur J Endocrinol 1994;130:276–80. ISSN 0804–4643 While an increased oxygen consumption is accepted as one consequence of hyperthyroidism, only few data are available on the role of anaerobic processes for the increased metabolic activity in this disease. In this study we evaluated the relative importance of anaerobic and aerobic metabolism for the metabolic activity in lymphocytes from patients before and after treatment for hyperthyroidism. Total lymphocyte heat production rate (P), reflecting total cell metabolic activity, was determined in a plasma lymphocyte suspension using direct microcalorimetry. The contribution from aerobic metabolism (O2 – P) was calculated from the product of the lymphocyte oxygen consumption rate and the enthalpy change for glucose combustion, and the anaerobic contribution as the difference between P and O2 – P. The total lymphocyte heat production rate P was 3.37 ± 0.25 (sem) pW/cell (N = 11) before and 2.50 ± 0.11 pW/cell (N = 10) after treatment for hyperthyroidism (p < 0.01) as compared to 2.32 ± 0.10 pW/cell in a control group (N = 18). The aerobic component O2 – P amounted to 1.83 ± 0.11 pW/cell in the patient group before and 1.83 ± 0.08 pW/cell after treatment and to 1.71 ± 0.16 pW/cell in 10 controls. Out of P, the O2 – P component corresponded to 56.8 ± 4.4% in the hyperthyroid state and to 73.7 ± 3.2% after treatment (p < 0.01) as compared to 73.4 ± 4.4% in the 10 euthyroid controls. It was concluded that the increased metabolic activity demonstrated in lymphocytes from hyperthyroid patients cannot be explained by an increased oxygen-dependent consumption. This suggests that cell function may be comparatively more dependent on anaerobic metabolism during thyroid hormone excess and that adenosine triphosphate generation thereby has to be supplied through an increased metabolism of energy-rich substrates along anaerobic metabolic pathways. Stig Valdemarsson, Department of Internal Medicine, Lund University Hospital, S-221 85 Lund, Sweden

Anthropogenic Heat Release Into the Environment

2012 ◽  
Author(s):  
Kaufui V. Wong ◽  
Yading Dai ◽  
Brian Paul
Keyword(s):  
Climate Change ◽  
Solar Radiation ◽  
Production Rate ◽  
Heat Production ◽  
Domestic Animals ◽  
Anthropogenic Heat ◽  
Net Energy ◽  
The Earth ◽  
Heat Production Rate ◽  
Energy Dissipated

This work is intended to systematically study an inventory of the anthropogenic heat produced. This research strives to present a better estimate of the energy generated by humans and human activities, and compare this estimate to the significant energy quantity with respect to climate change. Because the Top of Atmosphere (TOA) net energy flux was found to be 0.85±0.15 W/m2 the planet is out of energy balance, as studied by the group from NASA in 2005. The Earth is estimated to gain 431 TW from this energy imbalance. This number is the significant heat quantity to consider when studying global climate change, and not the 78,300 TW, the absorbed part of the primary solar radiation reaching the Earth’s surface, as commonly cited and used at present in the literature. Based on energy supplied to the boilers (in the Rankine cycle) of at least 13 TW, body energy dissipated by 7 billion people and their domestic animals, the value of the total world anthropogenic heat production rate is 15.26 TW or 3.5% of the energy gain by the Earth. Based on world energy consumption and the energy dissipated by 7 billion people and their domestic animals, the value of the total world anthropogenic heat production rate is 19.7 TW or about 5% of the energy gain by the Earth. These numbers are significantly different from 13 TW. More importantly, the figures are 3.5 to 5% of the net energy gained by the Earth, and hence significant. The quantity is not 0.017% of the absorbed part of the main solar radiation reaching the Earth’s surface and negligible.

scholarly journals Thermo-hydro-mechanical modelling study of heat extraction and flow processes in enhanced geothermal systems

2021 ◽  
Vol 54 ◽  
pp. 229-240
Author(s):  
Dejian Zhou ◽  
Alexandru Tatomir ◽  
Martin Sauter
Keyword(s):  
Production Rate ◽  
Flow Rate ◽  
Heat Production ◽  
Analytical Solutions ◽  
Pressure Difference ◽  
Heat Extraction ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Fracture Zones ◽  
Heat Production Rate

Abstract. Enhanced Geothermal Systems (EGS) are widely used in the development and application of geothermal energy production. They usually consist of two deep boreholes (well doublet) circulation systems, with hot water being abstracted, passed through a heat exchanger, and reinjected into the geothermal reservoir. Recently, simple analytical solutions have been proposed to estimate water pressure at the abstraction borehole. Nevertheless, these methods do not consider the influence of complex geometrical fracture patterns and the effects of the coupled thermal and mechanical processes. In this study, we implemented a coupled thermo-hydro-mechanical (THM) model to simulate the processes of heat extraction, reservoir deformation, and groundwater flow in the fractured rock reservoir. The THM model is validated with analytical solutions and existing published results. The results from the systems of single fracture zone and multi-fracture zones are investigated and compared. It shows that the growth of the number and spacing of fracture zones can effectively decrease the pore pressure difference between injection and abstraction wells; it also increases the production temperature at the abstraction, the service life-spans, and heat production rate of the geothermal reservoirs. Furthermore, the sensitivity analysis on the flow rate is also implemented. It is observed that a larger flow rate leads to a higher abstraction temperature and heat production rate at the end of the simulation, but the pressure difference may become lower.

The global joule heat production rate and the AE index

1985 ◽  
Vol 33 (3) ◽  
pp. 279-281 ◽  
Author(s):  
Sun Wei ◽  
B.-H. Ahn ◽  
S.-I. Akasofu
Keyword(s):  
Production Rate ◽  
Heat Production ◽  
Joule Heat ◽  
Ae Index ◽  
Heat Production Rate

Thyroid hormones and thermogenesis: A microcalorimetric study of overall cell metabolism in lymphocytes from patients with different degrees of thyroid dysfunction

1990 ◽  
Vol 123 (2) ◽  
pp. 155-160 ◽  
Author(s):  
Stig Valdemarsson ◽  
Julie Ikomi-Kumm ◽  
Mario Monti
Keyword(s):  
Thyroid Hormones ◽  
Production Rate ◽  
Heat Production ◽  
Subclinical Hypothyroidism ◽  
Thyroid Dysfunction ◽  
Control Group ◽  
Subclinical Hyperthyroidism ◽  
Significant Difference ◽  
Heat Production Rate ◽  
Serum Tsh

Abstract. We used microcalorimetry to measure lymphocyte heat production rate in patients with clinical and laboratoy hyperthyroidism (serum TSH ↓, serum FT4 ↑, serum FT3 ↑ ), subclinical hyperthyroidism (serum TSH ↓, serum FT4 ↑, serum FT3=), and subclinical hypothyroidism (serum TSH ↑, serum FT4 ↓, serum FT3=) compared with healthy controls (N= 13). The lymphocyte heat production rate was significantly correlated to the free thyroxine level (r=0.53, p<0.01) and to the free triiodothyronine level (r=0.51, p<0.01) when calculated from pooled data for the three patients groups. The hyperthyroid patients (N = 8) had a significantly increased lymphocyte heat production rate, 3.43±0.25 pW/cell, as compared with 2.31±0.12 pW/cell in the control group (p<0.001). The groups with subclinical hyperthyroidism (N = 7) and subclinical hypothyroidism (N=9) had lymphocyte heat production rates of 2.14±0.11 and 2.56±0.15 pW/cell, respectively, not significantly different from that in the controls. Consistently, there was no significant difference between patients with subclinical hyperthyroidism (N=5) and controls (N=5) with regard to lymphocyte energy production as calculated from separately measured oxygen comsumption rates in vitro, 1.36±0.20 and 1.56±0.12 pW/cell, respectively. Thus microcalorimetry seems to be suitable for studying the influence of thyroid hormones on cellular metabolism. Subclinical thyroid dysfunction does not seem to alter the overall rate of lymphocyte metabolism.

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