Three-compartmental analysis of effects of D-propranolol on thyroid hormone kinetics

1988 ◽  
Vol 255 (1) ◽  
pp. E80-E86 ◽  
Author(s):  
J. T. van der Heijden ◽  
E. P. Krenning ◽  
H. van Toor ◽  
G. Hennemann ◽  
R. Docter
Keyword(s):  
Mass Transfer ◽  
Thyroid Hormone ◽  
Mass Transfer Rate ◽  
Kinetic Studies ◽  
Compartmental Analysis ◽  
Metabolic Clearance ◽  
Free T4 ◽  
Transfer Rates ◽  
Plasma Pool ◽  
Low T3

Tracer thyroxine (T4), 3.3',5-triiodothyronine (T3), and 3,3',5'-triiodothyronine (rT3) kinetic studies were performed in normal T4 substituted subjects before and during oral D-propranolol treatment to determine whether changes in thyroid hormone metabolism in a propranolol-induced low-T3 syndrome result from inhibition of 5'-deiodination or inhibition of transport of iodothyronines into tissues. Data were analyzed according to a three-compartmental model of distribution and metabolism. T4 plasma appearance rate decreased by 16% (P less than 0.01), reflecting a decreased intestinal absorption of orally administered T4 during propranolol. Serum T4 and free T4 levels increased significantly by 14%, whereas T4 metabolic clearance rate (MCR) was lowered by 26% (P less than 0.001). No changes were observed in size of the three T4 compartments or in fractional and mass transfer rates of T4 from plasma to the rapidly (REP) and slowly (SEP) equilibrating pools. Serum T3, free T3, T3 plasma pool, T3 mass transfer rate to REP and SEP, and the T3 pool masses were all significantly decreased during propranolol to a similar extent as the T3 plasma production rate (PR). T3 MCR decreased by 14% (P less than 0.05). Serum total and free rT3 increased, whereas the rT3 MCR was substantially lowered during propranolol (P less than 0.001). The rT3 plasma pool, rT3 REP and SEP, and the mass transfer rates to REP and SEP increased, whereas no alterations were observed in rT3 PR and fractional transfer rates of rT3 to REP and SEP.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of caloric deprivation on thyroid hormone tissue uptake and generation of low-T3 syndrome

1986 ◽  
Vol 251 (2) ◽  
pp. E156-E163 ◽  
Author(s):  
J. T. van der Heyden ◽  
R. Docter ◽  
H. van Toor ◽  
J. H. Wilson ◽  
G. Hennemann ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Thyroid Hormone ◽  
Production Rate ◽  
Mass Transfer Rate ◽  
Metabolic Clearance ◽  
Low T3 Syndrome ◽  
Serum Free ◽  
Free T3 ◽  
Plasma Pool ◽  
Low T3

Changes in thyroid hormone metabolism in the low-3,5,3'-triiodothyronine (T3) syndrome cannot be fully explained in all conditions by a decrease in 5'-deiodinase activity. Recent observations showed that in rat hepatocytes iodothyronines are taken up by an active transport mechanism. To investigate whether regulation, i.e., inhibition of active transmembraneous transport for iodothyronines in humans may contribute to the generation of the low-T3 syndrome, tracer thyroxine (T4) and T3 kinetic studies were performed in 10 obese subjects before and after 7 days on a 240 kcal diet. Kinetics analyses were performed according to a three-pool model of distribution and metabolism for both T4 and T3. For T4 kinetics, during caloric deprivation serum total T4 and plasma pool did not change and production rate and metabolic clearance rate (MCR) were significantly lower. Despite a significantly higher serum free T4, the mass transfer rate to the rapidly equilibrating pool (REP) and the slowly equilibrating pool (SEP) diminished significantly, leading to smaller tissue pools. For T3 kinetics, both serum total T3, free T3, plasma pool, and production rate diminished significantly, while MCR remained unchanged. Mass transfer rates to the REP and the SEP were lowered by approximately 50%, leading to smaller tissue pools. These changes cannot be fully explained by a similar decrease of serum free T3 (only 25%), indicating a diminished transport efficiency for T3. In conclusion, during caloric restriction, transport of T4 and T3 into tissues is diminished, and this phenomenon is much more pronounced for T4 than for T3.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Thyroid hormone profile and PELOD score in children with sepsis

2014 ◽  
Vol 54 (4) ◽  
pp. 245
Author(s):  
Agung G. Tanurahardja ◽  
Antonius H. Pudjiadi ◽  
Pramita G. Dwipoerwantoro ◽  
Aman Pulungan
Keyword(s):  
Thyroid Hormone ◽  
Pediatric Intensive Care ◽  
Cross Sectional Study ◽  
Free T4 ◽  
Cross Sectional ◽  
Risk Of Death ◽  
Hormone Profile ◽  
Low T3 ◽  
Hormonal Dysfunction ◽  
Pelod Score

Background Thyroid hormonal dysfunction, also known aseuthyroid sick syndrome or nonthyroidal illness, can be seenin sepsis. There have been few studies on thyroid hormonedysfunction in septic children, as well as on a relationshipbetween their thyroid hormone profiles and pediatric logisticorgan dysfunction (PELOD) scores. Procakitonin (PCT) is oneof the sepsis biomarker.Objective To evaluate the thyroid hormone profile in childrenwith sepsis as well as to assess for a correlation between the thyroidlevels and PELOD scores, PCT levels, and patient outcomes.Methods This cross-sectional study included children aged 1- 18years admitted to the pediatric intensive care unit (PICU) with aprimary diagnosis of sepsis. PELOD scores and thyroid hormonallevels were assessed once during the first 24 hours after PICUadmission.Results Thirty subjects were included in the study. The medianvalues ofT3, free T4, and TSH were 45 (range 17 -133) ng/dL,0.81 (range 0.3-1.57) ng/dL, and 1.36 (range 0.05-7.78) μIU/L,respectively. The T3, free T4, and TSH levels were decreased in97%, 50% and 40% of the subjects. There were no significantdifferences between low and normal to high TSH with regards tothe PELOD score (P=0.218), PCT level (P=0.694), or patientoutcomes (P=0.55). The risk of death increased by 15 timesamong the subjects with PELOD score ~20 compared to thosewith PELOD score <20 (OR 15; 95%CI: 1.535 to 146.545;P=0.012).Conclusion Thyroid hormones are decreased in septic childrenwith the majority having low T3. A high PELOD score is stronglycorrelated with mortality and can be used as a prognostic parameterfor septic children in the PICU, but there is no correlation withdecreased TSH.

Influence of Non-Newtonian Rheology on Mass Transfer From a Biofluid in Separated and Reattached Flows

2018 ◽  
Author(s):  
Khaled J. Hammad
Keyword(s):  
Mass Transfer ◽  
Yield Stress ◽  
Mass Transfer Rate ◽  
Flow Region ◽  
Shear Thinning ◽  
Recirculation Region ◽  
Transfer Rates ◽  
Separated And Reattached Flow ◽  
The Impact ◽  
Wall Mass

Influence of the rheological model selection on the flow and mass transfer behavior of human blood in a separated and reattached flow region is investigated. Newtonian and non-Newtonian hemorheological models that account for the yield stress and shear-thinning characteristics of blood are used. The conservation of mass, momentum, and species equations as well as the Herschel-Bulkley constitutive equation are solved numerically using a finite-difference scheme. A parametric study is performed to reveal the impact of flow restriction and rheological modelling on blood-borne oxygen exchange with the confining walls. The wall mass transfer rates within the separated and reattached regions display a strong dependency on the used hemorheological model. Newtonian and non-Newtonian models result in a peak wall mass transfer rate within the recirculation region. However, non-Newtonian models that account for the yield stress and shear-thinning effects predict a substantial, highly localized, drop in the wall mass transfer rates of oxygen, at the reattachment point.

scholarly journals Minimum Orbital Period of Cataclysmic Variables

1979 ◽  
Vol 53 ◽  
pp. 504-504
Author(s):  
B. Paczynski ◽  
W. Krzeminski
Keyword(s):  
Mass Transfer ◽  
Angular Momentum ◽  
Orbital Period ◽  
Time Scale ◽  
Transfer Rate ◽  
Main Sequence ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Transfer Rates ◽  
Angular Momentum Loss

The shortest known orbital period of a cataclysmic binary with a hydrogen dwarf secondary filling its Roche lobe is about 80 minutes. Theoretically the shortest possible orbital period for such a system is less than 60 minutes. We tried to explain why the periods shorter than 80 minutes are not observed. We estimated the time scale of angular momentum loss of a cataclysmic binary and the resulting mass transfer rate. The minimum orbital period for a given Ṁ is obtained during the transition of the secondary from the Main Sequence onto the Degenerate Dwarf Sequence. Pmin ∝ Ṁ½ Therefore, only those systems can reach low P for which Ṁ is small. This explains why among the shortest period cataclysmic variables there are no novae: presumably their mass transfer rates are too large. It also indicates that “polars” (AM Her-type stars) and SU UMa-type stars should have low Ṁ.

scholarly journals SWSex Stars, Old Novae, and the Evolution of Cataclysmic Variables

2015 ◽  
Vol 2 (1) ◽  
pp. 188-191 ◽  
Author(s):  
L. Schmidtobreick ◽  
C. Tappert
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
High Mass ◽  
Period Range ◽  
Transfer Rates ◽  
Low Mass ◽  
Orbital Periods ◽  
Nova Outburst

The population of cataclysmic variables with orbital periods right above the period gap are dominated by systems with extremely high mass transfer rates, the so-called SW Sextantis stars. On the other hand, some old novae in this period range which are expected to show high mass transfer rate instead show photometric and/or spectroscopic resemblance to low mass transfer systems like dwarf novae. We discuss them as candidates for so-called hibernating systems, CVs that changed their mass transfer behaviour due to a previously experienced nova outburst. This paper is designed to provide input for further research and discussion as the results as such are still very preliminary.

Large-scale energetic coherent structures and their effects on wall mass transfer rate behind orifice in round pipe

2021 ◽  
Vol 927 ◽  
Author(s):  
F. Shan ◽  
S.Y. Qin ◽  
Y. Xiao ◽  
A. Watanabe ◽  
M. Kano ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Coherent Structures ◽  
Transfer Rate ◽  
Large Scale ◽  
Mass Transfer Rate ◽  
Low Frequency ◽  
Stochastic Estimation ◽  
Transfer Rates ◽  
Wall Mass

This paper first uses a low-speed stereoscopic particle image velocimetry (SPIV) system to measure the convergent statistical quantities of the flow field and then simultaneously measure the time-resolved flow field and the wall mass transfer rate by a high-speed SPIV system and an electrochemical system, respectively. We measure the flow field and wall mass transfer rate under upstream pipe Reynolds numbers between 25 000 and 55 000 at three specific locations behind the orifice plate. Moreover, we apply proper orthogonal decomposition (POD), stochastic estimation and spectral analysis to study the properties of the flow field and the wall mass transfer rate. More importantly, we investigate the large-scale coherent structures’ effects on the wall mass transfer rate. The collapse of the wall mass transfer rates’ spectra by the corresponding time scales at the three specific positions of orifice flow suggest that the physics of low-frequency wall mass transfer rates are probably the same, although the flow fields away from the wall are quite different. Furthermore, the spectra of the velocity reconstructed by the most energetic eigenmodes agree well with the wall mass transfer rate in the low-frequency region, suggesting that the first several energetic eigenmodes capture the flow dynamics relevant to the low-frequency variation of the wall mass transfer. Stochastic estimation results of the velocity field associated with large wall mass transfer rate at all three specific locations further reveal that the most energetic coherent structures are correlated with the wall mass transfer rate.

scholarly journals 1RXS J232953.9+062814: A Possible Progenitor of AM CVn Stars

2004 ◽  
Vol 194 ◽  
pp. 109-110
Author(s):  
M. Uemura
Keyword(s):  
Mass Transfer ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
High Mass ◽  
Recurrence Time ◽  
Apparent Magnitude ◽  
Evolutionary Status ◽  
Transfer Rates ◽  
Secondary Star ◽  
Orbital Periods

AbstractWe revealed that the hydrogen-rich cataclysmic variable lRXS J232953.9+062814 is an SU UMa-type dwarf nova with a superbump period of 66.774±0.010 min. A photometric orbital period is determined to be 64.184± 0.003 min, which is below the period minimum. Although the standard evolutionary scenario of cataclysmic variables predicts lower mass-transfer rates in systems with shorter orbital periods, its short recurrence time of outbursts and bright apparent magnitude indicate that this object has a relatively high mass-transfer rate. With the analogous system V485 Cen, these objects establish the first subpopulation in hydrogen-rich cataclysmic variables below the period minimum. Concerning the evolutionary status of them, we propose that they are progenitors of AM CVn stars on evolutionary courses in which systems have an evolved secondary star with a hydrogen-exhausted core.

scholarly journals Thyroid Hormone Concentrations, Disease, Physical Function, and Mortality in Elderly Men

2005 ◽  
Vol 90 (12) ◽  
pp. 6403-6409 ◽  
Author(s):  
Annewieke W. van den Beld ◽  
Theo J. Visser ◽  
Richard A. Feelders ◽  
Diederick E. Grobbee ◽  
Steven W. J. Lamberts
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Hormones ◽  
Physical Function ◽  
Grip Strength ◽  
High Serum ◽  
Healthy Adults ◽  
Elderly Men ◽  
Normal Range ◽  
Free T4 ◽  
Low T3

Context: Physiological changes in thyroid hormone concentrations might be related to changes in the overall physical function in the elderly. Objective: We determined to what extent thyroid hormone concentrations are related to physical function and mortality in elderly men. Design: A longitudinal population study (the Zoetermeer study) was conducted. Mortality was registered in the subsequent 4 yr. Participants: Four hundred three independently and ambulatory living men (aged 73–94 yr) participated. Main Outcome Measures: The study examined the association between serum thyroid hormones and parameters of physical function as well as the association with mortality. Methods: TSH, free T4 (FT4) total T4, T3, rT3, and T4-binding globulin were measured. Physical function was estimated by the number of problems in activities of daily living, a measure of physical performance score (PPS), leg extensor strength and grip strength, bone density, and body composition. Results: Serum rT3 increased significantly with age and the presence of disease. Sixty-three men met the biochemical criteria for the low T3 syndrome (decreased serum T3 and increased serum rT3). This was associated with a lower PPS, independent of disease. Furthermore, higher serum FT4 (within the normal range of healthy adults) and rT3 (above the normal range of healthy adults) were related with a lower grip strength and PPS, independent of age and disease. Isolated low T3 was associated with a better PPS and a higher lean body mass. Low FT4 was related to a decreased risk of 4-yr mortality. Conclusions: In a population of independently living elderly men, higher FT4 and rT3 concentrations are associated with a lower physical function. High serum rT3 may result from a decreased peripheral metabolism of thyroid hormones due to the aging process itself and/or disease and may reflect a catabolic state. Low serum FT4 is associated with a better 4-yr survival; this may reflect an adaptive mechanism to prevent excessive catabolism.

Mass Transfer in Single Bends Under Annular Two Phase Flow Conditions

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
H. Mazhar ◽  
D. Ewing ◽  
J. S. Cotton ◽  
C. Y. Ching
Keyword(s):  
Mass Transfer ◽  
Mass Transfer Rate ◽  
Local Maximum ◽  
Outer Wall ◽  
Water Velocity ◽  
Maximum Mass ◽  
Flow Conditions ◽  
Air Velocity ◽  
Two Phase ◽  
Transfer Rates

The distributions of the mass transfer coefficient in horizontal 90 deg bends were measured under a range of two phase annular flow conditions. A dissolving wall technique at a high Schmidt number (Sc = 1280) is used for the measurements. The maximum mass transfer occurred on the centerline of the bend outer wall at an angle of approximately 50 deg from the bend inlet under all tested conditions. The area of maximum mass transfer rate was found to span approximately 30 deg in the circumferential direction. A second region of enhanced mass transfer occurred on the latter part of the bend with a local maximum occurring slightly off the bend centerline in some cases. Changing the air and water superficial velocities (Jv = 22–30 m/s, JL = 0.17–0.41 m/s) showed that the air velocity had a larger effect on the mass transfer rates than the water velocity; however, the effect of the water velocity on the mass transfer was not insignificant.

scholarly journals On the three-phase mass transfer with solid particles adhered to the gas-liquid interface

2003 ◽  
Vol 1 (2) ◽  
pp. 160-177
Author(s):  
Endre Nagy
Keyword(s):  
Mass Transfer ◽  
Particle Size ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Mass Transfer Rate ◽  
Liquid Interface ◽  
Solid Particles ◽  
Transfer Model ◽  
Transfer Rates ◽  
Layer Packing

AbstractA heterogeneous, multi-layer mass transfer model is proposed for prediction of the effect of multi-layer packing of catalyst particles adhered to the gas-liquid interface. The behavior of the mass transfer rate with respect to the multi-layer packing, to the particle size and mass transfer coefficient without particles is discussed. It is shown that enhancement can be considerably increased by multi-layer packing compared to that of mono-layer packing, depending on the values of particle size and mass transfer coefficient. The predicted mass transfer rates using the proposed model was verified with experimental data taken from the literature. The model presented should be superior to that of published in the literature.

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