ADJUSTMENTS TO CONSTANT LOW TEMPERATURES IN WHITE RATS LIVING IN GROUPS

1963 ◽  
Vol 41 (3) ◽  
pp. 587-595 ◽  
Author(s):  
O. Héroux
Keyword(s):  
Low Temperatures ◽  
Metabolic Adaptation ◽  
Experimental Conditions ◽  
Cold Stimulus ◽  
White Rats ◽  
Essential Components ◽  
Resting Metabolism ◽  
Increased Sensitivity ◽  
Shivering Thermogenesis ◽  
Fundamental Mechanism

White rats, in groups of 10, were exposed for 3 months in the laboratory to constant temperatures of 19 °C or −10 °C. Grouping the animals did not alter the pattern of metabolic adaptation usually observed in individually cold-acclimated rats and recently observed in group-caged white rats exposed outdoors during the winter. This pattern of adaptation is characterized by an increased capacity for heat production, as shown by a longer survival time at −35 °C, a reduction of shivering, an increased sensitivity to noradrenaline, an increased ear vascularization, a reduction in protein and fat deposition, and an enlargement of heart, liver, and kidneys. Group-caging at constant low temperature (a) prevented the development of cold injuries and the enlargement of pituitary, thyroid, adrenals, which are usually observed in individually cold-exposed rats indoors, (b) resulted in an increased resting metabolism, normal adrenal cortex activity, and no increase in pelt insulation in contrast to that previously found in white rats grouped outdoors during the winter. These different adjustments to cold in white rats exposed to different sets of environmental conditions are compared with similar adjustments found in wild Norway rats.From these comparisons, one must conclude that many of the structural and endocrine adjustments observed in individually cold-acclimated rats in the laboratory are reactions peculiar to continuous cold stimulus, i.e. reactions to a specific set of experimental conditions rather than essential components of the fundamental mechanism for non-shivering thermogenesis.

ADJUSTMENTS TO CONSTANT LOW TEMPERATURES IN WHITE RATS LIVING IN GROUPS

1963 ◽  
Vol 41 (1) ◽  
pp. 587-595
Author(s):  
O. Héroux
Keyword(s):  
Low Temperatures ◽  
Metabolic Adaptation ◽  
Experimental Conditions ◽  
Cold Stimulus ◽  
White Rats ◽  
Essential Components ◽  
Resting Metabolism ◽  
Increased Sensitivity ◽  
Shivering Thermogenesis ◽  
Fundamental Mechanism

White rats, in groups of 10, were exposed for 3 months in the laboratory to constant temperatures of 19 °C or −10 °C. Grouping the animals did not alter the pattern of metabolic adaptation usually observed in individually cold-acclimated rats and recently observed in group-caged white rats exposed outdoors during the winter. This pattern of adaptation is characterized by an increased capacity for heat production, as shown by a longer survival time at −35 °C, a reduction of shivering, an increased sensitivity to noradrenaline, an increased ear vascularization, a reduction in protein and fat deposition, and an enlargement of heart, liver, and kidneys. Group-caging at constant low temperature (a) prevented the development of cold injuries and the enlargement of pituitary, thyroid, adrenals, which are usually observed in individually cold-exposed rats indoors, (b) resulted in an increased resting metabolism, normal adrenal cortex activity, and no increase in pelt insulation in contrast to that previously found in white rats grouped outdoors during the winter. These different adjustments to cold in white rats exposed to different sets of environmental conditions are compared with similar adjustments found in wild Norway rats.From these comparisons, one must conclude that many of the structural and endocrine adjustments observed in individually cold-acclimated rats in the laboratory are reactions peculiar to continuous cold stimulus, i.e. reactions to a specific set of experimental conditions rather than essential components of the fundamental mechanism for non-shivering thermogenesis.

scholarly journals Software-guided microscale flow calorimeter for efficient acquisition of thermokinetic data

2021 ◽  
Author(s):  
Timothy Aljoscha Frede ◽  
Marlene Dietz ◽  
Norbert Kockmann
Keyword(s):  
Design Of Experiments ◽  
Process Development ◽  
Reaction Conditions ◽  
Experimental Conditions ◽  
Flow Calorimeter ◽  
Microscale Flow ◽  
Increased Sensitivity ◽  
Important Time ◽  
Optimal Reaction

AbstractFast chemical process development is inevitably linked to an optimized determination of thermokinetic data of chemical reactions. A miniaturized flow calorimeter enables increased sensitivity when examining small amounts of reactants in a short time compared to traditional batch equipment. Therefore, a methodology to determine optimal reaction conditions for calorimetric measurement experiments was developed and is presented in this contribution. Within the methodology, short-cut calculations are supplemented by computational fluid dynamics (CFD) simulations for a better representation of the hydrodynamics within the microreactor. This approach leads to the effective design of experiments. Unfavourable experimental conditions for kinetics experiments are determined in advance and therefore, need not to be considered during design of experiments. The methodology is tested for an instantaneous acid-base reaction. Good agreement of simulations was obtained with experimental data. Thus, the prediction of the hydrodynamics is enabled and the first steps towards a digital twin of the calorimeter are performed. The flow rates proposed by the methodology are tested for the determination of reaction enthalpy and showed that reasonable experimental settings resulted. Graphical abstract A methodology is suggested to evaluate optimal reaction conditions for efficientacquisition of kinetic data. The experimental design space is limited by thestepwise determination of important time scales based on specified input data.

scholarly journals Investigation of Base-free Copper-Catalysed Azide–Alkyne Click Cycloadditions (CuAAc) in Natural Deep Eutectic Solvents as Green and Catalytic Reaction Media

2021 ◽  
Author(s):  
Salvatore V. Giofrè ◽  
Matteo Tiecco ◽  
Angelo Ferlazzo ◽  
Roberto Romeo ◽  
Gianluca Ciancaleoni ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Materials Science ◽  
Cycloaddition Reaction ◽  
Deep Eutectic Solvents ◽  
Green Solvents ◽  
Experimental Conditions ◽  
Active Reaction ◽  
Natural Deep Eutectic Solvents ◽  
Catalytic Intermediates ◽  
Reaction Media

<p>The click cycloaddition reaction of azides and alkynes affording 1,2,3-triazoles is a widely used and effective chemical transformation, applied to obtain relevant products in medicine, biology and materials science. In this work, a set of Natural Deep Eutectic Solvents (NADESs) as green and “active” reaction media, has been investigated in the copper-catalysed azide–alkyne cycloaddition reactions (CuAAc). The use of these innovative solvents has shown to improve the reaction effectiveness, giving excellent yields. NADESs proved to be “active” in these transformations for the absence of added bases in all the performed reactions and in several cases, for their reducing capabilities. The reactions outcomes were rationalized by DFT calculations which demonstrated the involvement of H-bonds between DESs and alkynes as well as a stabilization of copper catalytic intermediates. The green experimental conditions, namely the absence of a base, the low temperatures, the lowering of reagents and the possibility of recycling of the green solvents, outline the great potential of NADESs for CuAAc and in general, for green organic synthesis. </p>

SEASONAL ADJUSTMENTS IN CAPTURED WILD NORWAY RATS: II. SURVIVAL TIME, PELT INSULATION, SHIVERING, AND METABOLIC AND PRESSOR RESPONSES TO NORADRENALINE

1962 ◽  
Vol 40 (1) ◽  
pp. 537-545 ◽  
Author(s):  
O. Héroux ◽  
Donna Wright
Keyword(s):  
Survival Time ◽  
Metabolic Response ◽  
Cold Temperature ◽  
White Rats ◽  
Winter Conditions ◽  
Pressor Responses ◽  
Wild Rats ◽  
Norway Rats ◽  
Shivering Thermogenesis

During the winter, wild rats (Rattus norwegicus) develop metabolic adjustments similar to those found in the white rats acclimated to cold in the laboratory. The rate of shivering found in the winter-captured wild rats is lower than that found in the summer-captured rats, indicating the presence of non-shivering thermogenesis. The metabolic response to noradrenaline is enhanced suggesting that non-shivering metabolism in these wild rats, as in the case of white rats, is mediated by noradrenaline. Unlike white rats acclimated to a constant cold temperature in the laboratory, but like white rats acclimatized to cold by group exposure to outdoor winter conditions, wild rats develop a greater pelt insulation in winter.

Metabolism and force in hypertrophic smooth muscle from rat urinary bladder

1990 ◽  
Vol 258 (5) ◽  
pp. C923-C932 ◽  
Author(s):  
A. Arner ◽  
U. Malmqvist ◽  
B. Uvelius
Keyword(s):  
Outlet Obstruction ◽  
Electrical Field Stimulation ◽  
Metabolic Adaptation ◽  
Active Force ◽  
Force Output ◽  
Experimental Conditions ◽  
Muscle Area ◽  
Rat Urinary Bladder ◽  
High K ◽  
Tension Cost

Ten days of urinary outlet obstruction in the rat induced a threefold increase in bladder weight. Active force of control and hypertrophic bladder muscle strips was measured at varying PO2 levels after high-K+, carbachol, or electrical field stimulation. Highest force output was obtained with carbachol. Force per muscle area was lower in the hypertrophic muscles. The basal rates of oxygen consumption and lactate formation were similar in the two groups. The metabolic tension cost (ATP turnover/active force) was similar in the two groups for activation with high K+ and carbachol. In anoxia the active force decreased, but this was less pronounced in the hypertrophied muscle. Hypertrophied muscle could, in contrast to the controls, maintain a sustained K+ contracture in anoxia. Basal metabolic rates and tension cost were markedly reduced in anoxia for both groups. The lower force per area with unaltered tension cost, in hypertrophic muscles under all experimental conditions, may reflect unaltered intrinsic properties of the contractile system, although the amount of contractile material has decreased relative to cell volume. The increased resistance to anoxia may reflect a metabolic adaptation to impaired oxygen supply to the hypertrophied tissue.

scholarly journals Investigation of Base-free Copper-Catalysed Azide–Alkyne Click Cycloadditions (CuAAc) in Natural Deep Eutectic Solvents as Green and Catalytic Reaction Media

2021 ◽  
Author(s):  
Salvatore V. Giofrè ◽  
Matteo Tiecco ◽  
Angelo Ferlazzo ◽  
Roberto Romeo ◽  
Gianluca Ciancaleoni ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Materials Science ◽  
Cycloaddition Reaction ◽  
Deep Eutectic Solvents ◽  
Green Solvents ◽  
Experimental Conditions ◽  
Active Reaction ◽  
Natural Deep Eutectic Solvents ◽  
Catalytic Intermediates ◽  
Reaction Media

<p>The click cycloaddition reaction of azides and alkynes affording 1,2,3-triazoles is a widely used and effective chemical transformation, applied to obtain relevant products in medicine, biology and materials science. In this work, a set of Natural Deep Eutectic Solvents (NADESs) as green and “active” reaction media, has been investigated in the copper-catalysed azide–alkyne cycloaddition reactions (CuAAc). The use of these innovative solvents has shown to improve the reaction effectiveness, giving excellent yields. NADESs proved to be “active” in these transformations for the absence of added bases in all the performed reactions and in several cases, for their reducing capabilities. The reactions outcomes were rationalized by DFT calculations which demonstrated the involvement of H-bonds between DESs and alkynes as well as a stabilization of copper catalytic intermediates. The green experimental conditions, namely the absence of a base, the low temperatures, the lowering of reagents and the possibility of recycling of the green solvents, outline the great potential of NADESs for CuAAc and in general, for green organic synthesis. </p>

scholarly journals Investigation of Base-free Copper-Catalysed Azide–Alkyne Click Cycloadditions (CuAAc) in Natural Deep Eutectic Solvents as Green and Catalytic Reaction Media

2021 ◽  
Author(s):  
Salvatore V. Giofrè ◽  
Matteo Tiecco ◽  
Angelo Ferlazzo ◽  
Roberto Romeo ◽  
Gianluca Ciancaleoni ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Materials Science ◽  
Cycloaddition Reaction ◽  
Deep Eutectic Solvents ◽  
Green Solvents ◽  
Experimental Conditions ◽  
Active Reaction ◽  
Natural Deep Eutectic Solvents ◽  
Catalytic Intermediates ◽  
Reaction Media

<p>The click cycloaddition reaction of azides and alkynes affording 1,2,3-triazoles is a widely used and effective chemical transformation, applied to obtain relevant products in medicine, biology and materials science. In this work, a set of Natural Deep Eutectic Solvents (NADESs) as green and “active” reaction media, has been investigated in the copper-catalysed azide–alkyne cycloaddition reactions (CuAAc). The use of these innovative solvents has shown to improve the reaction effectiveness, giving excellent yields. NADESs proved to be “active” in these transformations for the absence of added bases in all the performed reactions and in several cases, for their reducing capabilities. The reactions outcomes were rationalized by DFT calculations which demonstrated the involvement of H-bonds between DESs and alkynes as well as a stabilization of copper catalytic intermediates. The green experimental conditions, namely the absence of a base, the low temperatures, the lowering of reagents and the possibility of recycling of the green solvents, outline the great potential of NADESs for CuAAc and in general, for green organic synthesis. </p>

EFFECTS OF SECTION OF THE CORPUS CALLOSUM ON DECOMPRESSION HYPOXIA AND ON PENTYLENETETRAZOL (METRAZOL) CONVULSIONS

1962 ◽  
Vol 40 (11) ◽  
pp. 1477-1491 ◽  
Author(s):  
S. J. Manax ◽  
G. W. Stavraky
Keyword(s):  
Corpus Callosum ◽  
Experimental Conditions ◽  
S Waves ◽  
Implanted Electrodes ◽  
White Rats ◽  
Wave Patterns ◽  
Metrazol Convulsions ◽  
Eeg Changes ◽  
The Brain ◽  
Eeg Pattern

Electroencephalographic studies were carried out in white rats with chronically implanted electrodes located on the skull over the frontal areas of the brain, with the animals suspended in a sling in a decompression chamber. Exposed to simulated elevated altitude at weekly intervals 4 to 6 months after section of the corpus callosum 26 animals revealed a greater sensitivity to hypoxia than 22 controls. This was shown by a lower threshold of convulsibility and by a longer duration of the convulsions. Under the experimental conditions employed the electrocortical activity in control animals consisted of 1.5–3 c/s and 4–6 c/s waves of up to 40-μv amplitude with 11–14 c/s waves superimposed. In the corpus-callotomized rats the activity was somewhat slower and of a higher amplitude, this being more apparent [Formula: see text] months after the operation than at the time of the decompression experiments. Decompression of both groups of animals resulted in characteristic EEG changes culminating in the appearance of hypoxic preconvulsive potentials of high voltage (60–180 μv) and slow frequency (1.5–3 c/s) which were first grouped in paroxysms of about 3 to 5 seconds' duration, later becoming continuous. When decompression was continued, this activity was followed by convulsive discharges, all of the manifestations being more pronounced and recurring at lower altitudes in the corpus-callotomized animals than in the controls. An analysis of the wave patterns in 28 sacrifice experiments with transection of the spinal cord and curarization of the animals showed that the observed EEG activity did not depend on motor components.The EEG patterns during the excitatory stages of hypoxia or asphyxia resembled closely certain phases of pentylenetetrazol-induced activity; however, at the height of the convulsive EEG pattern induced by pentylenetetrazol, periods of asphyxia disorganized the spike activity caused by this agent and markedly depressed the EEG.

EFFECTS OF SECTION OF THE CORPUS CALLOSUM ON DECOMPRESSION HYPOXIA AND ON PENTYLENETETRAZOL (METRAZOL) CONVULSIONS

1962 ◽  
Vol 40 (1) ◽  
pp. 1477-1491
Author(s):  
S. J. Manax ◽  
G. W. Stavraky
Keyword(s):  
Corpus Callosum ◽  
Experimental Conditions ◽  
S Waves ◽  
Implanted Electrodes ◽  
White Rats ◽  
Wave Patterns ◽  
Metrazol Convulsions ◽  
Eeg Changes ◽  
The Brain ◽  
Eeg Pattern

Electroencephalographic studies were carried out in white rats with chronically implanted electrodes located on the skull over the frontal areas of the brain, with the animals suspended in a sling in a decompression chamber. Exposed to simulated elevated altitude at weekly intervals 4 to 6 months after section of the corpus callosum 26 animals revealed a greater sensitivity to hypoxia than 22 controls. This was shown by a lower threshold of convulsibility and by a longer duration of the convulsions. Under the experimental conditions employed the electrocortical activity in control animals consisted of 1.5–3 c/s and 4–6 c/s waves of up to 40-μv amplitude with 11–14 c/s waves superimposed. In the corpus-callotomized rats the activity was somewhat slower and of a higher amplitude, this being more apparent [Formula: see text] months after the operation than at the time of the decompression experiments. Decompression of both groups of animals resulted in characteristic EEG changes culminating in the appearance of hypoxic preconvulsive potentials of high voltage (60–180 μv) and slow frequency (1.5–3 c/s) which were first grouped in paroxysms of about 3 to 5 seconds' duration, later becoming continuous. When decompression was continued, this activity was followed by convulsive discharges, all of the manifestations being more pronounced and recurring at lower altitudes in the corpus-callotomized animals than in the controls. An analysis of the wave patterns in 28 sacrifice experiments with transection of the spinal cord and curarization of the animals showed that the observed EEG activity did not depend on motor components.The EEG patterns during the excitatory stages of hypoxia or asphyxia resembled closely certain phases of pentylenetetrazol-induced activity; however, at the height of the convulsive EEG pattern induced by pentylenetetrazol, periods of asphyxia disorganized the spike activity caused by this agent and markedly depressed the EEG.

Comparative Survival of E. Coli, F+Bacteriophages, HAV and Poliovirus 1 in Wastewater and Groundwater

1993 ◽  
Vol 27 (3-4) ◽  
pp. 401-407 ◽  
Author(s):  
A. M. Nasser ◽  
Y. Tchorch ◽  
B. Fattal
Keyword(s):  
Bacterial Growth ◽  
Low Temperatures ◽  
Water Sources ◽  
Water Type ◽  
Experimental Conditions ◽  
E Coli ◽  
Pathogenic Viruses ◽  
Raw Wastewater

This study was designed to compare the die-off of E.coli and F*bacteriophages with that of enteric pathogenic viruses in groundwater and raw wastewater at various temperatures. At low temperatures, the die-off of E.coli was greater than that of HAV and poliovirus 1. Under conditions compatible with bacterial growth no die-off of E.coli was observed. Under most experimental conditions no die-off was observed for F*bacteriophages. The survival of HAV and poliovirus 1 was strongly affected by temperature. Regardless of the water type, the highest die-off of viruses was observed at 30°C, whereas at 10°C the titer of HAV and poliovirus 1 was reduced by 1 to 2 log10 after 90 days incubation. The data presented in this study indicated that E.coli cannot serve as an index for the survival of HAV and poliovirus 1 in ground and wastewater. Since F+bacteriophages were not affected by the tested conditions, their acceptance as indicators for viral pollution of water sources needs further evaluation.

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