Temperature-dependence of haematoporphyrin derivative uptake in vitro

1988 ◽  
Vol 3 (1-4) ◽  
pp. 179-184 ◽  
Author(s):  
Norio Miyoshi ◽  
Nobuo Matsumoto ◽  
Haruo Hisazumi ◽  
Masaru Fukuda
Keyword(s):  
Temperature Dependence ◽  
Haematoporphyrin Derivative

Temperature-dependence of the DnaA–DNA interaction and its effect on the autoregulation of dnaA expression

2012 ◽  
Vol 449 (2) ◽  
pp. 333-341 ◽  
Author(s):  
Chiara Saggioro ◽  
Anne Olliver ◽  
Bianca Sclavi
Keyword(s):  
Temperature Dependence ◽  
Binding Sites ◽  
Dna Interaction ◽  
Bacterial Dna ◽  
Dnaa Protein ◽  
High Affinity ◽  
Key Factor

The DnaA protein is a key factor for the regulation of the timing and synchrony of initiation of bacterial DNA replication. The transcription of the dnaA gene in Escherichia coli is regulated by two promoters, dnaAP1 and dnaAP2. The region between these two promoters contains several DnaA-binding sites that have been shown to play an important role in the negative auto-regulation of dnaA expression. The results obtained in the present study using an in vitro and in vivo quantitative analysis of the effect of mutations to the high-affinity DnaA sites reveal an additional effect of positive autoregulation. We investigated the role of transcription autoregulation in the change of dnaA expression as a function of temperature. While negative auto-regulation is lost at dnaAP1, the effects of both positive and negative autoregulation are maintained at the dnaAP2 promoter upon lowering the growth temperature. These observations can be explained by the results obtained in vitro showing a difference in the temperature-dependence of DnaA–ATP binding to its high- and low-affinity sites, resulting in a decrease in DnaA–ATP oligomerization at lower temperatures. The results of the present study underline the importance of the role for autoregulation of gene expression in the cellular adaptation to different growth temperatures.

Temperature dependence of proton relaxation times in vitro

1987 ◽  
Vol 5 (3) ◽  
pp. 189-199 ◽  
Author(s):  
T.R. Nelson ◽  
S.M. Tung
Keyword(s):  
Temperature Dependence ◽  
Relaxation Times ◽  
Proton Relaxation

Association of AP1 adaptor complexes with GLUT4 vesicles

1999 ◽  
Vol 112 (24) ◽  
pp. 4793-4800 ◽  
Author(s):  
A.K. Gillingham ◽  
F. Koumanov ◽  
P.R. Pryor ◽  
B.J. Reaves ◽  
G.D. Holman
Keyword(s):  
Temperature Dependence ◽  
Western Blotting ◽  
Brefeldin A ◽  
Intracellular Sorting ◽  
In Vitro Effects ◽  
Gamma S ◽  
Isolated Cell

Nycodenz gradients have been used to examine the in vitro effects of GTP-(gamma)-S on adaptor complex association with GLUT4 vesicles. On addition of GTP-(gamma)-S, GLUT4 fractionates as a heavier population of vesicles, which we suggest is due to a budding or coating reaction. Under these conditions there is an increase in co-sedimentation of GLUT4 with AP1, but not with AP3. Western blotting of proteins associated with isolated GLUT4 vesicles shows the presence of high levels of AP1 and some AP3 but very little AP2 adaptor complexes. Cell free, in vitro association of the AP1 complex with GLUT4 vesicles is increased approximately 4-fold by the addition of GTP-(gamma)-S and an ATP regenerating system. Following GTP-(gamma)-S treatment in vitro, ARF is also recruited to GLUT4 vesicles, and the temperature dependence of ARF recruitment closely parallels that of AP1. The recruitment of both AP1 and ARF are partially blocked by brefeldin A. These data demonstrate that the coating of GLUT4 vesicles can be studied in isolated cell-free fractions. Furthermore, at least two distinct adaptor complexes can associate with the GLUT4 vesicles and it is likely that these adaptors are involved in mediating distinct intracellular sorting events at the level of TGN and endosomes.

Free energy and enthalpy of ATP hydrolysis in the sarcoplasm

1969 ◽  
Vol 174 (1036) ◽  
pp. 348-353 ◽  
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Temperature Dependence ◽  
Thermodynamic Data ◽  
Approximate Calculation ◽  
Atp Hydrolysis ◽  
Equilibrium Conditions ◽  
Thermodynamic Measurements

A rigorous calculation of the free energy available in vivo from ATP hydrolysis requires the following information which is not all available, namely: (i) intra­cellular pH, (ii) activities of all the species of reactants and products in sarcoplasm, (iii) thermodynamic data for all the reactions involved, including values for ionic strength and temperature dependence, and (iv) the extent of deviation from equilibrium conditions, i. e. during contraction. We shall discuss each of these factors in turn and state the assumptions made that allow the approximate calculation of the free energy made available by the following net reaction in the sarcoplasm: ATP +H 2 O → ADP + Pi + H + . (1) Although it can only be an approximation this calculation is useful since it will take into account recent thermodynamic measurements in vitro .

Temperature Dependence of Ultrasonic Propagation Speed and Attenuation in Canine Tissue

2002 ◽  
Vol 24 (4) ◽  
pp. 246-260 ◽  
Author(s):  
U. Techavipoo ◽  
T. Varghese ◽  
J.A. Zagzebski ◽  
T. Stiles ◽  
G. Frank
Keyword(s):  
Temperature Dependence ◽  
Attenuation Coefficient ◽  
Propagation Speed ◽  
Ablative Therapies ◽  
Temperature Ranges ◽  
Higher Temperature ◽  
Ultrasonic Propagation ◽  
Reported Data ◽  
Increasing Temperature

Previously reported data on the temperature dependence of propagation speed in tissues generally span only temperature ranges up to 60°C. However, with the emerging use of thermal ablative therapies, information on variation in this parameter over higher temperature ranges is needed. Measurements of the ultrasonic propagation speed and attenuation in tissue in vitro at discrete temperatures ranging from 25 to 95°C was performed for canine liver, muscle, kidney and prostate using 3 and 5 MHz center frequencies. The objective was to produce information for calibrating temperature-monitoring algorithms during ablative therapy. Resulting curves of the propagation speed vs. temperature for these tissues can be divided into three regions. In the 25–40°C range, the speed of sound increases rapidly with temperature. It increases moderately with temperature in the 40–70°C range, and it then decreases with increasing temperature from 70–95°C. Attenuation coefficient behavior with temperature is different for the various tissues. For liver, the attenuation coefficient is nearly constant with temperature. For kidney, attenuation increases approximately linearly with temperature, while for muscle and prostate tissue, curves of attenuation vs. temperature are flat in the 25–50°C range, slowly rise at medium temperatures (50–70°C), and level off at higher temperatures (70–90°C). Measurements were also conducted on a distilled degassed water sample and the results closely follow values from the literature.

scholarly journals SOD-Mimic Cu(II) Dimeric Complexes Involving Kinetin and Its Derivative: Preparation and Characterization

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Radka Novotná ◽  
Zdeněk Trávníček ◽  
Radovan Herchel
Keyword(s):  
Mass Spectrometry ◽  
Magnetic Susceptibility ◽  
Temperature Dependence ◽  
Elemental Analysis ◽  
Antiradical Activity ◽  
Electronic Spectroscopy ◽  
Antiferromagnetic Exchange ◽  
Dimeric Complexes ◽  
Esi Mass Spectrometry

Two SOD-mimic active dimeric Cu(II) chlorido complexes of the compositions [Cu2(μ-HL1)4Cl2]Cl2(1) and [Cu2(μ-HL2)2(μ-Cl)2(HL2)2Cl2] · 4H2O (2) involving the cosmetologically relevant cytokinin kinetin (N6-furfuryladenine, HL1) and its derivative N6-(5-methylfurfuryl)adenine (HL2) have been synthesized and characterized by elemental analysis, infrared, and electronic spectroscopy, ESI+ mass spectrometry, conductivity and temperature dependence of magnetic susceptibility measurements, and thermogravimetric (TG) and differential thermal (DTA) analyses. The results of these methods, particularly the temperature dependence of magnetic susceptibility, showed the complexes to be dimeric with a strong antiferromagnetic exchange (J= −290 cm−1for complex1andJ= −160 cm−1for2). The complexes have been identified as auspicious SOD-mimics, as their antiradical activity evaluated by thein vitroSOD-mimic assay resulted in the IC50values equal to 8.13 μM (1) and 0.71 μM (2).

Temperature Dependence of the Potency of Volatile General Anesthetics

1996 ◽  
Vol 84 (3) ◽  
pp. 716-720 ◽  
Author(s):  
N. P. Franks ◽  
W. R. Lieb
Keyword(s):  
Temperature Dependence ◽  
Gas Phase ◽  
Aqueous Phase ◽  
Room Temperature ◽  
Minimum Alveolar Concentration ◽  
Volatile Anesthetic ◽  
Published Data ◽  
General Anesthetics ◽  
Target Sites

Background When performing experiments at room temperature with volatile general anesthetics and in vitro mammalian preparations (such as isolated neurons), the question arises as to which concentrations of anesthetics are "clinically relevant." Different choices can lead to different interpretations of the anesthetic sensitivities of putative target sites. Methods Published data on the temperature dependence of minimum alveolar concentration were analyzed. Results Although gas-phase potencies of volatile anesthetics increase markedly with decreasing temperature, the corresponding aqueous-phase potencies are relatively constant. Changes in minimum alveolar concentration with temperature can be accounted for, on physical grounds, in terms of the temperature dependencies of anesthetics binding to their central nervous system target sites. Conclusion When performing room-temperature in vitro experiments on simple mammalian preparations with a volatile anesthetic, the aqueous-phase (but not the gas- phase) minimum alveolar concentration calculated at normal body temperature is, to a first approximation, the appropriate choice for a clinically relevant anesthetic concentration. Recommended aqueous-phase minimum alveolar concentration values (in MM) for desflurane, enflurane, halothane, isoflurane, and sevoflurane have have been calculated.

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