Thermal analysis of CHL V79 cells using differential scanning calorimetry: Implications for hyperthermic cell killing and the heat shock response

Lepock, James R.; Frey, H.E.; Rodahl, A. Michael; Kruuv, J.

doi:10.1002/jcp.1041370103

Cited by 125 publications

(83 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Differential scanning calorimetry (DSC) is a thermal-analysis technique that has become a powerful tool for detecting and quantifying thermotropic transitions of various materials (10,13). The DSC method is usually used to characterize isolated biopolymers and macromolecular assemblies but has also been applied successfully to characterize more complex systems such as mammalian cells (24,25,27), bacterial vegetative cells (2,9,26,30,31,37,46), and bacterial spores (32)(33)(34)37). DSC can be used to determine the enthalpy of a thermally induced transition by measuring the differential heat flow required to maintain a sample and an inert reference at the same temperature.…”

mentioning

confidence: 99%

Heat killing of bacterial spores analyzed by differential scanning calorimetry

et al. 1992

View full text Add to dashboard Cite

Thermograms of the exosporium-lacking dormant spores of Bacillus megaterium ATCC 33729, obtained by differential scanning calorimetry, showed three major irreversible endothermic transitions with peaks at 56, 100, and 114°C and a major irreversible exothermic transition with a peak at 119°C. The 114°C transition was identified with coat proteins, and the 56°C transition was identified with heat inactivation. Thermograms of the germinated spores and vegetative cells were much alike, including an endothermic transition attributable to DNA. The ascending part of the main endothermic 100°C transition in the dormant-spore thermograms corresponded to a first-order reaction and was correlated with spore death; i.e., >99.9%o of the spores were killed when the transition peak was reached. The maximum death rate of the dormant spores during calorimetry, calculated from separately measured D and z values, occurred at temperatures above the 73°C onset of thermal denaturation and was equivalent to the maximum inactivation rate calculated for the critical target. Most of the spore killing occurred before the release of most of the dipicolinic acid and other intraprotoplast materials. The exothermic 119°C transition was a consequence of the endothermic 100°C transition and probably represented the aggregation of intraprotoplast spore components. Taken together with prior evidence, the results suggest that a crucial protein is the rate-limiting primary target in the heat killing of dormant bacterial spores.How do bacterial spores resist heat, and, conversely, how are they killed when their thermal-defense mechanisms are overcome? Answering these two questions is fundamentally important to practical solutions of food spoilage, food poisoning, and infectious disease in which spores are causative. Furthermore, much of microbiological practice depends on heat sterilization, which is predicated on killing all spores in the material.The question of heat resistance mechanisms now seems mainly answered as follows: bacterial spores are able to resist heat because their protoplasts have become dehydrated to a water content that is low enough to immobilize and therefore to protect the vital macromolecules (e.g., proteins, RNA, and DNA) from denaturation and the supramolecular assemblies (e.g., membranes and ribosomes) from disruption. Although dehydration is the only property necessary and sufficient in itself to impart heat resistance, it is enhanced by mineralization (especially by calcification) and thermal adaptation. The physiological processes by which the spore attains the resistant state are less well understood, but the retention of resistance clearly is a function of an intact peptidoglycan cortex encasing the protoplast. The experimental evidence supporting these assertions has been reviewed by Gerhardt and Marquis (19).The question of heat killing mechanisms, however, remains mainly unanswered. In an effort to obtain experimental evidence about these mechanisms, we undertook the study of a selected spore morphotype, Bacillus m...

show abstract

mentioning

confidence: 99%

Heat killing of bacterial spores analyzed by differential scanning calorimetry

et al. 1992

View full text Add to dashboard Cite

show abstract

“…The rate coefficient of protein misfolding ϕ(T ) with respect to temperature T has been investigated experimentally in [12,13], and a mathematical expression describing the relation has been proposed in [11]. After adapting this formula in [11] to the time unit of our mathematical model (second), we obtain the following misfolding rate coefficient:…”

Section: The Heat Shock Response Modelmentioning

confidence: 99%

Computational Heuristics for Simplifying a Biological Model

Petre

Mizera

Back

2009

Mathematical Theory and Computational Practice

View full text Add to dashboard Cite

Abstract. Computational biomodelers adopt either of the following approaches: build rich, as complete as possible models in an effort to obtain very realistic models, or on the contrary, build as simple as possible models focusing only on the core aspects of the process, in an effort to obtain a model that is easier to analyze, fit, and validate. When the latter strategy is adopted, the aspects that are left outside the models are very often up to the subjective options of the modeler. We discuss in this paper a heuristic method to simplify an already fit model in such a way that the numerical fit to the experimental data is not lost. We focus in particular on eliminating some of the variables of the model and the reactions they take part in, while also modifying some of the remaining reactions. We illustrate the method on a computational model for the eukaryotic heat shock response. We also discuss the limitations of this method.

show abstract

“…6 While temperatures of 41°C can be achieved clinically, administration of higher temperatures can be challenging. In order to overcome this problem we have undertaken a chemistry-driven approach to identify pharmacological agents that enhance the degree of radiosensitization produced by a moderate heat shock.…”

Section: Nih Public Accessmentioning

confidence: 99%

“…Subsequent investigations have validated their hypothesis. [6][7][8] Thermal radiosensitization is also a consequence of protein unfolding and aggregation, 4 and under most conditions, is directly related to the degree of thermal sensitization.…”

mentioning

confidence: 99%

Novel substituted (Z)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-one and (Z)-(±)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ol derivatives as potent thermal sensitizing agents

Sonar

Reddy

Sekhar

et al. 2007

Bioorganic & Medicinal Chemistry Letters

View full text Add to dashboard Cite

Use of ionizing radiation is essential for the management of many human cancers, and therapeutic hyperthermia has been identified as a potent radiosensitizer. Radiation therapy combined with adjuvant hyperthermia represents a potential tool to provide outstanding local-regional control for refractory disease. (Z)-(±)-2-(N-Benzylindol-3-ylmethylene)quinuclidin-3-ol (2) and (Z)-(±)-2-(Nbenzenesulfoylindol-3-ylmethylene)quinuclidin-3-ol (4) were initially identified as potent thermal sensitizers that could lower the threshold needed for thermal sensitivity to radiation treatment. To define the structural requirements of the molecule that are essential for thermal sensitization, we have synthesized and evaluated a series of (Z)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-one (9), and (Z)-(±)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ol (10) analogs that incorporate a variety of substituents in both the indole and N-benzyl moieties. These systematic structureactivity relationship (SAR) studies were designed to further the development and optimization of potential clinically useful thermal sensitizing agents. The most potent analog was compound 10 (R 1 =H, R 2 =4-Cl), which potently inhibited (93% inhibition at 50 µM) the growth of HT-29 cells after a 41°C/2hr exposure. Keywordsindolylquinuclidin-3-ones; indolylquinuclidin-3-ols; thermal sensitization Hyperthermia is one of the most potent radiosensitizers identified to date 1 . Over the last 30 years extensive experimentation using cell and animal models has demonstrated that hyperthermia can be an extremely effective radiation sensitizer, increasing the effectiveness of the radiation by up to 5-fold. 1,2 One important feature is that thermal radiosensitization does not exhibit cell type specificity nor is it limited by hypoxic conditions, suggesting that Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Heat-mediated changes in protein conformation represent the underlying biophysical/ biochemical mechanism responsible for heat-mediated cytotoxicity. 4 Westra and Dewey 5 were the first to hypothesize that cell death following hyperthermic treatment was a consequence of protein denaturation. Subsequent investigations have validated their hypothesis. 6-8 Thermal radiosensitization is also a consequence of protein unfolding and aggregation, 4 and under most conditions, is directly related to the degree of thermal sensitization. NIH Public AccessHowever, for many cancers, suboptimal thermal dosing limits radiosensitization. 6 While temperatures of 41°C can be achieved clinically, administration of higher temperatures ca...

show abstract

Thermal analysis of CHL V79 cells using differential scanning calorimetry: Implications for hyperthermic cell killing and the heat shock response

Cited by 125 publications

References 29 publications

Heat killing of bacterial spores analyzed by differential scanning calorimetry

Heat killing of bacterial spores analyzed by differential scanning calorimetry

Computational Heuristics for Simplifying a Biological Model

Novel substituted (Z)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-one and (Z)-(±)-2-(N-benzylindol-3-ylmethylene)quinuclidin-3-ol derivatives as potent thermal sensitizing agents

Contact Info

Product

Resources

About