Cellular tolerance to pulsed hyperthermia

Simanovskii, D.; Mackanos, Mark A.; Irani, Afraaz R.; O’Connell‐Rodwell, Caitlin E.; Contag, Christopher H.; Schwettman, H. A.; Palanker, Daniel

doi:10.1103/physreve.74.011915

Cited by 73 publications

(74 citation statements)

References 14 publications

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“…9 Another single-point method for measuring temperature is to focus thermal emission onto a mercury cadmium telluride detector. 10 However, single-point analyses cannot provide complete twodimensional descriptions of heat distribution within a tissue or cell layer and computational models are used to compensate for this inadequacy. 7,8,10 Magnetic resonance thermometry (MRT) has been shown to provide reliable temperature measurements during in vivo interstitial laser coagulation of the canine prostate.…”

Section: Introductionmentioning

confidence: 99%

Spatially correlated microthermography maps threshold temperature in laser-induced damage

Denton¹,

Noojin²,

Foltz³

et al. 2011

J. Biomed. Opt.

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Abstract. We measured threshold temperatures for cell death resulting from short (0.1-1.0 s) 514-nm laser exposures using an in vitro retinal model. Real-time thermal imaging at sub-cellular resolution provides temperature information that is spatially correlated with cells at the boundary of cell death, as indicate by post-exposure fluorescence images. Our measurements indicate markedly similar temperatures, not only around individual boundaries (single exposure), but among all exposures of the same duration in a laser irradiance-independent fashion. Two different methods yield similar threshold temperatures with low variance. Considering the experimental uncertainties associated with the thermal camera, an average peak temperature of 53 ± 2• C is found for laser exposures of 0.1, 0.25, and 1.0 s. Additionally, we find a linear relationship between laser exposure duration and time-averaged integrated temperature. The mean thermal profiles for cells at the boundary of death were assessed using the Arrhenius rate law using parameter sets (frequency factor and energy of activation) found in three different articles. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Section: Introductionmentioning

confidence: 99%

Spatially correlated microthermography maps threshold temperature in laser-induced damage

Denton¹,

Noojin²,

Foltz³

et al. 2011

J. Biomed. Opt.

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“…Cell layers are exposed to short pulses of heat during laser microsurgery procedures such as selective therapy of the retinal pigment epithelium, 11 or tissue surface treatments with a penetration depth of a few micrometers. Similar conditions can also occur in the vicinity of a plasma generated by femtosecond laser-induced dielectric breakdown.…”

Section: Pulse Duration Determines Levels Of Hsp70 Induction In Tissumentioning

confidence: 99%

Pulse duration determines levels of Hsp70 induction in tissues following laser irradiation

Mackanos

Contag

2011

J. Biomed. Opt.

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Abstract. Induction of heat shock protein (Hsp) expression correlates with cytoprotection, reduced tissue damage, and accelerated healing in animal models. Since Hsps are transcriptionally activated in response to stress, they can act as stress indicators in burn injury or surgical procedures that produce heat and thermal change. A fast in vivo readout for induction of Hsp transcription in tissues would allow for the study of these proteins as therapeutic effect mediators and reporters of thermal stress/damage. We used a transgenic reporter mouse in which a luciferase expression is controlled by the regulatory region of the inducible 70 kilodalton (kDa) Hsp as a rapid readout of cellular responses to laser-mediated thermal stress/injury in mouse skin. We assessed the pulse duration dependence of the Hsp70 expression after irradiation with a CO 2 laser at 10.6 μm in wavelength over a range of 1000 to 1 ms. Hsp70 induction varied with changes in laser pulse durations and radiant exposures, which defined the ranges at which thermal activation of Hsp70 can be used to protect cells from subsequent stress, and reveals the window of thermal stress that tissues can endure. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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“…9 Unfortunately, it is known that this model is inaccurate for durations exceeding 1 s, such as femtosecond laser cataract treatments. 10 ANSI standard Z136.1-2007 and ISO 15004-2:2007 give guidance for the safe use of lasers, and both are widely regarded as gold standards for defining safe operation of lasers in medical devices such as for ocular laser surgery. [11][12][13] These standards are based on a collection of published data regarding damage threshold measurements in various animal models.…”

Section: Introductionmentioning

confidence: 99%

Retinal safety of near-infrared lasers in cataract surgery

et al. 2012

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Abstract. Femtosecond lasers have added unprecedented precision and reproducibility to cataract surgery. However, retinal safety limits for the near-infrared lasers employed in surgery are not well quantified. We determined retinal injury thresholds for scanning patterns while considering the effects of reduced blood perfusion from rising intraocular pressure and retinal protection from light scattering on bubbles and tissue fragments produced by laser cutting. We measured retinal damage thresholds of a stationary, 1030-nm, continuous-wave laser with 2.6-mm retinal spot size for 10-and 100-s exposures in rabbits to be 1.35 W (1.26 to 1.42) and 0.78 W (0.73 to 0.83), respectively, and 1.08 W (0.96 to 1.11) and 0.36 W (0.33 to 0.41) when retinal perfusion is blocked. These thresholds were input into a computational model of ocular heating to calculate damage threshold temperatures. By requiring the tissue temperature to remain below the damage threshold temperatures determined in stationary beam experiments, one can calculate conservative damage thresholds for cataract surgery patterns. Light scattering on microbubbles and tissue fragments decreased the transmitted power by 88% within a 12 deg angle, adding a significant margin for retinal safety. These results can be used for assessment of the maximum permissible exposure during laser cataract surgery under various assumptions of blood perfusion, treatment duration, and scanning patterns.

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Cellular tolerance to pulsed hyperthermia

Cited by 73 publications

References 14 publications

Spatially correlated microthermography maps threshold temperature in laser-induced damage

Spatially correlated microthermography maps threshold temperature in laser-induced damage

Pulse duration determines levels of Hsp70 induction in tissues following laser irradiation

Retinal safety of near-infrared lasers in cataract surgery

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