hyperthermia
(rus. гипертермия otherwise повышенная температура тела)
—
heating of an organism or part thereof above the physiological norm.
Description
The physiological norm of human body temperature is around 37°C. In warm-blooded animals it can be higher, for example, 39-40°C for pigs and 40-43°C for birds. Hyperthermia occurs as a result of imbalance between metabolic heat production and the heat dissipation mechanisms of an organism, such as sweating, rapid breathing, intense blood circulation in skin vessels. Hyperthermia is a natural protective reaction of the body, for example, to infections.
Hyperthermia can be created artificially by increasing external heat supply and restricting heat dissipation.
Several methods for treating various diseases with use of controlled local or general hyperthermia have been proposed. If human body is overheated above 42°C this leads to significant damage of life support systems and causes heat stroke. Further temperature increase causes irreversible damage to the structure and functions of an organism’s proteins incompatible with life. Therefore methods of local hyperthermia have drawn more attention, although most of them are still at the stage of preclinical development or clinical trials.
The simplest variant of local hyperthermia is heating with the use of a metal needle introduced into the affected area; another option is focusing microwave radiation at the affected area. Various methods of local magnetic hyperthermia are now under active development; in these methods magnetic material introduced into the affected area is heated externally using electromagnetic radiation in the range of 100-800 kHz, which is practically not absorbed by body tissues, but strongly interacts with ferro- and super-paramagnetics. Nanoparticles of iron oxides and various alloys that are potentially capable of penetrating into cells, or larger submicron particles of biocompatible ferromagnetics located in the intercellular space may be used for magnetic hyperthermia. As control over the distribution of such particles between healthy and damaged tissues can be difficult, it can lead to overheating of healthy tissues. To solve this problem, magnetic particles with low Curie temperature were suggested, in which heating automatically stops upon reaching a defined temperature. Another possibility is the vectorisation of nanoparticles (e.g. by antibodies) for their targeted delivery to the affected cells.
The methods of local hyperthermia are close to the methods of photodynamic therapy, which exploits the transparency window of body tissues in the near infra-red region and high absorption of infra-red radiation by gold nanoparticles and phthalocyanines introduced into the affected area as local mediators of heating. Effects of intense ultrasound can be localisised in the body with use of solid particles, either introduced into the affected area, or synthesised within it.
Thermoablation (thermocoagulation) therapy is local hyperthermia for the destruction of affected tissues.
Hyperthermia can be created artificially by increasing external heat supply and restricting heat dissipation.
Several methods for treating various diseases with use of controlled local or general hyperthermia have been proposed. If human body is overheated above 42°C this leads to significant damage of life support systems and causes heat stroke. Further temperature increase causes irreversible damage to the structure and functions of an organism’s proteins incompatible with life. Therefore methods of local hyperthermia have drawn more attention, although most of them are still at the stage of preclinical development or clinical trials.
The simplest variant of local hyperthermia is heating with the use of a metal needle introduced into the affected area; another option is focusing microwave radiation at the affected area. Various methods of local magnetic hyperthermia are now under active development; in these methods magnetic material introduced into the affected area is heated externally using electromagnetic radiation in the range of 100-800 kHz, which is practically not absorbed by body tissues, but strongly interacts with ferro- and super-paramagnetics. Nanoparticles of iron oxides and various alloys that are potentially capable of penetrating into cells, or larger submicron particles of biocompatible ferromagnetics located in the intercellular space may be used for magnetic hyperthermia. As control over the distribution of such particles between healthy and damaged tissues can be difficult, it can lead to overheating of healthy tissues. To solve this problem, magnetic particles with low Curie temperature were suggested, in which heating automatically stops upon reaching a defined temperature. Another possibility is the vectorisation of nanoparticles (e.g. by antibodies) for their targeted delivery to the affected cells.
The methods of local hyperthermia are close to the methods of photodynamic therapy, which exploits the transparency window of body tissues in the near infra-red region and high absorption of infra-red radiation by gold nanoparticles and phthalocyanines introduced into the affected area as local mediators of heating. Effects of intense ultrasound can be localisised in the body with use of solid particles, either introduced into the affected area, or synthesised within it.
Thermoablation (thermocoagulation) therapy is local hyperthermia for the destruction of affected tissues.
Illustrations
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Схематическое изображение ферромагнитных наночастиц, покрытых декстрановой оболочкой, которые могут накапливаться в раковых клетках и при нагреве в переменном магнитном поле уничтожать опухоль [6]. |
Authors
- Shirinsky Vladimir P.
- Shlyakhtin Oleg A.
Sources
- Moroz P., Jones S.K., Gray B. N. Magnetically mediated hyperthermia: current status and future directions // Int. J. Hyperthermia. 2004. V. 18, №4. P. 267–284.
- Jordan A., Scholz R., Maier-Hauff K. et al. Presentation of a new magnetic field therapy system for the treatment of human solid tumors with magnetic fluid hyperthermia // J. Magn. Mater. 2001. V 225. P. 118–126.
- Kuznetsov A. A., Shlyakhtin O. A., Brusentsov N. A., Kuznetsov O. A. «Smart» mediators for selfcontrolled inductive heating // European Cells and Materials. 2002. V. 3. P. 75–77.
- Salmin R.M., Sten'ko A. A., Zhuk I. G., Bragov M.Ju. Main trends in photodynamic therapy in medicine (in Russian) // Novosti khirurgii. 2008. V. 16. 155–162 pp.
- Nikolaev A. L., Gopin A. V., Bozhevol'nov V. E. et al. The use of solid-phase inhomogeneities to improve ultrasound cancer therapy (in Russian) // Akusticheskijj zhurnal. 2009. V. 55, #4–5. 565–574 pp.
- Dennis C. L., Jackson A. J., Borchers J. A. et al. Nearly complete regression of tumors via collective behavior of magnetic nanoparticles in hyperthermia // Nanotechnology. 2009. V. 20, №39. Paper 395 103.