Wyniki wyszukiwania - BazTech

1

Modelowanie biofizyczne popromiennego efektu sąsiedztwa – część II

Wysocki Paweł, Fornalski Krzysztof W.

Postępy Techniki Jądrowej

|

2021

|

z. 3

25--33

PL

Powszechnie wiadomo, że promieniowanie jonizujące może wywoływać uszkodzenia w komórkach, które z nim bezpośrednio oddziaływały. Jednakże ostatnie badania wykazały, że uszkodzenia pojawiają się również w komórkach, które nie doświadczyły bezpośredniej interakcji. Jest to związane z występowaniem tak zwanego efektu sąsiedztwa (ang. bystander effect), który polega na wysyłaniu przez komórkę napromienioną sygnałów, które mogą uszkadzać komórki sąsiednie. Ze względu na złożoność tego efektu, nie jest on prosty do ścisłego biofizycznego opisu, a co za tym idzie, także do symulacji. W niniejszym artykule przedstawiony został przegląd różnych podejść do modelowania i symulowania efektu sąsiedztwa z punktu widzenia biofizyki radiacyjnej (część I). W szczególności ostatni z przedstawionych modeli jest częścią większego projektu symulacji odpowiedzi grupy komórek na promieniowanie jonizujące z wykorzystaniem metod Monte Carlo (część II).

EN

It is well known that ionizing radiation can cause damages to cells that interact with it directly. However, recent studies have shown that damages also occur in cells that have not experienced direct interaction. This is due to the so-called bystander effect, which is observed when the irradiated cell sends signals that can damage neighboring cells. Due to the complexity of this effect, it is not easy to strictly describe it biophysically, and thus also to simulate. This article reviews various approaches to modeling and simulating the bystander effect from the point of view of radiation biophysics (Part I). In particular, the last model presented within this article is part of a larger project of modeling the response of a group of cells to ionizing radiation using Monte Carlo methods (Part II).

2

Modelowanie biofizyczne popromiennego efektu sąsiedztwa – część I

Wysocki Paweł, Fornalski Krzysztof W.

Postępy Techniki Jądrowej

|

2021

|

z. 2

27--36

PL

Powszechnie wiadomo, że promieniowanie jonizujące może wywoływać uszkodzenia w komórkach, które z nim bezpośrednio oddziaływały. Jednakże ostatnie badania wykazały, że uszkodzenia pojawiają się również w komórkach, które nie doświadczyły bezpośredniej interakcji. Jest to związane z występowaniem tak zwanego efektu sąsiedztwa (ang. bystander effect), który polega na wysyłaniu przez komórkę napromienioną sygnałów, które mogą uszkadzać komórki sąsiednie. Ze względu na złożoność tego efektu, nie jest on prosty do ścisłego biofizycznego opisu, a co za tym idzie, także do symulacji. W niniejszym artykule przedstawiony został przegląd różnych podejść do modelowania i symulowania efektu sąsiedztwa z punktu widzenia biofizyki radiacyjnej (część I). W szczególności ostatni z przedstawionych modeli jest częścią większego projektu symulacji odpowiedzi grupy komórek na promieniowanie jonizujące z wykorzystaniem metod Monte Carlo (część II).

EN

It is well known that ionizing radiation can cause damages to cells that interact with it directly. However, recent studies have shown that damages also occur in cells that have not experienced direct interaction. This is due to the so-called bystander effect, which is observed when the irradiated cell sends signals that can damage neighboring cells. Due to the complexity of this effect, it is not easy to strictly describe it biophysically, and thus also to simulate. This article reviews various approaches to modeling and simulating the bystander effect from the point of view of radiation biophysics (Part I). In particular, the last model presented within this article is part of a larger project of modeling the response of a group of cells to ionizing radiation using Monte Carlo methods (Part II).

3

The role of the spatially fractionated radiation therapy in the management of advanced bulky tumors

Mahmoudi Farshid, Shahbazi-Gahrouei Daryoush, Chegeni Nahid

Polish Journal of Medical Physics and Engineering

|

2021

|

Vol. 27, Iss. 2

123--135

EN

Spatially fractionated radiation therapy (SFRT) refers to the delivery of a single large dose of radiation within the target volume in a heterogeneous pattern using either a custom GRID block, multileaf collimators, and virtual methods such as helical tomotherapy or synchrotron-based microbeams. The potential impact of this technique on the regression of bulky deep-seated tumors that do not respond well to conventional radiotherapy has been remarkable. To date, a large number of patients have been treated using the SFRT techniques. However, there are yet many technical and medical challenges that have limited their routine use to a handful of clinics, most commonly for palliative intent. There is also a poor understanding of the biological mechanisms underlying the clinical efficacy of this approach. In this article, the methods of SFRT delivery together with its potential biological mechanisms are presented. Furthermore, technical challenges and clinical achievements along with the radiobiological models used to evaluate the efficacy and safety of SFRT are highlighted.

4

Spatial evolutionary games and radiation induced bystander effect

Krześlak M., Świerniak A.

Archives of Control Sciences

|

2011

|

Vol. 21, no. 2

135-150

EN

We present an application of evolutionary game theory to modeling of some processes important from oncological point of view. A studied phenomenon is a radiation induced bystander effect, in which three different strategies (phenotypes) of cells take part. The proposed payoff table of fitness, related to environment adaptation and genetic cell behavior, contains costs/profits of bystander effect, choice of apoptotic pathway, producing growth factors and resistance against bystander effect. We consider a game theory model including spatial cells allocation (the game is played on lattice). We discuss also different polymorphic equilibrium points dependent on model parameters, types of spatial games and players distribution.

5

Medium-mediated bystander response of X-ray-irradiated normal human lymphocytes in vitro

Konopacka M.

Nukleonika

|

2008

|

Vol. 53, suppl. 1

5-8

EN

Radiation-induced bystander effects occur in cells that are not directly irradiated but that communicate with irradiated cells via secreted into culture medium soluble factors or gap junction. This effect induces in irradiated and neighboring cells persistent long-term changes that result in delayed death or genomic instability leading to neoplastic transformation. Non-irradiated human normal lymphocytes were incubated in a medium transferred from irradiated another samples of lymphocytes (ICM - irradiation-conditioned medium). Immediately after replacement of the normal or conditioned medium antioxidant vitamins C or E were added. In lymphocytes incubated in a normal medium (control) or conditioned medium, with or without vitamins, the chromosomal damage and apoptosis were estimated. The results show that medium from irradiated cells (ICM) induces in normal lymphocytes micronuclei and condensation of chromatin characteristic of processes of apoptosis. Conditioned medium did not influence cell cycle division. Bystander effect-induced formation of micronuclei was inhibited by antioxidant vitamins C and E, but this had no effect on the induction of apoptosis. These observations suggest that antioxidant vitamins are able to modify radiation-induced bystander effect (by preventing the increase in micronuclei), without inhibiting elimination of damaged cells via apoptosis. This finding could have significant implication for estimating risks of radiation exposure.

6

The bystander effect: is reactive oxygen species the driver?

Szumiel I.

Nukleonika

|

2003

|

Vol. 48, nr 3

113-120

EN

The paper reviews selected examples of the bystander effect, such as clonogenic survival decrease, chromosomal aberrations and mutations. The similarities and differences between the biological effects in directly targeted and bystander cells are briefly discussed. Also reviewed are the experimental data which support the role of reactive oxygen species (ROS), especially *O2-, as mediators of the bystander effect. Endogenously generated ROS, due to activation of NAD(P)H oxidases, play a key role in the induction of DNA damage in bystander cells. All the observed effects in bystander cells, such as alterations in gene expression patterns, chromosomal aberrations, sister chromatid exchanges, mutations, genome instability, and neoplastic transformation are the consequence of DNA damage.