ヒトの放射線原性遺伝学における線量効果の依存性

THE DEPENDENCE OF DOSE-EFFECTS IN HUMAN RADIATION CYTOGENETICS.

• E A Djomina

抄録

目的:

ヒト末梢血リンパ球における染色体異常の頻度とスペクトルを、放射線量、有糸分裂周期の段階、細胞培養の固定期間に依存して研究する。

OBJECTIVE: To study the frequency and spectrum of chromosome aberrations in human peripheral blood lymphocytes depending on the radiation dose, the stage of the mitotic cycle and the periods of fixation of the cell culture.

材料と方法:

ドナーの血液リンパ球の検査系、染色体異常のメタフェース解析（薬剤の均一な染色）を行った。ガンマ線照射は、線源60Coを用いた装置で0.5Gy/min、線量範囲は0.25〜4.0Gyで行った。リンパ球培養は、培養開始から0時間後、24時間後、40時間後、48時間後に照射したが、これはmitot-icサイクルのG0-、G1-、S-、G2ステージに相当する。インキュベーション開始から52時間後と62時間後に細胞を固定した。

MATERIALS AND METHODS: The test system of blood lymphocytes of donors, the metaphase analysis of chromosome aberrations (a uniform staining of the drugs). The gamma-irradiation was performed on the device with the source 60Co at the dose rate of 0.5 Gy/min, the dose range was 0.25-4.0 Gy. The lymphocyte culture was irradiated after 0, 24, 40 and 48 hours from the beginning of the incubation, which corresponds to G0-, G1-, S-, G2-stages of the mitot- ic cycle. The cells were fixed after 52 hours and 62 hours from the beginning of the incubation.

結果:

ヒト末梢血リンパ球培養の分裂周期の異なる時期における照射中の染色体異常形成の規則性について、筆者らの実験データを紹介する。線形モデル,二乗モデル,放物線モデルを用いて、有糸分裂周期における染色体の構造的損傷の線量依存性を解析した。交換型異常の最大の収量は、有糸分裂周期のG0期とG1期に照射されたときに記録され、照射線量に線形二乗依存性を示す。S期とG2期の細胞に放射線を照射した場合、放射線誘発染色体異常のスペクトルへの主な寄与は欠失によるものであり、そのレベルは線量に比例して直線的に増加する。このことは、これらのステージの回帰式の二次項の負の値によって証明されています。放物線モデルY = k - Dnを用いて曲線を解析したところ、G0およびG1期のリンパ球の照射では、線量依存性が2次曲線に近づくことが示された。しかし、低線量照射領域における細胞遺伝学的効果の依存性の近似については、スプライン回帰モデルの方がより正確である。

RESULTS: The author's experimental data on the regularities of chromosome aberrations formation during irradiation at the different periods of the mitotic cycle of human lymphocyte culture are presented. The character of the dose dependences of structural damages of chromosomes during the mitotic cycle with an application of the linear, lin- ear-square and parabolic models is analyzed. The greatest yield of exchange-type aberrations is registered at the irradiation in G0- and G1-stages of the mitotic cycle, which submits to the linear-square dependence on an irradia- tion dose. When irradiating cells in the S- and G2-stages, the main contribution to the spectrum of radiation-induced chromosome aberrations is made by deletions, the level of which increases linearly with the dose. This is evidenced by the negative values of the quadratic term in the regression equations for these stages. The analysis of the curves using the parabolic model Y = k · Dn has shown that, at the irradiation of lymphocytes in G0- and G1-stages, the dose dependences approach the quadratic ones, which confirms the reasonableness of the interpretation of the obtained cytogenetic data from the point of view of the «classical» theory of the radiation-induced chromosome aberrations formation. However, the model of the spline regression is more accurate at the approximation of the dependences of the cytogenetic effects in the region of low doses of irradiation.

結論:

ヒトリンパ球の細胞周期の異なる段階での照射により得られた結果は、同じ放射線量でも照射時の細胞の生理的状態に応じて、質的及び量的に異なる細胞遺伝学的効果が誘導されることを示している。照射線量率，分裂周期の段階，照射後の条件，個々の放射線感受性などの要因の組み合わせは，細胞の放射線感受性の定量的・定性的な変化に反映される。

CONCLUSIONS: The results obtained by the irradiation of human lymphocyte culture at different stages of the mitot- ic cycle indicate that the same radiation dose induces different qualitative and quantitative cytogenetic effects depending on the physiological state of the cell at the time of irradiation. The combination of such factors as a radi- ation dose rate, a mitotic cycle stage, the post-irradiation conditions, and an individual radiosensitivity are reflect- ed in quantitative and qualitative variations of the cellular radiosensitivity.

Meta: vyvvchyty chastotu i spektr aberatsiyy̆ khromosom v limfotsytakh peryferychnoï krovi liudyny zalezhno vid dozy oprominennia, stadiï mitotychnogo tsyklu i terminiv fiksatsiï kul'tury klityn.Materialy i metody.Metaly i metody.Test-systema limfotsytiv krovi donoriv, metafaznyyy̆ analiz aberatsiy̆ khromosom (rivnomirne farbuvannia preparativ).γ-oprominennia vыpykonano na ustanovtsi z dzherelom 60Co za potuzh-nosti dozy 0,5 Gr/khv, diapazon doz skladav 0,25-4,0 Gr.Fiksatsiiu klityn provodyly cherez 52 god i 62 god vid pochatku inkubatsiï.Rezul'taty.Vykladeno eksperymental'ni dani avtora shchodo zakonomirnostey̆ utvorennia aberatsiyy̆ khromosom pry oprominenni v rizni peri mitotychnogo tsyklu kul'tury limfotsytiv liudyny.吊り下げ式の吊り下げ式の場合は、吊り下げたままの状態ではなく、吊り下げたままの状態での吊り下げ式になります。Nay̆bil'shyy̆ vykhid aberatsiy̆ obminnogo typu reiestruiet'sia pry op- rominenni v G0- i G1-stadiïﾐﾁｭｰﾄﾁｪｯｸﾉｺﾞｳﾉｺﾞｳﾞｳﾞｨｴｯﾄｽのためには、そのようにしなければなりません。Pry oprominenni klityn v S- i G2-stadiï osnovnyy̆ vnesok u spektr radiatsiy̆no-indukovanykh abe ratsiy̆ khromosom vnosiat' deletsiï, riven' iakykh zrostaie liniy̆no z do doiu.そのような場合は、そのようなことをしないでください。Analiz kryvykh z vykorystanniam parabolichnoï modeli Y = k - Dn pokazav, shcho pry oprominenni limfotsytiv v G0- i G1-stadiï dozovi zalezhnosti nablyzhaiut'sia do kvadra- tychnykh, shcho pidtverdzhuie pravomochnist' interpretatsiïotrymanykh tsytogenetychnykh danykh z pozytsiï "klasychnoï" te oriï utvorennia radiatsiy̆no-indukovanykh aberatsiy̆ khromosom.Odnak tochnisha aproksymatsiia zalezhnostey̆ tsytoge-netychnykh efektiv v oblasti malykh doz oprominennia dosiagaiet'sia z vykorystanniam modeli splay̆novoï regresiï.Vysnovky.Rezul'taty, otrymani pry oprominenni kul'tury limfotsytiv liudyny v rizni stadiï mitotychnogo tsyklu, svidchat' pro te, shcho odna y̆ ta zh doza radiatsiïindukuie riznyyy̆ iakisnyy̆ i kil'kisnyy̆ tsytogenetychnyy̆ efekt zalezh- no vid fiziologichnogo stanu klityny v moment oprominennia.Poiednannia takykh faktoriv, iak velychyna dozy radia- tsiï, stadiia mitotychnogo tsyklu, postpromenevi umovy, indyvidual'na radiochutlyvist', vidobrazhaiet'sia na kil'- kisniy̆ iakisniy̆ variatsiiakh radiochutlyvosti klityn.

Meta: vyvchyty chastotu i spektr aberatsiy̆ khromosom v limfotsytakh peryferychnoï krovi liudyny zalezhno vid dozy oprominennia, stadiï mitotychnogo tsyklu i terminiv fiksatsiï kul'tury klityn.Materialy i metody. Test-systema limfotsytiv krovi donoriv, metafaznyy̆ analiz aberatsiy̆ khromosom (rivnomirne farbuvannia preparativ). Gamma-oprominennia vыpykonano na ustanovtsi z dzherelom 60Co za potuzh- nosti dozy 0,5 Gr/khv, diapazon doz skladav 0,25–4,0 Gr. Kul'turu limfotsytiv oprominiuvaly cherez 0, 24, 40 i 48 god vid pochatku inkubatsiï, shcho vidpovidaie G0-, G1-, S-, G2-stadiiam mytotychnogo tsyklu. Fiksatsiiu klityn provodyly cherez 52 god i 62 god vid pochatku inkubatsiï.Rezul'taty. Vykladeno eksperymental'ni dani avtora shchodo zakonomirnostey̆ utvorennia aberatsiy̆ khromosom pry oprominenni v rizni periody mitotychnogo tsyklu kul'tury limfotsytiv liudyny. Proanalizovano kharakter dozovykh zalezhnostey̆ strukturnykh poshkodzhen' khromosom protiagom mitotychnogo tsyklu iz zastosuvanniam liniy̆noï, liniy̆no-kvadratychnoï i parabolichnoï modeley̆. Nay̆bil'shyy̆ vykhid aberatsiy̆ obminnogo typu reiestruiet'sia pry op- rominenni v G0- i G1-stadiï mitotychnogo tsyklu, iakyy̆ pidporiadkovuiet'sia liniy̆no-kvadratychniy̆ zalezhnosti vid do- zy oprominennia. Pry oprominenni klityn v S- i G2-stadiï osnovnyy̆ vnesok u spektr radiatsiy̆no-indukovanykh abe- ratsiy̆ khromosom vnosiat' deletsiï, riven' iakykh zrostaie liniy̆no z dozoiu. Pro tse svidchat' negatyvni znachennia kvad- ratychnogo chlena v regresiy̆nykh rivnianniakh dlia tsykh stadiy̆. Analiz kryvykh z vykorystanniam parabolichnoï modeli Y = k · Dn pokazav, shcho pry oprominenni limfotsytiv v G0- i G1-stadiï dozovi zalezhnosti nablyzhaiut'sia do kvadra- tychnykh, shcho pidtverdzhuie pravomochnist' interpretatsiï otrymanykh tsytogenetychnykh danykh z pozytsiï «klasychnoï» te- oriï utvorennia radiatsiy̆no-indukovanykh aberatsiy̆ khromosom. Odnak tochnisha aproksymatsiia zalezhnostey̆ tsytoge- netychnykh efektiv v oblasti malykh doz oprominennia dosiagaiet'sia z vykorystanniam modeli splay̆novoï regresiï. Vysnovky. Rezul'taty, otrymani pry oprominenni kul'tury limfotsytiv liudyny v rizni stadiï mitotychnogo tsyklu, svidchat' pro te, shcho odna y̆ ta zh doza radiatsiï indukuie riznyy̆ iakisnyy̆ i kil'kisnyy̆ tsytogenetychnyy̆ efekt zalezh- no vid fiziologichnogo stanu klityny v moment oprominennia. Poiednannia takykh faktoriv, iak velychyna dozy radia- tsiï, stadiia mitotychnogo tsyklu, postpromenevi umovy, indyvidual'na radiochutlyvist', vidobrazhaiet'sia na kil'- kisniy̆ i iakisniy̆ variatsiiakh radiochutlyvosti klityn.

E. A. Djomina.