Induction of sister chromatid exchanges by UV light and its inhibition by caffeine

Kato, Hatao

doi:10.1016/0014-4827(73)90356-x

Cited by 173 publications

(30 citation statements)

References 25 publications

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“…The responses of AT cells to ionizing radiation are very similar to those observed when other mammalian cells are irradiated in the presence of caffeine, which (i) prevents inhibition of DNA synthesis (17) by reversing the block to replicon initiation (1)(2)(3)(4)(5)(6)(7)(8), (ii) shortens mitotic delay (19), (iii) increases the incidence of chromosomal aberrations (20), and (iv) enhances cell killing (21,22 …”

Section: Discussionmentioning

confidence: 53%

Radiosensitivity in ataxia-telangiectasia: a new explanation.

Painter¹,

Young²

1980

Proc. Natl. Acad. Sci. U.S.A.

681

325

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The cause of increased radiosensitivity in ataxia-telangiectasia (AT) cells may be a defect in their ability to respond to DNA damage rather than a defect in their ability to repair it. Doses of x-radiation that markedly inhibited the rate of DNA synthesis in normal human cells caused almost no inhibition in AT cells and thus less delay during which x-ray damage could be repaired. The radioresistance of DNA synthesis in AT cells was primarily due to a much smaller inhibition of replicon initiation than in normal cells; the AT cells were also more resistant to damage that inhibited chain elongation. AT cells have been reported to undergo less radiation-induced mitotic delay than normal cells, which may cause them to move from G2 phase into mitosis before repair is complete and may result in the increased incidence of chromatid aberrations observed by others. Therefore, AT cells fail to go through those delays that allow normal cells to repair DNA damage before it can be expressed.

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Section: Discussionmentioning

confidence: 53%

Radiosensitivity in ataxia-telangiectasia: a new explanation.

Painter¹,

Young²

1980

Proc. Natl. Acad. Sci. U.S.A.

681

325

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“…In this case, chromosomal aberrations are postulated to occur in damaged chromatin owing to interference of caffeine with replication of damaged DNA strands (daughter strand repair, "postreplication repair"; Kihlman et al, 1974;Roberts et al, 1974;Nilsson and Lehmann, 1975;Kihlman, 1977;Roberts, 1978). A particular characteristic of this system is the frequent and abrupt appearance of metaphase plates, in which all chromosomes are shattered (generalized chromosome shattering, GCS), while other metaphase plates remain intact or show single chromosomal aberrations (Kato, 1973;Roberts et al, 1974;Nilsson and Lehmann, 1975;C. Cremer et al, 1980b).…”

Section: Discussionmentioning

confidence: 99%

Induction of chromosome shattering by ultraviolet irradiation and caffeine: comparison of whole cell and partial-cell irradiation

Cremer

Zorn

et al. 1981

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

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SummarySynchronized and asynchronously growing cells of a V79 sub-line of the Chinese hamster were either whole-cell irradiated (~,, 254 nm) or laser-UV-microirradiated ()~, 257 nm). Post-incubation with caffeine (1-2 mM) often resulted in chromosome shattering, which was a rare event in the absence of this compound. In experiments with caffeine, the following results were obtained.Shattering of all the chromosomes of a cell (generalized chromosome shattering, GCS) was induced by whole-cell irradiation at the first post-irradiation mitosis when the UV fluence exceeded a "threshold" value in the sensitive phases of the cell cycle (.(31 and S). GCS was also induced by laser-UV-microirradiation of a small part of the nucleus in G1 or S whereas microirradiation of cytoplasm beside the nucleus was not effective. An upper limit of the UV fluence in the non-irradiated nuclear part due to scattering of the microbeam was experimentally obtained. This UV fluence was significantly below the threshold fluence necessary to induce GCS in whole-cell irradiation experiments. In other cells, partial nuclear irradiation resulted in shattering of a few chromosomes only, while the majority remained intact (partial chromosome shattering, PCS). G1/early S was the most sensitive phase for induction of GCS by whole-cell and partial nuclear irradiation. The frequency of PCS was observed to increase when partial nuclear irradiation was performed either at lower incident doses or at later stages of S. We suggest that PCS and GCS indicate 2 levels of chromosome damage which can be produced by the synergistic action of UV irradiation and caffeine. PCS may be restricted to microirradiated chromatin whereas

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“…Ultraviolet light, which is a form of visible light, and phototherapy light have been shown to damage DNA in vitro and in vivo [37][38][39][40][41][42]. However, some studies reported that phototherapy light has no significant impact on nuclear material [43,44].…”

Section: Discussionmentioning

confidence: 99%

Once the Light Touch to the Brain: Cytotoxic Effects of Low-Dose Gamma-Ray, Laser Light, and Visible Light on Rat Neuronal Cell Culture

et al. 2016

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Objective: We aimed to evaluate the effects of gamma-ray, laser light, and visible light, which neurons are commonly exposed to during treatment of various cranial diseases, on the viability of neurons. Materials and Methods:Neuronal cell culture was prepared from the frontal cortex of 9 newborn rats. Cultured cells were irradiated with gamma-ray for 1-10 min by 152 Eu, 241 Am, and 132 Ba isotopes, visible light for 1-160 min, and laser light for 0.2-2 seconds. The MTT tetrazolium reduction assay was used to assess the number of viable cells in the neuronal cell cultures. Wavelength dispersive X-ray fluorescence spectrometer was used to determine Na, K, and Ca levels in cellular fluid obtained from neuronal cell culture plaques. Ba isotopes, cell viability insignificantly decreased with time (p>0.05). On the other hand, exposure to visible light produced statistically significant decrease in cell viability at both short-(1-10 min) and long-term (20-160 min). Cell viability did not change with 2 seconds of laser exposure. Na, K, and Ca levels significantly decreased with gamma-ray and visible light. The level of oxidative stress markers significantly changed with gamma-ray. Results Conclusion:In conclusion, while low dose gamma-ray has slight to moderate apoptotic effect in neuronal cell cultures by oxidative stress, long-term visible light induces remarkable apoptosis and cell death. Laser light has no significant effect on neurons. Further genetic studies are needed to clarify the chronic effect of visible light on neuronal development and functions.Keywords: Neuron, cytotoxicity, cell culture, apoptosis, laser light, radiation Öz Amaç: Amacımız, çeşitli kranial hastalıkların tedavisi esnasında nöronların sıklıkla maruz kaldığı gama ışını, laser ışığı ve görünür ışığın etkilerinin değerlendirilmesidir. Ba izotoplar ile düşük dozda radyasyon altında, istatiksel olarak anlamsız bir, zamanla azaldı. Öte yandan, görünür ışığa maruziyet hücre canlılığında hem kısa süreli (1-10 dk) hem de uzun süreli (20-160 dk) maruziyette anlamlı derecede düşüşe sebep olur. Hücre canlılığı lazere 2 saniye maruz kalma ile değişmedi. Na, K ve Ca seviyeleri gama ışını ve görünür ışık maruziyeti ile önemli ölçüde azalmıştır. Oksidatif stres belirteçleri seviyesi gama-ışını ile önemli ölçüde değişti. Gereç veSonuç: Düşük doz gama ışını oksidatif strese bağlı nöronal hücre kültürlerindeki apoptotik etkisi hafif ve orta düzeydeyken, uzun sü-reli görünür ışık dikkate değer bir apoptoz ve hücre ölümüne neden oldu. Lazer ışığı nöronlar üzerinde önemli bir etkiye sahip değildir. Görünür ışığın nöron gelişimi ve işlevleri üzerinde kronik etkisini açıklamak için ileri genetik çalışmalar yapılmasına ihtiyaç vardır.

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Induction of sister chromatid exchanges by UV light and its inhibition by caffeine

Cited by 173 publications

References 25 publications

Radiosensitivity in ataxia-telangiectasia: a new explanation.

Radiosensitivity in ataxia-telangiectasia: a new explanation.

Induction of chromosome shattering by ultraviolet irradiation and caffeine: comparison of whole cell and partial-cell irradiation

Once the Light Touch to the Brain: Cytotoxic Effects of Low-Dose Gamma-Ray, Laser Light, and Visible Light on Rat Neuronal Cell Culture

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