Nicotinamide as a repair inhibitor in vivo: studies using single and fractionated X-ray doses in mouse skin and kidneys
Rojas, A ; Denekamp, J ; Johns, H ; Kjellén, Elisabeth LU ; Tsang, R ; Nilsson, Per LU
; Stratford, M R
; Dennis, M F
and Joiner, M C
(1996)
In Radiation Research
145(4).
p.419-431
- Abstract
- Inhibitors of adenosine diphosphoribosyl transferase, like nicotinamide, 3-aminobenzamide and other analogues, can inhibit repair of radiation-induced sublethal and/or potentially lethal damage in some in vitro systems. Therefore, we have tested the effect of nicotinamide on repair parameters in vivo in two rodent normal tissues. In skin, the sensitivity to dose fractionation (1, 2, 5 or 10 X-ray fractions in 5 days) was monitored by defining the alpha/beta ratio in the presence or absence of nicotinamide (0.5 mg g-1) in air or carbogen. Pre- and postirradiation sensitization were investigated using an X-ray schedule of 5 fractions/5 days in carbogen alone or combined with nicotinamide given 1 h before, immediately after or 8 h after... (More)
- Inhibitors of adenosine diphosphoribosyl transferase, like nicotinamide, 3-aminobenzamide and other analogues, can inhibit repair of radiation-induced sublethal and/or potentially lethal damage in some in vitro systems. Therefore, we have tested the effect of nicotinamide on repair parameters in vivo in two rodent normal tissues. In skin, the sensitivity to dose fractionation (1, 2, 5 or 10 X-ray fractions in 5 days) was monitored by defining the alpha/beta ratio in the presence or absence of nicotinamide (0.5 mg g-1) in air or carbogen. Pre- and postirradiation sensitization were investigated using an X-ray schedule of 5 fractions/5 days in carbogen alone or combined with nicotinamide given 1 h before, immediately after or 8 h after irradiation. Also, changes in the steepness of the underlying X-ray survival curve for the target skin clonogens, reflected by a change in the alpha/beta ratio, were investigated using the neutron top-up design. Underlying survival curves for oxygen +/- nicotinamide were obtained over the X-ray dose range 2.5 to 25 Gy, by administering single X-ray doses and following these with single top-up doses of d(4)-Be neutrons. Finally, in mouse kidney, recovery half-times (t1/2) were obtained by determining the time-dependent disappearance of X-ray damage using a split-dose design of two 6-Gy fractions separated by an interval which varied from 0 to 48 h and followed by two top-up doses from a neutron beam. No increase in alpha/beta for epidermal damage was seen with nicotinamide alone and, although sensitization was observed when the drug was given 1 h before irradiation, no postirradiation sensitization was detected. In kidney, there was no significant difference in the proportion of total repairable damage or in the half-life of recovery between treatments given with or without nicotinamide. Therefore, no decrease in normal tissue tolerance should be observed with the use of nicotinamide in clinical radiotherapy resulting either from reduced sparing with dose fractionation or from an increase in residual damage when shortening the interfraction interval. Finally, unless repair of radiation damage in normal tissues in vivo differs markedly from that of tumors, it is unlikely that the large sensitization seen in rodent tumors at 1.5 to 2 Gy per fraction, with carbogen and nicotinamide, can be attributed to nicotinamide acting as a repair inhibitor. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/1110160
- author
- Rojas, A
; Denekamp, J
; Johns, H
; Kjellén, Elisabeth
LU
; Tsang, R
; Nilsson, Per
LU
; Stratford, M R
; Dennis, M F
and Joiner, M C
- organization
- publishing date
- 1996
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Radiation Research
- volume
- 145
- issue
- 4
- pages
- 419 - 431
- publisher
- Radiation Research Society
- external identifiers
-
- pmid:8600502
- scopus:0029932043
- ISSN
- 0033-7587
- language
- English
- LU publication?
- yes
- id
- 71e5c5a5-2653-4e0a-babc-a5032cad322a (old id 1110160)
- date added to LUP
- 2016-04-01 16:27:11
- date last changed
- 2022-01-28 19:50:26
@article{71e5c5a5-2653-4e0a-babc-a5032cad322a,
abstract = {{Inhibitors of adenosine diphosphoribosyl transferase, like nicotinamide, 3-aminobenzamide and other analogues, can inhibit repair of radiation-induced sublethal and/or potentially lethal damage in some in vitro systems. Therefore, we have tested the effect of nicotinamide on repair parameters in vivo in two rodent normal tissues. In skin, the sensitivity to dose fractionation (1, 2, 5 or 10 X-ray fractions in 5 days) was monitored by defining the alpha/beta ratio in the presence or absence of nicotinamide (0.5 mg g-1) in air or carbogen. Pre- and postirradiation sensitization were investigated using an X-ray schedule of 5 fractions/5 days in carbogen alone or combined with nicotinamide given 1 h before, immediately after or 8 h after irradiation. Also, changes in the steepness of the underlying X-ray survival curve for the target skin clonogens, reflected by a change in the alpha/beta ratio, were investigated using the neutron top-up design. Underlying survival curves for oxygen +/- nicotinamide were obtained over the X-ray dose range 2.5 to 25 Gy, by administering single X-ray doses and following these with single top-up doses of d(4)-Be neutrons. Finally, in mouse kidney, recovery half-times (t1/2) were obtained by determining the time-dependent disappearance of X-ray damage using a split-dose design of two 6-Gy fractions separated by an interval which varied from 0 to 48 h and followed by two top-up doses from a neutron beam. No increase in alpha/beta for epidermal damage was seen with nicotinamide alone and, although sensitization was observed when the drug was given 1 h before irradiation, no postirradiation sensitization was detected. In kidney, there was no significant difference in the proportion of total repairable damage or in the half-life of recovery between treatments given with or without nicotinamide. Therefore, no decrease in normal tissue tolerance should be observed with the use of nicotinamide in clinical radiotherapy resulting either from reduced sparing with dose fractionation or from an increase in residual damage when shortening the interfraction interval. Finally, unless repair of radiation damage in normal tissues in vivo differs markedly from that of tumors, it is unlikely that the large sensitization seen in rodent tumors at 1.5 to 2 Gy per fraction, with carbogen and nicotinamide, can be attributed to nicotinamide acting as a repair inhibitor.}},
author = {{Rojas, A and Denekamp, J and Johns, H and Kjellén, Elisabeth and Tsang, R and Nilsson, Per and Stratford, M R and Dennis, M F and Joiner, M C}},
issn = {{0033-7587}},
language = {{eng}},
number = {{4}},
pages = {{419--431}},
publisher = {{Radiation Research Society}},
series = {{Radiation Research}},
title = {{Nicotinamide as a repair inhibitor in vivo: studies using single and fractionated X-ray doses in mouse skin and kidneys}},
volume = {{145}},
year = {{1996}},
}