Long-term expression of transforming growth factor TGF beta 1 in mouse skin after localized beta-irradiation.

The long-term expression of TGF beta 1 in mouse skin after localized irradiation with a beta-emitting source is reported. The skin of CBA/ca mice was exposed to 50 Gy superficial beta radiation from an 11 mm strontium-90 source. Such a dose produced an acute moist desquamation reaction in 100% of the animals, which was macroscopically resolved within 30 days.

Expression of transforming growth factor-beta 1 in mouse skin during the acute phase of radiation damage.

Transforming growth factor-beta (TGF beta 1) plays a central role in wound healing, so its perturbation by radiation may contribute to the acute and late effects seen in irradiated skin. TGF beta 1 mRNA expression was measured by PCR, in the skin of the CD1 and CBA mouse, exposed to Sr-90 beta from an 11-mm diameter source. TGF beta 1 mRNA expression increased sharply after doses between 1 and 10 Gy and plateaued at approximately 200% above controls after doses between 20 and 50 Gy.

The effect of whole-body gamma-irradiation on localized beta-irradiation-induced skin reactions in mice.

The combined effects of whole-body radiation and localized radiation trauma have received scant experimental attention. However, in the recent accidents at Chernobyl and Goiania skin damage from beta-contamination was combined with total-body radiation and in many cases the skin lesions which covered large surfaces of the body were severe and recovery was prolonged. This paper models the immunosuppressive effects of whole-body gamma-radiation in the sublethal to lethal range (1-11 Gy) on the skin reactions produced by 50 Gy of superficial beta-radiation.

Differences in vascular response between primary and transplanted tumours.

The vast majority of studies on tumour vasculature are performed on transplanted tumours in rodents. However, it is known that there may be differences between primary and transplanted lesions. The purpose of this study is to test whether a specific vascular response is similar in primary tumours and in transplanted tumours derived from them.

Experimental studies of radiation carcinogenesis in the skin: a review.

Skin has been widely used in radiation carcinogenesis studies because of the accessibility and visibility of its tumours. Both rat and mouse models have proved to be sensitive, reproducible systems to study the dose and time response of cancer induction following different modes and qualities of radiation exposure. This paper discusses the variation in the shape of the low-LET dose responses from purely linear with no threshold to the highly quadratic curves with significant thresholds, although a linear response is more consistently reported following high-LET radiations.

Skin carcinogenesis following uniform and nonuniform beta irradiation.

In practical situations where workers or the general public may be exposed to ionizing radiation, the resulting irradiation is rarely uniform. The risk figures and dose limits recommended by the International Commission on Radiological Protection (ICRP) are based largely on clinical and epidemiological studies of reasonably uniform irradiated organs. The paucity of clinical or experimental data for highly nonuniform exposures has prevented the ICRP from providing adequate recommendations applicable to this practical situation.

Lung tumour induction in mice after X-rays and neutrons.

Dose-response curves were determined for pulmonary adenomas and adenocarcinomas in mice after single acute doses of 200 kVp X-rays and cyclotron neutrons (E = 7.5 MeV). A serial-killing experiment established that the radiation induces the tumours and does not merely accelerate the appearance of spontanoeus cancers [corrected].

The radiosensitivity of embryos of domestic chickens and black-headed gulls.

Eggs of domestic chickens and black-headed gulls were continuously exposed to gamma-rays during incubation, using dose rates ranging from 0.004 to 0.08 Gy h-1 for 20 days.

Proliferation of type II pneumonocytes after X-irradiation.

This paper reports preliminary data on the proliferative response of type II cells in the mouse lung over a five-month period after external thoracic doses of 2, 5, 10 and 12 Gy of X-rays. The DNA labelling index (LI) of control (0 Gy) mice was at all times exceedingly low (0.3-0.

Radiation effects in the lung.

This article outlines the principles of radiobiology that can explain the time of onset, duration, and severity of the complex reactions of the lung to ionizing radiation. These reactions have been assayed biochemically, cell kinetically, physiologically, and pathologically. Clinical and experimental data are used to describe the acute and late reactions of the lung to both external and internal radiation including pneumonitis, fibrosis and carcinogenesis.

Lung tumour induction in mice after uniform and non-uniform external thoracic X-irradiation.

The aim of this study was to investigate the validity of the ICRP procedure of using average tissue/organ dose in estimating carcinogenic risk. It has been suggested that highly non-uniform exposure ('hot spots') is much more carcinogenic than an equivalent dose delivered uniformly. In a series of experiments, mice were irradiated with X-rays either uniformly to the thorax or non-uniformly with 72 1-mm microbeams which irradiated approximately 20 per cent of the total lung volume.

The influence of the hair cycle on the thickness of mouse skin.

The data on mouse skin thickness reported here was prompted by the need to know the true position of basal cells of the epidermis and hair follicles as these are important "cells at risk" for a variety of skin reactions including carcinogenesis following exposure to radiation. There is little reliable data in the literature and most previous reports have ignored the shrinkage of skin that occurs because of its natural elasticity. The values determined for mouse flank skin in telogen--the resting phase of the hair cycle for the different skin layers--are epidermis 10 micron, corium 250 micron, adipose layer 150 micron, and hair follicle depth 150 micron.

Changes in the DNA labelling index after beta irradiation of the mouse epidermis.

This study looked at the changes in the interfollicular DNA labelling index (LI) with time after strontium-90/yttrium-90 beta irradiation of approximately 100 mm2 of mouse flank skin, after a dose of 100 Gy which produces transitory moist desquamation. Within 24 hr of such a dose the LI of the irradiated area was essentially zero (0.07 +/- 0.

Nonstochastic effects of different energy beta emitters on the mouse skin.

The effect of irradiating varying areas of mouse skin from 860 down to 0.8 mm2 with different energy beta emitters was studied to clarify protection problems of localized doses to the skin. Both 90Sr and 170Tm sources show area effects for dose-response curves.

The proliferation kinetics of pulmonary alveolar macrophages.

In this study the proliferation kinetics of pulmonary alveolar macrophages (PAMs) are determined using [3H]thymidine labeling, flow cytofluorimetry, metaphase arrest, and the percentage of labeled mitoses. The demonstration of in situ PAM proliferation is demonstrated beyond doubt. Comparison of the turnover time, calculated from cell kinetic parameters, with the experimentally determined migration times shows that the contribution proliferating PAMs make to their own population size is significant.

Evidence for the pulmonary origin of alveolar macrophages.

This paper supports the hypothesis that some form of pulmonary alveolar macrophage (PAM) production occurs within the lung in the normal steady state. The study involved monitoring the change in number of labelled PAMs following two modes of irradiation--the first with the thorax being irradiated and the rest of the mouse shielded, the second with the thorax shielded and the body irradiated. Also measurements of monocyte and PAM numbers after a single bone marrow irradiation were carried out.

Cell kinetics of pulmonary alveolar macrophages in the mouse.

The study of pulmonary alveolar macrophages (PAMs) involves two techniques, one following the migration of a cohort of labelled PAMs from the lung and the other involves the use of a continuous labelling method with [3H]TdR. In both studies, strikingly similar, probably biphasic curves are obtained that can be interpreted as indicating the existence of two proliferating cell populations with turnover times of approximately 10 days and approximately 35 days. It is suggested that one of these compartments is an intra-alveolar PAM population whilst the other probably represents a precursor population.

The effects of negative pions on spermatogonial survival in the mouse.

A study of the radiation effects of pi-mesons on the testes of the mouse has been carried out using the pion beam at the SRC Rutherford Laboratory. The cell killing effects on type B and intermediate spermatogonia have been assessed and compared with the effects of 20-0 kVp X rays, delivered at the same dose rate. It was found that not only did irradiation of the testes not disturb the kinetics of spermatogenesis, but also the RBE for pions measured in the Bragg peak and on the plateau was not significantly different from unity.