Cleaved caspase-3 is present in the majority of glial cells in the intact rat spinal cord during postnatal life.

Cell death is an essential process that occurs during the development of the central nervous system. Despite the availability of a wide range of commercially produced antibodies against various apoptotic markers, data regarding apoptosis in intact spinal cord during postnatal development and adulthood are mostly missing. We investigated apoptosis in rat spinal cord at different stages of ontogenesis (postnatal days 8, 29, and 90). For this purpose, we applied immunofluorescent detection of two widely used apoptotic markers, cleaved caspase-3 (cC3) and cleaved poly(ADP-ribose) polymerase (cPARP). Surprisingly, we found significant discrepancy between the number of cC3+ cells and PARP+ cells, with a ratio between 500:1 and 5000:1 in rat spinal cord at all postnatal time points. The majority of cC3+ cells were glial cells and did not exhibit an apoptotic phenotype. In contrast with in vivo results, in vitro analysis of primary cell cultures derived from neonatal rat spinal cord and treated with the apoptotic inductor staurosporine revealed a similar onset of occurrence of both cC3 and cPARP in cells subjected to apoptosis. Gene expression analysis of spinal cord revealed elevated expression of the Birc4 (XIAP), Birc2, and Birc5 (Survivin) genes, which are known potent inhibitors of apoptosis. Our data indicate that cC3 is not an exclusive marker of apoptosis, especially in glial cells, owing its possible presence in inhibited forms and/or its participation in other non-apoptotic roles. Therefore, cPARP appears to be a more appropriate marker to detect apoptosis.

Flow cytometric method for estimation of 5-bromo-2´-deoxyuridine content in rat serum.

Labelling of DNA in replicating cells using 5-bromo-2´-deoxyuridine (BrdU) is widely used, however the rapid clearance and metabolisation of BrdU in the living organism is a critical issue. Although the pharmacokinetic of BrdU in experimental animals is empirically approximated, the exact time-curve remains unknown. Here we present novel method for estimation of the BrdU content in the blood serum. The application is based on the in vitro cocultivation of tumour cells with the examined serum and the subsequent quantification of the incorporated BrdU in the DNA using flow cytometry analysis. Our results demonstrate that this approach can quantify the BrdU concentration in serum at 1 micromol.dm(-3) and might represent an attractive alternative to conventional chromatographic analysis. The employment of tumour cells as "detectors" of the BrdU content in serum provides an advantage over high pressure liquid chromatography (HPLC), as this approach allows us to approximate not only the concentration of BrdU, but also to determine, whether BrdU is present in the blood serum in effective concentration to reliable label all cells undergoing the S-phase of the cell cycle. The presented application might be a helpful tool for studies on pharmacokinetics of BrdU or other thymidine analogues when testing various administration routes or protocols.

Effects of prenatal irradiation on behaviour and hippocampal neurogenesis in adult rats.

Prenatal irradiation is known to have aversive effects on the brain development, manifested in changes in some behavioural parameters in adult individuals. The aim of our work was to assess the effect of prenatal irradiation on different forms of behaviour and on hippocampal neurogenesis in rats. Pregnant female rats were irradiated with a dose of 1 Gy of gamma rays on the 16th day of gravidity. The progeny of irradiated and control animals aged 3 months were tested in Morris water maze (MWM), open field (OF) and in elevated plus maze test (PM). The prenatal irradiation negatively influenced the short-term spatial memory in MWM in female rats, although the long-term memory was not impaired. A statistically significant increase of basic locomotor activity in OF was observed in irradiated rats. The comfort behaviour was not altered. The results of PM showed an increase of anxiety in irradiated females. The level of hippocampal neurogenesis, assessed as the number of cells labelled with 5-bromo-2-deoxyuridine in the area of gyrus dentatus, was not statistically different in irradiated rats. Our results indicate, that prenatal irradiation with a low dose of gamma-rays can affect some innate and learned forms of behaviour in adult rats. We did not confirm a relation of behavioural changes to the changes of hippocampal neurogenesis.

A survey of the Czechoslovak follow-up of lung cancer mortality in uranium miners.

The major Czechoslovak cohort of uranium miners (S-cohort) is surveyed in terms of diagrams illustrating dependences on calendar year, age, and exposure to radon and radon progeny. An analysis of the dose dependence of lung cancer mortality is performed by nonparametric and, subsequently, by parametric methods. In the first step, two-dimensional isotonic regression is employed to derive the lung cancer mortality rate and the relative excess risk as functions of age attained and of lagged cumulated exposure. In a second step, analytical fits in terms of relative risk models are derived. The treatment is largely analogous to the methods applied by the BEIR IV Committee to other major cohorts of uranium miners. There is a marked dependence of the excess risk on age attained and on time since exposure. A specific characteristic of the Czechoslovak data is the nonlinearity of the dependence of the lung cancer excess risk on the cumulated exposure; exposures on the order of 100 working level months or less appear to be more effective per working level month than larger exposures but, in the absence of an internal control group, this cannot be excluded to be due to confounders such as smoking or environmental exposures. A further notable observation is the association of larger excess risks with longer protraction of the exposures.

Cancer in man after exposure to Rn daughters.

Results are reported of epidemiological studies in six groups of miners, who work in U mines, Fe mines and shale clay mines. A significant excess of lung cancer was proved in exposure categories below 50 WLM, the first significant excess of lung cancer rate was found in the sixth year following the start of exposure, and a significant difference between the observed and expected rate was found in miners even before the fortieth year of age. The mean attributable annual cancer risk after about 30 y of observation in the whole study was approximately 20.0 and in persons starting exposure after 30 y of age the risk was approximately 30.0 per year per 1 WLM per 10(6) persons. The dose-effect relationship and the attributable lung cancer risk per 1 WLM were significantly influenced by the age at the first exposure by total accumulated exposure and by the character of the accumulation of exposure. The observed effects of smoking and exposure to alpha radiation from Rn daughters were nearly additive. The lung cancer risk per 1 WLM at low levels of exposure (not including the contribution from natural sources in the living environment) in U as well as Fe mines indicated a certain elevation compared with the risk at higher accumulated exposure.

Histologic types of bronchogenic cancer in relation to different conditions of radiation exposure.

The rish of lung cancer among the uranium miner study group was found to be not only connected with the increase in frequency of different histologic types of lung cancer, but mainly with the increase of small cell undifferentiated and epidermoid type frequencies. It appears that the frequency of these two major histologic types may be influenced by the level of cumulated radiation exposure and by the time course of cumulation of exposure in a different way. These findings, in agreement wit recent data of Archer et al., eliminate the former assumption that radiation can induce an elevated frequency of only one histologic type of lung cancer.