In dry etching processes--one of the sources of potential exposure to toxic wastes in the semiconductor industry--complex mixtures of inorganic and organic compounds arise from reactions between feed stock gases (BCl3/Cl2), top layers (aluminium photoresist), and the carrier gas (N2). Two different fractions of the complex mixture--one an ethanolic solution (ES) and the other an insoluble liquid residue (LR)--were examined for acute oral toxicity in rats. Analytical data showed that the ethanol soluble fraction contained mainly inorganic compounds, whereas the residue contained various halogenated hydrocarbons. Neither death nor behavioral changes occurred after oral administration and observation up to 23 days. ES caused a lower mean arterial blood pressure in both sexes, increased P-R-intervals in male rats, and caused some mild biochemical and hematological alterations and changes in relative organ weights compared to the control groups. Exposure to LR influenced food and water intake, and caused a significant decrease in body weights, signs of polyurie, as well as changes in various relative organ weights and biochemical and hematological parameters. The blood pressure of the male animals fell and the heart rates of both sexes decreased.

Aluminum↗

PubMedDate not supplied

Radiosensitization in sarcoma cell lines with a p53 missense mutation correlates with prevention of irradiation G2/M arrest but not with induction of apoptosis.

We analysed the effects of caffeine and taxol on the radiobiological behaviour of two human sarcoma cell lines (RD, SK-LMS-1) each with a p53 missense mutation. Treatment with 2 mM caffeine resulted in an inhibition of the irradiation induced G2/M arrest in both cell lines. This effect was coupled with a radiosensitization in cell line SK-LMS-1 after an irradiation with 6 Gy (enhancement factor of 5.0). However, the effect of radiosensitization was not correlated with an induction of apoptosis. Incubation with 20 nM taxol increased the irradiation induced apoptosis almost 3-fold in cell line SK-LMS-1, but not in cell line RD. However, taxol had no effect on the irradiation induced G2/M arrest or radiosensitivity in either cell line. The results support the hypothesis that the prevention of irradiation induced G2/M arrest but not the induction of apoptosis plays a critical role in determining radiosensitivity in sarcoma cell lines with p53 mutations.

Apoptosis↗

PubMedDate not supplied

G2/M checkpoint is p53-dependent and independent after irradiation in five human sarcoma cell lines.

To determine the role of p53 in G2/M arrest, G2/M transition and apoptosis, we investigated five human sarcoma cell lines with different p53 gene status in their response to X-rays. The p53 status of the cell lines was mutant (US 8-93, LMS 6-93 and RD), null (SAOS-2) and wildtype (A-204). Clonogenic survival of the cell lines varied as the survival fraction at 2 Gy (SF2) ranged from 0.28 to 0.79. Compared with the mutated p53 cell lines (SF2 with a range from 0.46 to 0.79) the clonogenic survival of the wildtype p53 (wt-p53) cell line A-204 (SF2 = 0.34) was lower. The p53 null cell line (SAOS-2) was also sensitive to X-rays (SF2 = 0.28). We detected, in all cell lines a similar behavior in their response to irradiation with G2/M arrest and apoptosis. However, the maximal rate of apoptosis with a range from 7.0 to 18.0% was rather small. The decrease of G2/M cells was coupled with an increased percentage of apoptotic cells. However, a different delay in G2/M did not result in a change of radiation sensitivity. Western analyses showed an increased P53 level only for the cell line A-204 (wt-p53) after irradiation. Our results point out that there is not always a simple relationship between p53 gene status and radiation sensitivity. We suggest, that wt-p53 plays an active role in G2/M arrest and in decreasing the number of G2/M cells as a response to apoptosis. Therefore, p53-dependent regulation in G2/M may be as important as p53-independent mechanisms.

Apoptosis↗