Modification of radiation-induced chromosome damage and micronucleus induction in mouse bone marrow by misonidazole and hyperthermia

Protective Effects of Hydrogen against Low-Dose Long-Term Radiation-Induced Damage to the Behavioral Performances, Hematopoietic System, Genital System, and Splenic Lymphocytes in Mice

Molecular hydrogen (H₂) has been previously reported playing an important role in ameliorating damage caused by acute radiation. In this study, we investigated the effects of H₂ on the alterations induced by low-dose long-term radiation (LDLTR). All the mice in hydrogen-treated or radiation-only groups received 0.1 Gy, 0.5 Gy, 1.0 Gy, and 2.0 Gy whole-body gamma radiation, respectively. After the last time of radiation exposure, all the mice were employed for the determination of the body mass (BM) observation, forced swim test (FST), the open field test (OFT), the chromosome aberration (CA), the peripheral blood cells parameters analysis, the sperm abnormality (SA), the lymphocyte transformation test (LTT), and the histopathological studies. And significant differences between the treatment group and the radiation-only groups were observed, showing that H₂ could diminish the detriment induced by LDLTR and suggesting the protective efficacy of H₂ in multiple systems in mice against LDLTR.

Hyperthermia-induced micronucleus formation in a human keratinocyte cell line

Elevated temperature can cause biological effects in vitro and in vivo. Many studies on effects of hypo- and hyperthermia have been conducted, but only few studies systematically investigated the formation of genomic damage in the micronucleus test in human cells in vitro as a consequence of different temperatures. In the present study, HaCaT human keratinocytes were exposed to different temperatures from 37°C to 42°C for 24h in a regular cell culture incubator. Micronucleus frequency as a marker of genomic damage was elevated in a temperature-dependent and statistically significant manner. Apoptosis occurred at temperatures of 39°C or higher. Cell proliferation was unaffected up to 40°C and decreased at 41°C and 42°C. Expression of the heat shock protein Hsp70 was elevated, particularly at temperatures of 40°C and higher. These findings are in agreement with several in vivo studies and some in vitro studies looking at single, specific temperatures, but a systematically investigated temperature-dependent increase of genomic damage in human keratinocytes in vitro is demonstrated for the first time here.

Influence of neoadjuvant radiochemotherapy combined with hyperthermia on the quality of life in rectum cancer patients

PURPOSE

The present study compares quality of life (QoL) after neoadjuvant radiochemotherapy with or without hyperthermia in patients with advanced rectal cancer.

METHODS

Between April 1994 and May 1999, 137 patients were treated by neoadjuvant radiochemotherapy with (69 patients (50.4%)) or without (68 patients (49.6%)) hyperthermia. Forty-six patients (33.6%) filled-out a 'Gastrointestinal Quality of Life Index' (GIQLI) questionnaire at four time points (before and after neoadjuvant therapy, early after surgery and after long-term follow-up) and were included in the present study.

RESULTS

There were no statistically significant differences in the global GIQLI index between patients treated with neoadjuvant radiochemotherapy with and without hyperthermia at any time point. The longitudinal analysis of GIQLI values in both treatment groups showed specific profiles that were identical in both treatment groups. Occurrence of severe toxicity during the neoadjuvant therapy in both arms lead to a significant temporary reduction of QoL scores at TP2 without any detrimental long-term effects. Patients with sphincter preservation and patients with sphincter resection reported similar QoL scores during long-term follow-up.

CONCLUSION

Neoadjuvant radiochemotherapy with and without hyperthermia has similar effects on the QoL of patients with locally advanced rectal cancer. The addition of hyperthermia during the neoadjuvant therapy with the potentially associated inconveniences has no negative effects on QoL.

Hyperthermia for rectal cancer

BACKGROUND

In order to improve the clinical results of rectal cancer, hyperthermia has been prescribed in combination with chemotherapy and radiotherapy. The techniques of hyperthermia and their clinical applications to rectal cancer were reviewed.

METHODS

The development of heating devices has been intensively investigated, including external heating devices, intraluminal heating devices, circulation of warmed saline solution, and whole body hyperthermia.

RESULTS

Nonrandomized and randomized trials for rectal cancer have demonstrated an improved local response with the combined use of hyperthermia and conventional treatments. A preoperative therapy with hyperthermia increased resectability and decreased local recurrence, resulting in the improvement of the postoperative prognosis. There were no major postoperative complications related to the preoperative treatment. A lower incidence of local recurrence was observed in groups that underwent intra- or postoperative hyperthermia treatment, as compared with control groups. In cases with unresectable or local recurrent rectal cancer, hyperthermia achieved a local tumor regression and prolonged pain relief.

CONCLUSIONS

These clinical data suggest that hyperthermia combined with radiation or chemotherapy demonstrates great promise for the treatment of patients with carcinoma of the rectum.

Analysis of histological therapeutic effect, apoptosis rate and p53 status after combined treatment with radiation, hyperthermia and 5-fluorouracil suppositories for advanced rectal cancers

The tumour-suppressor gene p53 encodes a transcription factor that plays a critical role in the induction of G1 cell cycle arrest and apoptosis after DNA damage. To clarify the role of the p53 gene and apoptosis in combined hyperthermia, chemotherapy and radiation (hyperthermochemoradiotherapy, HCR therapy) for rectal cancer, we examined the histological response, rate of apoptosis, DNA fragmentation and p53 status in tumours from 28 patients undergoing HCR therapy before surgery and from 22 patients who did not have preoperative treatment. The therapeutic effect of HCR therapy was closely correlated with the rate of apoptosis; the correlation was statistically significant, suggesting that this effect occurs through apoptosis. The incidence of p53 mutations in the treated group were as follows: in tumours resistant to HCR therapy, four of seven (57.1%); intermediately sensitive, 7 of 13 (53.9%); or sensitive, three of eight (37.5%), suggesting that the therapeutic effect and apoptosis rate were related to the p53 status of the tumours to some extent, but the relation was not statistically significant. In the 22 control tumours (non-treated group), the apoptosis rate was 2.0 +/- 1.1%, and there was no significant difference in p53 status compared with the HCR group. Our study indicates that the pathological response to HCR therapy correlates with the rate of apoptosis with statistical significance and that it induces the therapeutic effect more significantly in rectal cancer cells with wild-type p53, although HCR therapy-induced apoptosis also occurs in some rectal cancers with mutated p53. Therefore, this combination therapy can induce an additive or synergistic anti-tumour effect in rectal cancers with wild-type p53 as well as in those with mutated p53 through apoptosis, offering new therapeutic opportunities and a better prognosis.

Protection against radiation-induced chromosome damage in mouse bone marrow by Ocimum sanctum

The radioprotective effect of the leaf extract of Ocimum sanctum (Ocimum extract, OE) was investigated by taking chromosome aberrations as the end point. Adult Swiss mice were whole-body exposed to 1-6 Gy of gamma radiation with/without pretreatment with 10 mg/kg b.wt. of OE intraperitoneally for 5 consecutive days. Radiation was given 30 min after the last injection. Metaphase plates were prepared from femur marrow on days 1, 2, 7 and 14 post-treatment and the frequency of aberrant cells and individual aberrations were scored. OE alone did not have any significant effect on the chromosomes. Maximum percent of aberrant cells was observed at 24 h in all the exposed groups. The percent aberrant cells showed a linear quadratic increase with radiation dose, in both radiation alone (RT) and OE + RT-treated groups. Exchange (dicentrics and rings) and multiple (pulverized and severely damaged cells) aberrations also showed a similar response. However, the slopes of OE + RT was significantly shallower than RT groups (p < 0.05). A dose-modifying factor of 2.63 was obtained taking percent aberrant cells for 2 Gy as the base. Progressive decline in the percent aberrant cells as well as the number of aberrations with time after irradiation was observed in both RT and OE + RT groups. OE treatment resulted in a faster recovery compared to RT alone group. At doses below 3 Gy, OE pretreatment almost completely eliminated the exchange aberrations from the cell population by day 2. Studies on a chemical system demonstrated that OE significantly reduced the generation of hydroxyl radical; a lower dose of OE (1 mg/ml) was more effective than 5 mg/ml and this effect was more pronounced than that produced by DMSO. These results show that OE affords in vivo protection against radiation-induced cytogenetic damage. Free radical scavenging is a likely mechanism of OE protection.