The effect of HIV and antiretroviral therapy on chromosomal radiosensitivity

Introduction: Antiretroviral Treatment (ART) has led to an improvement in survival of HIV infected individuals. Some of them will develop cancer during the course of their infection and will require radiation therapy. HIV positive cancer patients have presented with adverse side effects of radiotherapy and elevated chromosomal radiosensitivity. This study investigated if ART has an influence on chromosomal radiosensitivity of HIV positive individuals. Methods and Materials: Blood samples from 60 HIV positive individuals were in vitro exposed to doses of X-rays of 0, 2 and 4Gy and chromosomal radiosensitivity was assessed with the micronucleus assay. The micronucleus assay was also performed on lymphocytes of a group of non HIV-infected health care workers taking prophylactic post-exposure ART to measure the effect of these ART drugs on chromosomal radiosensitivity without HIV as a confounding factor. Results: All HIV patients (those on ART and without ART) had significantly higher radiation induced Micronuclei (MN) than healthy controls. The MN yields increased in the HIV patients taking ART compared to HIV patients not on treatment. The evaluation of chromosomal radiosensitivity of health care workers on ART revealed no effects of ART. Conclusions: HIV positive individuals show an increased chromosomal radiosensitivity. Antiretroviral treatment given to HIV positive individuals can lead to enhanced chromosomal radiosensitivity and therefore impose higher risks for radiotherapy side effects in these patients

Fluorescence in situ hybridisation study of micronuclei in C3A cells following exposure to ELF-magnetic fields

Human C3A cells were exposed to extremely low frequency (50 Hz) magnetic fields (ELF-MF's) up to 500 mu T. They were subjected to the micronucleus assay using a Fluorescence In Situ Hybridization (FISH) technique with an in-house pan-centromere probe. We found no increased frequency in micronucleated cells and no change in the proportion of centromere positive over centromere negative micronuclei compared to the unexposed control cells. These results are in accordance with some, but in contradiction with other previously published investigations underlining that effects of environmental ELF-EMF's on cellular DNA may be very subtle and that small changes or environmental influences may determine the outcome of a (geno)toxicity study. Interestingly, a low-level (5 mu T) exposure resulted in less than the background micronucleus frequency

Potentiation of the abscopal effect by modulated electro-hyperthermia in locally advanced cervical cancer patients

Background: A Phase III randomized controlled trial investigating the addition of modulated electro-hyperthermia (mEHT) to chemoradiotherapy for locally advanced cervical cancer patients is being conducted in South Africa (Human Research Ethics Committee approval: M1704133; ID: NCT03332069). Two hundred and ten participants were randomized and 202 participants were eligible for six month local disease control evaluation. Screening F-18-FDG PET/CT scans were conducted and repeated at six months post-treatment. Significant improvement in local control was reported in the mEHT group and complete metabolic resolution (CMR) of extra-pelvic disease was noted in some participants. We report on an analysis of the participants with CMR of disease inside and outside the radiation field. Method: Participants were included in this analysis if nodes outside the treatment field (FDG-uptake SUV>2.5) were visualized on pre-treatment scans and if participants were evaluated by F-18-FDG PET/CT scans at six months post-treatment. Results: One hundred and eight participants (mEHT: HIV-positive n = 25, HIV-negative n = 29; Control Group: HIV-positive n = 26, HIV-negative n = 28) were eligible for analysis. There was a higher CMR of all disease inside and outside the radiation field in the mEHT Group: n = 13 [24.1%] than the control group: n = 3 [5.6%] (Chi squared, Fisher's exact: p = 0.013) with no significant difference in the extra-pelvic response to treatment between the HIV-positive and -negative participants of each group. Conclusion: The CMR of disease outside the radiation field at six months post-treatment provides evidence of an abscopal effect which was significantly associated with the addition of mEHT to treatment protocols. This finding is important as the combined synergistic use of radiotherapy with mEHT could broaden the scope of radiotherapy to include systemic disease

The cytokinesis-block micronucleus assay on human isolated fresh and cryopreserved peripheral blood mononuclear cells

The cytokinesis-block micronucleus (CBMN) assay is a standardized method used for genotoxicity studies. Conventional whole blood cultures (WBC) are often used for this assay, although the assay can also be performed on isolated peripheral blood mononuclear cell (PBMC) cultures. However, the standardization of a protocol for the PBMC CBMN assay has not been investigated extensively. The aim of this study was to optimize a reliable CBMN assay protocol for fresh and cryopreserved peripheral blood mononuclear cells (PBMCS), and to compare micronuclei (MNi) results between WBC and PBMC cultures. The G(0)CBMN assay was performed on whole blood, freshly isolated, and cryopreserved PBMCS from healthy human blood samples and five radiosensitive patient samples. Cells were exposed to 220 kV X-ray in vitro doses ranging from 0.5 to 2 Gy. The optimized PBMC CBMN assay showed adequate repeatability and small inter-individual variability. MNi values were significantly higher for WBC than for fresh PBMCS. Additionally, cryopreservation of PBMCS resulted in a significant increase of MNi values, while different cryopreservation times had no significant impact. In conclusion, our standardized CBMN assay on fresh and cryopreserved PBMCS can be used for genotoxicity studies, biological dosimetry, and radiosensitivity assessment

Defining characteristics of nodal disease on PET/CT scans in patients with HIV-positive and -negative locally advanced cervical cancer in South Africa

Literature reports increased FDG nodal uptake in HIV-positive patients. Our aim is to identify differences in presentation and characteristics of FDG-avid lymph nodes between HIV-positive and HIV-negative locally advanced cervical cancer (LACC) patients in our clinical setting. We evaluated 250 pre-treatment F-18-FDG PET/CT imaging studies from women screened for a phase III randomised controlled trial investigating modulated electro-hyperthermia as a radiosensitiser (Ethics approval: M120477). The number of nodes; size; maximum standardised uptake value (SUVmax); symmetry; and relationship between nodal size and SUVmax uptake, were assessed by region and by HIV status. In total, 1314 nodes with a SUVmax >= 2.5 were visualised. Of 128(51%) HIV-positive participants, 82% were on antiretroviral therapy (ART) and 10 had a CD4 count four nodes visualised in the neck, symmetrical inguinal lymph nodes, increased rates of supraclavicular node visualisation; FDG-avid axillary nodes were more common, but not exclusive, in HIV-positive participants. F-18-FDG PET/CT is a reliable staging method for LACC in HIV-positive patients who are not in acute stages of HIV infection, have a CD4 count >200 cells/mL, and/or are on ART and there is a potential risk of underestimating metastatic spread by attributing increased nodal metabolic activity to HIV infection in these patients