Paradoxical Radiosensitizing Effect of Carnosic Acid on B16F10 Metastatic Melanoma Cells: A New Treatment Strategy.

Carnosic acid (CA) is a phenolic diterpene characterized by its high antioxidant activity; it is used in industrial, cosmetic, and nutritional applications. We evaluated the radioprotective capacity of CA on cells directly exposed to X-rays and non-irradiated cells that received signals from X-ray treated cells (radiation induced bystander effect, RIBE). The genoprotective capacity was studied by in vivo and in vitro micronucleus assays. Radioprotective capacity was evaluated by clonogenic cell survival, MTT, apoptosis and intracellular glutathione assays comparing radiosensitive cells (human prostate epithelium, PNT2) with radioresistant cells (murine metastatic melanoma, B16F10). CA was found to exhibit a genoprotective capacity in cells exposed to radiation (p < 0.001) and in RIBE (p < 0.01). In PNT2 cells, considered as normal cells in our study, CA achieved 97% cell survival after exposure to 20 Gy of X-rays, eliminating 67% of radiation-induced cell death (p < 0.001), decreasing apoptosis (p < 0.001), and increasing the GSH/GSSH ratio (p < 0.01). However, the administration of CA to B16F10 cells decreased cell survival by 32%, increased cell death by 200% (p < 0.001) compared to irradiated cells, and increased cell death by 100% (p < 0.001) in RIBE bystander cells (p < 0.01). Furthermore, it increased apoptosis (p < 0.001) and decreased the GSH/GSSG ratio (p < 0.01), expressing a paradoxical radiosensitizing effect in these cells. Knowing the potential mechanisms of action of substances such as CA could help to create new applications that would protect healthy cells and exclusively damage neoplastic cells, thus presenting a new desirable strategy for cancer patients in need of radiotherapy.

National inventory of authorized diagnostic imaging equipment in Ghana: data as of September 2020.

Introduction: to address the challenge of inadequate and non-equitable distribution of diagnostic imaging equipment, countries are encouraged to evaluate the distribution of installed systems and undertake adequate monitoring to ensure equitability. Ghana´s medical imaging resources have been analyzed in this study and evaluated against the status in other countries. Methods: data on registered medical imaging equipment were retrieved from the database of the Nuclear Regulatory Authority and analyzed. The equipment/population ratio was mapped out graphically for the 16 regions of Ghana. Comparison of the equipment/population ratio was made with the situation in other countries. Results: six hundred and seventy-four diagnostic imaging equipment units from 266 medical imaging facilities (2.5 units/facility), comprising computed tomography (CT), general X-ray, dental X-ray, single-photon emission computed tomography (SPECT) gamma camera, fluoroscopy, mammography and magnetic resonance imaging (MRI) were surveyed nationally. None of the imaging systems measured above the Organization for Economic Co-operation and Development (OECD) average imaging units per million populations (u/mp). The overall equipment/population ratio estimated nationally was 21.4 u/mp. Majority of the imaging systems were general X-ray, installed in the Greater Accra and Ashanti regions. The regional estimates of equipment/population ratios were Greater Accra (49.6 u/mp), Ashanti (22.4 u/mp), Western (21.4 u/mp), Eastern (20.6 u/mp), Bono East (20.0 u/mp), Bono (19.2 u/mp), Volta (17.9 u/mp), Upper West (16.7 u/mp), Oti (12.5 u/mp), Central (11.9 u/mp), Northern (8.9 u/mp), Ahafo (8.9 u/mp), Upper East (6.9 u/mp), Western North (6.7 u/mp), Savannah (5.5 u/mp) and North-East (1.7 u/mp). Conclusion: medical imaging equipment shortfall exist across all imaging modalities in Ghana. A wide inter-regional disparity in the distribution of medical imaging equipment exists contrary to WHO´s recommendation for equitable distribution. A concerted national plan will be needed to address the disparity.

Radiation-Induced Bystander Effect: Loss of Radioprotective Capacity of Rosmarinic Acid In Vivo and In Vitro.

In radiation oncology, the modulation of the bystander effect is a target both for the destruction of tumor cells and to protect healthy cells. With this objective, we determine whether the radioprotective capacity of rosmarinic acid (RA) can affect the intensity of these effects. Genoprotective capacity was obtained by determining the micronuclei frequencies in in vivo and in vitro assays and the cell survival was determined by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay) (MTT) assay in three cell lines (PNT2, TRAMPC1 and B16F10), both in direct exposure to X-rays and after the production of radiation-induced bystander effect. The administration of RA in irradiated cells produced a decrease in the frequency of micronuclei both in vivo and in vitro, and an increase in cell survival, as expression of its radioprotective effect (p < 0.001) attributable to its ability to scavenge radio-induced free radicals (ROS). However, RA does not achieve any modification in the animals receiving serum or in the cultures treated with the irradiated medium, which expresses an absence of radioprotective capacity. The results suggest that ROS participates in the formation of signals in directly irradiated cells, but only certain subtypes of ROS, the cytotoxic products of lipid peroxidation, participate in the creation of lesions in recipient cells.

Genoprotective Effect of Some Flavonoids against Genotoxic Damage Induced by X-rays In Vivo: Relationship between Structure and Activity.

Flavonoids constitute a group of polyphenolic compounds characterized by a common gamma-benzo- pyrone structure considered in numerous biological systems to possess antioxidant capacity. Among the different applications of flavonoids, its genoprotective capacity against damage induced by ionizing radiation stands out, which has been related to antioxidant activity and its chemical structure. In this study, we determined the frequency of appearance of micronucleus in vivo by means of the micronucleus assay. This was conducted in mice treated with different flavonoids before and after exposure to 470 mGy X-rays; thereafter, their bone marrow polychromatophilic erythrocytes were evaluated to establish the structural factors enhancing the observed genoprotective effect. Our results in vivo show that the presence of a monomeric flavan-3-ol type structure, with absence of carbonyl group in position C4 of ring C, absence of conjugation between the carbons bearing the C2 = C3 double bond and the said ring, presence of a catechol group in ring B and characteristic hydroxylation in positions 5 and 7 of ring A are the structural characteristics that determine the highest degree of genoprotection. Additionally, a certain degree of polymerization of this flavonoid monomer, but maintaining significant levels of monomers and dimers, contributes to increasing the degree of genoprotection in the animals studied at both times of their administration (before and after exposure to X-rays).

Effect of Rosmarinic Acid and Ionizing Radiation on Glutathione in Melanoma B16F10 Cells: A Translational Opportunity.

To explain a paradoxical radiosensitizing effect of rosmarinic acid (RA) on the melanoma B16F10 cells, we analyzed the glutathione (GSH) intracellular production on this cell (traditionally considered radioresistant) in comparison with human prostate epithelial cells (PNT2) (considered to be radiosensitive). In PNT2 cells, the administration of RA increased the total GSH content during the first 3 h (p < 0.01) as well as increased the GSH/ oxidized glutathione (GSSG) ratio in all irradiated cultures during all periods studied (1h and 3h) (p < 0.001), portraying an increase in the radioprotective capacity. However, in B16F10 cells, administration of RA had no effect on the total intracellular GSH levels, decreasing the GSH/GSSG ratio (p < 0.01); in addition, it caused a significant reduction in the GSH/GSSG ratio in irradiated cells (p < 0.001), an expression of radioinduced cell damage. In B16F10 cells, the administration of RA possibly activates the metabolic pathway of eumelanin synthesis that would consume intracellular GSH, thereby reducing its possible use as a protector against oxidative stress. The administration of this type of substance during radiotherapy could potentially protect healthy cells for which RA is a powerful radioprotector, and at the same time, cause significant damage to melanoma cells for which it could act as a radiosensitive agent.

Radioprotective and Antimutagenic Effects of Pycnanthus angolensis Warb Seed Extract against Damage Induced by X Rays.

Although different studies have demonstrated different applications of Pycnanthus angolensis extracts in traditional African and Asian medicine, its possible antimutagenic or genoprotective capacities have never been explored. We studied these capabilities of Pycnanthus angolensis seed extract (PASE) by means of the two micronucleus assays, determining the frequency of micronucleus (MN) yield in mouse bone marrow (in vivo) and in human lymphocytes blocked by cytochalasin B (in vitro). PASE exhibited a significant genoprotective capacity (p < 0.001) against X-rays with a protection factor of 35% in both in vivo and in vitro assays. Further, its radioprotective effects were determined by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-tetrazolium bromide (MTT) cell viability test in two cell lines: one being radiosensitive (i.e., human prostate epithelium (PNT2) cells) and the other being radioresistant (i.e., B16F10 melanoma cells). In the radiosensitive cells, PASE showed a protection factor of 35.5%, thus eliminating 43.8% of X-ray-induced cell death (p < 0.001) and a dose reduction factor of 2.5. In the radioresistant cells, a protection factor of 29% (p < 0.001) with a dose reduction factor of 4 was realized. PASE elicited a greater radioprotective capacity than the substances currently used in radiation oncology and, thus, could be developed as a nutraceutical radioprotectant for workers and patients exposed to ionizing radiation.

Association between eNOS Gene Polymorphism (T786C and VNTR) and Sickle Cell Disease Patients in Ghana.

Endothelial nitric oxide synthase (eNOS) variants have been found to be associated with several vascular disorders as well as the pathogenesis of sickle cell disease (SCD) complications such as vaso-occlusive crises (VOC). Studies on eNOS gene variants among SCD patients are rare in Ghana and several other African countries. The current study aimed to determine a possible association between variants of the eNOS gene (variable number of tandem repeats in intron 4 and T786C) in SCD complications among Ghanaian patients. This was a cross-sectional study involving 89 HbSS patients with complications and 46 HbSS patients without complications. Genomic DNA was extracted from leukocytes in the buffy coat and separated from collected whole blood samples of the study participants. PCR amplification, followed by restriction fragment length polymorphism (RFLP) was used to genotype T786C (rs2070744) variants. Variable number of tandem repeats (VNTR) in intron 4 was genotyped by PCR and direct electrophoresis. There was a significant difference in the genotype frequency of the T786C variant between HbSS patients with complications and those without complications (p = 0.0165). However, there was no significant difference in the VNTR intron 4 variant of the eNOS gene between patients with complications and those without complications (p > 0.05). The study shows an association between the eNOS gene variant (T786C) and complications in SCD.

Towards Establishing Capacity for Biological Dosimetry at Ghana Atomic Energy Commission.

The aim of this study was not only to obtain basic technical prerequisites for the establishment of capacity of biological dosimetry at the Ghana Atomic Energy Commission (GAEC) but also to stimulate interest in biological dosimetry research in Ghana and Sub-Saharan Africa. Peripheral blood from four healthy donors was exposed to different doses (0-6 Gy) of gamma rays from a radiotherapy machine and lymphocytes were subsequently stimulated, cultured, and processed according to standard protocols for 48-50 h. Processed cells were analyzed for the frequencies of dicentric and centric ring chromosomes. Radiation dose delivered to the experimental model was verified using GafChromic® EBT films in parallel experiments. Basic technical prerequisites for the establishment of capacity of biological dosimetry in the GAEC have been realized and expertise in the dicentric chromosome assay consolidated. We successfully obtained preliminary cytogenetic data for a dose-response relationship of the irradiated blood lymphocytes. The data strongly indicate the existence of significant linear (α) and quadratic (ß) components and are consistent with those published for the production of chromosome aberrations in comparable absorbed dose ranges.

Radiosensitizing effect of rosmarinic acid in metastatic melanoma B16F10 cells.

BACKGROUND: Rosmarinic acid is an ester of caffeic acid with interesting biological activities including antioxidant effects and scavenging of oxygen-free radicals. AIM: To determine the potentially paradoxical effect of rosmarinic acid, typically being radioprotective when applied to non-tumorous cells, yet conversely displaying a sensitizing action when applied to metastatic B16F10 melanoma cells. MATERIALS AND METHODS: The genoprotective effect was studied by means of micronucleus tests for anti-mutagenic activity in which the reduction in the frequency of micronuclei was evaluated using cytokinesis-blocked human lymphocytes. The radioprotective effect was studied via a cell viability test in PNT2 (human prostate epithelium) and B16F10 melanoma cells. RESULTS: Rosmarinic acid exhibits a significant genoprotective capacity (p<0.001) against X-rays with a protection factor of 58%, and a dose reduction factor of 7.2. Cell survival obtained after exposure to 10 Gy of X-rays showed a protection factor of 47.5%, thus eliminating 29.1% of radiation-induced cell death in normal prostate epithelial cells (p<0.001). However, in metastatic B16F10 melanoma cells, rosmarinic acid acted not as a radioprotector, but as a sensitizing agent, increasing cellular death by 42% (p<0.001), with an enhancement ratio of 2.36. CONCLUSION: Rosmarinic acid has an increased capacity for producing radio-induced damage, and thus a paradoxical damaging effect in melanoma cells. Potentially, research into substances such as rosmarinic acid could help clarify mechanisms that provide protection on healthy normal cells, while exclusively damaging neoplastic cells, thus presenting a new strategy for patients undergoing radiotherapy for cancer.