Effect of long-term 50 Hz magnetic field exposure on the micronucleated polychromatic erythrocytes of mice.

In recent years extremely low-frequency magnetic fields (ELF-EMF) have become widely used in human activities, leading to an increased chance of exposure to ELF-EMF. There are few reports on in vivo mammalian genotoxic effects using micronucleus (MN) assays, which generally have been used as a short-term screening system. We analyzed the possible genotoxic effect induced by long-term exposure (7, 14, 21, 28 d) of a 50 Hz ELM-MF to mice by measuring the increase in frequency of micronucleated polychromatic erythrocyte in their bone marrow (MNPCEs) and we compared it with that induced by 50 cGy of X-rays. Subsequently, we tried to reduce this chromosomal damage by administering four antioxidants substances with radioprotective capacities: dimethyl sulfoxide (DMSO), 6-n-propyl-2-thiouracil (PTU), grape-procyanidins (P) and citrus flavonoids extract (CE). The increase in micronucleated cells was higher in both physical treatments (Control < ELF-EMF (p < 0.01) 0.001)); however, the antioxidant substances only showed a genoprotective capacity against the damage induced by ionizing radiation (Ci > PTU = DMSO (p < 0.001) >P = CE (p < 0.001). The 50 Hz ELM-MF increased MNPCEs in mouse bone marrow, expressing a genotoxic capacity. Administration of antioxidant substances with radioprotective capacities known to act through the elimination of free radicals did not diminish the genotoxic effect induced by ELM-MF.

Early Identification and Treatment of Trochlear Knee Dysplasia.

A shallow sulcus characterizes trochlear dysplasia (TD) of the femoral trochlea, which can lead to chronic pain or instability of the patellofemoral joint. Breech presentation at birth has been identified as a risk factor for developing this condition, which an ultrasound can identify early. Early treatment could be considered at this stage, given the potential for remodelling in these skeletally immature patients. Newborns with breech presentation at birth who meet the inclusion criteria will be enrolled and randomised in equal proportions between treatment with the Pavlik harness and observation. The primary objective is to determine the difference in the means of the sulcus angle between the two treatment arms at two months. Ours is the first study protocol to evaluate an early non-invasive treatment for TD in the newborn with breech presentation at birth using a Pavlik harness. We hypothesised that trochlear dysplasia could be reverted when identified and treated early in life with a simple harness, as it is done with developmental dysplasia of the hip.

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.

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.

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.

Effects of bisphosphonates in combination with ionizing radiation and antioxidants on the growth of prostate and melanoma cells lines.

BACKGROUND: Bisphosphonates are used in cancer-related hypercalcaemia, in complications of bone metastasis and in postmenopausal osteoporosis, and have often been associated with adverse complications. AIM: To determine the protective effect of apigenin against growth inhibition of normal epithelial human prostatic (PNT2), transgenic adenocarcinoma of mouse prostate (TRAMP-C1) and metastatic melanoma cells (B16F10) in combined treatments with bisphosphonates and ionizing radiation (IR). MATERIALS AND METHODS: The growth inhibition on PNT2, TRAMP-C1 and B16F10 cells in the combined treatments with bisphosphonates (zoledronic acid, ibandronate and pamidronate) and IR in the presence and absence of apigenin was studied using a cell viability test. RESULTS: Zoledronic acid had a cytotoxic effect on PNT2, TRAMP-C1 and B16F10 cells (p<0.001). However, ibandronate and pamidronate had a cytotoxic effect only on PNT2 cells (p<0.001). The administration of apigenin in combined treatment with bisphosphonates and IR showed: a decrease in the cytotoxic effect on TRAMP-C1 and B16F10 cells in the treatment with ibandronate; a protective effect on normal PNT2 and melanoma cells, but not on TRAMP-C1 cells in the treatment with zoledronic acid; and provided protection only to PNT2 cells in the treatment with pamidronate. CONCLUSION: The use of the antioxidant produced a greater decrease in the cytotoxic effect on the non-tumor than in tumor cells when treated with bisphosphonates-alone and could be used in non-tumor pathologies. However, in a combined treatment with IR, it can also provide protection to tumor cells, thus reducing the intended effect of the IR.