Samara Cristina Ferreira-Machado

Up-regulation of angiotensin-converting enzyme and angiotensin II type 1 receptor in irradiated rats

Purpose: To investigate changes in cardiac functional parameters and the cardiac expression of angiotensin-converting enzyme (ACE), angiotensin II type 1 receptor (AT1), procollagen type I (proc-I) and transforming growth factor-β1 (TGF-β1) in rats irradiated at heart. Material and methods: Male Wistar rats were irradiated with a single dose of radiation (0, 5, 10 and 15 Gray [Gy]) delivered directly to the heart and the molecular evaluations were performed at various times post-irradiation (two days, 15 days and four months). The expression of ACE, AT1, proc-I and TGF-β1 were analysed using Real Time-Polymerase Chain Reaction (RT-PCR) and/or Western blotting. Cardiac structural and functional alterations were investigated at the four-month time point by echocardiography and by quantitative methods (stereology). Results: Rats irradiated with 15 Gy showed a modest reduction in the ejection fraction. Cardiac proc-I, TGF-β1, ACE and AT1 were also measurably increased. Conclusions: Irradiated rat hearts show simultaneous elevations in renin-angiotensin system components AT1 and ACE and cardiac remodeling markers proc-I and TGF-β1.

Chemotherapy and radiation regimens to breast cancer treatment induce changes in mRNA levels of renin-angiotensin system related genes in cardiac tissue

Background and aim: Cardiovascular complications are one limitation of breast cancer treatment. The aim of the current study was to investigate whether the renin–angiotensin related genes could be altered by chemotherapy and radiotherapy, using a rat model. Methods: Female rats were divided into three groups: control, chemotherapy + irradiation (TC+IR) and irradiation (IR). Molecular analyses of the left ventricle were performed five months after the end of treatment. The analyses evaluated the changes in mRNA levels of some renin–angiotensin system (RAS) related genes: angiotensinogen, renin, angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT1) and vascular endothelial growth factor (VEGF), which can be related to ACE production, by RT-PCR. Results: Renin was only observed in treated groups, TC+IR and IR, compared with the control group. ACE and VEGF levels were decreased in TC+IR (p<0.001) and in IR (p<0.001), and AT1 mRNA was higher in groups TC+IR (p<0.01) and IR (p<0.05) compared with the control group. Conclusion: Chemotherapy and irradiation can induce significant changes in some RAS related genes. These alterations are important to understand the pathways and consequences beyond cardiotoxicity induced by breast cancer treatments.

Low-intensity infrared lasers alter actin gene expression in skin and muscle tissue

The biostimulative effect of low-intensity lasers is the basis for treatment of diseases in soft tissues. However, data about the influence of biostimulative lasers on gene expression are still scarce. The aim of this work was to evaluate the effects of low-intensity infrared lasers on the expression of actin mRNA in skin and muscle tissue. Skin and muscle tissue of Wistar rats was exposed to low-intensity infrared laser radiation at different fluences and frequencies. One and 24 hours after laser exposure, tissue samples were withdrawn for total RNA extraction, cDNA synthesis and evaluation of actin gene expression by quantitative polymerase chain reaction. The data obtained show that laser radiation alters the expression of actin mRNA differently in skin and muscle tissue of Wistar rats depending of the fluence, frequency and time after exposure. The results could be useful for laser dosimetry, as well as to justify the therapeutic protocols for treatment of diseases of skin and muscle tissues based on low-intensity infrared laser radiation.

DNA fragmentation and nuclear phenotype in tendons exposed to low-intensity infrared laser

Clinical protocols are recommended in device guidelines outlined for treating many diseases on empirical basis. However, effects of low-intensity infrared lasers at fluences used in clinical protocols on DNA are controversial. Excitation of endogenous chromophores in tissues and free radicals generation could be described as a consequence of laser used. DNA lesions induced by free radicals cause changes in DNA structure, chromatin organization, ploidy degrees and cell death. In this work, we investigated whether low-intensity infrared laser therapy could alter the fibroblasts nuclei characteristics and induce DNA fragmentation. Tendons of Wistar rats were exposed to low-intensity infrared laser (830 nm), at different fluences (1, 5 and 10 J/cm2), in continuous wave (power output of 10mW, power density of 79.6 mW/cm2). Different frequencies were analyzed for the higher fluence (10 J/cm2), at pulsed emission mode (2.5, 250 and 2500 Hz), with the laser source at surface of skin. Geometric, densitometric and textural parameters obtained for Feulgen-stained nuclei by image analysis were used to define nuclear phenotypes. Significant differences were observed on the nuclear phenotype of tendons after exposure to laser, as well as, high cell death percentages was observed for all fluences and frequencies analyzed here, exception 1 J/cm2 fluence. Our results indicate that low-intensity infrared laser can alter geometric, densitometric and textural parameters in tendon fibroblasts nuclei. Laser can also induce DNA fragmentation, chromatin lost and consequently cell death, using fluences, frequencies and emission modes took out from clinical protocols.

Common Deletion (CD) in mitochondrial DNA of irradiated rat heart

The purpose of this study was to map the common deletion (CD) area in mtDNA and investigate the levels of this deletion in irradiated heart. The assays were developed in male Wistar rats that were irradiated with three different single doses (5, 10 or 15 Gy) delivered directly to the heart and the analyses were performed at various times post-irradiation (3, 15 or 120 days). The CDs area were sequenced and the CD quantified by real-time PCR. Our study demonstrated that the CD levels progressively decreased from the 3rd until the 15th day after irradiation, and then increased thereafter. Additionally, it was observed that the levels of CD are modulated differently according to the different categories of doses (moderate and high). This study demonstrated an immediate response to ionizing radiation, measured by the presence of mutations in the CD area and a decrease in the CD levels.

Analysis of calcium distribution in femur of female rats submitted to different chemotherapy regimens

The most used treatment strategies for breast cancer (BC) are surgery, chemotherapy, and/or radiotherapy. Premenopausal women undergoing adjuvant chemotherapy BC treatment have significant bone loss from the first year after the treatment. This high bone mineral density loss can lead to an increased risk of fractures. Doxorubicin associated with Cyclophosphamide (AC) is a multidrug widely used for BC treatment, although this association can cause severe side effects. Today it is been discussed the use of the Docetaxel and cyclophosphamide (TC) association for BC treatment. The influence on the bone during chemotherapy regimens that include taxanes, like docetaxel, is unknown. Data from the “Women`s Health Initiative” show that postmenopausal BC survivors have a 15% greater risk of developing fractures than women without a history of BC. In this study, it was evaluated parameters involved in osteoporosis when rats were subjected to a chemotherapy regimen (TC) and/or irradiation (IR). Female Wistar rats, 03 months old, were divided into 3 groups: control, TC+IR (G1) and AC+IR (G2). The animals were euthanized 5 after months the end of treatment and their femurs were excised and dissected. Sections of 10 μm thick were used for μXRF analysis at the National Laboratory of Synchrotron Light. The uteri of these rats were collected and weighed Statistical analyzes were performed using GraphPad Prism, and values were compared using ANOVA and Tukey post-hoc test. The obtained results showed that animals from G2 had a significant reduction (p<;0.05) of uterine mass when compared to control. The qualitative analysis performed by μXRF showed that the animals from G2 had iron in bone composition of the femurs. This same result was not observed in animals from G0 and G1 groups. These results suggest that early menopause occurs and osteoporosis begins, probably because of the absence, or reduced, production of estrogen. The presence of iron in the G2 samples indicates the process of osteoporosis, because according to literature, this ion is competitive with calcium ions.