Application of dextran-coated iron oxide nanoparticles in enhancing the radiosensitivity of cancerous cells in radiotherapy with high-energy electron beams

Purpose: Nowadays, cancer is one of the most important causes of morbidity and mortality in the world. The ideal aim of radiotherapy is delivering a lethal radiation dose to tumor cells while minimizing radiation exposure to healthy tissues around the tumor. One way to increase the dose in the tumor cells is the use of high-atomic number nanoparticles as radiosensitizer agents in these cells. The aim of this in vitro study was investigating the radiosensitization enhancement potential of the dextran-coated iron oxide nanoparticles (IONPs) on HeLa and MCF-7 cell lines in irradiations with high-energy electron beams. Materials and Methods: In this in vitro study, the cytotoxicity level of dextran-coated IONPs at different concentrations (10, 40, and 80 μg/ml) was assessed on HeLa and MCF-7 cell lines. To evaluate the radiosensitivity effect, the nanoparticles were incubated with the cells at different concentrations for 24 h and afterward irradiated with different doses (0, 2, 4, 6, and 8 Gy) of 6 and 12 MeV electron beams. The cells survival fractions were obtained by the methylthiazoletetrazolium assay. Results: Toxicity results of the nanoparticles at 10 and 40 μg/ml concentrations showed no significant cytotoxicity effect. The cells survival rates in groups receiving radiation in the absence and presence of IONPs showed a significant difference. The radiosensitivity enhancement induced by the nanoparticles in MCF-7 cell line was more than it in HeLa cell line. The average of radiosensitization enhancement factor at 10, 40, and 80 μg/ml concentrations and under 6 MeV irradiations obtained as 1.13, 1.19, 1.25, and 1.26, 1.28, 1.29 for HeLa, and MCF-7 cells, respectively. When 12 MeV electron beams were carried out, the values of 1.17, 1.26, 1.32, and 1.29, 1.32, 1.35 were obtained for the cells at the mentioned concentrations, respectively. Furthermore, the significant differences were observed in radiosensitization enhancement between 6 and 12 MeV electron beams irradiations. Conclusion: Use of dextran-coated IONPs can increase radiosensitivity and consequently at a given absorbed dose more cell killing will occur in cancerous cells. In other words, these nanoparticles can improve the efficiency of electron therapy

The Experimental Assessment Of Build Up Factor And Attenuation Coefficient Of Brass Compensator Applied In Intensity-Modulated Radiation Therapy (Imrt) For 6mv Photon Beam

Introduction: Recent compensators are commonly applied in IMRT. The precise properties of applied compensators such as thickness, attenuation coefficient and build up factor are intensively important for IMRT calculations. Method: The brass compensator used for 6 MV photon beam was studied to estimate the relative effect of thickness and field size on IMRT calculations. Various field size together with several compensator thicknesses were examined. Result: The average reduction of effective attenuation coefficient (EAC), for the fields of 10×10 cm2 to 20×20 cm2, was 9.94%. By increasing the field size, EAC was decreased. The major reduction of EAC due to increasing field size was found to be 9.62%. The build up factor was increased by 2% to 21.8% respect to field size and compensator thickness. Also, the build up factor was increased by adding up the thickness. The rate of changes ranged from 24% to 48 %.Conclusion: The compensator thickness and field size are significantly important to calculate the effective attenuation coefficient and build up facto

Focal injection of Ethidium bromide as a simple model to study cognitive deficit and its improvement

Introduction: Memory and cognitive impairments are some of devastating outcomes of Multiple Sclerosis [MS] plaques in hippocampus, the gray matter part of the brain. The present study aimed to evaluate the intrahippocampal injection of Ethidium Bromide [EB] as a simple and focal model to assess cognition and gray matter demyelination

Methods: Thirty Wistar rats were divided into three groups: control group, which received saline, as solvent of EB, into the hippocampus; and two experimental groups, which received 3 microL of EB into the hippocampus, and then, were evaluated 7 and 28 days after EB injection [n=10 in each group], using a 5-day protocol of Morris Water Maze [MWM] task as well as Transmission Electron Microscopy [TEM] assay

Results: Seven days after EB injection, the behavioral study revealed a significance increase in travelled distance for platform finding in the experimental group compared to the control group. In addition, the nucleus of oligodendrocyte showed the typical clumped chromatin, probably attributed to apoptosis, and the myelin sheaths of some axons were unwrapped and disintegrated. Twenty-eight days after EB injection, the traveled distance and the time spent in target quadrant significantly decreased and increased, respectively in experimental groups compared to the control group. Also, TEM micrographs revealed a thin layer of remyelination around the axons in 28 days lesion group

Discussion: While intracerebral or intraventricular injection of EB is disseminated in different parts of the brain and can affect the other motor and sensory systems, this model is confined locally and facilitates behavioral study. Also, this project could show improvement of memory function subsequent to the physiological repair of the gray matter of the hippocampus

Administration of cannabinoid receptor antagonist into the ventral tegmental area could inhibit conditioned place preference induced by chemical stimulation of the lateral hypothalamus

Orexinergic projection originated from the lateral hypothalamus [LH] to the ventral tegmental area [VTA] has an important role in the acquisition of drug conditioned place preference [CPP]. In the present study, we tried to evaluate the effect of LH stimulation on conditioned place preference paradigm and role of CB1 receptors located in the VTA in development of reward-related behaviors in rats. One hundred twenty adult male Wistar rats weighing 220-330 g were unilaterally implanted by two separate cannulae into the LH and VTA. The CPP paradigm was done. Our findings showed that unilateral intra-LH administration of carbachol [62.5, 125 and 250 nmol/0.5 micro l saline], during conditioning phase, induced CPP in a dose-dependent manner. Additionally, intra-VTA administration of AM251 [5, 25 and 125 nmol/0.3 micro l DMSO] as a CB1 receptor antagonist, just 5 min before carbachol during the 3-day conditioning phase, could dose dependently inhibit the development of LH stimulation-induced CPP in the rats. It is supposed that the projection from LH to VTA is involved in LH chemical stimulation-induced CPP and CB1 receptor in the VTA has a modulatory role in this phenomenon

[Effects of reversible inactivation of the ventral tegmental area on the firing rate of neurons in the shell sub-region of the nucleus accumbens and on morphine-induced conditioned place preference in the rat]

The mesolimbic dopaminergic system that projects from the ventral tegmental area [VTA] to the nucleus accumbens [NAc] is critical for initiation of opioid reinforcement and reward-related effects of drugs of abuse. In the present study, the effects of reversible inactivation of VTA on firing rate of nucleus accumbens neurons and on acquisition and expression of morphine-induced conditioned place preference [CPP] were investigated in rats. Adult male Wistar rats were used in these experiments. In behavioral study, the reversible inactivation of VTA was done through bilateral intra-VTA microinjection of 2% lidocaine during the acquisition and expression of morphine [5 mg/kg; s.c.]-induced CPP and in electrophysiology section, it was done through unilateral intra-VTA microinjection of 2% lidocaine during single unit recording from the NAc neurons. Conditioning score and locomotor activity were recorded by Ethovision software. Firing rate of neurons was recorded by single unit recording technique. The results showed that bilateral intra-VTA administration of lidocaine significantly decreases the acquisition [P<0.01] and expression [P<0.05] of morphine-induced CPP compared to their respective saline-microinjected groups. Moreover, intra-VTA administration of lidocaine had no effect on locomotor activity in these experiments. Also, unilateral intra-VTA administration of lidocaine significantly increased the firing rate of nucleus accumbens neurons. Our results further support the idea that VTA may play an important role in the acquisition and expression of morphine-induced CPP

effect of nicotine administration on physical and psychological signs of withdrawal syndrome induced by single or frequent doses of morphine in rats

Morphine addiction and morphine withdrawal syndrome are the two main problems of today's human society. The present study has investigated the effects of nicotine on the strength of physical and psychological dependency in single and repeated doses morphine administrated rats. Male Wistar rats were subjected to morphine consumption with single or frequent dose protocols. In the single dose protocol, rats received only one dose of morphine and 24hrs later they also received one dose of nicotine 30 min prior to injection of naloxone. In the repeated dose protocol, rats received incremental doses of morphine for 7 days and 24hr after the last dose [the 8th day] were given naloxone. However, the nicotine regimen of this group was injected 15 min before the morphine injection, for 4 days, from the 4th to the 7th day. Five minutes after naloxone injection, each rat's behavior was captured for 30 min, and then physical and psychological signs of withdrawal syndrome were recorded. Data were analyzed by ANOVA followed by Tukey tests and p<0.05 was considered as significant difference. Results showed that the injection of frequent and single doses of morphine lead to morphine dependency. In single dose protocol, nicotine consumption attenuated the signs of withdrawal syndrome, especially weight of excrement and total withdrawal score. In frequent dose protocol, in addition to these effects, nicotine induced weight loss and place aversion. The inhibitory effects of nicotine on signs of withdrawal syndrome may involve a dopaminergic portion of the central nervous system and is mediated by central nicotinic receptors. There is also a cross-dependence between nicotine and morphine

brief look into spike sorting methods

Spike sorting is a class of techniques used in the analysis of electrophysiological data. Studying the dynamics of neural activity via electrical recording relies on the ability to detect and sort neural spikes recorded from a number of neurons by the same electrode. This article reviews methods for detecting and classifying action potentials, a problem commonly referred to as spike sorting

Glutamate receptors in nucleus accumbens can modulate canabinoid-induced antinociception in rat's basolateral amygdala

It has been shown that administration of WIN55,212-2, a cannabinoid receptor agonist, into the basolateral amygdala [BLA], dose-dependently increases the thermal latency to withdrawal in the tail-flick test and decreases pain related behaviors in both phases of the formalin test. Recent human and animal imaging data suggest that the nucleus accumbens [NAc] is an important neural substrate of pain modulation. Because the NAc also receives abundant glutamatergic fibers from the BLA which converge with hippocampal fibers on the same NAc neurons, it is reasonable to ask whether AMPA/kainate and NMDA receptor antagonists may also include in the amygdala-accumbens pathway in pain modulation. In the present study, we examined the role of NMDA and AMPA/kainate receptors within the NAc in antinociception induced by intra-BLA injection of the cannabinoid receptor agonist WIN55,212-2 in rats. Seventy two adult male albino Wistar rats weighing 230-280 g were implanted with two separate cannulae into the BLA and the NAc. Also, animals received intra-accumbal infusions of either NMDA receptor antagonist, AP5 [0.5, 2.5 and 5 microg/0.5 ul saline] or AMPA/kainate receptor antagonist, CNQX [0.1,0.5 and 2.5 pg/0.5 microl DMSO] 2 min before microinjection of WIN55,212-2 into the BLA[15 microg/rat]. Antinociceptive effects of WIN55,212-2 were measured in the formalin test [50 microl injection of formalin 2.5% subcutaneously into the hindpaw] and pain-related behaviors were monitored for 60 min. Results showed that intra-accumbal AP5 and CNQX dose-dependently prevented antinociception induced by intra-BLA administration of WINS5,212-2 in time set intervals. Additionally, intra-accumbal APS administration of both APS [5 microg/0.5 microl saline] and CNQX [2.5 microg/0.5 microl DMSO], alone, could not significantly change the pain scores in the rats. It seems that glutamate receptors located in the NAc, partially mediate the antinociceptive responses of cannabinoid within the BLA in persistent inflammatory model of pain

assessment of the factors involved in effective attenuation coefficient of the compensator material for the treatment with 6MV photons using intensity modulated radiation therapy method

One of the intensity modulated radiation therapy [IMRT] methods is based on using compensators. The most important factor in designing a compensator is the accurate calculation of its thickness to achieve the intensity modulation of interest. To achieve that, the exact attenuation coefficient of compensator materials must be calculated. However, there are several parameters that are effective in calculating the attenuation coefficient of compensator materials. In this research, the effects of dosimeter and phantom type as well as irradiation dose and measurement depth in the calculation of this compensator characteristic were assessed. Using two types of dosimeters [RK and FC65G] and phantoms [RFA300plus and SP34], the effects of radiation dose and measured depth on the estimation of the effective attenuation coefficient was investigated for a 6MV linear accelerator. The value of applied radiation dose was 100, 200, 300 and 400 cGy, and the measured depths were 2, 5, 10, 15 and 20 cm. The measurements were carried out at the reference field size [10x10 cm[2]] and for a thickness of 1 cm of the compensator. The results indicated that radiation dose has no significant effect in calculating the effective attenuation coefficient of compensator materials. However, altering measured depth from 2 to 20 cm resulted in a change of more than 5% in the calculations. In addition, the type of the dosimeter and phantom used in this study had no significant effect on the calculations. Based on these findings, it is recommended that for more accurate estimation of the effective attenuation coefficient of a compensator material, it is necessary to measure the attenuation coefficient at different depths of the treatment field

Blockade of the naloxone-induced aversion in morphine-conditioned wistar rats by L-arginine intra-central amygdale

Single injection of naloxone, a selective antagonist of morphine, prior to the drug conditioning testing was used to investigate on morphine dependence. Conditioning to morphine [2.5-10 mg/kg, s.c.] was established in adult male Wistar rats [weighing 200-250 g] using an unbiased procedure. Nitric oxide agents were microinjected into the central amygdale prior to naloxone-paired place conditioning testing. The results showed that morphine produced a significant dose-dependent place preference in animals. Naloxone [0.1-0.4 mg/kg, i.p.] injections pre-testing of the response to morphine [7.5 mg/kg, s.c.] caused a significant aversion at the higher doses [0.4 mg/kg, i.p.]. This response was reversed by microinjection of L-arginine [0.3-3 micro g/rat, intra-central amygdale] prior to naloxone on the day of the testing. The response to L-arginine was blocked by pre-injection of N[G]-nitro-L-arginine methyl ester [L-NAME] intra-central amygdale]. A single injection of naloxone on the test day of morphine place conditioning may simply reveal the occurrence of morphine dependence in rats, and that the nitric oxide in the central amygdale most likely plays a key role in this phenomenon

Capsazepine, a transient receptor potential vanilloid type 1 [TRPV1] antagonist, attenuates antinociceptive effect of CB1 receptor agonist, WIN55,212-2, in the rat nucleus cuneiformis

Introduction: Nucleus cuneiformis [NCF], as part of descending pain inhibitory system, cooperates with periaqueductal gray [PAG] and rostral ventromedial medulla [RVM] in supraspinal modulation of pain. Cannabinoids have analgesic effects in the PAG, RVM and NCF. The transient receptor potential vanilloid type 1[TRPV1] can be activated by anandamide and WIN55, 212-2 as a cannabinoid receptor agonist. The aim of the current study is to investigate the possible interplay between the cannabinoid and vanilloid systems for modulation of pain at the NCF. Methods: In this study, a cannabinoid receptor agonist, WIN55, 212-2 [15 µg/0.3 µl DMSO], and selective TRPV1 receptor antagonist, capsazepine [10, 25, 50 and100 nmol/0.3 µl DMSO], were microinjected bilaterally into the NCF, and tailflick and formalin tests were used to assess the animal's pain-related behaviors at 5-min intervals for a 60-min period. Results: Our findings demonstrated that analgesic effect of WIN55, 212-2 were dose-dependently attenuated by capsazepine in both tests. In the tail-flick test, capsazepine at both doses of 50 [P<0.01] and 100 [P<0.001] nmol could significantly prevent the antinociceptive effect of WIN55, 212-2 while capsazepine, in formalin test, could decreased its antinociceptive effect at the dose of 50 nmol [P<0.05] as well. On the other hand, solely administration of the highest dose of capsazepine in both tests did not alter the pain-related behaviors. Discussion: It suggests a possible role for TRPV1 receptors in NCF-mediated cannabinoid-induced antinociception

effects of lidocaine reversible inactivation of the dorsal raphe nucleus on passive avoidance learning in rats

Introduction: The role of serotonergic fibers in avoidance learning is controversial. Involvement of the dorsal raphe nucleus [DRN], the main source of hippocampal projecting serotonergic fibers in acquisition, consolidation and retrieval of passive avoidance [PA] learning, was investigated by functional suppression of this area. Materials and Methods: DRN functional inactivation was done by lidocaine [0.5µl, 2%] injection into the DRN, 5 min before training [n=10]; and 5 [n=9], 90 [n=10] and 360 min [n=9] after acquisition trial. In the last experiment, lidocaine was injected into the DRN 5 min before the retrieval test, which was 48 h after the training [n=10]. Results: Our results showed that PA learning was not impaired by DRN inactivation 5 min before training nor 5 and 360 min after training. Lidocaine injected 90 min after the acquisition trial significantly reduced avoidance of the dark compartment [P<0.001]. Intra-DRN injection of lidocaine before retrieval significantly increased PA retention [P<0.001]. Therefore, it seems that DRN has opposite effects on consolidation and retrieval of passive avoidance learning, but it has no effect on PA acquisition. Discussion: It is suggested that functional ablation of DRN may disrupt integrity of subcortical circuits participating in PA consolidation, but DRN inactivation by increasing brain awareness may affect PA retrieval in rats

Contribution of the nucleus cuneiformis to the antinociceptive effects of systemic morphine on inflammatory pain in rats

The role of midbrain reticular formation, which includes the nucleus cuneiformis [NCF], as a crucial antinociceptive region in descending pain modulation has long been investigated. In this study, we tried to highlight the role of NCF in morphine-induced antinociception in formalin-induced pain model in rats. A total of 201 male Wistar rats weighing 260-310 g were used in this study. The effective dose of morphine in systemic administration [intraperitoneal; i.p.] was determined after a dose- and time-response protocol. In consequent groups, bilateral electrolytic lesion [500 microA, 30 sec] or reversible inactivation [lidocaine 2%] were used in the NCF before systemic administration of morphine, and then, the nociceptive test was immediately carried out. The results showed that administration of 6 mg/kg morphine, 30 min before the formalin test, is the best dose- and time-response set in these experiments. The obtained data also indicated that bilateral electrical destruction or reversible inactivation of the NCF significantly decreased antinociceptive responses of systemic morphine [6 mg/kg; i.p.] during the second phase of formalin test [P<0.05]. Therefore, it seems that opioid receptors located in the NCF may be involved in modulation of central sensitization which occurred in inflammatory pain in rats

Blockade of opioid receptors located in the rat nucleus cuneiformis reduced the antinociceptive responses of local but not systemic administration of morphine in formalin test

Previous studies have shown the role of opioid receptors located in the nucleus cuneiformis [CnF] in acute pain, but not in chronic pain models. In the present study, we have determined that possible effects of these receptors at the CnF on both early and late phases of formalin test following local and systemic morphine administration. Each rat was given a subcutaneous 50-p.1 injection of 2.5% formalin into plantar surface of hind paw. Ninety five Wistar rats bilaterally received morphine [1, 2, 4 and 8 p.g/0.3 p.1 saline per side] into the CnF, just before the formalin test. Naloxone [I p.g/0.3 p1 saline per side] was also microinjected 2 minutes before local or 28 minutes after intraperitoneal administration of morphine. The results showed that bilateral intra-CnF administration of morphine dose-dependently produced analgesia in formalin test. Naloxone administration into the CnF antagonized the analgesic response induced by morphine [4 p.g/0.3 p.1 saline] microinjection. The results also showed that analgesic effect of systemic morphine was not significantly decreased by naloxone microinjection. We suggest that the opioid receptors located in the CnF, in part, indirectly affect the morphine-induced descending pain modulatory circuit

lidocaine acts in morphine dependency

To study the effect of analgesia caused by a local anesthetic agent [Lidocaine] in morphine dependent and independent rats. We carried out this experimental study in the Neuroscience Research Center of Kerman Medical University, Iran in 2003. We evaluated 2 groups of morphine dependent and independent rats. Morphine dependency was induced orally, and formalin was used as a noxious stimulus. The orofacial formalin test in rats is a valid and reliable model of nociception. The formalin test induces 2 distinct periods of nociception reaction, the first phase occurs in the first 3 minutes and the second phase 15-45 minutes later. The behavioral response of the animals to the noxious stimulus [formalin] was measured by the time the animal spent rubbing the injected area. All the injections were carried out subcutaneously into the upper lip of the animal, at the same site if possible. The effect of morphine dependency on local analgesia was assessed by injection of 50 micro L lidocaine prior to 50 micro L diluted formalin [2.5% in saline] in one group, and after formalin in the other group. Subcutaneous injection of lidocaine prior to morphine completely abolished the first phase of formalin nociceptive response in both morphine dependent and independent rats. Injection of lidocaine after formalin did not affect the first phase in both groups, but abolished the first part of the second phase in both groups. Considering different mechanisms of morphine and lidocaine in the body, the results verified that the analgesia induced by lidocaine in both morphine dependent and independent groups was the same, and we do not need higher doses of lidocaine to suppress formalin induced pain in the morphine dependent group