Effect of Pulsed Low-Level Lasers on Adult versus Neonatal Human Retinal Pigment Epithelial Cells: An in-vitro Study.

Purpose: To investigate the short-term effects of low-level lasers (LLLs; also known as low-power laser therapy) on the structure, genetic, and phenotype of cultured human retinal pigment epithelial (hRPE) cells from both adult and neonatal sources. Methods: Cultivated adult and neonatal hRPE cells were irradiated with two types of LLL (630 nm and 780 nm), 1 min daily for five consecutive days. Results: An increase in doubling time was observed in 630 nm-irradiated adult hRPE cells (P = 0.032). The gene expression profile revealed increased expression of retinoid isomerohydrolase RPE65 (RPE65) (P < 0.01 for 630 nm laser, P < 0.001 for 780 nm laser) and nestin (NES) (P < 0.01 for 630 nm laser) in neonatal hRPE cells, upregulation of RPE65 (P < 0.001 for 780 nm laser) and paired box 6 (PAX6) (P < 0.001 for 780 nm laser) genes in adult hRPE cells, and reduced expression of actin alpha 2 (ACTA2) in 780 nm-irradiated adult hRPE cells (P < 0.001). Except the significant increase of α -SMA in 780 nm-irradiated neonatal hRPE cells, no significant change was noted in the expressions of other investigated proteins. Conclusion: Short-term irradiation of neonatal and adult hRPE cells with LLLs may induce multipotency at the transcriptional level. Irradiation of neonatal hRPE cells with LLLs can be associated with increased risk of myofibroblastic transformation; however, adult hRPE cells irradiated with the 780 nm laser have minimal risk of myofibroblastic differentiation. It seems that the 780 nm laser may be a promising option for future photobiomodulation in retinal degenerations in adults.

The Abundance of Plasmid-Mediated Quinolone Resistance Genes in Enterobacter cloacae Strains Isolated from Clinical Specimens in Kermanshah, Iran.

Background: Enterobacter cloacae (E. cloacae) is one of the most common Enterobacteriaceae causing nosocomial infections. Plasmid-mediated quinolone resistance (PMQR) determinants have been considered recently. This study evaluated the abundance of PMQR genes in strains of E. cloacae obtained from clinical samples in Kermanshah, Iran. Methods: In this descriptive cross-sectional study, after collecting 113 isolates of E. cloacae, their identity was confirmed using specific biochemical tests. After determining their drug resistance patterns using disc diffusion, the phenotypic frequency of extended-spectrum beta-lactamase (ESBL)-producing isolates was measured by the double-disk synergy test (DDST) method. The isolates were examined for the presence of qnrA, qnrB, qnrS, and aac(6')-Ib-cr genes by the polymerase chain reaction (PCR) assay. Results: The antibiotic resistance rate of E. cloacae isolates varied from 9.7% to 60.2%; among them, 78% were multidrug-resistant (MDR). The highest quinolone resistance was observed in ESBL-producing strains of E. cloacae. The frequency of positive isolates for PMQR and ESBL was 79.6% and 57.5%, respectively. The genes aac(6')-ib-cr (70.8%) and qnrB (38.1%) had the highest frequency among other genes. The number of isolates simultaneously carrying 2 and 3 genes was 64 and 5 isolates, respectively. Conclusion: The obtained results indicate a high degree of quinolone resistance among ESBL-producing E. cloacae strains. Nevertheless, there was a significant relationship between the PMQR gene and ESBL-positive isolates. Therefore, special attention should be paid to molecular epidemiological studies on antibiotic resistance to quinolones and beta-lactamases in these strains.

Measurement of Thermal Conductivity and Thermal Diffusivity of Porcine and Bovine Kidney Tissues at Supraphysiological Temperatures up to 93 °C.

This experimental study aimed to characterize the thermal properties of ex vivo porcine and bovine kidney tissues in steady-state heat transfer conditions in a wider thermal interval (23.2-92.8 °C) compared to previous investigations limited to 45 °C. Thermal properties, namely thermal conductivity (k) and thermal diffusivity (α), were measured in a temperature-controlled environment using a dual-needle probe connected to a commercial thermal property analyzer, using the transient hot-wire technique. The estimation of measurement uncertainty was performed along with the assessment of regression models describing the trend of measured quantities as a function of temperature to be used in simulations involving heat transfer in kidney tissue. A direct comparison of the thermal properties of the same tissue from two different species, i.e., porcine and bovine kidney tissues, with the same experimental transient hot-wire technique, was conducted to provide indications on the possible inter-species variabilities of k and α at different selected temperatures. Exponential fitting curves were selected to interpolate the measured values for both porcine and bovine kidney tissues, for both k and α. The results show that the k and α values of the tissues remained rather constant from room temperature up to the onset of water evaporation, and a more marked increase was observed afterward. Indeed, at the highest investigated temperatures, i.e., 90.0-92.8 °C, the average k values were subject to 1.2- and 1.3-fold increases, compared to their nominal values at room temperature, in porcine and bovine kidney tissue, respectively. Moreover, at 90.0-92.8 °C, 1.4- and 1.2-fold increases in the average values of α, compared to baseline values, were observed for porcine and bovine kidney tissue, respectively. No statistically significant differences were found between the thermal properties of porcine and bovine kidney tissues at the same selected tissue temperatures despite their anatomical and structural differences. The provided quantitative values and best-fit regression models can be used to enhance the accuracy of the prediction capability of numerical models of thermal therapies. Furthermore, this study may provide insights into the refinement of protocols for the realization of tissue-mimicking phantoms and the choice of tissue models for bioheat transfer studies in experimental laboratories.

Brain structural analysis in patients with post-traumatic anosmia: Voxel-based and surface-based morphometry.

PURPOSE AND BACKGROUND: Voxel-based morphometry (VBM) and surfaced-based morphometry (SBM) investigate the characteristics of gray matter (GM) in various diseases such as post-traumatic anosmia (PTA). This study uses SBM and VBM to examine neuroanatomical measurements of GM and its functional correlates in patients with PTA. METHODS: MRI images and olfactory test results were collected from 39 PTA patients and 39 healthy controls. Sniffin' Sticks test was used to assess olfactory function. GM structure was analyzed using CAT12 and FreeSurfer, and olfactory bulb (OB) volume and olfactory sulcus (OS) depth were calculated using 3D-Slicer. RESULTS: Anosmic patients showed lower scores in the Sniffin' Sticks olfactory test, as well as reduction of OB volume and OS depth compared to control subjects. In these patients, overlapping changes were found between the VBM and SBM findings in the areas with significant effects, in particular, orbitofrontal cortex, superior and middle frontal gyrus, superior and middle temporal gyrus, anterior cingulate cortex, and insular cortex. Using SBM, decreased cortical thickness clusters were located in inferior and superior parietal gyrus. Further analysis in the region of interest demonstrated correlations between the orbitofrontal cortex and odor threshold score as well as the middle frontal gyrus and smell loss duration. CONCLUSION: These findings show that the morphological alterations in the OB, OS, and the central olfactory pathways might contribute to the pathogenic mechanism of olfactory dysfunction after head injury.

Resilience assessment of centralized and distributed food systems.

Resilience, defined as the ability of a system to adapt in the presence of a disruptive event, has been of great interest with food systems for some time now. The goal of this research was to build understanding about resilient food systems that will withstand and recover from disruptions in a way that ensures a sufficient supply of food for all. In large, developed countries such as the USA and Canada, the food supply chain relies on a complex web of interconnected systems, such as water and energy systems, and food production and distribution are still very labor-intensive. Thanks to economies of scale and effective use of limited resources, potential cost savings support a push towards a more centralized system. However, distributed systems tend to be more resilient. Although distributed production systems may not be economically justifiable than centralized ones, they may provide a more resilient alternative. This study focused on the supply-side aspects of the food system and the food system's water, energy, and workforce disruptions to be considered for the resilience assessment for the USA, with an example for the state of Texas. After the degree of centralization (DoC) was calculated, the resilience of a food system was measured. Next, the relationship between labor intensity and production of six major food groups was formulated. The example for Texas showed that the decentralization of food systems will improve their resilience in responding to energy and water disruptions. A 40 percent reduction in water supply could decrease the food system performance by 28%. A negative correlation was found between the resilience and DoC for energy disruption scenarios. A 40 percent reduction in energy supply could decrease the food system performance by 34%. In contrast, achieving a more resilient food system in responding to labor shortage supports a push towards a more centralized system the decentralization of food systems can in fact, improve their resilience in responding to disruptions in the energy and water inputs. In contrast, achieving a more resilient food system in responding to labor shortage supports a push towards a more centralized system. Supplementary Information: The online version contains supplementary material available at 10.1007/s12571-022-01321-9.

Gold Nanoparticles-Mediated Photothermal Therapy of Pancreas Using GATE: A New Simulation Platform.

This work presents the first investigation of gold nanorods (GNRs)-based photothermal therapy of the pancreas tumor using the Monte Carlo-based code implemented with Geant4 Application for Emission Tomography (GATE). The model of a human pancreas was obtained by segmenting an abdominal computed tomography (CT) scan, and its physical and chemical properties, were obtained from experimental and theoretical data. In GATE, GNRs-mediated hyperthermal therapy, simple heat diffusion as well as interstitial laser ablation were then modeled in the pancreas tumor by defining the optical parameters of this tissue when it is loaded with GNRs. Two different experimental setups on ex vivo pancreas tissue and GNRs-embedded water were devised to benchmark the developed Monte Carlo-based model for the hyperthermia in the pancreas alone and with GNRs, respectively. The influence of GNRs on heat distribution and temperature increase within the pancreas tumor was compared for two different power values (1.2 W and 2.1 W) when the tumor was exposed to 808 nm laser irradiation and with two different laser applicator diameters. Benchmark tests demonstrated the possibility of the accurate simulating of NPs-assisted thermal therapy and reproducing the experimental data with GATE software. Then, the output of the simulated GNR-mediated hyperthermia emphasized the importance of the precise evaluation of all of the parameters for optimizing the preplanning of cancer thermal therapy. Simulation results on temperature distribution in the pancreas tumor showed that the temperature enhancement caused by raising the power was increased with time in both the tumor with and without GNRs, but it was higher for the GNR-load tumor compared to tumor alone.

A machine learning-driven spatio-temporal vulnerability appraisal based on socio-economic data for COVID-19 impact prevention in the U.S. counties.

A mature and hybrid machine-learning model is verified by mature empirical analysis to measure county-level COVID-19 vulnerability and track the impact of the imposition of pandemic control policies in the U.S. A total of 30 county-level social, economic, and medical variables and a timeline of the imposed policies constitutes a COVID-19 database. A hybrid feature-selection model composed of four machine-learning algorithms is developed to emphasize the regional impact of community features on the case fatality rate (CFR). A COVID-19 vulnerability index (COVULin) is proposed to measure the county's vulnerability, the effects of model's parameters on mortality, and the efficiency of control policies. The results showed that the dense counties in which minority groups represent more than 45% of the population and those with poverty rates greater than 24% were the most vulnerable counties during the first and the last pandemic peaks, respectively. Highly-correlated CFR and COVULin scores indicated a close agreement between the model outcomes and COVID-19 impacts. Counties with higher poverty and uninsured rates were the most resistant to government intervention. It is anticipated that the proposed model can play an essential role in identifying vulnerable communities and help reduce damages during long-term alike disasters.

Experimental Evaluation of Radiation Response and Thermal Properties of NPs-Loaded Tissues-Mimicking Phantoms.

Many efforts have recently concentrated on constructing and developing nanoparticles (NPs) as promising thermal agent for optical hyperthermia and photothermal therapy. However, thermal energy transfer in biological tissue is a complex process involving different mechanisms such as conduction, convection, radiation. Therefore, having information about thermal properties of tissue especially when NPs are embedded in is a necessity for predicting the heat transfer during hyperthermia. In this work, the thermal properties of solid phantom based on agar in the presence of three different nanoparticles (BPSi, tNAs, GNRs) and alone were measured and reported as a function of temperature (ranging from 22 to 62 °C). The thermal response of these NPs to an 808 nm laser beam with three different powers were studied in the water comparatively. Agar and tNAs have almost constant thermal properties in the considered range. Among the three NPs, gold has the highest conductivity and diffusivity. At 62 °C BPSi NPs have the similar amount of increase for the diffusivity. The thermal parameters reported in this paper can be useful for the mathematical modeling. Irradiation of the NPs-loaded water phantom displayed the highest radiosensitivity of gold among the three mentioned NPs. However, for the higher power of irradiation, BPSi and tNAs NPs showed the increased absorption of heat during shorter time and the increased temperature gradient slope for the initial 15 s after the irradiation started. The three NPs showed different thermal and irradiation response behavior; however, this comparison study notes the worth of having information about thermal parameters of NPs-loaded tissue for pre-clinical planning.

Reorganizing brain structure through olfactory training in post-traumatic smell impairment: An MRI study.

PURPOSE AND BACKGROUND: Post-traumatic olfactory dysfunction (PTOD), mostly caused by head injury, is thought to be associated with changes in the structure and function of the brain olfactory processing areas. Training and repeated exposure to odorants lead to enhanced olfactory capability. This study investigated the effects of a 16-weeks olfactory training (OT) on olfactory function and brain structure. METHODS: Twenty-five patients with PTOD were randomly divided in three groups: (1) 9 control patients who did not receive any training, (2) 9 patients underwent classical OT by 4 fixed odors, and (3) 7 patients underwent modified OT coming across 4 sets of 4 different odors sequentially. Before and after the training period, all patients performed olfactory function tests and structural magnetic resonance imaging (MRI). Sniffin' Sticks test was used to assess olfactory function. MRI data were analyzed using voxel-based morphometry and surface-based morphometry. RESULTS: Both trained groups showed a considerable recovery of olfactory function, especially in odor identification. MRI data analysis revealed that the classical OT leads to increases in cortical thickness/density of several brain regions, including the right superior and middle frontal gyrus, and bilateral cerebellums. In addition, the modified OT yielded a lower extent of cortical measures in the right orbital frontal cortex and right insular. Following modified OT, a positive correlation was observed between the odor identification and the right orbital frontal cortex. CONCLUSION: Both olfactory training methods can improve olfactory function and that the improvement is associated with changes in the structure of olfactory processing areas of the brain.

Measurement of Ex Vivo Liver, Brain and Pancreas Thermal Properties as Function of Temperature.

The ability to predict heat transfer during hyperthermal and ablative techniques for cancer treatment relies on understanding the thermal properties of biological tissue. In this work, the thermal properties of ex vivo liver, pancreas and brain tissues are reported as a function of temperature. The thermal diffusivity, thermal conductivity and volumetric heat capacity of these tissues were measured in the temperature range from 22 to around 97 °C. Concerning the pancreas, a phase change occurred around 45 °C; therefore, its thermal properties were investigated only until this temperature. Results indicate that the thermal properties of the liver and brain have a non-linear relationship with temperature in the investigated range. In these tissues, the thermal properties were almost constant until 60 to 70 °C and then gradually changed until 92 °C. In particular, the thermal conductivity increased by 100% for the brain and 60% for the liver up to 92 °C, while thermal diffusivity increased by 90% and 40%, respectively. However, the heat capacity did not significantly change in this temperature range. The thermal conductivity and thermal diffusivity were dramatically increased from 92 to 97 °C, which seems to be due to water vaporization and state transition in the tissues. Moreover, the measurement uncertainty, determined at each temperature, increased after 92 °C. In the temperature range of 22 to 45 °C, the thermal properties of pancreatic tissue did not change significantly, in accordance with the results for the brain and liver. For the three tissues, the best fit curves are provided with regression analysis based on measured data to predict the tissue thermal behavior. These curves describe the temperature dependency of tissue thermal properties in a temperature range relevant for hyperthermia and ablation treatments and may help in constructing more accurate models of bioheat transfer for optimization and pre-planning of thermal procedures.

Laser-induced thermal response and controlled release of copper oxide nanoparticles from multifunctional polymeric nanocarriers.

Multifunctional nanocarriers have attracted considerable interest in improving cancer treatment outcomes. Poly(lactide-co-glycolide) (PLGA) nanospheres encapsulating copper oxide nanoparticles (CuO-NPs) are characterized by antitumor activity and exhibit dual-modal contrast-enhancing capabilities. An in vitro evaluation demonstrates that this delivery system allows controlled and sustained release of CuO-NPs. To achieve localized release on demand, an external stimulation by laser irradiation is suggested. Furthermore, to enable simultaneous complementary photothermal therapy, polydopamine (PDA) coating for augmented laser absorption is proposed. To this aim, two formulations of CuO-NPs loaded nanospheres are prepared from PLGA polymers RG-504 H (H-PLGA) and RG-502 H (L-PLGA) as scaffolds for surface modification through in situ polymerization of dopamine and then PEGylation. The obtained CuO-NPs-based multifunctional nanocarriers are characterized, and photothermal effects are examined as a function of wavelength and time. The results show that 808 nm laser irradiation of the coated nanospheres yields maximal temperature elevation (T = 41°C) and stimulates copper release at a much faster rate compared to non-irradiated formulations. Laser-triggered CuO-NP release is mainly depended on the PLGA core, resulting in faster release with L-PLGA, which also yielded potent anti-tumor efficacy in head and neck cancer cell line (Cal-33). In conclusion, the suggested multifunctional nanoplatform offers the integrated benefits of diagnostic imaging and laser-induced drug release combined with thermal therapy.

Dose reduction in HDR brachytherapy of esophageal cancer using gold and gold alloy plaques: a Monte Carlo study.

In this work, the use of gold and gold alloy plaques is proposed for the first time, to reduce the dose to healthy organs in brachytherapy with Ir-192 sources. For dose simulations in tumour and healthy tissue, the MCNPX Monte Carlo code was used. The radiation source implemented in those simulations was benchmarked with well-known TG-43 criteria of dose rate constant, air-kerma strength, radial dose function, and 2D anisotropy function. For various arrangements of iridium sources and plaques of gold and gold alloy of various thicknesses, the dose distributions in an esophagus tumour and in surrounding healthy organs were simulated. The results showed that while the dose to the tumour is not much affected by the presence of gold plaques with a thickness of 3.5 mm in an optimized 192Ir sources' configuration, a relative reduction in average organ dose of 64%, 65%, 73%, 67%, and 35% was observed, for esophagus, thyroid, heart, stomach, and liver, respectively. Moreover, it was found that a gold plaque leads to smaller doses to healthy organs than a gold alloy plaque. It is concluded that gold plaques can be used to improve the treatment of esophageal cancer by HDR brachytherapy and to protect surrounding non-target organs.

A novel fusion-based deep learning model for sentiment analysis of COVID-19 tweets.

Undoubtedly, coronavirus (COVID-19) has caused one of the biggest challenges of all times. The ongoing COVID-19 pandemic has caused more than 150 million infected cases and one million deaths globally as of May 5, 2021. Understanding the sentiment of people expressed in their social media comments can help in monitoring, controlling, and ultimately eradicating the disease. This is a sensitive matter as the threat of infectious disease significantly affects the way people think and behave in various ways. In this study, we proposed a novel method based on the fusion of four deep learning and one classical supervised machine learning model for sentiment analysis of coronavirus-related tweets from eight countries. Also, we analyzed coronavirus-related searches using Google Trends to better understand the change in the sentiment pattern at different times and places. Our findings reveal that the coronavirus attracted the attention of people from different countries at different times in varying intensities. Also, the sentiment in their tweets is correlated to the news and events that occurred in their countries including the number of newly infected cases, number of recoveries and deaths. Moreover, common sentiment patterns can be observed in various countries during the spread of the virus. We believe that different social media platforms have great impact on raising people's awareness about the importance of this disease as well as promoting preventive measures among people in the community.

Laser-induced optothermal response of gold nanoparticles: From a physical viewpoint to cancer treatment application.

Gold nanoparticles (GNPs)-based photothermal therapy (PTT) is a promising minimally invasive thermal therapy for the treatment of focal malignancies. Although GNPs-based PTT has been known for over two decades and GNPs possess unique properties as therapeutic agents, the delivery of a safe and effective therapy is still an open question. This review aims at providing relevant and recent information on the usage of GNPs in combination with the laser to treat cancers, pointing out the practical aspects that bear on the therapy outcome. Emphasis is given to the assessment of the GNPs' properties and the physical mechanisms underlying the laser-induced heat generation in GNPs-loaded tissues. The main techniques available for temperature measurement and the current theoretical simulation approaches predicting the therapeutic outcome are reviewed. Topical challenges in delivering safe thermal dosage are also presented with the aim to discuss the state-of-the-art and the future perspective in the field of GNPs-mediated PTT.

A multimodal MR-compatible olfactometer with real-time controlling capability.

Design of an MR-compatible and computer-controlled odour stimuli system is essential in the studies of human olfactory function. Olfactometers are used to deliver odours to the subjects in an objective manner. We present a portable, computer-controlled eight channels olfactometer able to stimulate olfaction by employing liquid odorant stimuli. We used a high-pressure pump to generate medical grade airflow. After passing through solenoid valve-controlled odour reservoirs, odorant stimulus is conveyed to the nasal mask. The odour delivery delay of the device was measured using photo-ionisation detectors. To assess the application of the designed olfactometer, an fMRI experiment was done with 9 healthy subjects. Two odour stimuli (Vanillin and Rose) were presented to each subject in an alternating block design task of odour and non-odour conditions. The response time of each subject was gathered using the response box. Group analysis revealed a significant BOLD signal change in some regions of olfactory and trigeminal networks including the orbitofrontal cortex, insula, inferior frontal gyrus, hippocampus, cingulate gyrus and piriform cortex. The odour delivery delay measured by photo-ionisation detector was 190 ms, and the subjects' response showed 205 ms for the Vanillin and 243 ms for the Rose odour stimuli. Our portable MR-compatible olfactometer as a stimulation device is capable of creating adequate stimulation suitable for olfactory fMRI experiments.

Energy Choices in Alaska: Mining People's Perception and Attitudes from Geotagged Tweets.

Alaska is at the forefront of climate change and subject to salient challenges including energy consumption. It is important to understand Alaskans' perceptions and opinions about energy consumption to solve Alaska's domestic energy problems and creating a sustainable future. However, it is challenging to collect public opinions about energy consumption using conventional survey methods, which are often expensive, labor-intensive, and slow. This study utilizes information-rich Twitter data to investigate Alaskans' perceptions and opinions on various energy sources and in particular clean energy sources. Using the geotagged Twitter data collected in Alaska from 2014 to 2016, a lexicon-based sentiment analysis approach was first applied to analyze the polarity in the expressed opinions. Further, a novel fuzzy-based theory is employed to derive the sentiment of the opinion in each tweet. The results indicate that there is a valuable growth rate for a set of energy-related keywords, such as "sun", "power", and "nuclear". The rank of top 20 renewable energy-related keywords shows the word "Tidal" has the highest ranking followed by "solar panel". Moreover, the attention to various types of energy is increasing dramatically among Alaskans. Importantly, Alaskans' attitudes toward energy and renewable energy changed positively from 2014 to 2016, indicating that Alaskans' energy choices are more acceptive towards or even favor renewable energy in the future.

On the importance of modeling gold nanoparticles distribution in dose-enhanced radiotherapy.

Purpose: To investigate the effect of precise modeling for Monte Carlo simulations of gold nanoparticles (GNPs) dose-enhanced radiotherapy, two models characterized by their distribution of GNPs in a simulated macroscopic cubic tumor were introduced. The motivation was the widely documented tendency of GNPs to localize around the cell nucleus. Methods: The introduced models composed of 2.7×107 ellipsoid cells, each of them containing a centrally located nucleus as the target for dose evaluation. In the first model, the spheres of GNP are homogeneously distributed in the whole tumor volume, and in the latter, GNPs are localized in the cytoplasms surrounded the nuclei. Results: The results achieved through applying Monte Carlo radiation transports using the Mont Carlo N-Particle eXtended code (MCNPX) show an underestimation of nuclear dose enhancement caused by homogeneous model compared with that of heterogeneous distribution. By investigating various quantities, it was found that subcellular location of GNPs strongly governs the sensitivity of dose enhancement to the number and concentration of GNPs targeted in the tumor. Other obvious differences are revealed by studying the dose enhancement curves in depth of the tumor. While the heterogeneous model predicts an approximately constant dose enhancement in depth for primary photon energies of 50 keV and more, the homogeneous model estimates an energy-dependent increase of about 11 to 30%. Conclusion: It can be concluded that defining a model in accordance with the experimental observations can effectively account for accurate prediction of macroscopic dose enhancement in the target of interest.

Gamma irradiation of ocular melanoma and lymphoma cells in the presence of gold nanoparticles: in vitro study.

The aim of this work was to determine whether conjugation of cultivated choroidal melanoma and Burkitt's lymphoma cells with gold nanoparticles (GNPs) is beneficial for these series of ocular cancer patients. GNPs are radiosensitizers and can sensitize tumors to radiotherapy.This application has been examined in several tumor types, but not in choroidal melanoma. This study shows the results of in vitro study on the choroidal melanoma and also Burkitt's lymphoma cells in the presence of GNPs during continuous gamma irradiation. Cytotoxicity of GNPs were assessed for five different concentrations then cultured melanoma and Burkitt's lymphoma cells were irradiated with a Gamma source in the presence and absence of NPs. Incubation of melanoma cells with GNP concentrations below 100 µg/ml, accompanied by gamma irradiation, increased cell death (P value = 0.016) . In the absence of irradiation, GNPs at these concentrations did not affect cultured melanoma cell metabolism. Reduced cell viability resulted from a significant increase in absorbed energy by the tumor. Moreover, GNP concentrations higher than 200 µg/ml induced cytotoxicity in melanoma cells. Cytotoxicity assay in GNPs-loaded Burkitt's lymphoma cells showed a slight decrease in cell viability at 50 µg/ml and clear cytotoxicity at concentrations higher than 100 µg/ml (P value = 0.035). Concentration and proper injection doses of GNPs in sensitive tissues such as the human eye are important variables yet to be determined.This is the first report of choroidal melanoma dosimetry performed in the presence of GNPs and provides valuable insights into future therapeutic approaches. Further in vitro study with more different sizes and concentrations is needed to determine the optimum size and concentration before any clinical research in this regard.

Ocular brachytherapy dosimetry for 103Pd and 125I in the presence of gold nanoparticles: a Monte Carlo study.

The aim of the present Monte Carlo study is to evaluate the variation of energy deposition in healthy tissues in the human eye which is irradiated by brachytherapy sources in comparison with the resultant dose increase in the gold nanoparticle (GNP)-loaded choroidal melanoma. The effects of these nanoparticles on normal tissues are compared between 103Pd and 125I as two ophthalmic brachytherapy sources. Dose distribution in the tumor and healthy tissues has been taken into account for both brachytherapy sources. Also, in certain points of the eye, the ratio of the absorbed dose by the normal tissue in the presence of GNPs to the absorbed dose by the same point in the absence of GNPs has been calculated. In addition, differences of the absorbed dose in the tumor observed in the comparison of simple water phantom and actual simulated human eye in presence of GNPs are also a matter of interest that have been considered in the present work. The difference between the eye globe and the water phantom is more obvious for 125I than that of the 103Pd when the ophthalmic dosimetry is done in the presence of GNPs. Whenever these nanoparticles are utilized in enhancing the absorbed dose by the tumor, the use of 125I brachytherapy source will greatly amplify the amount of dose enhancement factor (DEF) in the tumor site without inflicting much dam-age to healthy organs, when compared to the 103Pd source. For instance, in the concentration of 30 mg GNPs, the difference amongst the calculated DEF for 125I between these phantoms is 5.3%, while it is 2.45% for 103Pd. Furthermore, in Monte Carlo studies of eye brachytherapy, more precise definition of the eye phantom instead of a water phantom will become increasingly important when we use 125I as opposed to 103Pd.