Thermomechanical Modeling of Laser Ablation Therapy of Tumors: Sensitivity Analysis and Optimization of Influential Variables.

In cancer treatment, laser ablation is a promising technique used to induce localized thermal damage. Different variables influence the temperature distribution in the tissue and the resulting therapy efficacy; thus, the optimal therapy settings are required for obtaining the desired clinical outcome. In this work, thermomechanical modeling of contactless laser ablation was implemented to analyze the sensitivity of independent variables on the optimal treatment conditions. The Finite Element Method was utilized to solve the governing equations, i.e., the bioheat, mechanical deformation, and the Navier-Stokes equations. Validation of the model was performed by comparing experimental and simulated temperatures, which indicated high accuracy for estimating temperature. In particular, the results showed that the model can estimate temperature with a good correlation factor (R = 0.98) and low Mean Absolute Error (3.9 °C). A sensitivity analysis based on laser irradiation time, power, beam distribution, and the blood vessel depth on temperature distribution and fraction of necrotic tissue was performed. An optimization process was performed based on the most significant variables, i.e., laser irradiation time and power. This resulted in an indication of the optimal therapy settings for achieving maximum procedure efficiency i.e., the required fraction of necrotic tissue within the target volume, constituted by tumor and safety margins around it.

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.

Sericin alleviates restraint stress induced depressive- and anxiety-like behaviors via modulation of oxidative stress, neuroinflammation and apoptosis in the prefrontal cortex and hippocampus.

This study was aimed to examine the effects of sericin administration on restraint stress induced anxiety- and depressive-like behaviors, oxidative stress, inflammation and apoptosis in the prefrontal cortex (PFC) and hippocampus (HIP) of mice. Animals were subjected to chronic restraint stress (3 h/day for 21 days) to induce a depressive-like model. Sericin was administered at different doses (100, 150, and 200 mg/kg/day, gavage for 21 days) along with immobilization. Elevated plus maze (EPM) and open field test (OFT) were performed to assess anxiety; while, the forced swim test (FST) and tail suspension test (TST) were implemented to evaluate depressive-like behaviors. Mitochondrial membrane potential (MMP), and markers of oxidative stress, neuroinflammation, and apoptosis were evaluated in the PFC and HIP regions. Moreover, serum levels of corticosterone were measured. Results showed that sericin increased number of central entries in OFT and prolonged time spent in open arms of EPM apparatus, while it reduced immobility time in TST and FST. Moreover, sericin treatments decreased oxygen species (ROS) and lipid peroxidation levels, restored MMP, and enhanced total antioxidant capacity (TAC) and enzyme activity of GPx and SOD in both brain regions. Furthermore, sericin reduced serum corticosterone concentration and suppressed neuroinflammatory response in the HIP and PFC, shown by decreased NF-κB, TNF-α, and IL-1ß protein levels. Finally, sericin inhibited mitochondrial-dependent apoptosis pathway through down-regulation of Bax, cytochrome c, caspase-9 and -3, and up-regulation of Bcl-2 protein. These findings provide evidence for the protective effect of sericin therapy against psychopathological and behavioral changes induced by restraint stress.

Identification and applications of neuroactive silk proteins: a narrative review.

In traditional medicine, natural silk is regarded as a cognitive enhancer and a cure for ameliorating the symptoms of heart disease, atherosclerosis, and metabolic disorders. In this review, general characteristics of both silk proteins, fibroin and sericin, extracted from silkworm Bombyx mori and their potential use in the neuronal disorders was discussed. Evidence shows that silk proteins exhibit neuroprotective effects in models of neurotoxicity. The antioxidant, neuroprotective, and acetylcholinesterase inhibitory mechanisms of silk proteins could prove promising in the treatment of neurodegenerative diseases. Owing to their excellent neurocompatibility and physicochemical properties, silk proteins have been used as scaffolds and drug delivery materials in the neuronal tissue engineering. These data support the potential of silk proteins as an effective complementary agent for central and peripheral neurological disorders.