Journal of Biomedical Physics and Engineering最新文献

Background: Photothermal therapy (PTT) is one of the effective and non-invasive strategies which hold great promise for improving the treatment of cancer cells. PTT is based on activating a photosensitizer by infrared light irradiation and producing heat and reactive species and apoptosis in the tumor area.

Objective: The aim of this study was to investigate the effect of photothermal/chemotherapy on melanoma cancer cells using poly (2-amino phenol)/gold (P2AO/AuNPs) and doxorubicin (DOX).

Material and methods: In this experimental study, nanoparticles of P2AO/AuNPs were synthesized, and their mixture with DOX was applied as a photosensitizer for photothermal/chemotherapy of a C540 (B16-F10) melanoma cell line.

Results: P2AO/AuNPs generated heat and cytotoxic responsive oxygen species (ROS) upon 808-nm light irradiation with simultaneous intensifying DOX therapeutic effect under domination of synergism effects between light irradiation, P2AO/AuNPs, and doxorubicin. Cell treatment with both P2AO/AuNPs and DOX resulted in a considerable increase in necroptotic cells to 61% with a significant decrease in the living cells (39%).

Conclusion: P2AO/AuNPs provided a platform for light absorption and intensifying DOX therapeutic effect. This study approved the applicability of a new photothermal/chemotherapy by domination of synergistic effects attained by combination of laser light, P2AO, AuNPs, and DOX.

Background: T₁ thermometry is considered a straight method for the safety monitoring of patients with deep brain stimulation (DBS) electrodes against radiofrequency-induced heating during Magnetic Resonance Imaging (MRI), requiring different sequences and methods.

Objective: This study aimed to compare two T₁ thermometry methods and two low specific absorption rate (SAR) imaging sequences in terms of the output image quality.

Material and methods: In this experimental study, a gel phantom was prepared, resembling the brain tissue properties with a copper wire inside. Two types of rapid gradient echo sequences, namely radiofrequency-spoiled and balanced steady-state free precession (bSSFP) sequences, were used. T₁ thermometry was performed by either T₁-weighted images with a high SAR sequence to increase heating around the wire or T₁ mapping methods.

Results: The balanced steady-state free precession (bSSFP) sequence provided higher image quality in terms of spatial resolution (1×1×1.5 mm³ compared with 1×1×3 mm³) at a shorter acquisition time. The susceptibility artifact was also less pronounced for the bSSFP sequence compared with the radiofrequency-spoiled sequence. A temperature increase, of up to 8 ℃, was estimated using a high SAR sequence. The estimated change in temperature was reduced when using the T₁ mapping method.

Conclusion: Heating induced during MRI of implanted electrodes could be estimated using high-resolution T₁ maps obtained from inversion recovery bSSFP sequence. Such a method gives a direct estimation of heating during the imaging sequence, which is highly desirable for safe MRI of DBS patients.

In diagnostic radiology, entrance surface air kerma (ESAK) is one of the patient radiation dose quantities, and the effective dose is used as an estimator of possible risk for radiation exposure level. Calculation of the ESAK and effective dose requires both X-ray machine parameters and patient exposure parameters. Due to the high performance of smartphones and the increase in mobile applications, this study aimed to develop a mobile application to estimate the ESAK and effective dose in general radiography. The ESAK calculator was then developed using Android studio software, which is a standalone application operating on Android operating system version 5.0 or higher. X-ray machine parameters are initially required for calculating X-ray output. For the ESAK and effective dose calculation, exposure parameters for each examination are needed. The results showed that the average score of satisfaction was 4.64±0.13, which was very satisfactory. In conclusion, the ESAK calculator could be used for estimating ESAK and effective dose for individual radiographic examination.

Background: Coronary heart disease the most prevalent form of cardiovascular disease, results from the blockage of blood flow through arteries. The Myocardial Perfusion Scan (MPS) is considered a non-invasive method to assess the heart condition and provides valuable information, such as End Diastolic Volume (EDV), End Systolic Volume (ESV), Ejection Fraction (EF), Lung to Heart Ratio (LHR), and Transient Ischemic Dilatation (TID).

Objective: This study aimed to investigate changes in gated heart scan parameters to diagnose patients, who are candidates for heart surgery.

Material and methods: In this descriptive cross-sectional study, 40 patients who are candidates for heart surgery were enrolled to evaluate the relation between the parameters of the gated heart scan and the amount of ischemic area of the heart. After scanning the patients, TID, ESV, LHR, and EF and also the movements of the heart walls are examined and analyzed in these patients.

Results: According to the results of the one-sample t-test showing a significant difference between the parameters, the results were within the normal range (P-value<0.0001). Additionally, all patients showed changes in cardiac output and wall movement issues.

Conclusion: The evaluation of Myocardial Perfusion Scan (MPS) and gated heart scan parameters can provide an effective method for diagnosing patients who may require heart surgery.

Background: Acquiring new knowledge necessitates alterations at the synaptic level within the brain. Glutamate, a pivotal neurotransmitter, plays a critical role in these processes, particularly in learning and memory formation. Although previous research has explored glutamate's involvement in cognitive functions, a comprehensive understanding of its real-time dynamics remains elusive during memory tasks.

Objective: This study aimed to investigate glutamate modulation during memory tasks in the right Dorsolateral Prefrontal Cortex (DLPFC) and parieto-occipital regions using functional Magnetic Resonance Spectroscopy (fMRS).

Material and methods: This experimental research applied fMRS acquisition concurrently with a modified Sternberg's verbal working memory task for fourteen healthy right-handed participants (5 females, mean age=30.64±4.49). The glutamate/total-creatine (Glu/tCr) ratio was quantified by LCModel in the DLPFC and parieto-occipital voxels while applying the tissue corrections.

Results: The significantly higher Glu/tCr modulation was observed during the task with a trend of increased modulation with memory load in both the DLPFC (19.9% higher, P-value=0.018) and parieto-occipital (33% higher, P-value=0.046) regions compared to the rest.

Conclusion: Our pioneering fMRS study has yielded groundbreaking insights into brain functions during S-term Memory (STM) and learning. This research provides valuable methodological advancements for investigating the metabolic functions of both healthy and disordered brains. Based on the findings, cognitive demands directly correlate with glutamate levels, highlighting the neurochemical underpinnings of cognitive processing. Additionally, the obtained results potentially challenge the traditional left-hemisphere-centric model of verbal working memory, leading to the deep vision of hemispheric contributions to cognitive functions.

During the early days of the COVID-19 pandemic, low dose radiation therapy (LDRT) was proposed as a potentially effective treatment method. To minimize potential toxicity, the initial treatment approach involved a few mGy of adapting radiation followed by a single 250 mGy whole lung challenging dose. However, antiviral drugs were also introduced as a promising treatment option, which were thought to have the potential to revolutionize the management of the crisis. Despite early warnings, many physicians did not fully consider the key point that, in contrast with LDRT, antiviral drug treatments can result in strong selective pressure on the virus. This can lead to the emergence of new SARS-CoV-2 variants, a phenomenon that can have serious global consequences. After more than two years, the truth has been revealed the WHO Guideline Development Group has advised against the use of remdesivir, a widely used antiviral medication, for COVID-19. Meanwhile, a growing body of evidence suggests that LDRT can be a promising, low-risk approach for avoiding or delaying invasive respiratory support in COVID-19 patients. Although there is substantial supporting documentation, more high-quality, controlled, and randomized double-blind clinical trials are needed to further investigate the efficacy and potential therapeutic mechanisms of LDRT for COVID-19.

Background: Application of the nanomaterials to preparing X-ray shields and successfully treating multiresistant microorganisms has attracted great attention in modern life.

Objective: This study aimed to prepare flexible silicone-based matrices containing Bi₂O₃, PbO, or Bi₂O₃/PbO nanoparticles and select a cost-effective, cytocompatible, and antibacterial/antifungal X-ray shield in clinical radiography.

Material and methods: In this experimental study, we prepared the nanoparticles by the modified biosynthesis method and fabricated the X-ray shields containing 20 wt% of the nanoparticles. The X-ray attenuation percentage and Half Value Layer (HVL) of the shields were investigated for the photon energies in the range of 40-100 kVp in clinical radiography. The antibacterial/antifungal activities of the shields were evaluated using a colony count method for the gram-negative (Escherichia coli), and gram-positive (Enterococcus faecalis) bacteria, and Candida albicans fungus. The shield toxicity was investigated on A549 cells.

Results: The highest X-ray attenuation percentage and the lowest HVL were obtained using the shield containing Bi₂O₃ nanoparticles. Although all shields displayed antimicrobial activity, the shield containing Bi₂O₃/PbO nanoparticles showed the most effective reduction in the colony counts. Both X-ray shields containing nano Bi₂O₃ and Bi₂O₃/PbO demonstrated high cytocompatibility on A549 cells at a concentration as high as 500 µg/ml. The shield with PbO nanoparticles was also cytocompatible at a concentration of 50 µg/ml.

Conclusion: The best X-ray attenuation performance is attributed to the silicone-based matrix with nano Bi₂O₃; however, the flexible shield with Bi₂O₃/PbO nanoparticles can be cost-effective and cytocompatible with the best antibacterial/antifungal properties.

Background: Non-specific chronic low back pain (CLBP) is a common painful condition and is responsible for different physical disorders. Despite alternative therapies, patients still suffer from persistent pain. Repetitive transcranial magnetic stimulation (rTMS) has provided much evidence of pain reduction, but results have not been examined deeply in CLBP symptoms.

Objective: The analgesic effect of rTMS in non-specific CLBP patients was evaluated by the amplitude of low-frequency fluctuation (ALFF) analysis in resting-state fMRI.

Material and methods: In this experimental study, fifteen non-specific CLBP participants (46.87±10.89 years) received 20 Hz rTMS over the motor cortex. The pain intensity and brain functional scan were obtained during pre and post-stimulation for all participants. The ALFF maps of the brain in two scan sessions were identified and the percentage of pain reduction (PPR%) was determined using paired t-test. Also, correlation analysis was used to find a relationship between ALFFs and pain intensity.

Results: Pain intensity was significantly reduced after induced-rTMS in non-specific CLBP (36.22%±13.28, P<0.05). Positive correlation was found between ALFF in the insula (INS) and pain intensity (r_pre-rTMS=0.59, r_post-rTMS=0.58) while ALFF in medial prefrontal cortex (mPFC) and pain intensity had negatively correlated (r_pre-rTMS=-0.54, r_post-rTMS=-0.56) (P<0.05). ALFF increased in mPFC while INS, thalamus (THA), and supplementary motor area (SMA) showed decremental ALFF followed by rTMS.

Conclusion: This study demonstrated that ALFF in INS, THA, mPFC, and SMA is associated with CLBP symptoms and analgesic effects of rTMS. ALFF potentially seems to be a proper objective neuroimaging parameter to link spontaneous brain activity with pain intensity in non-specific CLBP patients.