Frequency dependence of ultrasonic effects on the kinetics of hen egg white lysozyme fibrillation

Our study aimed to investigate the effects of ultrasound on the fibrillation kinetics of HEWL (hen egg white lysozyme) and its physicochemical properties. Ultrasound, a mechanical wave, can induce conformational changes in proteins. To achieve this, we developed an ultrasound exposure system and used various biophysical techniques, including ThT fluorescence spectroscopy, ATR-FTIR, Far-UV CD spectrophotometry, Fluorescence microscopy, UV-spectroscopy, and seeding experiments. Our results revealed that higher frequencies significantly accelerated the fibrillation of lysozyme by unfolding the native protein and promoting the fibrillation process, thereby reducing the lag time. We observed a change in the secondary structure of the sonicated protein change to the β-structure, but there was no difference in the Tm of native and sonicated proteins. Furthermore, we found that higher ultrasound frequencies had a greater seeding effect. We propose that the effect of frequency can be explained by the impact of the Reynolds number, and for the Megahertz frequency range, we are almost at the transition regime of turbulence. Our results suggest that laminar flows may not induce any significant change in the fibrillation kinetics, while turbulent flows may affect the process.

Alternating electric fields can improve chemotherapy treatment efficacy in blood cancer cell U937 (non-adherent cells)

BACKGROUND

Recent achievements in cancer therapy are the use of alternating electrical fields at intermediate frequencies (100-300 kHz) and low intensities (1-3 V/cm), which specifically target cell proliferation while affecting different cellular activities depending on the frequency used.

METHODS

In this article, we examine the effect of electric fields on spherical suspended cells and propose the combination of Daunorubicin, a chemotherapy agent widely used in the treatment of acute myeloid leukemia, with electric field exposure. U937 cells were subjected to an electric field with a frequency of 200 kHz and an intensity of 0.75 V/cm, or to a combination of Daunorubicin and electric field exposure, resulting in a significant reduction in cell proliferation. Furthermore, the application of an electric field to U937 cells increased Daunorubicin uptake.

RESULTS

Apoptosis and DNA damage were induced by the electric field or in conjunction with Daunorubicin. Notably, normal cells exposed to an electric field did not show significant damage, indicating a selective effect on dividing cancer cells (U937). Moreover, the electric field affects the U937 cell line either alone or in combination with Daunorubicin. This effect may be due to increased membrane permeability.

CONCLUSIONS

Our findings suggest that the use of electric fields at intermediate frequencies and low intensities, either alone or in combination with Daunorubicin, has potential as a selective anti-cancer therapy for dividing cancer cells, particularly in the treatment of acute myeloid leukemia. Further research is needed to fully understand the underlying mechanisms and to optimize the use of this therapy.

P53 status, and G2/M cell cycle arrest, are determining factors in cell-death induction mediated by ELF-EMF in glioblastoma

The average survival of patients with glioblastoma is 12-15 months. Therefore, finding a new treatment method is important, especially in cases that show resistance to treatment. Extremely low-frequency electromagnetic fields (ELF-EMF) have characteristics and capabilities that can be proposed as a new cancer treatment method with low side effects. This research examines the antitumor effect of ELF-EMF on U87 and U251 glioblastoma cell lines. Flowcytometry determined the viability/apoptosis and distribution of cells in different phases of the cell cycle. The size of cells was assessed by TEM. Important cell cycle regulation genes mRNA expression levels were investigated by real-time PCR. ELF-EMF induced apoptosis in U87cells much more than U251 (15% against 2.43%) and increased G2/M cell population in U87 (2.56%, p value < 0.05), and S phase in U251 (2.4%) (data are normalized to their sham exposure). The size of U87 cells increased significantly after ELF-EMF exposure (overexpressing P53 in U251 cells increased the apoptosis induction by ELF-EMF). The expression level of P53, P21, and MDM2 increased and CCNB1 decreased in U87. Among the studied genes, MCM6 expression decreased in U251. Increasing expression of P53, P21 and decreasing CCNB1, induction of cell G2/M cycle arrest, and consequently increase in the cell size can be suggested as one of the main mechanisms of apoptosis induction by ELF-EMF; furthermore, our results demonstrate the possible footprint of P53 in the apoptosis induction by ELF-EMF, as U87 carry the wild type of P53 and U251 has the mutated form of this gene.

Chemical Modification of the Amino Groups of Human Insulin: Investigating Structural Properties and Amorphous Aggregation of Acetylated Species

The efficacy of human recombinant insulin can be affected by its aggregation. Effects of acetylation were observed on insulin structure, stability, and aggregation at 37 and 50 °C and pH of 5.0 and 7.4 with the use of spectroscopy, circular dichroism (CD), dynamic light scattering (DLS), and atomic force microscopy (AFM). Raman and FTIR results were indicative of structural changes in AC-INS, and CD analyses showed a slight increase in β-sheet content in AC-INS. Melting temperature (T_m) measurements indicated an overall more stable structure and spectroscopic assessment showed a more compact one. Formation of amorphous aggregates was followed over time and kinetics parameters showed a longer nucleation phase (higher t* amount) and lower aggregates amount (lower A_lim) for acetylated insulin (AC-INS) compared to native (N-INS) in all tested conditions. The results of amyloid-specific probes approved the formation of amorphous aggregates. Size particle and microscopic analysis suggested that AC-INS was less prone to form aggregates, which were smaller if formed. In conclusion, this study has demonstrated that controlled acetylation of insulin may lead to its higher stability and lower propensity toward amorphous aggregation and has provided insight into the result of this type of post-translational protein modification.

Cross-talk between non-ionizing electromagnetic fields and metastasis; EMT and hybrid E/M may explain the anticancer role of EMFs

Recent studies have shown that non-ionizing electromagnetic fields (NIEMFs) in a specific frequency, intensity, and exposure time can have anti-cancer effects on various cancer cells; however, the underlying precise mechanism of action is not transparent. Most cancer deaths are due to metastasis. This important phenomenon plays an inevitable role in different steps of cancer including progression and development. It has different stages including invasion, intravasation, migration, extravasation, and homing. Epithelial-mesenchymal transition (EMT), as well as hybrid E/M state, are biological processes, that involve both natural embryogenesis and tissue regeneration, and abnormal conditions including organ fibrosis or metastasis. In this context, some evidence reveals possible footprints of the important EMT-related pathways which may be affected in different EMFs treatments. In this article, critical EMT molecules and/or pathways which can be potentially affected by EMFs (e.g., VEGFR, ROS, P53, PI3K/AKT, MAPK, Cyclin B1, and NF-кB) are discussed to shed light on the mechanism of EMFs anti-cancer effect.

Targeting myeloid-derived suppressor cells in combination with tumor cell vaccination predicts anti-tumor immunity and breast cancer dormancy: an in silico experiment

Among the different breast cancer subsets, triple-negative breast cancer (TNBC) has the worst prognosis and limited options for targeted therapies. Immunotherapies are emerging as novel treatment opportunities for TNBC. However, the surging immune response elicited by immunotherapies to eradicate cancer cells can select resistant cancer cells, which may result in immune escape and tumor evolution and progression. Alternatively, maintaining the equilibrium phase of the immune response may be advantageous for keeping a long-term immune response in the presence of a small-size residual tumor. Myeloid-derived suppressor cells (MDSCs) are activated, expanded, and recruited to the tumor microenvironment by tumor-derived signals and can shape a pro-tumorigenic micro-environment by suppressing the innate and adaptive anti-tumor immune responses. We recently proposed a model describing immune-mediated breast cancer dormancy instigated by a vaccine consisting of dormant, immunogenic breast cancer cells derived from the murine 4T1 TNBC-like cell line. Strikingly, these 4T1-derived dormant cells recruited fewer MDSCs compared to aggressive 4T1 cells. Recent experimental studies demonstrated that inactivating MDSCs has a profound impact on reconstituting immune surveillance against the tumor. Here, we developed a deterministic mathematical model for simulating MDSCs depletion from mice bearing aggressive 4T1 tumors resulting in immunomodulation. Our computational simulations indicate that a vaccination strategy with a small number of tumor cells in combination with MDSC depletion can elicit an effective immune response suppressing the growth of a subsequent challenge with aggressive tumor cells, resulting in sustained tumor dormancy. The results predict a novel therapeutic opportunity based on the induction of effective anti-tumor immunity and tumor dormancy.

Electromagnetic field therapy in cardiovascular diseases: A review of patents, clinically effective devices, and mechanism of therapeutic effects

In recent years, electromagnetic field (EMF) therapy has gathered much attention for its protective effects on cardiovascular functions. From reviewing the literature, it is evident that exposure to specific EMF spectrums, such as static- and extremely low frequency (ELF)- EMFs, by EMF-generating devices can be considered as a safe method for therapeutic means in various cardiovascular diseases, including heart failure, cardiac arrhythmias, and hypertension. This review article will describe registered patents and non-invasive clinically effective devices that generate EMF to target various cardiovascular diseases based on their mechanism of therapeutic effects.

Assignment of structural domains in proteins using diffusion kernels on graphs

Though proposing algorithmic approaches for protein domain decomposition has been of high interest, the inherent ambiguity to the problem makes it still an active area of research. Besides, accurate automated methods are in high demand as the number of solved structures for complex proteins is on the rise. While majority of the previous efforts for decomposition of 3D structures are centered on the developing clustering algorithms, employing enhanced measures of proximity between the amino acids has remained rather uncharted. If there exists a kernel function that in its reproducing kernel Hilbert space, structural domains of proteins become well separated, then protein structures can be parsed into domains without the need to use a complex clustering algorithm. Inspired by this idea, we developed a protein domain decomposition method based on diffusion kernels on protein graphs. We examined all combinations of four graph node kernels and two clustering algorithms to investigate their capability to decompose protein structures. The proposed method is tested on five of the most commonly used benchmark datasets for protein domain assignment plus a comprehensive non-redundant dataset. The results show a competitive performance of the method utilizing one of the diffusion kernels compared to four of the best automatic methods. Our method is also able to offer alternative partitionings for the same structure which is in line with the subjective definition of protein domain. With a competitive accuracy and balanced performance for the simple and complex structures despite relying on a relatively naive criterion to choose optimal decomposition, the proposed method revealed that diffusion kernels on graphs in particular, and kernel functions in general are promising measures to facilitate parsing proteins into domains and performing different structural analysis on proteins. The size and interconnectedness of the protein graphs make them promising targets for diffusion kernels as measures of affinity between amino acids. The versatility of our method allows the implementation of future kernels with higher performance. The source code of the proposed method is accessible at https://github.com/taherimo/kludo . Also, the proposed method is available as a web application from https://cbph.ir/tools/kludo .

An overview of the biological effects of extremely low frequency electromagnetic fields combined with ionizing radiation

By growing the electrical power networks and electronic devices, electromagnetic fields (EMF) have become an inseparable part of the modern world. Considering the inevitable exposure to a various range of EMFs, especially at extremely low frequencies (ELF-EMF), investigating the biological effects of ELF-EMFs on biological systems became a global issue. The possible adverse consequences of these exposures were studied, along with their potential therapeutic capabilities. Also, their biological impacts in combination with other chemical and physical agents, specifically ionizing radiation (IR), as a co-carcinogen or as adjuvant therapy in combination with radiotherapy were explored. Here, we review the results of several in-vitro and in-vivo studies and discuss some proposed possible mechanisms of ELF-EMFs' actions in combination with IR. The results of these experiments could be fruitful to develop more precise safety standards for environmental ELF-EMFs exposures. Furthermore, it could evaluate the therapeutic capacities of ELF-EMFs alone or as an improver of radiotherapy.

Sex Differences in Healthy Eating: Investigating the Moderating Effect of Self-Efficacy

OBJECTIVES

This study aimed to evaluate sex differences in dietary habits and the moderating effect of self-efficacy on the adoption of a healthy diet.

DESIGN

Cross-sectional study.

SETTING

The healthy population of Tehran, Iran.

PARTICIPANTS

A total of 262 participants from the general population with normal health status.

MAIN OUTCOME MEASURE

The adoption of a healthy diet was based on the Healthy Eating Index-2015 (HEI-2015) scores and the moderating effect of self-efficacy on eating behaviors.

ANALYSIS

Logistic regression analysis and multiple linear regression (moderation) analysis were conducted using PROCESS macro (version 3.5).

RESULTS

The sex-based analysis revealed that females were more likely to adopt a healthy diet vs males (adjusted odds ratio, 1.85; 95% confidence interval, 1.02-3.35). The moderation analysis showed that eating behavior self-efficacy significantly moderated the relationship between sex differences and HEI-2015 scores (ΔR² = 0.01; P = 0.033). Males with low self-efficacy scores had the highest difference in HEI-2015 with females with low self-efficacy scores, whereas the difference in HEI-2015 was very small in males and females with high self-efficacy scores.

CONCLUSIONS AND IMPLICATIONS

Eating behavior self-efficacy had a significantly decreasing moderating effect on sex differences in the adoption of a healthy diet. Future research needs to clarify the impact of eating`` behavior self-efficacy in the adoption of a healthy diet, particularly in males, and to confirm the study's findings.

Cellular stress response to extremely low-frequency electromagnetic fields (ELF-EMF): An explanation for controversial effects of ELF-EMF on apoptosis

Impaired apoptosis is one of the hallmarks of cancer, and almost all of the non‐surgical approaches of eradicating tumour cells somehow promote induction of apoptosis. Indeed, numerous studies have stated that non‐ionizing non‐thermal extremely low‐frequency magnetic fields (ELF‐MF) can modulate the induction of apoptosis in exposed cells; however, much controversy exists in observations. When cells are exposed to ELF‐EMF alone, very low or no statistically significant changes in apoptosis are observed. Contrarily, exposure to ELF‐EMF in the presence of a co‐stressor, including a chemotherapeutic agent or ionizing radiation, can either potentiate or inhibit apoptotic effects of the co‐stressor. In our idea, the main point neglected in interpreting these discrepancies is “the cellular stress responses” of cells following ELF‐EMF exposure and its interplay with apoptosis. The main purpose of the current review was to outline the triangle of ELF‐EMF, the cellular stress response of cells and apoptosis and to interpret and unify discrepancies in results based on it. Therefore, initially, we will describe studies performed on identifying the effect of ELF‐EMF on induction/inhibition of apoptosis and enumerate proposed pathways through which ELF‐EMF exposure may affect apoptosis; then, we will explain cellular stress response and cues for its induction in response to ELF‐EMF exposure; and finally, we will explain why such controversies have been observed by different investigators.

Conifer: clonal tree inference for tumor heterogeneity with single-cell and bulk sequencing data

BACKGROUND

Genetic heterogeneity of a cancer tumor that develops during clonal evolution is one of the reasons for cancer treatment failure, by increasing the chance of drug resistance. Clones are cell populations with different genotypes, resulting from differences in somatic mutations that occur and accumulate during cancer development. An appropriate approach for identifying clones is determining the variant allele frequency of mutations that occurred in the tumor. Although bulk sequencing data can be used to provide that information, the frequencies are not informative enough for identifying different clones with the same prevalence and their evolutionary relationships. On the other hand, single-cell sequencing data provides valuable information about branching events in the evolution of a cancerous tumor. However, the temporal order of mutations may be determined with ambiguities using only single-cell data, while variant allele frequencies from bulk sequencing data can provide beneficial information for inferring the temporal order of mutations with fewer ambiguities.

RESULT

In this study, a new method called Conifer (ClONal tree Inference For hEterogeneity of tumoR) is proposed which combines aggregated variant allele frequency from bulk sequencing data with branching event information from single-cell sequencing data to more accurately identify clones and their evolutionary relationships. It is proven that the accuracy of clone identification and clonal tree inference is increased by using Conifer compared to other existing methods on various sets of simulated data. In addition, it is discussed that the evolutionary tree provided by Conifer on real cancer data sets is highly consistent with information in both bulk and single-cell data.

CONCLUSIONS

In this study, we have provided an accurate and robust method to identify clones of tumor heterogeneity and their evolutionary history by combining single-cell and bulk sequencing data.

Necroptosis triggered by ROS accumulation and Ca2+ overload, partly explains the inflammatory responses and anti-cancer effects associated with 1Hz, 100 mT ELF-MF in vivo

Whereas the anti-neoplastic activity of extremely low frequency magnetic fields (ELF-EMF) is well-documented in literature, little is known about its underlying anti-cancer mechanisms and induced types of cell death. Here, for the first time, we reported induction of necroptosis, a specific type of programed necrotic cell death, in MC4-L2 breast cancer cell lines following a 2 h/day exposure to a 100 Hz, 1 mT ELF-EMF for five days. For in vivo assessment, inbred BALB/c mice bearing established MC-4L2 tumors were exposed to 100 mT, 1 Hz ELF-EMF 2 h daily for a period of 28-day, following which tumors were dissected and fixed for evaluation of tumor biomarkers expression and types of cell death induced using TUNEL assay, Immunohistochemistry and H&E staining. Peripheral blood samples were also collected for assessing pro-inflammatory cytokine profile following exposure. An exaggerated proinflammatory response evident form enhancement of IFN-γ (4.8 ± 0.24 folds) and TNF-α (3.1 ± 0.19 folds) and number of tumors infiltrating lymphocytes (TILs), specially CD8⁺ T_h cells (~20 folds), proposed occurrence of necroptosis in vivo. Meanwhile, exposure could effectively suppress tumor growth and expression of Ki-67, CD31, VEGFR2 and MMP-9. In vitro studies on ELF-EMF exposed MC-4L2 cells demonstrated a meaningful increase in phosphorylation of RIPK1/RIPK3/MLKL proteins and cleavage of caspase-9/caspase-3, confirming occurrence of both necroptosis and apoptosis. Complementary in vitro studies by treating ELF-EMF exposed MC-4L2 cells with verapamil (a calcium channel inhibitor), N-acetyl cysteine (a ROS scavenger) or calcium chloride confirmed the role of elevated intracellular calcium and ROS levels in ELF-EMF induced necroptosis.

The Role of Peer Influence on Oral Health Knowledge and Behaviors among Adolescents

Although many researchers, in different social sciences fields, are being attracted to the new potential promotional phenomenon, the influence of peer connections, the literature in dental public health is very poor. Objective: This article investigates the role of peer influence on individuals’ oral health knowledge and behavior among adolescents. Methods: The purpose of the study was to explore the correlation between secondary school students’ oral health u and knowledge within friendship groups. A valid and reliable questionnaire was developed. A total of 421 students (228 boys and 193 girls) aged between 12-13 years old participated in the study. Ordinal regression analysis was used to identify the correlation between an individual’s oral health knowledge and his/her friends. Results: The results demonstrated a strong relationship between students’ oral health behaviors and their peer connections within their friendship groups at school. Specifically, the tooth brushing frequency of a student had a strong correlation with the similar behavior of his/her friends. Also, investigation of the role of the second level connections (friends of one’s friend with no direct connection) showed a significant correlation in brushing behavior. However, the results revealed no strong correlation of oral health knowledge among friends within their social network. Conclusion: This paper highlighted the importance of the role of peer influence on oral health behavior. Understanding the relationship between oral health behavior and social network would help policymakers for more cost-effective oral health promotion programs among adolescents.

Designing a magnetic inductive micro-electrode for virus monitoring: modelling and feasibility for hepatitis B virus

A simple model is designed for an inductive immunosensor in which the magnetic particles are attached to the bioreceptors to form a sandwich on the surface of an inductor. The inductor consists of a coil covered on a silicon oxide wafer. The coil comprises 250 turns of a planar gold wire, which is approximately 200 nm thick and 392 mm long, placed in a circle with a diameter of 2 mm. The model is well characterised by controlling the geometrical and electrical parameters and also the permeability of the magnetic material. To evaluate the feasibility of the model for virus monitoring, a novel inductive immunosensor is designed and for the first time applied for the detection of hepatitis B surface antigen (HBsAg). At first, Fab' segment of primary anti-HBsAg is immobilised on the coil. Then, the coil is exposed to HBsAg and the complex is introduced to a secondary antibody conjugated with magnetic particles to form an immune-sandwich. Finally, the influence of magnetic particles on the coil inductance is recorded and used as a signal for HBsAg detection. The magnetic inductive immunosensor showed specific responses toward HBsAg with the detection limit of 1 ng mL^-1, linear range of 1 to 200 ng mL^-1, and a sensitivity of 6 × 10^-4 mL ng^-1. The experimental results showed a very good agreement with simulation data indicating the compatibility of sensor sensitivity to the expected theoretical values. Graphical abstract.

Mathematical modeling of tumor-induced immunosuppression by myeloid-derived suppressor cells: Implications for therapeutic targeting strategies

Myeloid-derived suppressor cells (MDSCs) belong to immature myeloid cells that are generated and accumulated during the tumor development. MDSCs strongly suppress the anti-tumor immunity and provide conditions for tumor progression and metastasis. In this study, we present a mathematical model based on ordinary differential equations (ODE) to describe tumor-induced immunosuppression caused by MDSCs. The model consists of four equations and incorporates tumor cells, cytotoxic T cells (CTLs), natural killer (NK) cells and MDSCs. We also provide simulation models that evaluate or predict the effects of anti-MDSC drugs (e.g., l-arginine and 5-Fluorouracil (5-FU)) on the tumor growth and the restoration of anti-tumor immunity. The simulated results obtained using our model were in good agreement with the corresponding experimental findings on the expansion of splenic MDSCs, immunosuppressive effects of these cells at the tumor site and effectiveness of l-arginine and 5-FU on the re-establishment of antitumor immunity. Regarding this latter issue, our predictive simulation results demonstrated that intermittent therapy with low-dose 5-FU alone could eradicate the tumors irrespective of their origins and types. Furthermore, at the time of tumor eradication, the number of CTLs prevailed over that of cancer cells and the number of splenic MDSCs returned to the normal levels. Finally, our predictive simulation results also showed that the addition of l-arginine supplementation to the intermittent 5-FU therapy reduced the time of the tumor eradication and the number of iterations for 5-FU treatment. Thus, the present mathematical model provides important implications for designing new therapeutic strategies that aim to restore antitumor immunity by targeting MDSCs.

Friendship Network and Dental Brushing Behavior among Middle School Students: An Agent Based Modeling Approach

By using a standard questionnaire, the level of dental brushing frequency was assessed among 201 adolescent female middle school students in Tehran. The initial assessment was repeated after 5 months, in order to observe the dynamics in dental health behavior level. Logistic Regression model was used to evaluate the correlation among individuals' dental health behavior in their social network. A significant correlation on dental brushing habits was detected among groups of friends. This correlation was further spread over the network within the 5 months period. Moreover, it was identified that the average brushing level was improved within the 5 months period. Given that there was a significant correlation between social network's nodes' in-degree value, and brushing level, it was suggested that the observed improvement was partially due to more popularity of individuals with better tooth brushing habit. Agent Based Modeling (ABM) was used to demonstrate the dynamics of dental brushing frequency within a sample of friendship network. Two models with static and dynamic assumptions for the network structure were proposed. The model with dynamic network structure successfully described the dynamics of dental health behavior. Based on this model, on average, every 43 weeks a student changes her brushing habit due to learning from her friends. Finally, three training scenarios were tested by these models in order to evaluate their effectiveness. When training more popular students, considerable improvement in total students' brushing frequency was demonstrated by simulation results.