Design, Construction, and Implementation of a Magnetic Resonance Elastography Actuator for Research Purposes

Magnetic resonance elastography (MRE) is a technique for determining the mechanical response of soft materials using applied harmonic deformation of the material and a motion-sensitive magnetic resonance imaging sequence. This technique can elucidate significant information about the health and development of human tissue such as liver and brain, and has been used on phantom models (e.g., agar, silicone) to determine their suitability for use as a mechanical surrogate for human tissues in experimental models. The applied harmonic deformation used in MRE is generated by an actuator, transmitted in bursts of a specified duration, and synchronized with the magnetic resonance signal excitation. These actuators are most often a pneumatic design (common for human tissues or phantoms) or a piezoelectric design (common for small animal tissues or phantoms). Here, we describe how to design and assemble both a pneumatic and a piezoelectric MRE actuator for research purposes. For each of these actuator types, we discuss displacement requirements, end-effector options and challenges, electronics and electronic-driving requirements and considerations, and full MRE implementation. We also discuss how to choose the actuator type, size, and power based on the intended material and use. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Design, construction, and implementation of a convertible pneumatic MRE actuator for use with tissues and phantom models Basic Protocol 2: Design, construction, and implementation of a piezoelectric MRE actuator for localized excitation in phantom models.

Brain-mimicking phantom for biomechanical validation of motion sensitive MR imaging techniques

Motion sensitive MR imaging techniques allow for the non-invasive evaluation of biological tissues by using different excitation schemes, including physiological/intrinsic motions caused by cardiac pulsation or respiration, and vibrations caused by an external actuator. The mechanical biomarkers extracted through these imaging techniques have been shown to hold diagnostic value for various neurological disorders and conditions. Amplified MRI (aMRI), a cardiac gated imaging technique, can help track and quantify low frequency intrinsic motion of the brain. As for high frequency actuation, the mechanical response of brain tissue can be measured by applying external high frequency actuation in combination with a motion sensitive MR imaging sequence called Magnetic Resonance Elastography (MRE). Due to the frequency-dependent behavior of brain mechanics, there is a need to develop brain phantom models that can mimic the broadband mechanical response of the brain in order to validate motion-sensitive MR imaging techniques. Here, we have designed a novel phantom test setup that enables both the low and high frequency responses of a brain-mimicking phantom to be captured, allowing for both aMRI and MRE imaging techniques to be applied on the same phantom model. This setup combines two different vibration sources: a pneumatic actuator, for low frequency/intrinsic motion (1 Hz) for use in aMRI, and a piezoelectric actuator for high frequency actuation (30-60 Hz) for use in MRE. Our results show that in MRE experiments performed from 30 Hz through 60 Hz, propagating shear waves attenuate faster at higher driving frequencies, consistent with results in the literature. Furthermore, actuator coupling has a substantial effect on wave amplitude, with weaker coupling causing lower amplitude wave field images, specifically shown in the top-surface shear loading configuration. For intrinsic actuation, our results indicate that aMRI linearly amplifies motion up to at least an amplification factor of 9 for instances of both visible and sub-voxel motion, validated by varying power levels of pneumatic actuation (40%-80% power) under MR, and through video analysis outside the MRI scanner room. While this investigation used a homogeneous brain-mimicking phantom, our setup can be used to study the mechanics of non-homogeneous phantom configurations with bio-interfaces in the future.

Acute success and safety of the second-generation PVAC GOLD phased RF ablation catheter for atrial fibrillation

PURPOSE

The second-generation multi-electrode catheter, pulmonary vein ablation catheter (PVAC) GOLD, was designed to improve the delivery of phased radiofrequency energy and reduce procedure times using a 'single-shot' approach for pulmonary vein isolation (PVI), while retaining efficacy and safety. This large registry presents acute success rates and safety outcomes in a daily practice setting.

METHODS

A total of 1017 patients undergoing first-time ablation for atrial fibrillation (AF) using PVAC GOLD were included, 644 patients with paroxysmal AF and 373 patients with non-paroxysmal AF, divided into 175 patients receiving PVI only and 198 patients receiving PVI with additional substrate modification.

RESULTS

High and comparable percentages of successful PVI could be achieved in all groups (98%, 95% and 99%; p = 0.108). The median total procedure time for all groups was 90 min [70-100]. As expected, the total procedure, ablation and fluoroscopy time were significantly longer in the PVI + substrate modification group compared with the PVI-only cases (all p < 0.001), but not between the PVI-only groups (p = 0.306, p = 0.088, p = 0.233, respectively). A total of 44 complications were observed in 43 patients (4.2%). Major complications were seen in 19 patients (1.87%) and non-major procedure-related complications were seen in 25 patients (2.46%). Complications leaving permanent sequelae were rare and occurred in only four patients (0.39%). Complications did not differ between groups (p = 0.199, p = 0.438, p = 0.240 and p = 0.465 respectively).

CONCLUSION

PVAC GOLD performs successful PVI, while reducing procedure times and retaining safety for paroxysmal, persistent and long-standing persistent AF. Safety was unaffected by additional substrate modification.

Feasibility of multiplane microtransoesophageal echocardiographic guidance in structural heart disease transcatheter interventions in adults

Introduction

Structural heart interventions are guided by transoesophageal or intracardiac echocardiography (TEE/ICE). MicroTEE, developed for paediatric purposes, is smaller and therefore less invasive and traumatic, avoiding the need for general anaesthesia. We aimed to show feasibility of procedural guidance by comparing image quality of microTEE with standard TEE and ICE during adult transcatheter interventions, and assess the accuracy in obtaining left atrial appendage (LAA) measurements between the microTEE probe and standard TEE.

Methods and results

We prospectively included 49 patients (20 women, 64 ± 18 years). Intraprocedural images were obtained by using the microTEE probe and standard (2D and 3D) TEE (LAA closure, MitraClip implantation) or ICE (interatrial communication closure, transseptal puncture for left atrial ablation). Two echocardiographers independently assessed image quality from 1 (excellent) to 4 (poor) and performed LAA measurements. Use of microTEE was not related to significant discomfort. Image quality obtained with the microTEE probe was lower than with standard TEE (2 [1–2] vs. 1 [1–2]; p = 0.04) and comparable with ICE images (2 [1–2] vs. 2 [1–2], p = 0.13). MicroTEE showed a wider field of view than ICE. LAA measurements on images obtained by microTEE were strongly associated with standard TEE.

Conclusions

MicroTEE seems feasible for guidance during transcatheter heart interventions in adults. MicroTEE imaging offers a wider field of view than ICE, and its accuracy is comparable with TEE. In transcatheter interventions performed under conscious sedation, microTEE might be a viable and advantageous alternative to standard TEE or ICE.

Fluorescent Heterodoped Nanotetrapods as Synergistically Enhancing Positive and Negative Magnetic Resonance Imaging Contrast Agents

In this work, we report Mn-Fe heterodoped ZnSe tetrapod nanocrystals (NCs) synthesized to synergistically enhance contrast in both T1- and T2-weighted magnetic resonance imaging (MRI). The proposed NCs were prepared using a customized heteroarchitecture such that the manganese (Mn) is confined in the core and iron (Fe) in the branches of the tetrapods. The elemental composition and profile of these NCs were studied using X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy, and inductively coupled plasma mass spectroscopy. Photoluminescence quantum yield of these heterodoped NCs in water is ∼30%. Magnetic measurements reveal the simultaneous presence of superparamagnetic and paramagnetic behavior in these NCs because of the coexistence of Mn(2+) and Fe(2+) dopants. Their potential as simultaneous positive and negative MRI contrast agents was demonstrated by relaxivity measurements and in vivo MRI. From the in vivo studies, we also found that these NCs (with a hydrodynamic diameter of 20 nm) are excreted from the body within 24 h after the injection. Therefore, these heterodoped tetrapods NCs, while being fluorescent and safe, hold great future as a synergistically enhancing dual-modal MRI contrast agent.

Highly monodisperse low-magnetization magnetite nanocubes as simultaneous T(1)-T(2) MRI contrast agents

We report the first study of highly monodisperse and crystalline iron oxide nanocubes with sub-nm controlled size distribution (9.7 ± 0.5 nm in size) that achieve simultaneous contrast enhancement in both T1- and T2-weighted magnetic resonance imaging (MRI). Here, we confirmed the magnetite structure of iron oxide nanocubes by X-ray diffraction (XRD), selected area electron diffraction (SAED) pattern, optical absorption and Fourier transformed infrared (FT-IR) spectra. These magnetite nanocubes exhibit superparamagnetic and paramagnetic behavior simultaneously by virtue of their finely controlled shape and size. The magnetic measurements reveal that the magnetic moment values are favorably much lower because of the small size and cubic shape of the nanoparticles, which results in an enhanced spin canting effect. As a proof-of-concept demonstration, we showed their potential as dual contrast agents for both T1- and T2-weighted MRI via phantom studies, in vivo imaging and relaxivity measurements. Therefore, these low-magnetization magnetite nanocubes, while being non-toxic and bio-compatible, hold great promise as excellent dual-mode T1 and T2 contrast agents for MRI.

Production of a Novel Mineral-based Sun Lotion for Protecting the Skin from Biohazards of Electromagnetic Radiation in the UV Region

BACKGROUND

Sun protection materials have been one of the major concerns in pharmaceutical in-dustry since almost one century ago. Various materials have been found to have such an effect but there are still many unknown substances that have not been discovered. Objective : To introduce a novel mineral-based sun lotion with considerable UV absorption properties compared to commercially available sunscreens.

METHOD

 UV absorption properties of transparent plas-tic sheets covered by a uniform cream layer of different mineral-based sun lotions and a commercially available sun lotion were tested.

RESULTS

Sun lotions containing specific proportion of bentonite and zeolite minerals were capable of absorbing the highest level of UV light com-pared to that of the commercially available sun lotion.

CONCLUSION

Mineral-based sun lotions can be considered as cost effective alternatives for current commercial sunscreens.

High prevalence of HCV coinfection in HIV-infected individuals in Shiraz, Islamic Republic of Iran

We carried out a cross-sectional survey in Shiraz to determine the prevalence of hepatitis C virus (HCV) in 1 444 individuals infected with human immunodeficiency virus (HIV). We also determined the risk factors for this coinfection. Demographic and behavioural data were obtained using a standard questionnaire. The prevalence of HIV-HCV coinfection was 78.4% (95% CI: 76.3-80.5). Intravenous drug use (OR = 7.2; 95% CI: 4.9-10.6), imprisonment (OR = 6.9; 95% CI: 4.6-10.4), tattooing in prison (OR = 2.61; 95% CI: 1.4-4.8), tattooing out of prison (OR = 2.0; 95% CI: 1.3-3.1) and age (OR = 1.02 with increasing each year of life; 95% CI: 1.0-1.04) were significantly associated with HCV-HIV coinfection. Prevalence of HCV-HIV coinfection is high in Shiraz. Intravenous drug use and imprisonment are the main risk factors for this coinfection. Therefore, serious implementation of HIV and HCV testing, education, prevention, care and treatment programmes and evaluation of harm reduction programmes in prisons are very important.

Elastomer Nanocomposites Based on NR/EPDM/Organoclay: Morphology and Properties

Natural rubber/Ethylene Propylene Diene Monomer (NR/EPDM) blends of five different compositions (0/100), (25/75), (50/50), (75/25) and (100/0) with 1, 3, 5 and 7 phr organo-modified nanoclay (Cloisite 15A) were prepared by two-roll mill. The effect of organo-modified layered nanosilicates and composition on the cure characteristics, microstructure, mechanical, and rheological properties of the nanocomposites were studied. Results suggested the intercalation of polymer chains into the silicate layers which was evidenced by d-spacing results of X-ray diffraction patterns. TEM micrographs also directly confirmed XRD results. Mechanical properties of the nanocomposites depicted a nearly 40% percents increase respectively in the tensile modulus of 75NR/25EPDM containing 7 wt.% nanoclay.

The intermediary role of self-efficacy in relation with stress, glycosylated haemoglobin and health-related quality of life in patients with type2 diabetes

BACKGROUND

Stress is not always a direct result of stressful conditions, but rather the way they are perceived. Thus individual variables that may be associated with perceived stress should be examined in stress studies. This study investigates the intermediary role of self-efficacy in relation with stress, glycosylated haemoglobin and health-related quality of life in patients with type2 diabetes.

METHODS

All women with diabetes in Yazd Diabetes Research Centre, in 2012, were considered and 80 women were selected by random sampling. They completed Shirer's self-efficacy scale questionnaire, depression, anxiety and stress scale (DASS), and ADDQ0L19 questionnaire. Then they were introduced to the lab for blood test. Data were analysed by SPSS software and stepwise regression method.

RESULTS

Pearson correlation test results showed that the hemoglobin A1c (r = 0.35) and Quality of Life (r = -0.22) are associated with stress (P <0.05). As so hemoglobin A1c (r = 0.83) and Quality of Life (r = 0.37) with variable of self efficacy are associated positively and significantly (P <0.05). Results of stepwise regression also showed that self efficacy and stress scales 0.697 of variance hemoglobin A1c and 0.140 of variance of Quality of life explaining to do.

CONCLUSION

The impact of stress on blood sugar and patients' health-related quality of life can be influenced by their self-efficacy; therefore it is suggested that an educational intervention is done to increase patients' self-efficacy to better cope with stress in their life.

The impact of bystanding to workplace bullying on symptoms of depression among women and men in industry in Sweden: an empirical and theoretical longitudinal study

Background

Prospective studies on bystanding to workplace bullying and the health outcomes are scarce.

Aim

To investigate the work environmental risk factors of depressive symptoms among bystanders to bullying in both women and men in four large industrial organizations in Sweden.

Method

The number of respondents at four large industrial enterprises with more than one year at the workplace at T1: n = 2,563 (Women: n = 342; Men: n = 2,227). Bystanders to bullying at T1: n = 305 (Women: n = 30; Men: n = 275). The total number of those with symptoms of depression at T2: Women: n = 30; Men: n = 161. Two thousand one hundred and seventy-seven employees answered the questionnaire on T1 and T2 with an 18-month interval. “To have depressive symptoms” was defined as not having depressive symptoms at T1 but having depressive symptoms at T2.

Results

The number of men who were bystanders to bullying was larger compared to women. However, the proportion of women who were bystanders to bullying and developed depressive symptoms 18 months later was higher in comparison with men (33.3 and 16.4 %, respectively). Further, “Being a bystander to bullying” 1.69 (1.13–2.53), “Rumors of changes in the workplace” 1.53 (1.10–2.14), “Reduced role clarity” 2.30 (1.21–4.32), “Lack of appreciation of being in the group” 1.76 (1.22–2.53) increased the risk of future symptoms of depression. “Job Strain” was not an adjusted risk factor for depression.

Conclusion

Our results support previous findings that bystanding to workplace bullying is related to future depressive symptoms.

Mental health and well-being in different levels of perceived discrimination

BACKGROUND

To compare mental health and well-being in different levels of the perceived discrimination among Iranian people living in Tehran.

METHOD

Using multi-stage sampling, 1255 subjects with the average age of 45 years and 9 months (including 672 women and 583 men) were selected and they completed all items of the general health questionnaire (GHQ), the social well-being inventory (SWI), personal well-being inventory (PWI), and a question to assess the perceived discrimination.

RESULTS

Data analysis by Kruskal-Wallis test revealed that there were significant differences between physical symptoms (χ(2)=5.93, P<0.05) and depression (χ (2)=15.70, P<0.05), the subscales of mental health in different levels of the perceived discrimination. Furthermore, comparing personal well-being scores and its subscales in different levels of the perceived discrimination showed significant differences in personal hygiene (χ(2)=7.20, P<0.05), and security in future (χ(2)=7.60, P<0.05). Emotional well-being (χ(2)=12.25, P<0.05), self-rule (χ(2)=7.45, P<0.05), personal growth (χ(2)=19.87, P<0.05), and psychological well-being (χ(2)= 9.09, P<0.05) were significantly different in different levels of the perceived discrimination, too. Moreover, comparing social well-being in different levels of the perceived discrimination indicated significant differences between social acceptance (χ (2)=14.91, P<0.05), and social participation (χ (2)= 10.91, P<0.05).

CONCLUSION

Therefore, people are more active in society, increases the possibility of encountering with discrimination and consequently the perception of that.

Retrospective dosimetry using synthesized nano-structure hydroxyapatite

Micro and nano-structure hydroxyapatite samples were synthesized via several different methods. The samples were characterised utilising the Fourier transmission infra-red, scanning electron microscope and X-ray diffraction methods, to find out the structure most similar to human tooth enamel, and the best method was found. The electron paramagnetic resonance (EPR) signals of the gamma-irradiated samples were measured using an EPR spectrometer system. A calibration curve was established by irradiation of the samples at four doses of 50-500 mGy. The parameters of the calibration curve, slope and intercept with dose axis are determined by linear regression analysis. This calibration curve can be used for human tooth enamel for retrospective dosimetry purposes.

Toxoplasma infection in schizophrenia patients: a comparative study with control group

BACKGROUND

Schizophrenia is a serious, chronic, and often debilitating neuropsychiatric disorder. Its causes are still poorly understood. Besides genetic and non-genetic (environmental) factors are thought to be important as the cause of the structural and functional deficits that characterize schizophrenia. This study aimed to compare Toxoplasma gondii infection between schizophrenia patients and non-schizophrenia individuals as control group.

METHODS

A case-control study was designed in Tehran, Iran during 2009-2010. Sixty-two patients with schizophrenia and 62 non-schizophrenia volunteers were selected. To ascertain a possible relationship between T. gondii infection and schizophrenia, anti-Toxoplasma IgG antibodies were detected by indirect-ELISA. Data were statistically analyzed by chi- square at a confidence level of 99%.

RESULTS

The sero-positivity rate among patients with schizophrenia (67.7%) was significantly higher than control group (37.1) (P <0. 01).

CONCLUSION

A significant correlation between Toxoplasma infection and schizophrenia might be expected.

Cell-mediated lipoprotein transport: a novel anti-atherogenic concept

Lipoprotein transport is thought to occur in the plasma compartment of the blood, where lipoproteins are modulated by various enzymatic reactions. Subsequently, lipoproteins can migrate through the endothelial barrier to the subendothelial space or are taken up by the liver. The interaction between pro-atherogenic (apoB-containing) lipoproteins and blood cells (especially monocytes and macrophages) in the subendothelial space is well known. This lipoprotein-inflammatory cell interplay is central in the development of the atherosclerotic plaque. In this review, a novel interaction is described between lipoproteins and both leukocytes and erythrocytes in the blood compartment. This lipoprotein-blood cell interaction may also be related to the process of atherosclerosis by inducing inflammatory changes in the case of leukocytes (pro-atherogenic) and as an anti-atherogenic transport-system by adherence to erythrocytes. Triglyceride rich lipoprotein (TRL)-mediated leukocyte activation can lead to an inflammatory situation with generation of oxidative stress and the production of cytokines, ultimately resulting in acute endothelial dysfunction. Binding of apoB containing lipoproteins to erythrocytes may be a potential anti-atherogenic mechanism protecting the vessel wall from the pro-inflammatory effects of these lipoproteins and also playing a role in the removal of these particles from the circulation. One of the proposed mechanisms of this interaction implies complement activation on the lipoprotein surface and binding to the Complement Receptor 1 (CR1) on erythrocytes and leukocytes, followed by clearance by the liver.

Mannose binding lectin deficiency and triglyceride-rich lipoprotein metabolism in normolipidemic subjects

Mannose binding lectin (MBL) is one of the three initiators of complement activation and is therefore closely linked to inflammation. MBL deficiency has been associated with the generation of atherosclerosis. Since atherosclerosis, the complement system and postprandial lipemia are linked to inflammation, we studied postprandial lipoprotein metabolism in MBL deficiency. An observational study was carried out in 107 volunteers (21% MBL deficient). Classical cardiovascular risk factors were not different between subjects with and without MBL deficiency. Oral fat loading tests in 8 MBL deficient and 14 MBL sufficient subjects showed similar postprandial triglyceride, free fatty acid, hydroxybutyric acid and complement component 3 concentrations. MBL deficient subjects had 2.4 times lower postprandial Sf>400 (chylomicron)-apoB48 concentrations, but in contrast a 2-3.5 times increased Sf 60-400 (VLDL1-TG) and Sf 60-400-apoB100 response. MBL activity was inversely related to the postprandial Sf 60-400-TG increase. Despite lower postprandial Sf>400-apoB48 concentrations, MBL deficient subjects show an accumulation of Sf 60-400 lipoproteins.

Comparison of different methods to investigate postprandial lipaemia

Postprandial hyperlipidaemia has been associated with coronary artery disease (CAD). We investigated which of the generally used methods to test postprandial lipaemia differentiated best between patients with premature CAD (50+/-4 years, n=20) and healthy controls. Furthermore, the effects of rosuvastatin 40 mg/day on postprandial parameters were assessed. Standardised oral fat-loading tests (OFLT) and ambulant self-measurements of daylong capillary triglycerides (TGc) were performed. Total responses of individual lipoproteins, plasma TG (TGp) and remnant-like particle cholesterol (RLP-C) were estimated as area under the curve (AUC). Most AUCs were highest in untreated patients and reached control levels after rosuvastatin. From all AUCs, RLP-C-AUC was best associated to TGp-AUC in untreated patients and controls (adjusted R2=0.84, beta=0.92, p.

Postprandial inflammation and endothelial dysfuction

Postprandial hyperlipidaemia is a common metabolic disturbance in atherosclerosis. During the postprandial phase, chylomicrons and their remnants can penetrate the intact endothelium and cause foam cell formation. These particles are highly atherogenic after modification. People in the Western world are non-fasting for most of the day, which consequently leads to a continuous challenge of the endothelium by atherogenic lipoproteins and their remnants. Furthermore, atherosclerosis is considered a low-grade chronic inflammatory disease. Many studies have shown that the process of atherogenesis in part starts with the interaction between the activated leucocytes and activated endothelium. Postprandial lipoproteins can activate leucocytes in the blood and up-regulate the expression of leucocyte adhesion molecules on the endothelium, facilitating adhesion and migration of inflammatory cells into the subendothelial space. Another inflammatory process associated with postprandial lipaemia is the activation of the complement system. Its central component C3 has been associated with obesity, coronary sclerosis, the metabolic syndrome and fasting and postprandial TAGs (triacylglycerols). Moreover, chylomicrons are the strongest stimulators of adipocyte C3 production via activation of the alternative complement cascade. A postprandial C3 increment has been shown in healthy subjects and in patients with CAD (coronary artery disease) and with FCHL (familial combined hyperlipidaemia). Postprandial lipaemia has been related to TAG and free fatty acid metabolism. All of these mechanisms provide an alternative explanation for the atherogenicity of the postprandial period.