Dynamical Magnetic Response of Iron Oxide Nanoparticles Inside Live Cells

Magnetic nanoparticles exposed to alternating magnetic fields have shown a great potential acting as magnetic hyperthermia mediators for cancer treatment. However, a dramatic and unexplained reduction of the nanoparticle magnetic heating efficiency has been evidenced when nanoparticles are located inside cells or tissues. Recent studies suggest the enhancement of nanoparticle clustering and/or immobilization after interaction with cells as possible causes, although a quantitative description of the influence of biological matrices on the magnetic response of magnetic nanoparticles under AC magnetic fields is still lacking. Here, we studied the effect of cell internalization on the dynamical magnetic response of iron oxide nanoparticles (IONPs). AC magnetometry and magnetic susceptibility measurements of two magnetic core sizes (11 and 21 nm) underscored differences in the dynamical magnetic response following cell uptake with effects more pronounced for larger sizes. Two methodologies have been employed for experimentally determining the magnetic heat losses of magnetic nanoparticles inside live cells without risking their viability as well as the suitability of magnetic nanostructures for in vitro hyperthermia studies. Our experimental results-supported by theoretical calculations-reveal that the enhancement of intracellular IONP clustering mainly drives the cell internalization effects rather than intracellular IONP immobilization. Understanding the effects related to the nanoparticle transit into live cells on their magnetic response will allow the design of nanostructures containing magnetic nanoparticles whose dynamical magnetic response will remain invariable in any biological environments, allowing sustained and predictable in vivo heating efficiency

Identifying people at high risk for developing sleep apnea syndrome (SAS): a cross-sectional study in a Pakistani population

<p>Abstract</p> <p>Background</p> <p>Obstructive Sleep Apnea (OSA) is associated with many cardiovascular and psychiatric diseases. Day-time sleepiness is a common consequence of sleep apnea and correlates with road-traffic accidents (RTA). Pakistan has a high prevalence of factors which predispose an individual to OSA and death from RTAs are a huge burden. However there is a dearth of prevalence studies in this regard. We aim to understand local relevance of the disease and estimate the prevalence of individuals high-risk for OSA.</p> <p>Methods</p> <p>This cross-sectional survey was conducted among 450 individuals at Aga Khan University Hospital (AKUH), which is a tertiary care teaching hospital in Pakistan. We used the BQ as our measurement tool. Based on the responses, participants were grouped into high or low-risk for OSA.</p> <p>Results</p> <p>Our study sample size was 418 with 63.2% males. Mean age of our study population was 30.4 SD +/- 12.3 years; and mean BMI was 23.2 SD +/- 5 kg/m2. Out of the total sample size 24.9% reported snoring and there were twice as many males who snored as compared to females. Forty-five individuals reported that they had nodded off to sleep while driving at least once in their lifetime. On the other hand, the highest proportion of high risk individuals 47.6% was found in the age group 60 or above. The overall prevalence of individuals who were high risk for sleep apnea was 10%.</p> <p>Conclusion</p> <p>A significant proportion of the population is at high-risk for OSA. Our study shows that despite low BMI and favorable craniofacial anatomy sleep apnea is still a locally relevant disease. Given the local relevance of OSAS, it is important to increase awareness among general population but more importantly among physicians of the developing countries, like Pakistan, about common clinical features and pertinent risk factors and complications of OSAS.</p

Whither Magnetic Hyperthermia? A Tentative Roadmap

The scientific community has made great efforts in advancing magnetic hyperthermia for the last two decades after going through a sizeable research lapse from its establishment. All the progress made in various topics ranging from nanoparticle synthesis to biocompatibilization and in vivo testing have been seeking to push the forefront towards some new clinical trials. As many, they did not go at the expected pace. Today, fruitful international cooperation and the wisdom gain after a careful analysis of the lessons learned from seminal clinical trials allow us to have a future with better guarantees for a more definitive takeoff of this genuine nanotherapy against cancer. Deliberately giving prominence to a number of critical aspects, this opinion review offers a blend of state-of-the-art hints and glimpses into the future of the therapy, considering the expected evolution of science and technology behind magnetic hyperthermia

Spin polarization of carriers in InGaAs self-assembled quantum rings inserted in GaAs-AlGaAs resonant tunneling devices

In this work, we have investigated transport and polarization resolved photoluminescence (PL) of n-type GaAs-AlGaAs resonant tunneling diodes (RTDs) containing a layer of InGaAs self-assembled quantum rings (QRs) in the quantum well (QW). All measurements were performed under applied voltage, magnetic fields up to 15 T and using linearly polarized laser excitation. It was observed that the QRs’ PL intensity and the circular polarization degree (CPD) oscillate periodically with applied voltage under high magnetic fields at 2 K. Our results demonstrate an effective voltage control of the optical and spin properties of InGaAs QRs inserted into RTDs

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Nanoparticle-based hyperthermia distinctly impacts production of ROS, expression of Ki-67, TOP2A, and TPX2, and induction of apoptosis in pancreatic cancer

Robert Ludwig,1 Francisco J Teran,2,3 Ulf Teichgraeber,1 Ingrid Hilger1 1Department of Experimental Radiology, Institute for Diagnostic and Interventional Radiology, Jena University Hospital &ndash; Friedrich Schiller University Jena, Jena, Germany; 2iMdea-Nanociencia, Campus Universitario de Cantoblanco, 3Nanobiotecnolog&iacute;a (iMdea-Nanociencia), Unidad Asociada al Centro Nacional de Biotecnolog&iacute;a (CSIC), Madrid, Spain Abstract: So far, the therapeutic outcome of hyperthermia has shown heterogeneous responses depending on how thermal stress is applied. We studied whether extrinsic heating (EH, hot air) and intrinsic heating (magnetic heating [MH] mediated by nanoparticles) induce distinct effects on pancreatic cancer cells (PANC-1 and BxPC-3 cells). The impact of MH (100 &micro;g magnetic nanoparticles [MNP]/mL; H=23.9 kA/m; f=410 kHz) was always superior to that of EH. The thermal effects were confirmed by the following observations: 1) decreased number of vital cells, 2) altered expression of pro-caspases, and 3) production of reactive oxygen species, and 4) altered mRNA expression of Ki-67, TOP2A, and TPX2. The MH treatment of tumor xenografts significantly (P&le;0.05) reduced tumor volumes. This means that different therapeutic outcomes of hyperthermia are related to the different responses cells exert to thermal stress. In particular, intratumoral MH is a valuable tool for the treatment of pancreatic cancers. Keywords: iron oxide nanoparticles, magnetic hyperthermia, heat dose, nanomedicine, proliferation marke

Unraveling viscosity effects on the hysteresis losses of magnetic nanocubes.

Hysteresis losses in magnetic nanoparticles constitute the basis of magnetic hyperthermia for delivering a local thermal stress. Nevertheless, this therapeutic modality is only to be realised through a careful appraisal of the best possible intrinsic and extrinsic conditions to the nanoparticles for which they maximise and preserve their heating capabilities. Low frequency (100 kHz) hysteresis loops accurately probe the dynamical magnetic response of magnetic nanoparticles in a more reliable manner than calorimetry measurements, providing conclusive quantitative data under different experimental conditions. We consider here a set of iron oxide or cobalt ferrite nanocubes of different sizes, through which we experimentally and theoretically study the influence of the viscosity of the medium on the low frequency hysteresis loops of magnetic colloids, and hence their ability to produce and dissipate heat to the surroundings. We analyse the role of nanoparticle size, size distribution, chemical composition, and field intensity in making the magnetisation dynamics sensitive to viscosity. Numerical simulations using the stochastic Landau-Lifshitz-Gilbert equation model the experimental observations in excellent agreement. These results represent an important contribution towards predicting viscosity effects and hence to maximise heat dissipation from magnetic nanoparticles regardless of the environment