Stripe domains reorientation in ferromagnetic films with perpendicular magnetic anisotropy

International audienceFerromagnetic thin films with moderate perpendicular magnetic anisotropy (PMA) are known to support weak stripe domains provided film thickness exceeds a critical value. In this work, we performed both an experimental and theoretical investigation of a peculiar phenomenon shown by weak stripe domains: namely, the stripe domains reorientation when a dc magnetic field is applied in the film plane along the direction perpendicular to the stripes axis. We focus on bct α ′-Fe 8 N 1−x thin films obtained by N 2 irradiation of α-Fe films epitaxially grown on ZnSe/ GaAs(001). By using different ion implantation and heat treatment conditions, we show that it is possible to tune the PMA values. Magnetic force microscopy and vibrating sample magnetometer measurements prove the existence of weak stripe domains at remanence, and of a threshold field for the reorientation of the stripes axis in a transversal field. Using a one-dimensional model of the magnetic stripe domains, where the essential parameter is the maximum canting angle of the stripe magnetization out of the film plane, the various contributions to the magnetic energy can be separately calculated. A linear increase of the reorientation threshold field Stripe domains reorientation in ferromagnetic films with PMA 2 on the PMA is obtained, in qualitative agreement with experimental data in our Fe-N films, as well as in other thin films with weak stripe domains. Finally, we find that also the rotatable anisotropy field linearly increases as a function of the PMA magnitude

Glucose Alterations, Insulin Resistance, Arterial Hypertension, and Renin are Strictly Associated in Pediatric Obesity

Context Insulin resistance, glucose alterations, arterial hypertension (HTN), and the renin-angiotensin-aldosterone system (RAAS) are related in adult obesity. This crosstalk is still unexplored in childhood. Objective Characterize the relationships of fasting and postload glucose and insulin levels with new American Academy of Pediatrics classification of HTN and RAAS in pediatric obesity. Methods This was a retrospective observational study; 799 pediatric outpatients (11.4 & PLUSMN; 3.1 years) at a tertiary center who were overweight or obese and not yet on diet were included. The main outcome measures were mean and correlations among parameters of a complete clinical and metabolic screening (body mass index, blood pressure, and glucose and insulin levels during an oral glucose tolerance test, and renin and aldosterone levels and their ratio). Results 774 subjects had all the parameters, of whom 87.6% had HTN (5% elevated blood pressure, 29.2% stage I HTN, and 53.4% stage II HTN). Eighty subjects had 1 or more glucose alterations, and more frequently presented HTN. Blood pressure levels were higher in subjects with glucose alterations than in those with normal glucose levels. Fasting and stimulated glucose and insulin levels were directly related to the HTN stages, and insulin sensitivity was lower in HTN than in normal blood pressure. Aldosterone, renin, and aldosterone-renin ratio (ARR) were similar in sexes, whereas aldosterone was higher in prepubertal individuals. Subjects with impaired glucose tolerance (IGT) had higher renin and lower ARR. Renin was positively correlated with postload glucose, and ARR was negatively correlated with the Homeostatic Model Assessment for Insulin Resistance index. Conclusion A close relationship exists among insulin resistance, glucose alterations, HTN, and renin in childhood obesity. Specific categories of risk could provide indicators for strict clinical surveillance

Next-Generation Sequencing and <i>In Vitro</i> Expression Study of <i>ADAMTS13</i> Single Nucleotide Variants in Deep Vein Thrombosis

<div><p>Background</p><p>Deep vein thrombosis (DVT) genetic predisposition is partially known.</p><p>Objectives</p><p>This study aimed at assessing the functional impact of nine <i>ADAMTS13</i> single nucleotide variants (SNVs) previously reported to be associated as a group with DVT in a burden test and the individual association of selected variants with DVT risk in two replication studies.</p><p>Methods</p><p>Wild-type and mutant recombinant ADAMTS13 were transiently expressed in HEK293 cells. Antigen and activity of recombinant ADAMTS13 were measured by ELISA and FRETS-VWF73 assays, respectively. The replication studies were performed in an Italian case-control study (Milan study; 298/298 patients/controls) using a next-generation sequencing approach and in a Dutch case-control study (MEGA study; 4306/4887 patients/controls) by TaqMan assays.</p><p>Results</p><p><i>In vitro</i> results showed reduced ADAMTS13 activity for three SNVs (p.Val154Ile [15%; 95% confidence interval [CI] 14–16], p.Asp187His [19%; 95%[CI] 17–21], p.Arg421Cys [24%; 95%[CI] 22–26]) similar to reduced plasma ADAMTS13 levels of patients carriers for these SNVs. Therefore these three SNVs were interrogated for risk association. The first replication study identified 3 heterozygous carriers (2 cases, 1 control) of p.Arg421Cys (odds ratio [OR] 2, 95%[CI] 0.18–22.25). The second replication study identified 2 heterozygous carriers (1 case, 1 control) of p.Asp187His ([OR] 1.14, 95%[CI] 0.07–18.15) and 10 heterozygous carriers (4 cases, 6 controls) of p.Arg421Cys ([OR] 0.76, 95%[CI] 0.21–2.68).</p><p>Conclusions</p><p>Three SNVs (p.Val154Ile, p.Asp187His and p.Arg421Cys) showed reduced <i>ex vivo</i> and <i>in vitro</i> ADAMTS13 levels. However, the low frequency of these variants makes it difficult to confirm their association with DVT.</p></div

Western blot of WT and mutant p.Y603C recombinant ADAMTS13 expressed in HEK293 cells.

<p>WT and mutant recombinant protein were detected in the conditioned media (left) and cell lysates (right). Cellular alpha-tubulin was used as control to verify equal total protein loading and detected using anti-alpha-tubulin monoclonal antibody (bottom). (M) Marker; C-, medium and lysate of untransfected cells used as a negative control. The amount of each mutant rADAMTS13 contained in cell lysates was normalized using the respective band of alpha-tubulin (loading control), quantified by densitometry analysis and referred to the WT taken as 100%.</p

Western blot of WT and mutant p.V154I, p.D187H and p.R421C recombinant ADAMTS13 expressed in HEK293 cells.

<p>WT and mutant recombinant proteins were detected in the conditioned media (A) and cell lysates (B). Cellular alpha-tubulin was used as control to verify equal total protein loading and detected using anti-alpha-tubulin monoclonal antibody (bottom). (M) Marker. The amount of each mutant rADAMTS13 contained in cell lysates was normalized using the respective band of alpha-tubulin (loading control), quantified by densitometry analysis and referred to the WT taken as 100%.</p

Characteristics of genotyped single nucleotide variants (SNVs) in Italian and Dutch populations.

<p>Characteristics of genotyped single nucleotide variants (SNVs) in Italian and Dutch populations.</p

Rare previously identified <i>ADAMTS13</i> SNVs associated with DVT.

<p>Rare previously identified <i>ADAMTS13</i> SNVs associated with DVT.</p

<i>In vitro</i> expression studies results.

<p><i>In vitro</i> expression studies results.</p