Cofactor-specific covalent anchoring of cytochrome b 562 on a single-walled carbon nanotube by click chemistry †

International audienceRedox-active cytochrome b 562 with a tethered azide group on the heme propionate side chain is covalently linked to an acetylene moiety introduced on the sidewall of a single-walled carbon nanotube (SWNT) by copper-catalyzed click chemistry forming a triazole ring with the heme active site directly linked to the SWNT. The cytochrome b 562 –SWNT hybrid is characterized by electrochemistry and atomic force microscopy. Interfacing redox-active enzymes with electrode materials is a key technology used in the development of high performance biosensors and biofuel cells. 1–3 Recent advances in carbon nanomaterials have enabled us to design hybrid systems with linked enzymes. Carbon nanotubes (CNTs), of the single-or multi-walled type, are promising building blocks for fabrication of hybrid materials. 4–8 CNTs have large surface areas, high strength, chemical stability, and attractive electronic properties. CNTs have also provided a wide variety of synthetic tools applicable for introduction of a range of substituents for linking the enzymes. A copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction is a widely utilized method used to form a covalent linkage which includes a triazole ring between building blocks containing azide and alkyne groups. 9,10 The CuAAC reaction has thus been used in organic synthesis, bio-conjugation chemistry, and surface chemistry. This powerful coupling reaction can be applied in efforts to efficiently tailor the chemical modication of single-walled CNTs (SWNTs) to construct hybrid materials 11–13 including enzymes. 14 Redox-active hemoproteins form a major class of enzymes that are useful for constructing enzyme-immobilized electrodes due to their diverse functions including electron transfer, catal-ysis, and sensing. 15–25 Many hemoproteins possess a replaceable heme b cofactor in the heme pocket, enabling immobilization on the electrode via the heme–heme pocket interaction. 26–45 In this paper, we demonstrate specically oriented covalent immobili-zation of azide-linked cytochrome b 562 (CYT) on the sidewall of SWNT using the CuAAC reaction (Fig. 1). The advantage of this method which uses a replaceable heme tethered to an azide moiety, lies in the wide range of applications for functionaliza-tion of wild-type hemoproteins. The characterization and elec-trochemical properties of the covalently-linked hybrid materials of SWNT and cytochrome b 562 are described. Fig. 1 (a) SWNT with covalently-linked cytochrome b 562 and (b) the preparation scheme using a copper-catalyzed azide–alkyne cyclo-addition (CuAAC) reaction

Distortion of the outer boundary of the closed region in the Tsyganenko magnetic field model

Using the Tsyganenko magnetic field model (TSYGANENKO, Planet. Space Sci., 37, 5, 1989) we make an attempt to determine the outer boundary of the closed region when the interplanetary magnetic field (IMF) is southward. As a simple magnetic field model including the effect of IMF B_z<0, the B_z component of a constant value of minus a few nanoTeslas is added to the magnetic field in the Tsyganenko model with low K_p values. In this paper, if the magnetic field strength, B, is not less than 2 nT in the whole range of a field line (namely the minimum B along a field line is greater than 2 nT), this field line is judged to be "firmly" closed. The firmly closed field lines are thought to be definitely closed as long as the fluctuation amplitude of B_z (around its average level) in the interplanetary (solar wind) magnetic field is less than 2 nT. The outer boundary of the firmly closed region is then constituted by field lines with the minimum B of 2 nT. This boundary is found to be close to (just inside of) the open-closed boundary, which can be determined with accuracy of 0.01° in latitude of the foot point of a field line. It is found that a circle with the center at a latitude of about 85° on the midnight meridian can be fitted to the outer boundary of the firmly closed region, as it is projected to the ionosphere. Interestingly this circle coincides with a typical auroral circle; the auroral circles are those delineating the poleward boundary of the quiet auroral belt, which were earlier identified from the statistical analysis of satellites\u27 auroral images by MENG et al. (J. Geophys. Res., 82, 164, 1977). Importantly we find that the outer boundary of the firmly closed region is "distorted" on the nightside in the sense that the ionospheric projection of the average magnetic drift velocity of a plasma with isotropic pressure is not parallel to the boundary; more specifically, that of an isotropic ion fluid has an equatorward component on the duskside boundary and a poleward one on the dawnside boundary, respectively. This kind of the boundary distortion may be one of the possible causes of the generation of the nightside region 1 field-aligned current, which has been first suggested by HRUSKA (J. Geophys. Res., 91, 371, 1986) and recently, further studied by YAMAMOTO and INOUE (Proc. NIPR Symp. Upper Atmos. Phys., 11, 106, 1998)

Understanding the pincer - The importance of reference plane orientation on acetabular rim evaluation

Objectives: Femoroacetabular impingement (FAI) is a common cause of young adult hip pain. FAI can result from an acetabular-sided bony lesion, or “pincer” lesion. A pincer lesion is defined as an area of linear contact between the acetabular rim and the femoral head-neck junction due to general or focal acetabular overcoverage. Three dimensional (3D) analysis of the acetabular rim morphology is essential to understand etiology and aciculate diagnosis of the of the pincer type FAI. A few studies have measured 3D geometry of the acetabular rim; in which the acetabular rim is described as a deviation from a reference plane. Therefore, the definition of the reference plane is critical to determine the acetabular rim geometry. The purpose of this study was to use 3D Computed Tomography (CT) modeling to evaluate the impact of varied acetabular orientation reference planes on the interpretation of acetabular rim abnormalities, with the goal to determine the ideal reference plane for future study use. Methods: 3D CT modeling was performed on five hip joints of patients who underwent hip arthroscopy with acetabular trimming for a presumed pincer lesion. These models were exported into point-cloud models. An acetabular 3D model was automatically created within 10 mm from the femoral head surface (Fig. 1A,B). The acetabular articular surface and rim were separated with a threshold of 5 mm, which provided an acetabular rim model with a band width of 5 mm (Fig. 1C). A local coordinate system was defined with the acetabular notch midpoint being 6 o’clock. A best-fit plane of the acetabular rim was determined by the least square method using two different acetabular rim models: 1) a model excluding the acetabular notch (plane A) and 2) a model excluding the acetabular notch and superior region from 10:30 to 3:00 (3:00 being anterior) (plane B). The acetabular rim model was transformed into a cylindrical coordinate system with an axis determined by a normal vector of the plane. The final acetabular rim model consisting of 120 points with 3° increments was created by searching the outermost points of the rim. The acetabular center was determined using best-fit sphere of the articular surface model. A reference plane including the center point was determined with orientations determined by normal vectors of the acetabular rim planes (Fig. 1C, yellow line). The 3D geometry of the rim was described by subtended angles from the normal vector of the reference plane. Results: Three distinct peaks were noted at anteroinferior (AI), anterosuperior (AP) and posteroinferior (PI) regions (Fig. 2 A,B). While the AI and PI peaks measured with the plane A were higher than that measured with plane B, the AP peak measured with plane A was lower than that measured with plane B (Fig. 2C). The angle between the normal vectors of plane A and B was 13.7±3.5°. Conclusion: The findings demonstrate that the orientation of the reference plane is critical to the 3D measurement of the acetabular rim. Since bony prominence in the anterosuperior region has been considered as the pathogenesis of the impingement, the reference plane including this region may cause underestimation of the bony lesion. An appropriate determination of the reference plane is crucial for evaluation of the bony lesion in the pincer FAI patient. © The Author(s) 2013

Latent trajectory modelling of pulmonary artery pressure in systemic sclerosis: a retrospective cohort study

OBJECTIVES: To visualise the trajectories of pulmonary arterial pressure (PAP) in systemic sclerosis (SSc) and identify the clinical phenotypes for each trajectory, by applying latent trajectory modelling for PAP repeatedly estimated by echocardiography. METHODS: This was a multicentre, retrospective cohort study conducted at four referral hospitals in Kyoto, Japan. Patients with SSc who were treated at study sites between 2008 and 2021 and who had at least three echocardiographic measurements of systolic PAP (sPAP) were included. A group-based trajectory model was applied to the change in sPAP over time, and patients were classified into distinct subgroups that followed similar trajectories. Pulmonary hypertension (PH)-free survival was compared for each trajectory. Multinomial logistic regression analysis was performed for baseline clinical characteristics associated with trajectory assignment. RESULTS: A total of 236 patients with 1097 sPAP measurements were included. We identified five trajectories: rapid progression (n=9, 3.8%), early elevation (n=30, 12.7%), middle elevation (n=54, 22.9%), late elevation (n=24, 10.2%) and low stable (n=119, 50.4%). The trajectories, in the listed order, showed progressively earlier elevation of sPAP and shorter PH-free survival. In the multinomial logistic regression analysis with the low stable as a reference, cardiac involvement was associated with rapid progression, diffuse cutaneous SSc was associated with early elevation and anti-centromere antibody was associated with middle elevation; older age of onset was associated with all three of these trajectories. CONCLUSION: The pattern of changes in PAP over time in SSc can be classified into five trajectories with distinctly different clinical characteristics and outcomes

A novel clinical entity, IgG4-related disease (IgG4RD): general concept and details

IgG4-related disease (IgG4RD) is a novel clinical disease entity characterized by elevated serum IgG4 concentration and tumefaction or tissue infiltration by IgG4-positive plasma cells. IgG4RD may be present in a certain proportion of patients with a wide variety of diseases, including Mikulicz’s disease, autoimmune pancreatitis, hypophysitis, Riedel thyroiditis, interstitial pneumonitis, interstitial nephritis, prostatitis, lymphadenopathy, retroperitoneal fibrosis, inflammatory aortic aneurysm, and inflammatory pseudotumor. Although IgG4RD forms a distinct, clinically independent disease category and is attracting strong attention as a new clinical entity, many questions and problems still remain to be elucidated, including its pathogenesis, the establishment of diagnostic criteria, and the role of IgG4. Here we describe the concept of IgG4RD and up-to-date information on this emerging disease entity