Time of Dietary Energy and Nutrient Intake and Body Mass Index in Children: Compositional Data Analysis from the Childhood Obesity Project (CHOP) Trial

Meal timing is suggested to influence the obesity risk in children. Our aim was to analyse the effect of energy and nutrient distributions at eating occasions (EO), including breakfast, lunch, supper, and snacks, on the BMI z-score (zBMI) during childhood in 729 healthy children. BMI and three-day dietary protocols were obtained at 3, 4, 5, 6, and 8 years of age, and dietary data were analysed as the percentage of the mean total energy intake (TEI; %E). Intakes at EOs were transformed via an isometric log–ratio transformation and added as exposure variables to linear mixed-effects models. Stratified analyses by country and recategorization of EOs by adding intake from snacks to respective meals for further analyses were performed. The exclusion of subjects with less than three observations and the exclusion of subjects who skipped one EO or consumed 5% energy or less at one EO were examined in sensitivity analyses. Around 23% of the children were overweight at a given time point. Overweight and normal-weight children showed different distributions of dietary intakes over the day; overweight children consumed higher intakes at lunch and lower intakes of snacks. However, no significant effects of timing of EOs on zBMI were found in regression analyses.     

Nosocomial outbreak by NDM-1-producing Klebsiella pneumoniae highly resistant to cefiderocol,Florence, Italy,August 2021 to June 2022

A nosocomial outbreak by cefiderocol (FDC)-resistant NDM-1-producing Klebsiella pneumoniae (NDM-Kp) occurred in a large tertiary care hospital from August 2021–June 2022 in Florence, Italy, an area where NDM-Kp strains have become endemic. Retrospective analysis of NDM-Kp from cases observed in January 2021–June 2022 revealed that 21/52 were FDC-resistant. The outbreak was mostly sustained by clonal expansion of a mutant with inactivated cirA siderophore receptor gene, which exhibited high-level resistance to FDC (MIC ≥ 32 mg/L) and spread independently of FDC exposure.     

Instant in situ formation of a polymer film at the water–oil interface

The water–oil interface is an environment that is often found in many contexts of the natural sciences and technological arenas. This interface has always been considered a special environment as it is rich in different phenomena, thus stimulating numerous studies aimed at understanding the abundance of physico-chemical problems that occur there. The intense research activity and the intriguing results that emerged from these investigations have inspired scientists to consider the water–oil interface even as a suitable setting for bottom-up nanofabrication processes, such as molecular self-assembly, or fabrication of nanofilms or nano-devices. On the other hand, biphasic liquid separation is a key enabling technology in many applications, including water treatment for environmental problems. Here we show for the first time an instant nanofabrication strategy of a thin film of biopolymer at the water–oil interface. The polymer film is fabricated in situ, simply by injecting a drop of polymer solution at the interface. Furthermore, we demonstrate that with an appropriate multiple drop delivery it is also possible to quickly produce a large area film (up to 150 cm²). The film inherently separates the two liquids, thus forming a separation layer between them and remains stable at the interface for a long time. Furthermore, we demonstrate the fabrication with different oils, thus suggesting potential exploitation in different fields (e.g. food, pollution, biotechnology). We believe that the new strategy fabrication could inspire different uses and promote applications among the many scenarios already explored or to be studied in the future at this special interface environment.

A completely new method for easy and quick formation of a thin polymer film at the special setting of a stratified oil/water interface. Morphological SEM and quantitative full-field characterization have been reported using digital holography.     

Balloon-assisted,ultrasound-guided percutaneous real-time thrombin injection,for the arteriovenous fistula pseudoaneurysm treatment

A pseudoaneurysm or false aneurysm is the consequence of a persistent blood leak caused generally by iatrogenic rupture of a vessel wall. The blood leak creates a new cavity delimited by surrounding tissues and allows blood flow to remain in continuity between this cavity and the vessel. In hemodialysis fistula, pseudoaneurysm generally results from repeated puncturing of the vein at the same site, leading to a bulging anatomical defect in the vein. Over the past few years, interventional radiological treatment has evolved and taken the place of surgery, with different kinds of percutaneous and endovascular treatment methods in pseudoaneurysm management. We reported a case report of successful treatment of arteriovenous fistula pseudoaneurysm with no-measurable neck. We performed ultrasound-guided percutaneous direct thrombin injection while an inflated balloon transiently obstructed flow out of the pseudoaneurysm, in order prevent non-target embolization.     

Titin activates myosin filaments in skeletal muscle by switching from an extensible spring to a mechanical rectifier

Titin is a molecular spring in parallel with myosin motors in each muscle half-sarcomere, responsible for passive force development at sarcomere length (SL) above the physiological range (>2.7 μm). The role of titin at physiological SL is unclear and is investigated here in single intact muscle cells of the frog (Rana esculenta), by combining half-sarcomere mechanics and synchrotron X-ray diffraction in the presence of 20 μM para-nitro-blebbistatin, which abolishes the activity of myosin motors and maintains them in the resting state even during activation of the cell by electrical stimulation. We show that, during cell activation at physiological SL, titin in the I-band switches from an SL-dependent extensible spring (OFF-state) to an SL-independent rectifier (ON-state) that allows free shortening while resisting stretch with an effective stiffness of ~3 pN nm⁻¹ per half-thick filament. In this way, I-band titin efficiently transmits any load increase to the myosin filament in the A-band. Small-angle X-ray diffraction signals reveal that, with I-band titin ON, the periodic interactions of A-band titin with myosin motors alter their resting disposition in a load-dependent manner, biasing the azimuthal orientation of the motors toward actin. This work sets the stage for future investigations on scaffold and mechanosensing-based signaling functions of titin in health and disease.

Contraction of the striated muscle is powered by the cyclical adenosine triphosphate (ATP)-fueled interactions of the motor protein myosin II, arranged in two bipolar arrays on thick filaments originating at the midpoint of each sarcomere (M-line), with the nearby thin, actin-containing filaments originating at the sarcomere extremities (Z-line, Fig. 1A). In the half-sarcomere, myosin motors are mechanically coupled as parallel force generators and the collective force depends on the number of motors available for actin attachment and thus on the degree of overlap between thick and thin filaments (Fig. 1B, black circles; ref. 1). The half-sarcomere is the basic functional unit in which the emergent properties from the arrays of myosin motors, the interdigitating thin filaments, and a “third” filament made by the cytoskeleton protein titin (Fig. 1C) account for the mechanical performance of muscle and its regulation.Open in a separate windowFig. 1.Structure–function of myofilaments and titin in relation to the length of the sarcomere. (A) Overview of the thick filament (blue), myosin motors (orange), and thin filament (yellow) at SL 2.2 μm (full overlap) and 3.0 μm (partial overlap). (B) Relation between SL and either active force at the plateau of the isometric tetanic contraction (black circles, linear fit to points at SL >2.2 μm, continuous line) or passive force (triangles, fitted with an exponential equation (red dashed line) and with the model (red circles) described in SI Appendix, Supporting Note 1 and Fig. S1). Data from ref. 2. (C) Protein disposition on the thin (yellow) and thick (light blue) filaments in the half-sarcomere at rest at 2.2 μm SL. M-line on the right and Z-line on the left. Inset: Overlap region on an enlarged scale to show with better resolution the ~38 nm axial periodicity of the troponin complex (gray) along the thin filament and the two motor domains (orange) of each myosin molecule tilted back on their tail (blue) in the OFF state (3, 4). The 49 crowns of motors are numbered starting from the M-line; thin filament with tropomyosin (brown) and troponin complex (gray); MyBP-C (green) aligned with myosin triplets from crowns 12 to 30. Titin (magenta) with PEVK segment identified by dark magenta. HBZ, half-bare zone. P-, C-, and D-zones, proximal, MyBP-C containing and distal zones. Only two of the six titin molecules and only one of the three series of MyBP-C molecules per htf are represented for clarity. (D) Straightening of the proximal tandem Ig segment by passive stretch to 3.0 μm SL.Titin is a giant protein (up to 4 MDa) that spans the half-sarcomere (Fig. 1C, magenta), first through the I-band, connecting the Z-line with the tip of the thick filament, and then through the A-band, associated with the thick filament (six molecules per thick filament; refs. 5, 6) up to the M-line at the center of the sarcomere (7–9). The titin I-band region acts as a spring able to transmit the stress also when no myosin motors are attached to actin. In the muscle fiber of the frog, in which there is no contribution from extracellular matrix components (10, 11), titin is responsible for the passive force when the muscle cell is stretched at rest (Fig. 1B, triangles; refs. 12–16). Within the I-band titin, the distal tandem immunoglobulin-like segment forms a stiff end-filament composed of the six titin molecules attaching to the tip of the thick filament (17, 18), while the other two segments account for titin extensibility: the proximal tandem Ig segment (hereinafter called tandem Ig segment) and the unique sequence rich in proline (P), glutamate (E), valine (V), and lysine (K) residues (PEVK segment). Both spring-like segments exhibit variable muscle-type specific lengths (7, 19), which account for the differences in passive force–sarcomere length (SL) relations (20). In situ studies using immunofluorescence and immunoelectron microscopy on skinned fibers and myofibrils from mammalian skeletal muscle demonstrated that the large extensibility of the muscle sarcomere at SL < 2.7 μm is enabled by straightening out of randomly bent elements of the tandem Ig segment. At longer SL, at which the tandem Ig segment approaches its contour length, the passive force increases more steeply, reflecting the PEVK segment stiffness (SI Appendix, Supporting Note 1 and Fig. S1; see refs. 21–25).Titin in the A-band is composed of Ig and fibronectin (Fn) domains each ~4 nm long, with two distinct domain superrepeats: 11 “C-type” superrepeats, each composed of 11 Ig-Fn domains, extending from about layer 3 to 37 of the myosin crowns, and 6 “D-type” superrepeats, each composed of seven Ig-Fn domains, extending from about layer 38 to the filament tip (Fig. 1C; refs. 7, 26–28). The A-band region of titin is made inextensible by its association to the other proteins in the thick filament, myosin, and the Myosin Binding Protein C (MyBP-C), an accessory protein that is bound with its C terminus to the central one-third of the half-thick filament (htf) (C-zone, from layer 12 to 30, Fig. 1C) and extends from the thick filament backbone to establish dynamic interactions with the thin filament (2, 29–31) with its N terminus.I-band titin transmits any pulling force exerted on the extremity of the half-sarcomere to the tip of the thick filament and in this way could play a role in thick filament mechanosensing that switches myosin motors ON (3, 32). Moreover, as an elastic element in parallel with motors, I-band titin could preserve the homogeneity of sarcomeres during contraction, by preventing the lengthening of weak half-sarcomeres. However, titin-dependent passive force typically rises steeply only at SL > 2.6 µm (Fig. 1B; refs. 2, 10, 11, 22, 24, 33), and thus I-band titin stiffness is too low for the above functions at physiological SL, unless it gets much larger during contraction.The mechanical definition of the I-band titin in situ in the active half-sarcomere is hampered by the presence of the in-parallel array of myosin motors with a stiffness that is more than one order of magnitude larger than titin stiffness (34). Here, we use para-nitro-blebbistatin (PNB; ref. 35) to inhibit actin–myosin interaction during tetanic stimulation of a frog muscle cell. In addition, 20 μM PNB suppresses in vitro actin-triggered ATPase activity of frog muscle myosin S1 and heavy meromyosin (HMM) (SI Appendix, Materials and Methods and Fig. S2 A and B) and the mechanical response of the muscle cell to tetanic stimulation (SI Appendix, Fig. S2 C–E), maintaining the motors in the OFF-state conformation, in which they lie tilted back on the surface of the thick filament (Fig. 1C and SI Appendix, Fig. S3) (4, 36). Previous studies noted that blebbistatin does not fully suppress the mechanical response and maintain the motor OFF-state upon Ca²⁺ activation in skinned rabbit psoas fibers (32, 37). This is likely a consequence of either the lower inhibitory power of blebbistatin as compared to PNB (SI Appendix, Fig. S2 A and B) or intrinsic limits of skinned preparations to fully preserve the motor OFF-structure (27, 38).Here, we used sarcomere-level mechanics and small-angle X-ray fiber diffraction to determine the titin-dependent mechanical and structural responses to a stepwise increase in load imposed on the muscle cell under PNB-inhibitory conditions. Length changes in units of nanometer per half-sarcomere (hereinafter referred to as nm) were measured with a striation follower in a population of ~500 sarcomeres. We discovered that upon stimulation at physiological SL, titin in the I-band switches from the OFF-state characterized by large extensibility to the ON-state in which it exhibits rectifying properties, allowing free shortening, while opposing stretching with a viscosity coefficient three orders of magnitude larger that underpins an effective stiffness of 3 pN nm⁻¹. With the I-band titin in the ON-state, the periodic interactions between A-band titin and myosin motors are able to activate the thick filament by perturbing the resting disposition of motors on the surface of the thick filament in a load-dependent manner and biasing them toward the sixfold rotational symmetry of the thin filaments in the myofilament lattice.