Protein–lipid interactions in membrane trafficking at the Golgi complex

AbstractThe integrated interplay between proteins and lipids drives many key cellular processes, such as signal transduction, cytoskeleton remodelling and membrane trafficking. The last of these, membrane trafficking, has the Golgi complex as its central station. Not only does this organelle orchestrates the biosynthesis, transport and intracellular distribution of many proteins and lipids, but also its own function and structure is dictated by intimate functional and physical relationships between protein-based and lipid-based machineries. These machineries are involved in the control of the fundamental events that govern membrane traffic, such as in the budding, fission and fusion of transport intermediates, in the regulation of the shape and geometry of the Golgi membranes themselves, and, finally, in the generation of “signals” that can have local actions in the secretory system, or that may affect other cellular systems. Lipid–protein interactions rely on the abilities of certain protein domains to recognize specific lipids. These interactions are mediated, in particular, through the headgroups of the phospholipids, although a few of these protein domains are able to specifically interact with the phospholipid acyl chains. Recent evidence also indicates that some proteins and/or protein domains are more sensitive to the physical environment of the membrane bilayer (such as its curvature) than to its chemical composition

Exploring the low temperature tempering range of low alloy quenched and tempered steels

Abstract It is well known that quenched and tempered alloy steel components with ultimate tensile strength in excess of 1400 MPa are seldom employed as mechanical components, due to their not adequate ductility, as ascertained by multiple researches performed during World War II and soon after. Nevertheless, use of low temperature tempered steels in some niche applications, as well as researches performed on surface heat treated high carbon steels and on their behavior upon tempering in the vicinity of 200°C have stemmed into renewed interest in quenched and low temperature tempered low alloy steels. Application to 36NiCrMo16 steel bars is examined here, by means of tensile and hardness tests and fractographic and metallographic examinations after quenching and tempering in the 160 to 440 °C temperature range

Optimal tuning of adaptive augmenting controller for launch vehicles in atmospheric flight

In this Note, two novel and effective tuning methodologies for an adaptive augmenting control (AAC) system, realized to consistently improve performance and robustness of a standard launch vehicle single-axis attitude controller in atmospheric flight, have been presented. To this end, a methodology for AAC parameter tuning is presented where a robust design optimization (RDO) problem is formulated, and the goal is to maximize a statistical metric that describes FCS performance measured over a set of representative simulations of LV flight. In more detail, adaptive law parameters are tuned with the aim of minimizing attitude error and traversal aerodynamic loads. As major advantages, the occurrence of Loss of vehicle (LOV) events and the issues and burden of the manual trial-and-error procedures currently adopted for the design of the adaption law may be reduced

Development of a multi-phase dynamic ray-tracing code

We here propose a method for rapid, high-frequency seismogram generation that makes use of an algorithm to automatically generate an exhau- stive set of seismic phases that produce an appreciable amplitude on the sei- smogram. The method uses a hierarchical order of rays and seismic phases generation, taking into account some existence constraints for a ray-path and some physical constraints. To compute synthetic seismograms, the COMRAD code (from the Italian: “COdice Multifase per il RAy-tracing Dinamico”) uses as its core a dynamic ray-tracing code. To validate the code, we have computed in a layered medium synthetic seismograms using both COMRAD and a code which computes the complete wavefield by the discrete wavenumber method. The seismograms are compared according to a time-frequency misfit criteria based on the continuous wavelet transform of the signals. The comparison shows that the ray-theory seismogram is enough complete and moreover, the time for the computing of the synthetics using the COMRAD code (truncating the ray series at the 10th generation) is 3-4-fold less than that needed for the Axitra code (to a frequency of 25 Hz)

Single axis pointing for underactuated spacecraft with a residual angular momentum

The problem of aiming a generic body-fixed axis along an inertially fixed direction is dealt with for an underactuated spacecraft in the presence of a non-zero residual angular momentum, when only two reaction wheels can exchange angular momentum with the spacecraft platform. An analytical condition for the feasibility of the desired pointing is derived first, together with a closed-form solution for the corresponding attitude with zero platform angular rate. A nonlinear controller is then developed in the framework of singular perturbation theory, enforcing a two-timescale response to the system. Convergence to the desired attitude, when the pointing direction falls within admissible limits, is then proved for rest-to-rest maneuvers and randomly generated initial tumbling conditions for a configuration representative of a small-size satellite

A new spirometry-based algorithm to predict occupational pulmonary restrictive impairment

Background Spirometry is often included in workplace-based respiratory surveillance programmes but its performance in the identification of restrictive lung disease is poor, especially when the prevalence of this condition is low in the tested population. Aims To improve the specificity (Sp) and positive predictive value (PPV) of current spirometry-based algorithms in the diagnosis of restrictive pulmonary impairment in the workplace and to reduce the proportion of false positives findings and, as a result, unnecessary referrals for lung volume measurements. Methods We re-analysed two studies of hospital patients, respectively used to derive and validate a recommended spirometry-based algorithm [forced vital capacity (FVC) < 85% predicted and forced expiratory volume in 1 s (FEV1)/FVC > 55%] for the recognition of restrictive pulmonary impairment. We used true lung restrictive cases as a reference standard in 2×2 contingency tables to estimate sensitivity (Sn), Sp and PPV and negative predictive values for each diagnostic cut-off. We simulated a working population aged <65 years and with a disease prevalence ranging 1–10% and compared our best algorithm with those previously reported using receiver operating characteristic curves. Results There were 376 patients available from the two studies for inclusion. Our best algorithm (FVC < 70% predicted and FEV1/FVC ≥ 70%) achieved the highest Sp (96%) and PPV (67 and 15% for a disease prevalence of 10 and 1%, respectively) with the lowest proportion of false positives (4%); its high Sn (71%) predicted the highest proportion of correctly classified restrictive cases (91%). Conclusions Our new spirometry-based algorithm may be adopted to accurately exclude pulmonary restriction and to possibly reduce unnecessary lung volume testing in an occupational health setting

Post-mortem diagnosis of intravascular large B-cell lymphoma

Intravascular large B-cell lymphoma (IVLBCL) is a rare (<1%), typically aggressive extranodal variant of mature non-Hodgkin B-cell lymphoma. IVLBCL is characterized by malignant lymphoid cells lodged within blood vessels, particularly capillary channels. Herein, we present a case of a 50-year-old man with a history of myeloradiculitis (∼1 year) and paraparesis requiring hospitalization. During the course of his hospital stay, computed tomography (CT), magnetic resonance imaging, CT-positron emission tomography, and biopsy failed to establish a diagnosis. The patient died 2 months later from bilateral pneumonia. Postmortem examination was undertaken to determine the cause of death. Histologic sections of the patient’s brain, heart, lung, and liver showed aggregates of highly atypical cells bearing enlarged, pleomorphic, and hyperchromatic nuclei. Strong intravascular positivity for CD45 and CD20 markers indicated the cells were of B-cell origin, supporting a diagnosis of IVLBCL