Diffusion of Short Semiflexible DNA Polymer Chains in Strong and Moderate Confinement.

In many technological applications, DNA is confined within nanoenvironments that are smaller than the size of the unconfined polymer in solution. However, the dependence of the diffusion coefficient on molecular weight and characteristic confinement dimension remains poorly understood in this regime. Here, convex lens-induced confinement (CLiC) was leveraged to examine how the diffusion of short DNA fragments varied as a function of slit height by using single-molecule fluorescence tracking microscopy.

Enhanced Facilitated Diffusion of Membrane-Associating Proteins under Symmetric Confinement.

The facilitated surface diffusion of transiently adsorbing molecules in a planar confined microenvironment (i.e., slit-like confinement) is highly relevant to biological phenomena, such as extracellular signaling, as well as numerous biotechnology systems.

Vegetation plot and trait data from phonolitic and basaltic rocks on La Palma (Canary Islands, Spain).

Geodiversity promotes biodiversity by increasing habitat heterogeneity. In times of a global biodiversity decline, data about diversity on such geological elements gains importance, also regarding conservation and restoration. In the Canary Islands, phonolitic rocks are geological elements of volcanic origin that represent additional habitat for species.

Single molecule characterization of anomalous transport in a thin, anisotropic film.

The diffusion of small, charged molecules incorporated in an anisotropic polyelectrolyte multilayer (PEM) was tracked in three dimensions by combining single-molecule fluorescence localization (to characterize lateral diffusion) with Förster resonance energy transfer (FRET) between diffusing molecules and the supporting surface (to measure diffusion in the surface-normal direction). Analysis of the surface-normal diffusion required model-based statistical analysis to account for the inherently noisy FRET signal. Combining these distinct single-molecule methods, which are inherently sensitive to different length-scales, permitted simultaneous characterization of severely anisotropic diffusion, which was more than three orders of magnitude slower in the surface-normal direction.

Single-Molecule Observations Provide Mechanistic Insights into Bimolecular Knoevenagel Amino Catalysis.

While single-molecule (SM) methods have provided new insights to various catalytic processes, bimolecular reactions have been particularly challenging to study. Here, the fluorogenic Knoevenagel condensation of an aromatic aldehyde with methyl cyanoacetate promoted by surface-immobilized piperazine is quantitatively characterized using super-resolution fluorescence imaging and stochastic analysis using hidden Markov modeling (HMM). Notably, the SM results suggest that the reaction follows the iminium intermediate pathway before the formation of a fluorescent product with intramolecular charge-transfer character.

Polyelectrolyte Multilayers Enhance the Dry Storage and pH Stability of Physically Entrapped Enzymes.

Polyelectrolyte multilayers (PEMs) are attractive materials for immobilizing enzymes due to their unique ionic environment, which can prevent unfolding. Here, we demonstrated that the stability to dry storage and elevated pH were significantly enhanced when negatively charged nitroreductase (NfsB) was embedded in a PEM by depositing alternating layers of the enzyme and polycation (PC) onto porous silica particles. The PC strength (i.

Changes in microbubble dynamics upon adhesion to a solid surface.

The interaction between an acoustically driven microbubble and a surface is of interest for a variety of applications, such as ultrasound imaging and therapy. Prior investigations have mainly focused on acoustic effects of a rigid boundary, where it was generally observed that the wall increases inertia and reduces the microbubble resonance frequency. Here we investigate the response of a lipid-coated microbubble adherent to a rigid wall.

Approved and emerging PI3K inhibitors for the treatment of chronic lymphocytic leukemia and non-Hodgkin lymphoma.

Introduction: PI3K inhibition with idelalisib (at that time CAL-101) was at the forefront of the development of molecularly targeted therapies in Chronic Lymphocytic Leukemia (CLL)/Small Lymphocytic Leukemia (SLL) and follicular lymphoma. However, after initial approval, subsequent trials identified specific immune-mediated and infectious toxicity that led to a reduced use and stopped the further development of this agent. PI3K inhibition as a treatment paradigm fell out of favor compared to other developments such as BTK or BCL2 inhibitors.

Reduced Enzyme Dynamics upon Multipoint Covalent Immobilization Leads to Stability-Activity Trade-off.

The successful incorporation of enzymes into materials through multipoint covalent immobilization (MPCI) has served as the foundation for numerous advances in diverse fields, including biocatalysis, biosensing, and chemical weapons defense. Despite this success, a mechanistic understanding of the impact of this approach on enzyme stability has remained elusive, which is critical for realizing the full potential of MPCI. Here, we showed that the stabilization of lipase upon MPCI to polymer brush surfaces resulted from the rigidification of the enzyme with an increase in the number of enzyme-brush attachments.

Surface-Templated Nanobubbles Protect Proteins from Surface-Mediated Denaturation.

In this Letter, we report that surface-bound nanobubbles reduce protein denaturation on methylated glass by irreversible protein shell formation. Single-molecule total internal reflection fluorescence (SM-TIRF) microscopy was combined with intramolecular Förster resonance energy transfer (FRET) to study the conformational dynamics of nitroreductase (NfsB) on nanobubble-laden methylated glass surfaces, using reflection brightfield microscopy to register nanobubble locations with NfsB adsorption. First, NfsB adsorbed irreversibly to nanobubbles with no apparent desorption after 5 h.

Emerging Attractor in Wavy Poiseuille Flows Triggers Sorting of Biological Cells.

Microflows constitute an important instrument to control particle dynamics. A prominent example is the sorting of biological cells, which relies on the ability of deformable cells to move transversely to flow lines. A classic result is that soft microparticles migrate in flows through straight microchannels to an attractor at their center.

Standalone interferometry-based calibration of convex lens-induced confinement microscopy with nanoscale accuracy.

Strongly confined environments (confined dimensions between 1-100 nm) represent unique challenges and opportunities for understanding and manipulating molecular behavior due to the significant effects of electric double layers, high surface-area to volume ratios, and other phenomena at the nanoscale. Convex Lens-induced Confinement (CLiC) can be used to analyze the dynamics of individual molecules or particles confined in a planar slit geometry with continuously varying gap thickness. We describe an interferometry-based method for precise measurement of the slit pore geometry.

Complex Salt Dependence of Polymer Diffusion in Polyelectrolyte Multilayers.

Polyelectrolyte multilayers (PEMs) have significant potential in many technologies, yet the dynamics of the constituent polymer chains remains poorly understood. We used total internal reflection fluorescence microscopy to observe microscopic single-molecule transport of fluorescently labeled poly-l-lysine (PLL) diffusing within the bulk of a PEM composed of PLL and poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) when exposed to NaCl solutions ranging in concentration from 0 to 2 M. Statistical analysis of PLL trajectories revealed motion that was nonergodic, subdiffusive, and temporally anticorrelated under all conditions.

Cetuximab monotherapy and cetuximab plus capecitabine as first-line treatment in older patients with RAS- and BRAF wild-type metastatic colorectal cancer. Results of the multicenter phase II trial SAKK 41/10.

Introduction: While the anti-VEGF antibody bevacizumab was studied repeatedly as part of low-intensity regimens in less fit elderly patients with metastatic colorectal cancer (mCRC), anti-EGFR antibodies as upfront treatment modality have been scarcely investigated.

Material And Methods: In SAKK 41/10, the benefit of cetuximab, either alone or in combination with capecitabine, was evaluated in vulnerable elderly patients with RAS/BRAF-wild-type mCRC.

Results And Discussion: The trial was stopped prematurely due to slow accrual after the inclusion of 24 patients (11 in the monotherapy arm, 13 in the combination arm).

Correlating Structural and Functional Heterogeneity of Immobilized Enzymes.

Many nanobiotechnology applications rely on stable and efficient integration of functional biomacromolecules with synthetic nanomaterials. Unfortunately, the reasons for the ubiquitous loss of activity of immobilized enzymes remain poorly understood due to the difficulty in distinguishing between distinct molecular-level mechanisms. Here, we employ complementary single-molecule fluorescence methods that independently measure the impact of immobilization on the structure and function ( i.

Stabilization of Immobilized Enzymes via the Chaperone-Like Activity of Mixed Lipid Bilayers.

Biomimetic lipid bilayers represent intriguing materials for enzyme immobilization, which is critical for many biotechnological applications. Here, through the creation of mixed lipid bilayers, the retention of immobilized enzyme structures and catalytic activity are dramatically enhanced. The enhancement in the retention of enzyme structures, which correlated with an increase in enzyme activity, is observed using dynamic single-molecule (SM) fluorescence methods.

Grafting Density Impacts Local Nanoscale Hydrophobicity in Poly(ethylene glycol) Brushes.

Accumulated single-molecule observations of a fluorescent solvatochromic probe molecule were found to provide detailed local information about nanoscale hydrophobicity in polymer brushes. Using this approach, we showed that local hydrophobicity in poly(ethylene glycol) (PEG) brushes was spatially heterogeneous and increased with the surface grafting density of the polymer chains. These findings may provide an explanation for prior observations of the denaturation of surface-adsorbed proteins on PEG brushes with high grafting densities, which is believed to influence protein-mediated cell-surface interactions.

Chronic Lymphocytic Leukemia with Mutated IGHV4-34 Receptors: Shared and Distinct Immunogenetic Features and Clinical Outcomes.

We sought to investigate whether B cell receptor immunoglobulin (BcR IG) stereotypy is associated with particular clinicobiological features among chronic lymphocytic leukemia (CLL) patients expressing mutated BcR IG (M-CLL) encoded by the IGHV4-34 gene, and also ascertain whether these associations could refine prognostication. In a series of 19,907 CLL cases with available immunogenetic information, we identified 339 IGHV4-34-expressing cases assigned to one of the four largest stereotyped M-CLL subsets, namely subsets #4, #16, #29 and #201, and investigated in detail their clinicobiological characteristics and disease outcomes. We identified shared and subset-specific patterns of somatic hypermutation (SHM) among patients assigned to these subsets.

Analyzing refractive index profiles of confined fluids by interferometry part II: Multilayer and asymmetric systems.

Methods for determining the substrate properties and the optical thickness of thin films or any variation in the refractive index of a fluid or film near a surface for unknown 5-layer symmetric and 3-layer asymmetric interferometers are presented. Both systems can be fully resolved without any known layer properties and without contact or confining the films. The method was tested using realistic simulated interferometer data, and was found to consistently yield accurate values for all desired properties.

Density and Phase State of a Confined Nonpolar Fluid.

Measurements of the mean refractive index of a spherelike nonpolar fluid, octamethytetracylclosiloxane (OMCTS), confined between mica sheets, demonstrate direct and conclusive experimental evidence of the absence of a first-order liquid-to-solid phase transition in the fluid when confined, which has been suggested to occur from previous experimental and simulation results. The results also show that the density remains constant throughout confinement, and that the fluid is incompressible. This, along with the observation of very large increases (many orders of magnitude) in viscosity during confinement from the literature, demonstrate that the molecular motion is limited by the confining wall and not the molecular packing.

Analyzing refractive index profiles of confined fluids by interferometry.

This work describes an interferometry data analysis method for determining the optical thickness of thin films or any variation in the refractive index of a fluid or film near a surface. In particular, the method described is applied to the analysis of interferometry data taken with a surface force apparatus (SFA). The technique does not require contacting or confining the fluid or film.

Thickness and refractive index of DPPC and DPPE monolayers by multiple-beam interferometry.

The thickness and refractive index of 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayers Langmuir--Blodgett (LB) deposited on mica were measured in dry air and bulk water using multiple-beam interferometry (MBI). Measurements of thickness using atomic force microscopy (AFM) of identical monolayers, and X-ray reflectivity (XRR) of the monolayers on quartz were taken for comparison. The measurement of the properties of solid-supported monolayers in dry air allows lipid optical properties to be determined free from solvent effects.

Strain-induced optical changes in demineralized bone.

Bone "stress-whitens," becoming visibly white during mechanical loading, immediately prior to failure. Stress-whitening is known to make materials tougher by dissipating mechanical energy. A greater understanding of stress-whitening, both an optical and mechanical phenomenon, may help explain age-related increases in fracture risk that occur without changes in bone mineralization.

[The spleen in hematologic malignancies].

The spleen represents a major lymphatic and hematologic organ and, as such, is frequently involved in hematologic malignancies. Splenomegaly may constitute the first clinical sign leading to the diagnosis of a hematologic malignancy. Vice versa, the presence, or suspicion of a hematologic malignancy requires investigation of the spleen.