A microfluidic counter current dialysis device for size based purification of DNA is described. The device consists of two polydimethylsiloxane (PDMS) channels separated by a track etched polycarbonate membrane with a 50 nm pore size. Recovery of fluorescein across the membrane was compared with 10 and 80 nucleotide (nt) ssDNA ...

ATP synthases are the primary source of ATP in all living cells. To catalyze ATP synthesis, these membrane-associated complexes use a rotary mechanism powered by the transmembrane diffusion of ions down a concentration gradient. ATP synthases are assumed to be driven either by H(+) or Na(+), reflecting distinct structural motifs ...

Burow's solution, comprising aluminum sulfate and acetic acid, is an otic drug formulation applied to the tympanic cavity. We characterized the relationship between the auditory brain stem response (ABR) thresholds and the area of the capillary basement membrane anionic sites in the stria vascularis after the application of Burow's solution. ...

Purpose: To describe a case of a patient with inferior Descemet membrane detachment that resolved after injection of small air bubble and supine positioning. Methods: A patient presented two weeks after cataract surgery with inferior persistent corneal edema. A Descemet membrane detachment involving the inferior cornea was revealed. Injection of ...

To identify factors related to the decrease in core body temperature after deflation of a pneumatic tourniquet during unilateral knee surgery under general anaesthesia. This observational study recruited 30 patients scheduled for arthroscopic surgery (group A) and 30 patients scheduled for open surgery (group O). Intraoperative oesophageal temperature was measured ...

Research efforts during the last decade have deciphered the basic molecular mechanisms governing mitochondrial fusion and fission. We now know that in mammalian cells mitochondrial fission is mediated by the large GTPase dynamin-related protein 1 (Drp1) acting in concert with outer mitochondrial membrane (OMM) proteins such as Fis1, Mff, and ...

Breakdown of mammalian cerebral cell membrane phospholipids releases phosphorylated polar head groups from the sn-3 phospholipid position, including phosphorylcholine and phosphorylethanolamine. Glycerophosphorylcholine and glycerophosphorylethanolamine are on their catabolic pathways and have been assigned to the phosphodiester narrow resonance obtained from 31-phosphorus neurospectroscopy, accounting for approximately 38% of the overall signal; ...

The inner membrane of the ATP-producing organelles of endosymbiotic origin, mitochondria, has long been considered to be poorly permeable to cations and anions, since the strict control of inner mitochondrial membrane permeability is crucial for efficient ATP synthesis. Over the past 30 years, however, it has become clear that various ion ...

In this contribution, we report in vitro folding of the archaebacterial voltage-gated K(+) channel, K(v)AP. We show that in vitro folding of the K(v)AP channel from the extensively unfolded state requires lipid vesicles and that the refolded channel is biochemically and functionally similar to the native channel. The in vitro ...

CNS injury is often localized but can be followed by more widespread secondary degenerative events that usually result in greater functional loss. Using a partial transection model in rat optic nerve (ON). we recently demonstrated in vivo increases in the oxidative stress-associated enzyme MnSOD 5 min after injury. However, mechanisms ...

Central hyperthermia is characterized by the rapid onset of high body temperature, marked temperature fluctuation, and high mortality. It is usually associated with brainstem damage caused by direct destruction or indirect compression. Herein, we report a 79-year-old man with bilateral paramedian mesencephalothalamic infarction presenting with hyperthermia. On admission, his body ...

Neuronal differentiation is characterized by neuritogenesis and neurite outgrowth, processes, which are critically dependent on membrane biosynthesis, and therefore, on the expression and regulation of enzymes involved in phospholipid biosynthesis. During the last decade a great effort was made to clarify where membrane lipids are synthesized, how the newly synthesized ...

Objective. The goal of this study was to analyze the prevalence of tympanic membrane rupture in the survivors of the London bombings of July 2005 and to assess whether tympanic membrane rupture provides a useful biomarker for underlying primary blast injuries. Study Design. Cross-sectional study. Subjects and Methods. Survivors of ...

Mammalian hibernation consists of periods of depressed metabolism and reduced body temperature called "torpor" that are interspersed by normothermic arousal periods. Numerous cellular processes are halted during torpor, including transcription, translation and ion homeostasis. Hibernators are able to survive long periods of low blood flow and body temperature followed by ...

Fish exposed to elevated water CO(2) experience a rapid increase in blood CO(2) levels (hypercapnia), resulting in acidification of both intra- and extra-cellular compartments. While the mechanisms associated with extracellular pH regulation have been well explored, much less is known about intracellular pH (pH(i)) regulation. There is great interest in ...

Antimicrobial photodynamic therapy (APDT) is a novel technique to treat local infections. Previously we reported that the attachment of chlorin(e6) to polyethylenimine (PEI) polymers to form PEI-ce6 conjugates is an effective way to improve ce6 PDT activity against bacteria. The aim of this work was to explore how the polymer ...

A mutant form of the copper/zinc superoxide dismutase (SOD1) protein is found in some patients with amyotrophic lateral sclerosis (ALS). Alteration of the activity of this antioxidant enzyme leads to an oxidative stress imbalance, which damages the structure of lipids and proteins in the CNS. Using fluorescence spectroscopy, we monitored ...

Development of nonfouling membranes to prevent nonspecific protein adsorption and platelet adhesion is critical for many biomedical applications. It is always a challenge to control the surface graft copolymerization of a highly polar monomer from the highly hydrophobic surface of a fluoropolymer membrane. In this work, the blood compatibility of ...

A 57 year-old man developed broad-based unsteady gait and memory loss over a period of one year. On admission, bradykinesia and impairment of postural reflex were evident. Mini-mental state examination scored 27/30. Urinary control was normal. MRI revealed symmetric dilatation of lateral and 3rd ventricles, but the 4th ventricle appeared ...

We aimed to show the significance of the anterior pontine membrane as a determining structure between the subdural and subarachnoid space in the clival region. MATERIAL and Five adult cadaver heads and five cerebral hemispheres were used. The skull vault and hemipheres were removed by sectioning through the pontomesencephalic junction. ...

The heart is a continually active pulsatile fluid pump. It generates appropriate forces by precisely timed and spaced engagement of its contractile machinery. Largely, it makes its own control signals, the most crucial of which are precisely timed and spaced fluxes of ions across the sarcolemma, achieved by the timely ...

A new acid sensitive nanocarrier based on lipid core micelles has been investigated for tumor targeted drug delivery. Sulfadimethoxine-PEG-phospholipid unimer (SD-PEG-DSPE) was designed to endow micelles with pH responsiveness in the physiopathologic range. The unimer was synthesized according to a two-step procedure. Potentiometric analysis showed that SD-PEG-DSPE has pK(a) of ...

Investigating the structural and mechanical properties of lipid bilayer membrane systems is vital in elucidating their biological function. One route to directly correlate the morphology of phase-segregated membranes with their indentation and rupture mechanics is the collection of atomic force microscopy (AFM) force maps. These force maps, while containing rich ...

We report a novel and facile method for measuring edge tensions of lipid membranes. The approach is based on electroporation of giant unilamellar vesicles and analysis of the pore closure dynamics. We applied this method to evaluate the edge tension in membranes with four different compositions: egg phosphatidylcholine (eggPC), dioleoylphosphatidylcholine ...

A semiquantitative theory to describe the adhesion mechanism between an elastic membrane and a solid substrate (or another membrane) was developed. Since the membrane bending deformation requires a relatively small energy cost, thermally excited fluctuations may give rise to a local protrusion connecting the membrane to the substrate. This transient ...

Semiconductor micro- and nanotubes can be formed by strain-induced self-rolling of membranes. The effect of geometrical dimensions on the self-rolling behavior of epitaxial mismatch-strained In(x)Ga(1-x)As-GaAs membranes are systematically studied both experimentally and theoretically using the finite element method. The final rolling direction depends on the length and width of the ...

Mechanical properties of ultrathin membranes consisting of one layer, two overlapped layers, and three overlapped layers of graphene oxide platelets were investigated by atomic force microscopy (AFM) imaging in contact mode. In order to evaluate both the elastic modulus and prestress of thin membranes, the AFM measurement was combined with ...

Collections of motors dynamically organize to extract membrane tubes. These tubes grow but often pause or change direction as they traverse an underlying microtubule (MT) network. In vitro, membrane tubes also stall: they stop growing in length despite a large group of motors available at the tip to pull them ...

Highly monodisperse poly(N-isopropylacrylamide), PNiPAM, microgels were prepared by the conventional radical polymerization of NiPAM in the presence of dimethylamino ethyl methacrylate (DMAEMA) monomers at various concentrations. The effect of DMAEMA on the polymerization of PNiPAM microgels was examined at constant initiator (V50) and cross-linker (MBA) concentrations. The presence of DMAEMA ...

Membrane protrusion is a mechanochemical process of active membrane deformation driven by actin polymerization. Previously, Brownian ratchet (BR) was modeled on the basis of the underlying molecular mechanism. However, because the BR requires a priori load that cannot be determined without information of the cell shape, it cannot be effective ...

We present temperature-dependent atomic force microscope (AFM) measurements in force-distance mode of confined 1-dodecanol. Upon approach of the AFM-tip toward the highly oriented pyrolytic graphite (HOPG) surface, the final liquid film--only a few nanometers thin--is squeezed out in discrete layers. We find that both the force needed to squeeze out ...

Design of molecules for self-assembled mesoscopic structures with specific functions is an important and interesting challenge that spans across disciplines such as nanosciences. A closed lipid membrane is a good example of a self-assembled mesostructure. In this study, we developed controllable membrane formation by making a subtle change at the ...

The dissipative tip-sample interactions are measured by dynamic force spectroscopy for silicon tips on NaCl(001) in ultrahigh vacuum in the attractive and repulsive force regimes. Force and dissipation versus distance curves were obtained for different sample temperatures ranging from 35 to 285 K. Detailed comparison in different distance regimes shows ...

Living cells maintain a huge transmembrane electric field across their membranes. This electric field exerts a force on the membrane because the membrane surfaces are highly charged. We have measured electromechanical force generation by cell membranes using optically trapped beads to detach the plasma membrane from the cytoskeleton and form ...

We propose a method of achieving large temperature T sensitivity in the Casimir force that involves measuring the stable separation between dielectric objects immersed in a fluid. We study the Casimir force between slabs and spheres using realistic material models, and find large >2  nm/K variations in their stable separations (hundreds ...

The paper describes immobilization methods of bacteriophage P22 and tailspike gp9 proteins isolated from P22 on atomic force microscope (AFM) probes. The paper also reports single molecule force spectroscopy (SMFS) using AFM of the immobilized P22 (or gp9) interactions with substrate-supported O-antigenic lipopolysaccharides (LPS) bilayers. LPS covers the outer membrane ...

The cationic amphiphilic antimicrobial peptide gramicidin S (GS) is an effective antibiotic. Its applicability is however restricted to topical infections due to its hemolytic activity. In this study, the process of GS induced hemolysis was investigated in detail for the first time. The morphological changes of red blood cells (RBCs) ...

Membrane tethers or nanotubes play a critical role in a variety of cellular and subcellular processes such as leukocyte rolling and intercellular mass transport. The current constitutive equations that describe the relationship between the pulling force and the tether velocity during tether extraction have serious limitations. In this article, we ...

Kites offer considerable potential as wind speed sensors--a role distinct from their traditional use as instrument-carrying platforms. In the sensor role, wind speed is measured by kite-line tension. A kite tether line tension meter is described here, using strain gauges mounted on an aluminum ring in a Wheatstone bridge electronic ...

There is uncertainty about the response of the climate system to future trajectories of radiative forcing. To quantify this uncertainty we conducted face-to-face interviews with 14 leading climate scientists, using formal methods of expert elicitation. We structured the interviews around three scenarios of radiative forcing stabilizing at different levels. All ...

The surface tensions of pure ionic liquid, 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]), and binary mixtures of [BMIM][SCN] with alcohols (1-butanol, 1-pentanol, 1-hexanol) have been measured at atmospheric pressure at five temperatures in the range from 298.15 to 328.15 K. These measurements have been provided to complete information of the influence of temperature ...

Although Casimir forces are inseparable from their fluctuations, little is known about these fluctuations in soft matter systems. We use the membrane stress tensor to study the fluctuations of the membrane-mediated Casimir-like force. This method enables us to recover the Casimir force between two inclusions and to calculate its variance. ...

In this work the influence of the carbon source concentration, of the type and concentration of the nitrogen source and of the cultivation conditions (temperature, aeration and agitation speed) in mineral medium formulated with glycerol was studied for biosurfactant production by Pseudomonas aeruginosa UCP0992. The kinetics of microorganism growth and ...

The theoretical and experimental description of fluid phase endocytosis (FPE) requires an asymmetry in phospholipid number between the two leaflets of the cell membrane, which provides the biomechanical torque needed to generate membrane budding. Although the motor force behind FPE is defined, its kinetic has yet to be determined. Based ...

We investigate the properties of membranes under tension by Monte Carlo simulations of a generic coarse-grained model for lipid bilayers. We give a comprising overview of the behavior of several membrane characteristics, such as the area per lipid, the monolayer overlap, the nematic order, and pressure profiles. Both the low-temperature ...

The electrical properties of the cellular membrane are important for ion transport across cells and electrophysiology. Plasma membranes also resist bending and stretching, and mechanical properties of the membrane influence cell shape and forces in membrane tethers pulled from cells. There exists a coupling between the electrical and mechanical properties ...

Using analytical calculations and computer simulations, we consider both the lateral diffusion of a membrane protein and the fluctuation spectrum of the membrane in which the protein is embedded. The membrane protein interacts with the membrane shape through its spontaneous curvature and bending rigidity. The lateral motion of the protein ...

Cases of long-term deformation of fused silica flats are reported. The phenomenon is detected at the scale of the nanometer, and exhibits a time constant of the order of 9 years. The observed deformation appears related to gravity and constraints, but a change of physical properties locally resulting in non-homothetic ...

We have been able to design model filled rubbers with exactly the same chemical structure but different filler arrangements. From these model systems, we show that the particle arrangement in the elastomeric matrix controls the strain softening at small strain amplitude known as the Payne effect, as well as the ...

A versatile model system to study membrane-membrane interactions in great detail is introduced. Based on colloidal probe microscopy with membrane covered spherical probes attached to tip-less cantilevers the interaction forces and adhesion energies are quantified down to single molecule resolution. Two opposing membranes equipped with ligands on one side and ...