Amphiphilic drug interactions with model cellular membranes are influenced by lipid chain-melting temperature

Small-molecule amphiphilic species such as many drug molecules frequently exhibit low-to-negligible aqueous solubility, and generally have no identified transport proteins assisting their distribution, yet are able to rapidly penetrate significant distances into patient tissue and even cross the blood–brain barrier. Previous work has identified a mechanism of translocation driven by acid-catalysed lipid hydrolysis of biological membranes, a process which is catalysed by the presence of cationic amphiphilic drug molecules. In this study, the interactions of raclopride, a model amphiphilic drug, were investigated with mixtures of biologically relevant lipids across a range of compositions, revealing the influence of the chain-melting temperature of the lipids upon the rate of acyl hydrolysis.     

The Urban Crisis

Advocacy and social responsibility of the profession, of the ACSA and the elements of the new curriculum in architectural education.     

Alterations in gap junction connexin43/connexin45 ratio mediate a transition from quiescence to excitation in a mathematical model of the myometrium

The smooth muscle cells of the uterus contract in unison during delivery. These cells achieve coordinated activity via electrical connections called gap junctions which consist of aggregated connexin proteins such as connexin43 and connexin45. The density of gap junctions governs the excitability of the myometrium (among other factors). An increase in gap junction density occurs immediately prior to parturition. We extend a mathematical model of the myometrium by incorporating the voltage-dependence of gap junctions that has been demonstrated in the experimental literature. Two functional subtypes exist, corresponding to systems with predominantly connexin43 and predominantly connexin45, respectively. Our simulation results indicate that the gap junction protein connexin45 acts as a negative modulator of uterine excitability, and hence, activity. A network with a higher proportion of connexin45 relative to connexin43 is unable to excite every cell. Connexin45 has much more rapid gating kinetics than connexin43 which we show limits the maximum duration of a local burst of activity. We propose that this effect regulates the degree of synchronous excitation attained during a contraction. Our results support the hypothesis that as labour approaches, connexin45 is downregulated to allow action potentials to spread more readily through the myometrium.     

Photobleaching with phloxine B sensitizer to reduce food matrix interference for detection of Escherichia coli serotype O157:H7 in fresh spinach by flow cytometry

A flow cytometric method (RAPID-B™) with detection sensitivity of one viable cell of Escherichia coli serotype O157:H7 in fresh spinach (Spinacia oleracea) was developed and evaluated. The major impediment to achieving this performance was mistaking autofluorescing spinach particles for tagged target cells. Following a 5 h non-selective enrichment, artificially inoculated samples were photobleached, using phloxine B as a photosensitizer. Samples were centrifuged at high speed to concentrate target cells, then gradient centrifuged to separate them from matrix debris. In external laboratory experiments, RAPID-B and the reference method both correctly detected E. coli O157:H7 at inoculations of ca. 15 cells. In a follow-up study, after 4 cell inoculations of positives and 6 h enrichment, RAPID-B correctly identified 92% of 25 samples. The RAPID-B method limit of detection (LOD) was one cell in 25 g. It proved superior to the reference method (which incorporated real time-PCR, selective enrichment, and culture plating elements) in accuracy and speed.     

Experimental Investigation of the Properties of Lime-Based Plaster-Containing PCM for Enhancing the Heat-Storage Capacity of Building Envelopes

Experimental analysis of a wide range of properties of a lightweight plaster which should enhance the heat-storage capacity of building envelopes is presented. The basic physical characteristics, namely, the bulk density, matrix density, total open porosity, and pore-size distribution are measured at first. Then, the compressive strength is determined for an assessment of mechanical performance of the plaster. The thermal conductivity and thermal diffusivity are studied using an impulse technique. Differential scanning calorimetry measurements are performed as well, in order to identify the temperature range and latent heat of the phase change and to determine the specific heat capacity as a function of temperature. Durability properties are assessed using the measurement of the water absorption coefficient and sorption and desorption isotherms. The experimental results indicate a good capability of the designed plaster to moderate effectively the interior climate of buildings.     

Electrochemical detection of 14 common munitions constituents

Electrochemical detections of 14 munitions constituents (MCs) listed on the Environmental Protection Agency hazardous waste list were examined using square wave voltammetry. Of the MCs that showed peak resolution in the scanned range, the reduction potential, limit of detection and limit of quantitation are reported here. The MCs tested are in three groups: nitrobenzenes, nitrotoluenes, and other nitro-aromatics: tetryl, HMX, and RDX. There was a correlation between peak resolution and the number of nitro groups for the nitrobenzenes and nitrotoluenes. The nitro group distance from the methyl for the nitrotoluenes with two nitro groups showed some correlation to the ability to detect as well. Some mixture experiments were conducted in which MCs with three and two nitro groups were detected simultaneously. While tetryl readily displayed two peaks, RDX and HMX did not show such clear peak resolution.