Molecular velocity auto-correlation of simple liquids observed by NMR MGSE method

The velocity auto-correlation spectra of simple liquids obtained by the NMR method of modulated gradient spin echo show features in the low frequency range up to a few kHz, which can be explained reasonably well by a $t^{-3/2}$ long time tail decay only for non-polar liquid toluene, while the spectra of polar liquids, such as ethanol, water and glycerol, are more congruent with the model of diffusion of particles temporarily trapped in potential wells created by their neighbors. As the method provides the spectrum averaged over ensemble of particle trajectories, the initial non-exponential decay of spin echoes is attributed to a spatial heterogeneity of molecular motion in a bulk of liquid, reflected in distribution of the echo decays for short trajectories. While at longer time intervals, and thus with longer trajectories, heterogeneity is averaged out, giving rise to a spectrum which is explained as a combination of molecular self-diffusion and eddy diffusion within the vortexes of hydrodynamic fluctuations.Comment: 8 pages, 6 figur

Rugged Single Domain Antibody Detection Elements for Bacillus anthracis Spores and Vegetative Cells

Significant efforts to develop both laboratory and field-based detection assays for an array of potential biological threats started well before the anthrax attacks of 2001 and have continued with renewed urgency following. While numerous assays and methods have been explored that are suitable for laboratory utilization, detection in the field is often complicated by requirements for functionality in austere environments, where limited cold-chain facilities exist. In an effort to overcome these assay limitations for Bacillus anthracis, one of the most recognizable threats, a series of single domain antibodies (sdAbs) were isolated from a phage display library prepared from immunized llamas. Characterization of target specificity, affinity, and thermal stability was conducted for six sdAb families isolated from rounds of selection against the bacterial spore. The protein target for all six sdAb families was determined to be the S-layer protein EA1, which is present in both vegetative cells and bacterial spores. All of the sdAbs examined exhibited a high degree of specificity for the target bacterium and its spore, with affinities in the nanomolar range, and the ability to refold into functional antigen-binding molecules following several rounds of thermal denaturation and refolding. This research demonstrates the capabilities of these sdAbs and their potential for integration into current and developing assays and biosensors

Application of In Vivo Induced Antigen Technology (IVIAT) to Bacillus anthracis

In vivo induced antigen technology (IVIAT) is an immuno-screening technique that identifies bacterial antigens expressed during infection and not during standard in vitro culturing conditions. We applied IVIAT to Bacillus anthracis and identified PagA, seven members of a N-acetylmuramoyl-L-alanine amidase autolysin family, three P60 family lipoproteins, two transporters, spore cortex lytic protein SleB, a penicillin binding protein, a putative prophage holin, respiratory nitrate reductase NarG, and three proteins of unknown function. Using quantitative real-time PCR comparing RNA isolated from in vitro cultured B. anthracis to RNA isolated from BALB/c mice infected with virulent Ames strain B. anthracis, we confirmed induced expression in vivo for a subset of B. anthracis genes identified by IVIAT, including L-alanine amidases BA3767, BA4073, and amiA (pXO2-42); the bacteriophage holin gene BA4074; and pagA (pXO1-110). The exogenous addition of two purified putative autolysins identified by IVIAT, N-acetylmuramoyl-L-alanine amidases BA0485 and BA2446, to vegetative B. anthracis cell suspensions induced a species-specific change in bacterial morphology and reduction in viable bacterial cells. Many of the proteins identified in our screen are predicted to affect peptidoglycan re-modeling, and our results support significant cell wall structural remodeling activity during B. anthracis infection. Identification of L-alanine amidases with B. anthracis specificity may suggest new potential therapeutic targets

Biogenesis and functions of bacterial S-layers.

The outer surface of many archaea and bacteria is coated with a proteinaceous surface layer (known as an S-layer), which is formed by the self-assembly of monomeric proteins into a regularly spaced, two-dimensional array. Bacteria possess dedicated pathways for the secretion and anchoring of the S-layer to the cell wall, and some Gram-positive species have large S-layer-associated gene families. S-layers have important roles in growth and survival, and their many functions include the maintenance of cell integrity, enzyme display and, in pathogens and commensals, interaction with the host and its immune system. In this Review, we discuss our current knowledge of S-layer and related proteins, including their structures, mechanisms of secretion and anchoring and their diverse functions

Consequences of TIPSS placement on the body composition of patients with cirrhosis and severe portal hypertension: a large retrospective CT-based surveillance.

Body composition may be modified after improvement of portal hypertension (PHT) by transjugular intrahepatic portosystemic shunt (TIPSS) insertion. To evaluate changes in body composition following TIPSS placement, their relationship with radiological TIPSS patency and function, and the predictive value of these parameters METHODS: We retrospectively included 179 patients with cirrhosis who underwent TIPSS placement in our centre for severe PHT from 2011 to 2017. CT scan-based surveillance was performed at baseline, 1-3 (M1-M3) and 6 months (M6). The median model for end-stage liver disease (MELD) score was 11.4 (8.8-15.1) and Child-Pugh score 8 (7-9). Only the MELD score (HR 1.14, 95% CI 1.08-1.20) and sarcopenia assessed by transversal right psoas muscle thickness at the umbilical level/height (TPMPT/height) (HR 0.86, 95% CI 0.79-0.96) were independently associated with 6-month mortality on multivariate analysis. After TIPSS insertion, TPMT/height increased from 19 mm/m (baseline) to 19.6 mm/m (M1-M3, P = 0.004) and 21.1 mm/m (M6, P < 0.0001). The improvement and its extent were dependent on the radiological patency and dysfunction of TIPSS. Subcutaneous fat surface (SCFS) increased from 183.4 to 193 cm <sup>2</sup> (P < 0.0001) and 229.8 cm <sup>2</sup> (P < 0.0001), respectively. We observed a decrease in visceral fat surface (VFS) between baseline and M1-M3 (163.5-140.5 cm <sup>2</sup> [P < 0.0001]), but not between M1-M3 and M6 (140.5-141.2 cm <sup>2</sup> [P = 0.9]). SCFS and VFS did not seem to be modified by radiological TIPSS patency and dysfunction. Sarcopenia is independently associated with 6-month outcome and improves after TIPSS placement, together with an inverse evolution of subcutaneous and visceral fat. TIPSS not only treats PHT but also improves body composition