A quasi-elastic light scattering study of smooth muscle myosin in the presence of ATP

We have investigated the hydrodynamic properties of turkey gizzard smooth muscle myosin in solution using quasi-elastic light scattering (QELS). The effects of ionic strength (0.05–0.5 M KCl) and light chain phosphorylation on the conformational transition of myosin were examined in the presence of ATP at 20 degrees C. Cumulant analysis and light scattering models were used to describe the myosin system in solution. A nonlinear least squares fitting procedure was used to determine the model that best fits the data. The conformational transition of the myosin monomer from a folded form to an extended form was clearly demonstrated in a salt concentration range of 0.15–0.3 M KCl. Light chain phosphorylation regulates the transition and promotes unfolding of the myosin. These results agree with the findings obtained using sedimentation velocity and electron microscopy (Onishi and Wakabayashi, 1982; Trybus et al., 1982; Trybus and Lowey, 1984). In addition, we present evidence for polymeric myosin coexisting with the two monomeric myosin species over a salt concentration range from 0.05 to 0.5 M KCl. The size of the polymeric myosin varied with salt concentration. This observation supports the hypothesis that, in solution, a dynamic equilibrium exists between the two conformations of myosin monomer and filaments

Additional file 1: of Managing uncertainty - a qualitative study of surgeons’ decision-making for one-stage and two-stage revision surgery for prosthetic hip joint infection

Infection after total joint replacement: Surgeon Topic Guide. Interview topic guide used by the researcher during interviews with surgeons. (DOCX 21 kb

Concatenation and species tree methods exhibit statistically indistinguishable accuracy under a range of simulated conditions

<p>50speciesTrees: Fifty species trees of eight taxa. Trees are in newick format but .nex extension needed for simulation script to work</p> <p>simulation.pl : Perl script to simulate 540 gene trees with corresponding 1000bp sequences for all 50 species trees at both tree depths and with varying number of individuals per species. Requires seqgen and ms in same directory to run</p> <p>mbconcat2.py : Python script to concatenate by three, nine and 27 and run MrBayes. Nexus files for each species tree must be in own directory. Input and output directories need to be provided</p

Toward Understanding of Bio-Oil Aging: Accelerated Aging of Bio-Oil Fractions

Pyrolysis bio-oil from biomass is a promising intermediate for producing transportation fuels and platform chemicals. However, its instability, often called aging, has been identified as a critical hurdle that prevents bio-oil from being commercialized. The objective of this research is to explore the bio-oil aging mechanism by an accelerated aging test of fractionated bio-oil produced from loblolly pine. When water soluble (WS), ether insoluble (EIS), and pyrolytic lignin (PL) fractions were aged separately, the increased molecular weight (Mw) was observed with increasing aging temperature and the presence of acids. WS and EIS fractions had high Mw brown solids formed after aging. Adjusting the pH of WS and EIS fractions from 2.5 to 7.0 significantly reduced the tendency of a Mw increase. Similar Mw rise was also observed on a PL fraction with an elevated temperature and acid addition. Formaldehyde was found to react with the PL fraction in the presence of any acid catalysts tested, i.e., 8-fold Mw increase in acetic acid environment, while other bio-oil aldehydes did not significantly promote lignin condensation. To better understand bio-oil stability, a potential bio-oil aging pattern was proposed, suggesting that bio-oil can be aged within or between its fractions

Thermal and Storage Stability of Bio-Oil from Pyrolysis of Torrefied Wood

The objective of this paper is to investigate the biomass torrefaction effect on bio-oil stability by comparing the physicochemical and compositional properties of aged bio-oils. Two aging methods, accelerated aging (held at 80 °C for 24 h) and long-term natural aging (12-month storage at 25 °C), were employed to produce aged bio-oils for such comparison. The results indicate that bio-oils made from heat-treated wood had similar aging behavior in terms of increase of water content, acid content, molecular weight, and viscosity. The increase rate, however, was found to be different and dependent on the aging method. The accelerated method found parallel water and total acidity number (TAN) increments between raw and torrefaction bio-oils, while the natural aging method found torrefaction bio-oils, especially those made from heavily treated wood, had much slower water and acid accumulation than that of raw bio-oil. As a negative effect, both methods identified the viscosity of torrefaction bio-oils increased more significantly than that of raw bio-oil, while their molecular weights were unexpectedly lower. The correlation study showed that bio-oil viscosity is more tied to the content of bio-oil–water insoluble fraction rather than its average molecular weight. In addition, the characterization of aged bio-oils using NMR, GC/MS, and solvent fractionation indicated that torrefaction bio-oils had less compositional alternation after accelerated aging than the raw bio-oil. Also, they were more stable during the first 6 months of storage at room temperature. During the long-term storage, the raw bio-oil completely phase-separated after 6 months. However, two distinct torrefaction bio-oils (LP-280T and LP-330T) had enhanced phase stability, as a stable uniform oil phase without gum formation can be maintained during the entire 12-month storage

Additional file 2: of Development of a complex intervention for people with chronic pain after knee replacement: the STAR care pathway

Overview of STAR assessment clinic appointment, telephone follow-up and recommended treatment referral pathways. (DOCX 18 kb

<i>Helicobacter pylori</i>, HIV and Gastric Hypochlorhydria in the Malawian Population

<div><p>Background</p><p>HIV and <i>Helicobacter pylori</i> are common chronic infections in sub-Saharan Africa. Both conditions can predispose to gastric hypochlorhydria that may be a risk factor for enteric infections and reduced drug absorption. We have investigated to what extent HIV and <i>H</i>. <i>pylori</i> infections are associated with hypochlorhydria in a Malawian cohort of patients undergoing endoscopy.</p><p>Methods</p><p>104 sequential symptomatic adults referred for gastroscopy at Queen Elizabeth Central Hospital, Blantyre, Malawi, had blood taken for rapid HIV testing and fasting serum gastrin analysis. Gastric fluid was aspirated for pH testing, and gastric biopsies were taken.</p><p>Results</p><p>After 9/104 HIV-infected patients who were already established on anti-retroviral therapy were excluded, 17/95 (25.0%) were seropositive for untreated HIV, and 68/95 (71.6%) patients were <i>H</i>. <i>pylori</i> positive by histology. Hypochlorhydria (fasting gastric pH>4.0) was present in 55.8% (53/95) of patients. <i>H</i>. <i>pylori</i> infection was significantly associated with hypochlorhydria (OR 2.91, [1.02-7.75], p=0.046). While single infection with HIV was not significantly independently associated with hypochlorhydria. <i>H</i>. <i>pylori</i> and HIV co-infection was more strongly associated with hypochlorhydria (OR 6.25, [1.33-29.43], p=0.020) than either infection alone, suggesting an additive effect of co-infection. HIV infection was associated with higher serum gastrin levels (91.3pM vs. 53.1pM, p=0.040), while <i>H</i>. <i>pylori</i> infection was not (63.1pM vs. 55.1pM, p=0.610). Irrespective of <i>H</i>. <i>pylori</i> and HIV status, most patients (>90%) exhibited pangastritis. Only three patients had histological evidence of gastric atrophy, of which only one was HIV-infected.</p><p>Conclusion</p><p><i>H</i>. <i>pylori</i> infection was associated with fasting hypochlorhydria, while HIV was not independently associated. HIV and <i>H</i>. <i>pylori</i> co-infection, however, was more strongly associated with hypochlorhydria than <i>H</i>. <i>pylori</i> infection alone. The mechanism of this apparent additive effect between HIV and <i>H</i>. <i>pylori</i> remains unclear, but appears to be related to chronic pangastritis rather than gastric atrophy, and associated with hypergastrinaemia in HIV-infected individuals.</p></div

The scatterplot displays the absolute pH values for the four groups in relation to <i>H</i>.<i>pylori</i> and HIV infection status.

<p>The scatterplot displays the absolute pH values for the four groups in relation to <i>H</i>.<i>pylori</i> and HIV infection status.</p

Univariate and binary logistic regression by factors potentially associated with hypochlorhydria.

<p>Univariate and binary logistic regression by factors potentially associated with hypochlorhydria.</p

The scatterplot displays the serum gastrin (pM) levels for the four groups in relation to <i>H</i>.<i>pylori</i> and HIV infection status.

<p>The scatterplot displays the serum gastrin (pM) levels for the four groups in relation to <i>H</i>.<i>pylori</i> and HIV infection status.</p