α8β1 integrin regulates nutrient absorption through an Mfge8-PTEN dependent mechanism.

Coordinated gastrointestinal smooth muscle contraction is critical for proper nutrient absorption and is altered in a number of medical disorders. In this work, we demonstrate a critical role for the RGD-binding integrin α8β1 in promoting nutrient absorption through regulation of gastrointestinal motility. Smooth muscle-specific deletion and antibody blockade of α8 in mice result in enhanced gastric antral smooth muscle contraction, more rapid gastric emptying, and more rapid transit of food through the small intestine leading to malabsorption of dietary fats and carbohydrates as well as protection from weight gain in a diet-induced model of obesity. Mechanistically, ligation of α8β1 by the milk protein Mfge8 reduces antral smooth muscle contractile force by preventing RhoA activation through a PTEN-dependent mechanism. Collectively, our results identify a role for α8β1 in regulating gastrointestinal motility and identify α8 as a potential target for disorders characterized by hypo- or hyper-motility

The solution structure of the N-terminal domain of hepatocyte growth factor reveals a potential heparin-binding site

AbstractBackground: Hepatocyte growth factor (HGF) is a multipotent growth factor that transduces a wide range of biological signals, including mitogenesis, motogenesis, and morphogenesis. The N-terminal (N) domain of HGF, containing a hairpin-loop region, is important for receptor binding and the potent biological activities of HGF. The N domain is also the primary binding site for heparin or heparan sulfate, which enhances receptor/ligand oligomerization and modulates receptor-dependent mitogenesis. The rational design of artificial modulators of HGF signaling requires a detailed understanding of the structures of HGF and its receptor, as well as the role of heparin proteoglycan; this study represents the first step towards that goal.Results: We report here a high-resolution solution structure of the N domain of HGF. This first structure of HGF reveals a novel folding topology with a distinct pattern of charge distribution and indicates a possible heparin-binding site.Conclusions: The hairpin-loop region of the N domain plays a major role in stabilizing the structure and contributes to a putative heparin-binding site, which explains why it is required for biological functions. These results suggest several basic and/or polar residues that may be important for use in further mutational studies of heparin binding

Structure–Activity Relationship Studies of Functionally Selective Kappa Opioid Receptor Agonists that Modulate ERK 1/2 Phosphorylation While Preserving G Protein Over βArrestin2 Signaling Bias

Kappa opioid receptor (KOR) modulation is a promising target for drug discovery efforts due to KOR involvement in pain, depression, and addiction behaviors. We recently reported a new class of triazole KOR agonists that displays significant bias toward G protein signaling over βarrestin2 recruitment; interestingly, these compounds also induce less activation of ERK1/2 map kinases than the balanced agonist, U69,593. We have identified structure–activity relationships around the triazole scaffold that allows for decreasing the bias for G protein signaling over ERK1/2 activation while maintaining the bias for G protein signaling over βarrestin2 recruitment. The development of novel compounds, with different downstream signaling outcomes, independent of G protein/βarrestin2 bias, provides a more diverse pharmacological toolset for use in defining complex KOR signaling and elucidating the significance of KOR-mediated signaling

The Initial Step in Human Immunodeficiency Virus Type 1 GagProPol Processing Can Be Regulated by Reversible Oxidation

BACKGROUND: Maturation of human immunodeficiency virus type 1 (HIV-1) occurs upon activation of HIV-1 protease embedded within GagProPol precursors and cleavage of Gag and GagProPol polyproteins. Although reversible oxidation can regulate mature protease activity as well as retrovirus maturation, it is possible that the effects of oxidation on viral maturation are mediated in whole, or part, through effects on the initial intramolecular cleavage event of GagProPol. In order assess the effect of reversible oxidation on this event, we developed a system to isolate the first step in protease activation involving GagProPol. METHODOLOGY/PRINCIPAL FINDINGS: To determine if oxidation influences this step, we created a GagProPol plasmid construct (pGPfs-1C) that encoded mutations at all cleavage sites except p2/NC, the initial cleavage site in GagProPol. pGPfs-1C was used in an in vitro translation assay to observe the behavior of this initial step without interference from subsequent processing events. Diamide, a sulfhydral oxidizing agent, inhibited processing at p2/NC by >60% for pGPfs-1C and was readily reversed with the reductant, dithiothreitol. The ability to regulate processing by reversible oxidation was lost when the cysteines of the embedded protease were mutated to alanine. Unlike mature protease, which requires only oxidation of cys95 for inhibition, both cysteines of the embedded protease contributed to this inhibition. CONCLUSIONS/SIGNIFICANCE: We developed a system that can be used to study the first step in the cascade of HIV-1 GagProPol processing and show that reversible oxidation of cysteines of HIV-1 protease embedded in GagProPol can block this initial GagProPol autoprocessing. This type of regulation may be broadly applied to the majority of retroviruses

Identification and Dynamics of a Heparin-Binding Site in Hepatocyte Growth Factor †

Hepatocyte growth factor (HGF) is a heparin-binding, multipotent growth factor that transduces a wide range of biological signals, including mitogenesis, motogenesis, and morphogenesis. Heparin or closely related heparan sulfate has profound effects on HGF signaling. A heparin-binding site in the N-terminal (N) domain of HGF was proposed on the basis of the clustering of surface positive charges [Zhou, H., Mazzulla, M. J., Kaufman, J. D., Stahl, S. J., Wingfield, P. T., Rubin, J. S., Bottaro, D. P., and Byrd, R. A. (1998) Structure 6, 109-116]. In the present study, we confirmed this binding site in a heparin titration experiment monitored by nuclear magnetic resonance spectroscopy, and we estimated the apparent dissociation constant (K(d)) of the heparin-protein complex by NMR and fluorescence techniques. The primary heparin-binding site is composed of Lys60, Lys62, and Arg73, with additional contributions from the adjacent Arg76, Lys78, and N-terminal basic residues. The K(d) of binding is in the micromolar range. A heparin disaccharide analogue, sucrose octasulfate, binds with similar affinity to the N domain and to a naturally occurring HGF isoform, NK1, at nearly the same region as in heparin binding. (15)N relaxation data indicate structural flexibility on a microsecond-to-millisecond time scale around the primary binding site in the N domain. This flexibility appears to be dramatically reduced by ligand binding. On the basis of the NK1 crystal structure, we propose a model in which heparin binds to the two primary binding sites and the N-terminal regions of the N domains and stabilizes an NK1 dimer

Short-term CO\u3csub\u3e2\u3c/sub\u3e exposure and temperature rise effects on metazoan meiofauna and free-living nematodes in sandy and muddy sediments: Results from a flume experiment

© 2017 Elsevier B.V. Global concern over increasing CO2 emissions, and the resultant CO2 driven temperature rises and changes in seawater chemistry, necessitates the advancement of understanding into how these changes will affect marine life now and in the future. Here we report on an experimental investigation into the effects of increased CO2 concentration and elevated temperature on sedimentary meiofaunal communities. Cohesive (muddy) and non-cohesive (sandy) sediments were collected from the Eden Estuary in St. Andrews, Scotland, UK, placed within a flume setup and exposed to 2 levels of CO2 concentration (380 and 750 ppmv, current at the time of the experiment, and predicted CO2 concentration by 2100, respectively) and 2 temperature levels (12 °C and 16 °C, current in-situ and predicted temperature by 2100, respectively). We investigated the metazoan meiofauna and nematode communities before and after 28 days of exposure under these experimental conditions. The most determinative factor for abundance, diversity and community structure of meiofauna and nematodes was sediment type: on all levels, communities were significantly different between sand and mud sediments which agrees with what is generally known about the influence of sediment structure on meiofaunal organisms. Few CO2 and temperature effects were observed, suggesting that meiofauna and nematodes are generally much less responsive than, for instance, microbial communities and macrofauna to these environmental changes in estuarine environments, where organisms are naturally exposed to a fluctuating environment. This was corroborated by the observed effects related to the different seasons in which the samples were taken from the field to run the experiment. After 28 days, meiofauna and nematode communities in muddy sediments showed a greater response to increased CO2 concentration and temperature rise than in sandy sediments. However, further study is needed to investigate the underlying mechanisms and meiofauna species-specific resilience and responses to ocean acidification and warming, and their interactions with other biota, to understand what such changes may mean for meiofauna communities and the ecosystem processes and functions they contribute to

Randomised feasibility trial of the helping families programme-modified: an intensive parenting intervention for parents affected by severe personality difficulties.

BACKGROUND: Specialist parenting intervention could improve coexistent parenting and child mental health difficulties of parents affected by severe personality difficulties. OBJECTIVE: Conduct a feasibility trial of Helping Families Programme-Modified (HFP-M), a specialist parenting intervention. DESIGN: Pragmatic, mixed-methods trial, 1:1 random allocation, assessing feasibility, intervention acceptability and outcome estimates. SETTINGS: Two National Health Service health trusts and local authority children's social care. PARTICIPANTS: Parents: (i) primary caregiver, (ii) 18 to 65 years, (iii) severe personality difficulties, (iv) proficient English and (v) capacity for consent. Child: (i) 3 to 11 years, (ii) living with index parent and (iii) significant emotional/behavioural difficulties. INTERVENTION: HFP-M: 16-session home-based intervention using parenting and therapeutic engagement strategies. Usual care: standard care augmented by single psychoeducational parenting session. OUTCOMES: Primary feasibility outcome: participant retention rate. SECONDARY OUTCOMES: (i) rates of recruitment, eligibility and data completion, and (ii) rates of intervention acceptance, completion and alliance (Working Alliance Inventory-Short Revised). Primary clinical outcome: child behaviour (Eyberg Child Behaviour Inventory). SECONDARY OUTCOMES: child mental health (Concerns About My Child, Child Behaviour Checklist-Internalising Scale), parenting (Arnold-O'Leary Parenting Scale, Kansas Parental Satisfaction Scale) and parent mental health (Symptom-Checklist-27). Quantitative data were collected blind to allocation. RESULTS: Findings broadly supported non-diagnostic selection criterion. Of 48 participants recruited, 32 completed post-intervention measures at mean 42 weeks later. Participant retention exceeded a priori rate (HFP-M=18; Usual care=14; 66.7%, 95% CI 51.6% to 79.6%). HFP-M was acceptable, with delivery longer than planned. Usual care had lower alliance rating. Child and parenting outcome effects detected across trial arms with potential HFP-M advantage (effect size range: 0.0 to 1.3). CONCLUSION: HFP-M is an acceptable and potentially effective specialist parenting intervention. A definitive trial is feasible, subject to consideration of recruitment and retention methods, intervention efficiency and comparator condition. Caution is required in interpretation of results due to reduced sample size. No serious adverse events reported. TRIAL REGISTRATION NUMBER: ISRCTN14573230

The attrition rate of licensed chiropractors in California: an exploratory ecological investigation of time-trend data

<p>Abstract</p> <p>Background</p> <p>The authors hypothesized the attrition rate of licensed chiropractors in California has gradually increased over the past several decades. "Attrition" as determined for this study is defined as a loss of legal authority to practice chiropractic for any reason during the first 10 years after the license was issued. The percentage of license attrition after 10 years was determined for each group of graduates licensed in California each year between 1970 and 1998. The cost of tuition, the increase in the supply of licensed chiropractors and the ratio of licensed chiropractors to California residents were examined as possible influences on the rate of license attrition.</p> <p>Methods</p> <p>The attrition rate was determined by a retrospective analysis of license status data obtained from the California Department of Consumer Affairs. Other variables were determined from US Bureau of Census data, survey data from the American Chiropractic Association and catalogs from a US chiropractic college.</p> <p>Results</p> <p>The 10-year attrition rate rose from 10% for those graduates licensed in 1970 to a peak of 27.8% in 1991. The 10-year attrition rate has since remained between 20-25% for the doctors licensed between 1992-1998.</p> <p>Conclusions</p> <p>Available evidence supports the hypothesis that the attrition rate for licensed chiropractors in the first 10 years of practice has risen in the past several decades.</p