A front-face 'SNi synthase' engineered from a retaining 'double-SN2' hydrolase.

SNi-like mechanisms, which involve front-face leaving group departure and nucleophile approach, have been observed experimentally and computationally in chemical and enzymatic substitution at α-glycosyl electrophiles. Since SNi-like, SN1 and SN2 substitution pathways can be energetically comparable, engineered switching could be feasible. Here, engineering of Sulfolobus solfataricus ß-glycosidase, which originally catalyzed double SN2 substitution, changed its mode to SNi-like. Destruction of the first SN2 nucleophile through E387Y mutation created a ß-stereoselective catalyst for glycoside synthesis from activated substrates, despite lacking a nucleophile. The pH profile, kinetic and mutational analyses, mechanism-based inactivators, X-ray structure and subsequent metadynamics simulations together suggest recruitment of substrates by π-sugar interaction and reveal a quantum mechanics-molecular mechanics (QM/MM) free-energy landscape for the substitution reaction that is similar to those of natural, SNi-like glycosyltransferases. This observation of a front-face mechanism in a ß-glycosyltransfer enzyme highlights that SNi-like pathways may be engineered in catalysts with suitable environments and suggests that 'ß-SNi' mechanisms may be feasible for natural glycosyltransfer enzymes.

Profiling and characterisation by liquid chromatography/multi-stage mass spectrometry of the chlorogenic acids in Gardeniae Fructus.

The chlorogenic acids of Gardeniae Fructus used traditionally as a Chinese herbal medicine (zhizi) have been investigated qualitatively by liquid chromatography/multi-stage mass spectrometry (LC/MS(4)). Twenty-nine chlorogenic acids were detected and twenty-five characterised to regioisomer level on the basis of their fragmentation, twenty-four for the first time from this source. Assignment to the level of individual regioisomers was possible for three caffeoylquinic acids, three dicaffeoylquinic acids, three sinapoylquinic acids, four caffeoyl-sinapoylquinic acids, two feruloyl-sinapoylquinic acids, one p-coumaroyl-sinapoylquinic acid, three (3-hydroxy, 3-methyl)glutaroylquinic acids, two (3-hydroxy, 3-methyl)glutaroyl-feruloylquinic acids, one (3-hydroxy, 3-methyl)glutaroyl-dicaffeoylquinic acid, and one (3-hydroxy, 3-methyl)glutaroyl-caffeoyl-feruloylquinic acid. Six (3-hydroxy, 3-methyl)glutaroyl-caffeoylquinic acids were detected and two were tentatively assigned as 3-caffeoyl-4-(3-hydroxy, 3-methyl)glutaroylquinic acid and 3-caffeoyl-5-(3-hydroxy, 3-methyl)glutaroylquinic acid. The (3-hydroxy, 3-methyl)glutaroyl residue modifies the mass spectral fragmentation behavior and elution sequence compared with the chlorogenic acids that contain only a cinnamic acid residue(s). Fourteen of these twenty-nine chlorogenic acids have not previously been reported from any source.

Patient and public involvement in the design of clinical trials: An overview of systematic reviews.

BACKGROUND: Funders encourage lay-volunteer inclusion in research. There are controversy and resistance, given concerns of role confusion, exploratory methods, and limited evidence about what value lay-volunteers bring to research. This overview explores these areas. METHODS: Eleven databases were searched without date or language restrictions for systematic reviews of public and patient involvement (PPI) in clinical trials design. This systematic overview of PPI included 27 reviews from which areas of good and bad practice were identified. Strengths, weaknesses, opportunities, and threats of PPI were explored through use of meta-narrative analysis. RESULTS: Inclusion criteria were met by 27 reviews ranging in quality from high (n = 7), medium (n = 14) to low (n = 6) reviews. Reviews were assessed using CERQUAL NICE, CASP for qualitative research and CASP for systematic reviews. Four reviews report risk of bias. Public involvement roles were primarily in agenda setting, steering committees, ethical review, protocol development, and piloting. Research summaries, follow-up, and dissemination contained PPI, with lesser involvement in data collection, analysis, or manuscript authoring. Trialists report difficulty in finding, retaining, and reimbursing volunteers. Respectful inclusion, role recognition, mutual flexibility, advance planning, and sound methods were reported as facilitating public involvement in research. Public involvement was reported to have increased the quantity and quality of patient relevant priorities and outcomes, enrollment, funding, design, implementation, and dissemination. Challenges identified include lack of clarity within common language, roles, and research boundaries, while logistical needs include extra time, training, and funding. Researchers report struggling to report involvement and avoid tokenism. CONCLUSIONS: Involving patients and the public in clinical trials design can be beneficial but requires resources, preparation, training, flexibility, and time. Issues to address include reporting deficits for risk of bias, study quality, and conflicts of interests. We need to address these tensions and improve dissemination strategies to increase PPI and health literacy.

Profiling the chlorogenic acids and other caffeic acid derivatives of herbal chrysanthemum by LC-MSn.

Four samples of herbal chrysanthemum have been profiled qualitatively by LC-MS5 to identify their component chlorogenic acids and partially characterize other caffeic acid derivatives. The chlorogenic acids were minor components, and the four samples varied markedly in profile. Three p-coumaroylquinic acids, three feruloylquinic acids, four caffeoylquinic acids, six dicaffeoylquinic acids, and two tricaffeoylquinic acids were detected, 13 for the first time from this source. Partial characterization of minor components suggested the presence of five caffeoyl-hexose esters and caffeic acid-4-beta-d-glucose that have not previously been reported from this source, and eight caffeoylquinic acid glycosides and 16 dicaffeoylquinic acid glycosides that have not previously been reported in nature. Succinic acid-containing chlorogenic acids and chlorogenic acids based on epi-quinic acid, previously reported in Chrysanthemum spp., were not detected in these samples.

Mind the gap in clinical trials: A participatory action analysis with citizen collaborators.

What are the strengths, gaps, expectations, and barriers to research engagement in clinical trials as communicated through social media? Clinical trials test treatments to provide reliable information for safety and effectiveness. Trials are building blocks in which what is learned in earlier research can be used to improve treatments, compare alternatives, and improve quality of life. For 20 years, the percentages of clinical trials volunteers have decreased whereas the costs of running clinical trials have multiplied. Participants enroll in trials to access latest treatments, to help others, and to advance science, but there is growing unrest. The priorities of those running the trials differ from those of the participants, and the roles for public research involvement lack clarity. Changes to bridge these gaps in the research culture are proposed through the use of participatory action research (PAR) in which stakeholders collaborate to improve research methodology, galvanize citizen participation, multiply health knowledge, problem-solve barriers to access, and explore the value of research volunteers as collaborators. PAR enabled the inclusion of citizens as full collaborators. Social media data were gathered for 120 days until saturation was reached. De-identified data were organized into a Strengths Weaknesses, Opportunities and Threats framework and coded into themes for analysis. After the analysis, the authors prioritized potential solutions for improving research engagement. Strengths and opportunities remained constant through trial phases, disease burdens, and interventions. Threats included alienation, litigation, disparity, and shaming. Poor management and barriers to inclusion were identified as weaknesses. Opportunities included improving resource management and information quality. Barriers were minimized when relationships between staff and participants were inclusive, respectful, tolerant, and open to change. Participants' communications ranged from fulfillment through trial involvement to disparities and rights violations. PAR provides a safe space without power imbalances in which researchers and citizen worked as equals rather than as researchers and objects of research.

Repeated oral administration modulates the pharmacokinetic behavior of the chemopreventive agent phenethyl isothiocyanate in rats.

The principal objective of this study was to evaluate whether repeated oral administration influences the pharmacokinetic behavior of the chemopreventive agent phenethyl isothiocyanate (PEITC) in rat. Animals were treated orally with 0.5, 1.0 and 5.0 mg/kg of the isothiocyanate for 4 days, and plasma levels at various times post-administration were determined by LC/MS after the first and last day. To determine absolute bioavailability, a group of animals was treated with a single (0.5 mg/kg) intravenous dose of PEITC. Following single oral dose administration, PEITC was rapidly absorbed, peak plasma concentrations being attained within the hour, and achieved an absolute bioavailability of 77%, but displayed dose-dependent pharmacokinetics, with bioavailability decreasing and clearance increasing moderately with dose; C(max) values did not rise proportionately to the dose and volume of distribution increased. At the higher doses of 1.0 and 5.0 mg/kg, repeated administration led to higher PEITC plasma C(max) concentrations and decreased plasma clearance of the isothiocyanate leading to enhanced bioavailability.