A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins.

Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the timescale of ps-μs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of μs-ms, corresponding to large-scale protein motions, is inaccessible to those methods.

Noninferior Immunogenicity and Consistent Safety of Respiratory Syncytial Virus Prefusion F Protein Vaccine in Adults 50-59 Years Compared to ≥60 Years of Age.

Background: The adjuvanted respiratory syncytial virus (RSV) prefusion F protein-based vaccine (RSVPreF3 OA) is approved in adults aged ≥60 years. We evaluated RSVPreF3 OA immunogenicity and safety in adults aged 50-59 years without or with increased risk for RSV disease due to specific chronic medical conditions.

Methods: This observer-blind, phase 3, noninferiority trial included adults aged 50-59 years, stratified into 2 subcohorts: those with and those without predefined, stable, chronic medical conditions leading to an increased risk for RSV disease.

A pressure-jump EPR system to monitor millisecond conformational exchange rates of spin-labeled proteins.

Site-directed spin labeling electron paramagnetic resonance (SDSL-EPR) using nitroxide spin labels is a well-established technology for mapping site-specific secondary and tertiary structure and for monitoring conformational changes in proteins of any degree of complexity, including membrane proteins, with high sensitivity. SDSL-EPR also provides information on protein dynamics in the time scale of ps-µs using continuous wave lineshape analysis and spin lattice relaxation time methods. However, the functionally important time domain of µs-ms, corresponding to large-scale protein motions, is inaccessible to those methods.

Creating a Defined Chirality in Amino Acids and Cyclic Dipeptides by Photochemical Deracemization.

2,5-Diketopiperazines are cyclic dipeptides displaying a wide range of applications. Their enantioselective preparation has now been found possible from the respective racemates by a photochemical deracemization (53 examples, 74 % to quantitative yield, 71-99 % ee). A chiral benzophenone catalyst in concert with irradiation at λ=366 nm enables to establish the configuration at the stereogenic carbon atom C6 at will.

Catalytic Photochemical Deracemization via Short-Lived Intermediates.

Upon irradiation in the presence of a suitable chiral catalyst, racemic compound mixtures can be converted into enantiomerically pure compounds with the same constitution. The process is called photochemical deracemization and involves the formation of short-lived intermediates. By opening different reaction channels for the forward reaction to the intermediate and for the re-constitution of the chiral molecule, the entropically disfavored process becomes feasible.

Photochemical Deracemization of 3-Substituted Oxindoles.

Racemic 3-substituted oxindoles were successfully converted into enantiomerically pure or enriched material (up to 99 % ee) upon irradiation at λ=366 nm in the presence of a chiral benzophenone catalyst (10 mol %). The photochemical deracemization process allows predictable editing of the stereogenic center at carbon atom C3. Light energy compensates for the associated loss of entropy and enables the decoupling of potentially reversible reactions, i.

Multifaceted View on the Mechanism of a Photochemical Deracemization Reaction.

Upon irradiation in the presence of a chiral benzophenone catalyst (5 mol %), a racemic mixture of a given chiral imidazolidine-2,4-dione (hydantoin) can be converted almost quantitatively into the same compound with high enantiomeric excess (80-99% ). The mechanism of this photochemical deracemization reaction was elucidated by a suite of mechanistic experiments. It was corroborated by nuclear magnetic resonance titration that the catalyst binds the two enantiomers by two-point hydrogen bonding.

Visible Light-Mediated Dearomative Hydrogen Atom Abstraction/ Cyclization Cascade of Indoles.

The photochemical synthesis of yet unknown 2-oxospiro[azetidine-3,3'-indolines] (17 examples, 80-95 % yield), 2,4-dioxospiro[azetidine-3,3'-indolines] (eight examples, 87-97 % yield), and 1-oxo-1,3-dihydrospiro[indene-2,3'-indolines] (17 examples, 85-97 % yield) is described. Starting from readily accessible 3-substituted indoles, a dearomatization of the indole core was accomplished upon irradiation at λ=420 nm in the presence of thioxanthen-9-one (10 mol%) as the sensitizer. Based on mechanistic evidence (triplet energy determination, deuteration experiments, by-product analysis) it is proposed that the reaction proceeds by energy transfer via a 1,4- or 1,5-diradical intermediate.

Photochemical Deracemization at sp-Hybridized Carbon Centers via a Reversible Hydrogen Atom Transfer.

A photochemical deracemization of 5-substituted 3-phenylimidazolidine-2,4-diones (hydantoins) is reported (27 examples, 69%-quant., 80-99% ). The reaction is catalyzed by a chiral diarylketone which displays a two-point hydrogen bonding site.

Photochemical Deracemization of Primary Allene Amides by Triplet Energy Transfer: A Combined Synthetic and Theoretical Study.

The photochemical deracemization of 2,4-disubstituted 2,3-butadienamides (allene amides) was investigated both experimentally and theoretically. The reaction was catalyzed by a thioxanthone which is covalently linked to a chiral 1,5,7-trimethyl-3-azabicyclo[3.3.

Enantioselective Photochemical Reactions Enabled by Triplet Energy Transfer.

For molecules with a singlet ground state, the population of triplet states is mainly possible (a) by direct excitation and subsequent intersystem crossing or (b) by energy transfer from an appropriate sensitizer. The latter scenario enables a catalytic photochemical reaction in which the sensitizer adopts the role of a catalyst undergoing several cycles of photon absorption and subsequent energy transfer to the substrate. If the product molecule of a triplet-sensitized process is chiral, this process can proceed enantioselectively upon judicious choice of a chiral triplet sensitizer.

Enantioselective, Visible Light Mediated Aza Paternò-Büchi Reactions of Quinoxalinones.

3-Substituted quinoxalin-2(1H)-ones and various aryl-substituted or tethered olefins underwent an enantioselective, inter- or intramolecular aza Paternò-Büchi reaction upon irradiation at λ=420 nm in the presence of a chiral sensitizer (10 mol %). For the intermolecular reaction with 1-arylethenes as olefin components, the scope of the reaction was studied (14 examples, 50-99 % yield, 86-98 % ee). The absolute and relative configuration of the products were elucidated by single-crystal X-ray crystallography.

Closed fumarase C active-site structures reveal SS Loop residue contribution in catalysis.

Fumarase C (FumC) catalyzes the reversible conversion of fumarate to S-malate. Previous structural investigations within the superfamily have reported a dynamic structural segment, termed the SS Loop. To date, active-site asymmetry has raised the question of how SS Loop placement affects participation of key residues during the reaction.

Endoglucanases Mediate the Rate of Pierce's Disease Development in in a Cultivar-Dependent Manner.

is a gram-negative bacterium that causes Pierce's disease (PD) in grapevine. is xylem-limited and interfaces primarily with pit membranes (PMs) that separate xylem vessels from one another and from adjacent xylem parenchyma cells. PMs are composed of both pectic and cellulosic substrates, and dissolution of PMs is facilitated by cell wall-degrading enzymes.

Nalmefene, Given as Needed, in the Routine Treatment of Patients with Alcohol Dependence: An Interventional, Open-Label Study in Primary Care.

Aims: This 12-week, open-label, primary care study (NCT02195817) evaluated the efficacy and safety of nalmefene, taken as needed, to reduce alcohol consumption in adults with a diagnosis of alcohol dependence and drinking at least at high drinking risk levels (DRL, > 60 g/day for men, > 40 g/day for women).

Methods: Following the Screening Visit, patients recorded their daily alcohol consumption for 2 weeks. Patients were then categorised by their self-reported drinking levels; those who maintained at least a high DRL in the 2-week period were included in Cohort-A, and those who reduced their alcohol consumption below high DRL were included in Cohort-B.

A randomized, placebo-controlled study of oxcarbazepine in painful diabetic neuropathy.

Objectives: To evaluate the efficacy and safety of oxcarbazepine (1200 mg/day) in patients with painful diabetic neuropathy in a multicentre, double-blind, placebo-controlled, 16-week study.

Methods: A total of 141 patients were randomized to oxcarbazepine (1200 mg/day) (n = 71) or placebo (n = 70). The primary efficacy variable was the change in mean visual analogue scale (VAS) score from baseline to the last week the patient participated in the study.

Use of the cardiopulmonary flow index to evaluate cardiac function in thoroughbred horses.

The ratio of the cardiopulmonary blood volume to stroke volume is called the cardiopulmonary flow index (CPFI). The CPFI can be determined indirectly from the simultaneous recording of a radiocardiogram and an electrocardiogram. The CPFI and cardiac output were measured simultaneously in horses (n = 10) that were diagnosed as having cardiac disease.

Physiological and blood biochemical responses to submaximal treadmill exercise in Canaan dogs before, during and after training.

Physiological haematological and blood biochemical parameters were studied in Canaan dogs (n = 8) as possible indices of fitness. These parameters were then used to distinguish between fit and unfit dogs and to monitor the changes in these parameters during training and detraining periods. Fitness was defined as the ability to run for one hour on a motorised treadmill (speed 8.

Blood biochemical parameters and meat pH of feedlot cattle slaughtered on arrival or after overnight rest at an abattoir.

The effect of different pre-slaughter rest periods at the abattoir before slaughter on the blood biochemical parameters and meat pH of a number of cattle were studied on 2 occasions, once in summer and once in winter. In the first trial, 42 out of a consignment of 50 and in the second trial, 45 out of a consignment of 54 feedlot-finished oxen were randomly selected and divided into 3 groups each. One group was slaughtered on arrival at the abattoir, a second group 3 h after arrival and the third group was rested in the lairage prior to slaughter the following day.

Plasma progesterone levels in progesterone treated cows.

A technique for the radioimmunoassay of progesterone in plasma is described. In one trial the oestrous cycles of four cycling cows and in another trial of one non-cycling cow and two cycling heifers were synchronized by the administration of progesterone. Each female received either 50 mg or 0,1 mg/kg of progesterone intramuscularly on alternate days in two courses of four and six injections respectively.

[Activity of serum gonadotropins in pregnant zebras and mares].

Blood was collected from 28 zebra mare (Equus burchellia antiquorum) immediately after being shot in the Kruger National Park. The serum was separated within two hours after collection and then stored at -15 degrees C for later assay. Of these, thirteen selected samples were tested for gonadotrophic activity.