Discovery and Characterization of 2‐(Cyclopropanesulfonamido)‐N‐(2‐ethoxyphenyl)benzamide,ML382: a Potent and Selective Positive Allosteric Modulator of MrgX1

Previous studies have shown that the activation of mouse MrgC11, a G‐protein‐coupled receptor, by its peptide ligand BAM8‐22 can inhibit chronic pain. A large‐scale screen has been carried out to isolate small‐molecule allosteric agonists of MrgX1, the human homologue of MrgC11. The goal of this study is to improve the efficacy and potency of positive allosteric modulators (PAMs) with therapeutic implications in combating chronic pain. Herein we report an iterative parallel synthesis effort and a structure–activity relationship study of a series of arylsulfonamides which led to the discovery of the first PAM of MrgX1, ML382.     

Twenty-four-hour heart preservation using continuous cold perfusion and copper (II) complexes

Spinocerebellar ataxia 7 (SCA7) is a neurodegenerative disorder characterized by degeneration of the cerebellum, brainstem and retina. The gene responsible for SCA7, located on chromosome 3p, recently was cloned and shown to contain a CAG repeat in the coding region of the gene, that is expanded in SCA7 patients of French origin. We examined the SCA7 repeat region in four Swedish SCA7 families as well as in 57 healthy controls. All Swedish SCA7 patients exhibited expanded CAG repeats with a strong negative correlation between repeat size and age of onset. The repeat length in SCA7 patients ranged from 40 to >200 repeats. The largest expansion was observed in a juvenile case with an age of onset of 3 months, and represents the longest polyglutamine stretch ever reported. In patients with 59 repeats or more, visual impairment was the most common initial symptom observed, while ataxia predominates in patients with <59 repeats. Two of the Swedish SCA7 families analysed in this study were shown to be related genealogically. The other two SCA7 families could not be traced back to a common ancestor. All four families shared the same allele on the disease chromosome at a locus closely linked to SCA7, suggesting the possibility of a founder effect in the Swedish population.     

The diurnal distribution of sleep propensity: experimental data about the interaction of the propensities for slow-wave sleep and REM sleep

The aim of the present study was to assess the diurnal variation of sleep propensity by evaluating the temporal distribution of sleep onset latency (SOL) and REM- and slow-wave sleep (SWS) parameters in systematically scheduled daytime naps for 12 young males. To reduce the effect of prior SWS on subsequent REM sleep, a double-nap technique was used, i.e. two adjacent naps A and B, which were separated by a 10-min break. Nap duration was adjusted in such a way that nap A allowed 30 min of sleep and nap B one complete NREM-REM cycle. EEG slow wave activity (SWA, power density from 0.5-4 Hz) was estimated from nap A and REM sleep parameters from nap B. The time span between 08.00 hours and 24.00 hours was covered by nine double-naps at 2 h intervals. The order of the nap sessions was systematically varied within and across subjects. For each subject, the time between successive double-nap recordings was at least three days. SOL was shortest in the time interval 12.00 hours to 16.00 hours and significantly longer between 20.00 hours and 24.00 hours. REM sleep duration and the percentage of sleep onset REM episodes decreased continuously from 08.00 hours to the interval 18.00-20.00 hours and increased thereafter, with a time course inversely related to the one of body temperature, which was also measured continuously. SWA showed a steady, threefold increase from 08.00 hours to 24.00 hours. The study offers new data on the diurnal variation of sleep propensity which seems to be a composite function of the drives for SWS and REM sleep.     

Lack of nitric oxide contributes to vasospasm during ischemia/reperfusion injury

Vasospasm can be a complication after free tissue transfer and replant operations. Recent studies suggest that vasospasm may be due to endothelium dysfunction, resulting in impairment of nitric oxide production. The present experiment was designed to investigate acute responses of the microcirculation of skeletal muscle to local interarterial infusion of sodium nitroprusside (a direct donor of nitric oxide and thus an endothelium-independent vasodilator) or acetylcholine chloride (which stimulates endothelium release of endogenous nitric oxide) during reperfusion after 4 hours of warm ischemia. Male Sprague-Dawley rats, each weighing 100 to 120 gm, were anesthetized with sodium pentobarbitone and were surgically prepared with vascular isolated and denervated cremaster muscles that were subjected to 4 hours warm ischemia and 2 hours of reperfusion. Sodium nitroprusside (10(-3) M), acetylcholine chloride (10(-4) M), or normal saline (eight rats for each group) were administered by local infusion (0.1 ml/hour) through the femoral artery into the natural blood flow of the cremaster. The arterial tree in the cremaster was observed and arteriole diameters (A1-A4) were measured using intravital microscopy. The number of arteriole branches having temporary stoppage of flow were counted in each cremaster. The results from this study show that local infusion of sodium nitroprusside, but not acetylcholine chloride, prevents ischemia/reperfusion vasoconstriction in A3 and A4 arterioles and thus improves microvascular blood flow. Generalized vasoconstriction caused by topically applied norepinephrine (10(-6) M) to sham ischemia cremasters could be completely reversed by the local infusion of 10(-4) M acetylcholine chloride. These results indicate that vasospasm after ischemia/reperfusion may be related to temporary endothelial cell dysfunction, resulting in the inability to produce sufficient nitric oxide during early reperfusion. Vascular smooth muscle, however, is responsive to locally administered sodium nitroprusside infusion (which is thought to provide exogenous nitric oxide).     

Evolutionary journey and characterisation of a novel pan-gene associated with beer strains of Saccharomyces cerevisiae

The sequencing of over a thousand Saccharomyces cerevisiae genomes revealed a complex pangenome. Over one third of the discovered genes are not present in the S. cerevisiae core genome but instead are often restricted to a subset of yeast isolates and thus may be important for adaptation to specific environmental niches. We refer to these genes as “pan-genes,” being part of the pangenome but not the core genome. Here, we describe the evolutionary journey and characterisation of a novel pan-gene, originally named hypothetical (HYPO) open-reading frame. Phylogenetic analysis reveals that HYPO has been predominantly retained in S. cerevisiae strains associated with brewing but has been repeatedly lost in most other fungal species during evolution. There is also evidence that HYPO was horizontally transferred at least once, from S. cerevisiae to Saccharomyces paradoxus. The phylogenetic analysis of HYPO exemplifies the complexity and intricacy of evolutionary trajectories of genes within the S. cerevisiae pangenome. To examine possible functions for Hypo, we overexpressed a HYPO-GFP fusion protein in both S. cerevisiae and Saccharomyces pastorianus. The protein localised to the plasma membrane where it accumulated initially in distinct foci. Time-lapse fluorescent imaging revealed that when cells are grown in wort, Hypo-gfp fluorescence spreads throughout the membrane during cell growth. The overexpression of Hypo-gfp in S. cerevisiae or S. pastorianus strains did not significantly alter cell growth in medium-containing glucose, maltose, maltotriose, or wort at different concentrations.