Blocked dihydropteridines as nitric oxide synthase activators

It has been shown that 6-acetyl-7,7-dimethyl-5,6,7,8-tetrahydropteridin-4(3H)-one can act as a competent cofactor for the production of nitric oxide by neuronal nitric oxide synthase (nNOS). More information was sought on the structural features that could contribute to strong binding within the enzyme whilst maintaining a fast electron transfer rate. This study was concerned with expansion at the C2-position of the pteridine scaffold. The evidence suggests that expansion at the C2-position had a deleterious effect with respect to Km and as a consequence electron transfer rate. Unexpectedly, several lines of evidence suggested that a methyl substituent on nitrogen at C2 reduced the electron density in the pyrimidine and dihydropterin rings

The Extracellular Heat Shock Protein 72 Response to a 7-day Desert-based Ultra-marathon

Extracellular heat shock protein 72 (eHsp72) concentration has been shown to significantly increase in response to extreme stress. Ultra-endurance events are becoming increasingly popular and place individuals under a prolonged duration of exercise stress, which is exacerbated when undertaken in extreme environmental conditions, particularly extreme heat. The extreme stress imposed upon the body under such conditions places individuals at increased risk of heat illness and cellular damage. The eHsp72 response to ultra-endurance events in extreme environmental conditions has received little attention and thus research is required to understand the heat shock response to such stress. PURPOSE: To investigate the effect of a desert based ultra-marathon (the Marathon des Sables; MDS) on the eHsp72 response in humans. METHODS: Thirteen (three female) competitors (age 42, range: 23-60 years, height 1.74 ± 0.10 m, mass 77.29 ± 12.92 kg, VO2max 55.25 ± 11.96 ml.kg.min-1) provided blood samples via venepuncture for the measurement of eHsp72 concentration on two occasions prior to the race: i) 12 weeks (baseline), and ii) 7 d (pre-race) prior to departure for the MDS, and two further occasions post-race: iii) ~ 6 h post-race and iv) 7 d post-race. The MDS 2015 consisted of 7 consecutive stages, over 7 d, across the Sahara Desert, Morocco, equating to a total distance of 249.4 km. eHsp72 was determined using a commercially available ELISA kit and is displayed as a percentage change from baseline values. RESULTS: Participants completed the ultra-marathon in an average total time of 3043 ± 1002 min. Post-race eHsp72 concentration was 122%, 117% and 108% greater than baseline, pre-race and 7 d post-race, respectively (F3, 45 = 63.348, p < 0.001). CONCLUSION: eHsp72 concentration is significantly elevated in response to 7 consecutive days of prolonged exercise heat stress in extreme environmental conditions and returns to near baseline values within 7 d post race completion

Probiotic Supplementation and Gastrointestinal Endotoxemia Before and After the Marathon Des Sables.

Whilst evidence of increased gastrointestinal endotoxemia (GE) has been previously demonstrated during single-day ultra-endurance events, less is known on the prevalence of GE following extreme ultra-events such as the Marathon Des Sables (MDS). The potential benefit of probiotic formulas on gut integrity during ultra-endurance events also requires further investigation. PURPOSE: To assess the impact of probiotic supplementation with or without glutamine on GE prevalence in runners competing in a multi-day ultra-run (MDS). METHODS: Thirty four healthy participants from the 2015 MDS UK cohort volunteered for a 12 week pre-race intervention and were randomly assigned to either: probiotic (PRO; 100mg.d-1 lactobacillus acidophilus) (age 40 ±3 yrs., weight 79.4 ±2.0kg, VO2max 4.2 ±0.1 L.min-1), probiotic with glutamine (PROglut; 40.5mg.d-1 lactobacillus acidophilus and 900mg.d-1L-glutamine) (age 39 ±2 yrs., weight 70.6 ±4.8 kg, VO2max 4.0 ±0.2 L.min-1) and control (CON) (age 42±3 yrs., weight 79.2 ±3.8 kg, VO2max 4.0 ±0.3 L.min-1). Plasma lipopolysaccharides (LPS) (via Limulus Amebocyte Lysate chromogenic endotoxin quantification) were assessed at weeks 0, 12, post-race and 7 days post-race. Performance data was collated from official timing chips. Data presented as mean ±SE. RESULTS: Mild to moderate GE was prevalent in all groups at baseline (PRO 9.71 ±0.85pg.ml-1, PROglut 9.89 ±1.43 pg.ml-1, CON 9.40 ±0.57 pg.ml-1; P>0.05). Whilst LPS, post intervention, was lower in PROglut there was no significance between groups (9.81 ±1.47pg.ml-1 vs 12.80 ±0.93pg.ml-1 (PRO) vs 11.72 ±1.08 pg.mol-1 (CON); P>0.05). LPS were evidently reduced 6hrs post-race, but not different between groups (PRO: 7.29 ±1.41 pg.ml-1, PROglut: 6.95 ±0.94 pg.ml-1, CON: 9.73 ±1.39 pg.ml-1; P>0.05).Plasma LPS returned to baseline levels 7 days post-race (PRO 7.60 ±0.95 pg.ml-1, PROglut 10.41 ±1.04 pg.ml-1, CON 8.57 ±0.75 pg.ml-1; P>0.05). Race performance (hrs:mins) was not significant between groups, despite PRO and PROglut being ~9hrs faster than CON (41:28±2:31 vs 41:58±4:02 vs 50:43±4:38; P>0.05). CONCLUSION: Moderate GE was prevalent in all groups pre-race and fell significantly during the short-term recovery period. Despite promising results neither probiotic formula had a significant impact on GE or race performance

The effect of long term physical training in the development of mental toughness in recreationally active participants

This study investigated the effect of a long-term training program on the development of mental toughness (MT). Thirty (2 female and 28 male) recreationally active participants (age: 33.53±6.83years; height: 177.41±7.11cm; weight: 78.40±11.94kg; maximal oxygen uptake (VO2max): 47.00±6.48 ml.kg-1.min-1; mean±SD) undertook 6 months of training prior to completing a long-distance triathlon. Participants completed mental toughness questionnaires (MTQ48) at 0, 2, 4, and 6 months of training and 1-month post-race. Data analysis included repeated measures ANOVAs for each MTQ48 variable with consideration to faster and slower finishers. Faster and slower finishers demonstrated non-significant differences (p>0.05) on all MT criteria. There was an effect for time with overall mental toughness (OMT) improving from baseline-post race (cohens d = 0.52; p<0.01) and month 2 post race (d = 0.39; p<0.01), commitment improving from baseline-post race (d = 0.60; p<0.05) and confidence increasing from month 2 post race (d = 0.39; p<0.05). The findings indicate that long term training culminating with competitive experience favourably impacts MT

An exploratory investigation of endotoxin levels in novice long distance triathletes, and the effects of a multi-strain probiotic/prebiotic, antioxidant intervention.

Abstract: Gastrointestinal (GI) ischemia during exercise is associated with luminal permeability and increased systemic lipopolysaccharides (LPS). This study aimed to assess the impact of a multistrain pro/prebiotic/ antioxidant intervention on endotoxin unit levels and GI permeability in recreational athletes. Thirty healthy participants (25 males, 5 females) were randomly assigned either a multistrain pro/prebiotic/ antioxidant (LAB4ANTI; 30 billion CFU.d-1 containing 10 billion CFU.d-1 Lactobacillus acidophilus CUL-60 [NCIMB 30157], 10 billion CFU.d-1 Lactobacillus acidophillus CUL-21 [NCIMB 30156], 9.5 billion CFU.d-1 Bifidobacterium bifidum CUL-20 [NCIMB 30172] and 0.5 billion CFU.d-1 Bifidobacterium animalis subspecies lactis CUL-34 [NCIMB 30153]/ 55.8 mg.d-1 fructooligosaccharides/ 400 mg.d-1 α-lipoic acid, 600 mg.d-1 N-acetyl-carnitine); matched pro/prebiotic (LAB4) or placebo (PL) for 12 weeks preceding a long-distance triathlon. Plasma endotoxin units (via Limulus amebocyte lysate chromogenic quantification) and GI permeability (via 5 hour urinary lactulose (L): mannitol (M) recovery) were assessed at baseline, pre-race and 6 days post-race. Endotoxin unit levels were not significantly different between groups at baseline (LAB4ANTI: 8.20±1.60 pg.ml-1; LAB4: 8.92±1.20 pg.ml-1; PL: 9.72± 2.42 pg.ml-1). The use of a 12 week LAB4ANTI intervention significantly reduced endotoxin units both pre-race (4.37± 0.51 pg.ml-1) and 6 days post-race (5.18±0.57 pg.ml-1; p=0.03, ηp2 = 0.35), but only 6 days post-race with LAB4 (5.01± 0.28 pg.ml-1; p=0.01, ηp2 = 0.43). In contrast, endotoxin units remained unchanged with PL. L:M significantly increased from 0.01±0.01 at baseline to 0.06± 0.01 with PL only (p=0.004, ηp2 = 0.51). Mean race times (hr:min:sec) were not statistically different between groups despite faster times with both pro/prebiotoic groups (LAB4ANTI:13:17:07±34:48; LAB4: 12:47:13±25:06; PL: 14:12:51±29:54; p>0.05). Combined multistrain pro/prebiotic use may reduce endotoxin unit levels, with LAB4ANTI potentially conferring an additive effect via combined GI modulation and antioxidant protection

Assessing the Impact of Probiotic Supplementation and Caloric Periodization on Ultra-endurance Performance and Gastrointestinal Symptoms

Beneficial use of probiotic (PRO) interventions on gastrointestinal endotoxemia (GE) prior to an ultra-endurance triathlon has been previously demonstrated. The prevalence of GE (and whether PRO strategies minimise gastrointestinal (GI) symptoms) relating to multi-day ultra-events is less known. Understanding if nutritional periodization strategies confer similar GI benefits also warrants investigation. PURPOSE: To assess the impact of probiotic supplementation and caloric periodization prior to an extreme ultra-marathon on GI symptoms and race performance. METHODS: Thirty-eight healthy participants were recruited from entrants of the 2015 Marathon Des Sables (age: 42±9yrs; weight: 77.71±10.31kg; VO2max: 52.58±8.66 mL·kg·min-1), and randomly assigned to either: PRO (100mg.d-1 capsulated Lactobacillus acidophilus); CP (caloric periodization of 500kcal above habitual intake on alternate days) or control (CON) for 12 weeks pre-race. Plasma lipopolysaccharides (LPS) via Limulus Amebocyte Lysate chromogenic endotoxin quantification were determined at baseline, pre and post-race. Participants graded duration and severity of GI symptoms through daily questionnaires. Performance times were obtained from accumulated race tracking. Data presented as mean ±SE. RESULTS: Race times (hrs:mins) were 41:28±2:31, 45:12±2:05 and 50:43 ±4:38 for PRO, CP and CON respectively (p>0.05). Overall LPS significantly increased from baseline (10.08±0.53pg.ml-1) to pre-race (13.12±0.74pg.ml-1; p=0.001). Delta LPS pre-race was not different between groups (PRO: 2.94±1.11pg.ml-1; CP: 3.71±1.28pg.ml-1; CON: 2.32±1.26pg.ml-1; p>0.05). Similarly, delta LPS post-race was not different, despite greater reductions in both intervention groups (PRO: -4.57±1.93pg.ml-1; CP: -6.95±1.84pg.ml-1; CON: -2.16±2.21pg.ml-1; p>0.05). GI symptom count favoured PRO (21.8%) compared with CP (41.6%) and CON (36.6%) respectively (p=0.001), although no differences for GI symptom index were reported between groups (p>0.05). CONCLUSIONS: Moderate GE was evident in a UK cohort undertaking a multi-day ultra-marathon. PRO use did not significantly impact on GE prevalence, despite evidence of reduced GI symptoms. Caloric periodization appeared to favour GE recovery post-race, but was not deemed significant

Dopaminergic drug treatment remediates exaggerated cingulate prediction error responses in obsessive-compulsive disorder

Abstract: Rationale: Patients with obsessive-compulsive disorder (OCD) have been found to show exaggerated error responses and prediction error learning signals in a variety of EEG and fMRI tasks, with data converging on the anterior cingulate cortex as a key locus of dysfunction. Considerable evidence has linked prediction error processing to dopaminergic function. Objective: In this study, we investigate potential dopaminergic dysfunction during reward processing in the context of OCD. Methods: We studied OCD patients (n = 18) and controls (n = 18) whilst they learned probabilistic associations between abstract stimuli and monetary rewards in the fMRI scanner involving administration (on separate visits) of a dopamine receptor agonist, pramipexole 0.5 mg; a dopamine receptor antagonist, amisulpride 400 mg; and placebo. We fitted a Q-learning computational model to fMRI prediction error responses; group differences were examined in anterior cingulate and nucleus accumbens regions of interest. Results: There were no significant group, drug, or interaction effects in the number of correct choices; computational modeling suggested a marginally significant difference in learning rates between groups (p = 0.089, partial ƞ2 = 0.1). In the imaging results, there was a significant interaction of group by drug (p = 0.013, partial ƞ2 = 0.13). OCD patients showed abnormally strong cingulate signaling of prediction errors during omission of an expected reward, with unexpected reduction by both pramipexole and amisulpride (p = 0.014, partial ƞ2 = 0.26, 1-β error probability = 0.94). Exaggerated cingulate prediction error signaling to omitted reward in placebo was related to trait subjective difficulty in self-regulating behavior in OCD. Conclusions: Our data support cingulate dysfunction during reward processing in OCD, and bidirectional remediation by dopaminergic modulation, suggesting that exaggerated cingulate error signals in OCD may be of dopaminergic origin. The results help to illuminate the mechanisms through which dopamine receptor antagonists achieve therapeutic benefit in OCD. Further research is needed to disentangle the different functions of dopamine receptor agonists and antagonists during bidirectional modulation of cingulate activation

Examining volumetric gradients based on the frustum surface ratio in the brain in autism spectrum disorder.

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that is accompanied by neurodevelopmental differences in regional cortical volume (CV), and a potential layer-specific pathology. Conventional measures of CV, however, do not indicate how volume is distributed across cortical layers. In a sample of 92 typically developing (TD) controls and 92 adult individuals with ASD (aged 18-52 years), we examined volumetric gradients by quantifying the degree to which CV is weighted from the pial to the white surface of the brain. Overall, the spatial distribution of Frustum Surface Ratio (FSR) followed the gyral and sulcal pattern of the cortex and approximated a bimodal Gaussian distribution caused by a linear mixture of vertices on gyri and sulci. Measures of FSR were highly correlated with vertex-wise estimates of mean curvature, sulcal depth, and pial surface area, although none of these features explained more than 76% variability in FSR on their own. Moreover, in ASD, we observed a pattern of predominant increases in the degree of FSR relative to TD controls, with an atypical neurodevelopmental trajectory. Our findings suggest a more outward-weighted gradient of CV in ASD, which may indicate a larger contribution of supragranular layers to regional differences in CV

Atypical measures of diffusion at the gray-white matter boundary in autism spectrum disorder in adulthood

Autism spectrum disorder (ASD) is a highly complex neurodevelopmental condition that is accompanied by neuroanatomical differences on the macroscopic and microscopic level. Findings from histological, genetic, and more recently in vivo neuroimaging studies converge in suggesting that neuroanatomical abnormalities, specifically around the gray-white matter (GWM) boundary, represent a crucial feature of ASD. However, no research has yet characterized the GWM boundary in ASD based on measures of diffusion. Here, we registered diffusion tensor imaging data to the structural T1-weighted images of 92 adults with ASD and 92 matched neurotypical controls in order to examine between-group differences and group-by-sex interactions in fractional anisotropy and mean diffusivity sampled at the GWM boundary, and at different sampling depths within the superficial white and into the gray matter. As hypothesized, we observed atypical diffusion at and around the GWM boundary in ASD, with between-group differences and group-by-sex interactions depending on tissue class and sampling depth. Furthermore, we identified that altered diffusion at the GWM boundary partially (i.e., ~50%) overlapped with atypical gray-white matter tissue contrast in ASD. Our study thus replicates and extends previous work highlighting the GWM boundary as a crucial target of neuropathology in ASD, and guides future work elucidating etiological mechanisms

Structurally diverse mitochondrial branched chain aminotransferase (BCATm) leads with varying binding modes identified by fragment screening

Inhibitors of mitochondrial branched chain aminotransferase (BCATm), identified using fragment screening, are described. This was carried out using a combination of STD-NMR, thermal melt (Tm), and biochemical assays to identify compounds that bound to BCATm, which were subsequently progressed to X-ray crystallography, where a number of exemplars showed significant diversity in their binding modes. The hits identified were supplemented by searching and screening of additional analogues, which enabled the gathering of further X-ray data where the original hits had not produced liganded structures. The fragment hits were optimized using structure-based design, with some transfer of information between series, which enabled the identification of ligand efficient lead molecules with micromolar levels of inhibition, cellular activity, and good solubility