In-vivo correlations between skin metabolic oscillations and vasomotion in wild-type mice and in a model of oxidative stress

Abstract Arterioles in the cutaneous microcirculation frequently display an oscillatory phenomenon defined vasomotion, consistent with periodic diameter variations in the micro-vessels associated with particular physiological or abnormal conditions. The cellular mechanisms underlying vasomotion and its physiological role have not been completely elucidated. Various mechanisms were demonstrated, based on cell Ca2+ oscillations determined by the activity of channels in the plasma membrane or sarcoplasmic reticulum of vascular cells. However, the possible engagement in vasomotion of cell metabolic oscillations of mitochondrial or glycolytic origin has been poorly explored. Metabolic oscillations associated with the production of ATP energy were previously described in cells, while limited studies have investigated these fluctuations in-vivo. Here, we characterised a low-frequency metabolic oscillator (MO-1) in skin from live wild-type and Nrf2−/− mice, by combination of fluorescence spectroscopy and wavelet transform processing technique. Furthermore, the relationships between metabolic and microvascular oscillators were examined during phenylephrine-induced vasoconstriction. We found a significant interaction between MO-1 and the endothelial EDHF vasomotor mechanism that was reduced in the presence of oxidative stress (Nrf2−/− mice). Our findings suggest indirectly that metabolic oscillations may be involved in the mechanisms underlying endothelium-mediated skin vasomotion, which might be altered in the presence of metabolic disturbance

A randomised controlled study of high intensity exercise as a dishabituating stimulus to improve hypoglycaemia awareness in people with type 1 diabetes:a proof of concept study

Aims/hypothesis Approximately 25% of people with type 1 diabetes have suppressed counterregulatory hormonal and symptomatic responses to insulin-induced hypoglycaemia, which renders them at increased risk of severe, disabling hypoglycaemia. This is called impaired awareness of hypoglycaemia (IAH), the cause of which is unknown. We recently proposed that IAH develops through habituation, a form of adaptive memory to preceding hypoglycaemia. Consistent with this hypothesis, we demonstrated restoration of defective counterregulatory hormonal responses to hypoglycaemia (referred to as dishabituation) in a rodent model of IAH following introduction of a novel stress stimulus (high intensity training [HIT]). In this proof-of-concept study we sought to further test this hypothesis by examining whether a single episode of HIT would amplify counterregulatory responses to subsequent hypoglycaemia in people with type 1 diabetes who had IAH (assessed by Gold score ≥4, modified Clarke score ≥4 or Dose Adjustment For Normal Eating (DAFNE) hypoglycaemia awareness rating 2 or 3). The primary outcome was the difference in adrenaline response to hypoglycaemia following both a single episode of HIT and rest. Methods In this randomised, crossover study 12 participants aged between 18 and 55 years with type 1 diabetes for ≥5 years and an HbA1c < 75 mmol/mol (9%) were recruited. Individuals were randomised using computer generated block randomisation to start with one episode of HIT (4 × 30 s cycle sprints [2 min recovery] at 150% of maximum wattage achieved during V˙O2peak assessment) or rest (control). The following day they underwent a 90 min hyperinsulinaemic–hypoglycaemic clamp study at 2.5 mmol/l with measurement of hormonal counterregulatory response, symptom scores and cognitive testing (four-choice reaction time and digit symbol substitution test). Each intervention and subsequent clamp study was separated by at least 2 weeks. The participants and investigators were not blinded to the intervention or measurements during the study. The investigators were blinded to the primary outcome and blood analysis results. Results All participants (six male and six female, age 19–54 years, median [IQR] duration of type 1 diabetes 24.5 [17.3–29.0] years, mean [SEM] HbA1c 56 [3.67] mmol/mol; 7.3% [0.34%]) completed the study (both interventions and two clamps). In comparison with the rest study, a single episode of HIT led to a 29% increase in the adrenaline (epinephrine) response (mean [SEM]) (2286.5 [343.1] vs 2953.8 [384.9] pmol/l); a significant increase in total symptom scores (Edinburgh Hypoglycaemia Symptom Scale: 24.25 [2.960 vs 27.5 [3.9]; p < 0.05), and a significant prolongation of four-choice reaction time (591.8 [22.5] vs 659.9 [39.86] ms; p < 0.01] during equivalent hypoglycaemia induced the following day. Conclusions/interpretation These findings are consistent with the hypothesis that IAH develops in people with type 1 diabetes as a habituated response and that introduction of a novel stressor can restore, at least partially, the adapted counterregulatory hormonal, symptomatic and cognitive responses to hypoglycaemia.Output Status: Forthcoming/Available Onlin

Is high frequency ultrasound a useful process to add value to out of specification strawberries, raspberries, and blackberries industrially?

Bioactive ingredients can be extracted from surplus soft fruits to add value to them as a fortification ingredient in many new products. Ultrasound‐assisted extraction and spray drying have been heavily studied in the past, with evidence to suggest the positive uptake of these by the food industry. In this paper, strawberries, raspberries and blackberries were examined using a distilled water ‘green’ extraction method with assisted high‐frequency ultrasound and concentration through spray drying. The results showed that crop year and variety had more impact on bioactive concentration than extraction through high‐frequency ultrasound. Two different machines were examined for differences between a cold extraction of water, and a 700 and 2000 Hz industrially relevant probes. Typically, total phenolic content (TPC) was lower in strawberries and blackberries than the control for both methods, however raspberries had a higher GAE mg ml−1 for the 2000 Hz ultrasound than the control. For Radical scavenging (RS) percentage using DPPH Blackberries had higher RS % than the control, whereas strawberries and raspberries had less than the control. These results suggest that ultrasound as a singular method for extracting valuable bioactive ingredients is not suitable with water as the solvent

Neurodevelopmental defects in a mouse model of O-GlcNAc transferase intellectual disability

The addition of O-linked β-N-acetylglucosamine (O-GlcNAc) to proteins (referred to as O-GlcNAcylation) is a modification that is crucial for vertebrate development. O-GlcNAcylation is catalyzed by O-GlcNAc transferase (OGT) and reversed by O-GlcNAcase (OGA). Missense variants of OGT have recently been shown to segregate with an X-linked syndromic form of intellectual disability, OGT-linked congenital disorder of glycosylation (OGT-CDG). Although the existence of OGT-CDG suggests that O-GlcNAcylation is crucial for neurodevelopment and/or cognitive function, the underlying pathophysiologic mechanisms remain unknown. Here we report a mouse line that carries a catalytically impaired OGT-CDG variant. These mice show altered O-GlcNAc homeostasis with decreased global O-GlcNAcylation and reduced levels of OGT and OGA in the brain. Phenotypic characterization of the mice revealed lower body weight associated with reduced body fat mass, short stature and microcephaly. This mouse model will serve as an important tool to study genotype-phenotype correlations in OGT-CDG in vivo and for the development of possible treatment avenues for this disorder.</p

Neurodevelopmental defects in a mouse model of O-GlcNAc transferase intellectual disability

The addition of O-linked β-N-acetylglucosamine (O-GlcNAc) to proteins (referred to as O-GlcNAcylation) is a modification that is crucial for vertebrate development. O-GlcNAcylation is catalyzed by O-GlcNAc transferase (OGT) and reversed by O-GlcNAcase (OGA). Missense variants of OGT have recently been shown to segregate with an X-linked syndromic form of intellectual disability, OGT-linked congenital disorder of glycosylation (OGT-CDG). Although the existence of OGT-CDG suggests that O-GlcNAcylation is crucial for neurodevelopment and/or cognitive function, the underlying pathophysiologic mechanisms remain unknown. Here we report a mouse line that carries a catalytically impaired OGT-CDG variant. These mice show altered O-GlcNAc homeostasis with decreased global O-GlcNAcylation and reduced levels of OGT and OGA in the brain. Phenotypic characterization of the mice revealed lower body weight associated with reduced body fat mass, short stature and microcephaly. This mouse model will serve as an important tool to study genotype-phenotype correlations in OGT-CDG in vivo and for the development of possible treatment avenues for this disorder.</p

High intensity exercise as a dishabituating stimulus restores counterregulatory responses in recurrently hypoglycemic rodents

Hypoglycemia is a major adverse effect of insulin therapy for people with type 1 diabetes (T1D). Profound defects in the normal counterregulatory response to hypoglycemia explain the frequency of hypoglycemia occurrence in T1D. Defective counterregulation results to a large extent from prior exposure to hypoglycemia per se, leading to a condition called impaired awareness of hypoglycemia (IAH), the cause of which is unknown. In the current study, we investigate the hypothesis that IAH develops through a special type of adaptive memory referred to as habituation. To test this hypothesis, we used a novel intense stimulus (high-intensity exercise) to demonstrate two classic features of a habituated response, namely dishabituation and response recovery. We demonstrate that after recurrent hypoglycemia the introduction of a novel dishabituating stimulus (a single burst of high-intensity exercise) in male Sprague-Dawley rats restores the defective hypoglycemia counterregulatory response. In addition, the rats showed an enhanced response to the novel stimulus (response recovery). We make the further observation using proteomic analysis of hypothalamic extracts that high-intensity exercise in recurrently hypoglycemic rats increases levels of a number of proteins linked with brain-derived neurotrophic factor signaling. These findings may lead to novel therapeutic approaches for individuals with T1D and IAH.</jats:p