Faster rehabilitation weight gain is associated with liver fat in adult survivors of childhood severe acute malnutrition

Background Nutritional rehabilitation during severe acute malnutrition (SAM) aims to quickly restore a healthy body weight, but rapid weight gain has been associated with later cardiovascular risk. We hypothesized that faster weight gain during SAM rehabilitation and post-hospitalization is associated with liver fat in adult survivors. Method Jamaican adult survivors of childhood SAM underwent abdominal CT scan to estimate liver fat as mean liver attenuation (MLA) and liver spleen ratio (L/S). Birth weight (BW) and anthropometry measured during, and post-hospitalization were abstracted from admission records. Results We studied 42 marasmus survivors (MRs) and 40 kwashiorkor survivors (KWs). MRs had a lower mean BW (SD) 2.5 (0.8) vs 3.0 (0.7) kg; p=0.01) and were more wasted (p<0.001) and stunted (p=0.03) than KWs on admission to hospital. MRs and KWs had similar rates of rehabilitation weight gain, which was inversely associated with MLA among all survivors of SM (r=-0.246, p=0.029), but only in MRs when assessed by diagnosis (r= -0.449, p=0.004). The association between rehabilitation weight gain and adult liver fat in MRs was not altered by BW, admission wasting or stunting. In KWs, post-hospitalization height gain was inversely associated with MLA (difference = -0.64, 95%CI: -0.64 to -0.13; p=0.006). Conclusions Faster rehabilitation weight gain is associated with liver fat in adult survivors of childhood severe acute malnutrition. The finding that BW did not influence these outcomes may reflect the timing of the nutritional insult in utero. Target weight gain during nutritional rehabilitation may need to be lowered to optimize long-term outcomes in these children

Residual Complex I activity and amphidirectional Complex II operation support glutamate catabolism through mtSLP in anoxia

Anoxia halts oxidative phosphorylation (OXPHOS) causing an accumulation of reduced compounds in the mitochondrial matrix which impedes dehydrogenases. By simultaneously measuring oxygen concentration, NADH autofluorescence, mitochondrial membrane potential and ubiquinone reduction extent in isolated mitochondria in real-time, we demonstrate that Complex I utilized endogenous quinones to oxidize NADH under acute anoxia. 13C metabolic tracing or untargeted analysis of metabolites extracted during anoxia in the presence or absence of site-specific inhibitors of the electron transfer system showed that NAD+ regenerated by Complex I is reduced by the 2-oxoglutarate dehydrogenase Complex yielding succinyl-CoA supporting mitochondrial substrate-level phosphorylation (mtSLP), releasing succinate. Complex II operated amphidirectionally during the anoxic event, providing quinones to Complex I and reducing fumarate to succinate. Our results highlight the importance of quinone provision to Complex I oxidizing NADH maintaining glutamate catabolism and mtSLP in the absence of OXPHOS.</p

LDHB contributes to the regulation of lactate levels and basal insulin secretion in human pancreatic β cells

Using 13C6 glucose labeling coupled to gas chromatography-mass spectrometry and 2D 1H-13C heteronuclear single quantum coherence NMR spectroscopy, we have obtained a comparative high-resolution map of glucose fate underpinning β cell function. In both mouse and human islets, the contribution of glucose to the tricarboxylic acid (TCA) cycle is similar. Pyruvate fueling of the TCA cycle is primarily mediated by the activity of pyruvate dehydrogenase, with lower flux through pyruvate carboxylase. While the conversion of pyruvate to lactate by lactate dehydrogenase (LDH) can be detected in islets of both species, lactate accumulation is 6-fold higher in human islets. Human islets express LDH, with low-moderate LDHA expression and β cell-specific LDHB expression. LDHB inhibition amplifies LDHA-dependent lactate generation in mouse and human β cells and increases basal insulin release. Lastly, cis-instrument Mendelian randomization shows that low LDHB expression levels correlate with elevated fasting insulin in humans. Thus, LDHB limits lactate generation in β cells to maintain appropriate insulin release

LDHB contributes to the regulation of lactate levels and basal insulin secretion in human pancreatic β cells

Using 13C6 glucose labeling coupled to gas chromatography-mass spectrometry and 2D 1H-13C heteronuclear single quantum coherence NMR spectroscopy, we have obtained a comparative high-resolution map of glucose fate underpinning β cell function. In both mouse and human islets, the contribution of glucose to the tricarboxylic acid (TCA) cycle is similar. Pyruvate fueling of the TCA cycle is primarily mediated by the activity of pyruvate dehydrogenase, with lower flux through pyruvate carboxylase. While the conversion of pyruvate to lactate by lactate dehydrogenase (LDH) can be detected in islets of both species, lactate accumulation is 6-fold higher in human islets. Human islets express LDH, with low-moderate LDHA expression and β cell-specific LDHB expression. LDHB inhibition amplifies LDHA-dependent lactate generation in mouse and human β cells and increases basal insulin release. Lastly, cis-instrument Mendelian randomization shows that low LDHB expression levels correlate with elevated fasting insulin in humans. Thus, LDHB limits lactate generation in β cells to maintain appropriate insulin release.</p

BHPR research: qualitative1. Complex reasoning determines patients' perception of outcome following foot surgery in rheumatoid arhtritis

Background: Foot surgery is common in patients with RA but research into surgical outcomes is limited and conceptually flawed as current outcome measures lack face validity: to date no one has asked patients what is important to them. This study aimed to determine which factors are important to patients when evaluating the success of foot surgery in RA Methods: Semi structured interviews of RA patients who had undergone foot surgery were conducted and transcribed verbatim. Thematic analysis of interviews was conducted to explore issues that were important to patients. Results: 11 RA patients (9 ♂, mean age 59, dis dur = 22yrs, mean of 3 yrs post op) with mixed experiences of foot surgery were interviewed. Patients interpreted outcome in respect to a multitude of factors, frequently positive change in one aspect contrasted with negative opinions about another. Overall, four major themes emerged. Function: Functional ability & participation in valued activities were very important to patients. Walking ability was a key concern but patients interpreted levels of activity in light of other aspects of their disease, reflecting on change in functional ability more than overall level. Positive feelings of improved mobility were often moderated by negative self perception ("I mean, I still walk like a waddling duck”). Appearance: Appearance was important to almost all patients but perhaps the most complex theme of all. Physical appearance, foot shape, and footwear were closely interlinked, yet patients saw these as distinct separate concepts. Patients need to legitimize these feelings was clear and they frequently entered into a defensive repertoire ("it's not cosmetic surgery; it's something that's more important than that, you know?”). Clinician opinion: Surgeons' post operative evaluation of the procedure was very influential. The impact of this appraisal continued to affect patients' lasting impression irrespective of how the outcome compared to their initial goals ("when he'd done it ... he said that hasn't worked as good as he'd wanted to ... but the pain has gone”). Pain: Whilst pain was important to almost all patients, it appeared to be less important than the other themes. Pain was predominately raised when it influenced other themes, such as function; many still felt the need to legitimize their foot pain in order for health professionals to take it seriously ("in the end I went to my GP because it had happened a few times and I went to an orthopaedic surgeon who was quite dismissive of it, it was like what are you complaining about”). Conclusions: Patients interpret the outcome of foot surgery using a multitude of interrelated factors, particularly functional ability, appearance and surgeons' appraisal of the procedure. While pain was often noted, this appeared less important than other factors in the overall outcome of the surgery. Future research into foot surgery should incorporate the complexity of how patients determine their outcome Disclosure statement: All authors have declared no conflicts of interes

Biotic and environmental dynamics through the Late Jurassic-Early Cretaceous transition: evidence for protracted faunal and ecological turnover

The Late Jurassic to Early Cretaceous interval represents a time of environmental upheaval and cataclysmic events, combined with disruptions to terrestrial and marine ecosystems. Historically, the Jurassic/Cretaceous (J/K) boundary was classified as one of eight mass extinctions. However, more recent research has largely overturned this view, revealing a much more complex pattern of biotic and abiotic dynamics than has previously been appreciated. Here, we present a synthesis of our current knowledge of Late Jurassic–Early Cretaceous events, focusing particularly on events closest to the J/K boundary. We find evidence for a combination of short-term catastrophic events, large-scale tectonic processes and environmental perturbations, and major clade interactions that led to a seemingly dramatic faunal and ecological turnover in both the marine and terrestrial realms. This is coupled with a great reduction in global biodiversity which might in part be explained by poor sampling. Very few groups appear to have been entirely resilient to this J/K boundary ‘event’, which hints at a ‘cascade model’ of ecosystem changes driving faunal dynamics. Within terrestrial ecosystems, larger, more-specialised organisms, such as saurischian dinosaurs, appear to have suffered the most. Medium-sized tetanuran theropods declined, and were replaced by larger-bodied groups, and basal eusauropods were replaced by neosauropod faunas. The ascent of paravian theropods is emphasised by escalated competition with contemporary pterosaur groups, culminating in the explosive radiation of birds, although the timing of this is obfuscated by biases in sampling. Smaller, more ecologically diverse terrestrial non-archosaurs, such as lissamphibians and mammaliaforms, were comparatively resilient to extinctions, instead documenting the origination of many extant groups around the J/K boundary. In the marine realm, extinctions were focused on low-latitude, shallow marine shelf-dwelling faunas, corresponding to a significant eustatic sea-level fall in the latest Jurassic. More mobile and ecologically plastic marine groups, such as ichthyosaurs, survived the boundary relatively unscathed. High rates of extinction and turnover in other macropredaceous marine groups, including plesiosaurs, are accompanied by the origin of most major lineages of extant sharks. Groups which occupied both marine and terrestrial ecosystems, including crocodylomorphs, document a selective extinction in shallow marine forms, whereas turtles appear to have diversified. These patterns suggest that different extinction selectivity and ecological processes were operating between marine and terrestrial ecosystems, which were ultimately important in determining the fates of many key groups, as well as the origins of many major extant lineages. We identify a series of potential abiotic candidates for driving these patterns, including multiple bolide impacts, several episodes of flood basalt eruptions, dramatic climate change, and major disruptions to oceanic systems. The J/K transition therefore, although not a mass extinction, represents an important transitional period in the co-evolutionary history of life on Earth

Examining the cell biology of the NIMA-related kinases

The NIMA-related kinases are the least well characterised of the so-called cell cycle kinases. Mounting evidence suggests some members of the family have roles in centrosome splitting, chromosome segregation, DNA damage response and regulation of cilia. Other members of the family are implicated in cystic kidney diseases, polycystic ovary syndrome and cancer. In this thesis I addressed specific questions related to three Neks: (i) NEK8 due to its role in cystic kidney diseases (ii) NEK4 because of its unusual sub-cellular localisation and (iii) CNK6 a potential link between cilia and the cell cycle. I developed the tools necessary for the identification of NEK8 substrates. I showed NEK4 localises to the distal end of the mother centriole. Neither kinase activity, nor the phosphorylation state of thr526 are necessary for this localisation. CNK6, initially identified in the flagellar proteome, does not localise to flagella and may be essential for Chlamydomonas reinhardtii survival

Examining the role of Myt3 in beta-cell function and survival

Diabetes is a chronic disease that results from the body’s inability to properly control circulating blood glucose levels. The loss of glucose homeostasis can arise either from a loss of β-cell mass because of immune-cell mediated attack, as in T1D, and/or from dysfunction of individual β-cells (in conjunction with target organ insulin resistance), as in T2D. Despite advances in current therapies to treat diabetes we are still far from a cure, and a greater understanding of the transcriptional pathways regulating islet development, function and survival will be critical if we are to achieve this goal. The aims of this dissertation were to delineate the role of the transcription factor Myt3 in β-cell function and survival. To this end we first examined the regulatory mechanisms involved in the control of Myt3 expression. We demonstrate that Myt3 expression is dependent on important islet transcription factors, including Foxa2, Pdx1 and Neurod1. We further established that Myt3 expression is regulated both developmentally, likely by the aforementioned factors, and by external stimuli including glucose and cytokines. From these early results we explored the effect of Myt3 suppression on the function and survival of β-cells. Our data show that reduced levels of Myt3 impair the ability of β-cells to migrate, which has potential implications for islet formation during development and compensatory islet neogenesis during diabetes progression, and leads to increased apoptosis. Lastly, to confirm these effects in vivo we studied the effects of Myt3 suppression in syngeneic islet transplants. Our data show that reduced Myt3 results in increased cell death in the grafts. Collectively, the data presented in this dissertation are an important step in clarifying the regulatory networks responsible for β-cell development, function and survival, and point to Myt3 as a potential therapeutic target for improving functional β-cell mass.Medicine, Faculty ofGraduat