The impact of diet in early life on adipose tissue growth and development in sheep

Adipose tissue is found in two main forms: white (WAT), which stores energy; and brown (BAT), which dissipates energy as heat by means of a unique mitochondrial protein, UCP1. In large mammals, BAT is rapidly replaced by WAT after birth, but it has recently been found that functional BAT is present in human adults, which raises the possibility that it could be manipulated to burn off excess fat. The main aim of this thesis was to investigate, using sheep as a model, the effect of early nutritional interventions on fat mass and on the expression in adipose tissue of genes involved in adipogenesis, metabolism, thermogenesis and development. A secondary aim was to study their ontogeny in sternal adipose tissue. Study A examined the effect of fat supplements given to lactating ewes on the sternal adipose tissue of their offspring. Ewes were allocated to one of three feeding groups, one control and two supplemented (sunflower or canola oil), for 28 days after parturition, and their lambs were sampled at 7 and 28 days of age. Study B investigated the effect of late gestational and postnatal diet on the sternal and subcutaneous adipose tissue of 6 month-old lambs. Twin-pregnant ewes were divided into three dietary groups for the last 6 weeks of gestation: undernourished, control or overnourished. One lamb from each twin pair was fed a control diet, and the other a high-carbohydrate, high-fat (HCHF) diet. In the first month after birth, changes in gene expression in sternal adipose tissue were comparable to those previously described in perirenal adipose tissue, with the expression of most thermogenic genes declining to almost undetectable levels by 28 days of age. There was a disparity in the expression profiles of the two principal regulators of adipogenesis, PPARγ and C/EBPα, with expression of the former increasing with age, and that of the latter peaking at 7 days of age. A sunflower, but not canola, oil supplement fed to lactating ewes increased the relative adipose tissue weight of female, but not male, lambs at 28 days of age. Both supplements increased the plasma concentration of leptin at 7 and 28 days of age in females, but not males. Supplementation had a greater effect on gene expression at 7 than at 28 days of age, but no overall pattern emerged. Maternal undernutrition reduced birth weight in males, but not females, although body weight was unaffected by 6 months of age. A postnatal HCHF diet increased fat mass in all adipose tissue depots tested, and reduced expression of most adipogenic and metabolic genes in sternal and subcutaneous adipose tissue by around 50 %. Expression of thermogenic genes was barely detectable in either tissue at 6 months of age. In conclusion, expression of thermogenic genes in sternal adipose tissue declines with age, a response that is unaffected by maternal fat supplementation during lactation or a sustained postnatal HCHF diet

Combined bezafibrate and medroxyprogesterone acetate: potential novel therapy for acute myeloid leukaemia

Background: The majority of acute myeloid leukaemia (AML) patients are over sixty years of age. With current treatment regimens, survival rates amongst these, and also those younger patients who relapse, remain dismal and novel therapies are urgently required. In particular, therapies that have anti-leukaemic activity but that, unlike conventional chemotherapy, do not impair normal haemopoiesis. Principal Findings: Here we demonstrate the potent anti-leukaemic activity of the combination of the lipid-regulating drug bezafibrate (BEZ) and the sex hormone medroxyprogesterone acetate (MPA) against AML cell lines and primary AML cells. The combined activity of BEZ and MPA (B/M) converged upon the increased synthesis and reduced metabolism of prostaglandin D2 (PGD2) resulting in elevated levels of the downstream highly bioactive, anti-neoplastic prostaglandin 15-deoxy Δ12,14 PGJ2 (15d-PGJ2). BEZ increased PGD2 synthesis via the generation of reactive oxygen species (ROS) and activation of the lipid peroxidation pathway. MPA directed prostaglandin synthesis towards 15d-PGJ2 by inhibiting the PGD2 11β -ketoreductase activity of the aldo-keto reductase AKR1C3, which metabolises PGD2 to 9α11β-PGF2α. B/M treatment resulted in growth arrest, apoptosis and cell differentiation in both AML cell lines and primary AML cells and these actions were recapitulated by treatment with 15d-PGJ2. Importantly, the actions of B/M had little effect on the survival of normal adult myeloid progenitors. Significance: Collectively our data demonstrate that B/M treatment of AML cells elevated ROS and delivered the anti-neoplastic actions of 15d-PGJ2. These observations provide the mechanistic rationale for the redeployment of B/M in elderly and relapsed AML

Comparison of short- and long-term humoral immune responses to pneumococcal polysaccharide and glycoconjugate vaccines in an HIV-infected population

Background: Immunisation is recommended internationally to protect against pneumococcal infections in HIV-infected adults. However, vaccination schedule designs are mostly based on studies of initial rather than long-term antibody responses. This UK observational study investigated the short- and long-term antibody responses to polysaccharide and glycoconjugate pneumococcal vaccines in an adult HIV-infected cohort.Methods: We studied a subgroup of 152 of 839 participants from the AIR (Assessment of Immune Responses to Routine Immunisations in HIV-infected Adults, ISRCTN95588307) study that had received pneumococcal vaccinations and had blood samples collected pre- and post-vaccination, as well as at least annually for four subsequent calendar years. Patients received either Pneumovax-23 (PPV, N = 89) or Prevenar-13 (PCV, N = 63) as their primary vaccine, with immunity assessed by measuring IgG antibody concentrations for 12 pneumococcal polysaccharide serotypes (PnPS). The primary outcome was achieving IgG antibody concentrations above the recommended World Health Organisation (WHO) threshold of 0.35 µg/mL for at least 8/12 of the PnPS assessed (WHO≥8/12PnPS). Patients who did not achieve WHO≥8/12PnPS after the primary vaccination were offered further vaccination with PCV; booster vaccinations with PCV were additionally offered to those where antibody levels subsequently fell below the WHO≥8/12PnPS threshold.Results: Patients receiving PCV as their primary pneumococcal vaccine were significantly more likely to achieve WHO≥8/12PnPS after a single vaccine dose than those receiving PPV (54% vs. 33%, p = 0.012). This difference persisted following booster vaccination with PCV, with cumulative rates of WHO≥8/12PnPS in those receiving PCV vs. PPV as the primary vaccine of 88% vs. 67% and 100% vs. 85% after receiving up to one and two booster vaccinations, respectively. Where WHO≥8/12PnPS was achieved, this persisted significantly longer in those receiving PCV as their primary vaccine compared to PPV (median: 23.5 vs. 11.1 months; p = 0.010).Conclusions: Immunisation with PCV resulted in quantitatively greater antibody responses than immunisation with PPV in a cohort of HIV-infected UK adults. Individuals receiving PCV as their primary vaccine required fewer total pneumococcal vaccine doses to achieve WHO≥8/12PnPS and experienced greater duration of time above this threshold than those with PPV as the primary vaccine. However, the median longevity of both vaccine responses was relatively short, which supports the use of ongoing booster doses using high-valency glycoconjugate vaccines to sustain WHO≥8/12PnPS threshold antibody levels

Spatio-Temporal Dependence of the Signaling Response in Immune-Receptor Trafficking Networks Regulated by Cell Density: A Theoretical Model

Cell signaling processes involve receptor trafficking through highly connected networks of interacting components. The binding of surface receptors to their specific ligands is a key factor for the control and triggering of signaling pathways. In most experimental systems, ligand concentration and cell density vary within a wide range of values. Dependence of the signal response on cell density is related with the extracellular volume available per cell. This dependence has previously been studied using non-spatial models which assume that signaling components are well mixed and uniformly distributed in a single compartment. In this paper, a mathematical model that shows the influence exerted by cell density on the spatio-temporal evolution of ligands, cell surface receptors, and intracellular signaling molecules is developed. To this end, partial differential equations were used to model ligand and receptor trafficking dynamics through the different domains of the whole system. This enabled us to analyze several interesting features involved with these systems, namely: a) how the perturbation caused by the signaling response propagates through the system; b) receptor internalization dynamics and how cell density affects the robustness of dose-response curves upon variation of the binding affinity; and c) that enhanced correlations between ligand input and system response are obtained under conditions that result in larger perturbations of the equilibrium . Finally, the results are compared with those obtained by considering that the above components are well mixed in a single compartment

Ontogeny and thermogenic role for sternal fat in female sheep

Brown adipose tissue acting through a unique uncoupling protein (UCP1) has a critical role in preventing hypothermia in new-born sheep but is then considered to rapidly disappear during postnatal life. The extent to which the anatomical location of fat influences postnatal development and thermogenic function, particularly following feeding, in adulthood, are not known and were both examined in our study. Changes in gene expression of functionally important pathways (i.e. thermogenesis, development, adipogenesis and metabolism) were compared between sternal and retroperitoneal fat depots together with a representative skeletal muscle over the first month of postnatal life, coincident with the loss of brown fat and accumulation of white fat. In adult sheep, implanted temperature probes were used to characterise the thermogenic response of fat and muscle to feeding and the effects of reduced or increased adiposity. UCP1 was more abundant within sternal than retroperitoneal fat and was only retained in the sternal depot of adults. Distinct differences in the abundance of gene pathway markers were apparent between tissues, with sternal fat exhibiting some similarities with muscle that were not apparent in the retroperitoneal depot. In adults, the post-prandial rise in temperature was greater and more prolonged in sternal than retroperitoneal fat and muscle, a difference that was maintained with altered adiposity. In conclusion, sternal adipose tissue retains UCP1 into adulthood when it shows a greater thermogenic response to feeding than muscle and retroperitoneal fat. Sternal fat may be more amenable to targeted interventions that promote thermogenesis in large mammals

The impact of diet in early life on adipose tissue growth and development in sheep

Adipose tissue is found in two main forms: white (WAT), which stores energy; and brown (BAT), which dissipates energy as heat by means of a unique mitochondrial protein, UCP1. In large mammals, BAT is rapidly replaced by WAT after birth, but it has recently been found that functional BAT is present in human adults, which raises the possibility that it could be manipulated to burn off excess fat. The main aim of this thesis was to investigate, using sheep as a model, the effect of early nutritional interventions on fat mass and on the expression in adipose tissue of genes involved in adipogenesis, metabolism, thermogenesis and development. A secondary aim was to study their ontogeny in sternal adipose tissue. Study A examined the effect of fat supplements given to lactating ewes on the sternal adipose tissue of their offspring. Ewes were allocated to one of three feeding groups, one control and two supplemented (sunflower or canola oil), for 28 days after parturition, and their lambs were sampled at 7 and 28 days of age. Study B investigated the effect of late gestational and postnatal diet on the sternal and subcutaneous adipose tissue of 6 month-old lambs. Twin-pregnant ewes were divided into three dietary groups for the last 6 weeks of gestation: undernourished, control or overnourished. One lamb from each twin pair was fed a control diet, and the other a high-carbohydrate, high-fat (HCHF) diet. In the first month after birth, changes in gene expression in sternal adipose tissue were comparable to those previously described in perirenal adipose tissue, with the expression of most thermogenic genes declining to almost undetectable levels by 28 days of age. There was a disparity in the expression profiles of the two principal regulators of adipogenesis, PPARγ and C/EBPα, with expression of the former increasing with age, and that of the latter peaking at 7 days of age. A sunflower, but not canola, oil supplement fed to lactating ewes increased the relative adipose tissue weight of female, but not male, lambs at 28 days of age. Both supplements increased the plasma concentration of leptin at 7 and 28 days of age in females, but not males. Supplementation had a greater effect on gene expression at 7 than at 28 days of age, but no overall pattern emerged. Maternal undernutrition reduced birth weight in males, but not females, although body weight was unaffected by 6 months of age. A postnatal HCHF diet increased fat mass in all adipose tissue depots tested, and reduced expression of most adipogenic and metabolic genes in sternal and subcutaneous adipose tissue by around 50 %. Expression of thermogenic genes was barely detectable in either tissue at 6 months of age. In conclusion, expression of thermogenic genes in sternal adipose tissue declines with age, a response that is unaffected by maternal fat supplementation during lactation or a sustained postnatal HCHF diet

Changing chains : three case studies of the change management needed to reconfigure European supply chains

Purpose: Many supply chain reconfiguration programs are launched each year. Despite a wealth of knowledge existing in the general management domain, there has been little work within the supply chain management domain on change. That which does exist deals with change to a technical – as opposed to non-technical – system. This leaves out many of the social and behavioral aspects of change. This paper aims to address this gap. Design/methodology/approach: The paper synthesized the general management and supply chain literature on change to create a framework to explore change within three supply chains. A multiple case study approach was adopted for the research. Longitudinal and quasi-longitudinal data were gathered and template analysis utilized to explore the cases contexts and the design choices they made in each of the change programmes. Findings: In all three cases, the change is non-linear and required re-planning and learning throughout the change effort to build the capacity and capability for change. In all three cases, the success of the change is facilitated through the use of cross-functional teams. Originality/value: Change leaders were involved in the research through co-authorship and a unique set of cross-case lessons learned were generated. The framework used in the analysis incorporates considerations previously ignored in the supply chain literature, including the non-linear, non-processual nature of change