Interactions Between Insulin and Adenylyl Cyclase Signalling

Hepatocytes immortalised by transfection with SV40 viral DNA have been well studied with respect to marker protein expression and the effects of immortalisation on cell phenotype. Here, a study was undertaken of adenylyl cyclase signalling in one such cell line P9, in order to consider its suitability as a model system for studying this system and insulin action

Solid state differentiation of plasma thiols using a centrifugally activated mercaptobenzothiazole disulfide exchange indicator

The solid state interaction of mono and macromolecular thiols at a disulphide heterocycle is shown to provide a versatile pathway for their speciation

Absent expansion of AXIN2+ hepatocytes and altered physiology in Axin2CreERT2 mice challenges the role of pericentral hepatocytes in homeostatic liver regeneration

Background & Aims: Mouse models of lineage tracing have helped to describe the important subpopulations of hepatocytes responsible for liver regeneration. However, conflicting results have been obtained from different models. Herein, we aimed to reconcile these conflicting reports by repeating a key lineage-tracing study from pericentral hepatocytes and characterising this Axin2CreERT2 model in detail. Methods: We performed detailed characterisation of the labelled population in the Axin2CreERT2 model. We lineage traced this cell population, quantifying the labelled population over 1 year and performed in-depth phenotypic comparisons, including transcriptomics, metabolomics and analysis of proteins through immunohistochemistry, of Axin2CreERT2 mice to WT counterparts. Results: We found that after careful definition of a baseline population, there are marked differences in labelling between male and female mice. Upon induced lineage tracing there was no expansion of the labelled hepatocyte population in Axin2CreERT2 mice. We found substantial evidence of disrupted homeostasis in Axin2CreERT2 mice. Offspring are born with sub-Mendelian ratios and adult mice have perturbations of hepatic Wnt/β-catenin signalling and related metabolomic disturbance. Conclusions: We find no evidence of predominant expansion of the pericentral hepatocyte population during liver homeostatic regeneration. Our data highlight the importance of detailed preclinical model characterisation and the pitfalls which may occur when comparing across sexes and backgrounds of mice and the effects of genetic insertion into native loci. Impact and implications: Understanding the source of cells which regenerate the liver is crucial to harness their potential to regrow injured livers. Herein, we show that cells which were previously thought to repopulate the liver play only a limited role in physiological regeneration. Our data helps to reconcile differing conclusions drawn from results from a number of prior studies and highlights methodological challenges which are relevant to preclinical models more generally

Selection of the appropriate method for the assessment of insulin resistance

Insulin resistance is one of the major aggravating factors for metabolic syndrome. There are many methods available for estimation of insulin resistance which range from complex techniques down to simple indices. For all methods of assessing insulin resistance it is essential that their validity and reliability is established before using them as investigations. The reference techniques of hyperinsulinaemic euglycaemic clamp and its alternative the frequently sampled intravenous glucose tolerance test are the most reliable methods available for estimating insulin resistance. However, many simple methods, from which indices can be derived, have been assessed and validated e.g. homeostasis model assessment (HOMA), quantitative insulin sensitivity check index (QUICKI). Given the increasing number of simple indices of IR it may be difficult for clinicians and researchers to select the most appropriate index for their studies. This review therefore provides guidelines and advices which must be considered before proceeding with a study

Interpreting Biochemical Results - Part 2: Trace elements

Serum TE levels have limitations which make the results difficult to interpret, especially in the acute setting. Because of these limitations, practitioners need to consider factors other than TE levels when assessing TE status. This article discusses five TEs encountered in dietetic practice namely zinc (Zn), copper (Cu), selenium (Se), manganese (Mn) and iron (Fe) suggesting a practical approach to assessing the status of each. For the purposes of description they are considered individually, but in practice they should be considered together. There is a need for new tests of TE status to be developed which are reliable in the acute setting. Until such tests are available, the assessment of TE status will entail some uncertainty and practitioners should be mindful of this when deciding on TE provision

Interpreting Biochemical Results - Part 1: Introduction

The ability to interpret biochemical results is an important skill for the dietitian, one which will become increasingly important as new tests relevant to nutrition are developed. Also, it is often the dietitian who has to act on results as well, either by adjusting nutrient provision or by advising medical colleagues to do so. Although plenty of information has been published on how to interpret biochemical results, the subject is not covered comprehensively in any one publication intended for dietitians. By consolidating some of the available information, this series aims to provide readers with practical guidance which they can apply in the workplace. In the space available, it will focus on the tests most relevant to dietetic practice, including those which can be difficult to interpret and on which dietitians often seek advice from laboratory staff. This first article provides general guidance both on requesting of tests and on interpreting the results

Iron provision in parenteral nutrition

Iron (Fe) is the most abundant trace element (TE) in the body. Although it is an essential nutrient there is no worldwide consensus on whether it should be routinely provided in parenteral nutrition (PN). Indeed, there is a transatlantic difference in practice, Fe being routinely provided in PN in Europe but not in the United States (US). This is reflected in the formulation of the multi-TE (MTE) products used in the two continents. This article discusses the provision of Fe for patients treated with PN, including the arguments for and against providing it in PN itself. It also discusses the assessment of Fe status in patients treated with PN

Interpreting Biochemical Results - Part 3: Lipids

It is important for the dietitian to be able to interpret lipid profiles because the results usually have implications for the nutritional management of patients. The situations in which lipid measurements are requested can be divided into those occurring in non-acute settings − such as primary care and lipid out-patient clinics − and those occurring in acute settings. In non-acute settings, a lipid profile is usually requested when assessing cardiovascular (CV) risk, whereas in acute settings triglyceride alone is often measured for monitoring patients treated with nutrition support. This article discusses the interpretation of lipid results in these two settings

Iron provision in parenteral nutrition

Iron (Fe) is the most abundant trace element (TE) in the body. Although it is an essential nutrient there is no worldwide consensus on whether it should be routinely provided in parenteral nutrition (PN). Indeed, there is a transatlantic difference in practice, Fe being routinely provided in PN in Europe but not in the United States (US). This is reflected in the formulation of the multi-TE (MTE) products used in the two continents. This article discusses the provision of Fe for patients treated with PN, including the arguments for and against providing it in PN itself. It also discusses the assessment of Fe status in patients treated with PN