Intra-islet glucagon signalling regulates beta-cell connectivity, first-phase insulin secretion and glucose homoeostasis.

OBJECTIVE: Type 2 diabetes (T2D) is characterised by the loss of first-phase insulin secretion. We studied mice with ß-cell selective loss of the glucagon receptor (Gcgrfl/fl X Ins-1Cre), to investigate the role of intra-islet glucagon receptor (GCGR) signalling on pan-islet [Ca2+]I activity and insulin secretion. METHODS: Metabolic profiling was conducted on Gcgrß-cell-/- and littermate controls. Crossing with GCaMP6f (STOP flox) animals further allowed for ß-cell specific expression of a fluorescent calcium indicator. These islets were functionally imaged in vitro and in vivo. Wild-type mice were transplanted with islets expressing GCaMP6f in ß-cells into the anterior eye chamber and placed on a high fat diet. Part of the cohort received a glucagon analogue (GCG-analogue) for 40 days and the control group were fed to achieve weight matching. Calcium imaging was performed regularly during the development of hyperglycaemia and in response to GCG-analogue treatment. RESULTS: Gcgrß-cell-/- mice exhibited higher glucose levels following intraperitoneal glucose challenge (control 12.7 mmol/L ± 0.6 vs. Gcgrß-cell-/- 15.4 mmol/L ± 0.0 at 15 min, p = 0.002); fasting glycaemia was not different to controls. In vitro, Gcgrß-cell-/- islets showed profound loss of pan-islet [Ca2+]I waves in response to glucose which was only partially rescued in vivo. Diet induced obesity and hyperglycaemia also resulted in a loss of co-ordinated [Ca2+]I waves in transplanted islets. This was reversed with GCG-analogue treatment, independently of weight-loss (n = 8). CONCLUSION: These data provide novel evidence for the role of intra-islet GCGR signalling in sustaining synchronised [Ca2+]I waves and support a possible therapeutic role for glucagonergic agents to restore the insulin secretory capacity lost in T2D.

Sequencing and functional assessment of hPXR (NR1I2) variants in intrahepatic cholestasis of pregnancy.

1. The purpose of this study was to evaluate the role of coding variation in hPXR (NR1I2) in intrahepatic cholestasis of pregnancy (ICP) and to functionally asses the response of PXR variants to ligands of interest in ICP. 2. The coding region of hPXR was sequenced in a cohort of 121 Caucasian ICP patients and exon 2 was sequenced in an additional 226 cases. Reporter assays were used to evaluate the function of all known hPXR variants in response to the secondary bile acid lithocholic acid and therapeutic agents rifampicin, ursodeoxycholic acid and dexamethasone. 3. Two coding single nucleotide polymorphisms (C79T and G106A) were detected in the ICP cohort at frequencies consistent with healthy populations. These do not alter hPXR function in response to ligands of interest to ICP. Analysis of all known coding hPXR variants demonstrates that while subtle changes in experimental design mask or may unveil the functional effects of genetic variation, these are not maintained in a standard functional assay. 4. Coding genetic variation in hPXR does not contribute to the aetiology of ICP in Caucasian populations.

Raised levels of plasma interleukin-1beta in major and postviral depression.

OBJECTIVE: Interleukin-1beta (IL-1beta) is released as part of the acute phase immune response and can directly stimulate the release of corticotrophin-releasing hormone and thus induce hypothalamic pituitary adrenal axis hyperactivity. Major depression has been shown to be accompanied by both an acute phase immune response, including raised IL-1beta production and hypothalamic pituitary adrenal axis hyperactivity. In this study the possible role of IL-1beta in major depression and postviral depression was investigated. METHOD: Plasma IL-1beta levels were measured in four groups; patients suffering from postviral depression (n= 17), patients with major depression (n = 20), subjects who were postviral and euthymic (n= 12) and normal controls (n = 20). RESULTS: IL-1beta serum concentrations were significantly elevated in both groups of depressed patients compared to controls. The serum concentrations of IL-1beta were higher in the postviral group than in the major depression group; this difference was not significant. CONCLUSION: These data confirm previous suggestions of elevated IL-1beta levels in major depression and postviral depression. IL-1beta is known to induce depressive symptoms as well as sickness behaviour and may contribute to the hypothalamic pituitary adrenal axis hyperactivity found in mood disorders.

Assessment of the methods available for testing sensation in leprosy patients in a rural setting.

The aim of this study was to assess the efficacy, practicality and patient understanding of 5 methods used for testing sensation in leprosy patients, in a rural setting. The tests used were the WHO test, cottonwool, pin-prick, monofilaments and the biothesiometer. We concentrated on testing sensation in the hands, and the various tests were carried out on 75 patients and 32 controls, all taken from villagers living at Kindwitwi Leprosy Village, Tanzania. Our results showed that although the WHO test, cottonwool and pin-prick were all easy to use, cheap and well accepted they were not sensitive enough to be of any practical value. We found that the monofilaments, as well as being cheap and easy to use, had great potential value, as the 2-g monofilament could be used as a threshold value (indicative of leprosy, but not diagnostic) for protective sensation with a combined false-positive and false-negative value of only 4%. Finally, the biothesiometer was found to be a precise test that can accurately identify leprosy patients from controls and identify patients at risk of ulceration. It was, however, associated with its own problems, chiefly those of expense and its need of electricity, although we found this latter problem could be easily and relatively cheaply solved by the use of a solar powered recharger (Appendix).

The effect of footwear on sensory testing in leprosy.

The aim of this study was to identify the effect of footwear on sensory testing in leprosy. This was achieved by using 3 methods of sensory testing within 1 district of East Africa. We included 72 leprosy patients and 36 patients (nonleprosy patients) in the study and these were subdivided into 2 groups, depending on whether they normally wore shoes or went barefoot. The methods used were the WHO sensory test, graded monofilaments and the biothesiometer. The results showed significant differences in the threshold levels between both groups of patients with the biothesiometer and monofilaments, demonstrating the importance of having separate values when screening for leprosy and assessing which patients are at the most risk of developing ulcers. The importance of having quantitative methods of testing was also demonstrated, as only then can the results be sufficiently standardized to identify the at-risk groups and also be sufficiently sensitive to differentiate between shoe wearing and nonshoe wearing patients.