A thyroxine absorption test followed by weekly thyroxine administration: a method to assess non-adherence to treatment.

OBJECTIVE: For patients who remain hypothyroid despite the administration of what would seem adequate doses of levothyroxine (L-T4), the underlying cause can be difficult to determine. The possibility of a biological cause should first be explored; however, in the majority of cases, poor adherence to medication is likely to be the main cause of treatment failure. When non-adherence is suspected but not volunteered, options to confirm the suspicion are limited. In this study, we identified patients for whom known drugs and pathological causes of L-T4 malabsorption were excluded, and despite often high doses of L-T4, the patients remained hypothyroid. DESIGN: Using a weight-determined oral L-T4 bolus administration, absorption was initially assessed in 23 patients. In nearly all patients, this was shown to be maximal at 120 min post-ingestion. This was then followed by the continued administration of a weekly T4 bolus for a 4-week period after which TSH and free T4 (fT4) levels were recorded. RESULTS: All patients showed a rise in fT4 at 120 min following the administration of the L-T4 bolus, with a mean increase of 54±3% from baseline. Following the treatment period, using an equivalent weekly L-T4 dose, which was significantly less than that of the daily dose taken by the patients before the test, TSH reduced from baseline in ~75% of cases. CONCLUSION: Using this combination of tests allows significant malabsorptive problems to be identified first and then potential non-adherence to be demonstrated. A management plan can then be implemented to increase adherence, aiming to improve treatment outcomes.

The role of interventional radiology and imaging in pancreatic islet cell transplantation.

Pancreatic islet cell transplantation (PICT) is a novel treatment for patients with insulin-dependent diabetes who have inadequate glycaemic control or hypoglycaemic unawareness, and who suffer from the microvascular/macrovascular complications of diabetes despite aggressive medical management. Islet transplantation primarily aims to improve the quality of life for type 1 diabetic patients by achieving insulin independence, preventing hypoglycaemic episodes, and reversing hypoglycaemic unawareness. The islet cells for transplantation are extracted and purified from the pancreas of brain-stem dead, heart-beating donors. They are infused into the recipient's portal vein, where they engraft into the liver to release insulin in order to restore euglycaemia. Initial strategies using surgical access to the portal vein have been superseded by percutaneous access using interventional radiology techniques, which are relatively straightforward to perform. It is important to be vigilant during the procedure in order to prevent major complications, such as haemorrhage, which can be potentially life-threatening. In this article we review the history of islet cell transplantation, present an illustrated review of our experience with islet cell transplantation by describing the role of imaging and interventional radiology, and discuss current research into imaging techniques for monitoring graft function.

Longevity of human islet α- and ß-cells.

Pancreatic islet cell regeneration is considered to be important in the onset and progression of diabetes and as a potential cell therapy. Current hypotheses, largely based on rodent studies, indicate continuous turnover and plasticity of α- and ß-cells in adults; cell populations in rodents respond to increased secretory demand in obesity (30-fold ß-cell increase) and pregnancy. Turnover and plasticity of islet cells decrease in mice within >1 year. In man, morphometric observations on postmortem pancreas have indicated that the cellular expansion is much smaller than the increased insulin secretion that accompanies obesity. Longevity of ß-cells in humans >20-30 years has been shown by (14) C measurements and bromo-deoxyuridine (BrdU) incorporation and there is an age-related decline in the expression of proteins associated with cell division and regeneration including cyclin D3 and PDX-1. Quantitative estimation and mathematical modelling of the longevity marker, cellular lipofuscin body content, in islets of subjects aged 1-84 years indicated an age-related increase and that 97% of the human ß-cell population was established by the age of 20. New data show that human α-cell lipofuscin content is less than that seen in ß-cells, but the age-related accumulation is similar; lipofuscin-positive (aged) cells form ≥ 95% of the population after 20 years. Increased turnover of cellular organelles such as mitochondria and endoplasmic reticulum could contribute to lipofuscin accumulation with age in long-lived cells. Induction of regeneration of human islet cells will require understanding of the mechanisms associated with age-related senescence.

Regulation of glucagon secretion by glucose: paracrine, intrinsic or both?

Glucagon secretion is regulated by glucose but the mechanisms involved remain hotly debated. Both intrinsic (within the α-cell itself) and paracrine (mediated by factors released ß- and/or δ-cells) have been postulated. Glucagon secretion is maximally suppressed by glucose concentrations that do not affect insulin and somatostatin secretion, a finding that highlights the significance of intrinsic regulation of glucagon secretion. Experiments on islets from mice lacking functional ATP-sensitive potassium channels (K(ATP)-channels) indicate that these channels are critical to the α-cell's capacity to sense changes in extracellular glucose. Here, we review recent data on the intrinsic and paracrine regulation of glucagon secretion in human pancreatic islets. We propose that glucose-induced closure of the K(ATP)-channels, via membrane depolarization, culminates in reduced electrical activity and glucagon secretion by voltage-dependent inactivation of the ion channels involved in action potential firing. We further demonstrate that glucagon secretion measured in islets isolated from donors with type-2 diabetes is reduced at low glucose and that glucose stimulates rather than inhibits secretion in these islets. We finally discuss the relative significance of paracrine and intrinsic regulation in the fed and fasted states and propose a unifying model for the regulation of glucagon secretion that incorporates both modes of control.

An e-mail GP advisory service: a more efficient way of dealing with clinical enquiries.

Good communication between primary and secondary care is vital for patient management. This article describes how an e-mail enquiry service for endocrinology and diabetes was established within one hospital and the potential benefits that it offers.

Inflammatory response, reactive oxygen species, programmed (necrotic-like and apoptotic) cell death and cancer.

In this short review we attempt to establish and/or strengthen connections between clinical, inflammatory manifestation of cancer, inflammatory processes driven by lipoxy-metabolites and their contribution to immortalized phenotype and apoptosis inhibition. Particularly the resemblance between symptoms of inflammation and signs associated with cancer chemotherapy and/or cytokine therapy is illustrated. In this context the role of apoptosis and necrosis in inflammation as well as the role of RedOx processes and lipid-oxidizing enzymes particularly cyclooxygenase-2 (COX-2) and also to lesser extend the 5-lipooxygenase (5-LOX) is highlighted. The multitude of biological effects of reactive oxygen species is shortly summarized and some aspects of it are being discussed in greater detail. Apoptotic cell death is discussed in the context of the "resolve-phase" of an inflammatory response. The disturbance of apoptosis is mainly deliberated in the framework of insufficient removal of immuno-effector cells that may cause autoimmunity. The role of COX-2 in apoptosis resistance is being highlighted mainly in the context of malignant transformation. The mechanism of cell death (apoptotic or necrotic) and its influence on the immune system and potential benefits of necrotic cell death induction during cancer chemotherapy is indicated.

Identification and characterisation of PmaCI an endonuclease of novel specificity from Pseudomonas maltophila.

We report the use of MonoQ FPLC (Fast Protein Liquid Chromatography) for the rapid purification of a novel Type II restriction endonuclease PmaCI, from Pseudomonas maltophila, which recognises the sequence 5'-CAC decreases GTG-3'. The resulting enzyme is free of other nucleases to a level suitable for its characterisation by multiple-substrate digestion and DNA sequencing techniques. This method appears to be widely applicable and we have used it for the isolation of restriction endonucleases of comparable purity from a range of other organisms. Also described is a rapid method for screening a library of small inserted regions in recombinant M13 molecules for the presence and subsequent screening of restriction sites of interest.

Effect of prazosin on renal function in chronic congestive cardiac failure.

Prazosin was used as additional therapy in seven patients with severe chronic congestive cardiac failure. The effect on renal function in this situation was measured. Renal function improved in four of the seven patients, and this improvement was associated with improvement in their clinical condition; in two other patients, modest improvement in renal function was not associated with symptomatic relief which may have been the result of a gain in weight.