Objective. To study the effects of osteoclasttargeted therapies, such as osteoprotegerin (OPG) and pamidronate, on joint inflammation and bone destruction using a tumor necrosis factor ␣ (TNF␣)-transgenic mouse model.Methods. Mice were placed into 5 groups that received either OPG, pamidronate, a combination of both agents, infliximab as a positive control, or phosphate buffered saline as a negative control. Treatment was initiated at the onset of arthritis, continued over 6 weeks, and thereafter, the clinical, radiologic, and histologic outcomes were assessed.Results. A significant improvement in clinical symptoms, as assessed by the reduction of paw swelling, was only found in the infliximab group, whereas all other treatment groups failed to show significant improvement. However, when assessing structural damage with radiographic analysis, a significant retardation of joint damage was evident in animals treated with OPG (55% reduction of erosions), pamidronate (50% reduction of erosions) the combination therapy of OPG and pamidronate (64% reduction of erosions), and with infliximab (66% reduction of erosions). Confirming these data, quantitative histologic analysis revealed a significant reduction in the size of bone erosions in all treatment groups (OPG 56%, pamidronate 53%, OPG and pamidronate 81%, and infliximab 46%) compared with the control group. Furthermore, a significant reduction of osteoclast numbers was seen in animals treated with OPG alone or in combination with pamidronate as well as in animals treated with infliximab.Conclusion. These data suggest that OPG alone or in combination with bisphosphonates is an effective therapeutic tool for the prevention of TNF␣-mediated destruction of bone by reducing the number of boneresorbing cells in the inflammatory tissue.

Ghrelin plasma concentrations increase during fasting and fall rapidly after nutrient ingestion. We hypothesized that insulin or glucose could regulate ghrelin secretion by a feedback mechanism. In this randomized, double-blind, placebo-controlled crossover study, three different study days were carried out in nine healthy volunteers (age 26 ؎ 6 years). On each day, stepwise increasing systemic glucose concentrations of 5.0, 8.3, and 11.1 mmol/l were attained by intravenous infusion of glucose, representing fasting and postprandial conditions. Ghrelin plasma concentration was studied during concomitant exogenous hyperinsulinemia, inhibition of endogenous insulin production by somatostatin infusion, and placebo time control, respectively. Elevated glucose concentrations increased circulating insulin to 612 ؎ 85 pmol/l (P < 0.01), but they did not affect ghrelin concentrations. Prolonged hyperinsulinemia by exogenous infusion resulted in circulating insulin of 1,602 ؎ 261 pmol/l (P < 0.01) and suppressed plasma ghrelin to 49.6% of baseline (P < 0.01). During administration of somatostatin, insulin concentration remained constant, but an even greater decrease in ghrelin to 39.5% of baseline was noted (P < 0.01). Hyperglycemia does not decrease ghrelin, and a reduction in ghrelin is only seen at supraphysiological insulin concentrations. In contrast, systemic ghrelin concentrations are decreased by somatostatin. The meal-related suppression of ghrelin appears not directly regulated by glucose or insulin.

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Amylin is a 37-amino acid pancreatic polypeptide, probably involved in the pathophysiology of Type 2 (non-insulin-dependent) diabetes mellitus. We have determined amylin in human plasma by extraction-based radioimmunoassay (Sep-Pak C18). Of 23 healthy control subjects plasma amylin was determined as 11.9 +/- 3.5 ng/l. Of 27 patients with Type 2 diabetes receiving insulin the amylin levels were lower, and in 16 patients with Type 2 diabetes on oral medication they were higher than in the control subjects; 8.2 +/- 4.4 ng/l (p less than 0.01) vs 18.8 +/- 9.9 ng/l (p less than 0.05). In 14 Type 1 (insulin-dependent) diabetic patients we found extremely low mean amounts of amylin: 2.9 +/- 1.9 ng/l (p less than 0.002). Thus, basal amylin appears to be associated with the capacity to release insulin. An oral glucose load stimulated the release of amylin, this was more pronounced in patients with Type 2 diabetes than in healthy subjects. An excellent correlation of mean amylin with mean insulin concentrations was obtained (r = 0.949). In patients with Type 2 diabetes amylin was reduced congruent to decreases in C-peptide during a hyperinsulinaemic, euglycaemic glucose clamp experiment (r = 0.971 for linear correlation between C-peptide levels and amylin). We conclude, that amylin and insulin are co-secreted in humans, and that the amylin release is under feedback-control by insulin.

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