Safety, tolerability, pharmacokinetics and pharmacodynamics of AZP-531, a first-in-class analogue of unacylated ghrelin, in healthy and overweight/obese subjects and subjects with type 2 diabetes.

AIM: To explore the safety, pharmacokinetics and pharmacodynamics in humans of the unacylated ghrelin analogue AZP-531, designed to improve glycaemic control and reduce weight. METHODS: Assessments, including glucose measurements, were performed in a three-part randomized study. In Part A, healthy subjects [n = 44, age 18-50 years, body mass index (BMI) 20-28 kg/m(2) ] received a single subcutaneous dose of 0.3, 3, 15, 30, 60 or 120 µg/kg AZP-531 or placebo. In Part B, overweight/obese subjects (n = 32, age 18-65 years, BMI 28-38 kg/m(2) ) and in Part C, patients with type 2 diabetes [T2D; n = 36, age 18-65 years, BMI 20-40 kg/m(2) , glycated haemoglobin (HbA1c) 7-10%] received AZP-531 or placebo for 14 days (daily doses of 3, 15, 30 or 60 µg/kg and 15, 2 × 30 or 60 µg/kg, respectively). RESULTS: AZP-531 was well tolerated. Single- and multiple-dose pharmokinetic variables were similar. Maximum AZP-531 concentrations were typically reached at 1 h post-dose. Observed maximum concentration (Cmax ) and area under the curve were dose-proportional. The mean terminal half-life (t1/2 ) was 2-3 h. In Part B, AZP-531 doses of ≥15 µg/kg significantly improved glucose concentrations, without increasing insulin levels, suggesting an insulin-sensitizing effect. AZP-531 decreased mean body weight by 2.6 kg (vs 0.8 kg for placebo). In Part C, glucose variables improved in all groups, including placebo, suggesting a study effect in uncontrolled patients at baseline. Notwithstanding, AZP-531 60 µg/kg reduced HbA1c by 0.4% (vs 0.2% for placebo) and body weight by 2.1 kg (vs 1.3 kg for placebo). CONCLUSIONS: AZP-531 was well tolerated in this first-in-human study. Its pharmacokinetic profile, suitable for once-daily dosing, and metabolic effects support further clinical development for T2D.

Elevated ratio of acylated to unacylated ghrelin in children and young adults with Prader-Willi syndrome.

Prader-Willi syndrome (PWS) is characterized by a switch from failure to thrive to excessive weight gain and hyperphagia in early childhood. Hyperghrelinemia may be involved in the underlying mechanisms of the switch. The purpose of this study is to evaluate acylated ghrelin (AG) and unacylated ghrelin (UAG) levels in PWS and investigate their associations with hyperphagia. This is a cross-sectional clinical study conducted in three PWS expert centers in the Netherlands and France. Levels of AG and UAG and the AG/UAG ratio were determined in 138 patients with PWS (0.2-29.4 years) and compared with 50 age-matched obese subjects (4.3-16.9 years) and 39 healthy controls (0.8-28.6 years). AEBSF was used to inhibit deacylation of AG. As a group, PWS patients had higher AG but similar UAG levels as healthy controls (AG 129.1 vs 82.4 pg/ml, p = 0.016; UAG 135.3 vs 157.3 pg/ml, resp.), resulting in a significantly higher AG/UAG ratio (1.00 vs 0.61, p = 0.001, resp.). Obese subjects had significantly lower AG and UAG levels than PWS and controls (40.3 and 35.3 pg/ml, resp.), but also a high AG/UAG ratio (1.16). The reason for the higher AG/UAG ratio in PWS and obese was, however, completely different, as PWS had a high AG and obese a very low UAG. PWS patients without weight gain or hyperphagia had a similar AG/UAG ratio as age-matched controls, in contrast to those with weight gain and/or hyperphagia who had an elevated AG/UAG ratio. The switch to excessive weight gain in PWS seems to coincide with an increase in the AG/UAG ratio, even prior to the start of hyperphagia.

Comparison of UVA protection afforded by high sun protection factor sunscreens.

UVA protection afforded by 6 different sunscreens with a sun protection factor of 21 or more was compared by means of the persistent pigmentation darkening method. Colorimetric and visual assessment showed significant differences in UV radiation-induced pigmentation at 2 hours. The labeled sun protection factor of the tested sunscreens was not predictive of UVA protection level.

Healing of experimental aneurysms. II: Platelet extracts can increase the thickness of the neointima at the neck of treated aneurysms.

PURPOSE: To assess the effect of platelet extracts (PE) on neointima formation following gelfoam packing of experimental porcine aneurysms. A strategy involving the local delivery of platelet growth factors may potentially improve long term results of endovascular treatment of aneurysms. METHODS: Bilateral lateral wall common carotid aneurysms were constructed on 30 pigs. A collagen sponge containing a PE rich in growth factors was used to pack one aneurysm with the controlateral lesion being embolized with a sponge containing NaCl 0.9% (22 animals). In 8 animals, a control sponge was used on both sides. Animals were sacrificed at 1, 2, 3, 4 and 9 weeks and the thickness of the neointima covering the neck of PE-treated aneurysms was measured in 5 locations for each lesion at 2 and 3 weeks and compared with the control aneurysm of the same animal. Morphometric data was analysed using the paired Student's t-test. RESULTS: The thickness of the neointima was significantly increased in lesions treated with PE as compared to control lesions at 2 weeks (p = 0.008, n = 9). There was no significant difference at 3 weeks (p = 0.99, n = 9). There was no significant difference between lesions of control animals (p = 0.95, n = 8). CONCLUSION: PE rich in growth factors can increase the thickness of the neointima at the neck of treated experimental porcine aneurysms at 2 weeks, but had no effect at 3 weeks. This accelerated neointimal formation may have some value in improving healing following endovascular treatment. This hypothesis could not be supported with this experimental model which has a spontaneous tendency to heal. Further studies using an animal model which reproduces the clinical problem of recurrences may help to define the role of the local delivery of growth factors in combination with coils in a strategy designed to improve results of endovascular treatment.

Healing mechanisms in experimental aneurysms. I. Vascular smooth muscle cells and neointima formation.

PURPOSE: The purpose of this work is to better define healing phenomena in this model, in an effort to find strategies to improve long term results of endovascular treatment. METHODS: Lateral wall venous pouch aneurysms were constructed on both carotid arteries in 30 pigs. The aneurysms were packed with collagen sponges per-operatively in 25 animals. Angiography, serial histological studies and immuno-histochemistry tests were used to study healing phenomena and measure neointima formation at various time intervals from 1 day to 9 weeks after surgery. GDC embolization was performed in 5 other pigs for comparison with the collagen sponge model. Explants from the neointima at the neck of aneurysms as well as from the parent artery of 8 pigs were prepared in an attempt to grow and to characterize in vitro cells responsible for healing porcine aneurysms using immunocytochemistry and enzymatic assays. To confirm the hypothesis that an analogy exists between cells involved in aneurysmal healing and neointimal cells found in restenosis, explant outgrowths were scored and compared to explants from intact carotid arteries and carotid arteries subjected to angioplasty in 3 other animals. In addition, to test the value of neointima measurements in quantifying results, 6 dogs were analysed to correlate the thickness of the neointima formed at the neck of aneurysms with angiographic results in animals prone to recurrences. RESULTS: Histopathological findings with collagen sponge packing were similar to the ones following coil embolization. Porcine aneurysms had a strong tendency to heal with a thick neointima primarily composed of vascular smooth muscle cells (VSMCs). Aneurysms in dogs did not heal as well and the neointima at the neck of treated lesions was thin. Cells responsible for healing of experimental porcine aneurysms could be cultured in vitro, and are activated VSMCs. These cells, similar to those harvested following balloon injury, had a higher colony forming capacity and an accelerated explant outgrowth rate as compared to cells derived from the parent artery. CONCLUSION: Animals which heal poorly harbor a thin or deficient neointima at the neck of treated aneurysms. Favorable healing in porcine aneurysms involves VSMCs which form a thick neointima. These VSMCs can be cultured in vitro. They share similar outgrowth characteristics with VSMCs recovered after balloon angioplasty. The collagen sponge model may be useful to harvest cells for in vitro experimentation and in the in vivo evaluation of the local delivery of potential therapeutic molecules thought to improve healing following embolization of aneurysms.