The role of microstructured and interconnected pore channels in a collagen-based nerve guide on axonal regeneration in peripheral nerves.

The use of bioengineered nerve guides as alternatives for autologous nerve transplantation (ANT) is a promising strategy for the repair of peripheral nerve defects. In the present investigation, we present a collagen-based micro-structured nerve guide (Perimaix) for the repair of 2 cm rat sciatic nerve defects. Perimaix is an open-porous biodegradable nerve guide containing continuous, longitudinally orientated channels for orientated nerve growth. The effects of these nerve guides on axon regeneration by six weeks after implantation have been compared with those of ANT. Investigation of the regenerated sciatic nerve indicated that Perimaix strongly supported directed axon regeneration. When seeded with cultivated rat Schwann cells (SC), the Perimaix nerve guide was found to be almost as supportive of axon regeneration as ANT. The use of SC from transgenic green-fluorescent-protein (GFP) rats allowed us to detect the viability of donor SC at 1 week and 6 weeks after transplantation. The GFP-positive SC were aligned in a columnar fashion within the longitudinally orientated micro-channels. This cellular arrangement was not only observed prior to implantation, but also at one week and 6 weeks after implantation. It may be concluded that Perimaix nerve guides hold great promise for the repair of peripheral nerve defects.

Effect of carbohydrate- and protein-rich meals on exercise-induced activation of lipolysis in obese subjects.

Exercise is an important part of obesity treatment concepts to support fat mobilisation from adipose tissue and also fat oxidation nolich is impaired in obese subjects. In normal weight subjects it is well known that stimulation of plasma insulin levels by a carbohydrate meal can inhibit lipolysis and subsequent fat oxidation. Since obese subjects frequently have elevated basal and postprandial insulin levels the effect of carbohydrate- and protein-rich test meals on exercise-induced activation of lipolysis is of special interest. Twenty obese subjects performed bicycle exercise for 30 min in the fasted state, 30 min after a carbohydrate-or a protein-rich meal, and 120 min after the carbohydrate meal (n=12), respectively, at low intensity. Activation of lipolysis was assessed by plasma glycerol levels. In addition, plasma insulin, glucose, and lactate concentrations were determined. In comparison to the fasted state, the carbohydrate meal suppressed activation of lipolysis. Following the protein meal, exercise led to an attenuated but significant increase of glycerol levels. A similar rise was observed when the carbohydrate meal was ingested 2 h prior to the exercise bout. To improve exercise-induced lipolysis and subsequent fat oxidation during low-intensity exercise obese subjects should not ingest carbohydrates immediately before exercise. Hunger sensations should be satisfied with protein-rich food. When carbohydrates are consumed 2 h prior to exercise its lipolytic effect is comparable to the protein meal. These data are useful in every day dietary counselling and might help to improve weight loss during obesity treatment.

Relation of plasma obestatin levels to bmi, gender, age and insulin.

Obestatin is supposed to be involved in nutrient homeostasis. Therefore, basal plasma obestatin levels were investigated in 321 normal weight and obese subjects in relation to body mass index, gender, age, insulin concentrations, and type 2 diabetes mellitus. Additionally, postprandial obestatin levels were determined in 20 normal weight subjects. Basal obestatin levels in females were higher compared to males (193.6+/-5.8 vs. 140.6+/-5.1 pg/ml). Obestatin levels correlated inversely and significantly with body mass index (f: r=-0.632, p<0.001; m: r=-0.487, p<0.001) and basal insulin levels (f: r=-0.536, p<0.001; m: r=-0.320, p=0.008) in females and males. However, in a multiple regression analysis as well as in a matched comparison of a low and high insulin group no significant relationship between insulin and obestatin levels was observed in nondiabetics. On the other hand, inclusion of type 2 diabetics with higher insulin levels resulted in a significant inverse correlation. Obestatin levels were independent of age in both sexes. In patients with type 2 diabetes mellitus basal obestatin levels were not different compared to nondiabetic subjects when matched for gender, body mass index, and insulin. In normal weight subjects, postprandial obestatin levels showed a significant decrease between 60 and 90 minutes rising to basal levels thereafter. The present data demonstrate a relation of plasma obestatin levels to body weight, gender and food intake, but not to age. The inverse relationship with insulin might depend on the level of hyperinsulinemia. The present data are compatible with a potential role of obestatin in nutrient regulation.