Changes in oxidative stress in response to different levels of energy restriction in obese ponies.

The present study evaluated the effect of different levels of energy restriction on metabolic parameters in obese ponies. Relative weight changes, markers of lipid metabolism and oxidant/antioxidant balance were monitored. A total of eighteen obese (body condition score ≥ 7/9) Shetland ponies were studied over a 23·5-week trial, which was divided into three periods. The first period involved a 4-week adaptation period in which each animal was fed 100% of their maintenance energy requirements needed to maintain a stable obese body weight (MERob). This was followed by a 16·5-week weight-loss period in which ponies were assigned to receive either 100% (control group, CONTROL), 80% (slow weight-loss (SLOW) group) or 60% (rapid weight-loss (RAPID) group) of their MERob. During the 3-week end-phase period, all ponies were again fed 100% of their MERob. Relative weight loss was higher in the RAPID group (P< 0·001) compared with the SLOW group. No linear relationship was found as a doubling of the percentage of energy restriction was accompanied by a tripling of the percentage of weight loss. Relative weight gain afterwards in the end-phase period was higher in the RAPID group (P< 0·001) compared with the SLOW and CONTROL groups. During the weight-loss period, TAG and NEFA concentrations were highest in the RAPID group, as were α-tocopherol and ferric-reducing ability of plasma concentrations. After 8 weeks of weight loss, the concentrations of advanced oxidation protein products were higher in the RAPID group compared with the SLOW and CONTROL groups (P< 0·001). In conclusion, the level of energy restriction influences the extent of changes in oxidant/antioxidant balance. Practically, more severe energy restriction regimens may be associated with a greater regain of weight after the restriction period.

A non-hydrocephalic goat experimental model to evaluate a ventriculosinus shunt.

The ventriculosinus shunt is a promising treatment for hydrocephalus. Currently, different shunt techniques exist, and it is not clear whether one is preferable. This pilot study reports on a non-hydrocephalic goat model (Saanen breed) that provides opportunities to evaluate and optimize several aspects of the ventriculosinus shunt technique. Analysis of the coagulation properties of 14 goats by a viscoelastic coagulation monitor showed that goats have a hypercoagulable state compared to humans. This property can be partially counteracted by antiplatelet drugs. During implantation of a ventriculosinus shunt, a pulsatile reflux of blood was observed. After implantation, the animals recovered to their preoperative state, and none of them developed a superior sagittal sinus thrombosis. Evaluation of the shunts after 16 days showed an obstructing luminal clot. Several model-related factors may have promoted this obstruction: the absence of hydrocephalus, the hypercoagulability of caprine blood and the smaller dimensions of the caprine superior sagittal sinus. However, the pulsatile reflux of blood, which is caused by the compliance of the shunt system distal to the valve, may have been an important factor as well. In conclusion, the non-hydrocephalic goat model limits animal suffering and simplifies the study protocol. This model allows researchers to evaluate their implantation technique and shunt hardware but not the efficacy of the treatment or shunt survival.

Intussusceptive angiogenesis and expression of Tie receptors during porcine metanephric kidney development.

Intussusceptive angiogenesis (IA) is required for normal embryonic vascular development. The Tie family of receptors and their ligands, the angiopoietins, play an important role in the growth or regression of blood vessels which are important not only during development but also throughout an organism's life. The presence of IA was investigated in glomerular capillaries of the fetal porcine metanephros using Mercox II resin casts. The first signs of IA were observed in stage III glomeruli. Stage IV and V glomeruli showed numerous signs of aligned pillar formation and their successive merging to delineate the vascular entities. Furthermore, immunohistochemistry was used to determine the exact locations of the Tie receptors in the developing porcine metanephric kidneys. Tie1 and Tie2 were found in endothelial cells of all glomeruli. Strong expression of the receptors was found in podocytes of stage V glomeruli whereas a weaker expression was observed in the cuboidal epithelial cells of stage III and IV glomeruli. Remarkably, the receptors were also found in the parietal epithelium of Bowman's capsule. These findings indicate that there might be an association between the Tie receptors and the IA during porcine metanephric development and during glomerulogenesis in particular.