Sustained Calcium(II)-Release to Impart Bioactivity in Hybrid Glass Scaffolds for Bone Tissue Engineering

In this study, we integrated different calcium sources into sol-gel hybrid glass scaffolds with the aim of producing implants with long-lasting calcium release while maintaining mechanical strength of the implant. Calcium(II)-release was used to introduce bioactivity to the material and eventually support implant integration into a bone tissue defect. Tetraethyl orthosilicate (TEOS) derived silica sols were cross-linked with an ethoxysilylated 4-armed macromer, pentaerythritol ethoxylate and processed into macroporous scaffolds with defined pore structure by indirect rapid prototyping. Triethyl phosphate (TEP) was shown to function as silica sol solvent. In a first approach, we investigated the integration of 1 to 10% CaCl2 in order to test the hypothesis that small CaCl2 amounts can be physically entrapped and slowly released from hybrid glass scaffolds. With 5 and 10% CaCl2 we observed an extensive burst release, whereas slightly improved release profiles were found for lower Calcium(II) contents. In contrast, introduction of melt-derived bioactive 45S5 glass microparticles (BG-MP) into the hybrid glass scaffolds as another Calcium(II) source led to an approximately linear release of Calcium(II) in Tris(hydroxymethyl)aminomethane (TRIS) buffer over 12 weeks. pH increase caused by BG-MP could be controlled by their amount integrated into the scaffolds. Compression strength remained unchanged compared to scaffolds without BG-MP. In cell culture medium as well as in simulated body fluid, we observed a rapid formation of a carbonated hydroxyapatite layer on BG-MP containing scaffolds. However, this mineral layer consumed the released Calcium(II) ions and prevented an additional increase in Calcium(II) concentration in the cell culture medium. Cell culture studies on the different scaffolds with osteoblast-like SaOS-2 cells as well as bone marrow derived mesenchymal stem cells (hMSC) did not show any advantages concerning osteogenic differentiation due to the integration of BG-MP into the scaffolds. Nonetheless, via the formation of a hydroxyapatite layer and the ability to control the pH increase, we speculate that implant integration in vivo and bone regeneration may benefit from this concept.

[Value of one-stage surgical treatment of diffuse peritonitis (relaparotomy on demand): a single-center analysis]

BACKGROUND

Despite modern surgical and intensive-care concepts, diffuse peritonitis remains a major source of high morbidity and mortality. The aim of this study was to critically evaluate the value of relaparotomy on demand (ROD) for patients with diffuse peritonitis.

PATIENTS AND RESULTS

In a retrospective analysis, the clinical course of 231 patients with diffuse peritonitis was analysed. The mean Mannheim Peritonitis Index (MPI) was 25.3. Overall lethality in this cohort was 14.3 %. In 214 patients, source control was successful during the index operation, and these patients were treated according to an on-demand strategy. For 178 of these patients, there was no demand for a relaparotomy, whereas 36 of these patients required further surgical interventions. Lethality for these subgroups was 9 % (no relaparotomy) and 27 % (relaparotomy), respectively.

CONCLUSIONS

This retrospective analysis confirms that an on-demand strategy is reasonable and feasible after successful source control and lavage. However, it still remains of clinical importance to identify parameters that may assist in selecting those patients who require a relaparotomy.

Urodilatin (INN:ularitide) as a new drug for the therapy of acute renal failure following cardiac surgery

1. Acute renal failure is a severe complication following major cardiac surgery. 2. The effects of urodilatin were evaluated in a randomized, double-blind trial in patients suffering from incipient acute renal failure following cardiac surgery. 3. In the urodilatin group (n = 7) acute renal failure was reverted, whereas in the placebo group (n = 7) six patients had to be haemofiltered or haemodialysed (P < 0.005). 4. Urodilatin induced a rapid onset of diuresis in contrast to placebo-treated patients, who remained oliguric. 5. In the placebo group four of seven patients died while still on haemodialysis (mortality rate 57.1%) during a postoperative follow-up period of 60 days, while all patients treated with urodilatin survived. 6. On the basis of these results it would appear that urodilatin is an effective drug for the treatment of incipient oliguric acute renal failure following cardiac surgery and for avoiding haemodialysis/haemofiltration.

[Technical aspects of segment I resection of the liver]

Due to posterior location and the close relationship to vascular and biliary structures, resection of tumors within the caudate lobe of the liver may be a surgical challenge as well as an oncological hazard. Various approaches and techniques of isolated tumorectomy and combined liver resections are available and must be tailored to the individual situation. Prerequisite for a low operative risk is control of bleeding which can be achieved by sequential inflow and outflow occlusion of the liver.