Testing Distinct Three-Dimensional Effects in Laparoscopy: A Prospective Randomized Trial Using the Lübecker Toolbox Curriculum.

BACKGROUND: The use of stereoscopic laparoscopic systems in minimally invasive surgery (MIS) allows a three-dimensional (3D) view of the surgical field, which improves hand-eye coordination. Depending on the stereo base used in the construction of the endoscopes, 3D systems may differ regarding the 3D effect. Our aim was to investigate the influence of different stereo bases on the 3D effect. METHODS: This was a prospective randomized study involving 42 MIS-inexperienced study participants. We evaluated two laparoscopic 3D systems with stereo bases of 2.5 mm (system A) and 3.8 mm (system B) for differences in learning MIS skills using the Lübeck Toolbox (LTB) video box trainer. We evaluated participants' performance regarding the times and repetitions required to reach each exercise's goal. After completing the final exercise ("suturing"), participants performed the exercise again using a two-dimensional (2D) representation. Additionally, we retrospectively compared our study results with a preliminary study from participants completing the LTB curriculum with a 2D system. RESULTS: The median number of repetitions until reaching the goals for LTB exercises 1, 2, 3, and 6 for system A were: 18 (range 7-53), 24 (range 8-46), 24 (range 13-51), and 21 (range 10-46), respectively, and for system B were: 12 (range 2-30), 16 (range 6-43), 17 (range 4-47), and 15 (range 6-29), respectively (p = not significant). Changing from a 3D to a 2D representation after completing the learning curve led to a longer average time required, from 95.22 to 119.3 s (p < 0.0001), for the last exercise (exercise 6; "suturing"). When comparing the results retrospectively with the learning curves acquired with the 2D system, there was a significant reduction in the number of repetitions required to reach the LTB exercise goals for exercises 1, 3, and 6 using the 3D system. CONCLUSION: Stereo bases of 2.5 and 3.8 mm provide acceptable bases for designing 3D systems. Additionally, our results indicated that MIS basic skills can be learned quicker using a 3D system versus a 2D system, and that when the 3D effect is eliminated, the corresponding compensatory mechanisms must be relearned.

O-phospho-L-serine: a modulator of bone healing in calcium-phosphate cements.

Bone substitution materials are seen as an alternative to autogenous bone transplants in the reconstruction of human bone structures. The aim of the present animal study was to evaluate the clinical handling and the conditions of bone healing after the application of a phosphoserine and collagen-I-modified calcium-phosphate cement (Biozement D). The application of phosphoserine is supposed to influence the texture of the extracellular matrix. Standardised bone defects were created in the lower jaw of 10 adult minipigs. These defects were reconstructed with a pasty calcium-phosphate cement mixture. After a healing time of 4 months, the animals were sacrificed. The mandibles of all animals were resected and non-decalcified histological sections of the areas of interest were prepared. The experiment was evaluated by means of qualitative histology and histomorphometry. The hydroxyapatite cement entirely hardened intraoperatively. Modelling and handling of the cement was facile and the margin fit to the host bone was excellent. Histology showed that resorption started in the periphery and proceeded exceptionally fast. The bony substitution, especially in phosphoserine-endowed cements, was very promising. After a healing period of 4 months, phosphoserine cements showed a bone regeneration of nearly two-thirds of the defect sizes. In the applied animal experiment, the newly developed hydroxyapatite collagen-I cement is well suited for bone substitution due to its easy handling, its excellent integration and good resorption characteristics. The addition of phosphoserine is very promising in terms of influencing resorption features and bone regeneration.

Glutamate uptake and release by astrocytes are enhanced by Clostridium botulinum C3 protein.

Inhibition of Rho activity by Clostridium botulinum C3 transferase (C3bot) versatily changes functional properties of neural cells. Using cultivated mouse astrocytes, we show here that C3bot increases both uptake and secretion of glutamate. The enhanced glutamate uptake is initiated by an NFkappaB-dependent up-regulation of the glial glutamate transporter 1 that is efficaciously sorted to the plasma membrane. The increase in cytosolic glutamate concentration promotes vesicular glutamate storage in astrocytes treated with C3bot. Parallel to the increased storage, C3-induced impairment of Rho-dependent pathways strongly enhances Ca(2+)-dependent secretion of glutamate. This is accompanied by higher levels of the SNARE protein synaptobrevin. Synaptobrevin inactivation by botulinum neurotoxin D almost completely inhibits Ca(2+)-dependent glutamate secretion triggered by C3bot, indicating that the enhanced release of glutamate mainly originates from exocytosis. In addition, C3bot increases the exocytosis/endocytosis turnover, as analyzed by the stimulated accumulation of the fluorescent dye AM1-43. The release of glutamine, the main metabolite of glutamate, is only moderately affected by C3bot. In conclusion, inhibition of Rho-dependent pathways shifts astrocytes to a secretory active stage in which they may modulate neuronal excitability.