Characterizing the learning curve of the VBLaST-PT© (Virtual Basic Laparoscopic Skill Trainer)

Background

Mastering laparoscopic surgical skills requires considerable time and effort. The Virtual Basic Laparoscopic Skill Trainer (VBLaST-PT^©) is being developed as a computerized version of the peg transfer task of the Fundamentals of Laparoscopic Surgery (FLS) system using virtual reality technology. We assessed the learning curve of trainees on the VBLaST-PT^© using the cumulative summation (CUSUM) method and compared them with those on the FLS to establish convergent validity for the VBLaST-PT^©.

Methods

Eighteen medical students from were assigned randomly to one of three groups: control, VBLaST-training, and FLS-training. The VBLaST and the FLS groups performed a total of 150 trials of the peg-transfer task over a 3-week period, 5 days a week. Their CUSUM scores were computed based on predefined performance criteria (junior, intermediate, and senior levels).

Results

Of the six subjects in the VBLaST-training group, five achieved at least the “junior” level, three achieved the “intermediate” level, and one achieved the “senior” level of performance criterion by the end of the 150 trials. In comparison, for the FLS group, three students achieved the “senior” criterion and all six students achieved the “intermediate” and “junior” criteria by the 150th trials. Both the VBLaST-PT^© and the FLS systems showed significant skill improvement and retention, albeit with system specificity as measured by transfer of learning in the retention test: The VBLaST-trained group performed better on the VBLaST-PT^© than on FLS (p = 0.003), whereas the FLS-trained group performed better on the FLS than on VBLaST-PT^© (p = 0.002).

Conclusions

We characterized the learning curve for a virtual peg transfer task on the VBLaST-PT^© and compared it with the FLS using CUSUM analysis. Subjects in both training groups showed significant improvement in skill performance, but the transfer of training between systems was not significant.     

The effect of cyclic mechanical strain on the expression of adhesion-related genes by periodontal ligament cells in two-dimensional culture

Saminathan A, Vinoth KJ, Wescott DC, Pinkerton MN, Milne TJ, Cao T, Meikle MC. The effect of cyclic mechanical strain on the expression of adhesion‐related genes by periodontal ligament cells in two‐dimensional culture. J Periodont Res 2012; 47: 212–221. © 2011 John Wiley & Sons A/S Background and Objective: Cell adhesion plays important roles in maintaining the structural integrity of connective tissues and sensing changes in the biomechanical environment of cells. The objective of the present investigation was to extend our understanding of the effect of cyclic mechanical strain on the expression of adhesion‐related genes by human periodontal ligament cells. Material and Methods: Cultured periodontal ligament cells were subjected to a cyclic in‐plane tensile deformation of 12% for 5 s (0.2 Hz) every 90 s for 6–24 h in a Flexercell FX‐4000 Strain Unit. The following parameters were measured: (i) cell viability by the MTT assay; (ii) caspase‐3 and ‐7 activity; and (iii) the expression of 84 genes encoding adhesion‐related molecules using real‐time RT‐PCR microarrays. Results: Mechanical stress reduced the metabolic activity of deformed cells at 6 h, and caspase‐3 and ‐7 activity at 6 and 12 h. Seventy‐three genes were detected at critical threshold values < 35. Fifteen showed a significant change in relative expression: five cell adhesion molecules (ICAM1, ITGA3, ITGA6, ITGA8 and NCAM1), three collagen α‐chains (COL6A1, COL8A1 and COL11A1), four MMPs (ADAMTS1, MMP8, MMP11 and MMP15), plus CTGF, SPP1 and VTN. Four genes were upregulated (ADAMTS1, CTGF, ICAM1 and SPP1) and 11 downregulated, with the range extending from a 1.76‐fold induction of SPP1 at 12 h to a 2.49‐fold downregulation of COL11A1 at 24 h. Conclusion: The study has identified several mechanoresponsive adhesion‐related genes, and shown that onset of mechanical stress was followed by a transient reduction in overall cellular activity, including the expression of two apoptosis ‘executioner’ caspases.     

A ZnO@ABS/TPU/CaSiO3 3D skeleton and its adsorption/photocatalysis properties for dye contaminant removal

Both adsorption and photocatalysis are considered to be effective methods for removing organic contaminants from dye wastewater. In this study, the construction of 3D skeletons based on the nanoparticles ZnO and ABS/TPU/calcium silicate (CaSiO₃) (shortened as ATC) were fabricated via fused deposition molding (FDM) technology. Characterization by scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) depicted that ZnO nanospheres had been successfully grown on the 3D skeleton surface with an enlarged specific surface area. As the results of the RhB adsorption and photocatalytic degradation experiments showed, the removal ratio of RhB onto the ZnO-ATC skeleton was as high as 97.94% and the synergistic effect of adsorption and photocatalysis greatly shortened the RhB degradation time under ultraviolet light irradiation. The nanocomposites synthesized in this study showed a significant removal ability for organic pollutants, and could effectively overcome the limitation of the secondary removal of photocatalysts.

Enhanced synergistic effect of photocatalytic and adsorption was realized through the system constructed of ZnO nanoparticle loaded 3D skeleton.     

Thiolated poly(aspartic acid)-functionalized two-dimensional MoS2, chitosan and bismuth film as a sensor platform for cadmium ion detection

In this work, a sensitive electrochemical platform for determination of cadmium ions (Cd²⁺) is obtained using thiolated poly(aspartic acid) (TPA)-functionalized MoS₂ as a sensor platform by differential pulse anodic stripping voltammetry (DPASV). The performance of the TPA–MoS₂-modified sensor is systemically studied. It demonstrates that the TPA–MoS₂ nanocomposite modified sensor exhibits superior analytical performance for Cd²⁺ over a linear range from 0.5 μg L⁻¹ to 50 μg L⁻¹, with a detection limit of 0.17 μg L⁻¹. Chitosan is able to form a continuous coating film on the surface of the GC electrode. The good sensing performance of the TPA–MoS₂-modified sensor may be attributed to the following factors: the large surface area of MoS₂ (603 m² g⁻¹), and the abundant thiol groups of TPA. Thus, the TPA–MoS₂-modified sensor proves to be a reliable and environmentally friendly tool for the effective monitoring of Cd²⁺ existing in aquacultural environments.

In this work, a sensitive electrochemical platform for determination of cadmium ions (Cd²⁺) is obtained using thiolated poly(aspartic acid) (TPA)-functionalized MoS₂ as a sensor platform by differential pulse anodic stripping voltammetry (DPASV).     

Synthesis of stable-isotope-labeled N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide and N-(3-dimethylaminopropyl)-N′-ethylurea

N-(3-Dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) is a carbodiimide coupling reagent commonly used for the preparation of amides from carboxylic acids and amines. Because of initial concerns regarding the genotoxicity of EDC and its use in GMP syntheses at Bristol Myers Squibb, the quantitation of residual EDC and its by-product N-(3-dimethylaminopropyl)-N′-ethylurea (EDU) by liquid chromatography–mass spectrometry (LCMS) impurity analysis was required. These analyses required the use of stable-isotope-labeled EDC and EDU to serve as internal standards. To meet this need, stable-isotope-labeled EDC 9 and EDU 10 were prepared from [1,2-¹³C₂] ethylene glycol and [¹³C,¹⁵N] potassium cyanide in overall yields of 6% and 8%, respectively.