Manual vs robotically assisted laparoscopic surgery in the performance of basic manipulation and suturing tasks

OBJECTIVE: To compare the surgical performance of manual and robotically assisted laparoscopic instruments on basic maneuvers and intracorporeal suturing in inanimate models. DESIGN: A set of laparoscopic tasks was used to evaluate basic endoscopic movements and intracorporeal suturing: positioning a cylinder on a Peg-Board, dropping beads into receptacles, running a 25-cm rope, and capping a hypodermic needle. Intracorporeal knot tying and running a suture through predetermined points were evaluated separately. The sutures used for these tasks were 2-0 and 4-0 silk and 6-0 and 7-0 polypropylene. PARTICIPANTS: Twenty surgeons completed the set of laparoscopic tasks manually and then with a robotically assisted system. None had used the robotic system before. MAIN OUTCOME MEASURES: Time required to complete the tasks and the precision in performing them. RESULTS: The robotic system accurately reproduced the movements of the surgeons and filtered their hand tremors efficiently. In the basic tasks, operative times were significantly longer for the robotic system (P<.001). In the suturing tasks, operative times were longer with the use of the robotic system for sutures sizes 2-0 and 4-0 (P<.001). However, time differences were not significant for suture sizes 6-0 and 7-0 (P> or =.07). Precision measurements were similar for all tasks using the manual instruments and the robotically assisted system. No significant differences were found between the performance of advanced laparoscopic surgeons and laparoscopic fellows. CONCLUSIONS: Laparoscopic maneuvering and suturing is faster and just as precise when performed manually as when performed with the prototype robotic system. These differences in speed are inversely proportional to the size of the suture. Future generations of the robotic system may eliminate these differences.     

Robotically assisted laparoscopic microsurgical uterine horn anastomosis

OBJECTIVE: To evaluate the feasibility, safety, and sterility issues with regard to the use of a robotic device to perform uterine horn anastomosis in a live porcine model. DESIGN: Prospective animal study. SETTING: Landrace-Yorkshire pigs in a conventional laboratory setting. INTERVENTION(S): Six female pigs underwent laparoscopic bipolar electrocoagulation of the distal uterine horns. Two weeks later, the uterine horns were reanastomosed laparoscopically with use of a robotic system for microsuturing. Necropsy was performed 4 weeks later to assess postoperative adhesions and anastomosis patency. MAIN OUTCOME MEASURE(S): Tubal patency; secondary measures were operative time, complications, and surgeon fatigue. RESULT(S): The mean (+/-SD) total operative time per animal was 170+/-34 minutes including setting up and dismantling the robotic arms. The robot functioned well with only minor technical problems. All pigs survived both surgeries with no perioperative complications related to the use of the robot. Patency was confirmed after completing each anastomosis (12 anastomoses; 100% patency). Four weeks later, necropsy showed that eight anastomoses were still patent (67%). Only one pig had bilateral occlusion. Surgeon's fatigue was mild for each animal study. CONCLUSION(S): Robotic technology can be used safely in creating laparoscopic microsurgical anastomoses. The robot functioned properly in a sterile operating room environment. Adequate patency rates were achieved during the acute phase and at 4-week follow-up. Robotic technology has the potential to make laparoscopic microsuturing easier.     

Counterdiffusion protein crystallisation in microgravity and its observation with PromISS (protein microscope for the international space station)

The crystallisation by counterdiffusion is a very efficient technique for obtaining high-quality protein crystals. A prerequisite for the use of counterdiffusion techniques is that mass transport must be controlled by diffusion alone. Sedimentation and convection can be avoided by either working in gelled systems, working in systems of small dimensions, or in the absence of gravity. We present the results from experiments performed on the ISS using the Protein Microscope for the International Space Station (PromISS), using digital holography to visualise crystal growth processes. We extensively characterised three model proteins for these experiments (cablys3*lysozyme, triose phosphate isomerase, and parvalbumin) and used these to assess the ISS as an environment for crystallisation by counterdiffusion. The possibility to visualise growth and movement of crystals in different types of experiments (capillary counterdiffusion and batch-type) is important, as movement of crystals is clearly not negligible.     

EXAFS, magnetic, spectral, and thermal studies on a new polymeric copper mixed-valence compound with the 2-thioisoorotato bridging ligand

From the reaction, in aqueous medium, of 2-thioisoorotic acid and copper carbonate, an orange compound can be isolated. The formula unit contains only one copper and one 2-tioisoorotato anion. This compound has been studied by means of extended X-ray atomic force spectroscopy (EXAFS), magnetic measurements, spectral (infrared, electronic and electron paramagnetic resonance (EPR)) and thermal methods (thermogravimetry, differential scanning calorimetry, evolved gas infrared analysis). EXAFS measurements point out the existence of a first shell around the copper atoms formed by a sulphur atom (Cu–S 0.2209 nm) and two oxygen atoms (Cu–O 0.1947 nm). This coincides with the coordination mode proposed for the ligand from infrared data. The structure may be described as a chain-like structure in which the metal ions are bridged by 2-thioisoorotato anions through both oxygen atoms of the carboxylate group and the sulphur atom, (S2)]–Cu–[(O5,O5)–2-thioisoorotato–(S2)]–Cu–[(O5,O5). Also, the weak involvement of an endocyclic nitrogen atom in the four-membered chelate formation with the sulphur atom cannot be rejected except at distances Cu–N beyond 0.23 nm. Whereas EXAFS measurements detect the only presence of Cu(I), magnetic measurements indicate there is a mixture of valence states of copper atoms (10% CuII+90% CuI). On the other hand, the compounds exhibit an axial EPR spectrum which is typical from a magnetically diluted Cu(II) compound with a stronger ligand field in the equatorial plane. Finally, in order to determine the homogeneity of this compound, we have analysed this sample by electron microscopy. It is composed of spheres with radii ranging between 1.3 and 1.7 m and cylinders whose length ranges between 6 and 10 m and width between 1.2 and 1.6 m. Energy dispersive spectroscopic analysis was performed on several points and areas of this polymer. In all analyses, the ratio Cu : S was the expected 1 : 1 without any appreciable difference between spheres and cylinders. These results seem to indicate a similar composition in both morphologies, pointing to the presence of two polymorphic phases. This could be the reason for the unsuccessful attempts to obtain single crystals of this polymer to date. © 1998 Chapman & Hall     

Chemical stabilization of porous silicon for enhanced biofunctionalization with immunoglobulin

Porous silicon (PSi) is widely used in biological experiments, owing to its biocompatibility and well-established fabrication methods that allow tailoring its surface. Nevertheless, there are some unresolved issues such as deciding whether the stabilization of PSi is necessary for its biological applications and evaluating the effects of PSi stabilization on the surface biofunctionalization with proteins. In this work we demonstrate that non-stabilized PSi is prone to detachment owing to the stress induced upon biomolecular adsorption. Biofunctionalized non-stabilized PSi loses the interference properties characteristic of a thin film, and groove-like structures resulting from a final layer collapse were observed by scanning electron microscopy. Likewise, direct PSi derivatization with 3-aminopropyl-triethoxysilane (APTS) does not stabilize PSi against immunoglobulin biofunctionalization. To overcome this problem, we developed a simple chemical process of stabilizing PSi (CoxPSi) for biological applications, which has several advantages over thermal stabilization (ToxPSi). The process consists of chemical oxidation in H₂O₂, surface derivatization with APTS and a curing step at 120 °C. This process offers integral homogeneous PSi morphology, hydrophilic surface termination (contact angle θ = 26°) and highly efficient derivatized and biofunctionalized PSi surfaces (six times more efficient than ToxPSi). All these features are highly desirable for biological applications, such as biosensing, where our results can be used for the design and optimization of the biomolecular immobilization cascade on PSi surfaces.     

The short form of the prolactin (PRL) receptor silences PRL induction of the beta-casein gene promoter

The PRL receptor (PRLR) is a member of the cytokine receptor superfamily. Rats and mice express two forms of PRLR, short (SPRLR) and long (LPRLR), which differ in the length and sequence of their cytoplasmic domains. We have analyzed the ability of each form of rat PRLR to transduce lactogenic signals in a bovine mammary gland epithelial cell line. The rat PRLR forms were expressed and detected by RT-PCR, indirect immunofluorescence, and cell surface ligand binding. When the biological activity of each form of PRLR was assessed by transient transfection, we found that the long form was able to activate the beta-casein gene promoter and that the short form was inactive. Interestingly, the coexpression of both forms of PRLR resulted in a block of PRL signal to the milk protein gene promoter as a function of the concentration of the SPRLR. Similar results were obtained when LPRLR was coexpressed with totally or partially inactive tyrosine mutants of either the Nb2 form or the LPRLR form. Thus, these results suggest that the SPRLR form has at least one clear biological function, i.e. to silence lactogenic signals and to contribute to a differential and acute PRL effect in rat tissues. Furthermore, the data derived from coexpression of LPRLR and PRLR mutants confirm a crucial role of the C-terminal tyrosine residue in lactogenic signaling and the dimerization of PRLRs.     

Banding structures in induced morphology crystal aggregates of CaCO3

Average radial growth rates in induced morphology crystal aggregates (IMCA) of CaCO₃ with sheaf-of-wheat morphologies range between 33.4 and 111 m/day. The growth process has not been found to be diffusion-controlled. Banding structures appearing in this kind of IMCA are explained just like rhythmic structures similar in origin to Liesegang rings, but the banding law in this case being modified by the matrix effect. Genetical models explaining the formation of ribbons with different particle density are also proposed.     

Nanostructured porous silicon micropatterns as a tool for substrate-conditioned cell research

ABSTRACT: The localized irradiation of Si allows a precise patterning at the microscale of nanostructured materials such as porous silicon (PS). PS patterns with precisely defined geometries can be fabricated by using ion stopping masks. The nanoscale textured micro patterns were used to explore their influence as microenviroments for human mesenchymal stem cells (hMSCs). In fact, the change of photoluminescence emission from PS upon aging in physiological solution suggests the intense formation of silanol surface groups, which may play a relevant role in ulterior cell adhesion. The experimental results show that hMSCs are sensitive to the surface micropatterns. In this regard, preliminary -catenin labeling studies reveal the formation of cell-cell interaction structures, while microtubule orientation is strongly influenced by the selective adhesion conditions. Relevantly, Ki67 assays support a proliferative state of hMSCs on such nanostructured micropatterns comparable to that of standard cell culture platforms, which reinforces the candidature of porous silicon micropatterns to become a conditioning structure for in-vitro culture of hMSCs.     

Combustion synthesis of electrical contact materials

Various electrical contact materials have been obtained by self-sustained high-temperature synthesis (SHS) followed by a hot compression step. The materials studied are TiB₂ and TiC-based cermets with a copper or aluminium metal matrix. The density, electrical conductivity, and hardness of the cermets produced in this way were measured. The microstructure of the cermets was analyzed by X-ray diffraction and optical microscopy. The conductivity and hardness of the TiB₂ cermets with 40 wt % aluminium are competitive to the properties of common silver refractory metals for contact applications. TiB₂ cermets with 40 wt % of copper possess a larger porosity which may be prevented by an increased copper content to reduce the reaction temperature.