Robotic surgery using Senhance® robotic platform: single center experience with first 100 cases

Journal of Robotic Surgery - Until recently, robotic surgery has been associated only with the da Vinci robotic system. A novel Senhance® robotic system (TransEnterix Surgical Inc.,...     

Experimental acute pancreatitis induces mitochondrial dysfunction in rat pancreas,kidney and lungs but not in liver

Background/aimsExcessive systemic inflammatory response syndrome during severe acute pancreatitis (AP) leads to multiple organ dysfunction syndrome, which is the main cause of death and may be associated with primary mitochondrial disturbances. The aim of our study was to evaluate the role of mitochondria during experimental AP in pancreas and vital organs like kidney, lungs and liver within the first 48 h.MethodsAP was induced in 39 male Wistar rats by intraductal application of sodium taurocholate (5%, 1.75 ml/kg). Animals were divided into groups reflecting the time from induction of the AP till collection of tissues (control and 1, 3, 6, 12, 24, 48 h). Mitochondria were isolated by differential centrifugation and mitochondrial respiration rates were measured oxygraphically.Results(1) Mitochondria in pancreas are affected within the first 6 h after onset of AP, (2) kidney mitochondria are affected 24 h after onset of AP, (3) lungs mitochondria are affected within 48 h after onset of AP whereas (4) liver mitochondria remain well preserved within the first 48 h. Severe AP–induced decrease in the oxidative phosphorylation of pancreas, kidney and lungs mitochondria was more pronounced with Complex I-linked (glutamate/malate) than with Complex II-linked (succinate) substrates and was associated with inhibition of Complex I.ConclusionOur data show that the disturbances of mitochondrial energy metabolism in pancreas, kidney and lungs may play an important role in the development and progression of AP as a systemic disease.     

Effect of Laser Processing Parameters on Microstructure,Hardness and Tribology of NiCrCoFeCBSi/WC Coatings

In the present study, pulsed laser post-processing was applied to improve the properties of the thermally sprayed NiCrCoFeCBSi/40 wt.% WC coatings. The powder mix was deposited onto a mild steel substrate by flame spray method and then the as-sprayed coatings were processed by Nd:YAG laser. The peak power density applied was between 4.00 × 10⁶ and 5.71 × 10⁶ W/cm², and the laser operating speed ranged between 100 and 400 mm/min, providing processing in a melting mode. Scanning electron microscopy, energy dispersive spectroscopy, Knop hardness measurements, and “ball-on-disc” dry friction tests were applied to study the effect of the processing parameters on the geometry of laser pass and microstructure, hardness, and tribology of the processed layers. The results obtained revealed that pulsed laser processing provides a monolithic remelted coating layer with the microstructure of ultrafine, W-rich dendrites in Ni-based matrix, where size and distribution of W-rich dendrites periodically vary across remelted layer depth. The composition of W-rich dendrites can be attributed to a carbide of type (W, Cr, Ni, Fe)C. The cracks sensitivity of coatings was visibly reduced with the reduction of power density applied. The hardness of coatings was between ~1070 and ~1140 HK0.2 and correlated with microstructure size, being dependent on the processing parameters. The friction coefficient and wear rate of coatings during dry sliding were reduced by up to ~30% and up to ~2.4 times, respectively, after laser processing.     

αL β2 integrin is indispensable for CD8+ T-cell recruitment in experimental pancreatic and hepatocellular cancer

Recruitment of activated leukocytes from peripheral blood into the tumor tissue is a crucial step of the immune response, which is controlled by the interaction between specific adhesion molecules such as endothelial ICAM-1 and leukocyte β(2) -integrins. Although attenuated expression of adhesion molecules on tumor endothelium has been proposed to represent a mechanism, which suppresses the intratumoral leukocyte infiltration, the relevance of adhesion molecules for leukocyte recruitment in tumor tissue is poorly understood. The present study is the first investigation of the role of ICAM-1 and β(2) -integrins in leukocyte recruitment in pancreatic and hepatocellular cancer in vivo, which was studied using knockout mice, intravital time-lapse microscopy and immunohistochemistry. We found that tumor tissue of both pancreatic and hepatocellular cancer was infiltrated with numerous active lymphoid and myeloid leukocytes, although the leukocyte extravasation rate in tumor blood vessels was very low. The knockout of LFA-1 (also known as α(L) β(2) integrin) strongly suppressed recruitment of CD8(+) T cells whereas no significant differences of leukocyte adhesion and infiltration were found in ICAM-1(-/-) and Mac-1(-/-) mice. Analysis of the interstitial leukocyte migration demonstrated that intratumoral leukocytes used haptokinetic type of migration, however, no significant differences of leukocyte migration between any knockout strains were found. We concluded that leukocyte recruitment in pancreatic and hepatocellular cancer is a slow-going process whose dynamics clearly contrasts to a high-speed leukocyte recruitment during acute inflammation. In contrast to acute inflammatory reaction, only LFA-1 controls recruitment of CD8(+) T-cells in both pancreatic and hepatocellular cancer, whereas ICAM-1 and Mac-1 are dispensable.     

Oscillating Laser Post-Processing of NiCrCoFeCBSi/WC Thermally Sprayed Coatings

In the present experimental study, the transverse oscillating laser beam technique was applied for the post-melting of metal matrix composite coatings, thermally sprayed with nickel-based self-fluxing NiCrCoFeCBSi alloy and 40 wt.% WC, to improve their hardness and wear resistance. The study was conducted using the single module optical fiber laser at 300 W power, >9554 W/cm² power density, 250–1000 mm/min laser speed, 1 mm and 2 mm transverse oscillation amplitude. Scanning electron microscopy, energy dispersive spectroscopy, Knop hardness measurements, and “Ball-on-disc” dry sliding tests were conducted to study the effect of the processing parameters on the molten pool geometry and microstructure, hardness, and tribology of the processed layers. Oscillating laser processing with an amplitude of 1 mm, 250–750 mm/min laser operating speed, and sample preheating to 400 °C gave a satisfactory result: wide and shallow molten pools of ~200–350 μm in depth, hardness between ~1100 and 1200 HV0.2 and minimum cracks obtained. The coatings obtained with laser beam oscillation and preheating, and ~1150 HV0.2 hardness showed an improvement in the wear resistance and friction coefficient (~0.33) of ~2.9 times and ~20%, respectively, compared with the respective values of the coatings remelted in furnace.     

Properties Evaluation of the Welded Joints Made by Disk Laser

The process of laser welding of sheets of HSLA (high-strength low-alloy steel), DP600 (dual-phase steel) and TRIP steels was investigated. A weld was successfully made in a double-sided hot-dip galvanized sheet with a thickness of 0.78–0.81 mm using a laser power of 2 kW per pass without any pretreatment of the weld zone. Microstructure studies revealed the presence of martensitic and ferritic phases in the weld zone, which could be associated with a high rate of its cooling. This made it possible to obtain good strength of the weld, while maintaining sufficient ductility. A relationship between the microstructural features and mechanical properties of welds made in the investigated steels has been established. The highest hardness was found in the alloying region of steels due to the formation of martensite. The hardness test results showed a very narrow soft zone in the heat affected zone (HAZ) adjacent to the weld interface, which does not affect the tensile strength of the weld. The ultimate tensile strength of welds for HSLA steel was 340–450 MPa, for DP600 steel: 580–670 MPa, for TRIP steel: ~700 MPa, respectively, exceeding the strength of base steels.     

Laser Boronizing of Additively Manufactured 18Ni-300 Maraging Steel Part Surface

The problem of insufficient wear resistance of maraging steels (MSt) has so far been solved mainly by the use of the thermochemical nitriding process, which has a number of limitations and disadvantages. In the present work, for MSt parts manufactured by laser powder bed fusion (LPBF), a more flexible laser alloying process was suggested as an alternative surface hardening process. The purpose of the present work is to give a better understanding on the possible hardening effect obtainable when amorphous boron is used as an alloying additive in relation with microstructural evolution and specific process parameters and to promote further development of this technology. For the alloying, a one kilowatt CO₂ laser was applied at 0.5–4.0 mm laser spot and 250–1500 mm/min laser operating speed, providing 50,955–796 W∙cm⁻² power density and 24.0–4.0 J∙mm⁻¹ heat input. Before laser processing, surfaces were covered with amorphous boron. The appropriate melt pool geometry was obtained at 0.5 mm laser spot, for which XPS analysis revealed an increase in boron concentration from ~3.1 to ~5.7 wt.% with a laser speed increase from 500 to 1500 mm/min. XRD analysis revealed domination of Fe₃B type borides along with the presence of FeB, Fe₂B, Ni₄B₃ borides, austenitic and martensitic phases. The microstructure of modified layers exhibited evolution from hypoeutectic microstructure, having ~630–780 HK0.5 hardness, to superfine lamellar nanoeutectic (~1000–1030 HK0.2) and further to submicron-sized dendritic boride structure (~1770 HK0.2). Aging of laser-boronized layers resulted in the change of phase composition and microstructure, which is mainly expressed in a plenty precipitation of Mo₂B₅ borides and leads to a reduction in hardness—more significant (by ~200–300 HK0.2) for hypoeutectic and hypereutectic layers and insignificant (by ~50 HK0.2) for near-eutectic. With the application of the laser boronizing technique, the hardness of MSt parts surface was increased up to ~three times before aging and up to ~2.3 times after aging, as compared with the hardness of aged MST part.     

Cadmium concentration in biological media of breast cancer patients

The study aimed to determine and compare cadmium (Cd) concentration in different biological media of breast cancer and benign breast tumor patients. Concentration of Cd was determined in breast tissue, urine, and blood of 57 breast cancer and 51 benign tumor patients. Two samples of breast tissue from each patient, i.e., tumor and healthy tissue were taken for the analysis. Cd in biological media was determined by atomic absorption spectrometry (Perkin–Elmer, Zeeman 3030). The mean Cd concentration in breast cancer patients was 0.053 μg/g (95% confidence intervals, CI 0.042–0.065) for tumor sample and 0.02 μg/g (95% CI 0.014–0.026) for healthy breast tissue sample (P < 0.001). In benign tumor patients, the figures were as follows: 0.037 μg/g (95% CI 0.023–0.051) and 0.032 μg/g (95% CI 0.018–0.047) (P > 0.05). Cd content in malignant tumor significantly differed from that in benign tumor (P < 0.01). Cancer patients with positive estrogen receptors (ERs) had significantly greater concentration of breast tissue Cd compared to patients with negative ERs (P = 0.035). Adjusted for creatinine, Cd in urine was significantly higher in cancer patients than in controls (P < 0.001). In cancer patients, a positive Spearman’s correlation was found between Cd in tumor and healthy breast tissue, blood (r = 0.44 and r = 0.39, respectively, P < 0.01). Correlation between Cd in urine of cancer patients and number of cigarettes smoked during lifetime was suggestive (r = 0.59, P = 0.075). The data obtained show higher concentration of cadmium in breast tumor and urine of cancer patients and support a possible relationship between cadmium and breast cancer.