The effect of preoperative biliary stent on postoperative complications after the resection of pancreatic head tumour / A preoperatív biliáris sztent hatása a posztoperatív szövodményekre hasnyálmirigyfej-daganat miatt végzett reszekciós mutéteink kapcsán

Introduction. A preoperative biliary stent is often inserted because of obstructive jaundice due to pancreatic head tumour. However, it can also be the source of complications too. Aim and method. We retrospectively analyzed our operations which were performed between 01.10.2017 and 31.12.2019 for pancreatic tumour in association with stent related mortality and morbidity. The multiresistant bacteria and the spectrum of microorganism of intraoperative bile samples were investigated. Results. 82 patients were operated on with pancreatic tumour. There were 63 pancreatic head resections, and 19 palliative operations. 63 pancreatic head resections were analyzed. There were 36 open and 27 laparoscopic operations. Extended operation was needed in 12 cases (5 portal vein resections, 2 splenectomies, 1 right hepatolobectomy, 1 right hemicolectomy, 2 liver metastasectomies and 1 hepatic artery resection). The average age of 36 stented patients of which 24 were men and 12 women were 65 and 64 years respectively. The average age of 27 non-stented patients of which 14 were men and 13 were women, were 67.9 and 58 years respectively. The bile culture proved to be positive 30/36(83%) in the stented group and 13/27(48%) in the non-stented group (P = 0.005). The 3 most common bacteria were E coli, Enterococcus fecalis and Klebsiella pneumoniae in both groups followed by the yeast of Candida. 8 multiresistant bacteria were noticed in the stented group. 6 were ESBL producing (P = 0.033) and 2 vancomycine resistant (P = 0.5) bacteria. 3 patients of the stented group and 2 patients of the non-stented group were lost during the first 30 days. There were 4/0 wound infections, 6/2 haemorrhages, 2/2 pancreatic fistulas, and 2/3 abdominal abscesses in the stented vs. non stented groups. The average length of stay was 19.47 days in the stented and 14.62 days in the non-stented groups (P = 0.14). Conclusion. With regard to the fact that biliary stent changes the bacterial flora it is important to choose the proper antibiotic prophylaxis to reduce morbidity. On the basis of our own results and the literature an effective antibiotic therapy is suggested against enterococcus and ESBL producing bacteria. The prophylaxis against yeast in particularly in immunocompromised cases should also be considered. Regular antibiotic resistance check-up is essential.

Effect of Silver Modification on the Photoactivity of Titania Coatings with Different Pore Structures.

Nanostructured photoactive systems are promising for applications such as air and water purification, including self-cleaning coatings. In this study, mesoporous TiO2 sol-gel coatings with different pore structures were prepared and modified with silver by two methods: the "mixing" method by adding AgNO3 to the precursor sol, and the "impregnation" method by immersing the samples in AgNO3 solution (0.03 and 1 M) followed by heat treatment. Our aim was to investigate the effects that silver modification has on the functional properties (e.g., those that are important for self-cleaning coatings). Transmittance, band gap energy, refractive index, porosity and thickness values were determined from UV-Vis spectroscopy measurements. Silver content and structure of the silver modified samples were characterized by X-ray photoelectron spectroscopy, Rutherford backscattering spectrometry, High-resolution transmission electron microscopy and Energy Dispersive X-ray Spectrometry elemental mapping measurements. Wettability properties, including photoinduced wettability conversion behavior were investigated by water contact angle measurements. Photoactivity was studied under both UV and visible light with rhodamine 6G and methylene blue dye molecules, at the liquid-solid and air-solid interfaces modeling the operating conditions of self-cleaning coatings. Samples made with "impregnation" method showed better functional properties, in spite of their significantly lower silver content. The pore structure influenced the Ag content achieved by the "impregnation" method, and consequently affected their photoactivity.

Accumulation of 2-Acetylamino-5-mercapto-1,3,4-thiadiazole in chitosan coatings for improved anticorrosive effect on zinc.

Chitosan (Chit) coatings were applied on zinc substrates by the dip-coating method. Subsequently, the coatings were impregnated with a corrosion inhibitor, 2-Acetylamino-5-mercapto-1,3,4-thiadiazole (AcAMT) to obtain an increased anticorrosive effect. The coating thickness and the AcAMT accumulation were determined using UV-Vis spectroscopy on glass and quartz substrates, respectively. The surface morphology and coverage were investigated with atomic force microscopy. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to investigate the protective properties of the impregnated coatings. The chitosan coatings facilitated the accumulation of the corrosion inhibitor inside the polymeric matrix (a multiplication of 380 times compared to the impregnating solution concentration was calculated), channeling high amounts of AcAMT to the Zn surface, which resulted in an inhibition efficiency of >90%. This effect demonstrates the applicability of chitosan coatings as carriers for corrosion inhibitors, significantly reducing the amount of inhibitor needed to achieve good anticorrosive effects.

Robust Contact Angle Determination for Needle-in-Drop Type Measurements.

One of the main approaches for contact angle determination using sessile drops with a missing apex (e.g., because of the presence of the needle tip) is the polynomial drop-profile fitting method. The major disadvantage of this fitting procedure is that the derived contact angle is highly sensitive to the polynomial order and the number of pixels involved in the actual fit. In the present work, an easily implementable method is introduced to effectively tackle these drawbacks. Instead of fitting the drop-profile itself, the polynomial fitting is applied to the difference between the drop profile and the circumcircle, independently for both sides of the drop. The derivative value of this difference at the contact point is used to correct the slope obtained analytically from the circumcircle. It is shown that this approach allows the robust determination of the contact angle with high (≤0.6°) accuracy in a straightforward manner, and the results are not affected by the actual contact angle, drop volume, or the resolution of the captured image. Validation of this new approach is also given in the contact angle range of 20°-150° by comparing the results to the values calculated by the Young-Laplace fit.

Eco-friendly indigo carmine-loaded chitosan coatings for improved anti-corrosion protection of zinc substrates.

Chitosan (Chit) coatings were prepared on zinc and glass substrates by dip-coating method. The coatings were impregnated with a non-toxic compound, indigo carmine (IC). The novel, eco-friendly, IC-loaded chitosan coatings were characterized morpho-structurally, and their corrosion protection behavior was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The surface properties of the coated samples were evaluated by wettability measurements. The thickness of the native chitosan layers and the stability of the impregnated layers in terms of dye release on glass substrates were studied by UV-vis spectrophotometry. The good corrosion inhibiting efficiency of the coatings (>90%) was attributed to the ionic crosslinking of the positively charged Chit with negatively charged IC. The Chit-IC coatings can be successfully used as model systems for chitosan-based coatings incorporating ionic inhibitors and in less demanding applications, such as temporary protective coatings for metals, removable on demand by scrubbing with mild acidic solutions.

Bilayered (silica-chitosan) coatings for studying dye release in aqueous media: The role of chitosan properties.

Chitosan and bilayered--Rhodamine 6G impregnated silica-chitosan--coatings (300-3000 nm thick) were prepared and investigated as a model for controlled drug release. Properties of native, ionically (sodium triphosphate) and covalently (glutaraldehyde) cross-linked layers of chitosan in contact with aqueous phase (modeling human blood pH of ca. 7.3) were investigated. The cross-linking was confirmed by attenuated total reflection (ATR) Fourier transform infrared (FTIR), energy-dispersive spectroscopy (EDS) and solid state (13)C nuclear magnetic resonance (NMR) spectroscopy. The evolution of advancing water contact angles as a function of time was measured, and from the results restricted mobility of polymer segments in the interfacial layer of cross-linked chitosan coatings were assumed. Spectroscopic ellipsometry measurements showed that covalent cross-linking leads to a lowered, while ionic cross-linking to an increased swelling degree of chitosan layers. Despite the swelling behavior both cross-linked chitosan layers showed significant retard effect on dye release from the bilayered coatings.