Innovations in pancreatic anastomosis technique during pancreatoduodenectomies.

PURPOSE: Pancreatic fistula following pancreatic resections is still a relevant complication. The present work shows the efforts of a single institute to decrease this problem. METHODS: A total of 130 patients (63 men, 67 women) with a mean age of 60 (range: 23-81) years were operated on between January 2013 and March 2020. The most frequent type of pancreatic resection was a Whipple procedure with partial antrectomy. During all operations, an innovative method was used, namely a modification of the purse-string suture pancreatojejunostomy. Moreover, an early drain removal policy was applied, based on the drain amylase level on the first and subsequent postoperative days. RESULTS: Mean postoperative hospital stay was 13 days (range: 7-75). The overall morbidity rate was 43.8%; the clinically relevant (grade B/C) pancreatic fistula (CR-POPF) rate was 6.9%. Delayed gastric emptying (DGE) was observed in 4% of the patients. The ratio of operative mortality was 0.7%; the reoperation rate was 5.3%. Based on the drain amylase level on the first postoperative day, two groups could be established. In the first one, the drain was removed early, on the fourth day in average (range: 2-6). In the other group, the drain was left in situ protractedly or reinserted later on. CONCLUSION: A single center's experience proves that the refinement of the technique can improve the results of pancreatic surgery.

Evolutionary Remodeling of Bacterial Motility Checkpoint Control.

Regulatory networks play a central role in the relationship between genotype and phenotype in all organisms. However, the mechanisms that underpin the evolutionary plasticity of these networks remain poorly understood. Here, we used experimental selection for enhanced bacterial motility in a porous environment to explore the adaptability of one of the most complex networks known in bacteria. We found that the resulting phenotypic changes are mediated by adaptive mutations in several functionally different proteins, including multiple components of the flagellar motor. Nevertheless, this evolutionary adaptation could be explained by a single mechanism, namely remodeling of the checkpoint regulating flagellar gene expression. Supported by computer simulations, our findings suggest that the specific "bow-tie" topology of the checkpoint facilitates evolutionary tuning of the cost-benefit trade-off between motility and growth. We propose that bow-tie regulatory motifs, which are widespread in cellular networks, play a general role in evolutionary adaptation.

Exponential signaling gain at the receptor level enhances signal-to-noise ratio in bacterial chemotaxis.

Cellular signaling systems show astonishing precision in their response to external stimuli despite strong fluctuations in the molecular components that determine pathway activity. To control the effects of noise on signaling most efficiently, living cells employ compensatory mechanisms that reach from simple negative feedback loops to robustly designed signaling architectures. Here, we report on a novel control mechanism that allows living cells to keep precision in their signaling characteristics - stationary pathway output, response amplitude, and relaxation time - in the presence of strong intracellular perturbations. The concept relies on the surprising fact that for systems showing perfect adaptation an exponential signal amplification at the receptor level suffices to eliminate slowly varying multiplicative noise. To show this mechanism at work in living systems, we quantified the response dynamics of the E. coli chemotaxis network after genetically perturbing the information flux between upstream and downstream signaling components. We give strong evidence that this signaling system results in dynamic invariance of the activated response regulator against multiplicative intracellular noise. We further demonstrate that for environmental conditions, for which precision in chemosensing is crucial, the invariant response behavior results in highest chemotactic efficiency. Our results resolve several puzzling features of the chemotaxis pathway that are widely conserved across prokaryotes but so far could not be attributed any functional role.

Ischaemic postconditioning reduces serum and tubular TNF-α expression in ischaemic-reperfused kidney in healthy rats.

OBJECTIVE: We studied the protective effects of postconditioning (PS) in healthy and hypercholesterolemic rats after renal ischaemia-reperfusion (IR) injury. We aimed to examine cytokine expression and apoptosis in tissue damage after revascularisation (TNF-α levels in serum and tissue). METHODS: Male Wistar rats (n = 32) were divided into four groups. The animals of normal feed groups (NF) were fed with normal rat chow and the cholesterol feed groups (CF) were fed with 1.5% cholesterol containing diet for 8 weeks. Anaesthetized rats underwent a 45-min cross-clamping in both kidney pedicles. Ischaemia was followed by 120-min reperfusion with or without PS protocol (group PS vs. IR). Postconditioning was induced by four intermittent periods of ischaemia-reperfusion of 15-s duration each. Serum cholesterol, triglyceride, urea and creatinine levels were determined. Proinflammation was characterized by the measurement of serum TNF-α. Tissue injury in kidney was determined by formaline-fixed, paraffin-embedded tissue sections. Tissue TNF-α levels were determined by immunohistochemistry. RESULTS: Significant elevation was observed in serum TNF-α level after IR injury in normal feed groups, which was reduced by PS. In CF group neither the elevation nor the postconditioning induced reduction were as significant as in the NF groups. In normal feed group PS caused a significant reduction in tissue TNF-α level which was significantly higher in CF. CONCLUSIONS: Ischaemic postconditioning proved to be an effective defense against IR in NF groups, but it was ineffective in CF groups in kidney tissue.

DNA/Ad5 vaccination with SIV epitopes induced epitope-specific CD4⁺ T cells, but few subdominant epitope-specific CD8⁺ T cells.

The goals of a T cell-based vaccine for HIV are to reduce viral peak and setpoint and prevent transmission. While it has been relatively straightforward to induce CD8(+) T cell responses against immunodominant T cell epitopes, it has been more difficult to broaden the vaccine-induced CD8(+) T cell response against subdominant T cell epitopes. Additionally, vaccine regimens to induce CD4(+) T cell responses have been studied only in limited settings. In this study, we sought to elicit CD8(+) T cells against subdominant epitopes and CD4(+) T cells using various novel and well-established vaccine strategies. We vaccinated three Mamu-A*01(+) animals with five Mamu-A*01-restricted subdominant SIV-specific CD8(+) T cell epitopes. All three vaccinated animals made high frequency responses against the Mamu-A*01-restricted Env TL9 epitope with one animal making a low frequency CD8(+) T cell response against the Pol LV10 epitope. We also induced SIV-specific CD4(+) T cells against several MHC class II DRBw*606-restricted epitopes. Electroporated DNA with pIL-12 followed by a rAd5 boost was the most immunogenic vaccine strategy. We induced responses against all three Mamu-DRB*w606-restricted CD4 epitopes in the vaccine after the DNA prime. Ad5 vaccination further boosted these responses. Although we successfully elicited several robust epitope-specific CD4(+) T cell responses, vaccination with subdominant MHC class I epitopes elicited few detectable CD8(+) T cell responses. Broadening the CD8(+) T cell response against subdominant MHC class I epitopes was, therefore, more difficult than we initially anticipated.

Examination of protective effect of ischemic postconditioning after small bowel autotransplantation.

Ischemia/reperfusion (I/R) injury is a serious condition that results from some surgical procedures, including intestinal transplantation. Ischemic postconditioning is defined as brief periods of reperfusion alternating with reocclusion applied during the early minutes after reperfusion. The objective of this study was to investigate the effect of ischemic postconditioning before small bowel autotransplantation. Total orthotopic intestinal autotransplantation was performed in 30 white domestic pigs. Grafts were stored in cold University of Wisconsin solution for 1, 3, or 6 hours. Duration of reperfusion was 3 hours in all grafts. Before reperfusion, the intestine was postconditioned via 3 cycles of ischemia for 30 seconds and reperfusion for 30 seconds (ischemic postconditioning protocol). Tissue from the small intestine was obtained after laparotomy (control group) and at the end of reperfusion periods. To monitor oxidative stress, tissue concentrations of malondialdehyde and reduced glutathione, and activity of superoxide dismutase were determined at spectrophotometry. Tissue damage on sections stained with hematoxylin- eosin was evaluated using a quantitative method (Scion Image software; Scion Corp, Frederick, Maryland). Our results demonstrated that ischemic postconditioning significantly decreased the reperfusion-ended lipid peroxidation value (mean +/- SEM, 142.0 +/- 7.1 micromol/g vs 125.0 +/- 2.1 micromol/g; P < .05). Moreover, the capacity and activity of endogenous antioxidant protective systems (glutathione 789+/-8.0 micromol/g vs 934 +/- 5.7 micromol/g, and superoxide dismutase 110 +/- 9 IU/g vs 126 +/- 4 IU/g; P < .05) remained higher in the ischemic postconditioning groups compared with tissues without ischemic postconditioning. At quantitative analysis, tissue injury was increased by the duration of cold preservation. The greatest injury was observed in the mucosal and submucosal layers and in the depth of crypts after 6 hours of preservation. Ischemic postconditioning significantly decreased intestinal wall injury in each group (P < .05). It was concluded that ischemic postconditioning before reperfusion mitigated oxidative stress and histologic damage during small bowel autotransplantation.

New strategy for synthesis and functionalization of carbon nanoparticles.

We describe a novel "one-step" combined synthesis and functionalization of carbon nanoparticles, using a new generation of all-in-one small submerged-arc plasma reactor that we have developed. We take advantage of long-lived free radicals generated by a submerged-arc helium atmosphere plasma and resident on the nanoparticle surfaces to supply ethylenediamine directly after the plasma to functionalize the carbon nanoparticles. XPS, TG/DTG, FTIR, and fluorescence tests confirm the viability of this new amination process. The nanoparticles are small and relatively uniformly sized. Their dispersibility in aqueous solution is significant.

Role of translational coupling in robustness of bacterial chemotaxis pathway.

Chemotaxis allows bacteria to colonize their environment more efficiently and to find optimal growth conditions, and is consequently under strong evolutionary selection. Theoretical and experimental analyses of bacterial chemotaxis suggested that the pathway has been evolutionarily optimized to produce robust output under conditions of such physiological perturbations as stochastic intercellular variations in protein levels while at the same time minimizing complexity and cost of protein expression. Pathway topology in Escherichia coli apparently evolved to produce an invariant output under concerted variations in protein levels, consistent with experimentally observed transcriptional coupling of chemotaxis genes. Here, we show that the pathway robustness is further enhanced through the pairwise translational coupling of adjacent genes. Computer simulations predicted that the robustness of the pathway against the uncorrelated variations in protein levels can be enhanced by a selective pairwise coupling of individual chemotaxis genes on one mRNA, with the order of genes in E. coli ranking among the best in terms of noise compensation. Translational coupling between chemotaxis genes was experimentally confirmed, and coupled expression of these genes was shown to improve chemotaxis. Bioinformatics analysis further revealed that E. coli gene order corresponds to consensus in sequenced bacterial genomes, confirming evolutionary selection for noise reduction. Since polycistronic gene organization is common in bacteria, translational coupling between adjacent genes may provide a general mechanism to enhance robustness of their signaling and metabolic networks. Moreover, coupling between expression of neighboring genes is also present in eukaryotes, and similar principles of noise reduction might thus apply to all cellular networks.

Ischaemic postconditioning reduces peroxide formation, cytokine expression and leukocyte activation in reperfusion injury after abdominal aortic surgery in rat model.

OBJECTIVE: We studied the protective effects of ischaemic postconditioning (PS) on ischemia-reperfusion injury of the lower extremities in a rat model of abdominal aortic intervention. We aimed to examine the evoked oxidative stress, cytokine expression and leukocyte activation after revascularisation surgery. METHODS: Anesthetized animals (48 Whistar rats) underwent a 60 min infrarenal aorta cross-clamping. After the ischaemic period, an intermittent 4 times 15 s reperfusion--15 seconds ischaemic episodes--were applied (ischaemic postconditioning: group PS). Then we started a 120 min reperfusion in the aorta. In untreated group animals underwent a long ischaemia (60 min) and the following reperfusion (group IR). Peripherial blood samples were collected before operation, and in early (5, 10, 15, 30, 60 and 120 min) reperfusion periods. Serum peroxide level, TNF-alpha concentration, myeloperoxidase (MPO) activity and PMA-induced leukocyte ROS production were measured. RESULTS: In PS group, plasma peroxide level elevation was significantly lower in very early reperfusion (5-30 min) comparing to non-conditioned IR group (10.04+/-1.9 microM/l vs. 16.91+/-3.67 microM/l, p<0.05). PS also reduced serum TNF-alpha concentration (167.41+/-31.26 microg/ml vs. 116.55+/-12.04 microg/ml, p<0.05), MPO activity (1.759+/-0.239 microM/ml vs. 1.22+/-0.126 microM/ml, p<0.05) and leukocyte activation detected by PMA-induced leukocyte ROS production (5.7+/-0.96 AU/10(3) cells vs. 4.63+/-0.69 AU/10(3) cells). CONCLUSIONS: Ischaemic postconditioning could reduce ROI production after IR in early reperfusion period, thus limiting ROI mediated tissue lesion, cytokine-leukocyte activation and inflammatory responses. PS seems to be an effective tool in vascular surgery to reduce reperfusion injuries after revascularization interventions.

Reperfusion injury and inflammatory responses following acute lower limb revascularization surgery.

After revascularization of an acute arterial occlusion the development of a serious ischaemic-reperfusion injury is a menacing challenge and a hard task in peripheral vascular surgery. A whale of evidences point to oxidative stress, as an important trigger, in the complex chain of events leading to reperfusion injury. In the present study authors aimed to examine oxidative stress parameters, antioxidant-prooxidant state and leukocyte adhesion molecules (CD11a and CD18) expression following acute revascularization surgery of lower limb.10 patients were examined in the prospective randomized study. Peripheral blood sample was collected in ischaemic period, and after reperfusion in the 2nd and 24th hours, and on 7th day. Superoxide-dismutase activity, reduced glutathion concentration and leukocytes free radical production were measured. The degree of lipidperoxidation was marked with the quantity of malondialdehyde. The expressions of adhesion molecules were measured with flowcytometry.The speed and rate of free radical production significantly increased in the early reperfusion (p<0.05). The level of antioxidant enzymes decreased after revascularization. The CD11a and CD18 expression of the granulocytes significantly (p<0.05) decreased right after the revascularization, but with a gradual elevation until the 7th day they exceed the ischaemic value. Our results showed a time specific turnover of the sensitive antioxidant-prooxidant balance after revascularization operation.

Plasma-mediated grafting of poly(ethylene glycol) on polyamide and polyester surfaces and evaluation of antifouling ability of modified substrates.

A simple cold plasma technique was developed to functionalize the surfaces of polyamide (PA) and polyester (PET) for the grafting of polyethylene glycol (PEG) with the aim of reducing biofilm formation. The surfaces of PA and PET were treated with silicon tetrachloride (SiCl4) plasma, and PEG was grafted onto plasma-functionalized substrates (PA-PEG, PET-PEG). Different molecular weights of PEG and grafting times were tested to obtain optimal surface coverage by PEG as monitored by electron spectroscopy for chemical analysis (ESCA). The presence of a predominant C-O peak on the PEG-modified substrates indicated that the grafting was successful. Data from hydroxyl group derivatization and water contact angle measurement also indicated the presence of PEG after grafting. The PEG-grafted PA and PET under optimal conditions had similar chemical composition and hydrophilicity; however, different morphology changes were observed after grafting. Both PA-PEG and PET-PEG surfaces developed under optimal plasma conditions showed about 96% reduction in biofilm formation by Listeria monocytogenes compared with that of the corresponding unmodified substrates. This plasma functionalization method provided an efficient way to graft PEG onto PA and PET surfaces. Because of the high reactivity of Si-Cl species, this method could potentially be applied to other polymeric materials.

Plasma-enhanced modification of xanthan gum and its effect on rheological properties.

The structure and rheological properties of xanthan gum (XG) modified in a cold plasma environment were investigated. XG was functionalized in a capacitively coupled 13.56-MHz radio frequency dichlorosilane (DS)-plasma conditions and, consecutively, in situ aminated by ethylenediamine. The surface structure of modified XG was evaluated on the basis of survey and high-resolution ESCA, FTIR, and fluorescence labeling techniques. The types of species generated in DS-plasma were reported using residual gas analysis (RGA). The aqueous solutions of modified XG were cross-linked and cured at room temperature to form stable gels. The dynamic rheological characteristics of virgin XG and functionalized and cross-linked XG were compared. It was found that parameters such as plasma treatment time and concentration of solutions can be optimized to form stable gels of XG. Thus, cold plasma technology is a novel, efficient, and nonenzymatic route to modify XG.

Plasma synthesis of carbon magnetic nanoparticles and immobilization of doxorubicin for targeted drug delivery.

Using dense medium plasma technology, carbon magnetic nanoparticles (CMNP) were synthesized at room temperature and atmospheric pressure. Based on results from X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy, we conclude that these nanoparticles are composed of spherical particles, 40-50 nm in diameter, with iron/iron oxide particles dispersed in a carbon-based host-structure. Thermal gravimetry/differential thermal gravimetry analysis shows these nanoparticles are stable to temperatures as high as 600 degrees C. The synthesized CMNP were treated by argon-plasma, aminated with ethylene diamine and subsequently activated by generating aldehyde groups on them. Free doxorubicin (DOX) molecules were then immobilized onto the surfaces of activated CMNP particles to form CMNP-DOX conjugates. The corresponding loading efficiency was determined. The in vitro antiproliferative activity of immobilized doxorubicin in the conjugates was demonstrated in tumor cell cytotoxicity assays. It is suggested that this CMNP-DOX system can be used for targeted drug-delivery systems.

Treatment of methyl tert-butyl ether contaminated water using a dense medium plasma reactor: a mechanistic and kinetic investigation.

Plasma treatment of contaminated water appears to be a promising alternative for the oxidation of aqueous organic pollutants. This study examines the kinetic and oxidation mechanisms of methyl tert-butyl ether (MTBE) in a dense medium plasma (DMP) reactor utilizing gas chromatography-mass spectrometry and gas chromatography-thermal conductivity techniques. A rate law is developed for the removal of MTBE from an aqueous solution in the DMP reactor. Rate constants are also derived for three reactor configurations and two pin array spin rates. The oxidation products from the treatment of MTBE-contaminated water in the DMP reactor were found to be predominately carbon dioxide, with smaller amounts of acetone, tert-butyl formate, and formaldehyde. The lack of stable intermediate products suggests that the MTBE is, to some extent, oxidized directly to carbon dioxide, making the DMP reactor a promising tool in the future remediation of water. Chemical and physical mechanisms together with carbon balances are used to describe the formation of the oxidation products and the important aspects of the plasma discharge.

Intracerebral haemorrhage and hepatitis C treatment.

We report 3 episodes of intracerebral haemorrhage in a population of 1460 hepatitis C infected patients. We suggest the possibility of a link between HCV and its treatment and the occurrence of this serious complication.