Characteristics of and risk factors for biliary pathogen infection in patients with acute pancreatitis.

BACKGROUND: Infection in patients with acute pancreatitis, especially severe acute pancreatitis patients, is a common and important phenomenon, and the distributions and drug resistance profiles of bacteria causing biliary infection and related risk factors are dynamic. We conducted this study to explore the characteristics of and risk factors for bacterial infection in the biliary tract to understand antimicrobial susceptibility, promote the rational use of antibiotics, control multidrug-resistant bacterial infections and provide guidance for the treatment of acute pancreatitis caused by drug-resistant bacteria. METHODS: The distribution of 132 strains of biliary pathogenic bacteria in patients with acute pancreatitis from January 2016 to December 2020 were analyzed. We assessed drug resistance in the dominant Gram-negative bacteria and studied the drug resistance profiles of multidrug-resistant bacteria by classifying Enterobacteriaceae and nonfermentative bacteria. We then retrospectively analyzed the clinical data and risk factors associated with 72 strains of Gram-negative bacilli, which were divided into multidrug-resistant bacteria (50 cases) and non-multidrug-resistant bacteria (22 cases). RESULTS: The main bacteria were Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae and Pseudomonas aeruginosa. Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli had a 66.67% detection rate. Acinetobacter baumannii had more than 50.00% drug resistance to carbapenems, ESBL-producing Klebsiella pneumoniae had 100.00% drug resistance, and Pseudomonas aeruginosa had 66.67% resistance to carbapenems. Multivariate logistic regression analysis suggested that the administration of third- or fourth-generation cephalosporins was an independent risk factor for Gram-negative multidrug-resistant biliary bacterial infection in acute pancreatitis patients. CONCLUSION: Drug resistance among biliary pathogens in acute pancreatitis patients remains high; therefore, rational antimicrobial drug use and control measures should be carried out considering associated risk factors to improve diagnosis and treatment quality in acute pancreatitis patients.

Characterization of serum irisin in patients with severe acute pancreatitis.

BACKGROUND: Irisin, as a novel and versatile hormone secreted by skeletal myocytes and fat tissues, is reported to be involved in inflammation-related diseases; one of the main characteristics of severe acute pancreatitis (SAP) is inflammatory responses. This study aims to describe the characteristics of irisin in SAP. PATIENTS AND METHODS: Here, we enrolled 50 controls, 20 with no acute pancreatitis (AP), 20 AP, and 12 SAP patients, determined white blood cell, blood glucose, C-reactive protein, urine amylase, blood lipase, and serum irisin using an analyzer and enzyme-linked immunosorbent assay at the indicated time-points, analyzed the correlations of irisin with blood glucose, sex, and age, and then predicted the morality and complications of organ failure and/or exacerbations of comorbidities in SAP by irisin. RESULTS: The results showed no significant difference in all groups in the clinical parameters (P>0.05), except that white blood cell was significantly higher in no AP, AP, and SAP than the controls (P<0.05). In addition, irisin levels were significantly lower and maintained a steadily low trend in the process of SAP than others (P<0.05), whereas C-reactive protein, urine amylase, and blood lipase in the SAP and AP groups were higher than others and kept decreasing tendency (P<0.01). Moreover, the irisin level in female SAP patients was significantly higher than that in male patients, but no differences were found in the other groups (P>0.05). In addition, the correlation between irisin levels and blood glucose was better in the SAP group than that between irisin levels and age in SAP patients and controls, although a relatively better correlation was found in SAP patients than the controls. Finally, the prognostic significance of mortality and complications of SAP according to irisin levels represented significantly, especially for complications of organ failure and/or exacerbations of comorbidities in female SAP. CONCLUSION: Therefore, serum irisin level has unique characteristics and may be an independent factor and useful to predict the mortality, and complications in SAP patients, especially in female SAP patients.

Bi-metallic boride electrocatalysts with enhanced activity for the oxygen evolution reaction.

Rational design and understanding of the intrinsic mechanism are critical to develop highly active and durable electrocatalysts. In this study, a series of bi-metallic boride catalysts based on Ni and Co were prepared, and their activities were evaluated. The synthesised Co-10Ni-B catalyst exhibited excellent activity for water splitting in a 1 M KOH electrolyte. The overpotential was 330 mV at a current density of 10 mA cm-2, better than previously reported mono-metallic borides and even IrO2. The synergistic effect of Co and Ni was proved by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The facile formation of critical intermediates CoOOH and NiOOH during the catalytic processes and a significant increase in surface area owing to the introduction of a second metal into mono-metallic boride were attributed to the superior catalytic performance of catalysts for the oxygen evolution reaction. A Co-10Ni-B-sp catalyst with a higher surface area than the Co-10Ni-B catalyst was also synthesised to evaluate the effect of a high surface area on the catalytic activity. A lower overpotential of 310 mV at a current density of 10 mA cm-2 was achieved.

Self-synthesized extracellular matrix contributes to mature adipose tissue regeneration in a tissue engineering chamber.

The development of an engineered adipose tissue substitute capable of supporting reliable, predictable, and complete fat tissue regeneration would be of value in plastic and reconstructive surgery. For adipogenesis, a tissue engineering chamber provides an optimized microenvironment that is both efficacious and reproducible; however, for reasons that remain unclear, tissues regenerated in a tissue engineering chamber consist mostly of connective rather than adipose tissue. Here, we describe a chamber-based system for improving the yield of mature adipose tissue and discuss the potential mechanism of adipogenesis in tissue-chamber models. Adipose tissue flaps with independent vascular pedicles placed in chambers were implanted into rabbits. Adipose volume increased significantly during the observation period (week 1, 2, 3, 4, 16). Histomorphometry revealed mature adipose tissue with signs of adipose tissue remolding. The induced engineered constructs showed high-level expression of adipogenic (peroxisome proliferator-activated receptor γ), chemotactic (stromal cell-derived factor 1a), and inflammatory (interleukin 1 and 6) genes. In our system, the extracellular matrix may have served as a scaffold for cell migration and proliferation, allowing mature adipose tissue to be obtained in a chamber microenvironment without the need for an exogenous scaffold. Our results provide new insights into key elements involved in the early development of adipose tissue regeneration.

In vivo dedifferentiation of adult adipose cells.

INTRODUCTION: Adipocytes can dedifferentiate into fibroblast-like cells in vitro and thereby acquire proliferation and multipotent capacities to participate in the repair of various organs and tissues. Whether dedifferentiation occurs under physiological or pathological conditions in vivo is unknown. METHODS: A tissue expander was placed under the inguinal fat pads of rats and gradually expanded by injection of water. Samples were collected at various time points, and morphological, histological, cytological, ultrastructural, and gene expression analyses were conducted. In a separate experiment, purified green fluorescent protein+ adipocytes were transplanted into C57 mice and collected at various time points. The transplanted adipocytes were assessed by bioluminescence imaging and whole-mount staining. RESULTS: The expanded fat pad was obviously thinner than the untreated fat pad on the opposite side. It was also tougher in texture and with more blood vessels attached. Hematoxylin and eosin staining and transmission electron microscopy indicated there were fewer monolocular adipocytes in the expanded fat pad and the morphology of these cells was altered, most notably their lipid content was discarded. Immunohistochemistry showed that the expanded fat pad contained an increased number of proliferative cells, which may have been derived from adipocytes. Following removal of the tissue expander, many small adipocytes were observed. Bioluminescence imaging suggested that some adipocytes survived when transplanted into an ischemic-hypoxic environment. Whole-mount staining revealed that surviving adipocytes underwent a process similar to adipocyte dedifferentiation in vitro. Monolocular adipocytes became multilocular adipocytes and then fibroblast-like cells. CONCLUSIONS: Mature adipocytes may be able to dedifferentiate in vivo, and this may be an adipose tissue self-repair mechanism. The capacity of adipocytes to dedifferentiate into stem cell-like cells may also have a more general role in the regeneration of many tissues, notably in fat grafting.

The angiogenic and adipogenic modes of adipose tissue after free fat grafting.

BACKGROUND: The major drawback of adipose grafting is its clinical unpredictability, which leads to surgeon and patient dissatisfaction. The mechanisms underlying angiogenesis and regeneration of the graft tissue are still unclear. METHODS: Mouse adipose tissue was processed using two different methods (fragmental and integral) and was used to identify the mode of angiogenesis of the graft. Cross-grafting of tissue from normal mice and transgenic mice expressing green fluorescent protein was used to observe the origin of cells during the adipose regeneration. RESULTS: Almost all the CD31 endothelial cells of the new vessels were derived from the recipient. The new vessels in the graft were mainly formed through recipient vessels growing into the graft rather than the reassembly of donor endothelial cells or the reconnection of recipient and donor vessels. Angiogenesis depends largely on recipient-site environment. The retention of donor-derived tissue dropped to only 10 percent 8 weeks after grafting, and the majority of the key regeneration cells, the CD34 cells, came from the recipient during adipogenesis (p < 0.05). In total, the retention of the recipient-derived tissue was up to 73 percent in the fragmental group and 47.5 percent in the integral group. CONCLUSIONS: The angiogenesis of the graft occurs by the classic "vessel branching" mode, in which the recipient plays a dominant role. The mode of graft tissue retention primarily involves CD34 adipose precursor cells derived from the recipient.

N2O decomposition over K/Na-promoted Mg/Zn-Ce-cobalt mixed oxides catalysts.

Three groups of cobalt mixed oxide catalysts (Mg/Zn-Co, Mg/Zn-Ce-C, K/Na-Mg/Zn-Ce-Co) were prepared by sol-gel or impregnation methods. The synergistic effects of transition metal, rare earth metal and alkali metal on cobalt mixed catalysts for nitrous oxide (N2O) decomposing to N2 and O2 were investigated. The experimental results revealed that the catalytic activity for N2O decomposition was promoted as Co²âº was replaced partially by Zn²âº/Mg²âº, moreover, the characterization analysis by XRD and XPS showed that Zn²âº/Mg²âº replaced Co²âº successfully into the spinel structure of Co3O4 and promoted significantly the catalytic activity. Especially, the addition of CeO2 and K2O/Na2O decreased the binding energy and resulted in an increase in the density of the electron cloud around Co and an improvement of the catalytic activity. Of the investigated cobalt mixed catalysts, the best catalytic activity was shown by 2% K-Zn0.5-Ce0.05-Co catalyst.

Tissue engineering chamber promotes adipose tissue regeneration in adipose tissue engineering models through induced aseptic inflammation.

Tissue engineering chamber (TEC) makes it possible to generate significant amounts of mature, vascularized, stable, and transferable adipose tissue. However, little is known about the role of the chamber in tissue engineering. Therefore, to investigate the role of inflammatory response and the change in mechanotransduction started by TEC after implantation, we placed a unique TEC model on the surface of the groin fat pads in rats to study the expression of cytokines and tissue development in the TEC. The number of infiltrating cells was counted, and vascular endothelial growth factor (VEGF) and monocyte chemotactic protein-1 (MCP-1) expression levels in the chamber at multiple time points postimplantation were analyzed by enzyme-linked immunosorbent assay. Tissue samples were collected at various time points and labeled for specific cell populations. The result showed that new adipose tissue formed in the chamber at day 60. Also, the expression of MCP-1 and VEGF in the chamber decreased slightly from an early stage as well as the number of the infiltrating cells. A large number of CD34+/perilipin- perivascular cells could be detected at day 30. Also, the CD34+/perilipin+ adipose precursor cell numbers increased sharply by day 45 and then decreased by day 60. CD34-/perilipin+ mature adipocytes were hard to detect in the chamber content at day 30, but their number increased and then peaked at day 60. Ki67-positive cells could be found near blood vessels and their number decreased sharply over time. Masson's trichrome showed that collagen was the dominant component of the chamber content at early stage and was replaced by newly formed small adipocytes over time. Our findings suggested that the TEC implantation could promote the proliferation of adipose precursor cells derived from local adipose tissue, increase angiogenesis, and finally lead to spontaneous adipogenesis by inducing aseptic inflammation and changing local mechanotransduction.

Development of a sensitive and specific immunological test for detecting pregnancy-associated plasma protein A in patients with acute coronary syndrome.

BACKGROUND: Pregnancy-associated plasma protein A (PAPP-A) was first found in the serum of pregnant women and then found to be associated with acute coronary syndrome (ACS). Unfortunately, the sensitivity and specificity of current detection methods are poor, so the present work aimed to improve them. The successful detection of PAPP-A could be widely applicable clinically. METHODS: We used affinity chromatography to purify the PAPP-A antigen, which was used to prepare the antibody. A biotin-avidin enzyme-linked immunosorbent assay (BA-ELISA) was developed to detect low levels of PAPP-A. Nonspecific reactions were excluded by using affinity chromatography and papain digestion to remove the Fc fragment of the antibody. RESULTS: The BA-ELISA method we developed was more sensitive than traditional ELISA, as all nonspecific reactions were excluded. Its sensitivity was 0.065 mIU/L and recovery of PAPP-A from samples was 98.51%. The specificity was also much better than with standard ELISA kits. CONCLUSIONS: Affinity chromatography and papain digestion have important effects on the assay specificity. The BA-ELISA method proved sensitive and nonspecific reactions were excluded. The method is easily carried out, so it is suitable for detecting PAPP-A in the serum of patients with ACS.

[Establishment of BA-ELISA method for detecting CEA in human sera].

AIM: To establish a sensitive biotin-avidin enzyme linked immunosorbent assay (BA-ELISA) method for detecting carcinoembryonic antigen (CEA) in serum. METHODS: CEA which had been purified by affinity chromatography was used to immunize the rabbits to produce polyclonal antibodies. Then the antibodies were connected with biotin and horseradish peroxidase (HRP). So BA-ELISA method was established on the basis of 96 microwell plates coated with biotinylated BSA. Finally we examined the sensitivity, specificity, stability and recovery rate of this system and compared the BA-ELISA method with the traditional ELISA, radioimmunoassay and chemiluminescence in detecting CEA concentrations. RESULTS: The stability of this system was proved good. The linear range was from 0.42 to 50 U/mL, the sensitivity was 0.42 U/mL, and the intra-differences together with inter-differences were less than 10.0%. There was significant difference between BA-ELISA and traditional ELISA, while there was no significant difference between BA-ELISA and radioimmunoassay. The regression equation of this method was y=0.04825+0.99674x and r=0.994, and there was no significant difference between the BA-ELISA and chemiluminescence. CONCLUSION: The BA-ELISA method we established to detect CEA was easy to operate, highly sensitive, low in price and suitable for application in clinical detection.

[Purification and identification of pregnancy associated plasma protein A].

AIM: To purify pregnancy associated plasma protein A (PAPP-A) from the pregnancy serum using the methods of G200 gel filtration, reverse affinity chromatography and DEAE ion exchange. METHODS: The male sera were purified by G200 gel filtration and injected into rabbits to obtain rabbit-anti-human antibodies. The antibodies were linked to CNBr-activated G25 gel to make the reverse affinity chromatography. The full-term pregnancy sera were collected and centrifuged, followed by G200 gel filtration, reverse affinity chromatography and DEAE ion exchange. ELISA and SDS-PAGE were performed to detect the activity and the purity of PAPP-A. RESULTS: As detected by the double diffusion, the rabbit-anti-human antibodies were active in the dilution of 1:16, and were further used for purification of PAPP-A. The PAPP-A exited in the last peak with the pH3.0 elutriant by SPA, the first peak by G200 gel filtration, the peak with 0.1 mol/L PBS elutriant by the reverse affinity chromatography, and the peak with 0.45 mol/L NaCl elutriant by the DEAE ion exchange. The SDS-PAGE results indicated that the triple treatments of the pregnancy sera by G200 gel filtration, the reverse affinity chromatography and the DEAE ion exchange effectively enhanced purity of PAPP-A, with a single protein band shown by Western blot, whereas a single purification method produced dirty bands. CONCLUSION: High purity PAPP-A has been obtained, ready for preparation of its monoclonal antibody. The study paves a way for development of PAPP-A based ELISA kits for clinical use.