Application of Solvent-Assisted Dual-Network Hydrogel in Water-Based Drilling Fluid for Lost Circulation Treatment in Fractured Formation.

During oil and gas well construction, lost circulation caused substantial nonoperation time and extra costs, and hydrogel, resilient and environmentally friendly, was one of the major types of material for lost circulation treatment. To migrate the weak bonding and hydrothermal degradation of conventional single network hydrogels, dual network (DN) hydrogel was prepared and immersed in solvents of polyethylene glycol (PEG), ethylene glycol, and glycerol. The swelling of DN gels at different temperatures was studied with water content and swelling rate tests, and the gel structural and morphology was characterized with attenuated total reflectance infrared spectroscopy (ATR-IR) and scanning electron microscopy test. Then, the compression test and fracture plugging performance test were conducted to study the strength of the gel. The results show that compared to those in ethylene glycol and glycerin, DN gel after immersion in PEG (DN-PEG) exhibits greater compression strength and better plugging performance even at high temperatures. The compression strength of DN-PEG was twice that of DN hydrogel before immersion, and its fracture plug breaking pressure can reach over 10.0 MPa. After undergoing hydrothermal treatment at 90 °C, the compression strength of the DN-PEG was nearly 20 times that of the DN hydrogel, and the fracture plug breaking pressure was still 2.81 MPa. According to ATR-IR spectroscopy, as the molecular weight of the solvent increases, more hydroxyl groups in the PEG have better ability to bind with hydrogen bonds, which greatly inhibits the swelling and polymer chain breakage, thereby reducing hydrothermal degradation in the strength of the dual-network hydrogel. Our work proposed an effective method to reduce the degradation of hydrogel in water at high temperature, and the prepared DN-PEG hydrogel was a promising material for lost circulation treatments in fractured formation.

Bacteria reduce flagellin synthesis to evade microglia-astrocyte-driven immunity in the brain.

The immune response of brain cells to invading bacteria in vivo and the mechanism used by pathogenic bacteria to escape brain immune surveillance remain largely unknown. It is believed that microglia eliminate bacteria by phagocytosis based on in vitro data. Here we find that a small percentage of microglia in the brain engulf neonatal meningitis-causing Escherichia coli (NMEC), but more microglia are activated to produce tumor necrosis factor alpha (TNFα), which activates astrocytes to secrete complement component 3 (C3) involved in anti-bacterial activity. To evade anti-bacterial activity of the immune system, NMEC senses low concentration of threonine in cerebrospinal fluid (CSF) to down-modulate the expression of flagellin and reduce microglial TNFα and astrocyte C3 production. Our findings may help develop strategies for bacterial meningitis treatment.

Using circulating O-sulfotyrosine in the differential diagnosis of acute kidney injury and chronic kidney disease.

BACKGROUND: Sulfation of tyrosine, yielding O-sulfotyrosine, is a common but fixed post-translational modification in eukaryotes. Patients with increased circulating O-sulfotyrosine levels experience a faster decline in renal function with progression to end-stage renal disease (ESRD). In the present study, we measured serum O-sulfotyrosine levels in individuals with chronic kidney disease (CKD) and acute kidney injury (AKI) to explore its ability to differentiate AKI from CKD. METHODS: A total of 135 patients (20 with AKI and 115 with CKD) were recruited prospectively for liquid chromatography-mass spectrometry assessment of circulating O-sulfotyrosine. We also studied C57BL/6 mice with CKD after 5/6 nephrectomy (Nx). Blood samples were drawn from the tail vein on Day 1, 3, 5, 7, 14, 30, 60, and 90 after CKD. Serum separation and characterization of creatinine, blood urea nitrogen (BUN), and O-sulfotyrosine was performed. Thus, the time-concentration curves of the O-sulfotyrosine level demonstrate the variation of kidney dysfunction. RESULTS: The serum levels of O-sulfotyrosine were markedly increased in patients with CKD compared with AKI. Median O-sulfotyrosine levels in CKD patients versus AKI, respectively, were as follows:243.61 ng/mL(interquartile range [IQR] = 171.90-553.86) versus 126.55 ng/mL (IQR = 48.19-185.03, P = 0.004). In patients with CKD, O-sulfotyrosine levels were positively correlated with creatinine, BUN, and Cystatin C (r = 0.63, P < 0.001; r = 0.49, P < 0.001; r = 0.61, P < 0.001, respectively) by the multivariate linear regression analysis (ß = 0.71, P < 0.001; ß = 0.40, P = 0.002; ß = 0.73, P < 0.001, respectively). However, this association was not statistically significant in patients with AKI (r = - 0.17, P = 0.472; r = 0.11, P = 0.655; r = 0.09, P = 0.716, respectively). The receiver operating characteristic (ROC) analysis illustrated that the area under the curve was 0.80 (95% confidence interval [CI] 0.71-0.89; P < 0.001) and the optimal cut-off value of serum O-sulfotyrosine suggesting AKI was < 147.40 ng/mL with a sensitivity and specificity of 80.90 and 70.00% respectively. In animal experiments, serum levels of O-sulfotyrosine in mice were elevated on Day 7 after 5/6 nephrectomy (14.89 ± 1.05 vs. 8.88 ± 2.62 ng/mL, P < 0.001) until Day 90 (32.65 ± 5.59 vs. 8.88 ± 2.62 ng/mL, P < 0.001). CONCLUSION: Serum O-sulfotyrosine levels were observed correlated with degrading renal function and in CKD patients substantially higher than those in AKI patients. Thus serum O-sulfotyrosine facilitated the differential diagnosis of AKI from CKD.

Heparin-binding protein levels correlate with aggravation and multiorgan damage in severe COVID-19.

BACKGROUND: Critically ill coronavirus disease 2019 (COVID-19) patients may suffer persistent systemic inflammation and multiple organ failure, leading to a poor prognosis. RESEARCH QUESTION: To examine the relevance of the novel inflammatory factor heparin-binding protein (HBP) in critically ill COVID-19 patients, and evaluate the correlation of the biomarker with disease progression. STUDY DESIGN AND METHODS: 18 critically ill COVID-19 patients who suffered from respiratory failure and sepsis, including 12 cases who experienced a rapidly deteriorating clinical condition and six cases without deterioration, were investigated. They were compared with 15 age- and sex- matched COVID-19-negative patients with respiratory failure. Clinical data were collected and HBP levels were investigated. RESULTS: HBP was significantly increased in critically ill COVID-19 patients following disease aggravation and tracked with disease progression. HBP elevation preceded the clinical manifestations for up to 5 days and was closely correlated with patients' pulmonary ventilation and perfusion status. INTERPRETATION: HBP levels are associated with COVID-19 disease progression in critically ill patients. As a potential mediator of disease aggravation and multiple organ injuries that are triggered by continuing inflammation and oxygen deficits, HBP warrants further study as a disease biomarker and potential therapeutic target.

COVID-19: Look to the Future, Learn from the Past.

There is a current pandemic of a new type of coronavirus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The number of confirmed infected cases has been rapidly increasing. This paper analyzes the characteristics of SARS-CoV-2 in comparison with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV) and influenza. COVID-19 is similar to the diseases caused by SARS-CoV and MERS-CoV virologically and etiologically, but closer to influenza in epidemiology and virulence. The comparison provides a new perspective for the future of the disease control, and offers some ideas in the prevention and control management strategy. The large number of infectious people from the origin, and the highly infectious and occult nature have been two major problems, making the virus difficult to eradicate. We thus need to contemplate the possibility of long-term co-existence with COVID-19.

The Infection Rate of COVID-19 in Wuhan, China: Combined Analysis of Population Samples.

BACKGROUND: The coronavirus disease (COVID-19) pandemic began in Wuhan, China, in December 2019. Wuhan had a much higher mortality rate than the rest of China. However, a large number of asymptomatic infections in Wuhan may have never been diagnosed, contributing to an overestimated mortality rate. OBJECTIVE: This study aims to obtain an accurate estimate of infections in Wuhan using internet data. METHODS: In this study, we performed a combined analysis of the infection rate among evacuated foreign citizens to estimate the infection rate in Wuhan in late January and early February. RESULTS: Based on our analysis, the combined infection rate of the foreign evacuees was 0.013 (95% CI 0.008-0.022). Therefore, we estimate the number of infected people in Wuhan to be 143,000 (range 88,000-242,000), which is significantly higher than previous estimates. Our study indicates that a large number of infections in Wuhan were not diagnosed, which has resulted in an overestimated case fatality rate. CONCLUSIONS: Increased awareness of the original infection rate of Wuhan is critical for proper public health measures at all levels, as well as to eliminate panic caused by overestimated mortality rates that may bias health policy actions by the authorities.

A retrospective analysis of the treatment on abdominal aortic balloon occlusion-related thrombosis by continuous low-flow diluted heparin.

Thrombosis is one of the serious complications related to prophylactic balloon occlusion of the abdominal aorta (PBOAA). This study aims to retrospectively analyze the efficacy and safety of continuous low-flow infusion of diluted heparin saline to prevent this complication related to PBOAA and further to provide the theory and evidences for using PBOAA.A study was carried out at our hospital from March 2016 to December 2018. Women with pernicious placenta previa (PPP) were treated PBOAA to prevent massive bleeding during CS. According to whether continuous low-flow infusion of diluted heparin saline was used to prevent catheter-related thrombosis or not, they were divided into 2 groups, the test group and the control group. The incidence of thrombosis between the 2 groups was compared and the effective treatment of thrombosis was also discussed. The comparison of nonparametric values was accomplished by using Fisher exact test. Statistical significance was set at P < .05.There were 31 women with PPP who received PBOAA during CS who were included in our study. Six of 19 women in control group (31.6%) developed thrombotic complications, while none of 12 women in test group. There were statistically significant differences in the incidence of thrombosis between the 2 groups (P = .037). There was no statistically significant difference in the amount of estimated blood loss and blood transfusion during CS between the 2 groups, nor was there statistically significant difference in the hospital days after CS (P > .05). All 6 women with thrombotic complications had no positive symptoms and thrombotic sequelae. The managements of thrombus included systemic anticoagulation, catheter-directed thrombolysis, and catheter-directed anticoagulation. One of the 6 women was lost to follow-up, and the thrombus of the other 5 women were completely dissolved. No other adverse outcomes or complications related to PBOAA were observed in all women in this study.Continuous low-flow infusion of diluted heparin saline is a safe procedure when PBOAA is performed for patients with PPP. It can effectively reduce or even avoid thrombosis without increasing intraoperative blood loss during CS for PPP patients.

The Effect of microRNA-328 antagomir on erectile dysfunction in streptozotocin-induced diabetic rats.

The study aimed at exploring the effect of microRNA-328 (miR-328) antagomir on erectile dysfunction (ED) in streptozotocin (STZ)-induced diabetic rats. A total of 120 male Sprague-Dawley (SD) rats were selected for this study. Fifteen rats were assigned as the diabetic control group and 75 out of the remaining rats (105 diabetic rat models) were divided into five groups with 15 rats in each group: diabetic ED, diabetic ED+negative control (NC), diabetic ED+miR-328 antagomir, diabetic ED+sildenafil and diabetic ED+miR-328 antagomir+sildenafil groups. The cGMP/AGEs production levels were measured using enzyme-linked immunosorbent assay (ELISA) test. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were conducted for testing the expression level of miR-328, transcription and protein levels of endothelial nitric oxide synthase (eNOS) and dickkopf-3 (DKK3). The diabetic ED+miR-328 antagomir group had better erectile function, lower cGMP production level, transcription and protein levels of eNOS and DKK3 but higher AGEs production level than the diabetic control group. The diabetic control group showed higher cGMP production level transcription and protein levels of eNOS and DKK3 and lower production levels of AGEs and miR-328 than the diabetic ED and diabetic ED+NC groups. Our results indicated that miR-328 antagomir could improve ED in STZ-induced diabetic rats by regulating cGMP and AGEs.

Structure and gene cluster of the O-antigen of Escherichia coli O156 containing a pyruvic acid acetal.

The lipopolysaccharide of Escherichia coli O156 was degraded under mild acidic and alkaline conditions and the resulting polysaccharides were studied by sugar analysis and (1)H and (13)C NMR spectroscopy. The following structure of the pentasaccharide repeating unit of the O-polysaccharide was established: where Rpyr indicates R-configurated pyruvic acid acetal. Minor O-acetyl groups also were present and tentatively localized on the Gal residues. The gene cluster for biosynthesis of the O-antigen of E. coli O156 was analyzed and shown to be consistent with the O-polysaccharide structure.

Genetic Diversity of O-Antigens in Hafnia alvei and the Development of a Suspension Array for Serotype Detection.

Hafnia alvei is a facultative and rod-shaped gram-negative bacterium that belongs to the Enterobacteriaceae family. Although it has been more than 50 years since the genus was identified, very little is known about variations among Hafnia species. Diversity in O-antigens (O-polysaccharide, OPS) is thought to be a major factor in bacterial adaptation to different hosts and situations and variability in the environment. Antigenic variation is also an important factor in pathogenicity that has been used to define clones within a number of species. The genes that are required to synthesize OPS are always clustered within the bacterial chromosome. A serotyping scheme including 39 O-serotypes has been proposed for H. alvei, but it has not been correlated with known OPS structures, and no previous report has described the genetic features of OPS. In this study, we obtained the genome sequences of 21 H. alvei strains (as defined by previous immunochemical studies) with different lipopolysaccharides. This is the first study to show that the O-antigen gene cluster in H. alvei is located between mpo and gnd in the chromosome. All 21 of the OPS gene clusters contain both the wzx gene and the wzy gene and display a large number of polymorphisms. We developed an O serotype-specific wzy-based suspension array to detect all 21 of the distinct OPS forms we identified in H. alvei. To the best of our knowledge, this is the first report to identify the genetic features of H. alvei antigenic variation and to develop a molecular technique to identify and classify different serotypes.