Enzymatic characteristics of a recombinant protease (rPepD) from Aspergillus niger expressed in Pichia pastoris.

The Aspergillus niger AS3.350 protease gene (pepD) was successfully cloned and expressed in Pichia pastoris KM71. The rPepD activity was 331.5 U/ml, and the optimum temperature and pH were 45 °C and 8-9 respectively. In addition, enzyme activity was significantly inhibited by PMSF, EDTA, Mg2+, Fe2+ and Zn2+ ions, and stimulated by Ca2+ which selectively bound to the T302 and D323 residues. Mutation in either or both of the residues inhibited rPepD expression, indicating that binding to Ca2+ is necessary for PepD expression and activity. The rPepD showed a wide substrate range, and was particularly selective to those with hydrophobic amino acids. The degree of rPepD-mediated hydrolysis of soy protein isolate, corn flour and gluten meal were 8.7%, 38.1% and 33.6% respectively, which was higher than that by Alcalase, indicating that rPepD has potential applications in the food processing industry.

Ilexgenin A inhibits mitochondrial fission and promote Drp1 degradation by Nrf2-induced PSMB5 in endothelial cells.

Atherosclerosis (AS) is one of important events involving in the pathological process of coronary artery disease. Many traditional Chinese medicines have been widely used for the treatment of AS. Previous studies have demonstrated that Ilexgenin A (IA) obtained from Ilex hainanensis Merr. could improve AS development. However, its underlying mechanism is still unknown. This study was conducted to explore the possible targets and mechanisms involving in the anti-atheroclerosis effect of IA. The results showed IA significantly promoted NO production, reduced reactive oxygen species (ROS) generation, and inflammatory cytokine production induced by palmitate (PA) in endothelial cells, demonstrating IA could improve endothelial dysfunction. Meanwhile, IA dramatically inhibited dynamin-related protein 1 (Drp1) expression and mitochondrial fission induced by PA whereas proteasome inhibitor epoxomicin attenuated its effect on Drp1 expression, indicating IA decreased Drp1 expression with regulation of proteasome. Furthermore, IA also could increase the expression of proteasome subunit beta type5 (PSMB5) and activate nuclear factor-like 2 (Nrf2). Nrf2 knockdown eliminated the induction effect of IA on PSMB5 expression while abrogated its inhibition on ROS generation and mitochondrial fission stimulated by PA. These results demonstrated that IA could promote PSMB5 expression in an Nrf2-dependent manner, resulting in the suppression of mitochondrial fission, and thus improve endothelial dysfunction. These findings laid a foundation to the future development of IA as an agent to the prevention and treatment of AS.

High-level expression, purification, and enzymatic characterization of a recombinant Aspergillus sojae alkaline protease in Pichia pastoris.

An alkaline protease (Ap) was cloned from Aspergillus sojae GIM3.33 via RT-PCR technique. A truncated Ap without the signal peptide was successfully expressed in the Pichia pastoris KM71 strain. The following describes the optimal process conditions for the recombinant engineering of a strain expressing a recombinant Ap (rAp) in a triangular flask: inoculum concentration OD600 value 20.0 in 40 mL working volume (in 500 mL flasks), methanol addition (1.0%; volume ratio), 0.02% biotin solution (60 µL), and YNB primary concentration (13.0 g/L). Under these conditions, the protease activity of rAp in the fermentation broth reached 400.4 ±â€¯40.5 U/mL after induction for three days. The rAp was isolated and purified, and its enzymatic characteristics were tested. Its optimal pH was 10.0, and it remained stable in a pH range of 7.0-10.0. Its optimal temperature was 45 °C and it retained >50% activity at 40 °C for 60 min. The rAp activity was significantly inhibited by PMSF, Zn2+ and Fe2+ and the rAp had a broad substrate specificity for natural proteins and synthetic peptide substrates, and preferred substrates at P1 position with large hydrophobic side-chain groups. Compared to Papain (8.7%) and Alcalase (12.2%), the degree of hydrolysis of rAp to soy protein isolate was 16.5%; therefore, rAp was a good candidate for the processing of food industry byproducts.

Surgical management of persistent left superior vena cava associated with an absent right superior vena cava.

A case of persistent left with absent right superior vena cava accompanied with atrial septal defect in a six-year-old girl is presented. This rare venous malformation was diagnosed incidentally during surgery when the pericardium was incised. An L-shape cannula was directly inserted into the left superior vena cava for cardiopulmonary bypass. The atrial septal defect was closed with a fresh autologous pericardial patch. The surgical management of this rare anomaly is the subject of this review.

Intercostal artery aneurysm associated with coarctation of aorta in an adult.

Intercostal artery aneurysms associated with coarctation of aorta (CoA) are rare and their natural histories are poorly understood. This report describes the surgical correction of this anomaly in an adult without performing extracorporeal circulation. The coarctated segment of aorta and intercostal artery aneurysm were resected, and the continuity of the descending aorta was reestablished with an interposed vascular graft.

The feather degradation mechanisms of a new Streptomyces sp. isolate SCUT-3.

Feather waste is the highest protein-containing resource in nature and is poorly reused. Bioconversion is widely accepted as a low-cost and environmentally benign process, but limited by the availability of safe and highly efficient feather degrading bacteria (FDB) for its industrial-scale fermentation. Excessive focuses on keratinase and limited knowledge of other factors have hindered complete understanding of the mechanisms employed by FDB to utilize feathers and feather cycling in the biosphere. Streptomyces sp. SCUT-3 can efficiently degrade feather to products with high amino acid content, useful as a nutrition source for animals, plants and microorganisms. Using multiple omics and other techniques, we reveal how SCUT-3 turns on its feather utilization machinery, including its colonization, reducing agent and protease secretion, peptide/amino acid importation and metabolism, oxygen consumption and iron uptake, spore formation and resuscitation, and so on. This study would shed light on the feather utilization mechanisms of FDBs.

Heterologous expression and characterization of an antifungal chitinase (Chit46) from Trichoderma harzianum GIM 3.442 and its application in colloidal chitin conversion.

In this study, a chitinase gene, Chit46 from a mycoparasitic fungus Trichoderma harzianum was successfully expressed in Pichia pastoris with a high heterologous chitinase production of 31.4 U/mL, much higher than the previous reports. The active center and substrate binding pocket of the recombinant Chit46 (rChit46) were analyzed and the effects of pH, temperature, metal ions and glycosylation on its activity were tested. rChit46 effectively hydrolyzed colloidal chitin with a high conversion rate of 80.5% in 3 h and the chitin hydrolysates were mainly composed of (GlcNAc)2 (94.8%), which make it a good candidate for the green recycling of chitinous waste. rChit46 could also significantly inhibit growth of the phytopathogenic fungus Botrytis cinerea, which endowed it with the potential as a biocontrol agent.

Reply to: Comments on "Nomograms based on inflammatory biomarkers for predicting tumor grade and micro-vascular invasion in stage I/II hepatocellular carcinoma".

We appreciate to receive commentary from Dr Guangtong Deng and Dr Liang Xiao to our article, "Nomograms based on inflammatory biomarkers for predicting tumor grade and micro-vascular invasion in stage I/II hepatocellular carcinoma". First, neutrophil-to-lymphocyte ratio (NLR) and derived NLR (dNLR) are two different parameters. Some studies show that NLR is inconsistent with dNRL in prognostic value through multivariate Cox regression, therefore, it is reasonable that both NLR and dNLR entered into multivariate analysis simultaneously. Second, it is common that articles of predictive nomograms turned continuous variables into categorical variables. The reason is that the categorization of patient clinical variables is beneficial to doctors to make decisions based on the risk level of individual patients in clinical. At last, multicenter validation is quite difficult and we have listed the shortcomings in the limitations of our article. Further validation will need the joint efforts by other institutions.

Nomograms based on inflammatory biomarkers for predicting tumor grade and micro-vascular invasion in stage I/II hepatocellular carcinoma.

Background: Increasing evidences reveal that inflammation plays a critical role in tumorigenesis and progression. We aimed to develop the nomograms based on inflammatory biomarkers to predict micro-vascular invasion (MVI) and tumor grade in stage I/II hepatocellular carcinoma (HCC).Methods: A retrospective cohort of 627 patients with stage I/II HCC between January 2007 and December 2014 was included in the study. Logistic regression was performed to identify the independent risk factors of tumor grade and MVI. The significant predictors including neutrophil-to-lymphocyte ratio (NLR), derived neutrophil-to-lymphocyte ratio (dNLR), lymphocyte-to-monocyte ratio (LMR), tumor volume age, and tumor size were subsequently incorporated to build the nomograms. The prediction accuracies of the nomograms were evaluated using the area under the receiver operating characteristic (ROC) curve.Results: The independent risk factors for tumor grade were NLR, dNLR, and tumor volume (P<0.001, P=0.001, and P<0.001, respectively), which were assembled into tumor grade nomogram. MVI nomogram was developed by dNLR, LMR, age, and tumor size (P<0.001, P<0.001, P<0.001, and P=0.001, respectively) which were the independent predictors for MVI. The area under the ROC curve of nomograms for predicting tumor grade and MVI were 0.727 (95% confidence intervals [CI]: 0.690-0.761) and 0.839 (95% CI: 0.808-0.867), respectively. Patients who had a nomogram score of less than 100 and 79 were considered to have high possibility of moderate grade and have low risks of MVI presence, respectively.Conclusion: We successfully developed nomograms predicting tumor grade and MVI based on inflammatory biomarkers with high accuracy, leading to a rational therapeutic choice for stage I/II HCC.

Grading effect of abnormal glucose status on arterial stiffness and a new threshold of 2-h post-load glucose based on a Chinese community study.

AIMS/INTRODUCTION: To investigate the relationship between various glucose metabolic status and arterial stiffness, and further explore the threshold of blood glucose indices for the risk of arterial stiffness. MATERIALS AND METHODS: The present cross-sectional study included 4,851 individuals from a Chinese community. Overnight fasting blood glucose and 2-h post-load glucose were sampled. Arterial stiffness was measured as brachial-ankle pulse wave velocity. The association was examined using generalized linear regression models. The threshold effect was explored using two piecewise linear regression models by the smoothing plot. RESULTS: After adjustment for covariates, isolated impaired fasting glucose, isolated impaired glucose tolerance, combined glucose intolerance and newly diagnosed diabetes mellitus were associated with a greater risk of arterial stiffness compared with normal glucose tolerance (B = 18.09, 95% confidence interval [CI] 0.42-35.76, P = 0.045; B = 28.51, 95% CI: 3.40-53.62, P = 0.026; B = 60.70, 95% CI: 38.37-83.04, P < 0.001; B = 95.06, 95% CI: 71.88-118.25, P < 0.001, respectively). Furthermore, there was a non-linear relationship between 2-h post-load glucose and arterial stiffness. A threshold for 2-h post-load glucose of 6.14 mmol/L was observed for the risk of arterial stiffness. CONCLUSIONS: Impaired fasting glucose, impaired glucose tolerance, combined glucose intolerance and newly diagnosed diabetes mellitus were related to a greater risk of arterial stiffness compared with normal glucose levels. A threshold for 2-h post-load glucose of 6.14 mmol/L probably exists for the risk of arterial stiffness.

Carbohydrate antigen 125 levels and clinical outcomes after off-pump coronary artery bypass grafting.

OBJECTIVES: The present study aimed to evaluate the prognostic value of preoperative carbohydrate antigen 125 (CA125) levels for clinical outcomes after off-pump coronary artery bypass grafting (OPCAB). METHODS: A total of 314 consecutive patients who underwent OPCAB were enrolled in this study and divided into three groups corresponding to baseline CA125 level tertiles. Clinical outcomes of these patients were followed up after 1 year. The primary endpoint was the incidence of combined major adverse cardiac events (MACE). RESULTS: Event-free survival was significantly associated with the CA125 tertile (log-rank P=0.021); specifically, hazard ratios (HRs) increased progressively from CA125 tertile 1 to tertile 3 [vs. tertile 1: tertile 2 h=1.8; 95% confidence interval (CI): 1.1-2.8, P=0.040; tertile 3 h=2.9; 95% CI: 1.1-8.1, P=0.018]. In the first multivariate Cox regression analytical model (all variables except EuroSCORE), CA125 was an independent predictor of MACE (HR=1.1, 95% CI: 1.0-2.4, P=0.016). In a second model (CA125 levels and EuroSCORE only), CA125 remained an independent predictor of MACE (HR=1.1, 95% CI: 1.0-1.3, P=0.036). CONCLUSION: An increased preoperative CA125 level is an independent predictor of worse clinical outcomes after OPCAB during a 1-year follow-up.

Left atrial endocardial dysfunction and platelet activation in patients with atrial fibrillation and mitral stenosis.

OBJECTIVE: This study demonstrated left atrial endocardial dysfunction and platelet activation in patients with atrial fibrillation and mitral stenosis. METHODS: Study included 80 patients with mitral stenosis and atrial fibrillation (40 each with and without left atrial thrombosis), 15 healthy volunteers, and 10 left atrial appendage (LAA) specimens from donor hearts. Blood samples were collected through peripheral vein and left atrium, with peripheral blood samples of volunteers as controls. LAA specimens were collected during operations. LAA expressions of von Willebrand factor (vWF) and P-selectin were determined immunohistochemically; plasma concentrations were measured by enzyme-linked immunosorbent assay. LAA expressions of vWF and P-selectin genes in were quantitated with real-time fluorescent quantitative polymerase chain reaction. RESULTS: The difference in vWF and P-selectin plasma levels between left atrial and peripheral venous blood was not significant; however, peripheral plasma levels of vWF and P-selectin were significantly higher in those with thrombosis than without thrombosis, which in turn were higher than in healthy subjects. Both vWF and P-selectin proteins were stained in both left atrial endocardium and cardiomyocytes. The normalized vWF gene expression relative to control was 3.04 in patients with thrombosis and 2.16 in those without thrombosis (P<.01). The difference in P-selectin gene expressions among the groups was not significant. CONCLUSIONS: No differences were observed in plasma levels of vWF and P-selectin between left atrial and peripheral venous blood. Over expression of vWF gene in LAA may contribute to increased plasma vWF levels. P-selectin and vWF together may play a role in thrombosis.

Enzymatic characteristics of a recombinant neutral protease I (rNpI) from Aspergillus oryzae expressed in Pichia pastoris.

A truncated neutral protease I (NpI) from Aspergillus oryzae 3.042 was expressed in Pichia pastoris with a high enzyme yield of 43101 U/mL. Its optimum pH was about 8.0, and it was stable in the pH range of 5.0-9.0. Its optimum temperature was about 55 °C and retained >90% activity at 50 °C for 120 min. Recombinant NpI (rNpI) was inhibited by Cu(2+) and EDTA. Eight cleavage sites of rNpI in oxidized insulin B-chain were determined by mass spectrometry, and five of them had high hydrophobic amino acid affinity, which makes it efficient in producing antihypertensive peptide IPP from ß-casein and a potential debittering agent. The high degree of hydrolysis (DH) of rNpI to soybean protein (8.8%) and peanut protein (11.1%) compared to papain and alcalase makes it a good candidate in the processing of oil industry byproducts. The mutagenesis of H(429), H(433), and E(453) in the deduced zinc-binding motif confirmed rNpI as a gluzincin. All of these results show the great potential of rNpI to be used in the protein hydrolysis industry.