Mechanism and evolutionary analysis of Yarrowia lipolytica CA20 capable of producing erythritol with a high yield based on comparative genomics.

Combined mutagenesis is widely applied for the breeding of robust Yarrowia lipolytica used in the production of erythritol. However, the changes of genome after mutagenesis remains unclear. This study aimed to unravel the mechanism involved in the improved erythritol synthesis of CA20 and the evolutionary relationship between different Y. lipolytica by comparative genomics analysis. The results showed that the genome size of Y. lipolytica CA20 was 20,420,510 bp, with a GC content of 48.97%. There were 6330 CDS and 649 ncRNA (non-coding RNA) in CA20 genome. Average nucleotide identity (ANI) analysis showed that CA20 genome possessed high similarity (ANI > 99.50%) with other Y. lipolytica strains, while phylogenetic analysis displayed that CA20 was classified together with Y. lipolytica IBT 446 and Y. lipolytica H222. CA20 shared 5342 core orthologous genes with the 8 strains while harbored 65 specific genes that mainly participated in the substrate and protein transport processes. CA20 contained 166 genes coding for carbohydrate-active enzymes (CAZymes), which was more than that found in other strains (108－137). Notably, 4, 2, and 13 different enzymes belonging to glycoside hydrolases (GHs), glycosyltransferases (GTs), and carbohydrate esterases (CEs), respectively, were only found in CA20. The enzymes involved in the metabolic pathway of erythritol were highly conserved in Y. lipolytica, except for transaldolase (TAL1). In addition, the titer and productivity of erythritol by CA20 were 190.97 g/L and 1.33 g/L/h, respectively, which were significantly higher than that of WT5 wherein 128.61 g/L and 0.92 g/L/h were obtained (P< 0.001). Five frameshift mutation genes and 15 genes harboring nonsynonymous mutation were found in CA20 compared with that of WT5. Most of these genes were involved in the cell division, cell wall synthesis, protein synthesis, and protein homeostasis maintenance. These findings suggested that the genome of Y. lipolytica is conserved during evolution, and the variance of living environment is one important factor leading to genome divergence. The varied number of CAZymes existed in Y. lipolytica is one factor that contributes to the performance difference. The increased synthesis of erythritol by Y. lipolytica CA20 is correlated with the improvement of the stability of cell structure and internal environment. The results of this study provide a basis for the directional breeding of robust strains used in erythritol production.

Clinicopathological features of Epstein-Barr virus-associated gastric carcinoma: A systematic review and meta-analysis.

PURPOSE: The purpose of this meta-analysis was to explore the clinicopathological characteristics of Epstein-Barr virus (EBV)-associated gastric carcinoma (AGC) based on qualified studies. METHODS: PubMed, Cochrane and Embase databases updated to November 2017 were searched by the index words to identify relevant studies, including qualified randomized controlled trials, cohort studies or case-control studies. Studies were also identified by tracking reference lists. The meta-analysis included relative risks (RR), mean difference (MD) along with 95% confidence interval (95% CI) to analyze the main outcomes. RESULTS: A total of 35 studies were included in this meta-analysis with 7540 cases and 950 Epstein-Barr virus associated gastric cancer (EBVaGC) cases. The results indicated the EBV infection rate was significantly higher in males than in females (OR, 0.42; 95%CI 0.35-0.52), and the EBV infection rate was significantly higher in the diffuse type than in intestinal type (OR, 1.56; 95%CI 1.24-1.97). Besides, there was no marked association of EBV infection rate with lymph node metastasis (OR, 0.73; 95%CI 0.41-1.29), age (OR, 0.78; 95%CI 0.61-1.00) and pathologic tumor stage (OR, 1.11; 95%CI 0.90-1.38). The results of funnel plot, Begg's and Mazumdar's rank test, and Egger's test all showed no significant publication bias. CONCLUSIONS: In this meta-analysis, EBV infection rate was significantly higher in males and in diffuse cancer type. However, there was no marked association with lymph node metastasis, age and pathologic tumor stage. Thus, EBV-positive gastric cancer has distinct clinicopathological features.

Elevation of neuron-specific enolase and S-100beta protein level in experimental acute spinal cord injury.

We evaluated the protein levels of neuron-specific enolase (NSE) and S-100beta in serum and cerebrospinal fluid (CSF) in an animal model of acute spinal cord injury and ascertained their relevance. Spinal cord injury was induced at the T8 level in rats. Enzyme-linked immunosorbent assay was used to measure the protein levels of NSE and S-100beta in both serum and CSF at different time points (30 min, 2 h, 6 h, 12 h and 24 h after induction of spinal cord injury). There existed a significant correlation between neurological deficits and the severity of spinal cord injury (p<0.05). Compared with the control group, the protein levels of NSE and S-100beta in serum and CSF significantly increased from 2 h after injury (p<0.05) and reached a maximum at 6 h. Within a certain time window, the protein levels of NSE and S-100beta in serum and CSF were closely related to the severity of injury level (p<0.05). The protein levels of NSE and S-100beta in serum and CSF significantly increased after experimental spinal cord injury in a time-dependent manner and thus may be considered specific biomarkers for acute spinal cord injury.

Establishment of a mechanical injury model of rat hippocampal neurons in vitro.

OBJECTIVE: To establish a simple, reproducible, and practical mechanical injury model of hippocampal neurons of Sprague-Dawley rats in vitro. METHODS: Hippocampal neurons isolated from 1-2-day old rats were cultured in vitro. Mild, moderate and severe mechanical injuries were delivered to the neurons by syringe needle tearing, respectively. The control neurons were treated identically with the exception of trauma. Cell damage was assessed by measuring the Propidium Iodide (PI) uptaking at different time points (0.5, 1, 6, 12 and 24 hours) after injury. The concentration of neuron specific enolase was also measured at some time points. RESULTS: Pathological examination showed that degeneration, degradation and necrosis occurred in the injured cultured neurons. Compared with the control group, the ratio of PI-positive cells in the injured groups increased significantly after 30 minutes of injury (P<0.05). More severe the damage was, more PI-positive neurons were detected. Compared with the control group, the concentration of neuron specific enolase in the injured culture increased significantly after 1 hour of injury (P<0.05). CONCLUSIONS: The established model of hippocampal neuron injury in vitro can be repeated easily and can simulate the damage mechanism of traumatic brain injury, which can be used in the future research of traumatic brain injury.

Is decompressive craniectomy for malignant middle cerebral artery infarction of any worth?

OBJECTIVE: Malignant middle cerebral artery (MCA) infarction is characterized by mortality rate of up to 80%. The aim of this study was to determine the value of decompressive craniectomy in patients presenting malignant MCA infarction compared with those receiving medical treatment alone. METHODS: Patients with malignant MCA infarction treated in our hospital between January 1996 and March 2004 were included in this retrospective analysis. The National Institute of Health Stroke Scale (NIHSS) was used to assess neurological status on admission and at one week after surgery. All patients were followed up for assessment of functional outcome by the Barthel index (BI) and modified Rankin Scale (RS) at 3 months after infarction. RESULTS: Ten out of 24 patients underwent decompressive craniectomy. The mean interval between stroke onset and surgery was 62.10 h. The mortality was 10.0% compared with 64.2% in patients who received medical treatment alone (P<0.001). The mean NIHSS score before surgery was 26.0 and 15.4 after surgery (P<0.001). At follow up, patients who underwent surgery had significantly better outcome with mean BI of 53.3, RS of 3.3 as compared to only 16.0 and 4.60 in medically treated patients. Speech function also improved in patients with dominant hemispherical infarction. CONCLUSION: Decompressive craniectomy in patients with malignant MCA infarction improves both survival rates and functional outcomes compared with medical treatment alone. A randomized controlled trial is required to substantiate those findings.

Correlation of matrix metalloproteinase-2, -9, tissue inhibitor-1 of matrix metalloproteinase and CD44 variant 6 in head and neck cancer metastasis.

This study aimed to explore the molecular mechanism in tumor invasion and metastasis. The expression of matrix metalloproteinase-2, -9 (MMP-2, MMP-9), tissue inhibitor-1 of matrix metalloproteinase (TIMP-1), cell adhesion molecule 44 variant 6 (CD44v6), HER2/neu and p53 was investigated in 154 patients with head and neck squamous cell carcinoma (SCC) by ABC and ImmunoMax immunohistochemical method. Their clinical relevance and correlation were analysed. The expression of MMP-2, MMP-9, TIMP-1, CD44v6, HER2/neu and p53 was found in cancer cells in 87.01%, 85.71%, 68.18%, 98.05%, 55.19% and 50.65% cases respectively. Linear regression and correlation analysis revealed that there was close positive relationship (P<0.05) between the expression of MMP-2 and MMP-9, TIMP-1 and CD44v6, HER2/neu and MMP-9, MMP-2 and p53. Up-regulation of MMP-2 was accompanied by advanced T stage (P<0.01). There was also a trend of MMP-2 expression being related with tumor metastasis. Increased expression of HER2/neu was found in patients with tumor recurrence(P<0.05). The expression of TIMP-1 was higher in laryngeal cancer than that in pharyngeal cancer, and higher in keratinizing and non-keratinizing SCC than that in basaloid SCC(P<0.05). These findings suggested that MMP-2 and MMP-9, HER2/neu and MMP-9, MMP-2 and p53 had a coordinate function in aggression of tumor; that MMP-2 had a more important function than MMP-9 in tumor invasion and metastasis; and that HER2/neu might serve as a biomarker for poor prognosis in HNSCC.