[Mechanism of human airway epithelial cell injury induced by Candida albicans infection]

Objective: To investigate the immune mechanism of human airway epithelial cell injury induced by invasion of Candida albicans with different biofilm formation abilities. Methods: Twenty-five strains of Candida albicans isolated and cultured in General Hospital of Ningxia Medical University from June to December 2019 were selected, and quality control strain SC5314 was used as the standard strain. An in vitro model of Candida albicans biofilm was established, and the biofilm formation ability of different Candida albicans was detected by crystal violet staining and enzyme plate method. The absorbance value at 570 nm (A₅₇₀) was determined by enzyme plate method. A₅₇₀≥0.5, 0.25<A₅₇₀<0.5 and A₅₇₀≤0.25 indicated strong biofilm Candida albicans form (SBF), moderate biofilm Candida albicans form (DRF) and weak biofilm Candida albicans form (WBF), respectively. The gas-liquid phase culture model of human airway epithelial cells was isolated and established in vitro and divided into five groups, including blank control group (n=20), standard strain group (n=20), strong biofilm group (n=19), weak biofilm group (n=17) and fluconazole-resistant group (n=18).The morphology of the epithelial cells was observed by scanning electron microscope (SEM), and the expression of marker protein in the model was detected by immunofluorescence in vitro. The level of lactate dehydrogenase (LDH) in cells was detected by microplate method, and the secretion of β-defensin (hBD2), granulocyte macrophage colony stimulating factor(GM-CSF) and granulocyte colony-stimulating factor (G-CSF) was detected by enzyme-linked immunosorbent assay (ELISA). Results: The strong biofilm strains grew with interlacing mycelia, and very few yeast cells could be seen wrapped in them.SEM observed that the mycelia of epithelial cells in gas-liquid phase culture could actively invade epithelial cells, and the expression of acetylated tubulin and keratin in cilia were significantly reduced, while the expression of Ki67 was down-regulated.The LDH levels in the blank control group, standard strain group, strong biofilm group, weak biofilm group, and fluconazole-resistant group were (12.21±5.68), (46.35±6.35), (18.69±4.38), (12.56±3.69), and (13.48±4.28) U/L, respectively, with statistically significant differences (P<0.001). Compared with standard strain group, LDH level in strong biofilm group, weak biofilm group and fluconazole resistant group were significantly decreased (all P<0.01). The hBD2 levels of the five groups were (26.14±0.77), (56.18±0.83), (30.66±2.59), (29.22±0.48), (28.28±1.56) ng/L, respectively, with statistically significant differences(P<0.001). Compared with the blank control group, SC5314-treated epithelial cells induced an increase of intracellular hBD2 expression (P<0.001). The differences in the expression of GM-CSF and G-CSF between different groups were not statistically significant(all P>0.05). Conclusion: Strong biofilm Candida albican can inhibit cell proliferation, disrupt the integrity of epithelial cells and induce cell damage by down-regulating the expression of cell proliferation-related protein.

[Diagnostic value of serum amyloid A and C-reactive protein for predicting acute aortic dissection]

Objective: To explore the diagnostic value of serum amyloid A (SAA) and C-reactive protein (CRP) for predicting acute aortic dissection (AAD). Methods: One hundred and seventy-five AAD patients and 160 patients with acute coronary syndrome (disease control group) who were admitted to Cardio-cerebrovascular Disease Hospital of General Hospital of Ningxia Medical University from January 2018 to June 2020 were retrospectively selected. Meanwhile, 148 healthy subjects (healthy control group) who underwent physical examination were also enrolled. The latex-enhanced immunoturbidimetric assay and the latex immunoturbidimetric assay were used to determine the serum SAA and CRP levels of all subjects, and related clinical data were collected and analyzed. Univariate and multivariate logistic regression analyses were performed to analyze the independent risk factors, and the receiver operating characteristic (ROC) curve was drawn to calculate the diagnostic value of SAA and CRP for predicting AAD. Results: The levels of SAA and CRP in the AAD patient group ((165.7±7.4) mg/L and (76.0±4.0)mg/L) were significantly higher than those of the healthy control group ((6.5±0.4) mg/L and (3.9±0.2) mg/L) and the disease control group ((27.2±1.3) mg/L and (9.4±3.2) mg/L), with significant differences (all P<0.05). Compared with patients less than 60 years, levels of SAA and CRP in AAD patients over 60 years old decreased ((150.6±12.7) mg/L and (73.9±7.3) mg/L), and there were significant differences (both P<0.05). Likewise, SAA levels in AAD patients with high-risk pain characteristics over 6 h increased compared to those with pain less than 6 h, and there was a significant difference (P<0.05). SAA was positively correlated with CRP (r=0.053 4, P<0.05). ROC analysis showed that SAA and CRP levels were independently related to the risk of AAD (P=0.001), and the ROC curve of SAA for predicting AAD showed that the area under the curve (AUC) of type A aortic dissection (TAAD) and type B aortic dissection (TBAD) were 0.997 and 0.995, respectively (both P<0.001). And the ROC curve of CRP for predicting AAD demonstrated that the AUC of TAAD and TBAD were 0.998 and 0.991, respectively (both P<0.001). The best cut-off values of SAA and CRP for predicting AAD were 175.17 mg/L and 72.96 mg/L, respectively. Conclusion: Increased levels of SAA and CRP have high predictive value for AAD, and SAA combined with CRP is expected to serve as a laboratory marker to assist the diagnosis of AAD.

[The diagnostic value of eosinophilic and eosinophilic cationic proteins in blood and nasal secretions for allergic rhinitis]

Objective:To compare the diagnostic value of eosinophil and eosinophil cationin protein（ECP） in blood and nasal secretions for allergic rhinitis（AR）. Method:Collecting the blood samples of 33 patients with AR （AR group） and 40 healthy people（control group）, and test the concentration of ECP in serum and the percentage of eosinophil in blood. At the same time, collecting the nasal secretions samples of 33 patients with AR and 24 healthy people, and test the concentration of ECP and the percentage of eosinophils in nasal secretions. Using receiver operating characteristic curve（ROC） analysis, calculate the area under the curve（AUC） for each parameter and determine their predictive capabilities, then analyzing the correlation between each indicator and clinical symptom scores. Result:Compared with the healthy control group, the concentration of ECP and the percentage of eosinophil in blood and nasal secretion increased significantly（P<0.001） in patients with AR. The AUG of ECP concentration in nasal secretions was 0.965 9, when the cut-off value was 3.634, 100% sensitivity and 88% specificity were obtained; the AUG of eosinophil percentage in blood was 0.9087, and when its cut-off value was 4.6, 95% sensitivity and 73% specificity were obtained; the ECP concentration in serum had an AUG of 0.903, and when the cut-off value was 0.866, 90% sensitivity and 76% specificity were obtained; the AUG of nasal secretion eosinophil's percentage was 0.863 6, when its cut-off value is 0.72, 100% sensitivity and 73% specificity were obtained. Conclusion:For allergic rhinitis, ECP concentrate in nasal secretions is the ideal auxiliary diagnosis marker, and has the best predictive capability.

Critical role of DNA checkpoints in mediating genotoxic-stress-induced filamentous growth in Candida albicans

The polymorphic fungus Candida albicans switches from yeast to filamentous growth in response to a range of genotoxic insults, including inhibition of DNA synthesis by hydroxyurea (HU) or aphidicolin (AC), depletion of the ribonucleotide-reductase subunit Rnr2p, and DNA damage induced by methylmethane sulfonate (MMS) or UV light (UV). Deleting RAD53, which encodes a downstream effector kinase for both the DNA-replication and DNA-damage checkpoint pathways, completely abolished the filamentous growth caused by all the genotoxins tested. Deleting RAD9, which encodes a signal transducer of the DNA-damage checkpoint, specifically blocked the filamentous growth induced by MMS or UV but not that induced by HU or AC. Deleting MRC1, the counterpart of RAD9 in the DNA-replication checkpoint, impaired DNA synthesis and caused cell elongation even in the absence of external genotoxic insults. Together, the results indicate that the DNA-replication/damage checkpoints are critically required for the induction of filamentous growth by genotoxic stress. In addition, either of two mutations in the FHA1 domain of Rad53p, G65A, and N104A, nearly completely blocked the filamentous-growth response but had no significant deleterious effect on cell-cycle arrest. These results suggest that the FHA domain, known for its ability to bind phosphopeptides, has an important role in mediating genotoxic-stress-induced filamentous growth and that such growth is a specific, Rad53p-regulated cellular response in C. albicans.

[Study of the relationship between sIgE of dust mite in serum and nasal secretion of allergic rhinitis]

OBJECTIVE

To search for the relationship between specific IgE of Dermatophagoides farinae in the serum and that in the local secretion of perennial allergic rhinitis patients.

METHOD

The serum and nasal secretion of suspected patients were collected, then test the concentration of mite sIgE in the serum as well as that in the secretion. The results were analyzed at last.

RESULT

The relationship of mite sIgE concentration and logarithm of the concentration between the serum and the local secretion is obvious (relative coefficient is 0.675 and 0.846 respectively.)

CONCLUSION

Dertermining the Dermatophagoides farinae sIgE in the serum can reflect the local condition of suspected patients fairly well. While for some patients whose local condition is not according to the serum sIgE, testing the local sIgE is necessary to get a correct diagnose.

[Studies on elimination of mycoplasmas from cell line cultures]

Mycoplasmas were effectively eliminated from contaminated LTK and CHO cell lines by means of the antibiotic Tiamutin (10 micrograms/ml), while Kanamycin and Gentamycin were less potential. An elimination procedure which involved the consecutive treatment of the cell cloning over a periods of 21-28 days was adopted. This procedure was effective when applied to cell lines contaminated with unidentified and partially non-cultivable strains of mycoplasmas which could be detected by electronic microscope.