Nan fang yi ke da xue xue bao = Journal of Southern Medical University最新文献

Objective: To explore the effect of intestinal nitrates on the growth of Klebsiella pneumoniae and its regulatory mechanisms.

Methods: K. pneumoniae strains with nitrate reductase narG and narZ single or double gene knockout or with NarXL gene knockout were constructed and observed for both aerobic and anaerobic growth in the presence of KNO₃ using an automated bacterial growth analyzer and a spectrophotometer, respectively. The mRNA expressions of narG and narZ in K. pneumoniae in anaerobic cultures in the presence of KNO₃ and the effect of the binary regulatory system NarXL on their expresisons were detected using qRT-PCR. Electrophoretic mobility shift assays (EMSA) and MST analysis were performed to explore the specific regulatory mechanisms of NarXL in sensing and utilizing nitrates. Competitive experiments were conducted to examine anaerobic growth advantages of narG and narZ gene knockout strains of K. pneumoniae in the presence of KNO₃.

Results: The presence of KNO₃ in anaerobic conditions, but not in aerobic conditions, promoted bacterial growth more effectively in the wild-type K. pneumoniae strain than in the narXL gene knockout strain. In anaerobic conditions, the narXL gene knockout strain showed significantly lowered mRNA expressions of narG and narZ (P < 0.0001). EMSA and MST experiments demonstrated that the NarXL regulator could directly bind to narG and narZ promoter regions. The wild-type K. pneumoniae strain in anaerobic cultures showed significantly increased expressions of narG and narZ mRNAs in the presence of KNO₃ (P < 0.01), and narG gene knockout resulted in significantly attenuated anaerobic growth and competitive growth abilities of K. pneumoniae in the presence of KNO₃ (P < 0.01).

Conclusion: The binary regulatory system NarXL of K. pneumoniae can sense changes in intestinal nitrate concentration and directly regulate the expression of nitrate reductase genes narG and narZ to promote bacterial growth.

Objective: To investigate the therapeutic effect of Euryale ferox seed shell extract on oral ulcer in rats and its underlying mechanism.

Methods: The contents of polyphenols and flavonoids in Euryale ferox seed shells were determined by Folin-phenol assay and aluminum nitrate colorimetry, respectively. DPPH·, ABTS⁺·, ·OH and·O₂^- scavenging experiments were performed to evaluate the antioxidant activities of Euryale ferox seed shell extract in vitro. In a rat model of oral ulcer induced by burning with glacial acetic acid, the therapeutic effect of Euryale ferox seed shell extract was assessed by detecting changes in serum levels of oxidative factors by enzyme-linked immunosorbent assay (ELISA) and observing pathological changes of the ulcerous mucosa using HE staining; the therapeutic mechanism of the extract was explored by detecting the expression levels of Keap1, Nrf2, Nes-Nrf2 and HO-1 proteins in ulcerous mucosa using Western blotting.

Results: The ethyl acetate extract of Euryale ferox seed shells contained 306.74±1.04 mg/g polyphenols and 23.43±0.61 mg/g flavonoids and had IC₅₀ values for scavenging DPPH· and ABTS⁺· free radicals of 3.42 ± 0.97 μg/mL and 3.32 ± 0.90 μg/mL, respectively. In the rat models, the ethyl acetate extract significantly ameliorated oral mucosal ulcer, increased serum CAT level, and decreased serum MDA level. The protein expression levels of Nes-Nrf2 and HO-1 were increased and Keap1 protein expression was lowered significantly in the ulcerous mucosa of the rats after treatment with the extract (P<0.05 or 0.01).

Conclusion: The therapeutic effect of Euryale ferox seed shell extract on oral ulcers in rats is mediated probably by activation of the Keap1/Nrf2/HO-1 signaling pathway.

Objective: To identify the key genes differentially expressed in Wilms tumor and analyze their potential impacts on prognosis and immune responses of the patients.

Methods: High-throughput RNA sequencing was used to identify the differentially expressed mRNAs in clinical samples of Wilms tumor and paired normal tissues, and their biological functions were analyzed using GO, KEGG and GSEA enrichment analyses. The hub genes were identified using STRING database, based on which a prognostic model was constructed using LASSO regression. The mutations of the key hub genes were analyzed and their impacts on immunotherapy efficacy was predicted using the cBioPortal platform. RT-qPCR was used to verify the differential expressions of the key hub genes in Wilms tumor.

Results: Of the 1612 differentially expressed genes identified in Wilms tumor, 1030 were up-regulated and 582 were down-regulated, involving mainly cell cycle processes and immune responses. Ten hub genes were identified, among which 4 genes (TP53, MED1, CCNB1 and EGF) were closely related to the survival of children with Wilms tumor. A 3-gene prognostic signature was constructed through LASSO regression analysis, and the patients stratified into with high- and low-risk groups based on this signature had significantly different survival outcomes (HR=1.814, log-rank P=0.002). The AUCs of the 3-, 5- and 7-year survival ROC curves of this model were all greater than 0.7. The overall mutations in the key hub genes or the individual mutations in TP53/CCNB1 were strongly correlated with a lower survival rates, and a high TP53 expression was correlated with a poor immunotherapy efficacy. RT-qPCR confirmed that the key hub genes had significant differential expressions in Wilms tumor tissues and cells.

Conclusion: TP53 gene plays an important role in the Wilms tumor and may potentially serve as a new immunotherapeutic biomarker as well as a therapeutic target.

Objective: To construct a mutant strain of Klebsiella pneumoniae NTUH- K2044 with modA gene deletion and its complementary strain and explore the role of modA gene in modulating anaerobic nitrate respiratory growth and phenotypes of K. pneumoniae.

Methods: The modA deletion mutant K. pneumoniae strain was constructed by homologous recombination using the suicide vector pKO3-Km. To obtain the complementary strain C-modA, the whole sequence fragment containing the promoter, open reading frame and terminator regions of modA was cloned into pGEM-T-easy and electrically transformed into the modA deletion mutant. The NTUH-K2044 wild-type strain, modA gene deletion mutant and complementary strain were compared by measuring in vitro anaerobic nitrate respiration growth, competitiveness index, biofilm quantification, mucoviscosity assay and morphological measurement using Image J.

Results: The modA deletion mutant strain ΔmodA and the complementary strain C-modA were successfully constructed. The modA gene knockout strain showed inhibited anaerobic nitrate respiratory growth compared with the wild- type and C-modA strains with significantly weakened competitiveness, reduced capacity of biofilm synthesis during anaerobiosis, and lowered mucoviscosity under anaerobic conditions. The ΔmodA strain showed a spherical morphology in anaerobic conditions as compared with the normal short rod-like morphology of K. pneumoniae, with also distinctly shorter length than the wild-type and C-modA strains.

Conclusion: The molybdate transport system encoding gene modA is associated with the pathogenic capacity of K. pneumoniae by modulating its anaerobic nitrate respiration, competitiveness, biofilm formation, hypermucoviscous phenotype and morphology.

Objective: To explore the mechanism underlying the protective effect of α2-macroglobulin (A2M) against glucocorticoid-induced femoral head necrosis.

Methods: In a human umbilical vein endothelial cell (HUVEC) model with injuries induced by gradient concentrations of dexamethasone (DEX; 10^-8-10^-5 mol/L), the protective effects of A2M at 0.05 and 0.1 mg/mL were assessed by examining the changes in cell viability, migration, and capacity of angiogenesis using CCK-8 assay, Transwell and scratch healing assays and angiogenesis assay. The expressions of CD31 and VEGF-A proteins in the treated cells were detected using Western blotting. In BALB/c mouse models of avascular necrosis of the femoral head induced by intramuscular injections of methylprednisolone, the effects of intervention with A2M on femoral trabecular structure, histopathological characteristics, and CD31 expression were examined with Micro-CT, HE staining and immunohistochemical staining.

Results: In cultured HUVECs, DEX treatment significantly reduced cell viability, migration and angiogenic ability in a concentration- and time-dependent manner (P<0.05), and these changes were obviously reversed by treatment with A2M in positive correlation with A2M concentration (P<0.05). DEX significantly reduced the expression of CD31 and VEGF-A proteins in HUVECs, while treatment with A2M restored CD31 and VEGF-A expressions in the cells (P<0.05). The mouse models of femoral head necrosis showed obvious trabecular damages in the femoral head, where a large number of empty lacunae and hypertrophic fat cells could be seen and CD31 expression was significantly decreased (P<0.05). A2M treatment of the mouse models significantly improved trabecular damages, maintained normal bone tissue structures, and increased CD31 expression in the femoral head (P<0.05).

Conclusion: A2M promotes proliferation, migration, and angiogenesis of DEX-treated HUVECs and alleviates methylprednisolone-induced femoral head necrosis by improving microcirculation damages and maintaining microcirculation stability in the femoral head.

Objective: To explore the role of zinc finger protein 36(ZFP36) in regulating osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) and preosteoblasts.

Methods: ZFP36 expression was observed in primary mouse BMSCs and mouse preosteoblasts (MC3T3-E1 cells) during induced osteogenic differentiation. Zfp36-deficient cell models were constructed in the two cells using RNA interference technique and the changes in differentiation capacities of the transfected cells into osteoblasts were observed. Transcriptome sequencing was used to investigate the potential mechanisms of ZFP36 for regulating osteoblast differentiation of the two cells. U0126, a ERK/MAPK signal suppressor, was used to verify the regulatory mechanism of Zfp36 in osteogenic differentiation of Zfp36-deficient cells.

Results: During the 14-day induction of osteogenic differentiation, both mouse BMSCs and MC3T3-E1 cells exhibited increased expression of ZFP36, and its mRNA expression reached the peak level on Day 7(P < 0.0001). The Zfp36-deficient cell models showed reduced intensity of alkaline phosphatase (ALP) staining and alizarin red staining with significantly lowered expressions of the osteogenic marker genes including Alpl, Sp7, Bglap and Ibsp (P < 0.01). Transcriptome sequencing verified the reduction of bone mineralization-related gene expressions in Zfp36-deficient cells and indicated the involvement of ERK signaling in the potential regulatory mechanism of Zfp36. Immunoblotting showed that pERK protein expression increased significantly in Zfp36-deficient cells compared with the control cells. In Zfp36-deficient MC3T3-E1 cells, inhibition of activated ERK/MAPK signaling with U0126 resulted in obviously enhanced ALP staining and significantly increased expressions of osteoblast differentiation markers Runx2 and Bglap (P < 0.05).

Conclusions: ZFP36 is involved in the regulation of osteoblast differentiation of mouse BMSCs and preosteoblasts, and ZFP36 deficiency causes inhibition of osteoblast differentiation of the cells by activating the ERK/MAPK signaling pathway.

Objective: To investigate the prevalence of insomnia in college students and analyze the correlation between insomnia and perceived stress.

Methods: A cluster sampling method was used to investigate the prevalence of insomnia and stress levels in 3702 college students using Insomnia Severity Index (ISI) and Perceived Stress Scale-10 (PSS-10).

Results: Insomnia was detected in 31.4% of the college students, and the symptoms were more severe in male students (t=2.047, P=0.041) and in those with poorer family economic conditions (F=20.423, P<0.001). Insomnia was positively correlated with perceived stress, perceived distress, and perceived coping ability, with correlation coefficients of 0.42, 0.38, and 0.31, respectively (P<0.001). The students with higher levels of perceived stress had higher insomnia scores (F=203.03, P<0.001) and higher detection rate of insomnia (χ²=359.784, P<0.001), and those with moderate or severe insomnia also had higher levels of perceived stress (F=293.569, P<0.001). The types of perceived stress among college students included incontrollable (15.3%), nervous (8.3%), vulnerable (23.0%) and the relaxed types (53.5%). The incontrollable type was associated with the highest insomnia scores, followed by the nervous type and susceptible type, and the relaxed type had the lowest insomnia scores (F= 185.969, P<0.001). The prevalence rates of insomnia in students with the 4 types of perceived stress were 57.3%, 43.3%, 39.3%, and 18.7%, respectively (χ²=368.876, P<0.001).

Conclusion: There is a close correlation between perceived stress and insomnia, and identification of the high-risk population for insomnia from the perspectives of perceived stress level and perceived stress type can facilitate the management and prevention of insomnia.

Objective: To explore the therapeutic effect of transdermal patches containing Cassia seed extract applied at the navel on slow transit constipation (STC) in rats and explore the spectrum-effect relationship of the patches.

Method: In a STC rat model established by gavage of compound diphenoxylate suspension for 14 days, the transdermal patches containing low, medium and high doses of Cassia seed extract (41.75, 125.25, and 375.75 mg/kg, respectively) were applied at the Shenque acupoint on the abdomen for 14 days after modeling, with constipation patches (13.33 mg/kg) as the positive control. After the treatment, fecal water content and intestinal propulsion rate of the rats were calculated, the pathological changes in the colon were observed with HE staining. Serum NO and NOS levels and the total protein content and NO, NOS and AChE expressions in the colon tissue were determined. HPLC fingerprints of the transdermal patches were established, and the spectrum-effect relationship between the common peaks of the patches and its therapeutic effect were analyzed.

Results: Treatment with the transdermal patches containing Cassia seed extract significantly increased fecal water content and intestinal propulsion rate of the rat models, where no pathological changes in the colon tissue were detected. The treatment also suppressed the elevations of serum and colonic NO and NOS levels and reduction of AChE in STC rats. Twenty-eight common peaks were confirmed in the HPLC fingerprints of 6 batches of Cassia seed extract-containing patches. Analysis of the spectrum-effect relationship showed that autrantio-obtusin had the greatest contribution to the therapeutic effect of the patches in STC rats.

Conclusion: The Cassia seed extract-containing patches alleviates STC in rats via synergistic actions of multiple active ingredients in the extract, where autrantio-obtusin, rhein, chrysoobtusin, obtusin, obtusifolin, emodin, chrysophanol, and physcion are identified as the main active ingredients.

Objective: To investigate the expression level of Kruppel-like transcription factor family member KLF11 in intestinal mucosal tissues of Crohn's disease (CD) and its regulatory effect on intestinal inflammation in CD-like colitis.

Methods: We examined KLF11 expression levels in diseased and normal colon mucosal tissues from 12 CD patients and 12 patients with colorectal cancer using immunofluorescence staining. KLF11 expression was also detected in the colon mucosal tissues of a mouse model of 2, 4, 6-trinitrobenesulfonic acid (TNBS)-induced colitis. A recombinant adenoviral vector was used to upregulate KLF11 expression in the mouse models and the changes in intestinal inflammation was observed. A Caco-2 cell model with stable KLF11 overexpression was constructed by lentiviral infection. The effect of KLF11 overexpression on expressions of JAK2/STAT3 signaling pathway proteins was investigated using immunoblotting in both the mouse and cell models. The mouse models were treated with coumermycin A1, a JAK2/STAT3 signaling pathway agonist, and the changes in intestinal inflammatory responses were observed.

Results: The expression level of KLF11 was significantly lowered in both the clinical specimens of diseased colon mucosal tissues and the colon tissues of mice with TNBS-induced colitis (P < 0.05). Adenovirus-mediated upregulation of KLF11 significantly improved intestinal inflammation and reduced the expression levels of inflammatory factors in the intestinal mucosa of the colitis mouse models (P < 0.05). Overexpression of KLF11 significantly inhibited the expression levels of p-JAK2 and p-STAT3 in intestinal mucosal tissues of the mouse models and in Caco-2 cells (P < 0.05). Treatment with coumermycin A1 obviously inhibited the effect of KLF11 upregulation for improving colitis and significantly increased the expression levels of inflammatory factors in the intestinal mucosa of the mouse models (P < 0.05).

Conclusion: KLF11 is downregulated in the intestinal mucosa in CD, and upregulation of KLF11 can improve intestinal inflammation and reduce the production of inflammatory factors probably by inhibiting the JAK2/STAT3 signaling pathway.

Objective: To construct a nonparametric proportional hazards (PH) model for mixed informative interval-censored failure time data for predicting the risks in heart transplantation surgeries.

Methods: Based on the complexity of mixed informative interval-censored failure time data, we considered the interdependent relationship between failure time process and observation time process, constructed a nonparametric proportional hazards (PH) model to describe the nonlinear relationship between the risk factors and heart transplant surgery risks and proposed a two-step sieve estimation maximum likelihood algorithm. An estimation equation was established to estimate frailty variables using the observation process model. Ⅰ-spline and B-spline were used to approximate the unknown baseline hazard function and nonparametric function, respectively, to obtain the working likelihood function in the sieve space. The partial derivative of the model parameters was used to obtain the scoring equation. The maximum likelihood estimation of the parameters was obtained by solving the scoring equation, and a function curve of the impact of risk factors on the risk of heart transplantation surgery was drawn.

Results: Simulation experiment suggested that the estimated values obtained by the proposed method were consistent and asymptotically effective under various settings with good fitting effects. Analysis of heart transplant surgery data showed that the donor's age had a positive linear relationship with the surgical risk. The impact of the recipient's age at disease onset increased at first and then stabilized, but increased against at an older age. The donor-recipient age difference had a positive linear relationship with the surgical risk of heart transplantation.

Conclusion: The nonparametric PH model established in this study can be used for predicting the risks in heart transplantation surgery and exploring the functional relationship between the surgery risks and the risk factors.