Decreased cyclic-AMP caused by ATP contributes to fosfomycin heteroresistance in avian Escherichia coli.

BACKGROUND: Fosfomycin is an important broad-spectrum bactericidal antibiotic to treat multidrug-resistant bacteria infections. It is generally accepted that heteroresistant bacteria are an intermediate stage in the formation of drug resistance, but there are few studies on the formation mechanism underlying fosfomycin heteroresistance (FHR). OBJECTIVES: To reveal the characteristics and formation mechanisms of FHR in Escherichia coli isolates obtained from chickens. METHODS: We identified the FHR according to the population analysis profile (PAP) test and in vitro time-kill assay. Growth curves for FHR E. coli and their subpopulations were measured. Also, the subpopulations were repeatedly cultured in fosfomycin-free medium for 5-20 overnight incubation periods. The formation mechanisms of FHR in E. coli isolates were identified through accumulation assay, carbohydrate utilization testing, real-time relative quantitative PCR analysis, DNA sequencing, transcriptomic analysis, intracellular ATP and cAMP-level assessment. RESULTS: Four of six E. coli strains were confirmed to show FHR, with a total of six subpopulations. The subpopulations restored phenotypic susceptibilities to fosfomycin within 5-20 overnight incubation sessions, but four of six subpopulations still maintained FHR characteristics. Differing from their parental isolates, the uptake of fosfomycin in the subpopulations through GlpT was reduced remarkably. Further studies identified that the low expression of glpT was due to the decrease of intracellular cAMP levels in the subpopulations, which was caused by the decreased ATP levels in cells. CONCLUSIONS: Our findings revealed the formation mechanism of E. coli isolates showing FHR obtained from chicken in China and characterized the dynamic change traits in vitro of the subpopulations.

[Electroacupuncture improved learning-memory ability by reducing hippocampal apoptosis and suppressing JNK signaling in rats with vascular dementia].

OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation on the expression of c-Jun terminal kinase(JNK)signaling pathway-related proteins in the hippocampus of vascular dementia (VD) rats, so as to explore its mechanisms underlying improvement of VD. METHODS: Male Sprague-Dawley rats were randomly divided into sham operation, model and EA groups (n＝10 rats per group). The VD model was prepared by repeated occlusion of the bilateral common carotid arteries for 10 min and reperfusion for 10 min (3 times in total). The rats in the EA group received EA (2 Hz, 2 mA) at "Dazhui"(GV14)，"Baihui"(GV20), and bilateral "Housanli"(ST36) ，"Geshu"(BL17) for 10 min, once daily for 14 days. The learning-memory abi-lity was detected by Morris water maze tests, the distribution of hippocampal neurons detected by Nissl staining, and the apoptosis of hippocampal neurons detected by using TdT-mediated dUTP nick-end labeling (TUNEL) method. The expressions of JNK, phosphorylated JNK (p-JNK), cysteine-containing aspartate-specific proteases-8 (Caspase-8) and Caspase-3 proteins were detected by Western blot. RESULTS: After modeling and compared with the sham operation group, the escape latency was significantly prolonged (P<0.01) and the number of safe-platform quadrant crossing obviously decreased (P<0.01), suggesting a reduction of learning-memory ability. The number of hippocampal neurons was considerably reduced (P<0.01), and that of hippocampal apoptotic neurons remarkably increased in the model group (P<0.01). Whereas, the expression levels of hippocampal apoptosis-related proteins as JNK, p-JNK, Caspase-8 and Caspase-3, as well as the apoptotic index were significantly up-regulated (P<0.01). Following EA intervention, the learning-memory ability was apparently improved (P<0.01), and the number of hippocampal neurons was considerably increased (P<0.01), the hippocampal apoptotic cell number, apoptosis index and the expression levels of JNK, p-JNK, Caspase-8 and Caspase-3 were significantly down-regulated (P<0.01). CONCLUSION: EA intervention can improve the learning-memory ability of VD rats, which may be associated with its effects in reducing hippocampal apoptosis by suppressing JNK signaling pathway.

[Effect of mild moxibustion on macrophage number and collagen expression of raw surface tissue in chronic refractory skin ulcer rats].

OBJECTIVE: To observe the effect of mild moxibustion on the number of macrophages and contents of collagen I and III in the raw surface tissue in chronic skin ulcer rats so as to study its mechanism underlying promoting scar formation. METHODS: Eighty male SD rats were randomly divided into normal (n = 8), model (n = 24), TDP (n = 24) and moxibustion (n = 24) groups. Chronic refractory skin ulcer was established by making an open wound at the back and local intramuscular injection of hydrocortisone sodium succinate. For rats of the TDP and moxibustion groups, TDP irradiation or mild moxibustion was applied to the raw surface, bilateral "Shenshu" (BL 23) and "Zusanli" (ST 36) for 15 min, once daily for 7, 10 and 14 days, respectively. The number of macrophages in the raw surface tissue was counted under light microscope after H. E. staining and col- lagen I and III expressions of the raw surface tissue were detected by immunohistochemistry. RESULTS: In comparison with the normal group, the numbers of macrophages in the raw surface tissue were increased significantly in the model group on day 7, 10 and 14 (P < 0.05); while compared with the model group, the numbers of macrophages were increased further obviously in the moxibustion group on day 7 and 10 and in the TDP group on day 10 after the treatment (P < 0.05). Compared with the model group, the numbers of macrophages in both TDP and moxibustion groups were down-regulated obviously (P < 0. 05). In regard to collagen I and III expression of the raw surface tissue, compared with the normal group, the collagen I protein expression level was down-regulated markedly in the model group on the 7th day (P < 0.01); whereas in comparison with the model group, the expression levels of collagen I and III were increased considerably in the TDP and moxibustion groups on day 7 and 14 after the treatment (P < 0.05, P < 0.01). The ratios of collagen I/III expression were remarkably higher in the model group than in the normal group on day 7 and 14 (P < 0.05), and significantly lower in the TDP group on day 7 and 14 and in the moxibustion group on day 14 than in the model group (P < 0.05, P < 0.01). The effects of moxibustion were obviously superior to those of TDP in up-regulating macrophage number on day 10, up-regulating collagen I and III expressions on day 14, and down-regulating macrophage number on day 14 after the treatment (P < 0.05, P < 0.01). No significant differences were found between the TDP and moxibustion groups in up-regulating macrophage number, and collagen I and III protein expressions, and in down-regulating the ratios of collagen I/III expression on day 7 after the treatment (P > 0.05). CONCLUSION: Mild moxibustion can regulate the number of macrophages and strengthen the expression of collagen proteins in the raw surface tissue in the chronic skin ulcer rats, which may contribute to its effect in promoting wound healing and reducing scar formation.

[Effect of mild-warm moxibustion on microcirculation in the raw surface tissue of chronic refractory wound in skin ulcer rats].

OBJECTIVE: To observe the effects of mild-warm moxibustion on dynamic blood flow, microvessel count (MVC)and vascular endothelial growth factor (VEGF) expression in the wound tissue of the chronic skin ulcer in rats, so as to reveal its underlying mechanism in promoting wound recovery. METHODS: A total of 104 male SD rats with skin injury were randomly divided into control group (n=8), model group (n=32), TDP (far-infrared heating device) group (n=32) and moxibustion group (n=32). Chronic refractory raw surface wound model was established by muscular injection of Hydrocortisone Sodium Succinate. For rats of the TDP and moxibustion groups, TDP irridiation and mild-warm moxibustion were applied to the raw surface, bilateral "Shenshu" (BL 23) and "Zusanli" (ST 36) for 15 min, once daily for 3, 7 and 14 days respectively. The healing rate and the healing time of raw surface of the wound were observed. The blood flow of the raw surface of the wound tissue was measured by laser Doppler flowmeter and the MVC in granulation tissue of chronic skin ulcer was counted under light microscope. VEGF expression was detected by immunohistochemistry. RESULTS: In comparison with the control group, the healing rate of the wound raw surface was significantly lower and the healing time was prolonged in the model group (P < 0.01). Compared with the model group, the healing rates on day 3, 7, 10 and 14 were significantly higher and the healing time was strikingly faster in both TDP and moxibustion groups (P < 0.01, P < 0.05), and the effects of the moxibustion group in increasing the healing rate and shortening the healing time were significantly better than those of TDP group (P < 0.01). In comparison with the model group, the blood flow volume, MVC and VEGF expression levels on day 3 and 7 were upregulated significantly in both TDP and moxibustion groups (P < 0.01, P < 0.05); while the blood flow volume, MVC and VEGF expression level in the moxibustion group and the blood flow volume and VEGF expression level in the TDP group downregulated considerably on day 14 (P < 0.01). No significant difference was found between the TDP and moxibustion groups in the MVC on day 14 after the treatment (P > 0.05). CONCLUSION: Mild-warm moxibustion can promote wound healing, which is closely with its effects in increasing blood flow and MVC, and upregulating VEGF expression in the wound granulation tissue of the chronic skin ulcer.