Various brain-eating amoebae: the protozoa, the pathogenesis, and the disease / 医学前沿

Among various genera of free-living amoebae prevalent in nature, some members are identified as causative agents of human encephalitis, in which Naegleria fowleri followed by Acanthamoeba spp. and Balamuthia mandrillaris have been successively discovered. As the three dominant genera responsible for infections, Acanthamoeba and Balamuthia work as opportunistic pathogens of granulomatous amoebic encephalitis in immunocompetent and immunocompromised individuals, whereas Naegleria induces primary amoebic meningoencephalitis mostly in healthy children and young adults as a more violent and deadly disease. Due to the lack of typical symptoms and laboratory findings, all these amoebic encephalitic diseases are difficult to diagnose. Considering that subsequent therapies are also affected, all these brain infections cause significant mortality worldwide, with more than 90% of the cases being fatal. Along with global warming and population explosion, expanding areas of human and amoebae activity in some regions lead to increased contact, resulting in more serious infections and drawing increased public attention. In this review, we summarize the present information of these pathogenic free-living amoebae, including their phylogeny, classification, biology, and ecology. The mechanisms of pathogenesis, immunology, pathophysiology, clinical manifestations, epidemiology, diagnosis, and therapies are also discussed.

Study on tumor necrosis factor-α induced eryptosis / 国际生物医学工程杂志

Objective To investigate the role of tumor necrosis factor-α (TNF-α) on eryptosis.Methods Erythrocytes isolated from mice were put under the treatment of TNF-α at the dose of 1ng/ml for 6,12,24,48 and 72 h,or at different concentrations of 0.1,1 and 10 ng/ml for 24 h.The forward scatter (FSC),phosphatidylserine (PS)exposure and ceramide formation were determined by flow cytometry.Results Compared to control group,the decrease of FSC ((81.5 ± 1.02)％ vs (87.6 ± 0.55)％,P＜0.05),the increasment of membrane PS exposure level and ceramide content ((5.5±1.07)％ vs (2.7±0.17)％,(2.1±0.23)％ vs (0.7±0.26)％,P＜0.01) were observed in erythrocyte under the treatment of TNF-α for 24 h with more obvious tendency over time.Conclusions TNF-α can trigger cell shrinkage,and promote PS exposure and ceramide formation on the membrane of erythrocyte.

Phosphatidylserine exposure in red blood cell in sepsis patients / 国际生物医学工程杂志

Objective To investigate the morphologic change and phosphatidylserine (PS) exposure of erythrocytes in sepsis patients.Methods 30 healthy volunteers (control group)and 30 sepsis patients were enrolled in this study and were collected venous sampling.Monitoring included Wright's staining blood smear test,erythrocyte aggregation index and the ratio of PS exposure of erythrocytes.A flow-cytometric assay based on FITC-Annexin V was used to measure the PS exposure of erythrocytes.Results The morphological changes of red blood cells included acanthocyte,lachrymiform,rouleaux,spherocyte in sepsis patients,and the peripheral blood erythrocyte aggregation and aggregation index were significantly higher than that of the healthy control group (P＜0.05).The percentage of PS exposure of erythrocytes in sepsis patients were significantly higher than that of healthy volunteers (P＜0.001).Conclusion The PS exposure of erythrocytes were significantly higher in sepsis patients,and the morphology of red blood cells is obvious abnormal.