单细胞真菌多糖对绿脓杆菌在小鼠肠道定植与转移的影响

选择粪便中绿脓杆菌(P.aeruginosa)数10~4/g的小鼠,经抗生素及抗生素加MFPS处理后,通过无菌饮水接种P.aeruginosa,定期测定粪便中该菌的数量。结果表明,MFPS可以有效地阻止由于抗生素对肠道菌群生态平衡的破坏而致的P.aeruginosa的定植及过度生长。即使在环磷酰胺诱发下,P.aeruginosa的转移也只发生在少数鼠(30％)的个别器官,也没有小鼠死亡。未有MFPS保护、经抗生素处理的全部小鼠的主要脏器(心、肺、肝、肾及脾)均由于该菌的转移而被感染,并有37.5％小鼠死亡。     

Identification of a chloroplast-encoded secA gene homologue in a chromophytic alga: possible role in chloroplast protein translocation

Summary SecA is one of seven Sec proteins that comprise the prokaryotic protein translocation apparatus. A chloroplast-encoded secA gene has been identified from the unicellular chromophytic alga Pavlova lutherii. The gene predicts a protein that is related to the SecA proteins of Escherichia coli and Bacillus subtilis. The presence of secA, as well as the previously described secY and hsp70 genes, on the chloroplast genome of P. lutherii suggests that this eukaryotic organism utilises protein translocation mechanisms similar to those of bacterial cells.     

Detection of bacterial translocation during intestinal distension in rats using the polymerase chain reaction

To investigate whether distension causes bacterial translocation (BT), a rat model reported earlier by us was used and to detect the presence of bacterial DNA in blood by polymerase chain reaction (PCR) assay, the most sensitive detection method to date. In 4 groups of 4-week-old Wistar-albino rats a total of 15 animals each were included. In the 1st group (distension+gavage), 10¹⁰ Escherichia coli colonies were given via gavage and distension was carried out by rectal air inoculation. In the 2nd group (gavage), animals were inoculated with E. coli and no distension was induced. The 3rd group (distension) were only distended and no bacteria were inoculated. The control group were neither distended nor inoculated with E. coli. Blood samples were collected 3 h after manipulations and both blood cultures and PCR assays were performed. According to the PCR results BT was evident in 80% of group 1, 20% of group 2, and 33% of group 3 animals. BT was not determined in the control group. Significantly low percentages of positivity were observed in blood cultures in all groups (P < 0.05). These results confirm reports that BT occurs in the presence of distension and that PCR is a superior way of determining BT. Thus, it would be advisable to utilize PCR technology in cases where the possibility of distension exists, as early intervention might be useful before any severe clinical pathology (sepsis, multiple-organ-system failure) becomes evident. Accepted: 19 December 2000     

Size effect on systemic and mucosal immune responses induced by oral administration of biodegradable microspheres

Induction of systemic and mucosal immune responses following oral administration of biodegradable poly( -lactic acid) (PDLLA) microspheres containing a model antigen, ovalbumin (OVA) was studied using microspheres with different average diameters of 0.6, 1.0, 4.0, 7.0, 11.0, 15.0, 21.0, and 26.0 μm. They were prepared from double emulsion with the solvent evaporation method, followed by size fractionation on counterflow elutriation. OVA was released from the microspheres in vitro over 80 days, irrespective of their size. Production of the serum anti-OVA IgG antibody and secretory OVA-specific IgA antibody in the mice gut was assessed following the oral administration of PDLLA microspheres containing OVA. Microspheres with a diameter of 4.0 μm enhanced the serum antibody in contrast with that of free OVA, but were not effective in inducing the gut secretion of IgA antibody. On the other hand, OVA-containing microspheres with a diameter of 7.0 μm enhanced IgA secretion to a significant extent compared with free OVA, whereas those with 26.0 μm in diameter were ineffective. Body distribution study revealed that the amount of microspheres taken up into Peyer's patches (PP) increased with the increasing size up to 11.0 μm, thereafter decreased, and finally became zero when their diameters were 21.0 μm or larger. The microspheres taken up into PP were translocated to the spleen, but no microspheres were noticed in the spleen when the size was larger than 5 μm. After being taken up into PP, microspheres <5 μm in diameter seemed to be transported to the spleen, a systemic lymphoid tissue, where the released antigen stimulated a serum antibody response, but larger microspheres probably remained at PP without being tanslocated to the spleen over the course of their antigen release, leading to induction of IgA secretion. It was concluded that the body distribution pattern of microspheres following the PP uptake was a key factor to regulate the induction of systemic and mucosal immune responses.     

肱骨骨折行桡神经内侧转位的临床应用

1996—2004年我院对36例肱骨中下段骨折手术内固定的同时，行桡神经内侧转位术，为再次手术提供方便和避免神经损伤，效果满意，现报告如下。     

In utero origins of childhood leukaemia

Chimaeric fusion genes derived by chromosome translocation are common molecular abnormalities in paediatric leukaemia and provide unique markers for the malignant clone. They have been especially informative in studies with twins concordant for leukaemia and in retrospective scrutiny of archived neonatal blood spots. These data have indicated that, in paediatric leukaemia, the majority of chromosome translocations arise in utero during foetal haemopoiesis. Chromosomal translocations and preleukaemic clones arise at a substantially higher frequency ( approximately 100x) before birth than the cumulative incidence or risk of disease, reflecting the requirement for complementary and secondary genetic events that occur postnatally. A consequence of the latter is a very variable and occasionally protracted postnatal latency of disease (1-15 years). These natural histories provide an important framework for consideration of key aetiological events in paediatric leukaemia.     

The effects of ketamine and propofol on bacterial translocation in rats after burn injury

BACKGROUND: Bacterial translocation (BT) occurs after thermal injury and may result from an ischemic intestinal insult. The aim of the study was to investigate the effects of ketamine and propofol as anesthetic agents on BT in an animal model of burn injury. METHODS: Sixty male Wistar Albino rats were randomly assigned to six groups of 10 rats each. Anesthesia was induced and maintained with ketamine in groups 1, 2 and 3 and with propofol in groups 4, 5 and 6 during 6 h. Groups 2, 3, 5 and 6 received 30% total body surface area (TBSA) third-degree burns. Groups 1 and 4 had no burn injury. Then, they were allowed to recover from the anesthesia at the end of 6 h. Mean arterial pressure (MAP) was monitored continuously and maintained within 10% of baseline (before burn injury) levels in all animals. Animals in groups 3 and 6 had a laparotomy to obtain a tissue sample from the terminal ileum for determination of intestinal lipid peroxidation by-product malondialdehyde (MDA) before (baseline) and 6 and 24 h after burn injury (ABI). So these animals were not included in the BT studies. At postburn 24 h, animals in groups 1, 2 and 4, 5 were sacrified and samples were taken from the mesenteric lymph nodes (MLN), liver and spleen for bacteriologic cultures. RESULTS: The incidence of BT was found to be significantly higher in group 2 than in all the other groups. Bacterial translocation incidence of group 5 was not significantly different from that of groups 4 and 1. Group 5 was associated with a significantly reduced number of enteric organisms per gram of tissue compared to group 2. Baseline MDA contents of groups 3 and 6 were similar. Ileal MDA levels were increased in group 3, but there were no significant changes in group 6 at 6 and 24 h ABI compared to baseline. CONCLUSION: Our results suggest that propofol as an anesthetic agent may prevent BT by scavenging reactive oxygen species and inhibiting lipid peroxidation in an animal model of burn injury.