Biomedical subjects

Yancheng Liu

Publications and source records attributed to Yancheng Liu.

5 recordsLinked to original sources

PubMed2006

The Legionella pneumophila effector SidJ is required for efficient recruitment of endoplasmic reticulum proteins to the bacterial phagosome.

The virulence of Legionella pneumophila is dependent on the Dot/Icm type IV protein secretion system, which translocates effectors into infected cells. A large number of such translocated proteins have been identified, but few of these proteins are necessary for intracellular replication of the pathogen, making it difficult to correlate these genes with specific cell-biological events associated with L. pneumophila infection. We report here the identification and characterization of a family of two substrates, SidJ and SdjA, with distinctive phenotypes. In contrast to many Dot/Icm substrates, whose expression levels are elevated when bacteria are grown to postexponential phase, SidJ is produced at a constant rate during the entire bacterial growth cycle. Mutation in sidJ causes a significant growth defect in both macrophage and amoeba hosts, but an sdjA mutant is detectably defective only in protozoan hosts. However, in the amoeba host a mutant lacking both sidJ and sdjA does not display a more severe growth defect than the sidJ mutant. Despite its significant intracellular growth defect, the sidJ mutant is still able to effectively evade fusion with lysosomes. Importantly, recruitment of endoplasmic reticulum (ER) proteins by vacuoles containing the sidJ mutant was considerably delayed in both mammalian and amoeba cells. Our results suggest that SidJ modulates host cellular pathways, contributing to the trafficking or retention of ER-derived vesicles to L. pneumophila vacuoles.

Animals↗

PubMed2006

Influence factors for functional improvement after olfactory ensheathing cell transplantation for chronic spinal cord injury.

OBJECTIVE: To explore the influence factors for the functional improvement after the fetal olfactory ensheathing cell (OEC) transplantation for chronic spinal cord injury(SCI). METHODS: The olfactory bulbs were harvested and trypsinized down to single fetal OEC. They were cultured for 12-17 days prepared for use. From November 2001 to December 2003, a total of 300 patients volunteered for the fetal OEC transplantation, among whom 222 suffered from complete chronic SCI and 78 suffered from incomplete chronic SCI. The procedures were performed on the patients with a disease course ranging from 6 months to 31 years (average 3.1 years) after their injuries. The fetal OEC was transplanted by the form of injections into the spinal cord at the upper and lower ends of the injury site. All the patients were assessed by the ASIA standard before the transplantation and 2-8 weeks after the transplantation. The influence factors including age, sex, duration after the injury, and injury degrees and levels were compared with those in the functional improvement after fetal OEC transplantation. RESULTS: The partially-improved neurological functions assessed by the ASIA standard were indicated by the motor scores increasing from 39.1 +/- 20.6 to 45.9 +/- 20.3 (P < 0.001), the light touch scores from 51.7 +/- 24.9 to 63.4 +/- 23.0 (P < 0.001), and the pin prick scores from 53.0 +/- 24.2 to 65.3 +/- 22.7 (P < 0.001). There was no significant difference in the functional improvement of the motor, light touch, and pin brick when compared with the age, sex, duration after the injury, and the injury degrees and levels. The motor scores and light touch scores at the cervical level were higher than the scores at the thoracic level. CONCLUSION: The fetal OEC transplantation can partially improve the neurological functions quickly in treatment of the chronic spinal cord injury. All the influence factors except the motor scores and light touch scores, which were higher at the cervical level than at thoracic level, have no impact on the functional improvement after the fetal OEC transplantation.

Adolescent↗

PubMed2006

Safety of fetal olfactory ensheathing cell transplantation in patients with chronic spinal cord injury. A 38-month follow-up with MRI.

OBJECTIVE: To determine the safety of the fetal olfactory ensheathing cell (OEC) transplantation in patients with chronic spinal cord injury (SCI) by examination of the magnetic resonance imaging (MRI). METHODS: A prospective clinical study involving 16 patients with chronic SCI was designed to investigate the feasibility and biological safety of the fetal OEC transplantation in treatment of SCI. The olfactory bulbs from the 3-4-month-old aborted human fetuses following the strict ethical guidelines were harvested and trypsinized down to single fetal OEC. These cells were then cultured for 12-17 days and were prepared for a clinical use. From November 2001 to December 2002, 16 patients with chronic SCI were randomly enrolled. The patients suffered from SCI for 1.5-8 years (average 4.3 years) after the injury. The suspension (50 microl) containing about 1 x 10(6) fetal OECs was transplanted by an injection into the patients' spinal cords above and below the injury site. All the patients were assessed before the transplantation and were followed up with MRI for 29-42 months (average 38 mon) after the transplantation. RESULTS: No cell-related adverse effects were observed in any patient during the follow-up period. The follow-up with MRI did not reveal any development of optic glial tumor, tumor-like mass, new hemorrhage, edema, expanding cyst, new cyst formation, infection or disruption of the neural structure in the transplant site of all the patients. CONCLUSION: This is the first clinical study demonstrating the long-term safety of the OEC therapy for SCI. The results indicate that our protocol is feasible and safe in treatment of patients with chronic SCI within 38 months after the injury. Although the size of the samples for our study was not big enough, the positive results of the study have encouraged us to make a further research in this field.

Adult↗

PubMed2005

Effect of glutathione on UV induction of prophage lambda.

The effect of glutathione (GSH) on the ultraviolet (UV) induction of lambda prophage was investigated in lysogenic Escherichia coli. The data showed that extracellular GSH could inhibit the UV induction of lambda prophage. The inhibitory rates were concentration dependent, and the maximal rate obtained was 94% with 3.0 M GSH. The effect was also measured in three different lambda lysogens: a wild-type strain (wt), an isogenic GSH-deficient strain, and an isogenic strain producing increased amounts of GSH. The result showed that when subjected to UV irradiation (254 nm, 60 J m(-2)), GSH-deficient strain was approximately fivefold more sensitive to be lysed than wt, whereas the strain with higher intracellular GSH levels was only 28% susceptible to be lysed. With electron spin resonance and spin trapping techniques, we observed that free radical signals occurred in the suspensions of UV irradiated lysogenic cells and the intensity of signals was influenced by GSH levels. These results indicate that GSH can significantly inhibit the UV induction of lambda prophage, and that this effect is correlated to its capacity to scavenge free radicals generated after UV irradiation.

Bacteriophage lambda↗

PubMed2005

EEG activities in the orbitofrontal cortex and dorsolateral prefrontal cortex during the development of morphine dependence, tolerance and withdrawal in rhesus monkeys.

Investigating the activities of the prefrontal cortex (PFC) in the process of addiction is valuable for understanding the neural mechanism underlying the impairments of the PFC after drug abuse. However, limited data are obtained from primate animals and few studies analyze Electroencephalogram (EEG) in the gamma band, which plays an important role in cognitive functions. In addition, it is yet unclear whether drug abuse affects the orbitofrontal cortex (OFC) and dorsolateral PFC (DLPFC)--the two most important subregions of the PFC--in similar ways or not. The aim of this study is to address these issues. We recorded EEG in the OFC and DLPFC in three rhesus monkeys. All animals received a course of saline (NaCl 0.9%, 2 ml) injection (5 days) followed by 10 days of morphine injection (every 12 h), and then a further series of saline injection (7 days). A main finding in the present study was that morphine decreased EEG power in all frequency bands in a short period after injection in both the OFC and DLPFC in monkeys. And gamma power decreased not just in a short period after morphine injection but lasted to 12 h after injection. Moreover, we found that although the changes in EEG activities in the OFC and DLPFC at 30-35 min after injection were similar, the DLPFC was more sensitive to the effect of morphine than the OFC.

Analysis of Variance↗