Biomedical subjects

Hong-Jun Yang

Publications and source records attributed to Hong-Jun Yang.

6 recordsLinked to original sources

PubMed2006

[High-level production of neutral endoglucanase 1 in Pichia pastoris].

The gene (eg1) encoding for novel endoglucanase 1 was cloned previously from Chinese straw mushroom Volvariella volvacea. EG1 has high thermal stability and optimal pH at neutral and shows great potential in textile and paper industry applications. To improve the expression level of EG1 in Pichia pastoris, the increasing copy number of clone, and its high cell density fermentation in 3.2L fermenter for its high-level expression were investigated in this work. By electro-transformation of pPICZalphaB-egl into GS115EG11 integrated with single copy of eg1 gene, A resistant transformant with 3.8 times higher level expression than GS115EG11 was screened from YPDSZ plate containing 2000 microg/mL of Zeocin. The effect of initial cell density, pH and methanol on its expression and biomass accumulation was evaluated in shaking culture. Optimal EG1 production was observed when initial cell density OD600 was 5.0. EG1 production and biomass accumulation did not seem to vary when cells were induced at different pH values. Both of EG1 and cell density were found to increase with higher methanol concentrations, reaching 62.48 IU/mL and 31.7 (OD600) respectively after 120 h induction with 2.0% (V/V) methanol compared to 30.24 IU/mL and 17.79 (OD60) with 0.25% methanol induction. EG1 expression was further increased by 6.4 times higher than shaking culture after 95.5 hours induction with methanol in fed-batch fermentation, so totally 34 times higher than that for GS115EG11 was achieved by screening of high Zeocin resistant clone and high cell density fermentation. The production of EG1 with 543.36IU/mL CMC activity and 8.80mg/mL protein expression was obtained in Pichia pastoris.

Cellulase↗

PubMed2006

[Spontaneous discharge modulation by acetylcholine in chronically compressed rat dorsal root ganglion neurons].

OBJECTIVE: To study the effects of acetylcholine (ACh) on spontaneous discharges of compressed rat dorsal root ganglion (DRG) neurons. METHODS: In chronically compressed DRG model, the spontaneous discharge of a single fiber from the DRG neuron in response to ACh treatment was recorded. RESULTS: Active spontaneous discharges were recorded in the injured DRG, and 77.9% of the injured DRG neurons responded to Ach treatment in the manner of simple excitation, or excitation followed by inhibition. The responses were enhanced with the increase of Ach concentration. CONCLUSION: Injured DRG remains active in spontaneous discharges, which can be significantly influenced by ACh treatment.

Acetylcholine↗

PubMed2005

[Protective effect of the pretreatment with Chuanxiong-phthalide A on the vascular endothelial cells impaired by the ischemia and reperfusion in isolated rats hearts].

OBJECTIVE: The aim of this study was to investigate the protective effect of Chuanxiong-pathalide A on the injury of endothelial cell induced by ischemia and reperfusion in isolated rat hearts. METHOD: The isolated rat hearts were perfused under constant pressure with Chuanxiong-pathalide A at the concentrations of 0.012 5 mg x mL(-1), 0.025 mg x mL(-1) and 0.05 mg x mL(-1) within 10 min followed by a 10-min washout period before the induction of a 30-min normothermic global ischemia and 60 min reperfusion. RESULT: Pretreatment with Chuanxiong-pathalide A produced a reduction in the incidence of reperfusion-induced ventricular fibrillation (VF) and ventricular tachycardia (VT). Pretreatment of the hearts with high dose of Chuanxiong-pathalide A (0.05 mg x mL(-1)) prior to the ischemia and reperfusion, reduced the incidence of reperfusion-induced VF and VT to 37.5% as compared with non-pretreated control group (P < 0.05). The duration of occurrence of VF and VT in the group pretreated with Chuanxiong-pathalide A at dosages of 0.012 5 mg x mL(-1), 0.025 mg x mL(-1) and 0.05 mg x mL(-1) were (7.50 +/- 1.61), (1.64 +/- 0.67) and (1.06 +/- 0.70) min respectively, which were significantly shorter than (23.51 +/- 3.99) min in non-pretreated control group; 0.05 mg x mL(-1) of Chuanxiong-pathalide A increased coronary flow in comparison with the control group. The content of SOD in the group pretreated with 0.05 mg x mL(-1) of Chuanxiong-pathalide A was (59.6 +/- 18.7) U x mg(-1), significant lower than (92.3 +/- 19.0) U x mg(-1) in the non-pretreated group. The contents of LDH and MDA were (2 378.0 +/- 196.3) U x g(-1) and (12.1 +/- 1.3) nmol x mg(-1) in the non-pretreated group, which were much higher than the values of (1 669.4 +/- 192.5) U x g(-1) and (6.9 +/- 0.8) nmol x mg(-1) in the group pretreated with Chuanxiong-pathalide A respectively. In addition, enzymeimmunoassays showed an decreased production of IL-1beta and the ratio of TXB2/6-Keto-PGF1alpha. CONCLUSION: Our results show that chuanxiong-pathalide A pretreatment can protect the endothelial function from the injury caused by ischemia and reperfusion.

Animals↗

PubMed2004

A universal microarray for detection of SARS coronavirus.

Severe acute respiratory syndrome (SARS) is caused by the SARS coronavirus (SARS-CoV). There are many point mutations among SARS-CoV genome sequences. Previous studies suggested that the mutations are correlated closely with the SARS epidemic. It was found that the bases of six nucleotide positions (nt9404, nt9479, nt19838, nt21721, nt22222 and nt27827) with high-mutation rate have an important relationship with the SARS epidemic. For viral detection as well as genotyping, a universal microarray system was developed that combines RT-PCR and ligase detection reaction (LDR). The Zip Codes attached covalently to a slide remain constant and their complementary Zip Codes (cZip Codes) can be used for tagging target sequence, making the microarrays universal. The discriminating oligonucleotides contain on the 5' end "cZip Codes" that are used to direct LDR product to specific Zip Codes attached covalently to a slide. Since Zip Codes have no homology to either the target sequence or to other sequences in the genomes of both human host and SARS-CoV, there was no false signal due to mismatch hybridizations. 20 samples assayed with the universal microarray were confirmed by DNA sequencing, demonstrating that this microarray system is a promising diagnostic tool for detection and genotyping of the SARS-CoV.

Amino Acid Substitution↗

PubMed2002

Relation between responsiveness to neurotransmitters and complexity of epileptiform activity in rat hippocampal CA1 neurons.

PURPOSE: Our previous works suggested that sensitivity of neurons with chaotic firing patterns to stimuli is significantly greater than that in neurons with periodic firing patterns, which shows that responsiveness of neurons may depend on the complexity of the firing series. This study was performed to determine the relation between responsiveness of the hippocampal CA1 neurons with epileptiform activity (EA) to neurotransmitters and their complexity of firing series. METHODS: Firing series of CA1 neurons were recorded extracellularly in rat hippocampal slice. Approximate entropy was used to describe the complexity of the interspike interval (ISI) series. EA was induced by local application of penicillin (1,000 IU/ml). The change of firing rate induced by neurotransmitters (glutamate and gamma-aminobutyric acid) was compared with that of the degree of complexity of ISI series in the process of EA. RESULTS: The excitatory responses to glutamate and the inhibitory responses to gamma-aminobutyric acid in CA1 neurons appeared to be decreased during the process of penicillin-induced EA. However, during this same process, the approximate entropy of the ISI series also was decreased significantly. CONCLUSIONS: The results suggest that the reduced responses to neurotransmitters of the CA1 neurons appear to be closely related to the onset of EA. Furthermore, these neurons show that the changes in responsiveness are closely parallel to the decrease of degree of complexity of firing series during penicillin epileptogenesis.

Action Potentials↗

PubMed2002

[Seizure inhibition by vagal nerve stimulation in rats].

OBJECTIVE: To study the effect of vagal nerve stimulation in seizure inhibition in rats. METHODS: In rat epileptic models induced by penicillin, electromyogram (EMG), electroencephalogram (EEG) and extracellular electric activity of the cortex were recorded to study the inhibiting effect of vagal nerve stimulation on epilepsy. Results Inhibiting effect of vagal nerve stimulation on epilepsy was observed from the changes in behavior, EMG, EEG and extracellular electric activity of the rats, and this inhibiting effect was enhanced as the frequency for stimulation increased from 5 Hz to 20 Hz. Conclusion Vagal nerve stimulation can inhibit the epileptic activity in rats, the effect of which depends on the stimulation conditions imposed on the rats.

Animals↗