Objective:To explore the protective mechanisms of nerve growth factor (NGF) on spinal cord injury (SCI) and provide theoretical basis for its clinical application. Methods: The SCI of Wistar rats was done by Allens w...Objective:To explore the protective mechanisms of nerve growth factor (NGF) on spinal cord injury (SCI) and provide theoretical basis for its clinical application. Methods: The SCI of Wistar rats was done by Allens weight dropping way by a 10 g×2.5 cm impact on the posterior of spinal cord T 8. NGF (3 g/L, 20 μl) or normal saline was injected through catheter into subarachnoid space 2, 4, 8, 12 and 24 h after SCI. The expression of N-methyl-D-asparate receptor 1 (NMDAR 1) and neuronal constitutive nitric oxide synthase (ncNOS) mRNA in rat spinal cord was detected by in situ hybridization. Results: Abnormal expression of NMDAR 1 and ncNOS mRNA appeared in spinal ventral horn motorneuron in injured rats, as compared with that in control group. The expression of NMDAR 1 and ncNOS mRNA in NGF group was significantly lower than that in saline group (P<0.01). Conclusion: NGF can protect spinal cord against injury in vivo. One of the mechanisms is that NGF can prohibit NMDAR 1 and nitric oxide (NO) production after spinal cord injury.展开更多
AIM: To develop a PCR assay using mutant-specific primers to detect mutation of tyrosine-methionine-aspartate-aspartate (YMDD) motif of HBV to tyrosine-valine-aspartate-aspartate (YVDD) or tyrosine-isoleucine-aspartat...AIM: To develop a PCR assay using mutant-specific primers to detect mutation of tyrosine-methionine-aspartate-aspartate (YMDD) motif of HBV to tyrosine-valine-aspartate-aspartate (YVDD) or tyrosine-isoleucine-aspartate-aspartate (YIDD).METHODS: Cloned wild-type and mutant HBV sequences were used as templates to test the sensitivity and specificity of the assay. A variety of primer construction, primer concentration, dNTP concentration, and annealing temperature of primers were systematically examined. Pair primers specifi c to rtL180M and rtM204V were selected for YVDD detection. Primer specif ic to rtM204I with an additional 3’-penultimate base mismatched to both the mutant and wild-type sequence was selected for YIDD detection. We applied this assay to study YMDD mutants in 28 chronic hepatitis B patients before and after lamivudine treatment.RESULTS: We could detect as little as 0.001%-0.00001% of mutant viruses coexisting in 108-109 copies of wild-type HBV using this assay. YMDD mutants were detected in 8 of 12 HBeAg-positive patients and 8 of 16 HBeAg-negative patients before lamivudine treatment. After treatment, two more patients in HBeAg-positive patients and seven more patients in HBeAg-negative patients developed YMDD mutations. CONCLUSION: We developed a highly sensitive and specifi c assay for detecting YMDD mutants. This assay can be applied to monitor chronic hepatitis B patients before and during lamivudine treatment.展开更多
文摘Objective:To explore the protective mechanisms of nerve growth factor (NGF) on spinal cord injury (SCI) and provide theoretical basis for its clinical application. Methods: The SCI of Wistar rats was done by Allens weight dropping way by a 10 g×2.5 cm impact on the posterior of spinal cord T 8. NGF (3 g/L, 20 μl) or normal saline was injected through catheter into subarachnoid space 2, 4, 8, 12 and 24 h after SCI. The expression of N-methyl-D-asparate receptor 1 (NMDAR 1) and neuronal constitutive nitric oxide synthase (ncNOS) mRNA in rat spinal cord was detected by in situ hybridization. Results: Abnormal expression of NMDAR 1 and ncNOS mRNA appeared in spinal ventral horn motorneuron in injured rats, as compared with that in control group. The expression of NMDAR 1 and ncNOS mRNA in NGF group was significantly lower than that in saline group (P<0.01). Conclusion: NGF can protect spinal cord against injury in vivo. One of the mechanisms is that NGF can prohibit NMDAR 1 and nitric oxide (NO) production after spinal cord injury.
文摘AIM: To develop a PCR assay using mutant-specific primers to detect mutation of tyrosine-methionine-aspartate-aspartate (YMDD) motif of HBV to tyrosine-valine-aspartate-aspartate (YVDD) or tyrosine-isoleucine-aspartate-aspartate (YIDD).METHODS: Cloned wild-type and mutant HBV sequences were used as templates to test the sensitivity and specificity of the assay. A variety of primer construction, primer concentration, dNTP concentration, and annealing temperature of primers were systematically examined. Pair primers specifi c to rtL180M and rtM204V were selected for YVDD detection. Primer specif ic to rtM204I with an additional 3’-penultimate base mismatched to both the mutant and wild-type sequence was selected for YIDD detection. We applied this assay to study YMDD mutants in 28 chronic hepatitis B patients before and after lamivudine treatment.RESULTS: We could detect as little as 0.001%-0.00001% of mutant viruses coexisting in 108-109 copies of wild-type HBV using this assay. YMDD mutants were detected in 8 of 12 HBeAg-positive patients and 8 of 16 HBeAg-negative patients before lamivudine treatment. After treatment, two more patients in HBeAg-positive patients and seven more patients in HBeAg-negative patients developed YMDD mutations. CONCLUSION: We developed a highly sensitive and specifi c assay for detecting YMDD mutants. This assay can be applied to monitor chronic hepatitis B patients before and during lamivudine treatment.
