BACKGROUND: Cirrhosis can cause severe effect on spinal cord or other tissue and organ sometimes.OBJECTIVE: To establish cirrhosis model with rat liver injured by tetrachloride so as to investigate the distribution of nitric oxide synthase (NOS)in spinal cord of rats with cirrhosis.DESIGN: Completely randomized controlled study.SETTING: Anatomy Department of Capital University of Medical Sciences.MATERIALS: The experiment was completed at the Anatomy Department of Capital University of Medical Sciences from March 2002 to December 2003. Totally 20 male Wistar rats were divided randomly into cirrhosis group and normal group with 10 in each group.METHODS: Cirrhosis model in cirrhosis group was established with rat liver injured by tetrachloride, but rats in normal group were not treated with any method. After 3 months, total rats in the two groups were perfused and fixed; meanwhile, tissue of spinal cord was taken out for section.Quantity and gray degree of NOS positive cell in spinal cord of rats with cirrhosis were measured with nicotinamide adenine dinucleotide hydrogen phosphate-diaphorase (NADHP-d) histochemical method and Leica Q500IW image analysis system.MAIN OUTCOME MEASURES: [1] Gray degree of NOS positive neurons of rats in the two groups; [2] Distribution of NOS positive cell of rats in the two groups.RESULTS: Twenty rats all entered the final analysis. [1] Gray degree of NOS positive neurons of rats in the two groups was 60 (P ＞ 0.05). [2] In the area of gray matter of spinal cord, NOS positive cells were mainly distributed over the circumference of central canal, i.e. the Ⅹ layer of spinal cord and intermediolateral nucleus. Color of NADHP-d was positive, and the cellular form was shaped in triangle and fusiform. Cellular nucleus was not colored but color of cytoplasm was deep. The size of cells was moderate mainly of 25 μm. NOS positive cells were generally distributed averagely over intermediate zone of gray matter in cervical, thoracic and lumbar spinal cord and had no specific changes.CONCLUSION: Expression of NOS in spinal cord of rats in the cirrhosis group and the normal group is probably identical. Distributive characteristics of nitrogen monoxide (NO) in spinal cord suggest that adjustment on low sympathetic nerve of rats with cirrhosis is not different from that of the normal.

Objective Tanycytes(TAs) is a specialized eppendymal glia that locates mostly in the ventral lateral wall of the ventricle III and median eminence(ME).Due to its peculiar location and directly exposure to the cerebrospinal fluid,blood,neuroendocrine hormones and neurons,tanycytes play an important role in the brain barrier system,brain-CSF neurohumoral circuit and immune-neuroendocrine network.They maintain immature characters during the adulthood and have naturally conducted the neuroregeneration process in the adult hypothalamus of mammal animals.This research was designed to identify tanycytes(TAs) in postnatal 7 days of Wistar rats and then establish the cell model of TAs for further study.Methods Tanycytes of postnatal 7 days of Wistar rats were identified by the immunohistochemical technology using glial fibrillary acidic protein(GFAP) and vimentin(VIM),which are the intermediate filament markers of glia cells.The qualitative analysis was performed by the NADPH-d stain of nitric oxide sythenase(NOS).Primary TAs model was established by the cell culture technique and identified by the same methods as in vivo.Results Primary cultured TAs expressed VIM,GFAP and NOS which was identical with those in vivo.Conclusion Cell model of TAs from postnatal 7days of Wistar rats in vitro has been established and TAs could be used as a proper substrate for transplanting.

ObjectiveTo explore the projections of the long descending propriospinal tracts to lumbar enlargement. Method　Anterograde tracing with cupric-silver staining. 10 animals were injected b biotinylated dextran in the upper cervical cord. Following survival times of 14 days, projections of the long descending propriospinal tracts were immunohistochemically demonstrated in the lumbar enlargement.Results　The degenerated terminals and labeled terminals were found in the bilateral gray matter of the lumbar enlargement, but predominantly ipsilaterally. The terminals were widely distributed in laminal Ⅴ-Ⅸ, heavily Ⅶ and Ⅷ. Conclusion　The long descending propriospinal tract from the upper cervical cord projects to the lumbar enlargement.

The direct spinal projections from the cerebellar nuclei in the rabbit were retro gradely traced by unilateral injection of WGA-HRP into different levels of the spinal cord, including the cervical, thoracic and lumbar segments. The labeled neurons in the cerebellar nuclei were constantly seen in those animals, in which the upper cervical segments (C_(2-4)) were injected. No labeled neurons could be found in the cerebellar nuclei following injection into the lower cervical cord (C_(6-8)) or more caudal segments. All labeled neurons were located in the caudal parts of the fastigial and the interposed nuclei on the side contralateral to the injection. The results show that there are crossed projections from the cerebellar nuclei directly to the upper cervical cord. This study provide certain morphological evidences for further investigation of some aspects of cerebellar functions on motor coordination.

Objective To study the changes of NOS positive neurons in cortex motor area and spinal cord in rats of cirrhosis with portacaval shunts. Methods NADPH-diaphorase, fluorescence immunohistochemistry with confocal laser scanning microscope (CLSM) were used. Results The number of NOS and nNOS positive neurons in cirrhosis rats with portacaval shunts decreased obviously.Conclusion Cirrhosis with portacaval shunts can influence motor neurons of cortex; NO may participate in the central nervous system changes of cirrhosis rats with portacaval shunts.;

Objective To approach the neurobiochemical mechanism of chronic central pain (CCP) after spinal cord injury (SCI). Methods 28 SD rats were divided into four groups, the normal group (group A), the pseudosurgery group (group B), and groups with CCP (group C) and without CCP (group D) after L1 spinal cord section injured with WADE method. T13 and L2 segments of rats' spinal cord were took and concentration changes of substance P (SP) in the spinal dorsal horn between two sections were examined by immunofluorescence histochemistry staining combined with confocal laser scanning microscope. Results Concentration of SP in the group D was decreased significantly compared with groups C,A and B (P<0.05-0.01), that of the group C was less than that of group A and B (P<0.05). Conclusion The rat model established by WADE method is proper to study CCP after SCI. SP in dorsal horn of spinal cord may inhibit the CCP after SCI in some degrees.

Objective To investigate the mechanism of the soluble A? oligomers-induced alteration of synaptic proteins. Methods This study applied immunocytochemistry technique to investigate the changes of the expression of postsynaptic density-95(PSD-95) in primary hippocampal neurons, which was exposed to A?_ 25-35 after NMDAR antagonist or agonist treatment. Results The results showed that A?_ 25-35 downregulated PSD-95 protein in a dose- and time-dependent manner. Treatment of cells with MK801 (a general NMDA receptor antagonist) prevented A?-induced PSD-95 degradation. Moreover, when extrasynaptic NMDA receptors were blocked by ifenprodil (a NR2B subunit specific antagonist), the A?-induced downregulation of PSD-95 was significantly attenuated. Whereas, when synaptic NMDA receptors were blocked by bicuculline (a GABA receptor antagonist) in combination with MK801, the PSD-95 degradation did not change significantly.Conclusion The results suggest that A?-induced downregulation of PSD-95 depends on NMDAR activity, and extrasynaptic NMDA receptors may be involved in A?-induced synaptic protein degradation.

Shikimic acid is an intermediate metabolite in the synthesis of aromatic amino acids in Escherichia coli and a synthetic precursor of Tamiflu. The biosynthesis of shikimic acid requires blocking the downstream shikimic acid consuming pathway that leads to inefficient production and cell growth inhibition. In this study, a dynamic molecular switch was constructed by using growth phase-dependent promoters and degrons. This dynamic molecular switch was used to uncouple cell growth from shikimic acid synthesis, resulting in the production of 14.33 g/L shikimic acid after 72 h fermentation. These results show that the dynamic molecular switch could redirect the carbon flux by regulating the abundance of target enzymes, for better production.
Escherichia coli/genetics* ; Escherichia coli Proteins/genetics* ; Industrial Microbiology/methods* ; Metabolic Engineering ; Shikimic Acid/metabolism*

Human activities increase the concentration of atmospheric carbon dioxide (CO₂), which leads to global climate warming. Microbial CO₂ fixation is a promising green approach for carbon neutral. In contrast to autotrophic microorganisms, heterotrophic microorganisms are characterized by fast growth and ease of genetic modification, but the efficiency of CO₂ fixation is still limited. In the past decade, synthetic biology-based enhancement of heterotrophic CO₂ fixation has drawn wide attention, including the optimization of energy supply, modification of carboxylation pathway, and heterotrophic microorganisms-based indirect CO₂ fixation. This review focuses on the research progress in CO₂ fixation by heterotrophic microorganisms, which is expected to serve as a reference for peaking CO₂ emission and achieving carbon neutral by microbial CO₂ fixation.
Carbon Cycle ; Carbon Dioxide/metabolism* ; Heterotrophic Processes ; Humans ; Synthetic Biology

Microbial cell factories capable of producing valuable chemicals from renewable feedstocks provide a promising alternative towards sustainability. However, environmental stress remarkably affects the performance of microbial cell factories. By extending the chronological lifespan of microbial cells, the performance of microbial cell factories can be greatly improved. Firstly, an evaluation system for chronological lifespan and semi-chronological lifespan was established based on the changes in survival rates. Secondly, the addition of anti-aging drugs such as cysteine, carnosine, aminoguanidine and glucosamine increased the chronological lifespan of E. coli by 80%, 80%, 50% and 120%, respectively. Finally, we demonstrated that extending the chronological lifespan of E. coli increased the yield of metabolites produced by E. coli cell factories with endogenous (lactic acid and pyruvic acid) or exogenous (malic acid) metabolic pathway by 30.0%, 25.0%, and 27.0%, respectively. The strategy of extending chronological lifespan of E. coli provides a potential approach for enhancing the performance of microbial cell factories.
Escherichia coli/genetics* ; Lactic Acid ; Longevity ; Metabolic Engineering ; Metabolic Networks and Pathways