Obgective To observe the effect of hydrogen sulfide (H2S) on vasorelaxation and expression of guanosine 3',5'-cyclic phosphate (cGMP) and activity of cyclic nucleotide phosphodiesterase (PDE) in vascular tissue.Methods H2S donor was provided by sodium bisulfide sodium hydrosulfide.The isolated perfused rat thoracic aorta rings were used to test the relaxation responses to H2S,which recorded by Power Lab system,and the enzyme linked immuno assay was used to detect intracellular cGMP.The activity of PDE was evaluated by using cyclic nucleotide PDE assay kit.Results (1) H2S relaxed the thoracic aorta rings,and the half maximal effective concentration (EC50) for the H2 S relaxation curve,represented by the corresponding concentration of H2 S that achieved 50％ of the maximum relaxation effect,was (1.79 ± 0.31) × 10-5 mol/L.(2)The cGMP content in vascular tissue increased from (22.29 ± 1.59) pmol/L to(41.45 ± 7.49) pmol/L and (31.35 ± 2.56) pmol/L after incubation with 50 μmol/L and 300 μmol/L H2 S,respectively (t =-3.09,t =-2.88;all P ＜ 0.05,n =7-8).(3) cGMP could be lysed into 5'-guanylicacid(5'-GMP) by PDE,which was an important pathway for cGMP degradation.This study showed that PDE activity was decreased in vascular tissue,the 5'-GMP decreased from (0.52 ±0.06) mol/L to (0.25 ±0.06) mol/Land (0.27 ±0.07) mol/L after incubation with 50 μmol/L and 300 μ mol/L H2S,respectively (t =3.21,t =2.58;all P ＜ 0.05,n =7-8).Conclusion The vasorelaxant effects of H2 S might be related to the inhibited activity of PDE and elevated content of cGMP.

Objective To investigate MRI characteristics of subacute combined degeneration(SCD)with secondary spinal canal stenosis.Methods The clinical and MRI imaging data of 56 patients with SCD were collected to analyze the performance characteristics between spinal cord lesions and spinal canal stenosis,which depended on the synergism of lumbar disc bluge or herniation,degenerative thickening of the ligament flavum and posterior longitudinal ligament.Results Among 56 SCD cases underwent MRI scan,45 cases were combined with spinal cord lesions which showed typical signs of SCD.37 patients were secondary spinal canal stenosis with typical signs,but 2 showed no typical signs.8 patients were no secondary spinal canal stenosis and showed typical.9 cases showed neither spinal cord lesions nor secondary spinal canal stenosis.There was significant difference (P <0.05)between relative secondary spinal canal stenosis and spinal anomaly signal.The course of 1 5 cases were shortened after treated by physical in 37 cases of SCD with secondary spinal canal. Conclusion The secondary spinal canal stenosis can cause microcirculation dysfunction of the spinal cord,which is a key factor contributing to the imaging manifestation.

Objective:To observe the effect of noninvasive positive pressure ventilation (NIPPV) and high-flow nasal cannula oxygen therapy (HFNC) on the prognosis of patients with coronavirus disease 2019 (COVID-19) accompanied with acute respiratory distress syndrome (ARDS).Methods:A retrospective study was conducted in Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology when authors worked as medical team members for treating COVID-19. COVID-19 patients with pulse oxygen saturation/fraction of inspiration oxygen (SpO 2/FiO 2, S/F) ratio < 235, managed by medical teams [using S/F ratio instead of oxygenation index (PaO 2/FiO 2) to diagnose ARDS] from February to April 2020 were included. The patients were divided into NIPPV group and HFNC group according to their oxygen therapy modes. Clinical data of patients were collected, including general characteristics, respiratory rate (RR), fraction of FiO 2, SpO 2, heart rate (HR), mean arterial pressure (MAP), S/F ratio in the first 72 hours, lymphocyte count (LYM), percentage of lymphocyte (LYM%) and white blood cell count (WBC) at admission and discharge or death, the duration of dyspnea before NIPPV and HFNC, and the length from onset to admission. The differences of intubation rate, all-cause mortality, S/F ratio and RR were analyzed, and single factor analysis and generalized estimation equation (GEE) were used to analyze the risk factors affecting S/F ratio. Results:Among the 41 patients, the proportion of males was high (68.3%, 28 cases), the median age was 68 (58-74) years old, 28 cases had complications (68.3%), and 34 cases had multiple organ dysfunction syndrome (MODS, 82.9%). Compared with HFNC group, the proportion of complications in NIPPV group was higher [87.5% (21/24) vs. 41.2% (7/17), P < 0.05], and the value of LYM% was lower [5.3% (3.4%-7.8%) vs. 10.0% (3.9%-19.7%), P < 0.05], the need of blood purification was also significantly lower [0% (0/24) vs. 29.4% (5/17), P < 0.05]. The S/F ratio of NIPPV group gradually increased after 2 hours treatment and RR gradually decreased with over time, S/F ratio decreased and RR increased in HFNC group compared with baseline, but there was no significant difference in S/F ratio between the two groups at each time point. RR in NIPPV group was significantly higher than that in HFNC group after 2 hours treatment [time/min: 30 (27-33) vs. 24 (21-27), P < 0.05]. There was no significant difference in rate need intubation and hospital mortality between NIPPV group and HFNC group [66.7% (16/24) vs. 70.6% (12/17), 58.3% (14/24) vs. 52.9% (9/17), both P > 0.05]. Analysis of the factors affecting the S/Fratio in the course of oxygen therapy showed that the oxygen therapy mode and the course of illness at admission were the factors affecting the S/F ratio of patients [ β values were -15.827, 1.202, 95% confidence interval (95% CI) were -29.102 to -2.552 and 0.247-2.156, P values were 0.019 and 0.014, respectively]. Conclusion:Compared with HFNC, NIPPV doesn't significantly reduce the intubation rate and mortality of patients with COVID-19 accompanied with ARDS, but it significantly increases the S/F ratio of those patients.

OBJECTIVE：To study the protective effect of tadehaginoside（TA）on liver fibrosis model mice induced by carbon tetrachloride（CCl4），and to investigate its mechanism. METHODS ：Kunming mice were randomly divided into normal group ， model group ，colchicines group （positive control ，0.2 mg/kg），TA low-dose ，medium-dose and high-dose groups （3，6，12 mg/kg），with 10 mice in each group. Those groups were intraperitoneally injected with 10％ CCl4-olive oil solution （5 mL/kg）to induce liver fibrosis model twice a week ，for consecutive 8 weeks；except that ，the normal group was intraperitoneally injected with olive oil. From 3rd week ，the mice in each administration groups were given relevant medicine intragastrically ，normal group and model group were given constant volume 2％ sodium carboxymethylcellulose solution intragastrically ，once a day ，for consecutive 6 weeks. The contents of ALT ，AST，HA and IL- 6 in serum of mice were test ed by ELISA. The contents of Hyp ， SOD，MDA and GSH-Px in liver tissues were detected by spectrophotometry. mRNA expression of Col- Ⅰ，TIMP-1 and TIMP-2 in liver tissue was detected by RT-PCR. The protein expression of MMP- 2 and TGF-β1 in liver tissue was detected by Western blotting. RESULTS ： Compared with normal group，the contents of ALT，AST，HA，IL-6，MDA and Hyp，the mRNA expression of Col- Ⅰ，TIMP-1 and TIMP- 2，as well as the protein exp ression of MMP- 2 and TGF-β1 were increased significantly ，while the contents of SOD and GSH-Px were decreased significantly （P＜0.01）. Compared with model group，the contents of ALT ，AST，HA，IL-6，MDA and Hyp ，the mRNA expression of Col- Ⅰ，TIMP-1 and TIMP- 2，as well as the protein expression of MMP- 2 and TGF-β1were decreased significantly ，while the contents of SOD and GSH-Px were increased significantly（P＜0.05 or P＜0.01）. CONCLUSIONS ：TA has a significant protective effect on liver tissue and anti-fibrosis effects in liver fibrosis model mice ，the mechanism of which may be associated with inhibiting lipid peroxidation and collagen synthesis ， down-regulating the mRNA expression of Col- Ⅰ，TIMP-1 and TIMP- 2 as well as the protein expression of MMP- 2 and TGF-β1.

Sucrose is a natural product occurs widely in nature. In living organisms such as plants, sucrose phosphate synthase (SPS) is the key rate-limiting enzyme for sucrose synthesis. SPS catalyzes the synthesis of sucrose-6-phosphate, which is further hydrolyzed by sucrose phosphatase to form sucrose. Researches on SPS in recent decades have been focused on the determination of enzymatic activity of SPS, the identification of the inhibitors and activators of SPS, the covalent modification of SPS, the carbohydrate distribution in plants regulated by SPS, the mechanism for promoting plant growth by SPS, the sweetness of fruit controlled by SPS, and many others. A systematic review of these aspects as well as the crystal structure and catalytic mechanism of SPS are presented.
Carbohydrate Metabolism ; Glucosyltransferases/metabolism* ; Plants/metabolism* ; Sucrose