试论突发公共卫生事件应急机制的建立

非典型肺炎疫情的发生 ,对我国现有的公共卫生机制敲响了警钟。该文借鉴国外处理类似事件的成功经验 ,结合中国实际情况 ,认为应该通过建立突发事件的预警机制和专门领导机构 ,健全信息披露机制 ,强化干部问责与纠错机制 ,建立财政资源和社会力量的动员与参与机制 ,运用法律强制机制 。

Initial Study on Immune Escape Mechanism of Mouse Acute Myelomonocytic Leukemic Cell Line WEHI-3

Objective： To investigate the expression of Fas, Fas ligand （FasL） and CD80 on the cell surface of mouse acute myelomonocytic leukemia cell line WEHI-3 and the function of FasL. Methods： The expression of Fas, FasL and CD80 was detected on WEHI-3 cell surface by flow cytometry. Simultaneously the function of FasL was determined by Thymidine （^3H-TdR） Incorporation. Results： The expression of CD80 and Fas on WEHI-3 cell surface was 5.06%±0.41% and 6.75%±2.31% （n=5） respectively, and the expression of FasL was up to 63.73%±5.23% （n=5）. The apoptotic rate of YAC-1 cells was 26%±4.5%, 35%±3.2% and 43%±2.7% （n=5） respectively when WEHI-3 （effector cell, E） and Fas^＋ YAC-1 cells （target cell, T） were cultured in the ratio of 3：1, 10：1 and 30：1. Conclusion： WEHI-3 cells express high FasL, low Fas and CD80, and can induce apoptosis of Fas^＋ YAC-1 cells.

Supply chain coordination mechanisms under asymmetric information with retailer cost disruptions

A two-level supply chain model involving one supplier and one retailer with linear demand is developed, and supply chain coordination mechanisms under asymmetric information （the retailer＇ s cost structure is asymmetric information） are proposed by employing game theory in two scenarios： coordination mechanisms under asymmetric information in a regular scenario （without disruption）; and coordination mechanisms under asymmetric information in an irregular scenario （ with retailer cost disruptions）. It is optimal for the supply chain to maintain the original production plan and to guarantee a steadily running system if variations of retailer costs are sufficiently low and do not exceed an upper bound. This shows that the original production plan has certain robustness under disruptions. Decisions must be re-made if a retailer＇ s cost change is greater and exceeds an upper bound. Impacts of retailer cost disruptions on the order quantity, the retail price, the wholesale price and each party＇ s as well as the system＇ s expected profits are investigated through numerical analyses.

入世与我国经济安全问题的思考

入世的重要意义在于加速了中国融入世界经济全球化体系的进程,但鉴于发达国家和发展中国家各自在经济全球化体系中所扮演的不同角色和所起到的不同作用,入世后在获取贸易投资自由化好处的同时,防范经济全球化的风险以维护我国经济安全显得尤为重要。但对此我们也不能太悲观,要正确认识入世给我国带来的安全和不安全因素,并学会借助WTO保障机制维护我国经济安全。

一种快速冷却超高温流体方法的数值模拟

在许多强吸热化学反应的化工过程中,常常需要对反应流体流出反应器时进行快速急冷来避免副反应或逆反应发生,以期最终获得可观的目标产物。在本实验室前期开展的热等离子体裂解二氧化碳实验研究中,采取在高温反应器出口加装收缩喷管将裂解气高速导入夹套水冷管的方法,实现了对高温裂解气的快速急冷,显著地避免了裂解气中CO与O的逆反应,获得了意想不到的CO_2高转化率。本文利用计算流体力学软件模拟这一过程,以期揭示这种新的冷却方法导致极快速冷却的机制。模拟结果表明,加装收缩喷嘴确实可以期待对高温射流产生10~7 K·s^(-1)量级的温降速率。深入分析表明,仅仅靠气体动力学效应不能完全解释如此快速的冷却速率。从喷管高速喷出的黏性流体在夹套水冷管内形成高速涡流,这种涡流一方面增强了主流体对周围气体的卷吸,另一方面加强了被卷吸流体在被卷入之前与夹套水冷管壁面的强制换热过程,是导致快速急冷的主要机制。

Transboundary water vulnerability and its drivers in China

Competitive use of transboundary freshwater resources is becoming one of the key factors influencing regional peace and political relationship among states.In China, 18 major international river basins are concentrated in three regions, of which the total annual outflow at the border is 7320×108 m3, occupying 26.8% of the total annual runoff of China, and the inflow at the border is only 172×108 m3.In this paper, we analyzed the major drivers affecting shared water vulnerability in China, namely:(1) changes in physical conditions affecting the availability of water;(2) competing objectives between economic development and ecological conservation;(3) lack of emergency response mechanisms;(4) unsound administrative institutions;and(5) shortcomings in the development of regional cooperation based on transboundary waters.We concluded by identifying four pathways for reducing vulnerability:(1) encouraging scientific research cooperation;(2) constructing information-sharing channels;(3) establishing early-warning mechanisms;and(4) promoting further coordination and negotia-tion.

Acute pancreatitis:Etiology and common pathogenesis

Acute pancreatitis is an inflammatory disease of the pancreas.The etiology and pathogenesis of acute pancreatitis have been intensively investigated for centuries worldwide.Many causes of acute pancreatitis have been discovered,but the pathogenetic theories are controversial.The most common cause of acute pancreatitis is gallstone impacting the distal common bile-pancreatic duct.The majority ofinvestigators accept that the main factors for acute billiary pancreatitis are pancreatic hyperstimulation and bile-pancreatic duct obstruction which increase pancreatic duct pressure and active trypsin reflux.Acute pancreatitis occurs when intracellular protective mechanisms to prevent trypsinogen activation or reduce trypsin activity are overwhelmed.However,little is known about the other acute pancreatitis.We hypothesize that acute biliary pancreatitis and other causes of acute pancreatitis possess a common pathogenesis.Pancreatic hyperstimulation and pancreatic duct obstruction increase pancreatic duct pressure,active trypsin reflux,and subsequent unregulated activation of trypsin within pancreatic acinar cells.Enzyme activation within the pancreas leads to auto-digestion of the gland and local inflammation.Once the hypothesis is confirmed,traditional therapeutic strategies against acute pancreatitis may be improved.Decompression of pancreatic duct pressure should be advocated in the treatment of acute pancreatitits which may greatly improve its outcome.

Severe acute pancreatitis: Pathogenetic aspects and prognostic factors

Approximately 20% of patients with acute pancreatitis develop a severe disease associated with complications and high risk of mortality. The purpose of this study is to review pathogenesis and prognostic factors of severe acute pancreatitis （SAP）. An extensive medline search was undertaken with focusing on pathogenesis, complications and prognostic evaluation of SAP. Cytokines and other inflammatory markers play a major role in the pathogenesis and course of SAP and can be used as prognostic markers in its early phase. Other markers such as simple prognostic scores have been found to be as e^ective as multifactorial scoring systems （MFSS） at 48 h with the advantage of simplicity, efficacy, low cost, accuracy and early prediction of SAP. Recently, several laboratory markers including hematocrit, blood urea nitrogen （BUN）, creatinine, matrix metalloproteinase-9 （MMP-9） and serum amyloid A （SAA） have been used as early predictors of severity within the first 24 h. The last few years have witnessed a tremendous progress in understanding the pathogenesis and predicting the outcome of SAP. In this review we classified the prognostic markers into predictors of severity, pancreatic necrosis （PN）, infected PN （IPN） and mortality.

Pancreatic regenerating protein (regⅠ) and regⅠreceptor mRNA are upregulated in rat pancreas after induction of acute pancreatitis

AIM： Pancreatic regenerating protein （reg Ⅰ ） stimulates pancreatic regeneration after pancreatectomy and is mitogenic to ductal and 13-cells. This suggests that reg Ⅰand its receptor may play a role in recovery after pancreatic injury. We hypothesized that reg Ⅰ and its receptor are induced in acute pancreatitis. METHODS： Acute pancreatitis was induced in male Wistar rats by retrograde injection of 3% sodium taurocholate into the pancreatic duct. Pancreata and serum were collected 12, 24, and 36 hours after injection and from normal controls （4 rats/group）. Reg Ⅰ receptor mRNA, serum reg Ⅰ protein, and tissue reg Ⅰ protein levels were determined by Northern analysis, enzymelinked immunosorbent assay （ELISA）, and Western analysis, respectively. Immunohistochemistry was used to localize changes in reg Ⅰ and its receptor. RESULTS： Serum amylase levels and histology confirmed necrotizing pancreatitis in taurocholate treated rats. There was no statistically significant change in serum reg Ⅰ concentrations from controls. However, Western blot demonstrated increased tissue levels of reg Ⅰ at 24 and 36 h. This increase was localized primarily to the acinar cells and the ductal cells by immunohistochemistry. Northern blot demonstrated a significant increase in reg Ⅰ receptor mRNA expression with pancreatitis. Immunohistochemistry localized this increase to the ductal cells, islets, and acinar cells. CONCLUSION： Acute pancreatitis results in increased tissue reg Ⅰ protein levels localized to the acinar and ductal cells, and a parallel threefold induction of reg Ⅰ receptor in the ductal cells, islets, and acinar cells. These changes suggest that induction of reg Ⅰand its receptor may be important for recovery from acute pancreatitis.

Effect of admission hypertriglyceridemia on the episodes of severe acute pancreatitis

AIM： To investigate the effect of admission hypertriglyceridemia （HTG） on the episodes of severe acute pancreatitis （SAP）. METHODS： One hundred and seventy-six patients with SAP were divided into HTG group （n = 45） and control group （n = 131） according to admission triglyceride （TG） ≥ 5.65 mmol/L and 〈 5.65 retool/L, respectively. Demographics, etiology, underlying diseases, biochemical parameters, Ranson＇ s score, acute physiology and chronic heath evaluation Ⅱ （APACHE Ⅱ） score, Balthazar＇s computed tomography （CT） score, complications and mortality were compared. Correlation between admission TG and 24-h APACHE Ⅱ score was analyzed. RESULTS： SAP patients with HTG were younger （40.8 ± 9.3 years vs 52.6 ± 13.4 years, P 〈 0.05） with higher etiology rate of overeating, high-fat diet （40.0% vs 14.5%, P 〈 0.05） and alcohol abuse （46.7% vs 23.7%, P 〈 0.01）, incidence rate of hypocalcemia （86.7% vs 63.4%, P 〈 0.01） and hypoalbuminemia （84.4% vs 60.3%, P 〈 0.01）, 24-h APACHE Ⅱ score （13.6 ± 5.7 vs 10.7 ± 4.6, P 〈 0.01） and admission serum glucose （17.7 ± 7.7 vs 13.4 ± 6.1, P 〈 0.01）, complication rate of renal failure （51.1% vs 16.8%, P 〈 0.01）, shock （37.9% vs 14.5%, P 〈 0.01） and infection （37.4% vs 18.3%, P 〈 0.01） and mortality （13.1% vs 9.1%, P 〈 0.01）. Logistic regression analysis showed a positive correlation between admission TG and 24-h APACHE Ⅱ score （r = 0.509, P = 0.004）.CONCLUSION： The clinical features of SAP patients with HTG are largely consistent with previous studies, HTG aggravates the episodes of SAP.

Timing of laparoscopic cholecystectomy for acute cholecystitis: A prospective non randomized study

AIM： To study the timing of laparoscopic cholecystectomy for patients with acute cholecystitis. METHODS： Between January 2002 and December 2005, all American Society of Anesthesiologists classification （ASA） Ⅰ ,Ⅱ and Ⅲ patients with acute cholecystitis were treated laparoscopically during the urgent （index） admission. The patients were divided into three groups according to the timing of surgery： （1） within the first 3 d, （2） between 4 and 7 d and （3） beyond 7 d from the onset of symptoms. The impact of timing on the conversion rate, morbidity and postoperative hospital stay was studied. RESULTS： One hundred and twenty-nine patients underwent laparoscopic cholecystectomy for acute cholecystitis during the index admission. Thirty six were assigned to group 1, 58 to group 2, and 35 to group 3. The conversion rate and morbidity for the whole cohort of patients were 4.6% and 10.8%, respectively. There was no significant difference in the conversion rate, morbidity and postoperative hospital stay between the three groups.CONCLUSION： Laparoscopic cholecystectomy for acute cholecystitis during the index admission is safe, regardless of the time elapsed from the onset of symptoms. This policy can result in an overall shorter hospitalization.

Spontaneous chylous peritonitis mimicking acute appendicitis:A case report and review of literature

Acute abdominal pain with signs and symptoms of peritonitis due to sudden extravasation of chyle into the peritoneal cavity is a rare condition that is often mistaken for other disease processes. The diagnosis is rarely suspected preoperatively. We report a case of spontaneous chylous peritonitis that presented with typical symptoms of acute appendicitis such as intermittent fever and epigastric pain radiating to the lower right abdominal quadrant before admission.

Pravastatin:A potential cause for acute pancreatitis

Acute pancreatitis （AP） secondary to drugs is uncommon, with an incidence ranging from 0.3% to 2.0% of AP cases. Drug-induced AP due to statins is rare, and only 12 cases have thus far been reported. In this case report, we report a case of a 50-year-old female on pravastatin therapy for 3 d prior to developing symptoms of AP. The common etiological factors for AP were all excluded. The patient was admitted to the intensive care unit secondary to respiratory distress, though she subsequently improved and was discharged 14 d after admission. Although the incidence of drug-induced AP is low, clinicians should have a high index of suspicion for it in patients with AP due to an unknown etiology. Clinicians should be aware of the association of statins with AR If a patient taking a statin develops abdominal pain, clinicians should consider the diagnosis of AP and conduct the appropriate laboratory and diagnostic evaluation if indicated.

Numerical Simulation of the Heavy Rainfall in the Yangtze-Huai River Basin during Summer 2003 Using the WRF Model

In this study, a 47-day regional climate simulation of the heavy rainfall in the Yangtze-Huai River Basin during the summer of 2003 was conducted using the Weather Research and Forecast （WRY） model. The simulation reproduces reasonably well the evolution of the rainfall during the study period＇s three successive rainy phases, especially the frequent heavy rainfall events occurring in the Huai River Basin. The model captures the major rainfall peak observed by the monitoring stations in the morning. Another peak appears later than that shown by the observations. In addition, the simulation realistically captures not only the evolution of the low-level winds but also the characteristics of their diurnal variation. The strong southwesterly （low-level jet, LLJ） wind speed increases beginning in the early evening and reaches a peak in the morning; it then gradually decreases until the afternoon. The intense LLJ forms a strong convergent circulation pattern in the early morning along the Yangtze-Huai River Basin. This pattern partly explains the rainfall peak observed at this time. This study furnishes a basis for the further analysis of the mechanisms of evolution of the LLJ and for the further study of the interactions between the LLJ and rainfall.

Preventive effect of tetramethylpyrazine on intestinal mucosal injury in rats with acute necrotizing pancreatitis

AIM： To evaluate the role of microcirculatory disorder （MCD） and the therapeutic effectiveness ;of tetramethylpyrazine （TMP） on intestinal mucosa injury in rats with acute necrotizing pancreatitis （ANP）.METHODS： A total of 192 Sprague-Dawley rats were randomly divided into three groups： normal control group （C group）, ANP group not treated with TMP （P group）, ANP group treated with TMP （T group）. An ANP model was induced by injection of 50 g/L sodium taurocholate under the pancreatic membrane （4 mL/kg）. C group received isovolumetric injection of 9 g/L physiological saline solution using the same method. T group received injection of TMP （10 mL/kg） via portal vein. Radioactive biomicrosphere technique was used to measure the blood flow at 0.5, 2, 6 and 12 h after the induction of ANP. Samples of pancreas, distal ileum were collected to observe pathological changes using a validated histology score. Intestinal tissues were also used for examination of myeloperoxidase （MPO） expressed intraceUularly in azurophilic granules of neutrophils.RESULTS： The blood flow was significantly lower in P group than in C group （P 〈 0.01）. The pathological changes were aggravated significantly in P group. The longer the time, the severer the pathological changes. The intestinal MPO activities were significantly higher in P group than in C group （P 〈 0.01）. The blood flow of intestine was significantly higher in T group than in P group after 2 h （P 〈 0.01）. The pathological changes were alleviated significantly in T group. MPO activities were significantly lower in T group than in P group （P 〈 0.01 or P 〈 0.05）. There was a negative correlation between intestinal blood flow and MPO activity （r = -0.981, P 〈 0.01） as well as between intestinal blood flow and pathologic scores （r = -0.922, P 〈 0.05）.CONCLUSION： MCD is an important factor for intestinal injury in ANP. TMP can ameliorate the condition of MCD and the damage to pancreas and intestine.

Is leptin related to systemic inflammatory response in acute pancreatitis?

AIM： To evaluate the relationship between leptin and systemic inflammation in acute pancreatitis. METHODS： Consecutive patients with acute pancreatitis were included. Body mass index and serum samples were obtained at admission. Leptin, TNF-α, IL-6, -8 and -10 levels were determined by ELISA. Severity was defined according to Atlanta criteria. RESULTS： Fifty-two （29 females） patients were studied. Overall body mass index was similar between mild and severe cases, although women with severe pancreatitis had lower body mass index （P = 0.04） and men showed higher body mass index （P = 0.05）. No difference was found in leptin levels regarding the severity of pancreatitis, but higher levels tended to appear in male patients with increased body mass index and severe pancreatitis （P = 0.1）. A multivariate analysis showed no association between leptin levels and severity. The strongest cytokine associated with severity was IL-6. Correlations of leptin with another cytokines only showed a trend for IL-8 （P = 0.058）. CONCLUSION： High body mass index was associated with severity only in males, which may be related to android fat distribution. Serum leptin seems not to play a role on the systemic inflammatory response in acute pancreatitis and its association with severe outcome in males might represent a marker of increased adiposity.

Nuclear factor-kappaB activation on the reactive oxygen species in acute necrotizing pancreatitic rats

AIM： To investigate the potential role of nuclear factor kappa-B （NF-κB） activation on the reactive oxygen species in rat acute necrotizing pancreatitis （ANP） and to assess the effect of pyrrolidine dithiocarbamate （PDTC, an inhibitor of NF-κB）.METHODS： Rat ANP model was established by retrograde injection of 5% sodium taurocholate into biliopancreatic duct. Rats were randomly assigned to three groups （10 rats each）： Control group, ANP group and PDTC group. At the 6^th of the model, the changes of the serum amylase,nitric oxide （NO）, malondialdehyde （MDA）, superoxide dismutase （SOD） and pancreatic morphological damage were observed. The expressions of inducible nitric oxide （iNOS） were observed by SP immunohistochemistry. And bhe expressions of NF-κB p65 subunit mRNA were observed by hybridization in situ.RESULTS： Serum amylase and NO level decreased significantly in ANP group as compared with PDTC administrated group [（7 170.40＋1 308.63） U/L vs（4 074.10＋1 719.78） U/L,P〈0.05], [（76.95±9.04） μmol/L vs （65.18±9.02） μmol/L,P〈0.05] respectively. MDA in both ANP and PDTC group rose significantly over that in control group [（9.88＋1.52）nmol/L, （8.60±1.41） nmol/L, vs （6.04：hl.78） nmol/L,P〈0.05], while there was no significant difference between them. SOD levels in both ANP and PDTC group underwent a significant decrease as compared with that in control[（3 214.59±297.74） NU/mL, （3 260.62±229.44） NU/mL,vs（3 977.80＋309.09） NU/mL, P〈0.05], but there was no significant difference between them. Though they were still higher bhan those in Control group, pancreas destruction was slighter in PDTC group, iNOS expression and NF-κB p65 subunit mRNA expression were lower in PDTC group as compared with ANP group.CONCLUSION： We conclude that correlation among NF-κB activation, serum amylase, reactive oxygen species level and tissue damage suggests a key role of NF-κB in the pathogenesis of ANP. Inhibition of NF-κB activation may reverse the pancreatic damage of rat ANP and the production of reactive oxygen species.

Relaxin prevents the development of severe acute pancreatitis

AIM： TO investigate the severity of acute pancreatitis （AP） is associated to the intensity of leukocyte activation, inflammatory up-regulation and microcirculatory disruption associated to ischernia-reperfusion injury. Hicrovascular integrity and inhibition of pro-inflammatory mediators are key-factors in the evolution of AP. Relaxin is an insulin-like hormone that has been attributed vasorelaxant properties via the nitric oxide pathway while behaving as a glucocorticoid receptor agonist. METHODS： AP was induced by the bilio-pancreatic duct-outlet-exclusion closed-duodenal-loops model. Treatment with relaxin was done at different timepoints. Nitric oxide synthase inhibition by L-NAME and glucocorticoid receptor （GR） blockage by mifepristone was considered. AP severity was assessed by biochemical and histopathological analyses. RESULTS： Treatment with relaxin reduced serum amylase, lipase, C-reactive protein, IL-6, IL-10, hsp72, LDH and 8-isoprostane as well as pancreatic and lung myeloperoxidase. Acinar and fat necrosis, hemorrhage and neutrophil infiltrate were also decreased. ATP depletion and ADP/ATP ratio were reduced while caspases 2-3-8 and 9 activities were increased. L-NAME and mifepristone decreased the efficiency of relaxin. CONCLUSION： Relaxin resulted beneficial in the treatment of AP combining the properties of a GR agonist while preserving the microcirculation and favoring apoptosis over necrosis.

Application of endoscopic sphincterotomy in acute pancreatitis with fluid collection:A prospective study

AIM: To elucidate the role of endoscopic sphincterotomy (EST) in the treatment of acute pancreatitis. METHODS: Ninety patients with acute pancreatitis were randomly divided into two groups: EST group and control group. All the patients underwent pancreatitis routine therapy, additionally the EST group was treated with EST and endoscopic naso-bile drainage (ENBD).The time of disappearance of abdominal symptoms and signs,normalization of amylase, hospitalization and absorption of acute fluid was recorded for all patients.RESULTS: The time of disappearance of abdominal pain,normalization of blood and urine amylase and hospitalization was significantly shorter in EST group than in control group. The ratios of disappearance of fluid in mild acute pancreatitis patients was significantly higher in EST group (51.52%, 84.85%, 90.91%,93.94%) than in the control group (0%, 30.30%, 69.70%, 72.73%, P＜0.01 or P＜0.05).When the ratios of reduction of fluid in severe acute pancreatitis patients of the EST group were compared (8.33%, 58.33%, 83.33%, 91.67%) with those in the control group (0%, 8.33%, 25% and 41.67%), there were significant differences. CONCLUSION: The effect of EST+ENBD on acute pancreatitis with fluid is rather good.

Protective effect of fufanghuangqiduogan against acute liver injury in mice

AIM: To study the effects and possible mechanisms of fufanghuangqiduogan (FFHQ) in mice with acute liver injury (ALI). METHODS: ALI was successfully induced by injecting carbon tetrachloride (CCl4) intra peritoneally and by tail vein injection of Bacillus Calmette Guerin (BCG) and lipopolysaccharide (LPS) in mice, respectively. Each of the two model groups was divided into normal group, model group, FFHQ (60, 120 and 240 mg/kg) treatment groups, and bifendate treatment group. At the end of the experiment, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), content of malondialdehyde (MDA), activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) in liver homogenate were measured by biochemical methods. The activities of tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1) were determined by radio-immunoassay. Hepatic tissue sections were stained with hematoxylin and eosin and examined under a light microscope. RESULTS: In the two models of ALI, FFHQ (60, 120, 240 mg/kg) was found to significantly decrease the serum transaminase (ALT, AST) activities. Meanwhile, FFHQ decreased MDA contents and upregulated the lower SOD and GSH-px levels in liver homogenate. Furthermore, in immunologic liver injury model, FFHQ decreased levels of TNF-α and IL-1 in serum. Histologic examination showed that FFHQ could attenuate the area and extent of necrosis, reduce the immigration of inflammatory cells. CONCLUSION: FFHQ had protective effect on liver injury induced by either CCl4 or BCG+LPS in mice, and its mechanisms were related to free radical scavenging, increasing SOD and GSH-px activities and inhibiting the production of proinflammatory mediators.