柑橘黄龙病老龄果园发病力与时序发生规律研究

为揭示柑橘黄龙病自然感染年序病情发生规律,以提高监测预警防控水平提供科学依据,笔者于2002—2015年在天然隔离屏障良好的一个老龄果园开展柑橘黄龙病自然感染发病危害研究,在初入侵果园采取3个重复样地定点定株发病扩散危害系统调查。坚持14年试验结果表明:柑橘黄龙病自然感染发病力以自然感染发病4~5年后为最强盛,其发病力可达年新发病率10%~15%,较其初发病力增强2~3倍;其当年新发病率消长呈"M型"曲线变化规律:第1自然感染发病显症高峰一般为初次入侵后的第5年前后,峰期一般为2~3年;第2个自然感染发病显症高峰为初次入侵后的第9年前后,峰期一般为1~3年,两峰之间为高位波动变化动态。老龄果园黄龙病积年发病呈Logistic曲线上行变化轨迹,其年序数值化变化模型为Q=85.8144/(1+EXP(4.0063-0.5837N))(n=14,r=0.9941^(**)),其自然感染扩散大周期为15年(其中核心为害周期10年左右)。运用这些变化规律,对提升老龄果园黄龙病监测预警防控具有十分重要的指导意义。

Innate immunity in inflammatory bowel disease

The human intestinal tract is home to an enormous bacterial flora. The host defense against microorganisms can be divided into innate and adaptive immunity. The former is the most immediate line of response to immunologic challenges presented by bacteria, viruses, and fungi. The mucosal immune system has evolved to balance the need to respond to pathogens while co-existing with commensal bacteria and food antigens. In inflammatory bowel disease （IBD）, this hyporesponsiveness or tolerance breaks down and inflammation supervenes driven by the intestinal microbial flora. Bacteria contain compounds and are recognized by a variety of receptors, including Toll-like receptors （TLRs） and NODs （a family of intracellular bacterial sensors） and are potent stimuli of innate immune responses. Several mutations in these receptors have been associated with development of IBD.

Successful photodynamic therapy for biliary papillomatosis:A case report

Papillomatosis of the bile duct is a rare disease with a high risk of malignant transformation. Therapeutical options include partial hepatectomy and liver trans- plantation. A previously healthy 65-years old male developed jaundice and right upper abdominal quadrant pain in 1996. A villous adenoma of the distal bile duct was diagnosed. A Whipple procedure was performed. In 2002 the patient turned symptomatic again. An- other adenoma was found in the right hepatic duct resulting in a right hepatectomy. Two years later the patient again developed cholestasis. Alter drainage of the left hepatic duct with a percutaneous transhepatic cholangial drainage （PTCD） catheter, a recurrent biliary adenomatosis was diagnosed by cholangioscopy. As there was no surgical option left, the patient received photodynamic therapy （PDT） for the recurrent biliary papillomatosis. Three mo alter he received further photodynamic therapies, the bile duct epithelium appeared normal and the patient had no signs of adenomatosis, both macroscopically and histologically. The follow-up cholangioscopy in late 2005 revealed only a small papil-loma without the need for intervention. In early 2006, the patient died of multi organ failure without signs of extrahepatic cholestasis or cholangitis at the age of 75, 10 years after the diagnosis of biliary papillomatosis was established. The patient exceeded the average life expectancy of patients with biliary papillomatosis by far. Thus, PDT might be a sufficient therapeutic option for recurrent papillomatosis patients with no significant side effects.

Investigation of the effect of military stress on the prevalence of functional bowel disorders

AIM: To investigate the morbidity of functional bowel disorders (FBD) under military stress conditions in order to lay foundations for the prevention and treatment of this disease. METHODS: Four hundred and fifty-seven soldiers who were assigned to specified services and 471 soldiers who were assigned to routine services were enrolled using cluster sampling, with the latter as a control group. They were surveyed using the Rome Ⅲ FBD standard questionnaire. The FBD symptom question-naire included FBD-related symptoms, severity, dura- tion or attack time, and accompanying symptoms. RESULTS: The morbidity of the military stress group (14.6%) was significantly higher than in the control group (9.98%) ( 2 = 4.585, P < 0.05). The incidence of smoking, abdominal pain and acid regurgitation ( 2 = 4.761, P < 0.05) as well as the ZUNG anxiety/depression scores ( 2 = 7.982, P < 0.01) were also sig- nificantly higher in the military stress group compared with the control group. ZUNG anxiety ( 2 = 11.523, P < 0.01) and depression ( 2 = 5.149, P < 0.05) scores were higher in the FBD group compared with the non-FBD group. The differences in the ZUNG self-rated anxiety and depression scales between the 2 groups were statistically significant ( 2 = 14.482, P < 0.01 and 2 = 6.176, P < 0.05). CONCLUSION: The morbidity of FBD was higher under military stress conditions.

Global and Regional Trends and Projections of Infective Endocarditis-Associated Disease Burden and Attributable Risk Factors from 1990 to 2030

Objective To forecast the future burden and its attributable risk factors of infective endocarditis(IE).Methods We analyzed the disease burden of IE and its risk factors from 1990 to 2019 using the Global Burden of Disease 2019 database and projected the disease burden from 2020 to 2030 using a Bayesian age-period-cohort model.Results By 2030,the incidence of IE will increase uncontrollably on a global scale,with developed countries having the largest number of cases and developing countries experiencing the fastest growth.The affected population will be predominantly males,but the gender gap will narrow.The elderly in high-income countries will bear the greatest burden,with a gradual shift to middle-income countries.The incidence of IE in countries with middle/high-middle social-demographic indicators(SDI) will surpass that of high SDI countries.In China,the incidence rate and the number of IE will reach 18.07 per 100,000 and 451,596 in 2030,respectively.IEassociated deaths and heart failure will continue to impose a significant burden on society,the burden on women will increase and surpass that on men,and the elderly in high-SDI countries will bear the heaviest burden.High systolic blood pressure has become the primary risk factor for IE-related death.Conclusions This study provides comprehensive analyses of the disease burden and risk factors of IE worldwide over the next decade.The IE-associated incidence will increase in the future and the death and heart failure burden will not be appropriately controlled.Gender,age,regional,and country heterogeneity should be taken seriously to facilitate in making effective strategies for lowering the IE disease burden.

MHD from a Microscopic Concept and Onset of Turbulence in Hartmann Flow

We derive higher order magneto-hydrodynamic （MHD） equations from a microscopic picture using pro-jection and perturbation formalism. In an application to Hartmann flow we find velocity profiles flattening towards the center at the onset of turbulence in hydrodynamic limit. Comparison with the system under the effect of a uniform magnetic field yields difference in the onset of turbulence consistent with observations, showing that the presence of magnetic field inhibits onset of instability or turbulence. The laminar-turbulent transition is demonstrated in a phase transition plot of the development in time of the relative average velocities vs. Reynolds number showing a sharp increase of the relative average velocity at the transition point as determined by the critical Reynolds number.

An Overview of the Highly Pathogenic H5N1 Influenza Virus

Since the first human case of H5N1 avian influenza virus infection was reported in 1997, this highly pathogenic virus has infected hundreds of people around the world and resulted in many deaths. The ability of H5N1 to cross species boundaries, and the presence of polymorphisms that enhance virulence, present challenges to developing clear strategies to prevent the pandemic spread of this highly pathogenic avian influenza (HPAI) virus. This review summarizes the current understanding of, and recent research on, the avian influenza H5N1 virus, including transmission, virulence, pathogenesis, clinical characteristics, treatment and prevention.

Long-term survival following heart transplantation is possible

Objective:To determine whether long-term survival(>10 years) after heart transplantation is possible and identify complications influencing long-term survival.Methods:We analyzed clinical outcomes in the group of 21 patients who had undergone heart transplantation at the Second Affiliated Hospital of Harbin Medical University since 1992 and 4 of them survived more than 10 years.Results:Nine patients are still alive with normal left ventricular function,and 4 of them have survived more than 10 years.The longest survival patient has lived more than 18 years after transplantation,whose survival is the longest in China and in Asia.We have also found that there has been a high incidence of complications,such as rejection episodes during the first 6 months,and transplant vasculopathy in the long-term survival patients.Conclusion:Long-term survivors maintain normal hemodynamic function of their allografts,and long-term survival following cardiac transplantation is possible.Aggressive preventive and therapeutic measures are essential to limit the risk factors for development of complications such as rejection episodes and transplant vasculopathy,and enable long-term survival after cardiac transplantation.

Stress-induced intestinal necrosis resulting from severe trauma of an earthquake

AIM:To investigate the possible reasons and suggest therapeutic plan of stress-induced intestinal necrosis resulting from the severe trauma.METHODS:Three patients in our study were trapped inside collapsed structures for 22,21 and 37 h,respectively,The patients underwent 3-4 operations after sustaining their injuries,Mechanical ventilation,intermittent hemodialysis and other treatments were also provided.The patients showed signs of peritoneal irritation on postoperative days 10-38.Small intestinal necrosis was confirmed by emergency laparotomy,and for each patient,part of the small bowel was removed.RESULTS:Two patients who all performed 3 operations died of respiratory complications on the first and second postoperative days respectively.The third patient who performed 4 operations was discharged and made a full recovery.Three patients had the following common characteristics:(1) Multiple severe trauma events with no direct penetrating gastrointestinal injury;(2) Multiple surgeries with impaired renal function and intermittent hemodialysis treatment;(3) Progressive abdominal pain and tenderness,and peritoneal irritation was present on post-traumatic days 10-38;(4) Abdominal operations confirmed segment ulcer,necrosis of the small intestine,hyperplasia and stiffness of the intestinal wall;and(5) Pathological examinations suggested submucosal hemorrhage,necrosis,fibrosis and hyalinization of the vascular wall.Pathological examinations of all 3 patients suggested intestinal necrosis with fistulas.CONCLUSION:Intestinal necrosis is strongly associated with stress from trauma and post-traumatic complications;timely exploratory laparotomy maybe an effective method for preventing and treating stressinduced intestinal necrosis.

Research advancement in immunopathogenesis of myasthenia gravis

Myasthenia gravis （MG） is an autoimmune neuromuscular junction disease mediated by antibodies against the acetylcholine receptor （AChR）. The etiology and immunopathogenesis of MG remain unclear. Recent research has shown the involvement of autoantibodies, lymphocytes, cytokines and chemokines, in the pathogenesis of MG. Systematic factors are also demonstrated, such as inheritance and endocrine. This review indicates the research development in immunopathogenesis of MG.

Roles of forced and inertially unstable convection development in the onset process of Indian summer monsoon

The NCEP/NCAR R1 reanalysis data are employed to investigate the impact of forced and inertial instability in the lower troposphere over the Arabian Sea on the onset process of Indian summer monsoon(ISM),and to reveal the important role of zonal advection of zonal geostrophic momentum played in the forced unstable convection.Results show that during the ISM onset the zero absolute vorticity contour(??=0)shifts northward due to the strong cross-equatorial pressure gradient in the lower troposphere over southern Arabian Sea.Thus a region with negative absolute vorticity is generated near the equator in the northern hemisphere,manifesting the evident free inertial instability.When a southerly passes through this region,under the influence of friction a lower convergence that facilitates the convection flourishing at the lower latitudes appears to the north of zero absolute vorticity contour.However,owing to such a traditional inertial instability,the convection is confined near the equator which does not have direct influence on the ISM onset.On the contrary in the region to the north of the zero absolute vorticity contour and to the south of the low pressure center near the surface,although the atmosphere there is inertially stable,the lower westerly jet can develop and bring on the apparent zonal advection of zonal geostrophic momentum.Both theoretical study and diagnosing analysis present that such a zonal advection of geostrophic momentum is closely associated with the zonal asymmetric distribution of meridional land-sea thermal contrast,which induces a convergence center near and further north of the westerly jet in the lower troposphere over the southwestern coast of the Indian Peninsula,providing a favorable lower circulation for the ISM onset.It illustrates that the development of convection over the Arabian Sea in late spring and early summer is not only due to the frictional inertial instability but also strongly affected by the zonal asymmetric distribution of land-sea thermal contrast.Moreover,before the ISM onset due to the eastward development of the South Asian High(SAH)in the upper troposphere,high potential vorticity is transported to the region over the Arabian Sea.Then a local trumpet-shaped stream field is generated to cause the evident upper divergence-pumping effect which favors the ISM onset.When the upper divergence is vertically coupled with the lower convergence resulted from the aforementioned forced unstable convection development near the southwestern coast of Indian Peninsula,the atmospheric baroclinic unstable development is stimulated and the ISM onset is triggered.

DYNAMICS OF SIS EPIDEMIC MODEL WITH THE STANDARD INCIDENCE RATE AND SATURATED TREATMENT FUNCTION

An SIS epidemic model with the standard incidence rate and saturated treatment func- tion is proposed. The dynamics of the system are discussed, and the effect of the capacity for treatment and the recruitment of the population are also studied. We find that the effect of the maximum recovery per unit of time and the recruitment rate of the popula- tion over some level are two factors which lead to the backward bifurcation, and in some cases, the model may undergo the saddle-node bifurcation or Bogdanov-Takens bifurca- tion. It is shown that the disease-free equilibrium is globally asymptotically stable under some conditions, Numerical simulations are consistent with our obtained results in the- orems, which show that improving the efficiency and capacity of treatment is important for control of disease.

Mathematical modeling approach to the transmission dynamics of pine wilt disease with saturated incidence rate

The present paper investigates the dynamics of pine wilt disease with saturated incidence rate. The proposed model is stable both locally and globally. The local stability of the disease-free equilibrium is determined by the basic reproduction R0. The disease-free equilibrium is stable locally and globally whenever R0〈 1. If R0 〉 1, then the endemic state is stable both locally and globally. Further, a brief discussion with conclusion on the numerical results of the proposed model is presented.

The roles of ebolavirus glycoproteins in viral pathogenesis

Ebolaviruses are highly dangerous pathogens exhibiting extreme virulence in humans and nonhuman primates. The majority of ebolavirus species, most notably Zaire ebolavirus, can cause Ebola virus disease(EVD), formerly known as Ebola hemorrhagic fever, in humans. EVD is associated with case-fatality rates as high as 90%, and there is currently no specific treatment or licensed vaccine available against EVD. Understanding the molecular biology and pathogenesis of ebolaviruses is important for the development of antiviral therapeutics. Ebolavirus encodes several forms of glycoproteins(GPs), which have some interesting characteristics, including the transcriptional editing coding strategy and extensive O-glycosylation modification, clustered in the mucin-like domain of GP1, full-length GP(GP_(1,2)), and shed GP. In addition to the canonical role of the spike protein, GP_(1,2), in viral entry, ebolavirus GPs appear to have multiple additional functions,likely contributing to the complex pathogenesis of the virus. Here, we review the roles of ebolavirus GPs in viral pathogenesis.

Dynamics of SVEIS epidemic model with distinct incidence

In this paper, we study the global dynamics of a SVEIS epidemic model with distinct incidence for exposed and infectives. The model is analyzed for stability and bifurcation behavior. To account for the realistic phenomenon of non-homogeneous mixing, the effect of diffusion on different population subclasses is considered. The diffusive model is analyzed using matrix stability theory and conditions for Turing bifurcation are derived. Numerical simulations support our analytical results on the dynamic behavior of tile model.

Global dynamics of a heroin epidemic model with age structure and nonlinear incidence

A heroin model with nonlinear incidence rate and age structure is investigated. The basic reproduction number is determined whether or not a heroin epidemic breaks out. By employing the Lyapunov functionals, the drug-free equilibrium is globally asymptotically stable if R0 ≤1; while the drug spread equilibrium is also globally asymptotically stable if R0≤ 1. Our results imply that improving detected rates and drawing up the efficient prevention play more important role than increasing the treatment for drug users.

VIRAL DYNAMICS IN A DISTRIBUTED TIME DELAYED HCV PATHOGENESIS MODEL

In this paper, we investigate global dynamics for a distributed time delayed HCV infec tion model. Our model admits two possible equilibria, an uninfected equilibrium and infected equilibrium depending on the basic reproduction number. By employing the method of Lyapunov functional, we prove that the uninfected equilibrium is global asymptotically stable if the basic reproduction number is less than one, it is unsta ble and the infected equilibrium is global asymptotically stable if the basic reproduction number is larger than one. The simulations results are in good accordance with our analytic results.

Effect of Winglet Geometry Arrangement and Incidence on Tip Clearance Control in a Compressor Cascade

An experimental study is conducted to investigate the influences of blade tip winglet on the flow field of a compressor cascade. The tests are performed in a low speed linear cascade with stationary endwall, with three blade tip configurations, including the baseline tip, the suction-side winglet tip and the pressure-side winglet tip. The fiowfield downstream of the cascade is measured using five-hole probe, from which the three-dimensional velocity field, vorticity field and pressure field are obtained. Static pressure measurements are made on the endwall above the blade row using pressure taps embedded in the plywood endwall. All measurements are made at both design and off-design conditions for tip clearance level of about 2 percent of the blade chord. The results revealed the incidence variation significantly affects the secondary flow and the associated loss field downstream of the cascade, where the tip leakage vortex and passage vortex exist as the major contributors on the field. The winglet geometry arrangements can change the trajectory of the tip leakage vortex. The suction-side winglet tip blade provides a lower overall total pressure loss coefficient when compared to the baseline tip blade and pressure-side winglet tip blade at all incidence angles.