Protection against pneumococcal infection in mice conferred by phosphocholine-binding antibodies: specificity of the phosphocholine binding and relation to several types.

Some anti-phosphocholine antibodies protect mice against challenge with certain, but not all, pneumococcal types. We found that both their isotype and reactivity with the cell wall C-polysaccharide of encapsulated pneumococci, as measured by immunodiffusion, were important in predicting the protective activity of anti-phosphocholine antibodies. We propose that the specificity of the protective antibodies includes the backbone of the phosphocholine-containing structure.     

Hydrolytic stability of pneumococcal group 6 (type 6A and 6B) capsular polysaccharides.

The hydrolyses of the immunologically cross-reactive and constitutionally isomeric group 6 pneumococcal polysaccharides, types 6A and 6B, were investigated by 31P nuclear magnetic resonance spectroscopy, gel filtration through Sepharose 4B, reducing-sugar analysis, and rocket immunoelectrophoresis. Phosphorus nuclear magnetic resonance spectroscopy showed that cleavage of the repeating-unit phosphodiester linkages at pH 10, 60 degrees C was considerably faster (greater than 10(3) ) for the type 6A than the type 6B polysaccharide. Under these reaction conditions, 31P nuclear magnetic resonance kinetic measurements showed that the Na+ form of the type 6A polysaccharide underwent phosphodiester-linkage hydrolysis two times slower than the corresponding Ca+2 form; a stoichiometrically excess amount of Ca+2 caused a 30-fold enhancement of the latter hydrolysis rate. The spectroscopic characterization of phosphorus-containing end groups resulting from hydrolysis of the type 6A polymer provided additional mechanistic information. Heating the type 6A and 6B polysaccharides at 56 degrees C for various times led to gel filtration coefficients of distribution (Kd values) which indicated that the type 6A material underwent size reductions considerably faster than did the type 6B antigen; these increased Kd values qualitatively correlated with the loss of immunochemical reactivity measured by rocket immunoelectrophoresis. The application of a statistical theory to the depolymerization of the type 6A and 6B polysaccharides was consistent with random bond cleavage, as evidenced by the calculated versus measured gel filtration patterns. Although the molecular changes causing the size reductions were not fully elaborated, it was established that the acetal linkages of the type 6A and 6B polysaccharides were comparatively resistant to hydrolysis and that depolymerization by hydrolysis of the phosphodiester linkage was a major factor only in the type 6A structure. It was concluded that the hydrolytic stability of the type 6B antigen would favor its use in the polyvalent pneumococcal vaccine rather than the cross-reactive, but comparatively unstable, type 6A polysaccharide, if all other factors are equal.     

Synthesis and physicochemical and immunological characterization of pneumococcus type 12F polysaccharide-diphtheria toxoid conjugates.

A scheme for the synthesis and purification of conjugates, composed of the type 12F capsular polysaccharide of Streptococcus pneumoniae (Pn12F) and diphtheria toxoid, is described. The scheme is a modification of that described previously for the Vi capsular polysaccharide of Salmonella typhi, a linear homopolymer of N-acetylgalactoseaminouronic acid (S. C. Szu, A. L. Stone, J. D. Robbins, R. Schneerson, and J. B. Robbins, J. Exp. Med. 166:1510-1524, 1986). Pn12F is a branched-chain copolymer composed of a hexasaccharide repeating unit containing an aminouronic acid, N-acetylmannoseaminouronic acid (K. Leontein, B. Lindberg, and J. Lonngren, Can. J. Chem. 59:2081-2085, 1981). Sulfhydryl groups were introduced into Pn12F by forming an amide bond between cystamine and carboxyl groups of N-acetylmannoseaminouronic acid in the presence of a carbodiimide. The disulfide moiety of cystamine was reduced to form the cysteamine derivative of Pn12F which was, in turn, covalently bound to diphtheria toxoid by using the heterobifunctional linker N-succinimidyl-3-(2-pyridylthio)propionate. Unbound, high-molecular-weight Pn12F was removed from the conjugate by hydrophobic interaction chromatography through octyl Sepharose by using n-octyl-beta-D-glucopyranoside as the eluent. In young outbred mice, Pn12F did not elicit detectable serum antibodies. Pn12F-diphtheria toxoid, in contrast, elicited antibodies after two injections and had T-cell-dependent properties as evidenced by a response to priming and by its ability to elicit booster responses. This scheme seems applicable to the synthesis of conjugates with other capsular polysaccharides containing aminouronic acids. Clinical evaluation of Pn12F-diphtheria toxoid conjugates in healthy and in immunocompromised hosts is planned.     

Effect of dosage on immunogenicity of a Vi conjugate vaccine injected twice into 2- to 5-year-old Vietnamese children

In a double-blind, randomized, and placebo-controlled previous trial, the efficacy of Vi-rEPA for typhoid fever in 2- to 5-year-olds was 89.0% for 46 months. Vi-rEPA contained 25 microg of Vi and induced a greater-than-eightfold rise in immunoglobulin G (IgG) anti-Vi in all of the vaccinees tested. In this investigation, we conducted a dosage-immunogenicity study of 5, 12.5, and 25 microg of Vi-rEPA in this age group. Two doses of Vi-rEPA were injected 6 weeks apart. Blood samples were taken before and at 10 weeks (4 weeks after the second injection) and 1 year later. All postimmunization geometric mean (GM) levels were higher than the preimmune levels (P < 0.0001). At 10 weeks, the GM IgG anti-Vi level elicited by 25 microg (102 EU/ml) was higher than those elicited by 12.5 microg (74.7 EU/ml) and 5 microg (43 EU/ml) (P < 0.004): all of the children had > or = 3.52 EU/ml (estimated minimum protective level). One year later, the levels declined about sevenfold (13.3 and 11.3 versus 6.43 EU/ml, P < 0.0001) but remained significantly higher than the preimmune levels (P < 0.0001), and >96% of the children had a greater-than-eightfold rise. This study also confirmed the safety and consistent immunogenicity of the four lots of Vi-rEPA used in this and previous trials.     

Synthesis and immunologic properties in mice of vaccines composed of Staphylococcus aureus type 5 and type 8 capsular polysaccharides conjugated to Pseudomonas aeruginosa exotoxin A.

Epidemiological, serological and in vitro phagocytosis experiments provide evidence that the newly discovered type 5 and type 8 capsular polysaccharides (CPs) are both virulence factors and protective antigens for bacteremia caused by Staphylococcus aureus. Neither type 5 nor type 8 CP elicited serum antibodies when injected into mice. These two CPs were bound to Pseudomonas aeruginosa exotoxin A (ETA) to form conjugates by using the synthetic scheme devised for the CP (Vi) of Salmonella typhi and of pneumococcus type 12F (A. Fattom, W. F. Vann, S. C. Szu, A. Sutton, X. Li, D. Bryla, G. Schiffman, J. B. Robbins, and R. Schneerson, Infect. Immun. 56:2292-2298, 1988; S. C. Szu, A. L. Stone, J. D. Robbins, R. Schneerson, and J. B. Robbins, J. Exp. Med. 166:1510-1524, 1987). Both S. aureus CP-ETA conjugates elicited a rise in CP antibodies. As components of conjugates, both S. aureus CPs acquired T-cell-dependent properties, as shown by their ability to respond to carrier priming and to stimulate booster responses. The conjugate-induced antibodies facilitated type-specific opsonization of S. aureus by human polymorphonuclear leukocytes. The conjugates also induced ETA antibodies which neutralized the native toxin in vitro. Clinical studies of these two conjugates for active or passive immunization of patients at risk for S. aureus bacteremia are planned.     

Hyaluronic acid‐dependent protection against UVB‐damaged human corneal cells

Within ultraviolet radiation, ultraviolet B (UVB) is the most energetic and damaging to humans. At the protein level, UVB irradiation downregulates the expression of antioxidant enzymes leading to the accumulation of reactive oxygen species (ROS). Due to lacking of a global analysis of UVB‐modulated corneal proteome, we investigate in vitro the mechanism of UVB‐induced corneal damage to determine whether hyaluronic acid (HA) is able to reduce UVB irradiation‐induced injury in human corneal epithelial cells. Accordingly, human corneal epithelial cell lines (HCE‐2) were irradiated with UVB, followed by incubation with low molecular weight HA (LMW‐HA, 100 kDa) or high molecular weight HA (HMW‐HA, 1,000 kDa) to investigate the physiologic protection of HMW‐HA in UVB‐induced corneal injury, and to perform a global proteomic analysis. The data demonstrated that HA treatment protects corneal epithelial cells in the UVB‐induced wound model, and that the molecular weight of HA is a crucial factor. Only HMW‐HA significantly reduces the UVB‐induced cytotoxic effects in corneal cells and increases cell migration and wound‐healing ability. In addition, proteomic analysis showed that HMW‐HA might modulate cytoskeleton regulation, signal transduction, biosynthesis, redox regulation, and protein folding to stimulate wound healing and to prevent these UVB‐damaged cells from cell death. Further studies evidenced membrane‐associated progesterone receptor component 1 (mPR) and malate dehydrogenase (MDH2) play essential roles in protecting corneal cells from UVB irradiation. This study reports on UVB‐modulated cellular proteins that might play an important role in UVB‐induced corneal cell injury and show HMW‐HA to be a potential substance for protecting corneal cells from UVB‐induced injury. Environ. Mol. Mutagen. 54:429–449, 2013. © 2013 Wiley Periodicals, Inc.     

Reduced clot permeability and susceptibility to lysis in patients with acute coronary syndrome: effects of inflammation and oxidative stress

BackgroundStable angina is associated with unfavorable fibrin structure/function. It is not known how acute coronary syndromes (ACS) affect fibrin architecture.ObjectiveWe investigated fibrin clot properties and their determinants in ACS patients.Patients and methodsClot permeability, turbidity and fibrinolysis were assessed in 40 patients with ACS versus 40 controls with stable angina matched for age, sex, and risk factors.ResultsPatients with ACS had lower clot permeability (p = 0.001), faster fibrin polymerization (p = 0.008), and prolonged fibrinolysis time (p < 0.0001) than controls. C-reactive protein (CRP) and 8-epi-prostaglandin F_2α, a marker of oxidative stress, were the only independent predictors of clot permeability (R² = ?0.74; p < 0.0001 and R² = ?0.65; p < 0.0001, respectively) and fibrinolysis time in ACS patients (R² = 0.60; p < 0.0001 and R² = 0.59; p = 0.0002, respectively). In angina patients, fibrinogen and CRP predicted permeability (R² = ?0.71; p < 0.0001 and R² = ?0.62; p < 0.0001), and D-dimer predicted lysis time (R² = 0.54; p = 0.0005). In regression analysis models incorporating all patients, the only independent predictor of all clot variables was being an ACS patient (R² 0.51 to 0.85; p < 0.001).ConclusionsThis first study of clot properties in patients during an ACS demonstrated that compared with stable angina patients, their clots are composed of dense networks that are more resistant to lysis and these features are correlated with raised CRP and oxidative stress.     

泮托拉唑对比奥美拉唑治疗胃溃疡的成本效果分析

目的：运用药物经济学方法研究和评价泮托拉唑对比奥美拉唑治疗胃溃疡的成本效果,为临床合理用药提供参考和建议。方法：立足医疗系统研究视角,构建决策树模型对泮托拉唑和奥美拉唑治疗胃溃疡进行成本效果分析,并对参数的不确定性进行单因素敏感性分析。结果：从平均成本效果比来看,泮托拉唑治疗胃溃疡平均每单位效果的成本为33.36元,奥美拉唑为21.18元;增量成本效果分析显示,泮托拉唑相对于奥美拉唑的增量成本效果比为131.14（ICER=131.14）,增加单位治愈病例意愿支付金额小于131.14元时,最优方案为奥美拉唑,意愿支付金额大于131.14元时,最优方案为泮托拉唑。结论：临床医生可以根据胃溃疡患者意愿支付金额高低选择最优的治疗方案。