جستجوی مقالات مرتبط با کلیدواژه « conjugate » در نشریات گروه « پزشکی »

 Pseudomonas aeruginosa is an opportunistic pathogen, and alginate is its most important factor in pathogenicity. The objective of the study is the immunogenicity evaluation of P. Pseudomonas aeruginosa alginate conjugated to exotoxin A as a vaccine candidate in mice.

 The mucoid strain of Pseudomonas aeruginosa 6494 was used to prepare alginate, and the separation of exotoxin A was done with the standard strain of PAO1. Alginate was extracted by means of sedimentation with cold ethanol, dialysis, enzymatic digestion and chromatography. To improve immunogenicity, purified antigen was coupled to exotoxin A with ADH as a spacer and EDAC as a linker. Based on confirmation tests, the resulting conjugate was devoid of specific toxicity and pyrogenic effect. Four groups of BALB/c female mice (each group was included 15 mice) were selected in the next step. The first group with the ALG, the second group with the D-ALG-ETA, and the third one with the ETA were vaccinated. The fourth group (control group) was vaccinated with normal saline. Vaccination was performed in three injectable doses with two-week intervals. Subsequently, serum samples were collected, and antibody responses were measured by the ELISA method for total IgG, IgG1, IgG2a, IgG2b, IgG3.

 After the second and third doses with ALG-ETA showed a significant increase in antibody titer against ALG-ETA in comparison with pure ALG. The titers of IgG2a, IgG2b, IgG, IgG1, IgG3 antibodies that produced against alginate increased in the third injection compared to the first conjugate injection, which was 2.9, 3, 5.2, 10, and 9.2, respectively.

 These results show that ALG from Pseudomonas aeruginosa increases anti-alginate antibodies in conjugate form with exotoxin A and can be considered an appropriate, effective adjuvant.

The Haemophilus influenzae type b (Hib) infection is a leading cause of meningitis in infants and children in the developing countries, estimated that at least three million serious cases of disease worldwide are caused by Hib each year. The capsular of Hib, is the most important cause of its virulence. The capsular polysaccharide conjugated to a carrier protein is effective in the prevention of such infections. The routine vaccination against Hib has not been defined in the national immunization program of Iran. The aim of this study was to achieve an efficient method for producing vaccines against meningitis caused by haemophilus influenzae.
In this study, a derivative of Hib Polysaccharide (PRP) was conjugated to outer membrane vesicle (OMV) of Niesseria meningitides group B by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC). Two methods, involving adipic acid dihydrazide (ADH) as a linker, were used. The polysaccharide activated with cyanogen bromide (CNBr) and EDAC separately. The first, ADH was bounded to PRP activated with CNBr to form PRPCNBr AH, second ADH was bounded to PRP activated with EDAC to form PRPEDAC AH. These derivatives were bound to OMV by EDAC to form PRPCNBr AH-OMV and PRPEDAC AH-OMV.
On the basis of the bounded protein to polysaccharide, the yield of conjugated PRPCNBr AH-OMV and PRPEDAC AH-OMV were calculated 63.3% and 47%, respectively.
The results indicated that average yield of conjugation with CNBr activator was higher than other activators, however more study required to other methods and comparing them together to achieve an effective conjugated vaccine.

Background and In recent years, the incidence of cancers has increased in the world. Therefore, many researches have focused on new strategies for treatment of cancers. Previous studies showed that quinolone antibacterials can inhibit human topoisomerases at high concentrations and can be considered as potential cytotoxic agents. On the other hand, 5,7-dibromoisatin is a cytotoxic agent and inhibits tubulin polymerization. Accordingly, a series of ciprofloxacin-isatin conjugates were prepared as potential cytotoxic agents.
Isatin was dibrominated by bromine in refluxing ethanol. The 5,7-dibromoisatin was reacted with ciprofloxacin in the presence of paraformaldehyde to produce N-Mannich base of ciprofloxacin. Furthermore, 5,7-dibromoisatin was reacted with 1-bromo-2-chloroethane to give N-(2-chloroethyl)-5,7-dibromoisatin. The latter compound was reacted with ciprofloxacin to afford related conjugate analog containing two carbons linker. All compounds were purified by extraction and crystallization. The structures of compounds were assigned by IR and NMR spectroscopy.
Conveniently, several new conjugates of ciprofloxacin and isatin containing methylene or ethylene linker were prepared. The isolated yields for final compounds were 23 to 34%. In the preparation of final compounds with methylene linker (compounds 4a and 4b), ethanol was found to be the best solvent while N,N-dimethylformamide (DMF) was an appropriate solvent for preparation of compound 4c, bearing an ethylene linker. The final products were re-crystallized from DMF or DMF-water.
The conjugate analogs of ciprofloxacin and isatin derivatives can be obtained using an appropriate and convenient method. The designed compounds have both pharmacophoric motifs of quinolones and isatin and potentially can be considered as new cytotoxic agents.

Polysaccharide vaccines are effective in individuals from about the two years of age but, as they elicit T-cell independent immunity, they are not effective in younger children. In contrast, polysaccharide-protein conjugates are shown to be highly immunogenic in infants and induce T-cell dependent immunity. In this study, capsular polysaccharide of Neisseria meningitidis type A (NMA-CPS) was attached to recombinant protein of hepatitis B surface antigen (rHbsAg) covalently using amidation method. Immunization was done, choosing 2 groups of rabbits. Pure NMA-CPS and conjugated molecule were injected to groups 1 and 2, with a 15-day interval, intramuscularly. The bleeding was performed at days 0, 15, 30, 45 and titers of sera were measured via serum bactericidal assay. Polysaccharide bactericidal titer on days 15, 30 and 45 was almost identical and there was no increase in titer. But, in the first injection of the conjugate, the titer was much more (about twice of purified polysaccharide), and in the second injection, increased. Results display that conjugated molecules cause more immunity than pure capsular polysaccharide, and can stimulate cellular immunity.

Lysozyme is a natural enzyme with positive antimicrobial activity against Gram Positive bacteria، but its action is limited on Gram Negative bacteria، which is assumed a restriction for its uses in industry. The purpose of this research was to glycosylate lysozyme with dextran through Maillard-based reaction and to study the antimicrobial characteristics of lysozyme-dextran conjugate. Glycosylation of lysozyme with dextran was performed using a 1:5 weight ratio of protein to dextran، incubated at 60 MC for one week under the relative humidity of 79%. For evaluating conjugation of dextran to lysozyme، SDS-PAGE electrophoresis was conducted. Gel filtration chromatography with sephadox G-100 was used for separation of conjugated enzyme. Lytic activity، free amino group and antimicrobial activity of the modified enzyme were evaluated. SDS-PAGE electrophoresis was used to follow the glycosylation process. Results indicated that 3. 7 moles of dextran were coupled to one mole of lysozyme. The lytic activity of the conjugate was about 62% of that of the native lysozyme. Evaluation of antimicrobial activity of the lysozymedextran conjugate، indicated the effectiveness of modified enzyme against E. coli and a progressive increase in antimicrobial activity with an increase in enzyme-conjugate concentration. The antimicrobial action of lysozyme on S. aureus was not improved by conjugation with dextran as compared with that of E. coli. These results might increase the application of lysozyme as a natural antimicrobial ingredient in different food systems.