Production of Single-Chain Fv Antibodies Specific for GA-Pyridine, an Advanced Glycation End-Product (AGE), with Reduced Inter-Domain Motion.

Due to their lower production cost compared with monoclonal antibodies, single-chain variable fragments (scFvs) have potential for use in several applications, such as for diagnosis and treatment of a range of diseases, and as sensor elements. However, the usefulness of scFvs is limited by inhomogeneity through the formation of dimers, trimers, and larger oligomers. The scFv protein is assumed to be in equilibrium between the closed and open states formed by assembly or disassembly of VH and VL domains. Therefore, the production of an scFv with equilibrium biased to the closed state would be critical to overcome the problem in inhomogeneity of scFv for industrial or therapeutic applications. In this study, we obtained scFv clones stable against GA-pyridine, an advanced glycation end-product (AGE), by using a combination of a phage display system and random mutagenesis. Executing the bio-panning at 37 °C markedly improved the stability of scFvs. We further evaluated the radius of gyration by small-angle X-ray scattering (SAXS), obtained compact clones, and also visualized open.

Inhibition of corneal neovascularization with plasmid pigment epithelium-derived factor (p-PEDF) delivered by synthetic amphiphile INTeraction-18 (SAINT-18) vector in an experimental model of rat corneal angiogenesis.

The use of Synthetic Amphiphile INTeraction-18 (SAINT-18) carrying plasmid pigment epithelium-derived factor (p-PEDF) as an anti-angiogenesis strategy to treat corneal neovascularization in a rat model was evaluated. Four partially dried forms (Group A: 0 microg, B: 0.1 microg, C: 1 microg, D: 10 microg) of a p-PEDF-SAINT-18 were prepared and implanted into the rat subconjunctival substantia propria 1.5 mm from the limbus at the temporal side. The 1 microg of plasmid-basic fibroblast growth factor--SAINT-18 (p-bFGF-SAINT-18) (1 microg) was prepared and implanted into the rat corneal stroma 1.5 mm from the limbus on the same side. Inhibition of neovascularization was observed and quantified from day 1 to day 60. PEDF (50-kDa) and bFGF (18-kDa) protein expression were analyzed by biomicroscopic examination, Western blot analysis, and immunohistochemistry. Gene expression in corneal and conjunctival tissue was observed as early as 3 days after gene transfer and stably lasted for over 3 months with minimal immune reaction. Subconjunctival injection of a highly efficient p-PEDF-SAINT-18 successfully inhibited corneal neovascularization. Successful gene expression of bFGF, PEDF and a mild immune response of HLA-DR were shown by immunohistochemistry staining. We concluded that SAINT-18 was capable of directly delivering genes to the ocular surface by way of subconjunctival injection, and delivered sustained, high levels of gene expression in vivo to inhibit angiogenesis.

Cardiac functional and structural alterations induced by endotoxin in rats: importance of platelet-activating factor.

OBJECTIVE: In this study, we evaluated the time course of the alterations in left ventricular (LV) dimensions, LV wall thickness, and LV systolic function in rats with endotoxemia by using echocardiography as well as myocardial histopathologic assessments. Our second goal was to examine whether pretreatment with a platelet-activating factor (PAF) antagonist would ameliorate the lipopolysaccharide (LPS)-induced cardiovascular collapse during the early phase. DESIGN: A prospective, controlled, in vivo animal laboratory study. SETTING: Research laboratory at a university. SUBJECTS: Male, Wistar rats (8-9 wks old; n = 83). INTERVENTIONS: In pentobarbital-anesthetized rats, the right carotid artery was cannulated to measure the arterial blood pressure and to sample blood. The right jugular vein also was catheterized for the administration of drugs. LPS (2 mg/kg) derived from Klebsiella pneumoniae or physiologic saline was administered in the presence or absence of pretreatment with TCV-309, a specific potent PAF antagonist. Echocardiographic studies were performed with an 8- to 13-MHz transducer. MEASUREMENTS AND MAIN RESULTS: LPS administration immediately induced progressive hypotension. The maximal hypotensive response was observed at 10 mins after LPS infusion with mean arterial pressure decreasing from 119 +/- 2 to 56 +/- 3 mm Hg (p < .001). LV end-diastolic internal dimensions decreased from 6.4 +/- 0.1 to 3.1 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced compared with control rats. LV end-systolic dimensions also decreased dramatically from 3.5 +/- 0.2 to 0.5 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced throughout the experiment. LV fractional shortening increased from 45 +/- 1% to 84 +/- 2% (p < .001) at 30 mins after LPS and remained elevated compared with control rats. LV wall thickness increased strikingly from 15 mins until 2 hrs after LPS infusion. Pathologic studies demonstrated marked congestion of capillaries and mild edema in the LV myocardium. The hematocrit increased after the administration of LPS. LPS markedly increased sympathetic tone as demonstrated by the elevation of plasma concentrations of epinephrine and norepinephrine. There was no elevation of concentrations of nitrite and nitrate. Pretreatment with TCV-309, a specific potent PAF antagonist, reduced LPS-induced hypotension and attenuated LV functional and structural changes. TCV-309 administration reduced the LPS-induced adrenergic activation and hemoconcentration. CONCLUSIONS: The hypotension that occurred during the initial phase of LPS-induced shock was accompanied by LV functional and structural alterations. The marked increase in LV wall thickness can be ascribed to the congestion of capillaries and edema in the LV myocardium. Pretreatment with a PAF antagonist reduced LPS-induced alterations. PAF may play a pivotal role during the initial phase of LPS-induced cardiovascular responses.

Activation of soluble polysaccharides with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) for use in protein-polysaccharide conjugate vaccines and immunological reagents. II. Selective crosslinking of proteins to CDAP-activated polysaccharides.

Covalently linking protein to polysaccharides converts the anti-polysaccharide immune response from a T-cell independent response to one which is T-cell dependent. The organic cyanylating reagent 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) (Vaccine 14:190, 1996) has been used to activate polysaccharides, which can then be reacted with spacer reagents or directly with protein. We wished to explore ways in which proteins could be linked to CDAP-activated polysaccharides to conjugate in a more controlled and selective fashion. To this end, we examined the reaction of nucleophilic amino acids with CDAP-activated polysaccharides under basic and acidic conditions. We found that lysine, cysteine and histidine but not methionine, serine or tyrosine conjugated to CDAP-activated dextran. We also examined the reaction of various spacer reagents with CDAP-activated dextran as a function of pH. The addition of hexanediamine was highly pH dependent and maximal at pH 9.3. In contrast, the addition of adipic dihydrazide, which has a pKa of ca 2.5 was essentially independent of pH. By performing the conjugation reaction at pH 5, we were able to selectively couple hydrazides even in the presence of high concentrations of amines. Proteins derivatized with limited numbers of hydrazides could be conjugated to CDAP-activated polysaccharides at pH5, where the native protein was not reactive. Proteins could be derivatized with hydrazides on carboxyls using adipic dihydrazide and a water soluble carbodiimide or on amines using a mild two-step reaction. Tetanus toxoid-pneumococcal type 14 conjugates produced by coupling hydrazide-derivatized tetanus toxoid under acidic conditions induced anti-polysaccharide antibodies at titers comparable to that stimulated by conjugates produced using a basic coupling pH. Our data suggest that crosslinking was occurring only with the limited number of hydrazides on the protein and that we achieved limited and selective crosslinking between the protein and CDAP-activated polysaccharide. This work also demonstrates that CDAP-mediated conjugation to polysaccharides can be applied even to very pH sensitive proteins and polysaccharides.

Activation of soluble polysaccharides with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate for use in protein-polysaccharide conjugate vaccines and immunological reagents.

Neonates have poor immune responses to type 2 T-cell independent antigens (TI-2), such as polysaccharides and immunization of human infants with these antigens does not induce protective levels of serum antibodies. Conjugating proteins to TI-2 antigens converts the immune response to one which is T-cell dependent. We used an organic cyanylating reagent, 1-cyano-4-dimethylaminopyridinium tetrafluroborate (CDAP), to activate polysaccharides, in water, and subsequently react them with hexanediamine, in preparation for coupling proteins to the polysaccharide. CDAP activation of polysaccharide is rapid (< 2 min) and efficient. CDAP can be used to activate polysaccharides of diverse chemical natures, including dextrans and pneumococcal types 6, 14, 19 and 23. The critical parameters in CDAP activation of polysaccharides were the reagent concentrations and the pH. Activation can be performed over a broad alkaline pH range, with an optimum of pH 9-10. Furthermore, proteins can be coupled to CDAP-activated polysaccharides without the use of a spacer. Direct conjugation of protein to CDAP-activated polysaccharides can be performed under mildly alkaline conditions (pH 7-9). These conditions allow CDAP to be used with alkaline-sensitive polysaccharides and proteins. Mice immunized with BSA-pneumococcal type 14 polysaccharides (Pn14) conjugates, prepared either by direct conjugation or via a spacer, had high anti-Pn14 and anti-BSA serum antibody IgG1 titers, whereas no IgG1 antibody was induced to the unconjugated components. The ease of use and mild activating conditions should prove of value in using CDAP to prepare conjugate vaccines, as well as other immunologically useful reagents.

Cross-reactivity of metocurine, atracurium, vecuronium and fazadinium with IgE antibodies from patients unexposed to these drugs but allergic to other myoneural blocking drugs.

An inhibition assay was used to determine quantitatively the allergenic cross-reactivity of some myoneural blocking drugs not yet released for use in Australia, in the sera of patients who had experienced anaphylactic reactions to neuromuscular blocking drugs. Two of the compounds, metocurine and atracurium were highly cross-reactive with the currently used myoneural blockers; fazadinium was weakly cross-reactive and vecuronium intermediate in potency between these two extremes. From these results, we predict that anaphylactic reactions to these compounds, and particularly to metocurine and atracurium, will occur in some patients allergic to the currently used neuromuscular blocking agents.

[Modification of the immune response by using an antigen bound to synthetic polyelectrolytes]. / Modifikatsiia immunnogo otveta pri pomoshchi antigena, sviazannogo s neprirodnymi poliélektrolitami.

The immunogenic properties of the soluble complexes of bovine serum albumin (BSA) and synthetic polyelectrolytes were studied. The polyelectrolytes used in these complexes were 4-vinyl-N-ethylpyridinium bromide and 4-vinyl-N-cetylpyridinium bromide (complex I), 4-vinylpyridine and 4-vinyl-N-acetylpyridinium bromide (complex II). C57BL mice were immunized with different doses of BSA, complexes I and II introduced intraperitoneally in a single injection, and the number of plaque-forming cells (PFC) in the spleen was determined by modified Jerne's test with the use of BSA-covered sheep red blood cells. The above complexes were shown to stimulate the production of PFC against BSA 50-100 times more intensively than pure BSA. The mixtures of BSA with the above-mentioned polyelectrolytes stimulated PFC production to a considerably lesser extent. Thus, the polymeric part of these conjugates was not an antigen, but served as a carrier inducing pronounced immune response to the antigenic (protein) part of the complex.¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿¿