The immunogenicity of p24 protein from HIV-1 virus is strongly supported and modulated by coupling with liposomes and mannan

Anti-viral and anti-tumor vaccines aim to induce cytotoxic CD8+ T cells (CTL) and antibodies. Conserved protein antigens, such as p24 from human immunodeficiency virus, represent promising component for elicitation CTLs, nevertheless with suboptimal immunogenicity, if formulated as recombinant protein. To enhance immunogenicity and CTL response, recombinant proteins may be targeted to dendritic cells (DC) for cross presentation on MHCI, where mannose receptor and/or other lectin receptors could play an important role. Here, we constructed liposomal carrier-based vaccine composed of recombinant p24 antigen bound by metallochelating linkage onto surface of nanoliposomes with surface mannans coupled by aminooxy ligation. Generated mannosylated proteonanoliposomes were analyzed by dynamic light scattering, isothermal titration, and electron microscopy. Using murine DC line MutuDC and murine bone marrow derived DC (BMDC) we evaluated their immunogenicity and immunomodulatory activity. We show that p24 mannosylated proteonanoliposomes activate DC for enhanced MHCI, MHCII and CD40, CD80, and CD86 surface expression both on MutuDC and BMDC. p24 mannosylated liposomes were internalized by MutuDC with p24 intracellular localization within 1 to 3 h. The combination of metallochelating and aminooxy ligation could be used simultaneously to generate nanoliposomal adjuvanted recombinant protein-based vaccines versatile for combination of recombinant antigens relevant for antibody and CTL elicitation.

Imaging of transfection and intracellular release of intact, non-labeled DNA using fluorescent nanodiamonds

Efficient delivery of stabilized nucleic acids (NAs) into cells and release of the NA payload are crucial points in the transfection process. Here we report on the fabrication of a nanoscopic cellular delivery carrier that is additionally combined with a label-free intracellular sensor device, based on biocompatible fluorescent nanodiamond particles. The sensing function is engineered into nanodiamonds by using nitrogen-vacancy color centers, providing stable non-blinking luminescence. The device is used for monitoring NA transfection and the payload release in cells. The unpacking of NAs from a poly(ethyleneimine)-terminated nanodiamond surface is monitored using the color shift of nitrogen-vacancy centers in the diamond, which serve as a nanoscopic electric charge sensor. The proposed device innovates the strategies for NA imaging and delivery, by providing detection of the intracellular release of non-labeled NAs without affecting cellular processing of the NAs. Our system highlights the potential of nanodiamonds to act not merely as labels but also as non-toxic and non-photobleachable fluorescent biosensors reporting complex molecular events.

Charge-sensitive fluorescent nanosensors created from nanodiamonds

We show that fluorescent nanodiamonds (FNDs) are among the few types of nanosensors that enable direct optical reading of noncovalent molecular events. The unique sensing mechanism is based on switching between the negatively charged and neutral states of NV centers which is induced by the interaction of the FND surface with charged molecules.

Stimulation of innate immunity in newborn kids againstCryptosporidium parvuminfection-challenge by intranasal/per-oral administration of liposomal formulation of N-L18-norAbu-GMDP adjuvant

The effects of a liposomal preparation of lipophilic immunomodulator β-D-GlcNstearoyl-(1-4)-norMurNAc-L-Abu-D-isoGln (N-L18-norAbu-GMDP) were investigated on resistance toCryptosporidium parvuminfection in neonatal kids. The liposomal preparation was administered subcutaneously or intranasally/orally (i.n./p.o.) twice at doses of 100 μg, 200 μg, or 1000 μg per kid pre-infection challenge. The treatment schemes were (i) 72 and 24 h pre-infection challenge, (ii) 24 h pre-infection challenge and 24 h post-infection challenge (oral inoculation with 1×107oocysts ofC. parvumin 5 ml of PBS). Administration of liposomal N-L18-norAbu-GMDP by i.n./p.o. route at the cumulative dose of 2000 μg per kid 72 and 24 h pre-infection challenge, lead to substantially increased clearance of coccidian parasites from various parts of the intestine. On the basis of histological examination, the distribution of cryptosporidia in the intestine and the severity of the infection, treated kids were classified on day 5 as having a strong reduction in infection in comparison to the control group (P<0·05). No cryptosporidia were found on the mucosal surface of treated kids by day 10, while the intestines of the control kids were still infected. All doses and routes of administration were judged effective with respect to suppression of cryptosporidia infections.

The thin electrolyte layer approach to corrosion testing of dental materials--characterization of the technique

An innovative technique for corrosion testing of metallic dental materials is introduced. The thin electrolyte layer technique (TET) simulates the physical characteristics of the oral environment by employing a still, thin layer of an electrolyte, in contrast to bulk electrolyte techniques (BET) which utilize relatively large quantities of fluid. Limiting current density tests on a platinum electrode revealed a lower surface oxygen content for TET. Borate buffer (pH 6.8) was employed as an electrolyte. The effect of lower oxygen content in TET on passivation and polarization characteristics of 316L SS in 0.9% saline was investigated. The results revealed differences in the polarization resistance and open circuit potential development with time, as well as in anodic and cathodic polarization behavior. Lower O2 concentration in TET was attributed to different electrolyte convection characteristics under both testing conditions. Additionally, use of the TET resulted in better data reproducibility. Overall, this investigation led to a deeper understanding of the electrochemical processes inherent in thin electrolytes such as those found in the oral environment.

Stimulation of haemopoiesis and protection of mice against radiation injury by synthetic analogues of muramyldipeptide incorporated in liposomes

Protection from undesirable effects of radiotherapy or chemotherapy, primarily from myelosuppression, remains still a crucial problem to be studied. Attention has been therefore paid to various immunomodulatory agents that through the monocyte/macrophage system induced production of cytokines, which can induce and operate restoration of haemopoiesis and thus act radioprotectively. Some synthetic analogues of MDP free of undesirable side-effects, were synthesized in the Czech Republic. Lipophilic beta-D-GlcNstearoyl-(1- > 4)-norMurNAc-L-Abu-D-isoGln (DDD-St) was designed to be easily entrapped into liposomes and this liposomal DDD-St protected efficiently mice against irradiation, when administered i.p., i.v. or s.c. 24 h prior to lethal irradiation (survival rate in the range of 30-80% compared with 0% in control). Especially the subcutaneous application of liposomal DDD-St was very efficient. The parameters characteristic of recovery of haemopoiesis in bone marrow on day 10 after 6.5 Gy irradiation were significantly improved in comparison with the controls. Very high radioprotective effect of s.c. administered liposomal DDD-St can be explained (together with induction of haemopoiesis) by an effective and long-lasting activation of nonspecific immunity, which is able to withhold an onset of septicemia in early days after irradiation. In conclusion, the liposomal DDD-St should be therapeutically beneficial in moderating the haemopoietic damage, which is an undesirable effect of radiotherapy or chemotherapy.

Synthesis of O-[2-acetamido-2-deoxy-6-O-stearoyl- and -6-O-(2-tetradecylhexadecanoyl)-beta-D-glucopyranosyl]-(1-->4)-N- acetylnormuramoyl-L-alpha-aminobutanoyl-D-isoglutamine, lipophilic disaccharide analogues of MDP

Silver triflate-promoted condensation of 3,4,6-tri-O-acetyl-2-deoxy-2- phthalimido-beta-D-glucopyranosyl bromide (1) with benzyl 2-acetamido-6-O-benzyl-2-deoxy-3-O- (methoxycarbonyl)methyl-alpha-D-glucopyranoside (4) afforded the key compound, benzyl 2-acetamido-6-O-benzyl-2-deoxy-3-O- (methoxy-carbonyl)methyl-4-O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b eta-D- glucopyranosyl)-alpha-D-glucopyranoside (5), which after deprotection was transformed into acid 10. Condensation of 10 with the benzyl ester of L-alpha-aminobutanoyl-D-isoglutamine and deisopropylidenation of the product 11 afforded the benzyl ester of N-(2-O-[benzyl 2-acetamido-4-O-(2-acetamido-3-O-benzyloxymethyl-2- deoxy-beta-D-glucopyranosyl)-6-O-benzyl-2,3-dideoxy-alpha-D-glucopyra nosid-3- yl]glycoloyl)-L-alpha-aminobutanoyl-D-isoglutamine (12). Partial O-acylation of 12 and hydrogenolysis of protecting groups gave the 6-O-stearoyl- and 6-O-(2-tetradecylhexadecanoyl)-disaccharide-dipeptides 17 and 18, respectively. Pyrogenicity and adjuvant activity in cell-mediated immunity are reported.

Formation of collagen-like fibrils from alpha-elastin

Collagen-like structures were formed in solutions of alpha-elastin after heating to 57 degrees C and after treatment with absolute ethanol. A complex between acetyl-alpha-elastin and cetyltrimethylammonium bromide showed a similar structure. Thick fibrils (diameter approximately 100 nm), resembling those described by Volpin, et al.12 revealed transversal banding with periodicity of 39 to 62 nm. A possible mechanism for the formation of these fibers is suggested based on hydrophobic interactions.

Fibrillar structure of alpha-elastin methylester complexes with glycoproteins and proteoglycans

alpha-Elastin methylester forms with proteoglycan subunits and structural glycoproteins water-insoluble complexes which after staining with phosphotungstic acid (pH 7.0), reveal at large magnification bundles of slender smooth fibrils with a diameter from 4 to 5 nm. Similar fibrils can be observed after interaction of alpha-elastin methylester with chondroitin sulfate, but only if fixation with glutaraldehyde is used prior to staining. Phosphotungstic acid alters the organization of the complexes, in particular those formed with ligands of low molecular weight. The possible biological significance of the interactions studied is discussed.

Superoxide dismutase levels in various radioresistant and radiosensitive tissues of irradiated rats

The activity of superoxide dismutase (E.C. 1.15.1.1; SOD) was determined in male Wistar rats in order to evaluate the possible relationship between both the enzyme content in tissue and the resistance of this tissue to ionizing radiation (8,0 Gy, 60Co). Our results showed that some non-irradiated radioresistant organs (liver) had a high SOD activity and on the contrary, in some radiosensitive tissue (bone marrow) the SOD content was low. In spite of this observation it is not possible to generalize the statement that the radiosensitivity is directly conditioned by the SOD level without any exception. The SOD content in the spleen was higher than in the brain, but the spleen is remarkably radiosensitive, whereas the brain is not. The radiosensitivity of individual tissues probably reflected the changes of SOD activity after the irradiation.

Interaction of a tropoelastin model with connective tissue components

It has been suggested that tropoelastin interacts with macromolecular components of connective tissue during the formation of elastic fibers. alpha-Elastin, used traditionally as a model of tropoelastin and mature elastin, is not suitable for the monitoring of this interaction in vitro. Therefore a new model of tropoelastin, the methyl ester of alpha-elastin, was synthesized and the interaction of this modified elastin with hyaluronic acid, chondroitin sulfate, proteoglycan subunits, solubilized structural glycoproteins and collagen was studied by turbidimetric measurement. Results indicate that alpha-elastin methyl ester is a better model of tropoelastin than alpha-elastin especially in those experiments where ionic interactions are believed to occur. It was also found that alpha-elastin methyl ester formed aggregates with hyaluronic acid, chondroitin sulfate, proteoglycan subunits and solubilized structural glycoproteins at room temperature and under conditions close to physiological ones. Alpha-elastin does not interact with these compounds under similar conditions. The character of the bonds involved in the interaction and the possible biological significance of the experiments are discussed.

Influence of radioprotective agents on the activities of isoenzymes of blood serum alkaline phosphatase in irradiated dogs

Changes of the total serum activity of alkaline phosphatase (AP) and its bone and intestinal isoenzymes were studied in dogs gamma-irradiated by 3.0 Gy. The activities of AP isoenzymes were determined by means of a heat inactivation-inhibition method. After irradiation the serum AP activities were lower in general. In case of the bone isoenzyme the decrease was most pronounced. The changes of the total AP activity and of the intestinal isoenzyme were less distinct. The i.m. administration of the radioprotective mixture cystamine with mexamine (24 mg/kg + 4 mg/kg) before irradiation led only to a moderate reduction of the radiation-altered AP values in the dogs. The present results indicate that the radioprotective way used here renders only an unsatisfactory protection for large laboratory animals against ionizing radiation.

The concentrations of SH-groups in some radiosensitive tissues after the administration of radioprotectors in rats

The changes in the concentrations of total, nonprotein and protein SH-groups were spectrophotometrically determined in the small intestine and bone marrow of the rats 10, 20, 30 and 60 min after the administration of protective doses of cystamine (50 mg/kg), mexamine (10 mg/kg) or of a mixture of cystamine with mexamine (20 + 10 mg/kg). Cystamine caused an increase in the concentration of mainly nonprotein thiols, whereas the mexamine administration increased the protein SH-groups (mainly between the 20th and 30th min after treatment). The radioprotective mixture led to the most pronounced increase at the 10-min interval. This increase at the 10- and 20-min intervals was more pronounced (or identical) than after cystamine or mexamine administered as a single agent. If the SH-concentration should correspond to the degree of radioprotection, then the phenomenon observed would indicate the usefulness of the mixture administered.

Interaction of alpha-elastin with ionic detergents

Coacervation is known to be a fundamental step in elastogenesis that is influenced by various naturally occurring substances in connective tissue. Therefore, interaction of alpha-elastin with ionic detergents (sodium dodecyl sulfate, dodecylbenzyldimethylammonium bromide, cetyltrimethylammonium bromide, pentadecacarbethoxytrimethylammonium bromide and cetylpyridinium bromide) was studied as a model for the elastin interaction with amphipilic substances. The course of the interactions was followed by the effect on thermal coacervation, solubilization of lipophilic dye, difference spectra measurements and fluorescence probe. The results indicate that the detergents examined interact with alpha-elastin below critical micelle concentration in two different ways. In the first case, a mixed micelle can be formed from the detergent molecules (SDS, DBD) and alpha-elastin: alternatively mixed micelles are not formed, but the detergent molecules (CT, PCT, CP) do interact with elastin. The interaction of alpha-elastin at the isoelectric point was found to depend more on the chemical structure of the detergent molecule than on its charge. If detergent concentrations above the critical micelle concentration were applied, the interaction mechanism was different from that observed at lower detergent concentration.

The content of dityrosine in chick and rabbit aorta proteins

The possible presence of dityrosine in elastin derived by two different methods and in structural glycoproteins from aortas of 1 day old chicks, adult rabbits and fetal rabbits was determined by a sensitive spectrofluorimetric procedure. Only chick tissues were found to contain dityrosine, 0.3 residues/100,000 total amino acid residues in aortic elastin and 12-15 residues/100,000 residues in the structural glycoproteins. No dityrosine could be detected in any of the fetal or mature rabbit tissues. However, related fluorescent compounds with different excitation-emission maxima and different elution times were obtained by ion exchange chromatography of structural glycoproteins partially hydrolyzed under alkaline conditions.

Preparation and isolation of dityrosine

A new procedure for the isolation of dityrosine has been developed. Tyrosine was oxidized by means of incubation both with hydrogen peroxide and horse-radish peroxidase. The reaction mixture was separated by permeation chromatography on Sephadex G-10 being monitored at 280 and 310 nm spectrophotometrically. The dityrosine fraction was freeze-dried and purified on a cation-exchange column (in acidic citrate buffer). The purified fraction was desalted and freeze-dried. The yield was 96 mg of homogenous dityrosine per 1 g of D,L-tyrosine. Some physico-chemical constants of the preparation were measured (optical characteristics with U.V. and I.R. spectra, fluorescence spectra, chromatography on an amino acid analyzer).

The changes in pharmacokinetics and conjugation of chloramphenicol in irradiated rats

In the serum and the liver of rats levels of chloramphenicol (CAP) following its i.v. administration (200 mg/kg) in the control groups and in the rats irradiated with whole-body air exposure to 500 R were determined with spectrophotometric methods. The CAP-levels in the serum increased in the group of rats 3 days after irradiation, but only during the 1st hour. At later time intervals the values were lower than in the controls. This decrease at the 60th min is striking even in the groups 6 and 9 days after exposure. Free CAP in the liver of rats irradiated 6 and 9 days before was lower at interval 30 min after CAP-administration, but the group irradiated 9 days before was unaltered. However, 120 min after CAP-administration the values of free CAP decreased at all intervals investigated following the irradiation. The levels of conjugated CAP in the liver of the rats 3 and 6 days after exposure were lower than in controls in both intervals after drug administration; but in rats 9 days after irradiation they increased. Our results indicate that the kinetics of CAP is altered and corresponding changes in its conjugation are effected under the condition of acute radiation syndrome.

A comparative study of two isolation procedures for elastin and contaminating substances in fetal and adult rabbit aortas

A quantitative study of the individual steps in the isolation of elastin from mature and fetal aortas of rabbits was carried out. The proportions of insoluble residue and acetone- and ether-soluble substances were determined. The yields of elastin and other associated components of connective tissue derived from the aortas by two different isolation procedures were compared, i.e. the classical Lansing treatment with hot alkali and the less drastic procedure described by Rasmussen et al. Results were found to be strongly influenced by the method used. The purity of the elastin preparations was evaluated by means of amino acid analyses for relative contents of desmosines and dicarboxylic amino acids. The possible reasons for the differences found are discussed.

Fluorescent substances in protein hydrolysates. II. Comparison of some protein and peptide hydrolysates

Fluorescence was measured in the hydrolysates of several proteins and peptides of known amino acid composition. The most intense fluorescence (emission maximum at 445 nm) was found in acid, but not enzymic, hydrolysates of tryptophan-rich proteins; nine fluorescent fractions were resolved from acid hydrolysates of these proteins by gel filtration. Fluorescence of substances in tryptophan-containing proteins is largely eliminated by reduction, but little affected by oxidation or ultraviolet irradiation. The substances are thermostable and apparently are not amino acids.Tyrosine, tyrosine-containing peptides, and tryptophan-free proteins yielded fewer fluorescent products than did tryptophan-rich proteins. The number and amount of fluorescent derivatives produced from tyrosine during acid hydrolysis depends on the particular protein; also, intra- or intermolecular interactions involving tyrosine or its degradation products appear to influence the nature of fluorescence in protein hydrolysates.The present findings suggest possible quantitation of the tryptophan content of proteins by fluorometric measurement of tryptophan derivatives produced by acid hydrolysis.

Characteristics of beta-galactosidase in the mucosa of the small intestine of infant rats. Physicochemical properties

1. The characteristics of acid and neutral beta-galactosidases isolated chromatographically from homogenates of the mucosa of the jejunum and ileum of suckling rats were studied. 2. The minimal molecular weight of the acid beta-galactosidase, as estimated by gel filtration on Sephadex G-200, was in the range 83000-105000, whereas for the neutral beta-galactosidase the estimated molecular weight was in the range 360000-510000. 3. The acid and neutral beta-galactosidases were inhibited competitively by galactono-(1-->4)-lactone, with respective K(i) values of 0.15mm and 1.1mm. Only the acid beta-galactosidase was inhibited competitively by sodium galactonate (K(i) 0.17mm). 4. Heat inactivation of both beta-galactosidases occurred according to first-order kinetics. The neutral enzyme was more labile, but bovine serum albumin protected acid enzyme only. 5. Urea treatment inactivated both beta-galactosidases, the neutral beta-galactosidase being more sensitive than the acid beta-galactosidase. 6. No differences were found between preparations from the jejunum and ileum.