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PubMed1974

Genetic control of the antibody response to poly-L(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys in C3H--CWB tetraparental mice.

In order to further delineate the mechanisms underlying genetic unresponsiveness, tetraparental mice were constructed from immune response-1A gene high responder and low responder parental genotypes, then were immunized with poly-L-(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys ((T,G)-A--L). An analysis of the total serum allotype mixture and of the antigen-binding capacity of the separated allotypes demonstrated that in the milieu of a tetraparental mouse, both high and low responder B cells could be stimulated equally to produce identical high titered anti-(T,G)-A--L responses. Furthermore, these studies show that effective stimulation could occur across a histocompatibility disparity.

Animals↗

PubMed1976

Antibody response of C3H in equilibrium (CKB X CWB)F1 tetraparental mice to poly-L(Tyr,Glu)-poly-D,L-Ala-poly-L-Lys immunization.

To test whether the antigen-specific stimulation of low responder-genotype B cells in tetraparental mice is due to a histoincompatibility reaction (allogeneic effect) against these B cells, tetraparental mice were constructed (a) between an Ir-1A low responder to the antigen poly-L(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys. [(T,G)-A--L] and an Ir-1A F1 high responder and (b) between two histoincompatible Ir-lA low responders. In the first case the F1 high responder embryo shares the whole of the H-2 complex, including Ir, with the low responder embryo.

Animals↗

PubMed1978

The role of H-2-linked genes in helper T-cell function. III. Expression of immune response genes for trinitrophenyl conjugates of poly-L(Tyr, Glu)-poly-D,L-Ala--poly-L-Lys in B cells and macrophages.

Using lymph node T cells from poly-L(Tyr,Glu)-poly-D,L-Ala--poly-L-Lys[(TG)-A--L]-primed animals and B cells from animals primed with trinitrophenylated (TNP) protein or lipopolysaccharide, we have obtained anti-TNP-(TG)-A--L direct plaque-forming responses in vitro. Response to this antigen was shown to be controlled by the H-2 haplotype of the animal studied. The strain distribution of in vitro response was very similar to that previously reported by others for in vivo secondary IgG responses to (TG)-A--L. We investigated the cell types expressing the Ir gene(s) for (TG)-A--L in our cultures. F1, high responder x low responder mice were primed with (TG)-A--L. Their T cells were active in stimulating anti-TNP-(TG)-A--L responses of high responder but not low responder B cells and macrophages (MPHI), even though both preparations of B cells and Mphi were obtained from mice congenic at H-2 with one of the parents of the F1. For three low responder strains tested, of the H-2h2, H-2k, and H-2f haplotypes, the anti-TNP-(TG)-A--L response of low responder B cells and Mphis in the presence of high responder, F1 T cells could not be improved by the addition of high responder, antigen-bearing Mphis to the cultures. In one strain of the H-2a haplotype, it was shown that neither the B cells nor Mphis could be functional in anti-TNP-(TG)-A--L responses. Our results therefore suggested the Ir genes for anti-TNP-(TG)-A--L responses were expressed at least in B cells in all the low responder strains we studied, and, in mice of the H-2a haplotype, in Mphis too.

Animals↗

PubMed1980

Genetic regulation of delayed-type hypersensitivity responses to poly(LTyr,LGu)-poly(DLAla)--poly(LLys). I. Expression of the genetic defect at two phases of the immune process.

Delayed-type hypersensitivity (DTH) responses served in this study as an experimental model for the analysis of genetic regulations of T-cell responses. Educated irradiated cells from H-2b mice mediated responses in syngeneic recipients, whereas mice of the a, d, f, k, and s haplotypes were nonresponders to poly(LTyr,LGlu)-poly(DLAla)--poly(LLys)[(T,G)-A--L]. These results suggest that cell-mediated immune responsiveness to (T,G)-A--L is linked to the H-2 complex, as was shown for humoral responses. Educated irradiated T cells of F1 hybrids between high and low responders mediated DTH responses, which indicates that the gene(s) controlling the DTH responses is dominant. To analyze the genetic defect in DTH responses to (T,G)-A--L, we separated the T-cell activation phase from the effector phase that was determined in recipient mice. Two types of nonresponders were observed: (a) When lymphocytes of the a or k haplotypes were educated in a syngeneic environment and then transferred into hybrids between the parental (nonresponder x responder) F1 recipients, DTH responses could have been manifested. (b) On the other hand, no DTH responses could be mediated by transferring educated cells of the H-2s or H-2f origin into the appropriate F1 recipients. In addition, irradiated F1 cells that had been activated to (T,G)-A--L could not mediate DTH responses in both types of nonresponder recipients. These results suggest that T cells of H-2k or H-2a mice can be activated to generate DTH responses to (T,G)-A--L and that the defect in these mouse strains is expressed in another cell population needed for the manifestation of the DTH reaction in the recipient mice. In contrast, T cells of H-2s and H-2f origin cannot be activated to (T,G)-A--L and, thus, fail to manifest DTH responses.

Animals↗

PubMed1980

Genetic regulation of delayed-type hypersensitivity responses to poly(LTyr,LGlu)-poly(DLAla)--poly(LLys). II. Evidence for a T-T-cell collaboration in delayed-type hypersensitivity responses and for a T-cell defect at the efferent phase in nonresponder H-2k mice.

The intercellular interactions and the site of the genetic defect in delayed-type hypersensitivity (DTH) response to poly(LTyr,LGlu)-poly(DLAla)--poly(LLys) [(T,G)-A--L] has been studied in a system where the T-cell education phase was separated from the efferent phase. In the cellular response, T-T-cell collaboration is required, because T cell-depleted mice were unable to manifest DTH responses after they were transferred with educated and irradiated T cells. Reconstitution of adult thymectomized mice that were irradiated and supplemented with bone marrow cells after treatment with anti-Thy-1.2 serum and complement, with T cells but not with accessory cells gave rise to significant responses. Educated, radioresistant cells required the presence of normal radiosensitive T cells for successful DTH responses to (T,G)-A--L. The genetic defect of nonresponder H-2k and H-2a mice has been located in the above-mentioned, second T-cell population that participates in the efferent phase of this immune reaction. Further characterization revealed that the educated cells are of the Lyt1+ phenotype and that the second normal T cells are expressing the Lyt 1+,2+,3+ phenotype. Thus, the genetic defect of H-2k and H-2a mice in the DTH response to (T,G)-A--L is expressed on the non-antigen-stimulated Lyt 1+,2+,3+ T cells.

Animals↗

PubMed1978

Identification of different antigenic determinants within the synthetic multichain Co-polymer poly(LTyr,LGlu)-poly(DLAla) -- poly (LLys), (T,G)-A--L, as recognized by the chicken. II. Fine-specificities of the anti-(T,G) part of chicken anti-(T,G)-A--L antisera.

Sera from three chickens obtained from a genetic high-responder inbred strain immunized with the multichain polypeptide poly(LTyr,LGlu)-poly-(DLAla)--poly(LLys) (T,G)-A--L) were analysed for possible restrictions in the fine-specificities of anti-(LTyr,LGlu) antibodies. A panel of synthetic hexa- and heptapeptides composed of L-Tyr and L-Glu residues linked to a C-terminal spacer tripeptide, and with L-Tyr as N-terminal, were used as inhibitors in a double-antibody radioimmunoassay. Results showed that all peptides tested possessed some inhibitional potential, although the percentage of displacement for the different sequences varied between 43% and 58%,20% and 56%, and 48% and 85%, respectively, for the three sera tested at a given inhibitor concentration. Different peptide sequences appeared as the most efficient inhibitor in the three sera tested. No simple relationship was found between substitution/elongation of inhibitor peptides and their inhibitional potential, as would have been expected from a simple conception of (T,G)-A--L possessing only one sequential determinant. Possible evidence for conformational determinants in the (T,G)-A--L antigen is discussed.

Amino Acid Sequence↗

PubMed1998

Adsorption of albumin, collagen, and fibronectin on the surface of poly(hydroxybutyrate-hydroxyvalerate) (PHB/HV) and of poly (epsilon-caprolactone) (PCL) films modified by an alkaline hydrolysis and of poly(ethylene terephtalate) (PET) track-etched membranes.

The effect of alkaline hydrolysis on several surface properties of poly(hydroxybutyrate-hydroxyvalerate) (92/8) (PHB/HV) and poly(epsilon-caprolactone) (PCL) films and of poly(ethylene terephtalate) (PET) track-etched membranes have been characterized, as well as the adsorption of three proteins normally encountered by mammalian cells in vivo, namely albumin, collagen, and fibronectin. The water contact angle decreases and the number of -COOH functions accessible to a chemical reaction at the surface of PCL increases with alkaline hydrolysis. Analysis by atomic force microscopy pictures reveals a change in surface morphology. The modifications of surface properties are correlated with a two times increase of the adsorption of three radiolabelled proteins. The hydrolysis results in a slight increase in the water contact angle of one face of the PHB/HV film and a sharp increase in the number of -COOH functions. Important morphology changes are also induced. The adsorption of the radiolabelled proteins is almost 100 times higher on the hydrolyzed polymer than on the native surface. The increase in hydrophilicity of different PET batches correlates to an increase in the number of -COOH functions. Nevertheless, the surface chemical composition and rugosity are constant and no significant difference in the amount of radiolabelled fibronectin adsorbed on the different surfaces is detectable. In conclusion, the effect of hydrolysis on the surface properties of each of the polyesters studied as well as the proteins adsorption on the different surfaces are different. The results strongly support the hypothesis that, in the system studied, parameters other than hydrophilicity influence protein adsorption: the main parameters that might play a role are the total surface area accessible to the proteins, as well as the surface chemical composition.

Adsorption↗

PubMed1977

Oligopeptides as models for Tyr/Glu sequences in the multichain co-polymer poly(Lys) poly(Tyr, Glu)-poly(DL-Ala).

The syntheses of a number of oligopeptides by classical means are reported. The peptides are designed as models for possible antigenic sequences among the Tyr/Glu sequences of a macromolecule widely used as antigen in immunogenetic studies, the multichain co-polymer, poly(Lys) poly(Tyr, Glu)-poly(DL Ala). Preliminary studies on the biological activity of the oligopeptides synthesized show that only peptides with the N-terminal sequence H-Tyr-Glu- do compete with the co-polymer in a double antibody radioimmune assay, whereas other sequences do not.

Amino Acid Sequence↗

PubMed2002

[Analysis of confined crystalline behaviors of poly(styrene)-poly(ethyleneoxide)-poly(styrene) triblock copolymers by inverse gas chromatography].

The confined crystalline behaviors of the triblock copolymers, poly(styrene)-poly(ethyleneoxide)-poly(styrene) (PS-PEO-PS), were studied by using inverse gas chromatography(IGC) probe technique, including phase-transformation of melting crystalline, crystallinity (Xc), melting temperature(Tm) and melting range of temperature. The effects of the molecule-chain length of linear alkane probes on the results are discussed. Results showed that micro-phase separation of PS-PEO-PS had a greater influence on crystallization of PEO molecule-chain. Crystalline-structure of PS-PEO-PS had interphase formed by some kinds of imperfect PEO crystal and amorphous PS. The molecule-chain length of linear alkane probes had no effect on the determination of melting temperature and melting range of temperature of PS-PEO-PS, but had a greater influence on the determination of crystallinity of PS-PEO-PS and investigation phase-transformation of melting crystalline. Crystallinity of PS-PEO-PS determined by IGC was decreased with the increase of molecule-chain length of linear alkane probes. By suitable shorter molecule-chain length of linear alkane probes, it was truer to reflect the existence of interphase of PS-PEO-PS and multi-phase-transformation of melting crystalline presenting in interphase.

English Abstract↗

PubMed1983

[Effects of poly-L-lysine, poly-L-glycine and poly-L-glutamic acid on ANS fluorescence and electrokinetic potential of splenic lymphocytes in the mouse].

The in vivo effect of either poly-L-Lysine, poly-L-Glutamic acid or poly-L-Glycine on mouse spleen cell populations was investigated. The membrane fluorescence changes of activated splenic lymphocytes were studied. Experiments were performed with the hydrophobic fluorescent probe: 1-anilino-8-naphthalene sulphonate (ANS). Kinetic studies further indicated that the course of fluorescence changes may vary considerably depending upon homopolymers. These fluorescence intensity changes would be in direct or inverse relation to the electrokinetic surface potential changes of activated lymphocytes, as assessed by the electrophoretic mobility analysis. It could be concluded that the relation (direct or inverse) between ANS fluorescence and electrokinetic potential depends upon the net electrical charge of the homopolymer used. In further experiments, the determination of the net electrical charge of some tumour antigens could be considered without hard purifications.

Action Potentials↗

PubMed1980

The T lymphocyte proliferative response to poly-L-Glu-poly-D,L-Ala--poly-L-Lys.

The immune response to several antigens has been shown to be under the control of two complementing major histocompatibility-linked immune response (Ir) genes. In most cases, one gene has been mapped to the I-A subregion and the other to the I-E/C subregion. However, in some cases F1 complementation has been described between two alleles in the I-A subregion, so called beta-beta complementation. In these examples, complementation has been seen at the antibody level but not in a T lymphocyte proliferation assay. In the present work, we studied the T cell proliferative response to poly-L-Glu-poly-D,L-Ala--poly-L-Lys (G-A--L). Peritoneal exudate, T lymphocyte-enriched subpopulations (PETLES) from F1 hybrids between C57BL/10 and B10.A, C57BL/10, and B10.A(4R), or B10.A and B10.A(3R) or (5R) mice responded well to G-A--L. In contrast, PETLES from F1 hybrids between C57BL/10 and B10.A(5R) or B10.A and B10.A(4R) mice, as well as from all inbred strains tested, failed to respond to G-A--L. These results demonstrate for the first time an example of Ir gene complementation at the T cell level in which both genes map to the left of the I-J subregion presumably in I-A. This system should now allow us to determine whether alpha-beta and beta-beta complementation take place through the same biologic mechanism.

Animals↗

PubMed1982

Genetic control of the antibody response to poly(L Tyr, L Glu)-poly(DL Ala)--poly(L Lys) in mice: analysis of (low responder x low responder)F1 hybrids.

The antibody response to the synthetic polypeptide poly (L Tyr, L Glu)-poly (DL Ala)--poly (L Lys) designated (T,G)-A--L, was investigated in inbred, congenic, F1 and F2 hybrid strains of mice. The antibody response was analysed at both low (10 microgram) and high (50 microgram) immunizing doses of (T,G)-A--L. Antibodies were measured using both a modified Farr assay and a plate binding assay. At low immunizing doses it was found that all of the congenic and non-congenic (low responder x low responder) F1 hybrids were low responders. However, the quantitative antibody response of one non-congenic (low responder x low responder) F2 hybrid segregated in a 1:1 ratio of high responders to low responders, suggesting some form of complementation of (T,G)-A--L Ir genes. At high immunizing doses it was found that congenic and non-congenic (low responder x low responder) F1 hybrids were all high responders, indicating a complementation of Ir genes to (T,G)-A--L. This complementation was confirmed using two different routes of immunization, namely footpad and intraperitoneal. Furthermore the quantitative antibody responses of (low responder x low responder) F2 hybrids segregate in a 1:1 ratio of high responders to low responders. The class of antibodies produced to (T,G)-A--L in (low responder x low responder) F1 hybrids was determined by gel filtration on Sephadex G-200, and found to be predominantly IgG, with lesser amounts of IgM.

Animals↗

PubMed1982

Genetic regulation of delayed-type hypersensitivity responses to poly (Tyr,Glu)-poly(DLAla)--poly(Lys): expression of the genetic defect in the induction and manifestation phases in H-2s and H-2f mice.

The genetic defect of H-2s and H-2s non-responder mouse strains in both the induction and manifestation phases of delayed-type hypersensitivity (DTH) responses to poly(LTyr,LGlu)-poly(DLAla)--poly(LLys)[(T,G)-A--L] was analysed. Utilizing an in vitro system to activate DTH effector T cells, we observed that non-adherent T cells of (H-2f X H-2b) F1 or (H-2s X H-2b)F1 responder mice, could not be activated on antigen bearing adherent cells of H-2f or H-2s haplotypes. On the other hand, these T cells were effectively sensitized on adherent cells derived from either F1 or parental (H-2b) responder mice. These results indicate that in these mouse strains the genetic defect, in the induction phase of DTH, is expressed at the level of the antigen presenting cell. In subsequent experiments, we were able to "correct' the non-responsiveness of H-2s recipients by transfer of educated and irradiated (H-2s X H-2b)F1 T cells together with normal F1 adherent cells. Normal non-adherent and nylon wool enriched T cells failed to restore these responses. Similarly, antigen-pulsed F1 irradiated peritoneal exudate cells could stimulate DTH responses in SJL recipients of (SJL X C57BL/6)F1 (T,G)-A--L educated cells. The genetic defect of H-2s mice in the manifestation phase of the DTH reaction is thus also expressed on the antigen presenting cell.

Animals↗

PubMed2002

A study of conformational stability of poly(L-alanine), poly(L-valine), and poly(L-alanine)/poly(L-valine) blends in the solid state by (13)C cross-polarization/magic angle spinning NMR.

13C cross-polarization/magic angle spinning (CP/MAS) NMR and (1)H T(1rho) experiments of poly(L-alanine) (PLA), poly(L-valine) (PLV), and PLA/PLV blends have been carried out in order to elucidate the conformational stability of the polypeptides in the solid state. These were prepared by adding a trifluoroacetic acid (TFA) solution of the polymer with a 2.0 wt/wt % of sulfuric acid (H(2)SO(4)) to alkaline water. From these experimental results, it is clarified that the conformations of PLA and PLV in their blends are strongly influenced by intermolecular hydrogen-bonding interactions that cause their miscibility at the molecular level.

Biopolymers↗

PubMed2003

Hydrogels based on poly(ethylene oxide) and poly(tetramethylene oxide) or poly(dimethyl siloxane). III. In vivo biocompatibility and biostability.

To investigate the effects of polymer chemistry and topology (linear or graft copolymer) on in vivo biocompatibility and biostability based on cage implant system, various hydrogels, composed of short hydrophilic [polyethylene oxide (PEO)] and hydrophobic block, were prepared by polycondensation reaction. Poly(tetramethylene oxide) (PTMO) or poly(dimethyl siloxane) (PDMS) was chosen as a hydrophobic block because of their wide utilization as a biomaterial. By using the specimens retrieved from rats killed after 1, 2, 3, 5, and 7 weeks' implantation, cellular and material responses were assessed. Most hydrogels showed a comparable value of macrophage density to Pellethane(R), control polymer, whereas they did significantly lower foreign body giant cell (FBGC) density and coverage because of the presence of PEO. However, PEO block length and polymer topology did not affect macrophage adhesion and FBGC formation in our polymer composition. The hydrogel based on PDMS alone showed significantly lower macrophage density and FBGC density than Pellethane(R), indicating that PDMS plays a role in inhibiting cellular adhesion. The results obtained from gel permeation chromatography curve and Fourier transform infrared spectra exhibited that all the polymers were susceptible to oxidative degradation in vivo. Although Pellethane(R) revealed surface degradation by 5 weeks in vivo, hydrogels showed rapid degradation in the bulk within 2 weeks because of the penetration of oxidative chemicals released from phagocytic cells into PEO domain of phase-separated hydrogels. The more significant degradation was observed in the hydrogels with longer PEO block and PTMO as a hydrophobic block instead of PDMS. It was evident that the minor degradation could be achieved by grafting PEO and adopting PDMS as a hydrophobic block in the hydrogel.

Animals↗

PubMed2006

Synthesis, characterization, and in vitro 5-Fu release behavior of poly(2,2-dimethyltrimethylene carbonate)-poly(ethylene glycol)-poly(2,2-dimethyltrimethylene carbonate) nanoparticles.

Novel ABA-type amphiphilic triblock copolymers composed of poly (ethylene glycol) (PEG) as hydrophilic segment and poly (2,2-dimethyltrimethylene carbonate) (PDTC) as hydrophobic segment were synthesized by ring-opening polymerization of 2,2-dimethyltrimethylene carbonate (DTC) initiated by dihydroxyl PEG. The influence of introducing PEG block on crystalline behavior of PDTC segment was investigated by DSC. Polymeric micelles in aqueous medium were characterized by fluorescence spectroscopy and dynamic light scattering. The critical micelle concentration of these copolymers was in the range of 5.1-50.5 mg/L. Particle size was 80-280 nm. Core-shell-type nanoparticles were prepared by the dialysis technique. Zeta potential was measured by laser Doppler anemometry, and all nanoparticles had negative zeta potential. Transmission electron microscopy images demonstrated that these nanoparticles were spherical in shape. Anticancer drug 5-fluorouracil (5-Fu) as a model drug was loaded in the polymeric nanoparticles. X-ray powder diffraction demonstrated that 5-Fu was encapsulated into polymeric nanoparticles as molecular dispersion. In vitro cytotoxicity of nanoparticles was evaluated by MTT assay. In vitro release behavior of 5-Fu was investigated, and sustained drug release was achieved.

Antineoplastic Agents↗

PubMed2006

Nanoparticles of poly(D,L-lactide)/methoxy poly(ethylene glycol)-poly(D,L-lactide) blends for controlled release of paclitaxel.

Paclitaxel is one of the best antineoplastic drugs found in nature in the past decades, which has excellent therapeutic effects against a wide spectrum of cancers. Because of its high hydrophobicity, Cremophor EL has to be used as adjuvant in its clinical dosage form (Taxol), which has been found to cause serious side effects. Nanoparticles of biodegradable polymers may provide an ideal solution. In this research, paclitaxel-loaded nanoparticles of poly(D,L-lactide)/methoxy poly(ethylene glycol)-polylactide (PLA/MPEG-PLA) blends of various blend ratio 100/0, 75/25, 50/50, 25/75, and 0/100 were formulated by the nanoprecipitation method for controlled release of paclitaxel. It was found that increasing the proportion of MPEG-PLA component in the blend from 0 to 100% resulted in a progressive decrease of the particle size from 230.6+/-11.1 nm to 74.8+/-14.0 nm. The zeta potential of the drug-loaded nanoparticles was increased accordingly from -19.60+/-1.13 mV to a nearly neutral, that is, -0.33+/-0.28 mV, which indicates the gradual enrichment of PEG segments on the particle surface. The findings were further confirmed by X-Ray Photoelectron Spectroscopy (XPS) analysis. Differential scanning calorimetry (DSC) analysis showed that the glass transition temperature of PLA was significantly decreased from 58.7 to 52.1 degrees C with an increase of MPEG-PLA proportion from 0 to 75%, suggesting the miscibility of PLA and MPEG-PLA. The pure PLA nanoparticles (100/0) exhibited the slowest drug-release rate with 37.3% encapsulated drug released from the nanoparticles for 14 days while the MPEG-PLA nanoparticles (0/100) achieved the fastest drug release with 95.9% drug release in the same period.

Antineoplastic Agents, Phytogenic↗

PubMed1992

Poly(ethylene oxide)-graft-poly(L-lysine) copolymers to enhance the biocompatibility of poly(L-lysine)-alginate microcapsule membranes.

A graft copolymer having poly(L-lysine) (PLL) as the backbone and monomethoxy poly(ethylene glycol) (MPEG) as pendent chains was synthesized. This polycationic copolymer was used to form microcapsules with sodium alginate, a polyanion. Microcapsules and model surfaces formed with PLL-graft-MPEG demonstrated reduced protein adsorption, complement binding and cell adhesion in vitro compared to materials with unmodified PLL. Microcapsules with PLL-g-MPEG on the surface were seen to be much more biocompatible than the widely used alginate/PLL/alginate microcapsule in a mouse intraperitoneal implant model. The graft copolymers demonstrated a lower affinity for alginate and increased microcapsule permeability more than PLL. To correct this, pentalayered alginate/PLL/alginate/PLL-g-MPEG/alginate microcapsules were fabricated, and these demonstrated both appropriate permselectivity and enhanced biocompatibility.

Adsorption↗