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PubMed1987

Stimulation of collagenase production in human synovial fibroblast cultures by poly (I). poly (C).

Poly (I). poly (C) was found to induce collagenase secretion in both "normal" and "rheumatoid" synovial fibroblast cultures. Induction was time dependent, was maximal at 20-50 micrograms/ml poly (I). poly (C) and was dependent on de novo synthesis. Induction was prevented by hydrocortisone (0.1 microgram/ml) but inhibition of prostaglandin E production by diclofenac (0.2 microgram/ml) or ibuprofen (0.1 microgram/ml) did not affect collagenase production. Collagenase induction was accompanied by stimulation of hyaluronic acid and prostaglandin E production. This in vitro system may represent a model for the study of pathological secretory activities in the inflamed joint.

Cell Line↗
PubMed1987

[Proteins induced by the double-stranded interferon inducer poly(I).poly(C)].

The possible pathways for realization of antiviral activity of interferon inducer poly (I).poly(C) have been studied. The stimulating effect of interferon inducer on the net protein synthesis in human M19 fibroblasts has been demonstrated. Compositions of the specific proteins induced by poly(I).poly(C) or interferon in human M19 fibroblasts and in monkey cells 4647 have been analyzed by electrophoresis technique. The data obtained suggest the existence of common gene products for interferon and ds-inducer. The ds-inducer requires the synthesis of lesser amounts of proteins for realization of its biological activity as compared with interferon.

Animals↗
PubMedDate not supplied

[Structure of poly(dA).poly(dT) from data of x-ray diffraction, energy calculations and nuclear magnetic resonance].

The results of X-ray diffraction studies of poly(dA).poly(dT) have been compared with the results of energy optimization and with the NMR data in solution. Slight refinement of the X-ray and energetically optimal models leads to a very good quantitative agreement with the NMR data, that suggests similarity of the poly(dA).poly(dT) structure in a condensed state and in solution. One of the features distinguishing these models from the classic B form is a narrowed minor groove of the double helix. The anomalous properties of DNA with this sequence can be related specific organization of the water molecules near the polynucleotide.

Magnetic Resonance Spectroscopy↗
PubMed1986

A new procedure to immobilize polyriboinosinic-polyribocytidylic acid (poly I:C) on the surface of polymethylmethacrylate and the use of poly I:C in clinical hemoperfusion.

A new procedure for covalent immobilization of polyriboinosinic-polyribocytidylic acid (poly I:C) on the surface of polymethylmethacrylate (PMMA) is described. Carboxyl groups are generated on the PMMA surface and react with primary amino groups of cytosine. These amino groups are made accessible by heating. The original polynucleotide structure is partly reformed on cooling. An extracorporeal chamber for in vivo whole blood perfusion made from PMMA has been previously described. Such chambers activated as described above by poly I:C have been used clinically. Considerable increase of cytotoxicity activity was observed and was long-lasting. No significant toxic side effects occurred and no refractoriness ensued during intermission between treatment periods. The same poly I:C chamber could be used several times in the same patient without loss of activity. Controls showed no leakage from the poly I:C mono-layer on the PMMA surfaces.

Adult↗
PubMed1980

Induction of poly(I):poly(C)-binding 50 K protein and 2',5'-oligoadenylate synthetase in interferon-treated mouse L929 cells.

A new protein retained by poly(I):poly(C)-Sepharose was induced together with dsRNA-dependent enzymatic activities, a protein kinase and 2',5'-oligoadenylate synthetase (2,5A synthetase), in interferon-treated mouse L929 cells; it had an apparent molecular weight of 50,000 (50 K) and was not phosphorylated by the protein kinase. The kinetics of the induction of the poly(I):poly(C)-binding 50 K protein were similar to those of dsRNA-dependent protein kinase and 2',5'-oligoadenylate synthetase, and their inductions were all dependent on the interferon dose added, though a relatively higher dose was required for the 50 K protein. When the interferon preparation was heated to 100 degrees C in the presence of sodium dodecyl sulfate, its effect on cells of inducing the activity of 2',5'-oligoadenylate synthetase was preserved completely, indicating that the interferon molecule itself is responsible for the induction of the synthetase. Since the induction of the enzymatic activity was inhibited by addition of either actinomycin D or cycloheximide, it may not be an activation of a latent enzyme but a de novo synthesis of the enzyme.

2',5'-Oligoadenylate Synthetase↗
PubMed1984

[Transport of 125I-poly I : poly C incorporated in liposomes from the enteric cavity to the small intestine mucosa. An electron microscopic autoradiographic study].

Transport of 125I-poly(I) : poly(C) incorporated into liposomes trough the small intestine mucose was investigated by electron microscopic autoradiography. With the migration of liposomes into the mucous layer on the luminal surface of the intestine up to the glycocalix level of microvilli these undergo degradation with the formation of monolayer liposomes from which polynucleotide is released. Later on the poly(I) : poly(C) or its fragments transported through the enterocytes to be accumulated in cells of the connective tissue stroma of the small intestine mucose. Part of polynucleotide was incorporated up to the arterial and lymphoid capillary level. Apparently, on the way of its transport the polynucleotide is affected by pancreatic and tissue nucleases. The accumulation of polynucleotide in macrophages, fibroblasts, lymphocytes, plasma cells and smooth muscle cells was traced. It is supposed that the polynucleotide accumulated in stroma of the small intestine mucose may preserve its interferon inducing activity.

Animals↗
PubMedDate not supplied

[Comparative study of the effectiveness of the interferon inducers, poly(I) : poly(C) and GSS (gossypol-beta-aminoethylsodium sulfate), in combination with a specific vaccine in experimental infection with the human acute encephalomyelitis virus].

Using the model of human acute encephalomyelitis virus (HAEM) infection it was found that inoculation of mice with interferon inducers poly(I): poly(C) or GSS at the site of virus inoculation prevented the lethal outcome of the infection. The effectiveness of the inducers increased markedly when used in combination with the specific vaccine against HAEM virus. Both with inducers alone and in combination with the vaccine, the level of mouse protection in experiments with poly(I): poly(C) was higher than in those using GSS. The higher level of protection achieved by the administration of the inducers and the vaccine was shown to be due both to interferon production and activation of cellular immunity mechanisms.

Animals↗
PubMed1998

Functional interactions of p53 with poly(ADP-ribose) polymerase (PARP) during apoptosis following DNA damage: covalent poly(ADP-ribosyl)ation of p53 by exogenous PARP and noncovalent binding of p53 to the M(r) 85,000 proteolytic fragment.

We have examined the domain-specific interactions between p53 and poly(ADP-ribose)polymerase (PARP) (E.C. 2.4.2.30) in apoptotic HeLa cells. Apoptosis was induced by exposing cells to 50 microM N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for increasing lengths of time and was confirmed by: (a) oligonucleosomal fragmentation of chromatin; (b) increase in p53 levels; and (c) degradation of PARP into the characteristic M(r) 85,000 (COOH-terminal catalytic domain) and M(r) 29,000 (DNA-binding domain) peptide fragments. We also immunodetected p53 in immunoprecipitates obtained with a PARP-specific antibody. However, intact PARP coimmunoprecipitated with a p53-specific antibody during the initial 30 min of MNNG treatment. After 60 min, only the COOH-terminal fragment coimmunoprecipitated with p53, indicating that PARP noncovalently binds p53 via its M(r) 85,000 catalytic domain. Therefore, we next examined p53 as a covalent target for poly(ADP-ribosyl)ation. Although p53 was not endogenously poly (ADP-ribosyl)ated in situ, incubation of cell extracts with full-length PARP from calf thymus and [32P]beta NAD+ resulted in its time-dependent poly(ADP-ribosyl)ation. In summary, our results are consistent with the conclusion that PARP and p53 are activated with nonoverlapping kinetics during apoptosis.

Apoptosis↗
PubMed1998

Differential synthesis of cholesterol esterase by monocyte-derived macrophages cultured on poly(ether or ester)-based poly(urethane)s.

Monocytes adherent to implanted biomaterials differentiate into macrophages while synthesizing large amounts of degradative enzymes, including cholesterol esterase (CE), which previously has been shown to degrade poly(urethane)s. Human peripheral blood monocytes were cultured on tissue culture grade polystyrene (PS), and two model poly(urethane)s were synthesized from (1) polycaprolactone (PCL) and (2) polytetramethylene oxide (PTMO), both with 2,4-toluene diisocyanate (TDI) and ethylene diamine (ED). The increase in CE and total protein per cell were measured on days 8 and 28 in culture and normalized to the DNA content per cell. At day 8 there consistently were fewer cells remaining on the PTMO-based polymer than on the PCL-based polymer or the PS (p < 0.05). When comparing day 28 to day 8, there was more CE activity and protein per cell on all materials. However, there was a disproportionate synthesis of CE per mg of total protein on PS and TDI/PCL/ED whereas on PTMO there was not. Significantly, there was more protein and CE per cell on PTMO than on PS or TDI/PCL/ED (p < 0.05). This in vitro model system of the chronic phase of inflammation has shown that it is possible to culture monocytes for a month and assess the material surface itself as a potent activator of the differentiation into macrophages without secondary stimulation. Since CE has been shown to degrade poly(ether and ester)-based poly(urethane)s, the differential production of this enzyme relative to the total protein on different surfaces may impact on the potential long-term biostability of an implanted material.

Biocompatible Materials↗
PubMed2000

Biocompatibility and effect on osteogenesis of poly(ortho ester) compared to poly(DL-lactic acid).

Implantation of demineralized bone induces new bone formation by the action of contained growth factors, of which bone morphogenetic proteins are of prime importance. A biodegradable polymer may be used as a carrier for demineralized bone particles or recombinant bone growth factors to prevent displacement of the implant, preserve its volume and shape, and assure sustained release of the incorporated active components. A polymer for this use should be biocompatible and completely absorbed without interfering with the osteogenesis. We investigated the host-tissue response and effect on demineralized bone-induced bone formation by two biodegradable polymers, a poly(ortho ester) and an amorphous low-molecular poly(DL-lactic acid). Both polymers had a plastic consistency, could easily be molded, and adhered well to the demineralized bone particles. Demineralized bone particles were implanted alone and in combination with each of the polymers in the abdominal muscles of 45 male Wistar rats. Four weeks after the operation the implants were recovered and subjected to (85)Sr uptake analysis to quantify bone formation and histologic examination. The poly(ortho ester) provoked little inflammation; it was largely absorbed by 4 weeks, and no qualitative or quantitative effect on bone formation was found. The poly(DL-lactic acid) provoked a chronic inflammation with multinuclear giant cells, macrophages with engulfed material, and proliferating fibroblasts; part of the material was still present, and the bone formation was inhibited.

Animals↗
PubMed2003

Nonadhesive nanotopography: fibroblast response to poly(n-butyl methacrylate)-poly(styrene) demixed surface features.

It is becoming clear that cells do not only respond to micrometric scale topography, but may also respond to topography at the nanometric scale. Nano-fabrication methods such as electron beam lithography are, however, expensive and time consuming. Polymer demixing of poly(styrene) and poly(4-bromostyrene) has been found to produce nano-scale islands of reproducible height, and the islands have been previously shown to effect cell events such as adhesion, spreading, proliferation, and differentiation. This study uses demixed poly(styrene) and poly(n-butyl methacrylate) to produce nano-islands with closer packing and narrower widths compared with those previously studied. Observations have been made of morphological and cytoskeletal changes in human fibroblasts interacting with 10- and 50-nm-high islands. The methods used included scanning electron microscopy, fluorescent microscopy, and optical microscopy. The results indicated that the cells do not respond differently to the 10-nm islands compared with planar samples but, in contrast, the 50-nm islands are nonadhesive.

Biocompatible Materials↗
PubMed2005

pH effects on the complexation, miscibility and radiation-induced crosslinking in poly(acrylic acid)-poly(vinyl alcohol) blends.

The effect of pH on the complexation of poly(acrylic acid) with poly(vinyl alcohol) in aqueous solution, the miscibility of these polymers in the solid state and the possibility for crosslinking the blends using gamma radiation has been studied. It is demonstrated that the complexation ability of poly(vinyl alcohol) with respect to poly(acrylic acid) is relatively low in comparison with some other synthetic non-ionic polymers. The precipitation of interpolymer complexes was observed below the critical pH of complexation (pH(crit1)), which characterizes the transition between a compact hydrophobic polycomplex and an extended hydrophilic interpolymer associate. Films prepared by casting from aqueous solutions at different pH values exhibited a transition from miscibility to immiscibility at a certain critical pH, pH(crit2), above which hydrogen bonding is prevented. It is shown here that gamma radiation crosslinking of solid blends is efficient and only results in the formation of hydrogel films for blends prepared between pH(crit1) and pH(crit2). The yield of the gel fraction and the swelling properties of the films depended on the absorbed radiation dose and the polymer ratio. [Diagram: see text] SEM image of an equimolar PAA-PVA blend cast from a pH 4.6 solution.

Acrylic Resins↗
PubMed1998

Polymorphism and disorder of poly(dA).poly(dT) in fibers.

The absence of proportionality between fiber length and interbase axial distance reveals a high degree of disorder in fibers of poly(dA).poly(dT) when the relative humidity (r.h.) varies. According to X-ray patterns, the increase of fiber length does not correspond to any conformational change. The B' structure is present alone and in a better-organized form at higher r.h. We noted a dependence of length values on the direction of variation of the r.h. An unusual minimum of fiber length is observed around 65% r.h. and explained as been due to an amorphous part of the fiber, essentially composed of single strands of poly(dA) and poly(dT). At a temperature higher than 30 degrees C, the transition B'(alpha)-B* takes place but is associated with an important decrease of fiber length in spite of constancy of the helical rise per base pair. It is shown that this behavior is also due to the amorphous part of the fiber and not to a conformational transition.

Models, Chemical↗
PubMed1990

Poly[d(C-A)].poly[d(G-T)] is highly transcribed in the testes of Drosophila hydei.

Microdissection of the lampbrush loops "threads" and "pseudonucleolus" of Y chromosomes from primary spermatocytes of Drosophila hydei and subsequent microcloning of the DNA yielded several recombinant DNA clones which cross-hybridized in screening the different clone banks. By DNA sequencing we found that the inserts of these cross-hybridizing clones contain blocks of poly[d(C-A].poly[d(G-T)]. Testis RNA contains a large fraction of transcripts with this simple repeated nucleotide sequence. With the aid of transcript in situ hybridization we discovered that the "cones" and "pseudonucleolus" lampbrush loops are the primary sites of transcription of poly[d(C-A)].poly[d(G-T)] in spermatocytes. In addition, we found a strand-specific transcription of (CA/GT)n. In both the "cones" and "pseudonucleolus" the (CA)n strand is transcribed, while in the "pseudonucleolus" (GT)n is also transcribed. Labelled (CA)n probes also react with the protein bodies in spermatid nuclei. These observations are discussed in the context of possible functions of (CA/GT)n transcripts in spermatogenesis.

Animals↗
PubMed1989

Use of poly(vinylpyrrolidone) and poly(vinyl alcohol) for cryoultramicrotomy.

Specimens infused with or suspended in a mixture of 10-30% poly(vinylpyrrolidone) and 2.07-1.61 M sucrose can often be more easily frozen-sectioned than those infused with sucrose alone. The pH of such a mixture can be efficiently adjusted to neutrality by using Na2CO3. Use of poly(vinylpyrrolidone) causes little or no increase in the background level of immunolabelling. Adsorption staining of ultrathin frozen sections with a mixture of uranyl acetate and poly(vinyl alcohol), i.e. a simple thin-embedding of the sections in such a mixture, produces positive staining effects that are often enough to delineate structures of many organelles. When OsO4-treated frozen sections are stained with uranyl acetate and further adsorption-stained with a mixture of lead citrate and poly(vinyl alcohol), the overall staining effects are similar to those observed in double-stained conventional sections.

Animals↗
PubMed1987

A circular dichroism study of the binding of CC-1065 to B and Z form poly(dl-5BrdC).poly(dl-5BrdC).

CC-1065, Benzo[1,2-b:4,3-b']dipyrrole-3(2H)-carboxamide, 7-[[1,6-dihydro-4-hydroxy-5-methoxy-7-[(4,5,8,8a-tetrahydro-7-methyl-4- oxocyclopropa[c]pyrrolo[3,2-e]indol-2(1H)-yl)carbonyl]benzo [1,2-b:4,3-b']dipyrrol-3(2H)-yl]carbonyl]-1,6-dihydro-4-hydroxy- 5-methoxy-, (7bR,8aS), binds to the B form of poly(dl-5BrdC).poly(dl-5BrdC) to yield a reversibly bound species whose stability with respect to an irreversibly bound species (presumably the inosine N-3 adduct) is much greater than it is for other DNA polymers. Competitive binding experiments with netropsin, show that this reversibly bound species of CC-1065 contains CC-1065 in the minor groove of the double helix. A review of the CC-1065 binding data obtained on other synthetic DNA polymers suggests that the widely different rates of species conversion shown by these polymers may result from small differences in DNA secondary structure rather than from different alkylating abilities of the adenine or inosine N-3 active site. CC-1065 converts the Z-form of poly(dl-5BrdC).poly(dl-5BrdC) in 3.5 M sodium chloride to the B form and does not bind to the Z form in this solvent system. CC-1065 bound to the B form polymer inhibits the formation of the Z form if the helix is saturated with CC-1065. Regions of the polymer without bound CC-1065 can convert to the Z form with added salt, producing a situation where the polymer contains both the B and Z conformations. In 4.0 M sodium chloride, where the Z conformation is also predominate, the addition of CC-1065 causes chiral aggregates to form, and CC-1065 binds to the aggregates. The addition of dimethylformamide in the absence of CC-1065 or a simple dilution of the 4.0 M sodium chloride polymer solution with water also causes aggregation, indicating that the Z form of this polymer in 4.0 M sodium chloride is unstable with respect to an aggregated form.

Antibiotics, Antineoplastic↗
PubMed1985

B-Z transition in poly(dG-dC).poly(dG-dC) in the presence of formaldehyde amino derivatives.

It was shown by circular dichroism that the B-Z transition of poly(dG-dC).poly(dG-dC) in high NaCl concentrations occurred more rapidly in the presence of formaldehyde and Tris. The product of formaldehyde and glycine interaction induces changes in the poly(dG-dC).poly(dG-dC) CD spectral characteristics of a 'B-like' conformation. It is supposed that the B-Z transition occurs without large-scale hydrogen bond breakage.

Circular Dichroism↗
PubMed1989

Raison d'être and structural model for the B-Z transition of poly d(G-C).poly d(G-C).

In DNA oligonucleotides crystallized in the A form, the nucleotides adopt standard conformation except for steps 5'-CpG-3' where reduced base-pair twist and a sliding motion of the base pairs along their long axes causes pronounced interstrand guanine-guanine overlap. As a consequence, torsion angles alpha, beta and gamma are consistently trans, trans, trans instead of the common-gauche, trans, +gauche. This conformation significantly increases the intraresidue distance between the guanine base and the 5'-phosphate group. A molecular model of poly d(G-C).poly d(G-C) built with these structural characteristics in the A form, which we call A2-DNA, shows that rotation of the guanosine sugar into the syn orientation is easily achieved and pushes the base pair across the helix axis. If successive guanosines are changed this way, a smooth transformation occurs to the left-handed Z-DNA. We suggest that A- and A2-DNA forms of poly d(G-C).poly d(G-C) are metastable and that the actual transition is B in equilibrium (A in equilibrium A2) in equilibrium Z-DNA.

Crystallography↗