Synthesis of polystyrene nanospheres having lactose-conjugated hydrophilic polymers on their surfaces and carbohydrate recognition by proteins

We prepared a poly(vinylamine)-grafted polystyrene nanosphere by the free radical polymerization of poly(N-vinylacetamide) macromonomer and styrene with AIBN in ethanol and subsequent acid hydrolysis. We conjugated lactose on the nanosphere by an amide linkage and found that the lactose was recognized by a galactose-specific lectin RCA120, which was analyzed by enzyme-linked lectin assay (ELLA). The binding ability of the lectin to lactose on the nanosphere was at least 10(2) times larger than that to a monomeric lactose. Binding ability was clearly affected by the lactose density on the nanosphere and showed a maximum value at the suitable surface density of lactose. We found that the carbohydrate-conjugated nanosphere would be a useful biomaterial for a site specific drug carrier.

A study on hydroxyapatite formation on/in the hydroxyl groups-bearing nonionic hydrogels

Using the biomimetic method, we formed a hydroxyapatite (HAp) layer on/in certain types of nonionic hydrogels that contain hydroxyl groups. The hydrogels used were poly(vinyl alcohol) (PVA), poly(2-hydroxyethyl methacrylate) (PHEMA), poly(glucosyloxyethyl methacrylate) (PGEMA), and agarose. Under an optical microscope, we observed a thin, continuous HAp layer on the top surface of the PVA, PHEMA, and PGEMA gels. On the other hand, we only observed an intermittent HAp layer on the surface of the agarose gel. The swelling ratio and the bound water content of these hydrogels were measured as an essential character in HAp formation. There was some relation among the HAp formation, the swelling ratios, and the bound water content.

p21WAF1 expression by an activator of protein kinase C is regulated mainly at the post-transcriptional level in cells lacking p53: important role of RNA stabilization

p21(WAF1) inhibits cyclin-cyclin-dependent kinase (Cdk) complexes, causing cell cycle arrest. p21(WAF1) contains p53-binding sites in its promoter and expression of p21(WAF1) is induced by functional p53. In the present work, we have studied the role of protein kinase C (PKC) in the induction of p21(WAF1) and show that induction of p21(WAF1) expression can occur by activation of PKC in cells having no p53. Human ovarian carcinoma cells, SKOV-3, lack p53 protein and PMA, a potent activator of PKC, did not induce p53. PMA increased the expression of p21(WAF1) mRNA both in these cells and in other cells which do not contain p53 (THP-1 and U937). Treatment of human embryonic fibroblasts, WI38, with PMA also induced the accumulation of p21(WAF1) without affecting p53 levels. However, PMA did not increase levels of p21(WAF1) mRNA in cells where either the PKC or the mitogen-activated protein kinase pathway was blocked. Furthermore, treatment of cells with various phorbol ester derivatives which activate PKC resulted in the induction of p21(WAF1) in SKOV-3 cells. In contrast, phorbol esters which do not activate PKC failed to induce p21(WAF1) expression. PMA increased the transcriptional rate of p21(WAF1) and activated the transcription of a luciferase reporter gene, controlled by the p21 promoter, in SKOV-3 cells with or without a p53 consensus-binding sequence. By contrast, PMA markedly stabilized p21(WAF1) mRNA; the half-life (t1/2) of p21(WAF1) in PMA-treated cells was >8 h compared with <1 h in untreated cells. These findings provide evidence that the PKC pathway induces expression of p21(WAF1) independently of p53. Our present study also suggests that the accumulation of p21(WAF1) transcripts by PMA occurs mainly at post-transcriptional level.

Mucoadhesion of polystyrene nanoparticles having surface hydrophilic polymeric chains in the gastrointestinal tract

The mucoadhesion of polystyrene nanoparticles having surface hydrophilic polymeric chains in the gastrointestinal (GI) tract was investigated in rats. Radiolabeled nanoparticles were synthesized by adding hydrophobic 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine in the final process of nanoparticle preparation. The radioiodonated diazirine seemed to be incorporated in the hydrophobic polystyrene core of nanoparticles. The incorporation rate was less than 10%, irrespective of nanoparticle type. The diazirine incorporated in nanoparticles exhibited little leakage from them even though they were mixed with a solution corresponding to GI juice. The change in blood ionized calcium concentration after oral administration of salmon calcitonin (sCT) with nanoparticles showed that the in vivo enhancement of sCT absorption by radiolabeled nanoparticles was the same as that by non-labeled nanoparticles. The GI transit rates of nanoparticles having surface poly(N-isopropylacrylamide), poly(vinylamine) and poly(methacrylic acid) chains, which can improve sCT absorption, were slower than that of nanoparticles covered by poly(N-vinylacetamide), which does not enhance sCT absorption at all. These slow transit rates were probably the result of mucoadhesion of nanoparticles. The strength of mucoadhesion depended on the structure of the hydrophilic polymeric chains on the nanoparticle surface. The mucoadhesion of poly(N-isopropylacrylamide) nanoparticles, which most strongly enhanced sCT absorption, was stronger than that of ionic nanoparticles, and poly(N-vinylacetamide) nanoparticles probably did not adhere to the GI mucosa. These findings demonstrated that there is a good correlation between mucoadhesion and enhancement of sCT absorption.

Concanavalin A-immobilized polystyrene nanospheres capture HIV-1 virions and gp120: potential approach towards prevention of viral transmission

To establish an effective tool for the prevention of HIV-1 transmission, lectin-immobilized polystyrene nanospheres were synthesized and examined for their HIV-1 capture activity. When concanavalin A (Con A) was immobilized on the surface of polystyrene nanospheres (400 nm in diameter) with poly(methacrylic acid) branches and incubated with HIV-1 suspension at room temperature for 60 min, the nanospheres (Con A-NSs) achieved a >3.3 log and a 2.2 log reduction of viral infectivity in HIV-1 (IIIB strain) suspension at a concentration of 2 and 0.5 mg/ml, respectively. Meanwhile, Con A-free nanospheres, which were not immobilized with Con A, achieved only a 0.29 log reduction at 0.5 mg/ ml. Con A-NSs (2 mg/ml) could also reduce the gp120 level of III(B) and HE strains to <7.1% and 5.5% of each control, respectively. The combination of Con A-NS treatment followed by filtration with a microporous membrane efficiently removed virion-free gp120 as well as infectious viral particles from HIV-1 suspension. Electron microscopic examination demonstrated that HIV-1 virions were trapped on the surface of Con A-NSs. Thus, Con A-NSs can capture HIV-1 virions and gp120 with high affinity, and may have potential as an effective tool for the prevention of HIV-1 transmission.

Anticoagulant and antiprotease activities of a heparinoid sulfated glucoside-bearing polymer

We studied anticoagulant and antiprotease activities of the poly(glucosyloxyethyl methacrylate) sulfate [poly(GEMA)-sulfate] in plasma and purified enzyme systems in order to evaluate the anticoagulant behavior of a heparin-like sulfated glucoside-bearing polymer. As a result, we found that poly(GEMA)-sulfate can inhibit some coagulation proteases, although its antiprotease behavior differed from those of heparin and dextran sulfate. Poly(GEMA)-sulfate could not enhance antithrombin activity; therefore, we did not observe any significant inhibition of Factor Xa via antithrombin. However, we found that poly(GEMA)-sulfate was able to inhibit thrombin through the activation of heparin cofactor II. In addition, poly(GEMA)-sulfate was able to inhibit Tenase. In our previous research. we found that the anticoagulant activity of poly(GEMA)-sulfate is due primarily to the formation of an insoluble complex with fibrinogen. This paper showed that the antiprotease activities of poly(GEMA)-sulfate contribute to some extent to its anticoagulant activity.

Control of endotoxin shock by the dried preparation of low virulent Streptococcus pyogenes OK-432

Bacterial endotoxin, lipopolysaccharide (LPS), is a causative agent of Gram-negative septic shock. However, if preadministered at a low dose, LPS makes mice resistant to subsequent endotoxin challenge, the phenomenon known as LPS tolerance. Here we demonstrated that the pharmaceutical preparation of Gram-positive Streptococcus pyogenes, OK-432, also induced a state analogous to LPS tolerance if administered 6-48 h prior to LPS challenge. The preadministration of OK-432 increased the lethal dose of LPS threefold in BDF1 mice, and this was accompanied by reduced gene expression of IL-6, IFN-gamma, inducible nitric oxide synthase, and IL-10 in spleen and peritoneal cells. Serum concentrations of IL-6 and IFN-gamma were also suppressed by the preadministration of OK-432. In contrast to the LPS tolerance, the levels of TNF-alpha mRNA were not suppressed in OK-432-administered mice, and their peritoneal cells produced high levels of TNF-alpha and soluble TNF receptor p75 in response to LPS in vitro. Peritoneal cells from OK-432 but not LPS-administered mice were hyporesponsive to IFN-gamma in terms of nitric oxide synthesis, and this hyporesponsiveness to IFN-gamma was abrogated by anti-IL-10 antibodies. Likewise, peritoneal cells from both OK-432- and LPS-administered mice were hyporesponsive to LPS, serum, TNF-alpha, IFN-gamma, and PMA in terms of IL-6 production. Anti-IL-10 antibodies increased IL-6 production eightfold in cells from OK-432-administered mice, but marginally in cells from LPS-administered mice. Even in peritoneal cells from OK-432-administered mice, anti-IL-10 antibodies failed to fully restore IL-6 production. Thus, the hyporesponsive state of peritoneal cells was mediated by both IL-10-dependent and -independent mechanisms. These results demonstrated that OK-432 controlled endotoxin shock by blocking the cytokine cascade from TNF-alpha.

Preparation of a novel functional hydrogel consisting of sulfated glucoside-bearing polymer: activation of basic fibroblast growth factor

Sulfated poly(glucosyloxyethyl methacrylate) [poly(GEMA)-sulfate] and its hydrogel were synthesized and evaluated to develop novel tissue regeneration assist devices. The poly(GEMA)-sulfate hydrogel was obtained by gamma-ray irradiation. Basic fibroblast growth factor (bFGF) was expected to be subsequently incorporated with hydrogel matrices and activated or released from the matrices. A sustained release of bFGF from the poly(GEMA)-sulfate hydrogel was not realized; however, bFGF from poly(GEMA)-sulfate hydrogel was effectively activated. Poly(GEMA)-sulfate hydrogels are thought to be potential component materials for a tissue engineering matrix.

Inhibition in a microgravity environment of the recovery of Escherichia coli cells damaged by heavy ion beams during the NASDA ISS phase I program of NASA Shuttle/Mir mission no. 6

We participated in a space experiment, part of the National Space Development Agency of Japan (NASDA) Phase I Space Radiation Environment Measurement Program, conducted during the National Aeronautics and Space Administration (NASA) Shuttle/Mir Mission No. 6 (S/MM-6) project. The aim of our study was to investigate the effects of microgravity on the DNA repair processes of living organisms in the <Realtime Radiation Monitoring Device III (RRMD III)> in orbit. Heavy ion beam radiation- or ç-irradiation-damaged biological samples of Escherichia coli and the radioresistant bacterium Deinococcus radiodurans were prepared and placed in a biospecimen box, which was loaded into the RRMD III sensor unit of the Space Shuttle. Two identical sets of samples were left in the Spacehab's Payload Processing Facility (SPPF) in Florida, USA, as a control. (flight No. STS-84) was launched from NASA John F. Kennedy Space Center (KSC) in Florida, USA, on May 15, 1997. The mission duration was 9.22 days. An astronaut activated the biological samples in the biospecimen box in the Spacehab during orbit in order to start repair of the DNA damaged by heavy ion beams or ç-irradiation and the samples were incubated for 19 h 35 min at about 22ûC, the cabin temperature. The control specimens in the SPPF were subjected to the same treatment under terrestrial gravity. After returned to earth, we investigated cell recovery by comparing the repair of the radiation-damaged DNA of E. coli and D. radiodurans in the microgravity environment in space with that on Earth. The results indicated that the DNA repair process of E. coli, but not of D. radiodurans, cells was inhibited in a microgravity environment.

Evaluation of biological responses to polymeric biomaterials by RT-PCR analysis III: study of HSP 70, 90 and 47 mRNA expression

In this study, in order to analyze how cells recognize biomaterials, mRNA was evaluated on various substrates as shown in the attached HeLa S3 cells. The expressed Heat-Shock Protein (HSP) 70A, 70B, 90 and 47 mRNA were isolated and detected using the RT-PCR method. As a result, 70B, 90 and 47 mRNA expressions varied with differences in the hydrophilicity hydrophobicity of the substrates. HSP mRNAs outcome was induced significantly in the HeLa S3 cells that had adhered onto the hydrophilic surfaces. On the other hand, in the cells that had adhered to the hydrophobic surfaces, HSP mRNAs expressions were low. In the non-adhered HeLa S3 cells the tendency found in HSP 70B and HSP 47 mRNA's expressions was the same as that found in adhered cells, while there were no significant differences in the HSP 90 mRNA expression among either of the samples. We have concluded that HSP mRNAs expression is an important marker in the study of cell-polymer interactions.

Li-Fraumeni syndrome and the role of the p53 tumor suppressor gene in cancer susceptibility

Mutation of the tumor suppressor gene p53 is a molecular genetic event frequently observed in human cancer, and inactivating missense mutations usually are accompanied by the resultant overexpression of mutant p53 protein. In gynecologic cancers, p53 is also often altered; the frequency varies depending on types of cancers and where they develop. Further, human papillomavirus oncoproteins that inactivate p53 and Rb proteins play important roles in the development of several gynecologic cancers. Individuals who are heterozygous for germline mutations of the p53 gene are strongly predisposed to a variety of cancers. The identification of these individuals may have profound value in the future when therapies or chemopreventive agents specific for the p53 alteration are available. The role of p53 tumor suppressor gene in gynecologic cancers and heritable cancer susceptibility syndromes including Li-Fraumeni and Lynch II syndromes is an active and important area of study.

Base-specific separation of oligodeoxynucleotides by capillary affinity gel electrophoresis

Capillary affinity gel electrophoresis was applied to sequence-specific and base composition-specific recognition of oligodeoxynucleotides, utilizing the formation of heteroduplexes between a nucleic acid analogue immobilized into the capillary gel and soluble oligodeoxynucleotides with different sequences. Capillary affinity gel electrophoresis using capillaries filled with a conjugated gel of polyacrylamide and a synthetic nucleic acid analogue [poly(9-vinyladenine)] was effective for the selective separation of hexathymidylic acid from a mixture of four homopolymers of A6, C6, G6, and T6 and for the complete resolution of five heteropolymers of hexadeoxynucleotides (TAAAAA, TTAAAA, TTTAAA, TTTTAA, TTTTTA). We also demonstrated that capillary affinity gel electrophoresis was useful for the selective and the sensitive sequence-specific recognition of sequence isomers of DNA (TTTTAA, TTTTAAT, TTTATA, and TTTTAA).

Capture of HIV-1 gp120 and virions by lectin-immobilized polystyrene nanospheres

A lectin such as concanavalin A (Con A) was immobilized on the surfaces of poly(methacrylic acid) branches covered with polystyrene nanospheres with a diameter of 360 nm, which were obtained by the free radical copolymerization of styrene with the poly(tert-butylmethacrylate) macromonomer, followed by hydrolysis. Using Con A-immobilized (0.3 microgram/cm2) nanospheres, the interaction of the nanospheres with HIV-1 was determined by the reduction of the gp120 level and the viral infectivity of the HIV-1 suspensions after a 60 min incubation at room temperatures. Con A-immobilized nanospheres achieved a 95 and a 77% reduction of the gp120 level and the infectivity at a concentration of 0.5 mg/mL, respectively, indicating the effective capture of the gp120 and the virions.

Endogenous production of tumour necrosis factor is required for manganese superoxide dismutase expression by irradiation in the human monocytic cell line THP-1

Manganese superoxide dismutase (MnSOD) is a mitochondrial enzyme that scavenges superoxide (O2-) ions. We studied the regulation of MnSOD gene expression by irradiation and the mechanisms in human monocytic cell line THP-1. We found that irradiation induced expression of the MnSOD gene through the autocrine mechanism, involving the production of tumour necrosis factor (TNF). Irradiation increased TNF production in THP-1 cells, and TNF increased the levels of MnSOD transcripts. Supernatant from irradiated THP-1 cells induced the expression of MnSOD mRNA, and anti-TNF antibody blocked the induction of MnSOD mRNA. Irradiation also increased the levels of MnSOD mRNA in other myelocytic cell lines, HL60 and KG-1, and the ovarian cancer cell line SK-OV-3. Moreover, increased levels of MnSOD mRNA were observed in mature myeloid cells, including macrophages and granulocytes, as well as in immature cells. However, irradiation did not increase the level of MnSOD mRNA in THP-1 cells with prolonged exposure to PMA. We also found that irradiation increased the rate of MnSOD transcription, and irradiation stabilized MnSOD mRNA in THP-1 cells. Our results indicate that the endogenous production of TNF is required, at least in part, for the induction of MnSOD mRNA expression by irradiation in THP-1 cells, and the increased levels of MnSOD transcripts on irradiation occur through a pathway involving protein kinase C activation. Our results also indicate that the increase in MnSOD mRNA caused by irradiation is regulated by both transcriptional and post-transcriptional mechanisms.

Evaluation of biological responses to polymeric biomaterials by RT-PCR analysis. II: Study of HSP 70 mRNA expression

In order to investigate how cells recognize biomaterials, mRNA that was expressed in attached HeLa S3 cells on various substrates was evaluated. As culture substrates, cellulose, ethylene-vinyl alcohol copolymer (EVAL), nylon, tissue culture polystyrene (TCPS), high-density polyethylene (PE), silicone rubber, and tetrafluoroethylene-hexafluoropropylene copolymer (6F) were used. HeLa S3 cells were cultured on these substrates for 24 h. The expressed HSP 70s mRNA was then isolated and detected using the RT-PCR method. As a result, the expression of HSP 70B mRNA was largely induced in cells that adhered to hydrophilic surfaces. On the other hand, on hydrophobic surfaces, the HSP 70B mRNA expression was low. It is concluded that HSP 70B mRNA expression is sensitive to differences in the hydrophilicity-hydrophobicity of the substrates.

The mechanism of anticoagulant activity of a novel heparinoid sulfated glucoside-bearing polymer

In our previous study on glycoside polymer, it was discovered that sulfated poly(glucosyloxyethyl methacrylate) [poly(GEMA)-sulfate], which bears sulfated D-(+)-glucose, exhibited anticoagulant activity. The anticoagulant activity of poly(GEMA)-sulfate in solution was prolonged by increasing the dose or degree of sulfation of the polymer. In this study, to recognize the mechanism of anticoagulant activity of poly(GEMA)-sulfate, we estimated the binding capacity of antithrombin III to thrombin and some in vitro clotting tests in the presence of poly(GEMA)-sulfate. These results revealed that poly(GEMA)-sulfate had an anticoagulant mechanism which differed to that of heparin. We concluded that the anticoagulant activity of poly(GEMA)-sulfate is responsible for inhibiting fibrin network formation by the insoluble ion complex between fibrinogen and poly(GEMA)-sulfate.

Anti-cancer agent OK432 induces manganese superoxide dismutase in human granulocytes

Manganese superoxide dismutase (MnSOD) is a mitochondrial enzyme involved in scavenging O2-. OK432, a Streptococcal preparation, has anti-tumor activity and is also known to be a biological-response modifier. In this study, we have examined the regulation of MnSOD gene by OK432 in human granulocytes. Granulocytes had a low activity of MnSOD; OK432 increased MnSOD mRNA levels in a dose-dependent manner and its activity in granulocytes. OK432 also induced the MnSOD mRNA in HL60 promyelocytes, while not affecting the levels of MnSOD mRNA in human fibroblasts. Pre-treatment with either actinomycin D or cycloheximide inhibited the induction of MnSOD mRNA by OK432. OK432 increased the levels of interleukin-1 (IL-1) and tumor-necrosis-factor-alpha (TNFalpha) mRNA in granulocytes. Furthermore, the induction of MnSOD mRNA by OK432 was blocked by anti-IL-1 antibody but not by anti-TNF antibody. These results suggest that the induction of MnSOD mRNA by OK432 is regulated at the transcriptional level, and OK432 induces MnSOD mRNA, at least in part, through production of IL-1 in granulocytes.