Cyclopolymerization of cinnamate ester derivatives of alkyl α-(hydroxymethyl) acrylates

Summary Three new monomers for cyclopolymerization were synthesized using phase transfer catalysis of ethyl -(chloromethyl) acrylate (ECMA), t-butyl -(bromomethyl) acrylate (TBBMA) and isobornyl -(bromomethyl)acrylate (IBBMA) with cinnamic acid sodium salt. Bulk and solution polymerization at 70–80°C using AIBN gave soluble cyclopolymers with Mn=13650 and Mw=36540 for the ethyl ester, Mn=47700 and Mw=86900 for the t-butyl ester and Mn=3500 and Mw=4650 for the isobornyl ester monomer. The ester polymerizabilities decreased with increasing substituent bulkiness. FTIR spectra showed ca 30 to 93% cyclic units depending on the concentration of the monomer used in polymerizations. DSC thermograms showed that alkyl group size had little effect on Tg's, with values of 151°C, 156°C, and 164°C for the ethyl, t-butyl and isobornyl esters, respectively.     

The Multiple Gyrotron System on the DIII-D Tokamak

The electron cyclotron heating and current drive complex on the DIII-D tokamak presently comprises six gyrotrons injecting rf power from the low field side at 110 GHz, the 2f _ce resonance at the center of the vacuum chamber. Typical injected rf power is 600–650 kW per gyrotron. The launched rf can be directed over ±20° toroidally to create both co- and counter-current drive and scanned over 40° poloidally to permit the injected rf beams to intersect, and be absorbed at, the second harmonic resonance anywhere in the tokamak upper half plane. The elliptical polarization is controlled so that the desired extraordinary or ordinary modes are excited for any injection geometry. The maximum injected energy on a single plasma shot has been 16.6 MJ for six gyrotrons injecting a total of 3.4 MW for 5 seconds.     

Tandem repeats of Sushi3 peptide with enhanced LPS-binding and -neutralizing activities

Endotoxin, also known as lipopolysaccharide (LPS), is the majormediator of septic shock due to Gram-negative bacterial infection.Chemically synthesized S3 peptide, derived from Sushi3 domainof Factor C, which is the endotoxin-sensitive serine proteaseof the limulus coagulation cascade, was previously shown tobind and neutralize LPS activity. For large-scale productionof this peptide and to mimick other pathogen-recognizing molecules,tandem multimers of the S3 gene were constructed and expressedin Escherichia coli. The recombinant tetramer of S3 (rS3-4mer)was purified by anion exchange and digested into monomers (rS3-1mer).Both the rS3-4mer and rS3-1mer were functionally analyzed fortheir ability to bind LPS by an ELISA-based method and surfaceplasmon resonance. The LAL inhibition and TNF-release test showedthat rS3-1 mer can neutralize the LPS activity as effectivelyas the synthetic S3 peptide, while rS3-4mer displays an enhancedinhibitory effect on LPS-induced activities. Both recombinantpeptides exhibited low cytotoxicity and no haemolytic activityon human cells. This evidence suggests that the recombinantsushi peptides have potential use for the detection, removalof endotoxin and/or anti-endotoxin strategies. Received September 5, 2002; revised June 18, 2003; accepted June 20, 2003.     

In Vitro Photodynamic Activity of N‐Methylated and N‐Oxidised Tripyridyl Porphyrins with Long Alkyl Chains and Their Inhibitory Activity in Sphingolipid Metabolism

A series of N‐methylated and N‐oxidised tripyridyl porphyrins were synthesised, characterised, and their PDT activity was studied with six cell lines. All the tested porphyrins with a long alkyl chain, except one, were more efficient for PDT than an N‐methylated hydrophilic porphyrin and N‐oxidised porphyrin without the long alkyl chain. Generally, N‐methylated tripyridyl porphyrins were more active than those N‐oxidised, but IC₅₀ values for phototoxicity of two N‐oxides, named TOPyP3‐C₁₇H₃₃O and TOPyP3‐C₁₇H₃₅ , were still in the nanomolar concentration range for most of the tested cell lines. However, TOPyP3‐C₁₇H₃₅ did not show phototoxicity on human foreskin fibroblast cells. Two methylated amphiphilic porphyrins, named TMPyP3‐C₁₇H₃₃ and TMPyP4‐C₁₇H_{35 ,} showed significant dark toxicity, whereas none of the oxidopyridyl porphyrins were toxic without light activation. The selected photosensitisers were shown to be apoptosis inducers, and had inhibitory effects on the clonogenic growth of HCT116 and HeLa cells. All three N‐methylated amphiphilic porphyrins significantly reduced the migratory potential of HCT116 cells. Porphyrins TMPyP3‐C₁₇H₃₅ and TOPyP3‐C₁₇H₃₅ reduced the activity of acid ceramidase, whereas TOPyP3‐C₁₇H₃₃O had a significant inhibitory effect on sphingosine kinase 1 activity in HeLa cells. Compounds with this dual activity were shown to be the most promising photosensitisers, with potential to treat invasive cancers.     

Study on gingival tissue reaction to the materials used for making dental prosthesis

Fixed prosthetic restorations may generate periodontal irritation by various and complex mechanisms especially in the presence of the microbial factor. In this regard, changes that compromise the functional value of the support structures of the teeth occur. Studies on patients wearing fixed denture show that those prosthetic structures facilitate plaque accumulation. Close supervision leads to prevention of periodontal diseases, through learning of a proper hygiene. Between the marginal periodontium and the prosthetic restoration, there must be a relation of ‘mutual protection’ or at least ‘mutual respect’. In this study, we tried to analyze the reaction of the periodontal tissue in contact with fixed prosthesis depending on the prosthetic material used. There were 102 fixed prostheses considered by this study that have generated reactions in the periodontal tissues with which came into contact. Thus, from the total number of 102 fixed dental prostheses, 75% were made from metal alloys based on copper, 18% from Cr–Ni alloys, 2% from Cr–Co alloys, 4% from gold alloys, and one from stainless steel. In 35% of the cases, the patients had multiple fixed dentures made from different types of dental alloys, cases in which the symptoms of the periodontal problems may be also linked to the phenomenon of oral galvanism. The histological study showed various morphological changes from one patient to another, depending on the intensity of the inflammatory and reparative response, the associated diseases (diabetes, dyslipidemia, cardiovascular diseases) and especially on the dental hygiene status. Fixed prosthesis, in the absence of a proper cervical adaptation and an adequate local hygiene, may act as an irritative thorn and may induce gingivitis and periodontitis phenomena.     

Polymerization of olefins with bulky substituents. 1. Homo- and copolymerization of 3-(1-adamantyl)propene

The use of bulky substituents like adamantane has been shown in the past to influence the glass transition temperatures of polymers significantly. In this paper the synthesis and homopolymerization of the monomer 3-(1-adamantyl) propene is described, as well as the copolymerization of this monomer with ethene, propene, 1-pentene, 4-methyl-1-pentene, 1-hexene and 1-octene. The resultant copolymers proved to be largely insoluble in organic solvents. It was also demonstrated that the presence of the bulky methyladamantyl side group influenced the glass transition temperatures of the copolymers in comparison with the corresponding homopolymers.     

Synthesis and photopolymerizations of new hydroxyl-containing dimethacrylate crosslinkers

Two new hydroxyl-containing di(meth)acrylate monomers were synthesized from the reaction of methyl α-chloromethylacrylate (MCMA) and of ethyl α-chloromethylacrylate (ECMA) with glycerol. The monomers were obtained as mixtures of two isomers in different ratios and in combination with the analogous trimethacrylate monomers. Each monomer was isolated by column chromatography. The photopolymerization of these isomer mixtures and the trimethacrylate monomers was investigated individually by photodifferential scanning calorimetry (photoDSC) at room temperature using 2,2′-dimethoxy-2-phenyl-acetophenone (DMPA) as a photoinitiator. The effect of hydrogen bonding on the rates of polymerizations and conversions was examined. The results obtained for the synthesized monomers were compared to the values obtained for commercial monomers. It was observed that the hydroxyl-containing dimethacrylates polymerize much faster and to considerably higher conversion than the trimethacrylate monomers. The maximum rates of polymerization of the hydroxyl-containing monomers were higher than that of the hexanediol dimethacrylate (HDDMA), comparable to glycerol dimethacrylate and lower than hexanediol diacrylate (HDDA) and 3-(acryloyloxy)-2-hydroxypropyl methacrylate (AHM).