Blends of Poly(lactic acid) with Thermoplastic Acetylated Starch

Blends of poly(lactic acid)(PLA) and thermoplastic acetylated starch(ATPS) were prepared by means of the melt mixing method. The results show that PLA and ATPS were partially miscible, which was confirmed with the measurement of T-g by dynamic mechanical analysis(DMA) and differrential scanning calorimetry(DSC). The mechanical and thermal properties of the blends were improved. With increasing the ATPs content, the elongation at break and impact strength were increased. The elongation at break increased from 5% of neat PLA to 25% of the blend PLA/ATPS40. It was found that the cold crystallization behavior of PLA changed evidently by addition of ATPS. The cold crystallization temperature(T-cc) of each of PLA/ATPS blends was found to shift to a lower temperature and the width of exothermic peak became narrow compared with that of neat PLA.

Preparation and in vitro antioxidant activity of kappa-carrageenan oligosaccharides and their oversulfated, acetylated, and phosphorylated derivatives

In order to study the relationship between chemical structure and properties of modified carrageenans versus antioxidant activity in vitro, K-carrageenan oligosaccharides were prepared through mild hydrochloric acid hydrolysis of the polysaccharide, and these were used as starting materials for the partial synthesis of their oversulfated, acetylated, and phosphorylated derivatives. The structure and substitution pattern of the oligosaccharides and their derivatives were Studied using FTIR and C-13 NMR spectroscopy, and their in vitro antioxidant activities were investigated. Certain derivatives of the carrageenan oligosaccharides exhibited higher antioxidant activity than the polysaccharides and oligosaccharides in certain antioxidant systems. The oversulfated and acetylated derivatives, which scavenge superoxide radicals, the phosphorylated and low-DS acetylated derivatives, which scavenge hydroxyl radicals, and the phosphorylated derivatives, which scavenge DPPH radicals, all exhibited significant antioxidant activities it, the systems examined. The effect of the molecular weight of the carrageenan on antioxidant activities, however, is not obvious from these studies. (c) 2005 Elsevier Ltd. All rights reserved.

Synthesized oversulphated, acetylated and benzoylated derivatives of fucoidan extracted from Laminaria japonica and their potential antioxidant activity in vitro

Three sulphated polysaccharide derivatives (oversulphated, acetylated and benzoylated fucoidan) were successfully synthesized, and their antioxidant activities were investigated employing various established in vitro systems. A novel catalyst N-bromosuccinimide (NBS) was used in acetylation and benzoylation reaction, and the degree of acetylation was evaluated using IR and NMR spectra. Both fucoidan derivatives possessed considerable antioxidant activity, and had stronger antioxidant ability than fucoidan in certain tests. The benzoylated fucoidan showed strongest superoxide and hydroxyl radical scavenging activity, however, the acetylated fucoidan exhibited strongest activity on scavenging DPPH radical and reducing power. Available data obtained with in vitro models suggested that substituted groups of fucoidan played an important role on antioxidant activity. The mechanism on the antioxidant activity of sulphonyl, acetyl and benzoyl group is different. (C) 2008 Elsevier Ltd. All rights reserved.

In vitro antioxidant activities of acetylated, phosphorylated and benzoylated derivatives of porphyran extracted from Porphyra haitanensis

Porphyran extracted from red algae Porphyra haitanensis is a sulfated polysaccharide, which possesses excellent antioxidant activities. In this study, we prepared the acetylated, phosphorylated and benzoylated derivatives of porphyran. And then the antioxidant activities of all the samples were investigated including scavenging effects of superoxide and hydroxyl radicals and reducing power. The results of chemical analysis and FT-IR spectrum showed the modifications of porphyran were successful. And in addition, we found that certain derivative exhibited stronger antioxidant activity than raw material. And the mechanism of the structure-function relationship of these derivatives needs to be attended to. (C) 2009 Elsevier Ltd. All rights reserved.

In vitro antioxidant activity of acetylated and benzoylated derivatives of polysaccharide extracted from Ulva pertusa (Chlorophyta)

The antioxidant activity of natural ulvan and its derivatives (acetylated and benzoylated ulvans) in vitro was determined, including scavenging activity against superoxide and hydroxyl radicals, reducing power, and chelating ability. Obvious differences in antioxidant activity between natural ulvan and its derivatives were observed, moreover, the antioxidant activity of acetylated and benzoylated ulvans was stronger than that of natural ulvan. (C) 2006 Elsevier Ltd. All rights reserved.

S6K1 is acetylated at lysine 516 in response to growth factor stimulation

The 70kDa ribosomal protein S6 kinase 1 (S6K1) plays important roles in the regulation of protein synthesis, cell growth and metabolism. S6K1 is activated by the phosphorylation of multiple serine and threonine residues in response to stimulation by a variety of growth factors and cytokines. In addition to phosphorylation, we have recently shown that S6K1 is also targeted by lysine acetylation. Here, using tandem mass spectrometry we have mapped acetylation of S6K1 to lysine 516, a site close to the C-terminus of the kinase that is highly conserved amongst vertebrate S6K1 orthologues. Using acetyl-specific K516 antibodies, we show that acetylation of endogenous S6K1 at this site is potently induced upon growth factor stimulation. Although S6K1 acetylation and phosphorylation are both induced by growth factor stimulation, these events appear to be functionally independent. Indeed, experiments using inhibitors of S6K1 activation and exposure of cells to various stresses indicate that S6K1 acetylation can occur in the absence of phosphorylation and vice versa. We propose that K516 acetylation may serve to modulate important kinase-independent functions of S6K1 in response to growth factor signalling.

New tetra-acetylated oligosaccharide diterpene from Cupania vernalis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Acetylated DNA-damaging clerodane diterpenes from Casearia sylvestris

In addition to the known diterpene casearin G (1), two new clerodane diterpene casearins type, casearin S (2) and casearin T (3), were isolated from an acetylated bioactive CH2Cl2/MeOH extract from leaves of Casealia sylvestris. The diterpenes 1-3 exhibited moderate but selective activity towards the DNA-repair deficient yeast Saccharomyces cerevisiae mutants RAD 52YK and RS 321. The structures of 1-3 were established on the basis of NMR spectroscopic experiments (C) 1998 Elsevier B.V. Ltd. All rights reserved.

THE ISOLATION AND IDENTIFICATION OF O-ACETYLATED SIALIC ACIDS ON HUMAN CELLS (NEURAMINIC ACIDS, PAPER CHROMATOGRAPHY, HUMAN MALIGNANCY, BIOSYNTHETIC LABELING)

Unlike most carbohydrates, sialic acids have a restricted distribution in nature, being present in higher animals and in certain bacteriae. Unfortunately, most studies have not taken into account the fact that the parent sialic acid molecules, N-acetyl(or N-glycolyl)-neuraminic acid can be O-substituted at the 4, 7, 8 and 9 positions, generating many compounds and isomers. The approach and results of this research study demonstrates that proportions of non-, mono-, di-, and tri-O-acetylated sialic acids can be identified and quantitated on normal and malignant human cells. This was accomplished using a paper chromatographic technique to isolate and resolve individual species of non and O-substituted sialic acids. The chemical nature of these O-substituents, as an acetyl ester, was determined on the basis of chemical degradation, enzymatic and fast atom bombardment-mass spectrometry analysis.^ The working hypothesis of this study, that O-acetylated sialic acids are expressed in a restricted manner on normal and malignant cells, was confirmed using the above experimental approach; which identified mono-, di-, and tri-O-acetylated sialic acids on a variety of normal and malignant human cells. These O-acetylated sialic acids were expressed in restricted manner on subpopulations and subcellular fractions of PHL melanoma cells. Aberrant expression of O-acetylated sialic acids was associated with adenocarcinoma of the colon, leading to a nearly complete loss of di- and tri-O-acetylated sialic acids.^ Thus, the ability to isolate and identify biosynthetically radiolabeled O-acetylated sialic acids offers an efficient method of monitoring the expression of O-acetylated sialic acids in biochemical and cellular interactions. Furthermore, the ability to identify abnormal ratios of O-acetylated sialic acids in the human colon, represents a possible diagnostic tool to evaluate and identify patients who may be genetically or culturally predisposed to the development of adenocarcinoma of the colon. ^

Organization of Highly Acetylated Chromatin around Sites of Heterogeneous Nuclear RNA Accumulation

Histones found within transcriptionally competent and active regions of the genome are highly acetylated. Moreover, these highly acetylated histones have very short half-lives. Thus, both histone acetyltransferases and histone deacetylases must enrich within or near these euchromatic regions of the interphase chromatids. Using an antibody specific for highly acetylated histone H3, we have investigated the organization of transcriptionally active and competent chromatin as well as nuclear histone acetyltransferase and deacetylase activities. We observe an exclusion of highly acetylated chromatin around the periphery of the nucleus and an enrichment near interchromatin granule clusters (IGCs). The highly acetylated chromatin is found in foci that may reflect the organization of highly acetylated chromatin into “chromonema” fibers. Transmission electron microscopy of Indian muntjac fibroblast cell nuclei indicates that the chromatin associated with the periphery of IGCs remains relatively condensed, most commonly found in domains containing chromatin folded beyond 30 nm. Using electron spectroscopic imaging, we demonstrate that IGCs are clusters of ribonucleoprotein particles. The individual granules comprise RNA-rich fibrils or globular regions that fold into individual granules. Quantitative analysis of individual granules indicates that they contain variable amounts of RNA estimated between 1.5 and >10 kb. We propose that interchromatin granules are heterogeneous nuclear RNA-containing particles, some of which may be pre-mRNA generated by nearby transcribed chromatin. An intermediary zone between the IGC and surrounding chromatin is described that contains factors with the potential to provide specificity to the localization of sequences near IGCs.

Comparison of the Ability of Partially N-Acetylated Chitosans and Chitooligosaccharides to Elicit Resistance Reactions in Wheat Leaves1

Chitin, a linear polysaccharide composed of (1→4)-linked 2-acetamido-2-deoxy-β-d-glucopyranose (GlcNAc) residues, and chitosan, the fully or partially N-acetylated, water-soluble derivative of chitin composed of (1→4)-linked GlcNAc and 2-amino-2-deoxy-β-d-glucopyranose (GlcN), have been proposed as elicitors of defense reactions in higher plants. We tested and compared the ability of purified (1→4)-linked oligomers of GlcNAc (tetramer to decamer) and of GlcN (pentamer and heptamer) and partially N-acetylated chitosans with degrees of acetylation (DA) of 1%, 15%, 35%, 49%, and 60% and average degrees of polymerization between 540 and 1100 to elicit phenylalanine ammonia-lyase (PAL) and peroxidase (POD) activities, lignin deposition, and microscopically and macroscopically visible necroses when injected into the intercellular spaces of healthy, nonwounded wheat (Triticum aestivum L.) leaves. Purified oligomers of (1→4)-linked GlcN were not active as elicitors, whereas purified oligomers of (1→4)-linked GlcNAc with a degree of polymerization ≥ 7 strongly elicited POD activities but not PAL activities. Partially N-acetylated, polymeric chitosans elicited both PAL and POD activities, and maximum elicitation was observed with chitosans of intermediate DAs. All chitosans but not the chitin oligomers induced the deposition of lignin, the appearance of necrotic cells exhibiting yellow autofluorescence under ultraviolet light, and macroscopically visible necroses; those with intermediate DAs were most active. These results suggest that different mechanisms are involved in the elicitation of POD activities by GlcNAc oligomers, and of PAL and POD activities by partially N-acetylated chitosan polymers and that both enzymes have to be activated for lignin biosynthesis and ensuing necrosis to occur.

Disaccharide uptake and priming in animal cells: inhibition of sialyl Lewis X by acetylated Gal beta 1-->4GlcNAc beta-O-naphthalenemethanol.

Inhibitors of glycosylation provide a tool for studying the biology of glycoconjugates. One class of inhibitors consists of glycosides that block glycoconjugate synthesis by acting as primers of free oligosaccharide chains. A typical primer contains one sugar linked to a hydrophobic aglycone. In this report, we describe a way to use disaccharides as primers. Chinese hamster ovary cells readily take up glycosides containing a pentose linked to naphthol, but they take up hexosides less efficiently and disaccharides not at all. Linking phenanthrol to a hexose improves its uptake dramatically but has no effect on disaccharides. To circumvent this problem, analogs of Xyl beta 1-->6Gal beta-O-2-naphthol were tested as primers of glycosaminoglycan chains. The unmodified disaccharide did not prime, but methylated derivatives had activity in the order Xyl beta 1-->6Gal(Me)3-beta-O-2-naphthol > Xyl beta 1-->6Gal (Me)2 beta-O-2-naphthol >> Xyl beta 1-->6Gal(Me)beta-O-2-naphthol. Acetylated Xyl beta 1-->6Gal beta-O-2-naphthol also primed glycosaminoglycans efficiently, suggesting that the terminal xylose residue was exposed by removing the acetyl groups. The general utility of using acetyl groups to create disaccharide primers was shown by the priming of oligosaccharides on peracetylated Gal beta 1-->4GlcNAc beta-O-naphthalenemethanol. This disaccharide inhibited sialyl Lewis X expression on HL-60 cells.

Isolation of microvascular endothelial cells from cadaveric corneal limbus

Limbal microvascular endothelial cells (L-MVEC) contribute to formation of the corneal-limbal stem cell niche and to neovascularization of diseased and injuries corneas. Nevertheless, despite these important roles in corneal health and disease, few attempts have been made to isolate L-MVEC with the view to studying their biology in vitro. We therefore explored the feasibility of generating primary cultures of L-MVEC from cadaveric human tissue. We commenced our study by evaluating growth conditions (MesenCult-XF system) that have been previously found to be associated with expression of the endothelial cell surface marker thrombomodulin/CD141, in crude cultures established from collagenase-digests of limbal stroma. The potential presence of L-MVEC in these cultures was examined by flow cytometry using a more specific marker for vascular endothelial cells, CD31/PECAM-1. These studies demonstrated that the presence of CD141 in crude cultures established using the MesenCult-XF system is unrelated to L-MVEC. Thus we subsequently explored the use of magnetic assisted cell sorting (MACS) for CD31 as a tool for generating cultures of L-MVEC, in conjunction with more traditional endothelial cell growth conditions. These conditions consisted of gelatin-coated tissue culture plastic and MCDB-131 medium supplemented with fetal bovine serum (10% v/v), D-glucose (10 mg/mL), epidermal growth factor (10 ng/mL), heparin (50 μg/mL), hydrocortisone (1 μg/mL) and basic fibroblast growth factor (10 ng/mL). Our studies revealed that use of endothelial growth conditions are insufficient to generate significant numbers of L-MVEC in primary cultures established from cadaveric corneal stroma. Nevertheless, through use of positive-MACS selection for CD31 we were able to routinely observe L-MVEC in cultures derived from collagenase-digests of limbal stroma. The presence of L-MVEC in these cultures was confirmed by immunostaining for von Willebrand factor (vWF) and by ingestion of acetylated low-density lipoprotein. Moreover, the vWF+ cells formed aligned cell-to-cell ‘trains’ when grown on Geltrex™. The purity of L-MVEC cultures was found to be unrelated to tissue donor age (32 to 80 years) or duration in eye bank corneal preservation medium prior to use (3 to 10 days in Optisol) (using multiple regression test). Optimal purity of L-MVEC cultures was achieved through use of two rounds of positive-MACS selection for CD31 (mean ± s.e.m, 65.0 ± 20.8%; p<0.05). We propose that human L-MVEC cultures generated through these techniques, in conjunction with other cell types, will provide a useful tool for exploring the mechanisms of blood vessel cell growth in vitro.

Effects of oral calcium sensitizers on experimental heart failure

Suun kautta annosteltava kalsiumherkistäjä parantaa sydämen vajaatoimintaan liittyvää pumppausvajetta kokeellisissa sydämen vajaatoimintamalleissa Huolimatta viime vuosikymmenien lääketieteellisestä kehityksestä krooninen sydämen vajaatoiminta on silti edelleen vakava, elämänlaatua voimakkaasti rajoittava sairaus. Kalsiumherkistäjät ovat uusi, sydämen pumppausvoimaa lisäävä lääkeryhmä. Levosimendaani, kotimaista alkuperää oleva kalsiumherkistäjä, on kliinisessä käytössä akuutin vajaatoiminnan hoitoon suonensisäisesti ja lyhytaikaisesti annosteltavana valmisteena. Levosimendaanilla on aktiivinen metaboliitti, OR-1896, jonka oletetaan olevan vuorokauden mittaisen levosimendaani-infuusion jälkeen havaittujen useita päiviä kestävien hyödyllisisten vaikutuksisten takana. Levosimendaanin kroonisen, suun kautta tapahtuvan annostelun vaikutuksista tieto on vähäisempää, mutta sillä näyttää olevan positiivisia vaikutuksia potilaiden raportoimana. FM Marjut Louhelainen on selvittänyt väitöskirjassaan suun kautta annosteltavan levosimendaanin ja sen pitkäkestoisen aktiivisen metaboliitin vaikutuksia kroonisen vajaatoiminnan hoidossa käyttämällä sekä hypertensiivisen sydäntaudin että 2 tyypin diabeteksen komplisoimaan sydäninfarktin kokeellisia malleja. Tutkimuksessa selvitettiin lisäksi vajaatoimintaan johtavia molekyylitason tapahtumia sydänlihaksessa. Tutkimuksessa osoitettiin, että krooninen suun kautta annosteltu hoito sekä kalsiumherkistäjä levosimendaanilla että sen aktiivisella metaboliitilla estää hypertensiiviseen sydämen vajaatoiminnan aikaasaamaa sydämen uudelleenmuovaantumista ja siihen liittyvää kuolleisuutta. Nämä vaikutukset välittyivät vähentyneen sydänlihassoluhypertrofian, solukuolleisuuden ja neurohumaraalisen aktivaation kautta. Levosimendaanin ja OR-1896:n osoitettiin myös parantavan sydämen pumppausfunktiota tyyppi 2 diabeteksen komplisoimassa sydäninfarktissa. Ei-diabeettiseen tilanteeseen verrattuna diabetekseen liittyvä infarktin jälkeinen vajaatoiminnan kehitys oli yhteydessä lisääntyneeseen tulehdukseen, fibroosiin, solukuolemaan, neurohumoraaliseen aktivaatioon ja ennenaikaiseen kudoksen vanhenemiseen. Sekä levosimendaani, että OR-1869 vähensivät tulehduksen, fibroosin ja solukuoleman merkkejä ja vaimensi neurohumoraalista aktivaatiota. OR-1896 myös vähensi solujen vanhenemiseen liittyvien merkkiaineiden ilmentymistä. Väitöskirjassa todettiin, että suun kautta annosteltuna sekä levosimendaani, että sen aktiivinen metaboliitti OR-1896, omaavat terapeuttista potentiaalia sekä hypertensiivisen sydäntaudin hoitoon että sydäninfarktin jälkeisen vajaatoiminnan estoon. FM Marjut Louhelaisen farmakologian alaan kuuluva väitöskirja Effects of oral calcium sensitizers on experimental heart failure tarkastetaan Helsingin yliopiston Lääketieteellisessä tiedekunnassa perjantaina 29.01.2010 klo 12 (Biomedicum Helsinki, luentosali 2, Haartmaninkatu 8, Helsinki). Vastaväittäjänä toimii professori Raimo Tuominen, Helsingin yliopiston Farmasian tiedekunnasta ja kustoksena professori Eero Mervaala Helsingin yliopiston Lääketieteellisestä tiedekunnasta.