The common precursor to all tetrapyrroles is 5-aminolevulinic acid (ALA), and in Rhodobacter sphaeroides its formation occurs via the Shemin pathway. ALA synthase activity is encoded by two differentially regulated genes in R. sphaeroides 2.4.1: hemA and hemT. In our investigations of hemA regulation, we applied transposon mutagenesis under aerobic conditions, followed by a selection that ident...

The Bacillus subtilis hemAXCDBL operon encodes enzymes for the biosynthesis of uroporphyrinogen III from glutamyl-tRNA. The function of the hemX gene product was studied in this work. The deduced amino acid sequence suggests HemX to be an integral 32 kDa membrane protein. This was confirmed by experiments using Escherichia coli minicells and hemX-phoA gene fusions. Deletion of the hemX gene fro...

In the cyanobacterium Synechocystis sp. PCC 6803 and in the enterobacterium Escherichia coli delta-amino-levulinic acid (ALA) is formed from glutamyl-tRNA by the sequential action of two enzymes, glutamyl-tRNA reductase (GluTR) and glutamate-1-semialdehyde aminotransferase. E. coli has two GluTR proteins with sizes of 45 kDa (GluTR45) and 85 kDa (GluTR85) (Jahn, D., Michelsen, U., and Söll, D. ...

The purpose of this study was to evaluate the cytotoxicity of acrylic and methacrylic acid (AA and MA), propanoic acid and isobutylic acid (PRA and IBA) which were the corresponding saturated carboxylic acids, 2-hydroxylethyl methacrylate and acrylate (HEMA and HEA), and hydroquinone (HQ). The growth of the fibroblast when exposed to AA decreased with increase of the acid, and was less than whe...

5-aminolevulinic acid (ALA) is a precursor in the biosynthesis of tetrapyrroles including chlorophylls and heme. The formation of ALA involves two enzymatic steps which take place in the chloroplast in plants. The first enzyme, glutamyl-tRNA reductase, and the second enzyme, glutamate-1-semialdehyde-2,1-aminomutase, are encoded by the nuclear HEMA and GSA genes, respectively. To assess the sign...

Self-exploding microparticles show potential for advanced delivery of certain therapeutics. This study evaluates (1) whether degrading biodegradable dextran hydroxyethyl methacrylate (dex-HEMA) microgels can be coated by a lipid membrane and (2) whether the surrounding membrane can be ruptured by the increasing swelling pressure of the degrading microgel. We found that adsorption of charged lip...

Degrading hydroxyethylmethacrylate-grafted dextran (dex-HEMA) hydrogels generate a relatively sudden increase in osmotic pressure upon degradation into dextran solutions. This phenomenon is currently being examined as a possible means of developing a pulsatile drug-delivery system. Here a mathematical model based on scaling concepts is presented to describe this sudden increase in swelling pres...

All ancient nations hinged their beliefs about hema (blood) on their religious dogmas as related to mythology or the origins of religion. The Hellenes (Greeks) especially have always known hema as the well-known red fluid of the human body. Greek scientific considerations about blood date from Homeric times. The ancient Greeks considered hema as synonymous with life. In Greek myths and historic...

Chitosan based membranes to be applied on wound healing as topical drug delivery systems were developed by graft copolymerization of acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) onto chitosan using cerium ammonium nitrate as chemical initiator. Evidence for graft copolymerization of the vinyl monomers onto chitosan was obtained by FTIR and DMTA. Swelling degree, cytotoxicity, thromb...

The effect of momentary pretreatment by 35% HEMA solution on the adaptation between dentin and resin material was investigated by measuring wall-to-wall polymerization contraction in a cylindrical dentin cavity. Five marketed bonding agents tested in this study exhibited improved marginal seal when the dentin cavity wall was pretreated by 35% HEMA for a few seconds with the exception of Pyrofi1...