Imperial Chemical Industries

About: Imperial Chemical Industries is a based out in . It is known for research contribution in the topics: Alkyl & Catalysis. The organization has 8189 authors who have published 7809 publications receiving 190252 citations. The organization is also known as: Imperial Chemical Industries Ltd.

The inhibition of nucleic acid synthesis by mycophenolic acid

Abstract: 1 Mycophenolic acid, an antibiotic of some antiquity that more recently has been found to have marked activity against a range of tumours in mice and rats, strongly inhibits DNA synthesis in the L strain of fibroblasts in vitro 2 The extent of the inhibition of DNA synthesis is markedly increased by preincubation of the cells with mycophenolic acid before the addition of [(14)C]thymidine 3 The inhibition of DNA synthesis by mycophenolic acid in L cells in vitro is reversed by guanine in a non-competitive manner, but not by hypoxanthine, xanthine or adenine 4 The reversal of inhibition by guanine can be suppressed by hypoxanthine, 6-mercaptopurine and adenine 5 Mycophenolic acid does not inhibit the incorporation of [(14)C]thymidine into DNA in suspensions of Landschutz and Yoshida ascites cells in vitro 6 Mycophenolic acid inhibits the conversion of [(14)C]hypoxanthine into cold-acid-soluble and -insoluble guanine nucleotides in Landschutz and Yoshida ascites cells and also in L cells in vitro There is some increase in the radioactivity of the adenine fraction in the presence of the antibiotic 7 Mycophenolic acid inhibits the conversion of [(14)C]hypoxanthine into xanthine and guanine fractions in a cell-free system from Landschutz cells capable of converting hypoxanthine into IMP, XMP and GMP 8 Preparations of IMP dehydrogenase from Landschutz ascites cells, calf thymus and LS cells are strongly inhibited by mycophenolic acid The inhibition showed mixed type kinetics with K(i) values of between 303x10(-8) and 45x10(-8)m 9 Evidence was also obtained for a partial, possibly indirect, inhibition by mycophenolic acid of an early stage of biosynthesis of purine nucleotides as indicated by a decrease in the accumulation of formylglycine amide ribonucleotide induced by the antibiotic azaserine in suspensions of Landschutz and Yoshida ascites cells and L cells in vitro

Pig Ear Skin as an In‐vitro Model for Human Skin Permeability

Abstract: Pig skin has been shown to have similar histological and physiological properties to human skin and has been suggested as a good model for human skin permeability. In this series of experiments, the in-vitro permeability of pig ear skin was compared with human (abdominal) skin and rat (dorsal) skin using both hydrophilic (water, mannitol, paraquat) and lipophilic (aldrin, carbaryl, fluazifop-butyl) penetrants. Pig skin was found to have a closer permeability character than rat skin to human skin, particularly for lipophilic penetrants. Electrical conductivity measurements across pig skin membranes showed that skin conductivity could be a useful method for assessing the integrity of membranes, particularly when used in conjunction with water permeability assessments.

Crystal Structure of Polyvinyl Alcohol

Abstract: IT has often been said (by me1 as well as by others) that the molecular repeat distance (from X-ray diffraction photographs) of polyvinyl alcohol—2·52 A.2—indicates not only that the chain has a simple plane zigzag configuration, but also that all the hydroxyl groups (in the section of a molecule in one crystallite) lie on the same side of the zigzag plane. This is not necessarily true ; so far as X-ray diffraction is concerned, the observed repeat distance is equally compatible with a molecular structure in which hydroxyl groups are randomly placed in left-and right-hand positions. This possibility was not considered until recently ; it was assumed that the high degree of crystallinity of polyvinyl alcohol implied regularity of molecular structure. Recently, however, it has been found3 that interpolymers of ethylene and vinyl alcohol are crystalline ; thus hydroxyl groups may replace hydrogen atoms at random on a carbon chain without destroying crystallinity ; the high crystallinity of polyvinyl alcohol cannot, therefore, be regarded as evidence against the idea of stereochemical irregularity in this molecule.