PubMed · 5773038
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B F Taylor, M Currie, D S Hoare. 1969. Aromatic ring cleavage by a Thiobacillus.. https://doi.org/10.1128/jb.97.2.959-960.1969
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We established an effective monoepoxide-generating system by combining cytochrome-c (Cyt-c) with a hydrogen peroxide (H2O2)-generating system comprising hypoxanthine (HX), xanthine oxidase (XO) and superoxide dismutase (SOD; HX-XO-SOD-Cyt-c system). Using this and the H2O2-Cyt-c system, we proved that monoepoxide production from linoleic acid was due to hydroxy radical formation by the reaction of Cyt-c with H2O2 and not to the formation of other active oxygen species.
Retinoids stimulate tissue-type plasminogen-activator (t-PA) gene expression in human endothelial cells, and are likely to do so by binding to one or more nuclear retinoid receptors. The present study was initiated to identify the retinoid receptor(s) involved in this process. Expression and regulation of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) were analyzed by Northern-blot analysis of total or poly(A)-rich RNA prepared from cultured human umbilical vein endothelial cells (HUVEC). Prior to any exposure to retinoids, HUVEC express two transcripts for RAR-alpha (3.6 kb and 2.8 kb), and low levels of transcripts for RAR-beta (3.4 kb and 3.2 kb) and RAR-gamma (3.3 kb and 3.1 kb). Two RXR subtypes were identified, RXR-alpha (4.8 kb) and, at a much lower concentration, RXR-beta (2.4 kb); no evidence for the presence of RXR-gamma was found. Furthermore, HUVEC express cellular retinol-binding protein I (CRBP-I) and cellular retinoic-acid-binding protein I (CRABP-I) mRNA. Exposure of HUVEC to 1 microM retinoic acid or the retinobenzoic acid, Ch55, led to the induction of the two RAR-beta mRNAs, RXR-alpha mRNA and CRBP-I mRNA, whereas the expression of the other receptor and CRABP-I transcripts did not change appreciably. Using retinoid analogues that bind preferentially to one of the RAR or RXR subtypes, we found evidence that RAR-alpha is involved in the retinoid-induced t-PA expression in HUVEC. This conclusion was strengthened by experiments in which blocking of RAR-alpha with a specific RAR-alpha antagonist, Ro 41-5253, was demonstrated to suppress the induction of t-PA by retinoids.
PURPOSE: This study describes the development of a microcalorimetric flow cell which allows powder surface energetics to be probed my means of measuring their interaction with water vapour. METHODS: A flow cell has been constructed and tested in an isothermal microcalorimeter to assess the interaction between water vapour and powder surfaces. The cell was constructed to mix two separate air streams (0% and 100% relative humidity respectively) to create any humidity at a standard flow rate. The powder sample was equilibrated in dry air and then exposed to sequential increments in humidity. RESULTS: Adsorption isotherms were constructed from the cumulative heat as a function of humidity. It was possible to differentiate between different samples of alpha-lactose monohydrate (which appeared identical by contact angle determination). It was also possible to measure adsorption to two different alkyl p-hydroxybenzoates which were hydrophobic and of low surface area. CONCLUSIONS: This technique offers a very sensitive and versatile method of obtaining a reliable indication of powder surface energetics and as such is a major advance in the field.