Synthesis of six novel N,N-dialkyl derivatives of spermidine and effects on growth of the fungal plant pathogen Pyrenophora avenae.

Six novel N,N-dialkyl derivatives of spermidine were synthesised and examined for activity against the oat stripe pathogen Pyrenophora avenae. Two of these spermidine analogues, N,N-dimethyl-N1-(3-aminopropyl)-1,3-diaminopropane trihydrochloride (27) and N,N-dimethyl-N1-(3-aminopropyl)-1,4-diaminobutane trihydrochloride (28), reduced radial extension of P. avenae on plates when used at 2 mM, and caused more substantial reductions in fungal growth in liquid culture when used at 1 mM. Preliminary data suggest that neither compound affected polyamine biosynthesis, determined by following the incorporation of label from ornithine into polyamines and examining intracellular polyamine concentrations in fungal tissue.

Polyamine metabolism in the thermotolerant mesophilic fungus Aspergillus fumigatus.

Biomass production by Aspergillus fumigatus was greatest at 40-45 degrees C and was associated with an increase in concentration of the diamine putrescine and activity of its biosynthetic enzyme ornithine decarboxylase. Concentrations of the other amines, cadaverine, spermidine and spermine were considerably lower than putrescine concentration and did not change significantly over the temperature range 20-50 degrees C. This is surprising in view of the greatly increased flux of label from ornithine through to spermidine at 45 and 50 degrees C, indicating an increased formation of this triamine. It is suggested that there was increased formation of spermidine derivatives at these temperatures. Interestingly, there was greatly increased formation of the higher homologues of cadaverine, aminopropylcadaverine and N,N'-bis(3-aminopropyl)cadaverine, in A. fumigatus at 45 and 50 degrees C.

Synthesis and antifungal activity of two novel spermidine analogues.

Two spermidine analogues were synthesised and examined for antifungal activity. Both compounds used as 1 mM post-inoculation sprays reduced infection of barley seedlings by the powdery mildew fungus, Erysiphe graminis f.sp. hordei, infection of broad bean seedlings by the rust fungus, Uromyces viciae-fabae, and infection of apple seedlings by the powdery mildew fungus, Podosphaera leucotricha. Since these fungal pathogens cannot be cultured axenically, the effects of the two spermidine analogues on mycelial growth in vitro, as well as preliminary investigations on polyamine biosynthesis, were undertaken using the oat stripe pathogen, Pyrenophora avenae. Although neither compound affected radial growth of the fungus on plates, both analogues reduced fungal biomass in liquid culture substantially. The two spermidine analogues, used at a concentration of 1 mM, had no significant effect on the conversion of labelled ornithine into polyamines in P. avenae.

Preventive services in occupational health and safety in Europe: developments and trends in the 1990s.

This article outlines the legislative requirements for preventive services in health and safety in 13 European countries and considers the implementation and coverage of such services. The author identifies the predominant models of preventive services operating in the European Union, then assesses the influence of the E.U. Framework Directive 89/391 on the development and integration of preventive services and the role of workers in their organization and accountability. Significant differences exist in the extent and functions of preventive services in European countries, including differences in coverage between southern and northern European countries, different degrees to which employees in small enterprises and large enterprises are covered by preventive services, and overall differences in legislative approach.

Formation of cadaverine derivatives in Saccharomyces cerevisiae.

The higher homologues of cadaverine, aminopropylcadaverine (APC) and N,N-bis(3-aminopropyl)cadaverine (3APC) were formed by a wild-type strain of Saccharomyces cerevisiae, and by two mutant strains, spe 3-1 and spe 4-1, exhibiting point mutations in the genes for spermidine synthase and spermine synthase, respectively. This, together with the incomplete inhibition of APC and 3APC formation in the presence of inhibitors of S-adenosylmethionine decarboxylase and spermidine synthase, suggests that the cadaverine derivatives are formed partly by the operation of a different route. However, the yeast strains were unable to utilise [14C]aspartate and lysine to form APC and 3APC. Since the ornithine decarboxylase inhibitor alpha-difluoromethylornithine (DFMO) greatly reduced the formation of APC and 3APC, it is suggested that these compounds are formed preferentially in these yeast strains from cadaverine formed by ODC. APC and 3APC formation in the yeast strains was increased substantially following exposure to 37 degrees C for 2 h.

Pharmacokinetic study of (S)-(-)-2-(N-propyl-N-(2-thienylethyl)amino)-5-hydroxytetralin infusion in cynomolgus monkeys.

A pharmacokinetic study of the dopamine D2 receptor agonist (S)-(-)-2-(N-propyl-N-(2-thienylethyl)amino)-5-hydroxytetralin+ ++-HCl (N-0923) infused in female cynomolgus monkeys over a 4-h period was carried out at International Research and Development Corporation. The purpose of this study was to estimate the elimination half-life and elucidate the dose-clearance relationship in cynomolgus monkeys with a randomized three-way crossover intravenous (iv) infusion study design. Six female cynomolgus monkeys were dosed by iv infusion for 4 h with 0.1, 0.5, and 1.0 mg/kg/h. Plasma samples were drawn during the infusion and up to 4 h post infusion. The plasma concentrations were determined by a sensitive and specific HPLC assay with electrochemical detection after solid-phase extraction at the Department of Toxicology and Bioanalysis at the University Center for Pharmacy in Groningen, The Netherlands. The plasma data were best described by a two-compartment open model. Mean elimination half-lives of 36.8, 39.6, and 52.4 min and mean clearance values of 229 +/- 35, 202 +/- 85, and 191 +/- 36 mL/min/kg were obtained for doses of 0.1, 0.5, and 1.0 mg/kg/h, respectively. The steady-state volumes of distribution were estimated as 3.89 +/- 0.816, 3.53 +/- 1.62, and 4.70 +/- 3.67 L/kg for the same doses, respectively. There were no significant differences between any of the estimated pharmacokinetic parameters for any of the infusion doses. Clearance was not dose dependent and steady-state plasma concentration appeared directly proportional to dose, suggesting linear pharmacokinetics in this dose range for monkeys.

Polyamine metabolism in 'green-islands' on powdery mildew-infected barley leaves: possible interactions with senescence.

Polyamine metabolism, lipoxygenase and catalase activities and ethylene production were examined in green-islands induced to form on detached barley leaves infected with the powdery mildew fungus, Erysiphe graminis f. sp. hordei Marchal. Several-fold increases in free polyamines were detected in green-islands, which could not be accounted for by changes in polyamine biosynthetic and degradative enzymes: a small increase in ornithine decarboxylase (ODC) activity, greatly decreased arginine decarboxylase (ADC) activity, virtually unchanged activity of S-adenosylmethionine decarboxylase (AdoMetDC) and greatly increased polyamine oxidase (PAO) activity. Changes in conjugated forms of polyamines suggest that elevated free polyamine concentrations might result from reductions in this pool. Green-island tissues displayed a reduced activity of lipoxygenase, unchanged catalase activity and a greatly lowered rate of ethylene production. Chlorophyll concentration and rates of photosynthesis and dark respiration were slightly increased in these tissues. In senescing regions of infected leaves, there was a small increase in free putrescine and spermine and a decrease in spermidine concentration, while concentrations of conjugated polyamines were substantially reduced. This was accompanied by an overall decrease in ODC and ADC activities and an increased activity of both AdoMetDC and PAO. These regions exhibited lowered lipoxygenase activity, greatly enhanced catalase activity and reduced rates of ethylene production. In addition, senescing regions exhibited a substantial reduction in chlorophyll concentration and the rate of photosynthesis, although dark respiration was similar to control values. These results support the view that green-islands represent areas of the infected leaf where senescence is retarded, biosynthetic activity is retained and in which polyamines may play an important role. On the other hand, although polyamine concentrations were reduced in senescing areas, other changes occurring there suggest that some functional integrity is maintained in that tissue.

Shoot: root interrelationships in leeks infected with the rust, Puccinia allii Rud.: Growth and nutrient relations.

Growth and nutrient relations were examined in healthy leeks and in leeks inoculated with the rust, Puccinia allii, to give three different intensities of infection (i.e. 10, 20 and 30%). Experiments were conducted over an 8-week experimental period, although only data from 5 weeks after inoculation are shown. The dry weights of rust-infected plants were substantially reduced compared with controls over the entire experimental period. Although shoot: root (S: R) ratios were increased in rusted plants 2 weeks after inoculation, the trend was reversed thereafter and for the remainder of the experiment S:R ratio was reduced in comparison with healthy controls. The contents of nitrogen, phosphate, potassium and calcium were reduced in rusted plants compared to controls. On the other hand, with few exceptions, the concentrations and specific absorption rates of these minerals increased in rusted plants compared with healthy controls. The ability of infected plants to maintain a functional S:R equilibrium with respect to nutrient uptake was examined using an analysis based on comparing changes in incremental plant dry weight with incremental nutrient weight. Calculated values of functional equilibrium for control and rusted plants showed that rust infection altered functional equilibrium with respect to uptake of the four nutrients. The possible mechanisms underlying these changes in physiology and the analysis of such changes are discussed.

THE EFFECTS OF A POLYAMINE BIOSYNTHESIS INHIBITOR ON INFECTION OF VICIA FABA L. BY THE RUST FUNGUS, UROMYCES VICIAE-FABAE (PERS.) SCHROET.

The effects of the polyamine biosynthesis inhibitor, difluoromethylomithine (DFMO), on rust infection of the broad bean have been examined. DFMO was sprayed onto leaves at 0.025, 0.1 and 0.4 mM before and after inoculation. DFMO was also applied to leaf halves in order to examine the possible translocation of the inhibitor to untreated leaf halves (systemic treatment). DFMO gave good control of rust infection, irrespective of the treatment. DFMO applied after inoculation was more effective than a pre-inoculatory treatment when used in non-systemic tests. When used as a systemic treatment on leaf halves, pre-inoculatory application of DFMO was more effective. DFMO did not affect plant growth or endogenous concentrations of poly amines. The possible use of DFMO in the control of a range of plant diseases is discussed.