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Abstract: Objective: The concept of clopidogrel resistance is frequently evoked in the cardiac literature. The variability of antiplatelet response in patients with intermittent claudication has not been investigated. The aim of this study was to describe the effect of the addition of clopidogrel to aspirin using ex vivo measures of platelet activation in patients with life-style limiting intermittent claudication. Design of study: Data from randomised controlled trial. Materials: Data from 67 patients with intermittent claudication taking part in a randomised controlled trial and who received clopidogrel in addition to aspirin was analysed. Methods: Platelet activation was measured using whole-blood flow cytometric measurement of ADP-stimulated fibrinogen binding at baseline and 12h after administration of a loading dose of 300mg clopidogrel. Patients continued to receive 75mg clopidogrel daily for 30 days and platelet activation was again measured at day 30. Compliance with treatment was assessed by counting returned tablets. Results: Six patients were excluded from analysis because of incomplete compliance with treatment. Six of the sixty-one patients (9.8%) showed no reduction in platelet activation 12h after administration of the loading dose of clopidogrel. At 30 days these six patients still showed no response to clopidogrel. Amongst the remaining 55 patients, the mean reduction in fibrinogen binding after clopidogrel administration was 51.5% (95% CI: 43.8–59.2). Amongst responders there was a wide variability in reduction of fibrinogen binding in response to clopidogrel (range 8.11–97.7%). Four of these patients (6.6%) showed a reduction of more than 95% in fibrinogen binding. Conclusions: Patients with intermittent claudication show a wide variability in their response to clopidogrel. While a small proportion of these patients shows no response at all, another small group appears to respond excessively to clopidogrel. Clinical studies are required to identify whether hyper-responders are at increased risk of bleeding complications and whether hyporesponders are at a higher risk of thrombotic events. [Copyright &y& Elsevier]

Abstract: Background: Platelet and endothelial activation has been shown to be increased in patients with intermittent claudication (IC). Recent studies have suggested that exercise may induce further platelet activation. The aims of this study were to investigate the effect of exercising to maximum walking distance on platelet and endothelial function in patients with intermittent claudication who were receiving statin and aspirin therapy compared with age matched healthy controls. Methods: Platelet aggregation through COX-mediated and thrombin receptor activator peptide (TRAP)-stimulated GPIIb/IIIa pathways was measured by the Ultegra point of care system in 20 patients with IC on aspirin and 20 healthy volunteers before, immediately and 1h after exercising to treadmill maximal walking distance (MWD). Soluble P-selectin, vWF and sICAM were measured using an enzyme linked immuno-sorbent assay technique. Results: Baseline platelet aggregation was significantly reduced in patients with IC compared to volunteers (p<0.05). In patients, exercising to MWD significantly reduced platelet aggregation (COX, median −5% [range −24 to 13%]; p=0.02; GPIIIa/IIb, median −13% [range −72 to 33%]; p=0.02) immediately post-exercise which returned to baseline values at 1h. There was no change in the healthy volunteers following the same median duration of exercise. Baseline sP-selectin levels were higher in the patients with IC compared to the healthy volunteers [Median values (interquartile range), 42.72 (33.28–54.24) versus 29.16 (24.40–34.10), p=0.0003] but there were no differences in vWF levels. Both sP-selectin and vWF levels increased significantly in the control and patient group following exercise (p<0.005). sICAM were higher at baseline in the patients with IC but were unchanged following exercise [Median values (interquartile range),560.9 (405.5–739.4) versus 467.0 (325.7–643.4), p<0.05]. Conclusion: This study is the first to show that platelet aggregation is reduced immediately following treadmill exercise to maximum walking distance in patients with IC despite a rise in sP-selectin and vWF, suggesting endothelial activation. The inhibition of platelet aggregation after exercise in subjects on antiplatelet and statin therapy suggests that exercise is unlikely to exacerbate platelet thrombus formation in patients with IC. [Copyright &y& Elsevier]

Inclusion of Alternaria alternata conidia in a spray formulation affected the distribution pattern on the target. The dry weight of Amaranthus retroflexus plants was reduced by more than 83% when A. alternata conidia (107 ml[sup -1]) were applied at 200 L ha[sup -1] or greater and when given a 24 h dew period. At low application volumes (25 or 50 L ha[sup -1]) plant dry weight was reduced by only 29 or 54%. After 7–8 h dew period, conidial germination on the leaf surface was 11–19%. This increased to 62–91% after 24 h dew period. Counts of conidia on leaves indicated that up to 86% of the conidia sprayed were not retained on the target plant, or did not reach it. This is reflected in lesion numbers per unit area being only 3–5% of the calculated theoretical numbers. The results cast doubt on the suitability of A. alternata as a microbial herbicide for the control of Am. retroflexus. [ABSTRACT FROM AUTHOR]

Colletotrichum truncatum conidia produced from a one week-old culture in a liquid semi-defined medium with a C:N ratio of 5:1 were more tolerant of desiccation than those harvested from two or three week-old cultures. Conidia washed with 20% (w/v) sucrose germinated better than unwashed conidia or those washed in 10% (w/v) sucrose, 10 and 20% (w/v) glucose or fructose, 0.1% (w/v) soluble starch, 0.9% (w/v) NaCl or deionized water. Washing with sucrose (20% w/v) also resulted in significantly longer germ tubes than those produced by unwashed conidia or conidia washed with deionized water or NaCl (0.9% w/v). Conidia washed twice in sucrose showed greater desiccation tolerance during storage at 15% relative humidity (RH) and 15°C than at 30% RH and 15 or 25°C or at 15% RH and 25, 5 or -10°C. [ABSTRACT FROM AUTHOR]

This paper addresses the hypothesis that the spray application system used will affect the retention of spray deposits of microbial herbicides on different plant structures. There was greater spray retention on the hypocotyl of 4 to 6-true leaf Amaranthus retroflexus plants (20-31%) sprayed with an aerosol-producing laboratory sprayer than with a hydraulic nozzle (3-5%). Spray deposition and retention from the hydraulic nozzle was increased by 28-42% when the nozzle was used horizontally. Spray droplets generally contained the expected conidial number for the conidial concentration but this was affected by increased inoculum density (size, concentration and mycelial contamination), causing a reduction in the actual number of conidia present, compared to the expected. Up to 40-50% of the conidia in the sprayed suspension could not be accounted for when conidium deposition was on a target. This loss could increase to 90-92% when the weed was sprayed under a crop canopy. [ABSTRACT FROM AUTHOR]

Application of 250 L ha[sup -1] containing 10[sup 7] Alternaria alternata conidia ml [sup -1] caused 61% reduction in dry weight and a 45% mortality in Amaranthus retroflexus plants growing in a wheat crop. However, only 10-22% of the applied conidia were retained on the leaf. In one experiment, conidia remained viable for 4 days on the leaf surface until conditions were favourable for germination. Competition from the wheat crop, as well as its creation of a moist micro-climate, improved the control of Am. retroflexus by A. alternata. Total control of Am. retroflexus may be difficult to achieve with A. alternata, but suppression to reduce or eliminate its competitive effect on crops is possible. [ABSTRACT FROM AUTHOR]

The pathogenicity of Trematophoma lignicola on Amaranthus retroflexus was increased when its conidia were formulated in oilseed rape emulsion. However, this formulation did not reduce the dew period required to allow conidial germination and infection of the host, nor did it protect the conidia from desiccation before the onset of dew. The fungus gave effective control of A. retroflexus plants up to the 4-true-leaf stage. Plants with 5 to 6-true-leaves were infected and their dry weight reduced, but plants with more than 6-true-leaves were unaffected. Plants grown in warm conditions (18-21°C/12-15°C, day/night) were more likely to be successfully controlled than those grown in the cold (10-12°C/7-8°C; day/night). Significant dry weight loss of A. retroflexus plants were achieved at application volumes down to 100 l ha[sup -1] at 5 × 10[sup 6] conidia ml[sup -1]. More effective control was achieved by application of conidia of T. lignicola than mycelial or pycnidial applications. [ABSTRACT FROM AUTHOR]

Formulation of some microbial herbicides in emulsions of vegetable oil can significantly reduce their dependency on long dew periods to allow infection and control of the host weed. Examination of leaves of Viola arvensis, by a range of microscopy techniques, after spraying with an oilin-water emulsion formulation of the potential microbial herbicide Mycocentrospora acerina, suggests that the effect arises as a result of inversion of water into both oil droplets on the leaf surface and oil that penetrates into the leaf tissue. This oil probably mixes with aqueous components from the leaf tissue and, in doing so, forms an invert emulsion. Wesuggest that this supplies the water required by the fungus to initiate and sustain growth so that infection can result. [ABSTRACT FROM AUTHOR]

Alternaria alternata Pesta (gluten matrix) granules stored at 12% relative humidity were still viable and infective, giving total control of Amaranthus retroflexus after 24 months storage. Viability of the propagule in the granule was an important factor of the evaluation test and not just the viability of the granule. The concentration of inoculum in the granule was important, with 10[sup 5] to 10[sup 6] conidia g[sup -1] being the ideal, since lower concentrations may not be able to out-compete the soil micro-flora. Even with soil application, the effect of local humidity was still important. Trematophoma lignicola was also formulated as microbial herbicide granules but the conidia were severely damaged in the production process. [ABSTRACT FROM AUTHOR]

Mycocentrospora acerina (Hartig) Deighton can kill or suppress the growth of Viola arvensis (Murr.) in spring wheat in pot-grown plants in both glasshouse and outdoor studies. The level of damage to V. arvensis and the effect on its competition with wheat were affected by inoculum density and environmental conditions. High inoculum density (105 macroconidia/ml) caused high mortality in V. arvensis and eliminated its competitive effect on wheat. At a lower density (104 macroconidia/ml), the V. arvensis fresh weight and its competition with the wheat were suppressed by up to 38 and 28% respectively, depending on environmental conditions. [ABSTRACT FROM AUTHOR]

Infection by a Drechslera sp. (perfect stage, Pyrenophora chaetomioides (Speg.)), isolated from Bromus sterilis , killed B. sterilis , B. commutatus and B. secalinus. B. diandrus and B. hordeaceus were both infected but not killed. Successful infection required a 24-h dew period. Reduction of the dew period to 8 h significantly reduced the infection of all Bromus spp. tested as determined by leaf necrosis. Inoculation with a low inoculum concentration (2 104 conidia/ml) produced little dry weight reduction, but at 2 105 conidia/ml with an 8-h dew period the dry weights of B. commutatus , B. diandrus , B. secalinus and B. sterilis were reduced by 11-25%. Extending the dew period to 24 h resulted in 77% mortality of B. sterilis and 93% mortality of B. commutatus and B. secalinus. [ABSTRACT FROM AUTHOR]