Effect of clopidogrel on tissue-plasminogen activator-induced in vitro thrombolysis of feline whole blood thrombi

OBJECTIVE: To determine if clopidogrel enhanced the thrombolytic rate of tissue-plasminogen activator (t-PA) on an in vitro feline whole blood thrombosis model. ANIMALS: 9 purpose-bred cats. PROCEDURE: Blood obtained from cats before (baseline) and after treatment with clopidogrel (75 mg, p.o., q 24 h for 3 days) was anticoagulated with sodium citrate (9:1 volume-to-volume ratio) to which 1 microCi of I125-fibrinogen was added. Thrombi were formed by the addition of calcium chloride and bovine thrombin. Thrombi were placed into autologous plasma to which 0.1 mg of t-PA was added. Plasma samples were collected at different time points to determine the amount of released I125-fibrin split products. Thrombolytic rates were calculated by determining the time to 25%, 50%, and 75% thrombolysis (t25, t50, and t75, respectively). Confidence intervals for t25, t50, and t75 at baseline were compared with those after treatment. RESULTS: There were no significant differences in thrombolytic rates between values obtained at baseline and after clopidogrel treatment (t25, 18.0 vs 18.5 minutes; t50, 63.3 vs 65.6 minutes; and t75, 163.0 vs 170.1 minutes, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Clopidogrel did not have an effect on the rate of thrombolysis of feline whole blood thrombi induced by t-PA in this in vitro model.     

Antiplatelet effects and pharmacodynamics of clopidogrel in cats

OBJECTIVE: To evaluate antiplatelet effects and pharmacodynamics of clopidogrel in cats. DESIGN: Original study. ANIMALS: 5 purpose-bred domestic cats. PROCEDURE: Clopidogrel was administered at dosages of 75 mg, p.o., every 24 hours for 10 days; 37.5 mg, p.o., every 24 hours for 10 days; and 18.75 mg, p.o., every 24 hours for 7 days. In all cats, treatments were administered in this order, with at least 2 weeks between treatments. Platelet aggregation in response to ADP and collagen and oral mucosal bleeding times (OMBTs) were measured before and 3, 7, and 10 days (75 and 37.5 mg) or 7 days (18.75 mg) after initiation of drug administration. Serotonin concentration in plasma following stimulation of platelets with ADP or collagen was measured before and on the last day of drug administration. Platelet aggregation, OMBT, and serotonin concentration were evaluated at various times after drug administration was discontinued to determine when drug effects were lost. RESULTS: For all 3 dosages, platelet aggregation in response to ADP platelet aggregation in response to collagen, and serotonin concentration were significantly reduced and OMBT was significantly increased at all measurement times during drug administration periods. All values returned to baseline values by 7 days after drug administration was discontinued. No significant differences were identified between doses. None of the cats developed adverse effects associated with drug administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of clopidogrel at dosages ranging from 18.75 to 75 mg, p.o., every 24 hours, results in significant antiplatelet effects in cats.     

Antioxidant properties of Fusarium head blight-resistant and -susceptible soft red winter wheat grains grown in Virginia

Fusarium head blight (FHB) has emerged as a major threat to wheat crops around the world, and it has been hypothesized that wheat antioxidants may play a role against Fusarium infections. The current study aimed to determine antioxidant properties of FHB-resistant wheat grains as compared to susceptible wheat. The wheat samples were collected from a single growing location (Warsaw, VA) and the same growing season. The results showed that both FHB-resistant and -susceptible wheat grains exerted strong radical scavenging activities against DPPH* radical [0.91-1.53 micromol of Trolox equivalents (TE)/g], peroxyl radical (15.5-24.5 micromol of TE/g), and hydroxyl radical (15.7-35.8 micromol of TE/g). Their total phenolic contents ranged from 888 to 1117 microg of gallic acid equivalents (GAE)/g. Five phenolic acids including ferulic, syringic, vanillic, caffeic, and p-coumaric acids were determined in soluble and insoluble fractions of wheat grains, altogether with a range of 219-389 microg/g. On average, the FHB-resistant wheat group showed significantly higher average values in DPPH* and hydroxyl radicals scavenging activities (30 and 41% higher, respectively) than the FHB-susceptible wheat group.     

Simulated rainfall evaluation of revegetation/mulch erosion control in the Lake Tahoe basin—3: soil treatment effects

Revegetation, or other erosion control treatments of disturbed soil slopes in forested areas and along highways of the Lake Tahoe basin are directed at reduction of sediment loading to waterways reaching the lake. However, following treatment, little vegetation monitoring, or hydrologic evaluation has been conducted either to determine if the various treatments are successful or to assess the duration of erosion control anticipated in the field. Here, we build upon results from use of the portable rainfall simulator (RS) described in the first two papers of this series to evaluate cover and revegetation treatment effects on runoff rates and sediment concentrations and yields from disturbed granitic and volcanic soils in the basin. The effects of slope on rainfall runoff, infiltration and erosion rates were determined at several revegetated road cut and ski run sites. Rainfall simulation (∼60 mm h⁻¹, approximating a 100‐year, 15‐minute storm) had a mean drop size of ∼2·1 mm and approximately 70 per cent of ‘natural’ rainfall kinetic energy. Measurements of: time to runoff; infiltration; runoff amount; sediment yield; and average sediment concentration were obtained. Runoff sediment concentrations and yields from sparsely covered volcanic and bare granitic soils can be correlated to slope. Sediment concentrations and yields from nearly bare volcanic soils exceeded those from granitic soils by an order of magnitude across slopes ranging from 30–70 per cent. Revegetation, or application of pine‐needle mulch covers to both soil types dramatically decreased sediment concentrations and yields. Incorporation of woodchips or soil rehabilitation that includes tillage, use of amendments (biosol, compost) and mulch covers together with plant seeding resulted in little or no runoff or sediment yield from both soils. Repeated measurements of sediment concentrations and yields in the subsequent two years following woodchip or soil rehabilitation treatments continued to result in little or no runoff. Revegetation treatments involving only use of grasses to cover the soils were largely ineffective due to sparse sustainable coverage (< 35 per cent) and inadequate infiltration rates. Copyright © 2005 John Wiley & Sons, Ltd.     

Cubic AgPb(m)SbTe(2+m): bulk thermoelectric materials with high figure of merit

The conversion of heat to electricity by thermoelectric devices may play a key role in the future for energy production and utilization. However, in order to meet that role, more efficient thermoelectric materials are needed that are suitable for high-temperature applications. We show that the material system AgPb(m)SbTe(2+m) may be suitable for this purpose. With m = 10 and 18 and doped appropriately, n-type semiconductors can be produced that exhibit a high thermoelectric figure of merit material ZTmax of approximately 2.2 at 800 kelvin. In the temperature range 600 to 900 kelvin, the AgPb(m)SbTe(2+m) material is expected to outperform all reported bulk thermoelectrics, thereby earmarking it as a material system for potential use in efficient thermoelectric power generation from heat sources.     

Development and validation of a food-frequency questionnaire for the determination of detailed fatty acid intakes

OBJECTIVE: To validate a fat intake questionnaire (FIQ) developed to assess habitual dietary intake while focusing on the assessment of detailed fatty acid intake including total trans unsaturated fatty acids (TUFA). DESIGN: An 88 food item/food group FIQ was developed using a meal pattern technique. Validation was achieved by comparison with dietary intake assessed by a modified diet history (DH) in a cross-over design. Eighty-four individuals supplied adipose tissue biopsies for linoleic acid and total TUFA analysis as an independent validation of the FIQ and DH. SETTING: Medical Centre, Dublin Airport, Republic of Ireland. SUBJECTS: One hundred and five healthy volunteers (43 females and 62 males aged 23-63 years). RESULTS: Significant correlations (P<0.0005) were achieved for intakes of energy (0.78), total fat (0.77), saturated fat (0.77), monounsaturated fat (0.63), polyunsaturated fat (0.73), TUFA (0.67) and linoleic acid (0.71) assessed by the FIQ compared with the DH. Linoleic acid intake assessed by the FIQ and the DH was significantly correlated with adipose tissue concentrations (r=0.58 and 0.49, respectively; P<0.005); however, total TUFA intake was poorly correlated with adipose tissue concentrations (r=0.17 and 0.10 for FIQ and DH, respectively). CONCLUSIONS: The FIQ compared favourably with the DH in assessing habitual diet, in particular fatty acid intake. In addition, the FIQ was successfully validated against the linoleic acid composition of adipose tissue, an independent biomarker of relative fatty acid status. The FIQ could therefore be used as an alternative to the DH as it is a shorter, less labour-intensive method.