Effect Of Donor Treatment Research Articles

The allelopathic effects of Festuca paniculata depend on competition in subalpine grasslands

Allelopathy is recognized as an important process in plant–plant interactions, but how it affects plant communities growing in competitive conditions has not been assessed. This article investigates whether the allelopathic effect of Festuca paniculata is modified by competition between target plants in subalpine grasslands. We hypothesized that plants growing in mixed stands will be more affected by allelochemicals than the same species in monoculture. At Lautaret pass (Northern French Alps), a pot experiment was designed. We used leachates from donor pots (Treatments: 1. Bare soil, 2. F. paniculata clipped, and 3. F. paniculata unclipped) to water target pots (Treatments: 1. Control (soil only), 2. Dactylis glomerata, 3. Agrostis capillaris, and 4. D. glomerata and A. capillaris). Target plants were cultivated during one growing season. The effects of leachates from donor pots and interspecific competition in target pots were evaluated by measuring the final biomass of plants. Soil fertility was controlled in all target pots by measuring NO3 −, NH4 +, N, and C % of the soil. Effect of target treatment under bare soil : Both D. glomerata and A. capillaris grew better in monocultures than in mixture. Effect of donor treatment on monocultures : Under bare soil, D. glomerata grew better than under F. paniculata leachates. By contrast, A. capillaris did not respond to donor pot treatment. Effect of donor treatment on mixtures: However, when both species were cultivated together under F. paniculata leachates, the biomass of D. glomerata was similar to that in monoculture under bare soil. Differences in sensitivity to allelopathy reversed the impact of interspecific competition: A. capillaris facilitated D. glomerata under allelopathy, which made allelopathy of F. paniculata on D. glomerata inefficient. The complexity of overlapping mechanisms of plant–plant interactions are highlighted by this semi-natural experiment. In subalpine grasslands, allelopathy not only limits the growth of neighboring plants, but it may also modify community assembly by affecting other plant–plant interactions such as competition. This study contributes to explore the way allelopathy interacts with other plant–plant interactions in natural systems.

The effect of donor treatment with hydrogen on lung allograft function in rats

Because inhaled hydrogen provides potent anti-inflammatory and antiapoptotic effects against acute lung injury, we hypothesized that treatment of organ donors with inhaled hydrogen during mechanical ventilation would decrease graft injury after lung transplantation. Orthotopic left lung transplants were performed using a fully allogeneic Lewis to Brown Norway rat model. The donors were exposed to mechanical ventilation with 98% oxygen plus 2% nitrogen or 2% hydrogen for 3 h prior to harvest, and the lung grafts underwent 4 h of cold storage in Perfadex (Vitrolife, Göteborg, Sweden). The graft function, histomorphologic changes, and inflammatory reactions were assessed. The combination of mechanical ventilation and prolonged cold ischemia resulted in marked deterioration of gas exchange when the donors were ventilated with 2% nitrogen/98% oxygen, which was accompanied by upregulation of proinflammatory cytokines and proapoptotic molecules. These lung injuries were attenuated significantly by ventilation with 2% hydrogen. Inhaled hydrogen induced heme oxygenase-1, an antioxidant enzyme, in the lung grafts prior to implantation, which might contribute to protective effects afforded by hydrogen. Preloaded hydrogen gas during ventilation prior to organ procurement protected lung grafts effectively from ischemia/reperfusion-induced injury in a rat lung transplantation model.

Effect of donor treatment with heparinoids on graft function after intraportal transplantation of a marginal islet mass: An experimental study

Heparinoids interact with factors that are involved in ischemia-reperfusion injury and thus may prevent organ injury. We therefore studied the effects on subsequent intraportal islet transplantation of systemic administration of unfractionated and N-desulphated heparin to donors prior to pancreatectomy. Donor rats were given an intravenous injection of either heparin (1.3 mg/kg or 13.3 mg/kg; 200 U/kg or 2000 U/kg, respectively) or N-desulphated heparin (50 mg/kg; ∼5 U/kg) at 5 to 10 minutes prior to pancreas procurement. Five hundred freshly isolated islets were injected intraportally into syngeneic male Lewis recipients that had developed streptozotocin-induced diabetes. Blood glucose and body weight were monitored for 5 weeks thereafter. Rats transplanted with islets from donors given high dose heparin showed a fall in blood glucose from 25.1 ± 1.4 to 11.0 ± 2.7 mmol/L ( P < .01) with 60% of animals euglycemic within the first week. In contrast, the controls, did not show a fall in glucose levels at 1 week and none had become euglycaemic. Normalization of glycemia was slower in recipients of islets from animals treated with the lower dose of heparin. Results were intermediate with islets from donors given N-desulphated heparin. Nevertheless, all heparinoids used in this study caused more than a doubling of the number of animals achieving normoglycemia by 3 to 4 weeks. We hypothesize that pretreatment of the donor with heparin protects islet integrity during procurement and isolation and hence accelerates islet engraftment and remodelling. Since the effect was seen with N-desulphated heparin, which has negligible anticoagulant properties, we believe the mechanism to be independent of the anticoagulant activity.