Osteogenic lithium-doped brushite cements for bone regeneration.

This study investigated the osteogenic performance of new brushite cements obtained from Li+-doped ß-tricalcium phosphate as a promising strategy for bone regeneration. Lithium (Li+) is a promising trace element to encourage the migration and proliferation of adipose-derived stem cells (hASCs) and the osteogenic differentiation-related gene expression, essential for osteogenesis. In-situ X-ray diffraction (XRD) and in-situ 1H nuclear magnetic resonance (1H NMR) measurements proved the precipitation of brushite, as main phase, and monetite, indicating that Li+ favored the formation of monetite under certain conditions. Li+ was detected in the remaining pore solution in significant amounts after the completion of hydration. Isothermal calorimetry results showed an accelerating effect of Li+, especially for low concentration of the setting retarder (phytic acid). A decrease of initial and final setting times with increasing amount of Li+ was detected and setting times could be well adjusted by varying the setting retarder concentration. The cements presented compressive mechanical strength within the ranges reported for cancellous bone. In vitro assays using hASCs showed normal metabolic and proliferative levels. The immunodetection and gene expression profile of osteogenic-related markers highlight the incorporation of Li+ for increasing the in vivo bone density. The osteogenic potential of Li-doped brushite cements may be recommended for further research on bone defect repair strategies.

Ion-doped Brushite Cements for Bone Regeneration.

Decades of research in orthopaedics has culminated in the quest for formidable yet resorbable biomaterials using bioactive materials. Brushite cements most salient features embrace high biocompatibility, bioresorbability, osteoconductivity, self-setting characteristics, handling, and injectability properties. Such type of materials is also effectively applied as drug delivery systems. However, brushite cements possess limited mechanical strength and fast setting times. By means of incorporating bioactive ions, which are incredibly promising in directing cell fate when incorporated within biomaterials, it can yield biomaterials with superior mechanical properties. Therefore, it is a key to develop fine-tuned regenerative medicine therapeutics. A comprehensive overview of the current accomplishments of ion-doped brushite cements for bone tissue repair and regeneration is provided herein. The role of ionic substitution on the cements physicochemical properties, such as structural, setting time, hydration products, injectability, mechanical behaviour and ion release is discussed. Cell-material interactions, osteogenesis, angiogenesis, and antibacterial activity of the ion-doped cements, as well as its potential use as drug delivery carriers are also presented. STATEMENT OF SIGNIFICANCE: Ion-doped brushite cements have unbolted a new era in orthopaedics with high clinical interest to restore bone defects and facilitate the healing process, owing its outstanding bioresorbability and osteoconductive/osteoinductive features. Ion incorporation expands their application by increasing the osteogenic and neovascularization potential of the materials, as well as their mechanical performance. Recent accomplishments of brushite cements incorporating bioactive ions are overviewed. Focus was placed on the role of ions on the physicochemical and biological properties of the biomaterials, namely their structure, setting time, injectability and handling, mechanical behaviour, ion release and in vivo osteogenesis, angiogenesis and vascularization. Antibacterial activity of the cements and their potential use for delivery of drugs are also highlighted herein.

Bromus species in winter wheat-population dynamics and competitiveness.

The infestation of Bromus species in small grains, especially in winter cereals has increased over recent years. In some areas winter wheat growers consider Bromus spp. as their worst grass weed. Besides yield reduction, Bromus spp. cause lodging and complication of harvest. In Germany the two most dominant species are Bromus sterilis (L.) and Bromus secalinus (L.). In order to develop control strategies the population dynamics of the weeds were investigated. Based on the results a deterministic mathematical model using differential and algebraic equations was used to estimate changes in the population of the two Bromus species.

Recovery of non-target plants affected by airborne herbicides.

This study was conducted to determine the effects of airborne herbicides on the photosynthesis of non-target plants and to interpret and evaluate the observed effects airborne herbicides have on non-target plants. The study involved the exposition of sunflower (Helianthus annuus L.) at different growth stages for 24 h in a wind tunnel to a range of various concentrations (0.012 to 4.104 micrograms/m3) of the herbicide bromoxynil, an inhibitor of photosynthesis. By means of chlorophyll fluorescence induction analysis, the quantum yield of electron transport at photosystem II was calculated as phi PSII = (Fm'-Ft)/Fm'. In order to evaluate the ecological significance of the observed effects, the ability of the plants to recover was investigated. Results show, that their is a risk for sunflower plants of being affected by airborne herbicides; bromoxynil concentrations in ambient air > 0.265 microgram/m3 impair the photosynthetic activity of exposed leaves and accordingly > 0.611 microgram/m3 the photosynthetic activity of newly developed leaves. Compared to monitoring data of bromoxynil in the atmosphere, it can be concluded, that plants remote from agricultural fields may be not affected, whereas plants growing near treated fields are potentially at risk. However, it has to be taken into account that plants are able to recover from injury up to a certain concentration and exposure time. The ability to recover has been found to be related to the growth stage and the development stage of the leaf. Although younger plants are more sensitive than older plants, they can compensate a decrease in the photosynthetic activity better than older plants. Thus, the ability to recover has to be considered, when estimating the ecotoxicological potential of airborne herbicides on non-target plants and consideration should be given to implement this information into a non-target-risk assessment.

Efficacy of Phomopsis convolvulus as a mycoherbicide for Convolvulus arvensis.

The purpose of the investigations was to determine the efficacy of different conidia concentrations of Phomopsis convolvulus Ormeno on different leaf stages of Convolvulus arvensis seedlings and regrowth potential of C. arvensis 25 days after inoculation. Furthermore, the potential of P. convolvulus on the growth of C. arvensis derived from different root lengths was studied. The results showed a great reduction in dry weight of above-ground biomass with more than 80% irrespective of the conidia concentration (1 x 10(6), 10(7) and 10(8) conidia/ml) on plants of the leaf stage 1-3 and 5-7 and gave more than 80% reduction of root biomass with an exception in case of 1 x 10(6) conidia/ml on plants of the leaf stage 9-11. Mortality was reached complete only with 1 x 10(8) conidia/ml on plants of the leaf stage 1-3. Regrowth potential of C. arvensis at more developed leaf stages was higher than at early leaf stages. Within the 3 categories of root lengths tested (5, 10 and 15 cm), the 1-3 leaf stage shoots showed the highest susceptibility to P. convolvulus. Obtained results illustrate that the application of P. convolvulus with 1 x 10(8) conidia/ml at the young leaf stage (1-3 leaf stage) on all treatments give a great reduction of biomass and adversely affects regeneration of the plants.