Combined effects of soil 3D spatial heterogeneity and biotic spatial heterogeneity (plant clumping) on ecosystem processes in grasslands.

Soil heterogeneity has been shown to enhance plant diversity, but its effect on grassland productivity is less clear. Even less is known about the effect of plant clumping (intraspecific aggregation) and its potential interaction with soil heterogeneity. The combined effects of soil 3D spatial heterogeneity and species clumping were experimentally studied in grassland mesocosms consisting of four grassland species. These species were planted in three patterns (i.e. completely mixed, clumped by 9 or 36 individuals of the same species) on soils with heterogeneous cells of alternating nutrient-poor and rich soil differing in size from 0 (mixed soil) to 12, 24, and 48 cm (complete poor or rich mesocosm). Moderate soil cell sizes (12-24 cm) consistently increased whole-mesocosm aboveground productivity by more than 20%, which mainly originated from the increased growth of the plants growing on the poor soil cells. In contrast, total mesocosm productivity was not affected by species clumping although there were some species-specific effects, both of clumping and of the interaction of clumping with soil heterogeneity. Our results show that intermediate soil heterogeneity promotes productivity. Clumping can improve the growth of inferior species, thus promoting coexistence, without affecting overall productivity. We found no interaction effect of clumping and soil heterogeneity on productivity at the community level and some minor species-specific effects.

Phenology and growth of Fagus sylvatica and Quercus robur seedlings in response to temperature variation in the parental versus offspring generation.

Plants are known to respond to warming temperatures. Few studies, however, have included the temperature experienced by the parent plant in the experimental design, in spite of the importance of this factor for population dynamics. We investigated the phenological and growth responses of seedlings of two key temperate tree species (Fagus sylvatica and Quercus robur) to spatiotemporal temperature variation during the reproductive period (parental generation) and experimental warming of the offspring. To this end, we sampled oak and beech seedlings of different ages (1-5 years) from isolated mother trees and planted the seedlings in a common garden. Warming of the seedlings advanced bud burst in both species. In oak seedlings, higher temperatures experienced by mother trees during the reproductive period delayed bud burst in control conditions, but advanced bud burst in heated seedlings. In beech seedlings, bud burst timing advanced both with increasing temperatures during the reproductive period of the parents and with experimental warming of the seedlings. Relative diameter growth was enhanced in control oak seedlings but decreased with warming when the mother plant experienced higher temperatures during the reproductive period. Overall, oak displayed more plastic responses to temperatures than beech. Our results emphasise that temperature during the reproductive period can be a potential determinant of tree responses to climate change.

Morning glory disc anomaly with an ipsilateral enlargement of the optic nerve pathway.

PURPOSE: To report three patients with an unilateral morning glory disc anomaly in association with an ipsilateral mild thickening of the optic nerve. METHODS: Three children with a morning glory disc anomaly underwent a magnetic resonance imaging (MRI) of the brain. Ophthalmological, genetic and MRI findings at follow-up are reported. A literature search on the association of morning glory anomaly in association with optic nerve glioma is reported.1 RESULTS: Three children with an unilateral morning glory anomaly and ipsilateral poor visual acuity were found to have an ipsilateral mild optic nerve enlargement on brain MRI. At serial MRI scanning, there was no progression of this finding. CONCLUSIONS: The morning glory disc anomaly is a rare congenital malformation of the optic disc. It can be associated with central nervous system abnormalities. The association with an optic nerve glioma has been described once before.1 Our three cases confirm the possible association between a morning glory disc anomaly and an ipsilateral optic nerve enlargement. Serial MRI showed no growth at follow-up. The awareness of this association by the ophthalmologists is important.

Virus safety of plasma products using 20 nm instead of 15 nm filtration as virus removing step.

During the manufacture of human plasma derivatives, a series of complementary measures are undertaken to prevent transmission of blood-borne viruses. Virus filtration using 15 nm (Planova15N) filters has successfully been implemented in manufacturing processes for various plasma derivatives primarily because virus filtration is a technique, mild for proteins, that can effectively remove even small non-lipid-enveloped viruses, such as HAV and parvovirus B19. However, the use of 15 nm filters has limitations with regard to protein capacity of the filters and the process flow, resulting in an expensive manufacturing step. Therefore, studies were performed to test whether the use of 20 nm (Planova20N) filters, having different characteristics compared to 15 nm filters, can be an alternative for the use of 15 nm filters. It is shown that 20 nm filtration can be an alternative for 15 nm filtration. However, the virus removal capacity of the 20 nm filters depends on the plasma product that is filtered. Therefore, an optimisation study must be performed with regard to process parameters such as pressure, pH and protein concentration for each plasma product. In this study, using optimised conditions, the virus removal capacity of 20 nm filters appears to be comparable or even better when compared to that of 15 nm filters.

['Evidence-based medicine' in the Dutch and Flemish psychiatric, psychological and psychotherapeutic specialist literature: widely used?]. / 'Evidence-based medicine' in de Nederlandstalige psychiatrische, psychologische en psychotherapeutische vakliteratuur: opvallend aanwezig?

The expression 'evidence-based medicine' was first used in medical journals in the 1990's. Recent research has shown that the expression appears very frequently in international medical publications. Until recently, however, there were no research data concerning the frequency with which the expression is used in the titles and summaries in Dutch and Flemish specialist journals in the field of psychiatry, psychology and psychotherapy. In our systematic review of the Dutch and Flemish specialist medical literature published between 1990 and 2003 we found that the use of the expression increased markedly as from 1997.

Are heat and cold resistance of arctic species affected by successive extreme temperature events?

Extreme temperature events are projected to increase in frequency in a future climate. As successive extremes could occur more frequently, patches of vulnerable tundra vegetation were exposed to two consecutive heat waves (HWs) of 10 d each, with a 5-d recovery period in between. Surface temperatures during the HWs were increased approximately 6 degrees C using infrared irradiation sources. In three of the four target species (Pyrola grandiflora, Polygonum viviparum and Carex bigelowii), plant conditions improved upon the first exposure. Depending on species, leaf relative growth, leaf chlorophyll content or maximal photochemical efficiency was increased. In P. grandiflora the positive effects of the heat on the photosynthetic apparatus led to augmented net photosynthesis. By contrast, Salix arctica responded mainly negatively, indicating species-specific responses. During the second HW, leaf mortality suddenly increased, indicating that the heat stress induced by the extreme events lasted too long and negatively influenced the species resistance to high temperature. After the HWs, when plants were exposed to (low) ambient temperatures again, plant performance deteriorated further, indicating possible loss of cold resistance.

Impact of field margin vegetation and herbage removal on ingrowing and anemochorous weeds.

This research studies the effect of different ways to establish and to maintain unfertilised field margins on the development of potential weed plants and seed dispersal into adjacent crops. Plant communities in field margins either developed spontaneously or were sown with different seed mixtures of grasses and forbs. Margins were mown twice a year and the cuttings were either removed or not. Three years after establishment, the importance of important weeds Elymus repens, Cirsium arvense and Urtica dioica was significantly higher in the unsown community or when cuttings were not removed after mowing. Seed dispersal from the margin into adjacent crops was important in the unsown community during the first year after establishment. Between 82% and 99% of the seeds were disseminated within a distance of 4 m from the margin strip. In order to minimize the dissemination of weed species and invasion by noxious vegetatively propagated weeds it is recommended to establish a field margin by sowing and to remove the cuttings after each mowing cut.

Biodiversity and agro-ecology in field margins.

This multidisciplinary study investigates agro-ecological functions (nature conservation, agriculture, environment) and implications of newly created, mown sown and unsown field margin strips installed on ex-arable land to increase biodiversity. From conservational concern, the development of species rich field margin strips was not strongly affected by the installed type of margin strip since species diversity converged over time, whether strips were sown or not. Convergence between unsown and sown margin strips occurred also in terms of species composition: unsown and sown strips became similar over time. Mowing without removal of cuttings significantly reduced species richness, yielded more grassy margin strips and delayed similarity in species composition between sown and unsown margin strips. Species richness on the longer term was not significantly affected by light regime nor by disturbance despite significant temporary effects shortly after the disturbance event. On the contrary vegetation composition in terms of importance of functional groups changed after disturbance: the share of spontaneous species within functional groups increased resulting in higher similarity between the sown and unsown vegetation. Furthermore risk of invasion was highest in the disturbed unsown community on the unshaded side of a tree lane. A positive effect of botanical diversity on insect number and diversity was found. However the effects of botanical diversity on insect number was mediated by light regime. At high light availability differences between plant communities were more pronounced compared to low light availablilty. The abundance of some insect families was dependent on the vegetation composition. Furthermore light availability significantly influenced insect diversity as well as the spatial distribution of families. From agricultural concern, installing margin strips by sowing a species mixture and a mowing regime with removal of cuttings are good practices to diminish the risk of species ingrowth into adjacent crops by creeping roots and rhizomes. Seed dispersal was only problematic one year after the installation of the field margin strips particularly nearby the unsown margin strip and wind-borne seeds were dispersed over limited distances, mainly within 4 m of field margins. Annual herbage yield was not affected by mowing management. DM yield of sown/unsown communities converged over time. Compared to herbage from an intensively managed fertilized grassland, field margin herbage revealed a low feeding value, owing to a low crude protein content, a low digestibility and a high crude fibre content. The unsown community had a higher forage quality than communities sown to bred commercially available grass varieties. Both digestibility and crude protein content decreased over time irrespective of plant community or location. Mid June cuts were more productive than mid September cuts but digestibility and crude protein content was lower. The use of herbage from field margins as hay for horses or as a component in farmland compost are good alternatives. A strong relation was found between the distribution of pest insects and their antagonist families along field margin strips indicating a status of biological equilibrium. From environmental concern, field margin strips buffered boundary vegetation and watercourses against cropped areas loaded with high levels of mineral nitrogen. Margin strips reduced the mineral nitrogen content of the soil in the margin and mineral nitrogen loss during wintermonths. Mineral nitrogen loss was not affected by field margin type but by distance from the field crop. A minimal width of 5 m is necessary to reach an optimal reduction in mineral soil N and N losses.

The effect of grape-seed extract on 24 h energy intake in humans.

OBJECTIVE: Since grape-seed extract has been shown to stimulate lipolysis in vitro and reduce food intake in rats, we assessed the efficacy of grape-seed extract with respect to energy intake (EI) and satiety. DESIGN: In a randomized, placebo-controlled, double-blind, cross-over study, 51 subjects (age 18-65 y, body mass index 22-30 kg/m2) ate an ad libitum lunch and dinner twice in the University Restaurant for 3 days. Standard breakfasts and snacks were provided. Supplements were taken 30-60 min prior to each meal. RESULTS: In the total study population, no difference in 24 h EI was found between the grape-seed extract and placebo. However, in the subgroup of subjects (n=23) with an energy requirement > or =the median of 7.5 MJ/day, EI was reduced by 4% (DeltaEI 352.1 kJ/24 h, P=0.05) after grape-seed extract compared to placebo treatment. Meanwhile, there were no significant differences in macronutrient composition, attitude towards eating, satiety, mood or tolerance. CONCLUSIONS: Grape seed reduced 24 h EI, with on average 4% in subjects who had an energy requirement > or =7.5 MJ/day, without further effects on satiety, mood or tolerance. These findings suggest that grape seed could be effective in reducing 24 h EI in normal to overweight dietary unrestrained subjects, and could, therefore, play a significant role in body-weight management.

High protein intake sustains weight maintenance after body weight loss in humans.

BACKGROUND: A relatively high percentage of energy intake as protein has been shown to increase satiety and decrease energy efficiency during overfeeding. AIM: To investigate whether addition of protein may improve weight maintenance by preventing or limiting weight regain after weight loss of 5-10% in moderately obese subjects. DESIGN OF THE STUDY: In a randomized parallel design, 148 male and female subjects (age 44.2 +/- 10.1 y; body mass index (BMI) 29.5 +/- 2.5 kg/m2; body fat 37.2 +/- 5.0%) followed a very low-energy diet (2.1 MJ/day) during 4 weeks. For subsequent 3 months weight-maintenance assessment, they were stratified according to age, BMI, body weight, restrained eating, and resting energy expenditure (REE), and randomized over two groups. Both groups visited the University with the same frequency, receiving the same counseling on demand by the dietitian. One group (n=73) received 48.2 g/day additional protein to their diet. Measurements at baseline, after weight loss, and after 3 months weight maintenance were body weight, body composition, metabolic measurements, appetite profile, eating attitude, and relevant blood parameters. RESULTS: Changes in body mass, waist circumference, REE, respiratory quotient (RQ), total energy expenditure (TEE), dietary restraint, fasting blood-glucose, insulin, triacylglycerol, leptin, beta-hydroxybutyrate, glycerol, and free fatty acids were significant during weight loss and did not differ between groups. During weight maintenance, the 'additional-protein group' showed in comparison to the nonadditional-protein group 18 vs 15 en% protein intake, a 50% lower body weight regain only consisting of fat-free mass, a 50% decreased energy efficiency, increased satiety while energy intake did not differ, and a lower increase in triacylglycerol and in leptin; REE, RQ, TEE, and increases in other blood parameters measured did not differ. CONCLUSION: A 20% higher protein intake, that is, 18% of energy vs 15% of energy during weight maintenance after weight loss, resulted in a 50% lower body weight regain, only consisting of fat-free mass, and related to increased satiety and decreased energy efficiency.

A simple method to determine leaf angles of grass species.

There are several very accurate methods to determine leaf angles in closed canopies. However, these are generally very time-consuming or require special equipment. Average canopy leaf angles were derived from simple height and blade length measurements. An exponential relationship between the height/length ratio and the average blade leaf angle was used. The method was tested for two grass species, Dactylis glomerata and Festuca arundinacea, grown under different UV-B levels. The results clearly show that the method is reasonably accurate and able to identify UV-B induced changes in leaf angle. To get these results only 50 measurements of leaf blade height and length were necessary to calculate the allometric relationship, after which 10 length and height measurements from a canopy were used to calculate the average canopy leaf angle.

Intravascular reduction of methemoglobin in plasma of the rat in vivo.

The formation and reduction of extracellular methemoglobin (metHb) in plasma was studied in vivo in conscious rats after isovolemic exchange transfusions with polymerized hemoglobin solutions. After exchange transfusions of 40 and 70% of the blood volume with hemoglobin solutions, containing less than 6% methemoglobin, the methemoglobin level remained below 15%, whereas exchange transfusions of greater than 90% resulted in an increase in the metHb level to about 30% after 24 hours. The reduction of metHb was studied after exchange transfusions with fully oxidized hemoglobin. A gradual decrease in the metHb level to 20% was observed after exchanges of 5 or 40%. A higher exchange transfusion (70%) resulted also in a decrease in the metHb level but only to approximately 40% in 24 hours. In another series of experiments the reduction of metHb was studied in vitro with isolated human erythrocytes. Incubation of the erythrocytes in the presence of oxidized polymerized hemoglobin (3 g%) resulted in a decrease in the percentage of metHb from 91% to 64%. In the presence of 0.2 mM ascorbic acid the metHb level declined to 22%, suggesting a synergistic effect. These results indicate (1) that there is a potent reducing mechanism present in blood that can reduce extracellular oxidized polymerized hemoglobin and (2) that isolated erythrocytes have a large capacity to reduce extracellular metHb, and may also play an important role in the reduction of extracellular metHb in vivo.

Diurnal changes in the response of canopy photosynthetic rate to elevated CO2 in a coupled temperature-light environment.

The relative increase with elevated CO2 of canopy CO2 uptake rate (A), derived from continuous measurements during the day, was examined in full-cover vegetative Lolium perenne canopies after 17 days of regrowth. The stands were grown at ambient (358±50 µmol mol(-1)) and increased (626±50 µmol mol(-1)) CO2 concentration in sunlit growth chambers. Over the entire range of temperature and light conditions (which were strongly coupled and increased simultaneously), A was on average twice as large in high compared to ambient CO2. This response (called M=A in high CO2/A in ambient CO2) could not be explained by changes in canopy conductance for CO2 diffusion (GC). In spite of interaction and strong coupling between temperature and light intensity, there was evidence that temperature rather than light determined M. Further, high CO2 treatment was found to alleviate the afternoon depression in A observed in ambient CO2. A temperature optimum shift or/and a larger carbohydrate sink capacity through altered root/shoot ratio are proposed in explanation.

Leaf and canopy responses of Lolium perenne to long-term elevated atmospheric carbon-dioxide concentration.

The relationship between leaf photosynthetic capacity (p n, max), net canopy CO2- and H2O-exchange rate (NCER and E t, respectively) and canopy dry-matter production was examined in Lollium perenne L. cv. Vigor in ambient (363±30 µl· l(-1)) and elevated (631±43 µl·l(-1)) CO2 concentrations. An open system for continuous and simultaneous regulation of atmospheric CO2 concentration and NCER and E t measurement was designed and used over an entire growth cycle to calculate a carbon and a water balance. While NCERmax of full-grown canopies was 49% higher at elevated CO2 level, stimulation of p n, max was only 46% (in spite of a 50% rise in one-sided stomatal resistance for water-vapour diffusion), clearly indicating the effect of a higher leaf-area index under high CO2 (approx. 10% in one growing period examined). A larger amount of CO2-deficient leaves resulted in higher canopy dark-respiration rates and higher canopy light compensation points. The structural component of the high-CO2 effect was therefore a disadvantage at low irradiance, but a far greater benefit at high irradiance. Higher canopy darkrespiration rates under elevated CO2 level and low irradiance during the growing period are the primary causes for the increase in dry-matter production (19%) being much lower than expected merely based on the NCERmax difference. While total water use was the same under high and low CO2 levels, water-use efficiency increased 25% on the canopy level and 87% on a leaf basis. In the course of canopy development, allocation towards the root system became greater, while stimulation of shoot dry-matter accumulation was inversely affected. Over an entire growing season the root/shoot production ratio was 22% higher under high CO2 concentration.

Effects of elevated atmospheric carbon dioxide on gas exchange and growth of white clover.

Effects of rising atmospheric CO2 concentrations on gas exchange, growth and productivity were investigated on an important grassland species, Trifolium repens L. cv. Blanca. Pure stands of this species were cultivated over an entire growing season in small acrylic greenhouses with an artificial atmosphere of ±367 or ±620 ppm CO2, respectively. Effects on growth and development were examined in a functional growth analysis, while consequences for gas exchange were determined by photosynthesis and transpiration measurements on canopy level. The stands were regularly clipped for production assessment. Canopies grown at high CO2 levels showed an average increase in productivity of almost 75%. Growth analysis indicated development of a larger foliage area as the major cause, particularly in the first days of regrowth after cutting. The growth advantage that began in this stage was maintained or bettered during the following weeks. The difference between gas exchange measurements expressed per unit leaf area and per unit ground area suggested that changes in net photosynthesis and respiration did not contribute to the increase in total yield. Transpiration declined under high CO2 if expressed on a leaf area basis but total canopy transpiration was at least as large as in ambient CO2 due to the larger leaf area. Water-use efficiency calculations on the summer data indicated a 35% improvement with a doubling of CO2 concentration.