Search Results - (Author, Cooperation:J. Roelofs)

2013-05-07

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Adenosine Triphosphatases/chemistry/genetics/metabolism ; Adenosine Triphosphate/metabolism ; Binding Sites ; Carrier Proteins/metabolism ; Cryoelectron Microscopy ; Holoenzymes/chemistry/metabolism ; Models, Molecular ; Molecular Chaperones/*metabolism ; Proteasome Endopeptidase Complex/*chemistry/genetics/*metabolism ; Protein Conformation ; Recombinant Fusion Proteins/chemistry/genetics/metabolism ; Saccharomyces cerevisiae/enzymology/genetics/growth & development/*metabolism ; Saccharomyces cerevisiae Proteins/chemistry/genetics/*metabolism

2018-02-23

American Society of Hematology (ASH)

0006-4971

1528-0020

Biology

Medicine

Immunobiology and Immunotherapy, Platelets and Thrombopoiesis

2018-08-07

The American Association of Immunologists (AAI)

0022-1767

1550-6606

Medicine

1526-100X

Blackwell Publishing Journal Backfiles 1879-2005

Biology

In the Netherlands, the characteristic flora of shallow softwater lakes has declined rapidly as a consequence of eutrophication, alkalization and acidification. The sediment of most lakes has become nutrient rich and anaerobic. We expected that, if a vital seed bank was still present, restoration of the original water quality and sediment conditions would lead to the return of softwater macrophytes. The restoration of 15 degraded, shallow, softwater lakes in the Netherlands was monitored from 1983 to 1998. In eutrophied as well as in acidified lakes, removal of accumulated organic matter from the sediment and shores was followed by rapid recolonization of softwater macrophytes present in the seedbank. After isolation from alkaline water and subsequent mud removal, this recovery was also observed in alkalized lakes. Further development of softwater vegetation correlated strongly with the water quality. When renewed eutrophication was successfully prevented, softwater macrophytes could expand. However, in acidified lakes, Juncus bulbosus and Sphagnum species became dominant after restoration. Liming of an acidified lake was followed by re-acidification within 3 years. Recolonization by softwater macrophytes was inhibited by high turbidity of the water column and spreading of large helophytes on the shore. As an alternative, controlled inlet of alkaline, nutrient-poor groundwater was studied in a few lakes. The pH of those lakes increased, the carbon and nitrogen availability decreased and softwater macrophytes returned. Successful restoration has contributed considerably to maintaining biodiversity in softwater lakes in the Netherlands.

Electronic Resource

1365-2427

Blackwell Publishing Journal Backfiles 1879-2005

Biology

SUMMARY. 〈list xml:id="l1" style="custom"〉1 Considerable changes in macrophyte vegetation can be noticed in 146 originally soft waters, when data on the recent aquatic vegetation are compared with historical information from the period 1900–60. Changes in nutrient status (N, P and C) and accumulation of organic material can be regarded as the operative factors.2 The processes observed in soft waters are acidification, eutrophication and water hardening. Which process dominates depends on the type of soft water.3 Acidification as well as eutrophication of water bodies may ultimately result in the total disappearance of all aquatic macrophytes, with the exception of the floating-leaved nymphaeids Nymphaea alba L. and Nuphar lutea (L.) Sm. Observed successional stages are described and summarized.

Electronic Resource

1476-4687

Nature Archives 1869 - 2009

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

[Auszug] Fig. 1. Phase shift of foremost human visual mechanisms. Subject F.V., left (leading)pupil. Frequencies are plotted on a parabolic scale Fig. 2. Attenuation of foremost human visual mechanisms. Same conditions as Fig. 1.Ordinate shows current amplitude divided by corresponding modulation depth of ...

Electronic Resource

0301-0511

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Psychology

Electronic Resource

1432-1904

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Natural Sciences in General

Abstract   El Niño is well known to affect marine fishery. The Southern Oscillation, however, may also have a strong effect on riverine fish production in floodplains via its effect on river discharge. In years with high river discharges larger parts of the floodplain are inundated, increasing the surface area of suitable nursery grounds for young fish stock. In this way high river discharges are thought to have a positive effect on fish production, while low discharges are thought to have a negative effect. The collapse of the sábalo fishery in the Pilcomayo River in Bolivia, for instance, can be attributed to the 1990–1995 El Niño event and subsequent overexploitation of the fish stocks.

Electronic Resource

1432-0827

Springer Online Journal Archives 1860-2000

Biology

Medicine

Physics

Electronic Resource

1420-9071

Acidification ; nitrogen enrichment ; nutrient leaching ; heathland vegetation ; afforestation

Springer Online Journal Archives 1860-2000

Biology

Medicine

Summary As research on the effects of acidification on healthlands is scarce, the data discussed mainly concern western Europe and particularly the Netherlands. The change from heather into grass dominated healthlands appeared to be caused by the high atmospheric nitrogen enrichment. Acidification of oligotrophic, poorly buffered pools in heathland areas finally results in the disappearance of all submerged plant species, caused by the too low CO2 levels in the water layer. The vitality of the pine-forests decreases; apart from the premature shedding of needles as a result of nutrient deficiences, they become more susceptible to secondary stress factors such as NH3, O3, drought and fungal diseases.

Electronic Resource

1573-2932

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Abstract In large regions of Europe and eastern North America atmospheric deposition of inorganic nitrogen (N) compounds has greatly increased the natural external supply to forest ecosystems. This leads to N saturation, in which availability of inorganic N is in excess of biological demand and the ecosystem is unable to retain all incoming N. The large-scale experiments of the NITREX project (NITRogen saturation EXperiments) are designed to provide information regarding the patterns and rates of responses of coniferous forest ecosystems to increases in N deposition and the reversibility and recovery of impacted ecosystems following reductions in N deposition. The timing of ecosystem response generally followed a hypothesized “cascade of response”. In all sites N outputs have responded markedly but to very different degrees within the first three years of treatment. Within this time significant effects on soil processes and on vegetation have only been detected at two sites. This delayed response is explained by the large capacity of the soil system to buffer the increased N supply by microbial immobilization and adsorption. We believe that this concept provides a framework for the evaluation and prediction of the ecosystem response to environmental change.

Electronic Resource

1573-2932

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Abstract Enclosure experiments have been carried out in two shallow acidified moorland pools in order to study the effects of liming on the water chemistry. The addition of buffering substances (sodium bicarbonate and calcium chloride or powdered marlstone) to enclosures in the Ven bij Schaijk, an oligotrophic acidified moorland pool with a mineral sediment, did not demonstrate internal eutrophication. After addition of NaHCO3 and CaCl2 the pH and alkalinity increased and all macronutrient concentrations, such as that of phosphate, remained low. After treatment with powdered marlstone, there was only a slight increase of pH and alkalinity, due to the slow weathering of marlstone. The alkalinity in this moorland pool remained more stable on a mineral sandy substrate than on an organic substrate, probably as a result of a higher acid release from the organic sediment. In enclosures in the Padvindersven, an eutrophied, acidified moorland pool with an organic gyttja-type of sediment, internal eutrophication took place after adding buffering substances. The phosphate concentration and turbidity of the water increased significantly after treatments with NaHCO3 and CaCl2 as well as with powdered marlstone. The acid release was even higher than from the organic sediment from the Ven bij Schaijk. It was concluded from these experiments that in case of the Ven bij Schaijk, liming with marlstone would be a sufficient way to restore the original water chemistry. In the Padvindersven, however, recovery of the non acidified poorly buffered conditions is only possible by liming in combination with the removal of the organic top layer of the sediment.

Electronic Resource

1573-5052

Cirsio-Molinietum ; C/N ratios ; Ericetum tetralicis ; Hydrology ; Phosphorus availability ; Sod cutting

Springer Online Journal Archives 1860-2000

Biology

Abstract The wet heathland communities of the Ericetum tetralicis and the Cirsio-Molinietum have declined in the Netherlands due to acidification, eutrophication and lowering of the water table. To investigate the prospects of restoration of both communities, the effects of sod cutting and hydrological measures on vegetation and soil chemistry were studied in two nature reserves where these plant communities occurred decades ago. The combination of sod cutting and hydrological measures has restored several rare, groundwater dependent heathland communities. Sod cutting has restored the Ericetum tetralicis, but not the Cirsio-Molinietum. This might be due to the absence of viable seeds of characteristic species of the Cirsio-Molinietum and/or the absence of optimal site conditions, especially high phosphorus concentrations in the top soil. The high phosphorus concentrations might be a consequence of high mineralization rates and/or prolonged inundation with iron-poor water and the decreased flux of iron-rich groundwater into the topsoil. Restoration of the Cirsio-Molinietum only seems possible when sod cutting is carried out together with hydrological measures that counter prolonged inundation and reinforce the discharge of base and iron-rich groundwater.

Electronic Resource

1573-3432

Springer Online Journal Archives 1860-2000

Psychology

Abstract This study compared the visual ERPs and concurrently measured fixation times of autistic children with those of normal children and two psychiatric control groups (socalled “externalizers” and “internalizers”). Autistic children had, in contrast with normal control groups, smaller P3 waves (occipital maximum) to visual target stimuli but did not differ in this respect from the two psychiatric control groups. When the autistic group was split into “good” and “bad” performers, the latter group had significantly smaller amplitudes than the former. No difference was found between the groups in electrophysiological reactivity to the first, novel stimulus of a habituation series. However, an unexpected change in stimulus location induced an increased Fz N400 in the normal group but not in the autistic group or the two psychiatric control groups. In addition, in a non-task-relevant habituation condition, the autistic group fixated complex visual stimuli for shorter times and had smaller occipital P3 waves than the control groups. Analysis of covariance showed that the smaller P3s could not be explained by the shorter fixation times. In none of the ERP parameters were there differences in habituation rate between the controls and the autistic children.

Electronic Resource

1573-2568

noncardiac chest pain ; gastroesophageal reflux ; esophageal motor abnormalities ; 24-hour pressure recording ; pH recording ; time windows ; symptom analysis

Springer Online Journal Archives 1860-2000

Medicine

Abstract Since noncardiac chest pain is the only well-established indication for 24-hr esophageal pH and pressure recording, the analysis of the association between chest pain episodes and esophageal motility abnormalities or reflux is the most important part of data analysis in 24-hr monitoring. Until now, different time windows have arbitrarily been used by various research groups. The aim of this study was to determine the optimal time window for symptom analysis in 24-hr esophageal pH and pressure monitoring. For this purpose repetitive symptom association analysis was carried out, using time windows of various onsets and durations. For each time window, the symptom indices for reflux and dysmotility were calculated. The symptom index for both reflux and dysmotility showed a gradual increase for windows with increasingly early onset, following a pattern that would be predicted on the basis of Poisson's theory. However, both indices had a relatively sharp cutoff point at 2 min before the onset of pain. Both indices only showed a predictable gradual increase when the time window starting at −2 min was extended beyond the moment of pain onset. It is concluded that the optimal time window for symptom analysis in 24-hr esophageal pH and pressure recording begins at 2 min before the onset of pain and ends at the onset of pain.

Electronic Resource

1573-2568

Springer Online Journal Archives 1860-2000

Medicine

Electronic Resource

1573-2568

stomach ; dyspepsia ; diabetes mellitus

Springer Online Journal Archives 1860-2000

Medicine

Abstract In the present study the function of the proximal stomach and its role in eliciting dyspeptic symptoms were evaluated in patients with diabetes mellitus. Eight type I diabetics with cardiovascular autonomic neuropathy and dyspeptic symptoms, and 10 healthy volunteers were studied using an electronic barostat device connected to a intragastric bag. The intragastric bag was inflated and deflated by stepwise pressure increments, creating pressurevolume curves. During the experiment the blood glucose concentrations were maintained within the euglycemic range in the diabetics. The volume-pressure curves showed a larger volume during the pressure increase in the diabetics than in the controls (P〈0.01). This resulted in a significant difference in compliance (dV/dP), 57.2±4.2 ml/mm Hg in diabetics and 43.7±3.5 ml/MM Hg in controls (P〈0.014). The volume-pressure curves during deflation of the intragastric balloon were different from the curves during inflation, creating a hysteresis loop. The area between the inflation and deflation curves was 827 ml/mm Hg in diabetics and 627 ml/mm Hg in the controls (P=0.21). Gastric distension induced more upper gastrointestinal sensations in the patients than in the volunteers: nausea (P〈0.002), bloating (P〈0.003), upper abdominal pain (P〈0.001). In conclusion: this study showed that the compliance of the proximal stomach is increased in diabetic patients with autonomic neuropathy and gastrointestinal symptoms. This abnormality, probably due to autonomic neuropathy, is associated with increased symptom generation during gastric distension.

Electronic Resource

1573-2568

MOTOR ACTIVITY ; DIABETES MELLITUS ; NEUROPATHY

Springer Online Journal Archives 1860-2000

Medicine

Abstract Disordered gastric emptying occurs in 30-50% ofpatients with diabetes mellitus. Although the rate ofgastric emptying is dependent on the integration ofmotor activity in different regions of the stomach, there is limited information about the functionof the proximal stomach in diabetes mellitus. In thepresent study the response of the proximal stomach to aliquid meal was examined in eight diabetic patients with autonomic neuropathy and gastrointestinalsymptoms and in 10 healthy volunteers, using anintragastric bag connected to an electronic barostat.Postprandial relaxation of the proximal stomach wasmeasured as an increase of intragastric bag volume at aconstant pressure level of 1 mm Hg above theintraabdominal pressure. During the experiment the bloodglucose levels were maintained within the euglycemic range. Before ingestion of the meal theintragastric bag volume was larger in the diabeticpatients than in the healthy volunteers, 234.4 ±29.1 ml vs 155.3 ± 15.3 ml (P = 0.06). Themaximum volume was not different in diabetics compared to the healthy controls(386.3 ± 45.2 ml versus 399.0 ± 35.2 ml).However, the maximum volume increase was significantlyless in diabetics (143.7 ± 38.6 ml) compared tothe controls (231.4 ± 30.5 ml, P 〈 0.04). Bloatingwas inversely correlated with the volume changes, whichsuggests that impaired relaxation of the proximalstomach may play a role in the genesis of thissensation. In conclusion, this study shows a lower fastingfundal tone and a decrease in volume change of thegastric fundus after a nutrient drink in patients withautonomic neuropathy due to type I diabetes mellitus. These abnormalities may play a role in theabnormal distribution of food, disordered liquid gastricemptying, and in the genesis of the sensation ofbloating observed in these patients.

Electronic Resource

1573-5036

acidification ; Calluna vulgaris ; chemical soil-composition ; decline of herbaceous heathland species ; eutrophication ; Erica tetralix ; Molinia caerulea

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract High atmospheric deposition of ammonium affects the physical and chemical status of the soil, increasing nitrogen availability, soil acidity and the mobilization of toxic metal ions. To investigate whether and how the decline of several herbaceous plant species in Dutch heathlands is associated with these processes, the chemical composition of the soil on which these species grow has been compared with the soil on which heathland species such asCalluna vulgaris (L.) Hull,Erica tetralix L. andMolinea caerulea (L.) Moench dominate. The discrimination between both soil types was primarily based on differences in pH (H2O), pH (NaCl) and the aluminium/calcium ratio in the waterextracts. Within the group of endangered herbaceous heathland species these soil parameters also varied. This led to a division into 4 groups of species: u Dominating species growing on acid soils Herbaceous species growing together with dominating species on acid soils Herbaceous species growing together with dominating species on moderately acid soils Herbaceous species growing together with dominating species on weakly acid soils. This study indicated that, unlike the decline of heather species, the decline of herbaceous species is not likely to be due to increased competition from grass species as a result of eutrophication. Soil acidification and the changed mineral balance in the soil are most likely to be responsible for the decline of all three groups of herbaceous plant species. ei]R F Huettl

Electronic Resource

1573-5036

Acidification ; Air pollution ; Aluminium ; Ammonium sulphate ; Nitrification ; Nutrient leaching ; Pinus nigra var.Maritima ; Potassium deficiency

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Summary As a result of air pollution, considerable deposition of ammonium sulphate occurs on vegetation and soil in the vicinity of chicken farms and fields dressed with animal slurry. A clear relation exists between this ammonium sulphate deposition and the distance to certain agricultural activities. Field investigations and ecophysiological experiments both show that the needles ofPinus nigra var.maritima (Ait.) Melville take up ammonium and excrete potassium, magnesium and calcium. This often results in potassium and/or magnesium deficiencies and may lead to premature shedding of needles. The high levels of nitrogen in the needles are strongly correlated to fungal diseases. Whether the observed cation leaching will result in disturbed nutrient budgets depends mainly on soil conditions. Leaching of K, Mg and Ca from the soil, caused by ammonium sulphate, may further inhibit nutrient uptake. Field investigations show a clear correlation between increased ratios of NH4 to K, Mg and Ca in the soil solution and the damage to pine forests.

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