Nitrogen nutrition effects on development, growth and nitrogen accumulation of vegetables

In order to be able to match nitrogen supply and nitrogen requirement of vegetable crops, insight is necessary in the responses to nitrogen of important processes of growth and development. This study focused on effects of amount of nitrogen applied and fractionation of nitrogen supply on leaf attributes, accumulation and partitioning of dry matter and nitrogen in potato (Solanum tuberosum L.), Brussels sprouts ( Brassica oleracea L. var gemmifera DC), leek ( Allium porrum L.) and spinach ( Spinacia oleracea L.). Effects of amount of nitrogen applied were always much more important than effects of fractionation of nitrogen supply. Rate of leaf appearance varied among crops from 0. 15-0.60 leaves d -1; it increased with more nitrogen in Brussels sprouts and spinach. Rates of leaf senescence were enhanced by nitrogen in Brussels sprouts. Life span of leaves was about 70 d for all crops. Rates of leaf expansion and maximum sizes of leaves increased with leaf number until a certain leaf number after which they gradually decreased. Both characteristics increased with more nitrogen. Duration of leaf expansion varied among crops from 18-40 d and decreased in Brussels sprouts with more nitrogen. Maximum size of a leaf was mainly determined by rate of leaf expansion. Except in potato, more nitrogen increased specific leaf area. Differences among nitrogen treatments in total green leaf area reflected the effects of nitrogen on rates of leaf expansion.Total dry matter production was strongly related to leaf area duration. Although more nitrogen applied resulted in more nitrogen taken up and more total dry matter produced, considerable variation was observed in the relation between total nitrogen uptake and total dry matter production. Harvest indices for dry matter varied among crops and treatments from about 0.10-0.87; more nitrogen increased it for Brussels sprouts, but decreased it for leek. Harvest indices for nitrogen varied from about 0.22-0.86; more nitrogen increased it for Brussels sprouts. In general, organic nitrogen concentration increased with increasing node number for leaf blades, petioles and leaf sheaths but not for sprouts. The gradient with node number resulted from a decreasing nitrogen concentration during the leafs life. High nitrate concentrations in the marketable produce were only observed in spinach. Nitrate nitrogen concentrations of leaf blades, petioles and leaf sheaths decreased with increasing leaf number at any time of observation, but were not related to leaf age. However, in stems of Brussels sprouts and stems and tubers of potato, total nitrogen and nitrate nitrogen concentration were closely related.The present findings elucidate the reactions of the crops to nitrogen fertilisation. This is helpful for the fine-tuning of nitrogen fertilisation and to develop modules on plant development in crop simulation models

Assessment of bone ingrowth potential of biomimetic hydroxyapatite and brushite coated porous E-beam structures

The bone ingrowth potential of biomimetic hydroxyapatite and brushite coatings applied on porous E-beam structure was examined in goats and compared to a similar uncoated porous structure and a conventional titanium plasma spray coating. Specimens were implanted in the iliac crest of goats for a period of 3 (4 goats) or 15 weeks (8 goats). Mechanical implant fixation generated by bone ingrowth was analyzed by a push out test. Histomorphometry was performed to assess the bone ingrowth depth and bone implant contact. The uncoated and hydroxyapatite-coated cubic structure had significantly higher mechanical strength at the interface compared to the Ti plasma spray coating at 15 weeks of implantation. Bone ingrowth depth was significantly larger for the hydroxyapatite- and brushite-coated structures compared to the uncoated structure. In conclusion, the porous E-beam surface structure showed higher bone ingrowth potential compared to a conventional implant surface after 15 weeks of implantation. Addition of a calcium phosphate coating to the E-beam structure enhanced bone ingrowth significantly. Furthermore, the calcium phosphate coating appears to work as an accelerator for bone ingrowth

The role of tunneling in enzyme catalysis of C–H activation

AbstractRecent data from studies of enzyme catalyzed hydrogen transfer reactions implicate a new theoretical context in which to understand C–H activation. This is much closer to the Marcus theory of electron transfer, in that environmental factors influence the probability of effective wave function overlap from donor to acceptor atoms. The larger size of hydrogen and the availability of three isotopes (H, D and T) introduce a dimension to the kinetic analysis that is not available for electron transfer. This concerns the role of gating between donor and acceptor atoms, in particular whether the system in question is able to tune distance between reactants to achieve maximal tunneling efficiency. Analysis of enzyme systems is providing increasing evidence of a role for active site residues in optimizing the inter-nuclear distance for nuclear tunneling. The ease with which this optimization can be perturbed, through site-specific mutagenesis or an alteration in reaction conditions, is also readily apparent from an analysis of the changes in the temperature dependence of hydrogen isotope effects

Molecular characterization of mutant TP53 acute myeloid leukemia and high-risk myelodysplastic syndrome

Substantial heterogeneity within mutant TP53 acute myeloid leukemia (AML) and myelodysplastic syndrome with excess of blast (MDS-EB) precludes the exact assessment of prognostic impact for individual patients. We performed in-depth clinical and molecular analysis of mutant TP53 AML and MDS-EB to dissect the molecular characteristics in detail and determine its impact on survival. We performed next-generation sequencing on 2200 AML/MDS-EB specimens and assessed the TP53 mutant allelic status (mono- or bi-allelic), the number of TP53 mutations, mutant TP53 clone size, concurrent mutations, cytogenetics, and mutant TP53 molecular minimal residual disease and studied the associations of these characteristics with overall survival. TP53 mutations were detected in 230 (10.5%) patients with AML/MDS-EB with a median variant allele frequency of 47%. Bi-allelic mutant TP53 status was observed in 174 (76%) patients. Multiple TP53 mutations were found in 49 (21%) patients. Concurrent mutations were detected in 113 (49%) patients. No significant difference in any of the aforementioned molecular characteristics of mutant TP53 was detected between AML and MDS-EB. Patients with mutant TP53 have a poor outcome (2-year overall survival, 12.8%); however, no survival difference between AML and MDS-EB was observed. Importantly, none of the molecular characteristics were significantly associated with survival in mutant TP53 AML/MDS-EB. In most patients, TP53 mutations remained detectable in complete remission by deep sequencing (73%). Detection of residual mutant TP53 was not associated with survival. Mutant TP53 AML and MDS-EB do not differ with respect to molecular characteristics and survival. Therefore, mutant TP53 AML/MDS-EB should be considered a distinct molecular disease entity

Gall-bladder dysmotility - A risk factor for gall-stone formation in hypertriglyceridaemia and reversal on triglyceride-lowering therapy with bezafibrate and fish oil

Doel: Onderzoeken van de pathofysiologische mechanismen die de kans op galstenen verhogen bij hypertriglyceridemie (HTG) en het vergelijken van de effecten van triglycerideverlagende therapie met bezafibraat en visolie op determinanten van cholelithiasis (biliaire lipidesamenstelling en galblaasmotoriek) bij HTG-patiënten.Opzet: Gekruiste opzet met ‘random’-volgorde.Patiënten en methoden: De galblaasmotoriek werd postprandiaal en tijdens cholecystokinine(CCK)-infusie echografisch onderzocht. De determinanten van cholelithiasis en de serumlipiden werden vergeleken tussen 9 HTG-patiënten en 10 normolipidemische controlepersonen van hetzelfde geslacht, dezelfde leeftijd en ‘body mass’-index. Bij de HTG-patiënten werden de effecten van bezafibraat en gezuiverde omega-3-olie (‘visolie’) bepaald.Resultaten: De serumtriglyceride(TG)-spiegel van de HTG-patiënten was 14-voudig verhoogd, vergeleken met de controlepersonen. De lipidesamenstelling van de gal, de nuchtere galblaasvolumen en de serum-CCK-spiegels verschilden niet tussen HTG-patiënten en controlepersonen. De galblaaslediging was verminderd bij HTG-patiënten versus controlepersonen tijdens CCK-infusie (–22) en ook na een maaltijd (–37; beide p &lt; 0,001). De postprandiale serum-CCK-spiegels waren significant hoger bij HTG-patiënten. Zowel bezafibraat als visolie verlaagde de serum-TG-spiegel (–68 en –51 ten opzichte van de uitgangswaarde; beide: p &lt; 0,01). Nuchtere CCK-spiegels verschilden niet, terwijl de CCK-geïnduceerde galblaaslediging onder bezafibraat toenam met 29 (p &lt; 0,001) en met visolie met 13 (p = 0,07). De postprandiale galblaasmotoriek verbeterde tijdens zowel bezafibraat- (+47) als visoliebehandeling (+25; beide: p &lt; 0,02), waarschijnlijk gedeeltelijk door een toegenomen gevoeligheid van de galblaas voor CCK (voor beide: p &lt; 0,05 vergeleken met de uitgangsfase). Bezafibraat, in tegenstelling tot visolie, verhoogde de molaire cholesterol-galzuurratio (+40; p ≤ 0,05), terwijl beide behandelingen geen effect hadden op de cholesterolsaturatie-index.Conclusies: De verminderde galblaasmotoriek bij HTG-patiënten lijkt het gevolg te zijn van verminderde gevoeligheid voor CCK, wat kan bijdragen aan het verhoogde risico op galsteenvorming. Bij HTG-patiënten verbetert triglycerideverlagende therapie met visolie of bezafibraat de verminderde galblaasmotoriek zonder nadelig effect op de biliaire cholesterolverzadiging.Objective. To unravel the mechanisms responsible for the increased risk of gall-stone disease in hypertriglyceridaemia (HTG) and to compare the effects of triglyceride-lowering therapy with bezafibrate and fish oil on determinants of cholelithiasis (biliary-lipid composition and gall-bladder motility) in HTG patients. Design. Randomised cross over. Patients and methods. Gall-bladder motility (ultrasonography) was studied postprandially and during infusion of cholecystokinin (CCK). Determinants of cholelithiasis and serum lipids were compared between 9 HTG patients and 10 age, sex and body-mass index matched normolipidaemic controls. The effects of bezafibrate and purified omega-3-oil ('fish oil') in HTG patients were studied. Results. HTG patients showed 14-fold higher serum-triglyceride (TG) levels than controls. Biliary-lipid composition, fasting gall-bladder volumes, and CCK levels did not differ between HTG patients and controls. Gall-bladder emptying was reduced in HTG patients compared with controls during CCK infusion (-22%) as well as in response to a meal (-37%; both p &lt; 0.001). Postprandial CCK levels were significantly higher in HTG patients. Both bezafibrate and fish oil reduced serum TG levels (-68 and -51% versus baseline, respectively; both p &lt; 0.01). Fasting CCK levels were not affected whereas CCK-induced gall-bladder emptying increased during bezafibrate (+29%; p &lt; 0.001) and tended to increase upon fish-oil therapy (+13%; p = 0.07). Postprandial gall-bladder motility improved at least partly with bezafibrate and fish oil (+47 and +25% versus baseline, respectively; both p &lt; 0.02) due to increased gallbladder sensitivity to CCK (both p &lt; 0.05 versus baseline). Bezafibrate but not fish oil increased the molar ratio of cholesterol to bile acids (+40%; p ≤ 0.05), but no effects on the cholesterol-saturation index were seen with either treatment. Conclusions. We suggest that impaired gall-bladder motility occurs in HTG patients due to decreased sensitivity to CCK, which may add to the enhanced risk of gall-stone disease in HTG patients. Triglyceride-lowering therapy by both fish oil and bezafibrate improves gall-bladder dysmotility without adversely affecting biliary-cholesterol saturation.</p

Gall-bladder dysmotility - A risk factor for gall-stone formation in hypertriglyceridaemia and reversal on triglyceride-lowering therapy with bezafibrate and fish oil

Doel: Onderzoeken van de pathofysiologische mechanismen die de kans op galstenen verhogen bij hypertriglyceridemie (HTG) en het vergelijken van de effecten van triglycerideverlagende therapie met bezafibraat en visolie op determinanten van cholelithiasis (biliaire lipidesamenstelling en galblaasmotoriek) bij HTG-patiënten.Opzet: Gekruiste opzet met ‘random’-volgorde.Patiënten en methoden: De galblaasmotoriek werd postprandiaal en tijdens cholecystokinine(CCK)-infusie echografisch onderzocht. De determinanten van cholelithiasis en de serumlipiden werden vergeleken tussen 9 HTG-patiënten en 10 normolipidemische controlepersonen van hetzelfde geslacht, dezelfde leeftijd en ‘body mass’-index. Bij de HTG-patiënten werden de effecten van bezafibraat en gezuiverde omega-3-olie (‘visolie’) bepaald.Resultaten: De serumtriglyceride(TG)-spiegel van de HTG-patiënten was 14-voudig verhoogd, vergeleken met de controlepersonen. De lipidesamenstelling van de gal, de nuchtere galblaasvolumen en de serum-CCK-spiegels verschilden niet tussen HTG-patiënten en controlepersonen. De galblaaslediging was verminderd bij HTG-patiënten versus controlepersonen tijdens CCK-infusie (–22) en ook na een maaltijd (–37; beide p &lt; 0,001). De postprandiale serum-CCK-spiegels waren significant hoger bij HTG-patiënten. Zowel bezafibraat als visolie verlaagde de serum-TG-spiegel (–68 en –51 ten opzichte van de uitgangswaarde; beide: p &lt; 0,01). Nuchtere CCK-spiegels verschilden niet, terwijl de CCK-geïnduceerde galblaaslediging onder bezafibraat toenam met 29 (p &lt; 0,001) en met visolie met 13 (p = 0,07). De postprandiale galblaasmotoriek verbeterde tijdens zowel bezafibraat- (+47) als visoliebehandeling (+25; beide: p &lt; 0,02), waarschijnlijk gedeeltelijk door een toegenomen gevoeligheid van de galblaas voor CCK (voor beide: p &lt; 0,05 vergeleken met de uitgangsfase). Bezafibraat, in tegenstelling tot visolie, verhoogde de molaire cholesterol-galzuurratio (+40; p ≤ 0,05), terwijl beide behandelingen geen effect hadden op de cholesterolsaturatie-index.Conclusies: De verminderde galblaasmotoriek bij HTG-patiënten lijkt het gevolg te zijn van verminderde gevoeligheid voor CCK, wat kan bijdragen aan het verhoogde risico op galsteenvorming. Bij HTG-patiënten verbetert triglycerideverlagende therapie met visolie of bezafibraat de verminderde galblaasmotoriek zonder nadelig effect op de biliaire cholesterolverzadiging.Objective. To unravel the mechanisms responsible for the increased risk of gall-stone disease in hypertriglyceridaemia (HTG) and to compare the effects of triglyceride-lowering therapy with bezafibrate and fish oil on determinants of cholelithiasis (biliary-lipid composition and gall-bladder motility) in HTG patients. Design. Randomised cross over. Patients and methods. Gall-bladder motility (ultrasonography) was studied postprandially and during infusion of cholecystokinin (CCK). Determinants of cholelithiasis and serum lipids were compared between 9 HTG patients and 10 age, sex and body-mass index matched normolipidaemic controls. The effects of bezafibrate and purified omega-3-oil ('fish oil') in HTG patients were studied. Results. HTG patients showed 14-fold higher serum-triglyceride (TG) levels than controls. Biliary-lipid composition, fasting gall-bladder volumes, and CCK levels did not differ between HTG patients and controls. Gall-bladder emptying was reduced in HTG patients compared with controls during CCK infusion (-22%) as well as in response to a meal (-37%; both p &lt; 0.001). Postprandial CCK levels were significantly higher in HTG patients. Both bezafibrate and fish oil reduced serum TG levels (-68 and -51% versus baseline, respectively; both p &lt; 0.01). Fasting CCK levels were not affected whereas CCK-induced gall-bladder emptying increased during bezafibrate (+29%; p &lt; 0.001) and tended to increase upon fish-oil therapy (+13%; p = 0.07). Postprandial gall-bladder motility improved at least partly with bezafibrate and fish oil (+47 and +25% versus baseline, respectively; both p &lt; 0.02) due to increased gallbladder sensitivity to CCK (both p &lt; 0.05 versus baseline). Bezafibrate but not fish oil increased the molar ratio of cholesterol to bile acids (+40%; p ≤ 0.05), but no effects on the cholesterol-saturation index were seen with either treatment. Conclusions. We suggest that impaired gall-bladder motility occurs in HTG patients due to decreased sensitivity to CCK, which may add to the enhanced risk of gall-stone disease in HTG patients. Triglyceride-lowering therapy by both fish oil and bezafibrate improves gall-bladder dysmotility without adversely affecting biliary-cholesterol saturation.</p