Recurrent symmetrical bendings cause dwarfing in Hydrangea through spatial molecular regulation of xylem cell walls

Environmental prejudices progressively lead to the ban of dwarfing molecules in agriculture, and alternatives are urgently required. Mechanical stimulation (MS) is a promising, eco-friendly, and economical technique, but some responses to mechanical stimulation vary from one plant species to another. Additionally, as more frequent and violent wind episodes are forecasted under global climate change, knowledge of plant responses to stimuli mimicking wind sways is decisive for agriculture. However, little is known about plant mechanosensitive responses after long-term, recurrent MS. Here, the effects of 3-week, recurrent, symmetrical bendings (1 or 12 per day) in Hydrangea macrophylla stems are examined. Bendings repressed internode elongation and leaf area development, whereas the diametrical growth of the basal internode is increased. Responses were dose-dependent, and no desensitization was observed during the 3 weeks of treatment. MS was almost as efficient as daminozide for plant dwarfing, and it improved stem robustness. Histological and molecular responses to MS were spatially monitored and were concordant with ongoing primary or secondary growth in the internodes. Our molecular data provide the first knowledge on the molecular paths controlled by mechanical loads in Hydrangea and revealed for the first time the involvement of XYP1 in thigmomorphogenetic responses. MS still had a transcriptional impact 48 h after the last bending session, promoting the expression of XYP1, FLA11, and CAD1 while repressing the expression of EXP3 and XTH33 homologs in accordance with xylogenesis, cell wall thickening, and lignin deposition in the xylem of basal internodes. In upper elongating internodes, repression of XYP1, CAD1, SAMS1, and CDC23 homologs is correlated with ongoing primary, even though stunted, growth. For producers, our findings highlight the potential of MS as a sustainable and economical option for controlling plant compactness in Hydrangea and show valuable reinforcement of stem strength.

Unraveling the dataset transcriptomic response of Hydrangea macrophylla stem to mechanical stimulation: De novo assembly and functional annotation

A crucial attribute of potted ornamental plants is compactness characterized by well branched plants with rather short stems bearing numerous flowers. To gain plant compactness, producers use plant growth regulators (PGRs), in particular growth retardants during culture. However, due to their negative environmental impacts, growth retardants are progressively withdrawn from the market. As a response, eco-friendly alternative methods to chemicals need to be developed. One method consists in mimicking mechanical stimulation (MS) imposed by wind on plants which causes reduction in stem elongation, an increase in stem diameter and an increase in branching, all contributing to plant compactness. So far, few plant species were studied under MS and little is known on molecular response mechanisms to MS. This first transcriptomic data after MS in Hydrangea macrophylla will contribute unravelling how plants respond to mechanical stimuli. RNAseq data were obtained from total mRNA of stems collected 15 min before MS and 1, 3, 24 and 72 h after MS treatment. RNA from non-MS treated plants were used as control. MS treatment consisted in 12 consecutive bendings (i.e. 6 forth and 6 back) applied at 9 a.m. during 1 h and for a single day. From RNAseq data a de novo assembly of the transcriptome was produced and 78,398 transcripts functionally annotated. These transcriptomic data also contribute to a better knowledge of how outdoor crop respond to the increasing frequency of strong harmful winds under climate change.

Non thermal 2.45 GHz electromagnetic exposure causes rapid changes in Arabidopsis thaliana metabolism

Numerous studies report different types of responses following exposure of plants to high frequency electromagnetic fields (HF-EMF). While this phenomenon is related to tissue heating in animals, the situation is much less straightforward in plants where metabolic changes seem to occur without tissue temperature increase. We have set up an exposure system allowing reliable measurements of tissue heating (using a reflectometric probe and thermal imaging) after a long exposure (30 min) to an electromagnetic field of 2.45 GHz transmitted through a horn antenna (about 100 V m^-1 at the plant level). We did not observe any heating of the tissues, but we detected rapid increases (60 min) in the accumulation of transcripts of stress-related genes (TCH1 and ZAT12 transcription factor) or involved in ROS metabolism (RBOHF and APX1). At the same time, the amounts of hydrogen peroxide and dehydroascorbic acid increased while glutathione (reduced and oxidized forms), ascorbic acid, and lipid peroxidation remained stable. Therefore, our results unambiguously show that molecular and biochemical responses occur rapidly (within 60min) in plants after exposure to an electromagnetic field, in absence of tissue heating.

High Expression of ALTERNATIVE OXIDASE 2 in Latent Axillary Buds Suggests Its Key Role in Quiescence Maintenance in Rosebush

Most vegetative axes remain quiescent as dormant axillary buds until metabolic and hormonal signals, driven by environmental changes, trigger bud outgrowth. While the resumption of growth activity is well documented, the establishment and maintenance of quiescence is comparatively poorly understood, despite its major importance in the adaptation of plants to the seasonal cycle or in the establishment of their shape. Here, using the rosebush Rosa hybrida 'Radrazz' as a plant model, we highlighted that the quiescent state was the consequence of an internal and active energy control of buds, under the influence of hormonal factors previously identified in the bud outgrowth process. We found that the quiescent state in the non-growing vegetative axis of dormant axillary buds displayed a low energy state along with a high expression of the ALTERNATIVE OXIDASE 2 (AOX2) and the accumulation of the corresponding protein. Conversely, AOX2 expression and protein amount strongly decreased during bud burst as energy status shifted to a high state, allowing growth. Since AOX2 can deviate electrons from the cytochrome pathway in the mitochondrial respiratory chain, it could drastically reduce the formation of ATP, which would result in a low energy status unfavorable for growth activities. We provide evidence that the presence/absence of AOX2 in quiescent/growing vegetative axes of buds was under hormonal control and thus may constitute the mechanistic basis of both quiescence and sink strength manifestation, two important aspects of budbreak.

Ascorbate-glutathione pathways mediated by cytokinin regulate H2O2 levels in light-controlled rose bud burst

Rosebush (Rosa "Radrazz") plants are an excellent model to study light control of bud outgrowth since bud outgrowth only arises in the presence of light and never occurs in darkness. Recently, we demonstrated high levels of hydrogen peroxide (H2O2) present in the quiescent axillary buds strongly repress the outgrowth process. In light, the outgrowing process occurred after H2O2 scavenging through the promotion of Ascorbic acid-Glutathione (AsA-GSH)-dependent pathways and the continuous decrease in H2O2 production. Here we showed Respiratory Burst Oxidase Homologs expression decreased in buds during the outgrowth process in light. In continuous darkness, the same decrease was observed although H2O2 remained at high levels in axillary buds, as a consequence of the strong inhibition of AsA-GSH cycle and GSH synthesis preventing the outgrowth process. Cytokinin (CK) application can evoke bud outgrowth in light as well as in continuous darkness. Furthermore, CKs are the initial targets of light in the photocontrol process. We showed CK application to cultured buds in darkness decreases bud H2O2 to a level that is similar to that observed in light. Furthermore, this treatment restores GSH levels and engages bud burst. We treated plants with buthionine sulfoximine, an inhibitor of GSH synthesis, to solve the sequence of events involving H2O2/GSH metabolisms in the photocontrol process. This treatment prevented bud burst, even in the presence of CK, suggesting the sequence of actions starts with the positive CK effect on GSH that in turn stimulates H2O2 scavenging, resulting in initiation of bud outgrowth.

Ascorbate glutathione-dependent H2O2 scavenging is an important process in axillary bud outgrowth in rosebush

BACKGROUND AND AIMS

Branching is an important mechanism of plant shape establishment and the direct consequence of axillary bud outgrowth. Recently, hydrogen peroxide (H2O2) metabolism, known to be involved in plant growth and development, has been proposed to contribute to axillary bud outgrowth. However, the involvement of H2O2 in this process remains unclear.

METHODS

We analysed the content of H2O2 during bud outgrowth and characterized its catabolism, both at the transcriptional level and in terms of its enzymatic activities, using RT-qPCR and spectrophotometric methods, respectively. In addition, we used in vitro culture to characterize the effects of H2O2 application and the reduced glutathione (GSH) synthesis inhibitor l-buthionine sulfoximine (BSO) on bud outgrowth in relation to known molecular markers involved in this process.

KEY RESULTS

Quiescent buds displayed a high content of H2O2 that declined when bud outgrowth was initiated, as the consequence of an increase in the scavenging activity that is associated with glutathione pathways (ascorbate-glutathione cycle and glutathione biosynthesis); catalase did not appear to be implicated. Modification of bud redox state after the application of H2O2 or BSO prevented axillary bud outgrowth by repressing organogenesis and newly formed axis elongation. Hydrogen peroxide also repressed bud outgrowth-associated marker gene expression.

CONCLUSIONS

These results show that high levels of H2O2 in buds that are in a quiescent state prevents bud outgrowth. Induction of ascorbate-glutathione pathway scavenging activities results in a strong decrease in H2O2 content in buds, which finally allows bud outgrowth.

Genetic characterization of Shigatoxigenic and enteropathogenic Escherichia coli O80:H2 from diarrhoeic and septicaemic calves and relatedness to human Shigatoxigenic E. coli O80:H2

AIM

The purpose of this work was to identify and genetically characterize enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC) O80:H2 from diarrhoeic and septicaemic calves in Belgium and to comparing them with human EHEC after whole genome sequencing.

METHODS AND RESULTS

Ten EHEC and 21 EPEC O80 identified by PCR between 2009 and 2018 from faeces, intestinal content and a kidney of diarrhoeic or septicaemic calves were genome sequenced and compared to 19 human EHEC identified between 2008 and 2019. They all belonged to the O80:H2 serotype and ST301, harboured the eaeξ gene, and 23 of the 29 EHEC contained the stx2d gene. Phylogenetically, they were distributed in two major sub-lineages: one comprised a majority of bovine EPEC whereas the second one comprised a majority of stx2d bovine and human EHEC.

CONCLUSIONS

Not only EPEC but also EHEC O80:H2 are present in diarrhoeic and septicaemic calves in Belgium and are genetically related to human EHEC.

SIGNIFICANCE AND IMPACT OF THE STUDY

These findings support the need to assess cattle as potential source of contamination of humans by EHEC O80:H2 and to understand the evolution of bovine and human EHEC and EPEC O80:H2.

Activation of a Metal-Halogen Bond by Halogen Bonding

In recent years, the non-covalent interaction of halogen bonding (XB) has found increasing application in organocatalysis. However, reports of the activation of metal-ligand bonds by XB have so far been limited to a few reactions with elemental iodine or bromine. Herein, we present the activation of metal-halogen bonds by two classes of inert halogen bond donors and the use of the resulting activated complexes in homogenous gold catalysis. The only recently explored class of iodolium derivatives were shown to be effective activators in two test reactions and their activity could be modulated by blocking of the Lewis acidic sites. Bis(benzimidazolium)-based halogen bonding activators provided even more rapid conversion, while the non-iodinated reference compound showed little activity. The role of halogen bonding in the activation of metal-halogen bonds was further investigated by NMR experiments and DFT calculations, which support the mode of activation occurring via halogen bonding.

Methylmercury complexes: Selection of thermodynamic properties and application to the modelling of a column experiment

Complexation with methyl groups produces the most toxic form of mercury, especially because of its capacity to bioconcentrate in living tissues. Understanding and integrating methylation and demethylation processes is of the utmost interest in providing geochemical models relevant for environmental assessment. In a first step, we investigated methylation at equilibrium, by selecting the thermodynamic properties of different complexes that form in the chemical system Hg-SO₃-S-Cl-C-H₂O. The selection included temperature dependencies of the equilibrium constants when available. We also considered adsorption and desorption reactions of both methylated and non-methylated mercury onto mineral surfaces. Then we assessed the kinetics of methylation by comparing a dedicated column experiment with the results of a geochemical model, including testing different methylation and demethylation kinetic rate laws. The column system was a simple medium: silicic sand and iron hydroxides spiked with a mercury nitrate solution. The modelling of methylmercury production with two different rate laws from the literature is bracketing the experimental results. Dissolved mercury, iron and sulfate concentrations were also correctly reproduced. The internal evolution of the column was also correctly modeled, including the precipitation of mackinawite (FeS) and the evolution of dissolved iron. The results validate the conceptual model and underline the capacity of geochemical models to reproduce some processes driven by bacterial activity.

Asparagine and sugars are both required to sustain secondary axis elongation after bud outgrowth in Rosa hybrida

Nitrogen is required for optimal plant growth, especially in young organs such as secondary axes (axes II) after axillary bud outgrowth. Several studies have shown an increase of nitrogen concentration in xylem sap concomitantly with bud outgrowth, but the relation between nitrogen, sugars and plant hormones in axis II still remains unclear. We investigated in Rosa hybrida the involvement of nitrogen nutrition in axis II elongation in relation with sugars and cytokinins using ¹⁵N-labeled nitrate and sugars, amino acids and cytokinin quantifications. Besides, we measured the effect of the exogenous supply of these compounds on axis II elongation using in vitro excised bud culture. We demonstrated that nitrogen in the axis II comes mainly from new root uptake after decapitation. Asparagine, which concentration increases in sap exudates and tissues during axis II elongation, was the sole amino acid able to sustain an efficient elongation in vitro when supplied in combination with sucrose.

French Previously Untreated Patients with Severe Hemophilia A after Exposure to Recombinant Factor VIII : Incidence of Inhibitor and Evaluation of Immune Tolerance

Fifty French previously untreated patients with severe hemophilia A (factor VIII <1%), treated with only one brand of recombinant factor VIII (rFVIII), were evaluated for inhibitor development, assessment of risk factors and outcome of immune tolerance regimen. The median period on study was 32 months (range 9-74) since the first injection of rFVIII. Fourteen patients (28%) developed an inhibitor, four of whom (8%) with a high titer (≥10 BU). All inhibitor patients but one continued to receive rFVIII either for on-demand treatment or for immune tolerance regimen (ITR). Among these patients, inhibitor was transient in 2 (4%), became undetectable in 6 and was still present in 6. The prevalence of inhibitor was 12%. Presence of intron 22 inversion was found to be a risk factor for inhibitor development. Immune tolerance was difficult to achieve in our series despite a follow-up period of 16 to 30 months: immune tolerance was complete in only one out of the 3 patients undergoing low dose ITR and in one out of the 5 patients with high dose ITR.

Effect of the Antioxidants Selenium and Beta-carotene on HIV-related Endothelium Dysfunction

Patients infected with HIV are at increased risk of atherosclerosis, and have evidence of endothelium dysfunction. The hypothesis was tested that HIV-related endothelium dysfunction is related to loss of antioxidants. This was done by the supplementation of the antioxidants selenium and beta-carotene. We supplemented the diet of 10 HIV-sero-positive subjects with 100 μg selenium daily, 11 subjects with 30 mg beta-carotene twice daily while 15 subjects were not supplemented. Plasma was obtained at outset and after a year, and tested by ELISA for endothelial cell, platelet and inflammatory markers.

The non-supplemented patients experienced increases in von Wille-brand factor and soluble thrombomodulin (both p < 0.01). There were no changes in any of the indices in the patients taking selenium or beta-carotene.

Increased von Willebrand factor and soluble thrombomodulin in the non-supplemented patients imply increased damage to the endothelium over the year of the study. Therefore we interpret the lack of increase in the patients taking antioxidants as evidence of the protection of the endothelium by these agents.

Investigation of Iodonium Trifluoroborate Zwitterions as Bifunctional Arene Reagents

The synthesis of a new family of iodonium zwitterions, in which the formal anion is a trifluoroborate moiety, is reported. These reagents present very good stability and have high resistance toward benzyne formation. Their structures were confirmed by X-ray crystallographic analysis and were further investigated using DFT calculations. QTAIM analysis supports an ionic, noncovalent, I⁺···BF₃^- interaction, in accordance with a true zwitterionic nature. Preliminary results of synthetic applications, the arylation of phenolates and trifluoroborate group functionalization, are reported.

New resources for genetic studies in Populus nigra: genome-wide SNP discovery and development of a 12k Infinium array

Whole genome resequencing of 51 Populus nigra (L.) individuals from across Western Europe was performed using Illumina platforms. A total number of 1 878 727 SNPs distributed along the P. nigra reference sequence were identified. The SNP calling accuracy was validated with Sanger sequencing. SNPs were selected within 14 previously identified QTL regions, 2916 expressional candidate genes related to rust resistance, wood properties, water-use efficiency and bud phenology and 1732 genes randomly spread across the genome. Over 10 000 SNPs were selected for the construction of a 12k Infinium Bead-Chip array dedicated to association mapping. The SNP genotyping assay was performed with 888 P. nigra individuals. The genotyping success rate was 91%. Our high success rate was due to the discovery panel design and the stringent parameters applied for SNP calling and selection. In the same set of P. nigra genotypes, linkage disequilibrium throughout the genome decayed on average within 5-7 kb to half of its maximum value. As an application test, ADMIXTURE analysis was performed with a selection of 600 SNPs spread throughout the genome and 706 individuals collected along 12 river basins. The admixture pattern was consistent with genetic diversity revealed by neutral markers and the geographical distribution of the populations. These newly developed SNP resources and genotyping array provide a valuable tool for population genetic studies and identification of QTLs through natural-population based genetic association studies in P. nigra.

Low-amplitude, high-frequency electromagnetic field exposure causes delayed and reduced growth in Rosa hybrida

It is now accepted that plants perceive high-frequency electromagnetic field (HF-EMF). We wondered if the HF-EMF signal is integrated further in planta as a chain of reactions leading to a modification of plant growth. We exposed whole small ligneous plants (rose bush) whose growth could be studied for several weeks. We performed exposures at two different development stages (rooted cuttings bearing an axillary bud and 5-leaf stage plants), using two high frequency (900MHz) field amplitudes (5 and 200Vm(-1)). We achieved a tight control on the experimental conditions using a state-of-the-art stimulation device (Mode Stirred Reverberation Chamber) and specialized culture-chambers. After the exposure, we followed the shoot growth for over a one-month period. We observed no growth modification whatsoever exposure was performed on the 5-leaf stage plants. When the exposure was performed on the rooted cuttings, no growth modification was observed on Axis I (produced from the elongation of the axillary bud). Likewise, no significant modification was noted on Axis II produced at the base of Axis I, that came from pre-formed secondary axillary buds. In contrast, Axis II produced at the top of Axis I, that came from post-formed secondary buds consistently displayed a delayed and significant reduced growth (45%). The measurements of plant energy uptake from HF-EMF in this exposure condition (SAR of 7.2 10(-4)Wkg(-1)) indicated that this biological response is likely not due to thermal effect. These results suggest that exposure to electromagnetic field only affected development of post-formed organs.

Light and nitrogen nutrition regulate apical control in Rosa hybrida L

Apical control is defined as the inhibition of basal axillary bud outgrowth by an upper actively growing axillary axis, whose regulation is poorly understood yet differs markedly from the better-known apical dominance. We studied the regulation of apical control by environmental factors in decapitated Rosa hybrida in order to remove the apical hormonal influence and nutrient sink. In this plant model, all the buds along the main axis have a similar morphology and are able to burst in vitro. We concentrated on the involvement of light intensity and nitrate nutrition on bud break and axillary bud elongation in the primary axis pruned above the fifth leaf of each rose bush. We observed that apical control took place in low light (92 μmol m(-2)s(-1)), where only the 2-apical buds grew out, both in low (0.25 mM) and high (12.25 mM) nitrate. In contrast, in high light (453 μmol m(-2)s(-1)), the apical control only operates in low nitrate while all the buds along the stem grew out when the plant was supplied with a high level of nitrate. We found a decreasing photosynthetic activity from the top to the base of the plant concomitant with a light gradient along the stem. The quantity of sucrose, fructose, glucose and starch are higher in high light conditions in leaves and stem. The expression of the sucrose transporter RhSUC2 was higher in internodes and buds in this lighting condition, suggesting an increased capacity for sucrose transport. We propose that light intensity and nitrogen availability both contribute to the establishment of apical control.

Rose bush leaf and internode expansion dynamics: analysis and development of a model capturing interplant variability

Rose bush architecture, among other factors, such as plant health, determines plant visual quality. The commercial product is the individual plant and interplant variability may be high within a crop. Thus, both mean plant architecture and interplant variability should be studied. Expansion is an important feature of architecture, but it has been little studied at the level of individual organs in rose bushes. We investigated the expansion kinetics of primary shoot organs, to develop a model reproducing the organ expansion of real crops from non-destructive input variables. We took interplant variability in expansion kinetics and the model's ability to simulate this variability into account. Changes in leaflet and internode dimensions over thermal time were recorded for primary shoot expansion, on 83 plants from three crops grown in different climatic conditions and densities. An empirical model was developed, to reproduce organ expansion kinetics for individual plants of a real crop of rose bush primary shoots. Leaflet or internode length was simulated as a logistic function of thermal time. The model was evaluated by cross-validation. We found that differences in leaflet or internode expansion kinetics between phytomer positions and between plants at a given phytomer position were due mostly to large differences in time of organ expansion and expansion rate, rather than differences in expansion duration. Thus, in the model, the parameters linked to expansion duration were predicted by values common to all plants, whereas variability in final size and organ expansion time was captured by input data. The model accurately simulated leaflet and internode expansion for individual plants (RMSEP = 7.3 and 10.2% of final length, respectively). Thus, this study defines the measurements required to simulate expansion and provides the first model simulating organ expansion in rosebush to capture interplant variability.

Successful major and minor surgery using factor VIII inhibitor bypassing activity in patients with haemophilia A and inhibitors

Surgeries are being increasingly performed in patients with haemophilia A and high-titre inhibitors. Optimal bypassing agent regimens need further delineation. Data pertaining to surgeries from 1989 to 2004 at a single centre were retrospectively analysed. Patients received a standardized factor eight inhibitor bypassing activity (FEIBA) dose for both major and minor elective or emergency surgeries. The standard FEIBA dose was 70 U kg(-1) per infusion. FEIBA was infused at 9 and 1 h before and 8 h after operation. Infusions were routinely repeated every 8 h afterward. Haemostatic efficacy was assessed on the basis of blood loss, occurrence of haematoma and transfusion requirements. Seven adult patients underwent a total of 12 operations: 10 major and two minor. Ten procedures were elective. The median cumulative numbers of infusions and days of therapy were 46 and 17, respectively. Cumulative total FEIBA consumption was a median of 3185 U kg(-1). Observed blood losses, haematoma incidence and transfusion requirements were comparable to those expected for noncoagulopathic patients undergoing similar procedures. The only large haematoma occurred after a hip prosthesis operation and resolved under continuing FEIBA treatment. There were no cases of disseminated intravascular coagulation or other thromboembolic complications. FEIBA provides an effective and safe first-line peri- and postoperative haemostatic therapy for patients with haemophilia A and inhibitors, allowing both major and minor operations to be successfully performed.

HLA-associated genetic resistance and susceptibility to type I diabetes in French North Africans and French natives

The distribution of human leukocyte antigen (HLA)-DRB1-DQA1-DQB1 haplotypes was analyzed separately in two distinct French ethnic groups with type I diabetes (T1D), i.e. French North African migrants (n= 64, mean age at diagnosis = 8.25 years) and ancient French natives (n= 60, mean age at diagnosis = 7.42 years). HLA associations were determined by calculating odds ratios (ORs) between patients and two ethnic-matched control populations. Results show highly similar ORs for the conservative DRB1*0301-DQA1*0501-DQB1*0201 haplotype of susceptibility (OR: 3.22 and 3.93 in migrants and natives, respectively) and the DRB1*1501-DQA1*0102-DQB1*0602 haplotype of resistance (OR: 0.05 and 0.03, respectively). In contrast, among the more variable DRB1*04-DQB1*0302 haplotypes of susceptibility, the DRB1*0402 (OR: 3.10 and 32.84) and 0405 (OR: 5.90 and 16.25, respectively) were associated with T1D in migrants and natives, whereas an increase of DRB1*0401, a rare allele in migrants, was significant in natives only. Also, among the DRB1*11-DQA1*0505-DQB1*0301 haplotypes of resistance, the OR observed for DRB1*1104-DQA1*0505-DQB1*0301, common in migrants, was lower (OR: 0.08) than for DRB1*1101-DQA1*0505-DQB1*0301 (OR: 0.32), common in natives. How DRB1*11 subtypes might affect differently the risk conferred by DQA1*0505-DQB1*0301 will be discussed.

Mobilisation of nutrients and transport via the xylem sap in a shrub (Ligustrum ovalifolium) during spring growth: N and C compounds and interactions

In open-field soilless culture there can be great deal of leaching, particularly in rainy springs. Ligneous plants have the capacity to store large quantities of nutrients in perennial organs. Knowledge of the plant's internal nutrient mobilisation during spring to supply growing organs could lead to reduction of fertiliser application. To quantify the fraction of storage mobilisation available for growth of new organs during spring, Ligustrum ovalifolium shrubs were grown for 2 years with or without fertilisation in the second spring. Nitrogen (N) absorption and N and carbon (C) mobilisation from storage were followed during spring growth via the sap quality. A mathematical combination of the sap composition with flow velocity provided the transported quantities of N and C. Nitrogen and C mobilisation towards new shoots took place during all the spring growth from bud break onwards. In unfertilised plants, C was mobilised primarily as sugars (stachyose, mannose and sucrose) and starch. In fertilised plants, the same sugars were transported in the xylem sap, but at lower concentrations. Stachyose concentration was lower in fertilised than in unfertilised plants and decreased during spring growth. Nitrogen was transported in the xylem sap mainly as amino acids in both fertilisation treatments. Glutamine was the predominant form at bud break and during shoot elongation. In fertilised plants, arginine became predominant after shoot elongation, and was related to low C availability. The interactions of N with C are discussed; specifically, insufficient availability of N limits the use of C, more of which is directed to aerial organs by sap flow.

Microsphere entrapped bee-venom phospholipase A2 retains specific IgE binding capacity: a possible use for oral specific immunotherapy

The only specific treatments of allergy are long and exacting desensitization by subcutaneous injections of the allergens. While oral administration of allergens could greatly facilitate these treatments, effective delivery systems are needed to prevent allergen degradation in the gastrointestinal tract and to enable their uptake by Peyer's patches. The potential for bee-venom phospholipase A2 (PLA2) to be used in such oral immunotherapy was tested. For this purpose, PLA2 potential alterations were analysed when encapsulated into poly(D,L-lactide-co-glycolide) microspheres by double emulsion solvent evaporation. It was shown that microencapsulation had only limited effects on the integrity of the entrapped PLA2, which retained its fully specific murine IgE binding capacity. Thus, PLA2 loaded microspheres could represent a potential delivery system for bee venom allergy-specific oral immunotherapy.

Substituted 3-amino and/or 3-aminomethyl-3,4-dihydro-2H-1-benzopyrans: synthesis and biological activity

A series of new 3-amino, 3-aminomethyl-5-alkoxy-3,4-dihydro-2H-1-benzopyran and 5'-alkoxy-3',4'-dihydrospiro-[piperazine-2.3'(2'H)-benzopyran] derivatives was prepared and evaluated for affinity at 5-HT1A, 5-HT2A and D2 receptors. Two of the compounds (1f and 2b) can be considered as potent and selective 5-HT2A ligands. One compound (1g) demonstrated high affinity for 5-HT1A and D2 receptor binding sites and one compound (1d) proved to be a mixed 5-HT1A/5-HT2A ligand.

[Length of stay in maternity wards after normal delivery: diverging point of views]

OBJECTIVES

To compare maternity ward professionals' and patients' views regarding the length of stay in the maternity after a normal delivery and to explore working relationships with ambulatory health professionals.

METHODS

Three surveys

RESULTS

General professional agreement on a minimum of 4 days; few contacts with ambulatory health professionals. One third of the women found their length of stay excessive. Most did not appear to gain new skills after 3 days, nor to encounter major difficulties once they returned to their home.

DISCUSSION

and conclusion. It will be essential to organize effective working relationships between the maternity ward and ambulatory health professionals to ensure appropriate follow-up after an earlier discharge from the hospital, in agreement with the capabilities and expectations of a majority of women.

Three months supplementation of hyperhomocysteinaemic patients with folic acid and vitamin B6 improves biological markers of endothelial dysfunction

Hyperhomocysteinaemia is a risk factor for premature atherosclerosis and venous thromboembolic disease. Supplementation with folic acid and vitamin B6 has been shown to decrease plasma homocysteine but data fail to assess an effect on the progression of vascular disease. We measured plasma homocysteine and two markers of endothelial injury (plasma soluble thrombomodulin and von Willebrand factor) at baseline and after 3 months of treatment with folic acid and vitamin B6. After this treatment there was a significant decrease in fasting soluble thrombomodulin (-15 ng/ml, 95%CI 5-22.2). Von Willebrand factor was significantly raised after methionine load at baseline but did not significantly rise after supplementation.

Endothelial dysfunction during acute methionine load in hyperhomocysteinaemic patients

Hyperhomocysteinaemia has been associated with arterial and venous thrombosis possibly by causing damage to the endothelium. We hypothesised that an oral load in methionine, that increases plasma homocysteine, would also result in an increase in biological markers of endothelial or platelet dysfunction. Then we investigated two groups of patients with arterial or venous occlusive disease: 17 with hyperhomocysteinemia and 12 without hyperhomocysteinemia. We measured in both groups plasma soluble thrombomodulin, von Willebrand factor, P-selectin and tissue factor plasma inhibitor before and 6 hours after a load with 100 mg/kg oral methionine. Methionine load resulted in a significant increase in von Willebrand factor in both groups (P<0.02), suggesting that endothelial dysfunction occurs during the load.