Ageing-induced shrinkage of intervessel pit membranes in xylem of Clematis vitalba modifies its mechanical properties as revealed by atomic force microscopy.

Bordered pit membranes of angiosperm xylem are anisotropic, mesoporous media between neighbouring conduits, with a key role in long distance water transport. Yet, their mechanical properties are poorly understood. Here, we aim to quantify the stiffness of intervessel pit membranes over various growing seasons. By applying an AFM-based indentation technique "Quantitative Imaging" we measured the effective elastic modulus (E effective) of intervessel pit membranes of Clematis vitalba in dependence of size, age, and hydration state. The indentation-deformation behaviour was analysed with a non-linear membrane model, and paired with magnetic resonance imaging to visualise sap-filled and embolised vessels, while geometrical data of bordered pits were obtained using electron microscopy. E effective was transformed to the geometrically independent apparent elastic modulus E apparent and to aspiration pressure P b. The material stiffness (E apparent) of fresh pit membranes was with 57 MPa considerably lower than previously suggested. The estimated pressure for pit membrane aspiration was 2.20+28 MPa. Pit membranes from older growth rings were shrunken, had a higher material stiffness and a lower aspiration pressure than current year ones, suggesting an irreversible, mechanical ageing process. This study provides an experimental-stiffness analysis of hydrated intervessel pit membranes in their native state. The estimated aspiration pressure suggests that membranes are not deflected under normal field conditions. Although absolute values should be interpreted carefully, our data suggest that pit membrane shrinkage implies increasing material stiffness, and highlight the dynamic changes of pit membrane mechanics and their complex, functional behaviour for fluid transport.

Structural gradients and anisotropic hydraulic conductivity in the enigmatic eel traps of carnivorous corkscrew plants (Genlisea spp.).

PREMISE: Among the sophisticated trap types in carnivorous plants, the underground eel traps of corkskrew plants (Genlisea spp., Lentibulariaceae) are probably the least understood in terms of their functional principle. Here, we provide a detailed analysis of structural and hydraulic features of G. hispidula traps, contributing to the ongoing debate on whether these traps can actively generate water streams to promote prey capture. METHODS: Anatomical and hydraulic traits of detached traps, including inner trap diameters, chamber line element, hair length, glandular pattern, and hydraulic conductivity, were investigated quantitatively using light and electron microscopy, x-ray microtomography, and hydraulic measurements. RESULTS: Hydraulic resistivity in the neck of the trap, from the trap mouth toward the vesicle (digestive chamber) was 10 times lower than in the opposite direction. The comparison of measured and theoretical flow rates suggests that the retrorse hairs inside trap necks also provide considerable resistance against movement of matter toward the vesicle. Hairs showed a gradient in length along the neck, with the shortest hairs near the vesicle. Co-occurrence of quadrifid and bifid glands was limited to a small part of the neck, with quadrifids near the vesicle and bifids toward the trap mouth. CONCLUSIONS: The combination of structural gradients with hydraulic anisotropy suggests the trap is a highly fine-tuned system based on likely trade-offs between efficient prey movement in the trap interior toward the vesicle, prey retention, and spatial digestion capacities and is not counter to the generation of water streams.

Standardized and Individualized Parenteral Nutrition Mixtures in a Pediatric Home Parenteral Nutrition Population.

OBJECTIVES: Studies evaluating efficacy or safety of standardized parenteral nutrition (PN) versus individualized PN are lacking. We aimed to assess effects on growth and safety of standardized PN compared with individualized PN in our Home PN group. METHODS: Descriptive cohort study in Dutch children on Home PN, in which standardized PN was compared with individualized PN. Both groups received similar micronutrient-supplementation. Primary outcome was growth over 2 years, secondary outcomes were electrolyte disturbances and biochemical abnormalities. Additionally, patients were matched for age to control for potential confounding characteristics. RESULTS: Fifty patients (50% girls, median age 6.5 years) were included, 16 (32%) received standardized PN mixtures. Age (11 vs 5 years), gestational age (39.2 vs 36.2 weeks) and PN duration (97 vs 39 months) were significantly higher in the group receiving standardized PN (P: ≤0.001; 0.027; 0.013 respectively). The standardized PN group showed an increase in weight-for-age (WFA), compared with a decrease in the individualized PN group (+0.38 SD vs -0.55 SD, P: 0.003). Electrolyte disturbances and biochemical abnormalities did not differ. After matching for age, resulting in comparable groups, no significant differences were demonstrated in WFA, height-for-age, or weight-for-height SD change. CONCLUSIONS: In children with chronic IF, over 2,5 years of age, standardized PN mixtures show a comparable effect on weight, height, and weight for height when compared with individualized PN mixtures. Also, standardized PN mixtures (with added micronutrients) seem noninferior to individualized PN mixtures in terms of electrolyte disturbances and basic biochemical abnormalities. Larger studies are needed to confirm these conclusions. TRIAL REGISTRATION: Academical Medical Center medical ethics committee number W18_079 #18.103.

The Role of a Nutrition Support Team in the Management of Intestinal Failure Patients.

Parenteral nutrition (PN) is a complex and specialized form of nutrition support that has revolutionized the care for both pediatric and adult patients with acute and chronic intestinal failure (IF). This has led to the development of multidisciplinary teams focused on the management of patients receiving PN: nutrition support teams (NSTs). In this review we aim to discuss the historical aspects of IF management and NST development, and the practice, composition, and effectiveness of multidisciplinary care by NSTs in patients with IF. We also discuss the experience of two IF centers as an example of contemporary NSTs at work. An NST usually consists of at least a physician, nurse, dietitian, and pharmacist. Multidisciplinary care by an NST leads to fewer complications including infection and electrolyte disturbances, and better survival for patients receiving short- and long-term PN. Furthermore, it leads to a decrease in inappropriate prescriptions of short-term PN leading to significant cost reduction. Complex care for patients receiving PN necessitates close collaboration between team members and NSTs from other centers to optimize safety and effectiveness of PN use.

Phytostabilization of Pb and Cd polluted soils using Helianthus petiolaris as pioneer aromatic plant species.

The area of soils polluted with heavy metals is increasing due to industrialization and globalization. Aromatic plant species can be a suitable alternative way for agricultural valorization and phytomanagement of such soils by the commercialization of essential oils avoiding risks for the food chain. The potential of growing Helianthus petiolaris in heavy metal polluted soils was assessed in pot experiments using spiked soils and soils from a shooting range. In terms of phytostabilization, H. petiolaris could grow in soils containing 1000 mg/kg Pb2+, 50 mg/kg Cd2+, accumulating more than three times the soil Cd content in the aerial parts and translocating significant amounts of Pb to the aerial parts when growing in soils polluted with up to 500 mg/kg Pb. When phytostabilization is considered, phytotoxicity of heavy metals strongly depends on the rhizospheric microbial communities, either by mitigating trace element phytotoxicity or promoting plant growth via phytohormone production. So, the effects of heavy metals on the diversity of the rhizospheric bacterial community were assessed using DNA-fingerprinting.

Health-related quality of life, anxiety, depression and distress of mothers and fathers of children on Home parenteral nutrition.

BACKGROUND & AIMS: Parents of children with intestinal failure, dependent on Home Parenteral Nutrition (HPN), may experience psychosocial problems due to the illness and intensive treatment of their child. Literature concerning psychosocial problems is scarce. Therefore, we aimed to investigate Health-Related Quality of Life (HRQOL), levels of anxiety, depression, distress and everyday problems of these mothers and fathers. METHODS: A multicenter study was conducted among 37 mothers and 25 fathers of 37 children on HPN (response-rate 37/49 = 76%, mean age children = 5.1 years, SD = 4.6). Parents completed three questionnaires to measure different outcomes on the KLIK website (www.hetklikt.nu): the TNO-AZL QOL Questionnaire (TAAQOL) to measure HRQOL, the Hospital Anxiety and Depression Scale (HADS) to measure anxiety and depression, and the Distress Thermometer for Parents (DT-P) to measure distress. Scores were compared to Dutch reference mothers and fathers using Mann-Whitney U-tests. RESULTS: No differences were found in HRQOL, measured by the TAAQOL, between HPN parents compared to the reference groups, except for the subscale 'depressive emotions' for mothers (p = .01) and 'daily activities' for fathers (p = .04). HPN mothers reported higher levels of depression compared to reference mothers (p = .001). In addition, HPN mothers and fathers reported higher levels of distress than reference mothers (p = .001) and fathers (p = .03). HPN mothers reported significantly more problems in the practical, emotional, cognitive and parenting domains, fathers in the social, emotional and parenting domains. CONCLUSIONS: On HRQOL, anxiety and depression, HPN parents generally did not show much differences compared to reference parents. However, when asked about parental distress and everyday problems, HPN treatment of their child seems highly stressful for some parents and influences daily functioning. Therefore, structural screening for parental psychosocial problems in clinical practice, e.g. using the DT-P, is necessary in order to improve the well-being of both these parents and their children dependent on HPN.

[Undernourished in hospital]. / Ondervoed in het ziekenhuis.

Patients with a positive undernutrition screening score stay in hospital 1.4 days longer, with more associated complications and costs. A paper elsewhere in this journal describes the implementation of a novel in-hospital meal service resulting in improved protein and energy intake. Patient satisfaction was maintained and to some extent improved. However, the paper shows the difficulty of improving food intake in hospitalized patients. This may be due to factors such as illness-induced anorexia, poor nurse and physician nutritional awareness, and lack of a clear financial incentive. Despite substantial improvement, only 24% of patients had an adequate protein intake. Optimal nutrition should be inextricably associated with care, education and research. Moreover, achieving optimal nutrition needs continuous involvement from nutritional assistants, dieticians, nurses and physicians as well as an optimal in-hospital meal service. The road to optimal nutrition in underfed patients is still long in a world where overfeeding lies at the base of many healthcare problems.

Carbon nitrides: synthesis and characterization of a new class of functional materials.

Carbon nitride compounds with high N : C ratios and graphitic to polymeric structures are being investigated as potential next-generation materials for incorporation in devices for energy conversion and storage as well as for optoelectronic and catalysis applications. The materials are built from C- and N-containing heterocycles with heptazine or triazine rings linked via sp2-bonded N atoms (N(C)3 units) or -NH- groups. The electronic, chemical and optical functionalities are determined by the nature of the local to extended structures as well as the chemical composition of the materials. Because of their typically amorphous to nanocrystalline nature and variable composition, significant challenges remain to fully assess and calibrate the structure-functionality relationships among carbon nitride materials. It is also important to devise a useful and consistent approach to naming the different classes of carbon nitride compounds that accurately describes their chemical and structural characteristics related to their functional performance. Here we evaluate the current state of understanding to highlight key issues in these areas and point out new directions in their development as advanced technological materials.

Nutrition and the circadian timing system.

Life on earth has evolved under the daily rhythm of light and dark. Consequently, most creatures experience a daily rhythm in food availability. In this review, we first introduce the mammalian circadian timing system, consisting of a central clock in the suprachiasmatic nucleus (SCN) and peripheral clocks in various metabolic tissues including liver, pancreas, and intestine. We describe how peripheral clocks are synchronized by the SCN and metabolic signals. Second, we review the influence of the circadian timing system on food intake behavior, activity of the gastrointestinal system, and several aspects of glucose and lipid metabolism. Third, the circadian control of digestion and metabolism may have important implications for several aspects of food intake in humans. Therefore, we review the human literature on health aspects of meal timing, meal frequency, and breakfast consumption, and we describe the potential implications of the clock system for the timing of enteral tube feeding and parenteral nutrition. Finally, we explore the connection between type 2 diabetes and the circadian timing system. Although the past decade has provided exciting knowledge about the reciprocal relation between biological clocks and feeding/energy metabolism, future research is necessary to further elucidate this fascinating relationship in order to improve human health.

Dissemination of an evidence-based program to reduce fear of falling, South Carolina, 2006-2009.

INTRODUCTION: Falls among older adults are a serious public health issue, and fear of falling can limit mobility, which in turn increases fall risk. A Matter of Balance/Volunteer Lay Leader Model is an evidence-based program designed to address fear of falling. The objective of this study was to describe implementation, dissemination, and outcomes of this program in 3 regions of South Carolina with a predominantly African American and largely underserved population. METHODS: We developed partnerships throughout the state, organized master and lay leader trainings, and documented numbers of lay leaders, programs offered, demographic characteristics of participants, program fidelity, and attendance. Outcome measures were self-reported confidence to prevent and manage falls and a quantitative measure of functional mobility. Both measures were assessed at baseline and after program completion. RESULTS: Older adults (N = 235) attended 18 classes at 16 sites. Barriers to implementation were program teams' limited familiarity with the concept of evidence-based programs and the importance of adhering to program content. Facilitators were state-level leadership and a history of state, regional, and local groups collaborating successfully on other projects. Outcomes indicated greater confidence in managing falls and carrying out activities of daily living. Mobility improved significantly, suggesting a reduced risk for falls. CONCLUSION: Evidence-based programs such as A Matter of Balance/Volunteer Lay Leader Model can be successfully disseminated in underserved areas. Outcomes indicate that participation in fall prevention programs can benefit groups of predominantly African American older adults.

"MY PKU": increasing self-management in patients with phenylketonuria. A randomized controlled trial.

BACKGROUND: Phenylketonuria (PKU) is an autosomal recessive disorder of phenylalanine metabolism. The inability to convert phenylalanine (Phe) into tyrosine causes Phe to accumulate in the body. Adherence to a protein restricted diet, resulting in reduced Phe levels, is essential to prevent cognitive decline. Frequent evaluation of plasma Phe levels and, if necessary, adjustment of the diet are the mainstay of treatment. We aimed to assess whether increased self-management of PKU patients and/or their parents is feasible and safe, by providing direct online access to blood Phe values without immediate professional guidance. METHODS: Thirty-eight patients aged ≥ 1 year participated in a 10 month randomized controlled trial. Patients were randomized into a study group (1) or a control group (2). Group 2 continued the usual procedure: a phone call or e-mail by a dietician in case of a deviant Phe value. Group 1 was given a personal "My PKU" web page with a graph of their recent and previous Phe values, online general information about the dietary treatment and the Dutch PKU follow-up guidelines, and a message-box to contact their dietician if necessary. Phe values were provided on "My PKU" without advice. Outcome measures were: differences in mean Phe value, percentage of values above the recommended range and Phe sample frequency, between a 10-month pre-study period and the study period in each group, and between the groups in both periods. Furthermore we assessed satisfaction of patients and/or parents with the 'My PKU' procedure of online availability. RESULTS: There were no significant differences in mean Phe value, percentage of values above recommended range or in frequency of blood spot sampling for Phe determination between the pre-study period and the study period in each group, nor between the 2 groups during the periods. All patients and/or parents expressed a high level of satisfaction with the new way of disease management. CONCLUSIONS: Increased self-management in PKU by providing patients and/or parents their Phe values without advice is feasible and safe and is highly appreciated. TRIAL REGISTRATION: The trial was registered with The Netherlands National Trial Register (NTR #1171) before recruitment of patients.

Intermittent fasting does not affect whole-body glucose, lipid, or protein metabolism.

BACKGROUND: Intermittent fasting (IF) was shown to increase whole-body insulin sensitivity, but it is uncertain whether IF selectively influences intermediary metabolism. Such selectivity might be advantageous when adapting to periods of food abundance and food shortage. OBJECTIVE: The objective was to assess effects of IF on intermediary metabolism and energy expenditure. DESIGN: Glucose, glycerol, and valine fluxes were measured after 2 wk of IF and a standard diet (SD) in 8 lean healthy volunteers in a crossover design, in the basal state and during a 2-step hyperinsulinemic euglycemic clamp, with assessment of energy expenditure and phosphorylation of muscle protein kinase B (AKT), glycogen synthase kinase (GSK), and mammalian target of rapamycine (mTOR). We hypothesized that IF selectively increases peripheral glucose uptake and lowers proteolysis, thereby protecting protein stores. RESULTS: No differences in body weight were observed between the IF and SD groups. Peripheral glucose uptake and hepatic insulin sensitivity during the clamp did not significantly differ between the IF and SD groups. Likewise, lipolysis and proteolysis were not different between the IF and SD groups. IF decreased resting energy expenditure. IF had no effect on the phosphorylation of AKT but significantly increased the phosphorylation of glycogen synthase kinase. Phosphorylation of mTOR was significantly lower after IF than after the SD. CONCLUSIONS: IF does not affect whole-body glucose, lipid, or protein metabolism in healthy lean men despite changes in muscle phosphorylation of GSK and mTOR. The decrease in resting energy expenditure after IF indicates the possibility of an increase in weight during IF when caloric intake is not adjusted. This study was registered at www.trialregister.nl as NTR1841.

Evaluation of 6 years use of sodium hydroxide solution to clear partially occluded central venous catheters.

BACKGROUND & AIMS: Central venous catheter occlusion is a frequently occurring complication during home parenteral nutrition (HPN). The aim of the study was to investigate the effectiveness of sodium hydroxide (NaOH) administration to clear an occluded central venous catheter especially in HPN. METHOD: Retrospective study to the use of NaOH in partially occluded central venous catheters. About 45 patients with HPN treated in the Academic Medical Center of the University of Amsterdam (AMC) were included in this study between January 1997 and April 2003. Excluded from the study were patients under the age of 18 at the start of HPN and/or patients who use parenteral nutrition for less than 3 months. Partial catheter occlusion was defined as a spontaneous flow less than 60 drops/min. RESULTS: In total, 130 occlusions were registered in 29 HPN patients. The other 16 HPN patients did not report any occlusion. The incidence of occlusions in fat containing total parenteral nutrition (TPN) was 1 occlusion in 167 feeding days. TPN without fat showed only one occlusion (incidence 1 in 7126 feeding days). The use of a lipid emulsion proved an important risk factor for catheter occlusion in this study (P<0.05, RR=43). Ninety-five central venous catheter occlusions were treated with NaOH 0.1M. The remaining occlusions were total or mechanical occlusions making NaOH treatment impossible. In 73 out of 95 partial occlusions treatment with NaOH was effective (P<0.05). Using NaOH extended the use of 32 catheters (range 7-1592 days, mean 328). Twenty-one out of 32 catheters could be used for more than 3 months after using NaOH (P<0.05). CONCLUSION: We conclude that perfusion of a partial occluded central venous catheter (defined as 25-60 drops/min) used for parenteral nutrition with 0.1N NaOH is safe and shows a significant long term improvement in catheter care, by preventing total occlusion and operative removal.

GABA(B) receptor-mediated modulation of cutaneous input at the cuneate nucleus in anesthetized cats.

This study examined the modulatory influence exerted by GABA(B) receptors on the transmission of cutaneous afferent input to cuneate nucleus neurons in anesthetized cats. Electrical stimulation at the center of a receptive field activated cuneate nucleus cells at latencies of < or = 7 ms whereas stimulation at neighboring sites (receptive field edge) increased the response latency. Extracellular recording combined with microiontophoresis demonstrated that GABA(B) receptors are tonically active. Blockade of GABA(B) receptors prolonged sensory-evoked response durations and decreased times of occurrence of successive bursts whereas the agonist baclofen suppressed both these effects. Ejection of baclofen delayed the evoked response from the receptive field edge with respect to the receptive field center response and inhibited responses from the receptive field edge more effectively than responses from the receptive field center. From these results it is concluded that activation of GABA(B) receptors precludes cuneate cells from reaching firing threshold when afferent inputs are weak, spatially modulate cuneate nucleus excitability, play a major role in temporal pattern of discharges, and shape cutaneous receptive fields.

A computational modelling study of oxygen vacancies at LaCoO3 perovskite surfaces.

Atomistic computational modelling of the surface structure of the catalytically-active perovskite LaCoO(3) has been undertaken in order to develop better models of the processes involved during catalytic oxidation processes. In particular, the energetics of creating oxygen ion vacancies at the surface have been investigated for the three low index faces (100), (110) and (111). Two mechanisms for vacancy creation have been considered involving dopant Sr(2+) cations at the La(3+) site and reduction of Co(3+) to Co(2+). For both mechanisms, there is a general tendency that the smaller the cation defect separation, the lower the energy of the cluster, as would be expected from simple electrostatic considerations. In addition, there are clear indications that oxygen vacancies are more easily created at the surface than in the bulk. The results also confirm that the presence of defects strongly influences crystal morphology and surface chemistry. The importance of individual crystal surfaces in catalysis is discussed in terms of the energetics for the creation of oxygen vacancies.

Short-term protein intake and stimulation of protein synthesis in stunted children with cystic fibrosis.

BACKGROUND: Stunted children with cystic fibrosis (CF) have less net protein anabolism than do children without CF, and the result is retarded growth in the CF patients. It is not known whether protein intake above that recommended by the Cystic Fibrosis Foundation would further stimulate whole-body protein synthesis. OBJECTIVE: We studied the effects of 3 amounts of protein intake on whole-body protein synthesis and breakdown by using isotopic infusion of [1-(13)C]valine and [(15)N(2)]urea in children with stable CF who required tube feeding. DESIGN: In 8 pediatric CF patients, we administered 3 randomly allocated isocaloric diets with normal (NP), intermediate (IP), and high (HP) amounts of protein (1.5, 3, and 5 g . kg(-1) . d(-1), respectively) by continuous drip feeding during a 4-d period at 6-wk intervals. Each patient acted as his or her own control. On the fourth day of feeding, whole-body protein synthesis and breakdown were measured. RESULTS: Protein synthesis was significantly higher in the HP group (x +/- SEM: 1.78 +/- 0.07 micromol . kg(-1) . min(-1)) than in the IP (1.57 +/- 0.08 micromol . kg(-1) . min(-1); P=0.001) and NP (1.37 +/- 0.07 micromol . kg(-1) . min(-1); P < 0.001) groups. There were no significant differences in protein breakdown. Net retention of nitrogen was significantly higher in the HP group (12.93 +/- 1.42 micromol . kg(-1) . min(-1)) than in the IP (7.61 +/- 1.40 micromol . kg(-1) . min(-1); P=0.01) and HP (2.48 +/- 0.20 micromol . kg(-1) . min(-1); P < 0.001) groups. CONCLUSION: In stunted children with CF requiring tube feeding, the highest stimulation of whole-body protein synthesis was achieved with a short-term dietary protein intake of 5 g . kg(-1) . d(-1).

Single-unit responses of serotonergic medullary and pontine raphe neurons to environmental cooling in freely moving cats.

Brain serotonin has long been implicated in the regulation of body temperature, although its precise role is not completely understood. The present study examined the effects of environmental cooling (4-8 degrees C for 2 or 4h) on the single-unit activity of serotonergic neurons recorded in the medullary raphe nuclei obscurus and pallidus and in the pontine dorsal raphe nucleus of freely moving cats. These neuronal groups have primarily descending projections to the spinal cord and ascending projections to the forebrain, respectively. Cold exposure induced shivering and piloerection, but no appreciable changes in core temperature. Of the medullary serotonergic cells studied (n=14), seven were activated and seven were unresponsive to cold exposure. For the responsive cells, the mean increase and peak effect in unit activity relative to baseline were 31% and 46%, respectively. Of the seven cold-responsive cells, the activity of four was monitored when the animals were transferred back to room temperature (23 degrees C). Within 15-30 min, the activity of these cells returned to baseline. In contrast, none of the dorsal raphe nucleus cells studied (n=14) displayed a significant change in neuronal activity during cold exposure, suggesting that these neurons do not receive afferent input from cold-sensitive cutaneous receptors or participate in thermoregulatory responses evoked by low ambient temperatures.Overall, these results suggest that a subset of medullary serotonergic neurons play a role in physiological mechanisms underlying cold defense (e.g. increases in motor output and/or autonomic outflow). On the other hand, the lack of responsiveness of serotonergic dorsal raphe nucleus neurons to cold exposure does not support a specific role for these cells in thermoregulation.

[Raynaud's phenomenon. Practical considerations on the forms secondary to immunomediated systemic diseases]. / Fenomeno di Raynaud. Considerazioni pratiche sulle forme secondarie a malattie sistemiche immunomediate.

Raynaud's phenomenon is a frequent asphyxial vascular syndrome interesting the 4% of general population. In most of cases it is a functional problem (Raynaud's disease). Less frequently it has an organic cause (Raynaud's syndrome). The pathogenesis of primitive Raynaud's phenomenon remains an enigma. In secondary Raynaud phenomenon the attacks of vasospasm can be explained by the physiopathologic events characterizing the underlying disease. For example, multiple cytokines, transforming grow factor beta, serum immunocomplexes are of great importance in the contest of connective diseases. Clinical examination, some usual laboratory and roentgenographic investigations and nailfold capillary microscopy are of particular importance in orientating the diagnosis.