Dynamics and drivers of mycorrhizal fungi after glacier retreat

The development of terrestrial ecosystems depends greatly on plant mutualists such as mycorrhizal fungi. The global retreat of glaciers exposes nutrient-poor substrates in extreme environments and provides a unique opportunity to study early successions of mycorrhizal fungi by assessing their dynamics and drivers. We combined environmental DNA metabarcoding and measurements of local conditions to assess the succession of mycorrhizal communities during soil development in 46 glacier forelands around the globe, testing whether dynamics and drivers differ between mycorrhizal types. Mycorrhizal fungi colonized deglaciated areas very quickly (< 10 yr), with arbuscular mycorrhizal fungi tending to become more diverse through time compared to ectomycorrhizal fungi. Both alpha- and beta-diversity of arbuscular mycorrhizal fungi were significantly related to time since glacier retreat and plant communities, while microclimate and primary productivity were more important for ectomycorrhizal fungi. The richness and composition of mycorrhizal communities were also significantly explained by soil chemistry, highlighting the importance of microhabitat for community dynamics. The acceleration of ice melt and the modifications of microclimate forecasted by climate change scenarios are expected to impact the diversity of mycorrhizal partners. These changes could alter the interactions underlying biotic colonization and belowground-aboveground linkages, with multifaceted impacts on soil development and associated ecological processes.

In silico assessment of 18S rDNA metabarcoding markers for the characterization of nematode communities

Nematodes are keystone actors of soil, freshwater and marine ecosystems, but the complexity of morphological identification has limited broad-scale monitoring of nematode biodiversity. DNA metabarcoding is increasingly used to assess nematode diversity but requires universal primers with high taxonomic coverage and high taxonomic resolution. Several primers have been proposed for the metabarcoding of nematode diversity, many of which target the 18S rRNA gene. In silico analyses have a great potential to assess key parameters of primers, including taxonomic coverage, resolution and specificity. Based on a recently-available reference database, we tested in silico the performance of fourteen commonly used and one newly optimized primer for nematode metabarcoding. Most primers showed very good coverage, amplifying most of the sequences in the reference database, while four markers showed limited coverage. All primers showed good taxonomic resolution. Resolution was particularly good if the aim was the identification of higher-level taxa, such as genera or families. Overall, species-level resolution was higher for primers amplifying long fragments. None of the primers was highly specific for nematodes as, despite some variation, they all amplified a large number of other eukaryotes. Differences in performance across primers highlight the complexity of the choice of markers appropriate for the metabarcoding of nematodes, which depends on a trade-off between taxonomic resolution and the length of amplified fragments. Our in silico analyses provide new insights for the identification of the most appropriate primers, depending on the study goals and the origin of DNA samples. This represents an essential step to design and optimize metabarcoding studies assessing nematode diversity.

The importance of species addition 'versus' replacement varies over succession in plant communities after glacier retreat

The mechanisms underlying plant succession remain highly debated. Due to the local scope of most studies, we lack a global quantification of the relative importance of species addition 'versus' replacement. We assessed the role of these processes in the variation (β-diversity) of plant communities colonizing the forelands of 46 retreating glaciers worldwide, using both environmental DNA and traditional surveys. Our findings indicate that addition and replacement concur in determining community changes in deglaciated sites, but their relative importance varied over time. Taxa addition dominated immediately after glacier retreat, as expected in harsh environments, while replacement became more important for late-successional communities. These changes were aligned with total β-diversity changes, which were more pronounced between early-successional communities than between late-successional communities (>50 yr since glacier retreat). Despite the complexity of community assembly during plant succession, the observed global pattern suggests a generalized shift from the dominance of facilitation and/or stochastic processes in early-successional communities to a predominance of competition later on.

Local climate modulates the development of soil nematode communities after glacier retreat

The worldwide retreat of glaciers is causing a faster than ever increase in ice-free areas that are leading to the emergence of new ecosystems. Understanding the dynamics of these environments is critical to predicting the consequences of climate change on mountains and at high latitudes. Climatic differences between regions of the world could modulate the emergence of biodiversity and functionality after glacier retreat, yet global tests of this hypothesis are lacking. Nematodes are the most abundant soil animals, with keystone roles in ecosystem functioning, but the lack of global-scale studies limits our understanding of how the taxonomic and functional diversity of nematodes changes during the colonization of proglacial landscapes. We used environmental DNA metabarcoding to characterize nematode communities of 48 glacier forelands from five continents. We assessed how different facets of biodiversity change with the age of deglaciated terrains and tested the hypothesis that colonization patterns are different across forelands with different climatic conditions. Nematodes colonized ice-free areas almost immediately. Both taxonomic and functional richness quickly increased over time, but the increase in nematode diversity was modulated by climate, so that colonization started earlier in forelands with mild summer temperatures. Colder forelands initially hosted poor communities, but the colonization rate then accelerated, eventually leveling biodiversity differences between climatic regimes in the long term. Immediately after glacier retreat, communities were dominated by colonizer taxa with short generation time and r-ecological strategy but community composition shifted through time, with increased frequency of more persister taxa with K-ecological strategy. These changes mostly occurred through the addition of new traits instead of their replacement during succession. The effects of local climate on nematode colonization led to heterogeneous but predictable patterns around the world that likely affect soil communities and overall ecosystem development.

Metabarcoding data reveal vertical multitaxa variation in topsoil communities during the colonization of deglaciated forelands

Ice-free areas are expanding worldwide due to dramatic glacier shrinkage and are undergoing rapid colonization by multiple lifeforms, thus representing key environments to study ecosystem development. It has been proposed that the colonization dynamics of deglaciated terrains is different between surface and deep soils but that the heterogeneity between communities inhabiting surface and deep soils decreases through time. Nevertheless, tests of this hypothesis remain scarce, and it is unclear whether patterns are consistent among different taxonomic groups. Here, we used environmental DNA metabarcoding to test whether community diversity and composition of six groups (Eukaryota, Bacteria, Mycota, Collembola, Insecta, and Oligochaeta) differ between the surface (0-5 cm) and deeper (7.5-20 cm) soil at different stages of development and across five Alpine glaciers. Taxonomic diversity increased with time since glacier retreat and with soil evolution. The pattern was consistent across groups and soil depths. For Eukaryota and Mycota, alpha-diversity was highest at the surface. Time since glacier retreat explained more variation of community composition than depth. Beta-diversity between surface and deep layers decreased with time since glacier retreat, supporting the hypothesis that the first 20 cm of soil tends to homogenize through time. Several molecular operational taxonomic units of bacteria and fungi were significant indicators of specific depths and/or soil development stages, confirming the strong functional variation of microbial communities through time and depth. The complexity of community patterns highlights the importance of integrating information from multiple taxonomic groups to unravel community variation in response to ongoing global changes.

Feasibility and efficacy of a multidisciplinary palliative approach in patients with advanced interstitial lung disease. A pilot randomised controlled trial

INTRODUCTION AND OBJECTIVES

Interstitial lung diseases (ILDs) encompass a heterogeneous group of parenchymal lung disorders which have a significant burden on quality of life and exercise. The primary purpose of this randomised pilot trial performed in advanced ILD was to determine the feasibility and efficacy of a multidisciplinary palliative care approach (including physiotherapist, psychologist, pulmonologists, and palliative care doctors) to relieve patients' symptoms of dyspnoea, depression measured with the Center for Epidemiological Studies-Depression (CES-D) scale and quality-of-life (QoL) at 6 and 12 months.

MATHERIALS AND METHODS

Fifty patients with confirmed interstitial lung disease at computed tomography (CT) scan and advanced disease were enrolled at our clinic. Patients were randomised to usual care group vs intervention group; in the intervention group, patients were scheduled to meet a physiotherapist, a psychologist, a palliative care doctor, and a pulmonologist specialized in ILD care. Data on dyspnoea, cough, quality of life and depression were recorded; patients in the intervention group were also tested to assess lower body flexibility and strength.

RESULTS

Both groups showed a worsening in dyspnoea during the time course of the trial, but the Borg scale was less in the intervention group at 6 and 12 months. A similar trend was observed also for the CES-D scale. No differences were observed for the other scales.

CONCLUSIONS

A multi-disciplinary palliative care intervention in patients with advanced fibrosing interstitial lung disease is feasible and effective.

TRIAL REGISTRATION

NCT02929966 on ClinGovTrial.

Optimal sequence similarity thresholds for clustering of molecular operational taxonomic units in DNA metabarcoding studies

Clustering approaches are pivotal to handle the many sequence variants obtained in DNA metabarcoding data sets, and therefore they have become a key step of metabarcoding analysis pipelines. Clustering often relies on a sequence similarity threshold to gather sequences into molecular operational taxonomic units (MOTUs), each of which ideally represents a homogeneous taxonomic entity (e.g., a species or a genus). However, the choice of the clustering threshold is rarely justified, and its impact on MOTU over-splitting or over-merging even less tested. Here, we evaluated clustering threshold values for several metabarcoding markers under different criteria: limitation of MOTU over-merging, limitation of MOTU over-splitting, and trade-off between over-merging and over-splitting. We extracted sequences from a public database for nine markers, ranging from generalist markers targeting Bacteria or Eukaryota, to more specific markers targeting a class or a subclass (e.g., Insecta, Oligochaeta). Based on the distributions of pairwise sequence similarities within species and within genera, and on the rates of over-splitting and over-merging across different clustering thresholds, we were able to propose threshold values minimizing the risk of over-splitting, that of over-merging, or offering a trade-off between the two risks. For generalist markers, high similarity thresholds (0.96-0.99) are generally appropriate, while more specific markers require lower values (0.85-0.96). These results do not support the use of a fixed clustering threshold. Instead, we advocate careful examination of the most appropriate threshold based on the research objectives, the potential costs of over-splitting and over-merging, and the features of the studied markers.

Environmental DNA of insects and springtails from caves reveals complex processes of eDNA transfer in soils

Subterranean environments host a substantial amount of biodiversity, however assessing the distribution of species living underground is still extremely challenging. Environmental DNA (eDNA) metabarcoding is a powerful tool to estimate biodiversity in poorly known environments and has excellent performance for soil organisms. Here, we tested 1) whether eDNA metabarcoding from cave soils/sediments allows to successfully detect springtails (Hexapoda: Collembola) and insects (Hexapoda: Insecta); 2) whether eDNA mostly represents autochthonous (cave-dwelling) organisms or it also incorporates information from species living in surface environments; 3) whether eDNA detection probability changes across taxa with different ecology. Environmental DNA metabarcoding analyses detected a large number of Molecular Operational Taxonomic Units (MOTUs) for both insects and springtails. For springtails, detection probability was high, with a substantial proportion of hypogean species, suggesting that eDNA provides good information on the distribution of these organisms in caves. Conversely, for insects most of MOTUs represented taxa living outside caves, and the majority of them represented taxa/organisms living in freshwater environments (Ephemeroptera, Plecoptera and Trichoptera). The eDNA of freshwater insects was particularly abundant in deep sectors of caves, far from the entrance. Furthermore, average detection probability of insects was significantly lower than the one of springtails. This suggests that cave soils/sediments act as "conveyer belts of biodiversity information", possibly because percolating water lead to the accumulation of eDNA of organisms living in nearby areas. Cave soils hold a complex mix of autochthonous and allochthonous eDNA. eDNA provided unprecedented information on the understudied subterranean cave organisms; analyses of detection probability and occupancy can help teasing apart local eDNA from the eDNA representing spatially-integrated biodiversity for whole landscape.

Dynamics of Ecological Communities Following Current Retreat of Glaciers

Glaciers are retreating globally, and the resulting ice-free areas provide an experimental system for understanding species colonization patterns, community formation, and dynamics. The last several years have seen crucial advances in our understanding of biotic colonization after glacier retreats, resulting from the integration of methodological innovations and ecological theories. Recent empirical studies have demonstrated how multiple factors can speed up or slow down the velocity of colonization and have helped scientists develop theoretical models that describe spatiotemporalchanges in community structure. There is a growing awareness of how different processes (e.g., time since glacier retreat, onset or interruption of surface processes, abiotic factors, dispersal, biotic interactions) interact to shape community formation and, ultimately, their functional structure through succession. Here, we examine how these studies address key theoretical questions about community dynamics and show how classical approaches are increasingly being combined with environmental DNA metabarcoding and functional trait analysis to document the formation of multitrophic communities, revolutionizing our understanding of the biotic processes that occur following glacier retreat.

Effects of soil preservation for biodiversity monitoring using environmental DNA

Environmental DNA (eDNA) metabarcoding is becoming a key tool for biodiversity monitoring over large geographical or taxonomic scales and for elusive taxa such as soil organisms. Increasing sample sizes and interest in remote or extreme areas often require the preservation of soil samples and thus deviations from optimal standardized protocols. However, we still ignore the impact of different methods of soil sample preservation on the results of metabarcoding studies and there is no guideline for best practices so far. Here, we assessed the impact of four methods of soil sample preservation that can be conveniently used also in metabarcoding studies targeting remote or difficult to access areas. Tested methods include: preservation at room temperature for 6 hr, preservation at 4°C for 3 days, desiccation immediately after sampling and preservation for 21 days, and desiccation after 6 hr at room temperature and preservation for 21 days. For each preservation method, we benchmarked resulting estimates of taxon diversity and community composition of three different taxonomic groups (bacteria, fungi and eukaryotes) in three different habitats (forest, river bank and grassland) against results obtained under ideal conditions (i.e., extraction of eDNA immediately after sampling). Overall, the different preservation methods only marginally impaired results and only under certain conditions. When rare taxa were considered, we detected small but significant changes in molecular operational taxonomic units (MOTU) richness of bacteria, fungi and eukaryotes across treatments, but MOTU richness was similar across preservation methods if rare taxa were not considered. All the approaches were able to identify differences in community structure among habitats, and the communities retrieved using the different preservation conditions were extremely similar. We propose guidelines on the selection of the optimal soil sample preservation conditions for metabarcoding studies, depending on the practical constraints, costs and ultimate research goals.

Risk Management in nursing homes: an Italian experience in 2019

Background

The ageing of the European population leads to an increasing demand for Long-Term Care services. The security and well-being of the elderly population hosted in nursing homes (NHs) needs an effective Risk Management policy, officially sanctioned in Italy by the so-called “Legge Gelli” n.24 (March 8th, 2017) and the Directive 2011/24/EU on the application of patients' rights in cross-border healthcare. In order to verify the effective application of common “best practices” in terms of Risk Management in NHs, a tool useful to analyse risk management attitudes in Northern Italy was conceived and applied in a sample of NHs.

Methods

The tool, developed in collaboration with the health insurance company SHAM Italia, is composed of 124 items (with a dichotomous answer -YES/NO) on topics related to various Risk Management practices. This tool was submitted in a face-to-face interview to several Directors (Health Directors or Nursing Coordinators) of NHs in the Piedmont Region. A list of randomly-chosen NHs was contacted: 4 of them were selected for the pilot study and compiled the questionnaire. Answers were gathered and analyzed through Microsoft Excel.

Results

Only the 25% of NHs has a Risk Management plan with objectives and indicators of effectiveness and uses Risk Analysis instruments for a pre- and post-” risk detection. Only one has employees working mainly on Risk Management alone. The 75% of the reported events were “Adverse Events”, and all the NHs (100%) have a protocol for a patient voluntary departure or for fall prevention or for bedsores prevention; while 50% have a protocol for prevention of aggressions towards operators or for patients' suicide prevention.

Conclusions

This work provides a starting point to face new challenges that are looming on the European Health-care Systems: the care for the elderlies needs to be perfected to reduce inefficiencies, cut useless costs and improve safety of patients in the NHs setting.

Key messages

Despite safety of older patients in nursing homes is not only important but mandatory in Italy, risk management tools for this setting are lacking in literature. A new tool applied in Italian nursing homes showed that risk management needs to be implemented in practice and these results can be extended to European context.

Electrosynthesized poly(pyrrole)/poly(2-naphthol) bilayer membrane as an effective anti-interference layer for simultaneous determination of acethylcholine and choline by a dual electrode amperometric biosensor

Several neural diseases appear related to the neurotransmitter acethylcholine (ACh) and its metabolite choline (Ch) brain levels so that their simultaneous determination is essential. A cross-talk and interference free dual electrode amperometric biosensor for the simultaneous determination of both analytes has been developed. Acetylcholinesterase (AChE) and choline oxidase (ChO) were immobilized by glutaraldehyde co-crosslinking with bovine serum albumin. A very efficient rejection of electroactive interferents has been achieved by a novel electrosynthesized polymeric bilayer membrane composed by overoxidised poly(pyrrole) and poly(2-naphthol) films. Sensitivities towards several electroactive interferents ranged from ca. 0.04% (e.g. ascorbate) to ca. 0.3% (e.g. dopamine) of those relevant to ACh and Ch (11 and 15 microA/microM, respectively). Detection limits (at S/N=3) in flow injection analysis were ca. 100 nM for both ACh and Ch at the ChO-AChE electrode and ca. 40 nM for Ch at the ChO sensor. Biosensor performances appear more than adequate for brain tissue homogenates and cerebrospinal fluids analysis where average levels in the low micromolar range are typically found.

A disposable amperometric biosensor for rapid screening of anticholinesterase activity in soil extracts

A disposable amperometric biosensor for the determination of anticholinesterase activity in soil extracts is described. The sensitive membrane was obtained by co-crosslinking acetylcholinesterase and choline oxidase with bovine serum albumin using glutaraldehyde. The anticholinesterase activity of the soil extract was measured using chronoamperometry at 650 mV vs. Ag/AgCl to monitor the biocatalytically produced H2O2 before and after the inhibition step. An inhibition percentage of 38 +/- 4% was recorded for soil extracts spiked with 10 ppb of ethyl parathion. The device has the potential to be used as a gross sensor for the assessment of anticholinesterase activity in soil extracts.

An acetylcholinesterase/choline oxidase-based amperometric biosensors as a liquid chromatography detector for acetylcholine and choline determination in brain tissue homogenates

A liquid chromatography (LC) detector based on a fast response and sensitive bienzyme amperometric biosensor for acetylcholine (ACh) and choline (Ch) is described. The detector fabrication consisted of glutaraldehyde co-crosslinking of acetylcholinesterase and choline oxidase with bovine serum albumin on the Pt working electrode of a conventional thin-layer electrochemical flow cell. The influence of some experimental parameters (e.g., enzyme loading, thickness of the bienzyme layer, flow rate) on the detector characteristics has been studied in order to optimize the analyte response while minimizing band-broadening and distortion. A mobile phase consisting of a phosphate buffer (I, 0.1 M; pH, 6.5) containing 5 mM sodium hexane sulfonate and 10 mM tetramethylammonium phosphate was found to give very satisfactory resolution and peak shape in ion-pair, reversed-phase LC. Linear responses were observed over at least four decades and absolute detection limits (at a signal-to-noise ratio of 3) were 12 and 27 fmol injected for Ch and ACh, respectively. After one month of intensive use in the LC system, the detector retained about 70% of its initial sensitivity. The potential of the described approach is demonstrated by the simultaneous determination of Ch and ACh in rat brain tissue homogenates.

Electrosynthesized non-conducting polymers as permselective membranes in amperometric enzyme electrodes: a glucose biosensor based on a co-crosslinked glucose oxidase/overoxidized polypyrrole bilayer

A glucose amperometric biosensor based on glucose oxidase immobilized on an overoxidized polypyrrole (PPyox) platinum modified electrode, by glutaraldehyde co-crosslinking with bovine serum albumine, is described. The advantages of covalent immobilization techniques (e.g. high loading and long-term stability of the enzyme) are coupled with the excellent interferent rejection of electrosynthesized non-conducting polymers. The sensor showed an apparent Michaelis-Menten constant of 16 +/- 0.8 mM, a maximum current density of 490 microA/cm2 and a shelf lifetime of at least 3 months. Ascorbate, urate, cysteine and acetaminophen at their maximum physiological concentrations produced a glucose bias in the low micromolar range. Flow-injection response was linear up to 20 mM glucose with typical sensitivity of 84.0 +/- 1.5 nA/mM. The sensor was tested for glucose determination of untreated serum samples from both normal and diabetic subjects; results of amperometric assay compared well with those obtained by a standard enzymatic-colorimetric method.

[Quantitative assessment of pulmonary emphysema with computerized tomography. Comparison of the visual score and high resolution computerized tomography, expiratory density mask with spiral computerized tomography and respiratory function tests]

CT is the most accurate method to detect pulmonary emphysema in vivo. We compared prospectively two different methods for emphysema quantitation in 5 normal volunteers and 20 consecutive patients with chronic obstructive pulmonary disease (COPD). All subjects were submitted to function tests and HRCT; three scans were acquired at preselected levels during inspiration. The type and extent of pulmonary emphysema were defined, using the time-honored visual score system, by two independent observers under blind conditions. Disagreements were subsequently settled by consent. All subjects were also examined with expiratory spiral CT, using a density mask program, at two different cut-off levels (-850, -900 HU). Visual score and expiratory spiral density mask values (-850 HU) were significantly correlated (r = 0.86), but the visual extent of emphysema was always higher than shown by expiratory spiral CT. The emphysema extent assessed with both CT methods correlated with the function result of expiratory airflow obstruction and gas diffusion impairment (visual score versus forced expiratory volume in one second: r = -0.81, versus single breath carbon monoxide diffusion: r = -0.78. Spiral expiratory density mask -850 HU versus forced expiratory volume in one second: r = -0.85, versus single breath carbon monoxide diffusion: r = -0.77). When -900 HU was used as the cut-off value for the expiratory density mask, the correlation with single breath carbon monoxide diffusion worsened (r = -0.56). Visual score and expiratory density mask -850 HU gave similar results and permitted COPD patients to be clearly distinguished from normal controls (p < 0.01). Residual lung volume, measured with expiratory spiral CT correlated significantly with residual volume measured with the helium dilution technique (r = 0.66), but CT values were always higher than function results. We believe the true residual volume should lie somewhere in between the CT value and the function results with the helium dilution technique and conclude that the extent of pulmonary emphysema can be confidently assessed with CT methods. Finally, the simple visual score may be as reliable as such highly sophisticated new methods as the spiral expiratory density mask. Expiratory studies offer new insights into different normal and abnormal features of COPD and respiratory impairment.

Role of palmitic acid on the isolation and properties of halorhodopsin

Purified halorhodopsin was isolated from Halobacterium halobium as previously described (Duschl, A. et al. (1988) J. Biol. Chem. 263, 17016-17022). Two purple bands were eluted from phenyl-Sepharose column, indicating the presence of differently retained halorhodopsin forms; the absorption spectra of the two halorhodopsin bands in the dark were not different. By gas chromatography/mass spectrometry we could identify palmitate (which is only a minor lipid component of archaeal cells) among lipids associated with purple fractions. Typically the palmitate content of the first eluted band was higher than that of the second, indicating a correlation between the palmitate content and the retention time; from one to two fatty acid molecules per halorhodopsin molecule were present depending on the fraction analysed. Very little or no palmitate was released from denatured halorhodopsin. By adding palmitate to buffers used in the phenyl-Sepharose chromatography, only one sharp purple band was collected, corresponding to the less retained halorhodopsin fraction. Pentadecanoic fatty acid could also affect the halorhodopsin chromatography. Chromatography of halorhodopsin in the presence of beta-mercaptoethanol showed only one band, corresponding to the more retrained halorhodopsin form. The two halorhodopsin fractions had different photoreactivity; the less retained halorhodopsin fraction (at higher palmitate content) showed an higher rate of decay of the absorbance at 570 nm upon illumination. By following the decay of the absorbance at 570 nm upon addition of alkali in the dark, we found that the two halorhodopsin fractions had different pKa values of deprotonation.

An on-line semi-automated solid-phase extraction procedure for high-performance liquid chromatographic determination of lonidamine in serum

A semi-automated solid-phase extraction procedure on-line with gradient elution reversed-phase chromatography permits the determination of lonidamine and its metabolite in human serum. The average recovery from serum at the 2.5 micrograms ml-1 level was (92.8 +/- 3.4)%. The limit of quantitation for a 100 microliter sample size was 50 ng ml-1. The within-day (n = 5) and between-day (n = 5) relative standard deviations for lonidamine determination in serum samples spiked at the 2.5 micrograms ml-1 level were 2.7% and 4.5%, respectively.

Effect of antidenaturant drugs on lysozyme deposit formation on soft contact lenses by liquid chromatography--electrochemical detection

The effect of some antidenaturant drugs on the formation of lysozyme deposits on soft contact lenses was investigated by in vitro experiments. Results were obtained which encourage the use of this strategy to reduce lens spoilage. At the same time emphasis is given to the possibility that some functionalities (i.e. lysine groups) present in drug molecules could promote protein adsorption. In order to evaluate at a quantitative level the effectiveness of the drugs used to minimize the formation of deposits on soft contact lenses, a selective method for the determination of adsorbed lysozyme was developed. It is based on the hydrolysis of the 'lens/adsorbed lysozyme' system, followed by high performance liquid chromatography coupled to electrochemical detection of the released tryptophan residues. The lysozyme calibration curve was linear up to 5 mg ml-1 and the detection limit was 5 ng injected.

Solid-phase extraction of fluoropyrimidine derivatives on a copper-modified strong cation exchanger: determination of doxifluridine, 5-fluorouracil and its main metabolites in serum by high-performance liquid chromatography with ultraviolet detection

A copper-modified strong cation exchange stationary phase was used for the solid phase extraction of the antineoplastic drug doxifluridine (5'-deoxy-5-fluorouridine) and some of its main metabolites from human serum. Sorption of fluoropyrimidine derivatives due to complex formation with copper(II) was maximal at pH values around neutrality. Analytes were eluted by ligand exchange with ammonia. The average recoveries ranged from 70% to 108%. Reversed-phase chromatography with ultraviolet detection was used for the separation and quantitation of the analytes. The overall procedure has been applied to serum samples from patients receiving doxifluridine chemotherapy, and a pharmacokinetic profile has been derived.

[The pediatrician and anorexia nervosa. Biological aspects]

Describing a case of anorexia nervosa the Authors review the clinical manifestations and organic alterations of this disease. The Authors point out the signs and symptoms which will usually suggest a diagnosis of anorexia nervosa. The course of the disease is monitored by the metabolic and hormonal analyses and the accompanying psychological features are underlined. The Authors present their therapeutic approach and emphasize the role of psychiatric treatment.

Simultaneous determination of pseudouridine and creatinine in untreated urine by ion-pair liquid chromatography with diode-array ultraviolet detection

A simple procedure for the simultaneous determination of pseudouridine and creatinine in urine using ion-pair high-performance liquid chromatography with ultraviolet detection is described. It consists of simply diluting the filtered urine with mobile phase (1:20) followed by direct chromatographic injection. A single analysis takes only 10 min. This method has been applied to the analysis of urine samples from normal donors and patients with different types of cancer. The mean values, means, of the peak-area ratio of pseudouridine to creatinine were 61.79.10(-3) and 81.92.10(-3) for male and female normal donors, respectively. Out of twenty-five urine samples of patients with cancer examined, nineteen (all the forteen males included) had values higher than means + 2 sigma.

Determination of methotrexate in untreated body fluids by micellar liquid chromatography

A fast and sensitive method for determination of the antineoplastic drug methotrexate in untreated serum and urine is described. Reversed-phase liquid chromatography with sodium dodecyl sulfate (SDS) micellar mobile phase has been used with direct sample injection. Changes in mobile phase variables such as SDS concentration and/or pH profoundly affected drug retention. Recovery was quantitative and the detection limit (90 nM for a 20 microL sample size) was below the range normally monitored. Multichannel UV detection provided strong evidence regarding peak purity and peak identity.

Altered properties of platelet membrane in childhood obesity

Using 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5,hexatriene (TMA-DPH) as fluorescent probe, we have studied platelet membrane fluidity and thrombin induced exocytosis in ten obese children and fifteen controls. Our results indicate a decrease of membrane fluidity, as shown by an increase of fluorescence anisotropy, in platelets from obese patients in comparison with the controls. Associated with the changes in membrane fluidity, platelets of obese subjects showed a decreased sensitivity to thrombin stimulation.

Plasma zinc levels in children with chronic diarrhoea

We measured the plasma zinc concentration in a group of children with chronic diarrhoea. Fifteen patients with untreated coeliac disease had a mean plasma zinc level significantly lower than that of healthy children (69 micrograms/dl vs 96 micrograms/dl). In patients with chronic post-enteritic diarrhoea (n = 70) the mean plasma zinc level was in the normal range (100 micrograms/dl). The latter result suggests that our country a secondary zinc deficiency is not a feature of chronic post-enteritic diarrhoea.

Macroamylasaemia and selective IgA deficiency

Macroamylasaemia and selective IgA deficiency were diagnosed in a 2 year old child who presented with persistent hyperamylasaemia. Macroamylasaemia is an isolated biochemical abnormality caused by aggregation of serum amylase activity with immunoglobulins. Early recognition of macroamylasaemia is important to avoid diagnosing pancreatic disease.

[Zinc and chronic enteropathies]

In recent years the nutritional importance of zinc has been well established; its deficiency and its symptoms have also been recognized in humans. Furthermore, Acrodermatitis Enteropathica has been isolated, a rare but severe disease, of which skin lesions, chronic diarrhoea and recurring infections are the main symptoms. The disease is related to the malfunctioning of intestinal absorption of zinc and can be treated by administering pharmacological doses of zinc orally. Good dietary sources of zinc are meat, fish and, to a less extent, human milk. The amount of zinc absorbed in the small intestine is influenced by other nutrients: some compounds inhibit this process (dietary fiber, phytate) while others (picolinic acid, citric acid), referred to as Zn-binding ligands (ZnBL) facilitate it. Citric acid is thought to be the ligand which accounts for the high level of bioavailability of zinc in human milk. zinc absorption occurs throughout the small intestine, not only in the prossimal tract (duodenum and jejunum) but also in the distal tract (ileum). Diarrhoea is one of the clinical manifestations of zinc deficiency, thus many illnesses distinguished by chronic diarrhoea entail a bad absorption of zinc. In fact, in some cases of chronic enteropathies in infants, like coeliac disease and seldom cystic fibrosis, a deficiency of zinc has been isolated. Some of the symptoms of Crohn's disease, like retarded growth and hypogonadism, have been related to hypozinchemia which is present in this illness. Finally, it is possible that some of the dietary treatments frequently used for persistent post-enteritis diarrhoea (i.e. cow's milk exclusion, abuse and misuse of dietary fiber like carrot and carub powder, use of soy formula) can constitute a scarce supply of zinc and therefore could promote the persistency of diarrhoea itself.