Structural Evolution of GaOx-Shell and Intermetallic Phases in Ga-Pt Supported Catalytically Active Liquid Metal Solutions

We present a comprehensive scale-bridging characterization approach for supported catalytically active liquid metal solutions (SCALMS) which combines lab-based X-ray microscopy, nano X-ray computed tomography (nano-CT), and correlative analytical transmission electron microscopy. SCALMS catalysts consist of low-melting alloy particles and have demonstrated high catalytic activity, selectivity, and long-term stability in propane dehydrogenation (PDH). We established an identical-location nano-CT workflow which allows us to reveal site-specific changes of Ga-Pt SCALMS before and after PDH. These observations are complemented by analytical transmission electron microscopy investigations providing information on the structure, chemical composition, and phase distribution of individual SCALMS particles. Key findings of this combined microscopic approach include (i) structural evolution of the SCALMS particles' GaOx shell, (ii) Pt segregation toward the oxide shell leading to the formation of Ga-Pt intermetallic phases, and (iii) cracking of the oxide shell accompanied by the release of liquid Ga-Pt toward the porous support.

Fast Gas-Adsorption Kinetics in Supraparticle-Based MOF Packings with Hierarchical Porosity

Metal-organic frameworks (MOFs) are microporous adsorbents for high-throughput gas separation. Such materials exhibit distinct adsorption characteristics owing to the flexibility of the crystal framework in a nanoparticle, which can be different from its bulk crystal. However, for practical applications, such particles need to be compacted into macroscopic pellets, creating mass-transport limitations. In this work, this problem is addressed by forming materials with structural hierarchy, using a supraparticle-based approach. Spherical supraparticles composed of nanosized MOF particles are fabricated by emulsion templating and they are used as the structural component forming a macroscopic material. Zeolitic imidazolate framework-8 (ZIF-8) particles are used as a model system and the gas-adsorption kinetics of the hierarchical material are compared with conventional pellets without structural hierarchy. It is demonstrated that a pellet packed with supraparticles exhibits a 30 times faster adsorption rate compared to an unstructured ZIF-8 powder pellet. These results underline the importance of controlling structural hierarchy to maximize the performance of existing materials. In the hierarchical MOFs, large macropores between the supraparticles, smaller macropores between individual ZIF-8 primary particles, and micropores inherent to the ZIF-8 framework collude to combine large surface area, defined adsorption sites, and efficient mass transport to enhance performance.

Controlled Self-Assembly of Gold Nanotetrahedra into Quasicrystals and Complex Periodic Supracrystals

The self-assembly of shape-anisotropic nanocrystals into large-scale structures is a versatile and scalable approach to creating multifunctional materials. The tetrahedral geometry is ubiquitous in natural and manmade materials, yet regular tetrahedra present a formidable challenge in understanding their self-assembly behavior as they do not tile space. Here, we report diverse supracrystals from gold nanotetrahedra including the quasicrystal (QC) and the dimer packing predicted more than a decade ago and hitherto unknown phases. We solve the complex three-dimensional (3D) structure of the QC by a combination of electron microscopy, tomography, and synchrotron X-ray scattering. Nanotetrahedron vertex sharpness, surface ligands, and assembly conditions work in concert to regulate supracrystal structure. We also discover that the surface curvature of supracrystals can induce structural changes of the QC tiling and eventually, for small supracrystals with high curvature, stabilize a hexagonal approximant. Our findings bridge the gap between computational design and experimental realization of soft matter assemblies and demonstrate the importance of accurate control over nanocrystal attributes and the assembly conditions to realize increasingly complex nanopolyhedron supracrystals.

From Meso to Macro: Controlling Hierarchical Porosity in Supraparticle Powders

A drying droplet containing colloidal particles can consolidate into a spherical assembly called a supraparticle. Such supraparticles are inherently porous due to the spaces between the constituent primary particles. Here, the emergent, hierarchical porosity in spray-dried supraparticles is tailored via three distinct strategies acting at different length scales. First, mesopores (<10 nm) are introduced via the primary particles. Second, the interstitial pores are tuned from the meso- (35 nm) to the macro scale (250 nm) by controlling the primary particle size. Third, defined macropores (>100 nm) are introduced via templating polymer particles, which can be selectively removed by calcination. Combining all three strategies creates hierarchical supraparticles with fully tailored pore size distributions. Moreover, another level of the hierarchy is added by fabricating supra-supraparticles, using the supraparticles themselves as building blocks, which provide additional pores with micrometer dimensions. The interconnectivity of the pore networks within all supraparticle types is investigated via detailed textural and tomographic analysis. This work provides a versatile toolbox for designing porous materials with precisely tunable, hierarchical porosity from the meso- (3 nm) to the macroscale (≈10 µm) that can be utilized for applications in catalysis, chromatography, or adsorption.

Dietary exposure to four sizes of spherical polystyrene, polylactide and silica nanoparticles does not affect mortality, behaviour, feeding and energy assimilation of Gammarus roeseli

The abundance and persistence of plastic nanoparticles in aquatic habitats are considered a threat to marine and freshwater biota. However, the risk assessment of plastic particles is complicated due to various factors that need to be considered, including composition, size and environmental abundance. This study investigated the behavioural response of a key river species, Gammarus roeseli, to dietary exposure of plain biodegradable and non-biodegradable plastic as well as to natural small micro- and nanoparticles. Mortality, feeding, swimming velocity and energy assimilation endpoints were examined by considering four particles sizes ranging from 30 to 1000 nm in two concentrations. Contrary to our expectations, neither decreasing size nor increasing abundance of each tested particle impacted any of the examined endpoints. Likewise, dietary exposition with biodegradable plain polylactide did not induce other or stronger effects than non-biodegradable plain polystyrene or natural silica micro- and nanoparticles, as all three particle types did not lead to adverse effects on G. roeseli. These findings also suggest that the functional role of Gammarus roeseli as a shredder is not impaired due to particle occurrence within the exposure range of this study.

Non-canonical Shedding of TNFα by SPPL2a Is Determined by the Conformational Flexibility of Its Transmembrane Helix

Ectodomain (EC) shedding defines the proteolytic removal of a membrane protein EC and acts as an important molecular switch in signaling and other cellular processes. Using tumor necrosis factor (TNF)α as a model substrate, we identify a non-canonical shedding activity of SPPL2a, an intramembrane cleaving aspartyl protease of the GxGD type. Proline insertions in the TNFα transmembrane (TM) helix strongly increased SPPL2a non-canonical shedding, while leucine mutations decreased this cleavage. Using biophysical and structural analysis, as well as molecular dynamic simulations, we identified a flexible region in the center of the TNFα wildtype TM domain, which plays an important role in the processing of TNFα by SPPL2a. This study combines molecular biology, biochemistry, and biophysics to provide insights into the dynamic architecture of a substrate's TM helix and its impact on non-canonical shedding. Thus, these data will provide the basis to identify further physiological substrates of non-canonical shedding in the future.

Apparent penetration depth in attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy of Allium cepa L. epidermis and cuticle

Over the past decades, ATR-FTIR has emerged as promising tool for the identification of plants at the genus and (sub-) species level through surface measurements of intact leaves. Theoretical considerations regarding the penetration depth of the evanescent wave into the sample and the thickness of plant leaf cuticles suggest that the structure and composition of the cuticle represent universal taxonomic markers. However, experimental evidence for this hypothesis is scarce. In the current contribution, we present results of a series of simple experiments on epidermal monolayers derived from the bulbs of Allium cepa L. (Amaryllidaceae) as a model system to study the effect of an IR active probe located beyond the theoretical penetration depth of the evanescent wave. We found that this probe had a significant influence on the ATR-FTIR spectra for up to 4 epidermal layers stacked on top of each other corresponding to a total thickness of around 60 μm, exceeding the theoretical penetration depth of the evanescent wave by a factor of around 20. Altogether, our data indicate a major discrepancy between theory and practice in ATR-FTIR spectroscopy in general and provide strong evidence that in general plant leaf spectra cannot be fully explained by the structure and composition of the cuticle alone.

Modulating Hinge Flexibility in the APP Transmembrane Domain Alters γ-Secretase Cleavage

Intramembrane cleavage of the β-amyloid precursor protein C99 substrate by γ-secretase is implicated in Alzheimer's disease pathogenesis. Biophysical data have suggested that the N-terminal part of the C99 transmembrane domain (TMD) is separated from the C-terminal cleavage domain by a di-glycine hinge. Because the flexibility of this hinge might be critical for γ-secretase cleavage, we mutated one of the glycine residues, G38, to a helix-stabilizing leucine and to a helix-distorting proline. Both mutants impaired γ-secretase cleavage and also altered its cleavage specificity. Circular dichroism, NMR, and backbone amide hydrogen/deuterium exchange measurements as well as molecular dynamics simulations showed that the mutations distinctly altered the intrinsic structural and dynamical properties of the substrate TMD. Although helix destabilization and/or unfolding was not observed at the initial ε-cleavage sites of C99, subtle changes in hinge flexibility were identified that substantially affected helix bending and twisting motions in the entire TMD. These resulted in altered orientation of the distal cleavage domain relative to the N-terminal TMD part. Our data suggest that both enhancing and reducing local helix flexibility of the di-glycine hinge may decrease the occurrence of enzyme-substrate complex conformations required for normal catalysis and that hinge mobility can thus be conducive for productive substrate-enzyme interactions.

Increased H-Bond Stability Relates to Altered ε-Cleavage Efficiency and Aβ Levels in the I45T Familial Alzheimer's Disease Mutant of APP

Cleavage of the amyloid precursor protein's (APP) transmembrane domain (TMD) by γ-secretase is a crucial step in the aetiology of Alzheimer's Disease (AD). Mutations in the APP TMD alter cleavage and lead to familial forms of AD (FAD). The majority of FAD mutations shift the preference of initial cleavage from ε49 to ε48, thus raising the AD-related Aβ42/Aβ40 ratio. The I45T mutation is among the few FAD mutations that do not alter ε-site preference, while it dramatically reduces the efficiency of ε-cleavage. Here, we investigate the impact of the I45T mutation on the backbone dynamics of the substrate TMD. Amide exchange experiments and molecular dynamics simulations in solvent and a lipid bilayer reveal an increased stability of amide hydrogen bonds at the ζ- and γ-cleavage sites. Stiffening of the H-bond network is caused by an additional H-bond between the T45 side chain and the TMD backbone, which alters dynamics within the cleavage domain. In particular, the increased H-bond stability inhibits an upward movement of the ε-sites in the I45T mutant. Thus, an altered presentation of ε-sites to the active site of γ-secretase as a consequence of restricted local flexibility provides a rationale for reduced ε-cleavage efficiency of the I45T mutant.

Dissecting conformational changes in APP's transmembrane domain linked to ε-efficiency in familial Alzheimer's disease

The mechanism by which familial Alzheimer's disease (FAD) mutations within the transmembrane domain (TMD) of the Amyloid Precursor Protein (APP) affect ε-endoproteolysis is only poorly understood. Thereby, mutations in the cleavage domain reduce ε-efficiency of γ-secretase cleavage and some even shift entry into production lines. Since cleavage occurs within the TMD, a relationship between processing and TMD structure and dynamics seems obvious. Using molecular dynamic simulations, we dissect the dynamic features of wild-type and seven FAD-mutants into local and global components. Mutations consistently enhance hydrogen-bond fluctuations upstream of the ε-cleavage sites but maintain strong helicity there. Dynamic perturbation-response scanning reveals that FAD-mutants target backbone motions utilized in the bound state. Those motions, obscured by large-scale motions in the pre-bound state, provide (i) a dynamic mechanism underlying the proposed coupling between binding and ε-cleavage, (ii) key sites consistent with experimentally determined docking sites, and (iii) the distinction between mutants and wild-type.

Influence of denaturation and aggregation of β-lactoglobulin on its tryptic hydrolysis and the release of functional peptides

Whereas previous studies showed that thermal pre-treatment of whey proteins promote their enzymatic hydrolysis, to date no correlation between the conformation of denatured protein and the release of individual peptides has been considered. Hence, in this study total denaturation of β-lactoglobulin was performed at defined pH-values to enable the generation of different denatured particles. The denatured proteins were used as substrate for tryptic hydrolysis and the hydrolysis progress was characterised by the degree of hydrolysis (DH) and the release of functional peptides, detected using LC-ESI-TOF/MS. Denaturation and subsequent aggregation of β-lactoglobulin, induced by thermal treatment at pH 5.1, altered the DH slightly, whereas the release of investigated peptides was significantly decreased. Contrary, denaturation at pH 6.8 and 8.0 led to formation of non-native monomers and reduced the DH to 75%, but showed promoting as well as reducing effects on the release of peptides, depending on their location within the protein.

Tyrphostin AG126 exerts neuroprotection in CNS inflammation by a dual mechanism

The putative protein tyrosine kinase (PTK) inhibitor tyrphostin AG126 has proven beneficial in various models of inflammatory disease. Yet molecular targets and cellular mechanisms remained enigmatic. We demonstrate here that AG126 treatment has beneficial effects in experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. AG126 alleviates the clinical symptoms, diminishes encephalitogenic Th17 differentiation, reduces inflammatory CNS infiltration as well as microglia activation and attenuates myelin damage. We show that AG126 directly inhibits Bruton's tyrosine kinase (BTK), a PTK associated with B cell receptor and Toll-like receptor (TLR) signaling. However, BTK inhibition cannot account for the entire activity spectrum. Effects on TLR-induced proinflammatory cytokine expression in microglia involve AG126 hydrolysis and conversion of its dinitrile side chain to malononitrile (MN). Notably, while liberated MN can subsequently mediate critical AG126 features, full protection in EAE still requires delivery of intact AG126. Its anti-inflammatory potential and especially interference with TLR signaling thus rely on a dual mechanism encompassing BTK and a novel MN-sensitive target. Both principles bear great potential for the therapeutic management of disturbed innate and adaptive immune functions.

Side-chain to main-chain hydrogen bonding controls the intrinsic backbone dynamics of the amyloid precursor protein transmembrane helix

Many transmembrane helices contain serine and/or threonine residues whose side chains form intrahelical H-bonds with upstream carbonyl oxygens. Here, we investigated the impact of threonine side-chain/main-chain backbonding on the backbone dynamics of the amyloid precursor protein transmembrane helix. This helix consists of a N-terminal dimerization region and a C-terminal cleavage region, which is processed by γ-secretase to a series of products. Threonine mutations within this transmembrane helix are known to alter the cleavage pattern, which can lead to early-onset Alzheimer's disease. Circular dichroism spectroscopy and amide exchange experiments of synthetic transmembrane domain peptides reveal that mutating threonine enhances the flexibility of this helix. Molecular dynamics simulations show that the mutations reduce intrahelical amide H-bonding and H-bond lifetimes. In addition, the removal of side-chain/main-chain backbonding distorts the helix, which alters bending and rotation at a diglycine hinge connecting the dimerization and cleavage regions. We propose that the backbone dynamics of the substrate profoundly affects the way by which the substrate is presented to the catalytic site within the enzyme. Changing this conformational flexibility may thus change the pattern of proteolytic processing.

Innovations in phenotyping of mouse models in the German Mouse Clinic

Under the label of the German Mouse Clinic (GMC), a concept has been developed and implemented that allows the better understanding of human diseases on the pathophysiological and molecular level. This includes better understanding of the crosstalk between different organs, pleiotropy of genes, and the systemic impact of envirotypes and drugs. In the GMC, experts from various fields of mouse genetics and physiology, in close collaboration with clinicians, work side by side under one roof. The GMC is an open-access platform for the scientific community by providing phenotypic analysis in bilateral collaborations ("bottom-up projects") and as a partner and driver in international large-scale biology projects ("top-down projects"). Furthermore, technology development is a major topic in the GMC. Innovative techniques for primary and secondary screens are developed and implemented into the phenotyping pipelines (e.g., detection of volatile organic compounds, VOCs).

[Plain abdominal radiograph - is there any additional clinical value based on the supine projection?]

BACKGROUND

To assess the diagnostic value of an additionally acquired plain abdominal radiograph in supine position.

MATERIALS AND METHODS

Two experienced radiologists evaluated retrospectively 2148 consecutive patients having plain abdominal radiographs acquired in a tertiary care center. There were 1385 patients having an erect view and 763 patients with a left lateral decubitus view. All patients had a second examination in supine position. First the radiographs in erect or decubitus view were evaluated regarding the presence and details of pathological changes. After 4 weeks all radiographs including the supine view were evaluated again. Next to pathological changes the additional value of the supine projection was assessed. The results were compared and the additional diagnostic value using the supine view was noted.

RESULTS

We evaluated 2148 patients having a plain abdominal radiograph (1325 men, 823 women, mean 58.9 years, range 15-96 years). The average age within the group acquired with left decubitus view was 61.1 years, while patients having an erect view had a mean age of 57.0 years. For the first evaluation we found pathological changes in 10.5% (decubitus view: 13.1%, erect view 9.5%; p = 0.01). The most frequent diagnosis was ileus (7.7%) followed by abdominal free air (2.4%). The results were confirmed during the second reading in 99.2%. In 3.5% (decubitus view 5.8%, erect view 2.2%) more anatomical structures were depicted considering the supine projection and the decubitus/erect projections. The anatomical information was in no case relevant for the diagnosis.

CONCLUSION

Having the information of an supine view additionally to an decubitus/erect view increases the depiction of anatomical structures up to 5.8%. Nevertheless there was no additional diagnostic relevant information based on the supine view.

Requirement of the RNA-editing enzyme ADAR2 for normal physiology in mice

ADAR2, an RNA editing enzyme that converts specific adenosines to inosines in certain pre-mRNAs, often leading to amino acid substitutions in the encoded proteins, is mainly expressed in brain. Of all ADAR2-mediated edits, a single one in the pre-mRNA of the AMPA receptor subunit GluA2 is essential for survival. Hence, early postnatal death of mice lacking ADAR2 is averted when the critical edit is engineered into both GluA2 encoding Gria2 alleles. Adar2(-/-)/Gria2(R/R) mice display normal appearance and life span, but the general phenotypic effects of global lack of ADAR2 have remained unexplored. Here we have employed the Adar2(-/-)/Gria2(R/R) mouse line, and Gria2(R/R) mice as controls, to study the phenotypic consequences of loss of all ADAR2-mediated edits except the critical one in GluA2. Our extended phenotypic analysis covering ∼320 parameters identified significant changes related to absence of ADAR2 in behavior, hearing ability, allergy parameters and transcript profiles of brain.

Mouse phenotyping

Model organisms like the mouse are important tools to learn more about gene function in man. Within the last 20 years many mutant mouse lines have been generated by different methods such as ENU mutagenesis, constitutive and conditional knock-out approaches, knock-down, introduction of human genes, and knock-in techniques, thus creating models which mimic human conditions. Due to pleiotropic effects, one gene may have different functions in different organ systems or time points during development. Therefore mutant mouse lines have to be phenotyped comprehensively in a highly standardized manner to enable the detection of phenotypes which might otherwise remain hidden. The German Mouse Clinic (GMC) has been established at the Helmholtz Zentrum München as a phenotyping platform with open access to the scientific community (www.mousclinic.de; [1]). The GMC is a member of the EUMODIC consortium which created the European standard workflow EMPReSSslim for the systemic phenotyping of mouse models (http://www.eumodic.org/[2]).

Stigmatization experience, coping and sense of coherence in vitiligo patients

OBJECTIVE

This study examines the extent of stigmatization experienced by vitiligo patients considering the visibility of the lesions.

METHODS

363 vitiligo patients were assessed using the Experience with Skin Complaints (QES), Adjustment to Chronic Skin Disorders (ASC), and Sense of Coherence (SOC) questionnaires. Out of the total patients group two representative samples with 52 patients each were identified comparable for age, gender, and the duration of the skin disease, the first with visible and the second with invisible lesions.

RESULTS

Data indicate a significant negative correlation between the QES dimensions, except for 'Composure', and between coping scales with sense of coherence withstanding. The 'visible lesions' group scored higher compared to the 'invisible lesions' group on the two QES scales 'Self-Esteem' and 'Refusal', i.e., patients with visible lesions experienced a higher level of stigmatization.

CONCLUSION

This study provides new information which supports the notion that the stigmatization experience of vitiligo patients is psychologically relevant.

A new approach to determining the content and 15N abundance of total dissolved nitrogen in aqueous samples: TOC analyser-QMS coupling

The standard method for determining the 15N abundance of total dissolved nitrogen (TDN) in aqueous samples (e.g., soil leachate, sewage, urine) is currently Kjeldahl digestion followed by steam distillation or diffusion to isolate the ammonium, and then 15N measurement using IRMS. However, this technique is both time-consuming and laborious. One way of overcoming these disadvantages could be to couple a TOC analyser to determine the TDN with a sufficient quadrupole MS to determine the 15N abundance. The high TOC analyser (Elementar Analysensysteme Hanau, Germany), which catalytically oxidises the sample's total nitrogen with a high, constant yield to nitrogen monoxide (NO), appeared particularly suitable. The quadrupole-MS ESD 100 (InProcess Instruments Bremen, Germany) proved to be a suitable mass spectrometer for the 15N determination of NO. This combination of instruments was found to provide a workable method in numerous measurements of standard and actual samples. The detection limit concerning the N amount required per analysis is 2 microg, corresponding to an N concentration of 0.7 mg/l in a maximum sample volume of 3ml. Depending on the N concentration, 15N abundances starting from 0.5 at.% can be measured with the required precision of better than 3% (simple standard deviation). For example, measuring the abundance of 0.5 at.% requires about 50 microg N, whereas for 1 at.% or more only about 5 microg N is needed per analysis.

[Only for limited indications. Biventricular pacemaker improves severe heart failure]

In patients with congestive heart disease in whom left ventricular dilatation is associated with severely disordered contraction due to delayed ventricular conduction, a new form of treatment not requiring drugs is currently becoming established--biventricular pacing. Via an implanted electrode, biventricular stimulation accelerates conduction in the left ventricle and resynchronizes its contraction. Patients being considered for such therapy must have stable stage III disease (NYHA classification) under optimal medication, and a left bundle branch block with a QRS of at least 150 ms. Definitive recommendations with regard to indications will be possible only when current randomized mortality studies have been concluded.

[Clinical symptoms, origin, and therapy of the "pusher syndrome"]

Stroke patients may exhibit the peculiar behavior of actively pushing away from the nonhemiparetic side, leading to lateral postural imbalance and a tendency to fall towards the paralyzed side. These patients use the nonparetic extremities to stem actively against attempts of passive correction towards upright orientation. This phenomenon has been called the "pusher syndrome". Recent findings disclose that the deficit leading to contraversive pushing is an altered perception of the body's orientation in relation to gravity. Pusher patients experience their body as upright when they are actually tilted to the nonhemiparetic side. In contrast, processing of visual and vestibular inputs for the determination of visual vertical was undisturbed. The results argue for a separate pathway in humans for sensing gravity apart from that for perception of the visual world. This second graviceptive system decisively contributes to our control of upright body posture. The present article describes this still largely unknown neurological disease. The clinical examination of contraversive pushing, its underlying disturbance, lesion location, and approaches for therapy are considered.

Exogenous isolation of antibiotic resistance plasmids from piggery manure slurries reveals a high prevalence and diversity of IncQ-like plasmids

Antibiotic resistance plasmids were exogenously isolated in biparental matings with piggery manure bacteria as plasmid donors in Escherichia coli CV601 and Pseudomonas putida UWC1 recipients. Surprisingly, IncQ-like plasmids were detected by dot blot hybridization with an IncQ oriV probe in several P. putida UWC1 transconjugants. The capture of IncQ-like plasmids in biparental matings indicates not only their high prevalence in manure slurries but also the presence of efficiently mobilizing plasmids. In order to elucidate unusual hybridization data (weak or no hybridization with IncQ repB or IncQ oriT probes) four IncQ-like plasmids (pIE1107, pIE1115, pIE1120, and pIE1130), each representing a different EcoRV restriction pattern, were selected for a more thorough plasmid characterization after transfer into E. coli K-12 strain DH5alpha by transformation. The characterization of the IncQ-like plasmids revealed an astonishingly high diversity with regard to phenotypic and genotypic properties. Four different multiple antibiotic resistance patterns were found to be conferred by the IncQ-like plasmids. The plasmids could be mobilized by the RP4 derivative pTH10 into Acinetobacter sp., Ralstonia eutropha, Agrobacterium tumefaciens, and P. putida, but they showed diverse patterns of stability under nonselective growth conditions in different host backgrounds. Incompatibility testing and PCR analysis clearly revealed at least two different types of IncQ-like plasmids. PCR amplification of total DNA extracted directly from different manure samples and other environments indicated the prevalence of both types of IncQ plasmids in manure, sewage, and farm soil. These findings suggest that IncQ plasmids play an important role in disseminating antibiotic resistance genes.

Detection of membrane-bound tumor necrosis factor (TNF): an analysis of TNF-specific reagents

Tumor necrosis factor (TNF) exists in two bioactive forms, the membrane integrated form and the proteolytically derived soluble cytokine. Both forms of TNF are involved in a variety of different physiological and pathophysiological situations. Here we analyzed different human and mouse TNF-specific reagents for their ability to determine the expression of membrane-expressed TNF. The data prove some antibodies to be very useful for the analysis of transmembrane TNF expression because these antibodies distinguish between the transmembrane form of TNF and soluble TNF bound to cellular TNF receptors. In addition, we found that recombinant human TNF receptor fusion proteins are advantageous tools to analyze both human and mouse transmembrane TNF expression.

The tyrosine kinase inhibitor CGP 57148 (ST1 571) induces apoptosis in BCR-ABL-positive cells by down-regulating BCL-X

CGP 57148 is a potent inhibitor of the ABL protein tyrosine kinase and a promising new compound for the treatment of a variety of BCR-ABL-positive leukemias. We used this enzyme inhibitor to characterize the biological effects of BCR-ABL in primary cells and two growth factor-dependent BCR-ABL-transfected cell lines. The effect of CGP 57148 on primary cells is dependent on the stage of differentiation. The growth of maturing chronic myeloid leukemia cells is independent of BCR-ABL in the presence of growth factors. However, the proliferation of leukemic immature cobblestone-forming area cells is almost completely blocked after the inhibition of the BCR-ABL kinase. In the BCR-ABL-transfected cell lines, M07/ p210 and Ba/F3/p185, CGP 57148 induces apoptosis by releasing cytochrome c, activating caspase 3, and cleavage of PARP. No alteration of the expression level of the apoptosis regulator BCL-2 was observed. In contrast, BCL-X was down-regulated after exposure to CGP 57148. Inhibitors of signal transduction proteins such as PI-3 kinase, mitogen-activated protein/extracellular signal-regulated kinase kinase, and Janus-activated kinase 2 pathways were not capable of a comparable down-regulation of BCL-X. The Fas/Fas ligand system was not involved either in the induction of apoptosis by CGP 57148. We conclude that the inhibition of the BCR-ABL kinase by CGP 57148 (a) preferentially inhibits the growth of immature leukemic precursor cells, (b) efficiently reverts the antiapoptotic effects of BCR-ABL by down-regulation of BCL-X, and (c) is more effective than the inhibition of the downstream signal transduction pathways of PI-3 kinase, mitogen-activated protein/extracellular signal-regulated kinase kinase, and Janus-activated kinase 2.

Transport of lipids from golgi to plasma membrane is defective in tangier disease patients and Abc1-deficient mice

Mutations in the gene encoding ATP-binding cassette transporter 1 ( ABC1) have been reported in Tangier disease (TD), an autosomal recessive disorder that is characterized by almost complete absence of plasma high-density lipoprotein (HDL), deposition of cholesteryl esters in the reticulo-endothelial system (RES) and aberrant cellular lipid trafficking. We demonstrate here that mice with a targeted inactivation of Abc1 display morphologic abnormalities and perturbations in their lipoprotein metabolism concordant with TD. ABC1 is expressed on the plasma membrane and the Golgi complex, mediates apo-AI associated export of cholesterol and phospholipids from the cell, and is regulated by cholesterol flux. Structural and functional abnormalities in caveolar processing and the trans-Golgi secretory pathway of cells lacking functional ABC1 indicate that lipid export processes involving vesicular budding between the Golgi and the plasma membrane are severely disturbed.

Surgical versus medical care for postoperative cardiac surgical patients at the general ward

OBJECTIVES

To shorten hospital stay after cardiac surgery, several risk factors have been defined to identify patients who can be discharged early. These risk factors are dependant on the patient; no studies exist on the influence of the treating physician himself on postoperative patient stay.

METHODS

In a university affiliated cardiac surgical clinic we investigated patients who were postoperatively treated either on medical wards with no cardiac surgeon's presence or on a cardiac surgical ward; at both types of wards physicians had several years experience with cardiac surgical patients. Taking several risk factors for postoperative morbidity into account, postoperative length of stay and incidence of wound healing complications have been compared.

RESULTS

Within a 3-month period, 84 patients were treated at the cardiac surgical ward, 102 patients at the medical wards. Risk factors for postoperative morbidity were present in 87% of patients, statistically independent of postoperative wards. Although demographic data and median ICU-stay of both patient groups was comparable, the median post-ICU stay was 9 days at the surgical and 13 days at the medical wards (P < 0.0001). Incidence of wound healing complication was higher (19.6%) at the medical wards than at the surgical ward (10.7%), without reaching statistical significance.

CONCLUSION

As patients at the respective wards were statistically not different, the difference in post-ICU stay, infection and costs must depend on the treating physicians. As a consequence, postoperative care for cardiac surgical patients in all cases should include direct cardiac surgical participation.

[Porokeratosis Mibelli gigantea: case report and literature review]

Porokeratos of Mibelli is a rare inherited disorder of epidermal keratinization, whose pathogenesis is not fully understood. The common clinical feature is a erythematous plaque surrounded by a hyperkeratotic border. The histopathologic hallmark is a parakeratotic cornoid lamella. An unusual case of porokeratosis gigantea, a morphological variant of classical porokeratosis of Mibelli, is reported. The pathogenesis, taking in account especially the clonal hypothesis and premalignant nature of porokeratosis, is discussed.

Detection and characterization of broad-host-range plasmids in environmental bacteria by PCR

Primer systems for PCR amplification of different replicon-specific DNA regions were designed on the basis of published sequences for plasmids belonging to the incompatibility (Inc) groups IncP, IncN, IncW, and IncQ. The specificities of these primer systems for the respective Inc groups were tested with a collection of reference plasmids belonging to 21 different Inc groups. Almost all primer systems were found to be highly specific for the reference plasmid for which they were designed. In addition, the primers were tested with plasmids which had previously been grouped by traditional incompatibility testing to the IncN, IncW, IncP, or IncQ group. All IncQ plasmids gave PCR products with the IncQ primer systems tested. However, PCR products were obtained for only some of the IncN, IncP, and IncW group plasmids. Dot blot and Southern blot analyses of the plasmids revealed that PCR-negative plasmids also failed to hybridize with probes derived from the reference plasmids. The results indicated that plasmids assigned to the same Inc group by traditional methods might be partially or completely different from their respective reference plasmids at the DNA level. With a few exceptions, all plasmids related to the reference plasmid at the DNA level also reacted with the primer systems tested. PCR amplification of total DNA extracted directly from different soil and manure slurry samples revealed the prevalence of IncQ- and IncP-specific sequences in several of these samples. In contrast, IncN- and IncW-specific sequences were detected mainly in DNA obtained from manure slurries.

Characteristic but unfamiliar--the cowpox infection, transmitted by a domestic cat

An 11-year-old girl had been suffering from 2 recently developed reddish ulcerated nodules on the right side of her neck and, concomitantly, from a very hard swelling as well as from painless lymphadenopathy. Subsequently, thick black eschars appeared on the surface of the ulcers. Using the negative staining technique, an orthopox virus infection could be identified by electron microscopy. The patient's characteristic history as well as her close contact with a cat frequently hunting nice indicated the diagnosis of a cowpox infection, which was unequivocally confirmed by identification of both the viral culture and specific antibodies in the serum of the patient.

The IRMM--International Measurement Evaluation Program (IMEP). IMEP-3--trace elements in synthetic and natural water

The aim of the IRMM--International Measurement Evaluation Program (IMEP) is to test out a possible realization of international measurement comparability for field laboratories through traceability of their measurements to the SI Unit for amount of substance: the mole. In IMEP-3, 10 different trace elements, B, Ca, Cd, Cu, Fe, K, Li, Pb, Rb, and Zn, were determined in a synthetic and a natural water by participating laboratories using their routine methods and graphically compared (in coded form) to certified values, established by IRMM and NIST using an isotope-specific method (Isotope Dilution Mass Spectrometry, Neutron Activation Analysis). The number of participants was 70; 64 laboratories have reported results. The results show a spread of more than 50% asymmetrically around the certified value. The Youden graphs allow evaluation of the overall performance of the laboratories in the IMEP-3 round.