231 research outputs found
Temporal and spatial trends for trace metals in streams and rivers across Sweden (1996-2009)
No full textLong term data series (1996 through 2009) for trace metals were analyzed from a large number of streams and rivers across Sweden varying in tributary watershed size from 0.05 to 48 193 km(2). The final data set included 139 stream sites with data for arsenic (As), cobalt (Co), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), and vanadium (V). Between 7% and 46% of the sites analyzed showed significant trends according to the seasonal Kendall test. However, in contrast to previous studies and depositional patterns, a substantial portion of the trends were positive, especially for V (100%), As (95%), and Pb (68%). Other metals (Zn and Cr) generally decreased, were mixed (Ni and Zn), or had very few trends (Co) over the study period. Trends by region were also analyzed and some showed significant variation between the north and south of Sweden. Regional trends for both Cu and Pb were positive (60% and 93%, respectively) in the southern region but strongly negative (93% and 75 %, respectively) in the northern region. Kendall's tau coefficients were used to determine dependence between metals and potential in-stream drivers including total organic carbon (TOC), iron (Fe), pH, and sulphate (SO(4)(2-)). TOC and Fe correlated positively and strongly with As, V, Pb, and Co while pH and SO(4)(2) generally correlated weakly, or not at all with the metals studied
Plasmon optics of structured silver films
No full textBouhelier A, Huser T, Tamaru H, et al. Plasmon optics of structured silver films. PHYSICAL REVIEW B. 2001;63(15): 155404.Excitation and propagation of surface plasmons in silver films structured with narrow straight grooves were visualized in unprecedented detail by means of near-field optical techniques. Reflectivity, transmissivity, and scattering loss of the grooves are demonstrated. Their values are determined semiquantitatively. The surface plasmon attenuation are found to be dominated by material and surface/interface imperfections
Instrumental developments and recent experiments in near-field optical microscopy
No full textHeinzelmann H, Lacoste T, Huser T, Güntherodt HJ, Hecht B, Pohl DW. Instrumental developments and recent experiments in near-field optical microscopy. Thin Solid Films. 1996;273(1-2):149-153.Recent advances in the understanding of light propagation in small dimensions as well as in instrumentation make scanning near-field optical microscopy (SNOM) a very promising tool for studying optical phenomena on a nanometer scale. In this talk, we will demonstrate experiments carried out with the recently developed tunneling near-field optical microscope. We found superior image contrast, as compared with images taken with conventional aperture SNOM, along with the high resolution commonly achieved with fiber probes. This work was motivated by the theoretical investigations presented in Dr. Pohl's talk. We will further describe two recently built instruments. The first is a scanning tunneling optical microscope combined with a scanning force microscope. The second instrument is an aperture-type SNOM mounted on the sample stage of a conventional inverted optical microscope. Of particular interest to us is imaging with polarization contrast. One of the goals is to study liquid-crystal films which have been micropatterned with the help of a force microscope tip. These samples are promising as waveguides and potential electro-optical devices. Additionally, they represent very convenient test samples for polarization SNOM
Scanning Near-Field Optical Microscopy in Basel, Ruschlikon, and Zurich
No full textHeinzelmann H, Huser T, Lacoste T, et al. Scanning Near-Field Optical Microscopy in Basel, Ruschlikon, and Zurich. Optical Engineering. 1995;34(8):2441-2454.The concepts of near-field optical microscopy and experimental and theoretical work carried out in Switzerland over the last 10 years are reviewed. After a description of the pioneering experiments of the mid-1980s, we focus on the recent efforts of the three Swiss laboratories currently working in the field in close collaboration. This newly refreshed initiative in near-field optics is supported by the Swiss Priority Program Optique
Isolation and characterisation of a novel extremely thermophilic, anaerobic, chemo-organotrophic eubacterium
No full textA new, extremely thermophilic, anaerobic, chemo-organotrophic bacterium was isolated from intertidal habitats where seepage of geothermally heated water occurs. The antibiotic sensitivity pattern and the presence of muramic acid strongly suggest an eubacterial nature of the novel isolate. Growth was measured between pH 4.8–8.2 (optimal pH 7.0) and at temperatures up to 90°C with a doubling time of 50 min at optimal temperatures of 80–85°C. This is the highest optimal growth temperature for an eubacterium described so far.\ud
\ud
The Gram-negative, non-motile, non-sporulating, short rod to coccal shaped cells were enclosed in a sphere-like cell envelope protruding from either end. A wide range of carbohydrates, including xylose, glucose, fructose, maltose, starch, carboxymethylcellulose, and amylopectin were used in an obligately fermentative metabolism.\ud
\ud
Morphological, physiological and molecular properties (mol% G + C = 46) are distinct from other known extremely thermophilic eubacterial genera
Nondestructive identification of individual leukemia cells by laser trapping Raman spectroscopy
No full textChan JW, Taylor DS, Lane SM, Zwerdling T, Tuscano J, Huser T. Nondestructive identification of individual leukemia cells by laser trapping Raman spectroscopy. Analytical Chemistry. 2008;80(6):2180-2187.Currently, a combination of technologies is typically required to assess the malignancy of cancer cells. These methods often lack the specificity and sensitivity necessary for early, accurate diagnosis. Here we demonstrate using clinical samples the application of laser trapping Raman spectroscopy as a novel approach that provides intrinsic biochemical markers for the noninvasive detection of individual cancer cells. The Raman spectra of live, hematopoietic cells provide reliable molecular fingerprints that reflect their biochemical composition and biology. Populations of normal T and B lymphocytes from four healthy individuals and cells from three leukemia patients were analyzed, and multiple intrinsic Raman markers associated with DNA and protein vibrational modes have been identified that exhibit excellent discriminating power for cancer cell identification. A combination of two multivariate statistical methods, principal component analysis (PCA) and linear discriminant analysis (LDA), was used to confirm the significance of these markers for identifying cancer cells and classifying the data. The results indicate that, on average, 95% of the normal cells and 90% of the patient cells were accurately classified into their respective cell types. We also provide evidence that these markers are unique to cancer cells and not purely a function of differences in their cellular activation
A role for amphiphysin in AP-1/clathrin coat formation
No full textTransport of cargo within the endocytic and secretory pathway is generally mediated by coated vesicles. Clathrin, in combination with different adaptor proteins, is the major coat protein for vesicle formation at the plasma membrane, endosomes, and the trans-Golgi network (TGN). Best characterized is the formation of clathrin coats for endocytosis at the plasma membrane involving the adaptor protein complex AP-2. Clathrin and AP-2 were shown to be at the centre of a complex interactome of proteins accessory to vesicle formation. Considerably less is known about the formation of clathrin coated carriers at the TGN and endosomes, where the adaptor protein complex AP-1 plays a major role.
In vitro studies showed the minimal requirements for association of AP-1 to liposomal membranes to be activated ARF1, phosphoinositides, and either sorting signals or unknown cytosolic factors. We have used a liposome floatation assay to identify cytosolic proteins collaborating with AP-1 at the membrane. Separation of proteins from bovine brain cytosol with several chromatographic methods yielded an active fraction containing amphiphysin 1, amphiphysin 2, and endophilin A1. All three proteins are expressed in brain and known to be involved in AP-2/clathrin coat formation. They consist of an N-terminal N-BAR (Bin, amphiphysin, Rvs) domain for dimerization and membrane binding and a C-terminal SH3 (Src homology 3) domain for interaction with dynamin and synaptojanin. Amphiphysin 1 and 2 in addition contain a middle domain with binding sites for adaptors and clathrin. It was proposed that amphiphysins and endophilin are targeted to membranes with high curvature, such as the neck of a forming vesicle, where they recruit dynamin and synaptojanin in preparation for vesicle fission and uncoating.
In this thesis, I bacterially expressed and purified all three proteins and tested them in the floatation assay for AP-1 membrane binding activity. Only amphiphysin 2 showed activity, both as a homodimer and as a heterodimer with amphiphysin 1. Activity depended on a motif that was shown to bind to AP-1, AP-2, and clathrin in GST pull-down experiments.
Endogenous amphiphysins in primary neurons, as well as transiently expressed in neuronal or fibroblast cell lines, co-localized with AP-1 at the TGN. In addition, when expressed at high levels in neuronal cells, amphiphysins aggregated and interfered dominantly with the TGN localization of AP-1. Both phenomena depended on the presence of the clathrin and adaptor interaction sequence in the amphiphysins. Furthermore, both amphiphysins could be cross-linked to AP-1 in vivo.
Our results indicate that amphiphysin 1 and 2 function not only in clathrin coated vesicle formation for endocytosis at the plasma membrane, but are also part of the machinery forming AP-1/clathrin coats at the TGN and endosomes. This suggests that the machineries for CCV formation with AP-1 and AP-2 at different locations in the cell share more components than previously anticipated
Recommended from our members
Sayh al Uhaymir 094: A new martian meteorite from the Oman desert
No full textSayh al Uhaymir 094 is a 223.3 g, partially crusted, strongly to very strongly shocked melanocratic olivine-porphyric rock of the shergottite group showing a microgabbroic texture. The rock consists of pyroxene (52.0 - 58.2 vol%) - dominantly prismatic pigeonite (En60-68Fs20-27Wo7-9) associated with minor augite (En46-49Fs15-16Wo28-31) - brown (shock-oxidized) olivine (Fo65-69; 22.1 - 31%), completely isotropic interstitial plagioclase glass (maskelynite; An50-64Or0.3-0.9, 8.6 - 13.0%), chromite and titanian magnesian chromite (0.9 - 1.0%), traces of ilmenite (Ilm80-86), pyrrhotite (Fe92-100; 0.1 - 0.2%), merrillite (<< 0.1%), and pockets (4.8 - 6.7%) consisting of green basaltic to basaltic andesitic shock glass that is partially devitrified into a brown to black product along boundaries with the primary minerals. The average maximum dimensions of minerals are: olivine (1.5 mm), pyroxene (0.3 mm) and maskelynite (0.3 mm). Primary melt inclusions in olivine and chromite are common and account for 0.1 - 0.6% of the rock. X-ray tomography revealed that the specimen contains approximately 0.4 vol% of shock-melt associated vesicles, up to 3 mm in size, which show a preferred orientation. Fluidization of the maskelynite, melting and recrystallization of pyroxene, olivine and pyrrhotite indicate shock stage S6. Minor terrestrial weathering resulted in calcite-veining and minor oxidation of sulfides. The meteorite is interpreted as paired with SaU 005/008/051. The modal composition is similar to Dar al Gani 476/489/670/735/876, with the exception that neither mesostasis nor titanomagnetite nor apatite are present and that all phases show little zonation. The restricted mineral composition, predominance of chromite among the oxides, and abundance of olivine indicate affinities to the lherzolitic shergottites
Childhood vaccination coverage and regional differences in Swiss birth cohorts 2012–2021: Are we on track?
No full textAims
Many western countries are challenged by delayed and insufficient vaccination coverage rates in children, and thus missing WHO coverage targets. This study aimed to estimate vaccination coverage and timeliness in Swiss children over a decade. Furthermore, we evaluated the impact of COVID-19, regional variations, and the adherence to the amended vaccination schedule in 2019.
Methods
Retrospective observational study with Swiss health insurance claims data including birth cohorts 2012–2021 of children continuously observed until ages 13, 25, and 48 months respectively. We used population-weighted proportions and time-to-event analyses to describe coverage and timeliness of diphtheria/tetanus/pertussis/poliomyelitis/haemophilus influenzae type b (DTaP-IPV-Hib), measles/mumps/rubella (MMR), hepatitis B (HBV), pneumococcal (PCV), and meningococcal (MCV) vaccinations according to the national schedule. The potential impact of COVID-19 and vaccination schedule adherence were evaluated descriptively. Logistic regression was used to investigate regional factors potentially associated with non-vaccination.
Results
120,073 children, representing between 12 and 17 % of all Swiss children born in corresponding years, were included. Coverage remained stable or improved over the years. The 2019 amendment of the national immunization schedule was associated with an increase of ~10 % points in full coverage in Swiss children for DTaP-IPV-Hib, MMR and HBV despite the concurrent COVID-19 pandemic. Nonetheless, full vaccination coverage remained below 90 % with many vaccination series being delayed or not completed. The comparison across the different vaccines revealed large differences in coverage. Moreover, we observed large regional differences in non-vaccination with children living in rural and German-speaking areas more likely to be entirely unvaccinated.
Conclusion
Full vaccination coverage in Swiss children is still below 90 % with many vaccinations administered delayed. Given regional differences, missed or delayed booster vaccinations, and differences in vaccine-specific acceptability, more effort may be needed to achieve national vaccination targets
MoNa - a cost-efficient, portable system for the nanoinjection of living cells
No full textSimonis M, Sandmeyer A, Greiner J, Kaltschmidt B, Huser T, Hennig S. MoNa - a cost-efficient, portable system for the nanoinjection of living cells. Scientific reports. 2019;9(1): 5480.Injection techniques to deliver macromolecules to cells such as microinjection have been around for decades with applications ranging from probing whole organisms to the injection of fluorescent molecules into single cells. A similar technique that has raised recent interest is nanoinjection. The pipettes used here are much smaller and allow for the precise deposition of molecules into single cells via electrokinetics with minimal influence on the cells' health. Unfortunately, the equipment utilized for nanoinjection originates from scanning ion conductance microscopy (SICM) and is therefore expensive and not portable, but usually fixed to a specific microscope setup. The level of precision that these systems achieve is much higher than what is needed for the more robust nanoinjection process. We present Mobile Nanoinjection (MoNa), a portable, cost-efficient and easy to build system for the injection of single cells. Sacrificing unnecessary sub-nanometer accuracy and low ion current noise levels, we were able to inject single living cells with high accuracy. We determined the noise of the MoNa system and investigated the injection conditions for 16 prominent fluorescent labels and fluorophores. Further, we performed proof of concepts by injection of ATTO655-Phalloidin and MitoTracker Deep Red to living human osteosarcoma (U2OS) cells and of living adult human inferior turbinate stem cells (ITSC's) following neuronal differentiation with the MoNa system. We achieved significant cost reductions of the nanoinjection technology and gained full portability and compatibility to most optical microscopes
- …
