Myelin protein P0-specific IgM producing monoclonal B cell lines were established from polyneuropathy patients with monoclonal gammopathy of undetermined significance (MGUS)

Monoclonal expansion of B cells and plasma cells, producing antibodies against 'self' molecules, can be found not only in different autoimmune diseases, such as peripheral neuropathy (PN), but also in malignancies, such as Waldenström's macroglobulinaemia and B-type of chronic lymphocytic leukaemia (B-CLL), as well as in precancerous conditions including monoclonal gammopathy of undetermined significance (MGUS). About 50% of patients with PN-MGUS have serum antibodies against peripheral nerve myelin, but the specific role of these antibodies remains uncertain. The aims of the study were to establish, and characterize, myelin-specific B cell clones from peripheral blood of patients with PN-MGUS, by selection of cells bearing specific membrane Ig-receptors for myelin protein P0, using beads coated with P0. P0-coated magnetic beads were used for selection of cells, which subsequently were transformed by Epstein--Barr virus. The specificity of secreted antibodies was tested by ELISA. Two of the clones producing anti-P0 antibodies were selected and expanded. The magnetic selection procedure was repeated and new clones established. The cells were CD5+ positive, although the expression declined in vitro over time. The anti-P0 antibodies were of IgM-lambda type. The antibodies belonged to the VH3 gene family with presence of somatic mutations. The IgM reacted with P0 and myelin-associated glycoprotein (MAG), and showed no evidence for polyreactivity, in contrast to other IgM CD5+ clones included in the study as controls. The expanded clones expressed CD80 and HLA-DR, which is compatible with properties of antigen-presenting cells. The immunomagnetic selection technique was successfully used for isolation of antimyelin protein P0-specific clones. The cell lines may provide useful tools in studies of monoclonal gammopathies, leukaemia, and autoimmune diseases, including aspects of antigen-presentation by these cells followed by T cell activation.

Generalization of the normalized dose-response gradient to non-uniform dose delivery

A generalization of the standard dose-response gradient to arbitrarily heterogeneous dose distributions has been developed. The generalized dose-response gradient is the scalar product of the vector representing the dose distribution and the gradient of the dose-response relation with respect to that dose vector. It is shown that, for a tumor, the individual gamma-values for each portion of the tumor divided by the corresponding local tumor control probability should be added to get the total value for the heterogeneously irradiated tumor. This corresponds to summing up the contributions of all tumor volumes so that the total value of the gradient is related to the logarithm of the total tumor clonogen number. General expressions are also derived for the change in the dose-response relation as a function of a change in the delivered dose distribution.

Biologically optimized radiation therapy

Advanced treatment optimization is possible using quantitative radiobiological dose response models. Although all present models are necessarily linked to a certain degree of uncertainty, this will only have a small influence on the relative shape of the resultant optimal dose distribution. However the exact dose level should perferably be determined clinically by dose escalation with the optimized dose plan as a control arm. It is shown that a large part of the biological effect of high linear energy transfer radiation is due to the spectrum of low-energy delta-electrons that can generate dense clusters of complex DNA damage. Such electrons are efficiently generated by low-energy photons or densely ionizing ion beams and to a considerably smaller degree by high-energy electrons, photons and protons. A new analytical expression is developed for the effective radiation resistance of heterogeneous tumors, making it possible to approximate the response of such tumors by the effective clonogen number N0,eff and the effective D0 value D0,eff. It is shown that a relatively small number of resistant tumor cells may well be sufficient to dominate the response of hypoxic or otherwise heterogeneous tumors. Finally, several examples are given of intensity-modulated dose distributions generated by multiple radiation modalities, the total effect of which is biologically optimized.

Masked myoclonus in corticobasal degeneration: neurophysiological study of a case

A single case study of a 58 year-old male with right asymmetric apraxia and akinetic-rigid syndrome is described. Brainimaging scans (MRI, SPECT) indicated asymmetric cortical atrophy compatible with the diagnosis of Corticobasal Degeneration. Reflex myoclonus was absent and myoclonic discharges only appeared in response to pharmacological treatment of limb dystonia and rigidity. Electromyographic evidence of jerky movements was recorded only in the affected right hand and forearm after muscle relaxation, and myoclonus was not preceded by an EEG paroxysm. The cortical components of the correspondent SEPs were not increased in amplitude while LLRs recordings showed a late response over the muscles of the affected side. Furthermore, the duration of post MEP silent period was bilaterally reduced. This single case study report points out that sometimes myoclonus in Corticobasal Degeneration can be masked by the presence of increased muscle tone.

Cladding pumped Ytterbium-doped fiber laser with holey inner and outer cladding

We have fabricated an ytterbium doped all-glass double-clad large mode area holey fiber. A highly efficient cladding pumped single transverse mode holey fiber laser has been demonstrated, allowing continuous-wave output powers in excess of 1W with efficiencies of more than 80%. Furthermore both Q-switched and mode-locked operation of the laser have been demonstrated.

Microfluidic components for protein characterization

The use of microfluidic components to create an analytical toolbox for the very rapidly growing field of proteomics is described. This toolbox provides novel generic analytical solutions that are highly adaptable for analysis of various biomolecules, ranging from high to low abundant. The components are fabricated using silicon micromachining and consist of a microchip immobilised enzyme reactor (microIMER), a piezoelectric microdispenser and high-density nanovial target plates. This microtechnology based platform interfaces matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI TOF-MS) to a wide range of upstream sample handling and/or analytical techniques. Examples of applications such as rapid on-line digestion (12 s) and sample preparation of proteins, interfacing to capillary liquid chromatography (100 attomol sensitivity), and in-vial chemistry on femtomol amounts of sample are presented.

Identification of the origin of an Atlantic salmon (Salmo salar L.) population in a recently recolonized river in the Baltic Sea

The founder event in a recently recolonized salmon population in the Baltic Sea (Gulf of Finland) was investigated. To identify the origin of the founders, four wild populations and two hatchery stocks were analysed using six microsatellite loci. The results of assignment tests and factorial correspondence analysis suggest that the initial recolonizers of the river Selja originated from the geographically nearest (7 km) wild population (river Kunda) but as the result of stocking activities, interbreeding between recolonizers and hatchery individuals has occurred in subsequent years. Although the hatchery releases are outnumbering the wild salmon recruitment in the Baltic Sea at present, our results suggest that the native populations may still have an important role in colonization processes of the former salmon rivers.

A miniaturised electrochemical affinity assay based on a wall-free sample droplet and micro-dispensing of the redox-labelled binding partner

An affinity-assay was developed that is based on the modulation of the diffusion coefficient of a redox-labelled hapten upon complementary recognition of the analyte leading to an increase of molecular weight and hence to a decrease of the diffusion coefficient. The slower diffusion is monitored by means of cyclic voltammetry. In order to demonstrate the feasibility of this assay format, recognition of biotin by streptavidin has been chosen as a model system. Labelling of biotin was achieved by covalent binding of a ferrocene derivative to the biotin unit. To reduce the consumption of expensive compounds and to allow automatisation of the assay a novel miniaturised set-up was developed based on a wall-free sample droplet which forms the electrochemical cell with typical volumes of up to 10 microl. This droplet is dispensed by means of a step-motor driven syringe pump through a specially designed electrode holder spanning the gap between a micro-working electrode and a macroscopic counter electrode. By means of a piezo-driven micro-dispenser a predefined number of nano-droplets (100 pl volume each) containing the redox-labelled hapten are shot into the sample droplet. By this, any physical contact and hence any cross-contamination between the sample and the reagent solution could be avoided. Signal amplification can be achieved by redox recycling between the micro-electrode and the perpendicular positioned macroscopic counter electrode.

Increased rate of apoptosis in intimal arterial smooth muscle cells through endogenous activation of TNF receptors

Intimal proliferation of smooth muscle cells (SMCs) is a key event in the vascular response to injury, including the early stages of atherosclerosis and restenosis after angioplasty. Tumor necrosis factor-alpha (TNF-alpha) has been reported to stimulate growth of cultured human SMCs, but activation of TNF receptors is also known to induce cell death by apoptosis. We report here that SMCs isolated from the neointima of injured rat aortas are characterized by increased expression of TNF-alpha in response to interleukin-1beta and gamma-interferon compared with medial SMCs. Basal and serum-stimulated DNA synthesis was higher in intimal than in medial SMCs. In contrast to previous findings on human SMCs, exposure to interleukin-1beta/gamma-interferon or TNF-alpha did not affect the growth of rat medial SMCs, inhibited DNA synthesis, and decreased cell numbers in cultures of intimal SMCs. Incubation of intimal SMCs with these cytokines also resulted in induction of terminal dUTP nick end-labeling positivity and caspase-3 expression, suggesting cell death by apoptosis, whereas medial cells were markedly less sensitive in this respect. Cytokine-induced apoptosis in intimal cells was effectively inhibited by treatment with antibodies against TNF receptors. These findings suggest that endogenous activation of TNF receptors may represent a way to limit accumulation of SMCs in injured arteries. This mechanism may also be important in SMC death in advanced atherosclerotic plaques.

Picodroplet-deposition of enzymes on functionalized self-assembled monolayers as a basis for miniaturized multi-sensor structures

We are reporting on a novel approach for structured immobilisation of enzymes on gold surfaces modified with monolayers of functionalised alkylthiols. The formation of enzyme spots is achieved by shooting very small volumes of an appropriate enzyme solution (down to 100 pl) onto a thiol-monolayer modified gold surface using a micro-dispenser. Formation of enzyme patterns is obtained by moving the micro-dispenser relative to the modified gold surface using a micro-positioning device. Enzyme spots with typical lateral dimensions of 100 microm are obtained, but also, more complex structures, e.g. lines or meander structures, can be achieved by multiple droplets dispensed during the concomitant movement of the micro-dispenser. The first enzyme layer on top of the functionalised thiol-monolayer is subsequently covalently immobilised using either carbodiimide activation of carboxilic headgroups at the enzyme or via already introduced activated ester functions at the monolayer. Immobilised enzyme activities of glucose oxidase and lactate oxidase patterns have been characterised by means of scanning electrochemical microscopy. The product of the enzyme-catalysed reaction, H(2)O(2), is detected with an micro-electrode in the presence of either or both substrates, glucose and lactate, leading to a visualisation of the corresponding enzyme pattern and the lateral enzymatic activity.

CRM1 mediates the export of ADAR1 through a nuclear export signal within the Z-DNA binding domain

RNA editing of specific residues by adenosine deamination is a nuclear process catalyzed by adenosine deaminases acting on RNA (ADAR). Different promoters in the ADAR1 gene give rise to two forms of the protein: a constitutive promoter expresses a transcript encoding (c)ADAR1, and an interferon-induced promoter expresses a transcript encoding an N-terminally extended form, (i)ADAR1. Here we show that (c)ADAR1 is primarily nuclear whereas (i)ADAR1 encompasses a functional nuclear export signal in the N-terminal part and is a nucleocytoplasmic shuttle protein. Mutation of the nuclear export signal or treatment with the CRM1-specific drug leptomycin B induces nuclear accumulation of (i)ADAR1 fused to the green fluorescent protein and increases the nuclear editing activity. In concurrence, CRM1 and RanGTP interact specifically with the (i)ADAR1 nuclear export signal to form a tripartite export complex in vitro. Furthermore, our data imply that nuclear import of (i)ADAR1 is mediated by at least two nuclear localization sequences. These results suggest that the nuclear editing activity of (i)ADAR1 is modulated by nuclear export.

Endoscopic surveillance of columnar-lined esophagus: frequency of intestinal metaplasia detection and impact of antireflux surgery

OBJECTIVE

To quantify the occurrence of intestinal metaplasia in columnar-lined esophagus (CLE) during endoscopic surveillance and to evaluate the impact of antireflux surgery on the development of intestinal metaplasia.

SUMMARY BACKGROUND DATA

The malignant potential in segments of CLE is mainly restricted to those containing intestinal metaplasia. Patients with segments of CLE in which no intestinal metaplasia can be detected are rarely enrolled in a surveillance program but may still be at increased risk of developing esophageal adenocarcinoma because intestinal metaplasia may be missed or may develop with time.

METHODS

The occurrence of intestinal metaplasia on biopsy samples was determined on repeated endoscopies in 177 patients enrolled in a surveillance program for CLE. The incidence of intestinal metaplasia in patients with no evidence of intestinal metaplasia on the two first endoscopies was evaluated on the subsequent endoscopies and compared in patients with medically and surgically treated gastroesophageal reflux disease.

RESULTS

Intestinal metaplasia was found in 53% of the patients (94/177) on their first surveillance endoscopy and was more prevalent in long segments of CLE. The prevalence of intestinal metaplasia increased markedly with increasing number of surveillance endoscopies. Intestinal metaplasia tended to be detected early in patients with long segments of CLE; in patients with shorter segments, intestinal metaplasia was also detected late in the course of endoscopic surveillance. Patients with surgically treated reflux disease were 10.3 times less likely to develop intestinal metaplasia compared with a group receiving standard medical therapy.

CONCLUSION

Biopsy samples from a single endoscopy, despite an adequate biopsy protocol, are insufficient to rule out the presence of intestinal metaplasia. Patients in whom biopsy specimens from a segment of CLE show no intestinal metaplasia have a significant risk of having undetected intestinal metaplasia or of developing intestinal metaplasia with time. Sampling error is probably the reason for the absence of intestinal metaplasia in segments of CLE longer than 4 cm, whereas development of intestinal metaplasia is common in patients with shorter segments of CLE. Antireflux surgery protects against the development of intestinal metaplasia, possibly by better control of reflux of gastric contents.

Disposable polymeric high-density nanovial arrays for matrix assisted laser desorption/ionization-time of flight-mass spectrometry: I. Microstructure development and manufacturing

In order to meet the expected enormous demand for mass spectrometry (MS) throughput as a result of the current efforts to completely map the human proteome, this paper presents a new concept for low-cost high-throughput protein identification by matrix assisted laser desorption/ionization-time of flight-(MALDI-TOF)-MS peptide mapping using disposable polymeric high-density nanovial MALDI target plates. By means of microfabrication technology precision engineered nanovial arrays are fabricated in polymer substrates such as polymethylmethacrylate (PMMA) and polycarbonate (PC). The target plate fabrication processes investigated were precision micromilling, cold embossing and injection moulding (work in progress). Nanovial dimensions were 300, 400 or 500 microm. Typical array densities were 165 nanovials/cm2, which corresponds to 3,300 vials on a full Applied Biosystems MALDI target plate. Obtained MALDI data displayed equal mass resolution, accuracy, signal intensity for peptide standards as compared to high-density silicon nanovial arrays previously reported by our group [7], as well as conventional stainless steel or gold targets.

Involvement of p38-mitogen-activated protein kinase in Staphylococcus aureus-induced neutrophil apoptosis

Apoptosis occurred in human neutrophils within an hour of exposure to viable serum-opsonized Staphylococcus aureus, as indicated by appearance of cells with condensed nuclei, fragmented DNA, and increased phosphatidylserine exposure. In contrast, serum-opsonized, heat-killed S. aureus did not induce apoptosis. This discrepancy could not be explained by differences in bacterial uptake or total NADPH-oxidase activity. Suppressing phagocytosis by pretreating the neutrophils with cytochalasin b or by using nonopsonized bacteria did not prevent apoptosis. A supernatant from bacteria grown for 2 h in nutrient broth had a strong proapoptotic influence that was abrogated by heat treatment. Exposure to viable S. aureus or supernatant also led to activation of p38-mitogen-activated protein kinase in the neutrophils. Inhibition of this kinase with SB203580 reduced the apoptosis-inducing capacity of both bacteria and supernatant. We conclude that S. aureus activates p38-mitogen-activated protein kinase in neutrophils and induces apoptosis, probably mediated by a bacteria-derived soluble factor(s).

Disposable polymeric high-density nanovial arrays for matrix assisted laser desorption/ionization-time of flight-mass spectrometry: II. Biological applications

A novel disposable high-density matrix assisted laser desorption/ionization (MALDI) target plate made either from polymethylmethacrylate (PMMA) or polycarbonate (PC) is presented where thousands (1,200-1,600) of samples can be deposited and subsequently analyzed by MALDI-time of flight (TOF) mass spectrometry. Good reproducibility was obtained across the plate regardless of position on the target plate with a relative standard deviation (RSD) on the peak intensity of typically 30% calculated from data generated by analysis of a 10 nm peptide mixture of angiotensin I, II, III and bradykinin. The nanovial array format combined with microdispensing technology makes it possible to carry out in-vial chemistry on deposited samples. This is demonstrated by the analysis of peptides from beta-casein and subsequent in-vial dephosphorylation of its phosphopeptides at 10 fmol levels by microdispensing of alkaline phosphatase, into the nanovial. The mass spectra obtained from these polymeric targets provides can also be used in high sensitivity applications as shown by peptide mass fingerprinting of human fibroblast proteins separated by two-dimensional gel electrophoresis.

Downsizing proteolytic digestion and analysis using dispenser-aided sample handling and nanovial matrix-assisted laser/desorption ionization-target arrays

An efficient technique for enzymatic digestion of proteins in nanovial arrays and identification by peptide mass fingerprinting using matrix-assisted laser desorption/ionization (MALDI-MS) is presented in this work. Through dispensing of a protein solution with simultaneous evaporation the protein (substrate) is concentrated up to 300 times in-vial. At higher substrate concentrations the catalytic turnover numbers increase according to the Michaelis-Menten kinetics. Therefore, the dispenser-aided nanodigestion is valuable for identification of low-level proteins (10 nM-500 nM) as well as for automatic high efficiency digestions performed in 0.2-10 min. As an example of low-level protein identification, a 10 nM solution of lysozyme C was unambiguously identified after 5 min of nanodigestion. Moreover, only 30 s nanodigestion was sufficient to identify hemoglobin (10 microM), exemplifying the fast catalysis of the nanodigestion technique. The developed silicon flow-through piezoelectric dispenser is adapted for low-volume and preconcentrated samples in the nL-microL range and provides fast, accurate and contact-free sample positioning into the nanovials. In this work, the properties of the nanodigestion concept regarding proteins of different characteristics are explored. Furthermore, the potential of automated protein identification using precoated proteolytic nanovial-arrays is demonstrated.

Development of silicon microstructures and thin-film MALDI target plates for automated proteomics sample identifications

Here we report on the development of a proteomic platform utilizing a piezoelectric flow-through dispensing unit made from silicon microstructures. The use of a novel surface coating, where matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI MS) targets were uniformly precoated with a thin film of matrix/nitrocellulose, made the sample preparation straightforward and enabled the enrichment and analysis of proteins at low levels in proteomics samples. We demonstrate this by analyzing excised spots in a biological sample originating from a human fetal fibroblast cell line that was subjected to 2D gel-electrophoresis. Furthermore, a sample deposition rate below 30 Hz results in an increased analyte density on the dispensed sample spot, rendering signal amplification. In general, the sensitivity for proteins and peptides can be enhanced 10-50 times compared to traditional MALDI sample preparation techniques.

Emerging principles of de novo catalyst design

Considerable progress has been made in the understanding of how to exploit hydrophobic and charge-charge interactions in forming binding sites for peptides and small molecules in folded polypeptide catalysts. This knowledge has enabled the introduction of feedback and control functions into catalytic cycles and the construction of folded polypeptide catalysts that follow saturation kinetics. Major advances have also been made in the design of metalloproteins and metallopeptides, especially with regards to understanding redox potential control.

Cloning, characterization, and expression of human LIG1

Growth factor receptors are frequently amplified and over-expressed in various human cancers. Recently, a Drosophila cell surface protein, Kekkon-1, was found to participate in an epidermal growth factor (EGF) driven negative feedback loop. Kekkon-1 is induced by EGF, binds to the EGF-receptor, and inhibits receptor-mediated signaling. Here, we have searched for human genes with homologies to Kekkon-1 and identified human LIG1. The gene is the human homologue of mouse Lig-1 and is located on chromosome band 3p14, a region frequently deleted in various human cancers. It is predicted to encode a transmembrane cell-surface protein with extracellular leucine-rich repeats and immunoglobulin-like domains. LIG1 mRNA was detected in all tissues analyzed. The highest and lowest relative expression levels were found in brain and spleen, respectively, and differed by more than 200-fold. Taken together, our data are compatible with a role for LIG1 as a growth and tumor suppressor in human tissues.

Determination of diffusion coefficients of electroactive species in time-of-flight experiments using a microdispenser and microelectrodes

Two novel methods for the determination of diffusion coefficients of redox species combining the special properties of microdispensing devices and microelectrodes are presented. Both are based on the local application of tiny volumes of the redox-active species by means of a dispenser nozzle at a defined distance from the surface of a microelectrode. The microelectrode, which is inserted through the bottom into an electrochemical cell, is held at a constant potential sufficient to oxidize or reduce the electro-active species under diffusional control. The dispenser, which is filled with the electro-active species, can be positioned by means of micrometer screws over the microelectrode. After dispensing a defined number of droplets near the microelectrode surface, the current through the microelectrode is recorded, usually yielding a peak-shaped curve having a defined time delay between the shooting of the droplets and the maximum current. The time that is necessary to attain maximum current, together with the known distance between two dispensing points, can be used to determine the diffusion coefficient of the electroactive species without knowledge of any system parameters, such as concentration of the redox species, diameter of the electroactive surface or number of transferred electrons. A similar method for the determination of diffusion coefficient of redox species involves a second redox species for calibration purposes. A mixture of both species is shot close to the microelectrode surface. Due to the different formal potentials of the redox species that are used, they can be distinguished in sequential experiments by variation of the potentials that are applied to the microelectrode, and it is thus possible to determine the individual transit times of the redox species independently. The difference in the transit times, together with the known diffusion coefficient of one of the redox species, can be used to calculate the unknown diffusion coefficient of the second one.