LIGHT-SABRE Hyperpolarizes 1-13C-Pyruvate Continuously without Magnetic Field Cycling

Nuclear spin hyperpolarization enables real-time observation of metabolism and intermolecular interactions in vivo. 1-¹³C-pyruvate is the leading hyperpolarized tracer currently under evaluation in several clinical trials as a promising molecular imaging agent. Still, the quest for a simple, fast, and efficient hyperpolarization technique is ongoing. Here, we describe that continuous, weak irradiation in the audio-frequency range of the ¹³C spin at the 121 μT magnetic field (approximately twice Earth's field) enables spin order transfer from parahydrogen to ¹³C magnetization of 1-¹³C-pyruvate. These so-called LIGHT-SABRE pulses couple nuclear spin states of parahydrogen and pyruvate via the J-coupling network of reversibly exchanging Ir-complexes. Using ∼100% parahydrogen at ambient pressure, we polarized 51 mM 1-¹³C-pyruvate in the presence of 5.1 mM Ir-complex continuously and repeatedly to a polarization of 1.1% averaged over free and catalyst-bound pyruvate. The experiments were conducted at -8 °C, where almost exclusively bound pyruvate was observed, corresponding to an estimated 11% polarization on bound pyruvate. The obtained hyperpolarization levels closely match those obtained via SABRE-SHEATH under otherwise identical conditions. The creation of three different types of spin orders was observed: transverse ¹³C magnetization along the applied magnetic field, ¹³C z-magnetization along the main field B ₀, and ¹³C-¹H zz-spin order. With a superconducting quantum interference device (SQUID) for detection, we found that the generated spin orders result from ¹H-¹³C J-coupling interactions, which are not visible even with our narrow linewidth below 0.3 Hz and at -8 °C.

Evaluation of crotamine based probes as intracellular targeted contrast agents for magnetic resonance imaging

Crotamine is a lysine and cysteine rich 42 amino acids long bio-active polypeptide, isolated from the venom of a South American rattlesnake, that can also be used as cell penetrating peptide. A facile synthetic scheme for coupling cargo molecules like fluorophores (carboxyfluorescein) or MRI probes (Gd-DO3A-based macrocycle) is presented. The toxicity, cellular internalization and steady-state accumulation after long-term incubation for 18 h, as well as magnetic resonance relaxivities and cellular relaxation rates of crotamine based probes were evaluated and compared to its shorter synthetic fragment CyLoP-1. The longitudinal relaxivity (r₁) of the conjugates of CyLoP-1 and crotamine is significantly lower in medium than in water indicating to the lower contrast enhancement efficacy of DO3A-based probes in biological samples. Carboxyfluorescein labeled crotamine did not exhibit toxicity up to a concentration of 2.5 µM. CyLoP-1 accumulated about four times better within the cells compared to crotamine. Fluorescence microscopy suggests different predominant uptake mechanisms for crotamine and CyLoP-1 in 3T3 cells. While crotamine is predominantly localized in vesicular structures (most likely endosomes and lysosomes) within the cell, CyLoP-1 is mainly homogeneously distributed in the cytosol. The cellular relaxation rate (R_{1, cell}) of the crotamine based probe was not significantly increased whereas the corresponding CyLoP-1-derivative showed a slightly elevated R_{1, cell}. This study indicates the potential of crotamine and in particular the shorter fragment CyLoP-1 to be useful for an efficient transmembrane delivery of agents directed to intracellular (cytosolic) targets. However, the applicability of the conjugates synthesized here as contrast agents in MR imaging is limited. Further improvement is needed to prepare more efficient probes for MRI applications, i.e., by replacing the DO3A- with a DOTA-based chelate.

Direct study of structural phase transformation in single crystalline bulk and thin film BaFe2As2

The ternary iron arsenide compound BaFe₂As₂ exhibits a structural phase transition from tetragonal to orthorhombic at a temperature of about 140 K. The twin lamellae arising below this transition temperature were studied in undoped single crystalline bulk and epitaxial thin film samples using electron backscatter diffraction in a scanning electron microscope equipped with a helium cryostat. Applying this technique on bulk single crystals a characteristic twin lamella size in the range of 0.1 μm up to a few μm was observed. In contrast, in epitaxially strained thin films the phase transition is not observed at temperatures above 19 K.

Reduced Complications during Hemodialysis by Automatic Blood Volume Controlled Ultrafiltration

Background

Intradialytic morbid events (IMEs, mostly hypotension) are frequent complications during hemodialysis (HD). This study investigated whether automatic feedback control via adjustment of the ultrafiltration rate reduces IME frequency.

Methods

In this multi-center cross-over study, 56 hypotension-prone patients were treated both with standard HD (sHD, applying a constant ultrafiltration rate) and HD applying a blood volume controlled ultrafiltration rate (cHD). The relative blood volume (RBV) was continuously monitored. The individual relative blood volume limit (RBVcrit) was determined from the measured RBV during initial sHD. During cHD, the ultrafiltration rate was automatically adjusted to keep the actual RBV above RBVcrit.

Results

In 3,081 HD treatments, slightly fewer IMEs were observed during cHD than during sHD (0.785±0.613 versus 0.695±0.547 per treatment, P=0.144). Less symptomatic events were seen during cHD: -13% for symptomatic hypotension (0.594 versus 0.685 per treatment, P=0.120), and -32% for cramps (0.049 versus 0.072 per treatment, P=0.009). Thirty-one patients with the highest IME rate (IME in at least every second treatment) especially benefited from cHD: 1.185±0.554 versus 0.979±0.543 IME per treatment (P=0.004). The reduction in blood pressure (BP) and the increase in heart rate were lower during the treatments with cHD than with sHD: systolic BP: -18.8±26.7 versus -22.2±28.9 mmHg (P=0.007), diastolic BP: -7.8±14.8 versus -9.1±15.3 mmHg (P=0.064), heart rate: 1.8±10.4 versus 2.3±11.6 per minute (P=0.014). Neither treatment duration nor ultrafiltration volume was significantly different between cHD and sHD.

Conclusion

For cHD, less intradialytic morbid events were observed than for sHD, and pre- to post-dialytic changes in blood pressure and heart rate were less pronounced.

Germinal Center B Cell-Like (GCB) and Activated B Cell-Like (ABC) Type of Diffuse Large B Cell Lymphoma (DLBCL): Analysis of Molecular Predictors, Signatures, Cell Cycle State and Patient Survival

Aiming to find key genes and events, we analyze a large data set on diffuse large B-cell lymphoma (DLBCL) gene-expression (248 patients, 12196 spots). Applying the loess normalization method on these raw data yields improved survival predictions, in particular for the clinical important group of patients with medium survival time. Furthermore, we identify a simplified prognosis predictor, which stratifies different risk groups similarly well as complex signatures.

We identify specific, activated B cell-like (ABC) and germinal center B cell-like (GCB) distinguishing genes. These include early (e.g. CDKN3) and late (e.g. CDKN2C) cell cycle genes.

Independently from previous classification by marker genes we confirm a clear binary class distinction between the ABC and GCB subgroups. An earlier suggested third entity is not supported. A key regulatory network, distinguishing marked over-expression in ABC from that in GCB, is built by: ASB13, BCL2, BCL6, BCL7A, CCND2, COL3A1, CTGF, FN1, FOXP1, IGHM, IRF4, LMO2, LRMP, MAPK10, MME, MYBL1, NEIL1 and SH3BP5. It predicts and supports the aggressive behaviour of the ABC subgroup. These results help to understand target interactions, improve subgroup diagnosis, risk prognosis as well as therapy in the ABC and GCB DLBCL subgroups.

Importance of chewing, saliva, and swallowing function in patients with advanced oral cancer undergoing preoperative chemoradiotherapy: a prospective study of quality of life

The primary objective of this study was to investigate the quality of life (QOL) of patients with oral squamous cell carcinoma (OSCC) undergoing curative neoadjuvant chemoradiotherapy followed by radical tumour resection and simultaneous oral cavity reconstruction, using two validated questionnaires. A secondary objective was to assess clinical variables predicting post-treatment dysfunction in chewing, saliva, and swallowing. Thirty-five patients with locally advanced OSCC who underwent preoperative chemoradiotherapy were recruited prospectively. All patients completed both the University of Washington Quality of Life version 4 questionnaire (UW-QOL) and the Functional Assessment of Cancer Therapy-Head & Neck version 4 questionnaire (FACT-H&N). UW-QOL and FACT-H&N items were associated with clinical variables. Nearly three-quarters of OSCC patients perceived good to excellent levels of overall QOL after preoperative chemoradiotherapy. Chewing difficulties, decreased salivary function, and swallowing dysfunction were the most frequent complaints of OSCC patients. Items related to food intake were significantly worse in OSCC patients older than 60 years and those with T4 tumours, as well as those without alcohol intake. Chewing, saliva, and swallowing are the most significant issues in patients with OSCC undergoing preoperative chemoradiotherapy. The results of this study may help guide treatment decisions for OSCC patients based on more accurate expectations of adverse effects of cancer treatment.

A quest for excitation: Theoretical arguments and immunohistochemical evidence of excitatory granular cells in the ELL of Gnathonemus petersii

The Electrosensory Lateral Line lobe (ELL) is the first central target where the electrosensory information encoded in the spatiotemporal pattern electroreceptor afferent discharges is processed. These afferents encode the minute amplitude changes of the basal electric field through both a change in latency and discharge rate. In the ELL the time and rate-coded input pattern of the sensory periphery goes through the granular cell layer before reaching the main efferent cells of the network: large fusiform (LF) and large ganglion (LG) cells. The evidence until now shows that granular cells are inhibitory. Given that large fusiform cells are excited by the sensory input, it remains a mystery how the afferent input produce excitation through a layer composed by only inhibitory cells. We addressed this problem by modeling how the known circuitry of the ELL could produce excitation in LF cells with only inhibitory granular cells. Alternatively we show that a network composed of a mix of excitatory and inhibitory granular cell not only performs better, as expected, carrying excitation to LF cells but it does so robustly and at higher sensitivity by enhancing the contrast of the electric image between the periphery and the ELLs output. We then show with refined histological methods that a subpopulation of the granular cells indeed are excitatory, providing the necessary input for this contrast enhancing mechanism.

Prognostic role of pretreatment plasma fibrinogen in patients with solid tumors: A systematic review and meta-analysis

BACKGROUND

Plasma fibrinogen may be involved in several stages of cancer progression. Clinical studies have demonstrated that pretreatment plasma fibrinogen is associated with poor survival in various cancers. The aim of this meta-analysis was to examine the prognostic effect of circulating fibrinogen in solid tumors.

MATERIALS AND METHODS

We searched Medline, EMBASE, Cochrane Database of Systematic Reviews, and meeting proceedings to identify studies assessing the effect of pretreatment plasma fibrinogen on survival of cancer patients. Pooled multivariable-adjusted hazard ratios (HRs) for overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS) were estimated using random-effects models.

RESULTS

Data from 52 observational studies and 15,371 patients were summarized. An elevated baseline plasma fibrinogen was significantly associated with worse OS (pooled HR = 1.69; 95% CI = 1.48–1.92). The highest negative effect of elevated plasma fibrinogen on OS was demonstrated in renal cell carcinoma (pooled HR = 2.22), followed by head and neck cancer (pooled HR = 2.02), and colorectal cancer (pooled HR = 1.89). The adverse prognostic impact of high plasma fibrinogen remained in both non-metastatic and metastatic disease and patients of different ethnicity. Patients with high baseline fibrinogen had a significantly shorter DFS (pooled HR = 1.52) and CSS (pooled HR = 2.50).

CONCLUSIONS

An elevated pretreatment plasma fibrinogen significantly correlates with decreased survival in patients with solid tumors. Future clinical trials are warranted to determine whether plasma fibrinogen could be incorporated in cancer staging systems and whether fibrinogen-lowering therapies have a favorable effect on disease recurrence and mortality.

Abnormal brain responses to social fairness in depression: an fMRI study using the Ultimatum Game

BACKGROUND

Depression is a prevalent disorder that significantly affects the social functioning and interpersonal relationships of individuals. This highlights the need for investigation of the neural mechanisms underlying these social difficulties. Investigation of social exchanges has traditionally been challenging as such interactions are difficult to quantify. Recently, however, neuroeconomic approaches that combine multiplayer behavioural economic paradigms and neuroimaging have provided a framework to operationalize and quantify the study of social interactions and the associated neural substrates.

METHOD

We investigated brain activation using functional magnetic resonance imaging (fMRI) in unmedicated depressed participants (n = 25) and matched healthy controls (n = 25). During scanning, participants played a behavioural economic paradigm, the Ultimatum Game (UG). In this task, participants accept or reject monetary offers from other players.

RESULTS

In comparison to controls, depressed participants reported decreased levels of happiness in response to 'fair' offers. With increasing fairness of offers, controls activated the nucleus accumbens and the dorsal caudate, regions that have been reported to process social information and responses to rewards. By contrast, participants with depression failed to activate these regions with increasing fairness, with the lack of nucleus accumbens activation correlating with increased anhedonia symptoms. Depressed participants also showed a diminished response to increasing unfairness of offers in the medial occipital lobe.

CONCLUSIONS

Our findings suggest that depressed individuals differ from healthy controls in the neural substrates involved with processing social information. In depression, the nucleus accumbens and dorsal caudate may underlie abnormalities in processing information linked to the fairness and rewarding aspects of other people's decisions.

Microscopic visualization of metabotropic glutamate receptors on the surface of living cells using bifunctional magnetic resonance imaging probes

A series of bimodal metabotropic glutamate-receptor targeted MRI contrast agents has been developed and evaluated, based on established competitive metabotropic Glu receptor subtype 5 (mGluR5) antagonists. In order to directly visualize mGluR5 binding of these agents on the surface of live astrocytes, variations in the core structure were made. A set of gadolinium conjugates containing either a cyanine dye or a fluorescein moiety was accordingly prepared, to allow visualization by optical microscopy in cellulo. In each case, surface receptor binding was compromised and cell internalization observed. Another approach, examining the location of a terbium analogue via sensitized emission, also exhibited nonspecific cell uptake in neuronal cell line models. Finally, biotin derivatives of two lead compounds were prepared, and the specificity of binding to the mGluR5 cell surface receptors was demonstrated with the aid of their fluorescently labeled avidin conjugates, using both total internal reflection fluorescence (TIRF) and confocal microscopy.

Magnetic resonance and optical imaging probes for NMDA receptors on the cell surface of neurons: synthesis and evaluation in cellulo

A second generation of N-methyl-d-aspartate (NMDA) receptor-targeted MRI contrast agents has been synthesised, based on bicyclic NMDA receptor antagonists and show selective and reversible cell-surface binding.

Facile synthesis of peptide nucleic acids and peptide nucleic acid-peptide conjugates on an automated peptide synthesizer

Peptide nucleic acids (PNAs) are DNA mimics with a neutral peptide backbone instead of the negatively charged sugar phosphates. PNAs exhibit several attractive features such as high chemical and thermal stability, resistance to enzymatic degradation, and stable binding to their RNA or DNA targets in a sequence-specific manner. Therefore, they are widely used in molecular diagnosis of antisense-targeted therapeutic drugs or probes and in pharmaceutical applications. However, the main hindrance to the effective use of PNAs is their poor uptake by cells as well as the difficult and laborious chemical synthesis. In order to achieve an efficient delivery of PNAs into cells, there are already many published reports of peptides being used for transport across the cell membrane. In this protocol, we describe the automated as well as cost-effective semi-automated synthesis of PNAs and PNA-peptide constructs on an automated peptide synthesizer. The facile synthesis of PNAs will be helpful in generating PNA libraries usable, e.g. for high-throughput screening in biomolecular studies. Efficient synthetic schemes, the automated procedure, the reduced consumption of costly reagents, and the high purity of the products are attractive features of the reported procedure.

Coding of Stimuli by Ampullary Afferents in Gnathonemus petersii

Weakly electric fish use electroreception for both active and passive electrolocation and for electrocommunication. While both active and passive electrolocation systems are prominent in weakly electric Mormyriform fishes, knowledge of their passive electrolocation ability is still scarce. To better estimate the contribution of passive electric sensing to the orientation toward electric stimuli in weakly electric fishes, we investigated frequency tuning applying classical input-output characterization and stimulus reconstruction methods to reveal the encoding capabilities of ampullary receptor afferents. Ampullary receptor afferents were most sensitive (threshold: 40 μV/cm) at low frequencies (<10 Hz) and appear to be tuned to a mix of amplitude and slope of the input signals. The low-frequency tuning was corroborated by behavioral experiments, but behavioral thresholds were one order of magnitude higher. The integration of simultaneously recorded afferents of similar frequency-tuning resulted in strongly enhanced signal-to-noise ratios and increased mutual information rates but did not increase the range of frequencies detectable by the system. Theoretically the neuronal integration of input from receptors experiencing opposite polarities of a stimulus (left and right side of the fish) was shown to enhance encoding of such stimuli, including an increase of bandwidth. Covariance and coherence analysis showed that spiking of ampullary afferents is sufficiently explained by the spike-triggered average, i.e., receptors respond to a single linear feature of the stimulus. Our data support the notion of a division of labor of the active and passive electrosensory systems in weakly electric fishes based on frequency tuning. Future experiments will address the role of central convergence of ampullary input that we expect to lead to higher sensitivity and encoding power of the system.

The electric organ discharges of the Petrocephalus species (Teleostei: Mormyridae) of the Upper Volta system

In this study, a first comparative investigation of all four species of Petrocephalus (P. bovei, P. bane, P. soudanensis and P. cf. pallidomaculatus) present in the Upper Volta system and their electric organ discharges (EOD) was conducted. It was found that P. bovei was the most widespread (in terms of habitat use), but in several places P. bovei, P. soudanensis and P. cf. pallidomaculatus occurred syntopically. All species emitted a triphasic signal, and with very few exceptions, the Petrocephalus species of the Upper Volta system could clearly be identified on the basis of their EOD waveforms. The most obvious differences between species in EOD waveforms were in amplitude of the last phase, total duration and fast Fourier transformation (FFT) peak frequency. No sexual dimorphism was present in the EOD of any species although external dimorphism, i.e. an indentation at the base of the anal fin of mature males, was common. The EOD waveform diversity in the Upper Volta principally resembled that found in four sympatric Petrocephalus species from the Ogooué system (Gabon) and might play a role in species recognition and speciation processes.

Dendritic backpropagation and synaptic plasticity in the mormyrid electrosensory lobe

This study is concerned with the origin of backpropagating action potentials in GABAergic, medium ganglionic layer neurones (MG-cells) of the mormyrid electrosensory lobe (ELL). The characteristically broad action potentials of these neurones are required for the expression of spike timing dependent plasticity (STDP) at afferent parallel fibre synapses. It has been suggested that this involves active conductances in MG-cell apical dendrites, which constitute a major component of the ELL molecular layer. Immunohistochemistry showed dense labelling of voltage gated sodium channels (VGSC) throughout the molecular layer, as well as in the ganglionic layer containing MG somata, and in the plexiform and upper granule cell layers of ELL. Potassium channel labelling was sparse, being most abundant in the deep fibre layer and the nucleus of the electrosensory lobe. Intracellular recordings from MG-cells in vitro, made in conjunction with voltage sensitive dye measurements, confirmed that dendritic backpropagation is active over at least the inner half of the molecular layer. Focal TTX applications demonstrated that in most case the origin of the backpropagating action potentials is in the proximal dendrites, whereas the small narrow spikes also seen in these neurones most likely originate in the axon. It had been speculated that the slow time course of membrane repolarisation following the broad action potentials was due to a poor expression of potassium channels in the dendritic compartments, or to their voltage- or calcium-sensitive inactivation. However application of TEA and 4AP confirmed that both A-type and delayed rectifying potassium channels normally contribute to membrane repolarisation following dendritic and axonal spikes. An alternative explanation for the shape of MG action potentials is that they represent the summation of active events occurring more or less synchronously in distal dendrites. Coincidence of backpropagating action potentials with parallel fibre input produces a strong local depolarisation that could be sufficient to cause local secretion of GABA, which might then cause plastic change through an action on presynaptic GABA(B) receptors. However, STP depression remained robust in the presence of GABAB receptor antagonists.

Germinal center B cell-like (GCB) and activated B cell-like (ABC) type of diffuse large B cell lymphoma (DLBCL): analysis of molecular predictors, signatures, cell cycle state and patient survival

Aiming to find key genes and events, we analyze a large data set on diffuse large B-cell lymphoma (DLBCL) gene-expression (248 patients, 12196 spots). Applying the loess normalization method on these raw data yields improved survival predictions, in particular for the clinical important group of patients with medium survival time. Furthermore, we identify a simplified prognosis predictor, which stratifies different risk groups similarly well as complex signatures. We identify specific, activated B cell-like (ABC) and germinal center B cell-like (GCB) distinguishing genes. These include early (e.g. CDKN3) and late (e.g. CDKN2C) cell cycle genes. Independently from previous classification by marker genes we confirm a clear binary class distinction between the ABC and GCB subgroups. An earlier suggested third entity is not supported. A key regulatory network, distinguishing marked over-expression in ABC from that in GCB, is built by: ASB13, BCL2, BCL6, BCL7A, CCND2, COL3A1, CTGF, FN1, FOXP1, IGHM, IRF4, LMO2, LRMP, MAPK10, MME, MYBL1, NEIL1 and SH3BP5. It predicts and supports the aggressive behaviour of the ABC subgroup. These results help to understand target interactions, improve subgroup diagnosis, risk prognosis as well as therapy in the ABC and GCB DLBCL subgroups.

Synthesis and cellular uptake of a MR contrast agent coupled to an antisense peptide nucleic acid--cell- penetrating peptide conjugate

In order to image mRNA transcription by in vivo magnetic resonance imaging (MRI), two intracellular MR contrast agents were developed, which are composed of a Gd-DOTA complex, a peptide nucleic acid (PNA) sequence and a cell-penetrating peptide. One was designed to bind to mRNA of dsRed (red fluorescent protein originating from Discosoma coral) by its PNA sequence, whereas the second one contains a nonsense sequence with no natural counterpart. The conjugates were synthesized using a continuous solid-phase synthesis scheme and characterized by ESI-MS. Fluorescence studies showed that both contrast agents could enter efficiently into 3T3 cells in a concentration-dependent manner from 0.5 to 9.0 microM. The contrast agent was located predominantly in vesicles around the nucleus, whereas no uptake into the nucleus was observed. The results of in vitro MR studies showed a statistically significant increase of the intracellular relaxation rate R (1,cell) at a labeling concentration of only 0.5 microM, thus contrast enhancement was detectable too. These results suggest that the synthesized contrast agents could label cells for optical as well as MR imaging and in future might be useful to prove specific accumulation in cells containing target mRNA.

Effects of three resin monomers on the cellular glutathione concentration of cultured human gingival fibroblasts

OBJECTIVES

Oral and systemic cells are permanently exposed to various types of xenobiotics, such as dental restorative materials, which may subsequently cause adverse effects. Objective of the present investigation was to analyze the effects of three important resin monomers on the glutathione metabolism of human gingival fibroblasts after an incubation period of 4h.

METHODS

Cells were exposed to various concentrations of 2-hydroxyethyl methacrylate (HEMA; 0.1-10 mM), triethylene-glycol dimethacrylate (TEGDMA; 0.05-2.5 mM), and urethane dimethacrylate (UDMA; 0.005-0.25 mM). Subsequently, cellular glutathione (GSH) concentrations were determined after a treatment period of 4h using the monobromobimane assay. Data were statistically evaluated using Tukey ANOVA with p<0.05.

RESULTS

GSH depletion was dependent on the type of the resin monomer: UDMA>TEGDMA>HEMA. The concentrations for a 50%-reduction of cellular GSH varied between 0.1 mM (0.05 mM) (UDMA), 0.33 mM (0.09 mM) (TEGDMA), and 1.6 mM (0.8 mM) (HEMA). Simultaneously, no decrease of cell numbers was found at any tested concentration.

SIGNIFICANCE

These data indicate that the investigated resins may cause cell damage due to depletion of intracellular GSH level even at low concentrations within a short period of time. The decrease of GSH is an early reaction, which is triggered prior to other cytotoxic alterations.

Zygocactus virus X-based expression vectors and formation of rod-shaped virus-like particles in plants by the expressed coat proteins of Beet necrotic yellow vein virus and Soil-borne cereal mosaic virus

Expression vectors were constructed from 35S promoter-containing full-length cDNA clones of Zygocactus virus X (ZVX). The expression of foreign genes was driven by the ZVX coat protein (cp) subgenomic promoter. It was successful only when the variable region downstream of the conserved putative promoter region GSTTAAGTT(X(12-13))GAA was retained. Most of the ZVX cp gene, except for a short 3' part, was replaced by the corresponding sequence of the related Schlumbergera virus X (SVX) and its cp subgenomic promoter to enable encapsidation of the transcribed RNA by an SVX/ZVX hybrid cp. Vector-expressed cp of Beet necrotic yellow vein virus (BNYVV) assembled in Chenopodium quinoa, Tetragonia expansa and Beta vulgaris leaves into particles resembling true BNYVV particles. The virus produced from these constructs retained its ability to express BNYVV cp in local infections during successive passages on C. quinoa. This ability was lost, however, in the rarely occurring systemic infections.

ROS formation and glutathione levels in human oral fibroblasts exposed to TEGDMA and camphorquinone

Glutathione (GSH) is important for the self-protection of cells against oxidative stress and toxic xenobiotics, whereas reactive oxygen species (ROS) at elevated concentrations may cause detrimental alterations of cell membranes, DNA, and other cellular structures. The present investigation addressed the effects of triethylene-glycoldimethacrylate (TEGDMA) and camphorquinone (CQ) on glutathione metabolism and the formation of ROS in oral cells. Primary human pulp fibroblasts were exposed to various concentrations of TEGDMA and CQ (0.1-5 mM). Subsequently, GSH concentration and ROS formation were analyzed with the use of the monobromobimane assay (GSH) and 2',7'-dichlorofluorescein diacetate (DCFH-DA) (ROS). The endogenous ROS hydrogen peroxide (H2O2) was used as a positive control (0.02-2 mM). TEGDMA significantly decreased GSH at concentrations between 0.5 and 5 mM (p<0.05), but did not elevate ROS levels. Contrary, CQ increased ROS formation at concentrations>or=1 mM, but had only a moderate effect on GSH at the highest test concentration. Hydrogen peroxide increased ROS and simultaneously decreased GSH at concentrations of >or=0.2 mM. These data show that the investigated substances may cause cell damage due to various mechanisms, GSH decrease and/or ROS increase. As a consequence, TEGDMA and CQ released into an aqueous environment from resinous materials might interact, thus generating significant cytotoxic effects even at low concentrations.

Effects of BisGMA on glutathione metabolism and apoptosis in human gingival fibroblasts in vitro

Aim of this study was to investigate the effects of the resin monomer BisGMA on the glutathione concentration (monobromobimane assay) and apoptosis (Annexin V/PI-assay) of cultured primary human gingival fibroblasts. Cells were treated for up to 24h with 0.001-0.25 mM BisGMA to determine growth curves using the DNA stain H33342. Subsequent Annexin V/PI-assays revealed that fibroblasts exposed to concentrations of 0.005-0.01 mM (non-cytotoxic) and 0.05 mM (ED(10)-concentration) showed no increase of the share of apoptotic cells compared to non-treated controls (5-8%), while 0.1 mM BisGMA (approximately ED(50)-concentration) caused a significant increase of the percentage of apoptotic cells (50%). Simultaneously to the induction of apoptosis, 0.1 and 0.25 mM of BisGMA caused a significant depletion of the intracellular GSH content after 18 h of incubation. Our results indicate that BisGMA at concentrations >0.1 mM causes an extreme depletion of the intracellular GSH pool as well as apoptosis.

Effect of TEGDMA on the intracellular glutathione concentration of human gingival fibroblasts

Previous studies revealed that primarily small and relatively hydrophilic comonomers, such as TEGDMA, leach out of resin-based restorative materials into aqueous media. Subsequently, these compounds may cause detrimental reactions with intracellular metabolic systems. The present experiments attempted to elucidate the interactions of TEGDMA with the important intracellular reducing agent glutathione (GSH). The influence of various concentrations of TEGDMA (0.5-7.5 mM) on viability and intracellular GSH concentration of primary human gingival fibroblasts was determined by means of a fluorescence assay (monobromobimane) performed in microtiter plates. Cells were treated with TEDGMA between 2 and 24 h. The incubation of fibroblasts with TEGDMA even at subtoxic concentrations quickly decreased the intracellular glutathione level to 30-50% of controls within the first 2-6 hours. However, no simultaneous adverse effect on cell viability was found. Longer incubation periods up to 24 h caused a regulatory reincrease at TEGDMA concentrations <or= 2.5 mM, whereas higher concentrations resulted in a continuous depletion of glutathione concentration concomitant with a significant decrease of cell viability. Because glutathione plays an important role in protection and detoxification processes as well in the regulation of cell death, the early and extensive depletion of the intracellular glutathione pool due to TEGDMA may significantly contribute to the cytotoxic potency of this compound.

Lateral line reception in still- and running water

The lateral line of fish is composed of neuromasts used to detect water motions. Neuromasts occur as superficial neuromasts on the skin and as canal neuromasts in subepidermal canals. Fibres of the lateral line nerves innervate both. There have been extensive studies on the responses of lateral line nerve fibres to dipole stimuli applied in still water. However, despite the fact that many fish live in rivers and/or swim constantly, responses of lateral line nerve fibres to dipole stimuli presented in running water have never been recorded. We investigated how the peripheral lateral line of still water fish ( Carassius auratus) and riverine fish ( Oncorhynchus mykiss) responds to minute sinusoidal water motions while exposed to unidirectional water flow. Both goldfish and trout have two types of posterior lateral line nerve fibres: Type I fibres, which most likely innervate superficial neuromasts, were stimulated by running water (10 cm s(-1)). The responses of type I fibres to water motions generated by a vibrating sphere were masked if the fish was exposed to running water. Type II fibres, which most likely innervate canal neuromasts, were not stimulated by running water. Consequently, responses of type II fibres to a vibrating sphere were not masked under flow conditions.

Metabolic effects of dental resin components in vitro detected by NMR spectroscopy

Earlier studies have shown that the comonomer triethyleneglycol-dimethacrylate (TEGDMA) and the photostabilizer 2-hydroxy-4-methoxybenzophenone (HMBP) are cytotoxic and inhibit cell growth. It was the aim of this study to elucidate the underlying metabolic effects of TEGDMA and HMBP on immortal contact-inhibited Swiss albino mouse embryo cells (3T3 fibroblasts) by nuclear magnetic resonance (NMR) spectroscopy. Cell extracts and culture media were analyzed by NMR spectroscopy for metabolic changes after incubation for 24 hours with ED20-concentrations of TEGDMA and HMBP. TEGDMA could be detected in all fractions (cytosol, lipid fractions, and culture media) of 3T3 cells, while HMBP was found only in the lipid fraction accumulated at a maximum rate (51 nmol/mg DNA) compared with TEGDMA (27 nmol/mg DNA). TEGDMA increased the concentration of phosphomonoesters to 180+/-36% and decreased the phosphodiesters to 65+/-5% of controls (control = 100%). Thus, the turnover of phospholipids was enhanced, whereas content and composition of phospholipids of membranes did not alter markedly. Additionally, TEGDMA changed the metabolic state of cells, indicated by slight decreases of nucleoside triphosphates and an increase in the ratio of nucleoside diphosphates to nucleoside triphosphates, while HMBP had no effect. The most remarkable effect of TEGDMA was a nearly complete decline of the intracellular glutathione levels. Analysis of our data shows that NMR spectroscopy of cell-material interactions may reveal metabolic effects of organic test substances which are not detectable by standard in vitro assays. The comonomer TEGDMA affected the metabolism of the cells on different levels, while HMBP accumulated in the lipid fraction and induced significantly fewer effects on cell metabolism.

Changes of intracellular calcium, fatty acids and phospholipids during miltefosine-induced apoptosis monitored by fluorescence- and 13C NMR-spectroscopy

The alkylphosphocholine Miltefosine (hexadecylphosphocholine, HePC) induces apoptosis in human epithelial KB cells, whereas no such effect can be observed in a resistant clone (KBres). Its mode of action is mediated via the cell membrane, whereas the mechanism is still widely unknown. The use of various spectroscopic methods (fluorescence spectroscopy with Fura-2/AM on viable cells, 13C NMR spectroscopy on lipid extracts) reveals osmotic and metabolic changes in HePC treated sensitive cells. Intracellular free Ca(2+)-concentration increased over 300% of control in apoptotic cells, whereas KBres cells showed only a minor increase and no morphological response typical for apoptosis. The Ca(2+)-influx was mediated via calcium channels in the cell membrane. The HePC-induced influx is prevented by Gd3+, which blocks those calcium channels. Cells, grown in Ca(2+)-free medium, showed no apoptotic behaviour after treatment with HePC. If apoptosis was induced, an increased fatty acid and subsequent phospholipid biosynthesis was observed. This effect seems to be a specific marker of apoptosis in KB cells.

Influence of gelatin matrices cross-linked with transglutaminase on the properties of an enclosed bioactive material using beta-galactosidase as model system

Transglutaminase (protein-glutamine: amine gamma-glutamyltransferase, EC 2.3.2.13) from Streptoverticillium mobaraense has been used to stabilize immobilisates produced with beta-galactosidase (beta-D-galactoside galactohydrolase, EC 3.2.1.23) from Aspergillus oryzae and acid-processed gelatins of different qualities as support. The isopeptide level of N epsilon-(gamma-L-glutamyl)-L-lysine bonds formed by transglutaminase was determined to estimate their influence on the kinetic properties of the enclosed beta-galactosidase. An HPLC procedure using precolumn derivatization of the gelatin hydrolysates with FMOC-chloride was chosen which permits the analysis of cross-linked lysine with satisfactory precision. Depending on the gelatin quality, the degree of cross-links necessary for the transformation of gelatin into an insoluble protein was in the range 0.3-32.3% of the available lysine residues. beta-Galactosidase was entrapped in the gelatin matrices with a yield of 8-46% of the initial activity. Long reaction times for cross-linking were due to low yields rather than to the number of isopeptide bonds. Repeated use of the immobilisates did not lead to an appreciable loss of activity. The Vmax of beta-galactosidase were diminished by immobilization caused by a tighter package of the protein chains rather than by the extent of cross-links, while the obtained Km values of the free enzyme and the immobilisates were quite similar. Also, the pH and temperature of optima of the free enzyme and the gelatin immobilisates differ only slightly. The data suggest that the immobilization procedure only moderately affects the activity of enzymes catalysing the reaction of a small compound if gelatin with high jelly strength is cross-linked in a 10% solution with transglutaminase.

Combined extraction techniques of tumour cells and lipid/phospholipid assignment by two dimensional NMR spectroscopy

As the cell membranes are one of the targets of drug treatment in cancer cells, their membrane composition and variations in this composition need to be analyzed. Gradient selected 2D-NMR inverse heteronuclear chemical shift correlations are have described, which offer optimum sensitivity combined with a high reliability for unequivocal signal assignment in proton, carbon and phosphorous spectra, concerning neutral lipids and in particular phospholipids. Additionally, an extraction procedure is presented to extract subsequently the water soluble (PCA extract) and lipophilic metabolites (chloroform/methanol extract) from the same cell batch.

Early stage monitoring of miltefosine induced apoptosis in KB cells by multinuclear NMR spectroscopy

Synthetic ether lipids, like miltefosine (hexadecylphosphocholine), an alkylphosphocholine, are antineoplastic agents in vitro and in vivo. Their mode of action is mediated via the cell membrane, but the mechanism is still unclear. Miltefosine induces apoptosis in human epithelial KB cells, but slows down only proliferation in rat C6 glioma cells. NMR spectroscopy on lipid extracts reveals increased diacylglycerol and triacyglycerol biosynthesis in KB cells prior to DNA fragmentation indicating a CTP:phosphocholine-cytidylyl-transferase (CT) inhibition by the drug. Although C6 cells were morphologically affected by alterations in phospholipid composition and metabolism by a long term treatment (23 days) with the drug, no persistent diacylglycerol increase is observed.

Adaptation of cellular metabolism to anisosmotic conditions in a glial cell line, as assessed by 13C-NMR spectroscopy

13C-NMR spectroscopy of perchloric acid and lipid extracts of F98 glioma cells showed that volume-regulatory processes under anisosmotic conditions were accompanied by marked alterations in cellular metabolism. Production of alanine, glutamate, and glycine from [U-13C]-glucose is decreased under hypotonic stress and is oppositely increased under hypertonic stress. In contrast, degradation of these molecules is raised under hypotonic conditions and reduced under hypertonic conditions. Furthermore, phospholipid synthesis is decreased under hypertonic stress and increased under hypotonic stress. Obviously, glial metabolism is directed under hypertonic conditions to maintain a high level of small, osmotically active molecules, whereas under hypotonic conditions molecular fragments are increasingly incorporated into the phospholipids and so do not contribute to the osmotic pressure. The latter is evoked by the activation of membrane synthesis process to compensate for stretching and/or damaging of the membranes due to cell swelling.

Differences in intravenous and subcutaneous application of recombinant human erythropoietin: a multicenter trial

The aims of this clinical study were to compare the maintenance doses for intravenous (i.v.) and subcutaneous (SC) administration of recombinant human erythropoietin (rhEPO) and to investigate whether there is any difference in the increase of the packed cellular volume (PCV) per week under i.v. and SC administration of rhEPO from two production sites (Genetics Institute, Cambridge, USA; and Boehringer Mannheim, Penzberg, Germany). A total of 90 patients suffering from end-stage renal disease were included in the study. All patients had already been treated for at least 6 months with chronic hemodialysis. The study was carried out as a randomized, multicenter parallel group comparison study with a 1-week pretreatment phase, a subsequent 8-week double-blind phase, and a final open phase. The final open phase consisted of a correction phase and a maintenance phase. The production site had no influence on the PCV increase per week, and there were no differences with respect to tolerability. The median rhEPO dose required to maintain the target PCV of 30 to 35 vol.% was 33 U/kg body weight three times a week in the i.v. group compared with 22 U/kg in the SC group (i.e., an average of 30% less with SC administration). Development or aggravation of hypertension under rhEPO therapy was observed, especially during the correction phase and more frequently in the SC group than in the i.v. group. During the maintenance phase, there was no essential difference between the two groups.

A 13C NMR study on fluxes into the TCA cycle of neuronal and glial tumor cell lines and primary cells

Two tumor cell lines (C6 glioma and N1E-115 neuroblastoma), primary glia and primary neurons (from rat) were incubated with 2-13C-pyruvate and 3-13C-pyruvate in culture dishes. 13C NMR spectra of the cell extracts were used to determine the ratio of pyruvate carboxylase to pyruvate dehydrogenase activity. Pyruvate carboxylase activity was found higher in primary glia cells than in neurons. Glial cells synthesized more amino acids, ie, their TCA cycle was used to a larger extent for biosynthesis than is the case of neurons, where it is preferentially used for the energy metabolism.