Lutz Trahms

Publications of Lutz Trahms

• Magnetized Aerosols Comprising Superparamagnetic Iron Oxide Nanoparticles Improve Targeted Drug and Gene Delivery to the Lung.

  Authors: Guenther Hasenpusch, Johannes Geiger, Kai Wagner, Olga Mykhaylyk, Frank Wiekhorst, Lutz Trahms, Alexandra Heidsieck, Bernhard Gleich, Christian Bergemann, Manish K Aneja, Carsten Rudolph

  Pharmaceutical research. 01/2012;

  PURPOSE: Targeted delivery of aerosols could not only improve efficacy of inhaled drugs but also reduce side effects resulting from their accumulation in healthy tissue. Here we investigated thePURPOSE: Targeted delivery of aerosols could not only improve efficacy of inhaled drugs but also reduce side effects resulting from their accumulation in healthy tissue. Here we investigated the impact of magnetized aerosols on model drug accumulation and transgene expression in magnetically targeted lung regions of unanesthetized mice. METHODS: Solutions containing superparamagnetic iron oxide nanoparticles (SPIONs) and model drugs (fluorescein or complexed plasmid DNA) were nebulized to unanesthetized mice under the influence of an external magnetic gradient directed to the lungs. Drug accumulation and transgene expression was subsequently measured at different time points. RESULTS: We could demonstrate 2-3 fold higher accumulation of the model drug fluorescein and specific transgene expression in lung regions of mice which had been exposed to an external magnetic gradient during nebulization compared to the control mice without any exposure to magnetic gradient. CONCLUSIONS: Magnetized aerosols present themselves as an efficient approach for targeted pulmonary delivery of drugs and gene therapeutic agents in order to treat localized diseases of the deeper airways.

• Identification of Magnetic Nanoparticles for Combined Positioning and Lentiviral Transduction of Endothelial Cells.

  Authors: Daniela Wenzel, Sarah Rieck, Sarah Vosen, Olga Mykhaylyk, Christina Trueck, Dietmar Eberbeck, Lutz Trahms, Katrin Zimmermann, Alexander Pfeifer, Bernd K Fleischmann

  Pharmaceutical research. 01/2012;

  PURPOSE: The combination of magnetic nanoparticles (MNPs) with a magnetic field is a powerful approach to enable cell positioning and/or local gene therapy. Because physical requirements for MNPsPURPOSE: The combination of magnetic nanoparticles (MNPs) with a magnetic field is a powerful approach to enable cell positioning and/or local gene therapy. Because physical requirements for MNPs differ between these two applications we have explored whether the use of different MNPs can provide site-specific positioning combined with efficient viral transduction of endothelial cells (ECs). METHODS: A variety of MNPs was screened for magnetic cell labeling and lentivirus binding. Then two different MNPs were chosen and their combined application was evaluated regarding EC magnetization and transduction efficiency. RESULTS: The combined use of PEI-Mag2 and NDT-Mag1 particles provided both efficient lentiviral transduction and high magnetic responsiveness of ECs that could be even retained within the vascular wall under flow conditions. The use of these MNPs did not affect biological characteristics of ECs like surface marker expression and vascular network formation. Importantly, with this method we could achieve an efficient functional overexpression of endothelial nitric oxide synthase in ECs. CONCLUSIONS: The application of two different MNPs provides optimal results for magnetic labeling of ECs in combination with viral transduction. This novel approach could be very useful for targeted gene therapy ex vivo and site-specific cell replacement in the vascular system.

• Magnetorelaxometry Assisting Biomedical Applications of Magnetic Nanoparticles.

  Authors: Frank Wiekhorst, Uwe Steinhoff, Dietmar Eberbeck, Lutz Trahms

  Pharmaceutical research. 12/2011;

  Due to their biocompatibility and small size, iron oxide magnetic nanoparticles (MNP) can be guided to virtually every biological environment. MNP are susceptible to external magnetic fields and canDue to their biocompatibility and small size, iron oxide magnetic nanoparticles (MNP) can be guided to virtually every biological environment. MNP are susceptible to external magnetic fields and can thus be used for transport of drugs and genes, for heat generation in magnetic hyperthermia or for contrast enhancement in magnetic resonance imaging of biological tissue. At the same time, their magnetic properties allow one to develop sensitive and specific measurement methods to non-invasively detect MNP, to quantify MNP distribution in tissue and to determine their binding state. In this article, we review the application of magnetorelaxometry (MRX) for MNP detection. The underlying physical properties of MNP responsible for the generation of the MRX signal with its characteristic parameters of relaxation amplitude and relaxation time are described. Existing single and multi-channel MRX devices are reviewed. Finally, we thoroughly describe some applications of MRX to cellular MNP quantification, MNP organ distribution and MNP-based binding assays. Providing specific MNP signals, a detection limit down to a few nanogram MNP, in-vivo capability in conscious animals and measurement times of a few seconds, MRX is a valuable tool to improve the application of MNP for diagnostic and therapeutic purposes.

• Minimal-invasive magnetic heating of tumors does not alter intra-tumoral nanoparticle accumulation, allowing for repeated therapy sessions: an in vivo study in mice.

  Authors: Melanie Kettering, Heike Richter, Frank Wiekhorst, Sibylle Bremer-Streck, Lutz Trahms, Werner Alois Kaiser, Ingrid Hilger

  Nanotechnology. 11/2011; 22(50):505102.

  Localized magnetic heating treatments (hyperthermia, thermal ablation) using superparamagnetic iron oxide nanoparticles (MNPs) continue to be an active area of cancer research. For generating theLocalized magnetic heating treatments (hyperthermia, thermal ablation) using superparamagnetic iron oxide nanoparticles (MNPs) continue to be an active area of cancer research. For generating the appropriate heat to sufficiently target cell destruction, adequate MNP concentrations need to be accumulated into tumors. Furthermore, the knowledge of MNP bio-distribution after application and additionally after heating is significant, firstly because of the possibility of repeated heating treatments if MNPs remain at the target region and secondly to study potential adverse effects dealing with MNP dilution from the target region over time. In this context, little is known about the behavior of MNPs after intra-tumoral application and magnetic heating. Therefore, the present in vivo study on the bio-distribution of intra-tumorally injected MNPs in mice focused on MNP long term monitoring of pre and post therapy over seven days using multi-channel magnetorelaxometry (MRX). Subsequently, single-channel MRX was adopted to study the bio-distribution of MNPs in internal organs and tumors of sacrificed animals. We found no distinct change of total MNP amounts in vivo during long term monitoring. Most of the MNP amounts remained in the tumors; only a few MNPs were detected in liver and spleen and less than 1% of totally injected MNPs were excreted. Apparently, the application of magnetic heating and the induction of apoptosis did not affect MNP accumulation. Our results indicate that MNP mainly remained within the injection side after magnetic heating over a seven-days-observation and therefore not affecting healthy tissue. As a consequence, localized magnetic heating therapy of tumors might be applied periodically for a better therapeutic outcome.

• Are brain currents detectable by means of low-field NMR? A phantom study.

  Authors: Nora Höfner, Hans-Helge Albrecht, Antonino Mario Cassará, Gabriel Curio, Stefan Hartwig, Jens Haueisen, Ingo Hilschenz, Rainer Körber, Sven Martens, Hans-Jürgen Scheer, Jens Voigt, Lutz Trahms, Martin Burghoff

  Magnetic resonance imaging. 09/2011; 29(10):1365-73.

  A number of different methods have been developed in order to detect the spreading of neuronal currents by means of noninvasive imaging techniques. However, all of these are subjected to limitationsA number of different methods have been developed in order to detect the spreading of neuronal currents by means of noninvasive imaging techniques. However, all of these are subjected to limitations in the temporal or spatial resolution. A new approach of neuronal current detection is based on the use of low-field nuclear magnetic resonance (LF-NMR) that records brain activity directly. In the following, we describe a phantom study in order to assess the feasibility of neuronal current detection using LF-NMR. In addition to that, necessary preliminary subject studies examining somatosensory evoked neuronal currents are presented. During the phantom study, the influences of two different neuronal time signals on (1)H-NMR signals were observed. The measurements were carried out by using a head phantom with an integrated current dipole to simulate neuronal activity. Two LF-NMR methods based on a DC and an AC (resonant) mechanism were utilized to study the feasibility of detecting both types of magnetic brain signals. Measurements were made inside an extremely magnetically shielded room by using a superconducting quantum interference device magnetometer system. The measurement principles were validated applying currents of higher intensity than those typical of the neuronal currents. Through stepwise reduction of the amplitude of the current dipole strength, the resolution limits of the two measuring procedures were found. The results indicate that it is necessary to improve the signal-to-noise ratio of the measurement system by at least a factor of 38 in order to detect typical human neuronal activity directly by means of LF-NMR. In addition to that, ways of achieving this factor are discussed.

• Nuclear magnetic relaxation in water revisited.

  Authors: Stefan Hartwig, Jens Voigt, Hans-Jürgen Scheer, Hans-Helge Albrecht, Martin Burghoff, Lutz Trahms

  The Journal of chemical physics. 08/2011; 135(5):054201.

  In this study, we revisited nuclear magnetic relaxation of (1)H in water at very low Larmor frequencies that has been studied intensively in earlier years. We make use of the recently developedIn this study, we revisited nuclear magnetic relaxation of (1)H in water at very low Larmor frequencies that has been studied intensively in earlier years. We make use of the recently developed superconducting quantum interference device based ultra-low field NMR technique, which enables much easier access to the longitudinal spin-lattice relaxation time T(1) and the transversal spin-spin relaxation time T(2) below several kHz than traditional field cycling methods. Our data reproduce and complement the earlier results, in that they corroborate the finding of an exchange process with a correlation time of about 0.34 ms at room temperature which can be attributed to the migration of hydronium and hydroxyl ions in neutral water via hydrogen bridges. The corresponding relaxation process is driven by the interaction of the protons with (17)O and contributes to the T(1) and the T(2) relaxation rate by about 0.12 s(-1). In addition, we found evidence of a very slow exchange process at about 100 Hz that has hitherto not been reported.

• The eccentricity effect of inhibition of return is resistant to practice.

  Authors: Yan Bao, Tilmann Sander, Lutz Trahms, Ernst Pöppel, Quan Lei, Bin Zhou

  Neuroscience letters. 06/2011; 500(1):47-51.

  Inhibition of return (IOR) refers to a delayed responding to targets appeared at previously cued location relative to an uncued novel location. In a recent study, Bao and Pöppel reported a functionalInhibition of return (IOR) refers to a delayed responding to targets appeared at previously cued location relative to an uncued novel location. In a recent study, Bao and Pöppel reported a functional dissociation of inhibitory processing in the visual field with much stronger IOR magnitude in the far periphery relative to the perifoveal visual field up to 15° eccentricity. The present study aimed to examine whether this effect is sensitive to participant experience or practice. Consistent with previous findings, our data demonstrated a larger IOR magnitude at 21° relative to 7° stimulus eccentricity. More importantly, no practice-related IOR magnitude changes were observed for both perifoveal and peripheral stimuli, although response times did decrease significantly with practice. These results suggest that the eccentricity effect of IOR is a robust phenomenon which is resistant to practice.

• Simultaneous measurements of somatosensory evoked AC and near-DC MEG signals.

  Authors: Rainer Körber, Gabriel Curio, Stefan Hartwig, Ingo Hilschenz, Nora Höfner, Hans-Jürgen Scheer, Lutz Trahms, Jens Voigt, Martin Burghoff

  Biomedizinische Technik. Biomedical engineering. 03/2011; 56(2):91-7.

  Magnetoencephalography measurements of somatosensory evoked brain activity taken inside an extremely magnetically shielded room are reported. The massive low frequency shielding in combination with aMagnetoencephalography measurements of somatosensory evoked brain activity taken inside an extremely magnetically shielded room are reported. The massive low frequency shielding in combination with a high sampling rate enabled the simultaneous observation of AC and near-DC effects. Neuronal activation was achieved by repetitive electrostimulation of the right median nerve above motor threshold using repetition rates from 3 Hz to 12 Hz. Stimulation sequences lasted for 10 s and were interspersed with periods of rest of equal length. The recorded magnetic fields, inferred for the N20m and a sustained near-DC component, revealed mainly dipolar patterns with mutually rotated orientations with angles of rotation of 30° and 75°. At the start of the stimulation we observed a fast rise within 100 ms in the evoked magnetic near-DC fields for which a maximum equivalent current dipole strength of 65 nAm was obtained. The sustained fields decayed by a factor of ∼4 to a lower DC-level B(γ) with a time constant τ of order of seconds. For 12 Hz repetition rate B(γ) was decreased. We suggest that the sustained neuronal activity evoked by repetitive electrostimulation could provide a suitable scheme to realize the direct detection of DC effects of neuronal currents via low field magnetic resonance.

• Non-invasive simultaneous recording of neuronal and vascular signals in subacute ischemic stroke.

  Authors: Stefanie Leistner, Tilmann Sander-Thoemmes, Heidrun Wabnitz, Michael Moeller, Michaela Wachs, Gabriel Curio, Rainer Macdonald, Lutz Trahms, Bruno-Marcel Mackert

  Biomedizinische Technik. Biomedical engineering. 02/2011; 56(2):85-90.

  In acute focal cerebral ischemia blood flow and neuronal activity change dramatically. A better understanding of the pathophysiological interactions of these two important parameters is limited owingIn acute focal cerebral ischemia blood flow and neuronal activity change dramatically. A better understanding of the pathophysiological interactions of these two important parameters is limited owing to the lack of noninvasive techniques to simultaneously measure these parameters in humans. In this feasibility study, we used DC-magnetoencephalography and near-infrared spectroscopy to find out whether blood flow and neuronal activity as well as neurovascular coupling can be analyzed in patients suffering from subacute ischemic stroke. In a simple motor test condition, six patients with subacute ischemic stroke performed self-paced finger movements (30-s periods of movement, separated by 30-s periods of rest; for a total of 15 min). Combined DC-magnetoencephalography and near-infrared spectroscopy were recorded over the affected and unaffected hemispheres. As a control group, four healthy subjects were investigated. In four out of six patients, the time courses of both signals closely followed the motor task cycles revealing significant differences between movement and rest periods. The vascular signal reached a maximum 1-5 s later than the neuronal signals. This proof-of-principle study demonstrates that it has become feasible to simultaneously and noninvasively monitor neuronal and vascular signal changes in patients in the subacute state of ischemic stroke.

• Processing of visual stimuli in borderline personality disorder: a combined behavioural and magnetoencephalographic study.

  Authors: Angela Merkl, Nina Ammelburg, Sabine Aust, Stefan Roepke, Hans Reinecker, Lutz Trahms, Isabella Heuser, Tilmann Sander

  International journal of psychophysiology : official journal of the International Organization of Psychophysiology. 12/2010; 78(3):257-64.

  Behavioral studies on facial emotion recognition yielded heterogeneous results in patients with Borderline Personality Disorder (BPD). Extrastriate cortex hyperactivation has been demonstrated inBehavioral studies on facial emotion recognition yielded heterogeneous results in patients with Borderline Personality Disorder (BPD). Extrastriate cortex hyperactivation has been demonstrated in imaging studies in patients with BPD during face recognition, but electrophysiological studies are lacking. The aim was to investigate temporal processes following face perception in patients with BPD. Magnetoencephalography (MEG) was used in eleven non-medicated patients with BPD and nine age-matched healthy subjects. Behavioral responses to visual stimuli and an emotion discrimination task were evaluated. First, participants had to silently watch faces, houses and animals. Emotional expressive faces then had to be judged from two basic emotions in a two-alternative forced choice task. Regional field power (RFP) of MEG signals was obtained from two regions of interest: Temporal and occipital areas. Psychometric assessment was performed. Patients with BPD had significantly reduced RFP amplitudes in the right posterior occipital region of interest, for the time window between 150 and 160 ms, irrespective of the type of visual stimulus or the emotional face category. Patients with BPD had significantly higher error rates for recognition of emotional expressive faces compared to healthy controls though they showed a higher accuracy in detecting fearful faces. Controls improved during face recognition, whereas patients showed no learning effect. This MEG study provides evidence for disturbances in cortical visual perception in BPD patients regardless of emotional salience of the stimulus. In line with previous studies subtle deficits in visual perception might be related to impairment in interpersonal communication in BPD.

• Dissociation of summation and peak latencies in visual processing: an MEG study on stimulus eccentricity.

  Authors: Bin Zhou, Yan Bao, Tilmann Sander, Lutz Trahms, Ernst Pöppel

  Neuroscience letters. 10/2010; 483(2):101-4.

  Research on the temporal characteristics of visual processing, as measured with critical flicker fusion or the latency of visual evoked potential (VEP), shows controversial results if differentResearch on the temporal characteristics of visual processing, as measured with critical flicker fusion or the latency of visual evoked potential (VEP), shows controversial results if different eccentricities of visual stimuli are compared. To clarify this question, a direct measure of cortical activity with magnetoencephalography (MEG) was applied to examine the neuronal summation latency and peak latency for both near and far peripheral stimuli. Consistent with cortical magnification, the peak amplitude for less eccentric stimuli was larger than that for more eccentric stimuli. More importantly, the current data also demonstrated longer cortical summation latency and peak latency for more eccentric visual stimuli, but only the summation latency difference between near and far stimuli correlated with the peak amplitude difference between near and far stimuli. These results suggest dissociable mechanisms of summation latency and peak latency with respect to their contributions to the stimulus eccentricity effect, and provide potential explanations for controversial results in previous studies.

• NMR at very low fields.

  Authors: Lutz Trahms, Martin Burghoff

  Magnetic resonance imaging. 10/2010; 28(8):1244-50.

  Although nuclear magnetic resonance in low fields around or below the Earth's magnetic field is almost as old as nuclear magnetic resonance itself, the recent years have experienced a revival of thisAlthough nuclear magnetic resonance in low fields around or below the Earth's magnetic field is almost as old as nuclear magnetic resonance itself, the recent years have experienced a revival of this technique that is opposed to the common trend towards higher and higher fields. The background of this development is the expectation that the low-field domain may open a new window for the study of molecular structure and dynamics. Here, we will give an overview on the specific features in the low-field domain, both from the technical and from the physical point of view. In addition, we present a short passage on the option of magnetic resonance imaging in fields of the micro-Tesla range.

• Magnetoencephalography discriminates modality-specific infraslow signals less than 0.1 Hz.

  Authors: Stefanie Leistner, Tilmann H Sander, Gerd Wuebbeler, Alfred Link, Clemens Elster, Gabriel Curio, Lutz Trahms, Bruno-Marcel Mackert

  Neuroreport. 02/2010; 21(3):196-200.

  DC-magnetoencephalography (DC-MEG) technique has been refined and allows to record cortical activity in the infraslow frequency range less than 0.1 Hz noninvasively. Important questions however,DC-magnetoencephalography (DC-MEG) technique has been refined and allows to record cortical activity in the infraslow frequency range less than 0.1 Hz noninvasively. Important questions however, remained, especially, how specific these infraslow activations can be recorded and whether different activations, for example, motor versus acoustic, can be separated. To clarify these questions, in the present DC-MEG study, cortical infraslow activity was investigated intraindividually in response to different activation modalities, that is, motor versus acoustic: in 13 individuals, 30-s periods of finger movement or listening to concert music, were interleaved for 60 min. DC-MEG was capable to resolve intermodal differences concerning the relative amplitudes, field patterns, and source localizations. These results clarify that DC-MEG allows to identify and to discriminate modality-specific infraslow cortical neuronal signals.

• Cross-Correlation of Motor Activity Signals from dc-Magnetoencephalography, Near-Infrared Spectroscopy, and Electromyography.

  Authors: Tilmann Heinrich Sander, Stefanie Leistner, Heidrun Wabnitz, Bruno-Marcel Mackert, Rainer Macdonald, Lutz Trahms

  Comp. Int. and Neurosc. 01/2010; 2010.

• Imaging of magnetic nanoparticles based on magnetorelaxometry with sequential activation of inhomogeneous magnetization fields

  Authors: Uwe Steinhoff, Frank Wiekhorst, Daniel Baumgarten, Jens Haueisen, Lutz Trahms

  Biomedizinische Technik. 01/2010; Suppl. 1.

  In magnetorelaxometry (MRX), the specific magnetization decay of superparamagnetic nanoparticles after switching off a large magnetization field is detected using superconducting quantum interferenceIn magnetorelaxometry (MRX), the specific magnetization decay of superparamagnetic nanoparticles after switching off a large magnetization field is detected using superconducting quantum interference devices (SQUIDs). We present a concept how quantitative 3D images of the magnetic nanoparticle distribution in biological tissue can be obtained by combining MRX measurements using multichannel SQUID systems with sequential activation of spatially inhomogeneous magnetization fields. The inverse problem of the image reconstruction is stabilized by the combination of spatially inhomogeneous magnetization fields. As an example, we demonstrate the numeric reconstruction of a Shepp-Logan phantom with 4096 voxels in a 10x10x10cm3 volume under the assumption of a signal to noise ratio of 250.

• Cross-correlation of motor activity signals from dc-magnetoencephalography, near-infrared spectroscopy, and electromyography.

  Authors: Tilmann H Sander, Stefanie Leistner, Heidrun Wabnitz, Bruno-Marcel Mackert, Rainer Macdonald, Lutz Trahms

  Computational intelligence and neuroscience. 01/2010;

  Neuronal and vascular responses due to finger movements were synchronously measured using dc-magnetoencephalography (dcMEG) and time-resolved near-infrared spectroscopy (trNIRS). The finger movementsNeuronal and vascular responses due to finger movements were synchronously measured using dc-magnetoencephalography (dcMEG) and time-resolved near-infrared spectroscopy (trNIRS). The finger movements were monitored with electromyography (EMG). Cortical responses related to the finger movement sequence were extracted by independent component analysis from both the dcMEG and the trNIRS data. The temporal relations between EMG rate, dcMEG, and trNIRS responses were assessed pairwise using the cross-correlation function (CCF), which does not require epoch averaging. A positive lag on a scale of seconds was found for the maximum of the CCF between dcMEG and trNIRS. A zero lag is observed for the CCF between dcMEG and EMG. Additionally this CCF exhibits oscillations at the frequency of individual finger movements. These findings show that the dcMEG with a bandwidth up to 8 Hz records both slow and faster neuronal responses, whereas the vascular response is confirmed to change on a scale of seconds.

• Recent advances in modeling and analysis of bioelectric and biomagnetic sources.

  Authors: Tilmann H Sander, Thomas R Knösche, Alois Schlögl, Florian Kohl, Carsten H Wolters, Jens Haueisen, Lutz Trahms

  Biomedizinische Technik. Biomedical engineering. 01/2010; 55(2):65-76.

  Determining the centers of electrical activity in the human body and the connectivity between different centers of activity in the brain is an active area of research. To understand brain functionDetermining the centers of electrical activity in the human body and the connectivity between different centers of activity in the brain is an active area of research. To understand brain function and the nature of cardiovascular diseases requires sophisticated methods applicable to non-invasively measured bioelectric and biomagnetic data. As it is difficult to solve for all unknown parameters at once, several strains of data analysis have been developed, each trying to solve a different part of the problem and each requiring a different set of assumptions. Current trends and results from major topics of electro- and magnetoencephalographic data analysis are presented here together with the aim of stimulating research into the unification of the different approaches. The following topics are discussed: source reconstruction using detailed finite element modeling to locate sources deep in the brain; connectivity analysis for the quantification of strength and direction of information flow between activity centers, preferably incorporating an inverse solution; the conflict between the statistical independence assumption of sources and a possible connectivity; the verification and validation of results derived from non-invasively measured data through animal studies and phantom measurements. This list already indicates the benefits of a unified view.

• Polarization encoding as a novel approach to MRI.

  Authors: Jaakko O Nieminen, Martin Burghoff, Lutz Trahms, Risto J Ilmoniemi

  Journal of magnetic resonance (San Diego, Calif. : 1997). 11/2009;

  In magnetic resonance imaging (MRI), there have been three basic techniques to encode the spatial origin of the signals, i.e. Fourier and radio frequency encoding and the use of sensitivityIn magnetic resonance imaging (MRI), there have been three basic techniques to encode the spatial origin of the signals, i.e. Fourier and radio frequency encoding and the use of sensitivity information of sensor arrays. In this paper, we introduce a new encoding method, which we call polarization encoding. The method utilizes sets of polarizing fields with various spatial profiles; it is tailored for MRI at ultra-low fields (ULF MRI). In ULF MRI, signals from a prepolarized sample are typically detected using an array of SQUID (superconducting quantum interference device) sensors at microtesla fields. The prepolarization is achieved with a field of the order of 10-100mT preceding the signal acquisition. In polarization encoding, the prepolarizing field is varied in a way to gain additional information about the sample. The method may also prove useful for modalities that in the absence of any precession aim to image the DC magnetization profile of a sample.

• Quantification of drug-loaded magnetic nanoparticles in rabbit liver and tumor after in vivo administration

  Authors: Rainer Tietze, Roland Jurgons, Stefan Lyer, Eveline Schreiber, Frank Wiekhorst, Dietmar Eberbeck, Heike Richter, Uwe Steinhoff, Lutz Trahms, Christoph Alexiou

  Journal of Magnetism and Magnetic Materials. 05/2009; 321(10):1465-1468.

  Magnetic nanoparticles have been investigated for biomedical applications for more than 30 years. The development of biocompatible nanosized drug delivery systems for specific targeting ofMagnetic nanoparticles have been investigated for biomedical applications for more than 30 years. The development of biocompatible nanosized drug delivery systems for specific targeting of therapeutics is imminent in medical research, especially for treating cancer and vascular diseases. We used drug-labeled magnetic iron oxide nanoparticles, which were attracted to an experimental tumor in rabbits with an external magnetic field (magnetic drug targeting, MDT). Aim of this study was to detect and quantify the biodistribution of the magnetic nanoparticles by magnetorelaxometry. The study shows higher amount of nanoparticles in the tumor after intraarterial application and MDT compared to intravenous administration.

• Neuronal current detection with low-field magnetic resonance: simulations and methods.

  Authors: Antonino Mario Cassará, Bruno Maraviglia, Stefan Hartwig, Lutz Trahms, Martin Burghoff

  Magnetic resonance imaging. 03/2009;

  The noninvasive detection of neuronal currents in active brain networks [or direct neuronal imaging (DNI)] by means of nuclear magnetic resonance (NMR) remains a scientific challenge. Many differentThe noninvasive detection of neuronal currents in active brain networks [or direct neuronal imaging (DNI)] by means of nuclear magnetic resonance (NMR) remains a scientific challenge. Many different attempts using NMR scanners with magnetic fields >1 T (high-field NMR) have been made in the past years to detect phase shifts or magnitude changes in the NMR signals. However, the many physiological (i.e., the contemporarily BOLD effect, the weakness of the neuronal-induced magnetic field, etc.) and technical limitations (e.g., the spatial resolution) in observing the weak signals have led to some contradicting results. In contrast, only a few attempts have been made using low-field NMR techniques. As such, this paper was aimed at reviewing two recent developments in this front. The detection schemes discussed in this manuscript, the resonant mechanism (RM) and the DC method, are specific to NMR instrumentations with main fields below the earth magnetic field (50 muT), while some even below a few microteslas (ULF-NMR). However, the experimental validation for both techniques, with differentiating sensitivity to the various neuronal activities at specific temporal and spatial resolutions, is still in progress and requires carefully designed magnetic field sensor technology. Additional care should be taken to ensure a stringent magnetic shield from the ambient magnetic field fluctuations. In this review, we discuss the characteristics and prospect of these two methods in detecting neuronal currents, along with the technical requirements on the instrumentation.