27 results on '"Palomäki, T."'
Search Results
2. Multi-walled carbon nanotubes (MWCNTs) grown directly on tetrahedral amorphous carbon (ta-C): An interfacial study
- Author
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Laurila, T., Sainio, S., Jiang, H., Palomäki, T., Pitkänen, O., Kordas, K., and Koskinen, J.
- Published
- 2015
- Full Text
- View/download PDF
3. What determines the electrochemical properties of nitrogenated amorphous carbon thin films?
- Author
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Etula, J. (Jarkko), Wester, N. (Niklas), Liljeström, T. (Touko), Sainio, S. (Sami), Palomäki, T. (Tommi), Arstila, K. (Kai), Sajavaara, T. (Timo), Koskinen, J. (Jari), and Caro, M. A. (Miguel A.)
- Subjects
Nitrogen ,Thin films ,Probes ,Deposition ,Electrodes - Abstract
Linking structural and compositional features with the observed electrochemical performance is often ambiguous and sensitive to known and unknown impurities. Here an extensive experimental investigation augmented by computational analyses is linked to the electrochemical characterization of in situ nitrogen-doped tetrahedral amorphous carbon thin films (ta-C:N). Raman spectroscopy combined with X-ray reflectivity shows nitrogen disrupting the sp3 C–C structure of the reference ta-C, supported by the observations of graphitic nitrogen substitution in X-ray absorption spectroscopy. The surface roughness also increases, as observed in atomic force microscopy and atomic-level computational analyses. These changes are linked to significant increases in the hydrogen and oxygen content of the films by utilizing time-of-flight elastic recoil detection analysis. The conductivity of the films increases as a function of the nitrogen content, which is seen as a facile reversible outer-sphere redox reaction on ta-C:N electrodes. However, for the surface-sensitive inner-sphere redox (ISR) analytes, it is shown that the electrochemical response instead follows the oxygen and hydrogen content. We argue that the passivation of the required surface adsorption sites by hydrogen decreases the rates of all of the chemically different ISR probes investigated on nitrogenated surfaces significantly below that of the nitrogen-free reference sample. This hypothesis can be used to readily rationalize many of the contradictory electrochemical results reported in the literature.
- Published
- 2021
4. Trends in carbon, oxygen, and nitrogen core in the x-ray absorption spectroscopy of carbon nanomaterials:a guide for the perplexed
- Author
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Sainio, S. (Sami), Wester, N. (Niklas), Aarva, A. (Anja), Titus, C. J. (Charles J.), Nordlund, D. (Dennis), Kauppinen, E. I. (Esko I.), Leppänen, E. (Elli), Palomäki, T. (Tommi), Koehne, J. E. (Jessica E.), Pitkänen, O. (Olli), Kordas, K. (Krisztian), Kim, M. (Maria), Lipsanen, H. (Harri), Mozetič, M. (Miran), Caro, M. A. (Miguel A.), Meyyappan, M. (M.), Koskinen, J. (Jari), Laurila, T. (Tomi), Sainio, S. (Sami), Wester, N. (Niklas), Aarva, A. (Anja), Titus, C. J. (Charles J.), Nordlund, D. (Dennis), Kauppinen, E. I. (Esko I.), Leppänen, E. (Elli), Palomäki, T. (Tommi), Koehne, J. E. (Jessica E.), Pitkänen, O. (Olli), Kordas, K. (Krisztian), Kim, M. (Maria), Lipsanen, H. (Harri), Mozetič, M. (Miran), Caro, M. A. (Miguel A.), Meyyappan, M. (M.), Koskinen, J. (Jari), and Laurila, T. (Tomi)
- Abstract
Successful deployment of carbon nanomaterials in many applications, such as sensing, energy storage, and catalysis, relies on the selection, synthesis, and tailoring of the surface properties. Predictive analysis of the behavior is difficult without detailed knowledge of the differences between various carbon nanomaterials and their surface functionalization, thus leaving the selection process to traditional trial-and-error work. The present characterization fills this knowledge gap for carbon nanomaterial surface properties with respect to chemical states and functionalization. We present an overview of the chemical trends that can be extracted from soft X-ray absorption spectroscopy (XAS) spectra on an extended set of nonideal carbon nanomaterials as a function of sp2 bonded carbon and bond ordering. In particular, the surface chemical state, the presence of long-range order in the carbon matrix, and a qualitative estimation of the amount of oxygen and nitrogen and their respective functional group formation on the material surface, together with the detailed material fabrication parameters, are reported. The results expand our understanding of carbon nanomaterial functionalization, which can support material selection in practice, provided that the specifications of the application are known.
- Published
- 2021
5. Members of the amylovora group of Erwinia are cellulolytic and possess genes homologous to the type II secretion pathway
- Author
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Riekki, R., Palomäki, T., Virtaharju, O., Kokko, H., Romantschuk, M., and Saarilahti, H. T.
- Published
- 2000
- Full Text
- View/download PDF
6. Unmodified and multi-walled carbon nanotube modified tetrahedral amorphous carbon (ta-C) films as in vivo sensor materials for sensitive and selective detection of dopamine
- Author
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Palomäki, T. (Tommi), Peltola, E. (Emilia), Sainio, S. (Sami), Wester, N. (Niklas), Pitkänen, O. (Olli), Kordas, K. (Krisztian), Koskinen, J. (Jari), Laurila, T. (Tomi), Palomäki, T. (Tommi), Peltola, E. (Emilia), Sainio, S. (Sami), Wester, N. (Niklas), Pitkänen, O. (Olli), Kordas, K. (Krisztian), Koskinen, J. (Jari), and Laurila, T. (Tomi)
- Abstract
Unmodified and multi-walled carbon nanotube (MWCNT) modified tetrahedral amorphous carbon (ta-C) films of 15 and 50 nm were investigated as potential in vivo sensor materials for the detection of dopamine (DA) in the presence of the main interferents, ascorbic acid (AA) and uric acid (UA). The MWCNTs were grown directly on ta-C by chemical vapor deposition (designated as ta-C+CNT) and were characterized with X-ray photoelectron spectroscopy, Raman spectroscopy, scanning and transmission electron microscopy. Electroanalytical sensitivity and selectivity were determined with cyclic voltammetry. Biocompatibility of the materials was assessed with cell cultures of mouse neural stem cells (mNSCs). The detection limits of DA for both ta-C and ta-C+CNT electrodes ranged from 40 to 85 nM, which are well within the required range for in vivo detection. The detection limits were lower for both ta-C and ta-C+CNT electrodes with 50 nm of ta-C compared to 15 nm. The ta-C electrodes showed a large dynamic linear range of 0.01–100 µM but could not resolve between the oxidation peaks of DA, AA and UA. Modification with MWCNTs, however, resulted in excellent selectivity and all three analytes could be detected simultaneously at physiologically relevant concentrations using cyclic voltammetry. Based on cell culture of mNSCs, both ta-C and ta-C+CNT exhibited good biocompatibility, demonstrating their potential as in vivo sensor materials for the detection of DA.
- Published
- 2018
7. Corrigendum to “Carbon nanotube (CNT) forest on diamond-like carbon (DLC) electrode improves electrochemical sensitivity towards dopamine by two orders of magnitude” [Sens. Actuators B 211 (2015) 177–186]
- Author
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Sainio, S., primary, Palomäki, T., additional, Rhode, S., additional, Kauppila, M., additional, Pitkänen, O., additional, Selkälä, T., additional, Toth, G., additional, Kordas, K., additional, Moram, M., additional, Koskinen, J., additional, and Laurila, T., additional
- Published
- 2016
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8. Ultrathin undoped tetrahedral amorphous carbon films: thickness dependence of the electronic structure and implications for their electrochemical behaviour
- Author
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Protopopova, V. S., primary, Wester, N., additional, Caro, M. A., additional, Gabdullin, P. G., additional, Palomäki, T., additional, Laurila, T., additional, and Koskinen, J., additional
- Published
- 2015
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9. Isolation and characterization of new C-terminal substitution mutations affecting secretion of polygalacturonase in Erwinia carotovora ssp. carotovora
- Author
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Palomäki, T, primary and Saarilahti, H.T, additional
- Published
- 1997
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10. The extreme C-terminus is required for secretion of both the native polygalacturonase (PehA) and PehA-Bla hybrid proteins in Erwinia carotovora subsp. carotovora
- Author
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Palomäki, T., primary and T. Saarilahti, H., additional
- Published
- 1995
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11. 'Maternity clinic on the Net service' and its introduction into practice: experiences of maternity-care professionals.
- Author
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Kouri P, Turunen H, and Palomäki T
- Abstract
OBJECTIVE: to describe the experiences of maternity-care professionals using an Internet-based network service, called Net Clinic, and the opportunities and obstacles they encountered in Net Clinic while organising their work and developing their know-how. DESIGN: qualitative information gathered from semi-structured thematic interviews. SETTING: four maternity care units in Eastern Finland (one antenatal ward in a university hospital, one antenatal ward in a central hospital, two maternity clinics in the community). PARTICIPANTS: five midwives, two public health nurses and three doctors. FINDINGS: all participants considered adequate privacy protection a prerequisite for development. They anticipated that because of their computer skills, young people would be able to use information and communication technology (ICT) as part of maternity-care services naturally. Managerial support, such as allocation of time and equipment, was extremely important during the introductory phase. The participants were divided into three groups based on their experiences of implementing Net Clinic: (1) 'doubters' did not believe in their own ICT competence and were afraid of using Net Clinic. They also showed resistance to Net Clinic. Doubters wanted versatile and personal guidance in ICT skills; (2) 'accepters' agreed that progress in ICT would inevitably affect their work. Development was considered difficult without awareness of the benefits of ICT, and Net Clinic was expected to increase their workload. Accepters preferred to have one-to-one ICT training; (3) 'future confidents' saw ICT as a useful tool for developing maternity care. They recognised the opportunities implicit in network collaboration and wanted versatile user training in ICT. They wanted successful network service models and were eager to develop them. IMPLICATIONS FOR THE FUTURE: families will increase their knowledge levels, as those who will be future parents are learning to use public network services at school. The increasing diversity of family structure will be a challenge to maternity care. Changes in maternity services can be accomplished with new e-Working models developed through diversified co-operation and with managerial support. The crucial question will be the attitude of maternity-care professionals towards Internet-based network service in their work. [ABSTRACT FROM AUTHOR]
- Published
- 2005
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12. Isolation and characterization of new C‐terminal substitution mutations affecting secretion of polygalacturonase in Erwinia carotovorassp. carotovora
- Author
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Palomäki, T and Saarilahti, H.T
- Abstract
An intact C‐terminus was previously shown to be required for stability and secretion of the polygalacturonase (PehA) in Erwinia carotovorassp. carotovora. Here we have analyzed the effects of amino acid (aa) substitutions generated to five C‐terminal positions of PehA. Conservation of two hydrophobic and one non‐hydrophobic residue (V372, V374 and N371, respectively) was found to be essential for maintenance of the protein stability. As an exception, one of the mutants (V372G) did not show major effects on protein stability, as determined by immunoblots and enzyme activity assay, yet it prevented the secretion completely. We conclude that the C‐terminus of PehA is directly involved in the formation or stabilization of a conformation‐sensitive structure needed for recognition of the protein as secreted.
- Published
- 1997
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13. Haptic Feedback Compared with Visual Feedback for BCI
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Kauhanen, L., Palomäki, T., Jylänki, P., Aloise, F., Nuttin, Marnix, and Millán, José del R.
- Subjects
InformationSystems_MODELSANDPRINCIPLES ,InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI) - Abstract
Feedback plays an important role when learning to use a Brain-Computer Interface (BCI). Here we compare visual and haptic feedback in a short experiment. By imagining left and right hand movements, six subjects tried to control a BCI with the help of either visual or haptic feedback every 1s. Alpha band EEG signals from C3 and C4 were classified. The classifier was updated after each prediction using correct class information. Thus feedback could be given throughout the experiment. Subjects got better at controlling the BCI during the experiment independent of the feedback modality. Haptic feedback did not present any artifacts to the signals. More research is required on haptic feedback for BCI-applications because it frees visual attention to other tasks.
14. Vibrotactile Feedback in the Context of Mu-Rhythm based BCI
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Cincotti, F., Kauhanen, L., Aloise, F., Palomäki, T., Caporusso, N., Jylänki, P., Mattia, D., Babiloni, F., Vanacker, G., Nuttin, Marnix, Marciani, M. G., and Millán, José del R.
- Subjects
InformationSystems_INFORMATIONINTERFACESANDPRESENTATION(e.g.,HCI) - Abstract
Brain-Computer Interfaces (BCIs) need an uninterrupted flow of feedback to the user, which is usually delivered through the visual channel. Our aim is to explore the benefits of vibrotactile feedback during users� training and control of EEG-based BCI applications. An experimental setup for delivery of vibrotactile feedback, including specific hardware and software arrangements, was specified. We compared vibrotactile and visual feedback, addressing the performance in presence of a complex visual task on the same (visual) or different (tactile) sensory channel. The preliminary experimental setup included a simulated BCI control. in which all parts reflected the computational and actuation process of an actual BCI, except the souce, which was simulated using a �noisy� PC mouse. Results indicated that the vibrotactile channel can function as a valuable feedback modality with reliability comparable to the classical visual feedback. Advantages of using a vibrotactile feedback emerged when the visual channel was highly loaded by a complex task.
15. Influence of enzyme immobilization and skin-sensor interface on non-invasive glucose determination from interstitial fluid obtained by magnetohydrodynamic extraction.
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Kemp E, Palomäki T, Ruuth IA, Boeva ZA, Nurminen TA, Vänskä RT, Zschaechner LK, Pérez AG, Hakala TA, Wardale M, Haeggström E, and Bobacka J
- Subjects
- Blood Glucose, Blood Glucose Self-Monitoring, Enzymes, Immobilized, Extracellular Fluid, Glucose, Biosensing Techniques, Glucose Oxidase
- Abstract
We integrated a magnetohydrodynamic fluid extractor with an amperometric glucose biosensor to develop a wearable device for non-invasive glucose monitoring. Reproducible fluid extraction through the skin and efficient transport of the extracted fluid to the biosensor surface are prerequisites for non-invasive glucose monitoring. We optimized the enzyme immobilization and the interface layer between the sensing device and the skin. The monitoring device was evaluated by extracting fluid through porcine skin followed by glucose detection at the biosensor. The biosensor featured a screen-printed layer of Prussian Blue that was coated with a layer containing glucose oxidase. Both physical entrapment of glucose oxidase in chitosan and tethering of glucose oxidase to electrospun nanofibers were evaluated. Binding of glucose oxidase to nanofibers under mild conditions provided a stable biosensor with analytical performance suitable for accurate detection of micromolar concentrations of glucose. Hydrogels of varying thickness (95-2000 μm) as well as a thin (30 μm) nanofibrous polycaprolactone mat were studied as an interface layer between the biosensor and the skin. The effect of mass transfer phenomena at the biosensor-skin interface on the analytical performance of the biosensor was evaluated. The sensing device detected glucose extracted through porcine skin with an apparent (overall) sensitivity of -0.8 mA/(M·cm
2 ), compared to a sensitivity of -17 mA/(M·cm2 ) for measurement in solution. The amperometric response of the biosensor correlated with the glucose concentration in the fluid that had been extracted through porcine skin with the magnetohydrodynamic technique., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2022
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16. Integrating Carbon Nanomaterials with Metals for Bio-sensing Applications.
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Sainio S, Leppänen E, Mynttinen E, Palomäki T, Wester N, Etula J, Isoaho N, Peltola E, Koehne J, Meyyappan M, Koskinen J, and Laurila T
- Subjects
- Biosensing Techniques methods, Dopamine metabolism, Electrochemical Techniques, Humans, Metals metabolism, Nanostructures chemistry, Neurotransmitter Agents metabolism, Carbon metabolism, Hydrogen Peroxide metabolism, Metal Nanoparticles, Nanotubes, Carbon chemistry
- Abstract
Age structure in most developed countries is changing fast as the average lifespan is increasing significantly, calling for solutions to provide improved treatments for age-related neurological diseases and disorders. In order to address these problems, a reliable way of recording information about neurotransmitters from in vitro and in vivo applications is needed to better understand neurological diseases and disorders as well as currently used treatments. Likewise, recent developments in medicine, especially with the opioid crisis, are demanding a swift move to personalized medicine to administer patient needs rather than population-wide averages. In order to enable the so-called personalized medicine, it is necessary to be able to do measurements in vivo and in real time. These actions require sensitive and selective detection of different analytes from very demanding environments. Current state-of-the-art materials are unable to provide sensitive and selective detection of neurotransmitters as well as the required time resolution needed for drug molecules at a reasonable cost. To meet these challenges, we have utilized different metals to grow carbon nanomaterials and applied them for sensing applications showing that there are clear differences in their electrochemical properties based on the selected catalyst metal. Additionally, we have combined atomistic simulations to support optimizing materials for experiments and to gain further understanding of the atomistic level reactions between different analytes and the sensor surface. With carbon nanostructures grown from Ni and Al + Co + Fe hybrid, we can detect dopamine, ascorbic acid, and uric acid simultaneously. On the other hand, nanostructures grown from platinum provide a feasible platform for detection of H
2 O2 making them suitable candidates for enzymatic biosensors for detection of glutamate, for example. Tetrahedral amorphous carbon electrodes have an ability to detect morphine, paracetamol, tramadol, and O-desmethyltramadol. With carbon nanomaterial-based sensors, it is possible to reach metal-like properties in sensing applications using only a fraction of the metal as seed for the material growth. We have also seen that by using nanodiamonds as growth catalyst for carbon nanofibers, it is not possible to detect dopamine and ascorbic acid simultaneously, although the morphology of the resulting nanofibers is similar to the ones grown using Ni. This further indicates the importance of the metal selection for specific applications. However, Ni as a continuous layer or as separate islands does not provide adequate performance. Thus, it appears that metal nanoparticles combined with fiber-like morphology are needed for optimized sensor performance for neurotransmitter detection. This opens up a new research approach of application-specific nanomaterials, where carefully selected metals are integrated with carbon nanomaterials to match the needs of the sensing application in question.- Published
- 2020
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17. Corrigendum to "Unmodified and multi-walled carbon nanotube modified tetrahedral amorphous carbon (ta-C) films as in vivo sensor materials for sensitive and selective detection of dopamine" [Bios. Bioelectron. 118 (2018) 23-30].
- Author
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Palomäki T, Peltola E, Sainio S, Wester N, Pitkänen O, Kordas K, Koskinen J, and Laurila T
- Published
- 2019
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18. Unmodified and multi-walled carbon nanotube modified tetrahedral amorphous carbon (ta-C) films as in vivo sensor materials for sensitive and selective detection of dopamine.
- Author
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Palomäki T, Peltola E, Sainio S, Wester N, Pitkänen O, Kordas K, Koskinen J, and Laurila T
- Subjects
- Animals, Ascorbic Acid, Electrodes, Mice, Uric Acid, Biosensing Techniques methods, Carbon chemistry, Dopamine analysis, Nanotubes, Carbon chemistry
- Abstract
Unmodified and multi-walled carbon nanotube (MWCNT) modified tetrahedral amorphous carbon (ta-C) films of 15 and 50 nm were investigated as potential in vivo sensor materials for the detection of dopamine (DA) in the presence of the main interferents, ascorbic acid (AA) and uric acid (UA). The MWCNTs were grown directly on ta-C by chemical vapor deposition (designated as ta-C+CNT) and were characterized with X-ray photoelectron spectroscopy, Raman spectroscopy, scanning and transmission electron microscopy. Electroanalytical sensitivity and selectivity were determined with cyclic voltammetry. Biocompatibility of the materials was assessed with cell cultures of mouse neural stem cells (mNSCs). The detection limits of DA for both ta-C and ta-C+CNT electrodes ranged from 40 to 85 nM, which are well within the required range for in vivo detection. The detection limits were lower for both ta-C and ta-C+CNT electrodes with 50 nm of ta-C compared to 15 nm. The ta-C electrodes showed a large dynamic linear range of 0.01-100 µM but could not resolve between the oxidation peaks of DA, AA and UA. Modification with MWCNTs, however, resulted in excellent selectivity and all three analytes could be detected simultaneously at physiologically relevant concentrations using cyclic voltammetry. Based on cell culture of mNSCs, both ta-C and ta-C+CNT exhibited good biocompatibility, demonstrating their potential as in vivo sensor materials for the detection of DA., (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
19. Electrochemical Fouling of Dopamine and Recovery of Carbon Electrodes.
- Author
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Peltola E, Sainio S, Holt KB, Palomäki T, Koskinen J, and Laurila T
- Subjects
- Adsorption, Amination, Electrodes, Implanted, Indoles analysis, Oxidation-Reduction, Polymers analysis, Surface Properties, Biosensing Techniques instrumentation, Carbon chemistry, Dopamine analysis, Electrochemical Techniques instrumentation
- Abstract
A significant problem with implantable sensors is electrode fouling, which has been proposed as the main reason for biosensor failures in vivo. Electrochemical fouling is typical for dopamine (DA) as its oxidation products are very reactive and the resulting polydopamine has a robust adhesion capability to virtually all types of surfaces. The degree of DA fouling of different carbon electrodes with different terminations was determined using cyclic voltammetry (CV) and scanning electrochemical microscopy (SECM) approach curves and imaging. The rate of electron transfer kinetics at the fouled electrode surface was determined from SECM approach curves, allowing a comparison of insulating film thickness for the different terminations. SECM imaging allowed the determination of different morphologies, such as continuous layers or islands, of insulating material. We show that heterogeneous modification of carbon electrodes with carboxyl-amine functionalities offers protection against formation of an insulating polydopamine layer, while retaining the ability to detect DA. The benefits of the heterogeneous termination are proposed to be due to the electrostatic repulsion between amino-functionalities and DA. Furthermore, we show that the conductivity of the surfaces as well as the response toward DA was recovered close to the original performance level after cleaning the surfaces for 10-20 cycles in H
2 SO4 on all materials but pyrolytic carbon (PyC). The recovery capacity of the PyC electrode was lower, possibly due to stronger adsorption of DA on the surface.- Published
- 2018
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20. Oligonucleotide-based pharmaceuticals: Non-clinical and clinical safety signals and non-clinical testing strategies.
- Author
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Mustonen EK, Palomäki T, and Pasanen M
- Subjects
- Animals, Guidelines as Topic, Humans, Kidney drug effects, Kidney metabolism, Liver drug effects, Liver metabolism, Mutagenicity Tests methods, Mutagenicity Tests standards, Oligonucleotides pharmacokinetics, RNA, Small Interfering pharmacokinetics, Species Specificity, Tissue Distribution, Drug-Related Side Effects and Adverse Reactions, Immune System drug effects, Oligonucleotides adverse effects, RNA, Small Interfering adverse effects
- Abstract
Antisense oligonucleotides, short interfering RNAs (siRNAs) and aptamers are oligonucleotide-based pharmaceuticals with a promising role in targeted therapies. Currently, five oligonucleotide-based pharmaceuticals have achieved marketing authorization in Europe or USA and many more are undergoing clinical testing. However, several safety concerns have been raised in non-clinical and clinical studies. Oligonucleotides share properties with both chemical and biological pharmaceuticals and therefore they pose challenges also from the regulatory point of view. We have analyzed the safety data of oligonucleotides and evaluated the applicability of current non-clinical toxicological guidelines for assessing the safety of oligonucleotide-based pharmaceuticals. Oligonucleotide-based pharmaceuticals display a similar toxicological profile, exerting adverse effects on liver and kidney, evoking hematological alterations, as well as causing immunostimulation and prolonging the coagulation time. It is possible to extrapolate some of these effects from non-clinical studies to humans. However, evaluation strategies for genotoxicity testing of "non-natural" oligonucleotides should be revised. Additionally, the selective use of surrogates and prediction of clinical endpoints for non-clinically observed immunostimulation is complicated by its multiple potential manifestations, demanding improvements in the testing strategies. Utilizing more relevant and mechanistic-based approaches and taking better account of species differences, could possibly improve the prediction of relevant immunological/proinflammatory effects in humans., (Copyright © 2017 Elsevier Inc. All rights reserved.)
- Published
- 2017
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21. Integrated Carbon Nanostructures for Detection of Neurotransmitters.
- Author
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Sainio S, Palomäki T, Tujunen N, Protopopova V, Koehne J, Kordas K, Koskinen J, Meyyappan M, and Laurila T
- Subjects
- Coated Materials, Biocompatible, Dopamine analysis, Equipment Design, Glutamic Acid analysis, Hydrogen-Ion Concentration, In Vitro Techniques, Silicon, Biosensing Techniques, Carbon chemistry, Electrochemical Techniques instrumentation, Electrodes, Nanofibers, Nanotubes, Carbon, Neurotransmitter Agents analysis
- Abstract
Carbon-based materials, such as diamond-like carbon (DLC), carbon nanofibers (CNFs), and carbon nanotubes (CNTs), are inherently interesting for neurotransmitter detection due to their good biocompatibility, low cost and relatively simple synthesis. In this paper, we report on new carbon-hybrid materials, where either CNTs or CNFs are directly grown on top of tetrahedral amorphous carbon (ta-C). We show that these hybrid materials have electrochemical properties that not only combine the best characteristics of the individual "building blocks" but their synergy makes the electrode performance superior compared to conventional carbon based electrodes. By combining ta-C with CNTs, we were able to realize electrode materials that show wide and stable water window, almost reversible electron transfer properties and high sensitivity and selectivity for detecting dopamine in the presence of ascorbic acid. Furthermore, the sensitivity of ta-C + CNF hybrids towards dopamine as well as glutamate has been found excellent paving the road for actual in vivo measurements. The wide and stable water window of these sensors enables detection of other neurotransmitters besides DA as well as capability of withstanding higher potentials without suffering from oxygen and hydrogen evolution.
- Published
- 2015
- Full Text
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22. Risk of tumorigenicity in mesenchymal stromal cell-based therapies--bridging scientific observations and regulatory viewpoints.
- Author
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Barkholt L, Flory E, Jekerle V, Lucas-Samuel S, Ahnert P, Bisset L, Büscher D, Fibbe W, Foussat A, Kwa M, Lantz O, Mačiulaitis R, Palomäki T, Schneider CK, Sensebé L, Tachdjian G, Tarte K, Tosca L, and Salmikangas P
- Subjects
- Adipose Tissue cytology, Bone Marrow Cells cytology, Cell Culture Techniques, Cell Differentiation genetics, Humans, Mesenchymal Stem Cells metabolism, Carcinogenesis, Cell Proliferation, Mesenchymal Stem Cell Transplantation adverse effects, Mesenchymal Stem Cells cytology
- Abstract
In the past decade, the therapeutic value of mesenchymal stromal cells (MSCs) has been studied in various indications, thereby taking advantage of their immunosuppressive properties. Easy procurement from bone marrow, adipose tissue or other sources and conventional in vitro expansion culture have made their clinical use attractive. Bridging the gap between current scientific knowledge and regulatory prospects on the transformation potential and possible tumorigenicity of MSCs, the Cell Products Working Party and the Committee for Advanced Therapies organized a meeting with leading European experts in the field of MSCs. This meeting elucidated the risk of potential tumorigenicity related to MSC-based therapies from two angles: the scientific perspective and the regulatory point of view. The conclusions of this meeting, including the current regulatory thinking on quality, nonclinical and clinical aspects for MSCs, are presented in this review, leading to a clearer way forward for the development of such products., (Copyright © 2013 International Society for Cellular Therapy. All rights reserved.)
- Published
- 2013
- Full Text
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23. Brain state-triggered stimulus delivery: An efficient tool for probing ongoing brain activity.
- Author
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Andermann ML, Kauramäki J, Palomäki T, Moore CI, Hari R, Jääskeläinen IP, and Sams M
- Abstract
What is the relationship between variability in ongoing brain activity preceding a sensory stimulus and subsequent perception of that stimulus? A challenge in the study of this key topic in systems neuroscience is the relative rarity of certain brain 'states'-left to chance, they may seldom align with sensory presentation. We developed a novel method for studying the influence of targeted brain states on subsequent perceptual performance by online identification of spatiotemporal brain activity patterns of interest, and brain-state triggered presentation of subsequent stimuli. This general method was applied to an electroencephalography study of human auditory selective listening. We obtained online, time-varying estimates of the instantaneous direction of neural bias (towards processing left or right ear sounds). Detection of target sounds was influenced by pre-target fluctuations in neural bias, within and across trials. We propose that brain state-triggered stimulus delivery will enable efficient, statistically tractable studies of rare patterns of ongoing activity in single neurons and distributed neural circuits, and their influence on subsequent behavioral and neural responses.
- Published
- 2012
24. Bacteriophage Mu integration in yeast and mammalian genomes.
- Author
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Paatero AO, Turakainen H, Happonen LJ, Olsson C, Palomäki T, Pajunen MI, Meng X, Otonkoski T, Tuuri T, Berry C, Malani N, Frilander MJ, Bushman FD, and Savilahti H
- Subjects
- Animals, Cell Line, Chromosome Mapping, Electroporation, Embryonic Stem Cells metabolism, Genetic Markers, Genome, Fungal, Genome, Human, Genomics, HeLa Cells, Humans, Mice, Saccharomyces cerevisiae genetics, Bacteriophage mu genetics, DNA Transposable Elements, Gene Transfer Techniques
- Abstract
Genomic parasites have evolved distinctive lifestyles to optimize replication in the context of the genomes they inhabit. Here, we introduced new DNA into eukaryotic cells using bacteriophage Mu DNA transposition complexes, termed 'transpososomes'. Following electroporation of transpososomes and selection for marker gene expression, efficient integration was verified in yeast, mouse and human genomes. Although Mu has evolved in prokaryotes, strong biases were seen in the target site distributions in eukaryotic genomes, and these biases differed between yeast and mammals. In Saccharomyces cerevisiae transposons accumulated outside of genes, consistent with selection against gene disruption. In mouse and human cells, transposons accumulated within genes, which previous work suggests is a favorable location for efficient expression of selectable markers. Naturally occurring transposons and viruses in yeast and mammals show related, but more extreme, targeting biases, suggesting that they are responding to the same pressures. These data help clarify the constraints exerted by genome structure on genomic parasites, and illustrate the wide utility of the Mu transpososome technology for gene transfer in eukaryotic cells.
- Published
- 2008
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25. Vibrotactile feedback for brain-computer interface operation.
- Author
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Cincotti F, Kauhanen L, Aloise F, Palomäki T, Caporusso N, Jylänki P, Mattia D, Babiloni F, Vanacker G, Nuttin M, Marciani MG, and Del R Millán J
- Abstract
To be correctly mastered, brain-computer interfaces (BCIs) need an uninterrupted flow of feedback to the user. This feedback is usually delivered through the visual channel. Our aim was to explore the benefits of vibrotactile feedback during users' training and control of EEG-based BCI applications. A protocol for delivering vibrotactile feedback, including specific hardware and software arrangements, was specified. In three studies with 33 subjects (including 3 with spinal cord injury), we compared vibrotactile and visual feedback, addressing: (I) the feasibility of subjects' training to master their EEG rhythms using tactile feedback; (II) the compatibility of this form of feedback in presence of a visual distracter; (III) the performance in presence of a complex visual task on the same (visual) or different (tactile) sensory channel. The stimulation protocol we developed supports a general usage of the tactors; preliminary experimentations. All studies indicated that the vibrotactile channel can function as a valuable feedback modality with reliability comparable to the classical visual feedback. Advantages of using a vibrotactile feedback emerged when the visual channel was highly loaded by a complex task. In all experiments, vibrotactile feedback felt, after some training, more natural for both controls and SCI users.
- Published
- 2007
- Full Text
- View/download PDF
26. The PmrA-PmrB two-component system responding to acidic pH and iron controls virulence in the plant pathogen Erwinia carotovora ssp. carotovora.
- Author
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Hyytiäinen H, Sjöblom S, Palomäki T, Tuikkala A, and Tapio Palva E
- Subjects
- Amino Acid Sequence, Anti-Bacterial Agents pharmacology, Bacterial Proteins genetics, Bacterial Proteins metabolism, Drug Resistance, Bacterial genetics, Gene Expression Regulation, Bacterial, Homeostasis, Hydrogen-Ion Concentration, Magnesium metabolism, Magnesium pharmacology, Molecular Sequence Data, Mutation, Operon, Pectobacterium carotovorum drug effects, Plant Diseases microbiology, Polymyxin B pharmacology, RNA-Binding Proteins genetics, RNA-Binding Proteins metabolism, Repressor Proteins genetics, Repressor Proteins metabolism, Sequence Homology, Amino Acid, Transcription Factors drug effects, Transcription Factors genetics, Virulence genetics, Iron pharmacology, Pectobacterium carotovorum pathogenicity, Pectobacterium carotovorum physiology, Transcription Factors metabolism
- Abstract
Efficient response to environmental cues is crucial to successful infection by plant-pathogenic bacteria such as Erwinia carotovora ssp. carotovora. The expression of the main virulence genes of this pathogen, encoding extracellular enzymes that degrade the plant-cell wall, is subject to complex regulatory machinery where two-component systems play an important role. In this paper, we describe for the first time the involvement of the PmrA-PmrB two-component system in regulation of virulence in a plant-pathogenic bacterium. Disruption of pmrB resulted in reduced virulence both in potato and in Arabidopsis. This is apparently due to reduced production of the extracellular enzymes. In contrast, a pmrA mutant exhibited increased levels of these enzymes implying negative regulation of the corresponding genes by PmrA. Furthermore, the pmrB but not pmrA mutant exhibited highly increased resistance to the cationic antimicrobial peptide polymyxin B suggesting alterations in cell surface properties of the mutant. A similar increase of polymyxin resistance was detected in the wild type at mildly acidic pH with low Mg2+. Functional pmrA is essential for bacterial survival on excess iron at acidic pH, regardless of the Mg2+ concentration. We propose that PmrA-PmrB TCS is involved in controlling of bacterial response to external pH and iron and is crucial for bacterial virulence and survival in planta.
- Published
- 2003
- Full Text
- View/download PDF
27. A putative three-dimensional targeting motif of polygalacturonase (PehA), a protein secreted through the type II (GSP) pathway in Erwinia carotovora.
- Author
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Palomäki T, Pickersgill R, Riekki R, Romantschuk M, and Saarilahti HT
- Subjects
- Amino Acid Motifs, Models, Molecular, Mutation, Pectobacterium carotovorum chemistry, Polygalacturonase metabolism, Protein Conformation, Pectobacterium carotovorum metabolism, Polygalacturonase chemistry, Polygalacturonase genetics
- Abstract
Intramolecular information specifying protein secretion through the type II (GSP) pathway of Gram-negative bacteria was investigated. Two regions of the polygalacturonase (PehA) of Erwinia carotovora containing residues proposed to be included in a targeting motif were located, one close to the C-terminus between residues 342 and 369 and another between residues 84 and 135 in the large central loops. The regions were required together to promote secretion. Further residues in the middle of the protein were required for proper positioning of the regions, suggesting that they were both involved in interaction with the GSP. To our knowledge, this is the first time that a possible three-dimensional targeting motif has been defined. At least one of the motifs comprises a cluster on the surface of the protein. The two motifs are structurally dissimilar, suggesting that there are two distinct recognition regions in the GSP apparatus. Finally, we propose that the targeting motifs are of a complex conformational nature with some variability accommodated, as illustrated by the observation that many mutations exhibited no clear phenotype individually but, in combination, severely compromised secretion.
- Published
- 2002
- Full Text
- View/download PDF
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