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S Nurmenniemi,
P Kuvaja,
S Lehtonen, S Tiuraniemi,
I Alahuhta,
R K Mattila,
J Risteli,
T Salo,
K S Selander,
P Nyberg,
P Lehenkari
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ABSTRACT: Human mesenchymal stem cells (hMSCs) are multipotent cells that are found in the bone marrow. Inflammation and tissue damage mobilize MSCs and induce their migration towards the damaged site through mechanisms that are not well defined. Toll-like receptor-9 (TLR9) is a cellular receptor for microbial and vertebrate DNA. Stimulation of TLR9 induces inflammatory and invasive responses in TLR9-expressing cells. We studied here the expression of TLR9 in human MSCs and the effects of synthetic TLR9-agonists on their invasion. Constitutive expression of TLR9 was detected in human MSCs but the expression was suppressed when MSCs were induced to differentiate into osteoblasts. Using standard invasion assays and a novel organotypic culture model based on human myoma tissue, we discovered that stimulation with the TLR9 agonistic, CpG oligonucleotides increased the invasion capacity of undifferentiated MSCs. Simultaneously, an increase in MMP-13 synthesis and activity was detected in the CpG-activated MSCs. Addition of anti-MMP-13 antibody significantly diminished the CpG-induced hMSC invasion. We conclude that treatment with TLR9-ligands increases MSC invasiveness, and this process is at least partially MMP-13-mediated.
Experimental Cell Research 10/2010; 316(16):2676-82. · 3.58 Impact Factor
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ABSTRACT: In this paper, the architecture of a non-coherent low-complexity ultra wideband impulse radio (UWB-IR) transceiver architecture for low data rate, low complexity tag based sensor networks is presented. The UWB-IR receiver utilises a non-coherent, energy detection-based approach, which makes it largely independent of the shape of the transmit waveform and robust to multipath channels. The UWB-IR transmitter utilises a delay locked loop (DLL) frequency synthesis approach and UWB monocycle pulse generator. The UWB-IR ASIC is manufactured in 0.35 μm SiGe BiCMOS technology. The simulated power consumption of UWB-IR transceiver circuits is 136 mW with 100% duty cycle with a 3.3 V power supply.
Ultra-Wideband, 2005. ICU 2005. 2005 IEEE International Conference on; 10/2005
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ABSTRACT: An ultrawide band front-end receiver for low power, low complexity communications system is designed and simulated. The receiver consists of an ultra wideband antenna, band-pass filter, low noise amplifier, variable gain amplifier, a Gilbert mixer for squaring and an integrator used for integrating the squared signal. The receiver is based on a non-coherent, energy collection approach, which makes the receiver highly independent of the shape of the received waveform. The bandwidth of the used signal in the system is 1 GHz at 3.1 GHz - 4.1 GHz which is attained by filtering the transmitted signal before and after antenna in transmitter and receiver, respectively. The design is made using a SiGe 0.35 μm BiCMOS process provided by Austria Microsystems.
Ultra-Wideband, 2005. ICU 2005. 2005 IEEE International Conference on; 10/2005
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ABSTRACT: The architecture of a low-power, low-complexity ultra wideband (UWB) impulse radio (IR) transceiver circuit, aimed for low data rate, low-cost applications, is presented. The UWB-ER receiver is based on a non-coherent, energy-based approach, which makes it largely independent of the shape of the transmit waveform and robust to multipath channels. Both transmitter and receiver functionalities are included in the circuit presented. The circuits are designed for 0.35 μm CMOS IC technology, and the top-level layout of the transmitter is given. The UWB pulse generator produces a Gaussian monocycle of 340 ps typical width. The UWB-IR transmitter IC occupies a total area of 0.16 mm<sup>2</sup>, and consumes 20 mW with a 3.3 V supply.
Circuits and Systems, 2005. ISCAS 2005. IEEE International Symposium on; 06/2005
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ABSTRACT: The paper presents the architecture of a low power, low complexity ultra wideband (UWB) transceiver circuit. The circuit is designed for low data rate, low cost applications with built in location and tracking capabilities. The system is based on a non-coherent architecture which enables the receiver to be extremely simple and largely insensitive to the transmitted pulse shape. The circuit presented contains the oscillator, the transmitter, the receiver and the baseband digital signal processing (DSP) block. The oscillator contains the quartz oscillator, a delay locked-loop (DLL) and edge combiner for clock multiplication to generate a 528 MHz timing signal for pulse generation. The transmitter contains a second DLL to fix the delay of the UWB pulse, the UWB pulse generator and antenna. The transmitted UWB pulse is presented. The receiver contains low noise amplifier, variable gain amplifier, squaring circuits, integrators for energy collection, 4 bit analogue-to-digital converters (ADC), digital control logic, integrator and gain selection logic block and detection/bit decision block. The circuits are designed in a 0.35 μm Si-Ge BiCMOS process from Austria Microsystems.
Personal, Indoor and Mobile Radio Communications, 2004. PIMRC 2004. 15th IEEE International Symposium on; 10/2004
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ABSTRACT: The paper presents the architecture of a low power, low complexity ultra wideband (UWB) transceiver circuit. The circuit is designed for low data rate, low cost applications with built in location and tracking. The system is based on a non-coherent architecture which enables the receiver to be extremely simple and largely insensitive to the transmitted pulse shape. The circuit presented contains the oscillator generator, the transmitter, the receiver and baseband digital signal processing (DSP) block. The oscillator generator contains the quartz oscillator, a delay-locked loop (DLL) and edge combiner for clock multiplication to generate a 495 MHz timing signal for pulse generation. The transmitter contains a second DLL (to fix the UWB pulse delay), UWB pulse generator and antenna. The 495 MHz RF signal together with the transmitted UWB pulse are presented. The receiver contains low noise amplifier, variable gain amplifier, squaring circuits, integrators for energy collection, 4 bit A/D converters, digital control logic, integrator and gain selection logic block and detection/bit decision block. The circuits are designed in a 0.35 μm Si-Ge BiCMOS process from Austria Microsystems. The UWB TAG is not yet manufactured.
Ultra Wideband Systems, 2004. Joint with Conference on Ultrawideband Systems and Technologies. Joint UWBST & IWUWBS. 2004 International Workshop on; 06/2004
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ABSTRACT: This paper presents a sensor network with low power, low cost devices based on UWB technology employing TDMA. The low data rate network (of the order of 1 kbs-100 kbps per user) is described which also offers good location and tracking capabilities. The UWB tags consist of low power, low-cost, low-complexity transceivers which operate in conjunction with a number of fixed sensor nodes which calculate the tag position. This paper presents the system concept, UWB transceiver and performance in a multipath environment. Location and tracking is not specifically dealt with in this paper.
Wireless Ad-Hoc Networks, 2004 International Workshop on;
