The prolonged hematologic effects of a single injection of PEG-rHuMGDF in normal and thrombocytopenic mice

A single injection of > or =10 microg/kg PEG-rHuMGDF in mice causes a dose-dependent increase in circulating platelets beginning on day 3 and peaking on days 5-6. The mean platelet volume and platelet distribution width at doses > or =100 microg/kg initially increase in a dose-dependent fashion and later decrease. However, the mean platelet volume does not change when platelets are incubated with PEG-rHuMGDF in vitro. The number of marrow megakaryocytes increases in a dose-dependent fashion as early as day 1 and peaks on day 3. Marrow megakaryocyte colony-forming units (CFU-Meg) do not increase on days 1-3 at a dose of 100 microg/kg (a dose that increases platelet numbers two- to threefold and may be clinically relevant), but the relative frequency of high ploidy megakaryocytes and the proportion of large marrow megakaryocytes (29-50 microm in diameter) increases. After a dose of 1,000 microg/kg the percentage of megakaryocytes in mitosis peaks at 24-48 hours and the percentage of megakaryocytes incorporating BrdU is maximal at 48 hours, the relatively delayed peak of BrdU incorporation most likely representing endomitosis. The relative frequency of type II and III megakaryocytes peaks on days 3 and 4, respectively. Pharmacokinetic analysis of PEG-rHuMGDF shows peak serum concentrations at 2-4 hours and a terminal half-life of 11.4+/-2.5 hours. A single injection of PEG-rHuMGDF ameliorates carboplatin-induced megakaryocytopenia and thrombocytopenia in a dose-response dependent fashion. In conclusion, a single injection of PEG-rHuMGDF increases megakaryocyte and platelet production in normal and myelo-suppressed mice.     

Generation of terahertz electromagnetic pulses from quantum-wellstructures

Terahertz generation from semiconductor quantum-well structures pumped by a femtosecond optical pulse is studied. We propose a three-level model for the electrons and holes in the quantum wells. We then solve the coupled optical Bloch equations directly using a Runge-Kutta method and calculate the terahertz radiation field. We study optical rectification and quantum beats caused by charge oscillations in 1) a coupled quantum well in which quantum beats occur between two electron states of the coupled system and 2) a single-quantum-well structure in which quantum beats occur between light-hole and heavy-hole excitons. Our theoretical results agree very well with the experimentally measured terahertz data     

A study of reversibly inactivated lipases for use in a morphine-triggered naltrexone delivery system

A key component of an implant that can be triggered by external morphine to release naltrexone is an inactivated enzyme that can be activated by morphine and which can then rapidly remove a protective coating surrounding a bioerodible polymer containing dispersed naltrexone. In this article we describe a lipase that has been conjugated with O3-carboxymethylmorphine, morphine-beta-3-glucuronide and O3-carboxypropylmorphine. The enzyme conjugate was then inactivated by complexation with affinity-purified goat polyclonal antimorphine antibodies. Antibody lipase interactions were measured by pH Stat and ELISA techniques. Affinity constants of the antibodies determined by radioimmunoassay using tritium-labeled morphine were 4.10 x 10(6), 3.18 x 10(6) and 3.38 x 10(7), respectively. While a concentration of 10(-5)M morphine was required to restore lipase activity, it is likely that a combination of correct morphine tether and correct affinity-purified antibody can increase sensitivity to the desired 10(-8)10(-9)M morphine level. Thus, a functioning device can almost certainly be constructed. However, it is unlikely that reactivation times of 1-2 h necessary for clinical usefulness in treatment of narcotic addiction can be achieved.     

Imaging and Spectroscopic Sensing with Low-Repetition-Rate Terahertz Pulses and GaN TeraFET Detectors

Aiming for non-destructive testing and security applications, we investigate transmission-mode imaging and spectroscopic sensing using terahertz (THz) pulses from a commercial optical parametric oscillator (OPO) in combination with THz detectors based on antenna-coupled field-effect transistors (TeraFETs). The Q-switched OPO generates quasi-continuous-wave THz pulses with a peak power of up to 1 W at a repetition rate between 12 and 90 Hz. The pulses are frequency-tunable between 0.7 and 2.6 THz with a typical linewidth of 50 GHz. We explore detection with fast GaN/AlGaN TeraFETs which hold the potential for multi-pixel and homodyne detection.     

Fast Active THz Cameras with Ranging Capabilities

We report on the realization of two active, fully electronic THz cameras, both operating at room temperature, but at different frequencies (645 GHz and 300 GHz, respectively). Active illumination together with the frequency-modulated-continuous-wave (FMCW) approach allows us to implement unique features such as phase-sensitive detection, suppression of spurious reflections and high resolution ranging. The measuring of the phase of the THz wave allows for sub-wavelength depth resolution while the ranging capabilities enable us to acquire an absolute depth map of objects under test with accuracy in the mm range. With both systems, we are able to acquire images with more than 55,000 pixels (phase and amplitude) in 9 seconds and the dynamic range exceeds 35 dB. The typical object distance is about 75–150 cm and the image size is in the order of hundreds of cm² suitable for stand off detection of concealed weapons.     

All-Optoelectronic Terahertz Imaging Systems and Examples of Their Application

We give an overview over several all-optoelectronic measurement systems which we have developed for transmittive and reflective imaging in the terahertz (THz) frequency range. The systems employ either pulsed or continuous-wave THz radiation. In both cases, they work on the basis of single-pixel scanning. Addressing the potential for imaging in the medical and dental field, and the application of THz radiation for industrial surface and interface characterization, we explore dark-field imaging where the imaging contrast originates from diffraction and scattering effects coming from topography or refractive-index variations.