Medical image matching-a review with classification

A classification scheme for multimodal image matching is considered. The scope of the classification is restricted to methods that register data after acquisitions. The classification scheme may be used for any modality; not only for (2-D) projection images and (3-D) tomographic images, but also for other signal modalities that provide spatial insight into function or anatomy, e.g., EEG (electroencephalography) or MEG (magnetoencephalography) and for the real physical patient. The available literature on image matching is discussed and classified     

Biological applications of near-field optical microscopy

Presents several biological applications of near field optical microscopy, in combination with force microscopy. Aperture near field scanning optical microscopy (NSOM) with fluorescence detection gives (bio)chemical specificity and orientational information, in addition to the simultaneously acquired force image. This technique has large potential for DNA sequencing, molecular organization in monolayers, and study of the role of the cytoskeleton in cellular mobility in cell growth, cell migration, formation of protrusions, etc. Fluorescence NSOM gives high resolution on flat, not too deep surfaces. Fluorescence NSOM induces virtually no bleaching, as opposed to confocal fluorescence microscopy. Bright field NSOM in transmission generally yields a complicated contrast, caused by a mixture of dielectric and topographic contributions. Shear force feedback is essential in aperture NSOM operation with fibers, and operates on soft surfaces of cells and chromosomes. Ultimately, aperture NSOM is limited by low efficiency with a source brightness of typically 100 pW to 10 nW. Thus, in spectroscopic applications (fluorescence, Raman, etc.) photon noise will be a fundamental limit in the speed of imaging. Photon tunneling in combination with force microscopy allows routine scanning with a high optical lateral resolution. However, interference effects can be dominant on surfaces which display extensive scattering. As such, the application potential of PSTM to biological surfaces is rather limited. Clearly, the virtues of optics, non-invasiveness, high spectral resolution, and high time resolution all apply to the near field optical domain with its high spatial resolution, which adds extensively to the potential of scanning probe microscopy     

Nonequilibrium Thermodynamics of Mesoscopic Systems

The Markovian dynamics of a Brownian particle is derived in the case that the local temperature is a stochastic variable. The isolated mesoscopic particle plus environment system is analyzed in the microcanonical ensemble by means of nonlinear-process projection methods. The ensuing generalized Kramers FokkerPlanck equation involves a thermodynamic potential of mean force that is different from the canonical free energy, and the conditional entropy (or availability) emerges as the relevant steady-state potential. By coupling the system to a heat bath, we provide a microscopic foundation for the phenomenological theory of nonisothermal activation in mesoscopic systems. In the second part of this article, we then prove the existence of an availability potential governing the nonisothermal features of a Josephson junction in a SQUID, by studying the Josephson internal energy (and entropy) for T T _c in a model of two BCS superconductors coupled by a tunneling Hamiltonian. The predicted periodic dependence of the junction's T _c as a function of the flux in the SQUID has meanwhile been confirmed experimentally.     

Direct sequencing of neuropeptides in biological tissue by MALDI-PSD mass spectrometry

Dissected tissue pieces of the pituitary pars intermedia from the amphibian Xenopus laevis was directly subjected to matrix-assisted laser desorption/ionization (MALDI) mass analysis. The obtained MALDI peptide profile revealed both previously known and unexpected processing products of the proopiomelanocortin gene. Mass spectrometric peptide sequencing of a few of these neuropeptides was performed by employing MALDI combined with postsource decay (PSD) fragment ion mass analysis. The potential of MALDI-PSD for sequence analysis of peptides directly from unfractionated tissue samples was examined for the first time for the known desacetyl-alpha-MSH-NH2 and the presumed vasotocin neuropeptide. In addition, the sequence of an unknown peptide which was present in the pars intermedia tissue sample at mass 1392.7 u was determined. The MALDI-PSD mass spectrum of precursor ion 1392.7 u contained sufficient structural information to uniquely identify the sequence by searching protein sequence databases. The determined amino acid sequence corresponds to the vasotocin peptide with a C-terminal extension of Gly-Lys-Arg ("vasotocinyl-GKR"), indicating incomplete processing of the vasotocin precursor protein in the pituitary pars intermediate of X. laevis. Both vasotocin and vasotocinyl-GKR are nonlinear peptides containing a disulfide (S-S) bridge between two cysteine residues. Interpretation of the spectra of these two peptides reveals three different forms of characteristic fragment ions of the cysteine side chain: peptide-CH2-SH (regular mass of Cys-containing fragment ions), peptide-CH2-S-SH (regular mass + 32 u) and peptide = CH2 (regular mass -34 u) due to cleavage on either side of the sulfur atoms.     

Tyrosine-dependent and -independent mechanisms of STAT3 activation by the human granulocyte colony-stimulating factor (G-CSF) receptor are differentially utilized depending on G-CSF concentration

The granulocyte colony-stimulating factor receptor (G-CSF-R) activates multiple STAT proteins. Although the membrane-proximal cytoplasmic region of the G-CSF-R is necessary and sufficient for activation of STAT1 and STAT5, activation of STAT3 requires the membrane distal region that contains four tyrosines. Although one of these (Y704) has previously been shown to be involved in STAT3 activation from a truncated G-CSF-R derived from a patient with severe chronic neutropenia (SCN), this tyrosine is not required for STAT3 activation by the full-length G-CSF-R. To investigate possible alternative mechanisms of STAT3 activation, we generated a series of Ba/F3 cell transfectants expressing the wild-type G-CSF-R or mutant receptors that either completely lack tyrosines or retain just one of the four cytoplasmic tyrosines of the G-CSF-R. We show that, at saturating G-CSF concentrations, STAT3 activation from the full-length G-CSF-R is efficiently mediated by the C-terminal domain in a manner independent of receptor tyrosines. In contrast, at low G-CSF concentrations, Y704 and Y744 of the G-CSF-R play a major role in STAT3 activation. Both tyrosine-dependent and -independent mechanisms of STAT3 activation are sensitive to the Jak2 inhibitor AG-490, follow similar kinetics, and lead to transactivation of a STAT3 reporter construct, indicating functional equivalence. STAT3 activation is also impaired, particularly at nonsaturating G-CSF concentrations, in bone marrow cells from mice expressing a truncated G-CSF-R (gcsfr-triangle up715). These findings suggest that G-CSF-induced STAT3 activation during basal granulopoiesis (low G-CSF) and "emergency" granulopoiesis (high G-CSF) are differentially controlled. In addition, the data establish the importance of the G-CSF-R C-terminus in STAT3 activation in primary cells, which has implications for understanding why truncated G-CSF-R derived from SCN patients are defective in maturation signaling.     

Elderly and young driver's reaction to an in-car enforcement and tutoring system

A system that contrasts driver behaviour with normative behaviour was tested in an advanced driving simulator. Drivers were provided with auditory and visual tutoring messages if deviations were detected from normative, i.e. legally allowed behaviour with respect to a selection of offences. Results showed that the system was very effective in increasing law-abiding behaviour, which has a major positive effect on traffic safety. However, driver mental effort, as indicated by self-reports and drivers' physiological states, was slightly increased in conditions where drivers received feedback. Opinion about the tutoring system was positive in terms of usefulness. Self-reports on satisfaction differed between age groups; young drivers rated it low, while elderly drivers held a positive attitude.     

Characterization of the Hansenula polymorpha CPY gene encoding carboxypeptidase Y

We have isolated the Hansenula polymorpha CPY gene encoding carboxypeptidase Y (Hp-CPY). The deduced amino acid sequence revealed that Hp-CPY consists of 541 amino acids and has a calculated Mr of 60,793. The protein is highly similar to Saccharomyces cerevisiae CPY (61.8% identity). At the N-terminus of Hp-CPY signals for the entry into the secretory pathway and subsequent sorting to the vacuole were identified. Immunocytochemically, using monospecific antibodies raised against Hp-CPY, the protein was localized to the vacuole. On Western blots, a diffuse protein band was observed in extracts of H. polymorpha cells, suggesting that the protein is glycosylated. This was confirmed by endoglycosidase H treatment, which resulted in a strong reduction of the apparent Mr of the protein. We have investigated the effect of CPY deletion on the degradation of peroxisomes, an autophagous process that occurs when the organelles become redundant for growth. In deltacpy cells peroxisomal proteins were degraded in the vacuole as efficiently as in wild-type H. polymorpha cells, indicating that CPY is not a major proteinase in this pathway.     

Electrodeposition of PbO2 and Bi–PbO2 on Ebonex

Electrodeposition of PbO2 and Bi–PbO2 on Ebonex was carried out under various conditions, and the surfaces and coating/substrate interfaces examined by SEM, XPS and SIMS. Excellent adhesion to Ebonex was obtained with both crystalline and amorphous surfaces. Low plating temperatures resulted in dark grey, bright PbO2 and black, mirror-like Bi–PbO2 surfaces. Extrapolation of electrode lifetime test data indicated corrosion rates of 716 m yr–1 for PbO2 and 158 m yr–1 for Bi–PbO2.     

Passively Q-switched 1.57-microm intracavity optical parametric oscillator

We demonstrate an eye-safe KTP-based optical parametric oscillator (OPO) driven intracavity by a diode-pumped 1064-nm Nd:YAG laser, passively Q-switched by a Cr4+:YAG crystal. The characteristics of this system, which operates at 1570 nm with a repetition rate as high as 50 Hz, are studied as a function of Cr4+:YAG optical density. Under optimum conditions the OPO generates 1.5-mJ, 3.4 +/- 0.1-ns pulses in a single transverse mode. For a Cr4+:YAG Q-switch element with an optical density of 0.5 the conversion efficiency of the intracavity energy is approximately 45% with the ratio of OPO to Nd:YAG peak-pulse intensity exceeding unity. These and other OPO characteristics compare favorably with a simple rate equation model of the OPO dynamics.