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71.
The complete profile of 8-methoxypsoralen photoadduct formation in complementary oligonucleotides (5'-GAGTATGAG and 5'-CATAC) has been determined. Equimolar solutions of the oligonucleotides were irradiated at 4 degrees C in order to stabilize the mini-double helix. Photomodified oligonucleotides were separated by reversed phase chromatography on a Vydac C4 column. Photoadduct formation favored the 5'TAT site in the 9mer over the 5'ATA site in the 5mer by a factor of two. Split-dose studies showed that the monoadducts formed on GAGTATGAG were preferentially converted to cross-links by an additional UVA exposure. 相似文献
72.
TE Williams CK Meshul NJ Cherry NM Tiffany FP Eckenstein WR Woodward 《Canadian Metallurgical Quarterly》1996,370(2):147-158
Basic fibroblast growth factor (bFGF), a member of the heparin-binding growth factor family, is present in relatively high levels in the brain where it may play an important role in the maintenance, repair, and reorganization of the tissue. Although bFGF is associated mainly with astrocytes throughout most of the central nervous system (CNS), a narrow but prominent band of pyramidal neurons, which coincides with the CA2 subregion of Ammon's horn in the hippocampus, stains intensely for bFGF. In order to gain an understanding of which cells express bFGF and whether or not BFGF is a good marker for CA2 neurons, we have used a mouse monoclonal antibody directed against recombinant human bFGF to characterize the distribution and localization of bFGF expression in the hippocampus. We find that about one-quarter of the neurons in CA2 are bFGF positive, and they appear smaller and have more irregular-shaped nuclei than their unstained counterparts. In addition, all glial fibrilary acidic protein (GFAP)-positive astrocytes in the hippocampus stain for bFGF, and the distribution of these astrocytes is heterogeneous in the hippocampus. Finally, in both astrocytes and CA2 pyramidal neurons, bFGF immunoreactivity is localized primarily in the nucleus and to a lesser extent in the cytoplasm and processes of stained cells. 相似文献
73.
AJ Van Oosterhout B Van Esch G Hofman CL Hofstra I Van Ark FP Nijkamp ML Kapsenberg HF Savelkoul FR Weller 《Canadian Metallurgical Quarterly》1998,19(4):622-628
Microelectrode recording methods for stereotactic localization of the subthalamic nucleus (STN) and surrounding structures are described. These methods accurately define targets for chronic deep brain stimulation in the treatment of Parkinson's disease. Mean firing rates and a burst index were determined for all recorded neurons, and responses to active and passive limb and orofacial movements were tested. STN neurons had a mean firing rate of 37+/-17 Hz (n = 248) and an irregular firing pattern (median burst index, 3.3). Movement-related activity and tremor cells were identified in the STN. Ventral to the STN, substantia nigra pars reticulata neurons had a mean rate of 71+/-23 Hz (n = 56) and a more regular firing pattern (median burst index, 1.7). Short trains (1-2 seconds) of electrical microstimulation of STN could produce tremor arrest but were not found to be useful for localization. Compared with data from normal monkeys our findings suggest that STN neuronal activity is elevated in Parkinson's disease. 相似文献
74.
This study evaluates the nature of glycated human insulin formed following exposure to hyperglycemic conditions in vitro. Glycated insulin was purified by RP-HPLC and its molecular mass (5971.3 Da) determined by plasma desorption mass spectrometry (MS). The difference in mass (163.7 Da) from nonglycated insulin (5807.6 Da) corresponds to a single reduced glucose (glucitol) residue. Following reduction of insulin disulfide bridges, MS confirmed that the B-chain was glycated. Enzymatic digestions with trypsin, endoproteinase Glu-C, and thermolysin, followed by RP-HPLC and identification of fragments by MS, localized glycation to the B-chain (1-5) region. Electrospray tandem MS identified the site of glycation as the B-chain NH2-terminal Phe1 residue. This was confirmed by automated Edman degradation with glycated human insulin. 相似文献
75.
76.
EM Hessel A Zwart E Oostveen AJ Van Oosterhout DI Blyth FP Nijkamp 《Canadian Metallurgical Quarterly》1995,79(5):1711-1716
A noninvasive forced oscillation technique was used to determine respiratory function in unanesthetized and spontaneously breathing mice. Pseudorandom noise pressure variations in a frequency range of 16-208 Hz were applied to the body surface, and the flow response was measured at the nose. From the pressure-flow relationship, respiratory transfer impedance was calculated. Study of intra-animal variability on a short- and a long-term basis revealed that the real part of respiratory transfer impedance was reproducible within 9%. The imaginary part appeared less reproducible (within 22%). Furthermore, bronchoconstrictive responses were investigated and analyzed by evaluation of respiratory resistance as measured at 16 Hz (Rrs16). During the first 15 min after ovalbumin challenge in ovalbumin-sensitized mice, Rrs16 was significantly increased [49 +/- 7% (SE)]. Inhalation of methacholine in untreated mice induced an increase in Rrs16 of 75 +/- 16% (SE). In saline-challenged animals, no significant changes were observed. This method enables evaluation of long-term respiratory function in mice and appeared to be a sensitive measure for bronchoconstriction. 相似文献
77.
FP Maesen SJ Smeets MA Costongs PG Zweers JP Pfeil 《Canadian Metallurgical Quarterly》1995,49(6):294-296
Fluorescence microscopy of caudal epididymal spermatozoa stained with 3, 3' dihexyloxacarbocyanine iodide (DiOC6(3)) showed intense fluorescence along the concave surface of the apical hook of spermatozoa of Rattus species and along the upper concave margin of the sperm head in Mus musculus. In the spermatozoa of Hydromys chrysogaster, Melomys cervinipes, and Pseudomys australis, the two ventral processes also fluoresced brightly. In P. australis, fluorescence in the apical hook of sperm heads was largely localized to its upper and lower surfaces. The sperm of N. alexis did not show consistent positive fluorescence. The localization of fluorescence in these spermatozoa after staining with DiOC6(3) was mainly restricted to regions where a large accumulation of perinuclear theca material lies beneath the plasmalemma. The reason for this remains to be determined, but DiOC6(3) may be useful for quickly demonstrating areas of abundant perinuclear thecal material in sperm heads of eutherian mammals by light microscopy. 相似文献
78.
George A. King Mayhew J. Ridge Graham S. Walker 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1975,25(10):721-726
A study was made of the effects of variations in concentration (0.125–0.75 saturated) and temperature (3–50°C) on the amounts of sodium incorporated in crystals of calcium sulphate dihydrate formed by the hydration of calcium sulphate hemihydrate in solutions of sodium chloride. The incorporation of sodium was favoured by reducing the temperature and increasing the concentration of sodium chloride. Samples of dihydrate containing sodium gave X-ray diffraction patterns with additional peaks that were attributed to the presence of a compound of calcium sulphate containing sodium but resembling the hemihydrate crystallographically. This compound appeared to occur as inclusions within the grains of dihydrate. 相似文献
79.
The authors describe an expert system, the Specification-Transformation Expert System (STES), which is to translate requirements specifications into design specifications automatically during the development phase of the software life cycle. STES accepts as input a software-requirements specification expressed in terms of dataflow diagrams. Using rules that embody a structured design methodology, STES translates this specification into a template describing a structure chart. STES consist of a knowledge base and an inference engine. The knowledge base contains information on the structured-design methodology and heuristic guidelines to help determine when certain methods should be applied. Given a target software system's requirements specification, the STES inference engine can perform intelligent decision-making and determine a suitable architectural design specification for the software system being designed. STES was originally implemented in OPS5 on a VAX11/780 computer. It has since been ported to an Apollo DN 3000 workstation and integrated with a commercial CASE tool 相似文献
80.