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  • 11
    Electronic Resource
    Electronic Resource
    Synthesis and Processing of Doped Hg1Ba2Ca2Cu3O y Superconductors (1998)
    Springer
    Journal of superconductivity 11 (1998), S. 595-602 
    Details
    ISSN: 1572-9605
    Keywords: Hg1Ba2Ca2Cu3O y ; processing microstructure ; superconductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A series of quenching experiments were conducted to understand the sequence of reactions that occur during the synthesis of doped Hg1223, (Hg, A)Ba2Ca2Cu3O y , A = Re, Bi, and Pb (HgA1223). The formation and decomposition of the intermediate phases during the high-temperature reaction were followed as a function of temperature. HgA1223 phase forms over a wide range of temperatures, 750–950°C, 750–880°C, and 840–880°C for A = Re, Pb, and Bi, respectively. At T〈750°C, HgA1212 phase forms for A = Re and Pb. Based on the results of quenching experiments, heat treatment conditions were optimized for the synthesis of pure HgA1223 phase using commercial BaCaCuO precursor powders. A reduced-temperature annealing stage after the high-temperature reaction helps in grain growth and improves the microstructural characteristics of HgA1223 samples. Control of Hg pressure during the reaction is crucial for achieving phase purity, grain growth, and texture in the final products. A novel approach for the control of Hg pressure during the synthesis of HgA1223, which consists of using CaHgO2 as an external Hg source, is reported. HgA1223 samples synthesized using the new synthesis protocol exhibit improved microstructural and superconducting properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022687313287
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  • 12
    Electronic Resource
    Electronic Resource
    Accelerated gastric emptying of glucose in Zucker type 2 diabetic rats: role in postprandial hyperglycaemia (1997)
    Springer
    Diabetologia 40 (1997), S. 136-142 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Cholecystokinin ; secretin ; trypsin inhibitor ; glycaemic control ; gastric emptying.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Patients with early non-insulin-dependent diabetes mellitus (NIDDM) empty glucose solutions from their stomachs more rapidly than non-diabetic control subjects, and this exacerbates postprandial hyperglycaemia.To determine if accelerated gastric emptying occurred in a rat model of NIDDM and influenced postprandial hyperglycaemia, gastric emptying of glucose was measured, and the effect of slowing the gastric emptying rate on postprandial hyperglycaemia was observed. We tested eight male obese Zucker diabetic rats and eight age-matched lean Zucker controls at 10–13 weeks of age to measure gastric emptying of glucose (by gamma scintigraphy). Rats fasted overnight were gavaged with 30 % glucose at 1 ml/100 g body weight. Separately, six Zucker diabetic rats and six lean controls were tested for sensitivity to the inhibitory effects of cholecystokinin and secretin on gastric emptying. The diabetic rats emptied glucose significantly faster than controls (t1/2 = 37.3 ± 1.5 vs 58.8 ± 2.3 min in controls), and aging exaggerated this differential. Camostat, a stimulant of cholecystokinin and secretin release, added to the glucose meal significantly slowed gastric emptying (t1/2 = 123 ± 23 and 166 ± 19 min, diabetic vs lean, respectively), and significantly reduced postprandial hyperglycaemia in diabetic rats. Compared to Zucker lean controls, Zucker diabetic rats were as sensitive (cholecystokinin) or more sensitive (secretin) to gastrointestinal hormones that inhibit gastric emptying. The results demonstrate accelerated gastric emptying in a rat model of NIDDM, consistant with similar observations in humans with early NIDDM. These results also support the proposal that interventions to slow gastric emptying may improve glucose control in this disease. [Diabetologia (1997) 40: 136–142]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250050654
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  • 13
    Electronic Resource
    Electronic Resource
    Building a secretory apparatus: role of ARF1/COPI in Golgi biogenesis and maintenance (1998)
    Springer
    Histochemistry and cell biology 109 (1998), S. 449-462 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The secretory apparatus within all eukaryotic cells comprises a dynamic membrane system with bidirectional membrane transport pathways and overlapping compartmental boundaries. Membrane traffic and organelle biogenesis/maintenance are fundamentally linked within this system, with perturbations in membrane traffic quickly leading to changes in organelle structure and identity. Dissection of the molecular basis of these properties in yeast and mammalian cells has revealed a crucial role for the cytoplasmic protein complex ARF1/COPI, which undergoes regulated assembly and disassembly with membranes. ARF1/COPI appears to be involved in the formation and maintenance of the Golgi complex, which is the receiving and delivery station for all secretory traffic. ARF1-GTP, through assembly of COPI to membranes and, possibly, through activation of PLD, is likely to promote the formation and maturation of pre-Golgi intermediates into Golgi elements, whereas ARF-GDP causes COPI dissociation and stimulates the formation of retrograde transport structures that recycle Golgi membrane back to the ER. These processes are appear to underlie the coupling of organelle biogenesis and membrane trafficking within cells, allowing the size and shape of secretory organelles to be altered in response to changing cellular needs. Future work needs to address how the activation and localization of ARF1/COPI to membranes as well as other related factors are temporally and spatially regulated, and by what mechanism they transform membrane shape and dynamics to facilitate protein transport and compartmental functioning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050247
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  • 14
    Electronic Resource
    Electronic Resource
    Technique of laparoscopic ultrasound examination of the liver and pancreas (1996)
    Springer
    Surgical endoscopy and other interventional techniques 10 (1996), S. 684-689 
    Details
    ISSN: 1432-2218
    Keywords: Laparoscopic ultrasound ; Intraoperative ultrasound ; Ultrasound technique ; Liver ; Pancreas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since the introduction of a recent laparoscopic ultrasound (LU), the value of this modality in examining the liver and pancreas has been reported. However, a precise scanning technique of LU has not previously been described. Based on our experience with intraoperative ultrasound during laparotomy, we have developed a technique for complete examination of the entire organs using a rigid LU probe. A 7.5-MHz rigid probe, 10 mm in diameter, was employed. The scanning was performed through three trocar ports: right subcostal, subxiphoid, and umbilical. For the liver, the subcostal scanning provided fundamental transverse views. The subxiphoid and umbilical scanning delineated the areas unable to be imaged by the subcostal scanning. For the pancreas, the subcostal and umbilical scanning demonstrated longitudinal and transverse views, respectively. The subxiphoid scanning enhanced examination of the pancreatic head. Three basic probe maneuvers (advancement-withdrawal, lateral movement, and rotation) and various scanning techniques (contact, probe-standoff, and compression scanning) should be utilized appropriately. With a rigid probe, complete LU examination of the liver and pancreas is possible using these techniques. We believe the present scanning method will help more surgeons learn LU.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00188531
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  • 15
    Electronic Resource
    Electronic Resource
    Production of recombinant herpes simplex virus protease in 10-L stirred vessels using a baculovirus–insect cell expression system (1997)
    Springer
    Journal of industrial microbiology and biotechnology 19 (1997), S. 87-91 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: baculovirus–insect cell expression vector system (BEVS); Sf-9; HSV protease; glutathione-S-transferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A gene expression system using recombinant Autographa californica nuclear polyhedrosis virus (baculovirus) and Sf-9 cells has been scaled up to the 10-L tank level and shown to be capable of producing herpes simplex virus (HSV) protease in serum-free media. High densities of Spodoptera frugiperda (Sf-9) cells were achieved by modifying two 10-L Biolafitte fermenters specifically for insect cell growth. The existing Rushton impellers were replaced by marine impellers to reduce shear and the aeration system was modified to allow external addition of air/O2 mixtures at low flow rates through either the sparge line or into the head space of the fermenter. To inoculate the tanks, Sf-9 cells were adapted to grow to high cell densities (6–10 × 106 cells ml−1) in shake flasks in serum-free media. With these procedures, cell densities of 5 × 106 cells ml−1 were routinely achieved in the 10-L tanks. These cells were readily infected with recombinant baculovirus expressing the 247-amino acid catalytic domain of the HSV-1 strain 17 protease UL26 gene as a glutathione-S-transferase (GST) fusion protein (GST-247). Three days after infection at a multiplicity of infection (MOI) of 3 pfu cell−1, the GST-247 fusion protein was purified from a cytoplasmic lysate by Glutathione Sepharose 4-B affinity chromatography with reproducible yields of 11–38 mg L−1 of recombinant protein and ≥ 90% purity. Maximum production of this protein was observed at a cell density of 5.0 × 106 cells ml−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900446
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  • 16
    Electronic Resource
    Electronic Resource
    Superconductive YBa2Cu3O7−x fibres from an extrudable dispersion of a particulate precursor (1995)
    Springer
    Journal of materials science 30 (1995), S. 3467-3470 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A particulate precursor of YBa2Cu3O7−x was dispersed in a concentrated acetic/formic acid solution of yttrium, barium and copper acetates to form an extensible, viscous mixture. This dispersion was stable, unlike one prepared from superconductive YBa2Cu3O7−x itself. Fibres extruded from the viscous dispersion were fired at 935 °C in the presence of oxygen. Although the fired fibres were not fully densified, they had a sharp Meissner transition temperature at 90 K and an apparent critical current density (J c) of 900 A cm−2 (1800 A cm−2 corrected for porosity) at 77 K. The superconducting fibre was sensitive to magnetic field, which is evidence of weak coupling between the superconducting grains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349896
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  • 17
    Electronic Resource
    Electronic Resource
    Ionic permeabilities induced by Bacillus thuringiensis in Sf9 cells (1995)
    Springer
    The journal of membrane biology 148 (1995), S. 57-63 
    Details
    ISSN: 1432-1424
    Keywords: Bacillus thuringiensis ; Insecticidal toxins ; Sf9 cells ; PBFI ; Monovalent cations ; Intracellular pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The effect of Bacillus thuringiensis insecticidal toxins on the monovalent cation content and intracellular pH (pH i ) of individual Sf9 cells of the lepidopteran species Spodoptera frugiperda (fall armyworm) was monitored with the fluorescent indicators potassium-binding benzofuran isophthalate (PBFI) and 2′,7′-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). The sequential removal of K+ and Na+ from the medium, in the presence of CryIC, a toxin which is highly active against Sf9 cells, caused sharp shifts in the fluorescence ratio of PBFI, demonstrating a rapid efflux of these ions. In Sf9 cells, pH i depends strongly on the activity of a K+/H+ exchanger. In the absence of toxin, removal of K+ from the external medium resulted in a reversible acidification of the cells. In the presence of CryIC, pH i equilibrated rapidly with that of the bathing solution. This effect was both time- and concentration-dependent. In contrast with CryIC, CryIIIA, a coleopteran-specific toxin, and CryIA(a), CryIA(b) and CryIA(c), toxins which are either inactive or poorly active against Sf9 cells, had no detectable effect on pH i . B. thuringiensis endotoxins thus appear to act specifically by increasing the permeability of the cytoplasmic membrane of susceptible cells to at least H+, K+ and Na+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234156
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  • 18
    Electronic Resource
    Electronic Resource
    Carbohydrate and calling: Depletion of muscle glycogen and the chorusing dynamics of the neotropical treefrog Hyla microcephala (1995)
    Springer
    Behavioral ecology and sociobiology 37 (1995), S. 125-135 
    Details
    ISSN: 1432-0762
    Keywords: Frog ; Energetics ; Chorusing ; Glycogen ; Female choice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chorusing males of the neotropical treefrog Hyla microcephala call in distinct bouts punctuated by periods of silence, a pattern known as unison bout singing. Schwartz (1991) previously tested and refuted the hypotheses that males periodically stop calling either because of a female preference for males that call cyclically, or because high ambient noise levels inhibit vocal activity. Males of H. microcephala are vocally responsive to the calls of other males, and during calling bouts their rate of note production can exceed 10,000 per hour. In natural choruses females preferentially pair with males that call at the higher rates. Because females can pair with males over many hours, males may stop calling periodically to save energy so they can continue to call for the entire period that females are available. We directly tested this energy conservation hypothesis by collecting samples of males early in the evening just after chorusing commenced and later when chorusing had ended for the night. Trunk muscles (internal and external oblique), which are responsible for the airflow associated with note production, were dissected, frozen, and their glycogen content measured. Data on calling behavior were obtained for late-evening samples. Individual calling behavior was not correlated with a male's final glycogen level. In addition, many males ended their calling before glycogen reserves were exhausted, indicating that factors other than energy can determine when males finally stop chorusing. However, the biochemical assays supported the energy conservation hypothesis. Unless chorusing was punctuated by pauses, most males would have been unable to sustain high rates of calling for an entire evening without exhausting glycogen reserves in their trunk muscles. Because the time females pair with males is probably unpredictable to males., the ability to call for long periods may improve a male's chances of mating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00164158
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  • 19
    Electronic Resource
    Electronic Resource
    Mast cell specific proteases in rat brain: changes in rats with experimental allergic encephalomyelitis (1997)
    Springer
    Journal of neural transmission 104 (1997), S. 399-417 
    Details
    ISSN: 1435-1463
    Keywords: Rat mast cell protease I ; rat mast cell protease II ; experimental allergic encephalomyelitis ; histaminergic neurons ; histamine H3 receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Mast cell populations were identified within brain parenchyma by their specific proteases, using antibodies for immunohistochemistry and ELISAs, and riboprobes were developed for in situ hybridisation. Connective tissue mast cells expressing rat mast cell protease I (RMCPI) mRNA and immunoreactivity were observed in thalamus and showed no degranulation at 3, 8 and 13 days after induction of experimental allergic encephalomyelitis (EAE). Mucosal-like mast cells were clearly demonstrated in control rats by measuring RMCPII and by visualising cells expressing RMCPII mRNA and immunoreactivity. At day 13, but not 3 and 8 post immunisation, the number of RMCPII-expressing cells markedly increased in the EAE-induced group, mainly within brainstem and spinal cord close to inflammed blood vessels. The markers of histaminergic neurons were marginally affected 13 days after immunisation and the increase of [3H] histamine synthesis elicited by the H3-receptor antagonist, thioperamide, was not modified in any region of the brain. It is concluded that the cerebral RMCPII-expressing mast cells could play a role during EAE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01277659
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  • 20
    Electronic Resource
    Electronic Resource
    Antipsychotics with inverse agonist activity at the dopamine D3 receptor (1996)
    Springer
    Journal of neural transmission 103 (1996), S. 1163-1175 
    Details
    ISSN: 1435-1463
    Keywords: [3H]thymidine incorporation ; negative antagonist ; partial agonist ; cyclic AMP accumulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In NG 108-15 cells expressing the recombinant human D3 receptor, dopamine agonists enhance [3H]thymidine incorporation and decrease cAMP accumulation. In these cells, but not in wild type cells, haloperidol, fluphenazine, and various other antipsychotics inhibited basal [3H]thymidine incorporation in a concentration-dependent manner. In contrast, other dopamine antagonists such as nafadotride or (+)AJ 76, two D3-preferring antagonists, were without effect. The concentration-response curve of haloperidol was shifted to the right in presence of nafadotride, with a potency compatible with its nanomolar apparent affinity as neutral antagonist. Pertussis toxin treatment abolished or markedly reduced the responses to haloperidol or fluphenazine. In contrast, no significant enhancement of cAMP accumulation could be observed, under the influence of haloperidol or eticlopride. These data indicate that some dopamine antagonists behave as inverse agonists, and thus appear to inhibit an agonist-independent activity of the D3 receptor on [3H]thymidine incorporation pathway, but not on the cAMP pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01271201
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