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  • 1
    ISSN: 1573-904X
    Keywords: dissolution ; tablet stability ; solid state reaction ; croscarmellose sodium ; disintegrant ; infrared spectroscopy ; CP/MAS NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To investigate the cause for decrease in delavirdine mesylate 200 mg tablet dissolution upon exposure to high humidity. Methods. Dissolution testing was performed using the USP 2 (paddle) apparatus. Water in tablets was measured by Karl Fischer titration. 13C CP/MAS NMR was used to identify and quantify delavirdine form changes in tablets. FT-IR spectroscopy was used to monitor delavirdine form change in tablets and component mixes, and to investigate a solid state reaction with the disintegrant. Results. Dissolution extent of delavirdine mesylate 200 mg tablets was substantially decreased after exposure to high humidity. This effect is related to the amount of water present in the tablet matrix. 13C CP/ MAS NMR detected about 30% conversion from the mesylate salt of delavirdine to its free base form in the tablet matrix. FT-IR spectroscopy demonstrated that a solid state reaction occurs between the freed methanesulfonic acid and the carboxyl sites on the croscarmellose sodium disintegrant. Conclusions. Water is thought to act as both a reaction medium and a plasticizer for croscarmellose sodium, facilitating protonation of the carboxyl sites on the disintegrant. This reaction has the potential to occur for any acid salt of a free base. The limiting solubility of delavirdine free base formed in the tablets accounts for much of the decrease in the extent of dissolution. A change in inter-particle bonding can explain the reduction in tablet deaggregation during dissolution.
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  • 2
    ISSN: 1573-4919
    Keywords: streptozotocin ; blood vessels ; glycolysis ; glucose oxidation ; palmitate oxidation ; insulin-deficient diabetes ; sodium-potassium ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Several investigators have reported that carbohydrate metabolism is suppressed in blood vessels from diabetic (Db) rats. However, it is not known if metabolites from the reciprocal increase in oxidation of long-chain fatty acids that accompanies insulin-deficiency exacerbates the suppression of this pathway in the Db blood vessels. Such inhibition may have particularly deleterious consequences in vascular smooth muscle since aerobic glycolysis is believed to preferentially fuel the sarcolemmal Na/K ATPase in this tissue. Therefore, this study evaluated the effect of physiological (0.4 mM) and elevated (1.2 mM) concentrations of the long-chain fatty acid palmitate on both carbohydrate utilization and Na/K-ATPase activity in aorta from insulin-deficient Db rat. Thoracic aorta were removed from 10 week Db (streptozotocin 60 mg/Kg , i.v.) or control (C) rats and intima-media aortic preparations were incubated in the absence or presence of palmitate. Glycolysis (μM/g dry wt/h) and glucose oxidation (μM/g dry wt/h) were quantified using 3H-glucose and 14C-glucose, respectively. Na/K-ATPase activity was estimated by the measurement of 86rubidium uptake in the absence and presence of 2 mM ouabain. In the absence of exogenous palmitate, glycolysis (p 〈 0.05), glucose oxidation (p 〈 0.01) and the estimated ATP production from exogenous glucose were decreased in aorta from Db rat. However, despite this diminished rate of glycolysis, Na/K ATPase activity was similar in Db and C aorta. Palmitate (0.4 mM) inhibited Na/K ATPase activity and glucose oxidation to a similar extent in both Db and C but had no effect on glycolysis in either group. Elevation of palmitate to 1.2 mM had no additional inhibitory effect on glucose oxidation, Na/K ATPase activity or glycolysis in either the Db or C aorta. The metabolism of exogenous palmitate restored the ATP production in Db to control values. These data demonstrate that, despite the diminished glycolysis and glucose oxidation demonstrated in the Db tissue, Na/K ATPase activity was comparable in the C and Db aorta, in the absence or presence of exogenous long-chain fatty acid. Therefore, the accelerated oxidation of palmitate in diabetic vascular smooth muscle had no additional inhibitory effect on glycolysis or Na/K ATPase activity. These data suggest that Na/K ATPase activity in vascular smooth muscle is not impaired by the altered pattern of substrate utilization that occurs in insulin-deficient Db rats.
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  • 3
    ISSN: 1572-9699
    Keywords: Arachidonic acid ; isolation ; Mortierella ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Malt extract agar and an incubation temperature of 5 °C were used to selectively isolate representatives of the genus Mortierella from soil. Fungi in a soil sample from mountain grassland able to grow under these conditions, amounted to a total of 2640 colony forming units per gram soil. Circa 94% of the total fungal isolates represented Mortierella subgenus Mortierella. The rest of the colony-forming units consisted of Mucor isolates (6.0%) and higher fungi (1.5%). All the Mortierella isolates produced arachidonic acid.
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  • 4
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 5
    ISSN: 1573-5176
    Keywords: Alginate ; pilot plant process ; extraction ; Macrocystispyrifera ; filtration ; centrifugation ; flocculation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of temperature (70, 80, 90 °C) and time (1–9 h) during the alkaline extraction step on alginate yield and quality were studied. The alginate yield increased with time and maximum yield was obtained after 3.5 h treatment, ranging from19.4% at 70 °C to 21.9% at 90 °C. The viscosity of the alginate produced was inversely correlated with the temperature and time. At70 °C the slope of the curve was almost zero(753 to 923 mPa s); at 90 °C the viscosity loss was 154 mPa s per hour during the first two hours, reducing from 523 to 86 mPa s after 5 h; 80 °C yielded values between those for 70 °C and90 °C. The best conditions for alkaline extraction were using pH 10 at 80 °C for two hours. The curves obtained gave useful information for controlling the viscosity of the alginate during production. It was found that viscosity of the paste formed during alkaline extraction (`process viscosity') was the best parameter to determine there action rate during extraction. Alginate yield increased during filtration time from 17.6% to 23.7%after 55 min at 70 °C. In this step the viscosity of the alginate obtained remained almost constant (522–610 mPa s), indicating no degradation of the products during filtration. The best dilution to filter the alginate extract was obtained at 45 mPa s. Diatomaceous earth (Celite) and expanded lava(Perlite) were tested as filter aids. Expanded lava was the best filter aid, using 1 kg per kilogram of alginate produced. Three methods were studied to separate the alkaline-insoluble residues after extraction: filtration, centrifugation, flocculation, and combinations of them. The best system found was filtration with flocculant in a rotary vacuum filter, with a knife advance of 0.1 mm every 3.5 seconds and drum rotation of 2 rpm, yielding an average filtration flow rate of 10.5 L min-1.
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  • 6
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic spectrum of germylidene (H2C(Double Bond)Ge), the simplest unsaturated germylene, has been observed for the first time. Jet-cooled H2CGe and D2CGe were produced by an electric discharge through tetramethylgermane diluted in argon at the exit of a supersonic expansion. High-resolution spectra of H2C74Ge and D2C74Ge, obtained from (CH3)4〈sup ARRANGE="STAGGER"〉74Ge prepared from isotopically enriched 74Ge metal, have been rotationally analyzed to yield the following r0 structures: r0″(CGe)=1.7908(2) Å, r0″(CH)=1.1022(5) Å, θ0″(HCH)=115.05(5)°, r0′(CGe)=1.914(4) Å, r0′(CH)=1.082(9) Å, and θ0′(HCH)=139.3(11)°. The 367–354 nm B˜1B2–X˜ 1A1 band system consists of prominent perpendicular bands involving the CGe stretching (ν3) and CH2 scissors (ν2) vibrations and a weaker series of vibronically induced parallel bands involving the CH2 rocking mode (ν6). Vibronic bands involving Δv=2 changes in ν6(b2) and ν4(b1) have also been assigned. The fluorescence decays of single rotational levels of the 000 band of H2C74Ge exhibit molecular quantum beats for about 70% of the levels surveyed. Density of states arguments reveal that most of the beats originate from interactions with high rovibronic levels of the ground state. In one case, hyperfine splittings in the Fourier transform of the beat pattern indicate an accidental coincidence with an excited triplet state level. The less frequent occurrence of quantum beats in germylidene compared to silylidene, where they are almost universal, can be attributed to the smaller density of ground state levels at the zero-point energy of the S2 state in the former. © 1999 American Institute of Physics.
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  • 7
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Helgoland marine research 10 (1964), S. 313-327 
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary 1. During the exceptionally cold winter of 1962/63 the south east coasts of Great Britain suffered the coldest conditions, but the coasts of Hampshire and Dorset, the Bristol Channel and parts of North Wales the greatest negative anomalies. 2. Northern forms were not generally seriously affected, but some Celtic and southern forms suffered very high mortality in the intertidal zone, particularly in embayed situations in the areas mentioned above. 3. Southern forms limited to exposed western promontories did not suffer much damage; marine algae were also little affected. 4. Death was caused, not only as a direct result of exposure of the tissues to extreme cold, but also from the general lowering of the animals' activity; for example, failure to remove silt by ciliary action, to cling to rock surface, and to burrow, led to many deaths. 5. Even where high mortality was experienced, a few, perhaps more resistant, individuals of the species generally survived in favourable habitats, so that distribution limits were little affected. Adaptive behaviour played an important part in the survival of many littoral forms.
    Notes: Kurzfassung Während des ungewöhnlich kalten Winters 1962/63 herrschten die niedrigsten Temperaturen an der Südostküste Großbritanniens. Die größten negativen Anomalien dagegen wurden an den Küsten von Hampshire und Dorset, im Bristol-Kanal und in Teilen von Nord-Wales festgestellt. Die nördlichen Formen wurden im allgemeinen nicht ernstlich beeinträchtigt, aber einige keltische und südliche Formen erlitten sehr hohe Verluste im Bereich der Gezeitenzone, insbesondere in mehr oder minder abgeschlossenen Buchten im Gebiet der oben erwähnten Lokalitäten. Bei den südlichen Formen der exponierten Küsten der westlichen Vorgebirge war die Sterblichkeit relativ gering; marine Algen wurden ebenfalls nur wenig geschädigt. Der Tod trat nicht nur als direkte Folge der Kälteeinwirkung auf die Gewebe ein, sondern wurde auch durch die zu weit gehende Herabsetzung der Aktivität (etwa unzureichende Zilienaktivität zur Entfernung sedimentierender Schlammpartikel, mangelnde Anhaftungsfähigkeit an die Felsoberfläche oder ungenügendes Eingrabungsvermögen) verursacht. Selbst in Situationen, in denen hohe Sterblichkeitsraten auftraten, überlebten im allgemeinen einige wenige (vielleicht resistentere) Individuen in günstigen Habitaten, so daß die Verbreitungsgrenzen nur geringfügig beeinflußt wurden. Bei vielen Litoralformen spielte zudem ein adaptives Verhalten eine wichtige Rolle für das erfolgreiche Überstehen der Kälteperiode.
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  • 9
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the replacement of dmso in FePc(dmso)2 by piperidine and 11 substituted pyridines, to form FePc(base)2 species, have been studied by stopped-flow techniques. For the first step a linear free energy relationship (LFER) exists between the rate constant for fission of base from FePc(base)(dmso) and the gas phase proton affinity of the base, from bases with low proton affinity (CO) to high proton affinity (CN−). The rate constant for dmso fission from FePc(dmso)2 was estimated to be ca. 420,000 s−1, and this fission process largely governs the rate of the first step for neutral bases. The slow first step for the reaction with cyanide ion as base can be explained when the energy needed to de-pair cyanide and potassium ions is taken into account. In the second step the formation rate constants of FePc(base)2 species cover one order of magnitude for neutral bases, and the base dissociation rate constants cover two orders of magnitude, with a good LFER between these constants and the pKBH of the leaving group. There is also a good LFER between the equilibrium constant for bis-base complex formation and these same dissociation rate constants.
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  • 10
    ISSN: 1432-2307
    Keywords: Key words Kidney ; Solitary cyst ; Transitional cell carcinoma ; Fine-needle aspiration biopsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The differentiation between benign and malignant cystic lesions of the kidney is a diagnostic challenge. Medical imaging aids in this task, but many cystic renal lesions require further work-up, frequently by computed tomography-guided fine needle aspiration. We report on the pathological findings in a case of moderately differentiated papillary transitional carcinoma, which arose in a pre-existing pyelocaliceal cyst in a 53-year-old man. In the case of this lesion, the distinction between a benign and a malignant renal cyst is blurred. To our knowledge, this is the third such occurrence to be reported and the first to be diagnosed by fine needle aspiration biopsy.
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