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  • Animals  (9)
  • Life and Medical Sciences  (8)
  • ASTROPHYSICS  (5)
  • carbamazepine  (4)
  • *Tropical Climate  (2)
  • 1
    Publication Date: 2002-08-24
    Description: Populations of the garter snake Thamnophis sirtalis have evolved geographically variable resistance to tetrodotoxin (TTX) in a coevolutionary arms race with their toxic prey, newts of the genus Taricha. Here, we identify a physiological mechanism, the expression of TTX-resistant sodium channels in skeletal muscle, responsible for adaptive diversification in whole-animal resistance. Both individual and population differences in the ability of skeletal muscle fibers to function in the presence of TTX correlate closely with whole-animal measures of TTX resistance. Demonstration of individual variation in an essential physiological function responsible for the adaptive differences among populations is a step toward linking the selective consequences of coevolutionary interactions to geographic and phylogenetic patterns of diversity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Geffeney, Shana -- Brodie, Edmund D Jr -- Ruben, Peter C -- Brodie, Edmund D 3rd -- New York, N.Y. -- Science. 2002 Aug 23;297(5585):1336-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Utah State University, Logan, UT 84322, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12193784" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials ; Adaptation, Physiological ; Animals ; *Biological Evolution ; Colubridae/*physiology ; Drug Resistance ; Linear Models ; Locomotion/drug effects ; Muscle Fibers, Skeletal/drug effects/physiology ; Muscle, Skeletal/drug effects/*physiology ; Neuromuscular Junction/drug effects/physiology ; Predatory Behavior ; *Salamandridae/metabolism ; Skin/chemistry ; Sodium Channels/*drug effects/physiology ; Tetrodotoxin/*toxicity ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2004-04-03
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Young, Kevin V -- Brodie, Edmund D Jr -- Brodie, Edmund D 3rd -- New York, N.Y. -- Science. 2004 Apr 2;304(5667):65.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Utah State University, Logan, UT 84322-5305, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/15001716" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Female ; Lizards/*anatomy & histology ; Male ; *Predatory Behavior ; *Selection, Genetic ; *Songbirds
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 35 (1988), S. 241-247 
    ISSN: 1432-1041
    Keywords: carbamazepine ; porphyria ; epilepsy ; haem biosynthesis ; enzyme induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The anticonvulsant drug carbamazepine has been reported to produce a condition clinically and biochemically similar to acute intermittent porphyria (AIP). We have determined the effect of chronic carbamazepine treatment on the activities of the enzymes of haem biosynthesis in circulating blood cells and on the urinary excretion of porphyrins and their precursors in 53 epileptic patients receiving monotherapy and in 42 age- and sex-matched controls. In the patients the mean activity of leucocyte 5-aminolaevulinic acid (ALA) synthase, the rate-limiting enzyme of the pathway, was 218% of control values (p〈0.001) and ALA-dehydratase activity was reduced by 37% (p〈0.001). Circulating carbamazepine concentrations correlated negatively with ALA dehydratase (r s=−0.45;p〈0.01). Porphobilinogen deaminase and uroporphyrinogen decarboxylase appeared unaffected by carbamazepine treatment. Significant quantitative increases in the urinary excretion of porphobilinogen and total porphyrins (bothp〈0.05) accompanied the changes in enzyme activity. Similar dose-dependent effects on ALA synthase and ALA dehydratase were shown to occur in rats treated for 5 days with 3 different doses of carbamazepine. These findings further support the porphyrinogenicity of carbamazepine, but the pattern of enzyme alteration differs from that found in AIP.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 31 (1986), S. 195-199 
    ISSN: 1432-1041
    Keywords: carbamazepine ; epilepsy ; anticonvulants ; psychomotor function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of an additional dose of 400 mg carbamazepine (CBZ) on a series of simple psychomotor tests was investigated in 8 patients with epilepsy receiving chronic CBZ monotherapy in a balanced randomised double-blind placebo controlled cross-over study. Psychomotor testing and blood sampling for total and free CBZ and CBZ 10,11 epoxide (CBZ-E) concentrations were performed at 10, 12, 14, 16 and 18 h after the extra dose which was administered at 23.00 h on the previous evening. The CBZ increment produced significant impairment of (i) choice reaction recognition time from 10–16 h after the dose (ii) total choice reaction time at 12 h (iii) card sorting at 12 h (iv) sedation scoring at 12 h. No significant effect on critical flicker fusion threshold, finger tapping or simple memory testing was noted. No patient reported increased side-effects in the placebo phase while 5 noted new symptoms likely to be attributable to the additional CBZ. Areas under the concentration-time curves from 10–18 h were higher following CBZ than placebo for total and free CBZ and CBZ-E concentrations. This study has demonstrated decrements in performance of a series of simple psychomotor tests in epileptic patients receiving a supplemental CBZ dose. Patients with epilepsy who require high CBZ concentrations for optimal control of seizures may be at risk of concurrent impairment of psychomotor function. Simple objective measures of performance may help in assessing the benefit-risk ratio.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 453-456 
    ISSN: 1432-1041
    Keywords: carbamazepine ; thyroid hormones ; antipyrine ; enzyme induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of short-term hepatic enzyme induction with carbamazepine (CBZ) on circulating thyroid hormone concentrations was studied in 10 healthy male subjects. CBZ 400 mg per day was given for 21 days in 6 subjects and for 14 days in a further 4. In the former group the effect of therapy on the pituitary/thyroid axis was also assessed by measuring thyroid stimulating hormone (TSH) response to thyrotrophin-releasing hormone. CBZ therapy resulted in induction of hepatic monooxygenase activity, evidenced by a fall in antipyrine half-life (11.1±0.7 to 7.6±0.7 h; p〈0.001), and a rise in antipyrine clearance (0.72±0.06 to 0.98±0.1 ml min−1 kg−1; p〈0.001). A significant fall in total serum thyroxine (T4) (81.9±2.9 to 75.1±2.9 nmol l−1), and triiodothyronine (T3); (1.59±0.07 to 1.37±0.05 nmol l−1) and free T4 (16.03±0.82 to 14.2±0.8 pmol l−1) was seen after CBZ therapy. (all p〈0.05). No significant change in reverse T3 or thyroid binding globulin occurred. In the 6 subjects studied for 21 days, maximal changes were found following 14 days' treatment. Basal and stimulated TSH remained unaltered. These effects on circulating thyroid hormone concentrations are likely to be secondary to hepatic enzyme induction leading to accelerated nondeiodinative hepatic hormone disposal. The reason for the failure of pituitary TSH secretion to rise in response to the fall in circulating T4 and T3 is unclear but may have implications for chronic treatment with CBZ in epileptic patients.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 30 (1986), S. 37-42 
    ISSN: 1432-1041
    Keywords: carbamazepine ; psychomotor function ; anticonvulsants ; epilepsy ; healthy subjects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of a single dose of carbamazepine (CBZ), 10 mg kg−1, on a battery of simple psychomotor tests was investigated in 12 healthy subjects (6 male, 6 female) in a balanced randomised double blind placebo controlled cross-over study. Psychomotor testing and blood sampling for total and free plasma CBZ, and CBZ 10, 11 epoxide concentration were performed at 10, 12, 14, 16, 18 and 34 h after oral dosing (23.00 h the previous evening). CBZ impaired i) critical flicker fusion threshold frequency at all time points up to 18 h (p〈0.005); ii) total choice reaction time at 10 h (p〈0.005) and 18 h (p〈0.008); iii) card sorting at 14 h (p〈0.001). No significant effect on finger tapping was noted. Subjects adjudged themselves more sedated on CBZ as compared to placebo at 12, 14 and 16 h (p〈0.008). Plasma total and free CBZ concentrations (mean ± SD) peaked at 10 h (8.8±0.2 mg l−1) and 16 h (1.88±0.3 mg l−1) after dosing respectively. CBZ 10, 11 epoxide values were all less than 10% of total CBZ concentrations and, therefore, were unlikely to contribute to the pharmacodynamic effect. Total choice reaction time was significantly more impaired in females (p〈0.05) but no sex difference occurred with the other tests or CBZ concentrations at any time point. No significant correlations were found between individual total or free CBZ concentrations and corresponding test performances at each time point. This study has demonstrated impairment of psychomotor function following CBZ in healthy subjects using a series of simply performed tests. This approach can now be applied to patients with epilepsy receiving long-term treatment with CBZ and other anticonvulsants.
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  • 7
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 130 (1987), S. 191-198 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The role of Na-K ATPase in the determination of resting membrane potential (Em) as a function of extracellular K ion concentration was investigated in cultured rat myotubes. The Em of control myotubes at 37°C varied as a function of (K+)0 with a slope of about 58-60 mV per ten-fold change in (K+)0. Inhibition of the Na-K pump with ouabain or by reduced temperature revealed that this relation consists of two components. One, between (K+)0 of 10 and 100 mM, remains unchanged by alterations in enzyme activity; The second, between (K+)0 of 1 and 10 mM, is related to the amount of Na-K pump activity, the slope decreasing as pump activity decreases. Indeed, with complete inhibition of the Na-K pump, Em does not change over the range of (K+)0 1 to 10 mM. Measurements of 86Rb efflux and input resistance of individual myotubes showed that membrane permeability does not change as (K+)0 increases from 1 to 10 mM but increases as (K+)0 increases further. Monensin, which increases Na ion permeability, increases Em at values of external K+ below 10 mM, and is without effect at higher values of K+ concentration. The effect of monensin is blocked by ouabain. Tetrodotoxin, which blocks voltage-dependent Na+ channels, decreases Em at low (2-10 mM) K+. We conclude that changes in Em as a function of extracellular K+ concentration in the physiological range are not adequately explained by the diffusion potential hypothesis of Em, and that other theories (electrogenic pump, surface-absorption) must be considered.
    Additional Material: 7 Ill.
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  • 9
    ISSN: 0148-7280
    Keywords: rat oocytes ; meiosis ; steriodogenesis ; inhibitors ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study examined the possible role of steriods in meiotic maturation of preovulatory oocytes. Follicles were isolated from PMSG-treated immature rats and incubated with or withour LH in the presence of one of four inhibitors of steroidogenesis. The inhibitors employed had different sites of attack in the steriodogenic pathway and were aminoglutethimide, cyanoketone, SU 10603 (17β-hydroxylase inhibitor), and 4-OH-androstenedione (aromatase inhibitor). As predicted, the inhibitors drastically altered the pattern of steroid production. None of the inhibitors, however, changed the proportion of oocytes resuming or completing meiosis in response to LH, and there was also no effect of the inhibitors on the oocytes in the absence of LH. It was concluded that steriods are not required for preovulatory nuclear maturation of oocytes in the rat.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 144 (1990), S. 492-497 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have examined effects of nerve growth factor (NGF) and fibroblast growth factor (FGF) on the density of tetrodotoxin (TTX)- sensitive Na-channels in cultured rat skeletal muscle. Measurements were made of specific binding of [3H] saxitoxin (STX) and the frequency and rate of rise of spontaneously occurring action potentials, the Physiological expression of Na-channel density. Cells were transferred to various growth conditions at 6 days in vitro, and measurements were made beginning 24 hr later. Both growth factors (GF) caused dose-related in creases in Na-channels compared with myotubes maintained in normal, serum-supplemented growth medium. Maximum effects occurred with a concentration of NGF of 50 ng/ml and FGF of 15 ng/ml. Scatchard analysis of specific STX binding showed an increase in Bmax with no significant change in Kd. Similar increases occurred on rate of rise and frequency spontaneous action potentials. Treatment of cultures with cycloheximide or actinomycin D, inhibitors of protein and RNA synthesis, completely prevented the increase in STX-binding induced by GF treatment, The results indicate that NGF and FGF have important effects on regulation of excitable cell gene products after differentiation.
    Additional Material: 7 Ill.
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