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  • 1
    ISSN: 1432-1041
    Keywords: alfuzosin ; prazosin ; alpha1-adrenoceptor antagonist ; noradrenaline ; pharmacokinetics ; pharmacodynamics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In an open dose ranging study with random inclusion of placebo, alfuzosin (α1-adrenoceptor antagonist) 1, 2.5 and 5 mg was administered to 6 healthy volunteers, 3 of the volunteers received 10 mg alfuzosin. Supine systolic blood (SBP) pressure was not reduced by alfuzosin although significant increases occurred in supine heart rate (HR) after 2.5 and 5 mg. In the standing position, SBP was reduced at 2 and 4 h with 5 mg alfuzosin; significant increases in HR occurred following 1, 2.5 and 5 mg at 2, 4, 6 and 8 h after administration. Exercise SBP was not reduced; diastolic blood pressure was significantly reduced at 4 and 6 h with 5 mg alfuzosin. More marked effects were seen in the 3 subjects who received 10 mg alfuzosin. After 1 and 5 mg, tmax ranged from 1–2 h; Cmax (4.1 to 20.8 ng · ml−1; AUC (0–24) 20 to 132 ng · ml−1 · h (1 and 5 mg respectively) increased progressively with dose indicating dose dependent kinetics; no significant changes occurred in the visual analogue scale for sedation. A comparison of alfuzosin 5 mg, prazosin 1 mg and placebo each administered for 4 days, indicated that alfuzosin did not significantly reduce standing SBP on either Day 1 or Day 4; prazosin reduced SBP at 2 and 4 h on Day 1 and 6 h on Day 4 compared to placebo. Standing HR was increased by alfuzosin at 2 h on Day 1 and Day 4; increases occurred with prazosin at 2, 4, 6 and 8 h on Day 1 and 6 h on Day 4. Supine plasma noradrenaline increased with alfuzosin and prazosin at 2 and 4 h on Days 1 and 4; the increases were not significantly different. The plasma elimination half-life (t1/2) for alfuzosin was 3.4 h and 3.1 h after acute and chronic administration; (t1/2) for prazosin was 2.6 and 2.9 h. In conclusion alfuzosin causes small reductions in systolic blood pressure, accompanied by a dose dependent increase in heart rate in the supine and standing position and following exercise.
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  • 2
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Potential exposure to pesticide residues resulting from burning wood treated with phenoxy and pyridine herbicides was assessed. Wood samples from trees treated with 2,4-D [2,4-dichlorophenoxy acetic acid], dicamba [3,6-dichloro-o-anisic acid], dichlorprop [2-(2,4-dichlorphenoxy) propionic acid], picloram [4-amino-3,5,6-trichloropicolinic acid], and triclopyr (3,5,6-trichloro-2-pyri dinyl)oxy acetic acid contained variable amounts of parent compound residues at 4, 8, and 12 months after application. At the time of the latter sampling, residues of 2,4-D, dicamba, and picloram were 〈2.1 mg/kg on a fresh weight basis. Mean residue concentrations of triclopyr and dichlorprop were somewhat higher at 3.5 and 13.0 mg/kg, respectively. In a laboratory experiment, samples with known amounts of herbicide residue were subjected to either slow or rapidly burning conditions in a tube furnace. During slow combustion, relatively stable compounds such as 2,4-D, dicamba, and dichlorprop were released in significant amounts. Rapid combustion greatly enhanced decomposition of 2,4-D, dicamba, dichlorprop, picloram, and triclopyr. A well-developed fire in a wood stove or fireplace, with active flaming combustion, where temperatures commonly reach 800–l,000°C, should result in greater than 95% thermal decomposition of the herbicides examined in this study. Burning of herbicide-treated wood under smoldering conditions could result in very low levels of herbicide residue in ambient indoor air. However, the exposure levels are less than 0.3% of the threshold limit value for 2,4-D and triclopyr. The exposure is also more than 3 orders of magnitude lower than the established acceptable daily intakes for these products.
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  • 3
    ISSN: 1420-908X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Exposure of the urinary bladder of rats to chemical irritants such as turpentine produces a long lasting inflammatory response. Chemosensitive primary afferent fibres supplying the bladder are excited by the irritants. Dorsal horn cells in L6, S1 are also excited, and show slowly developing and persistent increases in ongoing activity, responses to electrical stimulation of vesical afferents and distension of the bladder. These changes may provide an explanation for the sensory and reflex disturbances that occur in cystitis in man.
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  • 4
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The oxygen and carbon dioxide transporting properties of the haemolymph from an amphibious Australian crab,Holthuisana transversa were investigated. Within the temperature range 15 to 35°C increasing temperature markedly decreased oxygen affinity (ΔH=−54 kJ·mol−1). The Bohr effect was small at all temperatures with a mean value of −0.13. Over the temperature range 15–35°C there was a significant increase in the cooperativity of oxygen binding. Changing the concentration of Ca,l-lactate or haemocyanin in the haemolymph could elicit no significant change in either O2 affinity or cooperativity of O2 binding. There was no evidence in support of a specific effect of CO2 on oxygen affinity of either non-dialysed or dialysed haemolymph. The amount of CO2 that could be carried byH. transversa haemolymph was significantly reduced by increased temperature (approx. 14 to 12.5 mmol·l−1 CO2). Comparisons of oxygenated and deoxygenated haemolymph at a fixed pH were unable to demonstrate the presence of a significant Haldane effect. Combining data from oxygenated and deoxygenated haemolymph the buffer value was calculated to be in the range −6.2 to −8.5 mmol·l−1 HCO 3 − ·pH unit−1. The insensitivity ofH. transversa haemocyanin function to all modulating influences except temperature is discussed with respect to the ecology of this crab.
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  • 5
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Wild populations of white suckers (Catostomus commersoni) were exposed to a fluctuating ambient pH regime (pH 7 to 4 to 7 to 4) in natural soft water. Blood and muscle ionic composition together with the net flux rate of acid-base equivalents, other ion transfers as well as unidirectional Na+ and Cl− exchanges were measured simultaneously in intact fish. Exposure to a shift in water pH from 7 to 4 for 12 h resulted in a marked net influx of both H+ (or loss of base) and SO 4 2− concomitant with net losses of other major body ions (Na+, Cl−, K+, Ca2+, Mg2+) as well as inhibition of gill NaCl influx and stimulation of gill diffusional efflux, depressed plasma ion levels (Na+, Cl−, Ca2+) and epaxial white muscle intracellular ion loss (K+, Mg2+). These responses slowly reversed when the water pH was elevated back to pH 7 for 12 h. Complete recovery was not achieved for some variables, however, even by 48 h. The responses upon re-exposure to water pH 4 for 12 h paralleled those seen during the initial acid exposure period, indicating that the introduction of a short period of neutral pH between two periods of acid exposure, was not ameliorative. Exposure to a fluctuating ambient pH regime, therefore, seemed to be more detrimental to the fish than continued, gradual or prior acid exposure. A regression analysis was performed on the ion transfer rates measured simultaneously in individual fish over the fluctuating pH regime. The results showed that exchange diffusion appears to be an important mechanism of NaCl transfer in white suckers and that the net flux rate of acid/base equivalents via the gill is closely correlated with the difference between all major cation (Na+, K+, Ca2+, Mg2+) and anion (Cl−, SO 4 2− ) net transfer rates.
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  • 6
    ISSN: 1573-7241
    Keywords: hypertension ; drug therapy ; economic factors ; drug costs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Socioeconomic factors are important in the selection of drug therapy for hypertension in New Orleans. With a proponderance of blacks, and an economic recession in the city, the availability of a large variety of effective and relatively safe hypertensive medications does not in itself solve the problem of providing a lifetime of antihypertensive medication. We must know our patients well and take into consideration income, age, home environment, and family situation. Only then can drug therapy that is appropriate to this complex milieu be prescribed.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 161 (1987), S. 335-346 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an effort to understand the cellular basis of entrainment of circadian oscillators we have studied the role of membrane potential changes in the neurons which comprise the ocular circadian pacemaker ofBulla gouldiana in mediating phase shifts of the ocular circadian rhythm. We report that: 1. Intracellular recording was used to measure directly the effects of the phase shifting agents light, serotonin, and 8-bromo-cAMP on the membrane potential of the basal retinal neurons. We found that light pulses evoke a transient depolarization followed by a smaller sustained depolarization. Application of serotonin produced a biphasic response; a transient depolarization followed by a sustained hyperpolarization. Application of a membrane permeable analog of the intracellular second messenger cAMP, 8-bromo-cAMP, elicited sustained hyperpolarization, and occasionally a weak phasic depolarization. 2. Changing the membrane potential of the basal retinal neurons directly and selectively with intracellularly injected current phase shifts the ocular circadian rhythm. Both depolarizing and hyperpolarizing current can shift the phase of the circadian oscillator. Depolarizing current mimics the phase shifting action of light, while hyperpolarizing current produces phase shifts which are transposed approximately 180° in circadian time to depolarization. 3. Altering BRN membrane potential with ionic treatments, depolarizing with elevated K+ seawater or hyperpolarizing with lowered Na+ seawater, produces phase shifts similar to current injection. 4. The light-induced depolarization of the basal retinal neurons is necessary for phase shifts by light. Suppressing the light-induced depolarization with injected current inhibits light-induced phase shifts. 5. The ability of membrane potential changes to shift oscillator phase is dependent on extracellular calcium. Reducing extracellular free Ca++ from 10 mM to 1.3×10−7 M inhibits light-induced phase shifts without blocking the photic response of the BRNs. The results indicate that changes in the membrane potential of the pacemaker neurons play a critical role in phase shifting the circadian rhythm, and imply that a voltage-dependent and calcium-dependent process, possibly Ca++ influx, shifts oscillator phase in response to light.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 161 (1987), S. 347-354 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We have used intracellular recording to directly measure the effects of three experimental agents, light, elevated potassium seawater, and lowered sodium seawater on the membrane potential of the putative circadian pacemaker neurons of theBulla eye. These agents were subsequently tested for effects on the free running period of the circadian pacemaker. We report that: 1. When applied to the eye, light and elevated potassium seawater depolarized the putative pacemaker neurons, while lowered sodium seawater hyperpolarized them. The membrane potential changes induced by these agents are sustained for at least one hour, suggesting that they produce persistent changes in the average membrane potential of the putative pacemaker neurons. 2. The amplitude of the membrane potential response to the depolarizing agents varies with the phase of the circadian cycle. Depolarizations induced by light and elevated potassium seawater are twice as large during the subjective night than they are during the subjective day. No significant difference was found in the response to lowered sodium seawater at different phases. 3. Continuous application of each of these agents caused a lengthening of the free running period of theBulla eye. Constant light increased the period by 0.9 h, while the other depolarizing treatment (elevated potassium seawater) increased the free running period by 0.6 h. Both treatments increased the mean peak impulse frequency of treated eyes. The hyperpolarizing treatment also increased the period of the ocular pacemaker (+0.8 h), but had little effect on peak impulse frequency. 4. Simultaneous chronic application of a depolarizing period lengthening treatment (constant light) and a hyperpolarizing period lengthening treatment (lowered sodium seawater) resulted in cancellation of their effects on freerunning period. 5. In conclusion, we find that continuous application of agents which change the membrane potential of the putative circadian pacemaker neurons lengthens the free running period of theBulla ocular circadian pacemaker. We have previously reported that transient changes in membrane potential shift the phase of theBulla ocular rhythm. Thus membrane potential can influence two fundamental properties of theBulla circadian oscillator suggesting that it is an important element of the circadian oscillator mechanism.
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  • 9
    ISSN: 1432-1238
    Keywords: Tracheopathia osteochondroplastica ; Tracheal stenosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Tracheopathia osteochondroplastica (TPO) is a rare, but increasingly recognised condition in which there is accumulation of calcium phosphate with benign submucous proliferation of cartilage and bone beneath the tracheal mucosa, often with squamous metaplasia of the mucosal columnar epithelium. This condition is usually asymptomatic, but may be slowly progressive, causing haemoptysis, dry cough and dyspnoea. We report a case of TPO in which there was rapid progression of tracheal stenosis such that the size of endotracheal tube that the upper airway would accept changed from 8.00 mm to 3.0 mm during a six-week period. This extreme reduction in airway calibre had not been detected on spirometry nine days prior to his final admission. This is the first report of such rapid progression of tracheal stenosis associated with TPO.
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  • 10
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of a chest wall mesenchymoma in a five month old infant is presented, and the role of CT and MR are emphasized. There have been no prior reports of the CT or MR findings in this entity.
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