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  • 1985-1989  (1,535)
  • 1970-1974  (764)
  • 1960-1964
  • 1945-1949
  • Physical Chemistry  (916)
  • Electron microscopy  (734)
  • pharmacokinetics
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  • 101
    Electronic Resource
    Electronic Resource
    Single dose and steady-state pharmacokinetics of 4 mg and 8 mg oral salbutamol controlled-release in patients with bronchial asthma (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 49-52 
    Details
    ISSN: 1432-1041
    Keywords: salbutamol ; asthma ; controlled-release formulation ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Fifteen patients with asthma were given salbutamol controlled-release (SCR) 4 mg or 8 mg twice daily for seven days, in a randomised double-blind cross-over design. Plasma salbutamol levels were measured after the first and fifteenth doses for a 12 h period following drug ingestion. At steady-state the geometric mean values for Cmax were 8.2 ng/ml for 4 mg, and 16.1 ng/ml for 8 mg. Median tmax values were 300 and 240 min respectively. The geometric mean AUC (0–12) were 4507 ng·min·ml−1 and 8980 ng·min/ml. Peak to trough fluctuation ratios were 0.577 and 0.572. There were no significant differences between 4 mg or 8 mg formulations, for any of the parameters measured, after appropriate corrections for dose. The concentration-time profiles at steady-state showed little fluctuation in plasma salbutamol levels over the twelve hour dosing interval. These results show that 4 mg and 8 mg formulations of SCR provide smooth plasma profiles at steady-state with a twice daily dosing regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609424
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  • 102
    Electronic Resource
    Electronic Resource
    First dose and steady-state pharmacokinetics of oxcarbazepine and its 10-hydroxy metabolite (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 69-74 
    Details
    ISSN: 1432-1041
    Keywords: oxcarbazepine ; pharmacokinetics ; drug metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of oxcarbazepine (a new anticonvulsant which is a congener of carbamazepine) and of its 10-hydroxy metabolite were studied at the outset of therapy in 8 adult epileptics comedicated with other anticonvulsants. The pharmacokinetic study was repeated under steady-state conditions after 3 months of drug intake in 6 of these subjects. The plasma elimination half-life of oxcarbazepine appeared to lie in the range 1.0–2.5 h, and that of its 10-hydroxy metabolite averaged 8.4 h. The apparent oral clearance of the parent drug (averaging 2.51·kg−1·h−1) was high enough to suggest substantial presystemic elimination. The oral clearance fell after 3 months of drug intake, but the half-lives of the drug and metabolite showed no statistically significant change over this time. Steady-state plasma levels of both drug and metabolite were linearly related to drug dose, metabolite levels averaging 9 times those of the parent substance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609428
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  • 103
    Electronic Resource
    Electronic Resource
    Haemodynamic and pharmacokinetic evaluation of alfuzosin in man. A dose ranging study and comparison with prazosin (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 53-58 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609425
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  • 104
    Electronic Resource
    Electronic Resource
    Metabolism and disposition of intravenously administered acetyl-L-carnitine in healthy volunteers (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 59-63 
    Details
    ISSN: 1432-1041
    Keywords: acetyl-L-carnitine ; renal clearance ; pharmacokinetics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of acetyl-L-carnitine hydrochloride were investigated in 6 healthy volunteers of both sexes after i.v. injection of 500 mg of the drug, expressed as inner salt. Plasma concentrations and urinary excretion of acetyl-L-carnitine (A), L-carnitine (B) and total acid soluble L-carnitine fraction were evaluated over a period lasting from 24 h before to 48 h after the administration. Plasma concentrations of A increased quickly after administration and then declined reaching base values within 12 h. Conversely, plasma concentrations of B rose more slowly, reaching a peak in 30–60 min, and then declined to base values within 24 h. Most of the injected dose of acetyl-L-carnitine was recovered in the urine during the first 24 h after administration as B and A. Mean renal clearance of both A and B during the first 12 h after injection was higher than the base values, suggesting the presence of a saturable tubular reabsorption process which may counterbalance major changes occurring in plasma concentrations of L-carnitine pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609426
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  • 105
    Electronic Resource
    Electronic Resource
    The pharmacokinetics of low-dose dexamethasone in congenital adrenal hyperplasia (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 75-77 
    Details
    ISSN: 1432-1041
    Keywords: dexamethasone ; congenital adrenal hyperplasia ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of dexamethasone, given at low dose, were studied in 13 patients with congenital adrenal hyperplasia (CAH) to ascertain whether kinetics differed in this inherited disorder of cortisol metabolism from those seen in healthy individuals. Changes in plasma dexamethasone concentration after intravenous bolus, measured using a simple novel radioimmunoassay, were well described by a two-compartment open model with first-order kinetics. Values for λ2: 0.206 h−1, t1/2: 3.53 h, Vc: 24.41 and f: 0.64 were similar to those previously reported for normal subjects. There were considerable interindividual differences in parameter values and Cmaxp.o. (range 22–67 nmol/l). As suppression of the hypothalamo-pituitary-adrenal axis correlates with plasma dexamethasone levels, this variability may partly explain the differing dose and dose schedule requirements necessary to achieve adequate therapeutic control in the clinical management of CAH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609429
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  • 106
    Electronic Resource
    Electronic Resource
    Zero-order absorption and linear disposition of oral colchicine in healthy volunteers (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 79-84 
    Details
    ISSN: 1432-1041
    Keywords: colchicine ; pharmacokinetics ; oral administration ; zero-order absorption ; systemic availability ; dose dependency ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of colchicine has been studied in nine healthy male volunteers after oral doses of 0.5, 1, and 1.5 mg as tablets. Plasma and urine samples were collected over 48 h and analysed for colchicine by radioimmunoassay. Individual colchicine concentration profiles in plasma and urine were well described by a two-compartment open model with zero-order input. Considering the absorption variables as specific to each experiment, the lag time (0–0.35 h) and duration (0.39–2.38 h) of absorption were found to be independent of dose, while the zero-order rate constant of absorption (k0) increased linearly with dose. Disposition variables were taken as common to the three experiments, except in six subjects in whom renal excretion varied significantly across experiments in a dose-independent manner. For seven subjects the terminal half-life was 19.4 h, the oral apparent volume of distribution at steady-state (Vss/f) was 691 l, and the oral systemic clearance (CL/f) was 33.1 l·h−1. In the two other subjects, the values were unreliable, but the estimated terminal half-life was greater than 48 h, Vss/f ranged from 1690 to 3480 l, and CL/f was in the range of the other subjects in 1 subject, and it was about 15l·h−1 in the other. In the latter subject, these estimates, together with the observation that plasma concentration reached a plateau at 2 to 5 h after ingestion, suggest enterohepatic cycling of colchicine. Overall, the disposition of colchicine was linear in the dose range 0.5–1.5 mg, with a long terminal half-life, and absorption obeyed zero-order kinetics, with k0 proportional to dose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609430
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  • 107
    Electronic Resource
    Electronic Resource
    Influence of hyperlipidic food on the kinetics of slow-release formulations of theophylline (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 85-90 
    Details
    ISSN: 1432-1041
    Keywords: theophylline ; sustained-release formulation ; bioavailability ; fatty food ; dumping effect ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A cross-over study of kinetics has been undertaken in 12 healthy adults volunteers using two sustained-release theophylline products that allow once a day dosing (Theo-Dur tablets and Dilatrane A.P. bead filled capsules) to compare the i.v. pharmacokinetic profiles when taken with an hyperlipidic meal and a balanced standard meal. Each subject took part in four phases in randomised order, corresponding to all possible combinations of the products and the types of meal. Each phase involved a single dose of 9 to 11 mg·kg−1 theophylline administered at 20.00 h, at the beginning of the meal, with 100 ml water. The two formulations were found to be bioequivalent with both types of meal. Taken with a balanced meal, the mean parameters were similar; for Theo-Dur and Dilatrane A.P. they were respectively: Cmax: 11.32 mg·l−1 which plateaued from 8 to 10 h after dosing and 10.9 mg·l−1, which plateaued after 6 to 10 h; AUC 230 mg·h·l−1 and 220 mg·h·l−1; and MRT 18.2 h and 17.7 h. After the hyperlipidic meal the values for Theo-Dur and Dilatrane A.P. respectively, were: Cmax 10.9 mg·l−1 at 12 h and 11.3 mg·l−1 at 10 h; AUC 237 mg·h·l−1 and 227 mg·h·l−1; and MRT 19.2 h and 18.9 h. In spite of a decrease in the absorption rate, which led to a shift to the right of about 2 h of the plasma concentration-time curve, the bioavailability of both formulations were not significantly modified by a hyperlipidic meal as compared to a balanced meal. The shift of the curve with fatty food was not clinically important, as there was no dumping effect. The main difference between the two formulations was seen during the absorption phase, which was linear and less variable with Dilatrane A.P. and sigmoidal with Theo-Dur. This was observed with both types of meal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609431
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  • 108
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of midazolam in patients recovering from cardiac surgery (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 161-166 
    Details
    ISSN: 1432-1041
    Keywords: midazolam ; benzodiazepine ; pharmacokinetics ; biotransformation ; surgery ; prolonged recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of midazolam has been studied in patients recovering from cardiac surgery, who required sedation for postoperative mechanical ventilation. Twelve males (mean age 64.5 years) with severe heart disease received an infusion of midazolam 15 mg·h−1 for 4 h, starting 1 to 3 h post surgery. Multiple blood samples were collected from each patient during the infusion and up to 48–93 h after it. The pharmacokinetic parameters of midazolam were determined using both moment analysis and the program NONMEM. The average terminal half-life was 10.6 h. The prolonged elimination was mainly due to a decrease in its metabolic clearance (0.25 l·min−1). The maintenance infusion dose of midazolam in such patients should be reduced. The time to recovery after stopping an infusion depends upon the amount of drug in the body at that time and a simulation of the plasma concentrations after various infusion regimens suggests that recovery will be delayed after prolonged (〉48 h) administration of midazolam to these patients. However, after shorter infusions (〈12 h), redistribution of the drug away from the site of action was still occurring and recovery would be expected to be relatively rapid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558225
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  • 109
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of ketoprofen enantiomers in cholecystectomy patients: influence of probenecid (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 589-594 
    Details
    ISSN: 1432-1041
    Keywords: ketoprofen ; probenecid ; cholecystectomy ; enantiomers ; glucuroconjugates ; stereoselectivity ; T-tube patients ; biliary excretion ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ketoprofen (KT), a 2-arylpropionic acid nonsteroidal antiinflammatory drug, is administered as a racemate. Previous reports suggest stereoselective biliary excretion of KT enantiomers. This hypothesis was tested by administering 50 mg racemic KT to five patients who required bile drainage following cholecystectomy surgery. Subsequently, to study the influence of probenecid (PB), an inhibitor of KT renal elimination, on the biliary excretion, 1000 mg PB was administered 1.5 h before KT to the same patients. The unchanged and conjugated (as glucuronides) KT enantiomers were measured in plasma, urine and bile. In general, KT enantiomers had different plasma concentration-time curves. As compared to normal subjects, these patients had comparable AUCs and shorter t1/2s. Biliary concentrations of conjugated S-KT were greater than R-KT. Nevertheless, the total cumulative biliary excretion of conjugated KT did not exceed 2% of the dose ruling out this pathway as a significant route of KT elimination. There was a positive and significant correlation between the cumulative urinary excretion of conjugated KT enantiomers and creatinine clearance. Although PB did not influence the pattern of stereoselectivity of KT, it increased AUC and prolonged t1/2 of the enantiomers. While reducing cumulative urinary excretion, PB increased total biliary elimination of conjugated KT enantiomers. This, however, did not totally compensate for the reduced urinary excretion. It is suggested that the impaired conjugation of KT caused by PB administration may result in the augmentation of other, otherwise minor, metabolic pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00562550
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  • 110
    Electronic Resource
    Electronic Resource
    Circadian variation in the pharmacokinetics of verapamil (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 613-615 
    Details
    ISSN: 1432-1041
    Keywords: verapamil ; pharmacokinetics ; circadian rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Circadian variation in the metabolism of verapamil was investigated in 10 patients with stable angina pectoris during treatment with sustained-release verapamil 360 mg at 08.00 h or 22.0 h. No major difference in exercise parameters was found. During the evening dosage schedule a significantly greater bioavailability (AUC) and a prolonged time to peak concentration was found. During the night (24.00 h–06.00 h) the half-life of verapamil was significantly longer than during the day (16.00 h–22.00 h). These differences in pharmacokinetics may be due to reduced hepatic blood flow at night or to circadian variation in hepatic microsomal metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00562555
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  • 111
    Electronic Resource
    Electronic Resource
    Mitochondrial encephalomyopathy with pilovacuolar inclusion or phenocopy with mitochondrial artefact? (1989)
    Springer
    Journal of neurology 236 (1989), S. 361-363 
    Details
    ISSN: 1432-1459
    Keywords: Mitochondrial encephalomyopathy ; MELAS ; Mitochondrial inclusion ; Pilovacuolar inclusion ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The case of a 33-year-old man with clinical features of mitochondrial encephalomyopathy is presented. He suffered from recurrent cerebral infarctions, cerebellar ataxia, deafness, retinopathy, weakness, and cardiac and renal disorders. Biochemical and light microscope investigations of skeletal muscle did not show any mitochondrial abnormality. Electron microscopy revealed the presence of a hitherto unreported peculiar “pilovacuolar” inclusion in numerous mitochondria, composed of an electron dense pile or rod within a vacuole, while globular or crystalline inclusions were absent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314383
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  • 112
    Electronic Resource
    Electronic Resource
    Localization of aggregation substances of Enterococcus faecalis after induction by sex pheromones (1989)
    Springer
    Archives of microbiology 151 (1989), S. 491-497 
    Details
    ISSN: 1432-072X
    Keywords: Aggregation substance ; Enterococcus faecalis ; Electron microscopy ; Field emission scanning electron microscopy ; Immunogold labelling technique ; Sex pheromone system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The distribution of sex pheromone induced aggregation substance was studied on the cell surface of various Enterococcus faecalis strains. In the accompanying paper we have shown that the aggregation substance appears as a layer of hairlike structures. Using direct and indirect immunogold technique, transmission electron microscopy and high resolution scanning electron microscopy we investigated the appearance and distribution of the aggregation substance. The “hairs” increase in number with increasing exposure to sex pheromones (maximum density: 1300/μm2). We show that these structures are unequally distributed over the cell surface, even if the cells were induced by sex pheromones for a long period of time. Statistical analysis of the unequal distribution indicates that aggregation substance is incorporated into pre-existing “old” cell-walls and that this incorporation shows a saturation ca. 40 min after addition of sex pheromones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454864
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  • 113
    Electronic Resource
    Electronic Resource
    Electron-microscopic study on the anterior pituitary gland of spontaneous dwarf rats (1989)
    Springer
    Cell & tissue research 258 (1989), S. 477-482 
    Details
    ISSN: 1432-0878
    Keywords: Anterior pituitary gland ; Electron microscopy ; Growth hormone ; Spontaneous dwarf rats (dr/dr)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The spontaneous dwarf rat is a novel experimental model animal on the study of pituitary dwarfism. The fine structure of the anterior pituitary cells was studied in the immature and mature dwarf rats. Pituitary glands were removed from 5-, 10-, 20-day-old immature dwarfs, adult (45 days-16 weeks) dwarfs and normal 3-month-old rats and processed for electron-microscopic observation. In the control animals, growth hormone cells were readily identified by their ultrastructural characteristics, such as the presence of numerous electron-dense secretory granules, 300–350 nm in diameter, well developed rough endoplasmic reticulum and a prominent Golgi complex. In contrast, growth hormone cells were not found in the anterior pituitary gland of the spontaneous dwarf rat at any age examined. Other pituitary cell types, i.e., luteinizing hormone/ follicle stimulating hormone, thyroid stimulating hormone, adrenocorticotropic hormone and prolactin cells, appeared similar in their fine structure to those found in the control rats. In the pituitary gland of dwarf rats, a number of polygonal cells were observed either with no or relatively few secretory granules. The rough endoplasmic reticulum was arranged in parallel cisternae and the Golgi complex was generally prominent in these cells. In addition, many were found to have abundant lysosomes. A few minute secretory granules were occasionally observed; however, the immunogold technique failed to localize growth hormone or prolactin in the granules. The nature of these cells remained obscure in this study. Since their incidence and fine structural features, other than the secretory granules, were quite similar to those of the growth hormone cells in normal rats, we postulate that these cells are dysfunctional growth hormone cells. These results suggest that the cause of the growth impairment in the spontaneous dwarf rat is due to a defect in the functional growth hormone cells in the pituitary gland, and since other pituitary cell types appeared normal, the disorder seems to be analogous to the isolated growth hormone deficiency in the human.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218859
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  • 114
    Electronic Resource
    Electronic Resource
    Light- and electron-microscopic investigation of the rat subcommissural organ grafted under the kidney capsule, with particular reference to immunocytochemistry and lectin histochemistry (1989)
    Springer
    Cell & tissue research 258 (1989), S. 499-514 
    Details
    ISSN: 1432-0878
    Keywords: Subcommissural organ ; Secretory activity, neural control ; Transplantation ; Long-spacing collagen ; Immunocytochemistry ; Molecular markers (neuronal, glial) ; Electron microscopy ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary There is increasing evidence that, in the rat, a serotonin-mediated neural input may have an inhibitory influence on the secretory activity of the subcommissural organ (SCO). In the present investigation the rat SCO was studied 7, 30 and 90 days after transplantation under the kidney capsule, an area devoid of local serotonin-containing nerves. The grafted tissue was examined by use of immunocytochemistry employing a series of primary antisera, lectin histochemistry and transmission electron microscopy. The grafted SCO survived transplantation and contained, in addition to secretory ependymal and hypendymal SCO-cells, also elements immunoreactive with antisera against glial fibrillary acidic protein or S-100 protein. In transplants, SCO-cells produced a material displaying the characteristic immunocytochemical and lectin-binding properties of SCO-cells observed under in-situ conditions. The ependymal cells lined 1–3 small cavities, which contained secretory material. A fully developed structural equivalent of Reissner's fiber was, however, never found. The immunocytochemical and ultrastructural study of the grafted SCO showed an absence of nerve fibers within the graft and suggested a state of enhanced secretory activity. A network of protruding basal lamina structures connected the secretory cells to the newly formed capillaries revascularizing the SCO. One week after transplantation, long-spacing collagen started to appear in expanded areas of such laminar networks and also in the perivascular space. It is suggested (i) that the formation of long-spacing forms of collagen is triggered by factors provided by the SCO-secretory cells, and (ii) that secretory material of the ependymal and hypendymal cells may reach the reticular extensions of the basal lamina. In contrast to the SCO in situ, the grafted SCO-cells showed a positive immunoreaction for neuron-specific enolase. They became surrounded by a S-100-immunoreactive glial sheath that separated them from other transplanted cell types and the adjacent kidney tissue of the host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218862
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  • 115
    Electronic Resource
    Electronic Resource
    Localization of cholesterol in the colonic epithelium of the guinea pig: regional differences and functional implications (1989)
    Springer
    Cell & tissue research 258 (1989), S. 339-347 
    Details
    ISSN: 1432-0878
    Keywords: Proximal colon ; Distal colon ; Cholesterol ; Filipin ; Freeze-fracture ; Electron microscopy ; Guinea Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It is generally accepted that variations in membrane cholesterol content affect the fluidity of the bilayer, thus altering its permeability. In the biological membranes, in physiological conditions, a high cholesterol content rigidifies the bilayer decreasing its permeability, a lower cholesterol content induces the opposite effect by increasing the permeability. Since differences in the epithelial permeability for short chain fatty acids have previously been demonstrated in the proximal and distal colon of the guinea pig, these two regions were investigated to establish whether differences in membrane cholesterol content of the absorbing cells can be demonstrated. Freeze-fracture replicas of filipin-treated colonic tissue were used. The results show that in the proximal colon the density of filipin cholesterol complexes located on the luminal plasma membrane of the columnar absorbing cells was significantly higher (about twice) than in the distal colon. Therefore the lower amount of cholesterol present in the membrane of the absorbing cells in the distal colon indicates a greater fluidity of the membranes of the epithelial cells in this region. Such fluidity could be correlated to the higher absorption rates of shortchain fatty acids characteristic of this region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00239454
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  • 116
    Electronic Resource
    Electronic Resource
    Quantitative electron microscopy of endocrine cells in oxyntic mucosa of normal human stomach (1989)
    Springer
    Cell & tissue research 255 (1989), S. 41-48 
    Details
    ISSN: 1432-0878
    Keywords: Stomach ; Endocrine cells ; Electron microscopy ; Morphometry ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural morphometric study of the endocrine cells of the oxyntic mucosa of the stomach in gastric biopsies collected from five male and five female healthy volunteers aged 19–31 was performed. No sex-related differences were disclosed. Endocrine cells accounted for 1.2±0.4% of the epithelial volume and 0.9±0.4% of the mucosal volume, i.e., including the lamina propria. After classification of the specific endocrine cell types according to the ultrastructural morphology of secretory granules, the volume densities of ECL, P and D cells (30±9%, 24±7%, and 22±4% of the entire endocrine cell mass, respectively) were higher than those of other endocrine cell types. In particular, EC cells contributed less than 10% and X cells represented a very low proportion of the total cells. Non-granulated profiles of cells which in all other respects appeared to be endocrine were also found with a volume density of 8±4%. D cells were distinguished by the high fraction of cytoplasm occupied by secretory granules (31±5%). Subdivision of the whole mucosa into four horizontal segments revealed the endocrine cells to be mostly distributed in the three lower, with virtually no endocrine cells in the superficial segment. The quantitative ultrastructural analysis of the endocrine cell population of the normal human oxyntic mucosa provided by this study may allow a better evaluation of physiological and pharmacological variations of the endocrine cell population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229064
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  • 117
    Electronic Resource
    Electronic Resource
    Vasoactive intestinal polypeptide (VIP)- and neuropeptide Y (NPY)-containing nerve fibres in the penile cavernous tissue of green monkeys (Cercopithecus aethiops) (1989)
    Springer
    Cell & tissue research 256 (1989), S. 529-541 
    Details
    ISSN: 1432-0878
    Keywords: Penile erection ; Electron microscopy ; Immunohisto(cyto)chemistry ; Vasoactive intestinal polypeptide (VIP) ; Neuropeptide Y (NPY) ; Cercopithecus aethiops (Primates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cavernous body of green monkeys contains many unmyelinated and few myelinated axons. The unmyelinated axons form terminals in the adventitia of the arteries, between trabecular muscle cells, in the interstitium, and close to endothelium cells of the sinuses. All terminals displayed predominantly “small clear vesicles” and very few “large granular vesicles”; “small granular vesicles” were not seen. However, in rabbit penises, terminals with many large granular vesicles are prominent. Immunohistochemistry (PAP technique) showed a dense network of VIP- and NPY-reactive fibres around the arteries and around trabecular muscles. The density of nerve fibres was particularly high around the subendothelial cushions of the helicine arteries. Double staining for NPY and VIP revealed that both peptides were colocalized. Immunocytochemistry (preembedding PAP technique) showed VIP- and NPY-reactivity in terminals with small clear vesicles; the reaction product was bound to the cytoplasmic face of different membrane types. Although the intracellular localization of the reaction product is probably due to artefactual displacement during preparation, the uniformity of the terminals questions the view that large and small granular vesicles in all species characterize peptidergic and noradrenergic terminals, respectively. The essential findings can be summarized as (1) a high degree of uniformity of nerve terminals, (2) colocalization of VIP and NPY, (3) heavy innervation of the subendothelial cushions of the helicine arteries, and (4) possible innervation of endothelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225601
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    Immature rat epididymal epithelial cells grown in static primary monolayer culture on permeable supports (1989)
    Springer
    Cell & tissue research 256 (1989), S. 573-580 
    Details
    ISSN: 1432-0878
    Keywords: Epididymis ; Epithelium ; Monolayer culture ; Histochemistry ; Electron microscopy ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary N-acetylglucosaminidase (NAG), acid phosphatase (ACP) and alkaline phosphatase (AKP) were localised histochemically in fixed cells from the 37-day-old rat epididymis grown in static monolayer culture for 2–8 days. ACP and NAG were cytosolic enzymes found in perinuclear positions, whereas staining of AKP was consistent with a membranous position. These enzymes were also examined in frozen tissue sections of the epididymis, from rats of the equivalent age, where NAG had intense activity in both supra- and infra-nuclear cytoplasm and ACP was more active apically. For the first time AKP was localised along basolateral membranes of the epithelium and in the lumen of the mid-caput region. The monolayer in culture was of principal cells only and they maintained their polarity and ultrastructural characteristics, but the height of the cells was reduced compared to that obtained in situ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225606
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    Granulated peripolar epithelial cells in the renal corpuscle of marine elasmobranch fish (1989)
    Springer
    Cell & tissue research 257 (1989), S. 61-67 
    Details
    ISSN: 1432-0878
    Keywords: Kidney ; Peripolar cells ; Renal corpuscle ; Electron microscopy ; Raja erinacea, Mustelus canis, Rhinoptera bonasus, Sphryna lewini, Rhizoprionodon terraenovae, Squalus acanthias (Elasmobranchii)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Granulated epithelial cells at the vascular pole of the renal corpuscle, peripolar cells, have been found in the kidneys of five species of elasmobranchs, the little skate (Raja erinaced), the smooth dogfish shark (Mustelus canis), the Atlantic sharpnose shark (Rhizoprionodon terraenovae), the scalloped hammerhead shark (Sphryna lewini), and the cow-nosed ray (Rhinoptera bonasus). In a sixth elasmobranch, the spiny dogfish shark (Squalus acanthias), the peripolar cells could not be identified among numerous other granulated epithelial cells. The peripolar cells are located at the transition between the parietal epithelium of Bowman's capsule and the visceral epithelium (podocytes) of the glomerulus, thus forming a cuff-like arrangement surrounding the hilar vessels of the renal corpuscle. These cells may have granules and/or vacuoles. Electron microscopy shows that the granules are membrane-bounded, and contain either a homogeneous material or a paracrystalline structure with a repeating period of about 18 nm. The vacuoles are electron lucent or may contain remnants of a granule. These epithelial cells lie close to the granulated cells of the glomerular afferent arteriole. They correspond to the granular peripolar cells of the mammalian, avian and amphibian kidney. The present study is the first reported occurrence of peripolar cells in a marine organism or in either bony or cartilagenous fish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221634
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    Gestational changes in hamster adrenal cortex: Morphometric and ultrastructural stereologic studies (1989)
    Springer
    Cell & tissue research 256 (1989), S. 241-246 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal cortex ; Pregnancy ; Electron microscopy ; Stereology ; Golden hamster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the hamster, the weight of the adrenal glands increases during the course of gestation, with the highest value at day 5. In comparison to non-pregnant control animals, there were no changes in the volume of the zona glomerulosa (ZG) and zona fasciculata (ZF), while the volume of the zona reticularis (ZR) increased notably. The average volume of ZG-cells rose at day 5 of pregnancy and thereafter gradually decreased to that of control hamsters. A marked drop in the volume of ZF-cells was seen at days 5 and 10 of pregnancy, whereas at day 15 the cells were larger than in controls. At day 5 of pregnancy, a conspicuous increase in the cell volume was found in ZR, followed by lower values at day 10 and again higher than in control hamsters at day 15. The total number of parenchymal cells in hamster adrenal cortex increased at day 10 of gestation, then underwent a marked decrease, reaching the control value at the final day of pregnancy; this drop was mainly due to a reduction in the number of ZF-cells. The changes in the cell volume were paralleled by rather proportional changes in the volume of the mitochondrial compartment and in the quantity of smooth endoplasmic reticulum. The volume of the lipid-droplet compartment significantly rose in the course of gestation in both ZF- and ZR-cells. The cortisol output by adrenal homogenates gradually decreased during pregnancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218881
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    Two types of mammosomatotropes in mouse adenohypophysis (1989)
    Springer
    Cell & tissue research 256 (1989), S. 645-648 
    Details
    ISSN: 1432-0878
    Keywords: Mammosomatotropes ; Adenohypophysis ; Electron microscopy ; Immunohistochemistry ; Mouse (SMA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two types of mammosomatotropes (MS), the small-granule and vesicle-granule MS, were detected in mouse adenohypophysis by electron microscopy and immunohistochemistry. Both cell-types were immunoreactive to prolactin (PRL) and growth hormone (GH) antisera. The small-granule MS contained small, round, solid secretory granules about 100 nm in diameter, and were smaller than the classical GH and PRL cell-types. The vesicle-granule MS contained secretory granules like cored vesicles, and were larger than classical GH and PRL cells. Small-granule MS were immunoreactive to both PRL and GH antisera in the same region of the cell cytoplasm; the vesicle-granule MS, however, were immunoreactive to only PRL antiserum in most cytoplasmic areas, and a positive response to both PRL and GH antisera was confined to only certain small areas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225615
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    Nasal lymphoid tissue in the rat (1989)
    Springer
    Cell & tissue research 255 (1989), S. 193-198 
    Details
    ISSN: 1432-0878
    Keywords: Mucosa-associated lymphoid tissue ; Nose ; Lymphoepithelium ; Electron microscopy ; Immunohisto-chemistry ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure and organization of paired lymphoid tissue in the nasal mucosa, situated in the transitional zone on both sides of the septal opening to the pharyngeal duct, of conventionally-housed rats was examined by light microscopy and scanning and transmission electron microscopy. Each lymphoid structure consisted of follicles containing T- and B-cell areas, and was covered with specialized epithelium. This epithelium consisted of cuboidal ciliated cells with oval nuclei parallel to the basal lamina. Goblet cells were sparse. Occasionally, islands of microvilli-bearing cells (so called membraneous or M cells) covered the lymphoid structures. M Cells were also found as single cells among the ciliated cells. The morphological characteristics and the particular localization justify the conclusion that the nasal lymphoid tissue described belongs to the mucosa-associated lymphoid tissue. It is therefore suggested that this nasal structure be designated nasal lymphoid tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229081
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    Immunocytochemical and ultrastructural studies on allografts of the pituitary neurointermediate lobe in the third cerebral ventricle of the rat (1989)
    Springer
    Cell & tissue research 255 (1989), S. 393-404 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Neural lobe ; Intermediate lobe ; Intraventricular graft ; Immunocytochemistry ; Electron microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neurointermediate lobes from adult or 10-dayold rats were implanted by a stereotaxic procedure into the third ventricle of adult male rats, in an area close to the paraventricular nucleus. They were examined, using immunocytochemical and ultrastructural techniques, at times ranging from 1 week to 8 months. All grafts were recovered in a healthy condition although some rejection of the tissue was detected at the 1and 2-week stages. In the neural lobe, clusters of pituicytes were scattered among the loose network of capillaries, most of which had a fenestrated endothelium. The intermediate lobe remained organized in compact avascular lobules. Axons similar to those projecting into the neurointermediate lobe in situ, but also axons of other types (e.g., somatostatinergic, enkephalinergic) penetrated the grafts. Synapses with melanotrophic cells in the intermediate lobe and neurohaemal contacts in the neural lobe were frequent from 2 1/2 months after transplantation. Immunocytochemical and ultrastructural characteristics indicated intense secretory stimulation of the melanotrophic cells in the early stages. All cells enclosed in a same glandular lobule reacted in a similar manner. In later stages, when re-innervation occurred, the cells recovered their initial characteristics. The overall effect of the re-innervation of the intermediate lobe grafted in this location is inhibitory, as in the lobe in situ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224123
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    Glomerular podocytes in cultured rat kidney slices (1989)
    Springer
    Cell & tissue research 256 (1989), S. 419-429 
    Details
    ISSN: 1432-0878
    Keywords: Kidney ; Glomerulus ; Podocytes ; Tissue culture ; Electron microscopy ; Morphometry ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of rat glomerular epithelial cells (podocytes) in kidney slices in vitro was examined using qualitative and quantitative electron microscopy. The kidney slices were cultured in Medium 199 with Hanks' salts in a 5% CO2/95% O2 environment for up to 14 days. Few changes in podocyte ultrastructure occurred in the first 12 h of culture, but by 24 h cell bodies were rounded, microvilli were present on all podocyte surfaces, and some foot processes had been replaced by flattened expanses of cytoplasm. These changes were more pronounced by 3 days, when some podocytes had developed pseudopodal extensions and appeared to be migrating from glomeruli onto the slice surface. Podocytes could still be identified after 8, 10 and 14 days of culture, although relatively few glomeruli remained at 14 days. Morphometric methods were used to analyse podocyte shape, volume and surface area during the first 4 days of culture. The most significant change involved loss of foot processes: the number of filtration slits per 100 μm of basement membrane decreased from 211.8 ± 15.0 (mean ± SD) at the commencement of culture, to 55.3 ± 22.6 after 2 days (P 〈 0.001). These data provide baseline information for in vitro studies on the effects of nephrotoxins on podocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218900
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    Mean residence time for drugs subject to enterohepatic cycling (1989)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 17 (1989), S. 327-345 
    Details
    ISSN: 1573-8744
    Keywords: enterohepatic recirculation ; pharmacokinetics ; hepatic extraction ; area under the first moment curve ; model ; bile ; mean residence time ; mean absorption time ; formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A physiologically realistic model of enterohepatic cycling (EHC) which includes separate liver and gallbladder compartments, discontinuous gallbladder emptying and first-order absorption from both an oral formulation and secreted bile (ka po and ka b, respectively) has been developed. The effect of EHC on area under the first-moment curve (AUMC) of drug concentration in plasma and on parameters derived from the AUMC was investigated. Unlike AUC, AUMC is dependent on the time and time-course of gallbladder emptying, increasing as the interval between gallbladder emptying increases. Consequently, mean residence time (MRT) is also a time-dependent parameter. Analytical solutions for MRTiv and MRTpo were derived. Mean absorption time (MAT = MRTpo — MRTivj is also time-dependent, contrary to findings previously published for a model of EHC with a continuous time lag. MAT is also dependent on k a po , k a b and the hepatic extraction ratio. The difference between MRT po s two formulations with unequal k a po values may deviate from the difference in the inverse of their absorption rate constants. Implications for design and interpretation of pharmacokinetic studies include (i) MAT values may be dominated by the time-course of recycling rather than the time-course of the initial absorption, depending on the extent of EHC and (ii) the unpredictable nature of the time of gallbladder emptying will contribute to intrasubject variability in derived parameters during crossover studies. Knowledge of the extent of EHC is invaluable in deciding whether modification of the in vitro release characteristics of an oral formulation will have any effect on the overall time-course of absorption in vivo. Techniques to monitor or control gallbladder emptying may be helpful for reducing variability in pharmaco-kinetic studies for compounds which are extensively cycled in bile.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01061900
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    The kinetic disposition and dosage regimen for carbenicillin in buffalo calves (1989)
    Springer
    Veterinary research communications 13 (1989), S. 389-394 
    Details
    ISSN: 1573-7446
    Keywords: buffalo ; carbenicillin ; pharmacokinetics ; therapeutics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The distribution half-life, elimination half-life, apparent volume of distribution and total body clearance of carbenicillin in healthy buffalo calves following a single intravenous administration (50 mg/kg) were 0.057±0.005 h, 1.688±0.11 h, 0.185±0.021 L kg-1 and 75.97±6.519 ml kg-1 h-1 respectively. A satisfactory dosage regimen for carbenicillin in buffalo calves was calculated to be 56 mg/kg followed by 52 mg/kg body weight repeated at 6 h intervals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346071
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    The pharmacokinetics of volatile anesthetic agent elimination: A theoretical study (1989)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 17 (1989), S. 109-123 
    Details
    ISSN: 1573-8744
    Keywords: anesthetics, gases ; pharmacokinetics ; volatile anesthetics ; inhalation agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The theoretical groundwork for a rate constant formulation of inhaled anesthetic elimination kinetics is discussed. In an effort to simulate recent experimental results a linear flow-limited five-compartment model was used comprising lung, vessel-rich tissue, muscle, nonvisceral fat, and an additional compartment, marrow-visceral fat whose functional existence recently has been experimentally demonstrated. Hypothetical but plausible parameters for the marrow-visceral fat compartment were used. The theoretically predicted values were in good agreement with experimental results suggesting that this model is appropriate for the elimination kinetics of agents that are not metabolized to any significant degree. Simple approximate expressions for the rate constants were also derived and were in reasonable agreement with experimental results. The model was also employed to clarify the effect of anesthetic duration on subsequent elimination kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059090
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    Drug- or hormone-induced adaptation: Model of adrenergic hypersensitivity (1989)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 17 (1989), S. 347-364 
    Details
    ISSN: 1573-8744
    Keywords: hypersensitivity ; propranolol ; pharmacokinetics ; pharmacodynamics ; modeling ; β receptor ; adrenergic stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A pharmacokinetic/pharmacodynamic model of hypersensitivity to adrenergic stimulation following abrupt withdrawal of chronic β blockade was developed. The model employs the Hill equation, a term which describes the competition between isoproterenol and l- propranolol for β receptors, and a kinetic term which characterizes the appearance and disappearance rates of up-regulated β receptors. The model predicted peak chronotropic hyperresponsiveness to isoproterenol 48 hr following abrupt withdrawal of chronic treatment with daily propranolol doses of 160 mg, and a drug half-life of 3.5 hr. The model also predicted that increasing the dose rate and prolonging the half-life of propranolol delayed and decreased the extent of adrenergic hypersensitivity. The time-course of adrenergic hypersensitivity simulated by our model was in excellent agreement with that observed in studies which were published earlier by our laboratory. The model underestimated the extent of adrenergic hypersensitivity. The results of our simulation are consistent with a β agonist-receptor-effector system, which involves spare receptors, amplification of response by second and third messengers, and β agonist-antagonist-induced receptor regulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01061901
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    Effect of propranolol on the myocardial contractility of normotensive and spontaneously hypertensive rabbits: Relationship of pharmacokinetics and pharmacodynamics (1989)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 17 (1989), S. 551-570 
    Details
    ISSN: 1573-8744
    Keywords: propranolol ; pharmacokinetics ; pharmacodynamics ; myocardial contractility ; hypertensive ; rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Myocardial contractility of normotensive and spontaneously hypertensive rabbits was determined following an iv bolus injection of propranolol HCl. Left ventricular pressure and dimension were used to calculate the contractility parameters of (dP/dt) max ,maximum fiber shortening velocity V cf , and the slope of the end systolic pressure-end systolic volume line (ESP-ESV line). Hypertension was induced by a methoxamine HCl iv infusion which mimicked the cardiac effects seen in essential hypertension. Propanolol caused a significant decrease in all contractility parameters (p〈0.05)within 15min after administration, with a peak effect occurring after 30–35 mins. The pharmacokinetics and pharmacodynamics of propranolol were fit using Hill's equation in conjunction with the concentration of drug in the theoretical effect compartment. The normotensive group of rabbits had a calculated EC (50) of 12.7 ng/ml, while the hypertensive group had an EC 50 of 6.9 ng/ml,indicating that the hypertensive rabbits were much more sensitive to the propranolol than the normotensive group. In addition, the normotensive group of rabbits demonstrated a much different pharmacokinetic-pharmacodynamic relationship than that of the hypertensive group, indicating that the hypertensive state of the animal has a significant effect upon the concentration-effect relationship.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01071349
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    The influence of assay variability on pharmacokinetic parameter estimation (1989)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 17 (1989), S. 571-592 
    Details
    ISSN: 1573-8744
    Keywords: pharmacokinetics ; variability ; parameter estimation ; modeling ; nonlinear regression ; Wagner-Nelson method ; mixed effects models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The impact of assay variability on pharmacokinetic modeling was investigated. Simulated replications (150) of three “individuals” resulted in 450 data sets. A one-compartment model with first-order absorption was simulated. Random assay errors of 10, 20, or 30% were introduced and the ratio of absorption rate (K a )to elimination rate (K e )constants was 2, 10, or 20. The analyst was blinded as to the rate constants chosen for the simulations. Parameter estimates from the sequential method (K e )estimated with log-linear regression followed by estimation of K a and nonlinear regression with various weighting schemes were compared. NONMEM was run on the 9 data sets as well. Assay error caused a sizable number of curves to have apparent multicompartmental distribution or complex absorption kinetic characteristics. Routinely tabulated parameters (maximum concentration, area under the curve, and, to a lesser extent, mean residence time) were consistently overestimated as assay error increased. When K a /K e =2,all methods except NONMEM underestimated K e ,overestimated K a ,and overestimated apparent volume of distribution. These significant biases increased with the magnitude of assay error. With improper weighting, nonlinear regression significantly overestimated K e when K a /K e ,=20. In general, however, the sequential approach was most biased and least precise. Although no interindividual variability was included in the simulations, estimation error caused large standard deviations to be associated with derived parameters, which would be interpreted as interindividual error in a nonsimulation environment. NONMEM, however, acceptably estimated all parameters and variabilities. Routinely applied pharmacokinetic estimation methods do not consistently provide unbiased answers. In the specific case of extended-release drug formulations, there is clearly a possibility that certain estimation methods yield K a and relative bioavailability estimates that would be imprecise and biased.
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    URL: http://dx.doi.org/10.1007/BF01071350
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    Mallomonas alphaphora (Chrysophyceae), a new species from Western Australia (1989)
    Springer
    Plant systematics and evolution 164 (1989), S. 209-214 
    Details
    ISSN: 1615-6110
    Keywords: Algae ; Chrysophyceae (Synurophyceae) ; Mallomonadaceae ; Mallomonas alphaphora ; Electron microscopy ; phytoplankton ; scale-bearing flagellate ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new species ofMallomonas, M. alphaphora (Chrysophyceae), was found in freshwater ponds in the Perth region, Western Australia. It is distinguished from other species ofMallomonas by its very distinctive scale and bristle morphology and is placed in a new section,Alphaphorae, of the genusMallomonas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00940438
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    Revascularization of isolated autologous bone grafts following microsurgical implantation of arteries and veins (1989)
    Springer
    European journal of plastic surgery 12 (1989), S. 29-34 
    Details
    ISSN: 1435-0130
    Keywords: Revascularization ; Vessel implantation ; Bone grafts ; Corrosion casts ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The microsurgical implantation of a saphenous vascular axis into free transplanted autologous isolated rib segments in Beagle dogs led to complete revascularization of the bone after two, three and four weeks. Indian ink and Mercox-injected specimens showed a vascular network which penetrated the entire cortical layer. Semi-thin sections revealed osteoblasts and osteoclasts visible in the canals of the revascularized cortical layer, while the control specimen without vessel implantation showed nothing but ground substance. The revascularized bones did not contain any necrotic areas. The newly formed vascular system consisted of arteries, veins and their anastomoses. The veins appeared to produce a greater number of new vessels than the arteries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226918
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    Effects of two isomeric 1-aminoadamantanes on the membrane anisotropy and on alpha- and gamma-motoneurones excitability (1989)
    Springer
    Journal of neural transmission 1 (1989), S. 153-164 
    Details
    ISSN: 1435-1463
    Keywords: Aminoadamantanes ; pharmacokinetics ; CNS ; membrane anisotropy ; excitability ; spinal alpha- and gamma-motoneurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The structure-activity relationship of two isomeric 1-aminoadamantanes, 1-C-ethylaminoadamantane (D 174) and 1-amino-3-ethyladamantane (D 175), on membrane anisotropy and the excitability of neurons was studied in the CNS of the rat and in the decerebrated cat. Mass spectrometric analysis showed that after a single, 40 mg/kg dose, D 174 and D 175 were unevenly distributed within the CNS of the rat, moreover the distribution pattern of the two substances was different. As measured by fluorescence depolarization in controls the membrane anisotropy was found to be higher in the older parts as compared with the younger parts of the CNS. After i.p. application of 40 mg/kg the membrane anisotropy was reduced in the cortex by D 174, whereas D 174 and D 175 increased the rigidity in striatal membranes. If cortical membranes were incubated with the substances, the fluidizing effect of D 174 was more prominent than that of D 175. In the decerebrated cat only D 174 in a dose of 5 mg/kg i.p. raised the discharge of spinal alpha-motoneurones significantly. The results suggest that the membrane architecture is more affected by D 174 as compared with D 175 which is reflected by a greater effect on membrane anisotropy as well as on the activity of spinal alpha-motoneurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02248665
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    Verapamil disposition and cardiovascular effects in elderly patients after single intravenous and oral doses (1989)
    Springer
    Cardiovascular drugs and therapy 3 (1989), S. 417-425 
    Details
    ISSN: 1573-7241
    Keywords: verapamil ; elderly ; pharmacokinetics ; cardiovascular effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pharmacokinetics and pharmacodynamics of verapamil were studied in 11 elderly subjects (age=79.67±4.74 years) and in 11 middle-aged subjects (age=45±11.37 years) following intravenous (IV), single oral, and long-term oral administration. Plasma verapamil concentrations were determined using high-pressure liquid chromatography (HPLC). Twenty-four hour dynamic Holter electrocardiographic (ECG) recordings were employed to study heart rate (HR) and P-R interval. No difference in plasma half-life, distribution volume, body clearance, and area under the curve (AUC) was observed between the two groups after IV and oral verapamil administration. Blood pressure (BP) and HR were significantly reduced after verapamil IV administration in the elderly group only (p〈0.05, p〈0.01, respectively). After single and long-term oral administration, variable HR and BP responses were observed in both groups. The P-R prolongation following both IV and single oral doses exhibited a delay with respect to the peak plasma concentration, inducing a definite hysteresis loop. The slope of P-R variations (using a linear pharmacodynamic model) was greater in the elderly both after IV and single oral verapamil administration, but statistical significance was obtained only after the single oral dose (p〈0.05). In the elderly group, after long-term oral administration, there was a significant prolongation of the P-R interval (p〈0.0001) with respect to the corresponding time point of the 24-hour predrug period. Such variations in pharmacodynamic parameters in the elderly did not, however, cause any clinical problem. In conclusion, verapamil seems to be well tolerated in the elderly as well as in younger patients at similar dosages. However, its use in the elderly requires careful clinical evaluation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01858113
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    Calcium channel antagonists: part VI: Clinical pharmacokinetics of first and second-generation agents (1989)
    Springer
    Cardiovascular drugs and therapy 3 (1989), S. 482-497 
    Details
    ISSN: 1573-7241
    Keywords: pharmacokinetics ; calcium antagonists ; liver disease ; renal disease ; hepatic enzymes ; metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A survey of the pharmacokinetic properties of the three prototypical calcium antagonist agents shows that they have in common a very high rate of hepatic first-pass metabolism with, in the case of verapamil and diltiazem, the formation of an active metabolite that affects the dose during chronic therapy. Therefore, the major factor altering the pharmacokinetic properties and the dose of the drug required is the capacity of the liver to metabolize the drug, which in turn depends on the hepatic blood flow and the activity of the hepatic metabolizing systems. Hence liver disease, a low cardiac output, and coadministration of certain drugs inducing or inhibiting the hepatic enzymes, all indirectly affect the pharmacokinetic properties of the calcium antagonists. There are also other potential drug interactions of a kinetic or dynamic nature that may arise. In general, renal disease has little effect on the pharmacokinetics of calcium antagonists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01865507
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  • 136
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    Effects of cardiovascular disease on pharmacokinetics (1989)
    Springer
    Cardiovascular drugs and therapy 3 (1989), S. 711-730 
    Details
    ISSN: 1573-7241
    Keywords: cardiovascular disease ; pharmacokinetics ; antiarrhythmics ; inotropics ; betablockers ; diuretics ; antihypertensives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The pathophysiologic changes occurring in cardiovascular disease can affect the kinetics of drugs in several different ways. The present review examines these modifications and the underlying mechanisms. The kinetics of specific agents, such as antiarrhythmic, antihypertensive, cardiotonic, and other drugs are considered, and the clinical implications are outlined. The clinician should be aware of these modifications, because they require an adjustment of the dosage regimen. A rational basis for a correct therapeutic choice can be provided by adequate knowledge of these modifications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01857622
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  • 137
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    A phase I trial of recombinant human interferon-γ in patients with Kaposi's sarcoma and the acquired immunodeficiency syndrome (AIDS) (1989)
    Springer
    Journal of clinical immunology 9 (1989), S. 351-361 
    Details
    ISSN: 1573-2592
    Keywords: Interferon-γ ; Kaposi's sarcoma ; human immunodeficiency virus (HIV) ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A Phase I study of recombinant interferon-gamma (rIFN-γ) was conducted to determine the toxicity and pharmacokinetics of this lymphokine in acquired immunodeficiency syndrome (AIDS) patients with Kaposi's sarcoma (KS). Sixteen patients with AIDS/KS were entered into a fixed-dose trial at either 0.001, 0.01, 0.1, or 1.0 mg/m2 of rIFN-γ. rIFN-γ was initially administered either as a single 24-hr continuous iv infusion or as a single im injection, followed 4 days later by a 10-day course of daily therapy by the same route. Following a 1-week washout period, this sequence of administration was then repeated, with the drug given by the alternate route. Pharmacokinetic analysis of the 1.0-mg/m2 group revealed that peak serum levels of up to 153 U/ml occurred 2–4 hr after im injection and that steady-state levels of up to 40 U/ml were reached approximately 7–12 hr after beginning iv infusion. Dose-related toxicities in this trial included fever, headache, fatigue, nausea, and hepatitis, all of which were most severe at the two highest doses. Dose-dependent depression of the total white blood-cell (WBC) count, affecting both granulocytes and lymphocytes, was the most common laboratory abnormality. Natural killer (NK)-cell activity was slightly enhanced at a dose of 0.1 mg/m2 but suppressed at 1.0 mg/m2 of drug; monocyte-mediated cytotoxicity, in contrast, was significantly increased only at the highest dose. No dose-related changes were noted in KS lesions, HLA-DR expression by peripheral blood mononuclear cells, lymphocyte blastogenesis, or the ability to culture cytomegalovirus (CMV) from body fluids. We conclude that a maximally tolerated dose (MTD) for this drug is in the range of 0.1–1.0 mg/m2 and that at least modest evidence of systemic immunomodulation may be seen when rIFN-γ is given at doses at or near this MTD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00918667
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  • 138
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    An experimental study of mucociliary pathology of the eustachian tube in otitis media with effusion induced by irradiation (1989)
    Springer
    European archives of oto-rhino-laryngology and head & neck 246 (1989), S. 428-432 
    Details
    ISSN: 1434-4726
    Keywords: Otitis media with effusion ; Mucociliary system ; Eustachian tube ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have examined the function and fine structure of the mucociliary system of the eustachian tube in an experimental study of otitis media with effusion induced by X-ray irradiation. Functional examination demonstrated that the ciliary activity was diminished in such a condition, while morphological observations showed pathological findings including compound cilia, vacuolation of ciliated cells and expansion of intercellular space. These findings show that irradiation-induced otitis media with effusion results in impairment of the mucociliary system. As evidenced by these studies, the mucociliary system in the eustachian tube has an important role in the clearance of fluid produced in the tympanic cavity as well as affording improvement in this disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00464303
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  • 139
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    Relative rates of bromination and chlorination of 4-substituted cyclopentenes in methanol, ethanol and acetic acid (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 26-34 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A set of 4-monosubstituted cyclopentenes, , were synthesized and their relative rates (kX/kH) for bromination and chlorination were determined in methanol, ethanol and acetic acid at 25 °C by competitive method. log(kX/kH) for most of the substituents can be correlated by means of Taft's equation, log(kX/kH) = ρI σI + C. In methanol ρI, Br2 = -2·91, ρI, Cl2 = -0·49, in ethanol ρI, Br2 = -3·07, ρI, Cl2 = -0·70 and in acetic acid ρI, Br2 = -1·64, ρI, Cl2 = -0·65. The presence of C(〈0) is due to a constant steric effect. The deviation of X = H is ascribed to the absence of the steric effect and that of X = CO2Me and CO2Et is accounted for in terms of anchimeric assistance. For chlorination no anchimeric assistance was observed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020104
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  • 140
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    Kinetics and mechanism of the acid-catalyzed hydration of dihydro-1,4-dioxin (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 43-50 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cyclic vinyl ether dihydro-1,4-dioxin is converted to its cyclic hemiacetal hydration product, 2-hydroxy-1,4-dioxane, in aqueous solution by an acid-catalyzed reaction for which kH+ = 1·80 × 10-5 M-1 S-1 at 25°C. This reactivity and the solvent isotope effect kH+/kD+ = 2·2 show that the reaction occurs by rate-determining proton transfer from catalyst to substrate and not by a pre-equilibrium mechanism as recently proposed.2
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020106
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  • 141
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    The cation radical vinylcyclobutane rearrangement (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 57-88 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cation radical vinylcyclobutane (VCB) rearrangement is found to be a reaction of substantial scope, synthetic utility, and exceptional kinetic facility. In conjuction with cation radical cyclobutanation, it constitutes an effective method for net (indirect) Diels-Alder addition to electron rich dienophiles. Reactions can be carried out with either aminium salt or photosensitized electron transfer (PET) initiation and are powerfully facilitated by ionizable substituents such as p-anisyl, phenylthio, and phenoxy at the 2-position of the vinylcyclobutane. The intramolecularity of the reaction is clearly established and in four discrete systems preferred sr (suprafacial/retention) stereochemistry is observed. A theoretical basis for sr stereochemistry in the cation radical VCB rearrangement is advanced. The transition state for the reaction is considered to be similar to that for the direct cation radical Diels-Alder cycloaddition, another cation radical pericyclic reaction which converges on the same product. This model of the VCB rearrangement transition state is used to rationalize the strong rate-retarding effect of a Z-methyl substituent attached to the vinyl group and of a methyl substituent at the 4-position of the vinylcyclobutane ring cis to the vinyl substituent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020108
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  • 142
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    Multifunctional catalysis for transamination reaction of α-amino acids with glyoxylic acid in synthetic bilayer memberane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 110-116 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The transamination reaction of α-amino acids with glyoxylic acid as catalyzed by copper(II) ions was investigated kinetically in an aqueous medium at pH 5·0 and 30·0°C. L-Phenylalanine transferred its amino group to glyoxylic acid most readily among seven different amino acids used here in the single-walled bilayer vesicle formed with N,N-dihexadecyl-Nα-[6-(trimethylammonio)hexanoyl]-L-histidinamide bromide (N+C5His2C16). Such rate enhancement was found to originate from the cooperative trifunctional catalysis: a coordination effect exercised by copper(II) ions, a general acid-base catalysis by the imidazolyl group of the lipid, and a hydrophobic field effect provided by the bilayer vesicle. Lack of any of the three functions failed to give out significant rate enhancement. As regards correlation between the reactivity and the nature of α-amino acids, the copper(II)-catalyzed transamination was progressively enhanced as hydrophobicity of the α-amino acid was increased in the N+C5His2C16 vesicle.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020204
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  • 143
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020301
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  • 144
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    The ‘dimer mechanism’ in aromatic nucleophilic substitution by amines in aprotic solvents (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 1-14 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of aromatic nucleophilic substitutions by amines in protic solvents is well established; on the contrary the mechanism/s of the reactions in aprotic solvents is/are still subject of controversy. The present paper describes several systems for which fourth-order kinetics (third-order in amine) were observed. A mechanism is proposed to account for this as well as other observation such as: overall negative energies of activation, quadratic dependence of kA with non-nucleophilic tertiary bases, spectacular effects of hydrogen-bond donor (HBD) and hydrogen-bond acceptor (HBA) catalysts, etc. Other alternative mechanisms are also discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020102
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  • 145
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    Cross interaction constants as a measure of the transition state structure (part III). Mechanism of reactions between 1-phenylethyl benzenesulfonates with N,N-dimethylanilines (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 35-42 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics and mechanisms of the reactions between 1-phenylethyl benzenesulfonates (1-PEB) with N,N-dimethylanilines are investigated in methanol at 35·0°C. Reactivity and selectivity trends were found to be similar to those for the reactions of 1-PEB with anilines, but the magnitudes of cross interaction constants, ρXZ, between substituents X in the nucleophile and Z in the leaving group were substantially smaller indicating no hydrogen-bond bypass bridge formation in the transition state. However, the magnitude of ρXZ suggested a direct electrostatic interaction between the reaction centers in the nucleophile and leaving group in the frontside nucleophilic attack with a loose transition state structure.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020105
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  • 146
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    Twisted internal charge transfer emission in B,B-bis(mesityl) pyrroloboranes (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 89-92 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spectral characteristics of several simple substituted B,B-bis(mesityl)pyrroloboranes are reported which support a theoretical treatment by Bonacic-Koutecky and Michl (J. Am. Chem. Soc. 107, 1765 (1985)) describing the excited states of simple aminoboranes as an example of twisted internal charge transfer. In the aminoboranes the pyrrolo moiety functions as the electron donor group and the empty p-orbital of the boron atom as the acceptor.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020109
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  • 147
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020201
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  • 148
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    Reassignment of the fundamental vibrations of azetidine from ab initio calculations (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 183-186 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The harmonic vibrational frequencies were calculated analytically at the 6-31** level for azetidine using the GAUSSIAN 82 program. The results strongly indicate the presence of several errors in a recent assignment of the fundamentals of azetidine based on a normal coordinate analysis and a revised assignment is suggested. It is concluded that reliable vibrational data for azetidine in the gas phase are needed in order to resolve the remaining ambiguities in the interpretation of the spectra.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020210
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  • 149
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    Mechanism of the Grignard reaction (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 205-213 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mechanism of the Grignard reactions of aromatic ketones in THF was studied by spectroscopic and kinetic methods. The stable radical intermediates generated in the initial electron transfer from Grignard reagent to ketones are in a state of aggregated dimer of corresponding ion-radical pairs; in which two ketone anion radicals are bridged by a dimer di-cation of Grignard reagent. Subsequent alkyl radical transfer from dimeric Grignard reagent cation moiety to ketone anion radical aggregated each other are promoted by a participation of another neutral Grignard reagent. Proposed mechanism by present authors is able to explain well addition products/reduction products ratios in the Grignard reactions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020303
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  • 150
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    Non-hierarchical classification of organic solvents using characteristic vector analysis of physical and empirical solvent parameters (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 232-242 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Characteristic vector analysis of a set of six physical and empirical parameters of 103 commonly used organic solvents (bp, ∊r, μ, nD, ETN, and δ) gives four vectors describing 95% of the total data variability. Non-hierarchical cluster analysis, applied to our results, leads to ten separate classes of organic solvents.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020306
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  • 151
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    A preliminary quantum-chemical study of the mechanisms for the reactions of perchlorofluoroethanes with nucleophiles initiated by chlorophilic attacks (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 103-109 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A preliminary theoretical study of the mechanisms for the reactions of the perchlorofluoroethanes CF2ClCCl3 (1), CF2ClCCl2F (2) and CF3CCl3 (3), with nucleophiles has been carried out by the MNDO method, following the experimentally suggested process shown in Scheme 1. The unlikely chlorophilic attack in the first step of Scheme 1 has been shown to be feasible for 1, 2 and 3 by analysis of the MO interactions. The second step has been found to be affected by the anionic hyperconjugation which stabilizes the anions CF2ClCCl2- (4), CF2ClCClF- (5) and CF3CCl2- (6) and would make reactions (2) (the second step) unfeasible in gas phase, but in solution reaction (2) may still easily occur for 4 and 5.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020203
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  • 152
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    Studies on organophosphorus compounds XXXII. A molecular mechanics study of the hydrolytic reaction of alkylphosphonates and alkylphosphonyl chlorides (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 146-160 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The alkaline hydrolysis of several alkylphosphonates and alkylphosphonyl chlorides has been investigated by molecular mechanics calculations (MM2, 1985 version). The difference of the steric energies (ΔE) between tetracoordinate substrate and pentacoordinate transition state of phosphorus compounds represents the activation energy (ΔE≠) in hydrolysis. The change of ΔE for various alkyl groups relative to methyl group (ΔΔER) is suggested as a measure of the steric effect of substituents. Thus the correlation analysis involving log k and ΔΔER of the branched alkyl group gives good results and it is reasonable to anticipate that analogous treatment using ΔΔER for the straight chain alkyl group is not satisfactory owing to the minor contribution of steric effect of the latter. However, the multiple regression analysis of log k with ΔΔER and Taft's σ* provides very good results. As shown by us, for the hydrolytic reactions studied, the proposed ΔΔER is much better than Taft's Es and Charton's ν, the commonly used well-known steric parameters in the chemistry of carbon compounds.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020207
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  • 153
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    Theoretical studies of the singlet and triplet potential energy surfaces of cyclobutanediyl (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 161-176 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cyclobutanediyl (2) has been studied in both its singlet and triplet states by ab initio electronic structure theory. The triplet, which is the ground state of the molecule, exists in both C2h and C2v forms which interconvert via a Cs transition state. For the singlet, only a C2h form is found. It passes, via a Cs transition state, onto the C2v surface on which bicyclobutane (3) is the only minimum. The ring-flipping (inversion) process in 3 includes the singlet biradical as an intermediate, and involves a novel, non-least motion path similar to one previously proposed by Gassman. Semiclassical periodic orbit theory indicates that the various minima on both the singlet and triplet surfaces can interconvert via quantum mechanical tunneling.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020208
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  • 154
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    Polyvinyl Alcohol–Methyl Acrylate Copolymers as a Sustained-Release Oral Delivery System (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 844-847 
    Details
    ISSN: 1573-904X
    Keywords: polyvinyl alcohol–methyl acrylate copolymers ; crystalline ; low crystalline ; phenylpropanolamine ; sustained release ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Low crystalline and crystalline polyvinyl alcohol–methyl acrylate (PVA-MA) copolymers were examined, because of their excellent flow and compressibility properties, as matrices for sustained-release tablets using phenylpropanolamine hydrochloride (PPA.HC1) as a model drug. Crystallinity of the copolymer affected the release characteristics from the tablet. Tablets made with low-crystalline PVA-MA provided sustained release of PPA, both in vitro and in vivo in dogs. PPA absorption from the low-crystalline PVA-MA tablet formulation was biphasic. An initial rapid phase was followed by a second, slower absorption phase which continued over 16 hr. Plasma PPA concentrations then declined with a half-life roughly parallel to the oral immediate-release half-lives. Oral bioavailability from the low-crystalline PVA-MA tablet formulation was 78.8 ± 3.9%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015900303534
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  • 155
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    High-Performance Liquid Chromatographic Determination and Pharmacokinetics of Methyl N-[5[[4-(2-Pyridinyl)-l-piperazinyl]carbonyl]-1H-benzimidazol-2-yl] Carbamate (CDRI Compound 81-470), a New Anthelmintic Agent in Rats (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 991-993 
    Details
    ISSN: 1573-904X
    Keywords: CDRI compound 81-470 ; anthelmintic ; high-performance liquid chromatography (HPLC) ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015910000325
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  • 156
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    Effect of the Immunomodulator Tilorone on the in Vivo Acetylation of Procainamide in the Rat (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 477-480 
    Details
    ISSN: 1573-904X
    Keywords: acetylation ; immunomodulators ; interferon inducers ; pharmacokinetics ; procainamide ; tilorone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Interferon and interferon inducers have been found to inhibit cytochrome P-450-dependent metabolism in animals and man. The effect of these agents on the acetylation of drugs has not been previously reported. Since these agents stimulate the reticuloendothelial system, together with the abundance of N-acetyltransferase in the reticuloendothelial system, it was hypothesized that these immunomodulators may affect drug acetylation. To test this hypothesis, the effect of tilorone (a synthetic interferon inducer) on the in vivo acetylation of procainamide was examined in the rat. Pretreatment with tilorone hydrochloride (50 mg/kg) 48 hr prior to the administration of procainamide hydrochloride (50 mg/kg) resulted in a 32% increase in the urinary recovery of N-acetylprocainamide and a 35% increase in the metabolic clearance of procainamide to N-acetylprocainamide. These data indicate that interferon inducers increase the N-acetylation of drugs in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015964306318
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  • 157
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    Liposomal Formulation Eliminates Acute Toxicity and Pump Incompatibility of Parenteral Cyclosporine (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 601-607 
    Details
    ISSN: 1573-904X
    Keywords: liposome ; cyclosporine ; acute toxicity ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The currently available intravenous dosage form of cyclosporine (CSA), Sandimmune I.V., contains the vehicle, Cremophor EL, which has been implicated in producing anaphylactic reactions in man and animals. This formulation also leaches through silicone tubing, an important component of some automatic drug delivery devices, causing pump dysfunction. In an attempt to develop a less toxic and pump-compatible formulation of CSA, suitable for intrarenal infusion in a canine transplant model, we compared the acute toxicity, pharmacokinetics, and pump compatibility of emulsified (CSA/emulsion) and liposomal (CSA/liposomes) CSA preparations with those of Sandimmune I.V. and CSA dissolved in ethanol vehicle (CSA/alcohol) in healthy, unoperated dogs. Animals receiving Sandimmune I.V. demonstrated marked acute toxicity despite progressive 10-fold dose reduction and 〉50-fold prolongation of infusion duration. One of two animals receiving CSA/emulsion and both dogs receiving emulsion vehicle alone exhibited a moderately severe reaction, while five of seven dogs receiving CSA/alcohol demonstrated immediate, mild reactions. No discernible adverse reactions occurred in any animal receiving CSA/liposomes. Systemic disposition of CSA/alcohol and CSA/liposomes was similar. In contrast to the liposomal vehicle, the emulsion vehicle produced a marked, early weight gain and substantial decrease in tensile strength of the pump tubing, both of which would adversely affect pump function. These results provide the first description of liposomal CSA toxicology and pharmacokinetics in a large animal model and may lead to the successful development of a less toxic parenteral CSA formulation for systemic and local pump-based administration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015905615404
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  • 158
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    Route of Administration and Sex Differences in the Pharmacokinetics of Aspirin, Administered as Its Lysine Salt (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 660-666 
    Details
    ISSN: 1573-904X
    Keywords: aspirin ; pharmacokinetics ; intramuscular ; sex differences ; rate of absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract One thousand milligrams of aspirin, as its lysine salt, was administered intravenously, orally, and intramuscularly to nine male and nine female young healthy adult volunteers. After intravenous injection mean (±SD) values of clearance, steady-state volume of distribution, and terminal half-life were 12.2 ± 2.2 ml/min/kg, 0.219 ± 0.042 liter/kg, and 15.4 ± 2.5 min, respectively, with no differences between males and females. Following oral administration aspirin was absorbed more quickly in females than in males (mean absorption times of 16.4 and 21.3 min, respectively) although the bioavailability, 54%, was the same in both groups. In contrast, following intramuscular administration, aspirin was absorbed more slowly in females than males (mean absorption times of 97 and 53 min, respectively) but again the bioavailability, 89%, was the same in both groups. The data suggest that in the female the intramuscular injection is going into fat. Salicylic acid concentration–time profiles showed a less pronounced sex difference and were comparable among the three routes of administration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015978104017
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  • 159
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    Electronic Resource
    Pharmacokinetics of Ketorolac and p-Hydroxyketorolac Following Oral and Intramuscular Administration of Ketorolac Tromethamine (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 62-65 
    Details
    ISSN: 1573-904X
    Keywords: ketorolac ; p-hydroxyketorolac ; oral ; intramuscular ; pharmacokinetics ; dose proportionality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ketorolac tromethamine (KT), a potent analgesic with cyclooxygenase inhibitory activity, was administered in an open, randomized, single-dose study of Latin-square design to 12 healthy male volunteers. Doses of 30 mg oral (po) and 30, 60, and 90 mg intramuscular (im) KT were administered in solution. Plasma samples were analyzed for ketorolac (K) and its inactive metabolite, p-hydroxyketorolac (PHK), by reversed-phase high-performance liquid chromatography (HPLC). The 30-mg im dose was found to be similar to the 30-mg po dose with respect to total AUC values for both K and PHK. The amount of PHK circulating in plasma was very low as judged by AUC ratios (PHK/K × 100) of 1.9 and 1.5% for the 30-mg po and im doses, respectively. The rate of absorption of K and formation of PHK, as determined by C max and T max values, was significantly slower following the im doses. Total AUC and C max for K and PHK increased linearly with dose after im administration of 30, 60, and 90 mg of KT. The mean plasma half-life of K was remarkably consistent between po and im administration and was independent of dose, ranging from 5.21 to 5.56 hr. The plasma metabolic profile was similar following both routes of administration and graded im doses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015803803650
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  • 160
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    Electronic Resource
    Binding of Sulfonamides to Carbonic Anhydrase: Influence on Distribution Within Blood and on Pharmacokinetics (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 203-209 
    Details
    ISSN: 1573-904X
    Keywords: pharmacokinetics ; carbonic anhydrase ; sulfonamides ; binding ; erythrocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Four new aromatic sulfonamides were synthesized and purified by standard techniques. Two were unsubstituted, primary sulfonamides and two possessed substituents on the sulfonamide nitrogen. The affinity of the inhibitors for the enzyme carbonic anhydrase was determined in terms of the inhibitory potency, which was found to be dependent on the presence of an unsubstituted sulfonamide group. Binding studies were performed in erythrocyte suspensions using a range of concentrations and the unbound, extracellular concentrations were determined by high-performance liquid chromatographic (HPLC) assay. The dissociation constant of binding and the total binding capacity of the erythrocytes were estimated by nonlinear regression using a two-site binding model. The affinity of the compounds for erythrocytes reflected their inhibitory potency against the enzyme. Binding to plasma proteins was more dependent on lipophilicity and pK a and was stronger for the substituted sulfonamides. Pharmacokinetic studies in rats showed that the unsubstituted sulfonamides with a high affinity for carbonic anhydrase in erythrocytes have longer half-lives and lower clearance values than the substituted sulfonamides which were more strongly bound to plasma proteins. However, comparison of unbound clearance values showed that the variations in molecular structure, which produced differences in carbonic anhydrase binding and in distribution, also produced variations in susceptibility to elimination processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015957315462
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  • 161
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    Electronic Resource
    Experimental Animal Models for Studying Antimicrobial Pharmacokinetics in Otitis Media (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 279-285 
    Details
    ISSN: 1573-904X
    Keywords: otitis media ; pharmacokinetics ; amoxicillin ; trimethoprim ; sulfamethoxazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Antimicrobial treatment of otitis media, especially drug dosing considerations, is largely empiric, with few reported pharmacologic studies of drug distribution into the middle ear. A chinchilla animal model of serous and purulent otitis media has been used for some time to investigate mechanisms of disease pathogenesis. This model was adapted to investigate the penetration of amoxicillin, trimethoprim, and sulfamethoxazole into middle ear effusion. Purulent otitis media was produced by direct middle ear inoculation with type 7F Streptococcus pneumoniae. Serous otitis media was produced by eustachian tube obstruction using silastic sponge or Coeflex cement, but the Coeflex caused an undesirable local inflammatory response. The three antibiotics were administered to chinchillas with serous and purulent middle ear effusion. Plasma and ear fluid drug concentrations were measured by liquid chromatography and demonstrated the value of this model in assessing antibiotic penetration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015938205892
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  • 162
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    Electronic Resource
    Structure–Pharmacokinetic Relationships in a Series of Valpromide Derivatives with Antiepileptic Activity (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 683-689 
    Details
    ISSN: 1573-904X
    Keywords: valpromide ; valproic acid ; antiepileptic activity ; SAR ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The following valpromide (VPD) derivatives were synthesized and their structure–pharmacokinetic relationships explored: ethylbutylacetamide (EBD), methylpentylacetamide (MPD), propylisopropylacetamide (PID), and propylallylacetamide (PAD). In addition, the anticonvulsant activity of these compounds was evaluated and compared to that of VPD, valnoctamide (VCD), and valproic acid (VPA). MPD, the least-branched compound had the largest clearance and shortest half-life of all the amides investigated and was the least active. All other amides had similar pharmacokinetic parameters. Unlike the other amides, PID and VCD did not metabolize to their respective homologous acids and were the most active compounds. Our study showed that these amides need an unsubstituted β position in their aliphatic side chain in order to biotransform to their homologous acids. An amide which is not metabolized is more potent as an anticonvulsant than its biotransformed isomer. All amides were more active than their respective homologous acids. In this particular series of aliphatic amides, which were derived from short-branched fatty acids, the anticonvulsant activity was affected by the pharmacokinetics in general and by the biotransformation of the amide to its homologous acid in particular. This amide–acid biotransformation appeared to be dependent upon the chemical structure, especially upon the substitution at position β of the molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015934321764
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  • 163
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    Electronic Resource
    Dose-Ranging Pharmacokinetics of Zidovudine (Azidothymidine) in the Rat (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 734-736 
    Details
    ISSN: 1573-904X
    Keywords: dose ranging ; pharmacokinetics ; zidovudine ; azidothymidine ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015954926307
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  • 164
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    Pharmacokinetics of Sulfasalazine Metabolites in Rats Following Concomitant Oral Administration of Riboflavin (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 1067-1072 
    Details
    ISSN: 1573-904X
    Keywords: sulfasalazine ; metabolites ; riboflavin ; azo-reduction ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sulfasalazine, 60 mg/kg, was administered orally to groups of rats (n = 4) along with 1, 5, or 10 mg/kg of riboflavin. Plasma and urine were assayed for 5-aminosalicylic acid, acetyl-5-aminosalicylic acid, sulfapyridine, and acetyl-sulfapyridine using an HPLC method. The mean percent of dose recovered as total metabolites in urine was significantly greater (α = 0.01) for the group receiving 10 mg/kg riboflavin compared to the controls or the group receiving 1 mg/kg riboflavin. Plasma AUC and C max values were also significantly greater (α = 0.05) for the 10 mg/kg riboflavin group. These results suggest that at higher doses, a significant fraction of riboflavin reaches the colon intact and stimulates more efficient reduction of the azo bond in sulfasalazine. Since the concentrations of 5-ASA achieved in the colon may be directly related to the efficacy of sulfasalazine in treating inflammatory bowel disease, concomitant administration of riboflavin may enhance sulfasalazine's efficacy in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015938706685
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  • 165
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    Electronic Resource
    Prediction of the Distribution Volumes of Cefazolin and Tobramycin in Obese Children Based on Physiological Pharmacokinetic Concepts (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 486-491 
    Details
    ISSN: 1573-904X
    Keywords: cefazolin ; tobramycin ; volume of distribution ; pharmacokinetics ; intravenous administration ; obese children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract So as to estimate the appropriate dose of antibacterial drugs in obese children, prediction of the volume of distribution in these children was attempted based on physiological pharmacokinetic concepts which had been constructed from results in normal-weight children. Serum concentration–time data after intravenous drip infusions of tobramycin and cefazolin were analyzed using noncompartmental analysis of obese children in whom the degree of obesity ranged from 30 to 80%. Volume of distribution at steady state (V ss) per total body weight of tobramycin was significantly less than that for normal-weight children (P 〈 0.05), whereas the value of cefazolin was almost equal to that for normal-weight children. The equation to express the difference of Vss between cefazolin and tobramycin obtained in normal-weight children failed in obese children, suggesting that there is a large decrease in the extracellular space in obese children exceeding the interindividual variations in normal-weight children. The V ss value (liter) for tobramycin was predicted by using the equation 0.261 · {ideal body weight (kg) + 0.4 · [total body weight (kg) – ideal body weight (kg)]}. The V ss value of cefazolin was predicted to be 0.3 · (predicted V ss of tobramycin) + 0.052 · total body weight (kg). A good correlation between the predicted and the observed V ss values was obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015968407226
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  • 166
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    Electronic Resource
    Efficiency of Drug Targeting: Steady-State Considerations Using a Three-Compartment Model (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 367-372 
    Details
    ISSN: 1573-904X
    Keywords: drug targeting ; site-specific delivery ; steady state ; pharmacokinetics ; pharmacodynamic model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Physiological models have often been used to investigate the processes involved in drug targeting. Such a model is used to investigate some aspects of drug targeting, including the pharmacodynamics of therapeutic and toxic effects. A simple pharmacodynamic model is incorporated in a three-compartment pharmacokinetic model. Conventional administration and drug targeting are compared at steady state for the same degree of therapeutic effect. The efficiency of drug targeting is quantified as the ratio (TA) of the rates of administration of free drug or of a drug–carrier complex required to achieve this effect. Also, the ratios of drug concentrations in the toxicity compartment (DTI) or of the consequent degree of toxic effects (TI) are used to compare conventional administration with drug targeting. The kinetic characteristics of the drug–carrier complex, rate of elimination, and rate of free drug release, influence TA but not DTI or TI. The importance of these characteristics depends on the cost and toxicity of the drug–carrier complex or of the carrier alone. The pharmacodynamics of the free drug in both the target and the toxicity compartments have an important influence on TI but not on TA or DTI. As the pharmacological selectivity of the drug increases, so does TI. However, a drug with good pharmacological selectivity may not be suitable for drug targeting. TI is also very dependent on the shape of the effect–concentration curves, particularly that for toxicity. While TA increases as the rate of elimination of free drug from either central or target compartments increases, TI may actually be reduced if release of free drug is not confined to the target compartment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015971113161
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  • 167
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    Electronic Resource
    Pharmacokinetics and Oral Bioavailability of Scopolamine in Normal Subjects (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 481-485 
    Details
    ISSN: 1573-904X
    Keywords: pharmacokinetics ; scopolamine ; drug disposition ; motion sickness drug
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and bioavailability of scopolamine were evaluated in six healthy male subjects receiving 0.4 mg of the drug by either oral or intravenous administration. Plasma and urine samples were analyzed using a radioreceptor binding assay. After iv administration, scopolamine concentrations in the plasma declined in a biexponential fashion, with a rapid distribution phase and a comparatively slow elimination phase. Mean and SE values for volume of distribution, systemic clearance, and renal clearance were 1.4 ± 0.3 liters/kg, 65.3 ± 5.2 liters/hr, and 4.2 ± 1.4 liters/hr, respectively. Mean peak plasma concentrations were 2909.8 ± 240.9 pg/ml following iv administration and 528.6 ± 109.4 pg/ml following oral administration. Elimination half-life of the drug was 4.5 ± 1.7 hr. Bioavailability of the oral dose was variable among subjects, ranging between 10.7 and 48.2%. The variability in absorption and poor bioavailability of oral scopolamine indicate that this route of administration may not be reliable and effective.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015916423156
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  • 168
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    Electronic Resource
    Pharmacokinetics of Platinum in Cancer Patients Treated with Carboplatin in Combination with High-Dose Methotrexate (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 492-496 
    Details
    ISSN: 1573-904X
    Keywords: carboplatin ; pharmacokinetics ; platinum, total, ultrafilterable ; urinary excretion ; cancer patients ; chemotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics of platinum was investigated in 10 cancer patients treated with a 1-hr infusion of 300 mg/m2 of carboplatin which was given 2–4 days after the administration of 100 mg/kg (20-mg/kg bolus and 80-mg/kg intravenous infusion) of methotrexate. Platinum was analyzed in the samples by flameless atomic absorption spectrophotometry. The concentration vs time data for total platinum in plasma followed a two-compartment model and the mean (and SE) values for β, TBC, V c, and RC were 0.0827 (0.22) hr−1, 2.355 (0.252) liters/hr · m2, 10.74 (0.62) liters/m2, and 2.405 (0.228) liters/hr · m2, respectively. There was no significant change in the creatinine clearance or TBC with repeated treatment. The ultrafilterable platinum which was measured in the plasma of two patients constituted 82 and 11.3% of the total platinum at 1 and 24 hr, respectively, and the data conformed to the one-compartment model. The mean (SE) values for t β, TBC, and V d for free platinum were 1.844 (0.208) hr, 4.583 (1.059) liters/hr · m2, and 11.88 (1.45) liters/m2, respectively. The above data are in good agreement with those reported earlier for platinum following the administration of carboplatin as a single agent. These results suggest that high-dose methotrexate therapy, when administered 2–4 days before carboplatin, does not affect the pharmacokinetics of platinum in the plasma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015920524065
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  • 169
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    Electronic Resource
    The Effect of End-to-Side Portacaval Shunt on Cyclosporine Pharmacokinetics in Rats (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 255-257 
    Details
    ISSN: 1573-904X
    Keywords: cyclosporine ; pharmacokinetics ; rats ; portacaval shunt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015977820005
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  • 170
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    A Retrospective Analysis of Fenoldopam Renal Excretion in 65 Subjects: Evidence for Possible Intrarenal Formation of Fenoldopam from Its Metabolites (1989)
    Springer
    Pharmaceutical research 6 (1989), S. 702-705 
    Details
    ISSN: 1573-904X
    Keywords: fenoldopam ; renal excretion ; reversible metabolism ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Clinical studies have suggested that the dopamine DA1 agonist, fenoldopam, may exhibit nonlinear renal excretion in humans. A retrospective population pharmacokinetic analysis of the renal excretion of fenoldopam and one of its major metabolites, fenoldopam-8-sulfate, was conducted in 65 healthy volunteers to examine this phenomenon. Fenoldopam-8-sulfate exhibited a mean (±SE) renal plasma clearance of 129 ± 4 ml/min, which was independent of its AUC. In contrast, fenoldopam renal plasma clearance ranged from 2220 to 150 ml/min and decreased nonlinearily with increasing fenoldopam AUC. Fenoldopam renal clearance was characterized as a function of fenoldopam AUC using a nonlinear saturation model. The analysis predicted an initial maximal renal clearance of 2852 ml/min, which decreased to 78 ml/min at maximal inhibition. The fenoldopam AUC required to half-saturate fenoldopam renal clearance was 5.2 ng × hr/ml. The elevated clearance values for fenoldopam, beyond normal physiologic limits for renal blood flow in man, suggest that intrarenal formation of fenoldopam from one or more of its circulating metabolites may be contributing to the observed nonlinear decreases in fenoldopam renal excretion. Preliminary data from our laboratory suggest that in vivo desulfation of fenoldopam-8-sulfate to fenoldopam does occur in the dog.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015990506743
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  • 171
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    Electronic Resource
    Current models in pharmacokinetics: Applications in veterinary pharmacology (1989)
    Springer
    Veterinary research communications 13 (1989), S. 141-157 
    Details
    ISSN: 1573-7446
    Keywords: models ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Major advances in developing models for pharmacokinetic studies have been made in recent years, and different approaches can now be employed. These include the use of (1) compartmental models, (2) non-compartmental models, (3) physiological models, (4) population pharmacokinetic models, and (5) pharmacokinetic-pharmacodynamic models. Each of these approaches has both advantages and disadvantages. The important question of which of these is ‘ideal’ in veterinary pharmacokinetics has no simple answer. The selection and application of any one approach would depend on a number of factors, such as (1) the purpose of the study, (2) physicochemical properties and actions of drug, (3) specificity and sensitivity of the analytical methodology, (4) species of the animal, and (5) availability of funds. This paper reviews the models available for pharmacokinetic studies and indicates their possible application in veterinary pharmacology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346724
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  • 172
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    Electronic Resource
    Disposition and dosage regimen of cephaloridine in calves (1989)
    Springer
    Veterinary research communications 13 (1989), S. 325-329 
    Details
    ISSN: 1573-7446
    Keywords: blood ; cattle ; cephaloridine ; chemotherapy ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The disposition and dosage regimen of cephaloridine were investigated in healthy calves following a single intramuscular administration of 10 mg/kg. The absorption halflife, climination halflife, apparent volume of distribution and total body clearance were 0.107±0.025 h, 2.08±0.14 h, 0.70±0.07L kg-1 and 235.8±21.9 ml kg-1 h-1, respectively. Therapeutic plasma levels (≥1 μg/ml) were maintained for up to 7 h. A satisfactory intramuscular dosage regimen for cephaloridine in calves would be 10 mg/kg repeated at 8 h intervals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00420839
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  • 173
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    Disposition kinetics and urinary excretion of gentamicin in buffalo bulls (Bubalus bubalis) (1989)
    Springer
    Veterinary research communications 13 (1989), S. 331-337 
    Details
    ISSN: 1573-7446
    Keywords: blood ; buffalo ; chemotherapy ; gentamicin ; pharmacokinetics ; urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The disposition kinetics and urinary excretion of gentamicin sulphate were studied in young buffalo bulls following a single intramuscular administration of the drug at 5 mg kg-1 body weight. The time course of the serum gentamicin concentration was adequately described by the one-compartment open model. The values of the absorption and elimination halflives were 12.2±2.2 and 167.0±29.7 min respectively. The apparent volume of distribution was 0.29±0.01 L kg-1. During the first 12 h, 63% of the total administered dose was excreted in urine. On the basis of the kinetic data, a satisfactory intramuscular dosage regimen for gentamicin sulphate would be at least 6 mg kg-1 body weight repeated at 8 h intervals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00420840
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  • 174
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    Disposition of125I-labeled recombinant human tumor necrosis factor in the tumor-bearing mouse (1989)
    Springer
    Biotherapy 1 (1989), S. 7-18 
    Details
    ISSN: 1573-8280
    Keywords: disposition ; distribution ; excretion ; Meth A sarcoma ; pharmacokinetics ; tumornecrosis factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Disposition of [125I]rHu-TNF was elucidated in BALB/c mice bearing Meth A fibrosarcoma 7 days after transplantation. Afteri.v. administration, [125I]rHu-TNF measured by radioactivity and immunoreactivity biphasically decreased in plasma. Tumor level of [125I]rHu-TNF was the maximum at 1 h, then decreased and finally remained essentially constant. After i.t. administration, plasma level reached the maximum at 1 h. Tumor level decreased quickly and then became essentially constant. [125I]rHu-TNF was suggested to be degraded to small fragments in the tumor. Significant distribution of [125I]rHu-TNF was found in the kidney, lung, liver and tumor. Most tissue levels decreased with time in parallel with plasma levels. [125I]rHu-TNF radioactivity was found in proximal convoluted tubules of kidney and in those areas of tumor consisting of degenerating cells with pyknotic nuclei. Urine contained most of administered radioactivity, which being neither immunoreactive nor protein-bound.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02170131
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  • 175
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020101
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  • 176
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    Ion pairs in solvolysis reactions. Kinetic deuterium isotope effects for deprotonation of carbocation intermediates in aqueous solvent (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 15-25 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solvolysis of 2-X-2-phenylpropane (1-X) in 25 vol% acetonitrile in water at 25°C produces 2-hydroxy-2-phenylpropane (1-OH) and 2-phenylpropene (3). The carbocationic intermediate discriminates between different nucleophiles; azide anion, acetate anion, and methanol are more efficient nucleophiles than water, kN3/kH2O = 42 kOAc/kH2O = 3, and kMeOH/kH2O = 2·9 (ratio of second-order rate constants). The fraction of the elimination product 3 increases with increasing basicity of the leaving group X as well as by addition of general bases. The Brønsted parameter for this catalysis is small, β = 0·13, with substituted acetate anions. The kinetic deuterium isotope effect for the dehydronation of the intermediate has been measured (assuming the reaction from intermediate to alcohol is insensitive to isotopic substitution) employing the hexadeuterated substrate d6-1-X as k3H/k3d6 = 3·5 ± 0·2 for the chloride 1-Cl with acetate anion, and, without added base, 3·1 ± 0·2 for the acetate 1-OAc, and 3·1 ± 0·2 for the p-nitrobnzoate 1-PNB, respectively, and ∼5 for the protonated methyl ether 1-OMeH+. The variation in isotope effect with change in leaving group is discussed in terms of elimination from contact ion pairs and ‘free’ carbocation. The overall kinetic isotope effect for the solvolysis was found to be kobsH/kobsd6 = 1·31 (1-OMeH+), 1·38 (1-OAc), 1·40 (1-PNB), and 5·7 (1-OH2+). These isotope effects consist of the isotope effect k12H/k12d6 for the formation of the substitution product 1-OH and k13H/k13d6 for production of the olefin 3. It is concluded that the latter isotope effect is enlarged owing to a branched mechanism in which the deprotonation of the carbocationic intermediate competes with formation of the substitution product. As large an isotope effect as k13H/k13d6 ∼6·5 has been measured for 1-OMeH+.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020103
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  • 177
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    The use of IR spectroscopy to monitor the conversion of matrix isolated phenylacetyl chloride to phenylacetyl cation, without decarbonylation to benzyl cation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 51-56 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: IR spectroscopy is presented as a convenient means to monitor the formation of acyl (and alkyl) cations from corresponding acid chlorides, with Lewis acids at low temperature in the solid state. Phenylacetyl chloride is co-deposited (under vacuum at -173°C with antimony pentafluoride on a KBr window), as in the ‘molecular beam’ method of cation generation. The initial IR spectrum of the deposition shows (in addition to starting materials) that a small amount of phenylacetyl cation (2274 cm-1) has been formed. Warming the solid matrix to -123°C Promotes the smooth conversion of acid chloride to acyl cation. Ultraviolet irradiation (through quartz windows) at -123°C to -73°C facilitates this conversion but does not result in the loss of carbon monoxide from the acyl cation to form benzyl cation. When benzyl chloride is used in place of phenylacetyl chloride, there is no noticeable difference between IR spectra taken before and after warming and/or photolysis of the solid deposition.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020107
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  • 178
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    Selective 1,2-addition of organocerium(III) reagents to α,β-unsaturated carbonyl compounds (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 93-102 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Organocerium(III) reagents reacted with α,β-unsaturated carbonyl compounds to give 1, 2-addition products (allylic alcohols) in good to high yields. The reaction was studied from a mechanistic point of view by the use of (E)- and (Z)-1-(4′-methoxyphenyl)-3-phenyl-2-propen-1-ones and 4,4-ethylenedioxy-2,6-dimethyl-2,5-cyclohexadienone as the probe compounds. A polar pathway was suggested for the reaction with the former enones. On the other hand, the operability of single electron transfer processes was demonstrated in the reaction with the latter probe compound.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020202
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  • 179
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    Formation of 1:1 adducts between bis(1,2-diaryl-1,2-ethylenedithiolato)metal(0) (metal = NI, PD, and PT) and quadricyclane and their photodissociation (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 131-145 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Bis(1,2-diaryl-1,2-ethylenedithiolato)metal(0) complexes (1; metal = Ni, Pd, and Pt) react with quadricyclane (Q) to give selectively 1:1 adducts which are identical with the adducts between 1 and norbornadiene (NBD). In the adducts, two sulfur atoms of the different dithiolato ligands are added to one of the double bonds of NBD. The reactions of 1 with Q are 103-104 times faster than those with NBD. The more electropositive dithiolatometal complexes react faster with Q and NBD. The adducts are dissociated to the free dithiolatometal complexes and NBD by UV-irradiation (254-436 nm). Upon irradiation with 254 nm light, the photodissociation occurs before the decomposition of the dithiolatometal complexes.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020206
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  • 180
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    Gas phase reactivities of isomeric ions: Methylenediphenylcyclopropane and diphenylmethylenecyclopropane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 117-130 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Gas phase ion/molecule reactions have been used to probe the structure of ions obtained by electron impact upon 1-(diphenylmethylene)cyclopropane and 2,2-diphenyl-1-methylenecyclopropane. The resulting ions of molecular composition C16H14 (m/z 206+) were reacted with charge transfer reagents (6·9 〈 IP 〈 8·8eV), giving evidence for the presence of isomeric ions with different reactivities. The less reactive ion is identified as a trimethylenemethane species (TMM+) in which one cyclopropane bond is broken; the more reactive ions are assigned as vertical ions in which the cyclopropane ring is unaffected. The vertical ions have recombination energies of 8·44 ± 0·05eV, whereas TMM+ has one of 7·41±0·05eV. The TMM+ fraction is not constant; it increases with increasing IP of the reagent. This is attributed to a reagent-catalyzed isomerization of the vertical ion to TMM+. In addition, the reagent ions are observed to undergo a unique reaction with the neutral methylenecyclopropane derivatives: electron transfer and ring opening to yield TMM+. These findings limit the application of the customary equilibrium measurements as a method to determine the substrate IP.
    Additional Material: 7 Ill.
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  • 181
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    General base catalysis of photo-smiles rearrangement of 1-(4-nitrophenoxy)-2-anilinoethane in aqueous solution. Identity of the proton-donating intermediate (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 177-182 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 4-O2NC6H4OCH2CH2NHPh undergoes clean base-catalyzed Smiles photorearrangement to 4-O2NC6H4N(Ph)CH2CH2OH in dimethyl sulfoxide-water (25:75). A linear plot of φ-1 vs [OH-]-1 indicated that the limiting quantum yield at high [OH-] is 0·12 and that uncatalyzed photorearrangement does not occur. Rate constants for the deprotonation step were determined for a variety of bases having conjugate acid pKa values in the range 5-10. When plotted according to the Brønsted Catalysis Law, these data gave a non-linear plot approaching slopes of zero and unity above and below a pKa of 6-7. This indicates that the proton-donating intermediate in this photo-Smiles rearrangement is the zwitterion diradical (pKa ≈ 7) rather than the Meisenheimer complex (pKa ≈ 2).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020209
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  • 182
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    Theoretical study of pyrazole elimination of N-alkyl pyrazoles (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 225-231 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The gas-phase pyrazole elimination of N-alkyl pyrazoles has been studied using MNDO semi-empirical molecular orbital (MO) theory with complete geometry optimization of all stationary points. We found that the activation energies (Ea) of the concerted processes are around 80 kcal/mol, 25 Kcal/mol higher than experimental values. But the differences in Ea between compounds with different substituents are in good agreement with the experimental ones.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020305
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  • 183
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    Photostimulated reactions of neopentyl halides with nucleophiles by the SRN1 mechanism (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 255-262 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photostimulated reaction of neopentyl halides with different nucleophiles by the SRN1 mechanism of nucleophilic substitution has been studied. Neopentyl halides do not react with carbon nucleophiles, diethylphosphite, diphenylphosphonite and azide ions, but they react with arsenide and selenide ions. The photostimulated reaction of neopentyl bromide with diphenylarsenide ions gave only the straightforward substitution product neopentyldiphenylarsine. On the other hand, the photostimulated reaction of bromobenzene with dineopentyl arsenide ions gave three arsines: dineopentylphenylarsine, neopentyldiphenylarsine and triphenylarsine. Neopentyl chloride reacts under irradiation with diphenylphosphide ions giving good yields of the substitution product.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020308
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020401
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  • 185
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    Crystal and molecular structures of dimesitylketene and bis(3,5-dibromo-2,4,6-trimethylphenyl)ketene. Intrinsic torsional angles and buttressing effects in 1,1-dimesitylvinyl propellers (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 271-280 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystal and molecular structures of dimesitylketene (1) and bis(3,5-dibromo-2,4,6-trimethylphenyl)ketene (2), the first free ketenes to be studied by X-ray diffraction, have been determined. The molecules of 1 and 2 have crystallographic C1 and C2 symmetry, respectively, and exist in a propeller conformation. Molecular mechanics calculations of 1 and 2 using a modification of Allinger's new allene parameters reproduce satisfactorily the structural parameters of the ketenes. The torsional angles of the aryl rings in 1 and 2 are similar (ca. 50°) and are regarded as ‘intrinsic’ values for a 1,1-dimesitylvinyl propeller. From the similarity in aryl torsional angles in 1 and 2 it is concluded that the buttressing effects in 2 (if any) are not markedly manifested in the structural parameters of 2.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020310
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  • 186
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    Laser flash photolysis of a chromium carbene complex: Pentacarbonyl(1,3-dimethyl-4-imidazolin-2-ylidene)chromium(0) (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 323-330 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photoreactions of Cr(CO)5(Im) (Im = 1,3-dimethyl-4-imidazolin-2-ylidene) have been investigated by laser flash and continuous photolysis. Quantum yields for the disappearance of Cr(CO)5(Im) in benzene under Ar or CO were very low, although transients observed by laser flash photolysis reacted rapidly with CO. This suggests that photodissociation of the carbene ligand is very minor. The laser flash photolysis at 337 nm in benzene (B) gave a transient (λmax = 630 nm), which converted to the second transient (λmax = 455 nm) within ∼100 ns. The kinetic studies of these transients revealed that the first one is a ‘free’ coordinatively unsaturated species (Cr(CO)4(Im)) and the second one carries a solvent molecule as a ligand (Cr(CO)4(Im)(B)). From the comparison of Cr(CO)4(Im) and Cr(CO)5, apparently lower reactivity of Cr(CO)5 was found to be due to the strong coordination of a solvent molecule. The Im ligand neutralizes the deficit of electron density on Cr. A simple synthesis of Cr(CO)5(Im) was also described.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020404
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  • 187
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    A mechanistic study of the selenium-catalysed carbonylation of secondary amines with carbon monoxide (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 359-362 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction pathway of urea formation by selenium-catalysed carbonylation of secondary amines with carbon monoxide in the presence of oxygen was studied using piperidine as a secondary amine. It was established that selenium reacts with carbon monoxide and piperidine to give carbamoselenoate as an intermediate, which affords biscarbamoyl diselenide by the oxidation with molecular oxygen. Aminolysis of biscarbamoyl diselenide gives the urea derivative, accompanying the regeneration of selenium catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020407
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  • 188
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    Alkylating properties of phosphate esters. 4. Medium effects on methylation of pyridines by trimethyl phosphate (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 377-382 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rates of N-methylation of pyridine and its ring-substituted derivatives by trimethyl phosphate were measured in D2O and in CDCl3. Relative rates, together with the solvent activity coefficients of substrates for the transfer form chloroform to water, were used for determining the solvent activity coefficients of the activated complexes for this SN2 reaction. The results indicate early activated complexes for all pyridines, with the most nucleophilic substrate showing the most reactant-like activated complex.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020503
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  • 189
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    Experimental determination of carbon vs. oxygen regioselectivity in reactions of gas-phase enolate ions (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 389-409 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A gas-phase experimental investigation of the competition between carbon and oxygen alkylation of a series of cyclic and acyclic enolate ions is described. Perfluoropropylene is shown to react in a characteristic way with oxyanions and carbanions to produce distinctive ionic products. The relative yields of these products formed in reactions with ambident enolate ions provides a measure of their intrinsic carbon vs. oxygen regioselectivity. The results for a series of enolates derived from aldehydes, ketones, esters, amides and related compounds show a wide range of reactivity which is a function of the nature of the central substituent. Most aldehyde and ketone enolates react mainly through oxygen, while enolates with σ-acceptor of π-donor type central substituents react mainly thorugh carbon. Ring-size in cyclic ketone enolates also influences C vs. O regioselectivity, i.e. small-ring enolates react mainly through carbon, while larger ring enolates (C7-C9) react preferentially through oxygen. The enolate reactivity patterns can be generally accounted for by the keto-enol energy differences for the parent carbonyl compounds, although some exceptions are evident. The origins of the highly variable, kinetically determined regioselectivities are discussed.
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    URL: http://dx.doi.org/10.1002/poc.610020505
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  • 190
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    ESCA studies of carbanionic compounds: Butyllithium in heptane solution and dibutylmercury in the gas phase (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 417-424 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two organometallic reagents, butyllithium in heptane solution and dibutylmercury in the gas phase, have been studied by means of core electron spectroscopy. The property of particular interest was the charge polarization as reflected by the ESCA shifts. In the butyllithium compound the C1s binding energy is shifted to a lower value by 1·8 eV for C-1 (situated closest to the Li+ ion) relative to the heptane solvent carbon. This is due to the anionic character of the C-1. The interpretation of the experiments was supported by comparing the results with ab initio calculations made on geometry-optimized butyllithium, butyl anion and butane.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020507
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  • 191
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    Dynamic isotope dilution kinetic study of the thermal conversions of bicyclo[3.2.0]hept-2-ene to bicyclo[2.2.1]hept-2-ene and to cyclopentadiene and ethene (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 455-466 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mixtures of bicyclo[3.2.0]hept-2-ene and bicyclo[2.2.1]hept-2-ene, with one isomer labeled with two deuterium atoms, were isomerized in the gas phase at 276 °C. By following the concentration ratios of d0 and d2 versions of bicyclo[2.2.1]hept-2-ene as functions of time one finds that the partitioning of bicyclo[3.2.0]hept-2-ene between the primary products bicyclo[2.2.1]hept-2-ene and cyclopentadiene plus ethene is 2:1. This and earlier stereochemical results permit the calculation of the partitioning of the [3.2.0] olefin between the orbital symmetry allowed [1,3] carbon shift-with-inversion product and several forbidden or non-concerted reaction channels (approximately 1:1) and the stereochemistry of the ethene d2 formed from exo,exo-[6,7-2H2]bicyclo[3.2.0]hept-2-ene directly (1:1 E: Z).
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020604
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  • 192
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020701
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  • 193
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    Reflections on the π-complex theory of benzidine rearrangementsDedicated, with respect, for the 70th birthday of Professor Michael Dewar, who, on scribbled, lunch-time table napkins at the 1961 American Chemical Society meeting in Chicago tried but (fortunately) failed to convince me of the validity of his π-complex theory. I wish I had kept the napkins. (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 491-506 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ups and downs, and reasons therein, of the π-complex theory of the mechanism of the benzidine rearrangements, and the possible role of π-complexes in a newer understanding of the rearrangements, are described.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020702
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  • 194
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    Hydrogen-bonding. Part 4. An analysis of solute hydrogen-bond basicity, in terms of complexation constants (log K), using F1 and F2 factors, the principal components of different kinds of basicityPart 3. M. H. Abraham, P. P. Duce, D. V. Prior, R. A. Schulz, J. J. Morris and P. J. Taylor, J. Chem. Soc. Faraday Trans. 1, 84, 865 (1988). (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 243-254 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The principal components factors F1 and F2 in the equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \log K = {\rm BDP}_0 + S_1 F_1 + S_2 F_2 $$\end{document} have been used to obtain S1 and S2 values for sets of hydrogen-bond bases against 32 reference acid/solvent systems. The constants S1 and S2 define an angle θ = tan-1 S2/S1 that is a measure of the electrostatic:covalent bonding ratio in the hydrogen-bond complex. It is shown that θ can vary from 53 (4-fluorophenol in CH2Cl2)to 86 degrees (Ph2NH in CCl4) depending on the reference acid and solvent. This variation in θ can lead to family dependent behaviour in plots of log K for bases against a given reference acid system vs log K for bases against another reference acid system, and precludes the construction of any general scale of hydrogen-bond basicity using log K values. Amongst a quite wide range of reference acid/solvent systems θ varies only from 64 to 73 degrees, and for bases against these reference systems a ‘reasonably general’ scale could be set up. Such a scale could be extended to bases against reference acid/solvent systems outside the 64-73 degree range provided that certain classes of base (e.g. pyridines, alkylamines) were excluded from the additional reference acid/solvent systems.
    Additional Material: 6 Tab.
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    URL: http://dx.doi.org/10.1002/poc.610020307
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  • 195
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    Application of Marcus theory to photochemical proton transfer reactions. II. Modifications based on intersecting state models (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 300-322 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Various modifications of the Marcus equation have been applied to the problem of photochemical proton transfer, using available data on general acid-catalyzed photohydration reactions. These include incorporation of asymmetry and tightness parameters, as well as distance variation as a function of exoor endothermicity. The intersecting state model of Formosinho has also been successfully applied to these reactions. The overall conclusion from all of these approaches is that the reactions are characterized by somewhat asymmetric and ‘loose’ transition states, with a small but significant degree of charge development on the in-flight proton at the transition state. Estimates of the intrinsic barriers and work terms place these in the 5-7 kcal and 2-3 kcal ranges respectively. A simple valence bond configuration mixing model leads to similar qualitative conclusions about the nature of the transition states in these reactions.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/poc.610020403
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  • 196
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    A theoretical and experimental investigation of acid catalyzed rearrangements of small [n]cyclophanes (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 331-348 
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    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The difference in reactivity of small [n]cyclophanes towards CF3CO2H is discussed in terms of charge densities, strain energies and proton affinities. These data are calculated with MNDO and MINDO/3 for para-, meta- and ortho-cyclophanes and for their ipso-protonation products; an attempt is made to transform gas phase ΔHf0 values into liquid phase ΔH0f values. Experimental evidence is presented that the acid catalyzed rearrangement of [5]paracyclophane to its ortho-isomer proceeds via two consecutive 1,2-carbon shifts without deprotonation; intermediate adducts were identified by NMR-spectroscopy. Thus, a gradual shift in reaction pattern in the series [4]-, [5]- and [6]paracyclophane is observed experimentally, in line with the calculational results.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020405
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    Masthead (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989) 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020501
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  • 198
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    Free-radical reactions of cyclic ethers and sulfides with bromotrichloromethane (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 367-376 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relative rates of hydrogen atom abstraction from a series of twelve saturated cyclic ethers and sulfides were determined at 70°C. The abstracting radical could be generated from bromotrichloromethane both photolytically or by the thermal decomposition of AIBN. The reaction rates did not show a dependence upon method of radical generation. Reaction occurred only at the position adjacent to the heteroatom. The reactivity of the cyclic ethers was in the order C4H8O 〉 C6H12O 〉 C3H6O 〉 C5H10O. This trend would indicate appreciable influence by ring strain, however, the slightly greater reactivity of tetrahydrofuran relative to oxepane suggests a contribution by stereoelectronic factors as well. The reactivity of the cyclic sulfides, which reacted faster than the corresponding ethers, was in the order C4H8S 〉 C5H10S 〉 C6H12S. This would imply little influence of ring strain. The major structural effect would be that of variable electron donating ability of the sulfur atom. The rate of reaction of thietane was also determined. It was found to preferentially undergo SH2 attack at the sulfur atom followed by ring opening rather than hydrogen abstraction. The reactivities of both series of compounds were decreased by the inductive effect of a second heteroatom beta to the reaciton site.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020502
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  • 199
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    Group transfers 4. Arylselenide aniondiaryl diselenide exchange (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 410-416 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Barriers for group transfers between nucleophiles have been postulated to be lowered when the transferring group can carry a considerable negative charge. Furthermore, anions readily subject to one electron oxidation appear to lead to lower barriers than do those of high oxidation potential. These suggestions are pursued here on the identity reaction ArSe- + ArSeSeAr → ArSeSeAr + ArSe-. Indeed the reaction is very fast, as shown by the appearance of only a single peak in the 77Se-NMR in an acetonitrile solution containing both ArSeNa and ArSeSeAr. The rate constant can be only very roughly estimated at low temperatures and dilute solutions, and is likely diffusion controlled for Ar = phenyl and p-methoxyphenyl. A stable intermediate (ArSe)3-, analogous to Br3-, is indicated, but quantitative stability could not be determined, from either the NMR or the UV spectra. Some properties of 77Se-NMR are discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020506
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  • 200
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    Lack of protonation of benzene and toluene by trifluoromethanesulfonic acid and its significance for evaluating superacid strengths (1989)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 2 (1989), S. 425-427 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Distribution between pentane and trifluoromethanesulfonic acid (TFMSA) and carbon-13 NMR measurements showed that benzene and toluene are not protonated to any significant extent in TFMSA. This finding contradicts previous reports, and validates the ranking of superacids based on the extent of benzene protonation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610020508
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