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  • bioavailability  (28)
  • Calcium  (27)
  • Column liquid chromatography  (26)
  • Springer  (81)
  • Alfred Wegener Institute for Polar and Marine Research & German Society of Polar Research
  • Blackwell Publishing Ltd
  • 1980-1984  (81)
  • 1950-1954
  • 1920-1924
  • 1984  (81)
Collection
Keywords
Publisher
  • Springer  (81)
  • Alfred Wegener Institute for Polar and Marine Research & German Society of Polar Research
  • Blackwell Publishing Ltd
  • Wiley-Blackwell  (1)
Years
  • 1980-1984  (81)
  • 1950-1954
  • 1920-1924
Year
  • 1
    Electronic Resource
    Electronic Resource
    Effects of weight loss on serum 1,25-(OH)2-vitamin D concentrations in adults: A preliminary report (1984)
    Springer
    Calcified tissue international 36 (1984), S. 139-144 
    Details
    ISSN: 1432-0827
    Keywords: 1,25(OH)2-vitamin D ; Weight loss ; Phosphate ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary During a review of 42 metabolic studies in healthy women and men we observed that serum 1,25-(OH)2-D concentrations were directly correlated to the observed daily changes in body weight (r=0.68;P〈0.001) and to caloric intake/kg/day (r=0.39;P=0.01). These relationships could not be accounted for by related and physiologically expected changes in serum Ca or iPTH concentrations. However, serum 1,25-(OH)2-D concentrations were observed to be inversely correlated to serum PO4 levels (r=−0.44;P=0.004). In addition, serum PO4 levels were inversely correlated to the daily changes in body weight (r=−0.40;P=0.009). Since dietary sodium intake averaged 142 mmol/day, it is unlikely that the observed changes in weight were the result of changes in salt and water balance. Thus it seems reasonable to speculate that serum 1,25-(OH)2-D concentrations may vary directly with energy balance, as reflected by changes in body weight. This effect may be mediated by alterations in PO4 metabolism. The accurate assessment of serum 1,25-(OH)2-D levels thus appears to require several measurements over time periods during which body weight is stable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405309
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  • 2
    Electronic Resource
    Electronic Resource
    Electromagnetic modulation of biological processes: Influence of culture media and significance of methodology in the Ca-uptake by embryonal chick tibiain vitro (1984)
    Springer
    Calcified tissue international 36 (1984), S. 167-174 
    Details
    ISSN: 1432-0827
    Keywords: Electromagnetic field ; Bicarbonate ; Phosphate ; Calcium ; Fluoride ; Osteogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The present studies are aimed at establishing molecular correlations in the interaction of very low frequency electromagnetic fields with biological systems. Ca-uptake by chick embryo tibia rudiment in short-term culture was a useful model. Tibiae of 8- to 10-day-old chick embryos were incubated 60 min in simplified culture media in the presence of45Ca at 37.5±0.5°C either inside or outside pulsating electromagnetic fields. Radioactivity count in the medium was the most accurate method for determining Ca-uptake by the rudiment. The effect of the fields on the Ca-uptake depended markedly on the chemical composition of the culture medium: bicarbonate was indispensable; glucose or sucrose was important; phosphate was potentiating; ethanol, Mg2+, and NaF were stimulating. The field had no effect in (a) blank medium without tibia, (b) tibiae that had been altered by fixation with aqueous glutaraldehyde, (c) nonliving artificial systems endowed with great or small ion sorption capacity. The unique bicarbonate effect with living systems and the passive behavior of nonliving ion sorbing systems prompt the suggestion that the electromagnetic field probably couples with specific processes, such as a bicarbonate-dependent Ca2+ ATPase and the active ion transport, at the cell membrane level. The molecular mechanisms remain to be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405313
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  • 3
    Electronic Resource
    Electronic Resource
    Benzo(B)Thiophene-2-Carboxylic acid: Calcium uptake and cyclic AMP production in isolated bone cells (1984)
    Springer
    Calcified tissue international 36 (1984), S. 194-199 
    Details
    ISSN: 1432-0827
    Keywords: Benzo(B)Thiophene-2-Carboxylic Acid ; Bone cells ; Calcium ; Cyclic AMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The purpose of the present study was to investigate the mechanism of action on bone of Benzo(B)Thiophene-2-Carboxylic Acid (BL-5583). BL-5583, at a dose range of 0.01–100 µg/ml, inhibited spontaneous as well as A23187 and PTH-induced bone resorption in tissue culture. This compound also decreased calcium uptake in both osteoclastic and osteoblastic enriched bone cell populations obtained by sequential collagenase digestion of 1–2 day newborn rat calvariae. The decrease occurred after a 5 min. incubation with45Ca and BL-5583. The effective dose range was 0.01–100 µg/ml. No effect on leucine incorporation or lactic acid production by bone cells was observed. BL-5583 also induced a transient decrease in calcium uptake in skin cells isolated from fetal rats by collagenase digestion, suggesting a lack of tissue specificity for this compound. No effect on cyclic AMP in isolated bone cells was observed with the same dose range that produced a calcium effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405317
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of vitamin D and parathyroid hormone on cyclic AMP production by bone cells isolated from rat calvariae (1984)
    Springer
    Calcified tissue international 36 (1984), S. 320-326 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Vitamin D deficiency ; 1,25(OH)2D3 ; Parathyroidectomy ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Studies presented here were designed to investigate further the basis for an impaired cAMP response to parathyroid hormone (PTH) in osteoblastlike calvarial bone cells isolated from vitamin D-deficient rat pups. The goal was to perturb Ca, PTH, and vitamin Din vivo in order to see which factors might be responsible for the impairedin vitro bone cell cAMP response. Pups either were parathyroidectomized (PTX) 3–5 days, implanted with osmotic minipumps delivering high doses of PTH, given repeated, high doses of 1,25(OH)2D3, or were D-deficient (-D, i.e., born and suckled by D-deficient mothers). Osteoblastlike bone cells, isolated by sequential enzyme digestion and centrifugation, were exposed to PTH for 5 min in the presence of a phosphodiesterase inhibitor. In bone cells isolated from -D rat pups, both basal and PTH-induced cAMP accumulation were significantly lower than in +D bone cells. Earlier, we had shown that two daily injections of -D pups with 50 ng 1,25(OH)2D3 restores this reduced bone cAMP response of -D pups toward normal. In the present study, neither basal nor PTH-induced bone cell cAMP accumulation was affected by subjecting D-replete pups to PTX, PTH infusion, or repeated high doses of 1,25(OH)2D3 despite the fact that each treatment markedly changed serum Ca or serum immunoreactive PTH. The results indicate that the impaired bone cell cAMP response seen in -D pups is not a direct result of chronic hypocalcemia and that the “heterologous desensitization” seenin vitro with added 1,25(OH)2D3 could not be duplicated byin vivo treatment of +D pups with supraphysiologic doses of 1,25(OH)2D3. Finally the lack of alteration in the bone cell cAMP response to PTHin vitro after chronic PTH infusionin vivo fails to support the notion that the impaired response in -D bone cells can be explained entirely by “homologous desensitization” induced by high circulating levels of PTH in the hypocalcemic, -D rat pup.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405337
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  • 5
    Electronic Resource
    Electronic Resource
    Calcitonin and parathyroid hormone in newborn infants with fracture of the clavicle (1984)
    Springer
    Calcified tissue international 36 (1984), S. 357-360 
    Details
    ISSN: 1432-0827
    Keywords: Calcitonin ; Parathyroid hormone ; Calcium ; Newborn ; Fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Determinations of serum calcium (Ca), phosphorus (P), calcitonin (CT), and parathyroid hormone (PTH) were carried out in 36 full-term newborn infants with fracture of the clavicle (CF) and in 46 normal neonates (N). At the 6th hour of life the CF neonates demonstrated lower serum Ca and higher serum CT in comparison with normal infants. In the hours following, no significant differences between the two groups for the Ca levels were found, whereas serum CT remained significantly higher in the CF newborns at the 24th, 48th, and 72nd hour of life. Significant differences between normal and CF infants in the PTH serum levels were detected only at the 48th hour, when PTH was lower in the CF newborns. The results of this investigation indicate that the fracture of the clavicle is a significant and peculiar factor in stimulating CT secretion. Serum Ca level appeared to be controlled by CT rather than auto-regulating the secretion of the hormone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405346
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  • 6
    Electronic Resource
    Electronic Resource
    Calcium distribution in freeze-dried enamel organ tissue during normal and altered enamel mineralization (1984)
    Springer
    Calcified tissue international 36 (1984), S. 596-603 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Ameloblasts ; X-ray microanalysis ; Transport ; Frozen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Energy dispersive X-ray microanalysis was applied to freeze-dried blocks of enamel organ tissue to determine levels of calcium in various celular regions. The tissue blocks were dissected free from adjacent forming enamel following injection of cobalt or fluoride ions, both of which temporarily inhibit enamel mineralization. In all control and experimental specimens there was an increasing gradient of calcium from the stratum intermedium cells to the distal ends of the ameloblasts. Calcium levels were significantly reduced near the distal ends of the ameloblasts following cobalt or fluoride injection as compared with controls. It is suggested that evidence of an intercellular buildup of calcium near the distal ends of the ameloblast supports a controlling function of these cells. The changes in calcium levels are correlated with alterations in mineralization known to occur in the adjacent enamel of the model systems employed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405373
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  • 7
    Electronic Resource
    Electronic Resource
    Assessment of anin vivo diffusion chamber method as a quantitative assay for osteogenesis (1984)
    Springer
    Calcified tissue international 36 (1984), S. 77-82 
    Details
    ISSN: 1432-0827
    Keywords: Osteogenesis ; Diffusion chambers ; Alkaline phosphatase ; Calcium ; Phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The alkaline phosphatase activity and the calcium and phosphorus content of osteogenic tissue formedin vivo following the implantation of diffusion chambers loaded with rabbit bone marrow cells is reported. (In this study the term osteogenic includes osteoblastic and chondroblastic.) Chambers examined 14–70 days after implantation revealed progressive accumulation of mineral. Alkaline phosphatase activity increased until day 30 and declined thereafter. The osteogenic potential of the marrow cells decreased with increasing weight (age) of the cell donor rabbit when measured either as the percentage of chambers containing osteogenic tissue or as the amount of calcium, phosphorus, or alkaline phosphatase activity within the chambers. The results confirm that measurements of these parameters in tissue formed by cells incubated in diffusion chambersin vivo may be used as a method for assay of osteogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405297
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  • 8
    Electronic Resource
    Electronic Resource
    Mineral loss in cortical and trabecular bone during high-dose prednisone treatment (1984)
    Springer
    Calcified tissue international 36 (1984), S. 269-273 
    Details
    ISSN: 1432-0827
    Keywords: Bone loss (osteopenia) ; Calcium ; Corticosteroids (glucocorticosteroids) ; Fluoride ; Vitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To evaluate the effect of prednisone and triple treatment (sodium fluoride, calcium, and vitamin D) on trabecular and cortical bone serial bone mineral content (BMC) measurements were made at a metaphyseal (BMCD) and diaphyseal (BMCP) site on the forearm on 31 consecutive and previously bone-healthy patients scheduled for at least 24 weeks high-dose prednisone treatment. The patients were randomized into two further treatment groups: group I (n=16) received prednisone plus triple treatment and group II (n=15) received only prednisone. The two groups were similar with regard to age, sex, prednisone dose, and initial BMC. During 24 weeks treatment, BMCD (partially representing trabecular bone) and BMCP (mainly representing cortical bone) fell significantly and similarly, demonstrating that there is no preventive effect on bone mineral loss on the triple regimen. The BMC fall after 12 weeks was significantly more pronounced for metaphyseal (partially trabecular) than for diaphyseal (cortical) bone, whereas the values did not differ significantly after 24 weeks; this indicates a greater sensitivity to the hormone treatment of trabecular bone. In the entire group, the fall in BMC correlated positively with individual prednisone dose, significant at the diaphyseal site (r=0.39,P〈0.05), but not at the metaphyseal site (r=0.31, P=0.08). It is concluded that corticosteroid-induced osteopenia is a diffuse bone disease which affects trabecular as well as cortical bone, suggesting that BMC measured on the forearm reflects changes in bone mineral at other locations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405329
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  • 9
    Electronic Resource
    Electronic Resource
    Hypervitaminosis D in the chick embryo: Comparative study on the activity of various vitamin D3 metabolites (1984)
    Springer
    Calcified tissue international 36 (1984), S. 392-400 
    Details
    ISSN: 1432-0827
    Keywords: Vitamin D ; Chick embryo ; Bone ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Chick embryos were injected in the yolk sac at various ages with various doses of different vitamin D3 metabolites. Serum concentrations of total calcium and inorganic phosphate were determined 24 h after the injection and histological and electron microscopic studies of the tibiae were conducted 3–6 days after. Confirming previous results, the injection of 1,25(OH)2D3 was found to produce significant hypercalcemia and hypophosphatemia. The dose required to produce these effects decreased with age: 100 ng on the 9th day, 50 ng on the 11th, and 10 ng on the 15th. This finding is interpreted as resulting from the fact that the specialized cells in the chorionic epithelium which are considered to be involved in mineral resorption from the shell differentiate between the 11th and 13th days. Although no bone changes were observed in embryos injected before the 11th day, a rim of unmineralized trabeculae (osteoid) was observed at the periphery of the cortex of the tibial diaphysis in the embryos which had been injected after that age. Thus, in embryos injected on the 11th day with 100 ng 1,25(OH)2D3, the trabeculae formed between the 11th and 14th day remained unmineralized until the 15th or 16th day at which time they completed their mineralization. In the embryos injected on the 14th day, the alterations were more severe and could be produced with doses 10 times smaller than those required when the injections were made on the 11th day. At all ages, the doses that produced an osteoid rim also induced hypercalcemia and hypophosphatemia. The electron microscopical study of the osteoid trabeculae showed that osteoblasts and osteocytes had normal cytological characteristics and that the bone matrix did not present changes other than the reduction in mineral deposition. While the above findings do not exclude a direct action of 1,25(OH)2D3 on bone cells as the mechanism of osteoid formation, they do underline the importance of the humoral changes at least as partial determinants of this phenomenon. The activities of various vitamin D metabolites were compared using as parameter the threshold-dose required to produce a rim of unmineralized trabeculae in the tibia of 14–15 days embryos (T-D). The most active metabolite appeared to be 1,25(OH)2D3 (T-D: 10 ng); it was followed by 1,24,25(OH)3D3 (T-D: 100 ng) and 1,25,26(OH)3D3 (T-D: 100 ng). Vitamin D3 itself (T-D: 100 µg), 25(OH)D3 (T-D: 2.5µg) and 24,25(OH)2D3 (T-D: 5 µg) produced similar responses but only when administered in much larger doses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405351
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  • 10
    Electronic Resource
    Electronic Resource
    In vitro precocious accumulation of calcium and matrix vesicles formation in young cartilage cells: Specific effects of corticosteroids (1984)
    Springer
    Calcified tissue international 36 (1984), S. 702-710 
    Details
    ISSN: 1432-0827
    Keywords: Corticosteroids ; Cartilage ; Organ culture ; Calcium ; Matrix vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The present study examined the effects of various corticosteroid and noncorticosteroid hormones upon the ultrastructure of chondroprogenitor cells and chondroblasts in an organ-culture system of late fetal condylar cartilage. Corticosteroids, (triamcinolone acetonide, dexamethasone, corticosterone) at concentrations of 10−6–10−8M stimulated markedly a precocious formation of matrix vesicles by chondroblasts. This stimulation was accompanied by a significant accretion of calcium complexes intra- and extracellularly in both the chondroprogenitor cell population and chondroblastsin vitro, as well as in the newly induced matrix vesicles. Nonglucocorticoid steroids (progesterone, estradiol, testosterone, cortexolone) did not evoke similar effects. Progesterone and testosterone, however, seemed to adversely affect the ultrastructure of the cartilage cells, whereas estradiol appeared to have a favorable effect on the morphology of cultured condylar cartilage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405393
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  • 11
    Electronic Resource
    Electronic Resource
    Pharmacodynamics and pharmacokinetics of xipamide in patients with normal and impaired kidney function (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 513-520 
    Details
    ISSN: 1432-1041
    Keywords: xipamide ; electrolyte excretion ; bioavailability ; elimination ; extrarenal clearance ; chronic renal failure ; furosemide ; hydrochlorothiazide ; amiloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of a single oral dose of 40 mg xipamide on urinary excretion of Na+, K+, Cl−, Ca2+ and Mg2+ in healthy subjects and in patients with varying degrees of renal impairment was compared with various conventional diuretics. Xipamide caused marked excretion of Na+ and Cl−, whereas the diuretic produced only moderate kaliuresis; urinary excretion of Ca2+ was increased in proportion to Na+, like the loop diuretics. Xipamide affected electrolyte excretion even in patients with a creatinine clearance below 30 ml/min, as do the loop diuretics, too. Therefore, the pharmacodynamic characteristics of xipamide are more like those of a loop diuretic than of a thiazide. Xipamide was good bioavailable, its t1/2β was 7 h and urinary recovery of the undegraded drug was 40% of the given dose. In renal insufficiency, t1/2β increased from 7 to only 9 h, yielding a moderate increase in the AUC. Urinary recovery of the drug was reduced in proportion to the reduction in the creatinine clearance of the patient. Therefore, significant extrarenal elimination of the diuretic must be postulated, which suffices to prevent significant drug accumulation in renal failure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542150
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  • 12
    Electronic Resource
    Electronic Resource
    Bioavailability and pharmacokinetics of phenytoin during pregnancy (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 105-110 
    Details
    ISSN: 1432-1041
    Keywords: phenytoin ; epileptic women ; pharmacokinetics ; bioavailability ; pregnancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Five epileptic women needing to commence phenytoin therapy during pregnancy received a single intravenous and a single oral dose of phenytoin several days apart before starting regular intake of the drug. Plasma phenytoin concentration — time data were analysed by three different pharmacokinetic techniques. However assessed, the mean oral bioavailability of the drug proved to be about 90% of the intravenous bioavailability. This finding makes it unlikely that impaired bioavailability accounts for the increase in oral phenytoin dosage necessary in pregnancy to maintain plasma phenytoin concentrations at pre-pregnancy values. Phenytoin clearance in the pregnant subjects was approximately double the published values for phenytoin clearance in nonpregnant persons. This suggests that increased (metabolic) clearance accounts for the increased phenytoin dosage requirement of pregnancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395215
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  • 13
    Electronic Resource
    Electronic Resource
    Implications of intraindividual variability in bioavailability studies of furosemide (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 595-602 
    Details
    ISSN: 1432-1041
    Keywords: furosemide ; bioavailability ; generic tablet formulations ; intrasubject variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Intrasubject variation in bioavailability (rate and extent) and disposition of furosemide 40 mg was investigated using a repeated, randomized, double-blind cross-over study in 8 healthy subjects. Two generic tablet formulations (Lasix and Furix) and intravenous furosemide were compared on 6 separate days. Extensive intrasubject variability after oral administration was observed in AUC, mean absorption time (MAT) and urinary excretion. The variability (error variance) within the dosage forms was as large as that between the two generics. These variations most probably depended on the absorption process, since the repeated i.v. doses showed only marginal intrasubject variability. Absolute bioavailability was 56% for Lasix and 55% for Furix (AUC). The range was 20 to 84% between individuals and the maximal range within one individual was 20 to 61%. Confidence interval and Bayesian analysis showed a high probability of non-equivalence not only between but also within the generics when the separate cross-over experiments were analyzed (8 observations). When extending the analysis to 16 observations, bioequivalence was demonstrated for the two generic tablets. Rate of absorption, quantified as MAT, was 128 min for Lasix and 98 min for Furix (16 observations). Since MAT was significantly longer (p〈0.001) than the mean residence time after the i.v. dose (57 min), absorption was evidently the rate-limiting step in the overall kinetics of oral furosemide. Intraindividual variation in absorption is a confounding factor in bioavailability studies of furosemide using limited numbers of subjects. This is important to consider when designing and evaluating bioavailability studies for drugs showing these variations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00556898
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  • 14
    Electronic Resource
    Electronic Resource
    Food does not effect in bioavailability of theophylline from Theolin Retard® (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 405-407 
    Details
    ISSN: 1432-1041
    Keywords: theophylline ; drug absorption ; bioavailability ; food intake ; sustained-release preparations ; Theolin Retard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absorption of theophylline from a sustained release tablet preparation (Theolin® Retard 300 mg) was studied in 10 subjects both when fasting and immediately after a standardized breakfast. Intravenous aminophylline was used as the reference material. Food did not influence the absorption from Theolin Retard. The bioavailability was complete (93% after 30 h) both with and without food, and no difference was found in the time to peak of the plasma concentration curve (7 h), or the mean residence time (14 h). The absorption characteristics, with predominantly zero order kinetics, did not change with concomitant intake of breakfast.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00548776
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  • 15
    Electronic Resource
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    Effect of food on pharmacokinetics of chlorambucil and its main metabolite, phenylacetic acid mustard (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 111-114 
    Details
    ISSN: 1432-1041
    Keywords: chlorambucil ; chronic lymphocytic leukaemia ; phenylacetic acid mustard ; food intake ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of food intake on the pharmacokinetics of chlorambucil (C) and its cytotoxic metabolite, phenylacetic acid mustard (PAM), has been studied in man after oral doses of chlorambucil. The administration of chlorambucil with food resulted in slower absorption than when fasting. However, the area under the plasma concentration-time curve (AUC) was unaffected. The mean ratio AUCPAM/AUCC was 2.8 (range 1.4–7.1) under fasting and 3.3 (range 1.3–7.4) under nonfasting conditions. The metabolite very probably plays an important role in the cytotoxic effects observed after administration of C, since calculations show that a major fraction of the metabolite is eliminated by alkylation reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553164
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  • 16
    Electronic Resource
    Electronic Resource
    Studies of the bioavailability of nitroglycerin from a transdermal therapeutic system (Nitroderm TTS) (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 7-12 
    Details
    ISSN: 1432-1041
    Keywords: nitroglycerin ; plasma concentration ; transdermal administration ; bioavailability ; pharmacodynamics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 6 healthy volunteers, intravenous infusions of nitroglycerin 4.8 and 10.6 µg/min yielded mean steady-state plasma concentrations of 0.5±0.02 and 0.82±0.04 ng/ml as determined by a gas chromatographic/mass spectrometric method. The plasma concentrations reached in the same subjects 17 h after application of Nitroderm TTS 5 and 10 with in vivo release rates of 3.7 and 5.7 µg/min were 0.28±0.01 and 0.37±0.01 ng/ml, respectively. Thus, 75% of the quantity of nitroglycerin released by the systems passed into the circulation. The inter-individual and intra-individual variations in plasma concentrations were similar for both modes of administration. The nitroglycerin-induced morphological changes in the fingerpulse wave were clearly dose-dependent, but it seems that this pharmacodynamic parameter is determined less by the plasma concentration than by the nitroglycerin content of the vascular wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02395198
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  • 17
    Electronic Resource
    Electronic Resource
    Steady state bioavailability of a new oral formulation of Hydergine® in geriatric patients (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 133-135 
    Details
    ISSN: 1432-1041
    Keywords: co-dergocrine mesylate ; geriatric patients ; hydergine ; bioavailability ; steady state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The relative bioavailability of the newly developed formulation of co-dergocrine mesylate (Hydergine spezial, 1×4 mg) was determined in elderly patients under steady state conditions, with conventional Hydergine forte tablets (2×2 mg) as a reference. Both formulations were given once a day for 8 days in a randomised cross-over design. The areas under the curve showed that the bioavailability of the new tablet was about 30% higher (28±6.3%) than that of Hydergine forte. The peak plasma concentration was reached 3±0.9 h after administration. Because of its greater relative bioavailability higher plasma levels were found 2–24 hours after the Hydergine spezial formulation than after Hydergine forte tablets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00546722
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  • 18
    Electronic Resource
    Electronic Resource
    Bioequivalence studies in humans of indomethacin capsules marketed in India (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 261-264 
    Details
    ISSN: 1432-1041
    Keywords: indomethacin capsules ; bioequivalence ; volunteers ; pharmacokinetics ; statistical significance ; bioavailability ; comparative bioequivalence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Two, separate 6×6 Latin square cross-over bioequivalence studies were performed in adult male volunteers using 10 different indomethacin capsule preparations marketed in India together with the pure drug powder as the standard. The products were evaluated with respect to plasma level at various times up to 8 h following administration of a 50 mg (2 × 25 mg) dose. Plasma samples were analysed by a fluorimetric method. Various pharmacokinetic parameters were calculated according to a two compartment model. Statistical evaluation of the data employed analysis of variance for a cross-over design (ANOVA) and Duncan's multiple range test to ascertain the significance of differences between the products. Of the 10 products studied, two were found to be bioinequivalent.
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  • 19
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    Elucidation of the structure and receptor binding studies of the major primary, metabolite of dihydroergotamine in man (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 463-470 
    Details
    ISSN: 1432-1041
    Keywords: dihydroergotamine ; 8′-hydroxy-dihydroergotamine ; plasma metabolites ; bioavailability ; receptor affinity ; healthy volunteers ; liver microsomal incubates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma concentrations and urinary excretion of dihydroergotamine and its metabolites have been measured after a single oral administration of 3 mg tritium-labelled drug to 6 male volunteers. The plasma level of non-volatile radioactivity declined biphasically with α- and β-phase half-lives of 2.1 h and 32.3 h, respectively. The peak plasma concentration was reached within 3.2h. Urinary excretion of total non-volatile radioactivity was low, amounting to 1.0% of the dose. The parent drug and four metabolites could be quantitated in urine and plasma samples. Metabolite 4 (8′-hydroxy-dihydroergotamine) was isolated from incubates of rat and monkey liver microsomal preparations. In human liver microsomal incubates, metabolite 4 was shown to be the primary metabolite of dihydroergotamine. In receptor binding studies performed with mammalian brain preparations, metabolite 4 had IC50-values at 6 monoaminergic binding sites similar to those of dihydroergotamine. Thus, it appears that the active principle consists at least of dihydroergotamine and its 8′-hydroxy derivative. As the concentration of metabolite 4 exceeded 5–7 times that of dihydroergotamine in urine and plasma, the bioavailability of dihydroergotamine should be reevaluated, taking into account the plasma concentrations of the parent drug and of its acitve metabolite, 8′-hydroxydihydroergotamine.
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    URL: http://dx.doi.org/10.1007/BF00542142
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  • 20
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    Bioavailability of amiodarone (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 533-534 
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    ISSN: 1432-1041
    Keywords: amiodarone ; bioavailability ; clearance estimation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542153
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  • 21
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    Pharmacokinetics of nadolol in healthy subjects (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 125-127 
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    ISSN: 1432-1041
    Keywords: nadolol ; pharmacokinetics ; plasma levels ; urinary excretion ; bioavailability ; circadian rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 7 healthy subjects (3 males and 4 females), the kinetics of nadolol was investigated after oral doses of 60 and 120 mg. The t1/2 was 14.0±1.8 h. The peak plasma level was doubled on doubling the dose (from 69±15 to 132±27 ng/ml, respectively) and the urinary excretion (13.5%) rose similarly. The half-life of elimination was longer at night than in the day, probably because of the slower nocturnal flow of urine.
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    URL: http://dx.doi.org/10.1007/BF00546720
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  • 22
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    The bioavailability and pharmacokinetics of cimetidine and its metabolites in juvenile cystic fibrosis patients: Age related differences as compared to adults (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 183-189 
    Details
    ISSN: 1432-1041
    Keywords: cimetidine ; cystic fibrosis ; bioavailability ; renal clearance ; renal function differences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and metabolism of cimetidine were studied in five cystic fibrosis patients (mean age 12.6 years) after oral and intravenous administration. As compared to healthy adult volunteers, cystic fibrosis children had an elevated cimetidine total body clearance (474 vs 300 ml/min/m2) as well as renal clearance (293 vs 232 ml/min/m2) whether normalized for body weight or surface area differences. Cimetidine elimination was elevated in juvenile cystic fibrosis patients as compared to adult volunteers, however, it did not differ significantly from that previously seen in age matched children. There were no appreciable differences in cimetidine metabolism after either route of administration. Differences between adults and cystic fibrosis children were attributed to developmental and age related differences between the two groups. The recommended pediatric dose of 15 to 20 mg/kg, although four-fold greater than that used in adults, produces serum concentrations similar to those seen in adults, and is adequate for most juvenile cystic fibrosis patients.
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    URL: http://dx.doi.org/10.1007/BF00630284
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  • 23
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    Pharmacokinetics of furosemide in man after intravenous and oral administration. Application of moment analysis (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 197-207 
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    ISSN: 1432-1041
    Keywords: furosemide ; bioavailability ; pharmacokinetics ; oral administration ; i.v. administration ; drug absorption ; moment analysis ; food effect ; dissolution effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Furosemide 40 mg was administered to 8 healthy subjects as an i.v. bolus dose, as 1 tablet in the fasting state, and as 1 tablet and a solution after food intake. The i.v. data gave a total body clearance of 162±10.8 ml/min and a renal clearance of 117±11.3 ml/min; the volume of distribution at steady state was 8.3±0.61. Oral administration gave a bioavailability of the tablet (fasting) of 51%. Food intake slightly reduced the bioavailability, but not to a significant extent. There was no significant difference in availability between the tablet and the solution. Moment analysis gave a mean residence time after the i.v. dose, MRTi.v., of 51±1.5 min. The mean absorption times (MAT) for all oral doses were significantly longer than the MRTi.v., indicating absorption rate-limited kinetics of furosemide. On average, food delayed the absorption by 60 min. The MAT for the tablet in the postprandial state was significantly longer than for the solution, indicating dissolution rate-limited absorption of the tablet.
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    URL: http://dx.doi.org/10.1007/BF00630286
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  • 24
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    Effect of aluminium phosphate on the bioavailability of cimetidine and prednisolone (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 271-273 
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    ISSN: 1432-1041
    Keywords: cimetidine ; prednisolone ; aluminium phosphate ; antacids ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Ten fasting subjects received 200 mg cimetidine orally either with water or 11 g aluminium phosphate mixture in a randomized, single dose, two-way cross-over study. Blood samples were taken for 12 h and urine was collected for 24 h. Cimetidine in plasma and urine was analysed by HPLC. There were no significant differences between the treatments with respect to peak plasma concentration, time to peak plasma concentration, area under the plasma concentration-time curve, and urinary excretion. In 12 healthy subjects the absorption of prednisolone was investigated when given alone and together with 11 g aluminium phosphate. Blood samples were taken over 16 h and prednisolone in plasma was analysed by HPLC. There were no significant differences in the values of area under curve (AUC), Cmax and tmax. The results indicate that aluminium phosphate does not reduce the bioavailability of cimetidine and prednisolone.
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    URL: http://dx.doi.org/10.1007/BF00630299
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  • 25
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    Pharmacokinetics of cimetidine in advanced cirrhosis (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 347-355 
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    ISSN: 1432-1041
    Keywords: cimetidine ; cirrhosis ; pharmacokinetics ; bioavailability ; clearance reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of impaired liver function on the pharmacokinetics of cimetidine was studied in 8 patients with advanced cirrhosis given single doses of 100 mg i.v. and 400 mg p.o. on separate days. Compared to a control group of 10 healthy volunteers, the total renal and nonrenal clearance was significantly reduced in the cirrhotic patients; (total plasma clearance mean ± SD) 356±181 vs 789±262 ml/min (p〈0.01); renal clearance (Clr) 296±100 vs 588±181 ml/min (p〈0.01) and nonrenal clearance (Clnr) 97±111 vs 205±89 ml/min (p〈0.05). Compared to published results for age-matched ulcer patients, both total and nonrenal clearance were lower whereas renal clearance was within the reported normal range. A significant reduction in volume of distribution (Vdβ) was found, from 2.1±0.1 l/kg in controls to 1.0±0.4l/kg, and in the patient group there was a significant correlation between Vdβ and total plasma clearance (r=0.72, p〈0.05). Volume of distribution in steady state (Vdss) did not differ from published results in age-matched controls. No significant change in half-life was found. Bioavailability, estimated by AUC-measurement, showed considerable patient variability (21–143%), with a mean of 70±39%. This was lower than in the controls. In contrast, measurement of urinary excretion showed higher bioavailability in the patients (66±23 vs 51±8%). No correlation was found between any of the kinetic parameters and the clinical and laboratory data. It is suggested that patients with advanced cirrhosis should be closely observed when given cimetidine, and a reduction in dose should be concidered if side effects are to be avoided.
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    URL: http://dx.doi.org/10.1007/BF00548766
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  • 26
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    Bioavailability and pharmacokinetics of phenytoin during pregnancy (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 105-110 
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    ISSN: 1432-1041
    Keywords: phenytoin ; epileptic women ; pharmacokinetics ; bioavailability ; pregnancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Five epileptic women needing to commence phenytoin therapy during pregnancy received a single intravenous and a single oral dose of phenytoin several days apart before starting regular intake of the drug. Plasma phenytoin concentration — time data were analysed by three different pharmacokinetic techniques. However assessed, the mean oral bioavailability of the drug proved to be about 90% of the intravenous bioavailability. This finding makes it unlikely that impaired bioavailability accounts for the increase in oral phenytoin dosage necessary in pregnancy to maintain plasma phenytoin concentrations at pre-pregnancy values. Phenytoin clearance in the pregnant subjects was approximately double the published values for phenytoin clearance in nonpregnant persons. This suggests that increased (metabolic) clearance accounts for the increased phenytoin dosage requirement of pregnancy.
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    URL: http://dx.doi.org/10.1007/BF00553163
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  • 27
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    Effect of food on pharmacokinetics of chlorambucil and its main metabolite, phenylacetic acid mustard (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 111-114 
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    ISSN: 1432-1041
    Keywords: chlorambucil ; chronic lymphocytic leukaemia ; phenylacetic acid mustard ; food intake ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of food intake on the pharmacokinetics of chlorambucil (C) and its cytotoxic metabolite, phenylacetic acid mustard (PAM), has been studied in man after oral doses of chlorambucil. The administration of chlorambucil with food resulted in slower absorption than when fasting. However, the area under the plasma concentration-time curve (AUC) was unaffected. The mean ratio AUCPAM/AUCC was 2.8 (range 1.4–7.1) under fasting and 3.3 (range 1.3–7.4) under nonfasting conditions. The metabolite very probably plays an important role in the cytotoxic effects observed after administration of C, since calculations show that a major fraction of the metabolite is eliminated by alkylation reactions.
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  • 28
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    Studies of the bioavailability of nitroglycerin from a transdermal therapeutic system (Nitroderm TTS) (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 7-12 
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    ISSN: 1432-1041
    Keywords: nitroglycerin ; plasma concentration ; transdermal administration ; bioavailability ; pharmacodynamics ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 6 healthy volunteers, intravenous infusions of nitroglycerin 4.8 and 10.6 µg/min yielded mean steady-state plasma concentrations of 0.5±0.02 and 0.82±0.04 ng/ml as determined by a gas chromatographic/mass spectrometric method. The plasma concentrations reached in the same subjects 17 h after application of Nitroderm TTS 5 and 10 with in vivo release rates of 3.7 and 5.7 µg/min were 0.28±0.01 and 0.37±0.01 ng/ml, respectively. Thus, 75% of the quantity of nitroglycerin released by the systems passed into the circulation. The inter-individual and intra-individual variations in plasma concentrations were similar for both modes of administration. The nitroglycerin-induced morphological changes in the fingerpulse wave were clearly dose-dependent, but it seems that this pharmacodynamic parameter is determined less by the plasma concentration than by the nitroglycerin content of the vascular wall.
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  • 29
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    Pharmacokinetics of oral and rectal flurbiprofen in children (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 367-369 
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    ISSN: 1432-1041
    Keywords: flurbiprofen ; syrup ; suppository ; kinetics ; children ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Eight subjects, aged 6–12 years and weighing 18.8–36.7 kg, received single doses of flurbiprofen 50 or 75 mg (corresponding to 1.4–2.7 mg/kg) as syrup and suppository in a Latin square design. Half-life (2.7–3.2 h), elimination constant (0.22–0.26 h−1), area under the plasma level curve (72.4–77.3 µg·h·ml−1) and time to reach the concentration peak (1–0.75 h) were similar after the syrup and suppository. Flurbiprofen showed equivalent bioavailability after oral and rectal administration and the same pharmacokinetic profile was confirmed in children as observed in adults.
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    Cimetidine bioavailability and variable renal clearance (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 623-624 
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    ISSN: 1432-1041
    Keywords: cimetidine ; bioavailability ; renal clearance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
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    URL: http://dx.doi.org/10.1007/BF00556904
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  • 31
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    Bioavailability of cyclophosphamide from oral formulations (1984)
    Springer
    European journal of clinical pharmacology 26 (1984), S. 269-270 
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    ISSN: 1432-1041
    Keywords: cyclophosphamide ; cytostatic drug ; cancer therapy ; female breast cancer ; bioavailability ; rapid release formulations ; gastric juice resistant formulation ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Cyclophosphamide (CP) is an alkylating cytostatic compound, which is activated to its cytotoxic form in the liver [1]. Since the therapeutic range of CP in the treatment of human tumours, is small like other cytostatics, a constant high bioavailability is essential for its oral administration. Although CP has become one of the most widely used cytostatics [2], there do not appear to have been any bioavailability investigations providing the necessary information. The development of a very sensitive gas chromatographic analytical method has now permited investigation of the pharmacokinetics of oral CP in conventional clinical doses [3, 4, 5, 6].
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  • 32
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    Pharmacokinetics and bioavailability of digitoxin by a specific assay (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 85-89 
    Details
    ISSN: 1432-1041
    Keywords: digitoxin ; radioimmunoassay ; pharmacokinetics ; bioavailability ; digitoxin metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of digitoxin were examined in six normal human subjects using an assay that separates digitoxin from its metabolites. After intravenous administration, the mean systemic clearance was 2.44 ml/min; the volume of distribution was 0.47 l/kg; and the elimination half-life was 6.5 days. After oral administration, the elimination half-life was 5.8 days. The bioavailability was 81.5% using the specific assay. Using a non-specific, direct serum digitoxin radioimmunoassay the bioavailability was 98.0%. Assay of aqueous fractions from extracted serum samples indicated higher levels of water-soluble metabolites following oral compared to intravenous digitoxin administration. These findings suggest that previously reported values for digitoxin bioavailability using non-specific methods may be falsely elevated due to the presence of digitoxin metabolites in serum.
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    Pharmacokinetics and bioavailability of digitoxin by a specific assay (1984)
    Springer
    European journal of clinical pharmacology 27 (1984), S. 85-89 
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    ISSN: 1432-1041
    Keywords: digitoxin ; radioimmunoassay ; pharmacokinetics ; bioavailability ; digitoxin metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of digitoxin were examined in six normal human subjects using an assay that separates digitoxin from its metabolites. After intravenous administration, the mean systemic clearance was 2.44 ml/min; the volume of distribution was 0.47 l/kg; and the elimination half-life was 6.5 days. After oral administration, the elimination half-life was 5.8 days. The bioavailability was 81.5% using the specific assay. Using a non-specific, direct serum digitoxin radioimmunoassay the bioavailability was 98.0%. Assay of aqueous fractions from extracted serum samples indicated higher levels of water-soluble metabolites following oral compared to intravenous digitoxin administration. These findings suggest that previously reported values for digitoxin bioavailability using non-specific methods may be falsely elevated due to the presence of digitoxin metabolites in serum.
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    The role of calcium in stalk development and in phosphate acquisition in Caulobacter crescentus (1984)
    Springer
    Archives of microbiology 138 (1984), S. 140-152 
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    ISSN: 1432-072X
    Keywords: Caulobacter ; Prostheca development ; Stalk function ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Calcium was found to stimulate stalk development in Caulobacter crescentus and to relieve the inhibition of development long known to be caused by phosphate. This suggested that phosphate inhibition could be attributed to its interaction with Ca2+, thereby depriving the cells of a factor that promoted development. Calcium was also found to promote phosphate acquisition by the cells, observed as acceleration of growth at extremes of phosphate concentration, as promotion of carbon-source utilization rather than storage, and as support for phosphate-dependent resistance to arsenate inhibition of growth. Cytological studies of dividing cells revealed that stalked siblings had greater access to exogenous phosphate for use in growth or for storage as polyphosphate, and that access of non-stalked sibling to phosphate was dependent on the length of the stalk of the dividing cell. It was concluded that the physiologic role of the stalk is enhancement of phosphate acquisition. The stimulatory role of calcium in this process was attributed to its support of stalk development and to its stabilization of internal membrane/cell envelope association within the cell-stalk juncture.
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    Elemental analysis of particles in fungal zoospores (1984)
    Springer
    Archives of microbiology 139 (1984), S. 102-104 
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    ISSN: 1432-072X
    Keywords: Fungus ; Zoospore ; Blastocladiella ; Allomyces ; Gamma ; Particle ; Phosphate ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The elemental composition of gamma particles in zoospores ofAllomyces macrogynus andBlastocladiella emersonii was determined by use of energy dispersive X-ray analysis of glutaraldehyde fixed, thin section zoospores. Isolated preparations of gamma particles were also examined. Gamma particles contained no detectable elements. Similar sized, globular, electron dense cytoplasmic inclusions contained phosphorus and calcium. We suggest that previous studies assigning calcium and phosphorus to gamma particles may have been based on confusion of these two types of cytoplasmic inclusions.
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    The role of calcium ions in phytochrome-mediated germination of spores of Onoclea sensibilis L. (1984)
    Springer
    Planta 160 (1984), S. 12-20 
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    ISSN: 1432-2048
    Keywords: Calcium ; Calmodulin ; Germination (spore) ; Onoclea ; Phytochrome and Ca2+ ; Pteridophyta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phytochrome is confirmed to be the photoreceptor pigment in the germination response of Onoclea sensibilis L. by demonstrating red-far-red (R-FR) photoreversibility. External Ca2+ is required for this response with a threshold at a submicromolar concentration. Ethylene glycol-bis(β-amino-ethyl ether)-N,N,N′,N′-tetraacetic acid, La3+ and Co2+ reversibly inhibit germination. Lanthanum only inhibits germination when applied before or during irradiation, indicating that the external Ca2+ requirement is transient, although in the absence of Ca2+ the R-stimulated system remains maximally poised to accept the ion for over 4 h after irradiation. The ability to respond to Ca2+ 4.1 h after R-irradiation is not reversed by FR-irradiation, indicating that Ca2+ transport has been uncoupled from phytochrome. Barium and Sr2+, but not Mg2+ can substitute for Ca2+. Artificially increasing the concentration of intracellular free Ca2+ with the ionophore A 23187 stimulates germination in the dark. The Ca2+-calmodulin antagonists, trifluoperizine and chlorpromazine, reversibly inhibit germination. Calcium is required in phytochrome-mediated fern spore germination; it may be acting as a second messenger.
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    Cytological effects of ionophore-induced stimulation on the exocrine pancreas of the rat (1984)
    Springer
    Cell & tissue research 235 (1984), S. 699-701 
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    ISSN: 1432-0878
    Keywords: Ionophore A-23187 ; Calcium ; Exocrine pancreas ; Secretion ; Zymogen granule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rat-pancreas lobules were incubated with the ionophore A-23187 in the presence of Ca2+. After 90 min, some of the acini were partially or almost completely depleted of their zymogen granules while others had the appearance of resting acini. With few exceptions, the cells of a given acinus were degranulated to a comparable level. Slight dispersion of the zymogen granules was noticed in cells incubated in a Ca2+-free medium containing EGTA with or without A-23187. In the presence of Ca2+ the secretory response obtained with the ionophore was comparable to that observed with 10-5M urecholine. The results obtained provide cytological evidence that the secretory response is only partially determined at the membrane-receptor level and that other mechanisms intervene between cytosol Ca2+ increase and exocytosis.
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  • 38
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    Endoplasmic reticulum whorls as a source of membranes for early cytaster formation in parthenogenetically stimulated sea urchin eggs (1984)
    Springer
    Cell & tissue research 236 (1984), S. 237-244 
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    ISSN: 1432-0878
    Keywords: Aster formation ; Calcium ; Endoplasmic reticulum ; Hypertonic stress ; Parthenogenetic stimulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sea urchin eggs exposed to a continuous hypertonic treatment rapidly form many concentric whorls of endoplasmic reticulum (ER) during the pre-activation period of the parthenogenetic development. These whorls, however, are only a temporary configurational alteration of ER which begin to break up just prior to egg activation. The conversion back to normal vesicles and lamellae occurs not only concurrently with the appearance of early cytastral areas, but also frequently in close association with the formation of these membranous areas. It is revealed here that membrane elements from disrupting whorls may become incorporated into adjacent, developing clear areas, early cytastral areas, and that this ER constitutes an initial major source of membranes for these early astral areas. Having previously suggested that the actual formation of ER whorls occurs in direct response to released intracellular calcium in hypertonic stressed eggs, the new findings, along with other related data and correlations, further suggest that whorl disruption and the formation of associated astral areas can be correlated with a corresponding decrease in the concentration of this released calcium in the cytoplasm.
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  • 39
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    Calcium-induced fusion of fusogenic wild carrot protoplasts (1984)
    Springer
    Protoplasma 120 (1984), S. 209-215 
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    ISSN: 1615-6102
    Keywords: Fusion ; Calcium ; Protoplast ; Membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rather than selecting for a chemical fusogen one can select for a fusogenic plant membrane (i.e., one that will fuse readily). Wild carrot suspension culture cells can be grown under conditions which cause the released protoplasts to have a high potential to fuse. Protoplast fusion is enhanced by calcium and inhibited by EGTA. When 10mM calcium (pH6.0) is added, fusion percentages of 60% are common. The mild fusion treatment appears to have no effect on callus regeneration and differentiation.
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  • 40
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    Liquid chromatography of isomers of aromatic acids on microbore column packed with anion-exchange resin (1984)
    Springer
    Chromatographia 18 (1984), S. 633-636 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aromatic acid isomers ; Low capacity ion-exchange resin ; Microbore packed columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A low-capacity, anion-exchange, porous-polymer resin was used as the packing material in a microbore column. Using a phosphate buffer containing various organic modifiers, retention behavior of substituted benzoic acid isomers with amino, chloro, methyl, nitro and carboxylic groups was investigated. The effect of ethanol, acetonitrile and sodium dodecylsulfate used as organic modifiers on the retention behavior at various eluent pH values was studies and optimum separations of the positional isomers reported.
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    Influence of pressure on sorption equilibrium: HPLC column packing-mixed eluent (1984)
    Springer
    Chromatographia 18 (1984), S. 668-672 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mixed eluents ; Preferential sorption of eluents ; Pressure effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Pronounced base line perturbations were repeatably observed in LC both in alternating recycling and in backflushing experiments when binary eluents and refractometric detectors were used. The perturbations which we call eigenzones appeared immediately after operating the recycling or the backflushing valve, and their size and shape depended on the nature of both the column filling and the mixed mobile phase as well as on the pressure drop across the column. Experimental results presented confirm that the primary causes of the eigenzones were the pressure changes in the columns which influenced the sorption equilibrium of mixed eluent components within the column packing. Some practical consequences of this effect are briefly discussed.
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    Effect of stationary phase properties and solute molecular size on retention of PAHs in reversed-phase liquid chromatography (1984)
    Springer
    Chromatographia 18 (1984), S. 677-679 
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    ISSN: 1612-1112
    Keywords: Polycyclic aromatic hydrocarbons ; Column liquid chromatography ; Polyphenyl bonded phases ; Retention and carbon content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The relationship between the retention of PAHs having various molecular sizes and the carbon contents (%) of bonded stationary phases with various types of ligands were investigated. The examined stationary phases were phenyl, diphenyl, triphenyl and benzyl-bonded silicas. The data indicated that sometimes it is not true that the retention of any solute relates linearly to the carbon content of the stationary phase. As the result, it is suggested that the pore size distribution of the silica support, the bulkiness of the ligand bonded to the silica and the molecular size of solute should also be considered before any precise statement can be made.
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    Implications of on-line FTIR detection in the separation of coal-derived products via HPLC with polar modifiers (1984)
    Springer
    Chromatographia 18 (1984), S. 175-182 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fourier transform IR ; Polar compounds ; Coal products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fourier-transform infrared spectrometry (FTIR) was utilized as a detection system for high-performance liquid chromatography of polar compounds on a normal bonded-phase system. In addition to FTIR, UV (254 nm) and refractive index detection were employed in the separation of model compounds containing oxygen and nitrogen atoms in their molecules (phenols, alcohols, neutral and weakly basic nitrogen compounds). A polar amino-cyano (PAC) bonded-phase column was employed with a binary mobile phase (98:2 CDCl3:CH3CN). The separations and the information gained from each detector is discussed, including interactions between sample material and mobile phase. A polar fraction of a coal-derived product is also chromatographed under identical conditions. The results based on FTIR detection and chromatographic retention behavior suggest the exclusive presence of hindered and unhindered phenols.
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    Microcomputer-assisted retention prediction system in reversed-phase HPLC (1984)
    Springer
    Chromatographia 18 (1984), S. 211-215 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alkylbenzenes ; PAHs ; Retention prediction ; Microcomputer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The microcomputer-assisted retention prediction system in C18 reversed-phase HPLC is described. The system is based on the use of the hydrophobic parameter and the correlation factor of alkylbenzenes and polycyclic aromatic hydrocarbons (PAHs) which are highly correlated to their retention in reversed-phase HPLC. The system is evaluated by comparing the retention data between measured and predicted values. One of the typical examples applied for PAH analysis in the extracts of diesel particulate matter shows the high potential of the system investigated.
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    The synthesis and characterization of aliphatic sulfonic acid cation exchangers for HPLC (1984)
    Springer
    Chromatographia 18 (1984), S. 216-220 
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    ISSN: 1612-1112
    Keywords: Cation exchangers ; Column liquid chromatography ; Exchange capacity, determination ; Organic peroxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two oxidation procedures for the synthesis of silicabased aliphatic sulfonic acid cation-exchangers for HPLC are described. Several reaction conditions for oxidizing a terminal-bonded thiol with organic peroxides are provided along with their yields, capacities, reproducibility, and chromatographic behavior. Also, three methods for determining exchange capacity are discussed, and their relationship to the capacity factors of charged solutes is compared. The maximum capacity determined by the titration of the bonded silica was 0.34 meq/gram. The general problems of synthesizing cation-exchangers, measuring their efficiencies and exchange capacities, and evaluating their overall performances are outlined.
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    Equilibria effects in the dynamic ion-exchange separation of metal ions (1984)
    Springer
    Chromatographia 18 (1984), S. 369-373 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exchange ; dynamic ; Metal ions ; Equilibria effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Equilibria occurring during the dynamic ion exchange separation of metal ions were examined, and their effect on the chromatography of the metal ions was evaluated. Bonded reversed-phase silica, pure organic reversed phase, and silica columns were used to differentiate between the role of silica and the reverse phase. The results show that system peaks had the most important influence on the applicability of dynamic exchangers to quantitative metal ion determinations. The response of system peaks to sample composition (pH, ionic strength, matrix effects) was complicated and could not be predicted easily. Equilibria effects that can cause analytical errors were identified and recommendations for elimination of such errors are given.
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    Detectability of phenols and amines by normal phase microbore HPLC-FTIR employing hihgly IR transparent solvents (1984)
    Springer
    Chromatographia 18 (1984), S. 396-400 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amines ; Phenols ; Fourier transform I.R.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several chromatographic parameters have been examined as to their effect on detectability for microbore high-performance liquid chromatography coupled with Fourier-transform infrared spectrometry. Detection limits for several compound classes are presented as amount injected. Improvements in detectability for this technique are discussed.
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    Determination of thiamine and thiamine phosphates as thiochrome derivatives by reversed-phase chromatography on polystyrene packing materials (1984)
    Springer
    Chromatographia 18 (1984), S. 424-426 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polystyrene packings ; Pre-column derivatization ; Thiamine compounds ; UV and fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatography of thiochrome and related phosphate esters was studied on two different polystyrene packing materials. The adsorbents were compared with respect to capacity factors, plate heights and resolution factors measured with different mixtures of phosphate buffer (pH 8.5) and methanol. In contrast with derivatized silica, these phases were found to be stable using an alkaline mobile phase and sample. Fast separations were possible with good peak symmetry at all organic modifier concentrations.
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    HPLC-analyses of plant biomass hydrolysis and fermentation solutions (1984)
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    Chromatographia 18 (1984), S. 445-448 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino-bonded stationary phase ; Ion-exchange ; Fermentation solution ; Biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this work the analytical separation of biomass hydrolysis and fermentation products is described. Aminobonded phase and ion exchange materials (HPX 87H, HPX 42A, μ Spherogel Carbohydrate) were used as HPLC stationary phases for the determination of monomeric and oligomeric carbohydrates, carbohydrate degradation and fermentation products. The HPX 42A and the amino-bonded phase columns are especially suitable for the analysis of the gluco oligomers. The HPX 87H column separates the monomeric sugars and their degradation and fermentation products (e.g. furfurals and ethanol) very well. Using the μ Spherogel Carbohydrate column the lower gluco-oligomers as well as the monomeric sugars and their degradation and fermentation products, can be determined within 35 minutes.
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    High-performance liquid chromatographic resolution of enantiomers on chiral amine-bonded silica gel (1984)
    Springer
    Chromatographia 18 (1984), S. 459-461 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral bonded phase ; Racemate resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chiral stationary phase with an immobilized, optically active diamine was prepared for the separation of enantiomers. The synthesis of the phase was carried out by bonding (−)trans-1,2-cyclohexanediamine to microparticulate silica gel through the coupling agent 3-glycidoxypropylsilane. The resolution of the racemic compounds catechin, 2,2′-dihydroxy-1,1′binaphthyl and trans-1,2-cyclohexandiol, is reported.
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    Molecular-shape recognition of polycyclic aromatic hydrocarbons in reversed phase liquid chromatography (1984)
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    Chromatographia 18 (1984), S. 495-498 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; PAHs ; Molecular shape recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The molecular-shape recognition of polycyclic aromatic hydrocarbons has been studied on various stationary phases in reversed-phase high-performance liquid chromatography. The examined stationary phases were phenyl-, diphenyl-, triphenyl- and benzyl-bonded silicas. The results of regression analysis inidcated that triphenylsilica is the best packing material to recognize the difference in the molecular-shape of structural isomers. This fact was confirmed by the separation of 4-ring isomers.
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    Effect of the chain length of chemically bonded phases on the retention of substituted benzene derivatives in reversed-phase liquid chromatography (1984)
    Springer
    Chromatographia 18 (1984), S. 499-502 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention data ; Substituted benzene derivatives ; Correlations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The capacity factors of substituted benzene derivatives on bonded phases of various chain lengths in the reversed-phase mode have been measured and correlation of retention data between four stationary phases has been investigated by linear regression analysis. As a result, a difference in the retention mechanism between phases of shorter chain length and octadecylsilica was observed. In addition, it is also apparent that the multicombination treatment between retention data and descriptors such as π, HA, HD and σ promises the possibility of predicting the retention of substituted benzene derivatives on various reversed-phase stationary phases.
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    High-speed analysis of dansyl derivatives of polyamines (1984)
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    Chromatographia 18 (1984), S. 525-527 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyamines ; Dansyl derivatives ; Peak compression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Analytical conditions for the high-speed, reversed-phase, liquid chromatographic of a diamine (putrescine) and polyamines (spermine and spermidine) were determined. Various elution modes were employed using the same mobile phase constituents: 20mM sodium heptane sulfonate and 20mM acetic acid as solvent A and, pure acetonitrile as solvent B. Samples were derivatized with dansyl chloride before injection. Under isocratic conditions, the separation of the three polyamines was achieved in 7 min. The use of a linear elution gradient led to the same analytical time but with a better resolution of the putrescine peak from non-polyamine frontal peaks. For these measurements, the sample size was 5μl. This volume was increased to 20μl and the use of a steep gradient combined with the peak-compression technique allowed a fast analysis in 2–3 minutes, which may be compared with a 30 min run time necessary when a conventional column is used.
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    Response to chilling stress in plant cells II. Redistribution of intracellular calcium (1984)
    Springer
    Protoplasma 121 (1984), S. 17-24 
    Details
    ISSN: 1615-6102
    Keywords: Chilling-sensitivity ; Calcium ; Chlortetracyline ; A 23187 ; Lycopersicon ; Digitalis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have investigated the possibility that the rapid low temperature effects upon cyclosis and subcelluar structure might be due to a breakdown in compartmentation of intracellular calcium, leading to an increase in cytoplasmic Ca2+. Changes in fluorescence of chlortetracycline (CTC), a probe for membrane-bound Ca2+ were monitored in the corners of individual trichome cells (effective spot size ca. 800 square microns) with the aid of a Zeiss epifluorescence microscope linked to a Zeiss Zonax analyzing system. A consistent decrease in signal was observed as cells of chilling-sensitiveLycopersicon esculentum Mill. (cv.Ace) were cooled below their threshold temperature for chilling sensitivity. On rewarming, as the temperature rose above the chilling threshold, there was an increase in fluorescent signal. In contrast, trichomes ofDigitalis purpurea (chilling-resistant) showed no such changes. The uncoupling agent, CCCP, and the Ca2+-chelator, EGTA, induced marked decreases in the fluorescent signal in cells from both species. A more direct approach to testing the hypothesis was to examine the effect of modulating cytoplasmic Ca2+ with the aid of the Ca2+ -ionophore A 23187 and a Ca2+ concentration series in EGTA buffer. Above 10−8 M external free Ca2+, streaming began to be inhibited, full inhibition occurring at 5 x 10−6M Ca2+. The strand structure started to disappear when the Ca2+ rose above 10−7M. Disappearance of strands was accompanied by an increase in the number of cells with vesiculated cytoplasm, an effect analogous to that of chilling temperatures on these cells. The phenothiazines, trifluoperazine and chlorpromazine (10−5M) had similar effects. However but such effects were not seen with R 24571 or N(6-aminohexyl)5-chloro-1-napthalenesulfonamide (W 7) until concentrations were reached that orders of magnitude above their IC50 for calmodulin.
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    Tentacle contraction inDiscophrya collini: The effects of ionophore A23187 and ruthenium red on Ca2+-induced contraction and uptake of extracellular calcium (1984)
    Springer
    Protoplasma 122 (1984), S. 125-131 
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    ISSN: 1615-6102
    Keywords: Calcium ; Contraction ; Discophrya ; Ionophore A23187 ; Ruthenium red ; Tentacles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The tentacles of the suctorian protozoonDiscophrya collini are stimulated to contract by externally applied Ca2+. The role of extracellular Ca2+ in tentacle contraction was studied by monitoring45Ca2+ uptake, using ionophore A23187 to facilitate membrane transport of calcium and ruthenium red (RR) as an inhibitor of transport. The degree of tentacle retraction was dependent upon external Ca2+ concentration and studies with45Ca2+ using scintillation counting indicated a linear relationship between external Ca2+ concentration and Ca2+ uptake. Uptake of Ca2+ was enhanced in the presence of the ionophore while RR caused little inhibition.45Ca2+ uptake was only partially inhibited by RR when cells were subjected to a Ca2+, ionophore and RR mixture. Grain counts from light microscope autoradiographs after treatment of cells with45Ca2+/ionophore,45Ca2+/RR or45Ca2+ alone showed heavy, light and intermediate labelling respectively. In all instances the grains were evenly distributed within the cell. These observations are interpreted as supporting the suggestion that the ionophore enhances both the uptake of extracellular Ca2+ and release of Ca2+from an internal source, while the RR could only partially prevent movement of Ca2+ through the plasma mebrane. A model is presented suggesting that tentacle retraction is mediated by cytosolic Ca2+ levels which are determined by the fluxing of Ca2+ across the plasma membrane and the membrane of elongate dense bodies which act as internal Ca2+ reservoirs.
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    Absence of a significant pharmacokinetic interaction between hydrochlorothiazide and triamterene when coadministered (1984)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 575-586 
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    ISSN: 1573-8744
    Keywords: hydrochlorothiazide ; triamterene ; hydroxytriamterene sulfate ; pharmacokinetics ; bioavailability ; renal clearance ; interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate were monitored in the plasma and urine of 24 healthy young men taking single doses of a liquid preparation containing both hydrochlorothiazide and triameterene, liquid preparations containing either of these drugs alone, and a combination tablet recently formulated with a dose ratio of hydrochlorothiazide: triamterene (1∶1,5) found to give optimal potassium-sparing effect. In contradiction to a recent publication, no interaction between the drugs affecting the bioavailability or renal clearance of either could be demonstrated. The previous report of drug-drug interaction probably arose from formulationrelated problems with bioavailability from the two capsule and two tablet products which had been studied. A well-formulated hydrochlorothiazide-triamterene combination tablet promotes plasma concentrations and urinary excretion of hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate which are virtually identical to those seen after either a combination liquid dosage form or simple liquid forms containing only one of the two drugs.
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    Disopyramide pharmacokinetics and bioavailability following the simultaneous administration of disopyramide and14C-disopyramide (1984)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 289-313 
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    ISSN: 1573-8744
    Keywords: protein binding ; pharmacokinetics ; bioavailability ; disopyramide ; heart failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pharmacokinetics and bioavailability of total (bound plus unbound) and unbound disopyramide were compared following the simultaneous administration of an oral dose of disopyramide and an intravenous dose of14C-disopyramide in five normal volunteers and in 11 patients with congestive heart failure. The binding of disopyramide varied between 60 and 92% in patients and between 81 and 88% in normal subjects at postequilibrium drug concentrations of 10−7M. The binding of disopyramide to serum protein was concentration-dependent in all study subjects at serum concentrations achieved following drug administration. The association constant for the first binding site in serum from normal subjects and patients averaged 8.7X105 M−1 and 4.4X10 5 M−1, respectively (p 〈 0.05). The unbound clearance of disopyramide averaged 277ml/min and 209 ml/min in normal subjects and in patients (p 〈 0.05). When normalized for body weight, the unbound clearance between patients and normal subjects was not significantly different. The elimination half-life of unbound concentrations in normal subjects and in patients averaged 4.9 and 6.1 h, respectively (p 〈 0.05). The clearance and elimination half-life of total disopyramide was the same in both groups. Although the bioavailability of disopyramide averaged 0.85 in both groups, it was more variable in patients owing to the variability in the fraction of the dose absorbed. The unbound renal clearance and volume of distribution at steady state of disopyramide was related to cardiac index. The ratio of elimination half-lives of total and unbound disopyramide was related to the extent of serum protein binding.
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    Lack of influence of an intensive antacid regimen on theophylline bioavailability (1984)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 315-331 
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    ISSN: 1573-8744
    Keywords: theophylline ; antacids ; interaction ; bioavailability ; steady state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We examined the influence of a large-volume, therapeutic antacid regimen, administered for three full days, on the steady-state bioavailability of a conventional-release and sustained-release theophylline product, Aminophyllin and Theodur, respectively. Nine stable asthmatics voluntarily completed a four-phase investigation requiring a total stay of 12 days in the Clinical Research Unit. The treatments consisted of administration of the formulations mentioned with and without antacids to each patient in a randomized sequence. Four patients participated in an additional phase where antacids were administered q2h around the clock for three days. After coadministration of theophylline plus antacids for two days, theophylline therapy was discontinued while numerous blood samples were obtained over 22 hr and analyzed for theophylline content via radioimmunoassay. Antacids had no predictable, consistent influence on theophylline absorption rate as determined by the absorption rate constant, the time to maximal theophylline concentration, or the lag time for theophylline absorption. Antacids had no detectable influence on theophylline elimination half-life and had no consistent, statistically significant effect on the extent of theophylline bioavailability, according to measurements of maximal concentration, AUCmeasured over the appropriate steady-state dosing interval, or elimination-rate adjusted AUC.The substantial intraindividual changes for all parameters of theophylline bioavailability that occurred for control and treatment phases likely represent spontaneous, random between-day variability in theophylline disposition independent of antacid administration, as evidenced by the comparability of the percent coefficient of variation for parameters of biovailability across all phases. Our data demonstrate that therapeutic antacid administration has no effect on steady-state theophylline bioavailability and does not alter the intrinsic variability in theophylline absorption. Based on the results of our data, it is unlikely that a clinically significant (〉20%) decrease in theophylline absorption would occur in any patient treated intensively with antacids concurrently.
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    A new statistical procedure for testing equivalence in two-group comparative bioavailability trials (1984)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 83-91 
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    ISSN: 1573-8744
    Keywords: bioavailability ; bioequivalence ; hypothesis tests ; sample size determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The clinical problem of testing for equivalence in comparative bioavailability trials is restated in terms of the proper statistical hypotheses. A simple t-test procedure for these hypotheses has been devloped that is more powerful than the methods based on usual (shortest) and symmetric confidence intervals. In this note, this new procedure is explained and an example is given, including the method for sample size determination.
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    Theoretical considerations in the calculation of bioavailability of drugs exhibiting Michaelis-Menten elimination kinetics (1984)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 437-450 
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    ISSN: 1573-8744
    Keywords: first-pass ; bioavailability ; Michaelis-Menten ; volume of distribution ; absorption rate constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two approaches used for bioavailability determination of drugs with Michaelis-Menten elimination kinetics were examined by computer simulation. The first method involved treating the drug as though its clearance remained constant during elimination, and the conventional method of taking the ratio of areas under the curve resulting from the oral and intravenous doses was used to calculate bioavailability. The second approach involved using the Michaelis parameters, Vmax and Km,to determine concentration dependent clearance values, but based these calculations on peripheral drug concentrations rather than on concentrations entering or in the liver. We have developed a simulation method that was used to test the accuracy of the above two methods. In the simulations described, Vmax, Km,and hepatic blood flow were chosen to represent a drug with an extraction ratio of 0.9 under linear conditions, but with Michaelis-Menten kinetics occurring at the doses given. Absorption was assumed to be first-order, and metabolism was assumed to occur only in the liver. These simulations showed that the most accurate determination of bioavailability requires knowledge of the direct contribution of oral absorption to the concentration of drug entering the liver. Unexpectedly, the results also showed that if a drug has a large volume of distribution or a large absorption rate constant, or both, use of the much simpler conventional method of bioavailability determination may be appropriate even in cases where the degree of saturation is substantial.
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    Soil organic matter and structural stability: mechanisms and implications for management (1984)
    Springer
    Plant and soil 76 (1984), S. 319-337 
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    ISSN: 1573-5036
    Keywords: Aggregates ; Aluminium ; Bacterial mucilage ; Binding agents ; Calcium ; Cation bridges ; Complexing agents ; Dispersion ; Electron microscopy ; Electrophoretic mobility ; Fungal hyphae ; Glues Iron ; Management Periodate ; Polysaccharides ; Rhizosphere ; Roots ; Slaking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The stability of pores and particles is essential for optimum growth of plants. Two categories of aggregates macro- (〉 250 μm) and micro- (〈250 μm) depend on organic matter for stability against disruptive forces caused by rapid wetting. Dispersion of clay particles from microaggregates is promoted by adsorption of complexing organic acids which increase the negative charge on clays. The acids are produced by plants, bacteria and fungi. However, the dispersibility of clay in microaggregates is offset by the binding action of polysaccharides, mainly mucilages produced by bacteria, but also by plant roots and fungal hyphae. The stability of microaggregates is also enhanced by multivalent cations which act as bridges between organic colloids and clays. Macroaggregates are enmeshed by plant roots, both living and decomposing, and are thus sensitive to management, and increase in number when grasses are grown and the soil is not disturbed. Lack of root growth,i.e. fallow, has the opposite effect. Various implications for management of soil structure are discussed.
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    URL: http://dx.doi.org/10.1007/BF02205590
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    Soil acidity factors and nodulation ofTrifolium repens (1984)
    Springer
    Plant and soil 78 (1984), S. 367-379 
    Details
    ISSN: 1573-5036
    Keywords: Acidity ; Aluminium ; Calcium ; Manganese ; Nodulation ; pH Rhizobium ; Rhizosphere ; Root elongation ; Root hairs ; Trifolium repens ; White clover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Effects of factors associated with soil acidity (low pH, low calcium, high aluminium and high manganese) on theTrifolium repens-Rhizobium trifolii symbiosis were investigted under laboratory conditions using an axenic solution-culture technique. 200 μM manganese increased root elongation in the range pH 4.3–5.5, but had no effect on root hair formation, the number of Rhizobium in the rhizosphere, or nodule formation. Root elongation and root hair formation were unaffected at pH 4.3 when 500 or 1000μM calcium was supplied, whereas multiplication of Rhizobium in the rhizosphere and nodulation were inhibited at pH 4.3 and 4.7.50–1000μM calcium had no effect either on the multiplication of Rhizobium in the range pH 4.3–5.5, or on nodule formation in the absence of aluminium. 50 μM aluminium inhibited, root elongation and root hair formation at pH 4.3 and 4.7; the effect on root elongation was reduced by increasing the calcium concentration from 50 to 1000μM. 50μM aluminium also inhibited Rhizobium multiplication in the rhizosphere and reduced nodule formation at pH 5.5 (at which aluminium precipitated out of solution), but root elongation and root hair formation were unaffected. These, effects of aluminium at pH 5.5 may explain the poor response to inoculation by white clover in acid mineral soils after liming.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450370
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    Stabilité biologique et comportement physique d'un complexe argilo-humique placé dans différentes conditions de saturation en calcium ou en potassium (1984)
    Springer
    Plant and soil 77 (1984), S. 271-284 
    Details
    ISSN: 1573-5036
    Keywords: Calcium ; Cation de liaison ; Complexes organo-minéraux ; Minéralisation ; Stabilisation de la matière organique ; Structure ; Calcium ; Cation bridge ; Fixation of organic matter ; Mineralisation ; Organomineral compounds ; Structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Summary By gradually removing the exchangeable calcium held by the organo-mineral complex of an organic soil from the Jura mountains, the authors showed: a direct action of the microflora on the mineralisation of organic matter (Fig. 7) and on the generation of mineral nitrogen (Fig. 3); an indirect action by the mineralisation of organic matter on the destabilisation of the clay-humus complex. They therefore concluded that the reduction of calcium resulted in the destabilisation of the organo-mineral complex by H+, produced by the biodegradation of the most labile portion of the organic matter. The clay humus complex gradually dissociated. This process lead to the destruction of aggregates and organo-mineral complexes. The organic matter released became biodegradable due to the shortage of calcium.
    Notes: Résumé Les auteurs sont partis d'un complexe organo-minéral calcique provenant d'un sol humifère du Jura et ont provoqué une diminution progressive au cours du temps du taux de calcium échangeable. L'étude de l'évolution de divers paramètres, menée parallèlement, a permis d'analyser les effets directs et indirects de la baisse du calcium sur le complexe organo-minéral. Les résultats obtenus concernent: 1. les effets directs de l'action minéralisatrice de la microflore sur la dégradation de la matière organique (Fig. 7) et la production d'azote minéral (Fig. 3). 2. les effets indirects de cette minéralisation sur la déstabilisation du complexe argilo-humique (Fig. 8). Ils permettent d'affirmer qu'un complexe organo-minéral calcique évolue très rapidement quand l'apport d'ions calcium vient à diminuer ou à être supprimé. Les ions Ca2+ sont très vite déplacés et remplacés par des ions H+ produits par la biodégradation des fractions les plus labiles de la matière organique. Le complexe argile-calcium-humus est progressivement dissocié. Le processus conduit à une destruction des agrégats avec libération des argiles et de la matière organique qui devient à son tour biodégradable. l'effet stabilisateur du calcium ayant disparu.
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    URL: http://dx.doi.org/10.1007/BF02182930
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    Relationships of bio-climatic zones and lithology with various characteristics of forest soils in Greece (1984)
    Springer
    Plant and soil 79 (1984), S. 101-121 
    Details
    ISSN: 1573-5036
    Keywords: Base saturation ; Bio-climatic zones ; Calcium ; Clay accumulation ; Copper ; C:N ratio ; EDTA ; Forest soils ; Greece ; Iron ; Magnesium ; Manganese ; Nitrogen ; Phosphate ; Potassium ; Soil classification ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soils derived from a number of different parent materials (lithologies) and developed along a climatic gradient, manifested by the altitudinal succession of natural vegetation zones (Mediterranean, sub-Mediterranean, Mountainous and Pseudoalpine), were sampled throughout mainland Greece. In soils derived from siliceous parent materials low in clay, acidity increase and percent base saturation decreases from the Mediterranean to the Pseudoalpine vegetation zones. Clay illuviation is found mainly in soils developed in the Mediterranean and the sub-Mediterranean zones. No such changes are apparent in clayey soils rich in bases. Organic matter content of the mineral portion of the soil profile increases by a factor of 2 with a decrease in mean annual air temperature of about 10°C. The pattern of change in clay and soil organic matter content with climate is in relatively good agreement with soil development trends in the area, when soil profiles are named according to the FAO-Unesco soil map of the world. Concentrations of Ca and Mg decrease and those of total N, total and extractable P, K, Fe, Mn and Zn increase from the Mediterranean to the Mountainous zone. Within the same zone, however, concentrations of N, Ca, K, Fe, Mn and Zn decrease, but those of Mg, total and extractable P increase with soil depth. The concentrations of most macro- and micronutrients in the humic horizon are several times higher than those in the mineral portion of the soil profile due to biological enrichment.
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    URL: http://dx.doi.org/10.1007/BF02182148
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    Vesicular-arbuscular mycorrhizal infection in lettuce (Lactuca sativa) in relation to calcium supply (1984)
    Springer
    Plant and soil 82 (1984), S. 61-67 
    Details
    ISSN: 1573-5036
    Keywords: Calcium ; Glomus caledonium ; Glomus mosseae ; Lactuca sativa ; Vesicular-arbuscular mycorrhiza
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Infection of lettuce roots (Lactuca sativa L.) by the vesicular-arbuscular mycorrhizal fungiGlomus caledonium andGlomus mosseae was dependent on the amount of calcium (supplied as CaCl2·2H2O or CaSO4·2H2O) in the nutrient solution; those plants growing at low calcium concentrations being poorly infected.
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    URL: http://dx.doi.org/10.1007/BF02220770
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    Aluminium toxicity expression nutrient uptake, growth and root morphology ofTrifolium repens L. cv. ‘Grasslands Huia’ (1984)
    Springer
    Plant and soil 82 (1984), S. 101-116 
    Details
    ISSN: 1573-5036
    Keywords: Aluminium toxicity ; Calcium ; Phosphate ; Trifolium ; Uptake ; Nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Hydroponic experiments were undertaken to examine the effect of increasing aluminium levels on the mineral nutrition and root morphology ofT. repens growing in nutrient solution. Toxicity symptoms appear between 27.8 and 47.5 μM Al3+ activity (148 to 297 μM total aluminium). The threshold level corresponding to a 10% reduction in leaf fresh weight is estimated to be approximately 20 μM Al3+ activity. The concentration of aluminium in the leaves of white clover increases exponentially with aluminium activity in the nutrient solution. The uptake of divalent cations was inhibited but aluminium enhanced potassium and nitrogen concentrations in both leaves and roots. At high pH (pH 6.0) the speciation of aluminium is controlled by the formation of solid aluminium phosphate and aluminium hydroxide except at the lowest aluminium level (37 μM) where 99.9 per cent is present as the DTPA complex. As the concentration of total aluminium increases, the percentage of Al-DTPA and soluble aluminium hydroxide decreases whilst solid Al(OH)3 increases rapidly to reach a maximum of 91.6 percent (of the total aluminium) in the 1180 μM aluminium treatment. At pH 4.5 the dominant forms of aluminium are free aluminium ion Al-DTPA, AlSO 4 + and AlOH2+. The roots of aluminium stressed plants showed symptoms typical of aluminium toxicity.
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    URL: http://dx.doi.org/10.1007/BF02220774
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    Seasonal changes in foliar macronutrients (N, P, K, Ca and Mg) inEucalyptus saligna Sm. andE. wandoo Blakely growing in rehabilitated bauxite mine soils of the Darling Range, Western Australia (1984)
    Springer
    Plant and soil 81 (1984), S. 377-388 
    Details
    ISSN: 1573-5036
    Keywords: Calcium ; Eucalyptus saligna ; Eucalyptus wandoo ; Foliar nutrients ; Magnesium ; Nitrogen ; Phosphorus ; Potassium ; Rehabilitation ; Seasonal trends
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Seasonal changes in the foliar concentration of macronutrients (N, P, K, Ca and Mg) in sapling trees ofEucalyptus saligna Sm. andE. wandoo Blakely growing in rehabilitated bauxite mined areas in the Darling Range of Western Australia are described. Foliar N concentration decreased with age of the fully expanded leaf tissue. Leaf N concentrations were also high when rates of litter decomposition were expected to be high during the period of early spring. The greatest foliar N difference between trees growing in good soil conditions and those from poorer soil conditions also occurred during this period. Levels of P in leaves were highest in young developing leaves but once the leaves reached full size, no seasonal trend in P concentration was observed. Foliar K was lower during the winter and probably related to the period of maximum leaching by precipitation. High foliar K during summer, however, could be related to the role of K in lowering cellular water potential. Leaf Ca was highest during early sping. Low mobility of cellular Ca during the cool portion of the year was indicated. Foliar Mg showed a weak pattern of decreasing concentration with leaf age. The best season for sampling for these broadleafed evergreen species to provide information on plant nutrient status appears to be in spring.
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    URL: http://dx.doi.org/10.1007/BF02323052
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    Adsorption and exchange of Ca, Mg and K-ions on the root cell walls of clover and rye-grass (1984)
    Springer
    Plant and soil 80 (1984), S. 181-190 
    Details
    ISSN: 1573-5036
    Keywords: Adsorption ; Calcium ; CEC ; Cell wall ; Clover ; Exchange ; Magnesium ; Model ; Potassium ; pH ; Root ; Rye-grass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The ion exchange properties of clover and rye-grass root cell walls were studied quantitatively. Three sets of experiments were performed: adsorption of Ca, Mg and K ions versus pH, adsorption versus cation concentration and exchange isotherms Ca−Mg and Mg−K. A model has been developed. It allows the satisfactory prediction of results (except for pH curves) with the adjustment of a minimum of parameters. The total charge (RT), on its own, accounts for the difference between the ion exchange properties of the clover and rye grass cell walls. The selectivities observed on root material are very different from those observed on soil exchange complexes. The decreasing affinities of cell walls for cations follow the sequence: Ca〉Mg≫K for cell walls. These differences of selectivity are much larger than those usually observed for soil exchange complexes.
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    URL: http://dx.doi.org/10.1007/BF02161174
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    Foliar and twig macronutrients (N, P, K, Ca and Mg) in selected species ofEucalyptus used in rehabilitation: sources of variation (1984)
    Springer
    Plant and soil 81 (1984), S. 363-376 
    Details
    ISSN: 1573-5036
    Keywords: Branch nutrients ; Calcium ; Eucalyptus saligna ; Eucalyptus wandoo ; Foliar nutrients ; Magnesium ; Nitrogen ; Phosphorus ; Potassium ; Rehabilitation ; Soil nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The macronutrient variation within four 6 year oldEucalyptus saligna and four 5 year oldE. wandoo growing on rehabilitated bauxite pits was determined. Significant differences in mean nutrient concentrations were generally recorded between good soil condition sites and poor soil sites, between tree individuals, branch height, and plant organ type; but mean nutrient values were not different among canopy aspects. Fully expanded leaves of the current year provided the most uniform nutrient levels among the plant organs and showed major differences between sites with good soil nutrient conditions and those with poor conditions. Differences in foliar and branch levels of N, P, K, Ca and Mg, the variation between sites, canopy heights and plant organ types, and the use of foliar nutrient levels to indicate deficiencies are discussed.
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    URL: http://dx.doi.org/10.1007/BF02323051
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    Microbore columns in quantitative column liquid chromatography (1984)
    Springer
    Chromatographia 18 (1984), S. 574-578 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore column ; Flow rate stability ; Performance ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Some quantitative implications of the use of microbore columns in column liquid chromatography are investigated. Although for several pumps the flow rate stability at 50 μl min−1 is slightly worse than that of pumps operating at 1 ml min−1, the quantitative performance with respect to repeatability and reproducibility of response factors equals that of conventional liquid chromatography. Thermostatting is strongly recommended for microbore column operation.
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    URL: http://dx.doi.org/10.1007/BF02265697
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    High-speed assay of amino acids using reversed-phase liquid chromatography (1984)
    Springer
    Chromatographia 18 (1984), S. 62-64 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Microparticulate packing ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A procedure is described by which 20 commonly occurring amino acids may be separated by reversed-phase liquid chromatography at room temperature in a total time, including derivatisation with o-phthalaldehyde/2-mercaptoethanol reagent, of approximately 15 minutes. Further, an increase in column temperature enables increased resolution of certain amino acids to be obtained with small but acceptable losses in fluorescence intensity. The only major drawback to the method is that the derivatisation reagent does not react with proline or hydroxyproline.
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    URL: http://dx.doi.org/10.1007/BF02268457
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    Ion pair chromatography: A new approach to dynamic equilibrium (1984)
    Springer
    Chromatographia 18 (1984), S. 15-17 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair ; Dynamic equillibrium ; Aqueous and aqueous alcohol eluents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This work describes the dynamic equilibrium of an ionpair, reverse-phase liquid chromatography system. A given adsorbed quantity of an anionic surfactant can lead to different capacity factors and selectivity for anionic solutes.
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    URL: http://dx.doi.org/10.1007/BF02279456
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    Correlation of the retention data of polyaromatic hydrocarbons obtained on various stationary phases used in normal- and reversed-phase liquid chromatography (1984)
    Springer
    Chromatographia 18 (1984), S. 44-46 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention correlation ; Silica ; Normal and reversed phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The correlation between the retention data of polyaromatic hydrocarbons (PAH) obtained in normal-and reversed-phase liquid chromatography is investigated in order to determine the dominant factors controlling the retention. It is clear that the separation of PAHs on various chemically-bonded packing materials in normal- and/or reversed-phase modes is primarily controlled by the molecular structure and shape. The π-electron interaction between the solute and the stationary phase also contributes to the retention, although pure silica shows a somewhat different behavior.
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    URL: http://dx.doi.org/10.1007/BF02279465
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    High-performance liquid chromatography of sugars on copper (II) modified silica gel (1984)
    Springer
    Chromatographia 18 (1984), S. 600-602 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sugars ; Copper (II) complex ; UV detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive method of sugar analysis by HPLC is described in which a copper (II) modified silica gel as stationary phase is used. Detection is based on UV absorption of a complex formed between the sugar, copper, and ammonia.
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    URL: http://dx.doi.org/10.1007/BF02261971
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    An investigation into the use of semi-microbore reverse-phase 3 μm columns in HPLC (1984)
    Springer
    Chromatographia 18 (1984), S. 695-697 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Semi-microbore columns ; Reverse-phase ; 3 μm packing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation and use of semi-microbore (2mm i.d.), reverse-phase columns in HPLC has been investigated and they have been compared with 5 mm bore analytical columns. Injection valve design, detector cell volume, column loading and column linking are considered for both semi-microbore and analytical systems. Mobile phase flow-rate, detector time constant and column lifetime are also evaluated for small-bore systems.
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    URL: http://dx.doi.org/10.1007/BF02265817
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    Quantitative determination of trace amounts of L-alanine in triglycine sulphate crystals by HPLC (1984)
    Springer
    Chromatographia 18 (1984), S. 701-703 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Quantitative determination of L-alanine ; DABS-Cl ; Tryglycine sulphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the quantitative determination of L-alanine in triglycine sulphate crystals, in the presence of excess amounts of glycine, is described. L-alanine is determined after derivatization with 4-N,N-dimethyl-aminoazobenzene-4′-sulfonyl chloride (DABS-Cl) and in the presence of DABS-valine used as the internal standard. The results obtained indicate that the method permits the determination of alanine in triglycine sulphate crystals at concentrations of about 1%.
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    URL: http://dx.doi.org/10.1007/BF02265819
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    Packing and performance of microbore columns for adsorption and partition chromatography (1984)
    Springer
    Chromatographia 18 (1984), S. 73-80 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore columns ; Performance ; High-speed separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Microbore columns of 1 mm i.d. have turned out to be very suitable for the achievement of efficient columns. The packing procedure for stainless steel 1 mm i.d. columns from 5 to 100 cm in length was studied. Stationary phases used were: pure silica gel, octyl, octadecyl and amino bonded silicas. The main parameters (slurry composition, packing system, choice of materials) are discussed. Short columns packed with 3 or 5μm particles allow high speed separations. A separation in 18 seconds is described. Very high plate numbers can be obtained with long columns. With 7–8μm particles, a 1 m column can produce 50,000 plates (h=3). Columns can be joined without loss of efficiency. 270 000 theoretical plates were obtained on a 6 m adsorption column with a test mixture. In reversed-phase chromatography, bile acid sodium salts can be separated on a 1 m column. In adsorption chromatography, details are given of the separation of a polystyrene oligomer sample, as well as a light and a heavy petroleum distillate samples on a 2 m column with refractive index detection in the last-case.
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    URL: http://dx.doi.org/10.1007/BF02268460
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    The evaluation of “reversed phase” high-performance liquid chromatography packing materials (1984)
    Springer
    Chromatographia 18 (1984), S. 84-86 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Stationary phase evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the evaluation of reversed phase packing materials a mixture of acetylacetone, I-nitronaphthalene and naphthalene is proposed. This will reveal the usual optimum kinetic chromatographic parameters (the naphthalene peak), the degree of activity or endcapping status of the column (the ratio of the I-nitronaphthalene and naphthalene retention times) and trace metal activity (the shape and intensity of the acetylacetone peak).
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    A simple test to characterise C8/C18-bonded phases, particularly for toxicological screening (1984)
    Springer
    Chromatographia 18 (1984), S. 81-83 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded phases ; Characterisation ; Toxicological screening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes a test (“DMD-test”) to determine chromatographic properties of C8- or C18-bonded phases. The test was developed to select HPLC columns, for clinical and forensic toxicological screening in particular. The three compounds for the DMD-test are: diphenhydramine, 5-(p-methylphenyl)-5-phenylhydantoin (=MPPH) and diazepam. The isocratic mobile phase (acetonitrile/buffer pH2.3) is suitable for analysis of biological samples. 24 commercially available columns were tested. From our work this test enables the selection of commercial HPLC columns with reproducible properties. In this way a reference LC retention list can be developed to identify analytical results on an inter- or intralaboratory basis.
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    URL: http://dx.doi.org/10.1007/BF02268461
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    Retention prediction of substituted benzenes in reversed-phase HPLC (1984)
    Springer
    Chromatographia 18 (1984), S. 90-95 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Retention prediction ; Substituted benzenes ; Molecular parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of substituted benzene derivaties on a reversed-phase C-18 column has been examined. The correlations between the logarithm of the capacity factor and several descriptors indicating the molecular size, shape and the physical properties of a solute were determined. The results indicated that hydrophobicity is the dominant factor to control the retention of substituted benzenes. Their retention in reversed-phase HPLC can be predicted with help of the equations derived by multicombination of the parameters.
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    URL: http://dx.doi.org/10.1007/BF02268464
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    Air-sampling of aldehydes—Application to chromatographic determination of formaldehyde and acetaldehyde (1984)
    Springer
    Chromatographia 18 (1984), S. 137-144 
    Details
    ISSN: 1612-1112
    Keywords: Aldehydes and ketones ; 2,4-dinitrophenylhydrazine-coated silica gel ; Gas chromatography ; Column liquid chromatography ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary After a brief review of several methods described in the literature this paper discusses air-sampling on 2,4-dinitrophenylhydrazine-coated silica gel and identification requirements for aldehydes and ketones most commonly found in industrial pollution. Quantitative analysis of formaldehyde and acetaldehyde either by GC or by HPLC techniques is established using a dynamic system producing test atmospheres and compared with the usual colorimetric determinations.
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    URL: http://dx.doi.org/10.1007/BF02258770
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