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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Levels of total RNA, total DNA, 18S ribosomal RNA (rRNA), poly(A) messenger RNA (mRNA), and two mRNAs coding for abundant myofibrillar proteins were estimated in laboratory-reared Atlantic cod larvae (Gadusmorhua Linnaeus) under conditions of feeding and starvation. DNA probes specific for cod 18S rRNA, β-actin mRNA and myosin heavy chain mRNA were developed. In two experiments on newly hatched larvae in fed and starved treatments, changes in 18S rRNA and mRNA were similar to changes in total RNA during the first weeks after hatching. RNA levels in fed and starved larvae in both experiments were stable, or increased, over the first 3 d after hatching, and then decreased to minima at 9 d. RNA levels increased after 9 d, with the degree and timing of the increase varying among the individual classes of RNA. Complete mortality of starved larvae in both experiments was observed shortly after 11 d, corresponding to exhaustion of endogenous yolk reserves. Total RNA content, RNA/DNA ratio, 18S rRNA levels, total mRNA pool, and actin and myosin heavy chain mRNA levels showed significant differences in fed and starved first-feeding larvae after yolk exhaustion. In another experiment with 3- to 4-week-old cod larvae, 18S rRNA levels were significantly lower in starved versus fed larvae after 3 d. Total RNA responded to feeding and starvation within a similar time as 18S rRNA and the mRNAs examined. Analysis of bulk nucleic acids using fluorometric dyes was simpler and faster than analysis of individual RNAs using hybridization probes, and provides valuable information on recent growth and condition of individual larvae. However, analysis of specific RNAs can provide information on expression of the corresponding genes and reveal the changes underlying trends seen in bulk RNA.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 13 (1978), S. 373-378 
    ISSN: 1432-1041
    Keywords: Pharmacokinetic model ; plasma protein binding ; apparent volume of distribution ; tolbutamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A pharmacokinetic model that incorporates linear binding of drug to plasma proteins and tissue indicates the same relationship between apparent volume of distribution and drug binding as that proposed by Gillette (1971) based on a simple distribution model. Apparent volume of distribution (V) is directly proportional to free fraction of drug in plasma (fp) and indirectly proportional to free fraction of drug in tissue (fT). In the case of a constant fT, a plot of V versus fp will be linear with an intercept equal to plasma volume (Vp). If fT changes with fp, an apparently linear plot may result but the intercept will exceed Vp. An approach to the calculation of fT, a composite binding parameter, is presented and illustrated by comparing the tissue binding of tolbutamide in patients during acute viral hepatitis and upon recovery.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 22 (1982), S. 71-75 
    ISSN: 1432-1041
    Keywords: cephalosporin ; ceftriaxone ; protein binding ; non-linear pharmacokinetics ; intravenous injection ; plasma levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetic parameters of total (bound and unbound) and free (unbound) ceftriaxone in six healthy volunteers after intravenous injection of 39 were compared with low-dose data from a previous study. The dose-dependent behaviour of total drug was considerably more pronounced after the 3 gram dose. In contrast, total body clearance (Cl S F =258 ml/min), renal clearance (Cl R F =170 ml/min) and volume of distribution (V D(β) F =168 l) of free (unbound) drug did not differ from the data reported earlier. There was no significant change in biological half-life (t1/2(β)=7.8 h) or in the fraction excreted unchanged in urine (fu=0.67).
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 34 (1988), S. 151-156 
    ISSN: 1432-1041
    Keywords: ceftriaxone ; probenecid ; drug interaction ; protein binding ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The kinetics and binding parameters of ceftriaxone have been characterized in eight normal subjects who received, in sequence, 1.0 g ceftriaxone and 1.0 g ceftriaxone together with 250 and 500 mg probenecid q.i.d. Probenecid increased the total systemic clearance (CL S T ) from 0.244 to 0.312 ml/min/kg, whereas the terminal half-life (t 1/2(β) T ) fell from 8.1 to 6.5 h. In contrast, the renal clearance of free ceftriaxone (CL R F ) was decreased from 2.09 to 1.67 ml/min/kg, confirming a small but significant contribution of tubular secretion to the renal elimination of ceftriaxone. The final value of CL R F was attained with the lower dose probenecid, whereas the non-renal clearance of free ceftriaxone (CL NR F ) fell progressively from 2.78 to 1.90 ml/min/kg with the increasing probenecid dose. The total decrease in the systemic clearance of free ceftriaxone (CL S F ) after the higher dose of probenecid was about 30% (4.87 to 3.57 ml/min/kg). As a consequence of a decreased affinity constant (KA), the average free fraction in plasma (f) was increased by 54% after the low dose and by 74% after the high dose of probenecid. The protein binding interaction between probenecid and ceftriaxone appears to be unique. The results are of limited clinical consequence for ceftriaxone but they emphasise the importance of evaluating the kinetics of the free drug when examining interactions involving probenecid.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 25 (1983), S. 399-405 
    ISSN: 1432-1041
    Keywords: ceftriaxone ; pharmacokinetics ; concentration-dependent binding ; volume of distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have theoretically examined the influence of plasma protein binding (specifically the fraction unbound, fp) on the pharmacokinetic parameters following rapid injection of a drug undergoing concentration-dependent binding. Particular emphasis was placed on the apparent volume of distribution terms based on both total and unbound drug concentrations. Computer simulations were performed to establish the validity and utility of such relationships. The following observations were made: a) distributional parameters based on total drug (both Vβ and the model-independent VSS) were inaccurate/invalid; b) V β based on unbound drug was misleading; c) the model-independent VSS for unbound drug accurately predicted the steady state situation. Furthermore, two new terms ( $$\bar f_P $$ and $$\bar V_{SS}^T $$ ) were introduced which provide additional insight concerning the disposition of this type of drug. The $$\bar f_P $$ is the area-weighted average fraction unbound in the plasma and $$\bar V_{SS}^T $$ is the corrected steady state distribution term for total drug levels. The present study indicates that useful distributional and clearance terms can be calculated for this type of drug, provided that the time course of unbound drug as well as total drug can be followed. Moreover, guidelines for their extrapolation to steady state conditions and their correct interpretations are discussed.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 25 (1983), S. 407-412 
    ISSN: 1432-1041
    Keywords: ceftriaxone ; pharmacokinetics ; concentration-dependent binding ; volume of distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Guidelines presented previously for the analysis of plasma concentration versus time data for a drug exhibiting concentration-dependent plasma protein binding were successfully applied to the distributional parameters of a new cephalosporin, ceftriaxone. This approach provided several striking observations when the pharmacokinetics of ceftriaxone in a healthy and uremic population were re-examined. First, the parameter $$\bar f_P $$ converted the apparent dose-dependent distributional terms of ceftriaxone into a function of the concentration-dependent plasma protein binding. Second, a strong correlation between the term V SS U and the reciprocal of $$\bar f_P $$ was established within each of the two populations. While this $$\bar f_P $$ term accounted for the variability within the respective populations due to ceftriaxone-albumin binding differences, it did not account for all of the distributional differences between the two populations. The present analysis revealed that the altered physiologic state of uremia (larger plasma volumes and interstitial to intravascular albumin ratios), in addition to differences in plasma protein binding, dictated the distribution of ceftriaxone in healthy and uremic subjects. Furthermore, the binding-disposition model which accounts for the presence of plasma proteins outside the vascular space, was established to be appropriate in describing the distribution of ceftriaxone.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 67-68 (Jan. 1991), p. 79-84 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 32-33 (Jan. 1991), p. 219-224 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Brain and Language 42 (1992), S. 38-51 
    ISSN: 0093-934X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Linguistics and Literary Studies , Medicine , Psychology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Brain and Language 42 (1992), S. 431-453 
    ISSN: 0093-934X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Linguistics and Literary Studies , Medicine , Psychology
    Type of Medium: Electronic Resource
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