1.
Ackermann, Paul, et al.
(författare)
An opioid system in connective tissue : A study of Achilles tendon in the rat
2001
Ingår i: Journal of Histochemistry and Cytochemistry. - : SAGE Publications. - 0022-1554 .- 1551-5044. ; 49:11, s. 1387-1395
Tidskriftsartikel (refereegranskat) abstract
The occurrence of endogenous opioids and their receptors in rat achilles tendon was analyzed by immunohistochemistry (IHC), radioimmunoassay (RIA), and in vitro binding assays. The investigation focused on four enkephalins, dynorphin B, and nociceptin/orphanin FQ. Nerve fibers immunoreactive to all enkephalins (Met-enkephalin, Leu-enkephalin, Met-enkephalin-Arg-Gly-Lys, Met-enkephalin-Arg-Phe) were consistently found in the loose connective tissue and the paratenon, whereas dynorphin B and nociceptin/orphanin FQ could not be detected. The majority of enkephalin-positive nerve fibers exhibited varicosities predominantly seen in blood vessel walls. Measurable levels of Met-enkephalin-Arg-Phe and nociceptin/orphanin FQ were found in tendon tissue using RIA, whereas dynorphin B could not be detected. In addition to the endogenous opioids identified, delta -opioid receptors on nerve fibers were also detected by IHC. Binding assays to characterize the opioid binding sites showed that they were specific and saturable for [H-3]-naloxone (K-d 7.01 +/- 0.98 nM; B-max 23.52 +/- 2.23 fmol/mg protein). Our study demonstrates the occurrence of an opioid system in rat achilles tendon, which may be assumed to be present also in other connective tissues of the locomotor apparatus. This system may prove to be a useful target for pharmacological therapy in painful and inflammatory conditions by new drugs acting selectively in the periphery.
2.
Alterman, Mathias, et al.
(författare)
P1/P1' modified HIV protease inhibitors as tools in two new sensitive surface plasmon resonance biosensor screening assays
2001
Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 13:2, s. 203-212
Tidskriftsartikel (refereegranskat) abstract
The commonly used HIV-1 protease assays rely on measurements of the effect of inhibitions on the hydrolysis rate of synthetic peptides. Recently an assay based on surface plasmon resonance (SPR) was introduced. We have taken advantage of the fact that the SPR signal is proportional to the mass of the analyte interacting with the immobilised molecule and developed two new improved efficient competition assay methods. Thus, high molecular weight binders were used as amplifiers of the surface plasmon resonance signal. Linkers were attached by a Heck reaction to the para-positions of the P1/P1′ benzyloxy groups of a linear C2-symmetric C-terminal duplicated inhibitor to enable (a) biotin labelling or (b) direct immobilisation of the inhibitor to the biosensor surface matrix. The interaction properties of a series of 17 structurally diverse inhibitors was assessed and compared to previously reported data. The most sensitive assay was obtained by immobilising the enzyme and amplifying the signal with an antibody, giving a detection range between 0.1 nM and 10 μM. Immobilisation of the inhibitor resulted in a stable and durable surface but a narrower detection range (1–100 nM). The two competition assays are anticipated to be very suitable for fast screening of potential HIV inhibitors.
3.
Bouw, M. René, et al.
(författare)
Blood-brain barrier transport and brain distribution of morphine-6-glucuronide in relation to the antinociceptive effect in rats : pharmacokinetic/pharmacodynamic modelling
2001
Ingår i: British Journal of Pharmacology. - : The British Pharmacological Society. - 0007-1188 .- 1476-5381. ; 134:8, s. 1796-1804
Tidskriftsartikel (refereegranskat) abstract
1. The objective of this study was to investigate the contribution of the blood-brain barrier (BBB) transport to the delay in antinociceptive effect of morphine-6-glucuronide (M6G), and to study the equilibration of M6G in vivo across the BBB with microdialysis measuring unbound concentrations. 2. On two consecutive days, rats received an exponential infusion of M6G for 4 h aiming at a target concentration of 3000 ng ml(-1) (6.5 microM) in blood. Concentrations of unbound M6G were determined in brain extracellular fluid (ECF) and venous blood using microdialysis and in arterial blood by regular sampling. MD probes were calibrated in vivo using retrodialysis by drug prior to drug administration. 3. The half-life of M6G was 23+/-5 min in arterial blood, 26+/-10 min in venous blood and 58+/-17 min in brain ECF (P<0.05; brain vs blood). The BBB equilibration, expressed as the unbound steady-state concentration ratio, was 0.22+/-0.09, indicating active efflux in the BBB transport of M6G. A two-compartment model best described the brain distribution of M6G. The unbound volume of distribution was 0.20+/-0.02 ml g brain(-1). The concentration-antinociceptive effect relationships exhibited a clear hysteresis, resulting in an effect delay half-life of 103 min in relation to blood concentrations and a remaining effect delay half-life of 53 min in relation to brain ECF concentrations. 4. Half the effect delay of M6G can be explained by transport across the BBB, suggesting that the remaining effect delay of 53 min is a result of drug distribution within the brain tissue or rate-limiting mechanisms at the receptor level.
4.
Broussalis, Adriana M., et al.
(författare)
First cyclotide from Hybanthus (Violaceae)
2001
Ingår i: Phytochemistry. - : Elsevier. - 0031-9422 .- 1873-3700. ; 58:1, s. 47-51
Tidskriftsartikel (refereegranskat) abstract
Hypa A, a novel macrocyclic polypeptide containing 30 amino acid residues, has been isolated from the n-butanol extract of the Argentine plant Hybanthus parviflorus. The sequence, cyclo-(SCVYIPCTITALLGCSCKNKVCYNGIPCAE), was determined by automated Edman degradation, quantitative amino acid analysis and nanospray MS/MS2. Three intramolecular disulfide bridges stabilize the cyclic peptide backbone of hypa A. Using these structural features to classify the peptide as a cyclotide, we extended the distribution of that substance class to a new genus, and now propose a uniform nomenclature for cyclotides.
5.
6.
El-Seedi, Hesham R, et al.
(författare)
Ecologically active 2-octanoylcyclohexane-1,3-dione from Philodendron guttiferum
2001
Ingår i: Journal of Chemical Ecology. - 0098-0331 .- 1573-1561. ; 27:3, s. 517-521
Tidskriftsartikel (refereegranskat) abstract
The novel naturally occurring 2-octanoylcyclohexane-1,3-dione 1 was isolated in its enol form from P. guttiferum (Araceae). Its chemical ecological relevance is discussed. There was mass spectral evidence for the presence of small amounts of the homologous 2-decanoyl and 2-dodecanoyl derivatives.
7.
8.
Graffner-Nordberg, Malin, et al.
(författare)
Design, Synthesis, Computational Prediction and Biological Evaluation of Ester Soft Drugs as Inhibitors of Dihydrofolate Reductase from Pneumocystis Carinii
2001
Ingår i: Journal of Medicinal Chemistry. - : American Chemical Society (ACS). - 0022-2623 .- 1520-4804. ; 44:15, s. 2391-2402
Tidskriftsartikel (refereegranskat) abstract
A series of lipophilic soft drugs structurally related to the nonclassical dihydrofolate reductase (DHFR) inhibitors trimetrexate and piritrexim have been designed, synthesized, and evaluated in DHFR assays, with special emphasis on the inhibition of P. carinii DHFR. The best inhibitors, encompassing an ester bond in the bridge connecting the two aromatic systems, were approximately 10 times less potent than trimetrexate and piritrexim. The metabolites were designed to be poor inhibitors. Furthermore, molecular dynamics simulations of three ligands in complex with DHFR from Pneumocystis carinii and from the human enzyme were conducted in order to better understand the factors determining the selectivity. A correct ranking of the relative inhibition of DHFR was achieved utilizing the linear interaction energy method. The soft drugs are intended for local administration. One representative ester was selected for a pharmacokinetic study in rats where it was found to undergo fast metabolic degradation to the predicted inactive metabolites.
9.
Gupta, S, et al.
(författare)
In vitro evidence for auto-induction of artemisinin metabolism in the rat.
2001
Ingår i: European journal of drug metabolism and pharmacokinetics. - 0378-7966. ; 26:3, s. 173-8
Tidskriftsartikel (refereegranskat) abstract
Artemisinin disappearance rate was more rapid in incubations with liver microsomes from rats pre-treated with oral artemisinin (60 mg/kg/day for 5 days) compared with microsomes from control animals. A single pathway Michaelis-Menten saturable elimination model was fitted to the concentration-time data of artemisinin incubations by non-linear regression. Model parameters were obtained after fitting results for each animal separately and by pooling data for pre-treated and control animals. Parameter estimates (% coefficient of variation) from fitting the pooled data was maximum velocities (Vmax) = 1.8 (12) mmole/min/mg protein and Michaelis constants (Km) = 20(22) microM for artemisinin pre-treated and Vmax = 0.85 (35) mmole/min/mg protein and Km = 67(52) microM for control animals indicating a 2-fold increase in Vmax and a 3-fold decrease in Km with microsomes from artemisinin pre-treated animals. Estimates of intrinsic clearance in microsomes from the pre-treated animals were 8-fold higher compared with controls. Thus, artemisinin appears to be a potent auto-inducer of drug metabolism in rats as has also been observed in humans. The present findings suggest caution in the interpretation of repeat-dose rat toxicity studies with artemisinin unless its pharmacokinetics are simultaneously monitored, since during multiple administration, the exposure of the drug will not be constant over time.
10.
Hjälmås, Kelm, 1933, et al.
(författare)
The overactive bladder in children: a potential future indication for tolterodine.
2001
Ingår i: BJU international. - 1464-4096. ; 87:6, s. 569-74
Tidskriftsartikel (refereegranskat) abstract
OBJECTIVE: To determine the safety, efficacy and pharmacokinetics of tolterodine in children with an overactive bladder. PATIENTS AND METHODS: Thirty-three children (20 boys and 13 girls, aged 5-10 years) with an overactive bladder and symptoms of urgency, frequency and/or urge incontinence were enrolled in an open, dose-escalation study. Patients were treated with oral tolterodine 0.5 mg (n = 11), 1 mg (n = 10) or 2 mg (n = 12) twice daily for 14 days. The primary safety endpoint was the change in residual urinary volume, as determined by ultrasonography. In addition, voiding diary variables (frequency and incontinence episodes) and pharmacokinetics were evaluated. Other safety endpoints included laboratory variables, electrocardiogram recordings and reported adverse events. RESULTS: There were no safety concerns in terms of the change in residual urinary volume for any of the three dosage groups; values were comparable with baseline after 2 weeks of treatment for all three dosages. Adverse events were reported by 20 patients (six on 0.5 mg, five on 1 mg, and nine on 2 mg). Most adverse events were not considered to be drug-related; of the 13 possibly related events, 10 occurred in those taking 2 mg. Headache was the most commonly reported adverse event. No serious adverse events were reported and there were no general safety concerns. There was an improvement in voiding diary variables in all treatment groups after 2 weeks of treatment, although the efficacy was greatest in those taking 1 mg and 2 mg. Pharmacokinetic findings were consistent with dose linearity over the range 0.5-2 mg. CONCLUSION: The results support the use of 1 mg twice daily as the optimal dose of tolterodine for treating children aged 5-10 years with an overactive bladder.
