bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro phamacology of MK‐996, a new potent and selective angiotensin II (AT1) receptor antagonist
Authors: Chang Raymond S. L. , Bendesky Robert J. , Chen Tsing‐B. , Faust Kristie A. , Kling Paul J. , O'Malley Stacey A. , Naylor Elizabeth M. , Chakravarty Prasun K. , Patchett Arthur A. , Greenlee William J. , Clineschmidt Bradley V. , Lotti Victor J. 
Published: January 2005

AbstractMK‐996 (N‐((4′‐((5,7‐Dimethyl‐2‐ethyl‐3H‐imidazo[4,5‐b]pyridin‐3‐yl)methyl) (1,1′‐biphenyl)‐2‐yl) sulfonylbenzamide) interacted in a competitive manner with rabbit aortic angiotensin II (All) receptors as determined by Scatchard analysis of specific binding of [125l]‐Sar1lle8‐All. MK‐996 also exhibited high affinity at All receptors in several tissues from different animal species (Ki = 0.1–0.4 nM). In vitro functional assays utilizing All‐induced aldosterone release in rat adrenal cortical cells demonstrated further that MK‐996 acts as a competitive, high affinity antagonist of All (pA2 = 10.3) and lacks agonist activity. MK‐996 also potently inhibited All‐induced contractile response in isolated rabbit aorta and pulmonary artery with a reduction in maximal response. The specificity of MK‐996 for All receptors was demonstrated by its lack of activity (IC50> 1 μM) in several other receptor binding assays and its inability to affect in vitro functional responses produced by other agonists. MK‐996 demonstrated a very high selectivity for the AT1 compared to AT2 receptor subtype (AT2 IC50 ≥ 2 μM). Direct binding studies using [3H]‐MK‐996 in rat adrenal indicated specific binding of [3H]‐MK‐996 is saturable and of high affinity (Kd = 0.47 nM). The specific [3H]‐MK‐996 binding in rat adrenal represents binding to pharmacologically relevant AT1 receptors as demonstrated by the similar Ki values for various All agonists and antagonists in inhibiting specific 3H‐MK‐996 and [125l]‐All binding to AT1 receptors. Dissociation rate studies of specific [3H]‐MK‐996 binding indicated a t1/2 of 103 min. This slow dissociation may account for the reduction in maximal responses to All in MK‐996 treated isolated blood vessels.
Models used to assess cardiovascular function in general pharmacology
Authors: Bunting Patricia B. , Siegl Peter K. S. 
Published: January 2005

AbstractIn the drug developmental process, information obtained from General Pharmacology assays plays an integral part in determining the future direction of the development. The evaluation of a drug in models of cardiovascular function can provide crucial data on cardiovascular activity unrelated to the drug's principal pharmacological action. These data can guide decision‐making steps in safety assessment and clinical studies and address problematic issues from regulatory agencies. While in‐depth protocols are necessary at times, in most instances examination of basic cardiovascular parameters (e.g., blood pressure, heart rate, and electrocardiogram) as well as evaluation of cardiovascular responses to selected autonomic nervous system stimulants, will reveal unpredicted pharmacological activities altering cardiovascular function and provide insight into mechanism of action. Through careful design of an appropriate protocol and animal model, detection of undesired cardiovascular activity can be simply and efficiently achieved.
Direct effects of indorenate and 8‐OH‐DPAT on the blood pressure of pithed rats
Authors: Castillo Carlos , Ibarra Maximiliano , Terron Jósé A. , Villalón Carlos M. , Hong Enrique 
Published: January 2005

AbstractIndorenate is a 5‐HT1A receptor agonist with antihypertensive properties. This study was aimed to determine if indorenate, like other 5‐HT1A receptor agonists, may also interact with α‐adrenoceptors. Therefore, the effects of indorenate and 8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (8‐OH‐DPAT; which has affinity for 5‐HT1A receptors and, to a lesser extent, for α1‐adrenoceptors) on the blood pressure of pithed rats were compared. Both compounds produced dose‐dependent increases in blood pressure; 8‐OH‐DPAT was the most potent whereas indorenate produced a higher maximum effect. Metitepine (a mixed 5‐HT1/5‐HT2 receptor antagonist), but not pindolol (a β‐adrenoceptor and 5‐HT1 receptor blocker), antagonized the pressor responses produced by both agonists; only the pressor effects of 8‐OH‐DPAT, however, were antagonized by prazosin (an α1‐adrenoceptor antagonist). Interestingly, ketanserin (a 5‐HT2 and α1‐adrenoceptor blocker) strongly antagonized the pressor responses to indorenate whereas only a slight inhibition of 8‐OH‐DPAT responses was observed. Further, in pithed rats intravenously infused with norepinephrine (NE), 8‐OH‐DPAT, but not indorenate, produced dose‐dependent hypotensive effects and both compounds were inactive in rats infused with quipazine. In conclusion, 8‐OH‐DPAT behaved as a partial agonist at α1‐adrenoceptors whereas indorenate produced pressor effects probably due to stimulation of 5‐HT2 receptors. Thus, 8‐OH‐DPAT, but not indorenate, showed activity at α1‐adrenoceptors in the pithed rat. © 1994 Wiley‐Liss, Inc.
Bacteriophage display: Peptide libraries and drug discovery
Authors: Winter Jill 
Published: January 2005

AbstractFilamentous bacteriophage can be utilized to display random peptides, cassette mutagenized proteins, or antibodies. Complex bacteriophage display libraries are easily synthesized and screened for binding to target molecules. Target binding bacteriophage are isolated by affinity selection and then amplified via infection of Escherichia coli. After several rounds of enrichment and amplication, the identity of the peptides, cassettes, or antibodies that bind to the target is readily obtained by DNA sequence analysis. This technology has introduced a new dimension to drug screening in that it offers easy access to a large sequence space. The goal of this review is to summarize technological advances and applications of the bacteriophage display systems. © 1994 Wiley‐Less, Inc.
Using in vitro nucleic acid selections for conventional drug design
Authors: Ellington Andrew D. 
Published: January 2005

AbstractIn vitro selection of nucleic acids has typically been used for the generation of high molecular weight inhibitors of enzymes. However, this technique can also be used for more conventional drug design in several different ways. First, the binding sites of regulatory proteins on DNA or RNA can be precisely delimited using in vitro selection. Second, “artificial” phylogenices generated by this technique can be used to model the three‐dimensional structure of nucleic acids. And, finally, the technique can be used to screen large chemical libraries for new lexitropsins, compounds that can specifically recognize nucleic acid sequence or structure. © 1994 Wiley‐Less, Inc.
Calcium channels: Structure, function, and classification
Authors: Perez‐Reyes Edward , Schneider Toni 
Published: January 2005

AbstractVoltage‐gated Ca2+ channels have been extensively characterized in terms of their electrophysiological and pharmacological properties [McDonald et al. (1994): Physiol Rev 74:365–507; Spedding and Paoletti (1992): Pharmacol Rev 44:363–376; Tsien and Tsien (1990): Annu Rev Cell Biol 6:715–760]. These studies indicate that there are numerous types of Ca2+ channels, termed L, N, P/Q, R, and T [Zhang et al. (1993): Neuropharmacology 32:1075–1088]. Biochemical and molecular biological studies have established that Ca2+ channels are multi‐subunit complexes composed of an ion‐conducting subunit, α1 (see Fig. 1), and smaller accessory subunits (α2, β, and sometimes γ and a 95 kDa protein). To date (May, 1994), genes for six α1, four β, one α2, and one γ have been cloned. Expression studies with cloned α1 have demonstrated that this subunit can determine the voltage and pharmacological sensitivity of the channel. This should allow us to classify the cloned α1s in terms of their type. Unfortunately life is not that simple. We will review how the accessory subunits are capable of modifying the pharmacological and biophysical characteristics of the channel. Despite these complications, 5 of the 6 α1s can be classified as follows: (1) three α1s (α1s, α1c, and α1D) belong to the L‐type (dihydropyridine‐sensitive), (2) α1B is an N‐type (ω‐conotoxin‐GVIA‐sensitive), and (3) α1A is a P (ω‐aga‐IVA‐sensitive, also called Q [see Zhang et al. (1993): Neuro‐pharmacology 32:1075–1088], herein referred to as P/Q). The sixth α1, α1E, does not display any distinctive pharmacology, thus it has been called an R‐type (resistant). The molecular biology of Ca2+ channels has its origins in the biochemical characterization of the skeletal muscle dihydropyridine receptor. This receptor/channel complex was purified, sequenced, cloned, and expressed. Cloning of these cDNAs provided the probes to discover the molecular diversity of Ca2+ channels. We will review the cloning, tissue distribution, and functional expression of α1 subunits following a historical path, then review the accessory subunits. © 1994 Wiley‐Liss, Inc.
Effects of GS 386, a novel dihydroisoquinoline compound, on rabbit atrial myocytes and rat aorta
Authors: Chang Ki Churl , Park Choon Ok , Hong Seong Geun 
Published: January 2005

AbstractThe effects of GS 386, a novel benzylisoquinoline derivative, on Ca2+ current and vasodilatation were investigated using the single rabbit atrial myocyte and rat thoracic aorta preparations. In rabbit myocytes, the Ca2+ current was recorded during various depolarizations for 200 ms from a holding potential of −40 mV using the whole patch‐clamp technique. Superfusion of GS 386 led to a reduction of the Ca2+ current amplitude concentration‐dependently, in which the IC50 value was 0.25 μM. However, the dependence of the Ca2+ current on the membrane potential was not altered by GS 386. In rat aorta, GS 386 inhibited high K+‐induced contractions more strongly than that induced by phenylephrine. These results indicate that GS 386 has Ca2+ antagonistic actions in rat aorta and rabbit heart. © 1994 Wiley‐Liss, Inc.
Attenuation of in vivo and in vitro seizure activity using the adenosine agonist, metrifudil
Authors: Krahl Scott E. , Treas Loraine M. , Castle James D. , Berman Robert F. 
Published: January 2005

AbstractAdenosine and other adenosine receptor agonists have been shown to inhibit seizures in a variety of in vivo and in vitro models. In the present study, the anticonvulsive effects of the partially selective A2a agonist, N‐[(2‐methylphenyl)methyl]‐adenosine (metrifudil), were examined using both the amygdala kindling and 0‐Mg++‐induced bursting hippocampal slice seizure models. Fully amygdala‐kindled rats were injected with 1, 10, or 25 mg/kg (2.7, 27.0, or 67.4 μmol/kg) ip metrifudil, or vehicle (dimethyl sulfoxide), 20 min prior to receiving the kindling stimulus. Metrifudil significantly reduced after‐discharge duration in a dose‐related fashion compared to vehicle injections. After‐discharge threshold and behavioral seizure stage were not significantly affected. In the in vitro hippocampal slice preparation, stimulation of Schaffer collateral axons under 0‐Mg++ conditions resulted in spontaneous and evoked epileptiform burst activity in the CA1 region. The addition of 1, 10, or 100 μM metrifudil to the 0‐Mg++ media abolished this epileptiform activity in a concentration‐related fashion. These findings indicate that the adenosine agonist, metrifudil, may have anticonvulsive properties, and are in support of the premise that the adenosine system plays an anticonvulsive role in the central nervous system. © Wiley‐Liss, Inc.
Modulation of the discriminative stimulus properties of (−)‐nicotine by diazepam and ethanol
Authors: Kim David J. B. , Brioni Jorge D. 
Published: January 2005

AbstractThe effect of different ligands for the GABA‐BZD receptor and the NMDA receptor were studied in rats trained to discriminate (−)‐nicotine (1.9 μmol/kg) from saline in a standard two‐bar operant conditioning paradigm with food reinforcement. MK‐801 (0.03–0.3 μmol/kg), flumazenil (10–30 μmol/kg), and Ro 15–4513 (3–10 μmol/kg) did not generalize to (−)‐nicotine on nicotine‐trained rats, and when tested as antagonists they did not block the nicotine cue. Diazepam (3–10 μmol/kg) and ethanol (11–22 mmol/kg) did not have any effect by themselves, but they significantly attenuated the nicotine cue by 53 and 65%, respectively, without affecting the response rates of the animals. Pre‐treatment with flumazenil (30 μmol/kg) reversed the effect of diazepam but it did not reverse the effect of ethanol on the discriminative stimulus properties of (−)‐nicotine. The effect of ethanol was not blocked by Ro 15–4513 (10 μmol/kg). These data indicate that diazepam and ethanol modulate the expression of the nicotine cue and that the effect of diazepam is mediated via a benzodiazepine receptor mechanism. © Wiley‐Liss, Inc.
Pharmacological characterization of enantiomers of 8‐thiomethyl‐2‐(di‐n‐propylamino)tetralin, potent and selective 5‐HT1Areceptor agonists
Authors: Foreman Mark M. , Fuller Ray W. , Leander J. David , Nelson David L. , Calligaro David O. , Lucaites Virginia L. , Wong David T. , Zhang L. , Barrett James E. , Schaus John M. 
Published: January 2005

AbstractLY274600 and LY274601 are the S (−) and R (+) enantiomers, respectively, of 8‐thiomethyl‐2‐(di‐n‐propylamino)tetralin (8‐OH‐DPAT). In in vitro studies, both enantiomers have high and selective affinity for the 5‐HT1Areceptor. However, LY274600 produced submaximal inhibition of forskolin‐stimulated cyclase activity, which indicates that it is a partial agonist, whereas LY274601 produced maximal inhibition of cyclase activity, which indicates that it is a full agonist in this model. Both of these enantiomers had potent in vivo pharmacological effects in rats that are characteristic of 5‐HT1Areceptor agonists including (1) a reduction of hypothalamic 5‐HIAA levels, (2) an increase in serum corticosterone levels, (3) a reduction in hypothalamic 5‐HTP accumulation after decarboxylase inhibition, (4) an induction of 5‐HT1Abehavioral responses, e.g., flat posture and lower lip retraction, and (5) a lowering of body temperature. In these general pharmacological tests, both compounds had a potency equal to or greater than 8‐OH‐DPAT but had a greater oral activity. LY274601 appeared to be either slightly more potent or efficacious than LY274600. In the drug‐discrimination studies using pigeons trained to identify the effects of 8‐OH‐DPAT, LY274601 was significantly more potent than LY274600, but both were less potent than 8‐OH‐DPAT. Both enantiomers restored full sexual reflex function to rats that had reduced sexual capacity. In rats with normal capacity for sexual reflexes but reduced performance, the enantiomers caused decreases in ejaculatory latencies and postejaculatory latencies and increases in copulatory efficiency and rate. No consistent differences between the enantiomers could be demonstrated in these estimates of total sexual performance, erectile capacity, and sexual drive. Both enantiomers increased punished responding at lower doses than were needed to decrease unpunished responding in pigeons, an effect that is indicative of anxiolytic activity. LY274600, a partial agonist, produced a significantly greater change in punished responding than did LY274601, a full agonist. Both compounds induced dose‐related decreases in immobility time and defecation rate in the rat forced swim model, which represent reductions in stress‐induced “behavioral despair” and stress‐induced gastrointestinal motility. Collectively, these pharmacological studies have shown that the substitution of a thiomethyl for hydroxyl group at the 8 position on the 2‐(di‐n‐propylamino) tetralin structure resulted in selective and potent agonists for the 5‐HT1Areceptor similar to that of 8‐OH‐DPAT but with improved oral potency. The preclinical efficacy studies demonstrated possible utilites for these compounds in the treatement of either sexual response disorders, anxiety, or depression. © 1995 Wiley‐Liss, Inc.
Detection of apoptosis‐associated DNA fragmentation using a rapid and quantitative filter elution assay
Authors: Bertrand Richard , Kohn Kurt W. , Solary Eric , Pommier Yves 
Published: January 2005

AbstractDNA degradation to oligonucleosome size fragments is one of the cellular markers of apoptosis. Based on DNA filter elution methodology, we have designed a simple assay to monitor apoptosis‐associated DNA fragmentation from cultured cells or from a reconstituted cell‐free system. The cells are prelabeled with [14C]‐thymidine for one cell cycle and chased in nonradioactive medium for a few hours in order to allow incorporation of the radiolabeled thymidine in high molecular weight DNA. After the apoptosis‐inducing treatment, cells (or subcellular fractions of the cell‐free system) are deposited onto a protein‐adsorbant filter and washed with physiological saline. Lysis is then performed with a mild detergent (sarkosyl) and 2 M salt. The lysis fraction is collected, counted, and computed to calculate the fraction of DNA in the lysis fraction. In normal cells more than 90% of the DNA remains on the filter, while in apoptotic cells the kinetics of DNA fragmentation can be monitored and more than 80% of the counts can be found in the lysis. The DNA filter elution assay is sensitive, quantitative, and rapid. By using different types of filters and lysis solution (± proteinase), the protein‐bonding to the DNA fragments can be determined. Some applications of this assay to study the effects and mechanisms of action of new therapeutic drugs are presented and discussed. © 1995 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Antibody‐directed enzyme prodrug therapy: A review
Authors: Bagshawe Kenneth D. 
Published: January 2005

AbstractMany of the limitations of conventional cytotoxic chemotherapy and of attempts to achieve selectivity using antibody vectors can be overcome by a 2 or 3 stage prodrug system. An antibody vectors to tumour sites an enzyme that is not normally present in human extracellular fluids. The tumour located enzyme activates a subsequently administered prodrug. As with other antibody based systems the pharmacokinetics and biodistribution of the antibody‐enzyme conjugate are critical elements. In contrast to antibody drug conjugates and radiolabelled antibodies, an enzyme can be inactivated in non‐tumour tissues, or subjected to rapid clearance, without toxic effects, which allows high tumour to normal tissue ratios to be achieved. Enzymes conjugated to antibodies increase the problem of immunogenicity and require either the use of immunosuppressive agents, or the development of non‐immunogenic catalysts. A small scale pilot clinical trial has shown the general feasibility of the approach. © 1995 Wiley‐Liss, Inc.
Pharmacology of the human metabolites of dolasetron, an antiemetic 5‐HT3 receptor antagonist
Authors: Bigaud Marc , Elands Jack , Kastner Philip R. , Bohnke Rick A. , Emmert Lee W. , Galvan Martin 
Published: January 2005

AbstractDolasetron mesylate (MDL 73, 147EF) is a novel 5‐HT3 receptor antagonist under development as an anti‐emetic. Dolasetron undergoes rapid and extensive metabolism to form a major metabolite, MDL 74,156; the metabolism is stereoselective, with the [+]‐enantiomer (MDL 73,405) predominant. MDL 74,156 is also hydroxylated to form MDL 102, 382 (5′‐OH metabolite) and MDL 73,492 (6′‐OH metabolite). The present study evaluated the pharmacological properties of dolasetron and its human metabolites in vitro and following oral and intravenous administration in rats and compared the antiemetic effects of dolasetron and ondansetron in dogs. Each of the metabolites had high affinity at and was selective for 5‐HT3 receptors. In anesthetized rats, the 5‐HT‐mediated von Bezold‐Jarisch reflex was inhibited by 1 mg/kg oral doses of either dolasetron (3.1 μmol/kg), ondansetron (3.4 μmol/kg), granisetron (3.2 μmol/kg), or tropisetron (3.5 μmol/kg) and by intravenous doses of dolasetron and ondansetron. Dolasetron had a significantly longer duration of action than ondansetron. In addition, the metabolites MDL 73,405, MDL 102,382, and MDL 73,492 exhibited significant 5‐HT3 receptor antagonist activity following intravenous administration, but only MDL 73,405 exhibited significant activity following oral administration. Both dolasetron mesylate and ondansetron reduced the number of emetic episodes and increased the time to first emetic event in cisplatin‐treated dogs. The clinical effects and duration of action observed following administration of dolasetron mesylate to humans are likely due mainly to MDL 73,405 (the [+]‐enantiomer of MDL 74,156). © 1995 Wiley‐Liss, Inc.
Olanzapine moderately increases conflict responding but does not produce a benzodiazepine‐like cue in rat
Authors: Nanry Kevin P. , Pollard Gerald T. , Howard James L. 
Published: January 2005

AbstractIn rats pressing a lever for food on a Geller‐Seifter conflict schedule with incremental electrical stimulus, the putative novel antipsychotic olanzapine (0.78 and 1.56 mg/kg po) increased conflict responding by 35% (half the maximal increase produced by chlordiazepoxide). In rats trained to discriminate between chlordiazepoxide and saline, olanzapine (0.19–1.56 mg/kg po) reduced response rate dose‐dependently; all rats chose the saline‐appropriate lever at all doses. The results replicate the moderate anticonflict effect of olanzapine and show that the subjective cue differs from that of a benzodiazepine. A possible anxiolytic action of this class of antipsychotics is proposed. © 1995 Wiley‐Liss, Inc.
Approach to the discovery of novel, selective inhibitors of p56lck tyrosine kinase: Identification of non‐hydroxylated chromones as p56lck inhibitors
Authors: Miller Deborah , Wang Su , Reid John , Xie Wen , Gauvin Bruce , Kelley Marian , Sarup Jay , Sawutz David G. , Miski Muhmut , Dolle Roland E. , Faltynek Connie R. 
Published: January 2005

AbstractThe protein tyrosine kinase p56Ick, which is expressed predominantly in lymphocytes, plays a critical role in optimal T cell activation through the T cell antigen receptor. An approach is presented for the discovery of selective p56Ick inhibitors, which are potential immunosuppressants. A non‐radioactive assay for p56Ick tyrosine kinase activity has been developed and adapted for high volume screening. This assay does not require purified enzyme. p56Ick in the plasma membranes of a human T cell line is purified in situ by immobilization onto the wells of a microtiter plate using an antibody specific for p56Ick. Following the kinase reaction in the presence of test compound, autophosphorylated p56Ick is detected with a biotinylated monoclonal antibody to phosphotyrosine. Using the approach described in this report, three simple chromones have been identified that inhibit p56Ick autophosphorylation with low micromolar potencies and exhibit some selectivity for p56Ick over the serine/threonine and other tyrosine kinases tested. These compounds constitute a novel group of p56Ick tyrosine kinase inhibitors. ©1995 Wiley‐Liss, Inc.