bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the nicotinic receptor loss in dementia using the nicotinic antagonist mecamylamine: Effects on human cognitive functioning
Authors: Newhouse Paul A. , Potter Alexandra , Corwin June , Lenox Robert
Published: January 2005

The loss of central nicotinic receptors is a neurochemical hallmark of several degenerative brain disorders, notably Alzheimer's disease (AD) and Parkinson's disease (PD). However, uncertainty has remained about the significance of this loss for the cognitive symptomatology of these disorders. Symptoms of impaired acquisition of information and short‐term storage, impaired memory consolidation, attention, visual perception, and speed may reflect nicotinic lesions. Administration of the nicotinic antagonist mecamylamine in young and elderly humans produces significant dose‐related impairment of new learning, liberalization of response bias, and slowing of reaction time. These results suggest that mecamylamine may in part model the results of nicotinic receptor loss in AD and that nicotinic augmentation of some aspects of cognitive functioning may be a worthwhile strategy to pursue, particularly if agents can be developed that are more selective than nicotine itself. © 1994 Wiley‐Liss, Inc.
Effects of nicotine on levels of acetylcholine and biogenic amines in rat cortex
Authors: Summers Kathleen L. , Cuadra Gabriel , Naritoku Dean , Giacobini Ezio
Published: January 2005

Transcortical dialysis was employed to investigate the effects of systemic nicotine (3.6 μmol/kg, sc) administration on cortical extracellular levels of acetylcholine (ACh), norepinephrine (NE), dopamine (DA), and serotonin (5‐HT). Systemic administration of [–]‐nicotine produced a 106% increase of cortical ACh release over basal levels that persisted for approximately 2 h. Concurrently, NE levels were increased 86% over basal values for 60 min. The effects appear to be stereoselective, as systemic injections of [+]‐nicotine significantly increased cortical ACh levels only 48% over basal levels for 30 min, and NE levels in the dialysate only 43% over control levels for 60 min. No significant changes of basal dopamine (DA) or serotonin (5‐HT) levels were observed, although DA did appear to increase in response to systemic nicotine. In addition, striatal total endogenous ACh increased significantly over control levels 15 min after [–]‐nicotine administration (3.6 μmol/kg, sc), and then significantly declined after 3 h, suggesting that nicotine may influence synthesis as well as release. Analysis of total ACh levels in cortical tissue revealed a similar trend. At the dose utilized in this study, no changes in the cortical electroencephalogram (EEG) were observed. © 1994 Wiley‐Liss, Inc.
Cytoprotective actions of 2,4‐dimethoxybenzylidene anabaseine in differentiated PC12 cells and septal cholinergic neurons
Authors: Martin Eileen J. , Panickar Kiran S. , King Michael A. , Deyrup Malgorzata , Hunter Bruce E. , Wang Geehuan , Meyer Edwin M.
Published: January 2005

The potential cytoprotective actions of a novel nicotinic agent 2,4‐dimethoxybenzilidene anabaseine (DMXB) were investigated in differentiated PC12 cells and transected rat septal cholinergic neurons in vivo. In NGF‐differentiated PC12 cells, removal of both NGF and serum led to cell loss, a reduced % of cells expressing neurites, the release of lactate dehydrogenase, and a decrease in total cellular protein. Cell loss was apparent within 24 h, and remained constant between 4–8 days post‐NGF removal. NGF alone (100 ng/ml), DMXB (10 μM), but not nicotine (10 μM), prevented these cell and neurite losses. DMXB‐induced cytoprotection was blocked by 1 μM mecamylamine. DMXB (1 mg/kg, ip) injected twice but not once per day protected cholinesterase‐staining septal neurons from retrograde degeneration following unilateral fimbrial transections. The twice per day DMXB injection‐protocol also decreased cell roundness among cholinesterase‐staining cells in the lesioned septal hemisphere compared to saline‐injected animals. These studies suggest that DMXB may exert cytoprotective activity in NGF‐sensitive neuronal populations. © 1994 Wiley‐Liss, Inc.
Effects of an extract ofGinkgo bilobaOn the action potential and associated transmembrane ionic currents in mammalian cardiac myocytes: Inhibition of isoproterenol‐induced chloride current
Authors: Masson Frédéric , Néliat Gervais , Drieu Katy , Defeudis Francis V. , Jean Thierry
Published: January 2005

Ventricular myocytes of guinea pig heart were used to examine the effects of an extract ofGinkgo biolba(EGb 761) on the action potential and individual transmembrane ionic currents. Elecrophysiological events were recorded using the “whole‐cell” configuration of the patch‐clamp technique. A systematic analysis of the data revealed that EGb 761 (5‐50 μg/ml) did not affect the normal action potential or the various ionic currents involved in its generation; i.e., fast inward sodium current (INa), inward calcium currents (ICaTand ICaL), delayed outward potassium current (IK), inward rectifying potassium current (IK1), and ATP‐senstive potassium current (IK‐ATP) evoked by 2,4‐dinitrophenol (2,4‐DNP). However, EGb 761 (≥5 μg/ml) elicited a pronouced concentration‐dependent and reversible inhibiton of isoproternol‐induced Cl−current (ICl), the maximal effect being observed at 50 μg/ml. This current may be significantly involved in sympathetic hyperactivity, hypoxia, and ischemia, pathophysiological conditions for which EGb 761 offers therapeutic benefit. The basic mechanism(s) underlying the inhibitory effect of EGb 761 on ICland the constituent(s) of EGb 761 responsible for this action remain to be identified, but it seems clear, from results which showed that neither ginkgolide B (50–500 ng/ml) nor biolobalide (150–1,500 ng/ml) influenced this current, that a terpenoid constituent of EGb 761 is probably not involved.
Advanced glycosylation endproducts: Role in diabetic and non‐diabetic vascular disease
Authors: Bucala Richard , Vlassara Helen , Cerami Anthony
Published: January 2005

Reducing sugars such as glucose react non‐enzymatically with the amino groups of macromolecules to initiate a chemical modification process known as advanced glycosylation. This pathway proceeds from reversible Schiff base adducts to a heterogenous group of irreversibly‐bound, cross‐linking moieties called advanced glycosylation endproducts or AGEs. Recent progress in our understanding of this process in vivo has affirmed the hypothesis that AGEs play an intimate role in the evolution of both diabetic and non‐diabetic vascular disease. Utilizing newly developed AGE‐specific ELISA techniques, AGEs have been identified to be present on a variety of vascular wall, lipoprotein, and lipid constituents. Protein‐bound AGEs, for example, contribute to a variety of pathological effects in vivo by acting to increase vascular permeability, enhance subintimal protein and lipoprotein deposition, and exert direct toxic effects on endothelial cells. Lipid‐AGEs promote oxidative modification and may contribute to atherogenesis by initiating the formation of oxidized low density lipoprotein (ox‐LDL). Aminoguanidine, a recently developed pharmacological inhibitor of advanced glycosylation, is presently undergoing phase II clinical trials and may offer a specific therapeutic modality for the treatment of pathological conditions that result from excessive advanced glycosylation.
Ecto‐enzymes and metabolism of extracellular ATP
Authors: Ziganshin Airat U. , Hoyle Charles H. V. , Burnstock Geoffrey
Published: January 2005

Extracellular ATP can produce various effects acting via P2‐purinoceptors. ATP is rapidly broken down by ecto‐ATPase and other ecto‐enzymes that limit its effect. Further, adenosine, a metabolite of ATP breakdown, can produce its own effect acting via P1‐purinoceptors, sometimes masking the effects of ATP. An inhibitor of ATP degradation would be a useful pharmacological tool to discriminate between effects of ATP and its metabolites, as well as to potentiate its actions. Diverse compounds that have been claimed to be inhibitors of ATP‐metabolising ectoenzymes are evaluated, but specific and selective Ca2+ /Mg2+ ‐dependent ecto‐ATPase inhibitors still appear to be lacking.
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

MK‐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

In 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

Indorenate 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

Filamentous 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

In 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

Voltage‐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

The 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

Adenosine 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

The 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

LY274600 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

DNA 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

Many 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

Dolasetron 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

In 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

The 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.
Antiinflammatory activity of topical auranofin in arachidonic acid‐ and phorbol ester‐induced inflammation in mice
Authors: Griswold Don E. , Chabot‐Fletcher Marie , Webb Edward F. , Martin Lenox , Hillegass Leonard
Published: January 2005

The antiarthritic, organogold compound auranofin was evaluated for its antiinflammatory activity in murine models of cutaneous inflammation. Initial studies involved the use of arachidonic acid‐induced inflammation, an evanescent response characterized by edema and neutrophil infiltration mediated, at least in part, by leukotrienes. The edema and myeloperoxidase (MPO) activity induced by application of arachidonic acid was assayed from the inflamed ears. After application of auranofin (1 mg or 1.47 m̈mol/ear in solution), inhibition of the MPO response was observed but little inhibition of the edematous response occurred. The application of 50 m̈l of 2% auranofin ointment (∼ 1.47 m̈mol/ear) administered after arachidonic acid resulted in the inhibition of both the edematous (54%) and the MPO (50%) components of the inflammatory response to arachidonic acid. It was found that auranofin in vitro weakly inhibited MPO activity, suggesting that inhibition of MPO‐derived oxidants might contribute to the antiinflammatory activity. In order to characterize further this antiinflammatory activity, the effect of auranofin on the response to the cutaneous application of phorbol ester (PMA) was studied. This psoriaform lesion involves intense infiltration of neurotrophils, microabcess formation and epidermal cell proliferation. The ear thickness and the MPO response were measured at 4 h after PMA application. In this model, auranofin in solution displayed marked, dose‐related antiinflammatory activity. The ED50s were calculated to be 0.12 (0.18 m̈mol) and 0.14 mg (0.21 m̈mol)/ear, respectively. An investigation of the antiinflammatory activity of the ointment was limited to the edematous response because of interference with the MPO analysis; however, potent antiinflammatory activity of the auranofin ointment proved to be dose‐related with an ED50 of 0.3% (0.22 m̈mol) at 2 h and 0.6% (0.44 m̈mol) at 4 h after PMA. In addition, if the response was allowed to proceed for 2 h before the application of ointment, further progression of the inflammation was essentially abolished. Despite strong inhibition of the inflammatory response, no significant alteration of PMA‐induced increased DNA content was demonstrable. Overall, the completeness of inhibition and potency observed with auranofin suggest that it may be of utility in the treatment of inflammatory diseases of the skin. ©1995 Wiley‐Liss, Inc.
Inhibition of pyruvate dehydrogenase kinase by halogenated acetophenones
Authors: Espinal Joseph , Leesnitzer Tony , Hassman Angela , Beggs Mark , Cobb Jeff
Published: January 2005

The activity of pyruvate dehydrogenase (PDH), and hence of glucose oxidation, is regulated by reversible phosphorylation. We have searched for novel PDH‐Kinase inhibitors using a high‐throughput microtiter plate assay. A series of halogenated acetophenones with potent activity against PDH‐Kinase (IC50 1–3 μM) and inactive towards other protein kinases was identified. The lead compound displayed non‐linear kinetics and was shown to be an uncompetitive inhibitor with respect to ATP. These novel inhibitors of PDH‐Kinase may be potential new drug leads for the treatment of diabetes or ischaemic conditions. © 1995 Wiley‐Liss, Inc.
Good laboratory practices and other regulatory issues: A European view
Authors: Sullivan Andrew T.
Published: January 2005

Safety pharmacology studies provide information on the effects of new chemical entities on physiological function in experimental animals and complement classical toxicology studies which assess effects on bodily structure. Data from these studies help to predict possible adverse effects of a compound that might be seen during administration to man, and should therefore be classified as safety studies. It is a regulatory requirement in most areas of the world that safety studies be carried out in compliance with the principles of Good Laboratory Practice. The way in which United Kingdom pharmaceutical companies approach safety pharmacology has been surveyed, and a comparison has been made with practices in the United States. © 1995 Wiley‐Liss, Inc.
Structure – activity relationships of nicotinic acetylcholine receptor agonists as potential treatments for dementia
Authors: Holladay Mark W. , Lebold Suzanne A. , Lin Nan‐Horng
Published: January 2005

The ability of nicotine to enhance cognition in animals and humans and to exert neuroprotective and anxiolytic‐like effects, as well as the negative correlation between smoking and Alzheimer's (and Parkinson's) disease, suggest a possible role for nicotinic agents in the treatment of some of the deficits that result from these conditions. Numerous compounds are known which activate neuronal nicotinic acetylcholine receptors (nAChRs) and which might serve as lead compounds toward the development of such agents. The diversity of nAChRs suggests the possibility of developing selective compounds which would have more favorable side‐effect profiles than the existing agents. An overview of the nicotinic system and model systems used to study nicotinic receptors is presented, followed by a discussion of structure–activity relationships of known lead compounds in assays that are thought to reflect therapeutic potential or possible side effects. © 1995 Wiley‐Liss, Inc.
History of combinatorial chemistry
Authors: Furka Árpád
Published: January 2005

The paper describes and compares the utility of the three chemical methods used for the synthesis of combinatorial libraries: (1) the mixed reactant method, (2) the portioningmixing method, and (3) light‐directed synthesis. It also deals with historical aspects of these methods and with the most important screening methods associated with them. © 1995 Wiley‐Liss, Inc.
Antinociceptive effects of the alkaloid epibatidine: Further studies on involvement of nicotinic receptors
Authors: Badio Barbara , Shi Dan , Martin H. Martin , Daly John W.
Published: January 2005

Epibatidine is a potent analgetic agent with high affinity for nicotinic receptors. The antinociceptive effects of epibatidine are blocked by both competitive and noncompetitive nicotinic antagonists. The L‐type calcium channel activator Bay K 8644 potentiates the antinociceptive effects of epibatidine, while nifedipine antagonizes the antinociceptive effects. Acute treatment with chlorisondamine leads to long‐term blockade of the antinociceptive effects of epibatidine. The antinociceptive effects of epibatidine are reduced in mice rendered tolerant to the behavioral effects of nicotine by chronic nicotine or caffeine treatment. Epibatidine has very high affinity for the major central nicotinic receptor to which [3H]nicotine binds. However, unlike nicotine and cytisine, epibatidine is very potent at ganglionic‐type nicotinic receptors. Epibatidine in cultured cells causes desensitization of both ganglionic and neuromuscular nicotinic receptors. Thus, like nicotine, chronic treatment with epibatidine might be expected to lead to tolerance. These studies establish epibatidine as a tool for the study of nicotinic pathways involved in pain perception. © 1995 Wiley‐Liss, Inc.
Procedure for the evaluation of the bioavailability of topical formulations in vivo as the rate and extent to which the active drug product is transferred from the vehicle to the skin
Authors: Vergés Josep , Castañeda‐Hernández Gilberto , Moragas José M.
Published: January 2005

A procedure was developed for the in vivo evaluation of the bioavailability of topical formulations containing a limited amount of the active drug product estimated as the rate and extent to which the drug is released from the vehicle to the skin. It is assumed that drug transfer follows Fick's law of diffusion. The formulation tested was a cream containing 40 μmol/ml (20 mg/ml) of sertaconazole, a novel imidazole antifungal agent, applied to healthy volunteers. Eight 9 cm2 squares were marked in the volar forearm surface and 0.1 ml of the cream was applied to each square by gentle rubbing with a plastic thimble. The actually applied dose was estimated considering the drug amount that adhered to the thimble. Then one area at a time was cleansed at 0, 1, 2, 4, 6, 8, 12, and 24 h and the amount of sertaconazole transferred to the skin was estimated by determination of the amount of drug removed by cleansing. Drug release from the vehicle to the skin increased with time, but then reached a plateau. The maximal amount of drug transferred to the skin was 85.5 ± 3.3% (mean ± S.D.) of the actually applied dose, and this value was considered an expression of the extent of drug release. The rate of release was estimated as the half‐life of the transfer process, which was 1.83 ± 0.76 h. This procedure is suitable for the evaluation of topical formulations containing a limited amount of the active drug product. © 1995 Wiley‐Liss, Inc.
Cyclic AMP and adenyl cyclase in the developing rat brain
Authors: Schmidt M. J. , Palmer E. C. , Dettbarn W.‐D. , Robison G. A.
Published: January 2005

The level of endogenous cyclic AMP in the rat brain in vivo began to increase markedly between the third and sixth days after birth, as did the ability of norepinephrine to stimulate the formation of cyclic AMP in brain tissue in vitro. Adenyl cyclase activity in broken cell preparations, when measure in the absence of sodium fluoride, increased with age up to a point, but began to decline between the fifth and ninth days postpartum. Activity continued to increase when measured in the presence of fluoride, suggesting that the apparent stimulatory effect of this ion may in fact be the reversal of an inhibitory influence which is absent or almost absent at birth. Cyclase activity at all ages was restricted to particulate matter, whereas apparent phosphodiesterase activity was present in particulate as well as soluble fractions. The catabolic system for cyclic AMP developed in a similar manner in both fractions. Theophylline produced the same degree of inhibition of this system at all ages.
Ontogenesis of sleep in human prematures after 32 weeks of conceptional age
Authors: Dreyfus‐Brisac C.
Published: January 2005

The ontogenesis of sleep was studied in prematures from 32 to 41 weeks of gestational age The characteristics of the EEG, the patterns and rate of respiration, the cardiac rate, body motility comprised of localized and diffuse movements, localized and diffuse jerks, clonic movements and electromyo‐graphic activity of the chin, as well as periods of total quietness were observed and correlated with the progressive organization of behavior in these infants. The data obtained at each gestational age, i.e., at 32–34 weeks, 35–37 weeks, and 38–41 weeks, were compared to those obtained in full‐term newborns. The relationships between the different events and the features of the EEG and of the respiratory patterns were ascertained and compared to similar data obtained in the full‐term newborn. This comparison shows that the premature at 40 weeks of gestational age has not attained a level of organization as high as that of the full‐term newborn. An hypothesis suggesting a possible mechanism of this discrepancy is presented.
Protein malnutrition induced during gestation: Its effect on pup development and maternal behavior
Authors: Massaro Thomas F. , Levitsky David A. , Barnes Richard H.
Published: January 2005

Repeated time‐lapse photographic observations were used to examine the ontogeny of behavioral development in prenatally malnourished rat pups following birth. Pups born to dams receiving a low protein diet (7% casein by weight) were fostered at birth to well‐nourished dams and behavioral observations were made at 4‐day intervals. Dams nursing gestationally malnourished pups were observed to spend more time in the nesting area with their pups towards the end of lactation. Moreover, the behavioral development (locomotion, feeding, and rearing and climbing activity) of gestationally malnourished offspring was depressed when compared to their controls. The results indicate that prenatal undernutrition alters the behavioral development of the offspring and maternal behavior of the dam in a manner which reduces the exposure of the pup to the immediate environment.
Effects of feeding on state and cardiac regulation in the infant
Authors: Harper R. M. , Hoppenbrouwers T. , Bannett D. , Hodgman J. , Sterman M. B. , McGinty D. J.
Published: January 2005

The effects of feeding on polygraphic state patterns and associated cardiac rates were examined in 8 normal infants using data collected during 12‐hr continuous monitoring sessions at 1 week and at 1, 2, 3, 4, and 6 months of age. The distribution of states and corresponding heart rate values were tabulated for each minute during 2‐hr periods preceding and following wakenings with and without feedings. Rapid eye movement (REM) sleep was significantly more prevalent immediately following a waking accompanied by feeding than waking alone. Moreover, a distinct relationship was demonstrated between feeding periods and the ongoing sleep cycle. In younger infants (1 week to 1 month), heart rates in quiet sleep (QS) and REM were higher after feeding than before, suggesting a general arousal influence. This was not the case with nonfeeding wakenings. In older infants (2–3 months), heart rates were higher after nonfeedings periods than before, but similar before and after feeding periods.
The development of sexual behavior in the rat: Role of preadult nutrition and environmental conditions
Authors: Hansen Stefan , Larsson Knut , Carlsson Sven G. , Sourander Patrick
Published: January 2005

Rats were subjected to pre‐ and postnatal undernutrition by restricting the food intake of their mothers (U); another group of rats was normally fed (N). Each nutrition group was divided into 3 subgroups by varying the degree of environmental stimulation: animals in the Max group were stimulated by handling and enriched rearing conditions; the Min group rats were subjected to social isolation; rats in the control condition (C) were raised under ordinary laboratory conditions. The onset of sexual activity was not affected in the U‐C male rats, but was delayed in both U‐Min and N‐Min rats. Although no difference existed in the age of puberty between the N‐Max and N‐C animals, the U‐Max rats displayed an advancement of puberty by 7 days in comparison to the U‐C rats. Undernutrition did not affect female sexual maturation; however the Max condition delayed this process in both nutrition groups.
Exploration, distraction, and habituation in rats reared in isolation
Authors: File Sandra E.
Published: January 2005

Rats reared in isolation have been reported to show increased motor activity; the purpose of the present experiment was to establish whether they also show enhanced exploratory and orienting responses. Rats were reared in isolation or in social groups from Day 20 to Day 45. Subgroups of each rearing condition were either left undisturbed, received daily handling, or received daily handling and were given objects in their cages. From Day 45 all the rats were rehoused in groups of 6, and testing began at Day 73. In a 1st test exploration was measured by the number of contacts with objects placed in the home cage; in a 2nd test exploration was measured by responses to a holeboard; and in a 3rd test orienting was measured by the distraction produced by the presentation of a tone. When tested in novel situations, in contrast to their enhanced motor activity, isolates showed reduced exploration and orienting. This may have been due to a discrepancy between their adaptation level (established during rearing) and their current level of sensory input. In all the tests the isolates showed normal habituation, both within sessions and between sessions. An inability to habituate is not, as has been claimed, a general characteristic of isolates.
Effects of amount of contact between mother and child on the mother's nursing behavior
Authors: Carlsson Sven G. , Fagerberg Helena , Horneman Göran , Hwang Carl‐Philip , Larsson Knut , Rödholm Margaretha , Schaller Joseph , Danielsson Bernt , Gundewall Christer
Published: January 2005

Short‐term effects of different amounts of body contact between mother and newborn on human nursing behavior were studied. Extended contact immediately after parturition was related to an increase in affective components of maternal nursing behavior observed on postpartum Days 2 and 4.
Neonatal ultrasounds elicited by odor cues
Authors: Conely Lynn , Bell Robert W.
Published: January 2005

Ultrasounds were monitored from neonatal rats following placement on 1 of 5 types of bedding material. Odors associated with the home cage or an adult male inhibited neonatal ultrasonic signaling. Odors associated with a novel lactating female elicited initially high rates of signaling, the rate lowering across the age range of pups tested. Odors associated with a novel virgin female or with an absence of animal odors elicited increasing rates of signaling across the age range tested.