bluuebunny/crossref_metadata_2025 huggingface dataset:
Do We “do”?
Authors: Sloman Steven A. , Lagnado David A.
Published: January 2005

A normative framework for modeling causal and counterfactual reasoning has been proposed by Spirtes, Glymour, and Scheines (1993; cf. Pearl, 2000). The framework takes as fundamental that reasoning from observation and intervention differ. Intervention includes actual manipulation as well as counterfactual manipulation of a model via thought. To represent intervention, Pearl employed the do operator that simplifies the structure of a causal model by disconnecting an intervened‐on variable from its normal causes. Construing the do operator as a psychological function affords predictions about how people reason when asked counterfactual questions about causal relations that we refer to as undoing, a family of effects that derive from the claim that intervened‐on variables become independent of their normal causes. Six studies support the prediction for causal (A causes B) arguments but not consistently for parallel conditional (if A then B) ones. Two of the studies show that effects are treated as diagnostic when their values are observed but nondiagnostic when they are intervened on. These results cannot be explained by theories that do not distinguish interventions from other sorts of events.
The Large‐Scale Structure of Semantic Networks: Statistical Analyses and a Model of Semantic Growth
Authors: Steyvers Mark , Tenenbaum Joshua B.
Published: January 2005

We present statistical analyses of the large‐scale structure of 3 types of semantic networks: word associations, WordNet, and Roget's Thesaurus. We show that they have a small‐world structure, characterized by sparse connectivity, short average path lengths between words, and strong local clustering. In addition, the distributions of the number of connections follow power laws that indicate a scale‐free pattern of connectivity, with most nodes having relatively few connections joined together through a small number of hubs with many connections. These regularities have also been found in certain other complex natural networks, such as the World Wide Web, but they are not consistent with many conventional models of semantic organization, based on inheritance hierarchies, arbitrarily structured networks, or high‐dimensional vector spaces. We propose that these structures reflect the mechanisms by which semantic networks grow. We describe a simple model for semantic growth, in which each new word or concept is connected to an existing network by differentiating the connectivity pattern of an existing node. This model generates appropriate small‐world statistics and power‐law connectivity distributions, and it also suggests one possible mechanistic basis for the effects of learning history variables (age of acquisition, usage frequency) on behavioral performance in semantic processing tasks.
Sketches from a Design Process: Creative Cognition Inferred From Intermediate Products
Authors: Jaarsveld Saskia , van Leeuwen Cees
Published: January 2005

Novice designers produced a sequence of sketches while inventing a logo for a novel brand of soft drink. The sketches were scored for the presence of specific objects, their local features and global composition. Self‐assessment scores for each sketch and art critics' scores for the end products were collected. It was investigated whether the design evolves in an essentially random fashion or according to an overall heuristic. The results indicated a macrostructure in the evolution of the design, characterized by two stages. For the majority of participants, the first stage is marked by the introduction and modification of novel objects and their local and global aspects; the second stage is characterized by changes in their global composition. The minority that showed the better designs has a different strategy, in which most global changes were made in the beginning. Although participants did not consciously apply these strategies, their self‐assessment scores reflect the stages of the process.
Perception as Abduction: Turning Sensor Data Into Meaningful Representation
Authors: Shanahan Murray
Published: January 2005

This article presents a formal theory of robot perception as a form of abduction. The theory pins down the process whereby low‐level sensor data is transformed into a symbolic representation of the external world, drawing together aspects such as incompleteness, top‐down information flow, active perception, attention, and sensor fusion in a unifying framework. In addition, a number of themes are identified that are common to both the engineer concerned with developing a rigorous theory of perception, such as the one on offer here, and the philosopher of mind who is exercised by questions relating to mental representation and intentionality.
Does the World Leak Into the Mind? Active Externalism, “Internalism” and Epistemology
Authors: Dartnall Terry
Published: January 2005

One of the arguments for active externalism (also known as the extended mind thesis) is that if a process counts as cognitive when it is performed in the head, it should also count as cognitive when it is performed in the world. Consequently, mind extends into the world. I argue for a corollary: We sometimes perform actions in our heads that we usually perform in the world, so that the world leaks into the mind. I call this internalism. Internalism has epistemological implications: If a process gives us an empirical discovery when it is performed in the world, it will also give us an empirical discovery when it is performed in the head. I look at a simple example that highlights this implication. I then explore the relation between internalism and active externalism in more detail and conclude by comparing internalism with mental modeling.
α1- and β1-Adrenoceptor Signaling Fully Compensates for β3-Adrenoceptor Deficiency in Brown Adipocyte Norepinephrine-Stimulated Glucose Uptake
Authors: Chernogubova Ekaterina , Hutchinson Dana S. , Nedergaard Jan , Bengtsson Tore
Published: January 2005

To assess the relative roles and potential contribution of adrenergic receptor subtypes other than the β3-adrenergic receptor in norepinephrine-mediated glucose uptake in brown adipocytes, we have here analyzed adrenergic activation of glucose uptake in primary cultures of brown adipocytes from wild-type and β3-adrenergic receptor knockout (KO) mice. In control cells in addition to high levels of β3-adrenergic receptor mRNA, there were relatively low α1A-, α1D-, and moderate β1-adrenergic receptor mRNA levels with no apparent expression of other adrenergic receptors. The levels of α1A-, α1D-, and β1-adrenergic receptor mRNA were not changed in the β3-KO brown adipocytes, indicating that the β3-adrenergic receptor ablation does not influence adrenergic gene expression in brown adipocytes in culture. As expected, the β3-adrenergic receptor agonists BRL-37344 and CL-316 243 did not induce 2-deoxy-d-glucose uptake in β3-KO brown adipocytes. Surprisingly, the endogenous adrenergic neurotransmitter norepinephrine induced the same concentration-dependent 2-deoxy-d-glucose uptake in wild-type and β3-KO brown adipocytes. This study demonstrates that β1-adrenergic receptors, and to a smaller degree α1-adrenergic receptors, functionally compensate for the lack of β3-adrenergic receptors in glucose uptake. β1-Adrenergic receptors activate glucose uptake through a cAMP/protein kinase A/phosphatidylinositol 3-kinase pathway, stimulating conventional and novel protein kinase Cs. The α1-adrenergic receptor component (that is not evident in wild-type cells) stimulates glucose uptake through a phosphatidylinositol 3-kinase and protein kinase C pathway in the β3-KO cells.
Drug-induced block of cardiac HERG potassium channels and development of torsade de pointes arrhythmias: the case of antipsychotics
Authors: Calderone Vincenzo , Testai Lara , Martinotti Enrica , Del Tacca Mario , Breschi Maria Cristina
Published: January 2005

The prolongation of the cardiac repolarization process, a result of the blocking of the Human Ether-a-go-go Related Gene potassium channel, is an undesired accessory property shared by many pharmacological classes of non-cardiovascular drugs. Often the delayed cardiac repolarization process can be identified by a prolongation of the QT interval of the electrocardiograph. In these conditions, premature action potentials can trigger a dangerous polymorphic ventricular tachyarrhythmia, known as torsade de pointes, which occasionally can result in lethal ventricular fibrillation. In this work, brief descriptions of the electrophysiological basis of torsade de pointes and of the several pharmacological classes of torsadogenic drugs are given. Attention is focused on antipsychotics, with a deeper overview on the experimental and clinical reports about their torsadogenic properties.
Effects of glucose, fructose and 5-hydroxymethyl-2-furaldehyde on the presystemic metabolism and absorption of glycyrrhizin in rabbits
Authors: Hou Y C , Ching H , Chao P D L , Tsai S Y , Wen K C , Hsieh P H , Hsiu S L
Published: January 2005

Our previous study reported that co-administration of honey significantly increased the serum levels of glycyrrhetic acid (GA) after oral administration of glycyrrhizin (GZ) in rabbits. The components of honey are sucrose, glucose, fructose and 5-hydroxymethyl-furaldehyde (HMF). To clarify the causative component(s) in honey that altered the metabolic pharmacokinetics of GZ, rabbits were given GZ (150 mg kg−1) with and without glucose (5g/rabbit), fructose (5 g/rabbit) and HMF (1 mg kg−1), respectively, in crossover designs. An HPLC method was used to determine concentrations of GZ and GA in serum as well as GA and 3-dehydroglycyrrhetic acid (3-dehydroGA) in faeces suspension. A noncompartment model was used to calculate the pharmacokinetic parameters and analysis of variance was used for statistical comparison. Our results indicated that the area under curve (AUC) of GA was significantly increased by 29% when HMF was coadministered, whereas the pharmacokinetics of GZ and GA were not significantly altered by coadministration of glucose or fructose. An in-vitro study, using faeces to incubate GZ and GA individually, indicated that HMF significantly inhibited the oxidation of GA to 3-dehydroGA and this may explain the enhanced GA absorption in-vivo. It was concluded that HMF is the causative component in honey that affects the presystemic metabolism and pharmacokinetics of GZ in-vivo.
Fadolmidine-induced ocular hypotension in normotensive rabbits
Authors: Savolainen Jouko , Niemi Riku , Mäntylä Antti , Huuskonen Juhani , Järvinen Tomi
Published: January 2005

Fadolmidine, a novel selective α-adrenoceptor agonist, was evaluated for its efficacy to lower intraocular pressure in normotensive rabbits (n = 5–6). The dose-response profile between 0.004 μg and 12.5 μg of fadolmidine was determined. The effect of pH on the partition of fadolmidine was studied in order to select an optimal pH for topical fadolmidine administration. After topical administration, fadolmidine significantly lowered the intraocular pressure in normotensive rabbits. The onset of action was immediate, with no initial increase in intraocular pressure. A significant decrease in intraocular pressure was already observed at 1 h after dosing. The maximum decrease in intraocular pressure was observed after a 2.5 μg dose of fadolmidine in both eyes at 2 h after dosing. The mean maximum decrease in the treated and untreated eye was 6.4 mmHg and 3.9 mmHg, respectively. In conclusion, fadolmidine is a potent intraocular pressure lowering agent. In addition, fadolmidine does not cause a significant initial increase in intraocular pressure. Because of the strong dependence of the distribution coefficient on pH, the pH of the administered solution is important, with physiological pH being optimal in this respect.
Polyphenols from plants used in traditional Indonesian medicine (Jamu): uptake and antioxidative effects in rat H4IIE hepatoma cells
Authors: Steffan Bärbel , Wätjen Wim , Michels Gudrun , Niering Petra , Wray Victor , Ebel Rainer , Edrada RuAngelie , Kahl Regine , Proksch Peter
Published: January 2005

Phytochemical investigation of plants used in traditional Indonesian medicine (Jamu) yielded lignans (pinoresinol, 9α-hydroxypinoresinol and salicifoliol), flavonoids (3-β-D-glucopyranosyl-(1→6)-β-d-glucopyranosylkaempferol, luteolin and apigenin) and coumarins (coumarin, 8-hydroxycoumarin and 5-hydroxycoumarin). The beneficial effects of the respective plants for human health are thought to be associated with antioxidative activity. In the present study, the antioxidative capacity of the isolated compounds was determined in an in-vitro assay. Luteolin and kaempferol (cleavage product of 3-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosylkaempferol, which is thought to be formed in the intestine) showed strong antioxidant activity; pinoresinol and 9α-hydroxypinoresinol showed only minor antioxidative effects. The coumarins, as well as apigenin and 3-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosylkaempferol were inactive. The antioxidative effects of luteolin, kaempferol and pinoresinol were further investigated in H4IIE rat hepatoma cells. A strong protective effect of kaempferol and luteolin was found against H2O2-mediated intracellular reactive oxygen species formation measured using the dichlorofluorescein assay and H2O2-mediated DNA strand breaks. Pinoresinol did not have a protective effect against H2O2-mediated DNA-damage, but in the dichlorofluorescein assay, an antioxidative effect was detectable. During studies with H4IIE cells, kaempferol, luteolin and pinoresinol were taken up by the cells within 60 min. The flavonoids were found to be relatively toxic at higher concentrations, while pinoresinol was less cytotoxic. In conclusion, kaempferol and luteolin, at low concentrations (≤ 50μm), protect H4IIE cells against oxidative stress but are cytotoxic at higher concentrations; the biological effects of pinoresinol are less prominent in comparison. These results are important for the identification of pharmacologically active substances from traditional Indonesian medicinal plants.
The changes in the endothelial expression of cell adhesion molecules and iNOS in the vessel wall after the short-term administration of simvastatin in rabbit model of atherosclerosis
Authors: Nachtigal Petr , Kopecky Martin , Solichova Dagmar , Zdansky Petr , Semecky Vladimir
Published: January 2005

Cell adhesion molecules P-selectin, VCAM-1 and ICAM-1 play an important role in the pathogenesis of atherosclerosis. High levels of nitric oxide (NO) produced by inducible NO synthase (iNOS) have been associated with atherosclerotic processes. Simvastatin is an HMG-CoA reductase inhibitor responsible for many clinical benefits. The aim of this study was to detect and quantify changes in endothelial expression of P-selectin, VCAM-1, ICAM-1 and iNOS in the vessel wall after the short-term administration of simvastatin in a rabbit model of atherosclerosis. Eighteen New Zealand White rabbits were randomly divided into three groups (n = 6). In the cholesterol group, rabbits consumed an atherogenic diet (0.4% cholesterol) for eight weeks. In the simvastatin group, rabbits consumed an atherogenic diet for six weeks and then consumed an atherogenic diet supplemented with simvastatin (10 mg kg−1) for two weeks. Biochemical analysis showed that administration of simvastatin led to an almost two-fold lowering of the total serum cholesterol, VLDL, LDL and HDL, but not triglycerides, compared with the cholesterol-fed rabbits only. Stereological analysis of the immuno-histochemical staining revealed that administration of simvastatin (10 mg kg−1 daily) in an atherogenic diet decreased the endothelial expression of P-selectin, ICAM-1 and iNOS in both aortic arch and carotid artery compared with the cholesterol fed-rabbits only. We conclude that simvastatin has beneficial effects on endothelial function by decreasing expression of P-selectin, ICAM-1 and iNOS in endothelial cells in the very early stages of atherogenesis.
In-vitro evaluation of khaya and albizia gums as compression coatings for drug targeting to the colon
Authors: Odeku Oluwatoyin A , Fell John T
Published: January 2005

Khaya and albizia gums were evaluated as compression coatings for target drug delivery to the colon using indometacin (a water insoluble drug) and paracetamol (a water soluble drug) as model drugs. The core tablets were compression-coated with 300 and 400mg of 100% khaya gum, 100% albizia gum and a mixture of khaya and albizia gum (1:1). Drug release studies were carried out in 0.1M HCI (pH 1.2) for 2h, Sorensen's buffer (pH 7.4) for 3 h and then in phosphate-buffered saline (pH 6.8) or in simulated colonic fluid for the rest of the experiment to mimic the physiological conditions from the mouth to colon. The results indicated that khaya and albizia gums were capable of protecting the core tablet in the physiological environment of the stomach and small intestine, with albizia gum showing greater ability than khaya gum. The release from tablets coated with the mixture of khaya and albizia gums was midway between the two individual gums, indicating that there was no interaction between the gums. Studies carried out using rat caecal matter in phosphate-buffered saline at pH 6.8 (simulated colonic fluid) showed that the gums were susceptible to degradation by the colonic bacterial enzymes, leading to release of the drug. The results demonstrate that khaya gum and albizia gum have potential for drug targeting to the colon.
Synthesis of baicalein derivatives as potential anti-aggregatory and anti-inflammatory agents
Authors: Huang Wen-Hsin , Lee An-Rong , Chien Pei-Yu , Chou Tz-Chong
Published: January 2005

The direct acylation of trimethoxyphenol (1) with substituted cinnamoyl chlorides followed by Fries rearrangement and cyclization afforded a practical route for the synthesis of novel baicalein derivatives 4 functionalized on the B-ring in good overall yields. In the methylthiazoletetrazolium bromide (MTT) assay, none of the synthetic polyhydroxyflavonoids were cytotoxic at concentrations up to 200 μm on lipopolysaccharide (LPS)-activated murine RAW 264.7 macrophages over 24 h, while in the same cells they significantly inhibited NO production. Among the derivatives, 4d (IC50 = 46.1 ± 0.3 μm) was found to exhibit the most potent activity compared with N-nitro-L-arginine methyl ester (L-NAME, IC50 > 300 μm). Compounds 4b, 4e, 4f, 4h and 4i remarkably inhibited platelet aggregation induced by arachidonic acid and collagen in rabbit washed platelets compared with aspirin. Analysis of their structure-activity relationships indicated that, in the structural modification on the B-ring of baicalein (4a), introduction of appropriate electro-withdrawing substituents such as 2-CI (4b), 4-CI (4d), and 4-phenyl (4i) notably increased the potency on the inhibition of LPS-activated NO production and arachidonic acid- and collagen-induced aggregation. Baicalein itself was equally effective in the inhibition of LPS-activated NO production and collagen-induced aggregation but less active against arachidonic acid-induced aggregation. Our in-vitro results suggested that by appropriate structural modification of baicalein it may be possible to develop novel therapeutic agents against platelet-aggregation and inflammation.
Pharmacokinetic advantage of intraperitoneal injection of docetaxel in the treatment for peritoneal dissemination of cancer in mice
Authors: Shimada Tsutomu , Nomura Masaaki , Yokogawa Koichi , Endo Yoshio , Sasaki Takuma , Miyamoto Ken-ichi , Yonemura Yutaka
Published: January 2005

Intraperitoneal administration of docetaxel has been used to treat peritoneal dissemination of cancer, but its safety has not yet been confirmed. We have compared the pharmacokinetic behaviour of docetaxel after intravenous and intraperitoneal administration in CD-1-nu/nu mice bearing MKN-45P, a gastric cancer variant line producing peritoneal dissemination. Docetaxel (8mg kg−1) was intravenously or intraperitoneally injected into the mice and at designated times the drug concentration was measured in plasma, ascites fluid, and abdominal tissues (liver, kidney, intestine and spleen, solid cancer, and suspended free cancer). The pharmacokinetic behaviour of docetaxel was similar in control mice and cancer-bearing mice after administration via either route, except that the transfer of docetaxel from the abdominal cavity to systemic blood (plasma) was slower in cancer-bearing mice than in control mice. As expected, the intraperitoneal drug concentration was much higher (approximately 100-fold) and was maintained for a longer time in the intraperitoneal injection group than in the intravenous injection group. The drug concentrations in peritoneal solid cancer tissue and suspended free cancer cells were also significantly higher for a longer time in the intraperitoneal injection group than in the intravenous injection group. The values of the plasma area under concentration-time curves (AUC) were similar for both administration routes. The ratio of AUC ascite/AUC plasma after intraperitoneal administration was higher than after intravenous administration. The drug concentration in abdominal organs after intraperitoneal injection was lower during the first 2 h, then became similar to those after intravenous injection. These results indicated that the intraperitoneal administration of docetaxel for peritoneal dissemination was likely to be an effective treatment method, without causing any increase in systemic toxicity.
The anxiolytic-like effect of 5-HT1B receptor ligands in rats: a possible mechanism of action
Authors: Chojnacka-Wójcik Ewa , Kłodzińska Aleksandra , Tatarczyńska Ewa
Published: January 2005

We have examined the effect of lesions of 5-hydroxytryptamine (5-HT) neurons, produced by p-chloroamphetamine (p-CA; 2 times 10 mg kg−1), and the influence of flumazenil (Ro 15–1788, 10 mg kg−1), a benzodiazepine receptor antagonist, on the anxiolytic-like activity of CP 94253 (5-propoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1-H-pyrrolo[3,2-b]pyridine), a 5-HT1B receptor agonist, SB 216641 (N-[3-[3-(dimethylamino)ethoxy]-4-methoxyphenyl]-2′-methyl-4′-(5-methyl-1,2,4-oxadiazol-3-yl)-[1,1′-biphenyl]-4-carboxamide), a 5-HT1B receptor antagonist, and GR 127935 (N-[4-methoxy-3-(4-methyl-l-piperazinyl)phenyl]-2′-methyl-4′-(5-methyl-1,2,4-oxadiazol-3-yl)-1, 1′-biphenyl-4-carboxamide), a 5-HT1B/1D receptor antagonist, in the Vogel conflict drinking test in rats. Diazepam was used as a reference compound. CP 94253 (2.5 mg kg−1), SB 216641 (2.5 mg kg−1), GR 127935 (10 mg kg−1) and diazepam (5 mg kg−1) significantly increased the number of shocks accepted during experimental sessions in the conflict drinking test in vehicle- and p-CA-pretreated rats. Flumazenil did not change the anxiolytic-like effect of CP 94253 (2.5 mg kg−1), but wholly blocked the anxiolytic-like effects of SB 216641 (2.5 mg kg−1), GR 127935 (10 mg kg−1) and diazepam (5 mg kg−1). p-CA and flumazenil alone were inactive in the conflict drinking test. The results suggested that the anxiolytic-like effect of the 5-HT1B receptor ligands CP 94253, SB 216641 and GR 127935 was possibly linked to the postsynaptic 5-HT1B receptors or/and 5-HT1B heteroreceptors. The results suggested also that benzodiazepine receptors were indirectly involved in the effects of SB 216641 and GR 127935 (but not of CP 94253), which might have been due to a possible interaction between the 5-HT and the GABA/benzodiazepine systems.
Oleanolic acid nanosuspensions: preparation, in-vitro characterization and enhanced hepatoprotective effect
Authors: Chen Yajun , Liu Jie , Yang Xiangliang , Zhao Xiaoling , Xu Huibi
Published: January 2005

Oleanolic acid is a naturally derived triterpene used clinically in the treatment of hepatitis in China, but its poor solubility often leads to poor bioavailability. In the present study, oleanolic acid nanosuspensions were prepared by the nanoprecipitation method and then systematically characterized. The average particle size of the obtained nanosuspensions was 284.9 nm, with a polydispersity index of 0.216. Transmission electron microscopy and atomic force microscopy showed that the drug existed as spherical or near-spherical nanoparticles in the nanosuspensions. Differential scanning calorimetry and X-ray diffraction studies indicated that oleanolic acid was present in an amorphous state in the lyophilized nanosuspensions. At 25°C, the saturation solubility of oleanolic acid was increased by about 6 times after nanoation (25.72 μg mL−1 vs 4.37 μg mL−1). In the in-vitro drug release experiments, the lyophilized nanosuspensions showed a faster drug dissolution rate than that of the coarse drug powder (approx. 90% vs 15% during the first 20 min), and nearly 95% of the oleanolic acid was released by 120 min. As evidenced by the lower serum alanine aminotransferase activity and liver malondiadehyde content, pre-treatment with oleanolic acid nanosuspensions significantly enhanced the hepatoprotective effect of oleanolic acid against carbon tetrachlorideinduced liver injury.
Modulatory effects of Aloe vera leaf gel extract on oxidative stress in rats treated with streptozotocin
Authors: Rajasekaran S , Sivagnanam K , Subramanian S
Published: January 2005

Oxidative stress is currently suggested as a mechanism underlying diabetes and diabetic-related complications. Oxidative stress results from an imbalance between radical-generating and radical-scavenging systems. Many secondary plant metabolites have been reported to possess antioxidant activity. This study was designed to evaluate the potential antioxidative activity of the ethanolic extract from Aloe vera leaf gel in the plasma and pancreas of streptozotocin (STZ)-induced diabetic rats. Glibenclamide was used as a standard reference drug. Oral administration of ethanolic extract at a concentration of 300 mg kg−1 body weight for 21 days resulted in a significant reduction in fasting blood glucose, thiobarbituric acid reactive substances, hydroperoxides and alpha-tocopherol and significant improvement in ascorbic acid, reduced glutathione and insulin in the plasma of diabetic rats. Similarly, the treatment also resulted in a significant reduction in thiobarbituric acid reactive substances, hydroperoxides, superoxide dismutase, catalase and glutathione peroxidase and significant improvement in reduced glutathione in the pancreas of STZ-induced diabetic rats when compared with untreated diabetic rats. The ethanolic extract appeared to be more effective than glibenclamide in controlling oxidative stress. Thus, this study confirms the ethnopharmacological use of Aloe vera in ameliorating the oxidative stress found in diabetes.
In-vivo effects of the 1,2,4-piperazine derivatives MM5 and MC1, putative 5-HT agonists, on dopamine and serotonin release in rat prefrontal cortex
Authors: Iskra-Jopa Joanna , Golembiowska Krystyna , Dziubina Anna , Cybulski Marcin , Duszynńska Beata , Chilmonczyk Zdzislaw
Published: January 2005

Two 1,2,4-substituted derivatives of piperazine were tested for their effect on dopamine and serotonin (5-HT) release in rat prefrontal cortex. Both compounds, 1-[4-(4-chinolin-2-yl-piperazin-1-yl)-butyl]piperidin-2-on (MM5) and 1-[4-(2-methyl-4-chinolin-2-yl-piperazin-1-yl)-butyl]-8-azaspiro [4.5]decano-7,9-dion (MC1), produced hypothermia in mice and showed affinity for 5-HT1A receptors in-vitro. Like the selective 5-HT1A agonist 8-OH-DPAT (0.1 mg kg−1), MM5 given peripherally (30 mg kg−1) decreased the extracellular 5-HT level in rat prefrontal cortex, while MC1 suppressed 5-HT release at a higher dose (40 mg kg−1), but not at a lower one (30 mg kg−1). The effect of both compounds on 5-HT release was abolished by WAY 100635 (0.3 mg kg−1). MC1 (30 and 40 mg kg−1), but not MM5, raised cortical dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and extracellular homovanillic acid (HVA) levels. The effect of MC1 on dopamine release was reversed by neither WAY 100635 nor the non-selective 5-HT2 antagonist ritanserin (2 mg kg−1). However, ritanserin prevented the effect of the higher dose of MC1 on 5-HT release. The results of this study suggest that MM5 exhibits the profile of a 5-HT1A agonist devoid of dopaminergic activity. MC1 seems to possess moderate agonist activity at 5-HT1A and 5-HT2A receptors, while acting on 5-HT release in the rat prefrontal cortex. However, the facilitation of dopamine release by this compound does not seem to be related to its affinity for 5-HT1A and 5-HT2A receptors.
The metallopeptide antibiotic bacitracin inhibits interleukin-12 αβ and β2 secretion
Authors: Alloza I , Vandenbroeck K
Published: January 2005

The metalloantibiotic bacitracin is a known inhibitor of protein disulfide isomerase (PDI). The disulfide-linked interleukin-12 (IL-12) αβ-heterodimer and β2-homodimer forms are crucial mediators of cell-mediated immune responses and inflammatory reactions. Bacitracin was found to potently block secretion of both the αβ- and β2-dimer forms of IL-12, while it did not affect secretion of the β-monomer. This inhibition coincided with a reduction in the intracellular amount of PDI found in complex with the β-chain during intracellular transit. Bacitracin did not affect mRNA levels of the α- and β-chain. Similar to bacitracin, N-acetylcysteine blocked αβ- and β2-secretion as well as PDI-β-chain complex formation. Thus, blocking PDI or shifting the endoplasmic reticulum towards a more reduced status disrupts the oxidative folding pathway or assembly of IL-12 dimer forms. The assembly stage of cytokines in the endoplasmic reticulum may represent a novel target for pharmacological intervention.
A pharmacokinetic/pharmacodynamic model for a platelet activating factor antagonist based on data arising from Phase I studies
Authors: Evans Lynne , Aarons Leon , Brearley Chris
Published: January 2005

A nonlinear mixed-effects modelling approach was used to analyse pharmacokinetic and pharma-codynamic data from two Phase I studies of a platelet activating factor (PAF) antagonist under development for the treatment of seasonal allergic rhinitis. Data for single-dose (8 subjects) and multiple-dose (9 subjects) administration were available for analysis with a program based on an EM algorithm. Pharmacokinetic analyses of plasma drug concentrations were performed using a biexponential model with first-order absorption. PAF response data were modelled with a hyperbolic Emax model. The drug showed nonlinear pharmacokinetics, with the clearance decreasing from 46.0 to 27.1 L h−1 over a dose range of 160–480 mg. There was an apparent dose dependency within the C50 (concentration producing 50% of the maximum effect) but at higher doses most of the data was above the estimated C50 and when the data was analysed simultaneously a value of 17.57 ng mL−1 was obtained for C50, with considerable intersubject variability (103%). Consistent results were obtained from the two studies and the population and individual pharmacodynamic parameter estimates from the analyses provided predicted responses that were in good agreement with the observed data. The results were used to simulate a 320-mg twice-daily dosing regimen.
Gastroprotective activity of a new semi-synthetic solidagenone derivative in mice
Authors: Rodríguez Jaime A , Theoduloz Cristina , Sánchez Marianela , Yáñez Tania , Razmilic Iván , Schmeda-Hirschmann Guillermo
Published: January 2005

The gastroprotective activity of the new semi-synthetic solidagenone derivative 15,16-epoxy-8(9),13(16),14-labdatrien-7β-methoxy-6β-ol (ELMO) has been assessed on the model of HCl/EtOH-induced gastric lesions in mice. Human gastric epithelial cells (AGS) and fibroblasts (MRC-5) were used to determine its mode of action. The effect of ELMO on the prostaglandin E2 content, cellular reduced glutathione (GSH) and protection against damage induced by sodium taurocholate was assessed against AGS cells. The effect of ELMO on the growth of AGS and fibroblast cultures was evaluated. The superoxide anion scavenging capacity of the compound was studied also. The cytotoxicity of ELMO, expressed as cell viability, was assessed using two independent endpoints: neutral red uptake (NRU) and the reduction of 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) for MRC-5 fibroblasts and NRU for AGS cells. A single oral dose of ELMO (10 and 20 mg kg−1) inhibited the appearance of gastric lesions in mice displaying similar values to lansoprazole at 20 mg kg−1. At 40 μm ELMO increased the prostaglandin E2 content but not GSH in AGS cells. The compound showed no effect on sodium taurocholate-induced damage and was devoid of superoxide anion scavenging activity. Concentrations of 0.5, 1, 2 and 4 μm stimulated fibroblast but not AGS cell proliferation. The compound showed weak cytotoxicity with values (IC50) of 411 (NRU) and 418 μm (MTT) for fibroblasts and 261 μm (NRU) for AGS cells. The results support further pharmacological study of this compound as a potential new anti-ulcerogenic drug.
Alteration of the pharmacokinetics of theophylline by rutaecarpine, an alkaloid of the medicinal herb Evodia rutaecarpa, in rats
Authors: Ueng Yune-Fang , Tsai Tung-Hu , Don Ming-Jaw , Chen Ruei-Ming , Chen Ta-Liang
Published: January 2005

Rutaecarpine is a main active alkaloid present in the medicinal herb, Evodia rutaecarpa. The cyto-chrome P450 (CYP) 1A2 substrate, theophylline, is an important therapeutic agent for the treatment of asthma, but has a narrow therapeutic index. To evaluate the pharmacokinetic interaction of theophyl-line with rutaecarpine, the effects of rutaecarpine on CYP1A2 activity and theophylline pharmaco-kinetics were investigated. Oral treatment of Sprague-Dawley rats with 50 mg kg−1 rutaecarpine for three days through a gastrogavage caused a 4- and 3-fold increase in liver microsomal 7-ethoxyresorufin O-deethylation (EROD) and 7-methoxyresorufin O-demethylation activity, respectively. In the kidney, rutaecarpine treatment caused a 3-fold increase in EROD activity. In the lungs, EROD activity was elevated from an undetectable to a detectable level by rutaecarpine. Pharmacokinetic parameters of theophylline were determined using a microdialysis sampling method. Rutaecarpine pre-treatment increased the clearance of theophylline in a dose-dependent manner. Pre-treatment of rats with 50 mg kg−1 rutaecarpine caused a 3-fold increase in theophylline clearance and a 70%, 68% and 68% decrease in the area under the concentration-time curve (AUC), mean residence time (MRT) and half-life, respectively. These results demonstrated that rutaecarpine treatment elevated CYP1A2 catalytic activity and theophylline excretion in rats. In patients taking theophylline, adverse effects might be noticed when a rutaecarpine-containing herbal preparation is used concomitantly.
Rats are able to navigate in virtual environments
Authors: Hölscher C. , Schnee A. , Dahmen H. , Setia L. , Mallot H. A.
Published: January 2005

Virtual reality (VR) systems are useful tools that enable users to alter environmental settings and the location of landmarks in an accurate and fast way. Primates have been shown to be able to navigate in virtual environments. For rodents, however, all previous attempts to develop VR systems in which rats behave in the same way as in corresponding 3-D environments have failed. The question arises as to whether, in principle, rodents can be trained to navigate in a properly designed virtual environment (VE), or whether this peculiarity is limited to primates and humans. We built a virtual reality set-up that takes the wide-angle visual system of rats into account. We show for the first time that rats learn spatial tasks in this VE quite readily. This set-up opens up new opportunities for investigations of information processing in navigation (e.g. the importance of optic flow or vestibular input).
A distinct carbonic anhydrase in the mucus of the colon of humans and other mammals
Authors: Kleinke Tanja , Wagner Siegfried , John Harald , Hewett-Emmett David , Parkkila Seppo , Forssmann Wolf-Georg , Gros Gerolf
Published: January 2005

We have collected gastrointestinal, mainly colonic, mucus from humans,guinea pigs, rats, and normal and carbonic anhydrase II (CAII)-deficient mice. In the mucus of all species, substantial CA activity was present. Using antibodies against human CA isoforms we found that the human mucus CA differs from cytosolic CAI and CAII, membrane-bound CAIV, and the secreted CAVI of saliva. The high sensitivity of mucus CA to acetazolamide rules out its identity with cytosolic CAIII. Partial sequences obtained from the purified human mucus CA show similarity, but not identity, with human CAI, and clear differences from the other known CAs. Additional evidence concerning the CA isoform present in mucus was obtained for the mucus CA of other species and was derived from: (1) the mucus of CAII-deficient mice, whose high CA activity confirms that it is not CAII that is responsible; (2) the inhibitory effect of iodide, which shows that mucus CA from mice, guinea pig and humans does not have the high anion sensitivity of CAI; (3) the inactivating effect of 0.2%SDS on guinea pig, mouse and human mucus CA, ruling out the SDS-resistant CAIV; and (4) the partitioning of guinea-pig mucus CA into the water phase in Triton X114 phase separation experiments, which also argues against its identity with membrane-bound CAs, such as CAIV. A comparison of colonic mucus CA activity in normal and germ-free rats indicates that the mucus CA is not of bacterial origin but is produced by the gastrointestinal tissues. We conclude(from its immunoreactivity, from iodide inhibition and from partial amino acid sequences) that mucus CA of human origin probably represents an isozyme, which is specific for mucus and is not identical with the known CA isozymes. The results obtained for mucus CA of other species collectively point in the same direction.
Dynamic flight stability of a hovering bumblebee
Authors: Sun Mao , Xiong Yan
Published: January 2005

The longitudinal dynamic flight stability of a hovering bumblebee was studied using the method of computational fluid dynamics to compute the aerodynamic derivatives and the techniques of eigenvalue and eigenvector analysis for solving the equations of motion.

For the longitudinal disturbed motion, three natural modes were identified:one unstable oscillatory mode, one stable fast subsidence mode and one stable slow subsidence mode. The unstable oscillatory mode consists of pitching and horizontal moving oscillations with negligible vertical motion. The period of the oscillations is 0.32 s (approx. 50 times the wingbeat period of the bumblebee). The oscillations double in amplitude in 0.1 s; coupling of nose-up pitching with forward horizontal motion (and nose-down pitching with backward horizontal motion) in this mode causes the instability. The stable fast subsidence mode consists of monotonic pitching and horizontal motions, which decay to half of the starting values in 0.024 s. The stable slow subsidence mode is mainly a monotonic descending (or ascending) motion, which decays to half of its starting value in 0.37 s.

Due to the unstable oscillatory mode, the hovering flight of the bumblebee is dynamically unstable. However, the instability might not be a great problem to a bumblebee that tries to stay hovering: the time for the initial disturbances to double (0.1 s) is more than 15 times the wingbeat period (6.4 ms), and the bumblebee has plenty of time to adjust its wing motion before the disturbances grow large.
Cell volume control inParamecium: factors that activate the control mechanisms
Authors: Iwamoto Masaaki , Sugino Kazuyuki , Allen Richard D. , Naitoh Yutaka
Published: January 2005

A fresh water protozoan Paramecium multimicronucleatum adapted to a given solution was found to swell until the osmotic pressure difference between the cytosol and the solution balanced the cytosolic pressure. The cytosolic pressure was generated as the cell swelled osmotically. When either one or both of these pressures was somehow modified, cell volume would change until a new balance between these pressures was established. A hypothetical osmolyte transport mechanism(s) was presumably activated when the cytosolic pressure exceeded the threshold value of ∼1.5 × 105 Pa as the cell swelled after its subjection to a decreased osmolarity. The cytosolic osmolarity thereby decreased and the volume of the swollen cell resumed its initial value. This corresponds to regulatory volume decrease (RVD). By contrast, another hypothetical osmolyte transport mechanism(s) was activated when the cell shrank after its subjection to an increased osmolarity. The cytosolic osmolarity thereby increased and volume of the shrunken cell resumed its initial value. This corresponds to regulatory volume increase (RVI). The osmolyte transport mechanism responsible for RVD might be activated again when the external osmolarity decreases further, and the cytosolic osmolarity thereby decreases to the next lower level. Similarly, another osmolyte transport mechanism responsible for RVI might be activated again when the external osmolarity increases further, and the cytosolic osmolarity thereby increases to the next higher level. Stepwise changes in the cytosolic osmolarity caused by a gradual change in the adaptation osmolarity found in P. multimicronucleatum is attributable to these osmolyte transport mechanisms. An abrupt change in the amount of fluid discharged from the contractile vacuole seen immediately after changing the external osmolarity reduces an abrupt change in cell volume and thereby protects the cell from the disruption of the plasma membrane by excessive stretch or dehydration during shrinkage.
Pigmentation in the sensory organs of the ascidian larva is essential for normal behavior
Authors: Jiang Di , Tresser Jason W. , Horie Takeo , Tsuda Motoyuki , Smith William C.
Published: January 2005

Free-living animals and their larvae utilize light and gravity as cues to navigate in open space. Detection and response to these environmental stimuli are important for the dispersal and settlement of ascidian larvae. Two pigmented structures in the brain of the ascidian larva, the ocellus and the otolith, have been shown to function as the photoreceptive and gravity sensitive organs, respectively. Here, we show that pigmentation is essential for proper phototactic and geotactic behavior in larvae of the ascidian species Ciona savignyi. Two recessive and complementing mutant lines of C. savignyi, immaculate and spotless, that specifically disrupt the pigmentation of the sensory organs during larval development are described. Homozygous mutant larvae are unable to respond properly to gravity and illumination cues while settling. Genetic analysis shows that spotless is caused by a point mutation within the tyrosinase gene that creates a premature stop codon, while the molecular nature of immaculate is unknown. Although the role of pigmentation in the ocellus of C. savignyi is similar to that in vertebrate visual systems, our results demonstrate a novel use of melanin in geotactic behavior.
Circadian rhythms of behavioral cone sensitivity and long wavelength opsin mRNA expression: a correlation study in zebrafish
Authors: Li Ping , Temple Shelby , Gao Yan , Haimberger Theordore J. , Hawryshyn Craig W. , Li Lei
Published: January 2005

Using a behavioral assay based on visually mediated escape responses, we measured long-wavelength-sensitive red cone (LC) sensitivities in zebrafish. In a 24 h period, the zebrafish were least sensitive to red light in the early morning and most sensitive in the late afternoon. To investigate if the fluctuation of behavioral cone sensitivity correlates with opsin gene expression, we measured LC opsin mRNA expression at different times in the day and night under different lighting conditions. Under a normal light–dark cycle, the expression of LC opsin mRNA determined by real-time RT–PCR was low in the early morning and high in the late afternoon, similar to the fluctuation of behavioral cone sensitivity. This rhythm of LC opsin mRNA expression, however, dampened out gradually in constant conditions. After 24 h of constant light (LL), the expression of LC opsin mRNA dropped to levels similar to those determined in the early morning in control animals. By contrast, when the zebrafish were kept in constant dark (DD), the expression of LC opsin mRNA increased, to levels about 30-fold higher than the expression in the early morning in control animals. This day–night fluctuation in LC opsin mRNA expression was correlated to changes in opsin density in the outer segment of cone photoreceptor cells. Microspectrophotometry (MSP)measurements found significant differences in red cone outer segment optical density with a rhythm following the behavioral sensitivity. Furthermore,dopamine modulated the circadian rhythms in expression of LC opsin mRNA. Administration of dopamine increased LC opsin mRNA expression, but only in the early morning.
Desalting, Concentration, and Buffer Exchange by Dialysis and Ultrafiltration
Authors: Phillips Allen T. , Signs Mark W.
Published: January 2005

This unit includes a variety of dialysis and ultrafiltration techniques that can be used for desalting, concentration, or buffer exchange. Standard dialysis by diffusion across cellulose tubing is described as a technique for desalting or buffer exchange. Ultrafiltration under pressure can be used either for concentrating protein or, where the sample volume is replenished with a desired buffer, for desalting/buffer exchange (i.e., diafiltration). A variation is ultrafiltration by tangential flow, which serves the same purposes as ultrafiltration under pressure but is better suited to handling large volumes of solution. Yet another variation is an ultrafiltration technique employing centrifugal microconcentrators, which allows concentration of very small volumes of solution.
Extraction of Proteins from Plant Tissues
Authors: Laing William , Christeller John
Published: January 2005

A basic protocol is described for extracting protein from plants. Suggestions are included for overcoming some of the common obstacles encountered (e.g., acidity, phenolics, cell walls).
Preparation and Extraction of Insoluble (Inclusion‐Body) Proteins from Escherichia coli
Authors: Palmer Ira , Wingfield Paul T.
Published: January 2005

High‐level expression of many recombinant proteins in Escherichia coli leads to the formation of highly aggregated protein commonly referred to as inclusion bodies. Inclusion bodies are normally formed in the cytoplasm; alternatively, if a secretion vector is used, they can form in the periplasmic space. Inclusion bodies can be recovered from cell lysates and this unit describes preparation of washed pellets and solubilization of the protein using guanidine⋅HCl. The extracted protein, which is unfolded, is either directly folded as described in UNIT here or further purified by gel filtration in the presence of guanidine⋅HCl as idescribed here. A support protocol describes the removal of guanidine⋅HCl from column fractions so they can be monitored by SDS‐PAGE.
Determining the Fluorescence Spectrum of a Protein
Authors: Pain Roger H.
Published: January 2005

Fluorescence spectra of proteins are determined chiefly by the polarity of the environment of the tryptophan and tyrosine residues and by their specific interactions. A thorough consideration of fluorescence spectrometers and their calibration is provided along with important information regarding spectrometer cells, buffers and clarification of samples. Protocols are provided for recording fluorescence spectra and for measuring fluorescence quenching to probe the accessibility of tryptophan residues to small molecules (to yield information about the structural environment of the tryptophan). The technique involves quantifying the decrease in protein fluorescence intensity in the presence of increasing concentrations of quencher, followed by analysis of the data to give details of the interaction of the quencher with the tryptophan residue. Finally, agives details on how to interpret fluorescence spectra.