bluuebunny/crossref_metadata_2025 huggingface dataset:
Elevated Brain 5‐Hydroxytryptophol Levels in Experimental Portal‐Systemic Encephalopathy
Authors: Bergqvist Peter B. F. , Some Margareta , Apelqvist Gustav , Helander Anders , Bengtsson Finn
Published: March 2009

Abstract: Brain tissue levels of the two serotonin metabolites 5‐hydroxytryptophol and 5‐hydroxyindole‐3‐acetic acid (5‐HIAA) were measured in porta‐caval shunted rats, an in vivo model of portal‐systemic encephalopathy. An intraperitoneal challenge of L‐tryptophan (280 mg/kg body weight) to sham‐operated rats was also instituted to increase the brain serotonin metabolism in these rats. The results revealed significant increases in 5‐hydroxytryptophol (by 31%) and 5‐HIAA (by 87%) brain levels in porta‐caval shunted rats as compared to sham‐operated controls. The brain 5‐hydroxytryptophol‐to‐5‐HIAA ratio was lower in the porta‐caval shunted rats. The 5‐hydroxytryptophol levels in sham rats after the L‐tryptophan challenge were intermediate between the porta‐caval shunted and sham rats but not statistically significant for either group. These results suggest that increased brain 5‐hydroxytryptophol levels might be associated with the pathogenesis of portal‐systemic encephalopathy. Further, the elevated brain 5‐hydroxytryptophol levels in experimental portal‐systemic encephalopathy are probably a result of the increased brain serotonin metabolism prevailing in this condition rather than changes in the brain redox potential.
Renal Tolerability Profile of Novel, Potent Bisphosphonates in Two Short‐Term Rat Models
Authors: Green Jonathan R. , Seltenmeyer Yves , Jaeggi Knut A. , Widler Leo
Published: March 2009

Abstract: Bisphosphonates are used clinically to inhibit bone resorption but they may also cause renal damage. For the profiling of new, potent bisphosphonates, their adverse renal effects were investigated in 2 rat models. In the first model, bisphosphonate was repeatedly injected (1 mg/kg, subcutaneously) over 2 weeks and the urinary excretion of malate dehydrogenase was monitored to assess nephrotoxic potential. Of the 6 new compounds tested, 3 markedly elevated malate dehydrogenase whereas 3 others caused only minor changes similar to those observed with 6 reference bisphosphonates that are already used clinically. On the basis of a therapeutic index (inhibition of bone resorption versus renal effects) 7‐180 fold greater than that of other analogues, the compound CGP 42446 was further profiled. In the second model, CGP 42446 or pamidronate was infused (1.5‐50 mg/kg, intravenously) into anaesthetized rats and the serum urea concentration was monitored as an indicator of renal dysfunction. Both compounds elevated serum urea in a time‐and dose‐dependent manner, but the ED100 value for CGP 42446 was 3.8‐fold higher than that of pamidronate. It is concluded that CGP 42446 (zoledronate) has a low nephrotoxic potential and can be further developed as a new, potent inhibitor of bone resorption.
Carbonyl Reduction of Daunorubicin in Rabbit Liver and Heart
Authors: Pröpper Dirk , Maser Edmund
Published: March 2009

Abstract:A major problem of anthracycline anticancer treatment are the cardiotoxic side effects associated with drug therapy. Increased attention has recently been focused on the 13‐hydroxy anthracycline metabolites which are formed by carbonyl reduction of the parent drug as contributing to cardiotoxicity. By using daunorubicin as a reference molecule, our study was designed to quantitatively evaluate and compare the extent of anthracycline carbonyl reduction of liver and heart at the physiological important pH 7.4, and to identify the enzyme(s) involved under these conditions. The present kinetic data indicate that only one single enzyme system is active in cytosol of both tissues. According to its specific inhibition by quercitrin and the failure of a barbiturate to affect activity the enzyme responsible for daunorubicin carbonyl reduction in these fractions is carbonyl reductase (EC 1.1.1.184). Since the KMvalues differ significantly from each other, it is suggested that liver and heart express different isoforms of this enzyme. We failed to detect any specific daunorubicin carbonyl reductase activity in both microsomal fractions. Intrinsic clearance values revealed that liver has obviously 350‐times the capacity of total 13‐hydroxy metabolite formation compared to heart. This indicates that under a therapeutic regimen 13‐hydroxy anthracyclines of hepatic origin would add to the metabolites that are produced by the heart itself. The prevention of these metabolites may represent a potential approach for enhancing the safety and efficacy of anthracycline chemotherapy.
Bioavailability of Enrofloxacin after Oral Administration to Fed and Fasted Pigs
Authors: Nielsen Poul , Gyrd‐Hansen Nils
Published: March 2009

Abstract:The disposition of enrofloxacin was measured after intravenous and oral administration to pigs. Eight clinically healthy pigs weighing 25 to 40 kg received a dose of 5 mg/kg intravenously and 10 mg/kg orally in both a fasted and a fed condition in a three‐way cross‐over design. Enrofloxacin was present in plasma for up to 72 hr after both intravenous and oral administration to fasted as well as fed pigs. The steady state volume of distribution was determined to 3.9±0.5 1/kg body weight which indicates that enrofloxacin was widely distributed in the body. The bioavailability was determined to 83±13% in fed and to 101±32% in fasted pigs. Based on the bioavailability and the resulting plasma concentrations it is concluded that a therapeutically active concentration for the most common porcine microbial pathogens are maintained for at least 24 hr after oral administration of 10 mg/kg body weight to fasted as well as to fed pigs. Ciprofloxacin which is an active metabolite of enrofloxacin was observed in plasma samples from all treated pigs, but the concentration never exceeded 0.1 μg/ml. During the first 24 hr after the administration of enrofloxacin the concentration of the metabolite made up less than 10% of the corresponding concentration of the parent compound.
T25: A Simplified Carcinogenic Potency Index: Description of the System and Study of Correlations between Carcinogenic Potency and Species/Site Specificity and Mutagenicity
Authors: Dybing Erik , Sanner Tore , Roelfzema Henk , Kroese Dinant , Tennant Raymond W.
Published: March 2009

Abstract: A simplified carcinogenic potency index, the T25, is proposed as a practical method for the inclusion of potency considerations in carcinogen classification systems. The T25 is the chronic daily dose in mg per kg bodyweight which will give 25% of the animals tumours at a specific tissue site, after correction for spontaneous incidence, within the standard life span of that species. Calculated T25 values of a set of 113 US National Cancer Institute/National Toxicology Program (NC/NTP) carcinogens showed excellent correlation (correlation coefficient 0.96, P<0.0001) with the carcinogenic potency index TD50 of Peto et al. (1984). The mean of T25 values for 51 transspecies, multiple common site NCI/NTP carcinogens were 10‐fold lower than those for 62 NCI/NTP single species, single site carcinogens. For these 113 carcinogens, the mean T25 values were approximately 3‐fold lower for agents that were also mutagenic in Salmonella compared to the non‐mutagenic agents.
Modulation of the Megakaryoblastic Dami Cell Line Differentiation by Phosphodiesterase Inhibitors and Imidazo[1,2‐a]pyrazine Derivatives
Authors: Zurbonsen Katja , Michel Alain , Vittet Daniel , Bonnet Pierre‐Antoine , Chevillard Claude
Published: March 2009

Abstract:Phosphodiesterase inhibitors have been shown to modulate cell differentiation. We have previously shown that a series of imidazo[1,2‐a]pyrazine derivatives displayed inhibitory effects on phosphodiesterase isoenzymes types III, IV and V isolated from Dami cells and on Dami cell growth. In the present study we have investigated the effect of these derivatives on the expression of two differentiation markers, glycoproteins Ib and IIb/IIIa of the human megakaryoblastic leukaemic Dami cell line in comparison to those elicited by 3‐isobutyl‐1‐methylxanthine and selective phosphodiesterase inhibitors of types I (8‐methoxymethyl‐1‐methyl‐3‐(2‐methylpropyl) xanthine), III (Milrinone), IV (RO‐201724) and V (Zaprinast). Imidazo[1,2‐a]pyrazine derivatives, 3‐isobutyl‐1‐methylxanthine and selective phosphodiesterase inhibitors, except 8‐methoxymethyl‐1‐methyl‐3‐(2‐methylpropyl) xanthine, decreased glycoprotein Ib expression. SCA40, SCA41, SCA44 and 3‐isobutyl‐1‐methylxanthine but not the other compounds affected the expression of glycoprotein IIb/IIIa in a positive manner. The effects of imidazo[1,2‐a]pyrazine derivatives on glycoprotein expression appeared to be related to their phosphodiesterase inhibitory potency.
On the High Affinity of 8‐Cyclohexylcaffeine for the Presynaptic Inhibitory Adenosine Receptor Present in Rat Motor Nerve Terminals
Authors: Lobo M. Gnaça B. , Oliveira Dulce G. , Sebastião Ana M. , Ribeiro J. Alexandre
Published: March 2009

Abstract:Rat neuromuscular junction was used to study the characteristics of presynaptic A1adenosine receptors. We investigated the ability of the 8‐substituted caffeine, 8‐cyclohexylcaffeine (CHC), as well as of 1,3,8‐substituted xanthines, 1,3‐dipropyl‐8‐p‐sulfophenylxanthine (DPSPX) and 8‐p‐sulfophenyl‐1‐isoamyl‐3‐isobutylxanthine (SPIIBX) to antagonize the inhibitory effect of 2‐chloroadenosine on the amplitude of nerve‐evoked twitches of the rat phrenic‐hemidiaphragm, and we compared the affinity of these xanthines with that of 1,3‐dipropyl‐8‐cyclopenthylxanthine (DPCPX). CHC, DPSPX and SPIIBX in a near parallel manner shifted to the right the log concentration‐response curve for the inhibitory effect of 2‐chloroadenosine on nerve‐evoked twitch amplitude. Linear Schild plots with slopes near to unity were obtained for all these xanthines. The order of potency of the xanthines was DPCPX (Ki=0.53 nM) >DPSPX (38 nM) ≈CHC (41 nM) >SPIIBX (404 nM). The affinities of DPSPX and SPIIBX for the A1receptor at the rat neuromuscular junction are in agreement with the affinities described for A1receptors at brain membranes. The now reported affinity of CHC for the presynaptic A1receptor is 683 times higher than that obtained in binding studies in rat brain membranes, and is only 49 times higher than that obtained in functional assays (adenylate cyclase activity) in non‐neuronal preparations (rat fat cells).
The Göttingen Minipig in Pharmacology and Toxicology
Authors: Bollen Peter , Ellegaard Lars
Published: March 2009

Abstract:Pigs traditionally are used in surgical and physiological research. Since the development of the Minnesota minipig in 1949 at the Hormel Institute (USA), miniature pigs have been introduced as a model in pharmacology and toxicology, because ofscientific, economicandethicalreasons.
Health Status of Experimental Pigs
Authors: Hansen Axel Kornerup
Published: March 2009

Abstract: Due to the increase in the use of pigs in research, there seems to be a demand from the scientific community for an improved quality of experimental pigs. Germ‐free pigs may be produced by removing fully developed foetuses aseptically from the uterus by hysterectomy and rearing them in isolators, alternatively embryo transfer may be used. Such rederived pigs may be maintained in isolators in the gnotobiotic status or gnotobiotic pigs may be used for the upstart of a breeding colony housed under conditions (i.e. a barrier) protecting them against certain agents, for which a monitoring system is operated. Different categories of barrier‐bred pigs, such as, minimal disease, specific pathogen‐free and microbiologically defined, are presented and differences between these categories are discussed. Basic principles of health monitoring in pigs, e.g. sample size, testing frequency and methods, are outlined. It is discussed how the lack of positive findings in health monitoring may be due to other factors than freedom from infection, e.g. treatment with antibiotics or a statistically invalid examination. Finally, the risk of infection with certain porcine agents when housing barrier‐bred pigs in conventional experimental units is discussed.
Anaesthesia and Basic Experimental Surgery of Minipigs
Authors: Svendsen Per
Published: March 2009

Abstract: Minipigs tolerate anaesthesia very well. The only disadvantages are the difficulties in performing venous puncture and endotracheal intubation. To overcome these the animals should be well sedated prior to induction by intravenous injection, and deeply anaesthetized prior to the introduction of the endotracheal tube. Anaesthetic regimen and several basic experimental surgical techniques will be practised.
Morphine‐6‐glucuronide‐Induced Locomotor Stimulation in Mice: Role of Opioid Receptors
Authors: Grung Merete , Skurtvcit Svetlana , Aasmundstad Tor A. , Handal Marte , Alkana Ron L. , Mørland Jørg
Published: March 2009

Abstract:Morphine‐6β‐glucuronide is a major metabolite of morphine with potent analgesic actions. To explore the importance of this opiate when administered as a drug by its own or in morphine action, we studied the locomotor activity response to morphine and morphine‐6‐glucuronide in drug‐naive C57 BL/6JBom mice. The effects of administration of the two opiates on a battery of 7 different locomotor activities were studied and compared to saline controls. A dose of 20 μmol/kg morphine‐6‐glucuronide resulted in more locomotion than the same dose of morphine, while at higher doses (up to 120 umol/kg), similar increases for most locomotor behaviours were recorded for both drugs. Pretreatment with naltrindole indicated that the S‐receptors play an equivalent but minor role in mediating both morphinc‐6‐glucuronide and morphine hyperlocomotion. Administration of high naltrexone doses (10 mg/kg) completely abolished the locomotor stimulation induced by both opiates. However, at intermediate naltrexone doses of 0.25 and 0.5 mg/kg, morphine‐induced behaviours was completely inhibited while morphine‐6‐glueuronide induced behaviours demonstrated partial resistance to naltrexone inhibition. The μ1‐specifie receptor antagonist naloxonazine caused 75% reduction of morphine induced behaviours and only 50% inhibition of morphine‐6‐glucuronide induced behaviors. Taken together our observations indicated general similarity but also marked differences between morphine and morphine‐6‐glucuronide with respect to opiate receptors mediating the locomotor stimulatory effect.
Comparative Studies on the Induction of Muscle Contracture in Mouse Diaphragm and Ca2+Release from Sarcoplasmic Reticulum Vesicles by Organotin Compounds
Authors: Kang Jaw‐Jou , Liu Shing‐Hwa , Chen I‐Ling , Cheng Yu‐Wen , Lin‐Shiau Shoei‐Yn
Published: March 2009

Abstract:Effects of organotins. including triethyltin and tributyltin, on skeletal muscle were studied with diaphragm and isolated sarcoplasmic reticulum membrane vesicles. Triethyltin induced muscle contracture in mouse diaphragm while tributyltin had comparatively less potency and efficacy in inducing the muscle contracture. The contracture induced by tributyltin was inhibited when the diaphragm was pretreated with low Ca2+medium or caffeine while the contracture induced by triethyltin persisted in the Ca2+‐free medium but was inhibited by pretreatment of caffeine. Pretreatment of dithiothreilol blocked the contracture induced by tributyltin but not that by triethyltin. Triethyltin dose‐dependently induced Ca2+release from sarcoplasmic reticulum vesicles and inhibited the Ca2+‐ATPase activity. These results suggested that triethyltin induced contracture in mouse diaphragm was mainly by induction of Ca2+release and inhibition of Ca2+uptake of the internal Ca2+storage site the sarcoplasmic reticulum, while the tributyltin induced contracture might be due to enhancement of extracellular Ca2+influx which further induce the release of internal Ca2+through the Ca2+‐induced Ca2+release mechanism.
Nitric Oxide Donor NOR 3 Inhibits Ketogenesis from Oleate in Isolated Rat Hepatocytes by a Cyclic GMP‐Independent Mechanism
Authors: Nomura Takahide , Ohtsuki Masatsugu , Matsui Shigeru , Sumi‐Ichinose Chiho , Nomura Hiroko , Hagino Yasumichi
Published: March 2009

Abstract:Studies were conducted to clarify the effects of nitric oxide donors NOR 3 (±)‐(E)‐ethyl‐2‐[(E)‐hydroxyimino]‐5‐nitro‐3‐hexeneamide, FK409), S1N‐1 (3‐morpholinosydnonimine) and SNAP (S‐nitroso‐N‐acetylpenieillarnine) on the accumulation of cGMP and cAMP and Ca2+mobilization as well as ketogenesis from oleate in isolated rat hepatocytes. NOR 3 caused inhibition of ketogenesis from oleate along with stimulation of cGMP accumulation in rat hepatocytes, whereas SIN‐1 and SNAP exerted no effect on ketogenesis despite their marked stimulation of cGMP accumulation. Although the nitric oxide trapping agent, carboxy‐PTIO (2‐phenyl‐4,4,5,5‐tetramethylimidazoline‐l‐oxyl 3‐oxide), antagonized the stimulation by NOR 3 of cGMP accumulation, it failed to modulate the anti‐ketogenic action of NOR 3. Furthermore, neither 8‐bromoguanosine‐3′,5′‐cyclic monophosphate norN2,2′‐O‐dibutyrylguanosine‐3′,5′‐cyclic monophosphate mimicked the anti‐ketogenic action of NOR 3. It is concluded in the present study that NOR 3‐induced inhibition of ketogenesis in rat hepatocytes is not mediated by cGMP. The present study revealed that the remaining structure of NOR 3 from which nitric oxide had been spontaneously released had no anti‐ketogenic action. We first and clearly demonstrated that nitrite production was dramatically enhanced when NOR 3 was incubated in the presence of rat hepatocytes. The mechanism whereby NOR 3 inhibits ketogenesis in rat hepatocytes will be discussed.
Anticonvulsant Profile of 4‐Amino‐(2‐methyl‐4‐aminophenyl)benzamide in Mice and Rats
Authors: Kanyonyo Martial R. , Poupaert Jacques H. , Lambert Didier M.
Published: March 2009

Abstract: An original ameltolide analogue 4‐amino‐(2‐methyl‐4‐aminophcnyl)benzamide, in which a second amino group has been introduced, was synthesized and evaluated for anticonvulsant activity. After intraperitoneal administration to mice, 4‐amino‐(2‐methyl‐4‐aminophenyl)benzamide was found active in the maximal electroshock seizure test and against the tonic seizures elicited either by bicuculline or 3‐mercaptopropionic acid. 4‐amino‐(2‐methyl‐4‐arainophenyl)benzamidc (4A‐2M4A‐PB) gave anti maximal electroshock seizures ED50, of 63 umol/kg (15.4 mg/kg) and a TD50 of 676 μmol/kg (163 mg/kg), yielding a PI of 10.7: the potency is similar to that of the 4‐amino‐(2‐rnethyl‐3‐aminophenyl)phthalimide (4‐A‐2M3A‐PP), superior to that of 4‐amino‐(2,6‐dimethylphenyl)phlhaiimide (4A‐2,6‐DMPP), close to that of phenytoin and carbamazepine and inferior to that of ameltolide. 4A‐2M4A‐PB with an ED50 of 41 [28‐60] μmol/kg (9.9 mg/kg) is as active after oral administration to rats as carbamazepine, more active than ameltolide, 4‐A‐2M3A‐PP and phenytoin and slightly less active than the 4A‐2,6‐DMPP. The introduction of a second amino group on the substituted phenyl ring does not affect drastically the anticonvulsant potency after intraperitoneal administration to mice; moreover, it seems to enhance the activity after oral administration. 4A‐2M4A‐PB is a good candidate both for further pharmacokinetic studies and for the study of the precise mechanism of action.
Metabolic Interaction of n‐Hexane and Methyl Ethyl Ketone in vitro in a Head Space Rat Liver S9 Vial Equilibration System
Authors: Mortensen Bjarte , Zahlsen Kolbjørn , Nilsen Odd G.
Published: March 2009

Abstract: Methyl ethyl ketone pretreatment induced rat liver cytochrome P450 and increased significantly the in vitro metabolism of n‐hexane and the formation of 2,5‐hexanedione in rat liver S9. No significant changes were, however, found in the levels of the intermediate metabolites 2‐hexanol, 2,5‐hexanedioI or methyl n‐butyl ketone. Methyl ethyl ketone added in vitro to untreated (non‐induced) liver S9 inhibited in a non‐competitive pattern the metabolism of n‐hexane and decreased significantly and in a dose‐dependent way the levels of methyl n‐butyl ketone and 2,5‐hexanedione. When methyl ethyl ketone and n‐hexane were added in vitro to in vivo methyl ethyl ketone pretreated (induced) liver S9, the significant increase in the formation of 2,5‐hexanedione was maintained, an increase which was only to a minor extent influenced by the in vitro addition of methyl ethyl ketone. These findings are in agreement with an in vivo induction by methyl ethyl ketone of key enzyme(s) in a generally minor metabolic pathway for the conversion of n‐hexane to 2,5‐hexanedione in rat liver, a pathway which is not influenced by the presence of methyl ethyl ketone itself. The results obtained in this study indicate that the head space equilibration technique is well suited for screening studies of metabolic interactions between organic solvents.
Liver Damage Induced by Bile Duct Ligation Affects CYP Isoenzymes Differently in Rats
Authors: Tateishi Tomonori , Watanabe Minoru , Nakura Hironori , Tanaka Masami , Kumai Toshio , Kobayashi Shinichi
Published: March 2009

Abstract:We examined the influence of liver damage induced by bile ducl ligation on the activity and the expression of hepatic cytochrome P450 (CYP) IA. 2B, 2C6. 2C11. 2E1 and 3A2 in male Sprague‐Dawley rats. In the ligation group. testosterone 2α‐, 16α‐. and 6β‐hydroxylase activities were severely decreased, whereas ethoxyresorufin O‐deethylase and progesterone 21‐hydroxylase activities relatively remained. Pentoxyresorulin O‐deethylase and chlorzoxazone 6‐hydroxylase activities were reduced to approximately one thirds those of control. The protein contents of these isoenzymes expressed in hepatic microsomes of the ligation group were decreased to 45%. 32%. 79%, 13%, 58%, and 23% of control for CYP1A, 2B, 2C6, 2C11, 2E1 and 3A2. respectively. The rank order of magnitude of the influence of bile duct ligation on CYP isoenzymes, assessed by the reduction in the enzyme activity and the protein content, corresponded with each other except CYP1A. The reduction of the enzyme activities significantly correlated with the reduction in the protein contents of different isoenzymes. These results suggested that bile duct ligation affected CYP isoenzyme activities and contents with different extent.
Acetaminophen Protection Against Estramustine‐Induced Cytotoxicity on Cultured Fibroblasts
Authors: Heldestad Åsa , Jonsborg Sonny , Henriksson Roger , Grankvist Kjell
Published: March 2009

Abstract: Two commonly used analgesics, ibuprofen and acetaminophen (paracetamol) were investigated for possible influence on Chinese hamster fibroblast (V‐79) cytotoxicity (measured by cells cloning ability and 86Rb accumulation) of the antineoplastic drugs estramustine and bleomycin in vitro. Fibroblast exposure to estramustine (80 mg/1) or bleomycin (50 mg/1), for 1 or 24 hr, reduced the number of surviving clones to approximately 35% and 50% respectively. Acetaminophen (10 or 100 mg/1), but not ibuprofen, significantly increased the number of surviving clones with estramustine. The analgesics had no effect on bleomycin cytotoxicity. The uptake of 86Rb+ (K+ analogue) by V‐79 cells was reduced after incubation with 80 mg/1 estramustine phosphate. Acetaminophen (30 mg/1) but not 10 mg/1 acetaminophen or ibuprofen (30 or 100 mg/1), significantly protected against estramustine reduction of 86Rb accumulation. Acetaminophen inhibition of estramustine cytotoxicity is suggested to be due to reversal of estramustinc‐induced inhibition of cellular potassium channel ion transport.
Prolactin Response to Bromperidol Treatment in Schizophrenic Patients
Authors: Yasui Norio , Kondo Tsuyoshi , Otani Koichi , Ishida Masayuki , Mihara Kazuo , Suzuki Akihito , Kaneko Sunao , Inoue Yoshimasa
Published: March 2009

Abstract:The prolactin response to an antipsychotic drug, bromperidol was studied in 24 schizophrenic in‐patients (13 males, 11 females). Eight patients were given 6 mg/day, 8 were given 12 mg/day and 8 were given 18 mg/day. Duration of treatment was 3 weeks. Plasma concentrations of bromperidol and reduced bromperidol were measured by high‐performance liquid chromatography, and that of prolactin was measured by radioimmunoassay. Bromperidol treatment significantly (P < 0.01) increased plasma concentration of prolactin each week. The mean ± S. D. of the ±‐prolactin (the mean concentration during treatment minus the pretreatment concentration) was 13.3 ± 12.4 ng/ml. Multiple regression analysis showed that the δ‐prolactin concentration was significantly greater in females than in males (P < 0.05) and correlated to plasma concentrations of bromperidol (P < 0.001) and reduced bromperidol (P < 0.0001). These results suggest that the prolactin response to bromperidol treatment depend on plasma concentrations of both bromperidol and reduced bromperidol and gender, and that reduced bromperidol is involved in the pharmacological effects during bromperidol treatment.
Ketobemidone plus (RS)‐3‐dimethylamino‐1,1‐diphenylbut‐1‐ene (A29) is More Potent at NMDA Receptors than Ketobemidone Alone: Evidence for A29 as a Non‐Competitive NMDA Receptor Antagonist
Authors: Ebert Bjarke , Thorkildsen Christian , Andersen Steen
Published: March 2009

Abstract:The opioid, ketobemidone, has previously been shown to be a non‐competitive N‐methyl‐D‐aspartate (NMDA) receptor antagonist. In Denmark, ketobemidone is available in a formulation which contains ketobemidone and a spasmolytic compound, (RS)‐3‐dimethylamino‐l,l‐diphenylbut‐l‐ene, hydrochloride (A29), in a one to five ratio. Usingin vitroreceptor binding techniques and anin vitroelectrophysiological preparation consisting of rat cerebral cortex, we have characterized the interaction between A29 and the different glutamale receptor subtypes. A29 selectively inhibited binding of the non‐competitive NMDA receptor antagonist3H‐MK‐801 with a Kivalue 16 ± 4.5 μM, but was inactive in assays measuring affinities for other glutamate receptors. In agreement with the binding studies, A29 was found to selectively inhibit responses to NMDA in the rat cortical wedge preparation, whereas responses to kainate and AMPA were unaffected. Analysis of dose response curves showed A29 to be a NMDA receptor antagonist with an IC50value of 100 μM versus responses to 10 μM NMDA. The inhibitory effects of ketobemidone and A29 on responses to 10 uM NMDA were additive. These data show that the combination of A29 and ketobemidone exert more potent antagonism at the NMDA receptor than does ketobemidone alone.
Evidence for the Activation of Vitamin D Compounds in the Skin by Side–Chain Hydroxylation
Authors: Gniadecki Robert , Calverley Martin J.
Published: March 2009

Abstract: KH 1060 is the 20–epi–22–oxa–24a–homo–26, 27–dimethyl analogue of the natural hormone, la,25–dihydroxyvitamin D3 (1α, 25(OH)2D3). We have previously shown that after topical application in hairless mice both KH 1060 and 1α, 25(OH)2D3 cause epidermal hyperproliferation. MC 1582 differs from KH 1060 by the lack of hydroxyl group in the side chain which is required for receptor binding. We found that MC 1582 strongly stimulates epidermal hyperplasia in hairless mice after topical application in vivo, approaching in potency KH 1060. A similar, although much weaker response was also obtained with 1α–hydroxyvitamin D3 (1α(OH)D3). Since only the vitamin D compounds which possess hydroxyl groups both in the position 1α and in the side chain, bind to the vitamin D receptor, we suggest that a local metabolism of MC 1582 and 1α(OH)D3 takes place in the skin to the active, side–chain–hydroxylated species, probably to KH 1060 and 1α, 25(OH)2D3. This study suggests that 1α hydroxylated prodrugs may be of use in the dermatological treatment of the future.
Sustained Cholecystokinin–B/Gastrin Receptor Blockade Does Not Impair Basal or Histamine–Stimulated Acid Secretion in Chronic Gastric Fistula Rats
Authors: Ding Xi–Qin , Kitano Masayuki , Håkanson Rolf
Published: March 2009

Abstract:Gastrin is a physiologically important secrelagogue. It is thought to stimulate parietal cells indirectly by mobilizing histamine from enterochromaffin–like (ECL) cells in the oxyntic mucosa. Gastrin stimulates the secretory activity and growth of the ECL cells via an action on cholecystokinin–B/gastrin receptors. Acute cholecystokinin–B/gastrin receptor blockade is known to inhibit gastrin–stimulated acid secretion but whether sustained cholecystokinin–B/gastrin receptor blockade will impair basal, gastrin– and histamine–stimulated acid secretion remains uncertain. The present study was designed to study the effect of long–term (4 weeks) cholecystokinin–B/gastrin receptor blockade on basal and stimulated acid secretion in conscious rats. The selective cholecystokinin–B/gastrin receptor antagonist YM022 (3 μmol kg–1hr–l) was given to gastric fistula rats by continuous subcutaneous infusion via osmotic minipumps for various times from 2 hr to 4 weeks. Basal, gastrin– and histamine– stimulated acid secretion were examined during and after cessation of treatment. Basal and histamine–stimulated acid secretion was not affected by YM022 during the 4 week period of administration, whereas gastrin–induced acid secretion was inhibited. YM022 induced hypergastrinaemia in freely fed rats but did not affect the serum gastrin level in fasted rats. The serum gastrin concentration and gastrin–induced acid secretion returned to control levels 3–7 days after termination of YM022 administration.
Antiproliferative Activity and Phototoxicity of some Methyl Derivatives of 5–Methoxypsoralen and 5–Methoxyangelicin
Authors: Conconi Maria Teresa , Montesi Francesco , Parnigotto Pier P.
Published: March 2009

Abstract: The in vitro antiproliferative activity and in vivo phototoxicity of some methyl derivatives of 5–methoxypsoralen and 5–methoxyangelicin, i.e. 4,4′–dimethyl–5–methoxyangelicin (compound I), 3,4′–dimethyl–5–methoxyangelicin (compound II), 4,4′–dimethyl–5–methoxypsoralen (compound III); and 3.4′–dimethyl–5–methoxypsoralen (compound IV), have been investigated. The effects of the compounds were evaluated in vitro on HL60 and A431 cells, using 5–methoxypsoralen as the reference compound. In both cell lines compound I, II and III showed better antiproliferative activity than compound IV and 5–methoxypsoralen. Scanning electron microscopy revealed that all the compounds induced the formation of blebs and blisters on a A431 cell surface. Significant variations in the nuclear area strictly related to the toxicity of the compounds have been shown in both cell lines. Skin irritancy in vivo was evaluated by mean of histopathological responses on guinea–pig skin. For each compound a damage index was determined by morphometrical analysis of empty spaces in the epidermis. Histopathology revealed skin phototoxicity of compounds which lacked erythemogenic activity by visual scoring. By coupling cytotoxicity data in vitro to skin sensitization ones in vivo, compound I proved a promising candidate for use in clinical trials since due to a high inhibitory effect on the growth of human cell lines coupled to low skin phototoxicity.
Developmental Expression of Cytochrome P450 Enzymes in Human Liver
Authors: Hakkola Jukka , Tanaka Einosuke , Pelkonen Olavi
Published: March 2009

Abstract:Drug–metabolizing cytochrome P450 enzymes, the major phase I enzymes, are active in human liver already at very early stages of intrauterine development, although presumably at fairly low concentrations and in low numbers. During maturation, these enzymes go through various developmental programmes towards adulthood. The major increase both in abundance as well as in number of different enzymes takes place after birth, probably during the first year of life. Detailed information concerning these developmental changes is still limited. The major drug–metabolizing P450 enzymes appear to be primarily members of the CYP3A subfamily in all stages of development. The balance between different members of this subfamily, however, undergoes significant switches from the foetal predominant CYP3A7 to the major adult form CYP3A4. The ontogeny of the other cytochrome P450 enzymes is less well characterized, but the major switchon appears to occur mainly after birth. Developmental expression of P450 enzymes is one of the key factors determining the pharmacokinetic status of developing individuals both pre– and postnatally.
Effect of Stem Cell Factor, Interleukin–6, Nitric Oxide and Transforming Growth Factor–β on the Osteoclast Differentiation Induced by 1α,25–(OH)2D3in Primary Murine Bone Marrow Cultures
Authors: Chae Han–Jung , Park Rae–Kil , Kang Jang–Sook , Shin Hyung–Shik , Kim Sang–Chul , Chung Hun–Taeg , Son Dong–Whan , Ko Kun–IL , Kim Jae–Baek , Park Young–Chul , Kim Hyung–Ryong
Published: March 2009

Abstract:Osteotropic hormones and cytokines are involved in the differentiation of osteoclast progenitors from haematopoietic stem cells to multinucleated osteoclasts which mediate bone resorption. Stem cell factor, interleukin–6, nitric oxide, and transforming growth factor–β are implicated in the regulation of bone resorption by osteoclast. We test whether stem cell factor, interleukin–6, nitric oxide, and transforming growth factor–β affect the generation of osteoclast–like multinucleated cells induced by 1α,25–(OH)2D3. 1α,25–(OH)2D3increases the generation of osteoclast–like cells retaining osteoclast characteristics including multinuclearity and positive staining for tartrate–resistant acid phosphatase. Combined treatment of stem cell factor with interleukin–6 synergistically potentiates the ability of 1α,25–(OH)2D3to generate tartrate–resistant acid phosphatase–positive multinucleated cells. However, either stem cell factor or interleukin–6 alone does not induce the generation of tartrate–resistant acid phosphatase–positive multinucleated cells. Transforming growth factor–β produces a biphasic effect on osteoclast generation induced by 1α,25–(OH)2D3. Transforming growth factor–β stimulates osteoclast generation at low concentration (0.1 ng/ml) whereas it suppresses the formation of osteoclast–like cell at higher concentration (1 ng/ml). Sodium nitroprusside, a donor of nitric oxide, almost completely inhibits the generation of 1α,25–(OH)2D3–induced osteoclast at high concentration (100 μM), but it significantly enhances the osteoclast generation at low concentrations (3 μM). These results suggest that stem cell factor, interleukin–6, transforming growth factor–β, and nitric oxide interact with 1α,25–(OH)2D3to modulate the differentiation of hematopoietic precursors toward committed osteoclast precursors.
Effect oft–Butylhydroperoxide on Chloride Secretion in Rat Tracheal Epithelia
Authors: Jung Jin Sup , Lee Jin Youn , Oh Sae Ock , Jang Phil Gum , Bae Hae Rahn , Kim Yong Keun , Lee Sang Ho
Published: March 2009

Abstract:Oxidative stress has been known to play important roles in various inflammatory diseases of lung such as allergic bronchitis, dust particle–induced inflammatory diseases, or chronic bronchitis. However, the effects of oxidants on Cl secretion in tracheal epithelia have not been determined. To examine the effects of oxidants on Cl–secretion of the airway epithelia rat tracheal epithelial cells were cultured on porous filters and short circuit current (Isc) was measured in an Ussing chamber system.t–Butylhydroperoxide, which was widely used as a model substance to study the mechanism of cell injury resulted from oxidative stress, induced a transient increase in Iscby dose–dependent manner. The response was not observed in Cl––free medium, and inhibited by 100 μM bumetanide. N(–Diphenyl–l,4–phenylene–diamine (DPPD, 5 μM), an inhibitor of lipid peroxidation, blocked thet–butylhydroperoxide response. Whent–butylhydroperoxide was added after the administration of forskolin or H–89, a protein kinase A inhibitor, thet–butylhydroperoxide–induee Iscincrease was abolished. Pretreatment of indomethacin (10 μM) completely inhibited thet–butylhydroperoxide response, but pretreatment of thapsigargin (1 μM) did not. t–Butylhydroperoxide induced gradual increases in cytosolic Ca2+level, and increased [3H]arachidonic acid release in the presence of thapsigargin. These results indicate thatt–butylhydroperoxide stimulates Cl–secretion via activation of phospholipase A2and subsequent production of cyclooxygenase metabolites by Ca2+–dependent and –independent mechanisms.
Growth Modulating Effects of Chlorinated Oleic Acid in Cell Cultures
Authors: Høstmark Arne T. , Lystad Einar , Jebens Einar , Skramstad Jan , Frøyen Paul
Published: March 2009

Abstract: Chlorinated fatty acids represent a major fraction of extractable, organically bound chlorine in fish. After dietary intake such fatty acids may be transferred from the mother to the foetus through the placenta, and via breast milk to the child. In the present work we have studied the effect of chlorinated oleic acid on the growth of three widely differing types of cells in culture. Chlorinated oleic acid inhibited growth of Human Microvascular Endothelial Cells (HMVEC), Immortilized Human Kidney Epithelial (IHKE) cells, and human Hepatoma cells (HepG2). The order of potency was: HMVEC > IHKE > HepG2. Vitamin E counteracted the inhibitory effect of chlorinated oleic acid on HepG2 cells, but did not significantly affect the fatty acid effect on HMVEC or IHKE. Defatted serum albumin stimulated the growth of HMVEC and IHKE. With HMVEC there was no major interaction between the effect of albumin and chlorinated oleic acid on cell growth. In contrast, with IHKE albumin at low concentration abolished the growth inhibiting effect of chlorinated oleic acid and appreciably counteracted growth inhibition by the fatty acid of HepG2 . We conclude that the growth modulation by chlorinated oleic acid and its interaction with vitamin E and albumin are cell specific.
Methamphetamine‐Induced Modification of Dopamine Metabolism in Cultured Striatal Astrocytes
Authors: Kita Taizo , Philbert Martin A. , Wagner George C. , Huang Jian , Lowndes Herbert E.
Published: March 2009

Abstract:The role of striatal astrocytes in the metabolic processing (by deamination) of methamphetamine‐released dopamine is not known. To investigate the relationship between methamphetamine and dopamine metabolism, we measured 6‐hydroxydopamine, dopamine and 3, 4‐dihydroxyphenylacetic acid (DOPAC) concentrations following methamphetamine treatment of cultured striatal astrocytes prepared from 1‐2 day‐old rats. Addition of low concentrations of dopamine (5×10–5to 5×10–4M) to cultured astrocytes increased DOPAC levels in a dose‐dependent fashion while higher concentrations (5×10–3to 10–2M) inhibited its metabolism and induced formation of 6‐hydroxydopamine. Under the same experimental conditions, 10–4M dopamine in combination with methamphetamine (10–5to 10–3M) inhibited DOPAC formation and increased dopamine levels in a dose‐dependent fashion, but the formation of intracellular 6‐hydroxydopamine was not evident. Deprenyl (10–5or 10–4M), an inhibitor of monoamine oxidase B, and pargyline (10–5or 10−4M), a non‐selective monoamine oxidase inhibitor, completely inhibited DOPAC formation and increased dopamine levels, while clorgyline (10−5or 10–4M), an inhibitor of monoamine oxidase‐A, only partially inhibited DOPAC formation (42 or 45% of control, respectively). These results support the hypothesis that methamphetamine inhibits monoamine oxidase and causes increases in dopamine levels in cultured striatal astrocytes.
Characterization of t‐Butyl Hydroperoxide Toxicity in Cultured Rat Cortical Neurones and Astrocytes
Authors: Abe Kazuho , Saito Hiroshi
Published: March 2009

Abstract: The present study investigates the toxicity of t‐butyl hydroperoxide (t‐BuOOH) in cultured rat cortical neurones and astrocytes. Both neurones and astrocytes were destroyed by exposure to t‐BuOOH in a time‐ and concentration‐dependent manner. Astrocytes were more resistant to destruction by hydrogen peroxide (H2O2) than neurones, but there was no difference in susceptibility to t‐BuOOH between neurones and astrocytes. The toxic effect of t‐BuOOH was significantly blocked by antioxidants, propyl gallate and trolox, but not by superoxide dismutase nor by H2O2‐scavengers, catalase and 4‐nitrophenylglyoxylic acid. These results suggest that t‐BuOOH toxicity is caused by oxidative stress unrelated to superoxide and H2O2. In addition, the toxic effect of t‐BuOOH was attenuated by the presence of iron chelators, deferoxamine and N, N, N′, N′,‐tetrakis(2‐pyridylmethyl)ethylenediamine, indicating the requirement of endogenous iron for t‐BuOOH toxicity.
Role of Microtubules in Glucose Uptake by C6 Glioma Cells
Authors: Singh Sant P. , Gao Yan , Singh Leela D. , Kunapuli S. P. , Ravindra Rudravajhala
Published: March 2009

Abstract: Drugs that influence tubulin function were used to investigate the role of microtubules in hexose uptake by C6 glioma cells. In C6 cells, colchicine and vinblastine (which inhibit tubulin polymerization) inhibited radioactive [3H]2‐deoxy‐D‐glucose uptake by about 30%. Paclitaxel (which promotes tubulin polymerization) stimulated hexose uptake by about 25%. To further demonstrate that microtubules play a role in hexose uptake, C6 cells were transfected with GLUT1 cDNA and then challenged with 100 nM paclitaxel. In GLUT1‐ transfected cells paclitaxel stimulated 2‐deoxy‐D‐glucose uptake by about 35%. To study the role of tubulin in agonist‐stimulated hexose uptake, the effect of colchicine on carbach‐ol‐induced uptake was next examined. Hexose uptake was increased with carbachol in concentration‐dependent manner which was abolished by pretreatment with colchicine. To examine the specificity of the inhibitory effect of colchicine on G protein‐mediated signal transduction pathway, the influence of colchicine on insulin (which acts via tyrosine kinase pathway) stimulation of 2‐deoxy‐D‐glucose uptake was investigated. Hexose uptake was increased by insulin in a concentration‐dependent manner which was unaffected by pretreatment with colchicine. These results suggest that microtubules are involved in basal and carbachol‐stimulated glucose uptake by C6 cells.
An Investigation of the Possible Interaction of Clomethiazole with Glutamate and Ion Channel Sites as an Explanation of its Neuroprotective Activity*
Authors: Green A. Richard , Misra Anil , Hewitt Kimberley E. , Snape Mike F. , Cross Alan J.
Published: March 2009

Abstract:The activity of the neuroprotective agent clomethiazole at glutamate and ion channel sites has been investigated. Dizocilpine (3.25 mg/kg intraperitoneally) provided almost total protection against the damage produced by infusion of N‐methyl‐DL‐ aspartate (NMDLA; 75 μg) into the right hippocampus. In contrast, clomethiazole (96 mg/kg intraperitoneally) was without effect. Using ligand binding techniques, no evidence was found for clomethiazole interacting with NMDA, AMPA or sigma binding sites. Clomethiazole did inhibit the stimulatory effect of the metabotropic glutamate receptor agonist 1S3R‐aminocyclopentone‐1, 3‐dicarboxylic acid (ACPD) on phosphoinositol hydrolysis, but only at a concentration of 10–3M, which is unlikely to have functional relevance. Clomethiazole was also without effect on ligand binding to Ca2+channels (N‐ or L‐ type), Na+channels or ATP‐sensitive K+channels. Potentiation of GABA function therefore remains the most plausible explanation for the neuroprotective activity of clomethiazole.
Effects of Lead Exposure on Licking and Yawning Behaviour in Rats
Authors: Ghazi‐Khansari Mahmoud , Rezvani Niloufar , Bani‐Assadi Shadi , Zarrindast Mohammad‐Reza
Published: March 2009

Abstract:In the present study, effects of lead exposure on licking and yawning behaviour have been studied. The dopaminergic receptor agonist, apomorphine (0.15, 0.25 and 0.5 mg/kg), induced dose‐dependent licking in rats. The maximum response was obtained with 0.5 mg/kg of the apomorphine. Lead acetate (0.05%) exposure significantly increased apomorphine‐induced licking. Yawning induced by the D2dopaminergic agonist, bromocriptine (2, 3, 4, 8 mg/kg), and the cholinergic drug, physostigmine (0.1 or 0.3 mg/kg), was significantly decreased by lead acetate (0.05%) exposure. It may be concluded that the behaviour induced by dopaminergic or cholinergic agents can be affected by lead subchronic exposure.
Interactions between Antinociception Induced by Cholecystokinin Antagonists and GABA Agonists in the Tail‐Flick Test
Authors: Zarrindast Mohammad‐Reza , Rezayat Mehdi , Ghanipoor Nahid , Parvini Shirin
Published: March 2009

Abstract:In this work, the influences of cholecystokinin receptor antagonists L‐365,260, MK‐329 and proglumide on antinociception induced by baclofen and GABA uptake inhibitor 4, 5, 6, 7–tetrahydroisoxazolo [4, 5‐c]pyridin‐3‐ol (THPO) in the tail flick test has been studied. Baclofen and THPO induced antinociception in the tail flick test. Morphine, and the CCK receptor antagonists, MK‐329, L‐365,260 and proglumide also induced antinociception. The CCK receptor antagonists potentiated antinociceptive response induced by both baclofen and THPO. It may be concluded that cholecystokinin receptor mechanism(s) may interact with antinociception induced by GABA receptor mechanism(s).
Lipid Peroxidation Induced by Adriamycin in Linolenic Acid‐Loaded Cultured Hepatocytes
Authors: Furuno Koji , Suetsugu Tatsuya , Shimomichi Kimi , Tsuruta Yasuto , Sugihara Narumi
Published: March 2009

Abstract:Addition of more than 10 μM of adriamycin to cultured rat hepatocytes loaded with α‐linolenic acid (linolenic acid‐loaded hepatocytes) caused marked lipid peroxidation as measured by an accumulation of malondialdehyde during a 9 hr incubation. After addition of 50 μM of adriamycin to linolenic acid‐loaded hepatocytes, malondialdehyde accumulation significantly increased at 3 hr, followed by cellular reduced glutathione decrease and lactate dehydrogenase leakage after 6 hr. Inhibition of adriamycin‐induced lipid peroxidation by addition of N, N′‐diphenyl‐p‐phenylenediamine or α‐tocopherol, both lipid radical scavengers, or deferoxamine, which is a Fe ion chelator, prevented both glutathione decrease and lactate dehydrogenase leakage, indicating that lipid peroxidation caused cellular damage to linolenic acid‐loaded hepatocytes exposed to adriamycin. The effect of SKF 525‐A, which is a cytochrome P450 inhibitor, on adriamycin‐induced lipid peroxidation and on 7‐ethoxycoumarin O‐deethylase activity was determined by 6 hr incubation of linolenic acid‐loaded cells. Addition of SKF 525–A suppressed adriamycin‐induced lipid peroxidation comparably with its 7‐ethoxycoumarin 0‐deethylase inhibitory activity. These results suggest that cytochrome P450 contributes to the one‐electron bioreduction of adriamycin into its semiquinone radical in rat hepatocytes.
Cytoprotection by Deprenyl and Tolcapone in a Cell Culture Model of Cerebral Ischaemia
Authors: Ekblom Jonas , Tottmar Olof , Oreland Lars
Published: March 2009

Abstract: Foetal rat brain aggregation cultures were exposed to a single episode of anoxia and hypoglycaemia for 30 min. Lactate dehydrogenase specific activity was estimated in the culture medium after ischaemia as a marker of lost cell integrity. Release of lactate dehydrogenase was most prominent during the first 24 hr period after the ischaemic damage, then it gradually declined. Immediately after ischaemic exposure, the cultures were treated with different concentrations of L‐deprenyl or tolcapone. Significantly lower amounts of lactate dehydrogenase leaked into the culture medium during the first 24 hr after the ischaemic episode in cultures treated with deprenyl or tolcapone (1–100 nM). These results suggest that deprenyl and tolcapone may reduce cell damage after ischaemia, at doses causing enzyme inhibition.