bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Parasympathetic and Sensory Transmitters on Human Epicardial Coronary Arteries and Veins
Authors: Opgaard Ole Saetrum , Edvinsson Lars
Published: March 2009

Abstract:Vasomotor effects of various agonists were tested on isolated human epicardial coronary arteries and veins at resting tension and after precontraction with U46619. Acetylcholine relaxed all arteries with intact endothelium but only some endothelium‐denuded arteries. Most veins did not relax to acetylcholine. Higher concentrations of acetylcholine induced powerful contractions of all arteries and veins. Preincubation with atropine significantly lowered the pD2values but not Emaxvalues for contractile responses to acetylcholine in arteries and veins (pA2value for atropine 9.1 arteries and 9.6 veins). Vasoactive intestinal peptide, human α‐calcitonin gene‐related peptide and substance P potently relaxed all arteries with intact endothelium and all veins. Removal of the arterial endothelium abolished relaxation to substance P in most arteries whereas responses to vasoactive intestinal peptide were unaffected, and for a‐calcitonin gene‐related peptide the pD2value but not the Emaxvalue was significantly lowered. In both arteries and veins, the antagonists α‐calcitonin gene‐related peptide (8‐37) and spantide lowered significantly the potency for a‐calcitonin gene‐related peptide and substance P, respectively, without significant changes in Emaxvalues (pA2value for α‐calcitonin gene‐related peptide (8‐37) 7.9 arteries and 7.9 veins, for spantide 7.6 arteries and 8.1 veins).
Cytotoxic Action of tri‐n‐Butyltin on Dissociated Rat Cerebellar Neurones: A Flow‐Cytometric Study
Authors: Ueha Toshiko , Oyama Yasuo , Tomiyoshi Fukiyo
Published: March 2009

Abstract:The effects of tri‐n‐butyltin on cell viability and intracellular Ca2+concentration ([CA2+]i) were examined by a flow cytometer in rat cerebellar neurones to reveal the contribution of tri‐n‐butyltin‐induced increased in the [Ca2+]i to its cytotoxicity. Tri‐n‐Butyltin decreased the cell viability in association with increased [Ca2+]i at concentrations of 0.3 μM or more. Decrease or increase of the extracellular Ca2+concentration ([Ca2+]o) respectively decreased or increased the cell viability. However, cell viability in the presence of ionomycin which increased [Ca2+]i more significantly than tri‐n‐butyltin was higher than that in the presence of tri‐n‐butyltin. Tri‐n‐butyltin also decreased cell viability under nominally [Ca2+]o‐free conditions although the [Ca2+]i increase by tri‐n‐butyltin was still lower than the control [Ca‐+]i under normal [Ca2+]o (2 mM). Therefore, it is unlikely that neuronal death induced by tri‐n‐butyltin is entirely dependent on the tri‐n‐butyltin‐induced increase in [Ca2+]i.
Enhancement of Brain Noradrenaline and Dopamine Turnover by Thyrotropin‐Releasing Hormone and its Analogue NS‐3 in Mice and Rats
Authors: Itoh Yoshinori , Yamazaki Akira , Ukai Yojiro , Yoshikuni Yoshiaki , Kimura Kiyoshi
Published: March 2009

Abstract:The effects of intravenous injections of thyrotropin‐releasing hormone and its analog NS‐3 (montirelin hydrate, CG3703) on the dynamics of brain monoamines were examined in mice and rats. In mice, both NS‐3 (0.1‐1 mg/kg) and thyrotropin‐releasing hormone (10 and 30 mg/kg) increased the concentrations of 4‐hydroxy‐3‐methoxyphenylglycol, 3,4‐dihydroxyphenylacetic acid and homovanillic acid. The turnover rates, estimated either by depletion of catecholamines after treatment with α‐methyl‐p‐tyrosine or by probenecid‐induced accumulation of homovanillic acid, were enhanced by these peptides. In contrast, none of the compounds had any influence on the serotonin turnover. In rats, both NS‐3 and thyrotropin‐releasing hormone produced a regionally specific increase in the concentrations of the catecholamine metabolites. A microdialysis study demonstrated that NS‐3 significantly increased the release of dopamine in the nucleus accumbens as well as the striatum of conscious rats, while thyrotropin‐releasing hormone caused a weak but significant enhancement of dopamine release only in the nucleus accumbens. These findings indicate that NS‐3 was far more potent than thyrotropin‐releasing hormone in facilitating the turnover of catecholamines without affecting serotonin turnover in the mouse and rat brain.
8‐Bromo‐cAMP and 8‐CPT‐cAMP Increase the Density of β‐Adrenoceptors in Hepatocytes by a Mechanism Not Mimicking the Effect of cAMP
Authors: Sandnes Dagny , Jacobsen Frede W. , Refsnes Magne , Christoffersen Thoralf
Published: March 2009

Abstract:Addition of 8‐bromo‐adenosine 3′,5′‐cyclic monophosphate (8‐bromo‐cAMP) or 8‐(4‐chlorophenylthio)‐adenosine 3′,5′‐cyclic monophosphate (8‐CPT‐cAMP) to hepatocytes at the time of plating enhanced the acquisition of β‐adrenoceptors that occurs spontaneously upon culturing as primary monolayers. This effect was partially suppressed by the phosphodiesterase inhibitor isobutyl methylxanthine, and was mimicked by 8‐bromo‐AMP, 8‐bromo‐adenosine, and the adenosine kinase inhibitor 5′‐amino‐5′‐deoxyadenosine. Agents that elevated the intracellular level of cAMP, such as glucagon and forskolin, and Sp‐8‐bromo‐adenosine 3′,5′‐monophosphorothioate (Sp‐8‐bromo‐cAMPS), a cAMP analogue that is resistant towards metabolic breakdown, did not significantly enhance β‐adrenoceptor expression when used alone, but glucagon enhanced the effect of 8‐bromo‐adenosine. 8‐Bromo‐cAMP and 8‐bromo‐adenosine decreased cellular ATP‐levels. These observations suggest that the enhanced β‐adrenoceptor acquisition was mediated mainly through the action of metabolites of 8‐bromo‐cAMP and 8‐CPT‐cAMP, although there may be a cAMP‐mediated component in the effect. Several mechanisms, including depletion of ATP, are probably involved, and might affect β‐adrenoceptor degradation.
Disposition and Analgesic Effects of Systemic Morphine, Morphine‐6‐glucuronide and Normorphine in Rat
Authors: Hasselström J. , Svensson J. O. , Säwe J. , Wiesenfeld‐Hallin Z. , Yue Q‐Y. , Xu X‐J.
Published: March 2009

Abstract:Morphine, morphine‐6‐glucuronide and normorphine were administered to male Sprague‐Dawley‐rats. Analgesic effect was estimated with the hot plate and spinal nociceptive reflex depression. After intraperitoneal administration the molar potency ratio of morphine‐6‐glucuronide/morphine was 1.7 estimated by the paw lick latency on the hot plate utilizing a linked pharmacokinetic‐pharmacodynamic model. The potency ratio of morphine‐6‐glucuronide/morphine utilizing the spinal nociceptive reflex depression after intravenous administration was estimated to be within the earlier reported range of 1‐4 after systemic administration of the drugs. In contrast to what is seen in man virtually no morphine‐6‐glucuronide was formed in Sprague‐Dawley rats after administration of morphine, much lower levels of morphine‐3‐glucuronide were also seen. The molar AUC ratio of morphine‐3‐glucuronide/morphine was 1.8±0.5 and the corresponding ratio for normorphine/morphine was 0.2±0.06. After intraperitoneal administration of morphine, morphine‐6‐glucuronide and normorphine mean systemic clearance values of 413±95, 50±11 and 187±54 ml·±min·kg‐1respectively were observed. Vareawas 9.0±2.1, 0.8±0.2 and 4.9±1.4 L±kg‐1respectively. The slow absorption of morphine‐6‐glucuronide was illustrated by the mean Tmax‐value of 16 min. as compared with 9 min. for morphine and 10 min. for normorphine. It was possible to fit pharmacokinetic and pharmacodynamic data of behavioural analgesic effect of both morphine and morphine‐6‐glucuronide to a parametric model linking the sigmoid Emaxmodel to standard pharmacokinetic equations.
Alteration in some Membrane Properties in Rat Brain Following Exposure to Manganese
Authors: Kumar Raj , Srirastava Sanjay , Agrawal Ashok K. , Seth Prahlad K.
Published: March 2009

Abstract: Earlier clinical and experimental studies have suggested that manganese‐induced central nervous system dysfunction involves alterations in levels of dopamine, DA receptors, autoxidation of dopamine and generation of free radicals (Seth & Chandra 1988). In order to investigate whether exposure to manganese leads to alteration in membrane functions, we studied the levels of malondialdehyde formation, phospholipid and cholesterol contents and membrane fluidity in the brain regions of rats exposed to manganese for 30 days.
Influence of Biochemical Parameters of Liver Function on Vancomycin Pharmacokinetics
Authors: Martí R. , Rosell M. , Pou L. , García L. , Pascual C.
Published: March 2009

Abstract: The influence of biochemical parameters of hepatic function on vancomycin pharmacokinetics was retrospectively evaluated in 76 adult patients (age 18 to 81 years), from biochemistry data gathered during routine therapeutic drug monitoring. All subjects had normal serum creatinine levels. Vancomycin concentrations were determined by fluorescence polarization immunoassay in 101 paired serum samples. All data for vancomycin concentration versus time were fitted to a one‐compartment model using the bayesian approach. Bilirubin, transaminases (n = 101), γ‐glutamyl transferase (n=97), alkaline phosphatase (n=95), albumin (n=92) and lactate dehydrogenase (n=42) were determined. No strong correlation was seen between any of the pharmacokinetic and biochemistry parameters studied. In patients with hyperbilirubinaemia, the mean Vss and t1/2 were increased (Vss: 0.75±0.31 versus 0.92±0.421 .kg‐1, p=0.020; t1/2 5.93±3.30 versus 7.48±4.44 hr, p=0.049). When liver function was evaluated according to hepatic profile (normal, mildly altered and severely altered), no significant differences were observed in vancomycin pharmacokinetics among the groups. In conclusion, vancomycin pharmacokinetics are only weakly influenced by the biochemistry parameters of liver function.
Elimination of Recently Absorbed Methyl Mercury Depends on Age and Gender
Authors: Nielsen Jesper B. , Andersen Ole
Published: March 2009

Abstract: The toxicokinetics of some toxic metals have been demonstrated to depend on the age of the exposed individuals. Most studies focused solely upon age‐dependent differences in degree of absorption. The present study aimed at investigating possible age‐dependent differences in elimination of CH3HgCl using 203Hg and repeated whole‐body counting of live mice to quantitate the whole‐body retention. With increasing age at the time of exposure to a single oral dose of CH3HgCl, the rate of elimination more than doubled in male mice. As intestinal absorption of CH3HgCl is almost complete, the findings must pertain either to an age‐related increased excretion capacity or an age‐dependent change in the excretion mechanism. To study whether saturation of the excretion mechanism could explain this observation, groups at different age were supplemented with non‐labeled CH3HgCl in the drinking water during a two weeks observation period after administration of a single dose of CH3203HgCl. Supplementation did not influence the rate of elimination of CH3HgCl in mature males. Accordingly, the mechanism causing the observed age‐dependent change in elimination rate is not a matter of saturation but an age‐dependent development of a more efficient mechanism for CH3HgCl elimination. Further, as elimination of mercury absorbed during a prolonged period of exposure through drinking water was not influenced by age, the critical step for the age‐dependent mechanism for elimination of CH3HgCl seems to be the initial absorption and distributional phase after exposure and most likely involves the hepatic handling of methyl mercury.
Distribution of Glutathione S‐Transferase Isoforms in Rat Liver after Induction by β‐Naphthoflavone or 3‐Methylcholanthrene
Authors: Sippel H. , Lindros K. O. , Oinonen T.
Published: March 2009

Abstract: Regional differences in vulnerability to xenobiotic liver damage may relate to the distribution of the detoxication capacity of the glutathione S‐transferases (GST). HPLC analysis of cell lysates obtained by digitonin infusion from either the periportal or the perivenous region revealed that the content of all the GST subunits investigated (1, 2, 3, 4 and 8) was higher in the perivenous region. The strongest perivenous dominance was observed for subunit 1 (Ya) and the α class appeared to be more zonated that the μ class. A similar perivenous dominance was observed by analysis of GST activity with either 1‐chloro‐2,4‐dinitrobenzene (CDNB), 1,2‐dichloronitrobenzene (DCNB) or trans‐4‐phenyl‐3‐buten‐2‐one (PBO) as substrate. In contrast, with cumene hydroperoxide (CuOOH) or tert‐butyl hydroperoxide (tBOOH) as substarate a reciprocal twofold periportal dominance was observed. Induction by pretreatment with β‐naphthoflavone reduced or abolished the perivenous dominance of the α subunits 1, 2 and 8. In contrast, after pretreatment with 3‐methylcholan‐threne, only the acinar gradient of subunits 2 (Yc) was abolished, while the strong perivenous gradient subunit 1 (Ya) was maintained and that of subunit 8 (Yk) increased. CDNB based assays demonstrated that β‐naphtoflavone treatment reduced (from 2.1 to 1.4) while 3‐methyl cholanthrene enhanced (to 2.6) the perivenous/periportal GST activity ratio. Assays based on CuOOH or tBOOH indicated that neither the Se‐dependent nor the Se‐independent glutathione peroxidase activity nor its acinar distribution was affected by the inducers. These results demonstrated that although the expression of all investigated members of the alpha and mu classes is higher in the perivenous region, there are marked isozyme differences, the acinar gradient being particularly prominent for subunit 1 (Ya). The distinct difference in the acinar induction pattern of GST Ya between β‐naphthoflavone and 3‐methylcholanthrene resembles that reported for cytochrome P450 (CYP1A1 and CYP1A2), also members of the aryl hydrocarbon (Ah) receptor genes, suggesting common regionally acting regulatory elements in the expression of these genes in the liver.
Lithium and Valproate Combined Administration: Acute Behavioural Effects and Drug Plasma Levels
Authors: Vargas Carmen , Tannhauser Mario , Tannhauser Semiramis L. , Barros Helena M. T.
Published: March 2009

Abstract: Drug plasma concentrations and behavioural effects of acute combined administration of lithium and valproic acid were studied in normonatraemic and hyponatraemic rats. Hyponatraemia was induced two hours before drug administration and behavioural observations lasted for two additional hours. Blood was collected by the end of the behavioural observation. The higher doses of valproic acid (360 mg/kg) or lithium (2 mEq/kg) induced more head‐shakes and higher plasma concentration than 180 mg/kg of valproic acid or lithium 1 mEq/kg, respectively. Valproic acid and lithium administered separately induced more head shakes and higher drug plasma levels in hyponatraemic rats than in normonatraemic animals. Combined administration of valproic acid (180 mg/kg) and lithium (2 mEq/kg) produced a supra‐aditive effect in head‐shakes. The drug interaction between lithium and valproic acid induced a decrease in valproic acid plasma level and an increase in lithium plasma levels.
Uptake of 7,12‐Dimethylbenz(a)anthracene and Benzo(a)pyrene in Melanin‐Containing Tissues
Authors: Roberto Amilcar , Larsson Bengt S. , Tjälve Hans
Published: March 2009

Abstract:It is widely accepted that UV exposure is the main etiological factor for malignant melanoma. Epidemiologic studies, however, have indicated that also chemical carcinogens may be a risk factor for the disease. Polycyclic aromatic hydrocarbons such as 7,12‐dimethylbenz(a)anthracene and benzo(a)pyrene represent an important class of carcinogenic chemicals. It is known that 7,12‐dimethylbenz(a)anthracene can induce melanotic tumours in various animal species, and human melanocytes in culture have been found to be capable of metabolizing benzo(a)pyrene to its proximate carcinogen benzo(a)pyrene‐7,8‐diol. In the present study the disposition of14C‐ and3H‐7,12‐dimethylbenz(a)anthracene and14C‐benzo(a)pyrene was studied in pigmented and albino mice and Syrian golden hamsters by whole‐body autoradiography. The results showed pronounced retention of label in the melanin‐containing structures of the eyes and the hair follicles in the pigmented animals. The labelling of the corresponding structures in the albino animals was low. Additional experiments showed that 7,12‐dimethylbenz(a)anthracene and benzo(a)pyrene as well as some of their metabolites are bound to melaninin vitro.The specific localization of the polycyclic aromatic hydrocarbons in pigmented tissues due to melanin affinity, combined with bioactivating capacity of melanocytes, suggest that these substances may play a role in the induction of malignant melanoma.
The mu1and mu2opioid receptor binding of ketobemidone, norketobemidone and 3‐dimethylamino‐1,1‐diphenylbutene
Authors: Kristensen Kim , Christensen Chr. Broen , Christrup Lona Louring , Nielsen Lene Colberg
Published: March 2009

Abstract:Ketobemidone is a mu receptor agonist, available in Scandinavia in a combined preparation (Ketogan$$), which contains ketobemidone and the spasmolytical agent 3‐dimethylamino‐1, 1‐diphenylbutene (A29) in a one to five ratio. A29 is chemically related to methadone and experiments in rats have shown that A29 potentiates the analgesic effect of ketobemidone (Petersen 1951). We have recently shown that ketobemidone has lower binding affinity for the total mu receptor than morphine. At $$‐binding sites the two opioids have equal affinity, whereas ketobemidone has much lower affinity than morphine to the $$ receptor (Christensen 1993). The existence of two subtypes of mu receptors has been suggested by Pasternak and co‐workers: a high affinity, mu1receptor subtype that appears to mediate supraspinal analgesia and a low affinity, mu2subtype that appears to mediate spinal analgesia, respiratory depression and inhibition of gastrointestinal motility (Clarket al.1988; Paulet al.1989).
Teratogenicity of a Single Oral Dose of Retinyl Palmitate in the Rat, and the Role of Dietary Vitamin A Status
Authors: Piersma A. H. , Bode W. , Verhoef A. , Olling M.
Published: March 2009

Abstract: Vitamin A, known for its teratogenic properties, may be present in high concentrations in consumption liver. It is as yet unclear whether congenital malformations can result from a single liver meal. In our first experiment, the teratogenicity of a single dose of retinyl palmitate was tested in the rat. Pregnant rats were treated at day 10 of gestation by gavage with 100, 300 or 1000 mg/kg body weight retinyl palmitate on a dietary background level of 5 mg/kg feed. At gestation day 11 the number of embryos with an open cranial neural tube had increased with the dose. At gestation day 21, the high dose group showed an increase in late resorptions, whereas both the high and the medium dose groups had a high incidence of foetuses with malformations typical of retinoid embryopathy. The data suggest that delayed neural tube closure had occurred in a large proportion of the embryos. In a second experiment, the high oral dose was applied on gestation day 10 in pregnant rats receiving retinyl palmitate at 1.5, 5, 15, or 50 mg/kg feed for 6 weeks. Delayed neural tube closure, post‐implantation loss and the nature and incidence of malformations were similar between diet groups, as well as being reminiscent of the high dose group in the first experiment. Thus the dietary status of the animals did not seem to influence the teratogenic potential of a single high dose of retinyl palmitate.
Bioavailability of Recombinant Human Growth Hormone in Different Concentrations and Formulations
Authors: Vahl Nina , Jensen Simone B. , Rasmussen Michael H. , Susgaard Søren , Jørgensen Jens O. L. , Christiansen Jens S. , Rasmussen Ulla F. , Hilsted Jannik
Published: March 2009

Abstract: Whether the bioavailability of growth hormone depends on the concentration or formulation of the preparation was evaluated in 18 growth hormone‐deficient patients. The design was a single‐blinded, randomized cross‐over study, where the patients were given a single, fixed dose subcutaneous injection of growth homrone (3 IU/m2) of 3 different preparations: (1) 4 IU/ml in a bicarbonate buffer dissolved in 0.9% benzyl alcohol (∼1.37 mg/ml), (2) 5.9 IU/ml in a phosphate buffer dissolved in 1.5% benzyl alcohol (∼2 mg/ml) and (3) 11.7 IU/ml in a phosphate buffer dissolved in 1.5% benzyl alcohol (∼4 mg/ml). Conventional growth hormone‐therapy was withdrawn 2 days before each study period. Blood samples were drawn over a 24‐hr period and assessed for growth hormone, serum insulin‐like growth factor I (IGF‐I), insulin and glucose. The geometric mean values (∼geometric S.D.) of the relative absorption fractions were F5.9 IU/4 IU= AUC5.9 IU/AUC4 IU=(∼1.139) (P=0.66), F11.7 IU/AUC4 IU=AUC11.7 IU/AUC4 IU (1.14±1.21) (P=0.009) and F11.7 IU/5.9 IU=AUC11.7 IU/AUC5.9 IU=1.12 (∼1.17) (P=0.005), respectively. The 90% confidence intervals were contained within the limits of 0.80‐1.25 accepted for bioequivalence. Geometric mean values (∼geometric S.D.) of the relative observed maximum concentration, Cmax was for Cmax 5.9 IU/Cmax 4 IU = 1.04 (∼1.19) (P=0.32), Cmax 11.7 IU/Cmax 4 IU=1.24 (∼1.21) (P=0.0002) and Cmax 11.7 IU/Cmax 5.9 IU=1.19 (∼1.29) (P=0.012). The median and the range values for the observed time to reach Cmax was tmax 5.9 IU/tmax 4 IU=0.63 (0.04‐1.00), tmax 11.7 IU/tmax 4 IU=0.59 (0.06‐1.0) and tmax 11.7 IU/tmax 5.9 IU=0.90 (0.51‐18.00). There were no significant differences in IGF‐I, glucose and insulin profiles. Based on the upper limits of the 90% confidence intervals for relative AUC's the conclusion is that the three different preparations were bioequivalent.
Effect of Perinatal Lead Exposure on Rat Behaviour in Open‐Field and Two‐Wky Avoidance Tasks
Authors: Rodrigues Ana Lúcia S. , Rocha João Batista T. , Mello Carlos F. , Souza Diogo O.
Published: March 2009

Abstract: In view of conflicting results in literature concerning lead exposure associated with behavioural alterations, this study investigated behaviour in the open‐field and shuttle avoidance, for as well as tissue lead burdens of pre‐ and post‐natally lead‐exposed rats. Rats were exposed to the metal from conception to weaning by giving the dams 0.5, 2.0 or 4.0 mM lead acetate in drinking water. This regimen did not affect body weight gain of dams or offspring development and had no effect on cerebral weights nor on haematological parameters of 23‐day‐old rats. In 1‐day‐old rats, lead accumulated in the blood but not in the brain, whereas both in 23‐day‐old rats and in dams lead accumulated in blood, kidney and cerebral cortex. In the open‐field, lead‐exposed groups showed higher locomotor activity in the test session as compared to controls and did not show any decrease in rearing responses in the test, indicating less habituation. Lead‐treated rats subjected to a shuttle avoidance task showed no significant increase in avoidance responses between sessions as compared to control, indicating less retention. Moreover, only the control group presented a significant reduction of the footshock escape latency along testing session, suggesting a lead effect on footshock escape acquisition. In the shuttle box, intertrial crossing responses were not affected by lead treatment. The behavioural alterations occurred in animals with blood lead levels in the range 11‐50.6 μg/dl.
Effect of Concomitant Administration of Clodronate and Estramustine Phosphate on their Bioavaibility in Patients with Metastasized Prostate Cancer
Authors: Kylmälä Timo , Castrén‐Kortekangas Päivi , Seppänen Jaakko , Ylitalo Pauli , Tammela Teuvo L. J.
Published: March 2009

Abstract: Estramustine phosphate is generally used as a second‐line treatment in patients with advanced prostate cancer. The bone metastases due to the cancer are often treated simultaneously with clodronate in order to relieve the bone pain. Therefore, the interaction of clodronate (800 mg orally four times daily) and estramustine phosphate (280 mg orally twice daily) on their bioavailability was studied in twelve patients with prostate carcinoma and bone metastases. The drugs were first given separately, each to six patients, for five days, and then concomitantly for the same period. The bioavailabilities of the drugs were calculated on the last day of each treatment period. When clodronate was given alone, its concentrations in serum and AUC for one dose interval (6 hr) did not differ from those obtained with the drug given concomitantly with estramustine phosphate, nor did the combination of estramustine phosphate change the excretion of clodronate in urine. The serum concentrations of estramustine phosphate were elevated by about 80% when the drug was given together with clodronate. The AUC for one dose interval (12 hr) was also significantly higher for estramustine phosphate with clodronate than without clodronate. The urinary excretion of estrone, a major metabolite of estramustine phosphate, was also significantly higher after the admission with clodronate. The results suggest that clodronate increases the oral bioavailability of estramustine phosphate.
Characterisation of the Melanocortin 4 Receptor by Radioligand Binding
Authors: Schiöth H. B. , Muceniece R. , Wikberg J. E. S.
Published: March 2009

Abstract: The DNA encoding the human melanocortin 4 receptor was expressed in COS (CV‐1 origin, SV 40) cells and its radioligand binding properties was tested by using the [125I][Nle4, D‐Phe7]α‐melanocyte stimulating hormone (MSH). The radioligand was found to bind to a single saturable site with a Kd of 3.84±0.57 nmol/1 in the MC4 receptor expressing cells. The order of potency of a number of substance competing for the [125I][Nle4, D‐Phe7]α‐MSH binding was the following; [Nle4, D‐Phe7]α‐MSH>[Nle4]‐α‐MSH>β‐MSH>desacetyl‐α‐MSH>α‐MSH>ACTH (1‐39)>ACTH (4‐10)>γ1‐MSH>γ2‐MSH. This order of potency is unique for the melanocortin 4 receptor when compared to our previously published data for the other melanocortin receptor subtypes. Most notably the melanocortin 4 receptor shows highest affinity for β‐MSH, among the endogenous MSH‐peptides. Furthermore the melanocortin 4 receptor shows very low affinity for the γ‐MSH peptides. This distinguishes the melanocortin 4 receptor from the melanocortin 3 receptor, which is the other major central nervous system melanocortin‐receptor, as melanocortin 3 receptor shows high affinity for γ‐MSH. Our finding might indicate a specific role for β‐MSH for the melanocortin 4 receptor.
The Effects of Sodium Lauryl Sulfate on the Phrenic Nerve Diaphragm Preparation from the Rat
Authors: Herlofson Bente Brokstad , Brodin Pål , Røed Asbjørn
Published: March 2009

Abstract:The time period to 50% inhibition of the twitches and compound action potential of the rat phrenic nerve‐diaphragm preparation with sodium lauryl sulfate (2.5X10‐4‐5.0X10‐3M) was recorded. The twitch contractions during indirect stimulation, the contraction during direct stimulation, and the compound action potential of the isolated phrenic nerve, were inhibited in that order. Depolarization due to high action potential activity induced by tetanic stimulation, veratridine, low Ca2+‐ or high K+‐solutions, all enhanced the inhibitory effect of sodium lauryl sulfate (5.0X10‐4M) during indirect stimulation. Hyperpolarization in K+‐free solution and membrane stabilization by lidocaine antagonized the inhibitory effect of sodium lauryl sulfate. Accordingly, it probably induced inhibition by depolarization. The depolarization may decrease the influx of Ca2+and the reuptake of choline+, as suggested by an observed synergism with tetraethylammonium Cl and hemicholinium‐3 Br, which antagonize the reuptake of choline+. On the opposite, 3,4‐diaminopyridine, which increases the influx of Ca2+, antagonized the sodium lauryl sulfate‐induced inhibition, and induced a biphasic contracture. The first phase was probably caused by a depolarization, and the second phase by release of Ca2+from the sarcoplasmic reticulum. The potentiation of the second phase by dantrolene and in low Ca2+solution, was attributed to sodium lauryl sulfate‐induced desensitization.
Four Weeks’Inhalation Exposure of Rats to p‐Cymene Affects Regional and Synaptosomal Neurochemistry
Authors: Lam Henrik Rye , Ladefoged Ole , Østergaard Grete , Lund Søren Peter , Simonsen Leif
Published: March 2009

Abstract: Long‐lasting effects of inhalation exposure to p‐cymene (p‐isopropyl‐toluene; CAS No. 99‐87‐6) on regional and subcellular brain neurochemistry were studied. Male Long‐Evans rats were exposed to 0, 50, or 250 p.p.m. p‐cymene 6 hr/day, 5 days/week for four weeks followed by an exposure‐free period of 8 weeks. Synaptosomes were isolated from whole brain minus cerebellum and used as an ex situ model for in situ conditions at the level of the presynaptic nerve terminal. There was no persistent effect on wet weight (regional) or regional noradrenaline (NA), dopamine (DA), or 5‐hydroxytryptamine (5‐HT) concentrations owing to exposure. Yield of synaptosomal protein was statistically significantly reduced in an exposure concentration‐related manner (Control: 16.6±3.1; 50 p.p.m.: 9.2±2.1; 250 p.p.m.: 8.6±1.7 mg protein/g tissue, mean± 1 S.D.). Synaptosomal NA and DA concentrations and acethycholinesterase, butyrylcholinesterase, and lactate dehydrogenase activities were statistically significantly increased when expressed relative to synaptosomal protein. It is hypothesized that a reduced density and number of synapses in situ are functionally compensated for by increased NA and DA release from noradrenergic and dopaminergic presynaptic nerve terminals. The applicability of the synaptosome as an ex situ neurochemical research model for the presynaptic CNS nerve terminal in situ for the study of solvent neurotoxicity in rats was further supported.
The Prophylactic Effects of U75412E Pretreatment in a Smoke‐Induced Lung Injury Rabbit Model
Authors: Wang Shengjun , Lantz R. Clark , Chen Guan Jie , Breceda Veronica , Rider Evelyn , Hays Allison M. , Parliman Grace , Tollinger Brian J. , Robledo Raymond F. , Kunke Kathleen , Tinajero Julieta , Witten Mark L.
Published: March 2009

Abstract: The effects of the lazaroid analogue U75412E (21‐[4‐(3‐ethylamino‐2‐pyridinyl)‐1‐piperazinyl]‐16α‐methylpregna‐1,4,9]‐(11)‐triene‐3,20‐dione) were examined in an acute lung injury rabbit model. Standard doses of 0, 8 and 16 mM U75412E were aerosolized and ventilated into the lungs for 3 min. via an endotracheal tube. A 60 tidal volume dose of diesel fuel‐polycarbonate plastic smoke was then instilled, followed by mechanical ventilation for one hour. Pretreatment with 16 mM U75412E significantly increased blood PaO2 and pH values, and decreased blood PaCO2 as compared to smoke only exposures. It also significantly decreased the total cell counts and granulocytes in bronchoalveolar lavage fluid, and the ability of pulmonary alveolar macrophages to produce tumour necrosis factor‐α in vitro after cell isolation and culture. Histopathology indicated that 16 mM U75412E pretreatment attenuated increases in wet lung/body weight ratios, inflammatory focus, and interstitial oedema associated with smoke insult. In summary, U75412E pretreatment may possess the potential to improve acute smoke‐induced lung injury, in part, through modulation of tumour necrosis factor‐α production from pulmonary alveolar macrophages.
Effect of Colchicine and Trimethylcolchicinic Acid on CCl4‐Induced Cirrhosis in the Rat
Authors: Cedillo Aranzazú , Mourelle Marisabel , Muriel Pablo
Published: March 2009

Abstract: Colchicine is one of the most promising drugs for the treatment of cirrhosis. However, due to its toxicity, other drugs are being evaluated and colchicine‐like molecules may be good alternatives. The aim of this work was to compare the beneficial effects of colchicine and trimethylcolchicinic acid (a colchicinoid less toxic than colchicine) on CCl4‐cirrhosis. The drugs were administered either through CCl4 administration (8 weeks) or after CCl4 intoxication for 4 weeks at a dose of 10 μg/rat/day, orally. Liver plasma membranes were isolated for high affinity Ca2+‐ATPase, γ‐glutamyl transpeptidase and alkaline phosphatase activities. The activities of γ‐glutamyl transpeptidase and alkaline phosphatase were also measured in serum. Liver glycogen content and a marker for lipid peroxidation were determined in liver samples. We found that both compounds preserved and significantly reversed high affinity Ca2+‐ATPase, γ‐glutamyl transpeptidase and alkaline phosphatase plasma membrane and serum enzyme activities as well as the hepatic glycogen content.
Vitamin E Decreases Urine Lipid Peroxidation Products in Young Healthy Human Volunteers under Normal Conditions
Authors: Cadenas Susana , Rojas Caridad , Méndez Julia , Herrero Asunción , Barja Gustavo
Published: March 2009

Abstract: An experimental study on the effects of supplementation with antioxidant vitamins on urine lipid peroxidation products was performed in 21 young healthy men. The subjects ingested placebo, 1 g of vitamin C, or 100 mg of vitamin E per day just after the midday meal during 30 days. Urine samples were obtained 0, 15 and 30 days after the beginning of the study. These samples were analyzed by spectrophotometry or fluorometry after reaction with thiobarbituric acid. Prescan fluorometric studies of the thiobarbituric acid reactive substances in both malondialdehyde standards and urine samples indicated 503 nm and 548 nm as optimum excitation and emission wavelengths. The fluorescence measurements proved to be superior both in terms of selectivity and capacity of detection of antioxidant effects in relation to spectrophotometry. Identical emission peaks were obtained with malondialdehyde standards and urine samples, showing the specificity of the fluorometric method. When measured by fluorometry, the urine of the subjects supplemented with vitamin E showed significantly and progressively smaller lipid peroxidation products as the time of supplementation increased, reaching a 27% decrease at the end of the longitudinal trial. The results indicate the usefulness of the fluorescent measurement of urine thiobarbituric acid reactive substances to easily and rapidly detect variations in whole body oxidative stress in humans. They also show the capacity of safe vitamin E dietary doses to decrease endogenous oxidative stress in healthy humans routinely performing their normal activities.
Effect of Dose, Sex and Age on the Drug Disposition of Incadronate, a New Bisphosphonate, in Rat Bone
Authors: Usui Takashi , Watanabe Takashi , Higuchi Saburo
Published: March 2009

Abstract:We investigated the effects of dose, sex and age on the uptake and elimination of incadronate, a new biosphos‐phonate, in rat bone after intravenous administration. Following administration of 0.03‐3 mg/kg to young male rats (age 7 weeks), intact drug concentration in humerus at 24 hr after administration (C24 hr) increased in a dose‐dependent manner, indicating the linear uptake of the drug into bone. The estimated bone uptake clearance of 0.13 ml/min./g bone is comparable to the estimated plasma flow rate in bone, suggesting that uptake into bone is plasma flow‐limited. Concentration from 24 hr after administration had declined bi‐exponentially. Although t1/2β(350‐444 days) was little altered among doses, t1/2αwas prolonged with increasing dose from 13.4 to 16.2 days. This effect seemed to be due to inhibition of bone resorption at higher doses resulting in the suppression of drug release from bone. No sex difference was seen on C24 hrin young rats, while the value in senescent (age 12 months) rats was 24% greater in females than in males. When comparing between ages it is seen that C24 hrvalues in senescent rats decreased to 50‐66% of those in young rats. As for elimination from bone, t1/2βvalues in senescent rats were shortened to 76‐79% of those in young rats. In contrast, little difference in t1/2αwas observed between ages or in either t1/2αand t1/2βbetween sexes.
The Enhancing Effect of Tumour Necrosis Factor‐α on Oxidative Stress in Endotoxemia
Authors: Sakaguchi Shuhei , Furusawa Shinobu , Yokota Katushi , Sasaki Ken‐ichi , Takayanagi Motoaki , Takayanagi Yoshio
Published: March 2009

Abstract:The enhancing effect of tumour necrosis factor‐α (TNF‐α) on oxidative stress with or without a sublethal dose of endotoxin was examined. The mortality of mice treated with recombinant human TNF‐α (1X104units/mouse, intravenously) and endotoxin (0.01‐1 mg/kg, intraperitoneally) was dependent on the dose of endotoxin. The liver lipid peroxide level, superoxide anion generation and serum lactate dehydrogenase activity, especially serum lactate dehydrogenase‐5 isozyme leakage, in mice 2‐4 hr after administration of recombinant human TNF to endotoxin‐pretreated mice (0.5 mg/kg, intraperitoneally) were markedly higher than in those without endotoxin, whereas the administration of recombinant human TNF significantly decreased the non‐protein sulfhydryl level, superoxide dismutase and glutathione peroxide activities in the liver of endotoxin‐injected mice compared with those in mice treated with recombinant human TNF or endotoxin alone. Furthermore, findings clearly demonstrated that J774A.1 cells stimulated with recombinant human TNF (1X104units/ml) can effectively produce nitric oxide in the presence of endotoxin, and the production was dependent on the dose of endotoxin (0.01‐10 μg/ml). The level of lipid peroxide in mice 4 hr after administration of recombinant human TNF and lead acetate (50 mg/kg, intravenously) was markedly higher than that in the mice treated with recombinant human TNF alone. By contrast, injection of polymyxin‐B (20 mg/kg, intraperitoneally, an anti‐endotoxin drug) markedly decreased the lipid peroxide level in the liver of the mice treated with recombinant human TNF and lead acetate. These findings suggest that the oxidative stress caused by TNF occurs as a enhancing effect of endotoxion or by bacterial translocation from the intestinal gut under reduction of reticuloendothelial system function in various disease states, and that the effect of TNF may cause a marked increase of toxicity of oxidative stress by endotoxin.
Effects of the Neuropeptide Y (NPY)‐Receptor Antagonist BIBP3226 on Vascular NPY‐Receptors with Different Ligand Requirements
Authors: Grundemar Lars , Ekelund Mats
Published: March 2009

Abstract:The aim was to examine effects of a newly developed neuropeptide Y (NPY)‐receptor antagonist, BIBP3226 and to characterize NPY‐receptors in the isolated guinea pig caval vein and human subcutaneous artery, respectively. BIBP3226 ≤1μM did not affect the basal tension. Pretreatment with increasing concentrations of BIBP3226 (10 nM ‐ 1 μM) resulted in a progressive rightward shift of the concentration‐response curve to the Y1‐receptor selective agonist [Pro34]NPY in the guinea pig caval vein. Regression analysis of the Schild plot gave a pA2‐value of 7.58 (7.20‐8.33, 95% confidence interval), slope of regression line 0.96 (0.52‐1.39, 95% confidence interval) and a correlation coefficient of 0.78. NPY and the C‐terminal NPY 2‐36 evoked equipotent concentration‐dependent contractions, both of which were sensitive to BIBP3226. Although less potent than NPY 2‐36, also the contraction induced by NPY 5‐36 was antagonized by BIBP3226. In the human subcutaneous artery [Pro34]NPY but not NPY 2‐36 (≤0.3μM) evoked a concentration‐dependent contraction. Pretreatment with BIBP3226 (0.1 μM) resulted in a rightward shift of the concentration‐response curve to [Pro34]NPY (from 7.38±0.10 to 6.95±0.16 (P<0.05, n=6). The present study has shown that the Y1‐receptor‐selective antagonist BIBP3226 potently antagonizes vascular NPY‐receptors with different ligand requirements in the guinea pig caval vein and human subcutaneous artery, respectively. It appears that the guinea pig Y1‐receptor is much less stringent in its demand on the N‐terminal part of NPY than that of human Y1‐receptors.
The Effect of Activated Charcoal on the Absorption of Fluoxetine, with Special Reference to Delayed Charcoal Administration
Authors: Laine Kari , Kivistö Kari T. , Pelttari Sirpa , Neuvonen Pertti J.
Published: March 2009

Abstract: The effect of activated charcoal on fluoxetine (40 mg) absorption, with special reference to delayed charcoal administration, was investigated in a randomized study with four parallel groups of eight healthy volunteers. The first group ingested fluoxetine on an empty stomach with water only (control). The second group received 25 g of activated charcoal as a suspension immediately after fluoxetine. The third and fourth groups took fluoxetine with water and received 25 g of charcoal 2 or 4 hr after fluoxetine. Timed blood samples were taken and plasma fluoxetine and norfluoxetine concentrations were measured by GC for 96 hr. When charcoal was administered immediately after fluoxetine, the AUC (0‐96 hr) of fluoxetine was reduced by more than 96% (P<0.0005) and the Cmax by more than 98% (P<0.0005). The reduction in the AUC (0‐96 hr) and Cmax of norfluoxetine was similar to that of fluoxetine. When the administration of charcoal was delayed 2 or 4 hr, there was a non‐significant mean reduction of 16% and 23% in the AUC (0‐96 hr) of fluoxetine. Similarly, the Cmax was not significantly reduced by charcoal given 2 or 4 hr later. Also, the half‐life of fluoxetine was not significantly reduced (by 25%) by the late administration of charcoal. We conclude that activated charcoal, ingested immediately after fluoxetine, practically completely prevents the gastrointestinal absorption of fluoxetine. However, regardless of the relatively slow absorption of fluoxetine, delaying charcoal administration 2‐4 hr greatly reduces its antidotal efficacy.
Refinement and Validation of an Alternative Bioassay for Potency Testing of Therapeutic Botulinum Type A Toxin
Authors: Sesardic Dorothea , McLellan Kay , Ekong Theresa A. N. , Das Rose Gaines
Published: March 2009

Abstract:The type A neurotoxin produced byClostridium botulinumis a potent neuromuscular blocking agent which causes paralysis by preventing the release of neurotransmitter from motor neurones. This property has led to the use of the toxin in the treatment of a number of neuromuscular diseases involving muscle spasms. At present, the only recognised assay with the specificity and sensitivity to estimate accurately the potency of botulinum toxin in clinical preparations is bioassay, in which lethality is used as the end point. Refinement of this assay, with respect to the end point, was explored on the basis of the development of flaccid paralysis of muscles following subcutaneous injection of the toxin at the inguinocrural region. Potency estimates, relative to in house reference preparations, for different therapeutic preparations obtained using flaccid paralysis as a scored response gave excellent agreement with estimates obtained in independent assay using the currently required control method. This study demonstrates that an alternative, more humane bioassay for potency testing of clostridia neurotoxins gives valid estimates equivalent to those currently in use.
Aluminium Accumulation in Some Tissues of Rats with Compromised Kidney Function Induced by Cadmium‐Metallothionein
Authors: Liu Jenny , Nordberg Gunnar F. , Frech Wolfgang
Published: March 2009

Abstract:Two experiments (I and II) were performed to study aluminium accumulation in brain as well as in several other tissues in male Wistar rats. A single intraperitoneal injection of cadmium‐metallothionein (CdMT, 0.1‐0.4 mg Cd/kg b. wt.) was used to compromise kidney function 12 hr before the final aluminium injection in both experiments. In experiment I, rats were maintained on diets deficient (0.01%, w/w) in calcium (‐Ca) or providing adequate (+ Ca) dietary calcium (0.9%) for 6 weeks. Among animals given a daily intraperitoneal dose of aluminium chloride (10.8 mg Al/kg per day) on 6 consecutive days there was a tendency towards higher aluminium level in brains of rats with compromised kidney function from CdMT (in ‐Ca rats: the geometric mean [G] = 288 versus 205 ng/g wet weight [w., wt.], P=0.07, and in + Ca rats: G=242 versus 164, P<0.05) as compared to animals given no CdMT. The results from experiment II (all rats were given aluminium 5.6 mg Al/kg 2 and 12 hr after CdMT injection) demonstrated a higher level of aluminium (G: 41 ng/g w. wt., P<0.05) in brains of rats with only slightly damaged kidney function (0.1 mg Cd/kg) than in those given no CdMT (G: 29 ng/g w. wt.). It was also observed that 1) calcium deficiency had a statistically significant effect (P<0.05) in increasing kidney retention of intraperitoneal aluminium (G: 327 ug/g w. wt.) as compared to rats with a normal calcium supply in the diet (G: 54 ug/g w. wt.); 2) when aluminium concentration in kidney was at and above 54 ug/g wet tissue, kidney damage was observed. The above results indicate that compromised kidney function including tubular damage induced by a low‐dose of CdMT may play a crucial role in the accumulation of aluminium in brain and other tissues. Since tubular function decreases with age in human populations, these findings in rats may be of considerable importance if a similar phenomenon would occur in humans. Therefore, the possibility of increased aluminium retention in persons with low calcium and high aluminium intakes may need to be further investigated.
The σ ligand JO 1784 Prevents Trimethyltin‐Induced Behavioural and σ‐Receptor Dysfunction in the Rat
Authors: O'Connell Alan W. , Earley Bernadette , Leonard Brian E.
Published: March 2009

Abstract:Recently much research interest has focused on the possible therapeutic uses of σ‐receptor ligands in psychiatric and neurodegenerative disorders. In the present study, the potential neuroprotective effects of chronic (52 days) administration of (+) cinnamyl‐1‐phenyl‐1‐N‐methyl‐N‐cyclo propylene (JO 1784) (1 and 3 mg/kg subcutaneously), a potent and selective σ receptor ligand, were assessed in the trimethyltin (8 mg/kg intraperitoneally) model of memory dysfunction. JO 1784 (3 mg/kg subcutaneously) prevented the trimethylin‐induced deficits in locomotor activity, passive avoidance and radial maze performance, while the lower dose of JO 1784 had little or no effect. Trimethyltin was also shown to produce a marked reduction in the binding of [3H] (+)‐pentazocine to a‐receptor sites in limbic brain structures, as detected by quantitative autoradiography, which was particularly evident in the hippocampal pyramidal cells. JO 1784 (3 mg/kg subcutaneously) successfully attenuated this loss of [3H] (+)‐pentazocine binding sites in the hippocampus (CA1, CA3and CA4regions) and in the substantia innominata. This neuroprotective effect of JO 1784 in the trimethyltin model would seem to be related to the modulatory effects of this σ ligand on trimethyltin‐induced glutamate neurotoxicity.
Debrisoquin and S‐Mephenytoin Hydroxylation Phenotypes and CYP2D6 Genotypes in an Estonian Population
Authors: Marandi T. , Dahl M. L. , Kiivet R. A. , Rägo L. , Sjöqvist F.
Published: March 2009

Abstract:The polymorphisms of debrisoquin (CYP2D6) and S‐mephenytoin (CYP2C19) hydroxylation were studied in 210 unrelated healthy native Estonians by coadministration of mephenytoin and debrisoquin or dextromethorphan. Among the 210 volunteers 21 (10%) were poor metabolizers of debrisoquin/dextromethorphan and two (0.95%) were poor metabolizers of S‐mephenytoin. By pooling these data with an earlier study on 156 Estonians, the prevalences of poor metabolizers of debrisoquin/dextromethorphan and poor metabolizers of S‐mephenytoin were 7.6% and 2.2%, respectively. TheCYP2D6genotype of 151 subjects was analysed by allele‐specific PCR amplification for the defect allelesCYP2D6AandCYP2D6B. All poor metabolizers of debrisoquin carried two defectCYP2D6‐alleles. The phenotype (extensive or poor metabolizer) was in all subjects correctly predicted by the genotype. The frequencies of the defect allelesCYP2D6BandCYP2D6Aamong these 151 subjects (including 14 poor metabolizers ‐ 9.3%) were 21.5% and 2.3%, respectively. DNA from 6 subjects with very high CYP2D6 activity (debrisoquin MR<0.1) was analysed byEcoRI RFLP to identify duplicated or amplifiedCYP2D6‐genes. Two of the subjects were found to carry a duplicatedCYP2D6L‐gene. In conclusion, the distribution of genetically determined metabolic capacities of CYP2D6 and CYP2C19 in Estonian unrelated subjects did not differ significantly from that in other Caucasian populations. The CYP2D6 phenotype was predicted by PCR‐based amplification for theCYP2D6AandCYP2D6B‐aellels.