bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling of Non‐Linear Pharmacokinetics in Sheep after Short‐Term Infusion of Cardiotoxic Doses of Imipramine
Authors: Meineke Ingolf , Schmidt Wilhelm , Nottrott Markus , Schröder Thomas , Hellige Gerhard , Gundert‐Remy Ursula
Published: March 2009

Abstract: Imipramine was administered to sheep (n= 10) by intravenous infusion in high doses (450 mg‐900 mg) to elicit cardiovascular shock. A cardiac assist device was then employed to manage the acute overdose situation. The concentration‐time course of imipramine and its metabolite desmethylimipramine in plasma was measured by HPLC. As an indicator of imipramine's cardiotoxic effect, cardiac output was monitored. The aim of the study was to evaluate the pharmacokinetics under these conditions and to assess the efficiency of a cardiac assist device with (n=5) and without (n=5) an integrated haemoperfusion unit in removing drug from the circulation. The kinetics of imipramine could be described by a three compartment body model with concentration‐dependent clearance resulting in non‐linear kinetics. The changes in cardiac output with time could be linked to the pharmacokinetic model by a linear relationship. The cardiac assist device was found to contribute to the overall elimination of imipramine whereas the haemoperfusion unit had no clinically relevant impact.
Relaxation of Rat Resistance Arteries by Acetylcholine Involves a Dual Mechanism: Activation of K+Channels and Formation of Nitric Oxide
Authors: Hansen Peter Riis , Olesen Søren‐Peter
Published: March 2009

Abstract:The relaxation of rat mesenteric resistance arteries to acetylcholine was studied in vessels (normalised internal diameter 230–330 μm) mounted in an isometric myograph and contracted with noradrenaline (5 μM). Removal of the endothelium abolished acetylcholine‐induced vasorelaxation, whereas pretreatment with NG‐nitro‐L‐arginine (500 μM) only inhibited the response partly. The relaxation was, however, completely inhibited by NG‐nitro‐L‐arginine when the arteries were contracted with 80 mM K+. Acetylcholine‐induced vasorelaxation was also attenuated by pretreatment with the K+channel blocker, iberiotoxin (100 nM), and the combined pretreatment with iberiotoxin+NG‐nitro‐L‐arginine completely blocked vasorelaxation to acetylcholine. Further, vasorelaxation to acetylcholine was attenuated by tetraethylammonium (5 mM), 4‐aminopyridine (1 mM), and BaCl2(100 μM), respectively, whereas glibenclamide (1 μM) and indomethacin (10 μM) were devoid of effect. Vasorelaxation to the nitric oxide donor sodium nitroprusside was not influenced by iberiotoxin. We conclude that in rat mesenteric resistance arteries, there is a significant nitric oxide‐independent component of acetylcholine‐induced vasorelaxation, which is mediated by activation of several types of K+channels, in particular large conductance Ca2+‐dependent K+channels.
Blood and Plasma Lipoprotein Distribution and Gender Differences in the Plasma Pharmacokinetics of Lipid‐Associated Annamycin
Authors: Wasan Kishor M. , Kwong Mona
Published: March 2009

Abstract: The objectives of this study were to determine the lipoprotein distribution of unbound annamycin and liposomal annamycin within human and rabbit blood and plasma and to evaluate the plasma pharmacokinetics of liposomal annamycin in male and female rabbits following a single intravenous bolus of the compound. Annamycin and liposomal annamycin were incubated in human and rabbit blood and plasma for 60 min. at 37°C. Following incubation blood and plasma samples were assayed by HPLC for drug in each of the lipoprotein and lipoprotein‐deficient plasma fractions. To evaluate the plasma pharmacokinetics of liposomal annamycin in male versus female rabbits, a single intravenous bolus dose (5 mg/kg) of liposomal annamycin was administered to male and female rabbits. Sequential blood samples were obtained from the animals following the dose, analyzed for drug, and the pharmacokinetics determined using multicompartmental methods. The incorporation of annamycin into liposomes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol resulted in no significant differences in blood versus plasma lipoprotein drug distribution. Furthermore, no differences in the plasma distribution of liposomal annamycin were observed when the drug was either incubated in vitro for 1 hr or 1 hr following intravenous administration into New Zealand male white rabbits. The plasma clearance and volume of distribution of liposomal annamycin were decreased and a increase in plasma AUC in female as compared to male rabbits following a single intravenous bolus of liposomal annamycin was observed. These findings suggest that the lipoprotein distribution of liposomal annamycin is not different when incubated in blood or plasma and that in vitro liposomal annamycin plasma distribution is similar to in vivo. Furthermore, it appears that the pharmacokinetics of liposomal annamycin are different following administration to male versus female rabbits.
Nutrition of (Göttingen) Minipigs: Facts, Assumptions and Mysteries
Authors: Ritskes‐Hoitinga J. , Bollen P.
Published: March 2009

Abstract: Detailed guidelines are available concerning the nutrient requirements of pigs (National Research Council 1988). These nutrient requirements are based on ad libitum feeding and obtaining maximum growth, as they have originated from feeding schedules for slaughter pigs. Whether these nutrient guidelines for pigs can be applied to minipigs as well remains to be answered. Moreover, ad libitum feeding and maximum growth are not considered the optimum in scientific research. The German Society for Laboratory Animal Science has published guidelines for the composition of minipig diets, mainly based on empirical results (1993). Upon comparison of dietary guidelines for pigs and minipigs, differences can be found. At the moment it is unclear which of the two dietary guidelines guarantees that all minimum nutrient requirements of the minipig are met. Restricted feeding is often applied in studies using minipigs, in order to prevent obesity. As the two guidelines are based on ad libitum feeding, this raises the question whether restriction results in (marginal) nutrient deficiencies, which may interfere with experimental results.
Characterization of the P450 System in Göttingen Minipigs
Authors: Skaanild Mette T. , Friis Christian
Published: March 2009

Abstract:It is essential to establish the activity and regulation of the cytochrome P450 system of species selected for toxicological and pharmacological studies. The minipig has become a popular substitute for the traditional non‐rodent species although little information is available on its P450 system. The total P450 and the enzyme activity of the most important drug‐metabolizing isoenzymes: CYP1A2, CYP2C19, CYP2D6, CYP2E1 and CYP3A4 were measured in liver microsomes from 4 minipigs and 8 conventional pigs of both sexes. Immunochemical levels were determined for 4 of the isoenzymes. The total P450 activity was slightly higher in minipigs compared to conventional pigs but no sex difference was detected. CYP1A2 activity (7‐ethoxyresorufin) was 4 times higher in female minipigs than in male minipigs. The activity in male minipigs was almost identical to the activity in conventional pigs. The activity of CYP2E1 (chlorzoxazone) was 4 times higher in female than in male minipigs and 2 times higher in female than in male conventional pigs. No activity of CYP2D6 (debrisoquine) and CYP2C19 (mephenytoin) could be detected. The CYP3A4 activity (testosterone) detected in minipigs was higher than the activity in conventional pigs. A weak sex difference was seen in both strains. Western blotting using anti‐human CYP2E1 and CYP3A4 confirmed the results obtained in the enzyme activity assays, while only CYP1A2 correlated with the activity in the conventional strain. The total P450 enzyme activity was close to the levels reported for human beings, as were the activities of CYP2E1 and CYP3A4.
Alterations of Physostigmine‐Induced Yawning by Chronic Lithium Administration in Rats
Authors: Sharifzadeh Mohammad , Abdollahi Mohammad , Dehpour Ahmad‐Reza , Kebriaeezadeh Abbas , Samini Mortaza , Mohammad Marjan
Published: March 2009

Abstract:The effect of chronic lithium pretreatment on physostigmine‐induced yawning was investigated in male rats. Intraperitoneal administration of physostigmine to rats induced yawning in a biphasic manner. However the maximum response was obtained by 0.2 mg/kg of the drug. Intracerebroventricular administrations of a putative M1and M2muscarinic receptor antagonists, pirenzepine and methoctramine decreased physostigmine‐induced yawning. Intraperitoneal administration of a non‐selective muscarinic receptor antagonist, atropine, also decreased the physostigmine‐induced yawning significantly. Chronic lithium pretreatment (30 days) reduced yawning induced by physostigmine. The inhibitory effect of pirenzepine. methoctramine and atropine on physostigmine‐induced yawning increased in rats pretreated with chronic lithium. These findings indicate that yawning is induced by a central cholinergic mechanism and that chronic pretreatment of lithium may interact with the cholinergic‐induced behaviour.
Antimuscarinic Potency and Bladder Selectivity of PNU‐200577, a Major Metabolite of Tolterodine
Authors: Nilvebrant Lisbeth , Gillberg Per‐Göran , Sparf Bengt
Published: March 2009

Abstract:PNU‐200577 (labcode DD 01 [(R)‐N,N‐diisopropyl‐3‐(2‐hydroxy‐5‐hydroxymethylphenyl)‐3‐phenylpropanamine) is a major pharmacologically active metabolite of tolterodine, a new muscarinic receptor antagonist intended for the treatment of an overactive bladder.In virro, PNU‐200577 produced a competitive and concentration‐dependent inhibition of carbachol‐induced contraction of guinea‐pig isolated urinary bladder strips (KB=0.84 nM; pA2=9. 14).In vivo, PNU‐200577 was significantly more potent at inhibiting acetylcholine‐induced urinary bladder contraction than electrically induced salivation in the anaesthetised cat (ID5015 and 40 nmol. kg−l, respectively; P<0.0l). In radioligand binding studies carried out in homogenates of guinea‐pig tissues and Chinese hamster ovary cell lines expressing human muscarinic ml‐m5 receptors, PNU‐200577 was not selective for any muscarinic receptor subtype. Thus, PNU‐200577 is similar to tolterodine in terms of antimuscarinic potency, functional selectivity for the urinary bladderin vivoand absence of selectivity for muscarinic receptor subtypesin vitro. The results of this study clearly indicate that PNU‐200577 contributes to the therapeutic action of tolterodine, in view of its high antimuscarinlc potency, similar serum concentration and lower degree of protein binding.
Protection by 4‐Methylthiobenzoic Acid Against Cisplatin‐Induced Ototoxicity: Antioxidant System
Authors: Rybak Leonard P. , Husain Kazim , Evenson L. , Morris Craig , Whitworth Craig , Somani Satu M.
Published: March 2009

Abstract: This study was undertaken in order to determine the changes in auditory brainstem‐evoked responses relationship with the changes in the levels of GSH, lipid peroxidation and antioxidant enzymes activity in cisplatin‐induced ototoxicity and otoprotection by 4‐ methylthiobenzoic acid (MTBA). Male Wistar rats in different groups were treated as follows: 1) saline control; 2) cisplatin (16 mg/kg, intraperitoneally); 3) MTBA (250 mg/kg, intraperitoneally), and 4) cisplatin plus MTBA. Post‐treatment auditory brainstem‐evoked responses were performed after three days and the rats were sacrificed and cochleae harvested. The cochleae were analyzed for glutathione (GSH), antioxidant enzyme activity, and malondialdehyde levels. The cisplatin injected rats showed a threshold elevation of 31.9+16.0 dB above the pretreatment thresholds using click stimulus. Rats treated with MTBA plus cisplatin did not show significant elevation of hearing threshold. Cisplatin plus MTBA administration showed a higher levels of cochlear GSH (5.59+0.35 nmoles/mg protein) compared to cisplatin alone (4.46+0.13 nmoles/mg protein). Cisplatin treated rats showed a decrease in superoxide dismutase, catalase, glutathione peroxidase (GSH‐peroxidase), and glutathione reductase (GSH‐reductase) activities (57%, 83%, 78% and 58% of control). Cochlear superoxide dismutase, catalase and GSH‐reductase activities and MDA levels were restored in the rats injected with cisplatin plus MTBA, compared to cisplatin alone. It is concluded that the protection conferred by MTBA against cisplatin ototoxicity is associated with sparing of the cochlear antioxidant system.
Expression of Cytochrome P450 Genes Encoding Enzymes Active in the Metabolism of Tamoxifen in Human Uterine Endometrium
Authors: Hukkanen Janne , Mantyla Marjatta , Kangas Lauri , Wirta Pauli , Hakkola Jukka , Paakki Pauliina , Evisalmi Sari , Pelkonen Olavi , Raunio Hannu
Published: March 2009

Abstract: Long‐term tamoxifen therapy is associated with increased risk of uterine endometrial cancer and benign alterations. Tamoxifen is metabolized to reactive intermediates by endometrial tissue, and tamoxifen therapy‐induced DNA adducts have been found in human endometrium. Since metabolic activation is often catalyzed by cytochrome P450 (CYP) enzymes, the expression profile of individual xenobiotic‐metabolizing CYP genes was studied in human uterine endometrium by reverse transcriptase‐polymerase chain reaction. The following CYP mRNAs were detected: CYP2B6. CYP2C, CYP2E1, CYP3A4, CYP3A5, CYP4B1, and CYP11A. Amplification of CYP1AI, CYP1A2, CYP2A6, CYP2D6. CYP2F1, CYP3A7, and CYP19 was not found. CYP3A5 and CYP4B1 transcripts were found only in samples from premenopausal women. These data suggest that the human endometrial epithelium has the potential of producing CYP enzymes known to generate genotoxic intermediates from tamoxifen and metabolites that affect oestrogen receptors.
Disodium Cromoglycate is Neither Cytotoxic nor Genotoxie in Mammalian Cells in vitro
Authors: Dušinská Mária , Jurák Branislav , Vlčková Angelika , Horáková Katarína
Published: March 2009

Abstract: The cytotoxic and genotoxie effects of disodium cromoglycate on mammalian cells were investigated. We used two types of hamster cells, a primary culture of Syrian hamster embryo cells and the cell line V79‐4. Cytotoxicity was studied by using proliferation and plating efficiency assays. No toxic effect of disodium cromoglycate on hamster cells in the tested concentration range (2.4 48 μM) was observed. The growth of treated V79 cells was slightly stimulated during proliferation compared with control cells. This stimulation was not observed in the stationary phase of growth. Plating experiments confirmed that disodium cromoglycate has no cytotoxic effect on V79 cells. The genotoxicity of disodium cromoglycate (up to concentration 96 μM) was studied in both cell types using two assays, the DNA synthesis inhibition test and alkaline DNA unwinding with hydroxyapatite chromatography. In V79 cells, disodium cromoglycate had no effect on DNA synthesis. In Syrian hamster embryo cells disodium cromoglycate acts as a mild metabolic inhibitor of DNA synthesis. This effect is reversible. No single‐strand breaks were found after treatment with disodium cromoglycate in either cell type. These results confirm that disodium cromoglycate is without cytotoxic effect (up to 48 μM) and, furthermore, lacks genotoxicity at least up to 96 μM.
Pharmacological Screening of DifferentJuniperus oxycedrusL. Extracts
Authors: Moreno L. , Bello R. , Beltrán B. , Calatayud S. , Primo‐Yúfera E. , Esplugues J.
Published: March 2009

Abstract:Methanol and dichloromethanol extracts of leaves and stems ofJuniperus oxycedrushave been tested for their toxicity, analgesic, antiinflammatory and central effects. Both extracts showed low acute toxicity and decreased spontaneous motility. The methanol extract exhibited an analgesic effect in models of chemical, mechanical and thermal stimulation whereas dichloromethanol extract showed only a significant effect in models of pain induced by chemical stimulation. Both extracts showed a significant antiinflammatory activity and inhibition of the rat paw oedema induced by carrageenin.
The Effect of 1,25‐Vitamin D3 on Calbindin‐D and Calcium‐Metabolic Variables in the Rat
Authors: Hemmingsen Claus , Staun Michael , Olgaard Klaus
Published: March 2009

Abstract: Intraperitoneal injection of l,25‐(OH)2D3 4 μg/kg was given to 84 calcium‐ and vitamin D‐repleted Wistar rats and samples of plasma, duodenal mucosa and renal tissue were taken after 0, 3, 6, 12, 24, 48 and 96 hr (n = 12 at each time interval). Plasma‐ionized Ca increased after 6 hr, reached a maximum after 24 hr and returned to the initial values after 96 hr. The concentrations of renal ealbindin‐D28k and intestinal calbindin‐D9k did not increase until 48 hr after injection and remained elevated until 96 hr after. Therefore, significantly elevated concentrations of the cytosolic calbindinD were found at a time with normal values of plasma Ca. The present data suggest that calbindin‐D does not alone increase the transcellular Ca transport and, therefore, supports the view that calbindin‐Ds may serve as Ca buffer proteins.
Cross‐Fostering Study of Methyl Mercury Retention, Demethylation and Excretion in the Neonatal Hamster
Authors: Nordenhäll Kerstin , Dock Lennart , Vahter Marie
Published: March 2009

Abstract: The cross‐fostering technique was used in order to compare methyl mercury (MeHg) metabolism in hamsters following prenatal (in utero) and neonatal (lactational) exposure. Pregnant Syrian golden hamsters were administered radiolabeled MeHg on day 12 of gestation. The offspring was nursed by foster mothers unexposed to MeHg, while the pups from the unexposed animals were nursed by the MeHg‐administered animals. Under these conditions, each pup in the litter received a dose of MeHg in utero corresponding to 0.9% of the maternal dose. The average amount of mercury found in the pups exposed via milk corresponded to 4.5% of the total body burden of the foster dam at the onset of lactation. This was about half the amount received by the pups exposed in utero. The total body burden of mercury, and the amount of mercury in the liver, brain and kidney of the pups exposed in utero began to decrease at seven days of age. The rate of decrease differed among the tissues and was lowest in the kidney. The amount of mercury in pups exposed via milk reached a peak level when the pups were 10‐15 days old. The total body burden of mercury showed a slow decrease while the liver, brain and kidney levels decreased rapidly. In both groups of animals, up to 80% of the total body burden of mercury was found in the pelt. These data show that milk may be a significant exposure route for mercury and that neonatal hamsters are unable to demethylate MeHg and excrete mercury in urine and faeces.
The Effect of Acute Lithium and Rubidium Pretreatment on Apomorphine‐Induced Pecking in Pigeons
Authors: Dehpour Ahmad Reza , Samini Morteza , Aliebrahimi Fateme , Chavoushzadeh Mir Ali
Published: March 2009

Abstract:The effects of different doses of lithium (5‐320 mg/kg intramuscularly) and rubidium (0.25‐32 mg/kg intramuscularly) on apomorphine‐induced pecking were investigated in pigeons. These two cations did not induce pecking by itself. Intramuscular administration of apomorphine (a mixed D1/D2 dopamine receptors agonist, 0.1‐1.6 mg/kg) induced pecking in a dose‐dependent manner. SCH 23390 (Dl dopamine receptor antagonist, 0.02‐0.08 mg/kg) and sulpiride (D2 dopamine receptor antagonist, 25‐100 mg/kg) decreased apomorphine‐induced pecking dose‐dependently. Combination of SCH 23390 (0.04 mg/kg) with sulpiride (50 mg/kg) caused a stronger inhibitory effect on apomorphine response. This indicates that both Dl and D2 dopamine receptors are involved in apomorphine‐induced pecking. The response induced by apomorphine (0.2‐0.8 mg/kg) was decreased in animals pretreated with lithium and rubidium. In these conditions, SCH 23390 and sulpiride produced a larger inhibitory effect on the apomorphine response, suggesting that acute lithium and rubidium pretreatment inhibit pecking by interfering with dopaminergic mechanisms.
Tolbutamide: Placental Transfer, Tissue Distribution, and Metabolic Effects in Murine Embryos
Authors: Smoak Ida W. , Emanuel Andrea N.
Published: March 2009

Abstract: Tolbutamide is a sulfonylurea oral hypoglycaemic agent with suspected teratogenicity in humans and demonstrated teratogenicity in laboratory animals, but the underlying mechanism is unknown. This study examined maternalto–conceptus tolbutamide transfer on gestational days 9.5 and 10.5 and drug concentration in embryonic head, heart, and trunk regions on gestational day 10.5 after maternal dosing in mouse. Embryos exposed to tolbutamide in vitro on gestational day 8.5 were assayed for glucose uptake, glycolysis, and protein content after 6, 12, and 24 hr. Dose–dependent tolbutamide transfer from maternal serum to extraembryonic fluid occurred on gestational day 9.5 and 10.5, with highest tolbutamide levels in embryonic heart on gestational day 10.5. In vitro tolbutamide exposure on gestational day 8.5 decreased glycolysis at 6 hr, increased glycolysis at 24 hr. and had no effect on glucose uptake at 6, 12, or 24 hr. Embryonic protein content reflected growth retardation after 24 hr tolbutamide exposure. Thus, mouse embryos are directly exposed to tolbutamide after maternal dosing on gestational day 9.5 and 10.5, with concentration of drug within embryonic heart. Tolbutamide–induced changes in glucose metabolism are less apparent in whole embryos than reported in adult tissues.
Gadolinium Chloride Inhibition of Pulmonary Nitric Oxide Production and Effects on Pulmonary Circulation in the Rabbit
Authors: Adding L. Christofer , Bannenberg Gerard L. , Gustafsson Lars E.
Published: March 2009

Abstract:Nitric oxide is an important regulator of pulmonary vascular resistance. Pulmonary nitric oxide formation is detectable in exhaled air and the synthesis is partly stretch‐dependent. Gadolinium chloride (GdCl3) reduces pulmonary nitric oxide formation, possibly by interference with stretch‐activated cellular calcium influx, but the effect on pulmonary circulation is not known. We therefore measured exhaled nitric oxide and pulmonary vascular resistance in anaesthetised rabbits, and compared the effects of GdCl3with those of an nitric oxide‐synthase inhibitor (L‐Nω‐nitro‐arginine methyl ester, L‐NAME). Both GdCl3and L‐NAME reduced nitric oxide in exhaled air and increased pulmonary vascular resistance. However, the increase in pulmonary vascular resistance was more pronounced with GdCl3than with L‐NAME. A 50% reduction of exhaled nitric oxide caused by either GdCl3or L‐NAME was accompanied by a 90% or 17% increase in pulmonary vascular resistance respectively. Inhaled nitric oxide (40 ppm) reduced pulmonary vascular resistance after L‐NAME, but not after GdCl3infusion. Infusion of glyceryltrinitrate reduced pulmonary vascular resistance after GdCl3infusion. GdCl3caused hypoxaemia, probably due to vasoconstriction since lung weight was unaltered. Thus GdCl3can induce a marked increase in pulmonary vascular resistance, which partly may be caused by inhibition of pulmonary nitric oxide formation. Intact stretch‐activated calcium channels may be important for maintenance of normal pulmonary vascular function.
In vitro Screening for Metabolic Interactions among Frequently Occurring Binary Mixtures of Volatile Organic Chemicals in Norwegian Occupational Atmosphere
Authors: Mortensen Bjarte , Osvoll Peter O. , Woldbæk Torill , Zahlsen Kolbjørn , Eide Lngvar , Nilsen Odd G.
Published: March 2009

Abstract: Surveys of Norwegian industrial occupational atmosphere between 1983 to 1996, have identified the 12 most frequent occurring binary combinations of volatile organic chemicals. These combinations were tested in vitro for mutual inhibition or enhancement of metabolism by the head space vial equilibration technique with liver S9 obtained from in vivo untreated or pretreated (with the binary mixture) rats. The in vitro system responded to in vivo pretreatment by increasing the metabolic rate of several potentially toxic organic chemicals such as toluene, xylene, styrene, and dichloromethane. In untreated liver S9, the metabolism of several of the tested binary pairs was inhibited when coexposed in vitro to their most prevalent follower as shown for instance for ethanol (with ethyl acetate), dichloromethane (with styrene) and mutually between toluene and xylene. This inhibitory effect disappeared, however, for several of the solvents when combined with the in vivo induced liver S9, a situation which may be the most relevant for occupational exposure. It is concluded that several metabolic interactions occur between low‐molecular weight volatile chemicals found in occupational air. These are both inductive and inhibitory in nature and a further mechanistic evaluation including a higher number of differentiated dosage levels, must be performed before a possible health hazard can be confirmed or rejected for the investigated combinations.
Apoptosis in Embryos of Diabetic Rats
Authors: Forsberg Henrik , Eriksson Ulf J. , Welsh Nils
Published: March 2009

Abstract: The aim of the present study was to determine whether maternal diabetes affects rat embryo and yolk sac apoptosis during the postimplantation period. Severely malformed and growth‐retarded embryos of gestational day 12 from diabetic rats exhibited pronounced DNA laddering on agarose gels. On the other hand, no DNA laddering could be observed in any of the non‐malformed embryos from control and diabetic rats, or in their corresponding yolk sacs. Analysis of embryos of gestational day 10 revealed only a few scattered TUNEL positive cells mainly located in the allantois, the foregut epithelium, the cranial neuroepithelium and in the cranial mesenchyme. Embryonic tissue of gestational day 12 showed numerous aggregates of TUNEL‐positive cells, indicating developmental remodelling of multiple organs. Analysis of non‐malformed embryos of day 10 and 12 revealed a distribution and frequency of TUNEL positive cells unaffected by the diabetic state of the mother on both days. In vitro incubation (2–8 hr) of normal day‐12 yolk sacs resulted in strong DNA laddering, but not in the corresponding embryos. Dispersed yolk sac cells generated higher levels of reactive oxygen species than dispersed embryonic cells. Reactive oxygen species levels in both embryonic and yolk sac cells were unaffected by the diabetic state of the mother. Moreover, immunoblot analysis showed high Bcl‐2 and undetectable caspase‐1 levels in embryos from both normal and diabetic rats and low Bcl‐2 and high caspase‐1 levels in the corresponding yolk sacs. Immunohistochemical analysis of embryos demonstrated caspase‐1‐reactivity in a small subpopulation of cells located in proximity to TUNEL‐positive cells. We conclude that the inherent capacity of embryonic cells to enter apoptosis in vitro is low as compared to yolk sac cells, and that wide‐spread apoptosis is not likely to play a major role in diabetes‐induced dysmorphogenesis but rather in early phases of resorption of severely malformed and developmentally retarded embryos.
Respiratory Effects in Mice Exposed to Airborne Emissions fromStachybotrys chartarumand Implications for Risk Assessment
Authors: Wilkins Cornelius Kendall , Larsen Søren Thor , Hammer Maria , Poulsen Otto Melchior , WWkoff Peder , Nielsen Gunnar Damgård
Published: March 2009

Abstract: Stachybotrys chartarum, a mycotoxin producing mould found in some damp buildings, was grown in aluminum dishes in closed exposure chambers. The loading factor, 5.12 m2/m3, corresponded to 2.8 times the loading in a normal room with all surfaces covered by mould. Sensory irritation, bronchoconstriction and pulmonary irritation effects were investigated using a sensitive mouse bioassay in which the airway reactions were measured plethysmographically. Little effect was seen from the vapours in agreement with the predicted effects of the low concentrations of volatile organic compounds measured. Even under the influence of an airflow about four times that measured in normal buildings, the concentration of liberated spores and other particles was very low, corresponding to the biological effects observed, and probably reflecting the high water content of the substrate. These results demonstrate that many factors are important for the transport of biologically active mould metabolites from building material to occupants and that no direct relationship may exist between immediate biological effects and surface area covered with mould. Therefore, risk assessments should be based on estimated effects of emitted vapours, effects of liberated particles, e.g. sensitization potentials of the mould spores and effects of the generated metabolites (mycotoxins).
Pharmacokinetics and Oral Bioavailability of Glycopyrrolate in Children
Authors: Rautakorpi Pirkka , Manner Tuula , Ali‐Melkkilä Timo , Kaila Timo , Olkkola Klaus , Kanto Jussi
Published: March 2009

Abstract: Based on plasma levels determined with a radioreceptor assay and following a single oral (50 μg/kg) and intravenous (5 μg/kg) administration of glycopyrrolate in six healthy children operated twice during a several weeks period, a negligible and variable oral bioavailability was found (3.3; 1.3–13.3%) (median; range). No significant changes in heart rate after oral or intravenous administration of the drug could be seen. Oral glycopyrrolate appears to have no place in paediatric premedication.
Carbonyl Reduction of Timiperone in Human Liver Cytosol
Authors: Shimoda Kazutaka , Shibasaki Morikazu , Lnaba Tadanobu , Cheung Siu Wah , Someya Toshiyuki , Takahashi Saburo
Published: March 2009

Abstract:Thisin vitrostudy using human liver enzymes was undertaken in order to compare the mechanism of metabolic reduction of timiperone, a potent butyrophenone neuroleptic, with that of haloperidol. Conversion of timiperone to reduced timiperone in liver cytosol was confirmed. The carbonyl reductase inhibitors (menadione IC505–18 μM; ethacrynic acid IC5026–51 μM) potently inhibited both timiperone reductase and haloperidol reductase activity, while 4‐methyl‐pyrazole (alcohol dehydrogenase inhibitor) had no effect and phenobarbital (aldehyde reductase inhibitor) had a weak inhibitory effect. The formation of reduced timiperone was highly correlated with the formation of reduced haloperidol(r= 0.87, n=6, P<0.02). Timiperone reductase activity was approximately 40% lower than haloperidol reductase activity (at a substrate concentration of 100 μM, two‐tailed t‐test, P<0.05). The Michaelis‐Menten constant (Km) and maximum velocity (Vmax) of reduced timiperone formation were much lower than reduced haloperidol formation (Kmvalues: 29.7 + 15.1 versus 381.3 + 1.1 μM, n=3, P<0.01; Vmax: 0.81 + 0.19 versus 6.00 + 1.47 nmol/mg/min; n=3, P<0.05). However, the ratio Vmax/Km(clearance) for timiperone was 1.3–2.4 times higher than for haloperidol, indicating that metabolic clearance of timiperone by carbonyl reductase may be similar to or slightly higher than for haloperidol.
Inhibition of Nicotinic Responses by Cotinine in Bovine Adrenal Chromaffin Cells
Authors: Vainío Petri J. , Viluksela Matti , Tuominen Raimo K.
Published: March 2009

Abstract:We studied the effects of cotinine, the major metabolite of nicotine, on nicotine‐induced increase in [3H]phorbol dibutyrate binding, activation of protein kinase C and [3H]noradrenaline release in primary cultured bovine adrenal chromaffin cells. Cotinine (1 mM, 15 min.) and nicotine (10 μM, 5 min.) increased the [3H]phorbol binding by 100% and 150%, respectively. Both a short‐term (10 min.) and a long‐term (24 hr) pretreatment with cotinine inhibited the effect of nicotine. A 24 hr pretreatment with cotinine (1 mM) also reduced the nicotine‐induced increase in membrane‐bound protein kinase C activity. Cotinine pretreatment (10 min.) dose‐dependently inhibited the release of [3H]noradrenaline induced by nicotine and dimethylphenylpiperazinium. Cotinine pretreatment did not reduce the [3H]noradrenaline release induced by high extracellular potassium (56 mM) or veratrine (10 mg l–1)‐ The results indicate that cotinine inhibits activation of protein kinase C and noradrenaline release induced by nicotinic agonists in primary cultures of bovine adrenal chromaffin cells. The results suggest that pre‐existing cotinine could modify responses to acute exposure to nicotine in neural systems.
Fluvoxamine is a Potent Inhibitor of the Metabolism of Caffeinein vitro
Authors: Rasmussen Birgitte Buur , Nielsen Torben Leo , Brøsen Kim
Published: March 2009

Abstract:The selective serotonin re‐uptake inhibitor, fluvoxamine, is a very potent inhibitor of CYP1A2, and accordingly causes pharmacokinetic interactions with drugs metabolised by CYP1A2, such as caffeine, theophylline, imipramine, tacrine and clozapine. Interaction between caffeine and fluvoxamine has been describedin vivo, leading to lowering of total clearance of caffeine by 80% during fluvoxamine intake. The main purpose of the present study was to evaluate this interactionin vitroin human liver microsomes. A high‐performance liquid chromatography method was developed in order to assay 1, 3‐dimethylxanthine, 1, 7‐dimethylxanthine, 3, 7‐dimethylxanthine and 1, 3, 7‐trimethyluric acid formed from caffeine by human liver microsomes. The limit of detection was 0.06 nmol · mg protein−1· hr−1. As expected, fluvoxamine was a very potent inhibitor of the formation of theN‐demethylated caffeine metabolites, displaying Kivalues of 0.08–0.28 μM. The formation of 1, 7‐dimethylxanthine was virtually abolished by 10 μM of fluvoxamine, indicating that theN3‐demethylation of caffeine is almost exclusively catalysed by CYP1A2. The CYP3A4 inhibitors, ketoconazole and bromocriptine, inhibited 1, 3, 7‐trimethyluric acid formation with K s of 0.75 μM and 5 μM, respectively, thus further supporting the involvement of CYP3A4 in the 8‐hydroxylation of caffeine. The study shows that fluvoxamine, as expected, is a potent inhibitor of the metabolism of caffeinein vitro.
Differential Inhibition of Morphine Glucuronidation in the 3–and 6–Position by Ranitidine in Isolated Hepatocytes from Guinea Pig*
Authors: Aasmundstad Tor A. , Mørland Jørg
Published: March 2009

Abstract:The influence of ranitidine on morphine metabolism, with special emphasise on the ratio between morphinc–3–glucuronide and morphine–6–glucuronide was studied in isolated guinea pig hepatocytes. Ranitidine reduced the Kelof morphine dose–dependently with a maximum effect of 50%, and increased the relative concentration of morphine–6–glucuronide to morphine–3–glucuronide. These effects could be due to a direct or indirect effect on the conjugation enxymes involved, or an effect on the transport of morphine or glucuronides across cell membranes. The latter explanation was rejected on the basis of the observation that the ratios between intra– and extracellular concentrations of morphine, morphine–3–glucuronide and morphine–6–glucuronide were not influenced by ranitidine. Increasing concentrations of ranitidine gradually decreased the morphine–3–glucuronide/morphine–6–glucuronide ratio by up to 21%. This could stem from interference of energy or co–substrate supply, or through direct effects on the different UDPGTases involved. The observation that the present effect on morphine glucuronidation was the opposite of that observed when administering a known co–substrate (UDPGA) depletor, indicated that in all probability the effect of ranitidine was a direct inhibition on the uridine 5′–diphosphate glucuronyltransferases involved, with a more pronounced effect for the isoenzymes responsible for the 3′–glucuronidation.
Reduction by Tetrahydrobiopterin of H2O2–Induced Endothelial Cell Injury
Authors: Ishii Masakazu , Shimizu Shunichi , Momose Kazutaka , Yamamoto Toshinori
Published: March 2009

Abstract: The purpose of this study was to examine the effect of tetrahydrobiopterin, a co–factor of nitric oxide synthase, on H2O2–induced endothelial cell injury. Pretreatment with sepiapterin, a precursor of tetrahydrobiopterin biosynthesis, increased tetrahydrobiopterin content of endothelial cells, and reduced H2O2–induced endothelial cell injury, which was measured by leakage of lactate dehydrogenase. Both the increase in tetrahydrobiopterin content and the protective effect of sepiapterin were prevented by co–pretreatment with N–acetylserotonin, an inhibitor of sepiapterin reductase. Although Ca2+ ionophore ionomycin–induccd nitric oxide synthesis was increased by pretreatment with sepiapterin, the protective effect of sepiapterin was not affected by an inhibitor of nitric oxide synthesis. On the other hand, pretreatment with sepiapterin also reduced H2O2–induced rat foetal lung fibroblast cell injury via an increase in tetrahydrobiopterin content, despite rat foetal lung fibroblast cells lacking nitric oxide synthase. Moreover, increase in tetrahydrobiopterin strongly reduced H2O2–induced intracellular oxidative stress. These findings indicate that sepiapterin reduces H2O2–induced endothelial cell injury via an increase in tetrahydrobiopterin content. Although increase in endothelial tetrahydrobiopterin content stimulated nitric oxide production, the protective effect of tetrahydrobiopterin against H2O2–induced endothelial cell injury is unlikely to be related to the stimulation of nitric oxide release from nitric oxide synthase. The protective effect of tetrahydrobiopterin may involve reactive oxygen species–scavenging activity.
The Drinking Water Chlorination By‐products 3,4‐Dichloro‐5‐hydroxy‐2[5H]‐furanone (Mucochloric Acid) and 3‐Chloro‐4‐(dichloromethyl)‐5‐hydroxy‐2[5H]‐furanone Do Not Induce Preneoplastic or Neoplastic Intestinal Lesions in F344 Rats, Balb/cA Mice or C57BL/6J‐Min Mice
Authors: Steffensen Inger‐Lise , Paulsen Jan Erik , Engeset Dagrun , Kronberg Leif , Alexander Jan
Published: March 2009

Abstract: Epidemiological studies indicate an association between exposure to chlorinated drinking water and risk of intestinal cancer. In order to study this experimentally, we have examined the effects of 3,4‐dichloro‐5‐hydroxy‐2[5H]‐furanone (mucochloric acid, MCA) and 3‐chloro‐4‐(dichloromethyl)‐5‐hydroxy‐2[5H]‐furanone (MX), mutagenic and genotoxic compounds in drinking water, on aberrant crypt foci and tumours in the intestines of male F344 rats and Balb/cA mice, and C57BL/6J‐Min (multiple intestinal neoplasia)/+ mice of both sexes, in six independent experiments. In some experiments the effects of MCA and MX on aberrant crypt foci induced by the colon carcinogens 1,2‐dimethylhydrazine or its metabolite azoxymethane were also studied. Neither MCA nor MX alone induced aberrant crypt foci or intestinal tumours when given in drinking water. With this route of exposure neither MCA nor MX, when given in combination with 1,2‐dimethylhydrazine or azoxymethane, had any effect on the induction or growth of the aberrant crypt foci. Drinking water exposure of MX did not affect the number or growth of aberrant crypt foci or intestinal tumours in the Min/+ mice. When administered intrarectally MCA had a weak inducing effect on aberrant crypt foci in the colons of Balb/cA mice. Exposure to MCA and MX intrarectally apparently promoted the growth of aberrant crypt foci both in rats and mice, increasing the crypt multiplicity, aberrant crypts/aberrant crypt foci. Based on an overall evaluation of these experiments, the intestinal tract, at least in rats and mice, seems not to be a main target organ for effects of MCA or MX on preneoplastic or neoplastic development.
CYP1A1 and CYP1B1, Two Hydrocarbon‐Inducible Cytochromes P450, are Constitutively Expressed in Neonate and Adult Goat Liver, Lung and Kidney *
Authors: Eltom Sakina E. , Schwark Wayne S.
Published: March 2009

Abstract:The ontogeny of cytochrome P‐450 isozymes (P450) in goat liver, lung and kidney was studied using anion exchange HPLC separation of solublized microsomal proteins and Western immunoblotting. Comparison of the overall HPLC profile of goat P450 isozymes between liver, lung and kidney showed that while the P450's of goat liver were equally separated into five peaks of isozyme(s), only two peaks constitute the majority of P450 isozyme(s) in lung and kidney, thus demonstrating the tissue specific differences in P450 isozyme distribution in goats. Immunoblotting analysis using polyclonal antibodies against rat CYP1A1, and mouse CYP1B1, polyaromatic hydrocarbon‐regulated P450's, revealed that goat orthologs of CYP1A1 and CYP1B1 are expressed constitutively in goats. The CYP1A1 was expressed in goat liver and lung as early as 1st day of age, and the levels of its expression in adult lung and liver were, respectively, 1.3 and 5.5 pmol per mg microsomal proteins. CYP1B1 was expressed in goat livers in substantial levels as of 1 week of age and increased thereafter to reach approximately 4.5 pmol per mg microsomal proteins in adult livers, while low level was detectable only in adult but not neonate lung tissues. Furthermore, polyclonal antibodies against rat CYP1A2 detected very high levels of CYP1A2 in livers of adult and 6 week old goats. The Ah receptor which controls the expression of CYP1A1/1A2 and CYP1B1, was detected in cytosolic fractions from these tissues as a 104 kDa and a minor level of the 106 kDa form. These are potentially very important findings in light of the role of CYP1A1/1A2 and CYP1B1 in activation of polyaromatic hydrocarbons, heterocyclic amines and nitroaromatic hydrocarbons to genotoxic metabolites, and the health consequences of these metabolites on humans, as consumers of goat milk and meat. Using polyclonal antibodies against rat hepatic CYP2B1 and CYP3A1, the goat CYP2B and CYP3A forms were not detectable in livers of goats at any age, but lungs of adult and 6 week old goats expressed these two CYPs in levels equivalent to the livers of phenobarbital‐induced rats. On the other hand, anti‐rat CYP2C6 antibodies specifically detected two goat ortholog forms which were expressed in all three tissues and exhibited age‐dependent changes. In conclusion, results from both immunoblot and HPLC analyses confirmed that, as in other species, the expression of P450 isozymes in goat is under both developmental‐and tissue‐specific regulatory factors.
Pilocarpine Treatments Differentially Affect α2‐Adrenoceptors which Modulate the Firing Rate of Locus coeruleus Neurones and the Synthesis and Release of Noradrenaline in Rat Brain
Authors: Garro Mikel Asier , Pineda Joseba , Giralt Maria Teresa , Ugedo Luisa
Published: March 2009

Abstract:We have investigated the effect of treatments with the muscarinic acetylcholine receptor agonist, pilocarpine, on the sensitivity of central α2‐adrenoceptors that regulate the firing activity of rat locus coeruleus, the tyrosine hydroxylase activity in the rat cortex, hippocampus and hypothalamus, and the K+‐evoked release of [3H]noradrenaline from rat cortical and hippocampal synaptosomes. Short‐term (4 days), but not acute, treatment with pilocarpine caused a small but statistically significant increase in the inhibitory effect of the α2‐adrenoceptor agonist clonidine on the firing rate of locus coeruleus neurones, with a decrease in the ED50of 29% (P<0.001). However, no change in the effect of clonidine on the locus coeruleus was observed after longer pilocarpine (11 days) treatment. In the rat cerebral cortex, but not in hippocampus or hypothalamus, chronic (19 days) treatment with pilocarpine caused a decrease in the inhibitory effect of clonidine on tyrosine hydroxylase activity (55%, P<0.05), but did not change the stimulatory effect of the α2‐adrenoceptor antagonist idazoxan. Moreover, treatments (4, 11 and 19 days) with pilocarpine did not alter the inhibitory effect of clonidine [10−8‐10−5M] on the K+‐evoked release of [3H]noradrenaline from rat cortical and hippocampal synaptosomes. These results indicate that administration of pilocarpine slightly potentiates some but not all the functional responses mediated by brain presynaptic α2‐adrenoceptors. In conclusion, these results do not support the hypothesis that chronic treatments with pilocarpine lead to a suitable model of α2‐adrenoceptor supersensitivity.
Vasodilator Action of the Nitroxylated Cyanoamidine Derivative, KRN2391, in Rabbit Basilar Artery
Authors: Ryman Torsten , Petersson Jesper , Högestätt Edward D.
Published: March 2009

Abstract: KRN2391 is a cyanoamidine derivative with a pyridine ring and a nitroxyl group. This gives the molecule a dual pharmacological action as both an ATP‐sensitive K channel (KATP) opener and an organic nitrate. In cerebrovascular disease with endothelial dysfunction, such a compound could be advantageous to prevent the negative consequences of a reduced synthesis of endogenous nitric oxide and endothelium‐derived hyperpolarizing factor. The objective of this study was to characterise the vasodilator action of KRN2391 in a cerebral artery. As shown in the rabbit basilar artery contracted by endothelin‐1 KRN2391 elicited a concentration‐dependent relaxation. KRN2391 was unable to relax arteries contracted by a 60 mM K solution. The KRN2391‐induced relaxation of endothelin‐1‐contracted arteries was unaffected by NG‐nitro‐L‐arginine (0.1 mM), indomethacin (10 μM) or removal of the endothelium. The guanylate cyclase inhibitors ODQ (10 μM) and LY53583 (10 μM), and the cGMP phosphodiesterase inhibitor zaprinast (10 μM) each had no effect on the KRN2391‐induced relaxation. Glibenclamide (1 μM), a blocker of KATP, caused a rightward shift of the concentration‐response curve for KRN2391. The relaxation induced by the prototype KATP opener levcromakalim was inhibited to a similar extent by glibenclamide. Addition of ODQ or LY53583, or the calcium‐sensitive K channel blockers apamin (0.1 μM) and charybdotoxin (0.1 μM) in the presence of glibenclamide did not produce a significant further inhibition of the KRN‐induced relaxation. KRN2391 (10 μM) did not influence the content of cGMP in the basilar artery, whereas the nitric oxide donor 3‐morpholino‐sydnonimine (0.1 mM) increased the cGMP level three‐fold. Thus, KRN2391 is an effective vasodilator of the rabbit basilar artery, acting mainly through opening of KATP. The nitro‐moiety of the molecule does not seem to contribute to the relaxant effect in this artery.