bluuebunny/crossref_metadata_2025_split huggingface dataset:
Silicon isotopes in Antarctic sponges: an interlaboratory comparison
Authors: Hendry Katharine R. , Leng Melanie J. , Robinson Laura F. , Sloane Hilary J. , Blusztjan Jerzy , Rickaby Rosalind E.M. , Georg R. Bastian , Halliday Alex N. 
Published: August 2010

AbstractCycling of deepwater silicon (Si) within the Southern Ocean, and its transport into other ocean basins, may be an important player in the uptake of atmospheric carbon, and global climate. Recent work has shown that the Si isotope (denoted by δ29Si or δ30Si) composition of deep sea sponges reflects the availability of dissolved Si during growth, and is a potential proxy for past deep and intermediate water silicic acid concentrations. As with any geochemical tool, it is essential to ensure analytical precision and accuracy, and consistency between methodologies and laboratories. Analytical bias may exist between laboratories, and sponge material may have matrix effects leading to offsets between samples and standards. Here, we report an interlaboratory evaluation of Si isotopes in Antarctic and sub-Antarctic sponges. We review independent methods for measuring Si isotopes in sponge spicules. Our results show that separate subsamples of non-homogenized sponges measured by three methods yield isotopic values within analytical error for over 80% of specimens. The relationship between δ29Si and δ30Si in sponges is consistent with kinetic fractionation during biomineralization. Sponge Si isotope analyses show potential as palaeoceaongraphic archives, and we suggest Southern Ocean sponge material would form a useful additional reference standard for future spicule analyses.
Biology of the Antarctic dragonfishVomeridens infuscipinnis(Notothenioidei: Bathydraconidae)
Authors: Kuhn Kristen L. , Near Thomas J. , Detrich H. William , Eastman Joseph T. 
Published: August 2010

AbstractNineteen specimens of the rare dragonfishVomeridens infuscipinniswere evaluated for meristic counts, morphometric measurements, vomerine teeth and the supratemporal canal, anatomical and histological observations of bone, cartilage and lipid, diet, and reproductive status. Seven individuals were measured for buoyancy. All specimens had small vomerine teeth that varied in number. There was also variability in the arrangement of the supratemporal pores and canals.Vomeridenspossess a body with little bone and considerable amounts of cartilage and lipid. A mean percentage buoyancy of 1.61% indicated thatVomeridensis nearly neutrally buoyant. Inferences from measurements of buoyancy and from morphological data suggest thatVomeridenslives in an epibenthic water column habitat at 400–900 m. Facilitated by its reduced body density,Vomeridensare likely to forage in the water column by hovering above the substrate. The stomach contents consisted of krill (Euphausia superba), some as large as 46–50 mm.The absolute and relative fecundity in seven female was 1576–2296 oocytes (mean 1889) and 21.3–28.9 oocytes g-1body weight (mean 25.3), respectively. The reproductive effort in terms of egg diameter, GSI, and absolute and relative fecundity is similar to that for other bathydraconids.
Incorporating zero and missing responses into CVM with open-ended bidding: willingness to pay for blue skies in Beijing
Authors: YU XIAOHUA , ABLER DAVID 
Published: August 2010

ABSTRACTBased on decision theory, this paper suggests a four-hurdle model to deal with zero and missing responses in the contingent valuation method with open-ended bidding, which is used to analyze the willingness to pay for blue skies in Beijing where air pollution is known to be very serious. The mean and the median of the predicted willingness to pay for blue skies per household are, respectively, 120.15 and 128.60 yuan, less than 0.2% of the per capita annual disposal income in Beijing. This is very low compared to results from studies of other countries. The empirical results also indicate that the four-hurdle model is superior to the Tobit model and raw data estimation.
Paraquat‐Induced Membrane Dysfunction in Pulmonary Microvascular Endothelial Cells
Authors: Tsukamoto Maki , Tampo Yoshiko , Sawada Minoru , Yonaha Masanori 
Published: August 2010

Abstract:Membrane dysfunction monitored by lactate dehydrogenase release from cultured pulmonary microvascular endothelial cells of pigs, which were exposed to paraquat at different concentrations (0.1–2 mM), was examined. Paraquat caused a time‐dependent increase in lactate dehydrogenase release. Lactate dehydrogenase releases after 72 hr, 32, 58, and 84% by 0.1, 0.5, and 2 mM paraquat, respectively, were well correlated with cell viability measured by cell adherence. In contrast, reductions of two tetrazolium compounds were depleted profoundly by 72 hr after exposure to 0.5 mM paraquat, suggesting depletion of intracellular reductive substances. Extracellular hydrogen peroxide began to significantly increase 56 hr or 32 hr after exposure to 0.5 mM or 1.5 mM paraquat, respectively, preceding the initial increase of lactate dehydrogenase release (64 hr by 0.5 mM or 48 hr by 1.5 mM). Lactate dehydrogenase release 72 hr after exposure to 0.5 mM paraquat was prevented strongly by catalase (1000 units/ml), but weakly by superoxide dismutase (1000 units/ml). These enzymes failed to restore the reduced acid phosphatase activity. Also, 0.1 mM desferal or α,α′‐dipyridyl protected lactate dehydrogenase release. Similarly, 1 mM thiourea or dimethylthiourea, and 0.5 mM α‐tocopherol or trolox, were effective, but diethylenetriaminepentaacetic acid (0.1 mM) and probucol (5 or 10 μM) were ineffective. Exposure of 0.5 or 1.5 mM paraquat suppressed levels of lipid peroxidation. These results indicate that membrane dysfunction by paraquat is ascribed to an iron‐catalyzed reaction of extracellularly increased hydrogen peroxide. A deleterious species for the membrane dysfunction is discussed.
The Preservatives Ethyl‐, Propyl‐ and Butylparaben are Oestrogenic in an in vivo Fish Assay
Authors: Pedersen Knud L. , Pedersen Søren N. , Christiansen Lisette B. , Korsgaard Bodil , Bjerregaard Poul 
Published: August 2010

Abstract:The widely used phenolic preservatives ethylparaben, propylparaben, butylparaben and their common metabolite p‐hydroxybenzoic acid were tested for their ability to evoke an oestrogenic response in vivo. Yolk protein induction in sexually immature rainbow trout was used as an oestrogen‐specific endpoint after repeated injections of the compounds. All tested parabens were oestrogenic in doses between 100 and 300 mg/kg, while the metabolite showed no activity. Ethylparaben was found to be approximately sixty times weaker than propyl‐ and butylparaben which had oestrogenic potencies comparable to those previously found for bisphenol A.
Minimal Toxicity to Myeloid Progenitor Cells of Weekly24‐Hr Infusion of High‐Dose 5‐Fluorouracil: Direct Evidence from Colony Forming Unit‐Granulocyte andMonocyte (CFU‐GM) Clonogenic Assay
Authors: Yeh Kun‐Huei , Yeh Shiou‐Hwei , Chang Yu‐Shiahn , Cheng Ann‐Lii 
Published: August 2010

Abstract:Although very high doses of 5‐fluorouracil was used in the weekly 24‐h infusion, high‐dose 5‐fluorouracil (2600 mg/m2/week) and leucovorin (500 mg/m2/week) protocol, myelosuppression was surprisingly low. The current study was conducted to investigate the possible mechanism underlying the low myelosuppression. To mimic the clinical situation, peripheral blood progenitor cells collected from 12 patients were used for colony forming unit‐granulocyte and monocyte clonogenic assay; and 2 representative modes of 5‐fluorouracil exposure (30 min. versus 24 hr) were examined for cytotoxic effects on human myeloid progenitor cells. Previous pharmacokinetic studies have estimated the concentrations of 5‐fluorouracil in the bone marrow to be 200–400 μM and 1–2 μM for the 30 min. infusion (600–900 mg/m2) and the 24 hr‐infusion (1000–2000 mg/m2) regimens, respectively. The results of our colony‐forming unit‐granulocyte and monocyte clonogenic assay showed that 24‐hr exposure to 5‐fluorouracil (2 μM) and 30 min. exposure to 5‐fluorouracil (100 μM) resulted in 27.2% and 78.2% inhibition of the colony formation, respectively. Our data provided direct evidence which may explain why myelotoxicity is significantly less in weekly 24 hr infusion of fluorouracil than in the conventional bolus regimens.
Antioxidative and Prooxidative Action of Stilbene Derivatives
Authors: Miura Toshiaki , Muraoka Sanae , Ikeda Nahoko , Watanabe Miki , Fujimoto Yukio 
Published: August 2010

Abstract:The effects of stilbene derivatives, including resveratrol, diethylstilboestrol and stilbene, as antioxidants or prooxidants were examined. Resveratrol and diethylstilboestrol, but not stilbene, strongly inhibited NADPH‐ and adenosine 5′‐diphosphate (ADP)‐Fe3+‐dependent lipid peroxidation at the initial and propagation stages. In addition, phenolic stilbenes also inhibited ultraviolet light‐induced lipid peroxidation. Resveratrol and diethylstilboestrol efficiently scavenged 2,2′‐azobis‐(2‐amidinopropane)‐dihydrochloride peroxyl radicals. However, 2,2′‐diphenyl‐p‐picrylhydrazyl radicals were trapped only by resveratrol, but not by diethylstilboestrol. These results suggest that the inhibitory effect of phenolic stilbenes on lipid peroxidation was due to their scavenging ability of lipid peroxyl and/or carbon‐cantered radicals. Resveratrol efficiently reduced ADP‐Fe3+, but not EDTA‐Fe3+. Stilbenes and diethylstilboestrol did not reduce either ADP‐Fe3+ or EDTA‐Fe3+. The strand breaks of DNA were stimulated during the interaction of resveratrol with ADP‐Fe3+ in the presence of H2O2. These results suggest that phenolic stilbenes act as antioxidants of membrane lipids and that resveratrol has a prooxidative effect DNA damage during interaction with ADP‐Fe3+ in the presence of H2O2.
Selegiline Metabolism and Cytochrome P450 Enzymes:In vitro Study in Human Liver Microsomes*
Authors: Taavitsainen Päivi , Anttila Markku , Nyman Leena , Karnani Hari , Salonen Jarmo S. , Pelkonen Olavi 
Published: August 2010

Abstract:Although being a drug therapeutically used for a long time, the enzymatic metabolism of selegiline has not been adequately studied. In the current work we have studied the cytochrome P450 (CYP)‐catalyzed oxidative metabolism of selegiline to desmethylselegiline and l‐methamphetamine and the effects of selegiline, desmethylselegiline and l‐methamphetamine on hepatic CYP enzymes in human liver microsomes in vitro. The apparent Km values for desmethylselegiline and l‐methamphetamine formation were on an average 149 μM and 293 μM, and the apparent Vmax values, 243 pmol/min./mg and 1351 pmol/min./mg, respectively. Furafylline and ketoconazole, the known reference inhibitors for CYP1A2 and CYP3A4, respectively, inhibited the formation of desmethylselegiline with Ki value of 1.7 μM and 15 μM. Ketoconazole inhibited also the formation of l‐methamphetamine with Ki of 18 μM. Fluvoxamine, an inhibitor of CYP1A2, CYP2C19 and CYP3A4, inhibited the formation of desmethylselegiline and l‐methamphetamine with Ki values of 9 and 25 μM, respectively. On the basis of these results we suggest that CYP1A2 and CYP3A4 contribute to the formation of desmethylselegiline and that CYP3A4 participates in the formation of l‐methamphetamine. In studies with CYP‐specific model activities, both selegiline and desmethylselegiline inhibited the CYP2C19‐mediated S‐mephenytoin 4′‐hydroxylation with average IC50 values of 21 μM and 26 μM, respectively. The Ki for selegiline was determined to be around 7 μM. Selegiline inhibited CYP1A2‐mediated ethoxyresorufin O‐deethylation with a Ki value of 76 μM. Inhibitory potencies of selegiline, desmethylselegiline and l‐methamphetamine towards other CYP‐model activities were much lower. On this basis, selegiline and desmethylselegiline were shown to have a relatively high affinity for CYP2C19, but no evidence about selegiline metabolism by CYP2C19 was obtained.
Hydrolytic and Metabolic Characteristics of the Esters of1‐(3′‐Hydroxypropyl)‐2‐methyl‐3‐hydroxypyridin‐4‐one (CP41), Potentially Useful Iron Chelators
Authors: Liu Ding Y. , Liu Zu D. , Lu Shu L. , Hider Robert C. 
Published: August 2010

Abstract:1‐(3′‐Hydroxypropyl)‐2‐methyl‐3‐hydroxypyridin‐4‐one (CP41) has been extensively investigated as an orally effective iron chelator. In order to improve the pharmacokinetic and metabolic properties of CP41, eleven aromatic esters have been synthesised and tested as potential prodrugs. In the present study, the hydrolytic rates of these CP41 esters in phosphate buffer (pH2.0 and pH7.4), rat blood and rat liver homogenate have been determined and found to cover a wide range. Generally, they possessed relatively slow hydrolytic rates in phosphate buffer (0–50 nmol/ml/hr at pH 2.0 and 0–140 nmol/ml/hr at pH 7.4). The hydrolytic rates in rat blood fell in the range of 9–5766 nmol/ml blood/hr and in rat liver homogenate 1–800 μmol/g liver tissue/hr. All esters possess a higher lipophilicity than that of the parent compound CP41. Although no apparent relationship was observed between the lipophilicities and hydrolytic rates, the esters with relatively higher hydrolytic rates in liver homogenate tend to possess higher iron scavenging efficacies. Further investigation of the metabolism of selected CP41 esters indicates that metabolism is a key factor influencing the efficacy of CP41 esters, as some esters can be metabolically inactivated in the liver in preference to undergoing ester hydrolysis. Ester design, combined with a knowledge of the prodrug metabolism, is a useful strategy for the production of 3‐hydroxypyridin‐4‐ones with enhanced iron scavenging efficacy.
The Effect of Glutathione Modulation on the Concentration of Homocysteine in Plasma of Rats
Authors: Øvrebø Kjell K. , Svardal Asbjørn 
Published: August 2010

Abstract:Elevated plasma homocysteine concentration in humans is associated with increased risk of arteriosclerosis and ischaemic heart disease. We studied whether the plasma homocysteine concentration could be changed by administration of drugs that modulate the concentration of glutathione in both plasma and tissue. Male wistar rats received reduced glutathione (0.5 mmol/kg), N‐acetylcysteine (0.5 mmol/kg), L‐buthionine‐[S,R]‐sulfoximine (2 mmol/kg) or Ringer acetate intravenously. Twenty min. later an arterial blood sample was drawn for the measurement of homocysteine and other thiols in the plasma. The thiols were quantified by reversed‐phase ion‐pair liquid chromatography and fluorescence detection. The total homocysteine concentration in plasma of fasted rats was 6.1±0.5 μM. Intravenous administration of reduced glutathione or N‐acetylcysteine reduced the homocysteine concentration in plasma significantly by 51% to 3.0±0.3 μM and 63% to 2.2±0.2 μM, respectively (P<0.05). In contrast, L‐buthionine‐[S,R]‐sulfoximine increased the concentration of homocysteine by 41% to 8.6±0.6 μM (P<0.05). The glutathione concentration in plasma was 19.5±1.9 μM in controls and was unchanged by N‐acetylcysteine administration. Reduced glutathione increased plasma glutathione to 379.7±22.9 μM (P<0.05), whereas L‐buthionine‐[S R]‐sulfoximine lowered the plasma glutathione concentration to 5.3±0.4 μM. Homocysteine was negatively correlated to the glutathione (r=−0.399, P<0.01) and the cysteine (r=−0.52, P<0.01) concentrations in plasma. Our conclusion is that modulation of the glutathione levels influences the concentration of homocysteine in plasma of rats.
Progesterone and Testosterone Modulate the Convulsant Actions of Pentylenetetrazol and Strychnine in Mice
Authors: Pesce María Ester , Acevedo Ximena , Bustamante Diego , Miranda Hugo F. , Pinardi Gianni 
Published: August 2010

Abstract:The influence of progesterone and testosterone on the incidence of seizures after administration of intraperitoneal pentylenetetrazol and subcutaneous strychnine was evaluated in mice. Pentylenetetrazol and strychnine were administered in doses that induced seizures in 40–50% of control mice in dioestrus (48 and 0.9 mg/kg, respectively). The percentage of seizures induced by pentylenetetrazol and strychnine was significantly lower in female mice in prooestrus/oestrus, when progesterone levels are high, than in dioestrus, when progesterone levels are low. Pretreatment of pentylenetetrazol‐challenged mice with progesterone (250 μg/kg) increased the incidence of seizures in prooestrus/oestrus, without affecting seizures in dioestrus. The same pretreatment in strychnine‐challenged mice also increased the incidence of seizures in prooestrus‐dioestrus, but significantly reduced the incidence of seizures in dioestrus. In addition, progesterone pretreatment significantly increased the percentage of deaths induced by strychnine in prooestrus‐oestrus, reducing deaths in dioestrus. Orchidectomized male mice had a significantly higher incidence of seizures after administration of pentylenetetrazol and strychnine than control mice. Administration of 11 daily doses of 250 μg/kg of testosterone to castrated mice significantly reduced the incidence of seizures induced by pentylenetetrazol. These results confirm the modulatory influence of reproductive steroids on the excitability of the central nervous system and the possible clinical importance of progesterone and testosterone in the management of partial epilepsy.
Doses and Time‐Dependent Effects of 3′‐Azido‐3′‐deoxythymidine on T47D Human Breast Cancer Cells in vitro
Authors: Mediavilla María D. , Sánchez‐Barceló Emilio J. 
Published: August 2010

Abstract:The objective of the present work was to study the effects of 3′‐azido‐3′‐deoxythymidine (azidothymidine, Zidovudine®) on human breast cancer cells by using, as a model, the T47D cell line (typified as oestrogen‐dependent and p53‐mutated). Low azidothymidine doses (3.125 μM) increase the percentage of cells in S‐phase, with the effect reversing after 24 hr of incubation; as azidothymidine doses increase, the magnitude and duration of its effect increase proportionally, although, even with the highest concentrations (50–100 μM) the effects decline after 48 hr of incubation. If media (containing azidothymidine or vehicle) are daily renewed, the azidothymidine effects (accumulation of cells in S‐phase) are higher and decline later than when media and drug are not changed during the whole culture period, thereby suggesting that the reversion of azidothymidine effects could be related with a degradation of the drug or accumulation in media of substances which counteract its effects. Azidothymidine inhibits T47D cell proliferation at concentrations higher than 50 μM. The exposure to 50 or 100 μM azidothymidine induced cell apoptosis after 48 hr or more of incubation. We conclude that: a) azidothymidine, with appropriate doses and duration of treatment, synchronizes cells in S‐phase, inhibits proliferation, and induces apoptosis, b) the discontinuous application of the drug rather than continuous exposure to it increases its efficiency to synchronize the T47D cell cycle. This in vitro anti‐breast cancer activity suggests that a possible clinical usefulness of azidothymidine, either alone or associated with other drugs with cycle‐specific antitumoural activity circumscribed to the S‐phase of cell cycle, is worthy of investigation.
Increase in Blood Pressure with Enhanced Na+, K+‐ATPase Activity in Stroke‐Prone Spontaneously Hypertensive Rats after 4‐Weeks Intake of Rapeseed Oil as the Sole Dietary Fat
Authors: Naito Yukiko , Konishi Chika , Katsumura Hideo , Ohara Naoki 
Published: August 2010

Abstract:Twenty stroke‐prone spontaneously hypertensive rats were divided into 2 groups of 10 animals each, and fed a defatted diet and orally administered rapeseed (canola) oil or soybean oil at 10 (w/w)% of the consumed diet once a day for 4 weeks. At the 4th week of administration, the systolic blood pressure in the canola oil group was higher (235±2 mmHg, mean±S.E.M., N=10) than that in the soybean oil group (225±4 mmHg, N=10, P<0.05). In isolated, perfused mesenteric bed from these rats, the increase in perfusion pressure by norepinephrine, ATP, arachidonic acid, endothelin‐1, angiotensin II or serotonin showed no between‐group differences. There were also no between‐group differences in the production of thromboxane A2 and prostaglandin I2 in the outflow by arachidonic acid injection. On the other hand, in the isolated aortic ring from the canola oil group, developed tension in potassium‐free solution was enhanced with activation of Na+, K+‐ATPase. These results suggest that canola oil intake as the sole dietary fat increases systolic blood pressure of stroke‐prone spontaneously hypertensive rats. The changes in vascular responsiveness to vasoconstrictors and production of prostanoids are unlikely to have relevance to the elevation of blood pressure. However, altered Na+, K+‐ATPase activity may play a role in the promotion of blood pressure elevation.
Mobilisation of Cadmium by meso‐ and racemic‐2,3‐Dimercaptosuccinic Acid (DMSA) in Rats
Authors: Blanuša Maja , Kostial Krista , Restek‐Samaržija Nada , Piasek Martina , Jones Mark M. , Singh Pramod K. 
Published: August 2010

Abstract:A higher efficiency of cadmium binding with racemic than with meso‐2,3‐dimercaptosuccinic acid (rac‐DMSA; meso‐DMSA) was found in an in vitro speciation model by Fang et al. (1996). This finding has not yet been tested in vivo. This paper presents results on mobilisation of cadmium by meso‐ and rac‐DMSA in rats. Cadmium chloride was administered as the radioactive isotope 109Cd intraperitoneally to all animals. One group was an untreated control and two groups were treated with meso‐ and rac‐DMSA, respectively. Treatment with chelators was applied twice, immediately after 109Cd and 24 hr afterwards intraperitoneally at the dose of 1 mmol/kg, each. Six days later radioactivity was measured in the liver and kidneys. Whole‐body counting was carried out on days 1, 2, 3 and 6 of the experiment. At the end of the experiment, both treatments caused a decrease in 109Cd whole‐body retention with rac‐DMSA being more efficient (decrease from 83% in control to 74% and 64% in groups treated with meso‐ and rac‐DMSA, respectively). The same reduction of 109Cd was obtained by both chelators in the liver (from 57% to about 47%). In the kidney only rac‐DMSA produced significant reduction of 109Cd (from 5.3% to 3.5%). In conclusion, these results show modest reduction of cadmium in the body by two isoforms of DMSA with rac‐DMSA being slightly more efficient than meso‐DMSA.
Blood Concentration and Toxicity of the Antimetastasis Agent NAMI‐A Following Repeated Intravenous Treatment in Mice
Authors: Cocchietto Moreno , Sava Gianni 
Published: August 2010

Abstract:NAMI‐A is a new generation antitumour ruthenium‐based agent and characterised by strong efficacy against lung metastases of experimental solid tumours in mice. The effects of intravenous administration of 15, 35 and 50 mg/kg/day of NAMI‐A for 5 consecutive days on blood concentration and host toxicity were tested on Swiss CD1 male and female mice. The blood concentration of NAMI‐A, both after the first injection and at the end of the 5‐day treatment fell rapidly and 5 min. after the last injection it was always below 10% of the administered dose. Kinetic parameters, calculated at the end of the 5‐day treatment cycle according to a mono‐compartment model (fitting with R2=0.9), indicate a t1/2 of about 18 hr. Toxicity i) was observed only at the highest dose used (50 mg/kg/day), ii) was greater in females than in males, iii) in mice which survived treatment was completely reversed within 3‐weeks of the end of the treatment. Haematological examinations, clinical chemistry data and histopathologic studies were consistent in terms of the effect on host lymphoid tissues, consisting in spleen and lymph node depletion and in a general increase of circulating leukocytes. Data on ruthenium organ retention confirm lack of brain penetration and a relatively high lung concentration which might account for the remarkable effect on lung metastases.