Dexmedetomidine inhibits muscarinic type 3 receptors expressed in <Emphasis Type="Italic">Xenopus</Emphasis> oocytes and muscarine-induced intracellular Ca<Superscript>2+</Superscript> elevation in cultured rat dorsal root ganglia cells

Dexmedetomidine, an α₂-adrenoceptor agonist, has been approved for clinical use, although the mechanism of dexmedetomidine action has not been fully elucidated. Several studies have shown that G protein-coupled receptors (GPCRs) are recognized as targets for anesthetics and analgesics. Therefore, it is of interest to determine whether dexmedetomidine affects the function of GPCRs other than the α₂-adrenoceptor. We examined the effects of dexmedetomidine on M₁, M₃, 5-HT_2C, substance P, and orexin 1 receptors in Xenopus oocytes expressing individual receptors. In addition, we investigated the effects of dexmedetomidine on muscarinic receptor-mediated changes in [Ca²⁺]_i in the dorsal root ganglia (DRG) of 3-week-old Wister rats. Dexmedetomidine did not affect the 5-HT_2C-, or substance P-induced Cl⁻ currents and had little inhibition on the orexin A-induced current in oocytes expressing the respective receptors. The compound also had little effect on the acetylcholine (ACh, 1 μM)-induced Ca²⁺-activated Cl⁻ currents in Xenopus oocytes expressing M₁ receptors. In contrast, dexmedetomidine inhibited the ACh-induced currents in Xenopus oocytes expressing M₃ receptors; 1 nM, 10 nM, 100 nM, and 1 μM dexmedetomidine reduced the current to 66.5 ± 4.8, 51.3 ± 12, 34.6 ± 11, and 26.8 ± 6.4% of the control value, respectively (EC₅₀ = 3.5 ± 0.7 nM). Dexmedetomidine reduced the ACh-induced Cl⁻ currents after treatment with the selective protein kinase C inhibitor GF109203X. Moreover, the compound inhibited the muscarinic receptor-mediated increases in [Ca²⁺]_i in cultured DRG cells in a concentration-dependent manner. Dexmedetomidine inhibits the function of M₃ receptors, in addition to its agonistic effects on α₂-adrenoceptors, which provides further insight into the pharmacological properties of dexmedetomidine.     

Sub-lethal effects of acetone on <Emphasis Type="Italic">Daphnia magna</Emphasis>

There is increasing concern about the sub-lethal effect of hydrophobic chemicals in the water medium. Even though acetone is a commonly used solvent in toxicity testing, few studies have focussed on its chronic toxicity to Daphnia magna and the available results are often contradictory. In this study, acetone was tested on D. magna in a 21-day exposure experiment and the effects on mortality, fertility and morphology of exposed organisms (F₀) and offspring (F₁–F₂, reared without acetone) were evaluated. No significant reduction of survival was observed with increasing concentrations, and no significant reduction in fecundity in any treatment group in terms of average number of daphnids per mother was observed. Abnormal development of second antennae was observed on F₁ from F₀ exposed to 79 mg l⁻¹ solvent. The ET50 of acetone on the number of mothers that produced deformed offspring over time was 12.5 days. Our results suggest that the acetone concentration should not exceed 7.9 mg l⁻¹, which is 10 times less than the allowed concentration as determined by OECD chronic assays on D. magna. More attention should be paid to small, water-soluble molecules usually considered of low concern for chronic toxicity because they might affect other metabolic pathways.     

Change in life cycle parameters and feeding rate of <Emphasis Type="Italic">Ceriodaphnia silvestrii</Emphasis> Daday (Crustacea,Cladocera) exposure to dietary copper

Changes in life cycle parameters (survival, growth, reproduction) and feeding rate of the tropical cladoceran Ceriodaphnia silvestrii as affected by Cu contaminated algae Pseudokirchneriella subcapitata were investigated. The dietary copper exposure ranged from 3 × 10⁻¹⁵ to 68 × 10⁻¹⁵ g Cu algal cell⁻¹. Low waterborne copper exposure (around 10⁻¹⁰ mol l⁻¹ free Cu²⁺ ions) was kept in the experiments. The results show an increasing toxic effect on C. silvestrii with copper increase in algal cells; at the highest copper exposure, all life cycle parameters were significantly affected. A concentration of 38 × 10⁻¹⁵ g Cu algal cell⁻¹ reduced egg hatching percentile and the number of neonates produced per female, but did not cause any statistically significant effect on animals survival nor to the number of eggs produced per female. The following sequence of events was observed from the lowest to the highest copper contamination: reproduction, feeding rate, body length and, at last, survival was affected. We conclude that algal cells are an important route of copper exposure and toxicity to cladocerans.     

Subcellular/tissue distribution and responses to oil exposure of the cytochrome P450-dependent monooxygenase system and glutathione S-transferase in freshwater prawns (Macrobrachium malcolmsonii, M. lamarrei lamarrei)

Subcellular fractions (mitochondrial, cytosolic and microsomal) prepared from the tissues (hepatopancreas, muscle and gill) of freshwater prawns Macrobrachium malcolmsonii and Macrobrachium lamarrei lamarrei were scrutinized to investigate the presence of mixed function oxygenase (MFO) and conjugating enzymes (glutathione-S-transferase, GST). Cytochrome P450 (CYP) and other components (cytochrome b₅; NADPH-cytochrome c (CYP) reductase and NADH-cytochrome c-reductase activities) of the MFO system were predominantly present in the hepatic microsomal fraction of M. malcolmsonii and M. lamarrei lamarrei. The results are in agreement with the notion that monooxygenase system is mainly membrane bound in the endoplasmic reticulum, and that the hepatopancreas is the major metabolic tissue for production of biotransformation enzymes in crustaceans. Further, the prawns were exposed to two sublethal (0.9 ppt (parts per thousand) and 2.3 ppt) concentrations of oil effluent. At the end of 30th day, hydrocarbons and detoxifying enzymes were analysed in the hepatopancreas. The accumulations of hydrocarbon in the tissues gradually increased when exposed to sublethal concentrations of oil effluent and were associated with significantly enhanced levels of cytochrome P450 (180.6±6.34 pmol mg⁻¹ protein (P<0.05 versus control, 136.5±7.1 pmol mg⁻¹ protein) for 2.3 ppt and 305.6±8.5 pmol mg⁻¹ protein (P<0.001 versus control, 132.3±6.8 pmol mg⁻¹ protein] for 0.9 ppt of oil exposed M. malcolmsonii; 150±6.5 pmol mg⁻¹ protein (P<0.01 versus control, 84.6±5.2 pmol mg⁻¹ protein) for 2.3 ppt and 175±5.5 pmol mg⁻¹ protein (P<0.01 versus control, 87.6±5.4 pmol mg⁻¹ protein) for 0.9 ppt of oil exposed M. lamarrei lamarrei), NADPH cytochrome c-reductase activity (14.7±0.6 nmol min⁻¹ mg⁻¹ protein (P<0.05 versus control, 6.8±0.55 nmol min⁻¹ mg⁻¹ protein) for 2.3 ppt and 12.1±0.45 nmol min⁻¹ mg⁻¹ protein (P<0.01 versus control, 6.9±0.42 nmol min⁻¹ mg⁻¹ protein) for 0.9 ppt of oil exposed M. malcolmsonii; 12.5±0.31 nmol min⁻¹ mg⁻¹ protein (P<0.001 versus control, 4.6±0.45 nmol min⁻¹ mg⁻¹ protein) for 2.3 ppt and 9.6±0.32 nmol min⁻¹ mg⁻¹ protein (P<0.01 versus control, 4.9±0.41 nmol min⁻¹ mg⁻¹ protein) for 0.9 ppt of oil exposed M. lamarrei lamarrei) and cytochrome b₅ (124.8±3.73 pmol mg⁻¹ protein (P<0.01 versus control, 76.8±4.2 pmol mg⁻¹ protein) for 2.3 ppt and 115.3±3.86 pmol mg⁻¹ protein (P<0.01 versus control, 76.4±4.25 pmol mg⁻¹ protein) for 0.9 ppt of oil exposed M. malcolmsonii and 110±3.11 pmol mg⁻¹ protein (P<0.01 versus control, 63.7±3.24 pmol mg⁻¹ protein) for 2.3 ppt and 95.3±2.63 pmol mg⁻¹ protein (P<0.01 versus control, 61.4±2.82 pmol mg⁻¹ protein) for 0.9 ppt of oil exposed M. lamarrei lamarrei). The enhanced levels of biotransformation enzymes in oil-exposed prawns demonstrate a well-established detoxifying mechanism in crustaceans, and the response offers the possibility of use as a biomarker for the early detection of oil pollution.Special Issue on Biomarkers of Marine Pollution and Bioremediation     

Tolerance and accumulation of lead by species of <Emphasis Type="Italic">Iris</Emphasis> L.

Seedling development, accumulation and distribution of lead (Pb) in Iris lactea var. chinensis (Fisch.) Koidz. and I. tectorum Maxim. were studied using plants grown in sand culture and exposed to 0–10 mmol l⁻¹ concentrations of Pb supplied as Pb(NO₃)₂ for 28 days. A significant reduction in dry weight (dw) of shoots and roots of I. lactea var. chinensis was observed at 6 and 10 mmol l⁻¹, respectively, and a significant reduction in dw of shoots and roots of I. tectorum was observed at 6 mmol l⁻¹. Concentration of Pb in the shoots and roots of I. lacteal var. chinensis exposed to 4 mmol l⁻¹ Pb reached 1,109 μg g⁻¹ and 2,408 μg g⁻¹ dw, respectively. The index of tolerance (IT) of I. lactea var. chinensis among 0–8 mmol l⁻¹ Pb treatments were not significantly different, while those of I. tectorum at 6 mmol l⁻¹ Pb were significantly decreased. The results indicated that I. lactea var. chinensis was more tolerant to Pb than I. tectorum. Sub-cellular localization of Pb in root cells was evaluated using transmission electron microscopy (TEM) and Pb deposits were found along the plasma membrane of some root tip cells of I. lactea var. chinensis treated at 10 mmol l⁻¹ Pb. Deposits of Pd were also observed along the surface, in the root tip cell wall and in the cytoplasm of a few malformed cells of I. tectorum exposed at 10 mmol l⁻¹ Pb treatment. One possible mechanism to explain these observations may be that most cells can maintain normal activities in the plant by sacrificing a small number of cells that accumulate a large amount Pb and show toxicity. Future studies should be designed to test this hypothesis.     

Potential anthelmintics: polyphenols from the tea plant <Emphasis Type="Italic">Camellia sinensis</Emphasis> L. are lethally toxic to <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>

A novel gallate of tannin, (−)-epigallocatechin-(2β→O→7′,4β→8′)-epicatechin-3′-O-gallate (8), together with (−)-epicatechin-3-O-gallate (4), (−)-epigallocatechin (5), (−)-epigallocatechin-3-O-gallate (6), and (+)-gallocatechin-(4α→8′)-epigallocatechin (7), were isolated from the tea plant Camellia sinensis (L.) O. Kuntze var. sinensis (cv., Yabukita). The structure of 8, including stereochemistry, was elucidated by spectroscopic methods and hydrolysis. The compounds, along with commercially available pyrogallol (1), (+)-catechin (2), and (−)-epicatechin (3), were examined for toxicity towards egg-bearing adults of Caenorhabditis elegans. The anthelmintic mebendazole (9) was used as a positive control. Neither 2 nor 3 were toxic but the other compounds were toxic in the descending order 8, 7 ≈ 6, 9, 4, 5, 1. The LC₅₀ (96 h) values of 8 and 9 were evaluated as 49 and 334 μmol L⁻¹, respectively. These data show that many green tea polyphenols may be potential anthelmintics.     

Perylene Toxicity in the Estuarine Environment of Ria de Aveiro (Portugal)

Perylene, a 5-ring polycyclic aromatic hydrocarbon is common in estuarine sediments and its toxicity in the benthic and planktonic compartments is not yet clarified. The objectives of this work were: (1) to follow the toxicity of high concentrations of perylene (110 mg l⁻¹) on benthic bacteria and macrofauna (amphipod Corophium multisetosum); (2) to determine the effects of a low load of perylene (2 μg l⁻¹) on the metabolism of suspended bacteriobenthos after 9-day exposure, mimicking the effects of tidal erosion; (3) to contrast the effects of this low perylene load on the particle-free bacterioplankton and on the suspended and particle-adhered bacteriobenthos. No impact was detected in bacterial abundance exposed to 110 mg perylene l⁻¹ for 9 days. This concentration of perylene evoked no acute effects in C. multisetosum but, chronic toxicity assays revealed statistically significant negative effects on survival, growth and number of pregnant females. The bacterioplankton and the suspended bacteriobenthos, exposed to 2 μg perylene l⁻¹ during 2 weeks, responded with altered profiles of activity when compared to the control suspension. These values ranged, respectively, for bacterial biomass production from 134 to 210 and from 24 to 184 μg C l⁻¹ h⁻¹, for aminopeptidase from 1824 to 11,127 and from 1464 to 15,488 nmol l⁻¹ h⁻¹, and for β-glucosidase from 87 to 400 and from 57 to 1278 nmol l⁻¹ h⁻¹. The rate of oxygen consumption in the perylene-exposed suspension (0.04–2.85 mmol O₂ kg⁻¹ dw sed h⁻¹) exhibited a clearly distinct profile in relation to the control (0.57–1.60 mmol O₂ kg⁻¹ dw sed h⁻¹). The overall reactivity of the bacteriobenthos to perylene was interpreted as the result of toxic pressure followed by evolution of a diverse bacterial community.     

Evaluation of Some Pharmacological Activities of ethanol extracts of seeds, pericarp and leaves of Eugenia Jamolana in Rats

The present study investigated the effect of ethanol extracts of seeds, pericarp and leaves of Eugenia Jamolana (E. Jamolana) on inflammation, gastric ulcer, anti-oxidants and hepatoprotective in rats. The acute inflammation was induced by intra-plantar injection of carrageenan (100 μl of 1 %) in the rat hind paw. Gastric ulcer was evoked by indomethacin (25 mg/kg) oral administration. Liver damage was induced by given CCL₄ (2.5 ml/kg) orally. The median lethal (LD₅₀) of the ethanol extract of both seeds and pericarp were determined and revealed that the investigated extracts of seeds and pericarp were non toxic up to 5g/kg. The anti-inflammatory results showed that the oral administration of ethanol extract of E. Jamolana seeds (250,500 mg/kg) showed significant inhibition of oedema formation in dose-dependent manner by −27.86, −41.23, −44.73, −51.78 % and by −63.16, −37.77, −47.04, −55.36 % at 1, 2, 3 and 4 h at 1, 2, 3 and 4 h, respectively. While the pericarp given at dose (500 mg/kg) exhibited significant inhibition of the oedema formation by −34.64, −21,8, 19.23 and −33.47 % at 1, 2, 3 and 4 h, respectively post carrageenan injection as compared with saline control group. E. Jamolana leaves fraction 1 given orally at dose of 25 mg/kg, induced non significant change on oedema, while the oedema response was significantly inhibited by −25.14, −33.4, −20.57 and −26.46 % at 1, 2, 3 and 4 h, respectively in group of rats that received leaves fraction 2 at the same dose. Rats were given leaves fraction 3 extract showed inhibition of oedema formation by −4.48 % at 1^st h post- carrageenan injection, while at 2^nd, 3^rd and 4^th h showed non significant change on oedema formation. The acute gastric mucosal lesions was significantly reduced by given ethanol extract of E. Jamolana seeds, pericarp (250, 500 mg/kg) and leaves fractions 1, 2 and 3 (25 mg/kg) respectively in dose dependent manner, as compared with indomethacin treated group (control group). All tested extracts showed significant reduction in elevated serum ALT, AST and ALP levels as compared with CCl ₄ treated group. The ethanol extract of E. Jamolana seeds, pericarp and leaves fractions 1, 2, 3 showed significant elevation of blood GSH level and significant reduction in elevated plasma lipid peroxides (MDA) as compared with CCl₄ treated group. In conclusion we can see that the ethanol extracts of E. Jamolana of seeds, pericarp and leaves fractions showed anti-inflammatory, anti-ulcer, hepatoprotective and anti-oxidants activity. Received 15 June 2008; accepted 11 November 2008     

Cadmium tolerance and accumulation by two species of <Emphasis Type="Italic">Iris</Emphasis>

Seedlings of Iris lactea var. chinensis (Fisch.) Koidz. and I. tectorum Maxim. were subjected to 0–160 mg l⁻¹ Cd in hydroponic system and harvested after 42 days to determine effects on root and shoot dry mass. A subset of 16-day-old seedlings was exposed to 1000 mg l⁻¹ Cd to characterize sub-cellular localization of Cd in root cells. The Cd contents in the shoots of I. lactea var. chinensis reached 529 μg g⁻¹ dry weight (dw) at 80 mg l⁻¹ Cd treatment and in the shoots of I. tectorum reached 232 μg g⁻¹ dw at 40 mg l⁻¹ Cd treatment, without showing signs of visible toxicity. The Cd contents in the shoots of both two test species exceeded 100 μg g⁻¹, the critical value of Cd hyperaccumulator. The indices of tolerance (ITs) of I. lactea var. chinensis were higher than those of I. tectorum under 10–160 mg l⁻¹Cd stress. Sub-cellular localization of Cd in root cells was evaluated using transmission electron microscopy (TEM) and Cd deposits were found in the cell walls, in the cytoplasm and on the inner surface of xylem vessels in the root tip of I. lactea var. chinensis and I. tectorum. A few cells in the root tip of I. tectorum were necrotic. The results showed that the tolerance and accumulation of Cd by I. lactea var. chinensis were higher than those of I. tectorum, suggesting that I. lactea var. chinensis has potential application in phytoremediation.     

Effects of quipazine and m-chlorophenylbiguanide (m-CPBG) on temporal differentiation: evidence for the involvement of 5-HT2A but not 5-HT3 receptors in interval timing behaviour

Rationale Temporal differentiation refers to animals’ ability to regulate their behaviour during an ongoing interval. Striatal dopaminergic mechanisms are purported to be involved in temporal differentiation, and recent evidence also implicates 5-hydroxytryptaminergic (5-HTergic) mechanisms, possibly mediated by 5-HT_2A receptors. There is evidence that 5-HT₃ receptors contribute to the regulation of dopamine release in the basal ganglia; however, it is not known whether 5-HT₃ receptor stimulation can influence temporal differentiation. Objective We examined the effects of a selective 5-HT₃ receptor agonist m-CPBG, a mixed 5-HT_2A/3 receptor agonist quipazine, and selective 5-HT₃ and 5-HT_2A receptor antagonists (MDL-72222 and ketanserin, respectively) on temporal differentiation in a free-operant psychophysical procedure. Methods Twenty-four rats were trained to respond on two levers (A and B) under a free-operant psychophysical schedule, in which sucrose reinforcement (0.6 M, 50 μl) was provided intermittently for responding on A during the first half and on B during the second half of 50-s trials. Logistic psychometric functions were fitted to the relative response rate data [percent responding on B (%B) vs time from trial onset (t)], and quantitative indices of timing performance [T ₅₀ (value of t corresponding to %B=50), Weber fraction, and mean time of switching from A to B, S ₅₀] were derived. Results Quipazine (0.5, 1, and 2 mg kg⁻¹) altered timing performance, dose-dependently reducing T ₅₀ and S ₅₀; m-CPBG (2.5, 5, and 10 mg kg⁻¹) had no significant effect. The effect of quipazine was antagonized by ketanserin (2 mg kg⁻¹), but not by MDL-72222 (1 mg kg⁻¹). Conclusions The present results provide no evidence for the involvement of 5-HT₃ receptors in temporal differentiation and indicate that the effect of quipazine on performance was mediated by 5-HT_2A receptor stimulation. The results are consistent with previous evidence for the involvement of 5-HT_2A receptors in interval timing behaviour. Jonathan Francis Rickard (1977–2003), a gifted and dedicated PhD student, made a major contribution to this work.     

β-secretase (BACE1) inhibitors from <Emphasis Type="Italic">Perilla frutescens</Emphasis> var. <Emphasis Type="Italic">acuta</Emphasis>

In the course of screening for anti-dementia agents from natural products, two β-secretase (BACE1) inhibitors were isolated from the methanolic extract of Perilla frutescens var. acuta and identified as luteolin (1) and rosmarinic acid (2) with IC₅₀ values of 5.0×10⁻⁷ M and 2.1×10⁻⁵ M, respectively. They inhibited BACE1 in a non-competitive manner with a substrate in Dixon plots, suggesting that they might bind to either β-secretase subsite or to another regulatory site. Ki values of 1 and 2 were 6.2×10⁻⁵ M and 3.9×10⁻⁵ M, respectively. They were less inhibitory against other enzymes such as α-secretase (TACE), acetylcholine esterase (AchE), chymotrypsin, and elastase, indicating that they were relatively specific inhibitors of BACE1.     

Inhibition of growth and photosynthesis of selected green microalgae as tools to evaluate toxicity of dodecylethyldimethyl-ammonium bromide

The effect of dodecylethyldimethyl-ammonium bromide (DEAB), a quaternary ammonium, compound widely used as disinfectant, on phytoplankton of inland water systems was analysed by using an experimental model. A toxicity test was based on inhibition of photosynthesis performances (effective quantum yield from photosystem II, Φ_PSII and O₂ production) of the phytoplanktonic species Scenedesmus intermedius and Dictiosphaerium chlorelloides (Chlorophyceae) under growing doses of DEAB. A concentration-dependent toxic response was obtained in both parameters analysed. In addition, this response was almost immediate. Consequently, the measurement of both parameters (Φ_PSII and O₂ production) allows to assess DEAB toxicity with higher standards of precision and repeatability. We propose that this procedure could be used to detect presence of quaternary ammonium pollutants in freshwater.     

Isolation and identification of antioxidants from Pedilanthus tithymaloides

A bioassay-guided methodology utilizing 2,2-diphenyl-1-picrylhydrazyl (DPPH), the trolox equivalent antioxidant capacity (TEAC), and reducing power assays, as well as an assessment of scavenging properties against O₂^·−, H₂O₂, HOCl, ROO·, ·NO, and ONOO⁻ were used to find the main antioxidant principles of Pedilanthus tithymaloides (Euphorbiaceae), a shrub used in traditional Cuban medicine. The principles were identified as kaempferol 3-O-β-D-glucopyranoside-6′′-(3-hydroxy-3-methylglutarate), quercitrin, isoquercitrin, and scopoletin. The contents of total phenolics and flavonoids were found to be 76.0 ± 4.8 mg of gallic acid equivalents/g extract and 9.8 ± 0.4 mg of rutin equivalents/g extract, respectively.     

Lignan glycosides and flavonoids from <Emphasis Type="Italic">Saraca asoca</Emphasis> with antioxidant activity

Five lignan glycosides, lyoniside, nudiposide, 5-methoxy-9-β-xylopyranosyl-(−)-isolariciresinol, icariside E₃, and schizandriside, and three flavonoids, (−)-epicatechin, epiafzelechin-(4β→8)-epicatechin and procyanidin B₂, together with β-sitosterol glucoside, were isolated from a methyl alcohol (MeOH) extract of Saraca asoca dried bark. Their structures were determined by 1D and 2D nuclear magnetic resonance (NMR) and mass spectroscopic analysis. Antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay.     

Promotion of IL-8 production in PMA-stimulated HL-60 cells by sesquiterpene quinones from a marine sponge, <Emphasis Type="Italic">Hippospongia</Emphasis> sp.

An extract of a marine sponge, Hippospongia sp., collected in Palau has inhibitory activity against colony formation by Chinese hamster V79 cells. Bioassay-guided isolation gave eleven sesquiterpene quinones. Compounds 1–8 inhibited colony formation by V79 cells with EC₅₀ values between 0.6 and 2.8 μmol L⁻¹. Their effects on the production of an inflammatory cytokine, IL-8, in tetradecanoyl phorbol acetate (PMA)-stimulated HL-60 cells were also investigated, because IL-8 production is sometimes correlated with inhibition of cell growth. Ilimaquinone (1) and its 5 epimer (2) had similar activity against V79 cells (EC₅₀ = 2.8 and 2.3 μmol L⁻¹, respectively) but did not modulate IL-8 production even at 10 μmol L⁻¹. Smenospongidine (3) and its 5 epimer (4), smenospongiarine (5) and its 5 epimer (6), and smenospongine (7) and its 5-epimer (8), at 10 μmol L⁻¹, promoted IL-8 production. Compounds 3, 5, and 7 had slightly stronger activity against V79 cells (EC₅₀ = 0.6, 1.7, and 0.8 μmol L⁻¹, respectively) than the corresponding 5 epimers 4, 6, and 8 (EC₅₀ = 0.8, 2.3, and 2.0 μmol L⁻¹, respectively). A similar structure–activity relationship was observed for promotion of IL-8 production. This is the first report of modulation of IL-8 production by these sesquiterpene quinones.     

Interethnic differences of <Emphasis Type="Italic">PEPT2</Emphasis> (<Emphasis Type="Italic">SLC15A2</Emphasis>) polymorphism distribution and associations with cephalexin pharmacokinetics in healthy Asian subjects

Objectives  The aims of this study were to characterize the population frequency of PEPT2 (SLC15A2) polymorphic variants in three Asian ethnic populations, namely Chinese, Malay and Asian Indian, and to investigate the associations of ethnicity (Chinese vs. Asian Indian), PEPT2 haplotype and cephalexin pharmacokinetics in healthy Asian subjects. Methods   PEPT2 polymorphisms were screened from a cohort of 96 Chinese, 96 Malay and 96 Asian Indian subjects. Cephalexin (1000 mg, orally) pharmacokinetics was characterized in an additional 15 Chinese and 15 Asian Indian healthy subjects. These 30 subjects were subsequently genotyped for their PEPT2 polymorphisms. Results  In total, ten common single nucleotide polymorphisms (SNPs) were detected in the three populations, forming two PEPT2 haplotypes. There were significant ethnic differences in PEPT2 haplotype distribution: the frequencies of the *1 and *2 alleles were 0.307 and 0.693 in the Chinese population, 0.495 and 0.505 in the Malay population and 0.729 and 0.271 in Asian Indian population, respectively. The C _max of cephalexin was significantly lower in the Chinese (29.80 ± 4.09 μg ml⁻¹) population than in the Asian Indian one (33.29 ± 4.97 μg ml⁻¹; P = 0.045). This difference could be explained by the higher average body weight of the Chinese population. There was no other significant difference in cephalexin pharmacokinetics between either ethnic or PEPT2 genotype groups. Conclusion   PEPT2 polymorphism distributions differ significantly between Chinese, Malay and Asian Indian populations. However, cephalexin pharmacokinetics is not meaningfully different between Chinese and Asian Indians. The association between the PEPT2 haplotype and cephalexin pharmacokinetics could not be confirmed, and future studies under better controlled conditions are needed.     

Decreased prepulse inhibition and increased sensitivity to muscarinic,but not dopaminergic drugs in M<Subscript>5</Subscript> muscarinic acetylcholine receptor knockout mice

Rationale Schizophrenic patients show decreased measures of sensorimotor gating, such as prepulse inhibition of startle (PPI). In preclinical models, these measures may be used to predict antipsychotic activity. While current antipsychotic drugs act largely at dopamine receptors, the muscarinic acetylcholine receptors offer promising novel pharmacotherapy targets. Of these, the M₅ receptor gene was recently implicated in susceptibility to schizophrenia. Due to the lack of selective ligands, muscarinic receptor knockout mice have been generated to elucidate the roles of the five receptor subtypes (M₁–M₅). Objectives Here, we used M₅ receptor knockout (M₅−/−) mice to investigate the involvement of M₅ receptors in behavioral measures pertinent to schizophrenia. We tested the hypothesis that disruption of M₅ receptors affected PPI or the effects of muscarinic or dopaminergic agents in PPI or psychomotor stimulation. Materials and methods We measured PPI in M₅−/−, heterozygous and wild-type mice without drugs, and with clozapine (0.56–3.2 mg/kg) or haloperidol (0.32–3.2 mg/kg) alone, and as pretreatment to d-amphetamine. In addition, we evaluated locomotor stimulation by the muscarinic antagonist trihexyphenidyl (0.56–56 mg/kg) and by cocaine (3.2–56 mg/kg). Results The M₅−/− mice showed decreased PPI relative to wild-type mice, and clozapine appeared to reduce this difference, while haloperidol increased PPI regardless of genotype. The M₅−/− mice also showed more locomotor stimulation by trihexyphenidyl than wild-type mice, while cocaine had similar effects between genotypes. Conclusions These data suggest that disruption of the M₅ receptor gene affected sensorimotor gating mechanisms, increased sensitivity to clozapine and to the psychostimulant effects of muscarinic antagonists without modifying the effect of dopaminergic drugs.     

Inhibitory effect of Lysichiton camtschatcense extracts on Fe2+/ascorbate-induced lipid peroxidation in rat kidney and brain homogenates

Lysichiton camtschatcense is a well-known plant in Japan where it has been used as a traditional medicine by the “Ainu” people for the treatment of acute nephritis. It is presumed that L. camtschatcense has an inhibitory effect against nephritis caused by reactive oxygen species (ROS) owing to its antioxidant activities. Consequently, the antioxidant effect of L. camtschatcense extracts was assessed against Fe²⁺/ascorbic acid (AsA)-induced lipid peroxidation in rat kidney and brain homogenates. The antioxidant effect of the chloroform extract (CE) was more potent than that of the methanol extract (ME) for both homogenates. The antioxidant effect of both extracts was similar to those of α-tocopherol, a lipid-soluble antioxidant, and glutathione (GSH), a water-soluble antioxidant, which were used as reference compounds. Although CE showed a low radical-scavenging effect for superoxide anion radicals (O₂^·−) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, assessed by using an electron spin resonance (ESR) method, hydroxyl radicals (·OH) were markedly scavenged by more than 80%. On the other hand, ME showed more significant scavenging effect for DPPH radicals and O₂^·− than CE. These results suggest that the inhibitory effects of the L. camtschatcense extract on lipid peroxidation in rat kidney and brain are based on its high radical-scavenging effect against ·OH, O₂^·−, and lipid-derived radicals generated from the cell membrane.     

Antimicrobial activity of isolate HL-12 against Clavibacter michiganensis subsp. michiganensis in the presence of cadmium

An actinomycete, strain HL-12, that was isolated from a farmland on the Huajiachi campus of Zhejiang University was capable of inhibiting the growth of Clavibacter michiganensis subsp. michiganensis (Cmm) and was identified as a member of Streptomyces. Its antimicrobial activity against Cmm was measured using the agar plate sensitivity method in pure culture and evaluated by the inhibition ratio of Cmm in soil. The inhibitory activity of strain HL-12 against Cmm following exposure to low concentrations of Cd was greater than the inhibitory activity following exposure to high concentrations of Cd both in liquid culture and in soil. A stronger inhibition was also seen following a 24 h preculture in the presence of Cd in liquid culture. The growth of Cmm in soil was stimulated at low concentrations of Cd (<5.0 mg Cd kg⁻¹ dry soil) but inhibited when cultured in high concentrations of Cd (5.0 and 10.0 mg Cd kg⁻¹ dry soil). A higher inhibition ratio of strain HL-12 against Cmm, which was over 40% after soil incubation for 2 weeks, was observed following exposure to low concentrations of Cd (<5.0 mg Cd kg⁻¹ dry soil).     

Uptake and accumulation and oxidative stress in garlic (Allium sativum L.) under lead phytotoxicity

The effects of different concentrations of Pb on growth of Allium sativum L, Pb uptake and accumulation, antioxidant enzyme activity and malondialdehyde content were investigated. The results indicated that shoot growth at high concentration of Pb (10⁻³ M) and roots growth at 10⁻³ M and 10⁻⁴ M Pb were significantly inhibited. Lead ions were accumulated mainly in the roots and only small amounts were translocated to bulbs and shoots. SOD activities in shoot and roots exposed to 10⁻³ M Pb were observed to be high. Plants exposed to 10⁻³ M Pb showed a significant increase in POD activity in roots versus the control and other Pb treatments. In roots, CAT activity and MDA concentration at 10⁻³ M Pb is high significantly. The mechanisms of Pb toxicity and tolerance in garlic are briefly discussed.