Effects of long-term ouabain treatment on blood pressure, sodium excretion, and renal dopamine D1 receptor levels in rats

To examine the effects of chronic ouabain treatment on blood pressure (BP), sodium excretion, and renal dopamine D₁ receptor level, male Sprague-Dawley (SD) rats were treated with ouabain (27.8 μg kg⁻¹ d⁻¹) intraperitoneally for 5 weeks, and systolic blood pressure (SBP) were recorded weekly. After 5 weeks, sodium excretion and dopamine D₁ receptor agonist fenoldopam-mediated natriuresis were measured, and the expression and phosphorylation levels of the renal cortical dopamine D₁ receptor were confirmed by Western blot analysis. The effects of ouabain on fenoldopam-mediated inhibition of Na⁺-K⁺-ATPase activity were determined by colorimetric assays in human proximal tubular epithelial cells (HK-2 cells). After 5 weeks, the SBP in ouabain group was significantly higher than that in the control group (P < 0.01), but the sodium excretion and renal cortical D₁ receptor expression levels were reduced, and D₁ receptor phosphorylation levels were increased after ouabain treatment. Intravenous administration of fenoldopam caused an increased sodium excretion in control rats, but failed to induce natriuresis in ouabain-treated rats. In addition, fenoldopam induced a dose–respone (10⁻⁹ to 10⁻⁶ M) inhibition of Na⁺-K⁺-ATPase activity in HK-2 cells,but these effects were significantly diminished in HK-2 cells pretreated with nanomolar concentration of ouabain for 5 days (P < 0.01). We propose that the ouabain-induced reduction of the renal dopamine D₁ receptor function serves as a mechanism responsible for sodium retention, and this contributes to the hypertension induced by chronic ouabain treatment.     

Responses of Corpuscles of Stannius to intra-peritoneal vitamin-D3 administration in teleost Labeo rohita (Hamilton, 1822) reared in water with two different levels of calcium concentration

This study assessed the responses of vitamin-D₃ intraperitoneally injected to Rohu, Labeo rohita @ of 0 IU/kg bw (only solvent), 100 IU/kg bw and 500 IU/kg bw reared in 20 and 40 ppm of calcium (Ca) enriched water. The cellular changes in Corpuscles of Stannius (CS) gland, serum Ca, and inorganic phosphate (P_i) level were analysed up to the 60th day. Rohu administered with 100 IU/kg bw D₃ and exposed to 40 ppm Ca-rich water exhibited notable hyperplasia of CS compared with their control groups. Notable changes with high serum Ca level (13.87 ± 0.3 mg/dl) was detected on the 5th day in fish exposed to 40 ppm Ca-rich water, while related values attained (13.74 ± 0.1 mg/dl) only after 7 days in 20 ppm Ca-rich water of 500 IU/kg bw vitamin D₃ injection. Similarly, high serum P_i level (7.66 ± 0.2 mg/dl) in 40 ppm Ca injected with D₃ at 500 IU/kg bw. The results demonstrated that the Ca homeostasis of Labeo rohita is influenced by intra-peritoneal vitamin D₃. Progressive studies should be conducted by increasing the dose of vitamin D₃ to investigate optimum dose/supplement in feed for commercially important aquaculture teleost Labeo rohita for maximum and sustainable absorption of Ca from the variable water Calcium levels to maintain Ca²⁺ homeostasis.     

Prostacyclin (PGI2) effets on anterior pituitary hormones in the rat in vivo

Intravenous injection of 600 μg PGE₂ or PGI₂ significantly increased serum LH and prolactin levels in estradiol treated ovariectomized rats. There was no effect on serum FSH concentration. PGE₂ and PGI₂ stimulated LH release in a non-dose dependent manner, while prolactin levels were positively correlated with the dose administered following PGI₂ treatment. 6-keto-PGF_1α at a comparable dose had no effect on pituitary hormone levels. Subcutaneous administration of 1 mg/kg or 60 mg/kg PGI₂ for seven days significantly depressed serum LH level both in male and female rats. These doses had no effect on serum FSH or prolactin levels.     

Effects of acute and chronic trazodone administration on serum prolactin levels in adult female rats

Trazodone was tested for its ability to elevate serum prolactin levels in mature female rats. When the drug was administered acutely to female rats at doses up to 80 mg/kg ip, it induced a clear rise in serum prolactin levels, with a minimum effective dose of 20 mg/kg; blood trazodone levels at these doses were between 1.6–2.4 μg/ml. However, trazodone could not be considered to be a potent stimulator of prolactin secretion, since the injection of haloperidol at 2 mg/kg elevated serum prolactin to values twice those seen in animals receiving the 80 mg/kg dose of trazodone. When trazodone was administered chronically in the diet for two or four weeks, at an average daily dose of 80 mg/kg, serum trazodone levels were found to be 100–200 ng/ml when measured at each stage of the estrous cycle. Serum prolactin levels in trazodone-treated animals, however, did $\text{not}$ differ from those in control rats. Moreover, drug-treated animals showed normal proestrus surges in serum prolactin. The results of these studies thus indicate that acutely, at very high doses, trazodone probably can stimulate prolactin secretion modestly in female rats. However, when consumed chronically at 80 mg/kg/day, the drug has no effects on serum prolactin levels. Therefore, if trazodone stimulates prolactin secretion by altering neurotransmission across dopamine and/or serotonin synapses in brain, it is probably not potent in these actions, at least as concerns those dopamine and serotonin neurons that influence the secretion of prolactin.     

Further evidence for the involvement of D2, but not D1 dopamine receptors in dopaminergic control of striatal cholinergic transmission

The relative involvement of D₁ (cyclase linked) and D₂ dopamine receptors in dopaminergic control of striatal cholinergic transmission has been investigated in the rat by comparing the effects of SKF 38393 and LY 141865 (which act as specific agonists at D₁ and D₂ dopamine receptors, respectively) on striatal acetylcholine and dopamine metabolite concentrations and on the potassium-evoked release of ³H-acetylcholine from rat striatal slices. LY 141865 given systemically produced a dose-dependent increase in acetylcholine concentrations and a concomitant reduction of homovanillic and dihydroxyphenylacetic acid levels in the striatum (ED₅₀ 0.1 mg/kg) whereas SKF 38393 (1–30 mg/kg) did not. SKF 38393 (30 mg/kg) also failed to modify the LY 141865 (1 mg/kg) induced alterations of striatal acetylcholine and dopamine metabolite levels when given concomitantly with the latter compound. In experiments $\text{in vitro}$, LY 141865 reduced (EC₅₀ 0.14 μM), whereas SKF 38393 (up to 100 μM) failed to affect, the potassium-evoked release of ³H-acetylcholine from striatal slices. When given concomitantly with LY 141865, SKF 38393 (10 μM) did not modify the ability of the former compound to diminish striatal ³H-acetylcholine release. Finally, SKF 38393 also failed to affect the release of striatal ³H-acetylcholine after chemical lesion of the nigro-striatal dopaminergic pathway. The present results provide evidence for the involvement of D₂ but not D₁ dopamine receptors in dopaminergic control of striatal cholinergic transmission and indicate that D₁ dopamine receptors do not exert any modulatory influence on D₂ dopamine receptor mediated dopaminergic transmission.     

Effects of Fermenten supplementation to beef cattle

Two experiments were conducted to evaluate a commercially available supplemental N source for beef cattle (Fermenten^®; Church & Dwight Co., Inc., Princeton, NJ, USA). The first experiment evaluated kinetics of in vitro NH₃-N release using batch cultures of rumen fluid incubated with: control (no N added), soybean meal, urea, and Fermenten^®. Ammonia-N was measured at 0, 0.5, 2, 4, 6, 8, 12 and 24 h after incubation began. A treatment by time interaction (P<0.01) occurred in which, during the initial 2 h, Fermenten^® cultures had the highest (P<0.01) NH₃-N but, from 4 to 24 h, the highest (P<0.01) NH₃-N concentrations were with urea-incubated cultures. The total increase in NH₃-N concentrations from 0 to 24 h of incubation was less for Fermenten^® (P<0.01) than for the soybean meal and urea. The second experiment assessed effects of Fermenten^® supplementation on growth, blood parameters, voluntary forage intake and reproductive performance of beef heifers. Sixty heifers, stratified by initial body weight (BW), were randomly allocated to one of two treatments that consisted of iso-nitrogenous grain-based supplements containing either Fermenten^® (72 g/kg, as-fed) or urea (9.7 g/kg, as-fed). Supplements were offered three times weekly at a rate of 2.4 kg of dry matter per heifer daily. Shrunk BW was measured on days 0 and 112 for calculation of daily body weight gain. Body volume measurements were completed on days 0, 28, 56, 84 and 112, whereas pelvic area was assessed on days 0, 56 and 112. Blood samples were collected on days 28, 56, 84 and 112 for analysis of metabolites and hormones. On day 56, 2 heifers, which were randomly selected from each pasture, were placed in individual feeding stations for 26 days to determine treatment effects on voluntary forage intake. On day 112, all heifers were grouped by treatment and exposed to bulls for 60 days. Fewer heifers offered the Fermenten^® supplement attained puberty (P<0.05) and became pregnant during the study compared to heifers fed urea (0.60 and 0.93, respectively; P<0.01). Addition of Fermenten^® to batch cultures of rumen fluid rapidly increased NH₃-N concentrations, whereas further increases occurred in a slower and steady rate. Beef heifers fed a supplement containing Fermenten^® had similar growth and development, but inferior reproductive performance, than heifers fed a supplement containing urea.     

In vitro biohydrogenation of four dietary fats

This study was designed to determine in vitro rates of biohydrogenation of dietary unsaturated fatty acids by a mixed population of rumen microbes. The four dietary fats [Alifet High-Energy^® (AHE), Alifet-Repro^® (AR), Megalac^® (MG), and Energy Booster^® (EB)] differ in method of preparation, fatty acid composition, or both of these factors. Dietary fats (20 mg) were incubated with 4 mL strained rumen fluid diluted with 16 mL of medium, 0.8 mL of reducing solution buffer, and 200 mg of a synthetic diet (370 g cellulose, 370 g starch, and 160 g casein per kg DM) at 37 °C. Total contents were collected after 0, 6, 12, 24, or 36 h and change in fatty acid content determined. Disappearance of oleic acid was minimal (0.05–0.20) in AR and MG but moderate (about 0.60) in AHE and EB after 36 h of incubation. Rate of biohydrogenation of linoleic and linolenic acids from AR were similar (0.025 ± 0.009 h⁻¹) and 0.65 of these fatty acids remained intact after 36 h. Rate of biohydrogenation of linoleic acid was four times greater than for oleic acid (0.040 ± 0.013 h⁻¹ versus 0.009 ± 0.002 h⁻¹) in MG. Thus, 0.65 of the linoleic acid but only 0.20 of the oleic acid had disappeared from MG after 36 h. Trans-11 and trans-12 were the predominant trans-isomers in AHE and AR cultures whereas trans-9 and trans-10 were the predominant trans-isomers in EB and MG cultures. None of the dietary fats contained conjugated linoleic acid (CLA) but CLA was present in the incubation inoculum. The amount of CLA decreased with time but this was not affected by source of dietary fat. Most (0.90–0.95) of the long-chain fatty acids eicosapentaenoic (EPA) and docosahexaenoic (DHA) in AR remained after 36 h of incubation. Results demonstrate that biohydrogenation varied among fatty acids and among source of dietary fat and indicate that AR can be used to increase post-ruminal supply of linolenic, EPA and DHA.     

Synergistic hepatoprotective effect of Schisandrae lignans with Astragalus polysaccharides on chronic liver injury in rats

The aim of this study was to investigate the synergistic hepatoprotective effect of lignans from Fructus Schisandrae chinensis (LFS) with Astragalus polysaccharides (APS) on chronic liver injury in male Sprague-Dawley rats. Subcutaneous injection of 10% CCl₄ twice a week for 3 months resulted in significantly (p<0.001) elevated serum alanine aminotransferase (ALT), asparate aminotransferase (AST), alkaline phosphatase (ALP) activities compared to controls. In the liver, significantly elevated levels (p<0.001) of malondialdehyde (MDA), lowered levels of reduced glutathione (GSH) (p<0.05) and catalase (CAT) (p<0.001), superoxide dismutase (SOD) (p<0.01)were observed following CCl₄ administration. ‘LFS+ASP’ treatment of rats at doses of ‘LFS (45 mg/kg)+APS (150 mg/kg)’ and ‘LFS (135 mg/kg)+APS (450 mg/kg)’ displayed hepatoprotective and antioxidative effects than the administration of either LFS or APS, as evident by lower (p<0.005 or 0.001) levels of serum ALT, AST, ALP and hepatic MDA (p<0.001) concentration, as well as higher SOD (p<0.05 or 0.005), CAT activities(p<0.01 or 0.005), GSH concentration (p<0.05 or 0.005) compared to the toxin treated group. Histopathological examinations revealed severe fatty degeneration in the toxin group, and mild damage in groups treated with ‘LFS+APS’ were observed. The coefficients drug interaction (CDI) between each individual drug and their combination (at the same dose of their single treatment) of these foregoing parameters were all less than 1, indicating that LFS and APS display hepatoprotective and antioxidant properties and act in a synergistic manner in CCl₄ induced liver injury in rats.     

Clozapine,a dopamine DA4 receptor antagonist,reduces gastric acid secretion and stress-induced gastric mucosal injury

Dopamine and its agonists modulate a variety of gastrointestinal functions. In light of the increasing attention directed toward novel dopamine receptors and compounds that are active at these sites, we examined the effects of a dopamine D₄ antagonist and putative antipsychotic, clozapine, in a model of conscious basal gastric acid secretion and in a model of stress-induced gastric mucosal injury. At a dose of 10.0 mg/kg i.p., clozapine significantly inhibited basal gastric acid secretion by 84% relative to vehicle. Lower doses (2.5 and 5.0 mg/kg) were inactive. Doses of 2.5, 5.0 and 7.5 mg/kg i.p. all significantly reduced restraint stress-induced gastric mucosal injury in rats. The highest dose inhibited gastric lesions by 70% relative to vehicle. We conclude that dopamine D₄ receptors, present in high concentrations in mesolimbic brain regions, modulate gastric function and pathology in addition to mesolimbic D₁ receptors, whose role in gastrointestinal function is already established.     

Antidiabetic and antilipidemic effect of eremanthin from Costus speciosus (Koen.)Sm., in STZ-induced diabetic rats

The increasing prevalence of diabetes mellitus worldwide is an issue of major socio-economic concern. Diabetes mellitus is a complex and a multifarious group of disorders that disturbs the metabolism of carbohydrates, fat and protein. Medicinal plants play an important role in the management of diabetes mellitus especially in developing countries. Costus speciosus is widely used in Indian medicine to treat various diseases. Eremanthin was isolated from C. speciosus. The structure was identified using gas chromatography–mass spectrometry (GC–MS) analysis. Eremanthin was administered to streptozotocin (STZ) (50 mg/kg bw) induced diabetic male Wistar rats at different doses (5, 10, 20 mg/kg bw) for 60 days. Plasma glucose level was significantly (p < 0.05) reduced in a dose dependent manner when compared to the control. In addition, oral administration of eremanthin (20 mg/kg bw) significantly decreased glycosylated hemoglobin (HbA_1c), serum total cholesterol, triglyceride, LDL-cholesterol and at the same time markedly increased plasma insulin, tissue glycogen, HDL-cholesterol and serum protein. Eremanthin also restored the altered plasma enzyme (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, alkaline phosphatase and acid phosphatase) levels to near normal. Results of this experimental study indicated that eremanthin possessed hypoglycemic and hypolipidemic activities and hence it could be used as a drug for treating diabetes.     

Cariprazine (RGH-188), a potent D3/D2 dopamine receptor partial agonist, binds to dopamine D3 receptors in vivo and shows antipsychotic-like and procognitive effects in rodents

We investigated the in vivo effects of orally administered cariprazine (RGH-188; trans-N-{4-[2-[4-(2,3-dichlorophenyl)-piperazin-1-yl]-ethyl]-cyclohexyl}-N′,N′-dimethyl-urea), a D₃/D₂ dopamine receptor partial agonist with ∼10-fold preference for the D₃ receptor. Oral bioavailability of cariprazine at a dose of 1 mg/kg in rats was 52% with peak plasma concentrations of 91 ng/mL. Cariprazine 10 mg/kg had good blood-brain barrier penetration, with a brain/plasma AUC ratio of 7.6:1. In rats, cariprazine showed dose-dependent in vivo displacement of [³H](+)-PHNO, a dopamine D₃ receptor-preferring radiotracer, in the D₃ receptor-rich region of cerebellar lobules 9 and 10. Its potent inhibition of apomorphine-induced climbing in mice (ED₅₀ = 0.27 mg/kg) was sustained for 8 h. Cariprazine blocked amphetamine-induced hyperactivity (ED₅₀ = 0.12 mg/kg) and conditioned avoidance response (CAR) (ED₅₀ = 0.84 mg/kg) in rats, and inhibited the locomotor-stimulating effects of the noncompetitive NMDA antagonists MK-801 (ED₅₀ = 0.049 mg/kg) and phencyclidine (ED₅₀ = 0.09 mg/kg) in mice and rats, respectively. It reduced novelty-induced motor activity of mice (ED₅₀ = 0.11 mg/kg) and rats (ED₅₀ = 0.18 mg/kg) with a maximal effect of 70% in both species. Cariprazine produced no catalepsy in rats at up to 100-fold dose of its CAR inhibitory ED₅₀ value. Cariprazine 0.02-0.08 mg/kg significantly improved the learning performance of scopolamine-treated rats in a water-labyrinth learning paradigm. Though risperidone, olanzapine, and aripiprazole showed antipsychotic-like activity in many of these assays, they were less active against phencyclidine and more cataleptogenic than cariprazine, and had no significant effect in the learning task. The distinct in vivo profile of cariprazine may be due to its higher affinity and in vivo binding to D₃ receptors versus currently marketed typical and atypical antipsychotics.     

Clozapine increases rat serum prolactin levels.

Clozapine differs from other anti-psychotic drugs in that is produces little or no extrapyramidal side effects. The effects of clozapine on rat brain dopamine differ markedly from those of the neuroleptic drugs. The neuroleptics increase rat serum prolactin levels which has been attributed to their dopamine receptor blocking properties. We found that clozapine markedly increased serum prolactin levels in male rats when injected intraperitoneally in doses of 5, 10, 50 and 100 mg/kg. Serum prolactin levels after 5 mg/kg clozapine were significantly less than in rats given 10, 50 and 100 mg/kg which did not significantly differ from each other. Serum prolactin after 10 mg/kg clozapine was significantly greater than after chlorpromazine, 5 mg/kg and haloperidol, 0.5 mg/kg. The increases in serum prolactin are attributed to clozapine's ability to produce dopamine blockade or to inhibit nerve impulse-dopamine release, or both. The capacity of clozapine to affect brain serotonin and norepinephrine metabolism and its strong anti-cholinergic properties are probably not involved in its ability to increase serum prolactin.     

Effects of Zinc Glycine Chelate on Oxidative Stress,Contents of Trace Elements,and Intestinal Morphology in Broilers

Three hundred and sixty healthy Ross × Ross 1-day-old broilers were used to study the effects of zinc glycine chelate (Zn-Gly) on oxidative stress, contents of trace elements, and intestinal morphology. All broilers were randomly assigned to six treatment groups, which replicates three times. Diets were as follows: (1) control (containing 29.3 mg zinc (Zn)/kg basic diet (0–21 days) and 27.8 mg Zn/kg (22–42 days)); (2) basic diet plus 30 mg Zn/kg from Zn-Gly; (3) basic diet plus 60 mg Zn/kg from Zn-Gly; (4) basic diet plus 90 mg Zn/kg from Zn-Gly; (5) basic diet plus 120 mg Zn/kg from Zn-Gly; and (6) positive control, basic diet plus 120 mg Zn/kg from zinc sulfate (ZnSO₄). The results showed that the addition of 90 or 120 mg/kg Zn-Gly led to an improvement of activity of Cu/Zn superoxide dismutase and glutathione peroxidase and a reduction of malondialdehyde content in livers at 21 and 42 days. With 90 mg/kg Zn-Gly, the content of sera zinc increased by 17.55% (P < 0.05) in 21-day broilers and 10.77% (P > 0.05) in 42-day broilers compared with that of the control. Adding 120 mg/kg Zn-Gly or ZnSO₄ to broilers' diets greatly enhanced the content of zinc in feces at 21 days (P < 0.05) and at 42 days (P < 0.05). For 42-day chickens, increased villus height and decreased crypt depth of the jejunum could be observed in the second growth stage of broilers fed with 90 mg/kg Zn-Gly. Also, intestinal wall thickness decreased (P < 0.05). In addition, adding 90 mg/kg Zn-Gly to the diet markedly elevated villus length of duodenum and decreased crypt depth of ileum (P < 0.05) in 42-day broilers.     

High-performance liquid chromatographic determination of paclitaxel in rat serum: application to a toxicokinetic study

A simple and sensitive high-performance liquid chromatographic method is described for the determination of paclitaxel (Taxol^®) at 230 nm using a Nucleosil C₁₈ (5 μm) column and a methanol–water (70:30, v/v) mobile phase following a single-step extraction from serum with dichloromethane. The assay was validated against the classical criteria and was applied to a toxicokinetic study in rats after one or five, one per week) intraperitoneal administrations of 16 mg/kg Taxol^®.     

Silybum marianum: non‐medical exploitation of the species

Silybum marianum (milk thistle) is currently utilised as a medicinal plant which provides raw material for the production of silymarin. Silymarin is composed of a group of flavonolignans that are well known and studied for their medicinal properties. However, the biomass yield potential and the chemical composition of its biomass suggest opportunities for much broader utilisation of S. marianum. This paper reviews the available literature about S. marianum biomass productivity and composition and about properties of products and byproducts of silymarin extraction. Alternative uses of whole plant biomass include fodder, bioenergy production and phytoremediation. Byproducts of silymarin extraction such as oil and flour have possible applications in food, feed and cosmetics. Moreover, the review explores potential alternative applications of silymarin. We conclude that a pivotal issue for further utilisation of S. marianum is the development of improved cultivars suited for the different possible utilisations.     

Comparative Tolerances of Various <Emphasis Type="Italic">Beauveria bassiana</Emphasis> Isolates to UV-B Irradiation with a Description of a Modeling Method to Assess Lethal Dose

The tolerances of 20 Beauveria bassiana isolates derived from host insects worldwide to UV-B irradiation were assessed quantitatively in multi-dose bioassays. Conidial suspensions of the isolates smeared on glass slides were exposed to the gradient UV-B doses of 0.1–1.6 J cm⁻² (D), which generated from 0.75 to 10.17 min irradiation of weighted 312-nm wavelength at 2.0–2.61 mW cm⁻². Irradiated conidia were then incubated for 24 h at 25°C under saturated humidity. The ratio of germination at each dose over that in the blank control was defined as survival index (I _s). For all isolates, the I _s − D observations fit well with the survival model I _s = 1/[1 + exp(a + bD)] (0.94 ≤ r ² ≤ 0.99) generated widely spanned lethal doses of 0.154–0.928, 0.240–1.139, and 0.383–1.493 J cm⁻² for their losses of 50%, 75%, and 95% viabilities, respectively. These were far below the solar UV-B dose of 2.439 J cm⁻² measured in a sunny day during the summer. The large variation of UV-B tolerance among the isolates indicates a necessity to select UV-tolerant candidates for formulations applied to insect control during summer. The highly efficient bioassay method was developed to measure accurately the UV-B tolerances of fungal biocontrol agents as lethal doses.     

Effects of stocking density during live transportation on haematological parameters of Siberian sturgeon (Acipenser baerii,Brandt, 1869)

In this study, we investigated the effects of different stocking densities water quality and blood parameters during the transportation of the Siberian sturgeon (Acipenser baerii). Experiments were carried out in high-density polyethylene tank with three different stocking densities (50, 100 and 150 kg/m³) for 20 h. Ammonium nitrogen (NH₄-N) and nitrite nitrogen (NO₂-N) were measured in the water samples. The erythrocyte, leucocyte, haematocrit (HCT), haemoglobin (Hb), cortisol, and sodium ion (Na⁺) were measured in blood samples. Ammonium nitrogen and nitrite nitrogen concentrations in the water have increased in parallel with the stocking density depending on the time. In the highest stocking density, the maximum levels of NH₄-N and NO₂-N at the 16^th h reached 2.64 mg/L and 4.74 mg/L, respectively. Erythrocyte, leucocyte, HCT, and Hb values did not differ significantly between the experimental groups (p > .05). The results showed that fish could be transported safely for 20 h in 15℃ water temperature at 50 kg/m³ stocking density; however, stocking density of 100 kg/m³ and over could threaten fish welfare and health as from 16^th h.     

Efficacy of three commercially available ballast water biocides against vegetative microalgae, dinoflagellate cysts and bacteria

One proposed solution to the problem of ballast-mediated aquatic invasions involves chemically treating ballast water to kill key target organisms. Here, we examine the efficacy of three commercially available ballast water biocides using vegetative microalgae, dinoflagellate resting cysts and bacteria as test organisms. Chemicals tested were the ballast water biocides SeaKleen^® and Peraclean^® Ocean, and the chlorine dioxide biocide Vibrex^®. Results demonstrate that the applicability of each of the three chemical biocides as a routine ballast water treatment is limited by factors such as cost, biological effectiveness and possible residual toxicity of the discharged ballast water (assessed on the basis of impact on motility of vegetative marine microalgae). Of the three biocides tested, Peraclean^® Ocean appears to hold the most potential; however its effectiveness in shipboard trials is yet to be proven. Peraclean^® Ocean was biodegradable within 2–6 weeks (initial concentration of 200 ppm), could effectively inactivate resting cysts of the marine dinoflagellates Gymnodinium catenatum, Alexandrium catenella and Protoceratium reticulatum at 400 ppm, could control bacterial growth of Escherichia coli, Staphylococcus aureus, Listeria innocua and Vibrio alginolyticus at 125–250 ppm, and could eliminate vegetative dinoflagellate cells at a concentration of 100 ppm. SeaKleen^® eliminated vegetative microalgae at 2 ppm and could control resting cysts of the dinoflagellates G. catenatum and P. reticulatum at a concentration of 6 and 10 ppm, respectively, when exposed for a period of 2 weeks. SeaKleen^® did not inactivate resting cysts of A. catenella at a concentration of 10 ppm and was found to degrade at a rate that could result in the discharge of residual toxic water into the marine environment. Together with the poor bactericidal properties of SeaKleen^® (100–200 ppm required), this may limit the use of this biocide as a routine treatment option. Vibrex^® is not a suitable ballast water treatment option due to the need for hydrochloric acid as an activator, however it was found to be the most effective against bacteria (complete inhibition at 15 ppm) indicating that onboard chlorine dioxide generators may provide an effective bacterial treatment option. The performance of these biocides was adversely influenced by a variety of factors including low water temperatures (6 °C compared to 17 °C), light versus dark conditions, and the presence of humus-rich seawater and ballast water sediments.     

Chronic Antagonist Treatment Does not Alter the Mode of Interaction of Dopamine with Rat Striatal Dopamine Receptors

Abstract

Chronic treatment with the D₁ and D₂ dopamine receptor antagonists SCH 23390 (0.5 mg/kg) and haloperidol decanoate (25 mg/kg) caused an up-regulation in D₁ and D₂ receptor densities, respectively, with no change in K_D. Dopamine (20 μM) interacted with both receptor subtypes in a mixed competitive/non-competitive manner, causing a reduction in ligand binding affinity and an apparent decrease in receptor density. In the presence of dopamine, both vehicle-treated and SCH 23390-treated striatal preparations showed a significant loss in affinity for ³H-SCH 23390 binding to D₁ receptors and a decrease in D₁ receptor density of approximately 26%. Similarly, dopamine caused a substantial loss in ³H-spiperone binding affinity to D₂ receptors and a 46% decrease in B_max in both vehicle-treated and haloperidol-treated membranes. Thus, receptor up-regulation does not appear to alter the mode of interaction of dopamine with rat striatal dopamine receptors.