Synthesis and evaluation of new mixed "2 + 1" Re, 99mTc and 186Re tricarbonyl dithiocarbamate complexes with different monodentate ligands.

A series of "2 + 1" mixed ligand tricarbonyl complexes of the general formula fac-[Re/99mTc/186Re(CO)3(DDTC)(L)] containing diethyldithiocarbamate (DDTC) as a monoanionic bidentate ligand and a series of monodentate ligands L was synthesized, characterized and evaluated. The impact of ligand L on the radiochemical yield (RCY) and biodistribution of the final compounds was also investigated. DDTC and the appropriate L ligand [cyclohexyl isocyanide (cisc), tert-butyl isocyanide (tbi), triphenylphosphine (PPh3), methyldiphenylphosphine (PPh2Me), triphenylarsine (AsPh3), imidazole (im), and 4-aminopyridine (4AP)] readily reacted in equimolar amounts with the [Et4N]2[Re(CO)3Br3] precursor to afford fac-[Re(CO)3(DDTC)(cisc)], Re1, fac-[Re(CO)3(DDTC)(tbi)], Re2, fac-[Re(CO)3(DDTC)(PPh3)], Re3, fac-[Re(CO)3(DDTC)(PPh2Me)], Re4, fac-[Re(CO)3(DDTC)(AsPh3)], Re5, fac-[Re(CO)3(DDTC)(im)], Re6 and fac-[Re(CO)3(DDTC)(4AP)], Re7, complexes in high yields (>80%). All Re complexes were fully characterized by IR, NMR, and in addition Re4, Re5, and Re7 with X-ray crystallography. Analogous reactions as performed with Re were subsequently explored on the 99mTc and 186Re-tracer levels using the corresponding fac-[99mTc/186Re(CO)3(H2O)3]+ precursor. Complexes 99mTc1 - 99mTc5, 186Re1 and 186Re3 were obtained in high radiochemical yield (>91%), while the complexes 99mTc6, 99mTc7 and 186Re7 formed with radiochemical yields of 55%, 28%, and 75%, respectively. The 99mTc and 186Re-complexes were characterized by comparative HPLC analysis using the analogous Re complexes. During histidine and cysteine challenge experiments at 37 °C through 6 h, complexes 99mTc1 - 99mTc5 remained > 92% stable, while complexes 99mTc6 and 99mTc7 remained only 8% stable through 3 h. Similar studies for 186Re-complexes showed that 186Re1 and 186Re3 remained > 95% stable for up to 48 h, while 186Re7 had decreased to 7% after 3 h. LogD7.4 data of 99mTc1 - 99mTc5, 186Re1, and 186Re3 complexes, which ranged from 2.59 to 3.39, suggested high lipophilicity. Biodistribution studies in healthy Swiss albino mice showed hepatobiliary excretion for 99mTc1, 99mTc2, and 99mTc4, fast blood clearance for 99mTc4, while high liver uptake and retention for 99mTc3 and 99mTc5 were measured. Moreover, 99mTc2 showed high accumulation in the lungs with sustained retention (52.80% ID/g at 4 h p.i.) and significant brain uptake at 2 min p.i. (1.89% ID/g). The study showed the great influence of monodentate ligand in the synthesis and biodistribution of the mixed ligand complexes.

Discovery of a crystalline sulforaphane analog with good solid-state stability and engagement of the Nrf2 pathway in vitro and in vivo.

The antioxidant natural product sulforaphane (SFN) is an oil with poor aqueous and thermal stability. Recent work with SFN has sought to optimize methods of formulation for oral and topical administration. Herein we report the design of new analogs of SFN with the goal of improving stability and drug-like properties. Lead compounds were selected based on potency in a cellular screen and physicochemical properties. Among these, 12 had good aqueous solubility, permeability and long-term solid-state stability at 23 °C. Compound 12 also displayed comparable or better efficacy in cellular assays relative to SFN and had in vivo activity in a mouse cigarette smoke challenge model of acute oxidative stress.

Comparison of 99mTc-UBI 29-41, 99mTc-ciprofloxacin, 99mTc-ciprofloxacin dithiocarbamate and 111In-biotin for targeting experimental Staphylococcus aureus and Escherichia coli foreign-body infections: an ex-vivo study.

BACKGROUND: Diagnosis of implant-associated infection is challenging. Several radiopharmaceuticals have been described but direct comparisons are limited. Here we compared in vitro and in an animal model 99mTc-UBI, 99mTc-ciprofloxacin, 99mTcN-CiproCS2 and 111In-DTPA-biotin for targeting E. coli (ATCC 25922) and S. aureus (ATCC 43335). METHODS: Stability controls were performed with the labelled radiopharmaceuticals during 6 hours in saline and serum. The in vitro binding to viable or killed bacteria was evaluated at 37 °C and 4 °C. For in vivo studies, Teflon cages were subcutaneously implanted in mice, followed by percutaneous infection. Biodistribution of i.v. injected radiolabelled radiopharmaceuticals were evaluated during 24 h in cages and dissected tissues. RESULTS: Labelling efficiency of all radiopharmaceuticals ranged between 94% and 98%, with high stability both in saline and in human serum. In vitro binding assays displayed a rapid but poor bacterial binding for all tested agents. Similar binding kinetic occurred also with heat-killed and ethanol-killed bacteria. In the tissue cage model, infection was detected at different time points: 99mTc-UBI and 99mTcN-CiproCS2 showed higher infected cage/sterile cage ratio at 24 hours for both E. coli and S. aureus; 99mTc-Ciprofloxacin at 24 hours for both E. coli and at 4 hours for S. aureus; 111In-DTPA-biotin accumulates faster in both E. coli and S. aureus infected cages. CONCLUSIONS: 99mTc-UBI, 99mTcN-CiproCS2 showed poor in vitro binding but good in vivo binding to E. coli only. 111In-DTPA-biotin showed poor in vitro binding but good in vivo binding to S. aureus and poor to E. coli. 99mTc-Ciprofloxacin showed poor in vitro binding but good in vivo binding to all tested bacteria. The mechanism of accumulation in infected sites remains to be elucidated.

Human plasma concentrations of herbicidal carbamate molinate extrapolated from the pharmacokinetics established in in vivo experiments with chimeric mice with humanized liver and physiologically based pharmacokinetic modeling.

To predict concentrations in humans of the herbicidal carbamate molinate, used exclusively in rice cultivation, a forward dosimetry approach was carried out using data from lowest-observed-adverse-effect-level doses orally administered to rats, wild type mice, and chimeric mice with humanized liver and from in vitro human and rodent experiments. Human liver microsomes preferentially mediated hydroxylation of molinate, but rat livers additionally produced molinate sulfoxide and an unidentified metabolite. Adjusted animal biomonitoring equivalents for molinate and its primary sulfoxide from animal studies were scaled to human biomonitoring equivalents using known species allometric scaling factors and human metabolic data with a simple physiologically based pharmacokinetic (PBPK) model. The slower disposition of molinate and accumulation of molinate sulfoxide in humans were estimated by modeling after single and multiple doses compared with elimination in rodents. The results from simplified PBPK modeling in combination with chimeric mice with humanized liver suggest that ratios of estimated parameters of molinate sulfoxide exposure in humans to those in rats were three times as many as general safety factor of 10 for species difference in toxicokinetics. Thus, careful regulatory decision is needed when evaluating the human risk resulting from exposure to low doses of molinate and related carbamates based on data obtained from rats.

Preparation and biological evaluation of (99m) TcN-labeled pteroyl-lys derivative as a potential folate receptor imaging agent.

In order to develop a novel (99m) Tc-labeled folate receptor (FR) imaging agent, a dithiocarbamate derivative, pteroyl-lys-DTC, was synthesized and radiolabeled with (99m) Tc through the [(99m) TcN](2+) intermediate. The radiochemical purity of the corresponding (99m) Tc-complex, (99m) TcN-pteroyl-lys-DTC, was over 95% as measured by reversed-phase HPLC. The (99m) TcN complex was stable under physiological conditions. (99m) TcN-pteroyl-lys-DTC exhibited specific FR binding in FR-positive KB cells in vitro. The biodistribution in tumor-bearing mice showed that the (99m) TcN-labeled radiotracer had good uptake (3.56 ± 0.09%ID/g at 2 h postinjection) in FR-positive KB tumors, as well as in the kidneys (30.34 ± 3.53%ID/g at 2 h postinjection). After coinjection with excess folic acid, the uptake in tumor and kidneys was significantly blocked. The results indicated that (99m) TcN-pteroyl-lys-DTC was able to target the FR-positive tumor cells and tissues specifically both in vitro and in vivo.

Disulfiram metabolite S-methyl-N,N-diethylthiocarbamate quantitation in human plasma with reverse phase ultra performance liquid chromatography and mass spectrometry.

Disulfiram has been used extensively for alcohol abuse and may have a role in treatment for cocaine addiction. Recent data suggest that disulfiram may also reactivate latent HIV in reservoirs. Disulfiram has complex pharmacokinetics with rapid metabolism to active metabolites, including S-methyl-N,N-diethylthiocarbamate (DET-Me) which is formed from cytochrome P450 (CYP450). Assessing disulfiram in HIV-infected individuals with a CYP450 inducing drug (e.g., efavirenz) or a CYP450 inhibiting drug (e.g., HIV-1 protease inhibitors) requires an assay that can measure a metabolite that is formed directly via CYP450 oxidation. Therefore, an assay to measure concentrations of DET-Me in human plasma was validated. DET-Me and the internal standard, S-ethyldipropylthiocarbamate (EPTC) were separated by isocratic ultra performance liquid chromatography using a Waters Acquity HSS T3 column (2.1 mm × 100 mm, 1.8 µm) and detection via electrospray coupled to a triple quadrupole mass spectrometer. Multiple reaction monitoring in positive mode was used with DET-Me at 148/100 and the internal standard at 190/128 with a linear range of 0.500-50.0 ng/mL with a 5 min run time. Human plasma (500 µL) was extracted using a solid phase procedure. The interassay variation ranged from 1.86 to 7.74% while the intra assay variation ranged from 3.38 to 5.94% over three days. Representative results are provided from samples collected from subjects receiving daily doses of disulfiram 62.5mg or 250 mg.

[Comparison of the biodistribution of four contrast agents in nude mice bearing NCI-H358 human lung cancer and evaluation of their value in diagnostic imaging].

OBJECTIVE: To compare the uptake of four contrast agents: (99)Tc(m)-RGD-4CK, (99)Tc(m)-N(NOET)(2), (99)Tc(m)-MIBI and (18)F-FDG in Bal B/c nude mice bearing human non-small cell lung cancer NCI-H358 and evaluate their diagnostic value in low-metabolic lung cancer. METHODS: Human bronchioloalveolar carcinoma NCI-H358 cells were subcutaneously inoculated in Bal B/c nude mice to establish mouse models bearing human lung cancer. Twenty tumor-bearing nude mice were given injection of the four contrast agent, respectively, 5 mice in each group. SPECT imaging and biodistribution of the 4 tracers in the tumor-bearing nude mice were performed. The ratios of tumor to non-tumor (T/NT) of the tracers were compared. RESULTS: The results from semi-quantification of the planar image and assessment of biodistribution showed that tumor to contralateral muscle activity ratios (T/NT) of the four tracers had statistically significant difference between each two of the four tracer groups of tumor-bearing mice (P < 0.001), with a highest value of T/NT ratio in the (99)Tc(m)-RGD-4CK group. CONCLUSIONS: NCI-H358 tumors show a higher uptake of (99)Tc(m)-RGD-4CK than (18)F-FDG. It suggests that when diagnosing a well-differentiated lung cancer such as bronchioloalveolar carcinoma, the contrast agent (99)Tc(m)-RGD-4CK may be more sensitive than (18)F-FDG, and it may become a promising contrast agent in tumor imaging diagnosis.

Enhanced antitumor efficacy of folate-linked liposomal doxorubicin with TGF-ß type I receptor inhibitor.

Tumor cell targeting of drug carriers is a promising strategy and uses the attachment of various ligands to enhance the therapeutic potential of chemotherapy agents. Folic acid is a high-affinity ligand for folate receptor, which is a functional tumor-specific receptor. The transforming growth factor (TGF)-ß type I receptor (TßR-I) inhibitor A-83-01 was expected to enhance the accumulation of nanocarriers in tumors by changing the microvascular environment. To enhance the therapeutic effect of folate-linked liposomal doxorubicin (F-SL), we co-administrated F-SL with A-83-01. Intraperitoneally injected A-83-01-induced alterations in the cancer-associated neovasculature were examined by magnetic resonance imaging (MRI) and histological analysis. The targeting efficacy of single intravenous injections of F-SL combined with A-83-01 was evaluated by measurement of the biodistribution and the antitumor effect in mice bearing murine lung carcinoma M109. A-83-01 temporarily changed the tumor vasculature around 3 h post injection. A-83-01 induced 1.7-fold higher drug accumulation of F-SL in the tumor than liposome alone at 24 h post injection. Moreover F-SL co-administrated with A-83-01 showed significantly greater antitumor activity than F-SL alone. This study shows that co-administration of TßR-I inhibitor will open a new strategy for the use of FR-targeting nanocarriers for cancer treatment.

Pre-clinical safety evaluation of pyrrolidine dithiocarbamate.

Pyrrolidine dithiocarbamate (PDTC) was examined for its potential in the intranasal treatment of human rhinovirus infections. Prior to clinical testing, a comprehensive non-clinical programme was performed to evaluate the general toxicity of PDTC. The animal experiments included investigations in rodents with study durations ranging from single dose to repeated dosing over a period of 28 days. The routes of administration were intranasal, inhalative, oral and intravenous for single-dose toxicity and pharmacokinetic studies, and intranasal for repeated dose studies. Blood and tissue samples were obtained from PDTC-treated rats to analyse pharmacokinetics and tissue distribution. Accumulation of selected metals due to PDTC treatment was examined in liver, brain, nerves and fat tissues.

Biological in vitro and in vivo studies of a series of new asymmetrical cationic [99mTc(N)(DTC-Ln)(PNP)]+ complex (DTC-Ln = alicyclic dithiocarbamate and PNP = diphosphinoamine).

(99m)Tc(N)-DBODC5 is a cationic mixed compound under clinical investigation as potential myocardial imaging agent. In spite of this, analogously to the other cationic (99m)Tc-agents, presents a relatively low first-pass extraction. Thus, modification of (99m)Tc(N)-DBODC(5) direct to increase its first-pass extraction keeping unaltered the favorable imaging properties would be desirable. This work describes the synthesis and biological evaluation of a series of novel cationic (99m)Tc-nitrido complexes, of general formula [(99m)TcN(DTC-Ln)(PNP)](+) (DTC-Ln= alicyclic dithiocarbamates; PNP = diphosphinoamine), as potential radiotracers for myocardial perfusion imaging. The synthesis of cationic (99m)Tc-(N)-complexes were accomplished in two steps. Biodistribution studies were performed in rats and compared with the distribution profiles of (99m)Tc(N)-DBODC5 and (99m)Tc-Sestamibi. The metabolisms of the most promising compounds were evaluated by HPLC methods. Biological studies revealed that most of the complexes have a high initial and persistent heart uptake with rapid clearance from nontarget tissues. Among tested compounds, 2 and 12 showed improved heart uptake with respect to the gold standard (99m)Tc-complexes with favorable heart-to-liver and slightly lower heart-to-lung ratios. Chromatographic profiles of (99m)Tc(N)-radioactivity extracted from tissues and fluids were coincident with the native compound evidencing remarkable in vivo stability of these agents. This study shows that the incorporation of alicyclic dithiocarbamate in the [(99m)Tc(N)(PNP)](+) building block yields to a significant increase of the heart uptake at early injection point suggesting that the first-pass extraction fraction of these novel complexes may be increased with respect to the other cationic (99m)Tc-agents keeping almost unaltered the favorable target/nontarget ratios.

Development of PBPK model of molinate and molinate sulfoxide in rats and humans.

Molinate has been widely used as a pre-emergent herbicide in the rice fields of California's Central Valley. In rat studies, the metabolite molinate sulfoxide is suspected of causing testicular toxicity after exposure to molinate. The sulfoxide is generated in the liver and can circulate in the blood, eventually reaching the testis. Man qualitatively produces the same molinate metabolites as the rat. To extrapolate the reproductive risk to man, the present study outlines the development of a preliminary PBPK (physiologically-based pharmacokinetic) model, validation in the rat and extrapolation to man. The preliminary seven-compartment PBPK model for molinate was constructed for the adult, male Sprague-Dawley rat that employed both flow-limited (blood, kidney, liver, rapid-perfused tissues and slowly perfused tissues) and diffusion-limited (fat) rate equations. The systemic circulation connects the various compartments. The simulations predict the molinate blood concentrations of the rat blood and testes compartment favorably with the profiles obtained from 10 and 100mg/kg po or 1.5 and 15mg/kg iv doses. Human physiological parameters were substituted into the oral dosed model and the simulations closely predicted the molinate blood concentration obtained from 5.06mg oral dose. A sensitivity analysis determined for an oral dose that peak blood molinate concentrations were most responsive to the blood flows to kidney and fat compartments while testicular molinate sulfoxide concentrations depended on molinate sulfoxide partition coefficients for the testes compartment and the K(m) for glutathione conjugation of molinate sulfoxide in the liver compartment.

Synthesis and biodistribution of a novel (99m)TcN complex of ciprofloxacin dithiocarbamate as a potential agent for infection imaging.

The ciprofloxacin dithiocarbamate (CPFXDTC) was synthesized and radiolabeled with [(99m)TcN](2+) intermediate to form the (99m)TcN-CPFXDTC complex in high yield (>95%). No decomposition of the complex at room temperature was observed over a period of 6 h. Its partition coefficient indicated that it was a good lipophilic complex. The bacterial binding assay studies showed (99m)TcN-CPFXDTC had a better binding affinity as compared with (99m)Tc-ciprofloxacin. Biodistribution results in induced infection mice showed (99m)TcN-CPFXDTC had higher uptake at the sites of infection and better abscess/blood ratio than that of (99m)Tc-ciprofloxacin, suggesting (99m)TcN-CPFXDTC would be a novel potential infection imaging agent.

Thiodicarb and methomyl tissue distribution in a fatal multiple compounds poisoning.

Thiodicarb is a nonsystemic carbamate insecticide whose acetylcholinesterase activity is related to its main methomyl degradation product. A 40-year-old woman was found dead in her car. Empty packages of medicines and an open bottle of Larvin containing thiodicarb were found near her body. No signs of violence nor traumatic injuries were noticed upon autopsy, and police investigations strongly suggested a suicide. Systematic toxicological analysis performed on postmortem specimens revealed the presence of various sedatives, hypnotics, and antipsychotic drugs in blood, urine, and gastric content. Some of the compounds identified were determined at blood concentrations well above the known therapeutic concentrations: zolpidem (2.87 mg/L), bromazepam (2.39 mg/L), nordazepam (4.21 mg/L), and levopremazine (0.64 mg/L). Specific analysis of thiodicarb and of its methomyl metabolite was then performed on all fluids and tissues collected during autopsy by liquid chromatography ion trap tandem mass spectrometry (LC-MS-MS). The anticholinesterase capacity of blood, urine, and gastric content collected at autopsy was 83%, 82%, and 32%, respectively (normal value: 0%). The presence of thiodicarb in the bottle found near the body corroborates the hypothesis of an intake of that compound. Although thiodicarb was only detected in gastric content (24.3 mg/L), its methomyl metabolite was quantified in most postmortem tissues and fluids: gastric content (19.9 mg/L), peripheral blood (0.7 mg/L), urine (8.5 mg/L), bile (2.7 mg/L), liver (0.7 mg/kg), kidney (1.7 mg/kg), lung (1.5 mg/kg), brain (9.3 mg/kg), and heart (3.6 mg/kg).

Decomposition of water-soluble mononitrosyl iron complexes with dithiocarbamates and of dinitrosyl iron complexes with thiol ligands in animal organisms.

EPR studies have shown that water-soluble mononitrosyl iron complexes with N-methyl-d-glucamine dithiocarbamate (MNIC-MGD) (3 micromol) injected to intact mice were decomposed virtually completely within 1h. The total content of MNIC-MGD in animal urine did not exceed 30 nmol/ml. In the liver, a small amount of MNIC-MGD were converted into dinitrosyl iron complexes (30 nmol/g of liver tissue). The same was observed in intact rabbits in which MNIC-MGD formation was induced by endogenous or exogenous NO binding to NO traps, viz., iron complexes with MGD. In mice, the content of MNIC-MGD in urine samples did not change after bacterial lipopolysaccharide-induced expression of iNOS. It was supposed that MNIC-MGD decomposition in intact animals was largely due to the release of NO from the complexes and its further transfer to other specific acceptors. In mice with iNOS expression, the main contribution to MNIC-MGD decomposition was made by superoxide ions whose destructive effect is mediated by an oxidative mechanism. This effect could fully compensate the augmented synthesis of MNIC-MGD involving endogenous NO whose production was supported by iNOS. Water-soluble dinitrosyl iron complexes (DNIC) with various thiol-containing ligands and thiosulfate injected to intact mice were also decomposed; however, in this case the effect was less pronounced than in the case of MNIC-MGD. It was concluded that DNIC decomposition was largely due to the oxidative effect of superoxide ions on these complexes.

[Safety, biodistribution, and dosimetry of myocardial imaging agent 99Tc(m)N-NOET in healthy volunteers].

OBJECTIVE: To study the safety, biodistribution, and dosimetry of myocardial perfusion imaging agent 99Tc(m)N-NOET in 10 healthy volunteers. METHODS: 744-792 MBq of 99Tc(m)N-NOET was injected to each volunteer. Safety parameters and adverse event was measured in 24 hours of injection. Biodistribution was studied by whole-body imaging 1, 30 minutes, 1, 2, 4, 8, and 24 hours after the injection of 99Tc(m)N-NOET. The estimation of dosimetry was based on the standard medical internal radiation dose method using MIRDOSE 3.0 analysis program. Myocardial single photon emission computed tomography (SPECT) imaging was performed at 1 and 4 hours after injection. RESULTS: No undesirable effects were reported by the subject during 24 hours after injection of 99Tc(m)N-NOET. No clinically significant changes were found in vital signs (heart rate, blood pressure, and electrocardiogram). No biochemical aspects and serology changes were measured. The myocardial SPECT imaging was clear. Cardiac uptake of 99Tc(m)N-NOET was as high as 2.68% at 2 hours after injection. The heart to lung ratio was more than 1 from 30 minutes after injection, reaching a maximum of 1.91 +/- 0.53 at 2 hours after injection. Radiation dosimetry calculations indicated an effective absorbed dose of 1.28 x 10(-5) Sv/MBq. The dosimetry in each main organ is lower then 50 mGy given 740 MBq of 99Tc(m)N-NOET in once imaging. CONCLUSIONS: 99Tc(m)N-NOET exhibits high cardiac uptake and low estimated effective absorbed dose. It's a safe myocardial perfusion imaging agent.

The influence of activated carbon surface properties on the adsorption of the herbicide molinate and the bio-regeneration of the adsorbent.

In the present study, the effect of the textural and surface chemistry properties of the activated carbon were evaluated in a combined treatment system to remove the herbicide molinate from waters. The process consists of an initial adsorption step followed by the bio-regeneration of the activated carbon through the utilization of a defined bacterial mixed culture (DC), previously described as able to mineralize molinate. Molinate adsorption and partial bio-regeneration was favoured with activated carbons with larger pores, consisting mainly of meso and macropores. In order to study the effect of different surface chemical characteristics while maintaining the original textural properties, a commercial activated carbon was submitted to thermal and nitric acid treatments. The thermal treatment improved the molinate adsorption capacity of activated carbon. However, the bio-regeneration of the nitric acid oxidised activated carbon was slightly higher. With all the activated carbon materials used it was observed that the biological consumption of molinate present in the liquid phase displaced the equilibrium towards the activated carbon partial regeneration.

The in vivo cardiac kinetics of Tc-99m N-NOET are accelerated in obese, hyperlipidemic Zucker rats.

BACKGROUND: Previous studies demonstrated that the intrinsic myocardial washout of bis(N-ethoxy,N-ethyldithiocarbamato)nitrido technetium(V) (technetium 99m N-NOET) was affected by changes occurring in the intravascular compartment such as variations in circulating lipid levels. We sought to determine whether the myocardial kinetics of Tc-99m N-NOET were affected by hyperlipidemia in a clinically relevant experimental model. METHODS AND RESULTS: Tc-99m N-NOET (50 MBq/kg) and thallium 201 (12 MBq/kg) were injected intravenously into hyperlipidemic fa/fa Zucker rats (n=6) and their lean, normolipidemic littermates (n=8), and dual-isotope in vivo planar imaging was performed for 60 minutes. In vivo image quantification indicated significantly faster cardiac washout of Tc-99m N-NOET in fa/fa animals versus lean animals (time constant, 411+/-64 minutes vs 1094+/-226 minutes, respectively; P<.05), whereas Tl-201 cardiac washout was not affected (356+/-85 minutes vs 337+/-53 minutes, respectively; P=not significant). CONCLUSION: The cardiac kinetics of Tc-99m N-NOET, but not those of Tl-201, were accelerated after intravenous injection of the tracer in fa/fa Zucker rats with circulating lipid levels similar to those encountered clinically in hyperlipidemic patients. The relationship between lipidemia and the rate of Tc-99m N-NOET myocardial washout warrants further clinical investigation.

Toxicity and bioavailability of atrazine and molinate to the freshwater fish (Melanotenia fluviatilis) under laboratory and simulated field conditions.

Acute (96 h) semi-static toxicity tests were conducted by exposing the freshwater fish, Melanotenia fluviatilis, to atrazine and molinate in laboratory and river water both with and without sediment. The 96-h EC50 (imbalance) values of atrazine to M. fluviatilis ranged from 5.6 to 10.4 mg L(-1) while the corresponding values for molinate ranged from 7.9 to 14.8 mg L(-1), respectively. Atrazine was classed as having moderate toxicity while molinate had low to moderate toxicity to M. fluviatilis. Neither the presence of river water nor sediment significantly (P<0.05) reduced the bioavailability of either herbicide to M. fluviatilis. A series of other studies by the authors have found that sediment significantly (P<0.05) reduced the bioavailability of these two chemicals to a variety of organisms. Reasons for sediment having no effect for this species were examined. This lack of effect by sediment is most likely due to the relative rates of absorption into the fish and adsorption onto the sediment. However, contributions to this outcome by resuspended sediment, contaminated food and a combined effect of the herbicides and sediment could not be excluded.

Cellular uptake of (99m)TcN-NOET in human leukaemic HL-60 cells is related to calcium channel activation and cell proliferation.

PURPOSE: A major goal of nuclear oncology is the development of new radiolabelled tracers as proliferation markers. Intracellular calcium waves play a fundamental role in the course of the cell cycle. These waves occur in non-excitable tumour cells via store-operated calcium channels (SOCCs). Bis(N-ethoxy, N-ethyldithiocarbamato) nitrido technetium (V)-99m ((99m)TcN-NOET) has been shown to interact with L-type voltage-operated calcium channels (VOCCs) in cultured cardiomyocytes. Considering the analogy between VOCCs and SOCCs, we sought to determine whether (99m)TcN-NOET also binds to activated SOCCs in tumour cells in order to clarify the potential value of this tracer as a proliferation marker. METHODS: Uptake kinetics of (99m)TcN-NOET were measured in human leukaemic HL-60 cells over 60 min and the effect of several calcium channel modulators on 1-min tracer uptake was studied. The uptake kinetics of (99m)TcN-NOET were compared both with the variations of cytosolic free calcium concentration measured by indo-1/AM and with the variations in the SG2M cellular proliferation index. RESULTS: All calcium channel inhibitors significantly decreased the cellular uptake of (99m)TcN-NOET whereas the activator thapsigargin induced a significant 10% increase. In parallel, SOCC activation by thapsigargin, as measured using the indo-1/AM probe, was inhibited by nicardipine. These results indicate that the uptake of (99m)TcN-NOET is related to the activation of SOCCs. Finally, a correlation was observed between the tracer uptake and variations in the proliferation index SG2M. CONCLUSION: The uptake of (99m)TcN-NOET seems to be related to SOCC activation and to cell proliferation in HL-60 cells. These results indicate that (99m)TcN-NOET might be a marker of cell proliferation.

Effect of river water, sediment and time on the toxicity and bioavailability of molinate to the marine bacterium Vibrio fischeri (Microtox).

The toxicity and bioavailability of molinate to Vibrio fischeri (Microtox((R))) were determined in both laboratory and river water in the absence and presence of sediment after 0, 24, 48, 72 and 96-h exposure. The bioavailability of molinate, expressed as 5min EC50s (bioluminescence) and their fiducial limits calculated using initial measured concentrations, to V. fischeri in laboratory water in the absence and presence of sediment ranged from 1.8 (1.7-2.1) to 3.6 (3.5-3.7) mgL(-1) and 1.3 (1.2-1.4) to 4.2 (3.5-4.5) mgL(-1), respectively. The corresponding values in river water and river water plus sediment were 1.7 (1.6-1.8) to 3.8 (3.6-4.1) and 1.3 (1.3-1.4) to 4.6 (4.2-4.9) mgL(-1), respectively. River water did not significantly (P>0.05) reduce the bioavailability of molinate to V. fischeri compared to that of laboratory water. However, the presence of sediment significantly (P<0.05) reduced the bioavailability of molinate to V. fischeri in both waters. The exposure time also significantly (P<0.05) reduced the bioavailability of molinate to V. fischeri in both waters in the presence and absence of sediment. The type of water did not significantly (P>0.05) affect the loss of molinate during the 96-h exposure period. However, the presence of sediment significantly (P<0.01) increased the loss of molinate from the test solutions, probably by binding to the sediment particles. Exposure period and concentration levels significantly (P<0.05) affected the loss of the herbicides over the 96h.