Field Residues and Effects of the Insect Growth Regulator Novaluron and Its Major Co-Formulant N-Methyl-2-Pyrrolidone on Honey Bee Reproduction and Development.

Owing to the recent declines in honey bee (Apis mellifera L.) populations, there is a need for field and laboratory studies to investigate threats to pollinator health. This study examines the hypothesis that the organophosphate alternative, Rimon 0.83EC, can have consequences to honey bee health by combining newly acquired field residue data, laboratory bioassays, and colony level feeding studies. Following label rate applications of Rimon 0.83EC to apple trees, average residue concentrations of the active ingredient, novaluron, were found to be 3.38 ppm in tree-collected pollen. Residues of the major co-formulant in Rimon 0.83EC, N-methyl-2-pyrrolidone (NMP), were below the limit of detection in the field, but a growth chamber study described here found that NMP can persist in pollen for up to 7 d with average concentrations of 69.3 ppm. Concurrent larval rearing studies found novaluron and NMP to be toxic to developing honey bees at doses as low as 100 ppb and 100 ppm, respectively. Nucleus colony feeding studies found that chronic exposure to Rimon 0.83EC at doses as low as 200 ppm (18.6 ppm novaluron) can result in interruptions to brood production that can last for up to 2 wk after exposure. Taken together, these data indicate the use of Rimon 0.83EC on blooming flowers is a significant threat to honey bee reproduction, and suggest the need for more strict and clear usage guidelines.

Analysis of possible genotoxicity of the herbicide flurochloridone and its commercial formulations: Endo III and Fpg alkaline comet assays in Chinese hamster ovary (CHO-K1) cells.

Cytotoxic and genotoxic effects of flurochloridone (FLC) and its formulations Twin Pack Gold(®) and Rainbow(®) were evaluated in CHO-K1 cells. Using the alkaline single-cell gel electrophoresis (SCGE) assay, we observed that FLC (15 µg/ml), Twin Pack Gold(®) or Rainbow(®) induced primary DNA damage, increasing the frequency of damaged nucleoids. Vitamin E pretreatment did not modify the effect. Decreased cell viability was observed only in Twin Pack Gold(®)-treated cultures and was significantly ameliorated by vitamin E. Post-treatment of herbicide-damaged CHO-K1 cells with the enzymes Endo III or Fpg did not increase FLC-, Twin Pack Gold(®)-, or Rainbow(®)-induced DNA damage. These results demonstrate that neither FLC nor FLC-based formulations induce DNA damage through hydroxyl radical or lipid alkoxyl radical production, and that the induced DNA lesions were not related to oxidative damage at the purine/pyrimidine level. Our observations strongly suggest that the cytotoxic effects observed after Twin Pack Gold(®) exposure are due to the excipients contained within the technical formulation rather than FLC itself.

Preclinical pharmacokinetic and toxicological evaluation of MIF-1 peptidomimetic, PAOPA: examining the pharmacology of a selective dopamine D2 receptor allosteric modulator for the treatment of schizophrenia.

Schizophrenia is a mental illness characterized by a breakdown in cognition and emotion. Over the years, drug treatment for this disorder has mainly been compromised of orthosteric ligands that antagonize the active site of the dopamine D2 receptor. However, these drugs are limited in their use and often lead to the development of adverse movement and metabolic side effects. Allosteric modulators are an emerging class of therapeutics with significant advantages over orthosteric ligands, including an improved therapeutic and safety profile. This study investigates our newly developed allosteric modulator, PAOPA, which is a specific modulator of the dopamine D2 receptor. Previous studies have shown PAOPA to attenuate schizophrenia-like behavioral abnormalities in preclinical models. To advance this newly developed allosteric drug from the preclinical to clinical stage, this study examines the pharmacokinetic behavior and toxicological profile of PAOPA. Results from this study prove the effectiveness of PAOPA in reaching the implicated regions of the brain for therapeutic action, particularly the striatum. Pharmacokinetic parameters of PAOPA were found to be comparable to current market antipsychotic drugs. Necropsy and histopathological analyses showed no abnormalities in all examined organs. Acute and chronic treatment of PAOPA indicated no movement abnormalities commonly found with the use of current typical antipsychotic drugs. Moreover, acute and chronic PAOPA treatment revealed no hematological or metabolic abnormalities classically found with the use of atypical antipsychotic drugs. Findings from this study demonstrate a better safety profile of PAOPA, and necessitates the progression of this newly developed therapeutic for the treatment of schizophrenia.

Genotoxic and cytotoxic evaluation of the herbicide flurochloridone on Chinese hamster ovary (CHO-K1) cells.

The in vitro effects of flurochloridone (FLC) and its formulations Twin Gold Pack® (25% a.i.) and Rainbow® (25% a.i.) were evaluated on Chinese hamster ovary (CHO-K1) cells by genotoxicity [sister chromatid exchange (SCE)] and cytotoxicity [cell-cycle progression, proliferative rate index (PRI), mitotic index (MI), MTT, and neutral red] end points. Cells were treated for 24h within the 0.25-15µg/ml concentration range. FLC and Twin Pack Gold® induced a significant and equivalent increase in SCEs regardless of the concentration. Rainbow®-induced SCEs at concentrations higher than 2.5µg/ml; however, the increases were always lower than those induced by FLC and Twin Pack Gold®. For all compounds, the PRI decreased as a function of the concentration titrated into cultures. Whereas only the highest FLC and Twin Pack Gold® concentrations induced a significant reduction of the MI, all tested Rainbow® concentrations induced MI inhibition. Overall, the results demonstrated that although all compounds were not able to reduce the lysosomal activity, the mitochondrial activity was diminished when the highest concentrations were employed. These observations represent the first study analyzing the genotoxic and cytotoxic effects exerted by FLC and two formulated products on mammalian cells in vitro, at least on CHO-K1 cells.

Cytotoxic and HLE-inhibitory tetramic acid derivatives from marine-derived fungi.

Tetramic acid derivatives are an important class of nitrogen heterocycles with a pyrrolidine-2,4-dione core as a key structural motif. From the sponge-derived fungus Beauveria bassiana, a new equisetin-like tetramic acid derivative, beauversetin (1), was isolated. The sea weed-derived fungus Microdiplodia sp. produced the tetramic acid derivative 2 (Sch210972) which was shown to inhibit human leucocyte elastase (HLE) with an IC50 of 1.04 microg mL(-1).

[Secondary effects associated with raltegravir]. / Efectos secundarios asociados al raltegravir.

Integrase inhibitors are a new therapeutic modality against HIV. Raltegravir is the first integrase inhibitor to have been approved by the health authorities for human use. This drug acts by inhibiting the HIV enzyme that catalyzes integration of the virus inside the genome of the host cell. In the host cell, there is no homologue to viral integrase and consequently the potential toxicity of this drug is probably low. The results of safety studies in animal models have shown that the recommended dose in humans is lower than the dose below which no secondary effects are observed. Studies of genotoxicity and carcinogenicity, as well as of fertility and embryo development, have been negative to date. During clinical trials, raltegravir has been shown to have a very good safety profile, with few adverse effects, which were mild-to-moderate and similar to those of the comparator. The most notable were diarrhea, nausea and headache. The lipid profile of raltegravir was better than that of efavirenz. In view of the above, the risk-benefit ratio for raltegravir is positive.

Comprehensive evaluation of canine renal papillary necrosis induced by nefiracetam, a neurotransmission enhancer.

The effects of nefiracetam, a neurotransmission enhancer, on renal biochemistry and morphology with toxicokinetic disposition were investigated in both in vivo and in vitro systems. In the in vivo studies with rats, dogs, and monkeys, only the dog exhibited renal papillary necrosis. Namely, when beagle dogs were orally administered with 300 mg/kg/day of nefiracetam over 11 weeks, decreased urinary osmotic pressure was noted from week 5, followed by increases in urine volume and urinary lactate dehydrogenase from week 8. The first morphological change was necrosis of ductal epithelia in the papilla in week 8. In toxicokinetics after 3 weeks of repeated oral administration to dogs, nefiracetam showed somewhat high concentrations in serum and the renal papilla as compared with rats and monkeys. As for metabolites, although metabolite-18 (M-18) concentration in the renal papilla of dogs was between that in rats and monkeys, the concentration ratios of M-18 in the papilla to cortex and papilla to medulla were remarkably high. In the in vitro studies, while nefiracetam itself showed no effects on the synthesis of prostaglandin E2 and 6-keto-prostaglandin F1alpha, a stable metabolite of prostaglandin I2, in canine renal papillary slices, only M-18 among the metabolites clearly decreased both prostaglandin syntheses. The basal prostaglandin synthesis in canine renal papillary slices was extremely low relative to those in rats and monkeys. Taken together, certain factors such as basal prostaglandin synthesis, M-18 penetration into the renal papilla leading to an intrarenal gradient, and inhibitory potential of M-18 on prostaglandin synthesis were considered to be crucial for the occurrence of renal papillary necrosis in dogs.

Phytotoxicity of the tetramic acid metabolite trichosetin.

Trichosetin, a tetramic acid-containing metabolite produced in the dual culture of Trichoderma harzianum and Catharanthus roseus (L.) G. Don callus, was subjected to phytotoxicity assays. In seedling growth assays, trichosetin inhibited root and shoot growth of all five plant species tested by damaging the cell membrane, as evidenced by the dose-dependent increase in electrolyte leakage and lipid peroxidation. Vital staining of trichosetin-treated Nicotiana tabacum BY-2 cells, with rhodamine 123, showed a weaker green fluorescence compared to controls indicating damaging effects on mitochondria. FDA-PI staining, to determine cell viability, indicated that cells of the trichosetin-treated roots were mostly dead.

FK960 [N-(4-acetyl-1-piperazinyl)-p-fluorobenzamide monohydrate], a novel potential antidementia drug, restores the regional cerebral blood flow response abolished by scopolamine but not by HA-966: a positron emission tomography study with unanesthetized rhesus monkeys.

The interactions of FK960 [N-(4-acetyl-1-piperazinyl)-p-fluorobenzamide monohydrate], a novel potential antidementia drug, with cholinergic and glutamatergic neuronal systems were evaluated with respect to its effects on the regional cerebral blood flow (rCBF) response to vibrotactile stimulation in unanesthetized rhesus monkeys with [15O]H2O and high resolution positron emission tomography (PET). Under a saline condition, the vibrotactile stimulation given on the right forepaw induced a significant increase in the rCBF response in the contralateral somatosensory cortex of the monkey brain. Systemic administration of scopolamine (50 microg/kg, i.v.), a muscarinic cholinergic receptor antagonist, completely abolished the rCBF response to the stimulation, and the abolishment lasted, at least, up to 4 h after scopolamine injection. The scopolamine-induced abolishment of rCBF response was restored by the administration of FK960 at relatively wide dosing range from 1 to 1000 microg/kg (i.v. ), and the recovery by FK960 on the rCBF response lasted for 1 h following the administration of FK960 at doses of 100 and 1000 microg/kg. On the other hand, the rCBF response abolished by 1000 microg/kg of (+)-3-amino-1-hydroxy-2-pyrrolidone (HA-966), an antagonist of the glycine modulatory site on the N-methyl-d-aspartate (NMDA) receptors, was not restored by FK960 (1000 microg/kg, i.v.). These findings suggest that FK960 reverses the abolished rCBF response to somatosensory stimulation via enhancement of cholinergic neurotransmission but not via the glutamatergic one.

Fifty-two-week oral toxicity study of the new cognition-enhancing agent nefiracetam in rats.

A 52-week toxicity study by oral gavage administration was performed in Sprague-Dawley rats with nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide, DM-9384, CAS 77191-36-7), a new cognition-enhancing agent, as a part of a safety evaluation program. Dosages of 0 (control), 10, 30, 100 and 300 mg/kg/d were selected for this study. Treatment-related findings were confined to the 300 mg/kg/d level and, to a lesser extent, the 100 and 30 mg/kg/d levels, with the investigations indicating the kidney as the main target organ for toxicity. The microscopic pathology examination of this organ showed papillary epithelial hyperplasia and/or collecting duct epithelial hyperplasia, with cortical scarring and occasional mineralisation in the papilla. Histopathological changes in the liver, centrilobullar hepatocyte enlargement (accompanied by fine vacuolation) and foci/areas of eosinophilic hepatocytes were considered to reflect the induction of drug-metabolising enzymes in the liver. Other tissues showing treatment-related findings included the salivary glands, urinary bladder, spleen, pancreas and adrenals. Additionally, other notable findings included (in the high dosage males only) a decline in body weight (from week 34), lower erythrocytic characteristics and slightly higher plasma urea nitrogen and alkaline phosphatase values. The results in this study, therefore, indicated that the non-toxic effect level was 10 mg/kg/d of nefiracetam.

Oncogenicity studies of the cognition-enhancing agent nefiracetam in mice and rats.

Oncogenicity studies of nefiracetam (N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide, DM-9384, CAS 77191-36-7), a new cognition-enhancing agent, were carried out in male and female mice and rats. The compound was administered in diet for 104 weeks at dosage levels of 30, 90 and 270 mg/kg/d for mice and of 200, 600 and 1800 ppm for rats. The administration of nefiracetam produced no effects on survival, appearance or behavior. Body weights of the high dose male mice and rats were occasionally significantly decreased when compared to the controls. When calculated on a g/animal/d basis, food consumption was sometimes decreased for these male groups. At necropsy, there was no evidence of treatment related changes, nor were these seen on histopathological examination. All microscopic changes seen in mice and rats were of the usual type commonly occurring in untreated aged B6C3F1 mice and F344 rats. In conclusion, the administration of nefiracetam for 24 months to B6C3F1 mice and F344/DuCrj rats produced only slight effects on body weight in the high dose males with a no-effect level of 90 mg/kg/d for mice or 600 ppm for rats. There was no evidence of an oncogenic effect of nefiracetam.