Differences in Small Plot and On-Farm Trials for Yield Response to Foliar Fungicide in Soybean

Soybean yield response variability to foliar fungicide applications was evaluated in on-farm replicated strip trials (OFTs) and small-plot trials (SPTs) from 2008 through 2015 in Iowa. A total of 230 OFTs and 49 SPTs were compared for yield response to pyraclostrobin, pyraclostrobin + fluxapyroxad, or trifloxystrobin + prothioconazole fungicides. OFTs (18 to 55 m wide and 200 to 800 m long strips) were harvested with farmers' combines equipped with yield monitors and GPS, while SPTs (3.0 to 4.6 m wide and 10.7 to 15.3 m long plots) were harvested by small research plot combines. Variance component and power analyses were conducted with a subset of data consisting of 12 OFTs and SPTs, each with pyraclostrobin and evaluated in 2008 and 2009. While average yield responses were similar, the residual random yield variation was smaller in OFTs than SPTs. Power analysis showed that SPTs need more replications than OFTs to detect the same overall treatment differences. To detect a yield response of 134 kg/ha, it would require at least three treatment replications with 12 locations in OFTs and seven replications with 12 locations in SPTs. Researchers need to acknowledge the differences in statistical power of detecting yield responses to foliar fungicide on soybean in different types of field experiments, especially with smaller plot sizes in situations with less foliar disease.

Potential Threats Posed by New or Emerging Marine Biotoxins in UK Waters and Examination of Detection Methodologies Used for Their Control: Cyclic Imines

Cyclic imines (CIs) are a group of phytoplankton produced toxins related to shellfish food products, some of which are already present in UK and European waters. Their risk to shellfish consumers is poorly understood, as while no human intoxication has been definitively related to this group, their fast acting toxicity following intraperitoneal injection in mice has led to concern over their human health implications. A request was therefore made by UK food safety authorities to examine these toxins more closely to aid possible management strategies. Of the CI producers only the spirolide producer Alexandrium ostenfeldii is known to exist in UK waters at present but trends in climate change may lead to increased risk from other organisms/CI toxins currently present elsewhere in Europe and in similar environments worldwide. This paper reviews evidence concerning the prevalence of CIs and CI-producing phytoplankton, together with testing methodologies. Chemical, biological and biomolecular methods are reviewed, including recommendations for further work to enable effective testing. Although the focus here is on the UK, from a strategic standpoint many of the topics discussed will also be of interest in other parts of the world since new and emerging marine biotoxins are of global concern.

OKN-007 decreases free radical levels in a preclinical F98 rat glioma model

Free radicals are associated with glioma tumors. Here, we report on the ability of an anticancer nitrone compound, OKN-007 [Oklahoma Nitrone 007; a disulfonyl derivative of α-phenyl-tert-butyl nitrone (PBN)] to decrease free radical levels in F98 rat gliomas using combined molecular magnetic resonance imaging (mMRI) and immunospin-trapping (IST) methodologies. Free radicals are trapped with the spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), to form DMPO macromolecule radical adducts, and then further tagged by immunospin trapping by an antibody against DMPO adducts. In this study, we combined mMRI with a biotin-Gd-DTPA-albumin-based contrast agent for signal detection with the specificity of an antibody for DMPO nitrone adducts (anti-DMPO probe), to detect in vivo free radicals in OKN-007-treated rat F98 gliomas. OKN-007 was found to significantly decrease (P < 0.05) free radical levels detected with an anti-DMPO probe in treated animals compared to untreated rats. Immunoelectron microscopy was used with gold-labeled antibiotin to detect the anti-DMPO probe within the plasma membrane of F98 tumor cells from rats administered anti-DMPO in vivo. OKN-007 was also found to decrease nuclear factor erythroid 2-related factor 2, inducible nitric oxide synthase, 3-nitrotyrosine, and malondialdehyde in ex vivo F98 glioma tissues via immunohistochemistry, as well as decrease 3-nitrotyrosine and malondialdehyde adducts in vitro in F98 cells via ELISA. The results indicate that OKN-007 effectively decreases free radicals associated with glioma tumor growth. Furthermore, this method can potentially be applied toward other types of cancers for the in vivo detection of macromolecular free radicals and the assessment of antioxidants.

A Txnrd1-dependent metabolic switch alters hepatic lipogenesis, glycogen storage, and detoxification

Besides helping to maintain a reducing intracellular environment, the thioredoxin (Trx) system impacts bioenergetics and drug metabolism. We show that hepatocyte-specific disruption of Txnrd1, encoding Trx reductase-1 (TrxR1), causes a metabolic switch in which lipogenic genes are repressed and periportal hepatocytes become engorged with glycogen. These livers also overexpress machinery for biosynthesis of glutathione and conversion of glycogen into UDP-glucuronate; they stockpile glutathione-S-transferases and UDP-glucuronyl-transferases; and they overexpress xenobiotic exporters. This realigned metabolic profile suggested that the mutant hepatocytes might be preconditioned to more effectively detoxify certain xenobiotic challenges. Hepatocytes convert the pro-toxin acetaminophen (APAP, paracetamol) into cytotoxic N-acetyl-p-benzoquinone imine (NAPQI). APAP defenses include glucuronidation of APAP or glutathionylation of NAPQI, allowing removal by xenobiotic exporters. We found that NAPQI directly inactivates TrxR1, yet Txnrd1-null livers were resistant to APAP-induced hepatotoxicity. Txnrd1-null livers did not have more effective gene expression responses to APAP challenge; however, their constitutive metabolic state supported more robust GSH biosynthesis, glutathionylation, and glucuronidation systems. Following APAP challenge, this effectively sustained the GSH system and attenuated damage.

Nitrone-based therapeutics for neurodegenerative diseases: their use alone or in combination with lanthionines

The possibility of free radical reactions occurring in biological processes led to the development and employment of novel methods and techniques focused on determining their existence and importance in normal and pathological conditions. For this reason the use of nitrones for spin trapping free radicals became widespread in the 1970s and 1980s, when surprisingly the first evidence of their potent biological properties was noted. Since then widespread exploration and demonstration of the potent biological properties of phenyl-tert-butylnitrone (PBN) and its derivatives took place in preclinical models of septic shock and then in experimental stroke. The most extensive commercial effort made to capitalize on the potent properties of the PBN-nitrones was for acute ischemic stroke. This occurred during 1993-2006, when the 2,4-disulfonylphenyl PBN derivative, called NXY-059 in the stroke studies, was shown to be safe in humans and was taken all the way through clinical phase 3 trials and then was deemed to be ineffective. As summarized in this review, because of its excellent human safety profile, 2,4-disulfonylphenyl PBN, now called OKN-007 in the cancer studies, was tested as an anti-cancer agent in several preclinical glioma models and shown to be very effective. Based on these studies this compound is now scheduled to enter into early clinical trials for astrocytoma/glioblastoma multiforme this year. The potential use of OKN-007 in combination with neurotropic compounds such as the lanthionine ketamine esters is discussed for glioblastoma multiforme as well as for various other indications leading to dementia, such as aging, septic shock, and malaria infections. There is much more research and development activity ongoing for various indications with the nitrones, alone or in combination with other active compounds, as briefly noted in this review.

Protease-activated receptor-1 inhibitors: a novel class of antiplatelet agents for the treatment of patients with acute coronary syndrome

The unifying basis of acute coronary syndrome (ACS) is the complication of a vulnerable coronary plaque, an event primarily mediated by platelet activation. Three major pathways are predominantly involved in this process: thromboxane A(2) via the thromboxane A(2) receptor, adenosine diphosphate via the P2Y(12) receptor, and thrombin via the protease-activated receptor (PAR)-1, with the latter being the most potent platelet activator. Despite the effective inhibition of the first two pathways with aspirin and an expanding family of P2Y(12) inhibitors, respectively, the recurrence of ischemic events in patients with ACS remains high. There is also a growing concern regarding the safety profile in terms of bleeding with more powerful antiplatelet agents, which has tempered expectations of newly developed compounds. PAR-1 inhibitors are a novel class of antiplatelet agents that inhibit thrombin-mediated platelet activation. Preliminary data indicate that these compounds have the potential to improve ischemic prognosis without increasing the bleeding risk. In this chapter we will discuss the rationale for developing this novel class of antiplatelet agents and specifically, the two compounds in most advanced clinical development, vorapaxar and atopaxar.

Oral administration of the thrombin receptor antagonist E5555 (atopaxar) attenuates intimal thickening following balloon injury in rats

Thrombin is a powerful agonist for a variety of cellular responses including platelet aggregation and vascular smooth muscle cell (SMC) proliferation. These actions are mediated by a thrombin receptor known as protease-activated receptor-1 (PAR-1). Recently we discovered that 1-(3-tert-butyl-4-methoxy-5-morpholinophenyl)-2-(5,6-diethoxy-7-fluoro-1-imino-1,3-dihydro-2H-isoindol-2-yl)ethanone hydrobromide (E5555, atopaxar) is a potent and selective thrombin receptor antagonist. This study characterized the pharmacological effects of E5555 on SMC proliferation in vitro and in a rat model of intimal thickening after balloon injury in vivo. E5555 selectively inhibited rat aortic SMC proliferation induced by thrombin and thrombin receptor-activating peptide (TRAP) with half maximal inhibitory concentration (IC(50)) values of 0.16 and 0.038 μM, respectively. E5555 did not inhibit rat SMC proliferation induced by basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) at concentrations up to 1μM. In addition, E5555 inhibited human aortic SMC proliferation induced by thrombin at concentrations of 0.3 and 3units/ml with IC(50) values of 0.028 and 0.079 μM, respectively, whereas it did not affect bFGF-induced proliferation at concentrations up to 1μM. Repeated oral administration of 30 mg/kg E5555 (once daily for 16 days) significantly reduced neointimal formation in the balloon-injured rat arterial model. These results suggested that a PAR-1 antagonist could be effective for treating restenosis following vascular intervention in addition to preventing thrombus formation. E5555 could thus have therapeutic potential for restenosis and chronic atherothrombotic disease.

Controlled release of anti-inflammatory siRNA from biodegradable polymeric microparticles intended for intra-articular delivery to the temporomandibular joint

PURPOSE

As the next step in the development of an intra-articular controlled release system to treat painful temporomandibular joint (TMJ) inflammation, we developed several biodegradable poly(DL-lactic-co-glycolic acid) (PLGA)-based microparticle (MP) formulations encapsulating a model anti-inflammatory small interfering RNA (siRNA) together with branched poly(ethylenimine) (PEI) as a transfecting agent. The effect of siRNA loading and N:P ratio on the release kinetics of siRNA-PEI polyplexes was determined, and the size and N:P ratio of the polyplexes released over time was characterized.

METHODS

Polyplex-loaded PLGA MPs were prepared using an established double emulsion technique. Increasing the pH of the release samples enabled siRNA-PEI dissociation and subsequent measurement of the release of each component over 28 days. Polyplex diameter was measured for all release samples and compared to freshly prepared siRNA-PEI under simulated physiologic conditions.

RESULTS

Systematic variation of siRNA loading and N:P ratio resulted in distinct siRNA and PEI release profiles. Polyplex diameter remained constant despite large variations in the relative amounts of siRNA and PEI. Excess PEI was sequestered through complexation with 500-1,000 nm diameter PLGA MP-derived particles, including small MPs and PLGA degradation products.

CONCLUSIONS

These PLGA MP formulations show exciting potential as the first intra-articular TMJ controlled release system.

The encapsulation and intracellular delivery of trehalose using a thermally responsive nanocapsule

The thermally responsive wall permeability of an empty core-shell structured Pluronic nanocapsule (together with its temperature dependent size and surface charge) was successfully utilized for encapsulation, intracellular delivery, and controlled release of trehalose, a highly hydrophilic small (M(W) = 342 D) molecule (a disaccharide of glucose) that is exceptional for long-term stabilization of biologicals (particularly at ambient temperatures). It was found that trehalose can be physically encapsulated in the nanocapsule using a soaking-freeze-drying-heating procedure. The nanocapsule is capable of physically withholding trehalose with negligible release in hours for cellular uptake at 37 degrees C when its wall permeability is low. A quick release of the encapsulated sugar can be achieved by thermally cycling the nanocapsule between 37 and 22 degrees C (or lower). A significant amount of trehalose (up to 0.3 M) can be delivered into NIH 3T3 fibroblasts by incubating the cells with the trehalose-encapsulated nanocapsules at 37 degrees C for 40 min. Moreover, cytotoxicity of the nanocapsule for the purpose of intracellular delivery of trehalose was found to be negligible. Altogether, the thermally responsive nanocapsule is effective for intracellular delivery of trehalose, which is critical for the long-term stabilization of mammalian cells at ambient temperatures and the eventual success of modern cell-based medicine.

Novel Orbital Shake Bioreactors for Transient Production of CHO Derived IgGs

Large-scale transient gene expression in mammalian cells is being developed for the rapid production of recombinant proteins for biochemical and preclinical studies. Here, the scalability of transient production of a recombinant human antibody in Chinese hamster ovary (CHO) cells was demonstrated in orbitally shaken disposable bioreactors at scales from 50 mL to 50 L. First, a small-scale multiparameter approach was developed to optimize the poly(ethylenimine)-mediated transfection in 50 mL shake tubes. This study confirmed the benefit, both in terms of extended cell culture viability and increased product yield, of mild hypothermic cultivation conditions for transient gene expression in CHO cells. Second, the scalability of the process was demonstrated in disposable shake bioreactors having nominal volumes of 5, 20, and 50 L with final antibody yields between 30 and 60 mg L(-1). Thus, the combination of transient gene expression with disposable shake bioreactors allows for rapid and cost-effective production of recombinant proteins in CHO cells.

Mucosal priming with PEI/DNA complex and systemic boosting with recombinant TianTan vaccinia stimulate vigorous mucosal and systemic immune responses

An effective vaccine strategy for HIV-1 will probably requires the induction and maintenance of both humoral and cellular immunity. We tested a new prime-boost approach of intranasal priming with 10 microg DNA plasmid in the PEI/DNA complexes and boosting with 10(7)PFU of replicative recombinant TianTan vaccinia virus (rTTV) expressing HIV-1 Gag in BALB/c mice. Intranasal priming with PEI/DNA complexes elicited strikingly stronger HIV-specific T-cell (p=0.0358) and IgA immune responses at mucosal sites of lung (p=0.0445) and vaginal tract (p=0.0469) than intranasal priming with naked DNA, though both are followed by the same rTTV boosting. Furthermore, an intramuscular boosting with rTTV could profoundly enhance both T-cell and antibody immune responses raised by intranasal priming. These results demonstrate that the combination of intranasal priming with PEI/DNA complexes and systemic boosting with rTTV is a preferable regimen for induction of both T-cell and humoral immune responses.

Uptake characteristics of NGR-coupled stealth PEI/pDNA nanoparticles loaded with PLGA-PEG-PLGA tri-block copolymer for targeted delivery to human monocyte-derived dendritic cells

We have investigated the in vitro uptake, toxicity, phenotypic consequences and transfection efficiency of a stealth NGR/PEG/PDBA-coupled-SHA-PEI/pDNA targeting polyplex loaded with PLGA-PEG-PLGA tri-block copolymer in human monocyte-derived dendritic cells (DCs). Modification with PEG effectively shielded and reduced non-specific phagocytosis by immature DCs to approximately 20%. Coupling the NGR cell-specific peptide to the PEGylated polyplex (NGR/PEG/PDBA-SHA-PEI/pDNA) however resulted in specific and enhanced phagocytosis in DCs without any observable toxicity at the optimum concentration of 0.25% of the copolymer. DNase treatment had no effect on DNA integrity in the encapsulated polyplex. Confocal microscopy confirmed intracellular localization of the targeting NGR/PEG/PDBA-SHA-PEI/pDNA microparticles, resulting in more enhanced uptake of the radiolabeled plasmid DNA and approximately 5- and 10-fold increase over the control tri-block Pluronic F68 copolymer and the non-targeting polyplex, respectively. More importantly, phagocytosis of the targeting microparticles neither altered the functionality of immature DCs nor the phenotypic expression of DC-specific cell surface molecules, CD80, CD86, CD40 and CD54 (ICAM-1), suggesting that uptake of the targeting microparticles by themselves did not induce DC maturation. Taken together, these results suggest that PLGA-PEG-PLGA encapsulation of this stealth targeting polyplex has no negative effects on key properties of immature DCs and should pave the way for targeting DCs for vaccination purposes.

PEI-alginate nanocomposites as efficient in vitro gene transfection agents

The positive charge on PEI was partially shielded by forming ionic nanocomposites with a polysaccharide, alginic acid, in aqueous solution, bypassing tedious chemical synthesis. The content of alginic acid was varied systematically to obtain a series of nanocomposites. The nanocomposites were first characterized by assessing the surface charge (zeta potential), size (DLS) and morphology (AFM) followed by evaluation for their DNA interaction ability, cytotoxicity and transfection efficiency on various cell lines. The transfection efficiency of PEI-alginate (6.26%) nanocomposites improved dramatically (2-16-fold over native PEI) in all the cell lines studied. However, a decrease in transfection efficiency was observed on deviating from this optimal concentration of alginic acid in nanocomposites. Cytotoxicity of PEI-alginate/DNA complexes was nearly abolished on increasing the concentration of alginic acid in nanocomposites. PEI-alginate (6.26%) nanocomposites also delivered SiRNAs efficiently into mammalian cells, resulting in 80% suppression of GFP expression. The cellular uptake and endosomal escape of PEI-alginate nanocomposites and PEI were found to follow a similar route when transfection was carried out in presence of chloroquine, bafilomycin A1, cytochalasin B and methyl-beta-cyclodextrin. The results demonstrate a versatile vector that can be used for efficient cytoplasmic delivery of a broad range of nucleic acids.

Inhibition of inducible nitric oxide synthase attenuates platelet adhesion in subpleural arterioles caused by lung ischemia-reperfusion in rabbits

Oxidative stress, induced by lung ischemia-reperfusion, leads to platelet and leukocyte activation and may contribute to decreased alveolar perfusion by platelet adhesion to the arteriolar wall. We investigated the hypothesis that ischemia-reperfusion injury increases inducible nitric oxide synthase (iNOS) activity and subsequent generation of reactive nitrogen species with P-selectin-dependent platelet-endothelial interactions and vasoconstriction during lung reperfusion. Subpleural arterioles, labeled platelets, and leukocytes were examined in anesthetized, open-chest rabbits by intravital fluorescence microscopy. Ischemia was caused by reversible occlusion of the right pulmonary artery for 1 or 2 h (1IR and 2IR groups). During 2 h of reperfusion, postischemic platelet rolling and adhesion were independent from leukocyte-arteriolar wall interactions and correlated with pulmonary arteriolar constriction in proportion to the length of ischemia. In rabbits treated with an iNOS inhibitor (1400W) before occlusion (2IR + 1400W group), platelet-arteriolar wall interactions and vasoconstriction were prevented. iNOS expression and activity in ischemic lung tissue were markedly greater than control and also were proportional to ischemia duration. NOS activity, immunochemically detected P-selectin, and nitrotyrosine expression in ischemic lung tissue from animals subjected to ischemia-reperfusion, as well as the plasma level of soluble P-selectin, were significantly higher than in nonischemic lungs and were inhibited by pretreatment with 1400W. These results show that platelet adhesion and arteriolar constriction during early reperfusion in the ventilated lung can result from increased iNOS activity and is highly correlated with reactive nitrogen species and P-selectin expression.

[PEI-PMMA cationic nanoparticles as carriers for gene transfer]

AIM

To investigate the properties of cationic nanoparticles composed of poly (ethyleneimine)-g-poly (methyl methacrylate) (PEI-PMMA) as gene delivery carriers and explore the mechanism of PEI-PMMA nanoparticles mediated gene transfer.

METHODS

PEI-PMMA nanoparticles were synthesized by free radical polymerization. The morphology of nanoparticles was observed by scanning electron microscopy. The particle size and zeta potential were measured by zeta sizer. The complex between pGL3 plasmid and nanoparticles was analyzed by gel electrophoresis; and PEI-PMMA nanoparticles mediated gene transfer into HeLa cells was observed by confocal laser scanning microscopy.

RESULTS

PEI-PMMA nanoparticles are spherical shape and monodispersity. The particle size and zeta potential are 172 nm and +50.3 mV, respectively. When pGL3 plasmid complexed with nanoparticles at N/P ratio of 5: 1 and 20: 1, the particle size of pGL3/nanoparticle complex are 133 and 139 nm and zeta potential is + 21.4 and + 33.7 mV, respectively. pGL3 plasmid complexed with nanoparticles completely at N/P ratio of 5: 1. PEI-PMMA nanoparticles can deliver pGL3 plasmid into HeLa cells by endocytosis and release pGL3 into the cytosol.

CONCLUSION

PEI-PMMA nanoparticles effectively transferred DNA to target cells and it is a promising non-viral carrier for gene delivery.

Acute toxicity of gymnodimine to mice

The acute toxicity of the phycotoxin gymnodimine to female Swiss mice by intraperitoneal injection and by oral administration has been determined. Gymnodimine was highly toxic by injection, the LD50 being only 96 microg/kg. Animals either died within 10 min of injection or made a full recovery with no perceptible long-term effects. Gymnodimine was also toxic after oral administration by gavage (LD50 755 microg/kg), but was much less toxic when administered with food. No signs of toxicity were seen in mice voluntarily ingesting food containing gymnodimine at a level sufficient to give a dose of approximately 7500 microg/kg. Pre-treatment with physostigmine or neostigmine protected against injected gymnodimine, suggesting that the latter exerts its toxic effects via blockade of nicotinic receptors at the neuromuscular junction. The low toxicity of gymnodimine when ingested with food suggests that this compound is of low risk to humans, a conclusion that is consonant with anecdotal evidence for the absence of harmful effects in individuals consuming shellfish contaminated with gymnodimine.

The lower-generation polypropylenimine dendrimers are effective gene-transfer agents

OBJECTIVE

To evaluate polypropylenimine dendrimers (generations 1-5: DAB 4, DAB 8, DAB 16, DAB 32, and DAB 64) as gene delivery systems.

METHODS

DNA binding was evaluated by measuring the reduced fluorescence of ethidium bromide, and molecular modelling of dendrimer-DNA complexes also was performed. Cell cytotoxicity was evaluated against the A431 cell line using the MTT assay. In vitro transfection was evaluated against the A431 cell line using the beta-galactosidase reporter gene and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium methylsulphate (DOTAP) served as a positive control.

RESULTS

Molecular modeling and experimental data revealed that DNA binding increased with dendrimer generation. Cell cytotoxicity was largely generation dependent, and cytotoxicity followed the trend DAB 64 > DAB 32 > DAB 16 > DOTAP > DAB 4 > DAB 8, whereas transfection efficacy followed the trend DAB 8 = DOTAP = DAB 16 > DAB 4 > DAB 32 = DAB 64.

CONCLUSION

The generation 2 polypropylenimine dendrimer combines a sufficient level of DNA binding with a low level of cell cytoxicity to give it optimum in vitro gene transfer activity.

Pharmacodynamic profile of the M1 agonist talsaclidine in animals and man

In functional pharmacological assays, talsaclidine has been described as a functionally preferential M1 agonist with full intrinsic activity, and less pronounced effects at M2- and M3 receptors. In accordance with this, cholinomimetic central activation measured in rabbits by EEG recordings occurred at a 10 fold lower dose than that inducing predominantly M3-mediated side effects. This pharmacological profile is also reflected in the clinical situation: Both in healthy volunteers and in Alzheimer patients--unlike after unspecific receptor stimulation through cholinesterase inhibitors--the mainly M3-mediated gastrointestinal effects (like nausea and vomiting) were not dose-limiting. Rather, sweating and hypersalivation, mediated through muscarinic receptors, occurred dose-dependently and were finally dose-limiting. In contrast to talsaclidine, sabcomeline had a less pronounced functional M1 selectivity in pharmacological assays. This was also shown in anaesthetized guinea pigs where sabcomeline alone induced bronchoconstriction, and in the rabbit EEG where central activation and cholinergic side effects occurred in the same dose range. Neither drug, however, showed convincing improvement of cognitive functions in patients with mild-to-moderate Alzheimer's disease. This asks for a reassessment of the muscarinic hypothesis for the treatment of this disease.

[Pharmacological activity of the new adamantane derivative--potential antiparkinson preparation during subchronic administration]

The effect of a new potential antiparkinsonian drug, N-(2-adamantyl)hexamethyleneimine hydrochloride (A-7), upon some behavioral parameters was studied in rats after subchronic 14-day treatment. Also studied was the effect of abrupt termination of a prolonged (22-day) drug administration. The subchronic treatment with A-7 at a dose of 10, 20, or 40 mg/kg did not produce significant changes in coordination, explorative behavior, muscle tone, and aggression level. At the same time, the 14-day treatment with A-7 at a dose of 10 mg/kg increased the pain threshold; A-7 at a dose of 40 mg/kg (but not 10 or 20 mg/kg) increased the spontaneous motor activity. Upon abrupt termination of the drug administration after a prolonged treatment sensitivity of the test animals with respect to the MFTP neurotoxin as compared to that observed in the non-drug control group.

Gastric antisecretory effects of compound BP 2-94: a histamine H3-receptor agonist prodrug

Compound BP 2-94 is an orally available prodrug of the histamine H3-receptor agonist (R)-alpha-methylhistamine, which was found to produce higher plasma levels than the parent drug in humans. In the present study radioimmunoassay was carried out in dogs to investigate the generation of (R)-alpha-methylhistamine in vivo after intragastric administration of the prodrug. The effects of BP 2-94 on gastric acid secretion and on histamine, gastrin, and somatostatin release were also investigated. After intragastric administration of BP 2-94 (10 mg/kg), both the prodrug and (R)-alpha-methylhistamine were detected in plasma: plasma levels of (R)-alpha-methylhistamine decayed with a T1/2 of about 1 hr and displayed concentrations as high as 50-fold the EC50 of the drug at the H3 receptor for at least 2 hr. In conscious dogs provided with gastric fistula BP 2-94, administered at 10 and 30 mg/kg intragastrically, caused a dose-dependent inhibition (maximum reduction was about 80%) of the acid secretion stimulated by 2-deoxy-D-glucose, whereas (R)-alpha-methylhistamine (20 mg/kg, intragastrically) was ineffective. BP 2-94 (30 mg/kg, intragastrically) significantly reduced the acid secretion stimulated by bombesin, while leaving unaffected that induced by histamine. The increase in plasma gastrin levels induced by 2-deoxy-D-glucose, bombesin or a test meal was not significantly modified by BP 2-94 (30 mg/kg, intragastrically). In anesthetized dogs BP 2-94 (30 mg/kg, intragastrically) significantly reduced histamine release detected in the portal vein under bombesin infusion, whereas it did not modify gastrin and somatostatin plasma levels. These data indicate that BP 2-94 is a good prodrug of (R)-alpha-methylhistamine in the dog, causing an efficacious reduction of acid secretion induced by both 2-deoxy-D-glucose and bombesin. Moreover, the study of paracrine and hormonal mediators of acid secretion confirms that the main mechanism underlying inhibition of acid production induced by H3-receptor activation is the impairment of histamine release from gastric histaminocytes (possibly enterochromaffin-like cells).

The profile of sabcomeline (SB-202026), a functionally selective M1 receptor partial agonist, in the marmoset

1. Sabcomeline (SB-202026, 0.03 mg kg(-1), p.o.), a potent and functionally selective M1 receptor partial agonist, caused a statistically significant improvement in the performance of a visual object discrimination task by marmosets. No such improvement was seen after RS86 (0.1 mg kg(-1), p.o.). 2. Initial learning, which only required an association of object with reward and an appropriate response to be made, was not significantly affected. Reversal learning, which required both the extinction of the previously learned response and the acquisition of a new response strategy, was significantly improved after administration of sabcomeline (0.03 mg kg(-1), p.o.). 3. Sabcomeline (0.03 and 0.1 mg kg(-1), p.o.) had no significant effect on mean blood pressure measured for 2 h after administration in the conscious marmoset. 4. Sabcomeline (0.03 mg kg(-1), p.o.) caused none of the overt effects such as emesis or behaviours often seen after the administration of muscarinic agonists, e.g. face rubbing and licking. 5. This is the first study to demonstrate cognitive enhancement by a functionally selective M1 receptor partial agonist in a normal (i.e. non-cognitively impaired) non-human primate and this effect was seen at a dose which did not cause side effects. 6. Perseverative behaviour and deficient acquisition of new information are seen in patients with Alzheimer's disease (AD). Therefore the data suggest that sabcomeline might be of therapeutic benefit in the treatment of AD.

2-Iminohomopiperidinium salts as selective inhibitors of inducible nitric oxide synthase (iNOS)

An attractive approach to the treatment of inflammatory conditions such as osteo- and rheumatoid arthritis, inflammatory bowel disease, and sepsis is through the selective inhibition of human inducible nitric oxide synthase (hiNOS) since localized excess nitric oxide (NO) release has been implicated in the pathology of these diseases. A series of monosubstituted iminohomopiperidinium salts possessing lipophilic functionality at ring positions 3, 5, 6, and 7 has been synthesized, and series members have demonstrated the ability to inhibit the hiNOS isoform with an IC50 as low as 160 nM (7). Compounds were found that selectively inhibit hiNOS over the human endothelial constitutive enzyme (heNOS) with a heNOS/hiNOS IC50 ratio in excess of 100 and as high as 314 (9). Potencies for inhibition of hiNOS and the human neuronal constitutive enzyme (hnNOS) are comparable. Substitution in the 3 and 7 positions provides compounds that exhibit the greatest degree of selectivity for hiNOS and hnNOS over heNOS. Submicromolar potencies for 6 and 7 in a mouse RAW cell assay demonstrated the ability of these compounds to inhibit iNOS in a cellular environment. These latter compounds were also found to be orally bioavailable and efficacious due to their ability to inhibit the increase in plasma nitrite/nitrate levels in a rat LPS model.

Inhibition of human colonic adenylate cyclase by RMI 12330 A

RMI 12330 A, a compound of the lactamamide series, is a potent inhibitor of vasoactive intestinal polypeptide(VIP)- and prostaglandin (PG)-stimulated colonic secretion in the rat. This substance was tested on the adenylate cyclase system in human colonic mucosa. RMI 12330 A inhibited PGE2-, 16,16-dimethyl-PGE2- as well as VIP-sensitive adenylate cyclases in a dose-related manner. Half-maximal inhibition of hormone-stimulated enzyme activities occurred at a lactamimide concentration of about 0.15 mM. Lactamimide inhibition was non-competitive. Our results are compatible with the concept of RMI 12330 A acting as an inhibitor of colonic secretion via inhibition of hormone-sensitive adenylate cyclase. Since basal, NaF- and guanylyl-imidodiphosphate-stimulated enzyme activities were also affected by this compound, we may conclude that RMI 12330 A is a non-specific inhibitor of the human colonic adenylate cyclase system.

Influence of administration route and dosage schedule on tumor response to nitrosoheptamethyleneimine in rats

Nitrosoheptamethyleneimine (NHMI) was tested for carcinogenicity in Fischer-344 and Sprague-Dawley rats by intragastric administration and subcutaneous injection. Cumulative doses ranged from 5.5 to 1,200 mg/kg, and dosage schedules ranged from 40 serial administrations to one single injection. No difference in response was seen between sexes or strains of rats. Following the highest carcinogen doses by intragasritc administration, a high incidence of squamous-cell tumors occurred in the lung. The highest incidence of squamous-cell tumors occurred in the nasal cavity, trachea and esophagus. Following subcutaneous injection, tumors induced in the lungs were all alveologenic adenocarcinomas. The upper respiratory and gastrointestinal tracts were again the most commonly affected sites, with tumors similar to those of the first group. Intragastric administration was more effective in producing tumors than was subcutaneous injection, and administration of multiple small doses was more efficient than single large doses. The results demonstrated that the route and schedule of administration markedly influenced the tumor response to NHMI, both quantitatively and qualitatively.

Effects of a new oral hypoglycemic agent on glucose and insulin after oral glucose loading. A controlled study

l-(2-pyrimidinyl)-4-imino-l, 4-dihydropyridine hydrochloride is a new compound which after oral administration of a single dose of 400 mg. causes significant reductions of hyperglycemia and insulin response in human subjects after an oral glucose load. These results were obtained when compared to a single dose of 200 mg. of phenformin hydrochloride or placebo in a double-blind completely randomized crossover study with placebo and phenformin. Both drugs also produced a significant fall in the fasting serum glucose value before the oral glucose load without any significant effect on serum insulin values. Both drugs produced similar adverse symptoms in the six healthy subjects who participated in the study.