Comment on "Global distribution of earthworm diversity"

Phillips et al (Reports, 25 October 2019, p. 480) incorrectly conclude that tropical earthworm communities are less diverse and abundant than temperate communities. This result is an artifact generated by some low-quality datasets, lower sampling intensity in the tropics, different patterns in richness-area relationships, the occurrence of invasive species in managed soils, and a focus on local rather than regional richness.

Plant preference for ammonium versus nitrate: a neglected determinant of ecosystem functioning?

Although nitrogen (N) availability is a major determinant of ecosystem properties, little is known about the ecological importance of plants' preference for ammonium versus nitrate (β) for ecosystem functioning and the structure of communities. We modeled this preference for two contrasting ecosystems and showed that β significantly affects ecosystem properties such as biomass, productivity, and N losses. A particular intermediate value of β maximizes the primary productivity and minimizes mineral N losses. In addition, contrasting β values between two plant types allow their coexistence, and the ability of one type to control nitrification modifies the patterns of coexistence with the other. We also show that species replacement dynamics do not lead to the minimization of the total mineral N pool nor the maximization of plant productivity, and consequently do not respect Tilman's R* rule. Our results strongly suggest in the two contrasted ecosystems that β has important consequences for ecosystem functioning and plant community structure.

The discovery of setileuton, a potent and selective 5-lipoxygenase inhibitor

The discovery of novel and selective inhibitors of human 5-lipoxygenase (5-LO) is described. These compounds are potent, orally bioavailable, and active at inhibiting leukotriene biosynthesis in vivo in a dog PK/PD model. A major focus of the optimization process was to reduce affinity for the human ether-a-go-go gene potassium channel while preserving inhibitory potency on 5-LO. These efforts led to the identification of inhibitor (S)-16 (MK-0633, setileuton), a compound selected for clinical development for the treatment of respiratory diseases.

Dependence of malignant proliferation associated with loss of PTEN on glucose concentration in the hyperglycemic range: Relevance to population studies linking hyperglycemia to unfavorable cancer prognosis

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Background: Loss of function of the tumor suppressor PTEN enhances malignant proliferation, but effects on cellular energy metabolism are less well characterized. Population studies show that the metabolic syndrome (characterized by hyperglycemia, hyperinsulinism, and obesity) is increasingly prevalent in affluent societies and is associated with adverse outcome of many cancers, but the molecular basis for this is poorly understood. Methods: We used a tetracycline-inducible PTEN expression vector in the PTEN-null U251 glioma cell line to characterize effects of PTEN on cellular energy metabolism. Results: Forced expression of PTEN led to decreased phospho-AKTSer473, decreased hexokinase II and HIF-1 alpha levels, and increased p53 levels. While proliferation of PTEN-positive cells was insensitive to variation in glucose concentration at levels higher than 2.5 mM, PTEN-null cells significantly increased proliferation with increasing glucose concentration across normal physiologic range to ∼10 mM. PTEN-null cells consumed more glucose than PTEN-positive cells (17.2 ± 2.0 vs. 8.8 ± 1.5 mM/million cells/48 hrs) and produced more lactate (35.9 ± 4.8 vs. 10.7 ± 2.3 mM/million cells/48 hrs). When cells were incubated in presence of 2-deoxy-glucose (2-DG), growth inhibition was greater for PTEN-null cells (47.4% inhibition relative to control without 2-DG) compared with PTEN-positive cells (10.8% inhibition relative to control without 2-DG). Conclusions: Loss of function of PTEN leads to increased glycolysis, and increased dependence on glucose availability. Only in the presence of glucose in the hyperglycemic range are maximal adverse effects of loss of PTEN on cellular proliferation and survival seen. This provides a novel mechanism to explain at least in part the relationship between hyperglycemia and cancer mortality observed in several large population studies. The data also suggest that PTEN status is relevant to selection of tumors likely to respond to experimental therapies that exploit glucose dependency.

No significant financial relationships to disclose.

Lack of clinical efficacy of a phosphodiesterase-4 inhibitor for treatment of heaves in horses

Phosphodiesterase-4 (PDE 4) enzyme inhibitors have been shown to have anti-inflammatory properties in various animal disease processes and therefore could be effective drugs for the treatment of equine airway diseases. The purpose of this study was to evaluate the efficacy and adverse effects of the PDE 4 inhibitor L-826,141 in horses with heaves. In a blinded parallel design, horses with heaves exposed daily to moldy hay were given a placebo for 14 days and then administered either L-826,141 (n = 6; loading dose of 1 mg/kg IV followed by 0.5 mg/kg IV q48h) or dexamethasone (n = 6; 0.04 mg/kg IV q24h) from days 15 to 29 (study 1). Pulmonary function and bronchoalveolar (BAL) cytology were evaluated weekly from baseline (day 0) to 29 days. In study 2, horses were treated with L-826,141 (1.0 mg/kg IV q24h) for 8 days. Although ex vivo lipopolysaccharide-induced tumor necrosis factor (TNF)-alpha and LTB4 production by fresh blood were inhibited up to 90% after repeated administrations of L-826,141, this treatment failed to improve lung function. In contrast, dexamethasone (positive control) treatment resulted in significant improvement in lung mechanics and airway function in all horses. Neither drug had a significant effect on BAL total cell counts and differential cytology. Administration of the PDE 4 inhibitor L-826,141 for up to 14 days to horses with heaves was not associated with an improvement in airway function or inflammation. These findings suggest that the PDE 4 enzyme is not a key mediator of lung inflammation in heaves.

2,3-Diarylthiophenes as selective EP1 receptor antagonists

The synthesis and the EP(1) receptor binding affinity of 2,3-diarylthiophene derivatives are described. The evaluation of the structure-activity relationship (SAR) in this series led to the identification of compounds 4, 7, and 12a, which exhibit high affinity for the human EP(1) receptor and a selectivity greater than 100-fold against the EP(2), EP(3), EP(4), DP, FP, and IP receptors and greater than 25-fold versus the TP receptor. These three antagonists present good pharmacokinetics in rats and significant differences in the way they are distributed in the brain.

Optimization of a tertiary alcohol series of phosphodiesterase-4 (PDE4) inhibitors: structure-activity relationship related to PDE4 inhibition and human ether-a-go-go related gene potassium channel binding affinity

A SAR study on the tertiary alcohol series of phosphodiesterase-4 (PDE4) inhibitors related to 1 is described. In addition to inhibitory potency against PDE4 and the lipopolysaccharide-induced production of TNFalpha in human whole blood, the binding affinity of these compounds for the human ether-a-go-go related gene (hERG) potassium channel (an in vitro measure for the potential to cause QTc prolongation) was assessed. Four key structural moieties in the molecule were studied, and the impact of the resulting modifications in modulating these activities was evaluated. From these studies, (+)-3d (L-869,298) was identified as an optimized structure with respect to PDE4 inhibitory potency, lack of binding affinity to the hERG potassium channel, and pharmacokinetic behavior. (+)-3d exhibited good in vivo efficacy in several models of pulmonary function with a wide therapeutic index with respect to emesis and prolongation of the QTc interval.

Substituted 2-pyridinemethanol derivatives as potent and selective phosphodiesterase-4 inhibitors

The synthesis and the phosphodiesterase-4 (PDE4) inhibitory activity of 2-pyridinemethanol derivatives is described. The evaluation of the structure-activity relationship (SAR) in this series of novel PDE4 inhibitors led to the identification of compound 9 which exhibits excellent in vitro activity, desirable pharmacokinetic parameters and good efficacy in animal models of bronchoconstriction.

Substituted aminopyridines as potent and selective phosphodiesterase-4 inhibitors

The synthesis and the biological evaluation of new potent phosphodiesterase type 4 (PDE4) inhibitors are presented. This new series was elaborated by replacement of the metabolically resistant phenyl hexafluorocarbinol of L-791,943 (1) by a substituted aminopyridine residue. The structure-activity relationship of N-substitution on 3 led to the identification of (-)-3n which exhibited a good PDE4 inhibitor activity (HWB-TNFalpha=0.12 microM) and an improved pharmacokinetic profile over L-791,943 (rat t(1/2)=2 h). (-)-3n was well tolerated in ferret with an emetic threshold of 30 mg/kg (po) and was found to be active in the ovalbumin-induced bronchoconstriction model in guinea pig (54%, 0.1 mg/kg, ip) as well as the ascaris-induced bronchoconstriction model in sheep (64%/97%, early/late, 0.5 mg/kg, iv).

Substituted 4-(2,2-diphenylethyl)pyridine-N-oxides as phosphodiesterase-4 inhibitors: SAR study directed toward the improvement of pharmacokinetic parameters

A detailed SAR study directed toward the optimization of pharmacokinetic parameters for analogues of L-791,943 is reported. The introduction of a soft metabolic site on this structure permitted the identification of L-826,141 as a potent phosphodiesterase type 4 (PDE4) inhibitor that is well absorbed and that presents a shorter half-life than L-791,943 in a variety of animal species. The efficacy of L-826,141 is also demonstrated in different in vivo models.

Improving metabolic stability of phosphodiesterase-4 inhibitors containing a substituted catechol: prevention of reactive intermediate formation and covalent binding

A detailed study directed towards metabolic stability optimization of the alkoxy substituents on the catechol moiety of CDP-840 is reported. Replacement of the methoxy and cyclopentyloxy substituents by cyclobutyloxy and/or difluromethoxy groups resulted in the discovery of potent and selective PDE4 inhibitors where the formation of reactive metabolites that could covalently bind to microsomal protein was significantly reduced or eliminated.

Discovery of L-791,943: a potent, selective, non emetic and orally active phosphodiesterase-4 inhibitor

Structure-activity relationship studies directed toward improving the potency and metabolic stability of CDP-840 (3) resulted in the discovery of L-791,943 (11n) as a potent (HWB TNF-alpha = 0.67 microM) and orally active phosphodiesterase type 4 (PDE4) inhibitor. This compound, which bears a stable bis-difluoromethoxy catechol and a pendant hexafluorocarbinol, exhibited a long half-life in rat and in squirrel monkey. It is well tolerated in ferret with an emetic threshold greater than 30 mg/kg (po) and was found to be active in the ovalbumin-induced bronchoconstriction model in guinea pig and in the ascaris-induced bronchoconstriction models in sheep and squirrel monkey.

Quinolines as potent 5-lipoxygenase inhibitors: synthesis and biological profile of L-746,530

Leukotriene biosynthesis inhibitors have potential as new therapeutic agents for asthma and inflammatory diseases. A series of novel substituted 2-cyanoquinolines have been synthesized and the structure activity relationships were evaluated with respect to their ability to inhibit the formation of leukotrienes via the 5-lipoxygenase enzyme. [1S,5R]-2-Cyano-4-(3-furyl)-7-¿3-fluoro-5-[3-(3 alpha-hydroxy-6,8-dioxabicyclo[3.2.1]-octanyl)]phenoxymethyl ¿quinoline (L-746,530) 3 represents a distinct class of inhibitors and possesses in vitro and in vivo potency comparable or superior to naphthalenic analog (L-739,010) 2.

[Psychometric properties of the French version of the Modified Mini-Mental State (3MS) in elderly patients evaluated in geriatric psychiatry]

OBJECTIVE

This research evaluates the psychometric properties of the French version of the Modified Mini-Mental State (3MS), an instrument for the screening of dementia, in a sample of patients seen in geriatric psychiatry.

METHODS

Subjects (N = 94, 63 to 93 years of age) were outpatients of a service in geriatric psychiatry. In addition to the 3MS, a battery of tests evaluating the cognitive functioning and depressive symptomatology was administered.

RESULTS

Test-retest reliability coefficient was 0.87 for a subsample of 35 subjects. An exploratory factor analysis revealed 4 factors accounting for 63.2% of the variance. Cut-off scores of 79 to 80 (with years of education > or = 8) and 71 to 72 (with years of education < or = 7) presented the best combination sensitivity/specificity, respectively 0.80 and 0.96.

CONCLUSIONS

This study documents the psychometric properties of the French version of the 3MS for use in patients seen in geriatric psychiatry, in suggesting cut-off scores which take into account the level of education. This study underlines the influence of sociodemographic variables on test performance.

A new class of leukotriene biosynthesis inhibitor: the development of MK-0591

The evolution of MK-0591 (3-[1-(4-chlorobenzyl)-3-(t-butylthio)-5-(quinolin-2-ylmethoxy+ ++)indol-2-yl]- 2,2-dimethylpropanoic acid), 12, a potent, orally active leukotriene biosynthesis inhibitor is described. MK-0591 is currently undergoing clinical evaluation as a potential agent for the treatment of asthma and inflammatory bowel disease. It acts through a novel mechanism by a specific interaction with a membrane protein, 5-lipoxygenase activating protein (FLAP), which has been shown to be essential for LT synthesis in inflammatory cells. A brief comparison of its biological activity with that of its progenitors MK-886 and L-674,636 is described.

Nitrification of swine waste

Complete oxidation of ammonia nitrogen (approximately 1000 mg/L) to nitrite was observed in stabilized swine waste after 49 days in incubation at 400 rpm and 29 degrees C, only if 10% (v/v) activated sludge from a wastewater treatment unit and 1.5% (w/v) CaCO3, were added. Stabilized swine waste contains less than 0.09 most probable number (MPN) per millilitre of nitrosobacteria and 2.3 MPN/mL of nitrobacteria. In activated sludge, the concentrations of these bacteria were 2.4 MPN/mL for nitrosobacteria and 4.2 x 10(5) MPN/mL for nitrobacteria. In the swine waste where ammonia was oxidized to nitrite, the nitrosobacteria growth increased to 5.5 x 10(5) MPN/mL, while the nitrobacteria growth decreased to 2.3 MPN/mL. Inoculation of a freshly stabilized swine waste with 10% (v/v) of the active nitrifying waste and addition of 1.5% (w/v) CaCO3, accelerated the oxidation of ammonia nitrogen to nitrite; the reaction was completed after only 5 days of incubation. Increasing the incubation period to 10 days resulted in the complete oxidation of the accumulated nitrite to nitrate. In the stabilized swine waste, complete nitrification without accumulation of nitrite was obtained in only 5 days of incubation when the waste was inoculated with both enriched nitrifying populations (10(6)-10(7) MPN/mL).

The effect of fatigue on the binding of glycolytic enzymes in the isolated gastrocnemius of Rana pipiens

Fatigue of isolated gastrocnemius muscles from R. pipiens leads to a marked increase in the proportion of phosphofructokinase bound to the particulate fraction and a decrease in the binding of lactate dehydrogenase, pyruvate kinase, creatine phosphokinase and glyceraldehyde-3-phosphate dehydrogenase. Only the proportion of aldolase bound to the particulate fraction was unaffected by fatigue. This pattern was unchanged when fatigued muscles were extracted at pH 6.5 rather than 7.5. Thus, muscle fatigue leads to opposite changes in the binding of the glycolytic enzymes.

Pharmacokinetics of mexiletine in the elderly

The effect of advancing age on the kinetics of the antiarrhythmic agent mexiletine was studied by comparing various kinetic parameters calculated after administration of a single oral dose of mexiletine hydrochloride to seven elderly and eight young healthy volunteers. The rate of absorption of the drug from the gastrointestinal tract was significantly slower in the elderly (1.37 +/- 0.51 hr-1) than in the young group (2.25 +/- 0.79 hr-1). The mean values for elimination half-life and oral clearance were 12.3 +/- 3.7 hr and 10.3 +/- 5.4 mL/min/kg respectively in the young group and 14.4 +/- 4.5 hr and 8.5 +/- 2.9 mL/min/kg respectively in the elderly group. Neither of these parameters was significantly different between the two groups. The amount of mexiletine eliminated in urine up to 48 hours postdose was identical in both groups and represented less than 5% of the administered dose. It is concluded that the age-related modifications in the kinetics of mexiletine are not clinically important during chronic administration of the drug.