New structure–activity relationship studies in a series of N,N-bis(cyclohexanol)amine aryl esters as potent reversers of P-glycoprotein-mediated multidrug resistance (MDR)

As a continuation of previous research on a new series of potent and efficacious P-gp-dependent multidrug resistant (MDR) reversers with a N,N-bis(cyclohexanol)amine scaffold, we have designed and synthesized several analogs by modulation of the two aromatic moieties linked through ester functions to the N,N-bis(cyclohexanol)amine, aiming to optimize activity and to extend structure–activity relationships (SAR) within the series. This scaffold, when esterified with two different aromatic carboxylic acids, gives origin to four geometric isomers (cis/trans, trans/trans, cis/cis and trans/cis).The new compounds were tested on doxorubicin-resistant erythroleukemia K562 cells (K562/DOX) in the pirarubicin uptake assay. Most of them resulted in being potent modulators of the extrusion pump P-gp, showing potency values ([I]_0.5) in the submicromolar and nanomolar range. Of these, compounds 2b, 2c, 3d, 5a–d and 6d, showed excellent efficacy with a α_max close to 1. Selected compounds (2d, 3a, 3b, 5a–d) were further studied to evaluate their doxorubicin cytotoxicity potentiation (RF) on doxorubicin-resistant erythroleukemia K562 cells and were found able to enhance significantly doxorubicin cytotoxicity on K562/DOX cells.The results of both pirarubicin uptake and the cytotoxicity assay, indicate that the new compounds of the series are potent P-gp-mediated MDR reversers. They present a structure with a mix of flexible and rigid moieties, a property that seems critical to allow the molecules to choose the most productive of the several binding modes possible in the transporter recognition site.In particular, compounds 5c and 5d, similar to the already reported analogous isomers 1c and 1d,²⁹ are potent and efficacious modulators of P-gp-dependent MDR and may be promising leads for the development of MDR-reversal drugs.     

Stevens-Johnson Syndrome Associated with Drugs and Vaccines in Children: A Case-Control Study

Objective

Stevens-Johnson Syndrome (SJS) is one of the most severe muco-cutaneous diseases and its occurrence is often attributed to drug use. The aim of the present study is to quantify the risk of SJS in association with drug and vaccine use in children.

Methods

A multicenter surveillance of children hospitalized through the emergency departments for acute conditions of interest is currently ongoing in Italy. Cases with a diagnosis of SJS were retrieved from all admissions. Parents were interviewed on child’s use of drugs and vaccines preceding the onset of symptoms that led to the hospitalization. We compared the use of drugs and vaccines in cases with the corresponding use in a control group of children hospitalized for acute neurological conditions.

Results

Twenty-nine children with a diagnosis of SJS and 1,362 with neurological disorders were hospitalized between 1^st November 1999 and 31^st October 2012. Cases were more frequently exposed to drugs (79% vs 58% in the control group; adjusted OR 2.4; 95% CI 1.0–6.1). Anticonvulsants presented the highest adjusted OR: 26.8 (95% CI 8.4–86.0). Significantly elevated risks were also estimated for antibiotics use (adjusted OR 3.3; 95% CI 1.5–7.2), corticosteroids (adjusted OR 4.2; 95% CI 1.8–9.9) and paracetamol (adjusted OR 3.2; 95% CI 1.5–6.9). No increased risk was estimated for vaccines (adjusted OR: 0.9; 95% CI 0.3–2.8).

Discussion

Our study provides additional evidence on the etiologic role of drugs and vaccines in the occurrence of SJS in children.     

Synthesis and enantioselectivity of the enantiomers of PG9 and SM21, new potent analgesic and cognition-enhancing drugs

The enantiomers of two α-tropanyl esters, SM₂₁ (1) and PG₉ (2), derived from (+)-R-hyoscyamine, that act by increasing the central cholinergic tone, were obtained by esterification after resolution of the corresponding racemic acids [(−)-S-1, (−)-R-2 and (+)-S-2] and by stereospecific synthesis [(+)-R-1]. Their analgesic and cognition-enhancing activities were tested in mice and their ACh-releasing properties determined on rat parietal cortex. These compounds show enantioselectivity in analgesic and cognition-enhancing tests on mice, the eutomers being the isomers which possess the same spatial arrangement of the groups on the chiral atom as (+)-R hyoscyamine [(+)-R-SM₂₁, (+)-S-PG₉]. The ACh-releasing effect of the enantiomers of SM₂₁ in rats is in agreement with the results in mice, while PG₉ enantiomers do not show any appreciable enantioselectivity in this test. On the basis of the different effects of the 5-HT₄ antagonist SDZ 205557 on analgesia induced by the enantiomers of 1 and 2 and by (+)-R-hyoscyamine and the α-tropanyl ester of 2-phenylpropionic acid 3, a mechanism of action is proposed for this class of compounds. © 1996 Wiley-Liss, Inc.     

Effect of enrichment on variation and results in the light/dark test

Several confounding factors may influence the outcome of an experiment and the extent of inter-individual variation. The aim of this study was to investigate if cage enrichment induces an effect on experimental mean values and on inter-individual variation in the light/dark paradigm using diazepam as the anxiolytic drug. The behaviour of 216 naive adult male mice of two different strains (BALB/c and C57BL/6) was studied. The animals were housed in groups of four in 'non-enriched', 'enriched' (nesting material) or 'super-enriched' (nest-box, nesting material, wooden gnawing stick and PVC tube) cages. After 5 weeks the animals were assigned to one of three treatments: control (no injection), sham (saline injection i.p.) or diazepam (1 mg/kg bw i.p.) and tested in the light/dark test for 5 min. Variation data were analysed using three different methods (mean absolute deviation, coefficient of variation and power analysis). The C57BL/6 mice scored higher than BALB/c mice in activity related measurements and showed a less 'emotional' behaviour profile in the pharmacological control situation of the light/dark test. In this study the anxiolytic effect of diazepam was clear in BALB/c mice but absent in C57BL/6 mice. Mice housed in enriched and super-enriched cages gained more weight than mice in non-enriched cages, although food intake was not affected. Generally, the strain of mouse had the greatest impact on both mean values and variation. However, there was no consistent increase for one particular strain. The choice of statistical method for analysing variation may influence the interpretation of within-group variability, but none of the methods showed any significant differences between standard and enriched conditions on variability in any of the parameters measured.     

Effects of environmental enrichment for mice: variation in experimental results

This study focused on the effects of different enriched environments for mice in a number of behavioral and physiological parameters in 2 routine laboratory testing procedures: potency testing for tetanus vaccine and stress-induced hyperthermia. The variability in the results was studied by calculating and analyzing mean absolute deviations. Mice from enriched conditions weighed more and consumed more food than mice from standard housing conditions. However, mice from enriched conditions lost more body weight after being housed individually. Other physiological parameters showed no differences. Mice from standard conditions were more active in an open field, suggesting a tendency to overrespond to various stimuli in a testing environment. Mice from enriched environments were more tranquil and easier to handle. The enrichment did not influence the variability in any of the parameters measured, although earlier results and results of other studies suggest that the effects on the variability in results are parameter dependent. When enrichment does not influence variability, there is no reason for not introducing cage enrichment and by doing so contributing to the animals' welfare.     

Relaxation dynamics in three polypyridyl iron(II)-based complexes probed by nanosecond and sub-picosecond transient absorption spectroscopy

The results of a sub-picosecond transient absorption spectroscopy study on a mononuclear and two dinuclear low-spin iron(II) complexes is reported. The dinuclear derivatives are homonuclear (i.e. Fe–Fe) and heterodinuclear (Fe–Zn) in nature. The ligands we used were 2-pyridylmethyl-ketazine and 2-pyridylmethyl-hydrazone. Irradiation was made on the metal-to-ligand CT band occurring around 500 nm. The observed pattern of the relaxation decays is consistent with the population of the metastable ⁵T₂ ligand field state within the first 100 fs after the photon absorption from the three different chromophores. The suggested implication of triplet intermediate states was not detected. The ground state recovery was observed to occur with a time constant of 350 ps for the mononuclear complex and 1600–1800 ps for the two dinuclear complexes.     

Chlorella vulgaris cultivation using ricotta cheese whey as substrate for biomass production

Journal of Applied Phycology - The batch production of Chlorella vulgaris and its potential to profit the remnant nutritional components from ricotta cheese whey (RCW) were evaluated. From a first...     

Wind conditions experienced during the day predict nocturnal restlessness in a migratory songbird

A variety of methods have been used to study the relationship between wind conditions and departure decisions of migrant birds at stopover sites. These methods are either costly or suffer from inaccuracy in determining whether or not an individual has resumed migration. Here we present a novel and simple approach to studying the relationship between wind conditions and departure likelihood. Northern Wheatears Oenanthe oenanthe caught during stopover were temporarily caged to measure their nocturnal migratory restlessness, which is an accurate proxy for their individual departure likelihood. We then related the degree of nocturnal restlessness to wind conditions prevailing at the time of capture. Confirming the general pattern from previous studies of departure, the intensity of nocturnal migratory restlessness, and hence departure likelihood, increased with increasing wind support towards the migratory goal. This suggests that approximating the propensity to depart by measuring nocturnal migratory restlessness is a reliable way to study the effect that wind conditions experienced during stopover has on the departure decision of migrants. Our study also shows that nocturnal migrants possess the ability to use information gathered during the day for their departure decisions at night. Because measuring migratory restlessness is straightforward and inexpensive, our approach is ideally suited to test hypotheses regarding spatio‐temporal variation in wind selectivity in migrating birds.     

Testosterone, plumage colouration and extra-pair paternity in male North-American barn swallows

In most monogamous bird species, circulating testosterone concentration in males is elevated around the social female's fertile period. Variation in elevated testosterone concentrations among males may have a considerable impact on fitness. For example, testosterone implants enhance behaviours important for social and extra-pair mate choice. However, little is known about the relationship between natural male testosterone concentration and sexual selection. To investigate this relationship we measured testosterone concentration and sexual signals (ventral plumage colour and tail length), and determined within and extra-pair fertilization success in male North American barn swallows (Hirundo rustica erythrogaster). Dark rusty coloured males had higher testosterone concentrations than drab males. Extra-pair paternity was common (42% and 31% of young in 2009 and 2010, respectively), but neither within- nor extra-pair fertilization success was related to male testosterone concentration. Dark rusty males were less often cuckolded, but did not have higher extra-pair or total fertilization success than drab males. Tail length did not affect within- or extra-pair fertilization success. Our findings suggest that, in North American barn swallows, male testosterone concentration does not play a significant direct role in female mate choice and sexual selection. Possibly plumage colour co-varies with a male behavioural trait, such as aggressiveness, that reduces the chance of cuckoldry. This could also explain why dark males have higher testosterone concentrations than drab males.     

Diphenylcyclohexylamine derivatives as new potent multidrug resistance (MDR) modulators

A series of compounds with a diphenylmethyl cyclohexyl skeleton, loosely related to verapamil, has been synthesized and tested as MDR modulators on anthracycline-resistant erythroleukemia K 562 cells. Their residual cardiovascular action (negative inotropic and chronotropic activity as well as vasorelaxant activity) was evaluated on guinea-pig isolated atria preparations and on guinea-pig aortic strip preparations. Most compounds of the series possess a good MDR-reverting activity together with a low cardiovascular action. Among them, compounds 3a1, 7a, and 8a are more potent than verapamil as MDR reverters and lack any cardiovascular action; they can represent useful leads for the development of new safe MDR reversing drugs.