Cyst-based ecotoxicological tests using Anostracans: comparison of two species of Streptocephalus

Cyst-based ecotoxicological tests are simple and low-cost methods for assessing acute toxicity. Nevertheless, only a few comparative studies on their sensitivity are known. In the present study, the suitability of the use of two freshwater Anostracan species, Streptocephalus rubricaudatus and S. texanus, was assessed. The impact of 16 priority pollutants (4 heavy metals, 11 organic, and 1 organometallic compounds) on these two species, as well as on Artemia salina (Artoxkit M), Daphnia magna (International Organization for Standardization 6341), and S. proboscideus (Streptoxkit F) was assessed. For indicative comparison, bioassays using Brachionus calyciflorus (Rotoxkit F) and Photobacterium phosphoreum (Microtox) were also performed. For heavy metals (K2Cr2O7, Cd2+, Zn2+, Cu2+), the sensitivity of the two studied Streptocephalus species was slightly higher than that of D. magna. It was significantly more elevated than for the marine A. salina. For organic and organometallic micropollutants [phenol, 3,5-dichlorophenol, pentachlorophenol (PCP), hydroquinone, linear alkylbenzene sulfonate, sodium dodecyl sulfate, tributylphosphate, dimethylphthalate, atrazine, lindane, malathion, tributyltin chloride (TBT-Cl)], the sensitivity of the 4 anostracan species was of the same order of magnitude as that of D. magna. Artemia salina was slightly less sensitive to some organic compounds (PCP, hydroquinone, TBT-Cl). The sensitivity of S. rubricaudatus to organic solvents was low. On the other hand, this anostracan was quite sensitive to NaCl. Thus, its use is restricted to freshwater samples. The evaluation of global practicability of these two tests confirms that cyst-based freshwater anostracans may be used to perform low-cost tests at a sensitivity comparable to that of D. magna (24 h immobilization test).

Signalling by the cleaner shrimp Periclimenes longicarpus

Signals increase the fitness of a sender by altering the behaviour of receivers. For cooperative interactions biological market theory proposes that signalling strength may be linked to supply and demand. In this context, a recent laboratory experiment demonstrated that cleaner shrimps may advertise their service to client reef fish and that the advertisement is linked to hunger levels. We investigated signalling by the cleaner shrimp Periclimenes longicarpus in the field to test more detailed predictions of biological market theory. Shrimps often clapped with their pair of claws in response to approaching clients. In line with both theory and the previous study, the probability of clapping increased when the shrimps had been food deprived and clapping shrimps were more likely to clean than nonclapping individuals. However, we found no evidence for the market theory prediction that signalling was targeted specifically to visiting client species with the option to choose other cleaning stations. Instead, shrimps signalled more frequently towards predatory clients than towards nonpredatory clients. We conclude that the signal does not serve primarily to attract the choosy clients but to convey information about identity as preconflict management to avoid predation.

Octopus Standard Automated Perimetry, Pulsar Perimetry, Moorfields Motion Displacement Test and Heidelberg Retinal Tomography in Glaucoma Detection - A Comparison of Diagnostic Accuracy

Purpose: To investigate the accuracy of 4 clinical instruments in the detection of glaucomatous damage. Methods: 102 eyes of 55 test subjects (Age mean = 66.5yrs, range = [39; 89]) underwent Heidelberg Retinal Tomography (HRTIII), (disc area<2.43); and standard automated perimetry (SAP) using Octopus (Dynamic); Pulsar (TOP); and Moorfields Motion Displacement Test (MDT) (ESTA strategy). Eyes were separated into three groups 1) Healthy (H): IOP<21mmHg and healthy discs (clinical examination), 39 subjects, 78 eyes; 2) Glaucoma suspect (GS): Suspicious discs (clinical examination), 12 subjects, 15 eyes; 3) Glaucoma (G): progressive structural or functional loss, 14 subjects, 20 eyes. Clinical diagnostic precision was examined using the cut-off associated with the p<5% normative limit of MD (Octopus/Pulsar), PTD (MDT) and MRA (HRT) analysis. The sensitivity, specificity and accuracy were calculated for each instrument. Results: See table Conclusions: Despite the advantage of defining glaucoma suspects using clinical optic disc examination, the HRT did not yield significantly higher accuracy than functional measures. HRT, MDT and Octopus SAP yielded higher accuracy than Pulsar perimetry, although results did not reach statistical significance. Further studies are required to investigate the structure-function correlations between these instruments.

Effects of selection and drift on G matrix evolution in a heterogeneous environment: a multivariate Qst-Fst Test with the freshwater snail Galba truncatula.

Unraveling the effect of selection vs. drift on the evolution of quantitative traits is commonly achieved by one of two methods. Either one contrasts population differentiation estimates for genetic markers and quantitative traits (the Q(st)-F(st) contrast) or multivariate methods are used to study the covariance between sets of traits. In particular, many studies have focused on the genetic variance-covariance matrix (the G matrix). However, both drift and selection can cause changes in G. To understand their joint effects, we recently combined the two methods into a single test (accompanying article by Martin et al.), which we apply here to a network of 16 natural populations of the freshwater snail Galba truncatula. Using this new neutrality test, extended to hierarchical population structures, we studied the multivariate equivalent of the Q(st)-F(st) contrast for several life-history traits of G. truncatula. We found strong evidence of selection acting on multivariate phenotypes. Selection was homogeneous among populations within each habitat and heterogeneous between habitats. We found that the G matrices were relatively stable within each habitat, with proportionality between the among-populations (D) and the within-populations (G) covariance matrices. The effect of habitat heterogeneity is to break this proportionality because of selection for habitat-dependent optima. Individual-based simulations mimicking our empirical system confirmed that these patterns are expected under the selective regime inferred. We show that homogenizing selection can mimic some effect of drift on the G matrix (G and D almost proportional), but that incorporating information from molecular markers (multivariate Q(st)-F(st)) allows disentangling the two effects.

How reliable is the monitoring of permanent vegetation plots? A test with multiple observers

Questions: A multiple plot design was developed for permanent vegetation plots. How reliable are the different methods used in this design and which changes can we measure? Location: Alpine meadows (2430 m a.s.l.) in the Swiss Alps. Methods: Four inventories were obtained from 40 m(2) plots: four subplots (0.4 m(2)) with a list of species, two 10m transects with the point method (50 points on each), one subplot (4 m2) with a list of species and visual cover estimates as a percentage and the complete plot (40 m(2)) with a list of species and visual estimates in classes. This design was tested by five to seven experienced botanists in three plots. Results: Whatever the sampling size, only 45-63% of the species were seen by all the observers. However, the majority of the overlooked species had cover < 0.1%. Pairs of observers overlooked 10-20% less species than single observers. The point method was the best method for cover estimate, but it took much longer than visual cover estimates, and 100 points allowed for the monitoring of only a very limited number of species. The visual estimate as a percentage was more precise than classes. Working in pairs did not improve the estimates, but one botanist repeating the survey is more reliable than a succession of different observers. Conclusion: Lists of species are insufficient for monitoring. It is necessary to add cover estimates to allow for subsequent interpretations in spite of the overlooked species. The choice of the method depends on the available resources: the point method is time consuming but gives precise data for a limited number of species, while visual estimates are quick but allow for recording only large changes in cover. Constant pairs of observers improve the reliability of the records.

The P450 oxidoreductase genotype is associated with CYP3A activity in vivo as measured by the midazolam phenotyping test.

CYP3A4, CYP3A5 and CYP3A7 are hepatic enzymes that metabolize about 50% of drugs on the market, with a large overlap in their specificities. We investigated the genetic bases that contribute to the variation of CYP3A activity. We phenotyped 251 individuals from two independent studies (182 patients treated with methadone and 69 patients with clozapine) for CYP3A activity using the midazolam phenotyping test and genotyped them for CYP3A4, CYP3A5, and CYP3A7 genetic variants, including the single nucleotide polymorphism (SNP) rs4646437C>T in intron 7 of CYP3A4. Owing to the fact that CYP enzymes require electron transfer through the P450 oxidoreductase (POR), and functional impairment has been shown for the POR*28 SNP, this polymorphism was also analysed. We show that CYP3A4, CYP3A5 and CYP3A7 genotypes, including the SNP rs4646437C>T, do not reflect the inter-individual variability of CYP3A activity (P>0.1). In contrast, POR*28 TT genotype presents a 1.6-fold increase in CYP3A activity compared with POR*28C carriers (n = 182, P = 0.004). This finding was replicated in the second independent dataset (n = 69, P = 0.04). The SNP POR*28 seems to be a better genetic marker of the variability of total CYP3A activity in vivo than CYP3A4, CYP3A5 and CYP3A7 genetic variants.

Endocrine response and perceived stress test during an experimental challenge task in adult survivors of a childhood cancer.

BACKGROUND: Although long-term implications of cancer in childhood or adolescence with regard to medical conditions are well documented, the impact on mental health and on response to stress, which may be an indicator of psychological vulnerability, is not yet well understood. In this study, psychological and physiological responses to stress were examined.¦PROCEDURE: Fifty-three participants aged 18-39 years (n = 25 survivors of childhood or adolescence cancer, n = 28 controls) underwent an experimental stress test, the Trier Social Stress Test (TSST). Participants were asked to provide repeated evaluations of perceived stress on visual-analogical scales and blood samples were collected before and after the TSST to measure plasma cortisol.¦RESULTS: The psychological perception of stress was not different between the two groups. However, the cancer survivors group showed a higher global plasma cortisol level as well as higher amplitude in the response to the TSST. The global cortisol level in cancer survivors was increased when depression symptoms were present. The subjective perception of stress and the plasma cortisol levels were only marginally correlated in both groups.¦CONCLUSIONS: It is suggested that the exposure to a life-threatening experience in childhood/adolescence increases the endocrine response to stress, and that the presence of depressive symptoms is associated with an elevation of plasma cortisol levels. A better knowledge of these mechanisms is important given that the dysregulations of the stress responses may cause psychological vulnerability. Pediatr Blood Cancer 2012; 59: 138-143. © 2011 Wiley Periodicals, Inc.

COLOX: a new blood-based test for colorectal cancer screening

INTRODUCTION/OBJECTIVES: Detection rates for adenoma and early colorectal cancer (CRC) are insufficient due to low compliance towards invasive screening procedures, like colonoscopy.Available non-invasive screening tests have unfortunately low sensitivity and specificity performances.Therefore, there is a large unmet need calling for a cost-effective, reliable and non-invasive test to screen for early neoplastic and pre-neoplastic lesions AIMS & Methods: The objective is to develop a screening test able to detect early CRCs and adenomas.This test is based on a nucleic acids multi-gene assay performed on peripheral blood mononuclear cells (PBMCs).A colonoscopy-controlled feasibility study was conducted on 179 subjects.The first 92 subjects was used as training set to generate a statistical significant signature.Colonoscopy revealed 21 subjects with CRC,30 with adenoma bigger than 1 cm and 41 with no neoplastic or inflammatory lesions.The second group of 48 subjects (controls, CRC and polyps) was used as a test set and will be kept blinded for the entire data analysis.To determine the organ and disease specificity 38 subjects were used:24 with inflammatory bowel disease (IBD),14 with other cancers than CRC (OC).Blood samples were taken from each patient the day of the colonoscopy and PBMCs were purified. Total RNA was extracted following standard procedures.Multiplex RT-qPCR was applied on 92 different candidate biomarkers.Different univariate and multivariate statistical methods were applied on these candidates and among them 60 biomarkers with significant p-values (<0.01) were selected.These biomarkers are involved in several different biological functions as cellular movement,cell signaling and interaction,tissue and cellular development,cancer and cell growth and proliferation.Two distinct biomarker signatures are used to separate patients without lesion from those with cancer or with adenoma, named COLOX CRC and COLOX POL respectively.COLOX performances were validated using random resampling method, bootstrap. RESULTS: COLOX CRC and POL tests successfully separate patients without lesions from those with CRC (Se 67%,Sp 93%,AUC 0.87) and from those with adenoma bigger than 1cm (Se 63%,Sp 83%,AUC 0.77),respectively. 6/24 patients in the IBD group and 1/14 patients in the OC group have a positive COLOX CRC CONCLUSION: The two COLOX tests demonstrated a high sensitivity and specificity to detect the presence of CRCs and adenomas bigger than 1 cm.A prospective, multicenter, pivotal study is underway in order to confirm these promising results in a larger cohort.

Pharmacokinetic drug interaction potential of risperidone with cytochrome p450 isozymes as assessed by the dextromethorphan, the caffeine, and the mephenytoin test.

Two published case reports showed that addition of risperidone (1 and 2 mg/d) to a clozapine treatment resulted in a strong increase of clozapine plasma levels. As clozapine is metabolized by cytochrome P450 isozymes, a study was initiated to assess the in vivo interaction potential of risperidone on various cytochrome P450 isozymes. Eight patients were phenotyped with dextromethorphan (CYP2D6), mephenytoin (CYP2C19), and caffeine (CYP1A2) before and after the introduction of risperidone. Before risperidone, all eight patients were phenotyped as being extensive metabolizers of CYP2D6 and CYP2C19. Risperidone at dosages between 2 and 6 mg/d does not appear to significantly inhibit CYP1A2 and CYP2C19 in vivo (median plasma paraxanthine/caffeine ratios before and after risperidone: 0.65, 0.69; p = 0.89; median urinary (S)/(R) mephenytoin ratios before and after risperidone:0.11, 0.12; p = 0.75). Although dextromethorphan metabolic ratio is significantly increased by risperidone (median urinary dextromethorphan/dextrorphan ratios before and after risperidone: 0.010, 0.018; p = 0.042), risperidone can be considered a weak in vivo CYP2D6 inhibitor, as this increase is modest and none of the eight patients was changed from an extensive to a poor metabolizer. The reported increase of clozapine concentrations by risperidone can therefore not be explained by an inhibition of CYP1A2, CYP2D6, CYP2C19 or by any combination of the three.

CYP3A activity measured by the midazolam test is not related to 3435 C >T polymorphism in the multiple drug resistance transporter gene.

A recent study with 69 Japanese liver transplants treated with tacrolimus found that the MDR13435 C >T polymorphism, but not the MDR12677 G >T polymorphism, was associated with differences in the intestinal expression level of CYP3A4 mRNA. In the present study, over 6 h, we measured the kinetics of a 75 microg oral dose of midazolam, a CYP3A substrate, in 21 healthy subjects genotyped for the MDR13435 C >T and 2677 G >T polymorphism. No statistically significant differences were found in the calculated pharmacokinetic parameters between the three 3435 C >T genotypes (TT, CT and CC group, respectively: Cmax (mean +/- SD: 0.30 +/- 0.08 ng/ml, 0.31 +/- 0.09 ng/ml and 0.31 +/- 0.11 ng/ml; Apparent clearance: 122 +/- 29 l/h, 156 +/- 92 l/h and 111 +/- 35 l/h; t1/2: 1.9 +/- 1.1 h, 1.6 +/- 0.90 h and 1.7 +/- 0.7 h). In addition, the 30-min 1'OH midazolam to midazolam ratio, a marker of CYP3A activity, determined in 74 HIV-positive patients before the introduction of antiretroviral treatment, was not significantly different between the three 3435 C >T genotypes (mean ratio +/- SD: 3.65 +/- 2.24, 4.22 +/- 3.49 and 4.24 +/- 2.03, in the TT, CT and CC groups, respectively). Similarly, no association was found between the MDR12677 G >T polymorphism and CYP3A activity in the healthy subjects or in the HIV-positive patients. The existence of a strong association between the activity of CYP3A and MDR13435 C >T and 2677 G >T polymorphisms appears unlikely, at least in Caucasian populations and/or in the absence of specific environmental factors.

Withholding antimalarials in febrile children who have a negative result for a rapid diagnostic test.

BACKGROUND: The availability of a rapid diagnostic test for malaria (RDTm) allows accurate diagnosis at all levels of health facilities. The objective of the present study was to evaluate the safety of withholding antimalarials in febrile children who have a negative test result. METHODS: We conducted a prospective 2-arm longitudinal study in areas of Tanzania that are moderately and highly endemic for malaria. Children with a history of fever were managed routinely by resident clinicians of 2 health facilities, except that no antimalarials were prescribed if the RDTm result was negative. Children were followed up at home on day 7. The main outcome was the occurrence of complications in children with negative RDTm results; children with positive RDTm results were followed up for the same outcomes for indirect comparison. RESULTS: One thousand children (median age, 24 months) were recruited. Six hundred three children (60%) had a negative RDTm result. Five hundred seventy-three (97%) of these children were cured on day 7. Forty-nine (8%) of the children with negative RDTm results spontaneously visited the dispensary before day 7, compared with 10 (3%) of the children with positive RDTm results. All children who had negative initial results had negative results again when they were tested either at spontaneous attendance or on day 7 because they were not cured clinically, except for 3 who gave positive results on days 2, 4, and 7 respectively but who did not experience any complication. Four children who had negative initial results were admitted to the hospital subsequently, all with negative results for malaria tests upon admission. Two of them died, of causes other than malaria. CONCLUSIONS: Not giving antimalarial drugs in febrile children who had a negative RDTm result was safe, even in an area highly endemic for malaria. Our study provides evidence for treatment recommendations based on parasitological diagnosis in children <5 years old.