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PubMed1984

Aggregation and thromboxane synthesis and release in isolated sheep neutrophils and lymphocytes in response to complement stimulation.

In an attempt to determine possible cellular sources of thromboxane synthesis and release during intravascular complement activation, we prepared pure, viable fractions of neutrophils and lymphocytes from sheep blood. Lymphocytes were also isolated from thoracic duct lymph. Blood neutrophils and lymphocytes release thromboxane and the cells aggregate when challenged with zymosan-activated plasma. Blood lymphocytes release thromboxane in greater quantity than do neutrophils with the complement stimulus. Lymph lymphocytes, when stimulated with zymosan-activated plasma, did not release thromboxane or aggregate. These data suggest that both blood neutrophils and lymphocytes are likely sources of complement-initiated thromboxane synthesis and release in sheep.

Animals↗

PubMed1996

Changing priorities for improvement: the impact of low response rates in patient satisfaction.

BACKGROUND: A disturbing trend in patient satisfaction research has been a willingness to accept low response rates as inevitable. However, it may not be appropriate to generalize data based on low responses to the full population of patients, since to do so may threaten the validity of the findings. METHOD: Satisfaction data were collected from 19,556 inpatients discharged in 1994 from 76 hospitals using the 69-item NCG Patient Viewpoint Survey, an instrument that primarily uses a set of five response options, which are transformed to a 0- to 100-point scale. Surveys were sent to random samples of 100 to 1,400 patients, and were followed by postcard reminders. For each hospital sample, results for the "First 30%" were compared with those for "All Respondents," or the total number of respondents, for which the average response rate was 58%. FINDINGS: Results on individual scale scores and the subsequent improvement priorities for individual hospitals had a 50-50 chance of being different when the First 30% responses were compared with the All Respondents responses. For 9 out of 13 survey scales, the scores were significantly different between the First 30% and All Respondents when data were aggregated across all hospitals. For 42% of the 76 hospitals, a different set of scales would be identified as those most in need of improvement. DISCUSSION: The capriciousness of within-hospital differences based on the First 30% versus All Respondents brings into question the utility of patient satisfaction data based on low response rates even with a reliable instrument and with controlled, consistent data collection methods across hospitals. Target response rates should be set at 50% or higher. Additional research on the effects of response rates on patient satisfaction data are recommended.

Female↗

PubMed2001

Antiplatelet and anticoagulant effects of "HN-11 500," a selective thromboxane receptor antagonist.

The antiplatelet and anticoagulant effect of a thromboxane receptor (TX receptor) antagonist developed by Nycomed (Linz) has been studied in a placebo-controlled double-blind phase I study. Sixteen healthy male volunteers received different single oral doses of "HN-11 500" (C(14)H(15)NO(5)S(2); 1, 10, 100, 200, and 400 mg). Eight volunteers received placebo. The washout period between each dosage applied was at least 12 days. Platelet aggregation induced by the thromboxane mimetic "U 46 619" (C(21)H(34)0(4)) and platelet adhesion to siliconized glass were significantly and dose-dependently inhibited. The effect lasted between 3 and 4 h (10 mg) and 8 h (400 mg), respectively, and correlated well with the pharmacokinetic data. Platelet aggregation seems to be more sensitive to monitor the effects of HN-11 500 on platelet function than platelet adhesion. Plasma levels of 300 ng/ml HN-11 500 probably leads to >90% inhibition of platelet aggregation. The template bleeding time slightly increased but did not exceed the normal range. Furthermore, there was a wide variation of results. There were no significant changes in platelet counts, platelet-induced thrombin generation time (PITT), and blood coagulation parameters. All doses of HN-11 500 were well tolerated. HN-11 500 is a potent TX receptor antagonist (TXRA), which inhibits either platelet aggregation or platelet adhesion, which has not yet been described. In clinical routine, TXRAs have to demonstrate the effectiveness in large clinical trials for different clinical indications and to compete with single or combined administrations of cyclooxygenase (COX) inhibitors, thienovridines, thromboxane synthase inhibitors, and GIIb/IIIa inhibitors.

Adult↗

PubMedDate not supplied

The public health dashboard: a surveillance model for bioterrorism preparedness.

The City of Milwaukee Health Department piloted a short-term, near real-time syndromic surveillance and communication tool by using an existing secure regional Internet infrastructure. Voluntary, active syndromic case reporting by hospital Emergency Departments was combined with other data streams, including clinical laboratory reports of communicable disease, hospital emergency room diversions, ambulance runs, medical examiner reports of unusual or suspicious deaths, poison control and nursing hotline call volumes, and pharmacy over-the-counter sales. These data were aggregated into a "Surveillance Dashboard" format that was used to communicate community syndromic health trends to hospitals, Emergency Departments, and other providers using a secure Internet technology. Emergency Departments at 8 area hospitals reported a total of 314 cases meeting syndromic criteria from 26,888 patient encounters. Participants were satisfied with data entry and communications. All participating Emergency Departments received e-mail and text pager alerts sent by the Milwaukee Health Department. No unexplained findings or suggestions of an early outbreak were reported through syndrome surveillance for the 4-week duration of the project. Similar surveillance and communications systems could provide multiple benefits to Emergency Department workflow and management, as well as to public health and emergency response.

Bioterrorism↗

PubMed2003

Using hospital antibiogram data to assess regional pneumococcal resistance to antibiotics.

Antimicrobial resistance to penicillin and macrolides in Streptococcus pneumoniae has increased in the United States over the past decade. Considerable geographic variation in susceptibility necessitates regional resistance tracking. Traditional active surveillance is labor intensive and costly. We collected antibiogram reports from North Carolina hospitals and assessed pneumococcal susceptibility to multiple agents from 1996 through 2000. Susceptibility in North Carolina was consistently lower than the national average. Aggregating antibiogram data is a feasible and timely method of monitoring regional susceptibility patterns and may also prove beneficial in measuring the effects of interventions to decrease antimicrobial resistance.

Anti-Bacterial Agents↗

PubMed1995

Chronic lead treatment accelerates photochemically induced platelet aggregation in cerebral microvessels of mice, in vivo.

Effects of two chronic treatment levels with lead on platelet aggregation in cerebral (pial) microcirculation of the mouse were investigated. Exposure to lead was made by subcutaneous injections for 7 days of lead acetate dissolved in 5% glucose solution, vehicle. Two doses of lead were used, a low dose of 0.1 mg/kg and a high dose of 1.0 mg/kg. Adult male mice were divided into three groups, 10 each; one group was injected with vehicle (control), another was injected with the low dose, and the third was injected with the high dose. Additional mice were used for the determination of hematological parameters and for the lead level in serum of the three groups. On the eighth day, platelet aggregation in pial microvessels of these groups of mice was carried out in vivo. Animals were anesthetized (urethane, 1-2 mg/g, ip), the trachea was intubated, and a craniotomy was performed. Platelet aggregation in pial microvessels was induced photochemically, by activation of circulating sodium fluorescein (0.1 mg/25 g, iv) with an intense mercury light. The time required for the first platelet aggregate to appear in pial arterioles was significantly shorter in the lead-treated mice than in control. This effect was in a dose-dependent manner; 113 +/- 44 sec for low dose and 71 +/- 18 sec for high dose vs 155 +/- 25 sec for control, P < 0.02 and P < 0.001, respectively. Between the two lead-treated groups, the high dose significantly (P < 0.05) shortened the time to first aggregate. These data evidenced an increased susceptibility to cerebrovascular thrombosis as a result of exposure to lead.

Animals↗

PubMed1996

Autoantibodies to kininogen-phosphatidylethanolamine complexes augment thrombin-induced platelet aggregation.

Autoantibodies to the zwitterionic phospholipid (PL), phosphatidylethanolamine (PE), have been described in patients with thrombotic disease. We have reported that certain anti-PE antibodies (aPE) are not specific for PE, but are directed to PE-binding plasma proteins, high molecular weight kininogen (HK) and low molecular weight kininogen (LK). Kininogens bind to platelets and inhibit thrombin-induced platelet aggregation. This inhibition is specific for thrombin because kininogens do not inhibit platelet aggregation induced by adenosine diphosphate (ADP), collagen or calcium ionophore. To date, a platelet kininogen receptor has not been described. We recently reported that purified kininogens bind to purified PE in vitro. This opens the possibility that kininogens can bind to platelets by virtue of exposed PE in the platelet membrane. We thus questioned if aPE can recognize platelet bound kininogens and negate their antithrombotic property. Our experiments support this possibility by demonstrating that exogenously added kininogen-dependent IgG aPE markedly increased thrombin-induced platelet aggregation in vitro but did not alter ADP-induced aggregation. In contrast, kininogen independent IgG aPE which recognized PE per se did not augment thrombin-induced platelet aggregation. These data support a hypothesis that kininogen dependent aPE may cause thrombosis in vivo due to disruption of the normal antithrombotic effects of kininogen.

Animals↗

PubMed1998

A comparison of demographic characteristics of selected year 2000 health objectives for the United States, using behavioral risk factor surveillance system data for Alaska.

PURPOSE: The Behavioral Risk Factor Surveillance System (BRFSS) is a nationally developed and state-administered telephone survey which monitors the health behaviors and practices of adults aged 18 and older. One use of the survey is to monitor progress towards some of the Year 2000 Health Objectives for the United States. METHOD: Alaska has been conducting BRFSS monthly since January 1991, collecting approximately 128 interviews each month, for a yearly yield of approximately 1,530. Survey design allows for the aggregation of data over several years to accumulate sufficient sample size to look at health behaviors in subgroups of interest. We look at progress towards Year 2000 objectives for Alaska by various demographic characteristics: age, gender, education, employment, and geographic region. RESULTS: Survey data such as BRFSS can be used to monitor health behaviors and practices in a population in a cost-efficient and systematic manner.

Adolescent↗

PubMed2003

Individual psychotherapy in the outpatient treatment of adults with anorexia nervosa.

BACKGROUND: Anorexia nervosa is a disorder of high morbidity and significant mortality. It is commonest in young adult women, in whom the incidence may be increasing. The focus of treatment has moved to an outpatient setting and a number of differing psychotherapies are presently used in treatment. OBJECTIVES: The aim of the present review was to evaluate the evidence from randomised controlled trials for the efficacy of outpatient psychotherapies used in the treatment of older adolescents and adults with anorexia nervosa SEARCH STRATEGY: The strategy comprised database searches of MEDLINE, EXTRAMED, EMBASE,PSYCLIT, CURRENT CONTENTS, Cochrane Collaboration Controlled Trials Register and the Depression and Anxiety Neuroses Cochrane Group (CCDAN), a hand-search of The International Journal of Eating Disorders, and he reference lists of all papers selected. Personal letters were sent to identified notable researchers published in the area, requesting information on trials that are unpublished or in progress. SELECTION CRITERIA: All randomised controlled trials of adult individual outpatient therapy for anorexia nervosa as defined by the DSM-IV or similar international criterion. Quality ratings were made according to the CCDAN criteria and in addition, whether the trial had examined treatment integrity. DATA COLLECTION AND ANALYSIS: A range of outcome variables were selected, including physical state, severity of eating disorder attitudes and beliefs, interpersonal function, and general psychiatric symptom severity. Continuous outcome data comparisons were made with the standardized mean difference statistic, and binary outcome comparisons made with the relative risk statistic. Reliability of data extraction and quality ratings were made with the kappa statistic. Sensitivity analyses to evaluate the effects of trial quality and subgroup analyses to explore specific questions of treatment effects from different settings, frequency and duration of therapies were planned. MAIN RESULTS: Six small trials only, two of which included children or adolescents, were identified from the search and aggregation of data was not possible. Bias was possible due particularly to lack of blinding of outcome assessments. The results in two trials suggested that 'treatment as usual' or similar may be less efficacious than a specific psychotherapy. No specific treatment was consistently superior to any other specific approach. Dietary advice as a control arm had a 100% non-completion rate in one trial. REVIEWER'S CONCLUSIONS: No specific approach can be recommended from this review. It is unclear why 'treatment as usual' performed so poorly or why dietary advice alone appeared so unacceptable as the reasons for non-completion were not reported. There is an urgent need for large well-designed trials in his area.

Adolescent↗

PubMed2003

Combined hormonal versus nonhormonal versus progestin-only contraception in lactation.

BACKGROUND: Contraception for women who are breastfeeding is a public health issue of global importance. Each year over 100 million women make decisions about beginning or resuming contraception after childbirth. These decisions include both the choice of contraceptive method and the time at which its use begins, both of which continue to be debated by experts. Choices of contraception may be limited for lactating women due to concerns about hormonal effects on quality and quantity of milk, passage of hormones to the infant, and infant growth. Ideally, the contraceptive method chosen should not interfere with lactation. Additionally, because the return of menstruation and ovulation can be unpredictable in breastfeeding women, the timing of contraception initiation is important. OBJECTIVES: To determine the effect of combined oral contraceptives and progestin-only contraceptives on lactation. The a priori hypothesis is that combined oral contraception impairs lactation, making it less appropriate than progestin-only or nonhormonal contraception for breastfeeding women. SEARCH STRATEGY: We used PUBMED, POPLINE, EMBASE, LILACS, and Cochrane Controlled Trials Register computer searches, supplemented by review articles and contact with investigators. SELECTION CRITERIA: We sought all randomized controlled trials, reported in any language, that included any form of hormonal contraception compared with another form of hormonal contraception, nonhormonal contraception, or placebo during lactation. Hormonal contraception could include combined oral or injectable contraceptives, progestin-only oral or injectable contraceptives, hormonal implants, or hormonal intrauterine devices. Study participants included breastfeeding women of any age or parity who desired contraception. DATA COLLECTION AND ANALYSIS: We evaluated the methodological quality of each report and sought to identify duplicate reporting of data from multicenter trials. We abstracted data onto data collection forms. Principal outcome measures included quantity of milk; biochemical analysis of milk composition; initiation, maintenance and duration of lactation; infant growth; efficacy of contraceptive method while breastfeeding; and timing of contraception initiation and its effects on lactation. Because the trials did not have uniform interventions, often lacked quantifiable outcomes, and had poor methodological quality, we could not aggregate the data in a meta-analyses. MAIN RESULTS: Seven reports from five randomized controlled trials met our inclusion criteria. Most of the five trials did not specify their method used to generate a random sequence, method of allocation concealment, blinding of treatments, or use of an intention-to-treat analysis. Additionally, high loss to follow-up rates invalidated at least two studies. The findings from two reports comparing oral contraceptives to placebo during lactation were conflicting. Another trial found no inhibitory effects on lactation from progestin-only contraceptives. Finally, the WHO trial found no effect of progestin-only contraceptives on lactation but a decline in breast milk volume from combination contraceptives during lactation. High loss to follow-up rates, however, undermine the credibility of the WHO trial. No significant differences in infant growth or weight appeared in any of the included trials as a result of the use of hormonal contraception during lactation. REVIEWER'S CONCLUSIONS: Evidence from randomized controlled trials on the effect of hormonal contraceptives during lactation is limited and of poor quality; results should be interpreted with caution. The existing randomized controlled trials are insufficient to establish an effect of hormonal contraception, if any, on milk quality and quantity. Evidence is inadequate to make recommendations regarding hormonal contraceptive use for lactating women. At least one properly conducted randomized controlled trial of adequate size is urgently needed to address this question.

Contraceptives, Oral, Combined↗

PubMed2004

Value of updating a systematic review in surgery using individual patient data.

BACKGROUND: Previous research has highlighted the advantages of individual patient data (IPD) meta-analyses. However, they are resource intensive and take considerable time to complete. The aim of this study was to determine whether the extra investment is justified by greater accuracy or usefulness by means of a case study in surgery. METHODS: An updated review using IPD, where possible, was compared with an earlier version based on aggregate published data to determine whether there were statistically significant changes in estimates of effectiveness for hernia recurrence and persisting pain. Differences related to the type of laparoscopic repair, the type of open repair and methodological quality were also explored. RESULTS: The results for hernia recurrence changed little. However, the IPD update led to divergent conclusions for persisting pain. The published data implied a statistically significant benefit in favour of open repair, whereas the IPD result implied a statistically significant benefit in favour of laparoscopic repair (P < 0.001). Methodological quality did not account for this difference. CONCLUSION: Updating of systematic reviews using IPD can be conducted successfully in surgery. This example led to little change in estimates of effectiveness for hernia recurrence but yielded qualitatively different estimates for persisting pain, an outcome rarely included in the published reports.

Humans↗

PubMed2004

Associations between Bacillus subtilis sigmaB regulators in cell extracts.

The general stress regulon of Bacillus subtilis is induced by the activation of the sigma(B) transcription factor. Activation of sigma(B) occurs as a consequence of the dephosphorylation of its positive regulator RsbV by one of two phosphatases that respond to either physical or nutritional stress. The physical stress phosphatase (RsbU) requires a second protein (RsbT) for activity. Stress is thought to initiate a process that triggers the release of RsbT from a large inhibitory complex composed of multiple copies of two protein species, RsbR (and/or its paralogues) and RsbS. The stress-derived signal driving RsbT release is unknown, but it fails to develop in B. subtilis lacking either ribosome protein L11 or the ribosome-associated protein Obg. RsbR, RsbS, RsbT, Obg and ribosomes elute in common high-molecular-mass fractions during gel-filtration chromatography of crude B. subtilis extracts. This paper reports the investigation of the basis of this coelution by the examining of associations between these proteins in extracts prepared from wild-type and mutant B. subtilis, and Escherichia coli engineered to express RsbR, RsbS and RsbT. Large RsbR/RsbS complexes, distinct from ribosomes, were detected in extracts of both B. subtilis and E. coli. In E. coli, high-molecular-mass forms of RsbS were less abundant when RsbR was absent, but in B. subtilis, only when both RsbR and its principal paralogues were missing from the extract was this form less abundant. This finding is consistent with the notion that the RsbR paralogues, present in B. subtilis but not E. coli, can substitute for RsbR in such complexes. RsbT was not bound to RsbR/RsbS in any extract that was examined, including one prepared from a B. subtilis strain with an RsbS variant (RsbS59SA) that is believed to continuously associate with RsbT. The high-molecular-mass forms of RsbT were found to be Triton-sensitive and independent of any other B. subtilis protein for their formation. These probably represent RsbT aggregates. The data suggest that the contribution of ribosomes/Obg to sigma(B) activation does not involve formation of a stable association between these proteins and the Rsb complex. In addition, the binding of RsbT to RsbS/RsbR appears to be more labile than the binding between the previously analysed Rsb proteins which form inhibitory complexes. This, and the apparent proclivity of RsbT to aggregate, suggests an inherent instability in RsbT which may play a role in its regulation.

Bacillus subtilis↗

PubMed1998

Post-marketing studies: the work of the Drug Safety Research Unit.

The Drug Safety Research Unit (DSRU) is the centre for prescription-event monitoring (PEM) in England. PEM studies are noninterventional observational cohort studies which monitor the safety of newly marketed drugs. The need for post-marketing surveillance is well recognised in the UK and general practice is an ideal source of data. PEM studies are general practitioner (community)-based and exposure is based on dispensed prescription data in England. To date, 65 PEM studies have been completed with a mean cohort size of 10 979 patients and the DSRU database has clinical information on over 700000 patients prescribed new drugs. Unlike spontaneous reporting schemes, PEM produces incidence rates for events reported during treatment. Comparative studies can be conducted for drugs in the same class. The DSRU aggregates outcome data for pregnancies exposed to new drugs. Data for children and the elderly can also be specifically examined. PEM data have a number of advantages over data from computerised general practice databases in the UK. PEM is the only technique within the UK capable of monitoring newly marketed drugs in such a comprehensive and systematic way.

Antipsychotic Agents↗

PubMed1993

[Human neutrophilic defensin modulates the functional activity of the monocytes].

The effects of defensin, a peptide derived from human neutrophils, on aggregation of human peripheral blood monocytes were studied. Defensin (0.01 microgram/mL--100 micrograms/mL) caused a distinct dose dependent aggregation of normal donor monocytes. In addition, defensin increased the rate of monocyte aggregation induced by arachidonic acid or phorbol myristate acetate. Additional doses of defensin added to monocytes preactivated by this peptide produced no further aggregation. These data suggest that human defensin is an important physiological mediator released by neutrophils to regulate functions of monocytes.

Arachidonic Acid↗

PubMed1999

Crystallization and preliminary diffraction data of a platelet-aggregation inhibitor from the venom of Agkistrodon piscivorus piscivorus (North American water moccasin).

Applaggin (Agkistrodon piscivorus piscivorus platelet-aggregation inhibitor) is a potent inhibitor of blood platelet aggregation derived from the venom of the North American water moccasin. The protein consists of 71 amino acids, is rich in cysteines, contains the sequence-recognition site of adhesion proteins at positions 50-52 (Arg-Gly-Asp) and shares high sequence homology with other snake-venom disintegrins such as echistatin, kistrin and trigramin. Single crystals of applaggin have been grown and X-ray diffraction data have been collected to a resolution of 3.2 A. The crystals belong to space group P4(1)2(1)2 (or its enantiomorph), with unit-cell dimensions a = b = 63.35, c = 74.18 A and two molecules per asymmetric unit. Molecular replacement using models constructed from the NMR structures of echistatin and kistrin has not been successful in producing a trial structure for applaggin.

Amino Acid Sequence↗

PubMed1996

Three-dimensional metabolic and hemodynamic imaging of the normal and ischemic rat brain.

Unique insights into the topography of local metabolism/blood flow interrelationships in focal cerebral ischemia have afforded by the recent development of powerful image-processing techniques permitting three-dimensional (3D) autoradiographic image-averaging and analysis of replicate studies by a novel method termed "disparity analysis". This method, based upon a linear affine transformation model, directly estimates scaling, translation and rotation parameters simultaneously. The method was validated in awake Wister rats studied for local cerebral glucose metabolism (lCMRgl) with 14C-2-deoxyglucose. Brains were subserially sectioned, aligned by disparity analysis, and mapped into a common template so as to generate aggregate 3D data sets of the mean and standard deviation of the entire series (n = 9). Internal anatomic architecture was faithfully represented in the average image, and Fourier analysis revealed satisfactory retention of low-frequency information. The method was then applied to study metabolism/blood flow relationships in the acute focal ischemic penumbra of Sprague-Dawley rats subjected to distal photothrombotic middle cerebral artery (MCA) occlusion, coupled with permanent ipsilateral and 1 h contralateral common carotid artery occlusions. Matched series were studied for lCBF at 1.5 h and for lCMRgl at 1.25-2 h post-occlusion. The averaged lCBF image revealed the ischemic penumbra (defined as lCBF 20-40% of control) to form a "shell" around the cortical ischemic core and a confluent aggregate at the anterior and posterior poles of the core-zone. lCMRgl in the penumbra was heterogeneous, ranging from near-normal to markedly increased. An average lCMRgl/lCBF ratio data set revealed marked metabolism-flow uncoupling in penumbral pixels, averaging nearly five-fold above control ratio values. Sustained deflections of the DC potential were recorded in the penumbra, the site of marked uncoupling. This analysis defined for the first time the 3D topography of the ischemic penumbra and substantiated marked metabolism/flow dissociation, which is believed to be a metabolic consequence of the energy demand imposed by repeated peri-infarct depolarizations.

Animals↗

PubMed2005

Cluster aggregation and fragmentation kinetics model for gelation.

Gelation can occur in polymer, hydrogel, and colloid systems that undergo reversible aggregation-fragmentation (crosslinking accompanied by breakage). Gelation, characterized by rapid divergence of weight-average molecular weight and viscosity due to initial network formation, can be reversed if conditions change. In this paper, reversible aggregation and fragmentation in the pre-gelation time period are modeled with distribution kinetics. Moment equations are obtained from the population balance equation, and solved for eight different rate kernels. We identify the cases for which gelation is possible and obtain the critical values for the rate constants that allow gelation. The model provides a good simulation of published experimental data for aggregation and degradation of plasticized wheat gluten during thermo-mechanical treatments. We also evaluate two closure approximations based on Gamma and log-normal distributions, and conclude that log-normal closure predicts all five possible steady states, in agreement with the Vigil-Ziff criterion, and Gamma closure predicts only three. However, Gamma closure approximates the steady state either closely or exactly, whereas log-normal closure only poorly approximates the steady-state distribution.

Journal Article↗

PubMed2001

Variability of physicochemical and biological parameters between replicated outdoor freshwater lentic mesocosms.

Micro- and mesocosms are frequently required in regulatory procedures of aquatic risk assessment for pesticides. However, many questions are still a matter of debate with regard to the use of these systems for environmental risk assessment, especially considering the inter-system variability of the measured parameters and its consequences on experimental design and data analysis. In this paper, variability of physico-chemical and biological parameters measured during two long-term experiments (8 to 9 months) in uncontaminated outdoor freshwater lentic mesocosms (8 m3) is analysed. Consequences on the design of ecotoxicity tests in mesocosms and on data analysis are also addressed. Water temperature, pH, dissolved oxygen concentration and concentration of suspended solids exhibited a very low variability whereas nutrient concentrations displayed elevated levels of variability. Among biological parameters, those measured at the individual level were less variable than those measured at the community level. Functional descriptors frequently exhibited a lower inter-mesocosm variability than structural descriptors. Aggregation of data proved to significantly reduce inter-mesocosm variability. The results indicate that univariate statistical methods may be used for physico-chemical or species-level (e.g. biometric parameters) data which exhibit a moderate inter-mesocosm variability. The use of multivariate techniques is suggested for other levels of investigation. Nevertheless, variability is not sufficient to identify useful parameters. The sensitivity towards chemicals and ecological relevance of descriptors within the experimental context must also be considered.

Ammonia↗