Population receptive field tuning properties of visual cortex during childhood.

Visuospatial abilities such as contrast sensitivity and Vernier acuity improve until late in childhood, but the neural mechanisms supporting these changes are poorly understood. We tested to which extent this development might reflect improved spatial sensitivity of neuronal populations in visual cortex. To do this, we measured BOLD-responses in areas V1-V4 and V3a, whilst 6- to 12-year-old children and adults watched large-field wedge and ring stimuli in the MRI scanner, and then fitted population receptive field (pRF) tuning functions to these data (Dumoulin and Wandell, 2008). Cortical magnification and pRF tuning width changed with eccentricity at all ages, as expected. However, there were no significant age differences in pRF size, shape, cortical magnification, or map consistency in any visual region. These findings thus strongly suggest that spatial vision in late childhood is not substantially limited by the spatial tuning of neuronal populations in early visual cortex. Instead, improvements in performance may reflect more efficient read-out of spatial information in early visual regions by higher-level processing stages, or prolonged tuning to more complex visual properties such as orientation. Importantly, this in-depth characterisation of the pRF tuning profiles across childhood, paves the way for in-vivo-testing of atypical visual cortex development and plasticity.

The prognostic value of tumour-stroma ratio in primary breast cancer with special attention to triple-negative tumours: a review.

PURPOSE: There is a strong need to improve the prognostication of breast cancer patients in order to prevent over- and undertreatment, especially when considering adjuvant chemotherapy. Tumour stroma characteristics might be valuable in predicting disease progression. METHODS: Studies regarding the prognostic value of tumour-stroma ratio (TSR) in breast cancer are evaluated. RESULTS: A high stromal content is related to a relatively poor prognosis. The most pronounced prognostic effect of this parameter seems to be observed in the triple-negative breast cancer (TNBC) subtype. CONCLUSIONS: TSR assessment might represent a simple, fast and reproducible prognostic factor at no extra costs, and could possibly be incorporated into routine pathological diagnostics. Despite these advantages, a robust clinical validation of this parameter has yet to be established in prospective studies.

Exhaled breath profiles in the monitoring of loss of control and clinical recovery in asthma.

BACKGROUND: Asthma is a chronic inflammatory airway disease, associated with episodes of exacerbations. Therapy with inhaled corticosteroids (ICS) targets airway inflammation, which aims to maintain and restore asthma control. Clinical features are only modestly associated with airways inflammation. Therefore, we hypothesized that exhaled volatile metabolites identify longitudinal changes between clinically stable episodes and loss of asthma control. OBJECTIVES: To determine whether exhaled volatile organic compounds (VOCs) as measured by gas-chromatography/mass-spectrometry (GC/MS) and electronic nose (eNose) technology discriminate between clinically stable and unstable episodes of asthma. METHODS: Twenty-three patients with (partly) controlled mild to moderate persistent asthma using ICS were included in this prospective steroid withdrawal study. Exhaled metabolites were measured at baseline, during loss of control and after recovery. Standardized sampling of exhaled air was performed, after which samples were analysed by GC/MS and eNose. Univariate analysis of covariance (ANCOVA), followed by multivariate principal component analysis (PCA) was used to reduce data dimensionality. Next paired t tests were utilized to analyse within-subject breath profile differences at the different time-points. Finally, associations between exhaled metabolites and sputum inflammation markers were examined. RESULTS: Breath profiles by eNose showed 95% (21/22) correct classification for baseline vs loss of control and 86% (19/22) for loss of control vs recovery. Breath profiles using GC/MS showed accuracies of 68% (14/22) and 77% (17/22) for baseline vs loss of control and loss of control vs recovery, respectively. Significant associations between exhaled metabolites captured by GC/MS and sputum eosinophils were found (Pearson r≥.46, P<.01). CONCLUSIONS & CLINICAL RELEVANCE: Loss of asthma control can be discriminated from clinically stable episodes by longitudinal monitoring of exhaled metabolites measured by GC/MS and particularly eNose. Part of the uncovered biomarkers was associated with sputum eosinophils. These findings provide proof of principle for monitoring and identification of loss of asthma control by breathomics.

Internalization of Escherichia coli O157:H7 gfp+ in rocket and Swiss chard baby leaves as affected by abiotic and biotic damage.

Internalization of human pathogens in edible parts of vegetables eaten raw is a major concern, since once internalized they are protected from sanitizing treatments. In this study, we examined the invasion of gfp-labelled Escherichia coli O157:H7 into intact and biotically (infection with Xanthomonas campestris/Pseudomonas syringae) and abiotically (grating with silicon carbide) damaged leaves of wild rocket (Diplotaxis tenuifolia) and Swiss chard (Beta vulgaris subsp. cicla) using laser scanning confocal microscopy. Bacterial cells were found in internal locations of the tissue, irrespective of tissue health status. Contaminated leaf sections of biotically and abiotically damaged wild rocket leaves showed higher susceptibility to microbial invasion, while the pathogen was internalized in greater numbers into intact Swiss chard leaf sections when abiotically, but not biotically, damaged. The greatest differences were observed between the plant species; after surface sanitization, E. coli O157:H7 was still detected in wild rocket leaves, but not in Swiss chard leaves. SIGNIFICANCE AND IMPACT OF THE STUDY: Contamination of leafy vegetables with Escherichia coli O157:H7 is a growing problem, as reported outbreaks are increasing. However, establishment of this human pathogen in the phyllosphere is not completely understood. Using laser scanning confocal microscopy, we demonstrated that E. coli O157:H7gfp+ can invade plant tissue of Swiss chard and wild rocket leaves and that the bacterium is more sensitive to surface sanitization of Swiss chard leaves. Damage to leaf tissue promoted leaf invasion, but the nature of the damage (abiotic or biotic) and plant species had an impact.

[Fatal cerebral oedema during the treatment of diabetic ketoacidosis in an adult male]. / Fataal hersenoedeem bij behandeling van een volwassene met diabetische ketoacidose.

Diabetic ketoacidosis is relatively common, but the optimal treatment of this condition is still controversial. Cerebral oedema is a rare, but potentially fatal complication. We present the case of an adult patient who presented with de novo diabetic ketoacidosis that was complicated by cerebral oedema during treatment. In this article we discuss factors that may have played a role in the development of this complication. A prolonged hyperosmolar state in diabetic ketoacidosis may increase the risk of cerebral oedema as a result of cerebral compensatory mechanisms. In this group of patients, liberal doses of insulin, fluids and bicarbonate may lead to a decrease in the effective serum osmolarity which can lead to water shifts in the cerebrum. We suggest several adjustments to current treatment guidelines for patients with diabetic ketoacidosis who have undergone a prolonged period of hyperosmolar derangement, with the aim of decreasing the risk of cerebral oedema.

[A woman with hyperpigmentation and dark urine]. / Een vrouw met hyperpigmentatie en zwarte urine.

A 54-year-old patient was evaluated because of fever shortly after she had started treatment of a BRAF-mutated melanoma with BRAF- and MEK-inhibitors. Diffuse hyperpigmentation of the skin was noted as an incidental finding. She also had darkly coloured urine. This hyperpigmentation was most likely the result of diffuse cutaneous melanosis secondary to advanced melanoma. This complication results from the release of melanin or its precursor molecules into the systemic circulation. Although diffuse cutaneous melanosis is commonly regarded as an ominous prognostic sign, this patient has so far responded well to targeted therapy.

An early innate response underlies severe influenza-induced exacerbations of asthma in a novel steroid-insensitive and anti-IL-5-responsive mouse model.

BACKGROUND: Acute worsening of asthma symptoms (exacerbation) is predominantly triggered by respiratory viruses, with influenza causing the most severe exacerbations. The lack of an adequate animal model hampers mechanistic insight and the development of new therapeutics. AIM: We developed and characterized a robust, consistent, and reproducible mouse model of severe exacerbation of chronic allergic asthma. METHODS: Chronic allergic airway inflammation was induced following a house dust mite (HDM) sensitization protocol. HDM-sensitized mice and controls were infected with influenza virus A/X31 H3N2 and either or not treated with inhaled fluticasone propionate (FP), systemic corticosteroids (Pred), or anti-IL-5. Mice were killed at different time points after infection: Cellular accumulation and cytokines levels in the airways, PenH as a measure of airway hyper-responsiveness (AHR), and lung histology and viral replication were assessed. RESULTS: Infection with low-dose A/X31 H3N2 led to prolonged deterioration of lung function, aggravated mucus production, peri-vascular, peri-bronchial, and allergic inflammation that was unresponsive to inhaled corticosteroids, but responsive to systemic corticosteroids. The exacerbation was preceded at 14 h after virus exposure by a marked innate, but no Th2 and Th1 response subsequently followed by enhanced numbers of eosinophils, neutrophils, dendritic, and T cells into the lung lumen, parenchyma, and draining lymph nodes in HDM-sensitized mice. Anti-IL-5 treatment attenuated eosinophils and prevented the X31-induced exacerbation. CONCLUSIONS: Together, these findings indicate that an early innate response that involves eosinophils underlies the exacerbation. This model recapitulates all major features of severe asthma exacerbations and can serve to discern driving mechanisms and promote the development of novel therapeutics.

Quality assessment of estrogen receptor and progesterone receptor testing in breast cancer using a tissue microarray-based approach.

Assessing hormone receptor status is an essential part of the breast cancer diagnosis, as this biomarker greatly predicts response to hormonal treatment strategies. As such, hormone receptor testing laboratories are strongly encouraged to participate in external quality control schemes to achieve optimization of their immunohistochemical assays. Nine Dutch pathology departments provided tissue blocks containing invasive breast cancers which were all previously tested for estrogen receptor and/or progesterone receptor expression during routine practice. From these tissue blocks, tissue microarrays were constructed and tested for hormone receptor expression. When a discordant result was found between the local and TMA result, the original testing slide was revised and staining was repeated on a whole-tissue block. Sensitivity and specificity of individual laboratories for testing estrogen receptor expression were high, with an overall sensitivity and specificity [corrected] of 99.7 and 95.4%, respectively. Overall sensitivity and specificity of progesterone receptor testing were 94.8 and 92.6%, respectively. Out of 96 discordant cases, 36 cases would have been concordant if the recommended cut-off value of 1% instead of 10% was followed. Overall sensitivity and specificity of estrogen and progesterone receptor testing were high among participating laboratories. Continued enrollment of laboratories into quality control schemes is essential for achieving and maintaining the highest standard of care for breast cancer patients.

Disorganised stroma determined on pre-treatment breast cancer biopsies is associated with poor response to neoadjuvant chemotherapy: Results from the NEOZOTAC trial.

INTRODUCTION: The tumor-associated stroma is of importance for tumor progression and is generally accepted to have a significant influence on patient prognosis. However, little is known regarding specific features of tumor-associated stromal tissues and response to (neoadjuvant) chemotherapy. This study investigated the predictive value of extracellular matrix organization on response to chemotherapy in patients treated in the NEOZOTAC trial. METHODS: Stromal organisation was analyzed via a simple method using image analysis software on hematoxylin and eosin (H&E)-stained slides from primary tumor biopsies collected as part of the NEOZOTAC trial. Heidenhain's AZAN trichrome-stained slides were also analyzed for comparison of collagen evaluation. Sections were stained for phospho-Smad2 (pS2) in order to determine the relationship of TGF-ß signaling with stromal organization. RESULTS: A statistically significant relationship was observed between stroma consisting of organised collagen and pathological response to neoadjuvant chemotherapy (Odds Ratio 0.276, 95%CI 0.124-0.614, P = 0.002). This parameter was also related to ER-status (P = 0.003), clinical tumor -status (P = 0.041), nodal status (P = 0.029) and pS2 status (P = 0.025). Correlation between stromal organisation determined on H&E-stained and AZAN-stained tissue sections was high (Pearson's correlation coefficient = 0.806). CONCLUSION: Intratumoral stromal organisation determined using pre-treatment breast cancer biopsies was related to pathological response to chemotherapy. This parameter might play a role in the management of breast cancer for identifying those patients that are likely to benefit from neoadjuvant chemotherapy.

Quantitative assessment of lymph vascular space invasion (LVSI) provides important prognostic information in node-negative breast cancer.

BACKGROUND: Some studies investigating the prognostic value of lymph vascular space invasion (LVSI) have shown an association between LVSI and disease-free survival. Definitive criteria and optimal determination of this parameter remain unclear, however, especially regarding the clinical relevance of LVSI quantification. PATIENTS AND METHODS: A subset of node-negative breast carcinomas from premenopausal patients from the European Organization for the Research and Treatment of Cancer trial 10854 (assessing efficacy of perioperative chemotherapy patients with T1-T3, N0-2, and M0 breast cancer (BC) was selected and scored for LVSI. In 358 evaluable breast carcinomas, the number of LVSI foci and tumor cells was determined in the largest tumor embolus within the lymph vessels. These two parameters were multiplied to calculate the LVSI tumor burden (LVSI TB). The optimal cutoff for this parameter was calculated in a test set (N = 120), tested in a validation set (N = 238), and compared with simple quantitation of the number of LVSI foci. RESULTS: Tumors with a single LVSI focus are not associated with increased risk for relapse [hazard ratio (HR) 1.423, 95% confidence interval (CI) 0.762-2.656]. The LVSI TB had higher sensitivity and specificity compared with simple determination of the number of LVSI foci. LVSI TB was independently associated with disease-free survival in the validation set (HR 2.366, 95% CI 1.369-4.090, P = 0.002) in multivariate analysis and provided prognostic information in both the low- and high-risk node-negative BC groups (P < 0.001 and P = 0.007, respectively). CONCLUSION: The determination of the number of LVSI foci multiplied by the number of tumor cells gives the most reliable quantitative assessment of this parameter, which can provide prognostic information in node-negative BC.

Prognostic significance of the tumor-stroma ratio: validation study in node-negative premenopausal breast cancer patients from the EORTC perioperative chemotherapy (POP) trial (10854).

The tumor-stroma ratio has previously been shown to be prognostic for patients with invasive breast cancer. We present a validation study to assess the prognostic significance in lymph node-negative, premenopausal patients from the perioperative chemotherapy trial (POP trial, 10854) conducted by the European Organization for Research and Treatment of Cancer. The POP trial assessed the efficacy of one course of perioperative chemotherapy (consisting of fluorouracil, doxorubicin, and cyclophosphamide). Hematoxylin and eosin (H&E) stained sections were retrieved from a subset of premenopausal, node-negative patients from this trial and were scored for the percentage of intra-tumoral stroma. The tumor-stroma ratio was associated with disease-free survival in univariate and multivariate analysis. Tumors with a high tumor-stroma ratio had an increased hazard of 1.853 for disease relapse (95 %CI 1.327-2.585, P < 0.001) independent of other parameters. Combining other parameters with the tumor-stroma ratio improved risk stratification. For triple-negative tumors, the tumor-stroma ratio was associated with an increased hazard for disease relapse, independent of other parameters (HR 2.711, 95 %CI 1.111-6.614, P = 0.028). The tumor-stroma ratio was also independently associated with locoregional recurrence even in breast cancer patients ≤40 years of age (HR 2.201, 95 %CI 1.038-4.669, P = 0.040). This study validates the prognostic value of the tumor-stroma ratio. This parameter can be easily assessed on HE slides and can be implemented next to pathological staging reports to determine patient prognosis.

The prognostic role of TGF-ß signaling pathway in breast cancer patients.

BACKGROUND: The transforming growth factor-ß (TGF-ß) pathway has dual effects on tumor growth. Seemingly, discordant results have been published on the relation between TGF-ß signaling markers and prognosis in breast cancer. Improved prognostic information for breast cancer patients might be obtained by assessing interactions among TGF-ß signaling biomarkers. PATIENTS AND METHODS: The expression of nuclear Smad4, nuclear phosphorylated-Smad2 (p-Smad2), and the membranous expression of TGF-ß receptors I and II (TßRI and TßRII) was determined on a tissue microarray of 574 breast carcinomas. Tumors were stratified according to the Smad4 expression in combination with p-Smad2 expression or Smad4 in combination with the expression of both TGF-ß receptors. RESULTS: Tumors with high expression of TßRII, TßRI and TßRII, and p-Smad2 (P = 0.018, 0.005, and 0.022, respectively), and low expression of Smad4 (P = 0.005) had an unfavorable prognosis concerning progression-free survival. Low Smad4 expression combined with high p-Smad2 expression or low expression of Smad4 combined with high expression of both TGF-ß receptors displayed an increased hazard ratio of 3.04 [95% confidence interval (CI) 1.390-6.658] and 2.20 (95% CI 1.464-3.307), respectively, for disease relapse. CONCLUSIONS: Combining TGF-ß biomarkers provides prognostic information for patients with stage I-III breast cancer. This can identify patients at increased risk for disease recurrence that might therefore be candidates for additional treatment.

Reliability of core needle biopsy for determining ER and HER2 status in breast cancer.

BACKGROUND: Several studies have assessed the concordance of estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) status between core needle biopsy (CNB) and resection specimens, usually in small patient series and with discordant results. PATIENTS AND METHODS: ER and HER2 status determined on CNB and tissue micro-arrays of resected tumors were compared for patients treated at the Leiden University Medical Center (LUMC). When results were discordant, whole-sized slides were analyzed. Additionally, literature was searched for published patient series and combined with our data to assess the concordance of ER and HER2 determination between CNB and resection specimens. RESULTS: In the LUMC series, concordance for ER status was 99.1%. Combined concordance from 20 studies and the LUMC patient series was 93.7%. For HER2 testing, concordance was 96.2% for patients in the LUMC series. Our study and three others have investigated the concordance when HER2 was determined according to the American Society of Clinical Oncology and College of Pathology guidelines and overall concordance was 97.8%. CONCLUSIONS: Concordance between CNB and surgical specimens was high for both ER and HER2 testing. However, we recommend retesting ER-negative CNB results on the surgical specimen and performing in situ hybridization assays on HER2 immunohistochemistry 3+ CNBs to confirm HER2 status.

No detectable beneficial systemic immunomodulatory effects of a specific synbiotic mixture in infants with atopic dermatitis.

BACKGROUND: In a murine model of allergic inflammation, Bifidobacterium breve M-16V has been shown to reduce IL-4 and IgE by inducing IL-10 and IFN-γ. However, it remains unknown whether this strain has the same effect in humans with allergic disease. OBJECTIVE: To determine the effects of Bifidobacterium breve M-16V combined with a prebiotic oligosaccharide mixture (synbiotic) on atopic markers, ex vivo cytokine production by peripheral blood mononuclear cells (PBMCs) and circulating regulatory T cell percentage in infants with atopic dermatitis. METHODS: In a double-blind, placebo-controlled multi-centre trial, 90 infants with atopic dermatitis, age <7 months, were randomized to receive an infant formula with Bifidobacterium breve M-16V and a mixture of short chain galactooligosaccharides and long chain fructooligosaccharides (Immunofortis(®) ), or the same formula without synbiotics during 12 weeks. At week 0 and 12, plasma levels of IL-5, IgG1, IgG4, CTACK and TARC, ex vivo cytokine responses by PBMCs and percentage of regulatory T cells, were determined. RESULTS: There were no significant differences between the synbiotic and the placebo group in IL-5, IgG1, IgG4, CTACK and TARC levels and ex vivo cytokine production by anti-CD3/anti-CD28-stimulated PBMCs. With allergen-specific stimuli, we found a decreased IL-12p40/70 and IL-12p70 production in response to egg allergen (P = 0.04 and P = 0.01, respectively) and decreased IL-12p70 production in response to peanut allergen (P = 0.003) in the synbiotic compared with the placebo group. Circulating regulatory T cell percentage did not significantly differ between the groups. CONCLUSIONS AND CLINICAL RELEVANCE: This synbiotic mixture has no detectable effect on plasma levels of the analysed atopic disease markers, ex vivo cytokine production and circulating regulatory T cell percentage in infants with atopic dermatitis, besides down-regulation of IL-12 production in egg- and peanut-stimulated PBMCs. These results do not support the use of this synbiotic in clinical practice.

Exhaled air molecular profiling in relation to inflammatory subtype and activity in COPD.

Eosinophilic inflammation in chronic obstructive pulmonary disease (COPD) is predictive for responses to inhaled steroids. We hypothesised that the inflammatory subtype in mild and moderate COPD can be assessed by exhaled breath metabolomics. Exhaled compounds were analysed using gas chromatography and mass spectrometry (GC-MS) and electronic nose (eNose) in 28 COPD patients (12/16 Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I/II, respectively). Differential cell counts, eosinophil cationic protein (ECP) and myeloperoxidase (MPO) were measured in induced sputum. Relationships between exhaled compounds, eNose breathprints and sputum inflammatory markers were analysed and receiver operating characteristic (ROC) curves were constructed. Exhaled compounds were highly associated with sputum cell counts (eight compounds with eosinophils, 17 with neutrophils; p < 0.01). Only one compound (alkylated benzene) overlapped between eosinophilic and neutrophilic profiles. GC-MS and eNose breathprints were associated with markers of inflammatory activity in GOLD stage I (ECP: 19 compounds, p < 0.01; eNose breathprint r = 0.84, p = 0.002) (MPO: four compounds, p < 0.01; eNose r = 0.72, p = 0.008). ROC analysis for eNose showed high sensitivity and specificity for inflammatory activity in mild COPD (ECP: area under the curve (AUC) 1.00; MPO: AUC 0.96) but not for moderate COPD. Exhaled molecular profiles are closely associated with the type of inflammatory cell and their activation status in mild and moderate COPD. This suggests that breath analysis may be used for assessment and monitoring of airway inflammation in COPD.

Discordances in ER, PR and HER2 receptors after neoadjuvant chemotherapy in breast cancer.

Neoadjuvant chemotherapy (NAC) for breast cancer is evolving and subsequent adjuvant systemic treatment is mainly based on the presence of the Estrogen (ER) receptor, Progesterone (PR) receptor and Human Epidermal growth factor Receptor 2 (HER2) status on the core needle biopsy prior to treatment. It is not well known whether these biomarkers change after NAC, requiring a change in further adjuvant systemic treatment. A review of the literature (PubMed search) revealed 32 relevant studies that investigated the concordance of the hormone receptors (ER and/or PR) and HER2 after NAC with or without trastuzumab. Discordance of the hormone receptor status was reported in four out of eight studies in 8-33% of the patients. About half of the studies that tested the ER and PR receptor status separately reported discordances of 2.5-17% and 5.9-51.7% respectively. Studies that concluded that ER and/or PR receptor remained stable after NAC were performed with evidently lower number of patients compared to studies that reported a change. Good concordance of the HER2 amplification tested with FISH was reported, although the HER2 expression measured with immunohistochemistry was more discordant. A switch to a negative HER2 receptor in up to 43% of the patients was reported when NAC was combined with trastuzumab. Until more comparable studies are being published, retesting the receptor status of the residual tumor after NAC should be considered in order to improve future tailored adjuvant therapies.

First-line chemotherapy for malignant peripheral nerve sheath tumor (MPNST) versus other histological soft tissue sarcoma subtypes and as a prognostic factor for MPNST: an EORTC soft tissue and bone sarcoma group study.

BACKGROUND: the role of chemotherapy in advanced malignant peripheral nerve sheath tumor (MPNST) is unclear. PATIENTS AND METHODS: chemotherapy-naive soft tissue sarcomas (STS) patients treated on 12 pooled nonrandomized and randomized European Organization for Research and Treatment of Cancer Soft Tissue and Bone Sarcoma Group trials were retrospectively analyzed. Clinical outcomes, overall survival, progression-free survival (PFS) and response were determined for MPNST and other STS histotypes and compared. Additionally, prognostic factors within the MPNST population were defined. Studied cofactors were demographics, sarcoma history, disease extent and chemotherapy regimen. RESULTS: after a median follow-up of 4.1 years, 175 MPNST out of 2675 eligible STS patients were analyzed. Outcome was similar for MPNST versus other STS histotypes, with a response rate, median PFS and overall survival of 21% versus 22%, 17 versus 16 weeks and 48 versus 51 weeks, respectively. Performance status was an independent prognostic factor for overall survival. Chemotherapy regimen was an independent prognostic factor for response (P < 0.0001) and PFS (P = 0.009). Compared with standard first-line doxorubicin, the doxorubicin-ifosfamide regimen had the best response, whereas ifosfamide had the worst prognosis. CONCLUSION: this series indicates the role of chemotherapy in treatment of advanced MPNST. This first comparison showed similar outcomes for MPNST and other STS histotypes. The apparent superiority of the doxorubicin-ifosfamide regimen justifies further investigations of this combination in randomized trials.

Development and application of a sediment toxicity test using the benthic cladoceran Chydorus sphaericus.

This study reports on the development and application of a whole sediment toxicity test using a benthic cladoceran Chydorus sphaericus, as an alternative for the use of pelagic daphnids. A C. sphaericus laboratory culture was started and its performance under control conditions was optimised. The test was firstly validated by determining dose-response relationships for aqueous cadmium and copper and ammonia, showing a sensitivity of C. sphaericus (96 h LC(50) values of 594 microg Cd/L, 191 microg Cu/L and 46 mg ammonia/L at pH 8) similar to that of daphnids. Next, sediment was introduced into the test system and a series of contaminated sediments from polluted locations were tested. A significant negative correlation between survival and toxicant concentrations was observed. It is concluded that the test developed in the present study using the benthic cladoceran C. sphaericus is suitable for routine laboratory sediment toxicity testing.