COSMIN Risk of Bias tool to assess the quality of studies on reliability or measurement error of outcome measurement instruments: a Delphi study.

BACKGROUND: Scores on an outcome measurement instrument depend on the type and settings of the instrument used, how instructions are given to patients, how professionals administer and score the instrument, etc. The impact of all these sources of variation on scores can be assessed in studies on reliability and measurement error, if properly designed and analyzed. The aim of this study was to develop standards to assess the quality of studies on reliability and measurement error of clinician-reported outcome measurement instruments, performance-based outcome measurement instrument, and laboratory values. METHODS: We conducted a 3-round Delphi study involving 52 panelists. RESULTS: Consensus was reached on how a comprehensive research question can be deduced from the design of a reliability study to determine how the results of a study inform us about the quality of the outcome measurement instrument at issue. Consensus was reached on components of outcome measurement instruments, i.e. the potential sources of variation. Next, we reached consensus on standards on design requirements (n = 5), standards on preferred statistical methods for reliability (n = 3) and measurement error (n = 2), and their ratings on a four-point scale. There was one term for a component and one rating of one standard on which no consensus was reached, and therefore required a decision by the steering committee. CONCLUSION: We developed a tool that enables researchers with and without thorough knowledge on measurement properties to assess the quality of a study on reliability and measurement error of outcome measurement instruments.

Development and content validation of measures assessing adherence barriers and behaviors for use in clinical care.

BACKGROUND: Providers are often unaware of poor adherence to prescribed medications for their patients with chronic diseases. OBJECTIVE: To develop brief, computer-administered patient-reported measures in English and Spanish assessing adherence behaviors and barriers. Design, Participants, and Main Measures: Item pools were constructed from existing measures of medication adherence behaviors and barriers, which informed development of a patient concept elicitation interview guide to identify medication adherence behavior and barrier-related concepts. Two hundred six patients either living with HIV (PLWH) or without were interviewed. Interviews were coded, concepts matched to item pool content, and new items were developed for novel concepts. A provider/investigator team highlighted clinically relevant items. Cognitive interviews were conducted with patients on final candidate items (n = 37). The instruments were administered to 2081 PLWH. KEY RESULTS: Behavioral themes from concept elicitation interviews included routines incorporating time of day, placement, visual cues, and intentionality to miss or skip doses. Barrier themes included health-related (e.g. depressed mood, feeling ill), attitudes/beliefs (e.g., need for medication), access (e.g., cost/insurance problems), and circumstantial barriers (e.g., lack of privacy, disruption of daily routine). The final instruments included 6 behavior items, and 1 barrier item with up to 23 response options. PLWH endorsed a mean (SD) of 3.5 (1.1) behaviors. The 201 PLWH who missed ≥2 doses in the previous week endorsed a mean (SD) of 3.1 (2.5) barriers. The intraclass correlation coefficient (ICC) for the numbers of behaviors endorsed in 61 PLWH after 4-16 days was 0.54 and for the number of barriers for the 20 PLWH with ≥2 missed doses the ICC was 0.89, representing fair and excellent test-retest reliability. CONCLUSION: Measures of medication adherence behaviors and barriers were developed for use with patients living with chronic diseases focusing on clinical relevance, brevity, and content validity for use in clinical care.

Circumstances Surrounding High-risk Sexual Experiences Among Primary Care Patients Living With and Without HIV.

INTRODUCTION: Rates of sexually transmitted infection (STI) are rising in the USA, yet STI risk remains under-addressed by providers, even in HIV care, and with high-risk patients. We interviewed primary care patients living with and without HIV regarding circumstances surrounding sexual risk behavior to identify opportunities for providers to address and reduce STI risk. METHODS: We conducted semi-structured 1:1 interviews with patients living with and without HIV reporting ≥ 1 sex partner and varying STI exposure risk in the past 12 months from four geographically diverse US HIV and primary care clinics. We audio-recorded, transcribed, and coded interviews by circumstance type, using double-coding to ensure inter-coder reliability. We used Fisher's exact and T tests to determine associations with demographic/risk factors. RESULTS: Patients (n = 91) identified a mean of 3 of 11 circumstances. These included substance use (54%), desire for physical/emotional intimacy (48%), lack of HIV/STI status disclosure (44%), psychological drivers (i.e., coping, depression; 38%), personal dislike of condoms (22%), partner condom dislike/refusal (19%), receiving payment for sex (13%), and condom unavailability (9%). Higher proportions of those who were high STI-exposure risk patients, defined as those with ≥ 2 sex partners in the past 3 months reporting never or sometimes using condoms, reported disliking condoms (p = .006); higher proportions of the high-risk and moderate-risk (≥ 2 partners and condom use "most of the time") groups reported substance use as a circumstance (p = .04). CONCLUSION: Circumstances surrounding perceived STI exposure risk were diverse, often overlapping, and dependent on internal, environmental, and partner-related factors and inadequate communication. Meaningful care-based interventions regarding HIV/STI transmission behavior must address the diversity and interplay of these factors.

COSMIN methodology for evaluating the content validity of patient-reported outcome measures: a Delphi study.

BACKGROUND: Content validity is the most important measurement property of a patient-reported outcome measure (PROM) and the most challenging to assess. Our aims were to: (1) develop standards for evaluating the quality of PROM development; (2) update the original COSMIN standards for assessing the quality of content validity studies of PROMs; (3) develop criteria for what constitutes good content validity of PROMs, and (4) develop a rating system for summarizing the evidence on a PROM's content validity and grading the quality of the evidence in systematic reviews of PROMs. METHODS: An online 4-round Delphi study was performed among 159 experts from 21 countries. Panelists rated the degree to which they (dis)agreed to proposed standards, criteria, and rating issues on 5-point rating scales ('strongly disagree' to 'strongly agree'), and provided arguments for their ratings. RESULTS: Discussion focused on sample size requirements, recording and field notes, transcribing cognitive interviews, and data coding. After four rounds, the required 67% consensus was reached on all standards, criteria, and rating issues. After pilot-testing, the steering committee made some final changes. Ten criteria for good content validity were defined regarding item relevance, appropriateness of response options and recall period, comprehensiveness, and comprehensibility of the PROM. DISCUSSION: The consensus-based COSMIN methodology for content validity is more detailed, standardized, and transparent than earlier published guidelines, including the previous COSMIN standards. This methodology can contribute to the selection and use of high-quality PROMs in research and clinical practice.

COSMIN guideline for systematic reviews of patient-reported outcome measures.

PURPOSE: Systematic reviews of patient-reported outcome measures (PROMs) differ from reviews of interventions and diagnostic test accuracy studies and are complex. In fact, conducting a review of one or more PROMs comprises of multiple reviews (i.e., one review for each measurement property of each PROM). In the absence of guidance specifically designed for reviews on measurement properties, our aim was to develop a guideline for conducting systematic reviews of PROMs. METHODS: Based on literature reviews and expert opinions, and in concordance with existing guidelines, the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) steering committee developed a guideline for systematic reviews of PROMs. RESULTS: A consecutive ten-step procedure for conducting a systematic review of PROMs is proposed. Steps 1-4 concern preparing and performing the literature search, and selecting relevant studies. Steps 5-8 concern the evaluation of the quality of the eligible studies, the measurement properties, and the interpretability and feasibility aspects. Steps 9 and 10 concern formulating recommendations and reporting the systematic review. CONCLUSIONS: The COSMIN guideline for systematic reviews of PROMs includes methodology to combine the methodological quality of studies on measurement properties with the quality of the PROM itself (i.e., its measurement properties). This enables reviewers to draw transparent conclusions and making evidence-based recommendations on the quality of PROMs, and supports the evidence-based selection of PROMs for use in research and in clinical practice.

Initial development and pilot testing of observer-reported outcomes (ObsROs) for children with cystic fibrosis ages 0-11years.

PURPOSE: Patient-reported outcomes are important clinical trial endpoints. Young children may not be able to reliably report on how they feel or function, so observer-reported outcomes (ObsROs) may be more appropriate for them. The purpose of this study was to develop and pilot field test electronic parent-reported observational instruments for children with cystic fibrosis (CF) 0-6 and 7-11years of age. METHODS: We performed concept elicitation interviews with parents of children with CF ≤11years of age to elicit the respiratory signs they could observe at baseline and during an acute respiratory illness. The resulting instruments were refined based on interviews with parents and clinicians. We conducted a pilot field test to evaluate test-retest reliability and the ability of items to distinguish well and sick periods. RESULTS: The instruments consist of 17 items assessing respiratory signs and observable CF-related impacts. Test-retest reliability was acceptable for both age groups but discrimination was low for ages 7-11, likely reflecting less direct observation of older children by their parents. CONCLUSIONS: An ObsRO for children with CF ages 0-6 appears promising, while self-report may be more appropriate for children >6years of age. Next steps for the 0-6year old instrument will be utilizing it as an exploratory endpoint in clinical trials to enable item reduction, scale development, and further reliability and validity testing. Ultimately, this ObsRO could be a promising endpoint for early intervention trials in young children with CF.

COSMIN Risk of Bias checklist for systematic reviews of Patient-Reported Outcome Measures.

PURPOSE: The original COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist was developed to assess the methodological quality of single studies on measurement properties of Patient-Reported Outcome Measures (PROMs). Now it is our aim to adapt the COSMIN checklist and its four-point rating system into a version exclusively for use in systematic reviews of PROMs, aiming to assess risk of bias of studies on measurement properties. METHODS: For each standard (i.e., a design requirement or preferred statistical method), it was discussed within the COSMIN steering committee if and how it should be adapted. The adapted checklist was pilot-tested to strengthen content validity in a systematic review on the quality of PROMs for patients with hand osteoarthritis. RESULTS: Most important changes were the reordering of the measurement properties to be assessed in a systematic review of PROMs; the deletion of standards that concerned reporting issues and standards that not necessarily lead to biased results; the integration of standards on general requirements for studies on item response theory with standards for specific measurement properties; the recommendation to the review team to specify hypotheses for construct validity and responsiveness in advance, and subsequently the removal of the standards about formulating hypotheses; and the change in the labels of the four-point rating system. CONCLUSIONS: The COSMIN Risk of Bias checklist was developed exclusively for use in systematic reviews of PROMs to distinguish this application from other purposes of assessing the methodological quality of studies on measurement properties, such as guidance for designing or reporting a study on the measurement properties.

Medication understanding among patients living with multiple chronic conditions: Implications for patient-reported measures of adherence.

BACKGROUND: Low health literacy is associated with poor medication adherence and poor health outcomes. Limited understanding of prescribed medications may decrease validity of patient-reported adherence measures. OBJECTIVES: To assess knowledge of names and purposes of prescribed medications among patients with multiple chronic conditions. METHODS: Individual interviews were conducted with a convenience sample of patients from six U.S. primary care clinics. Participants (n = 57) were English and/or Spanish-speaking patients prescribed 3+ medications for chronic conditions, for which non-adherence may lead to disability or death. In individual interviews, patients were asked to name their medications, explain the purpose of each, and to explain how they distinguish them from one another. Interviews were audio recorded, transcribed, and coded; coded content was quantified by 1) whether or not the patient could name medications; 2) method of categorizing medications; 3) whether or not the purpose of the medication was understood. Descriptive statistics were compiled using Fisher's exact test to determine the relationship between patient knowledge and medication characteristics. RESULTS: Thirty percent of patients could not name at least one of their medications; 19% did not know their purpose; 30% held misconceptions about the purpose of one or more medications. There was no significant difference in ability to name medications or state their medication's purpose between patients using medi-sets, pre-packaged rolls, or blister packs, and patients who stored pills in their original containers (p = 0.56 and p = 0.73, respectively), or across demographic groups (p = 0.085 to 0.767). CONCLUSIONS: Many patients demonstrated difficulty identifying the name and purpose of prescribed medications; this did not differ by demographic group or medication storage type. Patients may benefit from routine review of medications with their provider in order to improve health literacy, outcomes, and patient-reported adherence measurement.

Validity assessment of the PROMIS fatigue domain among people living with HIV.

PURPOSE: To evaluate psychometric characteristics and cross-sectional and longitudinal validity of the 7-item PROMIS® Fatigue Short Form and additional fatigue items among people living with HIV (PLWH) in a nationally distributed network of clinics collecting patient reported data at the time of routine clinical care. METHODS: Cross-sectional and longitudinal fatigue data were collected from September 2012 through April 2013 across clinics participating in the Centers for AIDS Research Network of Integrated Clinical Systems (CNICS). We analyzed data regarding psychometric characteristics including simulated computerized adaptive testing and differential item functioning, and regarding associations with clinical characteristics. RESULTS: We analyzed data from 1597 PLWH. Fatigue was common in this cohort. Scores from the PROMIS® Fatigue Short Form and from the item bank had acceptable psychometric characteristics and strong evidence for validity, but neither performed better than shorter instruments already integrated in CNICS. CONCLUSIONS: The PROMIS® Fatigue Item Bank is a valid approach to measuring fatigue in clinical care settings among PLWH, but in our analyses did not perform better than instruments associated with less respondent burden.

Next Generation Multiresponsive Nanocarriers for Targeted Drug Delivery to Cancer Cells.

C-H bond activation of 2-methoxyethylamino-bis(phenolate)-yttrium catalysts allowed the synthesis of BAB block copolymers comprised of 2-vinylpyridine (2VP; monomer A) and diethylvinylphosphonate (DEVP; monomer B) as the A and B blocks, respectively, by rare-earth-metal-mediated group-transfer polymerization (REM-GTP). The inherent multi-stimuli-responsive character and drug-loading and -release capabilities were observed to be dependent on the chain length and monomer ratios. Cytotoxicity assays revealed the biocompatibility and nontoxic nature of the obtained micelles toward ovarian cancer (HeLa) cells. The BAB block copolymers effectively encapsulated, transported, and released doxorubicin (DOX) within HeLa cells. REM-GTP enables access to previously unattainable vinylphosphonate copolymer structures, and thereby unlocks their full potential as nanocarriers for stimuli-responsive drug delivery in HeLa cells. The self-evident consequence is the application of these new micelles as potent drug-delivery vehicles with reduced side effects in future cancer therapies.

Systematic review: patient-reported outcome measures in coeliac disease for regulatory submissions.

BACKGROUND: New therapeutics are moving into phase 3 clinical trials for the treatment of coeliac disease, a condition with no established therapies other than gluten-free diet. These trials will require a meaningful, validated and fit for purpose patient-reported outcome measure (PROM) to quantify the symptomatic improvement of patients. AIM: To evaluate existing PROMs for suitability in a Food and Drug Administration (FDA) approval trial for a coeliac disease therapeutic. METHOD: We performed a systematic search in five online databases (MedLine, EmBase, Web of Science, CENTRAL, CINAHL) for studies that enrolled patients with coeliac disease and used PROMs. Studies included in this review had to measure some PROM concept, be patient administered and based upon a previously validated instrument with published measurement properties. RESULTS: Our literature search identified 2706 unique records of which 199 ultimately qualified for abstraction. The majority of PROMs used in studies of coeliac disease was generic and did not measure numerous symptoms or concerns of interest to patients. Four PROMs were found to contain appropriate content for use in an FDA trial: the coeliac disease-specific modification of the Gastrointestinal Symptoms Rating Scale (CeD-GSRS), Psychological General Well-Being Index (PGWB), the Celiac Disease Symptom Diary (CDSD) and the Celiac Disease Patient Reported Outcome (CeD-PRO). The GSRS and PGWB are most often used together and are two of the most extensively used measures in coeliac disease. The CDSD and CeD-PRO were developed exclusively for trials in coeliac disease but have much less published information on their measurement properties. CONCLUSIONS: While we did not find PROMs that currently meet the stated expectations of the FDA for regulatory purposes, four PROMs (CeD-GSRS, PGWB, CDSD and CeD-PRO) appear to contain appropriate content and with modest additional validation work could meet scientific standards for valid and sensitive measures of disease and treatment outcome. Specifically, what is needed for these instruments is an understanding of how sensitive they are to real changes in-patient condition, how stable they are over a period of time when health status should not have changed (test-retest reliability) as well as how they correlate with other measures of patient functioning such as intestinal biopsy. All of these objectives could feasibly be accomplished over a short cohort study of patients with biopsy-defined coeliac disease undergoing gluten challenge.

Inclusion of patient-reported outcome measures in registered clinical trials: Evidence from ClinicalTrials.gov (2007-2013).

BACKGROUND: Patient reported outcomes (PROs) have gained a prominent place in clinical research. Previous estimates suggest that PRO measures are used in 14% of clinical trials. Online registries, such as ClinicalTrials.gov, may be useful in evaluating extent of PRO use. PURPOSE: To estimate the proportion of clinical trials using at least one PRO measure and to examine associations between trial characteristics and use of PRO measures. METHODS: A copy of the ClinicalTrials.gov database was made, containing all data from November 2007 to December 2013. Content was searched for use of PRO measures. Multivariable logistic regression was used to investigate possible associations between trial-level characteristics and use of PRO measures. RESULTS: Of 96,736 registered trials, 26,337 (27%) were identified as using one or more PRO measures. Among oncology trials, 29% (3947/13,584) were identified as using a PRO measure, compared to 27% (22,390/83,152) of non-oncology trials. A greater proportion of trials using PRO measures were more likely to be sponsored by university/research organizations (29%) or the US government (33%), compared to industry (22%); Phase III (35%); non-randomized (32%); and evaluating devices (30%), procedures (31%) or behaviors (50%), compared to drugs (24%). Fewer were FDA-regulated (23%). CONCLUSIONS: Evidence suggests that between 2007 and 2013, there has been an increase in the number of trials that use a PRO measure, particularly in oncology trials. With initiatives such as the Patient-Focused Drug Development and FDA PRO Guidance, the trend in the use of PRO measures in clinical research will likely increase further.

Photoluminescent silicon nanocrystal-polymer hybrid materials via surface initiated reversible addition-fragmentation chain transfer (RAFT) polymerization.

Silicon-polymer core-shell hybrid materials are obtained via surface initiated reversible addition-fragmentation chain transfer (RAFT) polymerization from photoluminescent silicon nanocrystals (SiNCs). Polymer grafted SiNCs and free polymers in solution are separated using ultracentrifugation. The polymerization on the surface proceeds in a living manner which is confirmed via GPC, DLS and TGA measurements. This method was applied to various other monomers. The obtained materials all show bright red photoluminescence originating from the SiNC core.

Indole alkaloids from Fischerella inhibit vertebrate development in the zebrafish (Danio rerio) embryo model.

Cyanobacteria are recognized producers of toxic or otherwise bioactive metabolite associated, in particular, with so-called "harmful algal blooms" (HABs) and eutrophication of freshwater systems. In the present study, two apparently teratogenic indole alkaloids from a freshwater strain of the widespread cyanobacterial genus, Fischerella (Stigonemataceae), were isolated by bioassay-guided fractionation, specifically using the zebrafish (Danio rerio) embryo, as a model of vertebrate development. The two alkaloids include the previously known 12-epi-hapalindole H isonitrile (1), and a new nitrile-containing variant, 12-epi-ambiguine B nitrile (2). Although both compounds were toxic to developing embryos, the former compound was shown to be relatively more potent, and to correlate best with the observed embryo toxicity. Related indole alkaloids from Fischerella, and other genera in the Stigonemataceae, have been widely reported as antimicrobial compounds, specifically in association with apparent allelopathy. However, this is the first report of their vertebrate toxicity, and the observed teratogenicity of these alkaloids supports a possible contribution to the toxicity of this widespread cyanobacterial family, particularly in relation to freshwater HABs and eutrophication.

Effects of a diabetes prevention programme on weight-specific quality of life in Latino youth.

OBJECTIVE: To examine the effects of a diabetes prevention programme on weight-specific Quality of Life (QOL) in obese Latino youth. METHODS: Fifteen obese Latino adolescents (body mass index % = 96.4 ± 1.2; age = 15.0 ± 1.0) completed a 12-week culturally grounded, community-based intervention designed to improve physical and psychosocial health. Weight-specific QOL was assessed by the Youth Quality of Life-Weight module and compared with age, sex and ethnicity-matched lean youth. RESULTS: At baseline, intervention youth exhibited significantly lower weight-specific QOL compared with lean youth (70.8 ± 5.4 vs. 91.2 ± 2.2, P = 0.002). However, following the intervention, total weight-specific QOL increased by 21.8% among obese youth (70.8 ± 5.4 to 86.2 ± 4.3, P < 0.001) and was no longer different from lean controls. Significant increases in weight-specific QOL were noted across all subdomains including self (45.7%), social (11.9%) and environmental (36.2%) despite the fact that weight did not change (90.6 ± 6.8 to 89.9 ± 7.2, P = 0.44). The improvements in QOL were maintained for up to 12 months after the intervention. CONCLUSION: Weight-specific QOL among obese Latino youth can be improved through lifestyle interventions to a level similar to lean peers. Further, weight loss may not be necessary to observe improvements in QOL.

Polymethoxy-1-alkenes from Aphanizomenon ovalisporum inhibit vertebrate development in the zebrafish (Danio rerio) embryo model.

Cyanobacteria are recognized producers of a wide array of toxic or otherwise bioactive secondary metabolites. The present study utilized the zebrafish (Danio rerio) embryo as an aquatic animal model of vertebrate development to identify, purify and characterize lipophilic inhibitors of development (i.e., developmental toxins) from an isolate of the freshwater cyanobacterial species, Aphanizomenon ovalisporum.Bioassay-guided fractionation led to the purification, and subsequent chemical characterization, of an apparent homologous series of isotactic polymethoxy-1-alkenes (1-6), including three congeners (4-6) previously identified from the strain, and two variants previously identified from other species (2 and 3), as well as one apparently novel member of the series (1). Five of the PMAs in the series (1-5) were purified in sufficient quantity for comparative toxicological characterization, and toxicity in the zebrafish embryo model was found to generally correlate with relative chain length and/or methoxylation. Moreover, exposure of embryos to a combination of variants indicates an apparent synergistic interaction between the congeners. Although PMAs have been identified previously in cyanobacteria, this is the first report of their apparent toxicity. These results, along with the previously reported presence of the PMAs from several cyanobacterial species, suggest a possibly widespread distribution of the PMAs as toxic secondary metabolites and warrants further chemical and toxicological investigation.

Clinical benefit in patients with metastatic bone disease: results of a phase 3 study of denosumab versus zoledronic acid.

BACKGROUND: Patients with metastatic bone disease are living longer in the metastatic stage due to improvements in cancer therapy, making strategies to prevent the aggravation of bone disease and its complications, such as skeletal-related events (SREs) and pain, increasingly important. PATIENTS AND RESULTS: In this phase 3 trial in patients with advanced cancer (excluding breast and prostate cancer) or multiple myeloma, denosumab reduced the risk of radiation to bone by 22% relative to zoledronic acid (P = 0.026), prevented worsening of pain and pain interference (2-point increase in Brief Pain Inventory score; P < 0.05 versus zoledronic acid), and reduced the frequency of a shift from no/weak opioid analgesic use to strong opioids (P < 0.05 versus zoledronic acid at months 3-5). Denosumab delayed the time to moderate-to-severe pain compared with zoledronic acid in patients with mild or no pain at the baseline (P = 0.04), supporting early treatment. Health-related quality-of-life scores were similar in both groups. The number needed to treat to avoid one SRE for denosumab was 3 patient-years versus placebo and 10 patient-years versus zoledronic acid. CONCLUSION: The use of denosumab was associated with better prevention of the complications of metastatic bone disease secondary to solid tumors or multiple myeloma versus zoledronic acid.

Effects of cyanobacterial lipopolysaccharides from microcystis on glutathione-based detoxification pathways in the zebrafish (Danio rerio) embryo.

Cyanobacteria ("blue-green algae") are recognized producers of a diverse array of toxic secondary metabolites. Of these, the lipopolysaccharides (LPS), produced by all cyanobacteria, remain to be well investigated. In the current study, we specifically employed the zebrafish (Danio rerio) embryo to investigate the effects of LPS from geographically diverse strains of the widespread cyanobacterial genus, Microcystis, on several detoxifying enzymes/pathways, including glutathione-S-transferase (GST), glutathione peroxidase (GPx)/glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT), and compared observed effects to those of heterotrophic bacterial (i.e., E. coli) LPS. In agreement with previous studies, cyanobacterial LPS significantly reduced GST in embryos exposed to LPS in all treatments. In contrast, GPx moderately increased in embryos exposed to LPS, with no effect on reciprocal GR activity. Interestingly, total glutathione levels were elevated in embryos exposed to Microcystis LPS, but the relative levels of reduced and oxidized glutathione (i.e., GSH/GSSG) were, likewise, elevated suggesting that oxidative stress is not involved in the observed effects as typical of heterotrophic bacterial LPS in mammalian systems. In further support of this, no effect was observed with respect to CAT or SOD activity. These findings demonstrate that Microcystis LPS affects glutathione-based detoxification pathways in the zebrafish embryo, and more generally, that this model is well suited for investigating the apparent toxicophore of cyanobacterial LPS, including possible differences in structure-activity relationships between heterotrophic and cyanobacterial LPS, and teleost fish versus mammalian systems.