Participatory action research.
This glossary aims to clarify some of the key concepts associated with participatory action research.
Decision Making↗
Biomedical subjects
Danielle Smith
Publications and source records attributed to Danielle Smith.
Evaluation of an integrated in vitro-in silico PBPK (physiologically based pharmacokinetic) model to provide estimates of human bioavailability.
PK express module is a physiologically based model of first pass metabolism, which integrates in vitro data with an in silico physiologically based pharmacokinetic (PBPK) model to predict human bioavailability (F(H)). There are three required inputs: FDp (Fraction dose absorbed, final parameter from iDEA absorption module), protein binding (fu) and disappearance kinetics in human hepatocytes. Caco-2 permeability, aqueous solubility (at multiple pH's), estimated dose and chemical structure are inputs required for the estimation of FDp (Norris et al., 2000; Stoner et al., 2004) and were determined for all compounds in our laboratory or obtained from literature. Protein binding data was collected from literature references and/or Pfizer database. Human hepatocyte data was generated in-house using an automated human hepatocyte method (using Tecan Genesis Workstation) as described previously (). Sixteen compounds (commercial and Pfizer compounds) were chosen to evaluate the PK express model and the bioavailability predicted from the module was compared with known clinical endpoints. For majority of the 16 compounds (approximately 80%), the PK express model F(H) values were comparable to the known human bioavailability (F(H)) (within 23.7 units of the known human (true) F, except for PF 3, PF 4, PF 6). In conclusion, the PK express model integrates a number of key readily available discovery parameters and provides estimates of human performance by integrating in silico and experimental variables built on a physiological based pharmacokinetic model. Information from this model in conjunction with other ADME data (e.g., P450 inhibition) will enable progression of most promising compounds for further in vivo PK and/or efficacy studies.
Biological Availability↗
Validation of a semi-automated human hepatocyte assay for the determination and prediction of intrinsic clearance in discovery.
An automated high throughput human hepatocyte assay has been established with a 96-well format using a Tecan Genesistrade mark Workstation. Validation of this assay was performed with nine commercially available compounds and an additional 10 Pfizer compounds with varying hepatic extraction ratios (E(H)) ranging from 0.02 to approximately 1. The incubation conditions in the automated assay are readily and precisely controlled and cell viability of over 80% was achieved in the automated assay further confirming its utility for absorption, distribution, metabolism, and excretion (toxicity) (ADME (T)) screening. The results of the nine commercial compounds correlate with both manually executed (R(2)=0.97) and literature reported experimental results (R(2)=0.93). Overall, measured E(H)s were within two-fold of the literature values for approximately 90% of the 19 compounds tested. Additionally, good inter- and intra-day reproducibility was observed for all the 19 compounds. In conclusion, an automated and robust assay suitable for simultaneously testing up to 48 compounds with multiple time points has been validated. Throughput of 192 compounds per run can be achieved using 384-well plates to meet increasing needs in drug discovery. Currently, this automated assay is used to support early discovery profiling towards lead optimization of various discovery targets/programs.
Cell Survival↗
Enhanced toxicity and cellular binding of a modified amyloid beta peptide with a methionine to valine substitution.
The amyloid beta peptide (Abeta) is toxic to neuronal cells, and it is probable that this toxicity is responsible for the progressive cognitive decline associated with Alzheimer's disease. However, the nature of the toxic Abeta species and its precise mechanism of action remain to be determined. It has been reported that the methionine residue at position 35 has a pivotal role to play in the toxicity of Abeta. We examined the effect of mutating the methionine to valine in Abeta42 (AbetaM35V). The neurotoxic activity of AbetaM35V on primary mouse neuronal cortical cells was enhanced, and this diminished cell viability occurred at an accelerated rate compared with Abeta42. AbetaM35V binds Cu2+ and produces similar amounts of H2O2 as Abeta42 in vitro, and the neurotoxic activity was attenuated by the H2O2 scavenger catalase. The increased toxicity of AbetaM35V was associated with increased binding of this mutated peptide to cortical cells. The M35V mutation altered the interaction between Abeta and copper in a lipid environment as shown by EPR analysis, which indicated that the valine substitution made the peptide less rigid in the bilayer region with a resulting higher affinity for the bilayer. Circular dichroism spectroscopy showed that both Abeta42 and AbetaM35V displayed a mixture of alpha-helical and beta-sheet conformations. These findings provide further evidence that the toxicity of Abeta is regulated by binding to neuronal cells.
Amyloid beta-Peptides↗
Ingestion of ethanol just prior to sleep onset impairs memory for procedural but not declarative tasks.
STUDY OBJECTIVES: The aim of Experiment 1 was to determine if moderate ethanol consumption at bedtime would result in memory loss for recently learned cognitive procedural and declarative tasks. The aim of Experiment 2 was to establish that the memory loss due to alcohol consumption at bedtime was due to the effect of alcohol on sleep states. DESIGN: In Experiment 1, participants were asked to learn a cognitive procedural task and a declarative task in the evening. Then, either the same evening or 2 nights later, they were asked to drink ethanol (0.7g/kg). Sleep was monitored for 3 days and re-testing of the tasks was done on the eighth day after training at the same time of day. In Experiment 2, subjects were asked to learn a cognitive procedural task (Tower of Hanoi) and a motor procedural task (Pursuit Rotor) in the late afternoon. Then one group was asked to drink ethanol (0.9 g/kg) right after task acquisition (5 hours before bed), while the other was asked to drink the same dose of ethanol just prior to bedtime. Re-testing was done 8 days later at the same time of day. PARTICIPANTS: Subjects in Experiment 1 were 15 college students between the ages of 19 and 24 that appeared to be in good health and were relatively naive in terms of drinking alcohol. Subjects in Experiment 2 were 13 college students in the same age range. These subjects were considered to be more experienced drinkers than subjects in Experiment 1 but were not judged to be heavy drinkers. MEASUREMENTS AND RESULTS: In Experiment 1, the alcohol ingestion resulted in memory loss for the cognitive procedural task but not the declarative task. Further, the effect was seen when alcohol ingestion occurred the same day or 2 days after the end of acquisition. In Experiment 2, alcohol ingestion at bedtime impaired memory for the cognitive procedural and motor procedural tasks. By contrast, alcohol ingestion in the afternoon, immediately after the acquisition of these two tasks, did not impair memory. There were clear changes in the nature of rapid eye movement (REM) sleep as a result of evening alcohol ingestion. In Experiment 1, the number of REMs and number of minutes of REM in the first half of the night were reduced. In Experiment 2, the reduction was in REM densities in the first half of the night. CONCLUSIONS: Moderate doses of ethanol can modify the REM sleep architecture by reducing the number of REMs and/or REM densities as well as minutes of REM sleep, particularly in the first half of the night. These modifications result in memory impairment for recently learned cognitive procedural material. Alcohol may also have a subtle effect on Stage 2 sleep as well, since memory for a Stage 2 sensitive motor procedural task was also impaired.
Administration, Oral↗
Toxocara canis: egg presence in Melbourne parks and disease incidence in Victoria.
PURPOSE: Toxocara canis can cause blinding eye disease. This study assessed the presence of T. canis eggs in soil from parks in Melbourne and also the incidence of presumed ocular toxocariasis in Victoria. METHODS: One hundred and eighty soil samples were collected from nine suburban locations in Melbourne, Australia. These were analyzed for the presence of T. canis eggs. A search of laboratory records of T. canis serology requests from Victorian patients over an 8-year period was performed. RESULTS: Only one soil sample was positive for T. canis eggs. Positive T. canis serology was reported in 13 samples from patients. These patients all had ocular features suggestive of T. canis infection. CONCLUSION: Toxocara canis eggs are rare in public parks in Melbourne and symptomatic ocular toxocariasis is uncommon in the Victorian population. The acquisition of the disease is unlikely to be from public parks.
Adolescent↗
Lake eutrophication at the urban fringe, Seattle region, USA.
Nutrient pollution and associated eutrophication of freshwaters threaten the ecological integrity and the services provided to humans by lakes. We examined how human residential development influenced the level of lake eutrophication in the Seattle, WA, USA, region. We surveyed 30 lakes and measured 3 indicators of eutrophication: concentrations of chlorophyll-a and phosphorus, and the proportion of algae that are inedible to zooplankton. We classified lakes based on the waste-treatment method for shoreline homes: septic, sewer, and undeveloped lakes. Septic lakes occurred along the urban-rural fringe while sewer lakes occurred near urban centers. Septic lakes were more eutrophic than sewer lakes and undeveloped lakes, as indicated by higher levels of phosphorus and chlorophyll-a. These results suggest that septic systems contribute to the high levels of eutrophication in lakes at the urban-rural fringe. Lakes at the urban-rural fringe represent an opportunity for proactive management of urban expansion to minimize lake eutrophication.
Chlorophyll↗
An investigation into the accuracy of different types of thermometers.
The traditional mercury-in-glass thermometer carries the potential risk of glass breakage and mercury spillage and health-care professionals have sought an alternative. This study examined the accuracy of three other types of temperature-measurement device--disposable, digital and tympanic--when compared with standard mercury thermometer readings.
Adolescent↗