Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Parents’ perceptions of an intervention for infants with behavioral sleep problems

Between 13% and 35% of infants and young children have experienced behavioural sleep problems. A pilot study, which was entitled: Evaluation of an Intervention Aimed at Resolving Behavioural Sleep Problems in 6-lo-12-month-old Infants: A Pilot Study, was undertaken to evaluate the efficacy of an intervention. My study comprised the qualitative component of the pilot study. The purpose of my study was to explore parents' perceptions about the sleep intervention used in the pilot study and any burden associated with the study. The sleep intervention included: providing parents information about normal infant sleep, controlled comforting, bedtime routines, organized daytime schedules and naps, and completing forms to record routines and controlled comforting. Following a teaching session about the study intervention, each family implemented the intervention which also included bi-weekly follow-up phone calls to offer support. I used a descriptive, exploratory research design. Through purposive sampling, I identified and interviewed 14 families who had completed the intervention. I used inductive content analysis method to analyze the data. Nine themes emerged from my analysis: changes in perspectives about sleep, gaining a framework to tackle sleep problems, unanticipated changes resulting from using the strategies in the study, challenges for parents, fitting intervention strategies into parents' realities, factors interfering with successful interventions, parents' support systems, parents' expectations of the study, and inadvertent benefits of the study. Each theme subsumed a number of sub-themes. The thesis includes implications of these findings for nursing education, practice, and research.Applied Science, Faculty ofNursing, School ofGraduat

High-throughput physical phenotyping of cell differentiation.

In this report, we present multiparameter deformability cytometry (m-DC), in which we explore a large set of parameters describing the physical phenotypes of pluripotent cells and their derivatives. m-DC utilizes microfluidic inertial focusing and hydrodynamic stretching of single cells in conjunction with high-speed video recording to realize high-throughput characterization of over 20 different cell motion and morphology-derived parameters. Parameters extracted from videos include size, deformability, deformation kinetics, and morphology. We train support vector machines that provide evidence that these additional physical measurements improve classification of induced pluripotent stem cells, mesenchymal stem cells, neural stem cells, and their derivatives compared to size and deformability alone. In addition, we utilize visual interactive stochastic neighbor embedding to visually map the high-dimensional physical phenotypic spaces occupied by these stem cells and their progeny and the pathways traversed during differentiation. This report demonstrates the potential of m-DC for improving understanding of physical differences that arise as cells differentiate and identifying cell subpopulations in a label-free manner. Ultimately, such approaches could broaden our understanding of subtle changes in cell phenotypes and their roles in human biology

Very high vitamin D supplementation rates among infants aged 2 months in Vancouver and Richmond, British Columbia, Canada

Background: Vitamin D deficiency during infancy may lead to rickets and possibly other poor health outcomes. The World Health Organization recommends exclusive breastfeeding for the first 6 months. Breast milk is the best food for infants but does not contain adequate vitamin D. Health Canada recommends all breastfed infants receive a daily vitamin D supplement of 400 IU; however, there appears to be limited current Canadian data as to whether parents or caregivers are following this advice. The aim of this study was to determine the rates of vitamin D supplementation among 2-month old infants in Vancouver and Richmond, British Columbia, Canada. Methods Mothers of all healthy infants born between April and May 2010 were approached to participate. Telephone surveys were conducted with 577 mothers (response rate 56%) when their infants turned 2 months. Results Over half of the infants received only breast milk in the week prior to the survey. One third received a mixture of breast milk and infant formula and 10% received only formula. About 80% of the infants were supplemented with vitamin D at 2 months. Infants who received only breast milk were most likely to be supplemented with vitamin D (91%). Over 60% of the infants had a total vitamin D intake of 300- < 500 IU/d from supplements and formula and only 5% did not receive any vitamin D. Most parents were advised to give vitamin D supplement by health professionals, such as public health nurses, midwives, and doctors. Conclusions About 90% of the infants received breast milk at 2 months of age. The vitamin D supplementation rate was 80%. Future studies are needed to monitor breastfeeding duration and vitamin D supplementation rates as infants get older.Land and Food Systems, Faculty ofNon UBCReviewedFacult

A randomized controlled trial of an intervention for infants’ behavioral sleep problems

Background: Infant behavioral sleep problems are common, with potential negative consequences. We conducted a randomized controlled trial to assess effects of a sleep intervention comprising a two-hour group teaching session and four support calls over 2 weeks. Our primary outcomes were reduced numbers of nightly wakes or parent report of sleep problem severity. Secondary outcomes included improvement in parental depression, fatigue, sleep, and parent cognitions about infant sleep. Methods: Two hundred thirty five families of six-to-eight month-old infants were randomly allocated to intervention (n = 117) or to control teaching sessions (n = 118) where parents received instruction on infant safety. Outcome measures were observed at baseline and at 6 weeks post intervention. Nightly observation was based on actigraphy and sleep diaries over six days. Secondary outcomes were derived from the Multidimensional Assessment of Fatigue Scale, Center for Epidemiologic Studies Depression Measure, Pittsburgh Sleep Quality Index, and Maternal (parental) Cognitions about Infant Sleep Questionnaire. Results: One hundred eight intervention and 107 control families provided six-week follow-up information with complete actigraphy data for 96 in each group: 96.9 % of intervention and 97.9 % of control infants had an average of 2 or more nightly wakes, a risk difference of −0.2 % (95 % CI: −1.32, 0.91). 4 % of intervention and 14 % of control infants had parent-assessed severe sleep problems: relative risk 0.3, a risk difference of −10 % (CI: 0.11, 0.84-16.8 to −2.2). Relative to controls, intervention parents reported improved baseline-adjusted parental depression (CI: −3.7 to −0.4), fatigue (CI: −5.74 to −1.68), sleep quality (CI: −1.5 to −0.2), and sleep cognitions: doubts (CI: −2.0 to −0.6), feeding (CI: − 2.1 to - 0.7), anger (CI: − 1.8 to - 0.4) and setting limits (CI: −3.5 to −1.5). Conclusions: The intervention improved caregivers' assessments of infant sleep problem severity and parental depression, fatigue, sleep, and sleep cognitions compared with controls. Trial registration ISRCTN42169337 , NCT00877162Applied Science, Faculty ofMedicine, Faculty ofScience, Faculty ofOther UBCNon UBCNursing, School ofStatistics, Department ofReviewedFacult