Biofilm‐Eradicating Properties of Quaternary Ammonium Amphiphiles: Simple Mimics of Antimicrobial Peptides

Bacterial biofilms are difficult to eradicate because of reduced antibiotic sensitivity and altered metabolic processes; thus, the development of new approaches to biofilm eradication is urgently needed. Antimicrobial peptides (AMPs) and quaternary ammonium cations (QACs) are distinct, yet well‐known, classes of antibacterial compounds. By mapping the general regions of charge and hydrophobicity of QACs onto AMP structures, we designed a small library of QACs to serve as simple AMP mimics. In order to explore the role that cationic charge plays in biofilm eradication, structures were varied with respect to cationic character, distribution of charge, and alkyl side chain. The reported compounds possess minimum biofilm eradication concentrations (MBEC) as low as 25 μM against Gram‐positive biofilms, making them the most active anti‐biofilm structures reported to date. These potent AMP mimics were synthesized in 1–2 steps and hint at the minimal structural requirements for biofilm destruction.     

Calibration of multiplexed fiber-optic spectroscopy

Large-scale commercial bioprocesses that manufacture biopharmaceutical products such as monoclonal antibodies generally involve multiple bioreactors operated in parallel. Spectra recorded during in situ monitoring of multiple bioreactors by multiplexed fiber-optic spectroscopies contain not only spectral information of the chemical constituents but also contributions resulting from differences in the optical properties of the probes. Spectra with variations induced by probe differences cannot be efficiently modeled by the commonly used multivariate linear calibration models or effectively removed by popular empirical preprocessing methods. In this study, for the first time, a calibration model is proposed for the analysis of complex spectral data sets arising from multiplexed probes. In the proposed calibration model, the spectral variations introduced by probe differences are explicitly modeled by introducing a multiplicative parameter for each optical probe, and then their detrimental effects are effectively mitigated through a "dual calibration" strategy. The performance of the proposed multiplex calibration model has been tested on two multiplexed spectral data sets (i.e., MIR data of ternary mixtures and NIR data of bioprocesses). Experimental results suggest that the proposed calibration model can effectively mitigate the detrimental effects of probe differences and hence provide much more accurate predictions than commonly used multivariate linear calibration models (such as PLS) with and without empirical data preprocessing methods such as orthogonal signal correction, standard normal variate, or multiplicative signal correction.     

Coating effects on mid-infrared reflection spectra of fabrics

Polymer films of varying thicknesses were deposited onto cotton and polyester fabric samples by dip-coating from solution. Scanning electron microscopy (SEM) images of the coated fabric samples were used to evaluate the quality of the polymer coating. The samples were analyzed by infrared diffuse reflection spectroscopy to determine the relationship between film thickness and the effect of the coating on the spectroscopy of the two fabrics. Effects observed in four limiting cases are examined: (Case I) weak coating absorption on a fabric with weak absorption at the same frequency; (Case II) strong coating absorption in a spectral region of weak fabric absorption; (Case III) weak coating absorption in a spectral region of strong fabric absorption; and (Case IV) strong coating absorption in a spectral region of strong fabric absorption. In the first case, effects were dominated by reduced scattering as the coating is added. In the second case, the strong coating absorption that was observed at low coverages plateaus at higher coverage due to depth of penetration effects. In the third and fourth cases, reduced Fresnel diffuse reflection is measured as the coating is added, consistent with the reduction of scattering observed in the first case.     

Sibling conflict in middle childhood predicts children's adjustment in early adolescence.

Associations between sibling conflict in middle childhood and psychological adjustment in early adolescence were studied in a sample of 80 boys and 56 girls. Parents and children provided self-report data about family relationships and children's adjustment. Parents' hostility to children was assessed from videotaped interactions. Results showed that sibling conflict at Time 1 predicted increases in children's anxiety, depressed mood, and delinquent behavior 2 years later. Moreover, earlier sibling conflict at Time 1 accounted for unique variance in young adolescents' Time 2 anxiety, depressed mood, and delinquent behavior above and beyond the variance explained by earlier maternal hostility and marital conflict. Children's adjustment at Time 1 did not predict sibling conflict at Time 2. Results highlight the unique significance of the earlier sibling relationship for young adolescents' psychological adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of parents with and without disabilities raising teens: Information from the nhis and two national surveys.

Objectives: To contrast families headed by parents with disabilities raising children ages 11-17 years with families headed by parents without disabilities. Study Design: There were 3 sources of data: (a) the National Health Institute Survey (National Center for Health Statistics, 2000), (b) a previous national survey (L. T. T. Barker & V. Maralani, 1997), (c) a new national survey of parents with disabilities (n = 273) and their teens (ages 11-17 years; n = 246) and a control group of parents without disabilities (n = 48) and their teens (n = 37). Main Measure: Participants completed a survey designed for this study. Results: Parents with disabilities were generally quite similar to parents without disabilities, with some notable differences, particularly in employment and income. Deaf parents exhibited certain differences from parents with other disabilities. Conclusion: Survey responses provided a snapshot of parents with disabilities and their families from community samples, including aspects in which disabled and nondisabled participants were similar. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When are dysphoric individuals distressing to others and vice versa? Effects of friendship, similarity, and interaction task.

Examined several factors hypothesized to affect how dysphoric and nondysphoric individuals react to each other. 92 pairs of female college students participated in the study. Ss interacted with either a friend or stranger who had a similar or dissimilar dysphoria status in 3 tasks: a casual conversation, disclosure of a personal problem to the partner, and response to the partner's disclosure of a personal problem. Ss' moods, evaluations of their partners, and verbal behaviors were assessed. Dysphoric Ss exhibited characteristic negative mood and verbal content but did not elicit negative reactions from their partners. Negative reactions were most evident in dysphoric Ss' responses to dissimilar (nondysphoric) strangers, underscoring the need for greater attention to dysphoric individuals' perspective on their social interactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of single bacterial pathogens with semiconductor quantum dots

Semiconductor quantum dots (QDs) have been used in a simple fluorometric assay to detect single cells of the pathogenic Escherichia coli O157:H7 serotype. Composed of CdSe/ZnS core/shell QDs conjugated to streptavidin, this system exhibits 2 orders of magnitude more sensitivity than a similar assay using a common organic dye. Selectivity for this pathogenic bacterial strain over a common lab strain (E. coli DH5alpha), which is gained from the use of specific biotinylated antibodies, is also demonstrated for QD labeling. Under continuous excitation, these QDs retain high fluorescence intensities for hours, whereas a typical organic dye bleaches within seconds, allowing for more rapid and accurate identification of E. coli O157:H7 in single-cell fluorescence-based assays. This indirect QD labeling method, based on antibody-antigen and streptavidin-biotin interactions, is flexible enough to expand to other systems and has great potential for use in simultaneous multicolor detection schemes.     

Physical demands analysis of occupational tasks in neighborhood pubs

This paper describes a case study of a neighborhood pub in British Columbia, Canada. This case study is an examination of three common pub occupations-bartending, waitressing and cooking (n = 17). The aims of this study are to determine the biomechanical loads of job tasks identified as physically demanding for the three occupations analyzed, to assess the potential risk of musculoskeletal injury in these job tasks, and to recommend injury prevention measures. Risk of musculoskeletal injury was assessed with four validated methods (RULA, NIOSH lifting equation, Shoaf pulling model, 3D Static Strength prediction program). Tasks commonly and frequently performed were observed to pose some risk to the working populations and require investigation and changes soon as indicated by the upper extremity and low-back assessment procedures used. Mean combined compression at the lumbrosacral disc in common tasks have been demonstrated to exceed the action limit described by NIOSH. Ligament strain was observed to reach as high as 18% at the lumbosacral joint.     

Reliability of the Revised Psychopathy Checklist in substance abuse patients.

Examined the 1-mo test–retest reliability of the revised Psychopathy Checklist (PCL—R) in 88 methadone-maintained male patients (average age nearly 40 yrs) as well as the effects of increased information (interview, clinical chart review, partial and complete criminal records) on PCL—R scores and on 2 diagnostic derivations of the PCL—R. PCL—R scores and diagnostic proportions were not found to differ significantly between baseline and 1 mo. However, increased amounts of rater information resulted in significantly higher PCL—R scores and more positive diagnoses. Test–retest reliabilities of PCL—R scores were found to be excellent, and the reliabilities of each of its 2 factors were also quite good. Diagnostic reliabilities were also good, based on the interview alone, but appeared to improve with increasing information available to the rater. The findings suggest that the PCL—R continues to show promise as a research tool. However, because clinical and criminal records may be difficult to obtain for nonprison populations and settings, there may be limitations in the use of the PCL—R to diagnose psychopathy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)