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Objective: Hygienic hand disinfection is of major importance regarding nosocomial infections and antibiotic resistance. The six-step technique is the most commonly taught method, but its superiority has not been empirically demonstrated. This study compares two hand disinfection techniques with regard to their total distribution of the disinfectant.
Methods: In this comparative effectiveness analysis, medical students were randomized into two groups. Group 1 was instructed in the 6-step technique, group 2 was referred to a self-responsible application. Learning success was measured using fluorescent disinfectant and black light photographs at three time points (directly, few days later, 5–12 weeks later). Photographs were evaluated quantitatively.
Results: 198 students were included in the study (Group 1: 6-step technique; n=103, Group 2: self-responsible disinfection; n=95). 186 were followed up at the second measurement, 182 at the third measurement. Directly after training, there were no significant differences between the two groups. At the second measurement, Group 2 outperformed Group 1 for total, dorsal, and palmar areas (p<0.001, p=0.002, p<0.001). At the third measurement, Group 2 was significantly better (p=0.019) for palmar-sided hands.
In Group 1, areas of disinfected skin deteriorated significantly between measurement 1 and 2 (p=0.019) and measurement 2 and 3 (p<0.001). Group 2 did not deteriorate between measurement 1 and 2 (p=0.269) but between measurement 2 and 3 (p<0.001).
Conclusions: Compared to the established six-step technique, a self-responsible application method results in measurably better distribution of the hand disinfectant.
Cephalization is a major innovation of animal evolution and implies a synchronization of nervous system, mouth, and foregut polarization to align alimentary tract and sensomotoric system for effective foraging. However, the underlying integration of morphogenetic programs is poorly understood. Here, we show that invagination of neuroectoderm through de novo polarization and apical constriction creates the mouth opening in the Caenorhabditis elegans embryo. Simultaneously, all 18 juxta-oral sensory organ dendritic tips become symmetrically positioned around the mouth: While the two bilaterally symmetric amphid sensilla endings are towed to the mouth opening, labial and cephalic sensilla become positioned independently. Dendrite towing is enabled by the pre-polarized sensory amphid pores intercalating into the leading edge of the anteriorly migrating epidermal sheet, while apical constriction-mediated cell–cell re-arrangements mediate positioning of all other sensory organs. These two processes can be separated by gradual inactivation of the 26S proteasome activator, RPN-6.1. Moreover, RPN- 6.1 also shows a dose-dependent requirement for maintenance of coordinated apical polarization of other organs with apical lumen, the pharynx, and the intestine. Thus, our data unveil integration of morphogenetic programs during the coordination of alimentary tract and sensory organ formation and suggest that this process requires tight control of ubiquitin-dependent protein degradation.
Selfish genetic elements that act as post-segregation distorters cause lethality in non-carrier individuals after fertilization. Two post-segregation distorters have been previously identified in Caenorhabditis elegans, the peel-1/zeel-1 and the sup-35/pha-1 elements. These elements seem to act as modification-rescue systems, also called toxin/antidote pairs. Here we show that the maternal-effect toxin/zygotic antidote pair sup-35/pha-1 is required for proper expression of apical junction (AJ) components in epithelia and that sup-35 toxicity increases when pathways that establish and maintain basal epithelial characteristics, die-1, elt-1, lin-26, and vab-10, are compromised. We demonstrate that pha-1(e2123) embryos, which lack the antidote, are defective in epidermal morphogenesis and frequently fail to elongate. Moreover, seam cells are frequently misshaped and mispositioned and cell bond tension is reduced in pha-1(e2123) embryos, suggesting altered tissue material properties in the epidermis. Several aspects of this phenotype can also be induced in wild-type embryos by exerting mechanical stress through uniaxial loading. Seam cell shape, tissue mechanics, and elongation can be restored in pha-1(e2123) embryos if expression of the AJ molecule DLG-1/Discs large is reduced. Thus, our experiments suggest that maternal-effect toxicity disrupts proper development of the epidermis which involves distinct transcriptional regulators and AJ components.
