Type IV collagen drives alveolar epithelial-endothelial association and the morphogenetic movements of septation

Background: Type IV collagen is the main component of the basement membrane that gives strength to the blood-gas barrier (BGB). In mammals, the formation of a mature BGB occurs primarily after birth during alveologenesis and requires the formation of septa from the walls of the saccule. In contrast, in avians, the formation of the BGB occurs rapidly and prior to hatching. Mutation in basement membrane components results in an abnormal alveolar phenotype; however, the specific role of type IV collagen in regulating alveologenesis remains unknown. Results: We have performed a microarray expression analysis in late chick lung development and found that COL4A1 and COL4A2 were among the most significantly upregulated genes during the formation of the avian BGB. Using mouse models, we discovered that mutations in murine Col4a1 and Col4a2 genes affected the balance between lung epithelial progenitors and differentiated cells. Mutations in Col4a1 derived from the vascular component were sufficient to cause defects in vascular development and the BGB. We also show that Col4a1 and Col4a2 mutants displayed disrupted myofibroblast proliferation, differentiation and migration. Lastly, we revealed that addition of type IV collagen protein induced myofibroblast proliferation and migration in monolayer culture and increased the formation of mesenchymal-epithelial septal-like structures in co-culture. Conclusions: Our study showed that type IV collagen and, therefore the basement membrane, play fundamental roles in coordinating alveolar morphogenesis. In addition to its role in the formation of epithelium and vasculature, type IV collagen appears to be key for alveolar myofibroblast development by inducing their proliferation, differentiation and migration throughout the developing septum

Aerosol Lidar observations and model calculations of the Planetary Boundary Layer evolution over Greece, during the March 2006 Total Solar Eclipse

International audienceAn investigation of the Planetary Boundary Layer (PBL) height evolution over Greece, during the solar eclipse of 29 March 2006, is presented. Ground based observations were carried out using lidar detection and ranging devices and ground meteorological instruments, to estimate the height of the mixing layer (ML) before, during and after the solar eclipse in northern and southern parts of Greece exhibiting different sun obscuration. Data demonstrate that the solar eclipse has induced a decrease of the PBL height, indicating a suppression of turbulence activity similar to that during the sunset hours. The changes in PBL height were associated with a very shallow entrainment zone, indicating a significant weakening of the penetrative convection. Heat transfer was confined to a thinner layer above the ground. The thickness of the entrainment zone exhibited its minimum during the maximum of the eclipse, demonstrative of turbulence mechanisms suppression at that time. Model estimations of the PBL evolution were additionally conducted using the Comprehensive Air Quality Model with extensions (CAMx) coupled with the Weather Research and Forecasting model (WRF). Model-diagnosed PBL height decrease during the solar eclipse due to vertical transport decay, in agreement with the experimental findings; vertical profiles of atmospheric particles and gaseous species showed an important vertical mixing attenuation

Use and Appreciation of a Web-Based, Tailored Intervention (E-health4Uth) Combined With Counseling to Promote Adolescents’ Health in Preventive Youth Health Care: Survey and Log-File Analysis

BACKGROUND: Health promotion for adolescents is important in the prevention of mental health problems and health-risk behaviors. We implemented two interventions in a preventive youth health care setting. Adolescents in the E-health4Uth group received Web-based, tailored messages on their health behavior and well-being. Adolescents in the E-health4Uth and counseling group received the same tailored messages, but were subsequently referred to a school nurse for a consultation if they were at risk of mental health problems. OBJECTIVE: This study evaluated the use and appreciation of these Web-based, tailored messages and additional consultation with a school nurse. Differences in use and appreciation according to demographics (ie, gender, level of education, and ethnicity) of the adolescents were also assessed. METHODS: Two youth health care organizations participated in this study and conducted the interventions in 12 secondary schools. In total, 1702 adolescents participated; 533 in the E-health4Uth group, 554 in the E-health4Uth and counseling group, and 615 in the control group (ie, care as usual). Adolescents completed an evaluation questionnaire assessing the use and appreciation of the tailored messages immediately after receiving these messages and at a 4-month follow-up. After the consultation, adolescents and nurses completed an evaluation questionnaire on the use and appreciation of the consultation. RESULTS: The majority of the adolescents (845/1034, 81.72%) indicated they had read the tailored messages. Most items on the use and appreciation of the tailored messages and the program were scored positive (overall satisfaction on a scale from 1, most-negative, to 10, most-positive: mean 6.70, SD 1.60). In general, adolescents in vocational training, girls, and adolescents of non-Dutch ethnicity, indicated they used the tailored messages more often and appreciated the content of the messages better than adolescents receiving preuniversity education, boys, and adolescents of Dutch ethnicity, respectively (all P<.05). In the E-health4Uth and counseling group, 18.6% (103/553) of the adolescents were referred to a nurse. Adolescents in vocational training and girls were more often referred to a nurse than adolescents receiving preuniversity education (P=.007) and boys (P=.03), respectively. Adolescents and nurses positively evaluated the consultation (overall satisfaction of adolescents: mean 8.07, SD 1.21). Adolescents in vocational training attended the consultation more often (P=.047) and considered the consultation a more valuable addition to the tailored messages than adolescents receiving preuniversity education (P=.034). CONCLUSIONS: The Web-based, tailored messages and additional consultation were used and appreciated positively by adolescents and nurses. The consultation seems a valuable addition to the tailored messages. However, the tailored messages might need further improvement since adolescents did not rate all evaluation items about these messages explicitly positive. As these interventions were already interweaved with the existing practice of the preventive youth health care, they are especially promising for future implementation. TRIAL REGISTRATION: Netherlands Trial Register Number (NTR): NTR3596; http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=3596 (Archived by WebCite at http://www.webcitation.org/6LryL42zH)