Influence of indoor airflow on particle spread of a single breath and cough in enclosures: Does opening a window really 'help'?

The spread of respiratory diseases via aerosol particles in indoor settings is of significant concern. The SARS-CoV-2 virus has been found to spread widely in confined enclosures like hotels, hospitals, cruise ships, prisons, and churches. Particles exhaled from a person indoors can remain suspended long enough for increasing the opportunity for particles to spread spatially. Careful consideration of the ventilation system is essential to minimise the spread of particles containing infectious pathogens. Previous studies have shown that indoor airflow induced by opened windows would minimise the spread of particles. However, how outdoor airflow through an open window influences the indoor airflow has not been considered. The aim of this study is to provide a clear understanding of the indoor particle spread across multiple rooms, in a situation similar to what is found in quarantine hotels and cruise ships, using a combination of HVAC (Heating, Ventilation and Air-Conditioning) ventilation and an opening window. Using a previously validated mathematical model, we used 3D CFD (computational fluid dynamics) simulations to investigate to what extent different indoor airflow scenarios contribute to the transport of a single injection of particles ( 1 . 3 µ m ) in a basic 3D multi-room indoor environment. Although this study is limited to short times, we demonstrate that in certain conditions approximately 80% of the particles move from one room to the corridor and over 60% move to the nearby room within 5 to 15 s. Our results provide additional information to help identifying relevant recommendations to limit particles from spreading in enclosures.

Heat shocks enhance procollagen type I and III expression in fibroblasts in ex vivo human skin.

BACKGROUND: The well-known characteristics of aging skin are the development of fine lines and wrinkles, but changes in skin tone, skin texture, thickness and moisture content are also aspects of aging. Rejuvenation of the skin aims at reversing the signs of aging and can be established in the epidermis as well as in the dermis. Aged dermis, in fact, has a degenerated collagen matrix. To regenerate this matrix, fibroblasts need to be stimulated into synthesizing new collagen. AIMS: In this study, the effects of heat shocks of different temperatures on human dermal fibroblasts in ex vivo skin on the expression of procollagen 1, procollagen 3, heat shock protein (hsp)27, hsp47, and hsp70 are investigated. MATERIALS AND METHODS: The heat shocks were applied on ex vivo skin samples by immersing the samples in heated phosphate-buffered saline of 45 °C or 60 °C. Metabolic activity was measured and at similar time points propidium-iodide-calceine staining was performed to establish cell viability. Quantitative polymerase chain reaction (qPCR) was performed after the heat shock to determine gene expression levels relative to the reference temperature. Furthermore, PicroSirius Red and hematoxylin stainings were performed to visualize the collagen network and the cells. RESULTS: The skin samples were shown to be viable and metabolically active. Histology indicated that the heat shocks did not influence the structure of the collagen network or cell appearance. qPCR results showed that in contrast to the 45 °C heat shock the 60 °C heat shock resulted in significant upregulations of procollagen type I and III, hsp70 and hsp47. CONCLUSION: A 60 °C, heat shock stimulates the human dermal fibroblasts in ex vivo skin to upregulate their procollagen type I and type III expression.

Pulsed heat shocks enhance procollagen type I and procollagen type III expression in human dermal fibroblasts.

BACKGROUND: The formation of wrinkles is associated with degeneration of the collagen matrix. For regeneration of the matrix, fibroblasts need to be stimulated in producing new collagen. AIMS: In this study, the effect of short-pulsed heat shocks on gene expression of procollagen type I, procollagen type III, heat shock protein (hsp)27, hsp47 and hsp70 and on the expression of remodeling markers, procollagen type I carboxy-terminal peptide (P1P) and carboxy-terminal telopeptide of type I (ICTP), of human dermal fibroblasts in vitro, is investigated. MATERIALS AND METHODS: Temperatures of 45 degrees C and 60 degrees C were used for the heat shocks. The proliferation rates, viability and metabolic activity were measured directly after the pulsed heat shocks and quantitative PCR was performed at five different time points after the heat shocks. Enzyme Immuno Assays were performed to determine the concentrations of P1P and ICTP. RESULTS: A decreased proliferation rate of the 60 degrees C heat shocked cells was shown, whereas the viability and metabolic activity did not differ. Furthermore, gene expressions were upregulated in both 45 degrees C and 60 degrees C heat-shocked cells. However, remodeling marker analyses showed a larger amount of collagen produced by 60 degrees C heat-shocked cells. CONCLUSION: It can be concluded that these findings, together with upregulation in gene expression, show that it is possible to stimulate the cells to produce more collagen with short-pulsed heat shocks.

Interplay between VHL/HIF1alpha and Wnt/beta-catenin pathways during colorectal tumorigenesis.

Activation of the Wnt signaling pathway initiates the transformation of colorectal epithelial cells, although the transition to metastatic cancer requires angiogenesis. We have investigated the expression of the von Hippel-Lindau (VHL) tumor suppressor in the intestines from humans and mice. Here, we show that VHL expression is regulated by TCF4 and is restricted to the proliferative compartment at the bottom of intestinal crypts. Accordingly, VHL is completely absent from the proliferative intestinal pockets of Tcf4(-/-) perinatal mice. We observed complementary staining of the hypoxia-inducible factor (HIF) 1alpha to VHL in normal intestinal epithelium as well as in all stages of colorectal cancer (CRC). To the best of our knowledge, this is the first report demonstrating the presence of nuclear HIF1alpha in normoxic healthy adult tissue. Although we observed upregulated levels of VHL in very early CRC lesions from sporadic and familial adenomatous polyposis patients - presumably due to activated Wnt signaling - a clear reduction of VHL expression is observed in later stages of CRC progression, coinciding with stabilization of HIF1alpha. As loss of VHL in later stages of CRC progression results in stabilization of HIF, these data provide evidence that selection for VHL downregulation provides a proangiogenic impulse for CRC progression.

Active and intelligent packaging: applications and regulatory aspects.

Changes in the way foods are produced, distributed, stored and retailed, reflecting the continuing increase in consumer demands for improved quality and extended shelf-life for packaged foods, are placing ever-greater demands on the performance of food packaging. Consumers want to be assured that the packaging is fulfilling its function of protecting the integrity, quality, freshness and safety of foods. To provide this assurance and help improve the performance of the packaging, innovative active and intelligent packaging concepts are being developed and applied in various countries. In Europe, however, the development and application of active and intelligent packaging systems have been limited thus far. The main reasons are legislative restrictions and a lack of knowledge about consumer acceptance, the efficacy of such systems, and the economic and environmental impact they may have. Therefore, in 1999, a European study was started within the framework of the EU FAIR R&D programme. It aims to initiate amendments to European legislation for food-contact materials to establish and implement active and intelligent systems within the current relevant regulations for packaged food in Europe. This paper presents an overview of existing active and intelligent systems and their current and future food-related applications. In addition, developments and trends in active and intelligent food packaging are discussed. The objectives and the work programme of the European project are reviewed and the results obtained so far are presented. The benefits for both the European consumer and the European food and food-packaging industries are highlighted.

decapentaplegic is a direct target of dTcf repression in the Drosophila visceral mesoderm.

Drosophila T cell factor (dTcf) mediates transcriptional activation in the presence of Wingless signalling and repression in its absence. Wingless signalling is required for the correct expression of decapentaplegic (dpp), a Transforming Growth Factor (beta) family member, in parasegments 3 and 7 of the Drosophila visceral mesoderm. Here we demonstrate that a dpp enhancer element, which directs expression of a reporter gene in the visceral mesoderm in a pattern indistinguishable from dpp, has two functional dTcf binding sites. Mutations that reduce or eliminate Wingless signalling abolish dpp reporter gene expression in parasegment 3 and reduce it in parasegment 7 while ectopic expression of Wingless signalling components expand reporter gene expression anteriorly in the visceral mesoderm. However, mutation of the dTcf binding sites in the dpp enhancer results in ectopic expression of reporter gene expression throughout the visceral mesoderm, with no diminution of expression in the endogenous sites of expression. These results demonstrate that the primary function of dTcf binding to the dpp enhancer is repression throughout the visceral mesoderm and that activation by Wingless signalling is probably not mediated via these dTcf binding sites to facilitate correct dpp expression in the visceral mesoderm.

Sequence-specific high mobility group box factors recognize 10-12-base pair minor groove motifs.

Sequence-specific high mobility group (HMG) box factors bind and bend DNA via interactions in the minor groove. Three-dimensional NMR analyses have provided the structural basis for this interaction. The cognate HMG domain DNA motif is generally believed to span 6-8 bases. However, alignment of promoter elements controlled by the yeast genes ste11 and Rox1 has indicated strict conservation of a larger DNA motif. By site selection, we identify a highly specific 12-base pair motif for Ste11, AGAACAAAGAAA. Similarly, we show that Tcf1, MatMc, and Sox4 bind unique, highly specific DNA motifs of 12, 12, and 10 base pairs, respectively. Footprinting with a deletion mutant of Ste11 reveals a novel interaction between the 3' base pairs of the extended DNA motif and amino acids C-terminal to the HMG domain. The sequence-specific interaction of Ste11 with these 3' base pairs contributes significantly to binding and bending of the DNA motif.

Activation of pre- and postsynaptic protein kinase C during tetraethylammonium-induced long-term potentiation in the CA1 field of the hippocampus.

Tetraethylammonium (TEA) induces a form of long-term potentiation (LTP) that is independent on N-methyl-D-aspartate (NMDA) receptor activation (LTP(K)). LTP(K) may be a suitable chemical model to study molecular mechanisms underlying LTP. We monitored the phosphorylation state of two identified neural-specific protein kinase C (PKC) substrates (the presynaptic protein GAP-43/B-50 and postsynaptic protein RC3) after different chemical depolarisations. TEA induced a long-lasting increase in synaptic efficacy in the CA1 field of the hippocampus and increased the phosphorylation of both GAP-43/B-50 and RC3 (51 and 56.1%, respectively). These effects were blocked by the voltage-dependent calcium channel antagonist nifedipine, but not by the NMDA receptor antagonist AP5. These data show that in LTP(K) the in situ phosphorylation of pre-and postsynaptic PKC substrates is increased, indicating that NMDA receptor-dependent and NMDA receptor-independent LTP share common Ca(2+)-dependent expression mechanisms, including activation of pre- and postsynaptic PKC.

Synergy between tumor suppressor APC and the beta-catenin-Tcf4 target Tcf1.

Mutations in APC or beta-catenin inappropriately activate the transcription factor Tcf4, thereby transforming intestinal epithelial cells. Here it is shown that one of the target genes of Tcf4 in epithelial cells is Tcf1. The most abundant Tcf1 isoforms lack a beta-catenin interaction domain. Tcf1(-/-) mice develop adenomas in the gut and mammary glands. Introduction of a mutant APC allele into these mice substantially increases the number of these adenomas. Tcf1 may act as a feedback repressor of beta-catenin-Tcf4 target genes and thus may cooperate with APC to suppress malignant transformation of epithelial cells.

The relationship between adolescents' social support from parents and from peers.

This study investigated the relationship between adolescents' social support from parents and from peers. Three hypotheses were tested. The first hypothesis was that adolescents who experience little parental support will compensate with support from peers. A negative correlation would thus be expected between perception of parental support on the one hand, and support from peers on the other. The second hypothesis was that lack of parental support will not be compensated by peer support, because such compensation is impossible. Thus, there would be no correlation. The third hypothesis was that adolescents in these circumstances lack the opportunity or ability to gain social support from anyone, including peers. A positive correlation would therefore be expected. These hypotheses were tested in a sample of 1,528 urban Dutch secondary school students (aged 14-16 years) who were in the third year of an intermediate educational stream. Analysis indicated that Hypothesis 1 was not substantiated. The results also argued against Hypothesis 3 and in favor of Hypothesis 2.

Drosophila RpS3a, a novel Minute gene situated between the segment polarity genescubitus interruptus and dTCF.

Genetic analysis of the small chromosome 4 of Drosophila has been hampered by the virtual lack of recombination. The segment polarity gene cubitus interruptus (ci) maps to the most intensively studied locus on this chromosome. Up to four complementation groups have been found to be associated with ci. We and others have recently characterized a second segment polarity gene, dTCF or pan, 12 kb upstream of ci, in a head-to-head configuration. During the course of these studies we identified a transcription unit in the intergenic region. We report here the cloning of cDNAs from this transcription unit, which encode the Drosophila homologue of the human ribosomal protein S3a (RpS3a). The RpS3a gene is expressed ubiquitously and throughout development. A Minute allele, M(4)101, linked tightly to ci, was found to harbour an integration of a Doc retroposon in the promotor region of RpS3a. Thus, like other Minute loci, M(4)101 encodes a component of the protein synthesis machinery. These data further unravel the complex genetics surrounding the ci and dTCF loci.

Genomic organization of the segment polarity gene pan in Drosophila melanogaster.

We previously described the molecular cloning of a mammalian T cell factor 1 (TCF-1)-like protein from Drosophila melanogaster, encoded by the pangolin (pan) locus, and demonstrated that it consists of a DNA binding domain similar to that of other high mobility group proteins and a protein-protein interaction domain that binds beta-catenin (Armadillo in Drosophila) but that it lacks a transcriptional activation domain. Here we show that the pan locus spans approximately 50 kb and the mRNA results from the splicing of 13 exons. We note remarkable conservation of the exon/intron boundaries between the human and D. melanogaster genes, suggesting that they share a common ancestor. Chromosomal in situ hybridization locates pan to the base of chromosome 4, near the cubitus interruptus locus. Restriction map and sequence analyses confirm their close proximity. The small fourth chromosome undergoes little or no recombination and was previously reported to lack DNA polymorphisms; however, we note two DNA polymorphisms occurring in three combinations within the pan locus, demonstrating the presence of synonymous substitutions and the past occurrence of recombination. We present evidence suggesting that the protein encoded by pan is more similar to mammalian TCF-1 and Caenorhabditis elegans POP-1 than to mammalian LEF-1.

Armadillo coactivates transcription driven by the product of the Drosophila segment polarity gene dTCF.

The vertebrate transcription factors TCF (T cell factor) and LEF (lymphocyte enhancer binding factor) interact with beta-catenin and are hypothesized to mediate Wingless/Wnt signaling. We have cloned a maternally expressed Drosophila TCF family member, dTCF. dTCF binds a canonical TCF DNA motif and interacts with the beta-catenin homolog Armadillo. Previous studies have identified two regions in Armadillo required for Wingless signaling. One of these interacts with dTCF, while the other constitutes a transactivation domain. Mutations in dTCF and expression of a dominant-negative dTCF transgene cause a segment polarity phenotype and affect expression of the Wingless target genes engrailed and Ultrabithorax. Epistasis analysis positions dTCF downstream of armadillo. The Armadillo-dTCF complex mediates Wingless signaling as a bipartite transcription factor.