163 research outputs found

    A comparison of snack serving sizes to USDA guidelines in healthy weight and overweight minority preschool children enrolled in Head Start

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    Background Obesity disproportionately affects children from low-income families and those from racial and ethnic minorities. The relationship between snacking and weight status remains unclear, although snacking is known to be an important eating episode for energy and nutrient intake particularly in young children. The purpose of this pilot study was to examine the snack intake of minority preschool children enrolled in the Head Start Program in four centers in Detroit, Michigan, and investigate differences by child weight status. Methods This secondary data analysis used snack time food observation and anthropometric data from a convenience sample of 55 African American children (44æ% girls, mean age?=?3.8æyears). Snack intake data was obtained over a mean of 5 days through direct observation of children by dietetic interns, and later converted into food group servings according to the United States Department of Agriculture (USDA) meal patterns and averaged for each child. Height and weight measurements were systematically collected and BMI-for-age percentiles were used to classify children into weight categories. One sample, paired samples and independent samples t-tests were performed to test for differences within and between means. Results Based on BMI-for-age percentiles, 72.7æ% of the sample was under/healthy weight and 27.3æ% was overweight/obese. Average (mean?±?SD) intake of milk (0.76?±?0.34) and overall fruits/vegetables (0.77?±?0.34) was significantly lower than one USDA serving, while average intake of grains and breads (2.04?±?0.89), meat/meat alternates (2.20?±?1.89) and other foods (1.43?±?1.08) was significantly higher than one USDA serving (p???0.05). Children ate more when offered canned versus fresh fruits (0.93?±?0.57 vs. 0.65?±?0.37, p?=?0.007). Except for a significantly higher milk intake in the overweight/obese group compared to the under/healthy weight group (0.86?±?0.48 vs. 0.72?±?0.27, p?=?0.021], no relationship was found between snack food intake and weight category. Only in the overweight/obese group was the intake of milk and fresh fruits not significantly different than one USDA serving. Conclusions Findings suggest that regardless of weight status low-income minority preschool children are consuming larger serving sizes when offered less healthy versus healthier snack foods. Continued efforts should be made to provide healthful snack foods at preschool settings to prevent obesity and promote healthier food habits

    Antimicrobial polymers : mimicking amino acid functionality, sequence control and three-dimensional structure of host-defense peptides

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    Peptides and proteins control and direct all aspects of cellular function and communication. Having been honed by nature for millions of years, they also typically display an unsurpassed specificity for their biological targets. This underlies the continued focus on peptides as promising drug candidates. However, the development of peptides into viable drugs is hampered by their lack of chemical and pharmacokinetic stability and the cost of large scale production. One method to overcome such hindrances is to develop polymer systems that are able to retain the important structural features of these biologically active peptides, while being cheaper and easier to produce and manipulate chemically. This review illustrates these principles using examples of polymers designed to mimic antimicrobial host-defence peptides. The host-defence peptides have been identified as some of the most important leads for the next generation of antibiotics as they typically exhibit broad spectrum antimicrobial ability, low toxicity toward human cells and little susceptibility to currently known mechanisms of bacterial resistance. Their movement from the bench to clinic is yet to be realised, however, due to the limitations of these peptides as drugs. The literature provides a number of examples of polymers that have been able to mimic these peptides through all levels of structure, starting from specific amino acid sidechains, through to more global features such as overall charge, molecular weight and three-dimensional structure (e.g. α-helical). The resulting optimised polymers are able retain the activity profile of the peptides, but within a synthetic macromolecular construct that may be better suited to the development of a new generation of antimicrobial therapeutics. Such work has not only produced important new leads to combat the growing threat of antibiotic resistance, but may also open up new ways for polymers to mimic other important classes of biologically active peptides

    Disentangling how urbanisation influences moth diversity in grasslands

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    1. Urban areas have profound impacts on local species diversity and composition through a set of intertwined changes in the environment. As the world is rapidly urbanising while simultaneously facing a biodiversity crisis, a better understanding of how urbanisation influences biodiversity is necessary. 2. To test if and how urbanisation influences moth diversity and whether urbanisation is acting directly or indirectly via urbanisation‐induced increased habitat isolation, smaller habitat area, higher light pollution and increased mowing intensity, we sampled moths with light trapping in 20 grasslands in the urban core of the city of Darmstadt (southwestern Germany) and 20 grasslands in the surrounding area. 3. Moth abundance and diversity decreased with increasing urbanisation. Smaller habitat area and high mowing intensity reduced moth abundance, while other environmental variables including isolation and light pollution had only indirect effects. High levels of urbanisation were associated with reduced moth abundance, which in turn drove declines in diversity. Urbanised sites favoured generalist species and differed in species composition compared to sites in the surrounding. 4. The results show that urbanisation is directly reducing moth abundance and diversity in cities. The negative effect of urbanisation is further attenuated by habitat fragmentation and high mowing intensity, which are both known drivers of biodiversity decline in urban areas and beyond. 5. While urbanisation itself is often irreversible, reducing mowing intensity and preserving larger grassland areas could facilitate moths and other taxa in and around cities

    Intramolecular Energy and Electron Transfer Within a Diazaperopyrenium-Based Cyclophane

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    Molecules capable of performing highly efficient energy transfer and ultrafast photo-induced electron transfer in well-defined multichromophoric structures are indispensable to the development of artificial photosynthetic systems. Herein, we report on the synthesis, characterization and photophysical properties of a rationally designed multichromophoric tetracationic cyclophane, DAPPBox^(4+), containing a diazaperopyrenium (DAPP^(2+)) unit and an extended viologen (ExBIPY^(2+)) unit, which are linked together by two p-xylylene bridges. Both ^1H NMR spectroscopy and single crystal X-ray diffraction analysis confirm the formation of an asymmetric, rigid, box-like cyclophane, DAPPBox^(4+). The solid-state superstructure of this cyclophane reveals a herringbone-type packing motif, leading to two types of π···π interactions: (i) between the ExBIPY^(2+) unit and the DAPP^(2+) unit (π···π distance of 3.7 Å) in the adjacent parallel cyclophane, as well as (ii) between the ExBIPY^(2+) unit (π···π distance of 3.2 Å) and phenylene ring in the closest orthogonal cyclophane. Moreover, the solution-phase photophysical properties of this cyclophane have been investigated by both steady-state and time-resolved absorption and emission spectroscopies. Upon photoexcitation of DAPPBox^(4+) at 330 nm, rapid and quantitative intramolecular energy transfer occurs from the ^1*ExBIPY^(2+) unit to the DAPP^(2+) unit in 0.5 ps to yield ^1*DAPP^(2+). The same excitation wavelength simultaneously populates a higher excited state of ^1*DAPP^(2+) which then undergoes ultrafast intramolecular electron transfer from ^1*DAPP^(2+) to ExBIPY^(2+) to yield the DAPP^(3+•) – ExBIPY^(+•) radical ion pair in τ = 1.5 ps. Selective excitation of DAPP^(2+) at 505 nm populates a lower excited state where electron transfer is kinetically unfavorable

    Quantum Mechanical and Experimental Validation that Cyclobis(paraquat-p-phenylene) Forms a 1:1 Inclusion Complex with Tetrathiafulvalene

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    The promiscuous encapsulation of π-electron-rich guests by the π-electron-deficient host, cyclobis(paraquat-p-phenylene) (CBPQT^(4+)), involves the formation of 1:1 inclusion complexes. One of the most intensely investigated charge-transfer (CT) bands, assumed to result from inclusion of a guest molecule inside the cavity of CBPQT^(4+), is an emerald-green band associated with the complexation of tetrathiafulvalene (TTF) and its derivatives. This interpretation was called into question recently in this journal based on theoretical gas-phase calculations that reinterpreted this CT band in terms of an intermolecular side-on interaction of TTF with one of the bipyridinium (BIPY^(2+)) units of CBPQT^(4+), rather than the encapsulation of TTF inside the cavity of CBPQT^(4+). We carried out DFT calculations, including solvation, that reveal conclusively that the CT band emerging upon mixing TTF with CBPQT^(4+) arises from the formation of a 1:1 inclusion complex. In support of this conclusion, we have performed additional experiments on a [2]rotaxane in which a TTF unit, located in the middle of its short dumbbell, is prevented sterically from interacting with either one of the two BIPY^(2+) units of a CBPQT^(4+) ring residing on a separate [2]rotaxane in a side-on fashion. This [2]rotaxane has similar UV/Vis and ^1H NMR spectroscopic properties with those of 1:1 inclusion complexes of TTF and its derivatives with CBPQT^(4+). The [2]rotaxane exists as an equimolar mixture of cis- and trans-isomers associated with the disubstituted TTF unit in its dumbbell component. Solid-state structures were obtained for both isomers, validating the conclusion that the TTF unit, which gives rise to the CT band, resides inside CBPQT^(4+)

    Establishment of Fruit Bat Cells (Rousettus aegyptiacus) as a Model System for the Investigation of Filoviral Infection

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    Marburg virus and several species of Ebola virus are endemic in central Africa and cause sporadic outbreaks in this region with mortality rates of up to 90%. So far, there is no vaccination or therapy available to protect people at risk in these regions. Recently, different fruit bats have been identified as potential reservoirs. One of them is Rousettus aegyptiacus. It seems that within huge bat populations only relatively small numbers are positive for filovirus-specific antibodies or filoviral RNA, a phenomenon that is currently not understood. As a first step towards understanding the biology of filoviruses in bats, we sought to establish a model system to investigate filovirus replication in cells derived from their natural reservoir. Here, we provide the first insights into this topic by monitoring filovirus infection of a Rousettus aegyptiacus derived cell line, R06E. We were able to show that filoviruses propagate well in R06E cells, which can, therefore, be used to investigate replication and transcription of filovirus RNA and to very efficiently perform rescue of recombinant Marburg virus using reverse genetics. These results emphasize the suitability of the newly established bat cell line for filovirus research

    Brief Exposure to Sensory Cues Elicits Stimulus-Nonspecific General Sensitization in an Insect

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    The effect of repeated exposure to sensory stimuli, with or without reward is well known to induce stimulus-specific modifications of behaviour, described as different forms of learning. In recent studies we showed that a brief single pre-exposure to the female-produced sex pheromone or even a predator sound can increase the behavioural and central nervous responses to this pheromone in males of the noctuid moth Spodoptera littoralis. To investigate if this increase in sensitivity might be restricted to the pheromone system or is a form of general sensitization, we studied here if a brief pre-exposure to stimuli of different modalities can reciprocally change behavioural and physiological responses to olfactory and gustatory stimuli. Olfactory and gustatory pre-exposure and subsequent behavioural tests were carried out to reveal possible intra- and cross-modal effects. Attraction to pheromone, monitored with a locomotion compensator, increased after exposure to olfactory and gustatory stimuli. Behavioural responses to sucrose, investigated using the proboscis extension reflex, increased equally after pre-exposure to olfactory and gustatory cues. Pheromone-specific neurons in the brain and antennal gustatory neurons did, however, not change their sensitivity after sucrose exposure. The observed intra- and reciprocal cross-modal effects of pre-exposure may represent a new form of stimulus-nonspecific general sensitization originating from modifications at higher sensory processing levels

    Structure and Functional Analysis of the RNA- and Viral Phosphoprotein-Binding Domain of Respiratory Syncytial Virus M2-1 Protein

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    Respiratory syncytial virus (RSV) protein M2-1 functions as an essential transcriptional cofactor of the viral RNA-dependent RNA polymerase (RdRp) complex by increasing polymerase processivity. M2-1 is a modular RNA binding protein that also interacts with the viral phosphoprotein P, another component of the RdRp complex. These binding properties are related to the core region of M2-1 encompassing residues S58 to K177. Here we report the NMR structure of the RSV M2-158–177 core domain, which is structurally homologous to the C-terminal domain of Ebola virus VP30, a transcription co-factor sharing functional similarity with M2-1. The partial overlap of RNA and P interaction surfaces on M2-158–177, as determined by NMR, rationalizes the previously observed competitive behavior of RNA versus P. Using site-directed mutagenesis, we identified eight residues located on these surfaces that are critical for an efficient transcription activity of the RdRp complex. Single mutations of these residues disrupted specifically either P or RNA binding to M2-1 in vitro. M2-1 recruitment to cytoplasmic inclusion bodies, which are regarded as sites of viral RNA synthesis, was impaired by mutations affecting only binding to P, but not to RNA, suggesting that M2-1 is associated to the holonucleocapsid by interacting with P. These results reveal that RNA and P binding to M2-1 can be uncoupled and that both are critical for the transcriptional antitermination function of M2-1
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