Effect of lifestyle factors on Staphylococcus aureus gut colonization in Swedish and Italian infants

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Architecture, Space and Information in Constructions Built by Humans and Social Insects: a Conceptual Review

The similarities between the structures built by social insects and by humans have led to a convergence of interests between biologists and architects. This new, de facto interdisciplinary community of scholars needs a common terminology and theoretical framework in which to ground its work. In this conceptually oriented review paper, we review the terms “information”, “space” and “architecture” to provide definitions that span biology and architecture. A framework is proposed on which interdisciplinary exchange may be better served, with the view that this will aid better cross fertilisation between disciplines, working in the areas of collective behaviour and analysis of the structures and edifices constructed by non-humans; and to facilitate how this area of study may better contribute to the field of architecture. We then use these definitions to discuss the informational content of constructions built by organisms and the influence these have on behaviour, and vice versa. We review how spatial constraints inform and influence interaction between an organism and its environment, and examine the reciprocity of space and information on construction and the behaviour of humans and social insects

EFFECT OF 2.45 GHZ MICROWAVE-RADIATION ON PERMEABILITY OF UNILAMELLAR LIPOSOMES TO 5(6)-CARBOXYFLUORESCEIN - EVIDENCE OF NONTHERMAL LEAKAGE

The influence of 2.45 GHz microwave radiation on the membrane permeability of unilamellar liposomes was studied using the marker 5(6)-carboxyfluorescein trapped in phosphatidylcholine liposomes. The release of the fluorescent marker was followed by spectrofluorimetry after an exposure of 10 minutes to either microwave radiation or to heat alone of the liposome solutions. A significant increase of the permeability of carboxyfluorescein through the membrane was observed for the microwave-exposed samples compared to those exposed to normal heating only. Exposure to 2.45 GHz microwave radiation of liposomes has been previously found to produce increased membrane permeability as compared with heating. However, in contrast to previous studies, the observations reported here were made above the phase transition temperature of the lipid membrane. The experimental setup included monitoring of the temperature during microwave exposure simultaneously at several points in the solution volume using a fiberoptic thermometer. Possible mechanisms to explain the observations are discussed

Superantigens and adhesins of infant gut commensal Staphylococcus aureus strains and association with subsequent development of atopic eczema

International audienceBACKGROUND: According to the hygiene hypothesis, insufficient immune activation by microbes increases the risk of allergy development. Staphylococcus aureus, which is part of the skin and gut microbiota of infants in Western countries, produces a variety of T-cell-activating enterotoxins, called superantigens. OBJECTIVES: To investigate whether early (0-2 months of age) gut colonization by S. aureus strains that carry specific superantigens and adhesins was related to subsequent development of atopic eczema in a Swedish birth cohort. METHODS: Staphylococcus aureus was isolated from rectal swabs and cultured quantitatively from faecal samples, with individual strains being tested for carriage of genes for superantigens and adhesins. Atopic eczema was diagnosed at onset of symptoms and at 18 months of age. RESULTS: Although the frequency of early gut colonization by S. aureus was not related to subsequent eczema development, the S. aureus strains that were found to colonize those infants who developed atopic eczema were less likely to carry the gene encoding the superantigen SElM (P = 0\textperiodcentered008) and the gene for elastin-binding protein (P = 0\textperiodcentered03), compared with strains that were isolated from infants who had not developed atopic eczema by 18 months of age. CONCLUSIONS: Gut colonization by S. aureus strains carrying a certain combination of superantigen and adhesin genes was negatively associated with subsequent development of atopic eczema. Such strains may provide stimulation and promote maturation of the infant immune system

High Rate of Transfer of Staphylococcus aureus from Parental Skin to Infant Gut Flora

Many Swedish infants carry Staphylococcus aureus in their intestinal microflora. The source of this colonization was investigated in 50 families. Infantile S. aureus strains were isolated from rectal swabs and stool samples at 3 days and at 1, 2, 4, and 8 weeks of age. The strains were identified by using the random amplified polymorphic DNA method and compared to strains from swab cultures of the mothers' hands, nipples, and nares and from the fathers' hands and nares. Maternal stool samples were also obtained at a later stage to compare infant and adult intestinal S. aureus colonization. Although 60% of 1-month-old children had S. aureus in the stools, this was true of only 24% of the mothers. The median population numbers in colonized individuals also differed: 10(6.8) CFU/g of feces among infants at 2 weeks of age versus 10(3.2) CFU/g of feces in the mothers. Of S. aureus strains in the stools of 3-day-old infants, 90% were identical to a parental skin strain. A total of 96% of infants whose parents were S. aureus skin carriers had S. aureus in their feces and 91% had the same strain as at least one of the parents. In comparison, only 37% of infants to S. aureus-negative parents had S. aureus in the stool samples. Thus, infantile intestinal S. aureus colonization was strongly associated with parental skin S. aureus carriage (P = 0.0001). These results suggest that S. aureus on parental skin establish readily in the infantile gut, perhaps due to poor competition from other gut bacteria

Avidity progression of dietary antibodies in healthy and coeliac children

In most individuals minute amounts of food proteins pass undegraded across the intestinal mucosa and trigger antibody formation. Children with coeliac disease have enhanced antibody production against gliadin as well as other dietary antigens, e.g. β-lactoglobulin, in cow's milk. Antibody avidity, i.e. the binding strength between antibody and antigen, often increases during antibody responses and may be related to the biological effectiveness of antibodies. The aim of the present study was to determine the avidity of serum IgG antibodies against β-lactoglobulin and gliadin in healthy children during early childhood and compare these avidities to those found in children with coeliac disease. The average antibody avidity was analysed using a thiocyanate elution assay, whereas the antibody activity of the corresponding sera was assayed by ELISA. The avidity of serum IgG antibodies against β-lactoglobulin as well as gliadin increased with age in healthy children, even in the face of falling antibody titres to the same antigens. Children with untreated coeliac disease had IgG anti-β-lactoglobulin antibodies of significantly higher avidity than healthy children of the same age, and the same trend was observed for IgG antigliadin antibodies. The present data suggest that the avidities of antibodies against dietary antigens increase progressively during early childhood, and that this process seems to be accelerated during active coeliac disease

Lactobacilli in the intestinal microbiota of Swedish infants

Lactobacillus colonisation was examined in 112 Swedish infants. Faecal samples obtained at 1, 2,4 and 8 weeks and at 6, 12 and 18 months of age were cultivated quantitatively on Rogosa agar. Lactobacilli were speciated by PCR and typed to the strain level by randomly amplified polymorphic DNA (RAPD). Lactobacilli reached a peak at 6 months when 45% of the infants were colonised. L. rhamnosus and L. gasseri were the most common species in this period. Colonisation by lactobacilli in general (P < 0.01) and L. rhamnosus in particular (P < 0.05) was more common in breast-fed than in weaned infants at 6 months of age. Lactobacillus isolation reached a nadir of 17% by 12 months (P < 0.0001), but increased to 31% by 18 months of age (P < 0.05). The food-related species L. paracasei, L. plantarum, L. acidophilus and L. delbrueckii dominated in this second phase. A single strain persisted for at least 3 weeks in 17% of the infants during the first 6 months, most commonly L. rhamnosus. Lactobacillus population counts in colonised infants increased from 10(6.4) cfu/g at I week to 10(8.8) cfu/g at 6 months, and then dropped to 10(5.4) cfu/g faeces at 12 months of age. Lactobacillus colonisation was not significantly related to delivery mode, or to presence of siblings or pets in the household. Our results suggest that certain Lactobacillus species, especially L. rhamnosus, thrive in the intestinal flora of breast-fed infants. After weaning they are replaced by other Lactobacillus species of types found in food. (c) 2005 Elsevier SAS. All rights reserved