Prevention of antibiotic-associated metabolic syndrome in mice by intestinal alkaline phosphatase.

AIMS: To examine whether co-administration of intestinal alkaline phosphatase (IAP) with antibiotics early in life may have a preventive role against metabolic syndrome (MetS) in mice. METHODS: A total of 50 mice were allocated to four treatment groups after weaning. Mice were treated with azithromycin (AZT) ± IAP, or with no AZT ± IAP, for three intermittent 7-day cycles. After the last treatment course, the mice were administered a regular chow diet for 5 weeks and subsequently a high-fat diet for 5 weeks. Body weight, food intake, water intake, serum lipids, glucose levels and liver lipids were compared. 16S rRNA gene pyrosequencing was used to determine the differences in microbiome composition. RESULTS: Exposure to AZT early in life rendered mice susceptible to MetS in adulthood. Co-administration of IAP with AZT completely prevented this susceptibility by decreasing total body weight, serum lipids, glucose levels and liver lipids to the levels of control mice. These effects of IAP probably occur as a result of changes in the composition of specific bacterial taxa at the genus and species levels (e.g. members of Anaeroplasma and Parabacteroides). CONCLUSIONS: Co-administration of IAP with AZT early in life prevents mice from susceptibility to the later development of MetS. This effect is associated with alterations in the composition of the gut microbiota. IAP may represent a novel treatment against MetS in humans.

A three-dimensional model of the human facilitative glucose transporter Glut1.

The human facilitative transporter Glut1 is the major glucose transporter present in all human cells, has a central role in metabolism, and is an archetype of the superfamily of major protein facilitators. Here we describe a three-dimensional structure of Glut1 based on helical packing schemes proposed for lactose permease and Glut1 and predictions of secondary structure, and refined using energy minimization, molecular dynamics simulations, and quality and environmental scores. The Ramachandran scores and the stereochemical quality of the structure obtained were as good as those for the known structures of the KcsA K(+) channel and aquaporin 1. We found two channels in Glut1. One of them traverses the structure completely, and is lined by many residues known to be solvent-accessible. Since it is delimited by the QLS motif and by several well conserved residues, it may serve as the substrate transport pathway. To validate our structure, we determined the distance between these channels and all the residues for which mutations are known. From the locations of sugar transporter signatures, motifs, and residues important to the transport function, we find that this Glut1 structure is consistent with mutagenesis and biochemical studies. It also accounts for functional deficits in seven pathogenic mutants.

Mercurial sensitivity of aquaporin 1 endofacial loop B residues.

The water channel protein aquaporin-1 (AQP1) has two asparagine-proline-alanine (NPA) repeats on loops B and E. From recent structural information, these loops are on opposite sides of the membrane and meet to form a pore. We replaced the mercury-sensitive residue cysteine 189 in AQP1 by serine to obtain a mercury-insensitive template (C189S). Subsequently, we substituted three consecutive cysteines for residues 71-73 near the first NPA repeat (76-78) in intracellular loop B, and investigated whether they were accessible to extracellular mercurials. AQP1 and its mutants were expressed in Xenopus laevis oocytes, and the osmotic permeability (P(f)) of the oocytes was determined. C189S had wild-type P(f) but was not sensitive to HgCl(2). Expression of all three C189S cysteine mutants resulted in increased P(f), and all three mutants regained mercurial sensitivity. These results, especially the inhibitions by the large mercurial p-chloromercunbenzene-sulfonic acid (pCMBS) ( approximately 6A wide), suggest that residues 71-73 at the pore are accessible to extracellular mercurials. A 30-ps molecular dynamics simulation (at 300 K) starting with crystallographic coordinates of AQP1 showed that the width of the pore bottleneck (between Connolly surfaces) can vary (w(avg) = 3.9 A, sigma = 0.75; hydrated AQP1). Thus, although the pore width would be > or = 6 A only for 0.0026 of the time, this might suffice for pCMBS to reach residues 71-73. Alternative explanations such as passage of pCMBS across the AQP1 tetramer center or other unspecified transmembrane pathways cannot be excluded.

Presence of a fatty acid-binding protein and lipid stores in flight muscles of Dipetalogaster maximus (Hemiptera: Reduviidae).

A fatty acid-binding protein (FABP) from the cytosolic fraction of the triatomine Dipetalogaster maximus (Uhler) flight muscles was purified by a procedure based on gel filtration, reverse-phase high performance liquid chromatography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The protein has an apparent molecular mass of 14 kDa, and its N-terminus is unblocked. Its N-terminal sequence was obtained by submitting an SDS-PAGE band blotted onto a polyvinylidene difluoride membrane to Edman degradation. The sequence obtained indicates that this FABP belongs to the heart type. This is the first time that a fatty acid-binding protein has been reported for a triatomine. The presence of said FABP, abundant mitochondria, and lipid stores in the flight muscles of D. maximus suggests that beta oxidation of fatty acids is used by the triatomine thoracic muscle as an energy source, and could be related to its dispersal capacity.

[Systemic diseases and blastomas of the foot]. / Systemerkrankungen und Blastome des Fusses.

Analysis of roentgenograms by location, pattern of destruction, classification of tumor matrix and periosteal new bone formation, together with clinical data, preserves valuable information for discrimination of neoplasms in the foot. Furthermore, specific information on tumor histology and tumor extension in the bone marrow and soft tissues can be obtained by CT and MRI. Preoperative staging, guided biopsy of tumor tissue, monitoring of chemotherapeutic response and postoperative observation are further indications for MRT and other modern imaging modalities.