Optimized and combined T1 and B1 mapping technique for fast and accurate T1 quantification in contrast-enhanced abdominal MRI.

Fast T(1) mapping techniques are a valuable means of quantitatively assessing the distribution and dynamics of intravenously or orally applied paramagnetic contrast agents (CAs) by noninvasive imaging. In this study a fast T(1) mapping technique based on the variable flip angle (VFA) approach was optimized for accurate T(1) quantification in abdominal contrast-enhanced (CE) MRI. Optimization methods were developed to maximize the signal-to-noise ratio (SNR) and ensure effective RF and gradient spoiling, as well as a steady state, for a defined T(1) range of 100-800 ms and a limited acquisition time. We corrected B(1) field inhomogeneities by performing an additional measurement using an optimized fast B(1) mapping technique. High-precision in vitro and abdominal in vivo T(1) maps were successfully generated at a voxel size of 2.8 x 2.8 x 15 mm(3) and a temporal resolution of 2.3 s per T(1) map on 1.5T and 3T MRI systems. The application of the proposed fast T(1) mapping technique in abdominal CE-MRI enables noninvasive quantification of abdominal tissue perfusion and vascular permeability, and offers the possibility of quantitatively assessing dilution, distribution, and mixing processes of labeled solutions or drugs in the gastrointestinal tract.     

Development ofDipetalonema viteae third-stage larvae (Nematoda: Filarioidea) in micropore chambers implanted into jirds,hamsters, normal and immunized mice

Summary Development of third-stage larvae ofDipetalonema viteae within subcutaneously implanted micropore chambers proceeded in all hosts tested up to the fourth-stage larvae and occasionally to adolescent worms. In the jird the timing of development was comparable to a natural infection. Although the mouse is an insusceptible host, larval development could take place, but was very slow. Two intraperitoneal inoculations of living thirdstage larvae into mice induced the production of antibodies against the larval cuticle and against common antigens. In such immune mice the development of third- and fourth-stage larvae within micropore chambers was significantly inhibited, larval mortality was increased, and the larval motility was impaired.     

Tapping allergen repertoires by advanced cloning technologies

BACKGROUND: Complex allergenic sources such as moulds, foods and mites contain complex panels of IgE-binding molecules which need to be cloned, produced and characterized in order to mimic the entire allergenicity of whole extracts reconstituted by mixing single standardized recombinant allergens. METHODS: Phage surface display of cDNA libraries selectively enriched for allergen-expressing clones using IgE from allergic patients allows rapid isolation of large panels of allergens. For the characterization of all different clones present in enriched cDNA libraries in a fast and cost-effective way, high-throughput screening technology is required. RESULTS: The combination of selective enrichment of cDNA libraries based on biopanning against serum IgE from sensitized patients and automated robot technology for picking and high-density gridding of clones onto filter membranes, followed by hybridization, enables fast identification of all the different clones present in an enriched library. The consequent application of selective enrichment and robotic-based screening allows, within weeks, cloning and characterization of the whole allergenic repertoire of any organisms. CONCLUSIONS: Robotic-based high-throughput screening of clones selected for IgE-binding capacity from phage surface-displayed cDNA libraries of Aspergillus fumigatus, Cladosporium herbarum, Coprinus comatus, Malassezia furfur, peanut and human lung tissue allowed rapid characterization of 81, 28, 37, 27, 8 and 151 different sequences, respectively. All these cDNAs bear a high probability to encode allergens derived from the respective allergenic source.     

IGF-I and vanadate stimulate Na/Pi-cotransport in OK cells by increasing type II Na/Pi-cotransporter protein stability

 Insulin-like growth factor (IGF)-I and vanadate increase Na-dependent phosphate (Na/P_i) cotransport in opossum kidney (OK) cells. To gain more information about the mechanisms by which IGF-I and vanadate stimulate Na/P_i-cotransport, we measured type II Na/P_i-cotransporter (NaPi-4) protein abundance by Western blot analysis and investigated the effects of protein synthesis and tyrosine kinase inhibitors. The key findings in the present studies are as follows. First, incubation in IGF-I (10^–8 M) and/or vanadate (10^–3 M) for 3 h led to a non-additive 1.4-fold increase in Na/P_i-cotransport activity which was paralleled by a 1.5- to 2-fold increase in NaPi-4 protein. Second, actinomycin D did not abolish the increase in Na/P_i-cotransport and cycloheximide did not prevent the IGF-I-induced increase in Na/P_i-cotransport and NaPi-4 protein. Third, among the protein kinase inhibitors tested, only staurosporine substantially reduced the stimulation of Na/P_i-cotransport. In conclusion, the stimulatory effect of IGF-I on Na/P_i-cotransport is paralleled by an increased expression of NaPi-4 protein that is independent of protein synthesis and therefore results from increased protein stability. The observation that IGF-I and/or vanadate lead to similar increases in Na/P_i-cotransport and NaPi-4 protein abundance provides further evidence that the stimulation of Na/P_i-cotransport by IGF-I and vanadate involves protein tyrosine phosphorylation of the same signalling molecules. Received: 1 May 1998 / Received after revision: 25 August 1998 / Accepted: 1 September 1998     

Inbreeding Affects Female Preference for Symmetry in Computer-Animated Sticklebacks

Fluctuating asymmetries are small random deviations from perfect symmetry in bilateral traits caused by the inability of individuals to cope with stress during development. The degree of asymmetry of secondary sexual characters is supposed to convey information about a male's phenotypic and/or genetic quality, and females are thus expected to use bilateral symmetry as a cue in mate choice. We offered female three-spined sticklebacks (Gasterosteus aculeatus L.) that had been inbred for one generation and outbred control females the choice between computer-animated male models differing exclusively in the symmetry of their pelvic spines. Inbred females exhibited a significantly stronger preference for the symmetric model than outbred females, suggesting that females of relatively poor quality are more prepared to pay the costs of choosiness and obtain higher marginal benefits from their discrimination than females of better quality.     

Ectopic bone formation associated with mesenchymal stem cells in a resorbable calcium deficient hydroxyapatite carrier

Bone substitute materials can induce bone formation in combination with mesenchymal stem cells (MSC). The aim of the current study was to examine ectopic in vivo bone formation with and without MSC on a new resorbable ceramic, called calcium deficient hydroxyapatite (CDHA). Ceramic blocks characterized by a large surface (48 m2/g) were compared with beta-tricalcium phosphate (beta-TCP), hydroxyapatite (HA) ceramics (both ca. 0.5 m2/g surface) and demineralized bone matrix (DBM). Before implantation in the back of SCID mice carriers were freshly loaded with 2x10(5) expanded human MSC or loaded with cells and kept under osteogenic conditions for two weeks in vitro. Culture conditions were kept free of xenogenic supplements. Deposits of osteoid at the margins of ceramic pores occurred independent of osteogenic pre-induction, contained human cells, and appeared in 416 MSC/CDHA composites compared to 216 MSC/beta-TCP composites. ALP activity was significantly higher in samples with MSC versus empty controls (p<0.001). Furthermore, ALP was significantly (p<0.05) higher for all ceramics when compared to the DBM matrix. Compared to previous studies, overall bone formation appeared to be reduced possibly due to the strict human protocol. Ectopic bone formation in the novel biomaterial CDHA varied considerably with the cell pool and was at least equal to beta-TCP blocks.     

The cleavage activation and sites of glycosylation in the fusion protein of Hendra virus

Hendra virus (HeV) is an unclassified member of the Paramyxoviridae family that causes systemic infections in humans, horses, cats, guinea pigs and flying foxes. The fusion protein (F(0)) of members of the Paramyxoviridae family that cause systemic infections in vivo contains a basic amino acid-rich region at which the protein is activated by cleavage into two subunits (F(1) and F(2)). HeV F(0) lacks such a domain. We have determined the cleavage site in HeV F(0) by sequencing the amino terminus of the F(1) subunit and in view of the potential effect of glycosylation on the cleavage process have ascertained the sites at which F(0) is glycosylated. The results indicate that unlike other members of the family that replicate in cultured cells and cause systemic infections in vivo, cleavage of HeV F(0) occurs at a single lysine (reside 109) in the sequence Asp-Val-Lys- downward arrow-Leu. Although HeV genotypically resembles members of the Respirovirus and Rubulavirus genera in having potential N-linked glycosylation sites in both the F(1) and F(2) subunits, we show that phenotypically HeV may more closely resemble members of the Morbillivirus genus that contain N-linked glycans only in the F(2) subunit.