Positron emission tomography for the evaluation of pancreatic disease

Efficient techniques for native-labeling of amino acids have been combined successfully with emission tomography to yield significant improvements in pancreatic imaging. Carbon-11-labeled tryptophan appears to be the best agent available currently for imaging the pancreas. Optimum scanning times begin 30 min after tracer administration. Positron emission tomography with 11C-tryptophan is capable of defining both morphological and functional alterations in the pancreas. Tumors as small as 2 cm in diameter can be detected, but reliable differentiation of pancreatic cancer from pancreatis may not be possible even with this improved imaging technique. Longitudinal multiplane emission tomography in single-photon mode with the Pho/Con provides an efficient and satisfactory approach to pancreatic imaging with the positron-emitting radiopharmaceuticals.     

Domains of retinoid signalling and neurectodermal expression of zebrafish otx1 and goosecoid are mutually exclusive

Retinoid signalling plays an important role in embryonic pattern formation. Excess of retinoic acid during gastrulation results in axial defects in vertebrate embryos, suggesting that retinoids are involved in early anteroposterior patterning. To study retinoid signalling in zebrafish embryos, we developed a novel method to detect endogenous retinoids in situ in embryos, using a fusion protein of the ligand inducible transactivation domain of a retinoic acid receptor and a heterologous DNA binding domain. Using this method, we show that retinoid signalling is localized in zebrafish embryos in the region of the embryonic shield, and towards the end of gastrulation in a posterior dorsal domain. To investigate the relationships between the spatial distribution of retinoid signalling and the regulation of retinoid target genes, we studied the downregulation by retinoic acid of two genes expressed in anterior regions of the embryo, goosecoid and otx1. These experiments show that expression of both genes is strongly downregulated in the anterior neurectoderm of zebrafish embryos treated with retinoic acid, whereas mesendodermal expression is only mildly affected. Interestingly, a significant downregulation of goosecoid expression by retinoic acid was observed only during midgastrulation but not in earlier stages. In agreement with these results, spatial expression of goosecoid and otx1 does not overlap with the region of retinoid signalling in the late gastrula. Our data support the hypothesis that a localized retinoid signal is involved in axial patterning during early development, at least in part through the repression of anterior genes in posterior regions of the embryo. Furthermore, our data suggest that the action of retinoids is spatially as well as temporally regulated in the developing embryo.     

Crystalloids vs. colloids in fluid resuscitation: a systematic review

OBJECTIVE: To systematically review the effects of isotonic crystalloids compared with colloids in fluid resuscitation. DATA SOURCES: Computerized bibliographic search of published research and citation review of relevant articles. STUDY SELECTION: All randomized clinical trials of adult patients requiring fluid resuscitation comparing isotonic crystalloids vs. colloids were included. Pulmonary edema, mortality, and length of stay were evaluated. Independent review of 105 articles identified 17 relevant primary studies of 814 patients. Weighted c about article inclusion was high (0.76). DATA EXTRACTION: Data on population, interventions, outcomes, and methodologic quality of the studies were obtained by duplicate independent review with differences resolved by consensus. Weighted ic on the validity assessment was moderate (0.54). DATA SYNTHESIS: No difference was observed overall between crystalloid and colloid resuscitation with respect to mortality and pulmonary edema; however, the power of the aggregated data was insufficient to detect small but potentially clinically important differences. Subgroup analysis suggested a statistically significant difference in mortality in trauma in favor of crystalloid resuscitation (relative risk 0.39, 95% confidence intervals: 0.17 to 0.89). Several methodologic issues are noteworthy regarding the primary studies, including lack of blinding (except in three studies). The type, dose, and duration of fluid administration and outcomes measured were different across these trials. CONCLUSIONS: Overall, there is no apparent difference in pulmonary edema, mortality, or length of stay between isotonic crystalloid and colloid resuscitation. Crystalloid resuscitation is associated with a lower mortality in trauma patients. Methodologic limitations preclude any evidence-based clinical recommendations. Larger well-designed randomized trials are needed to achieve sufficient power to detect potentially small differences in treatment effects if they truly exist.     

Atomic force microscopic imaging of seeded fibril formation and fibril branching by the Alzheimer's disease amyloid-beta protein

BACKGROUND: Amyloid plaques composed of the fibrillar form of the amyloid-beta protein (Abeta) are the defining neuropathological feature of Alzheimer's disease (AD). A detailed understanding of the time course of amyloid formation could define steps in disease progression and provide targets for therapeutic intervention. Amyloid fibrils, indistinguishable from those derived from an AD brain, can be produced in vitro using a seeded polymerization mechanism. In its simplest form, this mechanism involves a cooperative transition from monomeric Abeta to the amyloid fibril without the buildup of intermediates. Recently, however, a transient species, the Abeta amyloid protofibril, has been identified. Here, we report studies of Abeta amyloid protofibril and its seeded transition into amyloid fibrils using atomic force microscopy. RESULTS: Seeding of the protofibril-to-fibril transition was observed. Preformed fibrils, but not protofibrils, effectively seeded this transition. The assembly state of Abeta influenced the rate of seeded growth, indicating that protofibrils are fibril assembly precursors. The handedness of the helical surface morphology of fibrils depended on the chirality of Abeta. Finally, branched and partially wound fibrils were observed. CONCLUSIONS: The temporal evolution of morphologies suggests that the protofibril-to-fibril transition is nucleation-dependent and that protofibril winding is involved in that transition. Fibril unwinding and branching may be essential for the post-nucleation growth process. The protofibrillar assembly intermediate is a potential target for AD therapeutics aimed at inhibiting amyloid formation and AD diagnostics aimed at detecting presymptomatic disease.     

Characterization to species level of Mycobacterium avium complex strains from human immunodeficiency virus-positive and -negative patients

Forty human clinical Mycobacterium avium-M. intracellulare complex strains isolated in Greece were characterized to the species level by PCR with three sets of primers specific for one or both species. M. avium predominated in both human immunodeficiency virus-positive and -negative patients, but the frequency of M. intracellulare isolation appeared to be higher in the latter.     

Catechol O-methyltransferase inhibitor tolcapone has minor influence on performance in experimental memory models in rats

DNA-based immunization is a promising new technique for generating antibodies in laboratory animals for diagnostic purposes in biological science. The main advantages are the elimination of time and labor and the technically demanding steps of antigen purification. The DNA sequence of the protein of interest, cloned in a suitable in vivo expression vector that is administered intramuscularly or intradermally, is sufficient to induce an immune response in animals. We report the induction of antibodies to tobacco mosaic virus (TMV) coat protein (CP) as a highly immunogenic structural protein and potato virus Y (PVY) P1 protein (P1) as a nonstructural protein. The appropriate nucleotide sequences were introduced in a mammalian expression vector (pSG5) and injected intramuscularly into New Zealand White rabbits (Oryctolagus cuniculus). By 10 days post-injection (dpi) a specific immune response was detected against TMV-CP, while it took about 5 weeks for a response to PVY P1. In both cases the antibody titers were significantly above the corresponding pre-immune serum, however, they were considerably below the titer of the matching conventionally produced antiserum. To our knowledge, this is the first report of DNA-based immunization in order to generate antibodies to plant viral proteins, but further improvements are necessary to increase antibody titers before this promising new technique can be introduced broadly in plant science for diagnostic purposes.     

Discovery of Quinoline‐Derived Trifluoromethyl Alcohols,Determination of Their in vivo Toxicity and Anticancer Activity in a Zebrafish Embryo Model

In this study the rational design, synthesis, and anticancer activity of quinoline‐derived trifluoromethyl alcohols were evaluated. Members of this novel class of trifluoromethyl alcohols were identified as potent growth inhibitors in a zebrafish embryo model. Synthesis of these compounds was carried out with an sp³‐C?H functionalization strategy of methyl quinolines with trifluoromethyl ketones. A zebrafish embryo model was also used to explore the toxicity of ethyl 4,4,4‐trifluoro‐3‐hydroxy‐3‐(quinolin‐2‐ylmethyl)butanoate ( 1 ), 2‐benzyl‐1,1,1‐trifluoro‐3‐(quinolin‐2‐yl)propan‐2‐ol ( 2 ), and trifluoro‐3‐(isoquinolin‐1‐yl)‐2‐(thiophen‐2‐yl)propan‐2‐ol ( 3 ). Compounds 2 and 3 were found to be more toxic than compound 1 ; apoptotic staining assays indicated that compound 3 causes increased cell death. In vitro cell proliferation assays showed that compound 2 , with an LC₅₀ value of 14.14 μm , has more potent anticancer activity than cisplatin. This novel class of inhibitors provides a new direction in the discovery of effective anticancer agents.