Antigen responsiveness of an established human B-lymphoid cell line I. Evidence for a surface receptor for Candida antigen detected by direct migration inhibition

Responsiveness to a soluble crude Candida albicans antigen (CaAg) by a long-term human lymphoid cell line with B-cell characteristics (PGLC-33H) is demonstrated by the direct migration inhibition (DMI) assay. An inability to detect comparable CaAg responses in other tested B- and T-lymphoid cell lines suggests that this may be a specific response for PGLC-33H cells. CaAg responsiveness is completely abrogated by trypsinization of cells. Regeneration of CaAg responsiveness is temperature dependent, detectable in 8–14 hr in cells maintained at 37°C. Trypsinized cells kept at 4°C do not regain CaAg response. The rate of cell-CaAg interaction is rapid and not temperature dependent. Cells pulsed with CaAg at 37, 25, and 4°C demonstrate comparable DMI responses following a 2-min pulse with CaAg. These findings suggest that PGLC-33H cells have surface receptors for CaAg which result in the inhibition of cell migration upon exposure to antigen.     

Seed dormancy of Cardiospermum halicacabum (Sapindaceae) from three precipitation zones in Sri Lanka

• This study investigated seed germination of Cardiospermum halicacabum, a medicinally important invasive species.
• We compared mass, moisture content (MC), dormancy and dormancy‐breaking treatments and imbibition and germination of scarified and non‐scarified seeds of C. halicacabum from a low‐elevation dry zone (DZ), low‐elevation wet zone (WZ1) and mid‐elevation wet zone (WZ2) in Sri Lanka to test the hypothesis that the percentage of seeds with water‐impermeable seed coats (physical dormancy, PY) decreases with increased precipitation.
• Seed mass was higher in WZ2 than in DZ and WZ1, while seed MC did not vary among the zones. All scarified DZ, WZ1 and WZ2 and non‐scarified DZ and WZ1 seeds imbibed water, but only a few non‐scarified WZ2 seeds did so. When DZ and WZ1 seeds were desiccated, MC and percentage imbibition decreased, showing that these seeds have the ability to develop PY. GA₃ promoted germination of embryos excised from fresh DZ and WZ1 seeds and of scarified WZ2 seeds.
• At maturity, seeds from DZ and WZ1 had only physiological dormancy (PD), while those from WZ2 had combinational dormancy (PY+PD). Thus, our hypothesis was not supported. Since a high percentage of excised embryos developed into normal seedlings; this is a low‐cost method to produce C. halicacabum plants for medicinal and ornamental purposes.

     

Echocardiographic assessment and percutaneous closure of multiple atrial septal defects

Percutaneous coronary intervention can be associated with distal embolization of thrombotic material causing myocardial necrosis and infarction. We discuss the role of intravascular imaging to guide the use of a distal protection device by describing the outcome of a young woman presenting with non-ST elevation myocardial infarction. Coronary angiography demonstrated an isolated minor stenosis in the proximal left anterior descending coronary artery with slight haziness beyond the lesion. Intravascular ultrasound confirmed an extensive thrombus overlying a bulky atherosclerotic plaque. A distal filter wire was therefore successfully used to reduce the risk of distal embolization. The use of intravascular ultrasound in patients presenting with acute coronary syndrome may reveal large thrombi that are difficult to image using conventional angiographic techniques. Intravascular ultrasound can therefore be used as a tool to select lesions requiring distal protection.     

Encephalomyocarditis virus infection in African green and squirrel monkeys: comparison of pathologic effects

This study compared the pathological effects of experimental encephalomyocarditis virus infection in African green monkeys (Cercopithecus aethiops) and squirrel monkeys (Saimiri sciureus). African green monkeys died within 5 days post-inoculation and significant changes were limited to moderate to severe multifocal nonsuppurative necrotizing myocarditis. Squirrel monkeys were less severely affected and died or were euthanized 4 to 41 days post-inoculation. Myocardial and central nervous system changes in squirrel monkeys were minimal to moderate and variable in distribution, while pancreatic changes were more severe and included multifocal necrosis, subacute inflammation and atrophy of exocrine cells.     

Sites of cleavage of glucagon by insulin-glucagon protease.

To study the mechanism of degradation of glucagon with purified insulin-glucagon protease, glucagon was reacted with the enzyme at various times of incubation. The proteolysis was followed by the production of flourescamine-reacting material as well as reaction with dansyl chloride, cleavage by acid hydrolysis, and identification by thin layer chromatography. For quantitative measurement of the degradation products, [¹⁴C] dansyl derivatives were produced, identified by autoradiography, and counted. In the degradation products in addition to histidine, the dansyl derivatives of tyrosine, phenylalanine, two leucines, alanine and lysine were identified. For comparison, glucagon was also reacted with chymotrypsin and the degradation products consisted of threonine, serine, two leucines and valine. Thus, insulin-glucagon protease degrades glucagon in a manner distinct from that of chymotrypsin.     

A systematic screen for genes expressed in definitive endoderm by Serial Analysis of Gene Expression (SAGE)

Background  

The embryonic definitive endoderm (DE) gives rise to organs of the gastrointestinal and respiratory tract including the liver, pancreas and epithelia of the lung and colon. Understanding how DE progenitor cells generate these tissues is critical to understanding the cause of visceral organ disorders and cancers, and will ultimately lead to novel therapies including tissue and organ regeneration. However, investigation into the molecular mechanisms of DE differentiation has been hindered by the lack of early DE-specific markers.     

Accurate prediction of protein secondary structure and solvent accessibility by consensus combiners of sequence and structure information

Background  

Structural properties of proteins such as secondary structure and solvent accessibility contribute to three-dimensional structure prediction, not only in the ab initio case but also when homology information to known structures is available. Structural properties are also routinely used in protein analysis even when homology is available, largely because homology modelling is lower throughput than, say, secondary structure prediction. Nonetheless, predictors of secondary structure and solvent accessibility are virtually always ab initio.     

Methods for peptide identification by spectral comparison

Background  

Tandem mass spectrometry followed by database search is currently the predominant technology for peptide sequencing in shotgun proteomics experiments. Most methods compare experimentally observed spectra to the theoretical spectra predicted from the sequences in protein databases. There is a growing interest, however, in comparing unknown experimental spectra to a library of previously identified spectra. This approach has the advantage of taking into account instrument-dependent factors and peptide-specific differences in fragmentation probabilities. It is also computationally more efficient for high-throughput proteomics studies.