A natural vaccine candidate strain against cholera

E1 Tor Vibrio cholerae (EVC) strains may be classified into two kinds-epidemigenic (EEVC) strains and non-epidemigenic (NEEVC) strains-based on a phage-biotyping system. A large number of EEVC strains have been screened for toxigenic and putative colonization attributes. One such naturally occurring strains (designated IEM101) has been found which is devoid of genes encoding cholera toxin (CT), accessory cholera enterotoxin (ACE), zonula occludens toxin (ZOT), but possesses RS1 sequences and toxin-coregulated pilus A gene (icpA) although icpA is poorly expressed. It expresses type B pili but does not possess type C pili. It is an E1 Tor Ogawa strain and does not cause fluid accumulation in rabbit ilcal loop tests. Active immunization of rabbits with strain IEM101 elicited good protection against challenge with virulent strains of V. cholerae O1. Oral administration caused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses.     

Isolation of Enterobacteriaceae bacteriophage particles catalysing cell wall lipopolysaccharide degradation

Using pairs of smooth and rough forms of Enterobacteriaceae, six smooth-specific bacteriophages were isolated from sewage and another was obtained from Dr Hedda Milch, Budapest. Upon incubation of the individual extracted (smooth) host cell wall lipopolysaccharides with the homologous purified viruses, liberation of reducing groups (i.e. of about di- to nonasaccharides) was observed in four cases, indicating the action of glycanases - but no liberation of acetic acid, indicating the absence of esterase activity. Under the electron microscope, all phages were seen to exhibit Bradley group B or C morphology and to carry tail spikes.     

Accelerated evolution and molecular surface of venom phospholipase A2 enzymes

The objective of this study was to determine the in vitro shear bond strength (in megapascals) and location of bond failure with two light-cured glass ionomer resin systems. One system was a hybrid glass ionomer cement with resin (GC Orthodontics, Aslip, Ill), and the other system a glass-filled resin system (Reliance Orthodontic Products, Inc, Itasca, Ill). These systems, Fuji Ortho LC (GC Orthodontics) and Ultra Band Lok (Reliance), respectively, were compared to a light-cured composite resin. Maxillary premolar brackets (n = 200) were bonded to the facial surface of human premolar teeth. The two glass ionomer resin systems were each evaluated by two protocols, one according to the manufacturers' direction plus a variation of their respective technique. The five distinct groups (n = 40) were stored in 37 degreesC distilled water for 30 days and subjected to thermocycling before shear bond strength testing. The findings indicated that large variations existed between the bond strengths of the materials tested. The laboratory shear bond strength of the glass-filled resin glass ionomer cement (Reliance), whether tested in a dry or moist field, was similar to the composite control with all of the previous materials being significantly (P <.01) higher than both the hybrid glass ionomer cement groups (Fuji Ortho LC). However, the hybrid glass ionomer cement with enamel conditioner demonstrated a clinically acceptable mean megapascal value. The Adhesive Remnant Index values ranged from 0.53 to 1.62. The hybrid glass ionomer cement without enamel conditioning recorded the lowest mean adhesive remnant index score and the lowest mean megapascal score. Although both products are glass ionomer resin systems, their individual chemistries vary; this affects their clinical performance. Clinically, it may be suggested that glass ionomers used in a dry field may be beneficial for orthodontic bonding, and that glass ionomer resin systems used in a moist environment need an enamel conditioner.     

Molecular modeling of the Abeta1-42 peptide from Alzheimer's disease

The three-dimensional structure of the Alzheimer's disease Abeta1-42 peptide was predicted by sequence homology, threading approaches and by experimental observations. The Abeta molecule displayed a Greek key motif with four antiparallel beta-strands. To shield thermodynamically unfavorable domains, two Abeta molecules interact with each other to generate a beta-barrel structure with a hydrophilic surface and a hydrophobic core. The N-terminal domains of the dimer form crevices into which the non-polar C-termini are accommodated to yield a globular structure 27x32 A in diameter. Alternatively, the C-terminal domains of two opposing dimers could be extended to form an antiparallel beta- sheet. The stacking of these building blocks generates a helical protofilament. To create a thermodynamically more favorable structure, three protofilaments associate into a right-handed triple helix with a hydrophobic beta-sheet completely surrounded by the hydrophilic beta- barrels made of residues 1-28. Two triple helical strands can further associate into a right-handed amyloid filament. Although our model did not meet all the expected criteria, it nevertheless exhibited a series of naturally disposed structural features, revealed by other biophysical studies utilizing synthetic Abeta peptides. These characteristics are of functional significance in terms of Abeta- topology, fibril formation and cytotoxicity. The model also suggests that Abeta may not exist in a thermodynamically stable conformation, but rather as an ensemble of metastable dimeric structures some of which are capable of generating an extended C-terminal antiparallel beta-sheet essential in the promotion of fibrillogenesis.