Measurement of ion-induced noise in atmospheric counting chambers,and a novel chamber for its elimination

Atmospheric small-ion enhancement is widely employed in medical, physiological and horticultural research. Accurate measurements of both positive and negative ion concentrations are then essential, but in the face of the high ion ratios encountered — up to 10³ — the classical two-electrode counter is unable to measure the ion of low concentration. It is found that the reading is obliterated by noise.The phenomenon is demonstrated and the theory of counting chambers is extended to include it. A novel three-electrode chamber which is free from ion-induced noise is then designed and the Paper concludes with the test results obtained by its use.     

Cholecystokinin elevates cytosolic calcium in small cell lung cancer cells

The ability of cholecystokinin (CCK) to elevate intracellular Ca2+ levels in small cell lung cancer cells was investigated using the fluorescent Ca2+ indicator Fura 2. CCK-8 elevated the cytosolic Ca2+ levels in cell line NCI-H345 in a dose dependent manner. Nanomolar concentration of CCK-8 elevated cytosolic Ca2+ levels in the absence or presence of extracellular Ca2+. Potent CCK agonists such as gastrin-1 and nonsulfated CCK-8 but not inactive compounds such as CCK-27-32-NH2 elevated cytosolic Ca2+ levels. These data suggest that CCK receptors may regulate the release of Ca2+ from intracellular organelles in small cell lung cancer cells.     

Geometry of phage head construction.

The process of phage capsid assembly is reviewed, with particular attention to the probable role of curvature in helping to determine head size and shape. Both measures of curvature (mean curvature and Gaussian curvature, explained in Appendix I), should act best when the assembling shell is spherical, which could account for procapsids having this shape. Procapsids are also relatively thick, which should help head size determination by the mean curvature. The accessory role of inner and outer scaffolds in size determination and head nucleation is also reviewed.Nucleation failure generates various malformations, including non-closure, but the most common is the tube or polyhead, where the subunits' inherent curvature is expressed as a constant mean curvature. This induces lattice distortions that only partly understood. An extra tubular section in normal heads leads to the prolate shape, with a more complex and variable geometry.Newly assembled procapsids are both enlarged and toughened by the head transformation. In the procapsid the Gaussian curvature is uniformly distributed. But toughening tends to equalize bond lengths, so all the Gaussian curvature gets concentrated in the vertices, being zero elsewhere. This explains head angularization. Because of this change in Gaussian curvature, the regular subunit packing in the polyhedral head cannot be mapped onto the procapsid. This explains part of the hexon distortions found in this region.The implications of translocase-induced DNA twist, end rotation and the coiling of packaged DNA, are discussed.The symmetry mismatches between the head, connector and tail are discussed in relation to the possible alpha-helical structures of their DNA channels.     

Lipidomic profiling of model organisms and the world's major pathogens

Lipidomics is a subspecialty of metabolomics that focuses on water insoluble metabolites that form membrane barriers. Most lipidomic databases catalog lipids from common model organisms, like humans or Escherichia coli. However, model organisms' lipid profiles show surprisingly little overlap with those of specialized pathogens, creating the need for organism-specific lipidomic databases. Here we review rapid progress in lipidomic platform development with regard to chromatography, detection and bioinformatics. We emphasize new methods of comparative lipidomics, which use aligned datasets to identify lipids changed after introducing a biological variable. These new methods provide an unprecedented ability to broadly and quantitatively describe lipidic change during biological processes and identify changed lipids with low error rates.     

Stereospecific reversal of nitrous oxide analgesia by naloxone

The opiate antagonist naloxone was found to block nitrous oxide analgesia in a stereospecific fashion. Using a modified hotplate test in mice, the (-)-enantiomer of naloxone (which has a KD of approximately 1 nM for opiate receptors) antagonized the analgesic actions of nitrous oxide in a dose-dependent (2.5-20 mg/kg) fashion. In contrast, the (+)-enantiomer (KD approximately 10,000 nM) had no effect on nitrous oxide analgesia at the highest dose tested (40 mg/kg). These data strongly suggest that nitrous oxide analgesia is mediated via opiate receptors and is consistent with the hypotheses that this effect occurs either through the release of endogenous opioids or by physical perturbation of the opiate receptors.