Detection and partial characterization of bacteriocin in the methanotrophic bacterium Methylobacter bovis

The strain Methylobacter bovis 98 was selected among methanotrophic bacteria as one of the most active producers of secretory bacteriocin-like compounds. In the above strain this compound was shown to be a protein with a molecular weight of about 70 kD, relatively thermostable, having a bactericidal effect on closely related organisms. Its properties as a whole are consistent with the accepted definition of bacteriocins, which so far have not been found in this group of microorganisms. A methodical approach that combines electrophoretic separation of secretory proteins and testing their antibacterial activity directly in polyacrylamide gel allowed us for the first time to identify bacteriocin in methanotrophic bacterial culture.     

The role of NF-kappaB in the angiogenic response of coronary microvessel endothelial cells

The activation of nuclear factor (NF)-kappaB by 12(R)-hydroxyeicosatrienoic acid [12(R)-HETrE], an arachidonic acid metabolite with potent stereospecific proinflammatory and angiogenic properties, was examined and its role in the angiogenic response was determined in capillary endothelial cells derived from coronary microvessels. Electrophoretic mobility-shift assay of nuclear protein extracts from cells treated with 12(R)-HETrE demonstrated a rapid and stereospecific time- and concentration-dependent increase in the binding activity of NF-kappaB, which was inhibitable by the antioxidants N-acetylcysteine, butylated hydroxyanisole, and pyrrolidine dithiocarbamate and was partially attenuated by the protein kinase C inhibitors, staurosporine and calphostin C. Neither 12(S)-HETrE nor other related eicosanoids--e.g., 12(R)-HETE, 12(S)-HETE, and leukotriene B4--stimulated the activation of NF-kappaB relative to 12(R)-HETrE, substantiating the claim for a specific receptor-mediated mechanism. 12(R)-HETrE stimulated the formation of capillary-like cords of microvessel endothelial cells distinguishable from a control; this effect was comparable to that observed with basic fibroblast growth factor (bFGF). Inhibition of NF-kappaB activation resulted in inhibition of capillary-like formation of endothelial cells treated with 12(R)-HETrE by 80% but did not affect growth observed with bFGF. It is suggested that 12(R)-HETrE's angiogenic activity involves the activation of NF-kappaB, possibly via protein kinase C stimulation and the generation of reactive oxygen intermediates for downstream signaling.     

Different O-glycosylation of respiratory mucin glycopeptides from a patient with cystic fibrosis

The O-linked oligosaccharides from three fractions of highly glycosylated mucin glycopeptides obtained from sputum of a patient with cystic fibrosis were characterized and compared regarding size, composition, sequence and when possible linkage positions. Neutral and sialic acid-containing glycans were permethylated and analyzed by high-temperature GC-MS and MALDI-MS, showing more than 60 different oligosaccharides with a size of up to 15 monosaccharide units. Some of the observed oligosaccharides are novel for respiratory secretions, one being a trifucosylated heptasaccharide with the proposed structure: Fuc-Gal-4(Fuc-3)GlcNAc-(Fuc-)Gal-3GalNAcol. The glycosylation of two of the glycopeptide fractions was similar with regard to the neutral and sialylated oligosaccharides despite their different origins from the sol or gel phase. Analysis of the sulfated oligosaccharides by FAB-MS/MS indicated that the gel fraction contained C-6 linked sulfate groups while the two sol fractions also contained C-3 linked sulfate. The results suggest the presence of different glycosylated mucin domains, probably originating from different mucin glycoforms and/or apoproteins in the airway of cystic fibrosis patients.     

On the question of an electrokinetic requirement for phospholipase C action

The phospholipase C of clostridium welchii (alpha toxin) has an absolute requirement for trace quantities of Ca2+. It attacks pure phosphatidylcholine particles (smectic mesophases) having a close-packed bilayer structure only when their surface zeta potential is made positive by the addition of certain divalent ions (e.g., Ca2+) to the aqueous phase or by the presence of low concentrations of long chain cations to the lipid. Alternatively, if the rotational freedom of individual phospholipid molecules is increased by the insertion of short n-alkanols (e.g., hexanol) into the bilayer or when a monolayer of the substrate at an air/water interface is expended, enzymic hydrolysis can occur without any requirement for a net postive charge on the surface.     

Auditory attention in hyperactive children: Effects of stimulant medication on dichotic listening performance.

Administered dichotic digit tasks requiring free report and selective listening, respectively, to 20 6–16 yr old hyperactive children. Ss received methylphenidate before 2 experimental sessions and a placebo before 2 control sessions. The stimulant did not improve free-report performance significantly; rather it facilitated or impaired performance, depending on how it affected the order in which stimuli were reported. Similarly, medication had no effect on overall selective-listening performance, but it increased the difficulty of switching attention from one ear to the other. Results demonstrate that stimulants may act to maintain selective attention and to inhibit channel switching. Listening asymmetry, that is, right-ear superiority, was influenced by task variables but not by stimulant medication. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of mini-computers for large scale structural analysis programs

One of the major new developments in computing technology is the mini-computer. This paper presents the results of the implementation of the ANSYS computer program (a large-scale structural analysis system) on a mini-computer.The implementation of ANSYS started with an evaluation of the existing and proposed mini-computer hardware and software systems, relative to a set of criteria derived from the structural software requirements.After benchmarking several systems to compare the claimed performances with the actual performance, the system which most nearly met the requirements for the ANSYS program was selected and ordered.The configuration chosen for this development machine is illustrated and variations from the development configuration which would be desirable for a production environment are discussed.The results of the implementation of ANSYS on the selected mini-computer system are presented. Included in the presentation are run times, run costs, accuracy of results and computer storage requirements.Finally, this paper discusses the future directions which will be pursued in this development effort. Included are discussions of the interface between the mini-computer and a larger central computer, the limits on problem size imposed by core memory and solution time and suggestions for the improvement of the performance of structural problems in a mini-computer environment.     

The optical (free-carrier) absorption of a hole-electron plasma in silicon

The near-IR absorption of a heavily injected silicon p-i-n diode has been measured. This is thought to be the first comprehensive measurement of the free-carrier absorption of a hole-electron plasma, and it behaves as expected with temperature, injection level and wavelength.

However, the absolute value of the absorption is higher than can be accounted for by ionized impurity scattering mechanisms by a factor of about 2.     

Verbal encoding effects on the visual short-term memory of learning disabled and normal readers.

Investigated the hypothesis that reading difficulties of learning disabled children are attributable to deficiencies in verbal encoding. Adopting a probe-type serial memory task, 60 normal and learning disabled readers matched on CA (9 yrs old), IQ, and sex were compared on recall performance after pretraining of named and unnamed stimulus conditions. The named condition for normal readers was superior in terms of recall performance. Consistent with the findings of F. Vellutino et al (1972, 1973, 1975), no difference was found in recall of nonverbal stimuli between normal and learning disabled readers. These data suggest that primary reading deficits in learning disabled children are related to verbal encoding deficiencies (visual–verbal integration) and not to deficiencies of visual memory, as suggested by the perceptual deficit hypothesis. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)