A framework for optical burst switching network design

We analyze optical burst switching (OBS) systems. The analysis leads to a framework which provides guidelines for OBS design. We identify conditions for OBS feasibility and the relationship between burst size, or equivalently burst assembly delay, and throughput, taking into consideration control packet processing and the number of available wavelengths per fiber     

Optimization of the dispersion of gold and platinum nanoparticles on indium tin oxide for the electrocatalytic oxidation of cysteine and arsenite

Gold and platinum nanoparticles (NPs) were prepared by chemical reduction of the corresponding metal complex bound by ion-exchange to generation-4 poly(amidoamine) dendrimers (PAMAM). Arrays of the NPs on indium tin oxide (ITO) electrodes were formed by adsorbing a monolayer comprising a controlled ratio of NP-PAMAM to PAMAM on ITO that was modified with 3-aminopropyl triethoxysilane; subsequently, the organic components were thermally destroyed. Varying the above-defined ratio resulted in a commensurate change of the density of the NPs on the surface. Using an electrode modified in a solution with a mole fraction of Au-PAMAM (relative to total of Au-PAMAM and PAMAM) of 0.06, which gave NPs separated by 200 nm, the current for the catalytic oxidation of cysteine reached a value that did not increase when more nanoparticles were present. The analogous experiment on the oxidation of As^III with PtNPs as the catalyst was optimized at a mole fraction of 0.2. Calculations assuming hemispherical diffusion suggested that the diffusion domains during cyclic voltammetry at 5 mV s⁻¹ were less than the distance between the NPs.     

Expression of deletion-containing dystrophins in mdx muscle: implications for gene therapy and dystrophin function

The expression of full-length dystrophin and various dystrophin deletion mutants was monitored in mdx mouse muscle after intramuscular injection of dystrophin-encoding plasmid DNAs. Recombinant dystrophin proteins, including those lacking either the amino terminus, carboxyl terminus, or most of the central rod domain, showed localization to the plasma membrane. This suggests that there are multiple attachment sites for dystrophin to the plasma membrane. Only those constructs containing the carboxyl terminus were able to stabilize dystrophin-associated proteins (DAP) at the membrane, consistent with other studies that suggest that this domain is critical to DAP binding. Colocalization with DAP was not necessary for membrane localization of the various dystrophin molecules. However, stabilization and co-localization of the DAP did seem to be a prerequisite for expression and/or stabilization of mutant dystrophins beyond 1 wk and these same criteria seemed important for mitigating the histopathological consequences of dystrophin deficiency.     

Longitudinal studies of immune function in cattle experimentally infected with bovine immunodeficiency-like virus and/or bovine leukemia virus

The effects of single or dual infection with bovine immunodeficiency-like virus (BIV) and/or, bovine leukemia virus (BLV) on bovine immune function were examined over a 4 year period. Holstein calves were infected with BIV (four calves), BLV (five calves), BIV and BLV (five calves), or sham inoculated (three calves). Lymphocyte blastogenesis to mitogens, seven tests of neutrophil function, and mononuclear cell subset analysis by flow cytometry (BoCD4, BoCD8, BoCD2, BoWC1, sIgM+, and monocytes) were performed at regular intervals to 49 months post-infection. These data were analyzed for main effects of each virus and interaction as a 2 x 2 factorial. BIV infected cattle had lower neutrophil antibody-dependent cell-mediated cytotoxicity and iodination responses during 2 of the 4 years post-infection (P < 0.05). BIV infection was not associated with any long-term significant changes in lymphocyte blastogenesis to mitogens or changes in mononuclear cell subset numbers in blood. There was a tendency for animals infected with BIV alone to have decreased lymphocyte blastogenic responses to mitogens, but this was not statistically significant. BLV infection caused an increase in total mononuclear cells with no dramatic shift in the relative proportions of the various subsets. Co-infection with BIV and BLV did not consistently cause a different response than either virus did individually. One BIV infected animal died of non-BLV lymphosarcoma 7 months after infection. All other animals had no unusual clinical signs. In summary, infection with BIV caused a significant, temporary decrease in neutrophil function with no consistent statistically significant alteration in lymphocyte blastogenesis or mononuclear cell numbers during the first 4 years after infection. BLV infection caused an increase in lymphocyte numbers, and there appeared to be no synergism between the viruses.     

Cellular localization of the chemokine receptor CCR5. Correlation to cellular targets of HIV-1 infection

The chemokine receptor CCR5 has recently been described as a co-receptor for macrophage-tropic strains of human immunodeficiency virus (HIV)-1. In this study, using a panel of monoclonal antibodies specific for human CCR5, we show by immunohistochemistry and flow cytometry that CCR5 is expressed by bone-marrow-derived cells known to be targets for HIV-1 infection, including a subpopulation of lymphocytes and monocyte/macrophages in blood, primary and secondary lymphoid organs, and noninflamed tissues. In the central nervous system, CCR5 is expressed on neurons, astrocytes, and microglia. In other tissues, CCR5 is expressed on epithelium, endothelium, vascular smooth muscle, and fibroblasts. Chronically inflamed tissues contain an increased number of CCR5+ mononuclear cells, and the number of immunoreactive cells is directly associated with a histopathological correlate of inflammatory severity. Collectively, these results suggest that CCR5+ cells are recruited to inflammatory sites and, as such, may facilitate transmission of macrophage-tropic strains of HIV-1.     

Extent of radial sarcomere coupling revealed in passively stretched cardiac myocytes

We report a simple method, the PinPoint assay, for detecting and identifying single-base variations (polymorphisms) at specific locations within DNA sequences. An oligonucleotide primer is annealed to the target DNA immediately upstream of the polymorphic site and is extended by a single base in the presence of all four dideoxynucleotide triphosphates and a thermostable DNA polymerase. The extension products are desalted, concentrated, and subjected to delayed-extraction MALDI-TOF mass spectrometry. The base at the polymorphic site is identified by the mass added onto the primer. Heterozygous targets produce two mass-resolved species that represent the addition of both bases complementary to those at the polymorphic site. The assay is suitable for double-stranded PCR products without purification or strand separation. More than one primer can be simultaneously extended and then mass-analyzed. The mass spectrometric method thus shows promise for high-volume diagnostic or genotyping applications.     

A proposal for minimum detectable compartment in MIRD dosimetry modelling

The accuracy of radiation dose estimates from radiopharmaceutical administrations has recently become more important for three main reasons: (i) clinical providers are demanding more information on diagnostic procedures; (ii) regulatory groups are scrutinizing dosimetry for research subjects; and (iii) accurate organ doses are crucial in therapeutic administrations. These dose estimates are a sensitive function of the residence times. Because most clinical data acquisition protocols are limited to the first 24 h after dose administration, the area under the remainder of the time-activity curve (TAC) must be estimated. Estimation methods range from assuming physical decay only (overly conservative) to extrapolating end point physiological kinetics (overly liberal). This study demonstrates how much the results from these two methods vary and develops an alternative method which more accurately estimates this remainder term. A method, called the minimum detectable compartment (MDC), is constructed so that an accurate dose estimate can be made with a realistic measure of the remainder term. The method for determining MDC uses standard hypothesis testing. Using an analogue of the traditional minimal detectable activity calculation, a model with and without constant compartments is fitted to the TAC. The size of the constant compartment is varied until the relative likelihood of the two models meets the desired measure of power and sensitivity. Computer simulations of a simple mono-exponential are used to demonstrate the MDC as a function of the model, the number of data points, the range of the data and the noise in the data. The MDC is a very sensitive function of the data range. It falls by more than 50% when the data range is increased from two to three half-lives. In addition, the MDC is moderately sensitive to the noise in the data and relatively insensitive to the number of data points. These findings suggest that the MDC method can also be uses a priori to indicate what type of data collection regimen is necessary to achieve a certain accuracy.     

Staphylococcal culture supernates stimulate human phagocytes

c-fos induction was investigated as a potential component in the avian photic entrainment pathway and as a possible means of locating the central pacemaker in birds. In both quail (Coturnix coturnix japonica) and starlings (Sturnus vulgaris) exposure to 1 h of light induced Fos-lir in the visual suprachiasmatic nucleus but not in the medial suprachiasmatic nucleus. However, the degree of c-fos induction in the visual suprachiasmatic nucleus was similar at different circadian times despite the fact that the light pulses caused differential phase shifts in the locomotor rhythm. For golden hamsters the same experiment resulted in significantly different levels of Fos-lir in the suprachiasmatic nucleus, as well as different phase shifts. Starlings and hamsters were also entrained to T-cycles that caused a large daily phase shift (T = 21.5 h in starlings, T = 22.67 hours in hamsters), or no daily phase shift (T = free running period). No difference in the induced levels of Fos-lir in the visual suprachiasmatic nucleus region was observed between the two groups of starlings, but in hamsters there were significantly different levels of Fos-lir in the suprachiasmatic nucleus between the two groups.