Near-field microscopy of collapsed Langmuir–Blodgett films

Fluorescence near-field scanning optical microscopy (FL-NSOM) is used to probe the nanoscale structure in stained phospholipid monolayers deposited on glass substrates at moderate surface pressures. The FL-NSOM images reveal new liquid-expanded (LE) and liquid-condensed (LC) domains, including one-to-one correlation between fluorescence contrast and film topography. In particular, films of the phospholipid DPPC stained with DiIC₁₂ exhibit multilayer structures that are observed within the solid phase domains and have LE-like fluorescence signals. These features are attributed to clusters of dye molecules resulting from the localized collapse of the film upon compression. Such collapsed features are also observed in supported films of 100% DiIC₁₂ deposited at high surface pressure. In these films, spatially-resolved spectroscopy shows that the collapsed structures are amorphous based on the fluorescence spectrum while the molecules within the solid phase of the film have a fluorescence spectrum indicative of molecular aggregates.     

Relaxational lattice dynamics in La2−xSrxCuO4 and possible connection with the stripes in cuprate superconductors

The dynamic Young’s modulus of La_2−xSr_xCuO₄ (x=0.022, 0.032) has been measured down to 1.5 K, in order to see the effect of doping on the intrinsic lattice fluctuations found in stoichiometric La₂CuO₄, and identified with tilting relaxation modes of the O octahedra. The relaxation process occurring at lower temperature drastically shifts to still lower temperatures, implying an enhancement of the corresponding relaxation rate with doping. This observation is in accordance with the hypothesis of tunnelling-driven pseudodiffusive switching of the octahedra between minima of a multiwell potential, with the distances and barriers between minima decreasing upon doping. The present measurements, together with a model of the excitations of a planar array of octahedra, provide a possible scenario for the evolution of the stripe phase in the cuprate superconductors at low doping.     

TNF mediates lung leak, but not neutrophil accumulation, in lungs of rats given IL-1 intratracheally

Interleukin-1 (IL-1) is increased in lung lavages obtained from patients with acute respiratory distress syndrome, and administering IL-1 intratracheally to rats causes an acute, neutrophil-dependent, oxidative lung leak. We found that rats given IL-1 intratracheally had increased lung lavage fluid tumor necrosis factor (TNF) levels, and that rats treated with TNF binding protein (TNFbp) intravenously did not develop the increased lung leak that occurs after administration of IL-1 intratracheally. In contrast, rats given IL-1 intratracheally and TNFbp intravenously had the same elevations in lung lavage neutrophil accumulation and lung lavage cytokine-induced neutrophil chemoattractant levels as rats given IL-1 intratracheally. Our results show that TNFbp decreases neutrophil-mediated lung leak, but not lung neutrophil accumulation, after administration of IL-1 intratracheally in rats.     

Quantification of plasma hemoglobin in the presence of bilirubin with bilirubin oxidase

Owing to the overlapping absorption bands of hemoglobin and bilirubin, spectrophotometric determination of plasma free hemoglobin has been plagued by the interference of bilirubin when the latter is present in significant concentrations. To resolve this problem, bilirubin oxidase from Myrothecium verrucaria has been used to remove bilirubin in icteric samples. The enzyme converts bilirubin to biliverdin and eliminates its absorption in the 400 nm region. The absorbance of hemoglobin at 415 nm after Allen baseline correction is used to quantify its concentration. Intra-assay precision of this method on a sample containing 200 mg/L of free hemoglobin and 200 mg/L of bilirubin is 3.1 percent (n = 10), while the between-run precision is 3.8 percent (n = 10). Accuracy studies with samples containing 200 mg/L of bilirubin yielded a straight line: y = 0.90x + 2.31, Sy.x = 3.3, r = 0.99. These results demonstrate that this method can be used to determine free hemoglobin in icteric specimens.     

Conjoined gastric and mediastinal benign cystic teratomas. Case report of a rare occurrence and review of literature

In this study, we evaluated the permeation of piperacillin (PIPC), imipenem (IPM), amikacin (AKM), gentamicin (GM), ofloxacin (OFLX), levofloxacin (LVFX), ciprofloxacin (CPFX) and sparfloxacin (SPFX) through Pseudomonas aeruginosa biofilm with a simple new method. Bacteria used were a leucine-requiring mucoid mutant. Bacteria were grown on the membrane of a cell culture insert in chemically defined medium and incubated at 37 degrees C for 5 days. At days 0, 1, 3 and 5, the penetration rates through the biofilms were measured. PIPC and IPM demonstrated relatively high permeation both with penetration rates at day 5 of 50%, whereas AMK and GM, which are aminoglycosides, showed low permeation both with penetration rates after day 1 of less than 25%. Among the 4 fluoroquinolones, LVFX and SPFX demonstrated excellent permeation with penetration rates that reached 100% from day 0 to 5, while OFLX and CPFX showed almost the same permeation as IPM. This method of measuring penetration rates of antimicrobial agents through biofilm is very simple and useful for the evaluation of antibiotics against biofilm-forming bacteria.     

Accumulation of human immunodeficiency virus-specific cytotoxic T lymphocytes away from the predominant site of virus replication during primary infection

Down-regulation of the initial burst of viremia during primary human immunodeficiency virus (HIV) infection is thought to be mediated predominantly by HIV-specific CD8+ cytotoxic T lymphocytes (CTL). This response is associated with major perturbations in the T cell receptor (TCR) repertoire. To investigate the failure of the cellular immune response to adequately control viral spread and replication and to prevent establishment of HIV infection, changes in the TCR repertoire and in the distribution of virus-specific CTL between blood and lymph node were analyzed in three patients with primary infection. By the combined use of clonotype-specific polymerase chain reaction and analysis of the frequency of in vivo activated HIV-specific CTL, it was shown that HIV-specific CTL clones preferentially accumulated in blood as opposed to lymph node. Accumulation of HIV-specific CTL in blood occurred prior to effective down-regulation of virus replication in both blood and lymph node. These findings should provide new insights into how HIV, and possibly other viruses, elude the immune response of the host during primary infection.