Sensitivity of a superconducting nanowire detector for single ions at low energy

We report on the characterization of a superconducting nanowire detector for ions at low kinetic energies. We measure the absolute single-particle detection efficiency η and trace its increase with energy up to η = 100%. We discuss the influence of noble gas adsorbates on the cryogenic surface and analyze their relevance for the detection of slow massive particles. We apply a recent model for the hot-spot formation to the incidence of atomic ions at energies between 0.2 and 1 keV. We suggest how the differences observed for photons and atoms or molecules can be related to the surface condition of the detector and we propose that the restoration of proper surface conditions may open a new avenue for SSPD-based optical spectroscopy on molecules and nanoparticles.     

Composition and function of peripheral blood stem and progenitor cell harvests from patients with severe active rheumatoid arthritis

High-dose chemotherapy with autologous stem cell rescue has been proposed as an intensive therapy for severe rheumatoid arthritis (RA). In view of previous observations of abnormal haemopoiesis in RA patients, the composition and function of peripheral blood stem cell harvests (PBSCH) was investigated. Compared with PBSCH from healthy allogeneic donors mobilized with the same dose of G-CSF (filgrastim; 10 microg/kg/d, n = 14), RA PBSCH (n = 9) contained significantly fewer mononuclear cells (375 v 569 x 10(6)/kg, P = 0.03) and CD34+ cells (2.7 v 5.8 x 10(6)/kg, P = 0.003). However, there were increased proportions of CD14+ cells (P = 0.006) and CD14+ CD15+ cells (the phenotype of previously described 'abnormal' myeloid cells, P = 0.002) in the RA PBSCH which translated into 3.5- and 7-fold increases respectively on a per CD34+ cell basis. There were no differences in T-cell activation status as judged by proportions of CD4+ and CD8+ expressing CD45RA, CD45RO, HLA-DR and CD28 (RA PBSCH, n = 7, donor PBSCH, n = 5, P = 0.2-0.7). Phytohaemagglutinin responses determined fluorocytometrically with induction of CD69 expression were reduced in CD4+ and CD8+ cells following filgrastim administration in 3/3 RA patients tested. Compared with bone marrow as a potential source of CD34+ cells, PBSCH contained 11-fold more T cells (P < 0.0005), 8-fold more B cells (P < 0.0005) and 4-fold more monocytes (P = 0.02). In short-term methylcellulose culture there were no differences in colony counts (CFU-GM, CFU-GEMM, BFU-E) per CD34+ cell from PBSCH from RA patients (n = 11) and healthy donors (n = 10). Long-term culture initiator cells were cultured successfully from cryopreserved PBSCH from RA patients (n = 9). In conclusion, PBSCH from RA patients differed significantly in composition from normal individuals, but in vitro studies support normal stem and progenitor cell function. Changes in T-cell function occur during mobilization in RA patients. This work provides reassurance for the use of PBSCH as haematological rescue and baseline data for clinical trials of graft manipulation strategies in patients with RA.     

Diagnostic and prognostic value of interleukin-6 in malignant non-Hodgkin's lymphomas

Sixty six patients with non-Hodgkin's lymphomas (NHL) were studied, interleukin-6 (IL-6) was revealed in the blood sera of 33 patients. IL-6 was revealed more frequently in patients with high-grade malignant (p < 0.05) than in those with low-grade malignancy. The largest group of IL-6 positive patients included NHL patients with diffuse large B-cell lymphoma and angioimmunoblastic lymphoma. The marked relationship was found between the serum IL-6 levels and the stage of disease: the serum IL-6 level was significantly lower in untreated patients with Stages II and III disease than in those with end-stage (IV) NHL. IL-6 significantly decreased upon remission, comparable with its level before the initiation of treatment. Analysing the association of prognosis of disease with the serum IL-6 showed that in the group of patients with good (The SNLG index < 2) and intermediate (2 < SNLG index < by 2.6) prognosis, the concentration of this cytokine was significantly lower than in those with poor prognosis (SNLG index > 2.6). There was a significant decrease of the total survival rates of NHL with serum IL-6 found. Therefore, IL-6 is a good prognostic marker in NHL and associated with the activity of a malignant process. Additionally, the increased serum IL-6 levels correlated with NK activities positively and with serum IL-4 levels negatively.     

Two-beam fluorescence cross-correlation spectroscopy for simultaneous analysis of positive and negative ions in continuous-flow capillary electrophoresis

Two-beam fluorescence cross-correlation spectroscopy was used for multicomponent electrophoretic analysis of positive and negative ions flowing continuously, and in opposite directions, through a polymer-coated electrophoresis capillary. Cross-correlation analysis of the fluorescence monitored from two spatially offset microscopic detection volumes revealed the magnitude and direction of the electrophoretic flow velocity of each analyte. This enabled resolution of a three-component mixture containing nanomolar concentrations of cationic rhodamine 6G and anionic 5-carboxytetramethylrhodamine (TAMRA) and TAMRA-labeled single-stranded DNA in aqueous buffer. The relative concentrations of each analyte, determined from the cross-correlation analysis, agreed with known values within experimental error. This technique is sensitive to molecular processes occurring on a millisecond time scale and will prove useful for monitoring rapid fluctuations in the magnitude and direction of the electrophoretic flow velocity caused by spontaneous chemical reactions or conformational transformations at thermodynamic equilibrium.