Absorption cross sections of the ClO dimer

The absorption cross sections of the ClO dimer, ClOOCl, are important to the photochemistry of ozone depletion in the Antarctic. In this work, new measurements were made of the dimer cross sections at 195 K. the results yield somewhat lower values in the long wavelength region, compared to those currently recommended in the NASA data evaluation (JPL 94-26). The corresponding solar photodissociation rates in the Antarctic are reduced by about 40%

International Geomagnetic Reference Field: the thirteenth generation

In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group (V-MOD) adopted the thirteenth generation of the International Geomagnetic Reference Field (IGRF). This IGRF updates the previous generation with a definitive main field model for epoch 2015.0, a main field model for epoch 2020.0, and a predictive linear secular variation for 2020.0 to 2025.0. This letter provides the equations defining the IGRF, the spherical harmonic coefficients for this thirteenth generation model, maps of magnetic declination, inclination and total field intensity for the epoch 2020.0, and maps of their predicted rate of change for the 2020.0 to 2025.0 time period

Use of reverse-transcriptase-based HIV-1 viral load assessment to confirm low viral loads in newly diagnosed patients in Switzerland

BACKGROUND: Treatment-naïve patients newly diagnosed with HIV occasionally present with low viral RNA of ≤1'000 copies/ml, raising concerns about viral load underestimation. Because falsely low or undetectable viral loads might lead to inadvertent virus transmission or treatment delays, confirmation of such cases by a sequence-independent viral load test is recommended in Switzerland. METHODS: HIV-1 RNA ≤1'000 cp/ml by Roche's or Abbott's tests in patients newly diagnosed from 2010 to 2012 in Switzerland were subjected to viral load testing by the product-enhanced-reverse transcriptase (PERT) assay. These investigations were complemented with repeat and/or alternative viral RNA measurements. RESULTS: HIV-1 RNA ≤1'000 cp/ml was observed in 71 of 1814 newly diagnosed patients. The PERT assay suggested clinically relevant viral load underestimation in 7 of 32 cases that could be investigated. In four patients, the PERT viral load was 10-1'000-fold higher; this was confirmed by alternative HIV-1 RNA tests. Six of the 7 underestimates had been obtained with meanwhile outdated versions of Roche's HIV-1 RNA test. In the seventh patient, follow-up revealed similar results for RNA and PERT based viral loads. CONCLUSION: PERT assay revealed occasional severe viral load underestimation by versions of HIV-1 RNA tests meanwhile outdated. Underestimation by contemporary tests appears rare, however

Detection of Ehrlichia phagocytophila DNA in Ixodes ricinus ticks from areas in Switzerland where tick-borne fever is endemic

A total of 1,523 adult Ixodes ricinus ticks were collected from regions where bovine ehrlichiosis is endemic and were examined for Ehrlichia phagocytophila via PCR. Of the ticks from cattle with ehrlichiosis, the ticks from healthy cattle, and the free-living ticks, 26.5% (18 of 68), 4.4% (35 of 802), and 0.8% (5 of 653), respectively, were positive

Resolution of plasma sample mix-ups through comparison of patient antibody patterns to E. coli

Background: Accidental sample mix-ups and the need for their swift resolution is a challenge faced by every analytical laboratory. To this end, we developed a simple immunoblot-based method, making use of a patient's characteristic plasma antibody profile to Escherichia coli (E. coli) proteins. Methods: Nitrocellulose strips of size-separated proteins from E. coli whole-cell lysates were incubated with patient plasma and visualised with an enzyme-coupled secondary antibody and substrate. Plasma samples of 20 random patients as well as five longitudinal samples of three patients were analysed for antibody band patterns, to evaluate uniqueness and consistency over time, respectively. For sample mix-ups, antibody band patterns of questionable samples were compared with samples of known identity. Results: Comparison of anti-E. coli antibody patterns of 20 randompatients showed a unique antibody profile for each patient. Antibody profiles remained consistent over time, as shown for three patients over several years. Three example cases demonstrate the use of this methodology in mis-labelling or -pipetting incidences. Conclusion: Our simple method for resolving plasma sample mix-ups between non-related individuals can be performed with basic laboratory equipment and thus can easily be adopted by analytical laboratories

Detection of reverse transcriptase activity in human melanoma cell lines and identification of a murine leukemia virus contaminant.

BACKGROUND: Stimulated by earlier reports on the presence of retroviruses in mouse and hamster melanoma cell lines, we addressed the question as to whether human melanoma cell lines might also harbour a retrovirus. METHODS AND RESULTS: The melanoma cell lines SK-MEL-25, SK-MEL-28, MEL-JUSO, MML-I, MeWo, A-375, Colo-38, BS-780 were confirmed to be human by human leucocyte antigen (HLA) typing, and supernatants were tested by the product-enhanced reverse transcriptase (PERT) assay for reverse transcriptase (RT) activity. Cell lines SK-MEL-25, SK-MEL-28, MEL-JUSO and MML-I were positive, whereas cell lines MeWo, A-375, Colo-38 and BS-780 were negative. The RT activity peaked at a buoyant density in sucrose typical for retroviruses. From this peak fraction an R-U5 sequence indistinguishable from murine leukemia virus (MLV) was identified by particle-associated retrovirus RNA amplification (PARRA). Semiquantitative MLV-specific RNA-PCR demonstrated colocalization of the MLV-like RNA and RT activity on the sucrose gradient of SK-Mel-25. MLV RNA and DNA were also detectable in culture supernatants of SK-MEL-28, MEL-JUSO and MML-I, but not of MeWo, A-375, Colo-38 and BS-780 by semiquantitative polymerase chain reaction (PCR). Sequence comparison revealed highest homology with the RET sequence previously identified in mouse myeloma SP2/0-AG14 cells. Taken together, our data strongly suggest that certain human melanoma cell lines are productively infected by a MLV which was probably introduced during tumour passage in mice or by laboratory contamination many years ago and subsequently spread to other lines. CONCLUSION: We recommend mandatory testing of melanoma and other human cell lines for contamination with infectious MLV or other animal retroviruses, similar to mycoplasma screening, in order to avoid artificial experimental data

Molecular cloning and expression of feline interleukin-16

Human IL-16 (hIL-16) is a homotetrameric cytokine with chemotactic properties towards cells expressing the CD4 receptor. This chemotactic cytokine plays an important role in attracting cells of the immune system to the site where CD8+ T-cells were activated for example by a foreign antigen. In addition to the chemotactic activity, hIL-16 also induces expression of IL-2 receptor, increasing the responsiveness to IL-2 and therefore implying a role for specific expansion of the CD4+ T-cell population in an area of induced inflammation. In this report we describe the cloning, sequencing and the expression of feline IL-16 (fIL-16). At the nucleotide level, fIL-16 shows 84.6 and 84.5%, on the amino acid level 93 and 91.5% identity to the human and African green monkey (agm) IL-16, respectively

Quantitative real-time PCR for detection of members of the Ehrlichia phagocytophila genogroup in host animals and Ixodes ricinus ticks

A TaqMan PCR was established for identification and quantitation of members of the Ehrlichia phagocytophila group in experimentally infected cows and in Ixodes ricinus ticks. The TaqMan PCR identified a 106-bp section of the 16S rRNA gene by use of a specific fluorogenic probe and two primers. This technique was specific for members of the E. phagocytophila group, which include E. phagocytophila, Ehrlichia equi, and the agent of human granulocytic ehrlichiosis. The TaqMan system identified 10 copies of a cloned section of the 16S rRNA gene of E. phagocytophila. The sensitivity and specificity of the TaqMan PCR were similar to those of conventional nested PCR. The numbers of ehrlichiae in leukocytes of the two cows experimentally infected with E. phagocytophila were measured daily by TaqMan PCR and had a course similar to that of the percentages of infected leukocytes determined daily by light microscopy. The prevalence of infected free-living ticks, which were collected from areas where bovine ehrlichiosis is endemic and from regions with sporadic occurrences of granulocytic ehrlichiosis in dogs and horses, was identical as determined by nested PCR and TaqMan PCR