Hepatitis C virus treatment and survival in patients with hepatitis C and human immunodeficiency virus co-infection and baseline anaemia.

The impact of pretreatment anaemia on survival in individuals with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) co-infection is not known. Moreover, HCV treatment is offered less frequently to individuals with anaemia, due to haematological side effects of the treatment regimen. This study aimed to determine the effect of HCV treatment on survival among HCV/HIV co-infected individuals with pretreatment anaemia using the Electronically Retrieved Cohort of HCV-Infected Veterans (ERCHIVES). Individuals with HCV/HIV co-infection were included in current analyses. Participants were considered treated if they were prescribed ≥ 4 weeks of HCV treatment. All-cause mortality data were obtained using record linkage. Survival analyses were performed using Cox proportional hazard models. Among 5000 HCV/HIV co-infected individuals, 1671 (33.4%) had pretreatment anaemia. In a follow-up period of up to 7 years (19,500 person-years), individuals with anaemia had significantly higher mortality rate compared with those without anaemia [144.2 (95% CI: 134.5-154.7) vs 47.5 (44.0-51.2) per 1000 person-years, respectively]. Among individuals with anaemia, HCV treatment was associated with significantly lower mortality rate [66.6 (44.3-100.2) vs 149.6 (139.2-160.5) per 1000 person-years, for treated vs untreated, respectively]. Treatment remained associated with substantial survival benefit after taking into account the effect of multiple comorbidities (hazards ratio: 0.34, 95% CI: 0.21-0.62). These data suggest that HCV/HIV co-infected individuals with pretreatment anaemia have significantly higher mortality compared with those without anaemia. HCV treatment is associated with substantial survival benefit in this group. Additional studies are needed to determine strategies to improve HCV treatment rates among this group.

Genetic pathway to recurrent chromosome translocations in murine lymphoma involves V(D)J recombinase.

Chromosome translocations involving antigen receptor loci are a genetic hallmark of non-Hodgkin's lymphomas in humans. Most commonly, these translocations result in juxtaposition of the immunoglobulin heavy-chain (IgH) locus with one of several cellular proto-oncogenes, leading to deregulated oncogene expression. The V(D)J recombinase, which mediates physiologic rearrangements of antigen receptor genes, may play a mechanistic role in some lymphoma translocations, although evidence is indirect. A high incidence of B-lineage lymphomas has been observed in mice with severe combined immunodeficiency (SCID) and p53-null mutations. We show that these tumors are characteristic of the pro-B-cell stage of development and that they harbor recurrent translocations involving chromosomes 12 and 15. Fluorescence in situ hybridization (FISH) shows retention of IgH sequences on the derivative chromosome 12, implying that breakpoints involve the IgH locus. Pro-B-cell lymphomas were suppressed in SCID p53(-/-) mice by a Rag-2-null mutation, demonstrating that DNA breaks generated during V(D)J recombination are required for oncogenic transformation, and suggesting that t(12;15) arise during attempted IgH rearrangement in pro-B cells. These studies indicate that the oncogenic potential inherent in antigen receptor diversification is controlled in vivo by efficient rejoining of DNA ends generated during V(D)J recombination and an intact cellular response to DNA damage.

Erythropoietin receptors induced by dimethyl sulfoxide exhibit positive cooperativity associated with an amplified biologic response.

Erythropoietin triggers the differentiation of erythrocyte progenitors by binding to receptors on their plasma membrane. We report here that pretreatment of erythropoietin-responsive murine erythroleukemia cells with chemical inducers resulted in a striking increase in erythropoietin-specific hemoglobinization. This amplification of the erythropoietin biologic response was accompanied by the induction of a new population of high-density receptors (approximately 20,000 per cell) exhibiting marked positive cooperativity. Erythropoietin binding to new receptors displayed a convex upward Scatchard plot and a Hill coefficient (nH) of 6.75. Measurement of erythropoietin receptor mRNA demonstrated an initial decrease in receptor transcript followed by an approximately 2- to 3-fold increase after 24-48 hr. This increase in receptor message does not appear to account for the magnitude of the receptor up-regulation by dimethyl sulfoxide. We propose that this positive cooperativity reflects the interaction (clustering) of receptors, presumably through the formation of homooligomers or heterooligomers, and that this receptor interaction may amplify the erythropoietin signal transduction pathway.

Purification and characterization of the erythropoietin-sensitive membrane phosphoprotein, pp43.

We have shown previously that purified human erythropoietin rapidly alters the phosphorylation of an integral erythroid membrane protein, pp43 (Choi, H.-S., Wojchowski, D. M., and Sytkowski, A. J. (1987) J. Biol. Chem. 262, 2933-2936). We have now purified pp43 to apparent homogeneity and have prepared antibodies to it. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretic transfer of membrane proteins to nitrocellulose, the antibodies identified pp43 and a series of higher molecular weight antigenically related proteins, up to 50 kDa, in erythropoietin-responsive Rauscher murine erythroleukemia cells and in normal murine erythroid cells. Examination of purified subcellular fractions confirmed the localization of pp43 and the related proteins to the plasma membrane. Phosphorylation with [gamma-32P]ATP demonstrated that, in contrast to pp43, these higher molecular weight proteins were not phosphorylated. Marked differences in both the abundance of pp43 and related proteins and the degree of erythropoietin-sensitive pp43 phosphorylation were found between the plasma membranes of Rauscher cells and those of "non-responsive" Friend murine erythroleukemia cells. In addition only trace amounts of a 50-kDa antigenically related protein and no phosphorylated pp43 were detected in the plasma membranes of two erythropoietin-insensitive human erythroid cells lines, K562 and HEL. The results suggest that the abundance and degree of phosphorylation of pp43 and the antigenically related proteins is strongly correlated with the erythropoietin responsiveness of the particular erythroid cell types.

Characterization of biologically active, platelet-derived growth factor-like molecules produced by murine erythroid cells in vitro and in vivo.

Platelet-derived growth factor (PDGF) is an important serum regulator of erythropoiesis in vitro. We have now obtained evidence suggesting that PDGF-like molecules may also modulate erythropoiesis in vivo. Western blot analysis of cytoplasmic extracts from Rauscher murine erythroleukemia cells and phenylhydrazine-treated mouse splenic erythroid cells revealed the presence of several PDGF-like proteins. The presence of PDGF-like proteins in the cytoplasm of these two erythroid cell types was confirmed by immunohistochemical staining. Using a serum-free biologic assay, PDGF-like biological activity was found in cell lysates and conditioned medium of both Rauscher cells and phenylhydrazine-treated mouse erythroid cells. Subcellular localization experiments revealed the biological activity to be concentrated in the cytosolic fraction. Using a series of antibodies to hematopoietic growth factors we demonstrated that PDGF-like biological activity was specifically immunoprecipitated by both monoclonal and polyclonal anti-human PDGF antibodies but not by antibodies to burst-promoting activity, granulocyte-macrophage colony-stimulating factor, IL-3, or erythropoietin. Taken together, the data are consistent with the hypothesis that PDGF-like molecules play a role in the regulation of mammalian erythropoiesis in vivo.

Infrared spectrometry.

A brief history of the early work on Fourier spectroscopy at the Johns Hopkins University is given as well as a general description of the techniques of Fourier and Hadamard transform spectroscopy. The techniques of tunable diode laser spectroscopy and the difference frequency technique for IR spectral studies are also briefly described including some of their characteristics.

Spectral measurements of high temperature 13C16O2 and 13C16O18O in the 4.3-microm region.

High resolution (0.007-cm(-1)) spectral measurements of a hot (800 K) CO(2) sample consisting of 88% (13)C(16)O(2), 11% (13)C(16)O(18)O, and 1% various other isotopes were made in the 4.3-microm region using the Air Force Geophysics Laboratory Fourier transform spectrometer. Vibration-rotation constants which predict line positions to better than 0.001 cm(-1) are presented for several bands of these two isotopes.

Spectral measurements of stack effluents using a double-beam interferometer with background suppression.

The emission spectra of the effluents from four selected stacks were measured using a double-beam interferometer to provide real-time background suppression. The double-beam interferometer system, installed in a mobile van, provided the capability for field site measurements and near real-time graphical data display. The advantages of double-beam interferometric background suppression are discussed. Selected spectra were analyzed, and one, from a municipal incinerator, was compared with a FASCODE generated synthetic spectrum.

Background suppression in double-beam interferometry.

An optical background suppression technique is described in which the lower spatial frequencies of a background field are effectively suppressed, thereby enhancing the detectability of localized sources. The technique is particularly applicable for use in image-forming double-beam interferometers in which the individual detector elements are matched to the diffraction-limited resolution of the instrument. The technique uses pairs of optical systems whose modulation transfer functions are suitably matched, and a number of these pairs are described.

Real-time spectral synthesis in Fourier spectroscopy.

A real-time technique to synthesize the spectral distribution from the corresponding interferogram is described. A portable real-time synthesizer has been constructed and test results are presented. Functions with known spectra and an actual interferogram have been used for purposes of evaluation.