Monotherapy versus combination antibiotic therapy for patients with bacteremic Streptococcus pneumoniae community-acquired pneumonia.

The purpose of this study was to examine the impact of antimicrobial monotherapy vs combination therapy on length of stay and mortality for patients with Streptococcus pneumoniae pneumonia. Thirty-nine percent of patients received monotherapy, while 61% received combination therapy. Although there was no significant difference in mortality (OR 1.25, 95% CI = 0.25-6.8), there was a significant increase in length of stay for patients who received combination therapy (p = 0.02). Patients with bacteremic pneumococcal pneumonia treated with empiric combination therapy had no significant difference in mortality; however, they did have increased length of stay after adjusting for severity of illness. Randomized controlled trials are needed to determine what is the optimal empiric antimicrobial regime for patients with community-acquired pneumonia.

Nature, Harmony, and the Kaliyugaya. Global/Local Discourses on the Human-Environment Relationship.

"Living in harmony with nature" has become a root metaphor and an imperative in a postcolonial global discourse on environmental crisis. This article uses an interpretive approach to problematize the concepts of "harmony" and "nature" by juxtaposing global and local discourses on the human-environment relationship. It argues that harmony is a "Western/global" discourse borrowed by Sri Lankan environmentalists that has varying levels of resonance with "local" cultural concepts through a discussion of myths of the Golden Age, nature and morality, the human-deity-nature triad, and the microcosm-macrocosm relationship. The harmony discourse, however, leaves no space for the articulation of an alternative local discourse on the kaliyugaya, which also offers an interpretation of environmental crisis.

Retroviral transduction of quiescent haematopoietic cells using a packaging cell line expressing the membrane-bound form of stem cell factor.

Gene therapy vectors based on murine retroviruses are unable to transduce non-dividing cells. This has proven a particular problem in the haematopoietic system where the target cells of choice, the pluripotent stem cells are quiescent. In an attempt to circumvent this difficulty we have constructed a retroviral producer line that expresses the membrane bound form of human recombinant stem cell factor (SCF) on its cell surface. This should enable the retroviral producers to deliver a growth signal to the target cells simultaneous with their exposure to retrovirus. We tested the ability of these modified producers to transduce a growth factor-starved, SCF-dependent cell line (TF-1) and demon- strated that these cells, though quiescent, can still be successfully transduced. This approach was extended to targeting of umbilical cord blood CD34+ cells, a predominantly quiescent population that normally require the addition of cytokines for efficient transduction. Using the SCF-expressing producer line in the absence of exogenously added cytokines, we observed a marked stimulation in transduction efficiency over that achieved using the parent producer line alone. Colonies derived from these cells arising in semi-solid media were also shown to be positive for expression of a retrovirally encoded reporter gene.

Enhanced retroviral transduction of 5-fluorouracil-resistant human bone marrow (stem) cells using a genetically modified packaging cell line.

Pluripotent hematopoietic stem cells (PHSC) are rare cells capable of multilineage differentiation, long-term reconstituting activity and extensive self-renewal. Such cells are the logical targets for many forms of corrective gene therapy, but are poor targets for retroviral mediated gene transfer owing to their quiescence, as retroviral transduction requires that the target cells be cycling. To try and surmount this problem we have constructed a retroviral producer line that expresses the membrane-bound form of human stem cell factor (SCF) on its cell surface. These cells are capable, therefore, of delivering a growth signal concomitant with recombinant retroviral vector particles. In this report we describe the use of this cell line to transduce a highly quiescent population of cells isolated from adult human bone marrow using the 5-fluorouracil (FU) resistance technique of Berardi et al. Quiescent cells selected using this technique were transduced by cocultivation with retroviral producers expressing surface bound SCF or with the parent cell line that does not. Following coculture, the cells were plated in long-term bone marrow culture for a further 5 weeks, before plating the nonadherent cells in semisolid media. Colonies forming in the semisolid media over the next 14 days were analyzed by polymerase chain reaction for the presence of the retroviral vector genome. Over six experiments, the transduction frequency of the quiescent 5-FU resistant cells using the SCF-expressing producer line averaged about 20%, whereas those transduced using the parent producer line showed evidence of reduced levels or no transduction.

Toxicity of oxysterols to human monocyte-macrophages.

We have investigated the toxicity of the cholesterol oxidation products (oxysterols), 7 alpha-hydroxycholesterol, 7 beta-hydroxycholesterol, 7-ketocholesterol, 25-hydroxycholesterol and 26-hydroxycholesterol to human monocyte-macrophages in vitro. The 7-position derivatives are present in low density lipoprotein (LDL) oxidised with copper (II) sulphate and macrophages, and in extracts of human atherosclerotic lesions, which also contain 26-hydroxycholesterol. We have also assessed 25-hydroxycholesterol for toxicity because it has often been used in studies of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibition and LDL receptor down-regulation. Measurement of radioactivity release from monocyte-macrophages preloaded with tritiated adenine, as a means of assessing cytotoxicity that all the oxysterols showed time- and concentration-dependent toxicity. The cytotoxic potency of 26-hydroxycholesterol was the greatest. The 7-position derivatives also produced marked cell damage, though at higher concentrations than for 26-hydroxycholesterol. Of the oxysterols assessed, the toxicity of 25-hydroxycholesterol was the least. The cytotoxicity of 7 beta-hydroxycholesterol and 26-hydroxycholesterol was also shown using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) dye reduction assay which confirmed that 26-hydroxycholesterol was more toxic than 7 beta-hydroxycholesterol. Incubation of monocyte-macrophages with cholesterol added to the different oxysterols gave varying results. Cholesterol, which was not itself toxic, inhibited the toxicity of 25-hydroxycholesterol and 26-hydroxycholesterol, but the toxicity of the 7-position derivatives was not affected. The possible relevance of these molecules to the death of macrophages seen in atherosclerosis is discussed.