Virtual Replicas of Real Places: Experimental Investigations.

As virtual reality (VR) technology becomes cheaper, higher-quality, and more widely available, it is seeing increasing use in a variety of applications including cultural heritage, real estate, and architecture. A common goal for all these applications is a compelling virtual recreation of a real place. Despite this, there has been very little research into how users perceive and experience such replicated spaces. This article reports the results from a series of three user studies investigating this topic. Results include that the scale of the room and large objects in it are most important for users to perceive the room as real and that non-physical behaviors such as objects floating in air are readily noticeable and have a negative effect even when the errors are small in scale.

Immersive Analytics: Theory and Research Agenda.

Advances in a variety of computing fields, including "big data," machine learning, visualization, and augmented/mixed/virtual reality, have combined to give rise to the emerging field of immersive analytics, which investigates how these new technologies support analysis and decision making. Thus far, we feel that immersive analytics research has been somewhat ad hoc, possibly owing to the fact that there is not yet an organizing framework for immersive analytics research. In this paper, we address this lack by proposing a definition for immersive analytics and identifying some general research areas and specific research questions that will be important for the development of this field. We also present three case studies that, while all being examples of what we would consider immersive analytics, present different challenges, and opportunities. These serve to demonstrate the breadth of immersive analytics and illustrate how the framework proposed in this paper applies to practical research.

Age related visual impairment in the elderly.

Visual impairment among the elderly is a major health problem. With advancing age, the normal function of eye tissues decreases and there is an increased incidence of ocular pathology. Demographic studies have shown that age is the best predictor of blindness and visual impairment. The most common causes of age related visual impairment in the elderly are presbyopia, cataracts, age related macular degeneration, primary open angle glaucoma and diabetic retinopathy. Untreated visual impairment leads to physical handicap, increased incidence of fall, depression, social isolation and dependency. Active screening for visual loss in the elderly should be part of the health examination. The elderly should be encouraged to come for formal 1-2 yearly eye assessment for early detection of visual impairment and to treat all associated problems in order to prevent permanent visual loss.

Recognition of cognate transfer RNA by the 30S ribosomal subunit.

Crystal structures of the 30S ribosomal subunit in complex with messenger RNA and cognate transfer RNA in the A site, both in the presence and absence of the antibiotic paromomycin, have been solved at between 3.1 and 3.3 angstroms resolution. Cognate transfer RNA (tRNA) binding induces global domain movements of the 30S subunit and changes in the conformation of the universally conserved and essential bases A1492, A1493, and G530 of 16S RNA. These bases interact intimately with the minor groove of the first two base pairs between the codon and anticodon, thus sensing Watson-Crick base-pairing geometry and discriminating against near-cognate tRNA. The third, or "wobble," position of the codon is free to accommodate certain noncanonical base pairs. By partially inducing these structural changes, paromomycin facilitates binding of near-cognate tRNAs.

Alternative oxidation by isopenicillin N synthase observed by X-ray diffraction.

BACKGROUND: Isopenicillin N synthase (IPNS) catalyses formation of bicyclic isopenicillin N, precursor to all penicillin and cephalosporin antibiotics, from the linear tripeptide delta-(L-alpha-aminoadipoyl)-L-cysteinyl-D-valine. IPNS is a non-haem iron(II)-dependent enzyme which utilises the full oxidising potential of molecular oxygen in catalysing the bicyclisation reaction. The reaction mechanism is believed to involve initial formation of the beta-lactam ring (via a thioaldehyde intermediate) to give an iron(IV)-oxo species, which then mediates closure of the 5-membered thiazolidine ring. RESULTS: Here we report experiments employing time-resolved crystallography to observe turnover of an isosteric substrate analogue designed to intercept the catalytic pathway at an early stage. Reaction in the crystalline enzyme-substrate complex was initiated by the application of high-pressure oxygen, and subsequent flash freezing allowed an oxygenated product to be trapped, bound at the iron centre. A mechanism for formation of the observed thiocarboxylate product is proposed. CONCLUSIONS: In the absence of its natural reaction partner (the N-H proton of the L-cysteinyl-D-valine amide bond), the proposed hydroperoxide intermediate appears to attack the putative thioaldehyde species directly. These results shed light on the events preceding beta-lactam closure in the IPNS reaction cycle, and enhance our understanding of the mechanism for reaction of the enzyme with its natural substrate.

Molecular alignment of proteins in bicellar solutions: quantitative evaluation of effects induced in 2D COSY spectra.

Partial molecular alignment leads to an incomplete averaging of anisotropic magnetic interactions such as magnetic dipole interaction or chemical shift anisotropy. In the present contribution we quantitatively describe and evaluate the effects induced by the addition of magnetically oriented lipid bicelles in homonuclear two-dimensional (2D) NMR correlation (COSY) spectra of proteins. It is shown that 2D COSY experiments allow the measurement of H(N)-H(alpha) residual dipole couplings of positive sign which can be used for structure refinement. In contrast to the double- and triple-resonance experiments previously proposed, these measurements can be carried out even on nonisotope-enriched samples.

Nitric oxide promotes the internalization and passage of viable bacteria through cultured Caco-2 intestinal epithelial cells.

Nitric oxide (NO) may play an important role in the pathophysiology of intestinal barrier disruption. Our purpose was to investigate the effects of NO donors on the internalization and passage of bacteria through cultured intestinal epithelial cells. Human intestinal epithelial cell line Caco-2 cells were grown on microtiter plastic plates. The cells were incubated with Escherichia coli and sodium nitroprusside (SNP) or S-nitroso-N-acetyl-penicillamine (SNAP), as NO donors, at several concentrations. The numbers of viable bacteria internalized into the epithelial cells were measured. Caco-2 cells were also grown to confluency on membranes of bicameral systems. The cells were incubated with E. coli and SNP. The numbers of viable bacteria passed through the epithelial layer were determined. Viability of the bacteria and the intestinal epithelial cells after culture with SNP or SNAP were also determined. Both SNP and SNAP at .1 or 1 mmol/L increased the number of viable bacteria internalized into the enterocytes. Both 1 or 10 mmol/L SNP promoted bacterial passage through the intestinal epithelial layer. However, 10 mmol/L SNP decreased the number of viable Caco-2 cells and failed to increase the bacterial internalization into Caco-2 cells. Incubation of E. coli with SNAP at 10 mmol/L slightly decreased the number of viable bacteria and failed to increase the bacterial internalization into Caco-2 cells. We conclude that NO donors promote both the viable bacterial uptake and passage through the intestinal epithelial layer.

Economics of myocardial perfusion imaging in Europe--the EMPIRE Study.

BACKGROUND: Physicians use myocardial perfusion imaging to a variable extent in patients presenting with possible coronary artery disease. There are few clinical data on the most cost-effective strategy although computer models predict that routine use of myocardial perfusion imaging is cost-effective. OBJECTIVES: To measure the cost-effectiveness of four diagnostic strategies in patients newly presenting with possible coronary artery disease, and to compare cost-effectiveness in centres that routinely use myocardial perfusion imaging with those that do not. METHODS: We have studied 396 patients presenting to eight hospitals for the diagnosis of coronary artery disease. The hospitals were regular users or non-users of myocardial perfusion imaging with one of each in four countries (France, Germany, Italy, United Kingdom). Information was gathered retrospectively on presentation, investigations, complications, and clinical management, and patients were followed-up for 2 years in order to assess outcome. Pre- and post-test probabilities of coronary artery disease were computed for diagnostic tests and each test was also assigned as diagnostic or part of management. Diagnostic strategies defined were: 1: Exercise electrocardiogram/coronary angiography, 2: exercise electrocardiogram/myocardial perfusion imaging/coronary angiography, 3: myocardial perfusion imaging/coronary angiography, 4: coronary angiography. Primary outcome measures were the cost and accuracy of diagnosis, the cost of subsequent management, and clinical outcome. Secondary measures included prognostic power, normal angiography rate, and rate of angiography not followed by revascularization. RESULTS: Mean diagnostic costs per patient were: strategy 1: 490 Pounds, 2: 409 Pounds, 3: 460 Pounds, 4: 1253 Pounds (P < 0.0001). Myocardial perfusion imaging users: 529 Pounds, non-users 667 Pounds (P = 0.006). Mean probability of the presence of coronary artery disease when the final clinical diagnosis was coronary artery disease present were, strategy 1: 0.85, 2: 0.82, 3: 0.97, 4: 1.0 (P < 0.0001), users 0.93, non-users 0.88 (P = 0.02), and when coronary artery disease was absent, 1: 0.26, 2: 0.22, 3: 0.16, 4: 0.0 (P < 0.0001), users 0.21, non-users 0.20 (P = ns). Total 2-year costs (coronary artery disease present/absent) were: strategy 1: 4453 Pounds/710 Pounds, 2: 3842 Pounds/478 Pounds, 3: 3768 Pounds/574 Pounds, 4: 5599 Pounds/1475 Pounds (P < 0.05/0.0001), users: 5563 Pounds/623 Pounds, non-users: 5428 Pounds/916 Pounds (P = ns/0.001). Prognostic power at diagnosis was higher (P < 0.0001) and normal coronary angiography rate lower (P = 0.07) in the scintigraphic centres and strategies. Numbers of soft and hard cardiac events over 2 years and final symptomatic status did not differ between strategy or centre. CONCLUSION: Investigative strategies using myocardial perfusion imaging are cheaper and equally effective when compared with strategies that do not use myocardial perfusion imaging, both for cost of diagnosis and for overall 2 year management costs. Two year patient outcome is the same.

Bone marrow and splenocyte coculture-generated cells enhance allograft survival.

BACKGROUND: Protocols that incorporate donor-specific cell infusions using bone marrow, spleen, or blood transfusion continue to enhance allograft survival and often lead to tolerance in experimental models. Clinical benefits from these modalities have not been as striking, leading to ongoing study in this field. We have explored culture techniques for the in vitro selection and development of cellular effectors capable of enhancing allograft survival. METHODS: Rat bone marrow or spleen cells cultured under a variety of conditions were screened for suppressor function. Bone marrow cells, nonadherent to plastic, cultured for 7 days with granulocyte-macrophage colony-stimulating factor, lipopolysaccharide, and with or without splenocytes were found to contain predominantly myeloid lineage cells and had the ability to suppress phytohemagglutinin or mixed lymphocyte reaction-induced splenocyte proliferation. Standard donor-specific peripheral blood transfusion was compared with cultured donor-specific bone marrow cells, splenocytes, or marrow cells cultured with splenocytes (cocultured) administered intravenously at 1 x 10(7) cells/kg the day before an ACI to Lewis heterotopic heart transplant. Cyclosporine was administered at 10 mg/kg on day -1 and 2.5 mg/kg on days 0-6 relative to transplantation. RESULTS: Mean allograft survival in cyclosporine-treated animals was 8.5 days without and 16.6 days with a donor-specific blood transfusion. Cocultured cells extended allograft survival (39.5 days), whereas bone marrow or splenocytes cultured alone did not. With Percoll gradient separation, two predominant culture subfractions, one with potent suppressor function and another with stimulator function, were identified. Flow cytometric analysis showed mixed populations enriched for macrophages but also including dendritic cells in both subfractions. The suppressive fraction extended allograft survival to 20.8 days and the stimulatory fraction was less effective, yet remixing of both fractions regained the full allograft survival advantage. CONCLUSIONS: In this model, the coculture of bone marrow cells and splenocytes with granulocyte-macrophage colony-stimulating factor and lipopolysaccharide produced functionally divergent subpopulations that synergistically enhanced allograft survival. The development of cellular effectors with enhanced ability to prolong allograft survival using in vitro culture techniques is possible, and provides a new therapeutic option in the use of cell infusion-based therapies.

Induction of endotoxin tolerance in rat bone marrow cells by in vivo infusion of tumor necrosis factor.

OBJECTIVE: To determine in a rat model whether a low-dose infusion of tumor necrosis factor (TNF) affects the production of the inflammatory cytokines TNF and interleukin (IL)-6, the immunosuppressive factor prostaglandin E2 (PGE2), and complement component C3 (C3) by isolated bone marrow-adherent and -nonadherent cells, cultured in the presence of lipopolysaccharide, a component of bacterial endotoxin. DESIGN: Randomized, controlled animal study. SETTING: Research laboratory of a university medical center. SUBJECTS: Sprague-Dawley rats (n = 18), 250 to 275 g. INTERVENTIONS: Animals received a continuous infusion of one of the following three treatments for 4 days: a) TNF in saline containing bovine serum albumin; b) saline containing bovine serum albumin; and c) saline alone. MEASUREMENTS AND MAIN RESULTS: After infusion, isolated bone marrow cells were cultured for 1 day and 3 days, with and without lipopolysaccharide (1 microgram/mL); culture supernatants were assayed for TNF, IL-6, PGE2, and C3. TNF infusion caused a decrease in the in vitro production of TNF, IL-6, and PGE2 by the lipopolysaccharide-stimulated adherent and nonadherent bone marrow cells. This tolerance to lipopolysaccharide stimulation was present after both 1 day and 3 days of culture. TNF infusion caused an increase in C3 production by the nonadherent cells. The production of TNF by adherent cells from saline-infused or bovine serum albumin-infused animals (controls) was greater in 3-day cultures compared with 1-day cultures, whereas the production of IL-6 and PGE2 was less. CONCLUSIONS: These results indicate that TNF infusion caused cells in the bone marrow to be tolerant to lipopolysaccharide stimulation or that TNF infusion programmed the cells to become tolerant to lipopolysaccharide stimulation on differentiation and/or maturation. The results also indicate that bone marrow cells may be regulated by TNF (probably indirectly) at different phases of maturation and/or differentiation with respect to the production of different mediators. Although TNF is considered to be an inflammatory cytokine, at low concentrations it may be an important down-regulator of the inflammatory response.

The radiopharmaceutical industry and European Union regulations.

After a brief historical introduction to Council Directives relating to the manufacture of radiopharmaceuticals the work of the Association of Radiopharmaceuticals Producers - Europe (ARPE) is discussed. ARPE has played a significant role as an officially recognized interlocutor with the EEC, influencing decisions on the registration of radiopharmaceuticals and labelling; this role is reviewed and difficulties identified. The future of radiopharmaceuticals is then considered; it is emphasized that harmonization of national laws by the European Council would represent a first step to enabling radiopharmaceutical manufacturers to access the largest possible market for their products.

The gut as a source of inflammatory cytokines after stimulation with endotoxin.

OBJECTIVE: To find out if endotoxin (LPS) can mediate the production of inflammatory cytokines by enterocytes. DESIGN: Laboratory experiment. SETTING: Teaching hospital and burns unit, USA. MATERIAL: Caco-2 cells (HTB38, human adenocarcinoma, and colon). MAIN OUTCOME MEASURES: Concentrations of tumour necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6) and prostaglandin E2 (PGE2) in cell culture supernatants. RESULTS: LPS significantly increased the production of TNF from 8.9 to 26.4 units/ml in 24 h and this increase persisted at a lower level for 4 days with an increase from 2.3 to 9 units/ml at a cell concentration of 2 x 10(5) cells/ml. There was no increase in TNF production when the cells were cultured at 5 x 10(5) cells ml with LPS. At a concentration of 2 x 10(5) cells/ml, the cells produced small amounts of IL-6 in 24 h or 4 day cultures with or without LPS. At a concentration of 5 x 10(5) cells/ml, LPS significantly increased IL-6 production in 24 h from 142 to 433 units/ml and from 106 to 250 units/ml in 4 days. The amount of IL-6 produced by LPS-stimulated cells was greater at 1 day than at 4 days. There was no significant difference in PGE2 production by the cells under any of the incubation conditions. CONCLUSION: Enterocytes can produce TNF and IL-6, and endotoxin can increase the production of these cytokines by enterocytes. The gut therefore has the potential to become an important source of inflammatory cytokines.

Thermal injury induces the development of inflammatory macrophages from nonadherent bone marrow cells.

The normal course of hematopoiesis is controlled by growth factors and cytokines and, therefore, should be susceptible to alterations induced by systemic mediator release such as that seen following thermal injury. We hypothesized that a brief exposure of developing macrophages to the postthermal injury state would result in functionally altered progeny. We measured the production of inflammatory mediators by rat, bone-marrow macrophage precursors harvested 24 h following a 30% TBSA burn after subsequent maturation in a controlled, in vitro environment. Interleukin (IL)-6, tumor necrosis factor (TNF), and prostaglandin (PG) E2 levels in response to 24 h stimulation with lipopolysaccharide (LPS) were measured following 4 or 8 days of incubation with IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), or both. Flow cytometric analysis showed that bone marrow cells harvested from burn and sham animals cultured in GM-CSF developed principally into macrophages (His48+, R21A6A+, CD11b+. Unstimulated cells produced negligent levels of cytokines and PGE2. Stimulated burn-derived cells released greater amounts of IL-6 and TNF at 4 or 8 days of culture depending on the conditions. Elevated PGE2 release was noted in all GM-CSF containing cultures, with burn-derived cells showing a trend towards reduced prostaglandin release. Detection of mRNA for cytokines after LPS stimulation showed no change in IL-6 or TNF transcripts. A short exposure to the systemic effects of thermal injury preprogramed macrophage progenitor cells with the propensity to develop into inflammatory macrophages, secreting higher levels of TNF and IL-6. This shift towards proinflammatory functions in these cells suggests they could be a source of enhanced inflammatory mediator release at 4 or more days post thermal injury.