Framework to optimize fixed-length micro-CT systems for propagation-based phase-contrast imaging.

A laboratory X-ray imaging system with a setup that closely resembles commercial micro-CT systems with a fixed source-to-detector distance of ∼90 cm is investigated for single distance propagation-based phase-contrast imaging and computed tomography (CT). The system had a constant source-to-detector distance, and the sample positions were optimized. Initially, a PTFE wire was imaged, both in 2D and 3D, to characterize fringe contrast and spatial resolution for different X-ray source settings and source-to-sample distances. The results were compared to calculated values based on theoretical models and to simulated (wave-optics based) results, with good agreement being found. The optimization of the imaging system is discussed. CT scans of two biological samples, a tissue-engineered esophageal scaffold and a rat heart, were then acquired at the optimum parameters, demonstrating that significant image quality improvements can be obtained with widely available components placed inside fixed-length cabinets through proper optimization of propagation-based phase-contrast.

The effect of a variable focal spot size on the contrast channels retrieved in edge-illumination X-ray phase contrast imaging.

Multi-modal X-ray imaging allows the extraction of phase and dark-field (or "Ultra-small Angle Scatter") images alongside conventional attenuation ones. Recently, scan-based systems using conventional sources that can simultaneously output the above three images on relatively large-size objects have been developed by various groups. One limitation is the need for some degree of spatial coherence, achieved either through the use of microfocal sources, or by placing an absorption grating in front of an extended source. Both these solutions limit the amount of flux available for imaging, with the latter also leading to a more complex setup with additional alignment requirements. Edge-illumination partly overcomes this as it was proven to work with focal spots of up to 100 micron. While high-flux, 100 micron focal spot sources do exist, their comparatively large footprint and high cost can be obstacles to widespread translation. A simple solution consists in placing a single slit in front of a large focal spot source. We used a tunable slit to study the system performance at various effective focal spot sizes, by extracting transmission, phase and dark-field images of the same specimens for a range of slit widths. We show that consistent, repeatable results are obtained for varying X-ray statistics and effective focal spot sizes. As the slit width is increased, the expected reduction in the raw differential phase peaks is observed, compensated for in the retrieval process by a broadened sensitivity function. This leads to the same values being correctly retrieved, but with a slightly larger error bar i.e. a reduction in phase sensitivity. Concurrently, a slight increase in the dark-field signal is also observed.

Air filter materials, outdoor ozone and building-related symptoms in the BASE study.

UNLABELLED: Used ventilation air filters have been shown to reduce indoor environmental quality and worker performance and increase symptoms, with effects stronger after reaction of filters with ozone. We analyzed data from the US EPA Building Assessment Survey and Evaluation (BASE) study to determine if ozone and specific filter media have interactive effects on building-related symptoms (BRS). We analyzed a subset of 34 buildings from the BASE study of 100 US office buildings to determine the separate and joint associations of filter medium [polyester/synthetic (PS) or fiberglass (FG)] and outdoor ozone concentration (above/below the median, 67.6 microg/m(3)) with BRS. Using logistic regression models and general estimating equations, we estimated odds ratios (ORs) and 95% confidence intervals for the association of filter medium, ozone, and filter medium x ozone with BRS. Relative to FG + low ozone, PS alone or high ozone alone, were each significantly (P < 0.05) associated only with fatigue/difficulty concentrating (ORs = 1.93 and 1.54, respectively). However, joint exposure to both PS + high ozone, relative to FG + low ozone, had significant associations with lower and upper respiratory, cough, eye, fatigue, and headache BRS (ORs ranged from 2.26 to 5.90). Joint ORs for PS + high ozone for lower and upper respiratory and headache BRS were much greater than multiplicative, with interaction P-values <0.10. Attributable risk proportion (ARP) estimates indicate that removing both risk factors might, given certain assumptions, reduce BRS by 26-62%. These findings suggest possible adverse health consequences from chemical interactions between outdoor ozone and PS filters in buildings. Results need confirmation before recommending changes in building operation. However, if additional research confirms causal relationships, ARP estimates indicate that appropriate filter selection may substantially reduce BRS in buildings, especially in high-ozone areas. PRACTICAL IMPLICATIONS: The results indicate that a better understanding of how filters interact with their environment is needed. While the mechanism is unknown and these findings need to be replicated, they indicate that the joint risk of BRS from polyester/synthetic filters and outdoor ozone above 67.6 microg/m(3) is much greater than the risk from each alone. These findings suggest potential reductions in BRS from appropriate selection of ventilation filter media or implementing strategies to reduce ozone entrained in building ventilation systems. If the relationships were found to be causal, filter replacement and ozone abatement should be undertaken.

Outdoor ozone and building-related symptoms in the BASE study.

UNLABELLED: Reactions between ozone and indoor contaminants may influence human health and indoor air quality. The U.S. EPA Building Assessment Survey and Evaluation (BASE) study data were analyzed for associations between ambient ozone concentrations and building-related symptom (BRS) prevalence. Multiple logistic regression (MLR) models, adjusted for personal, workplace, and environmental variables, revealed positive relationships (P < 0.05) between ambient ozone concentrations and upper respiratory (UR), dry eyes, neurological and headache BRS (odds ratios ranged from 1.03 to 1.04 per 10 mug/m(3) increase in ambient ozone concentrations). Other BRS had marginally significant relationships with ambient ozone (P < 0.10). A linear dose-response in UR symptoms was observed with increasing ambient ozone (P = 0.03); most other symptoms showed similar but not statistically significant trends. Ambient ozone correlated with indoor concentrations of some aldehydes, a pattern suggesting the occurrence of indoor ozone chemistry. Coupled with the MLR ambient ozone-BRS analysis, this correlation is consistent with the hypothesis that ozone-initiated indoor reactions play an important role in indoor air quality and building occupant health. Replication with increased statistical power and with longitudinal data is needed. If the observed associations are confirmed as causal, ventilation system ozone removal technologies could reduce UR BRS prevalence when higher ambient ozone levels are present. PRACTICAL IMPLICATIONS: This paper provides strong statistical evidence that supports (but does not prove) the hypothesis that ozone entrained into buildings from the outdoor air is involved in increasing the frequency that occupants experience and a range of upper and lower respiratory, mucosal and neurological symptoms by as much as a factor of 2 when ambient ozone levels increase from those found in low-ozone regions to those typical of high-ozone regions. Although replication is needed, the implication is that reducing the amount of ozone entrained into building ventilation systems, either by ambient pollution reduction or engineered gas-phase filtration, may substantially reduce the prevalence of these symptoms experienced by occupants.

Soil-based treatment of partially treated liquid swine manure.

A soil-column system was tested for the removal of soluble organics and nutrients from partially treated liquid swine manure. The liquid manure was applied to the 900 mm deep (300 mm of local topsoil and 600 mm of local subsoil) soil columns continuously for an eight-week period, and leachate as well as soil samples were analysed. An effective liquid manure application rate of 17 mm d(-1) was determined based on a preliminary liquid manure soil-based treatment experiment. It was found that more than 90% of five-day biochemical oxygen demand, chemical oxygen demand, total Kjeldahl and ammonia nitrogen, and total phosphorus could be effectively removed from the liquid manure by the soil system. Nitrogen contents accumulated in the soil matrix mostly within the 0 to 300 mm depth, while no significant increase was observed in sub soils. Soil analyses indicated the occurrence of nitrification and denitrification in the soil columns. Nitrogen balance showed that about 42% of the applied nitrogen was lost from the system during the liquid manure soil-based treatment experiment, suggesting the emission of ammonia and other gaseous nitrogen generated through nitrification and denitrification. The leachate of the soil treatment system was used to irrigate Bermuda grass. No negative effect of leachate was observed on the plant growth.

Development of an integrated enzymatic treatment system for phenolic waste streams.

An integrated enzymatic treatment system, which includes Coprinus cinereus peroxidase (CIP) production, processing, and usage in batch or plug flow reactors, is being developed to remove phenolic compounds from the aqueous waste streams. CIP production at bench scale yielded a maximum growth medium activity of approximately 60 U CIP ml(-1). A CIP enzyme solution was prepared for use in treatment by successive filtration steps. This yielded a 4.5-fold increase in enzyme activity, with 87% enzyme activity recovery, and 83% reduction in the solution's Chemical Oxygen Demand. The purity of CIP was observed to have no effect on the ability of the enzyme to remove phenol from the aqueous solutions within the range of enzyme solution purities tested. Contrary to observations reported for phenol removal from buffered solutions, the addition of polyethylene glycol to non-buffered reaction solutions had no positive effect on the phenol removal accomplished at pH 7 in these experiments. The efficiency of enzyme use in a plug flow reactor was improved by step additions of CIP and H2O2.

Acute hepatitis C virus seroconversion in a Scottish blood donor: HCV antigen is not comparable with HCV nucleic acid amplification technology screening.

BACKGROUND AND OBJECTIVES: This study was conducted to analyse the usefulness of hepatitis C virus (HCV) core antigen tests for the confirmation of HCV infection in a donor presenting as nucleic acid amplification technology (NAT) positive but negative for antibodies to HCV (anti-HCV). MATERIALS AND METHODS: Blood donations were screened, in parallel, for anti-HCV using the Abbott PRISM HCV Chemiluminescent immunoassay (ChLIA) and an 'in-house' HCV NAT (pools of up to 95 donations). An HCV NAT-positive antibody-negative donor was identified. Twelve follow-up samples were obtained and tested with various HCV antigen (including the recently marketed Trak-C second-generation assay) and HCV antibody assays. RESULTS: The single HCV NAT-positive, antibody-negative donation was identified from 1 117 681 donations screened in the 4-year period, July 1999 to June 2003. The index donation was positive by Ortho HCV core antigen enzyme immunoassay (EIA) and Ortho Trak-C (second-generation HCV core antigen EIA). An archive sample, taken 127 days prior to the index donation, was negative for all HCV markers. Subsequent samples demonstrated a loss of reactivity in the Ortho HCV core antigen EIA and reduced activity in the Ortho Trak-C until day 69. Immunoblot (Ortho RIBA-3) and HCV PRISM became positive on day 62, whilst Ortho HCV ELISA was not positive until day 132 or Biorad HCV ELISA until day 160. An alternative immunoblot (Innogenetics Innolia III) was positive from day 55. RNA levels fluctuated considerably during the follow-up period, being completely undetectable by routine screening methods at the time-point around seroconversion; subsequently, antibody was detected using all assays investigated. CONCLUSIONS: This HCV-converting blood donor provided a unique panel of samples for using to assess current (and future) HCV assay systems. The overall test results led to the conclusion that individual HCV antigen testing should not be considered as equivalent to HCV NAT minipool screening. Trak-C antigen testing may be considered as a suitable confirmatory assay for isolated HCV NAT reactivity.

Hepatitis B vaccinees may be mistaken for confirmed hepatitis B surface antigen-positive blood donors.

BACKGROUND AND OBJECTIVES: Hepatitis B surface antigen (HBsAg) test sensitivities have gradually increased, and neutralizable weak HBsAg-positive donations, with no other hepatitis B virus (HBV) markers, have occasionally been found in our donor population. On investigation, these donors have admitted to receiving hepatitis B vaccine up to 5 days previously. A study was therefore initiated to monitor HBsAg reactivity amongst volunteers after receiving their first dose of hepatitis B vaccine. MATERIALS AND METHODS: Eight volunteers were tested using three HBsAg assays (Abbott Auszyme, Ortho HBsAg-3 and Abbott/Murex GE34/36) on days 0, 3, 5, 7 and 10 after administration of hepatitis B vaccine. RESULTS: Two HBsAg tests (Abbott Auszyme and Ortho HBsAg-3) did not detect HBsAg reactivity amongst the volunteers, although the Abbott Auszyme test results reached 70-80% of the manufacturer's cut-off at day 3 in two volunteers. The most recently launched assay (Abbott/Murex GE 34/36) detected seven (87%) of the eight volunteers as HBsAg reactive on day 3, and two (25%) volunteers were still reactive on day 5. CONCLUSION: The Abbott/Murex GE 34/36 assay demonstrated HBsAg reactivity in most volunteers on day 3 and in some on day 5 after vaccination. It is therefore recommended that individuals who have recently been vaccinated with hepatitis B be deferred from blood donation for at least 7 days.

Screening of Coprinus species for the production of extracellular peroxidase and evaluation of the enzyme for the treatment of aqueous phenol.

The production of extracellular peroxidase by twenty-five strains of Coprinus species was investigated for the purpose of its application to the removal of phenolic and other aromatic compounds from industrial waste streams. After initial screening experiments, the production of peroxidase by three superior strains of C cinererus UAMH 4103, UAMH 7907 and IFO 30116 was monitored over a 15-day period. Peroxidase activity was detected after 3 days of growth and had reached itspeak another 6 days later. The peroxidase activity appeared to increase with a corresponding depletion of glucose concentration and rapidly declined immediately after the exhaustion of glucose. The effectiveness of the cultivated C. cinereus peroxidase (CIP) for the removal of aqueous phenol was evaluated in the presence and in the absence of additives including polyethylene glycol (PEG) and chitosan, and compared with those of purified horseradish peroxidase (HRP) and Arthromyces ramosus peroxidase (ARP). The addition of PEG and chitosan enhanced the efficiency of phenol transformation catalyzed by CIP by the factor of 1.5 and 1.3, respectively. Although the efficiency of phenol transformation was higher with CIP than those with purified HRP and ARP in the absence of addtives, its superiority diminished in the presence of PEG. This suggests that the by-products of fungal culture in the crude CIP solution, presumably polycarbohydrates and proteins, have protective effects on the enzyme against inactivation during catalytic transformation of phenol, and the addition of PEG provides small effects on further protection.

The effects of iron deficiency on lymphocyte cytokine production and activation: preservation of hepatic iron but not at all cost.

Worldwide, over 40% of children have iron deficiency anaemia, frequently associated with infections. Certain cytokines are involved in both immune activation/response to infection and iron transport/metabolism. We therefore assessed the relations among iron deficiency, cytokine production and lymphocyte activation markers in 142 hospitalized Malawian children. We examined peripheral blood lymphocyte antigens/cytokine production using four- colour flow cytometry and serum transferrin receptor (TfR) levels, an inverse measure of iron status unaffected by acute illness or infection, with an enzyme-linked immunosorbent assay. Wilcoxon rank sum tests and logistic regression analyses (LRA) were performed. Iron deficiency (TfR > or = 10 microg/ml) versus TfR < 10 microg/ml, was associated with higher percentages of lymphocytes producing: (a) induced or spontaneous IL-6 (medians: induced, 15.9% for iron-deficient children versus 8.8% for iron-replete children, P = 0.002; spontaneous, 24.4% versus 13.0%, P < 0.001) and (b) induced IFN-gamma (medians:18.4% versus 12.4%, P = 0.006). The percentages of CD8(+) T cells spontaneously producing IL-6 and of all lymphocytes producing induced TNF-alpha and IFN-gamma in the same cell had the strongest relationships to iron deficiency (b = + 0.0211, P = 0.005 and b = + 0.1158, P = 0.012, respectively, LRA) and were also positively related to the co-expression of the T cell activation markers HLA DR and CD38. Severe iron deficiency (TfR > or = 30 microg/ml) was associated with the percentage of lymphocytes producing induced IL-4 (medians: 0.5% versus 1.6%, P < 0.010). The cytokine patterns associated with iron deficiency in our study would preserve iron stores but also preferentially retain the activation capabilities of T cells, albeit not necessarily other immune cells, until a critical level of iron depletion is reached.

CD8(+) T cells express a T-helper 1--like phenotype after burn injury.

BACKGROUND: Previous studies suggest that CD8(+) T cells are immunosuppressive after burn injury, but recent reports indicate that CD8(+) T cells have several functions similar to CD4(+) T cells, including the secretion of cytokines. This study uses HY male antigen in transgenic HY female mice to determine the antigen-specific response of activated CD8(+) T cells after burn injury. METHODS: HY TCR transgenic female mice underwent burn or sham injury. Seventy-two hours after the burn, splenocytes were stimulated with 20 micromol/L HY peptide for 16, 48, and 64 hours; cellular proliferation, intracellular interferon-gamma and interleukin-2, and apoptosis were measured. RESULTS: Burn injury significantly impaired proliferation to HY antigen (P < or =.05). Activated CD8(+) T cells from burned mice showed increased intracellular interferon-gamma and interleukin-2 16 hours after stimulation compared with sham (P < or =.05) and at no time was less than control mice. The percent of CD8(+) T cells decreased with the time of stimulation but was not due to apoptosis by Annexin V staining. CONCLUSIONS: Activated CD8(+) T cells express a T(h1)-like phenotype after burn injury. This provides evidence that CD8(+) T cells are not simply suppressive and that is consistent with data that CD4(+) T cells are primed for a T(h1) response after burn injury.

Cytokines and malaria parasitemia.

The balance between pro- and antiinflammatory cytokines may be important in malaria presentation and outcome. Malaria tends to be more severe in children than in adults, presumably because partial immunity develops with age. However, the full nature of, and age-related differences in, anti-malarial immunity are unknown. We compared: (1) serum and cell-specific cytokines of patients with acute malaria to those of patients with other acute illnesses and to those of healthy adults and (2) the cytokine responses of parasitemic children and parasitemic adults. Flow cytometry was done on the peripheral blood mononuclear cells of 148 hospitalized children, 161 febrile hospitalized adults, and 20 healthy adults in Malawi, Africa, a malaria-endemic country. Serum cytokines were also assessed for 80 of these patients. Thirty-eight participants were parasitemic with Plasmodium falciparum. Serum interleukin (IL)-10 (an antiinflammatory, immunoregulatory, and type 2 cytokine) levels were higher in malaria patients than in other patients (medians 502 pg/mL vs 16 pg/mL, P = 0.002), and the percentages of various lymphocyte populations making IL-6 (a proinflammatory, type 2 cytokine regulating iron distribution) were lower in malaria patients than in other patients (e.g., for spontaneous production by children's CD8(+) T cells: medians 1.4% vs 33.1%, P = 0.004). For adult patients, the percentages of lymphocytes spontaneously making IL-4 (a type 2 cytokine) were significantly lower in those with malaria than in those without malaria (medians 0.9% vs 2.1%, P = 0.005). The percentages of monocytes spontaneously making IL-8 (a chemotactic, proinflammatory chemokine) were higher in parasitemic children than in parasitemic adults (medians 5.8% vs 1.7%, P = 0.003). A number of cellular proinflammatory, type 1 parameters were significantly higher in all children (with or without malaria) than in all adults; these included the percentages of various lymphocyte populations making IL-6, both IL-6 and interferon-gamma, or IL-8. These data support the importance of IL-10 in malaria parasitemia. Given the lack of an IL-4 (type 2) response, IL-10's primary role may be immunoregulatory rather than type 2 in nature. In this study, the immune response to malaria was more proinflammatory in children than in adults. This difference, if corroborated by other studies, could be related to malaria's greater severity in children.

HTLV antibody screening using mini-pools.

At the present time, the UK blood transfusion services do not screen blood donations for anti-HTLV. This presentation describes a pilot study to ascertain the feasibility of HTLV antibody screening using mini-pools and also provides an estimate of HTLV prevalence within our donor population in Scotland and Northern Ireland. The Abbott/Murex HTLV I/II GE80/81 ELISA was selected for the trial. Thirty confirmed HTLV positive library samples were tested at various dilutions and five were shown to be nonreactive at a dilution of 1:100. Residues of mini-pools (of up to 95 individual donations) prepared for HCV NAT testing were tested with the Abbott/Murex GE80/81 assay. Of 6666 mini-pools (equivalent to 570 609 donations) tested, six were repeatedly reactive. All six mini-pools were confirmed HTLV antibody positive by line immunoassay. Four were confirmed to be HTLV-I positive, one HTLV-II positive and one HTLV positive (unable to type). Dilutions (1:100) of the five HTLV "nonreactive" positive samples were included in each test plate and used to determine a grey-zone cut-off. Using this grey-zone system an additional six (0.09%) mini-pool samples gave repeatedly reactive grey-zone results, none of which were confirmed. The minimum Scottish/Irish HTLV donor prevalence was shown to be 1:95 000.

Risk-resistance adaptation model for caregivers and their children with sickle cell syndromes.

This investigation examined the risk-resistance adaptation model for children with sickle cell disease and their primary caregivers. Participants were 55 children, ranging in age from 5 to 16 years with a mean age of 9 years 2 months, diagnosed with sickle cell disease and their primary caregivers, recruited from a university medical center. Measures included adjustment (i.e. primary caregiver and child adjustment), risk factors (i.e. disease and disability, functional independence, and psychosocial stressors), resistance factors (i.e. intrapersonal health locus of control, social-ecological), and stress processing (coping). Primary caregivers' adjustment was associated with developmental coping, changeR2 = .08, and child adaptation was associated with an internal health locus of control, changeR2 = .22. An indirect effect of primary caregivers' coping on child adjustment was found through influence on primary caregivers' adjustment, changeR2 = .11. The findings support research among other chronically ill populations that suggests an association between coping and disease adjustment. The results were interpreted to support the use of theoretically driven models in predicting the adaptation of children with chronic illness and adjustment in their caregivers.

Natural T, gammadelta, and NK cells in mycobacterial, Salmonella, and human immunodeficiency virus infections.

NK cells, gammadelta T cell antigen receptor chain-positive cells, and CD3(+)CD16/56(+) (natural T [NT]) cells are involved in innate immunity and immunoregulation; however, their role in clinical infection is not well defined. Cytofluorometric analysis was used to examine peripheral blood from bacteremic, nonbacteremic, and healthy human immunodeficiency virus (HIV)-positive and -negative persons in Malawi, Africa. Mycobacteremia was associated with a higher proportion of CD3(+)CD8(-) gammadelta cells (median, 16.6% vs. 0.7% for all other cells; P<.001), and Salmonella bacteremia was associated with a higher proportion of NT cells (4.3% vs. 2.2%; P=. 002). HIV plasma RNA levels were weakly positively correlated with NT cells (rs=.39; P=.002), NK cells (rs=.38; P=.003), and gammadelta cells (rs=.43; P<.001). Compared with patients who survived, patients who died had a higher percentage of NT cells (3.7% vs. 1. 9%; P=.017) and a higher percentage of NT cells that spontaneously produced interferon-gamma (2.4% vs. 1.2%; P=.035). The data support the clinical relevance of gammadelta and NT cells in mycobacterial, Salmonella, and HIV infections and of NT cells in mortality.

Model development for horseradish peroxidase catalyzed removal of aqueous phenol.

Once activated by hydrogen peroxide, horseradish peroxidase (HRP) catalyzes the oxidation of aqueous aromatic compounds to produce high molecular weight polymers of low solubility. A pseudo steady-state kinetic model of the HRP-hydrogen peroxide-aromatic compound system was modified to incorporate enzyme inactivation mechanisms in order to improve its predictive ability. The kinetic constants of the model were calibrated using a series of experimental data sets. The model's ability to predict the time-dependent removal of phenol within the range of 0.5-6 mM from a batch reactor was validated. The model accounts for permanent losses of enzyme activity through inactivation by free radicals as well as interaction with end-product polymers as they form.

Practical application of the PAR index: an illustrative comparison of the outcome of treatment using two fixed appliance techniques.

A retrospective assessment of treatment outcome in a group of 82 orthodontic fixed appliance cases was carried out using the Peer Assessment Rating Index (PAR) in order to explore the usefulness of the PAR index as a means of differentiating the change associated with treatment. Two different fixed appliance techniques, the pre-adjusted Edgewise and the Begg appliance had been used to treat these cases, and all had been under the care of one Consultant Orthodontist. The mean percentage reduction in PAR for the group as a whole was 74 per cent. Comparison of the two different appliance types found that the pre-adjusted Edgewise group achieved a significantly greater reduction in PAR score (81 per cent), than the Begg group (65 per cent). Cases with a low PAR score prior to treatment tended to fare more poorly in terms of percentage reduction and this was more marked for those cases treated with the Begg appliance. Although the PAR index has a high degree of reproducibility, it was found that even the small error present can lead to problems of interpretation if the nomogram categories are used as a method of comparison. Some potential problems in undertaking studies such as this using the PAR index to assess treatment outcome are discussed.