Estimating arsenic biotransfer factors from feed to chicken: a viable approach to animal feed risk assessment

Reliable biotransfer factor (BTF) data are critical for animal-feed studies in human risk assessment. A wide range of BTF values have been reported (0.0015-0.83 d/kg), expressed as the ratio of total arsenic (tAs) concentration (µg/kg) in chicken to daily intake rate (µg/d) of tAs in feed (tAs/tAs). Data on inorganic As (iAs) for chicken meat and tAs concentrations for feed were obtained from our related study. Using the linear regression technique developed in this study, we estimated the BTF as 0.016 d/kg, as iAs/tAs (R² > 0.7702) and 0.55 d/kg as tAs/tAs (R² =  0.9743) for whole chicken meat. From a mass-balance perspective, we suggest that tAs be used as the denominator for the BTF unit. To illustrate our feed-risk assessment method, we analyzed commercial feeds for tAs concentration (n = 79). Consumption data for the general population (n = 2479) were obtained from a Taiwanese total diet study. Bivariate Monte Carlo simulations (n = 10,000) showed that the 95^th percentile (P95) of estimated daily intake (EDI) was 0.002 µg/kg body weight (bw)/d as iAs (< the benchmark dose lower limit of 3.0 µg/kg bw/d). Our results thus show that the commercial chicken feeds assessed in this study are of low health concern for the general Taiwanese population. We discuss the factors that may have affected the assessment, such as the type of animals investigated, type of feeds, feed tested, type of chemical species used for BTF estimation and statistical approach.

Human health risk simulation and assessment of heavy metal contamination in a river affected by industrial activities

The human health risks caused by heavy metal contamination (As, Cd, Cr, Cu, Hg, Pb, Ni, and Zn) in the surface water of the Houjing River, the most contaminated river in southern Taiwan, were assessed in this study. Firstly, heavy metal contamination was evaluated by the contamination factors (CF) and the metal indexes (MI). Secondly, the human health risks due to heavy metal contamination were simulated using the Adaptive Risk Assessments Modeling System (ARAMS) through three scenarios; fish ingestion, dermal water contact, and incidental water ingestion during swimming. The hazard quotient (HQ) and the hazard index (HI) were used to evaluate non-carcinogenic risks, while carcinogenic risks were estimated by the lifetime cancer incidence risk index (CR) and the cumulative cancer risk (CCR). The results showed that the synergistic contamination of heavy metals in the surface water was severe (MI = 12.4), with the highest contribution from Cu, Ni, and Pb. Copper had the highest non-carcinogenic risk at the "adverse effect" level, while Ni and Cr had the highest carcinogenic risk at an "unacceptable" level. In addition, the cumulative risks of fish ingestion (HI_FI = 6.75 and CCR_FI = 1.25E-03) were significantly higher than those of the swimming scenarios (HI_(DC + WI) = 1.94E-03 and CCR_(DC + WI) = 9.32E-08). The results from this study will be beneficial for immediate and future contamination control measures and human health management plans for this study area. This study has also demonstrated the effectiveness of using ARAMS in human health risk assessment.

Dietary exposure assessment of methylmercury and polyunsaturated fatty acids in saltwater fish and processed foods among Taiwanese women of child-bearing age and children: A novel core food-matching approach

Saltwater fish is rich in health-promoting polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Excessive fish intake may also cause health hazards due to methylmercury (MeHg). A novel dose estimation method was proposed in this study to improve the quality of food matching by considering the usage ratio of cooking and processing methods in sampling design. In total, 39 table-ready samples were specified according to 2-3 common cooking methods, and MeHg and total mercury (THg) were analyzed. The results showed that mercury was detected in 20 samples (LOD = 0.01 μg/g). High MeHg samples included fried-Spanish mackerel (1.23 μg/g), non-cooked shredded swordfish (0.325 μg/g), pan-fried Spanish mackerel (0.248 μg/g), and non-cooked shredded salmon (0.208 μg/g). Consumption data (n = 166,911) were obtained from 24-h recalls in the 2005-2008 Nutrition and Health Surveys in Taiwan (NAHSIT). The average whole-group estimated daily intake (EDI_WG) was 0.018 (7.9% tolerable daily intake, TDI) for women of child-bearing age and 0.031 μg/day per kg body weight (13.6% TDI) for children. However, 95th percentile values (P95) of 90.4% TDI and 185% TDI were estimated for the two consumer-only populations, which have raised public health concerns. The ratio of % TDI to % daily reference intake (% DRI) was used as a risk-benefit (R/B) indicator. The top 4 R/B foods were: tuna sashimi (0.089 and 0.14), non-cooked shredded swordfish (0.033 and 0.052), fried-Spanish mackerel (0.027 and 0.043) and deep-fried fish balls (0.022 and 0.035) in the two perspective populations.

Environmental monitoring and benchmarking of VCM airborne emissions for a major PVC plant in Taiwan with 15 PVC plants in the USA

Vinyl chloride monomer (VCM) is classified as group 1 carcinogenic to humans by the International Agency for Research for Cancer (IARC). In 2012, USEPA promulgated a new VCM emission standard as part of National Emission Standards for Hazardous Air Pollutants (NESHAP) for polyvinyl chloride (PVC) and copolymer plants. The standard was set by benchmarking of peer plants with maximum achievable control technology (MACT). This study performs an emission assessment of a world-class PVC plant in Taiwan according to the MACT analysis. The emission data obtained were then benchmarked with baseline emission estimates of 15 PVC plants in the USA. Results of this study show seven types of VCM emissions: stripped resin of suspension/dispersion, wastewater, process vent, heat-exchange system, storage tank, equipment leaks, and other sources (gasholder). All the emission factors are complied with their MACT emission limitations (MEL) and ranked either #1 or #2 among the 15 plants. They are also summed and benchmarked against the production capacity of each plant, showing a negative power function with a fair correlation (R² = 0.73). Among seven types of emissions, stripped resin contributes the highest (51.7%) by average emission factor of the 15 plants plus this study plant.

Analyzing transient respirometric data by analytical algorithm for Monod kinetic parameters

This study aims to develop an analytical algorithm with oxygen update (O_u) data obtained from transient respirometric measurement. Based on Monod kinetics, this study formulates a novel two-phase analytical model for an oxygen uptake rate plot (OUR vs. O_u) obtained by respirometric techniques. The first phase is a hyperbolic equation relating to exogenous and endogenous respiration, while the second phase is a linear equation for endogenous respiration only. An algorithm was therefore developed to analyze four Monod parameters by locating the best phase-separating point at which the absolute average relative error (ARE) of OUR is minimized. An analysis using test data on acetate verified that the algorithm is capable of transient kinetic parameter estimation with an ARE below 5-10%. A sensitivity analysis on domestic wastewater coupled with a Monte Carlo simulation concluded that the kinetic test must be conducted at a relatively high initial substrate level (S_o/X_o ≧ 1 and S_o/K_s ≧ 10) for reliable parameter estimation. Moreover, it is crucial to conduct the kinetic test with sufficient and acclimated seed culture for the degradation of substrate. The results of this study can be used to develop an automatic transient kinetic analyzer with modern programmable respirometers.

Environmental health risks perception, attitude, and avoidance behaviour toward municipal solid waste incinerator

This study aims to assess the relationship between risk perception, attitude, and avoidance among residents toward an urban incinerator in Taichung, Taiwan. A cross-sectional study was conducted and three schools were enrolled. The case group was composed of 514 residents who live near an incinerator. The control group was composed of 264 people nearly the same age and who have lived in that area basically the same period of time. All participants were interviewed using a structured questionnaire. Results of this study showed that there was no significant difference between the exposure group and the control group in risk perception and attitude regarding the incinerator. However, the exposure group showed a significantly higher desire to move within one year or move sometime in the future than the control group. Therefore, these people should encourage the Environmental Protection Administration (EPA) to do everything it can to make sure that the incinerator operates safely.

Electricity production from municipal solid waste using microbial fuel cells

The organic content of municipal solid waste has long been an attractive source of renewable energy, mainly as a solid fuel in waste-to-energy plants. This study focuses on the potential to use microbial fuel cells to convert municipal solid waste organics into energy using various operational conditions. The results showed that two-chamber microbial fuel cells with carbon felt and carbon felt allocation had a higher maximal power density (20.12 and 30.47 mW m(-2) for 1.5 and 4 L, respectively) than those of other electrode plate allocations. Most two-chamber microbial fuel cells (1.5 and 4 L) had a higher maximal power density than single-chamber ones with corresponding electrode plate allocations. Municipal solid waste with alkali hydrolysis pre-treatment and K3Fe(CN)6 as an electron acceptor improved the maximal power density to 1817.88 mW m(-2) (~0.49% coulomb efficiency, from 0.05-0.49%). The maximal power density from experiments using individual 1.5 and 4 L two-chamber microbial fuel cells, and serial and parallel connections of 1.5 and 4 L two-chamber microbial fuel cells, was found to be in the order of individual 4 L (30.47 mW m(-2)) > serial connection of 1.5 and 4 L (27.75) > individual 1.5 L (20.12) > parallel connection of 1.5 and 4 L (17.04) two-chamber microbial fuel cells . The power density using municipal solid waste microbial fuel cells was compared with information in the literature and discussed.

Screening procedure for airborne pollutants emitted from a high-tech industrial complex in Taiwan

Despite the modernization of computational techniques, atmospheric dispersion modeling remains a complicated task as it involves the use of large amounts of interrelated data with wide variability. The continuously growing list of regulated air pollutants also increases the difficulty of this task. To address these challenges, this study aimed to develop a screening procedure for a long-term exposure scenario by generating a site-specific lookup table of hourly averaged dispersion factors (χ/Q), which could be evaluated by downwind distance, direction, and effective plume height only. To allow for such simplification, the average plume rise was weighted with the frequency distribution of meteorological data so that the prediction of χ/Q could be decoupled from the meteorological data. To illustrate this procedure, 20 receptors around a high-tech complex in Taiwan were selected. Five consecutive years of hourly meteorological data were acquired to generate a lookup table of χ/Q, as well as two regression formulas of plume rise as functions of downwind distance, buoyancy flux, and stack height. To calculate the concentrations for the selected receptors, a six-step Excel algorithm was programmed with four years of emission records and 10 most critical toxics were screened out. A validation check using Industrial Source Complex (ISC3) model with the same meteorological and emission data showed an acceptable overestimate of 6.7% in the average concentration of 10 nearby receptors. The procedure proposed in this study allows practical and focused emission management for a large industrial complex and can therefore be integrated into an air quality decision-making system.

Background levels of persistent organic pollutants in humans from Taiwan: perfluorooctane sulfonate and perfluorooctanoic acid

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have recently received attention due to their widespread contamination of the environment. PFOS and PFOA are stable in the environment and resistant to metabolism, hydrolysis, photolysis and biodegradation. PFOS and PFOA have been found in human blood and tissue samples from both occupationally exposed workers and the general worldwide population. This study aimed to determine the background levels of PFOS and PFOA in the Taiwanese population, investigate related factors, and compare exposure in Taiwan to that in other countries. The concentration of PFOS in the 59 serum samples collected from the general population in Taiwan ranged from 3.45 to 25.65ngmL(-1) (median: 8.52), and the concentration of PFOA ranged from 1.55 to 7.69ngmL(-1) (median: 3.22). There was a significant positive correlation (r=0.51; p<0.0001) between PFOS and PFOA concentrations. Males had higher concentrations of PFOA and PFOS than females. PFOS levels in serum increased with age. This study is the first investigation to reveal the PFOS and PFOA levels of serum samples in the general population of Taiwan. The levels of PFOS and PFOA in Taiwanese serum samples were comparable with those from other countries (PFOS: 5.0-35ngmL(-1), PFOA: 1.5-10ngmL(-1)).

Effects of spiked metals on the MSW anaerobic digestion

This study aimed to investigate the effects of eight metals on the anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) in bioreactors. Anaerobic bioreactors containing 200 mL MSW mixed completely with 200 m L sludge seeding. Ca and K (0, 1000, 2000 and 6,000 mg L(-1)) and Cr, Ni, Zn, Co, Mo and W (0, 5, 50 and 100 mg  L(-1)) of various dose were added to anaerobic bioreactors to examine their anaerobic digestion performance. Results showed that except K and Zn, Ca (~728 to ~1,461 mg  L(-1)), Cr (~0.0022 to ~0.0212 mg  L(-1)), Ni (~0.801 to ~5.362 mg  L(-1)), Co (~0.148 to ~0.580 mg  L(-1)), Mo (~0.044 to ~52.94 mg  L(-1)) and W (~0.658 to ~40.39 mg  L(-1)) had the potential to enhance the biogas production. On the other hand, except Mo and W, inhibitory concentrations IC(50) of Ca, K, Cr, Ni, Zn and Co were found to be ~3252, ~2097, ~0.124, ~7.239, ~0.482, ~8.625 mg  L(-1), respectively. Eight spiked metals showed that they were adsorbed by MSW to a different extent resulting in different liquid metals levels and potential stimulation and inhibition on MSW anaerobic digestion. These results were discussed and compared to results from literature.

The effect of prenatal perfluorinated chemicals exposures on pediatric atopy

BACKGROUND

The role of perfluorinated compounds (PFCs) in the immune system and allergic diseases is not well-known. This study examined the effects of pre-natal exposure to PFCs on immunoglobulin E (IgE) levels and atopic dermatitis (AD).

METHODS

In Taiwan Birth Panel cohort study, newborns with cord blood and peri-natal factors (i.e. birth body weight, weeks of gestation, and type of delivery) gathered at birth were evaluated. At the age of 2 years, information on the development of AD, environmental exposures, and serum total IgE were collected. The AD and non-AD children were compared for the concentration of cord blood serum PFCs measured by Ultra-performance liquid chromatography/triple-quadrupole mass (UPLC-MS/MS). Correlations among cord blood IgE, serum total IgE at 2 years of age, and cord blood PFC levels were made.

RESULTS

Of 244 children who completed the follow-up and specimen collections, 43 (17.6%) developed AD. Concentrations of cord blood serum perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS) were median (range) 1.71 (0.75-17.40), 5.50 (0.11-48.36), 2.30 (0.38-63.87), and 0.035 (0.035-0.420)ng/mL, respectively. PFOA and PFOS levels positively correlated with cord blood IgE levels (per ln-unit: β=0.134 KU/l, p=0.047 for PFOA; β=0.161 KU/l, p=0.017 for PFOS). Analyses stratified by gender revealed that PFOA and PFOS levels positively correlated with cord blood IgE levels only in boys (per ln-unit: β=0.206 KU/l, p=0.025 for PFOA; β=0.175 KU/l, p=0.053 for PFOS). When dividing cord blood serum PFCs into quartiles in the fully adjusted models, AD had no significant association with PFOS.

CONCLUSIONS

Pre-natal PFOA and PFOS exposures positively correlated with cord blood IgE levels.

Exploring the background features of acidic and basic air pollutants around an industrial complex using data mining approach

Air pollution data around a monitored site are normally difficult to analyze due to highly inter-related meteorological and topographical factors on top of many complicated atmospheric chemical interactions occurred in local and regional wind fields. The challenge prompts this study to develop a comprehensive data-mining algorithm of cluster analysis followed by meteorological and interspecies correlations to mitigate the inherent data complexity and dissimilarity. This study investigated the background features of acidic and basic air pollutants around a high-tech industrial park in Taiwan. Monthly samplings were taken at 10 sites around the park in a year. The temporal distribution plots show a baseline with two characteristic groups of high and low peaks. Hierarchical cluster analysis confirms that high peaks were primarily associated with low speed south wind in summer for all the chemical species, except for F(-), Cl(-), NH(3) and HF. Crosschecking with the topographical map identifies several major external sources in south and southwest. Further meteorological correlation suggests that HCl is highly positively associated with humidity, while Cl(-) is highly negatively associated with temperature, both for most stations. Interestingly, HNO(3) is highly negatively associated with wind speed for most stations and the hotspot was found in summer and around the foothill of Da-Tu Mountain in the northwest, a stagnant pocket on the study site. However, F(-) is highly positively associated with wind speed at downwind stations to the prevailing north wind in winter, indicating an internal source from the north. The presence of NH(4)(+) stimulates the formation of NO(3)(-), SO(4)(-2) (R=0.7), and HNO(3), H(2)SO(4), NH(3) (R=0.3-0.4). As H(2)SO(4) could be elevated to a level as high as 40% of the regulated standard, species interactions may be a dominate mechanism responsible for the substantial increase in summer from external sources.

Modeling biogas production from organic fraction of MSW co-digested with MSWI ashes in anaerobic bioreactors

This study aims at investigating the effects of MSW incinerator fly ash (FA) and bottom ash (BA) on the anaerobic co-digestion of OFMSW with FA or BA. It also simulates the biogas production from various dosed and control bioreactors. Results showed that suitable ashes addition (FA/MSW 10 and 20 g L(-1) and BA/MSW 100 g L(-1)) could improve the MSW anaerobic digestion and enhance the biogas production rates. FA/MSW 20 g L(-1) bioreactor had the higher biogas production and rate implying the potential option for MSW anaerobic co-digestion. Modeling studies showed that exponential plot simulated better for FA/MSW 10 g L(-1) and control bioreactors while Gaussian plot was applicable for FA/MSW 20 g L(-1) one. Linear and exponential plot of descending limb both simulated better for BA/MSW 100 g L(-1) bioreactor. Modified Gompertz plot showed higher correlation of biogas accumulation than exponential rise to maximum plot for all bioreactors.

Characterization of volatile organic compounds in the vicinity of an optoelectronics industrial park in Taiwan

This study aimed to determine the concentration of volatile organic compounds (VOCs) and investigate the impacts of traffic and industrial activities on the concentration of VOCs near the Central Taiwan Science Park (CTSP) in Taiwan during 2005. Twelve-hour canister sampling was performed at 10 sites near CTSP every season. Samples were analyzed by gas chromatography with a mass-selective detector. The traffic flow rate, industrial production rates, and meteorological information were also collected to assess their impacts on VOC concentrations using multiple linear regression models. The major components determined in the atmosphere were toluene (29.4-218.8 microg m(-3)), acetone (30-71.3 microg m(-3)), m/p-xylene (7.8-51.7 microg m(-3)), and ethanol (16.4-47.8 microg m(-3)); only ethanol revealed a pattern of increasing concentration from spring to winter. The log-transformed mean concentrations of toluene, acetone, and ethanol were significantly associated with the production rates of the optoelectronic companies after adjustment for traffic flow and meteorological factors (P < 0.05). There was no significant association between the total traffic flow rate and any log-transformed mean concentrations of VOCs. Each $1 million (U.S.) increase in optoelectronic sales was significantly associated with increasing mean concentrations of 1.29 +/- 1.08 microg m(-3) for toluene, 1.13 +/- 1.05 microg m(-3) for acetone, and 1.25 +/- 1.09 microg m(-3) for ethanol. The authors' findings suggest that optoelectronic industrial activities are still the predominant source for VOC emissions surrounding this industrial park.

Prediction of Cadmium uptake by brown rice and derivation of soil-plant transfer models to improve soil protection guidelines

Cadmium (Cd) levels in paddy fields across Taiwan have increased due to emission from industry. To ensure the production of rice that meets food quality standards, predictive models or suitable soil tests are needed to evaluate the quality of soils to be used for rice cropping. Levels of Cd in soil and rice grains were measured in 19 paddy fields across the western plains in Taiwan. Cadmium levels in soil range from less than 0.1 mg kg(-1) to 30 mg kg(-1). Measured Cd levels in brown rice were predicted very well (R(2) > 0.8) based on Cd and Zinc in a 0.01 M CaCl(2) extract or a soil-plant transfer model using the reactive soil Cd content, pH, and cation exchange capacity. In contrast to current soil quality standards used in Taiwan, such models are effective in identifying soils where Cd in rice will exceed food quality standards.

Novel modeling concept for evaluating the effects of cadmium and copper on heterotrophic growth and lysis rates in activated sludge process

A new modeling concept to evaluate the effects of cadmium and copper on heterotrophic growth rate constant (mu(H)) and lysis rate constant (b(H)) in activated sludge was introduced. The oxygen uptake rate (OUR) was employed to measure the constants. The results indicated that the mu(H) value decreased from 4.52 to 3.26 d(-1) or by 28% when 0.7 mg L(-1) of cadmium was added. Contrarily the b(H) value increased from 0.31 to 0.35 d(-1) or by 11%. When adding 0.7 mg L(-1) of copper, the mu(H) value decreased to 2.80 d(-1) or by 38%. The b(H) value increased to 0.42 d(-1) or by 35%. After regression, the inhibitory effect was in a good agreement with non-competitive inhibition kinetic. The inhibition coefficient values for cadmium and copper were 1.82 and 1.21 mg L(-1), respectively. The relation between the b(H) values and heavy metal concentrations agreed with exponential type well. The heavy metal would enhance b(H) value. Using these data, a new kinetic model was established and used to simulate the degree of inhibition. It was evident that not only the inhibitory effect on mu(H) but also that the enhancement effect on b(H) should be considered when heavy metal presented.

Biostabilization assessment of MSW co-disposed with MSWI fly ash in anaerobic bioreactors

Municipal solid waste incinerator (MSWI) fly ash has been examined for possible use as landfill interim cover. For this aim, three anaerobic bioreactors, 1.2m high and 0.2m in diameter, were used to assess the co-digestion or co-disposal performance of MSW and MSWI fly ash. Two bioreactors contained ratios of 10 and 20 g fly ash per liter of MSW (or 0.2 and 0.4 g g(-1) VS, that is, 0.2 and 0.4 g fly ash per gram volatile solids (VS) of MSW). The remaining bioreactor was used as control, without fly ash addition. The results showed that gas production rate was enhanced by the appropriate addition of MSWI fly ash, with a rate of approximately 6.5l day(-1)kg(-1)VS at peak production in the ash-added bioreactors, compared to approximately 4l day(-1)kg(-1)VS in control. Conductivity, alkali metals and VS in leachate were higher in the fly ash-added bioreactors compared to control. The results show that MSW decomposition was maintained throughout at near-neutral pH and might be improved by release of alkali and trace metals from fly ash. Heavy metals exerted no inhibitory effect on MSW digestion in all three bioreactors. These phenomena indicate that proper amounts of MSWI fly ash, co-disposed or co-digested with MSW, could facilitate bacterial activity, digestion efficiency and gas production rates.

Solubility of heavy metals added to MSW

This paper aims to investigate the six heavy metal levels (Cd, Cr, Cu, Pb, Ni and Zn) in municipal solid waste (MSW) at different pHs. It intends to provide the baseline information of metals solubility in MSW co-disposed or co-digested with MSW incinerator ashes in landfill or anaerobic bioreactors or heavy metals contaminated in anaerobic digesters. One milliliter (equal to 1mg) of each metal was added to the 100ml MSW and the batch reactor test was carried out. The results showed that higher HNO3 and NaOH were consumed at extreme pH of 1 and 13 compared to those from pH 2 to 11 due to the comparably higher buffer capacity. Pb was found to have the least soluble level, highest metal adsorption (%) and highest partitioning Kd (lg(-1)) between pH 3 and 12. In contrast, Ni showed the highest soluble level, lowest metal adsorption (%) and lowest Kd (lg(-1)) between pH 4 and 12. Except Ni and Cr, other four metals seemed to show the amphibious properties as comparative higher solubility was found in the acidic and basic conditions.

Respirometric evaluation by graphical analysis for microbial systems

Analysis of respirometric graphs for system diagnosis has recently drawn much attention due to the nature of the test being a fast method with reliable oxygen uptake (Ou) data. In this study, a new graphical analysis procedure is proposed, using the oxygen uptake rate (OUR) vs. Ou respirogram because of its distinct characteristics that provides easy visual inspection. The OUR plot is typically divided into two respiration phases, and each one of these phases can be simulated by a previously derived analytical equation. Based on the 2-phase model, five characteristic parameters (CPs) were derived for the OUR respirogram. Mathematically the 5 CPs can be related to the system parameters (SPs), including the four Monod kinetic parameters and two operating conditions (initial substrate and biomass concentration). Sensitivity analyses were then conducted to assess the 5 CPs for the level of effect caused by system parameters (SPs). This study also conducted respirometric tests under batch operation to evaluate the applicability of the graphical analysis method. Based on the 5 CPs estimated from the OUR respirogram of the tests, it can be concluded that respirometric tests normally experience the problems associated with initial lag, non-uniform seeding, and inadequate mixing.

Disinfection of hospital wastewater by continuous ozonization

The disinfection of hospital wastewaters using the ozonization process was studied. The concentrations of ozone required to reach a sudden drop of coliform and Pseudomonas aeruginosa in the wastewater are 4.0-7.0 and 3.0-5.0 mg L(-1), respectively. For the hospital wastewater, the disinfection efficiencies were 0.518S(-1.1) for coliforms, 0.509S(-1.06) for Pseudomonas aeruginosa and 0.254S-(1.54) for total count, respectively. As to the effects of ozone input methods on the disinfection efficiency, the continuous ozonization process was ten times higher than the batch input process. The low COD removal rate was obtained at 25.0 mgL(-1) of ozone concentration for hospital wastewater. However, more biodegradable compounds resulted in the treated mixture.

Dimensional analysis for establishing the testing criteria of kinetic study with respirometry

The kinetic study of a microbial system requires the determination of kinetic parameters under a set of operating variables. Previous researchers indicated that initial conditions, such as S0/X0 and S0/KS may influence the reliability of the parameter estimation. However, little study has been done to identify the sensitivity of system variables to the parameter estimation. This study proposes a novel dimensional analysis and identifies six dimensionless groups: mu(m)/fw, kd/fw, Yg, S0/KS, KS/S0, and 1/(fw theta(c) - 1). By incorporating the SP-moving algorithm proposed by Wu and coworkers in 2001, an algorithm was proposed in this study to perform a sensitivity analysis on the six dimensionless groups. Results of this analysis reveal that S0/X0 is more sensitive than S0/KS, as also evidenced by the fact that gross growth yield (Yg) is sensitive and affecting S0/X0. The analysis also suggests that the theta(c)-based wasting frequency (fw theta(c)) is more sensitive than the daily wasting frequency (fw). A critical minimum value of 1.3 for S0/X0 and a maximum value of 0.1 for S0/KS were suggested to establish the testing criteria for the kinetic study under the respirometric conditions.

Effect of dietary cholesterol and fat levels on lipid peroxidation and the activities of antioxidant enzymes in rats

The aim of this study was to investigate the effect of dietary fat levels, with or without cholesterol, on lipid peroxidation and the activities of antioxidant enzymes in rats. Thirty-two Wistar rats aged 4 weeks were divided into 4 groups and fed high (20%; HF) or low (5%; LF) fat, with or without 1% cholesterol, for 6 weeks. Cholesterol feeding resulted in significantly higher concentrations of serum cholesterol, but lowered serum triacylglycerol levels. Cholesterol feeding also led to markedly decreased levels of hepatic thiobarbituric acid reactive substances (TBARS) and lower activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase, and glucose-6-phosphate dehydrogenase (G6PDH) when compared with cholesterol-free counterparts in both HF and LF diets. On the other hand, rats fed high-fat diets showed increased serum and liver TBARS, but decreased hepatic GSH-Px, SOD, and G6PDH activities. Hepatic catalase activity was lower in rats fed cholesterol-containing diets, but higher in rats fed high-fat diets, and interaction existed between cholesterol and fat feeding. These results suggested that dietary cholesterol might delay lipid peroxidation and decrease the activities of the hepatic antioxidant enzymes. The degree of lipid peroxidation was also influenced by dietary fat levels.

Green fluorescent protein rendered susceptible to proteolysis: positions for protease-sensitive insertions

The green fluorescent protein (GFP) is highly resistant to proteolysis and remains uncleaved after prolonged incubation with trypsin or pronase despite several putative tryptic and chymotryptic sites in exposed loops. We have rendered GFP sensitive to proteolysis by inserting five amino acids, IEGRS, in loops at position 157, 172, or 189. Excitation and emission maxima of the three insertion mutants were similar to those of wild type, but quantum yields of mutants Omega172 and Omega189 were lower, indicating increased freedom of the fluorophore. Trypsin cleaved the native (folded) form of each mutant at a unique site defined by the insert. Pronase also yields similar digestion patterns in these variants, but further proteolysis was also observed, suggesting that the primary cleavage relaxes GFP structure and reveals previously inaccessible sites. Fluorescence of Omega189 changed little upon digestion with trypsin but decreased progressively by as much as 40% upon digestion with increasing amounts of pronase. Fluorescence of other variants was not affected significantly by the proteases, further confirming the remarkable stabilities of GFP variants. These constructs define a new conformation-sensitive site around residue 189 of GFP and show that GFP may be useful for design of protease-susceptible molecules for monitoring of specific proteolytic activities in vivo.

Full-scale evaluation of heat balance for autothermal thermophilic aerobic treatment of food processing wastewater

A full-scale autothermal thermophilic aerobic treatment (ATAT) of food-processing wastewater was evaluated in this study. The wastewater was rich in oil and grease at concentrations of 1,500-2,000 mg/L. The system has been operated for more than one and a half years since the startup. Under steady state conditions, the ATAT process was capable of spontaneous reaction at temperatures of 45-55 degrees C without the addition of external heat. Treatment efficiency was as high as 95% in COD reduction at a volumetric COD loading of 4.1 kg/m3-d. A mathematical heat balance model was developed based on the theoretical considerations of heat sources and losses for the ATAT process. A computer algorithm was established to evaluate specific heat potential (Hs) of the wastewater under steady state conditions. Six months of steady-state data were used for the evaluation. The result shows that on average the wastewater had a specific heat potential (Hs) of 4,720 kcal/kg-COD removed and the biological heat contributed 41.4% of the total heat input. A net heat flux of 4,270 kcal/min and volumetric heat intensity (Hv) of 38.0 kcal/L was necessary to maintain reaction temperature at 48.2 degrees C for the ATAT process. The full-scale ATAT process showed the typical characteristics of high removal rate, low sludge yield, and poor solids settleability for thermophilic aerobic treatment reported in the literature.

The Swedish Two-County Trial twenty years later. Updated mortality results and new insights from long-term follow-up

The benefit of invitation to mammographic screening observed in this trial is maintained as a highly significant 32% reduction in breast cancer mortality. Mammographic screening for breast cancer continues to save lives after up to 20 years. Screening derives this benefit by improving the distribution of tumors diagnosed with respect to prognostic categories based on node status, size, and histology of tumors. There is potential for modern screening programs with shorter interscreening intervals to achieve even greater improvements in prognostic category and greater reductions in breast cancer mortality. Mammography can discriminate a subpopulation of high-risk cases, those displaying casting-type calcifications on the mammogram, among very small tumors, with fundamental implications for diagnosis and treatment.

A novel method for prediction of long-term outcome of women with T1a, T1b, and 10-14 mm invasive breast cancers: a prospective study

BACKGROUND

Women with small mammographically detected breast cancers generally have good long-term outcomes, but a few with T1a (1-5 mm) and T1b (6-10 mm) tumours will eventually die from breast cancer. We investigated whether women at high risk of breast-cancer death could be identified with mammographic criteria and differentiated from women with small cancers of the breast and good outcomes.

METHODS

We prospectively applied mammographic classifications of tumour type to a consecutive series of 343 mammograms of invasive breast cancers of size 1-14 mm. Classifications were: stellate (spiculated) mass with no calcifications; circular or oval lesions with no calcifications; spiculated or circular lesions with non-casting-type calcifications; and casting-type calcifications.

FINDINGS

20-year survival for women with 1-14 mm invasive tumours with casting-type calcifications was 55%. 14% of 138 women with 1-9 mm tumours had casting-type calcifications on mammography, which accounted for 73% of all breast-cancer deaths (p<0.001). T1a, T1b, and 10-14 mm tumours with casting-type calcifications behaved as if they were larger lesions, since the rate of death was similar to that for women with advanced high-grade tumours. Most women who died were node-negative. The long-term survival of women who had tumours of 1-9 mm with no casting-type calcifications was about 95%.

INTERPRETATION

Mammographic classification seemed to reliably predict good and bad long-term outcomes for survival in tumours of 14 mm or smaller, and especially for those smaller than 10 mm. The implications for therapy are substantial.

Activity of granzyme A, a serine protease in the killing granules of cytotoxic T lymphocytes, is reduced in cells from HIV-infected hemophiliacs

Cytotoxic CD8+ lymphocytes (CTLs) kill virally infected target cells by releasing cytotoxic granules. The primary objective of this study was to determine whether the activity of granzyme A, a serine protease in the killing granules of CTLs is altered in HIV-infected hemophiliacs. A sensitive colorimetric assay that measures cleavage of a synthetic substrate, N alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester (BLT), was used to quantitate granzyme A activity. Granzyme A activities from hemophiliacs were normalized to to granzyme A activities of healthy donors run concurrently. Granzyme A activity in CD8+ T cells from HIV-seropositive hemophiliacs was significantly lower than granzyme A activity in cells from HIV-seronegative hemophiliacs (0.48 units +/- 0.086/CD8+ T cell and 1.573 +/- 0.434 units/CD8+ T cell, respectively; p < 0.005). These results indicate that cytotoxic cells in HIV-infected hemophiliacs have reduced granzyme A activity, which may result in a defect in CTL-mediated cell killing in these patients.

Purification of chlorpromazine-sensitive GTPase from rat cerebral cortex

The chlorpromazine-sensitive GTPase from the cell membrane of rat cerebral cortex was purified to homogenity by using DEAE Bio-Gel A agarose, hydroxyapatite and heparin agarose chromatography. The purified chlorpromazine-sensitive GTPase was purified 370-fold to obtain a final specific activity of 40 mumol GTP hydrolyzed2min/mg protein. The purified enzyme was inhibited by chlorpromazine but not by compound 48/80. Magnesium was required for its activity instead of calcium. The purified enzyme had an apparent pH optimum of 8.0, and molecular weight was estimated to be 58,000.

Purification of phospholipase C from rat cerebral cortex

Phospholipase C from rat cerebral cortex was purified to homogeneity by use of DEAE Bio-Gel A agarose, hydroxyapatite, and heparin agarose chromatography. The purified phospholipase C (PLC) was purified 622.4-fold and its molecular weight is estimated to be 97,500. We obtained a final specific activity of 3.112 mumol of phosphatidylinositol hydrolyzed/min/mg of protein. It is specific for inositol phospholipids. The purified enzyme has an apparent optimum pH 7.0. Calcium is required for its activity. Western blotting analysis showed that two proteins were recognized by anti-PLC antiserum.

Stimulation of inositol phosphate production and GTPase activity by compound 48/80 in rat peritoneal mast cells

Phospholipase C activity, GTPase activity and cytosolic-free calcium concentration in mast cells were stimulated by compound 48/80. Accumulation of inositol phosphates in rat mast cells was stimulated by guanosine 5'-[gamma-thio]-triphosphate. Guanosine 5'-[gamma-thio]triphosphate, however, exhibited no effect upon the purified phospholipase C activity and upon phospholipase C in the mast cell homogenate. The stimulatory effect of compound 48/80 upon phospholipase C activity of intact mast cells was observed to have been well correlated with that on GTPase activity of mast cell homogenate. Compound 48/80 exhibited no effect upon the binding of radioactive guanosine 5'-[gamma-thio]triphosphate to mast cell homogenate. Phospholipase C activity was verified by the above results to become affected by compound 48/80 through guanine nucleotide-binding regulatory protein.

Effects of bradykinin, GTP gamma S, R59022 and N-ethylmaleimide on inositol phosphate production in NG108-15 cells

Accumulation of inositol phosphates in NG108-15 neuroblastoma x glioma hybrid cells, pre-labeled for 24h to equilibrium, was stimulated by bradykinin, guanosine 5'-O-(3-thiotriphosphate) and the diacylglycerol kinase inhibitor R59022. Only the stimulation by bradykinin was inhibited by the bradykinin receptor antagonist [D-Arg0, Hyp3, Phe7, Thi5,8] bradykinin. Neither bradykinin nor R059022 increased the labeling of the inositol phospholipids. The sulfhydryl-alkylating reagent N-ethylmaleimide at 100 microM essentially abolished the stimulation caused by all three agents, possibly by preventing the binding of GTP to a guanine nucleotide-binding regulatory protein of as yet unknown size.

Purification of phosphatidylinositol-specific phospholipase C from NG108-15 cells

The phosphatidylinositol-specific phospholipase C from the membrane of NG108-15 cells has been purified to homogeneity by using DEAE Bio-Gel A agarose, hydroxyapatite, and heparin agarose chromatography. The purified phosphatidylinositol-specific phospholipase C has been purified 422-fold and its molecular weight has been estimated to be 28,000. We have obtained a final specific activity of 3.8 mumols of phosphatidylinositol hydrolyzed/min/mg of protein. The purified enzyme is specific to phosphatidylinositol. The purified enzyme has an apparent pH optimum of 7.0. Calcium ions are required for its activity.

Immunological changes after hyposensitization in house-dust-sensitive asthmatic children: a review

Patients with allergic diseases are characterized by the presence of elevated total serum IgE and specific IgE antibodies against a variety of environmental allergens. To explore the causes for augmented IgE antibody production and the working mechanisms of hyposensitization (HS), a series of studies has been conducted on house-dust-sensitive, newly diagnosed, and hyposensitized asthmatic children and normals. The specific IgE and IgG antibodies were measured by radioallergosorbent test; the lymphoproliferative capability was measured by 3H-thymidine incorporation; the allergen-specific suppressor activity was determined by the extent of house-dust-activated, interleukin-2 (IL-2)-expanded lymphocytes to suppress the allergen-induced proliferation of autologous mononuclear cells (MNC); and IL-2 was produced by stimulating MNC with allergen or phytohemagglutinin (PHA) and quantitated by its capability to support the proliferation of mouse IL-2-dependent cytotoxic T-cell line. The results showed: 1) HS was effective in 90% of patients in terms of decreased attacks and medication taken; 2) the patients were defective in suppressor T-cell function for IgE production; 3) HS was able to restore the regulatory T-cell function and increase the production of IgG-blocking antibody; and 4) IL-2 production may be used as an indicator for initiation and discontinuation of HS. Therefore, hyposensitization is an effective and specific treatment for allergic bronchial asthma and can partially correct an immunoregulatory aberration in atopic individuals.

Solubilization and purification of hepatic microsomal trans-2-enoyl-CoA reductase: evidence for the existence of a second long-chain enoyl-CoA reductase

The present study describes the solubilization and purification of a NADPH-specific trans-2-enoyl-CoA reductase from rat liver microsomes. The final preparation was purified to near homogeneity and had a minimal molecular weight of 51,000 +/- 2,000, as judged by sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis. This enzyme specifically used NADPH, as cofactor, and was chromatographically (2',5'-ADP-agarose) separated from another trans-2-enoyl-CoA reductase which utilized either NADH or NADPH as cofactor. The NADPH-specific trans-2-enoyl-CoA reductase catalyzed the reduction of trans-2-enoyl-CoAs from 4 to 16 carbon units. The Km values for crotonyl-CoA, trans-2-hexenoyl-CoA, and trans-2-hexadecenoyl-CoA were 20, 0.5, and 1.0 microM, while the Km value for NADPH was 10 microM. Although N-ethylmaleimide, heat treatment, and limited proteolysis with trypsin affected the reduction of short-chain (C4) and long-chain (C16) substrates equally, and in spite of the fact that a single protein band was observed on SDS-gels, at the present time one cannot state unequivocally that the purified preparation contained only one reductase. trans-2-Hexenoyl-CoA, for example, did not inhibit the reduction of trans-2-hexadecenoyl-CoA to palmitoyl-CoA and trans-2-decenoyl-CoA to decanoyl-CoA whereas it strongly inhibited the conversion of crotonyl-CoA to butyryl-CoA. The potential implications of this finding are discussed. Finally, the reductase preparation was shown not to contain either heme, nonheme iron, or a flavin prosthetic group.