Biochemical study of retired pentachlorophenol workers with and without following dietary exposure to PCDD/Fs.

PCDD/Fs are found as impurities in commercial pesticide sodium pentachlorophenol (Na-PCP) salt. We compared, using multivariate logistic regression analysis adjusted for confounding factors, serum PCDD/F levels and biochemical examinations of retired Na-PCP workers and other inhabitants living near a closed Na-PCP plant that discharged PCP-contaminated wastewater into a nearby pond in Tainan, Taiwan. In this cross-sectional study from October 2006 through May 2009, 1167 participants were divided into groups according to their occupational (retired Na-PCP plant workers versus other residents) and dietary exposure (eating polluted fish versus not eating polluted fish) to PCDD/Fs, and a general population from a large-scale survey. Serum PCDD/F levels were significantly different between these groups (range: from 22.9±10.0pg WHO(98)-TEQ(DF) g(-1) lipid in the general population to 109.6±94.5pg WHO(98)-TEQ(DF) g(-1) lipid in retired Na-PCP workers eating polluted seafood; P(trend)<0.001). Distinct patterns of PCDD/Fs congener profiles, showing a significantly higher proportion of 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxDD, and less 2,3,4,6,7,8-HpCDF, OCDF, were also found among workers and residents with different serum PCDD/F levels versus the general population. After adjusting for confounding factors, glucose (adjusted odds ratio [AOR] 7.22 [95% CI: 4.04-12.90]), triglycerides (AOR 4.31 [95% CI: 2.57-7.22]), blood urea nitrogen (AOR 2.90 [95% CI: 1.58-5.33]), creatine (AOR 5.83 [95% CI: 1.12-30.30]) and total protein (AOR 3.74 [95% CI: 1.91-7.31]) levels in retired workers were significantly higher than in the reference group. Occupational exposure to PCDD/Fs is associated with biochemical abnormalities that may persist for years after serum PCDD/F levels have declined.

Predicted risk of childhood allergy, asthma, and reported symptoms using measured phthalate exposure in dust and urine.

UNLABELLED: The associated risk of phthalate exposure, both parent compounds in the home and their metabolites in urine, to childhood allergic and respiratory morbidity, after adjusting for exposures of indoor pollutants, especially bioaerosols, was comprehensively assessed. Levels of five phthalates in settled dust from the homes of 101 children (3-9 years old) were measured, along with their corresponding urinary metabolites. Other environmental risk factors, including indoor CO2, PM2.5, formaldehyde, 1,3-ß-D-glucan, endotoxin, allergen and fungal levels, were concomitantly examined. Subject's health status was verified by pediatricians, and parents recorded observed daily symptoms of their children for the week that the home investigation visit took place. Significantly increased level of benzylbutyl phthalate, in settled dust, was associated with test case subjects (allergic or asthmatic children). Higher levels of dibutyl phthalate and its metabolites, mono-n-butyl phthalate, and mono-2-ethylhexyl phthalate were found to be the potential risk factors for the health outcomes of interest. Similarly, indoor fungal exposure remained a significant risk factor, especially for reported respiratory symptoms. The relative contribution from exposure to phthalates and indoor biocontaminants in childhood allergic and respiratory morbidity is, for the first time, quantitatively assessed and characterized. PRACTICAL IMPLICATIONS: For asthmatic and allergic children living in subtropical and highly developed environments like homes in Taiwan, controlling environmental exposure of phthalates may be viewed as equally important as avoiding indoor microbial burdens, for the management of allergy-related diseases. It is also recognized that multidisciplinary efforts will be critical in realizing the true underlying mechanisms associated with these observations.

Inhibitory Effects of Chinese Medicinal Herbs on Plant-Pathogenic Bacteria and Identification of the Active Components from Gallnuts of Chinese Sumac.

The aqueous extracts of 30 out of 67 Chinese medicinal herbs were shown to have inhibitory effects on growth of Xanthomonas euvesicatoria by a paper disc diffusion assay. The inhibitory substances with the strongest antibacterial activity were extracted from Chinese sumac gallnut and black myrobalan. The aqueous extract of gallnut inhibited the growth of eight of the tested plant-pathogenic bacteria, and that of black myrobalan inhibited five. The gallnut extract produced at least an 8-mm inhibition zone against Acidovorax citrulli, Ralstonia solanacearum, X. citri pv. citri, and X. euvesicatoria at a 10-fold dilution, and it was still active at 800- to 1,600-fold dilutions. The aqueous extract of gallnut was more inhibitory than the acetone-water extract. To identify the inhibitory compounds in the gallnut aqueous extract, the crude extract was chromatographed over a silica column, and the primary compounds in fractions 3 and 8 were identified by nuclear magnetic resonance as gallic acid and methyl gallate, respectively. The inhibitory effect of methyl gallate on the growth of four plant-pathogenic bacteria was 10 to 80 times that of gallic acid. The minimum inhibition and minimum bactericidal concentration tests showed that the inhibition effect of the original aqueous was higher than that of methyl gallate. These results indicate that methyl gallate in gallnut is an important compound that is inhibitory to plant-pathogenic bacterial growth, and there are other unidentified compounds that are also responsible for the antibacterial effects. This is the first report regarding the antibacterial effects of gallnut extract and its chemical components on plant-pathogenic bacteria.

A dose-dependent relationship between the severity of visible mold growth and IgE levels of pre-school-aged resident children in Taiwan.

UNLABELLED: To demonstrate a dose-dependent relationship between severity of indoor visible mold growth and serum total IgE levels of resident children. A total of 97 children (4-7 years old) identified from previously established birth-cohort, with information pertaining to indoor environmental conditions after child's birth, were successfully recruited while sera were concurrently collected for total IgE and specific IgE analysis during clinical visits. Severity of visible mold growth at homes was scaled into three levels accordingly. A statistically significant dose-dependent relationship was found between severity of indoor visible mold growth and total serum IgE levels. The trend sustains after the model was adjusted for resident child's age, gender, pet-keeping history, number of siblings, atopic history of parents, presence of incense burning, and environmental tobacco smoking (ETS) at home. Further analysis of specific IgE to commonly examined fungal allergens did not substantiate the correlation. Rather, resident child's specific IgE to mite allergens, although without statistical significance, seemed to better associate with the ranked severity of indoor mold growth in this study. An adjuvant role of fungal exposure to enhance sensitization in indoor environment is therefore suggested in Taiwanese population with high prevalence of building dampness. PRACTICAL IMPLICATIONS: The presence of indoor visible mold growth, potentially resulting in fungal exposure, was not associated directly with changing biomarker levels of allergic response in resident children, rather playing an adjuvant role to enhance sensitization. On the other hand, other allergens, such as mite allergen examined in this study, appeared to support a more plausible etiology for directly triggering the ultimate allergic symptoms and diseases of interest. Evidence as such may derive different priority-setting when designing preventive measures for managing indoor air quality.

High variation of PCDDs, PCDFs, and dioxin-like PCBs ratio in cooked food from the first total diet survey in Taiwan.

This study determined the levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in 240 individual food samples, belonging to 37 different foodstuffs in first total diet study (TDS) in Taiwan. The foods were collected from markets located in eight cities or counties around Taiwan. The food was cooked in a laboratory according to recipes typically used in Taiwan. In this study, PCDD/Fs were lower than the limits proposed by the European Union (EU) regulation for commercialized food, except for a notable PCDD/Fs level in ducks (3.660 pg WHO-TEQ/g, fat) obtained from central Taiwan. We hypothesize the duck meat might be probably polluted via emission of a fly ash recycling plant located near the duck farms. In addition to fish, most foods had high PCDD/Fs to dl-PCBs ratio. Needle fish and sea perch had relatively lower PCDD/Fs and dl-PCBs levels compared with those in other fish. Data from this study can be utilized for further consideration about dietary intake.

Role of ventilation in airborne transmission of infectious agents in the built environment - a multidisciplinary systematic review.

There have been few recent studies demonstrating a definitive association between the transmission of airborne infections and the ventilation of buildings. The severe acute respiratory syndrome (SARS) epidemic in 2003 and current concerns about the risk of an avian influenza (H5N1) pandemic, have made a review of this area timely. We searched the major literature databases between 1960 and 2005, and then screened titles and abstracts, and finally selected 40 original studies based on a set of criteria. We established a review panel comprising medical and engineering experts in the fields of microbiology, medicine, epidemiology, indoor air quality, building ventilation, etc. Most panel members had experience with research into the 2003 SARS epidemic. The panel systematically assessed 40 original studies through both individual assessment and a 2-day face-to-face consensus meeting. Ten of 40 studies reviewed were considered to be conclusive with regard to the association between building ventilation and the transmission of airborne infection. There is strong and sufficient evidence to demonstrate the association between ventilation, air movements in buildings and the transmission/spread of infectious diseases such as measles, tuberculosis, chickenpox, influenza, smallpox and SARS. There is insufficient data to specify and quantify the minimum ventilation requirements in hospitals, schools, offices, homes and isolation rooms in relation to spread of infectious diseases via the airborne route. PRACTICAL IMPLICATION: The strong and sufficient evidence of the association between ventilation, the control of airflow direction in buildings, and the transmission and spread of infectious diseases supports the use of negatively pressurized isolation rooms for patients with these diseases in hospitals, in addition to the use of other engineering control methods. However, the lack of sufficient data on the specification and quantification of the minimum ventilation requirements in hospitals, schools and offices in relation to the spread of airborne infectious diseases, suggest the existence of a knowledge gap. Our study reveals a strong need for a multidisciplinary study in investigating disease outbreaks, and the impact of indoor air environments on the spread of airborne infectious diseases.

High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: influence of contaminated fish consumption.

An abandoned pentachlorophenol plant and nearby area in southern Taiwan was heavily contaminated by dioxins, impurities formed in the PCP production process. The investigation showed that the average serum PCDD/Fs of residents living nearby area (62.5 pg WHO-TEQ/g lipid) was higher than those living in the non-polluted area (22.5 and 18.2 pg WHO-TEQ/g lipid) (P<0.05). In biota samples, average PCDD/F of milkfish in sea reservoir (28.3 pg WHO-TEQ/g) was higher than those in the nearby fish farm (0.15 pg WHO-TEQ/g), and Tilapia and shrimp showed the similar trend. The average daily PCDD/Fs intake of 38% participants was higher than 4 pg WHO-TEQ/kg/day suggested by the world health organization. Serum PCDD/F was positively associated with average daily intake (ADI) after adjustment for age, sex, BMI, and smoking status. In addition, a prospective cohort study is suggested to determine the long-term health effects on the people living near factory.

First Report of the Causal Agent of Huanglongbing ("Candidatus Liberibacter asiaticus") Infecting Kumquat in Taiwan.

Huanglongbing (greening) disease caused by a nonculturable, phloem-limited bacterium is a severe disease of citrus. On the basis of the influence of temperature on host symptoms and the causal agent, this disease can be categorized as Asian caused by "Candidatus Liberibacter asiaticus", African caused by "Ca. L. africanus", and American caused by "Ca. L. americanus". Kumquat (Fortunella margarita (Lour.) Swingle), a member of the Rutaceae is an economically important crop for export and local consumption in Taiwan. Recently, a Huanglongbing-like disease was found on kumquat in Yilan County, the largest kumquat-producing area in northeastern Taiwan. Even though the disease has been reported on Citrus spp. from Taiwan, it has never been reported on kumquat. Symptoms of infected kumquat were mottling, yellowing, hardening, and curling of leaves followed by premature defoliation, twig dieback, decay of feeder rootlets and lateral roots, and ultimately the death of the entire plant. Typical sieve-tube-restricted bacteria were observed in kumquat cells by electron microscopy (1). In addition, psyllid-transmission tests demonstrated that the Asian psyllid (Diaphorina citri) could transmit this bacterium to healthy kumquats. Positive bud graft transmissions were obtained to F. margarita, F. japonica (Thunb.) Swingle, F. obovata Hort. ex Tanaka, Luchen sweet orange (Citrus sinensis (L.) Osb.), and Wentan pummelo (C. maxima f. sp. butan Hay.). These inoculated plants showed symptoms in 3 to 8 months, and bacteria could be detected by polymerase chain reaction (PCR) using a common primer pair that amplified a 226-bp specific DNA fragment (2). For further molecular identification, the bacterial DNA was extracted from the inoculated plants and PCR was performed by using two sets of primers selected from the 16S rRNA region (GenBank Accession No. L22532) and 16S/23S intergenic spacer region (GenBank Accession No. AB019793). The expected DNA fragments of 1,389 bp and 862 bp were, respectively, amplified from symptomatic plants but not from healthy plants. The PCR products were cloned and sequenced (GenBank Accession Nos. DQ302750 and DQ207841). The 16S rRNA has 98 to 99% identity and 16S/23S intergenic spacer region has 99% identity to the corresponding region of "Ca. L. asiaticus" in GenBank. These molecular analyses confirm the presence of "Ca. L. asiaticus" in kumquat. Since Huanglongbing has been rarely reported naturally on kumquat, further analysis of this bacterium as a special strain of "Ca. L. asiaticus" is needed. References: (1) M. Garnier et al. Ann. Microbiol. 135A:169, 1984. (2) T. H. Hung et al. J. Phytopathol. 147:599, 1999.

Changing microbial concentrations are associated with ventilation performance in Taiwan's air-conditioned office buildings.

UNLABELLED: Our study conducted serial environmental measurements in 12 large office buildings with two different ventilation designs to obtain airborne microbial concentrations in typical office buildings, and to examine the effects of occupant density, ventilation type and air exchange efficiency on indoor microbial concentrations. Duplicate samples of airborne fungi and bacteria, a total of 2477 measurements, were collected based on a scheme of conducting sampling three times a day for at least seven consecutive days at every study building. Air change rates (ACHs) were also estimated by tracer gas concentration decay method, and measured by continuous Multi-Gas monitor for each building. Most sampling sites were with total fungal and bacteria concentrations higher than 1000 CFU/m(3), an often-quoted guideline in earlier research. Significantly higher concentrations of fungi and bacteria, as well as higher indoor/outdoor (I/O) ratios across most groups of airborne microbes, were identified in buildings with fan coil unit (FCU) system than those with air-handling unit (AHU) system (Student's t test, P < 0.0001). Older buildings and higher air exchange rates were statistically associated with greater indoor bacteria levels in FCU ventilated buildings (R(2) = 0.452); a pattern not found in AHU buildings. Increasing ACH seemed to be the determinant factor for rising indoor fungal and Cladosporium concentrations in those FCU buildings (R(2) = 0.346; 0.518). Our data indicated that FCU ventilated buildings might have provided more outdoor matters into indoor environments through direct penetration of outdoor air. Results also demonstrated a quantitative association between rising numbers of occupants and increasing indoor levels of yeast in both FCU and AHU ventilated buildings. The regression model identified in this study may be considered a reference value for proposing an optimal ACH, while with adequate filtration of fresh air, as an effective strategy in lowering indoor microbial concentrations in air-conditioned buildings. PRACTICAL IMPLICATIONS: As control of indoor microbial contamination has become an increasing concern around the world, feasibility and effectiveness of adopting ventilation approach has attracted a significant interest. This field investigation demonstrated, quantitatively, critical variables to be taken into consideration while applying such a measure, including the kinds of microbes to be removed and the types of ventilation system already in place.

First Report of Bougainvillea spectabilis chlorotic vein-banding virus Infecting Bougainvillea Plants in Taiwan.

Bougainvillea (Bougainvillea spectabilis), native to Amazonian rainforests in South America, is an important ornamental and landscaping plant that is widely distributed in tropical and subtropical areas. A new virus disease, Bougainvillea chlorotic vein-banding, caused by a Badnavirus, Bougainvillea spectabilis chlorotic vein-banding virus (BsCVBV), was first reported in Brazil in 2001 (1) and recently discovered in Taiwan. Infected bougainvillea developed symptoms such as mottling, chlorosis, vein-banding, and stunting. Severe leaf-distortion symptoms were observed in the susceptible hybrid Taipei Red, the most popular bougainvillea cultivar in Taiwan. In electron microscopic observations, typical bacilliform virions measuring 28 × 130 to 150 nm were observed in infected bougainvillea cells. In addition, our transmission tests demonstrated that the virus could be easily transmitted among different bougainvillea cultivars by bud grafting but not by mechanical inoculation. Bougainvillea plants showed apparent symptoms 1 month after grafting. For molecular identification, viral DNA was extracted from the test plants (2), and polymerase chain reaction (PCR) was performed using the primers selected from the DNA sequences of ORF III of Sugarcane bacilliform virus (GenBank Accession No. M89923). The sequence of the forward primer was 5'-TCA AAG TTT GAT TTG AAG AGC GGG-3' and the sequence of the reverse primer was 5'-CTT GCA TAC TGC TCC CCA TCC-3' The primers amplified a 676-bp PCR product (GenBank Accession No. DQ103759). Nucleotide and deduced amino acid sequences were 82 and 90% identical, respectively, to the corresponding region of the Brazilian strain of BsCVBV (GenBank Accession No. AY532653). These data indicate that the bougainvillea disease occurring in Taiwan is caused by a strain of BsCVBV. Reference: (1) C. M. Chagas et al. Virus Rev. Res. 6:153, 2001. (2) H.-J. Su et al. J. Phytopathol. 151:290, 2003.

The topical application of 2,3,7,8-tetrachlorodibenzo-p-dioxin lacks skin tumor-promoting potency but induces hepatic injury and tumor necrosis factor-alpha expression in ICR male mice.

One of the most toxic environmental pollutants known to man is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). There is growing evidence that indicates TCDD is a potent tumor promoter in rat and mouse liver, as well as in mouse skin. The mouse skin carcinogenesis model has been used extensively to assess whether a chemical or physical agent carries a carcinogenic hazard to humans and to define the mechanism involved with the carcinogenic effects. We applied the mouse skin model to ICR male mice and the results showed that following the application of DMBA, repeated dorsal application of all doses of TCDD produced no papillomas. These findings imply that the ICR male mouse is an extremely insensitive strain as a TCDD-induced two-stage mouse skin carcinogenesis model. However, severe hepatic injuries and wasting syndrome were seen in mice treated topically with TCDD. Meanwhile, serum TNF-alpha levels increased during the experimental periods. Inflammatory cell infiltration, fatty liver, and nodule formation could be observed in damaged livers. Elevated hepatic EROD activity and urinary 8-epi-PGF2alpha were also observed in mice with short-term exposure of TCDD.

Serum PCDD/F concentration distribution in residents living in the vicinity of an incinerator and its association with predicted ambient dioxin exposure.

The aim of this study was to evaluate the serum polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) concentration distribution in residents living in the vicinity of an incinerator and its association with annual ambient dioxin exposure predicted by an atmospheric dispersion model. A municipal waste incinerator in Northern Taiwan was chosen for this study. This incinerator had been in operation for 6 years at the time of this study. Using the incinerator site as the center, based on the simulated ambient annual average PCDD/F concentrations. Ninety-five volunteers, all live within a radius of 5 km from the incinerator for at least 5 years, who had no occupational exposure potential, were selected based on the population distribution in each district. The average serum PCDD/F concentration for these subjects living within four zones was about 14 pg I-TEQ/g lipid. The serum distribution levels of people of the four study zones, however, were not consistent with the predicted ambient levels. Results also suggest that ambient exposure might not be the most important contributor to serum concentrations when compared to other exposure sources, such as dietary intake.

Polymorphisms in GSTT1 and p53 and urinary transitional cell carcinoma in south-western Taiwan: a preliminary study.

Little is known about the relevance of genetic polymorphisms to arsenic-related bladder cancer. A preliminary case-control study was conducted to explore the association between genetic polymorphisms of GSTT1, p53 codon 72 and bladder cancer in southern Taiwan, a former high arsenic exposure area. Fifty-nine urinary transitional cell carcinoma (TCC) patients from a referral centre in south-western Taiwan and 81 community controls matched on residence were recruited from 1996 to 1999. A questionnaire was administered to obtain arsenic exposure and general health information. Genotypes of p53 codon 72 and GSTT1 were analysed by polymerase chain reaction-restriction fragment length polymerase. The combined variant genotypes (heterozygous or homozygous variant) of p53 codon 72 and GSTT1 null were observed in 29% of cases and in 44% of controls, respectively. In this preliminary study, bladder cancer risk was slightly elevated for subjects carrying the variant genotype of p53 codon 72 or in subjects carrying the GSTT1 null genotype. Variants in p53 codon 72 increased the risk of bladder cancer among smokers. However, the results were not statistically significant and larger confirmatory studies are needed to clarify the role of candidate gene polymorphisms and bladder cancer risk in arsenic exposed populations.

Risk assessment of formaldehyde in typical office buildings in Taiwan.

Our study conducts a series of investigations in five office buildings chosen according to the types of construction, ventilation, and building age. Formaldehyde was measured by continuous photoacoustic Multi-Gas monitor Type 1302 (Brüel & Kjaer). The 8-h average concentrations in working hours were used to estimate the lifetime cancer probability (LCP) and chronic non-carcinogenic hazard index (HI). The carcinogenic effect of formaldehyde estimate by LCP (70 years old) is about 2.06 x 10(-4) to 1.75 x 10(-3) after adjusting their working time. The levels of risk are 100-1000 times of the acceptable carcinogenic risk. A similar trend is observed for the levels of HI calculated. Many studies have suggested that exposure to high levels of formaldehyde may cause nasal cancer and other health effects. Therefore, promoting the labeling system for low emission materials to protect consumers from exposure to excessive emissions and helping the industry to develop low emission materials is evidently urgent and deserves greater efforts.

Climate, traffic-related air pollutants and allergic rhinitis prevalence in middle-school children in Taiwan.

The prevalence of allergic rhinitis, a common respiratory disorder, may be rapidly increasing. Epidemiological studies, however, indicate little about its association with climatic factors and air pollution. The relationship between traffic-related air pollutants and allergic rhinitis in middle-school students was therefore investigated. In a nationwide survey of middle-school students in Taiwan conducted in 1995/1996, the lifetime prevalence of physician-diagnosed allergic rhinitis and typical symptoms of allergic rhinitis were compared with air-monitoring station data on temperature, relative humidity, sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), carbon monoxide (CO) and particulate matter with a 50% cut-off aerodynamic diameter of 10 microm (PM10). A total of 331,686 nonsmoking children attended schools located within 2 km of 55 stations. Mean (range) annual exposures were: CO 853 (381-1,610) parts per billion (ppb), NOx 35.1 (10.2-72.4) ppb, SO2 7.57 (0.88-21.2) ppb, PM10 69.2 (40.1-116.2) microg x m(-3), O3 21.3 (12.4-34.1) ppb, temperature 22.9 (19.6-25.1) degrees C, and relative humidity 76.2 (64.8-86.2)%. The prevalence of physician-diagnosed allergic rhinitis was 28.6 and 19.5% in males and females, respectively, with prevalence of questionnaire-determined allergic rhinitis 42.4 and 34.0%. After adjustment for age, parental education and history of atopic eczema, physician-diagnosed allergic rhinitis was found to be associated with higher nonsummer (September-May) warmth and traffic-related air pollutants, including CO, NOx and O3. Questionnaire-determined allergic rhinitis correlated only with traffic-related air pollutants. Nonsummer warmth and traffic-related air pollution, probably mediated through exposure to common allergens such as dust mites, are possible risk factors for allergic rhinitis in middle-school-aged children.

First Report of Papaya leaf curl virus Infecting Papaya Plants in Taiwan.

Papaya leaf curl disease was first reported in India in 1939 (1). Caused by begomovirus, Papaya leaf curl virus (PaLCV) (2), this disease was discovered in the papaya orchards of southern Taiwan in 2002. Infected papaya developed symptoms such as downward curling of leaves, twisted petioles, vein enation, and stunting. Diseased plants produced small and distorted fruits that tend to fall prematurely. Typical twin virion was observed in the diseased papaya cells by electron microscopy. In addition, our whitefly-transmission test demonstrated that the sweet potato whitefly (Bemisia tabaci) could transmit this virus. For further molecular identification, two opposing primers were selected for the polymerase chain reaction (PCR) detection of PaLCV from the published nucleotide sequences of PaLCV (Genbank Accession No. NC004147) (3). The primer pair, composed of the forward primer 5' -GCT AGA AAT TAT GTC GAA GCG-3' and the reverse primer 5'-TCA ACT ACA ACC TGA GGA AAG C-3', was designed to amplify a PaLCV-specific 1,031-bp fragment containing 774 bp of the coat protein gene open reading frame (CP-ORF) using PCR. Five diseased papaya samples with typical leaf-curl symptoms tested positive in the PCR-based assay with this specific primer pair, whereas five healthy papaya samples tested negative. However, the sequencing results of the PCR product from five PaLCV-infected papayas indicated the CP-ORF of PaLCV in Taiwan (PaLCV-Tw) was somewhat different from PaLCV in India (PaLCV-Id). The DNA sequences (Genbank Accession No. AY183472) of CP-ORF of PaLCV-Tw were 80% identical to those of PaLCV-Id, and their translated amino acid sequences were 77% identical. This indicates that PaLCV-Tw and PaLCV-Id are two different species or strains. References: (1) K. M. Thomas and C. S. Krishnaswamy. Curr. Sci. 8:316,1939. (2) S. Saxena et al. Plant Dis. 82:126, 1998. (3) S. Saxena et al. Biochem. Mol. Biol. Int. 45:101, 1998.

Four-laser scanning confocal system for microarray analysis.

We have constructed a confocal scanner suitable for routine microarray analysis from commercially available parts. We have outlined the details that should be considered when designing such an instrument and listed some of the specific components comprising the system [the full list of system components is available on CD from the corresponding author (D.J.G.) at no charge]. Here, we describe the methods used to test the linearity and sensitivity of the instrument. Performance was evaluated with two commonly used dyes, fluorescein and Cy5. While the instrument had a linear correlation between the dye concentration and fluorescence intensity, the observed deviation from a slope of 1.0 underscores the importance of running multipoint calibration experiments to obtain accurate dye quantitation over the full dynamic range of the scanner. This method has utility in testing commercial instruments in addition to the scanner described here. An array with over 300 spots dyed with Cy3 was scanned with our instrument and a high-end commercial instrument. The agreement between the two instruments was very good over a 1000-fold intensity range. Our scanner is a cost-effective alternative to more costly commercial scanners with similar capabilities.

Exposure assessment to airborne endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide in open style swine houses.

Information is limited for the exposure levels of airborne hazardous substances in swine feed buildings that are not completely enclosed. Open-style breeding, growing and finishing swine houses in six farms in subtropical Taiwan were studied for the airborne concentrations of endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide. The air in the farrowing and nursery stalls as partially enclosed was also simultaneously evaluated. Three selected gases and airborne dusts were quantified respectively by using Drager diffusion tubes and a filter-weighing method. Endotoxin was analyzed by the Limulus amoebocyte lysate assay. Average concentration of airborne total endotoxin among piggeries was between 36.8 and 298 EU/m(3), while that for respirable endotoxin was 14.1-129 EU/m(3). Mean concentration of total dust was between 0.15 and 0.34 mg/m(3), with average level of respirable dust of 0.14 mg/m(3). The respective concentrations of NH3, CO2 and H2S were less than 5 ppm, 600-895 ppm and less than 0.2 ppm. Airborne concentrations of total dust and endotoxin in the nursery house were higher than in the other types of swine houses. The finishing house presented the highest exposure risk to NH3, CO2 and H2S. Employees working in the finishing stalls were also exposed to the highest airborne levels of respirable endotoxin and dust. On the other hand, the air of the breeding units was the least contaminated in terms of airborne endotoxin, dust, NH3, CO2 and H2S. The airborne concentrations of substances measured in the present study were all lower than most of published studies conducted in mainly enclosed swine buildings. Distinct characteristics, including maintaining swine houses in an open status and frequent spraying water inside the stalls, significantly reduce accumulation of gases and airborne particulates.

Fungal exposure of children at homes and schools: a health perspective.

The authors investigated airborne fungal exposure of Taiwanese children at homes and schools-locations where they spent the majority of their time. Pairs of asthmatic and healthy children, matched by age, gender, classes (schools), and residence, participated in the study. Airborne fungal concentrations at homes and schools, and time-activity data of the study subjects were collected. In winter, the indoor geometric mean concentration was 9,672.1 colony-forming units per cubic meter and 4,380.9 colony-forming units per cubic meter in summer. The indoor/outdoor concentration ratio was similar in all homes for both seasons. Fungal concentrations in southern Taiwan were high during both winter and summer. Personal fungal exposure was not statistically different between asthmatic and nonasthmatic children, after adjustment of time-activity patterns. Higher symptom scores were shown for children in homes with higher fungal exposures.

Exposure assessment of indoor allergens, endotoxin, and airborne fungi for homes in southern Taiwan.

This study was undertaken to examine the seasonal variations of domestic Der p 1, Der p 2, and endotoxin on mattress and airborne fungal concentrations in homes of asthmatic and nonasthmatic children in southern Taiwan, where temperature and relative humidity are usually high throughout the year. A group of asthmatic children (10-12 years old) were selected randomly based on a citywide questionnaire survey. The nonasthmatic children were chosen to be in the comparison group by matching in age, gender, and proximity of residence. Environmental sampling of domestic microbes was conducted once a month for a year. Twelve calendar months were grouped into spring, summer, fall, and winter according to weather data (mainly average temperature and humidity) from the Central Weather Bureau. Dust samples from a child's mattress and airborne samples from a child's bedroom were collected and analyzed for allergens of Der p 1 and Der p 2, endotoxin, and fungi respectively. Results show that about 65% of children's mattresses in our region have Der p 1 levels greater than 2 microg/g. It is also apparent that most airborne fungal concentrations found in homes of either asthmatic or nonasthmatic children are higher than the recommended levels of concern. The predominant genera are Cladosporium, Aspergillus, Penicillium, Alternaria, and yeast. In addition, seasonal effects seem to be a critical factor for the concentrations and distributions of domestic endotoxin in these study homes. The implication of long-term exposure to these high levels of environmental microbes and how their effects vary with seasons remain to be further characterized.