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Biomedical subjects

S F Chou

Publications and source records attributed to S F Chou.

9 recordsLinked to original sources
PubMed2001

Pesticide storage and release in unsaturated soil in Illinois, USA.

The chemical fate and movement of pesticides may be subject to transient storage in unsaturated soils during periods of light rainfall, and subsequent release into shallow groundwater by increased rainfall. The objective of this study was to conduct field-scale experiments to determine the relative importance of transient storage and subsequent release of agrichemicals from the vadose zone into potential aquifers. Two field-scale experiments were conducted under a rain exclusion shelter. In the 1x experiment, atrazine and chlorpyrifos were applied at application-rate equivalents (1.6 kg ha(-1) and 1.3 kg ha(-1), respectively). In the 4x experiment, atrazine was applied in an amount that was four times greater than that usually applied to fields (6.7 kg ha(-1)). Water was either applied to simulate rain or withheld to simulate dry periods. In the 1x experiment, atrazine was detected in the water samples whereas chlorpyrifos was not detected in the majority of the samples. The dry period imposed on the treatment plot did not appear to result in storage of the chemicals, whereas the wet period resulted in greater leaching of atrazine, although the concentrations remained less than the Maximum Contaminant Level of 3 microg L(-1). Both chemicals were detected in soil samples collected from a 20- to 30-cm depth, but it appeared that both chemicals dissipated before the field experiment was concluded. It appeared that the one-time application of atrazine and chlorpyrifos at the label rates did not result in a sufficient mass to be stored and flushed in significant concentrations to the saturated zone. When atrazine was applied at 4x and a longer drought period was imposed on the treatment plot, the resulting concentrations of dissolved atrazine were still less than 3 microg L(-1) . Atrazine was detected in only the near-surface (0 to 15 cm) soil samples and the herbicide dissipated before the onset of the dry period in the treatment plot. The results of this field study demonstrated that atrazine and chlorpyrifos were not sufficiently persistent to be stored and then released in significantly large concentrations to the saturated zone. The dissipation half-life of atrazine in the 4x application was about 44 days. This study, in addition to others, suggested that atrazine may be less persistent in surface soil than has been generally reported.

Atrazine↗
PubMed2001

Monoclonal and polyclonal antibodies against human ferritin, a nonspecific tumor marker.

The aim of this study was to produce monoclonal and polyclonal antibodies against a nonspecific tumor marker, human ferritin. Hyperimmune ICR mice produced polyclonal antibodies after injection with 0.5 mL pristane, and were injected with NS-1 myeloma cells 2 weeks later. Hyperimmune Balb/c mice were used for the production of monoclonal antibodies (MAbs). Mice were immunized four times, given a final boost, and their spleen cells were collected and fused with NS-1 myeloma cells under the presence of PEG 1500. The fused cells were then selected in the HAT-RPMIX medium. Anti-ferritin antibody-secreting hybridoma cell lines with high titer were cloned by enzyme-linked immunoadsorbent assay (ELISA) and then subcloned by limiting dilution in 15% fetal bovine serum (FBS) HT-RPMIX medium. Five murine hybridoma-producing antiferritin MAbs were obtained and designated 1AD11F9, 1AD11E11, 2AD11D2, 2AD11A5, and 3AD11G8. Isotypes of these MAbs were identified as IgM heavy chain and kappa light chain. Hitrap Protein A and Hitrap IgM purification column were used for the purification of polyclonal and monoclonal antibodies, respectively.

Animals↗
PubMed1996

Microbiologic assay for detection of antimicrobial agents in urine.

Antimicrobial therapy can be a confounding factor in the diagnosis of urinary tract infection and is not always reported to laboratories by physicians. We developed a microbiologic assay for screening urine specimens for antimicrobial agents. Bacillus stearothermophilus was used as the indicator bacteria. A total of 1,921 urine specimens from three hospitals in Taiwan were screened using this assay. Of the samples assayed, 1,293 were positive for antimicrobial agents. Agreement between information provided by physicians and laboratory findings was 68.5% (419/612). In the presence of antimicrobial agents in the urine samples, the isolation of yeasts and Pseudomonas aeruginosa increased dramatically, from 4.5 to 19.5% and 4.2 to 13.2%, respectively. Additionally, Escherichia coli was more resistant to gentamicin (75.3% vs 48.7%, p < 0.0001), norfloxacin (85.2% vs 64.6%, p = 0.0006) and co-trimoxazole (58.5% vs 35.5%, p = 0.0018). In view of the high rate of occurrence of antimicrobial agents in urine specimens and the lack of information provided by most physicians to laboratories, a screening method to detect the presence (or absence) of antimicrobials in urine specimens may be a useful tool particularly in areas such as Taiwan where antimicrobial agents are commonly abused.

Anti-Bacterial Agents↗
PubMed1989

[The ratios and kinds of clinical bacteria isolated in Taiwan's large-size hospitals].

The prevalence of clinical bacteria, as isolated from Linko Chang-Gung Memorial Hospital (2,300 beds) in the period January 1985 to December 1986 and from Taipei Veterans General Hospital (2,300 beds) during the period January 1986 to December 1986, was analyzed with the following findings: (i) The isolation ratio of anaerobic and aerobic or facultative bactria during the period of investigation were 7.8% (5,513/70,799) and 92.2% (65,286/70,799), respectively. (ii) Of the total aerobic or facultative isolates from the two hospitals, 32.9% (21,510/65,286) were Gram positive cocci and bacilli, 67.1% (43,776/65,286) were Gram negative cocci and bacilli. (iii) Of these Gram-negative bacilli, 65.2% (28,490/43,675) were Enterobacteriaceae were Enterobacteriaceae and glucose fermentative Gram negative bacilli, 32.0% (13,984/43,675) were glucose nonfermentative Gram negative bacilli, and 2.7% (1,200/43,675) were fastidious Gram negative bacilli. (iv) The more common species among the members of Enterobacteriaceae were Escherichia coli 35.7% (10,163/28,490), and Klebsiella pneumoniae 18.2% (5,186/28,490). The other common species included Enterobacter cloacae, Proteus mirabilis, Serratia marcescens, Morganella morganii, Citrobacter freundii and Proteus vulgaris. The frequencies of Salmonella species and Shigella species in these two large hospitals were up to 1.6% (456/28,490) and 0.5% (149/28,490), respectively. The most common isolate among other glucose fermentative Gram negative bacilli was Aeromonas hydrophila 3.0% (843/28,490). The finding of 0.1% (11/28,490) Vibrio alginolyticus was considered as clinically significant in Taiwan. (v) Of these glucose nonfermentative Gram negative bacilli, 69.4% (9,704/13,984) were Pseudomonas aeruginosa, 18.9% (2,637/13,984) Acinetobacter species, 10.8% (1,516/13,984) Pseudomonas species. (vi) The most common bacteria among fastidious Gram negative bacilli was Haemophilus influenzae, 96.2% (1,154/1,200). (vii) Of these Gram negative cocci, 59.4% (60/101) was Neisseria gonorrhoeae and 6.9% (7/101) N. meningitidis. (viii) The more common isolates of Gram positive bacilli included Bacillus species and Corynebacterium species (diphtheroids). (ix) Of these Gram positive cocci, the isolation rates of Staphylococcus species and Streptococcus species were 54.6% (10,838/19,827) and 45.4% (9,002/19,847), respectively. The most common isolate among Gram positive cocci was Staphylococcus aureus, 30.2% (5,994/19,847); the next, enterococcus, 24.9% (4,936/19,847); then S. epidermidis, 22.2% (4,390/19,847). The less common isolates were Streptococcus pyogenes 1.1% (212/19,847) and S. pneumoniae, 1.7% (329/19,847).(ABSTRACT TRUNCATED AT 400 WORDS)

Bacteria↗
PubMed1978

Field concentrations and persistence of polybrominated biphenyls in soils and solubility of PBB in natural waters.

Soil samples were collected from 28 fields which had received manure from Michigan's most highly contaminated dairy herds. The number of fields in each concentration range of PBB in soil were: 2, not detectable; 15, 0.0 to 8.0 ppb; 6, 14-102 ppb, and 5, 153 to 371 ppb. Plant tissue sampled from the 10 most highly contaminated fields contained no detectable PBB. No evidence of significant degradation of PBB was noted after 1 year incubation in soil. When 14C hexabromobiphenyl and heptabromobiphenyl isomers were incubated in soil less than 0.2% of the 14C was volatilized. Also gas chromatographic analysis of soil extracts showed no difference in recovery of the six major PBB isomers between sterilized and nonsterilized soil. Analysis of these extracts by thin layer chromatography and autoradiography showed no 14C-PBB intermediates. Photodegradation products of the major hexa- and heptabromobiphenyl isomers showed more but still minor (approximately 3%) biodegradation in soil. Much of the photodegradation products appeared bound to soil, since these products could not be extracted from soil. Photodegradation does not appear to be a significant fate of PBB in manures spread on fields since no change was noted in the relative concentrations of isomers in soil samples from our field survey. Studies with distilled, tap, river, and soil waters showed that PBB solubility was markedly influenced by water composition.

Animals↗
PubMed1978

Absence of plant uptake and translocation of polybrominated biphenyls (PBBs).

Studies of polybrominated biphenyl (PBB) uptake by plants have been conducted in hydroponic solutions and in greenhouse experiments with soil. Autoradiograms of corn and soybean seedlings grown in hydroponic solutions showed no translocation of 14C-PBB from 14C-PBB-treated solutions to plant tops or within the leaf from 14C-PBB-treated spots on the upper leaf surface. A significant portion of the 14C-PBB associated with the roots was removed when the roots were dipped in acetone. Three root crops (radishes, carrots, and onions) were grown in two soils, each treated with a mixture of FireMaster BP-6 (PBB) and 14C-PBB to achieve final concentrations of 100 ppm and 100 ppb. All roots showed more PBB when grown in the soil with the lower clay and organic matter content than they did when grown in the soil with more clay and organic matter. In the latter soil (clay loam) no PBB was detected in any roots from the 100 ppb treatment. More PBB was associated with roots of carrot than of radish or onion. Corn leaf whorls containing dust from a PBB contamination soil and washed radishes from a heavily contaminated garden showed no PBB.

Biphenyl Compounds↗
PubMed1976

Concentric nuclear inclusions.

Membrane bound concentric lamellar inclusions were found in the nuclei of pancreatic acinar cells of a patient with multiple primary neoplasms and in the parotid acinar cells of a patient with systemic lupus erythematosus. It is proposed that these inclusions form from rough cisternae sequestered in the nucleus.

Adenoma, Islet Cell↗