Biomedical subjects
Publications and source records attributed to Y L Guo.
A high incidence of bladder cancer has been documented in an area of chronic arsenic (As) exposure. This study investigates the characteristics of As-associated (n = 49) and other (n = 64) bladder cancers. A higher histological grading was observed for the As-exposed tumours (P = 0.04), but no other difference in pathobiological features or prognosis was found between the two groups.
The cases of three patients with acute pulmonary oedema caused by inhalation of fumes from heated polytetrafluoroethylene (PTFE) in a plastic factory are described. One patient died from profound hypoxaemia and shock shortly after admission, and the other two patients survived after medical treatment. This is the first report of fatal pulmonary oedema in a worker exposed to PTFE heated in a plastic extruding operation. From this observation, it appears that inhalation exposure to pyrolytic products from polytetrafluoroethylene can cause fatal respiratory complications. Special precautions are warranted in this kind of operation to prevent workers from being exposed to these substances.
Nutritional survey was conducted in 1994 in Tainan City, southern Taiwan. Total food duplicate samples were collected from 52 women volunteers. Clinical examinations, anthropometry, hematology and serum biochemistry were also conducted. The intakes of nutrients were estimated from the weights of food items in reference to the standard food composition tables for Taiwanese. On average, the participants took 1,973 kcal energy, 69 g protein, 73 g lipid and 269 g carbohydrate per day. Animal-based foods accounted for 49% and 36% of protein and lipid sources, respectively, but fish and shellfish contributed only 11% for protein and essentially nil for lipid. Lunch was the most substantial meal of the day. When classified by age (i.e., 22-29, 30-39 and 40-66 year-old groups), no age-related difference was detected among the three groups in all nutrients except for crude fiber. Comparison with recommended dietary allowance (RDA) for Taiwanese, the insufficiency ratios were more than 50% for minerals (i.e., Fe and Ca) and vitamins (except for vitamin C). Excess in the lipid energy ratio (> 30%) was observed in 60% of the study population. In agreement with this high lipid intake, 17% of the participants had BMI of > 25, and triglyceride levels were elevated (> 150 mg/100 ml) in 27%. There were no anemic case despite the low Fe intake (14 mg/day).
For the purpose of searching for new drug with high potency and simple chemical structure, the dominant conformation and structural parameters of Guan-Fu base (GFA) molecule were modelled and calculated with a SGI-4D 25G computer. The propanediolamine chain in GFA might be considered to be a pharmacophore responsible for the bioactivity and the configuration of the chain seemed important. Thus, thirteen compounds of (erythro)-p-x-PhCHOHCHOHCH2NHR(x = H, I1-7; X = NO2, II1-6) were prepared. Among them, 10 compounds showed antiarrhythmic effect on aconitine-induced arrhythmia in rats. The ED50(to stop VT) of I2 and ED50(to stop VP) of I3 were shown to be comparable with those of GFA. In the synthesis, no stereoselectivity was found in the Prevost reaction with allylamine analogues (a1-7). After a1-7 were acetylated, the erythro type products(I1-7) were obtained.
We report the isolation and characterization of a protein Ser/Thr phosphatase from highly purified pea nuclei. In subnuclear fractions, more than 75% of Ser/Thr protein phosphatase activity was associated with the chromatin fraction, whereas the other 25% was in the nuclear membrane/nucleoplasmic fraction when phosphorylase a was used as a substrate. The enzyme was purified approx. 2750-fold to a specific activity of approx. 4000 nmol/min per mg. The molecular mass of the enzyme was 34 kDa as estimated by molecular sieve chromatography, and approx. 40 kDa as estimated by SDS/PAGE. The phosphatase was inhibited by okadaic acid with an IC50 of approx. 15 nM, by rabbit muscle inhibitor 2 with an IC50 of approx. 10 nM, and by microcystin-LR with an IC50 of approx. 0.05 nM. The enzyme did not require Ca2+, Mg2+ or Mn2+ for its activity; instead, these cations showed some inhibitory effects. It was inhibited by NaF or citrate but not by tartrate, molybdate or vanadate under the conditions tested. Its sensitivities towards the various phosphatase inhibitors and its substrate specificity were very similar to those characteristic of the type I Ser/Thr protein phosphatases well studied in animal systems. The enzyme was able to selectively dephosphorylate a 92 kDa nuclear protein that had been phosphorylated by one or more endogenous protein kinases.
Venous blood samples, 24-h total food duplicate samples, and rice samples were collected from 52 adult non-smoking women in the city of Tainan, southern Taiwan, in 1994, and analyzed for cadmium (Cd) and lead (Pb) by wet-digestion followed by graphite furnace atomic absorption spectrophotometry. Daily dietary intake was 10 micrograms for Cd and 22 micrograms for Pb as geometric means, of which Cd and Pb in rice accounted for 34% and 1.4% of daily Cd and Pb intakes, respectively. The counterpart values for blood were 1.11 ng/ml and 44.5 ng/ml for Cd and Pb, respectively. International comparison with recently published data suggests that the exposure to Cd in Tainan should be among the lowest in the world.
We designed two sets of oligonucleotide primers to amplify the immunoglobulin heavy- and light-chain variable-region genes from genomic DNA by polymerase chain reaction (PCR). The genomic DNA was extracted from hybridoma BDI-1 cells, which secreted a monoclonal antibody (mAb) against human bladder carcinoma. The primers contained special restriction sites that allowed the variable-region genes to be easily cloned for sequencing and expression. The recombinants were sequenced by Sanger's method. It was proved that the full lengths of the VH and VK genes were 366 and 324 bp, respectively. Compared with other published sequences, the VH gene was a member of mouse heavy-chain VH subgroup II and originated from the rearrangement of VH, Dsp2.2 and JH4. The VK gene was VK subgroup IV and from VK and JK4. The VH and VK genes was inserted expression vector pWAI80. By inducement, the ScFv antibodies were expressed and secreted from Escherichia coli. Binding activities against the bladder carcinoma cells were detected. We suggest that ScFv antibody recognized the antigen specifically.
The purpose of this study was to investigate environmental lead exposure in the general Taiwanese population. A total of 8828 Taiwanese adults selected by a multistage sampling method were investigated. Characteristics of the participants were ascertained by questionnaire and 10 ml venous blood was drawn by public health nurses. The blood specimens were distributed to six laboratories for blood lead level (BLL) measurement. A quality control program was applied during the analysis of the BLLs in order to improve precision and accuracy. The arithmetic mean BLL of the 8828 Taiwanese adults was 7.70 +/- 5.23 micrograms/dl, with a maximal level of 69.1 micrograms/dl. The median was 6.5 micrograms/dl and the 90th percentile was 14.0 micrograms/dl. After logarithmic transformation, the geometric mean was 1.84 +/- 0.67 microgram/dl. This study also found that elevated BLLs were associated with certain personal characteristics, i.e., gender, ethnic group, and education level; life-style factors, such as smoking, alcohol consumption, Chinese herbal drug consumption, milk consumption, and sources of drinking water; residential location, i.e., level of urbanization; and occupational history of lead exposure. However, age, floor level of residence, distance from house to road, and betel nut consumption were not associated with elevated BLLs. These results showed that BLLs in the Taiwanese population were not higher than those in developed and developing countries. Most of the influencing factors were also found in other studies; however, local factors such as ethnic group, Chinese herbal drug consumption, and sources of drinking water are important considerations in Taiwan when examining ways to prevent overexposure to lead in the general population.
OBJECTIVES: Agricultural workers are known to have occupational skin diseases. The prevalence and pattern of skin diseases are unknown in Taiwanese fruit farmers. The objective of this study is to determine the work exposure, prevalence of skin diseases, and sensitivity to common skin allergens and agricultural chemicals in fruit farmers of southern Taiwan. METHODS: 122 fruit farmers who regularly prepared and sprayed pesticides and a group of 63 printing press workers with no known exposure to pesticides were examined and patch tested with common skin allergens and agricultural chemicals. The farmers were also interviewed for their work habits, use of protective clothing, and exposure to pesticides. RESULTS: Most farmers reported regular use of hat, boots, and mask, but not gloves, raincoat, and goggles. This resulted in frequent skin contact with pesticides especially on the hands and face. About 30% of farmers had hand dermatitis, and more than two thirds had pigmentation and thickening on the hands. Fungal infection of the skin was noted in a quarter of subjects. By patch test, farmers and the printing press workers had a similar rate of sensitivity to common skin allergens. 40% of farmers were sensitive to agricultural chemical allergens, which was about twofold higher than that of the comparison group. Farmers were most frequently sensitive to Captofol, Folpet, and Captan which were associated with dermatitis on the volar aspects of the hands. CONCLUSIONS: Fruit farmers in southern Taiwan had a high prevalence of skin diseases related to use of pesticides, and appropriate protective measures and work practices should be taken to prevent such problems.
Phosgene, a toxic gas widely used as an industrial chemical intermediate, is known to cause life-threatening latent noncardiogenic pulmonary edema. Mechanisms related to its toxicity appear to involve lipoxygenase mediators of arachidonic acid (AA) and can be inhibited by pretreatment with drugs that increase adenosine 3',5'-cyclic monophosphate (cAMP). In the present study, we used the isolated buffer-perfused rabbit lung model to investigate the mechanisms by which cAMP protects against phosgene-induced lung injury. Posttreatment with dibutyryl cAMP (DBcAMP) was given 60-85 min after exposure by an intravascular or intratracheal route. Lung weight gain (LWG) was measured continuously. AA metabolites leukotriene (LT) C4, LTD4, and LTE4 and 6-ketoprostaglandin F1 alpha were measured in the perfusate at 70, 90, 110, 130, and 150 min after exposure. Tissue malondialdehyde and reduced and oxidized glutathione were analyzed 150 min postexposure. Compared with measurements in the lungs of rabbits exposed to phosgene alone, posttreatment with DBcAMP significantly reduced LWG, pulmonary arterial pressure, and inhibited the release of LTC4, LTD4, and LTE4. Intratracheal administration of DBcAMP was more effective than intravascular administration in reducing LWG. Posttreatment also decreased MDA and protected against glutathione oxidation observed with phosgene exposure. We conclude that phosgene causes marked glutathione oxidation, lipid peroxidation, release of AA mediators, and increases LWG. Posttreatment with DBcAMP attenuates these effects, not only by previously described inhibition of pulmonary endothelial or epithelial cell contraction but also by inhibition of AA-mediator production and a novel antioxidant effect.
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Retroviral vectors were used to introduce the wild-type p53 gene into human bladder cancer cell lines BIU-87 and EJ, which express endogenous wt-p53 gene and have a mutation in H-ras gene. The expression of the exogenous wt-p53 gene in cells suppresses the growth of the bladder cancer cells in standard culture and in soft agar and blocks the cell cycle progression in G1. The BIU-87 and EJ cells developed tumors with average volumes of 6.53 cm3 and 6.61 cm3 in nude mice in 9 weeks after inoculation, while the cells transduced with wt-p53 gene failed to form tumors. The expression of H-ras gene in bladder cancer cells was reduced at mRNA level. These results suggest that the overexpression of the wt-p53 gene suppresses the expression of mutant H-ras gene and inhibits the tumor cell growth in vivo and in vitro.
A pea (Pisum sativum L.) nuclear enzyme with protein tyrosine phosphatase activity has been partially purified and characterized. The enzyme has a molecular mass of 90 kD as judged by molecular sieve column chromatography and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Like animal protein tyrosine phosphatases it can be inhibited by low concentrations of molybdate and vanadate. It is also inhibited by heparin and spermine but not by either the acid phosphatase inhibitors citrate and tartrate or the protein serine/threonine phosphatase inhibitor okadaic acid. The enzyme does not require Ca2+, Mg2+, or Mn2+ for its activity but is stimulated by ethylenediaminetetraacetate and by ethyleneglycolbis(beta-aminoethyl ether)-N,N'-tetraacetic acid. It dephosphorylates phosphotyrosine residues on the four different 32P-tyrosine-labeled peptides tested but not the phosphoserine/threonine residues on casein and histone. Like some animal protein tyrosine phosphatases, it has a variable pH optimum depending on the substrate used: the optimum is 5.5 when the substrate is [32P]tyrosine-labeled lysozyme, but it is 7.0 when the substrate is [32P]tyrosine-labeled poly(glutamic acid, tyrosine). It has a Km of 4 microM when the lysozyme protein is used as a substrate.
Occupational skin disease is one of the most common occupational diseases. The hand is the most frequent site of involvement in occupational skin disease. We interviewed and examined patients seen in the Contact Dermatitis Clinic of the National Taiwan University Medical Center, a tertiary referral center in Taipei City. For patients suspected of having allergic skin diseases, patch testing was carried out using the European standard series and suspected allergens. Occupational hand dermatitis (OHD) was diagnosed according to medical history, work exposure, physical examination, and patch test findings. 36% of patients seen were diagnosed as having OHD. Electronics, hairdressing, medical, chemical, and construction were the most important industries causing OHD. In the 164 patients with OHD, 58.5% had irritant contact dermatitis (ICD) and 41.5% allergic contact dermatitis (ACD). Dorsal fingers, nail folds, and dorsal hands were most frequently involved in patients with ACD; dorsal fingers, volar fingers and fingertips were most frequently involved in those with ICD. Using logistic regression analysis, we were able to identify the most important clinical presentations that predicted the types of OHD, ACD versus ICD. Patients with atopic history and palm involvement were more likely to have ICD, and those with nail fold involvement more likely to have ACD. In patients with ACD, the most important allergens were dichromate, nickel, cobalt, fragrance mix, epoxy resin, thiuram mix, and p-phenylenediamine. In this study, we identified the important industries and causal agents for OHD. Future preventive measures focused on these industries and agents to reduce OHD will be warranted.
This article reviews the findings in children exposed to various levels of polychlorinated biphenyls (PCBs) and related compounds in utero and early postnatally. Yu-Cheng ("oil-disease") mothers were Taiwanese women exposed to PCBs and their heat-degradation products from the ingestion of contaminated rice oil in 1979. Children of these mothers were born growth retarded, with dysmorphic physical findings, and delayed cognitive development compared with unexposed children. In this article, findings in Yu-Cheng children born between 1978 and 1985 are summarized and compared with two other well-documented cohorts of children prenatally exposed to different levels of PCBs. Results of the investigation in Yu-Cheng children will provide important information about the toxicities, health effects, and mechanisms of PCB/PCDF exposure and demonstrate that the developing human is more sensitive than the adult to the toxic effects of these chemicals.
A clinical trial using the combination of rice bran fiber (RBF) and cholestyramine (CHO) was carried out on Yu-Cheng patients in 1993-1994. By the analysis of blood and stool samples collected from the patients before and after (or during in the case of stool), it was verified that the administration of RBF and CHO is effective for excretion of polychlorinated biphenyl (PCB) (p < 0.05) and polychlorinated dibenzofuran (PCDF), especially 2, 3, 4, 7, 8-pentachlorodibenzofuran (p < 0.05). However, the degree of effectiveness varied upon individual patients from 60 to 160% for 2, 3, 4, 7, 8-pentachlorodibenzofuran, from 30 to 110% for 1, 2, 3, 4, 7, 8-hexachlorodibenzofuran and from 50 to 190% for PCB, respectively.
Levels of PCDDs, PCDFs and coplanar PCBs were measured in the blood and stool obtained from seventeen patients with Yu-Cheng in Taiwan. The average total concentrations of PCDDs, PCDFs and coplanar PCBs in the blood collected from Yu-Cheng patients in January 1993 and August 1994 were 590 and 570 pg Toxic Equivalents (TEQs)/g lipid, respectively. The concentrations of PCDDs, PCDFs and coplanar PCBs in the blood of patients were 21, 540 and 10 pg TEQs/g fat, respectively. On the other hand, the fecal excretion of PCDDs, PCDFs and coplanar PCBs were 26, 720 and 15 pg TEQs/day, respectively. The composition of congeners in the feces was quite similar to the one in the blood. The half lives were estimated as 9.1 and 8.6 years for 2, 3, 4, 7, 8-pentachlorodibenzofuran and 1, 2, 3, 4, 7, 8-hexachlorodibenzofuran based on fecal excretion, respectively.
The purpose of this study was to investigate the environmental lead exposure of the general population in Taiwan. A total of 2919 residents of Taiwan were selected by multistage sampling methods. The participants were characterized by questionnaires and 10 ml venous blood was collected for blood lead measurement. A quality assurance/quality control program was designed during the analysis of blood lead levels. The mean blood lead level of 2719 residents without occupational lead exposure was 8.29 +/- 5.92 micrograms/dl. After adjustment for age and sex distribution to the Taiwan general population, the mean blood lead level was 8.10 micrograms/dl. Adjusted for an 11% underestimation of blood lead levels among the six laboratories, the mean blood lead level was estimated to be 8.99 micrograms/dl. This study also found that blood lead levels were associated with personal characteristics, i.e., gender, ethnic group, education level; lifestyle factors, i.e., smoking, alcohol consumption, sources of drinking water; and residential location, i.e., levels of urbanization, distance of house from the road. However, age, floor of residence, milk consumption, betel nut consumption, and Chinese herbal drug consumption were not found to be associated with blood lead levels. These results show that blood lead levels in Taiwan residents were not higher than in most developed and developing countries. Environmental lead pollution does not seem to be a serious problem in Taiwan.