Medical and non-medical correlates of carpal tunnel syndrome in a Taiwan cohort of one million.

BACKGROUND: Carpal tunnel syndrome (CTS), with unclear etiology, is the most common entrapment neuropathy. Its occurrence is related to lots of medical and non-medical conditions with uncertain causality. With a large population, we characterized selected demographical and clinical factors to add more information on CTS-correlated factors and new insight into future CTS prevention. METHODS: A national insurance claim dataset of one million enrollees in Taiwan was used to identify 15 802 patients with CTS and 31 604 randomly selected controls, during a period of 7 years starting 1 January 2000. Statistical association with CTS was determined for five sociodemographic and nine medical factors. RESULTS: Patients were predominantly women (65.6% vs. 47.7% in the control group) and older (40 and above, 62.6% vs. 36.2%). Rheumatoid arthritis was found to be the most significant comorbidity associated with CTS, followed by gout, hypertension, diabetes, obesity, uremia, and acromegaly. For younger group age ≤39, the association of these comorbidities was stronger, and hypothyroidism and vitamin B(6) deficiency were additional comorbidities. Aging appears to reduce the relative impact of the diseases commonly associated with CTS as the possible risk factors. CONCLUSIONS: Identification of the CTS correlates in younger group would be of greater value in timely detection and treatment for these diseases. Correcting these disorders may aid in removing possible causes of CTS. This is the first report on the effect of aging on probable CTS risk factors. How factors associated with aging contribute to the development of CTS remains to be determined.

Aflatoxicol: major aflatoxin B1 metabolite in rat plasma.

Aflatoxicol, a carcinogenic metabolite of the foodborne carcinogen aflatoxin B1 previously known only as a bioreduction product in vitro, was identified as the major aflatoxin metabolite in the plasma of Sprague-Dawley rats, a susceptible species, that had been doses orally or intravenously with aflatoxin B1 labeled with carbon-14. Alfatoxicol, however, was not detected in the plasma of similarly dosed mice and monkeys, which are both resistant to aflatoxin B1-induced cardinogenesis. The formation of aflatoxicol both in vitro and in vivo may be an indicatory of species sensitivity to aflatoxin-induced carcinogenesis and may be useful in the prediction of human susceptibility.

Toxicological analysis points to a lower tolerable daily intake of melamine in food.

Intensified food safety concern over melamine has prompted national authorities to assess its tolerable daily intake (TDI) for protection of general population including young children. TDI is calculated by dividing a no-observed-adverse-effect level (NOAEL) by a safety factor (SF). Based on appropriate choices of values, the US Food and Drug Administration determined two TDI values in the unit of mg per kg body weight per day as first 0.63 and then 0.063, while the World Health Organization, 0.5 and then 0.2, as a result of increasing the SF values in calculation. We used a similar procedure, with judicious selection of pertinent values, to obtain a TDI of 0.0081. Arguments in support of this lower TDI value were provided to alert the international community.

Hepatocarcinogenicity of sterigmatocystin and versicolorin A to rainbow trout (Salmo gairdneri) embryos.

Versicolorin A (VA) and sterigmatocystin (ST) are biosynthetic precursors of aflatoxin B1 (AFB1). The carcinogenicity of these compounds relative to AFB1 was determined with the use of rainbow trout (Salmo gairdneri) embryo exposure. Exposure of 14-day rainbow trout embryos to a 0.5-ppm aqueous suspension of ST for 1 hour produced a 13% incidence of hepatocellular carcinomas among survivors 1 year later. Similar exposure of trout eggs to a 0.5-ppm solution of AFB1 produced a 53% incidence among survivors. Subsequent exposure of 21-day rainbow trout embryos to 5- and 25-ppm solutions of VA resulted in hepatocellular carcinoma incidences among survivors of 42 and 68%, respectively, at 12 months. A 0.5-ppm AFB1 positive control group had a 68% incidence among survivors of hepatocellular carcinomas at 1 year. These results established the carcinogenicity of VA for the first time and confirmed previous reports of ST carcinogenicity. Both compounds were of sufficient potencies to warrant caution as possible human health hazards.

Carcinogenic response of rainbow trout (Salmo gairdneri) to aflatoxin Q1 and synergistic effect of cyclopropenoid fatty acids.

Aflatoxin Q1 (AFQ1), the major microsomal biotransformation product of aflatoxin B1 (AFB1) formed in vitro by monkey and human liver preparations, was fed to rainbow trout (Salmo gairdneri) in a semipurified diet at levels of 20 ppb for 1 year and 100 ppb for 10 months. As a test for carcinogenicity in hatched fish, it was also used at 1 ppm in a water solution and exposed for 1 hour to fertile trout eggs. The 20-ppb dietary exposure and 1-ppm egg exposure failed to elicit a carcinogenic response; however, the 100-ppb dietary exposure produced a 10.6% incidence of hepatocellular carcinomas at the end of 1 year. Administration of 50 ppm methyl sterculate, a cyclopropenoid fatty acid, in combination with 100 ppb AFQ1 resulted in a synergistic tumor response similar to that previously noted with administration of AFB1 plus aflatoxin M1. The tumor incidence was 89.1% in the fish on the combined diet. These results indicated that AFQ1 was approximately 100 times less carcinogenic than was AFB1. This comparison of carcinogenic potencies was very similar to the comparison of the relative mutagenicities of the two compounds in the Ames bacterial mutagen assay system.

Metabolism of aflatoxin B1 in the upper airways of the rabbit: role of the nonciliated tracheal epithelial cell.

Short-term tracheal explant cultures from the rabbit were used to study the metabolism of the carcinogen aflatoxin B1 (AFB1) and to determine the cell types that are susceptible to damage by AFB1 and their relative contents of monooxygenase enzymes. Tracheas were cultured in serum-free medium for 0.5-24 h with 0.7 microM [3H]AFB1, and metabolism was measured by determining the level of binding of the carcinogen to DNA and by the release of metabolites into the medium. The binding of aflatoxin B1 was time dependent and appeared to peak at 12 h in culture. In addition, the metabolites aflatoxicol, aflatoxin M1, and aflatoxin Q1 were produced by the explants. Ultrastructural evaluation of cultured tracheas showed degenerative changes exclusively in nonciliated secretory cells after 4 h in culture. Extensive nonciliated secretory cell necrosis was evident by 12 h. Ciliated cells did not show degenerative changes until 12 h and appeared much more viable after 24-h exposure to AFB1 relative to the nonciliated cells. Tracheal sections stained to demonstrate rabbit lung cytochrome P-450, Forms 2 and 5, and cytochrome P-450 reduced nicotinamide adenine dinucleotide phosphate reductase by an immunoperoxidase technique showed intense staining selectively within nonciliated cells. In total, the data revealed that: (a) rabbit tracheal explants are able to metabolize aflatoxin B1; (b) the nonciliated secretory cell population in this tissue is the target cell for cytotoxicity of this carcinogen; and (c) as is the case in the more distal airways, the nonciliated epithelial cells appear to have a high content of components of the pulmonary cytochrome P-450 monooxygenase system, which may be an important factor in the susceptibility of these cells and this region of the airways to suspected airborne carcinogens.

Carcinogenicity of dietary aflatoxin M1 in male Fischer rats compared to aflatoxin B1.

Aflatoxin M1 (AFM), an hydroxy metabolite of the potent carcinogenic mycotoxin aflatoxin B1 (AFB) is frequently found in milk and other dairy products. Sufficient amounts of AFM were produced to study the carcinogenicity of this compound. AFM was fed to male Fischer rats starting at 7 weeks up to 21 months of age. Agar-based semisynthetic diets contained 0.0, 0.5, 5.0, and 50.0 micrograms/kg of AFM or 50 micrograms/kg of AFB. Hepatocellular carcinomas were detected in two of 37 rats and neoplastic nodules were found in six of 37 rats fed 50 micrograms/kg AFM between 19 and 21 months. No nodules or carcinomas were observed in the lower AFM dose groups. Nineteen of 20 rats fed a diet containing 50 micrograms/kg of AFB developed hepatocellular carcinomas by 19 months of age. Carcinogenic potency of the aflatoxins was reflected by morphometric quantitation of foci detected in hematoxylin and eosin stained sections. Three rats fed the diet containing 50 micrograms/kg AFM developed intestinal carcinomas. None were observed in other groups. Under the conditions of this experiment AFM was found to be a weak hepatic carcinogen compared to AFB and to possess intestinal carcinogenicity.

Toxicity identification evaluation (TIE) of pore water of contaminated marine sediments collected from Hong Kong waters.

Marine sediment can function both as a source and as a sink of marine chemical contaminants. The toxicity of contaminated marine sediment can be assessed by toxic evaluation of its pore water, the inter-particle water of sediment, because toxicants in the pore water may be bioavailable to marine organisms. In this study, the toxicity identification evaluation (TIE) was performed to identify the major toxicants in the pore water of marine sediment collected in Hong Kong waters. In Phase 1 TIE, the suspected toxicants were characterized as anions or organic compounds that are either oxidizable or filterable in alkaline medium. In Phase 2 TIE, the suspected toxicants were identified as sulfide (S(2-)) based on the reduction of toxicity due to lowering of sulfide concentrations by experimental manipulations. The mass balance and spiking analyses in Phase 3 confirmed that S(2-) was one of the major toxicants and that some non-toxic unknown compounds measured by LC-MS, which was removed by C18 solid phase extraction, enhanced the toxicity of S(2-) in the pore water samples.

Determination of interactions between human thrombopoietin and its receptor MPL by yeast two-hybrid system and affinity biosensor.

The binding of human thrombopoietin to the extracellular domain of its receptor MPL prompts a cascade transduction of intracellular signals, leading to the development of megakaryocyte precursors and the production of circulating platelets. We have used a yeast two-hybrid system to reveal, via in vivo interactions between different deletion constructs of MPL and thrombopoietin, that the extracellular subunit 1 of MPL is the ligand binding site and the N-terminal domain of thrombopoietin alone is sufficient for the binding. The extracellular portion of MPL was heterologously expressed in E. coli and its specific affinity with thrombopoietin was visualized in vitro by resonance mirror biosensor technique.

Cytotoxicity assessment of Ma-huang (Ephedra) under different conditions of preparation.

Ma-huang is a traditional Chinese medicinal herb derived from EPHEDRA: sinica Stapf and other EPHEDRA: species, used to treat asthma, nose and lung congestion, and fever with anhidrosis. It contains 0.5-2.5% by weight of total alkaloids, of which ephedrine accounts for 30 to 90%. Recently, large amounts of ma-huang were used as a source of ephedrine in many dietary supplements formulated for weight reduction, because ephedrine has been found effective in inducing weight loss in diet-restricted obese patients. However, indiscriminate consumption of ma-huang-containing products has resulted in many cases of poisoning, some of which were fatal. The objective of this study is to investigate the relative toxicity of ma-huang extracted under different conditions. The toxicities of various extracts were assayed using MTT colorimetry on a battery of cell lines, while ephedrine alkaloids were analyzed with HPLC. The results are summarized as follows. (1) The cytotoxicity of all ma-huang extracts could not be totally accounted for by their ephedrine contents, suggesting the presence of other toxins in the extracts. (2) Grinding was a significant condition enhancing the toxicity of the extracts. (3) The relatively high sensitivity of the Neuro-2a cell line to the toxicity of ma-huang extracts suggests that the toxic principles were acting on neuronal cells. (4) One condition to produce a ma-huang extract with high ephedrine-to-toxins ratio would be to boil the whole herb for two h.

Benzene-induced micronuclei formation in mouse fetal liver blood, peripheral blood, and maternal bone marrow cells.

The transplacental cytogenetic effects of benzene were studied by using the micronucleus test of polychromatic erythrocytes (PCE) found in both fetal liver and fetal peripheral blood, and were compared with PCE from maternal bone marrow. Timed-pregnant mice received single intraperitoneal doses of benzene (0, 109, 219, 437, or 874 mg/kg bw) on the 14th day of gestation and were sacrificed 21 hr after injection. Benzene elicited a significant increase (P less than 0.01) in the frequency of micronucleated polychromatic erythrocytes (MNPCE) in fetal liver blood cells (0.55 to 1.36%, control 0.18%) at doses of 219 to 874 mg/kg, and in fetal peripheral blood cells (0.49 to 0.58%, control 0.25%) and maternal bone marrow cells (0.53 to 0.70%, control 0.10%) at doses of 437 and 874 mg/kg. The data demonstrate that benzene is a moderate transplacental clastogenic agent, and that the mouse transplacental micronucleus test using fetal liver blood cells is a potentially more sensitive indicator of the genotoxicity of benzene than either fetal peripheral blood or maternal bone marrow cells.

Dynamics of C2 toxin and chlorophyll-a formation in the dinoflagellate Alexandrium tamarense during large scale cultivation.

The production of paralytic shellfish toxins (PSTs) by the dinoflagellate Alexandrium tamarense ATCI01, a toxigenic strain isolated from South China coastal waters, was studied in batch cultures in relatively large volumes (20l). Under nutrient-replete conditions, this strain produced C2 toxin (C2T) as a predominant PST. In a 15-day production culture, phosphate was depleted by day 4, the stationary phase began at day 6, and the toxin productivity peaked at day 10, in which the cell content of C2T reached 76 fmol per cell. Much of the toxin was produced after the depletion of phosphate in the medium suggesting that C2T is a secondary metabolite. Aeration with small bubbles was useful in increasing cell mass and toxin yield. Chlorophyll-a (Chl-a) was formed in algal cells until the culture entered the stationary phase, after which Chl-a began to disappear rapidly from the culture while the C2T content continued to rise. These results suggest a metabolic relationship between Chl-a and C2T.

Metabolism, DNA binding, and cytotoxicity of aflatoxin B1 in tracheal explants from Syrian hamster.

Metabolism, DNA binding and cytopathological effects of aflatoxin B1 (AFB1) were studied in isolated tracheal explants from Syrian golden hamsters. Explants were exposed to 0.1, 0.5 and 1.0 microM [14C]AFB1 in Dulbeccos's modified Eagle medium for 24 h, then analyzed for AFB1-DNA binding and AFB1 metabolism. Binding (pmol AFB1/mg DNA) was dose-related (16.3 +/- 1.9 to 180.8 +/- 16.1) and analysis of the culture medium revealed the metabolic conversion products aflatoxicol (AFL) and aflatoxin Q1 (AFQ1). Ultrastructural analysis of sections of tracheal epithelium revealed degenerative changes primarily in the non-ciliated epithelial cells. Autoradiographic analysis of the same treated explants, however, showed no discernible distribution of label with respect to either cell type or cell location, with the exception of increased grain densities overlying vacuoles containing dark droplets. In addition, S9 prepared from hamster trachea was shown to activate AFB1 to mutagens detectable by Salmonella typhimurium TA 98, but was approximately 70 times less active on a per mg protein basis than was S9 prepared from hamster liver. These results demonstrate the metabolic capabilities of tracheal epithelial cells in the activation of AFB1, thus indicating that AFB1 present in respiratory particles may be activated by pulmonary mixed-function oxidases, posing a hazard to those exposed.

Mutagenicity of fungal metabolites related to aflatoxin biosynthesis.

Fungal metabolites identified as the intermediates in aflatoxin biosynthetic pathway were screened for their mutagenic activity to Salmonella typhimurium TA98. Norsolorinic acid, averufin, and versiconal acetate were found to possess questionable mutagenic activity, but versicolorin A, and sterigmatocystin were significant mutagens relative to aflatoxin B1. The mutagenic activity appears to be related to the bisfuran and not the anthraquinone moiety of the molecule, even though the latter is a key structure of such potent carcinogenic mycotoxin as luteoskyrin.

The kinetics of mutagen excretion in the urine of cigarette smokers.

The excretion of mutagens in the urine of cigarette smokers was studied as a model for absorption and elimination of complex carcinogenic and mutagenic mixtures in humans. Urine was collected from an occasional smoker who smoked 1 cigarette (17 mg tar/cigarette) and from a heavy smoker (smokes approximately 20 cigarettes/day) who quit for 2 days and then resumed smoking. Urine samples were collected for 6 days, including a 2-day pre-smoking period for the occasional smoker and pre-abstention period for the heavy smoker, respectively. Mutagen excretion patterns were determined by extracting the mutagens in each urine sample with XAD-2 resin and testing the extract in a microsuspension modification of the Salmonella/microsome liquid-incubation assay using bacterial strain TA98 with metabolic activation. Peak mutagenic activity of the urine collected from the two smokers appeared 4-5 h after the beginning of smoking. Activity decreased to pre-smoking "baseline' levels in approximately 12 h for the occasional smoker, and the activity for the heavy smoker approached the occasional smoker's 'baseline' in approximately 18 h after the cessation of smoking. The mutagen excretion patterns of the occasional smoker after smoking a single cigarette suggests that, the mutagens, as detected by the Salmonella assay, are absorbed rapidly (3-5 h) and are eliminated from the body following first order kinetics. The excretion rate constant for the occasional smoker was approximately 0.1 h-1 and the half-life (T1/2) was approximately 7 h.

Antimutagenicity of ellagic acid against aflatoxin B1 in the Salmonella microsuspension assay.

Ellagic acid (EA) is a phenolic compound with antimutagenic and anticarcinogenic properties. It occurs naturally in some foods such as strawberries, raspberries, grapes, black currants and walnuts. In the present study, we used the Salmonella microsuspension assay to examine the antimutagenicity of EA against the potent mutagen aflatoxin B1 (AFB1) using tester strains TA98 and TA100. Further, we used a two-stage incubation procedure that incorporates washing the bacterial cells free of the incubation mixture after the first incubation to investigate EA and AFB1 interaction. Three different concentrations of AFB1 (2.5, 5 and 10 ng/tube) were tested against five different concentrations of EA for TA98 and TA100. EA significantly inhibited mutagenicity of all doses of AFB1 in both tester strains with the addition of S9. EA alone was not mutagenic at the concentrations tested. The greatest inhibitory effect of EA on AFB1 mutagenicity occurred when EA and AFB1 were incubated together. Lower inhibition was apparent when the cells were first incubated with EA followed by a second incubation with AFB1, and also when the cells were first incubated with AFB1 followed by a second incubation with EA alone. The results of the sequential incubation studies support the hypothesis that one mechanism of inhibition could involve the formation of a chemical complex between EA and AFB1.

Micronucleus formation in cultured fetal liver blood cells using mitomycin C.

Mouse fetal-liver blood cells were cultured and used to investigate micronucleus formation after exposure to mitomycin C (MMC). The isolated fetal cells were incubated in a medium supplemented with erythropoietin (EPO), and the frequency of micronuclei formation was detected in polychromatic erythrocytes (PCE). The effects of four variables were investigated: (1) MMC exposure dose, (2) MMC exposure time, (3) incubation time, and (4) EPO concentration. PCE were formed by proliferation and differentiation of the erythroid cells in culture. Micronucleated PCE (MNPCE) were observed in a dose-dependent manner after exposing the cultured cells with up to 1.0 microgram/ml MMC. The optimum time of MMC exposure and post-exposure incubation was 3 h and 48 h, respectively, and the optimum EPO concentration was 0.25 U/ml. Mouse fetal-liver PCE are sensitive primordial cell targets that can be obtained in relatively large numbers from a single pregnant animal. The procedure is relatively simple and potentially useful in detecting mutagens and carcinogens capable of causing chromosomal damage.

Measuring personal exposure to airborne mutagens and nicotine in environmental tobacco smoke.

The exposure of individuals to environmental tobacco smoke (ETS) is of increasing public health concern because epidemiological studies have associated passive smoking with increased risk of a variety of adverse health effects among non-smokers including lung cancer. As a way to measure individual exposure to the mutagenic compounds in the complex mixture of ETS, we used a sensitive Salmonella/microsome micro pre-incubation (microsuspension) assay to detect mutagenicity of particulate matter collected on filters from low volume (1.7 1/min flow rate) personal sampling pumps. Airborne nicotine was collected concurrently as a marker for ETS exposure. In pilot-field studies, individual exposure to ETS was measured in two separate indoor environments in which smokers were present: a gambling casino and a bingo parlor. Total suspended particulate matter (TSP) was collected on filters worn near the breathing zone of non-smoking individuals. Sampling times ranged from 40 min to 6 h. All extracts of filters had detectable levels of mutagenic activity (TA98, +S9) resulting in airborne mutagenic activity concentrations of 500-5000 rev/m3. The mutagenic activity of the filters from the casino and bingo parlors was significantly correlated with total particulate matter per filters (n = 12; Rho = 0.85, p less than 0.01) and with airborne nicotine per filter (n = 12; Rho = 0.95, p less than 0.01). The microsuspension assay was sufficiently sensitive to detect the mutagens associated with extracts of particulate matter from low volume samples (0.2-0.6 m3) in these indoor environments over a relatively short sampling time, and could be useful in studies of personal exposure to the mutagens in environmental tobacco smoke. Further, airborne nicotine concentrations were highly correlated with airborne mutagenicity and the mutagenic activity associated with ETS could therefore be estimated by the concentrations of nicotine.

Quantitative integration of the Salmonella microsuspension assay with supercritical fluid extraction of model airborne vapor-phase mutagens.

Vapor-phase mutagens are potentially a major class of toxic contaminants in ambient and indoor air. These compounds are not routinely analyzed due to a lack of an established integrated methodology to quantitatively trap, extract and test the compounds in a bioassay. In a previous report, we emphasized the trapping of volatile and semi-volatile mutagens and the extraction of these compounds using supercritical carbon dioxide (CO2). In the present study, we discuss the use of a bioassay for the quantitation of the model mutagens, ethylene dibromide(EDB) and 4-nitrobiphenyl (4-NB), trapped from an airstream. The compounds EDB and 4-NB were released into a controlled airstream, trapped on XAD-4 adsorbent, and were extracted using supercritical CO2. The extract was tested in a microsuspension modification of the Ames Salmonella/microsome test adapted for volatile compounds. Linear dose-response relationships were obtained for supercritical CO2-extracted EDB using tester strain TA100 (+/- S9) and for 4-NB using tester strains TA98 and TA100 (-S9). Standard dose-response curves with known amounts of the compounds were also determined for comparison with measured amounts of the model compounds collected in an airstream. The gas chromatographic (GC)- and bioassay-determined quantities of EDB and 4-NB were highly correlated, accurate and precise. For example, bioassay-determined EDB concentrations were within 10% of the GC-determined concentrations. Our results demonstrate that the integrated methodology for vapor-phase mutagens developed in this study would be useful for quantitative analysis of these and related airborne vapor-phase mutagenic compounds.

The effects of butylated hydroxytoluene on the in vitro metabolism, DNA-binding and mutagenicity of aflatoxin B1 in the rat.

Butylated hydroxytoluene pretreatment in the rat enhanced the total in vitro metabolism of aflatoxin B1 by the hepatic postmitochondrial fraction (S-9) and increased the formation of aflatoxin M1, aflatoxin Q1 and a metabolite tentatively identified as the aflatoxin-glutathione conjugate, the latter being the major metabolite produced. Addition of diethyl maleate, a glutathione depletor, to the incubation mix, reduced formation of the conjugate. No significant difference between treated and control animals was observed in the S-9-mediated binding of aflatoxin B1 to calf thymus DNA. However, the mutagenicity of aflatoxin B1 in Salmonella typhimurium TA98 was significantly lower in the presence of S-9 from BHT-treated rats than with S-9 from controls.