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Biomedical subjects

S S Hee

Publications and source records attributed to S S Hee.

17 recordsLinked to original sources
PubMed2001

Bacterial mutagenicity of some tobacco aromatic nitrogen bases and their mixtures.

The first aim was to compare the genotoxicities of two tobacco-specific nitrosamines (TSNA), 4-(methylnitrosamino)-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) in two types of tests, the Salmonella reverse mutation assay (250-2000 microg per plate) and the Mutatox test (up to 1000 microg/ml) using dark mutant M-169 of Vibrio fischeri. The second aim was to assess the effects of single other tobacco chemicals and metabolites (nicotine (NIC), cotinine (COT), trans-3-hydroxycotinine (3HC), cotinine-N-oxide (CNO) and nicotine-N-oxide (NNO)) on the mutagenic responses at relative concentrations observed physiologically. The Salmonella strains were TA100, TA7004, TA7005, and TA7006, all showing missense backmutations that are characteristic of the TSNA. NNN was a direct mutagen to strains TA100, TA7004, and in the Mutatox test, and was not mutagenic in the presence of rat or hamster S9. NNK was mutagenic only in strain TA7004 with rat and hamster S9, but not in TA100, but was directly mutagenic in the Mutatox test. While all the other tobacco chemicals were not mutagenic alone to strains TA100 and TA7004 in the presence and absence of rat or hamster S9, the Mutatox test produced direct mutagenicity for COT, 3HC, and NNO, but not CNO. The latter was mutagenic in the Mutatox test with rat or hamster S9, but only rat S9 was effective for COT, NNO and 3HC. Inhibitory potentiations of NNN by NIC and COT were observed on strain TA7004, and by NIC on strain TA100. There were no interactions on NNK in the presence of S9 for strain TA7004 or TA100. In contrast, a complex inhibition and enhancement behavior occurred in the Mutatox test for each interaction, but no effects were observed for CNO on NNK without S9, and few for NIC on NNK with hamster S9. Compounds which showed no activity alone modulated the genotoxicity of two potent TSNAs in both types of tests.

Animals↗
PubMed2001

Trace metals in fish and invertebrates of three California coastal Wetlands.

Metal concentrations were measured in selected fish and invertebrate species from Mugu Lagoon, Malibu Lagoon and Ballona Wetlands in southern California in order to assess the extent of metal contamination in these three wetlands. Ranges of element concentrations (in microgram/g) found in biota were: Zn 12-650; Cu 1.9-440; Ni < 1-37; Cr < 1-55; Pb < 0.5-6.8; As < 1-8.5; Se < 1-3.8; Cd < 0.2-0.90; and Ag < 0.3-5.9. Relative to previous studies of California biota, the highest metal concentrations found were for chromium and nickel. The highest levels were in one of the two bottom-dwelling fish (juvenile Leptocottus armatus) (55 micrograms/g) and the two water-column fish sampled (Fundulus parvipinnis and Atherinops affinis) (30 and 24 micrograms/g). At Ballona Lagoon, elevated levels of copper and silver were found in the bivalve Tagelus californianus (440 and 5.9 micrograms/g). Chromium and nickel appeared to be most persistent in fish from Mugu (4.6-55 and 2.6-37 micrograms/g), the most northern site and an active military base, and Ballona (< 1-30 and < 1-16 micrograms/g), believed to be the most metal-contaminated site. Compared to previously measured metal concentrations in species of California coastal waters, these regions revealed higher levels of chromium, nickel, silver, arsenic, zinc, copper and, to a lesser extent, cadmium and selenium. Chromium and silver were present at high enough levels at all three sites to be considered environmental health hazards.

Animals↗
PubMed2000

Optimization of a solid sorbent dynamic personal air sampling method for aldehydes.

A solid sorbent personal dynamic air sampling method for aldehydes using chemisorption with 20 percent (w/w) O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) on Tenax TA has been optimized for several aldehydes. The method for formaldehyde was developed after optimization for valeraldehyde and acrolein. The effects of temperature, intermittent exposure, and flow rate on sampling efficiency were investigated. Vapors of known concentrations were generated in Tedlar gas bags by syringe injection. Aldehyde chemisorption by reaction with 200-mg coated solid sorbent in a Pyrex Tube (7-cm length, 7-mm OD, and 5-mm ID) occurred during dynamic collection with a personal sampling pump operated at 10, 50, or 100 mL/min. The oxime derivatives were 81-87 percent desorbed by shaking with hexane for two minutes or more, resulting in coefficients of variation ranging between 4-7 percent. Aliquots were then injected for gas chromatographic analysis on a nonpolar capillary column with mass spectrometric or 63Ni electron capture detection. Formaldehyde at 8 ppm-hours equivalent to the permissible exposure limit (PEL) concentration was sampled with a recovery of 94 +/- 4 percent at 50.0 +/- 0.5 mL/min. Valeraldehyde and acrolein at their PELs showed no significant differences (P < 0.05) in recoveries at different relative humidities (1 and 90%), temperatures (1, 25, and 40 degrees C), or intermittent sampling protocol. The sampler capacity at 75 percent recovery was at a PFBHA:aldehyde molar ratio of 12:1 at 10.0 +/- 0.1 mL/min, 17:1 at 50.0 +/- 0.5 mL/min, and 26:1 at 100 +/- 1 mL/min.

Adsorption↗
PubMed2000

Regulated workplace ketones and their interference in the PFBHA method for aldehydes.

Ketones are the major positive interferences for an aldehyde dynamic air sampler that consists of 200-mg 20 percent (w/w) O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) on Tenax TA contained in a Pyrex tube 7-mm OD, 5-mm ID, and 70-mm in length, that utilizes a personal battery-powered pump at 10-50 mL/min. The ketone O-oxime derivatives were synthesized to allow absolute quantitation of O-oximes formed during sampling. Wet spiking allowed ketone recoveries to be found. Ketone vapors of known concentrations were generated statically in Tedlar gas bags. The O-oximes were desorbed with hexane, and an aliquot injected for gas chromatographic analysis on a nonpolar capillary column with mass spectrometric or electron capture detection. Gas phase recoveries up to 200 ppm-hour loadings exceeded 75 percent at 25 degrees C for chloroacetone, cyclohexanone, diacetone alcohol, diethyl ketone, dipropyl ketone, ethyl butyl ketone, methyl amyl ketone, methyl butyl ketone, 2-methylcyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, and methyl propyl ketone. The recoveries for acetophenone, 2-chloroacetophenone, and ethyl amyl ketone were lower than 75 percent, and were caused by steric hindrance. Sampling for both aldehydes and ketones is recommended at 10 mL/min for TLV concentrations.

Air Pollution, Indoor↗
PubMed1999

Glove permeation tests using novel microchemical techniques for 2, 4-dichlorophenoxyacetic acid (2,4-D) derivatives.

The aim was to assess the permeation of different herbicide emulsion concentrate formulations of 2,4-dichlorophenoxyacetic acid (2,4-D) as 60.8 and 83.5% butoxyethyl ester (BEE) and 46.8% dimethyl amine salt (DMAS) through four types of glove materials (lined unsupported nitrile, unlined unsupported butyl, Silver Shield laminate, and Viton). This entailed the development of new microchemical techniques to allow sensitive capillary gas chromatography/mass spectrometry (GC/MS) of the permeated herbicide. The 2,4-D DMAS was esterified to the methyl ester by boron trifluoride-methanol complex with 99.2 +/- 3.7% efficiency using microwave heating to minimize reaction time and to process microsamples. The GC/MS detection limit was 5 ng/ml (ppb) of 2,4-D DMAS in the collection medium. The permeates from the ester formulations were analyzed directly for the ester above the detection limit of 9 ng/ml (ppb) BEE. The permeation investigations utilized the American Society for Testing Materials (ASTM)-type permeation cells with liquid collection media. The results showed that these gloves could provide at least 6 h protection for these formulations.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1999

A new passive sampler for regulated workplace aldehydes.

A new solid sorbent passive air sampler for aldehydes had a silicone membrane atop a cylindrical diffusion path of 1.1 cm length and 1.3 cm diameter above a 10 percent (w/w) O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) Tenax TA pellet. Known vapor concentrations of Occupational Safety and Health Administration (OSHA)-regulated aldehydes near their permissible exposure limits were generated from a syringe pump dynamic air dilution system that was connected to an exposure chamber. The O-oxime derivatives from aldehyde reaction with PFBHA were desorbed with hexane, and quantified by capillary gas chromatography/mass spectrometry (GC/MS) or gas chromatography/electron capture detection (GC/ECD). The capacity for aldehydes with one carbonyl group was 30-35 mumoles, and 15 mumoles for the dialdehyde, glutaraldehyde. The experimental sampling rates in mL/min were 8.86 +/- 0.38, acetaldehyde; 11.69 +/- 0.32, chloroacetaldehyde; 7.85 +/- 0.19, crotonaldehyde; 9.97 +/- 0.10, formaldehyde; 6.47 +/- 0.42, furfural; and 4.46 +/- 0.15, glutaraldehyde. Other data on valeraldehyde and acrolein have shown that the sampling constants were independent of face velocity between 0.1 to 0.35 m/s (20 to 70 fpm), temperatures between 9 to 48 degrees C, RH between 3 to 79 percent, and intermittent sampling exposure pattern.

Air Pollutants↗
PubMed1998

Simultaneous gas chromatographic-mass spectrometric quantitation of the alkylbenzene inert components, pesticide manufacturing by-products and active ingredient in two malathion formulations.

A rapid, reliable and effective method for direct determination of the inert components, manufacturing by-products of the pesticide, and active ingredient in two malathion formulations has been established using capillary gas chromatography-mass spectrometry (GC-MS) with the internal standard method. The C2-, C3-, and C4-alkylbenzenes, the major pesticide manufacturing by-products (O,O,S-trimethylthionophosphate, diethyl maleate and O,O,O-trimethylthionophosphate), and malathion were resolved, and quantified in the same chromatogram. Structural identification was based on MS total ion current data, comparison of GC retention times with those of authentic standards, and retention indices. O,O,S-Trimethylthionophosphate was quantified at 3.57 +/- 0.31% (w/w) in one malathion formulation. While the malathion contents were within specifications for both formulations, the total alkylbenzene contents were not.

Algorithms↗
PubMed1998

Biological monitoring of workers exposed to carbon disulfide.

Urinary 2-thiothiazolidine-4-carboxylic acid (TTCA) concentrations and corresponding personal breathing zone carbon disulfide (CS2) air concentrations were measured for worker populations at a Tennessee rubber product facility and a Virginia viscose rayon plant. At the rubber product facility, all of the 19 workers had urinary TTCA levels less than the limit of detection (LOD) of about 0.03 mg/L, equivalent to less than 0.5 ppm of CS2 in air. At the viscose rayon plant, five of six workers, although wearing half-mask cartridge respirators, showed increased urinary TTCA during the workshift. The cutters and spinners had the largest increases in urinary TTCA concentrations; they also had the highest breathing zone exposures to CS2. The TTCA concentrations for three cutters and spinners did not return to normal preshift levels of < 0.3 mg/g creatinine before the start of the next shift. The arithmetic mean respirator workplace protection factor (WPF) was 7.0 +/- 2.2. Increase in urinary TTCA concentration during the workshift and postshift urinary TTCA concentration reflected CS2 air concentration equally well. In conjunction with air monitoring results, urinary TTCA concentrations allow determination of the WPF afforded workers wearing respirators and identify workers not adhering to safety rules and good work practices. Workers at risk of adverse health effects from overexposure to CS2 for any reason may thus be identified.

Air Pollutants, Occupational↗
PubMed1995

Determination of hemoglobin adduct levels of the carcinogen 2,4-diaminotoluene using gas chromatography-electron impact positive-ion mass spectrometry.

A procedure to determine hemoglobin adduct yields resulting from exposure to the carcinogen 2,4-diaminotoluene (2,4-TDA) was developed using gas chromatography-electron impact positive-ion mass spectrometry. Liberated 2,4-TDA was quantified following alkaline hydrolysis of hemoglobin. Optimized derivatization of free 2,4-TDA with hepatafluorobutyric anhydride allowed detection of hemoglobin adduct levels as low as 5 ng/g Hb. Pure HFBA-2,4-TDA showed a linear dynamic range of 50 to 5000 pg. The quantitative extraction and recovery of liberated 2,4-TDA (ca. 100%) following hemoglobin hydrolysis allows accurate and precise determinations of adduct yields.

Animals↗
PubMed1995

Ketone EC50 values in the Microtox test.

The Microtox EC50 values for the following ketones are reported in the following homologous series: straight chain methyl ketones (acetone, 2-butanone, 2-pentanone, 2-hepatonone, 2-octanone, 2-decanone, and 2-tridecanone); methyl ketones substituted at one alpha carbon (3-methyl-2-butanone; 3,3-dimethyl-2-butanone); methyl substituted at two alpha carbons (2,4-dimethyl-3-pentanone; 2,2,4,4-tetramethyl-3-pentanone); phenyl groups replacing methyl in acetone (acetophenone; benzophenone); methyl groups substituted at the alpha carbons of cyclohexanone; and 2,3- 2,4-, and 2,5-hexanediones, most for the first time. While there were linear relationships between log EC50 and MW for the straight chain methyl ketones, and for methyl substitution at the alpha carbon for methyl ketones, there were no other linear relationships. As molecular weight increased, the EC50 values of soluble ketones decreased; as distance between two carbonyl groups decreased so too did EC50 values. Thus, for the ketones the geometry around the carbonyl group is an important determinant of toxicity as well as MW, water solubility, and octanol/water coefficient.

Ketones↗
PubMed1995

Genotoxicity of nicotine and cotinine in the bacterial luminescence test.

Cotinine was positive in the absence of S9 in the bacterial luminescence genotoxicity test at 1.25 mg/ml (9-15 h incubation) and at 2.50 mg/ml (18-30 incubation hours) signifying potential mutagenicity and teratogenicity. In the presence of S9, cotinine was positive at 1.25 mg/ml after 9 incubation hours. In contrast, nicotine was not at any concentration or incubation time. Nicotine/cotinine mixtures were still positive at physiological concentrations, with potentiation relative to cotinine alone with and without S9. Standard additions of nicotine to other positive controls such as 2-aminoanthracene (2AA) (a mutagen causing point mutations on activation), phenol (a DNA intercalator), and N-methyl-N'-nitrosoguanidine (MNNG) (a direct-acting point mutagen) revealed a complex nicotine effect. Nicotine antagonized MNNG without S9, and potentiated MNNG with S9, 2AA with and without S9, and phenol without S9. Cotinine was not a very potent agent relative to the positive controls. Since cotinine has been considered an inactive biological monitoring marker of nicotine absorption in humans, the present results indicate that the many health effect correlations based on cotinine in urine, serum, saliva, and blood may involve more cause and effect than thought hitherto.

Biotransformation↗
PubMed1990

Mutagenesis assays on urines produced by patients administered adriamycin and cyclophosphamide.

The XAD-2 resin concentration/elution system for concentration of mutagens contained in urines was optimized for cancer patients who had been administered such antineoplastic agents as adriamycin (ADR; doxorubicin), cyclophosphamide (CP), methotrexate, vincristine, and 5-fluorouracil. In the reverse mutation assay, Salmonella typhimurium strains TA1535 and TA98 differentiated between CP (with S9 fraction) and ADR (without S9), respectively. No dose-response for CP was observed. There was a dose-response to ADR by TM677 in the presence of S9 using a forward mutation assay. However, while the reverse mutation assays successfully detected ADR and CP administration in the presence of each other in terms of urine mutagenicity, the forward mutation assay did not, since unidentified CP metabolites were also detected in the latter. None of these systems detected mutagenic urines from tobacco smokers, although reaction of these urines with beta-glucuronidase allowed this type of source to be detected also.

Animals↗
PubMed1988

Elemental alterations during the exposure of 1,2-dichloroethane (EDC), disulfiram (DSF), and EDC-DSF to male Sprague-Dawley rats.

Trace elements participate in the organ specific impact of 1,2-dichloroethane (EDC) and Disulfiram (tetraethylthiuram disulfide; Antabuse (DSF] administered singly or together, on male Sprague-Dawley rats exposed by diet (AIN-76) to DSF (0 and 0.15% for 10 d before and during exposure to EDC) and by inhalation to EDC (0, 153, 304, 455 ppm (v/v); 7 h/d for 5 d/wk for 30 exposure days). Kidney, liver, spleen, and testes at exposure d 30 as well as progressive urine samples were examined for elemental content by simultaneous inductively coupled plasma atomic emission spectroscopy. Each compound singly or together produced EDC dose related (r greater than or equal to 0.8) changes in metal content in organs relative to controls. There were increases induced by EDC alone for P and Sr in the liver and decreases for Fe, Mg, and P in the spleen. EDC in DSF-exposed animals caused increases in Ca, Cu, Fe, Mn, and S and a decrease in K in the liver; increases in Ca, Cu, Fe, Mn, Mo, P, and S and a decrease of Zn in the testes; an increase in Fe and a decrease in K in the spleen; and an increase of P in the kidney. DSF alone increased Cu in the liver but decreased it in the testes and kidney; Pb was increased in the liver and kidney and Zn in the liver, spleen, and kidney; Al and Si were increased also in the liver, S in the spleen, and K in the kidney; Mn and Na were decreased in the kidney. The organs showing histopathology (the liver and testes) both showed increases in Ca, Cu, Fe, Mn, and S. Metals in urine characterized a "shock" impact of the initial exposure by initial excretion of Na and retention of most other elements. After steady state (greater than 12 d), EDC alone caused increases for Sr and Zn; for EDC-DSF, EDC also decreased Na in addition to the changes elicited by DSF alone (increases in S and Zn and a decrease for Cu). The results were interpreted from the perspective of the effects of metals on the glutathione detoxicative pathway, the concentration of free diethyldithiocarbamate in urine, and an interaction with bone. Mechanisms of action of EDC, DSF, and EDC-DSF must include consideration of trace elements in addition to organic intermediates, metabolites, and enzymes.

Animals↗
PubMed1986

Interaction between 1,2-dichloroethane and tetraethylthiuram disulfide (disulfiram). II. Hepatotoxic manifestations with possible mechanism of action.

The synergistic hepatotoxicity of dietary disulfiram (DSF) with 1,2-dichloroethane (DCE) subchronically administered by inhalation at three concentration levels (150, 300, and 450 ppm) was studied. The criteria for hepatotoxicity were treatment-related increases in serum activities of sorbitol dehydrogenase, 5'-nucleotidase, and alkaline phosphatase, and in liver-to-body weight ratios. DSF alone did not elicit these responses while DCE at the highest concentration level increased liver-to-body weight ratios and the activity of 5'-nucleotidase. Exposure to DSF alone decreased cytochrome P450 levels, but in combination with DCE, the decrement of cytochrome P450 was additive in a DCE concentration-dependent manner. However, depression of cytochrome P450 by DCE alone was not concentration dependent. Although DSF and DSF/DCE combination increased the activity of glutathione S-transferases (GSTs), both DSF and DCE singly and in combination increased the tissue levels of reduced glutathione (GSH). Evidence is presented showing that the potentiation of the hepatotoxicity of DCE observed in the presence of DSF may be due to an inhibition of microsomal mixed-function oxidase-mediated metabolism of DCE and to a compensatory increase in DCE metabolism to reactive metabolites generated by GST-mediated conjugation of DCE with GSH.

Animals↗
PubMedDate not supplied

Separation of pH, dilution, ionic strength and chemical matrix effects for biological monitoring of urines with the Microtox test using nicotine, cotinine and reference urines.

The aim was to investigate the factors influencing light emission from Photobacterium phosphoreum in the Microtox test to interpret bioassay results for urine. Four reference urines were assessed as reference materials for the bioassay. Nicotine and cotinine were investigated as urinary markers for tobacco exposure. The optimum luminescence conditions were: 1.85%-3.25% NaCl, 0.33-0.58 mol/L ionic strength, and pH 5.8-6.7. Low pH values and high concentration of toxic trace metals were important factors in this study. Unexpected toxicity for a Standard Reference Material was attributed to zinc contamination. Nicotine and cotinine together exhibited antagonistic effects in 2% saline but this could not be observed in the urines because of substantial urine toxicity. Thus practical urinary biological monitoring with the Microtox test necessitates excretion of metabolites and compounds that are much more toxic than the urine components. Also, separation of the effects of physical factors like pH, ionic strength and dilution is essential before chemical toxicity effects can be assigned. This is the first report of Microtox EC50 values for nicotine and cotinine. The results have application to environmental samples since analyses are often uncontrolled relative to pH, ionic strength and dilution.

Biological Assay↗
PubMedDate not supplied

A new passive sampler for regulated workplace ketones.

A new solid sorbent passive air sampler for ketones has a silicone membrane atop a diffusion cylindrical path length of 1.1 cm and diameter 1.3 cm above a pellet of Tenax TA coated with 10% (w/w) O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride. Vapors of known concentrations approximating their workplace permissible exposure limits of Occupational Safety and Health Administration-regulated ketones at a relative humidity (RH) of 3 +/- 1% were generated by a syringe pump connected to a dynamic air dilution system connected to an exposure chamber that allowed measurement of face velocities, temperatures, exposing vapor concentrations, and RHs. The O-oxime derivative was desorbed with hexane, and an aliquot injected for gas chromatographic analysis on a nonpolar capillary column by mass spectrometric or electron capture detection. The experimental passive sampler sampling rates in milliliters per minute at 25 degrees C were 4.07 +/- 0.49, cyclohexanone; 6.30 +/- 0.59, diethyl ketone; 6.31 +/- 0.31, ethyl n-butyl ketone; 3.78 +/- 0.25, methyl n-amyl ketone; 3.43 +/- 0.19, methyl n-butyl ketone; 6.48 +/- 0.64, methyl ethyl ketone; 4.37 +/- 0.43, methyl isopropyl ketone; and 4.57 +/- 0.17, methyl n-propyl ketone. These preliminary data show that sterically unhindered ketones can be sampled by the passive sampler as well as aldehydes.

Chromatography, Gas↗