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Biomedical subjects

D J Lisk

Publications and source records attributed to D J Lisk.

At least 37 records · Page 2Linked to original sources
PubMed1994

Enrichment of selenium in allium vegetables for cancer prevention.

We previously reported that garlic cultivated with selenium fertilization is superior to regular garlic in mammary cancer prevention in the rat 7,12-dimethylbenz[a]anthracene (DMBA) model (Nutr. Cancer, 17, 279-286, 1992). A new crop of high-selenium garlic was harvested in 1992 and was used in a dose-response study to confirm the reproducibility of the product and the bioassay. Supplementation of 1 or 2 p.p.m. Se in the diet from the high-selenium garlic produced a 56% or 75% reduction respectively in the total tumor yield. Since both garlic and onion belong to the same allium family of vegetables, we were also interested in finding out whether our experience with garlic could be similarly applied to onion. A high-selenium onion crop was grown in the same season and location and with the same schedule of selenium fertilization. Two distinct differences were noted with the high-selenium onion regarding its capacity to accumulate selenium and its efficacy in cancer prevention. First, the selenium concentration in onion was considerably lower (28 p.p.m. Se dry wt) as compared to that found in garlic (110-150 p.p.m. Se). Second, given the same levels of selenium supplementation, the high-selenium onion was apparently not as powerful as the high-selenium garlic in mammary cancer inhibition. Thus different plants, even those of the same genus, may respond in their unique way to selenium fertilization and the biological benefits of selenium enrichment may vary depending on the species. Additional information from our study indicated that the high-selenium garlic/onion might provide an ideal system for delivering selenium-substituted analogs in a food form for cancer prevention: (i) they expressed a good range of anticancer activity and could be easily adapted for human consumption on a regular basis; (ii) their ingestion did not result in an excessive accumulation of tissue selenium, a concern that is associated with the standard selenium compounds such as selenite and selenomethionine; (iii) no perturbation in the maintenance of functional selenoenzymes were observed even at high levels of supplementation.

Allium↗
PubMed1993

Variability over time in the mutagenicity of ashes from municipal solid-waste incinerators.

Incineration of municipal solid waste as an alternative to its disposal in landfills has advantages such as volume reduction and generation of energy. However, both air emissions and the residual ash may pose environmental and human health hazards. The Ames mutagenicity assay was used to determine the mutagenicity of fly and bottom ash from two incinerators over time. This assay is an alternative to costly and time-consuming chemical analyses and is more realistic for the assessment of the best disposition of the ash i.e. whether it could pose a risk to handlers of the ash, whether it can be used in cement or as a fertilizer or whether it should be relegated to a landfill. The mutagenic potency of fly and bottom ash on a per g weight basis of material is similar. Furthermore, the variability over time in mutagenicity indicates that constant monitoring of incineration products and byproducts is essential.

Humans↗
PubMed1993

Bioavailability of selenium from selenium-enriched garlic.

We previously reported that garlic grown in a selenium-fertilized medium (selenium-enriched garlic) is superior to regular garlic in mammary cancer prevention in an animal model (Nutr Cancer 17, 279-286, 1992). The present study was designed to evaluate the nutritional bioavailability of selenium from this garlic with use of two liver selenoenzymes as biomarkers: glutathione peroxidase and type I 5'-deiodinase. Rats were fed a selenium-deficient diet (0.01 ppm Se) from weaning for four weeks to deplete both enzymes. They were then supplemented with nutritional levels of selenium (0.1-0.5 ppm) in the form of sodium selenite (positive control) or selenium-enriched garlic. Our results showed that selenium-enriched garlic was just as effective as selenite in restoring the activity of both selenoenzymes. This was demonstrated in a time course repletion experiment as well as in a dose-response experiment. Thus the selenium in selenium-enriched garlic has potent nutritional and anticancer efficacy. The type I 5'-deiodinase enzyme catalyzes the conversion of thyroxine (T4) to 3,5,3'-triiodothyronine (T3) and is responsible for most of the circulating T3. Because cancer chemoprevention by selenium usually requires pharmacological levels of selenium, we also examined the possible modulation of type I 5'-deiodinase by long-term feeding of selenium-enriched garlic at 3 ppm Se in the diet. The observation that a high intake of selenium-enriched garlic did not affect 5'-deiodinase activity suggests that its anticarcinogenic effect is unlikely to be mediated by an imbalance in the blood T4-to-T3 ratio.

Animals↗
PubMed1992

Residues of p,p'-DDE and mercury in lake trout as a function of age.

Lake trout (Salvelinus namaycush) of known age from 1 to 12 years were taken from Cayuga Lake in central New York State in 1991 and p,p'-DDE and mercury were determined in their flesh. The concentrations of p,p'-DDE and mercury increased significantly (p less than 0.001) with increasing age of the fish. The concentration of p,p'-DDE also increased significantly (p less than 0.001) with increasing fat content. The concentrations of p,p'-DDE were much lower than those found in Cayuga Lake trout of similar age captured in 1978.

Age Factors↗
PubMed1992

Mammary cancer prevention by regular garlic and selenium-enriched garlic.

The anticarcinogenic activities of regular (soil-grown) garlic and selenium-enriched garlic (cultivated in the greenhouse) were evaluated using the 7,12-dimethylbenz[a]anthracene-(DMBA) induced mammary tumor model in rats. In Experiment 1, milled regular garlic powder was added to the basal AIN-76A diet at 20 g/kg. The results from different schedules of supplementation suggested that a continuous treatment, which started before DMBA and persisted for the entire duration of the study, was most effective in tumor suppression. In Experiment 2, selected allyl group-containing sulfides that are normal constituents of garlic extract were given by gavage in three single doses immediately before DMBA. Several structurally related compounds were found to be protective during the initiation phase in the mammary cancer model. Although the present study was not designed specifically to elucidate the structure-activity relationship with respect to sulfur chain length or alkyl versus alkenyl substitution, our data showed that diallyl disulfide was more active than diallyl sulfide or allyl methyl sulfide. In Experiment 3, the anticarcinogenic activity of selenium-enriched garlic (containing 150 ppm Se dry weight from growth in a selenium-fertilized medium) was compared with that of regular garlic as well as selenite. Animals given the selenium-enriched garlic (final concentration 3 ppm Se in the diet) developed the fewest mammary tumors. Tissue selenium levels, however, were lower in these animals than in those fed the same amount of selenium from selenite. Our study demonstrated the feasibility of achieving cancer prevention with the use of a selenium-rich food system.(ABSTRACT TRUNCATED AT 250 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1992

Mutagens in urine sampled repetitively from municipal refuse incinerator workers and water treatment workers.

Municipal refuse incinerator workers may be exposed to mutagenic compounds from combustion gases and particulates during plant operation, maintenance, and ash removal procedures. The frequency of mutagens was measured by the Ames assay in 3 urine samples collected from each of 37 workers in 4 refuse incinerators and 35 (control) workers from 8 water treatment plants during June-August 1990. When comparing the first urine samples contributed by workers in each cohort, incinerator workers had a significantly (p < .05) increased risk of both direct-acting mutagens and promutagens (8/37 or 22% for each mutagen type) compared with water treatment workers (2/35 or 6% for each mutagen type). Smoking within 24 h before urine sampling was not a confounder of these results. Interestingly, there was no significant (p > .05) difference for risk of urinary mutagens or promutagens between the two cohorts when comparing, respectively, the second and third urine samples from each cohort. The repeatability of demonstrating urinary mutagens in individual incinerator workers was poor, suggesting that their exposure was highly variable and/or that these workers modified their exposure (e.g., wore masks) as a consequence of being studied. Factors that influence production of mutagenic compounds during refuse incineration and subsequent worker exposure are discussed.

Adult↗
PubMed1991

Urinary mutagens in cosmetologists and dental personnel.

Cosmetologists are occupationally exposed to a wide range of toxic chemicals both dermally and by inhalation. Since many of these chemicals are mutagens and may be excreted in urine, the Ames Salmonella typhimurium assay was used to determine the presence of direct-acting and promutagens in the urine of practicing cosmetologists in central New York State. A comparable group (age, gender, smokers) of dental hygienists and assistants in the same geographic area was used as the control cohort. The cosmetologists had a significantly higher (39 vs. 24%, p less than .03) frequency of direct-acting urinary mutagens but there was no difference between the groups in the frequency of promutagens. In the multivariate model, cosmetologists were at two times the risk of direct-acting mutagens compared to dental workers. Smoking regularly, within 24 h of taking the urine sample, and the number of cigarettes smoked daily were not associated significantly with direct-acting mutagens in urine. Similarly, having had a hair permanent or hair dyed within 7 d of urine sampling, years of employment, age, gender and use of protective gear were not predictive of direct-acting urinary mutagens. In contrast, employment was not associated with urinary promutagens but the risk was significantly increased with increasing age and cigarette smoking. Among possible adverse health symptoms queried, only the prevalence of skin rashes differed between the cosmetologists (29%) and dental personnel (15%) (p less than .05).

Adult↗
PubMed1991

Epidemiologic study of cadmium and lead in the hair of ceramists and dental personnel.

Ceramists may be exposed to heavy metal-containing dusts and vapors, especially when working with colored glazes. Because cadmium- and lead-containing glazes are commonly used, an epidemiologic study of the hair content of these metals among 70 ceramists in central New York was conducted. A comparably aged group of 75 dentists and orthodontists in the same geographic area was used as the control cohort. The median levels of both metals in the hair of the ceramists were significantly higher than those among the dental personnel. Most variables, including work habits and elements of the occupational setting, showed no significant effects on the concentrations of cadmium and lead in ceramists' hair. However, those ceramists whose studios were ventilated showed significantly lower levels of both metals in their hair. The use of protective masks or respirators was associated with significantly higher levels of cadmium in the hair of ceramists. A review of the literature on the subject is presented and the health significance of the results is discussed.

Adult↗
PubMed1991

Tissue deposition of polychlorinated biphenyls in cats fed Atlantic Ocean bluefish.

Bluefish (Pomatomus saltatrix), a very popular marine sport fish caught in Atlantic coastal waters, contain significant levels of polychlorinated biphenyls (PCBs). Since fish can be an appreciable portion of human and feline diets, a feeding study was conducted with cats fed exclusively bluefish for 86 days with determination of tissue concentrations of PCBs. The concentrations of PCBs in brain, liver, and fat were significantly higher (p = 0.01) in the fish-fed cats than in the control group using the Wilcoxon rank sum test. The highest PCB levels were in fat, the median concentrations being 48 and 0.61 ppm (dry weight) in the fish-fed and control cats, respectively. The significance of the results is discussed.

Adipose Tissue↗
PubMed1990

Cadmium deposition and hepatic microsomal activity in mice fed Swiss chard grown on municipal incinerator refuse ash.

Incineration of municipal solid waste results in the production of millions of tons of ash that may be typically high in heavy metals such as cadmium. Disposal of such ash in landfills capped with soil could lead to absorption of such metals by plants and deposition in foraging animal tissues. In this study, weanling, male mice were fed swiss chard that was grown on soil amended with 10% w/w municipal incinerator refuse ash. Cadmium was taken up by the swiss chard (8.15 ppm, dry wt). The mice fed diets containing 25% of ash-grown chard showed mean kidney and liver concentrations of cadmium (ppm, dry wt), respectively, of 2.80 +/- 0.30 and 0.45 +/- 0.03. Control mice fed soil-grown chard showed significantly lower kidney and liver concentrations of cadmium, i.e. 0.39 +/- 0.02 and 0.05 +/- 0.00 ppm. Since refuse incinerator ashes may contain various organic toxicants that can be hepatic microsomal inducers, the relative liver weights and hepatic microsomal aminopyrine N-demethylase and p-nitroanisole O-demethylase activities of mice fed control or ash-grown chard were measured. No consistent increases in these latter parameters were found in the ash-grown chard fed mice as compared with the control animals.

Animals↗
PubMed1990

Absence of cadmium in the blood of horses fed oats grown on municipal sludge-amended soil.

Effluents from a number of industries which are typically treated in municipal sewage plants result in cadmium-containing sludge. Disposal of such sewage sludge by application to agricultural land can result in uptake of cadmium by crops. In this study, oats were grown on soils which had been amended with sewage sludge from Syracuse, New York. The cadmium concentration in the sludge-grown oats was 1.79 ppm dry weight. Horses were fed the sludge-grown oats for 6 weeks during which time blood samples were taken for the determination of cadmium. No significant differences (p greater than 0.05) were found in the concentration of cadmium in the blood of the horses consuming the oats compared with that in the blood before feeding began (control). The well-known efficient accumulation of renal cadmium by horses may account for a lack of significantly increased cadmium in blood during the feeding period.

Animal Feed↗
PubMed1990

Urinary mutagens in municipal refuse incinerator workers and water treatment workers.

Municipal refuse incineration workers may be exposed to mutagenic compounds from gaseous and particulate emissions and during ash removal operations. The frequency of urinary mutagens was measured by the Ames test among a sample of 104 refuse incinerator workers in seven incinerator plants during March-May 1988. The frequency was compared to that observed in 61 water treatment employees in 11 municipal water treatment facilities during the same period. Incinerator workers had a significantly higher risk for urinary mutagens and promutagens as compared to water plant workers after controlling for age. Among incinerator workers, increased risk of having urinary mutagens was associated with workers who wore protective clothing (defined as clothing other than masks or gloves) or whose job classification was equipment repair. It also showed a weak positive association with increasing age. There was an increased risk of urinary promutagens associated with not wearing gloves. The presence or absence of mutagenicity in workers' urine varied with plant location. Incinerator operating conditions affecting the production of toxicants and mutagens are discussed and the results of other studies involving toxicant exposure of humans near incinerators are cited.

Adult↗
PubMed1990

Toxicity and tissue residue depletion of levamisole hydrochloride in young goats.

Toxicity and tissue residue depletion studies were conducted in young goats, using an oral drench formulation of levamisole hydrochloride. In the target animal toxicity study, 3 groups of 5 goats each were given levamisole orally to provide approximately 11.88, 23.76, or 35.64 mg of levamisole HCl/kg/d for 3 consecutive days; a fourth group of 5 goats served as untreated controls. Blood samples were taken for analysis of levamisole 1 day prior to dosing and 1, 2, 3, 4, and 7 days following the third dose. At the 35.64-mg/kg dose, 2 of 5 goats responded with typical cholinergic signs of toxicosis on each of the 3 days of dosing. The times for the onset of clinical signs of toxicosis ranged from 18 to 63 minutes, with an average duration of 32 minutes. Administration of 23.76 mg of levamisole HCl/kg resulted in hyperactive behavior in 1 of 5 goats only on the first day of dosing; no abnormal behavior was observed in any of the 5 goats following the second or third dose of levamisole HCl at 23.76 mg/kg. Untoward effects were not seen in the 5 goats dosed at 11.88 mg of levamisole HCl/kg or in the controls during the 3-day dosing period or in the following 7-day observation period. Overall, the observed signs of toxicosis did not become more severe, affect more goats, or persist for a longer period on subsequent dosing days.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗