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Biomedical subjects

J L Laseter

Publications and source records attributed to J L Laseter.

At least 19 recordsLinked to original sources
PubMed1999

Environmental contaminants and body fat distribution.

The effect of body mass index (BMI) and waist:hip ratio (WHR) on plasma levels of organochlorines [i.e., 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE)] was investigated in a sample of black and white women drawn from a population-based study in North Carolina. Organochlorine levels were determined in plasma samples from 99 women selected on the basis of race (black versus white) and quartile of the WHR (1st versus 4th). Of a panel of 20 organochlorine compounds tested, only DDE was detectable in most study subjects. Measurements of height, weight, and waist and hip circumferences were taken during an in-person interview. Information was elicited regarding dietary, residential, and breast-feeding histories. Results of multiple regression analyses indicate that black women had significantly higher plasma levels of DDE than white women. These levels were independent of BMI and WHR. BMI but not WHR was also found to be an independent predictor of DDE plasma level. These results suggest that black/white differences should be considered in studies that explore the relationship between environmental contaminants and various disease outcomes, such as breast cancer risk. In addition, BMI may affect circulating levels of contaminants and should also be considered a potentially important modifying factor for exposure to lipophilic substances.

Aged↗
PubMed1999

Physiologic changes in humans subjected to severe, selective calorie restriction for two years in biosphere 2: health, aging, and toxicological perspectives.

Biosphere 2 is a closed ecological space of 7-million cubic feet near Tucson, AZ, containing 7 biomes: rain forest, Savannah, ocean, marsh, desert, agricultural station, and habitat for humans and domestic animals. Sealed inside, 4 men and 4 women maintained themselves and the various systems for 2 years. All organic material, all water, and nearly all air was recycled, and virtually all food was grown inside. On the low calorie but nutrient-dense diet available, the men sustained 18% and the women 10% weight loss, mostly within the first 6 to 9 months. The nature of the diet duplicated rodent diets that had been shown to enhance health, lower disease incidence, and retard aging. Using blood specimens frozen at different points during and after the 2 years, determinations were made of a number of biochemical parameters judged to be pertinent based on past studies of rodents and monkeys on similar diets. These included blood lipids, glucose, insulin, glycosylated hemoglobin, renin, and others. The results clearly suggest that humans react to such a nutritional regime similarly to other vertebrates. In addition to these studies, and because this was a tightly closed, isolated environment, the levels of insecticides or pollutants or their derivatives were determined in the sera of 2 crew members. It was found that levels of the lipophilic toxicant DDE and the "total PCB" load increased with the loss of body fat during the first 12-18 months inside Biosphere 2, then decreased.

Adult↗
PubMed1984

Human absorption of crude coal tar products.

Five normal adult volunteers without cutaneous disease applied 2% crude coal tar to the skin for eight-hour periods on two consecutive days. Blood extracts subjected to gas chromatography and mass spectrometry yielded evidence of absorption in all five volunteers. Phenanthrene, anthracene, pyrene, and fluoranthene, found in four of our volunteers, have been shown to be tumor initiators or cocarcinogens.

Adult↗
PubMed1978

Mass spectra of the oxygenated products generated from phenanthrene under simulated environmental conditions.

The photooxidation of phenanthrene under stimulated environmental conditions to 9,10-epoxy-9,10-dihydrophenanthrene, among other oxygenated products, serves as a model for the conversion of polycyclic aromatic hydrocarbons to potentially mutagenic and/or carcinogenic products. The separation and identification were achieved by glass capillary gas chromatography mass spectrometry, and by comparison of gas chromatographic retention times and mass spectral fragmentation patterns with data observed for authentic samples obtained independently through synthesis or from commercial sources. The structural rearrangements of 2,2'-di-substituted biphenyls such as 2-formyl biphenyl-2'-carboxylic acid, 2,2' diformyl biphenyl and diphenic acid anhydride, induced upon electron impact are investigated and discussed in detail. The mass spectral comparison of 9,10-epoxy-9,10-dihydrophenanthrene, a primary mammalian metabolite of phenanthrene, and certain other structural isomers was conducted and the results of this study suggest a mass spectral technique capable of differentiating arene oxides from oxepin, phenol and carbonyl isomers. A discussion of the potential impact of the sensitized photooxidation of more condensed environmental polycyclic aromatic hydrocarbon pollutants is presented and the role of bioactive arene oxides produced under such photooxidation conditions is also discussed. Related oxides of polycyclic aromatic hydrocarbons are known to be proximate carcinogens and/or mutagens generated by metabolic activation. The role and significance of solar induced oxidation in the weathering of petroleum hydrocarbons at air-sea interfaces and the incorporation of potentially bioactive organic residues in the food chain are also addressed.

Biphenyl Compounds↗
PubMed1977

Application of glass capillary columns to monitor petroleum-type hydrocarbons in marine sediments.

High resolution glass capillary columns coated with SE 52 liquid phase were used to resolve the indigenous hydrocarbons extracted from sediment samples collected from three outer continental shelf areas. The extracts were than spiked with small amounts of aliphatic or aromatic components isolated from a Louisiana crude oil and rechromatographed. The resolution was sufficient to separate almost all the isoprenoid, branched and cyclic alkanes associated with petroleum. Additionally, many of the key petroleum aromatics could also be resolved from naturally occurring organics. Such chromatographic procedures will aid in distinguishing between indigenous hydrocarbons of contemporary origin and those known to be associated with fossil hydrocarbon pollution of marine sediments.

Chromatography, Gas↗
PubMed1976

Gas chromatographic mass spectrometric evaluation of free organic acids in human saliva.

Excellent resolution and subsequent identification of free organic acids extracted from mixed, unstimulated human saliva was obtained by gas chromatography using high resolution open tubular glass capillary columns coupled with mass spectrometry computer instrumentation. In addition to the organic acids, identified as their trimethylsilyl derivaties, the presence of 2,6-di-t-butylcresol--a food preservative--and cholesterol was established by mass spectrometry. The effects of aspirin ingestion as well as diurnal variation were studied to demonstrate the possible clinical significance of this noninvasive approach to metabolic profiling.

Acids↗
PubMed1976

Application of a computer-based chromatograph for automated water pollution analyses.

A modified head-space analysis technique, coupling thermal extraction with subsequent adsorption of organics on a poly (para 2,6-diphenyl phenylene) oxide adsorbent (Tenax-GC), has been found to be an efficacious tool when combined with gas chromatography for the study and monitoring of low molecular weight organics present in drinking water supplies (1-4). This procedure has allowed for the analysis of volatile organics in the low parts-per-billion range from 1 liter or less of tap water. Because thermal extraction requires smaller sample sizes than required in carbon-chloroform extraction methods and liquid/liquid extractions, the EPA has recently adopted this type of methodology (5,6). Passage of the Safe Water Drinking Act in December of 1974 has mandated that each state assumes the primary responsibility for carrying out the purposes of the legislation (7). Because the Act says that any supplier of water serving 25 individuals or more must comply with these regulations, large-scale monitoring programs will have to be undertaken. It was thus our desire to try to simplify the sample collection and data acquistion and reduction processes as much as possible, in the effort to make the procedure more adaptable for incorporation into routine monitoring programs. Also, automation reduces the experience and number of personnel required to perform the analyses. In addition to analysis of drinking water samples, the automated procedure described hereinafter can also be applied to monitoring industrial plant effluents, waste water treatment processes, and general quality control monitoring of low molecular weight organic compounds.

Autoanalysis↗
PubMed1976

The transplacental migration and accumulation in blood of volatile organic constituents.

Gas chromatographic-mass spectrometric analysis of profiles of low molecular weight volatile organic constituents obtained from cord blood and maternal blood samples collected at birth reflect transplacentally acquired compounds. The transplacental passage of halogenated hydrocarbons, plastic components, and abnormal accumulations of compounds have been demonstrated. In the 11 paired cord blood-maternal blood samples analyzed, the relative amounts of constituents in cord blood closely correspond to those quantities present in the maternal blood. However, some of the over 100 components are present in the cord blood in significantly higher concentrations than in the maternal blood, suggesting a possible selective one-way transfer of certain constituents into the fetus. Benzene, carbon tetrachloride, and chloroform are present in quantities equal to or greater than in maternal blood. In one infant with a lumbosacral meningomyelocele abnormally high concentrations of acetone, other components, and the food preservative 2, 6-di-tert-butyl-4-methylphenol (BHT) were identified.

Benzene↗
PubMed1976

Use of gas chromatography and mass spectrometry to analyze underivatized volatile human or animal constituents of clinical interest.

The study of volatilizable components in human and animal samples by gas chromatography and mass spectrometry is reviewed for the years 1970--1975. Only naturally volatile, underivatized compounds are considered, from sources such as body fluids, tissues, and breath. Where possible, the clinical samples are discussed in terms of normal profiling, aberrations associated with disease states, and specific compound analyses. A brief descriptive technical section is included, stressing types of sample preparation currently being used.

Anesthetics, Local↗