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Biomedical subjects

L L Needham

Publications and source records attributed to L L Needham.

At least 91 records · Page 5Linked to original sources
PubMed1982

Electron-capture, capillary column gas chromatographic determination of low-molecular-weight diols in serum.

Research on alcoholism has revealed that concentrations of 1,2-propanediol, d,1-2,3-butanediol and meso-2,3-butanediol may be greater in the serum of chronic alcoholics than in the serum of social drinkers and nondrinkers. In connection with one of these studies, we developed methodology to determine these diols at the micromolar levels in 500 serum samples. The procedure consisted primarily of extraction of the serum with acetonitrile containing internal standard. The extract was then concentrated to dryness and reacted with p-bromophenylboric acid. The reaction mixture was injected into a gas chromatograph fitted with a capillary column and an electron-capture detector. The total coefficients of variation were best for 1,2-propanediol, 6.82 and 10.00%, and worst for d,1-2,3-butanediol, 13.64 and 19.22%. The observed means for the analytes were all within 10% of the spiked level.

Alcoholism↗
PubMed1982

Development and utilization of a procedure for measuring urinary porphyrins by high-performance liquid chromatography.

We describe a procedure for determining the five principal urinary porphyrins--uroporphyrin, heptacarboxylporphyrin, hexacarboxylporphyrin, pentacarboxylporphyrin, and coproporphyrin--by using high-performance liquid chromatography (HPLC). The method involves a 12- to 15-min isocratic separation on a Bondapak Phenyl column. Studies have indicated that urine samples must be preserved to maintain porphyrin stability for extended periods. We have found that the pH of preserved samples must be adjusted into the acidic range before the samples can be accurately analyzed by this HPLC procedure. Our studies demonstrate that good reproducibility and recovery are achieved with this method. Urinary porphyrin values for normal and porphyric individuals are reported.

Chromatography, High Pressure Liquid↗
PubMed1982

Evidence of degradation of polybrominated biphenyls in soil samples from Michigan.

Soil samples obtained from the former polybrominated biphenyls (PBB) manufacturing site in Michigan were analyzed by gas chromatography and gas chromatography with mass spectrometric detection. The results indicate significant degradation of the PBB residue in the soil sample. The soil sample with the highest concentration of PBB had the greatest degree of degradation. Principal degradation products include 2,3', 4,4', 5-pentabromobiphenyl, 2,2', 4,4', 5-pentabromobiphenyl and two unidentified tetrabromobiphenyls. The degradation pattern observed supports a photochemical decomposition mechanism. These degraded residues may be more toxic than the original Firemaster residues. The implications of the results are discussed.

Biodegradation, Environmental↗
PubMed1981

Hyperkeratosis induced by sunlight degradation products of the major polybrominated biphenyl in Firemaster.

Sunlight photodegradation of 2,2', 4,4', 5,5' -hexabromobiphenyl, the major component of Firemaster, gave a mixture that produces severe hyperkeratosis of the rabbit ear. This component in its pure state does not cause hyperkeratosis. One or more of the four major photolysis products must be responsible for this activity. A similar photodegradation pattern was observed for 2,2', 3,4,4', 5,5' -heptabromobiphenyl, the second largest component of Firemaster.

Animals↗
PubMed1981

Association of blood pressure and polychlorinated biphenyl levels.

The geometric mean serum level of polychlorinated biphenyls (PCBs) of 458 persons in a communitywide study was 17.2 microgram/L, with 80% to 90% having levels within the range found in other community groups. As a dependent variable, PCB levels were found to be positively related to age, even when controlled for all other variables associated with PCB level: sex, local fish consumption, obesity, serum cholesterol level, and alcohol consumption. No major point source of PCB contamination was found, and fish taken in the drainage of a major population center had mean PCB levels below the current enforceable Food and Drug Administration tolerance of 5 mg/kg. As an independent variable, serum PCB levels were positively associated with gamma-glutamyl transpeptidase level, serum cholesterol level, and measured blood pressure. The PCB-blood pressure association, which was independent of age, sex, body mass index, and social class, must be confirmed in other exposed populations.

Alabama↗
PubMed1981

Cross-sectional study of a community with exceptional exposure to DDT.

The geometric mean level of total DDT in serum samples (76.2 ng/mL) from 499 persons living downstream from a defunct DDT-manufacturing plant was several times the national geometric mean (15.0 ng/mL). DDE isomers, metabolites of DDT, accounted for an average of 86.7% of total DDT. Total DDT levels increased with age, even when controlled for other independent variables also significantly associated with DDT: race, sex, fish consumption, years of residence, socioeconomic status, alcohol consumption, and serum triglyceride levels. Fish consumption, the second strongest determinant of DDT level, had one third the predictive power of age. Total DDT levels were not associated with specific illness or ill health. However, total DDT levels were positively associated with levels of serum cholesterol, triglyceride, and gamma-glutamyl transpeptidase. The finding that serum DDE levels increase with age suggests that no equilibrium in body burden has been reached or that pharmacokinetics or serum/adipose partition may vary with age.

Adolescent↗
PubMed1981

Temperature-programmed gas chromatographic determination of polychlorinated and polybrominated biphenyls in serum.

An analytical method was developed to quantitate polychlorinated and polybrominated biphenyls (PCBs and PBBs, respectively) in human serum. The method includes denaturation of the proteins in serum, extraction, adsorption chromatography, and gas chromatography with electron capture detection. The coefficients of variation for determining the in vivo bound PCBs and PBBs ranged from 11.7 to 29.8% and 7.1 to 14.0%, respectively. The method is capable of measuring 10 ng PCBs and PBBs/mL in 4 mL serum.

Biphenyl Compounds↗
PubMed1980

Metabolic consequences of exposure to polychlorinated biphenyls (PCB) in sewage sludge.

Polychlorinated biphenyls (PCB) were discovered in sewage sludge used for fertilizer in Bloomington, Indiana. The PCB had been discharged into the municipal sewage system by an electrical capacitor manufacturing plant. To study the epidemiology and metabolic consequences of PCB exposure an epidemiologic and clinical survey was conducted. Mean serum PCB levels were 17.4 ppb in 89 sludge users, 75.1 ppb in 18 workers with occupational exposure to PCB, 33.6 ppb in 19 members of those workers' families, and 24.4 ppb in 22 community residents without unusual exposure to PCB. In sludge users PCB levels were associated positively with per cent performance of garden care (p = 0.035) and negatively with wearing gloves while gardening (p = 0.021), but were not significantly associated with the amount of sludge used or the duration of exposure. In no groups were chloracne or systemic symptoms of PCB toxicity noted, nor were significant correlations found between PCB levels and tests of hematologic, hepatic, or renal function. Plasma triglyceride levels increased significantly with serum PCB concentrations in both alcohol drinkers and nondrinkers (r = 0.541, n = 36, p < 0.001 for nondrinkers). These data indicate that PCB may alter lipid metabolism at levels of exposure and bioaccumulation insufficient to produce overt symptoms.

Agriculture↗
PubMed1979

Determination of paraquat in sunflower seeds by reversed-phase high-performance liquid chromatography.

The herbicide paraquat was determined with extracts from 1-g samples of sunflower seeds. The liquid chromatography procedure utilized a microparticle (10 micron) C18 reversed-phase column and isocratic elution with 27% acetonitrile in water, 10 mM in the sodium salt of octanesulfonic acid. Eluted paraquat was detected at 254 and 280 nm and quantitated by paraquat internal standard peak height ratios. This procedure provided linear working curves over the concentration range of 0-20 microgram/g of paraquat. Recovery of paraquat varied from 89-101%, with an average recovery of 93%. Good agreement was obtained in the comparison of results of the described procedure with those from a well established UV procedure.

Chromatography, High Pressure Liquid↗
PubMed1979

A fatal episode of accidental methomyl poisoning.

Three fatalities from the accidental ingestion of methomyl, a carbamate pesticide, are reported. The methomyl had been stored in an unlabeled tin can and was accidentally used in preparing "roti," an Indian dish. The identification of the source of the poison through animal tests and further chemical identification is described. The lethal dose of methomyl was estimated to have been between 12 and 15 mg/kg body weight.

Accidents↗