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Biomedical subjects

R C Dougherty

Publications and source records attributed to R C Dougherty.

17 recordsLinked to original sources
PubMed1987

Phthalate esters and semen quality parameters.

Analysis of reports in the world's literature suggests that average sperm densities for groups of unselected males were relatively constant at about 108 million cells per ml prior to 1950. Subsequent to that time mean sperm densities appear to have declined. Regression analysis indicates the existence of significant negative correlations between mean sperm densities and production of synthetic organic chemicals among other parameters. Phthalate esters are one class of large volume organic chemicals that are known to disturb testicular function in laboratory animals. These compounds are also the most abundant man-made chemicals in the environment. Plots of the concentration of dibutylphthalate in the cellular fraction of ejaculates against either the sperm density or the total number of sperm for the same ejaculates gave two clusters of points. These clusters suggest the existence of two or more populations vis à vis phthalate metabolism; both of which show a negative correlation between phthalate concentration and sperm production.

Dibutyl Phthalate↗
PubMed1981

Tris(dichloropropyl)phosphate, a mutagenic flame retardant: frequent cocurrence in human seminal plasma.

Negative-chemical-ionization mass spectral screening of extracts of human seminal plasma has revealed a presence of a Cl7 ion cluster at a mass-to-charge ratio (m/z) of 463 in a significant number of the samples examined (34 out of 123). Experiments with different gases used to generate the negative-chemical-ionization plasma indicated that the ion at m/z 463 was a chloride adduca of a Cl6 molecule with a mass of 428 daltons. Negative-chemical-ionization mass measurement with ions from the iodoform mass spectrum used as reference peaks gave a mass of 427.882 daltons; C9H15PCl6 has a molecular weight of 427.883. Extraction of polyurethane foam with toluene produced an extract that consistently gave a negative-chemical-ionization spectrum containing an intense Cl7ion at m/z463. The component producing ion was isolated, and its proton nuclear magnetic resonance spectrum confirmed that it was tris (1,3-dichloro-2-propyl)phosphate, a mutagenic flame retardant. The negative-chemical-ionization screening evidence suggests that this flame retardant or its isomer tris(2,3-dichloro-l-propyl)phosphate, or both, are absorbved into the body from formulations in which they are used as flame retardants. Remedial action seems indicated to reduce human exposure to these compunds.

Environmental Exposure↗
PubMed1981

Detection of urinary primary amines through negative chemical ionization mass spectrometry of fluorescamine derivatives.

We report the successful detection of urinary biogenic amines by a procedure which involves isolation of the amines on CG-50 cation exchange resin, derivatization of the amines with fluorescamine while on the resin, followed by direct probe negative chemical ionization mass spectrometry screening of the resin extract. This isolation procedure allowed the detection of tyramine, octopamine, normetanephrine, 3-methoxytyramine and a variety of aliphatic amines. Norepinephrine, dopamine and serotonin were chemically reactive under these conditions and were not detectable at physiological concentrations.

Biogenic Amines↗
PubMed1980

Self-assembled chlorophyll a systems as studied by californium-252 plasma desorption mass spectroscopy.

Self-assembled chlorophyll a and pheophytin a systems in thin solid films have been studied by (252)Cf plasma desorption mass spectrometry (PDMS). The (252)Cf-PDMS spectra of these films show monomer cation and anion molecular ions, ions of molecular aggregates, and positive and negative ion fragmentation patterns arising from the loss of various aliphatic side chains from the chlorin ring. Chlorophyll a films cast from dry carbon tetrachloride solution, in which chlorophyll a is known to occur as the dimer, produced an abundant dimer ion. The highest degree of chlorophyll a self-assembly was observed in chlorophyll a films cast from n-octane solutions. Oligomer ions extending upwards in size to the heptamer were detected in this system.

Journal Article↗
PubMed1980

Negative chemical ionization studied of human and food chain contamination with xenobiotic chemicals.

Negative chemical ionization mass spectrometry with a mixture of isobutane, methylene chloride, and oxygen as the reagent gas has been used to explore contamination of environmental substrates with xenobiotic chemicals. The substrates in question, fish tissue, human seminal plasma, and human adipose tissue, were cleaned up by one of the following three cleanup procedures: (1) continuous liquid-liquid extraction steam distillation; (2) gel-permeation chromatography; and (3) adsorption on activated carbon followed by elution with toluene. The third procedure was used only for the examination of planar polychlorinated aromatic hydrocarbons in environmental samples. Using these techniques, we have found evidence for contamination of fish samples with polychloronaphthalenes, polychlorostyrenes, polychlorobiphenyls, polychlorodibenzofurans, and polychlorodibenzodioxins among other chemicals. The polychlorodibenzodioxins appeared only in the spectra of extracts of fish obtained from the Tittabawassee River at Midland Michigan. The polychlorodibenzofuran ions appeared in NCI mass spectra of fish that were significantly contaminated (above 2 ppm) with polychlorobiphenyls. Toxic substances occurring in human seminal plasma included pentachlorophenol, hexachlorobenzene, DDT metabolites, and polychlorobiphenyls. We have investigated toxic substances in human seminal plasma because of the apparent decrease in sperm density in U.S. males over the last 30 years. Results of screening human adipose tissue for contamination with xenobiotic chemicals have been largely coincident with result of the EPA human monitoring program. Polychlorobiphenyls, DDT metabolites, nonachlor, and chlordane have appeared in most samples examined. Detection limits for all of these chemicals were of the order of 1 ppb.

Adipose Tissue↗
PubMed1978

Children absorb tris-BP flame retardant from sleepwear: urine contains the mutagenic metabolite, 2,3-dibromopropanol.

The flame retardant, tris(2,3-dibromopropyl)phosphate (tris-BP), which is a mutagen and causes cancer and sterility in animals is absorbed from fabric by people. 2,3-Dibromopropanol, a metboloite of tris-BP and a mutagen itself, has been found in the urine samples of ten children who were wearing or who had worn tris-BP-treated sleepwear. Eight of these children were wearing well-washed sleepwear and the possibility of absorption of tris-BP from well-washed sleepwear discussed. 2,3-Dibromopropanol was not found in the urines of one child and one adult who had never worn tris-BP-treated garments.

1-Propanol↗
PubMed1976

Screening by negative chemical ionization mass spectrometry for environmental contamination with toxic residues: Application to human urines.

A screening procedure based on solvent extraction with minimal clean up followed by examination with negative chemical ionization mass spectrometry has been developed for organochlorine residues and related compounds with masses greater than 130 daltons. The procedure has been made quantitative for analysis of pentachlorophenol residues. A limited survey of human urines indicated extensive contamination of the subjects, studied at parts per billion and higher levels, with pentachlorophenol, 2, 4, 5-trichlorophenoxy acetic acid, other polychlorophenoxy acids, and numerous unknown compounds. In an attempt to define the source of the contamination, the screening procedure was applied to samples of environmental substrates. The results suggest the food chain as one significant source of the contamination. A preliminary study of organochlorine compounds in human seminal fluid showed pentachlorophenol and other organochlorine residues in every sample, a result which suggests that this area may merit additional monitoring.

Humans↗
PubMed1976

Multiresidue screening by negative chemical ionization mass spectrometry of organic polychlorides.

A multiresidue procedure, based on negative chemical ionization (NCI) mass spectrometry, for analyzing organochlorine residues in environmental substrates is described. The procedure is capable of routinely detecting about 1 ng unknown organochlorine residues. Semi-quantitative data (order of magnitude) may be obtained for pentachlorophenol and 2,4,5-trichlorophenoxyacetic acid residues by calibration with internal p-chlorobenzophenone. Lipid-rich substrates were resolved into acidic and neutral fractions, and both fractions were further purified by gel permeation chromatography (GPC) prior to NCI analysis. In spite of the fact that recoveries were often low, the overall sensitivity for residues in lipid-rich substrates appeared to be higher than when the GPC step was omitted.

Animals↗
PubMedDate not supplied

Chemical geometrodynamics: physical fields can cause asymmetric synthesis.

This paper presents theoretical arguments that suggest that chiral combinations of physical fields which can induce motion of elementary particles or molecular systems can in principle cause asymmetric synthesis. The theory is founded on the application of parity and time reversal operators to chiral dynamical systems. The motion of these systems induced by a chiral set of physical fields is shown not to be invariant on parity and time reflection. The relationship between tetrahedral dissymmetry and helical dissymmetry is analyzed in terms of the moments of inertia of a tetrahedrally dissymmetric rotor rotating around each of the four bond axes. The magnitude of anticipated enantiomeric excess which would result from conducting a prochiral chemical reaction in a chiral set of physical fields is estimated to be very small, parts per million or less, for virtually all sets of readily accessible physical fields. The results of experiments in which prochiral chemical reactions were conducted in a sealed tube which was spinning perpendicular or parallel to the earth's surface, are reviewed as are experiments in which prochiral chemical reactions were conducted in intense oriented magnetic fields. Enantiomeric recognition may have been one of the principal mechanisms for amplifying small differences in the rates of a given prochiral chemical reaction.

Chemical Phenomena↗
PubMedDate not supplied

Toxic environmental chemicals in human semen: analytical method and case studies.

In 1982, 89 men from all over the FRG participated in an investigation of sperm density and the presence of selected persistent environmental chemicals in their semen. Semen concentrations for the following chemicals were measured: lead, cadmium, hexachlorobenzene (HCBC), a-hexachlorocyclohexane (a-BHC), DDT and metabolites, dieldrin and polychlorobiphenyls (PBC). Heavy metal analyses were performed by Zeeman-AAS with direct sample measurement. A method for the quantitative determination of chlorinated hydrocarbons in semen by liquid-liquid extraction, clean-up and quantitation by gas chromatography with an electron capture detector. Recovery rates ranged from 72 to 120%. Compound identification in samples was confirmed by negative chemical ionization mass spectrometry. Heavy metals and organochlorine compounds in semen were present in the same concentration range as in blood or other biofluids. Occupational exposure as well as extraordinary environmental exposure appeared to influence semen concentrations. Students in chemistry showed elevated levels of organochlorine compounds. Men who lived in the vicinity of an atmospheric source of heavy metals showed strikingly the vicinity of an atmospheric source of heavy metals showed strikingly elevated levels of semen lead and cadmium. We were unable to find a statistically significant correlation between sperm density and any of the variables examined in this study including: orgonochlorine compounds summed or individually; lead and/or cadmium; and tobacco consumption. Significant correlations were found between the simultaneous occurrence of lead and cadmium and between the simultaneous occurrence of HCB, DDT and DDE.

Adult↗