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Biomedical subjects

M P Maskarinec

Publications and source records attributed to M P Maskarinec.

14 recordsLinked to original sources
PubMed2004

Reductive transformation of methyl parathion by the cyanobacterium Anabaena sp. strain PCC7120.

Organophosphorus compounds are toxic chemicals that are applied worldwide as household pesticides and for crop protection, and they are stockpiled for chemical warfare. As a result, they are routinely detected in air and water. Methods and routes of biodegradation of these compounds are being sought. We report that under aerobic, photosynthetic conditions, the cyanobacterium Anabaena sp. transformed methyl parathion first to o,o-dimethyl o-p-nitrosophenyl thiophosphate and then to o,o-dimethyl o-p-aminophenyl thiophosphate by reducing the nitro group. The process of methyl parathion transformation occurred in the light, but not in the dark. Methyl parathion was toxic to cyanobacteria in the dark but did not affect their viability in the light. Methyl parathion transformation was not affected by mutations in the genes involved in nitrate reduction in cyanobacteria.

Aerobiosis↗
PubMed2001

Environmental tobacco smoke in the nonsmoking section of a restaurant: a case study.

This study tested the concentrations of environmental tobacco smoke (ETS) components in a small restaurant/pub with smoking and nonsmoking areas-a facility outfitted with a heat-recovery ventilation system and directional airflow. The ETS levels in the nonsmoking area were compared with those in other similar restaurants/pubs where indoor smoking is altogether prohibited. The results indicate that ETS component concentrations in the nonsmoking section of the facility in question were not statistically different (P < 0.05) from those measured in similar facilities where smoking is prohibited. The regulatory implications of these findings are that ventilation techniques for restaurants/pubs with separate smoking and nonsmoking areas are capable of achieving nonsmoking area ETS concentrations that are comparable to those of similar facilities that prohibit smoking outright.

Air Pollutants↗
PubMed1987

Separation of modified nucleic acid constituents by micellar electrokinetic capillary chromatography.

Micellar electrokinetic capillary chromatography offers a high-resolution microanalytical technique useful for adducted and modified nucleic acid constituents. A mixture of 14 normal and modified deoxyribonucleosides, deoxyribomononucleotides, a ribonucleoside and a pyrimidine can be resolved in less than 40 min using 10 kV of separating voltage, 0.075 M sodium dodecylsulfate micelles in phosphate-borate buffer, and a 68.5 cm X 60 micron I.D. fused-silica column. Efficiencies up to 370,000 theoretical plates (540,000 plates/m) are achieved, but are highly dependent on solute concentration. The limit of detection for 2'-deoxyguanosine under high-resolution conditions is ca. 18 pg at a signal-to-noise ratio of 4, but the very small injection volumes (ca. 1.5 nl) limit the minimum detectable sample solution concentration to ca. 42 nmol/ml.

Chromatography, Liquid↗
PubMed1986

Analysis of B6 vitamers by micellar electrokinetic capillary chromatography with laser-excited fluorescence detection.

Micellar electrokinetic capillary chromatography (MECC) involves the application of a high voltage (10 to 40 kV) across a capillary column (25 to 75 microns i.d.) that is filled with a solution containing micelles. The mobile phase in this work consists of sodium dodecyl sulfate in an aqueous phosphate/borate buffer system. Pyridoxine (vitamin B6) and five of its metabolites are separated, with efficiencies as high as 60,000 theoretical plates/meter. Pyridoxic acid, a metabolite of B6, is separated and quantitated in human urine using laser-excited fluorescence detection. Limits of detection are less than a picogram injected.

Chromatography, Liquid↗
PubMed1985

Dynamically modified capillary columns for liquid chromatographic separations of biological compounds.

Dynamically modified open tubular capillary columns were evaluated for separations of biological and clinical interest. Small diameter, dynamically modified columns were readily prepared by simple addition of cetyltrimethylammonium salts to the mobile phase. Separations similar to those obtained on conventional reversed-phase columns were observed for neutral solutes, and ion-pair reversed-phase separations were observed for charged solutes. Borosilicate and standard flint glasses were evaluated with respect to common etching procedures. A potential clinical application is presented in the separation of antitumor drugs.

Antineoplastic Agents↗
PubMed1984

Pharmacological activity of the basic fraction of marihuana whole smoke condensate alone and in combination with delta-9-tetrahydrocannabinol in mice.

This basic fraction (BF) of marihuana whole smoke condensate was subjected to pharmacological testing in males, Swiss-Webster mice. In a general pharmacological activity screen looking at behavioral, neurologic, and autonomic parameters, BF, at iv doses of 5, 10, and 20 mg/kg, caused impairment of visual placing, increase in tail pinch response, decrease in tail elevation, and induction of piloerection. These effects, although statistically significant, were slight and not consistently dose dependent. In a second study with doses ranging from 10 to 29 mg/kg, BF caused a decrease in spatial locomotion, rearing behavior, and urination incidence. In a third study, body temperatures of mice were measured periodically for 2 hr following administration of BF (1.2, 2.4, and 4.8 mg/kg) alone or in combination with 1.0 mg/kg delta-9-tetrahydrocannabinol (THC). BF did not alter body temperature, nor did it affect THC-induced hypothermia. These results, although suggesting that the basic fraction of marihuana whole smoke condensate has pharmacological activity in mice, offers little evidence for the presence of highly active compounds.

Animals↗
PubMed1984

Liquid chromatography in open tubes.

Liquid chromatography in open tubes is evaluated for applicability to clinical analysis. The principal advantages of this technique include high separation power, reduced solvent consumption, and small sample volume requirements. Technology for the production of columns as small as 8 micron (i.d.) is described. Preliminary results are encouraging and, with further development in column and detector technology, the technique should find wide applicability in clinical analysis.

Chromatography, Liquid↗
PubMed1976

Analysis of the acidic fraction of marijuana smoke condensate by capillary gas chromatography-mass spectrometry.

A method for the analysis of organic acids and phenols isolated from marijuana smoke condensate has been developed. Comparative analyses of standard tobacoo, Mexican, and Turkish marijuana smoke condensates carried out by means of capillary gas chromatography indicated both qualitative and quantitative changes in the constituents of chromatographic profiles. Samples were converted to volatile derivatives by methylation and trimethylsilylation; whereupon, 49 aliphatic acids, aromatic acids, and phenolic compounds were identified by means of capillary gas chromatography-mass spectrometry.

Acids↗
PubMedDate not supplied

Determination of exposure to environmental tobacco smoke in restaurant and tavern workers in one US city.

Approximately 173 subjects employed as waiters, waitresses, or bartenders in the Knoxville, TN, Standard Metropolitan Statistical Area collected a sample of air from their breathing zone while at their workplace for one shift. In addition, area samples were placed near the work spaces of many of the subjects. Collected samples were analyzed for respirable suspended particulate matter (RSPM), ultraviolet-absorbing and fluorescing particulate matter, solanesol, 3-ethenyl pyridine (3-EP), and nicotine. Saliva samples were collected from the subjects prior to and within 24 h following their work shift, to confirm their non-smoking status. The range of concentrations of environmental tobacco smoke (ETS) constituents encountered was considerable, e.g., for nicotine, from undetectable to more than 100 microg/m3. However, the highest RSP levels observed were considerably lower than OSHA workplace standards. Distributions of ETS concentrations suggest that there are two "ETS exposure" types of bartenders: those that work in single room bars and those that work in larger, multiroom restaurant/bars. Personal exposure to ETS of the former group was ca. 10x greater than those of the latter group, who were exposed to ETS levels more comparable to those encountered by wait staff. Exposure (concentration x duration) differences between wait staff and workers in other types of unrestricted smoking environments reported in other studies suggest that exposures in the restaurant environment may be more difficult to assess than originally considered. Salivary cotinine levels indicated that for those subjects living in smoking homes, ETS exposures outside the workplace are at least as important as those in the workplace.

Adolescent↗
PubMedDate not supplied

Environmental tobacco smoke in an unrestricted smoking workplace: area and personal exposure monitoring.

The objective of this investigation was to determine the extent of areal and day-to-day variability of stationary environmental tobacco smoke (ETS) concentrations in a single large facility where smoking was both prevalent and unrestricted, and to determine the degree of daily variation in the personal exposure levels of ETS constituents in the same facility. The subject facility was a relatively new four-story office building with an approximate volume of 1.3 million ft3. The exchange of outside air in the building was determined to be between 0.6 and 0.7 air changes per hour. Eighty-seven area samples (excluding background) were collected at 29 locations over the course of 6 days of sampling. Locations included offices and cubicles occupied by smokers and nonsmokers, common areas, and the computer and mail rooms. Twenty-four nonsmoking subjects wore personal sampling systems to collect breathing zone air samples on each of 3 days in succession. This generated a total of seventy-two 8-h time-weighted average (TWA) personal exposure samples. In all samples, respirable suspended particulate matter, ultraviolet light-absorbing and fluorescing particulate matter, solanesol, nicotine, and 3-ethenyl pyridine were determined. With the exception of a few locations, tobacco-specific airborne constituents were determined in all samples. Not surprisingly, areas with the highest ETS constituent concentrations were offices and cubicles of smokers. Median and 95th percentile concentrations for all area samples, excluding background, were determined to be 1.5 and 8.7 microg/m3 for nicotine, and 8.2 and 59 microg/m3 for ETS-specific particles (as solanesol-related particulate matter, Sol-PM), respectively. Personal exposure concentrations of ETS components were similar to those levels found in the area samples (median nicotine and Sol-PM concentrations were 1.24 and 7.1 microg/m3, respectively), but the range of concentrations was somewhat smaller. For example, the 95th percentile 8-h TWA nicotine and ETS-specific particle (as Sol-PM) concentrations were 3.58 and 21.9 microg/m3, respectively. Intrasubject variation of daily concentrations ranged from 20% to 60%, depending on the component. Self-reported proximity to smokers was supported by higher ETS concentrations determined from the personal monitors, but only to a modest extent. Although smoking was completely unrestricted inside the main office areas of the facility, ETS levels, either areal or from personal exposure measurements, were lower than those estimated by Occupational Safety and Health Administration to be present in such facilities.

Environmental Exposure↗