Search PubMed⌕ Search

Biomedical subjects

D Tierney

Publications and source records attributed to D Tierney.

11 recordsLinked to original sources
PubMed2006

Electron spin resonance and raman scattering spectroscopy of multi-walled carbon nanotubes: a function of acid treatment.

We compare the fundamental transport mechanism in multi-walled carbon nanotubes (MWNTs) by means of electron spin resonance (ESR) and Raman spectroscopy as a function of acid treatment. The ESR and Raman results show that the acid treatment reduces the density of states at the Fermi level. Defects introduced through the acid treatment move the Fermi level closer to the K points in the valence band, and consequently conduction is reduced. These defects are identified as Stone-Wales type from the Raman results.

Carbon↗
PubMed2000

8:45-90:00. The Influence of a High Fat Meal Compared to an Olestra Meal on Coronary Artery Endothelial Dysfunction by Rubidium (Rb)-82 Positron Emission Tomography (PET) and on Post Prandial Serum Triglycerides.

Background: Cellular changes lead to coronary artery endothelial dysfunction (ED) and precede plaque formation. Clinical events, such as unstable angina and acute coronary syndromes, are common consequences of ED. Coronary artery ED, as characterized by Rb-82 PE, is a perfusion abnormality at rest, which improves following stress. In risk factor modification studies, particularly in cholesterol-lowering trials, coronary artery ED has been demonstrated to be reversible. Other studies have correlated low fat diet modification with improvement in coronary artery disease.Purpose: This study evaluates changes in myocardial perfusion following meals with low versus high TG content, and its influence on post prandial serum TG.Methods: With a randomized, double blind placebo controlled, cross over design, we investigated 19 patients (10 with ED and 9 with normal perfusion) with Rb-82 PET for myocardial blood flow at rest and with adenosine stress. PET images and serum triglycerides were obtained before and after an olestra (OA) meal (2.7g TG, 44g olestra) and a high-fat meal (46.7g TG). Meals were matched for carbohydrate, protein, and cholesterol content.Results: Myocardial perfusion (uCi/cc) increased 11 - 12% following the OA meal compared to the high-fat meal in patients with ED. For all patients combined, serum TG increased significantly (p < 0.01) in the non-OA group with the median change from baseline to 170.0 mg/dl, compared to 21.5 mg/dl in the OA group during the 6 hours following the meal.Conclusions: A single olestra meal significantly diminishes post prandial serum TG levels and improves myocardial perfusion in patients with endothelial disease.

Journal Article↗
PubMed1999

Release of atrazine ((14)C) from two undisturbed submerged sediments over a two-year period.

Through water erosion and runoff, sediment-adsorbed atrazine can undergo sedimentation and accumulation at the bottom of water bodies and become potential sources of atrazine to the water column. The purpose of this study is to determine the fate and release of atrazine ((14)C) to the water column from two simulated undisturbed submerged sediments at two temperature treatments (5 and 24 degrees C) over a 2-year period. Atrazine residue ((14)C) was released from the two sediments and was, primarily, diffusing from the sediment pore water to the water columns. The amount released was affected by sediment type and is related to the sediment's adsorption/desorption capacity. Larger amounts of residue ((14)C) were released to the water columns at 5 degrees C than at 24 degrees C. Atrazine degraded in the shallow submerged anaerobic sediment's water columns over the 2-year period. Less than 2% (percent of applied in atrazine equivalent) of extractable atrazine and metabolites remained in the sediment after 2 years. The amount of nonextractable atrazine residue ((1)(4)C) was significantly higher in sediments at 24 degrees C than at 5 degrees C. In conclusion, atrazine accumulating in shallow undisturbed submerged sediments from nonpoint sources would most likely degrade and/or become nonextractable over time and would have a low probability of becoming a significant source to the water body. The conditions where accumulation and future release of atrazine have a greater potential to occur are under very cold temperatures with low adsorption capacity sediments.

Atrazine↗
PubMed1996

Two comparative endoscopic evaluations of Naprelan.

This paper describes the results of two endoscopic studies of Naprelan (Wyeth-Ayerst Laboratories, Philadelphia, Pennsylvania), a controlled-release formulation of naproxen sodium. In one study, 19 healthy male subjects received either 2 controlled release Naprelan 500-mg tablets once daily or 1 Naprosyn (naproxen; Syntex Laboratories, Inc., Palo Alto, California) 500-mg tablet BID. At baseline, all subjects had gastroduodenal endoscopy scores of 0 on both the Lanza and Euler scales. Although the trend favored Naprelan, differences in Lanza and Euler scale elevations were not statistically significant. Eight of 10 subjects in the Naprelan group and 7 of 9 subjects in the Naprosyn group reported a total of 27 adverse events (AEs). In the second study, healthy subjects received Naprelan 1,000 mg once daily, Naprosyn 500 mg BID, and film-coated aspirin 650 mg QID. In the stomach, there was a significant difference in favor of Naprelan over aspirin (P = 0.0001) and in favor of Naprosyn over aspirin (P = 0.0001). Fewer erosions were seen in the duodenum than in the stomach. In the duodenum, there was a significant difference in favor of Naprelan over Naprosyn (P = 0.0236), and in favor of Naprelan over aspirin (P = 0.0086), but the difference between Naprosyn and aspirin was not significant (P = 0.6643). Of the 23 subjects who received medication, 12 reported AEs: 8 while receiving aspirin, 3 while receiving Naprosyn, and 1 while receiving Naprelan. Differences in the number of erosions and ulcers seen following each of the periods of drug administration favored Naprelan and the Intestinal Protective Drug Absorption System.

Adolescent↗
PubMed1992

When is light work heavy? Components of the physical workload of sewing machine operators working at piecework rates.

Epidemiologists have associated the job of sewing machine operators with a high incidence of musculoskeletal and other health problems, despite its classifications as light work according to energy expenditure criteria. An ergonomic analysis was undertaken in a trouser factory in order to describe components of the physical load of this work: force exerted, repetitions, time allocation and postures. Work activity of ten operators was observed and timed in situ, and forces were measured with a dynamometer. The time required to sew one seam is very short, 10-15 s per trouser leg. This short cycle is repeated more than 1500 times during the work day, involving quasi-continuous movements of the same parts of the body. The fact that movements are repeated so many times means that small details of the task assume a great importance. During the work day, a substantial force is exerted, only part of which can be measured with current technology. By these measurements, operators lift an average 406.1 kg of trousers per day and exert an average total force of 2858.4 kg with the upper limbs and 24 267.9 kg with the lower limbs. The work posture is static: seated with upper back curved and head bent over the sewing machine. Movements of the upper limbs involve abduction and adduction of the shoulders while exerting a force. For the same task, there is considerable variation in the dimensions of workstations. Interviews were conducted to determine the types of musculoskeletal complaints. The components of work activity could be treated to these complaints and to existing epidemiological data on musculoskeletal problems among sewing machine operators. This type of detailed examination can be applied by health and safety personnel to identify task components which could be changed to minimize the probability of musculoskeletal problems.

Journal Article↗
PubMed1990

She ate not the bread of idleness: exhaustion is related to domestic and salaried working conditions among 539 Québec hospital workers.

Hospital workers completed a questionnaire on domestic and professional working conditions and health symptoms. Workers were asked to estimate the number of domestic work hours, and the degree of sharing of laundry, cleaning, meal preparation and childcare. Responses from the 532 women workers showed an average professional work week of 31.2 hours and an average domestic work week of 19.2 hours. The length of the domestic work week increased with the number of children, and the degree of sharing diminished. Among couples with children, the reported length of the domestic work week correlated highly with an index calculated from the degree of sharing of domestic tasks, and the number and ages of children. Exhaustion and insomnia were associated with work speed and shift work, respectively, at the hospital job, but also with the number of hours of domestic work. Backache, which was related to lifting weights in the workplace, was not associated with the number of reported hours of domestic work. Due to errors in formulating some questions, the study underestimates total hours of domestic work, and, probably, effects of domestic work on health. However, it is the first North American study to show the combined effects of domestic work and paid work on physical health symptoms among women.

Adult↗