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Biomedical subjects

L A Powell

Publications and source records attributed to L A Powell.

8 recordsLinked to original sources
PubMed2003

Interaction of glucose and long chain fatty acids (C18) on antioxidant defences and free radical damage in porcine vascular smooth muscle cells in vitro.

AIMS/HYPOTHESIS: Abnormalities of glucose and fatty acid metabolism in diabetes are believed to contribute to the development of oxidative stress and the long term vascular complications of the disease; therefore the interactions of glucose and long chain fatty acids on free radical damage and endogenous antioxidant defences were investigated in vascular smooth muscle cells. METHODS: Porcine vascular smooth muscle cells were cultured in 5 mmol/l or 25 mmol/l glucose for 10 days. Fatty acids, stearic acid (18:0), oleic acid (18:1), linoleic acid (18:2) and alpha-linolenic acid (18:3) were added with defatted bovine serum albumin as a carrier for the final three days. RESULTS: Glucose (25 mmol/l) alone caused oxidative stress in the cells as evidenced by free radical-mediated damage to DNA, lipids, and proteins. The addition of fatty acids (0.2 mmol/l) altered the profile of free radical damage; the response was J-shaped with respect to the degree of unsaturation of each acid, and oleic acid was associated with least damage. At a lower concentration alpha-linolenic acid (0.01 mmol/l) was markedly different in that, when added to 25 mmol/l glucose it resulted in a decrease in free radical damage to DNA, lipids and proteins. This was accompanied by a marked increase in antioxidant and glutathione concentrations as well as by increased gene expression is of gamma-glutamylcysteine synthetase, the rate-limiting enzyme in glutathione synthesis. CONCLUSIONS/INTERPRETATION: The results clearly show that glucose and fatty acids interact in the production of oxidative stress in vascular smooth muscle cells.

Animals↗
PubMed2001

Restoration of glutathione levels in vascular smooth muscle cells exposed to high glucose conditions.

Hyperglycemia-induced oxidative stress may play a key role in the pathogenesis of diabetic vascular disease. The purpose of this study was to determine the effects of glucose on levels of glutathione (a major intracellular antioxidant), the expression of gamma-glutamylcysteine synthetase (the rate-limiting enzyme in glutathione de novo synthesis), and DNA damage in human vascular smooth muscle cells in vitro. High glucose conditions and buthionine sulphoximine, an inhibitor of gamma-glutamylcysteine synthetase, reduced intracellular glutathione levels in vascular smooth muscle cells. This reduction was accompanied by a decrease in the mRNA expression of both subunits of gamma-glutamylcysteine synthetase as well as an increase in DNA damage. In high glucose conditions, incubation of the vascular smooth muscle cells with alpha-lipoic acid and L-cystine restored glutathione levels. We suggest that the decrease in GSH levels seen in high glucose conditions is mediated by the availability of cysteine (rate-limiting substrate in de novo glutathione synthesis) and the gene expression of the gamma-glutamylcysteine synthetase enzyme. Glutathione depletion is associated with an increase in DNA damage, which can be reduced when glutathione levels are restored.

Aorta↗
PubMed2001

Assessment of body composition change in a community-based weight management program.

OBJECTIVE: The purpose of this study was to validate the use of the leg-to-leg bioelectrical impedance analysis (BIA) system in assessing change in body composition over 32 weeks in overweight and obese women participating in a community weight management program. DESIGN: Intervention, with subjects prescribed an energy-restriction diet and exercise program for 32 weeks and body composition measured pre-study and after 12 and 32 weeks. SUBJECTS AND SETTING: Overweight and obese premenopausal women (n=201) with no overt disease were recruited at six sites into community-based weight loss programs. One hundred and twenty-four women completed all aspects of the study. INTERVENTION: Energy intake was set at 0.8 x resting metabolic rate (RMR) for weeks 1 through 12, 1.0 x RMR for weeks 13 through 20 and 1.2 x RMR for weeks 21 through 32. Energy intake was based on a food exchange table, with the number of food exchanges adjusted to encourage a percent distribution of 55% carbohydrate, 30% fat and 15% protein. Subjects increased their daily walking distance by 3.2 km above pre-study levels. MEASURES OF OUTCOME: Underwater weighing, seven skinfolds, and leg-to-leg BIA tests were used to assess body composition. RESULTS: A 3 x 3 repeated measures ANOVA revealed no significant difference in detecting change in FFM at 12 and 32 weeks among underwater weighing, BIA and skinfold, (F(4,492)=1.73, p=0.141) (decrease in FFM of 1.0+/-3.3 kg, 1.7+/-2.2 kg, and 1.4+/-3.3 kg respectively, 32 weeks). CONCLUSIONS: The leg-to-leg BIA system provides a valid measure of body composition change in overweight premenopausal women during a 32-week community-based weight loss program.

Adipose Tissue↗
PubMed1996

Resection of the right middle lobe and lingula for mycobacterial infection.

BACKGROUND: In a series of 229 patients infected with mycobacterial organisms, we noted a specific female phenotype that involves isolated infections of the middle lobe and lingula. METHODS: Thirteen patients were found to have infections of the middle lobe, lingula, or both. All of them were infected with Mycobacterium other then Mycobacterium tuberculosis, all were women, 12 of the 13 were slender, and most had variable combinations of skeletal abnormalities. All underwent resection of the middle lobe, lingula, or both. RESULTS: There were no operative deaths. Only 2 patients have had reactivation requiring additional antibiotic therapy. All patients have had a decreased number of pulmonary infections in the postoperative period. Anatomic findings at operation included a complete major fissure and at least a partially complete minor fissure with middle lobe resections or an elongated lingula. CONCLUSIONS: Mycobacterial infection of the middle lobe and lingula is primarily a disease of asthenic women and is often associated with skeletal abnormalities and complete fissures or an elongated lingula. We recommend that surgical intervention be performed early once the condition is identified.

Aged↗
PubMed1993

Simultaneous maxillary and mandibular reconstruction with one free osteocutaneous flap.

The concept of immediate reconstruction of massive facial injury with rigid internal fixation and free-tissue transfer continues to evolve. This case is unique in that it is the first report of the following: (1) simultaneous combined maxillary and mandibular reconstruction with one vascularized bone graft and (2) immediate total maxillary reconstruction with vascularized fibular bone. The nasopharynx was closed with a tubed radial forearm flap. Reconstruction was staged over several days, with dissection/banking of flaps, grafts, recipient sites, and debridement as a preliminary stage.

Adult↗
PubMed1992

Killing of Legionella pneumophila by nitric oxide in gamma-interferon-activated macrophages.

The role of nitric oxide (NO) radicals in killing the intracellular bacterial pathogen Legionella pneumophila (Lp) was examined in infected macrophages. Murine (RAW 264.7) and human (HL-60) cell monolayers were treated with 100 U/ml gamma-interferon (IFN) and cocultured with Lp in the presence and absence of NGMMA, a specific inhibitor of NO production. Viable Lp in IFN-treated RAW 264.7 cells decreased from 3.8 to 0.7 +/- 0.12 log CFU/ml after 24 h incubation, whereas in IFN+NGMMA-treated RAW 264.7 cells, viable Lp persisted at 2.2 +/- 0.2 log CFU/ml after 24 h. This increased survival corresponded with an inhibition of NO production (5.65 +/- 2.99 microM with NGMMA vs. 58.6 +/- 5.36 microM without NGMMA). Viable Lp were susceptible to killing, in a dose-dependent fashion, by 0, 2.5, and 5.0 mM sodium nitroprusside, a source of NO radicals. IFN-treated RAW 264.7 cells also had significantly decreased levels of intracellular iron (below assay limit) when compared to IFN+NGMMA-treated cells (72.0 +/- 0.78% of control). Normally permissive HL-60 cells treated with IFN were bacteriostatic rather than bactericidal, and NO production was not detected above background. Thus, NO radicals play a critical role in the bactericidal activity against Lp by IFN-treated RAW 264.7 cells, but the absence of NO production limits IFN-treated HL-60 cells to bacteriostasis.

Animals↗
PubMed1985

The Reagan-era shift toward restrictiveness in old age policy in historical perspective.

For forty years following the passage of the Social Security Act, the United States experienced a liberalization in public policy toward the aged. In the late 1970's, the momentum of this liberalization began to ebb, and by the early 1980's, a shift toward greater restrictiveness was underway. Scholars and journalists often discuss this Reagan-era shift as if it were a unique policy initiative. A case can be made, however, that this is just a recent example of a recurrent pattern of social policy reform and reaction in the history of American politics. This point is illustrated by placing the current policy shift alongside a historically remote period.

Aged↗