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Biomedical subjects

P C Davidson

Publications and source records attributed to P C Davidson.

At least 19 recordsLinked to original sources
PubMed2001

What's ahead in glucose monitoring? New techniques hold promise for improved ease and accuracy.

Advances in blood glucose monitoring have made it easier, more comfortable, and more practical for patients to monitor frequently. The new meters for intermittent monitoring are smaller and less dependent on technical aptitude than older models. They require less blood, and many provide downloadable information for glucose analysis. Data systems used with new meters provide valuable information that can dramatically improve glycemic control. Continuous glucose sensing (figure 4) is another major breakthrough in management of diabetes. Current systems allow only retrospective analyses, but real-time readings should be available in the near future. Such technological advances hold promise for preventing both hypoglycemia and hyperglycemia and for reducing the risk of long-term complications associated with diabetes. An artificial, mechanical islet cell may be the big next step toward bringing this disease under control. By combining continuous glucose monitoring data with continuous insulin delivery via an external or an implantable insulin pump, the outlook promises to be much brighter for patients with type 1 diabetes.

Adult↗
PubMed1996

Reduction in severe hypoglycemia with long-term continuous subcutaneous insulin infusion in type I diabetes.

OBJECTIVE: To compare the incidence of severe hypoglycemia in patients crossed over from multiple daily injections (MDIs) of insulin to continuous subcutaneous insulin infusion (CSII). RESEARCH DESIGN AND METHODS: From a population of 225 patients using CSII, all patients who met the following selection criteria were included in the present study: 1) a minimum of 12 months on intensive therapy with MDIs before switching to CSII, and 2) a minimum of 12 months on CSII after crossover. Glycemic control and adverse event rates for the 1-year MDI control period were compared with those for the CSII therapy period. RESULTS: The incidence of severe hypoglycemia during MDI therapy declined from 138 to 22 events per 100 patient-years during the 1st year of CSII (P < 0.0001) and remained significantly lower in years 2, 3, and 4 on CSII (26, 39, and 36, respectively). HbA1c levels did not change significantly between the MDI phase and any year on CSII. However, in the subgroup of patients who had pre-CSII HbA1c levels of > or = 8.0%, the change to CSII was associated with a significant reduction in HbA1c from baseline to year 1 (8.9 +/- 0.8 vs. 8.1 +/- 1.0%, P = 0.0004). The difference in diabetic ketoacidosis rates between the MDI year (14.6 events per 100 patient-years) and the CSII period (7.2 events per 100 patient-years) was not statistically significant. CONCLUSIONS: CSII therapy was associated with a marked and sustained reduction in the rate of severe hypoglycemia without adversely affecting the level of glycemic control attained during MDI therapy. The more reproducible and flexible insulin delivery afforded by CSII was considered to be the major factor contributing to the improvement in severe hypoglycemia rates.

Adult↗
PubMed1995

Evaluation of the psychosocial impact of the MiniMed variable-rate implantable insulin pump.

We examined the psychosocial impact of treatment with an implantable insulin pump among persons with insulin-dependent diabetes mellitus (IDDM). Of specific interest was whether use of the MiniMed implantable insulin pump (MIP) resulted in changes in functional status, performance of diabetes self-care behavior, psychologic symptoms, and perceived level of stress. From a sample of 36 patients with IDDM, 10 persons were randomly selected to receive the MIP, while the remaining 26 served as control subjects. Additionally, a nonrandom sample of three MIP recipients from an additional site were included in the MIP group. At regular assessment intervals, all participants completed self-report questionnaires regarding psychosocial functioning and monitored blood glucose levels. After 4 months of MIP use, MIP recipients did not significantly differ from control subjects on any measure of psychosocial functioning; however, MIP use did have an impact on diabetes self-care. The MIP users monitored their blood glucose levels more frequently and had lower average blood glucose levels than control subjects. Additional follow-up is needed to determine the long-term psychosocial impact of implantable insulin pump therapy.

Adult↗
PubMed1994

Synthesis and transport of glutathione by cultured human retinal pigment epithelial cells.

PURPOSE: To characterize synthesis and transport of glutathione (GSH) by cultured human retinal pigment epithelial (RPE) cells. METHODS: Cultured human RPE cells were depleted of glutathione, then incubated with various concentrations of cysteine, glutamate, and glycine or with glutathione. High-performance liquid chromatography was used to measure intracellular glutathione with time. RESULTS: After depletion with diethylmaleate, intracellular glutathione was resynthesized from the amino acid precursors within 60 minutes. The addition of buthionine sulfoximine, a known inhibitor of GSH synthesis, completely eliminated the observed increase. Similar incubation with exogenous GSH failed to increase the intracellular GSH concentration. CONCLUSION: Cultured human RPE cells are able to rapidly synthesize glutathione from exogenously administered amino acids, but they are incapable of direct GSH uptake.

Adult↗
PubMed1993

Protection of retinal pigment epithelium from oxidative injury by glutathione and precursors.

PURPOSE: This study was performed to examine the effect of exogenous glutathione (GSH) or its precursor amino acids on oxidative injury in cultured human retinal pigment epithelium (RPE). METHODS: Cultured human RPE cells were suspended in Krebs-Henseleit medium, and 150 microM t-butylhydroperoxide was added. Cell viability was assessed by 0.2% trypan blue exclusion 30, 60, and 120 minutes after the addition of GSH or its amino acid precursors. RESULTS: Added GSH provided protection at concentrations of 0.01 mM and higher. The amino acid precursors for GSH, glutamate, cysteine, and glycine also protected against injury, but this required at least 0.1 mM of each amino acid. Inhibition of intracellular GSH synthesis by inclusion of 1 mM buthionine sulfoximine eliminated the protection by added amino acids but did not alter the protection by added GSH. CONCLUSIONS: These results indicate that protection by the amino acid precursors is mediated through synthesis of GSH, and they also show that exogenous GSH can provide protection against oxidative injury.

Amino Acids↗
PubMed1991

Management of posterior segment ocular trauma.

Ocular trauma is a leading cause of visual impairment in the United States. Despite advances in treatment, almost half the patients with posterior, penetrating ocular injuries have permanent, severe visual loss. There is controversy with regard to the optimal role and timing of vitrectomy in the management of posterior segment injuries, as well as the proper management of magnetic intraocular foreign bodies. Improvements in surgical instrumentation and technique, combined with an increased understanding of posterior segment pathobiology, continue to modify the indications for treatment. Each of these issues is discussed in light of recent contributions to the literature.

Eye Foreign Bodies↗
PubMed1984

Blood glucose discrimination training with insulin-dependent diabetics: a clinical note.

Two insulin-dependent diabetic adults were exposed to a blood glucose discrimination training program. Following baseline, during which subjects estimated their blood glucose levels twice daily, subjects received immediate feedback regarding the accuracy of their estimates. The procedure resulted in a large increase in accuracy of blood glucose level estimation. The implications of the findings were discussed.

Adult↗
PubMed1981

Exercise effects on fitness, lipids, glucose tolerance and insulin levels in young adults.

The effect of 3 different physical training programs on cardiorespiratory (cr) fitness, fasting plasma lipids, glucose and insulin levels, and scapular skinfold thickness was assessed in 64 healthy college men. Training sessions were held 4 times a week for 5 weeks. The cr fitness improved significantly and skinfold thickness decreased following the aerobic, the pulse workout (interval training), and the anaerobic training compared to the control group. Skinfold thickness, plasma insulin, and triglyceride concentrations were significantly intercorrelated before and after training. The exercise programs had no significant effect on plasma cholesterol, triglycerides, phospholipids, glucose tolerance, or insulin levels. Change in adipose mass was thus dissociated from change in plasma insulin and triglyceride concentrations. It was concluded that in young men plasma triglycerides, the lipid component mostly readily reduced by exercise, were too low to be reduced further by a physical training program.

Adolescent↗
PubMed1979

Effect of high- and low-fiber diets on plasma lipids and insulin.

Seven healthy young adults were maintained for two separate 1-week periods on each of two very high-carbohydrate diets, one with low-fiber and one with high-fiber content. In both diets 15% of the calories were from protein, 15% from fat, and 70% were from carbohydrate. The low-fiber diet consisted of milk, glucose, and dextrins in liquid formula form, the high-fiber diet was composed of starchy foods. The crude fiber content of the high- and low-fiber diets was 18.0 and 1.0 g, respectively. The diets were isocaloric and the subjects maintained a stable weight. During the low-fiber diet the fasting triglycerides rose, reaching a peak 45% above base-line in 6 days. During the high-fiber diet the triglycerides fell to a level slightly below base-line. The cholesterol fell 16 and 23% below base-line on the low- and high-fiber diets. The glucose response to test meals representative of each diet was similar. The insulin response to a low-fiber meal was twice as great as that to a high-fiber meal containing an equivalent amount of carbohydrate. The results suggest that carbohydrate-induced hyperlipemia does not occur if the high carbohydrate diet is rich in dietary fiber, and furthermore that the insulin-stimulating potential of foods in a very high-carbohydrate diet is a critical determinant of the magnitude of carbohydrate-induced lipemia.

Adult↗