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Biomedical subjects

E D Lehmann

Publications and source records attributed to E D Lehmann.

At least 19 recordsLinked to original sources
PubMed1996

Computer assisted diabetes care: a 6-year retrospective.

Over the past 6 years we have designed a number of computer-based prototypes for the provision of therapeutic advice and the generation of glycaemic predictions in insulin-dependent (type 1) diabetic patients. In this paper we provide an overview of some of this work, and describe our experiences in trying to develop such methods for clinical use. We review, as an example, a model of the glucoregulatory system which has been developed for patient and medical staff education about type 1 diabetes mellitus, as well as possibly for therapeutic use. Using individualised parameter values the predictions of the model can be applied to generate 24-h simulations of patient blood glucose profiles. Previous preliminary retrospective validation work performed with this model has revealed a mean predictive accuracy for blood glucose simulations of approximately 2 mmol/l. Conceptual limitations of such modelling approaches are considered. We comment that such "mechanistic' models may lack the necessary sophistication and flexibility to represent the complexity of the human glucoregulatory system and the challenges it has to face. Although such methodologies may therefore not be suitable for safe and effective application in routine clinical practice, we conclude that the evolution of such a system for demonstration/educational purposes could have widespread clinical utility as an interactive teaching tool.

Artificial Intelligence↗
PubMed1996

Ethnicity affects IGFBP-3 and IGF-II in normal healthy young adult subjects.

OBJECTIVE: While the effects of age on the growth hormone/insulin-like growth factor (IGF) axis are well documented, the influence of ethnic background is unknown. The differences in IGF and IGF binding proteins (IGFBPs) were investigated in two ethnic groups. DESIGN: A cross-sectional study of an age-selected cohort of healthy, normoglycaemic, non-obese Caucasian (C) and Asian (A) subjects. PATIENTS: Fifty-three (27 C, 26 A) subjects with a mean age (+/- SD) of 20.6 +/- 0.8 years were studied. MEASUREMENTS: Fasting measurements of glucose, insulin, IGF-I, IGF-II, IGFBP-1 and IGFBP-3. Western ligand blotting and immunoblotting with IGFBP-2 and IGFBP-3 of serum samples. RESULTS: There were no significant differences in IGF-I levels between Caucasian and Asian subjects (C 218 +/- 55 vs A 229 +/- 40 micrograms/l; P = 0.44). IGF-II (C 707 +/- 110 vs A 583 +/- 75 micrograms/l; P < 0.0001) and IGFBP-3 (C 5.9 +/- 1.2 vs A 5.12 +/- 1.17 mg/l; P = 0.01) levels were significantly higher in Caucasian subjects. Immunoblotting of ligand blots revealed no protease activity on either IGFBP-3 or IGFBP-2 to account for these ethnic differences. CONCLUSIONS: Ethnic differences in IGFBP-3 and associated IGF-II levels may affect the inter-relationships of IGFs and their binding proteins and need to be considered when interpreting IGF data on growth and metabolism.

Adult↗
PubMed1996

A family history of NIDDM is associated with decreased aortic distensibility in normal healthy young adult subjects.

OBJECTIVE: NIDDM is associated with stiffer arteries and an increased incidence of macrovascular disease. NIDDM has strong familial inheritance. We studied the associations of a family history of NIDDM with blood pressure-corrected aortic distensibility (Cp). RESEARCH DESIGN AND METHODS: Because age is a strong determinant of arterial distensibility, we studied an age-select cohort of 67 healthy normotensive normoglycemic young adults along with fasting measurements of glucose and insulin concentrations. Cp was calculated from noninvasive Doppler ultrasound measurements of pulse wave velocity along the descending thoracoabdominal aorta. RESULTS: The mean age of the subjects was 20.6 +/- 0.7 (mean +/- SD) years. A total of 22 subjects gave a positive family history of NIDDM in a parent or grandparent. Subjects with a positive family history of NIDDM had significantly less distensible (i.e., stiffer) aortas than their age- and sex-matched counterparts who gave no family history of NIDDM (Cp [dimensionless]: 0.22 +/- 0.04 vs. 0.25 +/- 0.04, P = 0.02). Subjects with a positive family history of NIDDM also had significantly higher fasting glucose (5.1 +/- 0.4 vs. 4.9 +/- 0.4 mmol/l, P = 0.009) and insulin (7.5 +/- 5.5 vs. 4.2 +/- 2.0 mU/l, P = 0.02) levels and BMIs (23.2 +/- 2.3 vs 21.1 +/- 2.5 kg/m2, P = 0.002). On multivariate regression analysis, family history of NIDDM (P = 0.03) was the only significant independent predictor of Cp. CONCLUSIONS: A positive family history of NIDDM is associated with decreased aortic distensibility in early adult life. The relevance of these observations to future cardiovascular events merits further investigation.

Adult↗
PubMed1995

Aortic distensibility in patients with cerebrovascular disease.

1. Non-invasive aortic compliance measurements have been used previously to assess the distensibility of the aorta in several pathological conditions associated with increased cardiovascular risk. We set out to establish whether aortic compliance is abnormal in patients with stroke. 2. Pulse wave velocity measurements of thoraco-abdominal aortic compliance were made in 20 stroke patients and 25 age- and sex-matched hospitalized, non-stroke control subjects putatively free of cardiovascular disease. Since compliance varies with non-chronic changes in blood pressure, a blood pressure corrected index of aortic distensibility, Cp, was calculated. 3. Aortic compliance was significantly reduced in patients with stroke compared with non-stroke control subjects (0.46 +/- 0.27 versus 0.86 +/- 0.34%/10 mmHg, P < 0.0002), corresponding with higher values for pulse wave velocity. Stroke patients also had significantly higher systolic and diastolic blood pressures (P < 0.02 and P < 0.002 respectively) and total cholesterol levels (P < 0.004) than the control subjects. Calculation of Cp did not alter the observation of stiffer aortas in the stroke cohort (P < 0.0007). 4. In both stroke patient and control cohorts, as expected, inverse trends were observed between aortic compliance and blood pressure. Also as expected, in the control group Cp values did not show a relationship with blood pressure (r = 0.02, P = 0.092, not significant). However, in the stroke cohort a marked dependence of Cp on blood pressure was observed (r = -0.48, P = 0.03). 5. Transoesophageal echocardiographic studies have recently identified advanced atherosclerosis in the ascending aorta as a possible source of cerebral emboli and an independent risk factor for ischaemic stroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗