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Biomedical subjects

E R Carson

Publications and source records attributed to E R Carson.

At least 37 records · Page 2Linked to original sources
PubMed1990

The decision-making process in child language assessment.

The task of assessing a child's language for the purpose of intervention requires the ability to interpret information from a variety of sources. Knowing how that information is to be used during therapy plays an important part in deciding what type of information needs to be collected and how it will be interpreted. There needs to be a plan that will assist the speech therapist in analysing and interpreting most of the data that would be needed when making therapy-related diagnostic statements. A systems approach offers concepts and methods for devising a plan which will outline the necessary decisions. The purpose of this paper is to present, in a flow chart, the questions that need to be asked in the process of assessing a child's language development for the purpose of intervention; to indicate the type of information that would be needed to answer the questions; to state how the information would be interpreted; to suggest the type of tools that would be needed to collect this information; and to outline how the information can be presented so that a greater quantity of data can be summarised and interpreted in a systematic manner.

Child↗
PubMed1989

ANABEL: intelligent blood-gas analysis in the intensive care unit.

ANABEL (ANalysis of Acid-Base status by Evaluating Lisp) is a prototype medical intelligent decision-support system aiming to assist clinicians in an Intensive Care Unit environment with the interpretation of blood-gas measurements. Its architecture is based on the merging of representations for declarative (domain-descriptive) and procedural (problem-solving) medical knowledge. The system performs diagnosis in two stages (tentative and differential) by first evaluating elementary computational units of procedural knowledge (procedures) and then abstracting their symbolic outputs in generating text. Thus, a 'semantic trace' is built which reflects the system's line of reasoning in reaching its conclusion. This paper describes the design aspects, development and clinical validation of ANABEL.

Acid-Base Imbalance↗
PubMed1989

The principles and prototyping of a knowledge-based diabetes management system.

This paper describes the principles and prototyping of a computer-based system being developed to assist in the management of diabetes mellitus. Unlike other approaches based upon mathematical modelling or the use of computer algorithms, this system adopts one derived from artificial intelligence, seeking to incorporate the dynamics of glucose and insulin in a manner which reflects their clinical importance. The resultant logical model (qualitative algebra) defines the relationships between changes in insulin dose and site and time of injection and glycaemic response. In this manner the computer-based system, implemented in Prolog, can be used to provide advice concerning insulin therapy by means of making qualitative predictions of patient outcome of blood glucose profile resulting from alternative insulin regimens.

Blood Glucose↗
PubMed1986

The effect of metabolic control on leucine metabolism in type 1 (insulin-dependent) diabetic patients.

Leucine production rate, metabolic clearance rate and oxidation rate were measured in 10 Type 1 (insulin-dependent) diabetic patients after 24 h insulin withdrawal, conventional insulin therapy and an overnight insulin infusion to maintain normoglycaemia, and in 10 control subjects. In the insulin-withdrawn patients, leucine concentration (259 +/- 17 mumol/l), production rate (2.65 +/- 0.29 mumol . min-1 . kg-1) and oxidation rate (0.69 +/- 0.10 mumol . min-1 . kg-1) were significantly greater (p less than 0.001; p less than 0.05; p less than 0.005 respectively) than corresponding values in control subjects (127 +/- 6; 1.81 +/- 0.12; 0.19 +/- 0.02). Following conventional insulin therapy, leucine concentration (162 +/- 12 mumol/l) and oxidation rate (0.43 +/- 0.05 mumol . min-1 . kg-1) were lower than after insulin withdrawal but were still significantly greater than in control subjects (p less than 0.05; p less than 0.005). Although leucine concentration, production rate and metabolic clearance rate were normal after an overnight insulin infusion, leucine oxidation rate was still greater than normal (0.34 +/- 0.06 mumol . min-1 . kg-1; p less than 0.05). These results suggest that increased leucine concentration in insulin deficiency is due to elevated leucine production rate caused by increased proteolysis, and that leucine concentration is restored to normal by insulin treatment.

Adolescent↗
PubMed1984

Number and affinity of insulin receptors in intact human subjects.

A simple model of the distribution and metabolism of insulin in vivo has been evaluated using data from insulin infusion into a group of normal subjects. The major rate-limiting step for access to degradation pathways is assumed to consist of binding of the ligand to a single population of insulin receptor sites, except that provision is made for the possibility of linear non-receptor-mediated degradation and for the phenomenon of negative cooperativity. The model has been shown to accommodate the non-linearity of insulin metabolism, allows, evaluation of receptor association and dissociation constants and provides for the first time an estimate of total accessible receptor number in the intact organism. For normal fasting man the model predicts 1.00 +/- 0.05 nmol accessible binding sites/kg (mean +/- SD).

Humans↗
PubMed1984

Validation of simple and complex models in physiology and medicine.

The problem of assessing the value of mathematical models in physiology and medicine is considered. The role of validation within the modeling process is clearly defined. An appropriate vocabulary and validation procedures to be adopted are outlined for simple and complex models, with these two classes defined operationally on the basis of theoretical identifiability. Some examples illustrating these validation procedures are briefly discussed. It is shown that simple and complex models each have a role both in physiology and clinical application when properly validated.

Animals↗
PubMed1981

Modeling and identification of metabolic systems.

Introductory principles of physiological systems analysis by computer simulation or computation are introduced. The problems of model formulation, identification, and validation are examined. Selected guidelines for successful modeling are suggested, and examples of such applications in the field of endocrinology and metabolism are given.

Animals↗
PubMed1978

Anabolic role of urea in renal failure.

The amount of urea nitrogen released and the amount reincorporated into albumin has been measured in healthy and uremic individuals on both normal and low-protein diets. The albumin synthesis rate was measured simultaneously. Gut urea breakdown was only 50% higher in renal failure than in health, but the efficiency of utilization of the nitrogen thus released was increased more than 6-fold in renal failure and was higher on a low protein than on a normal protein diet. The lower the albumin synthetic rate, the greater was the efficiency of incorporation of urea nitrogen into albumin. The rate of urea nitrogen incorporation into albumin increased on average 14-fold in chronic renal failure. The absolute rate of utilization (84 mumole/hr) was, however, small and comprised on average only 2.4% of the nitrogen used in albumin synthesis. These findings suggest that although some urea derived nitrogen is incorporated into albumin, the amount is not nutritionally significant even under conditions of protein deprivation and high urea availability.

Albumins↗
PubMed1977

Studies on the kinetics of unconjugated [14C]bilirubin metabolism in normal subjects and patients with compensated cirrhosis.

1. The kinetics of unconjugated [14C]-bilirubin metabolism have been investigated and analysed in terms of a three-pool model in a group of seven normal subjects and in a group of eight cirrhotic patients who had appreciable impairment of liver cell function. 2. In the patients with cirrhosis, the plasma unconjugated bilirubin was either normal or only slightly increased but the metabolism of unconjugated bilirubin was deranged. 3. The mean volume of distribution, the mean 4 h retention, and the mean mass of the rapidly mixing pool were all significantly greater than in the normal subjects. In contrast, mean fractional clearance rate and mean estimated erythrocyte life-span were significantly less than in the normal subjects. 4. The mean functional transfer rates and fluxes from pool 1 (rapidly mixing pool--'plasma') to pool 3 ('extravascular') and vice versa were significantly greater than the corresponding values in the normal subjects. 5. The results indicate that, in patients with compensated cirrhosis, the efficiency of the liver in extracting unconjugated bilirubin from plasma against a concentration gradient is impaired, even though the liver's capacity to conjugate bilirubin may be normal. As a consequence of the increased volume of distribution, the absolute hepatic clearance of unconjugated bilirubin is relatively well maintained.

Bilirubin↗
PubMed1976

A systems model of blood glucose control.

A mathematical model for the short-term control of glucose is presented, focusing upon the role of the liver. Non-linear representation is provided, enabling complete system behaviour of the metabolic and endocrine processes to be analysed, including both basic auto-regulation and higher levels of control. The level of a priori knowledge incorporated in the formulation is maximised by including unit process dynamics, making direct use of known enzymological data. From simulation results, hypotheses concerning system structure are tested. Hormones are seen to be important in maintaining the biochemical environment, providing the coarse control. The dominant control of flux within the glucose metabolic pathways is intrinsic to the enzyme systems which can be looked upon as providing the fine tuning and auto regulatory effects.

Blood Glucose↗