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Biomedical subjects

K N Frayn

Publications and source records attributed to K N Frayn.

At least 181 records · Page 10Linked to original sources
PubMed1986

Plasma catecholamines in the acute phase of the response to myocardial infarction.

Plasma catecholamine (adrenaline, noradrenaline and dopamine) concentrations have been measured in 48 patients within 6 hours of the onset of symptoms of an acute myocardial infarction. The concentrations of all three catecholamines were elevated, and there were positive correlations between plasma noradrenaline concentrations and the severity of infarct as assessed by the coronary prognostic index and serum LDH levels. Plasma glucose, free fatty acid, lactate and cortisol levels were elevated while insulin levels were reduced. The site of infarction did not influence the pattern of hormonal and metabolic responses although heart rate was significantly lower in the inferior than in the anterior infarct group. Seven patients went into ventricular fibrillation shortly (less than 1.8 h) after blood sampling. Plasma catecholamine concentrations were markedly elevated in these patients with levels similar to those previously reported after cardiac arrest.

Adult↗
PubMed1985

Plasma catecholamines in patients with acute myocardial infarction and in cardiac arrest.

Plasma catecholamine concentrations in cardiac arrest (ventricular fibrillation and asystole) are significantly higher than after myocardial infarction. The levels reached are well above those normally required to stimulate cardiac activity. Possible reasons for the failure of the myocardium to respond to the catecholamines are discussed and the rationale for giving more catecholamines is questioned.

Adult↗
PubMed1985

The relationship of plasma catecholamines to acute metabolic and hormonal responses to injury in man.

Plasma catecholamine concentrations in 40 patients shortly after accidental injury rose progressively with increasing severity of injury. Norepinephrine and epinephrine concentrations were unrelated other than by a common rise with severity; dopamine was closely related norepinephrine and not independently related to injury severity. Plasma glucose concentrations rose after injury; however, this was related only to the plasma epinephrine concentration and not independently to injury severity. Plasma lactate concentrations, in contrast, showed components related both to severity of injury and independently to norepinephrine and epinephrine concentrations. Plasma insulin concentrations were uniformly low, especially with respect to the hyperglycemia, in patients with high plasma epinephrine concentrations. Plasma concentrations of free fatty acids and of cortisol were unrelated to plasma catecholamine concentrations, as were pulse rate and blood pressure. These relationships confirm the expected role of the sympathoadrenal system in the metabolic changes following injury in man.

Adolescent↗
PubMed1984

Metabolic control in non-septic patients with musculoskeletal injuries.

Changes in gaseous exchange, plasma substrates and hormones and excretion of nitrogen were followed in 13 non-septic male patients, all of whom had sustained at least 1 fracture of a long bone. Results were compared with normal subjects given glucose to produce a range of substrate and hormone concentrations. Over the 3 weeks following injury, oxidation of fat decreased from high levels whilst oxidation of carbohydrate rose. This reflected to some extent changes in availability of substrate, but early after injury oxidation of fat was higher than expected for the concentration of free fatty acids in plasma and later oxidation of carbohydrate was increased relative to concentrations of glucose and insulin. Concentrations of insulin in plasma were high for the prevailing concentrations of glucose, and peak urinary excretion of nitrogen coincided with maximum levels of insulin. It was concluded that in the injured patient there are changes at the level of utilization and oxidation of plasma substrates as well as in their availability, and that there is marked unresponsiveness of protein metabolism to the normal anabolic effect of insulin.

Adolescent↗
PubMed1984

Plasma somatomedin activity after injury in man and its relationship to other hormonal and metabolic changes.

Plasma somatomedin activity was measured in 12 patients who had sustained non-fatal musculo-skeletal injuries. It was depressed for 2-3 d after injury, but this depression bore no relationship to the catabolic response to injury which, as judged by urinary nitrogen excretion, was maximal at about one week. The depression of somatomedin activity may have been related to the high plasma cortisol concentrations observed during the first few days after injury. Plasma growth hormone concentrations were high acutely after injury but rapidly returned to normal. The changes in plasma somatomedin activity were thus unrelated to those in growth hormone, but were very similar to those in plasma insulin concentrations. A marked positive relationship was observed between plasma insulin concentrations and urinary nitrogen excretion, indicating unresponsiveness of protein metabolism to the normal anabolic effects of insulin. The study showed, however, that this was not as a result of low somatomedin activity.

Adolescent↗
PubMed1983

The effect of sepsis on the oxidation of carbohydrate and fat.

Oxidative metabolism has been studied by indirect calorimetry in 27 patients with sepsis and in 7 non-septic patients while they were all receiving total parenteral nutrition. Glucose oxidation was reduced in the septic patients and fat oxidation continued despite the infusion of an excess of glucose. The extent of these changes depended on the severity of the septic state as measured by the scoring system described in the preceding paper. The mechanism of these changes is not known. They were not related to an elevation of the plasma nonesterified fatty acid concentration. Alterations must have occurred in the way fat was taken up and metabolized by the cells. Here insulin resistance and the highly significant positive relationship found between the plasma cortisol concentration and the sepsis score might be important.

Adult↗
PubMed1983

Persistence of high plasma glucose, insulin and cortisol concentrations in elderly patients with proximal femoral fractures.

Plasma glucose, insulin and cortisol concentrations were measured in elderly patients with femoral neck fractures. The results have been compared with those in younger injured patients as well as younger and elderly control subjects. There was a prolonged elevation of plasma glucose, insulin and cortisol concentrations after femoral neck fractures, in contrast to a rapid return to normal in younger injured patients. Comparison with the control groups suggested that this might reflect the effects of immobility rather than of age or of injury per se. The pattern of insulin resistance together with a high cortisol concentration could hinder recovery.

Adolescent↗
PubMed1983

Fat metabolism in elderly patients with severe hypothermia.

Elderly patients with accidental hypothermia (core temperatures 25.0-35.5 degrees C) have been studied to determine the effect of low temperature on energy metabolism. The respiratory exchange ratios were low (median 0.75). Concentrations of plasma glycerol, non-esterified fatty acids and ketone bodies were high, and, except in the case of glycerol, rose with the duration of the hypothermia. Plasma glucose concentrations were often high but extremely variable. Arteriovenous differences across the forearm showed net release of glycerol and extraction of ketone bodies. Despite the hypothermia the mean extraction ratios for acetoacetate and 3-hydroxybutyrate were very similar to published values in normal, fasting, euthermic subjects. It was concluded that, in agreement with other work showing inhibition of glucose utilization at low temperature, fat is the main fuel used at very low body temperatures.

3-Hydroxybutyric Acid↗
PubMed1983

Calculation of substrate oxidation rates in vivo from gaseous exchange.

This paper reviews the assumptions involved in calculating rates of carbohydrate and fat oxidation from measurements of O2 consumption, CO2 production, and urinary nitrogen excretion. It is shown that erroneous results are obtained in the presence of metabolic processes such as lipogenesis and gluconeogenesis. The apparent rates calculated under these conditions can, however, be interpreted as net rates of "utilization." Thus the apparent rate of carbohydrate oxidation is the sum of the rates of utilization for oxidation and for lipogenesis minus the rate at which carbohydrate is formed from amino acids. The apparent rate of fat oxidation is the difference between the rates of oxidation and synthesis from carbohydrate, so that the apparently negative rates encountered in patients infused with glucose do quantitatively represent net rates of synthesis. Other processes such as synthesis of ketone bodies or lactate at rates greater than their utilization can also disturb the calculations, but the magnitude of the effect can be estimated from appropriate measurements. Methods of correcting the observed gaseous exchange in these circumstances are given.

Gluconeogenesis↗
PubMed1983

Sample preparation with ion-exchange resin before liquid-chromatographic determination of plasma catecholamines.

Estimation of plasma catecholamine concentrations by "high-performance" liquid chromatography, although increasingly used, still presents difficulties. We describe a method for clean-up of plasma samples on cation-exchange resin before they are extracted with alumina. This procedure eliminates many of the interfering compounds often present in plasma extracts prepared with the alumina treatment alone. The method can be adapted to use commercially available disposable cation-exchange columns.

Catecholamines↗
PubMed1981

Effects of diabetes and of injury on muscle protein in the mouse, and their interaction.

The effects of a 20% dorsal scald injury and of different severities of streptozotocin diabetes on hindquarter muscle protein have been studied in the mouse. Ten days after scald injury muscle protein contents were generally unaffected, whereas moderate diabetes (200 mg streptozotocin/kg body weight; plasma glucose concentrations 17--46 mmol/1; normal 11 mmol/l) led to net loss of muscle protein. Production of scald injury in the moderately diabetic mouse caused significant additional loss of muscle protein, especially from the extensor digitorum longus Milder diabetes (maximum plasma glucose concentration 15 mmol/l) did not lead to loss of muscle protein. However, scald injury in the mildly diabetic mouse caused significant loss of protein from all muscles studied. The effects of diabetes and of injury on loss of muscle protein were at least additive and in some muscles probably synergistic.

Animals↗
PubMed1981

Substrate oxidation shortly after accidental injury in man.

1. Oxidative metabolism have been studied by indirect calorimetry in 42 patients within the first 6 h after accidental injury. 2. The level of energy expenditure bore no relationship to the severity of the injury and varied more widely from patient to patient than in normal subjects. 3. After minor and moderate injuries the respiratory exchange ratio (mean 0 . 86) was not different from that in normal subjects on a mixed diet. After severe injuries the ratio (mean 0 . 78) was significantly lower (P less than 0 . 005), indicating that the main substrate for oxidation in these patients was fat, despite their hyperglycaemia.

Adolescent↗
PubMed1980

Metabolic aspects of hypothermia in the elderly.

1. Plasma concentrations of glucose, lactate, amino acids, non-esterified fatty acids, glycerol, ketone bodies, insulin and cortisol were measured in 43 elderly patients with hypothermia. In 15 of these patients forearm arteriovenous differences were also measured. Core temperatures ranged from 25.9 to 35.5 degrees C. 2. The metabolic state was of mobilization of glycogen and triacylglycerol stores, with high plasma concentrations of lactate and lipid metabolites. The plasma concentration of glucose was raised in those with hypothermia of a short duration (less than 6 h). In other patients it was low in those with core temperatures around 30 degrees C, but below this temperature it was variable and often high. Concentrations of other metabolites or hormones were not related to core temperature. 3. Plasma concentrations of cortisol were high and positively correlated with those of lactate and glycerol, suggesting active involvement in stimulation of muscle glycogenolysis and of lipolysis. 4. Plasma concentrations of insulin ranged from very low to very high and appeared to depend on the concentrations of both glucose and alanine. 5. Arteriovenous differences were generally small. There was peripheral release of lactate and of amino acids but no overall peripheral uptake of glucose. In nine out of 15 patients there was a significant peripheral release of glucose.

Aged↗