Muscle adenosine 5'-triphosphate and creatine phosphate concentrations in relation to nutritional status and sepsis in man.

1. Intramuscular concentrations of adenosine 5'-triphosphate (ATP) and creatine phosphate were measured in the vastus lateralis muscle of 28 non-septic malnourished patients and 31 septic malnourished patients. Similar measurements were made on the rectus abdominis muscle of about one-third of these patients. All results were compared with those obtained from 15 normally nourished non-septic control subjects. 2. Objective measurements of nutritional status (both anthropometric and biochemical) and sepsis were recorded in all subjects. 3. The vastus lateralis muscle of the non-septic and septic malnourished patients had intramuscular concentrations of ATP and total adenine nucleotides (TAN) that were up to 30% lower than control values, depending on the reference base used. 4. In the rectus abdominis muscle, ATP and TAN concentrations were up to 60% lower than control values, and creatine phosphate up to 47% lower, again depending on the reference base used. 5. In both muscles, the changes were more marked in those patients who were septic as well as malnourished.

Hormonal and metabolic responses to glucose infusion in sepsis studied by the hyperglycemic glucose clamp technique.

Although nutritional support is vital to treatment of severe sepsis, the septic patient does not respond normally to glucose infusion. We have used the hyperglycemic glucose clamp technique to investigate the initial hormonal and metabolic responses of the septic patient to glucose under controlled conditions. The plasma glucose concentration was raised to and maintained at 12 mmol/liter for 2 hr in 12 septic patients and 11 normal controls. Glucose utilization, assessed from the amount infused, was significantly depressed in the patients, despite similar plasma insulin concentrations in the two groups. Forearm glucose uptake was similarly impaired. Despite very similar plasma free fatty acid concentrations in the two groups, which were suppressed equally by the glucose infusion, whole-body fat oxidation was elevated in the patients compared with the controls, and suppressed to a lesser extent in response to glucose. Glycerol and ketone body concentrations were elevated in the patients in keeping with a picture of accelerated release, clearance, and oxidation of fatty acids. Plasma cortisol, epinephrine, and norepinephrine concentrations were elevated in the septic patients in a severity-related manner, but not to high levels compared with experimental work. Norepinephrine showed no response to the glucose infusion in either group. Plasma glucagon concentrations were not significantly elevated in the septic patients. We conclude that the hyperglycemic glucose clamp provides a useful model for studying glucose intolerance in sepsis. Impaired glucose utilization in septic patients is associated with increased fat oxidation, although the hormonal basis for these changes is still unclear.

Post-traumatic creatinuria.

The creatinuria after musculoskeletal injuries was studied in 31 patients. In addition to creatine the urinary outputs of creatinine, total nitrogen, and 3-methylhistidine were studied. Plasma creatine, creatinine, and guanidinoacetate concentrations were measured in some patients. In rats the effect of bilateral hind-limb ischemia was observed on the urine outputs of creatine and creatinine, and on the creatine, protein, and DNA contents of the hind limbs and carcass. In man the creatinuria was positively related to the severity of the injury and this relationship was stronger than with the urinary output of either creatinine or total nitrogen. In the rat creatinuria was related to the duration of the limb ischemia. The mechanism of the creatinuria is not known but the experiments on rats showed part of the excess creatine to be derived from the damaged muscle and excreted shortly after the injury, and part from the undamaged muscle of the carcass which provided the delayed excretion. It is suggested that creatinuria could be used as an indicator of the post-traumatic 'flow' phase.

Intracellular free amino acids in undernourished patients with or without sepsis.

1. Thigh muscle samples for analysis were obtained from 35 control subjects and 12 severely ill patients, of whom five had disease-induced undernutrition and seven had associated sepsis. An improvement in the Bergström technique for analysing muscle needle biopsy samples was used. 2. Muscle water, chloride and DNA were increased in both groups of ill patients, indicating an increase in the extracellular component and loss of muscle protein. 3. Falls in the concentrations of glutamine, glutamate, arginine, histidine, ornithine and lysine and rises in those of glycine, serine, asparagine, tyrosine, valine, leucine, isoleucine, phenylalanine, methionine and tryptophan were observed in the group of ill patients compared with those in the control subjects. The changes were present mainly in the patients with sepsis, significant differences between these and the undernourished ones without associated sepsis being observed in glutamine, lysine, tyrosine, valine, leucine, isoleucine, phenylalanine and methionine. The changes were either absent or slight in plasma. 4. The increased concentrations observed in six essential amino acids in the septic patients, but not in those with undernutrition, is consistent with the increased catabolic rate of sepsis. 5. However, the branched-chain amino acids, and lysine, threonine, arginine, and histidine, were present in lower concentrations than might be expected from catabolism, presumably due to utilization. It is suggested therefore that septic patients might benefit from increased proportions of these amino acids in their feeding regimen.

Patterns in the excretion of muscle markers after trauma and orthopedic surgery.

The urinary output of 3-methylhistidine (3-MeHis), creatinine, creatine, and zinc has been followed in 13 patients after accidental injuries and in nine patients undergoing elective orthopedic operations. The accidental injuries were classified by their Injury Severity Score (ISS) and according to the amount of muscle damage by the method of Grant and Reeve (15). The latter method gave two groups, (I) "very severe," and (II) "severe." The changes in the urine were not related to ISS. The initial output of 3-MeHis and zinc was greater in Group I than in Group II or in patients after total hip replacement, in whom muscle damage was least. The pattern of excretion of the excess 3-MeHis in Group I and after hip replacement suggested that it was derived from the breakdown of muscle injured in the accident or operation. Only in Group II and after total knee replacement were there additional changes which could be attributed to a generalized increase in muscle breakdown, said to be typical of the post-traumatic "flow" phase, e.g., the simultaneous increase in the output of all four muscle markers, to a peak about 6 days after the injury. In these patients the relative importance of muscle at the injury site and elsewhere is not clear. The most constant changes after accidental or operative trauma were delayed increased in the excretion of creatine and zinc. These changes, and the abnormality of the 3-MeHis/creatinine ratio, showed that alterations in muscle metabolism could persist for long periods after trauma.

Protein metabolism after unilateral femoral fracture in the rat, and comparison with sham operation.

Urinary excretion of nitrogen, creatinine and N tau-methylhistidine were measured in the rat after unilateral femoral fracture or sham operation. Increased urinary nitrogen excretion occurred in both groups of rats. Cumulative excretion of both nitrogen and N tau-methylhistidine was slightly greater after femoral fracture than after sham operation and this difference agreed quantitatively with loss of muscle protein from the limb with fracture. Sham operation caused no local effect on muscle-protein content and no differences were seen in muscle-protein content between the uninjured hind limb of rats with femoral fracture and either hind limb of sham-operated rats. It was concluded that bone fracture per se does not contribute significantly to the increased urinary nitrogen excretion seen after femoral fracture in the rat; similar changes are produced by equivalent sham operation and any difference between the effects of the two procedures represents local muscle wasting, probably due to disue of the fractured leg.

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.

Compartmentation between glycolysis and gluconeogenesis in rat liver.

1. The specific radioactivity-time relationships of glucose, glucose 6-phosphate, glycerol 1-phosphate and UDP-glucose were determined in rat liver after the intravenous injection of [U-(14)C]fructose, and a kinetic analysis was carried out. The glucose 6-phosphate pool was found to be compartmented into gluconeogenic and glycolytic components, and evidence was obtained that the triose phosphates were similarly compartmented. The glycolytic pathway was fed by glycogenolysis and glucose phosphorylation. There was no direct evidence that glycogenolysis fed only the glycolytic pathway, but this interpretation would make the liver resemble other organs in this respect. 2. UDP-glucose was not formed solely from gluconeogenic glucose 6-phosphate, as there was some dilution of label in the intervening glucose 1-phosphate pool, probably from glycogenolysis, though other pathways cannot be excluded. 3. The data cannot be explained by isotopic exchange.

The interaction of glycolysis, gluconeogenesis and the tricarboxylic acid cycle in rat liver in vivo.

1. The equations derived by Heath (1968) were applied to data from experiments on rats in four metabolic states: fed, post-absorptive, starved and 2hr. after an eventually lethal injury. The data used were: (a) The fractions of label injected as C1-, C2- and C3-pyruvate (where the prefix indicates the position of labelling) that are incorporated into carbon dioxide and glucose in post-absorptive and injured rats (yields). Yields could be corrected to yields on label taken up by the liver. (b) The (C5-label in glutamate)/(total label in glutamate) ratio in the liver after C2-pyruvate in rats in all four states. (c) The distribution of label within glutamate after C2-pyruvate or C2-alanine in the livers of fed, post-absorptive and starved rats. (d) The distribution of label within glucose after C2-lactate or C2-pyruvate in starved rats. (e) The relative specific radioactivities of pyruvate, aspartate, glutamate and (in two states only) of glucose 6-phosphate after injection of [U-(14)C]glucose into rats in all four states. These data were previously published, except those after (e) and some after (b) above, which are given in this paper. 2. In addition the concentrations of pyruvate, citrate, glutamate and aspartate in the livers of post-absorptive and injured rats were found. Injury decreased glutamate and citrate concentrations and to a smaller extent aspartate and pyruvate concentrations. 3. Non-steady-state theory showed that most of the data could be used without serious error in steady-state theory. Steady-state theory correlated all but one observation (the relative yields of (14)CO(2) from C2- and C3-pyruvate) listed after (a)-(e) above within the experimental errors, and gave rough estimates of the rates of pyruvate carboxylation, conversion of pyruvate and fat into acetyl-CoA and utilization of glutamate. The main conclusions were: (a) symmetrization of label in oxaloacetate both in the mitochondrion and in the cytoplasm was far from complete, because oxaloacetate did not equilibrate with fumarate in either. From this and other findings it was deduced: (b) that malate or fumarate or both left the mitochondrion, and not oxaloacetate; (c) that there was a loss from the mitochondrion of a fraction of the malate or fumarate or both formed from succinate, and (d) the resulting deficiency of oxaloacetate for the perpetuation of the tricarboxylic acid cycle was made up from pyruvate in fed and post-absorptive rats, but (e) in the starved rat could only be made up by utilization of glutamate. (f) In the fed rat the tricarboxylic acid cycle ran mostly on pyruvate, but in the post-absorptive and starved rat mostly on fat. (g) In the injured rat the tricarboxylic acid cycle was slowed, label in oxaloacetate was completely symmetrized (cf. conclusion a), and the tricarboxylic acid cycle utilized glutamate. (h) The conclusions were not invalidated by isotopic exchange, i.e. flux of label without net flux of compound, nor by interaction with lipogenic processes. (i) In the kidneys interaction between the tricarboxylic acid cycle and gluconeogenesis was different from in the liver, and was much less. The effects on the theory were roughly assessed, and were small. 4. The experiments and optimum experimental conditions required to check the theory are listed, and several predictions, open to experimental confirmation, are made.