The samples derived from microdialysis were suitable to measure sub-peritoneal mediator profiles during surgery and up to 7 days postoperatively. Microdialysis data should be validated for a potential correlation with the clinical course.
Intravenous infusions of maltose were performed using human volunteers. Four volunteers received maltose in a dose of 0.25 g/kg bodyweight and hour during eight hours. A follow-up period of three hours was added. Six volunteers received maltose in a dose of 0.125 g/kg bodyweight and hour during twelve hours. Only with the lower dose of maltose (0.125 g/kg b.w.) a steady state is reached after six hour continuous infusion. However even under these conditions maltose concentration in blood reaches the high concentration of 70 mg/100 ml. Using the double infusion rate, no steady state is attained when the infusions lasted for eight hours, despite maltose concentration in blood measured 150 mg/100 ml at this time. By measuring different metabolic parameters (fatty acid concentration, phosphate concentration) it is shown that parenterally applicated maltose is metabolized in the human. On the other hand, adverse reactions were not observed. The concentrations of uric acid and bilirubin remain constant and the activity of SGOT is not altered. Renal excretion of sugar measures 25-35% of the maltose administered parenterally. It is concluded that the glucose in urine stems from direct intra tubular hydrolysis of maltose achieved by the neutral maltase of the kidneys. The lack of attaining constant blood concentration for maltose during the infusions and the high renal loss of sugar shows that maltose is not suited as the single substrate for parenteral nutrition. However, there remains the possibility to use maltose in combination with glucose substitutes. The metabolic behaviour of maltose is similar to glucose, it differs from glucose substitutes.
Glucose, fructose, sorbitol or xylitol were infused for four hours at different dose levels to metabolically healthy volunteers. The metabolic effects of the so-called glucose substitutes were compared to that of glucose. Even at very high doses (2.0 g/kg bodyweight per hour) of infusion of glucose or fructose a steady state was attained. This, however, was not the case with xylitol or sorbitol at lower doses (i.e. 0.5 g/kg bodyweight per hour), where no steady state was reached. The blood glucose concentration is not influenced by any of the glucose substitutes. During infusion of very high doses of fructose a small increase in serum insulin level is found, however, without any alteration in blood glucose concentration. Glucose as well as glucose substitutes cause an immediate suppression of free fatty acid concentrations in serum. In case of glucose there is a manifold increase in fatty acid concentration after the infusion is terminated. On the other hand, the free fatty acid concentration remains low even several hours following termination of the high-dosed fructose infusion. Theoretically one would expect an increase in triglyceride concentration, at least at the high dosed carbohydrate infusions. In contrast to this theoretical expectation, in the case of glucose and of xylitol a significant reduction of triglyceride concentration in serum was observed. Fructose and sorbitol did not exhibit this effect. Glucose and fructose are well utilized in metabolically healthy subjects. The maximum turnover rates for both polyols are lower. Unlike glucose, the glucose substitutes obviously do not cause any serious disturbation in hormonal regulations. Only in the case of glucose, counterregulation is seen following the termination of the infusion.
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