Post-operative substrate utilisation and gas exchange using two different TPN-systems: Glucose versus fat

Determination of urinary 3-methylhistidine by high-performance liquid chromatography with o-phthaldialdehyde precolumn derivatization

A high-performance liquid chromatographic method to measure the concentration of 3-methylhistidine in human urine with o-phthaldialdehyde precolumn derivatization is described. A clear separation of the 3-methylhistidine derivative from other derivatives in urine was achieved within 25 min. The linearity, recovery and coefficients of variation were determined. The method was successfully applied to clinical assays and used for diagnostic purposes.

Splanchnic and peripheral release of 3-methylhistidine in relation to its urinary excretion in human infection

The present investigation was undertaken in order to determine the release of 3-methylhistidine (3MH) from the splanchnic region and from the leg, and the contributions these make to the increase in urinary 3MH excretion in infection. Thirteen febrile patients with infection were investigated. After an overnight fast, hepatic vein, femoral vein, and radial artery catheterizations were performed. Splanchnic and leg blood flows were determined by dye dilution technique. Plasma 3MH was analyzed by a modified HPLC method. The release of 3MH from the leg was 0.064 +/- 0.007 mumol/min (+/- SE) and from the splanchnic region 0.012 +/- 0.013 mumol/min. These releases of 3MH constitute 27% +/- 2% and 8% +/- 6% of the individual urinary excretions, respectively. With increasing degree of catabolism, measured as individual 3MH increase above baseline excretion or as the 3MH to creatinine ratio (3MH:Cr), the relative contribution to urinary excretion from the leg was increased (individual increase, P = 0.08; 3MH:Cr, P less than 0.01). Since this contribution was not decreased in the more catabolic patients, as would have been expected if the increase in urinary 3MH originated elsewhere, it is concluded that skeletal muscle is the source, and these results thus validate the use of urinary 3MH excretion as a marker of myofibrillar protein catabolism in infected patients.

Urinary excretion of 1-methylhistidine: a qualitative indicator of exogenous 3-methylhistidine and intake of meats from various sources

In order to investigate whether the urinary excretion of 1-methylhistidine (1MH) might serve as an objective indicator of meat ingestion and exogenous 3-methylhistidine (3MH) intake, healthy subjects were fed an ovolactovegetarian diet. At five-day intervals they were given meat of different origin and 24-hour urinary excretions of 1MH and 3MH were determined. After beef intake there was a marked increase of 3MH and 1MH excretion. The elimination curves were found to follow first-order kinetics and to indicate similar elimination rates. 1MH was present in ten different types of meat analyzed. A strong linear relationship was found between increase in 3MH and 1MH excretion and the amount of chicken, pork, or plaice ingested. IMH may serve as an objective indicator of meat and exogenous 3MH intake, since it is present in meat, and, regardless of source, shows similar dose-independent kinetics, and has similar half-life to 3MH.

Glucose balance and muscle glycogen during TPN in the early post-operative phase

In order to study how muscle glycogen is influenced by different nutritional regimens in the early post-operative period we took muscle biopsies from 20 patients preoperatively and on the fourth post-operative day after abdominal aortic surgery. Ten patients received 93% of non-protein energy as glucose, 7% as fat (Intralipid) and insulin was given to keep the blood glucose below 10 mmol/l. The remaining patients had 80% of non-protein energy as fat (Intralipid). Amino acids constituting 12 g of nitrogen daily were given to both groups. Daily measurements of gas exchange (oxygen uptake, CO2-production) were performed and from these data glucose balance was calculated as the difference between glucose intake and glucose expenditure. Muscle biopsies were analysed for glycogen, adenosine triphosphate, glucose-6-phosphate, lactate and citrate. We found that it was possible to maintain muscle glycogen stores at pre-operative levels with a glucose-insulin regimen. With the fat regimen there was a 31% decrease in muscle glycogen and two patients had a negative glucose balance despite the fact that 150 g of glucose were given. Average glucose balance throughout the study correlated positively with glucose intake. A significant correlation between glucose on the third day and change in muscle glycogen content was found. Muscle content of adenosine triphosphate, glucose-6-phosphate, lactate and citrate were similar in both groups.