Influence of total parenteral nutrition on protein metabolism following acute injury: assessment by urinary 3-methylhistidine excretion and nitrogen balance

Usefulness of Urinary Creatinine/Urea Nitrogen Ratio as Indicator of Body Protein Catabolism in Dogs Fed Low Protein Diets

Low protein diets (LPs) constitute a reportedly effective form of nutritional therapy for canine chronic kidney disease and cirrhosis. These diets have long been feared to result in reduced muscle mass due to protein catabolism. This adverse effect, however, remains largely unrecognized in veterinary medicine as there are no easily applicable catabolism indicators. Therefore, we focused on urinary creatinine, a metabolite of protein in the urine, and examined whether its ratio to urinary urea nitrogen (UCrn/UN) can be used to assess protein catabolism. In Experiment 1, we first consecutively fed seven healthy beagles an LP, standard protein (SP), and high protein (HP) diet for 1 week each and then measured the UCrn/UN ratio at 2-h intervals from fasting to 16 h post-prandially. We consequently found that the UCrn/UN ratio was significantly elevated in the LP pre-prandially and at all post-prandial measurement points (P < 0.01). No significant differences were observed between the SP and HP. Analysis of fasting plasma amino-acid concentrations revealed that the concentration of methionine was significantly lower in the LP than in the other diets (P < 0.05). Although the effects of this change in amino-acid concentration were unclear, the UCrn/UN ratio was considered having increased due to a deficiency in protein and/or amino acids during LP feeding. In Experiment 2, we continuously fed five healthy beagles an LP for 18 weeks and then measured the UCrn/UN ratio as described above. We also measured changes in body composition with computed tomography. At weeks 10 and 18, the fasting UCrn/UN ratio was significantly higher than it was prior to the start of the LP; however, post-prandially, the UCrn/UN ratio decreased to the point that the significant difference disappeared. Muscle mass decreased at weeks 10 and 18. These results suggest that the fasting UCrn/UN ratio could be used as an indicator of protein catabolism in LP feeding. Our experiments thus indicate that examination of potential increases in the UCrn/UN ratio 1 week after introduction of LP feeding to healthy dogs could enable detection of body protein catabolism in long-term feeding of LP before muscle breakdown occurs.

Tight glycemic control does not affect asymmetric-dimethylarginine in septic patients

OBJECTIVE

We investigated whether preventing hyperglycemia in septic patients affected the plasma concentration of asymmetric-dimethylarginine and if this was associated with clinical benefit.

DESIGN

A prospective, multicenter, randomized, controlled, clinical study.

SETTING

Intensive care units (ICU) in three university hospitals.

PATIENTS

A total of 72 patients admitted for severe sepsis or septic shock, who stayed at least 3 days in the ICU. At admission the patients were assigned to receive either tight or conventional glycemic control.

INTERVENTIONS

Determination of circulating levels of asymmetric-dimethylarginine, arginine, interleukin-6, C-reactive-protein and tumor-necrosis-factor-alpha.

MEASUREMENTS AND RESULTS

Blood was sampled at admission (no differences between groups), and on the 3rd, 6th, 9th, and 12th (T12) days. Sequential organ failure assessment was scored at each sampling time. All the data were analyzed on an intention-to-treat basis. The control and treatment groups received the same energy intake, glycemia (110.4 +/- 17.3 vs. 163.0 +/- 28.9 mg/dL, P < 0.001) and insulin (P = 0.02) supply differed. No differences were found in high plasma levels of asymmetric-dimethylarginine (P = 0.812) at any time during the ICU stay. The clinical course, as indicated by markers of inflammation, average and maximum organ failure score, ICU stay and ICU and 90-day mortality, was the same.

CONCLUSIONS

Intensive insulin treatment, while achieving glucose control, did not reduce asymmetric-dimethylarginine in high-risk septic patients fed with no more than 25 kcal/kg per day to limit ventilatory demand and to simplify glucose control.

DESCRIPTOR

45 (SIRS/sepsis: clinical studies).

Nutritional status and cytokine-related protein breakdown in elderly patients with gastrointestinal malignancies

BACKGROUND

Age-related factors affecting cytokine-related whole-body protein breakdown and their relation to clinical outcomes in cancer patients were investigated.

METHODS

For assessment of protein-calorie malnutrition and protein breakdown, the creatinine height index (CHI) and daily urinary excretion of 3-methylhistidine (3-MH) were measured in 70 patients with gastrointestinal malignancies. Perioperative cytokine profile was evaluated to assess its relation to perioperative protein catabolism.

RESULTS

In elderly patients, daily 3-MH excretion during the stable preoperative period decreased with the increase of tumor interleukin (IL)-6 production, suggestive of the activation of a metabolic compensation mechanism. However, these patients showed significant increases in postoperative 3-MH excretion in accord with perioperative systemic IL-6 response, and this deterioration of the compensating mechanism seemed to be associated with poor clinical outcome. An increase in 3-MH excretion under surgical stress was positively correlated with postoperative consumption of IL-6 soluble receptor (sR) in elderly patients with nutritional depletion.

CONCLUSIONS

In elderly cancer patients with protein-calorie malnutrition, metabolic compliance against intrinsic IL-6 may be compensated for in the preoperative stable period, but deteriorate from surgical insults. This mechanism might involve increased affinity of IL-6 with IL-6sR under surgical stress.

The effect of glutamine-supplemented total parenteral nutrition on nitrogen economy depends on severity of diseases in surgical patients

BACKGROUND

Gln is an important substrate for enterocyte and rapid proliferation cells. Studies have shown that parenteral supplementation of Gln maintains the intracellular Gln pool, improves nitrogen balance and shortens hospital stay. However, some studies showed Gln-supplemented TPN had no effect on restoring the Gln pool in critically ill patients.

OBJECTIVE

To evaluate the effect of glutamine (Gln) dipeptide supplementation of total parenteral nutrition (TPN) on postoperative nitrogen balance and immune response of patients undergoing surgery.

METHODS

This study is a prospective, randomized double-blind clinical trial. APACHE II score and TISS were used to evaluate the patients after admission. Forty-eight patients with major abdominal surgery were allocated to two groups to receive isonitrogenous (0.228 g nitrogen/kg/day) and isoenergetic (30 kcal/kg/day) TPN for 6 days. Two groups (Conv and Ala-Gln) were further divided to high (APACHE>or=6) and low (APACHE <6) groups. Control group (Conv) received 1.5 g amino acids/kg/day, whereas the Ala-Gln group received 0.972 g amino acids/kg/day and 0.417 g of L-alanyl-L-glutamine (Ala-Gln)/kg/day. Blood samples were collected on day 1 and day 6 after surgery for plasma amino acid and CD4, CD8 cell and T lymphocyte analysis. Cumulative nitrogen balance were also measured on day 2, 3, 4, 5 postoperatively.

RESULTS

Although there was a tendency to have better cumulative nitrogen balance on the postoperative days in the Ala-Gln group, no significant difference was observed between two groups. However, a better significant cumulative nitrogen balance was observed on the 2nd, 3rd and 5th postoperative day in the Ala-Gln group than in the Conv group in patients with APACHE II <6, whereas no significant difference was noted in patients with APACHE II >or= 6. No difference in urine 3-methylhistidine excretion were observed between the 2 groups. Patients in the Ala-Gln group had significant higher T lymphocyte and CD4 cells than did those in the Conv group.

CONCLUSION

TPN supplemented with Gln dipeptide had beneficial effect on enhancing the immune response. However, the effect of Ala-Gln administration on improving nitrogen economy was only observed in patients with low APACHE II scores. These results may indicate that Gln required for reversing the catabolic condition may depend on the characteristics and severity of the diseases.

Kinetic of body nitrogen loss during a whole day infusion and withdrawal of glucose and insulin in injured patients

OBJECTIVE

To investigate the kinetics of body nitrogen (N) excretion during 24 h glucose infusion (relating glycemia with insulin supply) and during subsequent 24 h saline infusion in injured patients during a full blown stress reaction. To define the lag time between the start of the withdrawal of glucose and insulin infusion, and the modification in the N loss from the body, and the time span to reach the maximum effect and its size. The knowledge of these variables is mandatory to plan short term studies in critically ill patients, while assuring the stability of the metabolic condition during the study period, and also to assess the possible weaning of the effect on protein breakdown during prolonged glucose and insulin infusion.

DESIGN

24-36 h after injury, patients were fasted ( < 100 g glucose) for 24 h (basal day). Thereafter, a 24 h glucose infusion in amount corresponding to measured fasting energy production rate (EPR), clamping glycemia at normal level with insulin supply followed by 24 h saline infusion, was performed. Total N, urea and 3-methyl-histidine (3-MH) in urine were measures on 4 h samples starting from 20th h of the basal day.

SETTING

Multipurpose ICU in University Hospital.

PATIENTS

6 consecutive patients who underwent accidental and/or surgical injury, immediately admitted for respiratory assistance (FIO2 < 0.04). Excluded patients were those with abnormal nutritional status, cardiovascular compromise and organ failures.

MAIN RESULTS

Patients showed a 33% increase in measured versus predicted fasting EPR and a consistent increase in N and 3-MH urinary loss. An infusion of glucose at 5.95 +/- 0.53 mg/kg x min (97.20 +/- 0.03% of the fasting measured EPR) with 1.22 +/- 0.18 mU/kg x min insulin infusion reduced N and 3-MH loss after a time lag of 12 h. The peak decrease in body N (-36%) and 3-MH loss (-38%) was reached during the first 12 h of glucose withdrawal period. Thereafter, during the following 12 h, the effect completely vanished confirming that it is therapy-dependent and that the metabolic environment of the patients did not change during the three days study period.

CONCLUSION

24 h glucose withdrawal reduces N and 3-MH loss injured patients, the drug-like effect is maintained during the first 12 h of withdrawal and thereafter disappears. The study suggests that at least a 24 h study period is necessary when planning studies exploring energy-protein metabolism relationship in injured patients, and, again 24 h before changing protocol in a crossover study.

Effects of human growth hormone in critically ill nonseptic patients: results from a prospective, randomized, placebo-controlled trial

OBJECTIVES

To study the effects of growth hormone administration on insulin-like growth factor I concentration, nitrogen balance, and fuel utilization, and to study its safety in critically ill nonseptic patients.

DESIGN

Prospective, randomized, placebo-controlled trial.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Eighteen critically ill nonseptic patients were studied for 8 days after admission.

INTERVENTIONS

Growth hormone (0.1 mg/kg/day) or placebo was administered as a continuous intravenous infusion on the second, third, and fourth days after admission. The study period was 8 days.

MEASUREMENTS AND MAIN RESULTS

Plasma hormone concentrations were measured every 6 hrs and average daily values were calculated. The 24-hr urinary nitrogen and 3-methylhistidine excretion were measured. Indirect calorimetry was used to calculate fuel utilization. Insulin-like growth factor I concentrations increased in the treatment group from subnormal to normal values and remained increased despite discontinuation of growth hormone treatment (p = .02). Nitrogen balance differed between the groups upon admission: growth hormone group (3.9 +/- 4.1 g/day) vs. controls (13.8 +/- 5.4 g/day), but improved with growth hormone. This finding appeared independent of the imbalance between the groups. The 3-methylhistidine excretion was not different between the groups and did not change during growth hormone administration. Free fatty acids and glycerol concentrations increased during growth hormone treatment, but calculated fuel utilization did not change. During growth hormone treatment, insulin concentrations increased, due to the increased administration of insulin necessary for glycemic control. Side effects other than hyperglycemia were not observed.

CONCLUSIONS

Growth hormone administration in a heterogeneous group of critically ill nonseptic patients resulted in normalization of insulin-like growth factor I levels, even after cessation of growth hormone treatment. Nitrogen balance improved, but this change was transient. Hence, growth hormone affects nitrogen balance, probably partly independent of insulin-like growth factor I.

Urinary excretion of polyamines in patients with surgical and accidental trauma: effect of total parenteral nutrition

Excretion of polyamines first increases and then decreases in patients with multiple trauma receiving total parenteral nutrition (TPN). To separate the effects of trauma and TPN on polyamine excretion, we studied 12 patients with multiple trauma and 14 patients after surgery for colorectal malignancy. Patients were randomized to receive either TPN or hypocaloric glucose infusion. Urinary excretion of total and free polyamines, putrescine (PU), spermidine (SPD), and spermine (SP), and their metabolites, N1-acetylspermidine (N1-AcSPD) and N8-acetylspermidine (N8-AcSPD), and energy and nitrogen balance were measured. Polyamine excretion, excluding SP, markedly increased after trauma and surgery, exceeding the normal values by twofold to 10-fold. In patients receiving TPN, the excretion of total polyamines was 48% higher (P < .01), PU was 34% higher (P < .05), SPD was 35% higher (P < .05), and SP was 350% higher (P < .05) than in patients receiving hypocaloric glucose. Urinary excretion of SP was only 17% of the reference value during hypocaloric glucose (P < .05), but was normal during TPN. The difference in polyamine excretion between nutrition groups was more pronounced when normalized for nitrogen or energy balance. Patients receiving TPN were more hypermetabolic than patients receiving hypocaloric glucose (resting energy expenditure, 1.36 +/- 0.06 [SE] and 1.16 +/- 0.04 times predicted values, respectively; P < .025). Statistically, energy expenditure could explain the difference in polyamine excretion between nutrition groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitrogen and energy balance in septic and injured intensive care patients: response to parenteral nutrition

We studied energy and nitrogen balance in 50 intensive care patients with sepsis (n = 18) or multiple trauma (n = 32). Most patients were mechanically ventilated during the study. Within 72h of admission the patients were randomised to receive one of 5 infusion regimens for 48h (group n = 9-11). The control group received hypocaloric glucose, two groups received 1.5g/kg/day of amino-acids, either with hypocaloric glucose on both days or with energy adjusted to pre-nutrition REE on the second day. The fourth group received 0.6g/kg/day of amino-acids and energy at REE, and the fifth group a high nitrogen (18g/day) regimen with a stepwise increase in energy intake from day 1 to day 2. Baseline REE was 118 +/- 18.9% of predicted. No significant differences in REE were observed between the diagnostic groups, treatments or measurements performed during mechanical or spontaneous ventilation. Nitrogen balance in the control group was -250.3 +/- 83.3 mg/kg on day 1 and 218.6 +/- 95.3 mg/kg on day 2. Nitrogen balance remained negative in all groups throughout the study (range of group means-218.6 to -48.5 mg/kg/day). Increasing energy intake equal to prenutrition REE at an amino-acid dosage of 1.5g/kg/day decreased the negative nitrogen balance by 66%. Further increase in energy balance had only a marginal effect on nitrogen balance.

Prospective study on the efficacy of branched-chain amino acids in septic patients

The metabolic response to sepsis is characterized by increased proteolysis and gluconeogenesis, reduced protein synthesis, and negative nitrogen balance. The effects of a solution with a high proportion of branched-chain amino acids (BCAA) on the nutritional state of septic patients were evaluated. Eighty patients with peritonitis were divided into two groups of 40 patients; group 1 was administered a solution with 22.5% BCAA and group 2 with 45% BCAA. The following parameters were evaluated: anthropometrics, creatinine/height index, urinary 3-methylhistidine, nitrogen balance, stress index, albumin, prealbumin, transferrin, retinol binding protein, lymphocytes, delayed cutaneous sensitivity tests, studies of hepatic function, and plasma aminogram. In group 2 a more positive nitrogen balance, a greater drop in the stress index, a rise in plasma prealbumin and retinol binding protein levels, an increase in the creatinine/height index, and a more marked fall in the urinary excretion of 3-methylhistidine were found. When solutions with a high BCAA content were administered, there was an increase in the plasma concentrations of these amino acids in the BCAA/aromatic amino acid quotient and a decrease in the aromatic amino acids. Plasma concentrations of leucine and valine achieved very high, potentially toxic, levels at 15 days when solutions with high BCAA content were used. It is concluded that solutions with BCAA are advisable for use in the septic patient in the increased protein catabolic phase, where positive nitrogen balance, a reduction in muscle protein catabolism, and faster recovery of muscle and visceral protein were obtained.

Parenteral nutrition for marrow transplant recipients: evaluation of an increased nitrogen dose

The use of total parenteral nutrition in bone marrow transplant (BMT) recipients is well recognized. These patients as a result of treatment with chemotherapy and immunosuppressive agents undergo catabolic stress. The metabolic effect of an increased nitrogen dose during total parenteral nutrition (TPN) was studied in 28 BMT patients. Patients were given TPN formulas providing a nitrogen intake of either 267 +/- 44 mg of N/kg/d or 330 +/- 60 mg of N/kg/d. Total calories, nonprotein and protein, were held constant at 40 kcal/kg/d for all patients. Data was collected for three periods posttransplant beginning at 3 days posttransplant through day 16. Both study TPN formulas improved patient weight and TIBC values over baseline. Nitrogen balance (NB) values were not significantly different at any study period. However, an overall group effect favored the H-N formula (p less than 0.01). BMT patients undergo catabolic stress which was reflected by average values of 24-hour urine urea nitrogen increasing from 8.1 +/- 4 g/d at baseline to 19.8 +/- 7.2 g/d at period 3 (p less than 0.01). The H-N formula did not differentially increase blood urea nitrogen or serum creatinine levels. Metabolic cart measures also showed no increase in metabolic rate, oxygen consumption, carbon dioxide production, or percent contribution of protein to total metabolic expenditure. Providing a caloric intake of 40 kcal/kg/d was excessive, where 30 to 35 kcal/kg/d would meet metabolic demands. Pertinent clinical outcomes including length of stay, relapse rate, and survival were monitored, but no conclusions could be drawn in this study. The H-N formula was more effective in reducing loss of lean body mass without causing detrimental metabolic effects in BMT patients.

Optimum branched-chain amino acids concentration for improving protein catabolism in severely stressed rats

In this study, an experiment was performed to investigate the optimal concentration of branched chain amino acid (BCAA) in hyperalimentation to be administered when protein catabolism is accelerated by sepsis or bodily injury. Amino acid solutions containing BCAA 25%, 30%, 40%, 45% and 50% were prepared and were administered iv for three days with other essential amino acid-containing nitrogen in the same volume into rats with peritonitis which had been developed by ligature and puncture at the cecum, and the results were compared. After observing for three days, the influence over nitrogen balance, improvement of 3-methyl-histidine/creatinine in urine, weight loss in muscles, and aminogram in serum and muscles indicated that the hyperalimentation under stress is utilized most effectively when amino acid contains 45% of branched-chain amino acid.

Essential and non-essential amino acid requirement in injured patients receiving total parenteral nutrition

The metabolic derangements of injury are known to influence nitrogen (N) requirements whilst less is known about individual amino acid (AA) requirements. This study was designed to investigate prospectively N vs AA requirement in 36 injured patients treated with total parenteral nutrition (TPN). The non-protein caloric input was 30 kcal kg-1 day-1 and three AA solutions were assessed containing the same AAs but in different proportion. Overall N intake was set at 0.35 g N kg-1 day-1 for solution A and B and 0.24 g N kg-1 day-1 for solution C. Solution B was similar to A, both being enriched in branched chain AAs (BCAA: 0.69 g kg-1 day-1 in B compared with 0.55 g kg-1 day-1 in A) while decreased in aromatic and sulphurated forms (1.75 times the normal need). Solution C was designed to maintain a daily input of BCAA similar to A (0.52 g kg-1 day-1) but with the supply of aromatic and sulphurated AA between solutions A and B, the supply of other AAs (lysine, theonine, histidine, arginine, glycine) being dependent on the selected N intake. For all the essential AAs the supply was always greater than normal allowances. Increasing BCAA over 0.55 g kg-1 day-1 did not improve N balance when N intake was 0.35 g kg-1 day-1, whilst nutrition with solution C was unable to maintain N balance. Moreover we found indirect evidence that this N intake, 0.52 g kg-1 day-1 was more sparing than 0.37 g kg-1 day-1 of BCAA.(ABSTRACT TRUNCATED AT 250 WORDS)

Carnitine excretion: a catabolic index of injury

In patients with trauma or sepsis, carnitine is known to be produced to a greater extent; deficient production could impair the energy management that is required in such patients. To clarify the requirements of carnitine after injury, we studied carnitine elimination (in 10 critically ill injured patients) both during fasting and early parenteral nutrition. Increased carnitine (mainly, free) output after injury (9.36 +/- 1.63 mumol/kg p less than 0.02 vs reference) was negatively related to nitrogen balance (p less than 0.05) and positively to 3-methyl-histidine output (p less than 0.01), acting as a market of body mass catabolism. The output of both total and free carnitine progressively decreased (p less than 0.01) throughout the course of total parenteral nutrition. In conclusion, our data definitively suggest that carnitine loss after injury reflects body cell mass wastage and does not necessarily mean an increased need.

Peripheral, visceral and body nitrogen balance of catabolic patients, without and with parenteral nutrition

The effect of major trauma and sepsis on skeletal muscle, central tissue and whole body nitrogen (N) metabolism was investigated in 5 patients before and during TPN (30 kcal, 0.30 g N kg-1 day-1). Fasting 3-methylhistidine (MEH) urinary excretion was elevated (407.9 +/- 67.6 mumol m-2 day-1), muscle and body N balances (NB) were markedly negative (-28.2 +/- 4.6 g m-2 day-1 and -15.7 +/- 3.1 g m-2 day-1), while central tissue NB was positive (13.0 +/- 2.4 g m-2 day-1). TPN effected a reduction in MEH excretion (261.8 +/- 27.5 mmol m-2 day-1 - p less than 0.05) and decreased the release of almost all amino acids from muscle tissue, some of them acting as catabolic markers. Muscle (-7.2 +/- 1.2 g m-2 day-1 - p less than 0.01) as well as body NB (-4.8 +/- 1.4 g m-2 day-1 - p less than 0.01) improved, whilst central tissue NB worsened, even though still positive (3.1 +/- 1.6 g m-2 day-1 - p less than 0.05). Gathering fasting and TPN data MEH excretion was significantly related to both body (r = 0.89) and muscle (r = 0.73) NB, that were highly related to each other (r = 0.93), being muscle always worse than body NB. In conclusion, the anticatabolic activity of TPN is confirmed, although our setting did not achieve muscle NB, it was consistently improved and seems to be the major determinant of body NB, in contrast central NB and central N utilization (46.4% +/- 5.4 vs 15.8% +/- 8.4 - p less than 0.05) worsened.

Clinical pharmacological and therapeutic considerations in general intensive care. A review

The application of clinical pharmacological concepts and therapeutic standards in intensive care settings presents particularly difficult problems due to the lack of adequately controlled background information and the highly variable and rapidly evolving clinical conditions where drugs must be administered and their impact evaluated. In this review, an attempt has been made to discuss the available knowledge within the framework of a problem-oriented approach, which appears to provide a more clinically useful insight than a drug-centred review. Following a brief discussion of the scanty data and the most interesting models to which reference can be made from a pharmacokinetic point of view (the burn patient being taken as an example), the review concentrates on the main general intervention strategies in intensive care patients. These are based mainly on non-pharmacological measures (correction of fluid and electrolyte balance, total parenteral nutrition, enteral nutrition, oxygenation and ventilatory management) and are discussed with respect to the specific challenge they present in various clinical conditions and organ failure situations. In addition, 4 major selected clinical conditions where general management criteria and careful use of prophylactic and therapeutic drug treatments must interact to cope with the variety of presentations and problems are reviewed. These include: acute cerebral damage; anti-infective prophylaxis and therapy; cardiovascular emergencies; and problems of haemostasis. Each problem is analysed in such a way as to frame the pharmacological intervention in its broader context of the underlying (established or hypothesised) pathophysiology, with special attention being paid to those methodological issues which allow an appreciation of the degree of reliability of the data and the recommendations which appear to be practiced (often haphazardly) in intensive care units. The thorough review of the published literature provided (up to mid-1986) clearly shows that in this field the quality of randomised controlled and epidemiological studies is rather unsatisfactory. It would be highly beneficial to research and to clinical care if larger multicentric protocols and prospective epidemiological comparative investigations could be carried out to investigate more timely and adequately the variables which determine drug action, and the final outcome in the many subgroups of patients which must be considered in a proper stratification of intensive care unit populations.

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.

Effects of intermittent electrical stimulations on muscle catabolism in intensive care patients

To determine whether muscular contractions obtained by electrical stimulation in immobilized patients are able to reduce muscle catabolism, we studied 10 patients (65-79 yr old) hospitalized in the intensive care unit for postoperative ventilatory failure or cerebral infarction. Artificial nutrition was the same for each patient during the 9-day study period. Two periods of 4 days were defined and randomized for each patient, separated by one day. During the muscular stimulation (MS) period, intermittent electrical stimulation of the muscles of the legs (external electrodes), were performed daily during 2 X 30 mn. During the other period, muscular stimulations were not performed. Urinary excretion of nitrogen (micro-Kjeldhal digestion and Nessler procedure), creatinine (Jaffe reaction), and 3-methyl histidine (3-MH) (gas phase chromatography) was measured every day. (table; see text) We conclude that a significant decrease in 3-MH and creatinine excretion is observed during the MS period. In intensive care unit patients, muscle protein breakdown may be influenced by intermittent muscular electrical stimulation.

[Effects of intermittent muscle stimulation on muscle catabolism in patients immobilized in the ICU]

Are muscular contractions obtained by electrical stimulation able to reduce muscle catabolism in immobilized patients? Ten patients (65 to 79 yr old), hospitalized in an intensive care unit for postoperative failure or cerebral infarction, were studied during nine days. Artificial nutrition was the same for each patient during the study. Two periods of four days where defined and randomized for each patient, separated by one day; during the stimulation period (S), intermittent electrical stimulation of the muscles of the legs (external electrodes) was performed daily 2 X 30 min; during the non-stimulation period (NS), muscular stimulation was not performed. Urinary excretion of nitrogen (micro-Kjeldhal digestion and Nessler procedure), creatinine (Jaffé reaction) and 3-methylhistidine were measured every day. Results (X +/- SD) are as follows: the nitrogen balance (g/d) was -1.29 +/- 1.26 during the NS period and 1.43 +/- 1.10 during the S period (NS); 3-methylhistidine (mumol/kg/d) was 3.78 +/- 0.37 during the NS period and 3.15 +/- 0.32 during the S period (p less than 0.01); creatinine (mumol/kg/d) was 92.9 +/- 6.8 during the NS period and 72.9 +/- 25 during the S period (p less than 0.01). It is concluded that a significant decrease in 3-methylhistidine and creatinine excretions is observed during the S period. In intensive care unit patients, muscle protein breakdown may be influenced by intermittent electrical muscle stimulation.