Ornithine alpha-ketoglutarate in trauma

Ornithine alpha-ketoglutarate improves wound healing in severe burn patients: a prospective randomized double-blind trial versus isonitrogenous controls

OBJECTIVE

To compare the effectiveness on wound healing time in severe burn patients of ornithine alpha-ketoglutarate supplementation of enteral feeding vs. an isonitrogenous control. Previous clinical and experimental studies suggest a beneficial effect of enterally administered ornithine alpha-ketoglutarate supplementation on protein metabolism in burn patients, but few data deal with clinical outcome.

DESIGN

Prospective double-blind randomized trial.

SETTING

Burn treatment center of an army hospital.

PATIENTS

Forty-seven severe burn patients with total burned body surface areas of 25% to 95% and presence of full thickness burn who were prescribed early exclusive enteral nutrition. Either ornithine alpha-ketoglutarate or isonitrogenous control (soy protein mixture, Protil-1) were administered twice a day as a bolus (2 x 10 g) at 9 am and 9 pm for 3 wks. The patients were evaluated for wound healing time (primary end point), antibiotic use, tolerance, duration of enteral nutrition, and nutritional status.

INTERVENTIONS

Serial blood samples were collected in each patient for determination of serum transthyretin and plasma phenylalanine, and urine sampling was performed for determination of 3-methylhistidine excretion at day 4 and day 21 after burn injury.

MEASUREMENTS AND MAIN RESULTS

Wound healing times in patients receiving ornithine alpha-ketoglutarate or Protil-1 were 60 +/- 7 and 90 +/- 12 days, respectively (p < .05) for similar grafted surfaces. Based on increased serum transthyretin concentrations, both groups showed an improvement of nutritional status at day 21 after burn. Taking a cut-off value of 110 unit burn standard for severity of injury, plasma phenylalanine concentrations, and urinary 3-methylhistidine/creatinine ratio were significantly reduced (p < .05) in the less severe burn patients (<110 unit burn standard) supplemented with ornithine alpha-ketoglutarate.

CONCLUSIONS

Ornithine alpha-ketoglutarate supplementation of enteral feeding significantly shortens wound healing time in severe burn patients. In addition, ornithine alpha-ketoglutarate administration was safe and well tolerated and decreased protein hypercatabolism in the less severe burn patients.

Modulation of immune response with ornithine A-ketoglutarate in burn injury: an arginine or glutamine dependency?

Enterally administered ornithine alpha-ketoglutarate (OKG) is an efficient complement of nutritional support in trauma situations, especially after burn injury. A typical feature observed in this intense catabolic state is insufficient production of glutamine (Gln) and arginine (Arg), two amino acids (AAs) involved in the immune response. As OKG in vivo metabolism generates these two AAs, we investigated, in burned rats, the action of OKG with regard to modulation of immunity. Male Wistar rats were randomly allocated to four groups. On day 0, 12 rats were burned with boiling water (20% body surface area). After a 24-h fast, they were enterally refed for 48 h using Osmolite, as a low-calorie low-nitrogen regimen, supplemented with either 5 g OKG x kg(-1) x d(-1) (n = 6) or an equivalent amount of nitrogen in the form of glycine (n = 6). Non-burned pair-fed controls treated with glycine (n = 6) and healthy rats fed ad libitum (n = 6) were also studied. Nitrogen balance was assessed from daily measurement of total nitrogen excretion. On day 3, thymus, Anterior tibialis muscle and proximal jejunum weights were recorded. Muscle and intestinal AA concentrations were also quantified. OKG counteracted (P<0.01) the thymic involution that occurs with burn injury, and increased the concentrations of Gln and Arg in both the muscle (P<0.01 and P<0.05, respectively) and the jejunum (P<0.01 for Gln). When all groups were taken together, a positive correlation was found between thymus weight, and Gln and Arg muscle concentrations (r = 0.71, P<0.001 and r = 0.58, P<0.01, respectively). Furthermore, as expected, OKG improved nitrogen balance. As it is known that total number of thymocytes parallels thymic weight, and as Gln and Arg are essential nutrients for activated immune cells, our results suggest that Gln and Arg derived from OKG are responsible for the immunomodulating properties of this molecule in burn injury.

Amino acids with anabolic properties

Experimental studies have clearly demonstrated both the indispensability in stress situations of amino acids, previously considered to be non-essential, and the importance of the specific properties of these same amino acids. Glutamine, arginine and their precursors/metabolites, ornithine and alpha-ketoglutarate, exert anabolic or anticatabolic effects through their involvement in protein metabolism, in the immune response and in cell proliferation. Clinical studies suggest that the supplementation of nutritional therapy with these amino acids can be of significant benefit for injured patients.

A randomized controlled trial of the influence of the mode of enteral ornithine alpha-ketoglutarate administration in burn patients

To investigate appropriate mode and daily dose of enteral ornithine alpha-ketoglutarate (OKG) administration, 54 burn patients (total burn surface area: 20-50%) were included in a randomized controlled trial and assigned to receive either a supplement of OKG (10, 20 or 30 g/d) as bolus or continuous infusion, or a continuous infusion of an isonitrogenous amount of a soy protein mixture (Protil-1: 10, 20 or 30 g/d) in addition to their enteral diet. The influence of these treatments on clinical outcome and biological indices was evaluated. OKG administration significantly improved nitrogen balance and reduced 3-methylhistidine and hydroxyproline urinary elimination. This was associated with a gradual rise in plasma glutamine over time. Given as a bolus, OKG significantly improved wound healing, assessed both clinically [day of last graft: (mean +/- SEM) OKG bolus 23.7 +/- 2.1 d versus Protil-1, 39.9 +/- 9.9 d; P < 0.05] and by hydroxyproline excretion, and biological markers of nitrogen metabolism, and tended to reduce duration of enteral nutrition (P = 0.12). The higher catabolic status in the patients administered 20 g OKG/d at the onset of the study, despite randomization, precludes any definite conclusion (concerning the dose-effect relationship). However, based on 3-methylhistidine elimination, our data indicate a benefit of 30 g OKG/d administration over 10 g/d. This study further supports OKG supplementation in burn patients. In addition, this is the first trial based on objective data that favors bolus over continuous infusion of OKG in critically ill patients.

Amelioration of the protein metabolic response in spermidine-supplemented trauma rats

Polyamines are biologically active, small, positively charged ubiquitous compounds that play an important role in initiating adaptive changes in cell proliferation, cell growth, and synthesis of proteins and nucleic acids. The potential for exogenous dietary polyamine to significantly contribute to whole-body growth and health has not been explored. This study evaluates the efficacy of feeding a liquid diet supplemented with 0.05% spermidine in injured rats. Rats traumatized by bilateral femur fracture (n = 12) and pair-fed uninjured controls (n = 12) were starved for 2 days and then refed for 4 days with a liquid diet containing 0.05% spermidine or an isonitrogenous control diet. Daily urine and body weight data were collected. At the end of refeeding, the rats were killed, and blood, cerebrospinal fluid (CSF), muscle, and brain tissue were collected. Spermidine supplementation (0.05%) was found to be tolerated well by the rats and (1) did not affect voluntary food intake by traumatized rats, (2) did not alter the growth rate, (3) increased protein utilization efficiency, and (4) decreased leucine, isoleucine, and valine levels in plasma and muscle. The profound effect of trauma on plasma amino acid metabolism seen in rats fed the basal diet was absent in spermidine-supplemented rats. Depletion of plasma glutamine (GLN) levels due to trauma was significantly less in rats with spermidine supplementation (11% v 33%), indicating a beneficial effect to counteract trauma responses. The results suggest that spermidine supplementation improves protein utilization efficiency and ameliorates trauma effects on amino acid levels.

Preventive administration of ornithine alpha-ketoglutarate improves intestinal mucosal repair after transient ischemia in rats

OBJECTIVES

To investigate whether the preventive enteral administration of a polyamine precursor, such as ornithine alpha-ketoglutaiate (OKG), has a beneficial effect on the repair process of the intestinal mucosa after transient mesenteric vascular occlusion.

DESIGN

A controlled laboratory study.

SETTING

A research laboratory facility at the Research Institute for Digestive Cancer.

SUBJECTS

Male Wistar rats, weighing 330 to 350 g, housed individually in plastic cages under standardized conditions (23 degrees C, 73 degrees F, 60% relative humidity, 12-hr light and 12-hr dark cycles).

INTERVENTIONS

Intragastrically, 1.5 or 17 hrs before surgery, animals received either distilled water (water group), or an amino acid solution of either OKG (1 g/kg) or L-lysine (0.68 g/kg) in distilled water under isonitrogenous conditions. Intestinal ischemia was produced in anesthetized rats by occluding the superior mesenteric artery for 90 mins with a microbulldog clamp. At the end of the ischemic period, the clamp was removed, allowing reperfusion, and the abdomen was closed.

MEASUREMENTS AND MAIN RESULTS

At 0, 4, and 24 hrs after ischemia/reperfusion, the midjejuno-ileum was resected. Intestinal morphology, polyamine content, and hydrolase activities were determined. In all groups at the end of the ischemic period, the villi were dismantled with preservation of the crypts. Rats treated with OKG exhibited a restoration of short villi by 4 hrs after ischemia/reperfusion. In other groups, the villi remained extensively denuded. By 24 hrs, only rats treated with OKG showed a complete recovery of normal mucosal architecture. The amount of the polyamines, putrescine, and spermidine were significantly enhanced by 4 hrs after ischemia/reperfusion in the mucosa of rats treated with OKG, as compared with the two other groups. At a functional level, sucrase and aminopeptidase activities remained significantly higher by 4 hrs of ischemia/reperfusion in rats treated with OKG as compared with rats receiving water or lysine. By 24 hrs, hydrolase activities were normalized in rats treated with OKG, whereas an important deficit in hydrolase activities remained in rats receiving either water or lysine.

CONCLUSIONS

OKG administration to rats did not prevent ischemic damage of the intestinal mucosa, but it accelerated the repair of the mucosa during reperfusion. OKG favored the restitution of normal villus architecture and the functional recovery of the intestinal mucosa. We hypothesized that OKG-triggered metabolites might mediate the restitution process and contribute to the healing of the intestinal mucosa by minimizing cell injury and by promoting the replacement of injured cells.

Ornithine alpha-ketoglutarate counteracts thymus involution and glutamine depletion in endotoxemic rats

This work studied the action of ornithine a-ketoglutarate (OKG) supplementation in an experimental model of endotoxemia in the rat. Male Wistar rats were injected intraperitoneally with lipopolysaccharide (LPS) from Escherichia coli (0127:B8). They were fasted for 24 h, then refed for 48 h with an enteral diet supplemented with either OKG (66 mg N x kg(-1) x d(-1)) or glycine, isonitrogenous to the OKG group. A control (sham) group was also studied. LPS treatment induced a decrease in thymus and muscle weights compared to controls, and a decrease in glutamine and arginine concentrations in the anterior tibialis muscle. Supplementation with OKG restored thymus weight and muscle arginine level and increased muscle glutamine concentration, when compared to controls. We conclude that OKG counteracts the thymic involution that occurs with endotoxemia, and restores the muscular content of glutamine and arginine, both of which are involved in the regulation of immune function.

Adjuvant recombinant human growth hormone does not augment endogenous glucose production in total parenteral nutrition-fed multiple trauma patients

Hyperglycemia and insulin resistance are well-known, consistent responses to severe injury. The purpose of this study was to investigate the mechanism for the further exaggerated hyperglycemia due to adjuvant recombinant human growth hormone (rhGH) treatment in multiple trauma patients. We have measured in 20 adult severely injured, highly catabolic, hypermetabolic multiple trauma patients, the glucose kinetics (appearance, clearance, oxidation, and recycling) once in the basal state (study I), 48 to 60 hours after injury but before starting nutritional therapy, and again (study II) after 7 days of intravenous nutrition (1.1 times resting energy expenditure, 250 mg nitrogen [N]/kg/d) with or without adjuvant rhGH. Group H (n = 10) randomly received daily (8 AM) rhGH (0.15 mg/kg/d) and group C (n = 10) received the vehicle of infusion. Adjuvant rhGH treatment in intravenously fed trauma patients (1) increases plasma insulin-like growth factor-1 (IGF-1) and insulin concentrations, (2) improves N balance, and (3) exaggerates the hyperglycemic response without affecting endogenous glucose output, glucose oxidation, or recycling. The mechanism for the hyperglycemic hyperinsulinemia in trauma may be due to a defective nonoxidative glucose disposal, as well as inhibition of glucose transport activity into tissue cells.

Functional and metabolic changes in intestinal mucosa of rats after enteral administration of ornithine alpha-ketoglutarate salt

BACKGROUND

Ornithine alpha-ketoglutarate salt efficiently improves the nutritional status of protein-depleted patients. Our aim was to explore the effects of ornithine alpha-ketoglutarate supplementation on intestinal physiology in healthy animals.

METHODS

Rats were given a nutritive mixture supplemented with ornithine alpha-ketoglutarate (1 g.kg-1 per day) by enteral route for 7 days. Controls received the diet supplemented with casein acid hydrolysate under isoenergetic and isonitrogenous conditions.

RESULTS

An adaptive hyperplasia of the villi and an increase in the brush-border hydrolase activities were observed in rats receiving ornithine alpha-ketoglutarate. Because of the high ornithine aminotransferase activity, ornithine alpha-ketoglutarate-derived ornithine was extensively transaminated with a concomitant enhancement of ornithine decarboxylation. Surprisingly, with glutamate and putrescine, the products of ornithine transamination and decarboxylation, gamma-aminobutyric acid accumulated (10-fold to 16-fold) dramatically in the intestinal mucosa of rats treated with ornithine alpha-ketoglutarate. Because gamma-aminobutyric acid formation was completely prevented by the diamine oxidase inhibitor aminoguanidine but was not modified after inactivation of ornithine aminotransferase by 5-fluoromethylornithine, it is evident that gamma-aminobutyric acid is formed in the mucosa from ornithine via putrescine as an intermediate.

CONCLUSIONS

It is assumed that enhanced gamma-aminobutyric acid formation in the intestinal mucosa by ornithine alpha-ketoglutarate treatment might be of physiologic importance in the regulatory processes of cell growth and differentiation.

Endogenous ornithine in search for CNS functions and therapeutic applications

The vertebrate brain has the machinery to transport arginine and ornithine, and to form within nerve endings from these amino acids glutamate and GABA, the major excitatory and inhibitory neurotransmitters. Ornithine aminotransferase is a key enzyme of the Arg-->Orn-->Glu-->GABA pathway; the physiological significance of this pathway is still unclear. With 5-fluoromethylornithine, a selective inactivator of ornithine aminotransferase, a tool is in our hands that allows us to study biochemical and behavioral consequences of elevated tissue ornithine concentrations. Increase of the rate of hepatic urea formation, and of ornithine decarboxylation are the most important changes in vertebrates following inactivation of ornithine aminotransferase. Administration of 5-fluoromethylornithine prevented the accumulation of lethal concentrations of ammonia in brain, and ameliorated pathological consequences of thioacetamide intoxication. Inhibition of ornithine catabolism has, therefore, potentials in the therapy of those hyperammonemic states which are characterized by a conditional deficiency of ornithine. The enhancement of polyamine formation due to elevated ornithine concentrations may allow us to favorably affect tissue regeneration following injury.