Altered tissue polyamine levels due to ornithine-alpha-ketoglutarate in traumatized growing rats

Glucose transport in fibroblasts is unaffected by polyamines

OBJECTIVE

Wound healing is characterized by a net increase in glucose utilization in wound tissues. The mediators involved in this process remain largely unknown. Because polyamines are known to stimulate d-glucose uptake in brush-border membrane vesicles, we investigated whether or not they stimulated sugar uptake in confluent cultured fibroblasts.

METHODS

Cells (at a quiescent or growing state) were incubated for 1 h with various concentrations (0.5-4 mM) of putrescine, spermine, or spermidine or for a range of times (30 min to 3 h) with 2 mM of these same polyamines. Cultures were then incubated for 5 min at +37 degrees C with 2-deoxy-d-[1-(3)H] glucose.

RESULTS

Polyamines were found to have no action on sugar uptake in any of the experimental configurations.

CONCLUSION

These data suggest that polyamines have no effect in cell types in which glucose uptake is mediated by a passive facilitated diffusion process (energy independent). This contrasts with results obtained with cells in which sugar uptake is dependent on adenosine triphosphate. Even if this model does not reflect the complexity of wound healing, these negative results are nevertheless important because they suggest that the arginine- and ornithine-mediated effects on wound healing are not related to a polyamine-mediated increase in glucose transport in fibroblasts.

Dose dependency of the effect of ornithine α-ketoglutarate on tissue glutamine concentrations and hypercatabolic response in endotoxaemic rats

The optimal dosage of ornithine α-ketoglutarate (OKG) for repleting tissue glutamine (Gln) concentrations and maintaining N homeostasis after injury is unknown. We set out to perform ‘dose-ranging’ of OKG supplementation after an endotoxaemic challenge. Sixty-one male Wistar rats were injected with 3 mg lipopolysaccharide (LPS) from Escherichia coli/kg (n 50) or saline vehicle (9 g NaCl/l; controls n 11). After a 24 h fast, survivors were fed by gavage for 48 h with a polymeric standard diet (879 kJ/kg per d and 1·18 g N/kg per d) supplemented with non-essential amino acids (control, n 11; LPS-OKG-0·0, n 9), or with 0·5 g OKG/kg per d (LPS-OKG-0·5, n 12), 1·5 OKG/kg per d (LPS-OKG-1.5, n 11) or 4·5 g OKG/kg per d (LPS-OKG-4·5, n 10). The diets for all groups were made isonitrogenous with the LPS-OKG-4·5 diet by adding an appropriate amount of non-essential amino acids. Rats were killed on day 3 for blood and tissue sampling (muscle, jejunum mucosa, liver). Urine was collected daily for 3-methylhistidine and total N assays. The OKG dose was correlated with Gln concentrations in every tissue and with cumulative N balance (Spearman test, P<0·01). 3-Methylhistidine excretion was increased in endotoxaemic groups compared with controls (ANOVA, P<0·05) except in the LPS-OKG-4·5 group. Only the LPS-OKG-4·5 group achieved a positive post-injury N balance (t test, P<0·05). In conclusion, OKG exerted a dose-dependent effect on tissue Gln concentration and N balance, but only the highest dosage counteracted myofibrillar hypercatabolism and caused a positive N balance.

Ornithine alpha-ketoglutarate supplementation influences motor activity in healthy rats

BACKGROUND

Ornithine alpha-ketoglutarate (OKG) improves nutritional status in malnourished patients. Published and unpublished data suggest OKG may have effects on the central nervous system that may contribute to its action.

OBJECTIVE

We investigated the effect of an OKG-enriched diet on behaviour in healthy rats.

DESIGN

Thirty male Wistar rats were randomised in three groups: the OKG group was fed for 5 days (D0-D5) at 90% of spontaneous food intake with an OKG-enriched diet (5 g/kg/d). The non-essential amino acids (NEAA) group was fed similarly with a regimen enriched with NEAA (glycine, alanine, histidine and serine) to be isonitrogenous to OKG group. The ad libitum (AL) group had no treatment and was fed ad libitum with a standard regimen throughout. Rats were tested at D4 for motor activity by actimetry, and at D5 first for spontaneous alternation behaviour measured in the Y-maze, and then for exploratory behaviour measured using the open-field test (stressful environment).

RESULTS

We found that OKG supplementation enhanced global motricity by actimetry (AL 772 +/- 55, NEAA 811 +/- 54 vs. OKG 966 +/- 24 arbitrary units, P < 0.05) and total numbers of arms visited in the Y-maze (AL 26 +/- 2, NEAA 30 +/- 3 vs. OKG 38 +/- 3, P < 0.05). The lack of any effect of the OKG-enriched diet in the open-field test shows that the enhancement of locomotion activity was most probably not due to an increase in anxiety or fear in the rats.

CONCLUSION

An OKG-enriched diet can induce beneficial stimulant effects that may be involved in the mechanism of action of OKG.

Clinical role of polyamine analysis: problem and promise

Polyamines are ubiquitous cell components for growth. They play an important role in cell proliferation, cell growth and synthesis of protein and nucleic acids. Cells that are stimulated to reproduce demonstrated early increases in biosynthetic enzymes involved in polyamine synthesis and subsequent elevations in polyamine levels. Extracellular fluid polyamine concentrations that reflect the intracellular events may be useful as rapid indicators of therapy in disorders which involve altered cell growth. More complex analytical approaches are required to isolate, identify and quantitate these polyamines. Most of the methods require an extraction procedure to remove interfering amino acid derivatives. Daily monitoring of plasma and urine polyamine levels in many pathological states may provide a non-invasive biochemical marker of the existing disease activity or response to therapy or to screen for drug efficacy. Automated high-performance liquid chromatography, with post or pre-column derivatization and fluorescence or electrochemical detection is frequently used for the simultaneous quantitation of picomolar quantities of polyamines. Recently, a new immuno-cytochemical model system incorporating an enzyme-linked immunosorbent assay for specific polyamines has been developed. The increasing momentum of basic science information in the polyamine discipline may lead clinicians to regard polyamines, their metabolites and antimetabolites as sources of effective treatment.

Fasting gastric fluid and fecal polyamine concentrations in premature infants

BACKGROUND

The role of milk polyamines in the development of the gastrointestinal tract of human infants is presently unknown. Polyamine concentrations are higher in human milk than in infant formulas. The aim of the present study was to gather data on luminal polyamines by measuring gastric fluid and fecal polyamine concentrations in premature infants during the postnatal period. We further compared gastric fluid polyamine concentrations with those reported for milk and looked for possible relationships between luminal polyamine concentrations, age, and growth rate.

METHODS

High-performance liquid chromatography was used for the measurement of polyamine concentrations in both fecal and gastric fluid samples.

RESULTS

Ninetieth centiles for gastric polyamines during the first week were 62, 28, 82, and 14 microM for putrescine, spermidine, spermine, and cadaverine, respectively. These values are higher than those reported for human milk and infant formulas. Polyamine concentrations were unrelated to either age or growth rate. Ninetieth centiles for fecal polyamines during the first week were 7668, 5176, 53, and 75 microM for cadaverine, putrescine, spermidine, and spermine, respectively.

CONCLUSIONS

Fasting gastric fluid polyamine concentrations in premature infants are higher than those reported for either human milk or infant formulas. The high fecal cadaverine and putrescine concentrations are probably of bacterial origin.

Effect of oral supplementation of ornithine-alpha-ketoglutarate on the intestinal barrier after orthotopic small bowel transplantation

The aim of this study was to analyze the possible protective effects of a glutamine and arginine precursor (ornithine-alpha-ketoglutarate [OKG]) on the mucosa of a transplanted intestine when administered with either a defined formula oral diet (DFD) or a standard chow. Isogenic male Lewis rats (250 g) were submitted to a laparotomy (groups 1 and 2) or to an orthotopic small bowel transplantation (SBT; groups 3-6). Groups 1, 3, and 5 received a DFD 14 days after surgery. Groups 2, 4, and 6 received standard chow. In addition, groups 5 and 6 received a daily oral supplementation of 1.4 g/kg of OKG. Weight changes and food intake were recorded daily. At the end of the study, bacterial translocation (BT) was measured in mesenteric lymph nodes, liver, and spleen. The protein/DNA index was also determined in intestinal mucosa. SBT induced BT in all transplanted groups, especially in those fed DFD. Addition of OKG (groups 5 and 6) significantly reduced BT in comparison with groups 3 and 4 and improved the protein/DNA index as well as weight gain. It is concluded that OKG supplementation protects the intestinal barrier after SBT, and that this effect is more marked when it is added to a standard chow.

Automated determination of polyamines by high-performance liquid chromatography with simple sample preparation

Recently, a new fully endcapped reversed-phase packing material, Inertsil, was introduced, especially suitable for the determination of basic compounds. We used this packing material to separate ophthaldialdehyde (OPA) derivatives of amino acid derivatives completely from the OPA derivatives of spermine (SPM), spermidine (SPD), putrescine (PUT) and cadaverine (CAD). The obtained separation made the commonly used off-line extraction procedure redundant and thus an on-line sample clean-up was introduced. This enabled automation of the procedure resulting in a better reproducibility and a more efficient use of equipment. Furthermore, no studies are required to determine the extraction recovery. The present method has a cycle time of 30 min. A linear response for each polyamine was found up to 250 pmol, with an R2 ranging from 0.9981 (SPM) to 0.9998 (CAD). The limit of detection, calculated at a signal-to-noise ratio of 3, was 0.1 pmol, corresponding to a plasma concentration of 0.1 mumol/l. The coefficient of variation (C.V.) for the peak area was below 3% and for retention times below 0.5% (n = 15). In order to evaluate the applicability of the method, three different types of sample were chromatographed, e.g. urine (obtained from healthy human volunteers), pig plasma and sulfosalicylic acid homogenates of pig intestine biopsies. Tissue homogenates and urine-specimen could easily be quantitated, while plasma concentrations were just above the limit of detection, resulting in a plasma C.V. ranging from 4.8% (SPM) to 13.6% (SPD) and a tissue C.V. ranging from 2.1% (SPM) to 8.5% (CAD), The urinary C.V.s were not determined. In conclusion, the present method provides an easy way to measure polyamine concentrations for most applications.

Influence of diet with or without amino acids on polyamine excretion in multiple trauma victims

Elevated levels of urinary polyamines (PA) in severely injured trauma patients are further enhanced by total parenteral nutrition (TPN) that contains both glucose and amino acids (AAs). Since TPN solutions contain arginine, the AA precursor of PA, it is not certain whether the increased urinary PA are due to this substrate. Nutritional factors can evidently modify PA metabolism. We measured the daily excretion of the PA, putrescine (PU) and spermidine (SD) in 18 multiply injured (injury severity score [ISS], 32 +/- 2), hypermetabolic (resting energy expenditure [REE]/basal energy expenditure [BEE], 1.41 +/- 0.06), and highly catabolic (daily N loss, 17.2 +/- 1.8 g N/d) acute trauma patients for 5 days in the early flow phase of injury. The patients were fed only maintenance fluids without calories or nitrogen for the first day 60 to 72 hours after injury, and then were randomized to receive glucose alone ([GLUC] 4.1 mg/kg/min, 80% measured REE, n = 8) or the same amount of glucose with AAs (TPN, 275 mg N/kg/d, n = 10) for the following 4 days. There was no significant difference in the enhanced daily PA excretion either in the free or acetylated form between the two dietary regimens. The addition of AAs in the TPN mixture did not seem to further stimulate PA metabolism in the trauma patients. The source of the nutrient content of the diet appears to be important for enhancing total PA excretion in critically ill patients.