[Utilization of glycogen phosphorylase BB measurement in the diagnosis of acute coronary syndromes in the event of chest pain]

INTRODUCTION

Glykogen Phosphorylase BB is considered a timely and specific marker of acute coronary syndrome. A kit for measuring Glykogen Phosphorylase BB in routine diagnosis has been released recently.

OBJECTIVE OF THE STUDY

To test the utilisation of Glykogen Phosphorylase BB measurement in the diagnosis of acute coronary syndrome.

METHOD

70 patients with suspected acute coronary syndrome were tested. A final diagnosis of acute coronary syndrome/non-coronary difficulties was made according to ESC/ACC/AHA criteria. Measurements of troponin I, myoglobin and GPBB in venous plasma (heparin-lithium) were taken for all probands on admission and two and six hours later.

RESULTS

Individuals with acute coronary syndrome (n = 52) had significantly higher levels of Glykogen Phosphorylase BB on admission and 2 hours after admission (21.9 vs 6.2; 18.7 vs 5.9 microg/l; p < 0.01). Levels of Glykogen Phosphorylase BB had a greater diagnostic effectiveness for the presence of acute coronary syndrome than levels of troponin I (threshold below ROC curve 0.89 vs. 0.78; 0.87 vs. 0.67). In the first two hours after admission, only levels of Glykogen Phosphorylase BB were included as independent variables in the regression model for the incidence of acute coronary syndrome (p < 0.05). When the group of patients with myocardial necrosis (n = 39; acute myocardial infarction without ST elevations on ECG; NSTEMI) is removed from the group with acute coronary syndrome, it was found that only GPBB and cTnl were independent variables in the regression model on initial testing and after two hours. After adjusting GPBB to cTnl, significantly higher levels of GPBB adjusted to troponin I were found in persons with NSTEMI (14.5 vs -48.0; p < 0.01).

CONCLUSION

Measurement of Glykogen Phosphorylase BB has excellent effectiveness independently of troponin in the first hours after the onset of acute coronary syndrome and should ensure the correct diagnosis of acute coronary syndrome in combination with troponin.

Proguanylin: development, analytical characterization, and clinical testing of a new ELISA

The aim of our work was to develop an assay for the determination of proguanylin in human blood, and investigate its levels in healthy volunteers and donors suffer from hypertension often accompanied by body sodium accumulation and plasma volume expansion. We developed and evaluated the sandwich ELISA method for the quantitative determination of human proguanylin in serum samples. We conducted also the pilot study on individuals with hypertension and oh healthy probands and measured proguanylin serum levels, serum and urine sodium and creatinine levels. In the study on 256 healthy volunteers we demonstrated that women have significantly higher values of proguanylin than men (medians 12.7 vs. 9.6 ng/ml, p < 0.01) and proguanylin values increased with age of individuals (p < 0.01). Futhermore, we tested 17 individuals with hypertension and found that probands with anamnesi of hypertension had higher proguanylin values than healthy individuals from the first study (medians 16.2 vs. 11.3 ng/ml, p < 0.01). Both of groups did not differ in sex or age. Proguanylin values correlated with the systolic blood pressure (r = 0.41, p < 0.01), sodium fraction excretion (r = 0.72, p < 0.01) and serum sodium (r = -0.39, p < 0.01). No significant correlation we found with serum proguanylin and creatinine. In the group of 9 healthy probands we demonstrated the existence of a diurnal rhythm of proguanylin with its maximum in the evening hours (between 6-10 p.m.). The pilot study supports the hypothesis about the role of proguanylin in sodium metabolism and its possible importance for hypertension disorder. Further research is necessary to confirm our findings in individuals with hypertension with different medication in order to assess proguanylin value as a risk predictor of accelerated hypertension, and to classify individuals with hypertension for variuos types of diuretic therapy.

Effect of acute acidosis on protein and amino acid metabolism in rats

BACKGROUND & AIMS

Metabolic acidosis is a common finding in critical illness. The aim of the present study was to evaluate acute acidosis as a signal that induces changes in protein metabolism.

METHODS

In the first study, Wistar rats were infused for 6h with HCl or saline resulting in blood pH7.30+/-0.03 and 7.46+/-0.02, respectively. The whole body protein metabolism was evaluated using L-[1-(14)C]leucine. In the second study, soleus and extensor digitorum longus muscles from normal rats were incubated in medium, pH7.4, 7.3 or 7.0. Protein metabolism was evaluated using L-[1-(14)C]leucine and tyrosine release.

RESULTS

In the in vivo study we observed increased protein turnover-protein synthesis, proteolysis and leucine oxidation and more negative protein balance in rats with acidosis. There was no change in protein synthesis in gastrocnemius muscle. We observed an increase in plasma levels of most amino acids including branched-chain amino acids and a decrease in intracellular amino acid pool in skeletal muscle. In vitro decrease in pH of 0.1 had no effect on protein metabolism, decrease of 0.4 decreased protein turnover and leucine oxidation.

CONCLUSION

Acute metabolic acidosis is a protein wasting condition. Direct effect of acidosis on skeletal muscle is under condition in vivo modified by neurohumoral regulations.

Inflammatory response and tissue trauma in laparoscopic hysterectomy: comparison of electrosurgery and harmonic scalpel

OBJECTIVE

Our aim was to quantify and compare clinical outcome and surgical inflammatory response and tissue trauma after laparoscopic hysterectomy for a benign disorder which was performed by electrosurgery or harmonic scalpel.

METHODS

Sixty patients scheduled for laparoscopic hysterectomy were selected according to patient preference to undergo either electrosurgery or an ultrasonic operative technique. Blood samples for assay of markers of tissue trauma (C-reactive protein, interleukin-6, creatine kinase, white blood cell count) were taken preoperatively, on the first and third postoperative day. Three patients with intraoperative complications or incomplete records were excluded from tissue analysis.

RESULTS

No differences were present in the demographic characteristics and clinical outcomes (blood loss, uterine weight, operating time and hospital stay) in 57 uncomplicated laparoscopic hysterectomies. Both electrosurgery (n = 36) and use of the harmonic scalpel (n = 21) resulted in statistically significant changes in the inflammatory and systemic immune response in comparison with preoperative values. No significant differences were observed in the studied inflammatory and tissue markers (C-reactive protein, interleukin-6, creatine kinase and white blood cells) between the compared groups.

CONCLUSION

The harmonic scalpel and electrosurgery in laparoscopic hystsrectomy were equally traumatic in terms of surgical inflammatory response and tissue trauma.

Effect of alanyl-glutamine on leucine and protein metabolism in irradiated rats

The mechanism by which glutamine produces a favorable effect in the treatment of sepsis, injury, burns and abdominal irradiation is not completely understood. The main aim of this study was to evaluate the effect of alanyl-glutamine (AlaGln) administration on the metabolism of proteins in irradiated rats. The rats were exposed to whole-body irradiation (8Gy) and then fed intragastrically with a mixture of glucose and amino acids either with AlaGln or without AlaGln. At 48 hours after irradiation, parameters of whole-body protein metabolism and DNA synthesis in intestinal mucosa were investigated using a primed, continuous infusion of [1-14C]leucine and [3H]thymidine. In addition, we evaluated the effect of irradiation and AlaGln on gut morphology, blood count and amino acid concentrations in blood plasma and skeletal muscle. Control rats were not irradiated but were given identical treatment. An increase in whole-body leucine oxidation, and insignificant changes in whole-body proteolysis and in protein synthesis were observed after irradiation. In irradiated rats we observed a decrease in muscle glutamine concentration, a decrease in protein synthesis in jejunum, colon and heart, and an increase in synthesis of proteins of blood plasma and spleen. Morphological examination and measurement of DNA synthesis failed to demonstrate any favorable effect of AlaGln supplementation on irradiated gut. However, administration of AlaGln resulted in a decrease in whole-body proteolysis and leucine oxidation which caused an increase in the fraction of leucine incorporated into the pool of body proteins. We conclude that the data obtained demonstrate that irradiation induces metabolic derangement associated with increased oxidation of essential branched-chain amino acids (valine, leucine and isoleucine) and that these disturbances can be ameliorated by administration of AlaGln.

Clinical outcome, inflammatory response and tissue trauma in total laparoscopic hysterectomy: comparison to laparoscopically-assisted vaginal hysterectomy

OBJECTIVE

Our aim was quantify and compare the clinical outcome and surgical inflammatory response and tissue trauma between the total laparoscopic hysterectomy (TLH) and laparoscopically-assisted vaginal hysterectomy (LAVH).

DESIGN

Clinical study.

SETTING

Departments of Gynaecology, Obstetrics and Biochemistry, Hospital Kladno, Department of Biochemistry, Faculty Hospital Motol-Prague.

METHODS

Fifty-eight patients scheduled for laparoscopic hysterectomy were selected according patients or doctor preference to undergo either TLH or LAVH operative technique. Blood samples for assay of markers of tissue trauma (C-reactive protein, interleukin-6, creatine kinase, cortisol, cystatin C, serotonin and white blood cells count) were taken preoperatively, on the first and third postoperative day. One patient with intraoperative complication (ureteral injury) was excluded from tissue analysis.

RESULTS

No differences were present in the demographic characteristics and clinical outcomes (blood loss, complications and hospital stay) in fifty seven laparoscopic hysterectomies. The statistically significant difference was found only in duration of surgery (70 min in TLH group vs. 90 min in LAVH group, P < 0.05). This difference can be related to difference in uterine specimen weight (185 g in TLH group vs. 289 g in LAVH group, P < 0.02). Both the LAVH (n = 37) and TLH (n = 20) resulted in statistically significant changes in the inflammatory and systemic immune response in comparison with preoperative value. No significant differences were observed in the studied inflammatory and tissue markers between the studied operative techniques of laparoscopic hysterectomy.

CONCLUSION

The total laparoscopic hysterectomy and laparoscopically-assisted vaginal hysterectomy were equally traumatic in terms of surgical inflammatory response and tissue trauma.

[Parenteral nutrition in catabolic states using Neonutrin 15%, a new amino acid solution]

Development of amino acid solutions for i.v. use proceeds worldwide, the main stimulus being the expanding physiological and pathophysiological findings of specific effects of some amino acids and their metabolism and the need to improve intensive metabolic care. New Czech preparations in this respect are the series of NEONUTRINS 5%, 10% and 15% (Infusia Ltd. Horátev). They are modern preparations which meet the pretentious criteria of contemporary amino acid solutions (balanced ratio of all essential, semiessential and assisting amino acids, a high content of essential and branched-chain amino acids, amino acids with specific pharmacodynamic effects). In a multicentre open clinical study the authors assessed the tolerance, safety and efficacy of NEONUTRIN 15% in 82 patients requiring total parenteral nutrition on account of catabolic states of different etiology. The preparation was administered repeatedly in an all-in-one mixture (together with glucose and lipid emulsions) by means of a central venous catheter. A total of 801 doses was administered. The trial provided evidence of very good tolerance and safety of the preparation with a practically zero incidence of undesirable effects. The follow-up of basic indicators of nitrogen metabolism confirmed also the efficacy of NEONUTRIN 15% in comprehensive treatment of patients (stabilization of nitrogen balance in the acute stage of a disease, normalization of the plasmatic aminogram).

Metabolism of branched-chain amino acids in starved rats: the role of hepatic tissue

Parameters of branched-chain amino acids (BCAA; leucine, isoleucine and valine) and protein metabolism were evaluated using L-[1-(14)C]leucine and alpha-keto[1-(14)C]isocaproate (KIC) in the whole body and in isolated perfused liver (IPL) of rats fed ad libitum or starved for 3 days. Starvation caused a significant increase in plasma BCAA levels and a decrease in leucine appearance from proteolysis, leucine incorporation into body proteins, leucine oxidation, leucine-oxidized fraction, and leucine clearance. Protein synthesis decreased significantly in skeletal muscle and the liver. There were no significant differences in leucine and KIC oxidation by IPL. In starved animals, a significant increase in net release of BCAA and tyrosine by IPL was observed, while the effect on other amino acids was non-significant. We conclude that the protein-sparing phase of uncomplicated starvation is associated with decreased whole-body proteolysis, protein synthesis, branched-chain amino acid (BCAA) oxidation, and BCAA clearance. The increase in plasma BCAA levels in starved animals results in part from decreased BCAA catabolism, particularly in heart and skeletal muscles, and from a net release of BCAA by the hepatic tissue.

[Monitoring parameters of energy metabolism in patients with acute abdomen--possible prognostic factors?]

The prognosis of patients treated on account of serious surgical abdominal attacks is influenced apart from the severity of the condition also by failure of the energy metabolism. Some disorders of the milieu intérieur are the result of a deficient energy situation, energy failure participates in the development of organ disorders, failure and death. The cellular energy metabolism can be expressed as the so-called "redox-state" which can be assessed directly by estimating the ratio of ketone substances in arterial blood--AKBR--Arterial Ketone Body Ratio. The objective of the study was to test whether assessment of the AKBR index is possible, what is its importance in clinical practice and to compare its validity in particular with the commonly used scorin system APACHE II and MPI. The authors evaluated 24 patients operated on account of obstruction of the large intestine and 8 patients operated on account of peritonitis of intestinal origin. While evaluation by means of the MPI score helped to assess the prognosis, evaluation by the APACHE II score did not contribute to prediction of the development of the disease. Assessment of AKBR was of prognostic value only in patients who died during treatment.

CONCLUSION

For practical use it is necessary to improve and simplify biochemical examination and scoring systems and learn how to utilize them better.

Leucine and protein metabolism in rats with chronic renal insufficiency

The aim of this study was to evaluate the effect of chronic uremia induced by 5/6 nephrectomy (5/6NX) on changes in protein and branched-chain amino acid (BCAA; valine, leucine and isoleucine) metabolism. The control group consisted of sham operated rats. Twenty eight weeks after surgery the parameters of protein and amino acid metabolism were evaluated using a primed constant intravenous infusion of L-[1-(14)C]leucine. A drop in BCAA levels and a significant increase in urea, creatinine and cholesterol were observed in plasma of all 5/6NX rats. However, severe uremia with acidosis developed only in one third of rats with 5/6NX. In 5/6NX rats with acidosis significant increases in proteolysis, leucine oxidation, leucine oxidized fraction, and leucine clearance were observed in comparison with the control group and rats with 5/6NX without acidosis. In addition, in 5/6NX rats with acidosis a significant decrease in valine concentration in gastrocnemius muscle was found. We conclude that marked activation of proteolysis occurs in severe chronic renal failure and is probably caused by metabolic changes related to acidosis development.

Leucine and protein metabolism after bilateral nephrectomy in rats: the role of hepatic tissue

The aim of this study was to evaluate the effect of acute uremia on changes in leucine and protein metabolism in the whole body and in hepatic tissue. Acute renal insufficiency was induced by bilateral nephrectomy (BNX). Twenty-four hours later, parameters of protein and amino acid metabolism were evaluated in the whole body using primed constant intravenous infusion of L-[1-14C]leucine, and in isolated perfused liver (IPL) using cx-keto[1-14C]isocaproate. The control group consisted of sham-operated rats. BNX induced a marked decrease in proteolysis, protein synthesis, leucine oxidized fraction and leucine clearance. The decrease in protein synthesis was higher than in proteolysis. A significant drop in protein synthesis was observed in muscle, gut, heart and spleen. The study with IPL in BNX animals showed decreased oxidation of ketoisocaproic acid and higher concentrations of the branched-chain amino acids (BCAA) leucine, isoleucine and valine in perfusion solution. We conclude that the cause of rapid depletion of body proteins after BNX is a greater decrease in protein synthesis than in proteolysis associated with an increase in leucine oxidized fraction. The data obtained in the IPL model indicate that BNX causes metabolic changes that enable resynthesis of BCAA from corresponding branched-chain keto acids in liver.

Influence of buthionine sulfoximine, S-adenosylmethionine and glutathione on liver regeneration following partial hepatectomy

This study was designed to evaluate the effect of derangement in methionine metabolism, and the effects of S-adenosylmethionine (SAM) and glutathione (GSH) on liver regeneration. Rats were treated immediately and 6 h after 70% hepatectomy (PH) as follows: (1) SAM, (2) GSH, (3) buthionine sulfoximine (BSO; inhibitor of SAM and GSH synthesis), (4) BSO + SAM, (5) BSO + GSH, and (6) buffer solution (B). The control group consisted of laparotomized animals treated with B. The increase in hepatic DNA synthesis, hepatocyte mitotic activity, and protein synthesis were observed in PH rats while in BSO rats, a delayed onset of liver regeneration was observed. SAM induced an earlier onset of hepatocyte mitotic activity, and reduced the inhibitory effect of BSO. GSH treatment exerted an inhibitory effect on liver regeneration and worsened the negative effect of BSO. It is concluded that derangement in methionine metabolism can impair the development of liver regeneration. The data also demonstrate the favourable effect of SAM and negative effect of GSH.

Effect of hyperammonemia on leucine and protein metabolism in rats

The cause of muscle wasting and decreased plasma levels of branched chain amino acids (BCAA), valine, leucine, and isoleucine in liver cirrhosis is obscure. Here we have evaluated the effect of hyperammonemia. Rats were infused with either an ammonium acetate/bicarbonate mixture, a sodium acetate/bicarbonate mixture, or saline for 320 minutes. The parameters of leucine and protein metabolism were evaluated in the whole body and in several tissues using a primed constant intravenous infusion of L-[1-14C]leucine. Ammonium infusion caused an increase in ammonia and glutamine levels in plasma, a decrease in BCAA and alanine in plasma and skeletal muscle, a significant decrease in whole-body proteolysis and protein synthesis, and an increase in leucine oxidized fraction. A significant decrease in protein synthesis after ammonium infusion was observed in skeletal muscle while a nonsignificant effect was observed in liver, gut, heart, spleen, and kidneys. We conclude that the decrease in plasma BCAA after ammonia infusion is associated with decreased proteolysis and increased leucine oxidized fraction.

Effect of alanyl-glutamine on leucine and protein metabolism in endotoxemic rats

BACKGROUND

Branched-chain amino acids (BCAA; valine, leucine, and isoleucine) have a regulatory effect on protein metabolism and are the main donor for synthesis of alanine and glutamine in the skeletal muscle. This study was performed to investigate whether exogenous alanine or glutamine would affect leucine and protein metabolism in intact and endotoxemic rats.

METHODS

Rats were injected with endotoxin of Salmonella enteritidis or saline. Thirty minutes later, the effects of endotoxemia and L-alanyl-L-glutamine (AG) on leucine and protein metabolism were evaluated using a primed constant infusion of [1-14C]leucine, endotoxin, and AG (200 mg/mL) solution or an infusion of [1-14C]leucine without endotoxin or AG. The specificity of the effect of exogenous alanine and glutamine was evaluated by a single infusion of alanine, glutamine, and glycine in a separate study.

RESULTS

Endotoxin treatment induced more negative net protein balance caused mainly by an increase in whole-body proteolysis. Protein synthesis increased in kidneys, colon, and spleen, while a decrease was observed in skeletal muscle. The impressive effects of AG were the decrease in plasma branched-chain amino acid (BCAA) levels, decrease in leucine oxidized fraction, and improvement of protein balance associated with a decrease in whole-body proteolysis. Similar changes in leucine and protein metabolism were induced by infusion of alanine or glutamine but not by infusion of glycine.

CONCLUSIONS

IV administration of alanine or glutamine improves protein balance and decreases leucine oxidized fraction in postabsorptive state and in endotoxemia. Decreased proteolysis is the main cause of decreased plasma BCAA levels after AG treatment.

[Occult fibrin production during surgery in cyanotic congenital heart defects and extracorporeal circulation]

In 10 patients with complex cyanotic congenital defects detailed coagulation examinations were made at the beginning and end of the extracorporeal circulation after neutralization of heparin by protamine and the results were compared with a control examination, made before general heparinization, after introduction into general anaesthesia. The authors examined the activated period of blood (ACT) by means of testing tubes with a celite activator (Hemochron) as well as the HR-ACT test with a kaolin activator (Medtronic) for comparison of the results. The authors assessed quantitatively plasma levels of heparin, antithrombin III and fibrinopeptide A which is a sensitive indicator of intravascular coagulation. They assessed also the fibrinogen level and total number of thrombocytes in the blood stream. The degree of haemodilution was recorded as well as the temperature at the periods of assessment. The values of both ACT test were within the range of values above 420 secs., evaluated according to the authors protocol as adequate for total heparinization during operations under conditions of extracorporeal circulation. Despite of this heparin levels lower than those recommended in the literature were found, as well as reduced antithrombin III levels during extracorporeal circulation and a rise of fibronopeptide A levels at the end of extracorporeal circulation which suggest latent fibrin production in the patients. Laboratory results were compared with clinical symptoms of post-operation bleeding. In 50% patients after surgery signs of increased haemorrhage in the surgical field and from thoracic drains were observed, in two patients the surgical wound had to be revised. Laboratory tests revealed in two patients thrombocytopenia after surgery, one patient had a prothrombin test reduced below 45% and in one patient there was a significantly reduced fibrinogen level calling for supplementation of this factor. After improvement of the laboratory results and surgical treatment haemostasis returned to normal. All patients survived the operation and were discharged from hospital to domestic treatment.

Leucine metabolism in rat liver after a bolus injection of endotoxin

To evaluate the contribution of hepatic tissue to alterations in the metabolism of proteins and the branched-chain amino acids (BCAA) leucine, isoleucine, and valine in systemic inflammatory response syndrome, we studied the changes of leucine metabolism in isolated perfused liver (IPL) of endotoxin-treated rats. Male albino rats were injected with the endotoxin of Salmonella enteritidis (5 mg x kg(-1)) or saline (control). Four hours later, leucine and ketoisocaproate (KIC) oxidation and incorporation into liver proteins were determined in IPL using the single-pass liver perfusion technique. L-[1-(14)C]leucine and alpha-keto[1-(14)C]isocaproic acid were used as a tracer in two separate experiments. Endotoxin treatment resulted in a decrease of plasma BCAA levels, an increase of leucine oxidation, and a decrease of KIC oxidation by IPL. Leucine incorporation into liver proteins was lower in endotoxin-treated rats, and we did not find measurable incorporation of the labeled carbon of KIC in liver proteins in either group of animals. The sum of individual amino acid concentrations in the effluent perfusate was higher in endotoxin-treated animals, although only leucine and phenylalanine increased significantly. The decrease in KIC oxidation indicates a decreased capacity of hepatic tissue to oxidize branched-chain ketoacids (BCKA). The increase in leucine oxidation by IPL of endotoxin-treated rats indicates an increase in BCAA aminotransferase activity. These changes demonstrate an important response of the body that enables the resynthesis of essential BCAA from their ketoanalogs delivered to the liver from peripheral tissues, particularly muscle.

[Plasma homocysteine levels in patients with indications for cardiac revascularization]

The amino acid homocysteine is a further possible risk factor for the development of atherosclerosis. The authors examined at the First Medical Clinic, Second Medical Faculty Charles University in the course of 1994-1996 59 patients with manifest IHD who were examined by coronarography and because of a major finding were indicated for revascularization surgery. This group was compared with a control group of subjects of equal age without major findings on the coronary circulation. The control group differed from the former group significantly only as regards the triglyceride level which was higher in the former group and the group comprised a larger number of diabetic patients. As regards cholesterol, HDL-cholesterol, uric acid, fibrinogen levels there was no significant difference. The authors found an insignificant difference in homocysteine levels. In the investigated group of patients indicated for revascularization surgery the mean homocysteinaemia was 12.3 mumol/l (sigma 4.3 mumol/l) and in the control group 11.8 mumol/l (sigma 3.8 mumol/l). The mean homocysteine level in the investigated group did not exceed the level of 15 mumol/l reported in the literature as the borderline of normal homocysteine blood levels. The authors did not reveal a statistically significant correlation between homocysteine levels, diabetes mellitus type II and smoking.

[Tissue amino acids in patients with colorectal carcinoma]

Different catabolic conditions have their special characteristics of intracellular biochemical changes. The objective of the presented work is to assess the concentration of free amino acids in muscles of patients with colorectal carcinoma. In a group of 17 patients the free amino acid level was assessed in tissues and plasma. Material was collected on operation by biopsy of the rectus abdominis muscle, the concentration of different amino acids was assessed by the HPLCV method with fluorescent detection. For statistical evaluation the T-test was used. From the results ensues that in patients with colorectal cancer in plasma statistically significantly lower taurine, glutamine, valine, tyrosine levels were found, intracellularly significantly reduced levels of taurine, glutamic acid, methionine and ornithine were recorded. Significantly elevated intracellular levels of valine, isoleucine, leucine, tyrosine and phenylalanine were found. Assessment of the tissue aminoacidogram is the first step when attempting to influence the intracellular amino acid concentration by defined dietetic preparations.

Leucine metabolism in TNF-alpha- and endotoxin-treated rats: contribution of hepatic tissue

The effects of tumor necrosis factor-alpha (TNF-alpha; cachectin) and lipopolysaccharide of Salmonella enteritidis (LPS; endotoxin) on leucine metabolism in rats were evaluated in the whole body using intravenous infusion of L-[1-14C]leucine and in isolated perfused liver (IPL) using the single-pass perfusion technique with alpha-keto[1-14C]isocaproate as a tracer for measurement of ketoisocaproic acid (KIC) oxidation, and the recirculation technique for measurement of hepatic amino acid exchanges. The data obtained in TNF-alpha and LPS groups were compared with those obtained in controls. Both TNF-alpha and LPS treatment induced an increase of whole body leucine turnover, oxidation, and clearance. As the result of a higher increase of leucine oxidation than of incorporation into the pool of body proteins, the fractional oxidation of leucine was increased. The fractional rate of protein synthesis increased significantly in the spleen (both in TNF-alpha and LPS rats), in blood plasma, liver, colon, kidneys, gastrocnemius muscle (in LPS rats), and in lungs (TNF-alpha-treated rats), whereas it decreased in the jejunum (LPS rats). In IPL of TNF-alpha- and LPS-treated rats a decrease of KIC oxidation and higher uptake of branched-chain amino acids (BCAA; valine, leucine, and isoleucine) were observed when compared with control animals. We hypothesize that the negative consequences of increased whole body proteolysis and of increased oxidation of BCAA induced by TNF-alpha and/or LPS are reduced by decreased activity of hepatic branched-chain ketoacid dehydrogenase that can help resupply BCAA to the body.

Nitrogen balance, 3-methylhistidine excretion, and plasma amino acid profile in infants after cardiac operations for congenital heart defects: the effect of early nutritional support

OBJECTIVE

The objective of this study was to evaluate the effect of nutritional support on proteolysis and plasma amino acid profile in infants early after cardiac operations for congenital heart defects.

METHODS

Thirty-seven patients, 2 to 12 months old, were randomized on postoperative day 1 for 24-hour isocaloric metabolic study. Group STANDARD (18 patients) received glucose as the maintenance fluid, and group PN (19 patients) received glucose and crystalloid amino acid solution at a dosage of 0.8 +/- 0.1 gm/kg per day. The nonprotein caloric intake in the two groups was 25 +/- 15 and 33 +/- 9 kcal/kg, respectively (p = not significant).

RESULTS

The nitrogen balance was markedly less negative in group PN than in group STANDARD (-114 +/- 81 vs -244 +/- 86 mg/kg, respectively, p = 0.001). There was a highly significant inverse correlation between the nitrogen balance and urinary 3-methylhistidine excretion in both groups, but the muscle proteolysis was blunted more effectively in patients receiving amino acids. Concentrations of the plasmatic branched-chain amino acids, alanine, glycine, and proline, decreased significantly in group STANDARD but not in group PN on postoperative day 2. Glutamine and threonine levels declined significantly on postoperative day 2 in both groups. Low levels of arginine were observed in our patients before operation and in the early postoperative period. The amino acid concentrations normalized on postoperative day 7 in all patients.

CONCLUSION

Significant proteolysis and hypoaminoacidemia were observed in infants early after cardiac operations. This hypercatabolic response was blunted by parenteral nutritional support.

Leucine metabolism in partially hepatectomized rats

BACKGROUND/AIMS

We hypothesized that the decrease in plasma branched-chain amino acids (i.e. valine, leucine and isoleucine) and the increase in the oxidized leucine fraction demonstrated in cirrhotic rats in our previous study were caused by the reduced liver cell mass. In the present study we have evaluated the influence of the loss of a substantial amount of the hepatic tissue on changes in leucine metabolism.

METHODS

A two-thirds partial hepatectomy (PH) was performed in male Wistar rats, weighing 210-250 g. Sham-operated rats served as controls. Whole-body leucine kinetics and ketoisocaproate oxidation rates in the isolated perfused liver were investigated using continuous infusion of [1-14C]leucine and alpha-keto[1-14C]ketoisocaproate at 0 h, 24 h and 72 h after surgery. All groups were compared by analysis of variance, and differences were considered significant at the p < 0.05 level.

RESULTS

A significant decrease in the sum of branched-chain amino acids in blood plasma was observed at 24 h after PH. The decrease in whole-body leucine utilization in protein synthesis observed at 24 h after PH was associated with a decrease in protein synthesis in the gastrocnemius muscle, in the small intestine and in the liver remnant (although protein synthesis per mg of liver protein was higher than in sham-treated animals). In contrast, the rate of whole-body leucine oxidation increased immediately after PH (PH: 4.5 +/- 0.7 vs. sham: 2.4 +/- 0.4; mumol .100 g b.w.-1.h-1). As a result of the opposite changes in protein synthesis and leucine oxidation, marked increases in oxidized leucine fraction were observed immediately (14.6 +/- 1.5%) and 24 h (15.1 +/- 1.6%) after PH in comparison to the sham-treated rats (7.1 +/- 0.8%). In isolated perfused livers of PH rats, an increase in ketoisocaproate oxidation per liver weight unit was observed at 24 h and 72 h in comparison to the sham group. The loss of liver capacity for ketoisocaproate oxidation was restored at 72 h after PH, although the liver weight did not reach the preoperative value.

CONCLUSIONS

We conclude that the loss of hepatic tissue results in an increase in leucine oxidized fraction that is caused by both a decrease in protein synthesis and an increase in leucine oxidation. Both the liver remnant and the extrahepatic tissues are involved in this response.

Leucine metabolism in rats with cirrhosis

BACKGROUND/AIMS

This study aimed to investigate the pathogenesis of reduced plasma levels of branched-chain amino acids leucine, isoleucine and valine in cirrhosis.

METHODS

Cirrhosis was induced by intragastric administration of 36 doses of carbon tetrachloride in olive oil over a period of 12 weeks. Rats treated with oil alone served as controls. The rates of leucine turnover, clearance, oxidation and incorporation into proteins were evaluated using [1-14C]leucine, [4,5-3H]leucine and alpha-keto[1-14C]isocaproate 3 days after the last intragastric treatment in vivo and in the isolated perfused liver.

RESULTS

In animals with cirrhosis we observed a profound fall in plasma branched-chain amino acid levels and significant decreases in leucine turnover, oxidation and incorporation into tissue proteins. A more pronounced fall in leucine incorporation in proteins resulted in a significant increase in the oxidized leucine fraction in rats with cirrhosis as compared to controls. Leucine clearance was higher in the cirrhosis group. Concomitant to the fall of whole body leucine turnover, decreases of leucine incorporation into protein and of ketoisocaproic acid decarboxylation were observed in the isolated perfused liver of rats with cirrhosis. However, leucine oxidation was increased compared with control rats.

CONCLUSIONS

Our results indicate that the predominant mechanism of the decrease in plasma leucine levels in rats with cirrhosis is an increase in the oxidized leucine fraction associated with a decrease in leucine turnover. An increase in leucine oxidation in the cirrhotic liver is one of the mechanisms involved.

Protein metabolism in cirrhotic rats: effect of dietary restriction

This paper evaluates the role of decreased food intake in protein metabolism in cirrhotic animals by comparing the changes with those observed in pair-fed controls. Rats were injected with [14C]leucine and then divided into 3 groups. Liver cirrhosis was induced in 1 group of rats by repeated intragastric administration of CCl4 in oil over a period of 8 weeks. Control animals were gavaged with oil and either pair-fed or given access to food ad libitum. Three days after the last intragastric dose, rats were injected with [3H]leucine and sacrificed 20 min later. The daily food intake of CCl4 rats declined to 60% of that of the ad libitum controls. Both the pair-fed control group and the cirrhotic group showed decreased body weight gain, and a decline in muscle and intestinal protein degradation. The pair-fed and the cirrhotic groups differed from one another in many metabolic abnormalities. In the cirrhotic group we observed higher levels of serine, asparagine, proline, methionine, tyrosine, phenylalanine, ornithine and histidine, and lower levels of valine, isoleucine and arginine. In these animals higher relative (per kilogram body weight) weights and protein content of the spleen, kidneys and heart were observed. Additionally higher liver weight despite lower protein concentration, as well as lower liver protein degradation and lower skeletal muscle protein synthesis were found.

[Levels of plasma amino acids in normal neonates within the context of their postnatal adaptation]

The authors present values of plasma amino acid concentrations assessed on an automatic analyzer in a group of 12 mature neonates whose early and late post-partum adaptation and subsequent psychosomatic development followed-up to the age of 18 months was normal. The amino acids were assessed at the time of delivery, during the maximal weight loss of the infant after the third day and the last estimation was made before discharge from the maternity hospital when the body weight curves of all infants had a rising trend. None of the infants had neonatal jaundice and all were discharged fully breastfed.