Glucose and fat metabolism during short-term starvation in cirrhosis

Physiological responses to acute fasting: implications for intermittent fasting programs

Intermittent fasting (IF) is a dietary strategy that involves alternating periods of abstention from calorie consumption with periods of ad libitum food intake. There is significant interest in the body of literature describing longitudinal adaptations to IF. Less attention has been given to the acute physiological responses that occur during the fasting durations that are commonly employed by IF practitioners. Thus, the purpose of this review was to examine the physiological responses - including alterations in substrate metabolism, systemic hormones, and autophagy - that occur throughout an acute fast. Literature searches were performed to locate relevant research describing physiological responses to acute fasting and short-term starvation. A single fast demonstrated the ability to alter glucose and lipid metabolism within the initial 24 hours, but variations in protein metabolism appeared to be minimal within this time frame. The ability of an acute fast to elicit significant increases in autophagy is still unknown. The information summarized in this review can be used to help contextualize existing research and better inform development of future IF interventions.

A journey into the world of insect lipid metabolism

Lipid metabolism is fundamental to life. In insects, it is critical, during reproduction, flight, starvation, and diapause. The coordination center for insect lipid metabolism is the fat body, which is analogous to the vertebrate adipose tissue and liver. Fat body contains various different cell types; however, adipocytes and oenocytes are the primary cells related to lipid metabolism. Lipid metabolism starts with the hydrolysis of dietary lipids, absorption of lipid monomers, followed by lipid transport from midgut to the fat body, lipogenesis or lipolysis in the fat body, and lipid transport from fat body to other sites demanding energy. Lipid metabolism is under the control of hormones, transcription factors, secondary messengers and posttranscriptional modifications. Primarily, lipogenesis is under the control of insulin-like peptides that activate lipogenic transcription factors, such as sterol regulatory element-binding proteins, whereas lipolysis is coordinated by the adipokinetic hormone that activates lipolytic transcription factors, such as forkhead box class O and cAMP-response element-binding protein. Calcium is the primary-secondary messenger affecting lipid metabolism and has different outcomes depending on the site of lipogenesis or lipolysis. Phosphorylation is central to lipid metabolism and multiple phosphorylases are involved in lipid accumulation or hydrolysis. Although most of the knowledge of insect lipid metabolism comes from the studies on the model Drosophila; other insects, in particular those with obligatory or facultative diapause, also have great potential to study lipid metabolism. The use of these models would significantly improve our knowledge of insect lipid metabolism.

Blue light-dependent human magnetoreception in geomagnetic food orientation

The Earth's geomagnetic field (GMF) is known to influence magnetoreceptive creatures, from bacteria to mammals as a sensory cue or a physiological modulator, despite it is largely thought that humans cannot sense the GMF. Here, we show that humans sense the GMF to orient their direction toward food in a self-rotatory chair experiment. Starved men, but not women, significantly oriented toward the ambient/modulated magnetic north or east, directions which had been previously food-associated, without any other helpful cues, including sight and sound. The orientation was reproduced under blue light but was abolished under a blindfold or a longer wavelength light (> 500 nm), indicating that blue light is necessary for magnetic orientation. Importantly, inversion of the vertical component of the GMF resulted in orientation toward the magnetic south and blood glucose levels resulting from food appeared to act as a motivator for sensing a magnetic field direction. The results demonstrate that male humans sense GMF in a blue light-dependent manner and suggest that the geomagnetic orientations are mediated by an inclination compass.

Nutritional Needs and Support for Children with Chronic Liver Disease

Malnutrition has become a dangerously common problem in children with chronic liver disease, negatively impacting neurocognitive development and growth. Furthermore, many children with chronic liver disease will eventually require liver transplantation. Thus, this association between malnourishment and chronic liver disease in children becomes increasingly alarming as malnutrition is a predictor of poorer outcomes in liver transplantation and is often associated with increased morbidity and mortality. Malnutrition requires aggressive and appropriate management to correct nutritional deficiencies. A comprehensive review of the literature has found that infants with chronic liver disease (CLD) are particularly susceptible to malnutrition given their low reserves. Children with CLD would benefit from early intervention by a multi-disciplinary team, to try to achieve nutritional rehabilitation as well as to optimize outcomes for liver transplant. This review explains the multifactorial nature of malnutrition in children with chronic liver disease, defines the nutritional needs of these children, and discusses ways to optimize their nutritional.

Free fatty acid as a marker of energy malnutrition in liver cirrhosis

AIM

Protein-energy malnutrition is frequently observed in patients with liver cirrhosis (LC). Non-protein respiratory quotient (npRQ) measured by indirect calorimetry is a good marker to estimate energy malnutrition, and predicts the prognosis of patients with LC. However, measurement of npRQ is limited because of the high cost of indirect calorimetry. Our aim was to find out an alternative marker to npRQ that can be used in the routine clinical setting.

METHODS

One hundred and fifty-six patients with LC were enrolled in this study. Indirect calorimetry and blood examinations were conducted after overnight fasting, and anthropometry was performed by an expert dietician. The correlation between npRQ and other parameters were calculated by simple and multiple regression analysis. Receiver-operator curve (ROC) analysis was used to identify the cut-off value that would best predict the threshold npRQ of 0.85.

RESULTS

Plasma levels of free fatty acid (FFA) was significantly correlated with npRQ value by simple (r = -0.39, P < 0.0001) and multiple regression analysis (t = -2.96, P = 0.0052). Free fatty acid rose in parallel with the increasing disease severity as defined by Child-Pugh classification (P < 0.05). FFA was also correlated with increasing oxidation rate of fat (r = 0.38, P < 0.0001) and decreasing oxidation rate of carbohydrate (r = -0.39, P < 0.0001). The cut-off value of FFA to predict npRQ = 0.85 was 660 μEq/L by ROC analysis.

CONCLUSION

FFA is a useful alternative marker to represent npRQ in patients with LC.

Sexual dimorphism in the effects of exercise on metabolism of lipids to support resting metabolism

Exercise training is generally a healthful activity and an effective intervention for reducing the risk of numerous chronic diseases including cardiovascular disease and diabetes. This is likely both a result of prevention of weight gain over time and direct effects of exercise on metabolism of lipids and the other macronutrient classes. Importantly, a single bout of exercise can alter lipid metabolism and metabolic rate for hours and even into the day following exercise, so individuals who regularly exercise, even if not performed every single day, overall could experience a substantial change in their resting metabolism that would reduce risk for metabolic diseases. However, resting metabolism does not respond similarly in all individuals to exercise participation, and indeed gender or sex is a major determinant of the response of resting lipid metabolism to prior exercise. In order to fully appreciate the metabolic effects and health benefits of exercise, the differences between men and women must be considered. In this article, the differences in the effects of exercise on resting metabolic rate, fuel selection after exercise, as well as the shuttling of triglyceride and fatty acids between tissues are discussed. Furthermore, concepts related to sex differences in the precision of homeostatic control and sex differences in the integration of metabolism between various organs are considered.

DNA microarray analysis identified molecular pathways mediating the effects of supplementation of branched-chain amino acids on CCl4-induced cirrhosis in rats

SCOPE

This study addresses the effects of branched-chain amino acids (BCAA) on global gene expression in liver and skeletal muscle and the molecular mechanisms underlying the improvement in liver cirrhosis using DNA microarray analysis combined with RNase protection assay.

METHODS AND RESULTS

Male Wistar rats administered carbon tetrachloride (CCl(4) ) repeatedly for 19 weeks as a decompensated cirrhosis model were thereafter given BCAA-enriched diet (AL) or normal diet (LC) for 5 weeks. The control-diet rats without CCl(4) administration were used as a normal control group. Gene expression in AL was reversed by twofold greater than in LC in the microarray were selected to elucidate the improvements in nutritional and metabolic disorders. Downregulation of fatty acid translocase (FAT)/Cd36, glutamine synthetase, and pyruvate dehydrogenase kinase isoenzyme 4 is believed to promote lower uptake of fatty acids, lower ammonia incorporation, and higher uptake of glucose, and thus to provide an energy source without using BCAA. Ultimately, the catabolism of BCAA and skeletal muscle protein would be slowed, maintaining BCAA concentrations in blood.

CONCLUSION

We established, for the first time, the regulatory gene pathways of processes involved in hepatic fibrosis and energy metabolism (hypoalbuminemia, hyperammonemia, and carbohydrate catabolism, and their relationships) under BCAA supplementation.

Impact of splenectomy in patients with liver cirrhosis: Results from 18 patients in a single center experience

AIM

  With the recent advances in medical or surgical treatments in chronic hepatic disorders, the indications for splenectomy in hepatic disorders have greatly expanded. We performed splenectomy for cirrhotic patients and investigated the effects of splenectomy on hepatic functional reserve and nutrition metabolism.

METHODS

  Eighteen patients (Child-Pugh B/C: 12/6; Child-Pugh A: excluded) who underwent splenectomy at our institute between 2005 and 2008 were enrolled. Twelve patients (67%) had hepatocellular carcinoma (HCC), eight of whom met the Milan criteria.

RESULTS

  Overall survival rate was 83.3% at 1 year and 62.7% at 2 years. The survival rate of six patients with liver cirrhosis classified a Child-Pugh C was 80.0% at 1 year and 60.0% at 2 years. Three patients underwent hepatic resection and nine patients received ablation therapy against hepatocelluar carcinoma. Portal pressure decreased after splenectomy in most patients (mean decrease, 4.7 mmHg). Four weeks after the operation, the markers of hepatic functional reserve, indocyanine green retention rate at 15 min (ICGR15) and Technetium-99m-galactosyl human serum albumin value ((99m)Tc-GSA), improved from 38.5% to 35.1% and from 0.773 to 0.788 (LHL15), respectively. The non-protein respiratory quotient (npRQ) did not change in short period after the operation. Other outcomes, including liver function test in cirrhotic patients with long-term (1 year) follow-up after splenectomy (n = 7), did not improve significantly. Post-operative complications included portal thrombus (n = 2), ascites (n = 2) were observed in six patients (33%).

CONCLUSION

  Splenectomy improved hepatic functional reserve and nutritional metabolism in some cases. However, the long-term outcomes should still be evaluated.

Health maintenance issues in cirrhosis

Caring for patients with cirrhosis requires special consideration. The role of the hepatologist is to assist the primary care physician in caring for such patients. This involves an active role in immunizations, lifestyle modifications, and providing instructions on when to go to the emergency room (ER). There are also specific recommendations geared toward the patient with cirrhosis relating to slowing down the disease process, maintaining quality of life, and improving survival.

Glucoregulation is more precise in women than in men during postexercise recovery

BACKGROUND

The regulation of glycemia is challenged in healthy men and women after exercise bouts of substantial energy expenditure.

OBJECTIVE

We determined rates of glucose appearance (Ra), disappearance (Rd), and metabolic clearance (MCR) before, during, and after isoenergetic moderate and hard-intensity exercise.

DESIGN

Ten men and 8 women received primed-continuous infusion of [6,6-(2)H(2)]glucose tracer to measure glucose kinetics. Participants were studied under 3 different conditions with diet unchanged between trials: 1) before, during, and 3 h after 90 min of exercise at 45% of peak oxygen consumption (VO(2)peak; E45); 2) before, during, and 3 h after 60 min of exercise at 65% VO(2)peak (E65), and 3) in a time-matched sedentary control trial.

RESULTS

In men and women, Ra, Rd, and MCR increased above the control trial during exercise and were higher in E65 than in E45 (P < 0.05). Average Ra, Rd, and MCR remained elevated above the control over 3 h of postexercise recovery in men after exercise in E45 and E65 (P < 0.05), and blood glucose concentrations were depressed below the control during recovery (P < 0.05). Glucose concentrations were not depressed in women during 3 h of postexercise recovery, and in contrast with that in men, average Ra and Rd did not remain significantly elevated during postexercise recovery in women, although MCR did remain elevated in E65 (P < 0.05).

CONCLUSIONS

After exercise bouts, women are better able to maintain glucose concentrations at sedentary control levels, thus not requiring the counter-regulation of glucose production that is seen in men and requiring less accentuation of lipid metabolism.

Lipolysis and fatty acid metabolism in men and women during the postexercise recovery period

We sought to determine whether lipolysis, fatty acid (FA) mobilization, and plasma FA oxidation would remain elevated for hours following isoenergetic exercise bouts of different intensities. Ten men and eight women received a primed-continuous infusion of [1,1,2,3,3-(2)H(5)]glycerol and continuous infusion of [1-(13)C]palmitate to measure glycerol and plasma FA kinetics. On Day 1 (D1), participants were studied under one of three different conditions, assigned in random order: (1) before, during and 3 h after 90 min of exercise at 45% V(O2)peak (E45), (2) before, during and 3 h after 60 min of exercise at 65% V(O2)peak (E65), and (3) in a time-matched sedentary control trial (C). For each condition, participants were studied by indirect calorimetry the following morning as well (D2). Rate of appearance (Ra) of glycerol (Ra(GL)) increased above C during exercise in men and women (P < 0.05), was higher in E45 than E65 in men (P < 0.05), and was not different between exercise intensities in women. During 3 h of postexercise recovery, Ra(GL) remained significantly elevated in men (P < 0.05), but not women. FA Ra (Ra(FA)) increased during exercise in men and women and was higher in E45 than E65 (P < 0.05), and remained elevated during 3 h of postexercise recovery in both sexes (P < 0.05), but with a greater relative increase in men than women (P < 0.05). Plasma FA oxidation (Rox) increased during exercise with no difference between intensities, and it remained elevated during 3 h of postexercise recovery in both sexes (P < 0.05). Total lipid oxidation (Lox) was elevated in both sexes (P < 0.05), but more in men during 3 h of postexercise recovery on D1 (P < 0.05) and remained elevated on D2 in men (P < 0.05), but not in women. There were no differences between E45 and E65 for postexercise energy substrate turnover or oxidation in men and women as energy expenditure of exercise (EEE) was matched between bouts. We conclude that the impact of exercise upon lipid metabolism persists into recovery, but that women depend more on lipid during exercise whereas, during recovery, lipid metabolism is accentuated to a greater extent in men.

Restoration of the glycogen-forming function of hepatocytes in rats with liver cirrhosis is facilitated by a high-carbohydrate diet

Using cytofluorimetric and biochemical methods, the content of glycogen and its labile and stable fractions, as well as activities of glucose-6-phosphatase (EC 3.1.3.9), glycogen phosphorylase (EC 2.4.1.1) and glycogen synthase (EC 2.4.1.11) were determined in the rat liver for 6 months after chronic poisoning of the animals with CCl4 and then at 1, 3, and 6 months after the end of the poisoning. One group of rats was given a standard diet, the other, a high-carbohydrate diet. The 6-month long chronic intoxication with CCl4 was shown to produce development of typical liver cirrhosis characterized by a 2·8-fold increase in the total glycogen content in hepatocytes as compared with normal cells, by a fall in the glycogen labile fraction (from 85 to 53 % of the total glycogen) as well as by decreases in the activities of glycogen phosphorylase and glucose-6-phosphatase by 25 and 82% respectively. The structural rehabilitation occurred faster and more completely at the cellular level than at the tissue level. Functional variables of the cirrhotic liver tissue also recovered, after cessation of poisoning, faster and more completely than the liver structure at the tissue level: glycogen levels in hepatocytes fell dramatically, the labile: stable glycogen fraction ratio recovered completely, and the activity of glycogen phosphorylase rose to the level characteristic of the normal liver. Use of the high-carbohydrate diet promoted a somewhat faster and more complete recovery of hepatic structure and function.

FFAs are not involved in regulation of gluconeogenesis and glycogenolysis in adults with uncomplicated P. falciparum malaria

In normal subjects, elevation of plasma free fatty acid (FFA) levels stimulates gluconeogenesis (GNG) and inhibits glycogenolysis (GLY). In adults with uncomplicated Plasmodium falciparum malaria, GNG is increased and GLY decreased. To test the hypothesis that FFAs are regulators of GNG and GLY in uncomplicated falciparum malaria, we investigated the effect of inhibition of lipolysis by acipimox in 12 patients with uncomplicated falciparum malaria. Six of them were given acipimox, and six served as controls. Also as controls, six matched healthy subjects were studied on two occasions with and without acipimox. After 16 h of fasting, glucose production and GNG were significantly higher in the malaria patients compared with the healthy controls (P = 0.003 and < 0.0001, respectively), whereas GLY was significantly lower (P < 0.001), together with elevated plasma concentrations of cortisol and glucagon. During the study, glucose production in patients declined over time (P < 0.0001), without a statistically significant difference between the acipimox-treated and untreated patients. In controls, however, with acipimox the decline was less outspoken compared with nontreated controls (P = 0.005). GNG was unchanged over time in patients as well as in healthy controls, and no influence of acipimox was found. In patients, GLY declined over time (P < 0.001), without a difference between acipimox-treated and untreated patients. In contrast, in controls treated with acipimox, no change over time was found, which was statistically different from the decline in untreated controls (P = 0.002). In conclusion, in falciparum malaria, FFAs are not involved in regulation of glucose production, nor of GNG or GLY.

IGF1 gene transfer into skeletal muscle using recombinant adeno-associated virus in a rat model of liver cirrhosis

Systemic administration of recombinant IGF1 at low levels has been shown to improve hepatic function, nutritional status and testicular atrophy in rats with CCl4-induced cirrhosis. We have developed a recombinant adeno-associated (rAAV) viral vector containing the cDNA for rat IGF1 and confirmed the expression of IGF1 after intramuscular injection of this vector in a rat model of liver cirrhosis. Although weight of injected muscles was significantly increased in rats with mild cirrhosis, this was not the case in rats with advanced, de-compensated cirrhosis. Furthermore, we found no significant amelioration of liver damage in treated rats at any stage of liver cirrhosis. Our results suggest that IGF1 gene transfer into muscle results in a local effect, at least at the vector dose employed here.

Altered intestinal transport of amino acids in cirrhotic rats: the effect of insulin-like growth factor-I

The intestine is an important target organ for insulin-like growth factor-I (IGF-I), an anabolic hormone synthesized in the liver upon growth hormone (GH) stimulation. Levels of IGF-I are reduced in cirrhosis, and altered GH/IGF-I axis may contribute to malnutrition in cirrhotic patients. Our aim was to study Na(+)-dependent jejunal transport of amino acids (L-leucine, L-proline, L-glutamic acid, and L-cysteine) in cirrhotic rats and to analyze the effect of IGF-I on this function. IGF-I or saline was administered for 2 wk to rats with CCl(4)-induced cirrhosis and saline was administered to healthy control rats. Transport of amino acids was assessed in brush-border membrane vesicles (BBMV) using (14)C- or (35)S-labeled amino acids, and the kinetic constants V(max) and K(t) were determined. Na(+)-independent uptake of L-leucine, L-proline, L-glutamic acid, and L-cysteine by BBMV was similar in all groups. Na(+)-dependent uptake of all four amino acids was significantly diminished in cirrhotic rats compared with both controls and IGF-I-treated cirrhotic rats. The latter two groups exhibited similar V(max) and K(t), whereas untreated cirrhotic rats had reduced V(max) and increased K(t) compared with normal controls and IGF-I-treated cirrhotic animals. In conclusion, the transport of all four tested amino acids by BBMV is impaired in cirrhotic rats, and low doses of IGF-I can correct this defect.

Lipolysis and lipid oxidation in cirrhosis and after liver transplantation

On the basis of the finding that plasma glycerol concentration is not controlled by clearance in healthy humans, it has been proposed that elevated plasma free fatty acid (FFA) and glycerol concentrations in cirrhotic subjects are caused by accelerated lipolysis. This proposal has not been validated. We infused 10 volunteers, 10 cirrhotic subjects, and 10 patients after orthotopic liver transplantation (OLT) with [1-(13)C]palmitate and [(2)H(5)]glycerol to compare fluxes (R(a)) and FFA oxidation. Cirrhotic subjects had higher plasma palmitate (52%) and glycerol (33%) concentrations than controls. Palmitate R(a) was faster (1.45+/-0.18 vs. 0.85+/-0.17 micromol x kg(-1) x min(-1)) but glycerol R(a) and clearance slower (1.20+/-0.09 vs. 1.90+/-0.24 micromol x kg(-1) x min(-1) and 21.2+/-1.2 vs. 44.7+/- 4.9 ml x kg(-) x h(-1), respectively) than in controls. After OLT, plasma palmitate and glycerol concentrations and palmitate R(a) did not differ, but glycerol R(a) (1.16+/-0.11 micromol x kg(-1) x min(-1)) and clearance (26.7+/-2.4 ml x kg(-1) x h(-1)) were slower than in controls. We conclude that 1) impaired reesterification, not accelerated lipolysis, elevates FFA in cirrhotic subjects; 2) normalized FFA after OLT masks impaired reesterification; and 3) plasma glycerol concentration poorly reflects lipolytic rate in cirrhosis and after OLT.

Substrate metabolism during different exercise intensities in endurance-trained women

We have studied eight endurance-trained women at rest and during exercise at 25, 65, and 85% of maximal oxygen uptake. The rate of appearance (R(a)) of free fatty acids (FFA) was determined by infusion of [(2)H(2)]palmitate, and fat oxidation rates were determined by indirect calorimetry. Glucose kinetics were assessed with [6,6-(2)H(2)]glucose. Glucose R(a) increased in relation to exercise intensity. In contrast, whereas FFA R(a) was significantly increased to the same extent in low- and moderate-intensity exercise, during high-intensity exercise, FFA R(a) was reduced compared with the other exercise values. Carbohydrate oxidation increased progressively with exercise intensity, whereas the highest rate of fat oxidation was during exercise at 65% of maximal oxygen uptake. After correction for differences in lean body mass, there were no differences between these results and previously reported data in endurance-trained men studied under the same conditions, except for slight differences in glucose metabolism during low-intensity exercise (Romijn JA, Coyle EF, Sidossis LS, Gastaldelli A, Horowitz JF, Endert E, and Wolfe RR. Am J Physiol Endocrinol Metab 265: E380-E391, 1993). We conclude that the patterns of changes in substrate kinetics during moderate- and high-intensity exercise are similar in trained men and women.

Daily pattern of energy metabolism in cirrhosis

The daily pattern of energy expenditure and the oxidation rates of carbohydrates, fats, and protein were evaluated by indirect calorimetry in 18 control subjects (Group 1) and 34 cirrhotic patients who were divided into Groups 2a and 2b showing indocyanin green retention rates at 15 min of <30% and 30% or more, respectively. The ratio of resting energy expenditure to basal energy expenditure (%REE) was higher in the cirrhotic patients than in the controls at 8:30 AM and 2:30 PM. The oxidation rates of carbohydrates and fats under fasting conditions in Group 2b patients were respectively lower, and higher than in Group 1 and 2a patients. After the subjects ate, glucose became the substrate preferentially metabolized, and the proportion of fat metabolized was reduced from 82.9+/-5.1% to 43.9+/-21.9% and from 70.7+/-14.1% to 46.8+/-13.9% in the patients with advanced and less advanced cirrhosis, respectively, and from 59.4+/-27.2% to 48.4+/-18.5% in the controls. The fasting concentrations of non-esterified fatty acids in Group 2b were also significantly higher than those in the Group 1 and Group 2a patients. After eating, these concentrations fell and reached similar levels in the patients and controls. These data indicated that the patients with cirrhosis developed the catabolic state of starvation in the morning because of a lack of glycogen stores. Therefore, frequent meal supplementation to prevent early-onset starvation and energy deficiency may be advisable in such patients to maintain a well-nourished condition.

Assessment of body composition using dual energy x-ray absorptiometry in patients with liver cirrhosis: comparison with anthropometry

OBJECTIVES

The aim of this study was to evaluate changes of body composition in cirrhotic patients. Dual energy x-ray absorptiometry (DEXA) and anthropometry were used, and the values obtained were compared.

METHODS

Mid-arm fat and muscle areas were calculated by anthropometry in 66 cirrhotic patients and 94 healthy controls. In 37 of the cirrhotic patients and 39 of the controls, fat mass, lean soft tissue mass and bone mineral contents were measured with DEXA.

RESULTS

The number of cirrhotic patients with measured values below the fifth percentile of normal controls was 21 (31.8%) by mid-arm fat area, six (9.1%) by mid-arm muscle area, 15 (40.5%) by fat mass and 0 (0%) by lean soft tissue mass. The fat mass in cirrhotic patients was less than in controls, whereas lean soft tissue mass and bone mineral content were not different. Fat depletion was severe in Child-class C patients and with severe ascites. Mid-arm fat area and fat mass showed close correlation (r = 0.85, p < 0.01), but mid-arm muscle area and lean soft tissue mass showed poor correlation (r = 0.32, p < 0.05).

CONCLUSION

Cirrhotic patients showed lower fat component, with preserved lean soft tissue mass and bone mineral content. In clinical practice, the measurement of mid-arm fat area was useful for the assessment of fat mass.

Contributions of net hepatic glycogenolysis and gluconeogenesis to glucose production in cirrhosis

Net hepatic glycogenolysis and gluconeogenesis were examined in normal (n = 4) and cirrhotic (n = 8) subjects using two independent methods [13C nuclear magnetic resonance spectroscopy (NMR) and a 2H2O method]. Rates of net hepatic glycogenolysis were calculated by the change in hepatic glycogen content before ( approximately 11:00 PM) and after ( approximately 7:00 AM) an overnight fast using 13C NMR and magnetic resonance imaging. Gluconeogenesis was calculated as the difference between the rates of glucose production determined with an infusion of [6,6-2H2]glucose and net hepatic glycogenolysis. In addition, the contribution of gluconeogenesis to glucose production was determined by the 2H enrichment in C-5/C-2 of blood glucose after intake of 2H2O (5 ml/kg body water). Plasma levels of total and free insulin-like growth factor I (IGF-I) and IGF-I binding proteins-1 and -3 were significantly decreased in the cirrhotic subjects (P < 0.01 vs. controls). Postprandial hepatic glycogen concentrations were 34% lower in the cirrhotic subjects (P = 0.007). Rates of glucose production were similar between the cirrhotic and healthy subjects [9.0 +/- 0.9 and 10.0 +/- 0.8 micromol. kg body wt-1. min-1, respectively]. Net hepatic glycogenolysis was 3.5-fold lower in the cirrhotic subjects (P = 0.01) and accounted for only 13 +/- 6% of glucose production compared with 40 +/- 10% (P = 0.03) in the control subjects. Gluconeogenesis was markedly increased in the cirrhotic subjects and accounted for 87 +/- 6% of glucose production vs. controls: 60 +/- 10% (P = 0.03). Gluconeogenesis in the cirrhotic subjects, as determined from the 2H enrichment in glucose C-5/C-2, was also increased and accounted for 68 +/- 3% of glucose production compared with 54 +/- 2% (P = 0.02) in the control subjects. In conclusion, cirrhotic subjects have increased rates of gluconeogenesis and decreased rates of net hepatic glycogenolysis compared with control subjects. These alterations are likely important contributing factors to their altered carbohydrate metabolism.

Quantification of gluconeogenesis in cirrhosis: response to glucagon

BACKGROUND & AIMS

Accelerated starvation and early recruitment of alternate fuels in cirrhosis have been attributed to reduced availability of hepatic glycogen. The aim of this study was to measure gluconeogenesis (as a marker of protein oxidation) in relation to total glucose production and glucagon-stimulated glycogenolysis.

METHODS

Glucose and urea production, gluconeogenesis, and glycogenolysis were calculated using stable isotope methods before and during glucagon infusion (3 ng. kg-1. min-1) in 5 cirrhotic patients and 5 matched controls before and after glycogen repletion.

RESULTS

In the basal state, cirrhotic patients had a normal rate of glucose production, but the contribution of gluconeogenesis was increased (74.3% +/- 4.1% vs. 55. 6% +/- 12.1%; P < 0.005). Glycogen repletion normalized the rate of gluconeogenesis. The glycemic response to glucagon (3 ng. kg-1. min-1) was blunted in cirrhotic patients because of a lower rate of glycogenolysis (0.63 +/- 0.23 vs. 1.22 +/- 0.23 mg. kg-1. min-1; P < 0.01) and was not affected by glycogen repletion. Despite increased gluconeogenesis, the simultaneously measured rate of urea synthesis was lower in cirrhotic patients (3.11 +/- 1.02 vs. 5.0 +/- 1.0 mg/kg; P < 0.05).

CONCLUSIONS

These data show that in cirrhosis, glucose production is sustained by an increased rate of gluconeogenesis. The hepatic resistance to glucagon action is not caused by reduced glycogen stores.

Defective nonoxidative leucine degradation and endogenous leucine flux in cirrhosis during an amino acid infusion

The metabolic fate of leucine's first and second carbon may be different depending on the tissue in which leucine is metabolized, as well as the prevailing hormonal milieu of that tissue. However, previous studies of leucine kinetics in humans have used only leucine labeled (as tracer) at the first carbon position. Because cirrhosis is associated with factors (such as insulin resistance and altered fuel substrate utilization) that may influence how leucine is degraded, the kinetics of leucine's first and second carbon using a simultaneous infusion of [1-14C] leucine and [2-13C] leucine were studied in the postabsorptive state and during an amino acid infusion in 6 stable cirrhotic patients and 6 matched controls. The data were normalized for different body compartments that were quantified from the dilution of H2 [180] and bromide. The body cell mass, but not body weight or fat-free body mass, was decreased in cirrhosis (P < .001). In response to the amino acid infusion, total leucine appearance from proteolysis and leucine's incorporation into protein increased significantly in both groups, but were higher in cirrhotic patients. Endogenous protein breakdown decreased in normals but remained unchanged in cirrhosis. These alterations in leucine metabolism became more prominent when data were expressed based on the body cell mass rather than on body weight. The oxidation of leucine's first carbon (C1) was decreased in cirrhosis, but the oxidation of leucine's second carbon (C2) did not differ between groups during both the postabsorptive period and the amino acid infusion, while nonoxidative leucine degradation [the difference between the oxidation of leucine's (C1) and (C2)] was also decreased in cirrhosis. In addition, there was a positive correlation between nonoxidative leucine degradation (which represents leucine incorporation into fat), and the respiratory quotient obtained from indirect calorimetry (r = .87; P < .001). These data suggest that the extent of leucine carbon oxidation is dependent on whether fat or carbohydrate is the prevailing fuel substrate. In addition, cirrhotic patients have decreased nonoxidative leucine degradation and are unable to suppress endogenous protein breakdown normally in response to amino acid administration. These abnormalities may contribute to the diminished fat stores and body cell mass commonly observed in cirrhosis.

Daily energy and substrate metabolism in patients with cirrhosis

Twenty-four-hour energy expenditure (EE) and substrate oxidation (respiratory chamber), and whole-body glucose uptake and oxidation rates (euglycemic hyperinsulinemic clamp [EHC] and indirect calorimetry) were measured in 10 male patients with posthepatitis, Child B cirrhosis, and 8 healthy male controls matched for age, body size, and body composition. Twenty-four-hour EE was higher in cirrhotic patients than in controls (8,567 +/- 764 vs. 6,825 +/- 507 kJ/d; P < .001). Resting energy expenditure (REE) was also higher in cirrhotic patients than in controls (7,881 +/- 1,125 vs. 5,868 +/- 489 kJ/d; P < .01). Twenty-four-hour respiratory quotient (RQ) (trend) and fasting RQ (0.76 +/- 0.05 vs. 0.82 +/- 0.04; P < .05) were lower in cirrhotic patients than in controls, reflecting higher lipid oxidation rates in the former group. Whole-body glucose uptake was markedly reduced in cirrhotic patients when compared with controls (22.4 +/- 3.2 vs. 44.5 +/- 7.6 mmol/kg/min; P < .001). Carbohydrate oxidation rates, computed during the last 40 minutes of the clamp, were 8.5 +/- 1.1 mmol/kg/min in cirrhotic patients and 22.6 +/- 6.1 mmol/kg/min in controls (P < .001). Nonoxidative glucose disposal was 13.9 +/- 2.5 mmol/kg/min in cirrhotic patients and 22.0 +/- 5.5 mmol/kg/min in normal controls (P < .01). In conclusion, our data indicate that patients with Child B cirrhosis who still maintain a nutritional status (i.e., body composition) comparable with healthy controls are characterized by a cluster of metabolic defects that include hypermetabolism, increased lipid utilization, and insulin resistance. This suggests that the above metabolic syndrome precedes and probably leads to malnutrition in the natural history of the liver disease. In fact, in spite of the absence of a significant difference in caloric intake between cirrhotic patients and normal controls, the elevated 24-hour EE might allow for a relevant weight loss in cirrhotic patients, because, with time, the differences may be cumulative. However, whether this hypermetabolism can lead to a real weight loss remains to be evaluated in a longitudinal study.

Osteopenia in rats with liver cirrhosis: beneficial effects of IGF-I treatment

BACKGROUND/AIMS

Liver cirrhosis is associated with osteopenia and also with low levels of IGF-I. This hormone has been reported to stimulate bone formation in states of undernutrition and low bone turnover. Our aims were to evaluate whether osteopenia develops in male Wistar rats with CCl4-induced cirrhosis and whether IGF-I is effective in the restoration of bone mass in these animals.

METHODS

Cirrhotic rats were distributed into two groups: group CI (n = 12) which received placebo and group CI + IGF (n = 12) which was treated with human recombinant IGF-I (2 microg/100 g bw/day, s.c., 21 days). Twelve normal animals which received placebo constituted the control group. On the 22nd day, the animals were sacrificed, and bone parameters were analyzed in femur and/or tibia.

RESULTS

Posterior-anterior and latero-medial diameters were similar in all groups. Also, no significant differences were observed in bone contents of calcium, total proteins, collagen and hydroxyapatite in CI rats as compared with controls. However, CI rats showed significant reductions in bone weight (-13.5%, p < 0.001), total bone density (-9.28%, p < 0.001), and increased perimedullar bone resorption and urinary levels of deoxypyridinoline (a marker of bone resorption). In CI + IGF rats these parameters improved significantly as compared with CI animals.

CONCLUSIONS

Osteopenia characterized by loss of bone mass and preserved bone composition is found in rats with CCl4-induced cirrhosis. This bone disorder is partially corrected by treatment with low doses of IGF-I. Since osteoporosis seems to be the predominant form of osteopenia in patients with cirrhosis, IGF-I should be considered as a possible therapy for this disorder.

Oxygen metabolism during liver transplantation: the effect of dichloroacetate

Dichloroacetate (DCA) stimulates pyruvate dehydrogenase (PDH), accelerating recovery of the postischemic heart. Because DCA also stimulates hepatic PDH, it may facilitate graft recovery during liver transplantation (OLT). Hepatic removal and replacement during OLT produce major changes in O2 consumption (VO2), and return of baseline VO2 has been used to index early graft function. We examined the effect of DCA on O2 metabolism during OLT. Forty patients received DCA 80 mg/kg intravenously in divided doses, and 40 served as controls. Serial measurements were made for body temperature, hemodynamics, O2 metabolic indices, and plasma substrate and hormonal concentrations. Oxygen delivery (DO2I) and consumption (VO2I) indices were calculated. Patients exhibited stable hemodynamics, with similar fluid and blood product requirements. Compared with the dissection stage, DO2I and VO2I were decreased during the anhepatic stage (31% and 36%, respectively), then returned to dissection stage values soon after portal vein unclamping. Temperature decreased during the anhepatic stage and returned toward dissection stage value after graft perfusion. DCA reduced lactic acidosis and NaHCO3 use but did not alter hemodynamics or measures of O2 metabolism or body temperature. VO2 is decreased during the anhepatic stage largely due to loss of hepatic metabolism. Restoration of VO2 by 30 min after portal vein unclamping reflects rapid recovery of O2 metabolism by the graft liver, but DCA does not accelerate recovery of VO2. DCA does not seem to facilitate early graft hepatic function as indexed by VO2.

IMPLICATIONS

We evaluated whether dichloroacetate, which stimulates pyruvate dehydrogenase, can accelerate recovery of graft liver hepatic function during liver transplantation, as indexed by oxygen consumption. We found that despite evidence that it activated pyruvate dehydrogenase, dichloroacetate did not affect recovery of transplanted liver function.

Differential effects of enzyme supplementation therapy on manifestations of type 1 Gaucher disease

BACKGROUND

In type 1 Gaucher disease (GD), the accumulation of glucocerebroside in macrophages, caused by deficient activity of glucocerebrosidase, results in a variety of disease manifestations. In addition to the characteristic features of hepatosplenomegaly, cytopenia, and bone abnormalities, resting energy expenditure (REE) and glucose production are increased. In this study the effects of enzyme supplementation therapy on metabolic parameters in relation to other disease manifestations in type 1 GD patients are investigated.

PATIENTS AND METHODS

In 12 adult type 1 GD patients, measurements of REE (by indirect calorimetry), liver and spleen volume (by spiral computerized axial tomography [CT]) and hemoglobin and platelet count were obtained before and after 6 months of alglucerase therapy (15 U/kg per month). In 7 of the 12 patients hepatic glucose production was measured by infusing 3-3H glucose. For comparison, REE and glucose metabolism were studied in 7 weight- and age-matched healthy subjects.

RESULTS

REE and glucose production were increased in GD patients as compared with controls (REE: 29.8 kcal/kg/24 h +/- 3.6 and 23.1 +/- 2.3 kcal/kg/24 h, respectively, P < 0.05; glucose production: 14.00 mumol/kg/min +/- 0.51 and 10.77 mumol/kg/min +/- 0.26, respectively, P < 0.03). There were no differences in plasma glucose concentrations. Whereas the elevated REE decreased after 6 months of alglucerase therapy from 129% to 120% of predicted values (P < 0.01), the increase in hepatic glucose production did not change. An increase in weight occurred after 6 months of treatment (1.7 +/- 0.8 kg, P < 0.001), which was accounted for by an increase in fat mass of 1.6 +/- 1.5 kg (P < 0.02). Hemoglobin levels increased from 11.2 mg/dL to 12.1 mg/dL (P = 0.05) and platelet counts rose from 84 x 10(9)/L to 113 x 10(9)/L (P < 0.05). Although liver and spleen volumes decreased by approximately 10% and approximately 20%, respectively, there was no correlation between the decrease in organ volumes and the decrease in REE.

CONCLUSIONS

Treatment with alglucerase improves hypermetabolism and organomegaly in GD, whereas the increase in glucose production persists. Therefore, the dose-response effects of alglucerase are variable for the different manifestations of type 1 GD.

Effects of extra-carbohydrate supplementation in the late evening on energy expenditure and substrate oxidation in patients with liver cirrhosis

BACKGROUND

The purpose of this study was to demonstrate the effects of extra-carbohydrate supplementation before bedtime on energy metabolism and substrate oxidation in patients with liver cirrhosis.

METHODS

Sixteen cirrhotic patients and eight control subjects were included in this study. To compare the effect of energy metabolism and substrate oxidation with or without a bedtime snack, indirect calorimetry was assessed at 7 to 8 AM after overnight fasting, following either dinner (6 PM) or a bedtime snack (11 PM) the evening before. The bedtime snack contained about 50 g of carbohydrate. The energy expenditure and substrate oxidation were calculated from the indirect calorimetry measurement and 24-hour urinary nitrogen excretion.

RESULTS

In those who fasted since dinner, the respiratory quotient (RQ) was significantly lower in cirrhotic patients than in control subjects. Also, the energy utilized by cirrhotic patients was derived primarily from fat oxidation (58%), whereas the main energy source for controls was carbohydrate (55%). An extra-carbohydrate supplement before bedtime did not influence the indirect calorimetry measurement in the controls, but there were significant increases in both RQ and carbon dioxide production (Vco2) in cirrhotic patients. The extra-carbohydrate supplementation did not significantly change the absolute resting energy expenditure utilization in control subjects; however, the utilization of carbohydrate significantly increased with a decrease in fat and protein oxidation in the cirrhotic patients.

CONCLUSIONS

These preliminary data suggest that extra-carbohydrate supplementation before bedtime can shorten nocturnal fasting with a more economic fuel utilization and effectively diminish fat and protein oxidation in cirrhotic patients.

Low doses of insulin-like growth factor-I improve nitrogen retention and food efficiency in rats with early cirrhosis

BACKGROUND/AIMS

In order to ascertain whether malnutrition is an early-onset feature of liver cirrhosis and whether the anabolic hormone insulin-like growth factor I (IGF-I) could be useful in the treatment of this complication, we analyzed the nutritional alterations present in rats with early-stage liver cirrhosis and the effects of IGF-I on nutritional parameters in these animals.

METHODS

After a 24 h fast, a 15N-enriched diet was administered for 5 days to normal control rats and to cirrhotic rats receiving subcutaneous injections of vehicle (Group 1) or IGF-I, 2 micrograms.100 g bw-1.day-1, (Group 2) during the 5 experimental days. 15N, a stable N isotope, was measured in biological samples by mass spectrometry.

RESULTS

Compared with control rats, Group 1 animals showed significant reductions in N intake and food efficiency (p < 0.05, both). In addition, the weight of the gastrocnemius muscle, its total N content and the dietary N content of this muscle were significantly lower in Group 1 than in control animals (p < 0.05, all). In rats from Group 2, mean values of N intake, food efficiency, gastrocnemius N content and the amount of dietary N incorporated into this muscle were similar to those in control rats, and (with the exception of gastrocnemius N total content) significantly higher than those in non-treated cirrhotic rats (p < 0.05, all).

CONCLUSIONS

A variety of nutritional disturbances were detected in rats from the early stages of liver cirrhosis. Low doses of IGF-I were found to reverse most of these changes. These results stimulate further studies to determine whether IGF-I might be useful in the correction of the malnutrition present in patients with liver cirrhosis.

Modulation of glucose production by indomethacin and pentoxifylline in healthy humans

Indomethacin, an inhibitor of prostaglandin synthesis that modulates cytokine production, increases hepatic glucose output (HGO) in humans. However, prostaglandins stimulate glucose production in vitro. To investigate the mechanism of HGO stimulation by indomethacin, we compared the effect of pentoxifylline, an inhibitor of cytokine production, versus saline (study 1, n = 6) and of indomethacin versus the combination of indomethacin and pentoxifylline (study 2, n = 5) on basal HGO. HGO was measured by primed, continuous infusion of 3-3H-glucose. In study 1, pentoxifylline infusion resulted in an immediate, transient decrease of HGO of approximately 50% (from 12.9 +/- 0.4 to 6.0 +/- 1.7 micromol/kg/min after 15 minutes, P < .03 v control). There were no differences in concentrations of glucoregulatory hormones between the two experiments. In study 2, after indomethacin administration, HGO increased transiently by approximately 84% (from 9.7 +/- 0.7 at baseline to 16.7 +/- 2.4 micromol/kg/min after 135 minutes, P < .05). However, pentoxifylline did not affect the increase in HGO induced by indomethacin. There were no differences in concentrations of glucoregulatory hormones between the two experiments. Therefore, indomethacin stimulates HGO by mechanisms unrelated to glucoregulatory hormones, prostaglandins, or cytokines.

Metabolic, endocrine, haemodynamic and pulmonary responses to different types of exercise in individuals with normal or reduced liver function

The liver is central to the metabolic response to exercise but measurements of effects of reduced liver function on the physiological adaptation to exercise are scarce. We investigated metabolic, endocrine, pulmonary and haemodynamic responses to exercise in 15 healthy untrained controls (Co) and in 30 subjects with reduced liver function (i.e. liver cirrhosis, Ci). The following protocols were used: protocol 1 maximal oxygen uptake (VO2max) and anaerobic threshold (AT), protocol 2 stepwise increases in exercise intensity from 0 to 40% VO2max giving steady-stage conditions, protocol 3 1 h exercise at 20% VO2max. Muscle glycogen content was determined in 15 Ci. Spirometry was essentially normal in Ci.

RESULT

protocol 1 Ci had impaired VO2max and reduced AT (P < 0.05). Basal plasma concentrations of insulin, glucagon, growth hormone and adrenaline were increased in Ci (P < 0.05); cortisol was normal. During exercise, only glucagon remained different between groups. In protocol 2 Ci had decreased resting respiratory exchange ratio (RQ: p < 0.05) associated with increased plasma concentrations of free fatty acids and glycerol. They had disproportionately enhanced lipolysis and RQ. heart rate (+24%), ventilation (+28%), thermal effects of exercise (+31%) and intrapulmonary shunt volume (+76%), which accounted for 11.7 (SD 3.0) or 7.4 (SD 0.9%) of cardiac output during exercise in Ci and Co, respectively (P < 0.05 for all the differences reported). The metabolic effects of Ci were independent of the clinical and nutritional state of the patients. In protocol 3 muscle glycogen content was highly variable in Ci, but mean values were normal [16.9 (SD 8.9) mumol.g-1 wet mass]. Glycogen content positively correlated with resting and exercise-induced RQ, but negatively correlated with the exercise-induced alterations in plasma glucose concentration. From these results we concluded that with reduced liver function VO2max and AT are reduced, but metabolic, pulmonary and haemodynamic responses per unit power output are enhanced. Muscle glycogen content would seem to contribute to the metabolic response, but its mobilization to be limited in individuals with reduced liver function.

Energy metabolism in portal hypertension in children

This study was designed to assess resting energy expenditure (REE) and nutritional status in children with hepatic and prehepatic portal hypertension in comparison with healthy controls. Twenty-five patients with portal hypertension (PHT) and a history of variceal bleeding were compared with 14 healthy volunteers selected after matching for age and sex. PHT patients were allocated to one of two groups: 11 children with liver cirrhosis and/or chronic hepatitis, aged 14.0 +/- 3.3 y (means +/- SD) or 14 children with extrahepatic portal vein obstruction, aged 12.3 +/- 2.8 y. The control group consisted of 14 healthy children, aged 14.0 +/- 1.8 y. REE (indirect calorimetry) assessed after an overnight fast was significantly higher in PHT patients than in controls when related to body mass (143.7 +/- 29.5 and 116.1 +/- 5.9 kJ/kg, respectively; p < 0.004), lean body mass (168.0 +/- 28.9 and 146.4 +/- 14.1 kJ/kg, respectively; p < 0.02), and body surface area (7480 +/- 736 and 6590 +/- 567 kJ/1.73 m2, respectively; p < 0.001). The ratios of measured REE to basal energy expenditure calculated from standard equations (Schofield equations) indicated higher REE in PHT patients (102.24 +/- 6.90% and 93.54 +/- 4.47%, respectively; p < 0.001). Fat was the predominant source of energy in both PHT patients and controls; the percentage of nonprotein energy derived from carbohydrate oxidation was equaled: 36.04 +/- 18.84% and 37.15 +/- 15.71%, respectively. Analysis of percentage of undernutrition in PHT patients and controls revealed significant differences (44% and 21%, respectively; p < 0.001). Children with PHT are susceptible to malnutrition and have elevated REE compared with healthy controls. Fat is the principal basal state oxidative substrate for patients with PHT and healthy children.

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.

Glycerol metabolism in patients with alcohol-induced liver cirrhosis

The clearance rate of glycerol has been found to be impaired in alcoholic liver disease. However it remains unclear, if this can be ascribed to a defect of hepatic gluconeogenesis. Thus, the purpose of this work was to investigate glycerol clearance and hepatic glucose production in patients with liver cirrhosis. 13 patients with alcohol-induced Child B cirrhosis and 8 healthy volunteers were studied. Rates of appearance (R(a)) of glycerol, glucose and alanine were determined using stable isotope techniques. In addition indocyanine green clearance (ICGC) and plasma substrate concentrations were measured. Clearance rates were calculated as R(a) divided by the corresponding substrate concentration. R(a) of glycerol in patients was not different from controls, but glycerol clearance was significantly reduced (29 +/- 3 vs. 41 +/- 4 ml/kg/min). No differences in R(a) of glucose and alanine and corresponding plasma concentrations were observed. ICGC in patients was about 35% lower than reference values. Diminished glycerol clearance in patients with liver cirrhosis was not due to impaired hepatic gluconeogenesis. Since glycerol is almost completely extracted by the liver decreased glycerol clearance possibly simply reflected compromised liver perfusion as seen by reduced ICGC.

Sex differences in the adaptation of glucose metabolism to short-term fasting: effects of oral contraceptives

The adaptation to long-term starvation is different in men and women. To evaluate whether there are also sex differences during short-term fasting (< 24 hours), we studied glucose metabolism after 16 and again after 22 hours of starvation in healthy subjects: six men, six women in both the follicular and luteal phases of their menstrual cycle, and six women on oral contraceptives ([OCC] day 12 of cycle). Glucose oxidation was measured by indirect calorimetry, and hepatic glucose output by infusion of 3-3H-glucose. There were no differences in hepatic glucose output between men and women during short-term fasting. The basal (16 hours) plasma glucose concentration was lower in women on OCC than in men (P < .05). Prolongation of the postabsorptive state induced a similar decline in plasma glucose concentrations in all groups. Basal (16 hours) glucose oxidation was lower in women on OCC than in men (P < .05). Prolongation of the postabsorptive state by 6 hours caused a significant decrease in glucose oxidation only in men. After 22 hours of fasting, glucose oxidation was lower in women on OCC than in women with normal menstrual cycles. In conclusion, the metabolic adaptation to the postabsorptive state (< 24 hours of fasting) is regulated differently in women on OCC as compared with women with normal menstrual cycles and men. These differences preclude inclusion of women on OCC in studies of glucose metabolism in the postabsorptive state.

Lipid metabolism and substrate oxidation during intravenous fructose administration in cirrhosis

We used isotope dilution techniques (constant intravenous [IV] infusion of 2-3H-glycerol and 1-14C-palmitate) and indirect calorimetry to measure lipid kinetics and substrate oxidation rates during IV fructose administration at 200 and then 500 mg/kg/h in eight cirrhotic patients and seven normal control subjects. Fasting plasma glucose, glycerol, and glycerol appearance rate (Ra) were similar in both groups, but insulin levels were fourfold higher in cirrhotics (P < .01). Fasting serum nonesterified fatty acid (NEFA) levels (cirrhotics, 869 +/- 124, controls, 717 +/- 90 mumol/L) and NEFA Ra (7.1 +/- 0.8 v 5.5 +/- 0.9 mumol/min/kg) were higher in cirrhotics, but the differences were not significant. Plasma fructose was similar in both groups at both fructose infusion rates. Fructose appeared to stimulate insulin secretion. With i.v. fructose, serum NEFA levels decreased, reaching similar low levels when 500 mg/kg/h was infused, due to a reduction in NEFA Ra and an increase in the NEFA metabolic clearance rate (MCR). Glycerol levels showed little change. As glycerol Ra decreased by less than 20% in both groups, the decrease in serum NEFA was primarily due to enhanced reesterification of fatty acids both within adipose tissue (preventing their release) and in other tissues (enhancing their removal from plasma). Although total fructose utilization was normal in cirrhotics, they oxidized more of the infused fructose; nonoxidative disposal was reduced (first step, 242 +/- 12 v 318 +/- 16 mg/kg in 2 hours, P < .002; second step, 657 +/- 32 v 786 +/- 21 mg/kg in 2 hours, P < .005). Although tissue fructose uptake is insulin-independent, insulin resistance in cirrhosis may influence the intracellular metabolism of fructose.

Body composition in nonalcoholic cirrhosis: the effect of disease etiology and severity on nutritional compartments

BACKGROUND/AIMS

Previous studies of body composition in cirrhosis have either measured only one body compartment, used alcoholic subjects, or not corrected body composition for physical characteristics. The aim of this study was to perform a detailed analysis of body composition in subjects with nonalcoholic cirrhosis.

METHODS

Simultaneous measurements of total body potassium and total body water were performed and values of body cell mass and body fat were corrected for physical characteristics.

RESULTS

Child's class C patients had a significantly lower mean total body potassium index (i.e., percent observed value/expected value) and body fat index than class A or B patients. Eighty-one percent of class C patients had simultaneous reductions in body fat and body cell mass, and 71% of patients with class A disease had a significant reduction in either or both compartments. Nine patients showed the pattern of tissue loss seen with short-term starvation. Fourteen patients showed the pattern of tissue loss seen in physiological stress.

CONCLUSIONS

Severe liver disease is characterized by significant reductions in body fat and body cell mass, most class A patients have a significant reduction in some nutritional compartments, and the pattern of tissue loss may reflect mechanisms of tissue wasting.

Progressive alterations in lipid and glucose metabolism during short-term fasting in young adult men

Stable isotope tracers and indirect calorimetry were used to evaluate the progressive alterations in lipid and glucose metabolism after 12, 18, 24, 30, 42, 54, and 72 h of fasting in six healthy male volunteers. The rates of appearance (Ra) of glycerol and palmitic acid in plasma doubled from 2.08 +/- 0.22 and 1.63 +/- 0.20 mumol.kg-1 x min-1, respectively, after 12 h to 4.36 +/- 0.36 and 3.26 +/- 0.40 mumol.kg-1 x min-1, respectively, after 72 h of fasting (P < 0.01). Of the total increase in lipid kinetics, 60% occurred between 12 and 24 h of fasting; the greatest interval change occurred between 18 and 24 h of fasting. Glucose Ra and plasma concentration decreased by approximately 25% between 12 h (11.0 +/- 0.4 mumol.kg-1 x min-1 and 5.58 +/- 0.08 mmol/l, respectively) and 72 h (8.3 +/- 0.3 mumol.kg-1 x min-1 and 4.14 +/- 0.10 mmol/l, respectively) of fasting (P < 0.01), but no statistically significant changes occurred between 18 and 24 h of fasting. Plasma insulin decreased by approximately 50% between 12 h (64.6 +/- 12.9 pmol/l) and 72 h (30.1 +/- 7.9 pmol/l) of fasting (P < 0.001). Of the total decline in plasma insulin, 70% occurred within the first 24 h of fasting. These results demonstrate that the mobilization of adipose tissue triglycerides increases markedly between 18 and 24 h of fasting in young adult men. The early alterations in lipid metabolism are associated with a decline in circulating insulin but do not seem to be regulated by changes in glucose kinetics or plasma glucose concentrations.

Failure of ursodeoxycholic acid to dissolve radiolucent gallstones in patients with cystic fibrosis

Ursodeoxycholic acid has been used widely to dissolve cholesterol gallstones and more recently was shown to improve clinical symptoms and biochemical indices in different chronic liver diseases, including that associated with cystic fibrosis. We treated 10 cystic fibrosis patients (5 males, 5 females, age range 2-22 years) with pancreatic insufficiency and normal liver function with ursodeoxycholic acid 15-20 mg/kg/day. Seven patients had radiolucent gallstones (in 3 cases associated with biliary sludge) and 3 had sludge; all were asymptomatic. Before treatment, the gallbladder was well opacified in oral cholecystogram. The gallbladder was scanned by ultrasound in similar conditions and by the same operator before administration of ursodeoxycholic acid and after a median period of treatment of 16 months (range 11-32 months). During treatment, all patients remained asymptomatic and the relative proportion of ursodeoxycholic acid in duodenal bile increased from 4.7 +/- 3.2% at baseline to 34.7 +/- 8.6%. Complete or partial dissolution of gallstones was never observed and the maximum diameter of stones increased from a mean of 6.1 +/- 3.4 to 8.0 +/- 5.3 mm; in one case the development of biliary sludge occurred during bile acid therapy. Sludge disappeared in 1 of the 6 patients who initially had it, while in 2 cases its volume increased. We conclude that ursodeoxycholic acid is not effective in most CF patients with gallstones, probably because cholesterol is not the main component of stone or sludge.

Therapy with ursodeoxycholic acid in cholestatic liver disease

Ursodeoxycholic acid (UDCA) has beneficial effects on symptoms, liver biochemistry and, possibly, liver histology in primary biliary cirrhosis and other cholestatic liver diseases. UDCA may exert these beneficial effects by a direct hepatoprotective effect, by influencing the enterohepatic circulation of endogenous bile salts, by enhancing bile flow through a cholehepatic shunt mechanism or by immune modulation. In the present article, established and potential indications for UDCA are reviewed.

Metabolic responses to lipid infusions in patients with liver cirrhosis

Energy expenditure, whole body substrate oxidation rates and arterial substrate concentrations were measured in 14 patients with liver cirrhosis and 13 control subjects before and during sequential infusions of a long chain (LCT) or a medium chain triglyceride emulsion (MCT) without and with concomitant insulin plus glucose infusions. Resting energy expenditure, basal substrate oxidation rates and the arterial concentrations of glucose, lactate, triglycerides and ketones were normal, whereas plasma free fatty acids and glycerol were both increased in patients with liver cirrhosis. The arterial plasma triglyceride and free fatty acid concentrations as well as whole body lipid oxidation rate rose in response to LCT in both groups and the maximum lipid oxidation rate was 1.1 or 1.3 mg/kg fat free mass x min in controls and in cirrhotics, respectively (n.s.). Concomitantly, glucose oxidation rate fell to 65% of basal values in controls (p < 0.01), but remained nearly unchanged in the cirrhotic group (89% of the basal value; n.s.). The increase in plasma ketones was reduced to 67% of control values in liver cirrhosis (p < 0.01). Only a slight effect on energy expenditure was observed in both groups. When compared to controls, liver cirrhosis impaired insulin-induced increases in glucose disposal (-30%, p < 0.01) and in non oxidative glucose metabolism (-93%, p < 0.01). Concomitantly, normal increases in energy expenditure, glucose oxidation rate and the arterial plasma lactate concentrations and normal decreases in lipolysis, lipid oxidation and ketogenesis were observed in patients with liver cirrhosis. When lipids were given together with glucose, energy expenditure and lipid oxidation increased in controls, but glucose was the preferred fuel oxidised and lipid-induced thermogenesis was reduced in the cirrhotic group. Using a 50% MCT-emulsion, plasma free fatty acid concentrations further increased, but energy expenditure and lipid oxidation remained unchanged in both groups and further increases in plasma ketones were only observed in controls. Infusing glycerol in a subgroup of patients showed no thermogenic effect and a reduced glycerol clearance in liver cirrhosis.

Energy expenditure and substrate oxidation in patients with cirrhosis: the impact of cause, clinical staging and nutritional state

Many clinicians subjectively feel that cirrhotic patients frequently have clinical signs of hypermetabolism. However, it is unknown whether hypermetabolism is a constant feature of chronic liver disease, corresponds to liver destruction and repair or is of prognostic value. This article is about resting energy expenditure and substrate oxidation rates in 123 patients with biopsy-proven cirrhosis differing with respect to cause, duration of the disease, biochemical parameters of parenchymal cell damage, cholestasis, liver function, number of complications, clinical staging and nutritional state. Resting energy expenditure varied between 1,090 and 2,300 kcal/day and differed from the predicted values in 70% of the patients. Resting energy expenditure was closely related to fat-free mass, and 52% of the variability could be explained by fat-free mass, age and sex. Of all the patients, 18% were hypermetabolic and 31% were hypometabolic. Hypermetabolism showed no strict association with the cause of cirrhosis, the duration of the disease, liver function, cholestasis, cell damage, clinical staging, blood hemoglobin, plasma thyroid hormone levels or human leukocyte antigens. An increased resting energy expenditure was associated with significant losses of muscle, body cell mass and extracellular mass at unchanged body fat, whereas fat and fat-free mass were increased in hypometabolic patients when compared with normometabolic patients. Lipid oxidation was increased, but glucose oxidation was reduced in nearly all patients with cirrhosis. This was most pronounced at advanced stages of liver disease. Although similar with respect to liver function and clinical staging, 76.2% of hypermetabolic patients had transplants within the observation period, compared with only 16.7% and 8.1% in the normometabolic group and hypometabolic group, respectively. Posttransplantation mortality was independent of pretransplantation resting energy expenditure, but it increased significantly in patients with losses in body cell mass. In conclusion, hypermetabolism is not a constant feature of cirrhosis and results more from extrahepatic than from hepatic factors. It may cause malnutrition and contributes to the clinical outcome of patients with chronic liver disease.