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Screening of Amino Acids as a Safe Energy Source for Isolated Rat Pancreatic Acini
Abstract
Objectives
Amino acids play an essential role in protein synthesis, metabolism and survival of pancreatic acini. Adequate nutritional support is important for acute pancreatitis treatment. However, high concentrations of arginine and lysine may induce acute pancreatitis. The study aimed to identify the most suitable L-amino acids as safe energy sources for pancreatic acinar cells.
Methods
Pancreatic acini were isolated from male Wistar rats. Effects of amino acids (0.1-20 mM) on uncoupled respiration of isolated acini were studied with a Clark electrode. Cell death was evaluated with fluorescent microscopy and DNA gel electrophoresis.
Results
Among the tested amino acids, glutamate, glutamine, alanine, lysine and aspartate were able to stimulate the uncoupled respiration rate of isolated pancreatic acini, while arginine, histidine and asparagine were not. Lysine, arginine and glutamine (20 mM) caused complete loss of plasma membrane integrity of acinar cells after 24 h of incubation. Glutamine also caused early (2–4 h) cell swelling and blebbing. Aspartate, asparagine and glutamate only moderately decreased the number of viable cells, while alanine and histidine were not toxic. DNA fragmentation assay and microscopic analysis of nuclei showed no evidence of apoptosis in cells treated with amino acids.
Conclusions
Alanine and glutamate are safe and effective energy sources for mitochondria of pancreatic acinar cells.
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Plasma amino acid levels are altered upon many pathological conditions including acute pancreatitis. It is unclear whether amino acids can be used as specific biomarker of acute pancreatitis severity or recovery. Development of acute pancreatitis is associated with mitochondrial dysfunction and decreased cytosolic ATP level. Sodium pyruvate is considered as a potential treatment of pancreatitis due to its ability to sustain mitochondrial oxidative and ATP-productive capacity in vitro. This study investigated the effect of sodium pyruvate on pancreatic morphology and plasma amino acid levels in rats with acute pancreatitis. Acute pancreatitis in rats was induced by administration of l-arginine (5 g/kg) Experimental treatment group received sodium pyruvate (1 g/kg) for 4 days. On day 8 of the experiment, animals were killed, blood was collected and plasma amino acid concentration was determined with high-performance liquid chromatography. Histological examination showed large areas of fibrosis in the pancreas of animals treated with l-arginine irrespectively of sodium pyruvate administration. Sodium pyruvate improved the plasma amino acid levels. Rats with acute pancreatitis had significantly lower levels of most essential and non-essential amino acids and increased glutamate and aspartate in plasma. Administration of sodium pyruvate completely or partially restored the levels of methionine, phenylalanine, tryptophan, leucine, isoleucine, aspartate, asparagine and ornithine levels, while increasing glutamine and serine to levels significantly higher than control. Plasma lysine, alanine, arginine and taurine remained unaffected in all experimental groups. Sodium pyruvate may be considered for use as a maintenance therapy in acute pancreatitis.
Due to the severe toxicity posed by chemotherapeutic drugs, adjuvant nutritional intervention has gained increased attention in the treatment of pancreatic cancer (PC). Amino acid (AA) metabolism is aberrantly regulated in PC and circulating histidine (His) levels are low in PC patients. We hypothesized that His uptake and/or metabolism is dysregulated in PC and that combining His with gemcitabine (Gem), a drug used in the treatment of PC, will enhance the anti-cancer effects of Gem. We performed in vitro and in vivo studies to determine the anticancer effect of the combination of His and Gem against lethal PC. We demonstrate that circulating His levels are low in both human subjects and genetically engineered mice exhibiting pancreatic tumors. Interestingly, the expression of histidine ammonia lyase, an enzyme involved in His catabolism, is higher in PC compared to normal subjects. His + Gem exerts a more potent cytotoxic effect in PC cells compared to individual treatments. His treatment results in a profound increase in His accumulation, accompanied by a depletion of a number of AAs, promoting cancer cell survival and/or glutathione (GSH) synthesis. His but not Gem increases hydrogen peroxide and depletes cellular GSH. Supplementation with GSH protects cells against His + Gem-induced cytotoxicity. Further, our in vivo studies demonstrate that His + Gem potently reduced tumor mass and improved mouse survival. Taken together, our data suggest that PC cells exhibit an aberrant His uptake/accumulation which, in turn, leads to oxidative stress and depletion of AA pool, thereby enhancing the anticancer effect of Gem.
Nitric oxide is generated from nitric oxide synthase following hyperglycemia-induced oxidative stress during the course of diabetes mellitus (DM). We examined the temporal immuno-expression of neuronal nitric oxide synthase (nNOS) in the pancreas of diabetic and non-diabetic rats using immunohistochemical, immunofluorescence and western blot techniques 12 h, 24 h, 1 week, 2 weeks, 1, 8 and 15 months after induction of DM. nNOS co-localized with pancreatic beta cells but disappears 12 h after the onset of DM. In contrast, the nNOS content of pancreatic nerves increased significantly (p < 0.001) 24 h after the induction of DM, and decreased sharply thereafter. However, nNOS-positive ganglion cells were observed even 15 months post-diabetes. ROS increased by more than 100% two months after the onset of DM compared to non-diabetic control but was significantly (p < 0.000001) reduced at 9 months after the induction of DM. The pancreatic content of GSH increased significantly (p < 0.02) after 9 months of DM. Although, TBARS content was significantly (p < 0.009; p < 0.002) lower in aged (9 months) non-diabetic and DM rats, TBARS rate was markedly (p < 0.02) higher 9 months after the induction of DM when compared to younger age group. In conclusion, nNOS is present in pancreatic beta cell, but disappears 12 h after the onset of diabetes. In contrast, the tissue level of nNOS of pancreatic nerves increased in the first week of diabetes, followed by a sharp reduction. nNOS may play important roles in the metabolism of pancreatic beta cell.
Acute pancreatitis (AP) is an acute inflammatory process of the pancreas that is characterized by severe abdominal pain, elevated pancreatic enzymes, and pancreatic changes on abdominal imaging. AP is, by nature, an inflammatory process that leads to protein catabolism and an increased metabolic rate, highlighting the strong need for early nutritional support in the initial management of the disease process. The goal of nutritional support in acute pancreatitis is to correct the negative nitrogen balance to reduce inflammation and improve outcomes. Many trials and multiple systemic reviews and meta-analyses have examined the best modality, timing, and composition of nutritional support for acute pancreatitis. Early enteral nutrition has emerged as an important aspect of the clinical management of AP. This narrative review aimed to provide an overview of the clinical management of nutrition in acute pancreatitis based on the currently available data.
The ability of the mitochondria to compensate for energy expenditure of cells largely depends on the availability of the oxidative substrates, transported across the intact plasma membrane with molecular carriers of limited affinity. The aim of this study was to investigate the dependence of adaptive respiratory responses of mitochondria of intact hepatocytes on the oxidative substrates. Basal and FCCP-stimulated respiration rates were determined with Clark electrode. After 15-minute incubation in the medium with the oxidative substrates or their combinations (glutamine, pyruvate, succinate, monomethyl succinate, α-ketoglutarate, dimethyl-α-ketoglutarate (2 mM) or glucose (10 mM)), isolated hepatocytes were added into the respiratory chamber. FCCP concentration was 0.25, 0.5 and 1 μM. The adaptive capacity of mitochondria was characterized by the maximal uncoupled respiration rate (the highest respiration rate among all tested FCCP concentrations), the optimal FCCP concentration (the concentration at which the maximal rate is achieved) and the area under the curve (AUC) of the dependence of the uncoupled respiration rate on FCCP concentration. The adaptive capacity of mitochondria, evaluated by AUC, increases in this order of substrates: glucose (0.063 r.u.), endogenous substrates (0.067 r.u.), glutamine (0.092 r.u.), pyruvate (0.113 r.u.), α-ketoglutarate (0.113 r.u.), succinate (0.152 r.u.), dimethyl-α -ketoglutarate (0.156 r.u.), and monomethyl succinate (0.172 r.u.). The adaptive capacity of mitochondria of hepatocytes seems to be partly dependent on plasma membrane transporters affinities (Km) to the oxidative substrates. The presence of glucose in the medium does not improve the adaptive capacity of hepatic mitochondria.
The dependence of uncoupled respiratory capacity of intact pancreatic acini on oxidative substrate supply and functional cell state has not yet been studied in detail. In this study, the respiratory responses of isolated pancreatic acini to FCCP were measured with Clark electrode and mitochondrial membrane potential was assessed with rhodamine123 fluorescence. The response of acini to FCCP was characterized with maximal uncoupled respiration rate, optimal FCCP concentration, respiration acceleration and deceleration. Maximal uncoupled respiration rate substantially increased upon the oxidation of glucose + glutamine (3.03 ± 0.54 r.u.), glucose + glutamine + pyruvate (2.82 ± 0.51 r.u.), glucose + isocitrate (2.71 ± 0.33 r.u.), glucose + malate (2.75 ± 0.38 r.u.), glucose + monomethyl-succinate (2.64 ± 0.42 r.u.) or glucose + dimethyl-α-ketoglutarate (2.36 ± 0.33 r.u.) comparing to glucose alone (1.73–2.02 r.u.) or no substrate (1.76 ± 0.33 r.u.). The optimal FCCP concentration was the highest (1.75 μM) upon glucose + glutamine + pyruvate combination and the lowest (0.5 μM) upon glutamate, combinations of glucose with isocitrate, malate, succinate or α-ketoglutarate. Respiration acceleration after FCCP application was the highest with dimethyl-α-ketoglutarate. Following the peak respiration, time-dependent deceleration was observed. It increased with FCCP concentration and depended on oxidative substrate type. Deceleration was the highest upon malate or isocitrate oxidation but was not observed in case of glutamine or dimethyl-α-ketoglutarate oxidation. Pyruvate alone or in combination with glutamine and glucose significantly decreased the depolarizing effect of FCCP on mitochondrial membrane potential and increased respiration elasticity coefficient with respect to the membrane potential change. Thus, in pancreatic acinar cells, the combination of pyruvate, glutamine and glucose enables the optimal adaptive respiratory response to membrane depolarization.
Background
Living tissues maintain a fine balance between protein synthesis and protein breakdown rates. Animal studies indicate that protein synthesis rates are higher in organs when compared with skeletal muscle tissue. As such, organ and tumour protein synthesis could have major effects on whole‐body protein metabolism in wasting disorders such as cancer cachexia. We aimed to assess protein synthesis rates in pancreatic tumour tissue and healthy pancreas, liver, and skeletal muscle tissue in vivo in humans.
Methods
In eight patients with pancreatic cancer undergoing pancreaticoduodenectomy, primed continuous infusions with L‐[ring‐¹³C6]phenylalanine and L‐[3,5‐²H2]tyrosine were started prior to surgery and continued throughout the surgical procedures. During surgery, plasma samples and biopsies from the pancreas, pancreatic tumour, liver, and vastus lateralis muscle were taken. Post‐absorptive fractional protein synthesis rates were determined by measuring incorporation of labelled L‐[ring‐¹³C6]phenylalanine in tissue protein using the weighed plasma L‐[ring‐¹³C6]phenylalanine enrichments as the precursor pool.
Results
Five male patients and three female patients with a mean age of 67 ± 2 years were included into this study. Plasma L‐[ring‐¹³C6]phenylalanine enrichments (6–9 mole per cent excess) did not change during surgery (P = 0.60). Pancreatic tumour protein synthesis rates were 2.6‐fold lower than surrounding pancreatic tissue protein synthesis rates (0.268 ± 0.053 vs. 0.694 ± 0.228%/h, respectively; P = 0.028) and 1.7‐fold lower than liver protein synthesis rates (0.268 ± 0.053 vs. 0.448 ± 0.043%/h, respectively; P = 0.046). Among healthy organ samples, protein synthesis rates were 20‐fold and 13‐fold higher in pancreas and liver, respectively, compared with skeletal muscle tissue (0.694 ± 0.228 and 0.448 ± 0.043 vs. 0.035 ± 0.005%/h, respectively; P < 0.05).
Conclusions
Liver and pancreas tissue protein synthesis rates are higher when compared with pancreatic tumour and skeletal muscle tissue protein synthesis rates and can, therefore, strongly impact whole‐body protein metabolism in vivo in humans.
Pancreatic acinar cells require high rates of amino acid uptake for digestive enzyme synthesis, but excessive concentrations can trigger acute pancreatitis (AP) by mechanisms that are not well understood. We have used three basic natural amino acids L-arginine, L-ornithine, and L-histidine to determine mechanisms of amino acid-induced pancreatic injury and whether these are common to all three amino acids. Caffeine markedly inhibited necrotic cell death pathway activation in isolated pancreatic acinar cells induced by L-arginine, but not L-ornithine, whereas caffeine accelerated L-histidine-induced cell death. Both necroptosis inhibitors of RIPK1 and RIPK3 and a necroptosis activator/apoptosis inhibitor z-VAD increased cell death caused by L-histidine, but not L-arginine or L-ornithine. Cyclophilin D knock-out (Ppif-/-) significantly attenuated cell death induced by L-histidine, but not L-arginine, or L-ornithine. Allosteric modulators of calcium-sensing receptor (CaSR) and G-protein coupled receptor class C group 6 member A (GPRC6A) had inhibitory effects on cell death induced by L-arginine but not L-ornithine or L-histidine. We developed a novel amino acid-induced AP murine model with high doses of L-histidine and confirmed AP severity was significantly reduced in Ppif-/- vs. wild type mice. In L-arginine-induced AP neither Ppif-/-, caffeine, or allosteric modulators of CaSR or GPRC6A reduced pancreatic damage, even though CaSR inhibition with NPS-2143 significantly reduced pancreatic and systemic injury in caerulein-induced AP. These findings demonstrate marked differences in the mechanisms of pancreatic injury induced by different basic amino acids and suggest the lack of effect of treatments on L-arginine-induced AP may be due to conversion to L-ornithine in the urea cycle.
We conducted a comprehensive analysis to evaluate the treatment efficacy and safety of enteral nutrition (EN) and parenteral nutrition (PN) in severe acute pancreatitis (SAP) patients, and to provide a basis for their evidence based application in a clinical setting. We conducted a systematic online search of the PubMed, Web of Science, Wanfang, and China National Knowledge Infrastructure databases, from their inception to November 2017. Studies were subjected to further screening if they met the inclusion/exclusion criteria. Eleven studies were subjected to qualitative and quantitative synthesis; these included a total of 562 patients (281 for EN and 281 for PN). No significant heterogeneity across studies was found. The results indicated that EN can significantly decrease the mortality rate (relative risk [RR] = 0.43, 95% confidence interval [CI]: 0.23–0.78, P=0.006), and lowers the risk of infection and complications (RR = 0.53, 95% CI: 0.39–0.71, P=0.000) more so than does PN. The EN group had a similar risk of multiple organ failure (MOF) compared with the PN group (RR = 0.63, 95% CI: 0.39–1.02, P=0.059). The use of EN was also found to significantly reduce mean hospitalization time (mean difference = −2.93, 95% CI: −4.52–1.34, P=0.000). No publication bias was found. Our meta-analysis suggested that EN, but not PN, significantly reduced the risk of mortality, infection, and complications for patients with SAP. EN support also decreased the rate of MOF and surgical intervention. EN is recommended as an initial treatment option for patients with SAP.
Acute pancreatitis (AP), a human disease in which the pancreas digests itself, has substantial mortality with no specific therapy. The major causes of AP are alcohol abuse and gallstone complications, but it also occurs as an important side effect of the standard Asparaginase-based therapy for childhood acute lymphoblastic leukaemia. Previous investigations into the mechanisms underlying pancreatic acinar cell death induced by alcohol metabolites, bile acids or Asparaginase indicated that loss of intracellular ATP generation is a significant factor. In isolated mouse pancreatic acinar cells or cell clusters, we now report that removal of extracellular glucose had little effect on this ATP loss, suggesting that glucose metabolism was severely inhibited under these conditions. Surprisingly, we show that replacing glucose with galactose prevented or markedly reduced the loss of ATP and any subsequent necrosis. Addition of pyruvate had a similar protective effect. We also studied the effect of galactose in vivo in mouse models of AP induced either by a combination of fatty acids and ethanol or Asparaginase. In both cases, galactose markedly reduced acinar necrosis and inflammation. Based on these data we suggest that galactose feeding may be used to protect against AP.
Introduction
Acute pancreatitis (AP) is an inflammatory disease with no specific treatment. Mitochondrial injury followed by ATP depletion in both acinar and ductal cells is a recently discovered early event in its pathogenesis. Importantly, preclinical research has shown that intracellular ATP delivery restores the physiological function of the cells and protects from cell injury, suggesting that restoration of energy levels in the pancreas is therapeutically beneficial. Despite several high quality experimental observations in this area, no randomised trials have been conducted to date to address the requirements for energy intake in the early phase of AP.
Methods/design
This is a randomised controlled two-arm double-blind multicentre trial. Patients with AP will be randomly assigned to groups A (30 kcal/kg/day energy administration starting within 24 hours of hospital admission) or B (low energy administration during the first 72 hours of hospital admission). Energy will be delivered by nasoenteric tube feeding with additional intravenous glucose supplementation or total parenteral nutrition if necessary. A combination of multiorgan failure for more than 48 hours and mortality is defined as the primary endpoint, whereas several secondary endpoints such as length of hospitalisation or pain will be determined to elucidate more detailed differences between the groups. The general feasibility, safety and quality checks required for high quality evidence will be adhered to.
Ethics and dissemination
The study has been approved by the relevant organisation, the Scientific and Research Ethics Committee of the Hungarian Medical Research Council (55961-2/2016/EKU). This study will provide evidence as to whether early high energy nutritional support is beneficial in the clinical management of AP. The results of this trial will be published in an open access way and disseminated among medical doctors.
Trial registration
The trial has been registered at the ISRCTN (ISRTCN 63827758).
Background
Lysinuric protein intolerance (LPI) is a rare metabolic disease resulting from recessive-inherited mutations in the SLC7A7 gene encoding the cationic amino-acids transporter subunit y⁺LAT1. The disease is characterised by protein-rich food intolerance with secondary urea cycle disorder, but symptoms are heterogeneous ranging from infiltrative lung disease, kidney failure to auto-immune complications. This retrospective study of all cases treated at Necker Hospital (Paris, France) since 1977 describes LPI in both children and adults in order to improve therapeutic management.
Results
Sixteen patients diagnosed with LPI (12 males, 4 females, from 9 families) were followed for a mean of 11.4 years (min-max: 0.4-37.0 years). Presenting signs were failure to thrive (n = 9), gastrointestinal disorders (n = 2), cytopenia (n = 6), hyperammonemia (n = 10) with acute encephalopathy (n = 4) or developmental disability (n = 3), and proteinuria (n = 1). During follow-up, 5 patients presented with acute hyperammonemia, and 8 presented with developmental disability. Kidney disease was observed in all patients: tubulopathy (11/11), proteinuria (4/16) and kidney failure (7/16), which was more common in older patients (mean age of onset 17.7 years, standard deviation 5.33 years), with heterogeneous patterns including a lupus nephritis. We noticed a case of myocardial infarction in a 34-year-old adult. Failure to thrive and signs of haemophagocytic-lymphohistiocytosis were almost constant. Recurrent acute pancreatitis occurred in 2 patients. Ten patients developed an early lung disease. Six died at the mean age of 4 years from pulmonary alveolar proteinosis. This pulmonary involvement was significantly associated with death. Age-adjusted plasma lysine concentrations at diagnosis showed a trend toward increased values in patients with a severe disease course and premature death (Wilcoxon p = 0.08; logrank, p = 0.17). Age at diagnosis was a borderline predictor of overall survival (logrank, p = 0.16).
Conclusions
As expected, early pulmonary involvement with alveolar proteinosis is frequent and severe, being associated with an increased risk of death. Kidney disease frequently occurs in older patients. Cardiovascular and pancreatic involvement has expanded the scope of complications. A borderline association between increased levels of plasma lysine and poorer outome is suggested. Greater efforts at prevention are warranted to optimise the long-term management in these patients.
Acute pancreatitis is an inflammatory disease caused by several factors such as viral infection, drugs, and diagnostic endoscopy. The aim of this study was to evaluate the potential protective or therapeutic effects of L-lysine on pancreatitis induced by L-arginine in mice.
Four groups of mice (10 in each group) were assessed. Group I was the control. Animals in groups II-IV were injected intraperitoneally with L-arginine hydrochloride (400 mg/kg body weight [bw]) for 3 days. Group III animals were orally pre-treated with L-lysine (10 mg/kg bw), whereas group IV animals were orally post-treated with L-lysine (10 mg/kg bw). Serum samples were subjected to amylase, lipase, transaminase, and interleukin-6 (IL-6) assays. The pancreas was excised to measure the levels of malondialdehyde, nitric oxide, catalase, superoxide dismutase, reduced glutathione, and glutathione peroxidase.
Pre- or post-treatment with L-lysine led to significant decreases in the levels of malondialdehyde and nitric oxide, while significant enhancement was observed in the activities of antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and glutathione (p < 0.001). However, the treatment potential of L-lysine was better as a protective agent than a therapeutic agent.
L-lysine treatment attenuates pancreatic tissue injury induced by L-arginine by inhibiting the release of the inflammatory cytokine IL-6 and enhance antioxidant activity. These effects may involve upregulation of anti-inflammatory factors and subsequent downregulation of IL6.
It has been known for approximately 30 years that large doses of the semi-essential basic amino acid L-arginine induce severe pancreatic inflammation in rats. Recently, it has been demonstrated that L-arginine can also induce pancreatitis in mice. Moreover, other basic amino acids like L-ornithine and L-lysine can cause exocrine pancreatic damage without affecting the endocrine parenchyma and the ducts in rats. The utilization of these noninvasive severe basic amino acid-induced pancreatitis models is becoming increasingly popular and appreciated as these models nicely reproduce most laboratory and morphological features of human pancreatitis. Consequently, the investigation of basic amino acid-induced pancreatitis may offer us a better understanding of the pathogenesis and possible treatment options of the human disease.Laboratory Investigation advance online publication, 23 December 2013; doi:10.1038/labinvest.2013.143.
Pancreatic acinar cells accumulate amino acids against a marked concentration gradient to synthesize digestive enzymes. Thus, the function of acinar cells depends on amino acid uptake mediated by active transport. Despite the importance of this process, pancreatic amino acid transporter expression and cellular localization is still unclear. We screened mouse pancreas for the expression of genes encoding amino acid transporters. We showed that the most highly expressed transporters, namely sodium dependent SNAT3 (Slc38a3) and SNAT5 (Slc38a5) and sodium independent neutral amino acids transporters LAT1 (Slc7a5) and LAT2 (Slc7a8), are expressed in the basolateral membrane of acinar cells. SNAT3 and SNAT5, LAT1 and LAT2 are expressed in acinar cells. Additional evidence that these transporters are expressed in mature acinar cells was gained using acinar cell culture and acute pancreatitis models. In the acute phase of pancreatic injury, when acinar cell loss occurs, and in an acinar cell culture model, which mimics changes occurring during pancreatitis, SNAT3 and SNAT5 are strongly down-regulated. LAT1 and LAT2 were down-regulated only in the in vitro model. At protein level, SNAT3 and SNAT5 expression was also reduced during pancreatitis. Expression of other amino acid transporters was also modified in both models of pancreatitis. The subset of transporters with differential expression patterns during acute pancreatitis might be involved in the injury/regeneration phases. Further expression, localization and functional studies will follow to better understand changes occurring during acute pancreatitis. These findings provide insight into pancreatic amino acid transport in healthy pancreas and during acute pancreatitis injury.
To investigate the influence of chronic pancreatitis (CP) on serum concentrations of amino acids.
Thirty-five male patients with alcoholic CP and 21 healthy male subjects were examined. Serum concentrations of amino acids were assayed by ion-pair high-performance liquid chromatography with mass detection.
Serum glutamate concentration was increased in CP patients as compared to controls. In contrast, serum concentrations of glutamine, histidine, tyrosine, proline, tryptophan and threonine were significantly decreased in CP patients. A trend towards decreasing concentrations of serum lysine, alanine, methionine and valine as well as for total serum amino acids was observed. The sum of aromatic and the sum of essential amino acid concentrations were significantly lower in CP patients than in controls.
CP leads to decreased serum concentrations of several amino acids, such as essential and aromatic serum amino acids, most likely due to decreased exocrine function.
We measured amino acid concentrations in plasma and skeletal muscle of three groups of patients with acute hemorrhagic pancreatitis: (a) patients without secondary organ lesions, (b) patients also suffering from kidney damage, and (c) patients in whom the pancreatitis was accompanied by sepsis and multiple organ failure. In all three groups, especially the third group, the amino acid concentrations in both plasma and muscle were below normal. Glutamine was only 14% of normal in muscle tissue of the third group. Onset of renal insufficiency was indicated by increasing values for 3-methylhistidine and cystathionine; multiple organ failure, by increased concentrations of methionine and phenylalanine in plasma. The low amino acid concentrations of patients with acute pancreatitis can be explained as a combined effect of semistarvation and hypercatabolism. Changes in the plasma concentrations of amino acids did not reflect necessarily the concentrations in muscle tissue.
Background
Around 20% of patients with acute pancreatitis (AP) will develop acute recurrent pancreatitis (ARP) and 10% will progress to chronic pancreatitis. While interventions to avoid recurrences exist for the two most common causes – abstinence for alcoholic and cholecystectomy for biliary pancreatitis – the are no known preventive measures in idiopathic ARP. Though it is not included in any of the guidelines, a low-fat diet is often recommended.
Our aim is to test dietary fat reduction's effect on AP recurrence in a randomized controlled setting, in order to provide high-quality evidence for the validity of such an intervention.
Methods, design
Participants with at least 2 episodes of AP in the preceding 2 years of which the last episode was idiopathic will be randomized to one of two diets with different fat contents: a ‘reduced fat diet’ (15% fat, 65% carbohydrate, 20% protein) and a ‘standard healthy diet’ (30% fat, 50% carbohydrate, 20% protein; based on WHO recommendations). Participants will be followed-up for 2 years (visits will be scheduled for months 3, 6, 12, 18 and 24) during which they will receive a repeated session of nutritional guidance, complete food frequency questionnaires and data on relapse, mortality, BMI, cardiovascular parameters and serum lipid values will be collected.
Discussion
This study will determine the effect of modifying the dietary fat content on AP recurrence, mortality, serum lipids and weight loss in idiopathic cases.
Objectives:
The objective of this study was to test whether pyruvate and glutamine affect the ethanol and cholecystokinin (CCK) effects on the mitochondrial function, viability, and morphology of rat pancreatic acini.
Methods:
Respiration was measured with Clark oxygen electrode. Mitochondrial membrane potential, reduced nicotinamide adenine dinucleotide (phosphate) (NAD(P)H), cell morphology, and viability were studied with fluorescence microscopy.
Results:
In vitro, CCK (0.1 nM) caused pyruvate-dependent stimulation of basal and uncoupled respiration, and the effects were abolished by ethanol (20 mM). The combination of ethanol with CCK (2 hours) caused necrosis of approximately 40% acinar cells in medium with glucose, but not with pyruvate and/or glutamine. Cholecystokinin (10 nM) or ethanol with 0.1 nM CCK caused plasma membrane blebbing not related to apoptosis only when both glutamine and pyruvate were present. Glutamine, but not pyruvate, decreased NAD(P)H level and prevented the effects of ethanol with CCK on mitochondrial membrane potential and NAD(P)H, but, in combination with CCK and ethanol, decreased the uncoupled respiration. In vivo, the combination of ethanol (4 g/kg) and CCK (20 pmol/kg) suppressed basal and uncoupled respiration and caused acinar cell blebbing, but not necrosis.
Conclusions:
The lack of sufficient substrate supply in vitro makes pancreatic acinar cells susceptible to necrosis caused by ethanol and CCK in clinically relevant concentrations.
The pancreas avidly takes up and synthesizes the amino acid asparagine (Asn), in part, to maintain an active translational machinery that requires incorporation of the amino acid. The de novo synthesis of Asn in the pancreas occurs through the enzyme asparagine synthetase (ASNS). The pancreas has the highest expression of ASNS of any organ, and it can further upregulate ASNS expression in the setting of amino acid depletion. ASNS expression is driven by an intricate feedback network within the integrated stress response (ISR), which includes the amino acid response (AAR) and the unfolded protein response (UPR). Asparaginase is a cancer chemotherapeutic drug that depletes plasma Asn. However, asparaginase-associated pancreatitis (AAP) is a major medical problem and could be related to pancreatic Asn depletion. In this review, we will provide an overview of ASNS and then describe its role in pancreatic health and in the exocrine disorders of pancreatitis and pancreatic cancer. We will offer the overarching perspective that a high abundance of ASNS expression is hardwired in the exocrine pancreas to buffer the high demands of Asn for pancreatic digestive enzyme protein synthesis, that perturbations in the ability to express or upregulate ASNS could tip the balance towards pancreatitis, and that pancreatic cancers exploit ASNS to gain a metabolic survival advantage.
Background
In severe acute pancreatitis (AP), intravenous glutamine has been shown to reduce the rate of complications, hospital stay, and mortality. In the present randomized trial, we aimed to evaluate the effect of enteral glutamine supplementation on clinical outcomes, gut permeability, systemic inflammation, oxidative stress, and plasma glutamine levels in patients with severe and predicted severe AP.
Methods
Patients with AP admitted within 72 h of onset of symptoms were included. The primary outcome measure was development of infected pancreatic and peri-pancreatic necrosis and in-hospital mortality. High-sensitivity C-reactive protein (HS-CRP) and interleukin-6 (IL-6) were evaluated as markers of inflammation; plasma thiobarbituric acid reactive substances (TBARS) and activities of serum superoxide dismutase and glutathione peroxidase were determined to evaluate oxidative stress; serum polyethylene glycol (PEG) was tested for intestinal permeability; subjective global assessment (SGA) was used for nutritional assessment, and an improvement in organ function was measured by the Modified Marshall score. Intention-to-treat analysis was used. A p-value of < 0.05 was considered statistically significant.
Results
After power calculation, we enrolled 18 patients in the glutamine and 22 in the control arm. There was no significant improvement in the development of infected necrosis and in-hospital mortality between the groups. Improvement in Modified Marshall score was observed in a higher proportion of patients receiving glutamine (15 [83.3%] vs. 12 [54.5%]; p = 0.05). Plasma glutamine levels improved more in glutamine-treated group (432.72 ± 307.83 vs. 618.06 ± 543.29 μM/L; p = 0.004), while it was lower in controls (576.90 ± 477.97 vs. 528.20 ± 410.45 μM/L; p = 0.003). PEG level was lower after glutamine supplementation (39.91 ± 11.97 vs. 32.30 ± 7.39 ng/mL; p = 0.02). Statistically significant reduction in IL-6 concentration was observed in the glutamine group at the end of treatment (87.44 ± 7.1 vs. 63.42 ± 33.7 μM/L; p = 0.02).
Conclusions
Despite absence of improvement in infected necrosis and in-hospital mortality, enteral glutamine supplementation showed improvement in gut permeability, oxidative stress, and a trend towards improvement in organ function as depicted by improvement in the Modified Marshall score.
Trial registration: NCT01503320 Open image in new window
Background
Dietary supplementation of arginine has been used by numerous world-class athletes and professional bodybuilders
over the past 30 years. l-Arginine indeed enhances muscular power and general performance via maintaining ATP
level. However, l-arginine is also known to induce acute pancreatitis in murine models.
Case report
We report the case of young man presenting with upper abdominal pain and increased serum lipase levels.
Contrast-enhanced computed tomography confirms a mild acute pancreatitis. Common etiologies have been ruled out and
toxicological anamnestic screening reveals the intake of protein powder. This is, to the best of our knowledge, the second
case in human of arginine-induced acute pancreatitis.
Conclusion
This case report suggests that every patient presenting with acute pancreatitis without obvious etiology should
be evaluated for the intake of toxics other than alcohol, including l-arginine.
Background & aims:
Little is known about the signaling pathways that initiate and promote acute pancreatitis (AP). The pathogenesis of AP has been associated with abnormal increases in cytosolic Ca(2+), mitochondrial dysfunction, impaired autophagy, and endoplasmic reticulum (ER) stress. We analyzed the mechanisms of these dysfunctions and their relationships, and how these contribute to development of AP in mice and rats.
Methods:
Pancreatitis was induced in C57BL/6J mice (control) and mice deficient in peptidylprolyl isomerase D (cyclophilin D, encoded by Ppid) by administration of L-arginine (also in rats), caerulein, bile acid, or an AP-inducing diet. Parameters of pancreatitis, mitochondrial function, autophagy, ER stress, and lipid metabolism were measured in pancreatic tissue, acinar cells, and isolated mitochondria. Some mice with AP were given trehalose to enhance autophagic efficiency. Human pancreatitis tissues were analyzed by immunofluorescence.
Results:
Mitochondrial dysfunction in pancreas of mice with AP was induced by either mitochondrial Ca(2+) overload or through a Ca(2+) overload-independent pathway that involved reduced activity of F-ATP synthase (80% inhibition in pancreatic mitochondria isolated from rats or mice given L-arginine). Both pathways were mediated by cyclophilin D and led to mitochondrial depolarization and fragmentation. Mitochondrial dysfunction caused pancreatic ER stress, impaired autophagy, and deregulation of lipid metabolism. These pathologic responses were abrogated in cyclophilin D-knockout mice. Administration of trehalose largely prevented trypsinogen activation, necrosis, and other parameters of pancreatic injury in mice with L-arginine AP. Tissues from patients with pancreatitis had markers of mitochondrial damage and impaired autophagy, compared with normal pancreas.
Conclusions:
In different animal models, we find a central role for mitochondrial dysfunction, and for impaired autophagy as its principal downstream effector, in development of AP. In particular, the pathway involving enhanced interaction of cyclophilin D with F-ATP synthase mediates L-arginine induced pancreatitis, a model of severe AP the pathogenesis of which has remained unknown. Strategies to restore mitochondrial and/or autophagic function might be developed for treatment of AP.
Goals:
To evaluate potential risk factors for the development of asparaginase-associated pancreatitis (AAP), we performed a systematic review of the current literature from January 1946 through May 2015.
Background:
Asparaginase, a primary treatment for the most common childhood cancer, acute lymphoblastic leukemia (ALL), is a well-described cause of pancreatitis. Further, pancreatitis is among the most burdensome and common complications of asparaginase treatment and represents a major reason for early-drug termination and inferior outcomes. The literature lacks clarity about the risk factors for AAP, and this knowledge gap has hampered the ability to reliably predict which patients are likely to develop AAP.
Study:
In an expansive screen, 1842 citations were funneled into a review of 59 full articles, of which 10 were deemed eligible based on predetermined inclusion criteria.
Results:
Of the 10 identified studies, only 2 studies showed that children above 10 years of age had a >2-fold risk of AAP compared with younger children. Patients placed in high-risk ALL categories had a greater incidence of pancreatitis in 2 studies. In addition, use of pegylated asparaginase resulted in a higher incidence of AAP in 1 study.
Conclusions:
In this systematic review, older age, asparaginase formulation, higher ALL risk stratification, and higher asparaginase dosing appear to play a limited role in the development of AAP. Further studies are needed to probe the underlying mechanisms contributing to the development of pancreatitis in patients receiving asparaginase.
Pyruvate transport across the inner mitochondrial membrane is believed to be a prerequisite for gluconeogenesis in hepatocytes, which is important for the maintenance of normoglycemia during prolonged food deprivation but also contributes to hyperglycemia in diabetes. To determine the requirement for mitochondrial pyruvate import in gluconeogenesis, mice with liver-specific deletion of mitochondrial pyruvate carrier 2 (LS-Mpc2(-/-)) were generated. Loss of MPC2 impaired, but did not completely abolish, hepatocyte conversion of labeled pyruvate to TCA cycle intermediates and glucose. Unbiased metabolomic analyses of livers from fasted LS-Mpc2(-/-) mice suggested that alterations in amino acid metabolism, including pyruvate-alanine cycling, might compensate for the loss of MPC2. Indeed, inhibition of pyruvate-alanine transamination further reduced mitochondrial pyruvate metabolism and glucose production by LS-Mpc2(-/-) hepatocytes. These data demonstrate an important role for MPC2 in controlling hepatic gluconeogenesis and illuminate a compensatory mechanism for circumventing a block in mitochondrial pyruvate import.
AIM: To evaluate the therapeutic effect of alanyl-glutamine dipeptide (AGD) in the treatment of severe acute pancreatitis (SAP) in early and advanced stage.
METHODS: Eighty patients with SAP were randomized and received 100 mL/d of 20% AGD intravenously for 10 d starting either on the day of (early treatment group) or 5 d after (late treatment group) admission. Groups had similar demographics, underlying diseases, Ranson score, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and Balthazar’s computed tomography (CT) score at the beginning of the study and underwent similar other medical and nutritional management.
RESULTS: The duration of acute respiratory distress syndrome (2.7 ± 3.3 d vs 12.7 ± 21.0 d, P < 0.01), renal failure (1.3 ± 0.5 d vs 5.3 ± 7.3 d, P < 0.01), acute hepatitis (3.2 ± 2.3 d vs 7.0 ± 7.1 d, P < 0.01), shock (1.7 ± 0.4 d vs 4.8 ± 3.1 d, P < 0.05), encephalopathy (2.3 ± 1.9 d vs 9.5 ± 11.0 d, P < 0.01) and enteroparalysis (2.2 ± 1.4 d vs 3.5 ± 2.2 d, P < 0.01) and hospital stay (28.8 ± 9.4 d vs 45.2 ± 27.1 d, P < 0.01) were shorter in the early treatment group than in the late treatment group. The 15-d APACHE II score was lower in the early treatment group than in the late treatment group (5.0 ± 2.4 vs 8.6 ± 3.6, P < 0.01). The infection rate (7.9% vs 26.3%, P < 0.05), operation rate (13.2% vs 34.2%, P < 0.05) and mortality (5.3% vs 21.1%, P < 0.05) in the early treatment group were lower than in the late treatment group.
CONCLUSION: Early treatment with AGD achieved a better clinical outcome in SAP patients.
Creatine is an important molecule involved in cellular energy metabolism. Creatine is spontaneously converted to creatinine at a rate of 1·7 % per d; creatinine is lost in the urine. Creatine can be obtained from the diet or synthesised from endogenous amino acids via the enzymes arginine:glycine amidinotransferase (AGAT) and guanidinoacetate N-methyltransferase (GAMT). The liver has high GAMT activity and the kidney has high AGAT activity. Although the pancreas has both AGAT and GAMT activities, its possible role in creatine synthesis has not been characterised. In the present study, we examined the enzymes involved in creatine synthesis in the pancreas as well as the synthesis of guanidinoacetate (GAA) and creatine by isolated pancreatic acini. We found significant AGAT activity and somewhat lower GAMT activity in the pancreas and that pancreatic acini had measurable activities of both AGAT and GAMT and the capacity to synthesise GAA and creatine from amino acids. Creatine supplementation led to a decrease in AGAT activity in the pancreas, though it did not affect its mRNA or protein abundance. This was in contrast with the reduction of AGAT activity and mRNA and protein abundance in the kidney, suggesting that the regulatory mechanisms that control the expression of this enzyme in the pancreas are different from those in the kidney. Dietary creatine increased the concentrations of GAA, creatine and phosphocreatine in the pancreas. Unexpectedly, creatine supplementation decreased the concentrations of S-adenosylmethionine, while those of S-adenosylhomocysteine were not altered significantly.
Aims:
Our aim was to investigate plasma amino acid levels in chronic pancreatitis (CP) patients and examine their relationship with exocrine insufficiency.
Methods:
Thirty-nine patients with alcoholic CP and 20 healthy controls were examined. CP patients were divided into an exocrine normal group (n = 28) and an exocrine insufficiency group (n = 11). Selected clinical and laboratory values were compared among the three groups, and the effect of an elemental diet was observed in 6 patients of the exocrine insufficiency group.
Results:
Total amino acid concentration was significantly higher in the control group than in the exocrine normal group and exocrine insufficiency group (p = 0.032, p = 0.020). In the exocrine insufficiency group, significant reductions in the concentrations of serum histidine and methionine were found compared with the control group and exocrine normal group (histidine: p = 0.032, p = 0.045; methionine: p = 0.043, p = 0.049). In the exocrine normal group and exocrine insufficiency group, significant elevation in the concentration of serum glutamate was found compared with the control group (p = 0.036, p = 0.029). Elemental diet improved these amino acid concentrations.
Conclusion:
Patients with CP exhibit alterations in the levels of several amino acids, such as histidine, methionine, and glutamate. These amino acid deficiencies seem to correlate with exocrine insufficiency and be improved by an elemental diet.
Mitochondria maintain numerous energy-consuming processes in pancreatic acinar cells, yet characteristics of pancreatic mitochondrial oxidative phosphorylation in native conditions are poorly studied. Besides, it is not known which type of solution is most adequate to preserve functions of pancreatic mitochondria in situ. Here we propose a novel experimental protocol suitable for in situ analysis of pancreatic mitochondria metabolic states. Isolated rat pancreatic acini were permeabilized with low doses of digitonin. Different metabolic states of mitochondria were examined in KCl- and sucrose-based solutions using Clark oxygen electrode. Respiration of digitonin-treated, unlike of intact, acini was substantially intensified by succinate or mixture of pyruvate plus malate. Substrate-stimulated respiration rate did not depend on solution composition. In sucrose-based solution, oligomycin inhibited State 3 respiration at succinate oxidation by 65.4% and at pyruvate plus malate oxidation by 60.2%, whereas in KCl-based solution, by 32.0% and 36.1%, respectively. Apparent respiratory control indices were considerably higher in sucrose-based solution. Rotenone or thenoyltrifluoroacetone severely inhibited respiration, stimulated by pyruvate plus malate or succinate, respectively. This revealed low levels of non-mitochondrial oxygen consumption of permeabilized acinar cells. These results suggest a stronger coupling between respiration and oxidative phosphorylation in sucrose-based solution. Copyright © 2012 John Wiley & Sons, Ltd.
Propionic acidemia (PA) is a rare organic acidemia that is due to deficiency in the enzyme propionyl-coA carboxylase. Complications are currently described mostly in the form of case reports. We sampled a population of affected individuals in order to estimate the frequency of complications amongst the sample. The study is a cross-sectional retrospective review with a survey instrument and recruitment through the Propionic Acidemia Foundation. Responses for 58 individuals were tabulated for each question as how frequently the complication was reported among responders. Commonly reported findings included seizures, arrhythmia, leucopenia, and anemia. Developmental and cognitive disabilities were reported in the majority of individuals. Heart failure or cardiomyopathy was reported in over half of deceased individuals at time of death. Pancreatitis was reported in a minority of the sample, yet more than half of these reported a recurrence. These results update and extend our current knowledge of recognized complications among individuals with PA. The results also provide new information regarding developmental outcomes and previously unreported morbidity from cardiac and gastrointestinal complications. Longitudinal studies exploring associated biochemical and clinical parameters are necessary to further our understanding of the pathophysiology of PA and its complications.
Aims:
Large doses of intraperitoneally injected basic amino acids, L-arginine, or L-ornithine, induce acute pancreatitis in rodents, although the mechanisms mediating pancreatic toxicity remain unknown. Another basic amino acid, L-lysine, was also shown to cause pancreatic acinar cell injury. The aim of the study was to get insight into the mechanisms through which L-lysine damages the rat exocrine pancreas, in particular to characterize the kinetics of L-lysine-induced mitochondrial injury, as well as the pathologic responses (including alteration of antioxidant systems) characteristic of acute pancreatitis.
Results:
We showed that intraperitoneal administration of 2 g/kg L-lysine induced severe acute necrotizing pancreatitis. L-lysine administration caused early pancreatic mitochondrial damage that preceded the activation of trypsinogen and the proinflammatory transcription factor nuclear factor-κB (NF-κB), which are commonly thought to play an important role in the development of acute pancreatitis. Our data demonstrate that L-lysine impairs adenosine triphosphate synthase activity of isolated pancreatic, but not liver, mitochondria.
Innovation and conclusion:
Taken together, early mitochondrial injury caused by large doses of L-lysine may lead to the development of acute pancreatitis independently of pancreatic trypsinogen and NF-κB activation.
Accumulating evidence suggests that the amino acid glutamate (Glu) may play a role in mediating immune function. The demonstration of Glu receptors (GluR) and Glu transporters (GluT) on a variety of immune cells suggests that Glu has a functional role in immunoregulation well beyond its role as a neurotransmitter. The extracellular Glu concentration plays a key role in the regulation of GSH synthesis in immune cells via 2 key GluTs (i.e., Xc- and X-AG systems). Emerging evidence also suggests a role of Glu as signaling molecule in immune cells via ionotropic GluRs (iGluRs) and metabotropic GluRs (mGluRs). In vitro, extracellular Glu concentration has been shown to exert a dose-dependent regulation on lymphocyte activation/proliferation. Specifically, Given the exceedingly high intestinal Glu concentration, these finding are suggestive of a potential role for Glu in modulating immune function and promoting tolerance in the gut associated lymphoid tissues.
Ammonia is a major neurotoxin implicated in hepatic encephalopathy (HE). Here we discuss evidence that many aspects of ammonia toxicity in HE-affected brain are mediated by glutamine (Gln), synthesized in excess from ammonia and glutamate by glutamine synthetase (GS), an astrocytic enzyme. The degree to which Gln is increased in brains of patients with HE was found to positively correlate with the grade of HE. In animals with HE, a GS inhibitor, methionine sulfoximine (MSO), reversed a spectrum of manifestations of ammonia toxicity, including brain edema and increased intracranial pressure, even though MSO itself increased brain ammonia levels. MSO inhibited, while incubation with Gln reproduced the oxidative stress and cell swelling observed in ammonia-exposed cultured astrocytes. Recent studies have shown that astrocytes swell subsequent to Gln transport into mitochondria and its degradation back to ammonia, which then generates reactive oxygen species and the mitochondrial permeability transition. This sequence of events led to the formulation of the "Trojan Horse" hypothesis. Further verification of the role of Gln in the pathogenesis of HE will have to account for: (1) modification of the effects of Gln by interaction of astrocytes with other CNS cells; and (2) direct effects of Gln on these cells. Recent studies have demonstrated a "Trojan Horse"-like effect of Gln in microglia, as well as an interference by Gln with the activation of the NMDA/NO/cGMP pathway by ammonia as measured in whole brain, a process that likely also involves neurons.
The chemical decomposition of glutamine to ammonia and pyrrolidonecarboxylic acid was studied at 37 degrees C in a pH range of 6.8-7.8 in different media preparations containing various amounts of fetal bovine serum. The media type influenced the decomposition rate, and the first-order rate constants increased with increasing pH values. The serum concentration had little or no effect on the decomposition rate. The importance of chemical decomposition of glutamine on the analysis of glutamine and ammonia metabolism was illustrated by an example of batch cultivation of a hybridoma cell line. The difference between the apparent uptake rate of glutamine and the actual uptake rate (which is corrected for the chemical decomposition) is shown to be as high as 200%. Similar discrepancy between the apparent and actual ammonia production rate is observed. Mathematical analysis was carried out to develop the relationship between the apparent and actual glutamine uptake and ammonia production rates. The analysis reveals that there are three important dimensionless parameter ratios that govern the difference between the apparent and actual glutamine uptake and ammonia production rates.
1. For the first time utilization of intravenously administered l-alanyl-l-glutamine and glycyl-l-tyrosine was investigated by means of their kinetic behaviour after bolus injection in 10 and 11 apparently healthy male subjects (age 26.6 ± 5.7 years), respectively.
2. The injection of the synthetic dipeptides was not accompanied by any side effects or complaints.
3. The synthetic dipeptides l-alanyl-l-glutamine and glycyl-l-tyrosine were rapidly cleared from plasma. By applying a monoexponential model the elimination half-lives were found to have very similar values (3.8 ± 0.5 and 3.4 ± 0.3 min) whether alanine or glycine was occupying the N-terminal position. The estimated volume of distribution was approximately that of the extracellular space.
4. Peptide disappearance was accompanied by a prompt equimolar increase in the concentrations of the constituent amino acids alanine and glutamine as well as glycine and tyrosine.
5. The study provides firm evidence that l-alanyl-l-glutamine and glycyl-l-tyrosine are rapidly (quantitatively) hydrolysed. The results of this study may indicate a safe and efficient parenteral use of the investigated peptides as sources of free glutamine and free tyrosine.
The uptake and oxidation of L-alanine and L-leucine as well as the oxidation of D-glucose were studied in pieces of microdissected exocrine mouse pancreas. The main observations and conclusions were as follows. The rate of oxidation of D-glucose was low and was only slightly enhanced by increasing its concentration in the medium from 3 to 20 mM. Even at a concentration as low as 0.1 mM, both amino acids were oxidized at a higher rate than D-glucose. Thus, mouse exocrine pancreas seems to prefer amino acids to D-glucose as substrate for its energy metabolism. The uptake of L-alanine and L-leucine in the exocrine cells was studied with a double-label technique using 14C-L-glucose as an extracellular marker. Both amino acids were rapidly taken up and accumulated in the exocrine cells. D-glucose inhibited both the uptake and oxidation of L-alanine. The decreased rate of oxidation of this amino acid might have been due to the reduction in uptake. Stimulation of secretion by cholecystokinin-pancreozymin increased the oxidation of D-glucose, L-alanine and L-leucine. However, no effect on the transport of the amino acids into the exocrine cells was observed. Therefore the effect of CCK-PZ on oxidation seems not to depend on an increased uptake of the amino acids. The presence of insulin (100 /<g/ml) stimulated the oxidation of D-glucose, but not that of the amino acids. Insulin had no effect on the transport of the amino acids into the exocrine cells.
Lysinuric protein intolerance is an autosomal recessive disease caused by defective transport of cationic amino acids. Of the 38 lysinuric protein intolerance patients diagnosed in Finland since 1965, four pediatric patients have died. We describe the clinical courses and autopsy findings for these patients. All patients developed acute respiratory insufficiency. In addition to pulmonary hemorrhages, three of the patients had pulmonary alveolar proteinosis and one had cholesterol granulomas. Three patients had a clinically obvious renal insufficiency, but all four showed histologic signs of immune complex-mediated glomerulonephritis. The patients also developed hepatic insufficiency with fatty degeneration or cirrhosis. All patients showed anemia, thrombocytopenia, and a severe bleeding tendency. The bone marrow of three patients was hypercellular, but the amount of megakaryocytes was decreased in two cases. Amyloid was present in the lymph nodes and the spleen. Bone specimens showed osteoporosis. We conclude that pediatric patients with lysinuric protein intolerance are predisposed to develop pulmonary alveolar proteinosis and glomerulonephritis. They are also at risk of protein malnutrition in the active growth phase, probably due to higher requirements for total nitrogen and amino acids.
The aim of this study was to determine the metabolism and the tolerance of a new amino acid (AA) solution administered under conditions mimicking cyclical parenteral nutrition (PN) in humans. Eight healthy volunteers received peripheral PN for 10 h providing 10.5 mg N x kg(-1) x h(-1) and 2.0 kcal x kg(-1) x h(-1) (glucose-to-lipids ratio: 70/30%). For adaptation, a non-protein energy intake was increased progressively for 90 min; thereafter, AA infusion was started and maintained at a constant rate for 10 h. Plasma and urine concentrations of all the AAs were measured before, during and after the PN. For each given AA, the relation between plasma variations at the steady-state and infusion rate, plasma clearance (Cl), renal clearance (Clr), re-absorption rate (Reab) and, retention rate (Reten) were determined. The nitrogen balance (DeltaN) was calculated during the PN period. The results are presented as means+/-sem. All plasma AA concentrations decreased during the starting period of non-protein energy intake. The plasma AA concentrations reached a steady-state within 3 h upon AA infusion, except for glycine and lysine (6 h). At the steady state, the plasma concentrations of the infused AAs were closely correlated to their infusion rate (y= -18.3+1.5x, r(2)=0.92). The plasma glutamine concentration was maintained during the PN, which indicates that the solution might stimulate the de novo synthesis of this AA. When the PN was stopped, plasma levels of the AAs decreased, most of them returning to their basal levels, or significantly below for lysine (P<0.05), alanine (P<0.05), proline (P<0.01) and glutamine (P<0.05). No volunteer showed any adverse effect during the infusion period. DeltaN was: 0.8+/-0.5 gN/10 h. Metabolic characteristics for essential AAs were: Cl<0.5 l min(-1), Clr <1.5 ml x min(-1) Reab >or= 99%, Reten >or=99% and for non-essential AAs: Cl <0.6 l x min(-1) except aspartate (2.8+/-0.3 l x min(-1)), Clr < 3 ml x min(-1) except glycine (6.8+/-0.7), aspartate (8.2+/-3.5) and histidine (8.8+/-1.3); Reab >or= 98% except glycine (95+/-1), aspartate (94+/-2) and histidine (94+/-1), Reten >or=97% except histidine (94+/-1), glycine (95+/-3). These results indicate that in healthy subjects, the amounts of AAs provided by the new solution were well balanced for an intravenous administration, and so were well utilized without excessive urinary excretion. The present study provides useful metabolic parameters for a further evaluation in disease.
Administration of high doses of amino acids like ethionine, methionine, and arginine causes pancreatic tissue damage. The initial mechanism behind these effects is not known. The aim of this study was to show the early effects of a load of L-arginine on programed cell death/proliferation and ATP levels in the pancreas.
We analyzed in rats the effects of intraperitoneal administration of L-arginine on serum amino acids, pancreatic cell apoptosis/proliferation, and ATP levels at 8, 16, and 24 hours. Serum amino acid concentrations were measured with HPLC, tissue ATP was measured fluorometrically, apoptosis was studied with caspase-3 activity and histone-associated DNA-fragments, and proliferation was studied with thymidine autoradiography.
After a load of l-arginine, there were initially increased serum levels of L-arginine and L-citrulline, but these fell below control levels after 24 hours as well as amino acids in the glutamate family (ornithine, proline, histidine, and glutamine). Initially, increased ATP levels in the pancreatic tissue returned to control levels at 24 hours. The acinar cells proliferation was suppressed and the apoptosis rate strongly increased at 16 and 24 hours. Pancreatic histology showed vacuole formation in the acinar cells at 8 hours. At 16 hours, there was less vacuolization, but apoptotic bodies were seen, and at 24 hours there was cell degeneration but no necrosis.
After a load of l-arginine, amino acid metabolism causes a high ATP production in the pancreatic tissue that may cause mitochondrial initiation of cell death.
To investigate the role of glutamine on splanchnic blood flow, apoptosis of pancreatic acinar and the underlying mechanism in rats with severe acute pancreatitis.
Forty-eight rats were randomized into two groups: the glutamine group (n = 24) and the severe acute pancreatitis group (n = 24). Jejunotomy was performed in all rats: the glutamine group also received glutamine, and the severe acute pancreatitis group received normal saline. Each group was then subdivided into three subgroups of eight rats each, with the rats be killed at 12, 24 and 36 h after the operation, respectively. A control group underwent sham operation (n = 8). The regional pancreatic microvascular blood flow was measured by Doppler ultrasound. The blood flow of the portal vein, splenic artery and superior mesenteric artery were also recorded. Apoptosis of pancreatic acinar cells was evaluated by TUNEL method.
The regional pancreatic microvascular blood flow (KHz) decreased significantly in the severe acute pancreatitis group (P < 0.01), and continued to decrease after 24 h (vs. 12 h, P < 0.01). The blood flow of the portal vein, splenic artery and superior mesenteric artery also decreased in the severe acute pancreatitis group. The glutamine group showed increased regional pancreatic microvascular blood flows, as well as increased blood flow of the portal vein, splenic artery and superior mesenteric artery (vs. the severe acute pancreatitis group, P < 0.01). The apoptotic index of pancreatic acinar in the glutamine group was higher than in the severe acute pancreatitis group (P < 0.01), and both were much higher than that in the control group (P < 0.01).
Enteral administration of glutamine increased the splanchnic blood flow in severe acute pancreatitis rats. The apoptotic index of pancreatic acinar was negatively correlated with the severity of the disease. The interrelation between glutamine and apoptosis in severe acute pancreatitis is worthy of further investigation.
Patients in the early phase of acute pancreatitis (AP) have reduced serum levels of arginine and citrulline. This may be of patho-biological importance, since arginine is the substrate for nitric oxide, which in turn is involved in normal pancreatic physiology and in the inflammatory process. Serum amino acid spectrum was measured daily for five days and after recovery six weeks later in 19 patients admitted to the hospital for acute pancreatitis. These patients had abnormal levels of most amino acids including arginine, citrulline, glutamine and glutamate. Phenylalanine and glutamate were increased, while arginine, citrulline, ornithine and glutamine were decreased compared to levels after recovery. NO(2)/NO(3) concentration in the urine, but not serum arginase activity, was significantly increased day 1 compared to day 5 after admission. Acute pancreatitis causes a disturbance of the serum amino acid spectrum, with possible implications for the inflammatory process and organ function both in the pancreas and the gut. Supplementation of selected amino acids could possibly be of value in this severe condition.
Intraperitoneal administration of large doses of L-arginine is known to induce severe acute pancreatitis in rats. We therefore set out to determine whether metabolites of L-arginine (L-ornithine, L-citrulline, and nitric oxide) cause pancreatitis.
The authors conducted an in vivo animal study.
This study was conducted at a university research laboratory.
Study subjects were male Wistar rats.
Dose-response and time course changes of laboratory and histologic parameters of pancreatitis were determined after L-arginine, L-ornithine, L-citrulline, or sodium nitroprusside (nitric oxide donor) injection.
Intraperitoneal injection of 3 g/kg L-ornithine but not L-citrulline or nitroprusside caused severe acute pancreatitis; 4 to 6 g/kg L-ornithine killed the animals within hours. Serum and ascitic amylase activities were significantly increased, whereas pancreatic amylase activity was decreased after intraperitoneal injection of 3 g/kg L-ornithine. The increase in pancreatic trypsin activity (9-48 hrs) correlated with the degradation of IkappaB proteins and elevated interleukin-1beta levels. Oxidative stress in the pancreas was evident from 6 hrs; HSP72 synthesis was increased from 4 hrs after L-ornithine administration. Morphologic examination of the pancreas showed massive interstitial edema, apoptosis, and necrosis of acinar cells and infiltration of neutrophil granulocytes and monocytes 18 to 36 hrs after 3 g/kg L-ornithine injection. One month after L-ornithine injection, the pancreas appeared almost normal; the destructed parenchyma was partly replaced by fat. Equimolar administration of L-arginine resulted in lower pancreatic weight/body weight ratio, pancreatic myeloperoxidase activity, and histologic damage compared with the L-ornithine-treated group. L-ornithine levels in the blood were increased 54-fold after intraperitoneal administration of L-arginine.
We have developed a simple, noninvasive model of acute necrotizing pancreatitis in rats by intraperitoneal injection of 3 g/kg L-ornithine. Interestingly, we found that, compared with L-arginine, L-ornithine was even more effective at inducing pancreatitis. Large doses of L-arginine produce a toxic effect on the pancreas, at least in part, through L-ornithine.
Citrin deficiency caused by SLC25A13 gene mutations develops into adult-onset type II citrullinemia (CTLN2) and may be accompanied with hepatic steatosis and steatohepatitis. As its clinical features remain unclear, we aimed to explore the characteristics of fatty liver disease associated with citrin deficiency.
The prevalence of hepatic steatosis in 19 CTLN2 patients was examined, and clinical features were compared with those of non-alcoholic fatty liver disease (NAFLD) patients without known SLC25A13 gene mutations.
Seventeen (89%) CTLN2 patients had steatosis, and 4 (21%) had been diagnosed as having NAFLD before appearance of neuropsychological symptoms. One patient had steatohepatitis. Citrin deficiency-associated fatty livers showed a considerably lower prevalence of accompanying obesity and metabolic syndrome, higher prevalence of history of pancreatitis, and higher serum levels of pancreatic secretory trypsin inhibitor (PSTI) than fatty livers without the mutations. Receiver operating characteristic curve analyses revealed that a body mass index < 20kg/m(2) and serum PSTI>29ng/mL were associated with citrin deficiency.
Patients presenting with non-alcoholic fatty liver unrelated to obesity and metabolic syndrome might have citrin deficiency, and serum PSTI may be a useful indicator for distinguishing this from conventional NAFLD.