Serum Amino Acid Levels Research Articles

PP01.1 – 2565: Next generation sequencing analysis in neonatal/early epileptic encephalopathy

Objective Epileptic encephalopathy (EE) term describes epilepsy syndromes in which seizures and epileptiform electroencephalographic abnormalities are considered to contribute to progressive cerebral dysfunction. A subset of all the EEs that still await an etiological explanation, particularly those with onset of seizures within the first year of life. In this study genetic backround of neonatal/early infantile EE was investigated by next generation sequencing (NGS) analysis. Methods Thirty cases who had refractory seizures with neonatal or early infantile onset were prospectively included in this study. Three cases had history of hospitalization in neonatal unit due to meconium aspiration syndrome, and four cases also had cyanosis and/or transient respiratory distress following the labor. All cases had normal metabolic work up including serum lactic acid, pyruvic acid, aminoacid and carnitine levels, biotinidase activity and urine organic acids. Their cranial magnetic resonance imaging findings were normal except cerebral atrophy. Their karyotype analyses were normal. None of them had antiquitin gene mutation. Mutations in 16 genes (ARX, CDKL5, CNTNAP2, FOLR1, FOXG1, GRPR, LAMC3, MBD5, MECP2, PCDH19, PNKP, SCN1A, SCN1B, SCN2A, STXBP1, KCNQ2) were examined with NGS method in our cases. Results Ages ranged between 6–204 (62.5±51.6) months. Parental consanguinity was found in 11 of 30 cases (36%). Seizures started between 1–270 (91.7±80.25) days of life, eleven cases had seizures with neonatal onset. Infantile spasms were the predominant seizure type in our group consisting of 16 of 30 cases. All of them were treated with at least two anticonvulsant drugs. Cranial magnetic resonance imaging was normal in half of the cases, the reminder had cortical or cerebellar atrophy. The results of NGS analysis were discussed with the literature. Conclusion We believe that NGS screening will soon contribute to pediatric neurologists to diagnose children with epilepsies of unknown etiology.

Essential amino acids in the gluten-free diet and serum in relation to depression in patients with celiac disease.

IntroductionCeliac disease (CD) is associated with an increased risk of major depressive disorder, possibly due to deficiencies in micronutrients in the gluten-free diet. We aimed to investigate whether essential amino acids (i.e., the precursors of serotonin, dopamine and other neurotransmitters) are depleted in the diet and serum of CD patients with major depressive disorder.MethodsIn a cross-sectional study we assessed dietary intake of amino acids and serum levels of amino acids, in 77 CD patients on a gluten-free diet and in 33 healthy controls. Major depressive disorder was assessed with structured interviews (using the Mini International Neuropsychiatric Interview Plus). Dietary intake was assessed using a 203-item food frequency questionnaire.ResultsParticipants had a mean age of 55 years and 74% were women. The intake of vegetable protein was significantly lower in CD patients than in healthy controls (mean difference of 7.8 g/d; 95% CI: 4.7–10.8), as were serum concentrations of tyrosine, phenylalanine and tryptophan (all p < 0.005). However, within the CD patient group, the presence of major depressive disorder (n = 42) was not associated with intake or serum levels of essential amino acids.ConclusionsPatients with CD on a long-term gluten-free diet, with good adherence, consume significantly less vegetable protein than controls, and their serum levels of several essential amino acids were also lower. Despite its potential adverse effect, intake and serum levels of essential amino acids were not related to major depression.

Elevated serum levels of cysteine and tyrosine: early biomarkers in asymptomatic adults at increased risk of developing metabolic syndrome.

As there is effective intervention for delaying or preventing metabolic diseases, which are often present for years before becoming clinically apparent, novel biomarkers that would mark metabolic complications before the onset of metabolic disease should be identified. We investigated the role of fasting serum amino acids and their associations with inflammatory markers, adipokines, and metabolic syndrome (MetS) components in subjects prior to the onset of insulin resistance (IR). Anthropometric measurements, food records, adipokines, biochemical markers, and serum levels of amino acids were determined in 96 asymptomatic subjects aged 25–49 years divided into three groups according to the number of MetS components present. Cysteine and tyrosine were significantly higher already in group with one component of MetS present compared to subjects without MetS components. Serum amino acid levels correlated with markers of inflammation and adipokines. Alanine and glycine explained 10% of insulin resistance variability. The role of tyrosine and cysteine, that were higher already with 1 component of MetS present, should be further investigated as they might point to future insulin disturbances.

Gene expression, serum amino acid levels, and growth performance of pigs fed dietary leucine and lysine at different ratios.

We examined 96 pigs (28.1 ± 0.83 kg) to analyze the effect of Leu:Lys ratios on expression of the cationic amino acid transporters b(0,+) and CAT-1 in the jejunum and liver as well as myosin expression in 2 muscles to estimate the optimum standardized ileal digestible (SID) Leu:Lys ratio for growth rate and efficiency. A wheat-and wheat bran-based diets were formulated to meet the requirements of SID amino acids other than Leu (0.70%) and Lys (0.80%). L-Leu was added to the basal diet in 5 SID Leu:Lys ratios (88, 100, 120, 140, and 160% in diets 1-5). Tissue samples were collected from 8 pigs with ratios of 88, 120, and 160%. Relative expression of b(0,+), CAT-1, and myosin was analyzed. b(0,+) expression in the jejunum was higher but lower in the liver of pigs with the 120% ratio compared to those with the 88 or 160% ratio; myosin expression in longissimus dorsi was also higher in pigs with the 120% ratio (P < 0.05). CAT-1 was lower in the jejunum and longissimus dorsi of pigs with 120 or 160% ratios than in pigs with 88%. Serum concentration of nearly all amino acids decreased with excess dietary Leu (P < 0.05). The SID Leu:Lys of 104 and 109% optimized average daily gain and feed conversion ratio, respectively. Thus, the dietary Leu:Lys ratio affects the expression of genes coding for amino acid transporters and myosin, the availability of Lys, and the growth rate and efficiency in pigs.

Markers of glutamate signaling in cerebrospinal fluid and serum from patients with bipolar disorder and healthy controls

Glutamate is the major excitatory neurotransmitter in the brain. Aberrations in glutamate signaling have been linked to the pathophysiology of mood disorders. Increased plasma levels of glutamate as well as higher glutamine+glutamate levels in the brain have been demonstrated in patients with bipolar disorder as compared to healthy controls. In this study, we explored the glutamate hypothesis of bipolar disorder by examining peripheral and central levels of amino acids related to glutamate signaling. A total of 215 patients with bipolar disorder and 112 healthy controls from the Swedish St. Göran bipolar project were included in this study. Glutamate, glutamine, glycine, l-serine and d-serine levels were determined in serum and in cerebrospinal fluid using high performance liquid chromatography with fluorescence detection. Serum levels of glutamine, glycine and d-serine were significantly higher whereas l-serine levels were lower in patients with bipolar disorder as compared to controls. No differences between the patient and control group in amino acid levels were observed in cerebrospinal fluid. The observed differences in serum amino acid levels may be interpreted as a systemic aberration in amino acid metabolism that affects several amino acids related to glutamate signaling.

Phenylalanine sensitive K562-D cells for the analysis of the biochemical impact of excess amino acid.

Although it is recognized that the abnormal accumulation of amino acid is a cause of the symptoms in metabolic disease such as phenylketonuria (PKU), the relationship between disease severity and serum amino acid levels is not well understood due to the lack of experimental model. Here, we present a novel in vitro cellular model using K562-D cells that proliferate slowly in the presence of excessive amount of phenylalanine within the clinically observed range, but not phenylpyruvate. The increased expression of the L-type amino acid transporter (LAT2) and its adapter protein 4F2 heavy chain appeared to be responsible for the higher sensitivity to phenylalanine in K562-D cells. Supplementation with valine over phenylalanine effectively restored cell proliferation, although other amino acids did not improve K562-D cell proliferation over phenylalanine. Biochemical analysis revealed mammalian target of rapamycin complex (mTORC) as a terminal target of phenylalanine in K562-D cell proliferation, and supplementation of valine restored mTORC1 activity. Our results show that K562-D cell can be a potent tool for the investigation of PKU at the molecular level and to explore new therapeutic approaches to the disease.

Tumor-dependent increase of serum amino acid levels in breast cancer patients has diagnostic potential and correlates with molecular tumor subtypes

BackgroundMalignancies induce changes in the levels of serum amino acids (AA), which may offer diagnostic potential. Furthermore, changes in AA levels are associated with immune cell function. In this study, serum AA levels were studied in breast cancer patients versus patients with benign breast lesions.MethodsIn a prospective study, serum levels of 15 AA were measured by high performance liquid chromatography before and after surgery in 41 breast cancer patients (BrCA) and nine patients with benign breast lesions (healthy donors, HD). Results were analyzed in relation to clinical tumor data and tested against immunological flow cytometry data. Principal component analysis was performed and the accuracy of AA levels as a potential diagnostic tool was tested.ResultsPre- but not postoperative serum AA levels were increased in BrCA in eight out of 15 AA compared with HD. Serum AA levels were highest in the most aggressive (basal-like) as compared with the least aggressive tumor subtype (luminal A). A principal component (PC1) of all measured AA correlated with a mainly pro-inflammatory immune profile, while a second one (PC2, selectively considering AA preoperatively differing between HD and BrCA) could predict health state with an area under the curve of 0.870.ConclusionsBreast cancer shows a tumor-dependent impact on serum AA levels, which varies with intrinsic tumor subtypes and is associated with a pro-inflammatory state. Serum AA levels need further evaluation as a potential diagnostic tool.

Allosteric regulation of the calcium-sensing receptor in obese individuals

We have previously reported that the calcium-sensing receptor (CaSR) plays an important role in modulating lipid metabolism under low calcium conditions. The aim of this study was to identify possible regulators of CaSR and the mechanisms of action of CaSR in obese individuals. Subcutaneous fat samples were obtained from 10 obese and 10 non-obese males undergoing elective abdominal surgery. Visceral fat pads were obtained from 12 obese and 12 non-obese male rats. Serum lipid, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) concentrations, as well as the gene and protein expression of CaSR in the white adipose tissue of obese subjects and rats were determined. Serum total calcium, vitamin D, parathyroid hormone (PTH) and amino acid levels in human subjects were measured. Intracellular calcium and cyclic adenosine monophosphate (cAMP) levels in rat adipocytes were measured by laser scanning confocal microscopy and ELISA, respectively. The results revealed that serum triglyceride (TG), total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), TNF-α, IL-6 and PTH levels were significantly higher in the obese individuals versus the controls. By contrast, serum vitamin D and amino acid concentrations were lower in the obese individuals versus the controls. In addition, intracellular calcium levels were higher, while cAMP levels were lower in the obese rat adipocytes compared with the control group. However, the gene and protein expression of CaSR in white adipose tissue did not differ between the obese groups and the controls. Thus, these results suggest that CaSR functions not through its expression, but rather through allosteric regulation in obese individuals.

Higher Serum Methionine Levels as a Predictive Factor in Patients With Irreversible Fulminant Hepatic Failure

AimFulminant hepatic failure (FHF) which is characterized by acute massive liver necrosis in the absence of chronic liver disease, shows an imbalance of amino acid levels resulting from acute hepatocyte necrosis. We investigated plasma free amino acid profiles among FHF patients. MethodsThis retrospective review of 25 patients investigated laboratory profiles including changes in plasma amino acid concentrations before conventional treatment. ResultsThe causes of FHF were acute hepatitis B (n = 11) or unknown (n = 14). Six patients recovered after conventional treatment. Among the remaining 19, 7 underwent living donor liver transplantation (LDLT), and 12 were not eligible for a graft and successful due to combined multiple organ failure. The pretreatment amino acid plasma profiles were typical for hepatic failure, with abnormally high levels of phenylalanine and tyrosine as well as decreased valine, leucine, and isoleucine. In addition, the levels of many other amino acids, such as alanine, lysine, glutamine, methionine, or arginine, were increased. Among the increased serum amino acids levels, we observed a significant increase in serum methionine levels among FHF patients who died or underwent LDLT, compared with FHF cases who survived after conventional treatments. ConclusionThe markedly increased serum levels of methionine may be associated with the severity of liver damage, which could lead to impaired liver regeneration and multiple organ failure among FHF patients.

Metabolomics‐guided amino acid analysis reveals acetaminophen overdose‐induced disruption of arginine metabolism in mouse

Acetaminophen (APAP) overdose is a major cause of acute liver failure. Significant changes in lipids, glucose, and thiol antioxidants have been observed in APAP‐induced hepatotoxicity (AIH). However, the influences of AIH on amino acid metabolism are not well characterized. In this study, the profiles of free serum amino acids in the wild‐type (WT) and Cyp2e1‐null (KO) mice after APAP (400 mg/kg BW) treatment were defined through metabolomics‐guided biochemical analysis. Consistent to different sensitivity to AIH, serum amino acid levels differed greatly between WT and KO mice. Among observed changes in amino acids, APAP‐induced change in arginine was the most dramatic. After APAP treatment, serum arginine in WT mice became undetectable within 2 hours, while its level in KO mice was reduced at early time points but recovered quickly. This depletion of serum arginine in WT mice was well correlated to the increased arginase activity in serum, suggesting the release of arginase from the liver is the main cause of arginine depletion. Accompanying with rapid degradation of serum arginine, the distribution of arginine in WT mice as well as the levels of arginine metabolites was also dramatically affected. All these observations warrant further investigation on the role of arginine in AIH.

Two cases of refractory polymyositis accompanied with steroid myopathy

Polymyositis (PM) is an inflammatory muscle disease characterized by chronic inflammation in skeletal muscle. Although most patients with PM respond to corticosteroids, some cases show an unsatisfactory response and other therapeutic options must be considered. Furthermore, glucocorticosteroid (GC) toxicity leads to a significant disability known as steroid myopathy, particularly in elderly patients. Here we report two patients with refractory PM. Combined treatment with high-dose GCs, tacrolimus, and intravenous immunoglobulin resulted in beneficial effects against myositis. However, muscle weakness and the disability progressed due to steroid myopathy, and subsequent oral intake became impossible because of swallowing disturbance in these two patients. Nutritional intervention, including branched-chain amino acids (BCAAs) and rehabilitation, was undertaken in addition to treatment against myositis. These treatments finally improved the muscle weakness and activities of daily living, and the two patients were discharged after recovery. The high-dose GC treatment caused elevation of serum levels of amino acids, including BCAAs, but these amino acids subsequently declined during BCAA replacement therapy. These findings suggest that the catabolic effects of the glucocorticoid treatment impair the balance of amino acids, including BCAAs, within the muscle, leading to steroid myopathy.

The Effect of the Serum Amino Acid Levels Thiosemicarbazone Derivatives and its Metal Complexes on Rats

Advers biological activities of Thiosemicarbazone (TSC) and Schiff base (SB) derivatives have been widely studied in rats and in other animal species using different doses, times and routes of administration. To date, no attempt has been made to study alterations occurring in the amino acid profile in the effects of the thiosemicarbazone derivative and its metal complexes on the rats. At this study, the rats were injected subcutaneously with a new thiosemicarbazone and its LH-Zn and LH-Cu complexes (25 mg/kg body weight) and then sacrified after 15th days. The aim of this study was to determine the effect of new compounds on the serum amino acid levels in rats. In the comparision done among groups, it was observed that serum amino acid concentrations were statistically changed (p < 0.05).

Hyperammonemic coma in a post-partum patient with undiagnosed urea cycle defect

Urea cycle disorders (UCD) are common during neonatal period, and it is rarely reported in adults. We are reporting a patient presenting with post-partum neuropsychiatric symptoms rapidly progressing to coma. Markedly raised serum ammonia level on presentation with an initial normal magnetic resonance imaging (MRI) of brain and normal liver function tests led to the suspicion of UCD, which was confirmed on the basis of urine orotic acid and elevated serum amino acid levels. We had to resort to hemodialysis to correct the hyperammonemic coma, which was unresponsive to conventional anti-ammonia measures. She exhibited remarkable improvement with a progressive decline in serum ammonia with repeated hemodialysis and made a full recovery. Timely diagnosis and early institution of hemodialysis in the setting of a poor neurological status maybe considered a suitable treatment option.

24th Symposyum Croatian Society of Medical Biochemistry and Laboratory Medicine, Laboratory medicine in sports

Introduction:Intensive exercising may significantly damage muscles which is reflected in pain, fatigue and the increase of muscle proteins concentrations in blood such are creatinin kinase (CK), lactic dehydrogenase (LD), myoglobin (MB) and other biochemical parameters including urea serum concentration (SU). Biochemical markers vary with age, sex, race, muscle mass, physical activity and climate conditions. They also assist us in determining the limit between the capacity for adaptation to given training process which results in supercomepensation and in condition of overtraining (OT), in the case of load that exceeds the physiologic potential of regeneration. Concerning the problem of diagnosis and explanation of the symptoms of overtraining, markers that can apply reliably and with sufficient sensitivity and simplicity of interpretation in the praxis are sought. It is critical to take into account difference among individuals and groups that could hamper the interpretation.The most frequently used markers:The most frequently used biomarkers that provide us with the information on physical activity and on the amount of load through exercise are CK, SU and LD. Level of serum retaining kinas has been measured and interpreted for years as part of different scientific and professional investigations and presents one of basic parameters for determining the level of muscle damage. It reaches maximal concentration of the fourth day of exercising which depends on the type of exercise and the nature of stress triggered by exercise but also on individual characteristics.The level of serum urea presents marker of nitric compounds metabolism and is the principle chemical substance in the urine of mammals. It is thus possible to draw a parallel between the increases of serum urea concentration on increased degradations of proteins. Significant fall of serum amino acid levels occurs after sixty to seventy minutes of exercising with the increase of urea and free tyrosine and these changes have high correlation with the duration and intensity of.LD changes are important index of well-trained sportsmen and their capability to withstand the pace and force during strain in the training process. The level of LD is a good index of exercise intensity and marker of metabolic exchange in tissues whose concentration in serum is dependent of cell damage.Conclusion:There is not a single, unique parameter that would provide enough valuable information for the estimation of the quality of exercising, amount of load and identification of overtraining. Delayed measurement of biomarkers is far from ideal, but it is obvious that the amount of stress/ load in training is the most important factor for the development of state of overtraining. Daily body weight control, diet, biochemical indices values and the input of water should be known and standardized before measurements. For the most of parameters determination of basal levels are needed in specific populations for more accurate interpretation and evaluation of results. The sampling process itself should be under the most strict conditions of standardization by repeating measurement at least every third day. Dependence of mentioned parameters (SU, CK, LD) on exercise intensity varies among individuals and without these additional measurements and subpopulation evaluations it is difficult to come to conclusions with certainty as well as to come to conclusions on causative correlations of training load and dynamic in biochemical parameters.

CLINICAL STUDY OF THE EFFECTS OF LOW-PROTEIN DIET AND SUPPLEMENTED WITH α-KETOACIDS THERAPY ON NUTRITION STATUS AND RESIDUAL RENAL FUNCTION IN CONTINUOUS AMBULATORY PERITONEAL DIALYSIS(CAPD) PATIENTS

It is critical to preserve residual renal function (RRF) in CAPD, as RRF is associated with lower morbidity and mortality. low- protein diet supplemented with α-keto acids was reported to have an important roles in delaying in follow-up period progression of renal failure and relieving malnutritional status in non-dialysis patients with chronic renal failure. We evaluate the effects on the nutritional status and RRF of a low-protein diet supplemented with α-keto acids on CAPD patients prospectively. Seventy eight CAPD patients who were randomly assigned to a low-protein diet supplemented with α-keto acid group(keto acid group,31 patients),low-protein diet group(LPD group,26 patients)and routine protein diet group(RPD group,21 patients)were investigated and followed up for one year. The nutritional parameters were measured, and examinations of residual renal function (RRF), Kt/v, clearance of creatinine (Ccr) and levels of serum amino acids, mean arterial pressure (MAP), peritoneal ultrafiltration(UF),residual urine volume(RUV) and the status of water-sodium retentio were performed. Compared to LPD group, serum levels of prealbumin(PA), transferrin (TRF) retinal binding protein (RBP) had a significant increment both in keto acid group and RPD group(P〈0.01),but there was no significance between these two groups(p〉0.05)□Compared to RPD group, There was an incremental tendency in albumin(Alb), total cholesterol(TC), triglyceride (TG), Triceps skinfoles (TSF),midarm riuscle circumference(MAMC),body mass index(BMI) in keto acid group, but no significance(p〉0.05)□The serum concentrations of Valine(Val),Leucine(Leu), Isoleucine (Ile) were significantly increased in keto acid group(p〈0.01),compared to the other groups. Levels of RRF, Kt/V, Ccr, RUV were significantly higher both in keto acid group and LPD group than in RPD group(p〈0.01)□There were no significant differences in MAP, UF and peritoneal dialysate albumin loss between these groups, However, the trend of peritoneal dialysate albumin loss in keto acid group and LPD group was descendent□ Proteinuria decreased most significantly in keto acid group (P〈0.01).In conclusion, Low-protein diet supplemented with α-keto acids therapy has a tendency of protecting RRF in CAPD patients while relieving malnutritional status and improving the 1evels of branched chain amino acids.

Serum Amino Acid Levels as a Biomarker for Renal Cell Carcinoma

Prognosis in renal cell carcinoma is dependent on tumor stage at presentation, with significant differences in survival between early and late stage disease. Currently to our knowledge no screening tests or biomarkers have been identified for the early detection of kidney cancer. Therefore, we investigated whether serum amino acid profiles are a potentially useful biomarker in patients with renal cell carcinoma. The concentrations of 26 amino acids were determined in serum taken preoperatively from 189 patients with renal cell carcinoma, and from 104 age and sex matched controls. Statistically significant changes were observed in patient levels of 15 amino acids, with 13 being decreased and 2 being increased. A logistic regression model using 8 amino acids including cysteine, ornithine, histidine, leucine, tyrosine, proline, valine and lysine was created to distinguish cases from controls. A receiver operator curve based on this model had an area under the curve of 0.81. This same model also had predictive value in terms of overall survival and tumor recurrence in patients with renal cell carcinoma. Our findings suggest that serum amino acid levels may be useful as a screening tool for the identification of individuals with renal cell carcinoma and the prediction of outcomes.

Oral Administration of an Enzymatic Protein Hydrolysate from the Green MicroalgaChlorella vulgarisEnhances the Nutritional Recovery of Malnourished Mice

This study examined the effects of oral administration of an enzymatic protein hydrolysate from green microalga Chlorella vulgaris (Cv-PH) on the nutritional recovery of malnourished Balb/c mice after a 3-day fasting period. Mice were refed with commercial diet supplemented or not supplemented with Cv-PH (500 mg/kg) for 8 days. Regardless of the diet used during refeeding, animal body weights and serum protein concentrations did not differ between groups. Mice given Cv-PH had a significant increase in hemoglobin concentrations. Most serum amino acid levels were similar in the control and Cv-PH animals. Starved mice refed with Cv-PH showed normal liver functions, as judged by liver weight, protein concentration, and the enzymatic activities of cholinesterase and arginase. Cv-PH increased DNA, protein content, and gut-mucosal weight. In addition, brush-border oligosaccharidase activities were also higher in the Cv-PH group. These findings suggest that Chlorella protein hydrolysate can be used to develop specific formulations suitable for pharmacologic nutrition.

Glutamine, ornithine, citrulline and arginine levels in children with phenylketonuria: The diet effect

Background Phenylketonuria (PKU) therapeutic diet is characterized by the great replacement of natural protein with a phenylalanine-free formula. Aim To investigate the effect of diet on the amino acid serum levels in PKU patients and their total antioxidant status (TAS). Methods Thirty-seven poorly controlled patients (group A), 43 patients who strictly adhered to their diet (group B) and 50 controls were included in the study. In patients and controls blood chemistry, TAS and serum amino acid level determinations were performed. Results Phenylalanine levels significantly differed among the groups. Glutamine and ornithine levels were significantly higher in group A, while TAS (416 ± 30 vs 228 ± 23 μmol/L, p < 0.001), citrulline (39 ± 15 vs 26 ± 5 μmol/L, p < 0.001) and arginine levels (61 ± 11 vs 80 ± 12 μmol/L, p < 0.001) were higher in group B. The other determined amino acid serum levels did not differ among the groups of patients and controls. Conclusions The high glutamine and ornithine levels in group A may reflect the high natural protein intake. High phenylalanine levels in these patients may locally affect the hepatocyte, enterocyte, and/or renal function resulting in low citrulline and arginine levels contributing to their low TAS.

Increased serum levels of L-arginine in ulcerative colitis and correlation with disease severity

L-arginine (L-Arg) is a semi-essential amino acid that is the substrate for both nitric oxide and polyamine synthesis. Cellular uptake of L-Arg is an active transport process that is subject to competitive inhibition by L-ornithine (L-Orn) and L-lysine (L-Lys). We investigated L-Arg utilization in patients with ulcerative colitis (UC). Serum was collected from 14 normal controls and 22 UC patients with pancolitis of moderate or severe activity by histopathology score. The Mayo Disease Activity Index (DAI) and endoscopy subscore were assessed. Serum amino acid levels were measured by high-performance liquid chromatography. Arginine availability index (AAI) was defined as [L-Arg]/([L-Orn] + [L-Lys]). Serum L-Arg levels were significantly associated with histopathologic grade (P = 0.001). L-Arg levels were increased in subjects with severe colitis when compared to those with moderate colitis or normal mucosa. L-Orn + L-Lys levels were also increased in severe colitis, so that AAI was not significantly increased. L-Arg levels were also strongly associated with the endoscopy subscore (P < 0.001). There was a strong correlation between DAI and L-Arg levels (r = 0.656, P < 0.001). Serum L-Arg levels correlate with UC disease severity but availability is not increased due to competitive inhibition by L-Orn and L-Lys. Our findings suggest that L-Arg uptake by cells in the inflamed colon is defective, which may contribute to the pathogenesis of UC. Studies delineating the mechanism of uptake inhibition could enhance our understanding of UC or lead to novel treatment options.

The etiology and prevention of feeding intolerance paralytic ileus--revisiting an old concept.

Gastro-intestinal (G-I) motility is impaired ("paralytic ileus") after abdominal surgery. Premature feeding attempts delay recovery by inducing "feeding intolerance," especially abdominal distention that compromises respiration. Controlled studies (e.g., from Sloan-Kettering Memorial Hospital) have lead to recommendations that patients not be fed soon after major abdominal surgery to avoid this complication.We postulate that when total fluid inflow of feedings, digestive secretions, and swallowed air outstrip peristaltic outflow from the feeding site, fluid accumulates. This localized stagnation triggers G-I vagal reflexes that further slow the already sluggish gut, leading to generalized abdominal distention. Similarly, vagal cardiovascular reflexes in susceptible subjects could account for the 1:1,000 incidence of unexplained bowel necrosis reported with enteral feeding.We re-evaluated our data, which supports this postulated mechanism for the induction of "feeding intolerance." We had focused our efforts on postoperative enteral nutrition, with the largest reported series of immediate feeding of at least 100 kcal/hour after major surgery. We found that this complication can be avoided consistently by monitoring inflow versus peristaltic outflow, immediately removing any potential excess from the feeding site.We fed intraduodenally immediately following "open" surgery for 31 colectomy and 160 consecutive cholecystectomy patients. The duodenum was aspirated simultaneously just proximal to the feeding site, efficiently removing all swallowed air and excess feedings. To salvage digestive secretions, the degassed aspirate was re-introduced manually (and later automatically) via a separate feeding channel.Hourly assays were performed for nitrogen balance, serum amino acids, and for the presence of removed feedings in the aspirate. The colectomy patients had X-ray motility studies initiated 5 – 17 hours after surgery.Clinically normal motility and absorption resumed within two hours. Fed BaSO4 traversed secure anastomoses, to exit in bowel movements within 24–48 hours of colectomy. All patients were in positive protein balance within 2 – 24 hours, with elevated serum amino acids levels and without adverse G-I effects.Limiting inflow to match peristaltic outflow from the feeding site consistently prevented "feeding intolerance." These patients received immediate full enteral nutrition, with the most rapid resolution of postoperative paralytic ileus, to date.