Pectin modulates intestinal immunity in a pig model via regulating the gut microbiota-derived tryptophan metabolite-AhR-IL22 pathway

Background Pectin is a heteropolysaccharide that acts as an intestinal immunomodulator,promoting intestinal development and regulating intestinal flora in the gut.However,the relevant mechanisms remain obscure.In this study,pigs were fed a corn-soybean meal-based diet supplemented with either 5%microcrystalline cellulose(MCC)or 5%pectin for 3 weeks,to investigate the metabolites and anti-inflammatory properties of the jejunum.Result The results showed that dietary pectin supplementation improved intestinal integrity(Claudin-1,Occludin)and inflammatory response[interleukin(IL)-10],and the expression of proinflammatory cytokines(IL-1β,IL-6,IL-8,TNF-α)was down-regulated in the jejunum.Moreover,pectin supplementation altered the jejunal microbiome and tryptophan-related metabolites in piglets.Pectin specifically increased the abundance of Lactococcus,Enterococcus,and the microbiota-derived metabolites(skatole(ST),3-indoleacetic acid(IAA),3-indolepropionic acid(IPA),5-hydroxyindole-3-acetic acid(HIAA),and tryptamine(Tpm)),which activated the aryl hydrocarbon receptor(AhR)pathway.AhR activation modulates IL-22 and its downstream pathways.Correlation analysis revealed the potential relationship between metabolites and intestinal morphology,intestinal gene expression,and cytokine levels.Conclusion In conclusion,these results indicated that pectin inhibits the inflammatory response by enhancing the AhR-IL22-signal transducer and activator of transcription 3 signaling pathway,which is activated through tryptophan metabolites.

Ochratoxin A induces abnormal tryptophan metabolism in the intestine and liver to activate AMPK signaling pathway

Background Ochratoxin A(OTA)is a mycotoxin widely present in raw food and feed materials and is mainly pro-duced by Aspergillus ochraceus and Penicillium verrucosum.Our previous study showed that OTA principally induces liver inflammation by causing intestinal flora disorder,especially Bacteroides plebeius(B.plebeius)overgrowth.However,whether OTA or B.plebeius alteration leads to abnormal tryptophan-related metabolism in the intestine and liver is largely unknown.This study aimed to elucidate the metabolic changes in the intestine and liver induced by OTA and the tryptophan-related metabolic pathway in the liver.Materials and methods A total of 30 healthy 1-day-old male Cherry Valley ducks were randomly divided into 2 groups.The control group was given 0.1 mol/L NaHCO3 solution,and the OTA group was given 235μg/kg body weight OTA for 14 consecutive days.Tryptophan metabolites were determined by intestinal chyme metabolomics and liver tryptophan-targeted metabolomics.AMPK-related signaling pathway factors were analyzed by Western blot-ting and mRNA expression.Results Metabolomic analysis of the intestinal chyme showed that OTA treatment resulted in a decrease in intesti-nal nicotinuric acid levels,the downstream product of tryptophan metabolism,which were significantly negatively correlated with B.plebeius abundance.In contrast,OTA induced a significant increase in indole-3-acetamide levels,which were positively correlated with B.plebeius abundance.Simultaneously,OTA decreased the levels of ATP,NAD+and dipeptidase in the liver.Liver tryptophan metabolomics analysis showed that OTA inhibited the kynurenine metabolic pathway and reduced the levels of kynurenine,anthranilic acid and nicotinic acid.Moreover,OTA increased the phosphorylation of AMPK protein and decreased the phosphorylation of mTOR protein.Conclusion OTA decreased the level of nicotinuric acid in the intestinal tract,which was negatively correlated with B.plebeius abundance.The abnormal metabolism of tryptophan led to a deficiency of NAD+and ATP in the liver,which in turn activated the AMPK signaling pathway.Our results provide new insights into the toxic mechanism of OTA,and tryptophan metabolism might be a target for prevention and treatment.

T cells in pancreatic cancer stroma:Tryptophan metabolism plays an important role in immunoregulation

Several studies have shown that the immune system is highly regulated by tryptophan metabolism,which serves as an immunomodulatory factor.The indoleamine 2,3-dioxygenase 1(IDO1),as an intracellular enzyme that participates in metabolism of the essential amino acid tryptophan in the kynurenine pathway,is an independent prognostic marker for pancreatic cancer(PC).First,overexpression of IDO1 inhibits the maturation of dendritic cells and T-cell proliferation in the liver and spleen.Second,the high expression of kynurenine induces and activates the aryl hydrocarbon receptor,resulting in upregulated programmed cell death protein 1 expression.Third,the induction of IDO1 can lead to loss of the T helper 17 cell/regulatory T cell balance,mediated by the proximal tryptophan catabolite from IDO metabolism.In our study,we found that overexpression of IDO1 upregulated CD8+T cells and reduced natural killer T cells in pancreatic carcinoma in mice.Hence,it may be essential to pay more attention to tryptophan metabolism in patients,especially those who are tolerant to immunotherapy for PC.

Tryptophan Metabolism and Gut Microbiota

Background: Tryptophan metabolites such as serotonin, kynurenine, or kynurenic acids are considered to be the most important metabolites of gut microbiota. We wanted to know about changes in tryptophan metabolites in various diseases in which the etiology gut microbiota are considered to participate. Methods: Ultra-high speed liquid chromatography/mass spectroscopy (LC/MS) has been used to analyze simultaneously all the tryptophan metabolites, which we have explored for the first time in the world. Results: We analyzed plasma levels of tryptophan metabolites in patients with depression, autism, diabetes mellitus ‘DM’), and acute coronary syndrome (ACS). Of all the metabolites serotonin and kynurenine levels of these patients were higher than those of controls. Conclusion: Measurements of tryptophan metabolites in plasma of various diseases are important to know roles of gut microbiota in etiology, further therapeutic measures.

Kynurenine pathway of tryptophan metabolism in pathophysiology and therapy of major depressive disorder

Serotonin deficiency in major depressive disorder(MDD)has formed the basis of antidepressant drug development and was originally attributed to induction of the major tryptophan(Trp)-degrading enzyme,liver Trp 2,3-dioxygenase(TDO),by cortisol,leading to decreased Trp availability to the brain for serotonin synthesis.Subsequently,the serotonin deficiency was proposed to involve induction of the extrahepatic Trp-degrading enzyme indoleamine 2,3-dioxygenase(IDO)by proinflammatory cytokines,with inflammation being the underlying cause.Recent evidence,however,challenges this latter concept,as not all MDD patients are immune-activated and,when present,inflammation is mild and/or transient.A wide range of antidepressant drugs inhibit the activity of liver TDO and bind specifically to the enzyme,but not to IDO.IDO induction is not a major event in MDD,but,when it occurs,its metabolic consequences may be masked and overridden by upregulation of kynurenine monooxygenase(KMO),the gateway to production of modulators of immune and neuronal functions.KMO appears to be activated in MDD by certain proinflammatory cytokines and antidepressants with anti-inflammatory properties may block this activation.We demonstrate the ability of the antidepressant ketamine to dock(bind)to KMO.The pathophysiology of MDD may be underpinned by both the serotonin deficiency and glutamatergic activation mediated respectively by TDO induction and N-methyl-D-aspartate receptor activation.Inhibition of TDO and KMO should be the focus of MDD pharmacotherapy.

The Dependence of <i>N</i>-Malonyltryptophan Formation in Plants on Water Deficit (Review)

Drought stress in plants is accompanied by several metabolic changes. One of them is the appearance of N-malonyltryptophan (MT) during leaf wilting of many species, but there is a significant number of plant species in which the appearance of MT did not occur. Plants of some species were able to synthesize also N-acetyltryptophan (AT). Excised tomato leaves incubated with D-amino acids (including D-Trp) transform them into malonyl- and acetyl-derivatives even without water deficit. However, MT which appeared during water deficit has been shown to contain L-Trp. Amino acid—1-amino-cyclopropane-1-carboxylic acid (ACC) is also malonylated during water deficit, but other L-amino acids were not malonylated. N-malonyl transferases specific for Trp and ACC have been found in several plants. The existence of N-malonyltransferase specific to L-Trp and appeared during water deficit in plants forming MT is supposed, but clear experimental proof has not been obtained yet. Plants can transform MT applied exogenously into Trp and further to indole-3-acetic acid (IAA). But no evidence has been appeared up to now that endogenous MT may be a source of IAA. It is unknown till now why it is necessary for plants of many species to malonylate only Trp during water deficit. How MT metabolized in animals and if it affects them is also unknown. The necessity to use molecular-genetic approaches for the elucidation of the physiological significance of MT formation during water deficit is underlined.

Helicobacter pylori and serum kynurenine-tryptophan ratio in patients with colorectal cancer

AIM: To evaluate how Helicobacter pylori(H. pylori) is able to evade the immune response and whether it enhances systemic immune tolerance against colorectal cancer.METHODS: This prospective randomized study involved 97 consecutive colorectal cancer patients and 108 cancer-free patients with extra-digestive diseases. Colorectal cancer and cancer-free patients were assigned into subgroups according to H. pylori Ig G seropositivity. Exposure to H. pylori was determined by Ig G seropositivity which was detected by enzyme linked immunoassay(ELISA). Serum neopterin levels were measured by ELISA. Serum tryptophan, kynurenine, and urinary biopterin concentrations were measured by high performance liquid chromatography. Serum nitrite levels were detected spectrophotometrically. Serum indoleamine 2,3-dioxygenase activity was estimated by the kynurenine to tryptophan ratio and by assessing the correlation between serum neopterin concentrations and the kynurenine to tryptophan ratio. The frequencies of increased serum kynurenine to tryptophan ratio of H. pylori seronegative and seropositive colorectal cancer subgroups were estimated by comparing them with the average kynurenine to tryptophan ratio of H. pylori seronegative tumor-free patients.RESULTS: Compared with respective controls, in both H. pylori seronegative and seropositive colorectal cancer patients, while serum tryptophan levels were decreased(controls vs patients; seronegative: 20.37 ± 0.89 μmol/L vs 15.71 ± 1.16 μmol/L, P < 0.05; seropositive: 20.71 ± 0.81 μmol/L vs 14.97 ± 0.79 μmol/L, P < 0.01) the kynurenine to tryptophan ratio was significantly increased(controls vs patients; seronegative: 52.85± 11.85 μmol/mmol vs 78.91 ± 8.68 μmol/mmol, P < 0.01, seropositive: 47.31 ± 5.93 μmol/mmol vs 109.65 ± 11.50 μmol/mmol, P < 0.01). Neopterin concentrations in cancer patients were significantly elevated compared with controls(P < 0.05). There was a significant correlation between serum neopterin levels and kynurenine/tryptophan in control and colorectal cancer patients groups(r s = 0.494, P = 0.0001 and r s= 0.293, P = 0.004, respectively). Serum nitrite levels of H. pylori seropositive cancer cases were significantly decreased compared with seropositive controls(controls vs patients; 26.04 ± 2.39 μmol/L vs 20.41 ± 1.48 μmol/L, P < 0.05) The decrease in the nitrite levels of H. pylori seropositive cancer patients may be attributed to excessive formation of peroxynitrite and other reactive nitrogen species.CONCLUSION: A significantly high kynurenine/tryptophan suggested that H. pylori may support the immune tolerance leading to cancer development, even without an apparent upper gastrointestinal tract disease.

Generation of tryptophan hydroxylase 2 gene knockout pigs by CRISPR/Cas9-mediated gene targeting

Unbalanced brain serotonin(5-HT) levels have implications in various behavioral abnormalities and neuropsychiatric disorders. The biosynthesis of neuronal 5-HT is regulated by the rate-limiting enzyme, tryptophan hydroxylase-2(TPH2). In the present study, the clustered regularly interspaced short palindromic repeat(CRISPR)/CRISPR-associated(Cas) system was used to target the Tph2 gene in Bama mini pig fetal fibroblasts. It was found that CRISPR/Cas9 targeting efficiency could be as high as 61.5%, and the biallelic mutation efficiency reached at38.5%. The biallelic modified colonies were used as donors for somatic cell nuclear transfer(SCNT) and 10 Tph2 targeted piglets were successfully generated. These Tph2 KO piglets were viable and appeared normal at the birth.However, their central 5-HT levels were dramatically reduced, and their survival and growth rates were impaired before weaning. These Tph2 KO pigs are valuable large-animal models for studies of 5-HT deficiency induced behavior abnomality.

Lysine, Methionine and Tryptophan Requirements of Beijing Ducklings of 0-2 Weeks of Age

A feed trial was conducted with a total of 1 134 Beijing ducklings to study the optimum level of dietary lysine (Lys) (0.95,1.10, 1.25%), methionine (Met) (0.26, 0.46, 0.66%) and tryptophan (Trp) (0.20, 0.30, 0.40%) for those ducklings during aphase of 0-2 weeks. Ducklings were randomly allotted to 27 groups according to a 3 × 3 × 3 factorial arrangement and feda basal corn-soybean-peanut meal diet containing 20.26% CP, 12.45 MJ kg-1 ME. The results from this study indicate thatLys affected body weight (P < 0.01), feed intake (0-14 d) (P < 0.01), but had no effect on feed/gain (0-14 d) (P > 0.05), uric acidconcentration (P > 0.05). Methionine influenced body weight (P < 0.01), feed/gain (P < 0.05), and feed intake (P < 0.01).Tryphtophan had no effect on indices measured. The requirement of the Lys and Met for Beijing ducklings of 0-2 weeksof age were 1.10 and 0.46%. The requirement of Trp for Beijing ducklings of 0-2 weeks of age was not more than 0.20%.

Compared efficacy of University of Wisconsin and histidine-tryptophan-ketoglutarate solutions in ex-situ liver resection and autotransplantation for end-stage hepatic alveolar echinococcosis patients

Background: The University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) solutions are the two most frequently used liver graft preservation fluids. The present study aimed to compare their efficacy in end-stage hepatic alveolar echinococcosis patients who underwent ex-situ liver resection and autotransplantation (ELRA). Methods: A total of 81 patients received ELRA from August 2010 to March 2018. They were allocated into UW ( n = 48) and HTK groups ( n = 33) based on the type of solutions used. Demographic and operational data were retrospectively analyzed. Primary outcomes included 90-day mortality, incidence of early graft loss, primary dysfunction, and postoperative complications. Results: Demographic and operational characteristics were similarly distributed in the two groups. No statistically significant differences were observed with regard to 90-day mortality (12.77% vs. 12.12%) and early graft loss rate (8.51% vs. 9.09%) between the two groups. Patients in the UW and HTK groups showed a primary dysfunction rate of 27.66% and 27.27%, respectively. The UW group exhibited a higher incidence tendency of biliary complications, albeit with no statistical significance. Conclusions: This is the largest cohort study comparing the efficacy of the UW and HTK organ-preserving solutions in end-stage hepatic alveolar echinococcosis patients in ELRA settings. UW and HTK solutions presented similar efficacy and safety. A randomized clinical trial with larger scale is needed for further investigation in future clinical applications.

Measurement of Tryptophan Metabolites in Healthy Old Men and Patients of Type 2 Diabetes Mellitus (T2DM)

Background: Plasma levels of tryptophan (TRP) metabolites have not been measured extensively in patients of type 2 diabetes mellitus (T2DM). Methods: Metabolites analysis was performed by a liquid chromatograph tandem mass spectrometer, the LCMS-8060 quadrupole mass spectrometer combined with Nexera X2 liquid chromatograph system (Shimadzu Corporation, Kyoto, Japan). Body mass index (BMI) and TRP metabolites have been measured in healthy old men (n = 20) and patients of T2DM (n = 20). TRP metabolites were measured by using the ultrahigh speed liquid chromatography-mass spectros-copy (Shimadzu Corporation). Results: The plasma levels of 5-hydroxytryptophan (5-HTRP), 5-hydroxyindoleacetic acid (5-HIAA), kynurenic acid (KNA), 3-hydroxykynurenine (3-HKN), and 3-hydroxyanthranilic acid (3-HAA) were higher in patients of T2DM than healthy old men. Since 5HTRP and 5-HIAA belong to the serotonin pathway, and KNA, 3-HKN, and 3-HAA belong to the KN pathway of TRP metabolism, these pathways were activated more in the patients of T2DM. Since plasma levels of Indole-3-acetic acid were not elevated in T2DM, that pathway was not activated more in T2DM. Serotonin levels were not increased but 5-HIAA levels were increased in the plasma of T2DM patients, which may mean that serotonin was quickly metabolized to 5-HIAA in the patients of T2DM. Conclusion: Plasma levels of tryptophan metabolites in serotonin and kynurenine pathways increased in T2DM patients. Obesity expressed by BMI may not influence tryptophan metabolism in healthy old men and T2DM patients. These results indicate that our new method of the simultaneous measurements of all the tryptophan metabolites is the powerful measure to identify factor related to endogenous stresses seen in DM.

Separation of tryptophan enantiomers with molecularly imprinted polypyrrole electrode column

In this study,we have fabricated molecularly imprinted polypyrrole(PPy) packed electrode columns and investigated their effects on separation of tryptophan(Trp) enantiomers by using potential control.The results indicate that the imprinted PPy electrode columns could efficiently enhance the L-Trp uptake and separate Trp enantiomers effectively,implying the great potential for the enantioselective recognition of other amino acids enantiomers.

Gut Microbiota-Controlled Tryptophan Metabolism Improves D-Gal/LPS-Induced Acute Liver Failure in C57BL/6 Mice

Acute liver failure(ALF)has an abrupt onset with a frequently fatal outcome.Previous studies have found that oral antibiotics prevent drug-induced liver injury in animal experiments,indicating that the gut microbiota plays a critical role in the pathophysiological process.However,the underlying mechanism has not been fully understood.This study explored the comprehensive role of the gut microbiota in ALF using multi-omics.A cocktail of broad-spectrum antibiotics(Abx)pretreatment by gavage for four weeks improved the survival of D-(+)-galactosamine hydrochloride(D-Gal)/lipopolysaccharide(LPS)-induced ALF in C57BL/6 mice.RNA sequencing showed that inflammatory responses were inhibited and metabolic pathways were upregulated in the liver of Abx-treated ALF mice.The 16S rRNA gene sequencing revealed that Abx reshaped the composition and function of the gut microbiota,with an increased proportion of tryptophan(Trp)metabolism.In addition,global metabolic profiling by ultraperformance liquid chromatography–mass spectrometry(UPLC–MS)indicated that the gut microbiota post-Abx intervention reduced Trp excretion,liberated more Trp to the host,and enhanced the kynurenine(Kyn)pathway with increased production of Kyn.As an endogenous aryl hydrocarbon receptor(AhR)ligand,Kyn has anti-inflammatory and immunosuppressive effects.Furthermore,AhR-targeted treatments affected the outcome of ALF mice with or without Abx pretreatment,indicating that AhR directly regulated susceptibility to ALF,at least in part.This study demonstrates that the gut microbiota-dependent control of the Trp metabolism could regulate host susceptibility to ALF by modulating the activity of AhR,and thus provides a promising target for better management of ALF.

Alteration of fecal tryptophan metabolism correlates with shifted microbiota and may be involved in pathogenesis of colorectal cancer

BACKGROUND Gut tryptophan(Trp)metabolites are produced by microbiota and/or host metabolism.Some of them have been proven to promote or inhibit colorectal cancer(CRC)in vitro and animal models.We hypothesized that there is an alteration of gut Trp metabolism mediated by microbiota and that it might be involved in the pathogenesis of cancer in patients with CRC.AIM To investigate the features of Trp metabolism in CRC and the correlation between fecal Trp metabolites and gut microbiota.METHODS Seventy-nine patients with colorectal neoplastic lesions(33 with colon adenoma and 46 with sporadic CRC)and 38 healthy controls(HCs)meeting the inclusion and exclusion criteria were included in the study.Their demographic and clinical features were collected.Fecal Trp,kynurenine(KYN),and indoles(metabolites of Trp metabolized by gut microbiota)were examined by ultraperformance liquid chromatography coupled to tandem mass spectrometry.Gut barrier marker and indoleamine 2,3-dioxygenase 1(IDO1)mRNA were analyzed by quantitative realtime polymerase chain reaction.Zonula occludens-1(ZO-1)protein expression was analyzed by immunohistochemistry.The gut microbiota was detected by 16S ribosomal RNA gene sequencing.Correlations between fecal metabolites and other parameters were examined in all patients.RESULTS The absolute concentration of KYN[1.51(0.70,3.46)nmol/g vs 0.81(0.64,1.57)nmol/g,P=0.036]and the ratio of KYN to Trp[7.39(4.12,11.72)×10^-3 vs 5.23(1.86,7.99)×10^-3,P=0.032]were increased in the feces of patients with CRC compared to HCs,while the indoles to Trp ratio was decreased[1.34(0.70,2.63)vs 2.46(1.25,4.10),P=0.029].The relative ZO-1 mRNA levels in patients with CRC(0.27±0.24)were significantly lower than those in HCs(1.00±0.31)(P<0.001),and the relative IDO1 mRNA levels in patients with CRC[1.65(0.47-2.46)]were increased(P=0.035).IDO1 mRNA levels were positively associated with the KYN/Trp ratio(r=0.327,P=0.003).ZO-1 mRNA and protein levels were positively correlated with the indoles/Trp ratio(P=0.035 and P=0.009,respectively).In addition,the genera Asaccharobacter(Actinobacteria)and Parabacteroides(Bacteroidetes),and members of the phylum Firmicutes(Clostridium XlVb,Fusicatenibacter,Anaerofilum,and Anaerostipes)decreased in CRC and exhibited a positive correlation with indoles in all subjects.CONCLUSION Alteration of fecal Trp metabolism mediated by microbiota is associated with intestinal barrier function and tissue Trp metabolism,and may be involved in the pathogenesis of CRC.

Studies on the plasma tryptophan and urinary 5-hydroxy-3-indoleacetic acid in expedition members residing in Antarctica

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Differences of Plasma Levels of Tryptophan, Serotonin, 5-Hydroxyindole Acetic Acid, and Kynurenine between Healthy People and Patients of Major Monopolar Depression at Various Age and Gender

Background: It is not well analyzed whether there are differences in plasma levels of tryptophan (TRP) metabolites between healthy control people (HC) and patients of major monopolar depression (MMD). Methods: Ultra high-speed liquid chromatography/mass spectrometry has been used for the simultaneous determination of plasma levels of tryptophan metabolites in depressive patients. Results: There are no significant differences between plasma levels of TRP between HC and MMD. Plasma levels of TRP of HC are higher in young men, young women, old men, and old women in this order. Serotonin (5-HT) levels are higher in MMD than HC. Plasma levels of 5-HIAA of HC are also higher than those of patients of MMD. Plasma levels of kynurenine (KYN) of healthy old men and old women are higher than those of young men and old women. Plasma levels of KYN are higher in old women and young men of MMD than those of HC. Conclusion: Plasma levels of 5-HT are higher in patients of MMD than those of HC, which may suggest that use of drugs inhibiting the 5-HT transportation may increase plasma levels of 5-HT in MMD.

Altered tryptophan hydroxylase 2 expression in enteric serotonergic nerves in Hirschsprung's-associated enterocolitis

AIM: To determine if expression of colonic tryptophan hydroxylase-2(TPH2), a surrogate marker of neuronal 5-hydroxytryptamine, is altered in Hirschsprung's-associated enterocolitis. METHODS: Entire resected colonic specimens were collected at the time of pull-through operation in children with Hirschsprung's disease(HSCR, n = 12). Five of these patients had a history of pre-operative Hirschsprung's-associated enterocolitis(HAEC). Controls were collected at colostomy closure in children with anorectal malformation(n = 10). The distribution of expression of TPH2 was evaluated using immunofluorescence and confocal microscopy. Protein expression of TPH2 was quantified using western blot analysis in the deep smooth muscle layers. RESULTS: TPH2 was co-expressed in nitrergic and cholinergic ganglia in the myenteric and submucosal plexuses in ganglionic colon in HSCR and healthy controls. Co-expression was also seen in submucosal interstitial cells of Cajal and PDGFRα+ cells. The density of TPH2 immuno-positive fibers decreased incrementally from ganglionic bowel to transition zonebowel to aganglionic bowel in the myenteric plexus. Expression of TPH2 was reduced in ganglionic bowel in those affected by pre-operative HAEC compared to those without HAEC and healthy controls. However, expression of TPH2 was similar or high compared to controls in the colons of children who had undergone diverting colostomy for medically refractory HAEC.CONCLUSION: Altered TPH2 expression in colonic serotonergic nerves of patients with HSCR complicated by HAEC may contribute to intestinal secretory and motor disturbances, including recurrent HAEC.

Comparison of inhibitory effect between DL-tryptophan and lactoferrin on Pseudomonas aeruginosa biofilm formation in wound dressing

Objective: To compare the inhibitory effect between DL-tryptophan and bovine lactoferrin on biofilm formed by isolated Pseudomonas aeruginosa strains. Methods: The study was carried out on 40 patients suffering from surgical site infection. Wound pus was collected using sterile swabs after isolation, and identified by common bacteriological methods. Isolated Pseudomonas aeruginosa strains were grown on biofilm enhancing materials, and then the inhibitory effects of different concentrations of DL-tryptophan and lactoferrin were tested using scanning electron microscopy and microtitre plate methods. Results: There was no significant difference in the inhibitory effect between DL-tryptophan and lactoferrin at 0.5 mg/mL. While in concentration of 1 mg/mL and 2 mg/mL, tryptophan showed more significant inhibitory effect than lactoferrin. Conclusions: Both DL-tryptophan and bovine lactoferrin have inhibitory effect on Pseudomonas aeruginosa biofilm formation in a dose dependent manner, and the inhibitory effect of DL-tryptophan is stronger.

Decrease in Lysine and Tryptophan Content in S2 Inbred Lines from a Quality Protein Maize (QPM) Variety in a Breeding Program

Several countries in Africa, Latin America along with China have incorporated QPM in their Agricultural development plan. A new quality protein maize variety (QPM) was developed by breeders and farmers using the participatory breeding approach in the DR-Congo. It is adapted to all the maize growing regions in the country. Inbred lines from this new variety were produced for further development of maize synthetic populations. The main objective of the present study is to determine the level of amino acid changes in early generations of inbred lines. The results of the study revealed a significant decrease of 33% and 38% of tryptophan in S1 and S2 inbred lines compared to the original parental MUDISHI 3 population, respectively. There was a decrease of 15% of lysine in S2 inbred lines compared to the parental MUDISHI 3. Actually, S2 inbred lines of MUDISHI 3 contain similar level of lysine compared to the genetically improved normal maize (Salongo 2) that is currently released. The development of composite lines is recommended over synthetic populations to maintain the high levels of lysine and tryptophan along with other desirable agronomic characteristics since they involve the intercrossing of open pollinated varieties.

Molecular Docking of Bacosides with Tryptophan Hydroxylase:A Model to Understand the Bacosides Mechanism

Tryptophan hydroxylase(TPH)catalyses L-tryptophan into 5-hydroxy-L-tryptophan,which is the first and ratelimiting step of serotonin(5-HT)biosynthesis.Earlier,we found that TPH2 up-regulated in the hippocampus of postnatal rats after the oral treatment of Bacopa monniera leaf extract containing the active compound bacosides.However,the knowledge about the interactions between bacosides with TPH is limited.In this study,we take advantage of in silico approach to understand the interaction of bacoside-TPH complex using three different docking algorithms such as HexDock,PatchDock and AutoDock.All these three algorithms showed that bacoside A and A3 well fit into the cavity consists of active sites.Further,our analysis revealed that major active compounds bacoside A3 and A interact with different residues of TPH through hydrogen bond.Interestingly,Tyr235,Thr265 and Glu317 are the key residues among them,but none of them are either at tryptophan or BH4 binding region.However,its note worthy to mention that Tyr 235 is a catalytic sensitive residue,Thr265 is present in the flexible loop region and Glu317 is known to interacts with Fe.Interactions with these residues may critically regulate TPH function and thus serotonin synthesis.Our study suggested that the interaction of bacosides(A3/A)with TPH might up-regulate its activity to elevate the biosynthesis of 5-HT,thereby enhances learning and memory formation.