L-Ornithine

Minimal hepatic encephalopathy (MHE), a complex neuropsychological complication of cirrhosis, is characterized by delayed reaction time and the inhibition of abnormal response. This network meta-analysis (NMA) was adopted to compare the efficacy of five drugs including lactulose, probiotics, rifaximin, acetyl-L-carnitine (ALC), and L-Ornithine L-aspartate (LOLA) in the treatment of MHE. The Cochrane Library, PubMed, and Embase databases were searched for any existing entail on these five drugs from the inception to February 2018, including Randomized controlled trials (RCTs). The NMA of the five drugs, accounting for both direct and indirect comparisons to assess WMD (weighted mean difference) and SUCRA (surface under the cumulative ranking curves) was conducted. In total, 10 RTCS with 826 MHE patients met the inclusion criteria and were included in the NMA. The meta-analysis revealed that compared with placebo, lactulose, and probiotics had better efficacy in reducing ammonia serum levels and total SIP (Sickness Impact Profil) score; ALC had better efficacy in lowering serum level of ammonia and increasing the serum level of albumin; rifaximin and LOLA had better efficacy in reducing total SIP score. The results from SUCRA revealed that in terms of ammonia and albumin serums, ALC presented with the highest rankings when it comes to efficacy (serum ammonia: 87.2%; serum albumin: 92.25%). Hence, the key findings from the present study highly suggested that ALC had the best efficacy in the treatment of MHE patients. © 2018 Wiley Periodicals, Inc.

BACKGROUND: L-arginine and L-ornithine have previously shown limited short-term immunological benefits in the treatment of periodontitis. The aim of this study was to assess the extended efficacy and durability of the response to L-arginine or L-ornithine as adjuncts to periodontal therapy in adults with periodontitis. MATERIALS AND METHODS: In this study, 75 patients who previously received the course of L-arginine or L-ornithine as adjuncts to professional mechanical plaque removal (PMPR) during a preliminary randomized short-term part of a clinical trial (NCT05042024) were assessed clinically and immunologically (nested) after 12 months follow-up. The immunological assay included immunohistochemical identification of densities of CD68 + and CD163 + single-positive gingival macrophages. All patients did not receive new prescriptions or dietary changes and underwent personalized steps of periodontal treatment during observation. RESULTS: After one year, patients who received L-arginine or L-ornithine exhibited a significant reduction of sites with periodontal pocket depth of 4-5 mm compared to PMPR (p < 0.0001). L-ornithine was associated with BoP decreasing compared to PMPR and L-arginine (95 % CI of odds ratio [1.12-1.46], p = 0.0002; CI [0.72-0.94], p = 0.004), CD68 + and CD163 + macrophages density increasing compared to PMPR (p < 0.001) and L-arginine (p < 0.05). L-arginine resulted in increased density of CD68 + macrophages and elevated CD68 + /CD163 + ratio compared to the PMPR and L-ornithine; CI [0.41-0.63], p = 0.009, CI [1.45-2.72], p < 0.0001. CONCLUSION: After one year, L-ornithine supplementation demonstrated more pronounced clinical benefits than L-arginine, although both can modulate gingival CD68 + and CD163 + macrophages.

OBJECTIVE: To compare the efficacy and safety profile of arginine glutamate and L-ornithine-L-aspartate (LOLA) in treating mild hepatic encephalopathy (HE) and hyperammonemia in cirrhotic patients. METHODS: This single-center, open-label, non-inferiority, randomized controlled trial (RCT) enrolled patients aged 18-75 years with cirrhosis and mild HE. The patients were randomly allocated in the ratio of 1:1 using a randomization table to be treated with intravenous administration of arginine glutamate or LOLA for 7 days. The primary end-point was the clinical improvement of mild HE. Secondary end-points included post-treatment change in blood ammonia level and the time to complete the number connection test (NCT)-A. Adverse events and adverse drug reactions were documented. RESULTS: From July 2020 to June 2021, 108 cirrhotic patients with mild HE were included and randomized to receive either arginine glutamate or LOLA for 7 days. Clinical improvement was observed in 88.9% of the patients receiving arginine glutamate and 90.7% of those having LOLA (between-group difference -1.9%, 95% confidence interval -13.3% to 9.6%), indicating non-inferiority of arginine glutamate to LOLA. The two groups showed comparable reductions in blood ammonia levels and improvements in time to complete NCT-A. The rate of adverse events was similar between the two groups, with only four cases reported adverse drug reactions. CONCLUSIONS: Both regimens effectively alleviated mild HE symptoms and reduced ammonia levels. Arginine glutamate showed non-inferiority to LOLA in terms of clinical improvement, ammonia reduction, and time to complete NCT-A, with no significant adverse events. © 2025 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

Hepatic encephalopathy (HE), a morbid ordeal affecting chronic liver disease patients always insists for the search of a rational, superior & infallible agent beyond the time-proven standards i.e., Lactulose & Rifaximin. In this RCT, we compared the efficacy of intravenous (IV) L-ornithine-L-aspartate(LOLA) versus Oral LOLA in patients with chronic liver disease(CLD) enduring overt Hepatic Encephalopathy(OHE). 40 CLD patients with OHE were randomly assigned IV or oral LOLA in a 1:1 ratio. Patients were graded for HE and monitored for serum ammonia levels from day 1 to day 5. The aim was to compare IV versus oral LOLA efficacy in HE grades improvement and its correlation with ammonia levels. The study was registered with clinical trials registry-India, CTRI/2020/12/029943. Baseline characteristics of patients in both groups were similar. The mean difference in ammonia levels from day 1 to day 5 was 55.4 ± 32.58 µmol/L in the IV LOLA group and 60.75 ± 13.82 µmol/L in the oral LOLA group (p = 0.511). Significant reductions in ammonia levels were observed from day 1 to day 5 within each group (p < 0.001). HE grade & ammonia correlated positively in both groups. LOLA, regardless of administration route, has demonstrated efficacy in OHE. © 2024. The Author(s).

Hepatic encephalopathy (HE) is a serious neurocognitive complication of liver dysfunction, often associated with elevated plasma ammonia. Ornithine phenylacetate (OP), a potent ammonia scavenger, is being evaluated for the treatment of acute/overt HE. The pharmacokinetics and pharmacodynamics of OP in patients with HE were characterized in this phase IIb study (NCT01966419). Adult patients hospitalized with an overt HE episode, cirrhosis, and plasma ammonia above the upper limit of normal (ULN) who failed to improve after 48 hours' standard care were randomly assigned to continuous intravenous OP (10, 15, or 20 g/day, based on Child-Turcotte-Pugh score) or matching placebo for 5 days. Plasma levels of ornithine and phenylacetic acid (PAA) and plasma/urinary levels of phenylacetylglutamine (PAGN) (primary metabolite of PAA) were regularly assessed; plasma ammonia level was the primary pharmacodynamic variable. PAA demonstrated dose-dependent pharmacokinetics; ornithine and PAGN levels increased with dose. PAGN urinary excretion represented ~50%-60% of administered PAA across all doses. Mean reduction in plasma ammonia with OP at 3 hours postinfusion was significantly greater versus placebo (p = 0.014); and time to achieve plasma ammonia less than or equal to the ULN was significantly reduced (p = 0.028). Achievement of clinical response based on HE stage was associated with a greater reduction in mean plasma ammonia level (p = 0.009). OP effects on plasma ammonia were consistent with its proposed mechanism of action as a primary ammonia scavenger, with a significant association between reduced plasma ammonia and improvement in HE stage. OP should be further evaluated as a promising treatment for hyperammonemia in patients with overt HE. © 2022 Hadassah Medical Center. Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.

Comment in Hepatology. 2022 Apr;75(4):1065-1066. doi: 10.1002/hep.32306. Hepatology. 2022 Apr;75(4):1064-1065. doi: 10.1002/hep.32309. Hepatology. 2022 May;75(5):1078-1080. doi: 10.1002/hep.32319. Hepatology. 2022 Nov;76(5):E108-E109. doi: 10.1002/hep.32643. BACKGROUND AND AIMS: Data on the use of intravenous L-ornithine L-aspartate (LOLA) in the treatment of overt HE (OHE) is limited. We evaluated the role of intravenous LOLA in patients of cirrhosis with OHE grade III-IV. APPROACH AND RESULTS: In a double-blind randomized placebo-controlled trial, 140 patients were randomized to a combination of LOLA, lactulose, and rifaximin (n = 70) or placebo, lactulose, and rifaximin (n = 70). LOLA was given as continuous intravenous infusion at a dose of 30 g over 24 h for 5 days. Ammonia levels, TNF-α, ILs, and endotoxins were measured on days 0 and 5. The primary outcome was the improvement in the grade of HE at day 5. Higher rates of improvement in grade of HE (92.5% vs. 66%, p < 0.001), lower time to recovery (2.70 ± 0.46 vs. 3.00 ± 0.87 days, p = 0.03), and lower 28-day mortality (16.4% vs. 41.8%, p = 0.001) were seen in the LOLA group as compared with placebo. Levels of inflammatory markers were reduced in both groups. Significantly higher reductions in levels of blood ammonia, IL-6, and TNF-α were seen in the LOLA group. CONCLUSIONS: Combination of LOLA with lactulose and rifaximin was more effective than only lactulose and rifaximin in improving grades of HE, recovery time from encephalopathy, with lower 28-day mortality. © 2021 American Association for the Study of Liver Diseases.

OBJECTIVE: To observe the effect of acupuncture combined with rehabilitation training on cognitive function and amino acid metabolism in children with cerebral palsy. METHODS: Twenty children with cerebral palsy (cerebral palsy group) were randomly divided into an acupuncture and rehabilitation group (11 cases) and a rehabilitation group (9 cases), and 10 healthy children were included as the normal group. The rehabilitation group was treated with rehabilitation training, 30 min each time; on the basis of rehabilitation training, the acupuncture and rehabilitation group was treated with acupuncture at Sishenzhen, Zhisanzhen, Naosanzhen, Niesanzhen, Dazhui (GV 14), Shenzhu (GV 12), Mingmen (GV 4), etc. The Sishenzhen (left and right points) and the ipsilateral Niesanzhen were respectively connected with a group of electrodes, intermittent wave, frequency of 2 Hz for 30 min. Both groups were treated once every other day, three times a week, totaling for 3 months. The Gesell developmental diagnostic scale (GESELL) was used to evaluate the developmental quotient (DQ) scores before and after treatment, and the blood samples of children with cerebral palsy before and after treatment and normal children were collected for amino acid metabolomics. RESULTS: Compared before treatment, the DQ scores of adaptation, fine motor and social in the acupuncture and rehabilitation group was increased after treatment (P<0.05), and the DQ score of fine motor in the rehabilitation group was increased after treatment (P<0.05). Compared with the normal group, the serum L-glutamate, L-ornithine, L-tyrosine, L-methionine and L-arginine in the cerebral palsy group were down-regulated, and L-histidine, L-citrulline, 5-hydroxylysine and L-glutamine were up-regulated before treatment. The functional pathways mapped by different metabolites between the cerebral palsy group and the normal group included arginine biosynthesis, arginine and proline metabolism, etc. Compared with the cerebral palsy group, the serum L-histidine was decreased, and L-citrulline showed decreasing trend in the acupuncture and rehabilitation group after treatment. CONCLUSION: Acupuncture combined with rehabilitation tr

The transnasal route for the delivery of water-soluble macromolecules, such as bioactive peptides and proteins, has attracted interest, although the use of permeation enhancers is required due to the poor permeabilities of these macromolecules across the nasal mucosa. With polycationic compounds, such as poly-L-arginine and chitosan, the nasal absorption of hydrophilic macromolecules is molecular weight- and concentration-dependently enhanced without causing cytotoxicity. In the present study, we evaluated the effect of various molecular weights and concentrations of poly-L-ornithine (PLO), a polycationic compound, on the nasal absorption and the damage to the nasal mucosa in vivo. PLO enhanced the nasal absorption of fluorescein isothiocyanate-dextran (FD-4), used as a model drug, and the bioavailability of FD-4 increased with the concentration of PLO. The enhancement effect was also dependent on the molecular weight. The administration of PLO at a concentration that sufficed for enhancing the nasal absorption had no effect on the activity of lactic dehydrogenase and the protein leakage in the nasal fluid, as indices of nasal mucosa damage. These findings suggest that a transnasal delivery system using PLO is a useful strategy for improving the nasal absorption of water-soluble macromolecules without toxicity to the nasal mucosa.

Microvesicle (MV) release from tumour cells influences drug retention, contributing to cancer drug resistance. Strategically regulating MV release may increase drug retention within cancer cells and allow for lower doses of chemotherapeutic drugs. The contribution of exosomes to drug retention still remains unknown. Potential exosome and MV (EMV) biogenesis inhibitors, tested on human prostate cancer (PC3) cells for their capacity to inhibit EMV release, were also tested on PC3 and MCF-7 (breast cancer) cells for improving chemotherapy. Agents inhibiting EMV release most significantly, whilst maintaining cell viability, were chloramidine (Cl-amidine; 50 µM) and bisindolylmaleimide-I (10 µM). Apoptosis mediated by the chemotherapy drug 5-fluorouracil (5-FU) was significantly enhanced in PC3 cells in the presence of both these EMV inhibitors, resulting in a 62% (Cl-amidine + 5-FU) and 59% (bisindolylmaleimide-I + 5-FU) decrease in numbers of viable PC3 cells compared to 5-FU alone after 24 h. For MCF-7 cells, there were similar increased reductions of viable cells compared to 5-FU treatment alone ranging from 67% (Cl-amidine + 5-FU) to 58% (bisindolylmaleimide-I + 5-FU). Using combinatory treatment, the two EMV inhibitors further reduced the number of viable cancer cells tested. Neither inhibitor affected cell viability. Combining selected EMV inhibitors may pose as a novel strategy to enhance the efficacy of chemotherapeutic drug-mediated apoptosis.

In this study, we elucidated the effect of poly(amino acid)s such as poly-L-ornithine (PLO) on FITC-insulin uptake in cultured alveolar type II epithelial cells, RLE-6TN. FITC-insulin uptake by RLE-6TN cells as well as its cell surface binding was markedly increased by PLO without cytotoxicity. The uptake of FITC-insulin in the presence of PLO was shown to be mediated by endocytosis, but in contrast to the uptake in the absence of PLO, the contribution of macropinocytosis emerged. Colocalization of FITC-insulin and LysoTracker Red was observed by confocal laser scanning microscopy both in the absence and presence of PLO, indicating that FITC-insulin was partly targeted to lysosomes in the cells and degraded. The half-life of the intracellular degradation of FITC-insulin was, however, prolonged by the presence of PLO. PLO also stimulated the uptake of other FITC-labeled compounds. Among them, the enhancement effects of PLO on FITC-albumin and FITC-insulin uptake were prominent. The effect of PLO on insulin absorption was also examined in in-vivo pulmonary administration in rats, and co-administration of PLO enhanced the hypoglycemic action of insulin. These findings suggest that co-administration of poly(amino acid)s such as PLO is a useful strategy for enhancing insulin uptake by alveolar epithelial cells and subsequent absorption from the lung.

Erratum in J Med Chem. 2011 Nov 24;54(22):7942. Protein arginine deiminase (PAD) activity is upregulated in a number of human diseases, including rheumatoid arthritis, ulcerative colitis, and cancer. These enzymes, there are five in humans (PADs 1-4 and 6), regulate gene transcription, cellular differentiation, and the innate immune response. Building on our successful generation of F- and Cl-amidine, which irreversibly inhibit all of the PADs, a structure-activity relationship was performed to develop second generation compounds with improved potency and selectivity. Incorporation of a carboxylate ortho to the backbone amide resulted in the identification of N-α-(2-carboxyl)benzoyl-N(5)-(2-fluoro-1-iminoethyl)-l-ornithine amide (o-F-amidine) and N-α-(2-carboxyl)benzoyl-N(5)-(2-chloro-1-iminoethyl)-l-ornithine amide (o-Cl-amidine), as PAD inactivators with improved potency (up to 65-fold) and selectivity (up to 25-fold). Relative to F- and Cl-amidine, the compounds also show enhanced potency in cellulo. As such, these compounds will be versatile chemical probes of PAD function.

Comment in Hepatology. 2009 Jul;50(1):3-5. doi: 10.1002/hep.23037. Treatment of hyperammonemia and hepatic encephalopathy in cirrhosis is an unmet clinical need. The aims of this study were to determine whether L-ornithine and phenylacetate/phenylbutyrate (administered as the pro-drug phenylbutyrate) (OP) combined are synergistic and produce sustained reduction in ammonia by L-ornithine acting as a substrate for glutamine synthesis, thereby detoxifying ammonia, and the phenylacetate excreting the ornithine-derived glutamine as phenylacetylglutamine in the urine. Sprague-Dawley rats were studied 4 weeks after bile duct ligation (BDL) or sham operation. Study 1: Three hours before termination, an internal carotid sampling catheter was inserted, and intraperitoneal saline (placebo), OP, phenylbutyrate, or L-ornithine were administered after randomization. BDL was associated with significantly higher arterial ammonia and brain water and lower brain myoinositol (P < 0.01, respectively), compared with sham-operated controls, which was significantly improved in the OP-treated animals; arterial ammonia (P < 0.001), brain water (P < 0.05), brain myoinositol (P < 0.001), and urinary phenylacetylglutamine (P < 0.01). Individually, L-ornithine or phenylbutyrate were similar to the BDL group. In study 2, BDL rats were randomized to saline or OP administered intraperitoneally for 6 hours or 3, 5, or 10 days and were sacrificed between 4.5 and 5 weeks. The results showed that the administration of OP was associated with sustained reduction in arterial ammonia (P < 0.01) and brain water (P < 0.01) and markedly increased arterial glutamine (P < 0.01) and urinary excretion of phenylacetylglutamine (P < 0.01) in each of the OP treated groups. CONCLUSION: The results of this study provide proof of the concept that L-ornithine and phenylbutyrate/phenylacetate act synergistically to produce sustained improvement in arterial ammonia, its brain metabolism, and brain water in cirrhotic rats.

Neuronal nitric oxide synthases (nNOS) is distributed throughout the central nervous system (CNS) and has been proposed to modulate neuronal activity in the nucleus tractus solitarii (NTS). Here, we investigated whether the activation of nNOS is involved in insulin-induced cardiovascular responses in the NTS. Insulin (100 IU/ml) was unilaterally microinjected into the NTS, and the cardiovascular effects were evaluated before and after microinjection of the nNOS inhibitors 7-nitroindazole (7-NI) (5 pmol) and N(5)-(1-imino-3-butenyl)-l-ornithine (vinyl-L-NIO) (600 pmol). Western blot and immunohistochemical analyses were performed to determine nNOS phosphorylation levels after insulin or phosphoinositide 3-kinase (PI3K) inhibitor LY294002 microinjection into the NTS. Unilateral microinjection of insulin into the NTS produced prominent depressor and bradycardic effects in WKY rats. Pretreatment with the nNOS inhibitors 7-NI and Vinyl-L-NIO attenuated the cardiovascular response evoked by insulin in Wistar-Kyoto (WKY) rats. Moreover, Western blot analysis showed a significant increase in nNOS (16.5+/-0.4-fold; P<0.05; n=4) phosphorylation after insulin injection, whereas the PI3K inhibitor LY294002 abolished the insulin-induced effects. In situ nNOS phosphorylation was found to be increased in the NTS after insulin injection. Furthermore, co-immunoprecipitation assay showed Akt and nNOS can bind to each other as detected by phospho-Akt(S473) and phospho-nNOS(S1416) antibodies. In vitro kinase assay showed insulin activated Akt can directly phosphorylate nNOS(S1416). These results demonstrated that nNOS may couple with the activation of the insulin receptor, via the liberation of NO, in order to participate in central cardiovascular regulation of WKY rats.

Nonselective inhibition of nitric oxide (NO) synthase (NOS) augments myogenic autoregulation, an action that implies enhancement of pressure-induced constriction and dilatation. This pattern is not explained solely by interaction with a vasoconstrictor pathway. To test involvement of the Rho-Rho kinase pathway in modulation of autoregulation by NO, the selective Rho kinase inhibitor Y-27632 and/or the NOS inhibitor N(omega)-nitro-l-arginine methyl ester (l-NAME) were infused into the left renal artery of anesthetized rats. Y-27632 and l-NAME were also infused into isolated, perfused hydronephrotic kidneys to assess myogenic autoregulation over a wide range of perfusion pressure. In vivo, l-NAME reduced renal vascular conductance and augmented myogenic autoregulation, as shown by increased slope of gain reduction and associated phase peak in the pressure-flow transfer function. Y-27632 (10 mumol/l) strongly dilated the renal vasculature and profoundly inhibited autoregulation in the absence or presence of l-NAME in vivo and in vitro. Afferent arteriolar constriction induced by 30 mmol/l KCl was reversed (-92 +/- 3%) by Y-27632. Phenylephrine caused strong renal vasoconstriction but did not affect autoregulation. Inhibition of neuronal NOS by N(5)-(1-imino-3-butenyl)-l-ornithine (l-VNIO) did not cause significant vasoconstriction but did augment myogenic autoregulation. Thus vasoconstriction is neither necessary (l-VNIO) nor sufficient (phenylephrine) to explain the augmented myogenic autoregulation induced by l-NAME. The effect of l-VNIO implicates tubuloglomerular feedback (TGF) and neuronal NOS at the macula densa in regulation of the myogenic mechanism. This conclusion was confirmed by the demonstration that systemic furosemide removed the TGF signature from the pressure-flow transfer function and significantly inhibited myogenic autoregulation. In the presence of furosemide, augmentation of myogenic autoregulation by l-NAME was significantly reduced. These results provide a potential mechanism to explain interaction between myogenic and TGF-mediated autoregulation.

The purpose of the present study was to examine the possibility of using molecularly imprinted polymers (MIPs) to screen for bitterness-suppressing agents. Quinine was selected as the bitter substance standard. L-arginine (L-Arg), L-ornithine (L-Orn), L-lysine (L-Lys), and L-citrulline (L-Ctr) were tested as bitterness suppressant candidates. In a high-performance liquid chromatography study using a uniformly sized MIP for cinchonidine, which has a very similar structure to quinine, the retention factor (k) of quinine was significantly shortened by the addition of L-Arg or L-Orn to the mobile phase, whereas slight or no decrease was observed when L-Ctr and L-Lys were added. The abilities of these amino acids to decrease the k of quinine were ranked in the following order: L-Arg = (L-Orn >(L-Ctr >>(L-Lys. A linear relationship between the reciprocal of k and the concentration of the amino acids indicated a single competitive model at a single site. The magnitude of the association constants obtained seemed to be directly related to the inhibitory effect of the test substances on the affinity of quinine for the receptor site. Nuclear magnetic resonance and molecular modeling studies suggested a one-to-two hydrogen-bonding-based complex formation of one quinine molecule with two methacrylic acid molecules (Q-2MAA) in chloroform. In the molecular modeling studies, the N--N distance of the quinine molecule in the assumed Q-2MAA complex was calculated to be 5.12 angstroms, similar to the N - N distances of the two amino acid complexes (L-Arg-2MAA, L-Orn-2MAA), which were 4.84 and 5.30 angstroms, respectively. This suggests that L-Arg and L-Orn may compete with the quinine molecule in the cinchonidine-imprinted space. Finally, the results of human gustatory sensation tests correlated well with the MIP data. The proposed method using MIPs seems to have a potential for screening bitterness-suppressing agents for quinine. Copyright 2004 Wiley-Liss, Inc.

PURPOSE: The aim of this study was to explore the feasibility of improvement of ocular bioavailability of the antiviral agent acyclovir by designing amino acid prodrugs targeted to the amino acid transporters on the rabbit cornea. MATERIALS AND METHODS: Transcorneal flux of two water-soluble amino acid ester prodrugs of acyclovir (ACV), gamma-glutamate-ACV (EACV) and L-tyrosine-ACV (YACV), was studied across freshly excised rabbit cornea. Chemical and enzymatic hydrolysis studies of the two prodrugs were also conducted. RESULTS: EACV inhibited the uptake of [(3)H]L-Arg in rabbit primary corneal epithelial cells (rPCECs). The compound also exhibited longer half-life (t(1/2)) in cornea in comparison to YACV. Transcorneal flux of EACV was observed to be concentration-, energy-, and sodium-dependent and independent of pH within the range studied. EACV transport was inhibited by neutral and cationic amino acids, L-ornithine (specific for cationic amino acids), and BCH (2-aminobicyclo-[2,2,1]-heptane-2-carboxylic-acid) (specific inhibitor for L-type system and B(0,+) system). On the other hand, YACV was not recognized by this amino acid transporter as it failed to inhibit the uptake of [(3)H]Arg, and also its transport across cornea was not inhibited by arginine. YACV and EACV exhibited excellent antiviral activity against HSV-1 and 2 and Varicella-Zoster Virus (VZV) in comparison to ACV. CONCLUSIONS: Analyses of the inhibition pattern of EACV transport suggests the involvement of a single transport system; namely, B(0,+). Design of amino acid prodrugs seems to be an attractive strategy to enhance the solubility of the otherwise poorly aqueous soluble compounds and also to afford a targeted and possibly enhanced delivery of the active drug.

Recently, we demonstrated that the diffusible messenger molecule nitric oxide (NO) is involved in the hyperthermic response induced by morphine by using a nonselective nitric-oxide synthase inhibitor, N-nitro-L-arginine methyl ester. The present work extended these studies to include 7-nitroindazole (7-NI), an inhibitor specific for neuronal nitric-oxide synthase (nNOS), N(5)-(-iminoethyl)-L-ornithine (L-NIO), an inhibitor of endothelial NOS (eNOS), and aminoguanidine (AG), a potent inhibitor of inducible NOS (iNOS). A biotelemetry system was used in this study to measure the body temperature (Tb). A dose of 7-NI (5 or 10 mg/kg), which did not affect Tb by itself, blocked the hyperthermia induced by morphine in a dose-dependent manner (15 mg/kg i.p.). However, pretreatment with L-NIO (10-20 mg/kg) or with AG (50 mg/kg) failed to alter the hyperthermia induced by morphine. L-NIO (10-20 mg/kg) or AG (50 mg/kg) had no effect on Tb. These results suggest the involvement of nNOS in morphine-induced hyperthermia.

BACKGROUND AND OBJECTIVE: L-Ornithine phenylacetate is an intravenous formulation of the L-ornithine salt of phenylacetic acid under development for the treatment of hepatic encephalopathy. Very limited clinical data in patients are available, with a phase II study in target patients not designed for dose finding, to support phase III dose selection in a global development program. The objective of the present population pharmacokinetic modeling and simulation was to evaluate dose selection for target patient populations with a low body weight, ethnicity, and hepatic impairment in a global clinical study. METHODS: A population pharmacokinetic model was developed based on plasma concentrations of L-ornithine, phenylacetic acid, and phenylacetylglutamine data from four clinical trials in healthy subjects and patients with stable cirrhosis or hospitalized adult patients with liver cirrhosis and hepatic encephalopathy. A covariate analysis was conducted to identify source of variability to support dose selection for global clinical development of L-ornithine phenylacetate. Phenylacetylglutamine formation in the pharmacokinetic model also quantified pharmacodynamic effects measured by ammonia removal. RESULTS: Body weight and hepatic function were significant covariates determining phenylacetic acid exposure. After accounting for body weight, there was no difference between tested Caucasian and Asian populations in phenylacetic acid exposure. Renal dysfunction significantly reduced phenylacetylglutamine excretion. However, renal impairment had no impact on plasma phenylacetic acid and free ammonia levels. Exploratory modeling suggested that L-ornithine might enhance the removal of ammonia. CONCLUSIONS: With a flat dosing algorithm, special consideration must be given to patients with a small body size (i.e., body weight ≤ 50 kg) and severe hepatic impairment. © 2021. The Author(s).

In mammals, daily physiological events are regulated by the circadian rhythm, which comprises two types of internal clocks: the central clock and peripheral clocks. Circadian rhythm plays an important role in maintaining physiological functions including the sleep-wake cycle, body temperature, metabolism and organ functions. Circadian rhythm disorder, which is caused, for example, by an irregular lifestyle or long-haul travel, increases the risk of developing disease; therefore, it is important to properly maintain the rhythm of the circadian clock. Food and the circadian clock system are known to be closely linked. Studies on rodents suggest that ingesting specific food ingredients, such as the flavonoid nobiletin, fish oil, the polyphenol resveratrol and the amino acid L-ornithine affects the circadian clock. However, there are few reports on the foods that affect these circadian clocks in humans. In this study, therefore, we examined whether L-ornithine affects the human central clock in a crossover design placebo-controlled human trial. In total, 28 healthy adults (i.e. ≥20 years) were randomly divided into two groups and completed the study protocol. In the 1st intake period, participants were asked to take either L-ornithine (400 mg) capsules or placebo capsules for 7 days. After 7 days' interval, they then took the alternative test capsules for 7 days in the 2nd intake period. On the final day of each intake period, saliva was sampled at various time points in the dim light condition, and the concentration of melatonin was quantified to evaluate the phase of the central clock. The results revealed that dim light melatonin onset, a recognized marker of central circadian phase, was delayed by 15 min after ingestion of L-ornithine. Not only is this finding an indication that L-ornithine affects the human central clock, but it also demonstrates that the human central clock can be regulated by food ingredients.

INTRODUCTION: While hyperammonemia is traditionally associated with decompensated cirrhosis, emerging evidence suggests that disturbances in nitrogen homeostasis contribute to disease progression in earlier stages of steatohepatitis and fibrosis. L-ornithine L-aspartate (LOLA), an established ammonia scavenger, targets key pathophysiological mechanisms shared by metabolic dysfunction-associated steatotic liver disease (MASLD), including oxidative stress, mitochondrial dysfunction and hepatic stellate cell activation. This systematic review synthesizes current experimental and clinical research to evaluate the potential therapeutic role of LOLA in MASLD. METHODS: A systematic search of PubMed, Embase and SCOPUS was conducted up to December 1, 2025, following PRISMA 2020 guidelines. Eligible studies included experimental (in vivo/in vitro) and clinical trials evaluating the effects of LOLA or L-aspartate on hepatic steatosis, inflammation, or fibrosis in the context of MASLD. Data extraction and quality assessment were performed independently by two reviewers using appropriate tools for animal and human studies. RESULTS: Nineteen studies were included, comprising 10 experimental pre-clinical models (9 in vivo animal studies and 1 in vitro study) and 9 clinical studies involving approximately 1671 participants. Experimental studies consistently demonstrated that LOLA intervention ameliorates hepatic steatosis, inflammation and collagen deposition. Identified molecular mechanisms included the activation of the LKB1-AMPK axis, restoration of mitochondrial bioenergetics and modulation of the gut-liver-muscle axis. In clinical studies, results from three randomized controlled trials (RCTs) indicated significant improvements in liver enzymes (ALT, AST) and lipid profiles, with reductions in hepatic steatosis. Evidence from six observational and open-label studies corroborated these biochemical improvements and further demonstrated significant reductions in blood ammonia levels, improved intrahepatic microcirculation and reduced liver stiffness and patient-reported fatigue. However, clinical evidence remains limited by study heterogeneity and a lack of large-scale random

Update of doi: 10.1002/14651858.CD012734. RATIONALE: Hepatic encephalopathy is a common complication of cirrhosis. Its development is associated with increased morbidity and mortality. Its exact pathogenesis is unknown, but ammonia, produced by bacterial action in the intestine, plays a key role. Antibiotics modulate the gut flora and may reduce intestinal ammonia production. Aminoglycosides such as neomycin, paromomycin, and ribostamycin have been used to treat hepatic encephalopathy, as have other antibiotics such as vancomycin and metronidazole. OBJECTIVES: To assess the beneficial and harmful effects of aminoglycosides, vancomycin, and metronidazole versus placebo, no intervention, other antibiotics, or other active pharmacological interventions, for the prevention and treatment of hepatic encephalopathy in people with cirrhosis. SEARCH METHODS: We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, and three other databases to 15 April 2025. We also searched online trials registries for ongoing and unpublished trials, undertook manual searches of meeting and conference proceedings, checked bibliographies of relevant articles, and corresponded with investigators and pharmaceutical companies. ELIGIBILITY CRITERIA: We included randomised clinical trials (RCTs) involving participants with cirrhosis and hepatic encephalopathy, or who were at risk of developing hepatic encephalopathy, comparing aminoglycosides, vancomycin, or metronidazole to (1) placebo or no intervention; or (2) other pharmacological agents, including non-absorbable disaccharides, other antibiotics, or other potentially beneficial agents (e.g. branched-chain amino acids, L-ornithine L-aspartate, nitazoxanide (a broad-spectrum antiparasitic/antiviral agent), and nicotinohydroxamic acid (a potent urease inhibitor). We included trials irrespective of publication status, outcomes reported, language, or blinding. We excluded trials involving people with hepatic encephalopathy associated with acute liver failure or with non-cirrhotic portal hypertension. OUTCOMES: The critical outcomes were all-cause mortality, hepatic encephalopathy, and serious adverse

L-Ornithine (L-Orn) is a nonessential amino acid but has many physiological roles. Accordingly, L-Orn has been used as a functional food or dietary supplement to ameliorate various maladies, but there is only limited information available about its safety. The safety of a chemical compound is generally assessed via non-clinical and clinical studies, but safety information derived from human studies is particularly important. Recently, systematic reviews have been used to assess the safety as well as the effectiveness and usefulness of such studies. Therefore, we conducted an assessment of the safety of L-Orn by systematically reviewing clinical studies. Specifically, we performed a comprehensive search of databases for clinical trials in which L-Orn was added to ordinary diets (i.e., orally administered) in healthy individuals. Focusing on PubMed, Cochrane Library, Ichushi-Web, and EBSCOhost, we comprehensively searched for reports on human studies on the oral ingestion of L-Orn. We identified 22 articles as subjects for this SR. Among these articles, the maximum L-Orn dose was 14,025 mg/person/day in the form of L-Orn hydrochloride and the maximum duration of administration was 156 days. The main observed adverse events were gastrointestinal disorders. Indexing these adverse events, the no observed adverse effect level was estimated to be 12,000 mg/person/day for L-Orn in the form of L-Orn hydrochloride. When we conducted an integration analysis on the risk of adverse events, the difference between those with and without L-Orn supplementation in the risk of gastrointestinal disorders was 0.00 (95% confidence interval: ±0.02, P = 1.00), so no significant effects were observed. (UMIN000033371). © 2025. The Author(s).

BACKGROUND AND STUDY AIMS: Minimal hepatic encephalopathy (MHE) is an early stage of hepatic encephalopathy (HE) and is highly prevalent. The efficacy of L-ornithine L-aspartate (LOLA) for the treatment of HE is well known but its role in MHE remains uncertain. The objectives of the current study were to evaluate the efficacy of LOLA for the treatment of MHE in patients with cirrhosis. METHODS: The Cochrane Library, PubMed, EMBASE, Web of Science and Ovid databases were searched. Only randomized controlled trials (RCTs) that compared the efficacy of LOLA with placebo or no intervention for the treatment of MHE in patients with cirrhosis were included from inception to January 2023. The primary outcomes were reversal of MHE and development of overt hepatic encephalopathy (OHE). RESULTS: Overall, six RCTs comprising 292 patients were included. Compared with placebo or no intervention, LOLA was more effective in reversing MHE (RR = 2.264, 95 % CI = 1.528, 3.352, P = 0.000, I2 = 0.0 %) and preventing progression of OHE (RR = 0.220, 95 % CI = 0.076, 0.637, P = 0.005, I2 = 0.0 %). Based on subgroup analyses, oral LOLA treatment appeared more likely to reverse MHE (RR = 2.648, 95 % CI = 1.593, 4.402, P = 0.000, I2 = 0.0 %), intravenous LOLA treatment yielded a similar probability of reversing MHE (RR = 1.669, 95 % CI = 0.904, 3.084, P = 0.102, I2 = 0.0 %). LOLA did not show a superior possibility in reducing mortality (RR = 0.422, 95 % CI = 0.064, 2.768, P = 0.368, I2 = 0.0 %) and ammonia levels (SMD = 0.044, 95 % CI = -0.290, 0.379, P = 0.795, I2 = 0.0 %) compared with placebo or no intervention. CONCLUSIONS: LOLA has significant beneficial effects on reversal of MHE and prevention of OHE in patients with cirrhosis compared with placebo or no intervention.

BACKGROUND: Transjugular intrahepatic portosystemic shunt (TIPS) can be an effective treatment for cirrhotic patients who develop variceal bleeding and ascites. However, TIPS placement is associated with an increased risk of developing hepatic encephalopathy (HE). Recently, there have been efforts to use the typical medical therapies prophylactically in patients undergoing TIPS placement to prevent post-TIPS HE. METHODS: We conducted literature searches in MEDLINE, Embase, CINAHL, Scopus, and Cochrane to examine studies that use prophylactic medical therapy for preventing post-TIPS HE. A narrative synthesis and grading of recommendations assessment assessment were done for all studies. Meta-analysis was performed for eligible studies using the Mantel-Haenszel method random-effects model. Nine hundred twenty-one articles were screened and 5 studies were included in the study after 2 levels of screening. The medications studied were rifaximin, lactulose, lactitol, L-Ornithine-L-aspartate (LOLA), albumin, and combination therapies. RESULTS: Narrative results showed that lactulose, lactitol, LOLA and albumin prophylaxis were not associated with reduction in HE occurrence or mortality. A combination of rifaximin and lactulose was found to be associated with lower occurrence of HE, and the results were not different when LOLA was added. Meta-analysis (n = 3) showed that rifaximin treatment was not associated with changes in HE occurrences. CONCLUSION: In conclusion, a vast majority of medications were not found to be effective post-TIPS HE prophylaxis when used alone. A rifaximin and lactulose combination therapy may be beneficial. Overall, there is significant limitation in the current data and more studies are needed to yield more robust meta-analysis results in the future. Neutrophil Extracellular Traps (NETs) and Vasculitis. Arneth B(1), Arneth R(2). Author information: (1)Institute of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, University Hospital of the Universities of Giessen and Marburg UKGM, Justus Liebig University Giessen, Giessen, Germany. (2)Clinic of Nephrology, Internal Medicine, University Hospital of the Universities of Giesse

38. Int J Med Sci. 2021 Feb 3;18(7):1532-1540. doi: 10.7150/ijms.53728. eCollection 2021. Neutrophil Extracellular Traps (NETs) and Vasculitis. Arneth B(1), Arneth R(2). Author information: (1)Institute of Laboratory Medicine and Pathobiochemistry, Molecular Diagnostics, University Hospital of

BACKGROUND & AIMS: We aimed to synthesize evidence for most effective treatments for minimal hepatic encephalopathy (HE) and prevention of overt HE in patients with cirrhosis. METHODS: We performed a systematic search of the PubMed, EMBASE, OvidSP, and Cochrane Central Register of Controlled Trials databases through July 26, 2018, for randomized controlled trials evaluating treatments for minimal HE in patients with cirrhosis, with primary outcomes of reversal of minimal HE or prevention of overt HE. We conducted a meta-analysis and then used network meta-analysis and surface under cumulated ranking (SUCRA) to pool the direct and indirect estimates and rank the different treatments. We appraised study quality using the Grading of Recommendations Assessment, Development and Evaluation system. RESULTS: Our meta-analysis and network meta-analysis included 25 trials, comprising 1563 participants. Agents found to be effective in reversing minimal HE compared with placebo or no treatment included rifaximin (odds ratio [OR], 7.53; 95% predictive interval [PrI], 4.45-12.73; SUCRA, 89.2%; moderate quality), lactulose (OR, 5.39; 95% PrI, 3.60-8.0; SUCRA, 67.2%; moderate quality), the combination of probiotics and lactulose (OR, 4.66; 95% PrI, 1.90-11.39; SUCRA, 52.4%; low quality), L-ornithine L-aspartate (OR, 4.45; 95% PrI, 2.67-7.42; SUCRA, 47.2%; low moderate quality), and probiotics (OR, 3.89; 95% PrI, 2.52-6.02; SUCRA, 34.1%; low quality). Agents found to be effective in preventing episodes of overt HE compared with placebo or no treatment included L-ornithine L-aspartate (OR, 0.19; 95% PrI, 0.04-0.91; SUCRA, 75.1%; high moderate quality), lactulose (OR, 0.22; 95% PrI, 0.09-0.52; SUCRA, 73.9%; moderate quality), and probiotics (OR, 0.27; 95% PrI, 0.11-0.62; SUCRA, 59.6%; low quality). CONCLUSIONS: In a meta-analysis of data from 25 trials, we found rifaximin and lactulose to be most effective for reversal of minimal HE in patients with cirrhosis. L-ornithine L-aspartate and lactulose are most effective in the prevention of overt HE. Lactulose was the only agent that was effective in reversing minimal HE, preventing overt HE, reducing ammonia, and improving quality of

The present systematic review with meta-analysis was undertaken to review the evidence base in support of a beneficial effect of L-ornithine L-aspartate (LOLA) for the prevention/prophylaxis of overt hepatic encephalopathy (OHE) in patients with cirrhosis. Using appropriate keywords and electronic and manual searches together with established inclusion/exclusion criteria, six randomized controlled trials (RCTs) for a total of 384 patients were identified five of which were of high quality and low risk of bias according to Jadad-Cochrane criteria. Treatment with LOLA resulted in significant reductions in the risk of progression to OHE in MHE patients (3 studies) with RR: 0.23 [95% CI: 0.07, 0.73], p < 0.01. LOLA was also effective for secondary OHE prophylaxis with RR: 0.389 [95% CI: 0.174-0.870] p < 0.002 as well as for primary prophylaxis for OHE following acute variceal bleeding [RR: 0.42 [95% CI: 0.16-0.98] p < 0.03 and for OHE prophylaxis post-TIPSS [RR: 0.30 [95% CI: 0.03-2.66] compared to placebo/no intervention in all cases. OHE prevention/prophylaxis was accompanied by significant reductions of blood ammonia. Both oral and intravenous formulations of LOLA appeared to be effective for the prevention of progression to OHE in patients with MHE. These findings provide the first direct evidence of potential benefit of LOLA for the prevention of OHE in cirrhosis across a range of clinical presentations.

Minimal hepatic encephalopathy has been shown to increase risk of involvement in road traffic accidents and alter quality of life. This systematic review focused on the role of nonabsorbable disaccharides for the management of minimal hepatic encephalopathy. Randomized clinical trials that evaluated medical management of minimal hepatic encephalopathy were considered for inclusion. Individual studies compared lactulose with usual care and lactulose with probiotics and L-ornithine-L-aspartate. The outcome for examination was the neuropsychiatric test for cognitive function. Search strategies outlined by the Johanna Briggs Institute were used, and articles and references of selected articles were reviewed according to that methodology. Meta-analyses and narrative synthesis of the included studies were undertaken. Treatment of minimal hepatic encephalopathy with lactulose, probiotics, or L-ornithine-L-aspartate was seen to be equally effective in reducing abnormal tests at 1, 3, and 12 months post-treatment. All patients with minimal hepatic encephalopathy should be screened using a neuropsychiatric test and receive treatment as needed. Treatment can delay or eliminate risky automobile accidents and harm to self. Lactulose, probiotics, and L-ornithine-L-aspartate are a low-cost alternative compared with antibiotic treatment.

BACKGROUND: Hepatic encephalopathy is a common complication of cirrhosis and has high associated morbidity and mortality. The condition is classified as overt if it is clinically apparent or minimal if only evident though psychometric testing. The exact pathogenesis of this syndrome is unknown although ammonia is thought to play a key role. L-ornithine L-aspartate has ammonia-lowering properties and may, therefore, benefit people with cirrhosis and hepatic encephalopathy. OBJECTIVES: To evaluate the beneficial and harmful effects of L-ornithine L-aspartate versus placebo, no intervention, or other active interventions in people with cirrhosis and hepatic encephalopathy. SEARCH METHODS: We undertook electronic searches of The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, LILACS and Science Citation Index Expanded to December 2017 and manual searches of meetings and conference proceedings; checks of bibliographies; and corresponded with investigators and pharmaceutical companies. SELECTION CRITERIA: We included randomised clinical trials, irrespective of publication status, language, or blinding. We included participants with cirrhosis who had minimal or overt hepatic encephalopathy or who were at risk for developing hepatic encephalopathy. We compared: L-ornithine L-aspartate versus placebo or no intervention; and L-ornithine L-aspartate versus other active agents such as non-absorbable disaccharides, antibiotics, probiotics, or branched-chain amino acids. DATA COLLECTION AND ANALYSIS: Two review authors, working independently, retrieved data from published reports and correspondence with investigators and pharmaceutical companies. The primary outcomes were mortality, hepatic encephalopathy, and serious adverse events. We undertook meta-analyses and presented the results as risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CI). We assessed bias control using the Cochrane Hepato-Biliary Group domains; we evaluated the risk of publication bias and other small trial effects in regression analyses; conducted subgroup and sensitivity analyses; and performed Trial Sequential Analyses. We determined the quali