Polyethyleneimine facilitates the growth and electrophysiological characterization of iPSC-derived motor neurons.

Induced pluripotent stem cell (iPSC) technology, in combination with electrophysiological characterization via multielectrode array (MEA), has facilitated the utilization of iPSC-derived motor neurons (iPSC-MNs) as highly valuable models for underpinning pathogenic mechanisms and developing novel therapeutic interventions for motor neuron diseases (MNDs). However, the challenge of MN adherence to the MEA plate and the heterogeneity presented in iPSC-derived cultures raise concerns about the reproducibility of the findings obtained from these cellular models. We discovered that one novel factor modulating the electrophysiological activity of iPSC-MNs is the extracellular matrix (ECM) used in the coating to support in vitro growth, differentiation and maturation of iPSC-MNs. The current study showed that two coating conditions, namely, Poly-L-ornithine/Matrigel (POM) and Polyethyleneimine (PEI) strongly promoted attachment of iPSC-MNs on MEA culture dishes compared to three other coating conditions, and both facilitated the maturation of iPSC-MNs as characterized by the detection of extensive electrophysiological activities from the MEA plates. POM coating accelerated the maturation of the iPSC-MNs for up to 5 weeks, which suits modeling of neurodevelopmental disorders. However, the application of PEI resulted in more even distribution of the MNs on the culture dish and reduced variability of electrophysiological signals from the iPSC-MNs in 7-week cultures, which permitted the detection of enhanced excitability in iPSC-MNs from patients with amyotrophic lateral sclerosis (ALS). This study provides a comprehensive comparison of five coating conditions and offers POM and PEI as favorable coatings for in vitro modeling of neurodevelopmental and neurodegenerative disorders, respectively.

Effects of L-Ornithine-L-Aspartate on Angiogenesis and Perfusion in Subacute Hind Limb Ischemia: Preliminary Study.

The current treatment options for peripheral arterial disease (PAD) are limited due to a lack of significant high-level evidence to inform clinical decisions and unfavorable outcomes in terms of cost-effectiveness and amputation rates. In order to suggest the use of the commercially available L-Ornithine-L-Aspartate (LOLA) for treating PAD, we induced hind limb ischemia (HLI) by unilaterally ligating the femoral artery in a rat model. The rats were randomly divided into three groups, with seven rats assigned to each group: group 1 (control), group 2 (sorbitol), and group 3 (LOLA). Intraperitoneal injections were administered five times on post-operative days (PODs) 3, 5, 7, 10, and 12. Perfusion imaging was conducted on PODs 7 and 14 and compared to pre-operative perfusion imaging. Immunohistochemistry staining and Western blotting were performed after the final perfusion imaging. Group 3 showed a significant increase in perfusion, high CD31-positive capillary lumen density, and substantial overexpression of VEGF in the ischemic limb during the subacute phase of HLI. In conclusion, this study provides the first documented evidence of angiogenesis and perfusion recovery in the subacute phase of the HLI model following the administration of LOLA. With LOLA readily available on the commercial market, the implementation of LOLA treatment for PAD in humans can be expedited compared to other therapies still in the developmental stage.

Biotechnological application of Aureobasidium spp. as a promising chassis for biosynthesis of ornithine-urea cycle-derived bioproducts.

The ornithine-urea cycle (OUC) in fungal cells has biotechnological importance and many physiological functions and is closely related to the acetyl glutamate cycle (AGC). Fumarate can be released from argininosuccinate under the catalysis of argininosuccinate lyase in OUC which is regulated by the Ca2+ signaling pathway and over 93.9 ± 0.8 g/L fumarate can be yielded by the engineered strain of Aureobasidium pullulans var. aubasidani in the presence of CaCO3. Furthermore, 2.1 ± 0.02 mg of L-ornithine (L-Orn)/mg of the protein also can be synthesized via OUC by the engineered strains of Aureobasidum melanogenum. Fumarate can be transformed into many drugs and amino acids and L-Orn can be converted into siderophores (1.7 g/L), putrescine (33.4 g/L) and L-piperazic acid (L-Piz) (3.0 g/L), by different recombinant strains of A. melanogenum. All the fumarate, L-Orn, siderophore, putrescine and L-Piz have many applications. As the yeast-like fungi and the promising chassis, Aureobasidium spp, have many advantages over any other fungal strains. Further genetic manipulation and bioengineering will enhance the biosynthesis of fumarate and L-Orn and their derivates.

OUC in fungal cells has biotechnological importance and many physiological functions; OUC is closely related to acetyl glutamate cycle (AGC). Fumarate, L-Orn, siderophore, putrescine and L-Piz produced from OUC have many applications.

Intravenous versus oral 'L-ornithine-L-aspartate' in overt hepatic encephalopathy: a randomized comparative study.

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.

Prophylaxis of hepatic encephalopathy: current and future drug targets.

Hepatic encephalopathy is described by a broad spectrum of neurological and psychiatric aberrations resulting due to advanced liver dysfunction. It is a neurological disorder due to hepatic insufficiency and/or portosystemic shunts. Its clinical presentation includes neuropsychiatric dysfunction ranging from subclinical changes to comatose state. It is a sign of poor prognosis in cirrhotics with a high 1-year mortality. Each episode of hepatic encephalopathy leads to high hospitalization rate, poor prognosis and raised burden of healthcare. Primary prophylaxis is prevention of initial occurrence and secondary prophylaxis is prevention of reappearance of hepatic encephalopathy in subjects who had prior history. Early detection and management of triggers is very important in the treatment of hepatic encephalopathy. The initial choice of treatment is still lactulose, as it is effective in minimal, overt, and recurrent hepatic encephalopathy. Rifaximin is equally effective as lactulose in managing hepatic encephalopathy and is better tolerated. Branch chain amino acids are beneficial in subjects who are protein intolerant. L-ornithine L-aspartate and probiotics are also useful in the management of hepatic encephalopathy. Rifaximin along with lactulose is effective in managing overt and recurrent hepatic encephalopathy. Large portosystemic shunts embolization and liver transplant is efficacious in certain group of patients. Nutritional therapy and fecal microbiota transplantation are newer therapies for hepatic encephalopathy but the evidences are limited, more research is required to prove their efficacy. Involvement of hospital pharmacists, telemedicine, and providing education are also beneficial in managing hepatic encephalopathy.

Rare NRPS Gene Cluster for Desferriferrichrome Biosynthesis Controls the Conflict between Trap Formation and Nematicidal Activity in Arthrobotrys oligospora.

The formation of the trapping device induced by nematodes has been assumed as an indicator for a switch from saprophytic to predacious lifestyles for nematode-trapping fungi. However, fungal nematocidal activity is not completely synonymous with fungal trap formation. We found that the predominant nematode-trapping fungus Arthrobotrys oligospora harbored a rare NRPS (Ao415) gene cluster that was mainly distributed in nematode-trapping fungi. The gene Ao415 putatively encodes a protein with a unique domain organization, distinct from other NRPSs in other fungi. Mutation of the two key biosynthetic genes Ao415 and Ao414 combined with nontarget metabolic analysis revealed that the Ao415 gene cluster was responsible for the biosynthesis of a hydroxamate siderophore, desferriferrichrome (1). Lack of desferriferrichrome (1) and its hydroxamate precursor (3) could lead to significantly increased Fe3+ content, which induced fungal trap formation without a nematode inducer. Furthermore, the addition of Fe3+ strongly improved fungal trap formation but deleteriously caused broken traps. The addition of 1 significantly attenuated trap formation but enhanced fungal nematicidal activity. Our findings indicate that iron is a key factor for trap formation and provide a new insight into the underlying mechanism of siderophores in nematode-trapping fungi.

Efficacy of L-ornithine L-aspartate for minimal hepatic encephalopathy in patients with cirrhosis: A meta-analysis of randomized controlled trials.

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.

Synthesis of L-Ornithine- and L-Glutamine-Linked PLGAs as Biodegradable Polymers.

L-ornithine and L-glutamine are amino acids used for ammonia and nitrogen transport in the human body. Novel biodegradable synthetic poly(lactic-co-glycolic acid) derivatives were synthesized via conjugation with L-ornithine or L-glutamine, which were selected due to their biological importance. L-ornithine or L-glutamine was integrated into a PLGA polymer with EDC coupling reactions as a structure developer after the synthesis of PLGA via the polycondensation and ring-opening polymerization of lactide and glycolide. The chemical, thermal, and degradation property-structure relationships of PLGA, PLGA-L-ornithine, and PLGA-L-glutamine were identified. The conjugation between PLGA and the amino acid was confirmed through observation of an increase in the number of carbonyl carbons in the range of 170-160 ppm in the 13C NMR spectrum and the signal of the amide carbonyl vibration at about 1698 cm-1 in the FTIR spectrum. The developed PLGA-L-ornithine and PLGA-L-glutamine derivatives were thermally stable and energetic materials. In addition, PLGA-L-ornithine and PLGA-L-glutamine, with their unique hydrophilic properties, had faster degradation times than PLGA in terms of surface-type erosion, which covers their requirements. L-ornithine- and L-glutamine-linked PLGAs are potential candidates for development into biodegradable PLGA-derived biopolymers that can be used as raw materials for biomaterials.

Influence of poly-L-ornithine-bile acid nano hydrogels on cellular bioactivity and potential pharmacological applications.

Aim: Cellular bioactivity and pathophysiological changes associated with chronic disorders are considered pivotal detrimental factors when developing novel formulations for biomedical applications. Methods: This paper investigates the use of bile acids and synthetic polypeptide poly-L-ornithine (PLO) in formulations and their impacts on a variety of cell lines, with a particular focus on their cellular bioactivity. Results: The hepatic cell line was the most negatively affected by the presence of PLO, while the muscle and beta-pancreatic cell lines did not show as profound of a negative impact of PLO on cellular viability. PLO was the least disruptive regarding mitochondrial function for muscle and beta cells. Conclusion: The addition of bile acids generally decreased mitochondrial respiration and altered bioenergetic parameters in all cell lines.

In our study, we made special gels using two kinds of materials and different acids found in bile. We wanted to see how these gels affected different cells like muscles, liver and pancreatic beta cells. The gels we made had good traits needed for injections. Liver cells didn't enjoy the new materials very much. Adding bile acids to the materials changed how the cells acted for all cell types we looked at.

Bipolar Membrane Electrodialysis for Direct Conversion of L-Ornithine Monohydrochloride to L-Ornithine.

In this study, bipolar membrane electrodialysis was proposed to directly convert L-ornithine monohydrochloride to L-ornithine. The stack configuration was optimized in the BP-A (BP, bipolar membrane; A, anion exchange membrane) configuration with the Cl- ion migration through the anion exchange membrane rather than the BP-A-C (C, cation exchange membrane) and the BP-C configurations with the L-ornithine+ ion migration through the cation exchange membrane. Both the conversion ratio and current efficiency follow BP-A > BP-A-C > BP-C, and the energy consumption follows BP-A < BP-A-C < BP-C. Additionally, the voltage drop across the membrane stack (two repeating units) and the feed concentration were optimized as 7.5 V and 0.50 mol/L, respectively, due to the low value of the sum of H+ ions leakage (from the acid compartment to the base compartment) and OH- ions migration (from the base compartment to the acid compartment) through the anion exchange membrane. As a result, high conversion ratio (96.1%), high current efficiency (95.5%) and low energy consumption (0.31 kWh/kg L-ornithine) can be achieved. Therefore, bipolar membrane electrodialysis is an efficient, low energy consumption and environmentally friendly method to directly convert L-ornithine monohydrochloride to L-ornithine.

Investigating Doxorubicin's mechanism of action in cervical cancer: a convergence of transcriptomic and metabolomic perspectives.

Introduction: Cervical cancer remains a significant global health burden, and Doxorubicin is a crucial therapeutic agent against this disease. However, the precise molecular mechanisms responsible for its therapeutic effects are not fully understood. Methods: In this study, we employed a multi-omics approach that combined transcriptomic and metabolomic analyses with cellular and in vivo experiments. The goal was to comprehensively investigate the molecular landscape associated with Doxorubicin treatment in cervical cancer. Results: Our unbiased differential gene expression analysis revealed distinct alterations in gene expression patterns following Doxorubicin treatment. Notably, the ANKRD18B gene exhibited a prominent role in the response to Doxorubicin. Simultaneously, our metabolomic analysis demonstrated significant perturbations in metabolite profiles, with a particular focus on L-Ornithine. The correlation between ANKRD18B gene expression and L-Ornithine levels indicated a tightly controlled gene-metabolite network. These results were further confirmed through rigorous cellular and in vivo experiments, which showed reductions in subcutaneous tumor size and significant changes in ANKRD18B, L-Ornithine, and Doxorubicin concentration. Discussion: The findings of this study underscore the intricate interplay between transcriptomic and metabolomic changes in response to Doxorubicin treatment. These insights could have implications for the development of more effective therapeutic strategies for cervical cancer. The identification of ANKRD18B and L-Ornithine as key components in this process lays the groundwork for future research aiming to unravel the complex molecular networks that underlie Doxorubicin's therapeutic mechanism. While this study provides a solid foundation, it also highlights the necessity for further investigation to fully grasp these interactions and their potential implications for cervical cancer treatment.

An orally deliverable ornithine-based self-assembling polymer nanomedicine ameliorates hyperammonemia in acetaminophen-induced acute liver injury.

l-Ornithine (Orn) is a core amino acid responsible for ammonia detoxification in the body via the hepatic urea cycle. Clinical studies in Orn therapy have focused on interventions for hyperammonemia-associated diseases, such as hepatic encephalopathy (HE), a life-threatening neurological symptom affecting more than 80% of patients with liver cirrhosis. However, its low molecular weight (LMW) causes Orn to diffuse nonspecifically and be rapidly eliminated from the body after oral administration, resulting in unfavorable therapeutic efficacy. Hence, Orn is constantly supplied by intravenous infusion in many clinical settings; however, this treatment inevitably decreases patient compliance and limits its application in long-term management. To improve the performance of Orn, we designed self-assembling polyOrn-based nanoparticles for oral administration through ring-opening polymerization of Orn-N-carboxy anhydride initiated with amino-ended poly(ethylene glycol), followed by acylation of free amino groups in the main chain of the polyOrn segment. The obtained amphiphilic block copolymers, poly(ethylene glycol)-block-polyOrn(acyl) (PEG-block-POrn(acyl)), enabled the formation of stable nanoparticles (NanoOrn(acyl)) in aqueous media. We employed the isobutyryl (iBu) group for acyl derivatization in this study (NanoOrn(iBu)). In the healthy mice, daily oral administration of NanoOrn(iBu) for one week did not induce any abnormalities. In the mice exhibiting acetaminophen (APAP)-induced acute liver injury, oral pretreatment with NanoOrn(iBu) effectively reduced systemic ammonia and transaminases levels compared to the LMW Orn and untreated groups. The results suggest that the application of NanoOrn(iBu) is of significant clinical value with the feasibility of oral delivery and improvement in APAP-induced hepatic pathogenesis. STATEMENT OF SIGNIFICANCE: Liver injury is often accompanied by hyperammonemia, a life-threatening condition characterized by elevated blood ammonia levels. Current clinical treatments for reducing ammonia typically entail the invasive approach of intravenous infusion, involving the administration of l-ornithine (Orn) or a combination of Orn and L-aspartate. This method is employed due to the poor pharmacokinetics associated with these compounds. In our pursuit of enhancing therapy, we have developed an orally administrable nanomedicine based on Orn-based self-assembling nanoparticle (NanoOrn(iBu)), which provides sustained Orn supply to the injured liver. Oral administration of NanoOrn(iBu) to healthy mice did not cause any toxic effects. In a mouse model of acetaminophen-induced acute liver injury, oral administration of NanoOrn(iBu) surpassed Orn in reducing systemic ammonia levels and liver damage, thereby establishing NanoOrn(iBu) as a safe and effective therapeutic option.

Current vision on diagnosis and comprehensive care in hepatic encephalopathy.

The first clinical guidelines on hepatic encephalopathy were published in 2009. Almost 14 years since that first publication, numerous advances in the field of diagnosis, treatment, and special condition care have been made. Therefore, as an initiative of the Asociación Mexicana de Gastroenterología A.C., we present a current view of those aspects. The manuscript described herein was formulated by 24 experts that participated in six working groups, analyzing, discussing, and summarizing the following topics: Definition of hepatic encephalopathy; recommended classifications; epidemiologic panorama, worldwide and in Mexico; diagnostic tools; conditions that merit a differential diagnosis; treatment; and primary and secondary prophylaxis. Likewise, these guidelines emphasize the management of certain special conditions, such as hepatic encephalopathy in acute liver failure and acute-on-chronic liver failure, as well as specific care in patients with hepatic encephalopathy, such as the use of medications and types of sedation, describing those that are permitted or recommended, and those that are not.

Poly(l-Ornithine)-Based Polymeric Micelles as pH-Responsive Macromolecular Anticancer Agents.

Anticancer peptides and polymers represent an emerging field of tumor treatment and can physically interact with tumor cells to address the problem of multidrug resistance. In the present study, poly(l-ornithine)-b-poly(l-phenylalanine) (PLO-b-PLF) block copolypeptides were prepared and evaluated as macromolecular anticancer agents. Amphiphilic PLO-b-PLF self-assembles into nanosized polymeric micelles in aqueous solution. Cationic PLO-b-PLF micelles interact steadily with the negatively charged surfaces of cancer cells via electrostatic interactions and kill the cancer cells via membrane lysis. To alleviate the cytotoxicity of PLO-b-PLF, 1,2-dicarboxylic-cyclohexene anhydride (DCA) was anchored to the side chains of PLO via an acid-labile ß-amide bond to fabricate PLO(DCA)-b-PLF. Anionic PLO(DCA)-b-PLF showed negligible hemolysis and cytotoxicity under neutral physiological conditions but recovered cytotoxicity (anticancer activity) upon charge reversal in the weakly acidic microenvironment of the tumor. PLO-based polypeptides might have potential applications in the emerging field of drug-free tumor treatment.

Central Interaction Between L-Ornithine and Neuropeptide Y in the Regulation of Feeding Behavior of Neonatal Chicks.

Ornithine has been identified as a potential satiety signal in the brains of neonatal chicks. We hypothesized that brain nutrient signals such as amino acids and appetite-related neuropeptides synergistically regulate food intake. To test this hypothesis, we investigated the interaction between neuropeptide Y (NPY) and ornithine in the control of feeding behavior in chicks and the associated central and peripheral amino acid metabolic processes. Five-day-old chicks were intracerebroventricularly injected with saline, NPY (375 pmol), or NPY plus ornithine (2 or 4 µmol) at 10 µl per chick, and then subjected to ad libitum feeding conditions; food intake was monitored for 30 min after injection. Brain and plasma samples were collected after the experiment to determine free amino acid concentrations. Co-injection of NPY and ornithine significantly attenuated the orexigenic effect induced by NPY in a dose-dependent manner. Central NPY significantly decreased amino adipic acid, asparagine, γ-aminobutyric acid, leucine, phenylalanine, tyrosine, and isoleucine levels, but significantly increased lysine levels in the brain. Co-injection of NPY and ornithine significantly increased ornithine and proline levels in all examined brain regions, but decreased diencephalic tryptophan and glycine levels compared with those of the control and NPY-alone groups. Co-injection of NPY and high-dose ornithine significantly decreased methionine levels in all brain regions. Central NPY significantly suppressed the plasma concentrations of amino acids, including proline, asparagine, methionine, phenylalanine, tyrosine, leucine, isoleucine, glycine, glutamine, alanine, arginine, and valine, and this reduction was greater when NPY was co-injected with ornithine. These results suggest that brain ornithine interacts with NPY to regulate food intake in neonatal chicks. Furthermore, central NPY may induce an anabolic effect that is modified by co-injection with ornithine.

Subcortical White Matter Stroke in the Mouse: Inducing Injury and Tracking Cellular Proliferation.

Here, we describe a method for inducing subcortical white matter stroke in mice, as well as tracking cellular proliferation through drinking water administration of EdU and ex vivo labeling.

Crystal structure analysis and molecular dynamics simulations of arginase from Thermus thermophilus.

Arginase is a manganese-dependent metalloenzyme that catalyzes the hydrolysis of L-arginine to L-ornithine and urea. The product L-ornithine is an important component which has wide applications in the healthcare and pharmaceutical industry. Enzymatic biosynthesis of L-ornithine is one of the effective methods in which arginase is used as a bio-catalyst. Here, we report the crystal structure of arginase from Thermus thermophilus (TtArginase) in three different crystal forms. All structures were solved by molecular replacement and refined at 2.0 Å, 2.3 Å and 2.91 Å resolution respectively. TtArginase is compared with other structural homologs and the putative catalytic site residues were identified. To understand the thermophilic nature of TtArginase, the sequence and structural factors of TtArginase was compared with its mesophilic counterpart Bacillus subtilis arginase (BsArginase). To get insights on structural stability, molecular dynamics (MD) simulations were carried for TtArginase and BsArginase at three different temperatures (300 K, 333 K and 353 K). The results indicate that TtArginase is comparatively more stable than BsArginase. MD simulations were carried out in the absence of the metal ions at the active site which revealed high plasticity of the active site. The results suggest that metal ions are critical not only for the catalytic function, but also required for the maintenance of the proper active site geometry. Since arginase can be employed for large-scale industrial production of L-ornithine, the structural details of thermophilic arginases such as TtArginase will be helpful to engineer the protein to optimize its enzymatic action in a variety of conditions.Communicated by Ramaswamy H. Sarma.

Poly-L-ornithine blocks the inhibitory effects of fibronectin on oligodendrocyte differentiation and promotes myelin repair.

The extracellular matrix surrounding oligodendrocytes plays an important role during myelination and remyelination in the brain. In many cases, the microenvironment surrounding demyelination lesions contains inhibitory molecules, which lead to repair failure. Accordingly, blocking the activity of these inhibitory factors in the extracellular matrix should lead to more successful remyelination. In the central nervous system, oligodendrocytes form the myelin sheath. We performed primary cell culture and found that a natural increase in fibronectin promoted the proliferation of oligodendrocyte progenitors during the initial stage of remyelination while inhibiting oligodendrocyte differentiation. Poly-L-ornithine blocked these inhibitory effects without compromising fibronectin's pro-proliferation function. Experiments showed that poly-L-ornithine activated the Erk1/2 signaling pathway that is necessary in the early stages of differentiation, as well as PI3K signaling pathways that are needed in the mid-late stages. When poly-L-ornithine was tested in a lysolecithin-induced animal model of focal demyelination, it enhanced myelin regeneration and promoted motor function recovery. These findings suggest that poly-L-ornithine has the potential to be a treatment option for clinical myelin sheath injury.

Impact of L-ornithine L-aspartate on non-alcoholic steatohepatitis-associated hyperammonemia and muscle alterations.

Background: Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common chronic liver disease in the world. Progression toward non-alcoholic steatohepatitis (NASH) is associated with alterations of skeletal muscle. One plausible mechanism for altered muscle compartment in liver disease is changes in ammonia metabolism. In the present study, we explored the hypothesis that NASH-associated hyperammonemia drives muscle changes as well as liver disease progression. Materials and methods: In Alms1-mutant mice (foz/foz) fed a 60% fat diet (HFD) for 12 weeks; we investigated hepatic and muscular ammonia detoxification efficiency. We then tested the effect of an 8 week-long supplementation with L-ornithine L-aspartate (LOLA), a known ammonia-lowering treatment, given after either 4 or 12 weeks of HFD for a preventive or a curative intervention, respectively. We monitored body composition, liver and muscle state by micro computed tomography (micro-CT) as well as muscle strength by four-limb grip test. Results: According to previous studies, 12 weeks of HFD induced NASH in all foz/foz mice. Increase of hepatic ammonia production and alterations of urea cycle efficiency were observed, leading to hyperammonemia. Concomitantly mice developed marked myosteatosis. First signs of myopenia occurred after 20 weeks of diet. Early LOLA treatment given during NASH development, but not its administration in a curative regimen, efficiently prevented myosteatosis and muscle quality, but barely impacted liver disease or, surprisingly, ammonia detoxification. Conclusion: Our study confirms the perturbation of hepatic ammonia detoxification pathways in NASH. Results from the interventional experiments suggest a direct beneficial impact of LOLA on skeletal muscle during NASH development, though it does not improve ammonia metabolism or liver disease.

Supplementation of L-Ornithine Could Increase Sleep-like Behavior in the Mouse Pups.

Along the maternal-fetal-neonatal axis, one of the problems relating to the maternal-neonatal axis is infant sleep problems including nighttime crying. One possible solution could be to provide the newborn with sleep-promoting ingredients through breast milk or formula. So far, it has been reported that L-ornithine has a sleep-related effect. Therefore, we investigated the effect of dietary L-ornithine on maternal mouse plasma and milk L-ornithine levels in Experiment 1. In Experiment 2, a single dose of L-ornithine was applied to know the time-course changes in plasma, mammary gland and milk L-ornithine levels. Experiment 3 was conducted to confirm sleep behavior as well as changes in polyamine levels in milk. L-Ornithine levels in maternal plasma significantly increased by both dietary regimen and single oral administration in Experiments 1 and 2. Both L-ornithine treatments also increased its levels in milk, although not to a concentration as high as in plasma. In Experiment 3, the level of polyamines, which are metabolized from L-ornithine, did not significantly differ after L-ornithine administration. In sleep-like behavior observations, the average concentration of L-ornithine in milk did not increase the sleep-like behavior of mouse pups. However, more concentrated L-ornithine solutions can significantly increase sleep-like behavior. These results revealed that even if mothers ingested L-ornithine to increase L-ornithine levels in breast milk, it is difficult to promote sleep in newborns. Because it is difficult to raise L-ornithine in breast milk to sleep-inducing levels, L-ornithine added formula may partially improve infant sleep and has the potential for preventing infant sleep problems such as nighttime crying.