Metabolic disorders of purine metabolism affecting the nervous system

Blood metabolomic and postpartum depression: a mendelian randomization study

BACKGROUND

Postpartum depression is a complex mental health condition that often occurs after childbirth and is characterized by persistent sadness, anxiety, and fatigue. Recent research suggests a metabolic component to the disorder. This study aims to investigate the causal relationship between blood metabolites and postpartum depression using mendelian randomization (MR).

METHODS

This study used a bi-directional MR framework to investigate the causal relationship between 1,400 metabolic biomarkers and postpartum depression. We used two specific genome-wide association studies datasets: one with single nucleotide polymorphisms data from mothers diagnosed with postpartum depression and another with blood metabolite data, both of which focused on people of European ancestry. Genetic variants were chosen as instrumental variables from both datasets using strict criteria to improve the robustness of the MR analysis. The combination of these datasets enabled a thorough examination of genetic influences on metabolic profiles associated with postpartum depression. Statistical analyses were conducted using techniques such as inverse variance weighting, weighted median, and model-based estimation, which enabled rigorous causal inference from the observed associations. postpartum depression was defined using endpoint definitions approved by the FinnGen study's clinical expert groups, which included leading experts in their respective medical fields.

RESULTS

The MR analysis identified seven metabolites that could be linked to postpartum depression. Out of these, one metabolite was found to be protective, while six were associated with an increased risk of developing the condition. The results were consistent across multiple MR methods, indicating a significant correlation.

CONCLUSIONS

This study emphasizes the potential of metabolomics for understanding postpartum depression. The discovery of specific metabolites associated with the condition sheds new insights on its pathophysiology and opens up possibilities for future research into targeted treatment strategies.

Review of childhood genetic nephrolithiasis and nephrocalcinosis

Nephrolithiasis (NL) is a common condition worldwide. The incidence of NL and nephrocalcinosis (NC) has been increasing, along with their associated morbidity and economic burden. The etiology of NL and NC is multifactorial and includes both environmental components and genetic components, with multiple studies showing high heritability. Causative gene variants have been detected in up to 32% of children with NL and NC. Children with NL and NC are genotypically heterogenous, but often phenotypically relatively homogenous, and there are subsequently little data on the predictors of genetic childhood NL and NC. Most genetic diseases associated with NL and NC are secondary to hypercalciuria, including those secondary to hypercalcemia, renal phosphate wasting, renal magnesium wasting, distal renal tubular acidosis (RTA), proximal tubulopathies, mixed or variable tubulopathies, Bartter syndrome, hyperaldosteronism and pseudohyperaldosteronism, and hyperparathyroidism and hypoparathyroidism. The remaining minority of genetic diseases associated with NL and NC are secondary to hyperoxaluria, cystinuria, hyperuricosuria, xanthinuria, other metabolic disorders, and multifactorial etiologies. Genome-wide association studies (GWAS) in adults have identified multiple polygenic traits associated with NL and NC, often involving genes that are involved in calcium, phosphorus, magnesium, and vitamin D homeostasis. Compared to adults, there is a relative paucity of studies in children with NL and NC. This review aims to focus on the genetic component of NL and NC in children.

Nanomaterials based sensors for analysis of food safety

The freshnessof the food is a major issue because spoiled food lacks critical nutrients for growth and could be harmful to human health if consumed directly. Nanomaterials are captivating due to their unique properties like large surface area, high selectivity, small dimension, great biocompatibility and conductivity, real-time onsite analysis, etc. which give them an advantage over conventional evaluation techniques. Despite these advantages of nanomaterials used in food safety and their preservation, food products can still get affected by various environmental factors (like pH, temperature, etc.), making the use of time-temperature indicators more condescending. This review is a comprehensive study on food safety, its causes, the responsible analytes, their remedies by various nanomaterials, the development of various nanosensors, and the various challenges faced in maintaining food safety standards to reduce the risk of contaminants.

Systems-level analyses dissociate genetic regulators of reactive oxygen species and energy production

Respiratory chain dysfunction can decrease ATP and increase reactive oxygen species (ROS) levels. Despite the importance of these metabolic parameters to a wide range of cellular functions and disease, we lack an integrated understanding of how they are differentially regulated. To address this question, we adapted a CRISPRi- and FACS-based platform to compare the effects of respiratory gene knockdown on ROS to their effects on ATP. Focusing on genes whose knockdown is known to decrease mitochondria-derived ATP, we showed that knockdown of genes in specific respiratory chain complexes (I, III, and CoQ10 biosynthesis) increased ROS, whereas knockdown of other low ATP hits either had no impact (mitochondrial ribosomal proteins) or actually decreased ROS (complex IV). Moreover, although shifting metabolic conditions profoundly altered mitochondria-derived ATP levels, it had little impact on mitochondrial or cytosolic ROS. In addition, knockdown of a subset of complex I subunits-including NDUFA8, NDUFB4, and NDUFS8-decreased complex I activity, mitochondria-derived ATP, and supercomplex level, but knockdown of these genes had differential effects on ROS. Conversely, we found an essential role for ether lipids in the dynamic regulation of mitochondrial ROS levels independent of ATP. Thus, our results identify specific metabolic regulators of cellular ATP and ROS balance that may help dissect the roles of these processes in disease and identify therapeutic strategies to independently target energy failure and oxidative stress.

Polymorphisms and expressions of ADSL, MC4R and CAPN1 genes and their effects on economic traits in Egyptian chicken breeds

In recent years, strategic plans for poultry production have emphasized quantitative traits, particularly body weight and carcass traits (meat yield), in response to overpopulation challenges. Candidate genes such as adenylosuccinate lyase (ADSL), melanocortin-4-receptor (MC4R), and calpain 1 (CAPN1) have played vital roles in this context due to their associations with muscle growth and body composition. This study aims to investigate the influence of polymorphisms and gene expressions of the aforementioned genes on body weight (BW), growth rate (GR), breast weight (BrW), and thigh weight (TW) across four distinct chicken breeds: Fayoumi, Matrouh, Mamourah, and Leghorn. The use of PCR-SSCP analysis revealed genetic polymorphisms through the identification of various patterns (genotypes) within the three examined genes. The ADSL, MC4R, and CAPN1 genes exhibited five, three, and two different genotypes, respectively. These polymorphisms displayed promising connections with enhancing economically significant production traits, particularly BW, BrW and TW. Furthermore, gene expression analyses were conducted on breast and thigh tissues obtained from the chicken breeds at 60 days of age, where ADSL and MC4R exhibited a noteworthy up-regulation in Fayoumi and Matrouh breeds, and down-regulation in Mamourah and Leghorn. In contrast, CAPN1 expression decreased across most breeds with a slight increase noted in Fayoumi breed. In conclusion, this investigation underscores the substantial impact of ADSL, MC4R, and CAPN1 genes on economically important production traits within Egyptian domestic chicken breeds. Consequently, these genes emerge as significant molecular markers, holding potential utility in avian selection and breeding programs aimed at enhancing productive performance.

Cochlear metabolomics, highlighting novel insights of purine metabolic alterations in age-related hearing loss

Aging is an inevitable phase in mammals that leads to health impairments, including hearing loss. Age-related hearing loss (AHL) leads to psychosocial problems and cognitive decline in the elderly. In this study, mean thresholds of auditory brainstem responses (ABR) and distortion-product otoacoustic emissions (DPOAE) increased at multiple frequencies in aged rats (14 months old) compared to young rats (2 months old). Using untargeted ultra-high performance liquid chromatography-mass spectroscopy (LC-MS), we quantified molecular metabolic markers in the cochlea of aged rats with hearing loss. A total of 137 different metabolites were identified in two groups, highlighting several prominent metabolic pathways related to purine metabolism; glycine, serine, and threonine metabolism; arginine and proline metabolism; and pyrimidine metabolism. In addition, the beneficial effects of purine supplementation were demonstrated in a mimetic model of senescent marginal cells (MCs). Overall, altered metabolic profiling is both the cause and manifestation of pathology, and our results suggest that cellular senescence and dysfunctional cochlear metabolism may contribute to the progression of AHL. These findings are seminal in elucidating the pathophysiological mechanisms underlying AHL and serve as a basis for future clinical predictions and interventions in AHL.

Systems-level analyses dissociate genetic regulators of reactive oxygen species and energy production

Respiratory chain dysfunction can decrease ATP and increase reactive oxygen species (ROS) levels. Despite the importance of these metabolic parameters to a wide range of cellular functions and disease, we lack an integrated understanding of how they are differentially regulated. To address this question, we adapted a CRISPRi- and FACS- based platform to compare the effects of respiratory gene knockdown on ROS to their effects on ATP. Focusing on genes whose knockdown is known to decrease mitochondria-derived ATP, we showed that knockdown of genes in specific respiratory chain complexes (I, III and CoQ10 biosynthesis) increased ROS, whereas knockdown of other low ATP hits either had no impact (mitochondrial ribosomal proteins) or actually decreased ROS (complex IV). Moreover, although shifting metabolic conditions profoundly altered mitochondria-derived ATP levels, it had little impact on mitochondrial or cytosolic ROS. In addition, knockdown of a subset of complex I subunits-including NDUFA8, NDUFB4, and NDUFS8-decreased complex I activity, mitochondria-derived ATP and supercomplex level, but knockdown of these genes had differential effects on ROS. Conversely, we found an essential role for ether lipids in the dynamic regulation of mitochondrial ROS levels independent of ATP. Thus, our results identify specific metabolic regulators of cellular ATP and ROS balance that may help dissect the roles of these processes in disease and identify therapeutic strategies to independently target energy failure and oxidative stress.

Comparative study and relationship analysis between purine content, uric acid, superoxide dismutase, and growth traits in purebred and crossbred Thai native chickens

The objective was to compare and analyze the relationship between growth, purine content, uric acid, and superoxide dismutase (SOD) in purebred and crossbred Thai native chickens. A total of 300 Thai native chickens were divided into 3 groups. Group 1 was purebred Thai native chickens (100%TN), Group 2 was 50% Thai native chickens (50%TN), and Group 3 was 25% Thai native chickens (25%TN). Data included the body weight (BW), average daily gain (ADG), and breast circumference (BrC). At 6, 8, and 10 weeks of age, 10 chickens from each group were randomly euthanized to collect breast meat, liver, and blood samples to analyze the purine content consisting of total purine, adenine, guanine, xanthine, and hypoxanthine, and uric acid, in breast meat and liver and SOD in blood. A general linear model, Pearson correlation and principal component analysis were used to analyze the significant differences and relationship between variables. The results showed the 25%TN group had the highest growth traits at every age, while the 100%TN group had the lowest (p < 0.05). Consistent with the analysis results of purine values, purine content and uric acid in breast meat and liver and SOD in blood decreased with age (p < 0.05). The correlations between purine content (total purine, adenine, guanine, xanthine, and hypoxanthine) and growth traits (BW, ADG, and BrC) ranged from moderate negative to moderate positive (-0.542 to 0.253)(p < 0.05). The correlations between uric acid and growth traits (0.348-0.760) and SOD and growth traits (0.132-0.516) were low to moderate positive with significant differences (p < 0.05). The principal component plot, which highlighted three principal components (PC 1, PC 2, and PC 3), explained 86.44 and 86.53% of the total information in breast meat and liver for selecting animals for optimal balance of the variation in the growth traits, purine content, uric acid, and SOD. Although purebred Thai native chickens showed the lowest growth traits, purine content, uric acid, and SOD were also lowest compared to crossbred Thai native chickens. Therefore, the development of genetics in Thai native chickens to produce healthy food could be possible.

Adenylosuccinate lyase deficiency affects neurobehavior via perturbations to tyramine signaling in Caenorhabditis elegans

Adenylosuccinate lyase deficiency is an ultrarare congenital metabolic disorder associated with muscle weakness and neurobehavioral dysfunction. Adenylosuccinate lyase is required for de novo purine biosynthesis, acting twice in the pathway at non-sequential steps. Genetic models can contribute to our understanding of the etiology of disease phenotypes and pave the way for development of therapeutic treatments. Here, we establish the first model to specifically study neurobehavioral aspects of adenylosuccinate lyase deficiency. We show that reduction of adsl-1 function in C. elegans is associated with a novel learning phenotype in a gustatory plasticity assay. The animals maintain capacity for gustatory plasticity, evidenced by a change in their behavior in response to cue pairing. However, their behavioral output is distinct from that of control animals. We link substrate accumulation that occurs upon adsl-1 deficiency to an unexpected perturbation in tyrosine metabolism and show that a lack of tyramine mediates the behavioral changes through action on the metabotropic TYRA-2 tyramine receptor. Our studies reveal a potential for wider metabolic perturbations, beyond biosynthesis of purines, to impact behavior under conditions of adenylosuccinate lyase deficiency.

Dystonia genes and their biological pathways

High-throughput sequencing has been instrumental in uncovering the spectrum of pathogenic genetic alterations that contribute to the etiology of dystonia. Despite the immense heterogeneity in monogenic causes, studies performed during the past few years have highlighted that many rare deleterious variants associated with dystonic presentations affect genes that have roles in certain conserved pathways in neural physiology. These various gene mutations that appear to converge towards the disruption of interconnected cellular networks were shown to produce a wide range of different dystonic disease phenotypes, including isolated and combined dystonias as well as numerous clinically complex, often neurodevelopmental disorder-related conditions that can manifest with dystonic features in the context of multisystem disturbances. In this chapter, we summarize the manifold dystonia-gene relationships based on their association with a discrete number of unifying pathophysiological mechanisms and molecular cascade abnormalities. The themes on which we focus comprise dopamine signaling, heavy metal accumulation and calcifications in the brain, nuclear envelope function and stress response, gene transcription control, energy homeostasis, lysosomal trafficking, calcium and ion channel-mediated signaling, synaptic transmission beyond dopamine pathways, extra- and intracellular structural organization, and protein synthesis and degradation. Enhancing knowledge about the concept of shared etiological pathways in the pathogenesis of dystonia will motivate clinicians and researchers to find more efficacious treatments that allow to reverse pathologies in patient-specific core molecular networks and connected multipathway loops.

Title: Obesogenic microbial signatures and the development of obesity in childhood acute lymphoblastic leukemia

Childhood acute lymphoblastic leukemia (ALL) is the most common childhood cancer with survival exceeding 90% for standard-risk groups. A debilitating side-effect of treatment is the development of overweight/obesity (OW/OB), which develops in approximately 40% of children by the end of treatment. The microbiome has been associated with the development of OW/OB. We examined fluctuations in the microbiome with the development of OW/OB during the first six months of treatment at diagnosis, and two subsequent timepoints (N = 62). Shotgun metagenomic sequencing was performed on Illumina Nextseq system, and taxa and functional pathways were extracted from sequences using kraken2 and humann2, respectively. An association of increased presence of several species (e.g., Klebsiella pneumoniae, Escherichia coli) was observed in children with OW/OB, while lean-promoting species (Veillonella, Haemophilus, and Akkermansia) were increased in children who maintained a normal weight. Pathway analysis revealed purine nucleotide biosynthesis, sugar nucleotide biosynthesis, and enzyme cofactor biosynthesis were positively correlated with Bacteroides spp. among children with OW/OB. We identified several taxa and functional pathways that may confer increased risk for the development of OW/OB. The associations observed in this pilot are preliminary and warrant further research in the microbiome and the development of OW/OB in childhood ALL.

Integrative Multiomics Analysis of the Heat Stress Response of Enterococcus faecium

A continuous heat-adaptation test was conducted for one Enterococcus faecium (E. faecium) strain wild-type (WT) RS047 to obtain a high-temperature-resistant strain. After domestication, the strain was screened with a significantly higher ability of heat resistance. which is named RS047-wl. Then a multi-omics analysis of transcriptomics and metabolomics was used to analyze the mechanism of the heat resistance of the mutant. A total of 98 differentially expressed genes (DEGs) and 115 differential metabolites covering multiple metabolic processes were detected in the mutant, which indicated that the tolerance of heat resistance was regulated by multiple mechanisms. The changes in AgrB, AgrC, and AgrA gene expressions were involved in quorum-sensing (QS) system pathways, which regulate biofilm formation. Second, highly soluble osmotic substances such as putrescine, spermidine, glycine betaine (GB), and trehalose-6P were accumulated for the membrane transport system. Third, organic acids metabolism and purine metabolism were down-regulated. The findings can provide target genes for subsequent genetic modification of E. faecium, and provide indications for screening heat-resistant bacteria, so as to improve the heat-resistant ability of E. faecium for production.

The mammalian purine salvage pathway as an exploitable route for cerebral bioenergetic support after brain injury

Purine-based molecules play ancient, fundamental, and evolutionarily-conserved roles across life on Earth, ranging from DNA and RNA, to the universal energy currency, ATP. In mammals, the two primary routes for the synthesis of the adenine nucleotides ATP, ADP and AMP, and, as a consequence, the major bioactive metabolite adenosine, are the de novo purine biosynthesis (DNPB) pathway, and the purine salvage pathway (PSP). Of the two, the PSP dominates in both the mammalian brain and heart. This is because the PSP utilizes the breakdown products of ATP, occasioned by the high energy demands of these organs, to rapidly regenerate adenine nucleotides. This resynthesis route, while efficient and energetically favourable, leaves these organs vulnerable to loss of salvageable metabolites, with the potential for protracted depletion of the means to synthesize ATP, and the ability to deploy neuro- and cardioprotective adenosine. Having previously shown that hippocampal cellular ATP and adenosine release can be increased by supplying substrates for the PSP (d-ribose and adenine), we now explore the expression of DNPB and PSP enzymes in hippocampal neurons and astrocytes based on available transcriptomic data. We find that key enzymes of the PSP are expressed at higher levels than those in the DNPB pathway, and that PSP enzymes are expressed at higher levels in neurons than in astrocytes. These data reflect the importance of the PSP in the mammalian brain and imply that pharmacological targeting of the PSP may be particularly beneficial to neurons at times of metabolic stress. This article is part of the Special Issue on 'Purinergic Signaling: 50 years'.

Disorders of Hippocampus Facilitated by Hypertension in Purine Metabolism Deficiency is Repressed by Naringin, a Bi-flavonoid in a Rat Model via NOS/cAMP/PKA and DARPP-32, BDNF/TrkB Pathways

Individuals who are hypertensive have a higher tendency of predisposition to other genetic diseases including purine metabolism deficiency. Therefore, the search for nontoxic and effective chemo protective agents to abrogate hypertension-mediated genetic disease is vital. This study therefore investigated the repressive effect of naringin (NAR) against disorder of hippocampus facilitated by hypertension in purine metabolism deficiency. Male albino rats randomly assigned into nine groups (n = 7) were treated for 35 days. Group I: control animals, Group II was treated with 100 mg/kg KBrO₃, Group III was treated with 250 mg/kg caffeine, and Group IV was treated with 100 mg/kg KBrO₃ + 250 mg/kg caffeine. Group V was administered with 100 mg/kg KBrO₃ + 100 mg/kg haloperidol. Group VI was administered with 100 mg/kg KBrO₃ + 50 mg/kg NAR. Group VII was administered with 250 mg/kg caffeine + 50 mg/kg NAR, and Group VIII was administered with 100 mg/kg KBrO₃ + 250 mg/kg caffeine + 50 mg/kg NAR. Finally, group IX was treated with 50 mg/kg NAR. The sub-acute exposure to KBrO₃ and CAF induced hypertension and mediated impairment in the hippocampus cells. This was apparent by the increase in PDE-5¹, arginase, and enzymes of ATP hydrolysis (ATPase and AMPase) with a simultaneous increase in cholinergic (AChE and BuChE) and adenosinergic (ADA) enzymes. The hypertensive-mediated hippocampal impairment was associated to alteration of NO and AC signaling coupled with lower expression of brain-derived neurotrophic factor and its receptor (BDNF-TrkB), down regulation of Bcl11b and DARPP-32 which are neurodevelopmental proteins, and hypoxanthine accumulation. However, these features of CAF-mediated hippocampal damage in KBrO₃-induced hypertensive rats were repressed by post-treatment with NAR via production of neuro-inflammatory mediators, attenuation of biochemical alterations, stabilizing neurotransmitter enzymes, regulating NOS/cAMP/PKA and DARPP-32, BDNF/TrkB signaling, and restoring hippocampal tissues.

Child with adenylosuccinate lyase deficiency caused by a novel complex heterozygous mutation in the ADSL gene: A case report

BACKGROUND

Adenylosuccinate lyase (ADSL) deficiency is a rare autosomal-recessive defect of purine metabolism caused by mutation of the ADSL gene. It can cause severe neurological impairment and diverse clinical manifestations, including epilepsy.

CASE SUMMARY

Here, we describe a 3-year-old Chinese boy who had both psychomotor retardation and refractory epilepsy. Magnetic resonance imaging showed myelin hypoplasia. Electroencephalography findings supported a diagnosis of epilepsy. Whole-exon sequencing revealed the presence of a novel complex heterozygous mutation in the ADSL gene: The splicing mutation c.154-3C>G and the missense mutation c.71C>T (p. Pro24Leu). Considering the patient’s clinical presentation and genetic test results, the complex heterozygous mutation was predicted to prevent both ADSL alleles from producing normal ADSL, which may have led to ADSL deficiency. Finally, the child was diagnosed with ADSL deficiency.

CONCLUSION

We identified a novel complex heterozygous mutation in the ADSL gene associated with ADSL deficiency, thus expanding the known spectrum of pathogenic mutations that cause ADSL deficiency. Additionally, we describe epilepsy that occurs in patients with ADSL deficiency.

Ten Years Milestones in Xanthine Oxidase Inhibitors Discovery: Febuxostat-Based Inhibitors Trends, Bifunctional Derivatives, and Automatized Screening Assays

Xanthine oxidase (XO) is an enzyme involved in the oxidative process of hypoxanthine and xanthine to uric acid (UA). This process also produces reactive oxygen species (ROS) as byproducts. Both UA and ROS are dangerous for human health, and some health conditions trigger upregulation of XO activity, which results in many diseases (cancer, atherosclerosis, hepatitis, gout, and others) given the worsened scenario of ROS and UA overproduction. So, XO became an attractive target to produce and discover novel selective drugs based on febuxostat, the most recent XO inhibitor out of only two approved by FDA. Under this context, high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) have been successfully applied to rapidly and easily screen for bioactive compounds, isolated or in complex natural matrixes, that act as enzyme inhibitors through the use of an immobilized enzyme reactor (IMER). This article’s goal is to present advances comprising febuxostat-based XO inhibitors as a new trend, bifunctional moieties capable of inhibiting XO and modulating ROS activity, and in-flow techniques employing an IMER in HPLC and CE to screen for synthetic and natural compounds that act as XO inhibitors.

Metabolomics Reveal Nanoplastic-Induced Mitochondrial Damage in Human Liver and Lung Cells

Plastic debris in the global biosphere is an increasing concern, and nanoplastic (NPs) toxicity in humans is far from being understood. Studies have indicated that NPs can affect mitochondria, but the underlying mechanisms remain unclear. The liver and lungs have important metabolic functions and are vulnerable to NP exposure. In this study, we investigated the effects of 80 nm NPs on mitochondrial functions and metabolic pathways in normal human hepatic (L02) cells and lung (BEAS-2B) cells. NP exposure did not induce mass cell death; however, transmission electron microscopy analysis showed that the NPs could enter the cells and cause mitochondrial damage, as evidenced by overproduction of mitochondrial reactive oxygen species, alterations in the mitochondrial membrane potential, and suppression of mitochondrial respiration. These alterations were observed at NP concentrations as low as 0.0125 mg/mL, which might be comparable to the environmental levels. Nontarget metabolomics confirmed that the most significantly impacted processes were mitochondrial-related. The metabolic function of L02 cells was more vulnerable to NP exposure than that of BEAS-2B cells, especially at low NP concentrations. This study identifies NP-induced mitochondrial dysfunction and metabolic toxicity pathways in target human cells, providing insight into the possibility of adverse outcomes in human health.

De Novo Purine Nucleotide Biosynthesis Pathway Is Required for Development and Pathogenicity in Magnaporthe oryzae

Purine nucleotides are indispensable compounds for many organisms and participate in basic vital activities such as heredity, development, and growth. Blocking of purine nucleotide biosynthesis may inhibit proliferation and development and is commonly used in cancer therapy. However, the function of the purine nucleotide biosynthesis pathway in the pathogenic fungus Magnaporthe oryzae is not clear. In this study, we focused on the de novo purine biosynthesis (DNPB) pathway and characterized MoAde8, a phosphoribosylglycinamide formyltransferase, catalyzing the third step of the DNPB pathway in M. oryzae. MoAde8 was knocked out, and the mutant (∆Moade8) exhibited purine auxotroph, defects in aerial hyphal growth, conidiation, and pathogenicity, and was more sensitive to hyperosmotic stress and oxidative stress. Moreover, ∆Moade8 caused decreased activity of MoTor kinase due to blocked purine nucleotide synthesis. The autophagy level was also impaired in ∆Moade8. Additionally, MoAde5, 7, 6, and 12, which are involved in de novo purine nucleotide biosynthesis, were also analyzed, and the mutants showed defects similar to the defects of ∆Moade8. In summary, de novo purine nucleotide biosynthesis is essential for conidiation, development, and pathogenicity in M. oryzae.

Synergistic neuroprotective effect of saikosaponin A and albiflorin on corticosterone-induced apoptosis in PC12 cells via regulation of metabolic disorders and neuroinflammation

BACKGROUND

Saikosaponin A (SSA) and albiflorin (AF) are major bioactive compounds of Radix Bupleuri and Radix Paeoniae alba respectively, which possess antidepressant effects in pharmacological experiments. However, whether SSA and AF have synergistic neuroprotective effects and the synergistic mechanisms are still unknown.

METHODS AND RESULTS

The corticosterone-induced PC12 cells apoptosis model was employed to assess the neuroprotective effects of SSA and AF, and the synergistic effect was analyzed using three mathematical models. Meanwhile, cell metabolomics was used to detect the effects on metabolite regulation of SSA and AF. Furthermore, the key metabolites, metabolic enzymes, and cellular markers were verified by ELISA and Western blotting. The results showed that the combination of SSA and AF has a synergistic neuroprotective effect. Besides, the combination could regulate more metabolites than a single agent and possessed a stronger adjustment effect on metabolites. The TCA cycle was regulated by SSA and AF via improving mitochondrial function. The purine metabolism was regulated by SSA via inhibition xanthine oxidase activity and the glutamate metabolism was regulated by AF via inhibition glutaminase activity. Moreover, the oxidative stress induced by the purine metabolism was attenuated by SSA via a reduction in the ROS level. Additionally, the inflammation induced by the oxidative stress was attenuated by the SSA and AF via inhibition of the NLRP3 protein expression.

CONCLUSIONS

This study for the first time demonstrated the synergistic neuroprotective effects of SSA and AF, and the synergistic mechanisms were involved in metabolic disorders regulation and neuroinflammation inhibition.

De novo purine nucleotide biosynthesis mediated by MoAde4 is required for conidiation, host colonization and pathogenicity in Magnaporthe oryzae

Amidophosphoribosyltransferase catalyzes the conversion of 5-phosphoribosyl-1-pyrophosphate into 5-phosphoribosyl-1-amine in the de novo purine biosynthetic pathway. Herein, we identified and characterized the functions of MoAde4, an orthologue of yeast Ade4 in Magnaporthe oryzae. MoAde4 is a 537-amino acid protein containing GATase_6 and pribosyltran domains. MoADE4 transcripts were highly expressed during the conidiation, early-infection, and late-infection stages of the fungus. Disruption of the MoADE4 gene resulted in ΔMoade4 exhibiting adenine, adenosine, and hypoxanthine auxotrophy on minimal medium. Conidia quantification assays showed that sporulation was significantly reduced in the ΔMoade4 mutant. The conidia of ΔMoade4 could still form appressoria but mostly failed to penetrate the rice cuticle. Pathogenicity tests showed that ΔMoade4 was completely nonpathogenic on rice and barley leaves, which was attributed to restricted infectious hyphal growth within the primary cells. The ΔMoade4 mutant was defective in the induction of strong host immunity. Exogenous adenine partially rescued conidiation, infectious hyphal growth, and the pathogenicity defects of the ΔMoade4 mutant on barley and rice leaves. Taken together, our results demonstrated that purine nucleotide biosynthesis orchestrated by MoAde4 is required for fungal development and pathogenicity in M. oryzae. These findings therefore act as a suitable target for antifungal development against recalcitrant plant fungal pathogens. KEY POINTS: • MoAde4 is crucial for de novo purine nucleotide biosynthesis. • MoAde4 is pivotal for conidiogenesis and appressorium development of M. oryzae. • MoAde4 is involoved in the pathogenicity of M. oryzae.

Sarcodia suae modulates the immunity and disease resistance of white shrimp Litopenaeus vannamei against Vibrio alginolyticus via the purine metabolism and phenylalanine metabolism

Red seaweeds have several biofunctional properties, including immunomodulatory, antitumor, antioxidant, and antibacterial activities. In this study, we examined the effects of diets containing Sarcodia suae on the immune response, immune-related gene expressions, and disease resistance against Vibrio alginolyticus in white shrimp Litopenaeus vannamei. In addition, ¹H NMR metabolomics was applied to analyze the metabolites extracted from shrimp fed with S. suae and their functions in regulating immunity. A diet containing only fish meal was used as the control diet (S₀), and three diets containing different concentrations of S. suae powder, 2.5% (S2.5), 5% (S5), and 7.5% (S7.5) were used as experimental diets. Shrimp were fed diets for 20 days. Compared to the control group (S0), results showed that (1) shrimp fed diets supplemented with 5-7.5% of S. suae powder significantly increased anti-V. alginolyticus activity; (2) phagocytic activity (PA) increased in all shrimp fed with S. suae, but total haemocyte count (THC) only increased in S7.5 group; and (3) the expression of glutathione peroxidase (GPx) in haemocyte were significantly higher in S7.5 groups. Results from the ¹H NMR analysis revealed that 19 heapatopancreatic metabolites were matched and identified among groups. Based on the KEGG enrichment analysis, the up-regulated metabolites in the shrimp fed S5 and S7.5 diets were primarily due to the metabolism of purine and phenylalanine and their respective pathways. Results from these trials reveal that diets containing S. suae can increase immune response, thereby increasing shrimp resistance to V. alginolyticus. The purine and phenylalanine metabolic pathways may be considered as the relevant pathways for optimizing immunomodulatory responses.

Inborn errors of purine and pyrimidine metabolism: A guide to diagnosis

Inborn errors of purine and pyrimidine (P/P) metabolism are under-reported and rarely mentioned in the general literature or in clinical practice, as well as in reviews dedicated to other inborn errors of metabolism (IEMs). However, their diagnosis is important because genetic counseling can be provided and, in some cases, specific treatment exists that may slow or even reverse clinical signs. The purpose of this review is to provide a practical guideline on the suspicion and investigation of inborn errors of P/P metabolism. Failure of a physician to recognize the presence of these disorders may be devastating for affected infants and children because of its permanent effects in the patient, and for their parents because of implications for future offspring. Diagnosis is crucial because genetic counseling can be provided and, in some cases, specific treatment can be offered that may slow or even reverse clinical symptoms. This review highlights the risk factors in the history, the important examination findings, and the appropriate biochemical investigation of the child. Herein we describe the approach to the diagnosis of P/P disorders and emphasize clinical situations in which physicians should consider these diseases as diagnostic possibilities.

Neurodegeneration and Early Infantile Epilepsy Associated with ITPA Variants: A Case Series and Review of Literature

BACKGROUND

Inosine triphosphate pyrophosphohydrolase (ITPase) deficiency associated with mutations in the ITPA gene is a recently characterized purine pathway defect that presents with early infantile epileptic encephalopathy and lethal course. This disorder is rare, and only 12 cases are reported worldwide.

METHODS

We report two additional cases of ITPA-associated neurodegeneration and two pathogenic compound heterozygous variants. We also reviewed the previously published cases of ITPA-associated encephalopathy.

RESULTS

Both cases presented with progressive infantile-onset encephalopathy, severe developmental delay, microcephaly, facial dysmorphism, and epilepsy. Together with the presented two cases, 14 cases were available for analysis. The mean age of presentation was 16.7 ± 12.4 months (range 3-48 m). The most common clinical features at presentation were developmental delay, seizures, microcephaly, and hypotonia, seen in all 14 (100%) patients. The mean age of seizure onset was 4.75 months (range 2-14 m). Cardiomyopathy was noted in 42% of patients where it was explicitly evaluated (n = 5/12). Consanguinity was reported in 77% of the cases. The cardinal neuroradiological features are T2-signal abnormalities and diffusion restriction in the long tracts, especially the posterior limb of the internal capsule and the optic radiation. The majority of the patients died before 4 years of age (85.7%).

CONCLUSION

ITPA-related encephalopathy presents with infantile-onset neurodegeneration, progressive microcephaly, and epilepsy. Progressive brain atrophy and diffusion restriction in the white matter tracts are important radiological clues.

Hfq Regulates Efflux Pump Expression and Purine Metabolic Pathway to Increase Trimethoprim Resistance in Aeromonas veronii

Aeromonas veronii (A. veronii) is a zoonotic pathogen. It causes clinically a variety of diseases such as dysentery, bacteremia, and meningitis, and brings huge losses to aquaculture. A. veronii has been documented as a multiple antibiotic resistant bacterium. Hfq (host factor for RNA bacteriophage Qβ replication) participates in the regulations of the virulence, adhesion, and nitrogen fixation, effecting on the growth, metabolism synthesis and stress resistance in bacteria. The deletion of hfq gene in A. veronii showed more sensitivity to trimethoprim, accompanying by the upregulations of purine metabolic genes and downregulations of efflux pump genes by transcriptomic data analysis. Coherently, the complementation of efflux pump-related genes acrA and acrB recovered the trimethoprim resistance in Δhfq. Besides, the accumulations of adenosine and guanosine were increased in Δhfq in metabonomic data. The strain Δhfq conferred more sensitive to trimethoprim after appending 1 mM guanosine to M9 medium, while wild type was not altered. These results demonstrated that Hfq mediated trimethoprim resistance by elevating efflux pump expression and degrading adenosine, and guanosine metabolites. Collectively, Hfq is a potential target to tackle trimethoprim resistance in A. veronii infection.

A map of metabolic phenotypes in patients with myalgic encephalomyelitis/chronic fatigue syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disease usually presenting after infection. Emerging evidence supports that energy metabolism is affected in ME/CFS, but a unifying metabolic phenotype has not been firmly established. We performed global metabolomics, lipidomics, and hormone measurements, and we used exploratory data analyses to compare serum from 83 patients with ME/CFS and 35 healthy controls. Some changes were common in the patient group, and these were compatible with effects of elevated energy strain and altered utilization of fatty acids and amino acids as catabolic fuels. In addition, a set of heterogeneous effects reflected specific changes in 3 subsets of patients, and 2 of these expressed characteristic contexts of deregulated energy metabolism. The biological relevance of these metabolic phenotypes (metabotypes) was supported by clinical data and independent blood analyses. In summary, we report a map of common and context-dependent metabolic changes in ME/CFS, and some of them presented possible associations with clinical patient profiles. We suggest that elevated energy strain may result from exertion-triggered tissue hypoxia and lead to systemic metabolic adaptation and compensation. Through various mechanisms, such metabolic dysfunction represents a likely mediator of key symptoms in ME/CFS and possibly a target for supportive intervention.

Transcriptome and metabolome analysis of crGART, a novel cell model of de novo purine synthesis deficiency: Alterations in CD36 expression and activity

In humans, GART [phosphoribosylglycinamide formyltransferase (EC 2.1.2.2) / phosphoribosylglycinamide synthetase (EC 6.3.4.13) / phosphoribosylaminoimidazole synthetase (EC 6.3.3.1)] is a trifunctional protein which catalyzes the second, third, and fifth reactions of the ten step de novo purine synthesis (DNPS) pathway. The second step of DNPS is conversion of phosphoribosylamine (5-PRA) to glycineamide ribonucleotide (GAR). 5-PRA is extremely unstable under physiological conditions and is unlikely to accumulate in the absence of GART activity. Recently, a HeLa cell line null mutant for GART was constructed via CRISPR-Cas9 mutagenesis. This cell line, crGART, is an important cellular model of DNPS inactivation that does not accumulate DNPS pathway intermediates. In the current study, we characterized the crGART versus HeLa transcriptomes in purine-supplemented and purine-depleted growth conditions. We observed multiple transcriptome changes and discuss pathways and ontologies particularly relevant to Alzheimer disease and Down syndrome. We selected the Cluster of Differentiation (CD36) gene for initial analysis based on its elevated expression in crGART versus HeLa as well as its high basal expression, high log2 value, and minimal P-value.

Purine metabolites and complex diseases: role of genes and nutrients

PURPOSE OF REVIEW

Purines have several important physiological functions as part of nucleic acids and as intracellular and extracellular signaling molecules. Purine metabolites, particularly uric acid, have been implicated in congenital and complex diseases. However, their role in complex diseases is not clear and they have both beneficial and detrimental effects on disease pathogenesis. In addition, the relationship between purines and complex diseases is affected by genetic and nutritional factors. This review presents latest findings about the relationship between purines and complex diseases and the effect of genes and nutrients on this relationship.

RECENT FINDINGS

Evidence from recent studies show strong role of purines in complex diseases. Although they are causal in only few diseases, our knowledge about their role in other diseases is still evolving. Of all the purines, uric acid is the most studied. Uric acid acts as an antioxidant as well as a prooxidant under different conditions, thus, its role in disease also varies. Other purines, adenosine and inosine have been less studied, but they have neuroprotective properties which are valuable in neurodegenerative diseases.

SUMMARY

Purines are molecules with great potential in disease pathogenesis as either metabolic markers or therapeutic targets. More studies need to be conducted to understand their relevance for complex diseases.

Metabolomic Profiling of Aqueous Humor and Plasma in Primary Open Angle Glaucoma Patients Points Towards Novel Diagnostic and Therapeutic Strategy

Glaucoma is the second leading cause of blindness globally characterized by progressive loss of retinal ganglion cells (RGCs) and irreversible visual deficiency. As the most common type of glaucoma, primary open angle glaucoma (POAG) is currently an unmet medical need with limited therapy by lowering intraocular pressure (IOP). However, some patients continue to progress even though their IOP are controlled. Although early diagnosis and prompt treatment are crucial in preventing irreversible visual impairment, there are currently no biomarkers for screening POAG. Metabolomics has the advantages of illustrating the final downstream products of the genome and establishing the closest link to the phenotype. So far, there is no study investigating the metabolomic profiles in both aqueous humor and plasma of POAG patients. Therefore, to explore diagnostic biomarkers, unveil underlying pathophysiology and potential therapeutic strategies, a widely targeted metabolomic approach was applied using ultrahigh-resolution mass spectrometry with C18 liquid chromatography to characterize the metabolomic profiles in both aqueous humor and plasma of 28 POAG patients and 25 controls in our study. Partial least squares-discriminant analysis (PLS-DA) was performed to determine differentially expressed metabolites (DEMs) between POAG and age-matched controls. The area under the receiver operating characteristic curve (AUC) was calculated to assess the prediction accuracy of the DEMs. The correlation of DEMs with the clinical parameters was determined by Pearson correlation, and the metabolic pathways were analyzed using MetaboAnalyst 4.0. PLS-DA significantly separated POAG from controls with 22 DEMs in the aqueous humor and 11 DEMs in the plasma. Additionally, univariate ROC analysis and correlation analysis with clinical parameters revealed cyclic AMP (AUC = 0.87), 2-methylbenzoic acid (AUC = 0.75), 3'-sialyllactose (AUC = 0.73) in the aqueous humor and N-lac-phe (AUC = 0.76) in the plasma as potential biomarkers for POAG. Moreover, the metabolic profiles pointed towards the alteration in the purine metabolism pathway. In conclusion, the study identified potential and novel biomarkers for POAG by crosslinking the metabolomic profiles in aqueous humor and plasma and correlating with the clinical parameters. These findings have important clinical implications given that no biomarkers are currently available for glaucoma in the clinic, and the study provided new insights in exploring diagnostic biomarkers and potential therapeutic strategies of POAG by targeting metabolic pathways.

CCL5 promotion of bioenergy metabolism is crucial for hippocampal synapse complex and memory formation

Glucoregulatory efficiency and ATP production are key regulators for neuronal plasticity and memory formation. Besides its chemotactic and neuroinflammatory functions, the CC chemokine--CCL5 displays neurotrophic activity. We found impaired learning-memory and cognition in CCL5-knockout mice at 4 months of age correlated with reduced hippocampal long-term potentiation and impaired synapse structure. Re-expressing CCL5 in knockout mouse hippocampus restored synaptic protein expression, neuronal connectivity and cognitive function. Using metabolomics coupled with FDG-PET imaging and seahorse analysis, we found that CCL5 participates in hippocampal fructose and mannose degradation, glycolysis, gluconeogenesis as well as glutamate and purine metabolism. CCL5 additionally supports mitochondrial structural integrity, purine synthesis, ATP generation, and subsequent aerobic glucose metabolism. Overexpressing CCL5 in WT mice also enhanced memory-cognition performance as well as hippocampal neuronal activity and connectivity through promotion of de novo purine and glutamate metabolism. Thus, CCL5 actions on glucose aerobic metabolism are critical for mitochondrial function which contribute to hippocampal spine and synapse formation, improving learning and memory.

Evidence for gene-smoking interactions for hearing loss and deafness in Japanese American families

BACKGROUND

This study investigated the relationship between smoking and hearing loss and deafness (HLD) and whether the relationship is modified by genetic variation. Data for these analyses was from the subset of Japanese American families collected as part of the American Diabetes Association Genetics of Non-insulin Dependent Diabetes Mellitus study. Logistic regression with generalized estimating equations assessed the relationship between HLD and smoking. Nonparametric linkage analysis identified genetic regions harboring HLD susceptibility genes and ordered subset analysis was used to identify regions showing evidence for gene-smoking interactions. Genetic variants within these candidate regions were then each tested for interaction with smoking using logistic regression models.

RESULTS

After adjusting for age, sex, diabetes status and smoking duration, for each pack of cigarettes smoked per day, risk of HLD increased 4.58 times (odds ratio (OR) = 4.58; 95% Confidence Interval (CI): (1.40,15.03)), and ever smokers were over 5 times more likely than nonsmokers to report HLD (OR = 5.22; 95% CI: (1.24, 22.03)). Suggestive evidence for linkage for HLD was observed in multiple genomic regions (Chromosomes 5p15, 8p23 and 17q21), and additional suggestive regions were identified when considering interactions with smoking status (Chromosomes 7p21, 11q23, 12q32, 15q26, and 20q13) and packs-per-day (Chromosome 8q21).

CONCLUSIONS

To our knowledge this was the first report of possible gene-by-smoking interactions in HLD using family data. Additional work, including independent replication, is needed to understand the basis of these findings. HLD are important public health issues and understanding the contributions of genetic and environmental factors may inform public health messages and policies.

Computational analysis of receptor tyrosine kinase inhibitors and cancer metabolism: implications for treatment and discovery of potential therapeutic signatures

BACKGROUND

Receptor tyrosine kinase (RTK) inhibitors are frequently used to treat cancers and the results have been mixed, some of these small molecule drugs are highly successful while others show a more modest response. A high number of studies have been conducted to investigate the signaling mechanisms and corresponding therapeutic influence of RTK inhibitors in order to explore the therapeutic potential of RTK inhibitors. However, most of these studies neglected the potential metabolic impact of RTK inhibitors, which could be highly associated with drug efficacy and adverse effects during treatment.

METHODS

In order to fill these knowledge gaps and improve the therapeutic utilization of RTK inhibitors a large-scale computational simulation/analysis over multiple types of cancers with the treatment responses of RTK inhibitors was performed. The pharmacological data of all eight RTK inhibitor and gene expression profiles of 479 cell lines from The Cancer Cell Line Encyclopedia were used.

RESULTS

The potential metabolic impact of RTK inhibitors on different types of cancers were analyzed resulting in cancer-specific (breast, liver, pancreas, central nervous system) metabolic signatures. Many of these are in line with results from different independent studies, thereby providing indirect verification of the obtained results.

CONCLUSIONS

Our study demonstrates the potential of using a computational approach on signature-based-analysis over multiple cancer types. The results reveal the strength of multiple-cancer analysis over conventional signature-based analysis on a single cancer type.

Yeast to Study Human Purine Metabolism Diseases

Purine nucleotides are involved in a multitude of cellular processes, and the dysfunction of purine metabolism has drastic physiological and pathological consequences. Accordingly, several genetic disorders associated with defective purine metabolism have been reported. The etiology of these diseases is poorly understood and simple model organisms, such as yeast, have proved valuable to provide a more comprehensive view of the metabolic consequences caused by the identified mutations. In this review, we present results obtained with the yeast Saccharomyces cerevisiae to exemplify how a eukaryotic unicellular organism can offer highly relevant information for identifying the molecular basis of complex human diseases. Overall, purine metabolism illustrates a remarkable conservation of genes, functions and phenotypes between humans and yeast.

Fibril formation and therapeutic targeting of amyloid-like structures in a yeast model of adenine accumulation

The extension of the amyloid hypothesis to include non-protein metabolite assemblies invokes a paradigm for the pathology of inborn error of metabolism disorders. However, a direct demonstration of the assembly of metabolite amyloid-like structures has so far been provided only in vitro. Here, we established an in vivo model of adenine self-assembly in yeast, in which toxicity is associated with intracellular accumulation of the metabolite. Using a strain blocked in the enzymatic pathway downstream to adenine, we observed a non-linear dose-dependent growth inhibition. Both the staining with an indicative amyloid dye and anti-adenine assemblies antibodies demonstrated the accumulation of adenine amyloid-like structures, which were eliminated by lowering the supplied adenine levels. Treatment with a polyphenol inhibitor reduced the occurrence of amyloid-like structures while not affecting the dramatic increase in intracellular adenine concentration, resulting in inhibition of cytotoxicity, further supporting the notion that toxicity is triggered by adenine assemblies.

Small molecule metabolites like phenylalanine can form amyloid-like structures but so far this has only been demonstrated in vitro. Here the authors generate a yeast in vivo model of adenine self-assembly and characterize the adenine assemblies in cells by indicative amyloid dye and anti-adenine assemblies antibodies.

MRI findings of hypomyelination in adenylosuccinate lyase deficiency

Adenylosuccinate lyase deficiency is a rare genetic disorder with few reported cases in the United States. Magnetic resonance imaging findings in the brain include hypomyelination and low generalized parenchymal volume. Presented here is a case in a 3-month-old male who presented with hypotonia and seizures and was subsequently diagnosed with adenylosuccinate lyase deficiency. Given the rarity of this diagnosis, findings demonstrated in this case may prompt ordering physicians to broaden their approach to genetic testing in the setting of hypomyelination. Comparison is also made to more common hypomyelinating leukodystrophies.

Prophylactic ketamine alters nucleotide and neurotransmitter metabolism in brain and plasma following stress

Recently, we have shown that ketamine given prior to stress exposure protects against the development of depressive-like behavior in mice. These data suggest that it may be possible to prevent the induction of affective disorders before they develop by administering prophylactic pharmaceuticals, a relatively nascent and unexplored strategy for psychiatry. Here, we performed metabolomics analysis of brain and plasma following prophylactic ketamine treatment in order to identify markers of stress resilience enhancement. We administered prophylactic ketamine in mice to buffer against fear expression. Following behavioral analyses, untargeted metabolomic profiling was performed on both hemispheres of the prefrontal cortex (PFC) and the hippocampus (HPC), and plasma. We found that prophylactic ketamine attenuated learned fear. Eight metabolites were changed in the PFC and HPC upon ketamine treatment. Purine and pyrimidine metabolism were most significantly changed in the HPC, PFC, and, interestingly, plasma of mice two weeks after prophylactic administration. Moreover, most precursors to inhibitory neurotransmitters were increased whereas precursors to excitatory neurotransmitters were decreased. Strikingly, these long-term metabolomic changes were not observed when no stressor was administered. Our results suggest that prophylactic treatment differentially affects purine and pyrimidine metabolism and neurotransmission in brain and plasma following stress, which may underlie the long-lasting resilience to stress induced by a single injection of ketamine. These data may provide novel targets for prophylactic development, and indicate an interaction effect of prophylactic ketamine and stress. To our knowledge, this is the first study that identifies metabolomic alterations and biomarker candidates for prophylactic ketamine efficacy in mice.

Development and Validation of a Simple High Performance Liquid Chromatography/UV Method for Simultaneous Determination of Urinary Uric Acid, Hypoxanthine, and Creatinine in Human Urine

Uric acid and hypoxanthine are produced in the catabolism of purine. Abnormal urinary levels of these products are associated with many diseases and therefore it is necessary to have a simple and rapid method to detect them. Hence, we report a simple reverse phase high performance liquid chromatography (HPLC/UV) technique, developed and validated for simultaneous analysis of uric acid, hypoxanthine, and creatinine in human urine. Urine was diluted appropriately and eluted with C-18 column 100 mm × 4.6 mm with a C-18 precolumn 25 mm × 4.6 mm in series. Potassium phosphate buffer (20 mM, pH 7.25) at a flow rate of 0.40 mL/min was employed as the solvent and peaks were detected at 235 nm. Tyrosine was used as the internal standard. The experimental conditions offered a good separation of analytes without interference of endogenous substances. The calibration curves were linear for all test compounds with a regression coefficient, r2 > 0.99. Uric acid, creatinine, tyrosine, and hypoxanthine were eluted at 5.2, 6.1, 7.2, and 8.3 min, respectively. Intraday and interday variability were less than 4.6% for all the analytes investigated and the recovery ranged from 98 to 102%. The proposed HPLC procedure is a simple, rapid, and low cost method with high accuracy with minimum use of organic solvents. This method was successfully applied for the determination of creatinine, hypoxanthine, and uric acid in human urine.

Pathophysiological Role of Purines and Pyrimidines in Neurodevelopment: Unveiling New Pharmacological Approaches to Congenital Brain Diseases

In recent years, a substantial body of evidence has emerged demonstrating that purine and pyrimidine synthesis and metabolism play major roles in controlling embryonic and fetal development and organogenesis. Dynamic and time-dependent changes in the expression of purine metabolizing enzymes (such as ectonucleotidases and adenosine deaminase) represent a key checkpoint for the correct sequential generation of the different signaling molecules, that in turn activate their specific membrane receptors. In neurodevelopment, Ca²⁺ release from radial glia mediated by P2Y₁ purinergic receptors is fundamental to allow neuroblast migration along radial glia processes, and their correct positioning in the different layers of the developing neocortex. Moreover, ATP is involved in the development of synaptic transmission and contributes to the establishment of functional neuronal networks in the developing brain. Additionally, several purinergic receptors (spanning from adenosine to P2X and P2Y receptor subtypes) are differentially expressed by neural stem cells, depending on their maturation stage, and their activation tightly regulates cell proliferation and differentiation to either neurons or glial cells, as well as their correct colonization of the developing telencephalon. The purinergic control of neurodevelopment is not limited to prenatal life, but is maintained in postnatal life, when it plays fundamental roles in controlling oligodendrocyte maturation from precursors and their terminal differentiation to fully myelinating cells. Based on the above-mentioned and other literature evidence, it is now increasingly clear that any defect altering the tight regulation of purinergic transmission and of purine and pyrimidine metabolism during pre- and post-natal brain development may translate into functional deficits, which could be at the basis of severe pathologies characterized by mental retardation or other disturbances. This can occur either at the level of the recruitment and/or signaling of specific nucleotide or nucleoside receptors or through genetic alterations in key steps of the purine salvage pathway. In this review, we have provided a critical analysis of what is currently known on the pathophysiological role of purines and pyrimidines during brain development with the aim of unveiling new future strategies for pharmacological intervention in different neurodevelopmental disorders.

Glucose 6 phosphatase dehydrogenase (G6PD) and neurodegenerative disorders: Mapping diagnostic and therapeutic opportunities

Glucose 6 phosphate dehydrogenase (G6PD) is a key and rate limiting enzyme in the pentose phosphate pathway (PPP). The physiological significance of enzyme is providing reduced energy to specific cells like erythrocyte by maintaining co-enzyme nicotinamide adenine dinucleotide phosphate (NADPH). There are preponderance research findings that demonstrate the enzyme (G6PD) role in the energy balance, and it is associated with blood-related diseases and disorders, primarily the anemia resulted from G6PD deficiency. The X-linked genetic deficiency of G6PD and associated non-immune hemolytic anemia have been studied widely across the globe. Recent advancement in biology, more precisely neuroscience has revealed that G6PD is centrally involved in many neurological and neurodegenerative disorders. The neuroprotective role of the enzyme (G6PD) has also been established, as well as the potential of G6PD in oxidative damage and the Reactive Oxygen Species (ROS) produced in cerebral ischemia. Though G6PD deficiency remains a global health issue, however, a paradigm shift in research focusing the potential of the enzyme in neurological and neurodegenerative disorders will surely open a new avenue in diagnostics and enzyme therapeutics. Here, in this study, more emphasis was made on exploring the role of G6PD in neurological and inflammatory disorders as well as non-immune hemolytic anemia, thus providing diagnostic and therapeutic opportunities.

Hypoxanthine Induces Neuroenergetic Impairment and Cell Death in Striatum of Young Adult Wistar Rats

Hypoxanthine is the major purine involved in the salvage pathway of purines in the brain. High levels of hypoxanthine are characteristic of Lesch-Nyhan Disease. Since hypoxanthine is a purine closely related to ATP formation, the aim of this study was to investigate the effect of intrastriatal hypoxanthine administration on neuroenergetic parameters (pyruvate kinase, succinate dehydrogenase, complex II, cytochrome c oxidase, and ATP levels) and mitochondrial function (mitochondrial mass and membrane potential) in striatum of rats. We also evaluated the effect of cell death parameters (necrosis and apoptosis). Wistar rats of 60 days of life underwent stereotactic surgery and were divided into two groups: control (infusion of saline 0.9%) and hypoxanthine (10 μM). Intrastriatal hypoxanthine administration did not alter pyruvate kinase activity, but increased succinate dehydrogenase and complex II activities and diminished cytochrome c oxidase activity and immunocontent. Hypoxanthine injection decreased the percentage of cells with mitochondrial membrane label and increased mitochondrial membrane potential labeling. There was a decrease in the number of live cells and an increase in the number of apoptotic cells by caused hypoxanthine. Our findings show that intrastriatal hypoxanthine administration altered neuroenergetic parameters, and caused mitochondrial dysfunction and cell death by apoptosis, suggesting that these processes may be associated, at least in part, with neurological symptoms found in patients with Lesch-Nyhan Disease.

Role of Genetics in the Etiology of Autistic Spectrum Disorder: Towards a Hierarchical Diagnostic Strategy

Progress in epidemiological, molecular and clinical genetics with the development of new techniques has improved knowledge on genetic syndromes associated with autism spectrum disorder (ASD). The objective of this article is to show the diversity of genetic disorders associated with ASD (based on an extensive review of single-gene disorders, copy number variants, and other chromosomal disorders), and consequently to propose a hierarchical diagnostic strategy with a stepwise evaluation, helping general practitioners/pediatricians and child psychiatrists to collaborate with geneticists and neuropediatricians, in order to search for genetic disorders associated with ASD. The first step is a clinical investigation involving: (i) a child psychiatric and psychological evaluation confirming autism diagnosis from different observational sources and assessing autism severity; (ii) a neuropediatric evaluation examining neurological symptoms and developmental milestones; and (iii) a genetic evaluation searching for dysmorphic features and malformations. The second step involves laboratory and if necessary neuroimaging and EEG studies oriented by clinical results based on clinical genetic and neuropediatric examinations. The identification of genetic disorders associated with ASD has practical implications for diagnostic strategies, early detection or prevention of co-morbidity, specific treatment and follow up, and genetic counseling.

Hyperuricemia in Children and Adolescents with Autism Spectrum Disorder Treated with Risperidone: The Risk Factors for Metabolic Adverse Effects

Background: Atypical antipsychotics have been found to be associated with hyperuricemia. Risperidone, one of the atypical antipsychotics, might be related to the hyperuricemia among autism spectrum disorder (ASD) patients. The aims of this study were to determine the prevalence of hyperuricemia in ASD patients treated with risperidone and to determine associations between serum uric acid levels and risperidone dosage, treatment duration, and metabolic parameters. Methods: 127 children and adolescents with ASD treated with risperidone and 76 age-matched risperidone-naïve patients with ASD were recruited. The clinical data and laboratory data were analyzed. Hyperuricemia was defined as serum uric acid >5.5 mg/dl. Results: Hyperuricemia was present in 44.70% of risperidone-naïve patients with ASD and 57.50% of ASD patients treated with risperidone. The fasting uric acid levels were significantly higher in the risperidone group than in the risperidone-naïve group (5.70 vs. 5.35 mg/dl, P = 0.01). The increased uric acid concentrations were significantly associated with adolescent patients treated with risperidone. The higher dose of risperidone and/or the longer treatment time were associated with the increased uric acid levels. Uric acid levels significantly rose with body mass index (BMI), waist circumference (WC), triglyceride (TG) levels, triglycerides to high-density lipoprotein cholesterol ratio (TG/HDL-C), insulin levels, homeostatic model assessment index (HOMA-IR), high-sensitivity CRP (hs-CRP) levels, and leptin levels. Conversely, the levels of HDL-C and adiponectin were negatively correlated with uric acid levels. In multiple regression analysis, there were age, BMI, TG/HDL-C ratio, and adiponectin levels remained significantly associated with uric acid levels. Conclusion: Hyperuricemia may play a role in metabolic adverse effect in children and adolescents with ASDs receiving the high dose and/or the long-term treatment with risperidone.

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Zusammenfassung. Muskelkrämpfe sind sehr häufig und treten sowohl bei gesunden Menschen als auch im Rahmen von verschiedenen internistischen, rheumatologischen und neurologischen krankhaften Zuständen auf. Muskelkrämpfe bei gesunden Menschen sind selbstlimitierend und in der Regel auf körperliche Überbelastung zurückzuführen. Bei persistierenden, heftigen und therapieresistenten Muskelkrämpfen sollte eine Abklärung durchgeführt werden, wobei hier die Suche nach behandelbaren Ursachen im Vordergrund steht (z.B. mangelhafte Hydratation, muskuläre Überbelastung, Elektrolytverschiebungen, Dysthyreose, Vitaminmangel, Niereninsuffizienz, Leberzirrhose, medikamentös-toxische Nebenwirkungen etc.). Nach Ausschluss solcher symptomatischer Ursachen kann eine neurologische Abklärung zur Suche nach spezifischen neuromuskulären und neurologischen Erkrankungen sinnvoll sein. Primär sollte immer eine kausale Behandlung angestrebt werden. Auch Allgemeinmassnahmen wie Vermeiden krampfauslösender Belastungen, ausreichende Flüssigkeitszufuhr und abendliche Dehnungsübungen sollten instruiert werden. Zur symptomatischen Behandlung von Muskelkrämpfen haben mehrere Medikamente, insbesondere Magnesiumpräparate und Chininsulfat, Wirksamkeit gezeigt. Allerdings stehen keine doppelblinden und Placebo-kontrollierten Studiendaten zur Verfügung.

Chronic alcohol administration affects purine nucleotide catabolism in vivo

AIMS

To investigate the relationship between chronic alcohol administration and purine nucleotide metabolism in vivo.

MAIN METHODS

Rat models of alcohol dependence and withdrawal were used. The concentrations of uric acid (UAC), urea nitrogen (UREA), creatinine (CREA), and beta-2-microglobulin (β2-M) and creatinine clearance rate (CCR) in plasma were measured. The PLC method was used to detect the absolute content of purine nucleotides in different tissues. Enzymatic activities of adenosine deaminase (ADA), xanthine oxidase (XO), ribose 5-phosphate pyrophosphokinase (RPPPK), glutamine phosphoribosylpyrophosphate amidotransferase (GPRPPAT), hypoxanthine-guanine phosphate ribose transferase (HGPRT), and adenine phosphoribosyltransferase (APRT) in the tissues were analyzed. Real-time PCR was used to determine the relative level of ADA and XO.

KEY FINDINGS

The renal function of rats with alcohol dependence was normal. Further, the content of purine nucleotides (GMP, AMP, GTP, and ATP) in tissues of the rats was decreased, which indicated that the increased uric acid should be derived from the decomposition of nucleotides in vivo. The activity of XO and ADA increased, and their mRNA expression was enhanced in the alcohol dependence group, but there was no significant difference in the activity of RPPPK and GPRPPAT in the liver, small intestine, and muscle; furthermore, no significant difference in the activity of HGPRT and APRT was observed in the brain.

SIGNIFICANCE

These results indicate that chronic alcohol administration might enhance the catabolism of purine nucleotides in tissues by inducing gene expression of ADA and XO, leading to elevation of plasma uric acid levels.

Adenosine deaminase and adenosine kinase expression in human glioma and their correlation with glioma‑associated epilepsy

The aim of the present study was to investigate adenosine deaminase (ADA) and adenosine kinase (ADK) expression in human glioma and to explore its correlation with glioma-associated epilepsy. Tumor tissues (n=45) and peritumoral tissues (n=14) were obtained from glioma patients undergoing surgery. Normal control tissues (n=8) were obtained from brain trauma patients. The disease grade was determined by histological evaluation and the degree of tumor invasion was evaluated using immunofluorescence analyses. mRNA and protein expression of ADA and ADK were evaluated using reverse transcription quantitative polymerase chain reaction or western blot analysis, respectively. Based on histological evaluations, four cases were classified as Grade I gliomas, 18 cases as Grade II, 17 cases as Grade III and six cases were considered Grade IV. Increased ADA and ADK expression was observed in tumor tissues. ADA was predominantly distributed in the cytoplasm of tumor cells, whereas ADK was detected in the cytoplasm as well as in the nuclei. ADA and ADK levels were upregulated in patients with Grade II and Grade III gliomas compared to those in control subjects (p<0.05). In addition, tumor invasion was detected in peritumoral tissues. The number of ADA-positive or ADK-positive cells in tumor tissues was similar between glioma patients with and without epilepsy (p>0.05). However, ADA and ADK expression was upregulated in peritumoral tissues derived from patients with epilepsy compared to that in glioma patients without epilepsy. The results of the present study suggested that ADA and ADK are involved in glioma progression, and that increased ADA and ADK levels in peritumoral tissues may be associated with epilepsy in glioma patients.