Glucose-6-phosphate Dehydrogenase Research Articles

Phytochemical Analysis, Total Phenolic Content, Hemolytic and Anti-hemolytic Activities of Centaurea iberica (Asteraceae)

Several plants contain chemical substances that have various biological activities, but they also probably cause harmful effects on cellular membranes. This work deals with the Centaurea iberica (Iberian starthistle) plant. The objective of this study is to identify the main chemical groups in the methanolic extract 80% of the plant, determine its total phenolic content, evaluate its toxic effect on human erythrocytes, and also assess its activity in the protection of normal and glucose-6-phosphate dehydrogenase (G6PD) enzyme-deficient human erythrocytes membranes against oxidative hemolysis. Phytochemical analysis revealed that C. iberica extract contains several bioactive compounds. The results also showed that the plant extract contained good level of total phenolic compounds. The extract exhibited a low hemolytic effect. It also showed excellent activity in the protection of normal and G6PD-deficient human erythrocytes against oxidative hemolysis. KEYWORDS Erythrocytes, G6PD, Iberian starthistle, methanolic extract, toxic effect, oxidative hemolysis

Case report: Dichloroacetate-induced methaemoglobinaemia in a G6PD-deficient neonate.

A 3-week-old neonate with glucose-6-phosphate dehydrogenase (G6PD) deficiency and primary lactic acidosis developed haemolytic jaundice and methaemoglobinaemia following treatment with dichloroacetate (DCA), a standard treatment for primary lactic acidosis. While this mechanism has been reported in the sheep model, it has not been described in humans. Our case reinforces the uncommon observation that a G6PD-deficient individual experiencing oxidative stress may develop concurrent methaemoglobinaemia. In this case, methylene blue, the standard treatment for methaemoglobinaemia, may result in further oxidative stress. The judicious use of blood transfusion to correct the oxygen-carrying capacity of our patient led to reversal of the methaemoglobinaemia.

Molecular epidemiological characteristics, variant spectrum and genotype-phenotype correlation of glucose-6-phosphate dehydrogenase deficiency in China: A population-based multicenter study using newborn screening.

Newborn screening (NBS) for glucose-6-phosphate dehydrogenase (G6PD) deficiency by biochemical tests is being used worldwide, however, the outcomes arising from combined genetic and biochemical tests have not been evaluated. This research aimed to evaluate the outcomes of application of combined genetic and biochemical NBS for G6PD deficiency and to investigate the molecular epidemiological characteristics, variant spectrum, and genotype-phenotype correlation of G6PD deficiency in China. A population-based cohort of 29,601 newborns were prospectively recruited from eight NBS centers in China between February 21 and December 30, 2021. Biochemical and genetic NBS was conducted simultaneously. The overall prevalence of G6PD deficiency was 1.12% (1.86% for male, and 0.33% for female; 1.94% for South China and 0.08% for North China). Genetic NBS identified 10 male patients undetected by biochemical NBS. The overall positive predictive values (PPVs) of biochemical and genetic NBS were 79.95% and 47.57%, respectively. A total of 15 variants were identified, with the six most common variants being c.1388G > A, c.1376G > T, c.95A > G, c.871G > A, c.1024C > T and c.392G > T (94.2%). The activity of G6PD was correlated with the type and WHO classification of variants. This study highlighted that combined screening could enhance the efficiency of current NBS for diagnosing G6PD deficiency. The prevalence, variant spectrum and allele frequency of G6PD deficiency vary across different regions. Our data provide valuable references for clinical practice and optimization of future screening strategies for G6PD deficiency.

G>A transition at 376 position of the glucose-6-phosphate dehydrogenase (G6PD) gene plays a key role in causing G6PD deficiency in the Siddi population of Karnataka.

G>A transition at 376 position of the glucose-6-phosphate dehydrogenase (G6PD) gene plays a key role in causing G6PD deficiency in the Siddi population of Karnataka.

Supplemental oxygen alters the pentose phosphate pathway in the developing mouse brain through SIRT signaling

Oxygen support plays a critical role in the management of preterm infants in neonatal intensive care units. On the other hand, the possible effects of oxygen supplementation on cellular functions, specifically glucose metabolism, have been less understood. Purposeof the study is to investigate whether supplemental oxygen alters glucose metabolism and pentose phosphate pathway (PPP) activity in the brain tissue and its relevance with silent information regulator proteins (SIRT) pathway. For this purpose, newborn C57BL/6 pups were exposed to 90% oxygen from birth until postnatal day 7 (PN7) and metabolites of glysolysis and PPP were investigated through metabolomics analysis. SIRT1, glucose-6-phosphate dehydrogenase (G6PD) and transaldolase (TALDO) proteins were examined immunohistochemically and molecularly in the prefrontal and hippocampus regions of the brain. Later on, SIRT1 inhibition was carried out.Our results indicate that supplemental oxygen causes an increase in PPP metabolites as well as activation of G6PD enzyme in the brain tissue, which is reversed by SIRT1 inhibition. Our study underlines a connection between supplemental oxygen, glucose metabolism, PPP pathway and the SIRT signaling. Understanding these intricate relationships not only deepens our knowledge of cellular physiology but also holds promise for therapeutic interventions for creating neuroprotective strategies in preterm brain.

Expanding families: a pilot study on preconception expanded carrier screening in Bahrain

BackgroundPreconception expanded carrier screening (ECS) is a genetic test that enables the identification of at-risk carriers of recessive disorders by screening for up to hundreds of genes. Next-generation sequencing (NGS) development has paved the way for its integration into ECS. This study aims to identify the carrier genetic status of couples experiencing or anticipating conception challenges through NGS-based ECS and to gain an overview of the rare genetic disorders in a population with increased consanguinity.MethodsThirty couples who presented to the Genetic Disease Clinic between 2015 and 2024 with failed reproductive outcomes or with a positive personal or family history of genetic disorders and underwent ECS were included and retrospectively analyzed.ResultsFifty-four individuals (90.00%) were found to carry at least one variant of 95 identified genes, totaling 174 variants. Six individuals (10.00%) tested negative for any variant. Seven individuals had one variant (11.67%), 13 had two variants (21.67%), and 34 had 3 or more variants (56.67%). The most common variants identified were of HBA, HBB, CYP21A2, and G6PD genes. Most of the detected variants were unknown or unexpected (n = 143, 82.18%). Eight couples carried two or more variants in common. Consanguinity was reported in 14 couples (46.67%).ConclusionsPreconception ECS is crucial for reproductive planning, permitting couples to evaluate their combined genetic risks and make informed decisions, reducing the chance of having children with genetic disorders.

Buffy coat removal to mitigate reporting false normal G6PD phenotype results in patients undergoing rasburicase therapy for tumor lysis syndrome

Abstract Glucose-6-phosphate dehydrogenase (G6PD) is the primary source of NADPH in red blood cells (RBCs). NADPH reduces reactive oxygen species (ROS) thereby protecting RBCs from oxidative stress-mediated hemolytic anemia (HA). Individuals with partial or full G6PD deficiency are therefore susceptible to acute HA provoked by medications that generate high ROS loads in vivo, e.g., rasburicase. Rasburicase is an enzyme-based therapeutic used to degrade uric acid (UA) in patients with tumor lysis syndrome (TLS); however, catalysis of UA generates H2O2, a potent ROS, which poses a risk of HA in individuals who are deficient in G6PD activity. Screening G6PD activity prior to rasburicase administration is clinically indicated in ethnic groups with high rates of G6PD deficiency, although reports of HA in rasburicase-treated patients have been reported across low prevalence ethnic groups as well. TLS occurs most commonly during the treatment of highly proliferative neoplasms, such as leukemia and lymphoma. Since WBCs contain significant G6PD activity, an elevated WBC count in these patients can cause the false assurance of low HA risk due to a falsely normal G6PD activity. We sought to establish and evaluate a novel method to mitigate WBC contamination of G6PD measurements in patients undergoing rasburicase therapy. In this study, we first developed and validated an innovative method (“piercing method”) to minimize the interference of WBCs in G6PD measurements. The piercing method demonstrated acceptable accuracy (slope: 1.008; bias: -6.22%) and precision (1.4% CV between 9.9 to 20.7 U/g Hb) and was effective at eliminating a broad range of WBC types and concentrations from whole blood samples (N = 85, tested range = 0.31 – 413.05 K/μL, 93% reduction in WBCs). We compared G6PD activity in rasburicase-treated patients (N = 39) with varying WBC counts before and after buffy coat removal using the piercing method. Average percent change in G6PD activity (post-pierce – pre-pierce) between patients with and without elevated WBCs was substantial (45% versus 12%). In comparing G6PD activity in patients before and after the initiation of rasburicase therapy, there is no evidence that in vivo-generated ROS from rasburicase affect G6PD measurement in vitro in an assay that relies on monitoring absorbance of NADPH (22.2 U/g Hb versus 22.9 U/g Hb, p=0.721). Results demonstrate how WBCs increase risk for false elevation in G6PD activity in patients being considered for rasburicase therapy. At greatest risk are patients with partial G6PD deficiency, e.g., heterozygous females, where G6PD from WBCs could mask deficiency. Literature describing testing of G6PD in specimens with elevated WBCs is lacking. This study shows that the piercing method provides accurate G6PD results in samples with elevated WBCs from patients at risk of TLS, who might develop HA after starting rasburicase therapy.

Change in Activities of Enzymes of Energy and Carbohydrate Metabolism in Pink Salmon Oncorhynchus gorbuscha (Walb.) Smolts with Change in Environmental Salinity.

Activities of key enzymes of energy and carbohydrate metabolism (cytochrome c oxidase (COX), lactate dehydrogenase (LDH), aldolase, glucose 6-phosphate dehydrogenase (G6PDH), and 1-glycerophosphate dehydrogenase (1-GPDH)) were studied in pink salmon Oncorhynchus gorbuscha (Walb.) smolts from the White Sea in a cage experiment simulating the transition from a freshwater to a marine environment. A decrease in COX, G6PDH, and 1-GPDH activities and an increase in LDH and aldolase activities were observed in juveniles with an increase in water salinity. Based on the findings, a redistribution of energy substrates between the reactions of aerobic and anaerobic metabolism towards higher anaerobic ATP synthesis was assumed for pink salmon. This may indicate that adaptive mechanisms rearrange metabolism to provide energy for osmoregulation in pink salmon juveniles when the salinity changes in their habitat.

Identification of a novel NADPH generation reaction in the pentose phosphate pathway in Escherichia coli using mBFP.

NADPH is a redox cofactor that drives the anabolic reactions. Although major NADPH generation reactions have been identified in Escherichia coli, some minor reactions have not been identified. In the present study, we explored novel NADPH generation reactions by monitoring the fluorescence dynamics after the addition of carbon sources to starved cells, using a metagenome-derived blue fluorescent protein (mBFP) as an intracellular NADPH reporter. Perturbation analyses were performed on a glucose-6-phosphate isomerase (PGI) deletion strain and its parental strain. Interestingly, mBFP fluorescence increased not only in the parental strain but also in the ΔPGI strain after the addition of xylose. Because the ΔPGI strain cannot metabolize xylose through the oxidative pentose phosphate pathway, this suggests that an unexpected NADPH generation reaction contributes to an increase in fluorescence. To unravel this mystery, we deleted the NADPH generation enzymes including transhydrogenase, isocitrate dehydrogenase, NADP+-dependent malic enzyme, glucose-6-phosphate dehydrogenase (G6PDH), and 6-phosphogluconate dehydrogenase (6PGDH) in the ΔPGI strain, and revealed that G6PDH and 6PGDH contribute to an increase in fluorescence under xylose conditions. In vitro assays using purified enzymes showed that G6PDH can produce NADPH using erythrose-4-phosphate (E4P) as a substitute for glucose-6-phosphate. Because the Km (0.65 mM) for E4P was much higher than the reported intracellular E4P concentrations in E. coli, little E4P must be metabolized through this bypass in the parental strain. However, the flux would increase when E4P accumulates in the cells owing to genetic modifications. This finding provides a metabolic engineering strategy for generating NADPH to produce useful compounds using xylose as a carbon source.IMPORTANCEBecause NADPH is consumed during the synthesis of various useful compounds, enhancing NADPH regeneration is highly desirable in metabolic engineering. In this study, we explored novel NADPH generation reactions in Escherichia coli using a fluorescent NADPH reporter and found that glucose-6-phosphate dehydrogenase can produce NADPH using erythrose-4-phosphate as a substrate under xylose conditions. Xylose is an abundant sugar in nature and is an attractive carbon source for bioproduction. Therefore, this finding contributes to novel pathway engineering strategies using a xylose carbon source in E. coli to produce useful compounds that consume NADPH for their synthesis.

Stoichiometric Regeneration of Biomimetic Nicotinamide Coenzyme Powered by Biomass Sugars via In Vitro Synthetic Enzymatic Biosystems.

Biomimetic nicotinamide coenzymes, including nicotinamide mononucleotide (NMN+), have been demonstrated as promising low-cost alternatives to nicotinamide adenine dinucleotide (phosphate) (NAD(P)+) in biocatalysis. Herein, to efficiently regenerate NMNH from NMN+ in vitro powered by biomass sugars, a thermophilic NADP+-dependent glucose 6-phosphate dehydrogenase from Thermotoga maritima (TmG6PDH) was engineered to increase the activity toward NMN+. The catalytic efficiency (kcat/Km) of optimal mutant (TmG6PDH-R7) toward NMN+ increased by 71.7-fold than TmG6PDH-WT. As a result, compared to the wild type, the coenzyme specificity ([kcat/Km]NMN+/[kcat/Km]NADP+) of TmG6PDH-R7 increased by ~2.0×105-fold. The structural analysis revealed that the introduced hydrophobic and bulky residues lead to the formation of a smaller binding pocket, which resulting in a higher affinity for NMN+ with small size than NADP+. Then several in vitro synthetic enzymatic biosystems (ivSEBs) comprising this thermophilic TmG6PDH-R7 and a previously engineered thermophilic 6-phosphogluconate dehydrogenase were constructed. These ivSEBs harnessed the complete oxidation of renewable biomass sugars to facilitate the stoichiometric regeneration of 12 molecules of NMNH from 1 molecule of glucose, thereafter producing various products such as levodione, 2,3-butanediol or bioelectricity, over a wide temperature range. This study could pave the way for using stable and low-cost biomimetic coenzymes in ivSEBs for industrial biomanufacturing.

In Silico Approach for Assessment of the Anti-tumor Potential of Cannabinoid Compounds by Targeting Glucose-6-Phosphate Dehydrogenase Enzyme.

Glucose-6-phosphate dehydrogenase (G6PD) is a pentose phosphate pathway (PPP) enzyme that generates NADPH, which is required for cellular redox equilibrium and reductive biosynthesis. It has been demonstrated that abnormal G6PD activation promotes cancer cell proliferation and metastasis. To date, no G6PD inhibitor has passed clinical testing successfully enough to be launched as a medicine. As a result, in this investigation, cannabinoids were chosen to evaluate their anticancer potential by targeting G6PD. Molecular docking indicated that three molecules, Tetrahydrocannabinolic acid (THCA), Cannabichromenic acid (CBCA), and tetrahydrocannabivarin (THCV), have the highest binding affinities for G6PD of -8.61, -8.39, and 8.01 Kcal mol. ADMET analysis found that all of them were safe prospective drug candidates. Molecular dynamics (MD) simulation and MM-PBSA analysis confirm the structural compactness and lower conformational variation of protein-ligand complexes, thereby maintaining structural stability and rigidity. Thus, our in silico investigation exhibited all three cannabinoids as potential competitive inhibitors of G6PD.

Bioorthogonal Regulated Metabolic Balance for Promotion of Ferroptosis and Mild Photothermal Therapy.

The nanozyme with NADPH oxidase (NOX)-like activity can promote the consumption of NADPH and the generation of free radicals. In consideration of that the upregulation of glucose-6-phosphate dehydrogenase (G6PD) would accelerate the compensation production of NADPH, for inhibition of G6PD activity, our designed bioorthogonal nanozyme can in situ catalyze pro-DHEA to produce G6PD inhibitor and dehydroepiandrosterone (DHEA) drugs to inhibit G6PD activity. Therefore, the well-defined platform can disrupt NADPH homeostasis, leading to the collapse of the antioxidant defense system in the tumor cells. The enzyme-like activity of PdCuFe is further enhanced when irradiated by NIR-II light. The destruction of NADPH homeostasis can promote ferroptosis and, in turn, facilitate mild photothermal therapy. Our design can realize NADPH depletion and greatly improve the therapeutic effect through metabolic regulation, which may provide inspiration for the design of bioorthogonal catalysis.

Controversies in our understanding of extreme hyperbilirubinemia in glucose-6-phosphate dehydrogenase-deficient neonates.

Despite declarations that kernicterus should be a "never-event", the condition continues to occur, glucose-6-phosphate dehydrogenase (G6PD)-deficiency being a leading cause. In this paper, we address some controversies regarding the pathophysiology and the potential for extreme hyperbilirubinemia associated with G6PD-deficiency. We present evidence to demonstrate that G6PD-deficiency-associated neonatal hyperbilirubinemia is no longer limited to countries and geographic regions to which the condition was indigenous, but is also encountered in North America and other Western countries with a low inherent G6PD-deficiency frequency. Pathophysiologically, while a diminished bilirubin conjugative component is undoubtedly present, we present evidence that there is a component of increased hemolysis as well, contributing to the extreme, exponential hyperbilirubinemia associated with G6PD-deficiency. Extreme hyperbilirubinemia in G6PD heterozygotes, while less frequent than in male hemizygotes or female deficient homozygotes, has been reported, suggesting previous underestimation of the risks of heterozygosity. Universal neonatal screening for G6PD-deficiency, while not expected to prevent acute, episodic hyperbilirubinemia, should increase awareness, thereby facilitating earlier referral for treatment, prior to the onset of bilirubin encephalopathy. Finally, we speculate as to what the future looks like for babies with G6PD-deficiency, potential therapeutic stratagems, and the effect of G6PD-deficiency on medical conditions beyond the realm of neonatal hyperbilirubinemia. IMPACT STATEMENTS: G6PD-deficiency is encountered in North America and Western countries previously thought to have a low frequency of the condition. Extreme, sudden neonatal hyperbilirubinemia is due, in the main, to increased hemolysis, an independent risk factor for neurotoxicity. Extreme hyperbilirubinemia may follow apparently resolved neonatal hyperbilirubinemia which had been treated by phototherapy. Female G6PD heterozygotes, previously thought to be unaffected clinically by G6PD-deficiency, while at low risk, may, nevertheless, develop extreme hyperbilirubinemia. Universal neonatal G6PD screening should be aimed towards increasing caretaker awareness and facilitating referral for treatment prior to the onset of bilirubin encephalopathy.

A-318 Validation of umbilical cord blood as an alternate sample type for quantitative in vitro detection of glucose-6-phosphate dehydrogenase in neonates

Abstract Background Detection of glucose-6-phosphate dehydrogenase (G6PD) deficiency provides important information for neonatal clinical management. G6PD newborn screening is recommended using umbilical cord blood specimens in vulnerable patient populations.1 Also, cord blood is used by many clinicians instead of peripheral blood for neonatal screening of G6PD.2 Use of cord blood is a modification to the FDA-approved Pointe Scientific G6PD kinetic-340 nm assay. The aim of this study was to validate cord blood as an alternate specimen type for the Pointe Scientific G6PD assay. Methods Hemoglobin (Hgb) results are from Sysmex XN 9100™ analyzers that use SLS methodology with photometric detection. G6PD results are from Roche cobas® c502 analyzers with Pointe Scientific kinetic method and spectrophotometric detection of activity, expressed as U/g Hgb. Neonatal blood specimens were obtained as paired samples from heel sticks and umbilical cord collected in EDTA lavender top tubes. Accuracy acceptance criteria was defined as Deming regression slope between 0.90 and 1.10, r-value of >0.90 and bias ±15% and mixing study recovery of ±10%. Precision (intra-assay and inter-assay), reportable range and linearity, carryover, and stability were established using cord blood samples or control materials sourced from Thermo Fisher Scientific or Sysmex. Reference intervals3, analytical sensitivity, specificity, and clinical validity were transferred to cord blood due to comparability with whole blood FDA-approved method. EP Evaluator software by Data Innovations® was used for calculations. Results Direct comparison of G6PD results (U/g Hgb) from 125 paired samples yielded a 0.9025 correlation coefficient, 1.024 Deming slope, and -0.25% bias. Mixing and recovery of admixed samples gave % recoveries of 102, 103, 101, 102, 100, and 100 for G6PD (U/g Hgb), and 102, 102, 101, 104, 99, and 105 for Hgb (g/dL). Intra-assay precision results were 2.4, 0.6, 0.8, 0.5, 0.4 % CV for G6PD and Hgb, respectively. Inter-assay precision results were 3.1, 3.3, 0.7, 0.7, 0.5 % CV for G6PD and Hgb, respectively. Reportable range and linearity evaluation resulted in a maximum deviation from target recovery of 4%, and a slope of 0.979 for a range of 50 - 2740 U/L, and reportable range for Hgb was confirmed as 0.1 - 26.0 g/dL using controls (1% maximum deviation and 0.991 slope). Carryover was -5.8 (mean concentration) for G6PD and 0% for Hgb after testing 21 replicates of pooled high and low samples in a defined order. Testing 3 samples in 3 replicates at each defined time interval defined stability as 1 week refrigerated or 72 hours room temperature for G6PD, and 3 days refrigerated or 1 day room temperature for Hgb. Conclusions Regression statistics and mixing-recovery studies demonstrated accuracy for detecting G6PD (U/g Hgb) and Hgb (g/dL) from EDTA cord blood. Additional performance characteristics were transferrable for this specimen type from the FDA-approved method for whole blood. Umbilical cord blood is an acceptable alternate specimen type for quantitative detection of G6PD (U/g Hgb) using Pointe Scientific with Sysmex XN-9100™ and Roche cobas® c502 instrumentation.

Glucose-6-phosphate dehydrogenase deficiency detection using fluorocytometric assay: Evaluation after 1 year of clinical implementation.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common enzymopathy that affects red blood cells (RBCs) and renders them susceptible to oxidative stress. G6PD deficiency can cause hemolytic anemia, especially after exposure to certain drugs or infections. The diagnosis of G6PD deficiency is usually based on spectrophotometric measurement of enzyme activity, but this method has limitations in heterozygous females and in patients with other hematological disorders. In this study, we evaluated the use of flow cytometry as an alternative method for detecting G6PD deficiency in 514 samples (265 females and 249 males) from a clinical laboratory. We compared the results of flow cytometry with those of spectrophotometry and molecular analysis, and assessed the performance of flow cytometry in different subgroups of patients. We found that flow cytometry was able to identify G6PD deficiency in most cases, with high sensitivity and specificity. Flow cytometry also allowed the quantification of the percentage of G6PD-deficient RBCs, which varied among heterozygous females due to X-chromosome inactivation. Moreover, flow cytometry detected several cases of G6PD deficiency that were missed by spectrophotometry, especially in heterozygous females with normal or subnormal enzyme activity. However, flow cytometry also showed some false negative results, mainly in patients with sickle cell disease. Therefore, flow cytometry is a reliable and efficient tool for screening G6PD deficiency, but some precautions should be taken in interpreting the results in patients with other hematological conditions.

Rate of glucose-6-phosphate dehydrogenase deficiency in neonatal indirect hyperbilirubinemia at a private tertiary centre.

To investigate the rate of hospitalized neonates with glucose-6-phosphate dehydrogenase (G6PD) deficiency presented with indirect hyperbilirubinemia at a private tertiary center in Al-Ahsa, Saudi Arabia, over 4 years and to compare the characteristics of G6PD-deficient and normal neonates admitted for indirect hyperbilirubinemia. The retrospective case control study was carried out at Almoosa Specialist Hospital, Al-Ahsa, Saudi Arabia. Data were collected from Yassasi Medical System from 2018-2021 and finalized in 2024. The study included 2 groups: G6PD-normal and G6PD-deficient neonates with indirect hyperbilirubinemia not having recognizable triggers of hemolysis. The analysis focused on serum bilirubin levels, direct bilirubin levels, hematocrit levels, hemoglobin levels, reticulocyte percentage, G6PD levels, duration of phototherapy, and the need for exchange transfusion. The study enrolled 3200 neonates with hyperbilirubinemia, of whom 274 met inclusion criteria. A total of 103 (37.6%) neonates were G6PD-deficient, with 77 (74.8%) being male and 26 (25.2%) female. Glucose-6-phosphate dehydrogenase-deficient neonates exhibited significantly higher initial total bilirubin levels and earlier sampling times. There was no significant correlation between G6PD deficiency and hematocrit or hemoglobin levels in hyperbilirubinemic neonates, but 4 neonates required exchange transfusion, demonstrating statistical significance (p=0.009). High rate of G6PD deficiency in neonates with indirect hyperbilirubinemia, requiring close monitoring to prevent exchange transfusions, with no significant differences in hematocrit or hemoglobin levels.

Mandatory role of endoplasmic reticulum in preserving NADPH regeneration in starved MDA-MB-231 breast cancer cells

Cancer growth requires high amount of nicotinamide adenine dinucleotide phosphate (NADPH) to feed the anabolic reactions and preserve the redox balance. NADPH level is largely preserved by the oxidative arm of the pentose phosphate pathway (PPP). Here, we show that prolonged glucose deprivation of triple negative breast cancer MDA-MB-231 cells decreases proliferation rate, promotes hexose funneling to glycolysis hampering the PPP. The impairment in PPP activity and the consequent NADPH depletion are partially counterbalanced by enhancing the malic enzyme-1 catalyzed conversion of glutamine-derived malate to pyruvate. However, the use of these glucose-independent carbons implies the integrity of the two PPPs represented in all eukaryotic cells, i.e., the well-recognized cytosolic PPP, triggered by glucose-6-phosphate dehydrogenase (G6PD) and its reticular counterpart, triggered by hexose-6P-dehydrogenase (H6PD). This evidence configures the reticular PPP as a mandatory player in the regeneration of NADPH reductive power by cancer cells.

Methaemoglobin as a surrogate marker of primaquine antihypnozoite activity in Plasmodium vivax malaria: A systematic review and individual patient data meta-analysis.

The 8-aminoquinolines, primaquine and tafenoquine, are the only available drugs for the radical cure of Plasmodium vivax hypnozoites. Previous evidence suggests that there is dose-dependent 8-aminoquinoline induced methaemoglobinaemia and that higher methaemoglobin concentrations are associated with a lower risk of P. vivax recurrence. We undertook a systematic review and individual patient data meta-analysis to examine the utility of methaemoglobin as a population-level surrogate endpoint for 8-aminoquinoline antihypnozoite activity to prevent P. vivax recurrence. We conducted a systematic search of Medline, Embase, Web of Science, and the Cochrane Library, from 1 January 2000 to 29 September 2022, inclusive, of prospective clinical efficacy studies of acute, uncomplicated P. vivax malaria mono-infections treated with radical curative doses of primaquine. The day 7 methaemoglobin concentration was the primary surrogate outcome of interest. The primary clinical outcome was the time to first P. vivax recurrence between day 7 and day 120 after enrolment. We used multivariable Cox proportional-hazards regression with site random-effects to characterise the time to first recurrence as a function of the day 7 methaemoglobin percentage (log base 2 transformed), adjusted for the partner schizonticidal drug, the primaquine regimen duration as a proxy for the total primaquine dose (mg base/kg), the daily primaquine dose (mg/kg), and other factors. The systematic review protocol was registered with PROSPERO (CRD42023345956). We identified 219 P. vivax efficacy studies, of which 8 provided relevant individual-level data from patients treated with primaquine; all were randomised, parallel arm clinical trials assessed as having low or moderate risk of bias. In the primary analysis data set, there were 1,747 patients with normal glucose-6-phosphate dehydrogenase (G6PD) activity enrolled from 24 study sites across 8 different countries (Indonesia, Brazil, Vietnam, Thailand, Peru, Colombia, Ethiopia, and India). We observed an increasing dose-response relationship between the daily weight-adjusted primaquine dose and day 7 methaemoglobin level. For a given primaquine dose regimen, an observed doubling in day 7 methaemoglobin percentage was associated with an estimated 30% reduction in the risk of P. vivax recurrence (adjusted hazard ratio = 0.70; 95% confidence interval [CI] [0.57, 0.86]; p = 0.0005). These pooled estimates were largely consistent across the study sites. Using day 7 methaemoglobin as a surrogate endpoint for recurrence would reduce required sample sizes by approximately 40%. Study limitations include the inability to distinguish between recrudescence, reinfection, and relapse in P. vivax recurrences. For a given primaquine regimen, higher methaemoglobin on day 7 was associated with a reduced risk of P. vivax recurrence. Under our proposed causal model, this justifies the use of methaemoglobin as a population-level surrogate endpoint for primaquine antihypnozoite activity in patients with P. vivax malaria who have normal G6PD activity.

G6pdN126D Variant Increases the Risk of Developing VEGFR (Vascular Endothelial Growth Factor Receptor) Blocker-Induced Pulmonary Vascular Disease.

G6PD (glucose-6-phosphate-dehydrogenase) is a key enzyme in the glycolytic pathway and has been implicated in the pathogenesis of cancer and pulmonary hypertension-associated vascular remodeling. Here, we investigated the role of an X-linked G6pd mutation (N126D polymorphism), which is known to increase the risk of cardiovascular disease in individuals from sub-Saharan Africa and many others with African ancestry, in the pathogenesis of pulmonary hypertension induced by a vascular endothelial cell growth factor receptor blocker used for treating cancer. CRISPR-Cas9 genome editing was used to generate the G6pd variant (N126D; G6pdN126D) in rats. A single dose of the vascular endothelial cell growth factor receptor blocker sugen-5416 (SU; 20 mg/kg in DMSO), which is currently in a Phase 2/3 clinical trial for cancer treatment, was subcutaneously injected into G6pdN126D rats and their wild-type littermates. After 8 weeks of normoxic conditions, right ventricular pressure and hypertrophy, pulmonary artery remodeling, the metabolic profile, and cytokine expression were assessed. Right ventricular pressure and pulmonary arterial wall thickness were increased in G6PDN126D+SU/normoxic rats. Simultaneously, levels of oxidized glutathione, inositol triphosphate, and intracellular Ca2+ were increased in the lungs of G6PDN126D+SU/normoxic rats, whereas nitric oxide was decreased. Also increased in G6PDN126D+SU/normoxic rats were pulmonary levels of plasminogen activator inhibitor-1, thrombin-antithrombin complex, and expression of proinflammatory cytokines CCL3 (chemokine [C-C motif] ligand), CCL5, and CCL7. Our results suggest G6PDN126D increases inositol triphosphate-Ca2+ signaling, inflammation, thrombosis, and hypertrophic pulmonary artery remodeling in SU-treated rats. This suggests an increased risk of vascular endothelial cell growth factor receptor blocker-induced pulmonary hypertension in those carrying this G6PD variant.

Ternary structure of Plasmodium vivaxN-myristoyltransferase with myristoyl-CoA and inhibitor IMP-0001173.

Plasmodium vivax is a major cause of malaria, which poses an increased health burden on approximately one third of the world's population due to climate change. Primaquine, the preferred treatment for P. vivax malaria, is contraindicated in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, a common genetic cause of hemolytic anemia, that affects ∼2.5% of the world's population and ∼8% of the population in areas of the world where P. vivax malaria is endemic. The Seattle Structural Genomics Center for Infectious Disease (SSGCID) conducted a structure-function analysis of P.vivax N-myristoyltransferase (PvNMT) as part of efforts to develop alternative malaria drugs. PvNMT catalyzes the attachment of myristate to the N-terminal glycine of many proteins, and this critical post-translational modification is required for the survival of P. vivax. The first step is the formation of aPvNMT-myristoyl-CoA binary complex that can bind to peptides. Understanding how inhibitors prevent protein binding will facilitate the development of PvNMT as a viable drug target. NMTs are secreted in all life stages of malarial parasites, making them attractive targets, unlike current antimalarials that are only effective during the plasmodial erythrocytic stages. The 2.3 Å resolution crystal structure of the ternary complex of PvNMT with myristoyl-CoA and a novel inhibitor is reported. One asymmetric unit contains two monomers. The structure reveals notable differences between the PvNMT and human enzymes and similarities to other plasmodial NMTs that can be exploited to develop new antimalarials.