Lithium Aspartate for Long COVID Fatigue and Cognitive Dysfunction: A Randomized Clinical Trial.

Importance: Neurologic post-COVID-19 condition (PCC), or long COVID, symptoms of fatigue and cognitive dysfunction continue to affect millions of people who have been infected with SARS-CoV-2. There currently are no effective evidence-based therapies available for treating neurologic PCC. Objective: To assess the effects of lithium aspartate therapy on PCC fatigue and cognitive dysfunction. Design, Setting, and Participants: A randomized, double-blind, placebo-controlled trial (RCT) enrolling participants in a neurology clinic from November 28, 2022, to June 29, 2023, with 3 weeks of follow-up, was conducted. Subsequently, an open-label lithium dose-finding study with 6 weeks of follow-up was performed among the same participants enrolled in the RCT. Eligible individuals needed to report new, bothersome fatigue or cognitive dysfunction persisting for more than 4 weeks after a self-reported positive test for COVID-19, Fatigue Severity Scale-7 (FSS-7) or Brain Fog Severity Scale (BFSS) score of 28 or greater, Beck Depression Inventory-II score less than 24, and no history of a condition known to cause fatigue or cognitive dysfunction. All participants in the RCT were eligible for the dose-finding study, except for those who responded to the placebo. Intention-to-treat analysis was used. Intervention: Lithium aspartate, 10 to 15 mg/d, or identically appearing placebo for 3 weeks followed by open-label lithium aspartate, 10 to 15 mg/d, for 2 weeks. In the subsequent dose-finding study, open-label lithium aspartate dosages up to 45 mg/d for 6 weeks were given. Main Outcomes and Measures: Change in sum of FSS-7 and BFSS scores. The scores for each measure range from 7 to 49, with higher scores indicating more severe symptoms. Secondary outcomes included changes from baseline in the scores of additional questionnaires. Results: Fifty-two participants were enrolled (30 [58%] males; mean [SD] age, 58.54 [14.34] years) and 26 were randomized to treatment with lithium aspartate (10 females) and 26 to placebo (12 female). Two participants assigned to lithium aspartate were lost to follow-up and none withdrew. No adverse events were attributable to lithium therapy. There were no significant intergroup differences for the primary outcome (-3.6; 95% CI, -16.6 to 9.5; P = .59) or any secondary outcomes. Among 3 patients completing a subsequent dose-finding study, open-label lithium aspartate, 40 to 45 mg/d, was associated with numerically greater reductions in fatigue and cognitive dysfunction scores than 15 mg/d, particularly in 2 patients with serum lithium levels of 0.18 and 0.49 mEq/L compared with 1 patient with a level of 0.10 mEq/L. Conclusions and Relevance: In this RCT, therapy with lithium aspartate, 10 to 15 mg/d, was ineffective for neurologic PCC fatigue and cognitive dysfunction. Another RCT is required to assess the potential benefits of higher lithium dosages for treating neurologic PCC. Trial Registration: ClinicalTrials.gov Identifier: NCT05618587 and NCT06108297.

Optimization and validation of echo times of point-resolved spectroscopy for cystathionine detection in gliomas.

BACKGROUND: Cystathionine accumulates selectively in 1p/19q-codeleted gliomas, and can serve as a possible noninvasive biomarker. This study aims to optimize the echo time (TE) of point-resolved spectroscopy (PRESS) for cystathionine detection in gliomas, and evaluate the diagnostic accuracy of PRESS for 1p/19q-codeletion identification. METHODS: The TE of PRESS was optimized with numerical and phantom analysis to better resolve cystathionine from the overlapping aspartate multiplets. The optimized and 97 ms TE PRESS were then applied to 84 prospectively enrolled patients suspected of glioma or glioma recurrence to examine the influence of aspartate on cystathionine quantification by fitting the spectra with and without aspartate. The diagnostic performance of PRESS for 1p/19q-codeleted gliomas were assessed. RESULTS: The TE of PRESS was optimized as (TE1, TE2) = (17 ms, 28 ms). The spectral pattern of cystathionine and aspartate were consistent between calculation and phantom. The mean concentrations of cystathionine in vivo fitting without aspartate were significantly higher than those fitting with full basis-set for 97 ms TE PRESS (1.97 ± 2.01 mM vs. 1.55 ± 1.95 mM, p < 0.01), but not significantly different for 45 ms method (0.801 ± 1.217 mM and 0.796 ± 1.217 mM, p = 0.494). The cystathionine concentrations of 45 ms approach was better correlated with those of edited MRS than 97 ms counterparts (r = 0.68 vs. 0.49, both p < 0.01). The sensitivity and specificity for discriminating 1p/19q-codeleted gliomas were 66.7% and 73.7% for 45 ms method, and 44.4% and 52.5% for 97 ms method, respectively. CONCLUSION: The 45 ms TE PRESS yields more precise cystathionine estimates than the 97 ms method, and is anticipated to facilitate noninvasive diagnosis of 1p/19q-codeleted gliomas, and treatment response monitoring in those patients. Medium diagnostic performance of PRESS for 1p/19q-codeleted gliomas were observed, and warrants further investigations.

Strategic Design of Tryptophan-Aspartic Acid-Containing Peptide Inhibitors Using Coronin 1 as a Template: Inhibition of Fusion by Enhancing Acyl Chain Order.

Enveloped viruses enter the host cell by fusing at the cell membrane or entering the cell via endocytosis and fusing at the endosome. Conventional inhibitors target the viral fusion protein to inactivate it for inducing fusion. These target-specific vis-à-vis virus-specific inhibitors fail to display their inhibitory efficacy against emerging and remerging viral infections. This necessitates the need to develop broad-spectrum entry inhibitors that are effective irrespective of the virus. Using a broad range of targeting techniques, the fusion inhibitors can modify the physical characteristics of the viral membrane, making it less prone to fusion. We have previously shown that two tryptophan-aspartic acid (WD)-containing hydrophobic peptides, TG-23 and GG-21, from coronin 1, a phagosomal protein, inhibit membrane fusion by modulating membrane organization and dynamics. In the present work, we designed two WD-containing hydrophilic peptides, QG-22 and AG-22, using coronin 1 as a template and evaluated their fusion inhibitory efficacies in the absence and presence of membrane cholesterol. Our results demonstrate that QG-22 and AG-22 inhibit membrane fusion irrespective of the concentration of membrane cholesterol. Our measurements of depth-dependent membrane organization and dynamics reveal that they impede fusion by enhancing the acyl chain order. Overall, our results validate the hypothesis of designing fusion inhibitors by modulating the membrane's physical properties. In addition, it demonstrates that chain hydrophobicity might not be a critical determinant for the development of peptide-based fusion inhibitors.

On the Stabilizing Effect of Aspartate and Glutamate and Its Counteraction by Common Denaturants.

By performing differential scanning calorimetry(DSC) measurements on RNase A, we studied the stabilization provided by the addition of potassium aspartate(KAsp) or potassium glutamate (KGlu) and found that it leads to a significant increase in the denaturation temperature of the protein. The stabilization proves to be mainly entropic in origin. A counteraction of the stabilization provided by KAsp or KGlu is obtained by adding common denaturants such as urea, guanidinium chloride, or guanidinium thiocyanate. A rationalization of the experimental data is devised on the basis of a theoretical approach developed by one of the authors. The main contribution to the conformational stability of globular proteins comes from the gain in translational entropy of water and co-solute ions and/or molecules for the decrease in solvent-excluded volume associated with polypeptide folding (i.e., there is a large decrease in solvent-accessible surface area). The magnitude of this entropic contribution increases with the number density and volume packing density of the solution. The two destabilizing contributions come from the conformational entropy of the chain, which should not depend significantly on the presence of co-solutes, and from the direct energetic interactions between co-solutes and the protein surface in both the native and denatured states. It is the magnitude of the latter that discriminates between stabilizing and destabilizing agents.

Development of a µPAD for the point-of-care testing of serum glutamic oxaloacetic transaminase (SGOT).

A wax-patterned paper analytical device (µPAD) has been developed for point-of-care colourimetric testing of serum glutamic oxaloacetic transaminase (SGOT). The detection method was based on the transamination reaction of aspartate with α-ketoglutarate, leading to the formation of oxaloacetate which reacts with the reagent Fast Blue BB salt and forms a cavern pink colour. The intensity of the cavern pink colour grows as the concentration of SGOT increases. UV-visible spectroscopy was utilized to optimize reaction conditions, and the optimized reagents were dropped onto the wax-patterned paper. The coloured PADs, after the addition of SGOT, have been photographed, and a colour band has been generated to correlate the SGOT concentration visually. The images were used to calculate the intensity values using ImageJ software, which inturn was used to calculate the SGOT concentration. The PADs were also tested with serum samples, and SGOT spiked serum samples. The PAD could detect the SGOT concentration ranging from 5 to 200 U/L. The analysis yielded highly accurate results with less than 6% relative error compared to the clinical sample. This colourimetric test demonstrated exceptional selectivity in the presence of other biomolecules in the blood serum, with a detection limit of 2.77 U/L and a limit of quantification of 9.25 U/L. Additionally, a plasma separation membrane was integrated with the PAD to directly test SGOT from finger-prick blood samples.

Changes in the medial prefrontal cortex metabolites after 6 months of medication therapy for patients with bipolar disorder: A 1H-MRS study.

AIMS: The study aimed to assess brain metabolite differences in the medial prefrontal cortex (mPFC) between acute and euthymic episodes of bipolar disorder (BD) with both mania and depression over a 6-month medication treatment period. METHODS: We utilized 1H-MRS technology to assess the metabolite levels in 53 individuals with BD (32 in depressive phase, 21 in manic phase) and 34 healthy controls (HCs) at baseline. After 6 months of medication treatment, 40 subjects underwent a follow-up scan in euthymic state. Metabolite levels, including N-acetyl aspartate (NAA), glutamate (Glu), and Glutamine (Gln), were measured in the mPFC. RESULTS: Patients experiencing depressive and manic episodes exhibited a notable reduction in NAA/Cr + PCr ratios at baseline compared to healthy controls (p = 0.004; p = 0.006) in baseline, compared with HCs. Over the 6-month follow-up period, the manic group displayed a significant decrease in Gln/Cr + PCr compared to the initial acute phase (p = 0.03). No significant alterations were found in depressed group between baseline and follow-up. CONCLUSION: This study suggests that NAA/Cr + PCr ratios and Gln/Cr + PCr ratios in the mPFC may be associated with manic and depressive episodes, implicating that Gln and NAA might be useful biomarkers for distinguishing mood phases in BD and elucidating its mechanisms.

N-acetylaspartate promotes glycolytic-to-oxidative fiber-type switch and resistance to atrophic stimuli in myotubes.

N-acetylaspartate (NAA) is a neuronal metabolite that can be extruded in extracellular fluids and whose blood concentration increases in several neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS). Aspartoacylase (ASPA) is the enzyme responsible for NAA breakdown. It is abundantly expressed in skeletal muscle and most other human tissues, but the role of NAA catabolism in the periphery is largely neglected. Here we demonstrate that NAA treatment of differentiated C2C12 muscle cells increases lipid turnover, mitochondrial biogenesis and oxidative metabolism at the expense of glycolysis. These effects were ascribed to NAA catabolism, as CRISPR/Cas9 ASPA KO cells are insensitive to NAA administration. Moreover, the metabolic switch induced by NAA was associated with an augmented resistance to atrophic stimuli. Consistently with in vitro results, SOD1-G93A ALS mice show an increase in ASPA levels in those muscles undergoing the glycolytic to oxidative switch during the disease course. The impact of NAA on the metabolism and resistance capability of myotubes supports a role for this metabolite in the phenotypical adaptations of skeletal muscle in neuromuscular disorders.

Maternal prenatal immune activation associated with brain tissue microstructure and metabolite concentrations in newborn infants.

Few human studies have assessed the association of prenatal maternal immune activation (MIA) with measures of brain development and psychiatric risk in newborn offspring. Our goal was to identify the effects of MIA during the 2nd and 3rd trimesters of pregnancy on newborn measures of brain metabolite concentrations, tissue microstructure, and motor development. This was a prospective longitudinal cohort study conducted with nulliparous pregnant women who were aged 14 to 19 years and recruited in their 2nd trimester, as well as their children who were followed through 14 months of age. MIA was indexed by maternal interleukin-6 (IL-6) and C-reactive protein (CRP) in both trimesters of pregnancy. Primary outcomes included: (1) newborn brain metabolite concentrations as ratios to creatine (N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr) measured using Magnetic Resonance Spectroscopy; (2) newborn fractional anisotropy and mean diffusivity, measured using Diffusion Tensor Imaging; and (3) indices of motor development, assessed prenatally and postnatally at ages 4- and 14-months. Maternal IL-6 and CRP levels associated significantly with both metabolites in the putamen, thalamus, insula, and the internal capsule. Maternal IL-6 associated significantly with fractional anisotropy in the putamen, caudate, thalamus, insula, and precuneus, and with mean diffusivity in the inferior parietal and middle temporal gyrus. CRP associated significantly with fractional anisotropy in the thalamus, insula, and putamen. Significant associations were found in common regions across imaging modalities, though the direction of associations differed by immune marker. In addition, both maternal IL-6 and CRP (in both trimesters) prenatally associated significantly with offspring motor development at 4- and 14-months of age. The left thalamus mediated effects of IL-6 on postnatal motor development. These findings demonstrate that levels of MIA in mid- to late pregnancy in a generally healthy sample associate with tissue characteristics in newborn brain regions that primarily support motor integration and coordination, as well as behavioral regulation. Those brain effects may contribute to differences in motor development.

Efficacy of aspergillomarasmine A/meropenem combinations with and without avibactam against bacterial strains producing multiple ß-lactamases.

The effectiveness of ß-lactam antibiotics is increasingly threatened by resistant bacteria that harbor hydrolytic ß-lactamase enzymes. Depending on the class of ß-lactamase present, ß-lactam hydrolysis can occur through one of two general molecular mechanisms. Metallo-ß-lactamases (MBLs) require active site Zn2+ ions, whereas serine-ß-lactamases (SBLs) deploy a catalytic serine residue. The result in both cases is drug inactivation via the opening of the ß-lactam warhead of the antibiotic. MBLs confer resistance to most ß-lactams and are non-susceptible to SBL inhibitors, including recently approved diazabicyclooctanes, such as avibactam; consequently, these enzymes represent a growing threat to public health. Aspergillomarasmine A (AMA), a fungal natural product, can rescue the activity of the ß-lactam antibiotic meropenem against MBL-expressing bacterial strains. However, the effectiveness of this ß-lactam/ß-lactamase inhibitor combination against bacteria producing multiple ß-lactamases remains unknown. We systematically investigated the efficacy of AMA/meropenem combination therapy with and without avibactam against 10 Escherichia coli and 10 Klebsiella pneumoniae laboratory strains tandemly expressing single MBL and SBL enzymes. Cell-based assays demonstrated that laboratory strains producing NDM-1 and KPC-2 carbapenemases were resistant to the AMA/meropenem combination but became drug-susceptible upon adding avibactam. We also probed these combinations against 30 clinical isolates expressing multiple ß-lactamases. E. coli, Enterobacter cloacae, and K. pneumoniae clinical isolates were more susceptible to AMA, avibactam, and meropenem than Pseudomonas aeruginosa and Acinetobacter baumannii isolates. Overall, the results demonstrate that a triple combination of AMA/avibactam/meropenem has potential for empirical treatment of infections caused by multiple ß-lactamase-producing bacteria, especially Enterobacterales.

Diffusion magnetic resonance spectroscopy captures microglial reactivity related to gut-derived systemic lipopolysaccharide: A preliminary study.

Neuroinflammation is a key component underlying multiple neurological disorders, yet non-invasive and cost-effective assessment of in vivo neuroinflammatory processes in the central nervous system remains challenging. Diffusion weighted magnetic resonance spectroscopy (dMRS) has shown promise in addressing these challenges by measuring diffusivity properties of different neurometabolites, which can reflect cell-specific morphologies. Prior work has demonstrated dMRS utility in capturing microglial reactivity in the context of lipopolysaccharide (LPS) challenges and serious neurological disorders, detected as changes of microglial metabolite diffusivity properties. However, the extent to which such dMRS metrics are capable of detecting subtler and more nuanced levels of neuroinflammation in populations without overt neuropathology is unknown. Here we examined the relationship between intrinsic, gut-derived levels of systemic LPS and dMRS-based apparent diffusion coefficients (ADC) of choline, creatine, and N-acetylaspartate (NAA) in two brain regions: the thalamus and the corona radiata. Higher plasma LPS concentrations were significantly associated with increased ADC of choline and NAA in the thalamic region, with no such relationships observed in the corona radiata for any of the metabolites examined. As such, dMRS may have the sensitivity to measure microglial reactivity across populations with highly variable levels of neuroinflammation, and holds promising potential for widespread applications in both research and clinical settings.

Aspartate in tumor microenvironment and beyond: Metabolic interactions and therapeutic perspectives.

Aspartate is a proteinogenic non-essential amino acid with several essential functions in proliferating cells. It is mostly produced in a cell autonomous manner from oxalacetate via glutamate oxalacetate transaminases 1 or 2 (GOT1 or GOT2), but in some cases it can also be salvaged from the microenvironment via transporters such as SLC1A3 or by macropinocytosis. In this review we provide an overview of biosynthetic pathways that produce aspartate endogenously during proliferation. We discuss conditions that favor aspartate uptake as well as possible sources of exogenous aspartate in the microenvironment of tumors and bone marrow, where most available data have been generated. We highlight metabolic fates of aspartate, its various functions, and possible approaches to target aspartate metabolism for cancer therapy.

In silico approaches to study the human asparagine synthetase: An insight of the interaction between the enzyme active sites and its substrates.

Cancer is a leading concern and important cause of death worldwide. Cancer is a non-communicable illness defined as uncontrolled division of cells. It can develop into metastatic cancer when tumor cells migrate to other organs. In recent years evidence has emerged that the bioavailability of Asn play a crucial role in cancer metastasis. Asn is a non-essential amino acid formed from an ATP dependent catalyzed reaction by the enzyme asparagine synthetase (ASNS), where Asp and Gln are converted to Asn and Glu, respectively. The human ASNS enzyme consist of 561 amino acids, with a molecular weight of 64 KDa. ASNS governs the activation of transcriptional factors that regulate the process of metastasis. In this work the 3D model of ASNS in E. coli (AS-B) and the human ASNS docked with its different ligands have been used to study the 3D mechanism of the conversion of Asp and Gln to Asn and Glu, in human ASNS. The stability evaluation of the docked complexes was checked by molecular dynamic simulation through the bioinformatic tool Desmond. The binding residues and their interactions can be exploited for the development of inhibitors, as well as for finding new drug molecules against ASNS and prevention of metastatic cancer.

The Increased aspartate levels in transgenic cotton (Gossypium hirsutum L.) lead to improved tolerance against whitefly (Bemisia tabaci, Gennadius).

The whitefly, a polyphagous insect pest feeding on nearly 1328 plant species, is a major threat to global cotton production and incurs up to 50% yield losses in cotton production in Pakistan. We investigated whether increased aspartate in phloem sap imparts whitefly toxicity and protects cotton plants from intense damage. The enzymatic step for aspartate production is carried through aspartate aminotransferase (AAT). In this study, we constitutively overexpressed the Oryza sativa cytoplasmic AAT (OsAAT2) under the CaMV35S promoter in Gossypium hirsutum cv. CIM-482. Real-time PCR analysis of the AAT transcripts revealed a 2.85- to 31.7-fold increase in mRNA levels between the different cotton lines. A substantial increase in the free-amino acid content of the major N-assimilation and transport amino acids (aspartate, glutamate, asparagine, and glutamine) was seen in the phloem sap of the transgenic cotton lines. The bioassay revealed that the two transgenic cotton lines with the highest free aspartate content in the phloem sap exhibited 97 and 94% mortality in the adult whitefly population and a 98 and 96% decline in subsequent nymph populations, respectively. There was also a significant change in the physiological behaviour of the transgenic cotton lines, with an increased net assimilation (A), gaseous exchange (Gs) and rate of transpiration (E). Improved morphological characteristics like plant height, total number of bolls and fiber yield were recorded in transgenic cotton lines. The AAT gene shows promise in mitigating whitefly infestations and enhancing the overall health and yield of cotton plants.

Catalytic Enantioselective Sulfoxidation of Functionalized Thioethers Mediated by Aspartic Acid-Containing Peptides.

A peptide-catalyzed enantioselective oxidation of sulfides to yield pharmaceutically relevant chiral sulfoxides is reported. Experimental evidence suggesting that a hydrogen bond-donating moiety must be present in the substrate to achieve high levels of enantioinduction is supported by computational modeling of transition states. These models also indicate that dual points of contact between the peptidic catalyst and substrate are likely responsible for the formation of one desired sulfoxide in 94:6 er.

New Insights into D-Aspartate Signaling in Testicular Activity.

D-aspartate (D-Asp) is an amino acid found in high concentrations in the testis and pituitary gland. Increasing evidence suggests that D-Asp promotes spermatogenesis by activating testosterone production in the Leydig cells via LH release from the pituitary gland. In vitro studies indicate that D-Asp may also influence steroidogenesis and spermatogenesis through autocrine and paracrine signals. D-Asp enhances StAR and steroidogenic enzyme expressions, facilitating testicular cell proliferation via the GluR/ERK1/2 pathway. Moreover, it supports spermatogenesis by enhancing the mitochondrial function in spermatocytes, aiding in the metabolic shift during meiosis. Enhanced mitochondrial function, along with improved MAM stability and reduced ER stress, has been observed in Leydig and Sertoli cells treated with D-Asp, indicating potential benefits in steroidogenesis and spermatogenesis efficiency. Conversely, D-Asp exerts a notable anti-apoptotic effect in the testis via the AMPAR/AKT pathway, potentially mediated by antioxidant enzyme modulation to mitigate testicular oxidative stress. This review lays the groundwork for future investigations into the molecules promoting spermatogenesis by stimulating endogenous testosterone biosynthesis, with D-amino acids emerging as promising candidates.

Assaying D-Amino Acid in Japanese Sake Using L-Amino Acid Derivatizing Agent.

The D-amino acids of D-alanine, D-glutamic acid, and D-aspartic acid increase tasting evaluation scores of Sake, a Japanese traditional alcohol beverage. Sake is brewed using seed mash for growth of brewing yeast without growth of contaminating microorganisms. Kimoto is brewed using lactic acid bacteria growth to decrease pH. Sake brewed using the Kimoto method also has a rich taste and a higher tasting evaluation score than Sake brewed using the Sokujyo Syubo (Moto) method, which adds lactic acid instead of using lactic acid bacteria growth. D-alanine, D-glutamic acid, and D-aspartic acid in Sake have the function of increasing tasting evaluation scores. They are converted by enzymes in lactic acid bacteria respectively as alanine racemase (EC 5.1.1.1), glutamate racemase (EC 5.1.1.3), and aspartate racemase (EC 5.1.1.13) in Kimoto Mash. Herein, simultaneous assay methods for D-alanine, D-glutamic acid, and D-aspartic acid are explained. Sample solutions adjusted to alkalinity are derivatized by an L-FDLA solution only for L-amino acid. Results demonstrate that, for D-alanine, D-glutamic acid, and D-aspartic acid, this method can assay them easily using no expensive or specialized equipment.

Pro-atherogenic medical conditions are associated with widespread regional brain metabolite abnormalities in those with alcohol use disorder.

AIMS: Widespread brain metabolite abnormalities in those with alcohol use disorder (AUD) were reported in numerous studies, but the effects of the pro-atherogenic conditions of hypertension, type 2 diabetes mellitus, hepatitis C seropositivity, and hyperlipidemia on metabolite levels were not considered. These conditions were associated with brain metabolite abnormalities in those without AUD. We predicted treatment-seeking individuals with AUD and pro-atherogenic conditions (Atherogenic+) demonstrate lower regional metabolite markers of neuronal viability [N-acetylaspartate (NAA)] and cell membrane turnover/synthesis [choline-containing compounds (Cho)], compared with those with AUD without pro-atherogenic conditions (Atherogenic-) and healthy controls (CON). METHODS: Atherogenic+ (n = 59) and Atherogenic- (n = 51) and CON (n = 49) completed a 1.5 T proton magnetic resonance spectroscopic imaging study. Groups were compared on NAA, Cho, total creatine, and myoinositol in cortical gray matter (GM), white matter (WM), and select subcortical regions. RESULTS: Atherogenic+ had lower frontal GM and temporal WM NAA than CON. Atherogenic+ showed lower parietal GM, frontal, parietal and occipital WM and lenticular nuclei NAA level than Atherogenic- and CON. Atherogenic- showed lower frontal GM and WM NAA than CON. Atherogenic+ had lower Cho level than CON in the frontal GM, parietal WM, and thalamus. Atherogenic+ showed lower frontal WM and cerebellar vermis Cho than Atherogenic- and CON. CONCLUSIONS: Findings suggest proatherogenic conditions in those with AUD were associated with increased compromise of neuronal integrity and cell membrane turnover/synthesis. The greater metabolite abnormalities observed in Atherogenic+ may relate to increased oxidative stress-related compromise of neuronal and glial cell structure and/or impaired arterial vasoreactivity/lumen viability.

A low-barrier proton shared between two aspartates acts as a conformational switch that changes the substrate specificity of the ß-lactamase BlaC.

Serine ß-lactamases inactivate ß-lactam antibiotics in a two-step mechanism comprising acylation and deacylation. For the deacylation step, a water molecule is activated by a conserved glutamate residue to release the adduct from the enzyme. The third-generation cephalosporin ceftazidime is a poor substrate for the class A ß-lactamase BlaC from Mycobacterium tuberculosis but it can be hydrolyzed faster when the active site pocket is enlarged, as was reported for mutant BlaC P167S. The conformational change in the Ω-loop of the P167S mutant displaces the conserved glutamate (Glu166), suggesting it is not required for deacylation of the ceftazidime adduct. Here, we report the characterization of wild type BlaC and BlaC E166A at various pH values. The presence of Glu166 strongly enhances activity against nitrocefin but not ceftazidime, indicating it is indeed not required for deacylation of the adduct of the latter substrate. At high pH wild type BlaC was found to exist in two states, one of which converts ceftazidime much faster, resembling the open state previously reported for the BlaC mutant P167S. The pH-dependent switch between the closed and open states is caused by the loss at high pH of a low-barrier hydrogen bond, a proton shared between Asp172 and Asp179. These results illustrate how readily shifts in substrate specificity can occur as a consequence of subtle changes in protein structure.

Constructing an artificial in vitro multi-enzyme cascade pathway to convert glycerol and CO2 into L-aspartic acid.

Developing utilization technologies for biomass resources, exploring their applications in the fields of energy and chemical engineering, holds significant importance for promoting sustainable development and constructing a green, low-carbon society. In this study, we designed a non-natural in vitro multi-enzyme system for converting glycerol and CO2 into L-aspartic acid (L-Asp). The coupled system utilized eight enzymes, including alditol oxidase (ALDO), catalase-peroxidase (CAT), lactaldehyde dehydrogenase (ALDH), glycerate 2-kinase (GK), phosphopyruvate hydratase (PPH), phosphoenolpyruvate carboxylase (PPC), L-aspartate dehydrogenase (ASPD), and polyphosphate kinase (PPK), to convert the raw materials into L-Asp in one-pot coupled with NADH and ATP regeneration. Under optimal reaction conditions, 18.6 mM of L-Asp could be produced within 2.0 h at a total enzyme addition of 4.85 mg/mL, demonstrating the high efficiency and productivity characteristics of the designed system. Our technological application provides new insights and methods for the development of biomass resource utilization technologies.

Neuropathic phenotypes of type 1 diabetes are related to different signatures of magnetic resonance spectroscopy-assessed brain metabolites.

OBJECTIVES: The study aimed to investigate brain metabolites in type 1 diabetes and the associations with disease characteristics. We explored the metabolic profiles predicting different neuropathic phenotypes using multiple linear regression analyses. METHODS: We compared brain metabolites in 55 adults with type 1 diabetes (including painful diabetic peripheral neuropathy (DPN), painless DPN, without DPN) with 20 healthy controls. Proton magnetic resonance spectroscopy measurements (N-acetylaspartate (NAA), glutamate (glu), myo-inositol (mI), and glycerophosphocholine (GPC) were obtained in ratios to creatine (cre)) from the parietal region, anterior cingulate cortex and thalamus. RESULTS: The overall diabetes group revealed decreased parietal NAA/cre compared to healthy controls (1.41 ± 0.12 vs. 1.55 ± 0.13,p < 0.001) and increased mI/cre (parietal: 0.62 ± 0.08 vs. 0.57 ± 0.07,p = 0.025, cingulate: 0.65 ± 0.08 vs. 0.60 ± 0.08,p = 0.033). Reduced NAA/cre was associated with more severe DPN (all p ≤ 0.04) whereas increased mI/cre was associated with higher hemoglobin A1c (HbA1c) (p = 0.02). Diabetes was predicted from decreased parietal NAA/cre, increased parietal ml/cre, and decreased thalamic glu/cre. DPN was predicted from decreased parietal NAA/cre and increased GPC/cre. Painful DPN was predicted from increased parietal GPC/cre and thalamic glu/cre. CONCLUSIONS: Specific metabolic brain profiles were linked to the different phenotypes of diabetes, DPN and painful DPN. SIGNIFICANCE: Assessment of metabolic profiles could be relevant for detailed understanding of central neuropathy in diabetes.