GDF-15 Levels and Other Laboratory Findings as Predictors of COVID-19 Severity and Mortality: A Pilot Study.

Growth differentiation factor 15 (GDF-15) is a stress-induced cytokine associated with acute and chronic inflammatory states. This prospective observational study aimed to investigate the prognostic roles of GDF-15 and routine clinical laboratory parameters in COVID-19 patients. Upon the admission of 95 adult hospitalized COVID-19 patients in Croatia, blood analysis was performed, and medical data were collected. The patients were categorized based on survival, ICU admission, and hospitalization duration. Logistic regression and ROC curve methods were employed for the statistical analysis. Logistic regression revealed two independent predictors of negative outcomes: CURB-65 score (OR = 2.55) and LDH (OR = 1.005); one predictor of ICU admission: LDH (OR = 1.004); and one predictor of prolonged hospitalization: the need for a high-flow nasal cannula (HFNC) upon admission (OR = 4.75). The ROC curve showed diagnostic indicators of negative outcomes: age, CURB-65 score, LDH, and GDF-15. The largest area under the curve (AUC = 0.767, specificity = 65.6, sensitivity = 83.9) was represented by GDF-15, with a cutoff value of 3528 pg/mL. For ICU admission, significant diagnostic indicators were LDH, CRP, and IL-6. Significant diagnostic indicators of prolonged hospitalization were CK, GGT, and oxygenation with an HFNC upon admission. This study reaffirms the significance of the commonly used laboratory parameters and clinical scores in evaluating COVID-19. Additionally, it introduces the potential for a new diagnostic approach and research concerning GDF-15 levels in this widespread disease.

The unusual kinetics of lactate dehydrogenase of Schistosoma mansoni and their role in the rapid metabolic switch after penetration of the mammalian host.

Lactate dehydrogenase (LDH) from Schistosoma mansoni has peculiar properties for a eukaryotic LDH. Schistosomal LDH (SmLDH) isolated from schistosomes, and the recombinantly expressed protein, are strongly inhibited by ATP, which is neutralized by fructose-1,6-bisphosphate (FBP). In the conserved FBP/anion binding site we identified two residues in SmLDH (Val187 and Tyr190) that differ from the conserved residues in LDHs of other eukaryotes, but are identical to conserved residues in FBP-sensitive prokaryotic LDHs. Three-dimensional (3D) models were generated to compare the structure of SmLDH with other LDHs. These models indicated that residues Val187, and especially Tyr190, play a crucial role in the interaction of FBP with the anion pocket of SmLDH. These 3D models of SmLDH are also consistent with a competitive model of SmLDH inhibition in which ATP (inhibitor) and FBP (activator) compete for binding in a well-defined anion pocket. The model of bound ATP predicts a distortion of the nearby key catalytic residue His195, resulting in enzyme inhibition. To investigate a possible physiological role of this allosteric regulation of LDH in schistosomes we made a kinetic model in which the allosteric regulation of the glycolytic enzymes can be varied. The model showed that inhibition of LDH by ATP prevents fermentation to lactate in the free-living stages in water and ensures complete oxidation via the Krebs cycle of the endogenous glycogen reserves. This mechanism of allosteric inhibition by ATP prevents the untimely depletion of these glycogen reserves, the only fuel of the free-living cercariae. Neutralization by FBP of this ATP inhibition of LDH prevents accumulation of glycolytic intermediates when S. mansoni schistosomula are confronted with the sudden large increase in glucose availability upon penetration of the final host. It appears that the LDH of S. mansoni is special and well suited to deal with the variations in glucose availability the parasite encounters during its life cycle.

Cationic polyelectrolytes prevent the aggregation of l-lactate dehydrogenase under unstable conditions.

Unstructured biological macromolecules have attracted attention as protein aggregation inhibitors in living cells. Some are characterized by their free structural configuration, highly charged, and water-soluble. However, the importance of these properties in inhibiting protein aggregation remains unclear. In this study, we investigated the effect of charged poly (amino acids), which mimic these properties, on aggregation of l-lactate dehydrogenase (LDH) and compared their effects to monomeric amino acids and folded proteins. LDH was stable and active at a neutral pH (~7) but formed inactive aggregates at acidic pH (< 6). Adding cationic polyelectrolytes of poly-l-lysine and poly-l-arginine suppressed the acid-induced aggregation and inactivation of LDH under acidic pH values. Adding monomeric amino acids and cationic folded proteins also prevented LDH aggregation but with lower efficacy than cationic polyelectrolytes. These results indicate that unstructured polyelectrolytes effectively stabilize unstable enzymes because they interact flexibly and multivalently with them. Our findings provide a simple method for stabilizing enzymes under unstable conditions.

Lactate Dehydrogenase Superfamily in Rice and Arabidopsis: Understanding the Molecular Evolution and Structural Diversity.

Lactate/malate dehydrogenases (Ldh/Maldh) are ubiquitous enzymes involved in the central metabolic pathway of plants and animals. The role of malate dehydrogenases in the plant system is very well documented. However, the role of its homolog L-lactate dehydrogenases still remains elusive. Though its occurrence is experimentally proven in a few plant species, not much is known about its role in rice. Therefore, a comprehensive genome-wide in silico investigation was carried out to identify all Ldh genes in model plants, rice and Arabidopsis, which revealed Ldh to be a multigene family encoding multiple proteins. Publicly available data suggest its role in a wide range of abiotic stresses such as anoxia, salinity, heat, submergence, cold and heavy metal stress, as also confirmed by our qRT-PCR analysis, especially in salinity and heavy metal mediated stresses. A detailed protein modelling and docking analysis using Schrodinger Suite reveals the presence of three putatively functional L-lactate dehydrogenases in rice, namely OsLdh3, OsLdh7 and OsLdh9. The analysis also highlights the important role of Ser-219, Gly-220 and His-251 in the active site geometry of OsLdh3, OsLdh7 and OsLdh9, respectively. In fact, these three genes have also been found to be highly upregulated under salinity, hypoxia and heavy metal mediated stresses in rice.

Thermodynamic and kinetic analysis on oligomeric protein dissociation using high-pressure native PAGE velocity method.

High pressure is known to dissociate several oligomeric proteins, and regarded as an important tool to shift the oligomerization equilibrium. Native polyacrylamide gel electrophoresis (native PAGE) at high pressure can characterize the dissociates and clearly discriminate the aggregates. However, a band smearing of migration profiles often hinders more detailed analyses (Miwa et al., High Pressure Res. (2019) 39, 218-224). In this paper, we focused on the band smearing dependent on the migration velocity so as to extract both thermodynamic and kinetic parameters. We systematically perturbed the migration velocity by changing the gel concentration and carried out numerical analysis for a series of the migration profiles based on a simple dissociation reaction scheme with limited thermodynamic and kinetic parameters. Then, complete volumetric properties on oligomerization process can be available. We term the present analysis method as a high-pressure native PAGE velocity method. We also report the application of this method to revisit the pressure dissociation of tetrameric lactate dehydrogenase (LDH) from pig heart.

Creatine supplementation for post-exercise muscle damage / Suplementação com creatina para danos musculares pós-exercício / Suplementación con creatina para daños musculares después del ejercicio

ABSTRACT Introduction: Exercise-induced muscle damage (EIMD) can occur from recent or unusual physical activity, leading to a temporary reduction in muscle function. And increased pain. Several articles indicate the positive impacts of creatine on EIMD. Objective: Evaluate the impact of creatine on EIMD. Methods: Online searches were performed in Scopus, Embase, Medline and Google scholar until March 2022. Results: Thirteen studies met the inclusion criteria. To assess the quality of the studies, the Cochrane collaboration system was used for risk and bias analysis. Due to the high heterogeneity of interventions and studies designed, a meta-analysis was not performed. The current paper reveals that creatine intake is preferable to inactive recovery and only a rest period between several harmful and exhausting physical activities. Conclusion: Benefits were attenuated in EIMD markers that reduce muscle operation and muscle strength loss after exercise. Level of evidence II; Therapeutic studies - Manuscript review.

RESUMO Introdução: O dano muscular induzido pelo exercício (EIMD) pode acontecer por atividade física recente ou não habitual e leva a uma redução temporária da função muscular. e aumento da dor. Vários artigos indicam impactos positivos da creatina sobre a EIMD. Objetivo: Avaliar o impacto da creatina sobre a EIMD. Métodos: Foram feitas pesquisas eletrônicas em Scopus, Embase, Medline e Google scholar até março de 2022. Resultados: Treze estudos preencheram os critérios de inclusão. Para avaliar a qualidade dos estudos, o sistema de colaboração Cochrane foi utilizado na análise de risco e viés. Devido à alta heterogeneidade de intervenções e estudos desenhados, a meta-análise não foi realizada. As informações do documento atual revelam que a ingestão de creatina é preferível a uma recuperação inativa e apenas um período de repouso entre diversas atividades físicas prejudiciais e exaustivas. Conclusão: Os benefícios evidenciaram-se atenuados nos marcadores EIMD que reduzem a operação muscular e a perda de força muscular após os exercícios. Nível de evidência II; Estudos terapêuticos - Revisão de manuscritos.

RESUMEN Introducción: el daño muscular inducido por el ejercicio (EIMD) puede producirse por una actividad física reciente o inusual y provoca una reducción temporal de la función muscular y un aumento del dolor. Varios artículos indican impactos positivos de la creatina en la EIMD. Objetivo: Evaluar el impacto de la creatina en la EIMD. Métodos: Se realizaron búsquedas electrónicas en Scopus, Embase, Medline y Google scholar hasta marzo de 2022. Resultados: Trece estudios cumplieron los criterios de inclusión. Para evaluar la calidad de los estudios, se utilizó el sistema de colaboración Cochrane para el análisis de riesgos y sesgos. Debido a la gran heterogeneidad de las intervenciones y de los estudios diseñados, no se realizó un metanálisis. La información del presente documento revela que la ingesta de creatina es preferible a una recuperación inactiva y sólo un período de descanso entre varias actividades físicas perjudiciales y agotadoras. Conclusión: Los beneficios se mostraron atenuados en los marcadores EIMD que reducen el funcionamiento muscular y la pérdida de fuerza muscular después del ejercicio. Nivel de evidencia II; Estudios terapéuticos - Revisión de manuscritos.

Clinical efficacy of ateplase combined with heparin in the treatment of acute moderate- and high-risk pulmonary thromboembolism and its effects on arterial blood gas analysis and myocardial enzyme level / 中国基层医药

Objective:To investigate the clinical efficacy of alteplase combined with heparin in the treatment of acute moderate- and high-risk pulmonary thromboembolism and its effects on arterial blood gas analysis and myocardial enzyme level.Methods:Seventy-eight patients with acute moderate- and high-risk pulmonary thromboembolism who received treatment in Dongyang People's Hospital from January 2015 to January 2022 were retrospectively included in this study. They were divided into observation ( n = 39) and control ( n = 39) groups according to different treatment methods. The control group was treated with heparin, while the observation group was treated with alteplase based on heparin. All patients were treated for 7 days. Clinical efficacy as well as arterial blood gas analysis, myocardial enzymes, pulmonary artery pressure, and tricuspid annular plane systolic excursion pre- and post-treatment were compared between the two groups. Results:The total response rate in the observation group was significantly higher than that in the control group (94.87% vs. 76.92%, χ2 = 5.18, P < 0.05). After treatment, the partial pressure of carbon dioxide in the observation group was significantly lower than that in the control group [(36.24 ± 5.12) mmHg vs. (44.25 ± 3.78) mmHg, 1 mmHg = 0.133 kPa, t = 7.86, P < 0.05]. After treatment, the partial pressure of oxygen in the observation group was significantly higher than that in the control group [(78.82 ± 5.1) mmHg vs. (71.23 ± 4.89) mmHg, t = 6.66, P < 0.05]. After treatment, lactate dehydrogenase, creatine kinase, and creatine kinase isoenzyme in the observation group were (107.42 ± 15.45) U/L, (37.21 ± 10.84) U/L, and (12.28 ± 3.54) U/L, respectively, which were significantly lower than (189.94 ± 21.20) U/L, (65.42 ± 6.57) U/L, and (19.29 ± 3.08) U/L in the control group ( t = 19.64, 13.89, 9.33, all P < 0.001). After treatment, the pulmonary arterial pressure in the observation group was significantly lower than that in the control group [(32.24 ± 3.86) mmHg vs. (37.79 ± 5.17) mmHg, t = 5.37, P < 0.001]. Tricuspid annular plane systolic excursion in the observation group was significantly higher than that in the control group [(14.07 ± 1.27) mm vs. (12.63 ± 1.16) mm, t = 5.22, P < 0.001]. Conclusion:Ateplase combined with heparin has an obvious effect on acute moderate- and high-risk pulmonary thromboembolism. It can improve arterial blood gas analysis and reduce myocardial enzyme levels.

A functionally uncharacterized type-2 malate/L-lactate dehydrogenase family protein from Thermus thermophilus HB8 catalyzes stereospecific reduction of 2-keto-3-deoxy-D-gluconate.

2-Keto-3-deoxy- D-gluconate (KDG) is an important intermediate found in various sugars, sugar acids and polysaccharide catabolic pathways. Here, we report that a functionally uncharacterized type-2 malate/L-lactate dehydrogenase family protein (TTHB078) from Thermus thermophilus HB8 catalyzes a novel reaction, NAD(P)H-dependent reductase activity on KDG. This enzyme, designated KdgG, utilizes both NADH and NADPH as electron donors, but higher activity was observed with NADH. Analysis of the reaction product revealed that KdgG catalyzes reversible reduction of KDG to form 3-deoxy-D-mannonate. Molecular phylogenetic analysis indicated that KdgG and its homologs distributed in the genus Thermus form a novel clade among type-2 malate/L-lactate dehydrogenase family proteins.

Lactate Dehydrogenase to Albumin ratio as a Predictive Factor of COVID-19 Patients' Outcome; a Cross-sectional Study.

Introduction:  Despite the increasing vaccination coverage, COVID-19 is still a concern. With the limited health care capacity, early risk stratification is crucial to identify patients who should be prioritized for optimal management. The present study investigates whether on-admission lactate dehydrogenase to albumin ratio (LAR) can be used to predict COVID-19 outcomes. Methods: This retrospective cross-sectional study evaluated hospitalized COVID-19 patients in an academic referral center in Iran from May 2020 to October 2020. The area under the receiver operating characteristic (ROC) curve (AUC) was used to evaluate the value of LAR in the prediction of mortality. The Yuden index was used to find the optimal cut-off of LAR to distinguish severity. Patients were classified into three groups (LAR tertiles), first: LAR<101.46, second: 101.46≤LAR< 148.78, and third group: LAR≥148.78. Logistic regression analysis was used to identify the association between tertiles of LAR, as well as the relationship between each one-unit increase in LAR with mortality and ICU admission in three models, based on potential confounding variables. Results: A total of 477 patients were included. Among all patients, 100 patients (21%) died, and 121 patients (25.4%) were admitted to intensive care unit (ICU). In the third group, the risk of mortality and ICU admission increased 7.78 times (OR=7.78, CI: 3.95-15.26; p <0.0001) and 4.49 times (OR=4.49, CI: 2.01-9.04; p <0.0001), respectively, compared to the first group. The AUC of LAR for prediction of mortality was 0.768 (95% CI 0.69- 0.81). LAR ≥ 136, with the sensitivity and specificity of 72% (95%CI: 62.1-80.5) and 70% (95%CI: 64.9-74.4), respectively, was the optimal cut-off value for predicting mortality. Conclusion: High LAR was associated with higher odds of COVID-19 mortality, ICU admission, and length of hospitalization. On-admission LAR levels might help health care workers identify critical patients early on.

Electroacupuncture preconditioning alleviates myocardial ischemia-reperfusion injury through the hypothalamic paraventricular nucleus- interposed nucleus nerve pathway.

OBJECTIVE: To explore whether the paraventricular nucleus (PVN) participates in regulation of the anti-myocardial ischemia-reperfusion injury (MIRI) effect of electroacupuncture (EA) and whether this is achieved through the PVN-interposed nucleus (IN) neural pathway. METHODS: The modeling method of myocardial ischemia reperfusion injury was achieved by ligating the left anterior descending coronary artery in Sprague-Dawley rats. We used the Powerlab multi-channel physiological recorder system to record electro-cardiograms and analyze the changes in ST segment displacement; 2,3,5-Triphenyltetrazolium chloride staining was used to observe the percentage of myocardial infarction areas. Detecting cardiac troponin I (cTnI), lactate dehydrogenase (LDH) in serum was done with an enzyme-linked immunosorbent assay kit. Morphological changes in the myocardium were detected in each group with hematoxylin-eosin staining of paraffin sections. Detection of c-fos protein expression in the PVN of the hypothalamus was done with the immune-ofluorescence method. The Plexon multi-channel acquisition system recorded PVN neuron discharges and local field potentials in each group of rats. Offline Sorter software was used for cluster analysis. Neuro Explorer software was used to perform autocorrelation, raster and frequency characteristics and spectral energy analysis of neuron signals in each group. RESULTS: Compared with the MIRI model group, the areas of myocardial infarction in the EA group were significantly reduced; the expression of cTnI, LDH in serum was decreased significantly. The firing frequency of pyramidal cells in the PVN was significantly increased and the spectrum energy map showed energy was reduced, c-fos expression in PVN was reduced, this indicated that neuronal activity in the PVN participates in the effect of EA improving myocardial injury. In addition, we used the kainic acid method to lesion the IN and observed that the effect of EA was weakened. For example, the area of myocardial infarction of lesion IN + EA group in rats was significantly increased compared with that resulting from EA group, the expression of cTnI, LDH in serum was significantly increased, the firing frequency of pyramidal cells in the PVN was significantly reduced. A spectral energy diagram shows that the energy after damage was higher than that of EA group. At the same time, the expression of c-fos in the PVN increased again. CONCLUSION: Our results indicated that the PVN-IN nerve pathway may participate as an effective pathway of EA to improve the effect of myocardial injury.

Enantioselective Biosynthesis of L-Phenyllactic Acid From Phenylpyruvic Acid In Vitro by L-Lactate Dehydrogenase Coupling With Glucose Dehydrogenase.

As a valuable versatile building block, L-phenyllactic acid (L-PLA) has numerous applications in the fields of agriculture, pharmaceuticals, and biodegradable plastics. However, both normally chemically synthesized and naturally occurring PLA are racemic, and the production titer of L-PLA is not satisfactory. To improve L-PLA production and reduce the high cost of NADH, an in vitro coenzyme regeneration system of NADH was achieved using the glucose dehydrogenase variant LsGDHD255C and introduced into the L-PLA production process. Here an NADH-dependent L-lactate dehydrogenase-encoding variant gene (L-Lcldh1Q88A/I229A) was expressed in Pichia pastoris GS115. The specific activity of L-LcLDH1Q88A/I229A (Pp) was as high as 447.6 U/mg at the optimum temperature and pH of 40°C and 5.0, which was 38.26-fold higher than that of wild-type L-LcLDH1 (Pp). The catalytic efficiency (k cat/K m) of L-LcLDH1Q88A/I229A (Pp) was 94.3 mM-1 s-1, which was 67.4- and 25.5-fold higher than that of L-LcLDH1(Pp) and L-LcLDH1Q88A/I229A (Ec) expressed in Escherichia coli, respectively. Optimum reactions of L-PLA production by dual-enzyme catalysis were at 40°C and pH 5.0 with 10.0 U/ml L-LcLDH1Q88A/I229A (Pp) and 4.0 U/ml LsGDHD255C. Using 0.1 mM NAD+, 400 mM (65.66 g/L) phenylpyruvic acid was completely hydrolyzed by fed-batch process within 6 h, affording L-PLA with 90.0% yield and over 99.9% ee p. This work would be a promising technical strategy for the preparation of L-PLA at an industrial scale.

Higher Muscle Damage Triggered by Shorter Inter-Set Rest Periods in Volume-Equated Resistance Exercise.

Objectives: The aim of the manuscript was to analyze the effects of two rest periods between volume-equated resistance exercise (RE) on inflammatory responses (cytokines and leukocyte) and muscle damage. Methods: Ten trained men (26.40 ± 4.73 years, 80.71 ± 8.95 kg, and 176.03 ± 6.11 cm) voluntarily participated in training sessions consisting of five sets of 10 reps performed at 10-RM on (1) the barbell bench press followed by (2) leg press, with either 1- or 3-min rest between sets and exercises. Circulating concentrations of different biomarkers was measured before (Pre), and after 3 h (excepted for cytokines), 6, 12, and 24 h from exercise. The rate of perceived exertion (RPE) was recorded after each set on both planned visits. Results: We found greater increases triggered by the 1-min rest period in Creatine Kinase (CK), occurring from 12 to 24 h post-exercise compared to the 3-min rest condition. A significant increase in the 1-min rest condition was also observed in the total number of leukocytes, neutrophils, and monocytes. The 1-min rest period also triggered increases compared to baseline in pro-inflammatory cytokines [Interleukin 1 beta (IL-1ß), p = 0.004; tumor necrosis factor α (TNF-α), p = 0.01; and granulocyte-macrophage colony-stimulating factor (GM-CSF), p = 0.01], which were more evident after 6 and 12 h post-exercise. Similarly, increases in anti-inflammatory cytokines [Interleukin 5 (IL-5), p = 0.01; Interleukin 6 (IL-6), p = 0.01; and Interleukin 10 (IL-10), p = 0.01] at all time-points were observed. Conclusion: Our results indicate that a 1-min rest condition in volume-equated RE promoted greater overall muscle tissue damage with a longer duration of the inflammatory processes compared to a 3-min rest.

Clinical characteristics and hematological parameters associated with disease severity in COVID-19 positive pregnant women undergoing cesarean section: A single-center experience.

AIM: The study aimed to describe clinical characteristics and outcomes of pregnant women with COVID-19 undergoing cesarean section, and evaluated the association of blood values at admission with severe COVID-19 disease in this group of patients. METHOD: We retrospectively analyzed the clinical data of 110 patients infected with COVID-19 who underwent cesarean section at Adana City Education and Research Hospital in Turkey. The COVID-19 severity of the patients was classified as either severe or nonsevere disease according to World Health Organization of COVID-19 clinical management guidance. We compared blood values, clinical characteristics, and outcomes between severe and nonsevere patients. Receiver operating characteristics (ROC) curves analyses and area under the ROC curve (AUC) value was calculated to evaluate the predictive value of blood parameters on the COVID-19 severity. RESULTS: Of the 110 women, 12 were severe cases. Severe patients had higher ferritin, neutrophil-to-lymphocyte ratio (NLR), lactate dehydrogenase (LDH), alanine transaminase (ALT), aspartate transaminase (AST), and procalcitonin levels on admission (p < 0.05). The ROC analysis demonstrated AUC of NLR, LDH, AST, ALT, ferritin, and procalcitonin was 0.757, 0.856, 0.840, 0.771, 0.821, and 0.698, respectively. The LDH had a maximum specificity (90.8%), with the cutoff value of 365. The O-blood group was more likely to have severe illness than the non-O-blood group (relative risk: 3.6; 95% confidence interval; 1.2-10.4). CONCLUSION: This study shows that LDH values at admission are an early and powerful predictor of severe infection for pregnant women with COVID-19 who will undergo a cesarean section.

Relationship between L-lactate dehydrogenase and multidrug resistance in Staphylococcus xylosus.

Staphylococcus xylosus is a gram-positive bacterium that has attracted much attention due to its increasing clinical appearance, frequently associated with serious multidrug resistance cases. L-lactate dehydrogenase (LDH) has been related to drug resistance in several bacterial species. However, the mechanism of multidrug resistance in S. xylosus remains unclear as well as the involvement of LDH in such resistance. To explore the relationship between multidrug resistance and LDH in S. xylosus, we used tylosin-resistant S. xylosus as the parent strain to construct ldh knockout and complemented strains. Then, we tested their resistance to macrolides, lincosamides, tetracyclines, and aminoglycosides. In addition, the enzyme activity, metabolite content, and transcriptional level of key genes involved in the TCA cycle and thioredoxin system were determined to clarify the mechanism of resistance. We observed that the resistance to multiple antibiotics increased significantly after ldh knockout, especially that to lincomycin, whereas antibiotic sensitivity was partially restored in the complemented strain. The levels of pyruvate, nicotinamide adenine dinucleotide, and reactive oxygen species decreased significantly upon ldh knockout, and the activity of isocitrate dehydrogenase and malate dehydrogenase decreased. These results indicate that the lack of LDH promotes multidrug resistance in S. xylosus by inhibiting the TCA cycle and regulating the thioredoxin system.

Characterization of a Novel Thermostable Dye-Linked l-Lactate Dehydrogenase Complex and Its Application in Electrochemical Detection.

Flavoenzyme dye-linked l-lactate dehydrogenase (Dye-LDH) is primarily involved in energy generation through electron transfer and exhibits potential utility in electrochemical devices. In this study, a gene encoding a Dye-LDH homolog was identified in a hyperthermophilic archaeon, Sulfurisphaera tokodaii. This gene was part of an operon that consisted of four genes that were tandemly arranged in the Sf. tokodaii genome in the following order: stk_16540, stk_16550 (dye-ldh homolog), stk_16560, and stk_16570. This gene cluster was expressed in an archaeal host, Sulfolobus acidocaldarius, and the produced enzyme was purified to homogeneity and characterized. The purified recombinant enzyme exhibited Dye-LDH activity and consisted of two different subunits (products of stk_16540 (α) and stk_16550 (ß)), forming a heterohexameric structure (α3ß3) with a molecular mass of approximately 253 kDa. Dye-LDH also exhibited excellent stability, retaining full activity upon incubation at 70 °C for 10 min and up to 80% activity after 30 min at 50 °C and pH 6.5-8.0. A quasi-direct electron transfer (DET)-type Dye-LDH was successfully developed by modification of the recombinant enzyme with an artificial redox mediator, phenazine ethosulfate, through amine groups on the enzyme's surface. This study is the first report describing the development of a quasi-DET-type enzyme by using thermostable Dye-LDH.

Effect of hydrogen-rich water on the lactic acid level in metformin-treated diabetic rats under hypoxia.

The present study aims to investigate the impact of hydrogen-rich water on the lactic acid level in metformin-treated diabetic rats under hypoxia. Thirty Sprague-Dawley rats were randomly divided into five groups, including normal diet group, and diabetes model (DM) group, DM + metformin treatment (DMM) group, DMM + hypoxia treatment (DMMH) group and DMMH + hydrogenrich water (DMMHR) group. We found that the levels of lactic acid, pyruvate and lactate dehydrogenase were significantly lower in the blood of DMMHR group than DMMH group. Superoxide dismutase and glutathione levels in liver and heart were significantly higher in DMMH group after hydrogen-rich water treatment, while malondialdehyde and oxidized glutathione levels were decreased in DMMHR group when compared with DMMH group, which indicates that hydrogen-rich water could reduce oxidative stress. qPCR analysis demonstrated that that pro-apoptotic genes Bax/Caspase-3 were upregulated in DM group and metformin treatment suppressed their upregulation (DMM group). However, hypoxic condition reversed the effect of metformin on apoptotic gene expression, and hydrogen-rich water showed little effect on these genes under hypoxia. HE staining showed that hydrogen-rich water prevented myocardial fiber damages under hypoxia. In summary, we conclude that hydrogen-rich water could prevent lactate accumulation and reduce oxidant stress in diabetic rat model to prevent hypoxia-induced damages. It could be served as a potential agent for diabetes patients with metformin treatment to prevent lactic acidosis and reduce myocardial damages under hypoxic conditions.

The Value of Lactate Dehydrogenase in Predicting Rhabdomyolysis-Induced Acute Renal Failure; a Narrative Review.

INTRODUCTION: Determining the diagnostic value of available biomarkers in predicting rhabdomyolysis-induced acute kidney injury (AKI) is a priority. This study aimed to review the current evidence about the value of lactate dehydrogenase (LDH) in this regard. METHODS: In this narrative review, the papers in PubMed, Embase, and web of science were studied. The keywords prognosis, prognoses, prognostic, LDH, rhabdomyolysis, emergency patients, and acute kidney failure or AKI had been selected from MeSH medical dictionary. Related papers written in English and published from November 2007 to December 2020 were selected. RESULTS: Finally, 14 articles were accepted for analysis. Among the selected articles, four were randomized clinical trials, seven were cross-sectional, and three were case-control studies. The results of the present review showed that abuse of illegal drugs is the most common cause of rhabdomyolysis. AKI is the most serious complication of rhabdomyolysis reported in the studies. These studies have shown a three-fold increase in AKI following drug-induced rhabdomyolysis. The review of the included articles shows that high LDH can predicts AKI, especially in critical and emergency situations such as rhabdomyolysis where there is a risk of death if diagnosed late. These studies show that LDH increases in the presence of renal failure and tissue damage. CONCLUSION: Serum LDH is an appropriate and cost-effective prognostic indicator that can be used for risk classification of patients at risk for rhabdomyolysis-induced AKI.

Hematological profile and biochemical markers of COVID-19 non-survivors: A retrospective analysis.

BACKGROUND: Coronavirus disease is primarily transmitted through the respiratory route and bodily contact. The fatality in COVID-19 cases was alarming in the initial days. This study analyzes hematological and biochemical markers of COVID-19 non-survivors. MATERIAL AND METHODS: In this single-center study, records of 249 patients hospitalized with COVID-19 were studied for hematological profile and biochemical markers. Records of patients with laboratory-confirmed COVID-19 disease hospitalized between April 14, 2020, to August 15, 2020, were included in the analysis. RESULTS: Significantly, the disease mortality was associated with increased procalcitonin (P < 0.05), C-reactive protein (P < 0.05), aspartate transaminase (P < 0.05), serum potassium (P < 0.05), neutrophils count (P < 0.05), white blood cell count (P < 0.05), prothrombin time (P < 0.05) and activated prothrombin time (P < 0.05) in patients reported abnormal x-ray findings. Further, patients with abnormal radiological findings significantly showed a reduced level of lymphocyte counts (P < 0.05), oxygen saturation (P < 0.05), and partial oxygen pressure (P < 0.05). Reduced level of aspartate aminotransferase (P < 0.05), alanine aminotransferase (P < 0.05) and lactate dehydrogenase (P < 0.05) reported significant association with mortality among patients with COVID-19. CONCLUSIONS: The clinicians may consider the hematological and biochemical parameters in the patients with COVID-19 in future decision-making. These indicators might support clinical decisions to identify high fatality cases and poor diagnosis in the initial admission phase. In COVID-19 patients, we recommend close monitoring on procalcitonin, C-reactive protein, neutrophils count, and white blood cell count as a clinical indicator for potential progression to critical illness.

Use of data-independent acquisition mass spectrometry for comparative proteomics analyses of sera from pregnant women with intrahepatic cholestasis of pregnancy.

We used data-independent acquisition (DIA) proteomics technology followed by ELISAs and automated biochemical analyses to identify and validate protein expression levels in Intrahepatic Cholestasis of Pregnancy (ICP) and healthy pregnant controls. We employed bioinformatics to identify metabolic processes associated with differentially expressed proteins.The expression levels of two proteins (S100-A9 and the L-lactate dehydrogenase A chain) were significantly higher in ICP patients than in controls; the areas under the receiver operating characteristic (ROC) curves (AUCs) were 0.774 and 0.828, respectively. The expression levels of two other proteins (apolipoprotein A-I and cholinesterase) were significantly lower in patients, with values of 0.900 and 0.842, respectively. Multiple logistic regression showed that a combination of the levels of the four proteins optimized the AUC (0.962), thus more reliably diagnosing ICP. The levels of all four proteins were positively associated with that of total bile acids. Bioinformatics analyses indicated that the four proteins principally affected neutrophil activation involved in the immune response, cell adhesion, lipoprotein metabolism, and the PPAR signaling pathway. SIGNIFICANCE: This preliminary work improves our understanding of changes in serum levels of protein in pregnant women with ICP. The four proteins may serve as novel noninvasive biomarkers for ICP.

Rational engineering of the Plasmodium falciparuml-lactate dehydrogenase loop involved in catalytic proton transfer to improve chiral 2-hydroxybutyric acid production.

l-lactate dehydrogenases (LDHs) has been widely studied for their ability to reduce 2-keto acids for the production of 2-hydroxy acids, whereby 2-hydroxybutyric acids (2-HBA) is among the most important fundamental building blocks for synthesizing pharmaceuticals and biodegradable materials. However, LDHs usually show low activity towards 2-keto acids with longer side chain such as 2-oxobutyric acid (2-OBA). Here rational engineering of the Plasmodium falciparum LDH loop with residue involved in the catalytic proton transfer was initially studied. By combining homology alignment and structure-based design approach, we found that changing the charge characteristics or hydrogen bond network interactions of this loop could improve enzymatic catalytic activities and stabilities towards 2-OBA. Compared with wild type, variant N197Dldh showed 1.15 times higher activity and 2.73 times higher Kcat/Km. The half-life of variant N197Dldh at 40 °C increased to 77.9 h compared with 50.4 h of wild type. Furthermore, asymmetric synthesis of (S)-2-HBA with coenzyme regeneration revealed 95.8 g/L production titer within 12 h for variant N197Dldh, 2.05 times higher than using wild type. Our study indicated the importance of loop with residues involved in the catalytic proton transfer process, and the engineered LDH would be more suitable for (S)-2-HBA production.