-
The Journal of Biological Chemistry Jun 2024L-Fucose (6-deoxy-L-galactose), a monosaccharide abundant in glycolipids and glycoproteins produced by mammalian cells, has been extensively studied for its role in...
L-Fucose (6-deoxy-L-galactose), a monosaccharide abundant in glycolipids and glycoproteins produced by mammalian cells, has been extensively studied for its role in intracellular biosynthesis and recycling of GDP-L-fucose for fucosylation. However, in certain mammalian species, L-fucose is efficiently broken down to pyruvate and lactate in a poorly understood metabolic pathway. In the 1970s, L-fucose dehydrogenase, an enzyme responsible for the initial step of this pathway, was partially purified from pig and rabbit livers and characterized biochemically. However, its molecular identity remained elusive until recently. This study reports the purification, identification, and biochemical characterization of the mammalian L-fucose dehydrogenase. The enzyme was purified from rabbit liver approximately 340-fold. Mass spectrometry analysis of the purified protein preparation identified mammalian hydroxysteroid 17-β dehydrogenase 14 (HSD17B14) as the sole candidate enzyme. Rabbit and human HSD17B14 were expressed in HEK293T and Escherichia coli, respectively, purified and demonstrated to catalyze the oxidation of L-fucose to L-fucono-1,5-lactone, as confirmed by mass spectrometry and NMR analysis. Substrate specificity studies revealed that L-fucose is the preferred substrate for both enzymes. The human enzyme exhibited a catalytic efficiency for L-fucose that was 359-fold higher than its efficiency for estradiol. Additionally, recombinant rat HSD17B14 exhibited negligible activity towards L-fucose, consistent with the absence of L-fucose metabolism in this species. The identification of the gene encoding mammalian L-fucose dehydrogenase provides novel insights into the substrate specificity of enzymes belonging to the 17-β-hydroxysteroid dehydrogenase family. This discovery also paves the way for unraveling the physiological functions of the L-fucose degradation pathway, which remains enigmatic.
PubMed: 38944119
DOI: 10.1016/j.jbc.2024.107501 -
International Journal of Biological... Jun 2024Lytic polysaccharide monooxygenase (LPMO)-catalyzed oxidative processes play a major role in natural biomass conversion. Despite their oxidative cleavage at the surface...
Lytic polysaccharide monooxygenase (LPMO)-catalyzed oxidative processes play a major role in natural biomass conversion. Despite their oxidative cleavage at the surface of polysaccharides, understanding of their mode of action, and the impact of structural patterns of the cellulose fiber on LPMO activity is still not fully understood. In this work, we investigated the action of two different LPMOs from Podospora anserina on celluloses showing different structural patterns. For this purpose, we prepared cellulose II and cellulose III allomorphs from cellulose I cotton linters, as well as amorphous cellulose. LPMO action was monitored in terms of surface morphology, molar mass changes and monosaccharide profile. Both PaLPMO9E and PaLPMO9H were active on the different cellulose allomorphs (I, II and III), and on amorphous cellulose (PASC) whereas they displayed a different behavior, with a higher molar mass decrease observed for cellulose I. Overall, the pretreatment with LPMO enzymes clearly increased the accessibility of all types of cellulose, which was quantified by the higher carboxylate content after carboxymethylation reaction on LPMO-pretreated celluloses. This work gives more insight into the action of LPMOs as a tool for deconstructing lignocellulosic biomass to obtain new bio-based building blocks.
PubMed: 38944074
DOI: 10.1016/j.ijbiomac.2024.133429 -
International Journal of Biological... Jun 2024In traditional Chinese medicine, Lycium barbarum is of rich medicinal value, and its polysaccharides are particularly interesting due to their significant...
In traditional Chinese medicine, Lycium barbarum is of rich medicinal value, and its polysaccharides are particularly interesting due to their significant pharmacological effects and potential health benefits. This study investigated the immunomodulatory effects of Lycium barbarum polysaccharides (LBPs) by examining their interaction with the TLR4/MD-2 complex and the impacts of gastrointestinal digestion on these interactions. We discovered that the affinity binding of LBPs for TLR4/MD-2 and their cytokine induction capability are influenced by molecular weight, with medium-sized LBPs (100-300 kDa) exhibiting stronger binding affinity and induction capability. Conversely, LBPs smaller than 10 kDa showed reduced activity. Additionally, the content of arabinose and galactose within the LBPs fractions was found to correlate positively with both receptor affinity and cytokine secretion. Simulated gastrointestinal digestion resulted in the degradation of LBPs into smaller fragments that are rich in glucose. Although these fragments exhibited decreased binding affinity to the TLR4/MD-2 complex, they maintained their activity to promote cytokine production. Our findings highlight the significance of molecular weight and specific monosaccharide composition in the immunomodulatory function of LBPs and emphasize the influence of gastrointestinal digestion on the effects of LBPs. This research contributes to a better understanding of the mechanisms underlying the immunomodulatory effects of traditional Chinese medicine polysaccharides and their practical application.
PubMed: 38944071
DOI: 10.1016/j.ijbiomac.2024.133500 -
International Journal of Biological... Jun 2024Glycoside hydrolases (GHs) are pivotal in the hydrolysis of the glycosidic bonds of sugars, which are the main carbon and energy sources. The genome of Marinomonas sp....
Glycoside hydrolases (GHs) are pivotal in the hydrolysis of the glycosidic bonds of sugars, which are the main carbon and energy sources. The genome of Marinomonas sp. ef1, an Antarctic bacterium, contains three GHs belonging to family 3. These enzymes have distinct architectures and low sequence identity, suggesting that they originated from separate horizontal gene transfer events. M-GH3_A and M-GH3_B, were found to differ in cold adaptation and substrate specificity. M-GH3_A is a bona fide cold-active enzyme since it retains 20 % activity at 10 °C and exhibits poor long-term thermal stability. On the other hand, M-GH3_B shows mesophilic traits with very low activity at 10 °C (< 5 %) and higher long-term thermal stability. Substrate specificity assays highlight that M-GH3_A is a promiscuous β-glucosidase mainly active on cellobiose and cellotetraose, whereas M-GH3_B is a β-xylosidase active on xylan and arabinoxylan. Structural analysis suggests that such functional differences are due to their differently shaped active sites. The active site of M-GH3_A is wider but has a narrower entrance compared to that of M-GH3_B. Genome-based prediction of metabolic pathways suggests that Marinomonas sp. ef1 can use monosaccharides derived from the GH3-catalyzed hydrolysis of oligosaccharides either as a carbon source or for producing osmolytes.
PubMed: 38944065
DOI: 10.1016/j.ijbiomac.2024.133449 -
The Veterinary Quarterly Dec 2024Mistletoe is an herb that grows on duku plants (Lancium demosticum) and is known as benalu duku (BD) in Indonesia. It is predicted to have benefits such as anticancer...
Mistletoe is an herb that grows on duku plants (Lancium demosticum) and is known as benalu duku (BD) in Indonesia. It is predicted to have benefits such as anticancer or antiviral properties, and it is also thought to have anti-diabetic pharmacological activity. Quercetin-like compounds (QLCs) are secondary metabolites with antidiabetic activity that are expected to lower blood sugar levels in animals after oral administration. This study aimed to analyze the ability of QLCs to reduce random blood sugar levels using experimental animals as clinical models. The research method used was exploratory, which used a before-after test model, and observations were made on the random blood sugar levels after treatment. Secondary metabolites were extracted from BD leaves, which were then screened. Diabetes was induced in 30 rats (Rattus norvegicus) by the administration of streptozotocin at 0.045 mg/g body weight daily for 2 days. The antidiabetic effects of the secondary metabolite at doses of 0.5 mg/kg body weight (twice a day) when administered orally for up to 5 days were tested in diabetic rats. The random sugar levels (mg/dL) were measured using a One Touch Ultra Plus medical device for observation of randomized blood sugar levels. Results and novelty: The results revealed that the secondary metabolite, as an analyte from the BD leaf extract, can significantly reduce random blood sugar levels. The secondary metabolite extracted from BD, could be used to treat diabetes in rats.
Topics: Animals; Diabetes Mellitus, Experimental; Rats; Hypoglycemic Agents; Quercetin; Blood Glucose; Male; Plant Extracts; Mistletoe; Administration, Oral; Plant Leaves
PubMed: 38943615
DOI: 10.1080/01652176.2024.2372090 -
Endocrinology, Diabetes & Metabolism Jul 2024Data suggest malfunctioning mitochondria reduce oxidation and adenosine triphosphate (ATP) production, disrupting insulin signalling. Cytochrome c (CC), acylcarnitine... (Observational Study)
Observational Study Comparative Study
INTRODUCTION
Data suggest malfunctioning mitochondria reduce oxidation and adenosine triphosphate (ATP) production, disrupting insulin signalling. Cytochrome c (CC), acylcarnitine (AC) and citrate synthase (CS) are essential components of the mitochondria machinery and can be used as reliable biomarkers of mitochondrial dysfunction. This study aimed to determine whether mitochondrial biomarkers (AC, CS and CC) are altered in individuals with type 2 diabetes mellitus (T2DM) and to examine the association between these biomarkers and insulin resistance.
METHODOLOGY
A cross-sectional observational study that recruited 170 participants (88 with T2DM and 82 without DM) was conducted. Blood samples were collected from the recruits and analysed for levels of fasting glucose (FBG), AC, CS, CC, insulin, total cholesterol, triglycerides (TG), glycated haemoglobin (HbA1c) and magnesium. Blood pressure (BP) and anthropometric characteristics of participants were also taken. Appropriate formulas were used to determine %body fat, body mass index (BMI), waist-to-hip ratio (WHR), the homeostatic model assessment for insulin resistance (HOMA-IR) and insulin sensitivity (HOMA-β).
RESULTS
Patients with T2DM had higher levels of CC, %body fat, FBG, TG, HbA1c, BMI and HOMA-IR than controls (p < 0.05, respectively). Results showed a significant relationship between circulating CC levels versus HOMA-β (r = -0.40, p = 0.001), CS (r = -0.70, p = 0.001) and AC (r = -0.72, p = 0.001) levels in patients with T2DM. The adjusted odds increased in the T2DM patients for VLDL (OR = 6.66, p = 0.002), HbA1c (OR = 6.50, p = 0.001), FPG (OR = 3.17, p = 0.001), TG (OR = 2.36, p = 0.010), being female (OR = 2.09, p = 0.020) and CC (OR = 1.14, p = 0.016).
CONCLUSION
Overall, alterations in mitochondrial biomarkers, measured by AC, CC and CS, were observed in people with T2DM and showed a direct relationship with insulin resistance. These findings are potentially significant in Africa, although additional confirmation from a larger cohort is necessary.
Topics: Humans; Diabetes Mellitus, Type 2; Insulin Resistance; Cross-Sectional Studies; Male; Female; Biomarkers; Middle Aged; Mitochondria; Adult; Carnitine; Cytochromes c; Citrate (si)-Synthase; Glycated Hemoglobin; Blood Glucose; Aged; Body Mass Index
PubMed: 38943337
DOI: 10.1002/edm2.507 -
Nigerian Journal of Clinical Practice Jun 2024Exercise or exercise capacity is a vital physiological function. It is known that certain cytokines support muscle function during exercise and, as a result, increase...
BACKGROUND
Exercise or exercise capacity is a vital physiological function. It is known that certain cytokines support muscle function during exercise and, as a result, increase exercise capacity.
AIMS
In this study, the effect of metformin administered in combination with exercise on osteocalcin (OCN), insulin, and interleukin-6 (IL-6) levels in rats was investigated.
METHODS
Forty-two male Wistar rats were used in this study. The animals were randomly divided into six groups: control (CONT), only exercise (EXE), metformin_100 mg/kg (Met100), metformin_200 mg/kg (Met200), metformin_100 mg/kg+exercise (Met100+EXE), and metformin_200 mg/kg+exercise (Met200+EXE). A 10-week intervention was conducted, excluding exercise training. During the experiment, the groups receiving metformin application (100 or 200 mg/kg) were administered with metformin. At the end of the study, serum samples were collected from the rats to determine the levels of osteocalcin, insulin, and IL-6 using the enzyme-linked immunosorbent assay method. In addition, glucose levels and body weights were evaluated. GraphPad Prism was used for the analyses.
RESULTS
The OCN and insulin levels of the Met100+EXE and Met200+EXE groups were found to be higher compared to the CONT, Met100, and Met200 groups (P < 0.05). The IL-6 level of the EXE group was determined to be higher than that of the CONT, Met100, and Met200 groups (P < 0.01). It was observed that both exercise and the individual or combined application of metformin resulted in lower blood glucose levels compared to the CONT group. The mean body weight of the EXE group was higher than that of the other groups.
CONCLUSION
The combined application of metformin and exercise has increased osteocalcin and insulin levels compared to metformin application alone.
Topics: Animals; Metformin; Interleukin-6; Osteocalcin; Rats, Wistar; Male; Rats; Physical Conditioning, Animal; Insulin; Hypoglycemic Agents; Blood Glucose; Body Weight
PubMed: 38943302
DOI: 10.4103/njcp.njcp_884_23 -
Trials Jun 2024Acute leukaemias (AL) are life-threatening blood cancers that can be potentially cured with treatment involving myelosuppressive, multiagent, intensive chemotherapy...
Biomarker Driven Antifungal Stewardship (BioDriveAFS) in acute leukaemia-a multi-centre randomised controlled trial to assess clinical and cost effectiveness: a study protocol for a randomised controlled trial.
BACKGROUND
Acute leukaemias (AL) are life-threatening blood cancers that can be potentially cured with treatment involving myelosuppressive, multiagent, intensive chemotherapy (IC). However, such treatment is associated with a risk of serious infection, in particular invasive fungal infection (IFI) associated with prolonged neutropenia. Current practice guidelines recommend primary antifungal (AF) prophylaxis to be administered to high-risk patients to reduce IFI incidence. AFs are also used empirically to manage prolonged neutropenic fever. Current strategies lead to substantial overuse of AFs. Galactomannan (GM) and β-D-glucan (BG) biomarkers are also used to diagnose IFI. Combining both biomarkers may enhance the predictability of IFI compared to administering each test alone. Currently, no large-scale randomised controlled trial (RCT) has directly compared a biomarker-based diagnostic screening strategy without AF prophylaxis to AF prophylaxis (without systematic biomarker testing).
METHODS
BioDriveAFS is a multicentre, parallel, two-arm RCT of 404 participants from UK NHS Haematology departments. Participants will be allocated on a 1:1 basis to receive either a biomarker-based antifungal stewardship (AFS) strategy, or a prophylactic AF strategy, which includes existing standard of care (SoC). The co-primary outcomes will be AF exposure in the 12-month post randomisation and the patient-reported EQ-5D-5L measured at 12-month post randomisation. Secondary outcomes will include total AF exposure, probable/proven IFI, survival (all-cause mortality and IFI mortality), IFI treatment outcome, AF-associated adverse effects/events/complications, resource use, episodes of neutropenic fever requiring hospital admission or outpatient management, AF resistance in fungi (non-invasive and invasive) and a Desirability of Outcome Ranking. The trial will have an internal pilot phase during the first 9 months. A mixed methods process evaluation will be integrated in parallel to the internal pilot phase and full trial, aiming to robustly assess how the intervention is delivered. Cost-effectiveness analysis will also be performed.
DISCUSSION
The BioDriveAFS trial aims to further the knowledge of strategies that will safely optimise AF use through comparison of the clinical and cost-effectiveness of a biomarker-led diagnostic strategy versus prophylactic AF to prevent and manage IFI within acute leukaemia. The evidence generated from the study will help inform global clinical practice and approaches within antifungal stewardship.
TRIAL REGISTRATION
ISRCTN11633399. Registered 24/06/2022.
Topics: Humans; Antifungal Agents; Cost-Benefit Analysis; Randomized Controlled Trials as Topic; Invasive Fungal Infections; Multicenter Studies as Topic; Biomarkers; Galactose; Mannans; Treatment Outcome; beta-Glucans; Antimicrobial Stewardship; Leukemia; Time Factors; Cost-Effectiveness Analysis
PubMed: 38943201
DOI: 10.1186/s13063-024-08272-w -
Cardiovascular Diabetology Jun 2024The Triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, has been implicated in the risk of ischemic stroke. However, the interplay between TyG...
BACKGROUND
The Triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, has been implicated in the risk of ischemic stroke. However, the interplay between TyG levels, lifestyle factors, and their collective impact on stroke risk in non-diabetic populations remains inadequately explored. This study aims to evaluate the association of ischemic stroke with the joint development of the TyG index and lifestyle in the non-diabetic population.
METHODS
In this prospective cohort study, data was collected across three consecutive biennial surveys of the Kailuan Study from 2006 to 2011. The dual-trajectory model was used to determine the temporal development of TyG levels and lifestyle scores. Statistical analysis involved Cox regression models to evaluate the association between TyG-lifestyle trajectories and ischemic stroke risk, adjusting for potential confounders.
RESULTS
A total of 44,403 participants were included, with five distinct TyG levels and lifestyle scores trajectory subtypes identified. In the multivariable-adjusted analyses, significant differences in ischemic stroke risk among the trajectory subtypes. Group 5, characterized by the highest TyG levels and moderate lifestyle scores, exhibited the greatest ischemic stroke risk (HR = 1.81, 95% CI: 1.51-2.18), while group 4, with moderate TyG levels and higher lifestyle scores, demonstrated the lowest risk (HR = 1.19, 95% CI: 1.04-1.37), compared with group 3. Participants with elevated TyG levels were at an increased risk of ischemic stroke in cases of pronounced insulin resistance, even with a healthy lifestyle.
CONCLUSIONS
This study reveals the significant associations between the identified TyG and lifestyle trajectories and the stratification of ischemic stroke risk among non-diabetics. The TyG index is a valuable indicator for assessing insulin resistance. However, the potential benefits of lifestyle changes for those with significantly high TyG levels need to be clarified by more research to develop more effective stroke prevention strategies.
Topics: Humans; Male; Middle Aged; Female; Prospective Studies; Ischemic Stroke; Risk Factors; Risk Assessment; Biomarkers; Blood Glucose; China; Aged; Insulin Resistance; Life Style; Triglycerides; Risk Reduction Behavior; Time Factors; Adult; Prognosis; Healthy Lifestyle
PubMed: 38943172
DOI: 10.1186/s12933-024-02313-z -
Cardiovascular Diabetology Jun 2024Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of hospitalization for heart failure and cardiovascular death with type 2 diabetes; however, their... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce the risk of hospitalization for heart failure and cardiovascular death with type 2 diabetes; however, their effect on arrhythmias is unclear. The purpose of this study was to investigate the effects of empagliflozin on ventricular arrhythmias in patients with type 2 diabetes.
METHODS
A total of 150 patients with type 2 diabetes who were treated with an implantable cardioverter-defibrillator or cardiac resynchronization therapy defibrillator (ICD/CRT-D) were randomized to once-daily empagliflozin or placebo for 24 weeks. The primary endpoint was the change in the number of ventricular arrhythmias from the 24 weeks before to the 24 weeks during treatment. Secondary endpoints included the change in the number of appropriate device discharges and other values.
RESULTS
In the empagliflozin group, the number of ventricular arrhythmias recorded by ICD/CRT-D decreased by 1.69 during treatment compared to before treatment, while in the placebo group, the number increased by 1.79. The coefficient for the between-group difference was - 1.07 (95% confidence interval [CI] - 1.29 to - 0.86; P < 0.001). The change in the number of appropriate device discharges during and before treatment was 0.06 in the empagliflozin group and 0.27 in the placebo group, with no significant difference between the groups (P = 0.204). Empagliflozin was associated with an increase in blood ketones and hematocrit and a decrease in blood brain natriuretic peptide and body weight.
CONCLUSIONS
In patients with type 2 diabetes treated with ICD/CRT-D, empagliflozin reduces the number of ventricular arrhythmias compared with placebo. Trial registration jRCTs031180120.
Topics: Humans; Diabetes Mellitus, Type 2; Glucosides; Benzhydryl Compounds; Male; Sodium-Glucose Transporter 2 Inhibitors; Female; Aged; Middle Aged; Treatment Outcome; Time Factors; Defibrillators, Implantable; Electric Countershock; Double-Blind Method; Japan; Cardiac Resynchronization Therapy; Blood Glucose
PubMed: 38943159
DOI: 10.1186/s12933-024-02309-9