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706,451 result(s) for "Enzyme I"
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Effect of Ginkgo biloba special extract EGb 761® on human cytochrome P450 activity: a cocktail interaction study in healthy volunteers
Purpose We assessed the human in vivo metabolic drug interaction profile of Ginkgo biloba extract EGb 761® with respect to the activities of major cytochrome P450 (CYP) enzymes. Methods A single-center, open-label, randomized, three-fold crossover, cocktail phenotyping design was applied. In random order, the following treatments were administered to 18 healthy men and women for 8 days each: placebo twice daily, EGb 761® 120 mg twice daily, and EGb 761® 240 mg in the morning and placebo in the evening. In the morning of day 8, administration was performed together with the orally administered phenotyping cocktail (enzyme, metric): 150 mg caffeine (CYP1A2, paraxanthine/caffeine plasma ratio 6-h postdose), 125 mg tolbutamide (CYP2C9, plasma concentration 24-h postdose), 20 mg omeprazole (CYP2C19, omeprazole/5-hydroxy omeprazole plasma ratio 3-h postdose), 30 mg dextromethorphan (CYP2D6, dextromethorphan/dextrorphan plasma ratio 3-h postdose), and 2 mg of midazolam (CYP3A, plasma concentration 6-h postdose). Formally, absence of a relevant interaction was assumed if the 90% confidence intervals (CIs) for EGb 761®/placebo ratios of the metrics were within the 0.70–1.43 range. Results EGb 761®/placebo ratios for phenotyping metrics were close to unity for all CYPs. Furthermore, respective CIs were within the specified margins for all ratios except CYP2C19 for EGb 761® 120 mg twice daily (90% CI 0.681–1.122) and for CYP2D6 for EGb 761® 240 mg once daily (90% CI 0.667–1.281). These findings were attributed to the intraindividual variability of the metrics used. All treatments were well tolerated. Conclusion EGb 761® has no relevant effect on the in vivo activity of the major CYP enzymes in humans and therefore has no relevant potential to cause respective metabolic drug–drug interactions.
Randomized Trial of Verubecestat for Prodromal Alzheimer’s Disease
In a randomized trial, patients with brain amyloid deposition but no dementia who received a β-site amyloid precursor protein–cleaving enzyme 1 inhibitor had no benefit with respect to clinical outcomes and worsening on some measures of cognition and daily function.
Efficacy and Safety of Nintedanib in Idiopathic Pulmonary Fibrosis
In this randomized, placebo-controlled trial, treatment with nintedanib, an intracellular inhibitor of multiple tyrosine kinases, led to a reduced rate of loss of forced vital capacity in patients with idiopathic pulmonary fibrosis. Idiopathic pulmonary fibrosis is a fatal lung disease characterized by worsening dyspnea and progressive loss of lung function. 1 A decline in forced vital capacity (FVC) is consistent with disease progression and is predictive of reduced survival time. 1 – 6 Idiopathic pulmonary fibrosis is believed to arise from an aberrant proliferation of fibrous tissue and tissue remodeling due to the abnormal function and signaling of alveolar epithelial cells and interstitial fibroblasts. 7 The activation of cell-signaling pathways through tyrosine kinases such as vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF) has been implicated in the pathogenesis of . . .
Small-Molecule Activators of a Proenzyme
Virtually all of the 560 human proteases are stored as inactive proenyzmes and are strictly regulated. We report the identification and characterization of the first small molecules that directly activate proenzymes, the apoptotic procaspases-3 and -6. It is surprising that these compounds induce autoproteolytic activation by stabilizing a conformation that is both more active and more susceptible to intermolecular proteolysis. These procaspase activators bypass the normal upstream proapoptotic signaling cascades and induce rapid apoptosis in a variety of cell lines. Systematic biochemical and biophysical analyses identified a cluster of mutations in procaspase-3 that resist small-molecule activation both in vitro and in cells. Compounds that induce gain of function are rare, and the activators reported here will enable direct control of the executioner caspases in apoptosis and in cellular differentiation. More generally, these studies presage the discovery of other proenzyme activators to explore fundamental processes of proenzyme activation and their fate-determining roles in biology.
Single-Agent Divarasib (GDC-6036) in Solid Tumors with a KRAS G12C Mutation
Among patients with cancers bearing the KRAS G12C mutation who received divarasib at a 400-mg dose, 56% with lung cancer, 36% with colorectal cancer, and 36% with other tumor types had a confirmed response.
MTH1 inhibition eradicates cancer by preventing sanitation of the dNTP pool
Cancers have dysfunctional redox regulation resulting in reactive oxygen species production, damaging both DNA and free dNTPs. The MTH1 protein sanitizes oxidized dNTP pools to prevent incorporation of damaged bases during DNA replication. Although MTH1 is non-essential in normal cells, we show that cancer cells require MTH1 activity to avoid incorporation of oxidized dNTPs, resulting in DNA damage and cell death. We validate MTH1 as an anticancer target in vivo and describe small molecules TH287 and TH588 as first-in-class nudix hydrolase family inhibitors that potently and selectively engage and inhibit the MTH1 protein in cells. Protein co-crystal structures demonstrate that the inhibitors bind in the active site of MTH1. The inhibitors cause incorporation of oxidized dNTPs in cancer cells, leading to DNA damage, cytotoxicity and therapeutic responses in patient-derived mouse xenografts. This study exemplifies the non-oncogene addiction concept for anticancer treatment and validates MTH1 as being cancer phenotypic lethal. In order to find a general treatment for cancer, this study found that MTH1 activity is essential for the survival of transformed cells, and isolated two small-molecule inhibitors of MTH1, TH287 and TH588 — in the presence of these inhibitors, damaged nucleotides are incorporated into DNA only in cancer cells, causing cytotoxicity and eliciting a beneficial response in patient-derived mouse xenograft models. MTH1 is Ras-linked target for cancer therapy Mutations in the Ras oncogene are associated with poor prognosis. It was known that overexpression of MTH1, a protein involved in preventing the incorporation of damaged bases into DNA, prevents Ras-induced senescence. In seeking to understand how damaged deoxynucleotides (dNTPs) promote cancer, Thomas Helleday and colleagues found that MTH1 activity is essential for the survival of transformed cells, and isolated two small-molecule MTH1 inhibitors, TH287 and TH588. In the presence of these hydrolase inhibitors, damaged nucleotides are incorporated into DNA only in cancer cells, causing cytotoxicity and eliciting a beneficial response in mouse xenograft cancer models. In a second study, Giulio Superti-Furga and colleagues sought to identify the target of a small molecule, SCH51344, that had been developed for use against Ras -dependent cancers and found that it inactivates MTH1. This allowed them to identify a new potent inhibitor of MTH1 that is enantiomer-selective, ( S )-crizotinib. In the presence of this drug, tumour growth is suppressed in animal models of colon cancer.
Renin–Angiotensin System Inhibition in Advanced Chronic Kidney Disease
In this randomized trial, the discontinuation of renin–angiotensin system inhibitors in patients with advanced chronic kidney disease did not lead to a significant between-group difference in the long-term rate of decline in the eGFR.
Soil enzyme activity: a brief history and biochemistry as a basis for appropriate interpretations and meta-analysis
Enzyme activity as a method for soil biochemistry and microbiology research has a long history of more than 100 years that is not widely acknowledged in terms of adherence to strict assay protocols and the interpretation of results. However, in the recent past, there is a growing lack of recognition of the historic advancements among researchers that use soil enzymology. Today, many papers are being published that use methods that either do not follow exact protocols as originally vetted in the research literature or individual labs use their own method that has not been optimized for pH, co-factors, substrate concentrations, or other conditions. This is of particular concern for fluorogenic substrates and microplate methods. Furthermore, there is a lack of understanding of the origin and location of a given enzyme being studied. Notably, regardless of the enzyme, it is too often assumed that enzyme activity equals microbial activity—which is not the case for most hydrolytic enzyme assays. Because as established by Douglas McLaren in the 1950s, a considerable amount of activity can come from catalytic enzymes stabilized in the soil matrix but that are no longer associated with viable cells (known as abiontic enzymes). In summary, today, many papers are using imperfect methods and/or misinterpret enzyme activity data that at a minimum confounds cross paper studies and meta-analysis. However, most importantly, lack of historical perspectives and ignoring strict protocols cause redundancy and fundamentally undermine the discipline and understanding of soil microbiology/biochemistry when enzymology methods are used.
Omega-3 polyunsaturated fatty acids protect against inflammation through production of LOX and CYP450 lipid mediators: relevance for major depression and for human hippocampal neurogenesis
Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can exert antidepressant, anti-inflammatory and neuroprotective properties, but the exact molecular mechanism underlying their effects is still not fully understood. We conducted both in vitro and clinical investigations to test which EPA or DHA metabolites are involved in these anti-inflammatory, neuroprotective and antidepressant effects. In vitro, we used the human hippocampal progenitor cell line HPC0A07/03C, and pre-treated cells with either EPA or DHA, followed by interleukin 1beta (IL1β), IL6 and interferon-alpha (IFN-α). Both EPA and DHA prevented the reduction in neurogenesis and the increase in apoptosis induced by these cytokines; moreover, these effects were mediated by the lipoxygenase (LOX) and cytochrome P450 (CYP450) EPA/DHA metabolites, 5-hydroxyeicosapentaenoic acid (HEPE), 4-hydroxydocosahexaenoic acid (HDHA), 18-HEPE, 20-HDHA, 17(18)-epoxyeicosatetraenoic acid (EpETE) and 19(20)-epoxydocosapentaenoic acid (EpDPA), detected here for the first time in human hippocampal neurones using mass spectrometry lipidomics of the supernatant. In fact, like EPA/DHA, co-treatment with these metabolites prevented cytokines-induced reduction in neurogenesis and apoptosis. Moreover, co-treatment with 17(18)-EpETE and 19(20)-EpDPA and the soluble epoxide hydroxylase (sEH) inhibitor, TPPU (which prevents their conversion into dihydroxyeicosatetraenoic acid (DiHETE)/ dihydroxydocosapentaenoic acid (DiHDPA) metabolites) further enhanced their neurogenic and anti-apoptotic effects. Interestingly, these findings were replicated in a sample of n = 22 patients with a DSM-IV Major Depressive Disorder, randomly assigned to treatment with either EPA (3.0 g/day) or DHA (1.4 g/day) for 12 weeks, with exactly the same LOX and CYP450 lipid metabolites increased in the plasma of these patients following treatment with their precursor, EPA or DHA, and some evidence that higher levels of these metabolites were correlated with less severe depressive symptoms. Overall, our study provides the first evidence for the relevance of LOX- and CYP450-derived EPA/DHA bioactive lipid metabolites as neuroprotective molecular targets for human hippocampal neurogenesis and depression, and highlights the importance of sEH inhibitors as potential therapeutic strategy for patients suffering from depressive symptoms.
Efficacy and safety of JNJ-42165279, a fatty acid amide hydrolase inhibitor, in adolescents and adults with autism spectrum disorder: a randomized, phase 2, placebo-controlled study
JNJ-42165279, a highly selective and orally bioavailable fatty acid amide (FAA) hydrolase inhibitor, was evaluated for efficacy and safety in adolescents and adults with autism spectrum disorder (ASD) in this phase 2, double-blind, placebo-controlled, multicenter study (NCT03664232). Participants aged 13–35 years, with a diagnosis of ASD (Diagnostic and Statistical Manual of Mental Disorders, 5th edition; Autism Diagnostic Observation Schedule, 2nd edition) were randomized (1:1) to 12 weeks of treatment with JNJ-42165279 (25 mg, twice-daily) or placebo. Primary endpoints were the change in the Autism Behavior Inventory (ABI) Core Domain (ABI-CD), ABI-Social Communication (ABI-SC), and ABI-Repetitive/Restrictive Behavior (ABI-RB) scores from baseline to day 85. Of the 61 participants (16 female, 45 male) included in the efficacy analyses, 53 (87%) completed the double-blind treatment. At day 85, the JNJ-42165279 group did not show a statistically significant reduction in ASD symptoms versus placebo, as assessed with ABI-CD ( p  = 0.284), ABI-SC ( p  = 0.290), and ABI-RB ( p  = 0.231). However, the following secondary outcomes exhibited small to moderate changes directionally favoring JNJ-42165279: Social Responsiveness Scale 2 (SRS, p  = 0.064), Repetitive Behavior Scale-Revised (RBS-R, p  = 0.006), Zarit Burden Interview short version (ZBI, p  = 0.063), Child Adolescent Symptom Inventory-Anxiety (CASI-Anx, p  = 0.048), and Caregiver Global Impression of Severity ( p  = 0.075). Notably, versus placebo, JNJ-42165279-treated participants showed increased concentrations of FAAs throughout the treatment period, with those achieving elevated concentrations experiencing the greatest reduction in the SRS total score at day 85. JNJ-42165279 demonstrated an acceptable safety profile. Although primary endpoints were not met, JNJ-42165279 may have a therapeutic effect on certain aspects of core ASD symptoms.