Enzyme Cytochrome Research Articles

Unraveling the Impact of Drug Metabolism on Tamoxifen Response in Breast Cancer.

The selective estrogen receptor modulator tamoxifen is a mainstay of endocrine breast cancer therapy. However, the clinical response rates of tamoxifen are inferior to those of aromatase inhibitors, which may be partially explained by variable drug exposure due to the pharmacogenetics of the drug-metabolizing enzyme cytochrome P450 (CYP) 2D6. Clinical trials investigating the association between CYP2D6 impairment and tamoxifen outcomes have yielded conflicting results. The results of a comprehensive meta-analysis of 33 single-center tamoxifen trials reported here address this inconsistency by adjusting for two biases that may affect the validity of previous association studies: allele coverage of CYP2D6 genotyping and loss of heterozygosity of the CYP2D6 locus in tumor-derived DNA. After adjustment for bias, meta-analyses show significantly reduced study heterogeneity and a higher risk of recurrence or death in patients with impaired CYP2D6 metabolism compared with those with normal activity. These data may support the use of pharmacogenetics-guided tamoxifen therapy to improve outcomes in patients with CYP2D6-compromised breast cancer. Prospective studies should be considered. See related article by MacLehose et al., p. 224.

Effects of Environmentally Relevant Concentrations of Roundup on Oxidative-Nitrative Stress, Cellular Apoptosis, Prooxidant-Antioxidant Homeostasis, Renin andCYP1A Expressions in Goldfish: Molecular Mechanisms Underlying Kidney Damage During Roundup Exposure.

Roundup is one of the most widely used glyphosate-based harmful herbicides in the United States as well as globally, which poses a severe risk for terrestrial and aquatic organisms. In order to identify the detrimental effects of Roundup exposure in aquatic organisms, we investigated the environmentally relevant concentrations of Roundup exposure (low dose: 0.5 μg/L and high dose: 5.0 μg/L for 2 weeks) on renin expression, oxidative-nitrative stress biomarkers (e.g., 2,4-dinitrophenol, DNP; and 3-nitrotyrosine protein, NTP), prooxidant-antioxidant enzymes expressions (e.g., superoxide dismutase, SOD; and catalase, CAT), cellular apoptosis, and cytochrome P450 1A (CYP1A) mRNA levels in the kidneys of goldfish (Carassius auratus). Histopathological and in situ TUNEL analyses showed widespread tissue disruption (e.g., bowman's capsule shrinkage, melanin pigment formation, etc.) and induced apoptotic nuclei in the kidneys of goldfish. Immunohistochemical and quantitative real-time PCR (qRT-PCR) analyses showed a significant (p < 0.05) increase in the expression of renin, DNP, NTP, SOD, and CAT, as well as CYP1A mRNA levels in the kidneys of fish exposed to Roundup. These results suggest that environmentally relevant concentrations of Roundup disrupt kidney architecture by inducing oxidative-nitrative stress, cellular apoptosis, and change in osmoregulatory enzymes (i.e., renin) and prooxidant-antioxidant systems in the kidneys of teleost fishes.

EFFECTIVENESS OF ANTHOCYANIN AS A HEPATOPROTECTOR: A SYSTEMATIC LITERATURE REVIEW

Exposure to free radicals can cause hepatotoxicity in liver cells. Hepatoprotectors are needed to prevent free radicals. The flavonoid group anthocyanin compounds, which give many plants purple, blue, and red colors, have antioxidant activity as hepatoprotectors. This study uses a systematic literature review to review the effectiveness of various plants containing anthocyanins as hepatoprotectors. Articles were searched using Google Scholar, PubMed, and NCBI with keywords such as "Anthocyanin compounds and Hepatoprotective effects" that met the inclusion and exclusion criteria. The results obtained from 7 review articles show that several plants contain anthocyanins, such as bilberry and blackberry, Rosella, purple cabbage, butterfly pea flower, Aronia melanocarpa Elliot (AMA), red cabbage, and radish. The mechanisms in plants containing anthocyanins as hepatoprotective include antioxidant activity, inhibition of cytochrome enzymes, inhibition of inflammation, protein expression, and modulation of the apoptotic signal pathway. This review concludes that plants containing anthocyanins are effective as natural hepatoprotectors with various mechanisms.

Aloe arborescens Standardized Glycosidic Fraction Suppresses Hepatocarcinoma by Modulating TIMP1, MMP9 Genes Expression, and Inflammation/Ki67/TGFβ1 Pathway.

(1) Background and aim: Aloe arborescens Mill. (A. arborescens) is one of the most widely distributed species in the genus Aloe and has garnered widespread recognition for its anticancer properties. However, the molecular mechanisms underlying these activities have not yet been fully elucidated. This study aimed to explore the effects of the plant polar glycosidic fraction (AAG) on hepatocellular carcinoma (HCC) in an invivo model induced by diethylnitrosamine (DEN). (2) Experimental procedure: The fraction was standardized using HPLC-PDA-MS/MS fingerprinting, and two distinct intragastric AAG dose regimens were examined (10 and 20 mg/kg) in combination with DEN 200 mg/kg. Serum alpha-fetoprotein (AFP), gamma-glutamyl transferase (γ-GGT), glutathione S-transferase placental (GST-P), mRNA expression of metabolic cytochrome enzymes (CYP1A3 and CYP2B2), inflammatory genes (nuclear factor kappa-B p65 subunit; NF-κB p65), metalloproteases 9 (MMP9), tissue inhibitors of metalloproteases (TIMP1), transforming growth factor beta 1 (TGFβ1), and histological features were assessed. (3) Key results and conclusions and implications: AAG was characterized by five major secondary metabolites: saponins, chromones, anthraquinone, and triterpenes. The fraction reduced hepatic malignancy characteristics by diminishing the size and number of altered foci and lowering hepatic cancer biomarkers, such as γ-GGT, AFP, and GST-positive foci. It also reduced the mRNA levels of CYP1A3 and CYP2B2, NF-κB p65, and MMP9, hepatic Ki-67, and TGFβ1 while upregulating TIMP1 levels. This study revealed that AAG exhibited a marked suppressive effect on HCC cell proliferation, displaying a range of mechanistic actions, including decreasing the metabolic activation of cytochrome enzymes, which consequently reduced the production of reactive oxygen species and other genes implicated in cancer development. AAG could be a significant therapeutic candidate for patients diagnosed with hepatocarcinoma.

Use of Intramolecular Quinol Redox Couples to Facilitate the Catalytic Transformation of O2 and O2-Derived Species.

ConspectusThe redox reactivity of transition metal centers can be augmented by nearby redox-active inorganic or organic moieties. In some cases, these functional groups can even allow a metal center to participate in reactions that were previously inaccessible to both the metal center and the functional group by themselves. Our research groups have been synthesizing and characterizing coordination complexes with polydentate quinol-containing ligands. Quinol is capable of being reversibly oxidized by either one or two electrons to semiquinone or para-quinone, respectively. Functionally, quinol behaves much differently than phenol, even though the pKa values of the first O-H bonds are nearly identical.The redox activity of the quinol in the polydentate ligand can augment the abilities of bound redox-active metals to catalyze the dismutation of O2-• and H2O2. These complexes can thereby act as high-performing functional mimics of superoxide dismutase (SOD) and catalase (CAT) enzymes, which exclusively use redox-active metals to transfer electrons to and from these reactive oxygen species (ROS). The quinols augment the activity of redox-active metals by stabilizing higher-valent metal species, providing alternative redox partners for the oxidation and reduction of reactive oxygen species, and protecting the catalyst from destructive side reactions. The covalently attached quinols can even enable redox-inactive Zn(II) to catalyze the degradation of ROS. With the Zn(II)-containing SOD and CAT mimics, the organic redox couple entirely substitutes for the inorganic redox couples used by the enzymes. The ligand structure modulates the antioxidant activity, and thus far, we have found that compounds that have poor or negligible SOD activity can nonetheless behave as efficient CAT mimics.Quinol-containing ligands have also been used to prepare electrocatalysts for dioxygen reduction, functionally mimicking the enzyme cytochrome c oxidase. The installation of quinols can boost electrocatalytic activity and even enable otherwise inactive ligand frameworks to support electrocatalysis. The quinols can also shift the product selectivity of O2 reduction from H2O2 to H2O without markedly increasing the effective overpotential. Distinct control of the coordination environment around the metal center allows the most successful of these catalysts to use economic and naturally abundant first-row transition metals such as iron and cobalt to selectively reduce O2 to H2O at low effective overpotentials. With iron, we have found that the electrocatalysts can enter the catalytic cycle as either an Fe(II) or Fe(III) species with no difference in turnover frequency. The entry point to the cycle, however, has a marked impact on the effective overpotential, with the Fe(III) species thus far being more efficient.

Innovative Personalized Medicine for Immunosuppressive Drugs Based on Novel Control Theory of Pharmacokinetics

Tacrolimus is widely recognized as an anti-rejection agent due to its immunosuppressive characteristics. It binds to the immunophilin FK506-binding protein (FKBP) and thus to calcineurin, and inhibits its activity. Tacrolimus' therapeutic concentration range in blood is narrow, and its pharmacokinetics are highly variable among individuals. First, because tacrolimus primarily distributes to red blood cells (RBCs), anemia and blood transfusions can cause fluctuations in tacrolimus blood concentrations. Variations in blood tacrolimus concentration significantly correlated with variations in RBC count, hemoglobin level, and hematocrit value, but not with variations in white blood cell or platelet counts. Interestingly, FKBP played an important role in tacrolimus distribution to RBCs. The effects of intracellular and extracellular FKBP levels on RBC distribution of tacrolimus in circulating blood were substantial. Secondly, proteins affecting pharmacokinetics can differ at the genetic level in their expression and functional potency. Genetic polymorphisms that influence tacrolimus pharmacokinetics have been reported. A polymorphism in the gene encoding the metabolic enzyme cytochrome P450 (CYP) 3A5 is a particularly influential factor affecting tacrolimus pharmacokinetics in Japanese patients. CYP3A5 polymorphisms correlated with individual differences in tacrolimus blood concentration changes after starting continuous infusion in allogeneic hematopoietic stem cell transplantation (HSCT) recipients. In addition, CYP3A5*3 polymorphism also correlated with differences in the frequency of acute graft-versus-host disease (GVHD) development in allogeneic HSCT recipients.

Dopamine Transporter and CYP2D6 Gene Relationships with Attention-Deficit/Hyperactivity Disorder Treatment Response in the Methylphenidate and Atomoxetine Crossover Study.

Background: Few biological or clinical predictors guide medication selection and/or dosing for attention-deficit/hyperactivity disorder (ADHD). Accumulating data suggest that genetic factors may contribute to clinically relevant pharmacodynamic (e.g., dopamine transporter-SLC6A3 also commonly known as DAT1) or pharmacokinetic (e.g., the drug metabolizing enzyme Cytochrome P450 2D6 CYP2D6) effects of methylphenidate (stimulant) and atomoxetine (non-stimulant), which are commonly prescribed medications. This is the first study of youth with ADHD exposed to both medications examining the clinical relevance of genetic variation on treatment response. Methods: Genetic variations in DAT1 and CYP2D6 were examined to determine how they modified time relationships with changes in ADHD symptoms over a 4-week period in 199 youth participating in a double-blind crossover study following a stepped titration dose optimization protocol. Results: Our results identified trends in the modification effect from CYP2D6 phenotype and the time-response relationship between ADHD total symptoms for both medications (atomoxetine [ATX]: p = 0.058, Methylphenidate [MPH]: p = 0.044). There was also a trend for the DAT1 3' untranslated region (UTR) variable number of tandem repeat (VNTR) genotype to modify dose relationships with ADHD-RS total scores for atomoxetine (p = 0.029). Participants with DAT1 9/10 repeat genotypes had a more rapid dose-response to ATX compared to 10/10, while those with 9/9 genotypes did not respond as doses were increased. Regardless of genotype, ADHD symptoms and doses were similar across CYP2D6 metabolizer groups after 4 weeks of treatment. Conclusions: Most children with ADHD who were CYP2D6 normal metabolizers or had DAT1 10/10 or 9/10 genotypes responded well to both medications. While we observed some statistically significant effects of CYP2D6 and DAT1 with treatment response over time, our data indicate that genotyping for clinical purposes may have limited utility to guide treatment decisions for ATX or MPH because both medications were generally effective in the studied cohort after 3 weeks of titration to higher doses. The potential DAT1 association with ATX treatment is a novel finding, consistent with prior reports suggesting an association of the DAT1 in 9/9 genotypes with lower responsive rates to treatment at low and moderate doses.

Potential drug interaction after withdrawal of nirmatrelvir-ritonavir in hospitalized patients with COVID-19 infection.

Nirmatrelvir-ritonavir is effective in the treatment of SARS-CoV-2 infection. It can cause drug‒drug interactions (DDIs), even several days after withdrawal, due to irreversible inhibition of the cytochrome enzyme. Hospitalized patients diagnosed with COVID-19 infection and treated with nirmatrelvir-ritonavir were retrospectively included according to preset criteria. Personal information, as well as drug use, were obtained from the hospital information system. Potential DDIs were screened and classified according to three databases (FDA fact sheet, University of Liverpool Drug Interactions resources and Lexicomp). A total of 332 hospitalized patients with COVID-19 infection who received nirmatrelvir-ritonavir treatment were included in this study. The prevalence of potential DDI risk after withdrawal of nirmatrelvir-ritonavir in hospitalized patients was 57.2%. Most patients resumed potentially interacting medications on the first day of nirmatrelvir-ritonavir withdrawal, and those drugs with DDI risk at the avoidance level mainly included dexamethasone and rivaroxaban, whereas drugs at the caution level mainly included lidocaine. The prevalence of potential DDI risk after withdrawal of nirmatlevir-ritonavir was high and should be given more attention.

Leptin fragment modulates the stimulatory effects of chorionic gonadotropin on testicular steroidogenesis in a model of diet-induced obesity in rats

Leptin, secreted by adipose tissue, indirectly stimulates the activity of GnRH-producing neurons of the hypothalamus and thus regulates the functional activity of the hypothalamic-pituitary-testicular (HPT) axis. As is known, the obesity is accompanied by systemic hyperleptinemia and impaired leptin transport in the central nervous system, which limits the use of full-length leptin as a drug. It was previously shown that intranasally administered leptin fragment MA-[D-Leu4]-OB3 (LF) enhances the steroidogenic effect of human chorionic gonadotropin (hCG) in rats fed a standard diet. An even more urgent task is to assess its effect on testicular steroidogenesis in conditions of obesity, which reduces reproductive functions in men. The aim of the work was to study the ability of LF (200 μg/kg, intranasally, 3 days) to modulate the effect of hCG (10 IU/rat, subcutaneously, once) on testicular steroidogenesis in rats with obesity induced by a high-fat/high-carbohydrate diet (HFHCD), and also to evaluate influence of the GnRH receptor antagonist cetrorelix (ANT, 75 µg/kg, subcutaneously, 3 days) on the effects of LF. Male Wistar rats were used for the study and received HFHCD for 20 weeks. In obese rats, the level of the luteinizing hormone (LH) receptor in the testes was reduced and the expression of the Cyp11a1 gene, encoding the steroidogenic enzyme cytochrome P450scc, was compensatory increased. LF administration enhanced the effect of hCG on the testosterone level in the blood and the expression of the Star gene, encoding the cholesterol transport protein StAR, which indicates the ability of LF to positively modulate the activity of the HPT axis in obesity. Co-administration of ANT and LF, on the contrary, reduced the stimulating effect of hCG on testosterone levels and Star gene expression, which may be due to the testicular effects of LF. Our data indicate the ability of LF to influence various components of the male gonadal axis under conditions of diet-induced obesity.

Hypertensive Nephropathy Changes the Expression of Drug-Metabolizing Enzymes and Transporters in Spontaneously Hypertensive Rat Liver and Kidney.

Hypertensive nephropathy (HN) has become one of the main causes of end-stage renal disease. Drug combination therapy is a common clinical treatment for HN. However, the impact of HN on drug-metabolizing enzymes and transporters, which may lead to drug-drug interactions (DDIs) and even trigger toxic side effects, remains unclear. The aim of this study was to investigate changes in major drug-metabolizing enzymes and transporters in the liver and kidney of HN rats to improve the scientific foundations for the clinical treatment of HN. Spontaneously hypertensive rats (SHRs) were used as an animal HN model because their hypertension is similar to that of humans. Wistar-Kyoto rats (WKYs) were used as the control group. Body weight, blood pressure, hematoxylin-eosin (HE) staining and biochemical analysis were performed to evaluate whether the HN model was successfully constructed. Quantitative real-time polymerase chain reaction (PCR) and western blotting were used to evaluate the mRNA and protein expression of drug-metabolizing enzymes, transporters and related nuclear transcription factors. In HN rats, the mRNA expression of the drug-metabolizing enzymes cytochrome P450 (Cyp) 2b1, Cyp2c11, Cyp3a1 and Cyp7a1 was significantly upregulated. The protein level of CYP3A1 was consistent with its mRNA expression. Interestingly, the mRNA expression of the hepatic transporters organic cation transporter (Oct) 1, Oct2, organic anion transporter (Oat) 1, Oat2, multidrug resistant protein (Mrp) 2, multidrug resistance (Mdr) 1, organic anion transporting polypeptide (Oatp) 1b2 and na+/taurocholate cotransporting polypeptide (Ntcp) was also markedly upregulated. This may be directly influenced by the upregulation of the expression of the nuclear receptors farnesoid X receptor (Fxr), pregnane X receptor (Pxr), liver X-activated receptor (Lxr) and constitutive androstane receptor (Car). In the kidney of HN rats, the mRNA level of the drug-metabolizing enzyme Cyp2b1 significantly increased, while levels of Cyp1a1, Cyp2c11, Cyp3a1 and Cyp3a2 did not significantly change. The mRNA expression of the transporters multidrug and toxin extrusion (Mate) 1 and Mrp2 was obviously increased but was markedly depressed for peptide transporters (Pept) 1 and Pept2. These changes may be related to the cross effects of Pxr, Fxr and Car in kidney. HN pathological status can alter the expression of drug-metabolizing enzymes and transporters in the liver and kidney to varying degrees, thus affecting the disposition of substrate drugs in vivo. This suggests that to avoid potential risks, caution should be exercised when administering combination therapy for HN treatment.

Characterization of a novel IGFBP-2 transcript in the ovarian granulosa cells of chicken follicles: mRNA expression, function and effect of reproductive hormones and IGF1

Insulin-like growth factor binding protein-2 (IGFBP-2), a binding protein of insulin-like growth factor (IGF) system, regulates the activity of IGFs and also influences cellular function with endogenous activity. In mammals, IGFBP-2 is reported to affect ovarian follicle development and steroidogenesis; however, its role in the chicken ovary is unknown. In this study, we investigated the mRNA expression and function of a novel IGFBP-2 transcript and the effect of reproductive hormones and insulin-like growth factor 1 (IGF1) on its expression in the ovarian granulosa cells of chicken follicles. The mRNA expression of IGFBP-2 was significantly increased in granulosa cells after follicle selection and was higher in hierarchical granulosa cells (Post-GCs) than in pre-hierarchical granulosa cells (Pre-GCs). IGFBP-2 promoted the proliferation and inhibited the apoptosis of both Pre-GCs and Post-GCs, enhanced the mRNA expression of genes involved in progesterone (P4) synthesis in Pre-GCs. However, in Post-GCs, IGFBP-2 inhibited the mRNA expression of these genes and suppressed P4 secretion. The mRNA expression of IGFBP-2 was inhibited by estradiol (E2) and follicle-stimulating hormone (FSH), but enhanced by P4 in Pre-GCs. In Post-GCs, FSH and IGF1 stimulated the mRNA expression of IGFBP-2 synergistically. Knockdown of IGFBP-2 attenuated the stimulatory effect of IGF1 on the mRNA expression of the side chain cleavage enzyme cytochrome P450 family 11 subfamily A member 1 (CYP11A1). These findings indicate that IGFBP-2 is regulated by FSH and IGF1, exerts different functions in Pre-GCs and Post-GCs in regulating IGF1 and plays an important role in chicken follicle development by affecting granulosa cell proliferation and P4 synthesis.

Nephro- and Cardiotoxic Effects of Etoricoxib: Insights into Arachidonic Acid Metabolism and Beta-Adrenergic Receptor Expression in Experimental Mice.

Background: Etoricoxib is a widely used anti-inflammatory drug, but its safety profile concerning cardiovascular and renal health remains inadequately explored. This study aimed to assess the nephro- and cardiotoxic effects of etoricoxib in a murine model, with a focus on its impact on arachidonic acid-metabolizing enzymes and beta-adrenergic receptors associated with drug-induced toxicity. Methods: Thirty-five BALB/C mice were randomly assigned to five groups: control, low-dose etoricoxib, high-dose etoricoxib, low-dose celecoxib, and high-dose celecoxib (a well-known nephro- and cardiotoxic NSAID). The treatments were administered for 28 days, after which hearts and kidneys were excised for physical and histopathological analysis, and the expression of arachidonic acid-metabolizing enzymes (cytochrome P450s, lipoxygenases, cyclooxygenases) and beta-1 adrenergic receptor (adrb1) and angiotensin-converting enzyme (ace2) genes were quantified using quantitative reverse transcription PCR (qRT-PCR). Results: Etoricoxib administration resulted in dose-dependent nephro- and cardiotoxic effects. Renal histology revealed glomerular atrophy or hypertrophy and significant damage to the proximal and distal convoluted tubules, including epithelial flattening, cytoplasmic vacuolation, and luminal widening. Cardiac analysis showed disorganized muscle fibers and hyaline degeneration. These changes were associated with altered gene expression: the downregulation of cox2, cyp1a1, and cyp2c29 in the kidneys and the upregulation of cyp4a12, cox2, and adrb1, along with the downregulation of cyp2c29 and ace2 in the heart. Conclusions: Etoricoxib induces nephro- and cardiotoxicity, marked by alterations in arachidonic acid metabolism and beta-adrenergic signaling pathways. The drug affects the expression of arachidonic acid-metabolizing enzymes and adrb1 in the heart while downregulating cox2 and other related enzymes in the kidneys. These findings underscore the need for caution when prescribing etoricoxib, particularly in patients with pre-existing renal or cardiac conditions.

The Second Protonation in the Bio-Catalytic Cycles of the Enzymes Cytochrome P450 and Superoxide Reductase

The Second Protonation in the Bio-Catalytic Cycles of the Enzymes Cytochrome P450 and Superoxide Reductase

Effects of α-olefin sulfonate (AOS) on Tubifex tubifex: toxicodynamic-toxicokinetic inferences from the general unified threshold (GUTS) model, biomarker responses and molecular docking predictions.

We investigated the potential ecological risks and harm to aquatic organisms posed by anionic surfactants such as α-olefin sulfonate (AOS), which are commonly found in industrial and consumer products, including detergents. This study assessed acute (96-h) and subchronic (14-day) responses using antioxidant activity, protein levels, and histopathological changes in Tubifex tubifex exposed to different AOS concentrations (10% of the LC50, 20% of the LC50, and a control). Molecular docking was used to investigate the potential interactions between the key stress biomarker enzymes (superoxide dismutase, catalase, and cytochrome c oxidase) of Tubifex tubifex. Acute AOS exposure showed a concentration-dependent decrease in survival, and the general unified threshold (GUTS) model revealed that survivorship is linked to individual response patterns rather than random (stochastic) fluctuations. The GUTS model also revealed dose-dependent toxicity patterns in Tubifex tubifex exposed to α-olefin sulfonate (AOS), with adaptive mechanisms at lower concentrations but significant increases in mortality beyond a certain threshold, emphasizing the role of the AOS concentration in shaping its toxicological impact. Exposure to AOS disrupted antioxidant activity, inducing oxidative stress, with GST and GPx showing positive associations with surfactant concentration and increased lipid peroxidation (elevated MDA levels); moreover, AOS exposure decreased protein concentration, signifying disturbances in vital cellular processes. Histopathological examinations revealed various tissue-level alterations, including cellular vacuolation, cytoplasmic swelling, inflammation, necrosis, and apoptosis. Molecular docking analysis demonstrated interactions between AOS and enzymes (-catalase, superoxide dismutase, and cytochrome c oxidase) in Tubifex tubifex, including hydrophobic and hydrogen bond interactions, with the potential to disrupt enzyme structures and activities, leading to cellular process disruptions, oxidative stress, and tissue damage. According to the species sensitivity distribution (SSD), the difference in toxicity between Tilapia melanopleura (higher sensitivity) and Daphnia magna (low sensitivity) to AOS suggests distinct toxicokinetic and toxicodynamic mechanisms attributable to more complex physiology in Tilapia and efficient detoxification in Daphnia due to its smaller size.

Enhancing Performances of Enzyme/Metal-Organic Polyhedra Composites by Mixed-Protein Co-Immobilization.

Protein immobilization using water-soluble ionic metal-organic polyhedra (MOPs) acting as porous spacers has recently been demonstrated as a potent strategy for the preparation of biocatalysts. In this article, we describe a mixed-protein approach to achieve biocomposites with adjustable enzyme contents and excellent immobilization efficiencies, in a systematic and well-controlled manner. Self-assembly of either cationic or anionic MOPs with bovine serum albumin or egg white lysozyme combined with enzymes (alkaline phosphatase, laccase or cytochrome c) led to solid-state catalysts with a high retention of enzyme activity. Furthermore, for all these systems, the dilution of enzymes within the solid-state composite led to noticeably improved catalytic performances, with both higher specific activity and affinity for substrate.

Impact of steroid hormone levels on estradiol-mediated regulation of cytochrome P450 2B6 compared to 1B1 in breast cancer cells.

Pharmacogenetic variants of the steroid hormone-metabolizing enzyme cytochrome P450 2B6 (CYP2B6) were reported to be associated with breast cancer (BC) risk and prognosis. CYP2B6 expression is inducible by estradiol (E2) but induction was demonstrated only under steroid hormone-deprived medium conditions. Physiological conditions, however, even under endocrinological BC treatment, do not correspond to complete steroid hormone depletion. The aim of this study was to investigate the E2-mediated CYP2B6 and CYP1B1 regulation under various steroid hormone conditions, including physiological concentrations, in human oestrogen receptor positive (T47D, MCF-7) and negative (MDA-MB-231) BC cell lines. We confirm that steroid-deprived pre-cultivation led to CYP2B6 upregulation in T47D, but not in MCF-7. However, when pre-cultivated with steroid-containing medium CYP2B6 was downregulated in T47D and MCF-7, while the addition of physiological E2 concentrations to steroid-deprived medium resulted in a downregulation in T47D. In contrast, CYP1B1 was never downregulated in any culture condition. Thus, we show that E2-mediated CYP2B6 regulation in BC cells depends on steroid hormone exposure in a cell line-specific manner. Our data indicates the importance of being careful with conclusions drawn from CYP2B6 induction findings in vitro, as we demonstrate potential influences of hormonal changes on CYP2B6 expression, which could impact steroid hormone homeostasis and, consequently, BC risk.

A Physiologically-Based Pharmacokinetic Simulation to Evaluate Approaches to Mitigate Efavirenz-Induced Decrease in Levonorgestrel Exposure with a Contraceptive Implant.

Background: Levonorgestrel implant is a highly effective hormonal contraceptive, but its efficacy may be compromised when used with cytochrome enzyme inducers such as efavirenz. The primary aim of this study was to evaluate methods of mitigating the drug interaction. Methods: Using a physiologically-based pharmacokinetic (PBPK) model for levonorgestrel that we developed within the Simcyp® program, we evaluated a higher dose of levonorgestrel implant, a lower dose of efavirenz, and the combination of both, as possible methods to mitigate the interaction. In addition, we investigated the impact on levonorgestrel total and unbound concentrations of other events likely to be associated with efavirenz coadministration: changes in plasma protein binding of levonorgestrel (as with displacement) and high variability of efavirenz exposure (as with genetic polymorphism of its metabolism). The range of fraction unbound tested was 0.6% to 2.6%, and the range of efavirenz exposure ranged from the equivalent of 200 mg to 4800 mg doses. Results: Levonorgestrel plasma concentrations at any given time with a standard 150 mg implant dose are predicted to be approximately 68% of those of control when given with efavirenz 600 mg and 72% of control with efavirenz 400 mg. With double-dose levonorgestrel, the predictions are 136% and 145% of control, respectively. A decrease in levonorgestrel plasma protein binding is predicted to primarily decrease total levonorgestrel plasma concentrations, whereas higher efavirenz exposure is predicted to decrease total and unbound concentrations. Conclusions: Simulations suggest that doubling the dose of levonorgestrel, particularly in combination with 400 mg daily efavirenz, may mitigate the drug interaction. Changes in levonorgestrel plasma protein binding and efavirenz genetic polymorphism may help explain differences between model predictions and clinical data but need to be studied further.

Reversal of hepatic accumulation of nordeoxycholic acid underlines the beneficial effects of cholestyramine on alcohol-associated liver disease in mice.

Dysregulation of bile acids (BAs) has been reported in alcohol-associated liver disease. However, the causal relationship between BA dyshomeostasis and alcohol-associated liver disease remains unclear. The study aimed to determine whether correcting BA perturbation protects against alcohol-associated liver disease and elucidate the underlying mechanism. BA sequestrant cholestyramine (CTM) was administered to C57BL/6J mice fed alcohol for 8 weeks to assess its protective effect and explore potential BA targets. The causal relationship between identified BA metabolite and cellular damage was examined in hepatocytes, with further manipulation of the detoxifying enzyme cytochrome p450 3A11. The toxicity of the BA metabolite was further validated in mice in an acute study. We found that CTM effectively reversed hepatic BA accumulation, leading to a reversal of alcohol-induced hepatic inflammation, cell death, endoplasmic reticulum stress, and autophagy dysfunction. Specifically, nordeoxycholic acid (NorDCA), a hydrophobic BA metabolite, was identified as predominantly upregulated by alcohol and reduced by CTM. Hepatic cytochrome p450 3A11 expression was in parallel with NorDCA levels, being upregulated by alcohol and reduced by CTM. Moreover, CTM reversed alcohol-induced gut barrier disruption and endotoxin translocation. Mechanistically, NorDCA was implicated in causing endoplasmic reticulum stress, suppressing autophagy flux, and inducing cell injury, and such deleterious effects could be mitigated by cytochrome p450 3A11 overexpression. Acute NorDCA administration in mice significantly induced hepatic inflammation and injury along with disrupting gut barrier integrity, leading to subsequent endotoxemia. Our study demonstrated that CTM treatment effectively reversed alcohol-induced liver injury in mice. The beneficial effects of BA sequestrant involve lowering toxic NorDCA levels. NorDCA not only worsens hepatic endoplasmic reticulum stress and inhibits autophagy but also mediates gut barrier disruption and systemic translocation of pathogen-associated molecular patterns in mice.

Prospective Trial on the Pharmacokinetics of Clopidogrel in Hemodialysis Patients

IntroductionPatients undergoing hemodialysis (HDP) exhibit extensive cardiovascular risk. The widely prescribed anti-platelet agent clopidogrel is metabolically activated by cytochrome enzymes, which may be impaired by uremia and chronic low-grade inflammation, typically present in HDP. We conducted a prospective multicenter study to investigate the pharmacokinetics and pharmacodynamics of clopidogrel in HDP and healthy volunteers (HV). MethodsWe enrolled HDP receiving long-term clopidogrel (75mg) and pantoprazole treatment (40 mg). HV received a loading dose of 300 mg clopidogrel, followed by 75 mg once daily. Pantoprazole, a substrate and probe drug of CYP2C19, was administered intravenously (40 mg). Plasma concentrations were quantified by mass spectrometry. Pharmacokinetics were calculated, and a population pharmacokinetic model was developed. The primary endpoint was the maximum concentration of clopidogrel’s active metabolite (Cmax_CAM). Platelet aggregation was measured using ADP-induced whole-blood aggregometry. ResultsSeventeen HDP and 16 HV were included. Cmax_CAM was significantly lower in HDP compared to HV (median [IQR] 12.2 [4.6-23.4] vs. 24.7 [17.8-36.5] ng/mL, p=0.02). The Cmax ratio of CAM to prodrug was 8.5-fold lower in HDP, and an 82.7% reduced clopidogrel clearance, including CAM formation, was found using population pharmacokinetic modeling. ADP-induced platelet aggregation at 120 min was significantly higher in HDP than in HV (median [IQR]: 26 [14-43] vs. 12 [11-18] U, p=0.004. Pantoprazole terminal half-life was ∼1.7-fold higher in HDPs compared to HVs. ConclusionOur data demonstrate an altered metabolism of clopidogrel in HDP in the context of lower CYP2C19 activity, with potential implications for other substances metabolized by this enzyme.

Exploring the interplay between Alzheimer's disease and COVID-19: Insights into cognitive impairment and drug interactions

Alzheimers disease (AD) is a severe well-known cognitive disease, and it is also the most worldwide cause of dementia. Studies have shown that AD may have some interactions with the coronavirus disease 2019 (COVID-19) in some particular areas. This paper aims to figure out the potential associations how one causes the interplay of another, whether directly or indirectly. In addition, the paper provides a comprehensive mechanism underlying cognitive impairment also known as brain fog of COVID-19, including the effects on neurons and glial cells by persistent elevation of the chemokine CCL11. Then the paper provides drug-drug interaction with metabolized by same cytochrome enzymes lead to major changes in the pharmacology of treatments. Finally, the paper concludes the points mentioned about the associations between COVID-19 and AD then suggests the direction of the future studies.