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Cytochrome P450 3A4 (CYP3A4) is a crucial enzyme involved in the Phase I metabolism of numerous medications used in clinical practice. Its potential significance in pediatric pharmacotherapy is underscored by the unique metabolic profile of children, which differs markedly from adults, especially in neonates, infants, and young children due to developmental changes in enzyme activity. This review explores the critical role of CYP3A4 in the metabolism of drugs used in the pediatric population, with a particular focus on combination drug therapies. Given the high potential for drug-drug interactions in combination therapies, understanding the modulation of CYP3A4 activity is essential for optimizing therapeutic outcomes and minimizing adverse effects. This paper further examines the structural similarities between these medications and bergamottin, a known CYP3A4 inhibitor found in citric fruits such as grapefruit. Variability in CYP3A4 activity, influenced by genetic polymorphisms, developmental stage, and external factors, necessitates careful consideration in the prescribing and management of drugs in children. This review corroborates the need for personalized medicine approaches and enhanced pharmacovigilance to ensure the safe and effective use of CYP3A4-metabolized drugs in the pediatric population. [ABSTRACT FROM AUTHOR]

Aim: Our objective was to systematically assess the prevalence and clinical features of adverse events related to interactions between cannabinoids and psychotropic drugs through a retrospective chart review. Methodology: 1586 adverse event reports were assessed. Cases included in the analysis showed a high probability of a causal relationships between cannabinoid-psychotropic drug interactions and adverse events. Data extracted included age, sex, psychotropic drug, cannabinoid products, other medications, and the clinical outcomes and mechanisms of these interactions. Results: Cannabinoids were involved in 8% of adverse events associated with the concomitant use of psychotropic drugs and other preparations. We identified 20 reports in which side effects presented a causal relationship with the use of psychotropic drugs and cannabinoids. Preparations containing 18% or more tetrahydrocannabinol (THC), presented significant side effects with the following antidepressants: mianserine (restless legs syndrome, urogenital pain, ventricular tachycardia), mirtazapine (pancreatitis, hyperhidrosis, arthralgia), quetiapine (myocarditis, renal failure, bradycardia, sialorrhea), haloperidol (ventricular arrhythmia, prolonged QTc), aripiprazole (prolonged QTc), ventricular tachycardia) and cariprazine (stomach pain, hepatotoxicity), sertraline (ataxia, hyperactivity, coma, hallucinations, anxiety, agitation, tachycardia, panic attacks, disorientation, headache, dizziness, blurry vision, severe emesis, xerostomia, dry eyes), trazodone (disorientation, memory impairment, sedation), fluvoxamine (tachycardia, tachypnoea, dysarthria, auditory hallucinations). Two out of 20 reports (10%) analyzed in our study was related with the simultaneous use of cannabidiol (CBD) oil and sertraline. Concomitant use of those substances was associated with the adverse events in form of diarrhea, emesis, fever and severe fatigue. Conclusion: Clinicians need to closely monitor adverse events resulting from the combined use of cannabinoids and psychotropic medications. The accumulation of side effects and pharmacokinetic interactions (including CYP and p-glycoprotein inhibition) between these drugs can lead to clinically significant adverse outcomes. [ABSTRACT FROM AUTHOR]

Aims: Metamizole is quite an old drug with analgesic, antipyretic and spasmolytic properties. Recent findings have shown that it may induce several cytochrome P450 (CYP) enzymes, especially CYP3A4 and CYP2B6. The clinical relevance of these properties is uncertain. We aimed to unravel potential pharmacokinetic interactions between metamizole and the CYP3A4 substrate quetiapine. Methods: Plasma concentrations of quetiapine from a large therapeutic drug monitoring database were analysed. Two groups of 33 patients, either receiving quetiapine as a monotherapy (without CYP modulating comedications) or with concomitantly applied metamizole, were compared addressing a potential impact of metamizole on the metabolism of quetiapine being reflected in differences of plasma concentrations of quetiapine and dose‐adjusted plasma concentrations. Results: Patients comedicated with metamizole showed >50% lower plasma concentrations of quetiapine (median 45.2 ng/mL, Q1 = 15.5; Q3 = 90.5 vs. 92.0 ng/mL, Q1 = 52.3; Q3 = 203.8, P =.003). The dose‐adjusted plasma concentrations were 69% lower in the comedication group (P =.001). Subgroup analyses did not suggest a dose dependency of the metamizole effect or an influence of quetiapine formulation (immediate vs. extended release). Finally, the comedication group exhibited a significantly higher proportion of patients whose quetiapine concentrations were below the therapeutic reference range (78.8% in the metamizole group vs. 54.4% in the control group, P =.037) indicating therapeutically insufficient drug concentrations. Conclusion: The combination of metamizole and quetiapine leads to significantly lower drug concentrations of quetiapine, probably via an induction of CYP3A4. Clinicians must consider the risk of adverse drug reactions, especially treatment failure under quetiapine when adding metamizole. [ABSTRACT FROM AUTHOR]

Decades of research describe myriad redox enzymes that contain cofactors arranged in tightly packed chains facilitating rapid and controlled intra‐protein electron transfer. Many such enzymes participate in extracellular electron transfer (EET), a process which allows microorganisms to conserve energy in anoxic environments by exploiting mineral oxides and other extracellular substrates as terminal electron acceptors. In this work, we describe the properties of the triheme cytochrome PgcA from Geobacter sulfurreducens. PgcA has been shown to play an important role in EET but is unusual in containing three CXXCH heme binding motifs that are separated by repeated (PT)x motifs, suggested to enhance binding to mineral surfaces. Using a combination of structural, electrochemical, and biophysical techniques, we experimentally demonstrate that PgcA adopts numerous conformations stretching as far as 180 Å between the ends of domains I and III, without a tightly packed cofactor chain. Furthermore, we demonstrate a distinct role for its domain III as a mineral reductase that is recharged by domains I and II. These findings show PgcA to be the first of a new class of electron transfer proteins, with redox centers separated by some nanometers but tethered together by flexible linkers, facilitating electron transfer through a tethered diffusion mechanism rather than a fixed, closely packed electron transfer chain. [ABSTRACT FROM AUTHOR]

Objective: We aimed to investigate the ambiguous findings of earlier research regarding the reduction of quetiapine plasma levels when combined with lamotrigine, most likely via UDP-glucuronosyltransferase induction by lamotrigine. Methods: One thousand one hundred and fifty samples, divided into four groups of patients receiving either quetiapine immediate- (IR) or extended-release (XR) without or in combination with lamotrigine were compared regarding absolute and dose-adjusted plasma concentrations. Furthermore, samples of intra-individual controls were analyzed. Results: Patients receiving quetiapine IR in combination with lamotrigine showed 31% lower plasma (p = 0.002) and 23% lower dose-adjusted plasma concentrations (p = 0.004) compared to those receiving IR monotherapy. The proportion of patients with quetiapine plasma concentrations below the lower limit of the therapeutic reference range was 50% and 30% in the combination group and in patients receiving monotherapy, respectively (p = 0.03). However, no significant differences regarding plasma concentration (p = 0.13) and dose-adjusted plasma concentration (p = 0.42) were observed in patients with combination vs. monotherapy with the XR formulation of quetiapine. In the intra-individual controls, no trends could be identified, possibly due to insufficient number of samples (p > 0.05). Conclusions: The combination of quetiapine IR with lamotrigine is associated with significantly lower drug concentrations of quetiapine, potentially impacting quetiapine effectiveness. For quetiapine ER, a significant interaction is less likely. [ABSTRACT FROM AUTHOR]

Flavoalkaloids, a potent class of cyclin‐dependent kinase inhibitors, have undergone extensive clinical trials across various cancer types. Among them, flavopiridol, riviciclib, and voruciclib are the most advanced candidates. These molecules are lipophilic and possess functional groups conducive to both phase I and phase II metabolism in the liver. This study employs in‐silico methods to identify the potential cytochrome P450‐mediated sites of phase I metabolism (SOM) in these compounds. According to two web‐server‐based predictions, the N‐methyl group was identified as the primary SOM in these compounds, showing the highest probability score for involvement of CYP3A4. Docking studies conducted using both Glide and the induced‐fit method further confirmed N‐demethylation as a significant metabolic pathway predominantly catalyzed by CYP3A4. The distance between the N‐methyl group of the docked ligands and the iron atom of the heme ranged from 3 to 7 Å, with flavopiridol's N‐methyl group positioned closest to the heme iron at 3.16 Å. The 100 ns molecular dynamic simulations additionally validated the stability of the interaction between flavoalkaloids and the heme Fe. Similarly, the docking‐based SOM predictions matched the experimental SOM for other approved drugs. Thus, employing docking‐based SOM predictions holds potential for enhancing lead optimization efforts in future medicinal chemistry research. [ABSTRACT FROM AUTHOR]

The anthelmintic macrocyclic lactones (MLs) are the most important endectocides in modern pharmacotherapy of parasitic infections. However, during the COVID 19 pandemic, ivermectin was used in humans against infection with the SARS-CoV-2 virus in doses significantly higher than the approved antiparasitic doses. This kind of application was created solely on the basis of in vitro tests, and is not officially approved in any country in the world. Therefore, we conducted a study on rats treated orally with 0.6, 1.2, 2.4 and 4.8 mg/kg of ivermectin for 5 days. Based on our investigation, ivermectin at the doses used in humans against the SARS-Co-2 virus (3, 6, 12 and 24 times higher than the antiparasitic dose 0.2mg/kg), causes changes in red blood cell counts and increases the levels of liver enzymes without visible clinical symptoms. Histopathological changes were recorded in the liver, kidneys and testicles of rats, and the highest dose tested led to bleeding in the brain tissue. Obviously, ivermectin somewhat increases concentration of the enzyme P-450 isoform 3A4, whose substrate it is, but the highest tested dose reduces its concentration in plasma to the control level. Notably, the concentrations of ivermectin recorded in plasma of treated rats, indicate that even high doses do not reach the in vitro IC50 value of ivermectin for SARS-CoV-2 reported in the literature. On the other hand, the concentrations of ivermectin in the brain approach the values that can manifest extremely toxic effects described in humans. Veliki odmerki ivermektina povzročajo toksične učinke pri podganah po kratkotrajnem peroralnem dajanju Izvleček: Protiglivični makrociklični laktoni (ML) so najpomembnejše učinkovine v sodobni farmakoterapiji parazitskih okužb. Vendar so med pandemijo covida-19 pri ljudeh proti okužbi z virusom SARS-CoV-2 uporabljali bistveno višje odmerke ivermektina od odobrenih antiparazitičnih odmerkov. Takšna uporaba je bila ustvarjena izključno na podlagi testov in vitro, vendar ni bila uradno odobrena v nobeni državi na svetu. Zato smo izvedli študijo na podganah, ki smo jih 5 dni peroralno zdravili z 0,6, 1,2, 2,4 in 4,8 mg ivermektina na kg telesne teže. Naša preiskava je pokazala, da ivermektin v povišanih odmerkih, ki se uporabljajo pri ljudeh proti virusu SARS-CoV-2 (3-, 6-, 12- in 24-krat večjih od antiparazitskega odmerka 0,2 mg/kg), povzroča spremembe v številu eritrocitov in zvišuje raven jetrnih encimov brez vidnih kliničnih simptomov. Histopatološke spremembe smo zabeležili v jetrih, ledvicah in testisih podgan, največji testirani odmerek pa je povzročil krvavitev v možganskem tkivu. Znano je, da ivermektin kot substrat nekoliko poveča koncentracijo encima P-450 izoforma 3A4, vendar največji testirani odmerek zmanjša njegovo koncentracijo v plazmi na kontrolno raven. Koncentracije ivermektina, zabeležene v plazmi zdravljenih podgan, kažejo, da tudi visoki odmerki ne dosežejo in vitro vrednosti IC50 ivermektina za SARS-CoV2, ki je navedena v literaturi. Po drugi strani pa se koncentracije ivermektina v možganih približujejo vrednostim, ki lahko povzročijo izjemno toksične učinke, opisane pri ljudeh. Ključne besede: ivermektin; toksičnost; SARS-CoV-2; citokrom P-450; P-gp; histopatološke spremembe; podgane

The mitochondrial electron transport chain (ETC) of Plasmodium malaria parasites is a major antimalarial drug target, but critical cytochrome (cyt) functions remain unstudied and enigmatic. Parasites express two distinct cyt c homologs (c and c-2) with unusually sparse sequence identity and uncertain fitness contributions. P. falciparum cyt c-2 is the most divergent eukaryotic cyt c homolog currently known and has sequence features predicted to be incompatible with canonical ETC function. We tagged both cyt c homologs and the related cyt c1 for inducible knockdown. Translational repression of cyt c and cyt c1 was lethal to parasites, which died from ETC dysfunction and impaired ubiquinone recycling. In contrast, cyt c-2 knockdown or knockout had little impact on blood-stage growth, indicating that parasites rely fully on the more conserved cyt c for ETC function. Biochemical and structural studies revealed that both cyt c and c-2 are hemylated by holocytochrome c synthase, but UV-vis absorbance and EPR spectra strongly suggest that cyt c-2 has an unusually open active site in which heme is stably coordinated by only a single axial amino acid ligand and can bind exogenous small molecules. These studies provide a direct dissection of cytochrome functions in the ETC of malaria parasites and identify a highly divergent Plasmodium cytochrome c with molecular adaptations that defy a conserved role in eukaryotic evolution.

Objective: Blood pressure shows a physiological diurnal rhythm. Altered blood pressure circadian rhythm is more common in the elderly. Nocturnal hypertension (NH) and/or impaired nocturnal dipping profile are associated with increased mortality risk. The CYP2J2*7 polymorphism is associated with decreased arachidonic acid metabolite levels and increased cardiovascular mortality risk in different populations. The aim of this study was to investigate whether NH was associated with the CYP2J2*7 polymorphism in an elderly Turkish population. Methods: Ambulatory blood pressure data were obtained from 120 elderly (78 women and 42 men, aged 60-105 years) volunteers during 24 h. The CYP2J2*7 (G/T) polymorphism was evaluated using a Taqman® Drug Metabolism Genotyping Assay kit and a TAQMAN ABI7900 device. Results: The CYP2J2*7 T-allele frequency was 6.7% in our study population. The 24 h, day, and night systolic blood pressures were found to be 2-5 mmHg higher in CYP2J2*7T-carriers (n=15) than in individuals with the GG genotype (n=105), however, the differences between the genotype groups were not statistically significant. The systolic blood pressure morning increase slope values of the CYP2J2*7 carriers and GG genotype group were 8.6±2.0 (mean ± standard error of mean) and 5.7±0.5, respectively, i.e., 50.7% higher in T-carriers (p=0.039). There was no statistically significant difference in the frequency of NH with the CYP2J2*7 polymorphism. Conclusion: Considering the existing literature with our findings, the CYP2J2*7 carrier status may indicate an increased risk of cardiovascular events. However, further studies are required to verify the significance of this finding.

Introduction: Campylobacter spp. are a public health concern, yet there is still no effective vaccine or medicine available. Methods: Here, we developed a Campylobacter jejuni-specific antibody and found that it targeted a menaquinol cytochrome c reductase complex QcrC. Results: The antibody was specifically reactive to multiple C. jejuni strains including clinical isolates from patients with acute enteritis and was found to inhibit the energy metabolism and growth of C. jejuni. Different culture conditions produced different expression levels of QcrC in C. jejuni, and these levels were closely related not only to the energy metabolism of C. jejuni but also its pathogenicity. Furthermore, immunization of mice with recombinant QcrC induced protective immunity against C. jejuni infection. Discussion: Taken together, our present findings highlight a possible antibody- or vaccination-based strategy to prevent or control Campylobacter infection by targeting the QcrC-mediated metabolic pathway. [ABSTRACT FROM AUTHOR]

Purple sulfur bacteria (PSB) are capable of anoxygenic photosynthesis via oxidizing reduced sulfur compounds and are considered key drivers of the sulfur cycle in a range of anoxic environments. In this study, we show that Allochromatium vinosum (a PSB species) is capable of autotrophic growth using pyrite as the electron and sulfur source. Comparative growth profile, substrate characterization, and transcriptomic sequencing data provided valuable insight into the molecular mechanisms underlying the bacterial utilization of pyrite and autotrophic growth. Specifically, the pyrite-supported cell cultures ("py"') demonstrated robust but much slower growth rates and distinct patterns from their sodium sulfide-amended positive controls. Up to ~200-fold upregulation of genes encoding various c- and b-type cytochromes was observed in "py," pointing to the high relevance of these molecules in scavenging and relaying electrons from pyrite to cytoplasmic metabolisms. Conversely, extensive downregulation of genes related to LH and RC complex components indicates that the electron source may have direct control over the bacterial cells' photosynthetic activity. In terms of sulfur metabolism, genes encoding periplasmic or membrane-bound proteins (e.g., FccAB and SoxYZ) were largely upregulated, whereas those encoding cytoplasmic proteins (e.g., Dsr and Apr groups) are extensively suppressed. Other notable differentially expressed genes are related to flagella/fimbriae/pilin(+), metal efflux(+), ferrienterochelin(-), and [NiFe] hydrogenases(+). Characterization of the biologically reacted pyrite indicates the presence of polymeric sulfur. These results have, for the first time, put the interplay of PSB and transition metal sulfide chemistry under the spotlight, with the potential to advance multiple fields, including metal and sulfur biogeochemistry, bacterial extracellular electron transfer, and artificial photosynthesis. [ABSTRACT FROM AUTHOR]

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Microorganisms are key players in the global biogeochemical sulfur cycle. Among them, some have garnered particular attention due to their electrical activity and ability to perform extracellular electron transfer. A growing body of research has highlighted their extensive phylogenetic and metabolic diversity, revealing their crucial roles in ecological processes. In this review, we delve into the electron transfer process between sulfate-reducing bacteria and anaerobic alkane-oxidizing archaea, which facilitates growth within syntrophic communities. Furthermore, we review the phenomenon of long-distance electron transfer and potential extracellular electron transfer in multicellular filamentous sulfur-oxidizing bacteria. These bacteria, with their vast application prospects and ecological significance, play a pivotal role in various ecological processes. Subsequently, we discuss the important role of the pili/cytochrome for electron transfer and presented cutting-edge approaches for exploring and studying electroactive microorganisms. This review provides a comprehensive overview of electroactive microorganisms participating in the biogeochemical sulfur cycle. By examining their electron transfer mechanisms, and the potential ecological and applied implications, we offer novel insights into microbial sulfur metabolism, thereby advancing applications in the development of sustainable bioelectronics materials and bioremediation technologies. [ABSTRACT FROM AUTHOR]

AimOur objective was to systematically assess the prevalence and clinical features of adverse events related to interactions between cannabinoids and psychotropic drugs through a retrospective chart review.Methodology1586 adverse event reports were assessed. Cases included in the analysis showed a high probability of a causal relationships between cannabinoid-psychotropic drug interactions and adverse events. Data extracted included age, sex, psychotropic drug, cannabinoid products, other medications, and the clinical outcomes and mechanisms of these interactions.ResultsCannabinoids were involved in 8% of adverse events associated with the concomitant use of psychotropic drugs and other preparations. We identified 20 reports in which side effects presented a causal relationship with the use of psychotropic drugs and cannabinoids. Preparations containing 18% or more tetrahydrocannabinol (THC), presented significant side effects with the following antidepressants: mianserine (restless legs syndrome, urogenital pain, ventricular tachycardia), mirtazapine (pancreatitis, hyperhidrosis, arthralgia), quetiapine (myocarditis, renal failure, bradycardia, sialorrhea), haloperidol (ventricular arrhythmia, prolonged QTc), aripiprazole (prolonged QTc), ventricular tachycardia) and cariprazine (stomach pain, hepatotoxicity), sertraline (ataxia, hyperactivity, coma, hallucinations, anxiety, agitation, tachycardia, panic attacks, disorientation, headache, dizziness, blurry vision, severe emesis, xerostomia, dry eyes), trazodone (disorientation, memory impairment, sedation), fluvoxamine (tachycardia, tachypnoea, dysarthria, auditory hallucinations). Two out of 20 reports (10%) analyzed in our study was related with the simultaneous use of cannabidiol (CBD) oil and sertraline. Concomitant use of those substances was associated with the adverse events in form of diarrhea, emesis, fever and severe fatigue.ConclusionClinicians need to closely monitor adverse events resulting from the combined use of cannabinoids and psychotropic medications. The accumulation of side effects and pharmacokinetic interactions (including CYP and p-glycoprotein inhibition) between these drugs can lead to clinically significant adverse outcomes.

The biological signaling molecule nitric oxide (NO) has recently emerged as a metabolic precursor for the creation of microbial natural products with diversified structures and biological activities. Within the biosynthetic gene clusters (BGCs) of these compounds, genes associated with NO production pathways have been pinpointed. In this study, we employ a nitric oxide synthase (NOS)-guided genome mining strategy for the targeted discovery of NO-derived bacterial natural products and NO-utilizing biocatalysts. We show that a conserved NOS-containing BGC, distributed across several actinobacterial genomes, is responsible for the biosynthesis of lajollamycin, a unique nitro-tetraene-containing antibiotic whose biosynthetic mechanism remains elusive. Through a combination of in vivo and in vitro studies, we unveil the first cytochrome P450 enzyme capable of catalyzing olefin nitration in natural product biosynthesis. These results not only expand the current knowledge about biosynthetic nitration processes but also offer an efficient way for targeted identification of NO-utilizing metabolic pathways and novel nitrating biocatalysts.

The fur color of mammals is mainly determined by melanin synthesized by melanocytes. Cell staining includes melanocyte development, melanin synthesis and metabolism, and signal pathways regulating melanin synthesis. Melanocytes can be classified into many types, and these types can be identified by a variety of melanocyte markers. Fur color can judge the physical condition and nutritional status of animals, and different fur colors may have certain influence on animal production. This paper reviews the structural basis and development cycle of mammalian fur color formation, describes the cytochrome process from neural crest to mature melanocytes residing in several tissues, summarizes the types of melanocytes and the markers of each type of melanocytes, and discusses the application of animal coat color in animal production, providing help for analyzing the genetic mechanism of mammalian fur color formation and providing effective suggestions for animal production affected by fur color. [ABSTRACT FROM AUTHOR]

Cellobiose dehydrogenase (CDH) is applied as a bioelectrocatalyst in biosensors because its mobile cytochrome domain is capable of direct electron transfer. This study investigates the electron transfer mechanism of CDH molecules embedded in the polycation polyethyleneimine (PEI), which has been reported as a current‐boosting component of CDH‐based biosensors. By immobilizing different concentrations of CDH and its isolated cytochrome domain in PEI films, we found that increasing concentrations of cytochrome enhanced the film conductivity (up to 251±8 mS cm−1) through improved electron transfer between the protein redox centers. The increased electrical conductivity of the film contacts CDH molecules at a greater distance from the electrode. The cross‐linker poly(ethylene glycol) diglycidyl ether improves the packing and contacting of the cytochrome domains, whereas glutaraldehyde reduces the current obtained. Deglycosylation of CDH enhances the conductivity of enzyme‐polymer films by up to 34 %, implying a higher number of productive electron‐hopping events between cytochrome domains due to enhanced mobility or reduced shielding. By balancing negative charges on the CDH surface at neutral and alkaline pH, PEI increases the interdomain electron transfer and the electrical film conductivity. The resulting increased current output is relevant for in vivo bioanalytical applications. [ABSTRACT FROM AUTHOR]

Geobacter sulfurreducens profoundly shapes Earth's biogeochemistry by discharging respiratory electrons to minerals and other microbes through filaments of a two-decades-long debated identity. Cryogenic electron microscopy has revealed filaments of redox-active cytochromes, but the same filaments have exhibited hallmarks of organic metal-like conductivity under cytochrome denaturing/inhibiting conditions. Prior structure-based calculations and kinetic analyses on multi-heme proteins are synthesized herein to propose that a minimum of ~7 cytochrome 'nanowires' can carry the respiratory flux of a Geobacter cell, which is known to express somewhat more (=20) filaments to increase the likelihood of productive contacts. By contrast, prior electrical and spectroscopic structural characterizations are argued to be physiologically irrelevant or physically implausible for the known cytochrome filaments because of experimental artifacts and sample impurities. This perspective clarifies our mechanistic understanding of physiological metalmicrobe interactions and advances synthetic biology efforts to optimize those interactions for bioremediation and energy or chemical production. [ABSTRACT FROM AUTHOR]

Cyprinidae species are the most abundant and widely distributed fish species in the inland waters of Iraq. Cyprinids are complex species,and it is difficult to identify them on the basis of morphology. Thus, the morphological characteristics must be achieved and confirmed by molecular analysis. Twenty specimens of Cyprinion kaisHeckel, 1843 (Piscies, Cypriniformes, Cyprinidae) were collected from two localities at Tigris Riverinthe middle of Iraq:five specimens from Al-Tharthar Lake, Saladin Province,and 15 specimens from Al-Zubaydiyah sub-district, Wasit Province. The DNA sequences of C.kais were done using the mitochondrial DNA cytochrome b (cytb) gene. After analysis, the sequences were compared with sequences of other fish genera and species available in GenBank. The barcoding result (DNA sequencing) showed that it fit with C. kais. We conclude the results of the current study confirm that the validity of the morphological diagnosis of C.kais, using DNA sequencing analysis.

Denitrification plays a central role in the global nitrogen cycle, reducing and removing nitrogen from marine and terrestrial ecosystems. The flux of nitrogen species through this pathway has a widespread impact, affecting ecological carrying capacity, agriculture, and climate. Nitrite reductase (Nir) and nitric oxide reductase (NOR) are the two central enzymes in this pathway. Here we present a previously unreported Nir domain architecture in members of phylum Chloroflexi. Phylogenetic analyses of protein domains within Nir indicate that an ancestral horizontal transfer and fusion event produced this chimeric domain architecture. We also identify an expanded genomic diversity of a rarely reported NOR subtype, eNOR. Together, these results suggest a greater diversity of denitrification enzyme arrangements exist than have been previously reported.

Geobacter sulfurreducens profoundly shapes Earth’s biogeochemistry by discharging respiratory electrons to minerals and other microbes through filaments of a two-decades-long debated identity. Cryogenic electron microscopy has revealed filaments of redox-active cytochromes, but the same filaments have exhibited hallmarks of organic metal-like conductivity under cytochrome denaturing/inhibiting conditions. Prior structure-based calculations and kinetic analyses on multi-heme proteins are synthesized herein to propose that a minimum of ~7 cytochrome ‘nanowires’ can carry the respiratory flux of a Geobacter cell, which is known to express somewhat more (≥20) filaments to increase the likelihood of productive contacts. By contrast, prior electrical and spectroscopic structural characterizations are argued to be physiologically irrelevant or physically implausible for the known cytochrome filaments because of experimental artifacts and sample impurities. This perspective clarifies our mechanistic understanding of physiological metal-microbe interactions and advances synthetic biology efforts to optimize those interactions for bioremediation and energy or chemical production.

Abstract Cellobiose dehydrogenase (CDH) is applied as a bioelectrocatalyst in biosensors because its mobile cytochrome domain is capable of direct electron transfer. This study investigates the electron transfer mechanism of CDH molecules embedded in the polycation polyethyleneimine (PEI), which has been reported as a current‐boosting component of CDH‐based biosensors. By immobilizing different concentrations of CDH and its isolated cytochrome domain in PEI films, we found that increasing concentrations of cytochrome enhanced the film conductivity (up to 251±8 mS cm−1) through improved electron transfer between the protein redox centers. The increased electrical conductivity of the film contacts CDH molecules at a greater distance from the electrode. The cross‐linker poly(ethylene glycol) diglycidyl ether improves the packing and contacting of the cytochrome domains, whereas glutaraldehyde reduces the current obtained. Deglycosylation of CDH enhances the conductivity of enzyme‐polymer films by up to 34 %, implying a higher number of productive electron‐hopping events between cytochrome domains due to enhanced mobility or reduced shielding. By balancing negative charges on the CDH surface at neutral and alkaline pH, PEI increases the interdomain electron transfer and the electrical film conductivity. The resulting increased current output is relevant for in vivo bioanalytical applications.

The terminal oxidases of bacterial aerobic respiratory chains are redox-active electrogenic enzymes that catalyze the four-electron reduction of O2 to 2H2O taking out electrons from quinol or cytochrome c. Living bacteria often deal with carbon monoxide (CO) which can act as both a signaling molecule and a poison. Bacterial terminal oxidases contain hemes; therefore, they are potential targets for CO. However, our knowledge of this issue is limited and contradictory. Here, we investigated the effect of CO on the cell growth and aerobic respiration of three different Escherichia coli mutants, each expressing only one terminal quinol oxidase: cytochrome bd-I, cytochrome bd-II, or cytochrome bo3. We found that following the addition of CO to bd-I-only cells, a minimal effect on growth was observed, whereas the growth of both bd-II-only and bo3-only strains was severely impaired. Consistently, the degree of resistance of aerobic respiration of bd-I-only cells to CO is high, as opposed to high CO sensitivity displayed by bd-II-only and bo3-only cells consuming O2. Such a difference between the oxidases in sensitivity to CO was also observed with isolated membranes of the mutants. Accordingly, O2 consumption of wild-type cells showed relatively low CO sensitivity under conditions favoring the expression of a bd-type oxidase. [ABSTRACT FROM AUTHOR]

Saponin-rich medicinal plants, particularly ginseng and Pseudo ginseng, are valuable in traditional medical practice due to the presence of different saponins. These plants benefit from natural saponins/triterpenoids drugs, such as Ginsenosides, Gypenosides, Platycodins, and Lancemasides. Ginsenosides are highly required for research and functional materials preparation in industrial practices, and some compounds, like Compound-K, have been taken to human trials for various therapeutic applications. To elucidate the genes/transcripts profiles responsible for secondary metabolites and ginsenoside biosynthesis in Ginseng and Pseudo ginseng plant genomes, a comparative analysis was conducted in this study. Nine plant genomes with a 99% BUSCO completeness score were used, resulting in 49 KEGG secondary metabolite pathways, 571 cytochromes genes with 42 families, and 3529 carbohydrate genes with 103 superfamilies. The comparative analysis revealed 24 genes/transcripts belonging to the CYP716 family, which is involved in the ginsenoside biosynthesis pathway. Additionally, it found that various ginsenosides demonstrated strong binding affinity with twelve targets, with ginsenoside Rg3, Rg2, Rh1, Rh5, F3, Rh9, Panaxadione, Protopanaxatriol, Floral ginsenoside C, and Floral ginsenoside E exhibiting the highest binding affinities with the tested enzymes. Since these groups of enzymes are not yet fully characterized for Pseudo ginseng plants in the interconversion of triterpenoids, this comparative bioinformatics analysis could aid experimentalists in selecting and conducting characterization with practical knowledge. [ABSTRACT FROM AUTHOR]

The modalities for prescribing a psychotropic (dose and choice of molecule) are currently unsatisfactory, which can lead to a lack of efficacy of the treatment associated with prolonged exposure of the patient to the symptoms of his or her illness and the side effects of the molecule. In order to improve the quality of treatment prescription, a part of the current biomedical research is dedicated to the development of pharmacogenetic tools for individualized prescription. In this guideline, we will present the genes of interest with level 1 clinical recommendations according to PharmGKB for the two major families of psychotropics: antipsychotics and antidepressants. For antipsychotics, there are CYP2D6 and CYP3A4, and for antidepressants, CYP2B6, CYP2D6, and CYP2C19. The study will focus on describing the role of each gene, presenting the variants that cause functional changes, and discussing the implications for prescriptions in clinical practice. [ABSTRACT FROM AUTHOR]

Background: Vitamins have a great impact on metabolis. Aims: To determine the role of 1,25(OH)2D On Cytochromes CYP27A1 and CYP27B1 in Periodontitis. Material and Method: The investigation was carried out on 45 participants of ages within the range of (30-45 years) who were attending the private dental clinics. Diagnosis of chronic periodontitis was established depending on dental history, clinical examinations (periodontal indices). All participants were examined by the same dentist. They were classified into three groups: Group 1 (control negative): (15) participants with normal serum vitamin D3 level and with pocket depth =3 mm, good oral health and normal periodontal tissues and no previous history of periodontal diseases. Group 2 (control positive): (15) participants with normal serum vitamin D3 level and periodontitis with pocket depth =5 mm, they received placebo medication orally, Group3(treatment): (15) participants with vitamin D3 deficiency (below 30 IU), and periodontitis with pocket depth ≥5 mm, they received oral Vitamin D3 fast acting liquid soft gel capsule 2000 IU/day for 3 months. 3 blood samples were taken from each participant at 0,45,90 days, for research examinations. CYP27A1, CYP27B1 serum levels was measured for each sample in three groups by ELISA kit. Result: there was a highly significant reduction in CYP27A1 serum level in the treatment group at the ninety days of the study while there was no significant elevation CYP27B1 serum level in all groups during 45,90 days of the study. Conclusion: The present study suggested that the 1,25(OH)2D has effects on serum levels of both Cytochromes CYP27A1 and CYP27B1 and this was associated with periodontitis. [ABSTRACT FROM AUTHOR]

The recent reclassification of the strict anaerobe Geobacter sulfurreducens bacterium as aerotolerant brought attention for oxidative stress protection pathways. Although the electron transfer pathways for oxygen detoxification are not well established, evidence was obtained for the formation of a redox complex between the periplasmic triheme cytochrome PpcA and the diheme cytochrome peroxidase MacA. In the latter, the reduction of the high-potential heme triggers a conformational change that displaces the axial histidine of the low-potential heme with peroxidase activity. More recently, a possible involvement of the triheme periplasmic cytochrome family (PpcA-E) in the protection from oxidative stress in G. sulfurreducens was suggested. To evaluate this hypothesis, we investigated the electron transfer reaction and the biomolecular interaction between each PpcA-E cytochrome and MacA. Using a newly developed method that relies on the different NMR spectral signatures of the heme proteins, we directly monitored the electron transfer reaction from reduced PpcA-E cytochromes to oxidized MacA. The results obtained showed a complete electron transfer from the cytochromes to the high-potential heme of MacA. This highlights PpcA-E cytochromes' efficient role in providing the necessary reducing power to mitigate oxidative stress situations, hence contributing to a better knowledge of oxidative stress protection pathways in G. sulfurreducens. [ABSTRACT FROM AUTHOR]

Aim: We aimed to systematically evaluate the prevalence and clinical characteristics of adverse events associated with the adaptogens and antidepressant drug interactions in a retrospective chart review. Methodology: A total of 1,816 reports of adverse events were evaluated. Cases were included in the analysis if the pharmacoepidemiological analysis showed the presence of a high probability of a causal relationship between an adaptogen and antidepressant interaction and the occurrence of adverse events. The following data were extracted from the reports: age, sex, antidepressant, plant products containing adaptogens, other concomitant medications, and clinical consequences of the interactions and their possible mechanisms. Results: Adaptogens were involved in 9% of adverse events associated with the concomitant use of antidepressants and other preparations. We identified 30 reports in which side effects presented a causal relationship with the use of antidepressants and adaptogens. Here, we present the list of adaptogens with the corresponding antidepressants and the side effects caused by their interactions: Withania somnifera: reboxetine (testicle pain and ejaculatory dysfunctions), sertraline (severe diarrhea), escitalopram (myalgia, epigastric pain, nausea, vomiting, restless legs syndrome, and severe cough), and paroxetine (generalized myalgia, ophthalmalgia, and ocular hypertension); Eleutherococcus senticosus: duloxetine (upper gastrointestinal bleeding), paroxetine (epistaxis), sertraline (vaginal hemorrhage), and agomelatine (irritability, agitation, headache, and dizziness); Schisandra chinensis: bupropion (arthralgia and thrombocytopenia), amitriptyline (delirium), and fluoxetine (dysuria); Tribulus terrestris: citalopram (generalized pruritus), escitalopram (galactorrhea), and trazodone (psoriasis relapse); Coptis chinensis: mianserin (arrhythmias), mirtazapine (edema of lower limbs and myalgia), and fluoxetine (gynecomastia); Cimicifuga racemosa: mianserin (restless legs syndrome), paroxetine (gynecomastia and mastalgia), and venlafaxine (myocardial infarction); Gynostemma pentaphyllum: duloxetine (back pain); Cordyceps sinensis: sertraline (upper gastrointestinal bleeding); Lepidium meyenii: mianserin (restless legs syndrome); and Scutellaria baicalensis: bupropion (seizures). Conclusion: Clinicians should monitor the adverse events associated with the concomitant use of adaptogens and antidepressant drugs in patients with mental disorders. Aggregation of side effects and pharmacokinetic interactions (inhibition of CYP and p-glycoprotein) between those medicines may result in clinically significant adverse events. [ABSTRACT FROM AUTHOR]

Extracellular electron transfer (EET) is the physiological process that enables the reduction or oxidation of molecules and minerals beyond the surface of a microbial cell. The first bacteria characterized with this capability were Shewanella and Geobacter, both reported to couple their growth to the reduction of iron or manganese oxide minerals located extracellularly. A key difference between EET and nearly every other respiratory activity on Earth is the need to transfer electrons beyond the cell membrane. The past decade has resolved how well-conserved strategies conduct electrons from the inner membrane to the outer surface. However, recent data suggest a much wider and less well understood collection of mechanisms enabling electron transfer to distant acceptors. This review reflects the current state of knowledge from Shewanella and Geobacter, specifically focusing on transfer across the outer membrane and beyond—an activity that enables reduction of highly variable minerals, electrodes, and even other organisms. [ABSTRACT FROM AUTHOR]

Cytochrome P450 enzyme metabolism is altered by environmental and genetic factors, which can affect the efficacy and safety of opioids. This article describes CYP polymorphisms and how pharmacogenetic testing could be used to help clinicians make safer decisions about opioid use in patients. [ABSTRACT FROM AUTHOR]

Distances between Fe ions in multiheme cytochromes are sufficiently short to make the intramolecular dipole-dipole interaction between hemes probable. In the analysis of EPR data from cytochromes, this interaction has thus far been ignored under the assumption that spectra are the simple sum of non-interacting components. Here, we use a recently developed low-frequency broadband EPR spectrometer to establish the extent of dipolar interaction in the example cytochromes, characterize its spectral signatures, and identify present limitations in the analysis. Broadband EPR spectra of Shewanella oneidensis MR-1 small tetraheme cytochrome (STC) have been collected over the frequency range of 0.45 to 13.11 GHz, and they have been compared to similar data from Desulfovibrio vulgaris Hildenborough cytochrome c3. The two cases are representative examples of two very different heme topologies and corresponding electron-transfer properties in tetraheme proteins. While in cytochrome c3, the six Fe-Fe distances can be sorted into two well-separated groups, those in STC are diffuse. Since the onset of dipolar interaction between Fe-Fe pairs is already observed in the X-band, the g values are determined in the simulation of the 13.11 GHz spectrum. Low-frequency spectra are analyzed with the inclusion of dipolar interaction based on available structural data on mutual distances and orientations between all hemes. In this procedure, all 24 possible assignments of individual heme spectra to heme topologies are sampled. The 24 configurations can be reduced to a few, but inspection falls short of a unique assignment, due to a remaining lack of understanding of the fine details of these complex spectra. In general, the EPR analysis suggests the four-heme system in c3 to be more rigid than that in STC, which is proposed to be related to different physiological roles in electron transfer. [ABSTRACT FROM AUTHOR]

Cellobiose dehydrogenase (CDH) is a bioelectrocatalyst that enables direct electron transfer (DET) in biosensors and biofuel cells. The application of this bidomain hemoflavoenzyme for physiological glucose measurements is limited by its acidic pH optimum and slow interdomain electron transfer (IET) at pH 7.5. The reason for this rate‐limiting electron transfer step is electrostatic repulsion at the interface between the catalytic dehydrogenase domain and the electron mediating cytochrome domain (CYT). We applied rational interface engineering to accelerate the IET for the pH prevailing in blood or interstitial fluid. Phylogenetic and structural analyses guided the design of 17 variants in which acidic amino acids were mutated at the CYT domain. Five mutations (G71K, D160K, Q174K, D177K, M180K) increased the pH optimum and IET rate. Structure‐based analysis of the variants suggested two mechanisms explaining the improvements: electrostatic steering and stabilization of the closed state by hydrogen bonding. Combining the mutations into six combinatorial variants with up to five mutations shifted the pH optimum from 4.5 to 7.0 and increased the IET at pH 7.5 over 12‐fold from 0.1 to 1.24 s−1. While the mutants sustained a high enzymatic activity and even surpassed the IET of the wild‐type enzyme, the accumulated positive charges on the CYT domain decreased DET, highlighting the importance of CYT for IET and DET. This study shows that interface engineering is an effective strategy to shift the pH optimum and improve the IET of CDH, but future work needs to maintain the DET of the CYT domain for bioelectronic applications. PDB Code(s): 4QI6; [ABSTRACT FROM AUTHOR]

The recent reclassification of the strict anaerobe Geobacter sulfurreducens bacterium as aerotolerant brought attention for oxidative stress protection pathways. Although the electron transfer pathways for oxygen detoxification are not well established, evidence was obtained for the formation of a redox complex between the periplasmic triheme cytochrome PpcA and the diheme cytochrome peroxidase MacA. In the latter, the reduction of the high-potential heme triggers a conformational change that displaces the axial histidine of the low-potential heme with peroxidase activity. More recently, a possible involvement of the triheme periplasmic cytochrome family (PpcA-E) in the protection from oxidative stress in G. sulfurreducens was suggested. To evaluate this hypothesis, we investigated the electron transfer reaction and the biomolecular interaction between each PpcA-E cytochrome and MacA. Using a newly developed method that relies on the different NMR spectral signatures of the heme proteins, we directly monitored the electron transfer reaction from reduced PpcA-E cytochromes to oxidized MacA. The results obtained showed a complete electron transfer from the cytochromes to the high-potential heme of MacA. This highlights PpcA-E cytochromes’ efficient role in providing the necessary reducing power to mitigate oxidative stress situations, hence contributing to a better knowledge of oxidative stress protection pathways in G. sulfurreducens.

Midostaurin is often prescribed with azole antifungals in patients with leukaemia, either for aspergillosis prophylaxis or treatment. Midostaurin is extensively metabolized by cytochrome (CYP) 3A4. In addition, it inhibits and induces various CYPs at therapeutic concentrations. Thus, midostaurin is associated with a high potential for drug‐drug interactions (DDIs), both as a substrate (victim) and as a perpetrator. However, data on midostaurin as a perpetrator of DDIs are scarce, as most pharmacokinetic studies have focused on midostaurin as a victim drug. We report a clinically relevant bidirectional DDI between midostaurin and voriconazole during induction treatment. A 49‐year‐old woman with acute myeloid leukaemia developed invasive pulmonary aspergillosis after induction chemotherapy. She was treated with voriconazole at standard dosage. Six days after starting midostaurin, she developed visual hallucinations with a concurrent sharp increase in voriconazole blood concentration (Ctrough 10.3 mg L−1, target Ctrough 1‐5 mg L−1). Neurotoxicity was considered to be related to voriconazole overexposure. The concentration of midostaurin was concomitantly six‐fold above the average expected level, but without safety issues. Midostaurin was stopped and the dosage of voriconazole was adjusted with therapeutic drug monitoring. The evolution was favourable, with quick resolution and no recurrence of visual hallucinations. To our knowledge, this is the first case suggesting that midostaurin and voriconazole reciprocally inhibit each other's metabolism, leading to increased exposure of both. This case highlights the knowledge gap regarding drug‐drug interactions between midostaurin and azole antifungals. Close clinical and therapeutic drug monitoring is advised in such cases. [ABSTRACT FROM AUTHOR]

Objective: We aimed to unravel potential pharmacokinetic interactions between aripiprazole and duloxetine. Methods: Plasma concentrations of aripiprazole in two groups of 78 patients each, receiving aripiprazole as a monotherapy or combined with duloxetine, were compared. A potential impact of duloxetine on the metabolism of aripiprazole was expected in higher plasma concentrations of aripiprazole and higher dose‐adjusted plasma concentrations. Results: Patients co‐medicated with duloxetine showed significantly higher plasma concentrations of aripiprazole by 54.2% (p = 0.019). Dose‐adjusted plasma concentrations were 45.6% higher (p = 0.001); 12.8% of these patients exhibited aripiprazole plasma concentrations above the upper limit of the therapeutic reference range, in the control group this was only the case for 10.3% of the patients. A positive relationship was found between the daily dose of duloxetine and dose‐adjusted plasma concentrations of aripiprazole (p = 0.034). As dehydroaripiprazole concentrations were not available, conclusions for the active moiety (aripiprazole plus dehydroaripiprazole) could not be drawn. Conclusions: Combining duloxetine and aripiprazole leads to significantly higher drug concentrations of aripiprazole, most likely via an inhibition of cytochrome P450 CYP2D6 and to a lesser extent of CYP3A4 by duloxetine. Clinicians have to consider increasing aripiprazole concentrations when adding duloxetine to a treatment regimen with aripiprazole. [ABSTRACT FROM AUTHOR]

Accumulating clinical evidence indicates extensive inter-individual variations in the effectiveness and adverse effects of standard treatment protocols, which are largely attributed to the multifactorial regulation of the hepatic CYP-dependent drug metabolism that is connected with either transcriptional or post-translational modifications. Age and stress belong to the most important factors in CYP gene regulation. Alterations in neuroendocrine responses to stress, which are associated with modified hypothalamo-pituitary-adrenal axis function, usually accompany ageing. In this light, ageing followed by a decline of the functional integrity of organs, including liver, a failure in preserving homeostasis under stress, increased morbidity and susceptibility to stress, among others, holds a determinant role in the CYP-catalyzed drug metabolism and thus, in the outcome and toxicity of pharmacotherapy. Modifications in the drug metabolizing capacity of the liver with age have been reported and in particular, a decline in the activity of the main CYP isoforms in male senescent rats, indicating decreased metabolism and higher levels of the drug-substrates in their blood. These factors along with the restricted experience in the use of the most medicines in childhood and elderly, could explain at an extent the inter-individual variability in drug efficacy and toxicity outcomes, and underscore the necessity of designing the treatment protocols, accordingly. [ABSTRACT FROM AUTHOR]

The mitochondrial electron transport chain (ETC) of Plasmodium malaria parasites is a major antimalarial drug target, but critical cytochrome (cyt) functions remain unstudied and enigmatic. Parasites express two distinct cyt c homologs (c and c-2) with unusually sparse sequence identity and uncertain fitness contributions. P.falciparum cyt c-2 is the most divergent eukaryotic cyt c homolog currently known and has sequence features predicted to be incompatible with canonical ETC function. We tagged both cyt c homologs and the related cyt c1 for inducible knockdown. Translational repression of cyt c and cyt c1 was lethal to parasites, which died from ETC dysfunction and impaired ubiquinone recycling. In contrast, cyt c-2 knockdown or knockout had little impact on blood-stage growth, indicating that parasites rely fully on the more conserved cyt c for ETC function. Biochemical and structural studies revealed that both cyt c and c-2 are hemylated by holocytochrome c synthase, but UV-vis absorbance and EPR spectra strongly suggest that cyt c-2 has an unusually open active site in which heme is stably coordinated by only a single axial amino acid ligand and can bind exogenous small molecules. These studies provide a direct dissection of cytochrome functions in the ETC of malaria parasites and identify a highly divergent Plasmodium cytochrome c with molecular adaptations that defy a conserved role in eukaryotic evolution. [ABSTRACT FROM AUTHOR]

Geobacter bacteria produce conductive pili appendages and an outer membrane‐anchored lipopolysaccharide to immobilize uranium extracellularly. Yet, some radionuclide enters the cell envelope, where is rapidly mineralized by periplasmic c‐cytochromes. To investigate this reaction, we constructed cell envelope biomimetic interfaces containing PpcA, the most conserved and abundant periplasmic c‐cytochrome in Geobacter species. Cyclic voltammograms revealed much higher rate constants for uranium than for iron, the natural electron acceptor of Geobacter, independently of the metal‐ligand complexation. These results are consistent with a much higher affinity of PpcA for uranium than for iron, providing a plausible explanation for the rapid mineralization of the radionuclide inside the cell envelope. The studies highlight the value of electrochemical biomimetic interfaces to dissect the contribution of cell envelope cytochromes to metal reduction and identify redox‐active proteins with the affinity needed for sensory applications. [ABSTRACT FROM AUTHOR]

Rapamycin and its derivatives are mTOR inhibitors which are FDA-approved for use as immunosuppressants and chemotherapeutic agents. These agents are currently approved to treat renal cell carcinomas, soft tissue sarcomas, and other rare tumors. As tumor treatment paradigms are moving away from organ-based drug selection and moving towards tumor characteristics for individualized treatment it is important to identify as many properties as possible that impact the efficacy of the rapalogues. A review of the current literature was conducted to identify enzymes involved in the metabolism of Sirolimus, Everolimus, Ridaforolimus, and Temsirolimus along with characteristics of tumors that predict the efficacy of these agents. This review also sought to establish whether the genetic characteristics of the patient might influence the activity of the rapalogues or lead to side effects from these agents. Current evidence suggests that tumors with mutations in the mTOR signal transduction pathway are sensitive to rapalogue treatment; the rapalogues are metabolized by cytochromes such as CYP3A4, CYP3A5, and CYP2C8 and transported by ABC transporters that are known to vary in activity in individuals; and that tumors can express these transporters and detoxifying enzymes. This results in three levels of genetic analysis that could impact the effectiveness of the mTOR inhibitors. [ABSTRACT FROM AUTHOR]

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BackgroundMost species of Shewanella harbor two ferrochelatase paralogues for the biosynthesis of c-type cytochromes, which are crucial for their respiratory versatility. In our previous study of the Shewanella loihica PV-4 strain, we found that the disruption of hemH1 but not hemH2 resulted in a significant accumulation of extracellular protoporphyrin IX (PPIX), but it is different in Shewanella oneidensis MR-1. Hence, the function and transcriptional regulation of two ferrochelatase genes, hemH1 and hemH2, are investigated in S. oneidensis MR-1.ResultIn the present study, deletion of either hemH1 or hemH2 in S. oneidensis MR-1 did not lead to overproduction of extracellular protoporphyrin IX (PPIX) as previously described in the hemH1 mutants of S. loihica PV-4. Moreover, supplement of exogenous hemins made it possible to generate the hemH1 and hemH2 double mutant in MR-1, but not in PV-4. Under aerobic condition, exogenous hemins were required for the growth of MR-1ΔhemH1ΔhemH2, which also overproduced extracellular PPIX. These results suggest that heme is essential for aerobic growth of Shewanella species and MR-1 could also uptake hemin for biosynthesis of essential cytochrome(s) and respiration. Besides, the exogenous hemin mediated CymA cytochrome maturation and the cellular KatB catalase activity. Both hemH paralogues were transcribed in wild-type MR-1, and the hemH2 transcription was remarkably up-regulated in MR-1ΔhemH1 mutant to compensate for the loss of hemH1. The periplasmic glutathione peroxidase gene pgpD, located in the same operon with hemH2, and a large gene cluster coding for iron, heme (hemin) uptake systems are absent in the PV-4 genome.ConclusionOur results indicate that the genetic divergence in gene content and gene expression between these Shewanella species, accounting for the phenotypic difference described here, might be due to their speciation and adaptation to the specific habitats (iron-rich deep-sea vent versus iron-poor freshwater) in which they evolved and the generated mutants could potentially be utilized for commercial production of PPIX.

Accumulating clinical evidence indicates extensive inter-individual variations in the effectiveness and adverse effects of standard treatment protocols, which are largely attributed to the multifactorial regulation of the hepatic CYP-dependent drug metabolism that is connected with either transcriptional or post-translational modifications. Age and stress belong to the most important factors in CYP gene regulation. Alterations in neuroendocrine responses to stress, which are associated with modified hypothalamo-pituitary-adrenal axis function, usually accompany ageing. In this light, ageing followed by a decline of the functional integrity of organs, including liver, a failure in preserving homeostasis under stress, increased morbidity and susceptibility to stress, among others, holds a determinant role in the CYP-catalyzed drug metabolism and thus, in the outcome and toxicity of pharmacotherapy. Modifications in the drug metabolizing capacity of the liver with age have been reported and in particular, a decline in the activity of the main CYP isoforms in male senescent rats, indicating decreased metabolism and higher levels of the drug-substrates in their blood. These factors along with the restricted experience in the use of the most medicines in childhood and elderly, could explain at an extent the inter-individual variability in drug efficacy and toxicity outcomes, and underscore the necessity of designing the treatment protocols, accordingly.