mARC1 Is the Main Contributor to Metabolic Reduction of -Hydroxyurea.

-Hydroxyurea has been known since the 1960s as an antiproliferative drug and is used both in oncology and for treatment of hematological disorders such as sickle cell anemia where very high daily doses are administered. It is assumed that the cellular effect of -hydroxyurea is caused by inhibition of ribonucleotide reductase, while alternative mechanisms, e.g.

Second-Coordination-Sphere Effects Reveal Electronic Structure Differences between the Mitochondrial Amidoxime Reducing Component and Sulfite Oxidase.

A combination of X-ray absorption and low-temperature electronic absorption spectroscopies has been used to probe the geometric and electronic structures of the human mitochondrial amidoxime reducing component enzyme (hmARC1) in the oxidized Mo(VI) and reduced Mo(IV) forms. Extended X-ray absorption fine structure analysis revealed that oxidized enzyme possesses a 5-coordinate [MoO(S)(PDT)] (PDT = pyranopterin dithiolene) active site with a cysteine coordinated to Mo. A 5-coordinate geometry is retained in the reduced state, with the equatorial oxo being protonated.

mARC1 in MASLD: Modulation of lipid accumulation in human hepatocytes and adipocytes.

Background: Mutations in the gene MTARC1 (mitochondrial amidoxime-reducing component 1) protect carriers from metabolic dysfunction-associated steatohepatitis (MASH) and cirrhosis. MTARC1 encodes the mARC1 enzyme, which is localized to the mitochondria and has no known MASH-relevant molecular function. Our studies aimed to expand on the published human genetic mARC1 data and to observe the molecular effects of mARC1 modulation in preclinical MASH models.

The mitochondrial amidoxime reducing component-from prodrug-activation mechanism to drug-metabolizing enzyme and onward to drug target.

The mitochondrial amidoxime-reducing component (mARC) is one of five known molybdenum enzymes in eukaryotes. mARC belongs to the MOSC domain superfamily, a large group of so far poorly studied molybdoenzymes. mARC was initially discovered as the enzyme activating N-hydroxylated prodrugs of basic amidines but has since been shown to also reduce a variety of other N-oxygenated compounds, for example, toxic nucleobase analogs.

Reduction of Hydrogen Peroxide by Human Mitochondrial Amidoxime Reducing Component Enzymes.

The mitochondrial amidoxime reducing component (mARC) is a human molybdoenzyme known to catalyze the reduction of various -oxygenated substrates. The physiological function of mARC enzymes, however, remains unknown. In this study, we examine the reduction of hydrogen peroxide (HO) by the human mARC1 and mARC2 enzymes.

New Design of an Activity Assay Suitable for High-Throughput Screening of Substrates and Inhibitors of the Mitochondrial Amidoxime Reducing Component (mARC).

The mitochondrial amidoxime-reducing component (mARC) is one of the simplest molybdenum-containing enzymes. mARC is among a few known reducing enzymes playing an important role in drug metabolism in mammals. Here, an assay based on the fluorescence of NADH is reported for the rapid detection of substrates and potential inhibitors of mARC.

The History of mARC.

The mitochondrial amidoxime-reducing component (mARC) is the most recently discovered molybdoenzyme in humans after sulfite oxidase, xanthine oxidase and aldehyde oxidase. Here, the timeline of mARC's discovery is briefly described. The story begins with investigations into -oxidation of pharmaceutical drugs and model compounds.

Active Site Structures of the -Hydroxylaminopurine Resistance Molybdoenzyme YcbX.

X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data have been used to characterize the coordination environment for the catalytic Mo site of YcbX in two different oxidation states. In the oxidized state, the Mo(VI) ion is coordinated by two terminal oxo ligands, a thiolate S atom from cysteine, and two S donors from the bidentate pyranopterin ene-1,2-dithiolate (pyranopterin dithiolene). Upon reduction, it is the more basic equatorial oxo ligand that is protonated, with a Mo-O bond distance that is best described as either a short Mo-OH bond or a long Mo-OH bond.

Accuracy of a dynamic navigation system for dental implantation with two different workflows and intraoral markers compared to static-guided implant surgery: An in-vitro study.

Purpose: To investigate the accuracy of a miniaturized dynamic navigation system with intraoral markers and two different workflows for dental implantation and to compare with static computer-assisted implant surgery (sCAIS) surgery.

Materials And Methods: Two operators performed a total of 270 implant insertions in polyurethane mandibular models under simulated clinical conditions. Implants were placed after CBCT-based virtual planning in three different groups: two workflows utilizing dynamic computer-assisted implant surgery (dCAIS; DG1: marker in CBCT; DG2: 3D-printed marker) and the others with sCAIS (TG: template guided).

Enzyme Electrode Biosensors for -Hydroxylated Prodrugs Incorporating the Mitochondrial Amidoxime Reducing Component.

Human mitochondrial amidoxime reducing component 1 and 2 (mARC1 and mARC2) were immobilised on glassy carbon electrodes using the crosslinker glutaraldehyde. Voltammetry was performed in the presence of the artificial electron transfer mediator methyl viologen, whose redox potential lies negative of the enzymes' Mo and Mo redox potentials which were determined from optical spectroelectrochemical and EPR measurements. Apparent Michaelis constants obtained from catalytic limiting currents at various substrate concentrations were comparable to those previously reported in the literature from enzymatic assays.

Letter to the editor: The clinically relevant MTARC1 p.Ala165Thr variant impacts neither the fold nor active site architecture of the human mARC1 protein.

A study recently published in Hepatology Communications provided insights into a variant of MTARC1 protein, which conveys protection against liver disease. Here, we report a crystal structure of the variant protein at near-atomic resolution and compare it to the structure of the wildtype protein.

Active site architecture reveals coordination sphere flexibility and specificity determinants in a group of closely related molybdoenzymes.

MtsZ is a molybdenum-containing methionine sulfoxide reductase that supports virulence in the human respiratory pathogen Haemophilus influenzae (Hi). HiMtsZ belongs to a group of structurally and spectroscopically uncharacterized S-/N-oxide reductases, all of which are found in bacterial pathogens. Here, we have solved the crystal structure of HiMtsZ, which reveals that the HiMtsZ substrate-binding site encompasses a previously unrecognized part that accommodates the methionine sulfoxide side chain via interaction with His182 and Arg166.

Comprehensive assessment of the photomutagenicity, photogenotoxicity and photo(cyto)toxicity of azulene.

The polycyclic aromatic hydrocarbon azulene and its naturally occurring derivative guaiazulene (1,4-dimethyl-7-isopropylazulene) are known to absorb light in the UV-vis region of the spectrum. Both compounds were reported to be mutagenic in the Salmonella typhimurium bacterial mutagenicity assay (Ames test) in strain TA102, and to cause DNA damage in the comet assay in vitro upon exposure to UVA light. In contrast, another study reported a photoprotective effect in vitro of guaiazulene.

GADD45α induction in the GreenScreen HC indicator assay does not occur independently of cytotoxicity.

Mammalian chromosomal integrity assays are influenced by cytotoxicity, a phenomenon which impacts data interpretation, assay specificity, and regulatory testing guidelines. Concordance of the GADD45α GreenScreen HC indicator assay to established in vitro and in vivo genetic toxicological assays has previously been described, yet a detailed description in the manner by which cytotoxicity influences its performance has not. Here we present a post-hoc analysis of a previously tested set of 91 proprietary and nonproprietary compounds investigating the influence of cytotoxicity on GADD45α induction and how varying assay cutoff criteria impacts assay performance.

Collaborative study on fifteen compounds in the rat-liver Comet assay integrated into 2- and 4-week repeat-dose studies.

A collaborative trial was conducted to evaluate the possibility of integrating the rat-liver Comet assay into repeat-dose toxicity studies. Fourteen laboratories from Europe, Japan and the USA tested fifteen chemicals. Two chemicals had been previously shown to induce micronuclei in an acute protocol, but were found negative in a 4-week Micronucleus (MN) Assay (benzo[a]pyrene and 1,2-dimethylhydrazine; Hamada et al.

Repair of sparfloxacin-induced photochemical DNA damage in vivo.

The induction and subsequent repair of photochemically induced DNA damage by sparfloxacin was assessed in different tissues of juvenile Wistar rats. The animals were treated once orally with 500 mg kg(-1) of sparfloxacin and irradiated 3 hours later with 7 J cm(-2) UVA. Induction and repair of DNA damage was studied in the skin, retina and cornea using the alkaline comet assay.

Detection of photogenotoxicity in skin and eye in rat with the photo comet assay.

Photosensitizing drugs increase the sensitivity of the skin and the eye toward normally harmless sunlight conditions and are known to enhance the induction of skin tumors or severe injuries to the eye. The photogenotoxicity of five common drugs (sparfloxacin, dacarbazine, chlorpromazine and 8-methoxypsoralen, promazine) was investigated in the skin as well as in the retina and cornea of Wistar rats. The compounds were administered once orally by gavage and the resulting DNA damage was analyzed in the newly developed in vivo photo comet assay.

[Radiological and clinical functional examinations 36 months after anterior cruciate ligament repair by a patellar tendon graft].

Aim: The aim of this study was to examine radiological and functional outcome measurements after anterior cruciate ligament (ACL) reconstruction with a bone-tendon-bone (BTB) graft. Investigations included assessment of bony integration conditions regarding the use of bioabsorbable cross pins or a lateral screw for femoral graft fixation. A description of radiological parameters in contrast with IKDC findings is also given.

The photo comet assay--a fast screening assay for the determination of photogenotoxicity in vitro.

Different classes of chemicals can induce a phototoxic effect by absorbing light energy within the wavelength range of sunlight. The assessment of photo-safety is therefore an obligatory part of the development of new drugs. Ten UV-vis (280-800nm)-absorbing compounds (ketoprofen, promazine, chlorpromazine, dacarbazine, acridine, lomefloxacin, 8-methoxypsoralen, chlorhexidine, titanium dioxide, octylmethoxycinnamate) were tested for their photogenotoxic potential in the alkaline comet assay in the presence and absence of UV-vis.

Role of protein synthesis in the development of a transcriptionally permissive state in one-cell stage mouse embryos.

The time of onset of gene transcription in the mouse embryo is temporally regulated. A prominent feature of this regulation is a change during the one-cell stage from a transcriptionally nonpermissive state to a transcriptionally permissive state. During the early one-cell stage, the cytoplasm is either inadequate or suppressive for nuclear gene transcription, but by the late one-cell stage, the cytoplasm acquires the ability to support gene transcription either in endogenous nuclei or exogenous nuclei introduced microsurgically.

Severe defects in the formation of epaxial musculature in open brain (opb) mutant mouse embryos.

The differentiation of somite derivatives is dependent on signals from neighboring axial structures. While ventral signals have been described extensively, little is known about dorsal influences, especially those from the dorsal half of the neural tube. Here, we describe severe phenotypic alterations in dorsal somite derivatives of homozygous open brain (opb) mutant mouse embryos which suggest crucial interactions between dorsal neural tube and dorsal somite regions.

Open brain, a new mouse mutant with severe neural tube defects, shows altered gene expression patterns in the developing spinal cord.

We describe a new mouse mutation, designated open brain (opb), which results in severe defects in the developing neural tube. Homozygous opb embryos exhibited an exencephalic malformation involving the forebrain, midbrain and hindbrain regions. The primary defect of the exencephaly could be traced back to a failure to initiate neural tube closure at the midbrain-forebrain boundary.

Effect of dronabinol on nutritional status in HIV infection.

Objective: To examine the effect of dronabinol (delta-9-tetrahydrocannabinol) on appetite and nutritional status in patients with symptomatic HIV infection and weight loss.

Design: Double-blind, randomized, placebo-controlled, crossover trial with two five-week treatment periods separated by a two-week washout period. Patients received dronabinol 5 mg twice daily before meals or placebo.

'Synaptic' bodies in the pineal glands of the cow, sheep and pig.

The present results show that 'synaptic' bodies (SB) are a heterogeneous group of organelles in the pineal glands of Artiodactyla. Basically, rod-like (ribbons) and sphere-like (spherules) SB can be distinguished. In the pig small numbers of both 'synaptic' ribbons (SR) and 'synaptic' spherules (SS) are found.