Measurement of serum hepcidin-25 levels as a potential test for diagnosing hemochromatosis and related disorders

石川県立中央病院金沢大学医薬保健研究域医学系Iron overload syndromes include a wide spectrum of genetic and acquired conditions. Recent studies suggest suppressed hepcidin synthesis in the liver to be the molecular basis of hemochromatosis. However, a liver with acquired iron overload synthesizes an adequate amount of hepcidin. Thus, hepcidin could function as a biochemical marker for differential diagnosis of iron overload syndromes. Methods We measured serum iron parameters and hepcidin- 25 levels followed by sequencing HFE, HJV, HAMP, TFR2, and SLC40A1 genes in 13 Japanese patients with iron overload syndromes. In addition, we performed direct measurement of serum hepcidin-25 levels using liquid chromatography-tandem mass spectrometry in 3 Japanese patients with aceruloplasminemia and 4 Italians with HFE hemochromatosis. Results One patient with HJV hemochromatosis, 2 with TFR2 hemochromatosis, and 3 with ferroportin disease were found among the 13 Japanese patients. The remaining 7 Japanese patients showed no evidence for genetic basis of iron overload syndrome. As far as the serum hepcidin-25 was concerned, seven patients with hemochromatosis and 3 with aceruloplasminemia showed markedly decreased serum hepcidin-25 levels. In contrast, 3 patients with ferroportin disease and 7 with secondary iron overload syndromes showed serum hepcidin levels parallel to their hyperferritinemia. Patients with iron overload syndromes were divided into 2 phenotypes presenting as low and high hepcidinemia. These were then associated with their genotypes. Conclusion Determining serum hepcidin-25 levels may aid differential diagnosis of iron overload syndromes prior to genetic analysis. © Springer 2010

PARP-1 and Ku compete for repair of DNA double strand breaks by distinct NHEJ pathways

Poly(ADP-ribose)polymerase 1 (PARP-1) recognizes DNA strand interruptions in vivo and triggers its own modification as well as that of other proteins by the sequential addition of ADP-ribose to form polymers. This modification causes a release of PARP-1 from DNA ends and initiates a variety of responses including DNA repair. While PARP-1 has been firmly implicated in base excision and single strand break repair, its role in the repair of DNA double strand breaks (DSBs) remains unclear. Here, we show that PARP-1, probably together with DNA ligase III, operates in an alternative pathway of non-homologous end joining (NHEJ) that functions as backup to the classical pathway of NHEJ that utilizes DNA-PKcs, Ku, DNA ligase IV, XRCC4, XLF/Cernunnos and Artemis. PARP-1 binds to DNA ends in direct competition with Ku. However, in irradiated cells the higher affinity of Ku for DSBs and an excessive number of other forms of competing DNA lesions limit its contribution to DSB repair. When essential components of the classical pathway of NHEJ are absent, PARP-1 is recruited for DSB repair, particularly in the absence of Ku and non-DSB lesions. This form of DSB repair is sensitive to PARP-1 inhibitors. The results define the function of PARP-1 in DSB repair and characterize a candidate pathway responsible for joining errors causing genomic instability and cancer

Current trends in drug metabolism and pharmacokinetics.

Pharmacokinetics (PK) is the study of the absorption, distribution, metabolism, and excretion (ADME) processes of a drug. Understanding PK properties is essential for drug development and precision medication. In this review we provided an overview of recent research on PK with focus on the following aspects: (1) an update on drug-metabolizing enzymes and transporters in the determination of PK, as well as advances in xenobiotic receptors and noncoding RNAs (ncRNAs) in the modulation of PK, providing new understanding of the transcriptional and posttranscriptional regulatory mechanisms that result in inter-individual variations in pharmacotherapy; (2) current status and trends in assessing drug-drug interactions, especially interactions between drugs and herbs, between drugs and therapeutic biologics, and microbiota-mediated interactions; (3) advances in understanding the effects of diseases on PK, particularly changes in metabolizing enzymes and transporters with disease progression; (4) trends in mathematical modeling including physiologically-based PK modeling and novel animal models such as CRISPR/Cas9-based animal models for DMPK studies; (5) emerging non-classical xenobiotic metabolic pathways and the involvement of novel metabolic enzymes, especially non-P450s. Existing challenges and perspectives on future directions are discussed, and may stimulate the development of new research models, technologies, and strategies towards the development of better drugs and improved clinical practice

Physical Dosimetry at Nagasaki-Europium-152 of Stone Embankment and Electron Spin Resonance of Teeth from Atomic Bomb Survivors : I. DOSIMETRY

Gamma-rays from thermal neutron-induced radionuclide of ^Eu in rocks near the ground center of the atomic bomb (A-bomb) explosion (hypocenter) in Nagasaki were measured with a pure germanium semiconductor detector. Depth profiles of ^Eu activity were obtained for 22 core samples taken from stone embankments on both sides of two rivers (the River Shirnono-kawa and the River Urakami-gawa) within 500 m of the hypocenter since the activity in the rocks has a history of incident neutron energy. Although the activities of the surface sections were varied from sample to sample, the slopes of depth profile in rock and the value of ^Eu activity in the depth of 240-280 mm were similar among the samples taken from the same location. On the other hand, neutron penetrating experiments using both a fast and a thermal neutron reactor were performed to obtain the relationship between the incident neutron energy spectra and the depth profiles of ^Eu activity in rock. The depth profiles in the bomb exposed samples were close to that obtained by using a 10 mm polyethelene moderator in the reactor experiments. Electron spin resonance (ESR) measurements from teeth of A-bomb survivors were carried out to estimate the individual gamma-ray dose of the survivors. The absorbed dose of ten tooth samples was estimated by ESR dosimetry. The results of ESR dosimetry were consistent with the calculations of tissue dose in air of A-bombs and irradiated shielding configuration of individuals