Fluorescence in situ hybridization (FISH) was performed in 17 myeloid leukemia patients and seven lymphoid leukemia/ lymphoma patients who exhibited chromosomal abnormalities on the short arm of chromosome 17, in order to detect a commonly deleted region on chromosome band 17p13. Twenty-four leukemia/lymphoma patients studied cytogenetically at our institution over a period of 10 years had detectable 17p abnormalities such as translocation (six patients), addition (11 patients) and deletion of 17p13 (seven patients). A 17p abnormality was the only abnormality present in three patients. Most of the patients had additional complex cytogenetic abnormalities. The diagnosis was acute myeloid leukemia (AML) in 10 patients, two each with chronic myeloid leukemia (CML), acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL) and myelodysplastic syndrome (MDS) and the remaining three with malignant lymphoma (ML). Seven cosmid probes (D17S34, cCl17-624, cCl17-453, D17S379, cCl17-636, cCl17-732 and TP53) which mapped on 17p13 were used to analyze the allelic deletion. Eighty percent (19 out of 24) of the informative leukemia patients exhibited allelic loss in 17p13.3 at cC17-624. The smallest region of an overlapping deletion was observed on chromosome band 17p13.3 between cCl17-624 and cCl17-453. Patients with transloation involving 17p also showed deletion at cCl17-624 and cCl17-453. We hypothesize that this region contains a novel tumor suppressor gene(s) that is involved in leukemogenesis.

Patients with renal failure undergoing hemodialysis (HD) are susceptible to muscle cramps during and after HD. Muscle cramps are defined as the sudden onset of a prolonged involuntary muscle contraction accompanied by severe pain. Through HD, water-soluble vitamins are drawn out with water. Since biotin, a water-soluble vitamin, plays an essential role as one of the coenzymes in producing energy, we have hypothesized that deficiency of biotin may be responsible for HD-associated cramps. We previously reported that biotin administration ameliorated the muscle cramps, despite the elevated plasma biotin levels before HD and biotin administration, as judged by an enzyme-linked immunosorbent assay (ELISA). However, the ELISA measures not only biotin but also total avidin-binding substances (TABS) including biotin metabolites. In the present study, we determined biotin in HD patients as well as healthy controls, using a newly developed method with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The plasma samples were collected from 28 HD patients (16 patients with cramps and 12 patients without cramps) before HD and biotin administration and from 11 controls. The results showed that the accumulation of biotin and TABS in plasma of HD patients compared to controls. Importantly, the levels of biotin metabolites, i.e. TABS subtracted by biotin, increased significantly in patients with cramps over those without cramps. Moreover, the levels of biotin metabolites were significantly higher in patients with a poor response to administered biotin, compared to those with a good response. We propose that accumulated biotin metabolites impair biotin's functions as a coenzyme.

A simple, rapid, and selective method for determination of plasma biotin was developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After single-step protein precipitation with methanol, biotin and stable isotope-labeled biotin as an internal standard (IS) were chromatographed on a pentafluorophenyl stationary-phase column (2.1 × 100 mm, 2.7 μm) under isocratic conditions using 10 mm ammonium formate-acetonitrile (93:7, v/v) at a flow rate of 0.6 mL/min. The total chromatographic runtime was 5 min for each injection. Detection was performed in a positive electrospray ionization mode by monitoring selected ion transitions at m/z 245.1/227.0 and 249.1/231.0 for biotin and the IS, respectively. The calibration curve was linear in the range of 0.05-2 ng/mL using 300 μL of plasma. The intra- and inter-day precisions were all <7.1%. The accuracy varied from -0.7 to 8.2%. The developed UHPLC-MS/MS method was successfully applied to determine plasma biotin concentrations in hemodialysis patients. Copyright © 2016 John Wiley & Sons, Ltd.

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