ABSTRACT
Study has been made of the thermoluminescence (TL) response of silica-based Ge-doped cylindrical, flat and photonic crystal fibres (referred to herein as PCF-collapsed) to electron (6, 12 and 20 MeV) and photon (6, 10 MV) irradiation and 1.25 MeV γ-rays, for doses from 0.1 Gy to 100 Gy. The electron and photon irradiations were delivered through use of a Varian Model 2100C linear accelerator located at the University of Malaya Medical Centre and γ-rays delivered from a 60Co irradiator located at the Secondary Standard Dosimetry Laboratory (SSDL), Malaysian Nuclear Agency. Tailor-made to be of various dimensions and dopant concentrations (6-10% Ge), the fibres were observed to provide TL yield linear with radiation dose, reproducibility being within 1-5%, with insensitivity to energy and angular variation. The sensitivity dependency of both detectors with respect to field size follows the dependency of the output factors. For flat fibres exposed to 6 MV X-rays, the 6% Ge-doped fibre provided the greatest TL yield while PCF-collapsed showed a response 2.4 times greater than that of the 6% Ge-doped flat fibres. The response of cylindrical fibres increased with core size. The fibres offer uniform response, high spatial resolution and sensitivity, providing the basis of promising TL systems for radiotherapy applications.
Subject(s)
Silicon Dioxide/radiation effects , Thermoluminescent Dosimetry , Dose-Response Relationship, Radiation , Electrons , Gamma Rays , Optical Fibers , Photons , Radiotherapy/methods , Silicon Dioxide/chemistrySubject(s)
Meningeal Neoplasms/diagnosis , Meningeal Neoplasms/etiology , Multiple Myeloma/complications , Multiple Myeloma/diagnosis , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Combined Modality Therapy , Fatal Outcome , Female , Hematopoietic Stem Cell Transplantation , Humans , Leukemia, Plasma Cell/diagnosis , Leukemia, Plasma Cell/drug therapy , Magnetic Resonance Imaging , Meningeal Neoplasms/therapy , Middle Aged , Multiple Myeloma/therapy , Neoplasms, Second Primary/diagnosis , Neoplasms, Second Primary/drug therapy , Transplantation, AutologousABSTRACT
BACKGROUND: Hypomethylating drugs are useful in the management of myelodysplastic syndrome (MDS). Two of these drugs, azacitidine and decitabine, have received FDA approval for the treatment of MDS and chronic myelomonocytic leukemia (CMML). However, phase 2 and 3 studies that assessed these agents in MDS included only a small number of patients with CMML. The objective of this study was to evaluate the efficacy and safety of azacitidine in the treatment of CMML. METHODS: The records of thirty-eight patients diagnosed with CMML and treated with azacitidine at our institution were reviewed. Azacitidine was administered at 75 mg/m(2) /day for 7 days or 100 mg/m(2) /day for 5 days every 4 weeks. Patients who received at least 1 cycle of the drug were considered evaluable for response. RESULTS: Response was assessed by the modified International Working Group (IWG) criteria. The overall response rate was 39% (14 of 36); complete response (CR) rate was 11% (4 of 36); partial response (PR) rate was 3% (1 of 36); hematologic improvement (HI) was 25% (9 of 36). The median overall survival was 12 months. There was a statistically significant overall survival advantage in responders compared with nonresponders: 15.5 months versus 9 months, respectively (P = .04). Treatment was generally well tolerated. One of 2 patients had complete resolution of a skin rash that was due to monocytic infiltration. CONCLUSIONS: Azacitidine is active in the treatment of CMML. The therapy-associated toxicity is acceptable. Our results support further investigation of azacitidine in CMML, particularly in combination with other agents.
Subject(s)
Antimetabolites, Antineoplastic/therapeutic use , Azacitidine/therapeutic use , Leukemia, Myelomonocytic, Chronic/drug therapy , Adult , Aged , Aged, 80 and over , Azacitidine/adverse effects , Azacitidine/analogs & derivatives , Decitabine , Female , Humans , Leukemia, Myelomonocytic, Chronic/mortality , Male , Middle Aged , Retrospective StudiesABSTRACT
We compared sex chromosomal and autosomal regions of similar GC contents and found that the human Y chromosome contains nine times as many full-length (FL) ancestral LINE-1 (L1) elements per megabase as do autosomes and that the X chromosome contains three times as many. In addition, both sex chromosomes contain a ca. twofold excess of elements that are >500 bp but not long enough to be capable of autonomous replication. In contrast, the autosomes are not deficient in short (<500 bp) L1 elements or SINE elements relative to the sex chromosomes. Since neither the Y nor the X chromosome, when present in males, can be cleared of deleterious genetic loci by recombination, we conclude that most FL L1s were deleterious and thus subject to purifying selection. Comparison between nonrecombining and recombining regions of autosome 21 supported this conclusion. We were able to identify a subset of loci in the human DNA database that once contained active L1 elements, and we found by using the polymerase chain reaction that 72% of them no longer contain L1 elements in a representative of each of eight different ethnic groups. Genetic damage produced by both L1 retrotransposition and ectopic (nonallelic) recombination between L1 elements could provide the basis for their negative selection.
