Search

Purpose: We evaluated the magnetic resonance imaging (MRI) features of ovarian teratomas with somatic-type malignancy (TSMs) and benign ovarian mature cystic teratomas (MCTs) to determine the diagnostic contribution of the MRI findings for differentiating these two teratomas., Methods: We compared the MRI findings between ovarian TSMs (n = 10) and MCTs (n = 193), and we conducted a receiver operating characteristic (ROC) analysis to determine the MRI findings' contribution to the differentiation of TSMs from MCTs., Results: The maximum diameters of whole lesion and the largest solid component in the TSMs were larger than those of the MCTs (p = 0.0001 and p < 0.0001, respectively). Fat tissue in solid components was seen in 73/116 (62.9%) MCTs but in none of the TSMs (p = 0.0001). Ring-like enhancement in solid components was seen in 60/116 (51.7%) MCTs and none of the TSMs (p = 0.0031). On dynamic contrast-enhanced MRI (DCE MRI), all of the solid components in the TSMs showed a high- or intermediate-risk time intensity curve (TIC), and those in 113 of the 116 (97.4%) MCTs showed a low-risk TIC (p < 0.0001). The area under the curve of the ROC analysis using the high-/intermediate-risk TIC on DCE MRI was the highest (0.99) for differentiating TSMs from MCTs: sensitivity 100%, specificity 97.4%, positive predictive value 75.0%, negative predictive value 100%, and accuracy, 97.6%., Conclusion: Compared to ovarian MCTs, ovarian TSMs are larger and have larger solid components with high- or intermediate-risk TICs on DCE MRI. Ovarian MCTs frequently show small solid components with fat tissue, ring-like enhancement, and a low-risk TIC on DCE MRI., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The interposition of a cleavable linkage by enzymes on the renal brush border membrane constitutes a promising approach for reducing the renal radioactivity levels of radiolabeled low-molecular-weight antibody fragments and constructs (LMW Abs). Herein, we applied the molecular design to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-based reagents for radiotheranostic applications with trivalent radiometals. DOTA or a derivative thereof was conjugated to a Fab through an FGK linkage ([ 111 In]In-DO3A i Bu-Bn-FGK-Fab or [ 111 In]In-DOTA-Bn-FGK-Fab). When injected into mice, both generated radiometabolites, [ 111 In]In-DO3A i Bu-Bn-F and [ 111 In]In-DOTA-Bn-F, by the angiotensin-converting enzyme at similar rates. Both exhibited significantly lower renal radioactivity levels than a 111 In-labeled Fab prepared by the conventional procedure ([ 111 In]In-DOTA-Bn-SCN-Fab). The different elimination rates of each radiometabolite from the kidney significantly affected the renal radioactivity levels. [ 111 In]In-DO3A i Bu-Bn-FGK-Fab preferentially reduced the renal localization without impairing tumor accumulation. These findings would pave the way for developing a DOTA-based radiotheranostic platform for LMW Abs bearing cleavable linkers for renal brush border enzymes.

1,4,7,10-Tetraazacyclododecane-1,4,7-triacetic acid (DO3A) has been used to prepare 68 Ga-labeled probes for the diagnostic counterpart of radiotheranostic applications. While DO3A provides stable complexes with therapeutic radionuclides such as 90 Y, 177 Lu, and 225 Ac, further improvement of the in vivo stability of the Ga-DO3A complex is required. Considering the high stability of an intact Ga-DOTA complex, the stability of Ga complexes of DOTA and DO3A derivatives, including benzyl-DOTA (Bn-DOTA), was evaluated to gain fundamental knowledge for developing the next-generation radiotheranostic probes using 68 Ga as a diagnostic counterpart. Following the complexation reaction to prepare 67 Ga-labeled DOTA and DO3A derivatives, the stability of the resulting 67 Ga-labeled compounds was evaluated in murine plasma and apo-transferrin challenge. [ 67 Ga]Ga-Bn-DOTA produced two isomers, and one of the isomers exhibited the highest stability among the tested complexes. The X-ray crystallography showed that the less stable isomer of Ga-Bn-DOTA suggested an N 3 O 3 coordination geometry, while Ga-DOTA and Ga-Bn-DO3A show N 4 O 2 coordination. To further evaluate the stability, a synthetic somatostatin analogue, [Tyr 3 ]octreotide (TOC), was used as a model peptide, and p -COOH-Bn-DOTA and DO3A were conjugated with TOC to prepare DOTA-Bn-TOC and DOTATOC. [ 67 Ga]Ga-DOTA-Bn-TOC also yielded two isomers with varying stability, and one isomer exhibited significantly higher stability than [ 67 Ga]Ga-DOTATOC both in vitro and in vivo . These findings indicate that para -substituted Bn-DOTA would constitute a suitable chelating agent for developing next-generation radiotheranostic probes, although high-performance liquid chromatography purification is needed. Thus, further chemical modification on the Bn-DOTA molecule is also needed to avoid the formation of a Ga complex with the N 3 O 3 configuration., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Introduction: Radiolabeled peptides and low-molecular-weight (LMW) polypeptides show high and persistent radioactivity levels in the kidney. To develop a DOTA-based bifunctional chelating agent that provides a radiometabolite with a rapid elimination rate from the kidney, a para-carboxyl Bn-DOTA (p-COOH-Bn-DOTA) was designed, synthesized, and evaluated., Methods: A precursor compound, p-COOH-Bn-DOTA( t Bu) 4 , was synthesized in 9 steps using N-Boc-p-iodo-L-phenylalanine as the starting material. A synthetic somatostatin analog (TOC) was used as a representative peptide metabolized in the renal lysosomes. p-COOH-Bn-DOTA-conjugated TOC (DOTA-Bn-TOC) was synthesized by the conventional solid-phase peptide synthesis using p-COOH-Bn-DOTA( t Bu) 4 . DOTA-tris( t Bu ester) was also conjugated with TOC to prepare DOTATOC. 111 In-labeling of the peptides was conducted under similar conditions. The radiochemical conversions, stability against apo-transferrin (apoTf), and in vivo behaviors were compared., Results: [ 111 In]In-DOTA-Bn-TOC was obtained with higher radiochemical conversions than [ 111 In]In-DOTATOC. Both 111 In-labeled TOC derivatives remained stable against apoTf. In biodistribution studies, [ 111 In]In-DOTA-Bn-TOC exhibited higher initial uptake in the kidney, followed by a faster elimination rate of radioactivity into the urine than [ 111 In]In-DOTATOC. The metabolic studies showed that the shorter residence time of the radiometabolite from [ 111 In]In-DOTA-Bn-TOC was responsible for the renal radioactivity decline., Conclusion: p-COOH-Bn-DOTA provides stable 111 In-labeled peptides in high yields at low peptide concentrations. p-COOH-Bn-DOTA also provides a radiometabolite with a short residence time in the kidney. Such characteristics would render p-COOH-Bn-DOTA useful to the future application to radiolabeled LMW polypeptides with low renal radioactivity levels., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Cancer immunotherapy involves the use of the immune system for cancer treatment. Recently, immune checkpoint-blocking antibodies have become integral for the treatment of some cancers. However, small molecules exhibit advantages over monoclonal antibody drugs, such as cell penetration, long half-life, and low manufacturing costs, and the possibility of oral administration. Thus, it is imperative to develop small-molecule immune checkpoint inhibitors. Previously, we have screened a library of synthetic indole-alkaloid-type compounds, which are produced by diversity-enhanced extracts of Japanese cornelian cherry, and reported that an unnatural pentacyclic compound inhibits CTLA-4 gene expression. In this study, immune checkpoint inhibitors with increased potency were developed by introducing substituents and conversion of functional groups based on the unnatural pentacyclic compound. The developed compounds suppressed not only CTLA-4 and PD-L1 gene expression but also protein expression on the cell surface. Their efficacy was not as potent as that of the existing small-molecule immune checkpoint inhibitors, but, to the best of our knowledge, the developed compounds are the first reported dual small-molecule inhibitors of CTLA-4 and PD-L1., Competing Interests: SK, SM, JZ, and OY were employed by the company FUSO Pharmaceutical Industries, Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Suzuki, Ichinohe, Sugawara, Kida, Murase, Zhang, Yamada, Hattori, Oshima and Kikuchi.)

Molecular mechanisms of radiation dose-rate effects are not well understood. Among many possibilities, long-lasting sustained alterations in protein levels would provide critical information. To evaluate sustained effects after acute and chronic radiation exposure, we analyzed alterations in protein expression in the livers of mice. Acute exposure consisted of a lethal dose of 8 Gy and a sublethal dose of 4 Gy, with analysis conducted 6 days and 3 months after irradiation, respectively. Chronic irradiation consisted of a total dose of 8 Gy delivered over 400 days (20 mGy/day). Analyses following chronic irradiation were done immediately and at 3 months after the end of the exposure. Based on antibody arrays of protein expression following both acute lethal and sublethal dose exposures, common alterations in the expression of two proteins were detected. In the sublethal dose exposure, the expression of additional proteins was altered 3 months after irradiation. Immunohistochemical analysis showed that the increase in one of the two commonly altered proteins, MyD88, was observed around blood vessels in the liver. The alterations in protein expression after chronic radiation exposure were different from those caused by acute radiation exposures. Alterations in the expression of proteins related to inflammation and apoptosis, such as caspase 12, were observed even at 3 months after the end of the chronic radiation exposure. The alterations in protein expression depended on the dose, the dose rate, and the passage of time after irradiation. These changes could be involved in long-term effects of radiation in the liver., (© The Author 2017. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.)

A library of iridoid-conjugated indole alkaloid-like compounds was constructed from diversity-enhanced extracts, which constitutes an approach for increasing the chemical diversity of natural-product-like compounds by combining natural product chemistry and diversity-oriented synthesis. Pharmacological screening of the library revealed a seed compound that can be used for the development of small molecular immune checkpoint inhibitors.

The value of cervical spine or shoulder radiography has been established for the detection of Pancoast tumors. However, for the detection of lung cancers other than Pancoast tumors, the value of these skeletal radiographies has not been assessed. The aim of our study was to determine how many patients first presented to orthopedists with manifestations of lung cancer on skeletal radiographs and to present several cases for illustration. From the registry of the pathology department of our hospital, we identified 345 lung cancer patients diagnosed histologically over 10 years. From these patients, we selected 310 who had no previous history of malignancies at histological diagnosis of lung cancer. The study population consisted of individuals from the selected patients who had presented once or more to orthopedists at our hospital for any reason, at up to 2 years prior to histological diagnosis of lung cancer. For the study population, all radiological examinations performed by the orthopedists were reviewed by radiologists. The study population included 46 patients constituting 14.8 % (46/310) of the selected patients. Of these 46 patients, 37 (80.4 %) received 97 skeletal radiographies. Reviewing these skeletal radiographies disclosed lung tumors on 13 in 11 (11/46, 23.9 %) of the patients. We found that more than 10 % of lung cancer patients with no previous history of malignancies had presented to orthopedists on one or more occasions, at up to 2 years before histological diagnosis, and that approximately 25 % of these patients had manifestations of lung cancer on skeletal radiographs.

Primary retroperitoneal transitional cell carcinomas (TCCs) are extremely rare neoplasms for which prognosis is very poor. We present a case that underwent complete remission after radiotherapy and concurrent oral chemotherapy. A 68-year-old woman presented with acute onset of bloody stool. Urgent colonoscopy only detected haemorrhoids. Subsequent abdominal ultrasonography revealed a mass of 7 cm in maximal diameter in the left iliac fossa. Laparotomy disclosed a retroperitoneal mass that could not be dissected and therefore only incision biopsy was performed. After a final diagnosis of primary retroperitoneal TCC, chemotherapy with tegafur-uracil (UFT) was initiated but was not effective. Subsequently, radiotherapy was initiated concurrently with UFT at a total dose of 50 Gy in 25 fractions. At 20 months after radiotherapy, the tumour seemed to have completely remitted. At the last follow-up, ten years from radiotherapy, computed tomography revealed no recurrence. We identified only three single case reports regarding primary retroperitoneal TCC over the last five decades. All patients died from the tumour 8-24 months after diagnosis or treatment. Based on the success of our case, radiotherapy with concurrent oral chemotherapy should be considered as an option for unresected cases.

Radiation exposure induces acute myeloid leukemia (AML) in humans and mice. Recent studies postulated that AML stem cells of spontaneous human AML arise from hematopoietic stem cells. However, other studies support the possibility that short-lived committed progenitors transform into AML stem cells, accompanied by a particular gene mutation. It remains unclear whether AML stem cells are present in radiation-induced AML, and information regarding AML-initiating cells is lacking. In this study, we identified and analyzed AML stem cells of mice with radiation-induced AML. The AML stem cells were identified by transplanting 100 bone marrow cells from mice with radiation-induced AML. We injected 100 cells of each of seven cell populations corresponding to different stages of hematopoietic cell differentiation and compared the latencies of AMLs induced in recipient mice. The identified radiation-induced AML stem cells frequently displayed similarities in both CD antigen and gene expression profiles with normal common myeloid progenitors. The number of common myeloid progenitor-like AML stem cells was significantly increased in mice with radiation-induced AML, but the progeny of common myeloid progenitors was decreased. In addition, analysis of radiation effects on the hematopoietic system showed that common myeloid progenitor cells were extremely radiosensitive and that their numbers remained at low levels for more than 2 months after radiation exposure. Our results suggest that murine radiation-induced AML stem cells arise from radiosensitive cells at a common myeloid progenitor stage.

Purpose: To understand the mechanisms of life-shortening due to early neoplastic death caused by chronic low dose-rate (LDR; 20 mGy/22 h/day) radiation which accumulates to a high dose (HD; 8 Gy) (LDR/HD) as reported previously., Materials and Methods: Female B6C3F(1) mice were continuously exposed to LDR/HD gamma-rays under specific-pathogen-free (SPF) conditions for 400 days. OV3121 cells, which were derived from an ovarian granulosa cell tumour that arose in irradiated B6C3F(1) mice, were inoculated into LDR/HD irradiated and age-matched non-irradiated control mice. The transplantability of tumour cells as well as T cell subsets and the proliferative activities of T cells were compared between irradiated and non-irradiated mice., Results: We found that tumour formation of subcutaneously inoculated tumour cells occurred earlier in irradiated mice than in non-irradiated mice. Proliferative activity of draining lymph node lymphocytes against transplanted tumour cells as well as allogeneic mixed lymphocyte reactions were significantly reduced in irradiated mice compared to non-irradiated mice., Conclusions: These results suggest that decreased tumour-specific immune response due to LDR/HD irradiation may enhance tumorigenesis resulting in life-shortening of mice after chronic LDR/HD irradiation.

The ataxia telangiectasia mutated (ATM)-p53 pathway is a well-known main signal transduction pathway for cellular responses, which is activated by γ-ray irradiation. Microarray analysis showed changes in the expressions of IFN-stimulated genes (ISG) in γ-ray-irradiated Balb/cA/Atm-deficient mouse embryonic fibroblasts (MEF) (ATM-KO), indicating that another pathway for cellular responses besides the ATM-p53 pathway was activated by γ-ray irradiation. The basal expression levels of Irf7 and Stat1 in ATM-KO and p53-deficient MEFs (p53-KO) were higher than those in Atm-wild-type MEFs (ATM-WT) and p53-wild-type MEFs (p53-WT), respectively. Irradiation stimulated the expressions of Irf7 and Stat1 in ATM-KO, p53-KO, ATM-WT, and p53-WT, indicating that upregulation of Irf7 and Stat1 expressions by irradiation did not depend on the ATM-p53 pathway. When conditioned medium (CM) obtained from irradiated ATM-WT or ATM-KO was added to nonirradiated MEFs, the expressions of Irf7 and Stat1 increased. We predicted that gene activation in nonirradiated MEFs was caused by IFN-α/β. Unexpectedly, significant amount of IFN-α/β could not be detected in the CM from irradiated ATM-WT or ATM-KO. Meanwhile, increased expression of Ccl5 (RANTES) protein was detected in the CM from irradiated MEFs. These results indicate that ISGs were activated by γ-ray irradiation independently of the ATM-p53 pathway and gene activation was caused by radiation-induced soluble factors., (©2011 AACR.)

The time course of the changes in the expression of p53-mediated genes in vivo after high doses of chronic low-dose-rate γ radiation remains unclear. Here we analyzed peripheral blood cell counts and the expression of p53-mediated genes in the spleens of mice chronically irradiated at low dose rate (0.0167 Gy/h) for 1-40 days. Low-dose-rate irradiation induced p53-dependent chronic decreases in white blood cell (WBC) counts in p53 wild-type mice. Upregulation of p53-mediated genes by low-dose-rate radiation was confirmed in the whole spleen cells from the p53 wild-type mice, while suppressed gene expression was observed in the spleen cells of p53-deficient mice. The expression of p21 and Bax in radiosensitive cells such as T and B lymphocytes from low-dose-rate irradiated mice at 10, 20, and 40 days were increased, although that of Mdm2 in both the lymphocytes was decreased at 20 and 40 days. Moreover, spleen weights for low-dose-rate irradiated mice were decreased at 20 and 40 days. Thus downregulation of Mdm2 in both T and B lymphocytes by low-dose-rate radiation may cause higher p53 activation; further, higher p53 expression may determine the radiosensitivity and cause a reduction in the spleen weights in low-dose-rate irradiated mice. These results indicate that p53 may be chronically activated by low-dose-rate radiation.

In vivo modulation of gene expression profiles after low-dose and low-dose-rate irradiation has been observed in a variety of experimental systems. However, few studies actually investigated the underlying mechanisms for these genetic responses. In this study, we used pre-existing microarray data and searched for gene modulations in response to long-term, low-dose-rate irradiation. Nucleotide sequences in the neighboring region of the up-regulated, down-regulated, and unaffected genes were retrieved from the Entrez Gene database, and recognition sequences for transcription factors (TFs) were searched using the TFSEARCH database. As a result, we suggested 21 potential TF-binding sites with significantly different incidence between the three gene groups (up-regulated, down-regulated and unaffected gene groups). The binding sites for sterol regulatory element-binding protein 1 (SREBP-1), aryl hydrocarbon receptor (AhR/Ar) and olfactory 1 (Olf-1) were suggested to be involved in up-regulation, while the binding sites for glucocorticoid receptor (GR(GGTACAANNT GTYCTK) ) and hepatocyte nuclear factor 1 (HNF-1) were suggested to be involved in down-regulation of the genes. In addition, the binding sites for activating enhancer-binding protein 4 (AP-4), nuclear factor-κB (NFκB), GR (NNNNNNCNNTNTGTNCTNN) and early growth response 3 (Egr-3) were correlated with modulation of gene expression regardless of the direction of modulation. Our results suggest that these TF-binding sites are involved in gene modulations after long-term continuous irradiation with low-dose-rate γ rays. GR and/or SREBP-1 might be associated with the altered metabolic process observed in liver after exposure to low-dose-rate irradiation.

Changes in gene expression profiles in mouse liver induced by long-term low-dose-rate γ irradiation were examined by microarray analysis. Three groups of male C57BL/6J mice were exposed to whole-body radiation at dose rates of 17-20 mGy/day, 0.86-1.0 mGy/day or 0.042-0.050 mGy/day for 401-485 days with cumulative doses of approximately 8 Gy, 0.4 Gy or 0.02 Gy, respectively. The gene expression levels in the livers of six animals from each exposure group were compared individually with that of pooled sham-irradiated animals. Some genes revealed a large variation in expression levels among individuals within each group, and the number of genes showing common changes in individuals from each group was limited: 20 and 11 genes showed more than 1.5-fold modulation with 17-20 mGy/day and 0.86-1.0 mGy/day, respectively. Three genes showed more than 1.5-fold modulation even at the lowest dose-rate of 0.04-0.05 mGy/day. Most of these genes were down-regulated. RT-PCR analysis confirmed the expression profiles of the majority of these genes. The results indicate that a few genes are modulated in response to very low-dose-rate irradiation. The functional analysis suggests that these genes may influence many processes, including obesity and tumorigenesis.

Soft tissue sarcomas are rare biologically and histologically heterogeneous neoplasms that may arise throughout the body. The preferred treatment is total resection with a sufficient margin. Radiotherapy with or without chemotherapy offers another treatment option, but its effectiveness is limited. Hyperthermia, a treatment method that heats tumour tissue by exposing the target tissues to conductive heat sources or non-ionising radiation, is known to enhance the effect of radiotherapy. We report a case of an elderly man with a second recurrent myxofibrosarcoma in the left groin, who responded well to radiotherapy in combination with hyperthermia. This combination treatment was effective in maintaining the patient's quality of life during his remaining years.

Contributing factors for the antimicrobial activity enhancement of N-terminally engineered mutants of cell-penetrating apidaecins were analyzed based on their cell-penetration efficiency. The flow cytometric analysis of the engineered apidaecins labeled with carboxyfluorescein (FAM) revealed their enhanced cell-penetrating efficiencies into Escherichia coli that should be one of key factors causing the enhanced antimicrobial activity. It is noteworthy that, for one mutant, the enhancement in antimicrobial activity (18-fold higher than wild type) was greater than that of cell penetration (5.9-fold), suggesting that the N-terminal mutation may reinforce both interaction with unidentified intracellular target(s) and cell-penetration efficiency., (2010 Elsevier Inc. All rights reserved.)

The effect of dose rate on radiation-induced mutations in two somatic tissues, the spleen and liver, was examined in transgenic gpt delta mice. These mice can be used for the detection of deletion-type mutations, and these are the major type of mutation induced by radiation. The dose rates examined were 920 mGy/min, 1 mGy/min and 12.5 microGy/min. In both tissues, the number of mutations increased with increasing dose at each of the three dose rates examined. The mutation induction rate was dependent on the dose rate. The mutation induction rate was higher in the spleen than in the liver at the medium dose rate but was similar in the two tissues at the high and low dose rates. The mutation induction rate in the liver did not show much change between the medium and low dose rates. Analysis of the molecular nature of the mutations indicated that 2- to 1,000-bp deletion mutations were specifically induced by radiation in both tissues after high- and low-dose-rate irradiation. The occurrence of deletion mutation without any sequence homology at the break point was elevated in spleen after high-dose-rate irradiation. The results indicate that the mutagenic effects of radiation in somatic tissues are dependent on dose rate and that there is some variability between tissues.

The chemically modified thanatins with the methyl group (CH(3)), ethyl group (C(2)H(5)), and normal-octyl group (C(8)H(17)) at the side-chain of cysteine residues were synthesized. The octyl group modified form exhibited 8-fold higher antimicrobial activity against Micrococcus luteus than wild type thanatin. It was found that there was an equilateral correlation between antimicrobial activity and side-chain hydrophobicity at the cysteine residues in thanatin.

Measuring global gene expression using cDNA or oligonucleotide microarrays is an effective approach to understanding the complex mechanisms of the effects of radiation. However, few studies have been carried out that investigate gene expression in vivo after prolonged exposure to low-dose-rate radiation. In this study, C57BL/6J mice were continuously irradiated with gamma-rays for 485 days at dose-rates of 0.032-13 microGy/min. Gene expression profiles in the kidney and testis from irradiated and unirradiated mice were analyzed, and differentially expressed genes were identified. A combination of pathway analysis and hierarchical clustering of differentially expressed genes revealed that expression of genes involved in mitochondrial oxidative phosphorylation was elevated in the kidney after irradiation at the dose-rates of 0.65 microGy/min and 13 microGy/min. Expression of cell cycle-associated genes was not profoundly modulated in the kidney, in contrast to the response to acute irradiation, suggesting a threshold in the dose-rate for modulation of the expression of cell cycle-related genes in vivo following exposure to radiation. We demonstrated that changes to the gene expression profile in the testis were largely different from those in the kidney. The Gene Ontology categories "DNA metabolism", "response to DNA damage" and "DNA replication" overlapped significantly with the clusters of genes whose expression decreased with an increase in the dose-rate to the testis. These observations provide a fundamental insight into the organ-specific responses to low-dose-rate radiation.

Chronological changes in the chromosome aberration rates of splenocytes from specific-pathogen-free (SPF) mice after continuous and long-term exposure to low-dose-rate gamma rays were studied. Incidences of dicentrics plus centric rings (Dic+Rc), detected by conventional Giemsa staining, and dicentric chromosomes, detected by fluorescence in situ hybridization (Dic by FISH) using a centromere probe, showed an essentially linear increase up to a total accumulated dose of 8000 mGy after irradiation for about 400 days at a low dose rate of 20 mGy/day. For comparison, acute high-dose-rate and medium-dose-rate irradiation were performed. The values of the alpha coefficients in the linear regression lines for these unstable-type aberrations decreased as the dose rates were lowered from medium dose rates (200 and 400 mGy/day) to low dose rates (1 and 20 mGy/day). The dose and dose-rate effectiveness factor (DDREF), estimated by the ratio of calculated incidences using the best-fit regression lines at a high dose rate (890 mGy/min) and low dose rate (20 mGy/day), was 4.5 for Dic by FISH and 5.2 for Dic+Rc, respectively, at the same dose of 100 mGy, while different DDREFs were obtained for different accumulated doses. This is the first study to provide information regarding the effects of long-term exposure to low-dose-rate radiation on chromosomes.

Seven mutant forms of the antibacterial peptide apidaecin with increased activity were created by combinatorial mutagenesis targeted to the three N-terminal amino acid residues that had previously been identified as a nonessential region. An in vitro MIC assay revealed that the amino acid substitutions in the functionally variable region were effective in improving differential activity toward the four gram-negative bacteria tested, while a gram-positive bacterium was unaffected.

Chronological changes of chromosome aberration rates related to accumulated doses in chronically exposed humans and animals at a low-dose-rate have not been well studied. C3H female specific pathogen-free mice (8 weeks of age) were chronically irradiated. Chromosome aberration rate in mouse splenocytes after long-term exposure to low-dose-rate (LDR) gamma-rays was serially determined by conventional Giemsa method. Incidence of dicentrics and centric rings increased almost linearly up to 8000 mGy following irradiation for about 400 days at a LDR of 20 mGy/day. Clear dose-rate effects were observed in the chromosome aberration frequencies between dose rates of 20 mGy/day and 200 Gy/day. Furthermore, the frequencies of complex aberrations increased as accumulated doses increased in LDR irradiation. This trend was also observed for the incidences of micronuclei and trisomies of chromosomes 5, 13 and 18 in splenocytes, detected by micronucleus assay and metaphase fluorescence in situ hybridization (FISH) method, respectively. Incidences of 2-4 micronuclei and trisomy increased in mouse splenocytes after irradiation of 8000 mGy at a LDR of 20 mGy/day. These complex chromosome aberrations and numerical chromosome aberrations seem to be induced indirectly after radiation exposure and thus the results indicate that continuous gamma-ray irradiation for 400 days at LDR of 20 mGy/day induced chromosomal instability in mice. These results are important to evaluate the biological effects of long-term exposure to LDR radiation in humans.

The health effects of low-dose radiation exposure are of public concern. Although molecular events in the cellular response to high-dose-rate radiation exposure have been fully investigated, effects of long-term exposure to extremely low-dose-rate radiation remain unclear. Protein expression was analyzed by two-dimensional electrophoresis in livers from mice irradiated for 485 days (22 hr/day) at low-dose-rates of 0.032 microGy/min, 0.65 microGy/min and 13 microGy/min (total doses of 21 mGy, 420 mGy and 8000 mGy, respectively). One of the proteins that showed marked changes in expression was identified as rhodanese (thiosulfate sulfurtransferase). Rhodanese expression was increased after irradiation at 0.65 microGy/min and 13 microGy/min, while its expression was not changed at 0.032 microGy/min. Rhodanese is a detoxification enzyme, probably related to the regulation of antioxidative function. However, antioxidative proteins, such as superoxide dismutase (SOD)1 (also known as Cu,Zn-SOD) and SOD2 (also known as Mn-SOD), which can be induced by high-dose-rate radiation, were not induced at any low-dose-rates tested. These findings indicate that rhodanese is a novel protein induced by low-dose-rate radiation, and further analysis could provide insight into the effects of extremely low-dose-rate radiation exposure.

Objective: High-dose radiation exposure induces acute myeloid leukemia (AML) in C3H mice, most of which have a frequent hemizygous deletion around the D2Mit15 marker on chromosome 2. This region includes PU.1, a critical candidate gene for initiation of leukemogenesis. To identify novel cooperative genes with PU.1, relevant to radiation-induced leukemogenesis, we analyzed the copy number alterations of tumor-related gene loci by array CGH, and their expressions in primary and transplanted AMLs., Materials and Methods: For the induction of AMLs, C3H/He Nrs mice were exposed to 3 Gy of x-rays or gamma-rays. The genomic alterations of 35 primary AMLs and 34 transplanted AMLs obtained from the recipient mice transplanted the primary AMLs were analyzed by array CGH. According to the genomic alterations and mutations of the 235th arginine of PU.1 allele, we classified the radiogenic AMLs into three types such as Chr2(del) PU.1(del/R235-) AML, Chr2(del) PU.1(del/R235+) AML and Chr2(intact) PU.1(R235+/R235+) AML, to compare the expression levels of 8 tumor-related genes quantitatively by real-time polymerase chain reaction and cell-surface antigen expression. Results. In addition to well-known loss of PU.1 with hemizygous deletion of chromosome 2, novel genomic alterations such as partial gain of chromosome 6 were recurrently detected in AMLs. In this study, we found similarity between cell-surface antigen expressions of bone marrows and those of spleens in AML mice and significantly higher expressions of c-myc and PU.1 expression, especially in the PU.1-deficient (Chr2(del) PU.1(del/R235-)) AML and Chr2(del) PU.1(del/R235+) compared to Chr2(intact) PU.1(R235+/R235+) AMLs., Conclusion: The new finding on upregulation of c-myc and PU.1 in both and hemizygous PU.1-deficient AMLs and different genomic alterations detected by array CGH suggests that the molecular mechanism for development of radiation-induced AML should be different among three types of AML.