Cell cycle and LET dependence for radiation-induced mutation: a possible mechanism for reversed dose-rate effect

A previous study of the mutagenic action of 252Cf radiation in mouse L5178Y cells showed that the mutation frequency was higher when the dose was chronic rather than acute, which was in sharp contrast to the effects reported for gamma-rays (Nakamura and Sawada, 1988). A subsequent study using synchronized cells revealed that the cells at the G2/M stage were uniquely sensitive to mutation induction by 252Cf radiation but not to gamma-rays (Tauchi et al., 1993). A long phase cell population was first subjected to conditioning gamma or 252Cf radiation doses at different dose-rates. The cell cycle distribution of these cells was then observed, and they were then exposed to 252Cf radiation, and the mutation rate was determined. The G2/M fraction increased by 3- to 4-fold when the conditioning doses (2 Gy of gamma or 1 Gy of 252Cf radiation) were delivered chronically over 10 h, but only slightly when the same doses were delivered over a 1 h period or less. Subsequent 252Cf irradiation gave higher mutation frequencies in the cells pre-irradiated with gamma-rays over a protracted period of time than in those exposed with the higher dose-rate gamma-rays. These results suggest that the radiation-induced G2 block could be at least partly (but not totally) responsible for this reverse dose-rate effect (Tauchi et al. 1996). Possible factors which cause the hyper-sensitivity of G2/M cells to mutation induction by neutrons will be discussed.

Inhibitory effect of natural and environmental estrogens on thymic hormone production in thymus epithelial cell culture

The present study was carried out to assess the direct effect of natural estrogen and environmental estrogens on thymus epithelial cell (TEC) production/secretion of the thymic hormone thymosin-alpha 1 by using the technique of quantitative high-performance liquid chromatography. The presence of estrogen receptors in the TECs was also investigated. Murine TECs were cultured in the experimental DMEM medium containing various concentrations of natural or environmental estrogens, which was followed by determining the production of thymosin-alpha 1. The production of thymosin-alpha 1 by TECs was significantly inhibited by increasing concentrations of 17beta-estradiol (natural estrogen) over 3 x 10(-11) M, genistein (phytoestrogen) over 3 x 10(-9) M, coumestrol (phytoestrogen) over 3 x 10(-9) M, alpha-zearalanol (livestock anabolic) over 3 x 10(-7) and bisphenol-A (plastic) over 3 x 10(-6) M. Small amounts of estrogen receptor were present in the TECs. The above results clearly indicate that natural and environmental estrogens directly modulate TECs to produce thymic hormone probably through an estrogen receptor mechanism. Furthermore, our finding may be useful for evaluating biological effects of chemicals with estrogenic activity.

Neutron generator (HIRRAC) and dosimetry study

Dosimetry studies have been made for neutrons from a neutron generator at Hiroshima University (HIRRAC) which is designed for radiobiological research. Neutrons in an energy range from 0.07 to 2.7 MeV are available for biological irradiations. The produced neutron energies were measured and evaluated by a 3He-gas proportional counter. Energy spread was made certain to be small enough for radiobiological studies. Dose evaluations were performed by two different methods, namely use of tissue equivalent paired ionization chambers and activation of method with indium foils. Moreover, energy deposition spectra in small targets of tissue equivalent materials, so-called lineal energy spectrum, were also measured and are discussed. Specifications for biological irradiation are presented in terms of monoenergetic beam conditions, dose rates and deposited energy spectra.

Expression of full-length NBS1 protein restores normal radiation responses in cells from Nijmegen breakage syndrome patients

Cells from Nijmegen breakage syndrome (NBS) display multiple phenotypes, such as chromosomal instability, hypersensitivity to cell killing from ionizing radiation, and possibly abnormal cell cycle checkpoints. NBS1, a gene mutated in NBS patients, appears to encode a possible repair protein, which could form the foci of a sensor-like molecular complex capable of detecting DNA double strand breaks, however, it has no kinase domain for signaling DNA damage. Here, we report that the stable expression of NBS1 cDNA in NBS cells after transfection results in the complete restoration of foci formation in the nucleus, and in normal cell survival after irradiation. The prolonged G2 block observed after irradiation was also abolished by expression of NBS1, providing additional confirmation that the G2 checkpoint is abrogated in NBS cells. These results suggest that a defective NBS1 protein could be the sole cause of the NBS phenotype, and that NBS1 likely interacts with another protein(s) to produce the entire range of NBS phenotypic expression.

A polymorphic CA repeat marker at the human 27-kD calbindin (CALB1) locus

A polymorphic dinucleotide (CA) sequence was isolated from a BAC clone containing the human 27-kD calbindin (CALB1) gene at 8q21. This polymorphism will be a useful genetic marker to study genetic variations of the CALB1 gene.

Imaging features of pancreatoblastoma: a case report

We present a patient with pancreatoblastoma along with a discussion of various cross-sectional imaging features. The tumor was a large multilocular cystic mass with solid components in the left retroperitoneal space. There were fine internal echoes on ultrasonography, and the signal intensity was high on both T1- and T2-weighted MR images in most of the locules, suggesting the presence of hemorrhagic debris. Among the various retroperitoneal organs displaced by the tumor, only the pancreatic tail was inseparable from the mass, suggesting that the pancreatic tail was the origin of the tumor. Pancreatoblastoma should be included in the differential diagnosis when a large left upper quadrant mass with these imaging features is seen in infants and young children.

Aneurysmal bone cyst of the coronoid process of the mandible

A rare case of an aneurysmal bone cyst (ABC) involving the right coronoid process of the mandible in a 12-year-old girl is presented. The characteristic features with fluid-fluid levels within the lesion observed on Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) was helpful in the preoperative diagnosis.

Mutations of a novel human RAD54 homologue, RAD54B, in primary cancer

Association of breast tumor susceptibility gene products BRCA1 and BRCA2 with the RAD51 recombination protein suggested that cancer could arise through defects in recombination. The identification of NBS1, responsible for Nijmegen breakage syndrome, from the MRE11/RAD50 recombination protein complex also supports this hypothesis. However, our mutation analysis revealed that known members of the RAD52 epistasis group are rarely mutated in human primary cancer. Here we describe the isolation of a novel member of the SNF2 superfamily, characterized with sequence motifs similar to those in DNA and RNA helicases. The gene, designated RAD54B, is significantly homologous to the RAD54 recombination gene. The expression of RAD54B was high in testis and spleen, which are active in meiotic and mitotic recombination. These findings suggest that RAD54B may play an active role in recombination processes in concert with other members of the RAD52 epistasis group. RAD54B maps to human chromosome 8q21.3-q22 in a region associated with cancer-related chromosomal abnormalities. Homozygous mutations at highly conserved positions of RAD54B were observed in human primary lymphoma and colon cancer. These findings suggest that some cancers arise through alterations of the RAD54B function.

The effect of mesoporphyrin on the production of cytokines by inflammatory cells in vitro

This study was conducted to investigate a mechanism of the anti-inflammatory action of mesoporphyrin, especially the effect on the production of cytokines by some cultured inflammatory cells. Mesoporphyrin had no effect on lipopolysaccharide-induced tumor necrosis factor-alpha production by RAW 264.7 cells (murine macrophage-like cells). Mesoporphyrin inhibited interferon-gamma production by 1E10.H2 cells (murine T helper-1 cells), but not interleukin-4 production by D10.G4.1 cells (murine T helper-2 cells). Mesoporphyrin inhibited interleukin-6 production by human osteoblast-like MG-63 cells. This inhibition of interleukin-6 production is closely related to the suppression of prostaglandin E2 generation by interfering cyclooxygenase 1 and 2 enzyme activities. These data suggest that the inhibition of cytokine production is one of the anti-inflammatory mechanisms of mesoporphyrin.

Pancreatic endocrine carcinoma with multiple hormone production in a raccoon (Procyon lotor)

A pancreatic endocrine carcinoma with lung metastases was found in a 15-year-old male raccoon. This tumour was characterized by great variation in cell size and production of multiple polypeptide hormones. Endocrine markers expressed by the neoplastic cells were, in descending order of frequency, chromogranin A, pancreatic polypeptide (PP), glucagon, somatostatin and insulin. Co-expression of PP and glucagon, somatostatin or insulin was demonstrated immunohistochemically with consecutive sections, and cells with both glucagon and insulin were also observed. The pattern of co-expression was similar to that in the earliest stages of murine pancreatic development. Amyloid deposits in the islets of Langerhans, which reacted with antibody to islet amyloid polypeptide, were thought to be associated with age.

Quantitative trait loci that regulate plasma lipid concentration in hereditary obese KK and KK-Ay mice

To identify quantitative trait loci (QTLs) responsible for regulating plasma lipid concentration associated with obesity, linkage analysis was carried out on the 190 F2 progeny of a cross between C57BL/6J female and KK-Ay (Ay allele at the agouti locus congenic) male. In F2 a/a (agouti locus genotype) mice, two QTLs were identified on chromosome 1 and a QTL on chromosome 3 for total-cholesterol. A QTL for HDL-cholesterol was identified on chromosome 1 and a QTL for NEFA on chromosome 9. In F2 Ay/a mice, two QTLs for HDL-cholesterol were found on chromosome 1. Loci for other lipids with suggestive linkage were also identified. In both F2 mice, one QTL on chromosome 1 for total- and HDL-cholesterol was mapped near D1Mit150, in the vicinity of the apolipoprotein A-II (Apoa2) locus. Seven nucleotide substitutions out of 309 nucleotide apolipoprotein A-II cDNA sequences were identified between KK and C57BL/6J. The Ay allele may be an indication of the plasma lipid levels, but its influence was less apparent than in the case of weight control. The loci for lipids were not on identical chromosomes with those previously identified for obesity, suggesting that hyperlipidemia in KK does not coincidentally occur with obesity.

Measurement of urinary lactoferrin as a marker of urinary tract infection

The usefulness of the measurement of urinary lactoferrin (LF) released from polymorphonuclear leukocytes and of an immunochromatography test strip devised for measuring urinary LF for the simple and rapid diagnosis of urinary tract infections (UTI) was evaluated. Urine specimens were collected from apparently healthy persons and patients diagnosed as suffering from UTI. In the preliminary study, the LF concentrations in 121 normal specimens and 88 specimens from patients (60 with UTI) were quantified by an enzyme-linked immunosorbent assay. The LF concentration was 3,300.0 +/- 646.3 ng/ml (average +/- standard error of the mean) in the specimens from UTI patients, whereas it was 30.4 +/- 2.7 ng/ml and 60.3 +/- 14.9 ng/ml in the specimens from healthy persons and the patients without UTI, respectively. Based on these results, a 200-ng/ml LF concentration was chosen as the cutoff value for negativity. Each urine specimen was reexamined with the newly devised immunochromatography (IC) test strip to calculate the indices of efficacy. Based on the cutoff value, it was calculated that the sensitivity, specificity, and positive and negative predictive values of the IC test were 93.3, 89.3, 86.2, and 94.9%, respectively, compared with the results of the microscopic examination of the urine specimens for the presence of leukocytes. The respective indices for UTI were calculated as 95.0, 92.9, 89.7, and 96.6%. The tests were completed within 10 min. These results indicated that urine LF measurement with the IC test strip provides a useful tool for the simple and rapid diagnosis of UTI.

Effect of Am-80, a synthetic derivative of retinoid, on experimental arthritis in mice

Am-80 is a newly snythesized retinoid with the structure of one aromatic amide among retinobenzoic acids. It exhibits specific biological activities of retinoic acid such as the activation of cellular differentiation and proliferation. We investigated the effect of Am-80 on collagen-induced arthritis (CIA) in mice and the immunopharmacological action on the production of several cytokines in the in vitro and in vivo models. Am-80, at doses of 0.3, 1 and 3 mg/kg, significantly inhibited the severity and development of the arthritis index, progression of foot pad swelling, bone damage and histopathological alterations. Am-80 also inhibited the production of anti-type II collagen (CII) IgG antibody, but did not affect the delayed-type hypersensitivity (DTH) response in arthritic mice. To determine the inhibitory mechanism of Am-80, we studied the effect of Am-80 on the production of cytokines. Am-80 did not affect the production of IFN-gamma by Th1 cells (1E10.H2 cells) and IL-4 by Th2 cells (D10.G4.1 cells), respectively. Am-80 selectively inhibited bacterial lipopolysaccharide (LPS)-induced IL-6, but not TNF-alpha and IL-1beta, production in mice. Moreover Am-80 inhibited IL-1beta induced IL-6 production and IL-6 mRNA expression in human osteoblast-like cells (MG-63). The inhibition of IL-6 production by Am-80 was due to downregulation of the pretranscription or the transcription of IL-6 in MG 63 cells. These findings suggest that the inhibitory effect of Am-80 on CIA is partially by modulating the production of the proinflammatory cytokine, IL-6.

Sequence analysis of an 800-kb genomic DNA region on chromosome 8q21 that contains the Nijmegen breakage syndrome gene, NBS1

An 800-kb region on chromosome 8q21, which complements the phenotype of cells from Nijmegen breakage syndrome patients, is a candidate for the locus of the underlying gene, termed NBS1. The sequence of this 800-kb region of DNA indicated that the size of this segment is 755,832 bp with an additional 36-kb gap. From this region, we identified four genes including NBS1, a gene coding for a 27-kDa vitamin D-dependent calcium-binding protein (27-kDa calbindin), the mitochondrial 2,4-dienoyl-CoA reductase gene, and a novel gene, C8orf1/hT41. All four genes were aligned in a 250-kb centromeric portion of the region, and no gene was found in the remaining telomeric portion containing 500 kb. The genomic organization of the C8orf1/hT41 and NBS1 genes has been analyzed using the computer programs GRAIL 2 and GENSCAN. They predicted and successfully found more than 93% of the exons, even a small 54-bp exon, indicating that one or more exons in any gene can be identified by these programs. GENSCAN was more efficient at locating the four genes than GRAIL 2 and identified 15 of the 16 exons of the NBS1 gene. This 800-kb region contained repetitive sequences, including 179 copies of the Alu sequence (1 copy/4.2 kb), 123 copies of the L1 sequence (1 copy/6.1 kb), 107 copies of the LTR sequence (1 copy/7.1 kb), and 63 copies of the MER sequence (1 copy/12 kb). There was a slight but not significant difference in the repetitive content of the gene-rich region and the remaining noncoding region. Our results indicate that computer-assisted methods are useful and powerful for identifying exons of both known and novel genes.

T-cell lymphoma in a savanna monkey (Cercopithecus aethiops) probably related to simian T-cell leukemia virus infection

Lymphoma was seen in an 11-year-old female savanna monkey (Ceropithecus aethiops). The superficial inguinal and visceral lymph nodes were markedly enlarged, and their architecture was completely effaced by neoplastic cells. The neoplastic cells, which were highly pleomorphic, resembled those in adult T-cell lymphoma-leukemia in humans. Ultrastructurally the neoplastic cells were characterized by nuclear irregularity and clustered dense bodies, and almost all cells showed positivity for CD3. The animal had been reared with her family, and her mother and 2 brothers had antibodies reactive to human T-cell leukemia virus. This virus serologically cross-reacts with simian T-cell leukemia virus, which may be the causative agent of the present neoplasm.

Systemic hypotensive response to protamine following chronic inhibition of nitric oxide synthase in rats

PURPOSE

The aims of the present studies were to determine whether the systemic hypotensive response to protamine was modified in rats pre-treated for two weeks with the nitric oxide synthase inhibitor, NG-nitro-L-arginine-methyl ester (L-NAME), and to evaluate the inhibitory effect of heparin on the systemic hypotensive response to protamine in vivo.

METHODS

Male rats were randomly assigned into four groups. Normal saline 12 microliters.day-1, D-NAME (an inactive enantiomer of L-NAME), 10 mg.kg-1, L-NAME, 1 or 10 mg.kg-1.day-1 i.p. was administered for two weeks and the haemodynamic changes were measured after protamine administration. In another experiment, male rats were assigned to two groups. In one, the heparin group, protamine was administered after heparin had been administered and in the other, protamine group, protamine alone was administered.

RESULTS

L-NAME inhibited the decrease in systemic arterial pressure after protamine administration (P < 0.05), but D-NAME had no effect. Also, heparin reduced the decrease in systemic arterial pressure after protamine (P < 0.05).

CONCLUSION

Nitric oxide is mainly responsible for mediation of the systemic hypotensive response to protamine which is also reduced by heparin.

Genetic analysis of non-insulin-dependent diabetes mellitus in KK and KK-Ay mice

The KK mouse is considered suitable as a polygenic model for human non-insulin-dependent diabetes mellitus. To identify the quantitative trait loci (QTLs) responsible for hyperglycemia and impaired glucose tolerance in KK mice, linkage analysis using 97 microsatellite markers was carried out in a 192 F2 progeny, comprising 93 mice with the a/a genotype at the agouti locus (chromosome 2) and 99 mice with the Ay/a genotype, produced by a cross between a C57BL/6J female and a KK-Ay (Ay congenic) male. In F2 a/a progenies, we identified a QTL for fasting glucose levels on chromosome 6 (LOD score 6.0) and three loci with suggestive linkage on chromosomes 3, 5 and 14, but could not identify loci accounting for glucose tolerance and plasma insulin levels. In F2 Ay/a progenies, there were no loci with statistically significant linkage, but three suggestive loci were identified: a locus for fasting glucose on chromosome 9, and two loci for glucose tolerance on chromosomes 1 and 8. It would thus appear that. although the fasting glucose level is controlled by QTLs in KK mice, these QTLs may be masked by the strong hyperglycemic influence of the Ay allele. Suggestive loci accounting for glucose tolerance may interact with the Ay allele, since these loci were identified only in F2 Ay/a progeny. This is consistent with the finding that the impaired glucose tolerance in KK mice is moderate and becomes overt when associated with the Ay allele.

Volume-evoked micturition reflex is mediated by the ventrolateral periaqueductal gray in anesthetized rats

The central pathway of the micturition reflex in the rat was investigated functionally by acute blockade of synaptic neurotransmission using microinjection of cobalt chloride into the periaqueductal gray or pontine tegmental region. In 27 urethan-anesthetized (1.2 g/kg ip) rats, the bladder pressure response to continuous infusion of the bladder with saline (0.1-0.25 ml/min) was assessed. Electromyographic activity of external urethral sphincter and arterial blood pressure were also monitored. Bladder contractions and external urethral sphincter activity were reversibly attenuated after unilateral or bilateral stereotaxic injections of 10 mM cobalt chloride into the caudal (bregma -7.80 to -8.80) ventrolateral periaqueductal gray as well as into Barrington's nucleus. Blood pressure was not affected by injection into either area. The results demonstrate that the caudal ventrolateral periaqueductal gray, in addition to Barrington's nucleus, is a critical part of the long-routed micturition reflex circuitry in the anesthetized rat.

Identification of stable RNA hairpins causing band compression in transcriptional sequencing and their elimination by use of inosine triphosphate

To identify stable RNA secondary structure causing band compression, 30 lambda DNA clones and four cDNA clones (about 10 kb in total length) were sequenced using Transcriptional Sequencing, which is based on the phage RNA polymerase chain termination reaction with fluorescent 3' deoxynucleoside triphosphate, using the canonical set of rNTPs for the substrate. Electrophoresis was performed on acrylamide gel containing 7 M urea at 50 degrees C using ABI 377 DNA sequencer. A total of 159 band compressions were identified, and most compression sites seem to be due to hairpin structures. We also found that the presence of rITP in place of rGTP in the sequencing reaction can entirely eliminate all band compressions. The use of rITP gave a better peak uniformity and resolution in the sequencing gel in the case of lambda DNA than with c7rGTP, leading to improved accuracy in the sequence determination. Substitution of the base analog rITP for rGTP should be useful for accurate sequencing determination.

Estimation of dose absorbed fraction for 131I-beta rays in rat thyroid

The dose absorbed fraction of rat thyroid by internal deposit of 131I has been calculated as a function of effective diameter of thyroid. The calculations were done using two types of Monte Carlo simulations: one was by a simple energy-loss calculation in spherical volume according to the electron stopping power, and another by a more realistic simulation using Monte Carlo N-Particle Transport code system Version 4A (MCNP). These two calculations were consistent with each other within a deviation of 5%. The absorbed fractions in spherical thyroid were drastically changed up to 5 mm diameter, and then almost all energy was deposited within 10 mm diameter. For the practical application to the animal experiment, the absorbed fractions of ellipsoid-shaped thyroids were also calculated for 1-, 4- and 9-week-old rats, where the fractions were estimated to be 0.61, 0.67 and 0.68, respectively. It was also found that the absorbed fraction of the ellipsoid with various dimensions can be simulated by a calculation for spherical volume with a comparable effective diameter.

The treatment of neuroleptic malignant syndrome using dantrolene sodium

The use of dantrolene sodium (DS) in the treatment of neuroleptic malignant syndrome (NMS) was studied from the data of 21 cases of NMS, which satisfied the diagnostic criteria of Pope et al. The mean dosage of DS was 0.97+/-0.52 mg/kg per day and the mean duration of treatment was 8.3+/-5.3 days. It was confirmed that the mean duration of treatment with DS tended to be longer in the cases involving disturbance of consciousness. However, there were no significant differences in the duration of treatment or the mean daily dosage, in the cases without disturbance of consciousness regardless of any other complications and symptoms. Also, there were no significant differences in the mean duration of treatment using DS and the mean dosage of DS between five cases that were considered to be 'typical' and 16 cases that were considered to be 'incomplete'. In addition, the prognoses of these cases were good such that not even one death occurred. In 13 cases, the treatment of psychiatric symptoms with thioridazine was started without recurrence of NMS.

Gastric mucormycosis in a sika deer (Cervus nippon) associated with proliferation of Clostridium perfringens

Seven sika deer (Cervus nippon) died in a park where 30 deer were kept. One adult female deer died suddenly was necropsied. Severe hemorrhages were noted beneath the serous membranes of the forestomach and abomasum. Hyphal proliferation with neutrophil infiltration was observed in the mucous membranes of the stomaches, and the hyphae showed characteristics of order Mucorales. Catarrhal enteritis with hemorrhages was also observed. A large number of Clostridium perfringens was isolated from the contents of the abomasum and small intestine. The case was diagnosed as gastric mucormycosis associated with proliferation of Clostridium perfringens. The incidence occurred during breeding season and incorrect management was considered to be a predisposing factor for the infection.

Genetics of obesity in KK mouse and effects of A(y) allele on quantitative regulation

KK mouse is known as a polygenic model for noninsulin-dependent diabetes mellitus with moderate obesity. To identify the quantitative trait loci (QTLs) responsible for the body weight in KK, linkage analysis with 97 microsatellite markers was carried out into 192 F2 progeny, comprising 93 mice with a/a genotype at agouti locus and 99 mice with A(y)/a genotype, of a cross between C57BL/6J female and KK-A(y) (A(y) congenic) male, thereby the influence of A(y) allele on the quantitative regulation of body weight was also examined. In F2 a/a mice, we identified a QTL on Chromosome (Chr) 4, and two loci with suggestive linkage on Chrs 15 and 18. In F2 A(y)/a mice, a QTL was identified on Chr 6, and two loci with suggestive linkage were identified on Chrs 4 and 16. That the QTL on Chr 4 was held in common between F2 a/a and F2 A(y)/a progenies implies that this locus may be a primary component regulating body weight in KK and KK-A(y). These results suggest that the body weight in KK is controlled by multiple genes, and the different combination of loci is involved in the presence of A(y) allele. The QTL on Chr 6 seemed to determine the body weight by controlling fat deposition, because the linkage was identified on body weight and adiposity, and is suggested to be a component involved in the metabolic pathway in obesity caused by the A(y) allele.