Dielectric characteristics of oil‐filled transformer in the presence of nonstandard lightning surge waveforms

To achieve a rational insulation design for transformers, it is important to evaluate dielectric strength against surges actually impinging on equipment on‐site. This paper deals with the breakdown voltage characteristics of an oil gap under nonstandard lightning surge waveforms combined with oscillatory voltages. It is found that the breakdown voltages of the oil gap under nonstandard impulse waveforms are higher than standard lightning impulse voltages. The results can be ascribed to V–t characteristics of the oil gap in short‐time impulse voltage ranges. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 146(3): 39–45, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10229     

Insulation characteristics of SF6 gas for nonstandard impulse voltage polarity reversal pulse waveforms

Evaluation of insulation strength for lightning surge that actually enters into substations is important in estimating insulation reliability of gas‐insulated equipment. The standard lightning impulse voltage (1.2/50 µs) is used for factory tests. However, the actual lightning surge waveforms in substations are complex and are usually superimposed with various oscillations. Insulation characteristics of SF₆ gas as a function of such complex voltages have not been sufficiently clarified. This paper deals with gap breakdown characteristics in SF₆ gas under submicrosecond pulses. Breakdown voltages are lower under a polarity reversal condition than under a monopolarity condition. The cause of this difference is discussed while observing discharge propagation using an image converter camera. The electrode size effect is also discussed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 146(4): 18–25, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10246     

Evolutionarily conserved mechanisms regulating neural development: lessons from the development of Drosophila peripheral nervous systems

Functions of genes regulating the development of Drosophila peripheral nervous systems are summarized herein. These genes can be classified into 6 groups: <1> prepattern genes, <2> proneural genes, <3> neurogenic genes, <4> neuronal precursor genes, <5> neuronal precursor type selector genes, and <6> cell-division and lineage genes. The mechanisms described herein provide excellent paradigms in the regulation of the development of other tissues in Drosophila, as well as in other organisms, including vertebrates. The roles of two different inhibitory mechanisms, i.e. Notch-signaling and Argos, in the development of Drosophila neural precursor cells are also discussed.     

Twist form of teleocidin derivatives is active in in vivo tumor promotion by (-)-benzolactam-V8-310

Two patients, both 70 years old, operated for differentiated thyroid cancer with foci of undifferentiated tumor (one papillary containing pseudosarcomatoid foci, the other with insular pattern containing undifferentiated foci) suddenly died. In both cases, for both of them metastatic involvement of the myocardium and endocardium. These original findings suggest that elderly patients suffering rom well differentiated thyroid cancer, containing undifferentiated foci, therefore suspected to have metastasized, would benefit from non-invasive cardiac work-up (sonogram) in order to plan their multidisciplinary treatment.     

Stability of metallothionein isoforms by capillary zone electrophoresis

Advanced glyco-oxidation end products (AGEs) generate oxygen free radicals that potentiate the development of atherosclerosis. Thus, AGEs may potentiate the aggregation of human platelets through oxidative stress. AGE-bovine serum albumin (BSA) and AGE-poly-L-lysine were evaluated for aggregation of human platelets. Superoxide in platelet-rich plasma (PRP) was measured using lucigenin-derived chemiluminescence. The platelet aggregation induced by ADP or U46619 was potentiated by preincubation with AGE-BSA, by 40% and by 59%, P < .05, respectively, vs BSA. Aggregation was increased by AGEs in a dose-dependent manner. The production of superoxide was significantly greater in PRP incubated with AGE-BSA vs BSA. The other Maillard reaction products, such as Amadori-, pentosidine-, and carboxymethyl lysine (CML)-BSA had no effect. Superoxide dismutase or indomethacin abolished the enhancing effect of AGEs on the platelet aggregation. AGEs potentiate platelet aggregation possibly with superoxide anions and prostanoids. AGE-induced potentiation of platelet aggregation may be involved in the development of atherosclerosis.     

Autologous bone marrow transplantation in children with advanced neuroblastoma

BACKGROUND: Encouraging results have been reported with high dose chemotherapy and total body radiation followed by bone marrow autotransplantation in children with advanced neuroblastoma; however, relapse remains a significant problem. METHODS: The authors treated 22 children with advanced neuroblastoma with high dose chemotherapy, surgery, intraoperative radiation, and a bone marrow autotransplant (treated in vitro to remove tumor cells) followed by 13-cis-retinoic acid. RESULTS: The 3-year relapse rate was 25% (95% confidence interval [CI], 6-44%). The 3-year disease free survival rate was 72% (95% CI, 52-92%). Toxicities included hemolytic uremic syndrome, herpes infection, and hepatic venoocclusive disease. CONCLUSION: These data suggest that this treatment strategy offers an increased rate of 3-year disease free survival. The nonrandomized nature of this study and its use of multiple modalities precludes the analysis of the specific contribution of each treatment component and comparison with conventional therapy.     

Glycosylphosphatidylinositol-anchor-deficient mice: implications for clonal dominance of mutant cells in paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by complement-mediated hemolysis. Abnormal hematopoietic cells from patients with PNH are deficient in glycosylphosphatidylinositol (GPI)-anchored proteins and clonally dominate various hematopoietic lineages in the bone marrow and the peripheral blood. Analysis of many patients with PNH has showed that somatic mutation in the X-linked gene PIG-A is responsible for the GPI-anchor deficiency in PNH. The PIG-A mutation must also be relevant to the clonal dominance of GPI-anchor deficient (GPI-) blood cells because two or more PIG-A mutant clones become dominant in many patients. However, whether the PIG-A mutation alone is sufficient for clonal dominance is not known. To address this question, we generated chimeric mice using Pig-a (the murine homologue of PIG-A) disrupted embryonic stem (ES) cells, in which the animals are chimeric with respect to the surface expression of GPI-anchored proteins. The chimerism of hematopoietic and nonhematopoietic tissues in such mice was always low, suggesting that the higher contribution of Pig-a disrupted GPI- cells had a lethal effect on the chimera. GPI- cells appeared in the peripheral blood of some of the chimeric mice. However, the percentage of GPI- erythrocytes did not increase for 10 months after birth, implying that the Pig-a mutation alone does not immediately cause the clonal dominance of GPI- blood cells; another pathologic or physiologic change(s) in the hematopoietic environments or in the clone itself may be necessary.     

Twelve cases of systemic lupus erythematosus in boys]

We compared clinical findings in 12 cases of systemic lupus erythematosus (SLE) in boys with those in 49 cases in girls. The age at which SLE developed in boys was consistent with that of infantile SLE and there was no age specificity. Momy cases in boys were diagnosed earlier as compared with cases in girls. Symptoms of infantile SLE, such as fever, arthalgia, butterfly rash, and urinary abnormalities, did not differ between boys and girls. However, a higher percentage of boys (58.3%) had central nervous system complications at onset than did girls (30.6%). Platelet counts tended to be higher in boys than in girls, a finding that suggests SLE tends to be more severe in boys than in girls. The incidence in the appiarance of LE cells, anti-Sm antibodies and immune complexes was higher in boys than in girls. Type IV or V renal pathologic changes (World Health Organization Histologic Classification) were present in 70% of boys. Our findings suggest that SLE in boys is more severe than that in girls and is more likely to be associated with central nervous system complications and severe renal complications.     

Potent preventive action of alpha-carotene against carcinogenesis: spontaneous liver carcinogenesis and promoting stage of lung and skin carcinogenesis in mice are suppressed more effectively by alpha-carotene than by beta-carotene

Although beta-carotene has been considered to be a key cancer preventive agent in green and yellow vegetables, other types of carotenoids, such as alpha-carotene, may also contribute to anticarcinogenic action, since these carotenoids usually coexist with beta-carotene and are detectable in human blood and tissues. In this study, we compared the inhibitory effect of natural alpha-carotene, obtained from palm oil, with that of beta-carotene on spontaneous liver carcinogenesis in C3H/He male mice. The mean number of hepatomas per mouse was significantly decreased by alpha-carotene supplementation (per os administration in drinking water at a concentration of 0.05%, ad libitum) as compared with that in the control group (P < 0.001, Student's t test). On the other hand, beta-carotene, at the same dose as alpha-carotene, did not show any such significant difference from the control group. Furthermore, we also compared the antitumor-promoting activity of alpha-carotene with that of beta-carotene against two-stage mouse lung carcinogenesis (initiator, 4-nitroquinoline 1-oxide; promoter, glycerol). alpha-Carotene, but not beta-carotene, reduced the number of lung tumors per mouse to about 30% of that in the control group (P < 0.001, Student's t test). The higher potency of the antitumor-promoting action of alpha-carotene compared to beta-carotene was confirmed in other experimental systems; e.g., alpha-carotene was also found to have a stronger effect than beta-carotene in suppressing the promoting activity of 12-O-tetradecanoylphorbol-13-acetate on skin carcinogenesis in 7,12-dimethylbenz[a]anthracene-initiated mice. These results suggest that not only beta-carotene, but also other types of carotenoids, such as alpha-carotene, may play an important role in cancer prevention.