Namiko Suda

Seaweed Prevents Breast Cancer

To investigate the chemopreventive effects of seaweed on breast cancer, we have been studying the relationship between iodine and breast cancer. We found earlier that the seaweed, wakame, showed a suppressive effect on the proliferation of DMBA (dimethylbenz(a)anthracene)‐induced rat mammary tumors, possibly via apoptosis induction. In the present study, powdered mekabu was placed in distilled water, and left to stand for 24 h at 4°C. The filtered supernatant was used as mekabu solution. It showed an extremely strong suppressive effect on rat mammary carcinogenesis when used in daily drinking water, without toxicity. In vitro, mekabu solution strongly induced apoptosis in 3 kinds of human breast cancer cells. These effects were stronger than those of a chemothera‐peutic agent widely used to treat human breast cancer. Furthermore, no apoptosis induction was observed in normal human mammary cells. In Japan, mekabu is widely consumed as a safe, inexpensive food. Our results suggest that mekabu has potential for chemoprevention of human breast

Clinical Evaluation of Dual Mode Tomosynthesis

Clinical performance achieved by adding interpretation of Tomosynthesis images to 2D images (hereinafter 2D+Tomo) was studied. 100 cases who gave written informed consent (ST mode: angular range ±7.5deg, 50 cases and HR mode: ±20deg, 50 cases) were obtained and 7 radiologists interpreted all images. In ST, the sensitivity is significantly increased by 15% (P<.01) and specificity is equivalent (P=.73). In HR, sensitivity of 2D+Tomo against 2D alone is significantly increased by 30% (P<.001) and specificity is significantly decreased by 5% (P<.01). ST, which has higher sensitivity and equivalent specificity, can be used for screening, and HR, which can visualize structures such as lesions in details, can be used for diagnosis. Moreover, specificity enhancement due to inhibition of false positive and sensitivity enhancement are confirmed by trial for appropriate segmentation in Japanese category classification C3. Further detailed clinical performance will be studied such as in ROC analysis with more cases.

Function of the loop residue Thr792 in human DNA topoisomerase IIα

We studied the mutation effect of one of the putative loop residues Thr792 in human DNA topoisomerase II alpha (TOP2 alpha). Thr792 mutants were expressed from high or low copy plasmids in a temperature sensitive yeast strain deficient in TOP2 (top2-1). When expressed from a high copy plasmid, mutants with small side chains complemented the yeast defect; however, from a low copy plasmid, only wild-type, Ser, and Cys substitution mutants complemented the yeast defect. Interestingly, at the permissive temperature other mutants (e.g., Val, Gly, and Glu substitutions) showed the dominant negative effect to the top2-1 allele, which was not observed by the control alpha 4-helix mutants. T792E mutant was 10-fold less active than wild-type and the T792P had no decatenation activity in vitro. These results suggest that Thr792 in human TOP2 alpha is involved in enzyme catalysis.