Active-type starch synthase (SS) IIa from indica rice partially complements the sugary-1 phenotype in japonica rice endosperm.

KEY MESSAGE: Introduction of higher SSIIa activity to mild-type isa1 mutant by crossing results in restoration of crystallinity, starch granule structure, and production of plump seeds. Isoamylase 1 (ISA1) removes improper α-1, 6 glycosidic branches of amylopectin generated by starch branching enzymes and is essential for the formation of proper amylopectin structure. Rice isa1 (sug-1) mutants in japonica cultivar with less-active starch synthase IIa (SSIIa) and low granule-bound SSI (GBSSI) expression display wrinkled seed phenotype by accumulating water-soluble phytoglycogen instead of insoluble amylopectin. Expression of active SSIIa in transgenic rice produced with a severe-type isa1 mutant accumulated some insoluble glucan with weak B-type crystallinity at the periphery of seeds but their seeds remained wrinkled. To see whether introduction of high levels of SSIIa and/or GBSSI can restore the grain filling of the mild-type sug-1 mutant (EM653), new rice lines (SS2a gbss1L isa1, ss2aL GBSS1 isa1, and SS2a GBSS1 isa1) were generated by crossing japonica isa1 mutant (ss2aL gbss1L isa1) with wild type indica rice (SS2a GBSS1 ISA1). The results showed that SS2a gbss1L isa1 and SS2a GBSS1 isa1 lines generated chalky plump seeds accumulating insoluble amylopectin-like glucans with an increase in DP 13-35, while ss2aL GBSS1 isa1 generated wrinkly seeds and accumulated soluble glucans enriched with DP < 13. Scanning electron microscopic observation of cross-section of the seeds showed that SS2a gbss1L isa1 and SS2a GBSS1 isa1 produced wild type-like polygonal starch granules. These starches showed the A-type crystallinity comparable to the wild type, while the japonica isa1 mutant and the transgenic rice do not show any or little crystallinity, respectively. These results indicate that introduction of higher SSIIa activity can mostly complements the mild-type sug-1 phenotype.

Contrast enhancement efficacy of iodinated contrast media: Effect of molecular structure on contrast enhancement.

PURPOSE: To investigate the contrast enhancement in DSA images based on the X-ray absorption characteristics of iodinated contrast media. METHODS: We have derived a new formula of predicting the pixel value ratio of two different contrast media and designate it as "Contrast Enhancement Ratio (CER)". In order to evaluate the accuracy of CER, we have evaluated the relationship between CER and pixel value ratio for all combinations of eleven iodinated contrast media. The non-ionic iodinated contrast media, iopamidol, iomeprol, iopromide, ioversol, iohexol, and iodixanol, were evaluated in this study. Each contrast medium was filled in the simulated blood vessel in our constructed anthropomorphic phantom, and DSA images were obtained using an angiographic imaging system. To evaluate the contrast enhancement of the contrast medium, the mean pixel value was calculated from all pixel values in the vascular image. RESULTS: CER was indicated to agree well with the pixel value ratio of two different contrast medium solutions and showed a good accuracy. CER was also shown to have a good linear relation to the pixel value ratio when the iodine concentration was constant. This means that the molecular structure of the contrast media affects contrast enhancement efficacy. Furthermore, in evaluation of contrast enhancement of iodinated contrast media by using the weight factor (that is a key factor in CER) ratio, Iodixanol, and iopamidol, and iomeprol have the same ability of contrast enhancement in DSA images, and iohexol shows the lowest ability. CONCLUSIONS: We have derived a new formula (CER) of predicting the pixel value ratio of two different contrast medium solutions, and shown that CER agreed well with the pixel value ratio for blood vessel filled with eleven contrast media.

Polysaccharide K suppresses angiogenesis in colon cancer cells.

The protein-bound polysaccharide K (PSK) is used as a non-specific immunotherapeutic agent for the treatment of colon cancer. Little research, however, has been conducted on its association with angiogenesis, which is a prognostic factor markedly correlated with hematogenous metastases. We therefore decided to investigate the action of PSK on angiogenic growth factors, angiogenesis inhibitors and angiogenesis in colon cancer cells. Reverse transcription-polymerase chain reaction (RT-PCR) was used to investigate changes in HIF-1α mRNA expression. PCR array was used to investigate changes in angiogenic growth factors and angiogenesis inhibitors, as well as the expression of related genes. Colon cancer cells were cultured with or without PSK for 48 h. The following day, cells were cultured for two days at 37°C in new complete media. The resulting culture medium was placed in the chamber of a tube formation system in order to investigate tube formation. Investigation of HIF-1α mRNA expression in colon cancer cell lines and in cells cultured under identical conditions with added PSK revealed a significant decrease in expression, as well as a decrease in angiogenic growth factors and related genes in PSK-treated colon cancer cell lines. By contrast, levels of angiogenesis inhibitors and related genes were higher in the PSK-treated colon cancer cell lines. Investigation of tube formation revealed that elongation was inhibited in the medium of the PSK-treated colon cancer cell lines in comparison to the medium of the non-treated colon cancer cell lines. PSK suppresses angiogenic growth factors and related genes, enhances angiogenesis inhibitors and related genes and ultimately suppresses angiogenesis in colon cancer cells.

Angiogenesis and tumor proliferation/metastasis of human colorectal cancer cell line SW620 transfected with endocrine glands-derived-vascular endothelial growth factor, as a new angiogenic factor.

Endocrine glands-derived-vascular endothelial growth factor (EG-VEGF) was recently cloned as a new angiogenic factor that selectively acts on the endothelium of endocrine gland cells. We evaluated the involvement of EG-VEGF in colorectal cancer. The expression of EG-VEGF was confirmed in all of the colorectal cancer cell lines. (On the other hand, the expression of EG-VEGF mRNA was not detected in colorectal normal mucosae.) Stable EG-VEGF infectors of colorectal cancer cell line SW620 were produced, EG-VEGF transfectants were implanted into cecum and s.c., and cell proliferation was evaluated. Angiogenesis was evaluated by dorsal air sac method. Liver metastasis was evaluated after the implantation of EG-VEGF transfectants into the mouse spleen. Tumor proliferation (cecum, s.c.) was significantly higher in the EG-VEGF transfectants than in the control cells. The small vessels were significantly increased in EG-VEGF transfectants as compared with those in control cells. Also, liver metastatic ratio was higher in the EG-VEGF transfectants than in the control cells. In this study, EG-VEGF, a new angiogenic factor, may lead to angiogenesis, promoting cell proliferation and liver metastasis in colorectal cancers. When the EG-VEGF gene-overexpressing colorectal cancer cell line that had been treated with phosphorothioate antisense EG-VEGF oligonucleotides was injected s.c. into mice, angiogenesis and tumor growth were inhibited. Although the novel angiogenesis factor EG-VEGF was not expressed in the normal colorectal mucosa, it was expressed in colorectal cancer cells, which indicates that it is a cancer-specific and possibly tissue-specific angiogenesis factor in the large intestine, and which suggests that it can be targeted by a novel antiangiogenesis therapy.