Biomedical subjects

Yoshiro Niitsu

Publications and source records attributed to Yoshiro Niitsu.

112 records · Page 7Linked to original sources

PubMed1999

Spontaneous appearance of circular actin bands in cultured hepatocytes of adult rats.

We demonstrated, using the phase-contrast microscope, fluorescence microscope, and scanning electron microscope, that circular actin bands appeared spontaneously on the dorsal surface of primary cultured hepatocytes of adult rats on days 2 and 3 of culture. These circular bands protruded from the dorsal surfaces of hepatocytes, the walls of which were very smooth and 2-3 &mgr;m in thickness. These structures were strongly stained with rhodamine-phalloidin (F-actin staining), and detected mainly in the areas in which cells were sparse. In number, these circular actin bands were very few on the first day of culture, more than 4000 per 35-mm dish on the second day, about 1500 on the third day, and very few on the fourth day. When insulin was omitted beginning 1 day after culture, the circular actin bands did not decrease in number. In serum-free medium, the number of circular actin bands decreased, although a considerable number of circular actin bands were observed. Wortmannin, a phosphatidylinositol 3-kinase (PI3K) inhibitor, completely inhibited the formation of spontaneously appearing circular actin bands within 10 min. These results indicate that PI3K plays a pivotal role in the formation of circular actin bands.

Journal Article↗

PubMedDate not supplied

BRCA1 transcriptionally regulates damaged DNA binding protein (DDB2) in the DNA repair response following UV-irradiation.

The p53 and BRCA1 tumor suppressors are involved in repair processes and may cooperate to transactivate certain genes, including p21WAF/CIP1 and GADD45. We find that the Xeroderma Pigmentosum Complementation group E (XPE) mutated Damaged-DNA binding protein p48 (DDB2) is upregulated by BRCA1 in a p53-dependent manner following UVC, Adriamycin, or Cisplatin exposure. BRCA1 enhances p53 binding to the DDB2 promoter in vivo as well as p53-dependent transactivation of DDB2 promoter-reporter constructs through a classical p53 DNA responsive element. Antisense abrogation of BRCA1 expression abrogates upregulation of DDB2 after UVC or cisplatin exposure. Using a host cell reactivation assay, DNA repair activity is more significantly restored by introduction of BRCA1 into wt as compared to DDB2-deficient cells. Furthermore disappearance of the photoproducts cyclobutane pyrimidine dimer (CPD) and 6-4 photoproduct (6-4PP) was delayed by antisense abrogation of BRCA1 expression in UV-exposed human cells. Thus the DNA repair function of BRCA1 may be attributed in part to p53-dependent transcriptional induction of DDB2. Loss of BRCA1-dependent DDB2 repair function may contribute to cancer susceptibility and cellular sensitivity to DNA damage.

Cell Survival↗

PubMedDate not supplied

Superselective transcatheter embolization for acute lower gastrointestinal hemorrhage after endoscopic mucosal resection: a report of 3 cases.

One of the most common complications related to endoscopic mucosal resection is hemorrhage; in almost every case, the bleeding is endoscopically managed, but some cases are unresponsive to the treatment. We have encountered three cases of endoscopically uncontrollable lower gastrointestinal hemorrhage after endoscopic mucosal resection in the colon which we successfully treated by urgent superselective transcatheter embolization. In our three cases, massive hemorrhage occurred immediately after endoscopic mucosal resection of a sessile polyp 25-40 mm in diameter, two cases in the ascending colon and one in the rectum. Although hemoclip placement was attempted in every case, hemostasis was not achieved. Emergency angiography disclosed massive extravasation of the contrast material in the colon. Hemostasis was achieved immediately after superselective transcatheter arterial embolizations with microcoils, with no observable ischemic complications and without the need of transfusions. In conclusion, superselective transcatheter embolization with microcoils should be considered a safe and efficient treatment option for endoscopically uncontrollable lower gastrointestinal hemorrhage occurring after endoscopic mucosal resection.

Aged↗

PubMedDate not supplied

A comparative randomized trial of intermittent intrahepatic arterial carboplatin- versus doxorubicin-lipiodol emulsion in advanced hepatocellular carcinoma (stage IV).

BACKGROUND/AIMS: The study was performed to investigate the anti-tumor effect, survival rate, and toxicity of intermittent intrahepatic infusion chemotherapy with carboplatin suspended in lipiodol. METHODOLOGY: We conducted a randomized controlled study containing either doxorubicin or carboplatin in 65 patients with advanced hepatocellular carcinoma. RESULTS: The results observed in the carboplatin- and doxorubicin-lipiodol groups included: response rates, 29.0 and 20.6% respectively, 1-year survival rates of, 60.4% and 40.4%, respectively, and the difference achieved statistical significance (p=0.025). The median survival of 31 patients who received carboplatin emulsified with lipiodol was 16.9 months, 34 patients who received doxorubicin was 12.1 months. The difference achieved statistical significance. CONCLUSIONS: Compared with doxorubicin, carboplatin caused neither cardiotoxicity nor nephrotoxicity, and side effects of nausea and vomiting were less severe. Therefore, carboplatin is effective and preferable for repeated intrahepatic arterial administration to treat advanced hepatocellular carcinoma over a relatively long period.

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