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R Ogata

Publications and source records attributed to R Ogata.

43 records · Page 3Linked to original sources
PubMed1977

Contacts between the lac repressor and the thymines in the lac operator.

We have identified important points of contact between the lac repressor and the lac operator by crosslinking the repressor to bromouracil-substituted operator. We substituted bromouracils for thymines in a 55-base-long restriction fragment containing the lac operator and labeled one or the other 5' end with 32P. Ultraviolet irradiation of this fragment produced single-strand breakds at the bromouracils. We examined breakage at each bromouracil in the sequence by denaturing the DNA and displaying the UV-generated fragments on a polyacrylamide gel. In the presence of lac repressor, UV radiation failed to break at specific sites. We attribute this to a competing reaction in which the DNA crosslinks to the repressor rather than breaking. These crosslinkable sites thus define positions at which the lac repressor protein lies close to the methyl group of a thymine in the major groove of DNA.

Base Sequence↗
PubMedDate not supplied

A simultaneous monitoring of Lens culinaris agglutinin A-reactive alpha-fetoprotein and des-gamma-carboxy prothrombin as an early diagnosis of hepatocellular carcinoma in the follow-up of cirrhotic patients.

To elucidate the risk factors for developing hepatocellular carcinoma (HCC) during the follow-up of patients with liver cirrhosis (LC), outpatients with LC were examined periodically by means of serum biochemical assessments, ultrasonography, and computed tomography. Risk factors for HCC were statistically analyzed. We also examined an efficacy of Lens culinaris agglutinin A-reactive profiles of alpha-fetoprotein (AFP-L3%) and des-gamma-carboxy prothrombin (DCP) value using a highly sensitive DCP determination kit (ED036) for the early recognition of HCC. The AFP-L3% and the ED036 value were retrospectively determined with stored serum samples. HCC was diagnosed in 21 of the 78 patients with LC during the follow-up period (mean follow-up period: 42 months). The estimated cumulative incidence of HCC was 25% with 3 years and 48% with 5 years. The most significant risk factor for the development of HCC in LC patients was found to be the mean serum AFP concentration from the year before the HCC detection (p=0.02). At the time of the recognition of HCC, the positive rates of the tumor markers were: serum AFP concentration 14%, serum DCP value 5%, AFP-L3% was 33%, and that of ED036 43%. The positive rate in collaborative use of AFP-L3% and ED036 was 67%. The simultaneous determination of the AFP-L3% and the ED036 value was shown to be effective for the early detection of HCC.

Aged↗
PubMedDate not supplied

Bright loop appearance; a characteristic ultrasonography sign of early hepatocellular carcinoma.

Ultrasonography (US) and computed tomography (CT) are the most effective screening methodologies for hepatocellular carcinoma (HCC). In our US screening, 20% of small HCC nodules less than 20 mm in diameter were detected as hyperechoic tumors. Among these hyperechoic HCC nodules, we have often observed (BL) which is defined as hypoechoic nodules in the hyperechoic tumor. In this study, we report that the BL is a sign of dedifferentiation of early stage of HCC with fatty change by US. From 1994 to 1998, we performed tumor targeting needle biopsy in 938 hepatic nodular lesions. Among them, 284 nodules <20 mm in diameter, histologically diagnosed as HCC, were studied. BL is defined as a hyperechoic tumor containing a hypoechoic nodule >4 mm in diameter by US. Among 284 nodules, well, moderately and poorly differentiated HCC were 183 (64.4%), 100 (35.2%) and 1 (0.4%), respectively. On US, hypoechoic, isoechoic, and hyperechoic nodules were 188 (66.2%), 32 (11.3%) and 64 (22.5%), respectively. Forty-seven nodules of 64 hyperechoic HCC nodules <20 mm in diameter, 47 nodules (73.4%) showed fatty changes. Of 64 hyperechoic HCC nodules, we recognized 22 nodules (34.4%) as BL. The proportion of BL type hyperechoic nodules increased with the tumor size. Two hyperechoic nodules followed by US changed to BL with tumor enlargement. Histologic examination of a resected HCC with BL showed that hyperechoic HCC nodule represented well-differentiated HCC with fatty change and inner hypoechoic lesion represented moderately differentiated HCC without fatty change. In US screening for HCC, BL was often observed in HCC nodules from 11 to 20 mm in diameter. Histologic examination revealed that BL of HCC on US was associated with tumor progression and indicated dedifferentiation showing moderately differentiated HCC in well-differentiated HCC with fatty change.

Adult↗