CO2-cAMP-Responsive cis-Elements Targeted by a Transcription Factor with CREB/ATF-Like Basic Zipper Domain in the Marine Diatom Phaeodactylum tricornutum1[W][OA]

Expression controls of the carbon acquisition system in marine diatoms in response to environmental factors are an essential issue to understand the changes in marine primary productivity. A pyrenoidal β-carbonic anhydrase, PtCA1, is one of the most important candidates to investigate the control mechanisms of the CO2 acquisition system in the marine diatom Phaeodactylum tricornutum. A detailed functional assay was carried out on the putative core regulatory region of the ptca1 promoter using a β-glucuronidase reporter in P. tricornutum cells under changing CO2 conditions. A set of loss-of-function assays led to the identification of three CO2-responsive elements, TGACGT, ACGTCA, and TGACGC, at a region −86 to −42 relative to the transcription start site. Treatment with a cyclic (c)AMP analog, dibutyryl cAMP, revealed these three elements to be under the control of cAMP; thus, we designated them, from 5′ to 3′, as CO2-cAMP-Responsive Element1 (CCRE1), CCRE2, and CCRE3. Because the sequence TGACGT is known to be a typical target of human Activating Transcription Factor6 (ATF6), we searched for genes containing a basic zipper (bZIP) region homologous to that of ATF6 in the genome of P. tricornutum. Gel-shift assays using CCRE pentamers as labeled probes showed that at least one candidate of bZIP proteins, PtbZIP11, bound specifically to CCREs. A series of gain-of-function assays with CCREs fused to a minimal promoter strongly suggested that the alternative combination of CCRE1/2 or CCRE2/3 at proper distances from the minimal promoter is required as a potential target of PtbZIP11 for an effective CO2 response of the ptca1 gene

Changes in risk of immediate adverse reactions to iodinated contrast media by repeated administrations in patients with hepatocellular carcinoma.

BACKGROUND: To elucidate whether repeated exposures to iodinated contrast media increase the risk of adverse reaction. MATERIALS AND METHODS: We retrospectively reviewed 1,861 patients with hepatocellular carcinoma who visited authors' institution, a tertiary referral center, between 2004 and 2008. We analyzed cumulative probability of adverse reactions and risk factors. We categorized all symptoms into hypersensitivity reactions, physiologic reactions, and other reactions, according to the American College of Radiology guidelines, and evaluated each category as an event. We estimated the association between hazard for adverse reactions and the number of cumulative exposures to contrast media. We also evaluated subsequent contrast media injections and adverse reactions. RESULTS: There were 23,684 contrast media injections in 1,729 patients. One hundred and thirty-two patients were excluded because they were given no contrast media during the study period. Adverse reactions occurred in 196 (0.83%) patients. The cumulative incidence at 10(th), 20(th), and 30(th) examination was 7.9%, 15.2%, and 24.1%, respectively. Presence of renal impairment was found to be one of risk factors for adverse reactions. The estimated hazard of overall adverse reaction gradually decreased until around 10(th) exposure and rose with subsequent exposures. The estimated hazard of hypersensitivity showed V-shaped change with cumulative number of exposures. The estimated hazard of physiologic reaction had a tendency toward decreasing and that of other reaction had a tendency toward increasing. Second adverse reaction was more severe than the initial in only one among 130 patients receiving subsequent injections. CONCLUSION: Repeated exposures to iodinated contrast media increase the risk of adverse reaction

The smoothed plots of the estimated hazard of overall and each reactions to iodinated contrast media.

<p>The curves illustrate smoothed plot of the estimated hazard of (A) overall adverse reactions, (B) hypersensitivity, (C) physiologic and (D) other adverse reaction to iodinated contrast media in patients with no previous exposure to contrast media. The hazard function (solid line) and 95% confidence intervals (black dotted line) were estimated by a smoothing spline with three knots. Gray dotted lines show the hazard at the initial exposure.</p

The cumulative probabilities of overall and each reactions to iodinated contrast media.

<p>Graphs illustrate (A) the cumulative probability of overall adverse reactions to iodinated contrast media and (B) the cumulative probabilities of hypersensitivity, physiologic and other adverse reactions to iodinated contrast media.</p

Subsequent contrast media injections and subsequent adverse reaction to iodinated contrast media.

<p>Subsequent contrast media injections and subsequent adverse reaction to iodinated contrast media.</p