A large pedunculated left ventricular thrombus with recurrent systemic thromboembolism in a young man.
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Biomedical subjects
D S Choi
Publications and source records attributed to D S Choi.
Spiral CT for the detection of hepatocellular carcinomas:relative value of arterial- and late-phase scanning.
BACKGROUND: Spiral computed tomography (CT) can image the liver during arterial and late phases of contrast and optimize the evaluation of hypervascular tumor. The objective of this study was to evaluate the relative value of arterial- and late-phase spiral CT in the detection of hepatocellular carcinomas. METHODS: Fifty-eight patients with hepatocellular carcinomas underwent two-phase spiral CT examination with 10-mm collimation at 10 mm/s table speed (Siemens Somatom Plus S), and 120 mL of contrast material (36 g iodine) was injected at the rate of 3 mL/s. CT images of hepatic arterial and late phases were obtained with a 35-s and 180-s delay, respectively. RESULTS: In 58 patients, 111 hepatocellular carcinoma lesions were seen. The arterial phase detected 93 (84%) and the late phase 75 (68%) lesions (p < 0.01). The arterial phase detected more lesions in 11 patients, and the late phase detected more in two patients and an equal number in 45 patients. If lesions larger than 2 cm are excluded, the arterial phase detected 40 (74%) and the late phase 21 (39%) of 54 lesions (p < 0.001). CONCLUSION: The arterial phase of spiral CT greatly improves the detection of hepatocellular carcinoma when compared with the late phase.
Adult↗
Rat ovarian insulin-like growth factor binding protein-4: a hormone-dependent granulosa cell-derived antigonadotropin.
OBJECTIVE: To assess the in vivo regulation of ovarian insulin-like growth factor binding protein-4 (IGFBP-4) mRNA expression by gonadotropins and estrogen. METHODS: Whole ovarian RNA, obtained from two models of follicular development, was extracted and analyzed by Northern blotting. Immature rats were treated with pregnant more serum gonadotropin (PMSG) followed 48 hours later with hCG, or alternatively were hypophysectomized and treated with FSH and/or diethylstilbestrol (DES). Localization of IGFBP-4 expression was assessed in the former study by in situ hybridization. Finally, the ability of human IGFBP-4 to antagonize FSH-stimulated progesterone accumulation was assessed in vitro. RESULTS: The ovarian content of IGFBP-4 transcripts increased threefold (P < .05) at 12 hours after PMSG but was near baseline at 24 and 48 hours. The abundance of IGFBP-4 mRNA increased (P < .05) again at 6 and 24 hours after hCG. The expression of IGFBP-4 was localized to granulosa cells of preantral (untreated) and small antral (12 hours after PMSG) follicles. No IGFBP-4 expression was noted in large (gonadotropin-primed) antral follicles. Hypophysectomy increased (P < .05) the ovarian content of IGFBP-4 mRNA by 1.5-fold, an effect further enhanced (1.8-fold; P < .05) by the provision of FSH and DES. In vitro studies revealed the ability of increasing concentrations (0.01-1 microgram/mL) of recombinant human IGFBP-4 to inhibit the FSH-supported accumulation of progesterone. CONCLUSION: Increased expression after administration of PMSG, hCG, and FSH/DES suggests that IGFBP-4 is a dynamic and hormonally responsive component of the ovarian cycle. The lack of expression in preovulatory follicles and its antigonadotropic actions in vitro imply that the attenuated expression of IGFBP-4 may constitute a requirement for successful follicular maturation.
Animals↗
Functional MR imaging of working memory in the human brain.
OBJECTIVE: In order to investigate the functional brain anatomy associated with verbal and visual working memory, functional magnetic resonance imaging was performed. MATERIALS AND METHODS: In ten normal right handed subjects, functional MR images were obtained using a 1.5-T MR scanner and the EPI BOLD technique. An item recognition task was used for stimulation, and during the activation period of the verbal working memory task, consonant letters were used. During the activation period of the visual working memory task, symbols or diagrams were employed instead of letters. For the post-processing of images, the SPM program was used, with the threshold of significance set at p <.001. We assessed activated brain areas during the two stimulation tasks and compared the activated regions between the two tasks. RESULTS: The prefrontal cortex and secondary visual cortex were activated bilaterally by both verbal and visual working memory tasks, and the patterns of activated signals were similar in both tasks. The superior parietal cortex was also activated by both tasks, with lateralization to the left in the verbal task, and bilaterally without lateralization in the visual task. The inferior frontal cortex, inferior parietal cortex and temporal gyrus were activated exclusively by the verbal working memory task, predominantly in the left hemisphere. CONCLUSION: The prefrontal cortex is activated by two stimulation tasks, and this is related to the function of the central executive. The language areas activated by the verbal working memory task may be a function of the phonological loop. Bilateral prefrontal and superior parietal cortices activated by the visual working memory task may be related to the visual maintenance of objects, representing visual working memory.
Adult↗