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Biomedical subjects

D Choi

Publications and source records attributed to D Choi.

125 records · Page 7Linked to original sources
PubMed1991

Enhanced detection of intracardiac sources of cerebral emboli by transesophageal echocardiography.

We performed transesophageal echocardiography in 50 consecutive hospitalized patients with recent transient ischemic attack or stroke of embolic origin to determine whether transesophageal echocardiography is more sensitive than transthoracic echocardiography in detection of possible intracardiac sources of embolism. Twenty-six of 50 patients with a negative transthoracic echocardiogram for potential source of emboli had a transesophageal echocardiography study that demonstrated at least one intracardiac abnormality. Abnormalities noted by transesophageal echocardiography included five of 50 patients with either a left atrial or left atrial appendage clot, four patients with a patent foramen ovale, and nine patients with spontaneous echocardiographic contrast. In 11 of 50 patients with no other source of embolism, we found highly mobile filamentous strands on the mitral valve, which have not been described previously. These mitral valve echo strands may represent a fissured surface or fibrosis that can serve as a nidus for thrombus formation. We detected no unexpected left ventricular thrombus or left atrial myxoma. Factors significantly associated with a greater likelihood of a positive transesophageal echocardiography study included left atrial enlargement, atrial fibrillation, and a calcified or thickened mitral valve. Our study suggests that transesophageal echocardiography is a valuable addition to transthoracic echocardiography in investigating potential intracardiac sources of embolism.

Cerebral Infarction↗
PubMed1987

Sequence analysis of the EF-1 alpha gene family of Mucor racemosus.

Our previous studies have shown that Mucor racemosus possesses three genes (TEF-1, -2 and -3) for EF-1 alpha, and that all three genes are transcribed. However, the level of transcription varies markedly between the three genes, with TEF-1 mRNA levels being approximately two fold higher than TEF-3 and 6 fold higher than TEF-2. We have now completed the DNA sequence of both strands of all three genes and have found that these genes are highly homologous. TEF-2 and TEF-3 are more similar to each other than they are to TEF-1. The TEF-2 and the TEF-3 coding regions differ from TEF-1 at 30 and 37 positions respectively out of 1374 nucleotides. Twenty-six of these nucleotide substitutions were common to both TEF-2 and TEF-3, and the majority of the substitutions were clustered in the 5' region of the coding sequences. While the majority of these changes were silent, TEF-2 and TEF-3 differed from TEF-1 by having a lysine instead of a glutamate at amino acid position 41. In addition, TEF-2 and -3, but not TEF-1, each have an intron located near the 5' end of the coding region, although its size and sequence is not conserved between the two genes. All three genes have a conserved intron near the 3' end of the coding region. The sequence data have been analyzed with respect to the structure and function of EF-1 alpha in protein biosynthesis.

Amino Acid Sequence↗
PubMed1983

Medial thalamic hemorrhage with amnesia.

Three patients had amnesia and confusion as presenting features of thalamic hemorrhage. They had a relatively benign clinical appearance and lacked characteristics of the syndrome usually associated with thalamic hemorrhage. We reviewed hypotheses regarding a mechanism for the amnesic syndrome and concluded that lesions involving the medial thalamic nucleus were responsible for the amnesia observed.

Aged↗
PubMedDate not supplied

Proximal gastrectomy and jejunal pouch interposition: radiographic evaluation of postoperative findings.

BACKGROUND: We assessed the postoperative findings of proximal gastrectomy and jejunal pouch interposition with contrast radiography. METHODS: Eleven patients with proximal gastrectomy and jejunal pouch interposition for proximal gastric carcinoma underwent contrast radiography. We evaluated the radiographic findings of the remnant stomach and interposed jejunal pouch. RESULTS: The interposed jejunal pouch showed good expansion, and the motility of the remnant gastric antrum was normal in all patients. One patient had significant lumenal narrowing of the esophageal pouch anastomotic site. Leak at the anastomotic site was not found. Reflux into the esophagus from the pouch was observed in two patients. Gastric emptying time was considerably delayed in two patients. CONCLUSION: Follow-up upper gastrointestinal series of the proximal gastrectomy and jejunal pouch interposition showed different postoperative findings. Awareness of the normal and abnormal findings is essential in the accurate postoperative evaluation of these patients.

Adult↗
PubMedDate not supplied

Arteriovenous malformation of the pancreas in a patient with gastrointestinal bleeding: helical CT findings.

Dynamic computed tomographic (CT) findings of arteriovenous malformation (AVM) of the pancreas include strong enhancement or conglomeration of small hypervascular spots in the pancreas and early contrast filling of the portal vein during the arterial phase. We describe a case with pancreatic AVM in which we identified enlarged arterial feeders and draining veins as supportive findings of the diagnosis and ulceration into the pancreatic duct as a possible cause of gastrointestinal bleeding at contrast-enhanced CT.

Arteriovenous Malformations↗
PubMedDate not supplied

Multiple infarcted regenerative nodules in liver cirrhosis after systemic hypotension due to septic shock: radiologic findings.

We describe a case of multiple infarcted regenerative nodules in a patient with advanced liver cirrhosis who had experienced an episode of septic shock. Sonography showed multiple hypoechoic or isoechoic nodules; contrast-enhanced computed tomography showed multiple, low-attenuating nodules with rim enhancement; and magnetic resonance imaging showed multiple nodules of low, iso-, or high signal intensity. Explanted liver showed coagulation necrosis of multiple regenerative nodules. Peribiliary cysts in chronic liver diseases, liver abscesses, spontaneous necrosis of hepatocellular carcinomas, and metastasis should be differentiated.

Adult↗
PubMedDate not supplied

Pulmonary tuberculosis presenting as acute respiratory failure: radiologic findings.

PURPOSE: The purpose of this work was to describe the radiologic findings of pulmonary tuberculosis in patients who presented with acute respiratory failure. METHODS: We included patients who had newly diagnosed active pulmonary tuberculosis and who presented with acute respiratory failure. Initial chest radiographic (n = 17) and high-resolution CT (n = 11) findings of each patient were analyzed retrospectively. RESULTS: Of 1,010 patients with active pulmonary tuberculosis, 17 patients (1.7%) presented with acute respiratory failure. Nine (53%) of the 17 patients died. The most common initial chest radiographic findings were small nodular lesions (16/17; 94%), consolidation (13/17; 76%), and ground-glass opacity (12/17; 70%). Eleven (69%) of 16 nodular lesions, 9 of 13 (69%) consolidations, and 10 of 12 (83%) ground-glass opacities were bilateral. On HRCT (n = 11), miliary micronodular lesions were seen in 6 patients (55%), whereas bronchogenic spread of tuberculosis with disseminated centrilobular nodules and tree-in-bud appearance was seen in 5 patients (45%). Diffuse areas of ground-glass attenuation were seen in all six patients with miliary nodules and four of five patients with bronchogenic spread of tuberculosis. CONCLUSION: Patients with pulmonary tuberculosis occasionally present with acute respiratory failure. In this condition, chest radiograph most commonly shows bilateral small nodular lesions mixed with consolidation or ground-glass opacity, whereas HRCT demonstrates findings of miliary or bronchogenic disseminated tuberculosis with diffuse areas of ground-glass attenuation.

Acute Disease↗
PubMedDate not supplied

Intestinal metastases from gastric adenocarcinoma: helical CT findings.

PURPOSE: The purpose of this work was to describe the helical CT findings of intestinal metastasis from gastric adenocarcinoma. METHOD: Twenty-three patients with intestinal metastasis from gastric adenocarcinoma found at helical CT were included. CT findings and clinical and pathologic data were reviewed. RESULTS: The most common characteristic finding was target-like concentric bowel wall thickening (thick inner high-outer low, n = 18) involving multiple long segments with progressive thickening of the enhancing inner layer. Fifteen cases (65%) involved multiple sites, and the ascending colon (n = 12) and rectum (n = 11) were the two most common sites. Peritoneal carcinomatosis (n = 15, 65%) and bowel obstruction (n = 14, 61%) were common associated findings. Regarding the primary lesion, the majority was linitis plastica (n = 16) and poorly differentiated adenocarcinoma with or without signet-ring cell differentiation (n = 14). CONCLUSION: Intestinal metastasis from gastric adenocarcinoma, especially of the linitis plastica type, most commonly showed target-like long segmental wall thickening with a characteristically thick inner enhancing layer on helical CT.

Adenocarcinoma↗
PubMedDate not supplied

Opacification of the intrahepatic portal veins during CT hepatic arteriography.

PURPOSE: The purpose of this study was to ascertain the cause of opacification of the portal veins during CT hepatic arteriography (CTHA). METHOD: A total of 155 consecutive patients with hepatocellular carcinoma were evaluated with CTHA as preoperative staging. The opacification of the portal veins during CTHA was categorized as opacification of the main portal vein, right or left branches of the main portal vein (generalized), and segmental or subsegmental portal veins (localized). Hepatic angiography was compared and possible causes were evaluated. RESULTS: One hundred eight (70%) of 155 patients showed intrahepatic portal vein opacification at CTHA: generalized in 60 patients (39%) and localized in 48 patients (31%). Intrahepatic causes were arterioportal shunts due to hepatocellular carcinoma in 20 (19% of 108 patients), previous liver biopsy in 9 (8%), and portal vein thrombosis in 4 (4%). Extrahepatic cause was counted in 57 cases (53%) and was due to inflow of contrast material via nonmesenteric portal circulation through the gastric antrum, duodenum, and/or pancreas. CONCLUSION: Intrahepatic portal veins are frequently opacified during CTHA, and the causes were arterioportal shunts through hepatocellular carcinoma, postbiopsy shunt, portal vein thrombosis, and inflow of contrast material via the nonmesenteric portal circulation.

Adult↗
PubMedDate not supplied

Detection of hepatocellular carcinoma: combined T2-weighted and dynamic gadolinium-enhanced MRI versus combined CT during arterial portography and CT hepatic arteriography.

PURPOSE: The purpose of this study was to compare the preoperative detectability of hepatocellular carcinomas (HCCs) using combined T2-weighted and dynamic gadolinium-enhanced MRI and combined CT during arterial portography (CTAP) and CT hepatic arteriography (CTHA). METHOD: Thirty-three patients with 43 HCCs underwent T2-weighted and dynamic gadolinium-enhanced MRI and combined CTAP and CTHA. The diagnosis was established by pathologic examination following surgical resection in 26 patients and by biopsy in 7 patients. The MR protocol included fast SE with two TEs (including T2-weighted imaging) and precontrast and gadolinium-enhanced T1-weighted fast multiplanar spoiled gradient-recalled echo images with dynamic study. The MR images of all sequences and the paired CTAP and CTHA images were independently reviewed by three radiologists. Image review was conducted on a segment-by-segment basis. Diagnostic accuracy was evaluated with receiver operating characteristic analysis. RESULTS: The accuracies (Az values) of MRI of all sequences and combined CTAP and CTHA for all observers were 0.960 and 0.959, respectively. The mean sensitivities of MRI and CT were 90 and 94%, respectively. The differences were not statistically significant. The mean specificity of MRI (99%) was significantly higher than that of combined CTAP and CTHA (92%). CONCLUSION: Combined T2-weighted and dynamic gadolinium-enhanced MRI is as accurate as combined CTAP and CTHA for preoperative detection of HCCs.

Adult↗
PubMedDate not supplied

17Beta-estradiol inhibits proliferation of cultured vascular smooth muscle cells induced by lysophosphatidylcholine via a nongenomic antioxidant mechanism.

OBJECTIVE: Lysophosphatidylcholine (lysoPC), an active component of oxidized low-density lipoprotein, stimulates proliferation of vascular smooth muscle cells (VSMC). We investigated the direct impact of 17beta-estradiol (E2) on the proliferation of VSMC from rat aorta. RESULTS: VSMC derived from both female and male rats expressed estrogen receptors alpha and beta. Treatments with 1% fetal bovine serum or 5 microM lysoPC increased the incorporation of [3H]-thymidine in VSMC obtained from female rats. 17Beta-E2 did not alter the response to fetal bovine serum, but significantly suppressed the enhanced deoxyribonucleic acid synthesis which had been induced by lysoPC in a dose-dependent manner (10(-4)-10(-6) M). Estrogen also inhibited the proliferation of VSMC from male animals. ICI 182,780, a specific estrogen receptor antagonist, and 17alpha-E2, an inactive form of estradiol, also decreased the mitogenic response to lysoPC in VSMC. In addition, N-acetyl-L-cysteine, a potent antioxidant, inhibited the lysoPC effect. Flow cytometric analysis using the oxidation-sensitive probe 2',7'-dichlorofluorescin diacetate revealed that elevated intracellular formation of reactive oxygen species elicited with lysoPC was depressed significantly by 17beta-E2, ICI 182,780, or 17alpha-E2 as well as by N-acetyl-L-cysteine. CONCLUSION: 17Beta-E2 inhibits in vitro VSMC proliferation induced by lysoPC via a nongenomic antioxidant mechanism.

Animals↗
PubMedDate not supplied

Characterization and hormonal regulation of granulosa cell-derived insulin-like growth factor binding protein-4.

OBJECTIVE: Because of the potential importance of insulin-like growth factor binding protein-4 (IGFBP-4) to ovarian physiology and the obvious limitations imposed by in vivo-exclusive experimental paradigms, we set out to delineate the characteristics and hormonal regulation of granulosa cell-derived IGFBP-4 under in vitro circumstances. METHODS: Granulosa cells obtained by follicular puncture of the ovaries from diethylstilbestrol-primed intact immature rats were subjected to culture for up to 72 hours. Insulin-like growth factor binding protein-4 mRNA extracted from culture was subjected to Northern blot hybridization. Data normalization was assured by reprobing with the hamster Chinese hamster ovary B (CHOB) cDNA, and the IGFBP-4/CHOB ratio was calculated. Conditioned culture media were subjected to Western ligand blot before and after immunoprecipitation with a rat IGFBP-4-directed polyclonal antiserum (alpha-B104). RESULTS: Immunoprecipitation studies revealed granulosa cell-derived IGFBP-4 to be composed of a major 24-kDa species as well as a relatively minor 27-kDa moiety. Given cultures of untreated granulosa cells from immature estrogen-treated rats, transcripts corresponding to IGFBP-4 displayed an initial temporary decline culminating in a 6-hour nadir (a decrease of 67%; P < .05) followed by relatively prompt recovery (within 24 hours) to levels comparable to those noted at the outset of the culture (time 0). However, additional (albeit statistically insignificant) increments were noted at the 48-hour (but not 72-hour) time point. Treatment of granulosa cells with increasing concentration of FSH resulted in decrements of up to 30% (P < .05) in the steady-state levels of IGFBP-4 transcripts. A modest, biphasic, time-dependent response was noted for IGFBP-4 transcripts after treatment with high-dose FSH (100 ng/mL), an effect characterized by 24- and 48-hour increments (51% [P < .05] and 26% [P = .052] over untrated controls, respectively) and a 72-hour decrement (25%; P = .16). The concurrent provision of the C19 aromatase substrate androstenedione (10(-7) mol/L) to the culture medium from 72 hours enhanced the inhibitory effect of FSH (100 ng/mL) for a maximal decrement in IGFBP-4 transcripts of 49% (P < .05). Treatment with insulin-like growth factor (IGF)-I produced limited inhibition (up to 26%) of the steady-state levels of IGFBP-4 transcripts (P < .05). CONCLUSION: Findings indicate the existence of heterogeneously-sized IGFBP-4 species, of which the 27-kDa (as distinct from the 24-kDa) IGFBP-4 moiety constitutes a relatively minor component. The steady-state levels of granulosa cell-derived IGFBP-4 transcripts display relatively limited regulation in response to treatment with either FSH or IGF-I.

Animals↗
PubMedDate not supplied

In vivo hormonal regulation of insulin-like growth factor binding protein-5 mRNA in the immature rat ovary.

OBJECTIVE: Despite the potential importance of insulin-like growth factor binding protein-5 (IGFBP-5) to follicular development, the hormonal regulation of this antigonadotropic IGFBP has not been investigated. Therefore, it was the objective of this study to eludicate the role of gonadotropins and estrogen in the in vivo regulation of IGFBP-5 mRNA expression. METHODS: Two models of follicular development in immature rats were used. Specifically, rats were hypophysectomized and treated with FSH and/or diethylstilbestrol (DES). Alternatively, terminal follicular development was induced in intact immature rats by pregnant mare serum gonadotropin (PMSG) and hCG. The IGFBP-5 mRNA in whole ovarian RNA was assayed by Northern blot hybridization. Localization of expression in PMSG and hCG-stimulated ovaries was further assessed by in situ hybridization. RESULTS: Expression of IGFBP-5 mRNA was increased in ovaries from hypophysectomized rats. Treatment with FSH and/or DES did not alter the abundance of this mRNA. Treatment with PMSG induced a transient increase in IGFBP-5 expression that was localized in a subset of alpha-inhibin-negative follicles. At later times after PMSG, IGFBP-5 expression persisted in the surface epithelium but was not detected in large preovulatory follicles. In vitro studies affirmed the antigonadotropic action of IGFBP-5. CONCLUSION: In vivo expression of IGFBP-5 in the rat ovary is moderated by hormonal treatment both in terms of total expression and follicular localization.

Animals↗