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J Y Byun

Publications and source records attributed to J Y Byun.

At least 19 recordsLinked to original sources
PubMed2005

Magnetic resonance imaging and diffusion-weighted imaging changes after hypoglycemic coma.

The authors report a case of severe hypoglycemic encephalopathy in an elderly patient. The magnetic resonance images showed bilateral cortical signal changes and basal ganglia lesions, which spared the thalami. The lesions were bright on fluid-attenuated inversion recovery and diffusion-weighted images and dark on the apparent diffusion coefficient map, being more conspicuous on the diffusion-weighted images than on the fluid-attenuated inversion recovery images. A literature review of the imaging features and pathophysiological mechanism in comparison with those of hypoxic ischemic injury is discussed.

Aged↗
PubMed2001

Proliferative actions of natriuretic peptides on neuroblastoma cells. Involvement of guanylyl cyclase and non-guanylyl cyclase pathways.

To identify neural tumor cell lines that could be used as models to study growth-related natriuretic peptide actions, we determined the effects of these peptides on the proliferation of human and rodent neuroblastoma cell lines. Subnanomolar concentrations of atrial natriuretic peptide (ANP) and type C natriuretic peptide (CNP) stimulated proliferation in all four cell lines. These actions were associated with cGMP elevation and were blocked by a protein kinase G inhibitor. These data imply the involvement of guanylyl cyclase (GC)-coupled natriuretic receptors. However, higher concentrations of ANP and CNP, and low concentrations of des-[Gln(18),Ser(19),Gly(20),Leu(21),Gly(22)]-ANP(4-23)-NH(2) (desANP(4-23)) (analog for NPR-C receptor) exerted antiproliferative actions in three of the cell lines. These effects were insensitive to a protein kinase G inhibitor and to HS-142-1, suggesting that growth-inhibitory actions involved a non-GC receptor. They did not appear to involve cAMP, protein kinase A, protein kinase C, or calcium mobilization but were abolished when constitutive mitogen-activated protein kinase activity was inhibited. Radioligand binding experiments revealed the presence of a uniform class of binding sites in NG108 cells and multiple binding sites in Neuro2a cells. Northern and reverse transcriptase-polymerase chain reaction analyses revealed differential gene expression for NPR-A/B/C in NG108 and Neuro2a cells. The results indicate that natriuretic peptides stimulate neuroblastoma cell proliferation through type NPR-A/B (GC) receptors. Higher concentrations of ANP and CNP exerted a mitogen-activated protein kinase-dependent antiproliferative action mediated by a non-GC receptor that interacts with desANP(4-23) with relatively high affinity.

Atrial Natriuretic Factor↗
PubMed2001

Pituitary adenylyl cyclase-activating polypeptide stimulates DNA synthesis but delays maturation of oligodendrocyte progenitors.

The neuropeptide pituitary adenylyl cyclase-activating peptide (PACAP) and one of its receptors (PAC(1)) are expressed in embryonic neural tube, where they appear to regulate neurogenesis and patterning. We now show that PAC(1) gene expression is also present in neonatal rats in the ventricular and subventricular zones and in the optic chiasm, areas that are rich in oligodendrocyte (OL) progenitors (OLP). Because actions of PACAP on OLP have not been reported, we examined the effects of PACAP on the proliferation of purified OLP in culture and on myelinogenesis in cerebellar slices. Northern analyses on total RNA from purified glial cell subtypes revealed an abundant 7 kb hybridizing transcript in OLP, which was confirmed to correspond to the PAC(1) receptor by reverse transcription-PCR. The presence of this receptor was also corroborated by radioligand binding and cAMP assay. In cultured OL, receptor density decreased during maturation but was partially counterbalanced by the appearance of sites that bound both PACAP and the related peptide vasoactive intestinal peptide. PACAP increased DNA synthesis in OLP cultures almost twofold and increased the bromodeoxyuridine-labeling index in O4-positive OLP. PACAP treatment also resulted in decreased sulfate incorporation into sulfatide in cultures of differentiating OL. The PACAP effect on sulfatide synthesis was fully reproduced in a cerebellar explant model. These findings indicate that PACAP may act at two stages during OL development to (1) stimulate proliferation and (2) delay maturation and/or myelinogenesis.

Animals↗
PubMed2001

Characteristic MR findings of cervical pregnancy.

The aim of this study was to define the characteristic MR findings of cervical pregnancy. Twelve patients with cervical pregnancy underwent MRI because of difficulty in the diagnosis by ultrasonography, human chorionic gonadotropin assessment, and other clinical evaluations. The assessment of MRI included size and location of the lesion, margin, MR signal intensity, rim of low-signal intensity, enhancement pattern, appearance of enhancing solid component, parametrial change, endometrial change, pelvic fluid collection, and ovarian change. All cases showed ill-marginated mass with very heterogeneous signal intensity on T2-weighted images, irregular internal high-signal intensities on T1-weighted images, a partial or circumferential rim of low-signal intensity, dense irregular peripheral enhancement and enhancing papillary solid components with accompanying tubular signal voids, and variably increased parametrial vascularities. This heterogeneous hemorrhagic mass with densely enhancing papillary solid components may be the typical MR finding for cervical pregnancy. J. Magn. Reson. Imaging 2001;13:918-922.

Adult↗
PubMed2001

The findings of ruptured hepatocellular carcinoma on helical CT.

To evaluate the helical CT findings of ruptured hepatocellular carcinoma (HCC), 12 patients with ruptured HCC were reviewed with regard to the tumour's location, size and contour protrusion, the appearance of the mass, the enhancement pattern, multiplicity and secondary changes. All ruptured tumours were located at the periphery of the liver and had a protruding contour. The maximum diameter of tumours ranged from 2 cm to 16 cm. Discontinuity of the hepatic surface was seen in 11 cases. In eight cases, CT images during the arterial phase showed a non-enhancing low attenuating lesion with focal discontinuity and peripheral rim enhancement. Seven cases showed separation of tumour content from the peripheral enhancing rim and intraperitoneal rupture of tumour content into the perihepatic space. Because of the similar appearance to an enucleated orbital globe with remaining sclera, this was termed the "enucleation sign". As well as ruptured masses, 10 cases with non-ruptured masses also showed a non-enhancing low attenuating pattern. Seven cases showed a haematoma with high attenuation around the ruptured mass. The peripheral location, protruding contour, discontinuity of the hepatic surface and surrounding haematoma are helpful signs in the diagnosis of ruptured HCC. The "enucleation sign" may be a characteristic finding in ruptured HCC.

Adult↗
PubMed2000

The vascular manifestations of Behçet's disease: angiographic and CT findings.

The purpose was to evaluate angiographic and CT manifestations of vascular Behçet's disease. The medical records of 64 patients with Behçet's disease, treated in our hospital during the last 4 years, were reviewed. 37 patients underwent angiography or CT in the symptomatic regions because of symptoms or clinical signs of vascular involvement by Behçet's disease. 33 (male:female ratio 28:5; mean age 35 years) of the 37 patients demonstrated vascular involvement, which was surgically proven (18 patients) or diagnosed on angiography (15 patients). Angiograms and CT images of these 33 patients were retrospectively analysed for lesion type, location, extent and other characteristic findings of vascular involvement. 12 patients had only venous lesions, 11 had only arterial lesions and 10 had both arterial and venous lesions. The major angiographic findings of vascular Behçet's disease were acute or chronic thrombosis in deep veins of the lower extremities (19 patients), in the inferior vena cava (4 patients) and in the superior vena cava (2 patients), pseudoaneurysms of large or medium sized arteries (11 patients), and occlusions/ stenoses of distal run-off arteries (13 patients). Common CT findings were obliterated deep veins (8 patients) and non-calcified thickened aneurysmal walls (9 patients), with or without contrast enhancement. The combination of these angiographic and CT findings with clinical manifestations are helpful in distinguishing vascular Behçet's disease from other vasculitides.

Acute Disease↗
PubMed2000

Urinary bladder involvement in patients with systemic lupus erythematosus: with review of the literature.

OBJECTIVES: To investigate the etiologies of urinary bladder involvement in patients with systemic lupus erythematosus (SLE), the clinicoradiologic features of gastrointestinal tract manifestations and clinical outcomes in patients with lupus cystitis accompanied by gastrointestinal manifestations. METHODS: We conducted a retrospective chart review on 413 patients with SLE. Patients were selected for review on the basis of lower urinary tract symptoms including urinary frequency, urgency and urinary incontinence. Radiologic studies were analyzed in patients with lupus cystitis. RESULTS: Ten consecutive patients, complicated with lower urinary tract symptoms, were identified. Underlying etiologies were as follows: lupus cystitis in five, neurogenic dysfunction secondary to transverse myelitis in three, cyclophosphamide-induced cystitis in one and tuberculous cystitis in one patient. All patients with lupus cystitis showed gastrointestinal manifestations, such as abdominal pain, nausea, vomiting and/or diarrhea during the periods of cystitis symptoms. In all patients with lupus cystitis, paralytic ileus was demonstrated on plain abdominal X-ray and ascites, bilateral hydroureteronephrosis and thickened bladder wall were identified on abdominal ultrasound or CT. Abdominal CT revealed bowel wall thickening in four of the five patients. The main sites of thickened bowel on abdominal CT were territory supplied by superior mesenteric artery. Two of five patients with lupus cystitis expired during the follow-up period. CONCLUSION: Diverse etiologies may cause lower urinary tract symptoms in patients with SLE. Lupus cystitis is strongly associated with gastrointestinal involvement and abdominal CT can be a useful radiologic tool to investigate the gastrointestinal tract involvement in patients with lupus cystitis.

Adolescent↗
PubMed1999

Diffuse and focal adenomyosis: MR imaging findings.

Adenomyosis is a common gynecologic disorder that affects women during their menstrual life. Preoperative magnetic resonance (MR) images obtained in 45 patients with pathologically proved adenomyosis who underwent hysterectomy were retrospectively reviewed. Diffuse adenomyosis was seen in 30 cases (66.7%) and focal adenomyosis in 15 cases (33.3%). On T2-weighted MR images, diffuse adenomyosis usually manifested as diffuse thickening of the endometrial-myometrial junctional zone (7-37 mm; mean, 16 mm) with homogeneous low signal intensity. T2-weighted MR images were superior to contrast material-enhanced T1-weighted images in the evaluation of junctional zone thickening. High-signal-intensity foci were observed on T2-weighted images only in nine cases and on both T1- and T2-weighted images in three cases. Focal adenomyosis manifested on both T2-weighted and contrast-enhanced T1-weighted MR images as a localized, low-signal-intensity round or oval mass with a diameter of 2-7 cm (mean, 3.8 cm). All but one of the focal lesions had ill-defined margins. High-signal-intensity foci were noted in all cases of focal adenomyosis, either on T2-weighted images only (four cases) or on both T1- and T2-weighted images (11 cases). MR imaging is useful in diagnosing adenomyosis, differentiating adenomyosis from uterine myoma, and planning appropriate treatment.

Adenomyoma↗
PubMed1999

CT features of systemic lupus erythematosus in patients with acute abdominal pain: emphasis on ischemic bowel disease.

PURPOSE: To evaluate the computed tomographic (CT) features of systemic lupus erythematosus (SLE) in patients with acute abdominal pain. Special emphasis was placed on the analysis of ischemic bowel disease. MATERIALS AND METHODS: The authors retrospectively reviewed the images from 39 abdominal CT examinations performed in 33 patients with SLE and acute abdominal pain. Images were evaluated for bowel wall changes, mesenteric changes, fluid collection, retroperitoneal lymphadenopathy, peritoneal enhancement, and hepatomegaly as well as for changes in other abdominal organs. Ischemic bowel disease was diagnosed if at least three of the following signs were seen: bowel wall thickening, target sign, dilatation of intestinal segments, engorgement of mesenteric vessels, and increased attenuation of mesenteric fat. RESULTS: Thirty-one (79%) of the 39 examinations had CT findings diagnostic of ischemic bowel disease, including symmetric bowel wall thickening (n = 29), target sign (n = 26), and mesenteric vascular engorgement and haziness (n = 31). In 24 cases, bowel wall thickening was multifocal, with variable length, and did not appear to be confined to a single vascular territory. CONCLUSION: The most common CT finding in patients with SLE and acute abdominal pain is ischemic bowel disease. CT is useful for detecting the primary cause of gastrointestinal symptoms, planning treatment, and monitoring for infarction or perforation.

Abdomen, Acute↗
PubMed1999

Primary mucinous cystadenocarcinoma of the appendix: CT findings.

OBJECTIVE: The preoperative diagnosis of a primary appendiceal tumor can be difficult because of its rarity and the paucity of material in the radiology literature. The purpose of this study was to describe CT findings in six patients with primary mucinous cystadenocarcinoma of the appendix. CONCLUSION: When CT reveals a cystic mass with enhancing wall nodularity in the expected area of the appendix, especially in older patients, the possibility of primary mucinous cystadenocarcinoma should be considered.

Aged↗
PubMed1999

Two cases of common bile duct stone after liver transplantation.

Biliary complications after orthotopic liver transplants are a continuing cause of morbidity and mortality. Biliary stones and sludge are less well known complications of hepatic transplantation, although they have long been recognized. Recently we experienced two cases of biliary stones developed after liver transplantation. One 32-year-old male, who frequently admitted due to recurrent cholangitis, was treated with percutaneous transhepatic biliary drainage and choledochojejunostomy with cholecystectomy. The other 58-year-old male, who had stones in commone bile duct, was treated by endoscopic manipulation. They are in good condition without recurrent bile duct stones or its accompanying complications. Although stones and sludge are relatively infrequent after liver transplantation, surgical or interventional radiologic treatments are usually performed for treatment.

Adult↗
PubMed1998

Post-traumatic arterial priapism: colour Doppler examination and superselective arterial embolization.

PURPOSE: To evaluate selective embolization for management of post-traumatic priapism and colour Doppler sonography for the diagnosis of the causative lesion and for planning embolization. MATERIALS AND METHODS: Six male patients with post-traumatic priapism underwent selective angiography and embolization. Colour Doppler sonography with grey-scale was performed in all six patients before angiography. RESULTS: Selective angiography showed intracavernosal arteriovenous fistulas in all patients and pseudoaneurysm of the cavernosal artery (or common penile artery) in three patients. After successful embolization, detumescence was achieved in all patients. Colour Doppler sonography enabled localization and characterization of the lesion causing priapism in four patients. Grey-scale ultrasonography showed the dilated cavernosal sinuses in all patients. CONCLUSION: Angiography with selective embolization is safe and effective method to correct post-traumatic priapism. Colour Doppler sonography with grey scale is a useful preangiographic study, as it allows for characterization and localization of the causative lesion except lesions at the proximal cavernosal or distal penile artery near the symphysis pubis.

Adult↗
PubMed1998

Benign solitary fibrous tumour of the pre-sacral space: MRI findings.

Benign solitary fibrous tumour, a rare mesenchymal tumour of adults, usually arises from the pleura. Only a few cases have been reported in the retroperitoneum and, to our knowledge, there has been no report of its imaging features. We describe the MRI features of benign solitary fibrous tumour arising from the pre-sacral space.

Humans↗
PubMed1997

Resistive index of the intrascrotal artery in scrotal inflammatory disease.

PURPOSE: To investigate the utility of the resistive indices (RIs) of the epididymal and intratesticular arteries, and to establish diagnostic criteria for scrotal inflammatory disease on the basis of quantitative color Doppler sonography. MATERIAL AND METHODS: We prospectively examined 29 consecutive patients with scrotal pain, and 15 normal control subjects. The RIs of the intratesticular and epididymal arteries were obtained from color Doppler sonographs. RESULTS: The RIs of the testicular artery in epididymoorchitis were significantly lower than those in normal control subjects and in epididymitis (p < 0.01) while the RIs of the testicular artery in epididymitis and control subjects were similar (p > 0.5). With a cut-off value of RI = 0.5, sensitivity, specificity, accuracy, and positive and negative predictive values were 91%, 94%, 94%, 83%, and 77% respectively. The mean RI of the epididymal arteries in epididymitis and epididymoorchitis was 0.49 +/- 0.11. A high level of diagnostic accuracy in scrotal inflammatory disease was achieved when the RIs of the intratesticular and epididymal arteries were less than 0.5 and 0.7 respectively. CONCLUSION: The RI of the intrascrotal artery would give a more objective evaluation than subjective assessment and could provide diagnostic criteria for scrotal inflammatory disease.

Adolescent↗
PubMed1997

Blunt traumatic rupture of the diaphragm: sonographic diagnosis.

Ultrasonographic features of seven patients with diaphragmatic rupture due to blunt trauma were analyzed. The ruptures occurred at the left hemidiaphragm in four patients and at the right in three. Direct ultrasonographic findings were as follows: disrupted diaphragm in four patients; nonvisualized diaphragm in three patients; floating diaphragm in two patients; and herniation of the liver or bowel loops through the diaphragmatic defect in three patients. Indirect sonographic findings included pleural effusion or subphrenic fluid collection in five patients and splenic laceration in one. Although the number of patients was limited, ultrasonography was very useful for the diagnosis of diaphragmatic rupture.

Adult↗