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Biomedical subjects

J K Han

Publications and source records attributed to J K Han.

At least 109 records · Page 6Linked to original sources
PubMed1992

Reducing inositol lipid hydrolysis, Ins(1,4,5)P3 receptor availability, or Ca2+ gradients lengthens the duration of the cell cycle in Xenopus laevis blastomeres.

We have microinjected a mAb specifically directed to phosphatidylinositol 4,5-bisphosphate (PIP2) into one blastomere of two-cell stage Xenopus laevis embryos. This antibody binds to endogenous PIP2 and reduces its rate of hydrolysis by phospholipase C. Antibody-injected blastomeres undergo partial or complete arrest of the cell cycle whereas the uninjected sister blastomeres divided normally. Since PIP2 hydrolysis normally produces diacylglycerol (DG) and inositol 1,4,5-triphosphate (Ins[1,4,5]P3), we attempted to measure changes in the levels of DG following stimulation of PIP2 hydrolysis in antibody-injected oocytes. The total amount of DG in antibody-injected oocytes was significantly reduced compared to that of water-injected ones following stimulation by either acetylcholine or progesterone indicating that the antibody does indeed suppress PIP2 hydrolysis. We also found that the PIP2 antibodies greatly reduced the amount of intracellular Ca2+ released in the egg cortex during egg activation. As an indirect test for Ins(1,4,5)P3 involvement in the cell cycle we injected heparin which competes with Ins(1,4,5)P3 for binding to its receptor, and thus inhibits Ins(1,4,5)P3-induced Ca2+ release. Microinjection of heparin into one blastomere of the two-cell stage embryo caused partial or complete arrest of the cell cycle depending upon the concentration of heparin injected. We further investigated the effect of reducing any [Ca2+]i gradients by microinjecting dibromo-BAPTA into the blastomere. Dibromo-BAPTA injection completely blocked mitotic cell division when a final concentration of 1.5 mM was used. These results suggest that PIP2 turnover as well as second messenger activity influence cell cycle duration during embryonic cell division in frogs.

Animals↗
PubMed1992

Therapeutic effect of transcatheter oily chemoembolization therapy for encapsulated nodular hepatocellular carcinoma: CT and pathologic findings.

An emulsion of iodized oil and doxorubicin hydrochloride was intraarterially injected in 27 patients with encapsulated single nodular hepatocellular carcinoma (HCC). Computed tomography (CT) was performed 1-3 weeks after injection, and the lesions were resected 1-4 weeks thereafter. The percentages of tumor necrosis were evaluated in cut surfaces of resected specimens and were compared with the findings at iodized-oil CT. Six tumors with complete intratumor retention of iodized oil had 98% necrosis, and 21 tumors with incomplete retention had 64% necrosis. Two tumors with complete retention of iodized oil in the surrounding liver had 100% necrosis, while 16 tumors with partial retention and nine tumors without retention of iodized oil in surrounding liver had 74% and 62% necrosis, respectively. Complete retention of iodized oil in the tumor and surrounding liver demonstrated the best therapeutic effects. Evaluation of the pattern and distribution of iodized oil in the tumor and surrounding liver with iodized-oil CT is useful in the assessment of the therapeutic effects of transcatheter arterial embolization in encapsulated nodular HCCs.

Carcinoma, Hepatocellular↗
PubMed1992

MR imaging of hypertrophic cardiomyopathy.

To assess the capability of magnetic resonance (MR) imaging to define the presence, distribution, and severity of the hypertrophic process, MR imaging was performed in 20 patients with hypertrophic cardiomyopathy and in five healthy volunteers. Among the 20 patients, 13 were classified as having asymmetric septal hypertrophy and seven as having apical hypertrophy. The mean myocardial thickness in the four-chamber view obtained in end diastole in asymmetric septal hypertrophy was 23.5 mm +/- 6.8 (mean +/- standard deviation) in the basal septum; the ratio of septal to posterolateral wall thickness was 2.05 +/- 0.44 (P < .05); those values were 10.4 mm +/- 2.7 and 1.01 +/- 0.19, respectively, in five healthy volunteers. The mean myocardial thickness in apical hypertrophy was 25.3 mm +/- 4.1 in the apex, and the ratio was 2.21 +/- 0.51 (P < .05); these values were 9.6 mm +/- 1.5 and 0.95 +/- 0.17, respectively, in five healthy volunteers. Three different subtypes of hypertrophic cardiomyopathy - resting obstructive (n = 5), latent obstructive (n = 3), and nonobstructive (n = 5) - were classified according to findings at catheterization in the 13 patients with asymmetric septal hypertrophy.

Adult↗
PubMed1992

Percutaneous removal of retained intrahepatic stones with a pre-shaped angulated catheter: review of 96 patients.

Intrahepatic biliary stone disease is prevalent in East Asia and there is a high frequency of retained intrahepatic stones after surgical treatment. Percutaneous removal of retained intrahepatic stones with a pre-shaped angulated catheter and a Dormier basket was attempted in a group of 96 patients who had a T-tube. Seventy-six had multiple intrahepatic stones, confined to one hepatic lobe in 52 patients. Stones were exclusively intrahepatic in 68 cases. Biliary strictures were present in 92 cases (95.8%). A combination of techniques was used including pre-shaped angulated catheters, irrigation suction, balloon dilatation of strictures, crushing of large stones and extracorporeal shockwave lithotripsy. Retained stones were completely removed in 48 cases, and incompletely removed in 22 cases. The overall success rate was 72.9%. There were only minor complications. No mortality or significant morbidity requiring hospitalization occurred. Angular deformity, stricture of bile ducts and impacted stones were the most frequent factors responsible for failure or incomplete removal of retained stones. Fluoroscopically guided percutaneous interventional procedures with a pre-shaped angulated catheter are useful complementary procedures to surgery for patients with intrahepatic stones. The major benefits of an individually angulated catheter are safety and easy access to small peripheral bile ducts.

Adult↗
PubMed1992

Bronchial stenosis due to endobronchial tuberculosis: successful treatment with self-expanding metallic stent.

Endobronchial tuberculosis is present in 10-40% of patients with active pulmonary tuberculosis, and more than 90% of the patients with endobronchial tuberculosis have some degree of bronchial stenosis. The primary treatment for tuberculous bronchial stenosis is antituberculous chemotherapy combined with steroids, but some patients do not respond well, and more aggressive treatment is needed to restore the patency of the involved bronchus. Balloon dilatation of tuberculous bronchial stenosis has been reported to be successful. However, in our experience, balloon dilatation of the stenotic segment has not significantly improved patients' clinical symptoms except in those with very short segmental stenosis. We describe a case of tuberculous bronchial stenosis that was successfully treated with Gianturco self-expanding metallic stents.

Adult↗
PubMed1992

[IL-2 potentiates the IL-3 production by ConA activated mouse splenic T cells].

In addition to the regulation of T cell growth, IL-2 exerts effects on the induction of certain lymphokines. We show here that IL-2 synergizes with 5 micrograms/ml of ConA to promote the production of IL-3 in mouse splenic T cell cultures. IL-3 was measured as CFU-GEMM-inducing activity on mouse bone marrow progenitor cells in the supernatant of the stimulated mouse splenic T cells (TCM). The resting T cells produced no CFU-GEMM-inducing activity, but could be induced to produce low level of CFU-GEMM-inducing activity in the presence of ConA. In vitro exposure to IL-2 markedly increased CFU-GEMM-inducing activity production (nearly up to 8-fold) by the ConA-activated T cells. Optimal stimulation was observed when 80 u/ml IL-2 was used for 48 h incubation. Anti-mouse IL-3 monoclonal antibody inhibited the CFU-GEMM inducing activity of TCM. Moreover, the TCM stimulated the proliferation of IL-3 dependent cell line FDC-P1. We also show that IL-2 and ConA-treated T cells expressed high level of IL-3 mRNA through dot blot analysis. These results confirmed the nature of CFU-GEMM-inducing activity of TCM as IL-3. The capacity of IL-2 to promote the production of IL-3 may represent an important mechanism by which it mediate the communication between the immune and hematopoietic systems.

Animals↗
PubMed1991

MR findings in liver adenomatosis.

Liver adenomatosis is a rare entity in which multiple hepatic adenomas (more than 10) occur in patients with no prior history of oral contraceptives or androgenic steroid use. This report describes findings of this entity on magnetic resonance imaging (MRI) and discusses the differential diagnosis of this disease.

Adenoma↗
PubMed1991

Intraoperative sonography of hepatocellular carcinoma: detection of lesions and validity in surgical resection.

Eighty-six hepatocellular carcinomas (HCCs) in 67 patients were examined by intraoperative sonography. Sensitivity for detecting tumors with intraoperative sonography was compared with sonography, computed tomography (CT), hepatic angiography, and CT after intraarterial injection of iodized poppy-seed oil (Lipiodol-CT). The overall sensitivities were 76% with sonography, 86% with CT, 89% with angiography, 96% with Lipiodol-CT, and 98% with intraoperative sonography. The differences in sensitivity between intraoperative sonography and sonography (p less than 0.01), CT (p less than 0.01), and angiography (p less than 0.05) were significant. In 35 lesions smaller than 2 cm, the sensitivities of Lipiodol-CT and intraoperative sonography were high (91 and 94%, respectively). In operating field, tumors were invisible in 36 (42%) and nonpalpable in 31 of 86 cases (36%). In 35 tumors smaller than 2 cm, invisible tumors were 66% and nonpalpable tumors were 63%. However, 84 of 86 cases (98%) could be localized with intraoperative sonography. These results suggest that intraoperative sonography is the final diagnostic imaging procedure before surgical resection of tumors and in cases of invisible and nonpalpable tumors in the operating field, this procedure is mandatory to improve surgical results.

Carcinoma, Hepatocellular↗
PubMed1991

The effects of inositol trisphosphates and inositol tetrakisphosphate on Ca2+ release and Cl- current pattern in the Xenopus laevis oocyte.

We report that Ins(1,3,4,5)P4 releases calcium from intracellular stores of intact Xenopus laevis oocytes, as indicated by two different techniques, Ca2(+)-sensitive microelectrodes and a fura-2 imaging system. Ins(1,3,4,5)P4 releases only 20% as much Ca2+ as the same amount of Ins(1,4,5)P3. This effect is not due to the conversion of the injected Ins(1,3,4,5)P4 to Ins(1,4,5)P3, which is known to release Ca2+, because the amount of [3H]Ins(1,3,4,5)P4 that is converted to Ins(1,4,5)P3 is extremely small, as determined using HPLC. Examination of the different current patterns induced by Ins(1,4,5)P3 and Ins(1,3,4,5)P4, when injected into voltage-clamped oocytes, provided further evidence that the Ins(1,3,4,5)P4 was not being converted back to Ins(1,4,5)P3. We investigated the effects of four compounds, three inositol trisphosphates (Ins(1,4,5)P3, Ins(2,4,5)P3, and Ins(1,3,4)P3), and Ins(1,3,4,5)P4, on Cl- current conductance in order to examine (1) the possible role of Ins(1,3,4,5)P4 in cell activation and (2) the relationships between intracellular Ca2+ and the activation of Cl- currents. Immature stage VI Xenopus laevis oocytes were voltage-clamped and injected with Ins(1,4,5)P3, Ins(2,4,5)P3, and Ins(1,3,4)P3. Ins(1,4,5)P3 and Ins(2,4,5)P3 triggered Ca2(+)-dependent Cl- currents, but Ins(1,3,4)P3 did not trigger currents nor did it release intracellular Ca2+. Ins(2,4,5)P3 was fourfold less effective at inducing the immediate Cl- current pulse than Ins(1,4,5)P3. The Cl- current pattern was quite dependent on the amount of Ins(1,4,5)P3 injected into the oocyte. Low amounts of Ins(1,4,5)P3 triggered only an immediate single Cl- current pulse, whereas large amounts triggered the immediate single pulse, followed by a quiescent period, followed by oscillating Cl- currents. In contrast to the response of Ins(1,4,5)P3, injection of Ins(1,3,4,5)P4 triggered only oscillating Cl- currents whose magnitude, but not pattern, was dependent on the amount injected into the cell. The currents generated by Ins(1,3,4,5)P4 resemble the oscillating Cl- currents triggered by large amounts of Ins(1,4,5)P3 and Ins(2,4,5)P3. Ins(1,3,4,5)P4, unlike Ins(1,4,5)P3 and Ins(2,4,5)P3, rarely caused an immediate Cl- current pulse, but caused an immediate release of calcium. Therefore, we suggest that the oscillating currents are only indirectly dependent on calcium. These [Ca2+]i and conductance measurements suggest that both Ins(1,4,5)P3 and Ins(1,3,4,5)P4 have roles in intracellular Ca2+ regulation.

Animals↗
PubMed1991

Congenital broncho-oesophageal fistula in the adult.

Five patients with congenital broncho-oesophageal fistula confirmed by fistulectomy are presented. Clinical symptoms were chronic or recurrent pulmonary infection, and three patients experienced coughing after swallowing. Pre-operative oesophagograms demonstrated broncho-oesophageal fistulas in all five patients. The fistulous communications were from the lower oesophagus to segmental bronchi of the lower lobe and to the left main bronchus. The fistulas showed smooth marginated serpentine margins with areas of internal trabeculation, and in two patients the fistulas communicated with anomalous bronchi. One patient had anomalous bronchi and subsequently underwent lobectomy which showed microscopic findings of intralobar sequestration. The oesophagus showed localized tenting with its apex to the fistula and mild ipsilateral displacement in four patients.

Adult↗
PubMed1991

Membranous obstruction of the inferior vena cava with Budd-Chiari syndrome: MR imaging findings.

Membranous obstruction of the inferior vena cava (IVC) is a curable cause of a primary type of Budd-Chiari syndrome. Magnetic resonance (MR) imaging and vena cavography were performed on nine patients with membranous obstruction of the IVC. The MR findings were retrospectively analyzed and compared with computed tomographic findings in seven patients. The morphologic features of membranous obstruction of the IVC on spin-echo MR images were a curvilinear soft-tissue membrane (five cases) or an obliterated lumen of a hepatic segment of the IVC (four cases) in transverse or sagittal views. The lumen below the obstruction revealed flow-related signal (seven cases), intraluminal thrombus (one case), and thrombotic occlusion (one case). The hepatic veins were narrow and disoriented without connection to the hepatic segment of the IVC just below the diaphragm. On T2-weighted images, inhomogeneity with high signal intensity was shown more prominently in the hepatic parenchyma in Simson type II or III membranous obstruction. Other findings were hepatosplenomegaly, enlarged caudate lobe, cirrhotic liver, associated hepatoma, and presence of various collaterals.

Adult↗
PubMed1991

Retained intrahepatic stones: treatment with piezoelectric lithotripsy combined with stone extraction.

Extracorporeal shock wave lithotripsy (ESWL) was performed in 11 patients with oriental cholangiohepatitis and intrahepatic stones associated with segmented strictures of intrahepatic ducts. All patients had previously undergone biliary surgery and basket extraction via a T-tube tract at the time of lithotripsy. The indication for ESWL was failure of, or anticipated difficulty with, basket extraction of the stones via a T-tube tract. A piezoelectric lithotriptor was used in all procedures. The average total number of shock waves administered was 29,756 (range, 10,000-61,395). The average number of treatment sessions was 3.1 (range, 1-6); the number of shock waves used in a single session ranged from 10,000 to 15,000 with a frequency of five shots per second and 30%-50% power. In six patients, the stones were successfully fragmented and completely removed; in three of the others of the stones were fragmented and removed. The overall success rate, including complete (54%) and incomplete (27%) success, was 82%. Difficulty in targeting stones, and severe strictures and deformities of intrahepatic ducts, were the factors responsible for failure. No significant complications were observed.

Bile Ducts, Intrahepatic↗
PubMed1991

[Scavenging of probimane on semiquinone free radical formation by doxorubicin in rat heart].

Probimane, dl-bis (4-morpholin-methyl 3,5-dioxopipweazin-1-yl) propane first synthesized in China, is a dioxopiperazin compound with antineoplastic, antimetastatic and radiopotentiating activities. In order to evaluate the mechanisms of cardiotoxicity protective action of probimane, the free radical induced by doxorubicin were analysed by electron spin resonance (ESR) techniques. Our studies showed that doxorubicin stimulated the formation of semiquinone free radicals in the rat heart homogenate and heart cell mitochondria systems, and probimane inhibited the free radical formation in both systems, with the dose-dependent and time-dependent responses. The inhibitory rates of doxorubicin free radical formation in rat heart homogenate system by probimane 0.6 mmol.L-1 at time of 3, 5, 10, 15, 30, 45 and 60 min were 44.6%, 43.0%, 51.5%, 74.3%, 68.1%, 56.1% and 39.9% respectively. The inhibitory rates of semiquinone free radical formation in mitochondria system by probimane at the concentration of 0.02, 0.06, 0.6, 1.2 and 2.4 mmol.L-1 were 17.07%, 29.87%, 63.95%, 64.62% and 83.64%, respectively. Probimane had no effect on NADH2, but inhibited NADH dehydrogenase activity at higher concentration.

Animals↗
PubMed1990

Inositol 1,4,5-trisphosphate-induced calcium release in the organelle layers of the stratified, intact egg of Xenopus laevis.

Using double-barreled, Ca2(+)-sensitive microelectrodes, we have examined the characteristics of the Ca2+ release by inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) in the various layers of Xenopus laevis eggs in which the organelles had been stratified by centrifugation. Centrifugation of living eggs stratifies the organelles yet retains them in the normal cytoplasmic milieu. The local increase in intracellular free Ca2+ in each layer was directly measured under physiological conditions using theta-tubing, double-barreled, Ca2(+)-sensitive microelectrodes in which one barrel was filled with the Ca2+ sensor and the other was filled with Ins(1,4,5)P3 for microinjection. The two tips of these electrodes were very close to each other (3 microns apart) enabling us to measure the kinetics of both the highly localized intracellular Ca2+ release and its subsequent removal in response to Ins(1,4,5)P3 injection. Upon Ins(1,4,5)P3 injection, the ER-enriched layer exhibited the largest release of Ca2+ in a dosage-dependent manner, whereas the other layers, mitochondria, lipid, and yolk, released 10-fold less Ca2+ in a dosage-independent manner. The removal of released Ca2+ took place within approximately 1 min. The sensitivity to Ins(1,4,5)P3 and the time course of intracellular Ca2+ release in the unstratified (unactivated) egg is nearly identical to that observed in the ER layer of the stratified egg. Our data suggest that the ER is the major organelle of the Ins(1,4,5)P3-sensitive Ca2+ store in the egg of Xenopus laevis.

Animals↗
PubMed1990

Lobar bronchioloalveolar carcinoma: "angiogram sign" on CT scans.

The authors reviewed computed tomographic (CT) scans of 12 patients with lobar bronchioloalveolar carcinoma. Seven patients had consolidation of the entire lobe, and five patients had segmental consolidation. After contrast material was administered intravenously, the consolidated lung typically appeared on the scan as an area of homogeneous low attenuation, within which were enhanced branching pulmonary vessels (the CT angiogram sign). To evaluate the specificity of this sign in the discrimination of bronchioloalveolar carcinoma, CT scans of 26 patients who had lobar consolidation from other diseases were randomly mixed with the CT scans of 11 patients with bronchioloalveolar carcinoma. Two independent observers who were unfamiliar with the cases classified 10 and nine of the 11 patients with bronchioloalveolar carcinoma, respectively, as positive for bronchioloalveolar carcinoma by applying the CT angiogram sign, and classified as negative 25 and 23 of the 26 patients without bronchioloalveolar carcinoma, respectively, for an overall specificity of 92.3%. The angiogram sign appeared on the CT scan because of the low-attenuating consolidation, which was caused by the production of mucin or other fluid and the intact bronchovascular framework within the tumor.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1990

CT manifestations of peritoneal leiomyosarcomatosis.

Peritoneal leiomyosarcomatosis causes multiple discrete tumor nodules in the peritoneum, mesentery, and omentum with or without evidence of a primary site. The CT and pathologic findings in seven patients with this disease were reviewed. All seven patients had CT evidence of multiple, discrete peritoneal masses, and five patients showed a central low-attenuation area. CT grade of malignancy in peritoneal tumors was categorized as low (four patients) and high (three patients) on the basis of the degree of central necrosis of the tumors. The CT results correlated with the histopathologic grade of malignancy, although all tumors were grade 2 or higher histopathologically. Ascites and lymphadenopathy were not present in any of the patients. Liver metastases were identified in five patients with central necrosis of the metastases evident in four. The presence of liver metastases and the degree of central necrosis in the liver metastases did not correlate with the size or histologic grade of the primary tumor. Although uncommon, peritoneal leiomyosarcomatosis should be considered when CT shows multiple, discrete peritoneal masses with central necrosis and liver metastases in the absence of ascites and lymphadenopathy.

Adult↗