Search PubMed⌕ Search

Biomedical subjects

D I Kim

Publications and source records attributed to D I Kim.

At least 37 records · Page 2Linked to original sources
PubMed2001

The comparative selection between spiral wound and disc tube membranes to treat steel industry wastewater.

To select the most suitable membrane process to treat the final effluent discharged from the S wastewater treatment facility at P Steel Works, the effluent was passed through two types of membrane (spiral wound and disc tube) in a pilot-scale study. The permeate flux and regeneration of each membrane were comparatively observed and the removal efficiency of contaminants determined. The experimental results from employing the disc tube membrane revealed that the fouling was comparably limited by operating the plant at 34 bar recovery and was highly sustained at permeate flux of 75% which equals to 32.9 l/hr.m2. In contrast, the fouling was significantly greater when applying the spiral would membrane with the recovery correspondingly diminished at 72%. The disc-tube membrane was chosen to treat the effluent to be recycled for process water as the water quality satisfied the industry water standards.

Equipment Design↗
PubMed2001

Radionuclide cisternography in spontaneous intracranial hypotension with simultaneous leaks at the cervicothoracic and lumbar levels.

This case report clearly illustrates defined simultaneous cerebrospinal fluid leaks at the cervicothoracic and upper lumbar areas. A 53-year-old woman without a remarkable medical history was hospitalized for sudden onset of severe headache. The headache lasted more than 1 week and standing or sitting positions exaggerated the symptoms, although it was relieved when the patient was recumbent. Radionuclide cisternography was performed using 150 MBq (4 mCi) Tc-99m DTPA. It revealed two cerebrospinal fluid leaks from the cervicothoracic junction bilaterally and the left side of the upper lumbar area. Epidural blood patching was tried at the lumbar level (L1-L2) and showed only a transient effect. A second trial of this method at the level of C7-T1 performed 2 days later resulted in immediate improvement of the symptoms without recurrence. The simultaneous cerebrospinal fluid leaks were detected successfully with radionuclide cisternography using Tc-99m DTPA, which provided a useful guideline for treatment despite the limitations of delayed scanning.

Blood Patch, Epidural↗
PubMed2001

Attenuation of EGF signaling in senescent cells by caveolin.

One of the characteristics of senescent cells is unresponsiveness to external stimuli like EGF. Although they have a normal level of receptors and downstream signaling molecules, EGF cannot induce the activation of Erk kinases and DNA synthesis in senescent cells as much as in young cells. Caveolin proteins directly interact with signaling molecules including EGF receptor and suppress the activation of EGFR upon EGF stimulation. We found that Erk activation after EGF stimulation in senescent human diploid fibroblasts was down-regulated. Those senescent cells showed an increased level of three isoforms of caveolin proteins. This change seems to lie in transcriptional control in senescent cells. We also demonstrated up-regulated caveolin proteins were co-localized with EGFR proteins in detergent-insoluble fractions. From these results, we suggest that the up-regulated expression of caveolin might explain the unresponsiveness of senescent fibroblasts to EGF stimulation.

Animals↗
PubMed2001

Yonsei Stroke Registry. Analysis of 1,000 patients with acute cerebral infarctions.

BACKGROUND AND PURPOSE: The hospital-based stroke registry is a well-established method useful for understanding diverse clinical characteristics of stroke related to geographical, racial or environmental differences. We analyzed the data from 1,000 patients with acute cerebral infarctions registered with the Yonsei Stroke Registry (YSR) which is the first prospective hospital-based observational study in Korea. METHODS: All patients had cerebral infarctions and presented within 7 days of onset. CT or MRI was performed in all patients and a vascular imaging study (digital subtraction or magnetic resonance angiography) was conducted in 53.9% of the patients. Subtype classification was made through a consensus approach based on the strict application of TOAST criteria. RESULTS: The mean age of patients was 62 +/- 12 years, and 60.8% were males. Undetermined cause (UD) was the most frequent subtype (40.6%), which was followed by lacunar stroke (LS 21.5%), cardiac embolism (CE 18.3%), large-artery atherosclerosis (LAA 16.5%) and other determined causes (3.1%). Hypertension was found in 64.3%, smoking in 35.2%, diabetes mellitus in 26.9%, hypercholesterolemia in 24.1%, high hematocrit (> or = 50%) in 21.8%, clinically identified potential cardiac sources of embolism in 18.3%, a history of previous stroke in 22.0% and a history of previous transient ischemic attack in 4.7%. Recurrent stroke was associated with a higher number of risk factors (p < 0.001) and a higher incidence of LAA (p = 0.003) than the first stroke. Vertebrobasilar artery territorial infarction was found in 39.8%, which was associated with higher incidences of LAA and LS and a lower incidence of CE than carotid artery territorial lesions (p = 0.001). The 30-day mortality rate was 5.3% and cerebral herniation caused early death in 52%. CONCLUSION: The distribution of stroke subtypes in the YSR was largely comparable with that of western registries. The highest incidence of UD might be related to the strict application of TOAST criteria.

Aged↗
PubMed2001

Diffusion-weighted image and MR spectroscopic analysis of a case of MELAS with repeated attacks.

We report the clinical and MR manifestations of an 18 year-old girl with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome. Recurrent status epilepticus caused reversible cytotoxic edema on diffusion-weighted images (DWI). Initial and one month follow-up MR spectroscopy, after seizure control, showed some discrepancies in the ratio of metabolites. N-acetylaspartate (NAA) partially recovered (NAA/creatine (Cr) ratio: 1.27-->1.84). This was because of a normalization of decreased NAA due to cellular dysfunction as a result of status epilepticus. A low ratio of NAA/Cr due to abnormal mitochondria remained in the decreased state. Reversible NAA/Cr ratios in the acute lesion suggested that NAA reflects the neuronal function as well as the level of neuronal structural damage. The altered NAA/Cr ratio better correlated with the abnormal signal intensity area of T2-weighted images (T2WI) and DWI than the lactate (Lac)/Cr ratio. With conservative treatment with anti-epileptics not accompanied by coenzyme Q or sodium dichloroacetate, lactate persistently increased (Lac/Cr ratio: 1.01-->1.21) because of the continued production of lactate in cells with respiratory deficiency, which is the main pathology of MELAS.

Adolescent↗
PubMed2001

Moyamoya disease initially presenting visual field defect.

Progressive narrowing of distal carotid arteries and the development of compensatory fine networks are the characteristic findings of moyamoya disease. Cerebral infarction in moyamoya disease is due to a decreased blood flow and shows an uneven distribution in the distal bed of the anterior and middle cerebral arteries. The progression of disease in the posterior circulation follows that in the anterior circulation. Posterior circulation symptoms due to cerebral infarction usually occur in the advanced stage of the disease and follow the anterior circulation symptoms. We encountered an unusual case of moyamoya disease which initially presented with a transient visual field defect. One month later our patient developed blindness and her cerebral angiography showed advanced moyamoya disease.

Adult↗
PubMed2000

Up-regulation of caveolin attenuates epidermal growth factor signaling in senescent cells.

Senescent human diploid fibroblasts do not respond to growth factors like epidermal growth factor (EGF), although they have a normal level of receptors and downstream signaling molecules. To examine the mechanism of signaling attenuation, we investigated Erk activation after EGF stimulation in senescent cells. Senescent cells did not phosphorylate Erk-1/2 after EGF stimulation, whereas young cells did. In those senescent cells, we found an increased level of caveolin proteins and strong interactions between caveolin-1 and EGF receptor. Electron microscopic analysis demonstrated an increased number of caveolae structures in senescent cells. More interestingly, brain, spleen, and lung from 26-month-old rats showed substantial increases of caveolin proteins. However, in the case of p53-induced senescence, caveolin-1 was not induced, and EGF stimulation phosphorylated Erk-1/2 as much as young control cells. Finally, we overexpressed caveolin-1 in young human diploid fibroblasts in which the activation of Erk-1/2 upon EGF stimulation was significantly suppressed. These results suggest that the unresponsiveness of senescent fibroblasts to EGF stimulation may be due to the overexpression of caveolins, which seems to be independent of growth arrest and other aging phenotypes.

Animals↗
PubMed2000

The relationship between the angiographic findings and the clinical features of carotid artery plaque.

The purpose of this study was to investigate the histological characteristics of atheromatous carotid plaque, and to analyze the relationship between the angiographic findings and the clinical features. We retrospectively reviewed 55 cases of carotid endarterectomy for extracranial internal carotid artery stenosis, who were treated at our institute from January 1995 to December 1997. The histological examination included hematoxylin-eosin staining, Masson-trichrome staining, and immunostaining for antismooth muscle antibody and anti-CD68 antibody. The main compositions of the carotid plaque included synthetic type vascular smooth muscle cells and extracellular matrix. The histological findings showed ulceration in 49 (89.1%) cases, calcium deposits in 42 (76.4%) cases, and an inflammatory reaction in 44 (80.0%) cases. Neurological abnormalities were strongly associated with plaque ulceration (P = 0.045) and an inflammatory reaction (P = 0.013), whereas no correlation existed regarding calcium deposits (P = 0.173). The angiographic findings showed ulceration in 46 (83.6%) cases. Plaque ulceration in the angiography findings showed no statistically significant correlation with the histologic findings (P = 0.410) and preoperative neurologic abnormalities (P = 0.059). All of the atherosclerotic risk factors such as hypertension, smoking, diabetes mellitus, hyperlipidemia, and myocardial infarction had no statistically significant correlation with the histological features of the carotid plaque. In conclusion, the main compositions of carotid plaque were synthetic-type vascular smooth muscle cells and extracellular matrix. The histological ulceration and inflammatory reaction of the plaque showed a statistically significant correlation with the preoperative neurologic symptoms, whereas no correlation was seen in the calcium deposits. Angiographic ulceration showed no correlation with the histological findings or preoperative neurologic abnormalities. In addition, the histological findings showed no correlation with the atherosclerotic risk factors.

Aged↗
PubMed2000

Perirolandic hypoperfusion on single-photon emission computed tomography in term infants with perinatal asphyxia: comparison with MRI and clinical findings.

We describe the findings on single-photon emission computed tomography (SPECT) in patients with perinatal asphyxia at term, with perirolandic cortico-subcortical changes on MRI, and to correlate them with clinical features. SPECT of 7 patients was obtained after injection of 185-370 MBq of Tc-99m-ECD (ethyl cysteinate dimer). The patients had spastic quadriplegia (7/7) with perinatal asphyxia (6/7) at term (7/7). The results were correlated with the MRI findings. Hypoperfusion of the perirolandic cortex was clearly seen on SPECT in all patients, even in two with subtle changes on MRI. SPECT demonstrated a more extensive area of involvement than MRI, notably in the cerebellum (in 4), the thalamus (in 7) and basal ganglia (in 5), where MRI failed to show any abnormalities.

Asphyxia Neonatorum↗
PubMed2000

Microvascular decompression of the facial nerve for the treatment of hemifacial spasm: preoperative magnetic resonance imaging related to clinical outcomes.

BACKGROUND: The objective of this study was to investigate the role of preoperative three dimensional short-range magnetic resonance angiography (3D-TOF MRA) in predicting the clinical outcomes following microvascular decompression for the treatment of hemifacial spasm. METHOD: Preoperative magnetic resonance (MR) imaging was performed on all patients with hemifacial spasm (564 cases) between January 1992 and September 1998. Of the 564 patients, 440 patients were included in this retrospective study. The presence of vascular contact, offenders, and anomalies in the vertebro-basilar system, were determined by 3D-TOF MRA prior to microvascular decompression of the facial nerve. The preoperative findings were compared with the surgical findings and clinical outcomes. Findings. A correlation was found between the clinical outcome (p < 0.01) and the presence of a vascular indentation at the root entry zone (REZ) of the facial nerve. A shift of the vertebrobasilar system to the symptomatic side was found in 214 (48.6%) patients with hemifacial spasm, compared to only 10 (13.5%) patients in the control group (p < 0.01). The unilateral vertebral artery was observed in 43 (9.8%) patients with hemifacial spasm and in 8 (10.8%) of the control patients. A hypoplasia of the artery was found in 8 (1.8%) patients with hemifacial spasm and in 1 (1.4%) control patient. The compressing offenders in the patients, discovered by MRI in conjunction with MRA, were as follows: 45.9% (202 patients) in the anterior inferior cerebellar artery (AICA), 34.8% (153 patients) in the posterior inferior cerebellar artery (PICA), 12.5% (55 patients) in the vertebral artery (VA) and 6.8% (30 patients) in multiple vessels. In contrast to the compressing offenders seen on the MRA, the offenders confirmed during surgery were as follows: 43% (189 patients) in the AICA, 36.4% (160 patients) in the PICA, 1.4% (6 patients) in the VA, 19% (84 patients) in multiple vessels, and 0.2% (1 patient) in the vein. In our long-term follow-up series of the 440 patients with hemifacial spasm, an excellent surgical outcome was obtained in 86.3% of cases and a good outcome was achieved in 6.4% (mean follow-up duration, 45.5 months). INTERPRETATION: Preoperative 3D-TOF MRA can identify the relationship between the facial nerve and adjacent vessels in patients with a hemifacial spasm and assist in preoperative planning. This study suggests that 3D-TOF MRA is useful for selecting appropriate patients for surgical treatment and, to some extent, as an additional role for predicting the clinical outcome.

Adult↗
PubMed2000

Senescence-like changes induced by hydroxyurea in human diploid fibroblasts.

Hydroxyurea was found to inhibit the growth of human diploid fibroblasts, which resulted in senescence-like changes both in morphology and replicative potential similar to the replicative senescence. SA-beta-gal activity, a typical characteristic of the replicative senescence was also induced through a long-term treatment of the presenescent cells with 400-800 microgM of hydroxyurea for about 3 weeks. In addition, we determined the levels of cyclin-dependent kinase inhibitors, p21(Waf1) and p16(INK4a), and the p53 tumor suppressor in order to monitor its effect on cell cycle and stress responses. We observed a great induction of both p53 and p21(Waf1), but not of p16(INK4a) in the premature senescent cells. UV-irradiation of the premature senescent cells showed a decreased level of DNA fragmentation presumably ascribed to the reduced activation of stress-activated protein kinases. These results suggest that a chronic hydroxyurea treatment induces the cellular senescence in association with the induction of p53 and p21(Waf1).

Cells, Cultured↗
PubMed2000

Steroidal derived acids as inhibitors of human Cdc25A protein phosphatase.

A group of steroidal derived acids were synthesized and found to be human Cdc25A inhibitors. Their potency ranged from 1.1 to > 100 microM; the best ones compare very favorably with that of the novel cyano-containing 5,6-seco-cholesteryl acid 1 (IC50=2.2microM) reported by us recently (Peng, H.; Zalkow, L. H.; Abraham, R. T.; Powis, G. J. Med. Chem. 1998, 41, 4677). Structure-activity relationships of these compounds revealed that a hydrophobic cholesteryl side chain and a free carboxyl group are crucial for activity. The distance between these two pharmacophores is also important for the potency of these compounds. Several of the compounds showed selective growth inhibition effects in the NCI in vitro cancer cell line panel.

Acids↗
PubMed2000

Emergency surgical recanalisation of A1 segment occluded by a Guglielmi detachable coil.

We describe a case of A1 segment occlusion caused by a tangled Guglielmi detachable coil (GDC) during an endovascular treatment for a ruptured anterior communicating aneurysm. Immediate surgical recanalisation of the occluded artery and clipping of the aneurysm rescued the patient. This case demonstrates that an emergency surgical team, as well as an operating room, should be available during any complicated intra-aneurysmal procedure, so that timely surgical intervention could be carried out without delay.

Cerebral Angiography↗
PubMed2000

Selection of treatment modalities for cerebral arteriovenous malformations: a retrospective analysis of 348 consecutive cases.

The objective was to establish the selection criteria for the optimal management modalities for cerebral arteriovenous malformations. We analysed the complications and late outcomes in 348 consecutive cases (132 microsurgical resections, 202 stereotactic radiosurgeries, 8 embolisations only, 6 combined treatments) managed at Yonsei University Hospital from 1988 to 1997. Files for all patients were analysed. The outcome was classified into good for the patients who returned to their previous job with or without neurological deficits, fair for the patients who were unable to return to work but performed daily activities independently with minor deficits, and poor for the patients who were performing dependent daily activities with major deficits. The outcome of microsurgery was considered good in 108 patients (81.8%), fair in 18 (13.6%), poor in 4 (3.1%), and 2 (1.5%) patients died. Initial insults and haemodynamic complications were the major cause of an unfavourable outcome. The cumulative occlusion rate of the nidus after radiosurgery was 10.2% within 12 months, 75.3% within 24 months, and 89.8% within 36 months. Perilesional imaging changes with neurological deficits (4 permanent and 6 transient, 4.8%) and haemorrhage (16 patients, 7.7%) during the latent interval were the major cause of an unfavourable outcome (1 poor, 4 dead after radiosurgery). Postradiosurgery bleeding occurred frequently within 6 months (6 patients), and between 13 and 24 months (8 patients). In conclusion, selection of treatment modality for cerebral AVMs depends on the preoperative evaluation of the risk/benefit ratio in each case. Microsurgical removal, which eliminates the risk of bleeding immediately, is preferred for lesions in non-eloquent areas. Radiosurgery is an effective treatment modality for small lesions in eloquent areas, but has a substantial risk of haemorrhage during the latency period. Results of this study suggest that microsurgical removal should be considered for lesions in eloquent areas with high haemorrhage risk, such as prior haemorrhage, medium to large size lesion, and single deep venous drainage.

Adolescent↗
PubMed2000

A new strategy to predict the neoplastic polyps of the gallbladder based on a scoring system using EUS.

BACKGROUND: A new method to predict neoplastic polyps of the gallbladder using a scoring system based on five endoscopic ultrasonography (EUS) variables is presented. METHODS: EUS data from patients with gallbladder polyps who were to undergo cholecystectomy were used for the construction of an EUS scoring system in polyps between 5 and 15 mm in diameter (reference group). The EUS scoring system developed from those patients was applied to other patients (validation group). RESULTS: In the reference group, size was the most significant predictor of neoplastic polyp. All polyps 5 mm or less in diameter were non-neoplastic and 94% of polyps of greater than 15 mm were neoplastic in the reference group. For polyps between 5 and 15 mm in diameter, the area under the receiver-operating characteristic curves (ROC) plots for the endoscopic scoring system was significantly greater than that under the ROC plots for polyp size alone (p < 0.01). In the validation group, the risk of neoplastic polyp was significantly higher for polyps with a score of 6 or greater compared with those with a score of less than 6 (p < 0.01). CONCLUSIONS: Our data show that a score based on five EUS variables identifies those patients at risk of neoplasia when polyps are between 5 and 15 mm in diameter. (Gastrointest Endosc 2000;52:372-9).

Adult↗
PubMed2000

MRI features of infarcts with potential cardiac source of embolism in the Yonsei Stroke Registry (YSR), Korea.

The determination of the embolic source is crucial to understanding the pathogenesis of ischemic stroke, the initiation of appropriate therapy, and the prevention of recurrent infarctions. In this study we undertook to identify the characteristic features on magnetic resonance images of patients who had suffered from stroke due to cardiac embolism (CE), as classified by TOAST (possible and probable). We retrospectively studied magnetic resonance imaging (MRI) findings of patients with ischemic stroke from the Yonsei Stroke Registry (YSR). On the basis of the TOAST classification, 92 patients were identified to have a potential cardiac source of embolism (PCSE), in which 69 patients were found to have high-risk PCSE and 23 patients medium-risk PCSE. To compare their imaging characteristics, another group of 49 patients who were found to have had a stroke due to large artery-to-artery (ATA) embolism-common or internal carotid artery (CCA, ICA)-were identified. Involvement of the simultaneous superficial and deep territories (58.7%; 6.1%, p < 0.001), and combined new anterior and old posterior circulation (15.2%; 2.0%, p = 0.016) were more frequent in PCSE than ATA embolism. Bilateral anterior hemispheric involvement was also more frequent in the PCSE group, but it did not reach statistical significance (13.0%; 4.1%, p = 0.090). ATA embolism tended to involve only superficial territories compared to PCSE (71.4%; 28.3%, p < 0.001). There were no topographic differences between the high-risk and medium-risk groups. With respect to the etiology of PCSE in our population, atrial fibrillation was the most common. Characteristic MRI features of patients with PCSE, which were not documented previously by computed tomography (CT) included: old and new, involvement of multiple different vascular territories, bilateral anterior hemisphere, as well as anterior and posterior circulation. These MRI features, together with simultaneous superficial and deep territorial involvement, help to differentiate the underlying embolic sources, whether they are cardiac or ATA in origin.

Cerebral Infarction↗
PubMed2000

Diffuse cerebrospinal gliomatosis with extensive leptomeningeal spread.

A case of diffuse cerebrospinal gliomatosis with extensive leptomeningeal spread is presented. The patient, an 18-year-old girl, was admitted due to progressive weakness and paresthesia of both legs, following rapid neuropsychiatric deterioration. An initial magnetic resonance imaging (MRI) study of the T-spine showed diffuse high signal intensities from T9 to T12 spinal cords on a T2 sagittal image and diffuse cord bulging at T1WI. This suggested an inflammatory lesion such as tuberculosis or fungal meningoencephalitis. A limited autopsy was performed. A microscopic examination revealed multifocal GFAP-positive astrocytic proliferations that were low grade astrocytoma in the cerebral leptomeninges, parietal, occipital and temporal lobes and anaplastic astrocytoma in the spinal cord and spinal leptomeninges. The high proliferative indices of the spinal lesion and aneuploidy correspond to a diagnosis of malignant astrocytoma and a rapid fatal clinical course.

Adolescent↗