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Biomedical subjects

K S Choi

Publications and source records attributed to K S Choi.

At least 91 records · Page 5Linked to original sources
PubMed1990

Gd-DTPA enhanced MR imaging in intracranial tuberculosis.

Twenty-six patients with intracranial tuberculosis (Tb) (10 with acute meningitis, 5 with chronic meningitis, 5 with meningitic sequelae and 6 with localized tuberculoma(s)) were examined with MR before and after Gd-DTPA enhancement (0.1 mmol/kg), using 2.0T superconducting unit, and the images were retrospectively analyzed and compared with CT scans. Without Gd-DTPA enhancement, the MR images were generally insensitive to detection of active meningeal inflammation and granulomas. The signal intensity of granulomas was usually isointense to gray matter on both T1- and T2-weighted images, whether they were associated with diffuse meningitis or presented as localized tuberculoma(s). A few granulomas showed focal hypointensity on T2-weighted images. Calcifications seen on CT of the meningitic sequelae group usually appeared markedly hypointense on all spin-echo sequences. On Gd-DTPA enhanced T1-weighted images, abnormal meningeal enhancement indicating active inflammation was conspicuous, and the granulomas often appeared as conglomerated ring-enhancing nodules, which seems to be characteristic of granulomas. Thin rim enhancement around the suprasellar calcifications were observed in two out of 5 patients with meningitic sequelae. Compared with CT, MR detected a few more ischemic infarcts, hemorrhagic infarcts, meningeal enhancement and granulomas in the acute meningitis group, but missed small calcifications in the basal cisterns well shown on CT in the sequelae group. Otherwise, MR generally matched CT scans. MR imaging appears to be superior to CT in evaluation of active intracranial Tb only if Gd-DTPA is used, while CT is better than MR in evaluating meningitic sequelae with calcification.

Adolescent↗
PubMed1990

The fate of spargana inoculated into the cat brain and sequential changes of anti-sparganum IgG antibody levels in the cerebrospinal fluid.

To establish an animal model of intracranial sparganosis, the fate and behavior of the experimentally inoculated spargana were observed. A total of 102 scolices of spargana were injected into 22 cat brains, and the cats were sacrificed at 2 weeks, 1 month, 3 months and 6 months after the inoculation. Neurosparganosis was established in 77% of the cats. Of 43 recovered worms, 19 (44%) were located in the subdural or subarachnoid space, 16 (37%) in the brain parenchyme, and 2 (5%) in the lateral ventricle. One was detected at the diploic space of the skull and 5 were outside the cranial cavity. All but one were alive, and had grown tails. They were distributed in the brain parenchyme randomly. There was no place which they could not invade. No adult was found in the intestine. Cerebrospinal fluid (CSF) was collected before inoculation, 1 week, 2 weeks, 1 month, 3 months and 6 months after inoculation. The level of anti-sparganum IgG antibody in CSF measured by ELISA began to increase above the criteria of positivity 1 month after inoculation. Three months after inoculation, the values markedly increased. The present findings reveal that intracranial inoculation of spargana into the brains of cats would be a good animal model of experimental neurosparganosis.

Animals↗
PubMed1988

Acute cerebral infarction and changes of regional cerebral blow flow (rCBF) following experimental middle cerebral artery (MCA) occlusion.

An unanaesthetized cat model of acute focal cerebral ischaemia has been established by the technique of transorbital snare ligature for middle cerebral artery (MCA) occlusion. The model was used to investigate the patterns of changes of regional cerebral blood flow (rCBF) for up to 16 h following MCA occlusion by the hydrogen clearance technique and to explore the correlation among changes of rCBF, neurological deficits, and pathological changes. The animals were divided into 2 groups according to the size of infarct which was identified by 2% triphenyl tetrazolium chloride (TTC) solution stain. Infarct larger than 10% of coronal section surface of ipsilateral hemisphere was found in 18 cats (Group A), and a smaller infarct was found in the remaining 7 cats (Group B). Between these 2 groups, there was a statistically significant difference in the average rCBF value of the ipsilateral MCA territory. The increasing grade of contralateral paralysis correlated well with the decreasing rCBF in the ipsilateral MCA territory, and the increasing grade of cerebral hemispheric swelling was directly proportional to the increasing grade of paralysis. Three patterns of changes of rCBF were observed: persistent severe ischaemia (15 cats, Group A); persistent mild to moderate ischaemia (7 cats, Group B); and immediate severe ischaemia followed by early post-ischaemic hyperaemia and death (3 cats, Group A). During the initial stage of ischaemia, a significant decrease in rCBF of the contralateral hemisphere was observed in both groups, however, in Group A rCBF gradually increased to preocclusion level, while Group B presented a further decrease in rCBF suggesting the occurrence of interhemispheric diaschisis. Thus, Group B appeared to take advantage of diaschisis during the late phase of infarct development, as well as the substantial collateral flow from the surrounding anterior and posterior cerebral artery territories.

Animals↗
PubMed1987

Cerebral sparganosis: CT characteristics.

Cerebral sparganosis is an extremely rare parasitic zoonosis caused by a migrating plerocercoid tapeworm larva, genus Spirometra. Nineteen computed tomography (CT) scans of 12 patients with cerebral sparganosis were retrospectively analyzed and correlated with clinical and pathologic data. On CT scans, the following characteristics were noted: (a) unilateral involvement; (b) extensive or multifocal areas of low density along white matter bundles, with ipsilateral ventricular dilatation and localized cortical atrophy; (c) nodular or irregular enhancement with spotty calcification; and (d) change in location of enhancing nodules on sequential scans. These pathognomonic features reflect a chronic inflammatory process with both active granulomatous lesions and widespread degeneration of brain tissue, especially in the white matter. Degeneration is probably caused by migration of the long-surviving larva along the fiber tracts of white matter.

Adult↗
PubMed1987

[The effects of teacher expectancy and self-expectancy on performance].

The present study was designed to investigate the effect on performance of the relationship between teacher expectancy and self-expectancy. For the induced expectancy, a random half of 96 high school students enrolled in a four-week summer language course of a Christian association were described to the instructors as having high success potential. The remaining trainees served as controls. Correct scores on the learning task, instructor ratings of behavior and attitude of the instructors were measured on three sessions of the course. Ratings of teacher's behavior were factor-analyzed and four interpretable factors emerged: Support, Caring, Attention, and Tutoring. The induced expectancy and specific levels of self-expectancy had significant effects on the subjects' performance and ratings of the instructor. It was concluded that self-expectancy mediates the effects of teacher expectancy on learning performance. Implications of these results for the Pygmalion effect were discussed.

Achievement↗
PubMed1966

[Typhoid fever].

Explore the source record for details and available documents.

Nursing↗
PubMedDate not supplied

Pineal tumors: experience with 48 cases over 10 years.

The authors retrospectively reviewed 48 patients treated at Seoul National University Hospital (SNUH) between 1986 and 1995. There were 35 children and 13 adults, accounting for 10.1% of 345 pediatric and 0.68% of 1914 adult brain tumors in SNUH during the same period. The 48 cases consisted of 33 cases of germ cell tumor (69%, GCT); 6 of pineoblastoma (PB, 12.5%); 3 of pineocytoma (PC, 6.3%); 3 of anaplastic astrocytoma (6.3%); 1 of astrocytoma; 1 of glioblastoma; and 1 of ependymoma. The median age was 13 years (range 1-59) and the male-to-female ratio was 3.36:1. The most frequent presenting symptom was due to increased intracranial pressure (90%), followed by Parinaud syndrome or diplopia (50%). Patients with a benign tumor, such as teratoma (TE), astrocytoma, or ependymoma, underwent surgery by the occipital transtentorial approach (OTT) for attempted radical resection without adjuvant therapy, while patients with immature teratoma (imTE), PC, and anaplastic astrocytoma underwent regional radiotherapy (RT) after debulking via OTT. Seven patients with nongerminomatous malignant GCT (NG-MGCT) and 3 with germinoma (GE) underwent craniospinal radiation only, 6 with GE, a NG-MGCT, and 2 with GE+TE received craniospinal radiotherapy (CSRT) after debulking via OTT. Three patients with GE, 4 with NG-MGCT, and 3 with PB underwent radiochemotherapy after debulking via OTT. Forty-four patients were followed up after treatment. The median follow-up period was 36 months. All patients with GE were alive after RT at 36 months (median) of follow-up (range 7-70 months). All with GE+TE and TE were alive. Three patients with PC or astrocytoma were also alive with stable or no evidence of disease. In 1 of the 3 cases of imTE there was a recurrence. However, 4 patients with NG-MGCT died, all of whom had undergone CSRT only; 2 PB patients were alive (12, 19 months), 1 in a moribund status (36 months), and 2 were dead (6, 60 months). The overall mean survival time with pineal tumors was 66 months and the 3-year survival rate was 84% with minimal posttreatment complications. It is concluded that pineal region tumors have male and childhood predominances, and the most common tumor is GCT. The majority of pineal region tumors are malignant. Pineal region tumors can be approached safely and effectively and the surgical complications are mostly transient. Their prognosis is dependent on the pathologies and treatment modalities.

Adolescent↗
PubMedDate not supplied

Bacterial adhesion on PEG modified polyurethane surfaces.

Polyurethane surface was modified with poly(ethylene glycol) (mol. wt. 1000, PEG1k) carrying terminal hydroxyl, amino and sulfonate groups, poly(ethylene glucol) (mol. wt. 3350, PEG3.4k) and PEG3.4k-Heparin, respectively. These surfaces were investigated for bacterial adhesion using S. epidermidis and E. coli in tryptic soya broth (TSB), brain heart infusion (BHI), and human plasma. All PEG modified surfaces reduced bacterial adhesion significantly and the adhesion level differs depending on surfaces as well as media. In the case of PEG1k surfaces, no reduction of S. epidermidis adhesion was demonstrated in TSB media, regardless of terminal functional groups of PEG1k. However, adhesion in plasma was reduced to the different degree, depending on terminal groups of PEG1k (least adhesion on sulfonated PEG surface). Relatively longer PEG surface (PEG3.4k) and PEG3.4k-heparin surface minimized bacterial adhesion in both media. In the case of E. coli adhesion, significant reduction in adherent bacteria was observed on all PEG1k, PEG3.4k, and PEG-heparin surfaces in both media compared to controls. In contrast, no reduction in bacterial adhesion was demonstrated on poly(propylene glycol) (PPG1k) grafted PU surface as compared to control PU. These results suggest that surface modification with PEG1k-SO3, PEG3.4k and PEG3.4k-heparin seems to be effective for prevention of bacterial adhesion and subsequent infection.

Animals↗
PubMedDate not supplied

Role of annexin II tetramer in plasminogen activation.

The enzymatic cascade triggered by activation of plasminogen has been implicated in a variety of normal and pathologic events, such as fibrinolysis, wound healing, tissue remodeling, embryogenesis, and the invasion and spread of transformed tumor cells. Recent data established that the Ca(2+)- and phospholipid-binding protein, annexin II heterotetramer (AIIt) binds tissue-type plasminogen activator (tPA), plasminogen, and plasmin, and dramatically stimulates the tPA-dependent conversion of plasminogen to plasmin in vitro. Interestingly, the binding of plasmin to AIIt can inhibit the activity of the enzyme, suggesting that plasmin bound to the cell surface is regulated by AIIt. The existing experimental evidence suggests that AIIt is the key physiological receptor for plasminogen on the extracellular surface of endothelial cells.

Animals↗
PubMedDate not supplied

Air pollution, temperature, and regional differences in lung cancer mortality in Japan.

In this study, the authors investigated regional differences in lung cancer mortality in Japan, and, based on data acquired between 1970 and 1990 for 47 Japanese prefectures, estimated the relationship between regional lung cancer mortality and air pollution and/or temperature. Investigators used data for nitrogen dioxide, sulfur dioxide, motor vehicle density, tobacco expenditure, and temperature as independent variables for age-adjusted lung cancer death rates. The age-adjusted lung cancer death rates were higher in the southern geographical block of Japan (i.e., approximately 1.2-fold in males and 1.1-fold in females) and in the northern block (approximately 1.2-fold in males) than in the central block. The regional differences in the age-adjusted lung cancer death rates were explained by nitrogen dioxide and temperature. Temperature caused a greater effect (regression coefficients) of nitrogen dioxide on the age-adjusted lung cancer death rates than did nitrogen dioxide alone in the southern block (i.e., approximately 1.3-fold in males and 1.2-fold in females). These results provide the first evidence of a possible synergistic interaction between air pollution and high temperature on lung cancer mortality.

Air Pollution↗