Biomedical subjects

S H Paek

Publications and source records attributed to S H Paek.

At least 19 recordsLinked to original sources

PubMed2003

The significance of gemistocytes in astrocytoma.

BACKGROUND: A retrospective clinical analysis of astrocytomas which contained a significant proportion of gemistocytes was carried out in order to evaluate their effect on prognosis, and other factors influencing prognosis. METHOD: From 253 consecutive cases of astrocytic tumours in adults, 25 were selected who had more than 20% gemistocytes in every high-power field examined. 9 of these had anaplasia, the remainder did not. They were divided into two groups according to the proportion of gemistocytes; group A, contained more than 60% gemistocytes, and group B, had between 20 and 60% gemistocytes. TUNEL and immunohistochemical staining for PCNA, p53, Ki-67, bcl-2 were performed in the 20 available cases. FINDINGS: The median follow-up period was 46 months. There were 14 recurrences, with a median time to recurrence of 15 months. Thirteen repeat operations were performed in nine cases, and two cases showed recurring malignant transformation. The overall median survival time following diagnosis was 73 months and the 5-year survival rate was 52%. There were no significant differences in median survival between groups A and B with different proportions of gemistocytes. On the other hand the median survival of the gemistocytic astrocytomas with anaplasia was 25 months, compared with 158 months for those without anaplasia (p=0.0005). The significant impact of anaplasia on survival persisted in both groups. There were no significant differences in immunohistochemical staining between the two groups, with the exception of staining for Ki-67 (means of the two groups: group A 1.40; group B 2.50). CONCLUSIONS: It is suggested that the proportion of gemistocytes does not itself affect prognosis.

Adult↗

PubMed2003

Changes in vascular responses of the basilar artery to acetylcholine and endothelin-1 in an experimental rabbit vasospasm model.

BACKGROUND: This study aimed to clarify the characteristics of the basilar arteries of rabbits two and seven days after subarachnoid haemorrhage (SAH) and to investigate the influence of hypoxia on vascular responses to acetylcholine and endothelin-1. METHODS: Thirty four New Zealand white rabbits were divided into 3 groups: 1) control (n=6), 2) 2 days post SAH (n=15), and 3) 7 days post SAH (n=13). Rabbits in the groups 2 and 3 underwent vertebral angiography before sacrifice. Harvested vascular rings were suspended in a small vessel myograph system for isometric tension recording in response to vasodilatory and vasoconstrictory stimulation in oxygenated (95% O2/5% CO2) and hypoxic (95% N2/5% CO2) conditions. To investigate the response to a vasodilator, acetylcholine (ACh) (10(-7) to 3 x 10(-4) M) was applied to a basilar artery pre-contracted with histamine (10(-6) approximately 10(-5) M). To investigate the response to a vasoconstrictor, the effect of endothelin-1 (ET-1) (10(-11) to 3 x 10(-8) M) was observed in quiescent rings. FINDINGS: Seven of 15 rabbits that underwent angiography two days after operation showed vasospasm to 64.3+/-11.2% of the original diameter; likewise seven of the 13 rabbits studied seven days after operation showed vasospasm to 64.9+/-10.9% of the original diameter. Hypoxic conditions significantly reduced the relaxation response to ACh but did not influence basilar artery contraction to ET-1. Responses to ACh and ET-1 did not differ significantly in vessels from animals with or without vasospasm at 2 days. In contrast, at 7 days vascular responses to ACh and ET-1 were significantly less in vessels from animals with vasospasm than those without (p=0.029, 0.032), and also less than in vessels from animals with vasospasm at day 2 (p=0.002, 0.004). There was not a significant difference in the vascular responses of basilar arteries from animals without vasospasm. INTERPRETATION: The markedly lower vascular responses of basilar arteries of rabbits to ACh and ET-1 found seven days after SAH may relate to delayed vasospasm in patients with SAH.

Acetylcholine↗

PubMed2003

Stereotactic biopsy for intracranial lesions: reliability and its impact on the planning of treatment.

BACKGROUND: The authors present a retrospective analysis of 308 computed tomography (CT)-guided stereotactic biopsies in 300 patients in order to evaluate the reliability and efficacy of the stereotactic biopsy for intracranial lesions. METHOD: All patients were suffering from undetermined intracranial lesions and treated at Seoul National University Hospital between January 1993 and December 1999. Age ranged from three to 79 years (mean 41); the male to female ratio was 180:120. All patients underwent CT-guided stereotactic biopsy for the histological verification and/or evacuation of the cyst using Riechert-Mundinger stereotactic system. FINDINGS: Histological diagnosis was made in 275 patients (diagnostic yield 91.7%). Diagnostic yield was better in group with frozen section examination during the stereotactic procedure than the group without it (p=0.01). Neoplastic lesions were more likely to be diagnosed in stereotactic biopsy than non-neoplastic lesions (p=0.02). Among 30 patients who underwent craniotomy after the stereotactic biopsy, the histological diagnoses after the craniotomy were identical to those of the stereotactic biopsy in 29 patients (diagnostic accuracy 96.7%). Two patients died within seven days after the stereotactic biopsy (mortality 0.6%). The postoperative new neurological deficit or aggravation of the neurological status was found in 19 patients, including transient cases of seven patients (permanent morbidity rate 3.9%). Histologically malignant gliomas and deeply-located lesions were the significant risk factors for the development of complications. In 148 cases, histological diagnosis of the stereotactic biopsy was different from the preoperative clinical diagnosis. Among these cases, the treatment plan was changed after stereotactic biopsy in 81 cases. CONCLUSIONS: Stereotactic biopsy for intracranial lesions is a reliable and relatively safe procedure. It is also a very efficacious method especially in patients who need histological confirmation for the treatment.

Adolescent↗

PubMed2002

Radiosurgery of intracranial cavernous malformations.

BACKGROUND: The efficacy of radiosurgery in cases of surgically high risk symptomatic cavernous malformations (CMs) for reducing haemorrhagic risk and for seizure control has not been clearly documented and the radiation-induced complications of radiosurgery remain problematic. The authors present a retrospective clinical analysis of 22 cases of CMs treated by radiosurgery. METHODS: Twenty-two patients with symptomatic CMs were treated by linear accelerator (LINAC) radiosurgery or Gamma knife (GK) between 1995 and 1998. Medical records including radiological investigations were carefully reviewed to the last follow-up. The mean age of the patients was 34.1 years (12-56) and the male to female ratio was 12:10. Twenty patients reported at least one episode of bleeding and four had undergone microsurgery before radiosurgery. The remaining two patients presented with seizure without evidence of recent haemorrhage. In 16 cases, the CMs were deep-seated, and the others were located in the cerebral hemispheres; four were located at an eloquent area. LINAC radiosurgery using computed tomography scan was performed in 11 cases until May 1997, after which GK radiosurgery using magnetic resonance (MR) image was performed in 11 cases. The volume of the lesion ranged from 0.09 cc to 4.8 cc (mean 1.42 cc) and the mean marginal dose was 16.1 Gy (8-24). The median follow-up period after radiosurgery was 38.3 months (21-67). The rate of haemorrhage, seizure, and neurological deterioration following radiosurgery was analyzed, and the rate of haemorrhage was compared to that seen in natural course reports. FINDINGS: There was one case of haemorrhage during the follow-up period and the seizure was well controlled with anticonvulsants. In the group with prior haemorrhage, the bleeding rate of cavernous malformation after radiosurgery (1.55%/year) was lower than that of pre-radiosurgical period (35.5%/year, t=1.296, P=0.04). Six patients showed neurological deterioration following radiosurgery, however, the neurological deficits persisted in only two of the patients with LINAC. The radiosurgical modality (LINAC vs. GK) showed a possible correlation to radiation induced neurological deficits (P=0.06). On the MR images at the last follow-up, the lesion was decreased in eleven patients, increased in one, and no change was found in 10 cases. The T2 weighted MR images revealed a perilesional high signal change in nine patients. This signal change was not statistically related to lesion size (P=0.236), location (P=0.658), nor radiation dose (P=0.363), but was dependent on the treatment modality (P=0.02). New-enhancing lesion and a new cyst were each found in one case, respectively, during the follow-up. INTERPRETATION: Radiosurgery may be a good alternative option for treatment of surgically high risk CMs. However, the optimal radiosurgical technique, dose adjustment, and proper delineation of the mass are prerequisites. Radiosurgery induced complications are still problematic and post-radiosurgery MR image changes need to be further elucidated.

Adolescent↗

PubMed2002

Cerebral germinoma with hemiatrophy of the brain: report of three cases.

BACKGROUND: The authors report three cases of cerebral germinoma that occurred in young adults with unusual presentation. METHOD: All three patients presented with hemiparesis and were treated at Seoul National University. A histological diagnosis of germinoma was made by a stereotactic biopsy in all three cases. FINDINGS: Magnetic resonance (MR) images showed that their tumors were located in the internal capsule and thalamus, and were associated with ipsilateral cerebral hemisphere and brain stem atrophy. The hemiparesis slowly progressed and this was accompanied by a haemorrhagic cyst in each patient. INTERPRETATION: Clinical diagnosis was not easy because of the unusual clinical presentations and atypical MR imaging findings. It is suggested that cerebral germinoma should be included in the differential diagnosis of a haemorrhagic mass which is associated with cerebral atrophy in the thalamus, basal ganglia, or internal capsule, especially in adolescents or young adults.

Adolescent↗

PubMed2001

Semiquantitative, bar code version of immunochromatographic assay system for human serum albumin as model analyte.

An immunochromatographic assay system was devised that can express the concentration ranges of analyte (e.g., urinary human serum albumin) as distinct numbers of the ladder bar (bar coding) for semiquantitation. We constructed a model system consisting of five membrane pad strips partially superimposed in a length. Upon wicking of sample from the bottom, the medium dissolved two different biotinylated species, antibody to the analyte and conjugates of the antibody with colloidal gold, and antigen-antibody reactions took place in the hollow space of the glass fiber membrane. After eliminating unreacted biotinylated molecules at the next strip with an immobilized albumin, the immune complexes were transferred to the pad with streptavidin immobilized in a ladder bar pattern. Analytical conditions here were set for competition between the two biotinylated species for the streptavidin binding sites. The degree of such competition was proportional to the analyte concentration and, consequently, the bar signal number was elevated as the concentration increased. Under optimal conditions for sensitivity, the analytical system responded to the analyte doses at between 30 and 120 mg/dL by producing different bar codes within 5 min.

Chromatography↗

PubMed2001

Visual information processing using bacteriorhodopsin-based complex LB films.

Image extraction and visual information processing using bacteriorhodopsin (bR)-based bioelectronic devices is presented. Image extraction was achieved using a photoreceptor consisting of bR and spiropyran films. The undesired signals from the photoreceptor were automatically eliminated from the whole signal by spiropyran films acting as an optical noise filter that increases the target signal to an undesired signal ratio. For the information processing, the photoreceptor consisting of bR and lipid films deposited with different configurations was used and the target signals were processed to achieve the pattern recognition. The pattern recognition was based on not only the response variability of bacteriorhodopsin, induced by different film configurations, but also on the initial learning process. The input patterns were predicted by simple calculation with the known signals through the initial learning process.

Bacteriorhodopsins↗

PubMed2001

Postoperative spinal seeding of craniopharyngioma. Case report.

The authors present a case of postoperative spinal seeding of papillary craniopharyngioma. This 27-year-old man who had previously undergone subtotal removal of a suprasellar craniopharyngioma was admitted because of low-back and right leg pain. Results of neurological examination showed a limitation in straight-leg raising in the right side with no sensorimotor changes. Magnetic resonance imaging of the lumbar spine demonstrated multiple enhanced intradural extramedullary masses causing spinal cord compression. Pathological examination of the tumor tissue obtained via laminectomy revealed papillary craniopharyngioma, which had the same histological features as those of the previous suprasellar tumor. Several ectopic recurrences of craniopharyngioma have been reported; however, the authors believe that this is the first published report of the spinal seeding of craniopharyngioma.

Adult↗

PubMed2001

The detection of p53 gene mutation using a microdissection technique in primary intracranial germ cell tumors.

Using a microdissection technique, the contribution of the p53 mutation to tumorigenesis and prognosis in each histological subtype of the intracranial germ cell tumors (GCTs) was evaluated. Nineteen patients had primary intracranial GCTs, including 4 germinomas (GEs), 4 teratomas (TEs), 1 mixed tumor of GE and TE, and 10 mixed GCTs containing non-germinomatous malignant germ cell tumors (NG-MGCTs). After microdissection of specific subtypes, genomic DNA was screened for mutations in exons 5-8 of the p53 gene, using the dideoxyfingerprinting (ddF) followed by direct DNA sequencing. The direct sequencing revealed a total of six mutations in PCR products derived from the five cases (26%) which showed mobility shifts in ddF. Among the six mutations detected, four were missense mutations and two were silent. Missense mutations of the p53 gene tended to occur more frequently in the NG-MGCT component than in the GE or TE components (3/15 vs. 1/12 vs. 0/13). The incidence of missense mutations was not different between the survivors (3/13) and the deceased (1/6). This study suggests the possible role of the p53 gene in the tumori-genesis of NG-MGCT. However, p53 gene mutation did not correlate with the prognosis of NG-MGCT.

Adult↗

PubMed2000

Differential effects of cholera toxin and pertussis toxin on the c-fos and c-jun mRNA expression in rat C6 glioma cells.

Cholera toxin (CTX) increased c-fos mRNA level whereas it down-regulated the c-jun mRNA level in rat C6 glioma cells. In contrast to the action of CTX, pertussis toxin (PTX) did not affect either c-fos or c-jun mRNA level. The elevated c-fos mRNA level induced by CTX was significantly inhibited by the co-treatment with dexamethasone (DEX). However, DEX did not affect CTX-induced down-regulation of c-jun mRNA level. Cycloheximide (CHX) increased c-fos and c-jun mRNA levels. CHX caused a super-induction of CTX-induced c-fos mRNA level. Our results suggest that CTX-, but not PTX-, sensitive G-proteins may play an important role for c-fos mRNA up-regulation and c-jun mRNA down-regulation. In addition, DEX appears to have a selective inhibitory action against c-fos mRNA expression regulated by CTX. Ongoing protein synthesis inhibition is required for the superinduction of c-fos, but not c-jun, mRNA induced by CTX.

Animals↗

PubMed2000

Development of rapid one-step immunochromatographic assay.

An analytical system for a one-step immunoassay has been constructed using the concept of immunochromatography. The system employed two different antibodies that bound distinct epitopes of an analyte molecule: an antibody labeled with a signal generator (e.g., colloidal gold), which was placed in the dry state at a predetermined site on a glass-fiber membrane, and another antibody immobilized on the surface of a nitrocellulose membrane. Three membranes, one with the tracer, one with immobilized antibody, and a cellulose membrane as the absorbent of medium (in a sequence from the bottom), were attached to a plastic film and cut into strips. Aqueous medium containing analyte absorbed from the bottom end of the immunostrip dissolved the labeled antibody, and the antigen-antibody binding complex formed was transported into the next nitrocellulose membrane by the flow caused by capillary action. The complex subsequently reacted with the immobilized antibody, which generated a signal in proportion to the analyte concentration. The convective mass transfer of the immunoreactant to the binding partner allowed the assay to be performed with no handling of reagents. The reaction, however, was carried out under nonequilibrium conditions, which resulted in decreased sensitivity as compared with assays performed in an equilibrium mode (e.g., ELISA). To minimize such sacrifice, major factors that control system performance were identified and the system was then devised under optimal conditions.

Animals↗

PubMed2000

Clinical feature and outcome of pediatric cerebrovascular disease: a neurosurgical series.

To investigate the clinical features and surgical outcome of pediatric cerebrovascular disease (CVD), we retrospectively reviewed 280 children (up to 15 years of age) who underwent neurosurgical procedures for CVD between 1979 and 1998. Open surgery (n=448), endovascular procedures (n=22), and stereotactic radiosurgery (n=14) were the main neurosurgical procedures adopted. Clinical features and surgical outcomes were described according to the etiology of the CVD and the number of years of management. The mean duration of follow-up was 34 months. The mean age was 7.1 years, and the male-to-female ratio was 1.2:1. The most frequent CVD was moyamoya disease (62%). The surgical mortality related to CVD was 0.7%. Eighty-seven percent had Karnofsky Performance Scale scores of more than 70. We demonstrate increasing detection rates and improving outcomes in recent years. The clinical course in this study shows that recovery from CVD in children is good after neurosurgical procedures.

Adolescent↗

PubMed2000

Meningioma manifesting intracerebral haemorrhage: a possible mechanism of haemorrhage.

We present a possible mechanism of intracerebral peritumoural haemorrhage in meningioma based on the clinical data of three of our cases. A meningioma manifesting intracerebral haemorrhage is uncommon and some sporadic case reports have been presented, but without any proven mechanisms. We are presenting three cases of convexity meningioma manifesting spontaneous intracerebral haemorrhage with apoplectiform onset. All three patients had no evidence of bleeding tendency or other predisposing factors for haemorrhage. Preoperative radiological studies showed a solid mass attached to the dura with intracerebral peritumoural haematoma. Total removal of the tumour and haematoma could be achieved in every case. Histological investigation revealed extensive tumour infarction in two cases and fibrosis related to pre-existing ischaemia in the other case. The diagnoses were atypical meningioma in two cases and transitional type in one case. We suggest that extensive tumour infarction might be a cause of spontaneous intracerebral peritumoural haemorrhage in our series of patients.

Aged↗

PubMed2000

Conductimetric membrane strip immunosensor with polyaniline-bound gold colloids as signal generator.

For point-of-care examination, an immuno-chromatographic assay system based on conductimetric detection was investigated by utilizing, as signal generator, colloidal gold with polyaniline bound on the metal surface. Although the gold is a widely used label for antibodies to produce colorimetric signals, the tracer does not lend itself for a suitable electric conduction along the gold particles due to the presence of protein barriers (e.g. immunoglobulin and blocking agent) against electron transfer. To overcome this problem, we introduced a conducting polymer, for instance, polyaniline, as a conductivity-modulating agent on the gold surface after immobilizing an antibody specific to human albumin used as model analyte. This novel signal generator amplified the conductimetric signal 4.7 times compared with the plain gold, and the signal was also maximum 2.3-fold higher than that from the photometric system under the same analytical conditions. The latter effect resulted from an exponential pattern in the dose-response curve of the electric signal that was different from the conventional sigmoidal shape.

Aniline Compounds↗

PubMed2000

Long-term outcome and growth rate of subtotally resected petroclival meningiomas: experience with 38 cases.

OBJECTIVE: To evaluate the long-term outcome of a subtotally resected residual tumor and to assess its growth rate, we analyzed the records of 38 patients with residual petroclival meningioma. METHODS: Clinical records and radiological findings of 38 cases of petroclival meningioma that were diagnosed and subtotally resected at Seoul National University Hospital between 1981 and 1997 were carefully reviewed. Follow-up imaging studies were reviewed, and Karnofsky performance scale scores at the last follow-up were recorded. The duration of follow-up ranged from 6 to 141 months (mean, 47.5 mo; median, 30 mo). Tumor progression and progression-free survival rates were assessed. The growth rate of a residual tumor was evaluated by measuring the equivalent diameter and the tumor volume serially; the tumor doubling time was calculated, and the predictive factors for determining the growth pattern in residual tumors and the prognosis were analyzed. RESULTS: In 33 (87%) of the 38 patients, Karnofsky performance scale scores at the last follow-up were 80 or above. The median progression-free survival time among patients with subtotally resected tumors was 66 months, and the 5-year progression-free survival rate was 60%. The growth rate of residual tumors was low (volume increase, 4.94 cc/yr; diameter increase, 0.37 cm/yr). The mean tumor doubling time was 8 years. Although there were no significant predictive factors, age and extent of tumor resection seemed to influence the progression-free survival rate. Significant factors affecting the growth rate were age and occurrence of menopause. CONCLUSION: Subtotal resection with or without radiation or radiosurgery should be considered as a suitable treatment option for patients with petroclival meningiomas, especially the elderly, because the growth rate of residual tumors is low.

Adolescent↗

PubMed2000

Gamma knife radiosurgery as a primary treatment for prolactinomas.

OBJECT: The purpose of this study was to estimate the efficacy of gamma knife radiosurgery (GKS) in controlling tumor growth and endocrinopathy associated with prolactinomas. METHODS: Between 1993 and 1997, 164 of 469 patients with pituitary adenomas treated by GKS harbored prolactinomas. The dose to the tumor margin ranged from 9 to 35 Gy (mean 31.2 Gy), and the visual pathways were exposed to a dose of less than 10 Gy. The mean tumor diameter was 13.4 mm. The mean follow-up time for 128 cases was 33.2 months (range 6-72 months). Tumor control was observed in all but two patients who underwent surgery 18 and 36 months, respectively, after GKS. Clinical cure was achieved in 67 cases. Clinical improvement was noted with a decrease in the hyperprolactinemia after GKS. Nonetheless, in 31 (29%) of 108 patients who were followed for more than 2 years no improvement in serum prolactin levels was demonstrated, although this could be normalized by bromocriptine administration after treatment. Nine infertile women became pregnant 2 to 13 months after GKS and all gave birth to normal children. There was no visual deterioration related to GKS. Five women experienced premature menopause. In these patients there was subtotal disappearance of the tumor and an empty sella developed. CONCLUSIONS: Gamma knife radiosurgery as a primary treatment for prolactinomas can be safe and effective both for controlling tumor growth and for normalization of prolactin hypersecretion. A higher margin dose (> or = 30 Gy) seemed to be associated with a better clinical outcome. Gamma knife radiosurgery may make prolactinomas more sensitive to the bromocriptine.

Humans↗

PubMed1999

Immunochromatographic membrane strip assay system for a single-class plasma lipoprotein cholesterol, exemplified by high-density lipoprotein cholesterol measurement.

In assessing risk factors of coronary heart disease, a membrane immunochromatographic system that minimizes requirements of instrument and reagent handling was investigated by utilizing high-density lipoprotein (HDL) cholesterol (HDL-C) as model analyte. The system is composed of four functional membrane strip pads connected in sequence as follows (from the bottom): immunoseparation based on the biotin-streptavidin reaction; catalytic conversion of cholesterol to hydrogen peroxide; production of a colorimetric signal; and induction of a continuous wicking of medium. For immunochromatography, a monoclonal antibody, specific to apolipoprotein B100 that is present on the surfaces of low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL), with a high binding constant (5 x 10(10) L/mol), was raised and chemically conjugated to streptavidin. The conjugate was first reacted with lipoprotein particles, and this mixture was absorbed by the capillary action into the biotin pad of the system. After being transferred by medium, immunocapture of LDL and VLDL particles onto the biotin pad took place, and in situ generation of a colorimetric signal in proportion to HDL-C occurred consecutively. The capture was selective as well as effective (minimum 88% of LDL and VLDL in clinical concentration ranges), and the detection limit of the HDL-C was far lower than 20 mg per 100 mL. The same concept may also be applicable to LDL cholesterol measurement provided suitable antibodies specific to HDL and VLDL are available.

Animals↗

PubMed1999

Outcomes of medical treatment of neurocysticercosis: a study of 65 cases in Cheju Island, Korea.

BACKGROUND: Although cysticidal drugs hasten the death and disappearance of the parasite, the long-term prognosis of NCC is still not satisfactory. METHODS: In this study, 65 patients with active neurocysticercosis (NCC) treated with praziquantel or albendazole were retrospectively reviewed to evaluate radiological and clinical outcome. According to worm location, patients were divided into two groups: parenchymal (n = 42) and extraparenchymal NCC (n = 23). The average duration of follow-up was 23 months. RESULTS: In terms of cysticidal effectiveness (73% vs. 50%), seizure control (60% vs. 43%) and symptomatic improvement of non-seizure patients (64% vs. 44%), the outcome of treatment was better in the parenchymal NCC than in the extraparenchymal. Repeated cysticidal treatment was needed in 26% of parenchymal and 39% of extraparenchymal NCC. After treatment, 38% of parenchymal NCC complained of seizure and 35% suffered from headache. Likewise, 27% and 36% of extraparenchymal NCC complained of seizure and headache, respectively. During the follow-up, 7 of 30 patients without initial seizure developed new seizures after medical treatment. CONCLUSION: Despite the development of cysticidal drugs, a considerable number of patients suffer from late neurologic sequelae such as seizure and headache. Therefore continuous attention should be given to the patients after cysticidal treatment. Prevention by health education is emphasized.

Adolescent↗