Biomedical subjects

H W Nam

Publications and source records attributed to H W Nam.

At least 19 recordsLinked to original sources

PubMed2003

Intracranial ictal onset zone in nonlesional lateral temporal lobe epilepsy on scalp ictal EEG.

OBJECTIVE: To determine the ictal focus and the role of seizure characteristics, fluorodeoxyglucose (FDG) PET, and subtraction ictal SPECT in patients diagnosed as having nonlesional lateral temporal lobe epilepsy by long-term scalp video-EEG monitoring. METHODS: The authors studied 33 consecutive patients with nonlesional neocortical epilepsy who had a scalp ictal onset zone localized in the temporal lobe and good surgical outcome after focal neocortical resection. All patients were evaluated using intracranial recordings prior to resection. Semiology, FDG-PET, and ictal-interictal subtraction SPECT were used to verify the diagnostic role of these methods in the localization of epileptic foci. RESULTS: The ictal onset zones, confirmed by intracranial study, were the lateral temporal (22 patients), parietal (5), frontal (3), temporoparietal (2), and occipital (1) areas. FDG-PET analyzed by statistical parametric mapping correctly localized the epileptogenic lobe in 18 of 33 patients and subtraction ictal SPECT correctly localized it in 13 of 25 patients. However, in patients with extratemporal ictal onset zones, FDG-PET and ictal SPECT in combination correctly localized the epileptogenic lobe in only 3 of 11 cases. CONCLUSIONS: An extratemporal ictal onset zone was encountered in patients with nonlesional lateral temporal lobe seizures based on scalp video-EEG monitoring. FDG-PET and subtraction SPECT had localizing value in no more than half of patients.

Adult↗

PubMed2001

Protease activity and host cell binding of the 42-kDa rhoptry protein from Toxoplasma gondii after secretion.

Three proteases were identified in the excretory/secretory proteins (ESP) from Toxoplasma gondii by the gelatin acrylamide gel electrophoresis (GAGE), of which the molecular masses were 80, 70, and 42 kDa. One of the proteases with 42 kDa was reactive to a monoclonal antibody (mAb), Tg786 clone, which was localized in the rhoptry of T. gondii by immunohistochemistry. The protease was maximally active at the pH range between 7.5 and 8.5, and was sensitive to inhibition by TPCK and EGTA. The gelatinolytic activity of the protease was dependent on the concentration of calcium ion. The protease was active only in the millimolar ranges of calcium but not in micromolar ranges, implicating that the secretion is critical event for the activation of the protease. The secreted protease was shown to bind to the host cells upon Western blot and immunofluorescence analysis. It is suggested that the protease may target to the plasma membrane of the host cells, which provides appropriate environment for the entry of the parasite into host cells. The mAb (Tg786) of T. gondii also reacted with a protein of the same size and equivalent locality of rhoptry in Neospora caninum, a similar Apicomplexan protozoa, suggesting that secreted protease mediates a common function in the mechanism of entry into host cells.

Animals↗

PubMed2001

Neuroimaging findings of cortical dyslamination with cytomegaly.

PURPOSE: Our aims were to identify (a) the characteristic magnetic resonance imaging (MRI) findings of cortical dyslamination with cytomegaly, including dysplastic and destructive lesions; (b) the relationship between MRI findings and pathologic characteristics; (c) the diagnostic role of functional neuroimaging studies in patients with these pathologies. METHODS: The series consisted of 23 adult patients who had proven cortical dyslamination with cytomegaly. The abnormalities found on MRI were subdivided according to the patterns of involvement. They also were compared with the patients' pathologic characteristics. With visual qualitative analysis, [18F]fluorodeoxyglucose with positron emission tomography (FDG-PET), and ictal single-photon emission computed tomography (SPECT), observations were classified as localizing, lateralizing, nonlateralizing, false-localizing, and false-lateralizing. The standard for correct localization of neuroimages was defined to be the resected lobe. RESULTS: Focal abnormalities were found in 14 cases by MRI. Six cases showed typical MRI findings of focal cortical dysplasia, with focal areas of cortical thickening with or without poor grey-white matter differentiation. Focal subcortical high signal intensities on T2-weighted images occurred in two cases. Six patients had the focal destructive pattern. Three of eight cases with normal MRI and four of eight cases with the nondestructive cortical dysplasia pattern had balloon cells. However, these were not found in six patients with the destructive MRI pattern. FDG-PET localized the pathologic lobe in 13 (65%) of 20 cases, and ictal SPECT achieved this in 11 (61.1%) of 18 cases. FDG-PET and ictal SPECT also correctly localized the pathologic lobe in four and two cases with normal MRI, respectively. CONCLUSIONS: Two distinct patterns of abnormal MRI were found in the pathology of cortical dyslamination with cytomegaly. These dysplastic and destructive patterns might reflect different pathogeneses, such as the time of insult. FDG-PET and ictal SPECT have confirmatory and independent diagnostic roles in localizing epileptogenic foci.

Adult↗

PubMed2001

Detection and characterization of excretory/secretory proteins from Toxoplasma gondii by monoclonal antibodies.

Excretory/secretory proteins (ESP) from Toxoplasma gondii were analyzed to define the function in the penetration process into host cells. Whole ESP obtained at 37 degrees C were composed of 15 bands with molecular mass of 110, 97, 86, 80, 70, 60, 54, 42, 40, 36, 30, 28, 26, 22, and 19 kDa. Five ESP of 86, 80, 42, 36, and 28 kDa were reacted with monoclonal antibodies (mAb), named as Tg386 (microneme), Tg485 (surface membrane), Tg786 (rhoptry), Tg378, and Tg556 (both dense granules), respectively. The ESP was released by a temperature-dependent/-independent manner and all at once whenever ready to pour out except Tg786. Each ESP was not exhausted within the parasite but the amount was limited. Tg786 was released continuously with increment, whereas Tg378 and Tg556 were ceased to release after 3 and 4 hr. Dense granular Tg378 and Tg556 were released spontaneously and constitutively before the entry into host cells also. The entry of T. gondii was inhibited by all the mAbs differentially. And the parasite deprived of ESP was inhibited to enter exponentially up to 90.1%. It is suggested that ESP play an essential function to provide appropriate environment for the entry of the parasite into host cells.

Animals↗

PubMed2001

Molecular cloning and characterization of peroxiredoxin from Toxoplasma gondii.

A cDNA of 1.1 kb comprising the gene encoding the peroxiredoxin of Toxoplasma gondii (TgPrx) has been cloned. The open reading frame of 591 bp was translated into a protein of 196 amino acids with a molecular mass of 25 kDa. Conserved 2 cysteine domains of Phe-Val-Cys-Pro and Glu-Val-Cys-Pro indicated TgPrx belonged to 2-Cys Prx families. TgPrx showed the highest homology with that of Arabidopsis thaliana by 53.9% followed by Entamoeba histolytica with 39.5% by the amino acid sequence alignment. Polyclonal antibody against recombinant TgPrx detected 25 kDa band in T. gondii without binding to host cell proteins. TgPrx was located in the cytoplasm of T. gondii extracellularly or intracellularly by immunofluorescence assay. The expression of TgPrx was increased as early as 30 min after the treatment with artemisinin in the intracellular stage, while no changes in those of host Prx I and TgSOD. This result implies that TgPrx may function as an antioxidant protecting the cell from the attack of reactive oxygen intermediates. It is also suggested that TgPrx is a possible target of chemotherapy.

Amino Acid Sequence↗

PubMed2001

Western blot diagnosis of vivax malaria with multiple stage-specific antigens of the parasite.

Western blot analysis was performed to diagnose vivax malaria using stage-specific recombinant antigens. Genomic DNA from the whole blood of a malaria patient was used as templates to amplify the coding regions for the antigenic domains of circumsporozoite protein (CSP-1), merozoite surface protein (MSP-1), apical merozoite antigen (AMA-1), serine repeat antigen (SERA), and exported antigen (EXP-1) of Plasmodium vivax. Each amplified DNA fragment was inserted into a pGEX-4T plasmid to induce the expression of GST fusion protein in Escherichia coli by IPTG. The bacterial cell extracts were separated on 10% SDS-PAGE followed by western blot analysis with patient sera which was confirmed by blood smear examination. When applied with patient sera, 147 (91.9%) out of 160 vivax malaria, 12 (92.3%) out of 13 falciparum malaria, and all 9 vivax/falciparum mixed malaria reacted with at least one antigen, while no reactions occurred with 20 normal uninfected sera. In the case of vivax malaria, CSP-1 reacted with 128 (80.0%) sera, MSP-1 with 102 (63.8%), AMA-1 with 128 (80.0%), SERA with 115 (71.9%), and EXP-1 with 89 (55.6%), respectively. We obtained higher detection rates when using 5 antigens (91.9%) rather than using each antigen solely (55.6-80%), a combination of 2 (76.3-87.5%), 3 (85.6-90.6%), or 4 antigens (89.4-91.3%). This method can be applied to serological diagnosis, mass screening in endemic regions, or safety test in transfusion of prevalent vivax malaria.

Animals↗

PubMed2001

Determination of antigenic domain in GST fused major surface protein (Nc-p43) of Neospora caninum.

The antigenic domain of the major surface protein (Nc-p43) of Neospora caninum was examined by polymerase chain reaction of its gene fragments and recombinant expression as GST fusion proteins. The fragments of Nc-p43 were as follow: a total open reading frame (OFR), T; OFR without signal sequence and C-terminal hydrophobic sequence, S; N-terminal 2/3 parts of S, A; C-terminal 2/3 parts, P; N-terminal 1/3 part, X; middle 1/3 part, Y; and C-terminal 1/3 part, Z, respectively. The DNA fragments were cloned into pGEX-4T vector. Recombinant plasmids transformed into Escherichia coli of BL21 pLysS (DE3) strain were induced to express GST or GST fused fragments of Nc-p43 such as 69 kDa protein for T, 66 kDa for S, 52 kDa for A, 53 kDa for P, and 40 kDa proteins for X, Y, and Z, respectively in SDS-PAGE. The Nc-p43 fragments of T, S, and P reacted with a bovine serum of neosporosis while those of A, X, Y, and Z together with GST did not in the western blot. These findings suggest that the antigenic domain of Nc-p43 of N. caninum may be localized in the C-terminal 2/3 parts. Together with A19 clone in SAG1 of Toxoplasma gondii (Nam et al., 1996), the P fragment of Nc-p43 could be used as efficient antigens to diagnose and differentiate those infections with both species.

Amino Acid Sequence↗

PubMed2000

Hypoglycemia-induced cerebellar dysfunction and quantitative positron emission tomography study.

OBJECTIVE: To describe an unusual case of hypoglycemia-induced bilateral cerebellar dysfunction. BACKGROUND: The cerebellum is known to be resistant to hypoglycemia, and selective cerebellar dysfunction caused by hypoglycemia has not been reported. Previous studies showed that the ratio between the rate constants for glucose uptake and phosphorylation (K1 and k3) is reversed in the cerebellum compared with the cerebral cortex; higher K1 in the cerebellum and higher k3 in the cerebral cortex. METHODS: Quantitative dynamic PET scanning with labeled fluorodeoxyglucose (18F-FDG) was performed to prove altered glucose kinetics in the cerebellum of a patient who presented with episodic cerebellar dysfunction associated with hypoglycemia. Four control subjects underwent the same study. RESULTS: The ratio between K1 and k3 was not reversed in the cerebellum of our patient (K1 = 0.082, k3 = 0.192). On the contrary, the ratio was reversed in the control subjects (mean K1 = 0.109, mean k3 = 0.080). In addition, the patient's cerebellar metabolic rate of glucose (rCMRglu = 27.9 micromol/100 g/minute) and the rate constant of glucose egress (k2 = 0.543) were relatively increased compared with those of control subjects (mean rCMRglu = 21.9 micromol/100 g/minute, mean k2 = 0.352). CONCLUSIONS: In a case of episodic bilateral cerebellar dysfunction caused by hypoglycemia, quantitative dynamic PET study demonstrated decreased glucose uptake-to-utilization ratio and increased leak of glucose in the cerebellum. The cerebellum is not invariably resistant to hypoglycemia.

Blood Glucose↗

PubMed2000

Cloning and characterization of the 5'-flanking region for the mouse phospholipase C-delta1 gene.

To date, little is known about the molecular mechanisms controlling the regulation of phospholipase C-delta1 (PLC-delta1) gene expression. To understand the mechanisms responsible for the regulation of PLC-delta1 gene expression, the 5'-flanking region of the mouse PLC-delta1 gene was isolated from a mouse genomic DNA library. Primer extension analysis revealed that there is a single transcriptional start site located at 127 bases upstream from the translation start codon in the mouse PLC-delta1 gene. DNA sequence analysis showed that the sequence around the transcriptional start site is very GC-rich and has no TATA or CAAT boxes. Transient expression of a luciferase reporter gene under the control of serially deleted 5'-flanking sequences revealed that the 160-base-pair region from -622 to -462 upstream of the transcriptional start site includes a positive cis-acting element(s) for the efficient expression of the PLC-delta1 gene. Gel retardation analysis suggests that multiple transcription factors bind to separate sites on the promoter region. Based on these results, our study suggests that the minimal essential region located at -622 to +70 is fully sufficient to confer high-level transcriptional activity and contains high-affinity binding elements for multiple transcription factors.

Animals↗

PubMed2000

The clinical usefulness of ictal surface EEG in neocortical epilepsy.

PURPOSE: Localizable scalp EEGs, during ictal episodes, appear to be rare in neocortical epileptic syndromes. However, studies based on large numbers of patients are also rare. This study aims to identify the characteristic patterns of variable neocortical epilepsies and to evaluate their clinical usefulness in the localization of epileptogenic focuses. METHODS: We retrospectively assessed 394 noninvasive ictal recordings from 86 patients who subsequently underwent invasive study and resective surgery. Ictal EEGs were recorded using a video-EEG monitoring system with electrodes placed according to the International 10-20 system, with additional anterior temporal electrodes. The ictal recordings were analyzed according to localizing accuracy and frequency characteristics. The durations of discrete or regional ictal rhythms were also measured. RESULTS: The percentage of discrete or regional EEGs was 23% in frontal lobe epilepsy, 52% in lateral temporal lobe epilepsy, 70% in occipital lobe epilepsy, and 10% in parietal lobe epilepsy. In order of frequency, the localizable ictal rhythms were theta, beta, alpha, delta, and rhythmic spike-and-wave. The duration of discrete or regional ictal rhythms was significantly shorter in frontal lobe epilepsy and parietal lobe epilepsy than in other epilepsies. Ictal beta activity was the most common rhythm in discrete-patterned EEGs. Structural lesions found on MRI did not significantly affect the localization of epileptogenic focuses in the patients. The type of seizure was not related to the degree of localization, with the exception of simple partial seizure. CONCLUSIONS: Ictal surface EEG was clinically helpful in the localization of epileptogenic focuses in at least some neocortical epileptic syndromes.

Adult↗

PubMed2000

A toxoplasmic uveitis case of a 60-year-old male in Korea.

A toxoplasmic uveitis case was reported on the focus of impairment of pathological findings and serological antibody titers after chemotherapy. A chief complaint of a 60-year-old male was a decreased and blurred vision in his right eye for 2 weeks after experiencing tremendous stress and fatigue. A steroid therapy for 3 weeks was not effective and the retinal lesion became necrotic. Anti-Toxoplasma gondii antibody titer was checked to be a strong positive by both ELISA and indirect latex agglutination assay (ILA). He was treated with Fansidar F for 8 weeks. His vision improved as the necrotic lesion healed by scarring, but the antibody titers still remained very high without any signs of negative conversion. It is suggested to be a recurrent case of the past asymptomatic infection by presumed immune suppression caused by excessive stress.

Animals↗

PubMed2000

Seroprevalence of toxoplasmosis in the residents of Cheju island, Korea.

This study was performed to evaluate the epidemiological status of toxoplasmosis among the residents of Cheju island. The sera of local students from 18 high schools (boys 2110, girls 2460) and those of adults (474 admitted to Cheju Chungang General Hospital) were collected and checked for the IgG antibody titers against Toxoplasma gondii. Serum samples collected from both the students and adults showed sero-positive rate of 5.5% and 12.9%, respectively. Although the rates were not significantly different between the sexes (5.4% for the boys and 5.5% for the girls attending school), the geographical difference showed a significant difference between the urban (4.6-6.9%) and rural areas (5.6-8.8%) (p < 0.05). Based on the high positive rates, it should be necessary to control toxoplasmosis in Cheju island.

Adolescent↗

PubMed2000

Detection of IgG antibody against Neospora caninum in cattle in Korea.

A total of 492 cattle sera was screened by IgG-ELISA against Neospora caninum (Nc-1 strain and a Korean isolate, KBA-2) and Toxoplasma gondii. Out of 492, 113 sera (23.0%) reacted positively to either Nc-1 or KBA-2 strains of N. caninum. Among the 113 positive sera, 92 sera (81.4%) reacted with antigens of both strains, but 6 sera (5.3%) with Nc-1 and 15 sera (13.3%) with KBA-2 strain only. And with T. gondii antigen, 6 sera (1.2%) were positive but all reacted with N. caninum antigen also. Western blot revealed typical binding pattern according to ELISA values, such that high OD group reacted specifically to the major surface proteins including 43 kDa protein. Seroprevalence of 23.0% indicates that neosporosis seemed to be one of major causes of abortion in cattle. It is suggested here to establish more epidemiological researches nationwide systematically.

Animals↗

PubMed1999

Evaluation of functional changes in the medial temporal region during intracarotid amobarbital procedure by use of SPECT.

PURPOSE: Because the main blood supply to the medial temporal region is through the posterior cerebral artery, the validity of the intracarotid amobarbital procedure (IAP) is still debated. To verify clinical validity of the IAP, we investigated changes in neuronal function in the medial temporal region during IAP. METHODS: Brain single photon emission computed tomography (SPECT) was performed during IAP (IAP-SPECT) in 22 patients with temporal lobe epilepsy (TLE), and regional cerebral blood flow (rCBF) in the medial and lateral temporal regions of interest (ROIs) was measured quantitatively. To determine the distribution of sodium amobarbital, in another 20 patients with TLE, SPECT images were obtained after intracarotid injection of 99mTc-HMPAO mixed with sodium amobarbital. RESULTS: Mean rCBF was 89.2% in the medial temporal region and 81.6% in the lateral temporal region: in the former region, it was significantly lower than that shown by the results of interictal SPECT (99.1%; p < 0.001). In a few patients, however, rCBF did not decrease in the medial temporal region. In only 25% of patients, the medial temporal region was visualized in SPECT images obtained after intracarotid injection of 99mTc-HMPAO. CONCLUSIONS: The results in this study demonstrate that IAP is valid because the medial temporal region is inactivated in spite of infrequent delivery of sodium amobarbital. We assume that intratemporal diaschisis is operating for the inactivation of neuronal function. IAP-SPECT with intratemporal ROIs may be useful for monitoring changes in neuronal function in the medial temporal region during IAP.

Adolescent↗

PubMed1999

A survey of helminthic infections in the residents of rural areas near Ulaanbaatar, Mongolia.

A total of 738 samples was collected to survey the helminthic infections of residents in two rural areas near Ulaanbaatar, Mongolia for 2 weeks from July 23 to August 2, 1998. Among 391 scotch-taped slides of anal swabs of children and of young teenagers. Enterobius vermicularis eggs were detected in 138 cases (35.3%). With the fecal samples of 206 Kato-Katz thick smear slides from adults, the eggs of E. vermicularis were observed in 9 cases and Taenia sp. in one case, respectively. And by ELISA on 141 blood samples absorbed to blood sampling paper, 12 cases (8.5%) were found to be positive against the hydatid cyst antigen. Enterobiasis and hydatidosis are two major endemic diseases which are related closely to the life style of Mongolian.

Adolescent↗

PubMed1999

Early recognized antigen (p34) of Toxoplasma gondii after peroral ingestion of tissue cyst forming strain (Me49 strain) in mice.

Serum from mouse orally ingested with tissue cyst forming strain (Me49) of Toxoplasma gondii was assayed by Western blot and immunofluorescene assay (IFA) to establish early responses in antigenicity of the parasite in mouse model of foodborne toxoplasmosis. Sera were collected weekly to blot the RH antigen transferred onto nitrocellulose paper after being separated by 12% SDS-PAGE. With the second week serum, 34 kDa protein (p34) was detected uniquely, and all antigens of T. gondii were detected with the sera from 3 or 4 weeks. p34 was not a member of the major surface membrane proteins and confirmed to be localized in the rhoptry by IFA. It was secreted into parasitophorous vacuolar membrane (PVM) during the entry into host cells. When applied to the human sera of which the ELISA absorbance was in negative range, 10.3% of sera detected p34, while all the ELISA positive sera detected the band. It has diagnostic usefulness of presumed T. gondii infection. We suggest the name of the p34 protein as ROP9.

Animals↗

PubMed1999

Western blot analysis of stray cat sera against Toxoplasma gondii and the diagnostic availability of monoclonal antibodies in sandwich-ELISA.

A total of 198 sera from stray cats was assayed against Toxoplasma gondii antigen by western blot. Out of 198 sera assayed, 26 sera (13.1%) showed typical blot patterns against T. gondii. When spotted by ELISA absorbance and indirect latex agglutination test (ILAT) titer, all 26 cases were distributed over the cut-off value of ELISA whereas 24 cases (92.3%) were in the positive range of 1:32 or higher and 2 cases in negative range by ILAT. Among western blot negative 172 sera, 162 cases were negative in both ILAT and ELISA while 10 cases were reactive falsely such that three cases were ILAT positive with 1:32 titer and 9 cases were ELISA positive (2 cases overlapped). These 10 cases reacted peculiarly without typical binding pattern in Western blot. Sandwich-ELISA was performed with monoclonal antibodies (mAbs) of Tg563 (30 kDa, SAG1), Tg505 (22 kDa, SAG2), Tg605 (43 kDa, SAG3), Tg556 (28 kDa. GRA2), Tg737 (32 kDa, GRA6), Tg695 (66 kDa, ROP2), Tg786 (42 kDa, ROP6), and Tg621 (32 kDa, anonymous but cytosolic) clone, respectively. All western blot-positive cases were in the positive range and negative cases in the negative range clearly. Among the 10 false reactive cases, 3 cases were in the positive range with one or more mAbs. All mAbs used in this study were confirmed to be specific to T. gondii infection as a standardized sandwich-ELISA to differentiate it from other pathogens.

Animals↗

PubMed1998

Changes in enzyme activity and expression of DHFR of Toxoplasma gondii by antifolates.

The responses to antifolates of Toxoplasma gondii were investigated by measuring the dihydrofolate reductase (DHFR) activity, quantity of DHFR mRNA, and single-strand conformational polymorphism (SSCP) pattern. Pyrimethamine (PYM) and methotrexate (MTX) were tested as antifolates. When T. gondii was treated with PYM, the viability was decreased by the increasing concentration of PYM, DHFR activity tended to increase as the passage proceeded, and the quantity of mRNA expressed was also increased according to passages. The viability of T. gondii was decreased by the increasing concentration of MTX, but it was maintained over 40% up to 100 microM MTX. DHFR activity was 77.4% in the 1st passage (1 microM). 82.2% in the 4th passage (10 microM), and 141.3% in the 7th passage (100 microM). But no changes were detected in SSCP pattern of T. gondii exposed to PYM and MTX, both. These results suggested that the response of T. gondii to PYM was regulated by transcriptional level and that, in MTX, the viability of T. gondii was derived from increasing DHFR activity.

Animals↗