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S C Lee

Publications and source records attributed to S C Lee.

At least 19 recordsLinked to original sources
PubMed1992

Primary structure, chromosomal localization, and functional expression of a voltage-gated sodium channel from human brain.

A cDNA library derived from human cerebral cortex was screened for the presence of sodium channel alpha subunit-specific clones. Ligation of three overlapping clones generated a full-length cDNA clone, HBA, that provided the complete nucleotide sequence coding for a protein of 2005 amino acids. The predicted structure suggests four homologous repeats and exhibits greatest homology and structural similarity to the rat brain sodium channel II. A second cDNA clone, HBB, that encodes a different subtype of sodium channel was isolated. Hybridization of DNA fragments from the 3' untranslated region of HBA and PCR with primers derived from HBB with human-hamster somatic cell hybrids localized these clones to human chromosome 2. In situ hybridization to human metaphase chromosomes mapped the structural genes for both HBA and HBB sodium channels to chromosome 2q23-24.3. The sodium channel HBA gene product was expressed by transfection in CHO cells. Expressed HBA currents were voltage-dependent, sodium-selective, and tetrodotoxin-sensitive and, thus, exhibit the biophysical and pharmacological properties characteristic of sodium channels.

Amino Acid Sequence↗
PubMed1992

Glutamate differentially inhibits the expression of class II MHC antigens on astrocytes and microglia.

MHC molecules are required for Ag recognition by T cells. Inasmuch as cells in the central nervous system do not express MHC constitutively, appearance of MHC, in inflammatory and degenerative diseases of the brain, may indicate local Ag presentation and subsequent immune response. Although both astrocytes and microglia are capable of class II MHC expression in vitro, in vivo studies failed to show the presence of significant amounts of class II on astrocytes compared to microglia. Our study is designed to clarify possible regulatory mechanisms that can explain the differences in inducibility of class II MHC between astrocytes and microglia in vivo. Using dissociated rat brain cell cultures, we have found that glutamate, an excitatory neurotransmitter, exerted a profound inhibitory effect on IFN-gamma-induced expression of class II on astrocytes, but not on microglia. Both glutamate and norepinephrine, a neurotransmitter previously reported to down-regulate class II on astrocytes, inhibited the induction of class II on astrocytes by eliminating accumulation of class II MHC mRNA. The kinetics of class II mRNA induction by IFN-gamma in the presence of glutamate suggested that glutamate may act as a transcriptional inhibitor. It is likely that class II induction on astrocytes in vivo may be selectively down-regulated by neurotransmitters such as glutamate and norepinephrine.

Animals↗
PubMed1992

The effect of pepsin digestion in relation to the pre-S region on hepatitis B surface antigen-induced hypersensitivity.

The role of the pre-S region of the hepatitis B surface Ag (HBsAg) particle in hypersensitivity to HBsAg was evaluated in mice. Plasma-derived or recombinant HBsAg was digested with pepsin to prepare different forms of HBsAg with or without pre-S region. Strains of mice including AKR/J (H-2k), A.SW (H-2s), C3H/He (H-2k), and CBA/J (H-2k) did not respond to the major S protein with regard to hypersensitivity. However, the pre-S-containing HBsAg overcame this nonresponsiveness. In BALB/c (H-2d) and A/J (H-2a) mice, the pre-S-containing HBsAg induced higher hypersensitivity than did the major S protein. The enhancement induced by the pre-S region was demonstrated to occur during the induction phase by crisscross assay using pre-S-containing HBsAg and major S protein as Ag. The patterns of hypersensitivity induced by the major S, middle S (composed of major S and pre-S2), and large S (composed of middle S and pre-S1 proteins) were also compared. The middle S protein induced responses of 1-h and 24-h hypersensitivities in major S non-responder (C3H/He and CBA/J) mice, whereas the large S protein circumvented only the 1-h one. The effectiveness to stimulate hypersensitivities in vivo by HBsAg is in the following order: middle S greater than large S greater than major S. These data suggest that the pre-S region of HBsAg particle can enhance both the 1-h and 24-h hypersensitivities in the afferent phase.

Animals↗
PubMed1992

Effect of overproduction of heat shock chaperones GroESL and DnaK on human procollagenase production in Escherichia coli.

The effect of overexpression of the heat shock chaperone genes dnaK and groESL on heterologous protein production in Escherichia coli was examined, using a set of related human procollagenase proteins. A diverse range of effects on protein solubility, secretion, and accumulation was observed, and these effects were highly dependent on the particular chaperone/procollagenase pairing involved. Both chaperones caused a large increase in the apparent solubility of a fusion of the LamB signal peptide to procollagenase. GroESL had no effect on the accumulation of mature (secreted) procollagenase, while DnaK suppressed secretion considerably. In the absence of a signal peptide, overexpression of either chaperone resulted in a dramatic increase in both solubility and accumulation of procollagenase. The 10-fold increase in accumulation was associated with an increase in in vivo protein half-life.

Bacterial Outer Membrane Proteins↗
PubMed1992

Extraction of penicillin G from simulated media by an emulsion liquid membrane process.

The extraction of penicillin G from simulated media was performed by water/oil/water (w/o/w) emulsion liquid membranes (ELMs) and studied under various operational conditions in a batch system. The degree of extraction achieved was between 80% and 95% under specific conditions. A concentration of greater than nine times the initial concentration of penicillin G in the external phase was obtained in the internal phase. The pH of the internal aqueous solution, containing a basic salt, was theoretically calculated on the basis of the amount of penicillin G transported into the internal phase. The calculated results agreed with the experimental data well and were used to select a suitable type and concentration of a basic salt in the internal phase to give a pH within the range 5 to 8 where penicillin G was stable after the termination of extraction. The extraction of penicillin G was successfully performed by the ELM process with sodium carbonate in the internal phase.

Biotechnology↗
PubMed1992

Genetic polymorphism and activities of human lung alcohol and aldehyde dehydrogenases: implications for ethanol metabolism and cytotoxicity.

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) exhibit genetic polymorphism and tissue specificity. ADH and ALDH isozyme phenotypes from 39 surgical Chinese lung specimens were identified by agarose isoelectric focusing. The identity of the lung beta-ADHs was further demonstrated by their characteristic pH-activity profiles for ethanol oxidation, Km values for NAD and ethanol, and inhibition by 4-methylpyrazole or 1,10-phenanthroline. The beta 2 allele, coding for beta 2 polypeptide, was found to be predominant in the lung specimens studied. The ADH activities in the lungs with the homozygous phenotype ADH2 2-2 (exhibiting beta 2 beta 2) and ADH2 1-1 (exhibiting beta 1 beta 1) and the heterozygous phenotype ADH2 2-1 (exhibiting beta 2 beta 2, beta 2 beta 1, and beta 1 beta 1) were determined to be 999 +/- 77, 48 +/- 17, and 494 +/- 61 nmol/min/g tissue, respectively. Fifty-one percent of the specimens studied lacked the ALDH2 activity band on the isoelectric focusing gels. The activities in the lung tissues with the ALDH2-active phenotype and the inactive phenotype were determined to be 30 +/- 3 and 17 +/- 1 nmol/min/g tissue, respectively. These findings indicate that human pulmonary ethanol-metabolizing activities differ significantly with respect to genetic polymorphism at both the ADH2 and the ALDH2 loci. The results suggest that individuals with high Vmax beta 2-ADH and deficient in low-Km mitochondrial ALDH2, accounting for approximately 45% of the Chinese population, may end up with acetaldehyde accumulation during alcohol consumption, rendering them vulnerable to tissue injury caused by this highly reactive and toxic metabolite.

Adult↗
PubMed1992

Correlation of plasma cytokine elevations with mortality rate in children with sepsis.

Cytokines are thought to be important endogenous mediators of the host immune response to bacterial infection. We hypothesized that plasma levels of cytokines are elevated in children with sepsis and that the magnitude of elevation of these cytokines is correlated with severity of illness and mortality rate. We determined plasma levels of tumor necrosis factor, interleukin-6, and interleukin-1 in 21 children with sepsis. Plasma samples were collected at presentation and at 12, 24, and 48 hours thereafter. Cytokine levels were elevated in pediatric patients with bacterial sepsis during the first 48 hours after presentation; levels were undetectable in study control subjects. The tumor necrosis factor and interleukin-6 levels (p less than 0.001), as well as levels of interleukin-1 (p = 0.05), were significantly higher in nonsurvivors than in survivors and were independent of severity of illness (pediatric risk of mortality (PRISM) score) at presentation. Elevations of tumor necrosis factor and interleukin-6 were sustained for longer than 24 to 48 hours in nonsurvivors: II-1 concentrations were significantly increased only at time zero. Of 11 children with an interleukin-6 value greater than 2 ng/ml during the first 48 hours, 10 died; only one of 10 not reaching that level died (p less than 0.001). Cytokines were elevated as frequently with gram-positive as with gram-negative infections. We speculate that cytokine determinations may identify children who might benefit from immunotherapeutic interventions.

Adolescent↗
PubMed1992

Diverse K+ channels in primary human T lymphocytes.

We used patch clamp techniques to identify and characterize a variety of K+ channels in primary human peripheral T lymphocytes. The most common channel observed in cell-attached configuration was voltage gated and inactivating. In ensemble averages, the kinetics of its activation and inactivation were similar to those of the whole-cell, voltage-gated K+ current described previously (Cahalan, M. D., K. G. Chandy, T. E. DeCoursey, and S. Gupta. 1985. J. Physiol. [Lond.]. 358:197-237; Deutsch, C., D. Krause, and S. C. Lee. 1986. J. Physiol. [Lond.]. 372:405-423), suggesting that this channel underlies the major portion of the outward current in lymphocytes. A small fraction of the time, this or another very similar channel was observed to inactivate significantly more slowly. Another channel type observed in cell-attached recording was seen less frequently and was transient in its appearance. This channel has a unitary conductance of approximately 10 pS, similar to the voltage-gated channel, but its voltage-independent gating, lack of inactivation, and different kinetic parameters showed it to be distinct. In whole-cell recording there is often a significant plateau current during sustained depolarization. Experiments using whole-cell and excised outside-out configurations indicate that at least part of this residual current is carried by K+ and, as opposed to the predominant voltage-gated current, is charybdotoxin insensitive. These findings are consistent with evidence that implicates charybdotoxin-sensitive and -insensitive components in T lymphocyte proliferation and volume regulation.

Adult↗
PubMed1992

Structure and expression of mouse alpha 1-acid glycoprotein gene-3 (AGP-3).

The genome of Mus domesticus has multiple genes of the alpha 1-acid glycoprotein (AGP). Two cDNA clones were identified corresponding to AGP-1 and AGP-2. Moreover, two alleles of AGP-1 exist in inbred mice. The genomic DNA of the AGP-2 gene has been cloned and studied. Here we report the genomic organization of three M. domesticus AGP genes, the sequence analysis of the AGP-3 genomic DNA, and the expression of the AGP-3 gene. The major structural differences between AGP-2 and AGP-3 genes are located in introns 1 and 5. The low level of AGP-3 mRNA can be detected by the polymerase chain reaction (PCR). The molecular basis of the low level expression of AGP-3 and the possible classification of AGP-3 as a pseudogene are discussed.

Amino Acid Sequence↗
PubMed1992

Hypoxic preconditioning of ischaemic canine myocardium.

OBJECTIVE: The aim was to test whether a brief period of non-ischaemic hypoxia can precondition myocardium. METHODS: 60 anaesthetised adult mongrel dogs of either sex underwent 60 min occlusion of the left anterior descending coronary artery, followed by 5 h reperfusion. In treated groups, hearts were either preconditioned with 5 min coronary perfusion with hypoxic blood [O2 content 9.2(SEM 0.6) ml.litre-1] or 5 min occlusion followed by a 10 min reperfusion period prior to 60 min occlusion. The effect of these treatments on myocardial infarct size and regional contractile function was assessed. RESULTS: Infarct size, determined by tetrazolium staining, as a percentage of anatomical area at risk was markedly decreased in hypoxia preconditioned hearts, at 7.2(1.8)% v 22.4(4.6)% in controls (p < 0.01), but did not differ from ischaemia preconditioned hearts [4.6(1.7)%; p < 0.01 v control]. Anatomical area at risk, expressed as a percentage of left ventricular mass, and collateral blood flow to the inner two thirds of the ischaemic wall did not differ among the groups. Regional contractile function was depressed following ischaemic preconditioning but not following hypoxic preconditioning. During reperfusion following 60 min occlusion, marked paradoxical systolic lengthening was evident in ischaemia preconditioned and control hearts but not in hypoxia preconditioned myocardium. CONCLUSIONS: Five minutes of hypoxic and ischaemic preconditioning were equipotent in preventing infarction, whereas ischaemic preconditioning caused a greater decrement in postischaemic contractile function.

Animals↗
PubMed1992

Canine coronary vasodepressor responses to hypoxia are attenuated but not abolished by 8-phenyltheophylline.

The purpose of this study was twofold: 1) to verify a report that a suspension of 8-phenyltheophylline (8-PT) completely abolished hypoxia-induced coronary vasodilation [H. M. Wei, Y. H. Kang, and G. F. Merrill. Am. J. Physiol. 257 (Heart Circ. Physiol. 26): H1043-H1048, 1989] and 2) to determine the effect of dissolved 8-PT on hypoxic hyperemia. The left anterior descending coronary artery of anesthetized dogs was cannulated and perfused at either constant flow or constant pressure. An 8-PT suspension (40 micrograms.kg-1.min-1) produced a twofold elevation of coronary perfusion pressure at constant flow, a 97% decrease in coronary flow at constant pressure, and regional akinesia in both conditions. The coronary vasculature was unresponsive to 60-s coronary occlusion, exogenous adenosine, and hypoxia after infusion of the 8-PT suspension. These findings are consistent with obstruction of the coronary microvasculature by the 8-PT suspension. An 8-PT solution (40 micrograms.kg-1.min-1) produced 95 +/- 3% (P less than 0.001, n = 6) attenuation of exogenous adenosine-induced vasodilation at constant pressure, a 28 +/- 5% (P less than 0.01, n = 6) attenuation of reactive hyperemia, and a 24 +/- 6% (P less than 0.05, n = 6) decrease in hypoxia-induced vasodilation. An 8-PT solution had no effect on systolic segment length shortening and myocardial oxygen consumption. We conclude that 8-PT, when in solution, attenuates but does not abolish the coronary vasodilatory response to hypoxia. Hence, adenosine appears to contribute to hypoxia-induced vasodilation but is not uniquely responsible for the hyperemic response.

Adenosine↗
PubMed1992

Transcranial Doppler assessment of cerebral flow velocity during cognitive tasks.

BACKGROUND AND PURPOSE: The purpose of this study was to assess the ability of transcranial Doppler ultrasonography to detect selective circulatory changes during cognitive activity. METHODS: We measured cerebral artery flow velocity in 21 normal volunteers by transcranial Doppler ultrasonography during rest followed by cerebral activation. Mean and peak systolic flow velocities of the anterior, middle, and posterior cerebral arteries were measured during the performance of a commercial video game. We also measured flow velocity of the anterior cerebral arteries in 18 subjects during a mental arithmetic task. Serial measurements of the right and left sides were made with a headband with two probes. RESULTS: We observed a global increase in the flow velocity above baseline measurements during task performance. During the video game, both middle cerebral arteries (t = 2.6, p = 0.02 for the left; t = 3.3, p = 0.004 for the right) and the left posterior cerebral artery (t = 2.2, p = 0.004) had selective increase in mean flow velocity compared with the ipsilateral anterior cerebral artery. This selective activation was most prominent in the right middle cerebral artery, which had a greater degree of activation than the right posterior cerebral artery (t = 2.8, p = 0.013). We did not observe a statistically significant difference between the right and left middle cerebral arteries, but there was a trend toward a greater activation on the right for both the mean velocity (t = 1.7, p = 0.098) and the peak velocity (t = 1.9, p = 0.079). CONCLUSIONS: Our preliminary investigation suggests that this noninvasive technique has the potential to correlate selective cerebral artery flow dynamics with cognitive activity.

Adolescent↗
PubMed1992

Portal and superior mesenteric venous gas with retroperitoneal abscess--CT diagnosis (case report).

We present a case of portal and superior mesenteric venous gas in a 31-year-old diabetic woman with a left-sided retroperitoneal abscess. Five years prior to admission, patient was diagnosed with diabetes mellitus and developed emphysematous pyelonephritis, requiring nephrectomy on the left side. A CT examination showed air distributed throughout the portal venous system and superior mesenteric vein.

Abscess↗
PubMed1992

Incidence estimation of genitourinary cancer in Korea.

A nation-wide study was performed to estimate the incidence of bladder, kidney, renal pelvis and ureter, prostate, testicular and other genitourinary cancer among Koreans in Korea using medical records of the inpatients of the beneficiaries of the Korea Medical Insurance Corporation (KMIC) from Jan. 1, 1989 to Dec. 31, 1989. The crude incidence rate of bladder cancer (ICD-9 188) is estimated to be 4.43 and 0.98 per 100,000 in males and females, respectively. Around 1,093 new cases of bladder cancer (895 male and 198 female) are estimated to occur in a year. The adjusted rate for the world population is 7.76 in males and 1.19 in females which is similar to that of Japanese in Osaka and Chinese in Shanghai, but lower than in American whites and blacks. The crude incidence of kidney, renal pelvis and ureteral cancer (ICD-9 189) is estimated to be 1.61 and 0.87 in males and females, respectively. Around 507 new cases of kidney, renal pelvis and ureteral cancer (332 male and 175 female) are estimated to occur in a year. The adjusted rate for the world population is 2.69 in males and 1.04 in females. In the prostate (ICD-9 185), the crude incidence rate of cancer is estimated to be 1.36. Around 274 new cases of prostate cancer are occurring in a year. The adjusted rate for the world population is 2.98 which is similar to the Chinese rate. The incidence of genitourinary cancer continuously increases with age.

Adult↗
PubMed1992

Locomotor strategies before independent walking: prospective study of 50 mentally retarded children.

To investigate the association between pre-walking locomotor strategies and psychomotor developments in children with mental retardation (MR), 50 children with non-specific MR were included in this study. There were 29 boys and 21 girls, 96% of whom had moderate to severe MR. They were followed from 4-53 months to 25-99 months of age, and their follow-up periods ranged from 10 to 48 months (mean 30 months). According to the pre-walking locomotor strategies, these children were categorized into three groups: the crawling group (n = 34) who used crawling or creeping as their main locomotion pattern before independent walking; the shuffling group (n = 9) who used shuffling prior to independent walking; and the direct-walking group (n = 7) who did not have any other locomotor strategies except rolling. In almost all motor developmental milestones, children in the direct-walking group developed earlier than those in the crawling and shuffling groups. Children in the crawling group had more advanced developments than those in the shuffling group. The difference in the mean ratio developmental quotients of the Bayley Mental Scale among the three groups was not significant. The present study showed that crawling may not be a necessary prerequisite for early ambulation or better cognitive function in MR children.

Child Development↗
PubMed1992

Specific restriction fragment length polymorphism in liver mitochondrial DNA of the Chinese.

By use of restriction fragment length polymorphism analysis, we examined the liver mitochondrial DNA amplified by polymerase chain reaction from 60 Chinese subjects of 31 to 78 years of age. We found nine specific mtDNA polymorphisms that had never been reported before. Eleven subjects had an Alu I polymorphic site in the subunit 2 gene of NADH dehydrogenase, five had a Hae III polymorphic site in the cytochrome oxidase subunit 2 gene, and five had a Hinf I polymorphic site in the subunit 3 gene of cytochrome oxidase. No polymorphic site was found in the structural genes coding for subunits 1, 3, 4, 4L and 6 of NADH dehydrogenase, cytochrome b, and subunit 8 of ATP synthase. Detailed analysis of the RFLP data did not show age-dependent mtDNA polymorphisms. In addition, the analysis of the restriction patterns of all the mtDNAs revealed 12 mtDNA haplotypes in all the Chinese subjects examined. Among them, type 1 mtDNA was found to be the most predominant and comprised 63.3% of the total study subjects. The restriction patterns of type 1 mtDNA generated by all restriction enzymes were identical to those deduced from the Cambridge sequence of human mtDNA. About 8.3% of the subjects exhibited type 2 mtDNA, and 5% had types 3, 5 and 8 mtDNA, respectively. Each of the rest seven mtDNA types comprised about 2% of the samples. Moreover, type 1 mtDNA was found in the platelets of three white Americans. These findings suggest that type 2 to type 12 mtDNAs have come into existence through the generation or loss of specific polymorphic restriction sites in the mtDNA of the Chinese.

Adult↗
PubMed1992

Characterization of primary human fetal dissociated central nervous system cultures with an emphasis on microglia.

BACKGROUND: We undertook a systematic examination of human fetal central nervous system dissociated cell cultures, particularly with respect to microglia and their dynamic interactions with other central nervous system cell components. EXPERIMENTAL DESIGN: The growth and differentiation of astrocytes, microglia, and small immature neuronal cells in mixed and single cell type-enriched cultures were followed by phase contrast microscopy, immunocytochemistry, flow cytometry, electron microscopy and immunoelectron microscopy, in regard to their phenotype change, proliferation and class II major histocompatibility complex antigen expression. RESULTS: Both astrocytes and microglia expressed marked phenotype heterogeneity, but they were consistently positive for glial fibrillary acidic protein and CD68, respectively. Highly enriched astrocyte and microglial cultures suitable for biochemical or molecular biologic studies were obtained. Using double immunocytochemical labeling techniques with the proliferating cell nuclear antigen and cell-type specific markers, astrocytes grown in serum-containing media showed a high labeling index, whereas microglia seldom exhibited a similar degree of proliferative activity. Microglia, however, proliferated in response to certain growth factors, such as granulocyte macrophage colony-stimulating factor. Both microglia and astrocytes expressed high basal levels of class II MHC antigens, which further increased with addition of interferon-gamma. The microglia in dissociated cultures existed in two forms, ameboid and ramified. Microglial ramification was induced when ameboid microglia were co-cultured with a monolayer of astrocytes, suggesting a role for astrocytes in microglial differentiation. In addition, lipopolysaccharide in nanogram amounts consistently enhanced microglial survival and morphologic differentiation. The small bipolar cells, the most frequent cell type in mixed culture, were glial fibrillary acidic protein (-) and CD68 (-), and their size and shape remained unchanged under our culture conditions. A subpopulation of small bipolar cells was stained positive with an antibody to surface ganglioside, A2B5. Electron microscopic examination showed that their processes contained parallel microtubules bearing side arms consistent with immature neurons. CONCLUSIONS: Highly purified astrocyte and microglial cultures are obtained using the currently described technique. The current culture system is a valuable tool in studying human central nervous system biology and disease.

Astrocytes↗