Biomedical subjects

Sanghyun Lee

Publications and source records attributed to Sanghyun Lee.

At least 19 recordsLinked to original sources

PubMed2026

IgA is necessary and sufficient to prevent norovirus infection in mice.

Human norovirus is the leading cause of viral gastroenteritis, yet effective vaccines and therapeutics remain elusive. Using murine norovirus as a model, we found that mucosal immunoglobulin A (IgA) is both necessary and sufficient for protection against infection, whereas CD8+ T cells are dispensable. Robust intestinal IgA production requires at least 4 weeks of enteric infection, consistent with kinetics of human norovirus RNA clearance. Systemic vaccination elicits high titers of neutralizing serum IgG but fails to prevent enteric norovirus infection, phenocopying a recent human norovirus vaccine failure. In contrast, prophylactic delivery of dimeric anti-norovirus IgA via mRNA lipid nanoparticles confers sterilizing immunity. Together, these findings define a critical role for mucosal IgA in norovirus protection and identify IgA-based treatments as a therapeutic approach for human norovirus.

Animals↗

PubMed2007

Protective effect of (4-methoxybenzylidene)-(3-methoxynophenyl)amine against neuronal cell death induced by oxygen and glucose deprivation in rat organotypic hippocampal slice culture.

Resveratrol (trans-3,4',5-trihydroxystilbene) is a natural phytoalexin found in grape skin, and has been suggested to be an antioxidant agent, an anticancer agent and a cardioprotective agent. In particular, recent experimental evidence has demonstrated that resveratrol exhibits neuroprotective effects in various assay systems. During the study on the resveratrol derivatives, we found that (4-methoxybenzylidene)-(3-methoxyphenyl)amine (MBMPA), which has blocked free phenolic groups, strongly protects neuronal cells against ischemic damage on a higher activity than resveratrol. The MBMPA potently reduced the level of neuronal cell death in an oxygen and glucose deprivation-exposed rat organotypic hippocampal slice culture. In addition, ATP depletion following the onset of oxygen and glucose deprivation in an adult hippocampal slice was blocked by the MBMPA treatment. These results suggest that MBMPA has a neuroprotective effect on an in vitro ischemia model, and may be useful for treating stroke.

Adenosine Triphosphate↗

PubMed2006

Proteomic analysis of cellular change involved in mitochondria-to-nucleus communication in L6 GLUT4myc myocytes.

Genetic or biochemical abnormalities in mitochondria are closely associated with apoptosis, aging, cancer, and other chronic degenerative diseases. Mitochondrial dysfunction resulting from mitochondrial DNA (mtDNA) depletion dispatches retrograde signals to the nucleus to compensate by altering the expression of various genes. In this study, a proteomic approach was used to gain insight into the nuclear gene targets of mitochondrial stress signaling and the pathophysiological mechanisms associated with mitochondrial dysfunction. We have used 2-DE to characterize the nuclear gene responses resulting from mtDNA depletion in L6 GLUT4myc myocytes. Our results showed that 77 polypeptides were differentially expressed in mtDNA-depleted cells; 33 polypeptides were down-regulated and 44 polypeptides were up-regulated. Of these differentially expressed polypeptides, 40 were identified as 36 different proteins by MALDI-TOF MS. These proteins are related to various cellular responses, such as apoptosis, cellular metabolism, signaling and cytoskeleton functions. It is suggested that the insulin resistance developed in mtDNA-depleted myocytes may be associated with disorganization of cytoskeleton assembly, and that cellular mtDNA depletion might promote the ability to evade apoptosis or other death effectors.

Animals↗

PubMed2006

Anti-obesity effect of Pinellia ternata extract in Zucker rats.

Pinellia ternata is known as the herb effective in removing dampness-phlegm, one of the causes of obesity in traditional Korean medicine. Pinellia ternata water extract (PE) was fed to rats after mixing with diet once a day (400 mg x kg(-1)) for 6 weeks. We investigated its effect on the thermogenesis and fatty acids oxidation with obese Zucker rats. We also determined the gene expression of uncoupling protein 1 (UCP1), peroxisome proliferators-activated receptor alpha (PPARalpha), and PPARgamma coactivator 1alpha (PGC1alpha). The PE treatment lowered the levels of triglyceride and free fatty acids (p<0.05) in blood of the obese rats and the body weight was also reduced slightly. It was also observed that PE significantly increased the expression of both UCP1 mRNA in brown adipose tissue (BAT) (p<0.001) and PPARalpha and PGC1alpha mRNA in white visceral adipose tissue (WAT) (p<0.05 and p<0.001, respectively), which may cause a reduction of obesity. These results suggested that PE would be able to affect anti-obesity through thermogenesis and fatty acid oxidation.

Animals↗

PubMed2006

Geniposide from Gardenia jasminoides attenuates neuronal cell death in oxygen and glucose deprivation-exposed rat hippocampal slice culture.

Geniposide from Gardenia jasminoides protected neuronal cells from damage in oxygen and glucose deprivation-exposed hippocampal slice culture. Geniposide showed a greater protective effect on the granule cell layer than on the pyramidal cell layer including CA 1 and CA 3. On the basis of the experimental results, geniposide may be a therapeutic agent for ischemia in patients.

Animals↗

PubMed2005

Lignans from Acanthopanax chiisanensis having an inhibitory activity on prostaglandin E2 production.

The chloroform and the ethyl acetate fractions from the roots of Acanthopanax chiisanensis exhibited the significant inhibition of TPA-induced prostaglandin E(2) (PGE(2)) production in rat peritoneal macrophages. Five lignans were isolated from the chloroform fraction and their structures were elucidated as l-sesamin, helioxanthin, savinin, taiwanin C, and 3-(3,4-dimethoxybenzyl)-2-(3,4-methylenedioxybenzyl)butyrolactone. Among the lignans tested, taiwanin C showed the most potent inhibitory activity (IC(50) = 0.12 microM) on PGE(2) production with the relative order of potency, taiwanin C >> 3-(3,4-dimethoxybenzyl)-2-(3,4-methylenedioxybenzyl)butyrolactone > savinin = helioxanthin. l-Sesamin showed no inhibitory activity at 30 microM.

Animals↗

PubMed2005

Inhibitory effects of Ganoderma applanatum on rat lens aldose reductase and sorbitol accumulation in streptozotocin-induced diabetic rat tissues.

Aldose reductase, the key enzyme of the polyol pathway, is known to play important roles in diabetic complications. Therefore, inhibitors of aldose reductase would be potential agents for the prevention of diabetic complications. To evaluate the inhibitory potential of aldose reductase from Ganoderma applanatum (Polyporaceae), methanol (MeOH) and water extracts were tested for their effects on rat lens aldose reductase (RLAR). The effects of both extracts on streptozotocin (STZ)-induced diabetes in rats were also investigated. The MeOH extract exhibited a potent rat lens aldose reductase (RLAR) inhibition in vitro, and showed a significant inhibition, of not only serum glucose concentrations, but also of sorbitol accumulations in the lens, red blood cells (RBC) and sciatic nerves in STZ-induced diabetic rats. Associated with a reduction in serum glucose concentration in STZ-induced diabetic rats, this extract was found to cause a significant glucose tolerance effect. These results suggested that G. applanatum might possess constituents with antidiabetic and inhibitory effects on diabetic complications.

Aldehyde Reductase↗

PubMed2005

Anti-estrogenic activity of lignans from Acanthopanax chiisanensis root.

Anti-estrogenic activity of (-)-sesamin (1), helioxanthin (2), savinin (3), taiwanin C (4), and 3-(3,4-dimethoxybenzyl)-2-(3,4-methylenedioxybenzyl)butyrolactone (5) isolated from the root of Acanthopanax chiisanensis was tested using Ishikawa cells. Among them, compound 3 exhibited anti-estrogenic activity (IC50 = 4.86 microM).

Adenosine Triphosphatases↗

PubMed2005

Two new non-glycosidic iridoids from the leaves of Campsis grandiflora.

Two new non-glycosidic iridoids, which were named cachinol (1) and 1-O-methyl cachinol (2), were isolated from the methanol extract of the leaves of Campsis grandiflora together with a known iridoid cachineside I (3). The structures of compounds 1 and 2 were determined on the basis of spectroscopic methods including two dimensional NMR and high resolution mass spectrometry. All of the isolated compounds showed mild inhibitory activities on rat platelet aggregation. Compounds 1 and 3 (IC50 : 246 and 219 microM, respectively) showed about 2-fold higher inhibitory effects than acetylsalicylic acid (ASA, IC50: 412 microM) on collagen-induced aggregation. Compounds 1 and 2 (IC50: 43.2 and 38.4 microM, respectively) were about 2-fold more inhibitory than ASA (IC50: 75.2 microM), and about 4-fold more effective than their glycoside 3 (IC50: 189 microM) on AA-induced aggregation.

Animals↗

PubMed2005

Aldose reductase inhibitors from the fruiting bodies of Ganoderma applanatum.

The isolation and characterization of rat lens aldose reductase (RLAR) inhibitors from the fruiting bodies of Ganoderma applanatum were conducted. Among the extracts and fractions from G. applanatum tested, the MeOH extract and EtOAc fraction were found to exhibit potent RLAR inhibition in vitro, their IC50 being 1.7 and 0.8 microg/ml, respectively. From the active EtOAc fraction, seven compounds with diverse structural moieties were isolated and identified as D-mannitol (1), 2-methoxyfatty acids (2), cerebrosides (3), daucosterol (4), 2,5-dihydroxyacetophenone (5), 2,5-dihydroxybenzoic acid (6), and protocatechualdehyde (7). Among them, protocatechualdehyde (7) was found to be the most potent RLAR inhibitor (IC50=0.7 microg/ml), and may be useful for the prevention and/or treatment of diabetic complications.

Aldehyde Reductase↗

PubMed2005

Inhibitory effects of isorhamnetin-3-O-beta-D-glucoside from Salicornia herbacea on rat lens aldose reductase and sorbitol accumulation in streptozotocin-induced diabetic rat tissues.

The inhibitory effects of compounds from Salicornia herbacea (Chenopodiaceae) on rat lens aldose reductase (RLAR) and sorbitol accumulation in streptozotocin-induced diabetic rat tissues were investigated. The various fractions from the MeOH extract of S. herbacea were tested for their effects on RLAR in vitro. Among them, the EtOAc fraction was found to exhibit a potent RLAR inhibition (IC(50)=0.75 microg/ml), from which an active principle as a potent AR inhibitor was isolated and its chemical structure was elucidated as isorhamnetin-3-O-beta-D-glucoside (1) by spectral analysis. Compound 1 exhibited a potent RLAR inhibition in vitro, its IC(50) being 1.4 microM. Compound 1, when administered orally at 25 mg/kg in streptozotocin (STZ)-induced diabetic rats, caused not only a significant inhibition of serum glucose concentration but also sorbitol accumulation in the lenses, red blood cells (RBC), and sciatic nerves. These results indicate that compound 1 from S. herbacea is a leading compound for further study as a new drug for the prevention and/or treatment of diabetes and its complications.

Aldehyde Reductase↗

PubMed2005

Relations among measures of trait empathy, empathetic response, and willingness to get involved in customer-contact situations.

This study examined anticipated reactions to nonroutine occurrences in the context of emotionally laden customer-contact situations in retail stores. Correlations between measures of the dimensions of trait empathy, anticipated emotional responses to the situations, and self-rated willingness to be involved were examined. Anticipated Compassion mediated the relation of Empathetic Concern on Involvement Willingness in 3 of 4 imaginary compassion-evoking situations. No corresponding effect was observed for Anticipated Distress in the imaginary distress-evoking situations.

Adult↗

PubMed2004

Inhibition of lipopolysaccharide-induced expression of inducible nitric oxide synthase and tumor necrosis factor-alpha by 2'-hydroxychalcone derivatives in RAW 264.7 cells.

In cultures of the murine macrophage cell line RAW 264.7, effects of four 2'-hydroxychalcone derivatives, 2'-hydroxy-4'-methoxychalcone (compound 1), 2',4-dihydroxy-4'-methoxychalcone (compound 2), 2',4-dihydroxy-6'-methoxychalcone (compound 3) and 2'-hydroxy-4,4'-dimethoxychalcone (compound 4), on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and tumor necrosis factor (TNF)-alpha were examined. Compounds 1, 2 and 3 at 3-30microM inhibited the production with almost the same potency. Compound 4 showed no inhibitory activity. Compounds 1, 2 and 3 at 3-30microM inhibited the LPS-induced expression of inducible nitric oxide synthase (iNOS) and TNF-alpha mRNA. To clarify the mechanism involved, effects of compounds 1, 2 and 3 on the activation of nuclear factor (NF)-kappaB and activator protein-1 (AP-1) were examined. Both the LPS-induced activation of NF-kappaB and AP-1 were blocked by compounds 1, 2 and 3 at 3-30microM. Moreover, the three compounds at such concentrations inhibited the LPS-induced IkappaB degradation and the phosphorylation of c-jun N-terminal kinase (JNK) and c-jun. These findings suggest that the inhibition of the LPS-induced production of NO and TNF-alpha by the 2'-hydroxychalcone derivatives is due to the inhibition of NF-kappaB and AP-1 activations.

Animals↗

PubMed2004

Anti-diabetic activities of fucosterol from Pelvetia siliquosa.

Fucosterol isolated from Pelvetia siliquosa was tested for its anti-diabetic activity in vivo. Fucosterol, when administered orally at 30 mg/kg in streptozotocin-induced diabetic rats, was caused a significant decrease in serum glucose concentrations, and exhibited an inhibition of sorbitol accumulations in the lenses. Fucosterol, when administered orally at 300 mg/kg in epinephrine-induced diabetic rats, was also caused an inhibition of blood glucose level and glycogen degradation. These results demonstrated that fucosterol is a main anti-diabetic principle from the marine algae P. siliquosa.

Animals↗

PubMed2004

Constituents of the halophyte Salicornia herbacea.

Four compounds were isolated from Salicornia herbacea by repeated column chromatography. Their structures were identified as beta-sitosterol (1), stigmasterol (2), uracil (3), and isorhamnetin-3-O-beta-D-glucopyranoside (4) by spectral analysis and comparison with the published data.

Chenopodiaceae↗

PubMed2004

A benzenoid from the stem of Acanthopanax senticosus.

Seven compounds were isolated from the stem of Acanthopanax senticosus by repeated column chromatography. Their structures were elucidated as isovanillin (1), (-)-sesamin (2), isofraxidin (3), (+)-syringaresinol (4), 5-hydroxymethylfurfural (5), eleutheroside B (6), and eleutheroside E (7) by spectral analysis. Among them, isovanillin (1) was isolated for the first time from the family Araliaceae.

Benzaldehydes↗

PubMed2004

Anti-oxidant activities of Acanthopanax senticosus stems and their lignan components.

The antioxidant activities of Acanthopanax senticosus stems were evaluated in CCl4-intoxicated rats. The n-butanol fraction from the water extract of the stems, when pretreated orally at 200 mg/kg/day for 7 consecutive days in rats, was demonstrated to exhibit significant increases in antioxidant enzyme activities such as hepatic cytosolic superoxide dismutase, catalase and glutathione peroxidase by 30.31, 19.82 and 155%, respectively. The n-butanol fraction whereas showed a significant inhibition of serum GPT activity (65.79% inhibition) elevated with hepatic damage induced by CCl4-intoxication. Eleutheroside B, a lignan component, isolated from the n-butanol fraction was found to cause a moderate free radical scavenging effect on DPPH, its scavenging potency as indicated in IC50 value, being 58.5 microM. These results suggested that the stems of A. senticosus possess not only antioxidant but also hepatoprotective activities.

Administration, Oral↗

PubMed2004

Anti-platelet pentacyclic triterpenoids from leaves of Campsis grandiflora.

Five pentacyclic triterpenoids, oleanolic acid (1), hederagenin (2), ursolic acid (3), tormentic acid (4) and myrianthic acid (5), were isolated from the methanol extract of the leaves of Campsis grandiflora, and structures of the compounds were established by the spectroscopic methods. Compounds 2, 3, 4, and 5 were isolated for the first time from the genus Campsis. All of the compounds (IC50: 45.3, 32.8, 82.6, 42.9 and 46.2 microM respectively) were as equivalently inhibitive as acetylsalicylic acid (IC50: 57.0 microM) on epinephrine induced platelet aggregation.

Animals↗