Biomedical subjects

M Y Jung

Publications and source records attributed to M Y Jung.

16 recordsLinked to original sources

PubMed2006

Technical note: Improved extraction method with hexane for gas chromatographic analysis of conjugated linoleic acids.

Extraction properties of different solvents (chloroform/methanol, hexane/isopropanol, and hexane) were studied for the gas chromatographic analysis of conjugated linoleic acids (CLA) from probiotic bacteria grown in de Man, Rogosa, and Sharpe medium. As compared with chloroform/methanol and hexane/isopropanol, hexane showed comparable extraction efficiency for CLA from unspent de Man, Rogosa, and Sharpe medium, but showed minimal extraction of oleic acid originated from the emulsifier in broth. The extraction efficiency of CLA by hexane was influenced by the broth pH, showing the optimal pH of 7.0. Repeated extraction with hexane increased the yield. Extraction with hexane showed excellent recovery of spiked CLA from the spent broth with up to 97.2% (standard deviation of 1.74%). This represents the highest recovery of CLA from culture broth ever reported. The sample size was also successfully reduced to 0.5 mL to analyze CLA from the broth without impairment of analytical data. This smaller sample size in the 1.5-mL microcentrifuge tube using a small bench-top centrifuge reduced analytical time significantly.

2-Propanol↗

PubMed2004

Estimating geriatric patient's body weight using the knee height caliper and mid-arm circumference in Hong Kong Chinese.

The use of the knee height caliper is a convenient way to estimate a patient's body weight. However, the equation devised to estimate an individual's body weight was specifically designed for Caucasians and Blacks. Therefore, this study is to assess the suitability of the knee height caliper among Chinese geriatric patients residing in Hong Kong. Over a six-month period, all geriatric patients from an acute care hospital and private nursing home in the Kwun Tong were recruited into the study. Only patients/residents that were considered unstable with ascites; low blood pressure; on cardiac monitors or had respiratory difficulties were excluded. Measurements from the knee height caliper and mid-arm muscle circumference of the patients were necessary for estimating their body weights. The actual body weights measured with calibrated bed, chair or portable scales was compared with the calculated body weights from the equation. A comparison of the mean and linear regression was performed for analysis of the results. A total of 300 geriatric patients (200 females and 100 males) were recruited. The mean MAC and knee height results were as follows: 25.1 cm (SD 3.9) for females and 26.2 cm (SD 3.2) for males; and 45.75 cm (SD 2.09) for females and 48.98 cm (SD 2.09) for males respectively. The mean difference among the male group was 0.4222 (95% CI: -0.54, 1.39) with a mean estimated body weight of 58.1 kg (SD 10.1) and a mean actual body weight of 57.7 kg (SD 9.9). The mean difference among the female group was 2.9649 (95% CI: 2.30, 3.63) with a mean estimated body weight of 51.6 kg (SD 10.9) and a mean actual body weight of 48.6 kg (SD 10.1). A new equation devised from the data is as follows: Chinese males (over 60 years of age) (R-square -0.81) Weight = [knee height (cm) x 0.928 + mid-arm circumference (cm) x 2.508 - age (years) x 0.144] - 42.543 +/-9.9kg of actual weight for 95% of Chinese males; Chinese females (over 60 years of age) (R-square - 0.82) Weight (kg) = [knee height (cm) x 0.826 + mid-arm circumference (cm) x 2.116 - age (years) x 0.133] - 31.486 +/-10.1kg of actual weight for 95% of Chinese females. The results showed that the mean estimated body weight calculated from the knee height equation (for Caucasians) was significantly larger than the mean actual body weight for the Chinese subjects. This study suggests that the knee height caliper is a useful tool for estimating the body weights. However, a multi-center study is necessary to validate the new equation for the elderly Chinese population.

Aged↗

PubMed2003

The in vitro effects of dehydroepiandrosterone on human osteoarthritic chondrocytes.

OBJECTIVE: To investigate the in vitro effects of dehydroepiandrosterone (DHEA) on human osteoarthritic chondrocytes. DESIGN: Chondrocytes isolated from human osteoarthritic knee cartilage were three-dimensionally cultured in alginate beads, except for cell proliferation experiment. Cells were treated with DHEA in the presence or absence of IL-1beta. The effects on chondrocytes were analyzed using a 3-(4,5-dimethylthiazol-2yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay (for chondrocyte proliferation), a dimethylmethylene blue (DMB) assay (for glycosaminoglycan (GAG) synthesis), and an indole assay (for DNA amount). Gene expressions of type I and II collagen, metalloproteinase-1 and -3 (MMP-1 and -3), and tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as the IL-1beta-induced gene expressions of MMP-1 and -3 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein synthesis of MMP-1 and -3 and TIMP-1 was determined by Western blotting. RESULTS: The treatment of chondrocytes with DHEA did not affect chondrocyte proliferation or GAG synthesis up to 100 micro M of concentration. The gene expression of type II collagen increased in a dose-dependent manner, while that of type I decreased. DHEA suppressed the expression of MMP-1 significantly at concentrations exceeding 50 micro M. The gene expression of MMP-3 was also suppressed, but this was without statistical significance. The expression of TIMP-1 was significantly increased by DHEA at concentrations exceeding 10 micro M. The effects of DHEA on the gene expressions of MMP-1 and -3 were more prominent in the presence of IL-1beta, in which DHEA suppressed not only MMP-1, but also MMP-3 at the lower concentrations, 10 and 50 micro M, respectively. Western blotting results were in agreement with RT-PCR, which indicates that DHEA acts at the gene transcription level. CONCLUSIONS: Our study demonstrates that DHEA has no toxic effect on chondrocytes up to 100 micro M of concentration and has an ability to modulate the imbalance between MMPs and TIMP-1 during OA at the transcription level, which suggest that it has a protective role against articular cartilage loss.

Adjuvants, Immunologic↗

PubMed2001

Capsaicin-induced apoptosis in SK-Hep-1 hepatocarcinoma cells involves Bcl-2 downregulation and caspase-3 activation.

Hepatocellular carcinoma is one of the most lethal malignancies and there is no effective preventive measure in this highly malignant disease to date. In the present study, we investigated the chemopreventive potential of capsaicin (8-methyl-N- vanillyl-6-nonenamide), the principal pungent ingredient found in hot red pepper, in SK-Hep-1 hepatocellular carcinoma cells. Treatment of capsaicin inhibited growth of SK-Hep-1 cells in a concentration-dependent manner while 4-methoxy capsaicin (Met-capsaicin) was less potent. This inhibitory effect of capsaicin on SK-Hep-1 cell growth was mainly due to the induction of apoptosis as evidenced by DNA fragmentation and nuclear condensation. Furthermore, capsaicin prominently reduced the ratio of anti-apoptotic Bcl-2 to pro-apoptotic Bax and consequently increased caspase-3 activity. These results demonstrate that capsaicin efficiently induced apoptosis in SK-Hep-1 cells through a caspase-3-dependent mechanism, which may contribute to its chemopreventive function.

Anticarcinogenic Agents↗

PubMed2001

Chemopreventive allylthiopyridazine derivatives induce apoptosis in SK-Hep-1 hepatocarcinoma cells through a caspase-3-dependent mechanism.

Dietary organosulphur compounds including diallylsulphide, a component of garlic oil, were shown to inhibit the proliferation of tumour cells. Since hepatocellular carcinoma is one of the most lethal malignancies and there is no effective preventive measure to date, we wished to pursue the chemopreventive potential of the synthetic allylthiopyridazine derivatives (K compounds) on hepatocarcinoma cells. Here, we report that the K compounds efficiently inhibited SK-Hep-1 cell proliferation through induction of apoptosis. Increased chain length at the 3-position of allylthiopyridazine ring improved the potency of growth inhibition. K compounds downregulated Bcl-2, while Bax remained unchanged, reducing the ratio of Bcl-2 to Bax. We also provide evidence that the K compound-induced apoptosis involves cytochrome c release and caspase-3 activation. These results suggest that the allythiopyridazine derivatives, especially 3-propoxy-6-allylthiopyridazine, induce apoptosis in SK-Hep-1 cells through a caspase-3-dependent mechanism, which may contribute to the chemopreventive function for hepatocellular carcinoma.

Anticarcinogenic Agents↗

PubMed2001

Effects of temperature and agitation rate on the formation of conjugated linoleic acids in soybean oil during hydrogenation process.

The effects of hydrogen temperature and agitation rate on the formation of total conjugated linoleic acids (CLA) and CLA isomers were studied during hydrogenation with a selective Ni catalyst. The CLA isomers were identified by using a 100-m cyano-capillary column gas chromatograph and a silver ion-impregnated HPLC. Reaction temperature and agitation rate greatly affected the quantities of total CLA and individual CLA isomers, and the time to reach the maximum quantity of CLA in the partially hydrogenated soybean oil. As the hydrogenation temperature increased, the maximum quantity of CLA in soybean oil increased, but the time to reach the maximum CLA content decreased. By increasing the hydrogenation temperature from 170 to 210 degrees C, the quantity of CLA obtained was about 2.6 times higher. As the agitation rate decreased, the CLA formation in soybean oil increased, and the time to reach the maximum CLA content also increased. The maximum CLA contents in soybean oil obtained during hydrogenation at 210 degrees C with agitation rates of 300, 500, and 700 rpm were 162.82, 108.62, and 66.15 mg total CLA/g oil, respectively. The present data showed that it is possible to produce high-CLA-content soybean oil without major modification of fatty acid composition by short-time (10 min) selective hydrogenation under high temperature and low agitation rate conditions.

Chromatography, Gas↗

PubMed2001

Inhibitory activity of berberine on DNA strand cleavage induced by hydrogen peroxide and cytochrome c.

The inhibitory activity of berberine on the DNA single-strand cleavage induced by hydrogen peroxide and cytochrome c was measured. Berberine effectively inhibited single-strand cleavage of DNA and its effectiveness was concentration-dependent. As the berberine concentration increased, the inhibitory activity against the DNA single-strand cleavage increased. The treatments with 1, 5, 10, 50, and 100 microM berberine showed 7.7, 10.8, 32.2, 39.5, and 51.6% inhibition of DNA cleavage. This inhibitory activity of berberine against the DNA single-strand cleavage has never been reported previously. The inhibitory activity of berberine against DNA cleavage was stronger than caffeic acid and ascorbic acid. Berberine did not show strong hydroxyl radical scavenging activity, but showed strong superoxide anion radical quenching ability.

Antioxidants↗

PubMed2000

Targeted disruption of the dopamine D(2) and D(3) receptor genes leads to different alterations in the expression of striatal calbindin-D(28k).

The present study used mice deficient for dopamine D(2) and D(3) receptors to test whether the expression of these two members of the D(2) class of receptors is essential for the normal expression of three markers that characterize the neurochemical differentiation of the striatum: the calcium-binding protein calbindin, tyrosine hydroxylase and acetylcholinesterase. Results from these experiments revealed that the expression of striatal tyrosine hydroxylase (the rate-limiting enzyme of dopamine synthesis) and acetylcholinesterase is unaffected even by the combined knockout of D(2) and D(3) receptors. However, D(2) and D(3) receptor knockouts differently affect the striatal expression of calbindin-D(28k) immunoreactivity. Prominent changes in the cellular distribution of calbindin are detected in striatal neurons of D(2) mutant mice. Whereas calbindin immunolabeling of wild-type neurons is prominent in the nuclei and the cytoplasm of medium spiny neurons, in D(2) mutant mice, calbindin immunoreactivity is concentrated exclusively in the cytoplasmic rim of these neurons. Such changes in the cellular distribution of calbindin expression are not detected in mice lacking D(3) receptors. In these mutants, however, a lesser density of calbindin-immunoreactive neuropil is detected in the ventral portions of the striatum, i.e. in regions in which D(3) receptors are thought to be expressed at highest levels. Mice lacking both D(2) and D(3) receptors show both phenotypes. The altered cellular distribution of calbindin in D(2) mutants is likely to have functional consequences for some of the Ca(2+)-mediated cellular functions. The topography of the decreased density of striatal calbindin immunorectivity in D(3) mutants suggests a role for D(3) receptors in supporting the expression of striatal calbindin. The observation that mice lacking both D(2) and D(3) receptors show a combination of the D(2) and D(3) mutant phenotypes indicates that each of the different phenotypes detected in the single mutants is indeed related to the lack of the two different D(2)-like receptor subtypes.

Acetylcholinesterase↗

PubMed2000

Riboflavin-sensitized photochemical changes in beta-lactoglobulin in an aqueous buffer solution as affected by ascorbic acid.

The effects of ascorbic acid on the riboflavin-sensitized photochemical changes in beta-lactoglobulin in an aqueous buffer solution as determined by high performance gel permeation liquid chromatography (HPGPLC), insoluble protein content, and individual amino acid content during fluorescent light illumination were studied. The riboflavin-sensitized photochemical degradation of beta-lactoglobulin was effectively inhibited by ascorbic acid, and its inhibitory effectiveness was concentration dependent. The 0.1% ascorbic acid treatment showed 74.4% inhibition of beta-lactoglobulin degradation as determined by a HPGPLC during 6 h light illumination. Insolubility of beta-lactoglobulin in a buffer solution during light illumination was also effectively decreased by ascorbic acid treatment. The riboflavin-sensitized photochemical reduction of cysteine, histidine, lysine, methionine, and tryptophan in beta-lactoglobulin was high during 6 h fluorescent light illumination. The 0.1% ascorbic acid treatment exhibited 20.8% inhibition of total amino acid degradation in beta-lactoglobulin during 6 h light illumination, showing strong inhibitory activity against the degradation of arginine, aspartic acid, cystein, glycine, histidine, phenylalanine, proline, serine, and tryptophan.

Ascorbic Acid↗

PubMed2000

Antiphotooxidative activity of protoberberines derived from Coptis japonica makino in the chlorophyll-sensitized photooxidation of oil.

Antiphotooxidative components were isolated from the methanolic extract of Coptis japonica Makino by liquid-liquid partitioning fractionation, subsequent column chromatography on Sephadex LH-20 and silica gel, and preparative silica gel TLC. The isolated compounds were identified as coptisine, jatrorrizhine, berberine, and magnoflorine by a combination of spectroscopic studies using UV-visible, IR, mass-spectrometry, and NMR. Coptisine, jatrorrizhine, and berberine isolated from Coptis japonica Makino showed strong antiphotooxidative activity in the chlorophyll-sensitized photooxidation of linoleic acid. However, these compounds did not show either inhibitory activity against lipid peroxidation in rat liver microsomes nor DPPH radical scavenging activity, indicating that their antiphotooxidative activity was not due to the radical chain reaction breaking ability but due to singlet oxygen quenching activity. Commercially available authentic protoberberines (berberine chloride and palmatine chloride) also showed strong antioxidative activity in the chlorophyll-sensitized photooxidation of linoleic acid. The antiphotooxidative activities of the berberine chloride and palmatine chloride were significantly higher than that of ascorbyl palmitate in the chlorophyll-sensitized photooxidation of linoleic acid. These results clearly showed for the first time the antiphotooxidative properties of protoberberines in chlorophyll-sensitized photooxidation of oil.

Animals↗

PubMed2000

Improvement of oxidative stability of conjugated linoleic acid (CLA) by microencapsulation in cyclodextrins.

Oxidative stability of conjugated linoleic acid (CLA) encapsulated in alpha-, beta-, and gamma-cyclodextrins (designated CLA/CDs microencapsules) was studied by measuring the headspace-oxygen depletion in airtight serum bottles and by measuring the peroxide values (POV). The rate of oxygen depletion was reduced from 41.0 (control) to 21.5, 2.1, 1.2, and 1.1 micromol/L.h(-)(1) by CLA/alpha-CD microencapsules at 1:1, 1:2, 1:4, and 1:6 mole ratios, respectively, indicating that CLA oxidation was completely protected by a 1:4 mole ratio of CLA/alpha-CD. Such a protective effect by CLA/beta-CD or CLA/gamma-CD microencapsules was achieved at a 1:6 mole ratio, but the effect by CLA/beta-CD was slightly greater than that by CLA/gamma-CD. The protective effect of alpha-, beta-, and gamma-CDs for CLA oxidation was confirmed by their POV-reducing abilities in CLA/CDs. These results suggest that alpha-CD was the most effective for the protection of CLA oxidation by microencapsulation, followed by beta-CD and gamma-CD.

Cyclodextrins↗

PubMed1999

Decreased c-fos responses to dopamine D(1) receptor agonist stimulation in mice deficient for D(3) receptors.

The acute administration of dopamine D(1) receptor agonists induces the expression of the immediate early gene c-fos. In wild type mice, this induction is completely abolished by pretreatment with the D(1)-selective antagonist SCH23390, and pretreatment with the D(2)-like receptor antagonist eticlopride reduces the levels of c-fos expressed in response to D(1) receptor stimulation. Mice deficient for the dopamine D(3) receptor express levels of D(1) agonist-stimulated c-fos immunoreactivity that are lower than c-fos levels of their wild type littermates. Moreover, the acute blockade of D(2) receptors in D(3) mutant mice further reduces c-fos expression levels. These data indicate that the basal activity of both D(2) and D(3) receptors contributes to D(1) agonist-stimulated c-fos responses. The findings therefore indicate that not only D(2) but also D(3) receptors play a role in dopamine-regulated gene expression.

Animals↗

PubMed1999

Potentiation of the D2 mutant motor phenotype in mice lacking dopamine D2 and D3 receptors.

Within the D2-class of dopamine receptors, the D2 and D3 subtypes share the highest degree of similarity in their primary structure. However, the extent to which these two receptor subtypes have similar or different functional properties is unclear. The present study used gene targeting to generate mice deficient for D2, D3, and D2/D3 receptors. A comparative analysis of D2 and D3 single mutants and D2/D3 double mutants revealed that D2/D3 double mutants develop motor phenotypes that, although qualitatively similar to those seen in D2 single mutants, are significantly more severe. Furthermore, increased levels of the dopamine metabolites dihydroxyphenyl acetic acid and homovanillic acid are found in the dorsal striatum of D2 single mutants. The levels of these metabolites, however, are significantly higher in mice lacking D2 and D3 receptors. In addition, results of immunoprecipitation experiments revealed that D2 single mutants express higher levels of D3 receptor proteins during later stages of their postnatal development. These results suggest that D3 receptors compensate for some of the lacking D2 receptor functions and that these functional properties of D3 receptors, detected in mice with a D2 mutant genetic background, remain masked when the abundant D2 receptor is expressed.

Animals↗

PubMed1999

Effects of roasting on pyrazine contents and oxidative stability of red pepper seed oil prior to its extraction.

Red pepper seeds were roasted with constant stirring for 6, 9, 10, and 12 min at 210 degrees C, and oils were extracted from the roasted red pepper seeds using an expeller. The iodine values and fatty acid compositions of red pepper seed oils did not change with roasting time. The fatty acid composition of the oil obtained from the red pepper seeds roasted for 6 min was 0.24% myristic acid, 13. 42% palmitic acid, 0.33% palmitoleic acid, 2.07% stearic acid, 10. 18% oleic acid, 73.89% linoleic acid, and 0.37% linolenic acid, showing a fatty acid composition similar to that of high-linoleate safflower oil. Thirteen alkylpyrazines were identified in the roasted red pepper seed oils: 2-methylpyrazine, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, 2-ethylpyrazine, 2-ethyl-6-methylpyrazine, 2-ethyl-5-methylpyrazine, trimethylpyrazine, 2,6-diethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, tetramethylpyrazine, 2, 3-diethyl-5-methylpyrazine, 2-isobutyl-3-methylpyrazine, and 3, 5-diethyl 2-methylpyrazine. The pyrazine content increased markedly as the roasting time increased, showing 2.63, 5.01, 8.48, and 13.10 mg of total pyrazine/100 g of oils from the red pepper seeds roasted for 6, 8, 10, and 12 min, respectively, at 210 degrees C. 2, 5-Dimethylpyrazine in the roasted red pepper seed oil seemed to be the component most responsible for the pleasant nutty aroma of the oils. The oxidative stabilities of oils increased greatly as the roasting time increased.

Capsicum↗

PubMed1999

Conjugated linoleic acid isomers in partially hydrogenated soybean oil obtained during nonselective and selective hydrogenation processes.

Partially hydrogenated soybean oil samples were collected during selective and nonselective hydrogenation processes. The formation of conjugated linoleic acids (CLAs) during hydrogenation was greatly dependent on the types and duration of hydrogenation processes. During hydrogenation processes, CLA contents increased initially. After reaching maximum CLA content, the content decreased during hydrogenation. Selective hydrogenation was much more favorable for the formation of conjugated linoleic acids. With nonselective hydrogenation process, the total CLA content was a maximum (9.06 mg total CLA/g oil) at 35 min. However, with the selective hydrogenation process, the total CLA content was a maximum (98.27 mg total CLA/g oil) at 210 min. The CLA contents in some of the tested selectively hydrogenated soybean oils were among the highest ever reported in foods.

Esters↗

PubMed1995

Proteolytic processing is required for viral superantigen activity.

The mouse mammary tumor virus-7 superantigen (vSAG7) is proteolytically processed in B cells at as many as three positions. Proteolytic processing appears to be important for superantigen activity because a processed form of vSAG7 was predominant among those forms that were found to bind to major histocompatibility complex class II molecules. To determine the functional significance of proteolytic processing, a mutation was introduced in vSAG7 at one of the sites where proteolytic cleavage is thought to take place in B cells. Elimination of the putative processing site at position 171 abrogated detectable vSAG7 surface expression in B cells, indicating that proteolytic processing is required for vSAG7 function. Coexpression in insect cells of vSAG7 and furin, a proprotein-processing enzyme, also demonstrated that furin could process vSAG7 at position 171.

Amino Acid Sequence↗