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Biomedical subjects

Y Yoon

Publications and source records attributed to Y Yoon.

At least 19 recordsLinked to original sources
PubMed2005

Reduction of Listeria monocytogenes populations during exposure to a simulated gastric fluid following storage of inoculated frankfurters formulated and treated with preservatives.

The effect of a simulated gastric fluid (adjusted to pH 1.0 with HCl) on Listeria monocytogenes, inoculated postprocessing on pork frankfurters formulated with sodium lactate (SL) and sodium diacetate (SD) and not dipped or dipped in solutions of lactic acid or acetic acid, was evaluated during storage of the frankfurters at 10 degrees C for 40 days. Pork frankfurters containing 1.8% SL, 0.25% SD, 1.8% SL+0.125% SD, or 1.8% SL+0.25% SD were inoculated with 10(2)-10(3) CFU/cm2 of a 10-strain preparation of L. monocytogenes and were not dipped or dipped for 2 min in solutions of 2.5% lactic or acetic acid before they were vacuum-packaged and stored. Survival of L. monocytogenes was determined after exposure of frankfurters for 0, 20, 40, and 60 min to the simulated gastric fluid after storage for 0, 10, 20, 30, or 40 days. Growth of L. monocytogenes on frankfurters formulated with antimicrobials was inhibited in the order control <SL<0.25% SD<SL+0.125% SD<SL+0.25% SD. Survival of L. monocytogenes during exposure to simulated gastric fluid was higher on those frankfurters on which there had been extensive growth of the pathogen than on frankfurters on which growth had been inhibited. Inclusion of single antimicrobials in the formulation of not dipped frankfurters appeared to increase resistance of L. monocytogenes to simulated gastric fluid provided the initial level of the pathogen exposed to the simulated gastric fluid was higher than 5 log CFU/cm2. Although the combinations of SL and SD used in the formulation of not dipped frankfurters inhibited growth of L. monocytogenes, prolonged (40 days) storage of such frankfurters induced slight resistance to simulated gastric fluid. The frankfurter formulation of 0.25% SD and dipping in 2.5% lactic acid appeared to increase resistance of L. monocytogenes to simulated gastric fluid following growth during prolonged (days 20 to 40) storage. Use of 2.5% acetic acid dipping combined with antimicrobials in the formulation inhibited growth of L. monocytogenes on frankfurters and subsequent detectable survival after exposure to simulated gastric fluid.

Animals↗
PubMed2005

Transport of target anions, chromate (Cr (VI)), arsenate (As (V)), and perchlorate (ClO4-), through RO, NF, and UF membranes.

Rejection and transport of chromate (Cr (VI)), arsenate (As (V)), and perchlorate (ClO4-) by and through reverse osmosis, nanofiltration, and ultrafiltration were found to be affected by solution pH and ionic strength. In this study, the rejection of these target ionic contaminants increased with increasing pH at the same conductivity (ionic strength) for the tested membranes, regardless of salt type. General trends showed that the rejection followed the order: CaCl2 < KCl < or = K2SO4, at the same pH and conductivity condition. The rejection also significantly decreased as conductivity was increased regardless of the salt type. These results support the notion that a more negative surface charge due to increasing pH and/or decreasing ionic strength (conductivity) enhances rejection; lower molecular weight cut-off also enhances rejection. Measured values of hindered diffusion coefficient through the membrane pores (Dp) for the target contaminants significantly decreased as pH was increased, regardless of salt type at the same conductivity. At the same pH and conductivity, the Dp of the target contaminants follows the order: CaCl2 > KCl > K2SO4, in the presence of different types of salts. The Dp of the target contaminants significantly increased as conductivity was increased regardless of the salt type. The rejection data were modeled by application of a non-equilibrium thermodynamic model. The rejection model has five transport parameters: the molecular transport coefficient (omega), osmotic pressure gradient (deltaII), molecular reflection coefficient (sigma), the average bulk fluid interfacial concentration between the feed and permeate side (C(avg)), and the solvent flux (Jv). The transport parameters were determined by independent measurements (and calculation with minimum assumptions.) Measurements and predictions of the target contaminant transport were in good agreement.

Arsenates↗
PubMed2004

Characterization of nutty flavor in cheddar cheese.

The objectives of this study were to determine the volatile components responsible for the sensory perception of nutty flavor in Cheddar cheese. Cheddar cheeses with and without nutty flavors were selected by descriptive sensory analysis. Volatile aroma components from Cheddar cheeses with and without nutty flavors were isolated and characterized using solvent extraction with high vacuum distillation, dynamic headspace analysis, gas chromatography-olfactometry, and gas chromatography-mass spectrometry. More than 50 aroma-active compounds were detected in Cheddar cheeses. Consistent differences were observed between nutty and not nutty Cheddar cheeses. Strecker aldehydes were detected in higher amounts in Cheddar cheeses with nutty flavors compared with Cheddar cheeses without nutty flavors. Strecker aldehydes, dimethyl sulfide, and propionic acid were evaluated in young and aged Cheddar cheese models for nutty flavor by descriptive sensory analysis. Dimethyl sulfide and propionic acid did not contribute to nutty flavor in Cheddar cheese. The addition of Strecker aldehydes to young (<4 mo old) Cheddar cheese models resulted in nutty/malty flavor perceived by sensory analysis. When Strecker aldehydes were incorporated into aged (>9 mo old) Cheddar cheese models, nutty flavor perception increased. Strecker aldehydes contribute to nutty flavor in aged Cheddar cheese.

Aldehydes↗
PubMed2004

Effect of simulated spray chilling with chemical solutions on acid-habituated and non-acid-habituated Escherichia coli O157:H7 cells attached to beef carcass tissue.

Samples (10 by 20 by 2.5 cm) of beef carcass tissue were inoculated (10(4) to 10(5) CFU/cm2) with Escherichia coli O157: H7 that was either non-acid habituated (prepared by incubating at 15 degrees C for 48 h in inoculated filter-sterilized composite [1:1] of hot and cold water meat decontamination runoff fluids, pH 6.05) or acid habituated (prepared in inoculated water fluids mixed with filter-sterilized 2% lactic acid [LA] runoff fluids in a proportion of 1/99 [vol/vol], pH 4.12). The inoculated surfaces were exposed to conditions simulating carcass chilling (- 3 degrees C for 10 h followed by 38 h at 1 degree C). Treatments applied to samples (between 0 and 10 h) during chilling included the following: (i) no spraying (NT) or spraying (for 30 s every 30 min) with (ii) water, (iii) cetylpyridinium chloride (CPC; 0.1 or 0.5%), (iv) ammonium hydroxide (AH; 0.05%), (v) lactic acid (LA; 2%), (vi) acidified sodium chlorite (ASC; 0.12%), (vii) peroxyacetic acid (PAA; 0.02%), (viii) sodium hydroxide (SH; 0.01%), or (ix) sodium hypochlorite (SC; 0.005%) solutions of 4 degrees C. Samples were taken at 0, 10, 24, 36, and 48 h of the chilling process to determine changes in E. coli O157:H7 populations. Phase 1 tested water, SH, PAA, LA, and 0.5% CPC on meat inoculated with non-acid-habituated pathogen populations, whereas phase 2 tested water, SC, AH, ASC, LA, and 0.1% CPC on meat inoculated with acid- and non-acid-habituated populations. Reductions in non-acid-habituated E. coli O157:H7 populations from phase 1 increased in the order NT = water = SH < PAA < LA < CPC. Reductions from phase 2 for acid-habituated cells increased in the order NT = water = SC < ASC = LA = AH < CPC, whereas on non-acid-habituated cells the order observed was NT = water = SC < AH = ASC < LA < CPC. Previous acid habituation of E. coli O157:H7 inocula rendered the cells more resistant to the effects of spray chilling, especially with acid; however, the trend of reduction remained spray chilling with water = non-spray chilling < spray chilling with chemical solutions.

Animals↗
PubMed2004

Agricultural recycling of the by-product concentrate of livestock wastewater treatment plant processed with VSEP RO and bio-ceramic SBR.

One of the problems in a reverse osmosis process for livestock wastewater treatment is disposal of the by-product concentrate. The agricultural recycling of the concentrate is more cost saving than a further treatment. Application of the concentrate reduces the chemical fertilizer amendment. The agricultural recycling of the concentrate from the Kimhae livestock wastewater treatment plant, processed with the VSEP RO and bio-ceramic SBR, was studied. The concentrate includes non-biodegradable humic ubstance and residual inorganic ions (NH4+, NO3-, PO4(3-), K+, etc.). The contents of N, P and K were 1,650, 382 and 2,059 mg L(-1), respectively. The total acidity of humic acids extracted from the concentrate was 5.17 cmol(+) g(-1), composed of 2.38 cmol(+) g(-1) of carboxylic group and 2.79 cmol(+) g(-1) of phenolic hydroxyl group. Coliforms and E. coli were not detected in the concentrate. The yield of rice plant with the concentrate applied to it resulted in similar production to that with chemical fertilizer applied. The water extractable nitrate content of the concentrate-applied land did not exceed that of chemical fertilizer applied, at soil depths of 30 and 60 cm. The percolated amount of nitrate into the water table in arable land with the concentrate applied showed a similar level to that treated with the chemical fertilizer.

Agriculture↗
PubMed2002

Genetic contribution to factor VII levels in families of patients undergoing coronary arteriography.

An elevated plasma level of factor VII is a risk factor for coronary artery disease. We investigated environmental, familial, and genetic influences on factor VII activity in 508 family members of 87 probands who underwent elective coronary arteriography. Maximum likelihood methods were used to fit several genetic and non-genetic models of inheritance to these data to determine whether an unobserved Mendelian major gene could explain the familial distribution of factor VII. Factor VII activities were adjusted for age, gender, body mass index, smoking, alcohol consumption, menopause status, and triglycerides prior to this segregation analysis (this model accounted for 33.5% of the total variation). Adjusted factor VII activities showed strong familial aggregation with an estimated parent-offspring correlation of 0.34, sibling correlation of 0.36 and a smaller spouse correlation of 0.16. Regressive models were used to test genetic and non-genetic models in these 87 families. Mendelian single-locus models with either two or three underlying genotypic distributions of factor VII activities were best supported by these data. Essentially, these Mendelian models suggest most individuals come from a low distribution (mean, 116%), with a few individuals homozygous for a high allele drawn from a distribution with a mean of 166%. Future linkage studies may be worthwhile to further clarify the mechanisms controlling factor VII activity.

Adolescent↗
PubMed2001

Mitochondrial division: New partners in membrane pinching.

Mitochondrial division is a complex process requiring the synergistic actions of multiple factors, including mechanical enzymes and accessory proteins. Recent studies have identified a number of these factors and started to elucidate how they act together to bring about mitochondrial fission.

Animals↗
PubMed2001

Characterization of publicly available SNPs in the Korean population.

Single-nucleotide polymorphisms (SNPs) are the most abundant form of genetic variations and have a great potential for mapping studies of complex genetic traits. Currently a great deal of effort is invested in the identification of SNPs, and a large volume of data is already available through public databases (NCBI, NCI, WICGR, HGBASE). For an association mapping study, SNP allele frequencies in the population are critical. As an initial step toward construction of an SNP database of the Korean population, we have determined the allele frequencies of 300 cSNPs selected from the public database in 24 individuals. Among the tested markers, approximately 23% did not show polymorphism in the population. The results suggest that the ethnic and population based differences should be considered in the selection of SNPs for the study of complex diseases with association mapping methods.

Alleles↗
PubMed2001

Cleaning strategies for flux recovery of an ultrafiltration membrane fouled by natural organic matter.

One of the most common problems encountered in water treatment applications of membranes is fouling. Natural organic matter (NOM) represents a particularly problematic foulant. Membranes may be fouled by relatively hydrophilic and/or hydrophobic NOM components, depending on NOM characteristics, membrane properties, and operating conditions. To maximize flux recovery for an NOM-fouled ultrafiltration membrane (NTR 7410), chemical cleaning and hydraulic rinsing with a relatively high cross-flow velocity were investigated as cleaning strategies. The modification of the membrane surface with either an anionic or a cationic surfactant was also evaluated to minimize membrane fouling and to enhance NOM rejection. Foulants from a hydrophobic NOM source (Orange County ground water (OC-GW)) were cleaned more effectively in terms of permeate flux by acid and caustic cleanings than foulants from a relatively hydrophilic NOM source (Horsetooth surface water (HT-SW)). An anionic surfactant (sodium dodecyl sulfate (SDS)) was not effective as a cleaning agent for foulants from either hydrophobic or hydrophilic NOM sources. High ionic strength cleaning with 0.1 M NaCl was comparatively effective in providing flux recovery for NOM-fouled membranes compared to other chemical cleaning agents. Increased cross-flow velocity and longer cleaning time influenced the efficiency of caustic cleaning, but not high ionic strength cleaning. The membrane was successfully modified only with the cationic surfactant; however, enhanced NOM rejection was accompanied by a significant flux reduction.

Acids↗
PubMed2001

Mammalian dynamin-like protein DLP1 tubulates membranes.

Dynamins are large GTPases with mechanochemical properties that are known to constrict and tubulate membranes. A recently identified mammalian dynamin-like protein (DLP1) is essential for the proper cellular distribution of mitochondria and the endoplasmic reticulum in cultured cells. In this study, we investigated the ability of DLP1 to remodel membranes similar to conventional dynamin. We found that the expression of a GTPase-defective mutant, DLP1-K38A, in cultured cells led to the formation of large cytoplasmic aggregates. Electron microscopy (EM) of cells expressing DLP1-K38A revealed that these aggregates were comprised of membrane tubules of a consistent diameter. High-magnification EM revealed the presence of many regular striations along individual membrane tubules, and immunogold labeling confirmed the association of DLP1 with these structures. Biochemical experiments with the use of recombinant DLP1 and labeled GTP demonstrated that DLP1-K38A binds but does not hydrolyze or release GTP. Furthermore, the affinity of DLP1-K38A for membrane is increased compared with wild-type DLP1. To test whether DLP1 could tubulate membrane in vitro, recombinant DLP1 was combined with synthetic liposomes and nucleotides. We found that DLP1 protein alone assembled into sedimentable macromolecular structures in the presence of guanosine-5'-O-(3-thio)triphosphate (GTPgammaS) but not GTP. EM of the GTPgammaS-treated DLP1 revealed clusters of stacked helical ring structures. When liposomes were included with DLP1, formation of long membrane tubules similar in size to those formed in vivo was observed. Addition of GTPgammaS greatly enhanced membrane tubule formation, suggesting the GTP-bound form of DLP1 deforms liposomes into tubules as the DLP1-K38A does in vivo. These results provide the first evidence that the dynamin family member, DLP1, is able to tubulate membranes both in living cells and in vitro. Furthermore, these findings also indicate that despite the limited homology to conventional dynamins (35%) these proteins remodel membranes in a similar manner.

Amino Acid Substitution↗
PubMed2001

Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography.

UNLABELLED: Seo TS, Oh JH, Lee DH, et al. Radiologic anatomy of the rabbit liver on hepatic venography, arteriography, portography, and cholangiography. Invest Radiol 2001;36:186-192. RATIONALE AND OBJECTIVES: The radiologic anatomy of rabbit liver has received little study but is important in many experimental investigations. METHODS: Twenty-four rabbits were studied by using hepatic venograms, aortograms, hepatic arteriograms, cholangiograms, and portograms. RESULTS: In all cases, the right, middle, and left hepatic veins drained into the inferior vena cava just below the diaphragm, and the caudate lobe hepatic vein drained more inferiorly. The proper hepatic artery was a branch of the common hepatic artery in 96%. The first branch of the proper hepatic artery was the caudate lobe artery. The remaining main hepatic artery was divided into the right and left hepatic arteries. The left hepatic artery was further divided into the medial and lateral segmental branches in 95%. The anatomy of the portal vein or bile duct was the same as the hepatic artery in 100% of cases. CONCLUSIONS: Knowledge of the normal patterns and variations of the vessels and bile duct will be helpful for experiments of the rabbit liver in future studies.

Animals↗
PubMed2001

Prevalence of hepatitis E virus antibodies in Canadian swine herds and identification of a novel variant of swine hepatitis E virus.

Swine hepatitis E virus is a newly identified potentially zoonotic virus from pigs of particular concern for possible direct transmission to a human xenotransplant recipient by organ transplantation. In the present study, prevalence of serum antibodies to hepatitis E virus was examined in Canadian swine herds. A total of 998 serum samples collected from 6-month-old healthy slaughter hogs were examined by enzyme immunoassay and Western blot analysis for antibodies to the recombinant open reading frame 3 (ORF3) protein of hepatitis E virus expressed in Escherichia coli. These samples represented more than 80 different swine production units from five major swine-producing provinces across Canada. From this study, 594 samples (59.4%) were found to be positive for hepatitis E virus antibody. The seroprevalence was higher in Quebec (88.8%) and Ontario (80.1%) than in Alberta and Saskatchewan (38.3%). By PCR using a pair of oligonucleotide primers deduced from the ORF2 sequence of human hepatitis E virus, a specific hepatitis E virus sequence was recovered from feces of pigs. The nucleotide sequence identity between the U.S. swine hepatitis E virus and the Canadian isolate (SK3) was only 85.8%, suggesting that genotypic variations may exist in swine hepatitis E virus in North America. Among 165 serum samples collected from humans in Saskatchewan, 2.4% were found to be positive for antibodies to the hepatitis E virus ORF3 protein. Our data indicate that hepatitis E virus is highly prevalent in commercial swine populations in Canada and support the suggestion that the swine hepatitis E virus may be an important zoonotic agent for humans.

Animals↗
PubMed2001

A Web-based interactive education programme on vaccination for public health officials.

Health and Welfare Training Center of Korean National Institute of Health (KNIH) has developed various education curricula for officials who are involved in the public health or welfare sectors. Still almost all education programmes are off-line based. In off-line settings, both the lecturers and the students should come to NIH from their counties to join the education programmes, and it is impossible for the students to review or to re-practice the education contents. We developed a prototype on-line setting education programmes to provide a more convenient and more effective service to the officials. This web-based interactive education programme consisted of the specific objectives on vaccination for the public health officials who were working for the national immunization programmes. It became a prototype of web-based education and was evaluated by the participants in April, 2001. From the evaluation, we improved the contents and tried to develop more subjects for the officials' training.

Adult↗
PubMed2001

Ultrasonographic observation of intestinal mobility of dogs after acupunctural stimulation on acupoints ST-36 and BL-27.

objectives of this study were to observe normal peristalsis and mixing (or segmental movements) and to evaluate an acupuncture stimulation (ST-36 and BL-27) on the intestinal (duodenum) motility in normal dogs using duplex Doppler sonography. Fifteen healthy Beagle dogs were used for this experiment after the administration of warm saline and pellet feeding. The duodenal motility was examined using duplex Doppler sonography. Six hours after the pellet feeding, an electroacupuncture stimulation at ST-36 and BL-27 was applied and the duodenal motility was examined using duplex Doppler sonography pre-stimulation, during the stimulation and post-stimulation. After saline and pellet administration, the duplex Doppler sonograms showed 3 types of peristalsis and a mixing type (or segmental movement) of duodenum motility. In the peristalsis types, most yielded high-amplitude signals which had one high peak (type-1), two high peaks (type-2), and three high peaks (type-3) and lasted more than 1.3 seconds. Mixing type of duodenum motility had weak signals and were lasted more than 1.5 seconds. Among the peristalsis types, the type 1 and type 2 were predominant and the type 3 was rarely observed. The frequency of intestinal motility stimulated by ST-36 acupoint was increased during the acupuncture stimulation (20% increase compared to the basal value) and decreased (7% decrease compared to the basal value) after stimulation. The frequency of intestinal motility stimulated by BL-27 acupoint was decreased during the acupuncture stimulation (31% decrease compared to the basal value) and increased (18% increase compared to the basal value) after stimulation. There was a significant increase between the value found in during and the post-stimulation tests. We conclude that duplex Doppler studies permit a graphic visualization of intestinal movements which can be qualitatively and quantitatively analyzed using this technique, it is possible to evaluate the gastrointestinal motility after an acupuncture

Acupuncture Points↗
PubMed2000

Natural and radiation-induced degeneration of primordial and primary follicles in mouse ovary.

The present study deals with the morphological changes of the degenerating primordial and primary follicles induced by gamma-radiation. Prepubertal female mice of 3 weeks old ICR strain were gamma-irradiated with the dose of LD(80(30)) (8.3 Gy). The ovaries were collected at 3, 6 and 12 h after irradiation. The largest cross-sections were prepared by histological semithin sections for microscopical observations. The ratio (%) of normal to atretic follicles decreased with time after the irradiation in primordial follicles and in primary follicles as well. At 6 h after irradiation, the number of degenerated primordial follicles increased. Germinal vesicles disappeared and lipid droplets increased in number. Granulosa cells became round in shape and apoptotic cells started to appear. The ooplasmic membrane was not recognizable. The ratio of normal to atretic primordial follicles in the control group was 62.5. Then it became lower with time after the irradiation. It went down to 51.6, 49.0, 11.1 and 7.1 at 0, 3, 6 and 12 h, respectively. The ratio of normal to atretic primary follicles in the control mouse ovary was 81.3. It was 80.0, 75.0, 45.5 and 33. 3 at 0, 3, 6 and 12 h after irradiation, respectively. It is concluded that the ionizing radiation acutely induces the degeneration of primordial and primary follicles. The pattern of degeneration is one of the following: (1) apoptosis of one or more granulosa cells with a relatively intact oocyte, (2) apoptosis of an oocyte with intact follicle cells, or (3) apoptotic degenerations of both kinds of cells. These results can provide morphological clues for the identification of the degenerating primordial and primary follicles in normal and irradiated mouse ovaries.

Animals↗
PubMed2000

The methylenetetrahydrofolate reductase gene is associated with increased cardiovascular risk in Japan, but not in other populations.

The methylenetetrahydrofolate reductase (MTHFR) gene has been associated with increased risk for cardiovascular disease in some, but not all studies. Our data sources included a MEDLINE search of the literature published before December 1998, a bibliography review, and expert consultation. Of 23 studies initially identified, 18 (9855 persons) met the inclusion criteria. Information on sample size, study design, Hardy-Weinberg equilibrium, method of genotype determination, plasma folate and homocysteine were abstracted by two reviewers using a standardized protocol. The overall odds ratio of the MTHFR gene on cardiovascular disease was estimated using the Mantel-Haenzel method. From 12 studies with angiographically-confirmed coronary artery disease (CAD), the overall odds ratio (OR) for CAD among those with heterozygous (V/A) was 1.3 (95% CI, 1.1-1.5), while it was 1.4 (1.2-1.6) for the homozygous mutant (V/V) compared to those with homozygous normal (A/A). However, the overall odds ratio for CAD among those with the V/V genotype versus A/A genotype was not statistically significant (OR: 1.1; 95% CI: 0.9-1.3) after excluding three Japanese studies. The corresponding OR for the three Japanese studies was 2.0 (1.6-2.7). For six studies with myocardial infarction (MI), the overall OR of MI was 1.0 (0.8-1.1) for those with the V/A genotype and 0.9 (0.7-1.1) for those with the V/V genotype, respectively; none of these ORs for MI was statistically significant. The MTHFR gene is associated with increased risk for CAD in Japan, but not in other populations.

Asian People↗
PubMed2000

Protective effects of Orostachys japonicus A. Berger (Crassulaceae) on H2O2-induced apoptosis in GT1-1 mouse hypothalamic neuronal cell line.

Oxidative stress is a major cause of neurodegenerative diseases, so the protection of neuronal cells from reactive oxygen species can be beneficial for the prevention and treatment of these diseases. Methanol extract of Orostachys japonicus A. Berger (Crassulaceae), a traditional oriental medical herb, was shown to have a protective effect on H2O2-induced apoptosis in GT1-1 mouse hypothalamic neuronal cell line which was detected by flow cytometry after propidium iodide staining. Among fractions of O. japonicus, chloroform fraction had the highest protective effect, and water fraction had no protective effect suggesting that the active ingredients might be hydrophobic compounds.

Animals↗