Showing papers by "Yonsei University published in 1999"

Cross-Cultural Variations in Predictors of Life Satisfaction: Perspectives from Needs and Values

Abstract: The authors tested for cross-cultural difference in predictors of life satisfaction. In Study 1 (39 nations, N = 54, 446), they found that financial satisfaction was more strongly associated with life satisfaction in poorer nations, whereas home life satisfaction was more strongly related to life satisfaction in wealthy nations. In Study 2 (39 nations, N = 6,782), the authors found that satisfaction with esteem needs (e.g., the self and freedom) predicted global life satisfaction more strongly among people in individualist nations than people in collectivist nations. The present investigation provides support for the needs and values-as-moderators model of subjective well-being at the cultural level. The need for theories that account for culture-specific as well as universal predictors of life satisfaction will be discussed.

Dynamic Association of Proteasomal Machinery with the Centrosome

Abstract: Although the number of pathologies known to arise from the inappropriate folding of proteins continues to grow, mechanisms underlying the recognition and ultimate disposition of misfolded polypeptides remain obscure. For example, how and where such substrates are identified and processed is unknown. We report here the identification of a specific subcellular structure in which, under basal conditions, the 20S proteasome, the PA700 and PA28 (700- and 180-kD proteasome activator complexes, respectively), ubiquitin, Hsp70 and Hsp90 (70- and 90-kD heat shock protein, respectively) concentrate in HEK 293 and HeLa cells. The structure is perinuclear, surrounded by endoplasmic reticulum, adjacent to the Golgi, and colocalizes with gamma-tubulin, an established centrosomal marker. Density gradient fractions containing purified centrosomes are enriched in proteasomal components and cell stress chaperones. The centrosome-associated structure enlarges in response to inhibition of proteasome activity and the level of misfolded proteins. For example, folding mutants of CFTR form large inclusions which arise from the centrosome upon inhibition of proteasome activity. At high levels of misfolded protein, the structure not only expands but also extensively recruits the cytosolic pools of ubiquitin, Hsp70, PA700, PA28, and the 20S proteasome. Thus, the centrosome may act as a scaffold, which concentrates and recruits the systems which act as censors and modulators of the balance between folding, aggregation, and degradation.

Monsoon changes for 6000 years ago: Results of 18 simulations from the Paleoclimate Modeling Intercomparison Project (PMIP)

Abstract: Amplification of the northern hemisphere seasonal cycle of insolation during the mid-Holocene causes a northward shift of the main regions of monsoon precipitation over Africa and India in all 18 simulations conducted for the Paleoclimate Modeling Intercomparison Project (PMIP). Differences among simulations are related to differences in model formulation. Despite qualitative agreement with paleoecological estimates of biome shifts, the magnitude of the monsoon increases over northern Africa are underestimated by all the models.

Multiple Stellar Populations in the Globular Cluster omega Centauri as Tracers of a Merger Event

Abstract: The discovery of the Sagittarius dwarf galaxy, which is being tidally disrupted by and merging with the Milky Way, supports the view that the halo of the Galaxy has been built up at least partially by the accretion of similar dwarf systems. The Sagittarius dwarf contains several distinct populations of stars, and includes M54 as its nucleus, which is the second most massive globular cluster associated with the Milky Way. The most massive globular cluster is omega Centauri, and here we report that omega Centauri also has several distinct stellar populations, as traced by red-giant-branch stars. The most metal-rich red-giant-branch stars are about 2 Gyr younger than the dominant metal-poor component, indicating that omega Centauri was enriched over this timescale. The presence of more than one epoch of star formation in a globular cluster is quite surprising, and suggests that omega Centauri was once part of a more massive system that merged with the Milky Way, as the Sagittarius dwarf galaxy is in the process of doing now. Mergers probably were much more frequent in the early history of the Galaxy and omega Centauri appears to be a relict of this era.

Multiple stellar populations in the globular cluster ω Centauri as tracers of a merger event

Abstract: The discovery of the Sagittarius dwarf galaxy1, which is being tidally disrupted by and merging with the Milky Way, supports the view that the halo of the Galaxy has been built up at least partially by the accretion of similar dwarf systems. The Sagittarius dwarf contains several distinct populations of stars2,3, and includes M54 as its nucleus, which is the second most massive globular cluster associated with the Milky Way. The most massive globular cluster is ω Centauri, and here we report that ω Centauri also has several distinct stellar populations, as traced by red-giant-branch stars. The most metal-rich red-giant-branch stars are about 2 Gyr younger than the dominant metal-poor component, indicating that ω Centauri was enriched over this timescale. The presence of more than one epoch of star formation in a globular cluster is quite surprising, and suggests that ω Centauri was once part of a more massive system that merged with the Milky Way, as the Sagittarius dwarf galaxy is in the process of doing now. Mergers probably were much more frequent in the early history of the Galaxy and ω Centauri appears to be a relict of this era.

Copper(II)-induced self-oligomerization of alpha-synuclein.

Abstract: alpha-Synuclein is a component of the abnormal protein depositions in senile plaques and Lewy bodies of Alzheimer's disease (AD) and Parkinson's disease respectively. The protein was suggested to provide a possible nucleation centre for plaque formation in AD via selective interaction with amyloid beta/A4 protein (Abeta). We have shown previously that alpha-synuclein has experienced self-oligomerization when Abeta25-35 was present in an orientation-specific manner in the sequence. Here we examine this biochemically specific self-oligomerization with the use of various metals. Strikingly, copper(II) was the most effective metal ion affecting alpha-synuclein to form self-oligomers in the presence of coupling reagents such as dicyclohexylcarbodi-imide or N-(ethoxycarbonyl)-2-ethoxy-1,2-dihydroquinoline. The size distribution of the oligomers indicated that monomeric alpha-synuclein was oligomerized sequentially. The copper-induced oligomerization was shown to be suppressed as the acidic C-terminus of alpha-synuclein was truncated by treatment with endoproteinase Asp-N. In contrast, the Abeta25-35-induced oligomerizations of the intact and truncated forms of alpha-synuclein were not affected. This clearly indicated that the copper-induced oligomerization was dependent on the acidic C-terminal region and that its underlying biochemical mechanism was distinct from that of the Abeta25-35-induced oligomerization. Although the physiological or pathological relevance of the oligomerization remains currently elusive, the common outcome of alpha-synuclein on treatment with copper or Abeta25-35 might be useful in understanding neurodegenerative disorders in molecular terms. In addition, abnormal copper homoeostasis could be considered as one of the risk factors for the development of disorders such as AD or Parkinson's disease.

Isolation and characterization of a thermophilic lipase from Bacillus thermoleovorans ID‐1

Abstract: A thermophilic microorganism, Bacillus thermoleovorans ID-1, isolated from hot springs in Indonesia, showed extracellular lipase activity and high growth rates on lipid substrates at elevated temperatures. On olive oil (1.5%, w/v) as the sole carbon source, the isolate ID-1 grew very rapidly at 65°C with its specific growth rate (2.50 h−1) and its lipase activity reached the maximum value of 520 U l−1 during the late exponential phase and then decreased. In addition to this, isolate ID-1 could grow on a variety of lipid substrates such as oils (olive oil, soybean oil and mineral oil), triglycerides (triolein, tributyrin) and emulsifiers (Tween 20, 40). The excreted lipase of ID-1 was purified 223-fold to homogeneity by ammonium sulfate precipitation, DEAE-Sephacel ion-exchange chromatography and Sephacryl S-200 gel filtration chromatography. As a result, the relative molecular mass of the lipase was determined to be 34 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed optimal activity at 70–75°C and pH 7.5 and exhibited 50% of its original activity after 1 h incubation at 60°C and 30 min at 70°C and its catalytic function was activated in the presence of Ca2+ or Zn2+.

Simulations of temperature and turbulence structure of the oceanic boundary layer with the improved near-surface process

Abstract: An improved model for the oceanic boundary layer is presented in view of the recent observation of the microstructure of the upper ocean including the high dissipation rate near the sea surface. In the new model the surface boundary conditions for both the turbulent kinetic energy flux and the roughness length scale are modified. The parameterization of stratification effects on turbulence is improved, and the convective process is reformulated on the basis of the observation of uniform temperature and velocity profiles within the convective mixed layer. Evolutions of the profiles of both the dissipation rate and temperature of the observation data Patches Experiment as well as the time series of the sea surface temperature over the observation days, are successfully simulated during a diurnal cycle for the first time. It is also shown that the model reproduces various important features of the oceanic boundary layer, for example, the formation of a diurnal thermocline, the profiles of buoyancy flux, and the magnitudes of the buoyancy gradients both within the mixed layer and at the diurnal thermocline. Performance of the model is compared with that of the widely used Mellor-Yamada model.

Two distinct mechanisms are involved in 6-hydroxydopamine- and MPP+- induced dopaminergic neuronal cell death: Role of caspases, ROS, and JNK

Abstract: In this study, we examined the possibility that MPTP and 6-hydroxydopamine (6-OHDA) act on distinct cell death pathways in a murine dopaminergic neuronal cell line, MN9D. First, we found that cells treated with 6-OHDA accompanied ultrastructural changes typical of apoptosis, whereas MPP+ treatment induced necrotic manifestations. Proteolytic cleavage of poly(ADP-ribose)polymerase by caspase was induced by 6-OHDA, whereas it remained uncleaved up to 32 h after MPP+ treatment and subsequently disappeared. Accordingly, 6-OHDA- but not MPP+-induced cell death was significantly attenuated in the presence of a broad-spectrum caspase inhibitor, N-benzyloxy-carbonyl-Val-Ala-Asp-fluomethylketone (Z-VAD-fmk). As measured by fluorometric probes, the level of reactive oxygen species (ROS) significantly increased after 6-OHDA treatment. In contrast, the level of dihydroethidium-sensitive ROS following MPP+ treatment remained unchanged while a slight increase in dichlorofluorescin-sentive ROS was temporarily observed. As demonstrated by immunoblot analysis, the level of superoxide dismutase was down-regulated following 6-OHDA treatment, whereas it remained unchanged after MPP+ treatment. Cotreatment of cells with antioxidants such as N-acetylcysteine or Mn(III)tetrakis(4-benzoic acid)porphyrin chloride (MnTBAP, cell-permeable superoxide dismutase mimetic) rescued 6-OHDA- but not MPP+-induced cell death, whereas inclusion of catalase or NG-nitro-l-arginine had no effect in both cases. In addition, 6-OHDA induced ROS-mediated c-Jun N-terminal kinase (JNK) activation that was attenuated in the presence of N-acetylcysteine or MnTBAP but not catalase or Z-VAD-fmk. In contrast, MPP+ has little effect on JNK activity, indicating that ROS and/or ROS-induced cell death signaling pathway seems to play an essential role in 6-OHDA–mediated apoptosis but not in MPP+-induced necrosis in a mesencephalon-derived, dopaminergic neuronal cell line. J. Neurosci. Res. 57:86–94, 1999. © 1999 Wiley-Liss, Inc.

The Effect of Chronic Coffee Drinking on Blood Pressure: A Meta-Analysis of Controlled Clinical Trials

Abstract: We sought to assess the effect of coffee consumption on blood pressure in humans. Our data sources included a MEDLINE search of the literature published before December 1997, bibliography review, and expert consultation. We selected controlled trials in which coffee consumption was the only difference between the intervention and control groups, mean blood pressure change was reported for each group or period, and treatment lasted for >24 hours. Of 36 studies initially identified, 11 (522 participants) met these inclusion criteria. Information on sample size, study design, participant characteristics (gender, race, age, baseline blood pressure, and antihypertensive medications), and treatment results were abstracted by 3 reviewers using a standardized protocol. Treatment effect of coffee consumption on blood pressure was estimated with the use of a random-effects model. In the 11 trials, median duration was 56 days (range, 14 to 79 days), and median dose of coffee was 5 cups/d. Systolic and diastolic blood pressure increased by 2.4 (range, 1.0 to 3.7) mm Hg and 1.2 (range, 0.4 to 2.1) mm Hg, respectively, with coffee treatment compared with control. Multiple linear regression analysis identified an independent, positive relationship between cups of coffee consumed and subsequent change in systolic blood pressure, independent of age of study participants and study design characteristics. The effect of coffee drinking on systolic and diastolic blood pressure was greater in trials with younger participants. Our findings provide support for a relationship between coffee consumption and higher blood pressure. Trials of coffee cessation of longer duration and in persons with hypertension should be performed.

Lipid profiles in untreated patients with rheumatoid arthritis.

Abstract: OBJECTIVE: To investigate lipid profiles in patients with untreated active rheumatoid arthritis (RA) and to assess the relationship of the inflammatory condition of RA with lipid profiles. METHODS: Forty-two patients with RA and 42 age and sex matched healthy controls were studied. Patients with RA had not been treated with corticosteroid or disease modifying antirheumatic drugs prior to the study. Total cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol, apolipoprotein A1 (apo A1), apolipoprotein B (apo B), lipoprotein(a) [Lp(a)], and C-reactive protein (CRP) were measured in both groups. RESULTS: The levels of apo A1 and HDL-cholesterol were significantly lower in patients than in controls (128.5 vs. 151.8 mg/dl, 41.2 vs. 54.9 mg/dl, respectively). The level of Lp(a) was significantly higher in patients than in controls (27.1 vs. 18.0 mg/dl). The ratios of apo B/apo A1, total cholesterol/HDL-cholesterol, and LDL-cholesterol/HDL-cholesterol were significantly higher in patients than in controls (0.82 vs. 0.67, 4.4 vs. 3.4, 2.8 vs. 1.9, respectively). CRP showed a significant correlation with apo A1 (r = -0.44, p<0.01) and HDL-cholesterol (r = -0.35, p<0.05). CONCLUSION: Our study suggests that patients with untreated active RA have altered lipoprotein and apolipoprotein patterns that may possibly expose them to higher risk of atherosclerosis. The inflammatory condition of RA may affect the metabolism of HDL-cholesterol and apo A1.

Spectral Basis Neural Networks for Real-Time Travel Time Forecasting

Abstract: This paper examines how real-time information gathered as part of intelligent transportation systems can be used to predict link travel times for one through five time periods ahead (of 5-min duration). The study employed a spectral basis artificial neural network (SNN) that utilizes a sinusoidal transformation technique to increase the linear separability of the input features. Link travel times from Houston that had been collected as part of the automatic vehicle identification system of the TranStar system were used as a test bed. It was found that the SNN outperformed a conventional artificial neural network and gave similar results to that of modular neural networks. However, the SNN requires significantly less effort on the part of the modeler than modular neural networks. The results, of the best SNN were compared with conventional link travel time prediction techniques including a Kalman filtering model, exponential smoothing model, historical profile, and real-time profile. It was found that the SNN gave the best overall results.

Comparative study of transrectal ultrasonography, pelvic computerized tomography, and magnetic resonance imaging in preoperative staging of rectal cancer.

Abstract: PURPOSE: The preoperative assessment of rectal cancer wall invasion and regional lymph node metastasis is essential for the planning of optimal therapy. This study was done to determine the accuracy and clinical usefulness of transrectal ultrasonography, pelvic computed tomography, and magnetic resonance imaging in preoperative staging. METHODS: A total of 89 patients with rectal cancer were examined with transrectal ultrasonography (n=89), pelvic computed tomography (n=69), and magnetic resonance imaging with endorectal coil (n=73). The results obtained by these diagnostic modalities were compared with the histopathologic staging of specimens. RESULTS: In staging depth of invasion, the overall accuracy was 81.1 percent (72/89) by transrectal ultrasonography, 65.2 percent (45/69) by computed tomography, and 81 percent (59/73) by magnetic resonance imaging. Overstaging was 10 percent (9/89) by transrectal ultrasonography, 17.4 percent (12/69) by computed tomography, and 11 percent (8/73) by magnetic resonance imaging; and understaging was 8 of 89 (8.9 percent) by transrectal ultrasonography, 12 of 69 (17.4 percent) by computed tomography, and 6 of 73 (8 percent) by magnetic resonance imaging. In staging lymph node metastasis, the overall accuracy rate was 54 of 85 (63.5 percent) in transrectal ultrasonography, 39 of 69 (56.5 percent) in computed tomography, and 46 of 73 (63 percent) in magnetic resonance imaging. The sensitivity was 24 of 45 (53.3 percent) in transrectal ultrasonography, 14 of 25 (56 percent) in computed tomography, and 33 of 42 (78.5 percent) in magnetic resonance imaging; and specificity was 30 of 40 (75.0 percent) in transrectal ultrasonography, 25 of 44 (56.8 percent) in computed tomography, and 13 of 31 (41.9 percent) in magnetic resonance imaging. The accuracy in detection of positive lateral pelvic lymph nodes under magnetic resonance imaging (n=8) was 12.5 percent. The accuracy in detection of posterior vaginal wall invasion was 100 percent in transrectal ultrasonography (n=7) and 100 percent in magnetic resonance imaging (n=3), but 28.5 percent in computed tomography (n=7). CONCLUSIONS: Both transrectal ultrasonography and magnetic resonance imaging with endorectal coil exhibited similar accuracy and were superior to conventional computed tomography in preoperative assessment of depth of invasion and adjacent organ invasion. Because transrectal ultrasonography is a safer and more cost-effective modality than magnetic resonance imaging, transrectal ultrasonography is an appropriate method for preoperative staging of rectal cancer. Further efforts will be needed to provide a better staging of lymph node involvement.

Smoking and atherosclerotic cardiovascular disease in men with low levels of serum cholesterol the Korea Medical Insurance Corporation study

Abstract: ContextFew studies have examined the interactive effects of smoking and serum cholesterol level on morbidity and mortality from cardiovascular dieseases. In East Asia, where the prevalence of smoking is among the highest in the world, morbidity and mortality from ischemic heart disease (IHD) is rapidly escalating.ObjectivesTo determine whether cigarette smoking is an independent risk factor for atherosclerotic cardiovascular disease (ASCVD) in the Republic of Korea (South Korea), a population that has relatively low levels of serum cholesterol, and to determine whether serum cholesterol levels modify the risk relationship between smoking and ASCVD.DesignProspective cohort study with a follow-up period of 6 years (1993-1998).Setting and SubjectsA total of 106,745 Korean men aged 35 to 59 years who received health insurance from the Korea Medical Insurance Corporation and who had biennial medical evaluations in 1990 and 1992.Main Outcome MeasuresHospital admissions and deaths from IHD, cerebrovascular disease (CVD), and total ASCVD.ResultsAt baseline, 61,389 (58%) were current cigarette smokers and 64,482 (60%) had a total cholesterol level of less than 5.17 mmol/L (200 mg/dL). Between 1993 and 1998, 1006 IHD events (176 per 100,000 person-years), 1364 CVD events (238 per 100,000 person-years), and 716 other ASCVD events (125 per 100,000 person-years) occurred. In multivariate Cox proportional hazard models controlling for age, hypertension, hypercholesterolemia, and diabetes, current smoking increased the risk of IHD (risk ratio [RR], 2.2; 95% confidence interval [CI], 1.8-2.8), CVD (RR, 1.6; 95% CI, 1.4-1.8), and total ASCVD (RR, 1.6; 95% CI, 1.5-1.8). For each outcome, there were significant dose-response relationships with amount and duration of smoking. Throughout the range of serum cholesterol levels, current smoking significantly increased the risk of IHD and CVD. In the lowest quartile of serum cholesterol levels (<4.42 mmol/L [171 mg/dL]), the RR from current smoking was 3.3 (95% CI, 1.7-6.2) for IHD and 1.6 (95% CI, 1.2-2.3) for CVD. There was no evidence of an interaction between smoking and serum cholesterol (P for interaction = .75, .87, and .92 for IHD, CVD, and total ASCVD, respectively).ConclusionsThis study demonstrates that in Korea smoking is a major independent risk factor for IHD, CVD, and ASCVD and that a low cholesterol level confers no protective benefit against smoking-related ASCVD.

The Effects of Aerobic Exercise and T'ai Chi on Blood Pressure in Older People: Results of a Randomized Trial

Abstract: OBJECTIVE: To compare the effects on blood pressure of a 12-week moderate-intensity aerobic exercise program and a T'ai Chi program of light activity. DESIGN: A randomized clinical trial. SETTING: A suburban clinic in the Baltimore, MD, area. PARTICIPANTS: Sixty-two sedentary older adults (45% black, 79% women, aged > 60 years) with systolic blood pressure 130–159 mm Hg and diastolic blood pressure < 95 mm Hg (not on antihypertensive medication). INTERVENTION: Participants were randomized to a 12-week aerobic exercise program or a light intensity T'ai Chi program. The goal of each condition was to exercise 4 days per week, 30 minutes per day. MEASUREMENTS: Blood pressure was measured during three screening visits and every 2 weeks during the intervention. Estimated maximal oxygen uptake and measures of physical activity level were determined at baseline and at the end of the intervention period. RESULTS: Mean (SD) baseline systolic and diastolic blood pressures were 139.9 (9.3) mm Hg and 76.0 (7.3) mm Hg, respectively. For systolic blood pressure, adjusted mean (SE) changes during the 12-week intervention period were −8.4 (1.6) mm Hg and −7.0 (1.6) mm Hg in the aerobic exercise and T'ai Chi groups, respectively (each within-group P < .001; between-group P = .56). For diastolic blood pressure, corresponding changes were −3.2 (1.0) mm Hg in the aerobic exercise group and −2.4 (1.0) mm Hg in the T'ai Chi group (each within-group P < .001; between-group P = .54). Body weight did not change in either group. Estimated maximal aerobic capacity tended to increase in aerobic exercise (P = .06) but not in T'ai Chi (P = .24). CONCLUSIONS: Programs of moderate intensity aerobic exercise and light exercise may have similar effects on blood pressure in previously sedentary older individuals. If additional trials confirm these results, promoting light intensity activity could have substantial public health benefits as a means to reduce blood pressure in older aged persons.

Periodontal repair in dogs: effect of rhBMP-2 concentration on regeneration of alveolar bone and periodontal attachment.

Abstract: The objective of this study was to evaluate the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) concentration on regeneration of alveolar bone and cementum, and on associated root resorption and ankylosis. Contralateral, critical size, supra-alveolar, periodontal defects were surgically produced and immediately implanted with rhBMP-2 in an absorbable collagen sponge (ACS) carrier in 8, young adult, male, beagle dogs. 6 animals received rhBMP-2/ACS (rhBMP-2 at 0.05, 0.10, or 0.20 mg/mL; total construct volume/defect approximately 4.0 mL) in contralateral defects following an incomplete block design. 2 animals received rhBMP-2/ACS (rhBMP-2 at 0 and 0.10 mg/mL) in contralateral defects (controls). The animals were euthanised at 8 weeks post-surgery and block sections of the defects were collected for histologic and histometric analysis. Supra-alveolar periodontal defects receiving rhBMP-2 at 0.05, 0.10, or 0.20 mg/ml exhibited extensive alveolar regeneration comprising 86%, 96%, and 88% of the defect height, respectively. Cementum regeneration encompassed 8%, 6%, and 8% of the defect height, respectively. Root resorption was observed for all rhBMP-2 concentrations. Ankylosis was observed in almost all teeth receiving rhBMP-2. Control defects without rhBMP-2 exhibited limited, if any, evidence of alveolar bone and cementum regeneration, root resorption, or ankylosis. Within the selected rhBMP-2 concentration and observation interval, there appear to be no meaningful differences in regeneration of alveolar bone and cementum. There also appear to be no significant differences in the incidence and extent of root resorption and ankylosis, though there may be a positive correlation with rhBMP-2 concentration.

Top-down and bottom-up attentional control : On the nature of interference from a salient distractor

Abstract: In two experiments using spatial probes, we measured the temporal and spatial interactions between top-down control of attention and bottom-up interference from a salient distractor in visual search. The subjects searched for a square among circles, ignoring color. Probe response times showed that a color singleton distractor could draw attention to its location in the early stage of visual processing (before a 100-msec stimulus onset asynchrony [SOA]), but only when the color singleton distractor was located far from the target. Apparently the bottom-up activation of the singleton distractor's location is affected early on by local interactions with nearby stimulus locations. Moreover, probe results showed that a singleton distractor did not receive attention after extended practice. These results suggest that top-down control of attention is possible at an early stage of visual processing. In the long-SOA condition (150-msec SOA), spatial attention selected the target location over distractor locations, and this tendency occurred with or without extended practice.

Fas ligand and Fas are expressed constitutively in human astrocytes and the expression increases with IL-1, IL-6, TNF-alpha, or IFN-gamma.

Abstract: Fas ligand (FasL) and Fas are mediators of apoptosis, which are implicated in the peripheral deletion of autoimmune cells, activation-induced T cell death, and cytotoxicity mediated by CD8+ T cells. Fas is also believed to be involved in several central nervous system diseases, but until now, the effector cells expressing FasL in the brain have not been identified. We investigated the expression levels of Fas and FasL with the stimulation of cytokines and the possible effector cells targeting Fas-bearing cells. Our data demonstrated that: 1) FasL is expressed constitutively on astrocytes taken from a fetus or an adult and that its expression increases when these cells are treated with IL-1, IL-6, or TNF-α in which the pretreatment of IFN-γ triggers astrocytes to express more FasL; 2) astrocytes induce apoptosis in MOLT-4 cells through FasL; 3) Fas is also expressed constitutively and is up-regulated by IL-1, IL-6, or TNF-α in which the pretreatment of IFN-γ triggers astrocytes to express more Fas; 4) apoptosis occurs when fetal astrocytes are treated with agonistic anti-Fas IgM Ab after culture with IFN-γ and TNF-α; and 5) TNF-related apoptosis inducing ligand is up-regulated in fetal astrocytes with stimuli of IL-1 or TNF-α. These findings suggest a possible role of astrocytes in the induction of apoptosis in central nervous system diseases.

On compensating nonlinear distortions of an OFDM system using an efficient adaptive predistorter

Abstract: This paper presents an efficient adaptive predistortion technique compensating for nonlinear distortions caused by a high-power amplifier (HPA) cascaded with a linear filter in an OFDM system. In the proposed approach, the memoryless HPA, preceded by a linear filter with memory in OFDM systems, is modeled by the Wiener system, which is then precompensated by the proposed adaptive predistorter with a minimum number of filter taps. It is confirmed by computer simulation that the proposed approach produces a faster convergence speed than the previous adaptive predistortion technique, and provides a small output backoff as low as 5.5 dB for an OFDM system employing an HPA with a linear filter.

Inactivation Kinetics of Lactobacillus plantarum by High Pressure Carbon Dioxide

Abstract: Inactivation kinetics of Lactobacillus plantarum by high pressure CO 2 was investigated to understand the mechanism of microbial inactivation. The inactivation rates increased with pressure, temperature and exposure time, and with decreasing pH of media. Microbial inactivation was governed essentially by penetration of CO 2 into cells and its effectiveness could be improved by the enhanced transfer rate. Microbial reduction of 8 log cycles was observed within 120 min under CO 2 pressure of 70 kg/cm 2 at 30°C. We hypothesized that the cell death resulted from the lowered intracellular pH and damage to the cell membrane due to penetration of CO 2 . Pressurized CO 2 treatment is a potential nonthermal technology for food preservation.

Reanalysis of the effects of air pollution on daily mortality in Seoul, Korea: A case-crossover design.

Abstract: We used the case-crossover design to identify any increase in mortality in Seoul, Korea, when there were higher levels of ambient air pollution on case-days than would be expected solely as a result of chance. This empirical study showed that either unidirectional retrospective (selecting only control days prior to death) or prospective (selecting only control days after death) control sampling could cause risk estimates to be confounded by seasonal waves as well as time trends in air pollution levels. In bidirectional control sampling in which exposures at death were compared with exposures both before and after death, the estimated mortality was resistant to confounding by time patterns of air pollution. Using a bidirectional control sampling approach, the results from a conditional logistic regression model controlling for weather conditions showed that the nonaccidental mortality associated with a 50-ppb increment over a 3-day moving average of SO(2) concentrations, including the concurrent day and preceding 2 days, was 1.023 [95% confidence interval (CI), 1.016-1.084]. The relative risk of death was 1.023 (CI, 0.999-1.048) per 50 ppb for 1-hr maximum O(3) and 1.010 (CI, 0.988-1.032) per 100 microg/m(3 )or total suspended particulates. In conclusion, the findings of this study were 2-fold: given the consistency of the observed association between SO(2) and daily mortality across different analysis methods, the association reported here indicates that air pollution is a probable contributor to premature death; and bidirectional control sampling is needed in a case-crossover design applied to air pollution epidemiologic studies to control confounding by seasonal patterns of air pollution as well as time trends.