Induction Motor Fault Diagnosis Using Support Vector Machine, Neural Networks, and Boosting Methods.

Induction motors are robust and cost effective; thus, they are commonly used as power sources in various industrial applications. However, due to the characteristics of induction motors, industrial processes can stop when motor failures occur. Thus, research is required to realize the quick and accurate diagnosis of faults in induction motors. In this study, we constructed an induction motor simulator with normal, rotor failure, and bearing failure states. Using this simulator, 1240 vibration datasets comprising 1024 data samples were obtained for each state. Then, failure diagnosis was performed on the acquired data using support vector machine, multilayer neural network, convolutional neural network, gradient boosting machine, and XGBoost machine learning models. The diagnostic accuracies and calculation speeds of these models were verified via stratified K-fold cross validation. In addition, a graphical user interface was designed and implemented for the proposed fault diagnosis technique. The experimental results demonstrate that the proposed fault diagnosis technique is suitable for diagnosing faults in induction motors.

Eight-week supplementation of Aronia berry extract promoted the glutathione defence system against acute aerobic exercise-induced oxidative load immediately and 30 min post-exercise in healthy adults: a double-blind, randomised controlled trial.

BACKGROUND: Food antioxidants have received prompt attention for controlling oxidative stress encountered in daily life. This study aimed to examine the protective effects of Aronia berry extract (ABE) supplementation on acute aerobic exercise (AAE)-induced oxidative stress in healthy subjects. METHODS: We assessed a battery of antioxidant defence and oxidative stress parameters at pre-exercise, immediately post-exercise and 30 min post-exercise in healthy middle-aged adults with habitually low intakes of fruit and vegetables in an 8-week, double-blind, randomised, controlled clinical trial with two arms (n = 70). The AAE challenge model, characterised as a treadmill exercise for 30 min at 60% VO2 maximum, was applied to load oxidative stress at the end of the study. Pearson's correlation analysis assessed the association between the changes in antioxidant defence capacities and oxidative stress levels. RESULTS: The time-course-dependent oxidative stress was well observed in the placebo group regarding the glutathione peroxidase (GPx) activity and the reduced glutathione (GSH) availability for antioxidant defence and erythrocyte malondialdehyde, interleukin-6 and lactate levels for oxidative damage. Meanwhile, the ABE supplementation effectively strengthened the glutathione defence system by increasing GSH availability and GPx activity immediately post-exercise and 30 min post-exercise. In addition, the scatter plot and linear regression analysis revealed strong negative correlations of GSH availability with oxidised low-density lipoprotein and plasma malonaldehyde levels. CONCLUSION: These findings suggest that daily supplementation of 300 mg ABE might help boost GSH levels and an adaptive antioxidant enzyme defence system of erythrocytes in healthy adults with habitually low fruit and vegetable intakes.

Estimation of Online State of Charge and State of Health Based on Neural Network Model Banks Using Lithium Batteries.

Lithium batteries are secondary batteries used as power sources in various applications, such as electric vehicles, portable devices, and energy storage devices. However, because explosions frequently occur during their operation, improving battery safety by developing battery management systems with excellent reliability and efficiency has become a recent research focus. The performance of the battery management system varies depending on the estimated accuracy of the state of charge (SOC) and state of health (SOH). Therefore, we propose a SOH and SOC estimation method for lithium-ion batteries in this study. The proposed method includes four neural network models-one is used to estimate the SOH, and the other three are configured as normal, caution, and fault neural network model banks for estimating the SOC. The experimental results demonstrate that the proposed method using the long short-term memory model outperforms its counterparts.

The Effect of Mind Subtraction Meditation Intervention on Smartphone Addiction and the Psychological Wellbeing among Adolescents.

As the smartphone has become an indispensable device in modern lives, consequential psychosocial problems such as smartphone addiction have been getting attention worldwide, especially regarding adolescents. Based on its positive effect on young individuals' mental health, mind subtraction meditation has been widely applied to many school-based programs in South Korea. This study aims to identify the effects of a school program based on mind subtraction on the smartphone addiction of adolescents. A total of 49 high school sophomores, 24 from the experimental group (mean age = 16), and 25 from the control group (mean age = 16) are included in this case-control study. The experimental group is given the meditation program sessions in the morning, two times a week for 20 min per session, for a total of 12 weeks. The experimental group shows improvements regarding the 'smartphone addiction' section (p < 0.001), for instant satisfaction (p < 0.001) and long-term satisfaction (p < 0.001). Concerning the 'self-control' section and decreasing stress (p < 0.001), problem focusing (p < 0.001), and social support navigation (p = 0.018), there are improvements in these 'stress coping strategies' sections. This study directly shows the positive effect of mind subtraction meditation on smartphone addiction in adolescents and, thus, provides guidance to the future development of smartphone addiction prevention programs for young individuals.

Prophylactic Administration of Vector-Encoded Porcine Granulocyte-Colony Stimulating Factor Reduces Salmonella Shedding, Tonsil Colonization, and Microbiota Alterations of the Gastrointestinal Tract in Salmonella-Challenged Swine.

Salmonella colonization of food animals is a concern for animal health and public health as a food safety risk. Various obstacles impede the effort to reduce asymptomatic Salmonella carriage in food animals, including the existence of numerous serovars and the ubiquitous nature of Salmonella. To develop an intervention strategy that is non-specific yet effective against diverse Salmonella serovars, we explored the prophylactic use of a cytokine to decrease Salmonella in swine by boosting the host's innate immune system. Granulocyte-colony stimulating factor (G-CSF) is the major cytokine regulating the production, differentiation, function, and survival of neutrophils. Neutrophils play a critical role in the response to Salmonella; therefore, we evaluated the vectored-delivery of porcine G-CSF as a prophylactic to reduce Salmonella in pigs. Crossbred pigs, 5 weeks of age, were intramuscularly injected with a replication-defective human adenovirus (Ad5) engineered to express porcine G-CSF (Ad5-G-CSF, n = 9). Control pigs received the same Ad5 vector lacking the gene encoding G-CSF (Ad5-empty, n = 7). Four days later, all pigs (n = 16) were intranasally inoculated with 1 × 10(7) colony forming unit (CFU) of Salmonella enterica serovar Typhimurium UK1. At 2 and 3 days post-challenge with Salmonella, Ad5-G-CSF-treated pigs shed significantly less Salmonella (~10(3) CFU/g) in their feces than Ad5-empty-treated pigs (~10(4)-10(5) CFU/g; P < 0.05). A significant 4-log reduction in tonsil colonization was also observed in the Ad5-G-CSF-treated pigs at 7 days post-challenge (P < 0.05). In the gastrointestinal tract, the Peyer's patch region of the ileum exhibited a significant 0.5-log reduction in colonization in the Ad5-G-CSF-treated pigs (P < 0.05). The microbiota of all challenged pigs was assessed by sequencing and analyzing the V1-V3 region of the 16S rRNA gene from fecal DNA samples. The microbial community structure of Salmonella-challenged pigs was less disturbed post-challenge in the Ad5-G-CSF-treated pigs than the Ad5-empty-treated pigs. This suggests that Ad5-G-CSF administration mitigated changes in the microbial community structure caused by Salmonella challenge. Collectively, these data suggest that delivery of a targeted immunostimulant to enhance neutropoiesis may be a strategy to reduce Salmonella colonization, potentially during periods of immunological stress.

Layer-specific analysis of dobutamine stress echocardiography for the evaluation of coronary artery disease.

Although dobutamine stress echocardiography (DSE) is a well-defined tool for the diagnosis of coronary artery disease (CAD), false-negative and false-positive results still occur. This study investigated the diagnostic role of layer-specific analysis using 2-dimensional speckle-tracking echocardiography (STE) during DSE.A total of 121 patients who underwent DSE and showed normal wall motion and ejection fraction during baseline echocardiography were enrolled. All patients underwent coronary angiography after DSE within 2 weeks. The patients were divided into the following 4 groups according to DSE results and CAD status: negative DSE with no significant CAD (n = 73), positive DSE with significant CAD (n = 16), negative DSE with significant CAD (n = 17), and positive DSE with no significant CAD (n = 15). Layer-specific global longitudinal strain (GLS) was assessed in the endocardium, mid-myocardium, and epicardium by STE techniques.Patients with significant CAD were older, more male and showed higher glucose level compared to patients without CAD. But coronary risk factors and previous medications were not different between patients with and without CAD. There were no significant differences in whole myocardium or layer-specific GLS found in the baseline echocardiography. During recovery echocardiography, endocardial GLS was significantly different between patients with and without CAD, regardless of the DSE results. A receiver-operating characteristic curve analysis showed that endocardial GLS (>-16%) was superior for identifying significant CAD during the DSE recovery stage. Diagnostic accuracy was improved by applying the results of endocardial GLS compared with visual estimation of DSE.The assessment of layer-specific strain by STE during DSE was feasible, and the evaluation of poststress endocardial function is a more sensitive tool for the detection of CAD.

The Effects of Mind Subtraction Meditation on Depression, Social Anxiety, Aggression, and Salivary Cortisol Levels of Elementary School Children in South Korea.

This study analyzed the effects of a school-based mind subtraction meditation program on depression, social anxiety, aggression, and salivary cortisol levels of 42 elementary school children in South Korea. The research design was a nonequivalent group comparison with pretest and post-test. The experimental group was given 8weeks of the meditation program. The results showed social anxiety, aggression, and salivary cortisol levels were significantly lowered in the experimental group. This demonstrated that the school-based mind subtraction meditation program could be effective in improving psychosocial and behavioral aspects of mental health in elementary school children.

Injuries associated with the 580 km university student grand voluntary road march: focus on foot injuries.

College student volunteers (n = 142) completed a 580 km road march for 21 consecutive days. Each volunteer carried a backpack that weighed 14.1 ± 1.4 kg on the average. We investigated the incidence and location of blisters associated with the road march using a foot map along with other injuries. Overall, 95.1% of the subjects (135 of 142) sustained one or more injuries. All injured subjects had foot blisters, and 18% had other foot injuries. The most common locations of blister development were the right 5th toe (61%) and the left 5th toe (57%). The little toes seem to have been subjected to the greatest friction and shearing forces. March-related injuries, excluding foot injuries, were ankle pain (12.7%), knee pain (12.7%) and Achilles tendon pain (7.7%). Six subjects (4.2%) needed extra medical treatment for more than 2 weeks prior to returning to their daily lives after completion of the march due to associated injuries. The present study observed a very high incidence rate of injuries (95.1%) associated with the 580 km university students grand road march. These injuries posed an obstacle against completion of the road march and against returning to daily life. Active preventive interventions such as physical therapy and customized reinforced shoes and education program are recommended for reducing incidence rate and severity of injuries.

Omentum Cells Promote Healing of Colonic Tissues in Dextran Sulfate Sodium (DSS) Induced Model of Colitis in Mice.

BACKGROUND: Inflammatory bowel disease is characterized by persistent inflammation of the intestinal tissues. Although the usage of biologics has greatly enhanced the management of this disorder, a permanent treatment does not exist. In this study, we investigated whether the cells with anti-inflammatory and healing properties from the omentum could be harnessed to treat colitis in dextran sulfate sodium (DSS)-induced mouse colitis model. METHODS: C57BL/6 mice were administered 2% DSS for 10 days and then injected in the peritoneum with cells isolated from the murine omentum. Thereafter, body weight change, serum KC levels, and histological analysis of the colon were conducted. We also examined if omentum infused mice were resistant to a lethal challenge of 4% DSS. RESULTS: 2% DSS-mice injected with omentum cells exhibited a decrease in body weight loss, decreased inflammation in the colon and decreased levels of the inflammatory cytokine KC in the serum compared to mice given 2% DSS alone. In addition, mice administered a lethal dose of 4% DSS exhibited a 50% decrease in mortality when injected with omentum cells. CONCLUSION: Cells from the omentum exert anti-inflammatory and/or healing properties in the acute DSS-induced colitis model.

Effect of three weeks of continuous positive airway pressure treatment on mood in patients with obstructive sleep apnoea: a randomized placebo-controlled study.

BACKGROUND: Patients with obstructive sleep apnoea (OSA) commonly have mood symptoms such as depression and anxiety. However, the results of randomized controlled trials on the therapeutic effect of CPAP on mood symptoms have been inconsistent. The present study examined whether three weeks of CPAP treatment had specific therapeutic effects on mood symptoms in patients with OSA compared with placebo. METHODS: A double-blind, parallel, randomized controlled trial using therapeutic and placebo CPAP was performed in 71 patients newly diagnosed with OSA (apnoea-hypopnoea index [AHI]⩾10). Mood was assessed by the Center for Epidemiologic Studies-Depression (CES-D) Scale, the Profile of Mood States (POMS), and the Brief Symptom Inventory (BSI) before and after three weeks of treatment. AHI was used to assess the severity of apnoea. The two groups were compared using a simple comparison of the changes within each arm and repeated measures analysis of variance. RESULTS: Fifty-six subjects completed the study: 26 in the CPAP group and 30 in the placebo group. The two groups were well matched at baseline, with no significant differences in demographic, mood and apnoea variables. Both groups had severe apnoea, mild depression, and anxiety at baseline. After three weeks of treatment, AHI decreased significantly in the CPAP group. The mean change in AHI was -30.7 (standard deviation [SD] 23.1) in the CPAP group and -5.8 (SD 18.3) in the placebo group (difference between groups P<0.001). However, after three weeks of treatment, there were no significant time by treatment effects in relation to mood, as assessed by the CES-D, POMS Depression, POMS Tension, BSI Depression, or BSI Anxiety (all P>0.05). CONCLUSION: In conclusion, three weeks of CPAP treatment did not show a specific therapeutic effect on mood symptoms in patients with OSA.

A Model for Studying Neuropsychological Effects of Sleep Intervention: The Effect of 3-week Continuous Positive Airway Pressure Treatment.

PURPOSE: Patients with obstructive sleep apnea (OSA) commonly have cognitive complaints. There are few randomized studies that have examined neuropsychological effects of continuous positive airway pressure (CPAP) treatment in patients with OSA. In this double-blind trial, we examined if a 3-week CPAP treatment compared with placebo CPAP treatment has specific therapeutic effects on cognitive impairments in patients with OSA and if there are specific domains of cognitive impairments sensitive to 3-week CPAP treatment. SUBJECTS AND METHODS: Thirty-eight newly diagnosed patients with untreated OSA underwent neuropsychological testing before and after 3-weeks CPAP or Placebo CPAP treatment. The two treatment groups (therapeutic CPAP, and placebo-CPAP) were compared using repeated measures analysis of variance (ANOVA). RESULTS AND CONCLUSION: Impairments in neuropsychological functioning ranged from 2.6% to 47.1% before treatment. In response to 3 weeks of treatment, there was no significant time by treatment interaction for a global deficit score of neuropsychological functioning. Only the Stroop Color (number correct) test showed significant improvement specific to CPAP treatment. The study demonstrates the importance of further randomized placebo controlled studies in this area.

The Relationship between psychomotor vigilance performance and quality of life in obstructive sleep apnea.

OBJECTIVE: Patients with obstructive sleep apnea (OSA) commonly have cognitive complaints, particularly in attention, and report decreased quality of life. We examined how vigilance and sustained attention, as assessed by the Psychomotor Vigilance Task (PVT), were related to quality of life after controlling for apnea severity and depression in subjects with OSA. SUBJECTS AND METHODS: Fifty-seven patients with newly diagnosed and untreated OSA had their sleep monitored with polysomnography. Quality of life was assessed by the Short Form-36 health survey questionnaire (SF-36). Mood was assessed by the Center for Epidemiologic Studies-Depression (CES-D) Scale. After sleep monitoring and psychological assessments were performed, the 10-minute PVT was administered. The main outcome variables were PVT lapse count and average response time (RT). Simple correlations and multiple linear regression were used to examine the association between PVT performance and age, body mass index, sleep variables, apnea hypopnea index, oxygen desaturation index, and CES-D. RESULTS AND CONCLUSION: Both the PVT lapse count and RT were significantly associated with the SF-36 physical component summary score (PCS). In multiple linear regression, PVT RT was an independent predictor of the SF-36 PCS (full model R(2) = 0.331, p = 0.003). PVT lapse was also an independent predictor of the SF-36 PCS (full model R(2) = 0.320, p = 0.004). However, neither PVT RT nor lapse was a significant independent predictor of the SF-36 mental component summary score (MCS). Only CES-D was an individual predictor of the SF-36 MCS (ß = -0.676, p < 0.001). Impairments in sustained attention and vigilance may underlie the limitations in physical health-related quality of life reported by people with OSA, even after controlling for demographic variables, apnea severity, and depression.

Number of lapses during the psychomotor vigilance task as an objective measure of fatigue.

PURPOSE: This study examined how well the Psychomotor Vigilance Task (PVT) performance was related to subjective measures of fatigue. In order to study subjects presenting with a wide range of fatigue symptoms, we studied healthy individuals as well as patients with varying severity of obstructive sleep apnea. We also examined if the PVT/fatigue relationship could be influenced by depressive symptoms. SUBJECTS AND METHODS: Forty-eight participants had their sleep monitored with polysomnography. Fatigue was assessed by Multidimensional Fatigue Symptom Inventory-short form (MFSI-sf). Depressed mood was assessed by the Center for Epidemiologic Studies-Depression (CES-D) Scale. After sleep monitoring and psychological assessments, the 10-minute PVT was administered. The main outcome variable was the PVT lapse count. Simple correlations and hierarchical linear regression were used to examine the association between age, body mass index (BMI), sleep variables, apnea hypopnea index (AHI), oxygen desaturation index (ODI), CES-D, fatigue, and PVT. RESULTS AND CONCLUSION: The PVT lapse count was significantly associated with MFSI-sf physical fatigue (r = 0.324, p = 0.025). In hierarchical regression (full model R2 = 0.256, p = 0.048), higher BMI (p = 0.038), and higher MFSI-sf physical fatigue (p= 0.040) were independent predictors of the PVT lapse count. Age, AHI, ODI, and CES-D were unrelated to the PVT lapse count. In conclusion, the findings suggest that even after controlling for age, BMI, depression, and apnea severity, physical fatigue is associated with the PVT lapse.

Platelet serotonin transporter function and heart rate variability in patients with panic disorder.

Many studies showed abnormal serotonin transporter (5-HTT) function and heart rate variability (HRV) in panic disorder patients. The present study investigated the relationship between HRV power spectral analysis findings and platelet serotonin uptake in panic disorder patients. Short-term HRV over 5 min and platelet serotonin transporter uptake parameters (V(max) and K(m)) were measured both in 45 patients with panic disorder and in 30 age-matched normal healthy control subjects. Low frequency power (LF) normalized unit (nu) and LF/high frequency power (HF) were significantly higher, whereas HF and HF nu were lower in the patient group than in the control group. V(max) and K(m) were all significantly lower (i.e., reflects decreased 5-HTT function) in patients with panic disorder than in normal controls. In the patient group, K(m) was negatively correlated with LF/HF and LF nu whereas no such correlations between them were found in the control group. By multivariate analysis based on multiple hierarchical linear regression, a low K(m) independently predicted an increased LF nu even after controlling for age, sex, and body mass index in the patient group. These results suggest that impaired 5-HTT function is closely related to dysregulation of autonomic nervous system in panic disorder.

Platelet serotonin transporter function after short-term paroxetine treatment in patients with panic disorder.

Dysfunctions in serotonin neurotransmission have been implicated in some psychiatric disorders, and in particular, altered serotonin transporter function has been noted in panic disorder. In this study, the authors compared platelet [(3)H]serotonin uptake parameters, including maximum velocities (V(max)) and affinity constants (K(m)), in patients with panic disorder not undergoing treatment (n=21) and in healthy subjects (n=20). V(max) and K(m) values were re-examined after 12 weeks of paroxetine treatment. Values of V(max) and K(m) were lower in panic disorder patients at baseline than in healthy subjects. After treatment, K(m) normalized in panic patients, whereas V(max) did not change. A significant inverse correlation was found between increased K(m) and changes in anxiety levels. These results support a hypothesis of serotonergic transporter abnormalities in panic disorder, and suggest that increased K(m) values of platelet serotonin transporters parallel clinical improvement after short-term pharmacotherapy in panic disorder.

Mirtazapine versus venlafaxine for the treatment of somatic symptoms associated with major depressive disorder: a randomized, open-labeled trial.

Somatic symptoms are often important in the treatment of major depressive disorder (MDD). The aim of this open-labeled trial was to examine the efficacy of mirtazapine for the treatment of MDD with clinically significant somatic symptoms, as compared with venlafaxine. A total of 126 patients with MDD (score >/=18 on the Hamilton Rating Scale for Depression-17) were included in both the intent-to-treat (n=73 in the mirtazapine group and n=53 in the venlafaxine group) and completer analysis (n=51 and n=37, respectively). After treatment, both treatment groups showed similar improvements in depressive symptoms. Repeated measures analysis of variance for the intent-to-treat population revealed that there were no significant differences in mean change of the Symptom Check List-90-Revised (SCL-90-R) somatization subscores between the two groups. For completers, there was a significant timextreatment interaction in the SCL-90-R somatization subscores, but the differences between the two groups at endpoint did not reach statistical significance in post-hoc analysis. In conclusion, this study suggests that overall efficacies of mirtazapine and venlafaxine are similar for the treatment of overall symptoms in MDD, and both drugs may be useful for the treatment of somatic symptoms in MDD patients.

Iron regulated genes of Salmonella enterica serovar Typhimurium in response to norepinephrine and the requirement of fepDGC for norepinephrine-enhanced growth.

Catecholamines may stimulate enteric bacteria including the foodborne pathogen Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) by two mechanisms in vivo: as a quorum sensing signal and a supplier of iron. To identify genes of Salmonella Typhimurium that respond to norepinephrine, transposon mutagenesis and DNA microarray analysis were performed. Insertional mutations in the following genes decreased norepinephrine-enhanced growth: degS, entE, entF, fes, gpmA, hfq, STM3846. DNA microarray and real-time RT-PCR analyses revealed a decrease in the expression of several genes involved in iron acquisition and utilization during norepinephrine exposure, signifying the iron-limiting conditions of serum-SAPI minimal medium and the siderophore-like activity of norepinephrine. Unlike the wild-type parent strain, growth of neither a fepA iroN cirA mutant nor a fepC mutant, harboring deletional mutations in the outer and inner membrane transporters of enterochelin, respectively, was enhanced by norepinephrine. However, growth of the fepC and the fepA iroN cirA mutants could be rescued by an alternative siderophore, ferrioxamine E, further validating the role of norepinephrine in supplying the organism with iron via the catecholate-specific iron transport system. Contrary to previous reports using small animal models, the fepA iroN cirA mutant of Salmonella Typhimurium colonized the swine gastrointestinal tract, as did the fepC mutant.

beta-adrenoceptor affinity as a biological predictor of treatment response to paroxetine in patients with acute panic disorder.

BACKGROUND: Few studies have reported on the functional differences of the beta-adrenoceptor between treatment responders and non-responders in panic disorder (PD). The aim of this study was to compare the nature of the beta-adrenoceptor function and clinical variables between treatment responders and non-responders to paroxetine treatment in acute PD patients. METHOD: Paroxetine was administered to all of the panic patients for 12 weeks. The lymphocyte beta-adrenoceptor density (Bmax), affinity (1/Kd), and sensitivity (cAMP ratio) were measured in 22 untreated outpatients with acute PD and 22 age, sex and BMI matched control subjects. Psychological assessments were conducted using the HAM-A, and HAM-D, STAI-S and STAI-T, Anxiety sensitivity index (ASI), and Acute panic inventory (API). RESULTS: A significantly higher Kd was observed in the panic patients before treatment as compared with the control subjects, but there was no significant difference in Kd between the panic patients and control subjects after the treatment. Among the 22 patients, the 11 treatment responders (50%) showed a significantly higher Kd and lower mean scores of HAM-D, STAI-S, STAI-T, and ASI at baseline, compared with the non-responders. Logistic regression revealed that the pretreatment Kd and HAM-D were significantly reliable predictors for treatment response (p<0.05). CONCLUSION: The beta-adrenoceptor affinity (1/Kd) was decreased and adaptively normalized after treatment with paroxetine in the acute panic patients. In addition, a low pretreatment beta-adrenoceptor affinity (1/Kd) was found to predict the treatment response and can be suggested as a biological predictor of treatment response in acute PD.

Evaluation of phoP and rpoS mutants of Salmonella enterica serovar Typhi as attenuated typhoid vaccine candidates: virulence and protective immune responses in intranasally immunized mice.

The attenuation and immunoenhancing effects of rpoS and phoP Salmonella enterica serovar strain Typhi (Salmonella typhi) mutants have not been compared. Here, three S. typhi deletion mutants (phoP, rpoS, and rpoS-phoP double mutant) are constructed and these mutants are characterized with respect to invasiveness, virulence, and protective immune response compared with wild-type Ty2. It was found that phoP and phoP-rpoS deletion mutants are less invasive to HT-29 cells than the wild-type Ty2 and the rpoS single-deleted strain. The LD(50) of immunized mice was higher for phoP than for rpoS mutants, and the highest for the phoP-rpoS double mutant. In addition, all S. typhi mutants showed an increase in the specific serum IgG levels and T-cell-mediated immunity, and showed equal protection abilities against a wild-type Ty2 challenge after two rounds of immunization in BALB/c mice. It is concluded that phoP genes appear to play a more important role than rpoS genes in both cellular invasion and virulence of S. typhi, but not in immunogenicity in mice. Furthermore, the data indicate that the phoP-rpoS double mutant may show promise as a candidate for an attenuated typhoid vaccine.

Cobalt chloride-induced apoptosis and extracellular signal-regulated protein kinase 1/2 activation in rat C6 glioma cells.

Brain ischemia brings about hypoxic insults. Hypoxia is one of the major pathological factors inducing neuronal injury and central nervous system infection. We studied the involvement of mitogen-activated protein (MAP) kinase in hypoxia-induced apoptosis using cobalt chloride in C6 glioma cells. In vitro cytotoxicity of cobalt chloride was tested by MTT assay. Its IC(50) value was 400 microM. The DNA fragment became evident after incubation of the cells with 300 microM cobalt chloride for 24 h. We also evidenced nuclear cleavage with morphological changes of the cells undergoing apoptosis with electron microscopy. Next, we examined the signal pathway of cobalt chloride-induced apoptosis in C6 cells. The activation of extracellular signal-regulated protein kinase 1/2 (ERK 1/2) started to increase at 1 h and was activated further at 6 h after treatment of 400 M cobalt chloride. In addition, pretreatment of PD98059 inhibited cobalt chloride-induced apoptotic cell morphology in Electron Microscopy. These results suggest that cobalt chloride is able to induce the apoptotic activity in C6 glioma cells, and its apoptotic mechanism may be associated with signal transduction via MAP kinase (ERK 1/2).