Resistive wall mode instability at intermediate plasma rotation

Experimental observation of resistive wall mode (RWM) instability in the National Spherical Torus Experiment (NSTX) at plasma rotation levels intermediate to the ion precession drift and ion bounce frequencies suggests that low critical rotation threshold models are insufficient. Kinetic modifications to the ideal stability criterion yield a more complex relationship between plasma rotation and RWM stability. Good agreement is found between an experimental RWM instability at intermediate plasma rotation and the RWM marginal point calculated with kinetic effects included, by the MISK code. By self-similarly scaling the experimental plasma rotation profile and the collisionality in the calculation, resonances of the mode with the precession drift and bounce frequencies are explored. Experimentally, RWMs go unstable when the plasma rotation is between the stabilizing precession drift and bounce resonances.

Effects of n-3 Polyunsaturated Fatty Acid Therapy on Plasma Inflammatory Markers and N-Terminal Pro-brain Natriuretic Peptide in Elderly Patients with Chronic Heart Failure

Several previous studies have suggested that n-3 polyunsaturated fatty acids ( n-3 PUFA) can exert favourable effects in patients with heart failure, but the mechanisms involved are not fully understood. This study was designed to investigate the effects of n-3 PUFA on circulating inflammatory markers and N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with heart failure. Seventy-six patients with heart failure were randomly assigned to receive 2 g/day of n-3 PUFA or placebo for 3 months. Treatment with n-3 PUFA significantly decreased plasma levels of tumour necrosis factor, interleukin-6, intercellular adhesion molecule 1 and NT-proBNP. Left ventricular ejection fraction showed a small, non-significant improvement. High-sensitivity C-reactive protein levels decreased significantly in smokers after n-3 PUFA treatment. Thus, n-3 PUFA can reduce levels of plasma inflammatory markers and NT-proBNP as biomarkers of risk stratification in patients with heart failure. n-3 PUFA may offer a novel therapy for heart failure.

Relationship between quality of life and occupational stress among teachers

OBJECTIVES

With major changes in the education system and limited resources supplied by the Government, Chinese teachers have been suffering from greater occupational stress in recent years, which is believed to affect their physical and mental health. The aim of this study was to explore the relationship between quality of life and occupational stress in primary and middle school teachers.

STUDY DESIGN

Originals.

METHODS

A cross-sectional study was conducted using cluster sampling. The study population was composed of 3570 school teachers working in 64 primary and middle schools in Heping District in Shenyang, China. A demographic questionnaire, the 36-item Short-Form Health Survey (SF-36) and the Occupational Stress Inventory Revised Edition were employed to collect demographic variables and assess quality of life and occupational stress. Multivariate stepwise linear regression analyses were performed to study the relationship between quality of life and occupational stress.

RESULTS

The mean scores for both male and female teachers in this study were significantly lower than those for the Chinese general population for all dimensions of quality of life, except mental health and vitality (P<0.05). Male teachers scored significantly higher than female teachers for physical functioning, bodily pain, vitality and physical health (P<0.05). Age, role overload, role insufficiency, vocational strain, psychological strain, physical strain, recreation and rational coping were significantly associated with both the physical and mental component summaries of the SF-36 (P<0.05). Gender, physical environment and self-care appeared to be robust indicators of physical health (P<0.05), while role insufficiency, interpersonal strain and social support were strong indicators of mental health (P<0.05).

CONCLUSIONS

In China, teachers have a lower health status than the general population. The quality of life of female teachers is worse than that of male teachers, and deteriorates with age. Occupational stress and strain induce worsening physical and mental conditions for teachers, while coping resources could promote their health. This study suggests that having adequate coping resources, especially social support, in workplaces may be an important factor for improving teachers' quality of life. Moreover, psychological interventions should be set up for teachers, and psychological counselling should be provided to relieve stress and enhance quality of life.

Double-quantum NMR spectroscopy of 31P species submitted to very large CSAs

We introduce an original pulse sequence, BR2(2)(1)(taupitau), which is a block super-cycled R2(2)(1) sequence employing as basic element a pi pulse sandwiched by 'window' intervals. This homonuclear dipolar recoupling method allows the efficient excitation of double-quantum coherences between spin-1/2 nuclei submitted to very large chemical shift anisotropy. We demonstrate that this technique can be employed in double-quantum<-->single-quantum (31)P homonuclear correlation experiment at high magnetic field (B(0)>or=14 T) and high MAS frequencies (nu(R)>or=30 kHz). The performances of BR2(2)(1)(taupitau) are compared to those of the double-quantum recoupling methods, such as BABA and bracketed fp-RFDR, which were already employed at fast MAS rates. The BR2(2)(1)(taupitau) sequence displays a higher robustness to CSA and offset than the other existing techniques.

Double-quantum homonuclear NMR correlation spectroscopy of quadrupolar nuclei subjected to magic-angle spinning and high magnetic field

We present a new application of the R2(2)(1) symmetry-based dipolar recoupling scheme, for exciting directly double-quantum (2Q) coherences between the central transition of homonuclear half-integer quadrupolar nuclei. With respect to previously published 2Q-recoupling methods (M. Eden, D. Zhou, J. Yu, Chem. Phys. Lett. 431 (2006) 397), the R2(2)(1) sequence is used without pi/2 bracketing pulses and with an original super-cycling. This leads to an improved efficiency (a factor of two for spin-5/2) and to a much higher robustness to radio-frequency field inhomogeneity and resonance offset. The 2Q-coherence excitation performances are demonstrated experimentally by (27)Al NMR experiments on the aluminophosphates berlinite, VPI5, AlPO(4)-14, and AlPO(4)-CJ3. The two-dimensional 2Q-1Q correlation experiments incorporating these recoupling sequences allow the observation of 2Q cross-peaks between central transitions, even at high magnetic field where the difference in offset between octahedral and tetrahedral (27)Al sites exceeds 10 kHz.

The effects of fixed orthodontic appliances on saliva flow rate and saliva electrolyte concentrations

Fixed appliance orthodontic treatment may affect local saliva secretion; however, there is limited information available about this respect in the literature. Understanding how fixed appliance orthodontic treatment affects local saliva secretion could provide insight on possible contributions of salivary changes towards decalcification. In this study, we found that during the first month of fixed orthodontic treatment, the whole saliva flow rate, upper labial saliva flow rate and concentrations of whole saliva sodium and chlorine increased significantly, while the concentrations of calcium, phosphorous and potassium in whole saliva decreased. However, all these were in normal levels after 3 months. This study demonstrated that saliva flow rate was increased and saliva electrolytes were changed at early stage when placing fixed orthodontic appliances, which was considered due to increased mechanosensation.

Bifidobacterium longum as a delivery system of TRAIL and endostatin cooperates with chemotherapeutic drugs to inhibit hypoxic tumor growth

In our previous study, we have shown that vector pBV22210 containing a chloramphenicol resistance and a cryptic plasmid pMB1 from Bifidobacterium longum strain could stably replicate and did not significantly affect the biological characteristics of B. longum. In this study, B. longum was transfected by electroporation with pBV22210 encoding the extracellular domain of TRAIL (B. longum-pBV22210-TRAIL) and its carbohydrate fermentation and growth curve were determined, and its location and inhibitory effect on tumor xenografts in mice were also examined. The results further proved that gene transfection did not change the main biochemical characteristics of B. longum. The results also showed that B. longum-pBV22210-TRAIL resulted in selective location in tumors and exhibited a definite antitumor effect on S180 osteosarcoma. In addition, when a low dosage of Adriamycin (5 mg kg(-1)) or B. longum-pBV22210-endostatin was combined, the antitumor effect was significantly enhanced. The successful inhibition of S180 tumor growth suggested a stable vector in B. longum for transporting anticancer genes combined with low-dose chemotherapeutic drugs or other target genes is a promising approach in cancer gene therapy.

Recent advances in molecular targets and treatment of idiopathic pulmonary fibrosis: focus on TGFbeta signaling and the myofibroblast

Idiopathic Pulmonary Fibrosis (IPF) is characterized by injury and loss of lung epithelial cells, accumulation of fibroblasts/myofibroblasts and abnormal remodeling of the lung parenchyma. The prognosis for IPF patients is poor and current therapies are largely ineffective in preventing respiratory failure. Current therapeutic approaches target epithelial cell replacement, manipulation of fibroblasts/myofibroblasts, modulation of procoagulant/fibrinolytic activities, cytokine and growth factor production, angiogenesis, and reduction of oxidative stress. Myofibroblasts are the primary effector cells in fibrosis. These cells may be derived by the activation and proliferation of resident lung fibroblasts, from epithelial-mesenchymal transition (EMT), or through recruitment of circulating fibrocytes. Transforming growth factor beta (TGFbeta) is a profibrotic factor that increases fibroblast proliferation, stimulates the synthesis and deposition of connective tissue, and inhibits connective tissue breakdown. TGFbeta acts through the promoter of the type 1 collagen gene causing increased collagen synthesis. In addition, TGFbeta induces EMT in alveolar epithelial cells (AECs) in vitro and in vivo. AECs exhibit substantial plasticity and may serve as a source of fibroblasts and/or myofibroblasts in lung fibrosis. Therapeutic interventions interfering with the pathways that lead to myofibroblast expansion and AEC apoptosis should be of considerable benefit in the treatment of IPF. This review will focus on the critical role of TGFbeta on AECs EMT and myofibroblasts in the development of fibrosis.

Robust and efficient spin-locked symmetry-based double-quantum homonuclear dipolar recoupling for probing (1)H-(1)H proximity in the solid-state

We report a novel symmetry-based method, using inversion elements bracketed by spin locks, for exciting double-quantum (DQ) coherences between spin-1/2 nuclei, such as protons. Compared to previous DQ-recoupling techniques, this new pulse sequence requires moderate rf field, even at ultra-fast MAS speeds. Furthermore, it is easy to implement and it displays higher robustness to both chemical shift anisotropy and to spreads in resonance frequencies. These advances greatly facilitate the observation of (1)H-(1)H proximities at high fields and high MAS frequencies.

Correlation NMR spectroscopy involving quadrupolar nuclei

We review the recent developments proposed for integer or half-integer quadrupolar nuclei, focussing on the methods to observe them under high-resolution and to analyze their through-space and through-bond connectivities.

Persistent working memory dysfunction following traumatic brain injury: evidence for a time-dependent mechanism

The prefrontal cortex is highly vulnerable to traumatic brain injury (TBI) resulting in the dysfunction of many high-level cognitive and executive functions such as planning, information processing speed, language, memory, attention, and perception. All of these processes require some degree of working memory. Interestingly, in many cases, post-injury working memory deficits can arise in the absence of overt damage to the prefrontal cortex. Recently, excess GABA-mediated inhibition of prefrontal neuronal activity has been identified as a contributor to working memory dysfunction within the first month following cortical impact injury of rats. However, it has not been examined if these working memory deficits persist, and if so, whether they remain amenable to treatment by GABA antagonism. Our findings show that working memory dysfunction, assessed using both the delay match-to-place and delayed alternation T-maze tasks, following lateral cortical impact injury persists for at least 16 weeks post-injury. These deficits were found to be no longer the direct result of excess GABA-mediated inhibition of medial prefrontal cortex neuronal activity. Golgi staining of prelimbic pyramidal neurons revealed that TBI causes a significant shortening of layers V/VI basal dendrite arbors by 4 months post-injury, as well as an increase in the density of both basal and apical spines in these neurons. These changes were not observed in animals 14 days post-injury, a time point at which administration of GABA receptor antagonists improves working memory function. Taken together, the present findings, along with previously published reports, suggest that temporal considerations must be taken into account when designing mechanism-based therapies to improve working memory function in TBI patients.

Vascularization of engineered teeth

The implantation of cultured dental cell-cell re-associations allows for the reproduction of fully formed teeth, crown morphogenesis, epithelial histogenesis, mineralized dentin and enamel deposition, and root-periodontium development. Since vascularization is critical for organogenesis and tissue engineering, this work aimed to study: (a) blood vessel formation during tooth development, (b) the fate of blood vessels in cultured teeth and re-associations, and (c) vascularization after in vivo implantation. Ex vivo, blood vessels developed in the dental mesenchyme from the cap to bell stages and in the enamel organ, shortly before ameloblast differentiation. In cultured teeth and re-associations, blood-vessel-like structures remained in the peridental mesenchyme, but never developed into dental tissues. After implantation, both teeth and re-associations became revascularized, although later in the case of the re-associations. In implanted re-associations, newly formed blood vessels originated from the host, allowing for their survival, and affording conditions organ growth, mineralization, and enamel secretion.

Temporal and spatial expression of TGF-beta2 in tooth crown development in mouse first lower molar

Transforming Growth Factor beta2 (TGF-beta2) is involved in the regulation of many important cellular processes during tooth development. In this study we systematically characterized the expression pattern of TGF-beta2 in vivo and further analyzed its possible roles during different developmental stages of mouse first lower molar using immunofluorescence histochemical method with confocal microscopy. TGF-beta2 signaling was detected in different developing stages in both dental epithelium and surrounding dental mesenchyme. For the first time, we found that the basement membrane and epithelial cells in the basal layer showed no immunostaining from embryonic day 11 to 13; the primary enamel knot and secondary enamel knot exhibited pronounced immunostaining with different expression patterns at embryonic day 14 and 16. In addition, the mature ameloblast lost immunoreactivity, but the secretory ameloblast still exhibited positive immunoreaction at day 2 of postnatal development. Collectively, the temporospatial distribution patterns of TGF- beta2, especially in the basement membrane, epithelial cells in the basal layer, enamel knot, mature odontoblast and ameloblast, suggested a close association between TGF-beta2 signaling and tooth crown development, and indicated that TGF-beta2 might participate in tooth initiation, epithelial morphogenesis, formation of dentine matrix, and ameloblast differentiation.

EVALUATION OF A NOVEL EEG ANALYSIS METHOD WITH POTENTIAL DIAGNOSTIC APPLICATIONS

Background: Cerebral cortex oscillations as recorded on electroencephalograms involve multiple frequency bands. Phase locking of oscillations of these different frequencies may provide a mechanism by which regions of the brain communicate efficiently. Differences in the character of such phase locking may potentially be a diagnostic tool to differentiate seizure types, as traditional analysis of clinical EEG recordings has seldom considered phase-clocking as a diagnostic indicator. Recently, Canolty et al^1 used a novel metric to quantify cross-frequency phase-amplitude coupling during both spontaneous and induced EEG activity. The technique holds advantages over traditional measures, including easy comparison across trials, robustness to amplitude variation, and simple quantification of preferred phase. Traditional analysis of clinical EEG recordings has seldom considered phase-clocking as a diagnostic indicator. Methods: We adapted the metric of Canolty^1 to perform better with highly rhythmic oscillations, such as those in seizures, by adding multi-segment reshuffling of phase traces. To validate our modified technique, we used artificial sinusoid traces with a known degree of coupling to test the response of our modified analysis method, and to derive empirically, appropriate values for important numerical parameters. Frequency and phase information was acquired with both the Hilbert and wavelet transforms, with similar qualitative results achieved with either. Results: As an initial exploration of diagnostic potential, we applied our metric to field potential data obtained from an anaesthetized rat preparation. We compared the phase-amplitude coupling profiles of sleep oscillations with those of simulated absence seizures and showed consistent differences in the phase amplitude coupling profiles. The data suggest that such differences may be useful in evaluating human seizure data. Conclusions: We conclude that our modified method of data analysis provides an effective approach for measuring normalized phase-amplitude coupling in field potential recordings. Future work will aim to evaluate the possible diagnostic uses of phase-amplitude coupling analysis with data from human seizure patients. Reference: Canolty et al. Science 2006;313:1626. Supported by CIHR, NSERC, and the Health Research Foundation.

Analysis of the DPYD gene implicated in 5-fluorouracil catabolism in Chinese cancer patients

BACKGROUND AND OBJECTIVE

5-fluorouracil (5-FU) is still a widely used anticancer drug. More than 85% of the 5-FU administered is catabolized by dihydropyrimidine dehydrogenase (DPD) in the liver. However, mutations in the DPD gene have been found to be associated with low DPD activity causing severe complications. The purpose of this study was to determine the mutation frequency of four exons in Chinese cancer patients and the relationship between genotype and DPD activity.

METHODS

Samples from 142 cancer patients were investigated in this study. The DPD activity was determined by reversed-phase HPLC. Exons 2, 13, 14 and 18 were amplified by polymerase chain reaction (PCR), sequenced and analysed from both sense and antisense directions. Nonparametric one-sample Kolmogorov-Smirnov test was used for distribution analysis; two independent samples t-test and one-way anova was performed for two groups and three groups analyses, respectively.

RESULTS AND DISCUSSION

Plasma-DPD activities in the 142 cancer patients followed a Gaussian distribution. The mean plasma-DPD activity in women was lower than that in men (P = 0.006). Four mutations, 85T>C(DPYD*9A), 1627A>G(DPYD*5), 1896T>C and 2194G>A(DPYD*6), were found in the 142 cancer patients. The following mutations reported by others were not detected: 61C>T, 62G>A, 74A>G, 1601G>A(DPYD*4), 1679T>G(DPYD*13), 1714C>G, 1897delC(DPYD*3) and IVS 14 + 1G>A. No significant correlation was found between three mutations [85T>C(DPYD*9A), 1627A>G (DPYD*5) and 1896T>C], and DPD activity was found.

CONCLUSION

No clear correlation between the mutations studied and DPD activity could be established in this study. However, larger-scale prospective studies are needed to better assess the reported genotype-phenotype correlations.