Restorative effect of NitroSynapsin on synaptic plasticity in an animal model of depression

In the search for new options for the pharmacological treatment of major depressive disorder, compounds with a rapid onset of action and high efficacy but lacking a psychotomimetic effect are of particular interest. In the present study, we evaluated the antidepressant potential of NitroSynapsin (NS) at behavioural, structural, and functional levels. NS is a memantine derivative and a dual allosteric N-methyl-d-aspartate receptors (NMDAR) antagonist using targeted delivery by the aminoadamantane of a warhead nitro group to inhibitory redox sites on the NMDAR. In a chronic restraint stress (CRS) mouse model of depression, five doses of NS administered on three consecutive days evoked antidepressant-like activity in the chronically stressed male C57BL/6J mice, reversing CRS-induced behavioural disturbances in sucrose preference and tail suspension tests. CRS-induced changes in morphology and density of dendritic spines in cerebrocortical neurons in the medial prefrontal cortex (mPFC) were also reversed by NS. Moreover, CRS-induced reduction in long-term potentiation (LTP) in the mPFC was found to be prevented by NS based on the electrophysiological recordings. Our study showed that NS restores structural and functional synaptic plasticity and reduces depressive behaviour to the level found in naïve animals. These results preliminarily revealed an antidepressant-like potency of NS.

Oleanolic acid enhances neural stem cell migration, proliferation, and differentiation in vitro by inhibiting GSK3β activity

Oleanolic acid (OA), one of the bioactive ingredients in ginseng, has been reported to have neuroprotective activities. However, the effects and its mechanism on neural stem cell (NSC) induction are not entirely clear. In the present study, we investigated the effects of OA on promoting the migration, proliferation, and differentiation of neural stem cells (NSCs). Migration and proliferation were investigated by using neural-specific markers, neurosphere assay, and Cell Counting Kit-8, respectively. We found OA remarkably promoted neural migration and proliferation of NSCs in a time- and dose-dependent manner. Differentiation was analyzed by western blotting and immunofluorescence staining, which found MAP2 expression was remarkably increased, whereas Nestin was dramatically decreased. In addition, OA increased phosphorylation of GSK3β at Ser9 and expression of active forms of β-catenin. Furthermore, NSCs with constitutively active GSK3β (S9A) significantly suppressed the OA-induced proliferation and neural differentiation. These results showed that OA could stimulate NSC proliferation and neural differentiation in vitro via suppressing the activity of GSK3β. Our findings may have significant implications for the treatment of neurodegenerative diseases.

Community-associated methicillin-resistant Staphylococcus aureus skin and soft tissue infections in Hong Kong

Community-associated methicillin resistant Staphylococcus aureus is an emerging cause of skin and soft tissue infections in Hong Kong, especially among certain ethnic minorities.

Molecular epidemiology of community-associated methicillin-resistant Staphylococcus aureus

1. Community-associated methicillin-resistant Staphylococcus aureus (MRSA) strains with diverse genetic backgrounds are emerging in Hong Kong. 2. Intra-familial spread of community-associated MRSA is common.

Molecular characterization of clinical isolates of Mycobacterium tuberculosis and their association with phenotypic virulence in human macrophages

Among 125 clinical isolates of Mycobacterium tuberculosis collected in Hong Kong and Shanghai, China, between 2002 and 2004, IS6110 typing revealed that 71 strains (57%) belonged to the Beijing family. The intracellular growth of the strains in human peripheral blood monocyte-derived macrophages was measured ex vivo on days 0, 3, 6, and 10. Among all tested strains, three hypervirulent strains showed significant increases in intracellular growth after 10 days of incubation. With an initial bacterial load of 10(4) CFU, most of the clinical isolates and H37Ra (an avirulent strain) exhibited no intracellular survival on day 10, while the three hypervirulent strains together with H37Rv (a virulent strain) showed on average a two- to fourfold rise in CFU count. These three hypervirulent strains belonging to a non-Beijing family were isolated from patients suffering from tuberculosis meningitis. Cytokines secreted by gamma interferon-activated macrophages were measured daily after challenge with selected strains of M. tuberculosis. The levels of tumor necrosis factor alpha were elevated after 24 h of infection among all strains, but the levels were significantly lower among the three hypervirulent strains, whereas interleukin 10 (IL-10) and IL-12 were not detected. Results were concordant with the differential expression of the corresponding cytokine genes in activated macrophages, as monitored by real-time PCR. Our findings highlighted that these three hypervirulent strains may possess an innate mechanism for escaping host immunity, which accounts for their characteristic virulence in patients presenting with a more severe form of disease.

Noradrenaline Might Enhance Assertive Human Social Behaviours: An Investigation in a Flatmate Relationship

OBJECTIVE

The aim of the present study was to explore the role of noradrenaline on the social behaviour of healthy volunteers when they were interacting with a familiar person, their flatmate. Interaction with the flatmate was explored in a cooperative game situation.

METHODS

Ten pairs of same-sex healthy volunteer flatmates aged 18-25 years were recruited for the experiment. All volunteers gave written informed consent and the study was approved by the institutional ethical committee. A randomised, double blind, placebo-controlled crossover trial of reboxetine versus placebo was conducted. In each of the 10 pairs of volunteers, one (subject) volunteered to take the tablets and the other (flatmate) received no treatment. Reboxetine (4 mg/bd) and placebo were administered orally as identical capsules for 2 weeks. The subjects were randomly assigned to receive either reboxetine or placebo first and there was a two-week washout period following the first treatment. At baseline and the end of each treatment, they filled in the Beck Depression Inventory (BDI), Social Adapation Self-Evaluation Scale (SASS), and Aggression Questionnaire (AQ). Then, they were instructed to play the Tangrams game. This task elicits face-valid social behaviours such as cooperation, giving commands and unilateral grasps.

RESULTS

Analysis of covariance showed that there was a statistical trend for reboxetine treatment to increase commands (p=0.055).

CONCLUSION

This study presents preliminary evidence that two weeks' enhancement of noradrenaline transmission induced by reboxetine makes healthy volunteers more self-confident and assertive.

Development and validation of the Two-Dimensional Social Interaction Scale (2DSIS)

The Two-Dimensional Social Interaction Scale (2DSIS) is a newly developed 20-item observer rating scale to assess four distinct categories of social interaction: active participate; active non-participate; passive participate; and passive non-participate. The scale was submitted to a validation procedure based on video recording of 59 dyadic social interactions between a confederate enacting one of the four types of social behaviours and a participant. The 2DSIS observer ratings on the participants were associated with meaningful differences in participants' social behaviour and their scores on the Social Adaptation Self-evaluation Scale. The 2DSIS observer ratings on the confederates were associated with participants' Post Encounter Scale scores. Factor analysis suggested that the four category ratings did exist in the two dimensions as proposed. The 2DSIS could be used in conjunction with conventional assessment tools to evaluate the social functioning of individuals.

Serotonergic involvement in the psychosocial dimension of personality

Neurotransmitter systems have been associated with aspects of personality and changes in various dimensions have been shown after antidepressant treatment. A reduction in harm avoidance and an increase in self-directedness and cooperativeness, as measured by the Cloninger's Temperament and Character Inventory (TCI), have been reported in psychiatric patients receiving treatment with serotonergic antidepressants. However, some of these changes have been associated with clinical improvement. The present study therefore used a randomized, double-blind, placebo-controlled design to examine the role of the serotonergic system on these personality factors in the normal population. Twenty healthy male volunteers were randomly allocated to either placebo (n = 9) or citalopram treatment (n = 11) for 2 weeks. Baseline depression and anxiety scores were low and did not differ between groups. The TCI was administered pre- and post-treatment. There were no baseline differences on any TCI factor between groups. Citalopram induced a significant increase in self-directedness (p < 0.05) but not cooperativeness or harm avoidance ratings after treatment. Thus, citalopram has effects on personality aspects which appear to be separate from its antidepressant properties.

Risk factors for acquisition of levofloxacin-resistant Streptococcus pneumoniae: a case-control study

A case-control study was conducted to identify the risk factors associated with levofloxacin-resistant Streptococcus pneumoniae (LRSP) colonization or infection. Twenty-seven case patients (patients with LRSP) were compared with 54 controls (patients with levofloxacin-susceptible S. pneumoniae). Risk factors that were significantly associated with LRSP colonization or infection, according to univariate analysis, included an older age (median age, 75 years for case patients versus 72.5 years for controls), residence in a nursing home (odds ratio [OR], 7.2), history of recent (OR, 4.6) and multiple (OR, 4.4) hospitalizations, prior exposure to fluoroquinolones (OR, 10.6) and beta-lactams (OR, 8.6), presence of chronic obstructive pulmonary disease (COPD; OR, 5.9), and nosocomial origin of the bacteria (OR, 5.7). Multivariate analysis showed that presence of COPD (OR, 10.3), nosocomial origin of the bacteria (OR, 16.2), residence in a nursing home (OR, 7.4), and exposure to fluoroquinolones (OR, 10.7) were independently associated with LRSP colonization or infection. Thus, a distinct group of patients with COPD is the reservoir of LRSP.

Clinical experience with Sensolog 703: a new activity sensing rate responsive pacemaker

Sensolog 703 is a new activity sensing rate responsive pacemaker which detects body vibration during physical exercise and uses the vibration as an indicator of the physiological need for a rate increase. This pacemaker was implanted in 11 patients with complete heart block and atrial arrhythmias. Their mean age was 58 (range 39-72) years. With appropriate rate response, exercise capacity, as assessed by the duration of graded treadmill exercise using the Bruce protocol, was significantly improved over the VVI pacing mode (mean +/- SEM, 462 +/- 52 s in the rate responsive mode and 368 +/- 34 s in the VVI mode, P less than 0.02). Cardiac output at peak exercise, as assessed by continuous wave Doppler sampling of aortic root blood flow, was also significantly increased compared to the resting value in both piecing modes. However, the increase was more marked when exercise was performed in the rate response mode (93 +/- 22% increase over resting cardiac output in the rate responsive mode and 57 +/- 13% increase in the VVI mode, P less than 0.05). The rate responses of this pacemaker were compared with those of a Medtronic Activitrax pacemaker. Although both pacemakers responded to an increase in walking speed, neither responded appropriately to walking up different gradients, In both cases, ascending and descending four flights of stairs resulted in similar pacing rates. There was no response to physiological activities with minimal body movements such as isometric exercise and the Valsalva maneuver. Technical problems were encountered in two implanted Sensolog pacemakers: one had spontaneous rate acceleration at rest immediately following implantation and one showed intermittent rate acceleration while the patient was at rest. Both units were programmed to the VVI mode. In conclusion, satisfactory rate response, improvement in exercise duration and increase in cardiac output were achieved with the Sensolog 703 pacemaker. However, as body vibration is not closely related to physiological needs, it has similar limitations in rate response as the Activitrax pacemaker.