Laser-induced thermal stress and the heat shock response in neural cells

Background?The Ho: YAG laser is used extensively in orthopedic surgery. It offers a minimally invasive method of ablating tissue with precision. Previous studies have explored the effects of laser use on temperature during experimental foraminoplasty. To date, there has been limited work on the effects of thermal stress on cells in this context.Material and methods?Cells were exposed either to heated medium or the Ho: YAG laser in the high-power mode. Heated medium was used as a stressor by (I) exposing groups of cells to a constant temperature of 45°C for varying lengths of time: 5, 10, 15 and 20 min, and (II) exposing cells for a fixed length of time (5 min) to varying temperatures: 45°C, 55°C, 65°C with a control treated at 37°C. A third group was subjected to direct laser treatment. The effects of the treatments were assessed using trypan blue staining as a measure of viability and immunocytochemistry was used to measure changes in heat shock protein (HSP) expression.Results?There was a negative correlation between cell viability and HSP expression, and between cell viability and the severity of the treatment.Interpretation?Our findings suggest a possible role for the Ho: YAG laser in spinal foraminoplasty based on the high level of cell viability in the treatment regimen that most closely mirrored the clinical application of the laser.     

Hemispheric alpha asymmetries of aphasic and normal subjects: Results from recognition and recall tasks using visually presented words of high and low imagery

Abstract

Hemispheric alpha asymmetries of normal males, normal females, and male aphasics were observed from anterior and posterior placement sites for recall and recognition of visually presented high and low imagery words, and during resting conditions. No significant differences were observed during the resting conditions between groups. However, during visual presentation of words the aphasics demonstrated significantly less alpha in the right hemisphere, while no differences were observed for the normal subjects. Both fluent and non-fluent aphasics demonstrated right hemisphere alpha suppression across stimulus and task conditions. The non-fluent aphasics demonstrated lower overall alpha power levels across hemispheres than did the fluent aphasics. Results are discussed relative to the aphasics becoming more dependent upon the processing resources of the intact right hemisphere during the course of language recovery.     

Examining attention and cognitive processing in participants with self-reported mild anomia

Background: People who report mild anomia following stroke often score near or within normal limits on traditional assessments of language. Based on evidence of cognitive influences on linguistic production in people with aphasia, this study examined non-linguistic, cognitive function and its potential influence on word retrieval in individuals with mild anomia.

Aims: This study explored the following research questions: Do people with mild anomia have impaired performance on tasks which require (a) automatic vs controlled processing and/or (b) selective attention relative to neurologically typical controls?

Methods & Procedures: A total of 14 participants with mild anomia and 9 neurologically typical controls were tested using Covert Orienting of Visuospatial Attention Test (COVAT), alone and with linguistic interference, at two interstimulus intervals (ISI) representing automatic and controlled processing.

Outcomes & Results: Participants with anomia showed significantly slower responses on COVAT alone at 100 ms ISI (automatic processing) compared with controls. The groups did not differ significantly during COVAT alone at 800 ms ISI (controlled processing). Additionally, similar priming patterns were exhibited by both groups on COVAT alone during both interstimulus intervals, indicating an intact validity effect. However, participants with anomia demonstrated significantly delayed response times during the COVAT with linguistic interference, regardless of ISI.

Conclusions: Overall, participants with mild anomia demonstrated impairments most notably when interfering stimuli were present, indicating deficits in automatic processing and selective attention. Study results support clinical evaluation of non-linguistic cognitive abilities in individuals reporting anomia who score near or within normal limits on language assessments.     

The effect of stuttering on communication: A preliminary investigation

This paper describes a study in which Systemic Functional Linguistics was applied to describe how people who stutter use language. The aim of the study was to determine and describe any differences in language use between a group of 10 adults who stutter and 10 matched normally‐fluent speakers. In addition to formal linguistic analyses, analyses drawn from Systemic Functional Linguistics were used to further investigate the expression of both syntactic and semantic complexity. The findings from this study replicated previous findings of Packman et al. in which they found that the language used by people who stutter was significantly less complex than the control group. Another major finding was that adults who stuttered used the linguistic resource of modality significantly less than the normally‐fluent matched peers. The implications these strategies have on communication and social participation will be discussed.     

Canonical transient receptor potential channel subtype 3‐mediated hair cell Ca2+ entry regulates sound transduction and auditory neurotransmission

The physiological significance of canonical transient receptor potential (TRPC) ion channels in sensory systems is rapidly emerging. Heterologous expression studies show that TRPC3 is a significant Ca²⁺ entry pathway, with dual activation via G protein‐coupled receptor (GPCR)–phospholipase C–diacylglycerol second messenger signaling, and through negative feedback, whereby a fall in cytosolic Ca²⁺ releases Ca²⁺–calmodulin channel block. We hypothesised that the latter process contributes to cochlear hair cell cytosolic Ca²⁺ homeostasis. Confocal microfluorimetry with the Ca²⁺ indicator Fluo‐4 acetoxymethylester showed that, when cytosolic Ca²⁺ was depleted, Ca²⁺ re‐entry was significantly impaired in mature TRPC3^?/? inner and outer hair cells. The impact of this disrupted Ca²⁺ homeostasis on sound transduction was assessed with the use of distortion product otoacoustic emissions (DPOAEs), which constitute a direct measure of the outer hair cell transduction that underlies hearing sensitivity and frequency selectivity. TRPC3^?/? mice showed significantly stronger DPOAE (2f₁ ? f₂) growth functions than wild‐type (WT) littermates within the frequency range of best hearing acuity. This translated to hyperacusis (decreased threshold) measured by the auditory brainstem response (ABR). TRPC3^?/? and WT mice did not differ in the levels of temporary and permanent threshold shift arising from noise exposure, indicating that potential GPCR signaling via TRPC3 is not pronounced. Overall, these data suggest that the Ca²⁺ set‐point in the hair cell, and hence membrane conductance, is modulated by TRPC3s through their function as a negative feedback‐regulated Ca²⁺ entry pathway. This TPRC3‐regulated Ca²⁺ homeostasis shapes the sound transduction input–output function and auditory neurotransmission.     

Mental disorders: employment and work productivity in Singapore

Aim

To examine the association between mental disorders and work disability in the adult resident population in Singapore.

Method

Data are from the Singapore Mental Health Study, which was a household survey of a nationally representative sample. The main instrument used was the Composite International Diagnostic Interview (CIDI). Employment-related information was collected using the modified employment module of the CIDI.

Results

A total of 6,429 respondents were included in the analysis, 71 % (n = 4,594) were employed, 24.5 % (n = 1,522) were economically inactive and 4.5 % (n = 313) were unemployed. Among the employed, 2.3 % had a 12-month prevalence of at least one mental disorder, while 5.3 % of the unemployed had at least one mental disorder. The average number of work loss days (absenteeism) per capita among those with a mental disorder was 0.5 per month that is equivalent to an annualized national projection of approximately 0.3 million productivity days. The average work-cutback days (presenteeism) were 0.4 days among this group. Of the mentally ill in the workforce, a high proportion (86.5 %) did not ever seek help for problems related to mental health.

Conclusion

Our findings provide information on the significant consequences of mental disorders on the workforce in terms of lost work productivity, which could pave the way for a more rational allocation of scarce resources.