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Schizotypy refers to schizophrenia-like traits below the clinical threshold in the general population. The pathological development of schizophrenia has been postulated to evolve from the initial coexistence of ‘brain disconnection’ and ‘brain connectivity compensation’ to ‘brain connectivity decompensation’.
In this study, we examined the brain connectivity changes associated with schizotypy by combining brain white matter structural connectivity, static and dynamic functional connectivity analysis of diffusion tensor imaging data and resting-state functional magnetic resonance imaging data. A total of 87 participants with a high level of schizotypal traits and 122 control participants completed the experiment. Group differences in whole-brain white matter structural connectivity probability, static mean functional connectivity strength, dynamic functional connectivity variability and stability among 264 brain sub-regions of interests were investigated.
We found that individuals with high schizotypy exhibited increased structural connectivity probability within the task control network and within the default mode network; increased variability and decreased stability of functional connectivity within the default mode network and between the auditory network and the subcortical network; and decreased static mean functional connectivity strength mainly associated with the sensorimotor network, the default mode network and the task control network.
These findings highlight the specific changes in brain connectivity associated with schizotypy and indicate that both decompensatory and compensatory changes in structural connectivity within the default mode network and the task control network in the context of whole-brain functional disconnection may be an important neurobiological correlate in individuals with high schizotypy.
Little is known about long-term employment outcomes for patients with first-episode schizophrenia-spectrum (FES) disorders who received early intervention services.
We compared the 10-year employment trajectory of patients with FES who received early intervention services with those who received standard care. Factors differentiating the employment trajectories were explored.
Patients with FES (N = 145) who received early intervention services in Hong Kong between 1 July 2001 and 30 June 2002 were matched with those who entered standard care 1 year previously. We used hierarchical clustering analysis to explore the 10-year employment clusters for both groups. We used the mixed model test to compare cluster memberships and piecewise regression analysis to compare the employment trajectories of the two groups.
There were significantly more patients who received the early intervention service in the good employment cluster (early intervention: N = 98 [67.6%]; standard care: N = 76 [52.4%]; P = 0.009). In the poor employment cluster, there was a significant difference in the longitudinal pattern between early intervention and standard care for years 1–5 (P < 0.0001). The number of relapses during the first 3 years, months of full-time employment during the first year and years of education were significant in differentiating the clusters of the early intervention group.
Results suggest there was an overall long-term benefit of early intervention services on employment. However, the benefit was not sustained for all patients. Personalisation of the duration of the early intervention service with a focus on relapse prevention and early vocational reintegration should be considered for service enhancement.
Although electromyography (EMG), electroencephalography (EEG) and evoked potential (EP) studies are common investigation tools for patients with neurologic illnesses, no formal data on the manpower supply in Canada exists. Because of the importance of these on training requirements and future planning, the purpose of this study was to establish a comprehensive profile of the human resources situation in clinical neurophysiological services across Canada.
A questionnaire was sent to all clinical neurophysiologists in Canada. To capture the maximal number of respondents, a total of three rounds of mail out were done. In addition, to obtain accurate demographic data on supporting technologists, a separate survey was also carried out by the Association of Electrophysiological Technologists of Canada.
Of the 450 clinical neurophysiologists identified and surveyed, the provincial response rate was 59±14% (mean±SD). Of these, the vast majority practiced in urban centres. There was substantial regional disparity in different provinces. While the wait time for most EEG and EP laboratories was less than six weeks, the wait time for EMG was substantially longer. With the age of the largest number of practitioners in their sixth decade, projected retirement over the next 15 years was 58%. The demographic distribution of the supporting technologists showed a similar trend.
In addition to considerable regional disparity and urban/rural divide, a large percentage of clinical neurophysiologists and supporting technologists planned to retire within the coming decade. To ensure secure and high standard services to Canadians, solutions to fill this void are urgently needed.
Motor unit number estimation (MUNE) is an electrophysiological method designed to quantify motor unit loss in target muscles of interest. Most of the techniques are noninvasive and are therefore well suited for longitudinal monitoring. In this brief review, we describe the more commonly used techniques and their applications in amyotrophic lateral sclerosis, poliomyelitis, spinal muscular atrophy and hereditary sensorimotor neuropathies. Findings in some of these studies offer important pathophysiological insights. Since conventional electrophysiologic methods are not sensible measures of motor neuronal loss, MUNE could play a potentially important role in the diagnosis, monitoring of disease progression and response to treatment in neuromuscular diseases in which motor unit loss is a major feature.
Dental remineralization may be achieved by mediating the interactions between tooth surfaces with free ions and biomimetic peptides. We recently developed octuplet repeats of aspartate-serine-serine (DSS-8) peptide, which occurs in high abundance in naturally occurring proteins that are critical for tooth remineralization. In this paper, we evaluated the possible role of DSS-8 in enamel remineralization. Human enamel specimens were demineralized, exposed briefly to DSS-8 solution, and then exposed to concentrated ionic solutions that favor remineralization. Enamel nano-mechanical behaviors, hardness and elastic modulus, at various stages of treatment were determined by nanoindentation. The phase, microstructure and morphology of the resultant surfaces were characterized using the grazing incidence X-ray diffraction (GIXD), variable pressure scanning electron microscopy (VPSEM), and atomic force microscopy (AFM), respectively. Nanoindentation results show that the DSS-8 remineralization effectively improves the mechanical and elastic properties for demineralized enamel.
Epidemiological studies have indicated that soya consumption may produce a better plasma lipid profile. The effect may be attributed to the phyto-oestrogens in soya. The red clover (Trifolium pratense) isoflavone biochanin A has a chemical structure similar to those phyto-oestrogens found in soya beans, and is marketed as a nutraceutical for alleviating postmenopausal symptoms. In the present study we investigated the effect of biochanin A on the mRNA expression of ApoA-1 in the hepatic cell line HepG2. Real-time PCR revealed that biochanin A increased ApoA-1 mRNA abundance in cells expressing oestrogen receptor (ER) α. Without ERα transfection, biochanin A had no effect on mRNA abundance. In order to study the transcriptional control, a fragment of the 5′-flanking region of the ApoA-1 gene was amplified and inserted in a firefly luciferase reporter plasmid. The reporter assay indicated that the transactivation of the ApoA-1 promoter was induced by biochanin A in HepG2 cells transfected with the ERα expression plasmid. This induction was reduced by the anti-oestrogen ICI 182,780, whereas the inhibitors of protein kinase (PK) C, PKA, or mitogen-activated kinase (ERK) had no suppressive effect. The present study illustrated that biochanin A might up regulate hepatic apoA-1 mRNA expression through an ER-dependent pathway.
Insulin-like growth factors (IGF) belong to a family of growth factors with structural homology to proinsulin. In our previous studies, we found that both IGF-I and IGF-II gene expression showed growth hormone (GH) dependence in the brain and liver of juvenile common carp when treated in vivo with GH for a short time. This present work aimed to study the effects of both the short-term and long-term GH induction of IGF gene expression using cysteamine (CSH) and fasting/re-feeding. CSH is an agent that can deplete somatostatin to increase circulating GH level. IGF mRNA levels in the flesh (muscle) and liver of common carp were determined using real-time PCR.
The chronic treatment of common carp with CSH was carried out for 63d, with growth enhancement of the treated fish noted. Hepatic IGF-I and IGF-II mRNA levels increased in a dose-dependent manner with short-term CSH treatment, whereas IGF-I decreased and IGF-II increased in the liver after chronic CSH treatment. IGF-I and IGF-II mRNA levels in muscle were found to be elevated with the high-dose, long-term CSH treatment. Under the experimentally induced catabolic states of fasting, both hepatic IGF-I and IGF-II gene expression were significantly reduced, whereas they showed no change in muscle. After re-feeding, the hepatic expression of IGF-I in liver and muscle rebounded significantly. The hepatic IGF-II expression level showed no rebound after re-feeding, but the IGF-II level in muscle rebounded to the level of the fed group after re-feeding.
Cladding failure of fuel rods caused by hydride-induced embrittlement is a reliability concern for spent nuclear fuel after extended burnup. Uncertainties in the cladding temperature, cladding stress, oxide layer thickness, and the critical stress value for hydride reorientation preclude an assessment of the cladding failure risk. A set of micromechanical models for treating oxide cracking, blister cracking, delayed hydride cracking, and cladding fracture was developed and incorporated in a computer model. Results obtained from the model calculations indicate that at temperatures below a critical temperature of 318.5 °C [605.3 °F], the time to failure by delayed hydride cracking in Zr-2.5%Nb decreased with increasing cladding temperature. The overall goal of this project is to develop a probabilistic-micromechanical methodology for assessing the probability of hydride-induced failure in Zircaloy cladding and thereby establish performance criteria.
The goal of this study was to compare the relative contributions from the muscle and the central nervous system to muscle fatigue resistance in aging.
Each subject carried out 90 s of sustained maximal voluntary isometric contraction (MVC) of the thumb using the thenar and forearm thumb muscles. Contractile capacity of the thenar muscles was assessed through tetanic stimulation of the median nerve. Interpolated doublets delivered during an MVC represented the overall voluntary activation level while transcranial cortical stimulation with an electromagnetic stimulator was used to assess motor output upstream from the corticomotoneuronal pathway.
Nine elderly subjects [four females and five males, 70±9 years old (mean±SD)] and 10 younger subjects (five females and five males, 30±6 years old) were tested. After the fatiguing exercise, the elderly group's MVC declined by 29% as opposed to 47% in the younger group (p<0.01). The elderly group's greater fatigue resistance was accounted for by increased fatigue resistance at the muscle level as well as in the central nervous system. At least some of the decline in the central motor drive was upstream from the corticomotoneuronal pathway.
The higher muscle fatigue resistance in the elderly group was attributable to differences in both the peripheral and central nervous systems.
The neuromuscular system may be affected by disorders of the central nervous system as well as other disorders affecting motoneurons, axons, neuromuscular transmission, the sarcolemmal membrane, the contractile elements and other components of the muscle fibers themselves. One or a combination of these possibilities can present in patients in the critical care unit. This paper reviews various qualitative and quantitative methods for assessing the various components of the peripheral contributions to the electrical and force output as well as the central motor drive to motoneurons. These methods all have their own strengths and weaknesses but many are complementary and together, can provide important diagnostic and prognostic information to guide management.
As the one and a half centuries of British colonial rule draw to a close on 30 June 1997, it is timely to review the true legacy of British administration in Hong Kong. It would be naive to resort to any simplistic blanket judgment or to issue any sweeping endorsement or condemnation on the mixed record of the British administration. It would also be dangerous to look only at the attainments in the final days of the British regime and use them to reconstruct, or even to substitute for, the full span of British rule. Even given a charitable view of this sunset era of the British regime as its finest hour in Hong Kong, a more informed and balanced assessment of its past deeds must be appreciated in the fuller context of the actual inputs and outputs of British officialdom in shaping developments in the territory and the life of Hong Kong people during the entire course of British rule.