Harnessing the potential of data-driven strategies to optimise transfusion practice

No one doubts the significant variation in the practice of transfusion medicine. Common examples are the variability in transfusion thresholds and the use of tranexamic acid for surgery with likely high blood loss despite evidence-based standards. There is a long history of applying different strategies to address this variation, including education, clinical guidelines, audit and feedback, but the effectiveness and cost-effectiveness of these initiatives remains unclear. Advances in computerised decision support systems and the application of novel electronic capabilities offer alternative approaches to improving transfusion practice. In England, the National Institute for Health and Care Research funded a Blood and Transplant Research Unit (BTRU) programme focussing on 'A data-enabled programme of research to improve transfusion practices'. The overarching aim of the BTRU is to accelerate the development of data-driven methods to optimise the use of blood and transfusion alternatives, and to integrate them within routine practice to improve patient outcomes. One particular area of focus is implementation science to address variation in practice.

Toxicity assessment of CeO₂ and CuO nanoparticles at the air-liquid interface using bioinspired condensational particle growth

CeO2 and CuO nanoparticles (NPs) are used as additives in petrodiesel to enhance engine performance leading to reduced diesel combustion emissions. Despite their benefits, the additive application poses human health concerns by releasing inhalable NPs into the ambient air. In this study, a bioinspired lung cell exposure system, Dosimetric Aerosol in Vitro Inhalation Device (DAVID), was employed for evaluating the toxicity of aerosolized CeO2 and CuO NPs with a short duration of exposure (≤10 min vs. hours in other systems) and without exerting toxicity from non-NP factors. Human epithelial A549 lung cells were cultured and maintained within DAVID at the air-liquid interface (ALI), onto which aerosolized NPs were deposited, and experiments in submerged cells were used for comparison. Exposure of the cells to the CeO2 NPs did not result in detectable IL-8 release, nor did it produce a significant reduction in cell viability based on lactate dehydrogenase (LDH) assay, with a marginal decrease (10%) at the dose of 388 μg/cm2 (273 cm2/cm2). In contrast, exposure to CuO NPs resulted in a concentration dependent reduction in LDH release based on LDH leakage, with 38% reduction in viability at the highest dose of 52 μg/cm2 (28.3 cm2/cm2). Cells exposed to CuO NPs resulted in a dose dependent cellular membrane toxicity and expressed IL-8 secretion at a global dose five times lower than cells exposed under submerged conditions. However, when comparing the ALI results at the local cellular dose of CuO NPs to the submerged results, the IL-8 secretion was similar. In this study, we demonstrated DAVID as a new exposure tool that helps evaluate aerosol toxicity in simulated lung environment. Our results also highlight the necessity in choosing the right assay endpoints for the given exposure scenario, e.g., LDH for ALI and Deep Blue for submerged conditions for cell viability.

Retrospective Analysis of Wastewater-Based Epidemiology of SARS-CoV-2 in Residences on a Large College Campus: Relationships between Wastewater Outcomes and COVID-19 Cases across Two Semesters with Different COVID-19 Mitigation Policies

Wastewater-based epidemiology (WBE) has been utilized for outbreak monitoring and response efforts in university settings during the coronavirus disease 2019 (COVID-19) pandemic. However, few studies examined the impact of university policies on the effectiveness of WBE to identify cases and mitigate transmission. The objective of this study was to retrospectively assess relationships between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wastewater outcomes and COVID-19 cases in residential buildings of a large university campus across two academic semesters (August 2020-May 2021) under different COVID-19 mitigation policies. Clinical case surveillance data of student residents were obtained from the university COVID-19 response program. We collected and processed building-level wastewater for detection and quantification of SARS-CoV-2 RNA by RT-qPCR. The odds of obtaining a positive wastewater sample increased with COVID-19 clinical cases in the fall semester (OR = 1.50, P value = 0.02), with higher odds in the spring semester (OR = 2.63, P value < 0.0001). We observed linear associations between SARS-CoV-2 wastewater concentrations and COVID-19 clinical cases (parameter estimate = 1.2, P value = 0.006). Our study demonstrated the effectiveness of WBE in the university setting, though it may be limited under different COVID-19 mitigation policies. As a complementary surveillance tool, WBE should be accompanied by robust administrative and clinical testing efforts for the COVID-19 pandemic response.

LGMDD1 natural history and phenotypic spectrum: Implications for clinical trials

OBJECTIVE

To delineate the full phenotypic spectrum and characterize the natural history of limb girdle muscular dystrophy type D1 (LGMDD1).

METHODS

We extracted age at clinical events of interest contributing to LGMDD1 disease burden via a systematic literature and chart review. Manual muscle testing and quantitative dynamometry data were used to estimate annualized rates of change. We also conducted a cross-sectional observational study using previously validated patient-reported outcome assessments (ACTIVLIM, PROMIS-57) and a new LGMDD1 questionnaire. Some individuals underwent repeat ACTIVLIM and LGMDD1 questionnaire assessments at 1.5 and 2.5 years.

RESULTS

A total of 122 LGMDD1 patients were included from 14 different countries. We identified two new variants (p.E54K, p.V99A). In vitro assays and segregation support their pathogenicity. The mean onset age was 29.7 years. Genotype appears to impact onset age, weakness pattern, and median time to loss of ambulation (34 years). Dysphagia was the most frequent abnormality (51.4%). Deltoids, biceps, grip, iliopsoas, and hamstrings strength decreased by (0.5-1 lb/year). Cross-sectional ACTIVLIM and LGMDD1 questionnaire scores correlated with years from disease onset. Longitudinally, only the LGMDD1 questionnaire detected significant progression at both 1.5 and 2.5 years. Treatment trials would require 62 (1.5 years) or 30 (2.5 years) patients to detect a 70% reduction in the progression of the LGMDD1 questionnaire.

INTERPRETATION

This study is the largest description of LGMDD1 patients to date and highlights potential genotype-dependent differences that need to be verified prospectively. Future clinical trials will need to account for variability in these key phenotypic features when selecting outcome measures and enrolling patients.

Assessment of a mass balance equation for estimating community-level prevalence of COVID-19 using wastewater-based epidemiology in a mid-sized city

Wastewater-based epidemiology (WBE) has emerged as a valuable epidemiologic tool to detect the presence of pathogens and track disease trends within a community. WBE overcomes some limitations of traditional clinical disease surveillance as it uses pooled samples from the entire community, irrespective of health-seeking behaviors and symptomatic status of infected individuals. WBE has the potential to estimate the number of infections within a community by using a mass balance equation, however, it has yet to be assessed for accuracy. We hypothesized that the mass balance equation-based approach using measured SARS-CoV-2 wastewater concentrations can generate accurate prevalence estimates of COVID-19 within a community. This study encompassed wastewater sampling over a 53-week period during the COVID-19 pandemic in Gainesville, Florida, to assess the ability of the mass balance equation to generate accurate COVID-19 prevalence estimates. The SARS-CoV-2 wastewater concentration showed a significant linear association (Parameter estimate = 39.43, P value < 0.0001) with clinically reported COVID-19 cases. Overall, the mass balance equation produced accurate COVID-19 prevalence estimates with a median absolute error of 1.28%, as compared to the clinical reference group. Therefore, the mass balance equation applied to WBE is an effective tool for generating accurate community-level prevalence estimates of COVID-19 to improve community surveillance.

Wastewater surveillance for SARS-CoV-2 in a small coastal community: Effects of tourism on viral presence and variant identification among low prevalence populations

Wastewater-based epidemiology has been used to measure SARS-CoV-2 prevalence in cities worldwide as an indicator of community health, however, few longitudinal studies have followed SARS-CoV-2 in wastewater in small communities from the start of the pandemic or evaluated the influence of tourism on viral loads. Therefore the objective of this study was to use measurements of SARS-CoV-2 in wastewater to monitor viral trends and variants in a small island community over a twelve-month period beginning May 1, 2020, before the community re-opened to tourists. Wastewater samples were collected weekly and analyzed to detect and quantify SARS-CoV-2 genome copies. Sanger sequencing was used to determine genome sequences from total RNA extracted from wastewater samples positive for SARS-CoV-2. Visitor data was collected from the local Chamber of Commerce. We performed Poisson and linear regression to determine if visitors to the Cedar Key Chamber of Commerce were positively associated with SARS-CoV-2-positive wastewater samples and the concentration of SARS-CoV-2 RNA. Results indicated that weekly wastewater samples were negative for SARS-CoV-2 until mid-July when positive samples were recorded in four of five consecutive weeks. Additional positive results were recorded in November and December 2020, as well as January, March, and April 2021. Tourism data revealed that the SARS-CoV-2 RNA concentration in wastewater increased by 1.06 Log₁₀ genomic copies/L per 100 tourists weekly. Sequencing from six positive wastewater samples yielded two complete sequences of SARS-CoV-2, two overlapping sequences, and two low yield sequences. They show arrival of a new variant SARS-CoV-2 in January 2021. Our results demonstrate the utility of wastewater surveillance for SARS-CoV-2 in a small community. Wastewater surveillance and viral genome sequencing suggest that population mobility likely plays an important role in the introduction and circulation of SARS-CoV-2 variants among communities experiencing high tourism and who have a small population size.

Hydroxyl functionalized multi-walled carbon nanotubes modulate immune responses without increasing 2009 pandemic influenza A/H1N1 virus titers in infected mice

Growing use of carbon nanotubes (CNTs) have garnered concerns regarding their association with adverse health effects. Few studies have probed how CNTs affect a host's susceptibility to pathogens, particularly respiratory viruses. We reported that exposure of lung cells and mice to pristine single-walled CNTs (SWCNTs) leads to significantly increased influenza virus H1N1 strain A/Mexico/4108/2009 (IAV) titers in concert with repressed antiviral immune responses. In the present study, we investigated if hydroxylated multi-walled CNTs (MWCNTs), would result in similar outcomes. C57BL/6 mice were exposed to 20 μg MWCNTs on day 0 and IAV on day 3 and samples were collected on day 7. We investigated pathological changes, viral titers, immune-related gene expression in lung tissue, and quantified differential cell counts and cytokine and chemokine levels in bronchoalveolar lavage fluid. MWCNTs alone caused mild inflammation with no apparent changes in immune markers whereas IAV alone presented typical infection-associated inflammation, pathology, and titers. The co-exposure (MWCNTs + IAV) did not alter titers or immune cell profiles compared to the IAV only but increased concentrations of IL-1β, TNFα, GM-CSF, KC, MIPs, and RANTES and inhibited mRNA expression of Tlr3, Rig-i, Mda5, and Ifit2. Our findings suggest MWCNTs modulate immune responses to IAV with no effect on the viral titer and modest pulmonary injury, a result different from those reported for SWCNT exposures. This is the first study to show that MWCNTs modify cytokine and chemokine responses that control aspects of host defenses which may play a greater role in mitigating IAV infections.

Mimicking the human respiratory system: Online in vitro cell exposure for toxicity assessment of welding fume aerosol

In assessing the biological impact of airborne particles in vitro, air-liquid interface (ALI) exposure chambers are increasingly preferred over classical submerged exposure techniques, albeit historically limited by their inability to deliver sufficient aerosolized dose. A novel ALI system, the Dosimetric Aerosol in Vitro Inhalation Device (DAVID), bioinspired by the human respiratory system, uses water-based condensation for highly efficient aerosol deposition to ALI cell culture. Here, welding fumes (well-studied and inherently toxic ultrafine particles) were used to assess the ability of DAVID to generate toxicological responses between differing welding conditions. After fume exposure, ALI-cultured cells showed reductions in viability that were both distinct between welding conditions and linearly dose-dependent with respect to exposure time; comparatively, submerged cell cultures ran in parallel did not show these trends across exposure levels. DAVID delivers a substantial dose in minutes (> 100 μg/cm2), making it preferable over previous ALI systems, which require hours of exposure to deliver sufficient dose, and over submerged techniques, which lack comparable physiological relevance. DAVID has the potential to provide the most accurate assessment of in vitro toxicity yet from the perspectives of physiological relevance to the human respiratory system and efficiency in collecting ultrafine aerosol common to hazardous exposure conditions.

1129 Sex Dependent Effects on Sleep Architecture After Traumatic Brain Injury: Impact on Outcome

Introduction

Traumatic Brain Injury (TBI) is frequently associated with problems with sleep and diurnal somnolence. After determining if subjective somnolence was associated with sleep disturbances, we investigated if alterations in sleep architecture were associated with cognitive, social and emotional health in a sex dependent manner. For patients receiving positive airway pressure (PAP) treatment, we determined if lack of compliance contributed to cognitive and quality of life issues.

Methods

Adult TBI subjects (n=57) were assessed via overnight polysomnography. Mean age was 41 years and mean TBI chronicity was 2.5 years. Overall level of disability was determined by the Mayo Portland Inventory II. Sleep measures included slow wave sleep (SWS), REM latency, percent time in all sleep stages, apnea/hypopnea index, wake after sleep onset (WASO), and arousal index. Outcome measures were the California Verbal Learning Test (CVLT), Montreal Cognitive Assessment (MoCA), Trails A and B, Beck Depression Inventory, and Neuro-QoL.

Results

No sex effects for reporting somnolence were found. Besides being associated with increased subjective anxiety and stigma, somnolence was associated with increased arousals, decreases in SWS and higher incidence of REM AHI. WASO and number of arousals had a negative impact on the amount of SWS and sleep efficiency. Men spent significantly more time in REM sleep, which was correlated with higher scores on the MoCA and CVLT. Women showed more disability. Longer latencies to SWS were associated with increased CVLT performance. AHI was associated with increases in emotional/behavioral dyscontrol, fatigue and self-reported sleep disturbance. All effects were statistically significant.

Conclusion

Female TBI patients show significant impairments in REM sleep, which may impact learning and memory. Sleep disturbances were associated with poorer cognitive performance and may ultimately affect outcome, as indicated by lower scores on quality of life measures.

Support

Centre for Neuro Skills

1139 Sleep Disturbances In Chronic Stroke Patients: Emotional And Cognitive Impact

Introduction

The objective was to investigate the impact of sleep-wake disturbances (SWD) on cognition and quality of life in the post-acute phase of stroke.

Methods

Adult stroke (n=92) patients were assessed for SWD via overnight polysomnography. The mean age was 52 ± 1 years and mean latency from injury was 117 ± 10 days. Sleep measures included total sleep time (TST), sleep and REM latency, percent time in sleep stages, apnea/hypopnea index (AHI), wake after sleep onset (WASO), and arousal index. The primary cognitive/outcome measures were: Montreal Cognitive Assessment (MoCA), California Verbal Learning Test (CVLT-II), Neuro-QoL and Mayo Portland Adaptability Inventory (MPAI).

Results

Women had lower AHI (F(1,88)=9.360, p&lt;.01), fewer arousals (F(1,90)=4.53, p&lt;.05), and spent significantly more time in SWS (F(1,90)=11.525, p&lt;.001) than men; however, SWS was reduced in both sexes. SWS made up &lt; 3% of TST in 60% of patients and was not correlated with higher AHI. SWDs negatively impacted subjective quality of life (NeuroQOL). Longer latencies to sleep were associated with increased depression (p&lt;.05) and decreased positive affect (p&lt;.01). Increased sleep efficiency led to improved positive affect (p&lt;.05) and decreases in emotional/behavioral dyscontrol (p&lt;.05). Increased time in REM sleep decreased emotional/behavioral dyscontrol (p&lt;.05), while increasing satisfaction with social roles and activities(p&lt;.01). SWDs also negatively impacted cognitive/outcome scores. Increased TST and sleep efficiency led to higher scores on CVLT-II list B and long delay free recall (p&lt;.05), while higher AHI led to poorer performance on long delay and forced choice recognition trials (p&lt;.01). Additionally, non-REM AHI negatively impacted MPAI adjustment scores (F(1,69)=4.036, p&lt;.05).

Conclusion

Male stroke patients displayed significantly more arousals and spent less time in SWS than females. For both sexes, better sleep indicated improved quality of life. Sleep measures were correlated with cognitive/outcome measures. Non-REM AHI significantly predicted outcome at discharge from rehabilitation facility.

Support

 

Single-walled carbon nanotubes repress viral-induced defense pathways through oxidative stress

Exposure of lung cells in vitro or mice to single-walled carbon nanotubes (SWCNTs) directly to the respiratory tract leads to a reduced host anti-viral immune response to infection with influenza A virus H1N1 (IAV), resulting in significant increases in viral titers. This suggests that unintended exposure to nanotubes via inhalation may increase susceptibility to notorious respiratory viruses that carry a high social and economic burden globally. However, the molecular mechanisms that contribute to viral susceptibility have not been elucidated. In the present study, we identified the retinoic acid-induced gene I (RIG-I) like receptors (RLRs)/mitochondrial antiviral signaling (MAVS) pathway as a target of SWCNT-induced oxidative stress in small airway epithelial cells (SAEC) that contribute to significantly enhanced influenza viral titers. Exposure of SAEC to SWCNTs increases viral titers while repressing several aspects of the RLR pathway, including mRNA expression of key genes (e.g. IFITs, RIG-I, MDA5, IFNβ1, CCL5). SWCNTs also reduce mitochondrial membrane potential without altering oxygen consumption rates. Our findings also indicate that SWCNTs can impair formation of MAVS prion-like aggregates, which is known to impede downstream activation of the RLR pathway and hence the transcriptional production of interferon-regulated anti-viral genes and cytokines. Furthermore, application of the antioxidant NAC alleviates inhibition of gene expression levels by SWCNTs, as well as MAVS signalosome formation, and increased viral titers. These data provide evidence of targeted impairment of anti-viral signaling networks that are vital to immune defense mechanisms in lung cells, contributing to increased susceptibility to IAV infections by SWCNTs.

Single-walled carbon nanotubes modulate pulmonary immune responses and increase pandemic influenza a virus titers in mice

Background

Numerous toxicological studies have focused on injury caused by exposure to single types of nanoparticles, but few have investigated how such exposures impact a host’s immune response to pathogen challenge. Few studies have shown that nanoparticles can alter a host’s response to pathogens (chiefly bacteria) but there is even less knowledge of the impact of such particles on viral infections. In this study, we performed experiments to investigate if exposure of mice to single-walled carbon nanotubes (SWCNT) alters immune mechanisms and viral titers following subsequent influenza A virus (IAV) infection.

Methods

Male C57BL/6 mice were exposed to 20 μg of SWCNT or control vehicle by intratracheal instillation followed by intranasal exposure to 3.2 × 10⁴ TCID₅₀ IAV or PBS after 3 days. On day 7 mice were euthanized and near-infrared fluorescence (NIRF) imaging was used to track SWCNT in lung tissues. Viral titers, histopathology, and mRNA expression of antiviral and inflammatory genes were measured in lung tissue. Differential cell counts and cytokine levels were quantified in bronchoalveolar lavage fluid (BALF).

Results

Viral titers showed a 63-fold increase in IAV in SWCNT + IAV exposed lungs compared to the IAV only exposure. Quantitation of immune cells in BALF indicated an increase of neutrophils in the IAV group and a mixed profile of lymphocytes and neutrophils in SWCNT + IAV treated mice. NIRF indicated SWCNT remained in the lung throughout the experiment and localized in the junctions of terminal bronchioles, alveolar ducts, and surrounding alveoli. The dual exposure exacerbated pulmonary inflammation and tissue lesions compared to SWCNT or IAV single exposures. IAV exposure increased several cytokine and chemokine levels in BALF, but greater levels of IL-4, IL-12 (P70), IP-10, MIP-1, MIP-1α, MIP-1β, and RANTES were evident in the SWCNT + IAV group. The expression of tlr3, ifnβ1, rantes, ifit2, ifit3, and il8 was induced by IAV alone but several anti-viral targets showed a repressed trend (ifits) with pre-exposure to SWCNT.

Conclusions

These findings reveal a pronounced effect of SWCNT on IAV infection in vivo as evidenced by exacerbated lung injury, increased viral titers and several cytokines/chemokines levels, and reduction of anti-viral gene expression. These results imply that SWCNT can increase susceptibility to respiratory viral infections as a novel mechanism of toxicity.

Electronic supplementary material

The online version of this article (10.1186/s12985-017-0909-z) contains supplementary material, which is available to authorized users.

Serotonin 1B Receptors Regulate Prefrontal Function by Gating Callosal and Hippocampal Inputs

Both medial prefrontal cortex (mPFC) and serotonin play key roles in anxiety; however, specific mechanisms through which serotonin might act on the mPFC to modulate anxiety-related behavior remain unknown. Here, we use a combination of optogenetics and synaptic physiology to show that serotonin acts presynaptically via 5-HT1B receptors to selectively suppress inputs from the contralateral mPFC and ventral hippocampus (vHPC), while sparing those from mediodorsal thalamus. To elucidate how these actions could potentially regulate prefrontal circuit function, we infused a 5-HT1B agonist into the mPFC of freely behaving mice. Consistent with previous studies that have optogenetically inhibited vHPC-mPFC projections, activating prefrontal 5-HT1B receptors suppressed theta-frequency mPFC activity (4-12 Hz), and reduced avoidance of anxiogenic regions in the elevated plus maze. These findings suggest a potential mechanism, linking specific receptors, synapses, patterns of circuit activity, and behavior, through which serotonin may regulate prefrontal circuit function, including anxiety-related behaviors.

Where does the Albumin go? Human Albumin Solution usage following the implementation of a demand management programme

OBJECTIVE

To outline the Guy's and St Thomas' NHS Foundation Trust (GSTFT) and Evelina London Children's Hospital (ELCH) demand management plan for human albumin solution (HAS) and usage.

BACKGROUND

There is no UK-wide guidance governing the use of HAS. A severe shortage in 2015 prompted a Trust demand management programme. Indications were categorised according to locally agreed colour code and ASFA categories.

METHODS

Following the implementation of the demand management programme, a 6-month audit of HAS usage was completed.

RESULTS

A total of 1303.1 L of HAS was used in 1139 infusions; 737 infusions were 20% HAS, accounting for 175.7 L (13.5%) in 181 patients. Indications for 20% HAS were red in 53.9% (94.7 L), blue in 26.5% (46.5 L) and grey in 19.6% (34.5 L). The remaining 1127.4 L (86.5%) infused were of 4.5 and 5 % HAS. A total of 1102.3 L (97.8%) was used for plasma exchange, 941.4 L (85.4%) ASFA category I, 93.7 L (8.5%) category II, 25.5 L (2.3%) category IV and 41.7 L (3.8%) for indications not specified according to ASFA; 25.1 L (2.2%) were used for a grey indication (volume resuscitation for hypovolaemia).

CONCLUSIONS

The demand management programme provides surveillance of indications and retrospective verification of appropriate use. The majority of HAS indications were appropriate. Plasma exchange accounted for 84.6% of HAS usage and will be the focus of further demand management strategies. The demand management programme whilst aiming to promote best transfusion practice also ensures a tool to manage future shortages according to indication and available supply.

Influence of the Gastrointestinal Environment on the Bioavailability of Ethinyl Estradiol Sorbed to Single-Walled Carbon Nanotubes

Recent evidence suggests that, because of their sorptive nature, if single-walled carbon nanotubes (SWCNTs) make their way into aquatic environments, they may reduce the toxicity of other waterborne contaminants. However, few studies have examined whether contaminants remain adsorbed following ingestion by aquatic organisms. The objective of this study was to examine the bioavailability and bioactivity of ethinyl estradiol (EE2) sorbed onto SWCNTs in a fish gastrointestinal (GI) tract. Sorption experiments indicated that SWCNTs effectively adsorbed EE2, but the chemical was still able to bind and activate soluble estrogen receptors (ERs) in vitro. However, centrifugation to remove SWCNTs and adsorbed EE2 significantly reduced ER activity compared to that of EE2 alone. Additionally, the presence of SWCNTs did not reduce the extent of EE2-driven induction of vitellogenin 1 in vivo compared to the levels in organisms exposed to EE2 alone. These results suggest that while SWCNTs adsorb EE2 from aqueous solutions, under biological conditions EE2 can desorb and retain bioactivity. Additional results indicate that interactions with gastrointestinal proteins may decrease the level of adsorption of estrogen to SWCNTs by 5%. This study presents valuable data for elucidating how SWCNTs interact with chemicals that are already present in our aquatic environments, which is essential for determining their potential health risk.

The effects of continuous and pulsed exposures of suspended clay on the survival, growth, and reproduction of Daphnia magna

Suspended sediments are a natural component of aquatic ecosystems, but anthropogenic activity such as land development can result in significant increases, especially after rain events. Continuous exposures of suspended clay and silt have been shown to affect growth and reproduction of Cladocera, leading to a decrease in population growth rate. The mechanism of clay toxicity in these filter-feeding organisms is clogging of the gut tract, resulting in decreased food uptake and assimilation. When placed in clean water, daphnids can purge clay from their gut and recover. In many surface waters, aquatic organisms experience episodic exposures of high concentrations of suspended solids driven by rain events. However, little is known about the consequences of pulsed exposures on individuals and populations. The objective of the present study was to characterize the effects of continuous and pulsed exposures of natural and defined clays on survival, growth, and reproduction of Daphnia magna. Two defined clays, montmorillonite and kaolinite, as well as clay isolated from the Piedmont region of South Carolina, USA, were used. Continuous exposures of clays elicited a dose dependent decrease in survival. Toxicity varied depending on clay source with montmorillonite > natural clay > kaolinite. Pulsed exposures caused a decrease in survival in a 24 h exposure of 734 mg/L kaolinite. Exposure to 73.9 mg/L also caused an increase in the time to gravidity, although there was not a corresponding decrease in neonate production over 21 d. No significant effects resulted from 12 h exposures even at 730 mg/L, almost 10 times the 24-h reproductive effects concentration. This suggests that exposure duration impacted toxicity more than exposure concentration in these pulsed exposures.

Validation of the flash-evoked response from fetal MEG

Flash-evoked responses can be recorded from the fetus in utero. However, a standard analysis approach based on orthogonal projection (OP) to attenuate maternal and fetal cardiac signals leads to a spatial redistribution of the signal. This effect prevents the correlation of source location with a known fetal head location in some cases and the signal-to-noise ratio (SNR) is sometimes limited such that the response latency is difficult to determine. We used a modified beamformer model search analysis to avoid the redistribution shortcoming and to improve the SNR. We included a statistical test for residual interference in the average and quantified significance of the evoked response with a bootstrap method. Selected source locations compared favorably to fetal head locations estimated from ultrasound exams. The evoked response time course was found to have a significant post-trigger peak with a latency between about 180 and 770 ms in more than 90% of the subject measurements. These results confirm that the combined application of a beamformer model search and bootstrap significance test provides a validation of the flash-evoked response observed in OP processed fetal MEG channels.

Exploring the role of auction markets in cattle movements within Great Britain

Within Great Britain cattle are often traded at regional markets, of which there are approximately 200 located throughout England, Scotland and Wales. The movement of animals through markets was important in the spread of foot-and-mouth disease (FMD) virus during the 2001 GB outbreak. Here, we describe the movements of cattle to and from markets for 2002-2004 and, using social network analysis, we construct networks based on these movements. In 2002, 56,227 animal holdings (AH) sent cattle to 222 cattle auction markets, compared to 58,476 AH and 187 auction markets in 2004. Auction markets vary considerably in their trading with AH. The majority of markets received animals from less than 50 AH, but one received animals from as many as 6155 AH during a year. The distances travelled between origin AH and destination AH when cattle move "directly" were found to be significantly shorter compared to distances between origin and destination AH where the movement occurred via a market. However, the vast majority of distances moved, for both types of movements, were less than 50 km. Some auction markets appear as highly connected premises within the contact network and are associated with high betweenness scores. However AH also occupy positions central to the contact network. The variation in the characteristics and role of individual markets within the contact network suggests important differences in risk of disease transmission associated with each market. Inclusion of network parameters, when considering the risk associated with moving cattle through auction markets may enhance the development of effective targeted disease control strategies.

Recent network evolution increases the potential for large epidemics in the British cattle population

Following the foot and mouth disease epidemic in Great Britain (GB) in 2001, livestock movement bans were replaced with mandatory periods of standstill for livestock moving between premises. It was anticipated that these movement restrictions would limit each individual's contact networks, the extent of livestock movements and thus the spread of future disease outbreaks. However, the effect of behaviour changes on the global network in adapting to these restrictions is currently unknown. Here, we take a novel approach using GB cattle movement data to construct week-by-week contact networks between animal holdings (AH) to explore the evolution of the network since this policy was introduced, the first time network theory has been used for this purpose. We show that the number of AH moving cattle as part of the giant strong component (GSC), representing the region of maximal connectivity, has been increasing linearly over time. This is of epidemiological significance as the size of the GSC indicates the number of holdings potentially exposed to disease, thus giving a lower bound of maximum epidemic size. Therefore, despite restriction of cattle movements, emergent behaviour in this self-organizing system has potentially increased the size of infectious disease epidemics within the cattle industry.

Nicotine Dependence and Reward Differ between Adolescent and Adult Male Mice

The present study defined age differences in several aspects of nicotine dependence using male mice of two age groups [postnatal day (PND) 28 and PND 70]. Adolescent and adult mice displayed differences in acute sensitivity to nicotine, rewarding and withdrawal effects, development of tolerance to nicotine, and nicotinic receptor function. In the condition place preference model, adolescent mice displayed a higher sensitivity to nicotine than adults. In addition, in spontaneous and mecamylamine-precipitated withdrawal models, adolescent mice displayed fewer withdrawal signs than adults. In response to acute nicotine, it was found that adolescent mice displayed greater nicotine-induced antinociception compared with adult counterparts in the tail-flick test. Furthermore, differences in tolerance to nicotine were also noted in that adolescents developed a significantly higher degree of tolerance to nicotine in the hot-plate test compared with adults. Finally, using rubidium efflux assays, it was found that adolescent nicotinic receptors in different brain areas displayed significantly increased functionality compared with adult receptors. These data indicate that the underlying receptor mechanisms of nicotine dependence differ for adults and adolescents, suggesting that the effectiveness of smoking cessation therapies will differ for various age groups.

Searching for the best model: ambiguity of inverse solutions and application to fetal magnetoencephalography

Fetal brain signals produce weak magnetic fields at the maternal abdominal surface. In the presence of much stronger interference these weak fetal fields are often nearly indistinguishable from noise. Our initial objective was to validate these weak fetal brain fields by demonstrating that they agree with the electromagnetic model of the fetal brain. The fetal brain model is often not known and we have attempted to fit the data to not only the brain source position, orientation and magnitude, but also to the brain model position. Simulation tests of this extended model search on fetal MEG recordings using dipole fit and beamformers revealed a region of ambiguity. The region of ambiguity consists of a family of models which are not distinguishable in the presence of noise, and which exhibit large and comparable SNR when beamformers are used. Unlike the uncertainty of a dipole fit with known model plus noise, this extended ambiguity region yields nearly identical forward solutions, and is only weakly dependent on noise. The ambiguity region is located in a plane defined by the source position, orientation, and the true model centre, and will have a diameter approximately 0.67 of the modelled fetal head diameter. Existence of the ambiguity region allows us to only state that the fetal brain fields do not contradict the electromagnetic model; we can associate them with a family of models belonging to the ambiguity region, but not with any specific model. In addition to providing a level of confidence in the fetal brain signals, the ambiguity region knowledge in combination with beamformers allows detection of undistorted temporal waveforms with improved signal-to-noise ratio, even though the source position cannot be uniquely determined.

Automated localization of magnetoencephalographic interictal spikes by adaptive spatial filtering

OBJECTIVE

Automated adaptive spatial filtering techniques can be applied to magnetoencephalographic (MEG) data collected from people with epilepsy. Source waveforms estimated by these methods have higher signal-to-noise ratio (SNR) than spontaneous MEG data, allowing identification and location of interictal spikes. The software tool SAM(g(2)) provides an adaptive spatial filtering algorithm for MEG data that yields source images of excess kurtosis and provides source time-courses in voxels exhibiting high excess kurtosis. The sensitivity and specificity of SAM(g(2)) in epilepsy is unknown.

METHODS

Interictal MEG data from 36 patients with intractable epilepsy were analyzed using SAM(g(2)), and results compared with equivalent current dipole (ECD) fit procedures.

RESULTS

When SNR of interictal spikes was high (compared to background) with a clear single focus, in most cases there was good agreement between ECD and SAM(g(2)). With multiple foci, there was typically overlap but imperfect concordance between results of ECD and SAM(g(2)).

CONCLUSIONS

SAM(g(2)) may in some cases be equivalent to manual ECD fit for localizing interictal spikes with single locus and good SNR. Further studies are required to validate SAM(g(2)) with multiple foci or poor SNR.

SIGNIFICANCE

In some cases, SAM(g(2)) might eventually assist or replace manual ECD analysis of MEG data.

Optimal reduction of MCG in fetal MEG recordings

Recording fetal magnetoencephalographic (fMEG) signals in-utero is a demanding task due to biological interference, especially maternal and fetal magnetocardiographic (MCG) signals. A method based on orthogonal projection of MCG signal space vectors (OP) was evaluated and compared with independent component analysis (ICA). The evaluation was based on MCG amplitude reduction and signal-to-noise ratio of fetal brain signals using exemplary datasets recorded during ongoing studies related to auditory evoked fields. The results indicate that the OP method is the preferable approach for attenuation of MCG and for preserving the fetal brain signals in fMEG recordings.

Right parietal activation during delusional state in episodic interictal psychosis of epilepsy: a report of two cases

Magnetoencephalography (MEG) was used to image brain activity associated with delusions in episodic interictal psychosis of epilepsy. Two female patients aged 65 and 68 with temporal lobe epilepsy were studied during and after a delusional state. Topographic images of the excess kurtosis (g2), the statistical index of spikelike activity, were obtained from unaveraged MEG recordings using an analysis called "synthetic aperture magnetometry" (SAM). For both patients, MEG waveforms and excess kurtosis images revealed spiky activity in the right inferior parietal region during the delusional state. A second MEG measurement after delusions were resolved with antipsychotic therapy revealed no excess kurtosis in the right parietal area. Likewise, the sharp waves on MEG recordings disappeared as well. Our results suggest association of the right inferior parietal cortex, including the supramarginal gyrus, with the delusional state of episodic interictal psychosis of epilepsy.

Quantifying Uncertainty Associated with Microbial Count Data: A Bayesian Approach

We consider the problem of estimating bacterial concentration in a substance, given microbial count data. A Bayesian approach is proposed which naturally allows the incorporation of both plate-count data and extra information from confirmatory tests such as genotyping by polymerase chain reaction (PCR). The estimation methods yield posterior credible regions for bacterial concentration, in contrast to the previous methods, which generally only produce point estimates. The approach is illustrated with specific reference to the enumeration of the food-borne pathogen Escherichia coli O157 by spiral plating, although the methodology can be applied to any bacterium or counting method of interest. The results obtained provide guidance to the experimenter as to the number of confirmatory tests which should be performed, and also suggest that in the initial plate count one should err on the side of including rather than excluding colonies whose genotype seems unclear.

SAM(g2) analysis for detecting spike localization: a comparison with clinical symptoms and ECD analysis in an epileptic patient

SAM(g2) analysis, a combination of synthetic aperture magnetometry (SAM) and excess kurtosis (g2) method, is a novel epilepsy analysis procedure based on a spatial filtering technique. By producing a three-dimensional image of the g2 values and superimposing them onto a patient's MR images, this analysis can automatically estimate spike localization from raw MEG epilepsy signals including spikes. The aim of this study is to examine SAM(g2) analysis using MEG signals of an epileptic patient, whose clinical symptoms of colored elementary visual auras had ceased in accordance with the changes of the estimated localizations of the equivalent current dipoles (ECDs) of the interictal spikes. His visual auras were experienced in 1997, while they ceased in 1999 with effective medication. The patient provided written informed consent for the experimental procedures. The MEG signals were recorded in 1997 and 1999, and were analyzed using both ECD and SAM(g2) analyses. For the MEG signals of 1997, ECD analysis estimated most of the interictal spikes in the right fusiform and inferior temporal gyri, which subserve human color processing. SAM(g2) analysis also estimated them in the same areas. For those of 1999, both ECD and SAM(g2) analyses estimated them in the right transverse gyrus of Heschl. As well as ECD analysis, SAM(g2) analysis successfully estimated the changes of the localizations of the interictal spikes in accordance with the changes of the patient's clinical symptoms, indicating that SAM(g2) analysis is useful for detection of interictal spike localization in epileptic patients.

Localization of interictal spikes using SAM(g2) and dipole fit

SAM(g2) is an automated analysis that transforms the MEG data into a functional image of spike-like activity, giving the source waveforms for those locations. Since the source waveforms estimated by SAM have higher signal-to-noise ratio (SNR) than does the raw MEG data, it is possible to automatically mark the location and timing of each spike for comparisons with dipole fit procedures. Both SAM(g2) and equivalent current dipole (ECD) fits were used to analyze MEG interictal spike recordings in 10 patients with cortical dysplasias and medial temporal lobe epilepsy. The ECD fit locations obtained by manual spike classification and latency marking were compared with those found by automated SAM(g2) procedures. When the SNR of interictal activity was high (compared to the background) with a clear single focus, there was excellent agreement between the ECD cluster location and the SAM(g2) maximum. However, when the SNR of spikes was low, manual single ECD location scatter was larger than SAM(g2) reconstructions. When multiple independent interictal spike loci were present, there was some disagreement between SAM(g2) and ECD scatter in the cases of low SNR spikes. When SAM(g2) indicated multiple coupled spike loci, the residual variance for the dipole fit was high and its scatter unacceptably large--even for multiple dipole models. This study demonstrates that SAM(g2) is equivalent to ECD fit for localizing interictal spikes when there is a single locus and good SNR. Further studies are required to validate cases in which there are multiple spike loci or poor SNR.

How many channels are needed for MEG?

Channel count in modern MEG systems has been steadily increasing, but are more channels necessary? Assuming that the spatial sampling considerations are satisfied, this question can be answered by examining the MEG system's ability to localize and resolve brain sources. For the simple situation where only uncorrelated sensor noise is present, dipole localization accuracy monotonically increases with increasing number of channels, while for spatially correlated brain noise the accuracy increases only until the number of channels reaches 100 to 200. Beyond this limit the inter-channel separation is comparable to the brain noise correlation distance and increasing the channel count does not help. Contrary to the above dipole result, we show by simulations with up to several thousand channels, that if the data is analyzed by beamformers even in the presence of correlated brain noise, the two-source resolvability and single-source localization accuracy monotonically improve with increasing number of channels. We demonstrate such behavior for a 275 channels system, where we have inserted an artificial dipole into real measured brain noise and resampled the number of channels to 138. Beamformer analysis of the data shows markedly improved localization accuracy when the number of channels is increased from 138 to 275. This finding also signifies that the beamformer performance is not limited by system imperfections when the number of channels is as large as 275. To clarify these results, we illustrate analytically the mechanism of beamformer resolution dependence on the number of channels, using an example of a simple system containing two dipole sources, and uncorrelated sensor noise.

Advanced electronics for the CTF MEG system

Development of the CTF MEG system has been advanced with the introduction of a computer processing cluster between the data acquisition electronics and the host computer. The advent of fast processors, memory, and network interfaces has made this innovation feasible for large data streams at high sampling rates. We have implemented tasks including anti-alias filter, sample rate decimation, higher gradient balancing, crosstalk correction, and optional filters with a cluster consisting of 4 dual Intel Xeon processors operating on up to 275 channel MEG systems at 12 kHz sample rate. The architecture is expandable with additional processors to implement advanced processing tasks which may include e.g., continuous head localization/motion correction, optional display filters, coherence calculations, or real time synthetic channels (via beamformer). We also describe an electronics configuration upgrade to provide operator console access to the peripheral interface features such as analog signal and trigger I/O. This allows remote location of the acoustically noisy electronics cabinet and fitting of the cabinet with doors for improved EMI shielding. Finally, we present the latest performance results available for the CTF 275 channel MEG system including an unshielded SEF (median nerve electrical stimulation) measurement enhanced by application of an adaptive beamformer technique (SAM) which allows recognition of the nominal 20-ms response in the unaveraged signal.

Localization of event-related activity by SAM(erf)

Synthetic aperture magnetometry (SAM) has been used to image source power or source signal-to-noise ratio from MEG. However, the locations of maximal event-related oscillatory activity (or changes from resting state) do not necessarily coincide with those sites that are phase-locked to external events (i.e., localized by dipole fit to the averaged evoked response). Since an estimate of the source time-series may also be obtained by applying the beamformer coefficients to the MEG signal, one can image event-related activity by mapping some function reflecting the reliability of the averaged source waveform at each location. We have devised a new analysis method, SAM(erf), for obtaining a functional image of event-related brain activity and revealing the corresponding waveforms for activated sites. The mapping function used is the ratio of RMS amplitude of the averaged source waveform to that of the +/- average waveform, for a selected time window. This function is computed at each coordinate on a three-dimensional grid in the head. In addition to the SAM(erf) functional image, the averaged source waveforms for each local maximum in the image can be computed and displayed. This procedure can reveal multiple locations and waveforms at sites in the brain engaged in event-related activities. When this method is applied to evoked response studies, phase-locked activity can sometimes be found in areas distant from primary sensory cortex. Given the sensitivity of this functional imaging method to areas outside primary sensory cortex, it has the potential for detecting subtle changes in brain activity in health and disease.

Forward solution ambiguity for fMEG model

Accurate knowledge of the electromagnetic model of the fetal brain is required for quantitative fetal MEG (fMEG) signal analysis. The model is defined by the fetal head position, assuming that volume currents are confined to it. Head position can be located by 3D ultrasound. Since the ultrasound is presently not integrated with fMEG, there is a potential for fetal head motion when the mother moves between the two instruments. To interpret the fMEG data without accurate information about the fetal head position, a model search must be undertaken to localize not only the fMEG source within the fetal head, but also the fetal head within the maternal abdomen. Such model search results in multiple solutions with different source amplitudes, but with roughly the same fit errors [Vrba, 2004]. We show that this behaviour is caused by the forward solution ambiguity. For a given measurement, there is a large region within the maternal abdomen within which all fetal head centers produce reasonably good explanation of the observed signal. The source positions within these different fetal heads are different, but the resulting signals are indistinguishable in the presence of even a small noise. Similar ambiguity also exists in adult MEG, where it usually does not pose a problem because the head position is well known.

Cleaning fetal MEG using a beamformer search for the optimal forward model

We present a new method for improving the signal-to-noise ratio (SNR) of event-related fetal MEG signals based upon the SAM minimum-variance beamformer. SAM could separate the evoked response source activity from the remaining fMEG signal and interference if the evoked response source coordinates and forward model were know. However, this requires knowledge of both the coordinate of the evoked response source and its forward model. In late gestation, the vernix caseosa effectively insulates the fetus from the amniotic fluid. Hence, the forward model could be approximated by an equivalent current dipole in a homogeneously conducting sphere with its origin at the center of the fetal head. In the absence of accurate anatomical data, a beamformer could be used to evaluate all feasible source-origin combinations--selecting the combination giving the best SNR for the evoked response. Application of this approach to measured fMEG data reveals that the optimal model sphere location is described not by a single local sphere origin, but rather by all origins lying within an extended region. This result is explained by model predictions showing the same region of ambiguity [Vrba, 2004]. Although the model search does not localize the sources of the fetal evoked response, it does significantly improve SNR. This was demonstrated by analysis of fetal auditory evoked response data.

Intermittent and persistent shedding of Escherichia coli O157 in cohorts of naturally infected calves

AIMS

We conducted two short-term studies of cohorts of naturally infected calves to determine the prevalence and concentrations of Escherichia coli O157 shed in faeces.

METHODS AND RESULTS

Two cohorts of calves were sampled; in the first study 14 calves were sampled up to five times a day for 5 days; in the second study a group of 16 separate calves were sampled once or twice a day for 15 days. All cattle within the two cohorts shed E. coli O157 at some point during the respective studies. In 18% of samples, E. coli O157 could only be isolated using immunomagnetic separation after an enrichment period, suggesting concentrations <250 CFU g(-1). The highest concentrations recorded were 6.7 x 10(5) and 1.6 x 10(6) CFU g(-1) for studies 1 and 2 respectively.

CONCLUSIONS

Persistent, high shedders (shedding >10(3) CFU g(-1)) were evident in both studies but, in the majority of calves, the pathogen was isolated intermittently.

SIGNIFICANCE AND IMPACT OF THE STUDY

The variable patterns of shedding have important implications for the design of appropriate sampling protocols and for gaining meaningful estimates of parameters used in mathematical models of transmission.

Development and application of a spiral plating method for the enumeration of Escherichia coli O157 in bovine faeces

AIM

To develop and validate a direct plating method applicable to epidemiological studies for enumerating Escherichia coli O157 in cattle faeces.

METHODS AND RESULTS

The spiral plate count method was used to enumerate E. coli O157 in faecal samples. The accuracy and variation of counts was then assessed using faecal samples inoculated with E. coli O157. There was good agreement between inoculated levels of E. coli O157 and those recovered from faeces, particularly when counts were > 10(2) CFU g(-1) of faeces. The method was applied to a small study assessing short-term survival of E. coli O157 in naturally infected cattle faeces. E. coli O157 was found to survive in faeces for over 10 days at concentrations above 10(3) CFU g(-1) of faeces. Populations of E. coli O157 were also found to increase 100-fold in the first few hours after defecation.

CONCLUSIONS

The enumeration method is easy to implement and enables a quick throughput of large numbers of samples. The method is accurate and reliable and enables the inherent variation in count data to be explored but needs to be used in combination with a more sensitive method for samples containing < 10(2) CFU g(-1) of faeces.

SIGNIFICANCE AND IMPACT OF THE STUDY

The method described is appropriate for enumeration of E. coli O157 in cattle faeces in large-scale epidemiological studies.

Human fetal brain imaging by magnetoencephalography: verification of fetal brain signals by comparison with fetal brain models

Fetal magnetoencephalogram (fMEG) is measured in the presence of a large interference from maternal and fetal magnetocardiograms (mMCG and fMCG). This cardiac interference can be successfully removed by orthogonal projection of the corresponding spatial vectors. However, orthogonal projection redistributes the fMEG signal among channels. Such redistribution can be readily accounted for in the forward solution, and the signal topography can also be corrected. To assure that the correction has been done properly, and also to verify that the measured signal originates from within the fetal head, we have modeled the observed fMEG by two extreme models where the fetal head is assumed to be either electrically transparent or isolated from the abdominal tissue. Based on the measured spontaneous, sharp wave, and flash-evoked fMEG signals, we have concluded that the model of the electrically isolated fetal head is more appropriate for fMEG analysis. We show with the help of this model that the redistribution due to projection was properly corrected, and also, that the measured fMEG is consistent with the known position of the fetal head. The modeling provides additional confidence that the measured signals indeed originate from within the fetal head.

Cerebral motor control in patients with gliomas around the central sulcus studied with spatially filtered magnetoencephalography

OBJECTIVE

Application of spatially filtered magnetoencephalography (MEG) to investigate changes in the mechanism of cerebral motor control in patients with tumours around the central sulcus.

METHODS

MEG records were made during a repetitive hand grasping task in six patients with gliomas around the central sulcus and in four control subjects. Power decreases in the alpha (8-13 Hz), beta (13-30 Hz), and low gamma bands (30-50 Hz) during the motor tasks (event related desynchronisation, ERD) were analysed statistically with synthetic aperture magnetometry. The tomography of ERD was superimposed on the individual's magnetic resonance image.

RESULTS

beta ERD was consistently localised to the contralateral primary sensorimotor cortex (MI/SI) in control subjects, whereas the alpha and low gamma ERD showed considerable intersubject variability. beta ERD in patients during non-affected side hand movement was also localised to the contralateral MI/SI, but exclusively to the ipsilateral hemisphere during affected side hand movement.

CONCLUSIONS

The altered pattern of ERD in the patient group during affected side hand movement suggests recruitment of diverse motor areas, especially the ipsilateral MI/SI, which may be required for the effective movement of the affected hand.

Signal processing in magnetoencephalography

The subject of this article is detection of brain magnetic fields, or magnetoencephalography (MEG). The brain fields are many orders of magnitude smaller than the environmental magnetic noise and their measurement represent a significant metrological challenge. The only detectors capable of resolving such small fields and at the same time handling the large dynamic range of the environmental noise are superconducting quantum interference devices (or SQUIDs). The SQUIDs are coupled to the brain magnetic fields using combinations of superconducting coils called flux transformers (primary sensors). The environmental noise is attenuated by a combination of shielding, primary sensor geometry, and synthetic methods. One of the most successful synthetic methods for noise elimination is synthetic higher-order gradiometers. How the gradiometers can be synthesized is shown and examples of their noise cancellation effectiveness are given. The MEG signals measured on the scalp surface must be interpreted and converted into information about the distribution of currents within the brain. This task is complicated by the fact that such inversion is nonunique. Additional mathematical simplifications, constraints, or assumptions must be employed to obtain useful source images. Methods for the interpretation of the MEG signals include the popular point current dipole, minimum norm methods, spatial filtering, beamformers, MUSIC, and Bayesian techniques. The use of synthetic aperture magnetometry (a class of beamformers) is illustrated in examples of interictal epileptic spiking and voluntary hand-motor activity.

Effect of perinatal buprenorphine exposure on development in the rat

The developmental effects of exposure to various doses of buprenorphine, methadone, or water during the perinatal period were studied in the rat. Rats were exposed to buprenorphine (0.3, 1.0, or 3.0 mg/kg/day), methadone (9 mg/kg/day), and/or water prenatally, postnatally, or both pre- and postnatally, via maternally implanted osmotic minipumps. Fetal and maternal mortality and morbidity were assessed, as well as the acquisition of several developmental milestones, pup weight gain, precipitated withdrawal, and the antinociceptive effect of morphine. Although perinatal exposure to buprenorphine failed to produce severe maternal and fetal or neonatal mortality, it was associated with a significant amount of perinatal mortality and perturbations of pup development. Pups developed physical dependence to both drugs, as evidenced by the ability of naloxone challenge to precipitate withdrawal. Both drugs induced tolerance to the antinociceptive effects of morphine in the tail-flick test. The effects of buprenorphine varied with the dose used, and the highest dose did not always produce the greatest effect. There were some similarities between the effects of perinatal buprenorphine and perinatal methadone; however, differences were also observed between the effects of the two drugs, which may be related to the different affinities and efficacies of the drugs at different opioid receptor subtypes.

Perinatal opioids reduce striatal nerve growth factor content in rat striatum

Both human and animal models indicate that perinatal methadone exposure produces a variety of short- and long-term neurobehavioral consequences, including disruption of normal development of striatal cholinergic neurons. Despite this, methadone maintenance is a standard method of managing pregnant heroin addicts, and the opioid receptor partial agonist buprenorphine is under evaluation for the same use. We now report that perinatal administration of either methadone or buprenorphine reduces the content of the neurotrophic factor nerve growth factor (NGF) in rat striatum, which may explain the behavioral deficits observed. Furthermore, although NGF content is reduced, there are no corresponding reductions in striatal NGF mRNA.

Theta rhythm increases in left superior temporal cortex during auditory hallucinations in schizophrenia: a case report

Auditory hallucinations (AH), the perception of sounds and voices in the absence of external stimuli, remain a serious problem for a large subgroup of patients with schizophrenia. Functional imaging of brain activity associated with AH is difficult, since the target event is involuntary and its timing cannot be predicted. Prior efforts to image the patterns of cortical activity during AH have yielded conflicting results. In this study, MEG was used to directly image the brain electrophysiological events associated with AH in schizophrenia. We observed an increase in theta rhythm, as sporadic bursts, in the left superior temporal area during the AH states, whereas there was steady theta band activity in the resting state. The present finding suggests strong association of the left superior temporal cortex with the experience of AH in this patient. This is consistent with the hypothesis that AH arises from areas of auditory cortex subserving receptive language processing.

Challenges of recording human fetal auditory-evoked response using magnetoencephalography

OBJECTIVE

Our goals were to successfully perform fetal auditory-evoked responses using the magnetoencephalography technique, understand its problems and limitations, and propose instrument design modifications to improve the signal quality and success rate.

METHODS

Fetal auditory-evoked responses were recorded from four fetuses with gestational ages ranging from 33-40+ weeks. The signals were recorded using a gantry-based superconducting quantum interference device. Auditory stimulus was 1 kHz tone burst. The evoked signals were digitized and averaged over an 800 ms window.

RESULTS

After several trials of positioning and repositioning the subjects, we were able to record auditory-evoked responses in three out of the four fetuses. Since the superconducting quantum interference device array design was not shaped to fit over the mother's abdomen, we experienced difficulty in positioning the sensors over the fetal head.

CONCLUSIONS

Based on this pilot study, we propose instrument design that may improve signal quality and success rate of the fetal magnetic auditory-evoked response.

Movement-related desynchronization of the cerebral cortex studied with spatially filtered magnetoencephalography

Event-related desynchronization (ERD) within the alpha and beta bands on unilateral index finger extension and hand grasping was investigated on six normal volunteers with magnetoencephalography (MEG). A novel spatial filtering technique for imaging cortical source power, synthetic aperture magnetometry (SAM), was employed for the tomographic demonstration of ERD. SAM source image results were transformed into statistical parametric images. On the same hand grasping task, a functional MRI (fMRI) study was conducted on two subjects and compared with the ERD result. When the MEG data were analyzed with the fast Fourier transformation, power attenuation within the alpha and beta bands was evident on the contralateral sensorimotor area just prior to movement onset. The tomographic distribution of ERD was clearly obtained with SAM statistical imaging analysis. The equivalent current dipole (ECD) for the signal-averaged motor field was localized to the hemisphere contralateral to the hand movement, roughly at the center of the region displaying beta-band ERD. The signal increase on fMRI roughly colocalized with the ERD on the contralateral sensorimotor area. In conclusion, with the novel spatial filtering technique for the brain magnetic field, SAM, cortical regions contributing to ERD on finger movement were successfully demonstrated in a tomographic manner. The relative colocalization of the contralateral SAM ERD with ECD as well as the fMRI activation suggests that SAM is a practically useful technique to extract event-related signals from brain noise.

Effect of prenatal opioid exposure on cholinergic development

Opioid drugs such as methadone or buprenorphine are often used in the management of pregnant addicts. These drugs are generally thought of as nonteratogenic and preferable to repeated cycles of withdrawal in utero. However, evidence exists that perinatal exposure to these opioids delays and disrupts cholinergic development, particularly in the striatum. Acetylcholine (ACh) content and the expression of choline acetyltransferase protein and mRNA are reduced in the early postnatal period by prenatal opioid exposure in the rat. Although these indicators of the cholinergic phenotype return to normal levels over time, the activity of the cholinergic neurons remains disrupted, with a large increase in ACh turnover rate. The mechanism of these effects is unknown, but may involve changes in the expression of nerve growth factor, which is reduced by opioid exposure.

Developmental effects of intermittent prenatal exposure to 1,1,1-trichloroethane in the rat

The effects of daily three 1-h exposures to 7000 ppm 1,1,1-trichloroethane (TCE) on physical and behavioral development were examined in Sprague-Dawley rats exposed during the last week of gestation. A sham group was exposed to filtered air. Offspring of both groups were fostered to untreated dams. No significant group differences were detected in total maternal weight gain or food and water consumption, but differences were observed in initial litter characteristics, including a longer gestation period in the TCE group, a smaller number of litters delivered in the TCE group, and fewer live pups per litter in the TCE group. At birth, the total litter weight was less in the TCE group, but there was no significant difference in average pup weight. Pups prenatally exposed to TCE did not differ from shams in day of eye opening, pinnae detachment, or incisor eruption. The TCE group weighed less the first 2 weeks of life, was impaired in its ability to perform the inverted screen, negative geotaxis, and vertical screen tests, and had less forelimb grip strength. Locomotor activity was reduced in the TCE group, and the ratio of brain to body weight was reduced in TCE-exposed offspring. These data provide evidence for neurobehavioral teratogenicity of intermittent prenatal exposure to high concentrations of TCE in rats.

Medial prefrontal cortex generates frontal midline theta rhythm

Frontal midline theta rhythm (Fm theta) is a distinct theta activity of EEG in the frontal midline area that appears during concentrated performance of mental tasks in normal subjects and reflects focused attentional processing. To tomographically visualize the source current density distributions of Fm theta, we recorded Fm theta by using a 64-channel whole-head MEG system from four healthy subjects, and applied a new analysis method, synthetic aperture magnetometry (SAM), an adaptive beam forming method. Fm theta was observed in the MEG signals over the bilateral frontal regions. SAM analysis showed bilateral medial prefrontal cortices, including anterior cingulate cortex, as the source of Fm theta. This result suggests that focused attention is mainly related to medial prefrontal cortex.

Our healthier hospital? The challenge for nursing

AIM

This paper aims to explore the problems which are currently preventing hospital nurses from fulfilling their health promotion role, and makes recommendations for nursing managers.

BACKGROUND

Hospital nurses have a key role to play in meeting recent Government proposals, which aim to enhance health promotion and public health in the NHS.

KEY ISSUES

Lack of knowledge and skills, unhealthy hospital environments, poor collaboration, insufficient time and poor nursing management are impediments to hospital nurses promoting health.

CONCLUSIONS

Hospital nurse managers need to capitalize on government enthusiasm by supporting health promotion education for nursing staff improving the hospital environment and facilitating better interdisciplinary working.

Postnatal developmental regulation of neuronal nicotinic receptor subunit alpha 7 and multiple alpha 4 and beta 2 mRNA species in the rat

This study examined the postnatal development of neuronal nicotinic receptor (nAChR) alpha 7, alpha 4 and beta 2 subunit mRNA in the Sprague Dawley rat brain. The hippocampus, septum and cortex were removed on postnatal day 1 (P1), P7, P14, or P28 and analyzed by sex. Northern analysis of cortical and pooled hippocampal and septal total RNA with 32P-alpha-dCTP-labeled alpha 7, alpha 4 (recognizing alpha 4.1 and alpha 4.2 mRNA), and beta 2 nAChR cDNA probes identified three (2.4, 3.8 and 8.0 kb) alpha 4, four (3.5, 5.0, 7.5 and 10.0 kb) beta 2 and a single 5.7 kb alpha 7 mRNA species. Cortical alpha 4 mRNA peaked on P14 and remained high on P28, whereas hippocampal/septal alpha 4 mRNA was higher on P7 and P14 than on P1 and P28. Expression of cortical and hippocampal/septal beta 2 mRNAs decreased on P7, followed by a dramatic peak on P14. alpha 7 mRNA peaked on P7. Throughout development, 2.4 kb alpha 4 mRNA was more intense than 3.8 kb alpha 4 mRNA, whereas 5.0 kb beta 2 mRNA was the most intense cortical and hippocampal/septal beta 2 mRNA species. The alpha 4.1-specific cDNA probe detected similar-sized alpha 4 bands as the pan-specific alpha 4 cDNA probe, therefore precluding the identification of any band as alpha 4.2-specific. These results suggest that postnatal expression of alpha 4 and alpha 7 but not beta 2 mRNAs is brain region-specific, and that the contribution of multiple nAChR subunit mRNA species in development may vary.