Validation of electronic diagnostic codes for rapid eye movement sleep behavior disorder

We investigated the accuracy of International Classification of Diseases (ICD) codes for the identification of Veterans with rapid eye movement (REM) sleep behavior disorder (RBD). The charts of 139 randomly sampled Veterans with ≥1 ICD-9 and ICD-10 code(s) for RBD were reviewed for documentation of a suspected, previous, or current diagnosis; clinical symptoms; and/or empiric treatments for this disorder. Notably, 71 (51.1%) of patients with RBD electronic diagnoses lacked polysomnography (PSG), and 29 (20.9%) had PSG reports without commentary on REM sleep without atonia (RSWA). Sleep centers are therefore encouraged to include a brief sentence in PSG report templates commenting on the presence/absence of RSWA.

Rates and Predictors of Rapid Eye Movement Sleep Behavior Disorder Symptoms Among Post-9/11 Veterans

OBJECTIVE

Posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI), which are prevalent conditions among post-9/11 veterans, increase risks of rapid eye movement (REM) sleep behavior disorder (RBD) and degenerative synucleinopathy. Rates and predictors of RBD symptoms were investigated by screening post-9/11 veterans for RBD with a validated questionnaire.

METHODS

In this cross-sectional analysis, consecutive patients in the Houston Translational Research Center for TBI and Stress Disorders (TRACTS) were screened with the English translation of the RBD Questionnaire-Hong Kong (RBDQ-HK). In addition to data from the standard TRACTS battery, systematic chart review was used to identify known sleep disorders mimicking or manifesting RBD.

RESULTS

Of the 119 patients with available RBDQ-HK scores, 71 (60%) and 65 (55%) screened positive for RBD, when a total score ≥21 and a factor 2 score ≥8 were used as cutoff scores, respectively. Univariable analyses with both cutoffs showed consistent associations between a positive RBDQ-HK screen and global sleep quality, number of TBI exposures, and PTSD severity. Multivariable logistic regression with total score ≥21 as a cutoff indicated that PTSD severity (odds ratio=1.06, 95% CI=1.02-1.10) and number of TBIs (odds ratio=1.63, 95% CI=1.16-2.41) were independent predictors of a positive screen, whereas global sleep quality was no longer significant. Multivariable logistic regression with factor 2 score ≥8 as a cutoff showed similar results.

CONCLUSIONS

Interdisciplinary parasomnia assessment, further validation of RBD screens, and standardized reporting of REM sleep without atonia could provide necessary information on the pathophysiological relationships linking PTSD, TBI, RBD symptoms, and ultimately synucleinopathy risk among post-9/11 veterans.

Physical Violence and Aggression in Parkinson's Disease: A Systematic Review

BACKGROUND

Physical violence and aggression (PVA), defined as behaviors with the potential to cause bodily injury, are unfortunate risks in the management of all-cause neurodegenerative dementias. While dementia in Parkinson's disease (PD) may not be evident for many years after clinical onset, neuropsychiatric disturbances occur at all stages of the disease. At issue is whether PVA in PD is associated with clinical factors that can be targets for prevention and management in the absence of a prevailing dementia syndrome.

OBJECTIVE

This systematic review examined the extent to which PVA in PD without dementia is a clinically significant concern and whether it is associated with factors that could warrant proactive management.

METHODS

A systematic search of 9 electronic databases used MeSH headings and equivalent terms for PD, aggression, and violence. Eligible manuscripts were original articles that were published in peer-reviewed journals and reported on adults with PD in the awake state with PVA as possible outcomes. Extracted data included study design, PD ascertainment methods and characteristics, PVA assessment methods, subject demographics, psychiatric and medical comorbidities, and pertinent results. Inciting and confounding factors were extracted from case reports. Quality assessment tools were applied in accordance with the study design (e.g., observational, qualitative, or case report).

RESULTS

The search identified 10 manuscripts: 2 observational quantitative studies (total n with PD = 545), 1 qualitative study (n with PD = 20), and 7 case reports (n = 7). The observational studies suggested that PVA is less common than other neuropsychiatric disturbances, but heterogeneous methods and quality concerns prevented further conclusions. In the case reports, all patients were male, and most were early onset. In 6 of the reports, PVA occurred in the context of bilateral subthalamic nucleus deep brain stimulation.

CONCLUSIONS

PVA, while relatively rare in PD, can be a significant management issue that is associated with select premorbid characteristics and antiparkinsonian motor treatments. As PVA may be under-reported, further understanding of its frequency, causes, risk factors, and outcomes would benefit from its systematic assessment, ideally using self-report and informant-based questionnaires.

Developmental care pathway for hospitalised infants with CHD: on behalf of the Cardiac Newborn Neuroprotective Network, a Special Interest Group of the Cardiac Neurodevelopmental Outcome Collaborative

Infants and children born with CHD are at significant risk for neurodevelopmental delays and abnormalities. Individualised developmental care is widely recognised as best practice to support early neurodevelopment for medically fragile infants born premature or requiring surgical intervention after birth. However, wide variability in clinical practice is consistently demonstrated in units caring for infants with CHD. The Cardiac Newborn Neuroprotective Network, a Special Interest Group of the Cardiac Neurodevelopmental Outcome Collaborative, formed a working group of experts to create an evidence-based developmental care pathway to guide clinical practice in hospital settings caring for infants with CHD. The clinical pathway, "Developmental Care Pathway for Hospitalized Infants with Congenital Heart Disease," includes recommendations for standardised developmental assessment, parent mental health screening, and the implementation of a daily developmental care bundle, which incorporates individualised assessments and interventions tailored to meet the needs of this unique infant population and their families. Hospitals caring for infants with CHD are encouraged to adopt this developmental care pathway and track metrics and outcomes using a quality improvement framework.

Post-Traumatic Stress Disorder and Risk of Degenerative Synucleinopathies: Systematic Review and Meta-Analysis

OBJECTIVE

A systematic review was conducted to answer whether adult-onset post-traumatic stress disorder (PTSD) is associated with increased risk of Parkinson's disease (PD) and related synucleinopathies.

DESIGN

A systematic search of Medline (Ovid), Embase (Elsevier), PsycInfo (Ovid), Cochrane Library (Wiley), and Web of Science (Clarivate) was performed using MeSH headings and equivalent terms for PTSD, PD, DLB, and related disorders.

SETTING

No restrictions.

PARTICIPANTS

Eligible articles were published in peer-reviewed journals, sampled adult human populations, and treated PTSD and degenerative synucleinopathies as exposures and outcomes, respectively.

MEASUREMENTS

Extracted data included diagnostic methods, sample characteristics, matching procedures, covariates, and effect estimates. Bias assessment was performed with the Newcastle-Ottawa scale. Hazard ratios were pooled using the random effects model, and the Hartung-Knapp adjustment was applied due to the small number of studies.

RESULTS

A total of six articles comprising seven unique samples (total n = 1,747,378) met eligibility criteria. The risk of PD was reported in three retrospective cohort studies and one case-control study. Risk of DLB was reported in one retrospective cohort, one case-control, and one prospective cohort study. No studies addressed potential relationships with multiple system atrophy or pure autonomic failure. Meta-analysis of hazard ratios from four retrospective cohort studies supported the hypothesis that incident PTSD was associated with PD and DLB risk (pooled HR 1.88, 95% C.I. 1.08-3.24; p = 0.035).

CONCLUSIONS

The sparse literature to-date supports further investigations on the association of mid- to late-life PTSD with Parkinson's and related neurodegenerative disorders.

Neuroimaging Correlates of Post-Traumatic Stress Disorder in Traumatic Brain Injury: A Systematic Review of the Literature

Neuroimaging is widely utilized in studying traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD). The risk for PTSD is greater after TBI than non-TBI trauma, and PTSD is associated with worse outcomes after TBI. Studying the neuroimaging correlates of TBI-related PTSD may provide insights into the etiology of both conditions and help identify those TBI patients most at risk of developing persistent symptoms. The objectives of this systematic review were to examine the current literature on neuroimaging in TBI-related PTSD, summarize key findings, and highlight strengths and limitations to guide future research. A PRISMA compliant literature search was conducted in PubMed (MEDLINE), PsychINFO, EMBASE, and Scopus databases prior to January 2022. The database query yielded 4486 articles, which were narrowed based on specified inclusion criteria to a final cohort of 16 studies, comprised of 854 participants with TBI. There was no consensus regarding neuroimaging correlates of TBI-related PTSD among the included articles. A small number of studies suggest that TBI-related PTSD is associated with white matter tract changes, particularly in frontotemporal regions, as well as changes in whole-brain networks of resting-state connectivity. Future studies hoping to identify reliable neuroimaging correlates of TBI-related PTSD would benefit from ensuring consistent case definition, preferably with clinician diagnosed TBI and PTSD, selection of comparable control groups, and attention to imaging timing post-injury. Prospective studies are needed and should aim to further differentiate predisposing factors from sequelae of TBI-related PTSD.

Dream Enactment Behaviors Associated With Posttraumatic Stress Disorder

The investigators aimed to draw attention to current debates surrounding the etiologies of dream enactment behaviors in patients with posttraumatic stress disorder (PTSD). The phenomenological overlap between PTSD-related nocturnal symptoms, rapid eye movement sleep behavior disorder (RBD), and trauma-associated sleep disorder (TASD) is discussed. Strategies used to diagnose and manage dream enactment behaviors, whether due to RBD or another confounding sleep disorder, are considered. Finally, the need for further research on the pathophysiological overlap and integrated treatment of PTSD, RBD, and, possibly, TASD is highlighted.

Neuroimaging correlates of syndromal depression following traumatic brain injury: A systematic review of the literature

Objective

To complete a systematic review of the literature examining neuroimaging findings unique to co-occurring syndromal depression in the setting of TBI.

Methods

A PRISMA compliant literature search was conducted in PubMed (MEDLINE), PsychINFO, EMBASE, and Scopus databases for articles published prior to April of 2022. The database query yielded 4447 unique articles. These articles were narrowed based on specific inclusion criteria (e.g., clear TBI definition, clear depression construct commenting on the syndrome of major depressive disorder, conducted empirical analyses comparing neuroimaging correlates in TBI subjects with depression versus TBI subjects without depression, controlled for the time interval between TBI occurrence and acquisition of neuroimaging).

Results

A final cohort of 10 articles resulted, comprising the findings from 423 civilians with brain injury, 129 of which developed post-TBI depression. Four articles studied mild TBI, three mild/moderate, one moderate/severe, and two all-comers, with nine articles focusing on single TBI and one including both single and recurrent injuries. Spatially convergent structural abnormalities in individuals with TBI and co-occurring syndromal depression were identified primarily in bilateral frontal regions, particularly in those with damage to the left frontal lobe and prefrontal cortices, as well as temporal regions including bilateral temporal lobes, the left superior temporal gyrus, and bilateral hippocampi. Various parietal regions and the nucleus accumbens were also implicated. EEG studies showed supporting evidence of functional changes in frontal regions.

Conclusion

Additional inquiry with attention to TBI without depression control groups, consistent TBI definitions, previous TBI, clinically diagnosed syndromal depression, imaging timing post-injury, acute prospective design, functional neuroimaging, and well-defined neuroanatomical regions of interest is crucial to extrapolating finer discrepancies between primary and TBI-related depression.

Presence of obstructive sleep apnea is associated with higher future readmissions and outpatient visits-a nationwide administrative dataset study

BACKGROUND

Hospital readmissions and outpatient visits contribute to the significant burden on healthcare systems. Obstructive sleep apnea (OSA) is a chronic medical condition that is associated with cardiovascular comorbidities and other chronic conditions. Inpatient and outpatient healthcare utilization rates in patients with OSA following hospitalization are unclear.

METHODS

This. retrospective case-control cohort study utilized a nationwide database to assess if OSA is associated with higher healthcare utilization post-hospitalization. We compared healthcare utilization among patients with OSA versus without OSA between 2009 and 2014 after matching for demographic variables, geographic location, hospital environment, reason for admission, and severity of illness during hospitalization. We measured future healthcare utilization by the number of ICU admissions, hospital admissions, emergency room visits, and outpatient visits after being discharged from the index hospitalization.

RESULTS

Two equal-sized cohorts comprised of 85,912 matched pairs were obtained. The OSA cohort demonstrated significantly higher rates of future ICU admissions, hospital admissions, emergency room visits, and outpatient visits. Matching for comorbid cardiovascular conditions continued to demonstrate higher healthcare utilization in the OSA group. Short-term outcomes during the index hospitalization were relatively similar between groups.

CONCLUSIONS

This retrospective database study demonstrated that OSA may be an independent marker of higher future healthcare utilization. On the other hand, the length of stay during the index hospitalization was not elevated. Prospective studies are needed to confirm these findings and investigate the impact of directing additional resources to inpatients with OSA.

Cefiderocol for the Treatment of Adult and Pediatric Patients With Cystic Fibrosis and Achromobacter xylosoxidans Infections

Treatment options for Achromobacter xylosoxidans are limited. Eight cystic fibrosis patients with A. xylosoxidans were treated with 12 cefiderocol courses. Pretreatment in vitro resistance was seen in 3 of 8 cases. Clinical response occurred after 11 of 12 treatment courses. However, microbiologic relapse was observed after 11 of 12 treatment courses, notably without emergence of resistance.

Neuroimaging Correlates of Syndromal Anxiety Following Traumatic Brain Injury: A Systematic Review of the Literature

BACKGROUND

Traumatic brain injury (TBI) can precipitate new-onset psychiatric symptoms or worsen existing psychiatric conditions. To elucidate specific mechanisms for this interaction, neuroimaging is often used to study both psychiatric conditions and TBI. This systematic review aims to synthesize the existing literature of neuroimaging findings among patients with anxiety after TBI.

METHODS

We conducted a Preferred Reporting Items for Systematic Review and Meta-Analyses-compliant literature search via PubMed (MEDLINE), PsychINFO, EMBASE, and Scopus databases before May, 2019. We included studies that clearly defined TBI, measured syndromic anxiety as a primary outcome, and statistically analyzed the relationship between neuroimaging findings and anxiety symptoms.

RESULTS

A total of 5982 articles were retrieved from the systematic search, of which 65 studied anxiety and 13 met eligibility criteria. These studies were published between 2004 and 2017, collectively analyzing 764 participants comprised of 470 patients with TBI and 294 non-TBI controls. Imaging modalities used included magnetic resonance imaging, functional magnetic resonance imaging, diffusion tensor imaging, electroencephalogram, magnetic resonance spectrometry, and magnetoencephalography. Eight of 13 studies presented at least one significant finding and together reflect a complex set of changes that lead to anxiety in the setting of TBI. The left cingulate gyrus in particular was found to be significant in 2 studies using different imaging modalities. Two studies also revealed perturbances in functional connectivity within the default mode network.

CONCLUSIONS

This is the first systemic review of neuroimaging changes associated with anxiety after TBI, which implicated multiple brain structures and circuits, such as the default mode network. Future research with consistent, rigorous measurements of TBI and syndromic anxiety, as well as attention to control groups, previous TBIs, and time interval between TBI and neuroimaging, are warranted. By understanding neuroimaging correlates of psychiatric symptoms, this work could inform future post-TBI screening and surveillance, preventative efforts, and early interventions to improve neuropsychiatric outcomes.

Clinical Correlates of Dream Enactment Behaviors in Previously Deployed OEF/OIF/OND Veterans: An Exploratory Analysis

OBJECTIVE

Veterans with posttraumatic stress disorder (PTSD) frequently report dream enactment behavior (DEB). Although DEBs are associated with PTSD symptoms, their relationship with other sleep disorders, including REM behavior disorder, warrants reexamination of their clinical correlates.

METHODS

The investigators used a cross-sectional, exploratory analysis to compare demographic and clinical characteristics of veterans endorsing regularly occurring DEB compared with those endorsing no or infrequent DEB. The participants comprised a convenience sample of servicemembers who were previously deployed to Operation Enduring Freedom/Operation Iraqi Freedom/Operation New Dawn (OEF/OIF/OND) and enrolled in an ongoing cohort study.

RESULTS

Of the 78 eligible participants, 19 (24.4%) endorsed DEBs occurring at least once per week in the past month. Compared with participants who reported no or infrequent DEBs, participants with regularly occurring DEBs had poorer sleep quality, greater PTSD severity, a higher number of reported mild traumatic brain injuries (mTBI) with loss of consciousness, and a higher likelihood of being diagnosed with sleep disorders. After adjustment for global sleep quality, a significant association persisted between DEBs and the number of mTBI with loss of consciousness but not between DEBs and the severity of PTSD symptoms.

CONCLUSIONS

These results suggest that mTBI may disrupt neural circuits regulating sleep among OIF/OEF/OND veterans. Prospective, polysomnographic assessment of muscle tone and behavioral events during REM sleep is needed to characterize the physiology of DEBs in this population.

Neurodevelopmental Outcomes Among Children With Congenital Heart Disease: At-Risk Populations and Modifiable Risk Factors

As survivable outcomes among patients with complex congenital heart disease (cCHD) have continued to improve over the last several decades, more attention is being dedicated to interventions that impact not just survival but quality of life among patients with cCHD. In particular, patients with cCHD are at risk for impaired neurodevelopmental outcomes. In this review summarizing select presentations given at the 14th Annual Pediatric Cardiac Intensive Care Society's Annual Meeting in 2019, we discuss the neurodevelopmental phenotype of patients with cCHD, patients at greatest risk of impaired development, and three specific modifiable risk factors impacting development.

Factor Analysis and Predictive Validity of Microcomputer-Based Tests ,

11 tests were selected from two microcomputer-based performance test batteries because previously these tests exhibited rapid stability (<10 min. of practice) and high retest reliability efficiencies (r>0.707 for each 3 min. of testing). The battery was administered three times to each of 108 college students (48 men and 60 women) and a factor analysis was performed. Two of the three identified factors appear to be related to information processing (“encoding” and “throughput/ decoding”), and the third named an “output/speed” factor. The spatial, memory, and verbal tests loaded on the “encoding” factor and included Grammatical Reasoning, Pattern Comparison, Continuous Recall, and Matrix Rotation. The “throughput/ decoding” tests included perceptual/numerical tests like Math Processing, Code Substitution, and Pattern Comparison. The output speed factor was identified by Tapping and Reaction Time tests. The Wonderlic Personnel Test was group administered before the first and after the last administration of the performance tests. The multiple Rs in the total sample between combined Wonderlic as a criterion and less than 5 min. of microcomputer testing on Grammatical Reasoning and Math Processing as predictors ranged between 0.41 and 0.52 on the three test administrations. Based on these results, the authors recommend a core battery which, if time permits, would consist of two tests from each factor. Such a battery is now known to permit stable, reliable, and efficient assessment.

Acquired von Willebrand Syndrome: An Under-Recognized Cause of Major Bleeding in the Cardiac Intensive Care Unit

BACKGROUND

Acquired von Willebrand syndrome (AvWS) in the setting of congenital heart disease is an under-recognized cause of bleeding in the pediatric cardiac critical care unit.

METHODS

Fourteen patients diagnosed with AvWS admitted to the cardiac intensive care unit at the Children's National Health System between December 2009 and September 2015 were identified with subsequent chart review and case analysis.

RESULTS

Of the 14 patients included in this study, 4 patients were on ventricular-assist devices, 6 patients were on extracorporeal membrane oxygenation, and 4 were patients with congenital heart disease not receiving any mechanical circulatory support. All patients identified manifested persistent severe bleeding, despite appropriate management of anticoagulation and blood product administration based on the established protocols. Detailed hemostatic testing including quantitative von Willebrand factor (vWF) multimer analysis revealed decreased high-molecular-weight multimers (HMWMs) and absent ultra-HMWM, consistent with AvWS in all patients. Eight patients received treatment with vWF concentrate, one patient with desmopressin, and five recovered without specific treatment. Bleeding ceased in all but one patient.

CONCLUSIONS

Acquired von Willebrand syndrome is an uncommon but important cause of bleeding in pediatric patients with cardiac disease. A high index of clinical suspicion with knowledge of the characteristic clinical scenario in addition to low levels of vWF multimers is required to manage and diagnose AvWS. Although the optimal management of AvWS in this patient population is unclear, vWF concentrates are available and appear to be efficacious for controlling life-threatening bleeding.

Hybrid Exclusion of HeartMate ІІ Left Ventricular Assist Device After Bridge to Recovery

We present a hybrid technique of left ventricular assist device exclusion after bridge to recovery in a pediatric patient, using percutaneous occlusion of the outflow graft and surgical excision of driveline. This technique has the advantage of avoiding chest reentry and cardiopulmonary bypass.

The effect of renovation of long-term temperate grassland on N2O emissions and N leaching from contrasting soils

Renovation of long-term grassland is associated with a peak in soil organic N mineralisation which, coupled with diminished plant N uptake can lead to large gaseous and leaching N losses. This study reports on the effect of ploughing and subsequent N fertilisation on the N2O emissions and DON/NO3(-) leaching, and evaluates the impact of ploughing technique on the magnitude and profile of N losses. This study was carried out on isolated grassland lysimeters of three Irish soils representing contrasting drainage properties (well-drained Clonakilty, moderately-drained Elton and poorly-drained Rathangan). Lysimeters were manually ploughed simulating conventional (CT) and minimum tillage (MT) as two treatments. Renovation of grassland increased N2O flux to a maximum of 0.9kgN2O-Nha(-1) from poorly-drained soil over four days after treatment. Although there was no difference between CT and MT in the post-ploughing period, the treatment influenced subsequent N2O after fertiliser applications. Fertilisation remained the major driver of N losses therefore reducing fertilisation rate post-planting to account for N mineralised through grassland renovation could reduce the losses in medium to longer term. Leaching was a significant loss pathway, with the cumulative drainage volume and N leached highly influenced by soil type. Overall, the total N losses (N2O+N leached) were lowest from poorly and moderately draining soil and highest for the well draining soil, reflecting the dominance of leaching on total N losses and the paramount importance of soil properties.

Perceptions of Bedside Cardiac Critical Care Registered Nurses on 24 Hour Attending Intensivist Coverage

OBJECTIVE

To elicit the perceptions of bedside critical care nurses toward continual in-house attending coverage and its effect on patient safety, communication, and nursing education.

DESIGN

A 5-point Likert-type questionnaire was designed to evaluate the perception of bedside nurses in the pediatric cardiac intensive care unit (PCICU) toward the presence of a 24 hour in-house attending physician.

SETTING

Single tertiary referral PCICU in Washington, DC SUBJECTS: The 46 PCICU nurses who participated in the study were separated into two groups based on exposure to the recent implementation of continual in-house attending coverage at our institution. Group one consisted of 14 nurses with only exposure to the new 24/7 in-house coverage while group two encompassed 32 nurses who had experienced both the new and old system (off-site on-demand attending physician).

MEASUREMENTS AND MAIN RESULTS

Surveys demonstrated that both groups found that the new system has a positive impact on nursing education (median score of 5) as well as a positive impact on the communication between multidisciplinary teams and between care team and families (median score of 5). Nurses who experienced only the new system scored one point lower (median score of 4) regarding the effect of this staffing model on patient outcomes than nurses who had experienced both systems (median score of 5, P = .016). Between 83% and 98% of all 46 nurses who participated indicated they agree or strongly agree with each of the questions regarding the benefit of 24 hour in-house attending coverage.

CONCLUSION

Our study suggests that regardless of differences in experience, pediatric cardiac nurses believe the presence of an on-site intensivist to be beneficial to both nursing and patients.

Acquired von Willebrand syndrome in a child following Berlin Heart EXCOR Pediatric Ventricular Assist Device implantation: case report and concise literature review

The development of acquired von Willebrand syndrome (AVWS) after placement of a pulsatile-flow left ventricular assist device (LVAD) is rare and only recently recognized. We report the case of a young infant who was diagnosed with ventricular assist device (VAD)-related AVWS following implantation of a Berlin Heart EXCOR Pediatric Ventricular Assist Device (Berlin Heart Inc., The Woodlands, Texas, USA) for treatment of severe heart failure. Despite significant bleeding, the patient was successfully managed with von Willebrand factor-containing concentrate until VAD explantation led to definitive resolution of the AVWS. This case demonstrates that the possibility of this diagnosis should be considered in pediatric patients when extensive, nonsurgical bleeding is encountered after pulsatile-flow VAD implantation.

The Effect of the Lipid Layer on Tear Film Behaviour

This paper investigates the effect of surfactants during tear film deposition and subsequent thinning. The surfactants occur naturally on the surface of the tear film in the form of a lipid layer. A lubrication model is developed that describes lipid spreading and film height evolution. It is shown that lipids may play an important role in drawing the tear film up the cornea during the opening phase of the blink. Further, nonuniform distributions of lipids may lead to a rapid thinning of the tear film behind the advancing lipid front (shock). Experiments using a fluorescein dye technique and using a tearscope were undertaken in order to visualise the motion of the lipid layer and any associated shocks immediately after a blink. It is found that the lipid layer continues to spread upwards on the cornea after the opening phase of the blink, in agreement with the model. Using the experimental data, lipid particles were tracked in order to determine the surface velocity and these results are compared to the model predictions.

The potential of ecotoxicoproteomics in environmental monitoring: biomarker profiling in mussel plasma using ProteinChip array technology

New global technologies, allowing simultaneous analysis of thousands of genes, proteins, and metabolites (so-called "omics" technologies), are being adopted rapidly by industry, academia, and regulatory agencies. This study evaluated the potential of proteomics in ecotoxicological research (i.e., ecotoxicoproteomics). Filter-feeding mussels (Mytilus edulis) were exposed continuously for 3 wk to oil, or oil spiked with alkylphenols and extra polycyclic aromatic hydrocarbons. The influence of chronic exposure on mussel plasma protein expression was investigated utilizing ProteinChip array technology in combination with surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI TOF MS). Results indicated that exposure to spiked oil had a more significant effect on protein expression in mussels than oil alone. In total, 83 mass peaks (intact or modified proteins/peptides) were significantly altered by spiked oil, while 49 were altered by oil. In exposed organisms, the majority of peaks were upregulated compared to controls (i.e., 69% in oil and 71% in spiked oil). Some peaks (32 in total) were affected by both treatments; however, the degree of response was higher in the spiked oil group for 25 of the 32 commonly affected features. Additionally, certain peaks revealed exposure- or gender-specific responses. Multivariate analysis with regression tree-based methods detected protein patterns associated with exposure that correctly classified masked samples with 90-95% accuracy. Similarly, 92% of females and 85% of males were correctly classified (independent of exposure). Results indicate that proteomics have the potential to make a valuable contribution to environmental monitoring and risk assessment.

Dynamics of tear film deposition and draining

This paper investigates the deposition of the tear film on the cornea of the human eye. The tear film is laid down by the motion of the upper eyelid and then subsequently flows and thins. Of particular interest is the stability of the tear layer and the development of dry patches on the cornea. While there has been significant research on the behaviour of tear films between blinks, this paper focuses on understanding the mechanisms which control the shape and thickness of the deposited film and how this affects the subsequent film behaviour. Numerical and analytical methods are applied to a lubrication model which includes the effects of surface tension, viscosity, gravity and evaporation. The model reveals the importance of the eyelid velocity, motion of the surface lipid layer and the storage of tear film between blinks.

Transepidermal Water Loss Dynamics of Human Vulvar and Thigh Skin

Refinement in procedures to assess skin surface water loss (SSWL) dynamics of the vulvar skin on a large sample of subjects (60) is described and compared to another semi-occluded skin site, the inner thigh. Vulvar SSWL significantly decreased over a 30-min period from 46.2 +/- 2.6 (SE) to 24.7 +/- 1.6 g m(-2) h (p < 0.001). The inner thigh, another semi-occluded region, showed no similar pattern for SSWL (6.2 +/- 0.3 to 6.6 +/- 0.5 g m(-2) h), and the values were significantly less than those for vulvar skin. There was no significant effect of age, body mass index or atopic status on vulvar SSWL.

Temperature-dependent physiological response of Carcinus maenas exposed to copper

The effect of temperature on the heart rate (fH) of Carcinus maenas exposed to a sublethal nominal concentration (0.5 mg l(-1)) of copper is reported. Adult, intermoult males (4 cm carapace width) were collected from Stavanger Fjord (Norway) in August (seawater TEMPERATURE=17 degrees C) and maintained in the laboratory (fed ad libitum) at 5, 15 and 25 degrees C for 7 days. Following this holding period, crabs were exposed to waterborne copper at the same temperature. After 3 days of exposure, individual fH was measured using the non-invasive Computer Aided Physiological MONitoring system (CAPMON) method. Copper-exposed individuals demonstrated significantly increased fH compared with controls at 5 and 25 degrees C (P<0.01). It is inferred that physiological function in C. maenas may be more vulnerable to copper contamination at seasonal temperature extremes (5 and 25 degrees C) than at the 'standard' test temperature (15 degrees C). Additionally, cardiac arrest observed at 5 degrees C is interpreted as a physiological response to limit copper uptake while the erratic fH in the 25 degrees C group reflected enhanced copper toxicity.

Differential sensitivity of three marine invertebrates to copper assessed using multiple biomarkers

Understanding how biomarkers relate to each other on exposure to particular contaminants in different species is key to their widespread application in environmental management. However, few studies have systematically used multiple biomarkers in more than a single species to determine the variability of sublethal effects of a particular contaminant. In this study, three marine invertebrates, the shore crab Carcinus maenas, the common limpet Patella vulgata and the blue mussel Mytilus edulis, were exposed over 7 days in the laboratory to environmentally realistic concentrations of the priority pollutant copper. A combination of molecular, cellular and physiological biomarkers was measured in each organism to detect the toxic effects of copper. Biomarkers included lysosomal stability (neutral red retention), neurotoxicity (acetylcholinesterase activity), metabolic impairment (total haemolymph protein), physiological status (heart rate) and induction of protective metallothionein proteins. P. vulgata was the most sensitive to copper with significant effects measured in all biomarkers at concentrations of 6.1 microg Cu l(-1). In C. maenas, cellular and neurotoxic endpoints were affected significantly only at 68.1 microg Cu l(-1). Exposure to copper also induced metallothionein production in crabs. Over a 7-day exposure period, M. edulis was the most tolerant species to copper with significant effects being observed at the cellular level only at 68.1 microg Cu l(-1) . In all three species, cellular and neurotoxic pathways were more sensitive to disruption than physiological processes (protein and heart rate). Results illustrate how a suite of biomarkers applied to different sentinel species can provide a 'diagnosis of stress', whereby, effects at the molecular level can be used to interpret the level of physiological impairment of the organism.

Two novel paradigms for the simultaneous assessment of conditioned taste aversion and food intake effects of anorexic agents

The conditioned taste aversion (CTA) is routinely used to assess the aversive consequences of anorexic agents, including potential pharmacological therapies for obesity. In a typical CTA paradigm, rats briefly sampling a novel tastant (e.g., saccharin) are acutely administered with toxin (e.g., lithium chloride, LiCl). After as few as one taste-toxin pairing, rats will reliably avoid the novel tastant. This paradigm is frequently used for the assessment of possible aversive consequences of drugs that are candidates for pharmacological therapies. The degree to which the drug supports development of a CTA is interpreted as an index of its aversive properties. Difficulties with previous work include the inability to assess affects on food intake and CTA simultaneously, particularly during chronic drug administration. We report here two novel CTA paradigms for the assessment of appetitive and aversive consequences of anorexic agents, simultaneously. In the first experiment, animals receive an intraoral infusion of a novel and highly palatable tastant immediately prior to administration of increasing doses of LiCl. In the second experiment, rats were implanted intraperitoneally with osmotic minipumps that chronically delivered a low dose of LiCl for 7 days. LiCl did not affect short or long term food intake in either experiment. However, LiCl did support the development of a CTA in both paradigms. These results suggest that both the appetitive and aversive consequences of anorexic agents can be assessed simultaneously during either acute or chronic drug administration.

Biomarker responses and PAH uptake in Mya truncata following exposure to oil-contaminated sediment in an Arctic fjord (Svalbard)

Expanding industrial activity (notably oil and gas exploration) in the Arctic requires assessment of the potential impact of chemicals on marine organisms living in seawater at low temperature. The bivalve Mya truncata is common in Svalbard fjord (Norway) where it experiences low temperature throughout the year. To measure the impact of polycyclic aromatic hydrocarbons (PAH) on M. truncata, the responses of three biomarkers [total oxyradical scavenging capacity-assay (TOSC), plasma membrane stability of haemocytes and respiration rates] were investigated from bivalves exposed to sediment contaminated with a PAH mixture (crude oil). After two weeks of exposure to the contaminated sediment, TOSC showed no change. The high TOSC value (4010+/-1339 unit mg(-1) protein) of Mya truncata (control group) is thought to protect biomolecules with a low turnover rate efficiently in a low food availability environment. In the exposed bivalves, the haemocyte cellular membranes were significantly destabilised compared with controls (P<0.05). Respiration rate of control and PAH-exposed individuals (0.055+/-0.020 mg O(2) dw(-1) h(-1)) was similar and relatively low as is typical for polar bivalves, reflecting a strategy to minimise energy expenditure to cope with 9 months of starvation. Bioaccumulation of PAH by M. truncata was also low, due probably to a combination of low metabolic rate and reduced solubility of the oil compounds at low temperature. Data indicated an uptake of mainly low molecular weight compounds (two and three ring molecules). A good correlation of logBAF(lipid) (bioaccumulation factor) and logK(ow) (octanol/water partitioning coefficient) was shown (r(2)=0.87). Tissue sensitivity and/or functional differences (digestive gland vs. haemocytes), PAH uptake route (dietary vs. gills), the low metabolic rate of M. truncata and the low environmental temperature (reducing the bioavailability of PAH) are factors that help explain these findings.

Assessment of the aversive consequences of acute and chronic administration of the melanocortin agonist, MTII

BACKGROUND

The synthetic melanocortin (MC) agonist, melanotan-II (MTII), reduces food intake and body weight for hours to days after administration. One early report on the effect of MTII suggested that part of its anorexic action may be mediated by aversive consequences. In that experiment, MTII was found to support a mild conditioned taste aversion (CTA).

OBJECTIVE

The present experiments replicate and extend those findings in two additional CTA paradigms to further characterize the aversive effects of MTII in rats.

METHODS

Experiment 1 simultaneously assessed the ability of MTII to support CTA and reduce food intake, using a small oral infusion of a novel taste as the conditioned stimulus. Experiment 2 assessed the aversive consequences of chronic MTII administration. To accomplish this, we paired implantation of lithium chloride (LiCl)-, MTII- or saline-containing osmotic minipumps with a constantly available novel flavor. After 7 days, rats received a choice test between the minipump-paired flavor and a previously available neutral flavor.

RESULTS

Rats with saline minipumps exhibited no preference for either flavor. By contrast, rats in both the LiCl and MTII minipump groups significantly preferred the neutral flavor, indicating the development of a CTA. Additionally, CTA produced by administration of MTII was found to be more resistant to extinction than that produced by LiCl.

CONCLUSIONS

The reduction in food intake caused by MTII is accompanied by aversive consequences regardless of route of administration. These results present difficulties for the development of MCs-based therapies for obesity.

A copepod life-cycle test and growth model for interpreting the effects of lindane

A full life-cycle test was performed to measure the effects of lindane (3.2-3,200 microg l(-1)) on the survival, development and reproduction of the freshwater copepod Bryocamptus zschokkei. This copepod survived at relatively high concentrations of lindane compared with other freshwater crustaceans with a 10 day LC50 of 241 microg l(-1) (95% CL of 141-440). 'Equiproportional development', which assumes that each moult stage represents a specific proportion of the total development time, and is not affected by processes that influence metabolism such as temperature and food quality, was used to determine the mode of action of lindane on development in B. zschokkei. Development to adult was significantly longer at 100 microg l(-1) lindane compared with the controls, however, development remained equiproportional regardless of lindane exposure. Increased development times, therefore, are not due to a direct effect of lindane on the moulting process but are due probably to reduced food intake or increased metabolism through the stress imposed by toxicant exposure. Although the survival data suggest that B. zschokkei is relatively tolerant of lindane exposure, reproduction was affected at low lindane concentrations. At 32 microg l(-1) lindane, significantly fewer eggs and viable offspring were produced per female compared with the solvent control. At very low lindane concentrations (3.2 and 10 microg l(-1)), there was a significant increase in the numbers of offspring produced per female compared with the controls and this is interpreted as a hormesis effect. In conclusion, a full life-cycle test demonstrated B. zschokkei is relatively sensitive to lindane compared with other freshwater crustaceans. Incorporating a copepod growth model (equiproportional development) into the life-cycle test design, provided information on the dominant mode of action of the toxicant.

Heart rate, respiration and total oxyradical scavenging capacity of the Arctic spider crab, Hyas araneus, following exposure to polycyclic aromatic compounds via sediment and injection

Increasing industrial activity in the European Arctic has raised concerns of the potential anthropogenic impact of chemicals on this polar marine ecosystem. For the past 20 years or so, biomarkers have been developed to provide early-warning signals of detrimental impacts of chemicals on the marine ecosystem, however, most biomarker methods have been established for organisms living in temperate rather than polar waters. Little is known about biomarker responses in organisms living within the temperature range of -1.88 to +5 degrees C. In this study, established biomarkers from temperate studies were tested on the Arctic spider crab Hyas araneus to validate their use in polar ecosystems. H. araneus is common in Svalbard fjord (Norway), although it is a temperate water species occurring from northern Spain to Svalbard at depths from 10 to 1200 m. In this paper, the effects of oil were investigated at 2 degrees C via two routes: (i) injection and (ii) contaminated sediment. After 2 weeks of exposure, heart rate, oxygen consumption and total oxyradical scavenging capacity (TOSC) were measured in the same individuals. In both methods of contaminant exposure, heart rate showed a significant increase compared with the control (P < 0.0001, n = 7); mean heart rate values (+/- S.D.) of H. araneus were 49.06 (+/- 13.72), 57.56 (+/- 7.28) and 63.30 (+/- 6.57) beats per minute in control, injected and sediment-treated groups, respectively. Respiration of H. araneus was not affected significantly by either oil treatment (P > 0.05), but two individuals (n = 8) showed a marked increase in oxygen uptake in the sediment-exposed group. The basal oxygen consumption of control H. araneus was lower (0.025 mg O(2) g wet wt.(-1) h(-1)) than reported for H. araneus living in temperate water. Although TOSC of H. araneus was not affected significantly by either exposure treatment (P > 0.05) the mean TOSC value in the sediment-exposed group was lower than the control, indicating some saturation of the oxyradical scavenging system. Results indicate that although low temperature appears to be the main factor reducing the bioavailability of polycyclic-aromatic hydrocarbons, the relatively low metabolic rate of Arctic H. araneus is also implicated in decreased uptake and metabolism of oil compounds into reactive oxygen species (ROS).

Total oxyradical scavenging capacity and cell membrane stability of haemocytes of the Arctic scallop, Chlamys islandicus, following benzo(a)pyrene exposure

Industrial activities, notably oil and gas industries, are expanding in the Arctic. Most of the biomarkers were developed using temperate organisms living at temperatures above 10 degrees C. Little is known about the biomarker responses of organisms living between -1.88 and 5 degrees C. Therefore, assessment of the toxicity of chemicals to cold-water adapted species is required. In this study, the Arctic scallop, Chlamys islandicus, was selected as a key species for bio-monitoring because of wide distribution in Arctic waters and its commercial value. Test animals, stored in seawater at 2 degrees C, were injected with benzo(a)pyrene (diluted in cod liver oil 5 mg ml(-1)) in the adductor muscle every 24 h for four days giving a final dose of 0, 74 and 90.6 mg kg(-1) wet weight for control, low and high dose, respectively. The biomarkers used were total oxyradical scavenging capacity (TOSC) in the digestive gland and cell membrane stability of haemocytes. TOSC values were significantly reduced (ca. 30%) in exposed groups (P < 0.05), indicating a depletion in oxyradical molecular scavengers. The antioxidant defences appeared to be overwhelmed by the reactive oxygen species as the plasma membranes of haemocytes were destabilised (P < 0.05) probably due to lipid peroxidation. These data indicate that reactive oxygen species (ROS) were produced by Arctic scallops via the metabolisation of benzo(a)pyrene at 2 degrees C.

Trace metal uptake by the Chinese mitten crab Eriocheir sinensis: the role of osmoregulation

Changes in salinity affect the bioavailability and consequent uptake of trace metals by euryhaline invertebrates. In many cases, salinity-related effects on metal uptake can be explained by changes in chemical speciation but salinity may also influence uptake indirectly through its action on osmoregulatory mechanisms. Specifically, it can be hypothesised that trace metal uptake may be reduced at salinities approaching the isosmotic point of a species because, at this point, there is reduced activity of ionic exchange pumps. The present study tested this hypothesis using the Chinese mitten crab, Eriocheir sinensis, a hyper-hypoosmoregulator with an isosmotic point around 33 per thousand. Crabs were exposed to radio-labelled cadmium and zinc at 23, 33 and 43 per thousand for 4 days. To eradicate speciation effects, crabs were exposed to the same concentration of the radio-labelled free metal ion (estimated using MineQL computer software) at each salinity. Haemolymph samples were taken daily and radio-labelled metal concentrations were estimated from radioactivity counts and used to provide relative measures of metal uptake. Neither cadmium nor zinc uptake was lowest at the isosmotic point. The uptake of cadmium increased significantly with increase in salinity, while the uptake of zinc showed no significant change with increased salinity. Thus changes in trace metal uptake rates in E. sinensis do not appear to be controlled only by changes in free metal ion concentrations. The different effects of salinity change on the uptake of cadmium and zinc (in the absence of free metal ion change) also indicate that physiological responses to osmotic change alone do not control metal uptake rates for this species.

Comparative responses to water stress in stay-green, rapid- and slow senescing genotypes of the biomass crop, Miscanthus

•  Although hybrids of the perennial rhizomatous grass Miscanthus give high yields under irrigation, their use as a biomass crop in many locations is limited by inadequate water availability. Here, the effects of reduced water availability on growth are reported for three Miscanthus genotypes with differing responses to drought. •  In a controlled environment experiment during a drought treatment M. sinensis hybrid (Sin-H6) had no detectable photosynthesis and negligible leaf conductance, whereas M. × giganteus (Gig-3) continued to photosynthesize and transpire but it shed leaf area through senescence. A M. sacchariflorus line (Sac-5) was generally intermediate in its response. Measurements on 3-y-old stands of Gig-3 and Sin-H6 in the field during a short summer drought in August 1999 confirmed the controlled environment observations. •  Stay-green characteristics in Sin-H6 appeared to rely on tight control of transpiration through lowered leaf conductance, although the highest leaf ABA concentrations were not found in this genotype. •  Stay-green genotypes, such as Sin-H6, are likely to be important for further breeding of Miscanthus because they appear to make the most effective use of available water.

Magnetic resonance imaging of denervation-induced muscle atrophy: effects of clenbuterol in the rat

We show that magnetic resonance imaging (MRI) can be used to quantify the amount of muscle in the lower legs of adult rats and to noninvasively monitor the onset and progression of denervation-induced atrophy. Muscle cross-sectional areas determined from 2D gradient-echo MR images allow longitudinal quantification of the protective effects of a beta(2)-adrenergic agonist clenbuterol. We also show that the estimation of clenbuterol's efficacy is improved by computation of the muscle volume. Rapid animal throughput and the ability to accurately estimate efficacy make MRI an attractive technology for studying skeletal muscle atrophy and hypertrophy, allowing the evaluation of potential therapies in longitudinal studies.

Effects of a tartar control whitening dentifrice on tooth shade in a population with long-standing natural stain

Changing and whitening tooth color in people with long-standing tooth stain without excessive hard tissue abrasion may represent one of the more difficult challenges for whitening dentifrices. An eight-week clinical trial was conducted to evaluate change in tooth color by a silica-based, enamel-safe tartar control whitening dentifrice compared to a marketed baking soda dentifrice control. First, a screening exercise was conducted to identify individuals with long-standing extrinsic dental stain. This exercise targeted adults who reported "stained teeth" and coffee/tea drinking or smoking, but who had no recent history of dental prophylaxis. Targeted subjects were examined for stain (Lobene Index) and tooth shade/color (Vita). A total of 291 adults having extrinsic stain and discolored teeth were enrolled in the study. Subjects were randomized to one of the two treatment groups, and all dentifrice use was unsupervised. Tooth color was measured at 4 and 8 weeks from shade values collected from the 8 incisors, and averages were determined from a linear ordering of the shade guide. A total of 278 evaluable subjects completed the 8-week study. Overall, the tartar control whitening dentifrice group experienced an improvement in color, differing statistically from baseline (p < 0.001) and from the marketed control (p < 0.05). Safety profiles for the two dentifrices were generally similar. Among patients with long-standing extrinsic stain, use of the tartar control whitening dentifrice resulted in superior overall tooth shade and reduced maximum or worst color compared to the marketed baking soda dentifrice control.

Impairment of mysid (Neomysis integer) swimming ability: an environmentally realistic assessment of the impact of cadmium exposure

Neomysis integer (Crustacea: Mysidacea), a euryhaline member of the hyperbenthos of the upper reaches of European estuaries, has been identified as a suitable animal for assessing the impacts of chemical pollutants on these estuarine regions. In this study, the effect of a 7 day pre-exposure to environmentally relevant concentrations of cadmium (0.5 and 1.0 microg l(-1)) on the swimming behaviour of N. integer was examined using an annular flume. Cadmium speciation at two salinities (1 and 10 per thousand) that dominate these upper estuarine regions was modelled to ensure mysids were exposed to the same concentration of the toxic free-ion at each salinity. There was no significant difference in the swimming behaviour of mysids exposed to the same free-ion cadmium concentration at the two different salinities. At each salinity, exposure to 0.5 microg Cd2+ (aq) l(-1)resulted in fewer mysids moving forward into the current (normal behaviour) at free stream velocities typical of their natural habitat (e.g. 3-9 cm s(-1)) than non cadmium-exposed mysids. At these low current speeds, cadmium-exposed mysids were either able to maintain position or were swept by the current. The same general responses were recorded for mysids exposed to 1.0 microg Cd2+ (aq) l(-1)except that more mysids showed disrupted swimming ability compared with 0.5 microg Cd2+ (aq) l(-1). At higher current speeds (>12 cm s(-1)), current velocity was the dominant factor affecting mysid swimming behaviour and there was no effect of cadmium on mysids maintaining position. Exposure to cadmium also caused significant disruption of the hyperbenthic behaviour of N. integer and more cadmium-exposed individuals were in the water column than control mysids; this result was more variable at 10 per thousand than 1 per thousand. Results indicate that exposure to cadmium concentrations of 0.5 microg Cd2+(aq) l(-1)would result in displacement of N. integer from its optimum region within the estuarine environment. This conclusion would not be achieved from standard LC(50) tests (e.g. 7 day LC50 = 2.95 microg Cd2+ (aq) l(-1)), highlighting the value of behavioural disruption as a sensitive indicator of environmental chemical contamination.

Effects of salinity and chemical speciation on cadmium accumulation and toxicity to two mysid species

The estuarine environment is characterized by frequent fluctuations in salinity. Consequently, organisms used for environmental monitoring of estuaries must be euryhaline so that their laboratory responses to chemical pollutants are measured under the full range of salinity exposures experienced in the field. Neomysis integer and Praunus flexuosus are two potential candidates for use in environmental monitoring of European estuaries. The present study assesses the effects of salinity on survival, trace metal accumulation, and toxicity to these two mysid species. Neomysis integer was more euryhaline, showing 100% survival at 1 to 40@1000 compared with P. flexuosus, which showed 100% survival at salinities of 10 to 40@1000. Toxicity of the free cadmium ion to both species was unaffected by salinity, and 96-h LC50s ranged from 4.8 to 15 micrograms Cd2+/L for N. integer and from 12.3 to 16 micrograms Cd2+/L for P. flexuosus. The 7-d LC50s ranged from 1.0 to 4.2 and 4.8 to 5.3 micrograms Cd2+/L for N. integer and P. flexuosus, respectively. No effect of exposure salinity was found on cadmium body burdens of mysids exposed for 7 d to 0.5 and 1.0 microgram Cd2+/L. The results are discussed in terms of possible effects of osmoregulatory mechanisms on trace metal uptake, accumulation, and toxicity.

Efficacy and safety of 'hot' tonsillectomy

Recurrent acute tonsillitis, peritonsillar infections and quinsy (peritonsillar abscess) are common clinical conditions that present to a general practitioner. Management in general practice and in hospital is confounded by apparently conflicting treatment options in the medical literature. We have developed clear guidelines as part of an ongoing audit cycle which include performing quinsy or 'hot' tonsillectomy in selected cases, alongside conservative treatments to ensure the speedy recovery and minimal hospitalisation of all patients, with resultant cost benefits.

The relationship between trace metal contamination and stream meiofauna

The effect of chemical contaminants on freshwater meiofaunal communities is poorly understood and meiofauna rarely form part of environmental impact assessments in fresh waters. The community composition and diversity of meiofauna in streams of southwest England (Cornwall) representing a gradient in trace metal contamination were investigated. Multivariate and univariate statistical techniques were used to correlate community composition, diversity and environmental variables. Meiofaunal communities were very different at sites with high compared with low metal concentrations. Copper, either singly, or in combination with other environmental variables (aluminium, zinc or dissolved organic carbon), was the most important correlate with community composition. Not all meiofaunal species were adversely affected by metals, however, and some taxa, most notably certain cyclopoid copepods, were abundant at high metal concentrations. Moreover, sites with high metal concentrations were not significantly less diverse than sites of low metal concentrations. These data suggest that metal contamination significantly alters the composition of stream meiofaunal assemblages and highlight the importance of including meiofauna in impact studies of fresh waters.

Activation and inhibition of G protein-coupled inwardly rectifying potassium (Kir3) channels by G protein beta gamma subunits

G protein-coupled inwardly rectifying potassium (GIRK) channels can be activated or inhibited by different classes of receptors, suggesting a role for G proteins in determining signaling specificity. Because G protein betagamma subunits containing either beta1 or beta2 with multiple Ggamma subunits activate GIRK channels, we hypothesized that specificity might be imparted by beta3, beta4, or beta5 subunits. We used a transfection assay in cell lines expressing GIRK channels to examine effects of dimers containing these Gbeta subunits. Inwardly rectifying K(+) currents were increased in cells expressing beta3 or beta4, with either gamma2 or gamma11. Purified, recombinant beta3gamma2 and beta4gamma2 bound directly to glutathione-S-transferase fusion proteins containing N- or C-terminal cytoplasmic domains of GIRK1 and GIRK4, indicating that beta3 and beta4, like beta1, form dimers that bind to and activate GIRK channels. By contrast, beta5-containing dimers inhibited GIRK channel currents. This inhibitory effect was obtained with either beta5gamma2 or beta5gamma11, was observed with either GIRK1,4 or GIRK1,2 channels, and was evident in the context of either basal or agonist-induced currents, both of which were mediated by endogenous Gbetagamma subunits. In cotransfection assays, beta5gamma2 suppressed beta1gamma2-activated GIRK currents in a dose-dependent manner consistent with competitive inhibition. Moreover, we found that beta5gamma2 could bind to the same GIRK channel cytoplasmic domains as other, activating Gbetagamma subunits. Thus, beta5-containing dimers inhibit Gbetagamma-stimulated GIRK channels, perhaps by directly binding to the channels. This suggests that beta5-containing dimers could act as competitive antagonists of other Gbetagamma dimers on GIRK channels.

Mysids and trace metals: disruption of swimming as a behavioural indicator of environmental contamination

Mysids are used frequently in standard laboratory studies of acute exposure to chemical contaminants. Their value for sub-lethal measures of biological response to predict the potential effects of environmental toxicants, however, has yet to be determined. In estuaries, mysids maintain their optimum position independent of the forces of river flow and tides; therefore, any disruption of swimming behaviour will have significant implications for their survival and position maintenance. In the present study, the effects of cadmium on the swimming behaviour of the hyperbenthic estuarine mysid Neomysis integer, which occupies the heads of European estuaries, are presented. Following 7 day exposure to cadmium, swimming behaviour (ability and orientation) was disrupted at 0.5 microgram Cd(aq)2+ l-1, a significantly lower cadmium concentration than that causing mortality (7 day LC50 of 2.58 micrograms Cd(aq)2+ l-1). The results of this investigation highlight the advantages of behavioural toxicity tests for predicting the influence of pollutants and support the use of mysids for estuarine monitoring.

Stability of lysosomal and cell membranes in haemocytes of the common mussel (Mytilus edulis): effect of low temperatures

Expanding industrial activities in the Arctic require an urgent assessment of the toxicity of chemicals at low temperatures. Organisms acclimatized to low temperature exhibit specific adaptations. For example, the amount of unsaturated lipids is increased to maintain the fluidity of the cell membranes. It has been hypothesized that such temperature-induced alterations in membrane lipid composition may affect the stability of lysosomal and cell membranes in the common mussel, Mytilus edulis, an organism exposed to seasonal temperature extremes. As mussels may be exposed to petroleum compounds along industrialized coastlines, we tested the combined effects of exposure to low temperature and the petroleum compound, phenanthrene, on haemocyte membrane stability. Test animals, acclimated to either 0 or 10 degrees C, were exposed to phenanthrene (0 = control or 500 micrograms l-1) and haemocytes were examined using the neutral red retention assay (lysosomal stability) and a fluorescence assay (cell membrane stability). At 0 degree C, lysosomal and cell membranes from uncontaminated mussels were destabilized compared with 10 degrees C (P = 0.0005). No significant effects (P > 0.05) of phenanthrene were detected at either temperature. Possible mechanisms underlying membrane destabilization include a weaker physical resistance of the membrane due to a higher amount of unsaturated lipids, a potentially higher level of reactive oxygen radicals at low temperature and the higher susceptibility of unsaturated lipids to oxidative stress. More work is required to better understand the consequences of this membrane destabilization at low temperature on the susceptibility of the organism to pollutants.

The familial aggregation of the lesser variant in biological and nonbiological relatives of PDD probands: a family history study

OBJECTIVE

To determine the risk of the lesser variant (or PDD-like traits) in the biological and nonbiological second- and third-degree relatives of PDD probands using a screening questionnaire and to investigate the extent to which the risk of the lesser variant differs according to various characteristics of the proband.

METHOD

The sample consists of a series of 34 nuclear families with 2 affected PDD children (multiplex, MPX), 44 families with a single PDD child (simplex, SPX), and 14 families who adopted a PDD child. Data on characteristics of the lesser variant in 1362 biological and 337 nonbiological second- and third-degree relatives were collected from parents by telephone interview and from several maternal and paternal relatives by questionnaire.

RESULTS

All components of the lesser variant were more common in biological relatives (BR) than nonbiological relatives (NBR), confirming the familial aggregation of the traits. Proband characteristics associated with an increased risk of the lesser variant in relatives were a higher level of functioning and coming from a MPX family.

CONCLUSIONS

These findings on the familial aggregation of the lesser variant suggest that the genes for PDD also confer susceptibility to the lesser variant and that PDD may be a genetically heterogeneous disorder.

Effects of misclassification on estimates of relative risk in family history studies

Two types of misclassification that commonly occur in family-genetic studies are distinguished: 1) nondifferential misclassification, in which the probability of error as to phenotype (presence or absence of psychiatric disorder) does not depend on exposure status (being kin to a case or control proband) and 2) differential misclassification, in which it does. Nondifferential misclassification of phenotype reduces the observed relative risk towards the null value, sometimes quite dramatically. Differential misclassification can bias the observed relative risk in either direction, depending on the different values of sensitivity and specificity among relatives of cases and controls. The impact of these biases on genetic-epidemiologic studies is reviewed and discussed. In particular, the ability to detect major gene effects from the pattern of relative risks in first-, second-, and third-degree relatives can be severely compromised. Although there are some methods available to correct the effects of nondifferential misclassification, a major priority for family history studies is to minimize differential misclassification.

Comparative field water relations of three Mediterranean shrub species co-occurring at a natural CO(2) vent

Annual variations in the water relations and stomatal response of Erica arborea, Myrtus communis and Juniperus communis occurring at a natural CO(2) vent were analysed under Mediterranean field conditions. A distinct gradient of CO(2)concentration ([CO(2)]) exists between two sites near a natural CO(2)-emitting vent, with higher [CO(2)] (700 micromol mol(-1)) in the proximity of the CO(2) spring. Plants at the CO(2) spring site have been growing for generations at elevated [CO(2)]. At both sites, maximum leaf conductance was related to predawn shoot water potential. The effects of water deficits during the summer drought were severe. Leaf conductance and water potential recovered after major rainfalls in September to predrought values. Strong relationships between leaf conductance, predawn water potential, and leaf-specific hydraulic resistance are consistent with the role of stomata in regulating plant water status. Considerable between-species variation in sensitivity of water potentials and stomatal characters to elevated [CO(2)] were observed. Common to all the shrubs were a reduction in leaf conductance and an increase in water potentials in response to elevated [CO(2)]. Elevated [CO(2)] decreased the sensitivity of leaf conductance to vapour pressure deficit. Morphological characters (including stomatal density and degree of sclerophylly) showed site-dependent variations, but degree and sign of such changes varied with the species and/or the season. Measurements of discrimination against (13)C provided evidence for long-term decreases of water use efficiency in CO(2) spring plants. Analysis of C isotope composition suggested that a downward adjustment of photosynthetic capacity may have occurred under elevated [CO(2)]. Elevated [CO(2)] effects on water relations and leaf morphology persisted in the long term, but the three shrubs growing in the same environment showed species-specific responses.

Proteomic analysis of the atrophying rat soleus muscle following denervation

A proteomic analysis was performed comparing normal rat soleus muscle to denervated soleus muscle at 0.5, 1, 2, 4, 6, 8 and 10 days post denervation. Muscle mass measurements demonstrated that the times of major mass changes occurred between 2 and 4 days post denervation. Proteomic analysis of the denervated soleus muscle during the atrophy process demonstrated statistically significant (at the p < 0.01 level) changes in 73 soleus proteins, including coordinated changes in select groups of proteins. Sequence analysis of ten differentially regulated proteins identified metabolic proteins, chaperone and contractile apparatus proteins. Together these data indicate that coordinated temporally regulated changes in the proteome occur during denervation-induced soleus muscle atrophy, including changes in muscle metabolism and contractile apparatus proteins.

Ionic currents in cardiac myocytes of squid, Alloteuthis subulata

This paper provides the first study of voltage-sensitive membrane currents present in heart myocytes from cephalopods. Whole cell patch clamp recordings have revealed six different ionic currents in myocytes freshly dissociated from squid cardiac tissues (branchial and systemic hearts). Three types of outward potassium currents were identified: first, a transient outward voltage-activated A-current (IA), blocked by 4-aminopyridine, and inactivated by holding the cells at a potential of -40 mV; second, an outward, voltage-activated, delayed rectifier current with a sustained time course (IK); and third, an outward, calcium-dependent, potassium current (IK(Ca)) sensitive to Co2+ and apamin, and with the characteristic N-shaped current voltage relationship. Three inward voltage-activated currents were also identified. First, a rapidly activating and inactivating, sodium current (INa), blocked by tetrodotoxin, inactivated at holding potentials more positive than -40 mV, and abolished when external sodium was replaced by choline. Second, an L-type calcium current (ICa,L) with a sustained time course, suppressed by nifedipine or Co2+, and enhanced by substituting Ca2+ for Ba2+ in the external medium. The third inward current was also carried by calcium ions, but could be distinguished from the L-type current by differences in its voltage dependence. It also had a more transient time course, was activated at more negative potentials, and resembled the previously described low-voltage-activated, T-type calcium current.

Isoperformance and personnel decisions

Isoperformance curves are contour lines or surfaces that trace all combinations of two or more determinants that suffice to produce a specified level of performance hence the term isoperformance. When the determinants are aptitude and training time or time on the job, an isoperformance curve allows one to identify individuals who have sufficient aptitude for the work that they can be expected to reach a specified standard of performance in a specified length of time. This paper discusses isoperformance in the personnel selection and classification literature and then develops and illustrates the uses of isoperformance curves in personnel decisions. The idea of aptitude sensitivity is introduced, and the relationship between this idea and predictive validity is explained. The paper also indicates how isoperformance can be used to detail trade-offs among training time, the minimum qualifying score, attrition rate, quotas, and the specified level of criterion performance, Isoperformance finds direct application in the multiple-job assignment problem, exemplified by the choice of which recruit to send to which training school in the military services.