[Formula: see text] Cognitive disengagement syndrome in pediatric patients with long COVID: associations with mood, anxiety, and functional impairment

Children with long COVID often report symptoms that overlap with cognitive disengagement syndrome (CDS, previously sluggish cognitive tempo (SCT)), a set of behaviors distinct from attention-deficit/hyperactivity disorder (ADHD) including excessive daydreaming, mental fogginess, and slowed behavior and thinking. Those with long COVID also frequently report low mood and anxiety, which are linked to CDS. The relationships between cognitive difficulties, mood, and functional impairment have yet to be explored in pediatric long COVID. Specifically, it is unclear how much cognitive difficulties (CDS, inattention) contribute to functional impairment, when accounting for mood/anxiety symptoms in this population. Retrospective parent-reported data was collected from 34 patients with long COVID (22 females, Mage = 14.06 years, SD = 2.85, range 7-19) referred for neuropsychological consultation through a multidisciplinary Post-COVID-19 clinic. Compared to community and clinically referred samples, on average, long COVID patients showed elevated CDS symptoms, including Sluggish/sleepy (e.g., fatigue) and Low Initiation subscales (e.g., difficulty performing goal directed behaviors). Low Initiation, mood, anxiety, and inattention were associated with functional impairment. In multiple hierarchical regression models, after controlling for mood and anxiety, Low Initiation and inattention were no longer predictive of functional impairment. Instead, anxiety remained the sole predictor of functional impairment. Our results demonstrate that children with long COVID have high levels of CDS symptoms. The association between cognitive difficulties and functional impairment dissipated with the inclusion of mood and anxiety, suggesting behavioral health interventions targeting anxiety may help improve daily functioning and quality of life in pediatric long COVID patients.

An Initial Psychometric Evaluation of a Novel Upper Extremity Pediatric Stroke Hemiplegic Motor Impairment Scale

BACKGROUND

Our team designed an innovative, observation-based motor impairment measure-the Pediatric Stroke Hemiplegic Motor Impairment Scale (Pedi HEMIs). Here we present the results of a survey describing common practices in the pediatric stroke community and the initial psychometric properties of the upper extremity subscale of the Pedi HEMIs (Pedi HEMIs-UE).

METHODS

This is a cross-sectional study whereby participants completed a battery of assessments including the novel Pedi HEMIs-UE. Internal consistency was measured via Cronbach alpha (α). Intraclass correlation (ICC) was used to assess inter-rater reliability (IRR). Concurrent validity was investigated using Pearson or polychoric correlations and simple linear regressions.

RESULTS

The study sample consisted of 18 children aged 1.08 to 15 years. Two participants completed two sets of evaluations, totaling 20 data sets. Cronbach α, a measure of internal consistency, was on average 0.91 (range: 0.89 to 0.92). IRR was excellent with the six raters in almost perfect agreement (ICC = 0.91; 95% confidence interval [CI]: 0.83 to 0.96). Pearson correlation coefficient between the Pedi HEMIs-UE and logit Assisting Hand Assessment (AHA)/mini-AHA was -0.938 (95% CI: -0.979 to -0.827, P < 0.001), indicating excellent concurrent validity.

CONCLUSIONS

We found excellent feasibility, reliability, and validity of the Pedi HEMIs-UE in a convenience sample of youth with hemiparesis after stroke.

Core outcome measurement set for research and clinical practice in post-COVID-19 condition (long COVID) in children and young people: an international Delphi consensus study "PC-COS Children"

The coronavirus disease 2019 (COVID-19) pandemic substantially impacted different age groups, with children and young people not exempted. Many have experienced enduring health consequences. Presently, there is no consensus on the health outcomes to assess in children and young people with post-COVID-19 condition. Furthermore, it is unclear which measurement instruments are appropriate for use in research and clinical management of children and young people with post-COVID-19. To address these unmet needs, we conducted a consensus study, aiming to develop a core outcome set (COS) and an associated core outcome measurement set (COMS) for evaluating post-COVID-19 condition in children and young people. Our methodology comprised of two phases. In phase 1 (to create a COS), we performed an extensive literature review and categorisation of outcomes, and prioritised those outcomes in a two-round online modified Delphi process followed by a consensus meeting. In phase 2 (to create the COMS), we performed another modified Delphi consensus process to evaluate measurement instruments for previously defined core outcomes from phase 1, followed by an online consensus workshop to finalise recommendations regarding the most appropriate instruments for each core outcome. In phase 1, 214 participants from 37 countries participated, with 154 (72%) contributing to both Delphi rounds. The subsequent online consensus meeting resulted in a final COS which encompassed seven critical outcomes: fatigue; post-exertion symptoms; work/occupational and study changes; as well as functional changes, symptoms, and conditions relating to cardiovascular, neuro-cognitive, gastrointestinal and physical outcomes. In phase 2, 11 international experts were involved in a modified Delphi process, selecting measurement instruments for a subsequent online consensus workshop where 30 voting participants discussed and independently scored the selected instruments. As a result of this consensus process, four instruments met a priori consensus criteria for inclusion: PedsQL multidimensional fatigue scale for "fatigue"; PedsQL gastrointestinal symptom scales for "gastrointestinal"; PedsQL cognitive functioning scale for "neurocognitive" and EQ-5D for "physical functioning". Despite proposing outcome measurement instruments for the remaining three core outcomes ("cardiovascular", "post-exertional malaise", "work/occupational and study changes"), a consensus was not achieved. Our international, consensus-based initiative presents a robust framework for evaluating post-COVID-19 condition in children and young people in research and clinical practice via a rigorously defined COS and associated COMS. It will aid in the uniform measurement and reporting of relevant health outcomes worldwide.

International Care programs for Pediatric Post-COVID Condition (Long COVID) and the way forward

BACKGROUND

Pediatric Post-COVID-Condition (PPCC) clinics treat children despite limited scientific substantiation. By exploring real-life management of children diagnosed with PPCC, the International Post-COVID-Condition in Children Collaboration (IP4C) aimed to provide guidance for future PPCC care.

METHODS

We performed a cross-sectional international, multicenter study on used PPCC definitions; the organization of PPCC care programs and patients characteristics. We compared aggregated data from PPCC cohorts and identified priorities to improve PPCC care.

RESULTS

Ten PPCC care programs and six COVID-19 follow-up research cohorts participated. Aggregated data from 584 PPCC patients was analyzed. The most common symptoms included fatigue (71%), headache (55%), concentration difficulties (53%), and brain fog (48%). Severe limitations in daily life were reported in 31% of patients. Most PPCC care programs organized in-person visits with multidisciplinary teams. Diagnostic testing for respiratory and cardiac morbidity was most frequently performed and seldom abnormal. Treatment was often limited to physical therapy and psychological support.

CONCLUSIONS

We found substantial heterogeneity in both the diagnostics and management of PPCC, possibly explained by scarce scientific evidence and lack of standardized care. We present a list of components which future guidelines should address, and outline priorities concerning PPCC care pathways, research and international collaboration.

IMPACT

Pediatric Post-COVID Condition (PPCC) Care programs have been initiated in many countries. Children with PPCC in different countries are affected by similar symptoms, limiting many to participate in daily life. There is substantial heterogeneity in diagnostic testing. Access to specific diagnostic tests is required to identify some long-term COVID-19 sequelae. Treatments provided were limited to physical therapy and psychological support. This study emphasizes the need for evidence-based diagnostics and treatment of PPCC. The International Post-COVID Collaboration for Children (IP4C) provides guidance for guideline development and introduces a framework of priorities for PPCC care and research, to improve PPCC outcomes.

Stroke in the Developing Brain: Neurophysiologic Implications of Stroke Timing, Location, and Comorbid Factors

BACKGROUND

Pediatric stroke, which is unique in that it represents a static insult to a developing brain, often leads to long-term neurological disability. Neuroplasticity in infants and children influences neurophysiologic recovery patterns after stroke; therefore outcomes depend on several factors including the timing and location of stroke and the presence of comorbid conditions.

METHODS

In this review, we discuss the unique implications of stroke occurring in the fetal, perinatal, and childhood/adolescent time periods. First, we highlight the impact of the developmental stage of the brain at the time of insult on the motor, sensory, cognitive, speech, and behavioral domains. Next, we consider the influence of location of stroke on the presence and severity of motor and nonmotor outcomes. Finally, we discuss the impact of associated conditions on long-term outcomes and risk for stroke recurrence.

RESULTS

Hemiparesis is common after stroke at any age, although the severity of impairment differs by age group. Risk of epilepsy is elevated in all age groups compared with those without stroke. Outcomes in other domains vary by age, although several studies suggest worse cognitive outcomes when stroke occurs in early childhood compared with fetal and later childhood epochs. Conditions such as congenital heart disease, sickle cell disease, and moyamoya increase the risk of stroke and leave patients differentially vulnerable to neurodevelopmental delay, stroke recurrence, silent infarcts, and cognitive impairment.

CONCLUSIONS

A comprehensive understanding of the interplay of various factors is essential in guiding the clinical care of patients with pediatric stroke.

Exploring the Influence of Pre-Existing Conditions and Infection Factors on Pediatric Long COVID Symptoms and Quality of Life

OBJECTIVE

Pediatric post-acute sequelae of SARS-CoV-2 (PASC) or "long COVID" is a multisystemic disease with a wide range of symptoms more than 4 weeks after initial infection. This study explores the quality of life in children with long COVID and how pre-existing conditions affect symptoms and quality of life.

DESIGN

A retrospective single-center study of 97 patients was completed to analyze PedsQLTM quality of life in pediatric patients with long COVID and associations between pre-existing conditions, long COVID symptoms, and PedsQLTM scores.

RESULTS

Children with long COVID had significantly lower quality of life compared to previously published normative samples (PedsQLTM Core: p < 0.001; Fatigue: p < 0.001; Family Impact: p < 0.001). Number of long COVID symptoms, age, and pre-existing history of depression, allergies, and developmental delay affected the overall fatigue PedsQLTM scores. Pre-existing mood disorders were associated with a higher prevalence of worsening mental health symptoms (anxiety, p = 0.01; depression, p = 0.04), dizziness/lightheadedness/vertigo (p = 0.02) and change in appetite (p = 0.04).

CONCLUSIONS

Long COVID has a significant impact on the quality of life of children and their families. Children with long COVID can benefit from multidisciplinary care addressing fatigue, mental health, and family coping.

Considerations in Children and Adolescents Related to Coronavirus Disease 2019 (COVID-19)

Pediatric post-acute sequelae of SARS-CoV-2 (PASC) or "long COVID" are a complex multisystemic disease that affects children's physical, social, and mental health. PASC has a variable presentation, time course, and severity and can affect children even with mild or asymptomatic acute COVID-19 symptoms. Screening for PASC in children with a history of SARS-CoV-2 infection is important for early detection and intervention. A multifaceted treatment approach and utilization of multidisciplinary care, if available, are beneficial in managing the complexities of PASC. Lifestyle interventions, physical rehabilitation, and mental health management are important treatment approaches to improve pediatric PASC patients' quality of life.

A novel video game for remote studies of motor adaptation in children

Here we designed a motor adaptation video game that could be played remotely (at home) through a web browser. This required the child to adapt to a visuomotor rotation between their hand movement and a ball displayed in the game. The task had several novel features, specifically designed to allow the study of the developmental trajectory of adaptation across a wide range of ages. We test the concurrent validity by comparing children's performance on our remote task to the same task performed in the laboratory. All participants remained engaged and completed the task. We quantified feedforward and feedback control during this task. Feedforward control, a key measure of adaptation, was similar at home and in the laboratory. All children could successfully use feedback control to guide the ball to a target. Traditionally, motor learning studies are performed in a laboratory to obtain high quality kinematic data. However, here we demonstrate concurrent validity of kinematic behavior when conducted at home. Our online platform provides the flexibility and ease of collecting data that will enable future studies with large sample sizes, longitudinal experiments, and the study of children with rare diseases.

Characterization of Neuropsychological Outcomes in a Cohort of Pediatric Patients with Moyamoya Arteriopathy

INTRODUCTION

Moyamoya arteriopathy is a severe, progressive cerebral arteriopathy that places affected children at high risk for stroke. Moyamoya has been associated with a range of neuropsychological deficits in adults, but data on many cognitive domains remain limited in the pediatric population and little is known about the neuropsychological profile of children with syndromic moyamoya.

METHODS

This is a single-center, retrospective cohort study of children with moyamoya arteriopathy followed at our center who underwent neuropsychological testing between 2003 and 2021. Test scores were extracted from neuropsychological reports. Medical records were reviewed with attention to individual neuropsychological test results, medical comorbidities, presence of infarct(s) on neuroimaging, and history of clinical ischemic stroke.

RESULTS

Of the 83 children with moyamoya followed at our center between 2003 and 2021, 13 had completed neuropsychological testing across multiple cognitive domains. Compared to age-based normative data, children in this sample had lower scores in overall intelligence (p = 0.003), global executive functioning (p = 0.005), and overall adaptive functioning (p = 0.015). There was no significant difference in overall intelligence between children with (n = 6) versus without (n = 7) a history of clinical stroke (p = 0.368), though children with any radiographic infarct scored lower in this domain (p = 0.032).

CONCLUSION

In our cohort, children with moyamoya demonstrated impaired intelligence and executive functioning, even in the absence of clinical stroke. Neuropsychological evaluation should be considered standard of care for all children with moyamoya, even those without a history of clinical stroke.

Consensus-Based Evaluation of Outcome Measures in Pediatric Stroke Care: A Toolkit

Following a pediatric stroke, outcome measures selected for monitoring functional recovery and development vary widely. We sought to develop a toolkit of outcome measures that are currently available to clinicians, possess strong psychometric properties, and are feasible for use within clinical settings. A multidisciplinary group of clinicians and scientists from the International Pediatric Stroke Organization comprehensively reviewed the quality of measures in multiple domains described in pediatric stroke populations including global performance, motor and cognitive function, language, quality of life, and behavior and adaptive functioning. The quality of each measure was evaluated using guidelines focused on responsiveness and sensitivity, reliability, validity, feasibility, and predictive utility. A total of 48 outcome measures were included and were rated by experts based on the available evidence within the literature supporting the strengths of their psychometric properties and practical use. Only three measures were found to be validated for use in pediatric stroke: the Pediatric Stroke Outcome Measure, the Pediatric Stroke Recurrence and Recovery Questionnaire, and the Pediatric Stroke Quality of Life Measure. However, multiple additional measures were deemed to have good psychometric properties and acceptable utility for assessing pediatric stroke outcomes. Strengths and weaknesses of commonly used measures including feasibility are highlighted to guide evidence-based and practicable outcome measure selection. Improving the coherence of outcome assessment will facilitate comparison of studies and enhance research and clinical care in children with stroke. Further work is urgently needed to close the gap and validate measures across all clinically significant domains in the pediatric stroke population.

Neurological and Functional Outcomes after Pediatric Stroke

Pediatric stroke results in life-long morbidity for many patients, but the outcomes can vary depending on factors such as age of injury, or mechanism, size, and location of stroke. In this review, we summarize the current understanding of outcomes in different neurological domains (eg, motor, cognitive, language) for children with stroke of different mechanisms (ie, arterial ischemic stroke, cerebral sinus venous thrombosis, and hemorrhagic stroke), but with a focus on World Health Organization International Classification for Functioning, Disability, and Health (ICF-CY) framework for measuring health and disability for children and youth. We describe outcomes for the population as a whole and certain factors that may further refine prognostication.

Neurocognitive and Psychosocial Characteristics of Pediatric Patients With Post-Acute/Long-COVID: A Retrospective Clinical Case Series

Objective

Studies suggest a large number of patients have persistent symptoms following COVID-19 infection—a condition termed “long COVID.” Although children and parents often report cognitive difficulties after COVID, very few if any studies have been published including neuropsychological testing.

Methods

A retrospective chart review was completed for the first 18 patients referred for a neuropsychological evaluation from a multidisciplinary pediatric post-COVID clinic. The neuropsychological screening battery assessed verbal fluency and category switching, attention, working memory, processing speed, and verbal learning and memory. Patients’ caregivers also completed standardized questionnaires regarding day-to-day mood and behavior.

Results

At intake, the most common neurologic symptoms reported by caregivers were attention problems (83.3%), fatigue/lethargy (77.7%), sleep disturbance (77.7%), dizziness/vertigo (72.2%), and headaches (72.2%). On rating scales, most caregivers endorsed concerns for depressed mood and anxiety (14/15 and 12/15). A large proportion of patients had difficulties with attention (9/18) and depressed mood/anxiety (13/18) before COVID. On cognitive testing, the majority of the patients performed within or above broad average range (≥16th percentile) across most domains. However, a little over half of the patients performed below average on auditory attention measures.

Conclusions

Within our clinically referred sample, children who reported lingering cognitive symptoms after COVID-19 often had a preexisting history of attention and/or mood and anxiety concerns. Many of these patients performed below average in attention testing, but it remains to be seen whether this was due to direct effects of COVID, physical symptoms, and/or preexisting difficulties with attention or mood/anxiety.

Context-Specificity of Locomotor Learning Is Developed during Childhood

Humans can perform complex movements with speed and agility in the face of constantly changing task demands. To accomplish this, motor plans are adapted to account for errors in our movements because of changes in our body (e.g., growth or injury) or in the environment (e.g., walking on sand vs ice). It has been suggested that adaptation that occurs in response to changes in the state of our body will generalize across different movement contexts and environments, whereas adaptation that occurs with alterations in the external environment will be context-specific. Here, we asked whether the ability to form generalizable versus context-specific motor memories develops during childhood. We performed a cross-sectional study of context-specific locomotor adaptation in 35 children (3-18 years old) and 7 adults (19-31 years old). Subjects first adapted their gait and learned a new walking pattern on a split-belt treadmill, which has two belts that move each leg at a different speed. Then, subjects walked overground to assess the generalization of the adapted walking pattern across different environments. Our results show that the generalization of treadmill after-effects to overground walking decreases as subjects' age increases, indicating that age and experience are critical factors regulating the specificity of motor learning. Our results suggest that although basic locomotor patterns are established by two years of age, brain networks required for context-specific locomotor learning are still being developed throughout youth.

Pediatric Stroke: Unique Implications of the Immature Brain on Injury and Recovery

Pediatric stroke causes significant morbidity for children resulting in lifelong neurological disability. Although hyperacute recanalization therapies are available for pediatric patients, most patients are ineligible for these treatments. Therefore the mainstay for pediatric stroke treatment relies on rehabilitation to improve outcomes. Little is known about the ideal rehabilitation therapies for pediatric patients with stroke and the unique interplay between the developing brain and our models of stroke recovery. In this review, we first discuss the consequences of pediatric stroke. Second, we examine the scientific evidence that exists between the mechanisms of recovery and how they are different in the pediatric developing brain. Finally, we evaluate potential interventions that could improve outcomes.

Transcranial Magnetic Stimulation for the Treatment of Pediatric Neurological Disorders

PURPOSE OF REVIEW

Repetitive transcranial magnetic stimulation (rTMS) is a form of noninvasive brain stimulation that is used for the treatment of migraine and major depression in adults and is now being evaluated for use in other disorders. The purpose of this review is to summarize the physiology underlying TMS, the safety and tolerability in pediatric patients, and the evidence for TMS efficacy in the treatment of pediatric neurologic disorders.

RECENT FINDINGS

Studies investigating rTMS for adolescent depression, hemiparesis due to pediatric stroke, autism, and tics/Tourette syndrome have demonstrated some therapeutic benefit. rTMS has been insufficiently studied for migraine in children despite benefits demonstrated for adult migraine. Evidence for rTMS in childhood epilepsy and ADHD remains mixed. Repetitive transcranial magnetic stimulation is emerging as a safe, tolerable, and potentially effective therapeutic strategy in a number of pediatric neurological disorders, though high-quality, randomized controlled trials are needed. Ongoing studies should focus on optimization of treatment protocols, development of biomarkers to identify children who will benefit from the technique, and identification of the most appropriate indicators of response.

Spatial and temporal asymmetries in gait predict split-belt adaptation behavior in stroke

BACKGROUND

Step asymmetries during gait in persons after stroke can occur in temporal or spatial domains. Prior studies have shown that split-belt locomotor adaptation can temporarily mitigate these asymmetries.

OBJECTIVE

. We investigated whether baseline gait asymmetries affected how patients adapt and store new walking patterns.

METHODS

Subjects with stroke and age-matched controls were studied walking at a 2:1 speed ratio on the split-belt during adaptation and assessed for retention of the learned pattern (the after-effect) with both belts at the same speed.

RESULTS

Those with stroke adapted more slowly (P < .0001), though just as much as healthy older adults. During split-belt walking, the participants with stroke adapted toward their baseline asymmetry (eg, F = 14.02, P < .01 for step symmetry), regardless of whether the subsequent after-effects improved or worsened their baseline step asymmetries. No correlation was found between baseline spatial and temporal measures of asymmetry (P = .38). Last, the initial spatial and temporal asymmetries predicted after-effects independently of one another. The after-effects in the spatial domain (ie, center of oscillation difference) are only predicted by center of oscillation difference baseline (F = 15.3, P = .001), while all other parameters were nonsignificant (all Ps > .17). Temporal coordination (ie, phasing) after-effects showed a significant effect only from phasing baseline (F = 26.92, P < .001, all others P > .33).

CONCLUSION

This work demonstrates that stroke patients adapt toward their baseline temporal and spatial asymmetries of walking independently of one another. We define how a given split-belt training session would affect asymmetries in these domains, which must be considered when developing rehabilitation interventions for stroke patients.

Biosafety testing of genetically modified ryegrass (Lolium perenne) using a model for the optimum selection of test invertebrates

Selection of test species for use in biosafety evaluation of genetically modified plants is challenging but important, as regulators in many jurisdictions require tests to determine the potential for adverse environmental impacts before the release of plants into the environment. This contribution provides an example of an evidence-based process whereby species from the receiving environment can be ranked in order of susceptibility to potential impact, and guide test species selection. The case study used for this example was ryegrass, a forage plant, which had been modified to produce elevated levels of the lipid triacylglyceride. The previously described priority ranking of nontarget invertebrates model (PRONTI), designed to rank invertebrates for biosafety testing, has been adapted for use with these plants, which could, potentially, be beneficial to invertebrate populations, and applied to data on 246 known pasture invertebrate species. The output from the model for the top 20 ranked pasture invertebrate species is discussed, the attributes of these are considered along with the level of uncertainty in the information used. Consideration is given to how the model output can be interpreted and used in a biosafety risk assessment. While some subjectivity is involved in establishing the scores, all invertebrate species are subjected to the same analysis, and treated equally. In this way, regulators have a method of a risk assessment that is evidence-based, and transparent in its assumptions thereby avoiding potential for bias.

How does the motor system correct for errors in time and space during locomotor adaptation?

Walking is a complex behavior for which the healthy nervous system favors a smooth, symmetric pattern. However, people often adopt an asymmetric walking pattern after neural or biomechanical damage (i.e., they limp). To better understand this aberrant motor pattern and how to change it, we studied walking adaptation to a split-belt perturbation where one leg is driven to move faster than the other. Initially, healthy adult subjects take asymmetric steps on the split-belt treadmill, but within 10-15 min people adapt to reestablish walking symmetry. Which of the many walking parameters does the nervous system change to restore symmetry during this complex act (i.e., what motor mappings are adapted to restore symmetric walking in this asymmetric environment)? Here we found two parameters that met our criteria for adaptive learning: a temporal motor output consisting of the duration between heel-strikes of the two legs (i.e., "when" the feet land) and a spatial motor output related to the landing position of each foot relative to one another (i.e., "where" the feet land). We found that when subjects walk in an asymmetric environment they smoothly change their temporal and spatial motor outputs to restore temporal and spatial symmetry in the interlimb coordination of their gait. These changes in motor outputs are stored and have to be actively deadapted. Importantly, the adaptation of temporal and spatial motor outputs is dissociable since subjects were able to adapt their temporal motor output without adapting the spatial output. Taken together, our results suggest that temporal and spatial control for symmetric gait can be adapted separately, and therefore we could potentially develop interventions targeting either temporal or spatial walking deficits.

No impact of transgenic nptII-leafy Pinus radiata (Pinales: Pinaceae) on Pseudocoremia suavis (Lepidoptera: Geometridae) or its endoparasitoid Meteorus pulchricornis (Hymenoptera: Braconidae)

To investigate the biosafety to insects of transgenic Pinus radiata D. Don containing the antibiotic resistance marker gene nptII and the reproductive control gene leafy, bioassays were conducted with an endemic lepidopteran pest of New Zealand plantation pine forests and a hymenopteran endoparasitoid. Larvae of the common forest looper, Pseudocoremia suavis (Butler), were fed from hatching on P. radiata needles from either one of two nptII-leafy transgenic clones, or an isogenic unmodified control line. For both unparasitized P. suavis and those parasitized by Meteorus pulchricornis (Wesmael), consuming transgenic versus control pine had no impact on larval growth rate or mass at any age, larval duration, survival, pupation or successful emergence as an adult. Total larval duration was 1 d (3%) longer in larvae fed nptII-2 than nptII-1, but this difference was considered trivial and neither differed from the control. In unparasitized P. suavis larvae, pine type consumed did not affect rate of pupation or adult emergence, pupal mass, or pupal duration. Pine type had no effect on the duration or survival of M. pulchricornis larval or pupal stages, mass of cocoons, stage at which they died, adult emergence, or fecundity. Parasitism by M. pulchricornis reduced P. suavis larval growth rate, increased the duration of the third larval stadium, and resulted in the death of all host larvae before pupation. The lack of impact of an exclusive diet of nptII-leafy transgenic pines on the life history of P. suavis and M. pulchricornis suggests that transgenic plantation pines expressing nptII are unlikely to affect insect populations in the field.

Thinking about walking: effects of conscious correction versus distraction on locomotor adaptation

Control of the human walking pattern normally requires little thought, with conscious control used only in the face of a challenging environment or a perturbation. We have previously shown that people can adapt spatial and temporal aspects of walking to a sustained perturbation generated by a split-belt treadmill. Here we tested whether conscious correction of walking, versus distraction from it, modifies adaptation. Conscious correction of stepping may expedite the adaptive process and help to form a new walking pattern. However, because walking is normally an automatic process, it is possible that conscious effort could interfere with adaptation, whereas distraction might improve it by removing competing voluntary control. Three groups of subjects were studied: a control group was given no specific instructions, a conscious correction group was instructed how to step and given intermittent visual feedback of stepping during adaptation, and a distraction group performed a dual-task during adaptation. After adaptation, retention of aftereffects was assessed in all groups during normal treadmill walking without conscious effort, feedback, or distraction. We found that conscious correction speeds adaptation, whereas distraction slows it. Subjects trained with distraction retained aftereffects longest, suggesting that the training used during adaptation predicts the time course of deadaptation. An unexpected finding was that these manipulations affected the adaptation rate of spatial but not temporal elements of walking. Thus conscious processes can preferentially access the spatial walking pattern. It may be that spatial and temporal controls of locomotion are accessible through distinct neural circuits, with the former being most sensitive to conscious effort or distraction.

Effects of visual impairment on stroke parameters in Paralympic swimmers

PURPOSE

To examine the relationship between degree of vision and stroking parameters in male and female Paralympic swimmers with visual impairment during the 50- and 100-m freestyle events.

METHODS

A video analysis was conducted at the 1996 Paralympic Games in which swimmers competed in three groups based on degree of impairment (S11, S12, and S13; S11 least amount of vision). A video camera placed 25 m from the start, perpendicular to the swimming direction, recorded the performance of each swimmer during the clean swim phase. Variables measured included total race time, clean swimming speed (CSS), stroke rate (SR), stroke length (SL), and stroke index (SI = CSS x SL). Comparisons of performance were made between the classes and between men and women.

RESULTS

The men showed no significant differences between S12 and S13 on any of the variables or between all three classes on SL and SI. The S11 swimmers demonstrated a significantly slower total race time and CSS in both events. In the women, an increase in class was associated with a decrease in total race time, faster CSS, and increase in SI. In comparing men and women, men demonstrated a significantly faster CSS and total race time during both events, whereas no differences were observed in SR.

CONCLUSION

Stroke parameters during the clean swim phase were affected by visual impairment in both men and women. The male classes, however, were not clearly distinct from each other based on the swimming variables measured, as no significant differences were found between S12 and S13 in either event. With the exception of stroke rate and length, performance of the women tended to increase with an increase in class.

Effects of time, temperature, and honey on Nosema apis (Microsporidia: Nosematidae), a parasite of the honeybee, Apis mellifera (Hymenoptera: Apidae)

Newly emerged adult bees were fed with Nosema apis spores subjected to various treatments, and their longevity, proportions of bees infected, and spores per bee recorded. Spores lost viability after 1, 3, or 6 months in active manuka or multifloral honey, after 3 days in multifloral honey, and after 21 days in water or sugar syrup at 33 degrees C. Air-dried spores lost viability after 3 or 5 days at 40 degrees, 45 degrees, or 49 degrees C. Increasing numbers of bees became infected with increasing doses of spores, regardless of their subsequent food (active manuka honey, thyme honey, or sugar syrup). Final spore loads were similar among bees receiving the same food, regardless of dose. Bees fed with either honey had lighter infections than those fed with syrup, but this may have been due to reductions in their longevity. Bees fed with manuka honey were significantly shorter lived, whether infected or not.

The ribosomal RNA gene region of Nosema apis (Microspora): DNA sequence for small and large subunit rRNA genes and evidence of a large tandem repeat unit size

The ribosomal RNA (rRNA) gene region of the microsporidium, Nosema apis, has been examined. A new method for extracting microsporidian genomic DNA from infected host tissue is described. Complete DNA sequence data are presented for the small subunit gene (1242 bp), the internal transcribed space (33 bp), and the large subunit gene (2481 bp to a putative termination point). This is the first time that the complete large subunit rRNA gene has been published for any microsporidian species. DNA sequence is also presented for the regions flanking the 5' end of the small subunit gene and the 3' end of the large subunit gene. The intergenic spacer is shown to be heterogeneous, showing variation in sequence and restriction sites rather than length and containing sequence repeats, which are a characteristic feature of intergenic spacers. The rRNA gene region of N. apis is shown to occur in a head-to-tail, tandemly repeated manner, as in other eukaryotes. This repeat unit is shown to be approximately 18 kb in length. The nucleotide sequence presented has been submitted to the Genbank database under the accession number U97150.

The effects of surface anaesthesia on the autonomic dysreflexia response during functional electrical stimulation

Recently, increases in blood pressure (BP) and concomitant bradycardia, suggestive of autonomic dysreflexia (AD), have been documented during functional electrical stimulation (FES) in individuals with a high spinal cord injury (SCI). If uncontrolled, this response could preclude the safe use of FES among such individuals. FES induced pain is partly related to stimulation of skin nociceptors. Therefore, measures to reduce skin sensitivity may reduce the risk of AD during FES. The purpose of this study was to determine if topical anaesthetic applied over the site of electrical stimulation could minimize the AD cardiovascular and hormonal responses to FES in individuals with SCI above the T6 level. Seven subjects with a SCI above T6 received FES to the quadriceps muscle of each leg under two conditions on two different testing days. The two treatment conditions, topical anaesthetic and placebo creams, were double blinded and randomized. The cream was administered to an area the size of the electrode (10 x 10 cm) 1 h prior to stimulation. Stimulation began at 0 mAmps and increased by 16 mAmps every 2 min until an intensity of 160 mAmps was achieved. HR and BP were measured at each stimulation intensity level. Catecholamines were analyzed three times during the stimulation protocol (pre, mid and post stimulation intensities). At the end of the stimulation protocol, FES induced isometric quadriceps contraction force at 160 mAmps intensity was measured using a hand held dynamometer. As FES stimulation intensity increased, significant rises in systolic and diastolic BP were seen, with a concomitant progressive drop in HR. The AD response to stimulation was not significantly different between the topical anaesthetic and placebo conditions. Serum catecholamine (epinephrine and norepinephrine) levels tended to rise with increasing FES intensity levels but did not reach statistical significance. The two treatment conditions did not significantly affect serum catecholamine levels or FES-induced quadriceps contraction force. In summary, FES application to the quadriceps muscle in high level SCI subjects resulted in significant increases in BP, decreases in HR (AD-like response), a trend towards elevations in catecholamine levels, and no difference in quadriceps muscular strength. However, these responses were unaffected by the use of topical anaesthetic cream on the skin at the stimulation site. This suggests that other mechanisms than skin nociception are operative in FES-induced AD.

Use of nucleotide sequence data to identify a microsporidian pathogen of Pieris rapae (Lepidoptera, Pieridae)

Nucleotide sequence was determined for a portion of genomic DNA which spans the V4 variable region of the small subunit ribosomal RNA gene of an unidentified microsporidium from the cabbage white butterfly, Pieris rapae (174 base pairs). Comparison with equivalent sequence data obtained here for two other microsporidian species, Nosema bombycis (240 base pairs) and Nosema bombi (200 base pairs), and from the GenBank database for 11 other microsporidian species suggests that the unidentified species from P. rapae is most closely related to some Vairimorpha species. Light and electron microscopic observations of the developmental stages of this parasite were in accord with this. Infection experiments conducted at 20 and 26 degrees C demonstrated temperature-dependent dimorphism, with the production of both binucleate free spores (mean dimensions: 3.8 x 1.8 microns; 10-13 polar filament coils) and membrane-bound uninucleate octospores (mean dimensions: 3.1 x 1.9 microns). Macrospores (mean dimensions 8.0 x 2.1 microns) were also observed. Sites of infection were the gut epithelium, the Malpighian tubules, the salivary glands, and the fat body. Infections were found in all insect life stages, including the egg. This microsporidium was found to be indistinguishable from both Nosema mesnili (Paillot) and Microsporidium (Thelohania) mesnili (Paillot) and we propose that these species be combined and transferred to the genus Vairimorpha Pilley.

DNA probes for two Microsporidia, Nosema bombycis and Nosema costelytrae

Two DNA fragments which hybridize specifically with DNA of Nosema bombycis and Nosema costelytrae, respectively, were obtained from genomic DNA of each microsporidian species and sequenced. Neither fragment hybridized with genomic DNA from four other microsporidian isolates tested: Nosema apis, Vairimorpha sp. from cabbage white butterfly (Pieris rapae), and two isolates of Vavraia oncoperae, one from New Zealand grass grubs, Costelytrae zealandica, and another from porina caterpillars, Wiseana spp. The probe for N. bombycis did not hybridize with genomic DNA from N. costelytrae or with DNA from silkworms (Bombyx mori), the primary insect host of this microsporidium. Likewise, the probe for N. costelytrae did not hybridize with genomic DNA from N. bombycis or with DNA from grass grubs (C. zealandica). Both fragments were AT-rich (59 and 79% of total bases, respectively), had G+C/A+T ratios of 0.70 and 0.25, respectively, and represented repeated sequences dispersed throughout the genome.

Dynamic performance assessment of selected sport shoes on impact forces

Few investigators have evaluated the performance characteristics of non-running sport shoes. The purpose of this study was to assess the dynamic performance characteristics of four different shoe models during landings. Five male subjects performed 25 voluntary hanging drop landings (60 cm) onto a force platform (1000 Hz) for each of four shoe conditions (C1 and C2 = basketball shoe, C3 = running shoe, C4 = volleyball shoe). Ground reaction force data were evaluated for maximum forefoot (F1) and rearfoot (F2) impact forces as well as the respective times of occurrence of these events (T1, T2). Results of the group data analysis indicated a preferential performance rank order of C1, C3, C4, C2 although significant interaction effects were observed, indicating a need for single-subject analyses. Three techniques were incorporated to assess individual subject condition differences, all of which elicited unique rank orders for the shoes although each identified C1 as the "best" shoe condition. The results of the study support the necessity for within-subject analyses conducted with an adequate number of trials when attempting to detect subtle performance differences that may exist between various sport shoes. Whether the observed statistically significant differences are biomechanically meaningful remains an important unanswered question.

Osteoid osteoma: excision with scintimetric guidance

The definite diagnosis of osteoid osteoma relies on the demonstration of the nidus, best shown by CT, which also provides precise preoperative localization of the nidus. While bone-block excision to remove the nidus is feasible in the long bones, there may be unacceptable sequelae in the vertebral column and small bones of the hands. By precisely localizing the nidus, radionuclide scintimetry permits excellent therapeutic results, with minimal morbidity.

Kinetics of technetium 99m labelled macroaggregated albumin in humans

The uptake and elimination of 99Tcm labelled MAA were followed by gamma camera and computer over a period of 36 hours in patients undergoing lung scanning and venography. Lungs, stomach, kidneys, GI tract, bladder and thyroid showed significant concentrations of activity at various times after the injection of radiopharmaceutical, with carefully controlled labelling efficiency. There was no indication of accumulation in the liver or spleen. Activity versus time curves were constructed. The lung curve had approximately bi-exponential form with components of effective half-lives 0.88 and 4.56 h. Areas beneath the curves gave cumulated activities for each organ and, using S values (absorbed dose per unit cumulated activity) from MIRD tables, absorbed doses from self-irradiation were calculated for each organ.