MARCKS and PI(4,5)P2 reciprocally regulate actin-based dendritic spine morphology

Myristoylated, alanine-rich C-kinase substrate (MARCKS) is an F-actin and phospholipid binding protein implicated in numerous cellular activities, including the regulation of morphology in neuronal dendrites and dendritic spines. MARCKS contains a lysine-rich effector domain that mediates its binding to plasma membrane phosphatidylinositol-4,5-biphosphate (PI(4,5)P2) in a manner controlled by PKC and calcium/calmodulin. In neurons, manipulations of MARCKS concentration and membrane targeting strongly affect the numbers, shapes, and F-actin properties of dendritic spines, but the mechanisms remain unclear. Here, we tested the hypothesis that the effects of MARCKS on dendritic spine morphology are due to its capacity to regulate the availability of plasma membrane PI(4,5)P2. We observed that the concentration of free PI(4,5)P2 on the dendritic plasma membrane was inversely proportional to the concentration of MARCKS. Endogenous PI(4,5)P2 levels were increased or decreased, respectively, by acutely overexpressing either phosphatidylinositol-4-phosphate 5-kinase (PIP5K) or inositol polyphosphate 5-phosphatase (5ptase). PIP5K, like MARCKS depletion, induced severe spine shrinkage; 5ptase, like constitutively membrane-bound MARCKS, induced aberrant spine elongation. These phenotypes involved changes in actin properties driven by the F-actin severing protein cofilin. Collectively, these findings support a model in which neuronal activity regulates actin-dependent spine morphology through antagonistic interactions of MARCKS and PI(4,5)P2.

INF2-mediated actin filament reorganization confers intrinsic resilience to neuronal ischemic injury

During early ischemic brain injury, glutamate receptor hyperactivation mediates neuronal death via osmotic cell swelling. Here we show that ischemia and excess NMDA receptor activation cause actin to rapidly and extensively reorganize within the somatodendritic compartment. Normally, F-actin is concentrated within dendritic spines. However, <5 min after bath-applied NMDA, F-actin depolymerizes within spines and polymerizes into stable filaments within the dendrite shaft and soma. A similar actinification occurs after experimental ischemia in culture, and photothrombotic stroke in mouse. Following transient NMDA incubation, actinification spontaneously reverses. Na+, Cl-, water, and Ca2+ influx, and spine F-actin depolymerization are all necessary, but not individually sufficient, for actinification, but combined they induce activation of the F-actin polymerization factor inverted formin-2 (INF2). Silencing of INF2 renders neurons vulnerable to cell death and INF2 overexpression is protective. Ischemia-induced dendritic actin reorganization is therefore an intrinsic pro-survival response that protects neurons from death induced by cell edema.

Growth cone macropinocytosis of neurotrophin receptor and neuritogenesis are regulated by neuron navigator 1

Neuron navigator 1 (Nav1) is a cytoskeleton-associated protein expressed during brain development that is necessary for proper neuritogenesis, but the underlying mechanisms are poorly understood. Here we show that Nav1 is present in elongating axon tracts during mouse brain embryogenesis. We found that depletion of Nav1 in cultured neurons disrupts growth cone morphology and neurotrophin-stimulated neuritogenesis. In addition to regulating both F-actin and microtubule properties, Nav1 promotes actin-rich membrane ruffles in the growth cone and promotes macropinocytosis at those membrane ruffles, including internalization of the TrkB receptor for the neurotrophin brain-derived neurotropic factor (BDNF). Growth cone macropinocytosis is important for downstream signaling, neurite targeting, and membrane recycling, implicating Nav1 in one or more of these processes. Depletion of Nav1 also induces transient membrane blebbing via disruption of signaling in the Rho GTPase signaling pathway, supporting the novel role of Nav1 in dynamic actin-based membrane regulation at the cell periphery. These data demonstrate that Nav1 works at the interface of microtubules, actin, and plasma membrane to organize the cell periphery and promote uptake of growth and guidance cues to facilitate neural morphogenesis during development.

An FPGA-Embedded Brain-Computer Interface System to Support Individual Autonomy in Locked-In Individuals

Brain-computer interfaces (BCI) can detect specific EEG patterns and translate them into control signals for external devices by providing people suffering from severe motor disabilities with an alternative/additional channel to communicate and interact with the outer world. Many EEG-based BCIs rely on the P300 event-related potentials, mainly because they require training times for the user relatively short and provide higher selection speed. This paper proposes a P300-based portable embedded BCI system realized through an embedded hardware platform based on FPGA (field-programmable gate array), ensuring flexibility, reliability, and high-performance features. The system acquires EEG data during user visual stimulation and processes them in a real-time way to correctly detect and recognize the EEG features. The BCI system is designed to allow to user to perform communication and domotic controls.

Web and Cloud Computing to Analyze Microarray Data

Microarray technology is a high-throughput technique that can simultaneously measure hundreds of thousands of genes' expression levels. Web and cloud computing tools and databases for storage and analysis of microarray data are necessary for biologists to interpret massive data from experiments. This chapter presents the main databases and web and cloud computing tools for microarray data storage and analysis.

SIMpLE: A Mobile Cloud-Based System for Health Monitoring of People with ALS

Adopting telemonitoring services during the pandemic for people affected by chronic disease is fundamental to ensure access to health care services avoiding the risk of COVID-19 infection. Among chronic diseases, Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig’s disease, is a progressive neurodegenerative disease of adulthood, caused by the loss of spinal, bulbar and cortical motor neurons, which leads to paralysis of the voluntary muscles and, also, involves respiratory ones. Therefore, remote monitoring and teleconsulting are essential services for ALS patients with limited mobility, as the disease progresses, and for those living far from ALS centres and hospitals. In addition, the COVID 19 pandemic has increased the need to remotely provide the best care to patients, avoiding infection during ALS centre visits. The paper illustrates an innovative, secure medical monitoring and teleconsultation mobile cloud-based system for disabled people, such as those with ALS (Amyotrophic Lateral Sclerosis). The design aims to remotely monitor biosignals, such as ECG (electrocardiographic) and EMG (electromyographic) signals of ALS patients in order to prevent complications related to the pathology.

Biopotential Signal Monitoring Systems in Rehabilitation: A Review

Monitoring physical activity in medical and clinical rehabilitation, in sports environments or as a wellness indicator is helpful to measure, analyze and evaluate physiological parameters involving the correct subject’s movements. Thanks to integrated circuit (IC) technologies, wearable sensors and portable devices have expanded rapidly in monitoring physical activities in sports and tele-rehabilitation. Therefore, sensors and signal acquisition devices became essential in the tele-rehabilitation path to obtain accurate and reliable information by analyzing the acquired physiological signals. In this context, this paper provides a state-of-the-art review of the recent advances in electroencephalogram (EEG), electrocardiogram (ECG) and electromyogram (EMG) signal monitoring systems and sensors that are relevant to the field of tele-rehabilitation and health monitoring. Mostly, we focused our contribution in EMG signals to highlight its importance in rehabilitation context applications. This review focuses on analyzing the implementation of sensors and biomedical applications both in literature than in commerce. Moreover, a final review discussion about the analyzed solutions is also reported at the end of this paper to highlight the advantages of physiological monitoring systems in rehabilitation and individuate future advancements in this direction. The main contributions of this paper are (i) the presentation of interesting works in the biomedical area, mainly focusing on sensors and systems for physical rehabilitation and health monitoring between 2016 and up-to-date, and (ii) the indication of the main types of commercial sensors currently being used for biomedical applications.

Motor-Imagery EEG-Based BCIs in Wheelchair Movement and Control: A Systematic Literature Review

The pandemic emergency of the coronavirus disease 2019 (COVID-19) shed light on the need for innovative aids, devices, and assistive technologies to enable people with severe disabilities to live their daily lives. EEG-based Brain-Computer Interfaces (BCIs) can lead individuals with significant health challenges to improve their independence, facilitate participation in activities, thus enhancing overall well-being and preventing impairments. This systematic review provides state-of-the-art applications of EEG-based BCIs, particularly those using motor-imagery (MI) data, to wheelchair control and movement. It presents a thorough examination of the different studies conducted since 2010, focusing on the algorithm analysis, features extraction, features selection, and classification techniques used as well as on wheelchair components and performance evaluation. The results provided in this paper could highlight the limitations of current biomedical instrumentations applied to people with severe disabilities and bring focus to innovative research topics.

P14.89 Papillary tumor of the pineal region: three cases from a single institution

BACKGROUND

Papillary tumors of the pineal region are highly unusual lesions of unknown incidence. These are neuroepithelial tumors with papillary and solid areas. There is no standardized treatment because of the difficulty to make randomized prospective trials due to its rarity. We report three patients with papillary tumor of the pineal region.

MATERIAL AND METHODS

Retrospective review of the clinical records of patients with papillary tumor of the pineal region at a tertiary neurological center in Buenos Aires, Argentina was done between 2/2012-04/2021. Clinical characteristics, imaging, pathology, treatment and follow-up data were obtained.

RESULTS

Two patients were male and one female. All three patients were adults, two in the fourth decade of life and one in the seventh. Clinical presentation included headache along with either visual symptoms, gait disturbance, or both. Imaging workup included brain and spinal magnetic resonance imaging, finding expanding lesions in the pineal region, hyperintense in FLAIR/T2 sequences, with gadolinium enhancement in T1 with contrast sequence and variable degrees of hydrocephalus. Spinal lesions were not found in these patients. Cerebrospinal fluid cytology was negative in all cases. Tumor biopsy was the initial approach in all cases. Two patients underwent an initial third ventriculostomy procedure but all were submitted to a supracerebellar infratentorial approach for major resection. Posterior treatment included chemoradiotherapy with temozolomide. One patient had a distant recurrence after seven years with and remained with stable disease for two more years, and the other two patients are under control with no recurrence after 2 and 2.5 years respectively.

CONCLUSION

Papillary tumors in the pineal regions are aggressively treated as recurrence is very frequent regarding previous reports (&gt; 70%). Total resection is the only predictive factor associated to better outcome, however, more information is needed in order to achieve treatment consensus.

A Comprehensive Machine-Learning-Based Software Pipeline to Classify EEG Signals: A Case Study on PNES vs. Control Subjects

The diagnosis of psychogenic nonepileptic seizures (PNES) by means of electroencephalography (EEG) is not a trivial task during clinical practice for neurologists. No clear PNES electrophysiological biomarker has yet been found, and the only tool available for diagnosis is video EEG monitoring with recording of a typical episode and clinical history of the subject. In this paper, a data-driven machine learning (ML) pipeline for classifying EEG segments (i.e., epochs) of PNES and healthy controls (CNT) is introduced. This software pipeline consists of a semiautomatic signal processing technique and a supervised ML classifier to aid clinical discriminative diagnosis of PNES by means of an EEG time series. In our ML pipeline, statistical features like the mean, standard deviation, kurtosis, and skewness are extracted in a power spectral density (PSD) map split up in five conventional EEG rhythms (delta, theta, alpha, beta, and the whole band, i.e., 1-32 Hz). Then, the feature vector is fed into three different supervised ML algorithms, namely, the support vector machine (SVM), linear discriminant analysis (LDA), and Bayesian network (BN), to perform EEG segment classification tasks for CNT vs. PNES. The performance of the pipeline algorithm was evaluated on a dataset of 20 EEG signals (10 PNES and 10 CNT) that was recorded in eyes-closed resting condition at the Regional Epilepsy Centre, Great Metropolitan Hospital of Reggio Calabria, University of Catanzaro, Italy. The experimental results showed that PNES vs. CNT discrimination tasks performed via the ML algorithm and validated with random split (RS) achieved an average accuracy of 0.97 ± 0.013 (RS-SVM), 0.99 ± 0.02 (RS-LDA), and 0.82 ± 0.109 (RS-BN). Meanwhile, with leave-one-out (LOO) validation, an average accuracy of 0.98 ± 0.0233 (LOO-SVM), 0.98 ± 0.124 (LOO-LDA), and 0.81 ± 0.109 (LOO-BN) was achieved. Our findings showed that BN was outperformed by SVM and LDA. The promising results of the proposed software pipeline suggest that it may be a valuable tool to support existing clinical diagnosis.

Computational Modeling Reveals Frequency Modulation of Calcium-cAMP/PKA Pathway in Dendritic Spines

Dendritic spines are the primary excitatory postsynaptic sites that act as subcompartments of signaling. Ca²⁺ is often the first and most rapid signal in spines. Downstream of calcium, the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) pathway plays a critical role in the regulation of spine formation, morphological modifications, and ultimately, learning and memory. Although the dynamics of calcium are reasonably well-studied, calcium-induced cAMP/PKA dynamics, particularly with respect to frequency modulation, are not fully explored. In this study, we present a well-mixed model for the dynamics of calcium-induced cAMP/PKA dynamics in dendritic spines. The model is constrained using experimental observations in the literature. Further, we measured the calcium oscillation frequency in dendritic spines of cultured hippocampal CA1 neurons and used these dynamics as model inputs. Our model predicts that the various steps in this pathway act as frequency modulators for calcium, and the high frequency of calcium input is filtered by adenylyl cyclase 1 and phosphodiesterases in this pathway such that cAMP/PKA only responds to lower frequencies. This prediction has important implications for noise filtering and long-timescale signal transduction in dendritic spines. A companion manuscript presents a three-dimensional spatial model for the same pathway.

Post-differentiation Replating of Human Pluripotent Stem Cell-derived Neurons for High-content Screening of Neuritogenesis and Synapse Maturation

Neurons differentiated in two-dimensional culture from human pluripotent stem-cell-derived neural progenitor cells (NPCs) represent a powerful model system to explore disease mechanisms and carry out high content screening (HCS) to interrogate compound libraries or identify gene mutation phenotypes. However, with human cells the transition from NPC to functional, mature neuron requires several weeks. Synapses typically start to form after 3 weeks of differentiation in monolayer culture, and several neuron-specific proteins, for example the later expressing pan-neuronal marker NeuN, or the layer 5/6 cerebral cortical neuron marker CTIP2, begin to express around 4-5 weeks post-differentiation. This lengthy differentiation time can be incompatible with optimal culture conditions used for small volume, multi-well HCS platforms. Among the many challenges are the need for well-adhered, uniformly distributed cells with minimal cell clustering, and culture procedures that foster long-term viability and functional synapse maturation. One approach is to differentiate neurons in a large volume format, then replate them at a later time point in HCS-compatible multi-wells. Some main challenges when using this replating approach concern reproducibility and cell viability, due to the stressful disruption of the dendritic and axonal network. Here we demonstrate a detailed and reliable procedure for enzymatically resuspending human induced pluripotent stem cell (hiPSC)-derived neurons after their differentiation for 4-8 weeks in a large-volume format, transferring them to 384-well microtiter plates, and culturing them for a further 1-3 weeks with excellent cell survival. This replating of human neurons not only allows the study of synapse assembly and maturation within two weeks from replating, but also enables studies of neurite regeneration and growth cone characteristics. We provide examples of scalable assays for neuritogenesis and synaptogenesis using a 384-well platform.

Abstract TP264: Actin Reorganization is a Rapid and Reversible Adaptive Response by Neurons Exposed to Ischemic and Excitotoxic Injury in vitro and in vivo

In initial stages of ischemic injury, glutamate receptor hyperactivation mediates extensive neuronal cell death. Most of this initial death is due to cytotoxic edema, whereby sodium and chloride entry cause cell swelling. Early subcellular responses to neuronal edema are poorly understood. We observed that actin filaments (F-actin) undergo a dramatic reorganization within the somatodendritic domain of neurons exposed to ischemia and/or sublethal excitotoxicity in vivo and in vitro. Fluorescence imaging was performed on embryonic rat hippocampal neurons cultured for 21-days in vitro. “Ministrokes” were induced in vivo by photothrombosis of a single penetrating vessel in mouse sensorimotor cortex. Animals were fixed 4 or 6 hours after vessel occlusion. Fluorescence images were analyzed in infarct, peri-infarct, and contralateral regions. All experiments were repeated 3-4 times, and quantified in a blinded fashion In control tissue F-actin is concentrated within dendritic spines, with little F-actin in the dendrite shaft. Within 5 min of applying 50μM NMDA, F-actin is lost from spines (inducing spine shrinkage) and polymerizes into long filament bundles within the dendrite shaft and soma. A similar redistribution of actin occurs after oxygen/glucose deprivation in vitro and after stroke in vivo. In vitro these actin changes are reversible within 1-3 hours of transient NMDA exposure. Increased Ca2+ is necessary but not sufficient for iniduction. Conditions that reduce cytotoxic edema prevent actinification; conditions that promote cytotoxic edema induce actinfication. The actin nucleator inverted formin-2 (INF2) was found to mediate dendrite actinification. Pharmacological inhibition of formins but not Arp2/3, completely prevented actinification. Moreover, silencing of endogenous INF2 using shRNA prevented NMDA-induced actinification; overexpression of wildtype INF2 sensitized neurons to actinification. Silencing of INF2 rendered neurons more vulnerable to NMDA-induced cell death. Results indicate that ischemia-induced actin filament accumulation within the somatodendritic compartment is a pro-survival response that protects neurons from death induced by cell swelling.

DIETOS: A dietary recommender system for chronic diseases monitoring and management

BACKGROUND AND OBJECTIVE

Use of mobile and web-based applications for diet and weight management is currently increasing. However, the impact of known apps on clinical outcomes is not well-characterized so far. Moreover, availability of food recommender systems providing high quality nutritional advices to both healthy and diet-related chronic diseases users is very limited. In addition, the potentiality of nutraceutical properties of typical regional foods for improving app utility has not been exerted to this end. We present DIETOS, a recommender system for the adaptive delivery of nutrition contents to improve the quality of life of both healthy subjects and patients with diet-related chronic diseases. DIETOS provides highly specialized nutritional advices in different health conditions.

METHODS

DIETOS was projected to provide users with health profile and individual nutritional recommendation. Health profiling was based on user answers to dynamic real-time medical questionnaires. Furthermore, DIETOS contains catalogs of typical foods from Calabria, a southern Italian region. Several Calabrian foods have been inserted because of their nutraceutical properties widely reported in several quality studies. DIETOS includes some well known methods for user profiling (overlay profiling) and content adaptation (content selection) coming from general purpose adaptive web systems.

RESULTS

DIETOS has been validated for usability for both patients and specialists and for assessing the correctness of the profiling and recommendation, by enrolling 20 chronic kidney disease (CKD) patients at the Department of Nephrology and Dialysis, University Hospital, Catanzaro (Italy) and 20 age-matched healthy controls. Recruited subjects were invited to register to DIETOS and answer to medical questions to determine their health status. Based on our results, DIETOS has high specificity and sensitivity, allowing to determine a medical-controlled user's health profile and to perform a fine-grained recommendation that is better adapted to each user health status. The current version of DIETOS, available online at http://www.easyanalysis.it/dietos is not intended to be used by general users, but only for review purpose.

CONCLUSIONS

DIETOS is a novel food recommender system for healthy people and individuals affected by diet-related chronic diseases. The proposed system builds a users health profile and, accordingly, provides individualized nutritional recommendations, also with attention to food geographical origin.

Bioinformatics and Microarray Data Analysis on the Cloud

High-throughput platforms such as microarray, mass spectrometry, and next-generation sequencing are producing an increasing volume of omics data that needs large data storage and computing power. Cloud computing offers massive scalable computing and storage, data sharing, on-demand anytime and anywhere access to resources and applications, and thus, it may represent the key technology for facing those issues. In fact, in the recent years it has been adopted for the deployment of different bioinformatics solutions and services both in academia and in the industry. Although this, cloud computing presents several issues regarding the security and privacy of data, that are particularly important when analyzing patients data, such as in personalized medicine. This chapter reviews main academic and industrial cloud-based bioinformatics solutions; with a special focus on microarray data analysis solutions and underlines main issues and problems related to the use of such platforms for the storage and analysis of patients data.

Assistive device with conventional, alternative, and brain-computer interface inputs to enhance interaction with the environment for people with amyotrophic lateral sclerosis: a feasibility and usability study

OBJECTIVE

To evaluate the feasibility and usability of an assistive technology (AT) prototype designed to be operated with conventional/alternative input channels and a P300-based brain-computer interface (BCI) in order to provide users who have different degrees of muscular impairment resulting from amyotrophic lateral sclerosis (ALS) with communication and environmental control applications.

DESIGN

Proof-of-principle study with a convenience sample.

SETTING

An apartment-like space designed to be fully accessible by people with motor disabilities for occupational therapy, placed in a neurologic rehabilitation hospital.

PARTICIPANTS

End-users with ALS (N=8; 5 men, 3 women; mean age ± SD, 60 ± 12 y) recruited by a clinical team from an ALS center.

INTERVENTIONS

Three experimental conditions based on (1) a widely validated P300-based BCI alone; (2) the AT prototype operated by a conventional/alternative input device tailored to the specific end-user's residual motor abilities; and (3) the AT prototype accessed by a P300-based BCI. These 3 conditions were presented to all participants in 3 different sessions.

MAIN OUTCOME MEASURES

System usability was evaluated in terms of effectiveness (accuracy), efficiency (written symbol rate, time for correct selection, workload), and end-user satisfaction (overall satisfaction) domains. A comparison of the data collected in the 3 conditions was performed.

RESULTS

Effectiveness and end-user satisfaction did not significantly differ among the 3 experimental conditions. Condition III was less efficient than condition II as expressed by the longer time for correct selection.

CONCLUSIONS

A BCI can be used as an input channel to access an AT by persons with ALS, with no significant reduction of usability.

Differential targeting of dynamin-1 and dynamin-3 to nerve terminals during chronic suppression of neuronal activity

Neurons express three closely related dynamin genes. Dynamin 1 has long been implicated in the regulation of synaptic vesicle recycling in nerve terminals, and dynamins 2 and 3 were more recently shown also to contribute to synaptic vesicle recycling in specific and distinguishable ways. In cultured hippocampal neurons we found that chronic suppression of spontaneous network activity differentially regulated the targeting of endogenous dynamins 1 and 3 to nerve terminals, while dynamin 2 was unaffected. Specifically, when neural activity was chronically silenced for 1-2weeks by tetrodotoxin (TTX), the clustering of dynamin 1 at nerve terminals was reduced, while the clustering of dynamin 3 significantly increased. Moreover, dynamin 3 clustering was induced within hours by the sustained blockade of AMPA receptors, suggesting that AMPA receptors may function to prevent Dyn3 accumulation within nerve terminals. Clustering of dynamin 3 was induced by an antagonist of the calcium-dependent protein phosphatase calcineurin, but was not dependent upon intact actin filaments. TTX-induced clustering of Dyn3 occurred with a markedly slower time-course than the previously described clustering of synapsin 1. Potassium-induced depolarization rapidly de-clustered dynamin 3 from nerve terminals within minutes. These results, which have implications for homeostatic synapse restructuring, indicate that the three dynamins have evolved different regulatory mechanisms for trafficking to and from nerve terminals in response to changes in neural activity.

Activity-dependent dendritic spine shrinkage and growth involve downregulation of cofilin via distinct mechanisms

A current model posits that cofilin-dependent actin severing negatively impacts dendritic spine volume. Studies suggested that increased cofilin activity underlies activity-dependent spine shrinkage, and that reduced cofilin activity induces activity-dependent spine growth. We suggest instead that both types of structural plasticity correlate with decreased cofilin activity. However, the mechanism of inhibition determines the outcome for spine morphology. RNAi in rat hippocampal cultures demonstrates that cofilin is essential for normal spine maintenance. Cofilin-F-actin binding and filament barbed-end production decrease during the early phase of activity-dependent spine shrinkage; cofilin concentration also decreases. Inhibition of the cathepsin B/L family of proteases prevents both cofilin loss and spine shrinkage. Conversely, during activity-dependent spine growth, LIM kinase stimulates cofilin phosphorylation, which activates phospholipase D-1 to promote actin polymerization. These results implicate novel molecular mechanisms and prompt a revision of the current model for how cofilin functions in activity-dependent structural plasticity.

Rapid, concurrent alterations in pre- and postsynaptic structure induced by naturally-secreted amyloid-beta protein

In Alzheimer's disease increasing evidence attributes synaptic and cognitive deficits to soluble oligomers of amyloid beta protein (Abeta), even prior to the accumulation of amyloid plaques, neurofibrillary tangles, and neuronal cell death. Here we show that within 1-2 h picomolar concentrations of cell-derived, soluble Abeta induce specific alterations in pre- and postsynaptic morphology and connectivity in cultured hippocampal neurons. Clusters of presynaptic vesicle markers decreased in size and number at glutamatergic but not GABAergic terminals. Dendritic spines also decreased in number and became dysmorphic, as spine heads collapsed and/or extended long protrusions. Simultaneous time-lapse imaging of axon-dendrite pairs revealed that shrinking spines sometimes became disconnected from their presynaptic varicosity. Concomitantly, miniature synaptic potentials decreased in amplitude and frequency. Spine changes were prevented by blockers of nAChRs and NMDARs. Washout of Abeta within the first day reversed these spine changes. Further, spine changes reversed spontaneously by 2 days, because neurons acutely developed resistance to continuous Abeta exposure. Thus, rapid Abeta-induced synapse destabilization may underlie transient behavioral impairments in animal models, and early cognitive deficits in Alzheimer's patients.

Nursing Staff Beliefs and Expectations About Continence Care in Nursing Homes

OBJECTIVE

The purpose of this qualitative study was to consider the current beliefs of nursing assistants and directors of nursing about management of urinary incontinence (UI) among the residents in nursing homes.

DESIGN

This was a qualitative study using purposive sampling and a focus group methodology.

SETTING AND SUBJECTS

Three focus groups including 38 participants were held in 2 different regions. Two of the focus groups comprised nursing assistants and 1 comprised directors of nursing.

METHOD

The focus groups were facilitated by 2 different advanced practice nurses (BR and LJK), and 2 similar interview guides were used: 1 for the nursing assistants and 1 for the nurses. The interviews were tape recorded and transcribed verbatim; data were analyzed via content analysis.

RESULTS

Ten themes were identified from the data; 3 focused on resident factors that influence UI, 4 related to staff and family contributors to UI, and 3 focused on recommendations to improve UI management in the nursing home setting.

CONCLUSIONS

The findings from this study can be used to guide interventions to decrease or eliminate barriers to continence care and thereby facilitate the implementation of clinical practice guidelines and evidence-based interventions to improve urinary continence among nursing home residents.

Development and regulation of dendritic spine synapses

Dendritic spines are small protrusions from neuronal dendrites that form the postsynaptic component of most excitatory synapses in the brain. They play critical roles in synaptic transmission and plasticity. Recent advances in imaging and molecular technologies reveal that spines are complex, dynamic structures that contain a dense array of cytoskeletal, transmembrane, and scaffolding molecules. Several neurological and psychiatric disorders exhibit dendritic spine abnormalities.

Differences in Diabetes Management of Nursing Home Patients Based on Functional and Cognitive Status

OBJECTIVES

To describe practice patterns regarding diabetes management among nursing home (NH) physicians and to identify variation in this practice based on patient characteristics.

DESIGN

Mailed survey.

PARTICIPANTS

Nursing home physicians from the American Medical Directors Association (AMDA) Foundation Long-Term Care Research Network (n = 142), as well as other members of AMDA who were Certified Medical Directors (CMD) (n = 68) and members who were not CMD certified (n = 45). Response rates to the survey were 51%, 33%, and 23%, respectively.

MEASUREMENTS

Physician and facility characteristics were queried. Responses to 12 items pertaining to diabetes management and 5 items pertaining to use of specific oral diabetes medications were evaluated in the context of 3 different patient profiles that reflected different combinations of functional and cognitive impairment. Responses were based on the physicians' perception of how they manage diabetes under these specified patient profiles.

RESULTS

Responses from members of the Research Network indicated highly significant variability (P < .01) between the 3 patient profiles for all of the 12 management items. Ordering a special diet, monitoring lipid panel, and ordering routine ophthalmology was less likely for the patient profile with both functional and cognitive impairment (P < .01). These differences among the patient profiles for these 3 interventions were present in the responses from all 3 categories of physicians (Research Network, CMD, and non-CMD members of AMDA). There was no statistically significant variability among the 3 patient profiles for any of the 3 physician groups regarding the likelihood of using of any of the 5 classes of oral diabetic medications. Non-CMD physicians were more likely to have less NH experience; otherwise, there were no differences among the 3 physician groups.

CONCLUSIONS

Nursing home physicians appear to alter the approach to diabetes management based on the functional and/or cognitive status of the patient. This was particularly true for those physicians who were members of the AMDA Foundation Research Network. These findings have implications for initiatives designed to guide clinical practice as well as efforts by regulatory bodies to evaluate appropriate care. Further research is needed to measure the actual impact of different approaches to diabetes management on relevant outcomes in this population.

Essential Role for the PKC Target MARCKS in Maintaining Dendritic Spine Morphology

Spine morphology is regulated by intracellular signals, like PKC, that affect cytoskeletal and membrane dynamics. We investigated the role of MARCKS (myristoylated, alanine-rich C-kinase substrate) in dendrites of 3-week-old hippocampal cultures. MARCKS associates with membranes via the combined action of myristoylation and a polybasic effector domain, which binds phospholipids and/or F-actin, unless phosphorylated by PKC. Knockdown of endogenous MARCKS using RNAi reduced spine density and size. PKC activation induced similar effects, which were prevented by expression of a nonphosphorylatable mutant. Moreover, expression of pseudophosphorylated MARCKS was, by itself, sufficient to induce spine loss and shrinkage, accompanied by reduced F-actin content. Nonphosphorylatable MARCKS caused spine elongation and increased the mobility of spine actin clusters. Surprisingly, it also decreased spine density via a novel mechanism of spine fusion, an effect that required the myristoylation sequence. Thus, MARCKS is a key factor in the maintenance of dendritic spines and contributes to PKC-dependent morphological plasticity.

A+ Asthma Rural Partnership coloring for health: an innovative rural asthma teaching strategy

Asthma is the leading chronic illness in children, affecting about 4.8 million children in the United States. Recent reports indicate a lack of asthma educational resources for rural school health nurses to use in their practice. This article describes the development of the My Asthma Coloring Book educational tool for children and their families living in rural communities. My Asthma Coloring Book was developed to provide asthma information in a short-story format for children with asthma. The coloring book content is described, including its utilization as part of the A+ Asthma Rural Partnership research project funded by the National Institute of Nursing Research (R01NR05062-01).

The A-like potassium current of a leech neuron increases with age in cell culture

Single leech neurons isolated and maintained in culture sprout and form electrical and chemical synapses, as they do in vivo, retaining most of the electrical properties of the intact membrane. However, some cells, such as Retzius, Anterior Pagoda (AP) cells and motoneurons, exhibit consistent changes of biophysical characteristics, which mimic those induced by axotomy in vivo and are reversed after reconnection. To improve our understanding of the mechanisms involved in these alterations and of their physiological significance, we investigated the early changes in outward currents developed by cultured AP neurons, using the patch-clamp technique in the whole-cell recording configuration. Different currents were isolated and a differential sensitivity to the time spent in culture and to internal calcium was observed. Three potassium currents were dissected: an A-like current, a delayed rectifier and a third unidentified component. The A-like potassium current was significantly increased with neuronal age in cell culture and was a function of the internal Ca(2+) concentration, whereas the two other potassium currents remained unchanged. Intracellular recordings performed from axotomized neurons of cultured ganglia revealed clear-cut alterations in spike adaptation, which might be due to changes of the A-like current.

Mechanosensitivity of N-type calcium channel currents

Mechanosensitivity in voltage-gated calcium channels could be an asset to calcium signaling in healthy cells or a liability during trauma. Recombinant N-type channels expressed in HEK cells revealed a spectrum of mechano-responses. When hydrostatic pressure inflated cells under whole-cell clamp, capacitance was unchanged, but peak current reversibly increased ~1.5-fold, correlating with inflation, not applied pressure. Additionally, stretch transiently increased the open-state inactivation rate, irreversibly increased the closed-state inactivation rate, and left-shifted inactivation without affecting the activation curve or rate. Irreversible mechano-responses proved to be mechanically accelerated components of run-down; they were not evident in cell-attached recordings where, however, reversible stretch-induced increases in peak current persisted. T-type channels (alpha(1I) subunit only) were mechano-insensitive when expressed alone or when coexpressed with N-type channels (alpha(1B) and two auxiliary subunits) and costimulated with stretch that augmented N-type current. Along with the cell-attached results, this differential effect indicates that N-type mechanosensitivity did not depend on the recording situation. The insensitivity of T-type currents to stretch suggested that N-type mechano-responses might arise from primary/auxiliary subunit interactions. However, in single-channel recordings, N-type currents exhibited reversible stretch-induced increases in NP(o) whether the alpha(1B) subunit was expressed alone or with auxiliary subunits. These findings set the stage for the molecular dissection of calcium current mechanosensitivity.

Asthma management practices and education needs of head start directors and staff

Limited information exists regarding asthma management practices and education needs of Head Start directors and staff. This paper describes asthma management practices and education needs of Head Start directors and staff in 15 Baltimore, Md., Head Start programs. From February to December 2000, all Head Start staff and directors were asked to complete a survey. Data from 268 Head Start staff and 12 Head Start directors were analyzed. Results revealed discrepancies between Head Start staff and directors regarding location of asthma medications and presence of asthma action plans in programs. Both Head Start staff and directors stated they had no curriculum to teach Head Start children how to manage asthma. This finding provides evidence that asthma education is needed in Head Start programs. Findings also indicate a need for improved communication between Head Start directors and staff.

Role of rural school nurses in asthma management

Environmental, socioeconomic, psychological and familial factors in rural communities predispose children to asthma. This is not only the case in the US but also in the UK, New Zealand and other Western countries. Asthma prevalence ranges from 2.2 to 15%. Because children spend at least 6 hours of their day in school, school health personnel must be attentive to, and skilled in managing the needs and issues faced by children with asthma while at school. Rural school nurses or their deputies need to advise children with asthma about avoiding aeroallergens from hay, smoke, dust, grain in silos and animal dander from cattle and sheep. In the case of children with asthma in rural areas, symptoms may be accepted as long as the child can go to school and play. Parents in rural areas may not believe in routine preventive care for asthma as part of public health practice. Rural nurses need to be aware of current asthma guidelines and apply the concepts to prevention. They need to be proactive and engage in primary, secondary and tertiary prevention. Rural school nurses can begin by using existing resources and adapting these resources for use in rural school environments. Worldwide asthma education is fundamental to asthma patient management.

Rural school nurses' asthma education needs

School nurses play an important role in identifying children with asthma and providing care during school hours. Educational programs designed to improve nurses' asthma knowledge and practices have concentrated on urban settings. The purpose of this investigation was to determine asthma-related practices and educational needs of rural school nurses. A survey about asthma was mailed to school nurses in all counties of the state of Maryland and in Washington, D.C. Responses were compared between rural Maryland counties and counties from the remainder of Maryland and Washington, D.C. The survey addressed attitudes and beliefs, function and roles, medication administration, and educational needs about asthma. We found that rural nurses used peak flow meters less often to assess and monitor asthma, requested fewer referrals for asthma, had fewer interactions with health room assistants, and had reduced access to asthma educational resources. Also, they provided less asthma education in the schools than other school nurses. These results suggest a need for comprehensive asthma educational programs in rural areas that are based on national guidelines, and that address the unique needs of rural school nurses. These programs should also emphasize the need for open communication between rural school nurses, health room assistants, primary care providers, and parents/caregivers.

Asthma education in rural communities

Asthma is a common disease of airway obstruction in school-aged children. Adequate management of asthma in children leads to fewer missed school days, fewer hospitalizations, fewer emergency room visits, and an increase in quality of life. Most asthma educational programs and evaluations have focused on urban rather than rural populations. The purpose of this study was to identify parental asthma needs, develop rural asthma education materials, and evaluate the effectiveness of these educational materials in improving the knowledge and asthma care effectiveness of parents of children with asthma in a rural community. Seven parents were contacted by telephone and administered a pre- and posttest questionnaire analyzing their level of knowledge about asthma and their quality of life. Asthma educational materials were mailed to all parents in the study before administering the posttest. Results indicated that all parents needed additional education about asthma, especially regarding medications. Pre- and posttest scores showed improvements in three areas of knowledge: long-term asthma medications, controlling roaches in the home, and daily peak flow monitoring. There was a significant improvement between pre- and posttest results from the activity domain of quality of life. Eighty-five percent of the parents reported that they had either initiated changes in their home, or planned to in the future, from reading the educational materials. The parents' response to the educational materials that they received by mail was positive, indicating that they may not have received enough information about how to care for children with asthma before our study. The data suggest that distribution of asthma educational materials in rural communities can increase parental knowledge about asthma and lead to positive changes in behavior that can improve their children's health.

Stretch-activated cation channels of leech neurons: characterization and role in neurite outgrowth

The goal of this study was to characterize the stretch-activated ion channels (SACs) of adult identified neurons of the leech Hirudo medicinalis and to test the role of SACs in neurite outgrowth of isolated cells. Using cell-attached patch recording, we established that SACs are densely distributed in the growth cone membrane of cultured neurons. In excised patches, we found that these channels are permeable to Ca2+, as well as to monovalent cations. The channels are blocked by the extracellular application of gadolinium (Gd3+), amiloride and gentamicin. Amiloride and gentamicin, respectively, induce a partial and complete voltage-dependent block. Time-lapse video recordings of neurite outgrowth from single cultured neurons were used to study the effects of blocking SACs with gentamicin. Within 20 h of plating in the presence of the aminoglycoside, the total length of neuronal arborization was significantly greater than that measured in its absence. The amount of assembled axon per unitary surface area remained constant over 40 h and did not differ significantly with or without gentamicin. Our findings show that SACs of leech neurons admit Ca2+, are densely distributed in the growth cone membrane and exhibit typical pharmacological features of mechanotransducer ion channels. In addition, our data suggest that these cation channels participate in the early interaction between growing neurites and culture substrate.

Stretch-sensitive ion channels of neuronal growth cones

This paper unifies and outlines some important points made by recent experimental work, dealing with MS ion channels and growth cone motility. The considerable work carried out in cell biology, neurochemistry and membrane biophysics in the past decade allows us to imagine the neurite growth in term of known molecules and chains of simple mechanisms. On the other hand, it is becoming increasingly clear the real complexity of the growth cone behavior. There remain important gaps in our understanding of the role of MS channels in growth cone motility. At present, a major limitation for physiological work is the lack of specific blockers. An encouraging development of molecular genetic studies of Drosophila SAK channels (60) will probably provide valuable tools for straightforward experiments.

Remodelling of an intact neurone in the central nervous system of the leech

The regeneration pattern of two identified central neurones was studied in the leech Hirudo medicinalis. Anterior pagoda (AP) and mechanosensory touch-sensitive (T) neurones were stained in adult segmental ganglia, maintained in culture for 6-10 days. AP neurones, which normally project only to the contralateral nerve roots, sprouted extensively in all the available nerve paths during regeneration. Mechanosensory T cells, in the same experimental conditions, showed only a moderate growth and did not change their normal pattern of axonal projections. The observed differences in the growth pattern might account for the different electrophysiological responses to axotomy exhibited by the two types of neurone. Interruption of interganglionic connectives induced a moderate and stereotyped remodelling of the morphology of intact AP neurones, which was reminiscent of that transiently exhibited during embryonic development. This response was observed in 25% of the AP neurones we examined.

[Venous grafts in reimplantation of the thumb]

The Authors analyze their experience of 25 thumb reimplantations and revascularizations within 5 years. The importance of the first finger in the functional hand economy as well as the ratio between reimplantation take rate and degree of functional recovery with regard to the type of trauma, technique used, and possible and incidental complications are underlined. The venous autologous grafts are of great importance in this microsurgical area and they are more and more applied. In most cases, indeed, intimal lesions are more extended than their macroscopic appearance and the tract of damaged vessels is always wider than assessed. The graft interposition solves the problem with the further advantage to preserve the maximal bone length and to avoid especially contaminated areas. The results achieved confirm these statements and the Authors conclude for the absolute need of venous grafts in thumb reimplantations, especially after amputation from avulsion or crush traumas, even though a greater skill is necessary in using this technique.

[Latissimus dorsi flap in reconstructive surgery of the lower limbs]

The free latissimus dorsi flap has been used to repair 10 complex losses of substance of the lower extremity. The results have shown the great reconstructive potentialities of the microvascular transfer of this muscle, considered by the authors the most versatile of the myocutaneous flaps. Among the advantages there are the extended surface, its thickness, its pedicle with adequate length and diameter as well as the absence of functional involvement, especially by preserving the upper branch of the thoracodorsal nerve. The indications, however, are limited due to a significant rate of complications which prevent its extended use.