Structure, Process and Outcomes in Patient Engagement

Although patient engagement in research is gaining acceptance by researchers and funding bodies, descriptions of implementation options and associated outcomes are limited. In this appreciative inquiry of the 12 institutions involved in the Great Plains Collaborative of the Patient-Centered Outcomes Research Network (PCORnet), we interviewed patient engagement officers and patient partners to enhance understanding of approaches to organizational structure, research engagement processes, and associated outcomes of the engaged research. Multiple structures have been identified including operational affiliations in both hospital and multiple university departments. Professional affiliations of patient engagement officers vary widely, including nurses, social workers, and public health professionals, among others. Patient engagement processes also vary, but with the majority using forms of advisory boards. All sites reported outcomes of their work including completed and/or ongoing research and co-authored publications.

Methodological considerations for the design and implementation of a fully longitudinal mixed methods study

Growing interest is evident in longitudinal mixed methods research, particularly fully longitudinal mixed methods designs in which both quantitative and qualitative data are collected concurrently for the duration of the study. Fully longitudinal mixed methods designs are particularly relevant for research on dynamic phenomena because of their ability to illuminate both quantitative and qualitative dimensions of change in real time as the phenomenon of interest changes. However, these are complex research designs and their data-intense nature makes them potentially burdensome for study participants, challenging for research teams, and costly for funding agencies. Despite growing use, the methodological literature on fully longitudinal mixed methods research is sparse and little guidance is available for researchers considering this approach. We address this gap by describing our experience with the design and implementation of a fully longitudinal mixed methods study of a dynamic phenomenon, namely, family caregiving during cancer treatment. We describe important questions and key decisions confronted while developing the research proposal, proactive strategies for study implementation, and implementation realities encountered while the study was in progress. On the basis of insights gained through real-world experience, we offer three guiding principles for researchers undertaking such a study. First, align the study design with the nature of the dynamics in the phenomenon of interest. Second, plan from the start when and how the integration of the longitudinal quantitative and qualitative data will occur. Third, employ implementation strategies that take into account the practical aspects of repeated contacts with study participants for an extended period.

Use of Comprehensive Participatory Planning and Evaluation in Rural Patient Engagement

Comprehensive participatory planning and evaluation (CPPE), a model used in community engagement research, has not been applied to patient engagement in research. We describe our methodology and interim results using CPPE in a project focused on improving research engagement of rural and distant patients and stakeholders. Specifically, we describe our development of a causal map and the subsequent use of the map to guide patient and stakeholder-driven evaluation.

Photophysical properties of Na+ -indicator dyes suitable for quantitative two-photon fluorescence-lifetime measurements

Two-photon microscopy (2PM) offers great potential in fluorescence imaging of intracellular Na⁺ dynamics of live cells. A severe drawback, however, is that quantitative ratioing of fluorescence intensities at different wavelengths [possible in one-photon imaging with the classical Na⁺ -indicator dye sodium-binding benzofuran isophtalate (SBFI)] is not practical in 2PM. We aimed at establishing 2PM-based time-correlated fluorescence lifetime measurements as an alternative method for quantifying Na⁺ dynamics. We compared the photophysical properties of the four Na⁺ -sensitive fluorescent indicator dyes SBFI, CoroNa Green, Sodium Green and Asante NaTRIUM Green-2 (ANG-2) in cuvette calibrations. All four dyes showed Na⁺ -dependent intensity changes, with ANG-2 having the most favourable properties for 2PM. All dyes but SBFI showed significant changes in their fluorescence lifetime upon Na⁺ binding, again with ANG-2 being the most promising dye. We found that, unfortunately, the fluorescence lifetime of ANG-2 is not only affected by Na⁺ but also by protons, K⁺ and dye impurities, rendering a quantitative description of the individual lifetime components impractical. However, a simplified calibration procedure, based on a published approach for Ca²⁺ imaging, allowed relating lifetimes to Na⁺ concentration. Using ANG-2 and the simplified calibration will allow quantitative two-photon Na⁺ imaging with millimolar sensitivity.

LAY DESCRIPTION

Dynamic changes of ion concentrations, which play crucial roles in cellular physiology, can be monitored with appropriate fluorescent indicator dyes. For intracellular sodium ions (Na⁺ ), certain dyes even allow quantitative measurements with standard microscopic techniques. However, for two-photon microscopy, which allows resolving cells deep in intact tissue, imaging solutions that are fully quantitative are lacking. For the four commercially available Na⁺ dyes 'SBFI', 'CoroNa Green', 'Sodium Green', and 'Asante NaTRIUM Green-2' (ANG2) we analyzed whether their fluorescent lifetime (LT), i.e., the nanosecond decay of emission of photons after a pulsed excitation, could serve as a quantitative measure of intracellular Na⁺ . Pulsed excitation in the femtosecond range is an inherent feature of two-photon microscopy and, in combination with fast, single-photon counting microscopes, allows for easy-to-implement LT microscopy. We found that Sodium Green and ANG2 showed strong Na⁺ -dependent changes in the fluorescence LT, while SBFI showed no, and CoroNa Green only small changes. ANG2, as the brightest dye, was further characterized regarding effects of protons and potassium ions (K⁺ ), both also present in cells at significant concentrations, on the fluorescence LT. We found that the LT of ANG2 is affected in a predictable manner by Na⁺ , K⁺ , and protons. However, our data reveal that the commercial dye must also contain impurities with unexpected Na⁺ - and K⁺ -binding characteristics, rendering a quantitative description of the individual lifetime components impractical. We, therefore, adapted a simplified calibration procedure, based on a published approach for Ca²⁺ imaging, that allows relating the average lifetime to Na⁺ concentration. With this simplified calibration procedure, ANG2 is well suited for quantitative two-photon Na⁺ imaging with millimolar sensitivity.

The lived experience of parents and guardians providing care for child transplant recipients

CONTEXT

Little has been published about the caregiving experiences of the parents or guardians of children receiving liver or liver/intestinal transplants.

OBJECTIVE

To describe the lived experiences of parents and guardians as they prepared for and provided postdischarge care to a child who received an isolated intestine or a liver/intestinal transplant and to assess the impact of transplants on parents' stress levels.

DESIGN

Semistructured, audio-taped phone interviews of parents' and guardians' perceptions of their experiences preparing to and providing care to a child transplant recipient were transcribed verbatim and analyzed by the research team using established qualitative research methods.

PARTICIPANTS

Five parents or guardians (3 mothers, 1 foster mother, and 1 grandfather) of children who received a transplant between 2000 and 2008 at age 11 months to 6.7 years.

RESULTS

Responses to the interviews gravitated toward 3 focal points: the parents' and guardians' perceptions of their interactions with the transplant team, their interactions with the local health care systems, and caring for themselves and their child at home.

CONCLUSION

In preparing parents and guardians to care for their children after discharge from the hospital, transplant teams need to be aware of differences between what we think we communicate and how it is interpreted by the parents and guardians, the relationships built between parents and guardians and health care teams, parents' attitudes and levels of stress, and the impact these factors have on care and the parents' and guardians' experience.

Prevention and management of oral mucositis in patients with cancer

OBJECTIVES

To review current evidence that applies to the development of a nursing plan of care for the prevention and treatment of oral mucositis related to cytotoxic therapy.

DATA SOURCES

Research studies, review articles, evidence-based guidelines, web-based material, and clinical experience.

CONCLUSION

Although high-level research evidence regarding mucositis is limited, use of multiple types of evidence in developing a structured plan of care facilitates improved patient outcomes and the advancement of the current body of knowledge.

IMPLICATIONS FOR NURSING PRACTICE

Nurses play a key role in the identification and use of evidence to guide the care of patients at risk for cytotoxic therapy-related oral mucositis.

Nursing Interventions and Supportive Care for the Prevention and Treatment of Oral Mucositis Associated with Cancer Treatment

PURPOSE/OBJECTIVES

To review novel approaches to assessing and managing patients with cancer who are at risk for oral mucositis.

DATA SOURCES

Published research and review articles, books, conference presentations, and abstracts.

DATA SYNTHESIS

Oral mucositis is a major source of clinical morbidity among patients with cancer undergoing treatment, yet definitive management strategies continue to elude practitioners. A growing body of evidence suggests that a multifaceted, innovative, targeted approach to oral care provides an important foundation with which to reduce treatment-related morbidity.

CONCLUSIONS

Ongoing assessment and monitoring are critical to the effective management of oral mucositis. Targeted interventions that incorporate the basic principles of wound care with current knowledge about the temporal aspects of clinical manifestations, evidence-based standardized approaches to assessment, and utilization of novel therapeutics provide an important means by which to improve patient outcomes.

IMPLICATIONS FOR NURSING

Oral care protocols are essential components of oral mucositis management. Incorporating current knowledge of pathophysiology with a targeted, standardized approach may help to reduce overall morbidity and improve quality of life.

Independent Nursing Actions in Cooperative Care

PURPOSE/OBJECTIVES

To identify and describe independent nursing actions in cooperative care.

DESIGN

Qualitative, descriptive, inductive study.

SETTING

The Nebraska Medical Center's Lied Transplant Center in Omaha, where lay care partners assume responsibility for acute care of transplant recipients in partnership with nurses.

SAMPLE

12 cooperative care nurses.

METHODS

Two focus groups, 59 narrative logs, and three follow-up interviews were tape recorded, transcribed, and content analyzed.

MAIN RESEARCH VARIABLE

Independent nursing actions in cooperative care.

FINDINGS

Independent nursing actions included surveillance, teaching, coaching, fostering partnerships, providing psychosocial support, rescuing, and coordinating. Surveillance leads to problem identification that, in turn, triggers other actions. Because all nursing actions occur in the context of nurse, dyad, and healthcare team relationships, coordinating is the category of nursing action used to manage all aspects of care.

CONCLUSIONS

The nurses integrated specialized knowledge and expertise while dynamically using surveillance to identify problems that trigger nursing actions to manage signs and symptoms. Cooperative care is an example of apprenticeship or guided participation in which a community of experts (nurses) guides, supports, and challenges novices (lay individuals) to participate in skilled activities until the responsibility for the activities can be transferred to the novice.

IMPLICATIONS FOR NURSING

Independent nursing actions identified in this study are the first step in formulating an instrument to measure "doses" (frequency and intensity) of nursing actions in cooperative care. Such an instrument is needed to evaluate interventions designed to prepare and support lay care partners.

Identification and Validation of Competencies for Use in Objective Structured Clinical Examinations for Lay Caregivers

Cancer care has shifted from the traditional hospital to alternative settings, thus requiring lay individuals to assume increased direct care responsibility. Cooperative Care is an example of an alternative acute care delivery model where a family member or a friend is responsible for care previously provided by healthcare professionals. The success of alternative models is dependent on effective educational programs with clearly defined expectations and methods for evaluating caregiver competence. Objective structured clinical examinations (OSCEs) provide a standardized approach to evaluating caregiver performance in a simulated situation. The purpose of the first phase of this instrument development project was to identify and validate competencies for inclusion in OSCEs to be used with lay caregivers in preparation for Cooperative Care. The study included multiple methods of data collection: analysis of documents, viewing videos, observation with note taking, and a focus group session. All classes and materials provided for lay caregivers were reviewed. Core content domains and competencies were identified and used to develop OSCEs. A focus group of healthcare providers responsible for the education and care of patients and their caregivers validated the competencies embedded within the OSCEs. This study demonstrated the efficacy of the approach used for the identification and validation of competencies for lay caregivers.

Tracking patient education documentation across time and care settings

Results of a formative evaluation of a patient education documentation system will be presented. Both quantitative and qualitative approaches to data collection are being used. The goal of integrating patient education documentation into the electronic patient record is to facilitate seamless, multidisciplinary patient/family education across time and settings. The system is being piloted by oncology services at The Nebraska Medical Center. The evaluation addresses the usability and comprehensiveness of the system.

Assessment and measurement of oral mucositis

OBJECTIVE

To discuss the assessment and monitoring of mucositis and provide an overview of instruments available to assess or measure mucositis.

DATA SOURCE

Published journal articles, texts, and clinical experience.

CONCLUSION

The lack of consistent use of valid and reliable instruments for the assessment of mucositis have limited progress in the prevention and management of mucositis.

IMPLICATIONS FOR NURSING PRACTICE

Nurses play a key role in the assessment of oral cavity changes. Using valid and reliable measures will foster the ability to predict risk for mucositis and to test the effectiveness of protocols for its prevention and treatment.

Evaluation of a nurse care planning system that uses evidence-based order sets

The results of an evaluation of a nurse care planning (NCP) system that is based on the use of evidence-based order sets will be presented. The integration of the nurse care planning function into the clinical information system (CIS) at Nebraska Health System (NHS) was implemented in March, 2003. The evaluation addresses the usability and completeness of the order sets to plan and direct nursing care.

Defining clinically meaningful outcomes in the evaluation of new treatments for oral mucositis: oral mucositis patient provider advisory board

Oral mucositis (OM)-related outcomes constituting a meaningful clinical advance in bone marrow transplant patients were considered by an interdisciplinary panel. Meaningful outcomes are essential in product development for OM, a condition without effective prevention or treatment. The most important outcomes to measure, the feasibility of measuring these in a clinical trial, and clinically meaningful differences in these outcomes were determined by the panel. Most important are reduction in oral pain and use of opioid analgesics, improvement in oral intake and quality of life, and reduction of hospitalization duration. Reduction in the severity of OM measured by an objective evaluation of oral mucosa could provide insight regarding the biologic activity of an intervention. Further data are required to define the precise relationship between reduction in visible OM and improvement in outcome. Minimally, clinical trials for OM should assess oral pain, opioid use, oral intake, and include objective assessment of OM.

Argus: a new instrument for the measurement of the stratospheric dynamical tracers, N2O and CH4

We describe here a new instrument for the simultaneous, in situ measurement of the stratospheric tracer molecules, nitrous oxide (N2O) and methane (CH4). Argus is unique in its small size making it well suited for limited payload atmospheric research platforms. Argus employs second harmonic spectroscopy using tunable lead-salt diode lasers emitting in the mid-infrared. We first explain the Argus design philosophy followed by detailed descriptions of the instrument's optical, mechanical, and thermal sub-systems. Argus employs an in-flight calibration system providing real time calibrations and tightly constrained uncertainty estimates of the returned data. Data analysis is carried out using non-linear least-squares model fits to the acquired second harmonic spectra. A sampling of Argus data acquired on a recent stratospheric research campaign in the Arctic winter is presented.

GABA-mediated Ca2+ signalling in developing rat cerebellar Purkinje neurones

1. Cellular responses to GABA(A) receptor activation were studied in developing cerebellar Purkinje neurones (PNs) in brain slices obtained from 2- to 22-day-old rats. Two-photon fluorescence imaging of fura-2-loaded cells and perforated-patch recordings were used to monitor intracellular Ca2+ transients and to estimate the reversal potential of GABA-induced currents, respectively. 2. During the 1st postnatal week, focal application of GABA or the GABA(A) receptor agonist muscimol evoked transient increases in [Ca2+]i in immature PNs. These Ca2+ transients were reversibly abolished by the GABA(A) receptor antagonist bicuculline and by Ni2+, a blocker of voltage-activated Ca2+ channels. 3. Perforated-patch recordings were used to measure the reversal potential of GABA-evoked currents (E(GABA)) at different stages of development. It was found that E(GABA) was about -44 mV at postnatal day 3 (P3), it shifted to gradually more negative values during the 1st week and finally equilibrated at -87 mV at around the end of the 2nd postnatal week. This transition was well described by a sigmoidal function. The largest change in E(GABA) was -7 mV x day(-1), which occurred at around P6. 4. The transition in GABA-mediated signalling occurs during a period in which striking changes in PN morphology and synaptic connectivity are known to take place. Since such changes were shown to be Ca2+ dependent, we propose that GABA-evoked Ca2+ signalling is one of the critical determinants for the normal development of cerebellar PNs.

Oral mucositis and the clinical and economic outcomes of hematopoietic stem-cell transplantation

PURPOSE

To explore the relationship between oral mucositis and selected clinical and economic outcomes in blood and marrow transplant patients.

PATIENTS AND METHODS

Subjects consisted of 92 transplant patients from eight centers who participated in a multinational pilot study of a new oral mucositis scoring system (Oral Mucositis Assessment Scale [OMAS]). In the pilot study, patients were evaluated for erythema and ulceration/pseudomembrane formation beginning on the first day of conditioning and continuing for 28 days. We examined the relationship between patients' peak OMAS scores and days with fever (body temperature > 38.0 degrees C), the occurrence of significant infection, days of total parenteral nutrition (TPN), and days of injectable narcotic therapy (all over 28 days), days in hospital (over 60 days), total hospital charges for the index admission, and vital status at 100 days.

RESULTS

Patients' peak OMAS scores spanned the full range of possible values (0 to 5) and were significantly (P <.05) correlated with all of the outcomes of interest except days with fever (P =.21). In analyses controlling for type of graft (autologous v allogeneic) and study center, a 1-point increase in peak OMAS score was associated with (1) 1.0 additional day with fever (P <.01), (2) a 2.1-fold increase in risk of significant infection (P <.01), (3) 2.7 additional days of TPN (P <.0001), (4) 2.6 additional days of injectable narcotic therapy (P <.0001), (5) 2.6 additional days in hospital (P <.01), (6) $25,405 in additional hospital charges (P <.0001), and (7) a 3.9-fold increase in 100-day mortality risk (P <.01). Mean hospital charges were $42,749 higher among patients with evidence of ulceration compared with those without (P =.06).

CONCLUSION

Oral mucositis is associated with significantly worse clinical and economic outcomes in blood and marrow transplantation.

Large-scale oscillatory calcium waves in the immature cortex

Two-photon imaging of large neuronal networks in cortical slices of newborn rats revealed synchronized oscillations in intracellular Ca2+ concentration. These spontaneous Ca2+ waves usually started in the posterior cortex and propagated slowly (2.1 mm per second) toward its anterior end. Ca2+ waves were associated with field-potential changes and required activation of AMPA and NMDA receptors. Although GABAA receptors were not involved in wave initiation, the developmental transition of GABAergic transmission from depolarizing to hyperpolarizing (around postnatal day 7) stopped the oscillatory activity. Thus we identified a type of large-scale Ca2+ wave that may regulate long-distance wiring in the immature cortex.

NMDA receptor-mediated subthreshold Ca(2+) signals in spines of hippocampal neurons

We have used rapid confocal microscopy to investigate the mechanism of Ca(2+) signals in individual dendritic spines of hippocampal CA1 pyramidal cells. The experiments focused on the signals that occur during single weak synaptic responses that were subthreshold for triggering postsynaptic action potentials. These Ca(2+) signals were not strongly affected by blocking the EPSPs with the AMPA receptor antagonist CNQX. The signals were also not strongly reduced by blocking T-type voltage-gated Ca(2+) channels (VGCCs) with Ni(2+) or by blocking a broad range of VGCCs with intracellular D890. The spine Ca(2+) signals were blocked by NMDA receptor channel (NMDAR) antagonist and had the voltage dependence characteristic of these channels. Neither ryanodine nor cyclopiazonic acid (CPA), substances known to deplete intracellular Ca(2+) stores, substantially reduced the amplitude of synaptically evoked Ca(2+) signals. CPA slowed the recovery phase of Ca(2+) signals in spines produced by synaptic stimulation or by backpropagating action potentials, suggesting a role of intracellular stores in Ca(2+) reuptake. Thus, we find that Ca(2+) release from intracellular stores is not required to produce spine Ca(2+) signals. We conclude that synaptic Ca(2+) signals in spines are primarily caused by Ca(2+) entry through NMDARs. Although these channels are largely blocked by Mg(2+) at voltages near the resting potential, they can nevertheless produce significant Ca(2+) elevation. The resulting Ca(2+) signals are an integral component of individual evoked or spontaneous synaptic events and may be important in the maintenance of synaptic function.

Two-photon Na+ imaging in spines and fine dendrites of central neurons

Dendritic spines are assumed to be the smallest units of neuronal integration. Because of their miniature size, however, many of their functional properties are still unclear. New insights in spine physiology have been provided by two-photon laser-scanning microscopy which allows fluorescence imaging with high spatial resolution and minimal photodamage. For example, two-photon imaging has been employed successfully for the measurement of activity-induced calcium transients in individual spines. Here, we describe the first application of two-photon imaging to measure Na+ transients in spines and dendrites of CA1 pyramidal neurons in hippocampal slices. Whole-cell patch-clamped neurons were loaded with the Na(+)-indicator dye SBFI (sodium-binding benzofuran-isophthalate). In situ calibration of SBFI fluorescence with ionophores enabled the determination of the actual magnitude of the [Na+]i changes. We found that back-propagating action potentials (APs) evoked Na+ transients throughout the proximal part of the dendritic tree and adjacent spines. The action-potential-induced [Na+]i transients reached values of 4 mM for a train of 20 APs and monotonically decayed with a time constant of several seconds. These results represent the first demonstration of activity-induced Na+ accumulation in spines. Our results demonstrate that two-photon Na+ imaging represents a powerful tool for extending our knowledge on Na+ signaling in fine cellular subcompartments.

Intracranial stenoocclusive disease: double-detector helical CT angiography versus digital subtraction angiography

BACKGROUND AND PURPOSE

To our knowledge, no large-scale studies comparing the accuracy of CT angiography (CTA) to intraarterial digital subtraction angiography (DSA) of intracranial stenosis have been reported. We attempted to determine the diagnostic value of intracranial CT angiography (CTA) of normal vasculature and variants as well as of stenoocclusive disease.

METHODS

One-hundred and twelve patients underwent CTA and intraarterial angiography, and 2205 vascular segments were examined to ascertain presence, visibility, and degree of arterial stenoses (n = 105) as well as anatomic variants. Source, maximum intensity projection (MIP), and MIP-generated multiplanar reformatted (MPR) images were evaluated.

RESULTS

All 55 anatomic variants were identified correctly. Visibility of small-vessel segments was increased from 75% to 83% by using source images. MPR was helpful in differentiating distal vertebral hypoplasia from stenosis and in overcoming artifacts. All 43 occlusive segments were graded correctly (sensitivity = 100%, predictive value = 93.4%) as follows: severely stenotic ([n = 23], sensitivity = 78%, predictive value = 81.8%); moderately stenotic ([n = 36], sensitivity = 61%, predictive value = 84.6%); and mildly stenotic ([n = 3], sensitivity = 66%, predictive value = 28%). Normal segments (n = 2100) had a sensitivity of 99.5%, and CTA evinced a specificity of 99% for detecting stenoocclusive disease. Approximately one-third of wrong assessments were related to the petrous segment of the carotid artery.

CONCLUSION

CTA with double-detector technology and advanced postprocessing algorithms, including MPR, is about as reliable as MRA in depicting the vasculature of the anterior and posterior circulation and in grading intracranial stenoocclusive lesions, with the exception of the petrous segment of the carotid artery. CTA might be superior to MRA in the evaluation of poststenotic low-flow segments.

A new class of synaptic response involving calcium release in dendritic spines

In the classical view, transmission of signals across synapses in the mammalian brain involves changes in the membrane potential of the postsynaptic cell. The use of high-resolution cellular imaging has revealed excitatory synapses at which postsynaptic, transient alterations in calcium ion concentration are tightly associated with electrical responses. Here, by investigating the synapse between parallel glutamatergic fibres and Purkinje cells in the mouse cerebellum, we identify a class of postsynaptic responses that consist of transient increases in dendritic Ca2+ concentration but not changes in somatic membrane potential. Our results indicate that these synaptic Ca2+ transients are mediated by activation of metabotropic glutamate-responsive mGluR1-type receptors and require inositol-1,4,5-trisphosphate-mediated Ca2+ release from intradendritic stores. The new type of synaptic response is restricted to postsynaptic microdomains, which range, depending on the frequency of stimulation, from individual spines to small spinodendritic compartments. Thus, the synaptic Ca2+-release signal may be one of the critical cues that determine the input specificity of long-term depression, a well-established form of activity-dependent plasticity at these synapses.

Factors influencing oral cavity status during high-dose antineoplastic therapy: a secondary data analysis

PURPOSE/OBJECTIVES

To identify factors associated with oral cavity status in patients receiving high-dose antineoplastic therapy.

DESIGN

Descriptive, correlational secondary analysis.

SETTING

Midwestern university oncology special care unit.

SAMPLE

50 males and females, ages 15-69.

METHODS

The Oral Assessment Guide (OAG) was used to assess oral cavity status every shift throughout hospitalization. Additional data were collected by chart audit. Correlations and Cox regression analysis were performed.

MAIN RESEARCH VARIABLES

Oral cavity status, absolute granulocyte count, blood urea nitrogen (BUN), creatinine, mean OAG score during the preparative regimen (prep-OAG), age, and total body irradiation (TBI).

FINDINGS

Elevated BUN and creatinine, higher prep-OAG, older age, and TBI were associated with higher OAG scores. Cox analysis revealed that TBI was predictive of an OAG score > or = 16, and an OAG score > or = 18 was predictive of death by day +20.

CONCLUSIONS

Patients who receive TBI and chemotherapy in combination are most likely to experience severely compromised oral cavity status. Those who are older, have poorer oral status, and have decreased renal function are at increased risk.

IMPLICATIONS FOR NURSING PRACTICE

High-risk patients must be identified early, and oral assessments and care must be given consistently to decrease morbidity and potential mortality.

Importance of the intracellular domain of NR2 subunits for NMDA receptor function in vivo

NMDA receptors, a class of glutamate-gated cation channels with high Ca2+ conductance, mediate fast transmission and plasticity of central excitatory synapses. We show here that gene-targeted mice expressing NMDA receptors without the large intracellular C-terminal domain of any one of three NR2 subunits phenotypically resemble mice made deficient in that particular subunit. Mice expressing the NR2B subunit in a C-terminally truncated form (NR2B(deltaC/deltaC) mice) die perinatally. NR2A(deltaC/deltaC) mice are viable but exhibit impaired synaptic plasticity and contextual memory. These and NR2C(deltaC/deltaC) mice display deficits in motor coordination. C-terminal truncation of NR2 subunits does not interfere with the formation of gateable receptor channels that can be synaptically activated. Thus, the phenotypes of our mutants appear to reflect defective intracellular signaling.

The flaginserter: a simple device for automatically marking events in video recordings

Dynamic imaging of cellular responses often involves the use of standard video components. While these components (cameras, monitors, etc.) are relatively inexpensive and easily available, there is the difficulty of integrating them into experimental set-ups. Especially for video recordings of fast signals that occur in neurobiological preparations (e.g. synaptic responses), there is a critical need for accurate synchronisation of video images with external events, such as extracellular stimulation or intracellular depolarising voltage steps. We developed a circuit that allows such events within the video sequence to be marked by means of a white flag that is inserted into the video image. Depending on the mode of insertion, the time resolution is better than 17 ms or better than 65 micros (i.e. a single video field or video line, respectively). The circuit has been shown to work reliable in combination with video-rate confocal imaging and patch-clamp recordings.

Dendritic signal integration

Recent studies have identified various forms of active dendritic signals that may contribute to neuronal integration. One of the most remarkable findings is the demonstration of highly localized Ca2+ transients that are limited to small dendritic segments and even to single dendritic spines. In addition, through use of the powerful two-photon excitation imaging technique, it has been possible to reveal the existence of dendritic Ca2+ signals under in vivo conditions. Finally, active backpropagation of action potentials into dendrites has been shown to boost dendritic Ca2+ signals supralinearly and, thus, to contribute to the induction of long-term potentiation.

Local dendritic Ca2+ signaling induces cerebellar long-term depression

The coordinated activity of large numbers of adjacent parallel fiber synapses elevate calcium concentration locally in small regions of Purkinje cell dendrites. Such activity has also been reported to produce long-term depression of parallel fiber synaptic transmission. We have examined the relationship between these two events by combining patch clamp measurements of parallel fiber synaptic transmission with confocal microscopic imaging of the local calcium signals. We find that patterns of parallel fiber activity capable of evoking long-term depression invariably cause increases in Purkinje cell calcium concentration that are very spatially restricted. These results suggest that one function of the local dendritic calcium signals is to induce long-term depression of parallel fiber synapses.

Ataxia and altered dendritic calcium signaling in mice carrying a targeted null mutation of the calbindin D28k gene

Intracellular calcium-binding proteins are abundantly expressed in many neuronal populations. Previous evidence suggests that calcium-binding proteins can modulate various neuronal properties, presumably by their action as calcium buffers. The importance of calcium-binding proteins for nervous system function in an intact integrated system is, however, less clear. To investigate the physiological role of a major endogenous calcium-binding protein, calbindin D28k (calbindin) in vivo, we have generated calbindin null mutant mice by gene targeting. Surprisingly, calbindin deficiency does not affect general parameters of development and behavior or the structure of the nervous system at the light microscopic level. Null mutants are, however, severely impaired in tests of motor coordination, suggesting functional deficits in cerebellar pathways. Purkinje neurons, the only efferent of the cerebellar cortex, and inferior olive neurons, the source of the climbing fiber afferent, have previously been shown to express calbindin. Correlated with this unusual type of ataxia, confocal calcium imaging of Purkinje cells in cerebellar slices revealed marked changes of synaptically evoked postsynaptic calcium transients. Their fast, but not their slow, decay component had larger amplitudes in null mutant than in wild-type mice. We conclude that endogenous calbindin is of crucial importance for integrated nervous system function.

Axonal calcium entry during fast 'sodium' action potentials in rat cerebellar Purkinje neurones

1. Using laser-scanning confocal microscopy, fast Ca2+ transients were recorded in individual not yet myelinated axons of Purkinje neurones in cerebellar slices from young rats. Axonal Ca2+ transients could be detected during a single action potential and had progressively larger amplitudes when the number of action potentials was increased. 2. Under voltage-clamp conditions, axonal Ca2+ transients were as large as those observed in dendrites and in the cell body. Axonal Ca2+ transients were completely blocked by 100 nM of the neurotoxin omega-agatoxin IVA, indicating that they were caused by Ca2+ entry through P-type voltage-gated Ca2+ channels. 3. In conclusion, our results demonstrate action potential-mediated Ca2+ entry through voltage-gated Ca2+ channels in axons of cerebellar Purkinje neurones. Experimental evidence indicates that the resulting transient Ca2+ accumulations regulate the frequency of action potentials travelling along the axon.

Localized calcium signalling and neuronal integration in cerebellar Purkinje neurones

The use of high resolution imaging techniques has revealed new forms of dendritic signal integration in neurones. In contrast to electrical signals that have a more widespread influence on the cell, brief Ca2+ transients resulting from synaptic activation are often restricted to a small part of the dendritic tree. In cerebellar Purkinje neurones, different levels of Ca2+ signalling have been observed that may involve the entire neurone or be spatially limited to fine dendritic structures. The Ca2+ signals accompanying subthreshold excitatory postsynaptic potentials resulting from stimulation of the excitatory parallel fibre input can be restricted to regions as small as a spiny dendrite or a single dendritic spine. With the recruitment of increasing numbers of inputs there is a summation of Ca2+ signals in highly restricted regions of the spiny dendrites that is independent of electrical summation at the soma. Of a number of potential sources that could provide the Ca2+ responsible for the postsynaptic changes, Ca2+ entry through voltage-gated Ca2+ channels has received the most support, although other sources like Ca2+ entry through ligand-gated channels and especially Ca2+ release from intracellular stores need to be considered.

Calcium signaling in a narrow somatic submembrane shell during synaptic activity in cerebellar Purkinje neurons

Temporal and spatial changes in the intracellular Ca2+ concentration ([Ca2+]i) were examined in dendrites and somata of rat cerebellar Purkinje neurons by combining whole-cell patch-clamp recording and fast confocal laser-scanning microscopy. In cells loaded via the patch pipette with the high-affinity Ca2+ indicator Calcium Green-1 (Kd approximately 220 nM), a single synaptic climbing fiber response, a so-called complex spike, resulted in a transient elevation of [Ca2+]i that showed distinct differences among various subcellular compartments. With conventional imaging, the Ca2+ signals were prominent in the dendrites and almost absent in the soma. Confocal recordings from the somatic region, however, revealed steep transient increases in [Ca2+]i that were confined to a submembrane shell of 2- to 3-microns thickness. In the central parts of the soma [Ca2+]i increases were much slower and had smaller amplitudes. The kinetics and amplitudes of the changes in [Ca2+]i were analyzed in more detail by using the fast, low-affinity Ca2+ indicator Calcium Green-5N (Kd approximately 17 microM). We found that brief depolarizing pulses produced [Ca2+]i increases in a narrow somatic submembrane shell that resembled those seen in the dendrites. These results provide direct experimental evidence that the surface-to-volume ratio is a critical determinant of the spatiotemporal pattern of Ca2+ signals evoked by synaptic activity in neurons.

Subthreshold synaptic Ca2+ signalling in fine dendrites and spines of cerebellar Purkinje neurons

The conventional view of synaptic integration is that it results from the simple summation of electrical signals produced by each active synapse innervating a given neuron. However, because synaptic action can go beyond the production of postsynaptic electrical signals, to include intracellular biochemical events such as the generation of second messengers, it is possible that synaptic integration could occur at another level. We have considered this possibility by examining changes in the dendritic concentration of the second messenger, calcium, resulting from subthreshold excitatory synaptic activity in cerebellar Purkinje neurons. We report here clear evidence that such non-electrical synaptic integration occurs and that it takes place in restricted dendritic compartments consisting of spines and adjacent fine dendrites.