Caregivers' contributions to heart failure self-care: a systematic review

AIMS

The purpose of this study was to conduct a systematic review answering the following questions: (a) what specific activities do caregivers (CGs) contribute to patients' self-care in heart failure (HF)?; and (b) how mature (or developed) is the science of the CG contribution to self-care?

METHODS

MEDLINE, EMBASE, Cumulative Index of Nursing and Allied Health Literature (CINAHL), the Cochrane Library and ClinicalTrials.gov were searched using the terms heart failure and caregiv* as well as the keywords 'careers', 'family members' and 'lay persons' for studies published between 1948 and September 2012. Inclusion criteria for studies were: informal CGs of adult HF patients-either as dependent/independent variable in quantitative studies or participant in qualitative studies; English language. Exclusion criteria for studies were: formal CGs; pediatric, adult congenital, or devices or transplant CGs; mixed diagnosis; non-empiric reports or reports publishing duplicate results. Each study was abstracted and confirmed by two authors. After CG activities were identified and theoretically categorized, an analysis across studies was conducted.

RESULTS

Forty papers were reviewed from a pool of 283 papers. CGs contribute substantively to HF patients' self-care characterized from concrete (weighing the patient) to interpersonal (providing understanding). Only two studies attempted to quantify the impact of CGs' activities on patients' self-care reporting a positive impact. Our analysis provides evidence for a rapidly developing science that is based largely on observational research.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

To our knowledge, this is the first systematic review to examine CGs' contributions in depth. Informal caregivers play a major role in HF self-care. Longitudinal research is needed to examine the impact of CGs' contributions on patient self-care outcomes.

Development and feasibility testing of decision support for patients who are candidates for a prophylactic implantable defibrillator: a study protocol for a pilot randomized controlled trial

BACKGROUND

Patients, identified to be at risk for but who have never experienced a potentially lethal cardiac arrhythmia, have the option of receiving an implantable cardioverter defibrillator (ICD) as prophylaxis against sudden cardiac death - a primary prevention indication. In Canada, there is no clear framework to support patients' decision-making for these devices. Decision support, using a decision aid, could moderate treatment-related uncertainty and prepare patients to make well-informed decisions. Patient decision aids provide information on treatment options, risks, and benefits, to help patients clarify their values for outcomes of treatment options. The objectives of this research are: 1) develop a decision aid, 2) evaluate the decision aid, and 3) determine the feasibility of conducting a trial.

METHODS/DESIGN

A development panel comprised of the core investigative team, health service researchers, decision science experts, cardiovascular healthcare practitioners, and ICD patient representatives will collaborate to provide input on the content and format of the aid. To generate probabilities to include in the aid, we will synthesize primary prevention ICD evidence. To obtain anonymous input about the facts and content, we will employ a modified Delphi process. To evaluate the draft decision aid will invite ICD patients and their families (n = 30) to rate its acceptability. After we evaluate the aid, to determine the feasibility, we will conduct a feasibility pilot randomized controlled trial (RCT) in new ICD candidates (n = 80). Participants will be randomized to receive a decision aid prior to specialist consultation versus usual care. Results from the pilot RCT will determine the feasibility of research processes; inform sample size calculation, measure decision quality (knowledge, values, decision conflict) and the influence of health related quality of life on decision-making.

DISCUSSION

Our study seeks to develop a decision aid, for patients offered their first ICD for prophylaxis against sudden cardiac death. This paper outlines the background and methods of a pilot randomized trial which will inform a larger multicenter trial. Ultimately, decision support prior to specialist consultation could enhance the decision-making process between patients, physicians, and families, associated with life-prolonging medical devices like the ICD.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01876173.

Abstract 117: Application Of A Delphi Method To Develop A Patient Decision Aid For Implantable Cardioverter Defibrillator Candidates

Background: Development of patient decision aids (PtDA) requires decision making about the facts, risks, and benefits to present to patients. Delphi process methodology has been employed successfully as a consensus-building tool across several disciplines. This work represents the first phase of a Canadian study that is developing a PtDA for prophylactic implantable cardioverter defibrillator (ICD) candidates. Our aim was to engage healthcare providers, ICD stakeholders, and patients in decisions about the content and format of the PtDA, using a modified Delphi process.

Method: Twenty healthcare professionals, 1 stakeholder representative, and 16 people living with ICDs were invited to participate. Our Delphi approach utilized electronic and paper based response systems that included 1) anonymity, 2) iteration, 3) controlled feedback and, 4) statistical group response options. The first Delphi round comprised 39 evidence-based survey items including ICD facts, risks, benefits, and values. A review panel of decision aid experts, cardiovascular researchers, and electrophysiologists selected the content items. Participants completed the survey by rating each category item on a 5-point likert scale from “1= not important” to “5 = extremely important”. A predetermined cut-off of > 75%, wherein participants rated an item as “very important” or higher, guided the selection of items during the two Delphi rounds completed. To provide participants with statistical group responses, the second round participants received the anonymous first round item rankings prior to rating the 11 remaining items.

Results: Twenty-seven participants completed round one of the Delphi (14 ICD patients). Mean (SD) age of ICD patients was 66.8 (7.1) years. The number of years of experience in healthcare reported by non-ICD respondents ranged from 2 to30 years. Of the 39 items included in round one, 14 items were retained ( > 75% agreement), 14 items were removed (<60% agreement), and 11 items proceeded to the second round (60-74% agreement). During the second Delphi round (n=27), 6 of the 11 items that did not reach agreement in round one were retained ( > 75% agreement). Examples from item categories include:

1) Risk items - i ) Lead problems over the long term, ii ) Possible complications during the surgical procedure to insert the ICD.

2) Benefit items- i ) Prevent cardiac arrest from a dangerous heart rhythm, ii ) Assurance that a dangerous heart rhythm can be corrected.

3) Fact, Value & Preferences - i ) What a standard ICD cannot do, ii ) The wish for a natural death, iii ) Driving restrictions if the ICD delivers a shock.

Conclusion: The results from this Delphi survey informed the content that will be incorporated into a PtDA for new ICD candidates. The next phase will include field-testing of the PtDA. Ultimately, the goal is to support quality decision making in ICD candidates.

Abstract 189: Expressing Continuous Cardiovascular Outcome Data in Absolute Terms for use in Patient Treatment Decision Aids: Validation of a Proposed Method

Background: Patient decision aids (DA) supplement advice from health care professionals through provision of information on the likelihood of risks and benefits of treatment options. Ideally, these data are expressed in both visual and written form to communicate absolute risk or benefit (i.e., X/100). However, this well-accepted methodology lends itself to outcomes which are binary only. Valid methods for conversion of continuous outcomes for presentation in DAs are not well-established. The difficulty in converting these outcomes is compounded by the need to extract and pool aggregate standardized score data from multiple published sources to generate a single estimate of treatment effect. Our team was met with this challenge when developing a DA for refractory angina; the main outcome was angina frequency (AF) as measured by the AF subscale of the Seattle Angina Questionnaire. We aimed to develop and test the validity of a proposed method, based on statistical theory, for estimating absolute angina reduction based on AF scores.

Methods: AF summary statistics, M(SD), were extracted from 2 distinct intervention studies for which raw data were accessible. A clinically important difference in AF scores was identified through expert consultation. Based on normal distribution theory, aggregate data from both studies were used to estimate the proportion of those who experienced a clinically significant change in AF. Chi-square comparisons of proportions was then used to determine if these estimates were dissimilar from true numbers reflected in the raw data. We then generated 500,000 simulated datasets using the same AF summary statistics, but with widely varying distribution characteristics (e.g., positive skew). Multiple comparisons of estimates to actual proportions of those experiencing a clinically significant change in AF were generated under simulated scenarios and expressed graphically. The effect of summary statistic on these comparisons was examined by conducting the simulations using both M(SD) and medians and interquartile ranges (IQR).

Results: Overall agreement between estimated and actual proportions of those experiencing a clinically significant change in AF was excellent for the real study data; there were no significant differences (p >0.45), and no difference exceeded 5%. These results remained stable when data were pooled from the 2 studies using meta-analysis. For the simulated data sets, concordance between the estimated and actual proportions was also moderate to good in cases where data were not highly skewed (i.e. skewness <2.5); agreement improved in the context of medians and IQRs.

Conclusion: Our results suggest that standard statistical theory can be used to estimate continuous outcomes in absolute terms with reasonable accuracy for use in DAs; caution is advised if outcomes are expected to be highly skewed in distribution.

Age and mental health predict early device-specific quality of life in patients receiving prophylactic implantable defibrillators

BACKGROUND

Ventricular arrhythmia is a significant cause of sudden death. Implantable cardioverter-defibrillators (ICDs) offer at-risk patients a prophylactic treatment option. This prophylaxis is largely responsible for growth in utilization of ICDs. Identification of factors that may impact device-specific quality of life (QOL) is warranted. The influence of preimplant patient variables on postimplant device-specific QOL is unknown. The study aimed to determine whether preimplant psychosocial, generic health-related quality of life (HRQOL), personality disposition, or demographic factors predicted early postimplant device-specific QOL.

METHODS

A prospective cohort study design was employed in 70 adults receiving an ICD for primary prevention. Preimplant, we measured generic HRQOL, personality disposition, depressive symptoms, age, and sex. The primary outcome was 3-month ICD device-specific QOL as measured by the Florida Patient Acceptance Scale (FPAS). We applied hierarchical multivariate regression analysis.

RESULTS

Mean age was 64.8 ± 9.4 years; 12.9% were women. Most had ischemic heart disease (77%) and a heart failure history (54.3%). Preimplant prevalence of elevated depressive symptoms was 30%. Three months post implant, the mean adjusted FPAS score was 76.8 ± 12.98. Of the variance in FPAS scores, 37% was explained by the independent variables. Younger age and poor preimplant mental HRQOL contributed most to lower FPAS scores.

CONCLUSIONS

Patient support and psychosocial interventions should target younger ICD candidates and those reporting poor preimplant mental HRQOL; these patients may be at risk for poor postimplant device-specific QOL.

Patients' decision making to accept or decline an implantable cardioverter defibrillator for primary prevention of sudden cardiac death

BACKGROUND

Patients are offered implantable defibrillators (ICDs) for the prevention of sudden cardiac death (SCD). However, patients' decision-making process (DMP) of whether or not to accept an ICD has not been explored. We asked patients about their decision making when offered an ICD.

DESIGN/SETTING

A grounded theory methodology was employed. Patients were recruited from three ICD centres. Those who received an ICD underwent interviews the first month after implant. Declining patients had interviews at their convenience. In-depth analysis of transcripts was completed. Identified themes were placed along process pathways in a DMP model and tested.

FINDINGS

Forty-four patients consented to participate (25% women). Thirty-four accepted an ICD and 10 (23%) declined. Ages ranged from 26 to 87 (mean = 65; SD = 12.5). Participants were retired (65%), had ischaemic heart disease (64%) and some post-secondary education (52%). The DMP was triggered when patient's risk for SCD was communicated. The physician's recommendation and a new awareness SCD risk were motivators to accept the ICD. Patient's decision-making approaches fell along a continuum, from active and engaged to passive and indifferent. Patient's approaches were influenced most by the following: (i) trust; (ii) social influences and (iii) health state.

CONCLUSIONS

Health-care providers need to recognize the DMP pathways in which ICD candidacy and SCD risk are understood. The factors that influence a patient's decision warrant discussion pre-implant. It is imperative that patients comprehend the meaning of ICD candidacy to make an informed decision. Participants did not recall alternatives to receiving ICD therapy.

Patients' perspectives on end-of-life issues and implantable cardioverter defibrillators

Increasing numbers of cardiovascular patients are receiving implantable cardioverter defibrillators (ICDs) for primary prevention of sudden cardiac death (SCD). This report examines patients' perspectives on related end-of-life issues. Using a grounded theory approach, audiotaped, semi-structured interviews were undertaken with 30 participants from two ICD referral centres in southwestern Ontario (24 who accepted an ICD and 6 who declined). Interview transcripts, verification with interviewees, researcher memos, published literature, and participant demographics were analyzed using NVivo7. Most participants were male, had comorbidities and an ejection fraction of less than 30 percent, and ranged in age from 26 to 87. Consensus was reached by three research team members on three main themes: quality versus quantity of life, preferred mode of death, and the technical realities of the ICD. The ICD was considered in relation to both quantity and quality of life. Most participants focused on the prevention of SCD, not the implications of the ICD for death by any other cause. Participants advocated for incorporating the ICD into advance care planning. Our findings have implications for the development of advance care plans and education of health professionals.

A comparative study of uncertainty, optimism and anxiety in patients receiving their first implantable defibrillator for primary or secondary prevention of sudden cardiac death

BACKGROUND

Increasingly, patients are receiving implantable cardioverter defibrillators (ICDs) for prevention of sudden cardiac death. ICDs are implanted for primary prevention (patients at risk for ventricular arrhythmia [PP]) and secondary prevention (patients who have had/survived a sustained ventricular arrhythmia or cardiac arrest [SP]). Few prospective studies have examined psychosocial factors associated with these patients.

OBJECTIVES

To determine if patients receiving their first ICD for PP versus SP differed in uncertainty, anxiety, and optimism, before, 1 week, and 1 month after implant.

DESIGN

Prospective, descriptive, correlational pilot.

PARTICIPANTS AND SETTING

Fifteen PP and 15 SP patients receiving their first ICD were enrolled. Mean ages (+/- SD) were 65.7+/-11.3 and 67.9+/-7.7 respectively.

METHODS

Mishel's Uncertainty in Illness Scale (MUIS-C), State-Trait Anxiety Inventory (STAI) and the Life Orientation Test (LOT-R) were taken pre-implant, at the first post-implant visit, and at 1 month. Measures were compared using Student't-tests and ANOVA.

RESULTS

Pre-implant, both groups had moderately high MUIS-C scores (mean+/-SD; PP=67.67+/-13.36; SP=70.27+/-6.80; t=0.67; t(df)=28; p=0.507). LOT-R scores were 15.67+/-3.8 for PP and 16.47+/-3.6 for SP; t=0.59; t(df)=28; p=0.557. Pre-implant state anxiety scores were (mean PP=37.40+/-10.0, SP=37.73+/-13.6; t=0.076; t(df)=28; p=0.940). At 1-month PP patients had significantly lower uncertainty scores than the SP group (mean 62.33+/-4.17 versus 67.87+/-4.61; t=3.45; t(df)=28; p=0.002). A main effect for time, between pre-implant and 1-month, was found for uncertainty (F(2,56)=3.26; p<0.05) and state anxiety (F(2,56)=3.61, p<0.05), where both groups showed lower scores.

CONCLUSION

This study identified moderately high uncertainty in PP and SP patients prior to receiving their ICD. Though uncertainty was high, both groups reported an optimistic disposition and normal anxiety. At 1-month, SP patients had higher uncertainty scores than PP patients. This post-intervention uncertainty among patients who experienced an arrhythmic event warrants attention from nurses caring for ICD patients. Interventions to ameliorate uncertainty should be tailored to consider ICD indication.

Knockout of plasminogen activator inhibitor 1 gene reduces amyloid beta peptide burden in a mouse model of Alzheimer's disease

Accumulation of amyloid beta peptide (Aβ) in the brain is a pathological hallmark of Alzheimer's disease (AD); the underlying mechanism, however, is not well understood. In this study, we show that expression of plasminogen activator inhibitor 1 (PAI-1), a physiological inhibitor of tissue type and urokinase type plasminogen activators (tPA and uPA), increases with age in the brain of wild type and Aβ precursor protein-presenilin 1 (APP/PS1) transgenic mice as well as in AD patients. Most importantly, we show that knocking out the PAI-1 gene dramatically reduces Aβ burden in the brain of APP/PS1 mice but has no effect on the levels of full-length APP, alpha or beta C-terminal fragments. Furthermore, we show that knocking out the PAI-1 gene leads to increases in the activities of tPA and plasmin, and the plasmin activity inversely correlates with the amounts of SDS insoluble Aβ40 and Aβ42. Together, these data suggest that increased PAI-1 expression/activity contributes importantly to Aβ accumulation during aging and in AD probably by inhibiting plasminogen activation and thus Aβ degradation.

Phylogenetic and functional biomakers as indicators of bacterial community responses to mixed-waste contamination

Few studies have demonstrated changes in community structure along a contaminant plume in terms of phylogenetic, functional, and geochemical changes, and such studies are essential to understand how a microbial ecosystem responds to perturbations. Clonal libraries of multiple genes (SSU rDNA, nirK, nirS, amoA, pmoA, and dsrAB) were analyzed from groundwater samples (n = 6) that varied in contaminant levels, and 107 geochemical parameters were measured. Principal components analyses (PCA) were used to compare the relationships among the sites with respect to the biomarker (n = 785 for all sequences) distributions and the geochemical variables. A major portion of the geochemical variance measured among the samples could be accounted for by tetrachloroethene, 99Tc, No3, SO4, Al, and Th. The PCA based on the distribution of unique biomarkers resulted in different groupings compared to the geochemical analysis, but when the SSU rRNA gene libraries were directly compared (deltaC(xy) values) the sites were clustered in a similar fashion compared to geochemical measures. The PCA based upon functional gene distributions each predicted different relationships among the sites, and comparisons of Euclidean distances based upon diversity indices for all functional genes (n = 432) grouped the sites by extreme or intermediate contaminant levels. The data suggested that the sites with low and high perturbations were functionally more similar than sites with intermediate conditions, and perhaps captured the overall community structure better than a single phylogenetic biomarker. Moreover, even though the background site was phylogenetically and geochemically distinct from the acidic sites, the extreme conditions of the acidic samples might be more analogous to the limiting nutrient conditions of the background site. An understanding of microbial community-level responses within an ecological framework would provide better insight for restoration strategies at contaminated field sites.

Changes in bacterial community structure correlate with initial operating conditions of a field-scale denitrifying fluidized bed reactor

High levels of nitrate are present in groundwater migrating from the former waste disposal ponds at the Y-12 National Security Complex in Oak Ridge, TN. A field-scale denitrifying fluidized bed reactor (FBR) was designed, constructed, and operated with ethanol as an electron donor for the removal of nitrate. After inoculation, biofilms developed on the granular activated carbon particles. Changes in the bacterial community of the FBR were evaluated with clone libraries (n = 500 partial sequences) of the small-subunit rRNA gene for samples taken over a 4-month start-up period. Early phases of start-up operation were characterized by a period of selection, followed by low diversity and predominance by Azoarcus-like sequences. Possible explanations were high pH and nutrient limitations. After amelioration of these conditions, diversification increased rapidly, with the appearance of Dechloromonas, Pseudomonas, and Hydrogenophaga sequences. Changes in NO3, SO4, and pH also likely contributed to shifts in community composition. The detection of sulfate-reducing-bacteria-like sequences closely related to Desulfovibrio and Desulfuromonas in the FBR have important implications for downstream applications at the field site.

Neuregulin-1β modulates in vivo entorhinal–hippocampal synaptic transmission in adult rats

Neuregulin-1 (NRG-1) proteins and their erbB receptors are essential for neuronal development during embryogenesis and may contribute importantly to neuronal function in the adult brain. This study tests the hypothesis that NRG-1beta acts as a modulator of synaptic activity in the adult brain, specifically at hippocampal formation synapses. Adult, male Sprague-Dawley rats were anesthetized and a recording electrode with an attached stainless steel microinjector was stereotaxically positioned to record field potentials (fEPSP) in either the dentate gyrus or the cornu ammonis (CA) 1 field of the hippocampus. The entorhinal cortex was continuously stimulated via a paired stainless steel electrode. Microinjection of NRG-1beta significantly increased the slope of the fEPSP in the dentate gyrus in a dose-dependent manner. Compared with a low dose (20 nM), a high dose (100 nM) of NRG-1beta induced a shorter latency response that was of greater magnitude. Responses to NRG-1beta were abolished by pretreatment with a selective, reversible erbB tyrosine kinase inhibitor, PD158780 (100 microM). Further, PD158780 (100 microM) itself significantly decreased the entorhinal-dentate fESPS slope by about 15%. Neither equimolar (100 nM) nor hypermolar (100 microM) sucrose or heat-inactivated NRG-1beta (100 nM) significantly altered the entorhinal-dentate fEPSP slope. In contrast to its effect at the entorhinal-dentate synapse, NRG-1beta (100 nM) depressed, and PD158780 potentiated entorhinal-CA1 synaptic transmission. Thus, in adult rats NRG-1beta potentiates transmission at the entorhinal-dentate synapse but suppresses transmission at the entorhinal-CA1 synapse. These observations indicate that NRG-1 is not only a developmental growth factor, but also modifies synaptic transmission in adult rat brain.

Targeting and functional role of N-RAP, a nebulin-related LIM protein, during myofibril assembly in cultured chick cardiomyocytes

Targeting and functional effects of N-RAP domains were studied by expression as GFP-tagged fusion proteins in cultured embryonic chick cardiomyocytes. GFP-tagged N-RAP was targeted to myofibril precursors, myofibril ends and cell contacts, expression patterns that are similar to endogenous N-RAP. The GFP-tagged N-RAP LIM domain (GFP-N-RAP-LIM) was targeted to the membrane in cells with myofibril precursors and cell-cell contacts. The GFP-tagged super repeats (N-RAP-SR) and the GFP-tagged domain normally found in between the super repeats and the LIM domain (N-RAP-IB) were each observed at sites of myofibril assembly, incorporating into myofibril precursors in a manner similar to full length N-RAP. However, unlike full-length N-RAP, N-RAP-SR and N-RAP-IB were also found in mature myofibrils, associating with the sarcomeric actin filaments and the Z-lines, respectively. N-RAP-IB was also colocalized with α-actinin at cell contacts. Each of the N-RAP constructs could inhibit the formation of mature myofibrils in cultured cardiomyocytes, with the effects of N-RAP-SR and N-RAP-IB depending on the time of transfection. The results show that each region of N-RAP is crucial for myofibril assembly. Combining the targeting and functional effects of N-RAP domains with information in the literature, we propose a new model for initiation of myofibrillogenesis.

ErbB transmembrane tyrosine kinase receptors are differentially expressed throughout the adult rat central nervous system

The neuregulin (NRG) family of growth and differentiation factors and their erbB receptors contribute importantly to the development of the nervous system, but their distribution and function in the adult brain are poorly understood. The present study showed that erbB2, erbB3, and erbB4 transcripts and protein are distributed throughout all areas of adult rat brain. These three receptors were differentially expressed in neurons and glia. Some neurons expressed only a subset of erbB kinases, whereas other neurons expressed all three erbB receptors but sequestered each of these polypeptides into distinct cellular compartments. In synapse-rich regions, erbB immunoreactivity appeared as punctate-, axon-, and/or dendrite-associated staining, suggesting that NRGs are involved in the formation and maintenance of synapses in adult brain. ErbB labeling also was present in neuronal soma, indicating that NRGs act at sites in addition to the synapse. Glia in adult brain also differentially expressed erbB3 and erbB4. Approximately half of the erbB3 labeling in white matter was associated with S100beta+/glial fibrillary acidic protein negative macroglia (i.e., oligodendrocytes or glial fibrillary acidic protein negative astrocytes). In contrast, macroglia in gray matter did not express erbB3. The remaining erbB3 immunoreactivity in white matter and erbB4 glial staining seemed to be associated with microglia. These results showed that erbB receptors are expressed widely in adult rat brain and that each erbB receptor subtype has a distinct distribution. The differential distributions of erbB receptors in neurons and glia and the known functional differences between these kinases suggest that NRGs have distinct effects on these cells. The continued expression of NRGs and their erbB receptors in mature brain also implies that these molecules perform important functions in the brain throughout life.

Attenuation of experimental autoimmune demyelination in complement-deficient mice

The exact mechanisms leading to CNS inflammation and myelin destruction in multiple sclerosis and in its animal model, experimental allergic encephalomyelitis (EAE) remain equivocal. In both multiple sclerosis and EAE, complement activation is thought to play a pivotal role by recruiting inflammatory cells, increasing myelin phagocytosis by macrophages, and exerting direct cytotoxic effects through the deposition of the membrane attack complex on oligodendrocytes. Despite this assumption, attempts to evaluate complement's contribution to autoimmune demyelination in vivo have been limited by the lack of nontoxic and/or nonimmunogenic complement inhibitors. In this report, we used mice deficient in either C3 or factor B to clarify the role of the complement system in an Ab-independent model of EAE. Both types of complement-deficient mice presented with a markedly reduced disease severity. Although induction of EAE led to inflammatory changes in the meninges and perivascular spaces of both wild-type and complement-deficient animals, in both C3(-/-) and factor B(-/-) mice there was little infiltration of the parenchyma by macrophages and T cells. In addition, compared with their wild-type littermates, the CNS of both C3(-/-) and factor B(-/-) mice induced for EAE are protected from demyelination. These results suggest that complement might be a target for the therapeutic treatment of inflammatory demyelinating diseases of the CNS.

Glutamate transporter EAAT2 splice variants occur not only in ALS, but also in AD and controls

OBJECTIVE

To ascertain the specificity of alternatively spliced mRNA variants of the astroglial glutamate transporter EAAT2 for ALS.

BACKGROUND

An important hypothesis for ALS pathogenesis is that motor neuron injury may result from chronically elevated glutamate levels in the CNS. Supporting this idea are reports of decreased glutamate transport in ALS. This in turn has recently been suggested to be due to the presence of aberrant mRNA splice variants for EAAT2 in ALS.

METHODS

Postmortem human brain tissue was obtained from different brain regions of patients with ALS, normal controls (NC), and patients with AD and Lewy body dementia (LB)-neurodegenerative diseases in which motor neurons are unaffected. Brain RNA was analyzed for EAAT2 isoforms using reverse transcription PCR and cDNA cloning/sequencing methods.

RESULTS

Splice variants lacking exons 7 or 9 were present in ALS brain, as previously reported, but were also present in brains from NC, AD, and LB patients. PCR product sequence analyses from non-ALS brain show variant splicing identical to that reported for ALS. Quantitative PCR analysis shows that these isoforms may be somewhat more abundant in ALS than AD, LB, and NC brains.

CONCLUSIONS

EAAT2 mRNA splice variants are found in the brains of NC and AD patients, as in ALS. The authors cannot exclude the possibility that quantitative changes in variant EAAT2 isoforms might relate directly, or indirectly, to ALS pathology. However, the qualitative presence of these "abnormal" EAAT2 splice variants does not appear to be sufficient to explain motor neuron degeneration in ALS.

Myofibrillogenesis and formation of cell contacts mediate the localization of N-RAP in cultured chick cardiomyocytes

The expression of N-RAP was investigated in immuofluorescently stained embryonic chick cardiomyocyte cultures. After 1 day in culture, the cardiomyocytes were spherical and N-RAP, titin, alpha-actinin, and vinculin were all diffusely distributed. As the cardiomyocytes spread and formed myofibrils and cell contacts, N-RAP became localized to distinct areas in the cells. During myofibrillogenesis, N-RAP was found concentrated in premyofibrils. As the premyofibrils transformed into bundles of mature myofibrils, N-RAP became concentrated at the longitundal ends of the cells, and was not found in the mature sarcomeres. At sites of cell-cell contacts, N-RAP was localized to the cell junction even in cells without any significant myofibril formation. As the cell-cell contacts became more extensive and formed structures resembling the intercalated disks found in hearts, N-RAP became even more specifically concentrated at these junctions. The results show that myofibrillogenesis and cell contact formation can each independently target N-RAP to the longitudinal ends of cardiomyocytes.

Expression of JE (monocyte chemoattractant protein-1) is induced by sciatic axotomy in wild type rodents but not in C57BL/Wld(s) mice

Recruitment of hematogenous myelomonocytic cells into injured peripheral nerve is essential for axonal regeneration. The monocyte chemoattractant protein-1 (JE) and melanoma growth stimulatory activity/gro (KC) "immediate early" gene products may be important in this process as these proteins are potent chemoattractants for macrophages and neutrophils, respectively. To test this hypothesis, we examined JE and KC activation in rat sciatic nerve 0-30 days after surgical transection. RT-PCR and in situ hybridization analyses of JE and KC expression demonstrates these mRNAs are present in injured nerve, first being expressed by a cellular subpopulation within the zone of trauma by 1.5 hours after injury. By 16 hours posttransection a subpopulation of JE-positive endoneurial cells is found in the proximal stump and throughout the distal nerve segment, with maximal mRNA accumulation occurring 1 day after injury and expression persisting to 18 days postaxotomy, a period preceding and coincident with macrophage infiltration. In contrast, by 3 days postaxotomy KC expression is markedly diminished, consistent with the limited neutrophilic response to nerve injury. JE expression was also examined in C57BL/Wld(s) mice, which have delayed Wallerian degeneration associated with a failure of macrophage recruitment, and their parental C57BL/6J strain. Although JE mRNA is inducible in sciatic nerve from C57BL/6J mice, these transcripts are undetectable in injured nerve from C57BL/Wld(s) mice. Our findings suggest that activation of the JE locus is at least partially responsible for macrophage invasion of injured peripheral nerve. Furthermore, defective postaxotomy macrophage recruitment in C57BL/Wld(s) mice may involve a failure of JE induction.

Neurotrophin sensitivity of prevertebral and paravertebral rat sympathetic autonomic ganglia

Prevertebral and paravertebral sympathetic autonomic ganglia respond differently to a large number of experimental and clinical insults. The selective involvement of subpopulations of sympathetic neurons may reflect differences in their response to neurotrophic substances. To test this hypothesis, we investigated the response of prevertebral and paravertebral rat sympathetic ganglia to selected neurotrophic substances in vivo and in vitro and identified the ganglionic distribution of neurons expressing high affinity neurotrophin receptor mRNAs. Dissociated cultures of embryonic prevertebral and paravertebral ganglionic neurons showed comparable responses to NGF deprivation and only small differences in their response to rescue with other trophic substances. In situ hybridization studies of adult rat sympathetic ganglia using probes specific for the high-affinity neurotrophin receptor transcripts trks A, B, and C demonstrated that neurons in both prevertebral and paravertebral sympathetic ganglia express predominantly trkA receptors in vivo. In addition, increased tyrosine hydroxylase (TOH) activity was induced only by doses of neurotrophic substances that activate trkA and showed only small differences between neonatal prevertebral and paravertebral ganglia. Although small differences in the sensitivity of pre- and paravertebral sympathetic neurons to various neurotrophins have been identified in our studies, they are unlikely, in isolation, to explain major differences in the sensitivity of these ganglia to neuropathologic processes.

Clear cell neoplasms and pseudoneoplastic lesions of the central nervous system

Mass lesions of the central nervous system (CNS) that may assume a clear cell appearance are diverse in nature. Primary conditions in this category include oligodendroglioma, hemangioblastoma, germinoma (seminoma), clear cell and chordoid meningioma, pleomorphic xanthoastrocytoma, and lipid-rich glioblastoma. These proliferations usually can be identified by attention to clinical presentation, topographic location, radiographic details, and histological nuances. Occasionally, however, electron microscopy or immunohistological analysis may be necessary. A recommended panel of reagents for the evaluation of clear cell primary CNS lesions include antibodies to glial fibrillary acidic proteins, S-100 protein, epithelial membrane antigen, vimentin, keratins, placental-like alkaline phosphatase, and synaptophysin. This article reviews the salient clinicopathologic attributes of such proliferations, elaborates a practical approach to their diagnosis, and discusses important differential diagnostic considerations. The latter include malformative lesions, infarcts, inflammatory conditions, and secondary lymphomas, carcinomas, and melanomas.

Decay of calcium transients after electrical stimulation in rat fast- and slow-twitch skeletal muscle fibres

1. Calcium transients were calculated from fura-2 fluorescence signals (corrected for kinetic delays in the Ca(2+)-fura-2 reaction) from single rat skeletal muscle fibres, either fully dissociated from the fast-twitch flexor digitorum brevis (FDB) muscle or in small bundles from the slow-twitch soleus muscle. Fibres or bundles were embedded in agarose gel to inhibit movement and stimulated by single or trains of 1-2 ms electrical pulses (100 Hz, 2-400 ms train duration). 2. The rate constant of decay of [Ca2+] determined from single-exponential fits to the final decay phase of [Ca2+] after a single action potential was considerably faster in FDB fibres than in soleus fibres. As the stimulation duration increased, the rate constant of [Ca2+] decay decreased for both the FDB and soleus fibres, but the effect was greater in FDB than in soleus fibres. 3. Using the magnitude of the decline in the rate constant of [Ca2+] decay with increasing stimulation duration as an index of relative contribution of the saturable Ca2+ binding sites on parvalbumin, subpopulations termed 'high', 'medium' and 'low', referring to estimated parvalbumin content, were determined within each group of FDB and soleus fibres. In fibres assigned to the 'high' and 'medium' groups, parvalbumin was the major contributor (50-73%) to the [Ca2+] decay rate constant after a single action potential. In fibres in the 'low' group, parvalbumin contributed only 0-28% to the rate constant of [Ca2+] decay. 4. Fluorescence recordings using mag-fura-2, a lower-affinity Ca2+ indicator expected to be in equilibrium with myoplasmic Ca2+, gave similar values for both the [Ca2+] decay rate constant after a single action potential and the decrease in this rate constant with increased stimulation duration, as found for the fura-2 [Ca2+] transients from FDB and soleus fibres. Thus, the observed differences in decay rate of Ca2+ were not introduced by kinetic correction of the fura-2 recordings, but are attributed to differences in the Ca2+ binding and transport properties of fast- and slow-twitch mammalian fibres.

Calcium transients and calcium homeostasis in adult mouse fast-twitch skeletal muscle fibers in culture

Skeletal muscle fibers enzymatically dissociated from adult mouse flexor digitorum brevis muscles were maintained in culture for up to 8 days. After various times in culture, fibers were loaded with fura 2, and Ca2+ transients for trains of 1, 5, and 10 action potentials (100 Hz) triggered by external electrical stimulation were calculated from fluorescence ratio records corrected for noninstantaneous reaction of fura 2 with Ca2+. The decay rate constants of Ca2+ transients decreased with increasing stimulation duration, indicating a slowing of the Ca(2+)-removal properties with increased stimulation duration. After 6 days in culture, Ca2+ decay rate constants decreased dramatically for all stimulation durations and the differences in decay rate constants among 1, 5, and 10 pulses became smaller. Intracellular parvalbumin content measured by single-fiber immunofluorescence decreased with time in culture in parallel with the decrease in the decay rate constant of Ca2+ transients. Our results suggest that there is a correlation between parvalbumin content and the decay rate constant of the Ca2+ transient.