Impact of circadian time of dosing on cardiomyocyte-autonomous effects of glucocorticoids

OBJECTIVE

Mitochondrial capacity is critical to adapt the high energy demand of the heart to circadian oscillations and diseased states. Glucocorticoids regulate the circadian cycle of energy metabolism, but little is known about how circadian timing of exogenous glucocorticoid dosing directly regulates heart metabolism through cardiomyocyte-autonomous mechanisms. While chronic once-daily intake of glucocorticoids promotes metabolic stress and heart failure, we recently discovered that intermittent once-weekly dosing of exogenous glucocorticoids promoted muscle metabolism in normal and obese skeletal muscle. However, the effects of glucocorticoid intermittence on heart metabolism and heart failure remain unknown. Here we investigated the extent to which circadian time of dosing regulates the effects of the glucocorticoid prednisone in heart metabolism and function in conditions of single pulse or chronic intermittent dosing.

METHODS AND RESULTS

In WT mice, we found that prednisone improved cardiac content of NAD+ and ATP with light-phase dosing (ZT0), while the effects were blocked by dark-phase dosing (ZT12). The drug effects on mitochondrial function were cardiomyocyte-autonomous, as shown by inducible cardiomyocyte-restricted glucocorticoid receptor (GR) ablation, and depended on an intact cardiomyocyte clock, as shown by inducible cardiomyocyte-restricted ablation of Brain and Muscle ARNT-like 1 (BMAL1). Conjugating time-of-dosing with chronic intermittence, we found that once-weekly prednisone improved metabolism and function in heart after myocardial injury dependent on circadian time of intake, i.e. with light-phase but not dark-phase dosing.

CONCLUSIONS

Our study identifies cardiac-autonomous mechanisms through which circadian-specific intermittent dosing reconverts glucocorticoid drugs to metabolic boosters for the heart.

Refined CLARITY-Based Tissue Clearing for Three-Dimensional Fibroblast Organization in Healthy and Injured Mouse Hearts

Cardiovascular disease is the most prevalent cause of mortality worldwide and is often marked by heightened cardiac fibrosis that can lead to increased ventricular stiffness with altered cardiac function. This increase in cardiac ventricular fibrosis is due to activation of resident fibroblasts, although how these cells operate within the 3-dimensional (3-D) heart, at baseline or after activation, is not well understood. To examine how fibroblasts contribute to heart disease and their dynamics in the 3-D heart, a refined CLARITY-based tissue clearing and imaging method was developed that shows fluorescently labeled cardiac fibroblasts within the entire mouse heart. Tissue resident fibroblasts were genetically labeled using Rosa26-loxP-eGFP florescent reporter mice crossed with the cardiac fibroblast expressing Tcf21-MerCreMer knock-in line. This technique was used to observe fibroblast localization dynamics throughout the entire adult left ventricle in healthy mice and in fibrotic mouse models of heart disease. Interestingly, in one injury model, unique patterns of cardiac fibroblasts were observed in the injured mouse heart that followed bands of wrapped fibers in the contractile direction. In ischemic injury models, fibroblast death occurred, followed by repopulation from the infarct border zone. Collectively, this refined cardiac tissue clarifying technique and digitized imaging system allows for 3-D visualization of cardiac fibroblasts in the heart without the limitations of antibody penetration failure or previous issues surrounding lost fluorescence due to tissue processing.

A224 THE MANITOBA LIVING WITH IBD STUDY: MEDICATION ADHERENCE AND MARS-5 VALIDATION

Background

Medication non-adherence in IBD has previously been reported to be quite variable, ranging from 7 to 73%, and is considered to be an important contributor to disease flares. While there is currently no gold standard for medication adherence reporting in IBD, the Medication Adherence Reporting Scale 5 (MARS-5) has frequently been used in this population, but never validated.

Aims

This study aimed to analyze medication adherence rates in a cohort of persons with IBD in Manitoba, report predictors of medication non-adherence on self-reported symptoms, and validate the MARS-5 as a medication adherence tool.

Methods

55 subjects were prospectively followed with biweekly online surveys in the Manitoba Living with IBD Study. Subjects not taking any medications for IBD or only taking as needed, missing adherence data and those lost to follow-up were excluded, leaving 112 subjects. Descriptive data on demographics, surgeries, IBD medications, medication adherence, and measures of disease activity utilizing IBDSI-SF scores were collected. Mean annual medication adherence percentage, IBDSI-SF(>14=active for Crohn’s,>13=active for UC) and MARS-5 scores were calculated. Logistic regression analysis was performed to determine variables associated with medication adherence and to validate the MARS-5.

Results

Mean age was 42.9 years (SD 12.8), with 71.4% being female. Crohn’s disease (CD) was diagnosed in 67.9%, with 37.5% having undergone at least one abdominal surgery. 70.5% of patients were on 2 or more IBD medications. Mean IBDSI score was 15.5 and mean MARS-5 score was 22.5. 20 (17.9%) patients reported a mean adherence of <90% across all medications- 18 were oral medication users, 1 was on an infusion biologic and 1 on subcutaneous adalimumab. 10 (9.8%) had adherence <80%, all of which were to oral medications. Multivariate regression analysis revealed only a diagnosis of Crohn’s disease (OR 4.62; 95% CI 1.37–15.7; p=0.014) to be a predictor of adherence. Disease activity as defined by IBDSI (OR 0.43, 95% CI 0.13–1.45; p=0.139) and fecal calprotectin >250ug/L (OR 1.04, 95% CI 0.35–3.11; p=0.724), age >55 (OR 2.37, 95% CI 0.65–8.65; p=0.476), female sex (OR 0.38, 95% CI 0.097–1.52; p=0.150) and stress (OR 0.67, 95% CI 0.19–2.32; p=0.498) were not shown to be predictors. MARS-5 was compared to percentage adherence, showing moderate correlation (Pearson r=0.46). Logistic regression analysis showed each additional MARS-5 point was associated with a 1.7 times greater odds of >90% adherence.

Conclusions

We report a highly adherent Manitoba IBD cohort. A diagnosis of CD was the only predicitor of adherence. MARS-5 showed moderate correlation with mean percentage adherence values, suggesting it is a valid assessment tool for determining medication adherence in an IBD population.

Funding Agencies

None

Effective clinical supervision of allied health professionals: a mixed methods study

BACKGROUND

Clinical supervision is recommended for allied health professionals for the purpose of supporting them in their professional role, continued professional development and ensuring patient safety and high quality care. The aim of this mixed methods study was to explore allied health professionals' perceptions about the aspects of clinical supervision that can facilitate effective clinical supervision.

METHODS

Individual semi-structured interviews were conducted on a purposive sample of 38 allied health professionals working in a metropolitan public hospital. Qualitative analysis was completed using an interpretive description approach. To enable triangulation of qualitative data, a quantitative descriptive survey of clinical supervision effectiveness was also conducted using the Manchester Clinical Supervision Scale (MCSS-26).

RESULTS

Three main themes emerged from qualitative analysis: Allied health professionals reported that clinical supervision was most effective when their professional development was the focus of clinical supervision; the supervisor possessed the skills and attributes required to facilitate a constructive supervisory relationship; and the organisation provided an environment that facilitated this relationship together with their own professional development. Three subthemes also emerged within each of the main themes: the importance of the supervisory relationship; prioritisation of clinical supervision relative to other professional duties; and flexibility of supervision models, processes and approaches to clinical supervision. The mean MCSS-26 score was 79.2 (95%CI 73.7 to 84.3) with scores ranging from 44 to 100. MCSS-26 results converged with the qualitative findings with participants reporting an overall positive experience with clinical supervision.

CONCLUSIONS

The factors identified by allied health professionals that influenced the effectiveness of their clinical supervision were mostly consistent among the professions. However, allied health professionals reported using models of clinical supervision that best suited their profession's role and learning style. This highlighted the need for flexible approaches to allied health clinical supervision that should be reflected in clinical supervision policies and guidelines. Many of the identified factors that influence the effectiveness of clinical supervision of allied health professionals can be influenced by health organisations.

Abstract 546: Exploring MCUb Function in the Heart and Its Role in Ischemia Reperfusion Injury

Mitochondrial calcium alterations can promote oxidative metabolism to match increasing functional demands during stress stimulation. However, mitochondrial calcium overload-induced cell death contributes to the pathogenesis of several cardiac disorders including ischemia reperfusion injury. The mitochondrial calcium uniporter (MCU) complex is the only identified transporter that permits rapid calcium uptake into mitochondria. While the biological function of the MCU pore-forming subunit has been annotated, much less is known about the MCUb protein, a high similarity paralog that is part of the greater MCU complex. The goal of our study was to investigate the biological function of MCUb, its role in mitochondrial calcium uptake, and its contribution to the pathogenesis of ischemia reperfusion injury in the heart. To address these questions, we generated both MCUb overexpressing mice as well as MCUb null mice.

We observed that the cardiac-specific overexpression of MCUb inhibited mitochondrial calcium uptake, although basal mitochondrial calcium levels remained unchanged. Genetic ablation of MCUb, conversely, did not influence mitochondrial calcium uptake in the heart. MCUb null mice did not have differences in cardiac function by echocardiography, nor were tissue histological changes observed. This lack of an overt phenotype in MCUb null mice may be attributable to very low or even absent expression in the heart at baseline.

However, induction of MCUb protein was observed in the hearts of mice subjected to ischemia reperfusion injury. Thus, mice were challenged with one-hour ischemia followed by 24-hour reperfusion and the ischemic area/area at risk was analyzed. Deletion of MCUb did not change the initial infarct size of the heart. However, MCUb null mice showed decreased fractional shortening 4-weeks after the ischemic injury. Gravimetric analysis as well as histological examination further supported the conclusion that MCUb deletion exacerbated damage in the heart after ischemia reperfusion injury. We are currently investigating the underlying mechanisms of this greater functional deficit.

Abstract 407: Divergent Functions of Thrombospondin Genes in Mammals

Thrombospondin (Thbs) proteins are multidomain, matricellular proteins comprised of 5 genes that each share similar domains and have been largely ascribed the same functional characteristics. The Thbs protein family is divided in 2 subgroups based on multimerization as trimers, (group A: Thbs1 and 2), or as pentamers (group B: Thbs3, 4 and 5). Thbs proteins modulate various aspects of cell- matrix interactions. Thbs1 and 2 can also alter angiogenesis and modulate MMP- as well as TGF beta activity. More recently, we have shown that they can also serve an intracellular chaperone function along the secretory pathway in response to ER stress (Lynch et. al. Cell 2012). The overall aim of this study is to functionally compare the two Thbs subgroups and elucidate their involvement in cardiac homeostasis and disease. Hence we analyzed gain and loss of function mouse models for Thbs1 as a representative of group A and Thbs3 for group B. Our overall conclusion was that Thbs4 serves a protective function in the heart while Thbs1 and Thbs3 are either overtly maladaptive or they predispose to worsening heart disease with injury stimulus. Taken together, this is the first study comparing Thbs subfamilies, unraveling previously unrecognized functions of Thbs1 and 3 in the mammalian heart, which appears to oppose the protective function of Thbs4.

A comparison of the gut microbiome between long-term users and non-users of proton pump inhibitors

BACKGROUND

Proton pump inhibitor (PPI) use is associated with an increased risk of Clostridium difficile infection (CDI), though the mechanism is unclear. PPI induced alterations to the gut microbiome may facilitate the emergence of CDI, though the effects of PPIs on gut microbiota are not well characterised. [Correction added on 10 March 2016, after first online publication: microflora has been changed to microbiota throughout the article.]

AIM

To compare the faecal microbiomes of long-term PPI users to those with no history of PPI use.

METHODS

We used a population-based database to identify individuals with ≥5 years of continuous PPI use along with non-PPI using controls. Stool samples were subjected to microbiological analysis, with hierarchical clustering at genus level, along with alpha and beta diversity measures comparing the two groups. Metadata was accounted for using quantile regression to eliminate potential confounding variables in taxonomic abundance comparisons.

RESULTS

Sixty-one subjects (32 PPI, 29 controls) were analysed. While no significant differences in alpha diversity were found between the PPI users and controls, a moderate shift of the PPI users away from the non-PPI user cluster in the beta diversity was observed. After controlling for pertinent confounders, we discovered a decrease in Bacteroidetes and an increase in Firmicutes at the phylum level. We also performed species classifications and found Holdemania filiformis and Pseudoflavonifractor capillosus to be increased and decreased in the PPI cohort, respectively.

CONCLUSIONS

Long-term PPIs use has an effect on the gut microbiome. The alteration in the ratio of Firmicutes to Bacteroidetes may pre-dispose to the development of CDI.

Abstract 380: Resident Cardiac Fibroblasts Give Rise to Periostin+ Myofibroblasts Which are the Primary Mediators of Cardiac Fibrosis

Resident cardiac fibroblasts (CFs) are potential therapeutic targets in treating or preventing heart failure since they play a critical role in cardiac remodeling and fibrosis after injury or with prolonged stress stimulation. Heterogeneity among activated fibroblasts within the heart has been noted by a number of previous studies in the literature. In addition to resident CFs, many cell types such as endothelial, perivascular and bone marrow cells have been suggested to go through a mesenchymal transition and acquire a myofibroblast-like phenotype during disease conditions. Hence, the cellular origin of the activated myofibroblast within the heart remains uncertain, in part because of a lack in reliable genetic strategies to define cellular lineage. Recent studies suggest that epicardial precursor cells expressing transcription factor 21 (Tcf21) give rise to resident CFs in the adult heart. In addition, the secreted matricellular protein periostin (Postn), appears to be expressed only within activated fibroblasts (myofibroblasts) within the heart. Here we used Tcf21-MerCreMer (Tcf21MCM) knockin mice and Postn-MerCreMer (PostnMCM) knock-in (KI) mice to lineage trace resident CFs and myofibroblasts with injury stimulation. To account for other potential cellular lineages giving rise to fibroblasts in the heart we also performed lineage tracing with the mouse genetic models including LysM-Cre (macrophage), ckit-Cre (bone marrow), Tie2CreERT2 (endothelial) and Myh11-CreERT2 (smooth muscle) in conjunction ROSA26 (R26) locus based loxP inactivated reporter alleles. Results of this study indicate that the Tcf21+ resident CFs are the predominant source for the activated periostin+ MFs which are the key mediators of extracellular matrix (ECM) production and ECM stability in heart whereas the contribution of other lineages to MFs are minimal. Additionally, we have performed single cell RNA sequencing on TCF21+ and Postn+ isolated CFs pre and post myocardial injury in order to define the fibroblast lineage itself at greater molecular depth.

Abstract 74: The Role of Fibroblast-specific Canonical Tgfβ Signaling in Cardiac Fibrosis

Heart failure is a progressive disease characterized by cardiomyocyte loss, interstitial fibrosis, and chamber remodeling. During physiological conditions cardiac fibroblasts contribute to the homeostatic maintenance of myocardial structure as well as the maintenance of biochemical, mechanical and electrical properties of the heart. Injury and/or cytokine stimulation activate fibroblasts which transdifferentiate into myofibroblasts. These newly formed cells secrete extracellular matrix (ECM) for wound healing and tissue remodeling through their contractile activity. Fibrosis mediated by these cells can initially be a beneficial response that acutely scarifies areas after an infarct to prevent wall rupture. However, during chronic disease states such as heart failure, persistent recruitment and activation of fibroblasts leads to excessive deposition of ECM that results in stiffening and pathological remodeling of the ventricles. During chronic heart disease, cardiomyocytes, immune cells and fibroblasts secrete the cytokine transforming growth factor-TGFβ, which activates fibroblasts and promotes their conversion to myofibroblasts. Manipulation of TGFβ by losartan, which antagonizes angiotensin II (AngII) and aspects of TGFβ signaling, has shown some anti-fibrotic effects in cardiovascular remodeling. Also deletion of Tgfbr1 (type I TGFβ receptor) in cardiomyocytes or a TGFβ blocking antibody reduced the fibrotic response after pressure overload. However heart failure was not improved because deleterious TGFβ signaling in fibroblasts persisted. We therefore utilized a novel fibroblast-specific inducible Cre-expressing mouse line (Periostin-MerCreMer) to examine the canonical (Smad2/3) TGFβ signaling within fibroblasts to determine how these cells and their activation mediate disease in heart failure. Our data indicate that fibroblast-specific deletion of Smad3 but not Smad2 was sufficient to significantly inhibit myocardial fibrosis. Smad2/3 double nulls were also generated and analyzed, as were TGFBR1 and TGFBR2 loxp targeted mice, also crossed with the Postn-MerCreMer knockin allele to achieve specificity in activated fibroblasts.

Quantitative myocardial perfusion in mice based on the signal intensity of flow sensitized CMR

BACKGROUND

In the conventional approach to arterial spin labeling in the rodent heart, the relative difference in the apparent T(1) relaxation times corresponding to selective and non-selective inversion is related to perfusion via a two compartment model of tissue. But accurate determination of T(1) in small animal hearts is difficult and prone to errors due to long scan times and high heart rates. In this study we introduce the theoretical frame work for an alternative method (SI-method) based purely on the signal intensity of slice-select and non-select inversion recovery images at a single inversion time at short repetition time.

METHODS

A modified Bloch equation was solved to derive perfusion as a function of signal intensity of flow sensitized segmented gradient echo acquisitions. A two compartment fast exchanging model of tissue was assumed. To test the new technique first it was implemented on a flow phantom and then it was compared with the conventional T(1) method in an in vivo study of healthy C57BL/6 mice (n=12). Finally the SI-method was used in comparison to a Late Gadolinium Enhanced (LGE) method to qualitatively and quantitatively assess perfusion deficits in an ischemia-reperfusion mouse model (n=4).

RESULTS

The myocardial perfusion of healthy mice obtained by the SI-method, 5.6 ± 0.5 ml/g/min, (mean ± standard deviation) was similar (p=0.38) to that obtained by the conventional method, 5.6 ± 0.3 ml/g/min. The variance in perfusion within the left ventricle was less for the SI-method than that for the conventional method (p<0.0001). The mean percentage standard deviation among repeated measures was 3.6%. The LGE regions of the ischemia reperfusion model were matched with regions of hypo-perfusion in the perfusion map. The average perfusion in the hypo perfused region among all four IR mice was 1.2 ± 0.9 ml/g/min and that of the remote region was 4.4 ± 1.2 ml/g/min.

CONCLUSIONS

The proposed signal intensity based ASL method with a segmented acquisition scheme allows accurate high resolution perfusion mapping in small animals. It's short scan time, high reproducibility and ease of post process makes it a robust alternative to the conventional ASL technique that relies on T(1) measurements.

Lipophilic prodrugs of FR900098 are antimicrobial against Francisella novicida in vivo and in vitro and show GlpT independent efficacy

Bacteria, plants, and algae produce isoprenoids through the methylerythritol phosphate (MEP) pathway, an attractive pathway for antimicrobial drug development as it is present in prokaryotes and some lower eukaryotes but absent from human cells. The first committed step of the MEP pathway is catalyzed by 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR/MEP synthase). MEP pathway genes have been identified in many biothreat agents, including Francisella, Brucella, Bacillus, Burkholderia, and Yersinia. The importance of the MEP pathway to Francisella is demonstrated by the fact that MEP pathway mutations are lethal. We have previously established that fosmidomycin inhibits purified MEP synthase (DXR) from F. tularensis LVS. FR900098, the acetyl derivative of fosmidomycin, was found to inhibit the activity of purified DXR from F. tularensis LVS (IC₅₀ = 230 nM). Fosmidomycin and FR900098 are effective against purified DXR from Mycobacterium tuberculosis as well, but have no effect on whole cells because the compounds are too polar to penetrate the thick cell wall. Fosmidomycin requires the GlpT transporter to enter cells, and this is absent in some pathogens, including M. tuberculosis. In this study, we have identified the GlpT homologs in F. novicida and tested transposon insertion mutants of glpT. We showed that FR900098 also requires GlpT for full activity against F. novicida. Thus, we synthesized several FR900098 prodrugs that have lipophilic groups to facilitate their passage through the bacterial cell wall and bypass the requirement for the GlpT transporter. One compound, that we termed “compound 1,” was found to have GlpT-independent antimicrobial activity. We tested the ability of this best performing prodrug to inhibit F. novicida intracellular infection of eukaryotic cell lines and the caterpillar Galleria mellonella as an in vivo infection model. As a lipophilic GlpT-independent DXR inhibitor, compound 1 has the potential to be a broad-spectrum antibiotic, and should be effective against most MEP-dependent organisms.

Genetic deletion of myostatin from the heart prevents skeletal muscle atrophy in heart failure

BACKGROUND

Cardiac cachexia is characterized by an exaggerated loss of skeletal muscle, weakness, and exercise intolerance, although the cause of these effects remains unknown. Here, we hypothesized that the heart functions as an endocrine organ in promoting systemic cachexia by secreting peptide factors such as myostatin. Myostatin is a cytokine of the transforming growth factor-beta superfamily that is known to control muscle wasting.

METHODS AND RESULTS

We used a Cre/loxP system to ablate myostatin (Mstn gene) expression in a cell type-specific manner. As expected, elimination of Mstn selectively in skeletal muscle with a myosin light chain 1f (MLC1f)-cre allele induced robust hypertrophy in all skeletal muscle. However, heart-specific deletion of Mstn with an Nkx2.5-cre allele did not alter baseline heart size or secondarily affect skeletal muscle size, but the characteristic wasting and atrophy of skeletal muscle that typify heart failure were not observed in these heart-specific null mice, indicating that myocardial myostatin expression controls muscle atrophy in heart failure. Indeed, myostatin levels in the plasma were significantly increased in wild-type mice subjected to pressure overload-induced cardiac hypertrophy but not in Mstn heart-specific deleted mice. Moreover, cardiac-specific overexpression of myostatin, which increased circulating levels of myostatin by 3- to 4-fold, caused a reduction in weight of the quadriceps, gastrocnemius, soleus, and even the heart itself. Finally, to investigate myostatin as a potential therapeutic target for the treatment of muscle wasting in heart failure, we infused a myostatin blocking antibody (JA-16), which promoted greater maintenance of muscle mass in heart failure.

CONCLUSIONS

Myostatin released from cardiomyocytes induces skeletal muscle wasting in heart failure. Targeted inhibition of myostatin in cardiac cachexia might be a therapeutic option in the future.

Plasma membrane Ca2+-ATPase isoform 4 antagonizes cardiac hypertrophy in association with calcineurin inhibition in rodents

How Ca2+-dependent signaling effectors are regulated in cardiomyocytes, given the extreme cytoplasmic Ca2+ concentration changes that underlie contraction, remains unknown. Cardiomyocyte plasma membrane Ca2+-ATPase (PMCA) extrudes Ca2+ but has little effect on excitation-contraction coupling, suggesting its potential role in controlling Ca2+-dependent signaling effectors such as calcineurin. We generated cardiac-specific inducible PMCA4b transgenic mice that displayed normal global Ca2+ transient and cellular contraction levels and reduced cardiac hypertrophy following transverse aortic constriction (TAC) or phenylephrine/Ang II infusion, but showed no reduction in exercise-induced hypertrophy. Transgenic mice were protected from decompensation and fibrosis following long-term TAC. The PMCA4b transgene reduced the hypertrophic augmentation associated with transient receptor potential canonical 3 channel overexpression, but not that associated with activated calcineurin. Furthermore, Pmca4 gene-targeted mice showed increased cardiac hypertrophy and heart failure events after TAC. Physical associations between PMCA4b and calcineurin were enhanced by TAC and by agonist stimulation of cultured neonatal cardiomyocytes. PMCA4b reduced calcineurin nuclear factor of activated T cell-luciferase activity after TAC and in cultured neonatal cardiomyocytes after agonist stimulation. PMCA4b overexpression inhibited cultured cardiomyocyte hypertrophy following agonist stimulation, but much less so in a Ca2+ pumping-deficient PMCA4b mutant. Thus, Pmca4b likely reduces the local Ca2+ signals involved in reactive cardiomyocyte hypertrophy via calcineurin regulation.

Cardiac myosin binding protein-C phosphorylation in a {beta}-myosin heavy chain background

BACKGROUND

Cardiac myosin binding protein-C (cMyBP-C) phosphorylation modulates cardiac contractility. When expressed in cMyBP-C-null (cMyBP-C((t/t))) hearts, a cMyBP-C phosphomimetic (cMyBP-C(AllP+)) rescued cardiac dysfunction and protected the hearts from ischemia/reperfusion injury. However, cMyBP-C function may be dependent on the myosin isoform type. Because these replacements were performed in the mouse heart, which contains predominantly alpha-myosin heavy chain (alpha-MyHC), the applicability of the data to humans, whose cardiomyocytes contain predominantly beta-MyHC, is unclear. We determined the effect(s) of cMyBP-C phosphorylation in a beta-MyHC transgenic mouse heart in which >80% of the alpha-MyHC was replaced by beta-MyHC, which is the predominant myosin isoform in human cardiac muscle.

METHODS AND RESULTS

To determine the effects of cMyBP-C phosphorylation in a beta-MyHC background, transgenic mice expressing normal cMyBP-C (cMyBP-C(WT)), nonphosphorylatable cMyBP-C (cMyBP-C(AllP)(-)), or cMyBP-C(AllP+) were bred into the beta-MyHC background (beta). These mice were then crossed into the cMyBP-C((t/t)) background to ensure the absence of endogenous cMyBP-C. cMyBP-C((t/t)/beta) and cMyBP-C(AllP)(-)(:(t/t)/beta) mice died prematurely because of heart failure, confirming that cMyBP-C phosphorylation is essential in the beta-MyHC background. cMyBP-C(AllP+:(t/t)/beta) and cMyBP-C(WT:(t/t)/beta) hearts showed no morbidity and mortality, and cMyBP-C(AllP+:(t/t)/beta) hearts were significantly cardioprotected from ischemia/reperfusion injury.

CONCLUSIONS

cMyBP-C phosphorylation is necessary for basal myocardial function in the beta-MyHC background and can preserve function after ischemia/reperfusion injury. Our studies justify exploration of cMyBP-C phosphorylation as a therapeutic target in the human heart.

Spinal cord magnetic resonance imaging for investigation of nonneurogenic lower urinary tract dysfunction--can the yield be improved?

PURPOSE

Magnetic resonance imaging has been used to detect occult neuropathy in patients with nonneurogenic lower urinary tract dysfunction. There is substantial controversy surrounding the role of this test for lower urinary tract dysfunction. We identified factors associated with positive magnetic resonance imaging to improve patient selection.

MATERIALS AND METHODS

A case-control study was done in all pediatric patients referred to our radiology department for spinal magnetic resonance imaging primarily because of lower urinary tract symptoms between 1995 and 2004. Patients with known neurological disorders or anomalies associated with neurogenic bladder (overt spinal dysraphism, imperforate anus, etc) were excluded. A total of 80 patients with a median age of 6.5 years (range 4 to 17) were identified, of whom 47 (59%) were female. Bivariate analysis was used to evaluate the association of certain variables with positive magnetic resonance imaging findings, including patient age, gender, type of urinary symptoms, fecal soiling, abnormal neuro-orthopedic examination, lumbar cutaneous findings, resistance to medical management and urodynamic findings.

RESULTS

Magnetic resonance imaging revealed spinal abnormalities in 6 cases (7.5%), including intradural arachnoid cyst in 1, sacral dysgenesis in 3, syrinx/hydromyelia in 1 and tethered cord in 1. An abnormal lumbar cutaneous finding was the only variable associated with positive magnetic resonance imaging (Fisher's exact test p = 0.002).

CONCLUSIONS

Spinal magnetic resonance imaging has a low impact in the management of lower urinary tract dysfunction. With proper patient selection the pretest probability of positive magnetic resonance imaging may be increased and, therefore, many unnecessary studies may be avoided. Abnormal cutaneous findings are associated with abnormal magnetic resonance imaging.

Cardiac myosin binding protein C phosphorylation is cardioprotective

Cardiac myosin binding protein C (cMyBP-C) has three phosphorylatable serines at its N terminus (Ser-273, Ser-282, and Ser-302), and the residues' phosphorylation states may alter thick filament structure and function. To examine the effects of cMyBP-C phosphorylation, we generated transgenic mice with cardiac-specific expression of a cMyBP-C in which the three phosphorylation sites were mutated to aspartic acid, mimicking constitutive phosphorylation (cMyBP-C(AllP+)). The allele was bred into a cMyBP-C null background (cMyBP-C((t/t))) to ensure the absence of endogenous dephosphorylated cMyBP-C. cMyBP-C(AllP+) was incorporated normally into the cardiac sarcomere and restored normal cardiac function in the null background. However, subtle changes in sarcomere ultrastructure, characterized by increased distances between the thick filaments, indicated that phosphomimetic cMyBP-C affects thick-thin filament relationships, and yeast two-hybrid data and pull-down studies both showed that charged residues in these positions effectively prevented interaction with the myosin heavy chain. Confirming the physiological relevance of these data, the cMyBP-C(AllP+:(t/t)) hearts were resistant to ischemia-reperfusion injury. These data demonstrate that cMyBP-C phosphorylation functions in maintaining thick filament spacing and structure and can help protect the myocardium from ischemic injury.

Asynchronous burst-suppression in a child with callosal Ki-1 anaplastic large cell lymphoma

A 13-year-old girl with Ki-1 anaplastic large cell lymphoma (Ki-1ALCL) bulky deposits in the brain developed raised intracranial pressure and coma associated with asynchronous burst-suppression following standard dose cranial irradiation. Supportive care, steroids, and chemotherapy resulted in clinical improvement. Burst-suppression coma may be reversible when secondary to tumor, decrease in steroids, or radiation effects; the asynchrony localizes the lesion to cortical interconnections such as the corpus callosum.

Development of an assay for antibodies to Saccharomyces cerevisiae: Easy, cheap and specific for Crohn's disease

OBJECTIVE

To develop a serological test to measure antibodies to Saccharomyces cerevisiae in patients with inflammatory bowel disease.

METHODS

An ELISA to the mannan of S cerevisiae that is commercially available was developed. Sera were tested from randomly chosen sera specimens kept frozen at the University of Manitoba Inflammatory Bowel Disease Clinical and Research Centre, Winnipeg, Manitoba. Clinical diagnoses were kept blinded until the assay results were finalized. One hundred thirty-six sera were tested, including 51 with Crohn's disease, 32 with ulcerative colitis, one with indeterminate colitis and 16 other control subjects. Thirty-six samples were duplicates from patients already studied but were either run on separate days or drawn on different days.

RESULTS

Using a cutoff of 15 binding units as a positive result, Crohn's disease was found to have a sensitivity of 53% but a specificity of 100% compared with ulcerative colitis. Compared with all other diagnoses (including ulcerative colitis), Crohn's disease had a sensitivity of 53% and a specificity of 96%. For patients with Crohn's disease only, those who were anti-S cerevisiae antibody (ASCA) positive (n=27) were significantly more likely to have proximal gastrointestinal disease and significantly less likely to have colonic or inflammatory type disease than those who were ASCA negative (n=24). The direct cost of this assay was $6.00 per positive test, and the total charge was set at $38.15.

CONCLUSIONS

A reasonably inexpensive, easy and reproducible assay to assess for antibodies to S cerevisiae has been developed. Using a cutoff for positivity of 15 binding units, this test had a specificity of 100% for ruling out Crohn's disease and a lower (60%) sensitivity compared with ulcerative colitis. This test could identify a specific phenotype of patients with Crohn's disease as being more likely to have small bowel Crohn's disease and less likely to have colonic (isolated) or inflammatory disease, as opposed to fibrostenotic disease or penetrating disease. The test proved reliable when assaying samples drawn or assayed on different days.

Helicobacter pylori in the Canadian arctic: seroprevalence and detection in community water samples

OBJECTIVE

Many North American arctic communities are characterized by risk markers associated with Helicobacter pylori (H. pylori) infection, including overcrowded housing and inadequate water supply and sanitation systems. Our aim was to determine the seroprevalence of H. pylori infection in two traditional Inuit communities in the central Canadian arctic and to test for the presence of H. pylori, by polymerase chain reaction (PCR), in local water supplies.

METHODS

Samples of venous whole blood from adults and capillary blood from children were collected and analyzed by enzyme immunoassay and Helisal Rapid Test, respectively, for IgG antibody to H. pylori. Antibodies to CagA were detected by enzyme immunoassay, and ABO and Lewis antigens were also determined. Demographic and clinical information were collected by questionnaire. Water samples from each community were tested for H. pylori by PCR.

RESULTS

One hundred-thirty (50.8%) of 256 subjects from the two communities were positive for H. pylori IgG antibodies. Seropositive subjects were more likely to be male, compared with seronegative individuals (p = 0.01). Antibody status did not differ with respect to age, community, alcohol or cigarette use, number of persons per household, gastrointestinal complaints or previous investigations, medications, or presence of blood group O, Lewis a-b+. CagA antibodies were detected in 78 (61.9%) of 126 H. pylori-seropositive subjects tested; however, 41 (35.3%) of 116 H. pylori-seronegative subjects were also CagA positive. Water samples taken from the water delivery truck in Chesterfield Inlet and two lakes near Repulse Bay were positive for H. pylori.

CONCLUSION

The seroprevalence of H. pylori in the study group was higher than rates in southern Canadian populations, but lower than the seroprevalence previously documented in a Canadian subarctic Indian (First Nations) community. The detection of H. pylori in local water supplies may indicate a natural reservoir for the organism or possible contamination from human sewage.

Beta2 integrin/ICAM expression in Crohn's disease

We have previously reported on the expression of the beta2 integrin family of adhesion molecules and their ligands, the ICAM molecules, in the normal human intestine. These molecules likely have a role to play in the inflammatory response and, therefore, were studied in a group of patients with Crohn's disease. A comprehensive study was undertaken in both colon (n = 8) and ileum (n = 10) specimens from 15 patients who underwent surgical resections. Immunohistochemistry was performed for CD18, CD11a, CD11b, CD11c, alphad, ICAM-1, ICAM-2, and ICAM-3. Each of the mucosal, submucosal, muscle, and adventitial layers were scored for expression. Specimens from normal colon (n = 15), normal ileum (n = 6), and ulcerative colitis (n = 7) were used for comparisons. Compared with normal, the expression in the colon mucosa and submucosa in Crohn's disease was increased for all beta2 integrins. Mucosal CD11c expression was significantly greater in Crohn's disease than in ulcerative colitis. In the colon muscle and adventitial layers the expression in Crohn's disease was similar to normal but increased compared with ulcerative colitis. In Crohn's disease ileum, the beta2 integrin mucosal and submucosal expression was similar to normal; however, muscle and adventitial expression was increased, particularly for CD11c. Colon ICAM-1, ICAM-2, and ICAM-3 expression in Crohn's disease was similar to that seen in ulcerative colitis. ICAM-1 was predominantly expressed on endothelium but in the inflammatory bowel diseases was also evident on mucosal mononuclear cells. ICAM-1 and ICAM-2 expression was increased in Crohn's disease colon and ileum compared with normals. This was most notable in ileal mucosa since ICAM-2 is typically absent in normal ileal mucosa. In summary, we are reporting a comprehensive immunohistochemical study of the differential expression of beta2 integrins, including the newly described alphad molecule, and the ICAM molecules in all layers of the colon and ileum from patients with Crohn's disease. The increased expression of these molecules may have implications for therapeutic interventions in Crohn's disease.

Tandem repeat polymorphism and heteroplasmy in the mitochondrial control region of redfishes (Sebastes: Scorpaenidae)

Three species of redfish (Sebastes) share a common pattern of mitochondrial DNA tandem repeat polymorphism and heteroplasmy in the northwest Atlantic Ocean. All three species exhibit 9-17 copies of an approximately 275 base pair (bp) tandem repeat situated within the 3' domain of the control region. Sequence analysis of cloned mtDNA from S. mentella revealed that the tandem array is adjacent to the tRNA(phe) gene, and that the repeat shares 53% identity with the tRNA(phe) gene and part of the 12S rRNA gene. These features, as well as potential secondary structure assumed by the repeat, are consistent with previously proposed models explaining tandem duplications in the 3' end of the control region. In a sample comprising 36 S. fasciatus, 52 S. mentella, and 13 S. marinus taken near Newfoundland, neither the mean number of repeats per fish (12.2-12.7) nor the frequency of heteroplasmy varied significantly among species. A total of 42% of the redfishes were heteroplasmic, bearing either two or three repeat variants (33% and 9%, respectively). The similarity of the frequency distributions of tandem repeat variants in the three species suggests either a common balance between mutation and selection in the three species, or mitochondrial gene flow between them.

Peripheral blood lymphocyte beta 2 integrin and ICAM expression in inflammatory bowel disease

The beta 2 integrin intercellular adhesion molecule (ICAM) adhesion pathway is likely pivotal in the immunopathogenesis of inflammatory bowel disease (IBD). We have undertaken a comprehensive study of peripheral blood lymphocyte (PBL) expression of all beta 2 integrins and ICAMs in patients with IBD using flow cytometry and assessed our data on the basis of IBD diagnosis, disease state of activity, and use of corticosteroids. Blood was collected from patients with Crohn's disease (N = 49), ulcerative colitis (N = 43), and normal control volunteers (N = 15). Mononuclear cells were separated using a Ficoll-Hypaque gradient and prepared for flow cytometry. The data were analyzed for percentage expression, mean fluorescent intensity (MFI) as well as for histogram patterns. The analysis was stratified for disease diagnosis, disease activity level, and for use of prednisone among patients with active disease. There was decreased percentage expression of CD11a, CD18, and ICAM-3 in Crohn's disease and ulcerative colitis compared with normal, but an increased MFI for these molecules among patients with Crohn's disease. Active Crohn's disease showed a greater change in this pattern compared with both inactive disease and active ulcerative colitis. CD11a and CD18 histograms typically had two peaks of expression. The predominance of one peak over the other varied with disease diagnosis and activity. CD11b and alpha d expression patterns were not different in IBD compared with normal. CD11c was not expressed by PBLs and, ICAM-2, typically an endothelial ligand, was expressed on PBLs. There were changes in the expression of beta 2 integrins in IBD, which were more evident in Crohn's disease than ulcerative colitis. We hypothesize that the decreased percentage expression and increased MFI of CD11a, CD18, and ICAM-3 may suggest that cells up-regulate these ligands following activation and are egressing into tissue.

Beta 2-integrin/intercellular adhesion molecule (ICAM) expression in the normal human intestine

The beta 2-integrin family of adhesion molecules and their ligands, the ICAM molecules, probably have an important role to play in the intestinal immune response. To date, any data published regarding the intestinal expression of beta 2-integrins and ICAMs have mostly described only mucosal expression. The presence in the intestine of alpha d, a newly described beta 2-integrin molecule, has not yet been determined. To understand further the expression of these molecules in all layers of the intestine, a comprehensive study was undertaken in both normal colon and normal small intestine specimens from 15 patients (colon n = 15, and ileum n = 6) who underwent surgical resections. Immunohistochemistry was performed for CD18, CD11a, CD11b, CD11c, alpha d, ICAM-1, ICAM-2, and ICAM-3. The colon and small intestine cases were grouped separately and each of the mucosal, submucosal, muscle and adventitial layers were scored for expression. The beta 2-integrin molecules were expressed by mononuclear cells in all layers of the bowel, predominantly in the mucosa and adventitia. CD11a showed the greatest mucosal expression and CD11b showed the greatest adventitial expression. alpha d exhibited expression in all bowel layers, as well, with most intense expression in the mucosa and adventitia. CD11c exhibited the least expression of all alpha subunit molecules. The expression of these alpha-chains at times appeared to be greater than that seen for CD18 (beta 2), raising the possibility of non-beta 2-containing complexes (i.e. alpha-chains associating with an alternate beta-chain). ICAM-1 was expressed on endothelium, particularly in the mucosa and rarely on mucosal mononuclear cells. ICAM-2 was predominantly on submucosal endothelium and rarely expressed in colon mucosa and never expressed in ileal mucosa. ICAM-3 was expressed by mononuclear cells throughout the bowel wall, but also on adventitial endothelium in selected cases. In summary, we are reporting a comprehensive immunohistochemical study of the differential expression of beta 2-integrins, including the newly described alpha d molecule, and the ICAM molecules in all layers of normal human colon and ileum. We raise the possibility that a second beta 2-integrin beta subunit may exist, and we report that ICAM-3 is expressed on endothelium, particularly in the adventitial layer.

The differential expression of a novel intestinal epithelial glycoprotein in various forms of inflammatory bowel disease

A13D8 is a monoclonal IgM antibody that identifies an as yet unknown antigen that is expressed intensely and ubiquitously in enterocytes. Immunohistochemically, it was shown that A13D8 has a granular supranuclear staining pattern in columnar epithelial cells of normal small intestine and the colon. In ulcerative colitis, this staining pattern was retained. However, during active inflammation, staining also was evident in goblet cells. To test whether this feature of goblet cell staining was unique to ulcerative colitis, tissue sections from a variety of colitides were examined. Crohn's disease, infectious colitis, and ischemic colitis had similar staining patterns to that seen with ulcerative colitis. There was significantly more inflammation in the biopsies from patients with ulcerative colitis and Crohn's disease with positive goblet cell staining than in the biopsies from those patients with negative goblet cell staining. Almost all positive goblet cell staining in ulcerative colitis and Crohn's disease occurred in biopsies that were actively inflamed, whereas there was rare staining in biopsies that were noninflamed (regardless of whether or not there was active inflammation elsewhere in the colon). Ileal goblet cells stained positively with A13D8 only in cases of active ileitis. In cases of collagenous colitis, with comparable degrees of inflammation to that seen in ulcerative colitis and Crohn's disease, there was rarely goblet cell staining and in graft-versus-host disease goblet cell staining of A13D8 was not observed. The binding of A13D8 to tissue sections was completely inhibited by N-acetyl-D-galactosamine. These results, in conjunction with immunochemical studies, suggest that the antibody recognizes an N-acetyl-D galactosamine-containing epitope on a glycoprotein(s). In conclusion, these data suggest that A13D8 recognizes a glycoprotein expressed by intestinal columnar epithelial cells and during specific inflammatory states, particularly those associated with a neutrophilic infiltrate, becomes evident in goblet cells. Further work is required to establish the exact nature of this molecule and whether it is a pro- or anti-inflammatory factor.

Postacute, home-based head injury rehabilitation: an outcome study

A functional scale was developed to evaluate gains made by head-injured clients involved in an intensive home-based rehabilitation program. The scale was designed to assess achievement in areas of practical daily skills that can be correlated with rehabilitation outcome. This research project assessed functional changes in head-injured clients with the expectation of their being able to decrease their dependence on caretakers. This article discusses the development of a home-based rehabilitation program, the creation of the functional scale, and the results of the project.

Hypersensitivity reaction to single contrast barium meal studies in children

We report two children who developed hypersensitivity reactions of varying severity following barium meal examination, the more severe of which was associated with documented severe food allergy. For children with this risk factor, contrast studies should be performed only where facilities and personnel are available for immediate resuscitation of all sizes of child. For children such as these, consideration should be given to the use of pure barium sulphate.

Behavioral management of the agitated head trauma client

This article identifies practical application of behavior management for the agitated head-injured client (Rancho levels III-V). In addition to the suggestions offered in the article, family counseling and education modalities can be used to meet the unique needs of the agitated head-injured individual.

Reduced pH increases recovery from radiation damage potentially leading to cell death and to in vitro transformation

C3H-10T1/2 cells were grown to plateau phase and assessed for recovery from radiation damage under acidic and normal pH conditions. Repair of potentially lethal damage (PLD) was observed after X-ray doses of 5.0, 6.0 and 12.0 Gy and repair increased with dose. The repair at an acidic pH of 6.8 was greater than at the normal pH of 7.4. Repair of potentially transforming damage (PTD) was also observed when cells were held in plateau phase after irradiation. Repair of PTD was greater at the acidic pH than at the normal pH. When PTD recovery was plotted vs PLD recovery the results showed a good linear correlation with approximately twice as much PTDR. The experimental conditions allowing PLDR and PTDR indicate that the repair process may be error-free, since transformation was reduced in all experiments which showed recovery from PLD.

Normal cells and malignant cells transfected with the HRas oncogene have the same heat sensitivity in culture

Mouse embryo cells (C3H 10T1/2) were transfected with a plasmid (pAL8A) containing the HRas oncogene and neomycin resistance gene. Five transfected cell clones were isolated and established as cell lines, and these showed neomycin resistance. Two of these cell lines expressed a normal morphology while three showed a transformed morphology. Four of the cell lines produced tumours in nude mice. Flow cytometry measurements showed that exponentially growing cell cultures of the five transfected cell lines had the same cell cycle distribution as the normal parental cell line. The sensitivity to hyperthermia of the five transfected cell lines was the same as that of the normal cell line for temperatures ranging from 42.0 to 45.0 degrees C. Thus in these studies we found no difference in the thermal sensitivity of normal and malignant cells transfected by the Hras oncogene.