Characterization of wooden breast myopathy: a focus on syndecans and ECM remodeling

Introduction: The skeletal muscle deformity of commercial chickens (Gallus gallus), known as the wooden breast (WB), is associated with fibrotic myopathy of unknown etiology. For future breeding strategies and genetic improvements, it is essential to identify the molecular mechanisms underlying the phenotype. The pathophysiological hallmarks of WB include severe skeletal muscle fibrosis, inflammation, myofiber necrosis, and multifocal degeneration of muscle tissue. The transmembrane proteoglycans syndecans have a wide spectrum of biological functions and are master regulators of tissue homeostasis. They are upregulated and shed (cleaved) as a regulatory mechanism during tissue repair and regeneration. During the last decades, it has become clear that the syndecan family also has critical functions in skeletal muscle growth, however, their potential involvement in WB pathogenesis is unknown. Methods: In this study, we have categorized four groups of WB myopathy in broiler chickens and performed a comprehensive characterization of the molecular and histological profiles of two of them, with a special focus on the role of the syndecans and remodeling of the extracellular matrix (ECM). Results and discussion: Our findings reveal differential expression and shedding of the four syndecan family members and increased matrix metalloproteinase activity. Additionally, we identified alterations in key signaling pathways such as MAPK, AKT, and Wnt. Our work provides novel insights into a deeper understanding of WB pathogenesis and suggests potential therapeutic targets for this condition.

Polyarginine Cell-Penetrating Peptides Bind and Inhibit SERCA2

Cell-penetrating peptides (CPPs) are short peptide sequences that have the ability to cross the cell membrane and deliver cargo. Although it is critical that CPPs accomplish this task with minimal off-target effects, such actions have in many cases not been robustly screened. We presently investigated whether the commonly used CPPs TAT and the polyarginines Arg9 and Arg11 exert off-target effects on cellular Ca2+ homeostasis. In experiments employing myocytes and homogenates from the cardiac left ventricle or soleus muscle, we observed marked inhibition of Ca2+ recycling into the sarcoplasmic reticulum (SR) following incubation with polyarginine CPPs. In both tissues, the rate of SR Ca2+ leak remained unchanged, indicating that protracted Ca2+ removal from the cytosol stemmed from inhibition of the SR Ca2+ ATPase 2 (SERCA2). No such inhibition occurred following treatment with TAT, or in preparations from the SERCA1-expressing extensor digitorum longus muscle. Experiments in HEK cells overexpressing individual SERCA isoforms confirmed that polyarginine incubation specifically inhibited the activity of SERCA2a and 2b, but not SERCA1 or 3. The attenuation of SERCA2 activity was not dependent on the presence of phospholamban, and ELISA-based analyses rather revealed direct interaction between the polyarginines and the actuator domain of the protein. Surface plasmon resonance experiments confirmed strong binding within this region of SERCA2, and slow dissociation between the two species. Based on these observations, we urge caution when employing polyarginine CPPs. Indeed, as SERCA2 is expressed in diverse cell types, the wide-ranging consequences of SERCA2 binding and inhibition should be anticipated in both experimental and therapeutic settings.

BIN1, Myotubularin, and Dynamin-2 Coordinate T-Tubule Growth in Cardiomyocytes

BACKGROUND

Transverse tubules (t-tubules) form gradually in the developing heart, critically enabling maturation of cardiomyocyte Ca²⁺ homeostasis. The membrane bending and scaffolding protein BIN1 (amphiphysin-2) has been implicated in this process. However, it is unclear which of the various reported BIN1 isoforms are involved, and whether BIN1 function is regulated by its putative binding partners MTM1 (myotubularin), a phosphoinositide 3'-phosphatase, and DNM2 (dynamin-2), a GTPase believed to mediate membrane fission.

METHODS

We investigated the roles of BIN1, MTM1, and DNM2 in t-tubule formation in developing mouse cardiomyocytes, and in gene-modified HL-1 and human-induced pluripotent stem cell-derived cardiomyocytes. T-tubules and proteins of interest were imaged by confocal and Airyscan microscopy, and expression patterns were examined by RT-qPCR and Western blotting. Ca²⁺ release was recorded using Fluo-4.

RESULTS

We observed that in the postnatal mouse heart, BIN1 localizes along Z-lines from early developmental stages, consistent with roles in initial budding and scaffolding of t-tubules. T-tubule proliferation and organization were linked to a progressive and parallel increase in 4 detected BIN1 isoforms. All isoforms were observed to induce tubulation in cardiomyocytes but produced t-tubules with differing geometries. BIN1-induced tubulations contained the L-type Ca²⁺ channel, were colocalized with caveolin-3 and the ryanodine receptor, and effectively triggered Ca²⁺ release. BIN1 upregulation during development was paralleled by increasing expression of MTM1. Despite no direct binding between MTM1 and murine cardiac BIN1 isoforms, which lack exon 11, high MTM1 levels were necessary for BIN1-induced tubulation, indicating a central role of phosphoinositide homeostasis. In contrast, the developing heart exhibited declining levels of DNM2. Indeed, we observed that high levels of DNM2 are inhibitory for t-tubule formation, although this protein colocalizes with BIN1 along Z-lines, and binds all 4 isoforms.

CONCLUSIONS

These findings indicate that BIN1, MTM1, and DNM2 have balanced and collaborative roles in controlling t-tubule growth in cardiomyocytes.

Disruption of Phosphodiesterase 3A Binding to SERCA2 Increases SERCA2 Activity and Reduces Mortality in Mice With Chronic Heart Failure

BACKGROUND

Increasing SERCA2 (sarco[endo]-plasmic reticulum Ca2+ ATPase 2) activity is suggested to be beneficial in chronic heart failure, but no selective SERCA2-activating drugs are available. PDE3A (phosphodiesterase 3A) is proposed to be present in the SERCA2 interactome and limit SERCA2 activity. Disruption of PDE3A from SERCA2 might thus be a strategy to develop SERCA2 activators.

METHODS

Confocal microscopy, 2-color direct stochastic optical reconstruction microscopy, proximity ligation assays, immunoprecipitations, peptide arrays, and surface plasmon resonance were used to investigate colocalization between SERCA2 and PDE3A in cardiomyocytes, map the SERCA2/PDE3A interaction sites, and optimize disruptor peptides that release PDE3A from SERCA2. Functional experiments assessing the effect of PDE3A-binding to SERCA2 were performed in cardiomyocytes and HEK293 vesicles. The effect of SERCA2/PDE3A disruption by the disruptor peptide OptF (optimized peptide F) on cardiac mortality and function was evaluated during 20 weeks in 2 consecutive randomized, blinded, and controlled preclinical trials in a total of 148 mice injected with recombinant adeno-associated virus 9 (rAAV9)-OptF, rAAV9-control (Ctrl), or PBS, before undergoing aortic banding (AB) or sham surgery and subsequent phenotyping with serial echocardiography, cardiac magnetic resonance imaging, histology, and functional and molecular assays.

RESULTS

PDE3A colocalized with SERCA2 in human nonfailing, human failing, and rodent myocardium. Amino acids 277-402 of PDE3A bound directly to amino acids 169-216 within the actuator domain of SERCA2. Disruption of PDE3A from SERCA2 increased SERCA2 activity in normal and failing cardiomyocytes. SERCA2/PDE3A disruptor peptides increased SERCA2 activity also in the presence of protein kinase A inhibitors and in phospholamban-deficient mice, and had no effect in mice with cardiomyocyte-specific inactivation of SERCA2. Cotransfection of PDE3A reduced SERCA2 activity in HEK293 vesicles. Treatment with rAAV9-OptF reduced cardiac mortality compared with rAAV9-Ctrl (hazard ratio, 0.26 [95% CI, 0.11 to 0.63]) and PBS (hazard ratio, 0.28 [95% CI, 0.09 to 0.90]) 20 weeks after AB. Mice injected with rAAV9-OptF had improved contractility and no difference in cardiac remodeling compared with rAAV9-Ctrl after aortic banding.

CONCLUSIONS

Our results suggest that PDE3A regulates SERCA2 activity through direct binding, independently of the catalytic activity of PDE3A. Targeting the SERCA2/PDE3A interaction prevented cardiac mortality after AB, most likely by improving cardiac contractility.

The female syndecan-4−/− heart has smaller cardiomyocytes, augmented insulin/pSer473-Akt/pSer9-GSK-3β signaling, and lowered SCOP, pThr308-Akt/Akt and GLUT4 levels

Background: In cardiac muscle, the ubiquitously expressed proteoglycan syndecan-4 is involved in the hypertrophic response to pressure overload. Protein kinase Akt signaling, which is known to regulate hypertrophy, has been found to be reduced in the cardiac muscle of exercised male syndecan-4−/− mice. In contrast, we have recently found that pSer473-Akt signaling is elevated in the skeletal muscle (tibialis anterior, TA) of female syndecan-4−/− mice. To determine if the differences seen in Akt signaling are sex specific, we have presently investigated Akt signaling in the cardiac muscle of sedentary and exercised female syndecan-4−/− mice. To get deeper insight into the female syndecan-4−/− heart, alterations in cardiomyocyte size, a wide variety of different extracellular matrix components, well-known syndecan-4 binding partners and associated signaling pathways have also been investigated.

Methods: Left ventricles (LVs) from sedentary and exercise trained female syndecan-4−/− and WT mice were analyzed by immunoblotting and real-time PCR. Cardiomyocyte size and phosphorylated Ser473-Akt were analyzed in isolated adult cardiomyocytes from female syndecan-4−/− and WT mice by confocal imaging. LV and skeletal muscle (TA) from sedentary male syndecan-4−/− and WT mice were immunoblotted with Akt antibodies for comparison. Glucose levels were measured by a glucometer, and fasting blood serum insulin and C-peptide levels were measured by ELISA.

Results: Compared to female WT hearts, sedentary female syndecan-4−/− LV cardiomyocytes were smaller and hearts had higher levels of pSer473-Akt and its downstream target pSer9-GSK-3β. The pSer473-Akt inhibitory phosphatase PHLPP1/SCOP was lowered, which may be in response to the elevated serum insulin levels found in the female syndecan-4−/− mice. We also observed lowered levels of pThr308-Akt/Akt and GLUT4 in the female syndecan-4−/− heart and an increased LRP6 level after exercise. Otherwise, few alterations were found. The pThr308-Akt and pSer473-Akt levels were unaltered in the cardiac and skeletal muscles of sedentary male syndecan-4−/− mice.

Conclusion: Our data indicate smaller cardiomyocytes, an elevated insulin/pSer473-Akt/pSer9-GSK-3β signaling pathway, and lowered SCOP, pThr308-Akt/Akt and GLUT4 levels in the female syndecan-4−/− heart. In contrast, cardiomyocyte size, and Akt signaling were unaltered in both cardiac and skeletal muscles from male syndecan-4−/− mice, suggesting important sex differences.

AKAP18δ Anchors and Regulates CaMKII Activity at Phospholamban-SERCA2 and RYR

BACKGROUND

The sarcoplasmic reticulum (SR) Ca²⁺-ATPase 2 (SERCA2) mediates Ca²⁺ reuptake into SR and thereby promotes cardiomyocyte relaxation, whereas the ryanodine receptor (RYR) mediates Ca²⁺ release from SR and triggers contraction. Ca²⁺/CaMKII (CaM [calmodulin]-dependent protein kinase II) regulates activities of SERCA2 through phosphorylation of PLN (phospholamban) and RYR through direct phosphorylation. However, the mechanisms for CaMKIIδ anchoring to SERCA2-PLN and RYR and its regulation by local Ca²⁺ signals remain elusive. The objective of this study was to investigate CaMKIIδ anchoring and regulation at SERCA2-PLN and RYR.

METHODS

A role for AKAP18δ (A-kinase anchoring protein 18δ) in CaMKIIδ anchoring and regulation was analyzed by bioinformatics, peptide arrays, cell-permeant peptide technology, immunoprecipitations, pull downs, transfections, immunoblotting, proximity ligation, FRET-based CaMKII activity and ELISA-based assays, whole cell and SR vesicle fluorescence imaging, high-resolution microscopy, adenovirus transduction, adenoassociated virus injection, structural modeling, surface plasmon resonance, and alpha screen technology.

RESULTS

Our results show that AKAP18δ anchors and directly regulates CaMKIIδ activity at SERCA2-PLN and RYR, via 2 distinct AKAP18δ regions. An N-terminal region (AKAP18δ-N) inhibited CaMKIIδ through binding of a region homologous to the natural CaMKII inhibitor peptide and the Thr17-PLN region. AKAP18δ-N also bound CaM, introducing a second level of control. Conversely, AKAP18δ-C, which shares homology to neuronal CaMKIIα activator peptide (N2B-s), activated CaMKIIδ by lowering the apparent Ca²⁺ threshold for kinase activation and inducing CaM trapping. While AKAP18δ-C facilitated faster Ca²⁺ reuptake by SERCA2 and Ca²⁺ release through RYR, AKAP18δ-N had opposite effects. We propose a model where the 2 unique AKAP18δ regions fine-tune Ca²⁺-frequency-dependent activation of CaMKIIδ at SERCA2-PLN and RYR.

CONCLUSIONS

AKAP18δ anchors and functionally regulates CaMKII activity at PLN-SERCA2 and RYR, indicating a crucial role of AKAP18δ in regulation of the heartbeat. To our knowledge, this is the first protein shown to enhance CaMKII activity in heart and also the first AKAP (A-kinase anchoring protein) reported to anchor a CaMKII isoform, defining AKAP18δ also as a CaM-KAP.

Design of a Proteolytically Stable Sodium-Calcium Exchanger 1 Activator Peptide for In Vivo Studies

The cardiac sodium–calcium exchanger (NCX1) is important for normal Na⁺- and Ca²⁺-homeostasis and cardiomyocyte relaxation and contraction. It has been suggested that NCX1 activity is reduced by phosphorylated phospholemman (pSer68-PLM); however its direct interaction with PLM is debated. Disruption of the potentially inhibitory pSer68-PLM-NCX1 interaction might be a therapeutic strategy to increase NCX1 activity in cardiac disease. In the present study, we aimed to analyze the binding affinities and kinetics of the PLM-NCX1 and pSer68-PLM-NCX1 interactions by surface plasmon resonance (SPR) and to develop a proteolytically stable NCX1 activator peptide for future in vivo studies. The cytoplasmic parts of PLM (PLM_cyt) and pSer68-PLM (pSer68-PLM_cyt) were found to bind strongly to the intracellular loop of NCX1 (NCX1_cyt) with similar K_D values of 4.1 ± 1.0 nM and 4.3 ± 1.9 nM, but the PLM_cyt-NCX1_cyt interaction showed higher on/off rates. To develop a proteolytically stable NCX1 activator, we took advantage of a previously designed, high-affinity PLM binding peptide (OPT) that was derived from the PLM binding region in NCX1 and that reverses the inhibitory PLM (S68D)-NCX1 interaction in HEK293. We performed N- and C-terminal truncations of OPT and identified PYKEIEQLIELANYQV as the minimum sequence required for pSer68-PLM binding. To increase peptide stability in human serum, we replaced the proline with an N-methyl-proline (NOPT) after identification of N-terminus as substitution tolerant by two-dimensional peptide array analysis. Mass spectrometry analysis revealed that the half-life of NOPT was increased 17-fold from that of OPT. NOPT pulled down endogenous PLM from rat left ventricle lysate and exhibited direct pSer68-PLM binding in an ELISA-based assay and bound to pSer68-PLM_cyt with a K_D of 129 nM. Excess NOPT also reduced the PLM_cyt-NCX1_cyt interaction in an ELISA-based competition assay, but in line with that NCX1 and PLM form oligomers, NOPT was not able to outcompete the physical interaction between endogenous full length proteins. Importantly, cell-permeable NOPT-TAT increased NCX1 activity in cardiomyocytes isolated from both SHAM-operated and aorta banded heart failure (HF) mice, indicating that NOPT disrupted the inhibitory pSer68-PLM-NCX1 interaction. In conclusion, we have developed a proteolytically stable NCX1-derived PLM binding peptide that upregulates NCX1 activity in SHAM and HF cardiomyocytes.

The Cardiac Syndecan-2 Interactome

The extracellular matrix (ECM) is important in cardiac remodeling and syndecans have gained increased interest in this process due to their ability to convert changes in the ECM to cell signaling. In particular, syndecan-4 has been shown to be important for cardiac remodeling, whereas the role of its close relative syndecan-2 is largely unknown in the heart. To get more insight into the role of syndecan-2, we here sought to identify interaction partners of syndecan-2 in rat left ventricle. By using three different affinity purification methods combined with mass spectrometry (MS) analysis, we identified 30 novel partners and 9 partners previously described in the literature, which together make up the first cardiac syndecan-2 interactome. Eleven of the novel partners were also verified in HEK293 cells (i.e., AP2A2, CAVIN2, DDX19A, EIF4E, JPH2, MYL12A, NSF, PFDN2, PSMC5, PSMD11, and RRAD). The cardiac syndecan-2 interactome partners formed connections to each other and grouped into clusters mainly involved in cytoskeletal remodeling and protein metabolism, but also into a cluster consisting of a family of novel syndecan-2 interaction partners, the CAVINs. MS analyses revealed that although syndecan-2 was significantly enriched in fibroblast fractions, most of its partners were present in both cardiomyocytes and fibroblasts. Finally, a comparison of the cardiac syndecan-2 and -4 interactomes revealed surprisingly few protein partners in common.

Syndecan-4-/- Mice Have Smaller Muscle Fibers, Increased Akt/mTOR/S6K1 and Notch/HES-1 Pathways, and Alterations in Extracellular Matrix Components

Background

Extracellular matrix (ECM) remodeling is essential for skeletal muscle development and adaption in response to environmental cues such as exercise and injury. The cell surface proteoglycan syndecan-4 has been reported to be essential for muscle differentiation, but few molecular mechanisms are known. Syndecan-4^–/– mice are unable to regenerate damaged muscle, and display deficient satellite cell activation, proliferation, and differentiation. A reduced myofiber basal lamina has also been reported in syndecan-4^–/– muscle, indicating possible defects in ECM production. To get a better understanding of the underlying molecular mechanisms, we have here investigated the effects of syndecan-4 genetic ablation on molecules involved in ECM remodeling and muscle growth, both under steady state conditions and in response to exercise.

Methods

Tibialis anterior (TA) muscles from sedentary and exercised syndecan-4^–/– and WT mice were analyzed by immunohistochemistry, real-time PCR and western blotting.

Results

Compared to WT, we found that syndecan-4^–/– mice had reduced body weight, reduced muscle weight, muscle fibers with a smaller cross-sectional area, and reduced expression of myogenic regulatory transcription factors. Sedentary syndecan-4^–/– had also increased mRNA levels of syndecan-2, decorin, collagens, fibromodulin, biglycan, and LOX. Some of these latter ECM components were reduced at protein level, suggesting them to be more susceptible to degradation or less efficiently translated when syndecan-4 is absent. At the protein level, TRPC7 was reduced, whereas activation of the Akt/mTOR/S6K1 and Notch/HES-1 pathways were increased. Finally, although exercise induced upregulation of several of these components in WT, a further upregulation of these molecules was not observed in exercised syndecan-4^–/– mice.

Conclusion

Altogether our data suggest an important role of syndecan-4 in muscle development.

Secretoneurin Is an Endogenous Calcium/Calmodulin-Dependent Protein Kinase II Inhibitor That Attenuates Ca2+-Dependent Arrhythmia

BACKGROUND

Circulating SN (secretoneurin) concentrations are increased in patients with myocardial dysfunction and predict poor outcome. Because SN inhibits CaMKIIδ (Ca²⁺/calmodulin-dependent protein kinase IIδ) activity, we hypothesized that upregulation of SN in patients protects against cardiomyocyte mechanisms of arrhythmia.

METHODS

Circulating levels of SN and other biomarkers were assessed in patients with catecholaminergic polymorphic ventricular tachycardia (CPVT; n=8) and in resuscitated patients after ventricular arrhythmia-induced cardiac arrest (n=155). In vivo effects of SN were investigated in CPVT mice (RyR2 [ryanodine receptor 2]-R2474S) using adeno-associated virus-9-induced overexpression. Interactions between SN and CaMKIIδ were mapped using pull-down experiments, mutagenesis, ELISA, and structural homology modeling. Ex vivo actions were tested in Langendorff hearts and effects on Ca²⁺ homeostasis examined by fluorescence (fluo-4) and patch-clamp recordings in isolated cardiomyocytes.

RESULTS

SN levels were elevated in patients with CPVT and following ventricular arrhythmia-induced cardiac arrest. In contrast to NT-proBNP (N-terminal pro-B-type natriuretic peptide) and hs-TnT (high-sensitivity troponin T), circulating SN levels declined after resuscitation, as the risk of a new arrhythmia waned. Myocardial pro-SN expression was also increased in CPVT mice, and further adeno-associated virus-9-induced overexpression of SN attenuated arrhythmic induction during stress testing with isoproterenol. Mechanistic studies mapped SN binding to the substrate binding site in the catalytic region of CaMKIIδ. Accordingly, SN attenuated isoproterenol induced autophosphorylation of Thr287-CaMKIIδ in Langendorff hearts and inhibited CaMKIIδ-dependent RyR phosphorylation. In line with CaMKIIδ and RyR inhibition, SN treatment decreased Ca²⁺ spark frequency and dimensions in cardiomyocytes during isoproterenol challenge, and reduced the incidence of Ca²⁺ waves, delayed afterdepolarizations, and spontaneous action potentials. SN treatment also lowered the incidence of early afterdepolarizations during isoproterenol; an effect paralleled by reduced magnitude of L-type Ca²⁺ current.

CONCLUSIONS

SN production is upregulated in conditions with cardiomyocyte Ca²⁺ dysregulation and offers compensatory protection against cardiomyocyte mechanisms of arrhythmia, which may underlie its putative use as a biomarker in at-risk patients.

The cardiac syndecan-4 interactome reveals a role for syndecan-4 in nuclear translocation of muscle LIM protein (MLP)

Costameres are signaling hubs at the sarcolemma and important contact points between the extracellular matrix and cell interior, sensing and transducing biomechanical signals into a cellular response. The transmembrane proteoglycan syndecan-4 localizes to these attachment points and has been shown to be important in the initial stages of cardiac remodeling, but its mechanistic function in the heart remains insufficiently understood. Here, we sought to map the cardiac interactome of syndecan-4 to better understand its function and downstream signaling mechanisms. By combining two different affinity purification methods with MS analysis, we found that the cardiac syndecan-4 interactome consists of 21 novel and 29 previously described interaction partners. Nine of the novel partners were further validated to bind syndecan-4 in HEK293 cells (i.e. CAVIN1/PTRF, CCT5, CDK9, EIF2S1, EIF4B, MPP7, PARVB, PFKM, and RASIP). We also found that 19 of the 50 interactome partners bind differently to syndecan-4 in the left ventricle lysate from aortic-banded heart failure (ABHF) rats compared with SHAM-operated animals. One of these partners was the well-known mechanotransducer muscle LIM protein (MLP), which showed direct and increased binding to syndecan-4 in ABHF. Nuclear translocation is important in MLP-mediated signaling, and we found less MLP in the nuclear-enriched fractions from syndecan-4^-/- mouse left ventricles but increased nuclear MLP when syndecan-4 was overexpressed in a cardiomyocyte cell line. In the presence of a cell-permeable syndecan-4-MLP disruptor peptide, the nuclear MLP level was reduced. These findings suggest that syndecan-4 mediates nuclear translocation of MLP in the heart.

Mapping the in vitro interactome of cardiac sodium (Na+ )-calcium (Ca2+ ) exchanger 1 (NCX1)

The sodium (Na⁺ )-calcium (Ca²⁺ ) exchanger 1 (NCX1) is an antiporter membrane protein encoded by the SLC8A1 gene. In the heart, it maintains cytosolic Ca²⁺ homeostasis, serving as the primary mechanism for Ca²⁺ extrusion during relaxation. Dysregulation of NCX1 is observed in end-stage human heart failure. In this study, we used affinity purification coupled with MS in rat left ventricle lysates to identify novel NCX1 interacting proteins in the heart. Two screens were conducted using: (1) anti-NCX1 against endogenous NCX1 and (2) anti-His (where His is histidine) with His-trigger factor-NCX1_cyt recombinant protein as bait. The respective methods identified 112 and 350 protein partners, of which several were known NCX1 partners from the literature, and 29 occurred in both screens. Ten novel protein partners (DYRK1A, PPP2R2A, SNTB1, DMD, RABGGTA, DNAJB4, BAG3, PDE3A, POPDC2, STK39) were validated for binding to NCX1, and two partners (DYRK1A, SNTB1) increased NCX1 activity when expressed in HEK293 cells. A cardiac NCX1 protein-protein interaction map was constructed. The map was highly connected, containing distinct clusters of proteins with different biological functions, where "cell communication" and "signal transduction" formed the largest clusters. The NCX1 interactome was also significantly enriched with proteins/genes involved in "cardiovascular disease" which can be explored as novel drug targets in future research.

Abstract 380: Mapping the i n vitro Interactome of the Cardiac Sodium-Calcium Exchanger 1

The sodium (Na + )-calcium (Ca 2+ ) exchanger 1 (NCX1) is an antiporter membrane protein encoded by the SLC8A1 gene. In the heart, it maintains cytosolic Ca 2+ homeostasis, serving as the primary mechanism for Ca 2+ extrusion during relaxation. Dysregulation of NCX1 is observed in end-stage human heart failure. In this study we used affinity purification coupled with mass spectrometry in rat left ventricle lysates to identify novel NCX1 interacting proteins in the heart. Two screens were conducted using: 1) anti-NCX1 against endogenous NCX1 and 2) anti-His with His-TF-NCX1 cyt recombinant protein as bait. The respective methods identified 112 and 350 protein partners, of which several were known NCX1 partners from the literature and 29 occurred in both screens. Selected protein partners were validated for binding to NCX1 expressed in HEK293 cells. A cardiac NCX1 protein-protein interaction map was constructed. The map was highly connected, containing distinct clusters of proteins with different biological functions, where cell communication and signal transduction formed the largest clusters. The NCX1 interactome was also significantly enriched with proteins/genes involved in cardiovascular disease. Exploring the molecular mechanisms of these protein partners in future studies may aid in elucidation of NCX1 regulation and facilitate selective therapeutic targeting of NCX1.

Protein Phosphatase 1c Associated with the Cardiac Sodium Calcium Exchanger 1 Regulates Its Activity by Dephosphorylating Serine 68-phosphorylated Phospholemman

The sodium (Na(+))-calcium (Ca(2+)) exchanger 1 (NCX1) is an important regulator of intracellular Ca(2+) homeostasis. Serine 68-phosphorylated phospholemman (pSer-68-PLM) inhibits NCX1 activity. In the context of Na(+)/K(+)-ATPase (NKA) regulation, pSer-68-PLM is dephosphorylated by protein phosphatase 1 (PP1). PP1 also associates with NCX1; however, the molecular basis of this association is unknown. In this study, we aimed to analyze the mechanisms of PP1 targeting to the NCX1-pSer-68-PLM complex and hypothesized that a direct and functional NCX1-PP1 interaction is a prerequisite for pSer-68-PLM dephosphorylation. Using a variety of molecular techniques, we show that PP1 catalytic subunit (PP1c) co-localized, co-fractionated, and co-immunoprecipitated with NCX1 in rat cardiomyocytes, left ventricle lysates, and HEK293 cells. Bioinformatic analysis, immunoprecipitations, mutagenesis, pulldown experiments, and peptide arrays constrained PP1c anchoring to the K(I/V)FF motif in the first Ca(2+) binding domain (CBD) 1 in NCX1. This binding site is also partially in agreement with the extended PP1-binding motif K(V/I)FF-X5-8Φ1Φ2-X8-9-R. The cytosolic loop of NCX1, containing the K(I/V)FF motif, had no effect on PP1 activity in an in vitro assay. Dephosphorylation of pSer-68-PLM in HEK293 cells was not observed when NCX1 was absent, when the K(I/V)FF motif was mutated, or when the PLM- and PP1c-binding sites were separated (mimicking calpain cleavage of NCX1). Co-expression of PLM and NCX1 inhibited NCX1 current (both modes). Moreover, co-expression of PLM with NCX1(F407P) (mutated K(I/V)FF motif) resulted in the current being completely abolished. In conclusion, NCX1 is a substrate-specifying PP1c regulator protein, indirectly regulating NCX1 activity through pSer-68-PLM dephosphorylation.

Psychometric evaluation of the Major Depression Inventory (MDI) as depression severity scale using the LEAD (Longitudinal Expert Assessment of All Data) as index of validity

BACKGROUND

The Major Depression Inventory (MDI) was developed to cover the universe of depressive symptoms in DSM-IV major depression as well as in ICD-10 mild, moderate, and severe depression. The objective of this study was to evaluate the standardization of the MDI as a depression severity scale using the Visual Analogue Scale (VAS) as index of external validity in accordance with the LEAD approach (Longitudinal Expert Assessment of All Data).

METHODS

We used data from two previously published studies in which the patients had a MINI Neuropsychiatric Interview verified diagnosis of DSM-IV major depression. The conventional VAS scores for no, mild, moderate, and severe depression were used for the standardization of the MDI.

RESULTS

The inter-correlation for the MDI with the clinician ratings (VAS, MES, HAM-D17 and HAM-D6) increased over the rating weeks in terms of Pearson coefficients. After nine weeks of therapy the coefficient ranged from 0.74 to 0.83. Using the clinician-rated VAS depression severity scale, the conventional MDI cut-off scores for no or doubtful depression, and for mild, moderate and severe depression were confirmed.

CONCLUSIONS

Using the VAS as index of external, clinical validity, the standardization of the MDI as a measure of depression severity was accepted, with an MDI cut-off score of 21 for mild depression, 26 for moderate depression severity, and 31 for severe depression.

TRIAL REGISTRATION

Martiny et al. Acta Psychiatr Scand 112:117-25, 2005: None - due to trial commencement date. Straaso et al. Acta Neuropsychiatr 26:272-9; 2014: ClinicalTrials.gov ID NCT01353092 .

Maintained superiority of chronotherapeutics vs. exercise in a 20-week randomized follow-up trial in major depression

OBJECTIVE

To investigate the long-term antidepressant effect of a chronotherapeutic intervention.

METHOD

In this randomized controlled trial 75 patients with major depression were allocated to fixed duloxetine and either a chronotherapeutic intervention (wake group) with three initial wake therapies, daily bright light therapy, and sleep time stabilization or to a group using daily exercise. Patients were followed 29 weeks. We report the last 20 weeks, a follow-up phase, where medication could be altered. Patients were assessed every 4 weeks. Remission rates were primary outcome.

RESULTS

Patients in the wake group had a statistically significant higher remission rate of 61.9% vs. 37.9% in the exercise group at week 29 (OR = 2.6, CL = 1.3-5.6, P = 0.01). This indicated continued improvement compared with the 9 weeks of treatment response (44.8% vs. 23.4%) with maintenance of the large difference between groups. HAM-D17 endpoint scores were statistically lower in the wake group with endpoint scores of 7.5 (SE = 0.9) vs. 10.1 (SE = 0.9) in the exercise group (difference 2.7, CL = 0.5-4.8, P = 0.02).

CONCLUSION

In this clinical study patients continued to improve in the follow-up phase and obtained very high remission rates. This is the first study to show adjunct short-term wake therapy and long-term bright light therapy as an effective and feasible method to attain and maintain remission.

Molecular basis of calpain cleavage and inactivation of the sodium-calcium exchanger 1 in heart failure

Cardiac sodium (Na(+))-calcium (Ca(2+)) exchanger 1 (NCX1) is central to the maintenance of normal Ca(2+) homeostasis and contraction. Studies indicate that the Ca(2+)-activated protease calpain cleaves NCX1. We hypothesized that calpain is an important regulator of NCX1 in response to pressure overload and aimed to identify molecular mechanisms and functional consequences of calpain binding and cleavage of NCX1 in the heart. NCX1 full-length protein and a 75-kDa NCX1 fragment along with calpain were up-regulated in aortic stenosis patients and rats with heart failure. Patients with coronary artery disease and sham-operated rats were used as controls. Calpain co-localized, co-fractionated, and co-immunoprecipitated with NCX1 in rat cardiomyocytes and left ventricle lysate. Immunoprecipitations, pull-down experiments, and extensive use of peptide arrays indicated that calpain domain III anchored to the first Ca(2+) binding domain in NCX1, whereas the calpain catalytic region bound to the catenin-like domain in NCX1. The use of bioinformatics, mutational analyses, a substrate competitor peptide, and a specific NCX1-Met(369) antibody identified a novel calpain cleavage site at Met(369). Engineering NCX1-Met(369) into a tobacco etch virus protease cleavage site revealed that specific cleavage at Met(369) inhibited NCX1 activity (both forward and reverse mode). Finally, a short peptide fragment containing the NCX1-Met(369) cleavage site was modeled into the narrow active cleft of human calpain. Inhibition of NCX1 activity, such as we have observed here following calpain-induced NCX1 cleavage, might be beneficial in pathophysiological conditions where increased NCX1 activity contributes to cardiac dysfunction.

Two of three patients with multiple chemical sensitivity had less symptoms and secondary hyperalgesia after transcranially applied pulsed electromagnetic fields

Background Multiple chemical sensitivity (MCS) is a chronic, disabling condition characterized by recurrent multisystem symptoms triggered by common airborne chemicals. Evidence points towards abnormal sensory processing in the central nervous system (CNS) as a likely pathophysiological mechanism. No effective treatment has yet been reported, but clinical observations suggest that as pulsed electromagnetic fields (PEMF) is a treatment for some CNS disorders (depression and chronic pain), it may also be a treatment modality for MCS. Methods In an open case study, the effects of PEMF were assessed in three MCS patients. All cases received 30 min daily treatment 5 days a week for 8 consecutive weeks. Symptoms and functional impairments related to MCS, depressive symptoms, and capsaicin-induced secondary punctate hyperalgesia were assessed at baseline and weekly until an 18-week follow-up. Results Two of the three cases showed considerable improvement on all measures of symptoms and functional impairments related to MCS in response to PEMF therapy. One case showed no improvement and during the treatment period was unexpectedly diagnosed with depression. Conclusion Our findings indicate potential benefits of PEMF therapy in MCS. Implication The therapeutic effect of PEMF in MCS needs to be investigated by a randomized placebo-controlled trial.

The day-to-day acute effect of wake therapy in patients with major depression using the HAM-D6 as primary outcome measure: results from a randomised controlled trial

BACKGROUND

This paper reports day-to-day data for from a one-week intervention phase, part of a 9-weeks randomised parallel study with patient having major depression (data from weekly visits have been reported). Wake therapy (sleep deprivation) has an established antidepressant effect with onset of action within hours. Deterioration on the following night's sleep is, however, common, and we used daily light therapy and sleep time stabilisation as a preventive measure. In particular, we evaluated the day-to-day acute effect of and tolerance to sleep deprivation and examined predictors of response.

METHODS

Patients were assessed at psychiatric inpatient wards. In the wake group (n = 36), patients did three wake therapies in combination with light therapy each morning together with sleep time stabilisation. In the exercise group (n = 38), patients did daily exercise. Hamilton subscale scores were primary outcome (not blinded), secondary outcome was self-assessment data from the Preskorn scale and sleep.

RESULTS

Patients in the wake therapy group had an immediate, large, stable, and statistically significant better antidepressant effect than patients in the exercise group with response rates at day5 of 75.0%/25.1% and remission rates of 58.6%/6.0%, respectively. The response and remission rates were diminished at day8 with response rates of 41.9%/10.1% and remission rates of 19.4%/4.7%, respectively. Patients and ward personnel found the method applicable with few side effects. Positive diurnal variation (mood better in the evening) predicted a larger response to wake therapy. In the wake group napping on days after intervention predicted greater deterioration on day8.

CONCLUSIONS

The intervention induced an acute antidepressant response without relapse between wake nights but with a diminishing effect after intervention. Development is still needed to secure maintenance of response. Avoiding napping in the days after wake therapy is important.

TRIAL REGISTRATION

Clinical trials.gov NCT00149110.

Eysenck's Two Big Personality Factors and Their Relationship to Depression in Patients with Chronic Idiopathic Pain Disorder: A Clinimetric Validation Analysis

Aim. The clinimetric aspects of Eysenck's two big personality factors (neuroticism and extraversion) were originally identified by principal component analysis but have been insufficiently analysed with item response theory models. Their relationship to states of melancholia and anxiety was subsequently analysed. Method. Patients with chronic idiopathic pain disorder were included in the study. The nonparametric item response model (Mokken) was compared to the coefficient alpha to validate the anxiety and depression subscales within the neuroticism scale and the extraversion and introversion subscales within the extraversion scale. When measuring states of depression and anxiety, the Melancholia Scale and the Hamilton Anxiety Scale were used. Results. We identified acceptable subscales of anxiety and depression in the Eysenck factor of neuroticism and extraversion versus introversion subscales within the Eysenck factor of extraversion. Focusing on the item of “Does your mood often go up and down?” we showed a statistically significant association with melancholia and anxiety for patients with a positive score on this item. Conclusion. Within the Eysenck factor of neuroticism it is important to differentiate between the anxiety and depression subscales. The clinimetric analysis of the Eysenck factor of extraversion identified valid subscales.

A 9-week randomized trial comparing a chronotherapeutic intervention (wake and light therapy) to exercise in major depressive disorder patients treated with duloxetine

OBJECTIVE

The onset of action of antidepressants often takes 4 to 6 weeks. The antidepressant effect of wake therapy (sleep deprivation) comes within hours but carries a risk of relapse. The objective of this study was to investigate whether a new chronotherapeutic intervention combining wake therapy with bright light therapy and sleep time stabilization could induce a rapid and sustained augmentation of response and remission in major depressive disorder.

METHOD

75 adult patients with DSM-IV major depressive disorder, recruited from psychiatric wards, psychiatric specialist practices, or general medical practices between September 2005 and August 2008, were randomly assigned to a 9-week chronotherapeutic intervention using wake therapy, bright light therapy, and sleep time stabilization (n = 37) or a 9-week intervention using daily exercise (n = 38). Patients were evaluated at a psychiatric research unit. The study period had a 1-week run-in phase in which all patients began treatment with duloxetine. This phase was followed by a 1-week intervention phase in which patients in the wake therapy group did 3 wake therapies in combination with daily morning light therapy and sleep time stabilization and patients in the exercise group began daily exercise. This phase was followed by a 7-week continuation phase with daily light therapy and sleep time stabilization or daily exercise. The 17-item Hamilton Depression Rating Scale was the primary outcome measure, and the assessors were blinded to patients' treatment allocation.

RESULTS

Both groups responded well to treatment. Patients in the wake therapy group did, however, have immediate and clinically significantly better response and remission compared to the exercise group. Thus, immediately after the intervention phase (week 2), response was obtained in 41.4% of wake therapy patients versus 12.8% of exercise patients (odds ratio [OR] = 4.8; 95% CI, 1.7-13.4; P = .003), and remission was obtained in 23.9% of wake therapy patients versus 5.4% of exercise patients (OR = 5.5; 95% CI, 1.7-17.8; P = .004). These superior response and remission rates obtained by the wake therapy patients were sustained for the whole study period. At week 9, response was obtained in 71.4% of wake therapy patients versus 47.3% of exercise patients (OR = 2.8; 95% CI, 1.1-7.3; P = .04), and remission was obtained in 45.6% of wake therapy patients and 23.1% of exercise patients (OR = 2.8; 95% CI, 1.1-7.3, P = .04). All treatment elements were well tolerated.

CONCLUSIONS

Patients treated with wake therapy in combination with bright light therapy and sleep time stabilization had an augmented and sustained antidepressant response and remission compared to patients treated with exercise, who also had a clinically relevant antidepressant response.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00149110.

A short-term double-blind randomized controlled pilot trial with active or placebo pindolol in patients treated with venlafaxine for major depression

BACKGROUND

Pindolol has been widely investigated as an augmenter of antidepressant drug response. Results have been inconsistent. In this study, we used pindolol together with venlafaxine because of its ability to achieve a rapid onset of serotonin transporter blockade.

AIMS

The object of this study was thus to investigate if pindolol augments the antidepressant response to venlafaxine.

METHODS

Patients with major depression were randomized to either active or placebo pindolol 20 mg retard daily dosage and concomitantly treated with venlafaxine for 19 days. Depression severity was evaluated at four visits. Plasma concentrations of venlafaxine and its major metabolites O-desmethylvenlafaxine (ODV) and N-desmethylvenlafaxine (NDV) and pindolol were analysed. The ratio of ODV/venlafaxine was calculated. A low ratio corresponds to patients being poor metabolizers and a high ratio corresponds to patients being extensive metabolizers.

RESULTS

No statistically significant difference in depression outcome was found between treatment groups. A statistically significant effect was, however, found of the ratio of ODV/venlafaxine on depression outcome, showing an augmenting effect of pindolol in patients with a low ratio, and the reverse in patients with a high ratio.

CONCLUSION

The differential effect of pindolol, on depression outcome, in patients with varying degrees of venlafaxine metabolism into ODV, corresponds to patients being poor or extensive metabolizers of venlafaxine. From this finding, we conclude that only patients who are poor metabolizers of venlafaxine might benefit from pindolol augmentation. This mechanism might explain some of the variability of outcome in pindolol augmentation studies.

Slowed relaxation and preserved maximal force in soleus muscles of mice with targeted disruption of the Serca2 gene in skeletal muscle

Sarcoplasmic reticulum Ca(2+) ATPases (SERCAs) play a major role in muscle contractility by pumping Ca(2+) from the cytosol into the sarcoplasmic reticulum (SR) Ca(2+) store, allowing muscle relaxation and refilling of the SR with releasable Ca(2+). Decreased SERCA function has been shown to result in impaired muscle function and disease in human and animal models. In this study, we present a new mouse model with targeted disruption of the Serca2 gene in skeletal muscle (skKO) to investigate the functional consequences of reduced SERCA2 expression in skeletal muscle. SkKO mice were viable and basic muscle structure was intact. SERCA2 abundance was reduced in multiple muscles, and by as much as 95% in soleus muscle, having the highest content of slow-twitch fibres (40%). The Ca(2+) uptake rate was significantly reduced in SR vesicles in total homogenates. We did not find any compensatory increase in SERCA1 or SERCA3 abundance, or altered expression of several other Ca(2+)-handling proteins. Ultrastructural analysis revealed generally well-preserved muscle morphology, but a reduced volume of the longitudinal SR. In contracting soleus muscle in vitro preparations, skKO muscles were able to fully relax, but with a significantly slowed relaxation time compared to controls. Surprisingly, the maximal force and contraction rate were preserved, suggesting that skKO slow-twitch fibres may be able to contribute to the total muscle force despite loss of SERCA2 protein. Thus it is possible that SERCA-independent mechanisms can contribute to muscle contractile function.

Transcranial low voltage pulsed electromagnetic fields in patients with treatment-resistant depression

BACKGROUND

Approximately 30% of patients with depression are resistant to antidepressant drugs. Repetitive transcranial magnetic stimulation (rTMS) has been found effective in combination with antidepressants in this patient group. The aim of this study was to evaluate the antidepressant effect of a new principle using low-intensity transcranially applied pulsed electromagnetic fields (T-PEMF) in combination with antidepressants in patients with treatment-resistant depression.

METHODS

This was a sham-controlled double-blind study comparing 5 weeks of active or sham T-PEMF in patients with treatment-resistant major depression. The antidepressant treatment, to which patients had been resistant, was unchanged 4 weeks before and during the study period. Weekly assessments were performed using both clinician-rated and patient-rated scales. The T-PEMF equipment was designed as a helmet containing seven separate coils located over the skull that generated an electrical field in tissue with orders of magnitude weaker than those generated by rTMS equipment.

RESULTS

Patients on active T-PEMF showed a clinically and statistically significant better outcome than patients treated with sham T-PEMF, with an onset of action within the first weeks of therapy. Effect size on the Hamilton 17-item Depression Rating Scale was .62 (95% confidence interval .21-1.02). Treatment-emergent side effects were few and mild.

CONCLUSION

The T-PEMF treatment was superior to sham treatment in patients with treatment-resistant depression. Few side effects were observed. Mechanism of the antidepressant action, in light of the known effects of PEMF stimulation to the brain, is discussed.

High cortisol awakening response is associated with an impairment of the effect of bright light therapy

OBJECTIVE

We investigated the predictive validity of the cortisol awakening response (CAR) in patients with non-seasonal major depression.

METHOD

Patients were treated with sertraline in combination with bright or dim light therapy for a 5-week period. Saliva cortisol levels were measured in 63 patients, as an awakening profile, before medication and light therapy started. The CAR was calculated by using three time-points: awakening and 20 and 60 min after awakening.

RESULTS

Patients with low CAR had a very substantial effect of bright light therapy compared with dim light therapy, whereas patients with a high CAR had no effect of bright light therapy compared with dim light therapy.

CONCLUSION

High CAR was associated with an impairment of the effect of bright light therapy. This result raises the question of whether bright light acts through a mechanism different from that of antidepressants.

A validation analysis of two self-reported HAM-D6 versions

OBJECTIVE

The six items of the clinician-administrated Hamilton Depression Scale (HAM-D(6)) cover the core items of depressive states reflecting the antidepressive effect of medication. In this study, the two self-reported versions of the HAM-D(6) have been psychometrically validated to ensure the unidimensionality of this administration form in patients with mild-to-moderate depression.

METHOD

The item response theory analysis of Mokken was used to test the unidimensionality of both the Interactive Voice Recording System (IVRS) version of the HAM-D(6) and a paper-and-pencil self-reported version (S-HAM-D(6)). Patients with typical major depression and with seasonal affective disorder were included.

RESULTS

The Mokken analysis showed that the two self-reported versions of the HAM-D(6) obtained coefficients of homogeneity above 0.40, similar to the clinician-rated HAM-D(6) and thus implying unidimensionality. By contrast, the full HAM-D(17) versions (self-reported as well as clinician-rated) obtained coefficients of homogeneity below 0.40, implying that the HAM-D(17) is a multidimensional scale.

CONCLUSION

The analysis show that both the IVRS version and the S-HAM-D(6) version are unidimensional self-rating scales for the measurement of depressive states.

Repetitive transcranial magnetic stimulation (rTMS) in combination with escitalopram in patients with treatment-resistant major depression: a double-blind, randomised, sham-controlled trial

BACKGROUND

The role of high-frequency rTMS over the left cortex as an add-on strategy in the treatment of major depression is still uncertain even in patients resistant to pharmacotherapy. We had planned a large sham TMS controlled study in the acute phase with a placebo-controlled relapse-prevention phase with escitalopram. However, because a recent meta-analysis showed only a small effect size of rTMS over sham TMS in the acute treatment phase of depressed patients, we decided to make an interim analysis.

METHOD

In patients with medication-resistant major depression we administered in a randomised trial 15 sessions of sham-controlled rTMS over three weeks in combination with 20 mg escitalopram daily. After the last rTMS, the patients were followed for another 9 weeks on 20 mg escitalopram daily. The antidepressant effect was measured by the HAM-D(6) as primary outcome scale.

RESULTS

A total of 45 patients with complete data were randomised so that 23 patients received sham TMS and 22 patients received active, high-frequency rTMS over the left cortex. Over the 3 weeks, the active rTMS treatment was superior to sham TMS with effect sizes on the HAM-D(6) above 0.70, which indicates not only a statistically but also a clinically significant effect. The patients had typically been through two failed antidepressant treatment attempts with non-tricyclics before inclusion in the study. Both the rTMS and escitalopram were well-tolerated.

CONCLUSION

High-frequency rTMS over the left cortex is an add-on strategy of clinical significance in combination with escitalopram in patients with major depression resistant to non-tricyclic antidepressants.

The lack of sustained effect of bright light, after discontinuation, in non-seasonal major depression

BACKGROUND

Recently accumulated evidence has demonstrated that bright-light therapy in combination with antidepressants is effective in patients with non-seasonal major depression. Whether bright light has a sustained effect after discontinuation is, however, poorly investigated.

METHOD

In this double-blind randomized study we report the results from a 4-week follow-up period in patients with major non-seasonal depression who had been treated for 5 weeks with sertraline combined with bright-light therapy or sertraline combined with dim-light therapy. At the beginning of the follow-up period the light therapy was stopped while sertraline treatment continued for 4 weeks.

RESULTS

Depression scores decreased substantially in both groups, resulting in high response and remission rates in both groups after 9 weeks of treatment. The difference in depression scores at week 5, favouring the bright-light-treated group, disappeared gradually in the 4-week follow-up period, resulting in similar end-point scores.

CONCLUSIONS

Bright light did not have a sustained effect after discontinuation. The offset of effect was complete after 4 weeks.

Adjunctive bright light in non-seasonal major depression: results from clinician-rated depression scales

OBJECTIVE

To investigate the use of bright light therapy as an adjunct treatment to sertraline in non-seasonal major depression.

METHOD

In a randomised double-blind trial, 102 patients were treated for 5 weeks with either white bright light (10 000 lux, 1 h daily) or red dim light (50 lux, 30 min daily). All patients were treated with sertraline in a fixed dose of 50 mg daily. The clinician-rated depression scales used were the Hamilton Depression Rating Scale (HAM-D17), Hamilton six-item subscale (HAM-D6), Melancholia Scale (MES) and the seven 'atypical' items from the SIGH-SAD.

RESULTS

One-hundred and two patients were included in the study. Analyses showed that the reduction in depression scores in the bright light group was statistically significantly larger than in the dim light group on all scales. The scale most sensitive at endpoint was the HAM-D(6), which includes the core symptoms of depression.

CONCLUSION

The study results support the use of bright light as an adjunct treatment to antidepressants in non-seasonal depression.

Adjunctive bright light in non-seasonal major depression: results from patient-reported symptom and well-being scales

OBJECTIVE

In this study, we tested the efficacy of bright light therapy as an adjunct to antidepressant treatment (sertraline) in patients with non-seasonal major depression.

METHOD

In a randomized double-blind controlled trial, 102 patients were treated for 5 weeks with either white bright light (10.000 lx, 1 h/day) or red dim light (50 lx, 30 min/day). All patients received sertraline in a dosage of 50 mg daily. The self-assessment scales used were the Major Depression Inventory (MDI), the Psychological General Well-Being Scale (PGWB) and the Symptom Check List (SCL-90R).

RESULTS

On all three questionnaires the score differences between baseline and endpoint were greatest in the bright light group. On the SCL-90R, the difference reached statistical significance. Results and effect sizes are compared with results from Danish national population studies applying PGWB and SCL-90R.

CONCLUSION

The results advocate the use of bright light as an adjunct treatment of non-seasonal depression.

Decreasing TSH levels in patients with Seasonal Affective Disorder (SAD) responding to 1 week of bright light therapy

BACKGROUND

Seasonal Affective Disorder (SAD) is characterised by lowered mood and atypical depressive symptoms such as hypersomnia, weight gain and fatigue. These symptoms seem associated with hypothyroidism, but the results of evaluations of the thyroid function in SAD patients have been conflicting, most likely due to the very small number of observations.

METHODS

In total, 83 patients fulfilling the DSM-III-R criteria for SAD were treated with bright light for 1 week in an open trial. Thyroid function was evaluated by TSH (thyroid-stimulating hormone), T(4) (thyroxine) and T(3) (triiodthyronine) levels at baseline and after 1 week of bright light treatment.

RESULTS

The response rate in terms of a 50% reduction of pre-treatment scores on the Hamilton Depressions Rating Scale (HAM-D(17)) was 61%. The TSH levels in all 83 patients decreased significantly from 1.57 at baseline to 1.30 at endpoint. In the group of responders (n=52) the TSH levels decreased significantly from 1.71 to 1.37, while in the group of non-responders (n=31) the decrease in TSH levels was not statistically significant.

CONCLUSIONS

During 1 week of bright light therapy the TSH levels in SAD patients were reduced, with the highest reduction in the group of patients responding to light therapy.

The validity of the depression rating scales in discriminating between citalopram and placebo in depression recurrence in the maintenance therapy of elderly unipolar patients with major depression

The World Federation of Societies of Biological Psychiatry guidelines for treatment of unipolar major depression has recommended three depression rating scales for evaluating outcome: The Hamilton Depression Rating Scale (HAM-D), the Montgomery-Asberg Depression Rating Scale (MADRS), and the Bech-Rafaelsen Melancholia Scale (MES). In this study we evaluated the ability of these scales to differentiate between citalopram and placebo in the recurrence prevention of unipolar depression. The study is a psychometric reexamination of a trial on the efficacy of citalopram versus placebo in the maintenance therapy of elderly patients with unipolar depression. Internal validity (the Cronbach coefficient alpha, the Loevinger coefficient of homogeneity, and factor analysis) of the three scales has been examined to evaluate their unidimensionality. In the outcome analysis for depression recurrence, the conventional cutoff scores of the three scales are used. In total, 60 patients received citalopram and 61 patients received placebo in the maintenance phase of 48 weeks. The results showed that the internal validity was higher for MES and MADRS than for HAM-D. Using the MADRS, 67.2 % of the patients on placebo and 31.6 % of the patients on citalopram developed a depression recurrence (ratio 2.12); using HAM-D17, 42.6 % on placebo and 13.3 % on citalopram developed a depression recurrence (ratio 3.20); and using the MES, 34.4 % on placebo and 11.7 % on citalopram developed a depression recurrence (ratio 2.94). The conventional cutoff scores of HAM-D17 and MES for depression recurrence indicated a ratio between citalopram and placebo of around 3, while the conventional cutoff scores of MADRS for depression recurrence indicated a ratio of only around 2. In future trials on the recurrence prevention of unipolar depression, a cutoff score of 25 rather than 22 on the MADRS is recommended.

Relapse prevention by citalopram in SAD patients responding to 1 week of light therapy. A placebo-controlled study

OBJECTIVE

We have tested the relapse-preventive effect of citalopram when compared with placebo in 282 patients with Seasonal Affective Disorder (SAD) responding to 1 week of light therapy.

METHOD

The response rate to 1-week light therapy and relapse during the continuation phase of 15 weeks were assessed by use of the Hamilton Depression Rating Scale (HAM-D17), the six-item subscale (HAM-D6), the Melancholia Scale (MES), and the combined HAM-D/SIGH-SAD.

RESULTS

The response rate to light therapy was 62.5% on the HAM-D17 and the HAM-D6, 56.1% on the HAM-D/SIGH-SAD, 52.8% on the MES. In the continuation phase, citalopram was found superior to placebo on all scales, but the difference was only of statistical significance on the HAM-D6 and the MES. Mean citalopram dose was 26.3 mg.

CONCLUSION

Light therapy was found to have and early onset of action. On the HAM-D6 and the MES citalopram significantly reduced the relapse rate in the continuation phase.

Transcriptional analysis of the genetic elements involved in the lysogeny/lysis switch in the temperate lactococcal bacteriophage phiLC3, and identification of the Cro-like protein ORF76

A transcriptional analysis of the lysogeny-related genes of the temperate bacteriophage Lactococcus lactis phiLC3 was performed using Northern blot hybridization during lysogeny and lytic infection by the phage. The lysogeny-related gene cluster was found to contain four promoters (P(1), P(2), Pint and P(173)), while the P(87) promoter directed transcription of orf80 and the putative gene orf87, which are located between the integrase gene and the cell lysis genes. The start sites of the transcripts were determined by primer extension. The divergently oriented lysogenic P(1) and lytic P(2) promoters located in the genetic switch region are responsible for transcription of orf286 which encodes the phage repressor, and the genes orf63 - orf76 - orf236 - orf110 - orf82 - orf57, respectively, while orf173 is transcribed from P(173). orf76 was identified as the gene encoding the Cro-like protein of phiLC3, and it was shown that ORF76 is able to bind specifically to the genetic switch region, albeit with lower affinity than does the phage repressor ORF286. ORF76 also competed with ORF286 for binding to this region. The functionality of P(1) and P(2), and their regulation by ORF286 and ORF76, was investigated using a reporter gene. In general, P(2) was a stronger promoter than P(1), but expression from both promoters, especially P(2), was regulated and modulated by flanking sequences and the presence of orf286 and orf76. ORF286 and ORF76 were both able to repress transcription from P(1) and P(2), while ORF286 was able to stimulate its own synthesis by tenfold. This work reveals the complex interplay between the regulatory elements that control the genetic switch between lysis and lysogeny in phiLC3 and other temperate phages of Lactococcus.

A double-blind, placebo-controlled study of sertraline in the prevention of depression in stroke patients

The authors tested the effect of sertraline in the prevention of poststroke depression. After experiencing an acute ischemic stroke, nondepressed patients (N=137) were randomly assigned to 12 months of double-blind treatment with either sertraline (N=70) or placebo (N=67). Kaplan-Meier analysis showed sertraline to have significantly superior prophylactic efficacy compared with placebo. Two definitions of clinical depression were used: total score >18 on the HAM-D(17) and score >or=9 on the HAM-D(6). Approximately 10% of the sertraline-treated group developed depression according to either definition, whereas 30% developed depression in the placebo group. On the HAM-D(6) the superiority of sertraline to placebo was demonstrated already after 6 weeks of therapy. Treatment was well tolerated; patients treated with sertraline experienced significantly fewer adverse events.

Platelet serotonin transporter in stroke patients

OBJECTIVES

Post-stroke depression can be treated with serotonin transport inhibitors suggesting a role for the serotonin system in these patients. The number of platelet serotonin transporters in stroke patients and in control subjects have been measured in this study.

MATERIAL AND METHODS

Newly admitted stroke patients who did develop or who did not develop a post-stroke depression, non-acute patients who previously had had a stroke and control subjects were compared. The number of platelet serotonin transporters was analysed by ligand binding methodology.

RESULTS

The number of platelet serotonin transporters was low shortly after a stroke compared with normal subjects; no difference was found between the stroke patients who developed a post-stroke depression and those who did not.

CONCLUSION

A low number of platelet serotonin transporters may be a non-specific state marker for a condition as acute stroke.

Efficacy of citalopram in the prevention of recurrent depression in elderly patients: placebo-controlled study of maintenance therapy

BACKGROUND

The highly recurrent nature of major depression in the young and the elderly warrants long-term antidepressant treatment.

AIMS

To compare the prophylactic efficacy of citalopram and placebo in elderly patients; to evaluate long-term tolerability of citalopram.

METHOD

Out-patients, > or =65 years, with unipolar major depression (DSM-IV: 296.2 x or 296.3 x) and Montgomery-Asberg Depression Rating Scale score > or =22 were treated with citalopram 20-40 mg for 8 weeks. Responders continued on their final fixed dose of citalopram for 16 weeks before randomisation to double-blind treatment with citalopram or placebo for at least 48 weeks.

RESULTS

Nineteen of the 60 patients using citalopram v. 41 of the 61 patients using placebo had recurrence. Time to recurrence was significantly different between citalopram- and placebo-patients, in favour of citalopram (log-rank test, P<0.0001). Long-term treatment was well tolerated.

CONCLUSIONS

Long-term treatment with citalopram is effective in preventing recurrence of depression in the elderly and is well tolerated.

Social Adaptation Self-evaluation Scale (SASS): Psychometric analysis as outcome measure in the treatment of patients with major depression in the remission phase

INTRODUCTION

To carry out a psychometric analysis of the Social Adaptation Self-evaluation Scale (SASS), which has been found very promising during first experiences with it in the treatment of depression.

METHOD

Patients in the remission phase during treatment for a major depressive episode completed the SASS over a period of 12 weeks, with monthly assessments. For comparison, the Hamilton Depression Scale with the Melancholia Scale (HAM-D/MES) was used as well as a self-reporting questionnaire, the Major Depression Inventory (MDI). In the psychometric analysis both classical tests (e.g. principal component analysis) and modern tests (Mokken analysis with the Loevinger coefficient of homogeneity) were applied.

RESULTS

The SASS scale with its 21 items was found to contain at least three factors, of which the first was a general factor; this however explained less than 50% of the variance. A subscale containing the six items with the highest factor loadings was found to be a unidimensional scale. This subscale showed a much higher responsiveness than the total SASS. However, both SASS scales were found to have a lower responsiveness than the Major Depression Inventory (MDI) during the first weeks of treatment.

CONCLUSION

The SASS was found to be a multidimensional scale. However, a six-items subscale (covering items with the highest loadings on the first use) was shown to be a unidimensional scale and to have a greater responsiveness than the total SASS, but still lower than the MDI. (Int J Psych Clin Pract 2002; 6: 141-146).

Analysis of a regulator involved in the genetic switch between lysis and lysogeny of the temperate Lactococcus lactis phage φLC3

Sequencing of a 1.3-kb fragment of DNA from the temperate Lactococceus lactis subsp. cremoris phage phiLC3 revealed a pair of two divergently oriented ORFs, orf63 and orf286. The deduced amino acid sequence of the product of orf286 showed extensive homology to those of repressors of the temperate lactococcal phages rlt, Tuc2009 and BK5-T. A mutant with an amber mutation in orf286 gave rise to a clear plaque phenotype, indicating that this gene is involved in the lytic and lysogenic development of phiLC3. Gel mobility shift assays showed that the partially purified Orf286 protein bound specifically to the 224-bp intergenic region located between orf286 and orf63, and further characterization by DNase I footprinting analysis revealed that Orf286 protects two distinct sites within this region. Sequence analysis of the intergenic region revealed two putative, divergently oriented promoters, P1 and P2; orf286 and orf63 are probably transcribed from P1 and P2, respectively. In vivo analyses of P1 and P2 using beta-galactosidase as a reporter enzyme in L. lactis showed that transcription from P1 was repressed while transcription from P2 was stimulated in the presence of the Orf286 protein. These results suggest a complex role for the Orf286 protein in regulating the genetic switch between lytic and lysogenic growth of phiLC3.

The life cycles of the temperate lactococcal bacteriophage phiLC3 monitored by a quantitative PCR method

We present here a new and general approach for monitoring the life cycles of temperate bacteriophages which establish lysogeny by inserting their genomes site-specifically into the bacterial host chromosome. The method is based on quantitative amplification of specific DNA sites involved in various cut-and-join events during the life cycles of the phages (i.e. the cos, attP, attB, attL and attR sites) with the use of sequence-specific primers. By comparing the amounts of these specific DNA sites at different intervals, we were able to follow the development of the lytic and lysogenic life cycles of the temperate lactococcal bacteriophage phiLC3 after infection of its bacterial host Lactococcus lactis ssp. cremoris IMN-C18.

Relapse prevention by means of paroxetine in ECT-treated patients with major depression: a comparison with imipramine and placebo in medium-term continuation therapy

In-patients with severe major depression were treated in the acute phase with electroconvulsive therapy (ECT) in combination with antidepressants. The drug treatment consisted of two randomized trials which were both extended into the post-ECT continuation phase. Patients with electrocardiological impairment were randomized to either 30 mg paroxetine daily or placebo under blind conditions. Patients without electrocardiological impairment were randomized to either 30 mg paroxetine daily or 150 mg imipramine daily. There was a high level of agreement between the Hamilton Depression Scale and the Melancholia Scale, demonstrating that the patients treated with ECT plus imipramine in the acute phase showed greater symptom reduction than those treated with ECT plus paroxetine. However, in the post-ECT phase paroxetine was superior to both imipramine and placebo in preventing relapse. Thus in the post-ECT phase 65% of the placebo-treated patients relapsed, compared to 30% of the imipramine-treated patients and 10% of the paroxetine-treated patients. The psychometric analysis of the Melancholia Scale in the continuation or post-ECT phase showed that relapsing patients displayed a pattern with lack of interests, impaired concentration, depressed mood and anxiety among the less severe symptoms (first-compartment symptoms). In other words, these symptoms represent the gate to full-blown depression (second-compartment symptoms). Serotonin-selective antidepressants such as paroxetine appear to be more effective in controlling the first-compartment symptoms.

A definite and a semidefinite questionnaire version of the Hamilton/melancholia (HDS/MES) scale

A definite (anchored) and a semidefinite (semi-anchored) questionnaire version of the Hamilton Depression Rating Scale (HDS) and the Bech-Rafaelsen Melancholia Scale (MES) were compared with the HDS/MES by observer-rating and self-rating of 24 patients fulfilling the DSM-3R criteria for major depressive disorder. Both types of questionnaire showed substantial agreement with the observer scale from which they were derived. The sum scores were for the definite questionnaires and the corresponding observer scales closely similar whereas the sum scores of the semidefinite questionnaires were significantly higher than the sum scores of the corresponding observer scales. These results indicate that patients' 'halo' effect may be avoided by using definite scaling criteria for self-rating. Thus, of the two versions of questionnaires the definite versions are recommended.

Platelet paroxetine binding in depressed and nondepressed chronic pain patients

Analysis of 3H-paroxetine binding was used to determine the number of serotonin transporters in platelet membranes of chronic pain patients and controls. The pain patients who also suffered from depression in addition to the pain had significantly more serotonin transporters than the controls.