Comparison of Conventional versus Steerable-Catheter Guided Coronary Sinus Lead Positioning in Patients Undergoing Cardiac Resynchronization Device Implantation

Objectives

The aim of this study was to compare conventional versus steerable catheter guided coronary sinus (CS) cannulation in patients with advanced heart failure undergoing cardiac resynchronization therapy (CRT).

Background

Steerable catheter guided coronary sinus cannulation could reduce fluoroscopy time and contrast medium use during CRT implantation.

Methods

176 consecutive patients with ischemic and non-ischemic heart failure undergoing CRT implantation from January 2008 to December 2012 at the University Hospital of Cologne were identified. During the study period two concurrent CS cannulation techniques were used: standard CS cannulation technique (standard-group, n = 113) and CS cannulation using a steerable electrophysiology (EP) catheter (EPCath-group, n = 63). Propensity-score matched pairs of conventional and EP-catheter guided CS cannulation made up the study population (n = 59 pairs). Primary endpoints were total fluoroscopy time and contrast medium amount used during procedure.

Results

The total fluoroscopy time was 30.9 min (interquartile range (IQR), 19.9–44.0 min) in the standard-group and 23.4 min (IQR, 14.2-34-2 min) in the EPCath-group (p = 0.011). More contrast medium was used in the standard-group (60.0 ml, IQR, 30.0–100 ml) compared to 25.0 ml (IQR, 20.0–50.0 ml) in the EPCath-group (P<0.001).

Conclusions

Use of steerable EP catheter was associated with significant reduction of fluoroscopy time and contrast medium use in patients undergoing CRT implantation.     

Effects of Selenium and Vitamin E,in Addıtıon to Melatonin,Against Oxidative Stress Caused by Cadmium in Rats

The present study was carried to evaluate the protective effects of melatonin alone and vitamin E with selenium combination against high dose cadmium-induced oxidative stress in rats. The control group received subcutanous physiological saline. The first study group administered cadmium chloride (CdCl₂) by subcutaneous injection of dose of 1 mg/kg. The second study group administered cadmium plus vitamin E with selenium (1 mg/kg sodium selenite with 60 mg/kg vitamin E); the third study group administered cadmium plus 10 mg/kg melatonin (MLT); the fourth study group administered CdCl₂ plus a combination of melatonin in addition to vitamin E and selenium for a month. Determination levels of plasma malondialdehyde (MDA), glutathione peroxidase (GSH-Px), blood superoxide dismutase (SOD), creatinine alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), blood urea nitrogen (BUN), and urea were measured in serum. In only CdCl₂ administered group, the MDA, creatinine, ALT, AST, ALP, and urea levels in the serum were significantly higher than the control group (p < 0.05). Whereas in all other groups, this values were significantly lower than the only CdCl₂ administered group (p < 0.05). Erythrocytes GSH-Px, serum SOD activities of only CdCl₂ received group were significantly lower than the control group (p < 0.05). In conclusion, vitamin E + Se, melatonin and vitamin E, and Se, in addition to MLT combinations, had protective effects against high dose cadmium-induced oxidative damage.     

Mutations in autism susceptibility candidate 2 (AUTS2) in patients with mental retardation

We report on three unrelated mentally disabled patients, each carrying a de novo balanced translocation that truncates the autism susceptibility candidate 2 (AUTS2) gene at 7q11.2. One of our patients shows relatively mild mental retardation; the other two display more profound disorders. One patient is also physically disabled, exhibiting urogenital and limb malformations in addition to severe mental retardation. The function of AUTS2 is presently unknown, but it has been shown to be disrupted in monozygotic twins with autism and mental retardation, both carrying a translocation t(7;20)(q11.2;p11.2) (de la Barra et al. in Rev Chil Pediatr 57:549–554, 1986; Sultana et al. in Genomics 80:129–134, 2002). Given the overlap of this autism/mental retardation (MR) phenotype and the MR-associated disorders in our patients, together with the fact that mapping of the additional autosomal breakpoints involved did not disclose obvious candidate disease genes, we ascertain with this study that AUTS2 mutations are clearly linked to autosomal dominant mental retardation.     

Comamonas testosteroni bacteremia in a patient with perforated acute appendicitis. Short communication

Comamonas testosteroni is an uncommon isolate in the clinical laboratory as a human pathogen. C. testosteroni most commonly emerges in abdominal pathologies especially in perforated appendicitis. In Turkey we report first time a case of bacteremia due to this organism, in a 22-year-old man with perforated acute appendicitis. The organism was shown to be susceptible to routine antibiotics so it was easily eliminated even after having caused a bacteremia.     

PHOTOSYSTEM II PROTEIN33, a Protein Conserved in the Plastid Lineage,Is Associated with the Chloroplast Thylakoid Membrane and Provides Stability to Photosystem II Supercomplexes in Arabidopsis

Photosystem II (PSII) is a multiprotein complex that catalyzes the light-driven water-splitting reactions of oxygenic photosynthesis. Light absorption by PSII leads to the production of excited states and reactive oxygen species that can cause damage to this complex. Here, we describe Arabidopsis (Arabidopsis thaliana) At1g71500, which encodes a previously uncharacterized protein that is a PSII auxiliary core protein and hence is named PHOTOSYSTEM II PROTEIN33 (PSB33). We present evidence that PSB33 functions in the maintenance of PSII-light-harvesting complex II (LHCII) supercomplex organization. PSB33 encodes a protein with a chloroplast transit peptide and one transmembrane segment. In silico analysis of PSB33 revealed a light-harvesting complex-binding motif within the transmembrane segment and a large surface-exposed head domain. Biochemical analysis of PSII complexes further indicates that PSB33 is an integral membrane protein located in the vicinity of LHCII and the PSII CP43 reaction center protein. Phenotypic characterization of mutants lacking PSB33 revealed reduced amounts of PSII-LHCII supercomplexes, very low state transition, and a lower capacity for nonphotochemical quenching, leading to increased photosensitivity in the mutant plants under light stress. Taken together, these results suggest a role for PSB33 in regulating and optimizing photosynthesis in response to changing light levels.PSII is a multiprotein complex in plants with 31 identified polypeptides (Wegener et al., 2011; Pagliano et al., 2013). It is associated with an extrinsic trimeric light-harvesting complex (LHC), forming the PSII-LHCII supercomplex. The PSII complex performs a remarkable biochemical reaction, the oxidation of water using light energy from the sun, which profoundly contributes to the overall biomass accumulation in the biosphere (Barber et al., 2004). Consequently, the stability and functional integrity of the PSII-LHCII supercomplex is crucially important for photosynthetic function. The energy of a photon, either absorbed directly by PSII or indirectly via energy transfer from adjacent antenna chlorophyll (Chl) molecules, excites the PSII reaction center P680. The excited state, P680*, can transfer an electron to pheophytin, producing the most powerful oxidant known in biology, P680⁺, which can remove electrons from water. Excessive input of excitation energy into PSII saturates the electron transfer system and causes either acceptor or donor site limitation in the complex. This results in increased production of reactive oxygen species (ROS): singlet oxygen at the PSII donor side and superoxide at the acceptor side (Munné-Bosch et al., 2013). Several protective mechanisms have been documented that decrease the production of singlet oxygen at the PSII donor side in photosynthetic eukaryotes. Notably, reducing energy transfer from LHC to PSII via nonphotochemical quenching (NPQ) is a key avoidance mechanism (Ruban and Murchie, 2012).Despite years of intensive study of PSII structure and function, new proteins that are associated with the PSII complex continue to be discovered, including an increasing number involved in the stability and organization of PSII-LHCII supercomplexes (García-Cerdán et al., 2011; Lu et al., 2011a; Wegener et al., 2011). Two complementary approaches (Merchant et al., 2007; Lu et al., 2008, 2011b; Ajjawi et al., 2010) that utilize phylogenomics (GreenCut) and large-scale phenotypic mutant screening (Chloroplast 2010 Project; http://www.plastid.msu.edu/) were employed by our groups to discover novel plant proteins with roles in photosynthesis. GreenCut identifies proteins found only in photosynthetic organisms, and it is likely that many of them are involved in biochemical processes associated with the structure, assembly, or function of the photosynthetic apparatus and the chloroplast that houses it (Merchant et al., 2007; Karpowicz et al., 2011). The Chloroplast 2010 Project was a large-scale reverse-genetic mutant screen in which thousands of homozygous Arabidopsis (Arabidopsis thaliana) transfer DNA (T-DNA) insertion lines were analyzed for defects in the rise and decay kinetics of Chl fluorescence (Lu et al., 2008, 2011a, 2011b; Ajjawi et al., 2010).The GreenCut and Chloroplast 2010 approaches both identified the Arabidopsis At1g71500 locus as encoding a protein of unknown function with potential relevance to photosynthesis. In this work, we demonstrate that plant lines carrying three independent mutations at this locus display severe light-induced photoinhibition due to a less stable supramolecular organization of PSII. Biochemical analyses revealed that this protein is associated with PSII complexes, and since the last described PSII protein was called PHOTOSYSTEM II PROTEIN32 (PSB32), we named the gene PSB33. The nuclear genome-encoded PSB33 is predicted to have a chloroplast transit peptide and a transmembrane domain. The biochemical analyses presented below indicate that PSB33 is required for the proper interaction and stability of PSII-LHCII supercomplexes and, in turn, in regulating photosynthesis in response to fluctuating light levels.     

Light acclimation involves dynamic re‐organization of the pigment–protein megacomplexes in non‐appressed thylakoid domains

Thylakoid energy metabolism is crucial for plant growth, development and acclimation. Non‐appressed thylakoids harbor several high molecular mass pigment–protein megacomplexes that have flexible compositions depending upon the environmental cues. This composition is important for dynamic energy balancing in photosystems (PS) I and II. We analysed the megacomplexes of Arabidopsis wild type (WT) plants and of several thylakoid regulatory mutants. The stn7 mutant, which is defective in phosphorylation of the light‐harvesting complex (LHC) II, possessed a megacomplex composition that was strikingly different from that of the WT. Of the nine megacomplexes in total for the non‐appressed thylakoids, the largest megacomplex in particular was less abundant in the stn7 mutant under standard growth conditions. This megacomplex contains both PSI and PSII and was recently shown to allow energy spillover between PSII and PSI (Nat. Commun., 6, 2015, 6675). The dynamics of the megacomplex composition was addressed by exposing plants to different light conditions prior to thylakoid isolation. The megacomplex pattern in the WT was highly dynamic. Under darkness or far red light it showed low levels of LHCII phosphorylation and resembled the stn7 pattern; under low light, which triggers LHCII phosphorylation, it resembled that of the tap38/pph1 phosphatase mutant. In contrast, solubilization of the entire thylakoid network with dodecyl maltoside, which efficiently solubilizes pigment–protein complexes from all thylakoid compartments, revealed that the pigment–protein composition remained stable despite the changing light conditions or mutations that affected LHCII (de)phosphorylation. We conclude that the composition of pigment–protein megacomplexes specifically in non‐appressed thylakoids undergoes redox‐dependent changes, thus facilitating maintenance of the excitation balance between the two photosystems upon changes in light conditions.