Systematic review on left atrial appendage closure with the LAmbre device in patients with non-valvular atrial fibrillation.

BACKGROUND: Percutaneous closure (LAAC) of the left atrial appendage (LAA) is an efficacious preventive procedure for patients with non-valvular atrial fibrillation (NVAF) and considerable bleeding risk. We sought to systematically review the available LAAC data on the novel occluder device LAmbre™. METHODS: For this systematic review, a search of the literature was conducted by 3 independent reviewers, reporting the safety and therapeutic success of LAAC in patients being treated with a LAmbre™. Publications reporting the safety and therapeutic success of LAAC using LAmbre™ in n > 5 patients were included. RESULTS: The literature search retrieved n = 10 publications, encompassing n = 403 NVAF patients treated with a LAmbre™ LAAC, with relevant data regarding safety and therapeutic success of the procedure. The mean CHA2DS2-VASc Score was 4.0 + 0.9, and the mean HAS-BLED score was 3.4 + 0.5. The implantation success was 99.7%, with a mean procedure time of 45.4 ± 18.7 min, and a fluoroscopy time of 9.6 ± 5.9 min, and a contrast agent volume of 96.7 ± 0.7 ml. The anticoagulation regimen was switched to DAPT post procedure in the majority of the patients (96.8%). Partial and full recapture were done in 45.5% and in 25.6%, respectively. Major complications were reported in 2.9%, with 0.3% mortality, 1.7% pericardial tamponade, 0.3% stroke, and 0.6% major bleeding complications; no device embolization was observed. During follow up at 6 or 12 months, major adverse cardiovascular events were reported in 3.3%: Stroke or TIA in 1.7%, thrombus formation on the device in 0.7%, and residual flow > 5 mm in 1.0%. In some publications, the favorable implantion properties of the LAmbre™ for difficult anatomies such as shallow or multilobular LAA anatomies were described. CONCLUSIONS: This systematic review on the LAmbre™ LAA-occluder including n = 403 NVAF patients demonstrates an excellent implantion success rate, promising follow-up clinical data, and favorable properties for also challenging LAA anatomies,. While its design seems to be helpful in preventing device embolization, pericardial tamponade may not be substantially reduced by the LAmbre™ as compared with other established LAAC devices. Further larger prospective multicenter registries and randomized trials are needed to scrutinize the value of the LAmbre™ compared with established LAAC devices.

Advances in the diagnosis and treatment of transthyretin amyloidosis with cardiac involvement.

Amyloidosis is caused by extracellular deposition of insoluble abnormal fibrils constituted by misfolded proteins, which can modify tissue anatomy and hinder the function of multiple organs including the heart. Amyloidosis that can affect the heart includes mostly systemic amyloidosis (amyloid light chain, AL) and transthyretin amyloidosis (ATTR). The latter can be acquired in elderly patients (ATTRwt), or be inherited in younger individuals (ATTRm). The diagnosis is demanding given the high phenotypic heterogeneity of the disease. Therefore, "red flags," which are suggestive features giving support to diagnostic suspicion, are extremely valuable. However, the lack of broad awareness among clinicians represents a major obstacle for early diagnosis and treatment of ATTR. Furthermore, recent implementation of noninvasive diagnostic techniques has revisited the need for endomyocardial biopsy (EMB). In fact, unlike AL amyloidosis, which requires tissue confirmation and typing for diagnosis, ATTR can now be diagnosed noninvasively with the combination of bone scintigraphy and the absence of a monoclonal protein. Securing the correct diagnosis is pivotal for the newly available therapeutic options targeting both ATTRm and ATTRwt, and are directed to either stabilization of the abnormal protein or the reduction of the production of transthyretin. The purpose of this article is to review the contemporary aspects of diagnosis and management of transthyretin amyloidosis with cardiac involvement, summarizing also the recent therapeutic advances with tafamidis, patisiran, and inotersen.

PARP-1 expression and activity in primary human lung cells.

Activation of poly(ADP-ribose) polymerase-1 (PARP-1) in response to DNA damage is an important mechanism to keep homeostasis or to trigger apoptosis. The expression and function of (PARP-1) was studied in primary cells cultured from human lung. Normal human bronchial epithelial cells (NHBEC) and peripheral lung cells (PLC) from lung cancer patients were grown as explant cultures and were followed over a period of 12 weeks. PARP-1 protein was expressed in all explant cultures from bronchial epithelium. The levels of PARP protein differed between individuals by a factor of 2.3 in the first explant. Three cases were followed for more than 100 days. The expression levels varied intra-individually by a factor of 1.3-1.4 over this time period. PARP-1 activity was determined immunohistochemically after induction of DNA damage with H(2)O(2) (0.05-0.3 mM, 5 min). The fluorescence signal for ADP-ribose polymers attached to chromatin proteins correlated well with the concentration of H(2)O(2). PARP-1 activity differed by a factor of 3.1 in NHBECs obtained from the first generation of explants from 11 cases. PARP-1 activity is present in NHBECs until the 8th and in PLCs until the 12th week and declined to about half of the start level. Primary cultures of NHBECs and PLC are suitable to study the effect of external factors on PARP-1 expression and function.

Arachidonic acid pathway activates multidrug resistance related protein in cultured human lung cells.

Primary cultures of human lung cells can serve as a model system to study the mechanisms underlying the effects of irritants in air and to get a deeper insight into the (patho)physiological roles of the xenobiotic detoxification systems. For 99 human lung cancer cases the culture duration for bronchial epithelium and peripheral lung cells (PLC) are given in term of generations and weeks. Using this system, we investigated whether and how prostaglandins (PG) modify multidrug resistance related protein (MRP) function in normal human lung cells. PGF2alpha had no effect on MRP function, whereas PGE2 induced MRP activity in cultured NHBECs. The transport activity study of MRP in NHBEC, PLC, and A549 under the effect of exogenously supplied PGF2alpha (10 microM, 1 day) using single cell fluorimetry revealed no alteration in transport activity of MRP. PG concentrations were within the physiological range. COX I and II inhibitors indomethacin (5, 10 microM) and celecoxib (5, 10 microM) could substantially decrease the transport activity of MRP in NHBEC, PLC, and A549 in 1- and 4-day trials. Prostaglandin E2 did not change cadmium-induced caspase 3/7 activation in NHBECs and had no own effect on caspase 3/7 activity. Cadmium chloride (5, 10 microM) was an effective inducer of caspase 3/7 activation in NHBECs with a fivefold and ninefold rise of activity. In primary human lung cells arachidonic acid activates MRP transport function only in primary epithelial lung cells by prostaglandin E2 but not by F2alpha mediated pathways and this effect needs some time to develop.

Non-destructive micromethod for MRP1 functional assay in human lung tumor cells.

Defense against toxic endo- and xenobiotics is a major concern of all living species and ABC transporters play a vital role in this defense system. Multidrug resistance associated proteins 1 (MRP1) is a cellular detoxifying factor supposed to transport a wide range of compounds across cell membranes either as GSH conjugates or as co-transport accompanying glutathione transposition. The cellular localization of MRP1 is a determining factor whether the transport function can take place. In this study we have undertaken experiments on the transport activity of MRP1 in cultured human lung tumor cells in order to check whether MRP1 is expressed as a functionally active protein. For this purpose we have adapted a quantitative fluorescence imaging assay to conditions where a small number of attached cells should be repeatedly measured by a non-destructive method. In cultured A549, H358 and H322 cells MRP1 is located in the cell membrane as observed by immunocytochemistry. Efflux of 5,6-carboxy-2'-7'-dichloro-fluorescein (CDF) from lung cells was sensitive toward the MRP1 inhibitor MK571 while verapamil had no effect. On the other hand, efflux of Rhodamin 123, a Pgp-glycoprotein substrate, from lung cells reacted to inhibition by verapamil, while MK571 had no effect. Modulation of glutathion content of lung cells by N-acetyl cystein and buthionine sulfoximine shifted CDF efflux toward higher or lower rates, respectively. These experiments confirm that MRP1 function can be followed in the attached cells in vitro under non-toxic concentrations of the substrates without the need to harvest and destroy the cells.

Expression of lung resistance-related protein, LRP, and multidrug resistance-related protein, MRP1, in normal human lung cells in long-term cultures.

Transport processes form part of the body's defense mechanism, and they determine the intracellular levels of many endogenous and exogenous compounds. The multidrug resistance-related protein MRP1 and the lung resistance-related protein LRP are associated with drug resistance against chemotherapeutics; they protect cells against toxic compounds. There is much experimental evidence to suggest that both of these transporter proteins serve important physiological functions. The expression of LRP and MRP1 was studied in normal human bronchial epithelial cells (NHBEC) and peripheral lung cells (PLC) obtained from explant cultures from morphologically-normal human lung tissue taken from patients with lung cancer. LRP (mRNA and protein) was detected in the cells of the bronchi as well as the peripheral lung with low (a factor of 2.6) inter-individual variation in the first generation. No significant alterations were noted for LRP within three-to-four generations in the same patient. LRP expression was not substantially different between cultures from different topographic regions of the human lung. MRP1 protein and MRP1 mRNA could also be detected in all of the NHBEC and PLC cultures studied, but with substantially higher (a factor of 7.7) intra-individual variation in the first generation than for LRP. MRP expression was the same for bronchial cells and PLC when the material was obtained from both sites. The level of mRNA for MRP1 was, in general, less stable than that for LRP. In multigeneration explant cultures, the levels of LRP mRNA and protein and MRP1 protein did not fluctuate greatly, but the level of MRP1 mRNA dropped to about 25% of the reference value within four generations (after about 8-10 weeks of culture). In one case, NHBEC subpassages were followed over a period of 20 weeks. In this system MRP mRNA levels increased by more than threefold, while levels of MRP1 protein and LRP mRNA and protein were expressed at almost constant rates.

Immuno-histochemical detection of MRPs in human lung cells in culture.

The transport of molecules across membranes is an essential function of all living organisms and a large number of specific transporters have evolved to carry out this function. The largest transporter gene family is the ATP-binding cassette (ABC) transporter superfamily. The multidrug resistance-associated protein (MRP) family is comprised of nine related ABC transporters. The intra-cellular distribution of the different MRP isoforms in relation to their physiological and non physiological function is still a point of discussion. For this purpose we used normal human lung cells (bronchial epithelial cells, NHBEC, and peripheral lung cells, PLC) as well as tumor cell cultures as test tools to investigate the intracelluar localization of these proteins under classical culture conditions and under air-liquid interface by means of indirect fluorescence microscopy. Characterization of the cultured cells as lung epithelial cells was performed by means of immuno-histochemical analysis. MRP1 and MRP3 were localised to the cellular membrane in all tested lung cell types. In contrast to that MRP2, MRP4 and MRP5 could be described as intracellular proteins in NHBEC and PLC. All MRP1-MRP5 isoforms could be characterized in A549 tumor cell line as membrane proteins. In order to imitate the physiological in vivo circumstances in the lung, we have established a dry/wet method (air-liquid interface) for cell cultivation so that cultured cells have the option to polarize between air and basal membrane and this might influence the distribution pattern of MRP1 and MRP2 in NHBEC. Using confocal laser scanning techniques we could show that in cells kept under dry/wet conditions MRP1 was found to be localised to baso-lateral cell regions while MRP2 was localised to all cell regions. Under classical culture conditions MRP1 was not localized to particular membrane regions and MRP2 was found to be an intracellular protein.