RF ablation of longstanding persistent atrial fibrillation in patient with familial dilated cardiomyopathy

A vicious circle of interactions between dilated cardiomyopathy and longstanding persistent AF/AFL may cause symptoms of advanced congestive heart failure. In a 31-year-old patient with diagnosis of familial dilated cardiomyopathy and permanent AF lasting for five years, gradually decreased left ventricular ejection fraction (LVEF) and increased diameter of heart chambers - left ventricular diastolic dimension (LVdD) 7.7 cm, left atrium (LA) 5.4 cm, and LVEF 15% were noted. Pharmacological treatment was ineffective Successful RF ablation of AF/AFL substrate (CTI block, PVs isolation, CFAE ablation, roof and MIG line, CS applications) reversed symptoms of significant heart remodeling (LVdD 5.9 cm, LA 4.3 cm, LVEF 50%).     

Infective endocarditis--still a great challenge. Two case reports

We present two patients with aortic valve disease who developed acute infective endocarditis. In both patients the disease started with infection of the upper respiratory tract. The patients were treated with antibiotics due to pneumonia. The diagnosis of infective endocarditis was established 4 months and 9 weeks after the onset of infection. The first patient died whereas the second underwent successful aortic valve replacement.     

Disturbed right ventricular ejection pattern as a new Doppler echocardiographic sign of acute pulmonary embolism

Transthoracic echocardiography (TTE) is frequently performed in patients with suspected acute pulmonary embolism (APE) to search for right ventricular (RV) pressure overload. We prospectively assessed the diagnostic value of a new Doppler echocardiographic sign of APE based on the disturbed RV ejection pattern ("60/60 sign") and compared its diagnostic performances with that of the presence of RV pressure overload, as well as with "McConnell sign" based on RV regional wall motion abnormalities. We assessed 100 consecutive patients with clinical suspicion of APE, including those with previous cardiorespiratory diseases. After TTE, all of the patients underwent reference diagnostic tests for APE. The 60/60 sign required RV acceleration time of 相似文献   

Successful RF ablation of permanent VT in a patient with acute coronary syndrome treated by complex angioplasty and stent implantation

We describe a case of a 59-year-old male with permanent VT in the course of an acute coronary syndrome. Coronary angiography revealed acute occlusion of the right coronary artery. Although the underlying condition was treated by implantation of 4 stents with excellent haemodynamic effect (TIMI 3), the tachycardia continued, being refractory to drugs (amiodarone). The attempts to restore sinus rhythm by DC electrical cardioversion or transvenous pacing were unsuccessful. The patient was referred to the EP lab. A critical isthmus localised at the paraseptal region of the LV and parallel to the mitral annulus was identified. The isthmus was closed by linear RF application, resulting in VT termination. Due to impaired LV ejection fraction (<30%) the patient was scheduled for ICD implantation. During 6-week follow-up the patient remained free of arrhythmia.     

Assessment of selected B cells populations in the workers of X-ray departments

Objectives

Workers of X-ray departments are occupationally exposed to long-term low levels of ionizing radiation (LLIR), which may affect their humoral immunity. The aim of the study was to assess the influence of LLIR on the number and proportion of B cells (CD19+), B1 cells (CD5+CD19+) and memory B cells (CD27+CD19+) in peripheral blood of such workers.

Materials and Methods

In the study group of 47 X-ray departments workers and the control group consisting of 38 persons, the number and percentage of CD19+, CD5+CD19+, CD27+CD19+ cells as well as CD5+CD19+/CD19+ and CD27+CD19+/CD19+ cell ratios were assessed using flow cytometry. Additionally, the study group was divided into 2 groups by the length of employment below and over 15 years and analysis adjusted for age and smoking habit was performed.

Results

The total number of CD19+ cells showed significant increase in the group of workers in comparison with the persons from the control group, whereas the percentage of CD5+CD19+ cells as well as CD27+CD19+/CD19+ and CD5+CD19+/CD19+ cell ratios were lower. Percentage, number of CD5+CD19+ cells and CD5+CD19+/CD19+ cell ratio were significantly lower in the workers with length of employment longer than 15 years in comparison with those employed below 15 years. Moreover, we found positive associations between the number of CD19+ cells and employment as well as smoking habit, whereas the number of CD5+CD19+ cells was positively associated with cigarette smoking alone. Percentage of CD5+CD19+ cells as well as CD5+CD19+/CD19+ and CD27+CD19+/CD19+ cell ratios were negatively correlated with employment.

Conclusions

The study suggests association between the suppressive influence of low level ionizing radiation on circulating in peripheral blood, especially of B1 cells as well as of memory B cells, in workers of X-ray units, which is adverse in relation to microbiological threat.     

Changes in mineral status are associated with improvements in insulin sensitivity in obese patients following l-arginine supplementation

Purpose

The aim of this study is to evaluate the long-term influence of l-arginine intake on mineral concentration in patients with obesity and to assess the changes in lipid serum levels, fat content, and insulin resistance that result.

Methods

A randomized double-blind placebo-controlled study was conducted. 88 obese patients were randomly assigned to receive either 9 g of l-arginine or placebo daily, for 6 months. At baseline and after 6 months, selected anthropometrical measurements and blood biochemical analyses were performed and mineral levels were assessed. To assess insulin sensitivity, the gold-standard euglycemic clamp methodology was used.

Results

We found that 6 months of l-arginine supplementation resulted in significant increases in insulin sensitivity (Δ1.1 mg/kg/min, P < 0.01) and zinc levels (Δ1.5 μmol/L, P < 0.001). Moreover, a positive correlation between the change in zinc concentration in serum and the change in insulin sensitivity was observed (R = 0.80, P < 0.01). In the group of patients treated with l-arginine, a negative correlation between the change in zinc concentration in serum and the change in body fat content was noted (R = ?0.38, P < 0.05).

Conclusions

l-Arginine supplementation affects zinc status in obese patients. One beneficial influence is related to the improvements in insulin sensitivity.     

The adverse effects of marijuana use: The present state and future directions

Marijuana is recently a subject of a global debate due to potential medical application of cannabis products and the progressive legalization of its recreational use. This situation leads to the need for access to comprehensive and reliable information about the effects of marijuana intake. Our review presents the actual state of knowledge regarding acute and chronic health effects generated by recreational marijuana use. Marijuana smoking can lead to structural and functional alterations in the central nervous system. These effects are especially significant and dangerous at the prenatal, child, and adolescence periods. In contrary to a common myth, cannabis does exhibit an addictive potency, albeit not a strong one. We discuss the “cannabis gateway hypothesis,” which suggests that marijuana use can be the first step before trying more dangerous drugs. However, drawing significant conclusions is difficult due to the strong impact of confounders and often unclear relationships among studied factors, especially in the socioeconomic context. Moreover, we point to the need for the unbiased assessment of the harm generated by marijuana in comparison with other drugs.     

Polymorphisms in TS,MTHFR and ERCC1 genes as predictive markers in first-line platinum and pemetrexed therapy in NSCLC patients

Purpose

We presented retrospective analysis of up to five polymorphisms in TS, MTHFR and ERCC1 genes as molecular predictive markers for homogeneous Caucasian, non-squamous NSCLC patients treated with pemetrexed and platinum front-line chemotherapy.

Methods

The following polymorphisms in DNA isolated from 115 patients were analyzed: various number of 28-bp tandem repeats in 5′-UTR region of TS gene, single nucleotide polymorphism (SNP) within the second tandem repeat of TS gene (G>C); 6-bp deletion in 3′-UTR region of the TS (1494del6); 677C>T SNP in MTHFR; 19007C>T SNP in ERCC1. Molecular examinations’ results were correlated with disease control rate, progression-free survival (PFS) and overall survival.

Results

Polymorphic tandem repeat sequence (2R, 3R) in the enhancer region of TS gene and G>C SNP within the second repeat of 3R allele seem to be important for the effectiveness of platinum and pemetrexed in first-line chemotherapy. The insignificant shortening of PFS in 3R/3R homozygotes as compared to 2R/2R and 2R/3R genotypes were observed, while it was significantly shorter in patients carrying synchronous 3R allele and G nucleotide. The combined analysis of TS VNTR and MTHFR 677C>T SNP revealed shortening of PFS in synchronous carriers of 3R allele in TS and two C alleles in MTHFR. The strongest factors increased the risk of progression were poor PS, weight loss, anemia and synchronous presence of 3R allele and G nucleotide in the second repeat of 3R allele in TS. Moreover, lack of application of second-line chemotherapy, weight loss and poor performance status and above-mentioned genotype of TS gene increased risk of early mortality.

Conclusion

The examined polymorphisms should be accounted as molecular predictor factors for pemetrexed- and platinum-based front-line chemotherapy in non-squamous NSCLC patients.     

Crystal structure of the proteasomal deubiquitylation module Rpn8-Rpn11

The ATP-dependent degradation of polyubiquitylated proteins by the 26S proteasome is essential for the maintenance of proteome stability and the regulation of a plethora of cellular processes. Degradation of substrates is preceded by the removal of polyubiquitin moieties through the isopeptidase activity of the subunit Rpn11. Here we describe three crystal structures of the heterodimer of the Mpr1–Pad1–N-terminal domains of Rpn8 and Rpn11, crystallized as a fusion protein in complex with a nanobody. This fusion protein exhibits modest deubiquitylation activity toward a model substrate. Full activation requires incorporation of Rpn11 into the 26S proteasome and is dependent on ATP hydrolysis, suggesting that substrate processing and polyubiquitin removal are coupled. Based on our structures, we propose that premature activation is prevented by the combined effects of low intrinsic ubiquitin affinity, an insertion segment acting as a physical barrier across the substrate access channel, and a conformationally unstable catalytic loop in Rpn11. The docking of the structure into the proteasome EM density revealed contacts of Rpn11 with ATPase subunits, which likely stabilize the active conformation and boost the affinity for the proximal ubiquitin moiety. The narrow space around the Rpn11 active site at the entrance to the ATPase ring pore is likely to prevent erroneous deubiquitylation of folded proteins.In eukaryotes, the ubiquitin (Ub) proteasome system (UPS) is responsible for the regulated degradation of proteins (1–5). The UPS plays a key role in the maintenance of protein homeostasis by removing misfolded or damaged proteins, which could impair cellular functions, and by removing proteins whose functions are no longer needed. Consequently, the UPS is critically involved in numerous cellular processes, including cell cycle progression, apoptosis, and DNA damage repair, and malfunctions of the system often result in disease.The 26S proteasome executes the degradation of substrates that are marked for destruction by the covalent attachment of polyubiquitin chains. It is a molecular machine of 2.5 MDa comprising two subcomplexes, the 20S core particle (CP) and one or two 19S regulatory particles (RPs), which associate with the ends of the cylinder-shaped CP (6–8). The recognition and recruitment of polyubiquitylated substrates, their deubiquitylation, ATP-dependent unfolding, and translocation into the core particle take place in the RP. The structurally and mechanistically well-characterized CP houses the proteolytic activities and sequesters them from the environment, thereby avoiding collateral damage (9).The RPs attach to the outer α-rings of the CP, which control access to the proteolytic chamber formed by the inner β-subunit rings (10). Recently, the molecular architecture of the 26S holocomplex was established using cryo-EM–based approaches (11, 12), and a pseudoatomic model of the holocomplex was put forward (13). The RP is formed by two subcomplexes, known as the base and the lid, which assemble independently (12, 14). The base contains the hetero-hexameric AAA-ATPase ring (Rpt1–Rpt6), which drives the conformational changes required for substrate processing, including unfolding and translocation into the CP (15, 16). The base also contains the largest RP non-ATPase subunits, Rpn1 and Rpn2, and the Ub receptor Rpn13. The second resident Ub receptor, Rpn10, is not part of either the base or the lid; it binds only to the assembled 26S proteasome and is positioned close to the ATPase module.The lid scaffold is composed of the Rpn3, Rpn5, Rpn6, Rpn7, Rpn8, Rpn9, Rpn11, and Rpn12 subunits (14). These subunits can be grouped according to their domain structures. Rpn3, Rpn5, Rpn6, Rpn7, Rpn9, and Rpn12 each comprise an N-terminal helix repeat segment, a proteasome-COP9/signalosome-eIF3 (PCI) module, and a long helix at the C terminus (8). The Rpn8 and Rpn11 subunits each consist of an Mpr1–Pad1–N-terminal (MPN) domain, followed by long C-terminal helices (Fig. 1A). The PCI subunits form a horseshoe-shaped structure and the MPN domains form a heterodimer, which are connected by a large helical bundle, to which all subunits contribute (13, 17, 18). Each of these eight subunits has paralogs in the COP9/signalosome (CSN) and the elongation initiation factor 3 (eIF3), which likely adopt a similar architecture (18–21).Open in a separate windowFig. 1.Biochemical activity of the Rpn8-Rpn11 fusion protein. (A) Domain structures of Rpn8, Rpn11 and the fusion protein. (B) Ub₄ cleavage activity of 26S proteasome, WT Rpn8-Rpn11 and Rpn8-Rpn11 (E48Q). Cleavage of labeled peptide from Ub₄ was detected by the change in fluorescence polarization after 1hr incubation at 37 °C at the indicated concentrations. Values are normalized to maximum cleavage activity of 26S proteasome. The used 26S proteasome preparation contained only trace amounts of the DUB Ubp6.The lid strengthens the interaction between the CP and RP (17) and deubiquitylates substrates before their processing by the AAA-ATPase module and the CP. Cleavage of polyubiquitin chains from the substrate enables recycling of Ub into the cellular pool, and the removal of the unfolding-resistant Ub moieties promotes translocation of substrates. The MPN domain of Rpn11 contains the catalytic site for deubiquitylation (22, 23). Rpn11 belongs to the JAB1/MPN/Mov34 metalloenzyme (JAMM) family of metalloproteases, which provide the isopeptidase activities in the proteasome, CSN, and exo-deubiquitylating enzymes (DUBs), such as associated molecule with the SH3 domain of STAM-like protein (AMSH-LP). The signature motif for this family is a conserved glutamate upstream of a zinc-coordinating catalytic loop, H(S/T)HX₇SXXD, first revealed in the structure of an archaeal homolog, AfJAMM (24). The substrate-binding mode of JAMM DUBs was clarified by the crystal structure of AMSH-LP in complex with Lys63-linked diubiquitin (25). The other proteasomal MPN subunit, Rpn8, is catalytically inactive; it does not contain the JAMM motif and appears to have mainly a supporting role for Rpn11. Isolated Rpn11 is catalytically inactive, as is the isolated lid (22). Rpn11 is activated upon integration into the 26S holocomplex and is dependent on ATP hydrolysis (23). The 26S proteasome was recently shown to undergo large-scale conformational changes from a substrate-accepting conformation to a substrate-engaged conformation that may be critical for Rpn11 function (15, 26), but the mechanistic basis for the regulation of Rpn11 remains unclear. Loss-of-function mutants of the JAMM motif cause stalling of substrates above the mouth of the ATPase module and lead to clogging of the 26S proteasome (23, 26).Inhibitors of human Rpn11 (hRpn11, also known as POH1) have been proposed as potential antitumor agents working upstream of the β5 proteolytic subunits in the UPS. The β5 subunits have been clinically validated by the approval of bortezomib and carilfzomib for the treatment of hematologic malignancies. siRNA and mutagenesis studies show that expression of the zinc catalytic domain of hRpn11 is essential for cell survival (27). Inhibition of hRpn11 in combination with EGFR inhibition has been suggested to be beneficial in the treatment of nonsmall cell lung cancer (28). Overexpression of hRpn11 in cancer cells has been linked to their tumor escape from cytotoxic agents (29). Thus, hRpn11 is an attractive target for pharmacologic intervention of the UPS.Here we present three crystal structures of the catalytically active Rpn8/Rpn11 MPN heterodimer from Saccharomyces cerevisiae, revealing the details of the Rpn11 active site and the mode of interaction with other subunits. Not all structures show proper active site geometry, hinting at possible mechanisms preventing activation outside of the proteasome complex. The access path for the C-terminal peptide of the substrate-bound Ub is blocked by a highly conserved insertion specific to Rpn11. Fitting of the Rpn8-Rpn11 crystal structure into the cryo-EM density of both the substrate-accepting and substrate-engaged proteasome revealed how the subcomplex is situated between base and PCI domain subunits, which involves long insertions unique to Rpn11 and Rpn8. Contacts to the coiled coils and the oligosaccharide-binding fold (OB) domain ring of the AAA subunits appear to control active site geometry and proper access of the isopeptide bond segment. In the substrate-engaged proteasome, the catalytic center becomes situated just above the maw of the ATPase ring.