Paced QRS morphology predicts incident left ventricular systolic dysfunction and atrial fibrillation

Background

The prognostic significance of paced QRS complex morphology on surface ECG remains unclear. This study aimed to assess long-term outcomes associated with variations in the paced QRS complex.

MALT1-Ubiquitination Triggers Non-Genomic NF-κB/IKK Signaling upon Platelet Activation

We have recently shown that IKK complex plays an important non-genomic role in platelet function, i.e., regulates SNARE machinery-dependent membrane fusion. In this connection, it is well known that MALT1, whose activity is modulated by proteasome, plays an important role in the regulation of IKK complex. Therefore, the present studies investigated the mechanism by which IKK signaling is regulated in the context of the platelet proteasome. It was found that platelets express a functional proteasome, and form CARMA/MALT1/Bcl10 (CBM) complex when activated. Using a pharmacological inhibitor, the proteasome was found to regulate platelet function (aggregation, integrin activation, secretion, phosphatidylserine exposure and changes in intracellular calcium). It was also found to regulate thrombogenesis and physiologic hemostasis. We also observed, upon platelet activation, that MALT1 is ubiquitinated, and this coincides with the activation of the IKK/NF-κB-signaling pathway. Finally, we observed that the proteasome inhibitor blocks CBM complex formation and the interaction of IKKγ and MALT1; abrogates SNARE formation, and the association of MALT1 with TAK1 and TAB2, which are upstream of the CBM complex. Thus, our data demonstrate that MALT1 ubiquitination is critical for the engagement of CBM and IKK complexes, thereby directing platelet signals to the NF-κB pathway.     

Differential mapping of the amino acids mediating agonist and antagonist coordination with the human thromboxane A2 receptor protein

Despite the well documented involvement of thromboxane A(2) receptor (TPR) signaling in the pathogenesis of thrombotic diseases, there are currently no rationally designed antagonists available for clinical use. To a large extent, this derives from a lack of knowledge regarding the topography of the TPR ligand binding pocket. On this basis, the purpose of the current study was to identify the specific amino acid residues in the TPR protein that regulate ligand coordination and binding. The sites selected for mutation reside within or in close proximity to a region we previously defined as a TPR ligand binding region (i.e. the C terminus of the second extracellular loop and the leading edge of the fifth transmembrane domain). Mutation of these residues caused varying effects on the TPR-ligand coordination process. Specifically, the D193A, D193Q, and D193R mutants lost SQ29,548 (antagonist) binding and exhibited a dramatically reduced calcium response, which could not be restored by elevated U46619 (agonist) doses. The F184Y mutant lost SQ29,548 binding and exhibited a reduced calcium response (which could be restored by elevated U46619); and the T186A and S191T mutants lost SQ29,548 binding and retained a normal U46619-induced calcium response. Furthermore, these last three mutants also revealed a divergence in the binding of two structurally different antagonists, SQ29,548 and BM13.505. Two separate mutants that exhibited SQ29,548 binding yielded either a normal (F196Y) or reduced (S201T) U46619 response. Finally, mutation of other residues directly adjacent to those described above (e.g. E190A and F200A) produced no detectable effects on either SQ29,548 binding or the U46619-induced response. In summary, these results identify key amino acids (in particular Asp(193)) involved in TPR ligand coordination. These findings also demonstrate that TPR-specific ligands interact with different residues in the ligand-binding pocket.     

The P2Y12 Antagonists, 2-Methylthioadenosine 5��-Monophosphate Triethylammonium Salt and Cangrelor (ARC69931MX), Can Inhibit Human Platelet Aggregation through a Gi-independent Increase in cAMP Levels

ADP plays an integral role in the process of hemostasis by signaling through two platelet G-protein-coupled receptors, P2Y₁ and P2Y₁₂. The recent use of antagonists against these two receptors has contributed a substantial body of data characterizing the ADP signaling pathways in human platelets. Specifically, the results have indicated that although P2Y₁ receptors are involved in the initiation of platelet aggregation, P2Y₁₂ receptor activation appears to account for the bulk of the ADP-mediated effects. Based on this consideration, emphasis has been placed on the development of a new class of P2Y₁₂ antagonists (separate from clopidogrel and ticlopidine) as an approach to the treatment of thromboembolic disorders. The present work examined the molecular mechanisms by which two of these widely used adenosine-based P2Y₁₂ antagonists (2-methylthioadenosine 5′-monophosphate triethylammonium salt (2MeSAMP) and ARC69931MX), inhibit human platelet activation. It was found that both of these compounds raise platelet cAMP to levels that substantially inhibit platelet aggregation. Furthermore, the results demonstrated that this elevation of cAMP did not require G_i signaling or functional P2Y₁₂ receptors but was mediated through activation of a separate G protein-coupled pathway, presumably involving G_s. However, additional experiments revealed that neither 2MeSAMP nor ARC69931MX (cangrelor) increased cAMP through activation of A2a, IP, DP, or EP₂ receptors, which are known to couple to G_s. Collectively, these findings indicate that 2MeSAMP and ARC69931MX interact with an unidentified platelet G protein-coupled receptor that stimulates cAMP-mediated inhibition of platelet function. This inhibition is in addition to that derived from antagonism of P2Y₁₂ receptors.Upon damage to the endothelial layer of the blood vessel wall, the underlying subendothelium is exposed to platelets in the blood, initiating a cascade of signaling events resulting in the transformation of “resting” platelets into “activated” platelets (1). One significant characteristic associated with these signaling events is the secretion of ADP from the platelet-dense granules (2). This released ADP acts to further amplify the platelet activation response by interacting with its G-protein-coupled receptors on the platelet surface, namely P2Y₁ (coupled to G_q) and P2Y₁₂ (coupled to G_i) (3–5). The consequence of platelet activation through ADP is a conformational change in the platelet membrane glycoprotein αIIbβ3 (6, 7), which then binds to fibrinogen present in the plasma. The binding of fibrinogen with αIIbβ3 on the surface of adjacent platelets results in fibrinogen-platelet cross-linking and the formation of a hemostatic plug at the site of vascular injury (8).Consequently, ADP is thought to play an integral role in the normal process of hemostasis. Of the two ADP-receptor signaling pathways in platelets, evidence has indicated that ADP-mediated P2Y₁₂ signaling appears to play a more prominent role in platelet activation than ADP-mediated P2Y₁ signaling (9, 10). For the most part, support for this notion derives from the use of the adenosine-based P2Y₁₂ antagonists (i.e. 2MeSAMP⁴ and ARC69931MX), which have a much broader inhibitory profile than P2Y₁ antagonists (e.g. A3P5P (adenosine-3′-phosphate-5′-phosphate) or MRS2179) (9). Thus, 2MeSAMP and ARC69931MX inhibit platelet aggregation in response to multiple agonists, such as thromboxane A₂, collagen, thrombin, etc. (11–13), whereas P2Y₁ antagonists do not. On the other hand, this general requirement for P2Y₁₂ signaling seems to be inconsistent with earlier reports indicating that activation of certain platelet receptors (e.g. thromboxane A₂ receptor) can cause aggregation through ADP-independent mechanisms (14, 15). Based on this apparent inconsistency in the contribution of P2Y₁₂ signaling to the overall platelet activation response, the present study investigated the possibility that the broad spectrum of inhibitory activity of this new generation of P2Y₁₂ antagonists (i.e. MeSAMP and ARC69931MX) may derive from an elevation in platelet cAMP levels.Our data demonstrated that both 2MeSAMP and ARC69931MX do in fact significantly raise human platelet cAMP. Furthermore, this pharmacological effect is independent of P2Y₁₂-G_i signaling and appears to proceed through activation of a separate G_s-coupled platelet receptor. Taken together, the results therefore indicate that these adenosine-based P2Y₁₂ antagonists can produce their inhibition of platelet function through a cAMP-mediated mechanism.     

RGS10 Negatively Regulates Platelet Activation and Thrombogenesis

Regulators of G protein signaling (RGS) proteins act as GTPase activating proteins to negatively regulate G protein-coupled receptor (GPCR) signaling. Although several RGS proteins including RGS2, RGS16, RGS10, and RGS18 are expressed in human and mouse platelets, the respective unique function(s) of each have not been fully delineated. RGS10 is a member of the D/R12 subfamily of RGS proteins and is expressed in microglia, macrophages, megakaryocytes, and platelets. We used a genetic approach to examine the role(s) of RGS10 in platelet activation in vitro and hemostasis and thrombosis in vivo. GPCR-induced aggregation, secretion, and integrin activation was much more pronounced in platelets from Rgs10^-/- mice relative to wild type (WT). Accordingly, these mice had markedly reduced bleeding times and were more susceptible to vascular injury-associated thrombus formation than control mice. These findings suggest a unique, non-redundant role of RGS10 in modulating the hemostatic and thrombotic functions of platelets in mice. RGS10 thus represents a potential therapeutic target to control platelet activity and/or hypercoagulable states.     

Mechanisms of analgesic effect of mesenchymal stem cells in osteoarthritis pain

Osteoarthritis (OA) is the most common musculoskeletal disease, and it is a major cause of pain, disability and health burden. Pain is the most common and bothersome presentation of OA, but its treatment is still suboptimal, due to the short-term action of employed analgesics and their poor adverse effect profile. Due to their regenerative and anti-inflammatory properties, mesenchymal stem cells (MSCs) have been extensively investigated as a potential therapy for OA, and numerous preclinical and clinical studies found a significant improvement in joint pathology and function, pain scores and/or quality of life after administration of MSCs. Only a limited number of studies, however, addressed pain control as the primary end-point or investigated the potential mechanisms of analgesia induced by MSCs. In this paper, we review the evidence reported in literature that support the analgesic action of MSCs in OA, and we summarize the potential mechanisms of these antinociceptive effects.     

Platelet function and Isoprostane biology. Should Isoprostanes be the newest member of the Orphan-ligand family?

While there have been many reports investigating the biological activity and signaling mechanisms of isoprostanes, their role in biology, particularly in platelets, appears to still be underestimated. Moreover, whether these lipids have their own receptors is still debated, despite multiple reports that discrete receptors for isporpstanes do exist on platelets, vascular tissues, amongst others. This paper provides a review of the important literature of isoprostanes and provides reasoning that isoprostanes should be classified as orphan ligands until their receptor(s) is/are identified.     

Glutathione and adaptive immune responses against Mycobacterium tuberculosis infection in healthy and HIV infected individuals

Glutathione (GSH), a tripeptide antioxidant, is essential for cellular homeostasis and plays a vital role in diverse cellular functions. Individuals who are infected with Human immuno deficiency virus (HIV) are known to be susceptible to Mycobacterium tuberculosis (M. tb) infection. We report that by enhancing GSH levels, T-cells are able to inhibit the growth of M. tb inside macrophages. In addition, those GSH-replenished T cell cultures produced increased levels of Interleukin-2 (IL-2), Interleukin-12 (IL-12), and Interferon-gamma (IFN-γ), cytokines, which are known to be crucial for the control of intracellular pathogens. Our study reveals that T lymphocytes that are derived from HIV infected individuals are deficient in GSH, and that this deficiency correlates with decreased levels of Th1 cytokines and enhanced growth of M. tb inside human macrophages.     

Predictors and barriers to breastfeeding in north of Jordan: could we do better?

Background

Despite the ongoing recommendations for breastfeeding, we continue to see a decrease in exclusive breastfeeding among Jordanian women during infant follow up visits at the pediatric outpatient clinic. The purpose of our study is to determine the prevalence, predictors and barriers to exclusive breastfeeding in north of Jordan.

Methods

We conducted a cross-sectional survey involving mothers with infants six to twelve months old, at two hospitals in Irbid city in north of Jordan, between December 2016 and March 2017. Questions included demographics, feeding pattern, and reasons for non-exclusive breastfeeding.

Results

Five hundred women were included. Twenty four percent of women were employed and 87% initiated breastfeeding within three hours of birth. The proportion of women with any breastfeeding and exclusive breastfeeding at six months was 76 and 33%. After multivariate logistic regression analysis, predictors of exclusive breastfeeding at six months include the mother’s previous experience (Adjusted Odds Ratio [AOR] 7.9, 95% CI 4.69, 13.36) and multiparity (AOR 2.26, 95% CI 1.2, 4.28), while barriers include maternal employment (AOR 0.4, 95% CI 0.22,0.72), Cesarean delivery (AOR 0.55, 95% CI 0.35, 0.86) and infant’s hospitalization (AOR 0.44, 95% CI 0.23,0.82). Inadequate breastmilk supply and short maternity leave were the main reported reasons for non-exclusive breastfeeding.

Conclusions

In north of Jordan, the majority of women initiate breastfeeding, half practice exclusive breastfeeding after birth while one third continue for six months, particularly those with previous experience. Cesarean delivery and infant’s hospitalization, together with maternal employment are among the main barriers. Implementing educational programs and lactation consultant counselling together with work environment support, should be helpful to improve the breastfeeding practice among Jordanian women.

     

Fine needle aspiration cytology of lung lesions: a clinicopathological and cytopathological review of 150 cases with emphasis on the relation between the number of passes and the incidence of pneumothorax

Objective: The aim of this study was to review the lung fine needle aspirations (FNA) that were done in our hospital between January 1998 and April 2004. Interobserver agreement, sample adequacy and the relation between the number of passes and the occurrence of pneumothorax are presented. Study design: One hundred fifty cases of lung FNA from the department of pathology files were identified and the available specimens and patient charts were reviewed. The interobserver agreement was calculated. The relation between the number of passes and the subsequent development of pneumothorax was tested using Mann–Whitney U‐test. Results: The material of 132 patients (88%) out of 150 were retrieved and reviewed. There were 85 cases of non‐small cell lung cancer (NSCLC) (64.4%), nine cases of small cell lung cancer (6.8%), five cases of metastatic cancer (3.8%) and 33 cases were reported negative for cancer (25%). The NSCLC included 36 cases of adenocarcinoma (27.3%), 32 cases of squamous cell carcinoma (24.2%), and 17 cases of large cell undifferentiated carcinoma (12.9%). The interobserver agreement k was 0.93, (95% CI 0.87–0.98). The majority of cases (95.5%) were considered adequate for interpretation. The charts of 138 patients (92%) were reviewed for postprocedure radiologically confirmed pneumothorax. Sixteen patients (11.6%) developed pneumothorax only three of whom (2%) required a chest tube for treatment. The number of passes was identified in 118 patients (85.5%). The number of passes did not have a statistically significant association with the development of a pneumothorax (P = 0.747). Conclusion: Fine needle aspirations to diagnose lung lesions is a safe procedure with a low incidence of pneumothorax. Its findings are reproducible with high interobserver agreement. Immediate adequacy evaluation and triage by a pathologist guarantees adequate sample in most instances. The number of passes was not associated with an increased incidence of pneumothorax.