The in-vitro effect of fibrinogen, factor XIII and thrombin-activatable fibrinolysis inhibitor on clot formation and susceptibility to tissue plasminogen activator-induced fibrinolysis in hemodilution model

Patients suffering major traumatic or surgical bleeding are often exposed to hemodilution resulting in dilutional coagulopathy. The aim of this study was to evaluate in vitro the effects of fibrinogen, factor XIII and thrombin-activatable fibrinolysis inhibitor (TAFI) on clot formation and resistance to fibrinolysis in hemodilution conditions. Citrated whole blood from 36 healthy volunteers was diluted to 30 and 60% with lactated Ringer's solution. Blood samples were subsequently supplemented with fibrinogen, FXIII, TAFI or their combinations. Rotation thromboelastometry (ROTEM) in whole blood and thrombin generation in plasma were performed in the presence of CaCl? and tissue factor/EXTEM reagent, and fibrinolysis was induced by tissue plasminogen activator (tPA). Hemodilution was expressed by decrease of peak height in thrombin generation and α-angle and maximum clot firmness (MCF) in ROTEM. Fibrinogen, FXIII or TAFI did not correct the decrease in thrombin generation peak height. In ROTEM, spiking of diluted blood with fibrinogen stimulated clot propagation. In tPA-treated blood fibrinogen, FXIII and TAFI increased clot firmness and inhibited fibrinolysis. Stronger protection against fibrinolysis was achieved combining FXIII with TAFI. Hemodilution was associated with inhibition of thrombin generation; however, this effect was not sensitive to blood spiking with fibrinogen, FXIII and TAFI. In ROTEM, these hemostasis agents improved clot strength and decreased clot susceptibility to tPA in nondiluted and to more extent in diluted blood. The maximal protection against fibrinolysis was caused by TAFI. Combining FXIII with TAFI exerted synergistic inhibitory effect on fibrinolysis.     

EGFR Mutation Testing Practice in Advanced Non-Small Cell Lung Cancer

Purpose

Testing tumor samples for the presence of a mutation in the epithelial growth factor receptor (EGFR) gene is recommended for advanced non-squamous non-small cell lung cancer (NSCLC) patients. We aimed to collect data about common practice among Medical Oncologists treating lung cancer patients, regarding EGFR mutation testing in advanced NSCLC patients.

Methods

An internet-based survey was conducted among members of the Israeli Society for Clinical Oncology and Radiotherapy involved in the treatment of lung cancer patients.

Results

24 Oncologists participated in the survey. The participants encompass the Oncologists treating most of the lung cancer patients in Israel. 79 % of them use EGFR testing routinely for all advanced NSCLC patients. Opinions were split regarding the preferable biopsy site for EGFR testing material. 60 % of participants recommend waiting for EGFR test results prior to initiation of first-line therapy.

Conclusions

EGFR testing is requested in Israel routinely by most treating Oncologists for all advanced NSCLC patients, regardless of histology. In most cases, systemic treatment is deferred until the results of this test are received.     

Echocardiographic Changes in Patients Implanted With a Fully Magnetically Levitated Left Ventricular Assist Device (Heartmate 3)

Background

The Heartmate 3 (HM3) is a Conformiteé Européenne mark–approved left ventricular (LV) assist device (LVAD) with fully magnetically levitated rotor and features consisting of a wide range operational speeds, wide flow paths, and artificial pulse. We performed a hemodynamic-echocardiographic speed optimization evaluation in HM3-implanted patients to achieve optimal LV- and right ventricular (RV) shape.

From the Cover: Global view of the protein universe

To explore protein space from a global perspective, we consider 9,710 SCOP (Structural Classification of Proteins) domains with up to 70% sequence identity and present all similarities among them as networks: In the “domain network,” nodes represent domains, and edges connect domains that share “motifs,” i.e., significantly sized segments of similar sequence and structure. We explore the dependence of the network on the thresholds that define the evolutionary relatedness of the domains. At excessively strict thresholds the network falls apart completely; for very lax thresholds, there are network paths between virtually all domains. Interestingly, at intermediate thresholds the network constitutes two regions that can be described as “continuous” versus “discrete.” The continuous region comprises a large connected component, dominated by domains with alternating alpha and beta elements, and the discrete region includes the rest of the domains in isolated islands, each generally corresponding to a fold. We also construct the “motif network,” in which nodes represent recurring motifs, and edges connect motifs that appear in the same domain. This network also features a large and highly connected component of motifs that originate from domains with alternating alpha/beta elements (and some all-alpha domains), and smaller isolated islands. Indeed, the motif network suggests that nature reuses such motifs extensively. The networks suggest evolutionary paths between domains and give hints about protein evolution and the underlying biophysics. They provide natural means of organizing protein space, and could be useful for the development of strategies for protein search and design.How are proteins related to each other? Which physicochemical considerations affect protein evolution and how? A global view of the protein universe may shed light on these fundamental questions. It could also suggest new strategies for protein search and design (1–3). However, forming a global picture of the protein universe is difficult because we have to piece it together from the many local glimpses that our empirical data and computational tools provide. In other words, a global picture needs to portray the relationships among all proteins, yet we only have evidence of such relationships among several proteins, based on the similarity between their sequences, structures, and functions. The considerable size of the Protein Data Bank (4) also complicates this task.In particular, an intensely debated question is whether protein space is “discrete” or “continuous” (2, 3, 5–10). These terms are loosely defined. Discrete implies that the global picture consists of separate, island-like, structural entities. In the hierarchical protein domains Structural Classification of Proteins (SCOP) (11) these entities are termed “folds,” and in the CATH database (12) they are called “topologies.” Alternatively, “continuous” implies that the space between these entities is generally populated by cross-fold similarities (e.g., refs. 2, 5, 6, 9, 13–15). If such similarities are abundant, then one must account for them when organizing and searching proteins (5, 8, 16). In support of the abundance of such similarities is the remarkable success of structure prediction methods that piece together predictions of protein fragments or larger protein segments (e.g., ref. 17).There are different approaches to forming a global view of the protein universe (18). The most significant efforts are the ones embodied in the hierarchical classifications CATH and SCOP. However, a hierarchy implicitly assumes that there are isolated regions in protein space. An alternative approach is to study the protein universe via maps––where domains are represented by points in two or three dimensions, placed so that the distances between them depend on the dissimilarity between their corresponding domains (e.g., refs. 19–21). By coloring the points according to domain characteristics, one can visually identify global properties of the protein universe (19, 20). However, a map representation in low-dimensional Euclidean space implicitly suggests that similarity among domains is transitive (i.e., that similarity within the pairs AB and BC implies that AC is similar too); we know that this is often not the case (6). Finally, a third approach to study protein space is via similarity and cooccurrence networks. In similarity networks, nodes typically represent protein domains and edges connect similar domains. Several successful studies of protein space capitalize on such networks (22, 23). Cooccurrence networks of protein domains, in which nodes represent domains and edges connect cooccurring domains, were also studied to better understand protein evolution (24–26).Here, we study the global nature of the protein universe using domain and motif networks (Fig. 1). To construct these networks, we identify evolutionary relationships among a representative set of SCOP domains; we relate two domains if they share a significantly sized part (denoted motif) with similar structure and sequence. Our analysis reveals that protein space is both discrete and continuous: SCOP domains of the all-alpha, all-beta, and alpha + beta classes, in which alpha and beta elements do not mix, mostly populate the discrete parts, whereas alpha/beta domains, with alternating alpha and beta segments, mostly populate the continuous ones. We also find that recurring motifs are very abundant; the motifs from the all-alpha and alpha/beta domains are the more abundant, and the more gregarious ones.Open in a separate windowFig. 1.Constructing the domain and motif networks. (A) The aligned protein segments, marked in colors, are the motifs. (B) In the domain network, edges connect domains that share similar motifs (e.g., domain d1wjga_ and d1vlua_ that share the cyan motif). (C) In the motif network, edges connect cooccurring motifs (e.g., the orange and cyan motifs cooccur in the d1vlua_ domain).     

Correlation between radionuclides uptake and ultrastructural features of tight junctions in the capillary wall of meningiomas.

The uptake of Tc-99m pertechnetate and Co-57 bleomycin and the ultrastructure of small blood vessels were studied in 10 cases of meningioma. When thin sections of 120 contact areas between adjacent endothelial cells were examined, 92% of the intercellular contacts contained one to three punctate tight junctions. Freeze fracture preparations revealed fascia occludens with one to four sealing strands. These findings are consistent with the high permeability the meningiomas displayed for both of the radiopharmaceuticals.