Pulmonary bullet embolism – a safe treatment strategy of a potentially fatal injury: a case report

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Tropomodulin’s Actin-Binding Abilities Are Required to Modulate Dendrite Development

There are many unanswered questions about the roles of the actin pointed end capping and actin nucleation by tropomodulins (Tmod) in regulating neural morphology. Previous studies indicate that Tmod1 and Tmod2 regulate morphology of the dendritic arbor and spines. Tmod3, which is expressed in the brain, had only a minor influence on morphology. Although these studies established a defined role of Tmod in regulating dendritic and synaptic morphology, the mechanisms by which Tmods exert these effects are unknown. Here, we overexpressed a series of mutated forms of Tmod1 and Tmod2 with disrupted actin-binding sites in hippocampal neurons and found that Tmod1 and Tmod2 require both of their actin-binding sites to regulate dendritic morphology and dendritic spine shape. Proximity ligation assays (PLAs) indicate that these mutations impact the interaction of Tmod1 and Tmod2 with tropomyosins Tpm3.1 and Tpm3.2. This impact on Tmod/Tpm interaction may contribute to the morphological changes observed. Finally, we use molecular dynamics simulations (MDS) to characterize the structural changes, caused by mutations in the C-terminal helix of the leucine-rich repeat (LRR) domain of Tmod1 and Tmod2 alone and when bound onto actin monomers. Our results expand our understanding of how neurons utilize the different Tmod isoforms in development

Focal adhesions: Transmembrane junctions between the extracellular matrix and the cytoskeleton

Many cells grown in tissue culture adhere tightly to the underlying substrate through discrete regions of the plasma membrane, referred to as adhesion plaques, focal contacts, or focal adhesions. In these regions where the surface of the cell comes closest to the substrate, the plasma membrane is specialized at its cytoplasmic face for anchoring stress fibers, the large bundles of microfilaments that are prominent in many cultured cells. In this review we discuss the composition and organization of focal adhesions. Many of their characteristics indicate that they are structurally and functionally equivalent to the adhesions made by many cells to the extracellular matrix (ECM) in vivo. We also consider the regulatory proteins that have been identified in focal adhesions since these regions are interesting not only as models for studying the links between the extracellular matrix and the cytoskeleton, but also as sites of transmembrane communication between the extracellular environment and the cytoplasm. Many features of focal adhesions, some of which are not considered here, have been reviewed previously (Burridge 1986; Woods and Couchman 1988)

Pretransplant assessment of human liver grafts by plasma lecithin: cholesterol acyltransferase (LCAT) activity in multiple organ donors.

In spite of the improved outcome of orthotopic liver transplantation (OLTx), primary graft nonfunction remains one of the life-threatening problems following OLTx. The purpose of this study was to evaluate plasma lecithin: cholesterol acyltransferase (LCAT) activity in multiple organ donors as a predictor of liver allograft viability prior to OLTx. Thirty-nine donors were studied during a 5-month period between April and August 1988. Allograft hepatectomy was performed using a rapid technique or its minor modification with hilar dissections, and the allografts were stored cold (4 degrees C) in University of Wisconsin (UW) solution. Early post-transplant allograft function was classified as good, fair, or poor, according to the highest SGOT, SGPT, and prothrombin time within 5 days following OLTx. Procurement records were reviewed to identify donor data, which included conventional liver function tests, duration of hospital stay, history of cardiac arrest, and graft ischemic time. Blood samples from the donors were drawn immediately prior to aortic crossclamp, and from these plasma LCAT activity was determined. Plasma LCAT activity of all donors was significantly lower than that of healthy controls (12.4 +/- 8.0 vs 39.2 +/- 13.3 micrograms/ml per hour, P less than 0.01). LCAT activity (16.4 +/- 8.3 micrograms/ml per hour) in donors of grafts with good function was significantly higher than that in those with fair (8.6 +/- 4.5 micrograms/ml per hour, P less than 0.01) or poor (7.3 +/- 2.4 micrograms/ml per hour, P less than 0.01) function.(ABSTRACT TRUNCATED AT 250 WORDS

Tropomyosin Tpm3.1 is required to maintain the structure and function of the axon initial segment

The axon initial segment (AIS) is the site of action potential initiation and serves as a cargo transport filter and diffusion barrier that helps maintain neuronal polarity. The AIS actin cytoskeleton comprises actin patches and periodic sub-membranous actin rings. We demonstrate that tropomyosin isoform Tpm3.1 co-localizes with actin patches and that the inhibition of Tpm3.1 led to a reduction in the density of actin patches. Furthermore, Tpm3.1 showed a periodic distribution similar to sub-membranous actin rings but Tpm3.1 was only partially congruent with sub-membranous actin rings. Nevertheless, the inhibition of Tpm3.1 affected the uniformity of the periodicity of actin rings. Furthermore, Tpm3.1 inhibition led to reduced accumulation of AIS structural and functional proteins, disruption in sorting somatodendritic and axonal proteins, and a reduction in firing frequency. These results show that Tpm3.1 is necessary for the structural and functional maintenance of the AIS.Peer reviewe

Pseudohyperphosphorylation of tau is sufficient to induce aberrant sprouting and activation of ERK1/2 in transgenic mice

Poster presentation: Hyperphosphorylation of tau is a characteristic of Alzheimer's disease (AD). Our group has established a model for tau hyperphosphorylation by mutating 10 residues from Ser/Thr to Glu to simulate the negative charge of phosphorylated residues ("pseudohyperphosphorylated (PHP)-tau"). In order to analyze temporal and spatial effects of hyperphosphorylation of tau in a systemic context, we have established transgenic mouse lines that express human wild-type (wt)- or PHP-tau under the control of the CamKIIalpha-promoter that leads to a forebrain specific moderate expression in neurons, i.e. the region where also tau-pathology in AD is abundant. For the evaluation of tau-induced changes in the transgenic mice, we quantified spine densities in the neocortex and hippocampus of transgenic mice. The spine densitiy was significantly increased in PHP-tau compared to wt-tau expressing mice. It is known that AD is associated with aberrant pre- and postsynaptic sprouting. Axonal sprouting is also observed in transgenic mice expressing mutated amyloid precursor protein (APP), which suggests that Abeta plays a significant role in this process. We deduce from our results, that (pseudo)-hyperphosphorylation of tau is sufficient to induce aberrant sprouting in the absence of Abeta. Analyses whether this sprouting is induced by pre- or postsynaptic changes and if functionally active synapses are formed are in progress. It will be interesting to determine if stabilization of these newly formed synapses slows or – in contrary – accelerates the progression of the disease. Sprouting as observed in our PHP-tau expressing mice is part of neuronal differentiation. One family of enzymes that is involved in cell differentiation are mitogen-acitvated protein kinases (MAPK). Western blot analysis was performed with brain lysates from transgenic mice to check whether PHP-tau induced sprouting is associated with MAPK activation. In fact, we also observed an increased activation of the MAPK ERK1/2 evident by phosphorylation of the residues Thr202 and Tyr204. ERK1/2 is also known to phosphorylate tau at sites characteristic for AD. Our results suggest the presence of a vicious circle by which (pseudo)-hyperphosphorylated tau activates ERK1/2 which in turn phosphorylates tau

Intensivist supervision of resident-placed central venous catheters decreases the incidence of catheter-related blood stream infections

Catheter-related blood stream infections (CRBSI) cause significant morbidity and mortality. A retrospective study of a performance improvement project in our teaching hospital's surgical intensive care unit (SICU) showed that intensivist supervision was important in reinforcing maximal sterile barriers (MSB) use during the placement of a central venous catheter (CVC) in the prevention of CRBSI. A historical control period, 1 January 2001–31 December 2003, was established for comparison. From 1 January 2003–31 December 2007, MSB use for central venous line placement was mandated for all operators. However, in 2003 there was no intensivist supervision of CVC placements in the SICU. The use of MSB alone did not cause a significant change in the CRBSI rate in the first year of the project, but close supervision by an intensivist in years 2004–2007, in conjunction with MSB use, demonstrated a significant drop in the CRBSI rate when compared to the years before intensivist supervision (2001–2003), p < .0001. A time series analysis comparing monthly rates of CRBSI (2001–2007) also revealed a significant downward trend, p = .028. Additionally, in the first year of the mandated MSB use (2003), 85 independently observed resident-placed CVCs demonstrated that breaks in sterile technique (34/85), as compared those placements that had no breaks in technique (51/85), had more CRBSI, 6/34 (17.6%) vs. 1/51 (1.9%), p < .01. Interventions to reduce CRBSI in our SICU needed emphasis on adequate supervision of trainees in CVC placement, in addition to use of MSB, to effect lower CRBSI rates

Implementation of the "FASTHUG" concept decreases the incidence of ventilator-associated pneumonia in a surgical intensive care unit

<p>Abstract</p> <p>Background</p> <p>Ventilator-associated pneumonia (VAP) is a leading cause of morbidity and mortality in critically ill patients. The Institute for Healthcare Improvement 100,000 Lives Campaign made VAP a target of prevention and performance improvement. Additionally, the Joint Commission on Accreditation of Health Organizations' 2007 Disease Specific National Patient Safety Goals included the reduction of healthcare-associated infections. We report implementation of a performance improvement project that dramatically reduced our VAP rate that had exceeded the 90^thpercentile nationally.</p> <p>Methods</p> <p>From 1 January 2004 to 31 December 2005 a performance improvement project was undertaken to decrease our critical care unit VAP rate. In year one (2004) procedural interventions were highlighted: aggressive oral care, early extubation, management of soiled or malfunctioning respiratory equipment, hand washing surveillance, and maximal sterile barrier precautions. In year two (2005) an evaluative concept called FASTHUG (daily evaluation of patients' feeding, analgesia, sedation, thromboembolic prophylaxis, elevation of the head of the bed, ulcer prophylaxis, and glucose control) was implemented. To determine the long-term effectiveness of such an intervention a historical control period (2003) and the procedural intervention period of 2004, i.e., the pre-FASTHUG period (months 1–24) were compared with an extended post-FASTHUG period (months 25–54).</p> <p>Results</p> <p>The 2003 surgical intensive care VAP rate of 19.3/1000 ventilator-days served as a historical control. Procedural interventions in 2004 were not effective in reducing VAP, p = 0.62. However, implementation of FASTHUG in 2005, directed by a critical care team, resulted in a rate of 7.3/1000 ventilator-days, p ≤ .01. The median pneumonia rate was lower after implementation of FASTHUG when compared to the historical control year (p = .028) and the first year after the procedural interventions (p = .041) using follow-up pairwise comparisons. The pre-FASTHUG period (2003–2004, months 1–24) when compared with an extended post-FASTHUG period (2005–2007, 25–54 months) also demonstrated a significant decrease in the VAP rate, p = .0004. This reduction in the post-FASTHUG period occurred despite a rising Severity of Illness index in critically ill patients, p = .001.</p> <p>Conclusion</p> <p>Implementation of the FASTHUG concept, in the daily evaluation of mechanically ventilated patients, significantly decreased our surgical intensive care unit VAP rate.</p

The structure of the scaffold nucleoporin Nup120 reveals a new and unexpected domain architecture

Nucleocytoplasmic transport is mediated by nuclear pore complexes (NPCs), enormous protein assemblies residing in circular openings in the nuclear envelope. The NPC is modular, with transient and stable components. The stable core is essentially built from two multiprotein complexes, the Y-shaped heptameric Nup84 complex and the Nic96 complex, arranged around an eightfold axis. We present the crystal structure of Nup120[subscript 1-757], one of the two short arms of the Y-shaped Nup84 complex. The protein adopts a compact oval shape built around a novel bipartite α-helical domain intimately integrated with a β-propeller domain. The domain arrangement is substantially different from the Nup85•Seh1 complex, which forms the other short arm of the Y. With the data presented here, we establish that all three branches of the Y-shaped Nup84 complex are tightly connected by helical interactions and that the β-propellers likely form interaction site(s) to neighboring complexes.National Institutes of Health (U.S.) (Grant GM77537)Pew Charitable Trusts (Scholar Award