An Sfi1-like centrin-interacting centriolar plaque protein affects nuclear microtubule homeostasis

Malaria-causing parasites achieve rapid proliferation in human blood through multiple rounds of asynchronous nuclear division followed by daughter cell formation. Nuclear divisions critically depend on the centriolar plaque, which organizes intranuclear spindle microtubules. The centriolar plaque consists of an extranuclear compartment, which is connected via a nuclear pore-like structure to a chromatin-free intranuclear compartment. Composition and function of this non-canonical centrosome remain largely elusive. Centrins, which reside in the extranuclear part, are among the very few centrosomal proteins conserved in Plasmodium falciparum. Here we identify a novel centrin-interacting centriolar plaque protein. Conditional knock down of this Sfi1-like protein (PfSlp) caused a growth delay in blood stages, which correlated with a reduced number of daughter cells. Surprisingly, intranuclear tubulin abundance was significantly increased, which raises the hypothesis that the centriolar plaque might be implicated in regulating tubulin levels. Disruption of tubulin homeostasis caused excess microtubules and aberrant mitotic spindles. Time-lapse microscopy revealed that this prevented or delayed mitotic spindle extension but did not significantly interfere with DNA replication. Our study thereby identifies a novel extranuclear centriolar plaque factor and establishes a functional link to the intranuclear compartment of this divergent eukaryotic centrosome.

P1924Population-wide disease trajectories in ischaemic heart disease

Background

Defining cardiovascular disease (CVD) phenotypes from large, longitudinal electronic health records (EHRs) through analysis of patient similarities and dissimilarities is a strategy with new possibilities to practice precision medicine. We carried out a pilot data screen to quantify and characterise selected CVD phenotypes from EHRs comprising medical histories of 6,986,632 individuals spanning 21 years.

Purpose

The overall aim is to define temporal CVD phenotypes by data-driven characterisation employing bioinformatics approaches. We have defined temporal CVD phenotypes, by data-driven characterisation identifying statistically significant temporal disease trajectories that allow for future integration of lab test results, drug prescriptions and genomic data.

Methods

Data was assessed by computing temporal disease trajectories made from selecting certain indicator diagnoses. Inclusion criterion was admittance to a Danish hospital during 1995–2016. All data points were indexed by a unique key for each individual in a registry based national infrastructure that is stable over a life time. Encryption was performed pre-analyses to acquire research prone patient IDs (PIDs). Diagnostic codes were annotated from EHRs according to the WHO ICD-10, tests according to the Nomenclature for Properties and Units (NPU), procedures according to the Danish Health Care Classification (SKS) and drug prescriptions according to the Anatomical Therapeutic Chemical Classification System (ATC).

Results

The largest subsets in the case population were cardiac arrhythmias (I44–49) and chronic ischaemic heart disease (I20-I25) counting 582,180 and 579,619 patients. respectively. Mapping of temporal disease trajectories leading to cardiac arrest (I46) one of four major CVD complications, demonstrated that the majority of cases matching chronic ischaemic heart disease (I25) who present with cardiac arrest (I46) do not have any intermediate diagnosis. This kind of trajectory illustrates the deep phenotypic spectrum of the most common type of I25 patients. Conversely, no direct disease trajectories were observed between patients diagnosed with cardiac arrest (I46) following myocardial infarction (I21) or heart failure (I50) (see figure). Overall, the population-based reference phenomes of the selected CVD diagnoses from the dataset used was verified using detailed EHR from a subset amounting to approximately 2.6 million patients.

Ischaemic heart disease trajectories

Conclusion

Mining of data from patients with chronic ischaemic heart disease by computing distinct disease trajectories leading to cardiac arrest provide a promising framework for establishing computational phenotypes. The multimorbidity trajectory approach allows us to define the longitudinal phenotype in the big data set. We argue that inclusion of additional data types including large-scale genomic analyses for sub-group stratification will elucidate disease mechanisms facilitating implementation of precision medicine.

Acknowledgement/Funding

NNF14CC0001 and 8114-00031B

Immunofluorescence staining protocol for STED nanoscopy of Plasmodium-infected red blood cells

Immunofluorescence staining is the key technique for visualizing organization of endogenous cellular structures in single cells. Labeling and imaging of blood stage Plasmodium falciparum has always been challenging since it is a small intracellular parasite. A widely-used standard for parasite immunofluorescence is fixation in suspension with addition of minute amounts of glutaraldehyde to the paraformaldehyde-based solution. While this maintains red blood cell integrity, it has been postulated that antigenicity of the parasite proteins was, if at all, only slightly reduced. Here we show the deleterious effect that even these small quantities of glutaraldehyde can have on immunofluorescence staining quality and present an alternative cell seeding protocol that allows fixation with only paraformaldehyde. The highly improved signal intensity and staining efficiency enabled us to carry out RescueSTED nanoscopy on microtubules and nuclear pores and describe their organization in greater detail throughout the blood stage cycle.

A two-phase response of endothelial cells to hydrostatic pressure

The vascular endothelium is exposed to three types of mechanical forces: blood flow-mediated shear stress, vessel-diameter dependent wall tension and hydrostatic pressure. Despite considerable variations of blood pressure in normal and pathological physiology, little is known about the acute molecular and cellular effects of hydrostatic pressure on endothelial cells. Here, we used a combination of quantitative fluorescence microscopy, atomic force microscopy and molecular perturbations to characterize the specific response of endothelial cells to pressure application. We identified a two-phase response of endothelial cells to acute (1 h) vs. chronic (24 h) pressure application (100 mmHg). While both regimes induce cortical stiffening, the acute response is linked to calcium-mediated myosin activation, whereas the chronic cell response is dominated by increased cortical actin density and a loss in endothelial barrier function. GsMTx-4 and amiloride inhibit the acute pressure response, which suggest the sodium channel ENaC as key player in endothelial pressure sensing. The described two-phase pressure response may participate in the differential effects of transient changes in blood pressure and hypertension.

Dyslexia and learning a foreign language: a personal experience

Individuals with dyslexia can expect to have difficulties learning a second language since second language learning builds on native language learning. The factors that have a negative impact on learning one's native language have a similar impact on learning a foreign language (e.g., difficulties with phonemic awareness, retrieving and processing linguistic information, working memory, metalinguistic explanations, stabilizing sound-symbol relationships). This participant observer report provides (1) a brief review of research on how dyslexia complicates learning a second language; (2) a description of how dyslexia has affected my educational experiences; (3) a description of personal experiences learning a foreign language between 1992-1998; and (4) recommendations for individuals with dyslexia who are faced with fulfilling a foreign language requirement and for their foreign language instructors.

Influence of spatial orientation of the C-6-OH group in ring C of morphine derivatives on opioid activity

The effect of epimerization on agonist and antagonist activities of morphine and dihydromorphine, and those of their N-allyl, -propyl and -cyclopropylmethyl derivatives, were studied in rat tail flick, hot plate and mice hot plate and in isolated guinea-pig ileum assays, respectively. Using the rat tail flick, hot plate and mice hot plate tests, isomorphine and dihydroisomorphine were observed to produce dose-dependent, naloxone-reversible agonist (antinociceptive) actions, in a similar dose range as their parent molecules (relative potencies: 0.6-1.9). Also, these compounds produced agonist activities in isolated tissue preparations in a naloxone-reversible manner. While the N-substituted derivatives of isomorphine and dihydroisomorphine failed to produce antinociceptive activities in the rat tail flick test, they proved to be strong agonists in the guinea-pig ileum experiments, although the Ke values of naloxone were 5-6 times higher against these compounds than against their N-CH3 counterparts. Both the agonist and antagonist activities of the N-cyclopropylmethyl derivatives were found to be most potent in the guinea-pig ileum. The epimerization of morphine and dihydromorphine and their N-substituted derivatives evoked only slight changes in opioid activities in vitro. In vivo, merely the allyl substitution on nitrogen influenced the antagonist activities of epimer pairs. In contrast, substantial changes in opioid profile were observed when N-methyl was replaced by allyl-, propyl- or cyclopropylmethyl. Changes performed this way evoked, on the one hand, an enhancement of the affinities of compounds to mu-receptors, with simultaneous loss of intrinsic efficacy at these receptors, and, on the other hand, promoted the appearance of an agonist profile on a distinct (kappa) opioid receptor.