Predicting Stroke Risk Based on Health Behaviours: Development of the Stroke Population Risk Tool (SPoRT)

Background

Health behaviours, important factors in cardiovascular disease, are increasingly a focus of prevention. We appraised whether stroke risk can be accurately assessed using self-reported information focused on health behaviours.

Methods

Behavioural, sociodemographic and other risk factors were assessed in a population-based survey of 82 259 Ontarians who were followed for a median of 8.6 years (688 000 person-years follow-up) starting in 2001. Predictive algorithms for 5-year incident stroke resulting in hospitalization were created and then validated in a similar 2007 survey of 28 605 respondents (median 4.2 years follow-up).

Results

We observed 3 236 incident stroke events (1 551 resulting in hospitalization; 1 685 in the community setting without hospital admission). The final algorithms were discriminating (C-stat: 0.85, men; 0.87, women) and well-calibrated (in 65 of 67 subgroups for men; 61 of 65 for women). An index was developed to summarize cumulative relative risk of incident stroke from health behaviours and stress. For men, each point on the index corresponded to a 12% relative risk increase (180% risk difference, lowest (0) to highest (9) scores). For women, each point corresponded to a 14% relative risk increase (340% difference, lowest (0) to highest (11) scores). Algorithms for secondary stroke outcomes (stroke resulting in death; classified as ischemic; excluding transient ischemic attack; and in the community setting) had similar health behaviour risk hazards.

Conclusion

Incident stroke can be accurately predicted using self-reported information focused on health behaviours. Risk assessment can be performed with population health surveys to support population health planning or outside of clinical settings to support patient-focused prevention.     

Measurement of Pulmonary Flow Reserve and Pulmonary Index of Microcirculatory Resistance for Detection of Pulmonary Microvascular Obstruction

Background

The pulmonary microcirculation is the chief regulatory site for resistance in the pulmonary circuit. Despite pulmonary microvascular dysfunction being implicated in the pathogenesis of several pulmonary vascular conditions, there are currently no techniques for the specific assessment of pulmonary microvascular integrity in humans. Peak hyperemic flow assessment using thermodilution-derived mean transit-time (T_mn) facilitate accurate coronary microcirculatory evaluation, but remain unvalidated in the lung circulation. Using a high primate model, we aimed to explore the use of T_mn as a surrogate of pulmonary blood flow for the purpose of measuring the novel indices Pulmonary Flow Reserve [PFR = (maximum hyperemic)/(basal flow)] and Pulmonary Index of Microcirculatory Resistance [PIMR = (maximum hyperemic distal pulmonary artery pressure)×(maximum hyperemic T_mn)]. Ultimately, we aimed to investigate the effect of progressive pulmonary microvascular obstruction on PFR and PIMR.

Methods and Results

Temperature- and pressure-sensor guidewires (TPSG) were placed in segmental pulmonary arteries (SPA) of 13 baboons and intravascular temperature measured. T_mn and hemodynamics were recorded at rest and following intra-SPA administration of the vasodilator agents adenosine (10–400 µg/kg/min) and papaverine (3–24 mg). Temperature did not vary with intra-SPA sensor position (0.010±0.009 v 0.010±0.009°C; distal v proximal; p = 0.1), supporting T_mn use in lung for the purpose of hemodynamic indices derivation. Adenosine (to 200 µg/kg/min) & papaverine (to 24 mg) induced dose-dependent flow augmentations (40±7% & 35±13% T_mn reductions v baseline, respectively; p<0.0001). PFR and PIMR were then calculated before and after progressive administration of ceramic microspheres into the SPA. Cumulative microsphere doses progressively reduced PFR (1.41±0.06, 1.26±0.19, 1.17±0.07 & 1.01±0.03; for 0, 10⁴, 10⁵ & 10⁶ microspheres; p = 0.009) and increased PIMR (5.7±0.6, 6.3±1.0, 6.8±0.6 & 7.6±0.6 mmHg.sec; p = 0.0048).

Conclusions

Thermodilution-derived mean transit time can be accurately and reproducibly measured in the pulmonary circulation using TPSG. Mean transit time-derived PFR and PIMR can be assessed using a TPSG and adenosine or papaverine as hyperemic agents. These novel indices detect progressive pulmonary microvascular obstruction and thus have with a potential role for pulmonary microcirculatory assessment in humans.     

Novel amino-piperidines as potent antibacterials targeting bacterial type IIA topoisomerases

We have identified a series of amino-piperidine antibacterials with a good broad spectrum potency. We report the investigation of various subunits in this series and advanced studies on compound 8. Compound 8 possesses good pharmacokinetics, broad spectrum antibacterial activity and demonstrates oral efficacy in a rat lung infection model.     

The SNPlex genotyping system: a flexible and scalable platform for SNP genotyping.

We developed the SNPlex Genotyping System to address the need for accurate genotyping data, high sample throughput, study design flexibility, and cost efficiency. The system uses oligonucleotide ligation/polymerase chain reaction and capillary electrophoresis to analyze bi-allelic single nucleotide polymorphism genotypes. It is well suited for single nucleotide polymorphism genotyping efforts in which throughput and cost efficiency are essential. The SNPlex Genotyping System offers a high degree of flexibility and scalability, allowing the selection of custom-defined sets of SNPs for medium- to high-throughput genotyping projects. It is therefore suitable for a broad range of study designs. In this article we describe the principle and applications of the SNPlex Genotyping System, as well as a set of single nucleotide polymorphism selection tools and validated assay resources that accelerate the assay design process. We developed the control pool, an oligonucleotide ligation probe set for training and quality-control purposes, which interrogates 48 SNPs simultaneously. We present performance data from this control pool obtained by testing genomic DNA samples from 44 individuals. in addition, we present data from a study that analyzed 521 SNPs in 92 individuals. Combined, both studies show the SNPlex Genotyping system to have a 99.32% overall call rate, 99.95% precision, and 99.84% concordance with genotypes analyzed by TaqMan probe-based assays. The SNPlex Genotyping System is an efficient and reliable tool for a broad range of genotyping applications, supported by applications for study design, data analysis, and data management.     

Interleukin-10 regulates arterial pressure in early primate pregnancy

OBJECTIVES: In pregnancy, the placental contribution of cytokines to maternal immunosuppression has been established, however their role in normal maternal blood pressure regulation has not been identified. We investigate the contribution of interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-alpha) to the vasodilation of early pregnancy in non-human primates. We also sequenced the IL-10 baboon gene and compared it with humans. METHODS: The effect of four different treatments, administered sequentially (semi-random-design) on resting 18h, night time, or hourly mean arterial pressure (MAP) and heart rate (HR) were measured using telemetry. An anti-human IL-10 monoclonal antibody (MAb, 1mg, n=7), anti-TNF-alpha antibody (n=3), a combination of anti-IL-10 and anti-TNF-alpha antibodies (n=5) or saline (n=3) control were administered intravenously to baboons in early pregnancy. Plasma and placental IL-10 concentration was measured before and after injection in all animals. RESULTS: Anti-human IL-10 MAb caused a significant increase in MAP of 2.6+/-0.5mmHg over the 18-h period (p<0.05). Administration of TNF-alpha alone or in combination with IL-10 did not alter MAP. There was 97% sequence homology of IL-10 cDNA between humans and baboons. CONCLUSIONS: IL-10 was shown to regulate the vasodilation of early pregnancy in Papio hamadryas. This partial role of IL-10 in the early BP response of primate pregnancy may be relevant to pathophysiological states of human pregnancy such as preeclampsia.     

Not all J domains are created equal: implications for the specificity of Hsp40-Hsp70 interactions

Heat shock protein 40s (Hsp40s) and heat shock protein 70s (Hsp70s) form chaperone partnerships that are key components of cellular chaperone networks involved in facilitating the correct folding of a broad range of client proteins. While the Hsp40 family of proteins is highly diverse with multiple forms occurring in any particular cell or compartment, all its members are characterized by a J domain that directs their interaction with a partner Hsp70. Specific Hsp40-Hsp70 chaperone partnerships have been identified that are dedicated to the correct folding of distinct subsets of client proteins. The elucidation of the mechanism by which these specific Hsp40-Hsp70 partnerships are formed will greatly enhance our understanding of the way in which chaperone pathways are integrated into finely regulated protein folding networks. From in silico analyses, domain swapping and rational protein engineering experiments, evidence has accumulated that indicates that J domains contain key specificity determinants. This review will critically discuss the current understanding of the structural features of J domains that determine the specificity of interaction between Hsp40 proteins and their partner Hsp70s. We also propose a model in which the J domain is able to integrate specificity and chaperone activity.     

A protein kinase C/Ras/ERK signaling pathway activates myeloid fibronectin receptors by altering beta1 integrin sialylation

Here we report that myeloid cells differentiating along the monocyte/macrophage lineage down-regulate the ST6Gal-I sialyltransferase via a protein kinase C/Ras/ERK signaling cascade. In consequence, the beta1 integrin subunit becomes hyposialylated, which stimulates the ligand binding activity of alpha5beta1 fibronectin receptors. Pharmacologic inhibitors of protein kinase C, Ras, and MEK, but not phosphoinositide 3-kinase, block ST6Gal-I down-regulation, integrin hyposialylation, and fibronectin binding. In contrast, constitutively active MEK stimulates these same events, indicating that ERK is both a necessary and sufficient activator of hyposialylation-dependent integrin activation. Consistent with the enhanced activity of hyposialylated cell surface integrins, purified alpha5beta1 receptors bind fibronectin more strongly upon enzymatic desialylation, an effect completely reversed by resialylation of these integrins with recombinant ST6Gal-I. Finally, we have mapped the N-glycosylation sites on the beta1 integrin to better understand the potential effects of differential sialylation on integrin structure/function. Notably, there are three N-glycosylated sites within the beta1 I-like domain, a region that plays a crucial role in ligand binding. Our collective results suggest that variant sialylation, induced by a specific signaling cascade, mediates the sustained increase in cell adhesiveness associated with monocytic differentiation.     

Haemodynamics using transthoracic echocardiography in healthy pregnant and non-pregnant baboons (Papio hamadryas)

Background To determine systolic and diastolic function using transthoracic echocardiography in the baboon (Papio hamadryas). Methods Transthoracic echocardiography was performed in eight non‐pregnant female and six pregnant baboons according to American Society of Echocardiography recommendations. Results Haemodynamic measurements were obtained from fourteen baboons. Compared to non‐pregnant baboons, pregnant baboons demonstrated: (mean ± SD, pregnant vs. healthy) increased cardiac output (1615 ± 121 ml/minutes vs. 1317 ± 134 ml/minutes P = 0.001) due to an increased heart rate [120 ± 11 beats per minute (BPM) vs. 105 ± 6 BPM P = 0.018]. The inter‐observer and intra‐observer variability (mean difference ± SD) for the left ventricular outflow tract diameter was 0.05 ± 0.07 cm and 0.01 ± 0.03 cm respectively. There was minimal impact to the animal’s daily activities. Conclusions Transthoracic echocardiography was applicable and reproducible for the assessment of haemodynamics in baboons thus enabling translation of animal results to human studies.