Ischemic Stroke Thrombus Perviousness Is Associated with Distinguishable Proteomic Features and Susceptibility to ADAMTS13-Augmented Thrombolysis

BACKGROUND AND PURPOSE

Perviousness is the differential attenuation on CT of an intracranial arterial occlusive thrombus before and after IV contrast administration. While perviousness/permeability has been shown to be related to various clinical outcomes and reflects histopathologic composition, it remains unclear whether perviousness is also associated with differences in proteomic composition.

MATERIALS AND METHODS

Retrieved clots from 59 patients were evaluated with quantitative mass spectrometry. Proteomic differences between high-perviousness (≥11 HU) and low-perviousness (<11 HU) clots were investigated. Perviousness as a continuous variable was also correlated with protein abundance. Last, an ex vivo lysis assay was performed to investigate the differential susceptibility to tPA, deoxyribonuclease, and ADAMTS13 thrombolysis as a function of perviousness.

RESULTS

In total, 2790 distinct proteins were identified. Thrombus perviousness was associated with distinct proteomic features, including depletion of the macrophage marker CD14 (P = .039, z = 1.176) and hemoglobin subunit ζ (P = .046, z = 1.68) in pervious clots. Additionally, proteins involved in platelet cytoskeleton remodeling (tropomyosin α-3-chain) and granule secretion/aggregation (synaptotagmin-like protein 4/FC region receptor II-a) were associated with increasing perviousness (P < .006), among numerous other proteins. Monocyte/macrophage-associated proteins (apoptosis-associated specklike protein containing a CARD/SAMHD1) were also depleted in pervious emboli (P < .002). Ex vivo lysis indicated that pervious clots were more susceptible to ADAMTS13-augmented tPA thrombolysis compared with impervious clots (P < .05), though without differences in deoxyribonuclease digestion.

CONCLUSIONS

Thrombus perviousness is associated with complex proteomic features, including differential abundance of platelet-related proteins in highly permeable clots with monocyte/macrophage depletion. This association may help to explain why highly pervious thrombi were also found more susceptible to ADAMTS13-augmented thrombolysis.

CT hyperdense cerebral artery sign reflects distinct proteomic composition in acute ischemic stroke thrombus

BACKGROUND

Hyperdense cerebral artery sign (HCAS) is an imaging biomarker in acute ischemic stroke (AIS) that has been shown to be associated with various clinical outcomes and stroke etiology. While prior studies have correlated HCAS with histopathological composition of cerebral thrombus, it is unknown whether and to what extent HCAS is also associated with distinct clot protein composition.

METHODS

Thromboembolic material from 24 patients with AIS were retrieved via mechanical thrombectomy and evaluated with mass spectrometry in order to characterize their proteomic composition. Presence (+) or absence (-) of HCAS on preintervention non-contrast head CT was then determined and correlated with thrombus protein signature with abundance of individual proteins calculated as a function HCAS status.

RESULTS

24 clots with 1797 distinct proteins in total were identified. 14 patients were HCAS(+) and 10 were HCAS(-). HCAS(+) were most significantly differentially abundant in actin cytoskeletal protein (P=0.002, Z=2.82), bleomycin hydrolase (P=0.007, Z=2.44), arachidonate 12-lipoxygenase (P=0.004, Z=2.60), and lysophospholipase D (P=0.007, Z=2.44), among other proteins; HCAS(-) clots were differentially enriched in soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein (P=0.0009, Z=3.11), tyrosine-protein kinase Fyn (P=0.002, Z=2.84), and several complement proteins (P<0.05, Z>1.71 for all), among numerous other proteins. Additionally, HCAS(-) thrombi were enriched in biological processes involved with plasma lipoprotein and protein-lipid remodeling/assembling, and lipoprotein metabolic processes (P<0.001), as well as cellular components including mitochondria (P<0.001).

CONCLUSIONS

HCAS is reflective of distinct proteomic composition in AIS thrombus. These findings suggest that imaging can be used to identify mechanisms of clot formation or maintenance at the protein level, and might inform future research on thrombus biology and imaging characterization.

Abstract 124: The Immunometabolic Role Of Platelets In Uncomplicated Malaria Infection

The malaria causing Plasmodium parasite is a major public health threat. Plasmodium vivax (P vivax) is the cause of uncomplicated malaria (UCM). Platelets are the cellular mediators of thrombosis and are also the most numerous immune cells in the blood, and a first responder to infections. Thrombocytopenia is a frequent complication of malaria, and a decrease in platelet count is a negative predictor of disease outcome. Malaria infection elicits a strong interferon gamma (IFNγ) response. IFNγ is a potent inducer of indoleamine 2,3-dioxygenase (IDO1) the rate-limiting enzyme that catalyzes the first step in Tryptophan (Trp) metabolism in the kynurenine (Kyn) pathway, shunting Trp away from serotonin production. Trp metabolism may be altered in malaria infection as a means to regulate immunometabolic responses, but the mechanisms remain unknown. Our platelet RNA-sequencing data from P vivax infected humans and from P yoelii infected mice showed increased expression of genes related to Trp metabolism, including IDO1 . The role for platelets in metabolic pathway regulation is poorly explored in general, but particularly in infectious diseases. We introduce a novel idea that platelets participate in immunometabolism to infection. Using complementary experimental approaches such as liquid chromatography-mass spectrometry, ELISA, PCR, western blot, and flow cytometry, we test the hypothesis that platelets are a source of IDO1 in UCM malaria, and thrombocytopenia results in IDO1 depletion and immune dysregulation. We have discovered a role for platelets in Trp metabolic pathway regulation and that platelet regulated immune responses to malaria infection are in part dependent on the Trp metabolic pathways. During P yoelii infection there is a depletion of Trp, and increased Kyn metabolites, as well as decreased plasma serotonin. Platelet transfusions to infected mice can increase Kyn. Understanding the interplay between platelets and immunometabolic pathways may provide a better understanding of the impact of thrombocytopenia in diseases beyond malaria, and provide a means to improve malaria infection responses as well as improved platelet-directed therapeutics in many hematological, metabolic, and immune diseases .

Tumor Necrosis Factor Induces Obliterative Pulmonary Vascular Disease in a Novel Model of Connective Tissue Disease-Associated Pulmonary Arterial Hypertension

OBJECTIVE

Connective tissue disease (CTD)-associated pulmonary arterial hypertension (PAH) is the second most common etiology of PAH and carries a poor prognosis. Recently, it has been shown that female human tumor necrosis factor (TNF)-transgenic (Tg) mice die of cardiopulmonary disease by 6 months of age. This study was undertaken to characterize this pathophysiology and assess its potential as a novel model of CTD-PAH.

METHODS

Histologic analysis was performed on TNF-Tg and wild-type (WT) mice to characterize pulmonary vascular and right ventricular (RV) pathology (n = 40 [4-5 mice per group per time point]). Mice underwent right-sided heart catheterization (n = 29) and micro-computed tomographic angiography (n = 8) to assess vascular disease. Bone marrow chimeric mice (n = 12), and anti-TNF-treated mice versus placebo-treated mice (n = 12), were assessed. RNA sequencing was performed on mouse lung tissue (n = 6).

RESULTS

TNF-Tg mice displayed a pulmonary vasculopathy marked by collagen deposition (P < 0.001) and vascular occlusion (P < 0.001) with associated RV hypertrophy (P < 0.001) and severely increased RV systolic pressure (mean ± SD 75.1 ± 19.3 mm Hg versus 26.7 ± 1.7 mm Hg in WT animals; P < 0.0001). TNF-Tg mice had increased α-smooth muscle actin (α-SMA) staining, which corresponded to proliferation and loss of von Willebrand factor (vWF)-positive endothelial cells (P < 0.01). There was an increase in α-SMA-positive, vWF-positive cells (P < 0.01), implicating endothelial-mesenchymal transition. Bone marrow chimera experiments revealed that mesenchymal but not bone marrow-derived cells are necessary to drive this process. Treatment with anti-TNF therapy halted the progression of disease. This pathology closely mimics human CTD-PAH, in which patient lungs demonstrate increased TNF signaling and significant similarities in genomic pathway dysregulation.

CONCLUSION

The TNF-Tg mouse represents a novel model of CTD-PAH, recapitulates key disease features, and can serve as a valuable tool for discovery and assessment of therapeutics.

Abstract 140: Real-time Modulation of Platelet Phenotype and Vein Wall Biology in Patients with Chronic Venous Insufficiency

Background: The role of antiplatelet agents in the modulation of arterial disease is well described, but a paucity of data exists regarding their role in chronic venous insufficiency (CVI). We hypothesize that platelet responses to various antiplatelet agents are altered when comparing platelet function within refluxing and non-refluxing vein segments. Additionally, changes in platelet phenotype may alter vein wall biology.

Methods: Isolated platelets were obtained simultaneously from the patient antecubital vein (ACV) and a refluxing greater saphenous vein (GSV) during surgical phlebectomy and compared to platelets from healthy individuals. Non-refluxing GSV was harvested for coronary bypass. Platelet surface receptor activation was assessed through P2Y12 (clopidogrel), PAR1 (vorapaxar), and thromboxane (aspirin) pathways by flow cytometry for p-selectin. Immunoblotting assessed CD41 (platelet) and CD45 (WBC) within the wall of vein samples.

Results: Platelets from refluxing GSV showed a significant increase in reactivity via all platelet signaling pathways, especially P2Y12 and thromboxane when compared to platelets from the ACV in the same patient. Conversely, platelets collected from the ACV in CVI patients showed a significant decrease in reactivity to all agonists compared to ACV in healthy individuals without CVI. Most notably, GSV from a patient with CVI had a reduction in CD41 content, but a seven-fold increase in the CD45:CD41 ratio, compared to GSV from healthy people (Figure).

Conclusions: Platelet activation by these clinically relevant pathways is enhanced locally in the refluxing GSV, yet systemic, circulating platelets isolated from CVI patients are 2-3-fold less active than systemic platelets from healthy people. Our data suggest that reflux may locally alter the circulating platelet phenotype and in turn also have a role in remodeling the vein wall.

Abstract 57: Platelet Extracellular-signal-regulated Kinase 5 is a Redox Switch which Regulates Myocardial Infarct Expansion via Matrix Metalloproteinases

Background: Dysregulated platelet activation in an ischemic microvascular environment may play a role in myocardial infarction (MI). Platelet receptor signaling is well-characterized, but mechanisms of receptor-independent activation, such as by reactive oxygen species (ROS) generated in ischemic conditions, are less well understood. We discovered that ERK5, a nuclear protein which is ROS-activated in others cells, is abundantly present in platelets. We investigated whether ERK5 could regulate platelet activation and thrombosis in healthy and diseased states.

Methods: Human and mouse platelets were stimulated with agonists including ADP, U46619, TRAP, convulxin, or ROS (H 2 O 2 or 5% O 2 ). ERK5 activity was assessed by immunoblotting. Platelet activation was assessed via fluorescent-activated cell sorting (FACS) for P-selectin or activated GPIIb/IIIa. Intravascular thrombus (pulmonary embolus) or mesenteric thrombus (oxidative injury) formation was assessed by ex vivo fluorescent imaging and in vivo intravital microscopy, respectively. MI was performed in wild-type (WT) and in platelet specific ERK5 deficient (ERK5 -/- ) mice by LAD coronary artery ligation. Left ventricular (LV) function was determined by echocardiography. Matrix metalloproteinase (MMP) activity was determined by in-gel zymography.

Results: Human and platelet ERK5 was activated by ROS and via the thrombin and thromboxane receptors, but not via the purinergic or collagen receptors. Murine in vivo thrombosis was regulated by platelet ERK5 only if the injury involved oxidative stress. MI in mice promoted sustained platelet activation over one week in an ERK5-dependent manner. Following MI, platelet ERK5 -/- mice had less reactive platelets, less platelet MMP activity and thromboxane production, attenuated MMP activity in the LV, less remodeling with smaller infarcts, and enhanced myocardial systolic performance.

Conclusions: ERK5 is an ischemic sensor in platelets which regulates ongoing platelet activation after MI as well as remodeling via myocardial microvasculature. These observations may explain ischemic microvascular aberrations like the no-reflow phenomenon following percutaneous coronary intervention, suggesting a novel pharmacologic target.

Identification of activators of ERK5 transcriptional activity by high-throughput screening and the role of endothelial ERK5 in vasoprotective effects induced by statins and antimalarial agents

Because ERK5 inhibits endothelial inflammation and dysfunction, activating ERK5 might be a novel approach to protecting vascular endothelial cells (ECs) against various pathological conditions of the blood vessel. We have identified small molecules that protect ECs via ERK5 activation and determined their contribution to preventing cardiac allograft rejection. Using high-throughput screening, we identified certain statins and antimalarial agents including chloroquine, hydroxychloroquine, and quinacrine as strong ERK5 activators. Pitavastatin enhanced ERK5 transcriptional activity and Kruppel-like factor-2 expression in cultured human and bovine ECs, but these effects were abolished by the depletion of ERK5. Chloroquine and hydroxychloroquine upregulated ERK5 kinase activity and inhibited VCAM-1 expression in an ERK5-dependent but MAPK/ERK kinase 5- and Kruppel-like factor 2/4-independent manner. Leukocyte rolling and vascular reactivity were used to evaluate endothelial function in vivo, and we found that EC-specific ERK5 knockout (ERK5-EKO) mice exhibited increased leukocyte rolling and impaired vascular reactivity, which could not be corrected by pitavastatin. The role of endothelial ERK5 in acute cardiac allograft rejection was also examined by heterotopic grafting of the heart obtained from either wild-type or ERK5-EKO mice into allomismatched recipient mice. A robust increase in both inflammatory gene expression and CD45-positive cell infiltration into the graft was observed. These tissue rejection responses were inhibited by pitavastatin in wild-type but not ERK5-EKO hearts. Our study has identified statins and antimalarial drugs as strong ERK5 activators and shown that ERK5 activation is preventive of endothelial inflammation and dysfunction and acute allograft rejection.

Cathepsin G-dependent modulation of platelet thrombus formation in vivo by blood neutrophils

Neutrophils are consistently associated with arterial thrombotic morbidity in human clinical studies but the causal basis for this association is unclear. We tested the hypothesis that neutrophils modulate platelet activation and thrombus formation in vivo in a cathepsin G-dependent manner. Neutrophils enhanced aggregation of human platelets in vitro in dose-dependent fashion and this effect was diminished by pharmacologic inhibition of cathepsin G activity and knockdown of cathepsin G expression. Tail bleeding time in the mouse was prolonged by a cathepsin G inhibitor and in cathepsin G knockout mice, and formation of neutrophil-platelet conjugates in blood that was shed from transected tails was reduced in the absence of cathepsin G. Bleeding time was highly correlated with blood neutrophil count in wildtype but not cathepsin G deficient mice. In the presence of elevated blood neutrophil counts, the anti-thrombotic effect of cathepsin G inhibition was greater than that of aspirin and additive to it when administered in combination. Both pharmacologic inhibition of cathepsin G and its congenital absence prolonged the time for platelet thrombus to form in ferric chloride-injured mouse mesenteric arterioles. In a vaso-occlusive model of ischemic stroke, inhibition of cathepsin G and its congenital absence improved cerebral blood flow, reduced histologic brain injury, and improved neurobehavioral outcome. These experiments demonstrate that neutrophil cathepsin G is a physiologic modulator of platelet thrombus formation in vivo and has potential as a target for novel anti-thrombotic therapies.

Abstract 59: Platelets Have a Central Role in T Helper Cell Development and Responses

Platelets are the primary cellular mediator of thrombosis, but platelets also have important roles in immune responses. Immune roles for platelets have been primarily explored in the context of endothelial cell interactions and innate immune responses, but our work now demonstrates an important and novel role for platelets in T cell development. Using the mouse abdominal cardiac transplantation model we have discovered that platelets have a central role in CD4+ T helper cell development and differentiation. Platelet deficient thrombopoietin receptor (TPOR/c-MPL) knockout mice given cardiac transplants have an accelerated rejection response driven by Th17 type of CD4+ T cell activation and infiltration of transplant tissue. These mice also have a basal skewing to Th17 development in the absence of transplantation. Platelets are the primary source of platelet factor 4 (PF4/CXCL4) and PF4-/- mice exhibit a very similar phenotype of unrestrained Th17 T cell development and responses post transplantation as the TPOR-/- mice. Furthermore, PF4 directly limits in vitro Th17 cell differentiation, demonstrating that platelets via PF4 have a major prior unrecognized role in T helper cell differentiation.

Taken together, these data demonstrate a highly novel platelet function in T helper cell development. PF4 has a direct effect on maintaining T cell homeostasis and differentiation which is highly relevant to transplant immune responses and chronic rejection.

The burden of obesity on blood pressure is reduced in older persons: the SardiNIA study

INTRODUCTION

Being overweight or obese increases the risk of elevated blood pressure. However differences of their effects on blood pressure in different age groups are not clear.

OBJECTIVE

The aim of the present study was to evaluate differences of the effects of adiposity on the odds of having hypertension in different age groups.

DESIGN AND METHODS

Three thousand fifty-six subjects (1,532 women and 1,524 men) consist of the drug naïve subjects from the SardiNIA study. Logistic regression models with backward elimination were used to determine and compare the association between categories of obesity on hypertension within young (≤ 39), middle aged (40-59), and older (60+) subjects. Additional terms controlled for in the model were smoking and alcohol intake status.

RESULTS

The relationship of body mass index (BMI) on hypertension differed by age, as indicated by the significant interaction term of age with BMI (P <0.01). Older subjects had higher odds of having hypertension than younger subjects but these odds were lower for obese than for lean subjects (OR 10.45, 95% CIs 4.58-23.85 in obese versus OR 33.89, 95% CIs 17.94-64.02 in lean subjects). A similar trend was also observed in middle aged subjects.

CONCLUSIONS

This study shows that among men and women, older age was associated with a lesser effect of BMI on the odds of having hypertension.

A crucial role for p90RSK-mediated reduction of ERK5 transcriptional activity in endothelial dysfunction and atherosclerosis

BACKGROUND

Diabetes mellitus is a major risk factor for cardiovascular mortality by increasing endothelial cell (EC) dysfunction and subsequently accelerating atherosclerosis. Extracellular-signal regulated kinase 5 (ERK5) is activated by steady laminar flow and regulates EC function by increasing endothelial nitric oxide synthase expression and inhibiting EC inflammation. However, the role and regulatory mechanisms of ERK5 in EC dysfunction and atherosclerosis are poorly understood. Here, we report the critical role of the p90 ribosomal S6 kinase (p90RSK)/ERK5 complex in EC dysfunction in diabetes mellitus and atherosclerosis.

METHODS AND RESULTS

Inducible EC-specific ERK5 knockout (ERK5-EKO) mice showed increased leukocyte rolling and impaired vessel reactivity. To examine the role of endothelial ERK5 in atherosclerosis, we used inducible ERK5-EKO-LDLR(-/-) mice and observed increased plaque formation. When activated, p90RSK associated with ERK5, and this association inhibited ERK5 transcriptional activity and upregulated vascular cell adhesion molecule 1 expression. In addition, p90RSK directly phosphorylated ERK5 S496 and reduced endothelial nitric oxide synthase expression. p90RSK activity was increased in diabetic mouse vessels, and fluoromethyl ketone-methoxyethylamine, a specific p90RSK inhibitor, ameliorated EC-leukocyte recruitment and diminished vascular reactivity in diabetic mice. Interestingly, in ERK5-EKO mice, increased leukocyte rolling and impaired vessel reactivity were resistant to the beneficial effects of fluoromethyl ketone-methoxyethylamine, suggesting a critical role for endothelial ERK5 in mediating the salutary effects of fluoromethyl ketone-methoxyethylamine on endothelial dysfunction. Fluoromethyl ketone-methoxyethylamine also inhibited atherosclerosis formation in ApoE(-/-) mice.

CONCLUSIONS

Our study highlights the importance of the p90RSK/ERK5 module as a critical mediator of EC dysfunction in diabetes mellitus and atherosclerosis formation, thus revealing a potential new target for therapeutic intervention.

Phosphorylation of protein inhibitor of activated STAT1 (PIAS1) by MAPK-activated protein kinase-2 inhibits endothelial inflammation via increasing both PIAS1 transrepression and SUMO E3 ligase activity

OBJECTIVE

Protein inhibitor of activated signal transducer and activator of transcription-1 (PIAS1) is known to function as small ubiquitin-like modifier (SUMO) E3 ligase as well as transrepressor. The aim of the study is to elucidate the regulatory mechanisms for these 2 different functions, especially with respect to endothelial inflammation.

METHODS AND RESULTS

The mitogen-activated protein kinase (MAPK)-activated protein kinase-2 is a proinflammatory kinase and phosphorylates PIAS1 at the Ser522 residue. Activation of MAPK-activated protein kinase-2 enhances p53-SUMOylation, but a PIAS1 phosphorylation mutant, PIAS1-S522A, abolished this p53-SUMOylation, suggesting a critical role for PIAS1-S522 phosphorylation in its SUMO ligase activity. Because nuclear p53 can inhibit Kruppel-like factor 2 promoter activity, we investigated the roles for PIAS1 phosphorylation and p53-SUMOylation in the Kruppel-like factor 2 and endothelial NO synthase expression. Both MAPK-activated protein kinase-2 and PIAS1 overexpression increased Kruppel-like factor 2 promoter activity and endothelial NO synthase expression, which were inhibited by expressing a p53-SUMOylation defective mutant, p53-K386R, and PIAS1-S522A. PIAS1-S522A also abolished the anti-inflammatory effect of wild-type PIAS1 in vitro and also in vivo, which was examined by leukocyte rolling in microvessels of skin grafts transduced by adenovirus encoding PIAS1-WT or - S522A mutant.

CONCLUSIONS

Our study has identified a novel negative feedback regulatory pathway through which MAPK-activated protein kinase-2 limits endothelial inflammation via the PIAS1 S522 phosphorylation-mediated increase in PIAS1 transrepression and SUMO ligase activity.

p90RSK targets the ERK5-CHIP ubiquitin E3 ligase activity in diabetic hearts and promotes cardiac apoptosis and dysfunction

RATIONALE

Cardiomyocyte apoptosis is one of the key events in the development and progression of heart failure, and a crucial role for ICER (inducible cAMP early repressor) in this process has been previously reported. ERK5 is known to inhibit cardiac apoptosis after myocardial infarction (MI), especially in hyperglycemic states, via association with CHIP ubiquitin (Ub) ligase and subsequent upregulation of CHIP ligase activity, which induces ICER ubiquitination and subsequent protein degradation. The regulatory mechanism governing ERK5/CHIP interaction is unknown.

OBJECTIVE

We previously demonstrated increased p90RSK activation in the diabetic heart. As a logical extension of this work, we now investigate whether p90RSK activation inhibits ERK5-mediated CHIP activation, and subsequently increases ICER levels and apoptosis.

METHODS AND RESULTS

p90RSK activation inhibits ERK5/CHIP association and CHIP Ub ligase activity. p90RSK and CHIP share a common binding site in the ERK5 C-terminal domain (aa571-807). Overexpression of either p90RSK or an ERK5 fragment (aa571-807) inhibits ERK5/CHIP association, suggesting that p90RSK and CHIP competes for ERK5 binding and that p90RSK activation is critical for inhibiting ERK5/CHIP interaction. We also identified ERK5-S496 as being directly phosphorylated by p90RSK and demonstrated that an ERK5-S496A mutant significantly impairs Angiotensin II-mediated inhibition of CHIP activity and subsequent increase in ICER levels. In vivo, either cardiac-specific depletion of ERK5 or overexpression of p90RSK inhibits CHIP activity and accelerates cardiac apoptosis after MI-a phenomenon fully reversible by activating ERK5.

CONCLUSIONS

These data suggest a role for p90RSK in inhibiting CHIP activity and promoting cardiac apoptosis through binding to and phosphorylation of ERK5-S496.

Interspecies Uptake of Polymeric Microspheres

Particle uptake into intestinal tissue has seen increasing attention due to its implications in drug delivery. We attempted to observe a delivery system in vivo and examine uptake in different species. Microspheres were fabricated from polymers including polyanhydrides and delivered to an isolated loop of intestine in several species. The microspheres contained a dye either conjugated to a protein or incorporated freely and were used to qualitatively detect and locate the spheres in the villi of the length of the small intestine. Microspheres were dispersed, sized by a Coulter particle size analyzer, and characterized by confocal and cross-polarized light microscopy, FTIR and SEM. Coulter analysis revealed microspheres to be generally less than 5 microns in diameter. SEM typically showed homogeneous morphology among groups of microspheres. In vivo uptake experiments were performed in rodents, pigs, and ruminants using various microsphere formulations. Microspheres were delivered into the proximal end of the jejunum of anesthetized animals and allowed adequate transit time to be taken up. Animals were euthanized at various time points for explantation of tissue and sampling of blood. Excised samples were embedded inq polyvinyl alcohol, frozen, and cut into sections ranging between 7 and 14 μm in thickness. Our method of incorporating dyes allowed for simultaneous visualization by visible light microscopy and confocal laser scanning microscopy. Two-fluorochrome fluorescence of the microspheres and optical sectioning confirmed the presence of microspheres within intestinal tissue. The amount of uptake depended on the animal model, the duration of the experiment, and the composition of the microsphere. An assay for either the fluorescent dye, the protein attached to it, or the polymer encapsulating it may enable us to determine intracellular concentrations of mierospheres for the quantification of uptake.

The British Cardiac Society Working Group definition of myocardial infarction: implications for practice

OBJECTIVE

To assess the impact on observed mortality of the British Cardiac Society (BCS) definition of myocardial infarction (MI) in 11 UK hospitals.

DESIGN

Prospective observational registry.

SETTING

11 adjacent hospitals in the West Yorkshire region.

PATIENTS

2484 patients with the acute coronary syndrome (ACS) were identified during a six month period (28 April to 28 October 2003). Demographic, clinical, and treatment variables were collected on all patients. Deaths were monitored through the Office of National Statistics. Patients were categorised into three groups according to the BCS definition of MI: ACS with unstable angina (UA), ACS with myocyte necrosis, and ACS with clinical MI.

RESULTS

30 day mortality was 4.5%, 10.4%, and 12.9% (p < 0.001) in the ACS with UA, ACS with myocyte necrosis, and ACS with clinical MI groups, respectively. At six months the mortality for patients in the groups ACS with clinical MI and ACS with myocyte necrosis was similar (19.2% v 18.7%), being higher than for ACS with UA (8.6%). Same admission percutaneous coronary intervention was similar in groups with clinical MI and myocyte necrosis (11.1% v 10.7%, respectively) as was coronary artery bypass grafting (2.6% v 2.7%, respectively). However, these two groups differed significantly in the prescribing of secondary prevention (aspirin, 79% v 69%; statins, 80% v 68%; beta blockers, 66% v 53%; and angiotensin converting enzyme inhibitors, 65% v 53%; p < 0.001).

CONCLUSIONS

At 30 days the new BCS categories for MI predict three distinct outcomes. However, within a contemporary UK population this was no longer apparent at six months, as mortality for patients with ACS with myocyte necrosis had risen to the same level as those for patients with ACS with clinical MI. One possible explanation for this is the apparent under use of drugs known to improve prognosis after traditionally defined MI.

An evaluation of the relationship between specialist training in cardiology and implementation of evidence-based care of patients following acute myocardial infarction

AIMS

Large clinical trials have provided evidence of prognostically beneficial treatment strategies for patients with acute myocardial infarction. However, the implementation of this evidence into routine clinical practice is suboptimal. We hypothesised that the speciality of the attending physician (cardiologist or not) would affect the use of evidence-based strategies.

METHODS

Over a 3-month period (1st September to 30th November 1995), 3684 consecutive potential cases of acute myocardial infarction (AMI) in 20 adjacent hospitals in the Yorkshire Region were identified from coronary care registers, clinical coding and biochemistry records of cardiac enzyme assay requests. There were 2153 consecutive cases of AMI identified, of which 1643 patients were alive at discharge. We compared the admission use of aspirin and thrombolysis, and the use of aspirin, beta-blockers, angiotensin-converting enzyme (ACE) inhibitors and statins at discharge between cardiologists and other physicians.

RESULTS

AMI patients under the care of cardiologists are more likely to receive aspirin and thrombolysis on the day of their event and to be prescribed aspirin, beta-blockers and statins on discharge. After correction for contraindications to their use, the above findings were broadly confirmed.

DISCUSSION

Cardiologists are more likely than general physicians to use evidence-based treatment strategies recognised to improve AMI patient outcome. It is likely that this will translate into a reduction of mortality or other hard endpoints in patient outcomes.

Identifying acute myocardial infarction: effects on treatment and mortality, and implications for National Service Framework audit

BACKGROUND

The National Service Framework (NSF) for Coronary Heart Disease requires annual clinical audit of the care of patients with myocardial infarction, with little guidance on how to achieve these standards and monitor practice.

AIM

To assess which method of identification of acute myocardial infarction (AMI) cases is most suitable for NSF audit, and to determine the effect of the definition of AMI on the assessment of quality of care.

DESIGN

Observational study.

METHODS

Over a 3-month period, 2153 consecutive patients from 20 hospitals across the Yorkshire region, with confirmed AMI, were identified from coronary care registers, biochemistry records and hospital coding systems. The sensitivity and positive predictive value of AMI patient identification using clinical coding, biochemistry and coronary care registers were compared to a 'gold standard' (the combination of all three methods).

RESULTS

Of 3685 possible cases of AMI singled out by one or more methods, 2153 patients were identified as having a final diagnosis of AMI. Hospital coding revealed 1668 (77.5%) cases, with a demographic profile similar to that of the total cohort. Secondary preventative measures required for inclusion in NSF were also of broadly similar distribution. The sensitivities and positive predictive values for patient identification were substantially less in the cohorts identified through biochemistry and coronary care unit register. Patients fulfilling WHO criteria (n=1391) had a 30-day mortality of 15.9%, vs. 24.2% for the total cohort.

DISCUSSION

Hospital coding misses a substantial proportion (22.5%) of AMI cases, but without any apparent systematic bias, and thus provides a suitably representative and robust basis for NSF-related audit. Better still would be the routine use of multiple methods of case identification.

Poor prognosis of patients presenting with symptomatic myocardial infarction but without chest pain

OBJECTIVE

To describe the clinical features, prognosis, and treatment of patients presenting with atypical forms of acute myocardial infarction.

DESIGN

Consecutive cases of possible acute myocardial infarction were sought from coronary care registers, biochemistry records, and hospital management systems. Case notes were reviewed and predefined epidemiological and clinical variables were abstracted.

SETTING

20 adjacent hospitals in the former Yorkshire region.

PATIENTS

3684 consecutive cases of possible acute myocardial infarction admitted in a three month period were identified, of whom 2096 had a first episode of confirmed acute myocardial infarction.

RESULTS

20.2% of all patients admitted with an eventual diagnosis of acute myocardial infarction presented with symptoms other than chest pain. Compared with the group presenting with chest pain, these patients were older (76.6 v 69.1 years, p < 0.001), were more often women (54.6% v 35.3%, p < 0.001), and were more likely to have a history of heart failure (18.6% v 6.9%, p < 0.001). They had a higher 30 and 365 day mortality (49.2% and 61.0%, respectively) compared with patients presenting with chest pain (17.9% and 26.2%). In a Cox regression analysis the hazard ratio for presentation without chest pain was 1.60 (95% confidence interval 1.30 to 1.97) (p < 0.001) adjusted for age, heart rate, blood pressure, left ventricular impairment, and infarction with ST segment elevation as covariates. Importantly, they were also less likely to receive treatments with a proven ability to improve prognosis.

CONCLUSIONS

Atypical presentation of myocardial infarction without chest pain is common and associated with increased mortality. This may result in part from a failure to use beneficial treatment strategies.

Use of cumulative mortality data in patients with acute myocardial infarction for early detection of variation in clinical practice: observational study

OBJECTIVES

Use of cumulative mortality adjusted for case mix in patients with acute myocardial infarction for early detection of variation in clinical practice.

DESIGN

Observational study.

SETTING

20 hospitals across the former Yorkshire region.

PARTICIPANTS

All 2153 consecutive patients with confirmed acute myocardial infarction identified during three months.

MAIN OUTCOME MEASURES

Variable life-adjusted displays showing cumulative differences between observed and expected mortality of patients; expected mortality calculated from risk model based on admission characteristics of age, heart rate, and systolic blood pressure.

RESULTS

The performance of two individual hospitals over three months was examined as an example. One, the smallest district hospital in the region, had a series of 30 consecutive patients but had five more deaths than predicted. The variable life-adjusted display showed minimal variation from that predicted for the first 15 patients followed by a run of unexpectedly high mortality. The second example was the main tertiary referral centre for the region, which admitted 188 consecutive patients. The display showed a period of apparently poor performance followed by substantial improvement, where the plot rose steadily from a cumulative net lives saved of -4 to 7. These variations in patient outcome are unlikely to have been revealed during conventional audit practice.

CONCLUSIONS

Variable life-adjusted display has been integrated into surgical care as a graphical display of risk-adjusted survival for individual surgeons or centres. In combination with a simple risk model, it may have a role in monitoring performance and outcome in patients with acute myocardial infarction.

A simple benchmark for evaluating quality of care of patients following acute myocardial infarction

OBJECTIVE

To develop a simple risk model as a basis for evaluating care of patients admitted with acute myocardial infarction.

METHODS

From coronary care registers, biochemistry records and hospital management systems, 2153 consecutive patients with confirmed acute myocardial infarction were identified. With 30 day all cause mortality as the end point, a multivariable logistic regression model of risk was constructed and validated in independent patient cohorts. The areas under receiver operating characteristic curves were calculated as an assessment of sensitivity and specificity. The model was reapplied to a number of commonly studied subgroups for further assessment of robustness.

RESULTS

A three variable model was developed based on age, heart rate, and systolic blood pressure on admission. This produced an individual probability of death by 30 days (P(30)) where P(30) = 1/(1 + exp(-L(30))) and L(30) = -5.624 + (0.085 x age) + (0.014 x heart rate) - (0.022 x systolic blood pressure). The areas under the receiver operating characteristic curves for the reference and test cohorts were 0.79 (95% CI 0.76 to 0.82) and 0.76 (95% CI 0.72 to 0.79), respectively. To aid application of the model to routine clinical audit, a normogram relating observed mortality and sample size to the likelihood of a significant deviation from the expected 30 day mortality rate was constructed.

CONCLUSIONS

This risk model is simple, reproducible, and permits quality of care of acute myocardial infarction patients to be reliably evaluated both within and between centres.

The management of venous leg ulcers: a project to improve care

This article describes a two-year project to develop resources for the improvement of leg ulcer management. It was felt that an audit tool and complementary resources, such as a resource pack and implementation guide, could help practitioners to implement clinical guidelines on leg ulcer management in practice. The audit results from the pilot project are briefly described and discussed in terms of informing future work.

The Rate Constant for the Recombination Reaction Between CF3 and O2 Measured Between 2 and 110 Torr

The rate constant k

Cardiovascular disease risk factors in 5-year-old urban South African children--the Birth to Ten Study

BACKGROUND

A birth cohort study, the Birth to Ten (BTT) study, commenced in the greater Johannesburg/Soweto metropole in South Africa in 1990. The overall BTT project collected antenatal, birth and early development information on these children as well as information that could help identify factors related to the emergence of risk of cardiovascular diseases (CVDs) in children.

OBJECTIVE

To determine CVD risk profiles and their determinants in 5-year-old children living in an urban environment in South Africa.

METHODS

Demographic and birth characteristics were collected on a sample of 964 5-year-olds whose parents agreed for blood samples to be taken from their children. The children's height and weight were measured using standardised procedures; blood pressure (BP) was measured with a Dinamap Vital Signs Monitor, and a non-fasting blood sample was drawn for lipid determinations. Information on exposure to tobacco smoke and additional health-related data were obtained by interview.

RESULTS

No differences were found between the birth weight and gestational age of the 5-year-old CVD participants and the remainder of the children studied at birth. The systolic BP was significantly different between ethnic groups, with the BP of the black children significantly higher than that of the Indian and white children, while the diastolic BP of black children was also the highest. White children had the highest mean total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC) levels, significantly higher than those in the black community. The coloured children's TC level was also significantly lower than that of the whites, while the LDLC level of the Indian children was significantly higher than that of the blacks. Overall, 64% of the children were exposed to environmental tobacco smoke (ETS), with the white group having the lowest rate (45% exposed to ETS). The coloured children were most frequently exposed to ETS, with 40.6% having primary caregivers who smoked; of these children 42% lived in homes with two or more smokers.

CONCLUSIONS

Tobacco control legislation will protect South Africans against tobacco sales promotions. This will be the first step towards increasing the priority of chronic disease prevention, health promotion and appropriate care for chronic diseases and their risk factors on the South African health policy agenda. The groups of children that were studied carried differing but significant levels of CVD risk. This suggests that the promotion of a healthy lifestyle should start in childhood, and should target the risk factors found in each group.

Large-scale cDNA analysis reveals phased gene expression patterns during preimplantation mouse development

Little is known about gene action in the preimplantation events that initiate mammalian development. Based on cDNA collections made from each stage from egg to blastocyst, 25438 3′-ESTs were derived, and represent 9718 genes, half of them novel. Thus, a considerable fraction of mammalian genes is dedicated to embryonic expression. This study reveals profound changes in gene expression that include the transient induction of transcripts at each stage. These results raise the possibility that development is driven by the action of a series of stage-specific expressed genes. The new genes, 798 of them placed on the mouse genetic map, provide entry points for analyses of human and mouse developmental disorders.

Multidisciplinary discharge assessment of the medically and socially high-risk infant

Discharge from a neonatal intensive care unit (NICU) requires assessment, coordination, and possible intervention by a multidisciplinary team. The infant's health condition and the family's social situation must be considered before discharge to design a discharge plan for the child's long-term well-being. This article presents the neonatal discharge assessment tool (N-DAT) as a method to identify risks at the time of discharge. The tool offers specific recommendations for use with infants who are medically or socially high risk. The implications for the NICU team and for coordination with community providers are discussed.

The implementation of clinical practice guidelines for venous leg ulcers

Since publishing its guidelines on the management of venous leg ulcers last year, the RCN has worked steadily to implement and audit both the guidelines, and their impact.

An inverse relation between blood pressure and birth weight among 5 year old children from Soweto, South Africa

STUDY OBJECTIVE

To examine the relation between birth weight and blood pressure at 5 years in a cohort of South African children.

DESIGN

Prospective cohort study.

PARTICIPANTS

849 five year old children.

SETTING

Soweto, a sprawling urban area close to Johannesburg, South Africa, which was a designated residential area for people classified as "black" under apartheid legislation.

MAIN RESULTS

Systolic blood pressure at 5 years was inversely related to birthweight (r = -0.05, p = 0.0007), independent of current weight, height, gestational age, maternal age or socioeconomic status at 5 years. There was no relation between birth weight and diastolic blood pressure. After adjusting for current weight and height, there was a mean decline in systolic blood pressure of 3.4 mm Hg (95% confidence intervals 1.4, 5.3 mm Hg) for every 1000 g increase in birth weight.

CONCLUSIONS

These data from a disadvantaged urbanised community in Southern Africa extend the reported observations of an inverse relation between birth weight and systolic blood pressure. The study adds to the evidence that influences in fetal life and early childhood influence systolic blood pressure. Further research is required to assess whether efforts to reduce the incidence of low birthweight babies will attenuate the prevalence of hypertension in future generations.

Using a supervisory framework to support and evaluate a multiproject practice development programme

The paper describes a multiproject practice development programme undertaken over a period of 1 year. The background and development of the programme are outlined, whilst attention is paid to the innovatory nature of the work, particularly the use of inductive, deductive and integrated approaches to both change implementation and project supervision. The programme was monitored throughout using different data sources and the paper uses evaluative material retrospectively to provide answers to organizational and professional difficulties which arose during the course of the programme. The authors conclude that the use of combinations of different models for practice development has potential, but requires careful supervision. They also recommend that those involved in practice development are made fully aware of its local or micropolitics, and develop strategies to deal with change before it occurs, not after it has taken place.

Biologically erodable microspheres as potential oral drug delivery systems

Biologically adhesive delivery systems offer important advantages over conventional drug delivery systems. Here we show that engineered polymer microspheres made of biologically erodable polymers, which display strong adhesive interactions with gastrointestinal mucus and cellular linings, can traverse both the mucosal absorptive epithelium and the follicle-associated epithelium covering the lymphoid tissue of Peyer's patches. The polymers maintain contact with intestinal epithelium for extended periods of time and actually penetrate it, through and between cells. Thus, once loaded with compounds of pharmacological interest, the microspheres could be developed as delivery systems to transfer biologically active molecules to the circulation. We show that these microspheres increase the absorption of three model substances of widely different molecular size: dicumarol, insulin and plasmid DNA.

Practitioner based quality improvement: a review of the Royal College of Nursing's dynamic standard setting system

OBJECTIVE

To explore and describe the implementation of the Royal College of Nursing's approach to audit--the dynamic standard setting system--within the current context of health care, in particular to focus on how the system has developed since its inception in the 1980s as a method for uniprofessional and multiprofessional audit.

DESIGN

Qualitative design with semistructure interviews and field visits.

SETTING

28 sites throughout the United Kingdom that use the dynamic standard setting system.

SUBJECTS

Quality and audit coordinators with a responsibility for implementing the system; clinical staff who practice the system.

MAIN MEASURES

Experiences of the dynamic standard setting system, including reasons for selection, methods of implementation, and observed outcomes.

RESULTS

Issues relating to four themes emerged from the data: practical experiences of the system as a method for improving patient care; issues of facilitation and training; strategic issues of implementation; and the use of the system as a method for multiprofessional audit. The development of clinical practice was described as a major benefit of the system and evidence of improved patient care was apparent. However, difficulties were experienced in motivating staff and finding time for audit, which in part related to the current format of the system and the level of training and support available for clinical staff. Diverse experiences were reported in the extent to which the system had been integrated at a strategic level of quality improvement and its successful application to multiprofessional clinical audit.

CONCLUSIONS

The Royal College of Nursing's dynamic standard setting system can successfully be used as a method for clinical audit at both a uniprofessional and multiprofessional level. However, to capitalise on the strengths of the system, several issues need to be considered further. These include modifications to the system itself, as well as a more strategic focus on resources and support for audit, better integration of quality initiatives in health care, and a continuing focus on ways to achieve true multiprofessional collaboration and involvement of patients in clinical audit.

Clinical audit makes progress in care and teamwork

Clinical audit should be about improving the delivery of care to patients as well as promoting multidisciplinary working in clinical teams. For clinical audit to move forward it must relate to, and be integrated with, four key areas: clinical effectiveness, the contracting process, patient-focused care and the development of clinical teams. This article discusses how users of health services can be helped to participate fully in clinical audit and its role in enhancing professional development of team members.

Enhancing Nurses' Reliance on Patients' Perceptions of Pain During Pain Assessment: A Comparison of Two Educational Methods

The purpose of this quasi-experimental study was to determine if an educational program on pain assessment that includes both knowledge and attitude domains is more effective than a didactic educational offering in encouraging nurses' reliance on patients' self-reports of pain during assessment for pain. Twenty-two registered nurses and seven licensed practical nurses at the Tucson Veterans Affairs Medical Center participated. Group A received a lecture and watched a videotape. Group B received a lecture, watched a videotape, and participated in a group discussion on attitudes. Participants in both groups completed the Pain Management Questionnaire developed by Ferrell, Eberts, McCaffery & Grant (1991). No significant differences were found between groups with respect to results on the pain management questionnaire.

Behavioral treatment for the anticipatory nausea and vomiting induced by cancer chemotherapy

The nausea and vomiting experienced by one in four cancer patients in anticipation of chemotherapy is probably a learned response to treatment. To determine whether behavioral approaches for altering learned responses might be useful treatments for these symptoms, we compared the effects of "systematic desensitization" (a behavioral treatment in which relaxation is learned as a response to situations in which patients have had anticipatory nausea and vomiting) with those of counseling and of no treatment. Sixty ambulatory cancer patients with anticipatory nausea and vomiting before their third and fourth chemotherapy treatments were randomized equally to the three groups. Significantly more patients receiving desensitization reported no anticipatory nausea before their fifth and sixth chemotherapy treatments than patients given counseling (P less than 0.05) or no treatment (P less than 0.01). Desensitized patients also reported significantly less severe anticipatory nausea (P less than 0.01) and vomiting (P less than 0.05) and a shorter duration of anticipatory nausea (P less than 0.01). We conclude that systematic desensitization appears to have an antiemetic effect in cancer patients who receive chemotherapy, and may be useful in the management of these problems.