Thrombin-activatable fibrinolysis inhibitor in human abdominal aortic aneurysm disease.

Essentials Patients with abdominal aortic aneurysms (AAA) develop dense clots that are resistant to lysis. This study explores the role of thrombin-activatable fibrinolysis inhibitor (TAFI) in human AAA. There is evidence of chronically increased TAFI activation in patients with AAA. TAFI may represent a pharmacological target for cardiovascular risk reduction in AAA. SUMMARY: Background Intra-luminal thrombosis is a key factor in growth of abdominal aortic aneurysms (AAAs). Patients with AAA form dense clots that are resistant to fibrinolysis. Thrombin-activatable fibrinolysis inhibitor (TAFI) has been shown to influence AAA development in murine models. Objective The aim of this study is to characterize the role of TAFI in human AAA. Methods Plasma levels of TAFI, TAFI activation peptide (TAFI-AP), activated/inactivated TAFI (TAFIa/ai) and plasmin-α2-antiplasmin complex were measured by ELISAs in patients with AAA (n = 202) and controls (n = 188). Results TAFIa/ai and TAFI-AP levels were higher in patients than controls (median [IQR], 20.3 [14.6-32.8] ng mL-1 vs. 14.2 [11.2-19.3] ng mL-1 and 355.0 [232.4-528.1] ng mL-1 vs. 248.6 [197.1-328.1] ng mL-1 ). TAFIa/ai was positively correlated with TAFI-AP (r = 0.164). Intact TAFI levels were not different between patients and controls (13.4 [11.2-16.1] µg mL-1 vs. 12.8 [10.6-15.4] µg mL-1 ). Plasmin-α2-antiplasmin was higher in AAA patients than controls (690.0 [489.1-924.3] ng mL-1 vs. 480.7 [392.6-555.3] ng mL-1 ). Conclusions The increase in TAFIa/ai and TAFI-AP suggests an increased TAFI activation in patients with AAA. Prospective studies are required to further elucidate the role of TAFI and fibrinolysis in AAA pathogenesis.

Aspirin therapy is associated with less compact fibrin networks and enhanced fibrinolysis in patients with abdominal aortic aneurysm.

OBJECTIVE: Thrombotic changes in fibrin networks contribute to increased cardiovascular risk in patients with abdominal aortic aneurysm (AAA). Given that aspirin modulates the fibrin network, we aimed to determine if aspirin therapy is associated with changes in ex-vivo fibrin clot characteristics in AAA patients and also conducted an exploratory analysis of 5-year mortality in these individuals. METHODS: We recruited 145 male patients, divided into controls (aortic diameter < 3 cm, n = 49), AAA not taking aspirin (AAA-Asp, n = 50) and AAA on 75 mg day(-1) aspirin (AAA+Asp, n = 46), matched for aneurysm size. Characteristics of clots made from plasma and plasma-purified fibrinogen were investigated using turbidimetric analysis, permeation studies, and confocal and electron microscopy. Plasma fibrinogen, D-dimer and inflammatory marker levels were also measured. RESULTS: Maximum absorbance (MA) of plasma clots from controls was lower than that of AAA patients not on aspirin (AAA-Asp) at 0.30 ± 0.01 and 0.38 ± 0.02 au, respectively (P = 0.002), whereas aspirin-treated subjects had MA similar to controls (0.31 ± 0.02 P = 0.9). Plasma clot lysis time displayed an identical pattern at 482 ± 15, 597 ± 24 and 517 ± 27 s for control, AAA-Asp and AAA+Asp (P = 0.001 and P = 0.8). The lysis time of clots made from purified fibrinogen of AAA-Asp was longer than that of AAA+Asp patients (756 ± 47 and 592 ± 52 s, respectively; P = 0.041). Permeation studies and confocal and electron microscopy showed increased clot density in AAA-Asp compared with the AAA+Asp group. Mortality in AAA-Asp and AAA+Asp was similar, despite increased cardiovascular risk in the latter group, and both exhibited higher mortality than controls. CONCLUSION: Aspirin improves fibrin clot characteristics in patients with AAA, which may have important clinical implications.

Cardiovascular risk in patients with small and medium abdominal aortic aneurysms, and no history of cardiovascular disease.

BACKGROUND: Cardiovascular disease (CVD) is the main cause of death in people with abdominal aortic aneurysm (AAA). There is little evidence that screening for AAA reduces all-cause or cardiovascular mortality. The aim of the study was to assess whether subjects with a small or medium AAA (3·0-5·4 cm), without previous history of clinical CVD, had raised levels of CVD biomarkers or increased total mortality. METHODS: This prospective study included subjects with a small or medium AAA and controls, all without a history of clinical CVD. CVD biomarkers (high-sensitivity C-reactive protein, hs-CRP; heart-type fatty acid-binding protein, H-FABP) were measured, and survival was recorded. RESULTS: Of a total of 815 people, 476 with an AAA and 339 controls, a cohort of 86 with small or medium AAA (3-5·4 cm) and 158 controls, all with no clinical history of CVD, were identified. The groups were matched for age and sex. The AAA group had higher median (i.q.r.) levels of hs-CRP (2·8 (1·2-6·0) versus 1·3 (0·5-3·5) mg/l; P < 0·001) and H-FABP (4·6 (3·5-6·0) versus 4·0 (3·3-5·1) µg/l; P = 0·011) than controls. Smoking was more common in the AAA group; however, hs-CRP and H-FABP levels were not related to smoking. Mean survival was lower in the AAA group: 6·3 (95 per cent confidence interval (c·i.) 5·6 to 6·9) years versus 8·0 (7·6 to 8·1) years in controls (P < 0·001). Adjusted mortality was higher in the AAA group (hazard ratio 3·41, 95 per cent c·i. 2·11 to 9·19; P < 0·001). CONCLUSION: People with small or medium AAA and no clinical symptoms of CVD have higher levels of hs-CRP and H-FABP, and higher mortality compared with controls. They should continue to receive secondary prevention against CVD.

NAD(+) and axon degeneration revisited: Nmnat1 cannot substitute for Wld(S) to delay Wallerian degeneration.

The slow Wallerian degeneration protein (Wld(S)), a fusion protein incorporating full-length nicotinamide mononucleotide adenylyltransferase 1 (Nmnat1), delays axon degeneration caused by injury, toxins and genetic mutation. Nmnat1 overexpression is reported to protect axons in vitro, but its effect in vivo and its potency remain unclear. We generated Nmnat1-overexpressing transgenic mice whose Nmnat activities closely match that of Wld(S) mice. Nmnat1 overexpression in five lines of transgenic mice failed to delay Wallerian degeneration in transected sciatic nerves in contrast to Wld(S) mice where nearly all axons were protected. Transected neurites in Nmnat1 transgenic dorsal root ganglion explant cultures also degenerated rapidly. The delay in vincristine-induced neurite degeneration following lentiviral overexpression of Nmnat1 was significantly less potent than for Wld(S), and lentiviral overexpressed enzyme-dead Wld(S) still displayed residual neurite protection. Thus, Nmnat1 is significantly weaker than Wld(S) at protecting axons against traumatic or toxic injury in vitro, and has no detectable effect in vivo. The full protective effect of Wld(S) requires more N-terminal sequences of the protein.

Autoradiographic localization of (125)i[Tyr(14)] nociceptin/orphanin FQ binding sites in macaque primate CNS.

Nociceptin/orphanin FQ (N/OFQ) is a recently identified neuropeptide that has been implicated in a multitude of CNS functions. These include nociception, feeding, cognition, locomotion, stress and neuroendocrine control. The endogenous receptor for this ligand is the nociceptin/orphanin FQ peptide (NOP) receptor. The distribution of NOP in rodent has been widely reported by the use of in situ hybridization, immunohistochemistry and autoradiographic radioligand binding but less is known of its localization in higher species. We have therefore sought to optimize and determine the distribution of (125)I[Tyr(14)]N/OFQ binding sites in macaque primate brain and spinal cord. Highest levels of binding were observed in neocortical areas, hippocampus, amygdala, caudate nucleus and putamen, medial thalamic nuclei and superficial laminae of the superior colliculus. These novel data present for the first time, the distribution of N/OFQ receptors in non-human primate CNS and, by comparison with localization in the rat, reveal that species differences may exist in the distribution of this neuropeptide receptor. These data have important implications regarding the roles of N/OFQ across species and may have ramifications in the interpretation of preclinical pharmacological studies.

Ultra-thin-polysiloxane-film-composite membranes for the optimisation of amperometric oxidase enzyme electrodes.

An outer ultra-thin-polydimethyldichlorosiloxane film composite membrane has been used as the outer covering barrier in an amperometric glucose oxidase enzyme electrode biosensor. The composite membrane was formed via the condensation polymerisation of dimethyldichlorosilane at the surface of a host porous alumina membrane. Homogeneous polydimethyldichlorosiloxane films of <100 nm thickness acted as effective substrate diffusional barriers and were supported by the underlying porous alumina surface. Glucose and oxygen permeability coefficients were determined using diffusion chamber apparatus. Polysiloxane composite membranes were found to offer some screening functionality towards anionic biological interferents such as ascorbate. On exposure to blood an approximate 25% signal drift was observed during the first 2 h exposure to blood; after this time responses remained almost stable. Whole blood glucose determinations showed a close correlation (r(2)=0.98) to analyses performed via standard hospital analyses.

beta-adrenergic receptor population is up-regulated by increased cyclic adenosine monophosphate concentration in chicken skeletal muscle cells in culture.

Skeletal muscle hypertrophy is promoted in vivo by administration of beta-adrenergic receptor (betaAR) agonists. Chicken skeletal muscle cells were treated with 1 microM isoproterenol, a strong betaAR agonist, between days 7 and 10 in culture. betaAR population increased by approximately 40% during this treatment; however, the ability of the cells to synthesize cyclic adenosine monophosphate (cAMP) was diminished by twofold. Neither the basal concentration of cAMP nor the quantity of myosin heavy chain (MHC) was affected by the 3-d exposure to isoproterenol. To understand further the relationship between intracellular cAMP levels, betaAR population, and muscle protein accumulation, intracellular cAMP levels were artificially elevated by treatment with 0-10 betaM forskolin for 3 d. The basal concentration of cAMP in forskolin-treated cells increased up to sevenfold in a dose-dependent manner. Increasing concentrations of forskolin also led to an increase in betaAR population, with a maximum increase of approximately 40-60% at 10 microM forskolin. A maximum increase of 40-50% in the quantity of MHC was observed at 0.2 microM forskolin, but higher concentrations of forskolin reduced the quantity of MHC back to control levels. At 0.2 microM forskolin, intracellular levels of cAMP were higher by approximately 35%, and the betaAR population was higher by approximately 30%. Neither the number of muscle nuclei fused into myotubes nor the percentage of nuclei in myotubes was affected by forskolin at any of the concentrations studied.

Effect of electrical stimulation on beta-adrenergic receptor population and cyclic amp production in chicken and rat skeletal muscle cell cultures.

Expression of the beta-adrenergic receptor (betaAR) and its coupling to cyclic AMP (cAMP) synthesis are important components of the signaling system that controls muscle atrophy and hypertrophy, and the goal of this study was to determine if electrical stimulation in a pattern simulating slow muscle contraction would alter the betaAR response in primary cultures of avian and mammalian skeletal muscle cells. Specifically, chicken skeletal muscle cells and rat skeletal muscle cells that had been grown for 7 d in culture were subjected to electrical stimulation for an additional 2 d at a pulse frequency of 0.5 pulses/sec and a pulse duration of 200 msec. In chicken skeletal muscle cells, the betaAR population was not significantly affected by electrical stimulation; however, the ability of these cells to synthesize cyclic AMP was reduced by approximately one-half. In contrast, the betaAR population in rat muscle cells was increased slightly but not significantly by electrical stimulation, and the ability of these cells to synthesize cyclic AMP was increased by almost twofold. The basal levels of intracellular cyclic AMP in neither rat muscle cells nor chicken muscle cells were affected by electrical stimulation.

Career structures for South Australian nurses: developing a research agenda.

Career structure models are central to the organisation of the work of professionals like nurses, to their remuneration and other forms of recognition, and for the organisation of employing institutions. It has been little more than a decade since the implementation of a career structure model for nurses in South Australia in 1986-7. Since that time a number of changes to the profession, and to the health care system more generally, have resulted in ad hoc adaptations to, and sometimes an erosion of, the career structure as originally envisioned. As we approach the new millennium, an assessment and evaluation of the efficacy of the SA career structure in meeting the professional needs of nurses and their employing organisations is both timely and necessary. This paper provides the historical background to the development of the SA career structure, and highlights some of the major issues that have emerged as problematic since implementation. The paper then identifies some issues that might contribute towards guiding a more systematic approach to the re-appraisal of nurses' career structures.

Beta-adrenergic receptor gene expression in bovine skeletal muscle cells in culture.

Beta-adrenergic receptors (betaAR) are abundant in fetal, neonatal, and adult skeletal muscles of cattle; however, only minimal levels of functional betaAR were detected in multinucleated muscle cell cultures prepared from 90- to 150-d fetal bovine skeletal muscle. Two other lines of evidence were consistent with low levels of betaAR expression in bovine muscle cultures. First, treating the cells with 10(-6)M isoproterenol for up to 20 min did not increase intracellular cAMP concentration. Second, neither the quantity of myosin heavy chain (MHC) nor its apparent synthesis rate were changed by treating the cells for 4 d with 10(-7) or 10(-6) M isoproterenol. Despite these results, the mRNA for the beta2AR could be detected in muscle cultures by PCR and on slot blots. Thus, the beta2AR mRNA was expressed, but significant levels of functional receptors could not be detected. Glucocorticoids are known to activate expression of OAR genes in several tissues, and the effect of dexamethasone on OAR gene expression in bovine multinucleated muscle cell cultures was evaluated. The intracellular concentration of cAMP following treatment with isoproterenol was elevated 10-fold by dexamethasone, and the population of functional receptors was elevated by approximately 50%. The effect of dexamethasone on muscle protein synthesis and accumulation was analyzed after pretreating the cells with dexamethasone for 24 h, followed by treatment with dexamethasone and 10(-6)M isoproterenol for an additional 48 h. The quantity of MHC synthesized and the apparent synthesis rate of MHC were stimulated by 10 to 35%. These effects seem to be due to posttranscriptional events, because the quantity of beta2AR receptor mRNA on slot blots was not increased by treatment with dexamethasone. Results of this study emphasize the importance of verifying that muscle cells contain functional betaAR when they are used to study the effects of betaAR agonists on muscle protein metabolism.