Outcomes of ruptured abdominal aortic aneurysm

Ruptured abdominal aortic aneurysm (RAAA) is a life-threatening event, and without operative treatment the patient will die. The overall mortality can be as high as 80-90%; thus repair of RAAA should be attempted whenever feasible. The quality of life (QoL) has become an increasingly important outcome measure in vascular surgery. Aim of the study was to evaluate outcomes of RAAA and to find out predictors of mortality. In Helsinki and Uusimaa district 626 patients were identified to have RAAA in 1996-2004. Altogether 352 of them were admitted to Helsinki University Central Hospital (HUCH). Based on Finnvasc Registry, 836 RAAA patients underwent repair of RAAA in 1991-1999. The 30-day operative mortality, hospital and population-based mortality were assessed, and the effect of regional centralisation and improving in-hospital quality on the outcome of RAAA. QoL was evaluated by a RAND-36 questionnaire of survivors of RAAA. Quality-adjusted life years (QALYs), which measure length and QoL, were calculated using the EQ-5D index and estimation of life expectancy. The predictors of outcome after RAAA were assessed at admission and 48 hours after repair of RAAA. The 30-day operative mortality rate was 38% in HUCH and 44% nationwide, whereas the hospital mortality was 45% in HUCH. Population-based mortality was 69% in 1996-2004 and 56% in 2003-2004. After organisational changes were undertaken, the mortality decreased significantly at all levels. Among the survivors, the QoL was almost equal when compared with norms of age- and sex-matched controls; only physical functioning was slightly impaired. Successful repair of RAAA gave a mean of 4.1 (0-30.9) QALYs for all RAAA patients, although non-survivors were included. The preoperative Glasgow Aneurysm Score was an independent predictor of 30-day operative mortality after RAAA, and it also predicted the outcome at 48- hours for initial survivors of repair of RAAA. A high Glasgow Aneurysm Score and high age were associated with low numbers of QALYs to be achieved. Organ dysfunction measured by the Sequential Organ Failure Assessment (SOFA) score at 48 hours after repair of RAAA was the strongest predictor of death. In conclusion surgery of RAAA is a life-saving and cost-effective procedure. The centralisation of vascular emergencies improved the outcome of RAAA patients. The survivors had a good QoL after RAAA. Predictive models can be used on individual level only to provide supplementary information for clinical decision-making due to their moderate discriminatory value. These results support an active operation policy, as there is no reliable measure to predict the outcome after RAAA.

Surveillance of Surgical Site Infections following Major Hip and Knee Surgery in Finland

Background and aims. Since 1999, hospitals in the Finnish Hospital Infection Program (SIRO) have reported data on surgical site infections (SSI) following major hip and knee surgery. The purpose of this study was to obtain detailed information to support prevention efforts by analyzing SIRO data on SSIs, to evaluate possible factors affecting the surveillance results, and to assess the disease burden of postoperative prosthetic joint infections in Finland. Methods. Procedures under surveillance included total hip (THA) and total knee arthroplasties (TKA), and the open reduction and internal fixation (ORIF) of femur fractures. Hospitals prospectively collected data using common definitions and written protocol, and also performed postdischarge surveillance. In the validation study, a blinded retrospective chart review was performed and infection control nurses were interviewed. Patient charts of deep incisional and organ/space SSIs were reviewed, and data from three sources (SIRO, the Finnish Arthroplasty Register, and the Finnish Patient Insurance Centre) were linked for capture-recapture analyses. Results. During 1999-2002, the overall SSI rate was 3.3% after 11,812 orthopedic procedures (median length of stay, eight days). Of all SSIs, 56% were detected after discharge. The majority of deep incisional and organ/space SSIs (65/108, 60%) were detected on readmission. Positive and negative predictive values, sensitivity, and specificity for SIRO surveillance were 94% (95% CI, 89-99%), 99% (99-100%), 75% (56-93%), and 100% (97-100%), respectively. Of the 9,831 total joint replacements performed during 2001-2004, 7.2% (THA 5.2% and TKA 9.9%) of the implants were inserted in a simultaneous bilateral operation. Patients who underwent bilateral operations were younger, healthier, and more often males than those who underwent unilateral procedures. The rates of deep SSIs or mortality did not differ between bi- and uni-lateral THAs or TKAs. Four deep SSIs were reported following bilateral operations (antimicrobial prophylaxis administered 48-218 minutes before incision). In the three registers, altogether 129 prosthetic joint infections were identified after 13,482 THA and TKA during 1999-2004. After correction with the positive predictive value of SIRO (91%), a log-linear model provided an estimated overall prosthetic joint infection rate of 1.6% after THA and 1.3% after TKA. The sensitivity of the SIRO surveillance ranged from 36% to 57%. According to the estimation, nearly 200 prosthetic joint infections could occur in Finland each year (the average from 1999 to 2004) after THA and TKA. Conclusions. Postdischarge surveillance had a major impact on SSI rates after major hip and knee surgery. A minority of deep incisional and organ/space SSIs would be missed, however, if postdischarge surveillance by questionnaire was not performed. According to the validation study, most SSIs reported to SIRO were true infections. Some SSIs were missed, revealing some weakness in case finding. Variation in diagnostic practices may also affect SSI rates. No differences were found in deep SSI rates or mortality between bi- and unilateral THA and TKA. However, patient materials between these two groups differed. Bilateral operations require specific attention paid to their antimicrobial prophylaxis as well as to data management in the surveillance database. The true disease burden of prosthetic joint infections may be heavier than the rates from national nosocomial surveillance systems usually suggest.

Pathobiological Aspects of Nonreheumatic Aortic Valve Stenosis

Aortic valve stenosis (AS) is an active disease process akin to atherosclerosis, with chronic inflammation, lipid accumulation, extracellular matrix remodeling, fibrosis, and extensive calcification of the valves being characteristic features of the disease. The detailed mechanisms and pathogenesis of AS are still incompletely understood, however, and pharmacological treatments targeted toward components of the disease are not currently available. In this thesis project, my coworkers and I studied stenotic aortic valves obtained from 86 patients undergoing valve replacement for clinically significant AS. Non-stenotic control valves (n=17) were obtained from patients undergoing cardiac transplantation or from organ donors without cardiac disease. We identified a novel inflammatory factor, namely mast cell, in stenotic aortic valves and present evidence showing that this multipotent inflammatory cell may participate in the pathogenesis of AS. Using immunohistochemistry and double immunofluorescence stainings, we found that a considerable number of mast cells accumulate in stenotic valves and, in contrast to normal valves, the mast cells in diseased valves were in an activated state. Moreover, valvular mast cells contained two effective proteases, chymase and cathepsin G, which may participate in adverse remodeling of the valves either by inducing fibrosis (chymase and cathepsin G) or by degrading elastin fibers in the valves (cathepsin G). As chymase and cathepsin G are both capable of generating the profibrotic peptide angiotensin II, we also studied the expression and activity of angiotensin-converting enzyme (ACE) in the valves. Using RT-PCR, imunohistochemistry, and autoradiography, we observed a significant increase in the expression and activity of ACE in stenotic valves. Besides mast cell-derived cathepsin G, aortic valves contained other elastolytic cathepsins (S, K, and V). Using immunohistochemistry, RT-PCR, and fluorometric microassay, we showed that the expression and activity of these cathepsins were augmented in stenotic valves. Furthermore, in stenotic but not in normal valves, we observed a distinctive pattern of elastin fiber degradation and disorganization. Importantly, this characteristic elastin degradation observed in diseased valves could be mimicked by adding exogenous cathepsins to control valves, which initially contained intact elastin fibers. In stenotic leaflets, the collagen/elastin ratio was increased and correlated positively with smoking, a potent AS-accelerating factor. Indeed, cigarette smoke could also directly activate cultured mast cells and fibroblasts. Next, we analyzed the expression and activity of neutral endopeptidase (NEP), which parallels the actions of ACE in degrading bradykinin (BK) and thus inactivates antifibrotic mechanisms in tissues. Real-time RT-PCR and autoradiography revealed NEP expression and activity to be enhanced in stenotic valves compared to controls. Furthermore, both BK receptors (1 and 2) were present in aortic valves and upregulated in stenotic leaflets. Isolated valve myofibroblasts expressed NEP and BK receptors, and their upregulation occurred in response to inflammation. Finally, we observed that the complement system, a source of several proinflammatory mediators and also a potential activator of valvular mast cells, was activated in stenotic valves. Moreover, receptors for the complement-derived effectors C3a and C5a were expressed in aortic valves and in cultured aortic valve myofibroblasts, in which their expression was induced by inflammation as well as by cigarette smoke. In conclusion, our findings revealed several novel mechanisms of inflammation (mast cells and mast cell-derived mediators, complement activation), fibrosis (ACE, chymase, cathepsin G, NEP), and elastin fiber degradation (cathepsins) in stenotic aortic valves and highlighted these effectors as possible pathogenic contributors to AS. These results support the notion of AS as an active process with inflammation and extracellular matrix remodeling as its key features and identify possible new targets for medical therapy in AS.

Bone Health in Children and Adolescents with Juvenile Idiopathic Arthritis and Solid Organ Transplant

Osteoporosis is a skeletal disorder characterized by compromised bone strength that predisposes to increased fracture risk. Childhood and adolescence are critical periods for bone mass gain. Peak bone mass is mostly acquired by the age of 18 years and is an important determinant of adult bone health and lifetime risk for fractures. Medications, especially glucocorticoids (GCs), chronic inflammation, decreased physical activity, hormonal deficiencies, delayed puberty, and poor nutrition may predispose children and adolescents with a chronic disease to impaired bone health. In this work, we studied overall bone health, the incidence and prevalence of fractures in children and adolescents who were treated for juvenile idiopathic arthritis (JIA) or had undergone solid organ transplantation. The first study cohort included 62 patients diagnosed with JIA and treated with GCs. The epidemiology of fractures after transplantation was investigated in 196 patients and a more detailed analysis of bone health determinants was performed on 40 liver (LTx) and 106 renal (RTx) transplantation patients. Bone mineral density (BMD) and vertebral morphology were assessed by dual-energy x-ray absorptiometry. Standard radiographs were obtained to detect vertebral fractures and to determine bone age; BMD values were adjusted for skeletal maturity. Our study showed that median BMD values were subnormal in all patient cohorts. The values were highest in patients with JIA and lowest in patients with LTx. Age at transplantation influenced BMD values in LTx but not RTx patients; BMD values were higher in patients who had LTx before the age of two years. BMD was lowest during the immediate posttransplantation years and increased subnormally during puberty. Delayed skeletal maturation was common in all patient groups. The prevalence of vertebral fractures ranged from 10% to 19% in the cohorts. Most of the fractures were asymptomatic and diagnosed only at screening. Vertebral fractures were most common in LTx patients. Vitamin D deficiency was common in all patient groups, and only 3% of patients with JIA and 25% of transplantation patients were considered to have adequate serum vitamin D levels. The total cumulative weight-adjusted dose of GC was not associated with BMD values in JIA or LTx patients. The combination of female gender and age over 15 years, parathyroid hormone concentration over 100 ng/L, and cumulative weight-adjusted methylprednisolone dose over 150 mg/kg during the three preceding years were found to be important predictors for low lumbar spine BMD in RTx patients. Based on the high prevalence of osteoporosis in the study cohorts more efforts should be put to prevention and early diagnosis of osteoporosis in these pediatric patients.

Preparation of reticulated MAX-phase support with morphology-controllable nanostructured ceria coating for gas exhaust catalyst devices

Reticulated porous Ti3AlC2 ceramic, a member of the MAX-phase family (Mn+1AXn phases, where M is an early transition metal, A is an A-group element, and X is carbon and/or nitrogen), was prepared from the highly dispersed aqueous suspension by a replica template method. Through a cathodic electrogeneration method, nanocrystalline catalytic CeO2 coatings were deposited on the conductive porous Ti 3AlC2 supports. By adjusting the pH value and cathodic deposition current, coatings exhibiting nanocellar, nanosheets-like, or bubble-free morphologies can be obtained. This work expects to introduce a novel practically feasible material system and a catalytic coating preparation technique for gas exhaust catalyst devices.

Kallikrein-related peptidase 4 induces tumour microenvironment alterations that support tumour growth

Kallikrein-related peptidase 4 (KLK4) is a protease with elevated production in prostate cancer versus benign tissue. KLK4 expression is associated with prostate cancer risk, and its activity favours tumour progression through increasing cell motility and growth. Importantly, over-production of KLK4 in prostate glandular cells precedes tumour formation, positioning the enzyme to play a role in early remodelling of the tumour microenvironment, a process essential for tumour growth. We sought to identify the proteins and downstream signalling pathways targeted by KLK4 activity, to define its role in tumour microenvironment remodelling and evaluate the efficacy of KLK4 inhibition as a cancer therapy.

Conceptualising social media support for tacit knowledge sharing: physicians’ perspectives and experiences

Purpose – This paper aims to explore the potential contributions of social media in supporting tacit knowledge sharing, according to the physicians’ perspectives and experiences. Design/methodology/approach – Adopting a qualitative survey design, 24 physicians were interviewed. Purposive and snowball sampling were used to select the participants. Thematic analysis approach was used for data analysis. Findings – The study revealed five major themes and over 20 sub-themes as potential contributions of social media to tacit knowledge flow among physicians. The themes included socialising, practising, networking, storytelling and encountering. In addition, with the help of the literature and the supporting data, the study proposed a conceptual model that explains the potential contribution of social media to tacit knowledge sharing. Research limitations/implications – The study had both theoretical (the difficulty of distinguishing tacit and explicit knowledge in practice) and practical limitations (small sample size). The study findings have implications for the healthcare industry whose clinical teams are not always physically co-located but must exchange their critical experiential and tacit knowledge. Originality/value – The study has opened up a new discussion of this area by demonstrating and conceptualising how social media tools may facilitate tacit knowledge sharing.

Cluster based training for scaling non-linear support vector machines

Support Vector Machines(SVMs) are hyperplane classifiers defined in a kernel induced feature space. The data size dependent training time complexity of SVMs usually prohibits its use in applications involving more than a few thousands of data points. In this paper we propose a novel kernel based incremental data clustering approach and its use for scaling Non-linear Support Vector Machines to handle large data sets. The clustering method introduced can find cluster abstractions of the training data in a kernel induced feature space. These cluster abstractions are then used for selective sampling based training of Support Vector Machines to reduce the training time without compromising the generalization performance. Experiments done with real world datasets show that this approach gives good generalization performance at reasonable computational expense.

MAC design for heterogeneous application support in OFDM based wireless systems

With the increasing adoption of wireless technology, it is reasonable to expect an increase in file demand for supporting both real-time multimedia and high rate reliable data services. Next generation wireless systems employ Orthogonal Frequency Division Multiplexing (OFDM) physical layer owing, to the high data rate transmissions that are possible without increase in bandwidth. Towards improving file performance of these systems, we look at the design of resource allocation algorithms at medium-access layer, and their impact on higher layers. While TCP-based clastic traffic needs reliable transport, UDP-based real-time applications have stringent delay and rate requirements. The MAC algorithms while catering to the heterogeneous service needs of these higher layers, tradeoff between maximizing the system capacity and providing fairness among users. The novelly of this work is the proposal of various channel-aware resource allocation algorithms at the MAC layer. which call result in significant performance gains in an OFDM based wireless system.

OCR Prediction Using Support Vector Machine Based on Piezocone Data

The determination of the overconsolidation ratio (OCR) of clay deposits is an important task in geotechnical engineering practice. This paper examines the potential of a support vector machine (SVM) for predicting the OCR of clays from piezocone penetration test data. SVM is a statistical learning theory based on a structural risk minimization principle that minimizes both error and weight terms. The five input variables used for the SVM model for prediction of OCR are the corrected cone resistance (qt), vertical total stress (sigmav), hydrostatic pore pressure (u0), pore pressure at the cone tip (u1), and the pore pressure just above the cone base (u2). Sensitivity analysis has been performed to investigate the relative importance of each of the input parameters. From the sensitivity analysis, it is clear that qt=primary in situ data influenced by OCR followed by sigmav, u0, u2, and u1. Comparison between SVM and some of the traditional interpretation methods is also presented. The results of this study have shown that the SVM approach has the potential to be a practical tool for determination of OCR.

Water management capacity building to support rapidly developing mining economies

Many developing countries are experiencing rapid expansion in mining with associated water impacts. In most cases mining expansion is outpacing the building of national capacity to ensure that sustainable water management practices are implemented. Since 2011, Australia's International Mining for Development Centre (IM4DC) has funded capacity building in such countries including a program of water projects. Five projects in particular (principally covering experiences from Peru, Colombia, Ghana, Zambia, Indonesia, Philippines and Mongolia) have provided insight into water capacity building priorities and opportunities. This paper reviews the challenges faced by water stakeholders, and proposes the associated capacity needs. The paper uses the evidence derived from the IM4DC projects to develop a set of specific capacity-building recommendations. Recommendations include: the incorporation of mine water management in engineering and environmental undergraduate courses; secondments of staff to suitable partner organisations; training to allow site staff to effectively monitor water including community impacts; leadership training to support a water stewardship culture; training of officials to support implementation of catchment management approaches; and the empowerment of communities to recognise and negotiate solutions to mine-related risks. New initiatives to fund the transfer of multi-disciplinary knowledge from nations with well-developed water management practices are called for.