Damjan Kovač

Qualitative trust modeling in SOA

Trust among cooperating agents is an essential precondition for every e-business transaction. It is becoming increasingly vital in service oriented architectures (SOAs), where services from various administration domains are deployed. Traditional hard security mechanisms with different techniques of authorization, access control and information security services give a solid foundation, but they fail when cooperating entities act deceitfully. Trust as a soft social security mechanism can protect against such threats and consequently improves the quality of services and reliability of service providers. This paper presents an abstract trust model that applies complementary qualitative methodology which addresses the core of trust as socio-cognitive phenomenon. The model complements existing quantitative methodologies and is applied in the web services environment that enables trust management in SOAs.

Clinical outcome of patients with coexistent antineutrophil cytoplasmic antibodies and antibodies against glomerular basement membrane.

Antineutrophil cytoplasmic antibodies (ANCA) and antibodies against glomerular basement membrane (anti‐GBM) rarely coexist. Both antibodies may be associated with rapidly progressive glomerulonephritis and pulmonary hemorrhage. We describe the clinical, serological and histological features of our patients with dual antibodies. From 1977 to 2008, 48 patients with anti‐GBM antibody‐associated renal disease were observed. Eight out of the 30 tested patients (26.7%), all females, had positive myeloperoxidase (MPO)‐ANCA coexistent with anti‐GBM antibodies. The patients mean age was 63.4u2003±u20037.8u2003years. Five presented with pulmonary‐renal syndrome, all but one were dialysis‐dependent on admission. They had constitutional symptoms and different organ involvement. The kidney biopsies revealed intense linear staining for immunoglobulin G and C3 along the glomerular and distal tubular basement membrane associated with irregular diffuse or focal extracapillary crescentic glomerulonephritis with necrosis of varying extent. Lesions of varying ages were characteristically expressed. Seven patients were treated with methylprednisolone and plasma exchange, four with cyclophosphamide, and one with intravenous immunoglobulin. After 28–74u2003months, there were three dialysis‐dependent survivors and one patient with stable chronic renal disease. Two clinical relapses with pulmonary involvement and MPO‐ANCA positivity without anti‐GBM antibodies occurred in two dialysis‐dependent patients. In summary, screening for ANCA and anti‐GBM antibodies should be undertaken in patients with clinical signs of systemic vasculitis. In dialysis‐dependent patients, the goal of treatment is to limit the damage of other involved organs and not to preserve renal function. Careful follow‐up is necessary due to the relapsing nature of the ANCA component of the disease.

Review of calciphylaxis and treatment of a severe case after kidney transplantation with iloprost in combination with hyperbaric oxygen and cultured autologous fibrin‐based skin substitutes

Abstract:u2002 Calciphylaxis, also known as calcific uremic arteriolopathy (CUA), is a rare complication in patients with end‐stage renal disease as well as in patients after renal transplantation. It should be suspected in patients with typical painful violaceous skin lesions on the extremities or on the trunk. Active multidisciplinary management approach, with intensive local wound care, is vital in these patients. Controlling parathyroid hormone, hyperbaric oxygenation, sodium thiosulphate, bisphosphonates, cinacalcet and skin grafting could be effective. In our report, we describe a case of CUA in a 43‐year‐old patient two years after kidney transplantation. Despite intensive standard treatment, his wounds progressed; therefore, we decided to use iloprost, in combination with hyperbaric oxygenation. The clean wounds were then covered with cultivated autologous skin cells to enhance wound epithelialization. Seven months after finishing iloprost and hyperbaric oxygen treatment and the first application of skin substitute, the wounds healed completely and remained healed during the four‐yr follow‐up period. We conclude that in patients with severe CUA‐induced wounds, the combined treatment with iloprost, hyperbaric oxygen and autologous cultured fibrin‐based skin substitutes can be effective. A combination of different treatment modalities is vital in patients with CUA.

Acute kidney injury in immunoglobulin A nephropathy: potential role of macroscopic hematuria and acute tubulointerstitial injury.

The aim of our retrospective study was to analyze the clinical course and outcome of patients with immunoglobulin A (IgA) nephropathy who presented with macroscopic hematuria and acute kidney injury (AKI). During the period from 1990 to 2005, seven out of 584 adult patients with IgA nephropathy (1.2%) fulfilled the criteria for macroscopic hematuria‐induced AKI. There was an equal gender distribution among our patients, and a rather high average age at presentation (55.7u2003±u200310.9u2003years). Four patients who were oliguric upon admission to hospital needed hemodialysis treatment. The average serum creatinine at the time of kidney biopsy was 429.8u2003±u2003377u2003µmol/L (median value 378). The percutaneous kidney needle biopsies showed focal proliferative crescentic glomerulonephritis of subclass III, according to the Haas scheme, associated with prominent red blood cell tubular casts and acute tubulointerstitial nephritis. Four patients with the most prominent crescents and tubulointerstitial involvement were treated with methylprednisolone. All patients, treated and untreated, recovered their kidney function (the serum creatinine at a median follow‐up of 15u2003months was 111.7u2003±u200338u2003µmol/L). In conclusion, AKI in IgA nephropathy accompanied by macroscopic hematuria appears to have been a reversible condition in our series of patients. Regarding pathogenesis, the kidney biopsy study points to the important role of glomerular bleeding with consequent, widespread obstructive red blood cell tubular casts accompanied by tubular injury and interstitial nephritis.

Influence of Renin‐Angiotensin‐Aldosterone System‐Blocking Drugs on Peritoneal Membrane in Peritoneal Dialysis Patients

Therapy with renin‐angiotensin‐aldosterone system (RAAS)‐blocking drugs prevents the development of fibrosis and angiogenesis in animal models and humans. In our study we have evaluated the systemic effect of RAAS blockade and the effect on peritoneal growth factors, cytokine production and membrane transport characteristics in patients on peritoneal dialysis. Thirty‐seven peritoneal dialysis (PD) patients were enrolled in our cross‐sectional study. Aldosterone and angiotensin II concentrations were measured in serum to determine the RAAS activity. The inflammatory and profibrotic activity was evaluated by measuring the concentration of C‐reactive protein (CRP), serum albumin, and peritoneal concentration of interleukin‐6 (IL‐6), vascular endothelial growth factor (VEGF), plasminogen activator inhibitor‐1 (PAI‐1), transforming growth factor‐β (TGF‐β) and cancer antigen‐125 (CA‐125). The transport characteristics of the peritoneal membrane were analyzed with a peritoneal equilibration test (PET). Results were compared between the group with RAAS‐blocking drugs (RAAS group) and the group without them (non‐RAAS group). Mean serum aldosterone concentration was significantly lower in patients treated with ARB‐blocking drugs (Pu2009=u20090.001) and serum angiotensin II concentration was lower in patients treated with ACE inhibitors (Pu2009=u20090.009). RAAS blockade resulted in lower peritoneal PAI‐1 levels (748.1 to 1222.7u2009ng/L; Pu2009=u20090.07) without any influence on CRP, peritoneal concentrations of IL‐6, VEGF, TGF‐β and CA‐125, or alteration in peritoneal membrane characteristics tested by PET. RAAS‐blocking drugs could be effective in preventing peritoneal fibrosis due to possible reduction of peritoneal PAI‐1 concentrations that have already been etiologically linked with fibrin deposition in the pathogenesis of encapsulating peritoneal sclerosis.

Formal apparatus for measurement of lightweight protocols

Lightweight protocols are an important topic in the area of computer communications. With the proliferation of security services not only ordinary communication protocols, but also cryptographic protocols, i.e. security services, have become a subject of research into possible appropriate lightweight solutions. At first glance it may seem surprising, but the evidence suggests that there is a permanent need for lightweight protocols. And this need is ever increasing, due to the gap between desktop (and other ordinary computing devices) and mobile wireless devices that have inherently limited resources. However, the notion of lightweight protocol has not been formally addressed in the literature, which is the purpose of this paper. A formal model that can be used to evaluate lightweight properties of protocols is presented and the appropriate metrics are introduced. Despite the fact that the model and the metrics target weak processing devices, they can be deployed for ordinary computing environments and may present a methodology for evaluation of lightweight cryptographic protocols in standardization processes.

Treatment of Antibody‐Mediated Rejection After Kidney Transplantation – 10 Years’ Experience With Apheresis at a Single Center

Antibody‐mediated rejection (AMR) is a major cause of kidney graft failure. We aimed to analyze treatment and outcome of AMR in a national cohort of 75 biopsy‐proven acute (43 patients, 57%) or chronic active (32 patients, 43%) AMR episodes between 2000 and 2015. The mean patients age was 46u2009±u200916u2009years, the majority was treated with plasma exchange, 4% received immunoadsorption and 7% received both. The majority received pulse methylprednisolone and low‐dose CMV hyperimmune globulin, 20% received bortezomib and 13% rituximab. Concomitant infection was treated in 40% of patients. The immediate treatment outcome was successful in 91%, the 1‐ and 3‐year graft survival rates were 71% and 57%, while 3‐year patient survival was 97%. Chronic active AMR was associated with worse graft survival than acute AMR (log rank Pu2009=u20090.06). To conclude, intensive treatment with apheresis and additional immunosuppression was effective in reversing AMR, but long‐term graft survival remains markedly decreased, especially in chronic active AMR.

Successful Treatment of Severe Hantavirus Nephritis With Corticosteroids: A Case Report and Literature Review

Hantaviruses can be associated with severe form of hemorrhagic fever with renal syndrome although there are only a few cases reporting chronic kidney disease after hantavirus infection. We report a severe nonresolving chronic renal failure after protracted Dobrava hantavirus infection successfully treated with corticosteroids. Ten days after working in a basement a 33‐year‐old man fell seriously ill, with high fever, chills, diffuse myalgia, headache and abdominal pain. After hospital admission a diagnosis of hemorrhagic fever with renal syndrome caused by Dobrava hantavirus was made. Acute oliguric kidney injury developed in the first 3 days after admission, in a few days diuresis restored and he became polyuric. Nevertheless renal failure persisted and he needed hemodialysis. Because of nonresolving kidney failure, nephrogenic diabetes insipidus and renoparenchymal arterial hypertension persisting 2 months after onset of symptoms, a kidney biopsy was performed, showing severe necrotizing tubulointerstitial nephritis. High dose methylprednisolone therapy was started and his renal function significantly improved. Two months later a second renal biopsy showed persisting elements of active necrotizing tubulointerstitial nephritis. We decided to stop corticosteroid treatment and introduced aldosterone antagonist eplerenon as anti‐fibrotic agent, and his renal function further improved and remained stable. Nine months later his serum creatinine concentration was 227u2009μmol/L, proteinuria 0.156u2009g/day and well controlled nephrogenic diabetes insipidus.

Encapsulating Peritoneal Sclerosis in Patients on Peritoneal Dialysis in Slovenia

Encapsulating peritoneal sclerosis (EPS) is a rare complication in patients on peritoneal dialysis (PD), the prevalence of which increases with the time spent on PD. Various causative factors have been proposed, but the pathogenesis still remains unclear. The aim of our retrospective study was to analyze the basic clinical characteristics and outcomes of five patients diagnosed with EPS out of 423 patients treated with PD between January 1983 and December 2003. One patient was admitted due to ultrafiltration failure of the peritoneal membrane, and four patients were admitted for acute peritonitis. All of our patients presented with clinical symptoms suggestive of obstructive ileus. We confirmed the diagnosis of EPS with a computer tomography scan, a diagnostic laparotomy or laparoscopy, and a biopsy of the parietal peritoneum. We treated all of our patients with catheter removal, transferal to hemodialysis, antibiotics, complete parenteral nutrition, methylprednisolone, and tamoxifen for 6u2003months. One patient was treated with surgical enterolysis and died of septic complications, another patient died of sudden cardiac death during treatment. Three patients were doing well for 4–7u2003months after the treatment was started. The incidence of EPS was 1.2% and the mortality rate was 40%. EPS is a rare complication in longstanding PD patients in our institution. Despite treatment with hemodialysis, complete parenteral nutrition, steroids, tamoxifen and surgical intervention, the mortality rate is high and comparable to other reports.

Pulse Wave Velocity and Augmentation Index in Renal Transplant Recipients - 4.6 Years Follow Up

Introduction Chronic kidney disease (CKD) is a risk factor for cardiovascular diseases leading to rapid progression of arteriosclerosis. After renal transplantation some of the traditional and CKD-specific risk factors disappear, however, new risk factors emerge, such as metabolic effects of immunosuppression therapy and new onset diabetes mellitus (NODAT). Arterial properties can be evaluated by measuring pulse wave velocity (PWV) and augmentation index (AI). The aim of the study was to define the long-term impact of renal transplantation on arterial stiffness. Another goal of the study was to evaluate effects of diabetes mellitus on PWV and AI. Materials and Methods The study was conducted on renal graft recipients, who had successful kidney transplantation in the years between 2011 and 2013. PWV and AI were evaluated noninvasively by applanation tonometry using SphygmoCor™ (AtCor Medical Pty. Ltd., Sydney, Australia) immediately after transplantation and four to five years thereafter. Clinical and biochemical data were obtained from the hospitals database. Results and Discussion 44 graft recipients (17 women, 27 men, age 49.1±11.5 years) were included in the study. The average follow-up period between the first and the second measurement was 55.7±6.9 months. PWV did not change significantly during the follow-up period (9.1±1.8m/s vs. 8.7±1.8m/s; p=0.137). PWV in the group of non-diabetic patients decreased in the follow-up period by 0.62±1.23 m/s, while it increased for 0.43±2.1m/s in the group of diabetic patients. However, the difference between the two was not significant (p=0.057). At the second measurement the difference in PWV between diabetic and nondiabetic patients was significant (10.2±1.8 vs. 8.3±1.23m/s; p=0.02). Duration of smoking before transplantation correlated significantly with PWV (p=0.012). AI in the whole group increased significantly (from 18.3±10.3% to 25.9±9.4%; p<0.01), whereas a significant difference in AI between diabetic and nondiabetic patients was not found. Conclusion PWV of the whole group did not change significantly during the follow-up period, possibly due to stabilization of the process of arteriosclerosis after renal transplantation. In the subgroup of patients without diabetes we observed a trend of PWV reduction, whereas in the subgroup of patients with diabetes we observed the opposite. Diabetes mellitus and duration of smoking before transplantation are important risk factors for arteriosclerosis progression after renal transplantation.