Study of the significance of parameters and their interaction on assessing femoral fracture risk by quantitative statistical analysis.

Early assessment of hip fracture helps develop therapeutic and preventive mechanisms that may reduce the occurrence of hip fracture. An accurate assessment of hip fracture risk requires proper consideration of the loads, the physiological and morphological parameters, and the interactions between these parameters. Hence, this study aims at analyzing the significance of parameters and their interactions by conducting a quantitative statistical analysis. A multiple regression model was developed considering different loading directions during a sideways fall (angle [Formula: see text] and [Formula: see text] on the coronal and transverse planes, respectively), age, gender, patient weight, height, and femur morphology as independent parameters and Fracture Risk Index (FRI) as a dependent parameter. Strain-based criteria were used for the calculation of FRI with the maximum principal strain obtained from quantitative computed tomography-based finite element analysis. The statistical result shows that [Formula: see text] [Formula: see text], age [Formula: see text], true moment length [Formula: see text], gender [Formula: see text], FNA [Formula: see text], height [Formula: see text], and FSL [Formula: see text] significantly affect FRI where [Formula: see text] is the most influential parameter. The significance of two-level interaction [Formula: see text] and three-level interaction [Formula: see text] shows that the effect of parameters is dissimilar and depends on other parameters suggesting the variability of FRI from person to person.

A frequency-domain approach to improve ANNs generalization quality via proper initialization.

The ability to train a network without memorizing the input/output data, thereby allowing a good predictive performance when applied to unseen data, is paramount in ANN applications. In this paper, we propose a frequency-domain approach to evaluate the network initialization in terms of quality of training, i.e., generalization capabilities. As an alternative to the conventional time-domain methods, the proposed approach eliminates the approximate nature of network validation using an excess of unseen data. The benefits of the proposed approach are demonstrated using two numerical examples, where two trained networks performed similarly on the training and the validation data sets, yet they revealed a significant difference in prediction accuracy when tested using a different data set. This observation is of utmost importance in modeling applications requiring a high degree of accuracy. The efficiency of the proposed approach is further demonstrated on a real-world problem, where unlike other initialization methods, a more conclusive assessment of generalization is achieved. On the practical front, subtle methodological and implementational facets are addressed to ensure reproducibility and pinpoint the limitations of the proposed approach.

Association Between Thrombophilic Gene Mutations and the Risk of Vascular Access Thrombosis in Hemodialysis Patients.

The cause of thrombosis in hemodialysis vascular access is considered to be of a multifactorial nature, including stenosis of the venous or arterial connection. Therefore, identification of relevant thrombotic risk factors could lead to an improved antithrombotic therapy. This case control study was performed to evaluate the relationship between Factor V (G1691A and A4070G) and Factor II polymorphisms and vascular access thrombosis in hemodialysis patients. One hundred and twenty-one patients undergoing dialysis were selected as subjects. This sample was divided into two groups; a case group of 60 patients who had sustained one or more thrombotic events that resulted in vascular access failure and a control group of 61 patients, who never had a thrombotic occlusion of a functioning permanent dialysis access. Our data demonstrated a significantly increased risk of vascular access thrombosis in carriers of the mutant FV (G1691A and A4070G) polymorphisms (P < 0.05).Further studies on a large-scale population and other genetic variants will be needed to find candidate genes for vascular access thrombosis in hemodialysis patients.

Pre-emptive treatment of hepatitis B infection by lamivudine in two Tunisian renal transplant recipients.

Infection with hepatitis B virus has a major implication for transplant recipients due to the risk of reactivation under immunosuppression, progression to chronic liver disease, development of liver cirrhosis and hepatocellular carcinoma. We report two cases of renal transplantation patients who were hepatitis B surface antigen positive before transplantation and were treated by Lamivudine.

Short- and long-term outcomes of kidney donors: a report from Tunisia.

Kidney transplantation remains the best treatment option of end-stage renal disease. Kidney donations are of particular interest with the currently increasing practice of living-donor transplantation. The purpose of this study was to analyze retrospectively the general health status as well as renal and cardiovascular consequences of living-related kidney donation. A total of 549 living-related kidney donors had donated their kidneys between 1986 and 2007. We attempted to contact all donors to determine short- and long-term outcome following kidney donation. All kidney donors who responded underwent detailed clinical and biochemical evaluation. The data were compared with age-matched health tables of the Tunisian general population. In all, 284 donors (52%) had a complete evaluation. They included 117 men and 167 women with a mean age of 42 ± 12 years. The major peri-operative complications that occurred in these donors included four cases of pneumothorax, six cases of surgical site infection, one case of phlebitis and one case of pulmonary embolism. None of the study cases died. The median length of hospital stay after donor nephrectomy was 6.5 days (range: 3-28 days). The median follow-up period was eight years. The mean creatinine clearance after donation was 90.4 ± 25 mL/min in men and 81.5 ± 27.2 mL/min in women. Proteinuria was >300 mg/24 h in 17 cases (5.9%). Fifty-eight (20.4%) donors became hypertensive and 19.6% of the men and 37.2% of the women became obese. Diabetes mellitus developed in 24 (8.4%), and was more common in patients who had significant weight gain. Our study suggests that kidney donors have minimal adverse effects on overall health status. Regular follow-up identifies at-risk populations and potentially modifiable factors. Creation of a national registry of living donors and their monitoring are an absolute necessity.

Thrombophilic disorders: a real threat to patients with end-stage renal disease on hemodialysis and at the time of renal transplantation.

Management of end-stage renal disease is the mainstay of prevention of renal vascular complications and kidney rejection. We sought to describe the association of some disorders such as diabetic nephropathy, polycystic renal disease, hypertension, and thrombophilia with renal failure and discuss possible mechanisms explaining the implication of the thrombophilic states in kidney allograft thrombosis and renal rejection. Five hundred and sixty-eight patients were included in this case-control study and multivariate analysis was applied. Cases and controls were tested for all major types of thrombophilia. Diabetic nephropathy, autosomal dominant polycystic kidney disease, hypertension, and smoking are the strongest causal agents of end-stage renal disease in Tunisia. It should also be noted that the prevalence of factor V Leiden (P = 0.05) and protein C deficiency (P = 0.005) were significantly higher in ESRD patients awaiting renal transplantation than controls. The present study has raised the possibility that thrombophilic factors may play a pathophysiological role in renal failure. These results will serve as a basis for anticoagulant prophylaxis aimed at preventing kidney rejection and renal allograft thrombosis.

Comparative study of perdialytic volemia variability in chronic dialysis patients between acetate- free biofiltration and bicarbonate hemodialysis.

We have developed since 1994 a new hemodialysis (HD) technique called acetate biofiltration 84% (AFB 84%) that is characterized by the absence of acetate in the dialysate and the complete correction of buffer balance by post- dilutional infusion of bicarbonate- based replacement solution. Our study aimed to compare the variability of perdialytic volemia [net ultrafiltration (UF) rate, total UF, Δweight (T4- T0)] during AFB 84% and bicarbonate dialysis (BD) for stable chronic hemodynamic patients. This was a prospective crossover study carried out on 14 patients for a total of 168 HD sessions (84 AFB 84% and 84 BD). Optical measurement of hemoglobin (Hb) concentration was incorporated into the dialysis monitor to allow the study of the relative blood volume. For both techniques, Hb measured by Hemoscan® correlated well with the laboratory measurements. Moreover, the comparison of the averages of the different indicators of the perdialytic volemia did not disclose any significant statistical differences. Nevertheless, the comparison of the variability of perdialytic volemia between both techniques showed less Δ volemia (T4- T0) during the AFB 84% than the BD (- 7.909% for BD and - 6.960% for ABF 84%, P = 0.0036). We conclude that the absence of acetate and maintaining an optimal osmolarity at the origin of a better plasma refilling rate are key factors that make AFB 84% a technique assuring a better perdialyitic hemodynamic tolerance in comparison with BD in chronic HD patients.

Role of thrombophilia in vascular access thrombosis among chronic hemodialysis patients in Tunisia.

Vascular access thrombosis represents a serious and common problem in hemodialysis patients. Therefore, identification of relevant thrombotic risk factors could lead to an improved antithrombotic therapy. This case control study was performed to evaluate the relationship between some thrombophilias and vascular access thrombosis in hemodialysis patients. Seventy-eight patients undergoing dialysis (between May 2007 and September 2009) were selected as subjects. This sample was divided into two groups; a case group of 28 patients who had sustained one or more thrombotic events that resulted in vascular access failure and a control group of 50 patients, who had never had a thrombotic occlusion of a functioning permanent dialysis access. Antithrombin, protein C and protein S levels were measured. Also, both groups were tested for the factor V Leiden mutation, the prothrombin G20210A mutation, the methylene tetrahydrofolate reductase C677T and A1298C mutations. Among genetic mutations of factor V Leiden, prothrombin G20210A and methylene tetrahydrofolate reductase genes, the C677T methylene tetrahydrofolate reductase mutation was the only significant genetic cause of vascular access thrombosis (P=0.005). Our data demonstrated a significantly increased risk of vascular access thrombosis in carriers of the C677T methylene tetrahydrofolate reductase mutation.

[Acetate-free hemodialysis: what does it mean?]. / Hémodialyse sans acétate: qu'est-ce vraiment?

Substituting bicarbonate by acetate in dialysis fluids has been proposed for avoiding precipitation of calcium and magnesium carbonates. However, acetate hemodialysis has been abandoned because of deleterious effects of acetate. Conventional bicarbonate hemodialysis is not totally acetate-free, because 3 to 7 mEq/l of acetic acid are added to the dialysate. Acetate-free hemodialysis is possible with another acid (chlorhydric acid or citric acid) or without acid by using some techniques of low-efficiency hemodiafiltration, as acetate-free biofiltration, which avoids the deleterious effect of blood acidification into the dialyzer. In this paper, advantages and disadvantages of different techniques of acetate-free hemodialysis are discussed.

Visceral leishmaniasis in a renal transplant recipient treated with allopurinol.

Leishmaniasis is an infection caused by a protozoan parasite belonging to the genus Leishmania and transmitted by the Phlebotomus sandfly. We report a case of visceral leishmaniasis in a 49-year-old male renal transplant recipient, a resident of the western part of Tunisia, which is an endemic zone for the disease. Just before and after the transplantation, the patient resided in Tunis, which is non-endemic for leishmaniasis. Visceral leishmaniasis occurred eight years after renal transplantation, and the clinical picture was characterized by fever and pancytopenia. Leishmaniae were detected by bone marrow aspiration. Pentavalent antimonal was used for 28 days and was substituted by allopurinol (20 mg/kg per day). One year after the infection, the patient remains totally asymptomatic. Our report suggests that visceral leishmaniasis may complicate the clinical course of organ transplantation and can be fatal, particularly when untreated. Relapses may occur after completion of the apparently effective treatment. Allopurinol could be a solution to avoid these relapses.

Cancers after renal transplantation: multicenter experience.

Renal transplant recipients are at higher risk of certain tumors such as lymphomas and skin cancers and than the general and dialysis populations. We retrospectively studied the prevalence of tumors in adult renal transplant recipients in four Tunisian centers of transplantation in Tunis, Monsatir and Sfax from January 1986 to January 2005. The study included 36 patients; 19 men and 17 women with a mean age of 34.6 years (range from 18-54 years). The mean time since dialysis to transplantation was 43 months (6-131months). Maintenance therapy was based on calcineurin inhibitors (CNI) in 86 % of cases, on antimetabolites and corticosteroids in 100 % of cases. Anti-thymoglobulin was administered in a mean course of 12.4 days in 78 % of the patients. Acute rejection occurred in 25 cases and was treated with polyclonal or monoclonal antibodies on 40 % of cases. Incidence of cancer among our population was 7 % and occurred after a mean period of 54 months of transplantation (range from 4-160 months). Eighty three percent of the tumors were solid, and the rest were in the skin. Kaposi sarcoma formed 41.6 % and non-Hodgkin or Hodgkin lymphoma 27.7 % of the solid tumors, while spinocellular carcinoma formed 83% and basocellular carcinoma 17% of the skin tumors. Switching CNI to sirolimus in 8.3% cases was associated with a favorable outcome. Mortality was the outcome in 33.3% of the patients with cancer, while partial or complete regression of cancers was observed in 55.5% cases after decreasing the doses of the immunosuppressive medications. We conclude that post renal transplant cancer is mainly characterized by the predominance of Kaposi sarcoma favored by solar exposure and rigorously induced and maintained immunosuppression. Careful follow-up may results in early intervention and decrease mortality.

Variability of acid-base status in acetate-free biofiltration 84% versus bicarbonate dialysis.

The ultimate goal of hemodialysis (HD) treatment is to achieve the highest level of efficacy in the presence of maximal clinical tolerance. With an aim to offer good hemodynamic stability, as observed during the acetate-free biofiltration 14% (AFB 14%) to patients who are intolerant to bicarbonate dialysis (BD) and with less cost, we have developed since June 1994, a new HD technique, namely AFB 84%. This study was carried out to analyze acid-base variations during the AFB 84% in comparison to BD in hemodynamically stable patients on regular HD. This was a prospective randomized crossover study carried out on 12 patients (6 males and 6 females) for a total of 144 HD sessions (72 BD and 72 AFB 84%). Patients with decompensated cardiomyopathy, respiratory diseases or uncontrolled hypertension were not included in the trial. All the patients were treated with BD or AFB 84%; the latter is characterized by the absence of acetate in the dialysate and a complete correction of buffer balance by post-dilutional infusion of bicarbonate-based replacement solution. The comparison of pre-dialysis arterial acid-base and blood-gas parameters revealed no significant differences of pH, HCO(3)(-) and paCO(2) levels between the two techniques. Analysis of post-dialysis parameters showed that, among patients dialyzed with BD, there was over correction of metabolic acidosis with a tendency towards metabolic alkalosis. In contrast, in patients dialyzed with AFB 84%, we observed a significant improvement in pH and HCO(3)(-) levels but the increase in paCO(2) level was not significant. A comparison of these parameters between the two techniques showed statistically significant difference in pH, HCO(3)(-) and paCO(2) levels, but not for paO(2) level. AFB 84% can offer some important advantages with the complete absence of acetate from the substitution fluids, and permits a better correction of metabolic acidosis than BD, without causing alkalosis.

[Study of contents of nitrates, fluorides, aluminium in dialysis water in Tunisia]. / Etude des teneurs en nitrates, aluminium, et fluorures dans les eaux de dialyse en Tunisie.

Nitrates, fluorides and aluminum have often been incriminated in cases of poisoning sometimes life threatening such as methaemoglobinaemia, dental and skeletal fluorosis, and myoclonal encephalopathy in patients undergoing haemodialysis. The three elements mentioned have something in common: their water origin (drinking water and dialysis water). To study the situation in Tunisia in this respect we propose to determinate the contents of nitrates, fluorides, and aluminum in drinking water and dialysis water supplied by the water board (SONEDE). 540 samples of drinking water and dialysis water were taken from 95 centers of haemodialysis scattered all over the country, between January 2000 and December 2001. These samples are divided in three parts (drinking water, soften water, and dialysis water ). Results show levels of fluorides < 1.5 ppm in most areas with the exception of zones rich in phosphate where the mean level is 1.61 +/- 1.22. the levels of nitrates are in most regions < 50mg/l and those of aluminum < 100microg/l. The levels of fluorides, nitrates and aluminum in dialysis water were within acceptable national and international limits excepting a few centers where the levels of the these contaminants are high, exposing patients on haemodialysis to acute and chronic intoxication. This contamination is caused in majority of cases by a dysfunction of water dialysis treatment chain, therefore caution is necessary and strict measures of control should be introduced.

[Clinical evaluation of acetate-free biofiltration at 84 0/00 in patients with chronic renal insufficiency]. / Evaluation clinique a moyen terme de la technique de biofiltration sans acetate a 84 0/00 chez les malades insuffisants renaux chroniques.

We report in this study the outcome of chronically hemodialysed patients with a new technique: Acetate free biofiltration 84@1000. This study is divided into two steps: during the first period we studied the hemodynamic stability of the technique in patients hemodynamically unstable under bicarbonate hemodialysis. During the second period we compared the hemodynamic effects and the quality of dialysis in these patients with other patients under bicarbonate hemodialysis. We obtained less hypotensive episodes, a better correction of acidosis, a better tolerance of the technique and comfort of the patient with the new technique, the quality of dialysis was the same with both techniques. We recommend the use of acetate free biofiltration 84@1000 whenever the patients are hemodynamicallyunstable with bicarbonate hemodialysis.