[Acquired factor XI inhibitor and chronic lymphocytic leukemia]. / Allongement du TCA chez un patient atteint de leucémie lymphoïde chronique : à propos de la très rare découverte d'un autoanticorps antifacteur XI.

Autoimmune phenomena, most frequently autoimmune hemolytic anemia, is a well-known complication of lymphoproliferative diseases. We report a very rare association of a chronic lymphocytic leukemia with an acquired factor XI inhibitor. A 87-year-old man presented with auto-immune hemolytic anemia. He had untreated chronic lymphocytic leukemia for the past three years and renal insufficiency. Before surgical procedure for arteriovenous fistula, we discovered a very prolonged activated partial thromboplastin time (APTT), and an acquired factor XI inhibitor was detected. The patient was successfully treated with immunosuppressive therapy. Among patients with lymphoproliferative disorders the discovery of a prolonged APTT implies to search for rare autoimmune phenomena like acquired coagulation factor inhibitors.

Alteration in plasma antioxidant capacities in chronic renal failure and hemodialysis patients: a possible explanation for the increased cardiovascular risk in these patients.

OBJECTIVE: The high incidence of cardiovascular diseases in chronic renal failure (CRF) and hemodialyzed (HD) patients is now well established and the involvement of oxidative stress has been hypothesized in these phenomena. The aim of our study was to evaluate the level of oxidative stress in healthy controls (CTL) compared with CRF and HD patients before (pre-HD) and after (post-HD) the dialysis session, carried out on a high biocompatible polyacrylonitrile membrane AN69. METHODS: Several indicators of the extracellular redox status were evaluated in plasma. The ascorbyl free radical (AFR) was directly measured using electron spin resonance spectroscopy (ESR) and expressed with respect to the vitamin C level to obtain a direct index of oxidative stress. Indirect plasma parameters such as vitamin E, thiol and uric acid levels were also quantified. The plasma antioxidant status (PAS) was evaluated by the allophycocyanin test. Nitric oxide (NO) stable-end metabolites: nitrites and nitrates (NO(x)), were measured in plasma. RESULTS: In CRF patients, vitamin C and thiol levels were low, and the AFR/vitamin C ratio high compared with the CTL. On the other hand, PAS and uric acid levels were shown to be higher in CRF patients. After the dialysis session, vitamin C level decreased and AFR/vitamin C ratio increased. The thiol levels were shown to be increased, in return PAS and uric acid levels were significantly lower after the dialysis session. NO(x) levels rose during CRF, but were significantly decreased after the dialysis procedure. No differences in vitamin E status were observed between CTL, CRF and HD patients. CONCLUSION: Our study demonstrates that profound disturbances in the extracellular redox system occur during the course of chronic renal failure and hemodialysis, and may provide an explanation for the cardiovascular complications in these patients.

Biorthogonal filterbanks and energy preservation property in image compression.

The energy preservation property is among the most widely used properties of orthogonal transforms in image compression because the reconstruction error can be computed as the sum of the subband distortions. Thus, this is a key point in the use of efficient bit allocation techniques such as rate-distortion algorithms. Therefore, we study the nonorthogonality of biorthogonal filterbanks with reference to energy preservation from both theoretical and applicative points of view. We calculate the Riesz bounds as energy preservation bounds for filterbanks and discrete wavelet transforms, and then connect these results with the Riesz bounds of the related continuous wavelet transform. The simultaneous use of biorthogonal filterbanks and rate-distortion algorithms is then discussed as the issue of estimating the reconstruction error as an additive function of the subband distortion. We propose a weighted sum of the subband distortions as an estimate, whose accuracy is calculated by a wide range of experiments. This accuracy is shown to be correlated to the Riesz bounds of the filterbanks. We conclude that from this point of view, most of the usual biorthogonal filterbanks may be considered as nearly orthogonal.

[Diagnostic value of myocardial thallium stress scintigraphy in the detection of coronary artery disease in patients undergoing chronic hemodialysis]. / Valeur diagnostique de la scintigraphie myocardique au thallium sous stimulation dans la détection de la maladie coronarienne chez l'hémodialysé chronique.

Atherosclerotic heart disease is the leading cause of death in patients with end stage renal disease, but its non invasive detection remains difficult because of a low efficacy of exercise testing. The aim of the study was to evaluate diagnostic accuracy of thallium myocardial imaging after dipyridamole combined with exercise. Forty two chronic dialysis patients (34 men, 8 women) aged 55 +/- 11 years (range: 36 to 75) without symptom of angina nor myocardial infarction were studied. In each patient, an echocardiography, a myocardial scintigraphy with dipyridamole combined with symptom-limited exercise, and coronarography were performed. A coronary heart disease was diagnosed by coronarography in 10 patients (4.5 and 1 respectively with 1, 2 and 3 vessels diseased). Echocardiography detected a left ventricular hypertrophy (LVH) in 26 patients and a regional asynergia in 14 patients. A positive scintigraphy was present in 11 patients. Three false-positive and 2 false-negative on scintigraphy were noted. Sensibility, specificity, positive predictive value and negative predictive value were respectively evaluated at 80, 73, 73 and 93%. All the five patients with either false-positive or false-negative scintigraphy exhibited a LVH. CONCLUSION. In chronic dialysis patients, coronary heart disease may be detected by thallium myocardial imaging after dipyridamole combined with exercise.

[Focusing on peritoneal dialysis adequacy]. / Adéquation en dialyse péritonéale : mise au point.

The optimal method to assess the adequacy of peritoneal dialysis therapies is controversial. Today, the adequacy must not be considered as a number or a concept assessed only by two parameters (total KT/V urea and total solute clearance) but defined by many more items. In the absence of data, based on theoretical considerations, the reanalysis of the CANUSA study showed that renal kidney function, rather than peritoneal clearance, was associated with improved survival. Residual renal function is considered as a major predictor factor of cardiovascular mortality. Results of this reanalysis were supported by the adequacy data in ADEMEX, EAPOS and ANZDATA studies. Therefore, clinical assessment plays a major role in PD adequacy. The management of fluid balance, the regular monitoring of malnutrition, the control of mineral metabolism and particularly the glucose load, considered as the "corner-stone" of the system, are the main points to be considered in the adequacy of PD patients. The essential goal is to minimize glucose load by glucose-sparing strategies in order to reduce the neoangiogenesis of the peritoneal membrane.

[How to diagnose and treat peritoneal infections in patients with terminal chronic renal insufficiency treated by peritoneal dialysis]. / Comment diagnostiquer et traiter les infections péritonéales chez les malades en insuffisance rénale chronique terminale traités par dialyse péritonéale?

There have been improvements in the technique of peritoneal dialysis (PD) over the last ten years. However, peritoneal infections remain the major complication associated with this treatment, and the risk of infection cannot be accurately predicted. Nevertheless, it is widely accepted that simple connections should be replaced by improved systems of connection, and that patient training is important. Peritoneal infection should be suspected when the dialysate is turbid, whether or not associated with peritoneal irritation. None of the various techniques used for the culture of dialysates has been shown to be either more sensitive or more specific than any of the others. Thus, collaboration between the physicians supervising the dialysis and microbiologists is necessary to choose the culture techniques best adapted. The sensitivity should be at least 85 to 90%. If the sensitivity is lower, the techniques used should be reconsidered. There have been several hundred publications assessing treatments of peritoneal infections associated with PD. However, no particular antibiotic treatment has been demonstrated to be systematically superior. The use of associated antibiotics seems to be preferable initially, until the causative agent has been identified. For example, vancomycin with a third generation cephalosporin seems to be the association of choice, because of its efficacy, tolerance and ease of use. The optimal duration of treatment has not been established by randomised study, but 10 days is commonly used for Gram-positive infections, and longer for Gram-negative. Whatever the treatment used, the success rate should be at least 80 to 90%. Randomised trials with sufficiently large numbers of patients are required to determine the indications and delay before withdrawal of the DP catheter in cases of peritonitis which do not respond to antibiotics.

The management of uraemia in the elderly: treatment choices.

The particularity of geriatric medicine and the lack of information due to the fact that geriatric nephrology dates back only 10 years explains why the management of chronic uraemia among the elderly presents itself as a succession of difficult dilemmas. (1) Should causes of chronic renal failure be systematically determined and treated? Risk-benefit assessments of the investigations and treatments involved in preventing or slowing down the evolution to end-stage renal disease (ESRD) are required to answer this question. (2) In cases of ESRD, should dialysis always be considered? The fact that life expectancy is limited for the aged does not justify depriving them of treatment. Nevertheless, in some borderline situations, conservative treatment may be preferable. (3) When should dialysis be started? Currently the mortality before the 90th day of dialysis is very high among elderly patients. To improve results it is probably necessary to determine appropriate criteria for starting treatment before complications occur. (4) What is the best method for the first treatment? There is much controversy about the respective advantages of haemodialysis and peritoneal dialysis. The choice depends on the individual's medical and social conditions. (5) Should dialysis treatment be stopped, and, if so, in this case, when? The large acceptance rate of elderly patients for dialysis implies that withdrawal of treatment must sometimes be considered. Fears linked to this dilemma probably explain why some physicians choose to exclude elderly patients from dialysis. It seems to us more ethical to treat this group of patients and assume responsibility for stopping treatment should it be necessary.

Effects of long-term treatment with recombinant human erythropoietin on physiologic inhibitors of coagulation.

Recombinant human erythropoietin (rHu-EPO) in the treatment of renal anemia might predispose to an increased risk of thrombotic complications. In an attempt to comprehend the involvement of the physiologic inhibitors of coagulation in this process, we studied 2 groups of hemodialysis patients. Group I included 21 patients receiving a starting dose of 90 IU/kg/week s.c., and group II included 17 patients without rHu-EPO. The following coagulation tests were performed before rHu-EPO treatment, and after 1, 6 and 12 months: prothrombin time; activated partial fistula thromboplastin time; fibrinogen; plasminogen activity; antithrombin III activity; protein C activity; total and free protein S antigens, and C4b binding protein. Only the latter three parameters were changed in group 1, while high baseline levels of protein S antigens were found in both groups. A decrease in total and free protein S was observed within 1 month of treatment. At the 6th month total protein S returned to near pretreatment values, whereas a significant fall in free protein S (p = 0.007) was observed. All three parameters returned to near baseline values by 12 months. These results suggest that protein S activity can be altered at the beginning of EPO therapy, a change that under favoring circumstances might contribute to the thrombotic events reported during the early phase of rHu-EPO treatment.

Relationship between left ventricular hypertrophy, myocardial contractility, and load conditions in hemodialysis patients: an echocardiographic study.

Left ventricular hypertrophy (LVH) is common and is an independent cardiac risk factor in dialysis patients. The aim of this study was to assess hemodynamic determinants of LVH and, more particularly, the relationship between left ventricular mass, myocardial contractility, and load conditions. Eighty dialysis patients aged 51 +/- 15 years were prospectively studied by echocardiography. LVH was detected in 62 patients (78%). Left ventricular mass was significantly correlated to both end-diastolic volume (r = 0.54; P < 0.001) and end-systolic stress/end-systolic volume, an index of contractility (r = -0.66; P < 0.001), but not to systolic blood pressure or end-systolic stress, both indexes of afterload. Thus, in dialysis patients, the degree of LVH is significantly correlated with the severity of both left ventricular dilatation and contractile myocardial failure, but not with left ventricular afterload.