Conditions d’emploi de l’approximation de l’état quasi-stationnaire : cas du réacteur dynamique parfaitement agité

On montre que l’emploi de l’approximation de l’état quasi-stationnaire, lors du calcul d’un réacteur dynamique parfaitement agité à partir d’un mécanisme réactionnel, est légitime pour une réaction non explosive et lorsque le temps de passage est supérieur à une valeur appelée « période d’induction ». On établit les conditions pour lesquelles une réaction devient explosive. On montre que la période d’induction est fonction de la précision de calcul demandée, de la vitesse des processus d’amorçage et des constantes de vitesse des processus de ramification et de terminaison du mécanisme

Kidney transplantation for active multiple myeloma or smoldering myeloma: a case – control study

International audienceBackground: The increased survival of patients with multiple myeloma (MM) raises the question of kidney transplantation (KT) in patients with end-stage renal disease (ESRD).Methods: We included 13 patients with MM or smoldering myeloma (SMM) and ESRD transplanted between 2007 and 2015, including 7 MM with cast nephropathy, 3 with MM-associated amyloid light chain amyloidosis or light chain deposition disease and 3 SMM and compared them with 65 control-matched kidney-transplanted patients. Nine of the MM patients with KT were also compared with 63 matched MM patients on haemodialysis.Results: Pre-transplantation parameters were comparable, except for the duration of renal replacement therapy (57.8 versus 37.0 months; P = 0.029) in MM versus control patients, respectively. The median follow-up post-KT was 44.4 versus 36.4 months (P = 0.40). The median MM graft and patient survival were 80.1 and 117.2 months, respectively, and were not significantly different from control patients, although mortality tended to be higher in the 10 symptomatic MM patients (P = 0.059). MM patients had significantly more viral and fungal infections and immunosuppressive maintenance therapy modifications while they received lower induction therapy. Two MM patients relapsed and two SMM cases evolved to MM after KT. Three cast nephropathies occurred, two of them leading to ESRD. Moreover, survival of MM with KT increased relative to control haemodialysed patients (P = 0.002).Conclusions: Selected MM patients may benefit from KT but need careful surveillance in the case of KT complications and MM evolution

Plasma cell neoplasia after kidney transplantation: French cohort series and review of the literature

<div><p>Although post-transplant lymphoproliferative disorder (PTLD) is the second most common type of cancer in kidney transplantation (KT), plasma cell neoplasia (PCN) occurs only rarely after KT, and little is known about its characteristics and evolution. We included twenty-two cases of post-transplant PCN occurring between 1991 and 2013. These included 12 symptomatic multiple myeloma, eight indolent myeloma and two plasmacytomas. The median age at diagnosis was 56.5 years and the median onset after transplantation was 66.7 months (2–252). Four of the eight indolent myelomas evolved into symptomatic myeloma after a median time of 33 months (6–72). PCN-related kidney graft dysfunction was observed in nine patients, including six cast nephropathies, two light chain deposition disease and one amyloidosis. Serum creatinine was higher at the time of PCN diagnosis than before, increasing from 135.7 (±71.6) to 195.9 (±123.7) μmol/l (p = 0.008). Following transplantation, the annual rate of bacterial infections was significantly higher after the diagnosis of PCN, increasing from 0.16 (±0.37) to 1.09 (±1.30) (p = 0.0005). No difference was found regarding viral infections before and after PCN. Acute rejection risk was decreased after the diagnosis of PCN (36% before versus 0% after, p = 0.004), suggesting a decreased allogeneic response. Thirteen patients (59%) died, including twelve directly related to the hematologic disease. Median graft and patient survival was 31.7 and 49.4 months, respectively. PCN after KT occurs in younger patients compared to the general population, shares the same clinical characteristics, but is associated with frequent bacterial infections and relapses of the hematologic disease that severely impact the survival of grafts and patients.</p></div

Characteristics of plasma-cell neoplasias after kidney transplantation.

<p>Characteristics of plasma-cell neoplasias after kidney transplantation.</p

Time to onset of plasma cell neoplasia after kidney transplantation.

<p>Time to onset of plasma cell neoplasia after kidney transplantation.</p

Bacterial infections before and after the diagnosis of plasma-cell neoplasia after kidney transplantation.

<p><b>A:</b> The annual rate of bacterial infections was compared for each patient before and after the diagnosis of PCN during the kidney transplantation period. (*** = p<0.001). <b>B:</b> Type (x axis) and number (y axis) of bacterial infections during the follow-up of PCN. PCN: plasma cell neoplasia.</p

Evolution of serum creatinine after kidney transplantation, combined with the occurrence of asymptomatic or symptomatic PCN, hemodialysis and death for each patient.

<p>Evolution of serum creatinine (μmol/l) over time (in years) after kidney transplantation, for each patient. Patients were classified in six groups, and approximate time of diagnosis of SMM (smoldering multiple myeloma), symptomatic PCN (plasma-cell neoplasia), hemodialysis and death were added. MM: Multiple Myeloma. MGRS: Monoclonal Gammapathy of Renal Significance. LCDD: Light Chain Deposition Disease.</p

Intravenous Immunoglobulins Improve Survival in Monoclonal Gammopathy-Associated Systemic Capillary-Leak Syndrome

International audienceBackground: Monoclonal gammopathy-associated systemic capillary-leak syndrome, also known as Clarkson disease, is a rare condition characterized by recurrent life-threatening episodes of capillary hyperpermeability in the context of a monoclonal gammopathy. This study was conducted to better describe the clinical characteristics, natural history, and long-term outcome of monoclonal gammopathy-associated systemic capillary-leak syndrome.Methods: We conducted a cohort analysis of all patients included in the European Clarkson disease (EurêClark) registry between January 1997 and March 2016. From diagnosis to last follow-up, studied outcomes (eg, the frequency and severity of attacks, death, and evolution toward multiple myeloma) and the type of preventive treatments administered were monitored every 6 months.Results: Sixty-nine patients (M/F sex ratio 1:1; mean ± SD age at disease onset 52 ± 12 years) were included in the study. All patients had monoclonal gammopathy of immunoglobulin G type, with kappa light chains in 47 (68%). Median (interquartile range) follow-up duration was 5.1 (2.5-9.7) years. Twenty-four patients (35%) died after 3.3 (0.9-8) years. Fifty-seven (86%) patients received at least one preventive treatment, including intravenous immunoglobulins (IVIg) n = 48 (73.8%), theophylline n = 22 (33.8%), terbutaline n = 22 (33.8%), and thalidomide n = 5 (7.7%). In the 65 patients with follow-up, 5- and 10-year survival rates were 78% (n = 35) and 69% (n = 17), respectively. Multivariate analysis found preventive treatment with IVIg (hazard ratio 0.27; 95% confidence interval, 0.10-0.70; P = .007) and terbutaline (hazard ratio 0.35; 95% confidence interval, 0.13-0.96; P = .041) to be independent predictors of mortality.Conclusions: We describe the largest cohort to date of patients with well-defined monoclonal gammopathy-associated systemic capillary-leak syndrome. Preventive treatment with IVIg was the strongest factor associated with survival, suggesting the use of IVIg as the first line in prevention therapy