Immunosuppressive effects of<Emphasis Type="Italic"> Ixodes ricinus</Emphasis> tick saliva or salivary gland extracts on innate and acquired immune response of BALB/c mice

Saliva and salivary gland extract (SGE) of Ixodes ricinus ticks have suppressive effects on the innate immune response of BALB/c mice. Tick saliva prevents hemolysis of sheep red blood cells (SRBC) by the human alternative pathway of complement. The adaptive immune response is also modulated by tick antigens (saliva or SGE). When stimulated in vitro with increasing doses of tick antigens, the proliferation and IL-4 production of draining lymph node T cells of mice infested with nymphal ticks increase, peak and then decrease. These results indicate that immunostimulative and immunosuppressive molecules have competing effects in tick saliva or in SGE. I. ricinus saliva inhibits, in a dose-dependent manner, splenic T cell proliferation in response to concanavalin A (ConA). Tick SGE or saliva injected intraperitoneally to BALB/c mice simultaneously with SRBC systemically immunosuppress the anti-SRBC response as shown in vitro by the reduced responsiveness of sensitized splenic T cells to restimulation with SRBC. In brief some components of SGE or tick saliva reduce the responsiveness of draining lymph node T cells and of sensitized splenic T cells in vitro. The responsiveness of naive splenic T cells to ConA stimulation in vitro is also decreased by tick saliva. Modulation of host responses by tick antigens may facilitate tick feeding, transmission and the propagation of pathogens.     

Composition and dynamics of potentially toxic dinoflagellates in a shallow Mediterranean lagoon

The population dynamics of harmful microalgae was investigated in the semi-enclosed shallow lagoon, Tunis northern lagoon (South Mediterranean), during a 1-year period from January to December 2007. A total number of 16 potentially toxic dinoflagellates were identified. Density of each species was analyzed in time and space and in relation to environmental parameters. Some species such as Alexandrium catenella, A. pseudogonyaulax, A. tamarense, Dinophysis sacculus, Prorocentrum lima, P. minimum and Gonyaulax spinifera developed high cell concentrations, particularly during spring and summer seasons. Other species such as A. insuetum, A. lee, A. minutum, Coolia monotis, D. acuminata, D. caudata, D. fortii, Ostreopsis siamensis and P. concavum were detected in this coastal ecosystem, but they were rare or appeared in very low densities. Densities of the most abundant species were closely associated with spring and summer conditions, being positively correlated with water temperature and salinity. These species performed well in this lagoon, but the specific species-dependent affinity to each of the environment factors determined which organisms proliferated. The spatial distribution of the abundant species exhibited a marked increase towards the western and southern parts of the lagoon represented by sites C, D and E. Examination of the temporal distribution revealed that the species more prone to bloom are those with extensive spatial distribution and frequent presence throughout the year such as D. sacculus. Statistical analysis of D. sacculus density dynamics showed a significant difference between summer and winter assemblages. It presented a positive correlation with water temperature and salinity, but it seems to be tolerant to all levels of nutrients.     

Fate of Starr-Edwards prostheses in the mitral position. Prognostic factors. Apropos of 309 cases

The authors report the long-term results of 309 patients undergoing isolated mitral valve replacement with a 6120 Starr Edwards mitral valve prosthesis in the great majority of cases, mainly for rheumatic mitral valve disease, with predominant mitral regurgitation. The average age was 26 +/- 14 years with 25% of children. The operative mortality was 9% and late mortality after a mean follow-up period of 4 years was 13,5% mainly due to thromboembolic complications and to myocardial dysfunction. The long-term results with an average 45 month follow-up showed a 10 year survival rate of 70,6% with an excellent clinical result in 71% of cases and an acceptable result in 10%; 20% of patients were considered poor long-term results because of myocardial dysfunction and thromboembolic complications. Endocarditis and perivalvular leaks were rarely observed (9 cases). A study of preoperative parameters which could influence long-term results showed that the quality of long-term survival was significantly correlated to age, the duration of cardiac disease before surgery, cardiomegaly and the presence of preoperative cardiac failure and tricuspid regurgitation. The incidence of thromboembolism was 4,7% patient years and the frequency of these complications was not related to the quality of anti-vitamin-K therapy. Patients under effective anticoagulant therapy had the highest incidence of haemorrhage (10%). This study confirms that the Starr Edwards 6120 prosthesis is a satisfactory choice for mitral valve replacement considering its durability (no cases of abnormal wear) and the 70% ten year survival rate. The problem of myocardial dysfunction could be resolved by earlier surgery.(ABSTRACT TRUNCATED AT 250 WORDS)     

Insuffisance rénale aiguë révélatrice d’un lymphome rénal. À propos d’un cas

Acute renal failure, as the initial manifestation of lymphoma, has been reported only in a few cases. In this work, we report the case of a 28-year-old women admitted for acute renal failure. Her physical examination detected bilateral kidney enlargement. Laboratory evaluation revealed a serum creatinine value 218 μmol/l. A 24-hour urine collection analysis allowed the detection of 1 g of protein. No red cells were found after urinanalysis. Renal ultrasound showed massively enlarged kidneys. Renal biopsy of the kidney and pathologic examination showed diffuse infiltration of the interstitium with lymphocytes and atypical cells positive for CD20 markers. A diagnosis of diffuse large B-cell type non-Hodgkin lymphoma was made. However, investigations revealed the presence of two others sites of lymphoma: gastric and ophthalmic. The patient's renal function and kidney size as well as the other lymphoma locations were normalized after the initiation of chemotherapy.