Phytochelatin production by marine phytoplankton at low free metal ion concentrations: laboratory studies and field data from Massachusetts Bay.

Phytochelatins are small metal-binding polypeptides synthesized by algae in response to high metal concentrations. Using a very sensitive HPLC method, we have quantified phytochelatins from phytoplankton in laboratory cultures at environmentally relevant metal concentrations and in marine field samples. Intracellular concentrations of phytochelatin, in the diatom Thalassiosira weissflogii, exhibit a distinct dose-response relation with free Cd2+ concentration in the medium--not with total Cd(2+)--and are detectable even when the free Cd2+ concentration is less than 1 pM. In Massachusetts Bay, phytochelatin levels (normalized to chlorophyll a) in the particulate fraction are similar to those measured in laboratory cultures exposed to picomolar free Cd2+ concentrations and exhibit a decreasing seaward trend. Incubations of natural samples with added Cd2+ confirmed the induction of the peptides by this metal. Ambient phytochelatin concentrations thus appear to provide a measure of the metal stress resulting from the complex mixture of trace metals and chelators in natural waters.     

Synthesis and characterisation of novel nanospheres made from amphiphilic perfluoroalkylthio-beta-cyclodextrins.

This work describes the synthesis of new amphiphilic perfluorohexyl- and perfluorooctyl-propanethio-beta-cyclodextrins and the comparison of the ability of these molecules and alkyl analogue, nonanethio-beta-cyclodextrin to form nanospheres. Nanospheres were prepared using nanoprecipitation method (perfluoroalkylthio-beta-cyclodextrin in THF [0.11 x 10(-3)M], stirring rate 700rpm, addition of aqueous phase at 64 degrees C into organic phase at 50 degrees C). They were characterised by Photon Correlation Spectroscopy (PCS) and by electron microscopy (SEM and cryo-TEM). The nanospheres prepared from these new beta-cyclodextrin derivatives have an average size of 260nm, and appear to be spherical in cryo-TEM images. Whereas alkyl analogue forms polydisperse aggregates with sizes in the range 60-350nm.     

Examination of the role of the colloids hydroxyethylstarch, dextran, human albumin, and plasma proteins in a modified UW solution.

The delayed contralateral nephrectomy procedure (three-step) produced inconsistent results, indicating that the preserved autotransplanted kidney tends to remain unfunctional and to regenerate incompletely unless the demand for work is placed upon it. Omission of HES in UW (UW-plain) did not affect preservation success, but resulted in increased graft edema. Substitution of HES in UW with plasma (SGF-V) or albumin (MAlb) gave significantly worse results than UW-like solutions with or without synthetic colloids. Replacement of HES in UW with UMdex-70 or UMdex-500 gave nonsignificantly worse results than UW-like solutions with or without synthetic colloids. The use of UMdex-40 as the main colloid in UW cheapened the solution, equalled the preservation success of UW and UW-plain but surpassed UW-plain in edema prevention, and exceeded UW concerning recovery of graft microcirculation.     

Superoxide production by peripheral blood monocytes during sustained endotoxaemia in sheep.

1. We have studied the time course of the numbers of arterial monocytes and their superoxide anion (O2-) production in a chronically instrumented sheep model of subacute endotoxaemia induced by a continuous intravenous infusion of Escherichia coli lipopolysaccharide (20 ng min-1 kg-1). 2. Four out of 11 animals died from irreversible respiratory and cardiovascular failure within 21 h of the start of lipopolysaccharide administration ('non-survivors'), whereas in the seven surviving sheep ('survivors') there was a persistence of decreased systemic vascular resistance, systemic hypotension, pulmonary hypertension, anorexia and lethargy. 3. O2- generation by isolated monocytes was measured by the O2- dismutase-inhibitable reduction of ferricytochrome c after stimulation with phorbol myristate acetate (100 ng/ml) or opsonized zymosan (3 mg/ml). Basal mean value of phorbol myristate acetate-stimulated O2- production was significantly (P = 0.008) higher for non-survivors (31.3 +/- 8.8 nmol 30 min-1 10(-6) cells; n = 4) than for survivors (6.2 +/- 2.3 nmol 30 min-1 10(-6) cells; n = 7). 4. For both survivors and non-survivors, monocyte counts and phorbol myristate acetate-stimulated O2- production increased over time to reach in survivors a plateau after 2 days of continuous lipopolysaccharide infusion. Similar results were obtained when monocytes were stimulated for O2- production with opsonized zymosan. 5. These results suggest that (1) increased O2- production by monocytes and monocytosis appear with a precise, delayed time course during the development of subacute endotoxaemia in sheep; and (2) a high stimulated O2- production by monocytes before lipopolysaccharide administration may represent a predictive factor for the subsequent respiratory failure and outcome of endotoxaemia.     

La maladie de Sinding-Larsen et Johansson

The Sinding-Larsen and Johansson disease is a non-negligible cause of gonalgia among children of 10 to 14, often misinterpreted as « growing pain . The disease is a benign pathology of the lower pole of the patella which occurs preferentially in physically active children. Our study, carried out in conjunction with the medical department INSEP, is based on a literature review as well as an analysis of 14 cases over two years. The present work eventually led to the differentiation of four etiopathological categories accounting for all the radiochemical evolutions observed. At the origin of these four categories, two factors coexist: the local fragility (the presence of cartilage at the lower pole of the patella) and the trigerring factor, which is most often sports practice. This explains why among children practicing sports, even intensively, only few suffer from this disease.It is essential to know the different radiological aspects of the normal patella in children, in order not to misinterpret one of these aspects with the Sinding-Larsen and Johansson disease.Always benign, the Sinding-Larsen and Johansson disease can very seriously disturb the « careerof children, engaged in high-level sports activity, the average time of evolution being seven months.     

Association of donor TNFRSF6 (FAS) gene polymorphism with acute rejection in renal transplant patients: a case-control study.

BACKGROUND: Genetic factors other than HLA have been reported to be associated with the outcome of organ transplantations. Because binding of FasL to its receptor Fas could play an important role in tubulitis and in the death of graft tubular epithelial cells during kidney allograft rejection, a gene polymorphism recently identified in position -671 in the promoter of the TNFRSF6 gene coding for Fas was investigated in donors. METHODS: A case-control study was performed within a cohort of non-hyperimmunized adult patients who had received cadaveric kidney transplants based on the occurrence or absence of acute cellular rejection in the first 6 months after renal transplantation. Each recipient from the acute rejection group (n = 35) was matched for age (+/- 5 years) and number of HLA-DR mismatches with two recipients within the non-acute rejection group (n = 70). RESULTS: The TNFRSF6-GG genotype was more frequent in donors in the group without rejection episodes. In contrast, patients who received a kidney from a TNFRSF6-A carrier were more likely to experience acute rejection episodes (relative risk nearly 2.1). CONCLUSION: This study suggests that donor TNFRSF6 polymorphism directly or indirectly influences acute kidney rejection episodes.     

Bone mass and bone cellular variations after five months of physical training in rhesus monkeys: Histomorphometric study

Summary Five Rhesus Monkeys (Maccaca mulatta), a suitable nonhuman model, performed 5 months of ropeclimbing exercise. Duration of the training sessions was progressively increased to reach 1 hour/day after 1 month of training and was maintained until the end of the experiment. Bone mass parameters, bone resorption, and bone formation activity were measured by histomorphometric analysis on iliac crest bone biopsies before and after the experiment. Mineral apposition rate was measured in cortices and trabecular bone after double calcein labeling. Five months of rope-climbing exercise had determined a significant decrease of bone volume with a slight decrease of the number and thickness of trabeculae. This might induce an alteration of biomechanical properties of bone. These architectural modifications were associated with a nonsignificant decrease of bone resorption activity. But the main effect of training was an important decrease of bone formation activity without change of the mineral apposition rate. Endurance exercise at low intensity has determined a decreased bone turnover with osteoblastic depression. This animal experiment points out that exercise modalities might be important in the bone response to training and should be carefully defined for preventive use in humans.     

Pharmacokinetics of ceftazidime injected peritoneally in continuous ambulatory peritoneal dialysis

Peritonitis is the most frequent complication in patients under continuous ambulatory peritoneal dialysis. Intraperitoneal administration of ceftazidime in a dose of 125 mg per liter dialysate achieved serum concentrations higher than the minimal inhibitory concentrations of most organisms in spite of low peritoneal clearance. Serum concentration was stable up to the 120th hour. Dialysate osmolarity had no influence on serum concentration, peritoneal absorption or clearance of ceftazidime. Peritoneal inflammation did not cause changes in ceftazidime pharmacokinetics. Ceftazidime used alone as the first choice treatment was successful in 85%, of cases.