Cationic ruthenium allenylidene complexes as catalysts for ring closing olefin metathesis

A series of well accessible cationic ruthenium allenylidene complexes of the general type [(eta6-arene)(R3P)RuCl(=C=CR'2)]+ X- is described which constitute a new class of pre-catalysts for ring closing olefin metathesis reactions (RCM) and provide an unprecedented example for the involvement of metal allenylidenes in catalysis. They effect the cyclization of various functionalized dienes and enynes with good to excellent yields and show a great tolerance towards an array of functional groups. Systematic variations of their basic structural motif have provided insights into the essential parameters responsible for catalytic activity which can be enhanced further by addition of Lewis or Bronsted acids, by irradiation with UV light, or by the adequate choice of the "non-coordinating" counterion X-. The latter turned out to play a particularly important role in determining the rate and selectivity of the reaction. A similarly pronounced influence is exerted by remote substituents on the allenylidene residue which indicates that this ligand (or a ligand derived thereof) may remain attached to the metal throughout the catalytic process. X-ray crystal structures of the catalytically active allenylidene complexes 3b.PF6 and 15.OTf as well as of the chelate complex 10 required for the preparation of the latter catalyst are reported.

Efficacy of a new collection procedure for preventing bacterial contamination of whole-blood donations

BACKGROUND

Transfusion-related bacterial contamination is a serious problem. The introduction of bacteria into donations at the collection stage seems frequent, despite well-conducted phlebotomy site preparation. Additional preventive measures are required.

STUDY DESIGN AND METHODS

The aim of this study was to assess the potential efficacy of excluding the first 15 mL of blood to reduce the bacterial contamination of donations. A special device allowed the aseptic collection of two samples at the beginning of donation: S1 (first 15 mL) and S2 (next 15 mL). Bacteriologic cultures of S1 and S2 were performed by using an automated system. The procedure's efficacy was measured by the proportion of positive donations in S1 that were then negative in S2.

RESULTS

S1 and/or S2 were positive in 76 (2.2%) of 3385 donations. In about three-fourths of the culture-positive donations, contamination was detected in the first 15-mL sample only. Gram-positive cocci accounted for 81 percent of species, gram-positive bacilli for 14 percent, and gram-negative bacilli for 5 percent. The new procedure would have prevented the introduction of bacteria in 55 donations, reducing to 0.6 percent the risk of contamination from the first 15 mL collected.

CONCLUSION

Although the final effect on blood component bacterial contamination rates cannot be derived from the study, excluding the first 15 mL of blood may reduce the rate of bacterial contamination in donations.

Circulating DNA:anti-DNA complexes in systemic lupus erythematosus. Detection and characterization by ultracentrifugation

Although it is generally accepted that DNA:anti-DNA immune complexes play a significant role in the pathogenesis of tissue injury in systemic lupus erythematosus, their presence in the circulation is still a matter of controversy. In this study, we detected DNA:anti-DNA compexes by identification of both the antigen and(or) the antibody, the necessary requisites for immune complex definition, in 14 of 24 plasmas (7 of 11 patients). These antibodies were specific for native DNA and could be adsorbed by anti-immunoglobulin (Ig)G antisera. The DNA recovered was, at least in part, of low molecular weight. The presence of DNA:anti-DNA compexes was not related to high molecular weight IgG, cryoprecipitins, positive polyethylene glycol precipitation, or low plasma C3 levels. It was related significantly to low plasma C4 levels and to the presence of diffuse proliferative nephritis. The lack of correlation with other methods of detection of immune complexes and with the presence of heavy IgG (above 13 S) is in favor of the existence of other antigen-antibody systems (or aggregated immunoglobulins) in systemic lupus erythematosus plasmas. From the results, it appears that methods directed towards the demonstration of specific immune complexes are more informative than those detecting heavy or altered immunoglobulins.

Synthesis and catalytic applications of palladium N-heterocyclic carbene complexes as efficient pre-catalysts for Suzuki–Miyaura and Sonogashira coupling reactions

A new palladium complex series with N-heterocyclic carbene (NHC), pyridine and phosphine ligands, PdCl₂(L)NHC (2a–c)(L = NHC), PdCl₂(L¹)NHC(3a–c)(L¹ = pyridine), PdCl₂(L²)NHC(4a–c)(L² = triphenylphosphine) was synthesised and fully characterized.

Is adult idiopathic nephrotic syndrome food allergy? Value of oligoantigenic diets

To evaluate the prevalence of food hypersensitivity in idiopathic nephrotic syndrome (INS), an oligoantigenic diet was given for 10 days to 13 patients with INS who had not steadily responded to corticosteroids; 5 of these patients were corticodependent, 3 were corticoresistant and 5 had multiple relapses. A history of allergy was present in 8 cases and an increase in total serum IgE levels in 6. Sensitivity to food antigens was documented by skin tests in 5, by the radioallergosarbent test (RAST) in 5 and by the human basophil degranulation test (HBDT) in 11. At the end of the oligoantigenic diet, proteinuria was significantly reduced in the 13 patients as compared to the initial level. It decreased by more than 50% in 9 patients and disappeared completely in 5. It seems that an oligoantigenic diet is helpful in cases of INS that do not respond to corticosteroids. This argues for a role of food hypersensitivity in this disease and suggests that avoidance of specific foods on the longer term may be of benefit. This diet must be tried in INS before the initiation of immunosuppressive therapy.

Multivariate analysis of determinants of bacterial contamination of whole-blood donations

BACKGROUND AND OBJECTIVES

Introduction of bacteria into blood components at the collection stage seems to be a frequent occurrence. We therefore assessed determinants of bacterial contamination of whole-blood donations to gain insight into contamination mechanisms and direct prevention.

MATERIALS AND METHODS

A cross-sectional study was carried out on donors accepted for whole-blood donation in four French blood banks. Each blood bank used its own two-stage procedure for phlebotomy site preparation. Contamination was identified by culturing two 15-ml samples (collected aseptically at the outset of donation) in a BacT/Alert 240 system. Determinants were assessed by logistic regression analysis.

RESULTS

Bacterial contamination, mainly by skin flora, occurred in 76 (2.2%) out of 3385 donations. Significant determinants were as follows: the blood bank (odds ratio [OR] range = 3.0-5.6, P < 0.001); lack of repetition of scrub (OR = 2.7, P = 0.032); and donor age > 35 years (OR = 1.8, P = 0.036).

CONCLUSION

Systematic scrub repetition should be implemented to reduce bacterial contamination by skin flora at the collection stage. Further research is required to clarify the role of different antiseptic agents and of donor age.

Influence of lipid environment on insulin binding in cultured hepatoma cells

The influence of alterations of plasma membrane physico-chemical properties on insulin binding have been characterized in an insulin-sensitive rat hepatoma cell line adapted to grow for several generations in culture medium enriched with linoleic acid (18:2) or with 25-hydroxycholesterol. The cells took up 18:2 and 25-hydroxycholesterol added to the culture medium, without exhibiting any sign of intolerance or intoxication. These compounds respectively increased and decreased membrane fluidity at 37 degrees C. The cells demonstrated extensive changes in insulin binding parameters in response to experimental modifications of their membrane lipid composition. When determined at 4 degrees C, insulin receptors were present in the control cells at 136,000 sites/cell but this fell to 111,000 (P less than 0.05) in cells enriched in 18:2, and rose to 176,000 (P less than 0.001) in hydroxysterol-grown cells. According to a two-site model, the main effect of 18:2 was a significant increase of the number of high-affinity sites with a concomitant decrease of low-affinity sites. The hydroxysterol had the opposite effects on these parameters. The high-affinity insulin binding capacity of the hepatoma cells was affected by lipid supplementation in a similar way, whether it was determined at 4 degrees C or at 37 degrees C. Assuming a negative cooperativity model, 18:2 enhanced the degree of negative cooperativity among the sites, while 25-hydroxycholesterol reduced it. The time-course of insulin-induced receptor down-regulation was accelerated in the cells enriched in polyunsaturated fatty acids, but reduced in cells exposed to 25-hydroxycholesterol. These insulin-binding alterations cannot be directly related to modifications of cellular growth rate, receptor internalization or membrane fluidity per se, and are discussed as being more likely due to membrane lipid composition than to overall cell metabolism modifications.

An increase in circulating IgA antibodies to gliadin in IgA mesangial glomerulonephritis

In IgA glomerulonephritis (GN), the pathogenic role of IgA is well documented, but the specificity of these IgA is unknown. Cases of celiac disease associated with IgA GN have been reported and led us to investigate the role of gliadin sensitivity. We measured IgA, IgG and IgM antibodies to gliadin, beta-lactoglobulin and ovalbumin by ELISA (results expressed as optical density; OD) in 27 patients with primary IgA GN, 14 with membranous GN (MGN), 21 with idiopathic nephrotic syndrome (INS) and 21 healthy controls. The normal value for antigliadin IgA was less than 0.650 OD. 19/27 patients with IgA GN had a raised level versus 2/14 in MGN and 2/21 INS (p less than 0.001: IgA GN vs. MGN, INS and controls). Antibodies to beta-lactoglobulin were rarely found and were not more frequent in IgA GN. Cross-reactivity with reticulin was investigated in 16 patients who were serum-positive for IgA antigliadin: no reticulin antibodies were detected by immunofluorescence. Antigliadin IgA are of diagnostic value for distinguishing IgA GN from other GN, with a sensitivity of 70%, a specificity of 89%, a positive predictive value of 83% and a negative one of 79%.

Modifications of cellular lipids induce insulin resistance in cultured hepatoma cells

We altered the cellular lipid composition of an insulin sensitive rat hepatoma cell line through supplementation of the culture medium with linoleic acid (18:2) or 25-hydroxycholesterol, and we studied the effects on insulin stimulation of aminoacid transport system A and glycogen synthesis. The basal rate of sodium-dependent aminoisobutyric acid uptake was slightly reduced in hydroxysterol-treated cells and increased in 18:2-enriched cells. Maximal insulin stimulation of transport was decreased by about 40% in both 18:2 and 25-hydroxycholesterol modified cells, as compared to control cells. In addition to reduced responsiveness, the hydroxysterol-treated cells also showed a diminished sensitivity to insulin, as revealed by a right-shift of the dose-response curve leading to a ED50 of 1.2 X 10(-8) M (P less than 0.02), as compared to 2.45 X 10(-9) M in control cells and 2.13 X 10(-9) M in 18:2 enriched cells. Concerning glycogen synthesis, the basal rate was unaffected by 25-hydroxycholesterol supplementation and slightly reduced in cells enriched in 18:2. Maximal insulin stimulation of glycogen synthesis was reduced by about 40% in both types of lipid modified cells. 25-Hydroxycholesterol again provoked a decrease in sensitivity to insulin: the ED50 was enhanced to 4.9 X 10(-9) M (P less than 0.05), as compared to 1.25 X 10(-9) M in control cells and 1.57 X 10(-9) M in 18:2-supplemented cells. Taken together with the previously reported changes of insulin binding to lipid modified hepatoma cells (Bruneau et al. (1987) Biochim. Biophys. Acta 928, 287-296) our results demonstrate an influence of alterations of the cellular lipid composition on both binding and biological actions of insulin, leading to an insulin-resistant state. Divergences between insulin binding and action were obtained and it was suggested that post-binding events may be responsible for the observed changes. Our findings may be relevant to experimental and clinical states of insulin resistance.

Shiitake dermatitis recorded by French Poison Control Centers - new case series with clinical observations

CONTEXT

Shiitake (Lentinula edodes) is an edible mushroom which was initially grown in Japan and China and is now sold on the European market. Flagellate erythema may arise following shiitake consumption and was first described in Japan in 1974.

OBJECTIVE

This paper reports a French shiitake dermatitis case series.

METHODS

The findings of retrospective study of shiitake dermatitis cases, reported to French Poison Control Centres (PCC) from January 2000 to December 2013, are reported.

RESULTS

Among 32 exposed patients, 15 presented flagellate urticarial lesions after raw shiitake consumption. The first case of this series was reported in 2006 and the last nine cases were reported as of 2012. After shared meals, no symptoms were reported among guests, who preferred cooked shiitake to the raw mushroom. In this series, rashes appeared 12 h to 5 days (median: 24 h) after raw shiitake ingestion. Linear and itchy urticarial lesions formed on the trunk, arms, and legs within a few hours and persisted for 3-21 days. In four cases, rash and pruritus were either triggered or worsened by sun exposure. Eleven patients received corticosteroids, antihistamines, or both. All patients completely recovered.

CONCLUSION

Due to the rapidly increasing consumption of exotic food in Western countries, it is no surprise that cases of shiitake dermatitis are now appearing in Europe. The mechanism of shiitake dermatitis is thought to be toxic and due to lentinan, a polysaccharide component of the mushroom. There is no specific validated treatment for shiitake dermatitis. Health professionals and the general population should be aware of both the risk associated with raw shiitake consumption and of the good prognosis of this very spectacular and uncomfortable toxic dermatitis.

Phosphine-pyridonate ligands containing octahedral ruthenium complexes: access to esters and formic acid

Selective formation of esters from primary alcohols or formic acid from carbon dioxide was achieved in the presence of phosphine-pyridone containing ruthenium catalysts.

A new dicoumarinyl ether and two rare furocoumarins from Ruta montana

A new dicoumarinyl ether, rutamontine and two rare furocoumarins, heraclenol and isopimpinellin, were isolated from Ruta montana. The structure of rutamontine as 6-hydroxy-7-methoxy-3,7'-dicoumarinylether was determined by spectroscopic methods.

Induction, by adriamycin and mitomycin C, of modifications in lipid composition, size distribution, membrane fluidity and permeability of cultured RDM4 lymphoma cells

Adriamycin and mitomycin C were previously found to modulate the sensitivity of lymphoma cells to lysis by certain effectors of immunity and this modulation was dependent on drug concentration. In the present studies, RDM4 lymphoma cells were treated with different concentrations of the two drugs for 24 h in culture. These treatments resulted in changes in the lipid composition, membrane fluidity, cell size distribution, and permeability to 51CrO4, Trypan blue, Acridine orange and trimethylaminodiphenylhexatriene (TMA-DPH) of the cells. Changes in some of these parameters, as a function of drug concentration, resulted in dose-response curves which were bell-like shaped, hence paradoxical similarities between non-drug-treated cells and cells treated with higher drug concentrations were observed.

Ruthenium(ii) and iridium(iii) complexes featuring NHC–sulfonate chelate

Three new complexes bearing a chelating (κ²C,O) NHC-SO₃ ligand have been prepared.