Tracking of airborne radionuclides from the damaged Fukushima Dai-ichi nuclear reactors by European networks

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ((131)I) and cesium isotopes ((137)Cs and (134)Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous (131)I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous (131)I and the large underestimation of the total (131)I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous (131)I fraction to total (131)I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the (134)Cs to (137)Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total (131)I inventory that has passed over Europe during this period was <1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe.

Reaction of metformin with dicarbonyl compounds. Possible implication in the inhibition of advanced glycation end product formation

Dicarbonyl compounds such as methylglyoxal and glyoxal are extremely reactive glycating agents involved in the formation of advanced glycation end products (AGEs), which in turn are associated with diabetic vascular complications. Guanidino compounds such as aminoguanidine appear to inhibit AGE formation by reacting with alpha-dicarbonyl compounds. The aim of this work was to study whether the antihyperglycemic agent metformin (a guanidine-like compound) might react with reactive alpha-dicarbonyls. Metformin was incubated at pH 7.4 and 37 degrees in the presence of either methylglyoxal or glyoxal and reaction products analysed by HPLC coupled to mass tandem spectrometry. AGE formation on albumin by methylglyoxal and glyoxal in the presence or absence of metformin was also studied by measuring the fluorescence at 370/440 nm after albumin-AGE isolation by ultrafiltration. As a standard for mass spectra analysis, a metformin-methylglyoxal adduct was chemically synthesised and characterised as a triazepinone (2-amino-4-(dimethyl-amino)-7-methyl-5,7-dihydro-6H-[1,3,5]triazepin+ ++-6-one). The results obtained showed that metformin strongly reacted with methylglyoxal and glyoxal, forming original guanidine-dicarbonyl adducts. Reaction kinetic studies as well as mass fragmentation spectra of the reaction products were compatible with the presence of triazepinone derivatives. In the presence of metformin, AGE-related fluorescence after albumin incubation with either glyoxal or methylglyoxal was decreased by 37% and 45%, respectively. These results suggest that besides its known antihyperglycemic effect, metformin could also decrease AGE formation by reacting with alpha-dicarbonyl compounds. This is relevant to a potential clinical use of metformin in the prevention of diabetic complications by inhibition of carbonyl stress.

Involvement of arginine 120, glutamate 524, and tyrosine 355 in the binding of arachidonate and 2-phenylpropionic acid inhibitors to the cyclooxygenase active site of ovine prostaglandin endoperoxide H synthase-1

Examination of the crystal structure of the ovine prostaglandin endoperoxide synthase-1 (PGHS-1)/S- flurbiprofen complex (Picot, D., Loll, P.J., and Garavito, R.M. (1994) Nature 367, 243-2491) suggests (a) that the carboxyl group of arachidonic acid interacts with the arginino group of Arg120; (b) that Arg120 forms an important salt bridge with Glu524; and (c) that Tyr355, which is in close proximity to Arg120, could determine the stereochemical specificity of PGHS-1 toward 2-phenylpropionic acid inhibitors. To test these concepts, we used site-directed mutagenesis to prepare ovine PGHS-1 mutants having modifications of Arg120 (R120K, R120Q, R120E), Glu524 (E524D, E524Q, E524K), and Tyr355 (Y355F) and examined the properties of the mutant enzymes expressed in COS-1 cells. All of the mutants retained at least part of their cyclooxygenase and peroxidase activities except the R120E mutant, which had no detectable activity. The Km values of the R120K and R120Q mutants with arachidonic acid were 87 and 3300 microM, respectively, versus 4 microM for native PGHS-1. The R120Q mutant failed to undergo suicide inactivation during catalysis or time-dependent inhibition by flurbiprofen. These results are consistent with Arg120 binding the carboxylate group of arachidonate and suggest that interaction of the carboxylate group of substrates and inhibitors with Arg120 is necessary for suicide inactivation and time-dependent inhibition, respectively. The Km values for the E524D, E524Q, and E524K mutants were not significantly different from values obtained for the native PGHS-1, suggesting that this residue is not importantly involved in catalysis or substrate binding. The effect of modifications of Arg120 and Tyr355 on the stereospecificity of inhibitor binding was determined. Ratios of IC50 values for cyclooxygenase inhibition by D- and L-ibuprofen, a competitive cyclooxygenase inhibitor, were 32, 67, and 7.1 for native PGHS-1, R120Q PGHS-1, and Y355F PGHS-1, respectively. The decreased stereochemical specificity observed with the Y355F PGHS-1 mutant suggests that Tyr355 is a determinant of the stereospecificity of PGHS-1 toward inhibitors of the 2-phenylpropionic acid class.

Treatment of diversion colitis by short-chain fatty acids. Prospective and double-blind study

Diminished production of short-chain fatty acids (SCFA) by altered flora has been suggested in the pathogenesis of diversion colitis (DC). We evaluated prospectively the effectiveness of SCFA irrigation in 13 patients with excluded colon (eight males, five females; mean age, 48 years). The causes of diversion were inflammatory bowel disease (n = 4), colonic cancer (n = 2), sigmoid diverticulitis with perforation (n = 3), ischiorectal abscess (n = 2), and miscellaneous (n = 2). Patients were given, twice a day for 14 days in a double-blind manner, a 60-ml enema containing either SCFA (acetate: 60 mmol/liter; propionate: 30 mmol/liter; and N-butyrate: 40 mmol/liter) (Group 1; n = 7) or isotonic NaCl (Group 2; n = 6). Endoscopy with biopsies was performed before starting the trial (D1) and 14 days later (D14). On D1 all patients had endoscopic and histologic findings suggestive of DC. No endoscopic or histologic changes were observed on D14 in either group. We conclude that endoscopic and histologic lesions of DC were not improved by SCFA irrigation during the 14 days.

Selective inhibition of prostaglandin endoperoxide synthase-1 (cyclooxygenase-1) by valerylsalicylic acid

Aspirin causes a time-dependent inhibition of prostaglandin endoperoxide H synthases (PGHS)-1 and -2 by acetylating active site serines present in both isozymes. In the case of PGHS-1, aspirin acetylation blocks cyclooxygenase activity, apparently by preventing arachidonate binding to the cyclooxygenase active site. With PGHS-2, acetylation does not block substrate binding but rather alters the enzyme in such a way that the acetylated form of PGHS-2 produces 15R-hydroxyeicosatetraenoic acid (15R-HETE) instead of the usual prostaglandin endoperoxide product. Based on these differences between PGHS-1 and PGHS-2, we reasoned that a salicylate ester containing an acyl group somewhat larger than the acetyl group of aspirin might be a selective inhibitor of PGHS-2. Accordingly, we prepared and tested eight different acyl salicylates as inhibitors of human (h) PGHS-1 and -2 expressed transiently in cos-1 cells. Valeryl(pentanoyl)salicylate (VSA) was the only compound in this series which showed isozyme selectivity, and, surprisingly, VSA inhibited hPGHS-1 much more effectively than hPGHS-2. Inhibition of hPGHS-1 by VSA was time-dependent. VSA also inhibited ovine PGHS-1 but did not inhibit the S530A mutant of ovine PGHS-1. This latter mutant, which lacks the active site serine hydroxyl group, is also refractory to inhibition by acetylsalicylate. Thus, we conclude that VSA acylates the active site serine of PGHS-1. VSA inhibited prostanoid synthesis by serum-starved murine NIH 3T3 cells which express only PGHS-1; in contrast, VSA caused only partial inhibition of prostanoid synthesis by serum-stimulated 3T3 cells which express both PGHS isozymes. Our results establish that VSA can be used as a reasonably selective inhibitor of PGHS-1.

Immunohistochemical study of 100 pancreatic tumors in 28 patients with multiple endocrine neoplasia, type I

One hundred pancreatic tumors ranging in size from 0.3 to 7 cm were studied in 28 patients (17 male and 11 female patients; mean age 35 years) with multiple endocrine neoplasia, type I. An immunohistochemical study was performed on deparaffinized sections using the following antibodies: neuron-specific enolase, chromogranin A or synaptophysin, insulin, glucagon, somatostatin, pancreatic polypeptide (PP), vasoactive intestinal peptide (VIP), gastrin, adrenocorticotropic hormone, alpha-subunit of human chorionic gonadotropin, gonadotropin-releasing factor, serotonin, and calcitonin. Among the 100 tumors (all multiple), seven were unclassified, 10 were plurihormonal, and 83 produced a predominant hormonal secretion (with 50-90% of the same cell type), including 37 "A-cell tumors" (glucagon), 27 "B-cell tumors" (insulin), 11 PP-cell tumors, one G-cell tumor (gastrin) and one vasoactive intestinal peptide (VIP)-cell tumor. These multiple tumors had a different predominant hormonal secretion in the same patient in 23 of the 28 cases. There was a preferential association of A-cell tumor and B-cell tumor. Hyperplasia of the islets of Langerhans was not detected in adjacent pancreas. Nesidioblastosis was observed in 30% of cases.

Impact of various emulsifiers on ALA bioavailability and chylomicron synthesis through changes in gastrointestinal lipolysis

Formulating healthy food rich in omega 3 fatty acids requires prior knowledge of the parameters influencing their bioavailability and their metabolic fate. In this context, we studied the effects of various emulsifiers widely used in the food industry, on the gastrointestinal lipolysis of flaxseed oil emulsions in an in vitro model and on the intestinal absorption and lymphatic secretion of alpha-linolenic acid (ALA) in rats. In vitro data showed that the emulsification of flaxseed oil with soya lecithin improved the gastric lipolysis of the oil (+30%), while the presence of Tween 80 or of sodium caseinate decreased it (-80% and -40%, respectively). The in vivo data demonstrated that the intestinal absorption and the lymphatic secretion of ALA were improved with soya lecithin (Cmax = 24 mg mL(-1)) and reduced in the presence of sodium caseinate (Cmax = 7 mg mL(-1)) compared to unemulsified flaxseed oil (Cmax = 16 mg mL(-1)); Tween 80 had no effect. In addition, the synthesized chylomicrons were notably larger and more numerous with soya lecithin whereas they were smaller in the presence of sodium caseinate (p < 0.05). This study shows that the intestinal bioavailability of ALA was increased by the emulsification of flaxseed oil with soya lecithin via an improved lipolysis, favouring the intestinal absorption of ALA and the secretion of many large chylomicrons in lymph.

Modification of enzymatic antioxidants in retinal microvascular cells by glucose or advanced glycation end products

Oxidative stress is one possible pathogenic mechanism to explain diabetic microangiopathy. In the present study, we determined the antioxidant enzyme activities in bovine retinal microvessels and cultured retinal microvascular cells: endothelial cells (BREC) and pericytes (BRP). We further investigated the effects of high glucose and advanced glycation end products (AGE) on these enzyme activities in BREC and BRP. Antioxidant enzyme activities in native retinal microvessels and BREC were quite similar but differed markedly from the BRP ones. High glucose decreased Se-GPx activity (about 20%) in BREC compared to mannitol. High concentrations of mannitol or NaCl increased Se-GPx activity (up to 40%) compared to control medium, suggesting that hyperosmolarity could regulate Se-GPx in BREC. No changes in antioxidant enzyme activities were observed when BRP were cultured with glucose or mannitol at high concentrations. AGE-BSA had no effect on enzyme activities in BREC, whereas 20 microM AGE-BSA increased catalase (40%) and superoxide dismutase (60%) activities in BRP. Differences in antioxidant enzyme activities observed between BREC and BRP, cultured with high concentrations of glucose or AGE, might help to explain their different behavior during the pathogenesis of diabetic retinopathy, i.e., early pericyte drop-out and late endothelial cell proliferation.

Lipomatous differentiation in ependymomas: a report of three cases and comparison with similar changes reported in other central nervous system neoplasms of neuroectodermal origin

Three cases of surgically removed ependymomas with lipomatous transformation of tumor cells are reported. Patients' ages were 13, 16, and 48 years at the time of operation. One patient's tumor was located in the third ventricle; the other two occupied paraventricular hemispheric white matter. Histologically all three cases fulfilled the criteria of ependymomas. In case 1, electron microscopy also confirmed this diagnosis, and preoperative radiologic studies (scans) suggested large amounts of lipids to be present in the tumor. Histologically, in all three cases many tumor cells contained fat droplets coalescing into a single large droplet, resulting in an appearance indistinguishable from adipocytes by conventional stains, but maintaining immunohistological positivity for glial fibrillary acidic protein and neuron-specific enolase in the cytoplasmic rims of the affected cells, attesting to their glial nature as opposed to being true adipocytes in a mixed glial/mesenchymal hamartoma. The alterations were also different from the "xanthomatous" changes seen in some gliomas. Lipomatous transformation of neuroectodermal tumor cells has been previously observed in neurocytomas, medulloblastomas, cerebellar and spinal cord astrocytomas, and primitive neuroectodermal tumors. Our three cases represent the first reported ependymomas with such changes. In medulloblastomas of adults, lipomatous changes have been found to signal relatively benign biologic behavior. So far, all three of our patients are doing well, but only more extended follow-up will show whether such benign behavior applies to lipomatous ependymomas as well.

Structural Investigation of Pd(II) in Concentrated Nitric and Perchloric Acid Solutions by XAFS

XAFS spectra of palladium(II) in concentrated HNO3/HClO4 acid mixtures have been recorded and analyzed. Structural parameters of the Pd(H2O)4(2+) complex and the mixed nitric Pd(NO3)2(H2O)2 complex, for the first time, were determined by the XAFS method. For pure 5 M HClO4 and for mixtures (0-0.3 M HNO3), the XAFS spectra of the 0.02 M Pd solutions are indeed very similar and originated from four Pd-O(w) equivalent distances. For the Pd(H2O)4(2+) square-planar aqua ion in strong perchloric acid, the use of an FEFF6 theoretical approach led to a first-shell Pd-O(w) distance of 2.00 (1) A and a Debye-Waller (DW) factor of sigma2 = 0.0030 (3) A2. Four water molecules are tightly bound to the Pd2+ ion in the equatorial plane, while two (or one) axial water molecules are weakly bound to the metal ion at 2.5 A with a DW factor of 0.015 (5) A2. For highly concentrated mixtures (4-6 M HNO3) and for pure concentrated (4-6 M) nitric acid as well as for crystalline powder Pd(NO3)2(H2O)2, the XAFS spectra are very similar and are determined by the mixed nitric complex Pd(NO3)2(H2O)2: four Pd-O near-equivalent distances of 2.01 (1) A from two H2O and two NO3 molecules with a total DW factor of sigma2 = 0.0037 (3) A2. Moreover, two Pd---N distances of 2.8-2.9 A were determined in the second coordination shell. Finally, for intermediate mixtures (1-3 M HNO3 in 5 M HClO4), the XAFS spectra are a superposition of the XAFS of Pd(H2O)4(2+) and Pd(NO3)2(H2O)2 complexes. The mean ligand number NO3(-) around Pd2+ has been calculated, and the XAFS results at pH close to zero confirm the spectrophotometric results previously published.

Albumin antioxidant capacity is modified by methylglyoxal

OBJECTIVE

Oxidative stress seems to play a major role in diabetic vascular complication development. Plasma albumin, via its thiol groups, is the main extracellular antioxidant molecule. Methylglyoxal (MG) is a very reactive dicarbonyl compound increased in diabetes which strongly modifies proteins by non-enzymatic glycosylation. The aim of this work was to study if MG could modify albumin antioxidant capacity.

METHODS

Bovine serum albumin was incubated with 1 mM MG at 37 degrees C for 7 days (MG-BSA). Albumin physico-chemical changes were evaluated by tryptophan autofluorescence measurement in the presence or in the absence of a quencher (acrylamide). Albumin antioxidant capacity was determined by thiol measurement using Ellman's reagent as well as in a cellular system (HeLa cells stressed by H2O2).

RESULTS

MG-BSA exhibited important modifications as shown by conformational changes, decreased tryptophan autofluorescence (30%) and significant thiol loss (40%). MG-BSA led to important modifications resulting in oxidation and loss of albumin antioxidant capacity. MG-BSA modifications were close to the one observed in albumin isolated from diabetic patients.

CONCLUSION

Our results suggest that deleterious effects induced by carbonyl stress in diabetes could also originate from a loss of albumin antioxidant capacity by dicarbonyl compound attack. The biological consequences of these findings have now to be investigated.

MLL amplification in myeloid leukemias: A study of 14 cases with multiple copies of 11q23

We here report the clinical, cytogenetic, fluorescence in situ hybridization (FISH), and Southern blot data on 14 patients with a myeloid malignancy and structural aberration of chromosome band 11q23 associated with overrepresentation or amplification of the MLL gene. The number of copies of MLL varied from three (two cases) to a cluster consisting of multiple hybridization spots. Together with previous reports, available data indicate that amplification of 11q23/MLL is a recurrent genetic change in myeloid malignancy. It affects mainly elderly patients and is often associated with dysplastic bone marrow changes or with complex karyotypic aberrations, suggestive of genotoxic exposure. It is associated with a poor prognosis. In addition, FISH analysis of nine cases with additional 11q probes showed that the overrepresented chromosomal region is generally not restricted to MLL, and Southern blot analysis indicated that amplification does not involve a rearranged copy of this gene. The significance of MLL amplification and the mechanisms by which it could play a role in leukemogenesis and/or disease progression remain to be elucidated.

Docosahexaenoic acid is a major n-3 polyunsaturated fatty acid in bovine retinal microvessels

The aim of this study was to purify microvessels from bovine retina and also to cultivate bovine retinal endothelial cells (BRECs) or intramural pericytes, to determine their fatty acid composition. Microvessels were obtained after Dounce homogenization of the retina followed by centrifugation on albumin cushion and finally microvessels in the pellet were trapped on a 100-microns nylon filter. Contamination of microvessel preparations by neuronal tissue, assessed after both microscopic examination and western blotting with a monoclonal antibody raised against rhodopsin, was minor. In the entire bovine retina, docosahexaenoic acid (DHA) represented 23.3% of the total fatty acids and there was about three times less arachidonic acid (AA) (8.2%) than DHA. In contrast, DHA and AA levels were almost equivalent in the retinal microvessels with approximately 10% of total fatty acids. When compared with intact microvessels, the DHA proportion of confluent monolayers of both BRECs or pericytes in primary cultures dropped to approximately 2% of the total fatty acids, whereas AA was unchanged. Culture medium supplementation with unesterified DHA (10 microM) restored the DHA proportion of BRECs close to the microvascular value at the expense of linoleic acid without affecting AA very much. In contrast, DHA supplementation in pericytes increased the DHA proportion of these cells at the expense of AA. In conclusion, DHA of intact microvessels represented 10% of the total fatty acids, which was close to the AA proportion. Mild DHA supplementation of BRECs or pericytes in primary cultures restored their DHA proportion to the original microvessel value. This high percentage of polyunsaturated fatty acids in retinal microvessels should allow us to test the hypothesis that oxidation products derived from these fatty acids may be involved in the pathogenic process leading to diabetic retinopathy.

The formation of tubular structures by endothelial cells is under the control of fibrinolysis and mechanical factors

This study highlights the importance of several factors involved in the formation of capillary-like structure formation (CLS) using Human Umbilical Vein Endothelial Cells (HUVEC) and Bovine Retinal Endothelial Cells (BREC) cultured on fibrin gels. The fibrin concentration inducing (CLS) was 0.5 mg/ml for HUVEC and 8 mg/ml for BREC. The high fibrin concentration required for the latter cells appeared necessary to counterbalance the extensive fibrinolysis of the gel by the BREC. Fibrin degradation products measured in the culture media showed that fibrin degradation was mandatory but not sufficient for CLS formation. Fibrin degradation acted in concert with the mechanical, concentration dependent properties of the gels to induce CLS. For example, HUVEC did not form CLS on a rigid fibrin of 8 mg/ml in spite of fibrinolysis. As cell reorganisation occurred, the fibrin was disrupted (HUVEC) or pleated (BREC) giving indirect proof of the development of mechanical forces. During CLS formation, an increasing amount of latent TGFbeta1 was measured in the medium (1000-1700 pg/ml). The active form of TGFbeta1 was not, however, detected and the addition of anti-TGF-beta1 antibody to the medium did not influence the formation of the CLS network. Yet, added activated TGF-beta1 led to the formation of less organised structures, that were completely abolished by the concomitant addition of the same anti-TGF-beta1 antibody. Thus, it is likely that TGF-beta1 secreted by the endothelial cells remained in its latent form. In conclusion, a balance between the mechanical properties of fibrin and the fibrinolytic activity of each cell type may regulate CLS formation in our models. We think that the high fibrinolitic activity of the BREC may represent a defense mechanism to protect the retina against thrombosis-induced damage in vivo.

Analysis of intrachromosomal homologous recombination in mammalian cell, using tandem repeat sequences

In all the organisms, homologous recombination (HR) is involved in fundamental processes such as genome diversification and DNA repair. Several strategies can be devised to measure homologous recombination in mammalian cells. We present here the interest of using intrachromosomal tandem repeat sequences to measure HR in mammalian cells and we discuss the differences with the ectopic plasmids recombination. The present review focuses on the molecular mechanisms of HR between tandem repeats in mammalian cells. The possibility to use two different orientations of tandem repeats (direct or inverted repeats) in parallel constitutes also an advantage. While inverted repeats measure only events arising by strand exchange (gene conversion and crossing over), direct repeats monitor strand exchange events and also non-conservative processes such as single strand annealing or replication slippage. In yeast, these processes depend on different pathways, most of them also existing in mammalian cells. These data permit to devise substrates adapted to specific questions about HR in mammalian cells. The effect of substrate structures (heterologies, insertions/deletions, GT repeats, transcription) and consequences of DNA double strand breaks induced by ionizing radiation or endonuclease (especially the rare-cutting endonuclease ISce-I) on HR are discussed. Finally, transgenic mouse models using tandem repeats are briefly presented.

In vitro and in vivo alterations of enzymatic glycosylation in diabetes

Carbohydrate composition changes of glycoconjugates constituting the glycocalix of microvascular cells could be involved in the alterations of cell-cell interactions observed in diabetic retinopathy. In this field, we have recently reported that advanced glycation end products (AGEs) modify galactose, fucose and sialic acid contents of specific cellular glycoproteins. To better understand the mechanisms involved in glycoprotein modifications in diabetes, we now investigate whether glucose and AGEs could affect the activities of enzymes involved in galactose, fucose and sialic acid metabolism : glycosyltransferases (synthesis) and glycosidases (catabolism). For this, bovine retinal endothelial cells (BREC) and pericytes (BRP) were cultured in the presence of high glucose concentration or AGEs, and cell glycosidase and glycosyltransferase activities were measured. The same enzymatic activities were studied in the whole retina from streptozotocin-treated rats. The results show that high glucose concentration did not affect glycosidases and glycosyltransferases neither in BRP nor in BREC except for galactosyltransferase activities in BREC. Concerning BRP, only galactosyltransferase activities were altered by AGEs. In contrast, in BREC, AGEs increased beta-D galactosidase, alpha-L fucosidase and neuraminidase activities (+37%, +56%, 36% respectively) whereas galactosyltransferase, fucosyltransferase and sialyltransferase activities were decreased (-11%, -24% and -23% respectively). In the retina from diabetic rats, beta-D galactosidase, alpha-L fucosidase and neuraminidase activities increased (+70%, +57%, +78% respectively) whereas fucosyl and sialyltransferase decreased (-7% and -15% respectively). The possible consequence of these enzymatic activity changes could be a defect in the carbohydrate content of some glycoproteins that might participate in the endothelial cell dysfunctions in diabetic microangiopathy.

Deletion of the 5'-ABL region: a recurrent anomaly detected by fluorescence in situ hybridization in about 10% of Philadelphia-positive chronic myeloid leukaemia patients

Inclusion of the BCR-ABL ES probe in routine cytogenetics led to the identification of a subgroup of Philadelphia positive (Ph+) chronic myeloid leukaemia patients characterized by a 5'-ABL deletion. This anomaly was observed in 5/51 cases (9.8%). Cytological and clinical data suggest that the 5'-ABL deletion may be associated with dysplastic features of polymorphonuclear cells and metamyelocytes and a short chronic phase duration.

Turning unreactive copper acetylides into remarkably powerful and mild alkyne transfer reagents by oxidative umpolung

Upon oxidation, copper acetylides formally behave as highly electrophilic species that could be trapped by a wide range of nucleophiles.

Role of the cyclic adenosine 3',5'-monophosphate and the phosphatidylinositol-Ca2+ cascades in mediating the effects of thyrotropin and iodide on hormone synthesis and secretion in human thyroid slices

There are two major known regulatory pathways in human thyrocytes: the phosphatidylinositol-Ca2+ cascade (PiP2 cascade) and the cAMP cascade. We study here the regulation of the PiP2 cascade by TSH, ATP, NaF, and bradykinin. Our data show that protein iodination and, thus, the synthesis of thyroid hormones in human thyroid is under the control of both the PiP2 cascade and the cAMP cascade. Activation of the PiP2 cascade by TSH (10 mU/mL), NaF, bradykinin, ionomycin, and 12-O-tetradecanoylphorbol-13-acetate stimulates iodide organification. Conversely, activation of the cAMP cascade by forskolin, TSH (0.3 mU/mL), and dibutyryl cAMP inhibits iodide organification. These metabolic effects are correlated to activations and inhibitions of the H2O2-generating system, showing that H2O2 is a limiting factor for protein iodination in these cells. The cascades also regulate in parallel the activity of the pentose phosphate pathway. The effects of various concentrations of TSH on H2O2 generation and [1-14C]glucose oxidation were tested, showing a dual effect with an inhibition of these metabolisms for low concentrations of TSH (that stimulate the cAMP cascade) and an activation for high concentrations of TSH (that stimulate the PiP2 cascade). The control of thyroid secretion differs from that of protein iodination, in that the cAMP cascade greatly enhances secretion, whereas the PiP2 cascade has no effect on basal secretion and even an inhibitory effect on TSH-stimulated secretion (1 mU/mL). We also demonstrate here the presence of an inhibitory effect of iodide on its own organification in human thyroid (Wolff-Chaikoff effect). This effect is probably mediated through an inhibition of the inositol trisphosphate response to TSH and of the H2O2 response to Ca2+.

Growth modulation of retinal microvascular cells by early and advanced glycation products

To investigate the possible implication of non-enzymatic glycosylation in the etiopathogenesis of the diabetic retinopathy, we studied the effect of early and advanced glycation products on the growth of retinal microvascular cells. Glucose modified products were obtained by incubating bovine serum albumin or fetal bovine serum with 0.5 M glucose for 10 (early glycation products: EG-BSA and EG-FBS, respectively) or 60 days (advanced glycation end products: AGE-BSA and AGE-FBS, respectively). Cell growth was assessed by cell counting and DNA content determination. EG-BSA or AGE-BSA significantly decreased pericyte proliferation after 8 days of culture (33 and 13% inhibition, respectively). Concerning endothelial cells, EG-BSA reduced proliferation to 40% whereas AGE-BSA increased it to 156% after 4 days of culture. The glucose-treated sera didn't exhibit the same growth effects, neither the EG-FBS nor the AGE-FBS significantly affected endothelial cell proliferation. Only the AGE-FBS showed a significant inhibitory effect on pericyte proliferation (40% inhibition). We conclude that retinal microvascular cell growth in vitro could be differently modulated by early and advanced glycation products. The inhibitory effect of AGEs observed on pericyte growth, suggests that glycoxidation could be implicated in the pericyte loss observed in diabetic retinopathy.

Dual regulation of glutathione peroxidase by docosahexaenoic acid in endothelial cells depending on concentration and vascular bed origin

Docosahexaenoic acid (DHA) has been reported to elicit oxidative stress, which in turn can induce antioxidant enzymes. Glutathione peroxidase (GPx) has received particular attention in this respect, as this enzyme is specifically required for the degradation of lipid hydroperoxides. Because we previously found that DHA could protect against oxidative stress when used in low amounts, we have compared the effect of a low (10 microM) versus high (100 microM) concentration of DHA on oxidant/antioxidant balance in bovine retinal and bovine aortic endothelial cells (BREC and BAEC). At 100 microM, DHA elicited a marked oxidative stress, as evidenced by high malondialdehyde levels and decreased plasmalogen phosphatidylethanolamine in both cells, and for BAEC only, a decrease of alpha-tocopherol. At 10 microM, DHA induced a slight increase of malondialdehyde in both cells, but did not affect alpha-tocopherol levels, which is indicative of a mild oxidative stress. In BREC, 10 microM DHA slightly but significantly decreased cytosolic GPx (cGPx) activity whereas 100 microM had no effect. In contrast, in BAEC, DHA 10 microM did not affect cGPx activity, whereas 100 microM increased it. The decreased cGPx activity in BREC was associated with a lower level of protein, suggesting a transcriptional and/or posttranscriptional effect. Phospholipid hydroperoxide GPx (PHGPx) activity was not modified by DHA at either concentration in BREC, whereas it was increased in BAEC when using 100 microM. Our results confirm that large amounts of DHA lead to oxidative stress, but do no support an antioxidant action of DHA at low concentration, in endothelium. Nevertheless, we showed that DHA can exert opposite effects on GPx regulation in endothelial cells, with regard to its concentration and to vascular bed origin.