Synthesis and thermostructural studies of a CuFe(1-x)Cr(x)O(2) delafossite solid solution with 0

In this work, different CuFe(1-x)Cr(x)O(2) compositions with 0

[Professional practice evaluation in glaucoma]. / Evaluation des pratiques professionnelles (EPP) dans le glaucome.

Professional practice evaluation (PPE) and continuous medical education (CME) have been compulsory in France since July 2005. The objectives of PPE and CME are to increase the quality of care and to improve medical practice. Relatively easy to obtain, PPE is a self-evaluation of daily practice.

Liposomal formulation of a glycerolipidic prodrug for lymphatic delivery of didanosine via oral route.

Didanosine is a polar drug with poor membrane absorption and high hepatic first pass metabolism. This study aimed at developing a lipidic formulation of a glycerolipidic prodrug of didanosine in order to improve its bioavailability. In the course of a preformulation study, the glycerolipidic prodrug of didanosine was characterized by microscopy, DSC and XRDT. In anhydrous conditions, the prodrug displayed a polymorphic behaviour similar to that of triglycerides. Then, we evaluated three types of lipidic formulations (emulsions, mixed micelles and liposomes) in order to encapsulate the prodrug. Solubilities in water - even in the presence of taurocholate micelles - but also in some oils were very low (max 244 microg/mL) as the prodrug was found to be amphiphilic (log P=2). On the contrary, the prodrug was found to be perfectly incorporated in dipalmitoylphosphatidylcholine (DPPC) multilamellar liposomes up to a ratio of 1:5 (mol:mol) prodrug:DPPC as suggested by HPLC-UV and DSC experiments. Moreover, these liposomes could be freeze-dried whereas the chemical integrity of the prodrug was preserved. Then, the freeze-dried liposomal preparation could be formulated as gastro-resistant capsules to prevent didanosine from acidic degradation. Further experiments are on the way to evaluate in vitro the absorption of prodrug incorporated in liposomes by enterocytes.

A knock-in mouse model of congenital erythropoietic porphyria.

Congenital erythropoietic porphyria (CEP) is a recessive autosomal disorder characterized by a deficiency in uroporphyrinogen III synthase (UROS), the fourth enzyme of the heme biosynthetic pathway. The severity of the disease, the lack of specific treatment except for allogeneic bone marrow transplantation, and the knowledge of the molecular lesions are strong arguments for gene therapy. An animal model of CEP has been designed to evaluate the feasibility of retroviral gene transfer in hematopoietic stem cells. We have previously demonstrated that the knockout of the Uros gene is lethal in mice (Uros(del) model). This work describes the achievement of a knock-in model, which reproduces a mutation of the UROS gene responsible for a severe UROS deficiency in humans (P248Q missense mutant). Homozygous mice display erythrodontia, moderate photosensitivity, hepatosplenomegaly, and hemolytic anemia. Uroporphyrin (99% type I isomer) accumulates in urine. Total porphyrins are increased in erythrocytes and feces, while Uros enzymatic activity is below 1% of the normal level in the different tissues analyzed. These pathological findings closely mimic the CEP disease in humans and demonstrate that the Uros(mut248) mouse represents a suitable model of the human disease for pathophysiological, pharmaceutical, and therapeutic purposes.

Lentivirus-mediated gene transfer of uroporphyrinogen III synthase fully corrects the porphyric phenotype in human cells.

Congenital erythropoietic porphyria (CEP) is an inherited disease due to a deficiency in the uroporphyrinogen III synthase, the fourth enzyme of the heme biosynthesis pathway. It is characterized by accumulation of uroporphyrin I in the bone marrow, peripheral blood and other organs. The prognosis of CEP is poor, with death often occurring early in adult life. For severe transfusion-dependent cases, when allogeneic cell transplantation cannot be performed, the autografting of genetically modified primitive/stem cells may be the only alternative. In vitro gene transfer experiments have documented the feasibility of gene therapy via hematopoietic cells to treat this disease. In the present study lentiviral transduction of porphyric cell lines and primary CD34(+) cells with the therapeutic human uroporphyrinogen III synthase (UROS) cDNA resulted in both enzymatic and metabolic correction, as demonstrated by the increase in UROS activity and the suppression of porphyrin accumulation in transduced cells. Very high gene transfer efficiency (up to 90%) was achieved in both cell lines and CD34(+) cells without any selection. Expression of the transgene remained stable over long-term liquid culture. Furthermore, gene expression was maintained during in vitro erythroid differentiation of CD34(+) cells. Therefore the use of lentiviral vectors is promising for the future treatment of CEP patients by gene therapy.

[The palliative treatment of malignant esophageal stenosis and fistulae with self-expanding metal prostheses]. / Tratamiento paliativo de las estenosis y fístulas esofágicas malignas mediante prótesis metálicas autoexpandibles.

OBJECTIVE: To evaluate the efficiency of self-expanding metal stents (SES) for the palliative treatment of malignant oesophageal strictures and fistulas. MATERIAL AND METHODS: Fifty non-operable patients with malignant oesophageal strictures and/or fistulas were treated with SES placement. All patients had dysphagia, the mean degree for the studied group being 3.36. Ten patients presented associated tumoral fistula. Uncoated SES were placed for simple stenosis cases and coated SES for cancers with associated fistulas. RESULTS: A improvement in dysphagia was obtained in 47 patients (94%). The mean degree of dysphagia after the procedure was 1.12. In nine patients (90%) the fistula closed with resolution of the associated clinical picture. Complication were observed in six patients (12%), the perioperative mortality rate being 2%. During follow-up, twelve patients (25%) had malfunction of the stent, which was successfully treated in eight patients. CONCLUSION: SES are efficient for the palliative treatment of malignant oesophageal strictures and/or fistulas, but not commonly re-interventions are necessary to maintain a long-term functionality.

[Pseudophakia and aptitude of aviation personnel]. / Pseudophakie et aptitude du personnel navigant.

UNLABELLED: Because of sensorial disruptions, aphakia post-cataract surgery is a cause of unfitness for the job of aeronautics flying personnel. Its correction thanks to intraocular lenses and a correct functional check-up permit to reconsider the fitness through a derogation given by the competent authorities. EQUIPMENT AND METHODS: The authors realized a retrospective study on the 5 last years. 27 flying personnel, 24 to 76 years old, went through a cataract surgery with implantation. The check-up includes a chemical exam completed by a morphoscopic, coloured and spatial study. RESULTS AND DISCUSSION: The files are more or less well-documented according to their origin. The flying personnel have an average of 4,010 flying hours. The average post-operative hindsight is 30 months. 3 wear intraocular lenses of rear chamber among which 1 is multifocal. 7 were examinated at the CPEMPN with satisfying morphoscopic, coloured and luminous sense compatible with the fitness. 4 are declared permanent unfit (1 professional pilot with bad results, 1 private pilot with other pathologies, 1 inexperienced stewardess getting through the admission visit with insufficient post-operative hindsight, 1 professional pilot declared unfit for its military activity in the reserve). 4 are qualified with restriction. 20 are qualified without restriction. CONCLUSION: The correction of aphakia with intraocular lenses permits in most cases to obtain good functional results compatible with the flying aptitude.

Effects of aspirin on embolization in an arterial model of laser-induced thrombus formation.

This model of arterial thrombosis induced by laser was used to evaluate the effect of aspirin (Aspegic) on embolization. A partial occlusion was induced in small mesenteric arterioles (diameter 35-40 microns) with an Argon Laser. The laser induced the formation of a vessel wall lesion with damage of endothelial cells. Thrombus formed within seconds after the laser lesion and grew rapidly. Embolization began within the minute following the laser flash. Thrombus formation and embolization were repetitive phenomena. The duration of embolization was 6.50 +/- 0.84 min in the control group. Then the thrombus became stable and partially obstructed the vessel lumen. The administration of aspirin at three doses (50, 100, 200 mg/kg) by intramuscular injection, 15 min before the laser injury, induced three different phenomena: (1) an increase of the number of laser injuries required for the thrombus formation; (2) a dose-dependent decrease in the duration of embolization, and (3) a dose-dependent decrease in the number of emboli. The highest dose injected induced the strongest reduction in the duration of embolization and the number of emboli.

Could non steroidal anti-inflammatory drugs be used to potentiate L.M.W.H. activity in thrombosis? (Part II).

Thromboembolic diseases are one of the main cause of mortality. Heparin fractions obtained by chemical or enzymatical depolymerization of unfractionated heparin are now widely used in the prevention of those illness. However, curative dosages have bad side effects which could be avoid by the potentiation of the antithrombotic efficacy of non-active dosages. A previous study (4) has shown that a non-steroidal anti-inflammatory (NSAI) drug like Phenylbutazone could favour the antithrombotic efficacy of Fraxiparine at a very low dose. The aim of this study was then to determine if other NSAI elements could present the same or better proactive effects.

In vitro platelets/endothelial cells interactions in presence of acetylsalicylic acid at various dosages.

Venous endothelium is able to release in vitro substances which modifies platelet aggregation. A vascular fragment incubated in Michaelis buffer (pH 7.30), aliquoted and tested on platelet-rich-plasma partially inhibits the aggregometry parameters. Addition of acetylsalicylic acid (ASA) at ultra low dose (0.1 nM final solution in the incubation tube) presents a reversed effect on this inhibition. To explain this phenomenon, 6-keto-PGF1 alpha and von Willebrand factor were dosed in the incubation media. After determination of an active level of 6-keto-PGF1 alpha (200 pg/100 microliters), 2 series were made: series 1 included the values below 200 pg/100 microliters incubation media, series 2, the values above 200 pg/100 microliters incubation media. When the vascular fragment was incubated as described above, the results of aggregometry ratio for series 1 were: test A (without ASA): 0.84 +/- 0.18, test B1 (with 0.1 nM of ASA): 0.87 +/- 0.13. For series 2, they became: test A: 0.75 +/- 0.27, test B1: 0.93 +/- 0.16. Control was always: 1.00 +/- 0.00. For the same groups, 6-keto-PGF1 alpha values were: for series 1, test A: 81 +/- 57, test B1: 81 +/- 60 pg/100 microliters incubation medium, for series 2, test A: 596 +/- 495, test B1: 383 +/- 263 pg/100 microliters incubation medium. Analyses were also performed with 2 high doses of ASA (B2: 10(5) nM and B3: 10(6) nM final solution) in the same experimental conditions. In these groups, aggregation parameters were decreased (0.86 +/- 0.14 for 10(5) nM, 0.84 +/- 0.15 for 10(6) nM) as well as 6-keto-PGF1 alpha production (189 +/- 199 for 10(5) nM, 152 +/- 182 for 10(6) nM). For these two last ASA treatments, comparison of the results in groups set up according to the sensitive 6-keto-PGF1 alpha value (200 pg/100 microliters solution) showed no modification. So it seems that a certain reactive state, specific of ultra low dose treatment is necessary for the vascular endothelium to be sensitive at such treatment.

The role of essential vitamins in the development of thrombosis and hemorrhage--an experimental study.

To evaluate the action of essential vitamins on hemorrhage, coagulation and thrombosis, a multivitaminized solution was daily administered at three different doses for two weeks to male Wistar rats. Two experimental models were carried out: a venous thrombosis and an induced-hemorrhage model. Results indicate a low thrombogenic effect, a large and dose-dependent decrease of hemorrhage and no effect on coagulation. The observed effects on thrombosis and hemorrhage were not connected with an overdose of vitamins involving many secondary effects, since no blood viscosity parameters were modified. Three main hypotheses are envisaged to explain these results: a direct effect on platelet functions, an action on the leukocytic population, and a possible modification of the vessel wall response. However, further investigations are needed to specify the mechanisms involved.

Effects of immuno-potent drugs and their association with an unfractionated heparin on an experimental venous thrombosis.

Immuno-potent drugs are largely used in human medicine. The aim of this study was to determine the role of two immuno-modulators (sodium diethyl-dithiocarbamate, RU 41 740) and two immuno-suppressors (methylprednisolone, cyclosporin A) alone or in association with an unfractionated heparin (Calciparin), on an experimental venous thrombosis made by vena cava ligation in male Wistar rats. Each immuno-potent drug was administered for six days before the thrombus induction at the same dosage (10mg/kg b.w.), and the Calciparin, used as treatment of the thrombosis, was administered two hours after the thrombus induction at the dose of 1mg/kg b.w. Immuno-treatment potentiated thrombus formation: the increase in thrombus weight was greater with immuno-modulators (43% on average in comparison with placebo) than with immuno-suppressors (20%). In association with Calciparin the antithrombotic effect was also potentiated and more marked with the immuno-modulators than with immuno-suppressors. An increase in circulating monocytes was observed in all groups whether Calciparin was present or not. Coagulation tests were not affected by immuno-therapy. However, immuno-modulators led to an inhibition of platelet aggregation. In conclusion, this trial seems to show a probable effect of immunological cells in thrombosis and in the antithrombotic effect of heparin, but the mechanism involved is not yet determined.

Could proteolytic enzyme modulate the interaction platelets/vessel wall in presence of ASA at ultra low doses?

Acetylsalicylic acid (ASA) is known to act on platelets and vessel walls. At ultra low doses it reverses the inhibitory effects produced by a vascular fragment. Use of papain on normal platelets in vitro led to the appearance of platelet aggregation without collagen induction with a range of 20.25 +/- 28.91%. In the presence of vascular fragments (without ASA), this "spontaneous" aggregation remained but was reduced (13.26 +/- 27.73%). This effect was reversed by ASA treatment (29.41 +/- 24.17%). Reversion of vascular inhibition by ASA was not modified by papain.

Could non steroidal anti-inflammatory drugs be used to potentiate L.M.W.H activity in thrombosis? (Part I).

Heparin fractions are antithrombotic drugs prescribed for preventive treatment but their efficacy must be optimized to permit curative use without side effects. The present study was performed on 144 rats receiving a low molecular weight heparin (L.M.W.H), Fraxiparine, and a non steroidal anti-inflammatory drug (Phenylbutazone), which were injected simultaneously or separately. Neither Phenylbutazone nor L.M.W.H at their lowest dose (1 mg/kg) reduced thrombus size. However, administered together, they produced a significant limitation of thrombus growth. Variation in anti Xa activity limitation was only observed with the highest dose of Fraxiparine alone or in combination with Phenylbutazone (1 mg/kg) corresponding to its antithrombotic effect.

Comparative study of three recombinant hirudins with heparin in an experimental venous thrombosis model.

Three recombinant hirudins (r-hirudins) produced by genetic processes from Escherichia coli and yeast were studied. r-Hirudins could be an alternative treatment to heparin; so, the antithrombotic activity of these drugs should be compared to heparin, the reference substance, in an experimental venous thrombosis model. In this model, the effect of these r-hirudins on thrombus weight reduction were not identical. They varied depending on the original product (E. coli or yeast). The growth-inhibiting activity of r-hirudins on existing thrombi is not dose dependent, whereas that of heparin is. Moreover, in the conditions of this study, higher doses of heparin, but not of hirudins, increased the bleeding time. Although hirudin has limited applications for the time being, it seems an interesting anticoagulant drug, and the availability of r-hirudin opens new therapeutic anticoagulation perspectives.

Modifications of biological activities of heparin and fraxiparine induced by the size and the age of a thrombus. Experimental study.

Heparin and its fractions have often been tested on fresh experimental thrombosis. However in human clinic, drugs are administered not on fresh, but rather on old constituted thrombi. In order to evaluate the effects of antithrombotic agents in these conditions, both drugs (unfractionated heparin and Fraxiparine) were administered on 150 rats at different times and so, could take effect on thrombi with different ages. Heparin was more active as its fraction on fresh thrombi (2 hours old), but no more effects could be observed for all drugs when the thrombus was 52 hours old. Biological activities (A.P.T.T., anti-IIa and anti-Xa activities) decreased as the thrombi increased in weight and age.