Free radical scavenging properties of mannitol and its role as a constituent of hyaluronic acid fillers: a literature review.

Mannitol has both hydrating and antioxidant properties that make it an ideal excipient for use with hyaluronic acid (HA) fillers. This review examines the role of reactive oxygen species in the ageing process and their effects on both endogenous HA and HA products developed for aesthetic use. Evidence is presented to show that the free radical scavenging properties of mannitol provide it with a two-fold mechanism of action when combined with HA fillers: reducing the inflammation and swelling associated with the injection procedure itself, and preventing the degradation of the injected HA by free radicals. Mannitol also has a long- and well-established safety profile in both the food and pharmaceutical industry. Having established the rationale for using mannitol in combination with an HA filler, the products using this strategy are then reviewed. The addition of mannitol to HA fillers is a viable and safe option for improving both short- and long-term HA aesthetic effects.

Spin-crossover and liquid crystal properties in 2D cyanide-bridged Fe(II)-M(I/II) metalorganic frameworks.

Novel two-dimensional heterometallic Fe(II)-M(Ni(II), Pd(II), Pt(II), Ag(I), and Au(I)) cyanide-bridged metalorganic frameworks exhibiting spin-crossover and liquid crystal properties, formulated as {FeL(2)[M(I/II)(CN)(x)](y)}·sH(2)O, where L are the ligands 4-(4-alkoxyphenyl)pyridine, 4-(3,4-dialkoxyphenyl)pyridine, and 4-(3,4,5-trisalkoxyphenyl)pyridine, have been synthesized and characterized. The physical characterization has been carried out by means of EXAFS, X-ray powder diffraction, magnetic susceptibility, differential scanning measurements, and Mössbauer spectroscopy. The 2D Fe(II) metallomesogens undergo incomplete and continuous thermally induced spin transition at T(1/2) ≈ 170 K and crystal-to-smectic transition above 370 K.

Thermal- and light-induced spin crossover in novel 2D Fe(II) metalorganic frameworks {Fe(4-PhPy)(2)[M(II)(CN)(x)](y)}.sH(2)O: spectroscopic, structural, and magnetic studies.

Five novel two-dimensional coordination polymers {Fe(4PhPy)(2)[M(II)(CN)(4)]}.sH(2)O (4PhyPy = 4-phenylpyridine; 1: M(II) = Pd, s = 0; 2: M(II) = Ni, s = 0; 3: M(II) = Pt, s = 1) and {Fe(4PhPy)(2)[M(I)(CN)(2)](2)}.sH(2)O (4: M(I) = Ag, s = 1; 5: M(I) = Au, s = 0.5) exhibiting spin-crossover properties have been synthesized. They were characterized at various temperatures using X-ray absorption spectroscopy (XAS), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and magnetic susceptibility measurements. The occurrence of a cooperative thermal spin transition detected by the magnetic method is located at critical temperatures T(c)( downward arrow)/T(c)( upward arrow) = 163 K/203 K (1), 135 K/158 K (2), and 172 K/221 K (3), and a less cooperative one is located at T(c) = 188 K (4) and 225 K (5). Compounds 1-5 show an abrupt color change from yellow (high-spin (HS) state) to red (low-spin (LS) state) upon spin-state conversion. The dehydration of the compounds changes the type of the spin transition, making it more abrupt and shifting the critical temperature to higher temperatures. For 1 and 2, XAS provides local structural information on the contraction of the FeN(6) coordination sphere upon the HS-to-LS transition, in line with the magnetic results. Variable-temperature characterization of 1 by X-ray diffraction evidences the very abrupt phase transition with a large hysteresis. A light-induced spin conversion (LIESST effect) is detected by magnetic measurements in 1-5 below 70 K.

One-dimensional iron(II) compounds exhibiting spin crossover and liquid crystalline properties in the room temperature region.

A novel series of 1D Fe(II) metallomesogens have been synthesized using the ligand 5-bis(alkoxy)- N-(4 H-1,2,4-triazol-4-yl)benzamide (C n -tba) and the Fe(X) 2. sH 2O salts. The polymers obey the general formula [Fe(C n -tba) 3](X) 2. sH 2O [X = CF 3SO 3 (-), BF 4 (-); n = 4, 6, 8, 10, 12]. The derivatives with n = 4, 6 exhibit spin transition behavior like in crystalline compounds, whereas those with n = 8, 10, 12 present a spin transition coexisting with the mesomorphic behavior in the room-temperature region. A columnar mesophase has been found for the majority of the metallomesogens, but also a columnar lamellar mesophase was observed for other derivatives. [Fe(C 12-tba) 3](CF 3SO 3) 2 represents a new example of a system where the phase transition directly influences the spin transition of the Fe(II) ions but is not the driving energy of the spin crossover phenomenon. The compounds display drastic changes of color from violet (low-spin state, LS) to white (high-spin state, HS). The compounds are fluid, and it is possible to prepare thin films from them.

Mixed valency and magnetism in cyanometallates and Prussian blue analogues.

Prussian blue (PB) is a well-known archetype of mixed valency systems. In magnetic PB analogues {CxAy[B(CN)6]z}.nH2O (C alkali cation, A and B transition metal ions) and other metallic cyanometallates {Cx(AL)y[B(CN)8]z}.nH2O (L ligand), the presence of two valency states in the solid (either A-B, or A-A' or B-B') is crucial to get original magnetic properties: tunable high Curie temperature magnets; photomagnetic magnets; or photomagnetic high-spin molecules. We focus on a few mixed valency pairs: V(II)/V(III)/V(IV); Cr(II)/Cr(III); Fe(II)-Fe(III); Co(II)-Co(III); Cu(I)-Cu(II); and Mo(IV)/Mo(V), and discuss: (i) the control of the degree of mixed valency during the synthesis, (ii) the importance of mixed valency on the local and long-range structure and on the local and macroscopic magnetization, and (iii) the crucial role of the cyanide ligand to get these original systems and properties.

Combining two structural techniques on the micrometer scale: micro-XAS and micro-Raman spectroscopy.

X-ray absorption and Raman spectroscopies are complementary in the sense that both give very precise information about the local structure of a sample, both are not restricted to crystalline materials, and in both cases the volumes of the material probed are similar. The X-ray technique has the advantage of being element- and orbital-selective, and sensitive to orientational effects owing to polarization selection rules. In many cases, however, its analysis can present some ambiguity. Combining the two techniques on a micrometer scale could therefore be a very powerful method structurally. In this paper the experimental set-up developed at the LUCIA beamline and its application to a natural mineral are described.

A new glance at ruthenium sorption mechanism on hydroxy, carbonate, and fluor apatites: Analytical and structural studies.

The sorption mechanism of Ru3+ ions on hydroxy (HAp), carbonate (CO3HAp), and fluor apatites (FAp) has been studied in detail. Ru apatites were obtained by reaction of the apatites with RuCl3 in aqueous solution. The structure and composition of the ruthenium-modified apatites were studied by several techniques: elemental analysis, XRD, EXAFS, IR, NMR, SEM-EDS, TEM, and thermal analysis. The amount of Ru in the modified apatite varies from 7.8 to 10.5 wt% and is not related to the initial composition or the specific surface area of the apatite. The different characterization techniques show that in the Ru-modified apatites Ru is surrounded by six oxygen atoms and do not contain any chlorine. For Ru-HAp and Ru-CO3HAp the new phase is amorphous whereas it is crystalline for FAp. The catalytic oxidation ability is higher for Ru-HAp and Ru-CO3HAp compared to Ru-FAp apatite in the oxidation of benzylic alcohol.

Time-resolved study of the oxidation of ethanol by cerium(IV) using combined quick-XANES, UV-vis, and Raman spectroscopies.

Time-resolved X-ray absorption spectroscopy (Quick-XANES) has been combined with UV-vis and Raman spectroscopies to study the in situ reduction of Ce4+ to Ce3+ in ethanolic solution with a time resolution of ca. 4-5 s. For this purpose, a cam-driven oscillating double-crystal monochromator with a channel-cut crystal was combined with two spectrometers for UV-vis and Raman spectroscopies in a specialized cell which allows one to fit the optical pathways for all three spectroscopies individually. The results show that high-quality results can be obtained simultaneously, thus giving a detailed insight into the mechanisms of the investigated chemical reaction. The continuous release of nitrate and ethanol ligands from the initial Ce4+ into the solution finally leads to a trivalent cerium species which is only coordinated with water molecules after about 1800 s of reaction time.

Photoinduced ferrimagnetic systems in Prussian blue analogues C(I)xCo4[Fe(CN)6]y (C(I) = alkali cation). 4. Characterization of the ferrimagnetism of the photoinduced metastable state in Rb1.8Co4[Fe(CN)6]3.3-13H2O by K edges X-ray magnetic circular dichroism.

In Part 2 of this work, the electronic and local structure of the photoinduced metastable magnetic state of the Prussian blue analogue Rb1.8Co4[Fe(CN)6]3.3-13H2O were characterized. To determine directly the relative orientation of the magnetic moments of Co(II) and Fe(III) ions in the metastable state, and the nature of the exchange interaction between them, we performed X-ray magnetic circular dichroism (XMCD) experiments at the cobalt and iron K edges. We present the first direct experimental evidence of the antiferromagnetic interaction between the cobalt and the iron ions, leading to the ferrimagnetism of the photoinduced metastable state.

Conducting-polymer electrochemical switching as an easy means for control of the molecular properties of grafted transition metal complexes.

Copper(II) 3',4'-bis(N,N'-oxamato)terthiophene has been synthesized and electropolymerized. The copper(II)-complex centers are not affected by the polymerization process, which involves coupling between Calpha carbon atoms of the terthiophene units and leads to a new conjugated polymer consisting of polythiophene chains bearing bis(oxamato)-Cu(II) groups regioregularly grafted onto the polymer backbone. The polymer is stable with respect to polythiophene electroactivity, and no demetallation or modification of the Cu oxidation state occurs over a large potential range. In this material, the two moieties exhibit direct electronic interaction, which makes it possible to use the conductive polymer backbone as a molecular wire or a nanocontact capable of inputting to the bis(oxamato)-Cu(II) groups through the polythiophene-switching reaction. FTIR, XPS, and XAS spectroscopies have been used to study the effect of the state of the conducting polymer upon the properties of the copper(II) center (electron density, ligand field strength, size of cavity, force constants of some bonds). These properties can be controlled to some extent by the potential applied to this device. From the point of view of the copper(II) center, this effect is similar to the grafting of substituents with various electronic properties.

Reticulated hyaluronic acid implant in nonperforating trabecular surgery.

PURPOSE: To evaluate experimentally and clinically the tolerance and efficacy of a reticulated hyaluronic acid implant in nonperforating trabecular surgery (NPTS). SETTING: Bascom Palmer Eye Institute, Miami, Florida, USA, and Clinique Sourdille and Clinique Ophtalmologique Universitaire, Nantes, France. METHODS: In experimental surgery, NPTS was performed with and without a hyaluronic acid implant in 25 rabbit eyes. In a pilot study, the results of NPTS with a hyaluronic acid implant in 72 human eyes were retrospectively analyzed in terms of visual acuity, intraocular pressure (IOP), external filtration, postoperative inflammation, and gonioscopy. Mean follow-up was 13.8 months (range 6 to 24 months). RESULTS: In the experimental surgery, the rabbit eyes with the implant showed a different healing process than the eyes without the implant. The implant was slowly bioabsorbed and remnants were seen at the operative site (where the tissue was removed) up to day 56 postoperatively. This site was detectable at all histology study periods. Intraocular pressure reduction was longer in the implant group: greater than 5 months versus 3 weeks (P < .05). In the pilot study, visual acuity remained stable, IOP decreased from a mean preoperative level of 26.3 mm Hg +/- 5.22 (SD) to a mean postoperative level without treatment of 15.4 +/- 3.1 mm Hg (P < .0001). No external filtration was detected in 60 eyes, a slightly elevated conjunctiva was noted in 12 eyes. Postoperative inflammation (laser flare and cell measurements) was low. Gonioscopy consistently demonstrated the persistence of a decompression space behind the trabeculum. CONCLUSION: Comparative experimental surgery results showed excellent tolerance and efficacy in the rabbit eyes with a hyaluronic acid implant. Clinical results, to be confirmed by a randomized comparative study, also showed excellent biocompatibility and encouraging efficacy.

[Implantation of controlled-release 5-FU for the prevention of secondary cataract: preliminary study]. / Implant à relargage contrôlé de 5-FU pour la prévention de la cataracte secondaire: étude préliminaire.

To assess the efficacy of a control drug release implant coated with 5-Fu placed in the capsular bag for the prevention of the secondary cataract.

[Keratoprosthesis by posterior fixation and mechanical biocompatibility: determination of intraocular pressure provoking aqueous humor leak and/or extrusion]. / Kératoprotheses à fixation postérieure et biocompatibilité mécanique: détermination de la pression intraoculaire provoquant une fuite d'humeur aqueuse et/ou une extrusion.

The effect of a sudden increase in intraocular pressure (IOP) on Eye Bank eyes implanted with a posterior fixation keratoprosthesis PCL5 type (Lacombe) is evaluated. The IOP was artificially increased at a rate close to that observed in direct eye trauma. The critical pressure values causing aqueous humor leak and/or keratoprosthesis extrusion were compared to those found to blow up unoperated eyes. No statistical difference was found between operated and control eyes (6 pairs of eyes). This KPro type showed its efficacy for keratoprosthesis fixation.

[Reticulated polyethylene oxide for gel injection adjustable keratoplasty. Biocompatibility in critical situation]. / Oxyde de polyéthylène réticulé pour kératoplastie ajustable par injection de gel (GIAK). Biocompatibilité en situation critique.

BACKGROUND: GIAK is a surgical technique developed for the correction of myopia. We evaluated the biocompatibility of a gamma-ray crosslinked poly(ethylene oxide) gel in two critical situations. MATERIALS AND METHODS: In 3 rabbits, a 5 mm inner diameter annular channel of 1 mm width was delaminated at 80% corneal depth and a sterile gamma-ray crosslinked polyethylene oxide gel was injected in the channel. In cornea 1 (control), the annulus was centered on the corneal apex and the channel was fully filled with gel. In cornea 2, the delamination was purposely decentered and the channel was approximately 1 mm from the limbus at its closest point. In cornea 3, the centered channel was purposely partially filled. After a 6 month follow-up, the rabbits were sacrificed for histology. RESULTS: Histopathology showed the oval channel walls to be irregular and a slight thinning of the epithelium located above the implant but no abnormalities in the stromal thickness. No mononuclear, polynuclear cells or other signs of encapsulation or rejection were found around the polymer in any of the animals. In cornea 3, fibroblasts were found on the lateral sides of the hydrogel globules. No limbal neovascularization was observed over the 6 month period in any of the animals. CONCLUSIONS: The injected PEO gel followed intimately the delaminated stromal channel and was well tolerated in the cornea. The fibroblastic reaction found in partially filled channels is caused by the normal wound healing process and not by the hydrogel chemical properties.

Inclusion of the main pheromone component of Dacus oleae, 1,7-dioxaspiro[5,5]undecane, in beta-cyclodextrin.

The complex beta-cyclodextrin-1,7-dioxaspiro[5,5]undecane nonahydrate, C42H70O35.C9H16O2.9H2O, belongs to the class of beta-cyclodextrin dimeric-type complexes. The racemic guest molecule is present in a disordered position. Both enantiomers are located in two different regions inside the channel formed by the host dimers.

[Biodegradable controlled-release 5-FU implant in the surgery for glaucoma. Experimental study]. / Implant biodégradable à libération contrôlée de 5-FU dans la chirurgie du glaucome. Etude expérimentale.

BACKGROUND: 5-Fluorouracil (5-FU) is useful as an adjunct treatment for glaucoma filtering surgery. However, efficacy depends upon maintaining sustained drug levels, currently achieved by repeated daily injections of the drug for several days. To overcome this limitation, we designed a biodegradable implant for the sustained release of 5-FU. MATERIAL AND METHODS: The implant (0.79 mm diameter, 6 mm long, 2.2 mg weight) contains 0.66 mg of 5-FU and is loaded in a needle coupled to a custom-made instrument to permit subconjonctival insertion of the implant through a 2 mm wide snip incision. The in vitro and in vivo pharmacokinetics as well as the biocompatibility studies of the implants were assessed in the rabbit. RESULTS: No infection, inflammatory reaction or extrusion occurred. The implant released the drug at a constant rate of 1.20 micrograms/hr for over 18 days and totally biodegraded in less than 86 days. CONCLUSION: Implantation of the device, after laser sclerostomy or conventional trabeculectomy shows great potential for the treatment of glaucoma. To determine the implant's efficacy, additional studies in the cat are underway.

[Results of a 2-year animal experiment with reticulated polyethylene oxide intrastromal rings]. / Les résultats de 2 ans d'expérimentation animale des anneaux intrastromaux en polyoxyde d'éthylène réticulé.

Gel Injection Adjustable Keratoplasty (GIAK) is a technique previously described by G. Simon for the correction of myopia. Following pachometry, a 0.8 mm wide, 80% deep linear incision is performed 2.5 mm from the apex. Using a guide, a 1 mm wide, 5 mm diameter annular spatula is introduced to dissect an interlamellar canal and the crosslinked polyethylene oxide hydrogel is injected with a modified 23 gauge needle. The biocompatibility to 13 PEO batches was studied on 21 albino rabbits (Follow up 15 to 135 days). In nineteen, the cornea remained perfectly transparent. Two animals presented an infection at POD 1. Histopathology showed no endothelial deterioration, no anomaly of the thickness or of the cellular morphology around the injected zone. However some mononuclear cells were noticed surrounding the hydrogel in some rabbits together with thinning of the corneal epithelium anterior to the injected zone. A pilot refractive study was conducted on 5 cats using 2 PEO gels. One cat developed an infection following surgery. A second developed an inflammatory response with corneal neovascularization at POD 8. Thus, these animals were not included in the follow-up study which ranged from 6 to 28 months. Immediately after surgery, the refractive effect, measured with the Canon SK-1 digital autokeratometer, was 5.22 +/- 0.46 D (SD) of flattening. The long term effect (26 months) of the GIAK procedure appears to be stable and safe when using sterile PEO gels made of highly purified materials.