Thuy Linh Tran

Aquaporins 6–12 in the human eye

Purpose:  Aquaporins (AQPs) are widely expressed and have diverse distribution patterns in the eye. AQPs 0–5 have been localized at the cellular level in human eyes. We investigated the presence of the more recently discovered AQPs 6–12 in the human eye.

Formulation and characterization of self-nanoemulsifying drug delivery systems containing monoacyl phosphatidylcholine.

The study investigated the use of monoacyl phosphatidylcholine (MAPC) in self-nanoemulsifying drug delivery system (SNEDDS). A D-optimal design was used to generate two sets of formulations containing long-chain (LC) or medium-chain (MC) glycerides, caprylocaproyl macrogol-8 glycerides (Labrasol), Lipoid S LPC 80 (LPC) (80% MAPC) and ethanol. The formulations were characterized using dynamic light scattering, microscopy, in vitro lipolysis and viscometric measurements. All LC formulations within the investigated range were predicted to generate polydisperse emulsions while MC formulations generated nanoemulsions with droplet sizes from 23 to 167 nm. Using LPC in MC formulations reduced the nanoemulsion droplet sizes in simulated gastric and intestinal media. The nanoemulsion droplet size of MC SNEDDS containing LPC was not affected by gastrointestinal pH, while the zeta potentials increased at low pH. During in vitro lipolysis, less fatty acids were released when LPC was incorporated into the formulations (2.05 ± 0.02 mmol reduced to 1.76 ± 0.05 mmol when incorporating 30% LPC). Replacing Labrasol by LPC increased the formulation dynamic viscosity from 57 ± 1 mPas (0% LPC) to 436 ± 8 mPas (35% LPC) at 25°C, however, this did not considerably prolong the formulation dispersion time. In conclusion, MC SNEDDS containing LPC are promising formulations when desiring to reduce the amount of synthetic surfactants and possibly modify the digestion rate.

Altered aquaporin expression in glaucoma eyes

Aquaporins (AQP) are channels in the cell membrane that mainly facilitate a passive transport of water. In the eye, AQPs are expressed in the ciliary body and retina and may contribute to the pathogenesis of glaucoma and optic neuropathy. We investigated the expression of AQP1, AQP3, AQP4, AQP5, AQP7 and AQP9 in human glaucoma eyes compared with normal eyes. Nine glaucoma eyes were examined. Of these, three eyes were diagnosed with primary open angle glaucoma; three eyes had neovascular glaucoma; and three eyes had chronic angle‐closure glaucoma. Six eyes with normal intraocular pressure and without glaucoma were used as control. Immunohistochemistry was performed using antibodies against AQP1, AQP3, AQP4, AQP5, AQP7 and AQP9. For each specimen, optical densities of immunoprecipitates were measured using Photoshop and the staining intensities were calculated. Immunostaining showed labelling of AQP7 and AQP9 in the nonpigmented ciliary epithelium and the staining intensities were significantly decreased in glaucoma eyes (p = 0.003; p = 0.018). AQP7 expression in the Müller cell endfeet was increased (p = 0.046), and AQP9 labelling of the retinal ganglion cells (RGC) showed decreased intensity (p = 0.037). No difference in AQP1, AQP4 and AQP9 expression was found in the optic nerve fibres. This study is the first investigating AQPs in human glaucoma eyes. We found a reduced expression of AQP9 in the retinal ganglion cells of glaucoma eyes. Glaucoma also induced increased AQP7 expression in the Müller cell endfeet. In the ciliary body of glaucoma eyes, the expression of AQP7 and AQP9 was reduced. Therefore, the expression of AQPs seems to play a role in glaucoma.

Myoepithelial carcinoma of the orbit: a clinicopathological and histopathological study.

Tran TL, Broholm H, Daugaard S, Fugleholm K, Poulsgaard L, Prause JU, Kennedy SM, Heegaard S. Myoepithelial carcinoma of the orbit: a clinicopathological and histopathological study. APMIS 2010; 118: 324–30.

In vitro and in vivo performance of monoacyl phospholipid-based self-emulsifying drug delivery systems

&NA; This study investigates the effect of monoacyl phospholipid incorporation on the in vitro and in vivo performance of self‐emulsifying drug delivery systems (SEDDS). Monoacyl phosphatidylcholine (Lipoid S LPC 80 (LPC)) was incorporated into four different fenofibrate (FF)‐loaded long‐chain SEDDS to investigate the impact of LPC on the emulsion droplet size, extent of digestion, colloidal structure evolution and drug precipitation during in vitro lipolysis simulating human conditions and drug bioavailability in a rat model. The four investigated SEDDS containing long‐chain glycerides, polyoxyl 35 castor oil or polyoxyl 8 caprylocaproyl glycerides with or without LPC. In situ synchrotron small/wide‐angle X‐ray scattering (SAXS/WAXS) was used to simultaneously real‐time monitor the kinetics of lamellar phase structure development and FF crystalline precipitation. Adding LPC increased the particle size and polydispersity of the dispersed SEDDS. The two LPC‐free SEDDS generated lamellar phase structures (L&agr;) with d‐spacing = 4.76 nm during digestion. Incorporating LPC into these systems inhibited the formation of lamellar phase structures. The amount of precipitated crystalline FF from the four SEDDS was similar during the first 15 min but differed during the last 45 min of in vitro digestion. The kinetics of colloidal structure development and FF precipitation was related to the digestion kinetics. The in vivo bioavailability data showed no significant differences between the four SEDDS, which correlates with the in vitro FF precipitation during the first 15 min of lipolysis. Thus, the presence of LPC, different emulsion droplet sizes and concentration of lamellar phase structures observed in vitro did not correlate with the FF absorption in rats. The study suggests that later time points of the in vitro lipolysis overestimated FF precipitation in rats because of the high enzyme activity, the lack of gastric and absorption steps, and the low bile salts and phospholipid concentrations of the in vitro model. Graphical abstract Figure. No caption available.

Monoacyl phosphatidylcholine inhibits the formation of lipid multilamellar structures during in vitro lipolysis of self-emulsifying drug delivery systems

&NA; The colloidal structures formed during lipolysis of self‐emulsifying drug delivery systems (SEDDS) might affect the solubilisation and possibly the absorption of drugs. The aim of the current study is to elucidate the structures formed during the in vitro lipolysis of four SEDDS containing medium‐chain glycerides and caprylocaproyl polyoxyl‐8 glycerides (Labrasol), with or without monoacyl phosphatidylcholine (MAPC). In situ synchrotron small‐angle X‐ray scattering (SAXS) was combined with ex situ cryogenic transmission electron microscopy (cryo‐TEM) and dynamic light scattering (DLS) to elucidate the generated structures. The SAXS scattering curves obtained during the lipolysis of MAPC‐free SEDDS containing 43–60% w/w Labrasol displayed a lamellar phase peak at q = 2.13 nm− 1 that increased with Labrasol concentration, suggesting the presence of multilamellar structures (MLS) with a d‐spacing of 2.95 nm. However, SEDDS containing 20–30% w/w MAPC did not form MLS during the lipolysis. The cryo‐TEM and DLS studies showed that MAPC‐free SEDDS formed coarse emulsions while MAPC‐containing SEDDS formed nanoemulsions during the dispersion in digestion medium. From the first minute and during the entire lipolysis process, SEDDS both with and without MAPC generated uni‐, bi‐, and oligo‐lamellar vesicles. The lipolysis kinetics in the first minutes of the four SEDDS correlated with an increased intensity of the SAXS curves and the rapid transformation from lipid droplets to vesicles observed by cryo‐TEM. In conclusion, the study elucidates the structures formed during in vitro lipolysis of SEDDS and the inhibitory effect of MAPC on the formation of MLS. Graphical abstract Figure. No caption available.

Aquaporin-1 Expression in Retinal Pigment Epithelial Cells Overlying Retinal Drusen.

Purpose: In the outer retina, age-related macular degeneration (AMD) results in reduced hydraulic conductivity in Bruchs membrane, possibly leading to altered water transport in retinal pigment epithelial (RPE) cells. We hypothesize that RPE cells may express aquaporin-1 (AQP1) to compensate for these changes. Therefore, we wanted to investigate the expression of AQP1 in RPE cells of human eyes with age-related maculopathy (ARM) and AMD, and eyes with tumour-associated drusen. Methods: Nine human eyes with ARM, 6 eyes with AMD and 9 eyes with choroidal malignant melanoma were examined for immunoreactivity to AQP1. AQP1 labelling in the RPE cells was evaluated for each drusen and grouped according to size and AQP1 labelling. AQP1 labelling in the RPE outside drusen was also evaluated. Results: AQP1 labelling was observed in the apical membrane of the RPE cells situated above drusen in all three groups. There was a significant association between AQP1 labelling and drusen size (p < 0.001), and AQP1 labelling was more frequently observed in large drusen. Conclusion: AQP1 was expressed in RPE cells covering drusen but not in RPE cells outside drusen. We suggest that AQP1 expression is upregulated in the cell membranes of RPE cells above drusen in order to alleviate the increased need for fluid transport across the growing drusen.

Aquaporins in the Eye

The major part of the eye consists of water . Continuous movement of water and ions between the ocular compartments and to the systemic circulation is pivotal for many physiological functions in the eye. The movement of water facilitates removal of the many metabolic products of corneal-, ciliary body-, lens- and retinal metabolism, while maintaining transparency in the optical compartments. Transport across the corneal epithelium and endothelium maintains the corneal transparency. Also, aqueous humour is continuously secreted by the epithelia of the ciliary body and maintains the intraocular pressure. In the retina, water is transported into the vitreous body and across the retinal pigment epithelium to regulate the extracellular environment and the hydration of the retina. Aquaporins (AQPs ) take part in the water transport throughout the eye.

Mapping the intermediate digestion phases of human healthy intestinal contents from distal ileum and caecum at fasted and fed state conditions

To investigate at the ultrastructural level, the colloidal phases formed in the lumen of the distal ileum and caecum of healthy adults.

Formulation of self-nanoemulsifying drug delivery systems containing monoacyl phosphatidylcholine and Kolliphor® RH40 using experimental design

Graphical Abstract Image, graphical abstractTriphenylphosphonium-modified paclitaxel nanocrystals were prepared for mitochondrial targeting strategy. Cellular uptake of NCs was through endocytosis pathway for avoiding efflux of P-glycoprotein (P-gp). After escaping from endosome, targeting NCs were apt to deliver PTX to mitochondria causing the decrease of mitochondrial membrane potential and then induced cancer cell apoptosis.