Enzyme replacement prevents enamel defects in hypophosphatasia mice

Hypophosphatasia (HPP) is the inborn error of metabolism characterized by deficiency of alkaline phosphatase activity, leading to rickets or osteomalacia and to dental defects. HPP occurs from loss-of-function mutations within the gene that encodes the tissue-nonspecific isozyme of alkaline phosphatase (TNAP). TNAP knockout (Alpl-/-, aka Akp2-/-) mice closely phenocopy infantile HPP, including the rickets, vitamin B6-responsive seizures, improper dentin mineralization, and lack of acellular cementum. Here, we report that lack of TNAP in Alpl-/- mice also causes severe enamel defects, which are preventable by enzyme replacement with mineral-targeted TNAP (ENB-0040). Immunohistochemistry was used to map the spatiotemporal expression of TNAP in the tissues of the developing enamel organ of healthy mouse molars and incisors. We found strong, stage-specific expression of TNAP in ameloblasts. In the Alpl-/- mice, histological, mu CT, and scanning electron microscopy analysis showed reduced mineralization and disrupted organization of the rods and inter-rod structures in enamel of both the molars and incisors. All of these abnormalities were prevented in mice receiving from birth daily subcutaneous injections of mineral-targeting, human TNAP at 8.2?mg/kg/day for up to 44 days. These data reveal an important role for TNAP in enamel mineralization and demonstrate the efficacy of mineral-targeted TNAP to prevent enamel defects in HPP. (C) 2012 American Society for Bone and Mineral Research.

Anisotropic Brownian motion in ordered phases of DNA fragments

Using Fluorescence Recovery After Photobleaching, we investigate the Brownian motion of DNA rod-like fragments in two distinct anisotropic phases with a local nematic symmetry. The height of the measurement volume ensures the averaging of the anisotropy of the in-plane diffusive motion parallel or perpendicular to the local nematic director in aligned domains. Still, as shown in using a model specifically designed to handle such a situation and predicting a non-Gaussian shape for the bleached spot as fluorescence recovery proceeds, the two distinct diffusion coefficients of the DNA particles can be retrieved from data analysis. In the first system investigated (a ternary DNA-lipid lamellar complex), the magnitude and anisotropy of the diffusion coefficient of the DNA fragments confined by the lipid bilayers are obtained for the first time. In the second, binary DNA-solvent system, the magnitude of the diffusion coefficient is found to decrease markedly as DNA concentration is increased from isotropic to cholesteric phase. In addition, the diffusion coefficient anisotropy measured within cholesteric domains in the phase coexistence region increases with concentration, and eventually reaches a high value in the cholesteric phase.

Helical buckling of Skyrme-Faddeev solitons

Solitons in the Skyrme-Faddeev model on R-2 x S-1 are shown to undergo buckling transitions as the circumference of the S-1 is varied. These results support a recent conjecture that solitons in this field theory are well-described by a much simpler model of elastic rods.

Morphological evidence of neurotoxicity in retina after methylmercury exposure

The visual system is particularly sensitive to methylmercury (MeHg) exposure and, therefore, provides a useful model for investigating the fundamental mechanisms that direct toxic effects. During a period of 70 days, adult of a freshwater fish species Hoplias malabaricus were fed with fish prey previously labeled with two different doses of methylmercury (0.075 and 0.75 mu g g(-1)) to determine the mercury distribution and morphological changes in the retina. Mercury deposits were found in the photoreceptor layer, in the inner plexiform layer and in the outer plexiform layer, demonstrating a dose-dependent bioaccumulation. The ultrastructure analysis of retina revealed a cellular deterioration in the photoreceptor layer, morphological changes in the inner and outer segments of rods, structural changes in the plasma membrane of rods and double cones, changes in the process of removal of membranous discs and a structural discontinuity. These results lead to the conclusion that methylmercury is able to cross the blood-retina barrier, accumulate in the cells and layers of retina and induce changes in photoreceptors of H. malabaricus even under subchronic exposure. (c) 2012 Elsevier Inc. All rights reserved.

Identification of bacteria in drinking and purified water during the monitoring of a typical water purification system

Abstract Background A typical purification system that provides purified water which meets ionic and organic chemical standards, must be protected from microbial proliferation to minimize cross-contamination for use in cleaning and preparations in pharmaceutical industries and in health environments. Methodology Samples of water were taken directly from the public distribution water tank at twelve different stages of a typical purification system were analyzed for the identification of isolated bacteria. Two miniature kits were used: (i) identification system (api 20 NE, Bio-Mérieux) for non-enteric and non-fermenting gram-negative rods; and (ii) identification system (BBL crystal, Becton and Dickson) for enteric and non-fermenting gram-negative rods. The efficiency of the chemical sanitizers used in the stages of the system, over the isolated and identified bacteria in the sampling water, was evaluated by the minimum inhibitory concentration (MIC) method. Results The 78 isolated colonies were identified as the following bacteria genera: Pseudomonas, Flavobacterium and Acinetobacter. According to the miniature kits used in the identification, there was a prevalence of isolation of P. aeruginosa 32.05%, P. picketti (Ralstonia picketti) 23.08%, P. vesiculares 12.82%,P. diminuta 11.54%, F. aureum 6.42%, P. fluorescens 5.13%, A. lwoffi 2.56%, P. putida 2.56%, P. alcaligenes 1.28%, P. paucimobilis 1.28%, and F. multivorum 1.28%. Conclusions We found that research was required for the identification of gram-negative non-fermenting bacteria, which were isolated from drinking water and water purification systems, since Pseudomonas genera represents opportunistic pathogens which disperse and adhere easily to surfaces, forming a biofilm which interferes with the cleaning and disinfection procedures in hospital and industrial environments.

Importance of dietary n-3 hufa for eye development and cone formation along gilthead seabream sparus aurata larval development.

[EN] Being fish larvae visual feeders, vision plays an important role in larval orientation at first feeding (Blaxter, 1986). Larval trophic behaviour is closely related with the development of the visual capacity, which directly depends on retina organogenesis. In sparids, such as Pagrus major (Kawamura, 1984) and Pagrus auratus (Pankhurst, 1996), the most important changes in the eye structure occur along the lecitotrophic stage as a preparation for prey capture. Neuringer et al.,(1988) has established a critical role for n-3 polyunsaturated fatty acids and, particularly docosahexaenoic acid (DHA) in neural and retinal tissue functions in mammals. Similarly, in larval fish there is a high demand of DHA to form nervous membranes. Bell and Dick (1993) found photoreceptors in the eye, rods and cones accumulate and selectively retain DHA in external segments.Bell et al. (1995) found that feeding juvenile herring a DHA poor Artemia diet during the period of rod development resulted in impaired vision at low light intensities, when rod vision is essential.

Modellazione e simulazione di sistemi meccanici ad elevato numero di gradi di libertà mediante metodi non convenzionali e sistemi CAD

Recent developments in piston engine technology have increased performance in a very significant way. Diesel turbocharged/turbo compound engines, fuelled by jet fuels, have great performances. The focal point of this thesis is the transformation of the FIAT 1900 jtd diesel common rail engine for the installation on general aviation aircrafts like the CESSNA 172. All considerations about the diesel engine are supported by the studies that have taken place in the laboratories of the II Faculty of Engineering in Forlì. This work, mostly experimental, concerns the transformation of the automotive FIAT 1900 jtd – 4 cylinders – turbocharged – diesel common rail into an aircraft engine. The design philosophy of the aluminium alloy basement of the spark ignition engine have been transferred to the diesel version while the pistons and the head of the FIAT 1900 jtd are kept in the aircraft engine. Different solutions have been examined in this work. A first V 90° cylinders version that can develop up to 300 CV and whose weight is 30 kg, without auxiliaries and turbocharging group. The second version is a development of e original version of the diesel 1900 cc engine with an optimized crankshaft, that employ a special steel, 300M, and that is verified for the aircraft requirements. Another version with an augmented stroke and with a total displacement of 2500 cc has been examined; the result is a 30% engine heavier. The last version proposed is a 1600 cc diesel engine that work at 5000 rpm, with a reduced stroke and capable of more than 200 CV; it was inspired to the Yamaha R1 motorcycle engine. The diesel aircraft engine design keeps the bore of 82 mm, while the stroke is reduced to 64.6 mm, so the engine size is reduced along with weight. The basement weight, in GD AlSi 9 MgMn alloy, is 8,5 kg. Crankshaft, rods and accessories have been redesigned to comply to aircraft standards. The result is that the overall size is increased of only the 8% when referred to the Yamaha engine spark ignition version, while the basement weight increases of 53 %, even if the bore of the diesel version is 11% lager. The original FIAT 1900 jtd piston has been slightly modified with the combustion chamber reworked to the compression ratio of 15:1. The material adopted for the piston is the aluminium alloy A390.0-T5 commonly used in the automotive field. The piston weight is 0,5 kg for the diesel engine. The crankshaft is verified to torsional vibrations according to the Lloyd register of shipping requirements. The 300M special steel crankshaft total weight is of 14,5 kg. The result reached is a very small and light engine that may be certified for general aviation: the engine weight, without the supercharger, air inlet assembly, auxiliary generators and high pressure body, is 44,7 kg and the total engine weight, with enlightened HP pump body and the titanium alloy turbocharger is less than 100 kg, the total displacement is 1365 cm3 and the estimated output power is 220 CV. The direct conversion of automotive piston engine to aircrafts pays too huge weight penalties. In fact the main aircraft requirement is to optimize the power to weight ratio in order to obtain compact and fast engines for aeronautical use: this 1600 common rail diesel engine version demonstrates that these results can be reached.

Metodi di ottimizzazione morfologica nel progetto preliminare di propulsori aeronautici avanzati

The aim of this Doctoral Thesis is to develop a genetic algorithm based optimization methods to find the best conceptual design architecture of an aero-piston-engine, for given design specifications. Nowadays, the conceptual design of turbine airplanes starts with the aircraft specifications, then the most suited turbofan or turbo propeller for the specific application is chosen. In the aeronautical piston engines field, which has been dormant for several decades, as interest shifted towards turboaircraft, new materials with increased performance and properties have opened new possibilities for development. Moreover, the engine’s modularity given by the cylinder unit, makes it possible to design a specific engine for a given application. In many real engineering problems the amount of design variables may be very high, characterized by several non-linearities needed to describe the behaviour of the phenomena. In this case the objective function has many local extremes, but the designer is usually interested in the global one. The stochastic and the evolutionary optimization techniques, such as the genetic algorithms method, may offer reliable solutions to the design problems, within acceptable computational time. The optimization algorithm developed here can be employed in the first phase of the preliminary project of an aeronautical piston engine design. It’s a mono-objective genetic algorithm, which, starting from the given design specifications, finds the engine propulsive system configuration which possesses minimum mass while satisfying the geometrical, structural and performance constraints. The algorithm reads the project specifications as input data, namely the maximum values of crankshaft and propeller shaft speed and the maximal pressure value in the combustion chamber. The design variables bounds, that describe the solution domain from the geometrical point of view, are introduced too. In the Matlab® Optimization environment the objective function to be minimized is defined as the sum of the masses of the engine propulsive components. Each individual that is generated by the genetic algorithm is the assembly of the flywheel, the vibration damper and so many pistons, connecting rods, cranks, as the number of the cylinders. The fitness is evaluated for each individual of the population, then the rules of the genetic operators are applied, such as reproduction, mutation, selection, crossover. In the reproduction step the elitist method is applied, in order to save the fittest individuals from a contingent mutation and recombination disruption, making it undamaged survive until the next generation. Finally, as the best individual is found, the optimal dimensions values of the components are saved to an Excel® file, in order to build a CAD-automatic-3D-model for each component of the propulsive system, having a direct pre-visualization of the final product, still in the engine’s preliminary project design phase. With the purpose of showing the performance of the algorithm and validating this optimization method, an actual engine is taken, as a case study: it’s the 1900 JTD Fiat Avio, 4 cylinders, 4T, Diesel. Many verifications are made on the mechanical components of the engine, in order to test their feasibility and to decide their survival through generations. A system of inequalities is used to describe the non-linear relations between the design variables, and is used for components checking for static and dynamic loads configurations. The design variables geometrical boundaries are taken from actual engines data and similar design cases. Among the many simulations run for algorithm testing, twelve of them have been chosen as representative of the distribution of the individuals. Then, as an example, for each simulation, the corresponding 3D models of the crankshaft and the connecting rod, have been automatically built. In spite of morphological differences among the component the mass is almost the same. The results show a significant mass reduction (almost 20% for the crankshaft) in comparison to the original configuration, and an acceptable robustness of the method have been shown. The algorithm here developed is shown to be a valid method for an aeronautical-piston-engine preliminary project design optimization. In particular the procedure is able to analyze quite a wide range of design solutions, rejecting the ones that cannot fulfill the feasibility design specifications. This optimization algorithm could increase the aeronautical-piston-engine development, speeding up the production rate and joining modern computation performances and technological awareness to the long lasting traditional design experiences.

Computer simulations of charged systems in partially periodic geometries

This work presents algorithms for the calculation of the electrostatic interaction in partially periodic systems. The framework for these algorithms is provided by the simulation package ESPResSo, of which the author was one of the main developers. The prominent features of the program are listed and the internal structure is described. In the following, algorithms for the calculation of the Coulomb sum in three dimensionally periodic systems are described. These methods are the foundations for the algorithms for partially periodic systems presented in this work. Starting from the MMM2D method for systems with one non-periodic coordinate, the ELC method for these systems is developed. This method consists of a correction term which allows to use methods for three dimensional periodicity also for the case of two periodic coordinates. The computation time of this correction term is neglible for large numbers of particles. The performance of MMM2D and ELC are demonstrated by results from the implementations contained in ESPResSo. It is also discussed, how different dielectric constants inside and outside of the simulation box can be realized. For systems with one periodic coordinate, the MMM1D method is derived from the MMM2D method. This method is applied to the problem of the attraction of like-charged rods in the presence of counterions, and results of the strong coupling theory for the equilibrium distance of the rods at infinite counterion-coupling are checked against results from computer simulations. The degree of agreement between the simulations at finite coupling and the theory can be characterized by a single parameter gamma_RB. In the special case of T=0, one finds under certain circumstances flat configurations, in which all charges are located in the rod-rod plane. The energetically optimal configuration and its stability are determined analytically, which depends on only one parameter gamma_z, similar to gamma_RB. These findings are in good agreement with results from computer simulations.

Rod-coil copolymer structures

Skalenargumente werden verwendet, um Rod-Coil Copolymere mit fester Zusammensetzung von steifen Stäbchen und flexiblen Ketten zu studieren. In einem selektiven Lösungsmittel, in dem sich nur die Ketten lösen, bildet ein Rod-Coil Multiblock zylinderförmige Micellen aus aggregierten Stäbchen verbunden durch Kettenstücke. Die Stäbchen aggregieren, um Energie zu gewinnen. Dieser Prozeß wird durch den Entropieverlust der flexiblen Ketten ausgeglichen. Das Adsorptionsverhalten von Aggregaten aus parallel aneinandergelagerten, einzelnen Rod-Coil Diblöcken in selektivem Lösungsmittel wird anhand von erweiterten Skalenbetrachtungen diskutiert. Wenn ein solches Aggregat mit den Stäbchen parallel zur Oberfläche adsorbiert, verschieben sich die Stäbchen gegeneinander. Zusätzlich werden die Stabilität der adsorbierten Aggregate und andere mögliche Konfigurationen untersucht. Um einen Rod-Coil Multiblock mit variabler Zusammensetzung zu studieren, wird eine Feldtheorie entwickelt. Jedes Segment kann entweder steif oder flexibel sein. Das System zeigt drei Phasenzustände, offene Kette, amorphe Globule und flüssig-kristalline Globule. Beim Übergang von amorpher zu flüssig-kristalliner Globule steigt der Anteil an steifen Segmenten rapide an. Dieser Übergang wird durch die isotrope Wechselwirkung zwischen den steifen Segmenten und die anisotrope Oberflächenenergie der Globule verursacht.

Synthesis and characterization of new discotic polycyclic aromatic hydrocarbons and related pyrolytic nanostructures

Diskotische Hexa-peri-hexabenzocoronene (HBC) als molekulare, definierte graphitische Substrukturen sind bereits seit langem Gegenstand von Untersuchungen zu der Delokalisierung von π-Elektronen. In dieser Arbeit wurden zusätzlich Platin-Komplexe in das periphere Substitutionsmuster von HBC eingeführt. Dies führte zu einer Verbesserung der Emission von dem angeregten Triplett-Zustand in den Singulett-Grundzustand mit einer zusätzlichen Verlängerung der Lebensdauer des angeregten Zustandes. Zusätzlich erlaubte diese Konfiguration ein schnelles Intersystem-Crossing mittels einer verstärkten Spin-Orbit Kopplung, die sowohl bei tiefen Temperaturen, als auch bei Raumtemperatur exklusiv zu Phosphoreszenz (T1→S0) führte. Das Verständniss über solche Prozesse ist auch essentiell für die Entwicklung verbesserter opto-elektronischer Bauteile. Die Erstellung von exakt definierten molekularen Strukturen, die speziell für spezifische Interaktionen hergestellt wurden, machten eine Inkorporation von hydrophoben-hydrophilen, wasserstoffverbrückten oder elektrostatischen funktionalisierten Einheiten notwendig, um damit den supramolekularen Aufbau zu kontrollieren. Mit Imidazolium-Salzen funktionalisierte HBC Derivate wurden zu diesem Zwecke hergestellt. Eine interessante Eigenschaft dieser Moleküle ist ihre Amphiphilie. Dies gestattete die Untersuchung ihrer Eigenschaften in einem polaren Solvens und sowohl der Prozessierbarkeit als auch der Faserbildung auf Siliziumoxid-Trägern. Abhängig vom Lösungsmittel und der gewählten Konditionen konnten hochkristalline Fasern erhalten werden. Durch eine Substitution der HBCs mit langen, sterisch anspruchsvollen Seitenketten, konnte durch eine geeignete Prozessierung eine homöotrope Ausrichtung auf Substraten erreicht werden, was dieses Material interessant für photovoltaische Applikationen macht. Neuartige Polyphenylen-Metall-Komplexe mit diskotischen, linearen und dendritischen Geometrien wurden mittels einer einfachen Reaktion zwischen Co2(CO)8 und Ethinyl-Funktionalitäten in Dichlormethan hergestellt. Nach der Pyrolyse dieser Komplexe ergaben sich unterschiedliche Kohlenstoff-Nanopartikel, inklusive Nanoröhren, graphitischen Nanostäben und Kohlenstoff/Metall Hybrid Komplexe, die durch Elektronenmikroskopie untersucht wurden. Die resultierenden Strukturen waren dabei abhängig von der Zusammensetzung und Struktur der Ausgangssubstanzen. Anhand dieser Resultate ergeben sich diverse Möglichkeiten, um den Mechanismus, der zur Herstellung graphitischer Nanopartikel führt, besser zu verstehen.

Ornithophily in the genus Salvia L. (Lamiaceae)

This dissertation presents for the first time a survey of bird pollinated (ornithophilous) Salvia species. Within the approximately 1000 species of the worldwide distributed genus roughly 20% (186 spp.) are bird pollinated. Excepting four species in the Old World (South Africa and Madagascar), ornithophilous species are restricted to the New World where they represent about one third of the species. They occur mainly in higher altitudes (1500-3000m) and usually grow as shrubs or perennial herbs (97%). The bilabiate to tubular flowers are often red (at least 49%), averaging 35mm (7-130mm) in length and produce a large to medium volume of nectar with rather low sugar concentration. Pollination by sunbirds and white-eyes is documented in a South African species, and that by hummingbirds in 16 species of the New World (USA, Mexico, Guatemala and Bolivia). Beside pollinator observations, the functionality of the staminal levers, the process of pollen transfer and the fitting between flowers and birds are tested by inserting museum skins and metal rods into fresh flowers. The most surprising result is the finding of two different main pollen transfer mechanisms. In at least 54% of the species an active staminal lever mechanism enables pollen deposition on the birds body. This is illustrated in detail in the South African S. lanceolata at which birds were observed to release the lever mechanism and became dusted with pollen. In contrast, the lever mechanism in about 35% of the New World species is reduced in different ways. Pollen transfer by inactive ‘levers’ is demonstrated in detail in S. haenkei in Bolivia, at which four pollinating hummingbird species could be observed. The tubular corolla forced the birds in a specific position, thereby causing pollen transfer from the exserted pollen-sacs to the birds body. With respect to the floral diversity and systematic affiliation of the species, parallel evolution of ornithophily and lever reduction is likely. Considering that bird pollinated species might have derived from bee pollinated species and that the staminal levers have become secondarily inactive, it is concluded that the shift in pollinators induced phenotypic changes even disabling such a sophisticated structure as the staminal lever mechanism.

Therapeutic strategies for modulation of the vaginal microbiota

The vaginal microbiota of healthy women consists of a wide variety of anaerobic and aerobic bacteria, dominated by the genus Lactobacillus. The activity of lactobacilli is essential to protect women from genital infections and to maintain the natural healthy balance of the vaginal ecosystem. This role is particularly important during pregnancy because vaginal infection is one of the most important mechanisms for preterm birth. The most common vaginal disorder is bacterial vaginosis (BV). BV is a polymicrobial disorder, characterized by a depletion of lactobacilli and an increase in the concentration of other bacteria, including Gardnerella vaginalis, anaerobic Gram-negative rods, anaerobic Gram-positive cocci, Mycoplasma hominis, and Mobiluncus spp. An integrated molecular approach based on real-time PCR and PCR-DGGE was used to investigate the effects of two different therapeutic approaches on the vaginal microbiota composition. (i) The impact of a dietary supplementation with the probiotic VSL#3, a mixture of Lactobacillus, Bifidobacterium and Streptococcus strains, on the vaginal microbial ecology and immunological profiles of healthy women during late pregnancy was investigated. The intake was associated to a slight modulation of the vaginal microbiota and cytokine secretion, with potential implications in preventing preterm birth. (ii) The efficacy of different doses of the antibiotic rifaximin (100 mg/day for 5 days, 25 mg/day for 5 days, 100 mg/day for 2 days) on the vaginal microbiota of patients with BV enrolled in a multicentre, double-blind, randomised, placebo-controlled study was also evaluated. The molecular analyses demonstrated the ability of rifaximin 25 mg/day for 5 days to induce an increase of lactobacilli and a decrease of the BV-associated bacteria after antibiotic treatment, and a reduction of the complexity of the vaginal microbial communities. Thus, confirming clinical results, it represents the most effective treatment to be used in future pivotal studies for the treatment of BV.

Sequence-controlled synthesis of soluble oligo(p-benzamide)s

This work focused on the synthesis of novel monomers for the design of a series of oligo(p-benzamide)s following two approaches: iterative solution synthesis and automated solid phase protocols. These approaches present a useful method to the sequence-controlled synthesis of side-chain and main-chain functionalized oligomers for the preparation of an immense variety of nanoscaffolds. The challenge in the synthesis of such materials was their modification, while maintaining the characteristic properties (physical-chemical properties, shape persistence and anisotropy). The strategy for the preparation of predictable superstructures was devote to the selective control of noncovalent interactions, monodispersity and monomer sequence. In addition to this, the structure-properties correlation of the prepared rod-like soluble materials was pointed. The first approach involved the solution-based aramide synthesis via introduction of 2,4-dimethoxybenzyl N-amide protective group via an iterative synthetic strategy The second approach focused on the implementation of the salicylic acid scaffold to introduce substituents on the aromatic backbone for the stabilization of the OPBA-rotamers. The prepared oligomers were analyzed regarding their solubility and aggregation properties by systematically changing the degree of rotational freedom of the amide bonds, side chain polarity, monomer sequence and degree of oligomerization. The syntheses were performed on a modified commercial peptide synthesizer using a combination of fluorenylmethoxycarbonyl (Fmoc) and aramide chemistry. The automated synthesis allowed the preparation of aramides with potential applications as nanoscaffolds in supramolecular chemistry, e.g. comb-like-

Monte-Carlo simulation of hard spherocylinders under confinement

When a liquid crystal is confined to a cavity its director field becomes subject to competing forces: on the one hand, the surface of the cavity orients the director field (``surface anchoring''), on the other hand deformations of the director field cost elastic energy. Hence the equilibrium director field is determined by a compromise between surface anchoring and elasticity. One example of a confined liquid crystal that has attracted particular interest from physicists is the nematic droplet. In this thesis a system of hard rods is considered as the simplest model for nematic liquid crystals consisting of elongated molecules. First, systems of hard spherocylinders in a spherical geometry are investigated by means of canonical Monte Carlo simulations. In contrast to previous simulation work on this problem, a continuum model is used. In particular, the effects of ordering near hard curved walls are studied for the low-density regime. With increasing density, first a uniaxial surface film forms and then a biaxial surface film, which eventually fills the entire cavity. We study how the surface order, the adsorption and the shape of the director field depend on the curvature of the wall. We find that orientational ordering at a curved wall in a cavity is stronger than at a flat wall, while adsorption is weaker. For densities above the isotropic-nematic transition, we always find bipolar configurations. As a next step, an extension of the Asakura-Oosawa-Vrij model for colloid-polymer mixtures to anisotropic colloids is considered. By means of computer simulations we study how droplets of hard, rod-like particles optimize their shape and structure under the influence of the osmotic compression caused by the presence of spherical particles that act as depletion agents. At sufficiently high osmotic pressures the rods that make up the drops spontaneously align to turn them into uniaxial nematic liquid crystalline droplets. The nematic droplets or ``tactoids'' that so form are not spherical but elongated, resulting from the competition between the anisotropic surface tension and the elastic deformation of the director field. In agreement with recent theoretical predictions we find that sufficiently small tactoids have a uniform director field, whilst large ones are characterized by a bipolar director field. From the shape and director-field transformation of the droplets we estimate the surface anchoring strength.