Cytomembrane visualization using Stokes parameter confocal microscopy.

A new, to the best of our knowledge, method for Stokes vector imaging is proposed to achieve imaging and dynamic monitoring of a non-labeled cytomembrane. In this work, a polarization state vector is described by a Stokes vector and expressed in chrominance space. A physical quantity called polarization chromaticity value (PCV) corresponding to a Stokes vector is used as the imaging parameter to perform Stokes vector imaging. By using the PCV imaging technique, the Stokes vector can be expressed in three-dimensional real space rather than in a Poincare sphere. Furthermore, a four-way Stokes parameter confocal microscopy system is designed to measure four Stokes parameters simultaneously and obtain micro-imaging. Label-free living onion cell membranes and their plasmolysis process are selected as the representative micro-anisotropy experimental analysis. It is proved that PCV imaging can perform visualization of cytomembranes, and further, microscopic orientation is demonstrated. The prospect of universal measurement of anisotropy details for analysis and diagnosis is provided.

Depolarizing metrics for plant samples imaging.

Optical methods, as fluorescence microscopy or hyperspectral imaging, are commonly used for plants visualization and characterization. Another powerful collection of optical techniques is the so-called polarimetry, widely used to enhance image contrast in multiple applications. In the botanical applications framework, in spite of some works have already highlighted the depolarizing print that plant structures left on input polarized beams, the potential of polarimetric methods has not been properly exploited. In fact, among the few works dealing with polarization and plants, most of them study light scattered by plants using the Degree of Polarization (DoP) indicator. Other more powerful depolarization metrics are nowadays neglected. In this context, we highlight the potential of different depolarization metrics obtained using the Mueller matrix (MM) measurement: the Depolarization Index and the Indices of Polarimetric Purity. We perform a qualitative and quantitative comparison between DoP- and MM-based images by studying a particular plant, the Hedera maroccana. We show how Mueller-based metrics are generally more suitable in terms of contrast than DoP-based measurements. The potential of polarimetric measurements in the study of plants is highlighted in this work, suggesting they can be applied to the characterization of plants, plant taxonomy, water stress in plants, and other botanical studies.

Diagnostic advances in synovial fluid analysis and radiographic identification for crystalline arthritis.

PURPOSE OF REVIEW: The present review addresses diagnostic methods for crystalline arthritis including synovial fluid analysis, ultrasound, and dual energy CT scan (DECT). RECENT FINDINGS: There are new technologies on the horizon to improve the ease, sensitivity, and specificity of synovial fluid analysis. Raman spectroscopy uses the spectral signature that results from a material's unique energy absorption and scatter for crystal identification. Lens-free microscopy directly images synovial fluid aspirate on to a complementary metal-oxide semiconductor chip, providing a high-resolution, wide field of view (∼20 mm) image. Raman spectroscopy and lens-free microscopy may provide additional benefit over compensated polarized light microscopy synovial fluid analysis by quantifying crystal density in synovial fluid samples. Ultrasound and DECT have good sensitivity and specificity for the identification of monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals. However, both have limitations in patients with recent onset gout and low urate burdens. SUMMARY: New technologies promise improved methods for detection of MSU and CPP crystals. At this time, limitations of these technologies do not replace the need for synovial fluid aspiration for confirmation of crystal detection. None of these technologies address the often concomitant indication to rule out infectious arthritis.

Desenvolvimento e caracterização de filmes e comprimidos bucais a base de pectina e goma gelana para liberação tópica de triancinolona / Development and characterization of films and buccal tablets based on pectin and gellan gum for the topical release of triamcinolone

O tratamento farmacológico de patologias bucais é conduzido, geralmente, por via de administração local. No entanto, devido ao pouco tempo de permanência do fármaco no local de ação, esse tratamento pode ser bastante comprometido. Assim, este trabalho teve por objetivo o desenvolvimento de formas farmacêuticas que proporcionem a liberação local de triancinolona na cavidade oral. Foram produzidos filmes e comprimidos mucoadesivos a partir de polímeros naturais como gelana e pectina. Os filmes bucais foram preparados por meio de evaporação do solvente (solvent casting) utilizando diferentes quantidades de polímeros. As matérias-primas e os filmes foram caracterizados fisico quimicamente utilizando espectroscopia vibracional (in-infravermelho com transformada de Fourier e Raman) e difração de raios X. As propriedades físicas e mecânicas dos filmes também foram avaliadas. Além disso, realizou-se os ensaios de mucoadesividade e de dissolução do fármaco. Os comprimidos foram preparados por com-pressão direta usando como base os polímeros naturais. Diferentes parâmetros em relação as misturas e as formulações foram avaliados tais como as propriedades de fluxo dos pós constituintes, peso médio, dureza, friabilidade e desintegração. Em relação aos filmes bucais, estes foram obtidos com sucesso através de um método simples, sem a utilização de agentes reticulantes, ácidos ou solventes orgânicos. Todos apresentaram bons resultados nas propriedades avaliadas, no entanto as formulações com quantidades intermediarias de polímeros foram as melhores. Dentre as formulações de comprimidos preparadas, apenas 4 apresentaram boas características, no entanto, os resultados dos ensaios de dissolução mostraram que estas formulações têm capacidade de agir como sistema de liberação controlada de fármacos

Pharmacological treatment of oral pathologies is usually conducted by local administration. However, due to the short time the drug stays in the site of action, this treatment can be quite compromised. Thus, the objective of this work was to develop pharmaceutical forms that pro-vide the local release of triamcinolone in the oral cavity. Mucoadhesive films and tablets were made from natural polymers such as gellan and pectin. The buccal films were prepared by sol-vent casting using different amounts of polymers. The raw materials and films were characte-rized physically chemically using vibrational spectroscopy (FTIR and Raman) and X-ray diffraction. The physical and mechanical properties of the films were also evaluated. In addi-tion, the mucoadhesive and drug dissolution tests were performed. The tablets were prepared by direct pressing with the natural polymers. Different parameters in relation to mixtures and formulations were evaluated such as the flow properties of the constituent powders, average weight, hardness, friability and disintegration. In relation to oral films, these were successfully obtained by a simple method, without the use of crosslinking agents, acids or organic solvents. All presented good results in the evaluated properties, however the formulations with interme-diate amounts of polymers were the best. Among the tablet formulations prepared, only 4 sho-wed good characteristics, however, the dissolution test results showed that these formulations have the ability to act as a controlled drug delivery system

Enhanced contrast and depth resolution in polarization imaging using elliptically polarized light.

Polarization gating is a popular and widely used technique in biomedical optics to sense superficial tissues (colinear detection), deeper volumes (crosslinear detection), and also selectively probe subsuperficial volumes (using elliptically polarized light). As opposed to the conventional linearly polarized illumination, we propose a new protocol of polarization gating that combines coelliptical and counter-elliptical measurements to selectively enhance the contrast of the images. This new method of eliminating multiple-scattered components from the images shows that it is possible to retrieve a greater signal and a better contrast for subsurface structures. In vivo experiments were performed on skin abnormalities of volunteers to confirm the results of the subtraction method and access subsurface information.

Aspectos Estruturais e Fitoquímicos de partes vegetativas de Costus spicatus (Jacq. ) Sw. (Costaceae) / Structural and Phytochemical aspect from vegetative part of Costus spicatus (Jacq. ) Sw (Costaceae)

As folhas de Costus spicatus são amplamente empregadas na medicina popular para o tratamento de várias doenças entre elas: malária, hepatite e doença do aparelho urinário. O objetivo deste trabalho foi identificar aspectos da anatomia dos órgãos vegetativos (folhas, caules, raízes e rizomas) associados à triagem fitoquímica visando contribuir com informações relevantes para o desenvolvimento de estudos taxonômicos e farmacológicos. A análise anatômica por meio da microscopia óptica e de varredura evidenciou folha anfi-hipoestomática, com estômatos e tricomas tectores filamentosos simples. O mesofilo é constituído por parênquima clorofiliano, que se divide em duas regiões intercaladas por cordão de fibras e feixes vasculares. O caule é do tipo atactostélico como no rizoma. A raiz é poliarca. Os testes histoquímicos indicaram a presença de amido, proteínas estruturais, alcaloides, cristais de oxalato de cálcio. A prospecção química com extratos hidroalcoólico e aquoso constatou a presença de saponinas, taninos, alcaloides, compostos fenólicos e heterosídeos cianogênicos.

The leaves of Costus spicatus are widely employed in folk medicine for the treatment of several diseases, including: malaria, hepatitis and urinary tract disease. The purpose of this paper was to identify aspects of the anatomy of vegetative organs (leaves, stems, roots and rhizomes) associated with phytochemical screening to contribute with relevant information for the development of taxonomic and pharmacological studies. The anatomic analysis through optical microscopy and scanning showed amphistomatic leaves with tetracitic type stomats and simple filamentous tector trichomes. Mesophyll is constituted by a chlorophyllian parenchyma, which is divided into two regions intersected by a strand of fibers and vascular bundles. The stem is atactostelic, such as for the rhizome. The root is polyarc. The histochemical tests indicated the presence of structural proteins, alkaloids, and calcium oxalate crystals. Chemical prospecting with hydroalcoholic and aqueous extracts attested the presence of saponins, tannins, alkaloids, phenolic compounds and heterosides as cyanogenic glucosides.

Concerted spatial-frequency and polarization-phase filtering of laser images of polycrystalline networks of blood plasma smears.

The complex technique of concerted polarization-phase and spatial-frequency filtering of blood plasma laser images is suggested. The possibility of obtaining the coordinate distributions of phases of linearly and circularly birefringent protein networks of blood plasma separately is presented. The statistical (moments of the first to fourth orders) and scale self-similar (logarithmic dependences of power spectra) structure of phase maps of different types of birefringence of blood plasma of two groups of patients--healthy people (donors) and those suffering from rectal cancer--is investigated. The diagnostically sensitive parameters of a pathological change of the birefringence of blood plasma polycrystalline networks are determined. The effectiveness of this technique for detecting change in birefringence in the smears of other biological fluids in diagnosing the appearance of cholelithiasis (bile), operative differentiation of the acute and gangrenous appendicitis (exudate), and differentiation of inflammatory diseases of joints (synovial fluid) is shown.

Identification and molecular interpretation of the effects of drug incorporation on the self-emulsification process using spectroscopic, micropolarimetric and microscopic measurements.

Addition of a drug to a self-emulsifying drug delivery system (SEDDS) can affect the emulsification process after administration, leading to variation in the emulsion droplet size formed and potentially its clinical behavior (Mercuri et al., Pharm. Res., 2011, 28, 1540-1551). However, the mechanisms involved and, in particular, the location of the drug within the system are poorly understood. Here, we have investigated the location of a model drug, ibuprofen, in the emulsions formed from a simple anhydrous SEDDS (soybean oil, Tween 80 and Span 80), using a range of physical characterization techniques. (1)H NMR studies showed an interaction between the drug and the polyoxyethylene chains of the surfactant Tween 80. Micropolarity assessment of the emulsion droplet interfacial region, using the chemical probes pyrene and Reichardt's dye, confirmed this interaction, and suggested that the drug was altering the microenvironment around the surfactants, and hence the behavior of the SEDDS with water during emulsification. Both dielectric spectroscopy and polarized light microscopy highlighted the differential behavior with water of placebo and drug-loaded SEDDS, also seen in the initial visual observational studies on the emulsification performance of the SEDDS. (1)H NMR studies with three other NSAIDs indicate that this effect is not confined to ibuprofen alone. The study has therefore indicated that the drug's influence on the emulsification process may be related to interactions within the microenvironment of the surfactant layer. Furthermore, such interactions may be usefully identified and characterized using a combination of micropolarity, spectroscopic and microscopic methods.

Application of microscopy in authentication of valuable Chinese medicine I--Cordyceps sinensis, its counterfeits, and related products.

Light and polarized microscope was applied to authenticate 32 Cordyceps and 6 artificial counterfeits and 8 fermented Cordyceps as well as 7 Cordyceps capsules available in Hong Kong markets. Results showed that transverse sections of stroma and powder of larvae can be used to differentiate C. sinensis from its counterfeits. The fermented Cordyceps are in powder form. Among the eight fermented Cordyceps collected, half of them were pure; three were a mixture of fermented Cordyceps and soya beans; one was a mixture of unknown plant tissues and soya beans. For the seven Cordyceps capsules, the powders of five samples were a mixture of fermented Cordyceps and soya beans; the powders of other two were a mixture of C. sinensis stroma powder and fermented Cordyceps. The study indicated that the microscopy is an unambiguous method that requests fewer sample for the authentication of valuable Chinese medicine-C. sinensis and its related products.

Density and morphometry of overall myenteric neurons population from the duodenum of diabetic rats (Rattus norvegicus) under ascorbic acid supplementation / Densidad y morfometría de la población total de neuronas mientéricas del duodeno de ratones diabéticos (Rattus norvegicus) tratados con ácido ascórbico

The objective of this work was to evaluate the overall myenteric neurons population from the duodenum of adult streptozotocin-induced diabetic rats supplemented with ascorbic acid (AA), a potent antioxidant. Fifteen 90-day-old rats were divided in groups: control (C), diabetic (D), diabetic treated with ascorbic acid (DA). After 120 days of experimental period duodenums were resected and processed as whole-mount preparations according to Giemsa's technique, which allowed us to evaluate neuronal density in an area of 8.96 mm² and measure the area of 500 neuronal cell bodies per group. It was observed a 32.55% reduction in neuronal density of group D when compared to group C (p<0.05). The density of spared neurons in group DA, in relation to group D, was not statistically different in this experimental model. No significant differences were found in neuronal areas when groups C and D or group D and DA were compared (p>0.05). These results lead us to conclude that the density of overall myenteric neurons population from the duodenum was reduced in diabetic rats (D), when compared to its control (C); and that diabetic rats supplemented with AA (DA) did not have their neuronal density preserved when compared to diabetic animals (D).

El objetivo de este trabajo fue evaluar la población total de neuronas mientéricas del duodeno de ratones adultos inducidos a diabetes por estreptozotocina, suplementados con ácido ascórbico (AA), un poderoso antioxidante. Quince ratones con 90 días de edad fueron divididos en los grupos: control (C), diabético (D) y diabético tratados con ácido ascórbico (DA). Después de 120 días de tratamiento con AA, los duodenos fueron resecados y procesados con el método de Giemsa, el cual permitió evaluar la densidad neuronal, en un área de 8,96 mm², y medir el área del soma de 500 neuronas por grupo. Se observó una reducción de 32,55% de la densidad neuronal del grupo D con respecto grupo C (p<0,05). La densidad de las neuronas observada en el grupo DA, en relación con el grupo D, no fue estadísticamente significativa en este modelo experimental. No fueron encontradas diferencias significativas en las áreas de neuronas, cuando los grupos C y D o el grupo D y DA (p>0,05) fueron comparados. Nuestros resultados permitieron concluir que la densidad de la población total de las neuronas mioentéricas del duodeno estuvo reducida en los ratones diabéticos comparados con los controles, mientras que, los ratones diabéticos suplementados con AA no mantuvieron su densidad neuronal cuando fueron comparados con los animales del grupo diabético.

Authentication of the 31 species of Toxic and Potent Chinese Materia Medica (T/PCMM) by microscopic technique, part 2: Three species of seed T/PCMM.

Toxic and Potent Chinese Materia Medica (T/PCMM) are being used more and more in the treatment of various diseases. In view of their toxic side effects and to ensure their safe use, accurate and reliable authentication is indispensable. However, identifying characteristics of T/PCMM are seldom reported, even though modern microscopy can provide ample, unique identifying characteristics from cells found in transverse sections and powders. In particular, no systematic authentication studies on seed T/PCMM have been conducted. In the course of our study on 31 T/PCMM originating from plants, animals, minerals, and secreta, an accurate and convenient method, based on microscopic techniques, has been developed and reported for the authentication of animal T/PCMM. The present study deals with detailed investigations on three species of seed T/PCMM, namely Semen Hyoscyami (Hyoscyamus niger L.), Semen Euphorbiae (Euphorbia lathyris L.), and Semen Strychni (Strychnos nux-vomica L.). The macroscopic characters are here described in detail, and the microscopic characters were conclusively determined by common and polarized light microscopy. Results showed that these three T/PCMM can be easily identified by the present method even when powdered and combined. Thus, the microscopic method is applicable for authentication of the earlier three T/PCMM, and the morphological and microscopic characteristics described here are proposed as parameters to establish the authenticity of these three T/PCMM.

Ultra-high resolution imaging by fluorescence photoactivation localization microscopy.

Biological structures span many orders of magnitude in size, but far-field visible light microscopy suffers from limited resolution. A new method for fluorescence imaging has been developed that can obtain spatial distributions of large numbers of fluorescent molecules on length scales shorter than the classical diffraction limit. Fluorescence photoactivation localization microscopy (FPALM) analyzes thousands of single fluorophores per acquisition, localizing small numbers of them at a time, at low excitation intensity. To control the number of visible fluorophores in the field of view and ensure that optically active molecules are separated by much more than the width of the point spread function, photoactivatable fluorescent molecules are used, in this case the photoactivatable green fluorescent protein (PA-GFP). For these photoactivatable molecules, the activation rate is controlled by the activation illumination intensity; nonfluorescent inactive molecules are activated by a high-frequency (405-nm) laser and are then fluorescent when excited at a lower frequency. The fluorescence is imaged by a CCD camera, and then the molecules are either reversibly inactivated or irreversibly photobleached to remove them from the field of view. The rate of photobleaching is controlled by the intensity of the laser used to excite the fluorescence, in this case an Ar+ ion laser. Because only a small number of molecules are visible at a given time, their positions can be determined precisely; with only approximately 100 detected photons per molecule, the localization precision can be as much as 10-fold better than the resolution, depending on background levels. Heterogeneities on length scales of the order of tens of nanometers are observed by FPALM of PA-GFP on glass. FPALM images are compared with images of the same molecules by widefield fluorescence. FPALM images of PA-GFP on a terraced sapphire crystal surface were compared with atomic force microscopy and show that the full width at half-maximum of features approximately 86 +/- 4 nm is significantly better than the expected diffraction-limited optical resolution. The number of fluorescent molecules and their brightness distribution have also been determined using FPALM. This new method suggests a means to address a significant number of biological questions that had previously been limited by microscope resolution.

AB-type lectin (toxin/agglutinin) from mistletoe: differences in affinity of the two galactoside-binding Trp/Tyr-sites and regulation of their functionality by monomer/dimer equilibrium.

Viscumin of mistletoe (Viscum album L.) has a concentration-dependent activity profile unique to plant AB-toxins. It starts with lectin-dependent mitogenicity and then covers toxicity and cell agglutination, associated with shifts in the monomer/dimer equilibrium. Each lectin subunit harbors two sections for ligand contact. In the dimer, the B-chain sites in subdomain 2 gamma (designated as the Tyr-sites) appear fully accessible, whereas Trp-sites in subdomain 1 alpha are close to the dimer interface. It is unclear whether both types of sites operate similarly in binding glycoligands in solution. By systematically covering a broad range of lactose/lectin ratio in isothermal titration calorimetry, we obtained evidence for two sites showing dissimilar binding affinity. Intriguingly, the site with higher affinity was only partially occupied. To assign the observed properties to the Trp/Tyr-sites, we next performed chemically induced dynamic nuclear polarization measurements of Trp and Tyr accessibility. A Tyr signal, but not distinct Trp peaks, was recorded when testing the dimer. Lactose-quenchable Trp peaks became visible on the destabilization of the dimer by citraconylation, intimating Trp involvement in ligand contact in the monomer. Fittingly, Tyr acetylation but not mild Trp oxidation reduced the dimer hemagglutination activity and the extent of binding to asialofetuin-Sepharose 4B. Altogether, the results attribute lectin activity in the dimer primarily to Tyr-sites. Full access to Trp-sites is gained on dimer dissociation. Thus, the monomer/dimer equilibrium of viscumin regulates the operativity of these sites. Their structural divergence affords the possibility for differences in ligand selection when comparing monomers (Tyr- and Trp-sites) with dimers (primarily Tyr-sites).

Collagen birefringence in skin repair in response to red polarized-laser therapy.

We use the optical path difference (OPD) technique to quantify the organization of collagen fibers during skin repair of full-thickness burns following low-intensity polarized laser therapy with two different polarization incidence vectors. Three burns are cryogenerated on the back of rats. Lesion L(parallel) is irradiated using the electric field vector of the polarized laser radiation aligned in parallel with the rat's occipital-caudal direction. Lesion L(perpendicular) is irradiated using the electric field vector of the polarized laser radiation aligned perpendicularly to the aforementioned orientation. Lesion C is untreated. A healthy area labeled H is also evaluated. The tissue samples are collected and processed for polarized light microscopy. The overall finding is that the OPD for collagen fibers depends on the electric field vector of the incident polarized laser radiation. No significant differences in OPDs are observed between L(parallel) and H in the center, sides, and edges of the lesion. Lesions irradiated using the electric field vector of the polarized laser radiation aligned in parallel with the rat's occipital-caudal direction show higher birefringence, indicating that collagen bundles in these lesions are more organized.

Neurotoxic zinc translocation into hippocampal neurons is inhibited by hypothermia and is aggravated by hyperthermia after traumatic brain injury in rats.

Hypothermia reduces excitotoxic neuronal damage after seizures, cerebral ischemia and traumatic brain injury (TBI), while hyperthermia exacerbates damage from these insults. Presynaptic release of ionic zinc (Zn2+), translocation and accumulation of Zn2+ ions in postsynaptic neurons are important mechanisms of excitotoxic neuronal injury. We hypothesized that temperature-dependent modulation of excitotoxicity is mediated in part by temperature-dependent changes in the synaptic release and translocation of Zn2+. In the present studies, we used autometallographic (AMG) and fluorescent imaging of N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ) staining to quantify the influence of temperature on translocation of Zn2+ into hippocampal neurons in adult rats after weight drop-induced TBI. The central finding was that TBI-induced Zn2+ translocation is strongly influenced by brain temperature. Vesicular Zn2+ release was detected by AMG staining 1 h after TBI. At 30 degrees C, hippocampus showed almost no evidence of vesicular Zn2+ release from presynaptic terminals; at 36.5 degrees C, the hippocampus showed around 20% to 30% presynaptic vesicular Zn2+ release; and at 39 degrees C vesicular Zn2+ release was significantly greater (40% to 60%) than at 36.5 degrees C. At 6 h after TBI, intracellular Zn2+ accumulation was detected by the TSQ staining method, which showed that Zn2+ translocation also paralleled the vesicular Zn2+ release. Neuronal injury, assessed by counting eosinophilic neurons, also paralleled the translocation of Zn2+, being minimal at 30 degrees C and maximal at 39 degrees C. We conclude that pathological Zn2+ translocation in brain after TBI is temperature-dependent and that hypothermic neuronal protection might be mediated in part by reduced Zn2+ translocation.

Effect of the type of dietary fat on biliary lipid composition and bile lithogenicity in humans with cholesterol gallstone disease.

OBJECTIVE: The effect of the type of dietary fat on bile lipids and lithogenicity is unclear. This study compared the effects of two dietary oils that differed in fatty acid profile on biliary lipid composition in humans. METHODS: Female patients who had cholesterol gallstones and were scheduled for elective cholecystectomy were studied. For 30 d before surgery, subjects were kept on diets that contained olive oil (olive oil group, n = 9) or sunflower oil (sunflower oil group, n = 9) as the main source of fat. Gallbladder bile and stones were sampled at surgery. After cholecystectomy, duodenal samples were collected by nasoduodenal intubation during fasting and after administration of mixed liquid meals that included the corresponding dietary oil. Duodenal and gallbladder bile samples were analyzed for cholesterol, phospholipids, and total bile acids by established methods. Individual bile acid conjugates in gallbladder bile were measured by high-performance liquid chromatography. Gallstones were analyzed by semiquantitative polarizing light microscopy. RESULTS: Despite marked differences in the absolute concentration of biliary lipids and total lipid content, manipulation of dietary fat ingestion did not influence the cholesterol saturation or the profile of individual bile acids in gallbladder bile obtained from patients who had gallstones. All but one subject had mixed cholesterol stones. A cholesterol saturation index of hepatic bile in fasted cholecystectomized patients was similar in both dietary groups and indicative of supersaturation. In response to the test meal, the cholesterol saturation index decreased significantly in patients given the olive oil diet, reaching values lower than one at 120 min postprandially. In contrast, hepatic bile secreted by patients who consumed sunflower oil appeared supersaturated (cholesterol saturation index >1.5) throughout the experiment. CONCLUSIONS: Our results suggest that the type of dietary fat habitually consumed can influence bile composition in humans. In gallbladder, this influence was noted in the presence of more concentrated bile in the olive oil group. However, this was not translated into a modification of cholesterol saturation, which is likely due to the fact that cholesterol gallstones were present by the time the dietary intervention started. The finding that a typical postprandial variation in hepatic bile lithogenicity occurred only in olive oil patients was revealing. While keeping in mind the methodologic limitations of this part of the study, some gastrointestinal and metabolic mechanisms for this effect are discussed.

Preparation and evaluation of floating risedronate sodium Gelucire 39/01 matrices.

Incorporation of bisphosphonates in the lipid reduces gastric irritation. Only gastric retention with sustained release allows the drug to reach the duodenum and jejunum and improves the availability of bisphosphonates. Risedronate sodium and Gelucire 39/01 floating matrices were prepared using melt solidification. The sustained release floating matrices were evaluated for in vitro and in vivo floating ability and in vitro drug release. Ageing of the matrices was studied by differential scanning calorimetry, hot stage polarizing microscopy, scanning electron microscopy and in vitro drug release. Ageing causes changes in the crystal structure of Gelucire, which is responsible for an increase in drug release.

A novel cubic phase of medium chain lipid origin for the delivery of poorly water soluble drugs.

The existence of a novel cubic liquid crystalline phase is described within the pseudo-ternary system comprising lauric acid, monolaurin, and simulated endogenous intestinal fluid (SEIF). This phase behaviour has been characterized using cross-polarizing light microscopy (CPLM), and the structure of the cubic phase identified by small angle X-ray scattering (SAXS). The presence of the cubic phase was found to be temperature sensitive within the 20-37 degrees C range making it putative material for in situ gelation purposes. The cubic phase was shown to have a high capacity to solubilise a model poorly water-soluble drug, cinnarizine, and initial in vitro release data highlight the potential of this phase to provide sustained release. Absorption of cinnarizine from the cubic phase was studied in an unconscious rat model via duodenal administration and blood sampling via the carotid artery. The rate of absorption was significantly reduced when compared to a simple suspension formulation, a likely combination of retarded erosion of the cubic phase together with hindered drug release from the cubic matrix. The results of this study suggest that this cubic phase may potentially be of benefit in the delivery of poorly water-soluble compounds due to its high loading capacity and potential for sustained release. The ability to manipulate this system using temperature may warrant further interest in delivery applications via other routes of administration.

Cristalização de lipídios estruturados obtidos a partir de gordura do leite e óleo de milho / Crystallization of structured lipids from milkfat and corn oil

A partir da mistura de óleos e gorduras e de posterior interesterificação podem ser obtidos lipídios estruturados, que são compostos que apresentam características físicas, químicas e nutricionais diferentes daquelas dos lípidios que lhes deram origem. As principais propriedades físicas destes lipídios, como consistência e plasticidade, podem ser infleunciadas por sua estrutura cristalina. O objetivo deste trabalho foi observar modificações na estrutura cristalina de lipídios estruturados obtidos a partir de gordura do leite e óleo de milho. As curvas de cinética de cristalização foram construídas a partir do conteúdo de gordura sólida das amostras em função do tempo. A utilização do cálculo dos parâmetros de Avrami permitiu determinar a velocidade de cristalização e os tipos de nucleação e dos cristais formados...

Effect of fiber orientation in dynamic FTIR study on native cellulose.

The properties of cellulose materials are highly dependent on the interactions between and within the cellulose chains mainly related to inter- and intramolecular hydrogen bonds. To investigate the deformation behavior of cellulose and its relation to molecular straining, cellulose sheets with different fiber orientations were studied by dynamic FTIR spectroscopy. The sheets were stretched sinusoidally at low strains while being irradiated with polarized infrared light. It is shown that the polarization direction determines the dynamic IR response to a higher extent than the fiber direction in the sample sheets. Different polarization modes give different dynamic signals, allowing conclusions to be drawn on the structural orientation of submolecular groups in the cellulose molecules. The bands in the spectra mainly affected by the deformation of the sheets were derived from skeletal vibrations that include the C-O-C bridge connecting adjacent rings and from the hydrogen bonds. The conclusion that these groups are the ones that are mainly deformed under load has thereby experimentally demonstrated the theoretical calculations from Tashiro and Kobayashi [Tashiro, K.; Kobayashi, M. Polymer 1991, 32, 1516-1526].