Comparative ultrastructure of the olfactory system in the East African root rat (Tachyoryctes splendens) and the naked mole rat (Heterocephalus glaber).

The ultrastructure of the olfactory system of most fossorial rodents remains largely unexplored. This study sought to investigate the functional structure of the olfactory mucosa and olfactory bulb of two species of fossorial rodents that have distinct behaviour and ecology, the East African root rat (RR) and the naked mole rat (NMR). Transmission electron microscopy and scanning electron microscopy were employed. The basic ultrastructural design of the olfactory system of the two species was largely comparable. In both species, the olfactory mucosa comprised an olfactory epithelium and an underlying lamina propria. The olfactory epithelium revealed olfactory knobs, cilia and microvilli apically and sustentancular cells, olfactory receptor neurons and basal cells in the upper, middle and basal zones, respectively. The lamina propria was constituted by Bowman's glands, olfactory nerve bundles and vasculature supported by loose connective tissue. Within the olfactory bulb, intracellular and extracellular structures including cell organelles, axons and dendrites were elucidated. Notable species differences were observed in the basal zone of the olfactory epithelium and on the luminal surface of the olfactory mucosa. The basal zone of the olfactory epithelium of the RR consisted of a single layer of flattened electron-dense horizontal basal cells while the NMR had juxtaposed electron-dense and electron-lucent heterogenous cells, an occurrence seen as being indicative of quiescent and highly proliferative states of the olfactory epithelia in the two species, respectively. The olfactory epithelial surface of the NMR comprised an elaborate cilia network that intertwined extensively forming loop-like structures whereas in the RR, the surface was rugged and consisted of finger-like processes and irregular masses. With gross and histological studies showing significant differences in the olfactory structures of the two species, these findings are a further manifestation that the olfactory system of the RR and the NMR have evolved differently to reflect their varied olfactory functional needs.

Functional Morphology of the Olfactory Mucosa and Olfactory Bulb in Fossorial Rodents: The East African Root Rat (Tachyoryctes splendens) and the Naked Mole Rat (Heterocephalus glaber).

Optimal functioning of the olfactory system is critical for survival of fossorial rodents in their subterranean lifestyle. This study examines the structure of the olfactory mucosa and olfactory bulb of two fossorial rodents exhibiting distinct social behaviors, the East African root rat and the naked mole rat. The social naked mole rat displayed simpler ethmoturbinates consisting of dorsomedial and broad discoid/flaplike parts that projected rostrally from the ethmoid bone. In the solitary root rat however, the ethmoturbinates were highly complex and exhibited elaborate branching which greatly increased the olfactory surface area. In addition, when correlated with the whole brain, the volume of the olfactory bulbs was greater in the root rat (4.24×10-2) than in the naked mole rat (3.92×10-2). Results of this study suggest that the olfactory system of the root rat is better specialized than that of the naked mole rat indicating a higher level of dependence on this system since it leads a solitary life. The naked mole rat to the contrary may have compensated for its relatively inferior olfactory system by living in groups in a social system. These findings demonstrate that structure of the olfactory system of fossorial mammals is dictated by both behavior and habitat.

Anti-proliferative activities of centella asiatica extracts on human respiratory epithelial cells in vitro / Actividades antiproliferativas del extracto de centella asiatica sobre células epiteliales respiratorias humanas in vitro

Centella asiatica or "pegaga" is well known for its ability in promoting wound healing. This study focused on the effect of Centella asiatica on the proliferation of human respiratory epithelial (RE) cells. RE cells were cultured using co-culture techniques until first passage (P1). Viability cell test by tryphan blue dye exclusion assay showed that there was high percentage of cell viability at both P0 (74 percent) and P1 (91.61 percent). Triplicate MTT assays were carried out with different concentrations of C. asiatica from 15.6 ppm, 31.3 ppm, 62.5 ppm, 125 ppm, 250 ppm, 500 ppm, 1000 ppm, until 2000 ppm. The higher the concentration of C. asiatica, the more inhibitory effect was seen. C. asiatica aqueous extract at concentration 1000 ppm and 2000 ppm demonstrated a significant (p<0.05) inhibitory effect on human RE cells proliferation on day 4 and day 7 after treatment. This provides potential use of C. asiatica extract for the treatment of conditions with respiratory epithelial cells overgrowth.

La Centella asiatica o "pegaga" es conocida por su capacidad para promover la cicatrización de heridas. Este estudio se centró en el efecto de la Centella asiatica sobre la proliferación de las células del epitelio respiratorio (ER) humano. Las células del ER se cultivaron usando técnicas de co-cultivo hasta el primer paso (P1). La prueba la viabilidad celular mediante el ensayo de exclusión del colorante azul de tripano demostró un alto porcentaje de viabilidad celular tanto en P0 (74 por ciento) y P1 (91,61 por ciento). Ensayos de MTT por triplicado se llevaron a cabo con diferentes concentraciones de C. asiatica, desde 15,6 ppm, 31,3 ppm, 62,5 ppm, 125 ppm, 250 ppm, 500 ppm, 1000 ppm, hasta 2000 ppm. Con una mayor concentración de C. asiatica, se observó un mayor efecto inhibitorio. El extracto acuoso de C. asiatica a una concentración de 1000 ppm y 2000 ppm demostró un efecto inhibidor significativo (p<0,05) sobre la proliferación de células del ER humano los días 4 y 7 posterior al tratamiento. Esto proporciona el uso potencial del extracto de C. asiatica para el tratamiento de condiciones con crecimiento excesivo células epiteliales respiratorias.

Anticancer drug vinblastine sulphate induces transient morphological changes on the olfactory mucosa of the rabbit.

Vinblastine sulphate (VBS) is an anticancer drug that acts by disrupting microtubule dynamics of highly mitotic tissue cells. The consequences of VBS on the olfactory mucosa (OM), a tissue with high mitotic numbers, are not clearly understood. We used qualitative and quantitative methods to determine the structural changes that may be produced on the rabbit OM by VBS. Following a single dose (0.31 mg/kg) of this drug, the structure of the mucosa was greatly altered on the first 3-5 days. The alteration was characterized by disarrangement of the normal layering of nuclei of the epithelia, degeneration of axonal bundles, occurrence of blood vessels within the bundles, localized death of cells of Bowman's glands and glandular degeneration. Surprisingly on or after day 7 and progressively to day 15 post-exposure, the OM was observed to regenerate and acquire normal morphology, and the vessels disappeared from the bundles. Relative to control values, bundle diameters, olfactory cell densities and cilia numbers decreased to as low as 53.1, 75.2 and 71.4%, respectively, on day 5. Volume density for the bundles, which was 28.6% in controls, decreased to a lowest value of 16.8% on day 5. In contrast, the volume density for the blood vessels was significantly lower in controls (19.9%) than in treated animals at day 2 (25.8%), day 3 (34.3%) and day 5 (31.5%). These findings suggest that the changes induced on the rabbit OM by VBS are transient and that regenerative recovery leads to the restoration of the normal structure of the mucosa.

Comparative Quantitative and Qualitative Attributes of the Surface Respiratory Macrophages in the Domestic Duck and the Rabbit / Atributos Cualitativos, Cuantitativos y Comparativos de los Macrófagos de la Superficie Respiratoria en el Pato Doméstico y el Conejo

In mammals, surface respiratory macrophages (SM) are known to play a foremost role in protecting the respiratory system by providing first line of defense through engulfing pathogens and particulate matter respired with air. It has been reported that the pulmonary cellular defense system of domestic birds is inadequate. In particular, low number of SM and even lack of the cells in a healthy avian respiratory system have been associated with susceptibility of domestic birds to respiratory diseases. In an endeavor to resolve the existing controversy, the quantitative and qualitative attributes of the surface respiratory macrophages of the domestic duck and of the domestic rabbit were compared under similar experimental conditions. Quantitatively, the rabbit SM were on average approximately fourteen times more than the duck SM. The SM were found to have comparable diameters measuring about 12 µm in the duck and 13 µm in the rabbit. Similarly, the duck and the rabbit SM were structurally similar. Typically, they were round granular cells possessing filopodial extensions and variable electron dense bodies in the cytoplasm. The phagocytic capacity measured using polystyrene particles revealed that the duck SM had a higher phagocytic capacity than the rabbit SM. The volume density of the engulfed polystyrene particles, i.e. the volume of the particles per unit volume of the cell was estimated at 20 percent in the duck and 9 percent in the rabbit. These results suggest that the comparatively low numbers of SM in domestic birds may contribute to susceptibility of the birds to diseases. However, given the high phagocytic capacity of the avian SM, susceptibility of the domestic birds may not be due to dearth of the SM alone but some other factor (s) such as persistent exposure of the birds to particulate matter which is known to reduce robustness of the SM may be involved.

En los mamíferos, los macrófagos de la superficie respiratoria (SM) son conocidos por jugar el papel más importante en la protección del sistema respiratorio, proporcionando la primera línea de defensa en contra de agentes patógenos y envolviendo las partículas de aire respirado. Se ha informado que el sistema de defensa celular pulmonar de las aves domésticas es insuficiente. En particular, el bajo número de SM, e incluso las células del sistema respiratorio de las aves domésticas, en un ambiente sano, se ha asociado con susceptibilidad a enfermedades respiratorias. En un esfuerzo para resolver la controversia existente, los atributos cuantitativos y cualitativos de los macrófagos de la superficie respiratoria del pato doméstico y el conejo doméstico fueron comparados en las mismas condiciones experimentales. Cuantitativamente, los SM del conejo fueron en promedio aproximadamente catorce veces más que los SM en el pato. Los SM se encontraron con un diámetro comparable, al medir alrededor de 12 micras en el pato y 13 micras en el conejo. Del mismo modo, en el pato y el conejo los SM eran estructuralmente similares. Por lo general, correspondieron a células granulares con extensiones filopodiales y organismos electrodensos variables en el citoplasma. La capacidad fagocítica medida utilizando partículas de poliestireno reveló que los SM del pato tenían una mayor capacidad fagocítica que el conejo. La densidad de volumen de las partículas de poliestireno envueltas, es decir, el volumen de las partículas por unidad de volumen se estimó en 20 por ciento en el pato y 9 por ciento en el conejo. Estos resultados sugieren que el número comparativamente bajo de los SM en las aves domésticas puede contribuir a su susceptibilidad a enfermedades. Sin embargo, dada la alta capacidad fagocítica de los SM aviares, la susceptibilidad de las aves domésticas no puede deberse solamente a la escasez de SM, sino a algunos otros factores pueden estar involucrados, como la exposición persistente de las aves a partículas, las cuales se sabe reducen la robustez de los SM.

Structural organisation of tunica intima in the aorta of the goat.

The structural organisation of tunica intima in the aorta is important for its integrity, prediction, and diagnosis of atherosclerosis. The goat is a suitable model for cardiovascular studies, but the structure of its tunica intima is scarcely reported. This study, therefore, aimed to describe features of the goat aortic tunica intima by light and transmission electron microscopy. Sixteen healthy male domestic goats (capra hircus) aged between 6 and 24 months were used: 8 for light and 8 for electron microscopy. The animals were euthanised with sodium pentabarbitone 20 mg/mL and fixed with 3% phosphate buffered glutaraldehyde. For light microscopy, specimens from various regions of the aorta were routinely processed for paraffin embedding and 7 mm sections stained with Mason's trichrome. Those for transmission electron microscopy were post fixed in osmium tetroxide, embedded in Durcupan, and ultrathin sections stained with uranyl acetate and counter stained with lead citrate. Endothelium comprises round and squamous cells, linked to the subendothelial material by a simple and sometimes lamellated basement membrane. In the subendothelial zone, a heterogenous population of cells are connected with interlinked collagen and elastic fibres. Both cells and fibres are connected to the internal elastic lamina. The composite structure and interlinkages in the tunica intima permit unitary function and increase mechanical strength, thus enabling it to withstand haemodynamic stress.

Regional differences in aorta of goat (capra hircus).

Regional differences in the aortic wall are important in explaining the physicomechanical properties and disease distribution in this artery. The goat is a suitable model for studying cardiovascular disease, but the regional features of its aorta are scarcely reported. The purpose of the study was therefore to describe the regional differences in the wall of its aorta. Sixteen healthy adult male domestic goats (capra hircus) were euthanised with intravenous sodium pentabarbitone and specimens obtained from the ascending, arch, each vertebral level of descending thoracic, and various segments of abdominal aorta. The specimens were fixed in 10% formaldehyde solution and routinely processed for paraffin embedding. Seven micron thick sections were stained with Mason's Trichrome and Weigert Resorcin Fuchsin stains. Light microscopic examination revealed that the aortic wall consists of tunica intima comprising endothelium, subendothelial zone and internal elastic lamina, media, and adventitia. Endothelium comprises flat and round endotheliocytes. The population of round cells declines as the internal elastic lamina increases in prominence caudally. Tunica media in ascending, arch, and proximal thoracic aorta comprises two zones: namely a luminal elastic and adventitial musculo-elastic zone, in which muscle islands interrupt some elastic lamellae. These islands progressively diminish caudally until by the eleventh thoracic vertebra they are only patchy. Beyond this point and in the abdominal aorta they are absent and tunica media consists of regular concentric elastic lamellae. Tunica adventitia, on the other hand, increases in thickness and elastic fibre content caudally. Regional variations exist in all three layers of goat aorta. The nature of these differences suggests that they are related to haemodynamic factors. Furthermore, the variations may form the basis for regional differences in physicomechanical strength and disease distribution along the aorta.

Recent advances into understanding some aspects of the structure and function of mammalian and avian lungs.

Recent findings are reported about certain aspects of the structure and function of the mammalian and avian lungs that include (a) the architecture of the air capillaries (ACs) and the blood capillaries (BCs); (b) the pulmonary blood capillary circulatory dynamics; (c) the adaptive molecular, cellular, biochemical, compositional, and developmental characteristics of the surfactant system; (d) the mechanisms of the translocation of fine and ultrafine particles across the airway epithelial barrier; and (e) the particle-cell interactions in the pulmonary airways. In the lung of the Muscovy duck Cairina moschata, at least, the ACs are rotund structures that are interconnected by narrow cylindrical sections, while the BCs comprise segments that are almost as long as they are wide. In contrast to the mammalian pulmonary BCs, which are highly compliant, those of birds practically behave like rigid tubes. Diving pressure has been a very powerful directional selection force that has influenced phenotypic changes in surfactant composition and function in lungs of marine mammals. After nanosized particulates are deposited on the respiratory tract of healthy human subjects, some reach organs such as the brain with potentially serious health implications. Finally, in the mammalian lung, dendritic cells of the pulmonary airways are powerful agents in engulfing deposited particles, and in birds, macrophages and erythrocytes are ardent phagocytizing cellular agents. The morphology of the lung that allows it to perform different functions-including gas exchange, ventilation of the lung by being compliant, defense, and secretion of important pharmacological factors-is reflected in its "compromise design."

Traditional antimalarial phytotherapy remedies used by the South Coast community, Kenya.

AIM OF THE STUDY: This study was conducted to document herbal medicines used in the treatment of malaria as well as the existing knowledge, attitudes and practices related to malaria recognition, control and treatment in South Coast, Kenya. METHODS: Data was collected using semistructured questionnaires and interviews. A focused group discussion held with the community members, one in each of the study villages supplemented the interview and questionnaire survey. RESULTS: The respondents were found to have a good understanding of malaria and could distinguish it from other fever types. They were also aware that malaria was spread by mosquitoes. Malaria prevalence was high, and affected individuals an average of four times a year. Community members avoided mosquito bites by using mosquito nets, clearing bushes around their homesteads and burning plant parts to generate smoke. They prevented and treated malaria by taking decoctions or concoctions of traditional herbal remedies. Forty plant species in thirty-five genera distributed in twenty-four families were used as antimalarials in the study area. Five plant species, namely; Heeria insignis Del. (Anacardiaceae), Rottboelia exaltata L.F (Gramineae), Pentanisia ouranogyne S. Moore (Rubiaceae), Agathisanthenum globosum (A. Rich) Hiern (Rubiaceae), and Grewia trichocarpa Hochst ex A. Rich (Tiliaceae) are documented for the first time in South Coast, Kenya, for the treatment of malaria. CONCLUSIONS: The plants documented in the current study are a potential source for new bioactive compounds of therapeutic value in malaria treatment. The results provide data for further pharmacological and toxicological studies and development of commercial antimalarial phytotherapy products.

Effects of opioids in the formalin test in the Speke's hinged tortoise (Kinixy's spekii).

Little is known about analgesia in lower vertebrates such as the Speke's hinged tortoise (Kinixy's spekii), yet of late they are increasingly being adopted as pets. The effects of morphine (5, 7.5, 10 and 20 mg/kg), pethidine (10, 20, and 50 mg/kg) and naloxone (5 mg/kg) on nociception induced by the formalin test (12.5%, 100 microL) were studied in the Speke's hinged tortoise. Formalin induced a monophasic limb retraction behavioural response and its duration was recorded. The behaviour lasted for 16.4 +/- 0.8 min. Morphine (7.5, 10 and 20 mg/kg) and pethidine (20 and 50 mg/kg) induced significant decrease in the duration of limb retraction in the formalin test. The anti-nociceptive effects were naloxone (5 mg/kg) reversible. The data suggest that the formalin test is a good test for studying nociception and anti-nociception in tortoises and that the opioidergic system plays a role in the control of nociception in these animals.

Antimalarial herbal remedies of Msambweni, Kenya.

Malaria is a serious cause of mortality globally. The disease is of regional concern in Africa and of national interest in Kenya due to its high morbidity and mortality as a result of development of resistant strains of Plasmodium falciparum to many existing drugs such as chloroquine. Alternative medicine using herbal remedies are commonly used to treat malaria in Kenya. However, plants used in some rural areas in Kenya are not documented. Many antimalarial drugs have been derived from plants. This study was conducted to document medicinal plants that are traditionally used by the Msambweni community of Kenyan South Coast to treat malaria, where the disease is endemic. Herbalists were interviewed by administration of semistructured questionnaires in order to obtain information on medicinal plants traditionally used for the treatment of malaria. Focused group discussions held with the herbalists supplemented the interview and questionnaire survey. Twenty-seven species of plants in 24 genera distributed in 20 families were reported to be used in this region for the treatment of malaria. Labiatae, Rutaceae and Liliaceae families had each eleven percent of the plant species reported and represented the species that are most commonly used. Thirteen plant species, namely; Aloe deserti Berger (Liliaceae), Launea cornuta (Oliv and Hiern) C. Jeffrey (Compositae), Ocimum bacilicum L. (Labiatae), Teclea simplicifolia (Eng) Verdoon (Rutaceae), Gerranthus lobatus (Cogn.) Jeffrey (Cucurbitaceae), Grewia hexaminta Burret. (Tiliaceae), Canthium glaucum Hiern. (Rubiaceae), Amaranthus hybridus L. (Amaranthaceae), Combretum padoides Engl and Diels. (Combretaceae), Senecio syringitolius O. Hoffman. (Compositae), Ocimum suave Willd (Labiatae), Aloe macrosiphon Bak. (Liliaceae) and Laudolphia buchananii (Hall.f) Stapf. (Apocynaceae) are documented from this region for the first time for the treatment of malaria. These results become a basis for selection of plants for further pharmacological, toxicological and phytochemical studies in developing new plant based antimalarial drugs.

Comparative in vitro study of interactions between particles and respiratory surface macrophages, erythrocytes, and epithelial cells of the chicken and the rat.

In mammals, surface macrophages (SMs) play a foremost role in protecting the respiratory system by engulfing and destroying inhaled pathogens and harmful particulates. However, in birds, the direct defense role(s) that SMs perform remains ambiguous. Paucity and even lack of SMs have been reported in the avian respiratory system. It has been speculated that the pulmonary defenses in birds are inadequate and that birds are exceptionally susceptible to pulmonary diseases. In an endeavour to resolve the existing controversy, the phagocytic capacities of the respiratory SMs of the domestic fowl and the rat were compared under similar experimental conditions by exposure to polystyrene particles. In cells of equivalent diameters (8.5 microm in the chicken and 9.0 microm in the rat) and hence volumes, with the volume density of the engulfed polystyrene particles, i.e. the volume of the particles per unit volume of the cell (SM) of 23% in the chicken and 5% in the rat cells, the avian cells engulfed substantially more particles. Furthermore, the avian SMs phagocytized the particles more efficiently, i.e. at a faster rate. The chicken erythrocytes and the epithelial cells of the airways showed noteworthy phagocytic activity. In contrast to the rat cells that did not, 22% of the chicken erythrocytes phagocytized one to six particles. In birds, the phagocytic efficiencies of the SMs, erythrocytes, and epithelial cells may consolidate pulmonary defense. The assorted cellular defenses may explain how and why scarcity of SMs may not directly lead to a weak pulmonary defense. The perceived susceptibility of birds to respiratory diseases may stem from the human interventions that have included extreme genetic manipulation and intensive management for maximum productivity. The stress involved and the structural-functional disequilibria that have occurred from a 'directed evolutionary process', rather than weak immunological and cellular immunity, may explain the alleged vulnerability of the avian gas exchanger to diseases.

The morphology of the pecten oculi of the ostrich, Struthio camelus.

The pecten oculi is a structure peculiar to the avian eye. Three morphological types of pecten oculi are recognized: conical type, vaned type and pleated type. The pleated type has been well studied. However, there exists only scanty data on the morphology of the latter two types of pectens. The structure of the vaned type of pecten of the ostrich, Struthio camelus was investigated with light and electron microscope. The pecten of this species consists of a vertical primary lamella that arises from the optic disc and supports 16-19 laterally located secondary lamellae, which run from the base and confluence at the apex. Some of the secondary lamellae give rise to 2 or 3 tertiary lamellae. The lamellae provide a wide surface, which supports 2-3 Layers of blood capillaries. Pigmentation is highest at the distal ends of the secondary and tertiary Lamella where blood capillaries are concentrated and very scanty on the primary and the proximal ends of the secondary lamella where the presence of capillaries is much reduced. In contrast to the capillaries of the pleated pecten, the endothelium of the capillaries in the pecten of the ostrich exhibits very few microvilli. These observations suggest that the morphology of the pecten of the ostrich, a flightless ratite bird is unique to the pleated pecten and is designed to meet the balance between optimal vision and large surface area for blood supply and yet ensuring it is kept firmly erect within the vitreous.

Evaluation of phagocytic activity in human monocyte-derived dendritic cells.

Dendritic cells play a central role in initiation of primary T lymphocyte responses to foreign antigens. Their potency in antigen presentation vis-à-vis reported low or lack of ability to phagocytize particulate matter has limited our understanding of the role that they play in inducing immunity to particulate antigens. One hypothesis is that dendritic cells may possess a high phagocytic capacity when immature and located in peripheral tissues, which they lose on maturation. Our goal was to characterize the phagocytic capacity in human immature dendritic cells. The phagocytic capacity of human monocyte-derived immature dendritic cells was studied by morphological and morphometric means, and compared to that of professional phagocytes, human alveolar macrophages, their progenitors, the peripheral blood monocytes, and mature dendritic cells. Phagocytic index (proportion of phagocytic cells) was decreased by 42.8% (immature dendritic cells) and 74.2% (mature dendritic cells) with respect to monocytes. Similarly, the phagocytic index was decreased by 46.5% (immature dendritic cells) and 75.9% (mature dendritic cells) with respect to macrophages. Volume density of phagocytized particles was decreased by 76.1% (immature dendritic cells) and 96.7% (mature dendritic cells) with respect to the monocytes. However, volume density was decreased by 34.3% (immature dendritic cells) and 91% (mature dendritic cells) with respect to alveolar macrophages. These results show that human monocyte-derived immature dendritic cells possess a phagocytic capacity that is lower than that of peripheral blood monocytes and alveolar macrophages but higher than that of mature dendritic cells.

Hydrophilic poly(DL-lactide-co-glycolide) microspheres for the delivery of DNA to human-derived macrophages and dendritic cells.

Biodegradable poly(lactide-co-glycolide) (PLGA) microspheres have a proven track record for drug delivery and are suggested to be ideal carrier systems to target therapeutics into phagocytic cells such as macrophages (MPhis) and dendritic cells (DCs). Microspheres prepared by spray-drying from different PLGA-type polymers were evaluated regarding their effect on phagocytosis, intracellular degradation and viability of human-derived macrophages MPhis and DCs. Even the microspheres prepared from the most hydrophilic polymer RG502H, were efficiently phagocytosed by primary human MPhis and DCs. Interestingly, uptake of PLGA microspheres by DCs as potent immune modulator cells was almost as efficient as uptake by the highly phagocytic MPhis. Phagocytosed microspheres remained inside the cells until decay with none of the microsphere preparations induced significant apoptosis or necrotic cell death. Acidic pH and the phagosomal environment inside the cells enhanced microsphere decay and release of encapsulated material. Degradation of microspheres consisting of the most hydrophilic PLGA polymer RG502H occurred in a reasonable time frame of less than 2 weeks ensuring the release of encapsulated drug during the life span of the cells. To explore important technical and biological aspects of DNA microencapsulation, we have studied DNA loading and in vitro DNA release of microspheres from different PLGA type polymers. Hydrophobicity and molecular weight of the PLGA polymers had profound influence on both the encapsulation efficiency of DNA and its release kinetics in vitro: the hydrophilic polymers showed higher encapsulation efficiency and faster release of intact DNA compared to the hydrophobic ones. These results suggest that microspheres from the PLGA polymer RG502H have improved characteristics for DNA delivery to human MPhis and DCs.

Genetic background of attenuated Salmonella typhimurium has profound influence on infection and cytokine patterns in human dendritic cells.

Salmonella typhimurium (ST) can cause infection in man, and attenuated strains are under consideration as live vaccine vectors. However, little is known about the interaction of ST with human dendritic cells (DC). Here, we compared the consequences of exposure of human, monocyte-derived DC with different attenuated strains of ST. Infection was observed with all four strains tested (wild type, PhoP-, PhoPc, and AroA), but the PhoPc strain was by far the most efficient. Intracellular persistence of wild type and PhoP- was longer than that of PhoPc and AroA, both of which were largely eliminated within 24 h. Most DC survived infection by the attenuated strains, although apoptosis was observed in a fraction of the exposed cells. All strains induced DC maturation, independent from the extent of infection. Although all strains stimulated secretion of TNF-alpha and IL-12 strongly, PhoPc induced significantly less IL-10 than the other three strains and as much as 10 times less IL-10 than heat-killed PhoPc, suggesting that this mutant suppressed the secretion of IL-10 by the DC. These data indicate that infectivity, bacterial elimination, and cytokine secretion in human DC are controlled by the genetic background of ST.

A scanning electron microscope study of the luminal surface specializations in the blood vessels of the pecten oculi in a diurnal bird, the black kite (Milvus migrans).

The luminal surface of the pecten oculi of the black kite (Milvus migrans), a diurnally active bird of prey, was examined by scanning electron microscopy. In this species the blood vessels are generally of two types, the small-calibre capillaries and the large-calibre afferent and efferent vessels. The luminal surface of the efferent blood vessels possesses a few low microplicae. Conversely, the luminal surface of the afferent blood vessels is characteristically smooth except at the cell junctions and at the point of entry into the capillaries. The cells junctions are marked by low ragged ridges while the luminal surface is studded with low sparse pleiomorphic microprojections at the point of capillary emergence. The luminal surface of the blood capillaries is characterised by a labyrinth of closely disposed microplicae that projects into the lumen. These microplicae show no particular orientation with respect to either the longitudinal or transverse axis of the capillary. Instead, they are diffusely orientated. It is conjectured that such a heterogeneous design of the endothelium in the blood vessels of the pecten oculi has developed in order to augment the role of the pecten in the transport of nutrients to the avascular neural retina by an energy saving diffusion process. The process through which the design of the microfolds affects haemodynamics and their putatite role in facilitating the delivery of nutrients are discussed in the perspective of the available data.

Surface specialization of the capillary endothelium in the pecten oculi of the chicken, and their overt roles in pectineal haemodynamics and nutrient transfer to the inner neural retina.

The structure of the capillary endothelium in the pecten oculi of the domestic fowl was investigated by scanning and transmission electron microscopy. Scanning electron microscopy results demonstrated the existence of a vast array of irregular microplicae that projected from the luminal surface of the capillary endothelium. In between these microplicae were numerous crevices. The microplicae were closely packed and showed no preferred orientation regarding either the longitudinal or transverse plane of the capillaries. Transmission electron microscopy revealed the section profiles of the microplicae: their tortuity, branching, interdigitations and the magnitude of the crevices contained. The endothelial cytoplasm exhibited a few mitochondria and micropinocytotic vesicles. The apparent set-up of the luminal plasmalemmal infoldings seemed to be designed for effecting impedance to the pectineal blood flow and thereby facilitating passive permeation of blood-borne nutrients to the inner neural retina. The reasons of such passive transport operation mediated by the endothelial microplicae of the avian pecten oculi are discussed in the perspective of the existing literature.

A scanning electron microscope study of the pecten oculi of the black kite (Milvus migrans): possible involvement of melanosomes in protecting the pecten against damage by ultraviolet light.

The pecten oculi of the black kite (Milvus migrans), a diurnally active bird of prey, has been examined by scanning electron microscopy. In this species the pecten consists of 12 highly vascularised pleats, held together apically by a heavily pigmented 'bridge' and projects freely into the vitreous body in the ventral part of the eye cup. Ascending and descending blood vessels of varying calibre, together with a profuse network of capillaries, essentially constitute the vascular framework of the pecten. A distinct distribution of melanosomes is discernible on the pecten, the concentration being highest at its apical end, moderate at the crest of the pleats and least at the basal and lateral margins. Overlying and within the vascular network, a close association between blood vessels and melanocytes is evident. It is conjectured that such an association may have evolved to augment the structural reinforcement of this nutritive organ in order to keep it firmly erectile within the gel-like vitreous. Such erectility may be an essential prerequisite for its optimal functioning, as well as in its overt use as a protective shield against the effects of ultraviolet light, which otherwise might lead to damage of the pectineal vessels.