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PubMed2003

Scanning electron microscopy and atomic force microscopy imaging of solid lipid nanoparticles derived from amphiphilic cyclodextrins.

Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been applied to the imagery of solid lipid nanoparticles (SLNs) formulated from an amphiphilic cyclodextrin, 2,3-di-o-alkanoyl-beta-cyclodextrin, beta-CD21C6. Comparison of the results shows that the vacuum drying technique used in sample preparation for SEM causes shrinkage in the size of the SLNs, whereas the deposition method used for AFM causes the SLNs to form small clusters. The hydrodynamic diameter determined from photon correlation spectroscopy (PCS) is 359+/-15 nm and the zeta potential is -25 mV.

Cyclodextrins↗
PubMed1992

The acetic acid test in evaluation of subclinical genital papillomavirus infection: a comparative study on penoscopy, histopathology, virology and scanning electron microscopy findings.

OBJECTIVES: To evaluate colposcopic criteria in acetowhite lesions of the penis ("penoscopy") for the diagnosis of subclinical genitoanal papillomavirus infection (GPVI) compared with histopathological criteria of HPV involvement and to various hybridisation assays for HPV DNA detection, and to depict typical lesions by scanning electron microscopy. DESIGN: The study included 101 randomly selected male partners of females with known GPVI, or with penile symptoms such as itching, burning and dyspareunia who did not exhibit overt genital warts but appeared to be afflicted with acetowhite penile lesions after topical application of 5% acqueous acetic acid. Lesions were judged by penoscopy as either typical, conspicuous or nontypical for underlying HPV infection. Biopsy specimens from 91 men were examined by light microscopy and by either Southern blot (SB), polymerase chain reaction (PCR) and/or in situ hybridisation (ISH) assays for the presence of HPV DNA of the HPV types 6, 11, 16, 18, 31, 33 and 42 (Group A). From another ten men lesions clinically typical for GPVI were also examined topographically by scanning electronic microscopy (Group B). SETTING: The STD out-patient clinic of the Department of Dermatovenereology of Karolinska Hospital, Stockholm, Sweden. RESULTS: Group A Seventy eight (86%) of the biopsied lesions met the penoscopy criteria of being either typical of or conspicuous for GVPI. The agreement between penoscopy and histopathology was fairly good, as HPV diagnosis was made by both methods in 56 (62%) of the cases. The reliability of applying strict colposcopic hallmarks was further substantiated by the finding that 55 (60%) of the biopsy specimens taken from penoscopically typical/conspicuous lesions contained HPV DNA. However, there are diagnostic pitfalls for the acetic acid test. Coexistence of an eczematoid reaction with changes indicative of HPV influence was detected in six (7%) of the cases, while an inflammatory response only occurred in 17 (19%) of the specimens. Additional histopathological diagnoses (normal epithelium, lichen sclerosus et atrophicus, balanitis circinata parakeratotica, verruca plana) were established in another eight (9%) of the cases. Among the HPV DNA positive cases, all of the HPV types tested for were detected with the exception of HPV 18. A severe penile intraepithelial neoplasia (PIN III) was revealed in five (5%) of biopsies; HPV 16 was present in two and HPV 42 in one of these biopsy specimens. GROUP B: Scanning electron microscopy depiction harmonised with the penoscopy findings showing that subclinical GPVI characteristically exhibits a well demarcated, slightly elevated border and that the central area of lesions often displays a "groove" in which the epithelium appears to be thin with protrusions from beneath that probably represent capillaries. CONCLUSION: Use of the acetic acid test for evaluation of GPVI should be combined with a colposcopic evaluation based on strict topographic hallmarks, followed by a directed biopsy for light microscopic evaluation. We found that the positive predictive value of colposcopy was as high when correlated with histopathological findings (72%) as when virological methods were used, whether HPV DNA hybridisation testing was performed with the well established SB and ISH assays (45%), or by applying the newly introduced and highly sensitive PCR assay as well (71%). False positivity from the acetic acid test occurs and is mainly due to inflammatory conditions but also to the presence of other conditions. Epithelial fissures are evidently associated with some subclinical GPVI lesions and may potentially represent loci minores for infectious stimuli and perhaps facilitate the transmission of some blood-borne STDs. We prose that the term "papillomavirus balanoposthitis" should be used for penile HPV infection associated with inflammatory responses. Our study indicates that PIN III frequently occurs in a subclinical form and may be associated with not only previously identified "high-risk" HPV types such as type 16, but also with the HPV type 42 that has not previously been considered as oncogenic.

Acetates↗
PubMed1989

Kinetic analysis of thymocyte attachment to thymus stromal cells in culture by using phase-contrast and scanning electron microscopy.

Direct cellular contact between thymocytes and thymus stromal cells within the thymus appears to contribute to the maturation of thymocytes. Thymocyte-stromal cell complexes, formed in vivo, have been isolated by others and postulated to play a role in T-cell differentiation. These previous studies have been hampered, however, by a time-consuming isolation procedure from which only small numbers of these complexes are recovered. We have examined a model to study thymocyte-stromal cell complexes in vitro in which thymocytes are added to primary cultures of thymus stromal cells. In the present study, we found that thymocytes were histotypically selective in their attachment to thymus stromal cells. We also investigated the kinetics of thymocyte attachment to these thymus stromal cells. Cultures were examined at selected time intervals from 5 min through 3 days of incubation. Thymocyte attachment to stromal cells was a biphasic interaction, with maximum surface attachment at 15 min of cocultivation, followed by migration of thymocytes into the cultures. Morphological studies were confirmed by using 3H-leucine-labeled thymocytes and liquid scintigraphy. With increased time in culture, thymocytes became amoeboid and migrated between the layers of stromal cells where thymocyte mitotic figures were seen at 4 and 8 hr. In some cases it appeared that stromal cells, which often grew two to three cell layers deep, played an active role in enclosing thymocytes within the cultures. Large numbers of viable thymocytes were observed in the cultures at 24 hr. The number of thymocytes then decreased progressively on days 2 and 3, when relatively few were found within the layers of the culture.

Animals↗
PubMed2005

A comparative study of the structure of human and murine greater omentum.

In humans, the greater omentum is a fatty peritoneal fold that extends from the greater curvature of the stomach to cover most abdominal organs. It performs many functions, which include acting as a reservoir of resident peritoneal inflammatory cells, a storage site for lipid, and a regulator of fluid exchange in and out of the peritoneal cavity. Most importantly, the omentum readily adheres to areas of inflammation and peritoneal damage, often leading to adhesion formation. Despite its clinical importance, the omentum remains an understudied organ, and discrepancies exist as to its exact morphology. This study uses a combination of phase contrast microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to elucidate the structure of the greater omentum of both human and mouse and determine whether it possesses a typical surface mesothelial cell lining similar to other serosa. Results indicated that both human and murine omenta were of similar structure and composed of two distinct types of tissue, one adipose-rich and the other translucent and membranous. The adipose-rich regions were well-vascularised and covered by a continuous mesothelial cell layer except at the sites of milky spots. In contrast, translucent areas were poorly vascularised and contained numerous fenestrations of varying size. The possible function and developmental origin of these gaps is unclear; however, their role in promoting omental adhesion formation and in the successful use of omental graft material is discussed.

Adipose Tissue↗
PubMed2004

Light and scanning electron microscopy of the miracidium of Echinostoma paraensei (Trematoda, Echinostomatidae).

Echinostoma paraensei was described 1967 by Lie and Basch. Recently its natural definitive host, the aquatic rodent Nectomys squamipes, endemic in Brazil, was identified. As most of the echinostomatids, this species presents a zoonotic potential. The morphology and topography of the E. paraensei miracidium obtained from adult worms collected from the natural definitive host N. squamipes is described by light and electron microscopy. The arrangement and the dimensions of the epidermal plates are given. The eyespots are composed by two pairs of lenses measuring 6.03 microm. SEM observations shows that the miracidium body is covered by cilia except at the terebratorium region and the presence of alpha-tubulin in the cilia of the larvae is first recorded by immunelabeling. Nineteen papilla-like structures arranged in three axes and four groups were observed at the terebratoriun, this structure is retractable, presenting folds and a corrugated surface with profiles of cytoplasmic expansions, forming network of anatomizing folds.

Animals↗
PubMed2004

Mitosis in Giardia lamblia: multiple modes of cytokinesis.

Mitosis in Giardia is poorly understood. Until today, it is still controversial whether Giardia divides with a mirror-image symmetry (ventral-ventral or dorsal-dorsal) or in a dorsal-ventral mode. Here, we report the different modes by which cytokinesis takes place in Giardia lamblia. To determine how Giardia divides, video microscopy, scanning electron microscopy, semi-thick sections and freeze-fracture replicas were analyzed by transmission electron microscopy. Between 12 and 15% of the cells cultivated for 24-48 h were found in the process of division. Three types of cytokinesis were found: (1) ventral-ventral, where the discs face each other; (2) dorsal-dorsal, where the discs are in opposite directions; and (3) ventral-dorsal. Giardia divides with mirror-image symmetry either in ventral-ventral or dorsal-dorsal modes. During ventral-ventral type of division, Giardia becomes detached and swims freely in the culture medium, whereas, in the other modes of division, the cells can be found either adhered or swimming.

Animals↗
PubMed2005

Nectar-secreting floral stomata in Maxillaria anceps Ames & C. Schweinf. (Orchidaceae).

BACKGROUND AND AIMS: Although it was generally assumed that Maxillaria spp. do not produce nectar, in recent years, nectar has been reported for a number of these orchids. Nevertheless, our current understanding of nectary structure and nectar secretion in Maxillaria is based solely on M. coccinea (Jacq.) L.O. Williams ex Hodge, which, since it shows many features characteristic of ornithophilous flowers, is atypical of this largely entomophilous genus. The aim of the present paper is to describe, for the first time, nectar secretion in a presumed entomophilous species of Maxillaria. METHODS: The structure of the nectary of M. anceps Ames & C. Schweinf., nectar composition and the process of nectar secretion were investigated using light microscopy, scanning electron microscopy, transmission electron microscopy, histochemistry, refractometry and high performance liquid chromatography. KEY RESULTS AND CONCLUSIONS: Nectar appears as droplets that are exuded by modified stomata borne upon the labellar callus and collects upon the labellum and at the base of the column-foot. Although such stomata are known to occur in a number of angiosperm families, this is the first time for them to be observed in orchids. The callus consists largely of parenchyma with raphides and is supplied by eight to ten collateral bundles. This tissue, together with the single-layered epidermis, seemingly contains terpenoids. During the bud stage, the callus cells contain an organelle complement consistent with secretory cells whereas by day 4 of anthesis, much of the cell is occupied by a vacuole. The nectar is sucrose-dominant but also contains low concentrations of glucose, fructose, free amino acids and possibly terpenoids. The high sugar concentration (approx. 66 %) is consistent with melittophily and may indicate that, like the majority of Maxillaria spp., M. anceps is visited by stingless bees (Meliponini).

Chromatography, High Pressure Liquid↗