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At least 775 records · Page 43Linked to original sources
PubMed1997

Horseradish peroxidase: a reliable or a misleading tool for the investigations on the origin of the proteins of the aqueous humor?

The concept of the blood-aqueous barrier is largely based on the use of horseradish peroxidase (HRP). The present investigation was designed to check its reliability as a macromolecular tracer, especially with regard to the transport of plasma proteins. Rabbits were killed 5 min to 24 h after being intravenously injected with HRP. The tracer diffused rapidly, reaching the aqueous humor of the eye in 3 min or less and was detected at high concentration in the narrow space between the outer epithelial layer of the ciliary epithelium and the wall of the pervious capillaries in the stroma of the processes. HRP appeared to migrate from the blood to the posterior chamber, permeating the tight junctions, viz., the anatomical basis of the blood-aqueous barrier. It was detected at higher concentration at the anterior surface of the iris, at short time intervals; this was interpreted as penetration of the tracer from the aqueous humor of the anterior chamber. The choroid was also labeled in continuation with the reaction in the stroma of the pars plana of the ciliary body which, in turn, sometimes reached the iris root. Therefore, the pervious blood vessels of the choroid could be a source of macromolecules for the iris root. HRP also induced the formation of lysosomes in the ciliary epithelium. This can hardly be accepted as the way in which plasma proteins are physiologically transported to the aqueous humor. However, the pathway of HRP migration over short time intervals seems to be in agreement with previous research indicating that the entrance of serum albumin into the posterior chamber is the first step of its incorporation into the aqueous humor.

Acid Anhydride Hydrolases↗
PubMed1997

Internalization and recycling of vitellogenin receptor in the mosquito oocyte.

The major yolk protein precursor in mosquito oocytes, vitellogenin (Vg), is internalized by a 205-kDa membrane-bound receptor (VgR). Recently, VgR has been isolated permitting the production of polyclonal anti-VgR antibodies. To elucidate the pathway of VgR internalization and recycling in mosquito oocytes during Vg uptake, we carried out an immunogold electron-microscopic study, labeling both Vg and VgR in ultrathin frozen sections of ovarian tissue. VgR immunolabeling demonstrated that the oocyte plasma membrane was subdivided into microdomains, with VgR being located between and at the lower portions of the oocyte microvilli. During the early stages of internalization, Vg and VgR were observed together in coated pits, coated vesicles, and early endosomes. Fusion of early endosomes created transitional yolk bodies (TYB) in which Vg and VgR became segregated. VgR label was present in the numerous tubular compartments that protruded from the TYBs. These tubular organelles extended to and fused with the plasma membrane, suggesting that they represented the vehicle for VgR recycling. Vg label was not observed in the tubular compartments. Instead, Vg accumulated in the core of the TYB, a region free of VgR label. Mature yolk bodies (MYB) were heavily labeled for Vg, but completely lacked any VgR label, indicating that MYB are storage compartments that do not participate in receptor recycling. Thus, our immunocytochemical data clearly visualize the steps in Vg/VgR internalization, dissociation, sorting, and recycling of the receptor to the plasma membrane.

Aedes↗
PubMed1997

Partial characterization of a new virus from ranunculus with a divided RNA genome and circular supercoiled thread-like particles.

An undescribed virus, here named ranunculus white mottle virus, was isolated in Italy from cultivated ranunculus showing mottle and distortion of leaves. The virus was mechanically transmissible to several herbaceous hosts. In negative stain, the particles appeared as circularised supercoiled threads 3 nm in diameter of different contour lengths; in some conditions the circles collapsed to form linear pseudobranched structures 9 nm in diameter. Immunolabeling of thin sections showed that viral antigen was widely distributed in the cytoplasm of parenchyma cells. The virus was not serologically related to the morphologically similar tenuiviruses, citrus psorosis-ringspot virus and tulip mild mottle mosaic virus. A major 43 kDa protein was present in purified preparations and in infected plant tissue, as also was a minor 28 kDa protein, serologically related to the major one. Nucleic acids extracted from purified particles consisted of at least three RNAs, of approximately 7.5, 1.8 and 1.5 kb, which appeared partly in single- and partly in double-stranded form. Purified preparations, but not viral RNAs, when mechanically inoculated, were infectious. Host range, tissue tropism, particle morphology and coat protein size place the virus closest to citrus psorosis-ringspot and tulip mild mottle mosaic viruses. These three viruses in turn show similarities with the Tenuiviruses and Bunyaviridae.

Capsid↗
PubMed2006

Taurine release in mouse brain stem slices under cell-damaging conditions.

Taurine has been thought to be essential for the development and survival of neural cells and to protect them under cell-damaging conditions. In the brain stem taurine regulates many vital functions, including cardiovascular control and arterial blood pressure. We have recently characterized the release of taurine in the adult and developing brain stem under normal conditions. Now we studied the properties of preloaded [3H]taurine release under various cell-damaging conditions (hypoxia, hypoglycemia, ischemia, the presence of metabolic poisons and free radicals) in slices prepared from the mouse brain stem from developing (7-day-old) and young adult (3-month-old) mice, using a superfusion system. Taurine release was greatly enhanced under these cell-damaging conditions, the only exception being the presence of free radicals in both age groups. The ischemia-induced release was characterized to consist of both Ca2+-dependent and -independent components. Moreover, the release was mediated by Na+-, Cl--dependent transporters operating outwards, particularly in the immature brain stem. Cl- channel antagonists reduced the release at both ages, indicating that a part of the release occurs through ion channels, and protein kinase C appeared to be involved. The release was also modulated by cyclic GMP second messenger systems, since inhibitors of soluble guanylyl cyclase and phosphodiesterases suppressed ischemic taurine release. The inhibition of phospholipases also reduced taurine release at both ages. This ischemia-induced taurine release could constitute an important mechanism against excitotoxicity, protecting the brain stem under cell-damaging conditions.

2,4-Dinitrophenol↗
PubMed2002

Microleakage in class II composite resin restorations: application of a clearing protocol.

Microleakage at the cervical tooth/restoration interface of class II restorations was evaluated, either on multiple sections or on teeth rendered transparent, in order to determine whether a modified clearing protocol could be established as a routine method for microleakage evaluation in class II restorations. Forty-eight class II cavities were restored with a composite/bonding agent (Tetric Universal/Heliobond, Vivadent, Schaan, Liechtenstein) in bulk technique (BT) (n=24) and with a composite/dentin adhesive system (Tetric Universal/Heliobond/Syntac Classic) in increments (IT) (n=24). The 24 specimens were assigned to two groups. Group I: dye penetration (India ink), multiple sectioning (conventional method). Group II: dye penetration (India ink) and modified clearing protocol. Linear microleakage (% dye/section) along the cervical tooth/restoration interface on multiple sections, and microleakage patterns (% dye/surface) at the cervical surface on transparent teeth were evaluated with an image analyzing system. The data were statistically analyzed with the Mann Whitney U-test, Wilcoxon's rank sum test, and the error rates method. The application of the modified clearing protocol allowed for distinct evaluation of microleakage patterns. Either protocol revealed lower penetration values for IT than for BT. With the conventional protocol, the median (25-75% percentiles) percentage of dye penetration was 2% (1-46%) for IT and 40% (23-85%) for BT. The clearing protocol revealed dye penetration of 5% (1-22%) for IT and 16% (4-24%) for BT. The clearing protocol together with the use of India ink as tracer allows for evaluation and visualization of the continuous distribution of microleakage at the cervical tooth/restoration interface without loss of information due to sectioning, although this method seems to be less discriminative than the conventional sectioning technique.

Acrylates↗
PubMed2003

Use of oolong tea extract (OTE) for elastin staining and enhancement in ultrathin sections.

To assess the usefulness of oolong tea extract (OTE) staining for connective tissue observation, we examined the visceral pleural mesothelium of rat lung by transmission electron microscope. Four kinds of electron microscopic staining methods (routine, tannic acid, OTE in distilled water, and OTE in 0.1 M phosphate buffer) were compared to determine the most suitable method for electron microscopic observation of ultrathin sections. Elastin (elastic laminae) was selectively stained by tannic acid and both water and buffered OTE. Except for elastin, connective tissue and cell ultrastructures were also electron enhanced by tannic acid and both water and buffered OTE staining. However, using water OTE, the electron-dense filaments (10-12 nm in diameter) were obscured. In tannic acid staining, the unit membranes of the visceral pleural mesothelial cells were weaker as compared with routine and buffered OTE stains. Thus, the buffered OTE staining method is a highly useful technique for connective tissue observation and electron-enhanced staining in transmission electron microscopic preparations.

Animals↗
PubMed2006

Antigenic profile of osteoblasts present in human bone tissue sections.

The antigenic profile of human osteoblasts was previously analyzed by our group using primary cultures as study samples. These studies suggested a novel functional approach to this cell population. Osteoblasts have a characteristic antigenic profile and share antigens in common with other cell populations that also originate in the bone marrow. Some of the detected antigens are constitutively expressed, while others are modulated by different factors and/or cytokines. The aim of the present study was to analyze the antigens present in osteoblasts in vivo, since the presence of certain biomolecules in fetal bovine serum may modulate the antigenic expression, compromising the results. For this purpose, human bone tissue sections were analyzed with a wide panel of mAbs and using the immunoperoxidase technique. CD10, CD44 and alkaline phosphatase antigens and IL-12, IL-18 and IFNgamma cytokines were detected in osteoblasts in the bone tissue. However, CD80 and HLA-DR antigens were not found in all samples and when present their expression was weak. The expression of CD54 antigen was moderate or weak. These results allow data obtained by the primary culture of osteoblast-like cells to be endorsed.

Adult↗
PubMed2003

A new method to obtain epithelial and stromal explants from human Corneo-Scleral Discs for the routine culture of corneal epithelial and fibroblast cells.

Acquisition of human corneal cells for culture is hindered not only by the scarcity of donor tissues but also by some of the standard enzymatic and mechanical isolation techniques. Good yields have been reported from full-thickness explant and sclero-limbal pieces. However, due to their greater proliferative capacity, fibroblasts will encroach and subsequently overwhelm epithelial cultures whichever technique is used. The novel approach presented here is to minimise this by removal of the whole stroma from the epithelial layers at the outset. This is achieved by selective sectioning with the Webb mini-microtome developed in the Norwich Eye Research Laboratory. The microtome can be sterilised by alcohol spraying or autoclaving and is small enough to use in the culture hood. A selective cut in the region of the Bowman's membrane results in the isolation of the epithelium from the stroma and thus exposed, the basal epithelial layers are released from contact inhibition to allow growth. The stroma is further cut to produce multiple sections for the culture of fibroblasts. Both pure epithelial and stromal fibroblast cultures have been successfully generated in serum-enriched medium as well as defined serum-free media with growth supplements, from the corneo-scleral discs of donors of all ages.

Cell Adhesion↗
PubMed1981

Lung biopsy with frozen section as a diagnostic aid in patients with congenital heart defects.

In eight patients with congenital heart defects and equivocal preoperative hemodynamic data, lung biopsy with frozen section was performed and quantitative morphometric analysis carried out to help select a palliative or corrective surgical procedure. During catheterization it had been possible in only six of the eight patients to enter the pulmonary artery and obtain pressure measurements; four patients had moderate to severe elevation of pulmonary vascular resistance whereas the other two had only mild elevation of pulmonary arterial pressure, but they were being considered for a Fontan procedure. The lung biopsy tissue was taken inflated and fixed inflated in hot glutaraldehyde. From cryostat sections arterial concentration was assessed relative to alveolar concentration, and the degree of arterial muscularity was assessed by wall thickness and extension of muscle; the more advanced Health-Edwards arterial changes were also evaluated. On the basis of the morphologic assessment, six of the eight patients underwent corrective surgery and two underwent a palliative procedure. Postoperative hemodynamic data available in four of the patients who underwent corrective surgery revealed either a significant reduction in pulmonary vascular resistance or return to a normal level of pulmonary arterial pressure, whereas no change has occurred in the one patient studied who underwent a palliative procedure. Assessment of pulmonary arterial development and structure on lung biopsy with frozen section proved helpful in deciding between a palliative and corrective surgical procedure.

Adolescent↗
PubMed1975

An electron microscopic study of fetal capillary basal laminas of "normal" human term placentas.

Electron microscopic examination of terminal (free-floating) villi of definable normal human term placentas emphasizes the variable fine structural appearance of the fetal capillary basal lamina (FL). The FL assumes both a unilaminar and multilamellar configuration in each placenta examined; the multilamellar portions are usually composed of individual layers which tend to branch and anastomose. The constant indentification of collagen fibrillar profiles between these electron-dense layers argues against the notion that the multilamellar portions of the FL arise via a simple splitting or disaggregation of pre-existing unilaminar FL's.

Adolescent↗
PubMed1975

Synaptic lamellae in retinoblastoma.

During the electron microscopic examination of the retinoblastoma in a 21-month-old girl, we found numerous synaptic lamellae and synaptic vesicles in addition to other known features. These lamellae and vesicles can be regarded as additional proof of the neural origin of retinoblastoma.

Cell Nucleolus↗
PubMed1975

Ocular clinical findings and basement membrane changes in Goodpasture's syndrome.

Goodpasture's syndrome is a rapidly progressive disease characterized by the onset of pulmonary hemorrhage with glomerulonephritis, leading to pulmonary and renal failure. The hallmark of this disease is linear deposition of antibasement membrane IgG in the basement membranes of the kidney and lung. In two cases of nonrhegmatogenous retinal detachment in patients with Goodpasture's syndrome, the first patient demonstrated multiple ischemic areas in the choroid on fluorescein angiography. Histopathologic and immunologic studies of the eyes in the second patient demonstrated macular edema and elevation of the retina in association with choroidal infarction and linear deposition of IgG in Burch's membrane and the basement membranes of the choroidal vessels.

Adult↗