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PubMed1996

Alpha-fetoprotein binding and uptake by primary cultures of human skeletal muscle.

alpha-Fetoprotein (AFP), a serum alpha-globulin mainly synthesized by the fetal liver and the yolk sac, is the major carrier of polyunsaturated fatty acids during embryo-fetal development. One property characteristic of fetal cells undergoing growth and differentiation is their ability to bind and internalize AFP. In the present work, we have studied the binding and endocytosis of AFP by human muscular cells developing in vitro. Primary cultures of human skeletal muscle, obtained from biopsies and examined at two stages of differentiation (myoblasts and myotubes), were incubated for different times, at 0 and 37 degrees C, with a colloidal-gold-conjugated human AFP probe and studied by light and electron microscopy, as well as by laser scanning confocal microscopy in the reflection mode. The results obtained show that (a) human myoblasts in primary culture bind and internalize the protein, probably through specific AFP receptors, (b) this property is strongly reduced or lost in well-differentiated myotubes, and (c) AFP is also bound, throughout culture development, to the extracellular matrix of fusing myoblasts and differentiated myotubes. The physiological significance of AFP uptake by human myoblasts undergoing growth and differentiation may be based on the ability of AFP to carry and deliver fatty acids to fetal cells.

Binding Sites↗
PubMed2001

Modification of gold surface by grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion.

Gold surfaces were first treated in an alkanethiol solution to form self-assembled monolayers (SAMs). The thiolated Au surface was then subjected to Ar plasma pretreatment, followed by air exposure and UV-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA) macromonomer. In comparison with the 3-mercaptopropionic acid-2-ethylhexyl ester (MPAEE) SAM, the (3-mercaptoproply)trimethoxysilane (MPTMS) SAM on Au exhibited higher stability under the conditions of Ar plasma pretreatment. The graft concentration of the PEGMA polymer on SAM-modified Au surface increased with increasing PEGMA macromonomer concentration and UV-graft polymerization time. The modified-Au surfaces were characterized by X-ray spectroscopy (XPS), atomic force microscopy (AFM), and water contact angle measurement. The Au surface with a high concentration of grafted PEGMA polymer could completely repel protein adsorption and platelet adhesion.

Adsorption↗
PubMed1984

Microprobe and SEM analysis of surface coatings on caries-like lesions in enamel after metal ion mordanting and APF application.

The production of tenacious surface coatings on enamel after metal ion mordanting followed by APF has been reported to prevent caries-like lesion initiation in vitro. In this study, similar surface coatings, which may be responsible for the inhibition of lesion progression, were examined using SEM and microprobe analysis. Relatively thick, even surface coatings which were in intimate contact with the enamel surface of caries-like lesions were seen after zirconium and iron (ferric) pre-treatment, but a thinner and unevenly distributed coating was seen after titanium pre-treatment. This latter coating was similar to that seen after APF treatment alone. Fluoride concentrations on the surface and in the subsurface of caries-like lesions were similar for all treatment groups. The surface coatings after zirconium and iron mordanting may be responsible for the greater inhibition of lesion progression than that seen after both titanium pre-treatment and APF treatment alone.

Acidulated Phosphate Fluoride↗
PubMed1984

The structure of a commercial dental Ag-Pd-Cu-Au casting alloy.

The structure of a commercial dental Ag-Pd-Cu-Au casting alloy has been studied by microprobe and X-ray diffraction analyses after various heat treatments. The composition of phases in equilibrium was established. After being annealed at 400 degrees C, 500 degrees C, and 600 degrees C for seven wk, the alloy consisted of three phases: a Cu- and Pd-rich fee phase (alpha 1) with alpha = 0.372nm, a Ag-rich matrix (alpha 2) with alpha = 0.399nm, and an ordered CsCl-type bcc PdCu phase with alpha = 0.296nm. The PdCu phase was not observed above 600 degrees C, and the proportion of the alpha 1 phase decreased sharply above 700 degrees C. After being annealed at 900 degrees C, the alloy matrix was partly decomposed at the Cu-enriched grain boundaries. The decomposed areas grew into the grain interior during subsequent precipitation hardening. No segregation of Au was detected after casting, and the element was evenly distributed throughout the alloy structure after all heat treatments.

Chemical Phenomena↗
PubMed1992

Dentinogenic activity of allogenic plasma fibronectin on dog dental pulp.

The response of ectomesenchymal cells of dog dental pulp to implantation of Millipore filters supplemented with bovine plasma fibronectin was evaluated after observation periods of one or four weeks. Two concentrations of plasma fibronectin were used (0.2 and 1 mg/mL). Experiments also included implants treated with control solutions (PBS or 1 mg/mL of dog albumin). Formation of a layer of elongated, polarized cells was demonstrated in direct contact with the implants treated with 1 mg/mL of plasma fibronectin solution, after one week post-operatively. Microfilamentous organization and orientation of rough endoplasmic reticulum was observed mainly in the supranuclear zone of the polarized cells. Implants treated with the same solution were consistently surrounded by a thick layer of dentinal matrix after four weeks of their exposure to pulp sites. Implants treated with control solutions or with the low concentration of fibronectin never showed any sign of cell polarization and matrix synthesis. These data provide evidence that the pulp cells can express their odontoblastic phenotype in response to a surface containing concentrated fibronectin (even allogenic), without the need of other molecules as exogenous inductive factors.

Albumins↗
PubMed1994

Fracture surface characterization of dentin-bonded interfacial fracture toughness specimens.

Although the current trend in dentin bonding favors the development of a hybrid layer interdiffusion zone for micromechanical bonding, the exact nature of the dentin-composite bond is still unclear. The objective of this study was to characterize the fracture surfaces of specimens used to measure interfacial fracture toughness. Morphological (SEM) and chemical (EDS and XPS) surface analyses were used for characterization. Fracture toughness specimens generally failed along the dentin-bonded interface in agreement with observed clinical failure modes. Four sites of bond failure were identified within the dentin-composite interfaces when All-Bond 2, Scotchbond Multi-Purpose, and Scotchbond 2 were used as the dentinal adhesives. These were located within (1) the smear layer, (2) a resin-modified layer between the interdiffusion zone and the adhesive resin, (3) a well-infiltrated hybrid interdiffusion zone, and (4) a non-infiltrated unsupported collagen layer. The interfacial region had a complex architecture which varied with the nature of the dentin, the dentin surface treatment, and the dentin bonding system. The sites of bond failure appeared to correlate with the interfacial fracture toughness and the extent to which polymerized resin infiltrated and acted to support the organic dentinal structures.

Animals↗
PubMed1997

Ion transport in cultured pig tracheal submucosal gland acinar cells studied by X-ray microanalysis.

The submucosal glands of the airway may contribute more to the airway fluid than the surface epithelium. The cellular mechanisms underlying the regulation of electrolyte and water transport in airway submucosal glands are, however, still poorly understood. Therefore, we attempted to establish a cell culture system to facilitate study of this regulation. Acinar cells were isolated by enzymatic disaggregation from pig tracheal submucosal tissue and cultured on a plastic substrate coated with human placental collagen. The fine structure of the cells in confluent culture was studied by conventional transmission electron microscopy. The elemental content in resting cells and stimulated cells grown on a permeable substrate was studied by X-ray microanalysis. The cultured cells retained structural characteristics (microvilli, secretory granules and desmosomes) of in situ epithelia. The total intracellular Cl and K concentrations significantly decreased after stimulation with the cholinergic agonist acetylcholine, the predominantly alpha-adrenergic agonist norepinephrine, or the beta-adrenergic agonist isoproterenol. Both ionomycin and 8-bromoadenosine 3':5'-cyclic monophosphate (8-bromo-cAMP) caused a marked decrease of the intracellular Cl, K and Na concentrations. Cl- secretion induced by acetylcholine was inhibited by Cl- channel blockers anthracene-9-carboxylic acid and 5-nitro-2-(3-phenylpropyl-amino)-benzoic acid (NPPB), but Cl- efflux induced by 8-bromo-cAMP was blocked only by NPPB. The intracellular Cl and Na content significantly increased and the cellular K content markedly decreased after treatment with ouabain. These results indicate that the cultured acinar cells maintained the structural and functional characteristics of in situ tissue and that this system is suitable for studying aspects of ion and water transport by the airway submucosal gland cells.

Animals↗
PubMed2005

Formation characterization of hydroxyapatite on titanium by microarc oxidation and hydrothermal treatment.

Microarc oxidation (MAO) was performed on titanium in an electrolyte containing calcium glycerphosphate (Ca-GP) and calcium acetate (CA) using a direct current power supply. It was found that the MAO method is suitable forming a ceramic coating containing Ca and P using titanium, and that films display a porous and rough structure on their surface. Samples with a Ca/P ratio of 1.71 were hydrothermally treated in water solution whose pH was adjusted to 7.0-11.0 by adding NaOH at 190 degrees C for 10 h in an autoclave. Hydroxyapatite crystals were precipitated on the film surface after the hydrothermal treatment, and the amount of hydroxyapatite precipitated increased with increasing pH of water solution. The oxide film composition was semiquantitatively analyzed with an electron probe microanalyzer. The microstructures on the sample surfaces were observed by scanning electron microscopy before and after the hydrothermal treatment. The topography of the oxide film was imaged with an atomic force microscope. Its cross section was observed by scanning electron microscopy after being coated with a thin Au film. The surface structures of the films were analyzed by X-ray diffraction.

Adhesiveness↗
PubMed2004

Neuropeptides, apoptosis and ion changes in prostate cancer. Methods of study and recent developments.

It has been suggested that neuroendocrine (NE) cells provide paracrine stimuli for the propagation of local carcinoma cells and that NE differentiation is associated with the progression of prostate cancer toward an androgen-independent state. Apoptosis comprises a critical intracellular defense mechanism against tumorigenic growth and is associated with a number of changes in the elemental content of the cell. The neuropeptides bombesin and calcitonin, which inhibit etoposide-induced apoptosis, also inhibit the etoposide-induced elemental changes in prostate carcinoma cells. This important fact strengthens the link between apoptosis and changes in the intracellular elemental content. This protective effect on etoposide-induced apoptosis appears to be quite similar in androgen-dependent and androgen-independent cell lines. This confirms that neuropeptides confer antiapoptotic capabilities on non-neuroendocrine cells in close proximity to neuroendocrine cells. It can therefore be speculated that certain neuroendocrine peptides can increase the survival and further growth of neighboring cells and may thereby contribute to the aggressive clinical course of prostate tumors containing neuroendocrine elements. In addition, this correlation provides an objective basis for the study of neuropeptide target points and may be helpful for alternative therapeutic protocols using neuropeptide inhibitors in the treatment of patients with advanced prostatic carcinoma. The culture techniques described were, thus, designed in order to achieve two important goals. First, the development of an in vitro model that allows an approach to neuroendocrine differentiation in prostate cancer and its role in apoptosis blockage. Second, the method has been designed in order to permit rapid cryofixation of intact cell monolayers for subsequent x-ray microanalysis.

Apoptosis↗
PubMed1975

Energy dispersive X-ray microanalysis of zymogen granules of mouse pancreas using fresh air dried tissue spread.

Electron microscopy of fresh air dried pancreas spreads revealed a well preserved ultrastructure of pancreatic exocrine cells. The zymogen granules were identified as homogenously electron dense round bodies of approximately 300 nm in diameter, the same as were seen in fresh frozen dried sections. Energy dispersive X-ray microanalysis of zymogen granules and spots 200 nm distant from the granules used as controls disclosed peaks for chlorine, potassium and sulfur in all of five granules examined and in three of them, phosphorus was found in addition to the above elements. The results seem to suggest that pancreatic juice may be contributed from the electrolyte content of secretory granules in contrast to the general assumption that enzymes and electrolytes are separately excreted in pancreatic juice.

Animals↗
PubMed1979

Distribution of corrosion products in teeth restored with metal crowns retained by stainless steel posts.

The nature and distribution of corrosion products in teeth restored with metal crowns retained by stainless steel posts were examined by means of energy-dispersive X-ray microanalysis, microradiography, and electron microscopy. The corrosion products consisted of calcium, phosphorous, iron, chromium, nickel, zinc, stannum and other elements. A possible root fracturing mechanism is discussed.

Corrosion↗
PubMed1993

In vivo wear pattern of experimental composite resins based on different resin monomers.

This study investigated the effects of various monomer systems on composite resin wear in vivo. Experimental light-cured composite resins were prepared employing four different monomer systems: (1) Bis-GMA type, (2) D-2. 6E type, (3) UDMA type, (4) UTMA type. The resin monomers consisted of 70wt% main monomer and 30wt% TEGDMA. These composites contained 80wt% fine quartz. The resins were placed in 2 mm diameter cylindrical cavities located in the occlusal contact area or the contact free area in cast crowns, temporarily set in a mouth. The crowns were removed at monthly intervals, for longitudinal SEM observation. Two months after setting, wear was analyzed, using an electron probe surface roughness analyzer. Microabrasion of the resin matrix and loss of filler particles were observed for all types of monomer systems. The effect of matrix resin systems on occlusal wear was smaller than that of filler systems.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1999

Distribution of nanofillers from a simplified-step adhesive in acid-conditioned dentin.

PURPOSE: This in vitro study examined the interfacial ultrastructure of a nanofilled, simplified-step adhesive (Prime & Bond NT, Dentsply), to determine the distribution of nanofillers within the collagen network of the hybrid layer. MATERIALS AND METHODS: Twenty-four dentin discs were divided into two groups and bonded using two recommended conditioning techniques: Group I, NRC (Non-Rinse Conditioner), and Group II, Conditioner 36 (colloidal silica thickened 36% phosphoric acid). Following conditioning, a single coat of adhesive was applied and light-cured. Dentin discs were then bonded to form disc-pairs and processed for TEM examination. Demineralized, ultrathin sections were examined stained or unstained. Non-demineralized sections were used for STEM/EDX analysis of elemental distribution across the resin-dentin interface. In addition, four dentin discs were bonded with a generic adhesive (HEMA/TBBO) for TEM examination of stained collagen and proteoglycans. RESULTS: In unstained sections of both groups, nanofillers from the adhesive layer were congested around patent tubular orifices, but were not found within the interfibrillar spaces of the hybrid layer. EDX analysis of silicon (Si) showed predominant distribution within the adhesive layer and tubular orifices. Phosphorus (P) was present within the hybrid layer and adhesive layer in Group II. CONCLUSION: It is hypothesized that a) aggregation of the nanofillers within the adhesive resulted in filler clusters that are too large to infiltrate the interfibrillar spaces of the hybrid layer; and b) retention of ground substance within the demineralized intertubular collagen matrix may also have prevented the infiltration of the nanofillers.

Acid Etching, Dental↗
PubMed2002

Magnesium transport through the basal plasma membrane of larval malpighian tubules of Drosophila hydei studied by electron probe X-ray microanalysis.

Magnesium besides calcium is the most important excretion product. In the anterior Malpighian tubules of Drosophila, excretion of magnesium takes place via the hindgut by proteoglycan containing concretions. This study reports on magnesium transport through the basal plasma membrane of the principal cells of the proximal segment of the anterior Malpighian tubules. Measurements by electron probe X-ray microanalysis indicate the existence of two antiporters which transfer magnesium in still unknown stoichiometry from the hemolymph space into the cell: Mg/H and Mg/Na.

Amiloride↗