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PubMed1997

Aluminum ions in analysis of released fluoride from glass ionomers.

OBJECTIVES: Aluminum ions interfere with fluoride determination when an ion-selective electrode (ISE) method is used. This study examined the effect of the presence of aluminum ions on the determination of fluoride ions released from glass ionomers. METHODS: Disk-shaped specimens of five different commercial glass ionomers were immersed in deionized distilled water at 37 degrees C for one day or up to seven weeks. The amounts of released aluminum were determined by atomic absorption spectrophotometry, whereas the released fluoride was quantitated using a fluoride ISE with TISAB plus two different decomplexing agents for aluminum (CDTA or sodium citrate-potassium nitrate) or TISAB only. RESULTS: Released amounts of aluminum and fluoride ions were found to be significantly different among the five different glass ionomers tested. Based on preliminary examination of the effect of the amount of aluminum ions on the measured value of fluoride, it was found at the end of one day for some of the glass ionomers that the fluoride concentrations measured without decomplexing agents were significantly lower than those measured with decomplexing agents, depending on the amounts of aluminum in the solution. However, since all the glass ionomers tested leached out most the aluminum ions by seven days, the measured fluoride concentrations were not affected by a small amount of released aluminum from the glass ionomers immersed longer than seven days. CONCLUSIONS: When fluoride release from the glass ionomer is determined using ISE, care must be taken with the experimental design and analytical procedures to eliminate the interference by aluminum ions.

Aluminum↗
PubMed1997

Selective hyperexpression of c-jun oncoprotein by glass fiber- and silica-transformed BALB/c-3T3 cells.

Mining and mineral processing are important industries in the United States. A large number of workers are potentially exposed to silica during mining and to glass fibers during manufacturing. There is a concern regarding lung cancer risk among workers exposed to silica and glass fibers. Our previous studies showed that both glass fibers and silica induced transformation of BALB/c-3T3 cells. In order to explore the relationship between silica and glass fiber-induced cell transformation and oncoprotein expression, the protein products of seven proto-oncogenes (c-K-ras, c-H-ras, c-sis, c-myc, c-myb, c-erb B1 and c-jun) and one tumor suppressor gene (p53) were examined in BALB/c-3T3 cells transformed by glass fibers or silica using immunoblotting with specific monoclonal or polyclonal antibodies. The results showed that all transformants, including eight induced by glass fibers and eight by silica (Min-U-Sil 5), were positive for c-jun protein expression; the level of c-jun protein was elevated 8-21-fold in these transformants. Other protooncogene proteins in transformed cells were either not detectable or not different from non-transformed cells. These results suggest that the overexpression of c-jun is common in BALB/c-3T3 transformed cells induced by glass fibers or silica. It seems, therefore, that the expression of c-jun may play an important role in the transformation process.

3T3 Cells↗
PubMed2001

Accidental sharp force fatalities--beware of architectural glass, not knives.

In a retrospective evaluation of 799 consecutive autopsies of victims of sharp force performed between 1967 and 1996 in Münster and Berlin, only 18 cases (2.3%) were classified as accidents. A typical pattern was present in 15 cases: inebriated adults (1.4-3.6g/l BAC) fell into an architectural glass surface in the form of a door or window (12 cases), an aquarium, a mirrored wardrobe or a telephone cell. Another man fell into a large drinking glass. Many victims in this group showed multiple scratches, abrasions and superficial incisions as well as one or more deep tear/cut/puncture injury. The wound margins can be clean-cut or irregular and abraded. Death was mostly caused by exsanguination except for one case of air embolism and one case of cerebral injury. The fatal injuries were produced by large and dagger-like slivers of glass, by sharp-edged fragments of glass remaining inside the frame or by a portion of glass which fell down and acted in a way similar to a guillotine. Ordinary types of flat glass were involved in all cases and it is not until the impact that sharp fragments or cutting edges are produced. So the motion of the person commonly provides the force necessary for a fatal injury. This was also true for the remaining two cases not involving architectural glass. A farmer suffered cerebral injury from a fall into the long prong of a pitch fork, and the wounding agent was a knife in only one case. A man who stated that he had fallen into the knife in his hand died from pneumonia after inadequate therapy following a single stab injury to the periphery of the left lung and liver. Accidents where the victim is killed by his own knife therefore appear to be extremely rare.

Accidental Falls↗
PubMed2000

Adsorption of endotoxin on glass in the presence of rhIL-11.

Poor recovery of spiked endotoxin in the Limulus amebocyte lysate assay (LAL assay) was observed in the presence of recombinant human interleukin-11 (rhIL-11), a cationic, hydrophobic protein. Detection of endotoxin activity remaining in the empty glass tubes in which endotoxin and rhIL-11 mixtures were incubated indicated adsorption of endotoxin on glass. At low concentrations of rhIL-11, a correlation between endotoxin adsorbed on glass and a decrease of endotoxin in solution was observed. Adsorption of rhIL-11 on glass correlated with adsorption of endotoxin, which indicates that rhIL-11 mediates adsorption of endotoxin on glass. Consequently, adsorption of endotoxin on glass may occur in the presence of other substances which bind to both of endotoxin and glass.

Adsorption↗
PubMed2001

Adsorption of endotoxins on glass in the presence of cationic proteins.

Endotoxin activity was detected in empty glass tubes where endotoxins were incubated with lysozyme, histone or RNaseA, indicating adsorption of endotoxins on glass in the presence of cationic proteins. In the case of lysozyme, the recovery of spiked endotoxins (90.0%) using polystyrene tubes for incubation was much greater than the recovery (28.5%) using glass tubes, suggesting that lysozyme-mediated adsorption of endotoxins on glass is a major cause of poor recovery of spiked endotoxins in the LAL assay using glass tubes. In contrast, the recovery of spiked endotoxins (64.7%) using polystyrene tubes in the presence of the non-cationic protein BSA was less than the recovery (103.9%) using glass tubes. The difference in endotoxin recovery using glass or polystyrene tubes in the presence of cationic proteins or BSA can be explained by differences in protein adsorption on the tubes. Consequently, care must be exercised in selecting containers used for the LAL assay of proteins which bind to endotoxins.

Adsorption↗
PubMed2000

Effect of light-cure time on the initial shear bond strength of a glass-ionomer adhesive.

With the introduction of photosensitive (light-cured) restorative materials in dentistry, various methods were suggested to enhance the polymerization of these materials including layering and the use of more powerful light-curing devices. The purpose of this study was to determine the effects of increasing the light-cure time on the initial shear bond strength (in the first half hour) of a resin-modified glass-ionomer adhesive. Eighty-six teeth were divided into 4 groups according to either; (1) the adhesive system used, namely resin, reinforced glass ionomer, or composite, and (2) the light-cure time for the glass ionomer adhesive, namely 40, 45, and 50 seconds. The bonding approach followed the manufacturer's instructions unless otherwise specified. The results of the analysis of variance comparing the 4 experimental groups (F = 19.4) indicated the presence of significant differences between the groups (P =. 0001). In general, the shear bond strength was greater for the composite adhesive system (¿x(-) = 5.2 +/- 2.9 MPa), followed by the 2 groups bonded with the resin-reinforced glass-ionomer adhesive and light cured for 50 seconds (¿x(-) = 3.8 +/- 1.1 MPa) and 45 seconds (¿x(-) = 3.4 +/- 2.7 MPa). On the other hand, the shear bond strength was significantly lower for the group bonded with the glass ionomer adhesive and light cured for 40 seconds only (¿x(-) = 0.4 +/- 1.0 MPa). The present findings indicated the following: (1) the resin-reinforced glass-ionomer adhesive has a significantly lower shear bond strength in the first half hour after bonding when compared to a composite resin adhesive; (2) the initial bond strength of the glass-ionomer adhesive was significantly increased by increasing the light-cure time for an additional 5 to 10 seconds; (3) the mean increase in the shear bond strength between 5 and 10 seconds of additional light curing was not significant but the variability was less with the longer cure time.

Acrylic Resins↗
PubMed1994

Shear bond strengths of a glass ionomer for direct bonding in orthodontics.

This study was undertaken to compare the shear bond strengths of mesh-backed orthodontic buttons bonded to human enamel using a glass ionomer marketed for direct bonding in orthodontics, both in conjunction with, as well as without, enamel etching and to compare the results with a no-mix composite bonding resin. Freshly extracted noncarious human premolar crowns were used, to which mesh-backed metal orthodontic buttons were bonded to the lingual surfaces with one of three methods: group 1, glass ionomer without enamel etching; group 2, glass ionomer with enamel etching; and group 3, with a no-mix orthodontic bonding resin with enamel etching. After being stored in water for 48 hours at 37 degrees C, the samples were tested to failure in an Instron with the Bencor testing system. The data were statistically analyzed with the Mann-Whitney U test. The debonded specimens were visually inspected in respect of failure mode. The no-mix bonding resin had a significantly higher shear bond strength than the glass ionomer cement. Enamel etching with 37% orthophosphoric acid increased the mean shear bond strength of the glass ionomer, however, not significantly. Less cement remained on enamel after debonding when the glass ionomer was used when compared with residual resin when the no-mix bonding resin was used. Clinical research by several investigators is advised to determine the bond failure rate of glass ionomers when used in conjunction with orthodontic bracket bonding.

Acid Etching, Dental↗
PubMed1999

The effect of delayed light exposure on bond strength: light-cured resin-reinforced glass ionomer cement vs light-cured resin.

Under clinical situations, the intervals between material mixing and light exposure during bracket bonding using light-cured resin-reinforced glass ionomer cement may vary for each individual bracket. This study evaluates the bond strength of light-cured resin-reinforced glass ionomer cement subjected to various time intervals between material mixing and subsequent light exposure. This investigation was conducted in two parts. The first part consisted of measuring the enamel surface temperature to define the conditions under which the second part of the study was carried out. One hundred fifteen subjects, 63 males and 52 females, participated in this study. The over-all mean temperature as measured with a noncontact infrared thermometer was 31.9 degrees C. The second part of this study assessed tensile and shear bond strengths of light-cured resin-reinforced glass ionomer cement subjected to immediate light exposure (time interval, 5 minutes) and bond strengths subjected to light exposure at 10, 20, and 40 minutes after material mixing. Light-cured resin-reinforced glass ionomer cement was then compared with light-cured composite resin. Mean tensile and shear bond strengths of light-cured resin-reinforced glass ionomer cement exposed after 40 minutes were 4.5 MPa and 20.5 MPa, respectively. This represented a reduction of approximately 20% when compared with the 5-minute group. Scheffé test showed no statistically significant differences between any two time intervals. Mean bond strengths of the light-cured resin decreased with time. Tensile and shear bond strengths of light-cured resin indicated high statistical significance within groups across time. It could therefore be concluded that the bond strength of light-cured resin-reinforced glass ionomer cement was not affected by the timing of visible light exposure; whereas, the bond strength of light-cured resin decreased as time intervals increased. Light-cured resin-reinforced glass ionomer cement may thus serve as an advantageous alternative to composite resin for bracket bonding.

Adolescent↗
PubMed2003

Influence of the glass packing on the contamination of pharmaceutical products by aluminium. Part III: Interaction container-chemicals during the heating for sterilisation.

The interaction of chemicals with the container materials during heating for sterilisation was investigated, storing the components of parenteral nutrition solutions individually in sealed glass ampoules and in contact with a rubber stopper, and heating the system at 121 degrees C for 30 min. Subsequently, the aluminium content of the solutions was measured by atomic absorption spectrometry (AAS). The assay was also carried out with acids, alkalis and some complexing agents for Al. The containers were decomposed and also assayed for aluminium. 30 different commercial solutions for parenteral nutrition, stored either in glass or in plastic containers, were assayed measuring the aluminium present in the solutions and in the container materials. The results of all investigated container materials revealed an aluminium content of 1.57% Al in glass, 0.05% in plastic and 4.54% in rubber. The sterilisation procedure showed that even pure water was able to extract Al from glass and rubber, 22.5 +/- 13.3 microg/L and 79.4 +/- 22.7 microg/L respectively, while from plastic the aluminium leached was insignificant. The Al released from glass ampoules laid between 20 microg/L for leucine, ornithine and lysine solutions and 1500 microg/L for solutions of basic phosphates and bicarbonate; from rubber stoppers it reached levels over 500 microg/L for cysteine, aspartic acid, glutamic acid and cystine solutions. Ion-exchange properties and influence of pH can explain the interaction of glass with some chemicals (salts, acids and alkalis), but only an affinity for aluminium could explain the action of some amino acids and other chemicals, as albumin and heparin, on glass and rubber, considering the aluminium release. Experiments with complexing agents for Al allowed to conclude that the higher the stability constant of the complex, the higher the Al release from the container material.

Aluminum↗
PubMed1999

Kinetics and thermodynamics of free flavins and the flavin-based redox active site within glucose oxidase dissolved in solution or sequestered within a sol-gel-derived glass.

We report on the steady-state and time-resolved fluorescence from the redox active site flavine adenine dinucleotides (FADs) that are bound to glucose oxidase (GOx) when this enzyme is dissolved in aqueous solution or sequestered within a sol-gel-derived glass. To the best of our knowledge, this represents the first report on the actual dynamics of an enzyme active site when the enzyme is part of a sol-gel-derived glass. The results from these experiments show that the "free" FAD intramolecular folding/unfolding kinetics are slowed 3-10-fold within the glass vs solution. The intramolecular exciplex formation event (i.e., excited-state FAD residue folding/unfolding) is completely arrested for the GOx-bound FAD if the enzyme is sequestered within a glass in the absence of glucose. This is significantly different from the behavior of GOx dissolved in solution. However, despite this difference in behavior, the GOx molecules that are sequestered within the glasses continue to function somewhat like GOx dissolved in aqueous solution if they are challenged with glucose. We also found that the GOx molecules do not leach from the glass and they exhibit rotational mobility that is only 2-fold less than GOx dissolved in aqueous solution at 20 degrees C. In aqueous solution or within these glasses, the enzyme pocket that hosts the FAD redox sites opens up by 25-30% when GOx is challenged with glucose. Finally, we present preliminary analytical results for film-based sol-gel-derived biosensors that contain GOx, L-amino acid oxidase or cholesterol oxidase wherein the intrinsic FAD fluorescence produces the analytical signal.

Binding Sites↗
PubMed2004

In vitro and in vivo assessment of a glass slow fluoride releasing device: a pilot study.

AIMS: The aims were to evaluate a) whether a slow release fluoride-glass pellet (SFG) would be retained in the mouth and release fluoride (F) over a long period of time, b) what concentrations of F in the glass would provide ideal intra-oral saliva F concentrations and c) whether an SFG would affect blood plasma concentrations of F after swallowing compared with ingestion of a commercial NaF tablet. METHODS: a) A prototype SFG was attached to a maxillary molar of a volunteer. Baseline saliva F concentrations were measured prior to glass placement, daily in week one; one day a week for weeks two to three and then one day a month up to 18 months. Four subjects had the SFG for six months with saliva F concentration assessments at periodic intervals. b) SFGs containing F at 13.3%, 18.3% and 21.9%, and an improved solubility, were tested using three volunteers and saliva F concentrations measured. c) Five volunteers each swallowed either a SFG or a NaF tablet. Blood plasma samples were taken at baseline and F measured at time intervals of 2.5, 5, 10, 20, 30, 45, 60, 90 and 120 mins post-ingestion. RESULTS: a) The prototype SFG were successfully retained and released F into saliva; mean concentrations of 0.035 mg L(-1) were achieved lasting for over 18 months. Overall saliva F concentrations were approximately doubled. Analysis of the pellet at the end of use showed it still contained some F possibly indicating a recharging effect. b) The 13.3% F concentration SFG produced significantly higher saliva F levels than the two other concentrations tested. The two higher concentration F glasses contained aluminium as part of the formulation of the glass structure, which is known to bind F whereas the 13.3% glass contained F alone. c) While blood plasma F levels increased after ingestion of the NaF tablet there was no increase in F when the SFG was swallowed. CONCLUSION: A slow release F containing glass device showed promise as a means to enhance intra-oral F saliva concentration.

Adult↗
PubMed1999

Surface roughness evaluation of resin modified glass-ionomers polished utilizing poly(acrylic acid) gel.

The differences in polishability of modified and conventional glass-ionomers were studied following different polishing procedures. Specimens of conventional glass-ionomer (Fuji II(R)), resin modified glass-ionomer (Vitremer(R)) and compomer (Dyract(R)) were prepared and polished using either Soflex(R) or Enhance(R) discs with either aluminum oxide or poly(acrylic acid) gel as polishing agents. Surface roughness of the specimens was evaluated by profilometric measurements and electron microscopic examination. It was shown that Soflex(R) discs manifest superior polishing effect on glass-ionomers and resin modified glass-ionomers compared to the Enhance(R) system, although no significant differences were found for the compomer specimens. Addition of poly(acrylic acid) gel as a polishing agent reduced surface roughness of conventional glass-ionomer and resin modified glass-ionomer specimens and did not significantly affect the compomer specimens.

Acrylic Resins↗
PubMed2002

Use of woven glass fibres to reinforce a composite veneer. A fracture resistance and acoustic emission study.

The aim of this study was to investigate the possibility to reinforce the mechanically interlocked veneer of a porcelain-fused-to-metal (PFM) crown by woven glass fibre. A simulated situation to repair a fractured porcelain veneer was used in the experimental test set-up. A brass jig made into the shape of a framework of PFM maxillary central incisor crown with a retentive area at the palatal side of the incisal edge was used. A veneer were made with a restorative hybrid composite on the brass jig (control group). In the test groups, one or two layers of woven polymer pre-impregnated glass fibres (thickness: 0.06 mm/layer) were used by pressing the fibre weaves to the surface of the brass jig. Restorative hybrid composite was applied on the glass fibre weaves. Five veneers were made for all groups and the veneers were not cemented on the test jig. The veneers were loaded from the incisal edge until fracture occurred. The force was measured simultaneously with an acoustic emission analysis (AE) of the fracture propagation. Fracture force values for control veneers were 121 N and for those reinforced with one layer of glass fibres 399 N and for those reinforced with two layers of glass fibres 744 N ANOVA revealed significant difference between the mean values (P=0.003). The AE analysis showed different fracture propagation for the unreinforced and glass fibre reinforced veneers. The results of this study suggests that by placing two layers of woven glass fibres on the retentively shaped metal framework of the PFM crown before applying the restorative composite, considerably higher fracture resistance for the veneer could be obtained.

Acoustics↗
PubMed2005

Interfacial effects on vitrification of confined glass-forming liquids.

Mesoporous silica phases, with uniform pores of dimensions in the 2-30 nm range, offer a uniquely well-defined environment for the study of the effects of two-dimensional spatial confinement on the properties of glass-forming liquids. We report observations by differential scanning calorimetry of the vitrification of o-terphenyl (OTP), salol, and glycerol in hexagonal mesoporous silica (MCM-41 and SBA-15) in a wide range of pore sizes from 2.6 to 26.4 nm. In agreement with previous studies, where a controlled porous glass is used as a solid matrix, the glass transition temperature for o-terphenyl diminishes with decreasing pore size. In contrast to OTP, glycerol shows a gradual increase in glass transition temperature, while in salol a slight reduction of glass transition temperature is observed, followed by an increase, which results in glass transition temperature indistinguishable from that of the bulk for the smallest pores. These results are discussed in terms of liquid-surface interactions in an interfacial layer, monitored by Fourier-transformed infrared spectroscopy in the study. The hydrogen bonding with silica surface silanols dominates the glass transition trends observed in salol and glycerol.

Calorimetry, Differential Scanning↗
PubMed2000

Effect of altering the type of enamel conditioner on the shear bond strength of a resin-reinforced glass ionomer adhesive.

The purpose of this study was to determine the effects of changing the type of enamel conditioner on the shear bond strength of a resin-reinforced glass ionomer within half an hour after bonding the bracket to the tooth. Freshly extracted human molars were collected and stored in a solution of 0.1% (weight/volume) thymol. The teeth were cleaned and polished. The teeth were randomly separated into 4 groups according to the enamel conditioner/etchant and adhesive used: group I, teeth were conditioned with 10% polyacrylic acid and brackets were bonded with a resin-reinforced glass ionomer adhesive; group II, teeth were conditioned with 20% polyacrylic acid and brackets were bonded with a resin-reinforced glass ionomer adhesive; group III, teeth were etched with 37% phosphoric acid and the brackets were bonded with a resin-reinforced glass ionomer adhesive; group IV, teeth were etched with 37% phosphoric acid and the brackets were bonded with a composite adhesive. The results of the analysis of variance comparing the 4 experimental groups (F = 24.87) indicated the presence of significant differences between the groups (P =.0001). In general, the shear bond strengths were significantly greater in the 2 groups etched with 37% phosphoric acid. This was true for both the resin-reinforced glass ionomer (X = 6.1 +/- 2.7 MPa) and the composite (X = 5.2 +/- 2.9 MPa) adhesives. On the other hand, the shear bond strengths were significantly lower in the two groups conditioned with polyacrylic acid. The bond strength of the resin-reinforced glass ionomer adhesive conditioned with 10% polyacrylic acid (X = 0.4 +/- 1.0 MPa) was significantly lower than the group conditioned with 20% polyacrylic acid (&xmacr; = 3.3 +/- 2.6 MPa). The present findings indicated that the bond strength of the resin-reinforced glass ionomer adhesive can be significantly increased in the initial half hour after bonding if the enamel is etched with 37% phosphoric acid instead of being conditioned with either 10% or 20% polyacrylic acid. The clinician needs to take these properties into consideration when ligating the initial archwires.

Acid Etching, Dental↗
PubMed2001

In vitro fatigue resistance of glass ionomer cements used in post-and-core applications.

STATEMENT OF PROBLEM: New glass ionomer cements exhibit better mechanical properties than their older counterparts. However, there is concern about their use as a core material in post-and-core applications. PURPOSE: This in vitro study evaluated the fatigue resistance of 2 new glass ionomer cements, Shofu Hi-Dense and Fuji IX GP, and compared their mechanical behavior as a core material under masticatory load with a silver-reinforced glass ionomer (ESPE Ketac-Silver) and a silver amalgam (Cavex Avaloy LC). MATERIAL AND METHODS: A total of 100 commercial plastic teeth were divided into 4 groups of 25 specimens each. Titanium posts were placed in the prepared root canals, and cores were built up in amalgam, silver-reinforced glass ionomer cement, and the 2 new glass ionomer cements. The post-and-core specimens were prepared for full cast metal crowns, which were fabricated and cemented with glass ionomer cement. Twenty specimens from each group were placed in a mastication simulator and cyclically loaded with a 400 N force for 1.5 million cycles. The 5 remaining specimens were used as controls. The specimens were sectioned and observed macroscopically and microscopically to determine the number of defects (alterations) in each material. Observed defects were verified with the Kruskal-Wallis test, and the 4 core materials were ranked with the Tukey multiple comparisons test. RESULTS: The mean rank sum values of the defects were as follows: Cavex Avaloy LC Amalgam (16.75), Fuji IX GP (38.50), Shofu Hi-Dense (39.53), and ESPE Ketac-Silver (67.22). The amalgam alloy was significantly different (P< .05) from the others. CONCLUSION: Under the conditions of this study, the 2 new glass ionomer cements used as core materials showed a higher number of defects than amalgam. These results suggest that their fatigue resistance may be inadequate for post-and-core applications.

Cermet Cements↗
PubMedDate not supplied

Enhanced derivation of osteogenic cells from murine embryonic stem cells after treatment with ionic dissolution products of 58S bioactive sol-gel glass.

Embryonic stem (ES) cells represent a potentially useful cell source for tissue regeneration. Previously, using factors known to enhance differentiation and mineralization of primary osteoblasts, we were able to generate cell populations enriched with osteoblasts from a murine ES cell source. Dexamethasone was a potent inducer of osteoblast differentiation and the timing of stimulation markedly increased the proportion of osteoblast lineage cells. This study examined whether inorganic stimuli derived from bioactive glasses could affect the differentiation of osteoblasts in an ES-cell based system. Previous work has demonstrated the ability of soluble ions released from bioactive glasses undergoing dissolution in vitro to stimulate gene expression characteristic of a mature phenotype in primary osteoblasts. We report here on the potential of soluble extracts prepared from 58S sol-gel bioactive glass to further enhance lineage-specific differentiation in murine ES cells. Differentiation of ES cells into osteogenic cells was characterized by the formation of multilayered, mineralized nodules. These nodules contained cells expressing the transcription factor runx2/cbfa-1, and deposition of osteocalcin in the extracellular matrix was detected by immunostaining. When differentiating cells were placed in an osteoblast maintenance medium supplemented with soluble extracts prepared from bioactive glass powders, we observed increased formation of mineralized nodules (98 +/- 6%, mean +/- SEM) and alkaline phosphatase activity (56 +/- 14%, mean +/- SEM) in a pattern characteristic of osteoblast differentiation. This effect of the glass extracts exhibited dose dependency, with alkaline phosphatase activity and nodule formation increasing with extract concentrations. Compared with medium supplemented with dexamethasone, which had previously been used to enhance osteoblast lineage derivation, the glass extracts were as effective at inducing formation of mineralized nodules by murine ES cells. When glass extracts were used in combination with dexamethasone, a further increase in the number of nodules was observed (110 +/- 16%; cf. 83 +/- 7% for dexamethasone alone). This study demonstrates the capacity of an entirely inorganic material to stimulate differentiation of ES cells toward a lineage with therapeutic potential in tissue-engineering applications.

Animals↗
PubMed1977

Use of rabbit antiboty IgG bound onto plain and aminoalkylsilyl glass surface for the enzyme-linked sandwich immunoassay.

Rabbit antibody IgG was bound onto aminoalkylsilyl or plain glass rods by simple adsorption. For comparison, rabbit antibody IgG was also bound onto glutaraldehyde-activated aminoalkylsilyl glass rods. These antibody-glass rods were tested by the sandwich procedure using Fab' fragments of rabbit antibody conjugated with beta-D-galactosidase from Escherichia coli. The glutaraldehyde-activated aminoalkylsilyl glass showed the largest capacity to bind antigen and the plain glass showed the smallest. However, the antibody-glass rods prepared by simple adsorption were as useful for the sandwich immunoassay of macromolecular antigens as those prepared with glutaraldehyde. With all the antibody-glass rods prepared, 0.1 to 10 fmol of ornithine delta-aminotransferase from rat liver and 2,4-dinitrophenyl human IgG were measurable. More than 10 fmol of the antigens may be measurable with larger amounts of the antibody-beta-D-galactosidase complexes, although the non-specific binding of the complexes to the solid phase increases to limit the sensitivity of the immunoassay.

Animals↗