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At least 1,603 records · Page 89Linked to original sources
PubMed1990

Induction of hypoxia in glass versus Permanox petri dishes.

The survival of Chinese hamster ovary cells in culture following graded doses of X rays delivered under aerobic and hypoxic conditions, or treatment with the bioreductive drug SR 4233 under hypoxic conditions, was evaluated as a function of whether cells were plated onto glass or Permanox plastic petri dishes. In the case of treatment with SR 4233, the influence of varying the total volume of medium in the dishes was also studied. While the Permanox petri dishes were sufficient to yield "radiobiological" hypoxia, that is, oxygen enhancement ratios of approximately 3.0 were obtained for X irradiation, they were inferior to glass petri dishes with respect to the hypoxia-selective cytotoxicity of SR 4233. For a 90-min hypoxic exposure to 40 microM SR 4233, the surviving fraction of cells plated on plastic dishes averaged about 50-fold higher than that of cells plated on glass dishes. Although varying the total medium volume did affect the extent of SR 4233-induced cytotoxicity for glass dishes--drug toxicity decreased slightly with increasing medium volume--this was not the case for the plastic dishes, in which the cell survival following a fixed SR 4233 exposure was essentially constant as a function of medium volume. These results suggest, at least for SR 4233, and under these experimental conditions, that Permanox petri dishes are not satisfactory for such studies.

Animals↗
PubMed1990

Stability of fentanyl citrate in glass and plastic containers and in a patient-controlled delivery system.

This study determined the stability of fentanyl citrate stored in glass or polyvinyl chloride containers and the concentrations of fentanyl citrate delivered by the Janssen on-demand analgesic computer (ODAC) system. Solutions containing 500 micrograms of fentanyl citrate (10 mL) were added to 100-mL three glass containers each of 5% dextrose injection or 0.9% sodium chloride injection and to three 100-mL polyvinyl chloride containers of 5% dextrose injection or 0.9% sodium chloride injection. All containers were stored under usual light conditions and at room temperature. Samples were taken immediately and at 0.25, 0.5, 1, 6, 12, 24, 36, and 48 hours. To determine the concentration of fentanyl delivered via the ODAC system, fentanyl citrate injection 2500 micrograms (50 mL) was added to a 500-mL polyvinyl chloride bag containing 5% dextrose injection. The solution was connected to the ODAC system, and samples of bolus demand doses were collected at various times during a 30-hour period. All the samples were assayed by a stability-indicating gas-liquid chromatographic method. For both glass and plastic containers, the mean +/- S.D. recovery of fentanyl after 48 hours was 98.6 +/- 2.3% when the drug was diluted in 5% dextrose injection and 97 +/- 1.5% when the drug was diluted in 0.9% sodium chloride injection. There was no significant difference between the amount of fentanyl recovered from glass containers and the amount recovered from polyvinyl chloride containers. Nor was there any significant difference between the amount of fentanyl recovered from solutions containing 5% dextrose injection and the amount recovered from solutions containing 0.9% sodium chloride injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Gas↗
PubMed1989

Glass-ionomer cements in dental practice: a national survey.

Certain characteristics of glass-ionomer cements would appear to make them desirable dental materials; however, many practitioners are reluctant to use them because of reports of postoperative sensitivity. The members of the Academy of Operative Dentistry were surveyed in order to assess quantitatively and qualitatively the use of glass-ionomer cements in their practices, as well as the incidence and nature of postoperative sensitivity. The following data were collected: 1) the past and present use of glass-ionomer cements, 2) reasons for disuse of glass-ionomer cements, 3) products which are or have been used, and 4) the incidence of and resolution of postoperative sensitivity. The results are presented and discussed. An interesting secondary finding identified that zinc phosphate when used as a luting agent may contribute to postoperative sensitivity more often than is appreciated.

Dental Cements↗
PubMedDate not supplied

The glass ionomer rest-a-seal.

The "glass ionomer rest-a-seal" described is a restorative technique that minimizes removal of tooth structure and protects the glass ionomer from inherent property weaknesses. This technique would seem to have added benefits over the preventive resin restoration where pit-and-fissure decay involves dentin. Glass ionomer cements have become popular as materials with many desirable properties, including an adhesive nature and an ability to release fluoride to adjacent tooth structure. These materials are, however, technique-sensitive and proper application is critical for long-term success. Conservative treatment of pit- and fissure decay is often indicated. By utilization of the preventive resin restoration and now the glass ionomer rest-a-seal, practitioners can improve the long-term dental health of their patients.

Acid Etching, Dental↗
PubMedDate not supplied

[Risk of abnormal absorption of lead in glass decoration workers].

Following the observation of an abnormal lead absorption (PbB 72 micrograms/100 ml) in a young female glass decorator on a routine laboratory test, blood lead levels were measured in glass decorators of the entire area of the Local Health Unit of Treviso (Northern Italy). Abnormal lead absorption was found in a large number of glass workers, the source of exposure being the high content of inorganic lead in the "low-melting" paints that were used (brush and spray painting). Most of the exposed workers were females of fertile age, for whom even a moderate exposure to inorganic lead may constitute a risk during pregnancy. Attempts to reduce lead exposure levels by means of a health education programme and environmental improvements at the workplace were unsuccessful. In conclusion, a reduction in lead absorption in female glass decoration workers can only be achieved by using "low-melting" paints with a lower lead content.

Adult↗
PubMedDate not supplied

[Generation of active forms of oxygen by human peripheral blood neutrophils and lymphocytes during adhesion to glass].

Oxygen activation by neutrophils and human blood lymphocytes at adhesion to glass have been studied by luminol--dependent chemiluminescence. It has been established that the cell interaction with glass leads to the formation of O2-., O2', .OH and H2O2. Chemiluminescence kinetics and the excited--oxygen forms ratio at adhesion were different for neutrophils and lymphocytes. The desorption of cells resulted in a decrease of the chemiluminescent response to neutrophils and lymphocytes when they again adhered to glass and in practically complete inhibition of chemiluminescence induced by adding concanavalin A. It has been determined that at adhesion of neutrophils and lymphocytes to glass different mechanisms of oxygen activation take place.

Cell Adhesion↗
PubMedDate not supplied

Comparison of platelet glass bead retention techniques in patients with clinical bleeding disorders.

Platelet glass bead retention by the Salzman and infusion pump techniques were compared in 36 control individuals, 10 patients with von Willebrand's syndrome and four patients with thrombocytopathies. No significant differences between the results of the two assays were observed. Eleven percent or less of the control individuals had diminished platelet glass bead retention. The mean percentage platelet retention of the von Willebrand's group and the thrombocytopathy group was less than the mean platelet retention of the control group. However, at least 50 percent of the patients with von Willebrand's syndrome had normal platelet retention by both methods. In the thrombocytopathy group, glass bead retention was more consistently diminished. Although an inverse correlation existed between the duration of bleeding time and the platelet retention assays, consistently diminished platelet retention results were observed only when the bleeding time was 18 minutes or longer. It has been concluded by us that while the glass bead retention assays may be helpful in characterizing certain types of platelet disorders, they are not useful screening assays in the diagnosis of von Willebrand's syndrome.

Blood Coagulation Disorders↗
PubMed1988

Lectin-induced adhesion of human platelets to glass. Comparison with the lectin-induced aggregation.

Effects of Phytohaemagglutinin (PHA), Concanavalin A (Con A) and Lens culinaris (Lens) lectins on the adhesion of human platelets to glass surface were studied. All the three lectins tested enhanced platelet adhesion to glass. Concentration-effect curves showed that maximum effect was reached at about 25-30 micrograms/ml. In the presence of autologous plasma both spontaneous and lectin-induced adhesion to glass were diminished. The inhibitory effect of KCN, NaN3, cytochalasin B and partly of colchicin suggests that lectin-induced platelet adhesion to glass is a process depending on cell metabolism and the state of the cytoskeleton. Only PHA was observed to be a potent inducer of platelet aggregation similar to physiological aggregants. Con A had no effect on platelet aggregation but caused shape change which was blocked by metabolic inhibitors. Neither shape change nor aggregation were induced by Lens up to a concentration of 400 micrograms/ml. A comparison between the mechanisms of lectin-induced substrate adhesion and lectin-induced aggregation of platelets is described.

Concanavalin A↗
PubMed1987

[Tissue reaction of the bone marrow to glass ceramic powder in the femurs of rats fed on a low-calcium diet].

Glass ceramic powder was injected into the bone marrow of 36 rats which were fed a low calcium (21 rats) or normal (15 rats) diet. They were sacrificed 7 or 8, 32 and 60 days after treatment. Histomorphometrical measurement revealed that the ratio of length of bone tissue which was in contact with glass ceramic mass to the circumference of each mass was larger in 32-day and 60-day groups than in the 7 or 8-day groups. Osteocyte-like cells were observed in the narrow space between ceramics and bone tissue in all specimens. Giant cells were seen in 1-2% of the glass ceramic surfaces in low calcium diet group and in 0.3% in normal diet group. No inflammatory reaction such as aggregation of lymphocytes nor leukocyte infiltration was observed in any specimens. Eighty-two percent of the surface of glass ceramic mass was covered with bone tissue 60 days after treatment in normal diet group.

Animals↗
PubMed1978

[Coating of metal implants with the bioactive glass ceramics Ceravital].

The bioactive glass ceramic Ceravital forms a physicochemical bonding with bone which is capable of withstanding stress caused by tension. This glass ceramic may already be put to clinical use as replacement for minor osseous parts. However, physical data are limited for maximum stress withstanding or gracile whole ceramic implants. In this study, metal cylinders from an alloy of CoCrMo are initially coated with a bio-compatible adhesive layer of enamel, approximately 0,2 to 0,3 mm thick. The adhesive strength of this kind of enamel amounts to about 120 to 140 kp/cm2. After the enamelling process, the glass ceramic is pressed into the enamel in granules at a particle size of 100 to 200 micrometer. As the first results show, this new process is suitable for the combination of metal implant stability and tissue compatibility of glass ceramic.

Animals↗
PubMed1986

Cancer mortality of an Italian cohort of workers in man-made glass-fiber production.

This study was undertaken in order to examine possible long-term effects, particularly cancer, associated with working in the man-made glass-fiber production industry in Italy (glass wool and continuous filament). All male production workers employed for a minimum of one year between 1944 and 1974 were admitted to the study (1,098 subjects), and their mortality was examined in the period 1944-1983 (21,325 person-years). The vital status ascertainment was successful for 98.9%, of the cohort members. An increased risk of cancer of the larynx was noted based, however, on only four deaths. When contrasted with the values of the local population, the increase proved to be statistically significant after 25 years since first exposure. The higher than expected larynx cancer mortality was confined to workers hired before the age of 25 years, exposed for at least 15 years, who started exposure before 1960 (main production: glass wool), and who belonged to the highest cumulative exposure categories. Known confounding factors could not completely account for the excess observed. Among the numerous studies carried out on man-made glass-fiber workers, only one incidence study in France support our findings. No other increased cancer risks have been suggested by the present study.

Adult↗
PubMed1985

Stability of an analgesic-sedative combination in glass and plastic single-dose syringes.

The stability of a combination of chlorpromazine hydrochloride (6.25 mg/mL), hydroxyzine hydrochloride (12.5 mg/mL), and meperidine hydrochloride (25 mg/mL) in glass and plastic syringes was studied. Syringes (glass 1.5 mL, plastic 3.0 mL) containing the combination drug solution were stored at 4, 25, and 44 degrees C. At 0,7,30,60,90,180, and 366 days after preparation, samples were visually inspected and tested for pH. Drug concentrations were determined by gas chromatography. No significant changes in drug concentration were apparent in any of the samples stored at 4 degrees C or 25 degrees C. Samples in both glass and plastic syringes stored at 44 degrees C turned yellow by day 30 and continued to darken throughout the study period. At the concentrations tested, chlorpromazine hydrochloride, hydroxyzine hydrochloride, and meperidine hydrochloride combined in glass or plastic syringes are stable for 366 days when stored at 4 degrees C and 25 degrees C. Degradation occurs at higher temperatures.

Chlorpromazine↗
PubMed1977

Sorption of Streptococci to glass: Effects of macromolecular solutes.

Macromolecular solutes (albumin, concanavalin A, whole saliva, serum) caused impaired sorption of Streptococcus faecium and Streptococcus sanguis to glass. The inhibitory effect resided chiefly with interactions of the solutes with the glass surface. In the case of sorption of S. sanguis to glass in the presence of parotid fluid, the inhibitory effect was counteracted by a specific attachment of S. sanguis cells mediated by some component(s) of the parotid fluid. Agglutination of the test organisms was in general accompanied by inhibition of sorption. However, when small or unstable aggregates were formed, the number of cells adhering on the glass surface was increased. The findings are discussed with reference to the colonization of teeth by oral bacteria.

Agglutination Tests↗
PubMed1970

Evaluation of various substances to prevent adsorption of tuberculin purified protein derivative (PPD) to glass surfaces.

It is well known that a dilute tuberculin PPD solution (1 IU or 5 IU per dose) very rapidly loses its potency owing to adsorption of tuberculoprotein to the wall of the container into which it is dispensed. The amount of tuberculoprotein adsorbed per cm(2) of glass surface has been measured for phosphate-buffered saline over a wide pH range (pH 1 to pH 10). The maximum adsorption was found at pH 4 (0.31 mug/cm(2)) and the least at between pH 6 and pH 10 (0.15 mug/cm(2)). The rate of adsorption of tuberculoprotein to glass was not changed when the phosphate-buffered saline was replaced by borate-buffered saline. Tuberculin PPD prepared by the ammonium sulfate precipitation method, by the trichloroacetic acid precipitation method and by a combination of both methods adsorbed equally well to glass and no difference in the rate of adsorption for these tuberculoproteins was found.Forty-two substances in addition to Tween 80 were tested for their property to prevent adsorption of tuberculoprotein to glass in dilute tuberculin PPD solutions (50 IU/ml of (14)C-labelled PPD). The most efficient anti-adsorption agents were found to be nonionic surfactants, some ionic surfactants and some colloidal substances; polypeptides and non-surface-active substances of low molecular weight showed little or no anti-adsorption property.The labelling of PPD with (14)C has proved to be a valuable tool, particularly for long-term adsorption studies and for screening substances to be used as efficient anti-adsorption agents. These studies have permitted the selection of agents which could be added to dilute solutions of tuberculin PPD (10 IU/ml to 500 IU/ml or 0.2 mug/ml to 10 mug/ml respectively) in order to avoid loss of potency due to adsorption.

Adsorption↗
PubMed1983

Cellular membranes on glass lens implants--formed in tissue culture by mouse macrophages.

Intraocular lens implants made of glass were exposed to a suspension of mouse macrophages in tissue culture for 48 and 96 hours. After 48 hours the macrophages had formed a dense cellular membrane on the glass surface and some of them had changed into fibroblast-like cells, epithelioid cells, and early stages of giant cells. After 96 hours a firm and continuous proteinaceous capsule had formed on the glass in the interspaces between the cells. The membranes on glass implants were more cellular and more firmly adherent than those seen on plastic implants under the same conditions.

Cell Membrane↗
PubMed1981

[Surface dose reduction achieved by means of a lead glass filter in case of teletherapy with Co 60 radiation (author's transl)].

The surface dose of irradiated patients can be reduced by the insertion of a lead glass filter with a thickness of 4 mm at the ray emergence point of a Co 60 gammatron. The lead glass which is made stable against color alterations by radiation, will absorb the secondary electrons produced by the gamma radiation at the collimator and shutter system of the gammatron. The filter allows to reduce the surface dose in a tissue depth of 0,05 to 0,1 mm by a maximum rate of 16% according to the size of the irradiation field. Measurements were taken with a soft radiation chamber in several tissue depths within and outside the field using three different filtering methods (without any filter, 1 mm plexiglas, 4 mm lead glass). There are essential advantages for teletherapy of deep tumors by the use of a lead glass filter, so that the insertion of such a filter is recommended for all Co 60 units.

Cobalt Radioisotopes↗
PubMed1980

Elevation of the metastable limits and absence of container surface nucleation for calcium oxalate crystallization in a urothelial-lined system as compared to glass containers.

We studied the metastable limits of calcium oxalate supersaturation in glass tubes and in urothelial-lined rat bladders from a solvent system consisting of 0.9 per cent saline. The metastable limit was significantly elevated at 30 min in the urothelial-lined system as compared to the glass-surfaced containers. Heterogeneous nucleation on the container surfaces consistently occurred with the saline solvent in glass tubes as the metastable limit was exceeded. Intraluminal or free-floating crystals (? homogenous nucleation) without container-adherent crystals occurred with the saline solvent in urothelial-lined containers. This study reveals important properties of crystallization in urothelium and emphasizes the potential errors in extrapolating from crystallization studies in vitro in glass containers to crystallization phenomena in biological systems.

Animals↗
PubMed1995

Resin-modified glass ionomer materials. A status report for the American Journal of Dentistry.

The resin-modified glass ionomer materials are hybrid materials of traditional glass ionomer cement with a small addition of light-curing resin, and hence exhibit properties intermediate to the two, with some characteristics superior to conventional glass ionomer materials. Generally, they have the advantages of both such as adhesion to tooth structure, esthetics, fluoride release and rapid hardening by visible light. Issues surrounding other physical properties, such as the mechanism of adhesion, sensitivity to water, long-term wear and strength, need to be addressed and substantiated. There are other considerations, which are not features of the conventional materials, but are of importance with the resin-modified glass ionomer cements i.e. light-curing, which require further research to provide evidence of their behavior. The future for this group of materials is unknown, but the currently available materials appear to be promising.

Bisphenol A-Glycidyl Methacrylate↗