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PubMed1999

[Seasonal levels of respirable quartz measured at a site in the metropolitan area of Rome in 1997-8].

After the International Agency for Research on Cancer (IARC), Lyon classified crystalline silica within Class I, i.e. substances for which there is clear evidence of carcinogenicity to man, the need was felt for further studies to quantify the concentration levels and ensuing risks the general population is exposed to. Crystalline silica is a well-known pollutant which has been largely dealt with in literature as far as occupational exposure is concerned. On the contrary, the data resulting from environmental studies are scarce and usually inadequate, hence the importance of determining the levels of quartz (the most common form of crystalline silica) in the respirable fraction of the airborne particulate in urban areas in a reliable way. This paper is the continuation of a previous study which reported data on quartz concentrations in PM10 collected in an urban site of the metropolitan area of Rome in 1994 (the first year PM10 started to be collected). Measurements had been made with a new procedure that involved the use of X-ray diffractometry and silver filters, permitting the reproducible quantification of small amounts of quartz in the urban atmosphere. In the present work we report the mean daily quartz concentrations in PM10 collected for four weeks representative of the four seasons, from May 1997 to February 1998, in the same sampling site as in 1994. We then compare the two sets of data; in addition, we report preliminary estimates of the potential risk of contracting lung cancer for the general population.

Air Pollutants↗
PubMed2000

A 3-year follow-up study of preformed beta-quartz glass-ceramic insert restorations.

OBJECTIVE: The purpose of this study was to evaluate the clinical performance of preformed beta-quartz glass-ceramic insert restorations. METHODS AND MATERIALS: Nine Class I and 30 Class II beta-quartz glass-ceramic insert restorations were placed in 16 patients who were seen regularly by personnel at Umeå University Dental School. The California Dental Association criteria were used to evaluate the restorations at baseline, 6 months, and 1, 2, and 3 years after luting. The occurrence of postoperative sensitivity, the time taken to manufacture each restoration, and certain periodontal conditions were also evaluated. RESULTS: Sixty-nine percent of the restorations were rated satisfactory at the 3-year examination. During the follow-up period, 4 became loose and 7 were fractured or had flaking surfaces. Caries was registered in connection with 1 restoration. Excellent ratings were obtained for marginal integrity, anatomic form, surface, and color in 62%, 84%, 32%, and 44% of the restorations, respectively. There was no statistically significant difference in the occurrence of plaque and bleeding on probing in comparison with the controls. The mean overall time for placement was 38 minutes. The estimated survival rate (Kaplan-Meier) was 59% after 3.5 years. CONCLUSION: The quality of the beta-quartz glass-ceramic restorations in the present study was inferior to that presented in most earlier studies of ceramic or resin composite posterior restorations placed in patients treated at university clinics. Both the technique and the beta-quartz glass-ceramic inserts have to be evaluated in more long-term studies to assess the possibility of their serving as an alternative restorative technique.

Adult↗
PubMed2001

Reactivity of free radicals on hydroxylated quartz surface and its implications for pathogenicity experimental and quantum mechanical study.

We studied the adsorption of hydroxyl radicals and superoxide anion radicals on a hydroxylated alpha-quartz surface using cluster and periodic slab models by means of density functional calculations. Models of two hydroxylated alpha-quartz surfaces--(0001) and (0111)--have been used in the simulations. The hydroxyl radical adsorbs readily on both surfaces. The subsurface Si-O bonds are weakened during the adsorption resulting in surface layer destabilization. This destabilization leads directly to surface disintegration in the case of *OH/(0111) adsorption. The product of the surface disintegration and reconstruction is a surface terminated by silanol groups (Si-OH) and siloxyl radicals (Si-O*). The model calculations suggest that adsorption of *OH on a hydroxylated quartz surface transforms a chemically inert, aged, silanol terminated surface to a very reactive, silicon-based radical terminated surface. The activated surface may then cause oxidative damage to the adsorbed biomaterial. The superoxide anion radical adsorbs on both surfaces, but the adsorption products are only weakly bonded to the surface. The calculated energy barrier for the O2*- activated subsurface Si-O bond dissociation is 10 kcal/mol, which is higher than for the *OH activated process (4 kcal/mol). The calculated weaker bonding to the surface and higher activation energy barrier suggest that the superoxide anion radical will be less efficient in reactivation of an aged, hydroxylated quartz surface than the hydroxyl radical. The importance of the specific geometry of the surface silicon atoms on the surface reactivity and adsorption properties is also discussed. The theoretical predictions are supported experimentally using chemiluminescence to monitor reactivation of the aged silica surface by superoxide anion radicals.

Adsorption↗
PubMed2002

In vitro and in vivo activation of extracellular signal-regulated kinases by coal dusts and quartz silica.

Alveolar type II epithelial cells are the main precursor cells that develop into carcinomas after inhalation of poorly soluble particles (PSP) at overload concentrations, but the mechanisms leading to initial proliferative events in these cells are unclear. In studies here, cell cycle kinetics, mitogen-activated protein kinase (MAPK) signaling events, and gene expression of activator protein-1 family members were investigated in murine alveolar type II epithelial cells (C10) or rats in vivo after exposure to several coal mine dusts (CMDs) of high or low quartz content. In contrast to results using unexposed C10 cells or cells exposed to the nonpathogenic particle glass beads, flow cytometry showed increased numbers of hypodiploid cells and cells in S phase after addition of DQ12 quartz or CMDs. Using a ribonuclease protection assay, increased mRNA levels of fos and jun family members were seen in response to DQ12 quartz and CMD with high quartz content. Increased phosphorylation of extracellular signal regulated kinases (ERKs)1/2 occurred in DQ12- and CMD-exposed cells by Western blot analysis. The use of the hydroxyl radical scavenger tetramethylthiourea blocked S-phase entry by DQ12 and CMDs as well as the phosphorylation of ERKs. Immunohistochemistry on lung sections of CMD-exposed rats showed chronic activation of phosphorylated ERKs in epithelial cells, supporting the possible role of this signal cascade in proliferation of pulmonary epithelium by PSP in vivo.

Animals↗
PubMed2000

[EPR spectroscopy studies on surface reactivity of quartz].

With the technique of Electron Paramagnetic Resonance Spectroscopy (EPR), we studied the surface reactivity of quartz on adsorbing Cu(II) ions from aqueous solution over the pH range from 2 to 11. The surface sorption mass of Cu(II), gamma Cu, is as a function of pH. The Cu(II) surface coverage for powered quartz samples changes from 0 to 10.23%. The EPR spectra can be demonstrated with the coexistence of several binding forms of Cu(II) ions on the surface, that is, (SO)2Cu at pH = 4.7, SOCu2+ at pH = 6.5, SOCu (OH)(4)3- at pH = 7, and SOH...Cu(OH)2(s) at pH = 10. Therefore, the sorption tendency that the Cu(II) ions are either adsorbed at isolate sites or form multinuclear complexes versus three-dimensional precipitates onto the surface of quartz is strongly dependent on the natures of quartz surface and aqueous solution medium.

Copper↗
PubMed2004

[Expression of Smads in lung tissue of quartz-induced pulmonary fibrosis in mice].

OBJECTIVE: To observe Smads protein expression in lung tissue of quartz exposed mice and to explore its association with pulmonary fibrosis in silicosis. METHODS: The experimental mice were divided into control and quartz groups. 0.2 g/kg weight of quartz was injected intratracheally in quartz group. Samples were collected at the 1st, 3rd, 5th, 7th, 14th and 28th day after injection. Immunohistochemical methods with quantitative image analysis were used to assay the protein expression of transforming growth factor beta(1) (TGF-beta(1)), Smad 2/3, Smad 4, and Smad 7 protein levels. Protein expression level is presented by positive unit (PU). RESULTS: Smad 2/3 protein expression increased from day 3, reaching its peak level in day 14 [(42.2 +/- 2.4) PU], and decreased gradually. The elevation of Smad 4 protein level began from day 5, and the highest degree came into day 14 [(40.0 +/- 1.8) PU], decreased thereafter. The expression of Smad 7 presented a decreasing tendency at the beginning and reaching the lowest level in day 14 [(33.5 +/- 3.3) PU]. It seemed to elevate in day 28, but was still lower than the controls. There were positive correlation between Smad 2/3, Smad 4 and TGF-beta(1) (r = 0.91, r = 0.71, respectively, P < 0.05) and also between Smad 2/3 and hydroxyproline contents of lung tissue (r = 0.85, P < 0.05) except Smad 7. CONCLUSION: Smad protein may have certain association with pulmonary fibrosis in silicosis.

Animals↗
PubMed1990

[Interaction of quartz with human erythrocyte membrane--major protein changes and the effect of aluminium citrate].

The changes of the major proteins of human erythrocyte membrane by quartz were analysed by SDS-polyacrylamide gel electrophoresis. The relative mobility of proteins remained unchanged, whilst the relative abundance of Band 3 and PAS-1 proteins decreased (stained with Coomassie blue and PAS). The adsorption of Band 3 on to quartz were dose- and time-dependent. Aluminium citrate can inhibit the quartz adsorptive activity. The results support that the membrane damage of quartz is related to interacting with Band 3 proteins.

Anion Exchange Protein 1, Erythrocyte↗
PubMed1989

Luminol dependent chemiluminescence of quartz and zymosan stimulated neutrophils.

The effect of the opsonization by zymosan and quartz particles on the chemiluminescence was investigated on human neutrophil granulocytes. Opsonization of zymosan enhanced the chemiluminescence response, while opsonized quartz inhibited the chemiluminescence reaction. Calcium ionophore A 23187 treatment did not influence the chemiluminescence of quartz but the light signal in the presence of quartz decreased rapidly. In parallel experiments the protein pattern of zymosan treated neutrophils was investigated by high resolution two-dimensional polyacrylamide gel electrophoresis.

Blood Proteins↗
PubMed1987

The in vitro cellular immune response to quartz.

It is known that macrophages release into medium in vitro biologically active substances which modulate immune response. In recent years, increase attention has been directed towards the role of prostaglandin in macrophage function. Guinea pig splenic lymphocytes and peritoneal macrophage cultures were incubated with quartz (DQ12), Corundum and aspirin as prostaglandin inhibitor. Lymphocyte proliferation measured by 3H-thymidine incorporation, and lymphokine release by Bendixen-Soborg capillary test (MIF) were applied. EA rosetting and phagocytosis were determined for macrophage function assessment. Quartz suppressed the immune response evidenced by reduced 3H-thymidine incorporation and decreased lymphokine production. Aspirin (as a specific prostaglandin synthesis inhibitor) restored the affected by quartz immunological parameters. This observation gives support to the hypothesis that the immunological response to quartz involves macrophage prostaglandin release, presumably as a first step of lipid peroxidation.

Animals↗
PubMed1982

[Histochemical mechanisms in etiology of pulmonary fibrosis after short-term exposure to a mixture of dust and quartz from copper mine].

The authors induced pulmonary silicosis in albino rats by the intratracheal method with 50 mg mixed middling slime from Panaguiriste and quartz dust, dissolved in I ml physiological solution. The animals received a single treatment and were killed on 90th day of the experiment. Some intime characteristics of collagen-forming mechanisms in lungs were followed up via routine histological, histochemical, enzymohistochemical/ acid phosphatase activity, beta-glucoronidase, AS-esterase and lipase/ and autoradiographic/H3 labelled proline/ methods. It was established, that under the effect of both dusts from Panaguiriste mines studied/ mixed dust and pure quartz dust/ considerable deviations developed in the structure of the lungs of the experimental animals in the enzyme activity of acid phosphatase and carbon esterase, accompanied by various forms of fibrosis in the organ, depending on the dust applied. The difference in the composition of both dusts quartz and mixed dust slime - had an effect on the degree of the deviations, but not on their character, manifested in: I. specific protective reaction of organism, with activation of the ferments from the group of carbon esterase in macrophagic elements of interstitium and around the silicotic alterations in the lungs of the experimental animals; 2. inhibition of the maturation of macrophages in silicotic foci and 3. acceleration of the proliferation of fibroblasts with intensification of collagen-formation, accompanied by an enhanced activity of the ferments from the group of carbon esterase and in the cytoplasm of fibroblasts. The authors draw the conclusion that the complex use of routine histological, histochemical and quantitative isotope methods enables the more significant determination of fibrinogenicity of quartz-containing dust even at the early terms of their exposure under experimental conditions.

Acid Phosphatase↗
PubMed1995

Anti-CENP-B response in sera of uranium miners exposed to quartz dust and patients with possible development of systemic sclerosis (scleroderma).

OBJECTIVE: To look for anti-CENP-B antibodies and their diagnostic relevance in patients negative and positive for anticentromere antibodies (ACA) with different risk for the development of systemic sclerosis (SSc), including uranium miners exposed to quartz dust. METHODS: We studied sera of 107 patients with SSc, 121 patients with possible SSc, 202 uranium miners heavily exposed to quartz dust, 14 patients with vibration induced white fingers, and 240 control patients. Subjects were screened for ACA by indirect immunofluorescence on HEp-2 cells (IIF-ACA) and then for anti-CENP-B autoantibodies by an ELISA using eukaryotically expressed human full length recombinant CENP-B protein. RESULTS: All IIF-ACA positive sera of "idiopathic" SSc (N = 19), "idiopathic possible" SSc (N = 6) and other patients (N = 11), and 17 of 19 IIF-ACA positive sera of miners exposed to silica with (N = 13) and without (N = 6) symptoms of SSc reacted with CENP-B in this assay. Of the 622 IIF-ACA negative sera, 28 were found positive for anti-CENP-B. There was a significant increase of the prevalence of anti-CENP-B antibodies in IIF-ACA negative patients with possible SSc (11 of 109) and in miners exposed to silica (11 of 196) compared to a group of men older than 60 years with diseases or symptoms not related to SSc (1 of 138). CONCLUSION: (1) CENP-B is also the major target of the IIF-ACA response in diseases other than scleroderma and in the risk group of miners exposed to quartz dust. (2) Anti-CENP-B antibodies can be found in IIF-ACA-negative sera, particularly in those at risk for SSc. (3) The detection of anti-CENP-B antibodies in miners exposed to quartz dust may indicate a high risk group for developing SSc and reveals possibilities for the study of early pathogenetic changes as well as exogenic and endogenic factors involved in the development of this disease.

Autoantibodies↗
PubMed1996

Transforming growth factor beta expression and transformation of rat lung epithelial cells by crystalline silica (quartz).

Crystalline silica (quartz) induces silicosis and associated peripheral lung carcinomas in rats. The role and pattern of expression of transforming growth factor (TGF)-beta1/beta2 mRNA transcripts were investigated in the fetal rat lung epithelial cell line FRLE, its neoplastic transformants and derived tumors in athymic nude mice. FRLE cells, treated with 100 microgram/cm2 of quartz in serum-free medium, gave rise to phenotypically altered, tumorigenic cells. Quartz-treated, transformed and tumorigenic cells, subcultured directly (QTT-C1) or after growth in soft agar (QTT-C2), formed tumors in athymic nude mice (QTT-T1). Cells subcultured from the tumors (QTT-T1C) were also tumorigenic in nude mice (QTT-T2). QTT-T1 and QTT-T2 tumors were poorly differentiated carcinomas with variable amounts of extracellular matrix-associated TGF-beta1 and desmoplasia. For comparison, a tumorigenic cell line derived from FRLE cells transformed with a mutated K-ras plasmid (RT-C1) and cells subcultured from a corresponding nude mouse tumor (RT-T1) and designated RT-T1C were used. Whereas TGF-beta1 and TGF-beta2 inhibited the growth of QTT-T1C and FRLE cells in a dose-dependent fashion, RT-T1C cells, containing an activated ras gene, were relatively unaffected. TGF-beta1 and TGF-beta2 mRNAs were expressed at higher levels in QTT-T1C cells than in FRLE and TR-T1C cells, and there was an increase in TGF-beta type II receptor (TGR-betaR) mRNA expression in QTT-T1C and RT-T1C cells compared to FRLE cells. Carcinomas in nude mice derived from QTT and RT cells and silicosis-associated lung carcinomas induced in rats by intra-tracheal quartz did not express either active or latent forms of TGF-beta1 protein on immunohistochemistry. The disparity between TGF-beta1 mRNA and TGF-beta1 protein expression in QTT tumors may be due to post-transcriptional regulation of TGF-beta1.

Animals↗
PubMed1996

Trace metal analysis of coal fly ash collected plain and on a quartz fibre filter.

A simple, uniform procedure has been developed for microwave-based digestion of fly ash samples collected from the hoppers of an electrostatic precipitator (ESP), or collected from flue gases on a heat-resistant quartz fibre filter and for subsequent atomic absorption spectrometric analysis of trace metals (Be, Cd, Co, Cr, Cu, Mn, Ni, Pb, V and Zn). HNO(3), HCl, HF and mixtures have been tested as digestion acids. The combination of HNO(3) and HF has been found to be efficient for the digestion of fly ash samples with and without quartz fibre filter material. In spite of the complicated matrix, results with satisfactory accuracy and precision (relative standard deviation below 10% for most of the elements) have been obtained. In the case of analysis of fly ash together with a quartz fibre filter, the calibration curve has to be determined by standard addition to a blank solution containing a dissolved blank quartz fibre filter.

Journal Article↗
PubMed1991

A quartz crystal viscosity sensor for monitoring coagulation reaction and its application to a multichannel coagulation detector.

A quartz crystal viscosity sensor was applied to a coagulation reaction monitoring system. The system consists of 16 oscillating circuits, a channel selector, a frequency counter, a temperature controller and a microcomputer. The system is named the Quartz Chemical Analyzer (QCA). AT-cut quartz crystals (9 MHz) were used as viscosity detectors and were attached to a cell in order to expose only one side of the quartz plate. The system was applied to the detection of the blood coagulation factors VIII (F VIII) and IX (F IX). The activity of these factors was assayed by a single-stage method. A linear relationship was obtained in a double-logarithmic diagram of concentration versus coagulation time with respect to F VIII and F IX in the range 0.05-0.4 unit cm-3 and 0.025-0.2 unit cm-3, respectively.

Biosensing Techniques↗
PubMed2005

Monitoring cell adhesion processes on bioactive polymers with the quartz crystal resonator technique.

The Thickness Shear Mode (TSM) quartz crystal resonator has been extensively used as sensitive sensor in various electrochemical and biological applications. This technique based on the propagation of an ultrasonic shear wave generated by a sinusoidal electric field through a piezoelectric quartz resonator, provides a non-destructive and powerful means to probe changes at solid-solid or solid-liquid interfaces. In this study, TSM was used to characterize cell-polymer interactions developing during the cell adhesion process. TSM sensing was used to monitor the inhibiting properties of bioactive polymers towards fibroblast McCoy adhesion processes. For this purpose, thin films of various bioactive polymers exhibiting either carboxylate or/and sulfonate functional groups were deposited onto the TSM. Measurements of the time variation of the electrical motional resistance in the vicinity of the mechanical sensor resonant frequency were performed as the quartz crystal resonator was either coated with the continuous polymer phase or polymer plus cell suspensions. Cell adhesion processes on these surfaces was investigated by cell counting and the quartz resonator-based technique. Inhibition of fibroblast McCoy adhesion onto thin polymer films of various chemical compositions was analyzed and discussed in the perspective of a possible application of these bioactive polymers to fabricate intraocular lenses able to prevent secondary cataract phenomena.

Biocompatible Materials↗
PubMed2006

3D Gabor analysis of transient waves propagating along an AT cut quartz disk.

Laser detection methods allow the investigation of ultrasonic transient phenomena in both space and time dimensions. Used for the experimental investigation of surface wave propagation along a 2D surface, laser ultrasonic leads to three dimensional (3D) space-time signal collections. The classical high resolution signal processing methods or 3D Fourier Transforms can be used in order to extract the wave propagation information, however these methods are not adapted for identifying where and when the waves are generated. In order to quantify these transient aspects in the space-time-wave number-frequency domains, the 3D Gabor transform is introduced. The 3D Gabor transform properties are presented. The potential of the 3D Gabor for the identification of the local and transient complex wave numbers is illustrated on the propagation of surface waves on a piezoelectric quartz (AT cut, 6 MHz). In this experimental study, the quartz is excited by a voltage pulse and the quartz surface is scanned by a laser vibrometer. The 3D Gabor analysis shows that the circular electrodes borders generate anti-phase surface waves that propagates outside the electrodes, with a strong energy contribution in the low frequency domain (<1 MHz). The transient analysis also points out, for higher frequencies, where the surface waves are generated and how they propagate with respect of both to the geometry of the electrodes and the crystallographic axis of the quartz. These results confirm the theoretical modal analysis and provide new knowledge about the key role played by the electrodes border. This will allow the optimization of the electrodes shape in order to design low frequency Lamb wave sensors.

Journal Article↗
PubMedDate not supplied

Sediment fingerprints: a forensic technique using quartz sand grains.

The analyses of 738 soil and sediment samples taken during the investigation of 20 forensic cases are combined in a database for retrospective comparisons. Quartz sand grain surface textures are combined into grain types which are analysed at one of five orders of classification. This classification also provides frequency data on the number of grain types found in a sample, the individuality of the quartz grain type assemblages and quartz grain type ratios. The technique, developed primarily as an exclusion mechanism, suggests possibilities, in some circumstances, that significant interpretations can be achieved at different orders of classification. The technique provides excellent exclusionary results and, when combined with other independent lines of analysis, is a powerful tool in forensic interpretation because it uses quartz as its discriminatory mineral. The technique also highlights the potential for computer image recognition analysis.

Dermatoglyphics↗
PubMed1999

Genotoxic effects in bacteria of the light emitted by halogen tungsten lamps having treated quartz bulbs.

Traditional halogen tungsten lamps, which are extensively used worldwide for the illumination of indoor environments, have a quartz bulb which transmits not only visible light but also ultraviolet (UV) light. Due to the output of far-UV wavelengths, halogen lamps were found in previous studies to be potently genotoxic in bacteria, clastogenic in cultured human cells, and carcinogenic in hairless mice. This discovery prompted the launching of new halogen lamps, known as UV-Stop, UV-Block, or similar trade names, which have the quartz glass treated in such a way to reduce its permeability to UV radiation. Surprisingly, these lamps are advertised for attenuating discolouration of UV-sensitive materials, such as fabrics, paintings, works of art and furniture, whereas protection of the human skin from potential carcinogenic risks is overlooked. We tested forty-seven 12 V-powered lamps with treated quartz bulb, which were made available by five producers as blind-coded samples. After exposure to either 1000 lx for 30 min or 2500 lx for 60 min, the 50 W lamps from two producers were borderline mutagenic in strains TA100 and TA104 of S. typhimurium, and induced an evident and dose-related DNA damage in the E. coli strain CM871 (uvrA- recA- lexA-), as compared to its isogenic, DNA repair-proficient counterpart WP2. The 50 W lamps supplied by the other three producers also induced a significant genotoxic damage, but only after exposure for 60 min at illuminance levels of 2500 lx or higher. In calibration experiments, one of these three lamp brands was found to induce in 60 min a genotoxic damage which was equivalent to the one induced in just 55 s by a traditional halogen lamp. Therefore, the new types of lamps with treated quartz bulbs provide an appreciable step forward in the safety of halogen lamps, but some output of genotoxic UV radiations does still occur. Moreover, the lamps manufactured by different producers are not equally effective to this respect. By comparison, the simple application of a glass cover to a traditional halogen lamp completely prevented genotoxic effects, even after 60 min of exposure at an illuminance of 10,000 lx. Suitable regulations are urgently needed for controlling the biological safety or artificial illumination systems.

Animals↗