Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Quartz”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1990

[Comparative studies of the effect of quartz glass and quartz DQ-12 in inhalation tests in rats].

Fibrogenic effects of amorphous quartz dusts are discussed more and more during recent years. In order to study alterations due to amorphous silica (quartz glass VP 203-006) in comparison with crystalline quartz (DQ-12), an inhalation experiment in rats was carried out. Male Wistar rats were separated in two dust exposed groups (n = 35) and one control group (n = 30). The experiment was carried out in inhalation chambers with a slowly rotating animal cage for 12 months, 7 h per day, and 5 days per week. The dust concentration was 10 mg/m3. After 4 and after 8 months of inhalation, 5 animals of each group were sacrificed. After 12 months 15 rats of the dust exposed groups and 10 controls were euthanized. The remaining animals were kept for another 12 months post-inhalation period. Regarding the macroscopical appearance of the lungs, the relative organ weights and the histomorphological reaction pattern, marked dust depending differences are obvious. In the lungs of DQ-12-exposed animals diffuse structural changes occur, including fibrosis and severe reaction of macrophages. Histology of lungs from quartz glass exposed animals reveals only a slight and focally arranged cellular reaction with a few collagenous fibers. However, in both dust exposed groups the mediastinal lymph nodes are extremely enlarged with severe fibroses. Additionally, the following blood parameters were determined: lysozyme, ACE, GOT, GPT, and AP. The most pronounced changes are detectable in lysozyme and GOT after DQ-12 exposure. After quartz glass exposure, the levels of these parameters are similar to the controls. These results show that the amorphous quartz tested in this experiment (quartz-glass VP 203-006) has to be considered as a compound with certain biological effects. The establishing of occupational standards seems to be justified. But, assessing the effects, the different physical and/or chemical properties of various amorphous quartz dusts have to be considered.

Alanine Transaminase↗
PubMed1990

Immunomodulation in mineral dust-exposed lungs: stimulatory effect and interleukin-1 release by neutrophils from quartz-elicited alveolitis.

Quartz deposition in the rat lung causes an intense and persistent neutrophil alveolitis leading to parenchymal fibrosis. Bronchoalveolar leucocytes (BAL) from quartz-exposed rat lungs were studied for their effects on splenic lymphocyte proliferation; titanium dioxide (TiO2) was used as a control, non-fibrogenic dust. Seven days after the intratracheal instillation of 1 mg of quartz or TiO2 suspended in phosphate-buffered saline (PBS), BAL were recovered by lavage; the effect of PBS alone was also studied. TiO2-elicited BAL (macrophages greater than 98%) inhibited splenocytes responding to suboptimal phytohaemagglutinin (PHA) more than PBS-elicited BAL (macrophages greater than 98%); the effect was dependent on the BAL:splenic lymphocyte ratio. Quartz-elicited whole BAL (macrophages 49%, neutrophils 51%), and an alveolar macrophage-enriched population with purity of 87% separated from it, were less inhibitory to splenocyte mitogenesis than PBS-elicited BAL. A neutrophil-enriched population, with a purity of 80%, markedly enhanced splenocyte response to PHA. In addition, whole quartz BAL and the macrophage-enriched population obtained from it enhanced the mitogenesis of T cell-enriched lymphocytes at a much lower BAL:lymphocyte ratio. The neutrophil-enriched quartz BAL enhanced mitogenesis substantially more than the whole or macrophage-enriched population from quartz-exposed lung. Supernatants from normal macrophages, PBS BAL, TiO2 BAL, quartz BAL and both alveolar macrophage and neutrophil-enriched quartz populations were assessed for interleukin-1 (IL-1) activity. Quartz-BAL, quartz macrophages and quartz neutrophils all produced significantly higher IL-1 levels than PBS BAL; the supernatants from quartz neutrophils, however, showed the highest IL-1 activity. These findings suggest that quartz-elicited bronchoalveolar leukocytes, especially neutrophils, enhance lymphocyte proliferation and that increased IL-1 secretion by these cells is likely to be the effector molecule involved. These findings have important implications for immune response in mineral dust-stimulated lung and for inflammatory lung disease in general.

Animals↗
PubMed1987

Sustained efficacy of aluminum to reduce quartz toxicity in the lung.

In a recent study of the sheep tracheal lobe model, we have demonstrated that surface chemistry modification of quartz by aluminum lactate significantly alters the biological activity of quartz for at least 2 months after exposure. In the present study, we have extended our observations of the biological reaction of the lung tissue to aluminum treated quartz and to untreated quartz, added lung lavage analyses of surfactant and glycosaminoglycans as additional indicators of activity of the quartz-induced lung injury and analyzed lung lavage and tissue retention of the minerals. The tracheal lobe of 8 sheep was exposed to either 11 mg of aluminum lactate in 100 ml saline (Al group), 100 mg of quartz (Minusil-5) in 100 ml saline (Si group) or 100 mg of quartz treated with 11 mg of Al lactate in 100 ml saline (Si-Al group). The 24 sheep were studied by lung lavage at month 9, 0.13, 1, 2, 3, 5, 7, 9, and 10 and by autopsy at month 10. In the Al group, we found no significant change over time, the pathologic score was 0.38 +/- 0.15 and Si undetectable. In the Si group, we found significant sustained increases in total lavage cells, macrophages, lymphocytes, neutrophils, glycosaminoglycans, lactate dehydrogenase, phosphatidylcholine and phosphatidylglycerol. Histologically we found a macrophagic lymphocytic alveolitis with early nodular silicotic lesions; the pathological score was 3.0 +/- 0.8 at month 10 with an average quartz tissue level of 1.4 +/- 0.4 micrograms/mg. In the Si-Al group, all these changes were significantly reduced early and remained so up to 10 months after exposure; the pathological score was 1.1 +/- 0.4 and lung levels of quartz were undetectable. The data thus demonstrated that Al treatment of quartz significantly reduces the biological activity of quartz and increases its clearance with essentially no detectable particle retention in the lung 10 months after exposure.

Aluminum↗
PubMed1991

Effect of blood leucocyte depletion on the inflammatory response of the lung to quartz.

This study determined the effect of blood leucocyte depletion on the early inflammatory response of the lung to alpha-quartz. F344/N rats were instilled intratracheally with either physiological saline or 2 or 5 mg of alpha-quartz suspended in saline. One day prior to the instillation, half of the rats received an ip injection of rabbit antiserum that had been raised against rat neutrophils. The other half of the rats received an ip injection of normal rabbit serum. One day after the instillation of saline or quartz, the animals were euthanized and observed for changes in blood cell numbers, lung histopathology, and bronchoalveolar lavage fluid (BALF) content of indicators of an inflammatory response and cytotoxicity. The rabbit antiserum depleted the blood of most white blood cells of all types. BALF fluid from saline-instilled animals did not differ between the white blood cell-depleted and the nondepleted animals except for a 20% reduction in numbers of alveolar macrophages in the depleted animals. BALF fluid from the nondepleted, quartz-instilled animals had a dose-dependent increase in content of neutrophils and protein (indicator of an increase in the permeability of the alveolar/capillary barrier) as well as an increase in lactate dehydrogenase and glutathione reductase (cytoplasmic enzymes whose presence extracellularly indicates cytotoxicity), alkaline phosphatase (indicator of type II cell secretory activity), beta-glucuronidase, and acid proteinase (lysosomal enzymes) activities. The higher dose of quartz also elicited an increase in LTB4 and PGE2 content of BALF. GSH content of BALF was decreased by the quartz exposure. The depletion of blood white blood cells prevented the influx of neutrophils into the alveoli of the quartz-exposed rats and decreased the BALF markers of capillary permeability and cytotoxicity (protein content and extracellular cytoplasmic enzymes). The absence of neutrophils in the alveoli had no effect on the lysosomal content of BALF, indicating that the neutrophils were not the source of these enzymes in nondepleted rats exposed to alpha-quartz. The quartz-induced elevation of LTB4 in BALF was not observed in depleted rats, suggesting that neutrophils may be the source of the increase in this leukotriene in the BALF. Both the GSH content and the alkaline phosphatase activity in BALF were enhanced in the absence of alveolar neutrophils. The enhancement of GSH in BALF is consistent with the neutrophils being the source of reactive oxygen species that deplete GSH. The increased alkaline phosphatase activity in the BALF of both the depleted and nondepleted animals is consistent with the type II cell hypertrophy that was induced by quartz instillation and was neutrophil independent.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

The effect of chemical modification of quartz surfaces on particulate-induced pulmonary inflammation and fibrosis in the mouse.

One of the critical steps in the development of crystal-induced lung diseases is thought to be the interaction of crystal surfaces with cell membranes. The effect of chemical modifications of the surface of alpha-quartz on the development of lung disease has been investigated by treating quartz with various organosilanes. The functional groups attached to the quartz surfaces were (-CN), (-CH3), (-NH2), and -(N(CH3)3+). After intratracheal injection of each modified crystal at a constant surface area into mice, pulmonary inflammation and fibrosis were assessed 6 wk postexposure to the crystals by lung wet weight (lung index) and by the level of hydroxyproline in the lung. The crystals showing the highest degree of biologic activity were native quartz, which has a negative charge, -N(CH3)3+ modified quartz, which has a positive charge, and -CN modified quartz, which has no charge. One of the crystals with chemical groups capable of hydrogen bonding, the -NH2 modified quartz, was as unreactive as the crystal preparation modified with a hydrophobic group, -CH3. If the -CH3 and -NH2 modified quartz are compared as a less reactive group with the more reactive native quartz and -N(CH3)3+ modified quartz, these experiments suggest that electrostatic interactions may be more important in determining effective biologic activities than are hydrogen bonding interactions.

Animals↗
PubMed1989

Quartz-dust-induced production of reactive oxygen metabolites by human granulocytes.

We studied the effect of quartz on the production of reactive oxygen species by human polymorphonuclear leukocytes (PMN) in vitro by a chemiluminescence (CL) assay. Quartz caused a rapid dose-dependent CL response in the cells. Diamond dust used as an inert control did not stimulate the production of reactive oxygen metabolite by PMN. The quartz-induced activation of oxygen metabolism was also demonstrated by measuring oxygen consumption, nitroblue tetrazolium reduction, and superoxide and hydrogen peroxide production by PMN. Poly-vinyl-pyridine N-oxide (a quartz surface modifying agent) completely abolished the quartz-induced response, but had no effect on opsonized zymosan-induced CL response of PMN. The effect of N-acetylcysteine (a known antioxidant) was inhibitory to the CL formation induced by both quartz and opsonized zymosan. Our results are in agreement with the hypothesis that quartz-induced production of reactive oxygen metabolites is a possible mechanism by which quartz dust produces chronic inflammation and tissue injury of the lung. Agents interfering with the generation of reactive oxygen metabolites may provide a rationale for treatment of mineral-dust-induced pulmonary disease.

Acetylcysteine↗
PubMed1991

Subchronic inhalation toxicity of amorphous silicas and quartz dust in rats.

The inhalation toxicity of three amorphous silicas (Aerosil 200, Aerosil R 974 and Sipernat 22S) was compared with that of quartz dust. Rats were exposed to 1, 6 or 30 mg Aerosil 200/m3, 30 mg Aerosil R 974/m3, 30 mg Sipernat 22S/m3 or 60 mg quartz/m3 for 6 hr/day, 5 days/wk for 13 wk. Some rats were killed at the end of the exposure period and some were killed 13, 26, 39 or 52 wk after the end of exposure. Clinical signs, body weight, haematology, biochemistry, urinalyses, organ weights, retention of test material in the lungs and regional lymph nodes, collagen content of the lungs, and gross and microscopic pathology were determined in order to disclose possible adverse effects and to study the reversibility, stability or progression of the effects. All test materials induced increases in lung weight, and pulmonary lesions such as accumulation of alveolar macrophages, inflammation, alveolar bronchiolization and fibrosis. In addition, rats exposed to Aerosil 200, Aerosil R 974 or quartz developed granulomatous lesions. Silicosis was observed only in quartz-exposed animals. At the end of the exposure period, Aerosil 200 and quartz had induced the most severe changes. Quartz dust was hardly cleared from the lungs and the changes in the lungs progressed during the post-treatment period, and eventually resulted in lesions resembling silicotic nodules and in one squamous cell carcinoma. Although Aerosil 200 was very quickly cleared from the lungs and regional lymph nodes, the changes in these organs were only partly reversed during the post-exposure period in rats exposed to 30 mg/m3. Aerosil R 974 and the lower levels of Aerosil 200 resulted in less severe, and mostly reversible, changes. The slightest changes were found after exposure to Sipernat 22S, notwithstanding the persistence of this silica in the lungs during the major part of the post-treatment period. The results of this study revealed that only quartz induced progressive lesions in the lungs resembling silicotic nodules. Of the amorphous silicas examined Aerosil 200 induced the most severe changes in the lungs, which only partly recovered, whereas Sipernat 22S induced the least severe, completely reversible lung changes.

Administration, Inhalation↗
PubMed1992

Oxidative stress in vivo and in vitro: modulation by quartz dust and hyperbaric atmosphere.

Changes in the oxidative status in the soluble proteins of bronchoalveolar lavage (BAL) fluid from monkeys were examined during 26 months of individual or combined exposure to quartz dust (5 mg/m3 of DQ12) and a hyperbaric atmosphere (2.5 bar). The oxidation of BAL proteins, assumed to be an indicator for oxidative stress in the lungs, was determined by measuring the amount of carbonyl groups in their amino acid side chains. The carbonyl content of BAL proteins (nmol carbonyl/mg protein) increased steadily to a maximum value of 156% of the control after 6 months exposure to hyperbaric atmosphere, and decreased below 50% of control levels in both the quartz alone exposed group and the group exposed to quartz in combination with a hyperbaric atmosphere. The effect of quartz on the production of reactive oxygen species by BAL cells was investigated in vitro. BAL cells from healthy monkeys preincubated with quartz and stimulated with phorbol-myristate acetate (PMA) produced reduced levels of extracellular superoxide anion and intracellular hydrogen peroxide compared with PMA-only stimulated cells. Thus the lowered carbonyl content of BAL proteins in the quartz exposed groups may have resulted from reduced production of the hydrogen peroxide which is essential for carbonyl formation by phagocytes. Changes in carbonyl content of BAL protein in vivo may be a new indicator for potential subsequent lung damage.

Animals↗
PubMed1990

Comparative clearance of quartz and cristobalite from the lung.

The two silicon dioxide polymorphs, quartz and cristobalite, are known to have different toxicities. The clearance kinetics and biological response of two sources of quartz and one source of pure cristobalite were compared. Models were also developed to show the accumulation of cristobalite in the lungs of Fischer 344 rats as the result of short-term exposures at three different concentrations. The amount of cristobalite cleared from the lung was considerably less than that of the two quartz materials, with little or no clearance after the initial 30 days post exposure. As an indicator of the cellular biological response to the aerosols, total and differential cell counts were measured on bronchoalveolar lavage specimens. Cristobalite showed an early and sustained response with an elevated macrophage, neutrophil, and lymphocyte count through 180 days post exposure. The two quartz materials were not identical in their biological behavior even though they had identical crystal structure and similar trace element analysis. One quartz sample (MIN5) showed an increase in cell response (macrophage, neutrophils, and lymphocytes) approximately 30% that of cristobalite, whereas the other quartz material was not significantly different from control values. In addition, lung hydroxyproline content was greater in the cristobalite-exposed animals.

Animals↗
PubMed1978

Studies on the effect of quartz, bentonite and coal dust mixtures on macrophages in vitro.

The effect of quartz, bentonite and coal dusts as well as the effect of the artificial mixture of these dusts on TTC reduction and extra-and intra-cellular lactate dehydrogenase activity in peritoneal rat macrophages was determined in vitro. The cell-membrane-damaging effect of quartz caused a significant extracellular release of lactate dehydrogenase. Bentonite caused no extracellular enzyme release, which leads us to believe that the biological effect of this dust is shown by decrease in intra-cellular lactate dehydrogenase activity. TTC reduction was inhibited equally by quartz and qentonite. In mixtures of quartz (60%)-bentonite (40%) dust the specific effect of quartz was inhibited by bentonite in vitro and also in vivo. We obtained the same results with coal-quartz-bentonite dust mixtures in vitro. Our experiments show that comparison of the biological effects of artificial dust mixtures and airborne dust samples is justified, and prove that performing various examinations simultaneously give fuller particulars on the probable biological effect of mineral dusts.

Animals↗
PubMed1988

Changes in some histochemically demonstrable enzymes in macrophages exposed to quartz dust in vitro.

Cytochemical studies were carried out on rat alveolar and peritoneal macrophage cultures following exposure to quartz and corundum dusts. Quartz increased the number of ATPase positive cells and brought about an enhancement in the peroxidase and diffusion of the acid phosphatase activity of the exposed cells. In unexposed cell cultures, acid phosphatase activity was higher in alveolar than in peritoneal macrophages and was dependent upon the duration of incubation. Corundum produced no significant effect on the enzyme activity. Quartz treatment did not alter esterase activity whereas corundum exposed cultures showed a decline. A significant increase in mitochondrial succinic dehydrogenase activity was observed in peritoneal macrophages after quartz treatment. The results demonstrate alteration in the marker enzymes of plasma membranes, mitochondria and lysosomes during phagocytosis of quartz dust as the key event of dust cell interaction in vitro.

Acid Phosphatase↗
PubMed1978

Quartz fibers as templates for biopolymers.

The polymerization of silica in water solution to form quartz fibers proceeds by a dehydration process, analogous to condensation polymerization in organic high-polymers, in which monomeric Si(OH)4 groups unite through Si--O--Si bonds with the elimination of H2O. The resulting fibers are structurally polar along the direction of elongation, are enantiomorphous, and generally show stereospecific twisting around the direction of elongation. In these regards the fibers are analogues of biopolymers such as RNA and DNA. Quartz also possesses specific adsorptive relations to a wide range of organic substances including monomer amino acids, short-chain polypeptides, and proteins. These involve hydrogen-bonding between (OH) or silanol groups on the surface of the quartz with active side-groups on the organic molecules, and in part are epitaxial through dimensional coincidences in the interface. Geochemical evidence indicates that quartz was deposited in the early Precambrian ocean either by direct crystallization from seawater or by recrystallization of amorphous silica. What is of interest is the possible role of quartz fibers as a template and co-polymer in the passage of biomonomers in the pre-biotic ocean to the long-chain biopolymers such as nucleic acids and proteins that are involved in life processes.

Adsorption↗
PubMed1992

A quartz crystal biosensor for measurement in liquids.

The detection of anti-human immunodeficiency virus (HIV) antibodies by means of synthetic HIV peptide immobilized on a piezoelectric quartz sensor is demonstrated. The measurement set-up consists of an oscillator circuit, a suitably modified AT-cut thickness-shear-mode quartz crystal with gold electrodes, which is housed in a special reaction vessel, and a computer-controlled frequency counter for the registration of the measured frequency values. The quartz crystal is adapted for a steady operation in liquids at a frequency of 20 MHz. In phosphate-buffered saline solution the oscillator reaches a stability of about 0.5 Hz within a few seconds, of about 2 Hz within 10 min and about 30 Hz within 1 h. The frequency shift due to the adsorption of various proteins to the uncoated sensor surface has been investigated. It can be shown that a stable adsorptive binding of proteins to an oscillating gold surface is feasible and can be used for the immobilization of a receptor layer (e.g. HIV peptide). Specific binding of the anti-HIV monoclonal antibody to the HIV peptide immobilized on the quartz sensor is demonstrated. Control experiments show, however, additional unspecific binding. According to the experiments, the Sauerbrey formula gives a sufficiently accurate value for the decrease of the resonant frequency due to adsorption or binding of macromolecular proteins on the quartz crystal surface.

Biosensing Techniques↗
PubMed1990

Contrasting bronchoalveolar leukocyte responses in rats inhaling coal mine dust, quartz, or titanium dioxide: effects of coal rank, airborne mass concentration, and cessation of exposure.

The aim of this study was to determine the bronchoalveolar leukocyte response to airborne coal mine dust; quartz and titanium dioxide were used as positive and negative controls, respectively. Groups of rats were exposed to airborne mass concentrations of 10 and 50 mg/m3 of the dusts for 7 hr/day, 5 days/week and their bronchoalveolar space was lavaged at time points between 2 and 75 days of exposure, to assess the leukocyte response. This study revealed time-dependent and airborne mass concentration-dependent recruitment of neutrophils and macrophages into the bronchoalveolar region with coal mine dust inhalation but no real difference in the magnitude of the response between coal mine dusts from collieries mining coal of different rank and quartz content although the maximum quartz content in the dusts used was 6%. The inflammatory response was much less than that produced by quartz, at similar airborne mass concentrations, and more than that produced by titanium dioxide which was, in general, a poor inflammogen in the rat lung. Groups of rats were exposed to the airborne dusts for 32 or 75 days, then removed from the exposure chambers, and allowed to recover by breathing room air for a further 64 days. During this recovery period there was marked progression of the leukocyte response with quartz and persistence of the response with coal mine dust. Chronic recruitment of leukocytes to the lungs of individuals inhaling coal mine dust is likely to be an important factor in the development of coal workers' pneumoconiosis.

Administration, Inhalation↗
PubMed1992

The effects of Thorotrast and quartz on the induction of lung tumors in rats.

In a long-term animal study, the combined and separate effects of Thorotrast (colloidal 232ThO2) and silica dust on the induction of lung tumors were investigated. Female Wistar rats were exposed for 29 d to aerosol concentrations of quartz of either 6 mg m-3, 30 mg m-3, or 0 mg m-3 (6 h d-1, 5 d wk-1). After inhalation, one-half of all exposed animals received a single intravenous injection of enriched Thorotrast (600 microL, 2960 Bq 228 Th mL-1). In all quartz-exposed groups the incidence of benign and malignant lung tumors turned out to be more than 40%. The additional Thorotrast treatment (lifelong exhalation of 220Rn) led to a marked shortening of latency times (first lung tumor was found 1 y after treatment) and to a higher total incidence in the animals exposed to 30 mg m-3 quartz (57 of 87 animals with lung tumors = 65.5%). In the group treated only with Thorotrast, three of 87 animals developed lung tumors. Statistical methods that correct for intercurrent mortality showed a significant increase of the lung tumor risk with respect to Thorotrast treatment, even for the low quartz groups with nearly similar incidences of lung tumors (in the group with ThO2, 39 out of 87 = 44.8%; in the group without ThO2, 37 out of 82 = 45.1%). The tumors were found predominantly in the peripheral regions of the lung and were preceded by proliferation and hyperplasia of the alveolar and bronchiolar epithelium. The results demonstrate a pronounced interactive effect of quartz and Thorotrast on carcinogenesis of the lung. The underlying possible mechanisms are discussed.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1988

Kinetics of the bronchoalveolar leucocyte response in rats during exposure to equal airborne mass concentrations of quartz, chrysotile asbestos, or titanium dioxide.

The kinetics of the bronchoalveolar response was assessed in rats exposed, at equal airborne mass concentration (10 mg/m3), to titanium dioxide--a non-pathogenic dust--and the two pathogenic mineral dusts quartz and chrysotile asbestos. Rats were killed at intervals over a 75 day exposure period and groups of rats exposed for 32 and 75 days after recovery for two months. Bronchoalveolar lavage was carried out and the lavage fluid characterised for cellular content, macrophage activation, and concentrations of free total protein, lactate dehydrogenase, and N-acetyl-beta-D-glucosaminidase. Inhalation exposure to the two pathogenic dusts resulted in an increased number of leucocytes, macrophage activation, and increased levels of free enzymes and total protein. The pattern and magnitude of the responses to quartz and chrysotile differed. Chrysotile caused less inflammation than quartz, and the main cellular response peaked around the middle of the period of dust exposure whereas the highest levels of enzymes occurred towards the end. The difference in timing suggests that macrophages were not available for lavage towards the end of the exposure, owing to their playing a part possibly in deposition of granulation tissue. Quartz caused a greater cellular and enzyme response than chrysotile, particularly towards the end of the dust exposure phase. There was a noticeable progression of inflammation in the quartz exposed groups left to recover for two months, but not in the chrysotile recovery groups.

Animals↗
PubMed1992

Influence of surfactant components and exposure geometry on the effects of quartz and asbestos on alveolar macrophages.

Bovine (BAM) and rat (RAM) alveolar macrophages were incubated in vitro with DQ12 quartz or UICC chrysotile asbestos either alone or in the presence of dipalmitoyl lecithin (DPL). The reaction of the cells of both species to the untreated dust particles was similar qualitatively and quantitatively, with a loss of viability and release of lactate dehydrogenase and N-acetyl-beta-glucosaminidase after 20 hr of incubation. In the presence of DPL, the toxicity of quartz to BAM disappeared completely, whereas the protective influence of the phospholipid was distinctly diminished in the case of RAM. The presence of lavage fluid was less effective than that of pure DPL. There was no protective influence of DPL with asbestos either for BAM or for RAM. The effects of phagocytizable, suspended quartz particles were compared with the effects of the same type of particles fixed on a glass surface to exclude the possibility of phagocytosis. The effect of the suspended particles on the viability and release of enzymes was more pronounced than that of the fixed particles. On the other hand, superoxide anion production was stimulated to a much higher degree by the fixed quartz particles. This could be explained by the continuing contact of the outer cell membrane with the silica surfaces, whereas free particles were rapidly phagocytized. The release of lysosomal enzymes induced by fixed quartz particles was a secondary phenomenon following cell death.

1,2-Dipalmitoylphosphatidylcholine↗