Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D06522 (Silica)
 2,396 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The occurrence of malignant histiocytic lymphomas (MHLT) after an intrapleural inoculation of silica and the presence of a hyperplastic or granulomatous reaction to the silica were confirmed in cesarean-derived barrier-maintained inbred W rats. A specific hyperplastic reaction in the silica granulomas preceded the appearance of MHLT. Hyperplastic changes were observed when the absolute monocyte count at weeks 25-30 was slightly higher than that seen in the controls. Silica injected intrapleurally penetrated the thymus tissue but the carbon and coal dusts and the silica, which was administered by other routes, did not involve the thymus. Also, silica was the sole dust, when introduced into the coelomic cavities that produced MHLT, which grew rapidly on entering the thymus. Rats that died with MHLT had widespread dissemination with malignant foci situated most consistently above the diaphragm.
J Natl Cancer Inst 1976 Sep
PMID:Pathogenesis of malignant histiocytic lymphoma induced by silica in a colony of specificpathogen-free Wistar rats. 18 99

The phospholipid and lipid metabolism of mouse peritoneal macrophages has been studied in the presence of various silicogenic dusts and asbestos particles. These extensive kinetic studies were possible as a reproducible method was developed to determine these major cellular constituents after labelling macrophages with 1-14C-oleic acid. The following results have been obtained so far: 1. Silicogenic dusts activate a phospholipase A in macrophages leading to a concentration and time-dependent degradation of lecithin and cephalin. 2. Using low doses of SiO2 (less than 1 mg/10(7) cells) the split-off free fatty acid can still be transesterified into the triglycerides. 3. High doses of silica (greater than 2 mg/10(7) cells) induce also a lipolysis. 4. Silica specifically inhibits a plasma membrane-bound acyltransferase 5. Asbestos particles induce in long-term cultures a moderate degradation of diacylphospholipids with transesterification of 1-14C-oleic acid into the triglycerides.
Inhaled Part 1975 Sep
PMID:The activation of phospholipase A in macrophages after the phagocytosis of silica and other cytotoxic dusts. 19 65

26,27-Oxido-5 alpha-cholestane-3 alpha,7 alpha,12 alpha-triol can be obtained in a homogeneous state in gram quantities by passing it through one PrepPak-500/Silica cartridge mounted in a Waters Assoc. preparative liquid chromatograph. The elution solvent was methanol-chloroform (1:14). The isolated material was analyzed for purity by several chromatographic means and by elemental analysis, and was finally characterized by the usual spectroscopic means. Gas-liquid chromatography of its trimethylsilyl ether indicated the formation of a tetrakis-trimethylsilyl-26-chloro derivative, in addition to the expected tris-trimethylsilylated substance. The structure of the former compound is deduced from the fragmentation and isotope abundance in its mass spectrum and from chemical principles.
J Chromatogr 1979 Sep 21
PMID:Bile acids. LIX. Purification of 5 alpha-anhydrocyprinol by preparative high-performance liquid chromatography. 57 15

In recent years, with the aging of patients with pneumoconiosis, autoimmune diseases as a complication have been observed. One of the reasons for this may be that autoimmune diseases are prone to develop among the elderly. On the other hand, it has been reported that dust itself, such as silica for example, has adjuvant effect. A review of the recent literature published in Japan and abroad was made to clarify the relationship between pneumoconiosis and autoimmune diseases and the following results were obtained. 1) Disorders which accompany pneumoconiosis: Scleroderma, rheumatoid arthritis, systemic lupus erythematosus (SLE), and disorders of the kidney and liver have been reported. In Japan, about 30 cases of pneumoconiosis accompanied with autoimmune diseases have been reported. In many of the reports, patients with pneumoconiosis and scleroderma have a past history of exposure to silica. In both case studies and case control studies, patients with rheumatoid arthritis and history of silica exposure are prone to develop pneumoconiosis. 2) Immunological studies of patients with pneumoconiosis: As for humoral immunity, elevation of polyclonal gamma-globulin, especially IgG, has been often reported together with high positive rate of autoantibodies such as antinuclear antibodies. In cellular immunity, decreased delayed type skin reaction and decreased CD4/8 ratio have been reported. In human leukocyte antigen (HLA) typing the elevated frequency of DR4 has been reported. In the study of BAL increased production of superoxide anion O2- by alveolar macrophages has been observed. 3) EXPERIMENTAL STUDIES: Silica is well known for its toxicity to cells and also for its adjuvant effect. In the German Democratic Republic, patients with scleroderma and history of long term silica exposure are recognized as patients with occupational disease even though pneumoconiosis is not clearly demonstrated on X-ray film. It is difficult from this review to nrake a definite conclusion regarding the relation between silicosis and autoimmune diseases. There is a need to repeat this review of the literature on autoimmune diseases and pneumoconiosis in the near future.
Sangyo Igaku 1992 Sep
PMID:[Relationship between autoimmune diseases and pneumoconiosis]. 140 2

The relationship between biochemical changes in bronchoalveolar lavage fluid (BALF), serum and the lung of different dustexposed rats was studied. Wistar rats were divided into 5 groups: 1. Xingkong chrysotile asbestos (CH-As); 2. Dust in a sieve selection workshop of Xingkong asbestos mine (Dust-Wo); 3. Silica group (SiO2); 4. Titanium dioxide (TiO2) and 5. Normal control group (Control). All the rats were killed in three months after experiment. The results showed that the level of alveolar macrophages (AM), lactic dehydrogenase (LDH) and acid phosphatase (AcP) in each group was marked by related to collagen, lung fat, ceruloplasmin (Cp) and hydroxyproline (HoP) by r and t-test. Among the LDH from BALF, culture fluid and serum, there was also a marked relationship. So the authors pointed out that the BALF especially AM and LDH test could serve as a good and valuable index for detection the condition of pneumoconiosis.
Hua Xi Yi Ke Da Xue Xue Bao 1991 Sep
PMID:[The relationship of biochemical changes among bronchoalveolar lavage fluid serum and lung on dust-exposed rats]. 166 Aug 48

We measured plasma endothelin (ET) in 11 patients undergoing cardiac valve replacement under high dose fentanyl (116.6 +/- 15.4 micrograms.kg-1, mean +/- SD) anesthesia. Arterial blood samples were obtained: 1) before induction of anesthesia (control), 2) just before the start of cardiopulmonary bypass (CPB), and 3) just before the end of CPB. Endothelin levels were analyzed by radioimmunoassay based on double antibody method using Silica ODS suspension. ET concentrations in period 1, 2, and 3 were 3.0 +/- 1.1, 4.2 +/- 1.7 and 4.5 +/- 1.8 pg.ml-1 (mean +/- SD), respectively. There were no significant differences among these three values (P less than 0.05). The results suggest that under high dose fentanyl anesthesia, surgical stress including that of CPB might not affect ET concentration in plasma.
Masui 1991 Sep
PMID:[Changes in plasma endothelin in patients undergoing cardiac valve replacement under high dose fentanyl anesthesia]. 194 12

Chinese hamster ovary-215 (CHO-215) mutant cells are auxotrophic for cholesterol. Berry and Chang (Berry, D. J., and Chang, T. Y. (1982) Biochemistry 21, 573-580) suggested that the metabolic lesion was at the level of 4-methyl sterol oxidation. However, the observed cellular accumulation of lanosterol was not consistent with a defect at this metabolic site. With the use of a novel Silica Sep Pak sterol separation procedure, we demonstrated that 60-80% of the acetonesoluble lipid radioactivity in [5-3H]mevalonate-labeled CHO-215 cells was incorporated into acidic sterols. 7(8),Cholesten-4 beta-methyl,4 alpha-carboxy,3 beta-ol was the dominant end product. In addition to this acidic sterol, 7(8),24-cholestadien,4 beta-methyl,4 alpha-carboxy,3 beta-ol and 7(8),24-cholestadien,4 alpha-carboxy,3 beta-ol were also isolated. Incubation of cell-free extracts with [3H]7(8)-cholesten-4 beta-methyl, 4 alpha-carboxy,3 beta-ol and pyridine nucleotides confirmed that CHO-215 4-carboxysterol decarboxylase activity was less than 1% of that for wild type cells. Thus, a correspondence between decreased 4-carboxysterol decarboxylase activity and the spectrum of accumulated sterol products by intact CHO-215 cells was demonstrated. No detectable cholesterol was synthesized by CHO-215 cells. 3H-Product accumulation studies demonstrated that 7(8),24-cholestadien, 4 beta-methyl,4 alpha-carboxy,3 beta-ol increased prior to its subsequent saturation at the delta 24 carbon. Furthermore, the steady state ratio for delta 24-saturated acidic sterols/unsaturated acidic sterols was dependent on media cholesterol source and amount. Finally, the accumulated acidic sterol(s) were not regulatory signal molecules for the modulation of 3-hydroxy-3-methyl-glutaryl coenzyme. A reductase activity in response to cholesterol availability.
 ...
PMID:Sterol-mediated regulation of mevalonic acid synthesis. Accumulation of 4-carboxysterols as the predominant sterols synthesized in a Chinese hamster ovary cell cholesterol auxotroph (mutant 215). 221 7

The tricarboxylate carrier of bovine liver mitochondria has been solubilized by Triton X-114 and purified by chromatography on hydroxylapatite and Silica Gel 60. The purified carrier could be visualized as a single band in polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate with Mr 37,000-38,000. The carrier, after reconstitution in phospholipid vesicles, catalyzed the exchange of [14C]citrate against citrate, malate, and threo-D8-isocitrate and was inhibited by the specific tricarboxylate carrier inhibitor 1,2,3-benzenetricarboxylic acid.
J Biol Chem 1989 Sep 05
PMID:Tricarboxylate carrier of bovine liver mitochondria. Purification and reconstitution. 254 27

So that a possible involvement in the mineralization of dental plaque could be investigated, the effects of silicic acid on calcium phosphate precipitation were assessed in vitro. By measuring the decrease in Ca2+ concentration (by means of ion-selective electrodes), we determined both spontaneous precipitation and seeded crystal growth from solutions that contained 1 mmol/L calcium, 7.5 mmol/L phosphate, 50 mmol/L Hepes pH 7.2, and various amounts of silicic acid. Polymerized silicic acid, but not its monomer, was found both to cause a 60% reduction in the lag period that precedes spontaneous precipitation and to enhance the growth rate of seeded hydroxyapatite crystals. Silica suspensions showed effects similar to those of polysilicic acid. In all cases, the precipitated material was found to be hydroxyapatite. Whereas seeded brushite crystals grew slowly without silicic acid, hydroxyapatite was the only mineral detected after crystal growth in the presence of silicic acid. Apparently, polysilicic acid acted as a substrate for hydroxyapatite nucleation, inducing secondary nuclei on both hydroxyapatite and brushite crystals. The finding that polysilicic acid could overcome part of the inhibitory effect of a phosphoprotein on calcium phosphate precipitation gave additional support for the idea that polysilicic acid and silica may promote the formation of dental calculus.
J Dent Res 1989 Sep
PMID:The effect of silicic acid on calcium phosphate precipitation. 255 May 33

The role of mononuclear phagocytes in acquired immunity resulting in the intraerythrocytic destruction and elimination of malarial parasites was investigated in the murine model of infection with Plasmodium chabaudi AS. Mice were treated 1 day before or 6 days after infection with agents which either result in augmentation or activation of the non-specific, microbicidal effector function of mononuclear phagocytes or in depletion of cells of this lineage. To examine the effect of agents which activate mononuclear phagocytes. A/J mice, which are susceptible to P. chabaudi AS and exhibit fulminant parasitaemia and death within 10 days of intraperitoneal infection with 10(6) P-RBC, were treated intravenously with muramyl dipeptide (MDP) or liposome-encapsulated MDP-glycerol dipalmitate (MDP-GDP). Treatment administered 1 day before infection was ineffective. Treatment on day 6 post-infection with liposome-encapsulated MDP-GDP (1 microgram) resulted in a significant decrease in parasitaemia on day 8 and survival, while treatment with free MDP (100 micrograms) resulted only in a significant decrease in parasitaemia. To examine the effect of depletion of mononuclear phagocytes, C57BL/6 mice, which are resistant to P. chabaudi AS infection and eliminate the parasite by 4 weeks, were treated intravenously with 3 mg silica. Silica administered 1 day before or 6 days post-infection abrogated resistance resulting in a delay in elimination of the parasite and host mortality. Treatment on day 6 was more effective, with death by day 13 post-infection of 70% of the normally resistant C57BL/6 mice which exhibited fulminant parasitaemia levels. These results thus provide in-vivo evidence that mononuclear phagocytes play a critical role in the elimination of infection with the murine malaria species P. chabaudi AS. Furthermore, these results suggest that the time of administration of agents which alter mononuclear phagocyte function may be important in determining their effect on host antimalarial defences.
Parasite Immunol 1989 Sep
PMID:Role of mononuclear phagocytes in elimination of Plasmodium chabaudi AS infection. 255 63


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