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At least 109 records · Page 6Linked to original sources
PubMed1995

Superoxide anions in the pathogenesis of talc-induced cerebral vasocontraction.

We have recently reported that sustained contraction of the canine basilar artery induced by the intrathecal injection of talc (crystallized hydrous magnesium silicate) mimicked delayed vasospasm following subarachnoid haemorrhage. The present study aims to examine the pathomechanism underlying talc-induced vasocontraction, from the viewpoint of free radical theory, which has been established as a cause of delayed vasospasm. We estimated the effects of a prolonged intrathecal infusion of human recombinant Cu/Zn superoxide dismutase (hr SOD) on the contraction of the basilar artery caused by the intrathecal injection of talc in beagle dogs, which were assigned to the three groups: G1, sham operation with saline treatment; G2, talc injection with saline treatment; and G3, talc injection with 2 ml of hr SOD (7 x 10(4) U/ml) treatment. Talc administration resulted in the reduction in the angiographic calibre of the basilar artery by 63 and 61% on days 3 and 7 (G2). The treatment with hr SOD (G3) led to a significant attenuation of talc-induced contraction of the basilar artery on days 3 (P < 0.05 vs. G2) and 7 (P < 0.05 vs. G2). In the basilar artery wall of days 3 and 7 in G2, pathological changes such as myonecrosis, cytoplasmic vacuolation and detached intercellular junctions were observed. However, these pathological changes almost disappeared in G3. The present findings suggest that superoxide anions may initiate and/or mediate talc-induced vasocontraction and subsequent structural damage of the basilar artery.

Animals↗
PubMed2004

Electronic transitions in perovskite: possible nonconvecting layers in the lower mantle.

We measured the spin state of iron in magnesium silicate perovskite (Mg(0.9),Fe(0.1))SiO(3) at high pressure and found two electronic transitions occurring at 70 gigapascals and at 120 gigapascals, corresponding to partial and full electron pairing in iron, respectively. The proportion of iron in the low spin state thus grows with depth, increasing the transparency of the mantle in the infrared region, with a maximum at pressures consistent with the D" layer above the core-mantle boundary. The resulting increase in radiative thermal conductivity suggests the existence of nonconvecting layers in the lowermost mantle.

Journal Article↗
PubMed1989

Bradyrhizobium japonicum Survival in and Soybean Inoculation with Fluid Gels.

The utilization of gels, which are used for fluid drilling of seeds, as carriers of Bradyrhizobium japonicum for soybean (Glycine max (L.) Merr.) inoculation was studied. Gels of various chemical composition (magnesium silicate, potassium acrylate-acrylamide, grafted starch, and hydroxyethyl cellulose) were used, although the hydroxyethyl cellulose gels were more extensively investigated. Gel inocula were prepared by mixing gel powder with liquid cultures of B. japonicum (2% [wt/vol]). The population of B. japonicum USDA 110 did not change in each gel type during 8 days of incubation at 28 degrees C. These fluid gels were prepared with late-exponential-growth-phase cells that were washed and suspended in physiological saline. Mid-exponential-growth-phase B. japonicum USDA 110, 123, and 138 grew in cellulose gels prepared with yeast extract-mannitol broth as well as or better than in yeast extract-mannitol broth alone for the first 10 days at 28 degrees C. Populations in these cellulose gels after 35 days were as large as when the gels had originally been prepared, and survival occurred for at least 70 days. Soybeans grown in sand in the greenhouse had greater nodule numbers, nodule weights, and top weights with gel inoculants compared with a peat inoculant. In soil containing 10 indigenous B. japonicum per g of soil, inoculation resulted in increased soybean nodule numbers, nodule weights, and top weights, but only nodule numbers were greater with gel than with peat inoculation. The gel-treated seeds carried 10 to 10 more bacteria per seed (10 to 10) than did the peat-treated seeds.

Journal Article↗
PubMed1977

Primary pulmonary sporotrichosis.

A 34-year-old alcoholic and drug addict developed cavitary pulmonary sporotrichosis that progressed slowly during 6 years. Pulmonary resection and pre- and postoperative therapy with amphotericin B were associated with prompt clinical improvement with no evidence of relapse during a 2-year follow-up. Histologic examination of lung revealed granulomatous inflammation with organisms consistent with Sporothrix schenckii, and interstitial talc (magnesium silicate) granulomas. The latter finding was consistent with the history of intravenous drug abuse. Although the presence of silicates in lung enhances the pathogenicity of some microorganisms, the relation of these findings to the pathogenesis of sporotrichosis in our patient is unclear.

Adult↗
PubMed2001

Continuous fermentation of sugar cane syrup using immobilized yeast cells.

Several strains of Saccharomyces sp. and commercial Baker's yeast were immobilized by adhesion onto chrysotile, a fibrous magnesium silicate (Mg6Si4O10 (OH)8). The activity of the cells is higher when immobilized, mainly for fermentation of 30 to 50% w/v glucose solutions. In the medium containing 30% w/v glucose, the initial fermentation rate increased 1.2-2.5 times. Yields were in the range of 80.4 to 97.3% for the immobilized cells and 72.7 to 84.5% for the free cells. A packed bed reactor for continuous fermentation was set up using one of the tested strains immobilized onto chrysotile. An average productivity of 20 to 25 g.l(-1).h(-1) was obtained in the first 20 d, and an average of 16 g.l(-1).h(-1) was obtained after 50 d of operation.

Journal Article↗
PubMed1994

Sequential morphological changes of the constrictive basilar artery in a canine model of experimental cerebral vasospasm by talc injection.

To demonstrate the possible role of foreign-body reaction to extravasated blood in provoking chronic cerebral vasospasm, talc (crystallized hydrous magnesium silicate) was injected as a non-biologic foreign material into the canine-cisterna cerebellomedullaris, and pathologic changes were followed. Angiographically, this cisternal talc injection induced delayed and prolonged constriction of the basilar artery, without any evidence of so-called early phase cerebral vasospasm that should occur shortly after an insult. Pathologically, around the spastic artery in the subarachnoid space with talc injection, the appearance of a moderate cellular migration coincided with cerebral vasoconstriction, which took place 2 days after the talc injection. In the spastic basilar arterial wall, marked constrictive and degenerative changes including myonecrosis and subintimal proliferation were induced by cisternal talc injection as early as on day 2, and the changes were progressive with time. These pathologic changes were extremely analogous to those of the human autopsy cases with chronic cerebral vasospasm (chronic VS) but more prominent than those observed in the experimental autologous blood-induced model. The present study demonstrated that a foreign-body reaction to talc alone could induce chronic VS in the absence of extravasated blood. Thus, it is possible to consider that inflammatory reactions to extravasated autologous blood in subarachnoid hemorrhage may give rise to chronic VS.

Animals↗
PubMed2000

Hypercalcemia due to talc granulomatosis.

Pulmonary disease due to talc, a group of hydrous magnesium silicates, is almost exclusively encountered after occupational exposure. One form of this rare disorder is talc granulomatosis. In varying degrees, hypercalcemia is typical of granulomatous disease but has not yet been reported in talcosis. We report the case of a former mold maker who presented with hypercalcemia. Laboratory findings indicated extra-renal 1-alpha-hydroxylation of 25-hydroxyvitamin D. Pulmonary infiltrates prompted a lung biopsy that disclosed talc granulomatosis. We suggest that talc granulomatosis should be added to the list of granulomatous disorders capable of causing hypercalcemia due to increased extra-renal 1-alpha-hydroxylation of 25-hydroxyvitamin D.

Aged↗
PubMed2003

Evaluation of the catalytic activity of lipases immobilized on chrysotile for esterification.

In the present work, the ester synthesis in organic media catalyzed by lipases immobilized on chrysotile was studied. Lipases of different sources (Mucor javanicus, Pseudomonas cepacia, Rhizopus oryzae, Aspergillus niger and Candida rugosa) were immobilized on chrysotile, an inexpensive magnesium silicate, and used for esterification of hexanoic, octanoic and lauric acid with methanol, ethanol, 1-butanol and 1-octanol at 25 C in hexane as solvent. The best results were obtained with Mucor javanicus lipase and lauric acid giving yields of 62-97% of ester.

Asbestos, Serpentine↗
PubMedDate not supplied

Ultrastructural and Energy dispersive analysis of inorganic inclusions in a muscle biopsy.

A muscle biopsy that, by light microscopy, exhibited mild atrophy consistent with chronic denervating disease was submitted for ultrastructural analysis. Inorganic structures within the tissue were defined by energy dispersive analysis as aluminosilicates, magnesium silicates, and iron deposits. These structures were localized in the interstitial (intercollagenous) area and in high concentrations within degenerated muscle bundles. An alteration of the blood/muscle barrier has obviously occurred; however, the extent to which the end result commonly occurs in humans is unknown. Clarification of the question raised by this observation will have to be derived from animal studies, and clinicians must have an awareness of the need for electron microscopy/energy-dispersive x-ray analysis in muscle biopsies from patients with similar therapeutic backgrounds.

Atrophy↗
PubMed1999

Munchausen syndrome presenting as pulmonary talcosis.

We describe a patient with self-induced inhalational pulmonary talcosis originally diagnosed as asthma. A 35-year-old female respiratory technologist developed severe asthma that was refractory to steroids and methotrexate. An open lung biopsy specimen showed scattered aggregates of refractile golden crystals within membranous and respiratory bronchioles. The particles ranged in size from 30 to 100 microm and were birefringent when viewed with polarized light. Following review of the lung biopsy specimen, the patient admitted to regularly inhaling large amounts of hospital baby powder. Analysis of the lung biopsy specimen and a sample of the hospital baby powder by x-ray energy dispersion showed identical spectroscopic peaks, including elemental peaks for magnesium silicate. Many patients with self-induced illness lack the picturesque symptomatology classically attributed to Munchausen syndrome. Awareness of these more subtle and varied patterns of presentation may aid in earlier recognition.

Administration, Inhalation↗
PubMedDate not supplied

[Kaopectate in the combined treatment of patients with intestinal infections].

The paper presents results of multiple-modality treatment of patients with acute intestinal infections with making use of the drug preparation Kaopectate incorporating activated attapulgite which is a natural mixture of hydrates of magnesium silicate and silicate of alumina. The above drug has been shown to be endowed with a antidiarrheal and detoxifying activities.

Adult↗
PubMedDate not supplied

Is thoracoscopic talc pleurodesis really safe?

Talc is a mineral defined as hydrated magnesium silicate in its pure form. It is mined in open pits throughout the world. For induction of chemical pleurodesis, talc has been shown to be superior to all other products. The safety of the use of talc for pleurodesis is subject to discussion in the literature. In early days, there was concern about asbestos contamination of talc, which could cause mesothelioma in patients who had undergone talc pleurodesis. The long-term safety of talc was proven in several studies, and today talc for pharmaceutical use is asbestos-free. Today the discussion is concentrated on the early complications of talc; Acute respiratory failure, sometimes with fatal outcome, has been attributed to the intrapleural use of talc particles. In recent animal studies, a relation was demonstrated between the size of talc particles and pulmonary injury as well as dissemination to other organs. Pulmonary injury and dissemination to other organs are related to a talc particle size of less than 10 micro. With certain precautions, talc can be used safely for pleurodesis; Simultaneous bilateral procedures, concomitant pulmonary biopsies and use of more than 5 grams of talc should be avoided. As long as the hypothesis about the influence of particle size on complications has not been confirmed by studies in humans, the use of talc with a large mean particle diameter is to be preferred.

Cardiovascular Diseases↗
PubMed1990

[Experimental surgical model of hydrocele for the use of sclerotherapy].

Sclerosant therapy for different pathological conditions (testicular hydrocele, pneumothorax) is a little known and scantily used procedure in the clinical setting. We have developed a surgical procedure in the dog that permits reproducing adult hydrocele. This experimental model is useful for morphometric assessment of the sclerosant effects of the commonly used agents (magnesium silicate hydrate, carbolic acid, ethanolamine oleate, hydroxytetracycline chlorhydrate and quinacrine chlorhydrate). Our results show that the degree of sclerosis achieved with quinacrine and hydrotetracycline is significantly superior to that obtained with other agents.

Adult↗
PubMed1990

Microscopic colitis: a new cause of chronic diarrhea in children?

From a retrospective study on children who underwent colonoscopy or rectosigmoidoscopy with multiple level biopsies, we selected five patients whose rectocolonic endoscopic aspect was normal and contrasting with the presence of a microscopic colitis on biopsies. These five children had chronic diarrhea (mean duration of 14 months), associated with vomiting (three cases), abdominal pain (two cases), anorexia (two cases), abdominal distension (two cases), and weight loss (four cases). Symptomatic treatment was used in all children: loperamide (one case), trimebutine (three cases), and aluminium and magnesium silicate (two cases). One child received sulfasalazine for 2 months. After 1 year, all patients had normal stools. Rectosigmoidoscopy was performed in four patients and was normal. Biopsies obtained in three cases were normal in two cases and showed a persistent microscopic colitis in one case. Microscopic colitis may be a distinct cause of chronic diarrhea in children.

Biopsy↗
PubMed1985

Disseminated talc granulomatosis. An unusual finding in a patient with acquired immunodeficiency syndrome and fatal cytomegalovirus infection.

The association of disseminated magnesium silicate talc granulomatosis and acquired immunodeficiency syndrome is reported in a male homosexual who used intravenous drugs and who died of overwhelming cytomegalovirus (CMV) infection. Autopsy findings included widespread deposition of talc crystals in the lungs, liver, lymph nodes, bone marrow, and spleen. Typical CMV inclusions were seen in the lungs, kidneys, adrenal glands, gastrointestinal tract, and right eye. There was no evidence of malignancy. Analysis of peripheral blood neutrophil function revealed impaired chemotaxis and chemokinesis, but opsonophagocytosis had remained normal. The CMV infection in the small bowel was extensive and resulted in severe destruction of the muscularis propria and neural plexi, leading to marked dilatation and persistent diarrhea. The terminal course was marked by intractable hypotension, pneumonitis, and malnutrition, which could be attributed respectively to CMV involvement of the adrenal glands, lungs, and small bowel. The etiology and possible role of systemic talc granulomatosis in the development of immunosuppressive illness is reported herein.

Acquired Immunodeficiency Syndrome↗
PubMed1988

A new suspension form of smectite (Liquid 'Diasorb') for the treatment of acute diarrhoea: a randomized comparative study.

An open, multi-centre, general practice study was carried out in 80 patients with acute diarrhoea to compare the effectiveness and tolerability of treatment with a liquid formulation of smectite, a hydrated aluminium-magnesium silicate (Liquid 'Diasorb'), and loperamide. Patients were allocated at random to receive one or other treatment for a maximum of 48 hours. Thirty-three of the patients on the smectite preparation and 30 of those on loperamide had acute diarrhoea of at least 24 hours but no longer than 48 hours in duration. Patients received a daily dose of 6 to 9 g smectite or 8 to 12 mg loperamide, depending on the symptoms. Details of red and white cell counts, serum electrolyte concentrations and stool culture for pathogens and parasites were recorded on entry and after 1 week. The results, judged in terms of resolution of symptoms after 2 and 7 days, doctor and patient assessment of response to therapy, and incidence of side-effects, showed that both treatments were equally effective and well-tolerated. Two patients were withdrawn, 1 patient (Liquid 'Diasorb') because of lack of response and the other (loperamide) because of dryness of the mouth and nausea. Laboratory parameters remained unchanged apart from a slight decrease in leucocytes in both groups.

Acute Disease↗
PubMed1985

Fibrosing peritonitis in a drug abuser.

We report a case of fatal fibrosing peritonitis in a 28-year-old drug abuser. The extensive fibrosis, which was limited to the abdominal cavity, contained birefringent material. Silica was identified by spectrophotometric analysis. Silica is a component of talc (magnesium silicate) used as a drug filler. Relatively small amounts are known to induce fibrosis. The manner of introduction of this material into the peritoneal cavity is hypothetical and includes accidental direct peritoneal contamination during subcutaneous injections, a method used by drug abusers.

Adult↗