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PubMed2004

Bone formation within alumina tubes: effect of calcium, manganese, and chromium dopants.

Alumina tubes (1.3mm outer diameter, 0.6mm inner diameter, 15 mm length) doped with Ca, Mn, or Cr at nominal concentrations of 0.5 and 5.0 mol% were implanted into femoral medullary canals of female rats for 16 weeks. Tissue formation within tubes was determined by histology and histomorphometry. Addition of Ca to alumina promoted hypertrophic bone formation at the advancing tissue fronts and tube entrances, and appeared to retard angiogenesis by limiting ongoing cellular migration into the tube. It is speculated that the presence of a secondary phase of calcium hexaluminate, probably having a solubility greater than that of alumina, possibly increased the level of extracellular Ca and, consequently, stimulated osteoclastic activity at the bone-ceramic interface. Addition of Mn significantly enhanced osteogenesis within the tubes. However, it is not possible to determine whether phase composition or microstructure of the ceramic was responsible for this because both were significantly altered by Mn addition. Addition of Cr to the alumina apparently stimulated bone remodelling as indicated by increased cellular activity and bone resorption at the tissue-implant interface. Cr was incorporated into the alumina as a solid solution and the tissue response was speculated to be an effect of surface chemistry rather than microstructure. The work demonstrates that doping a bioinert ceramic with small amounts of specific elements can significantly alter tissue ingrowth, differentiation, and osteogenesis within a porous implant.

Aluminum↗
PubMed1982

Successful treatment of paraquat poisoning: activated charcoal per os and "continuous hemoperfusion".

Ingestion of paraquat results in an extremely dangerous poisoning. The first aim is to clear the gastrointestinal tract by inducing emesis and performing gastric/gut lavage; as much activated charcoal as possible should be administered per os and as quickly as possible. The best measure to eliminate paraquat from blood and tissue is hemoperfusion with coated activated charcoal; it has to be performed in the sense of "continuous hemoperfusion" about 8 h/d over a period of 2-3 weeks. These measures give a chance to lower the lethality of paraquat poisoning.

Adolescent↗
PubMed1981

Paraquat poisoning - management and prognosis.

Paraquat poisoning has become a significant clinical problem since the early 1960s. Its high mortality has posed a major challenge to clinicians treating these patients. Two patients who survived and one who did not are reported. The management of these patients and the possible factors affecting their outcome are discussed.

Adolescent↗
PubMed1992

Interaction of bovine serum albumin with the surface of a microcrystalline aluminum oxide hydroxide compound: a possible new type of phosphate adsorbent.

Aluminum hydroxide gel (ALG) has been effective for ameliorating acidosis associated with phosphatemia caused by hemodialysis. However, aluminum accumulation in the body causes severe side effects. As substitute for ALG, a new type of aluminum oxide hydroxide (tentatively named PT-A) was prepared with the hope of future clinical use. PT-A has a microcrystalline structure with a high resistance to pH change and has more phosphate-binding efficacy than ALG. It was tested for possible interaction with protein by adsorption test, zeta-potential analysis, X-ray diffraction, and scanning electron microscopy. Bovine serum albumin (BSA) was chosen as a model protein. The interaction of BSA with PT-A depended on the amount of adsorbent. Protein adsorption occurred rapidly and reached the maximal level at near neutral pHs. Phosphate adsorption was not affected by the presence of BSA, but the interaction of BSA with PT-A was significantly reduced by the presence of phosphate. Zeta-potential changes on the surface of PT-A indicated that the positively charged surface of PT-A was covered with negatively charged phosphate ions that repelled negatively charged BSA molecules. X-ray diffraction patterns indicated no observable structural alteration caused by adsorption of BSA or phosphate, and scanning electron microscopy revealed that BSA covered the outer surface of PT-A but did not cover small pores, where phosphate can freely penetrate.

Adsorption↗
PubMed1983

Novel composite sorbent beads for paraquat removal by hemoperfusion.

The present report describes the development and performance of a column that is to be used for removal of paraquat from circulating blood in a hemoperfusion-type set-up. The key element of the system is a newly developed sorbent material containing fuller's earth entrapped in cross-linked agarose beads (Talosit). The technique produces a sorbent material exhibiting a very large active surface area while allowing for high mobility of paraquat molecules within the beads and favorable flow characteristics of packed column. Cross-linking of the agarose (by epichlorohydrin) also has a most beneficial effect on the mechanical strength of the beads as well as on their stability to sterilization in an autoclave. The composite beads exhibit good blood compatibility. A scanning electron microscope analysis of the beads showed no adherence of cellular blood components after contact with blood. Moreover, no significant changes in plasma composition had taken place when the beads were properly conditioned prior to contact with fresh human blood. A comparative study of paraquat removal from saline solution by the new beads and by cellulose-coated activated charcoal (Adsorba-300C) indicates a higher removal rate with the former. The results obtained so far with this new sorbent are very promising and extension of these studies to in vivo hemoperfusion is under way.

Adsorption↗
PubMed1986

Scintigraphic assessment of neorectal motor function.

Colectomy, mucosal rectectomy, and ileal pouch-anal anastomosis have become alternatives to proctocolectomy and ileostomy for patients with ulcerative colitis or polyposis coli. The aim of this study was to develop a scintigraphic technique for assessment of the "neorectal" motor function of such patients. An artificial stool, consisting of a 7.5% dispersion of aluminum magnesium silicate in water, was labeled with 1 mCi [99mTc]sulfur colloid and instilled into the neorectum. Static pre- and postevacuation scans and dynamic acquisition scans during evacuation were taken with the patient seated on a commode. The imaging provided good anatomic definition of the pouch and quantitated the usual rate and percentage of neorectal evacuation at about 10 ml stool/sec and 60% of instilled stool, respectively. This technique appeared to be a safe, simple, useful tool for assessing the neorectal motor function of patients with ileal pouch-anal anastomosis.

Adult↗
PubMed1992

27Al and 23Na double-rotation NMR of sodalites.

The 27Al NMR spectra of calcium tungstate aluminate sodalite (CAW), Ca8[Al12O24](WO4)2, and the 23Na NMR spectra of sodium aluminosilicate sodalites of general composition Na9[Si6Al6O24]A2 with A = B(OH)4- (SBS), SCN- (SRS) and A2 = SO4(2-) (SSS), MoO4(2-) (SMS) have been measured using magic-angle spinning (MAS) and double-rotation (DOR) techniques. Rotor synchronized pulse excitation is applied in the DOR experiments. Dramatic line narrowing is observed in the DOR spectra of all samples. The 27Al DOR NMR spectra of CAW measured at 9.4 and 11.7 T and spinning rates of 800-1150 Hz of the outer and 5 kHz of the inner rotor show seven sharp central lines accompanied by a manifold of spinning sidebands. These lines correspond to the seven crystallographically inequivalent Al sites of the CAW framework derived from X-ray structure analysis. From the difference of the line positions in the 9.4 and 11.7 T spectra the quadrupole coupling constant, QCC, quadrupole induced shift, sigma qs, and isotropic chemical shift, delta cs, of each Al site have been calculated. QCC values in the range of 5 to 9 MHz are obtained which reflect the strong tetragonal distortion of the AlO4 tetrahedra in CAW. delta cs shows only small changes in the range between 74.4 and 77.2 ppm. A tentative assignment of all lines to the distinct Al sites is derived from the correlation between QCC and a "shear strain parameter" describing quantitatively the distortion of the AlO4 tetrahedra.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum↗
PubMed1982

Nepheline rock dust pneumoconiosis. A report of 2 cases.

Two cases of nepheline rock dust pneumoconiosis are presented. Radiologically, this is seen as a diffuse increase in interstitial lung markings, lymphadenopathy, air-space disease, and atelectasis secondary to extrinsic compression by enlarged hilar lymph nodes. Major differential diagnoses include carcinoma of the lung, sarcoidosis, and interstitial lung disease caused by other inorganic dusts. Nepheline rock dust pneumoconiosis should be considered when the above radiological changes are observed and an occupational exposure to inorganic dust is documented.

Aluminum Compounds↗
PubMed1990

Adsorption of creatinine to Fuller's earth.

In search for a secondary reference method for the determination of creatinine, the adsorption of creatinine to seven different commercial batches of Fuller's earth have been investigated. Mineralogical investigation of the batches broadly divided them into two subgroups with quite different cation exchange capacities (CEC): dominant smectitic with and without calcium carbonate and dominant palygorskitic with calcium carbonate. Adsorption experiments using 14C-creatinine show, for all Fuller's earth samples, an incomplete adsorption of creatinine. The amount of creatinine adsorbed depends on pH, temperature, concentration of cations as Ca2+ and Na+, and other conditions. Weakly acidic suspensions of Fuller's earth in the course of time change their ability to adsorb creatinine. Compared to a synthetic strong acidic cation exchanger, Fuller's earth is more selective to creatinine. Because of the sensitivity of the adsorption to the various experimental conditions a determination of creatinine in biological fluids using Fuller's earth is too variable. Therefore, we cannot recommend this procedure as a secondary reference method for the determination of creatinine.

Adsorption↗
PubMed1983

Osteogenesis after bone and bone marrow transplantation. The ability of ceramic materials to sustain osteogenesis from transplanted bone marrow cells: preliminary studies.

The ability of four different ceramic materials to support osteogenesis when placed with bone marrow into an intermuscular site was studied. In the search for biodegradable porous ceramic materials that could be used for bone replacement and that would slowly be replaced by bone by means of "creeping substitution," the authors fabricated porous alumina, calcium aluminate, calcium hydroxyapatite, and tricalcium phosphate. Specially shaped compacts, impregnated with autologous bone marrow, were inserted into intermuscular pouches in rabbits and retrieved after 14-182 days. Newly formed bone was found within the contents of the well after 14 days and was visible at all times up to 182 days. The bone was frequently found to have adhered to the ceramic and to have penetrated the interior if the pore size was greater than 100 micron. Further investigation of the use of synthetic materials in bone replacement is warranted due to the finding that some porous ceramic material permit bony ingrowth from autologous marrow cells.

Aluminum↗
PubMed2005

Fracture surface examination of dental ceramics using fractal analysis.

OBJECTIVE: The purpose of this study was to measure the fractal dimensional increment of the fracture surface of six dental ceramics, and to measure the correlation of the fractal dimensional increment with fracture toughness. The six dental ceramics investigated were: a traditional porcelain (Finesse[F], Ceramco, Burlington, NJ, USA), four leucite reinforced pressable ceramics (Finesse Pressable [FP], Ceramco; Empress [E], Ivoclar; New Albany, NY, USA and two shades of OPC [OA2 and OI40], Jeneric-Pentron, MA, USA), and a lithium disilicate containing pressable ceramic ([LD] Ceramco). METHODS: The fracture surfaces examined and the measured fracture toughness (K(IC)) values are from a previous study . An impression was taken of the fracture surface, poured up in epoxy, coated with gold, a second layer of epoxy added, and then the surface polished at an angle to the fracture surface. This fracture interface (slit island) was observed in an optical microscope with an imaging system from which an image of the fracture line was digitized. The slit island perimeter was then measured using five different length rulers. The fractal dimensional increment (D*) was determined using a Richardson technique. A second experiment on three ceramics investigated whether there was a correlation between fracture toughness and the values of D* measured by an alternative technique using a confocal microscope. RESULTS AND SIGNIFICANCE: Fracture toughness was well correlated with D* using either technique.

Aluminum Compounds↗
PubMed1987

Treatment of paraquat poisoning in man: methods to prevent absorption.

Theoretically, absorption of an ingested dose of paraquat may be reduced by gastric lavage, induced emesis, whole-gut lavage or by the oral administration of absorbent substances. Animal experiments suggest that paraquat is absorbed poorly from the stomach and absorbed incompletely (less than 5%) from the small intestine over a 1-6 h period. Although gastric lavage would therefore seem a logical way to ameliorate the toxicity of an ingested dose of paraquat, peak plasma concentrations are attained rapidly and evidence for the efficacy of gastric lavage in man is poor. In 1977, a potent emetic (PP796) was added to liquid and solid formulations of paraquat because experiments in primates had demonstrated a fivefold reduction in toxicity. In man, ingestion of formulations containing an emetic is more likely to cause spontaneous vomiting within 30 min than non-emetic preparations. However, definite evidence of benefit, as judged by improved patient prognosis, has yet to be established. Gut lavage has been shown to remove only a small proportion of an ingested dose of paraquat. At the flow rates employed in man (75 ml/min), approximately 0.5-1.0 litres of lavage fluid/h may be absorbed across the intestinal wall. Since there is a theoretical risk of increasing paraquat absorption, the use of whole-gut lavage cannot be recommended. Bipyridilium herbicides are absorbed by soil and clay minerals, and montmorillonite in particular has been shown to be a strong binding agent in vitro. Accordingly, the use of Fuller's Earth (calcium montmorillonite) and Bentonite (sodium montmorillonite) for the treatment of poisoning has been investigated in animal models.(ABSTRACT TRUNCATED AT 250 WORDS)

Aluminum Compounds↗
PubMed1987

Paraquat poisoning.

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Aluminum Compounds↗