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At least 1,261 records · Page 70Linked to original sources
PubMed1980

Inhibition of hepatitis B virus specific DNA polymerase by intercalating agents.

Intercalating agents, some of them in clinical use, were tested for their ability to inhibit the hepatitis B virus specific DNA polymerase reaction. Ethidium bromide was shown to be the strongest inhibitor among the compounds tested. Compounds in clinical use inhibited the DNA polymerase test only at high concentrations. The inhibitory activity of all compounds tested was increased when the MgCl2 content in the reaction mixture was lowered. UV absorption studies presented no evidence that this effect was due to complex formation of magnesium and the individual compounds. The therapeutic significance of these findings is not certain and needs further work.

Carrier State↗
PubMed2006

The determination of phosphorus containing compounds in dental casting investment products by 31P solid-state MAS-NMR spectroscopy.

OBJECTIVES: To use (31)P solid-state MAS-NMR to determine the phosphorus compounds that occur in dental casting investment material: (a) as-received, (b) after setting and (c) after burn-out and discover whether such compounds are the same in each material across a product range. METHODS: [(1)H] High powered decoupling (HPDC) and [(1)H] cross-polarization (CP) (31)P solid-state MAS-NMR spectroscopy at a resonance frequency of 121.4 MHz were used. Six commercial products were examined. Manufacturer's instructions were followed and a special liquid was used without dilution. RESULTS: All products contain ammonium dihydrogen phosphate as the acid phosphate required for the setting reaction. All set by the formation of struvite and significant amounts of amorphous magnesium orthophosphate. In three products, lesser amounts of newberyite were present and in another the equivalent amorphous compound was formed. When burnt-out, magnesium metaphosphate or pyrophosphate was the dominant matrix compound. A higher burn-out temperature favoured pyrophosphate formation. Farringtonite was present to a lesser extent with the metaphosphate. SIGNIFICANCE: Compounds that were not detected in earlier X-ray powder diffraction spectroscopy studies were detected by NMR, notably amorphous and glassy compounds (magnesium orthophosphate in set investment and magnesium metaphosphate in burnt-out material). The variation between products was significant and far greater than expected from the published scientific literature. Since the formation of compounds is affected by technical procedure and ambient conditions, these findings could offer some insight into the cause of the unpredictability of expansion measurements between laboratories. Further research is being undertaken.

Dental Casting Investment↗
PubMed2004

A combination of riboflavin, magnesium, and feverfew for migraine prophylaxis: a randomized trial.

OBJECTIVE: To determine the efficacy for migraine prophylaxis of a compound containing a combination of riboflavin, magnesium, and feverfew. BACKGROUND: Previous studies of magnesium and feverfew for migraine prophylaxis have found conflicting results, and there has been only a single placebo-controlled trial of riboflavin. DESIGN/METHODS: Randomized double-blind placebo-controlled trial of a compound providing a daily dose of riboflavin 400 mg, magnesium 300 mg, and feverfew 100 mg. The placebo contained 25 mg riboflavin. The study included a 1-month run-in phase and 3-month trial. The protocol allowed for 120 patients to be randomized, with a preplanned interim analysis of the data after 48 patients had completed the trial. RESULTS: Forty-nine patients completed the 3-month trial. For the primary outcome measure, a 50% or greater reduction in migraines, there was no difference between active and "placebo" groups, achieved by 10 (42%) and 11 (44%), respectively (P=.87). Similarly, there was no significant difference in secondary outcome measures, for active versus placebo groups, respectively: 50% or greater reduction in migraine days (33% and 40%, P=.63); or change in mean number of migraines, migraine days, migraine index, or triptan doses. Compared to baseline, however, both groups showed a significant reduction in number of migraines, migraine days, and migraine index. This effect exceeds that reported for placebo agents in previous migraine trials. CONCLUSION: Riboflavin 25 mg showed an effect comparable to a combination of riboflavin 400 mg, magnesium 300 mg, and feverfew 100 mg. The placebo response exceeds that reported for any other placebo in trials of migraine prophylaxis, and suggests that riboflavin 25 mg may be an active comparator. There is at present conflicting scientific evidence with regard to the efficacy of these compounds for migraine prophylaxis.

Double-Blind Method↗
PubMed1997

In vitro attachment of osteoblast-like cells to osteoceramic materials.

OBJECTIVE: The objective of this work was to examine osteoblast-like cell attachment and morphology in vitro to osteoceramic materials with three different surface morphologies. METHODS: Osteoceramic composite disks were fabricated from tricalcium phosphate and magnesium-aluminate spinel (MgAl2O4) in a 50 vol% ratio. The disks were prepared with three different surface morphologies, including as-fired (irregular), etched (rough), or polished through 1 mm diamond paste (smooth). Osteoblast-like cell cultures were plated onto the prepared disks for 2 h, and the number of attached cells was determined. ANOVA and Student Newman-Kuels tests were used to test for significant differences in cell attachment (p < 0.05). SEM was used to visually evaluate the nature of the cellular adaptation on the osteoceramic surfaces. RESULTS: Some additional surface roughening resulted from the interaction between the osteoceramic disks and the biological culture media during the attachment assay. A statistically larger number of cells was found to be attached to the etched osteoceramic surfaces compared to the as-fired and polished osteoceramic surfaces or the tissue culture plastic control. Cellular adaptation was extensive on all three osteoceramic surfaces at 2 h. SIGNIFICANCE: These results are consistent with previous in vivo work and continue to support the hypothesis that osteoceramic materials have potential for implants and bone substitute materials.

Aluminum Compounds↗
PubMed1998

Metal chloride primers for bonding dentine with tri-n-butylborane-initiated luting agents.

OBJECTIVES: The bonding of resin to dentine is dependent largely on surface modifications. The purpose of the present study was to test the hypothesis that a role of the metal chlorides used as primers is to initiate polymerization of resin at the resin-dentine interface, thereby affecting bond strength. METHODS: Nine primers were evaluated, comprising aqueous 2-hydroxyethyl methacrylate (HEMA) solutions containing AICl3, CeCl3, CoCl2, CuCl2, FeCl3, NiCl2, MgCl2, SnCl2 or ZnCl2, respectively. One of the two luting agents (Super-Bond resin) consisted of methyl methacrylate (MMA), 4-methacryloyloxyethyl trimellitate anhydride (4-META) and tri-n-butylborane (TBB) initiator. The other luting agent (MMA-TBB resin) consisted of MMA and TBB without 4-META. Extracted bovine teeth were ground to expose the dentine, etched with an aqueous solution of 10% phosphoric acid, primed, and then bonded with stainless-steel rods; tensile bond strengths were determined after 1-day immersion in water. Data were analysed by ANOVA and Duncan's new multiple range test (P < 0.05). RESULTS: Four of the metal chlorides (CuCl2, FeCl3, MgCl2 and ZnCl2) enhanced the bond strengths of MMA-TBB resin to dentine. With Super-Bond resin, maximum bond strengths of 15.6 MPa and 19.0 MPa were recorded with primer containing 2.0 x 10(-5) mol g(-1) FeCl3 and 2.0 x 10(-6) mol g(-1) CuCl2, respectively. CONCLUSIONS: Bonding techniques, combining the use of either cupric primer or ferric primer with 10% phosphoric acid etchant may be suitable for application in seating resin-bonded prostheses with TBB-initiated luting materials.

Acid Etching, Dental↗
PubMed1980

Dissolution of vesical calculi with Renacidin in a paraplegic man.

Vesical calculi are common in spinal cord injury patients. The majority are composed of magnesium ammonium phosphate, a compound readily soluble in the solvent Renacidin. We describe a paraplegic man with recurrent bladder stones in whom cystolitholopaxy was unsuccessful. His calculi were completely dissolved by continuous Renacidin bladder irrigation. We recommend Renacidin for the initial treatment of vesical calculi in selected spinal cord injury patients. Many such stones will completely dissolve and others may be made softer or smaller, facilitating cystolitholopaxy. A significant number of patients will be spared the inconvenience, cost and morbidity of hospitalisation for a surgical procedure.

Adult↗
PubMed2004

Magnesium-induced copper-catalyzed synthesis of unsymmetrical diaryl chalcogenide compounds from aryl iodide via cleavage of the Se-Se or S-S bond.

The methodology for a copper-catalyzed preparation of diaryl chalcogenide compounds from aryl iodides and diphenyl dichalcogenide molecules is reported. Unsymmetrical diaryl sulfide or diaryl selenide can be synthesized from aryl iodide and PhYYPh (Y = S, Se) with a copper catalyst (CuI or Cu(2)O) and magnesium metal in one pot. This reaction can be carried out under neutral conditions according to an addition of magnesium metal as the reductive reagent. Furthermore, it is efficiently available for two monophenylchalcogenide groups generated from diphenyl dichalcogenide.

Journal Article↗
PubMed2006

Stereoselective syntheses of piperidinones and their modification by organometallic coupling reactions.

Dehydropiperidinones stereoselectively obtained from N-arabinosyl imines were iodinated at the enaminone structure. Knochel iodine-magnesium exchange afforded Grignard compounds of these piperidinone derivatives which reacted, either directly or after transmetalation to zinc or copper intermediates, with alkyl-, aryl- or acylhalides to give correspondingly substituted piperidinones. Stereoselective conjugate allyl cuprate addition to a thus obtained 5-allyl dehydropiperidinone and ring-closing metathesis of the product gave a hydroquinolinone containing three stereogenic centers.

Chemistry, Organic↗
PubMed1995

Effects of a Dan Shen component, magnesium lithospermate B, in nephrectomized rats.

Magnesium lithospermate B, a compound newly isolated from Dan Shen, was given orally to rats for 70 days after excision of five-sixths of their kidney volume. As a result, mesangial proliferation, tubulo-interstitial lesions and glomerular sclerotic lesions, which were conspicuous in rats that were not given magnesium lithospermate B after nephrectomy, were inhibited. Furthermore, a decrease in blood urea nitrogen, improvement of hypoproteinemia, hypoalbuminemia and hypercholesteremia, and inhibition of urinary protein excretion were observed. The levels of creatinine, methylguanidine and guanidino-succinic acid, which accumulate in the blood with the progress of renal failure, were decreased significantly in rats given magnesium lithospermate B. These results indicate that magnesium lithospermate B, a component of an Oriental medicine has potential as a new therapeutic agent for inhibiting the progression of renal dysfunction.

Animals↗