Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.177 (BIS)
 957 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the United States there is a new method for obtaining strong adhesive bonding between composite resins and both dentine and enamel. This experimental procedure has not reached commercial availability but several manufacturers are making preparations to supply it. The procedure comprises the sequential application of three compounds in solution. The first is an aqueous solution of ferric oxalate which conditions the dentine or enamel surface. The second is an acetone solution of a surface-active compound such as N-phenylglycine. After the acetone evaporates the excess compound is removed by the use of more solvent. The next step is the application of an acetone solution of a monomer that resembles the BIS-GMA used in composite resins but which has certain important differences. The short label for it is 'PMDM' because it is the reaction product of pyromellitic dianhydride and 2-hydroxyethylmethacrylate. When the volatile solvent quickly evaporates a thin layer of the PMDM remains on the treated dentine or enamel surface. Composite resins will then adhere strongly to these prepared surfaces, giving tensile adhesive bond strengths up to 14 MN/m2. Bond strengths of this magnitude have, on at least ten occasions, been sufficient to break pieces of dentine out of the surfaces of the extracted teeth during testing. The bond strengths to dentine obtained by this method in the laboratory are much higher than the strengths obtained with commercially available materials. The new technique is more complicated than those now in use. This creates a challenge to the dental manufacturers who must produce and supply these materials in a storage-stable form and who must provide directions that will lead to their proper use and the best results.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Bonding of restorative materials to dentine: the present status in the United States. 389 42

Three experiments were conducted to study the effect of inorganic and organic acids on survival of dialyzed bovine spermatozoa. Ejaculates were pooled, extended (1:10), dialyzed (1:50) for 2 h during cooling, and 1 h later they were frozen in pellets and stored in liquid nitrogen. The pellets were thawed in aluminum block depressions (preheated at 45 degrees C) and transferred to a test tube at room temperature as the last ice melted. Sperm motility was recorded in all samples before freezing and after thawing. The number of spermatozoa that passed through the Sephadex column was analyzed in all the postthaw samples. No statistical difference (P>0.05) was found between the use of potassium (KOH) or sodium hydroxide (NaOH) as titration bases. However, solutions containing calcium (Ca++) or magnesium (Mg++) provided significantly less (P<0.05) protection to the cells during freezing and thawing. No significant difference (P>0.05) was found in sperm survival of the postthaw samples when Ca++ or Mg++ were present. Inorganic salts of phosphates, carbonates or chloride provided significantly less protection to the cells than the control extenders with Na citrate (P<0.05). Results of the second experiment indicated that citrate, tartrate and oxalate salts provided superior (P<0.05) protection to the cells than salts of succinate, acetate or formate. It was concluded that an appropriate solution for use as a dialysate of extended bovine spermatozoa may be formulated as 30% (V/V) isosmotic Na salt of Piperazine-N-N-BIS (2-ethane sulfonic acid) (PIPES) plus 30% (V/V) isosmotic glucose plus 5% (V/V) glycerol plus 35% (V/V) of isosmotic solutions of Na or K citrate or tartrate, or a (1:1) combination of them.
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PMID:Development of a buffer system for dialysis of bovine spermatozoa before freezing. III. Effect of different inorganic and organic salts on fresh and frozen-thawed semen. 1672 21