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)

Most commercial dental composites contain liquid dimethacrylate monomers (including BIS-GMA or variations of it) and silica-containing compositions as inorganic reinforcing filler particles coated with methacrylate-functional silane coupling agents to bond the resin to the filler. They also contain initiators, accelerators, photo-initiators, photosensitizers, polymerization inhibitors, and UV absorbers. Durability is a major problem with posterior composites. The typical life-span of posterior composites is from three to 10 years, with large fillings usually fewer than five years. Polymerization shrinkage and inadequate adhesion to cavity walls are remaining problems. Some pulp irritation can occur if deep restorations are not placed over a protective film. Some have advocated the use of glass-ionomer cement as a lining under resin composite restorations in dentin. The concept of glass-ionomer cements (GICs) was introduced to the dental profession in the early 1970's. Current GICs may contain poly(acrylic acid) or a copolymer. Higher-molecular-weight copolymers may also be used to improve the physical properties of some GICs. Stronger and less-brittle hybrid materials have been produced by the addition of water-soluble compatible polymers to form light-curing GIC formulations. The ion-leachable aluminosilicate glass powder, in an aqueous solution of a polymer or copolymer of acrylic acid, is attacked by the hydrated protons of the acid, causing the release of aluminum and calcium ions. Salt bridges are formed, and a gel matrix surrounds the unreacted glass particles. The matrix is adhesive to mineralized tissues. Provisions must be made for maintenance of the water balance of restorations for the first 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Dental composites/glass ionomers: the materials. 129 62

Calcium metaphosphates (CMP's)--a unique class of phosphate minerals possessing polymeric structures, [Ca(PO3)2]n, and having refractive indices of approximately 1.54-1.59-- are optically compatible with resins such as BIS-GMA. In this study, several types of CMP's were prepared and evaluated for their potential as fillers for visible-light-activated (VLA) dental composites. The vitreous (V) and beta-crystalline forms of CMP were prepared by controlled thermolysis of monocalcium phosphate monohydrate, Ca(H2PO4)2.H2O. Hybrid fillers were also prepared by thermal methods. Fillers, characterized by IR spectroscopy and optical microscopy, were prepared in several size ranges (e.g., 1-100 microns). VLA composites were formulated by use of both untreated and surface modified CMP's. V-CMP and its hybrids yielded composites which expanded when stored in water but were of low strength, e.g., diametral tensile strength, (DTS) = 8 MPa. beta-CMP composites were more moisture-resistant, had higher DTS's (from 12 to 33 MPa), and showed a tendency to arrest brittle fracture. These novel fillers have potential uses in resin-based materials such as dental composites, cements, and adhesives.
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PMID:Filler systems based on calcium metaphosphates. 193 40

The effects of intermittent low doses (1.25 mug daily, administered intravenously for 6 days and withdrawn for 14 days for 3 complete cycles) of 1,25-dihydroxycholecalciferol (1,25-[OH](2)D(3)) on cortical bone were determined and compared in ribs with steady state and regionally accelerated remodeling in adult intact female dogs. The bone changes were analyzed by dynamic bone histomorphometric methods, using tetracycline and DCAF (2,4 BIS) N, N' di (carboxymethyl) (amino methyl fluorescein) in vivo double labeling of bones before treatment and after 60 days of intermittent 1,25-(OH)(2)D(3) administration. Serum calcium and phosphorus levels increased during 1,25-(OH)(2)D(3) administration. Urinary hydroxyproline excretion increased during the first interval of 1,25-(OH)(2)D(3) administration but was not changed significantly during the last two intervals. In normal cortical bone (11th rib) following the administration of 1,25-(OH)(2)D(3) there was a marked decrease in the activation frequency, bone formation rate, osteoid seam thickness, seam circumference, and mean appositional rate. Although recruitment of new remodeling sites was decreased after 1,25-(OH)(2)D(3), previously existing remodeling units continued to completion. These effects resulted in a preponderance of mature osteons in normal cortical bone. The morphometric changes in cortical bone (9th rib) exposed to both 1,25-(OH)(2)D(3) and periosteal elevation were characterized by a marked increase in both the activation frequency and bone formation rate and associated with a decrease in the osteon formation time. Other morphometric parameters that were increased included radial closure rate, numbers of osteoid seams and resorption cavities, ratio of bone resorbing to forming sites, percentage labeled and circumference of osteoid seams, and total and cortical bone areas. The combined effect of periosteal elevation and 1,25-(OH)(2)D(3) were markedly different from those observed with 1,25-(OH)(2)D(3) alone. These findings suggest that the rapid bone turnover induced by tissue injury will mask or alter the effects of hormones on bone remodeling when studied over a relatively short period of time.
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PMID:Histomorphometric evaluation of the effects of intermittent 1,25-dihydroxycholecalciferol administration on cortical bone remodeling in adult dogs. 689 23

In this study two types of bioactive bone cement containing either MgO-CaO-SiO2-P2O5-CaF2 glass (type A) or glass-ceramic powder (type B) were made to evaluate the effect of the crystalline phases on their mechanical and biological properties. Type A bone cement was produced from glass powder and bisphenol-a-glycidyl methacrylate (BIS-GMA) resin, and type B from glass-ceramic powder containing apatite and wollastonite crystals and BIS-GMA resin. Glass or glass-ceramic powder (30, 50, 70, and 80 by wt %) was added to the cement. The compressive strength of type A (153-180 MPa) and B (167-194 MPa) cement were more than twice that of conventional polymethylmethacrylate (PMMA) cement (68 MPa). Histological examination of rat tibiae showed that all the bioactive cements formed direct contact with the bone. A reactive layer was seen at the bone-cement interface. In specimens with type A cement the reactive layer consisted of two layers, a radiopaque outer layer (Ca-P-rich layer) and a relatively radiolucent inner layer (low-calcium-level layer). With type B cement, although the Ca-P-rich layer was seen, the radiolucent inner layer was absent. Up to 26 weeks there was progressive bone formation around each cement (70 wt %) and no evidence of biodegradation. The mechanical and biological properties of the cements were compared with those of a previously reported bone cement containing MgO-free CaO-SiO2-P2O5-CaF2 glass powder (designated type C).
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PMID:Mechanical and biological properties of two types of bioactive bone cements containing MgO-CaO-SiO2-P2O5-CaF2 glass and glass-ceramic powder. 878 9

1. The regulation of large conductance calcium- and voltage-activated potassium (BK) currents by activation of the protein kinase C (PKC) and glucocorticoid signalling pathways was investigated in AtT20 D16:16 clonal mouse anterior pituitary corticotroph cells. 2. Maximal activation of PKC using the phorbol esters, 4beta-phorbol 12-myristate, 13-acetate (PMA), phorbol 12, 13 dibutyrate (PDBu) and 12-deoxyphorbol 13-phenylacetate (dPPA) elicited a rapid, and sustained, inhibition of the outward steady-state voltage- and calcium- dependent potassium current predominantly carried through BK channels. 3. The effect of PMA was blocked by the PKC inhibitors bisindolylmaleimide I (BIS; 100 nM) and chelerythrine chloride (CHE; 25 microM) and was not mimicked by the inactive phorbol ester analogue 4alpha-PMA. 4. PMA had no significant effect on the 1 mM tetraethylammonium (TEA)-insensitive outward current or pharmacologically isolated, high voltage-activated calcium current. 5. PMA had no significant effect on steady-state outward current in cells pre-treated for 2 h with 1 microM of the glucocorticoid agonist dexamethasone. Dexamethasone had no significant effect on steady-state outward current amplitude or sensitivity to 1 mM TEA and did not block PMA-induced translocation of the phorbol ester-sensitive PKC isoforms, PKCalpha and PKCepsilon, to membrane fractions. 6. Taken together these data suggest that in AtT20 D16:16 corticotroph cells BK channels are important targets for PKC action and that glucocorticoids inhibit PKC signalling downstream of PKC activation.
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PMID:Glucocorticoid block of protein kinase C signalling in mouse pituitary corticotroph AtT20 D16:16 cells. 1020 Apr 23

To investigate the mechanisms by which phorbol esters potentiate transmitter release from mossy fibre terminals we used fura dextran to measure the intraterminal Ca2+ concentration in mouse hippocampal slices. A phorbol ester, phorbol 12,13-diacetate (PDAc), potentiated the field excitatory postsynaptic potential (fEPSP) slope. PDAc also enhanced the stimulation-dependent increase of [Ca2+]i in the mossy fibre terminal (Delta[Ca2+]pre). The magnitude of the PDAc-induced fEPSP potentiation (463+/-57% at 10 microM) was larger than that expected from the enhancement of Delta[Ca2+]pre (153+/-5%). The Delta[Ca2+]pre was suppressed by omega-agatoxin IVA (omega-AgTxIVA, 200 nM), a P/Q-type Ca2+ channel-specific blocker, by 31%. The effect of PDAc did not select between omega-AgTxIVA-sensitive and -resistant components. The PDAc-induced potentiation of the fEPSP slope was partially antagonized by the protein kinase C (PKC) inhibitor bisindolylmaleimide I (BIS-I, 10 microM), whereas the Delta[Ca2+]pre was completely blocked by BIS-I. Although the BIS-I-sensitive fEPSP potentiation was accompanied by a reduction of the paired-pulse ratio (PPR), the BIS-I-resistant component was not. Whole-cell patch clamp recording from a CA3 pyramidal neuron in a BIS-I-treated slice demonstrated that PDAc (10 microM) increased the frequency of miniature excitatory postsynaptic currents (mEPSCs, 259+/-33% of control) without a noticeable change in their amplitude (102+/-5% of control). These results suggest that PKC potentiates transmitter release by at least two distinct mechanisms, one Delta[Ca2+]pre dependent and the other Delta[Ca2+]pre independent. In addition, some phorbol ester-mediated potentiation of synaptic transmission appears to occur without activating PKC.
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PMID:Re-evaluation of phorbol ester-induced potentiation of transmitter release from mossy fibre terminals of the mouse hippocampus. 1111 4

The proinflammatory mediator bradykinin (BK) is suggested to play an important role in the pathogenesis of various inflammatory diseases including periodontitis. In this study, BK per se stimulated interleukin-8 (IL-8) production in human gingival fibroblasts in vitro. Furthermore, BK upregulated the stimulatory effect of the cytokines IL-1beta and TNFalpha on the production of IL-8. The stimulatory effect of BK on the IL-1beta- or TNFalpha-stimulated IL-8 production was reduced in the presence of BK B2 receptor antagonist HOE 140, whereas the B1 receptor antagonist Lys-(des-arg9, Leu8)-BK had no effect. Similar to BK, the calcium ionophore A23187 also upregulated the stimulatory effect of IL-1beta and TNFalpha on IL-8 production. The protein kinase C (PKC) inhibitor bisindolylmaleimide, BIS, significantly reduced the stimulatory effect of BK on IL-1beta and TNFalpha increased IL-8 production but did not affect the production of IL-8 stimulated by cytokines alone. The specific p38 mitogen-activated protein kinase (MAPK) inhibitor SB 203580 reduced IL-8 production stimulated by the combination of BK and IL-1beta as well as the IL-1beta-stimulated IL-8 production. In conclusion, this study shows that BK upregulates IL-1beta- and TNFalpha-stimulated IL-8 production via BK B2 receptor and that PKC signal pathway seems to be involved in the upregulation of the cytokine-induced IL-8 production in gingival fibroblasts. This stimulatory effect of BK on IL-8 production may contribute to the maintenance of the gingival inflammation and enhanced risk for destruction of gingival connective tissue.
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PMID:Bradykinin upregulates IL-8 production in human gingival fibroblasts stimulated by interleukin-1beta and tumor necrosis factor alpha. 1566 65

Hypocretins are crucial for the regulation of wakefulness by the excitatory actions on multiple subcortical arousal systems. To date, there is little information about the direct postsynaptic excitatory effects of hypocretins on the neurons in prefrontal cortex (PFC), which is important for higher cognitive functions and is correlated with level of wakefulness. In this study, we tested the excitatory effects of hypocretin-1 on acutely isolated PFC pyramidal neurons of rats and studied the possible ionic mechanisms by using whole-cell patch-clamp techniques. Puff application of hypocretin-1 caused a dose-dependent excitation. Further observations that perfusion of Ca2+-free artificial cerebrospinal fluid did not influence the depolarizing effects of hypocretin-1, in conjunction with the findings that hypocretin-1 could decrease net whole-cell K+ currents, demonstrate that the excitatory effects of hypocretin-1 on PFC neurons are mediated by the inhibition of K+ currents but not Ca2+ influx. Finally, the decrease in K+ currents induced by hypocretin-1 was abolished by a protein kinase C (PKC) inhibitor (BIS II) or a phospholipase C (PLC) inhibitor (D609), suggesting that PKC and PLC appear to be involved in mediating the inhibitory effects of hypocretin-1 on K+ currents. These results indicate that hypocretin-1 exerts a postsynaptic excitatory action on PFC neurons through the inhibition of K+ currents, which probably results from activation of PKC and PLC signaling pathways.
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PMID:Postsynaptic excitation of prefrontal cortical pyramidal neurons by hypocretin-1/orexin A through the inhibition of potassium currents. 1624 2

Water samples were collected from wells (9 Nos.), springs (11 Nos.) and rivers/streams (6 Nos.) during pre and post monsoon seasons in the months of June and October 1999, respectively. Various physico-chemical parameters and trace elements (viz., Cu, Mn, Zn, Co, Fe, Ni, Cr and Pb) were analysed to evaluate drinking water quality on the basis of BIS and irrigation water quality on the basis of salinity, sodicity, residual sodium carbonate, and concentration of toxic elements. The study showed alkaline nature of surface and ground water. Calcium and magnesium are dominating cations and bicarbonate is major anion in the study area. At some locations the concentration of TDS, Mg, Ca, total hardness, Fe, Mn and Cr exceeded the limits set up for drinking purposes. Water quality evaluation for irrigation purposes on the basis of SAR values indicates excellent category of water.
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PMID:Water quality aspects of some wells, springs and rivers in parts of the Udhampur District (J & K). 1666 31

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


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