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At least 793 records · Page 44Linked to original sources
PubMed1992

The polycationic compound gentamicin inhibits the calcium paradox in guinea-pig hearts.

The polycationic drug gentamicin and two calcium antagonists were studied with respect to their protecting action against the calcium paradox in perfused guinea-pig hearts. Besides the mechanograms the release of creatine kinase was recorded; in parallel experiments the Na(+)-content of the hearts was measured before and at the end of the Ca(2+)-lack period, and during re-exposure to normal [Ca2+]0. The calcium paradox was induced by perfusion, for 50 s, with Ca(2+)-free solution containing EGTA (3 x 10(-4) M). Nifedipine and verapamil in concentrations which reduced the equilibrium contractile force by 50%, only mitigated the extent of the calcium paradox, whereas gentamicin applied in a concentration also reducing the contractile amplitude by 50% was able to suppress the calcium paradox completely. The dose-response curves for nifedipine, with respect to the reduction of contractile force and contracture, were identical. In contrast, gentamicin was more effective in attenuating the contracture of the paradox than in reducing the equilibrium contractile force. The large gain of Na+ during the Ca(2+)-lack period was diminished by both nifedipine and gentamicin. The partial protection of calcium antagonists can be related to their interference with the uptake of Na+ through L-type Ca(2+)-channels during the Ca(2+)-lack period, whereas gentamicin seems to act by an additional inhibition of the Na/Ca exchange during the re-exposure to normal [Ca2+]0.

Animals↗
PubMed2005

Effect of different dye solutions on the evaluation of the sealing ability of Mineral Trioxide Aggregate.

Alkaline materials have shown incompatibility with methylene blue dye in leakage experiments. The goal of the present study was to analyze the effect of different dyes on the evaluation of the apical sealing ability of Mineral Trioxide Aggregate root-end fillings. Fifty-six extracted human canines were submitted to root canal instrumentation and obturation. After apical resection, retrograde cavities were prepared and teeth were randomly divided into four experimental (n = 13) and two control groups (n = 2). The following root-end filling materials were used: groups 1 and 2--Pro Root MTA (Dentsply), groups 3 and 4--zinc oxide-eugenol cement (ZOE). Teeth in groups 1 and 3 were immersed in 2% methylene blue solution, while teeth in groups 2 and 4 were immersed in 0.2% rhodamine B in a reduced pressure environment for 48 hours. Teeth were then longitudinally sectioned and leakage was evaluated. Results were submitted to statistical analysis (ANOVA and Tukey's test). Group 1 presented the least leakage (p < 0.05). It was concluded that the evaluation of the sealing ability of MTA is influenced by the dye used, since this material presented better sealing ability when evaluated with Methylene Blue, but was similar to ZOE when evaluated with rhodamine B.

Aluminum Compounds↗
PubMed1997

Erucic acid and erucic acid anilide-induced oxidative burst in human polymorphonuclear leukocytes.

Human polymorphonuclear leukocytes (PMNL) were exposed to erucic acid or erucic acid anilide to explore their effects on the production of reactive oxygen species (ROS) and the levels of free intracellular calcium. The compounds did not change the levels of intracellular calcium, but both dose-dependently induced respiratory burst in PMNL. Maximal production of ROS by erucic acid exceeded that induced by its anilide 13-fold. A protein kinase C inhibitor, Ro 31-8220, completely inhibited erucic acid and erucic acid anilide-induced production of ROS. Neither erucic acid nor erucic acid anilide modified FMLP-induced production of ROS. However, erucic acid (500 microM) amplified 5 nM PMA-induced ROS production 1.8-fold, but did not have this effect at a lower PMA concentration. On the contrary, erucic acid anilide inhibited PMA-induced oxidative burst, and shifted the peak ROS production induced by PMA to a later time-point. The present results show that aniline moiety modifies the effects of erucic acid on the activation of PMNL, and suggest that both erucic acid and erucic acid anilide may activate PMNL through a protein kinase C-dependent mechanism.

Anilides↗
PubMedDate not supplied

Comparison of mineral trioxide aggregate and formocresol as pulp-capping agents in pulpotomized primary teeth.

PURPOSE: The aim of this study was to use clinical, radiographic, and histologic examinations to compare the relative success of gray mineral trioxide aggregate (MTA), white MTA, and formocresol as pulp dressings in pulpotomized primary teeth. METHODS: Twenty-four children, each with at least 3 primary molars requiring pulpotomy, were selected for this study's clinical and radiographic portion. An additional 15 carious primary teeth planned for serial extraction were selected for this study's histologic portion. All selected teeth were evenly divided into 3 test groups and treated with pulpotomies. Gray MTA was used as the pulp dressing for one third of the teeth, white MTA was the dressing for one third, and the remaining one third were treated with formocresol. The treated teeth selected for the clinical and radiographic evaluations were monitored periodically for 12 months. The treated teeth selected for histologic study were monitored periodically and extracted 6 months postoperatively. RESULTS: Four children with 12 pulpotomized teeth failed to return for any follow-up evaluations in the clinical and radiographic study. Of the remaining 60 teeth in 20 patients, 1 tooth (gray MTA) exfoliated normally and 6 teeth (4 white MTA and 2 formocresol) failed due to abscesses. The remaining 53 teeth appeared to be clinically and radiographically successful 12 months postoperatively. Pulp canal obliteration was a radiographic finding in 11 teeth treated with gray MTA and 1 tooth treated with white MTA. In the histologic study, both types of MTA successfully induced thick dentin bridge formation at the amputation sites, while formocresol induced thin, poorly calcified dentin. Teeth treated with gray MTA demonstrated pulp architecture nearest to normal pulp by preserving the odontoblastic layer and delicate fibrocellular matrix, yet few inflammatory cells or isolated calcified bodies were seen. Teeth treated with white MTA showed a denser fibrotic pattern, with more isolated calcifications in the pulp tissue along with secondary dentin formation. CONCLUSIONS: Gray MTA appears to be superior to white MTA and formocresol as a pulp dressing for pulpotomized primary teeth.

Aluminum Compounds↗
PubMedDate not supplied

Renal osteodystrophy in children on CAPD: a prospective trial of 1-alpha-hydroxycholecalciferol therapy.

The efficacy of 1 alpha-hydroxycholecalciferol in the prevention of renal osteodystrophy in children commencing continuous ambulatory peritoneal dialysis was studied in 12 patients, 0.8-17 years of age, who were randomly assigned to either group I receiving standard therapy or to group II receiving in addition 10-20 ng/kg body weight/day of 1 alpha-hydroxycholecalciferol. Calcium carbonate compounds were used to control hyperphosphataemia. Mean plasma calcium (total and ionised) and phosphate levels were not significantly different between the two groups. All group I patients continued to have elevated plasma immunoreactive parathyroid hormone levels at 6 months compared to only 1 patient in group II (p less than 0.05). Four patients in group I developed subperiosteal erosions on radiography compared to the healing of mild lesions in 2 patients in group II. Bone histomorphometry on iliac crest needle biopsy specimens revealed a significant reduction in osteoid index and seam width in group II. Serum aluminum levels decreased during the course of continuous ambulatory peritoneal dialysis, and the significant staining for bone aluminum in 6 patients at the beginning of the study was no longer present in 5 patients at 6 months. Our data demonstrate that 1 alpha-hydroxycholecalciferol is beneficial in the prevention and treatment of bone disease in children on continuous ambulatory peritoneal dialysis.

Adolescent↗
PubMed1995

Mineral trioxide aggregate: a review of a new cement.

The most common materials in endodontics are gutta-percha and sealer. For certain tasks, however, such as repairing perforations or filling apical preparations, a special-purpose material is needed. The "ideal" special-purpose material in endodontics is still elusive. Most of the materials available today have found their way into endodontics from the restorative field without much consideration of the special conditions and requirements of the periradicular tissues. To address some of the these shortcomings, a material called Mineral Trioxide Aggregate cement (MTA) has been developed at Loma Linda University to seal off the pathways of communication between the root canal system and the external surface of the tooth. At LLU, a series of experiments have been conducted to assess the suitability of this new cement. The experiments began with physical properties of the material and biocompatability studies, followed by clinical studies. The results have been promising, offering for the first time the possibility of regeneration rather than just repair.

Aluminum Compounds↗
PubMed1989

Activation and release of enzymes and major basic protein from guinea pig eosinophil granulocytes induced by different inflammatory stimuli and other substances. A histochemical, biochemical, and electron microscopic study.

In order to investigate the availability and release of enzymes from eosinophilic granulocytes in response to a variety of stimuli, guinea pig peritoneal eosinophils were obtained after repeated intraperitoneal injections of freeze-dried Trichinella spiralis larvae. The activities of the enzymes peroxidase, arylsulfatase B, beta-glucuronidase, aminopeptidase, histaminase, cytochrome c oxidase, acid phosphatase, adenosine triphosphatase and glucose 6-phosphatase, and the major basic protein (MBP) were studied histochemically and, in part, also biochemically. Eosinophils were incubated with the following substances: histamine, platelet activating factor, calcium ionophore, compound 48/80, leukotriene B4, prostaglandins E1, and E2, heparin, and eosinophil-chemotactic factors from neutrophils and lymphocytes. Eosinophils displayed a selective and stimulus-dependent enzyme and MBP reaction. Calcium ionophore and compound 48/80 provoked a release of cytotoxic major basic protein, partly associated with peroxidase release, while leukotriene B4 and eosinophil chemotactic factors caused histaminase and peroxidase release and activated leucinaminopeptidase. Heparin and calcium ionophore induced release of both MBP and histaminase. These data support the concept that eosinophils exhibit either inflammatory or cytotoxic, or antiinflammatory properties upon stimulation by various agents.

Animals↗
PubMed1988

Conformational analysis of lipoxin A, lipoxin B and their trans-isomers.

Lipoxin A and lipoxin B (LXA and LXB) are formed from the oxygenation of arachidonic acid by interactions between the 5- and 15-lipoxygenases of human leukocytes. Each compound displays highly stereospecific biological actions. Here, we present a computational description of the following compounds: lipoxin A, (5S,6R,15S)-trihydroxy-7,9,13-trans-11-cis-eicosatetraenoic acid; 11-trans-lipoxin A, (5S,6R,15S)-trihydroxy-7,9,11,13-trans-eicosatetraenoic acid; lipoxin B, (5S,14R,15S)-trihydroxy-6,10,12-trans-8-cis-eicosatetraenoic acid; and 8-trans-lipoxin B, (5S,14R,15S)-trihydroxy-6,8,10,12-trans-eicosatetraenoic acid. The analyses considered van der Waals energy, electrostatic interactions, torsional potential, and alterations in electrostatic forces. Additional analyses were carried out with each of the four compounds forming complexes with one calcium ion. Each compound gave very different conformers. Both lipoxin A and lipoxin B can form globular conformations, while their all-trans isomers form rigid extended structures. When complexes with each of these compounds and one calcium ion were examined (i.e., (LXA)2Ca: (11-trans-LXA)2Ca), both LXA and LXB formed several flexible conformations including crumpled, wrapped or extended conformations. In this situation, LXA showed a higher probability than LXB to wrap around one Ca2+. In contrast, the two all-trans isomers always lead to extended conformations. Results from the present study illustrate that changes in the stereochemistry of LXA and LXB lead to unique conformations which may underlie the different biological actions of these compounds. Moreover, they indicate that the conformations of eicosanoids can change while in aqueous or hydrophobic environments (i.e., biomembranes).

Arachidonate 15-Lipoxygenase↗
PubMed1985

Development of early post-ischemic injury in the liver as evaluated by a double staining method combining an intravital dye exclusion test and alizarin red S.

The early development of post-ischemic cell injury was investigated in rat livers. Rats were subjected to 90 minutes of liver ischemia, followed by periods of re-perfusion from 10 minutes to 3 hours. The ischemia-induced injury was quantified by using a double staining method. An intravital dye exclusion test with Evans blue was combined with a histochemical stain for calcium, Alizarin red S (ARS). It was found that the markers identified two populations of injured cells, positive for Evans blue (EBA) and ARS respectively. The number of injured cells increased successively during the re-perfusion period. The overlapping between the two populations was small during the early post-ischemic phase but increased with increasing re-perfusion time. Treatment with ruthenium red, a blocker of mitochondrial calcium uptake, during the re-perfusion period significantly reduced the number of ARS-positive cells, while the number of EBA-positive cells was not affected. It is suggested that the two markers used identify cell populations, which are injured by different mechanisms operating in the post-ischemic phase. These mechanisms may or may not be dependent on calcium.

Animals↗
PubMedDate not supplied

Sedative action of some substituted benzylamides.

Substituted benzylamide derivatives of amino acylamide (compound A,B,C, & D) were found to be less potent local anaesthetics than lignocaine and procaine. However, the four compounds exhibited sedation without ptosis and reduced spontaneous locomotor activity better than methaqualone. Compound A alone antagonised methylamphetamine induced hypermotor activity. The test compounds potentiated hexobarbitone induced hypnosis. Three compounds antagonised calcium induced stoppage of isolated heart of frog. Except compound C all caused a transitory fall of blood pressure in dog which was not blocked either by atropine or propranolol. These compounds showed neuromuscular blockade and possessed slight analgesic activity but were devoid of anticonvulsant and tranquillizing activity. LD 50 values were calculated to be 164.1 +/- 23.0, 229.1 +/- 51.0, 181.6 +/- 28.18 and 416+/-38.2 mg/kg for compounds A,B,C & D respectively.

Amides↗
PubMed2006

Antibody-conjugated soybean oil-filled calcium phosphate nanoshells for targetted delivery of hydrophobic molecules.

Hollow calcium phosphate nanoparticles capable of encapsulating poorly water-soluble molecules were produced by self-assembly. Previously reported were solid calcium phosphate nanoparticles and water-filled calcium phosphate nanocapsules suited for encapsulating mostly hydrophilic, but not hydrophobic compounds. Here, calcium phosphate was deposited around 100 nm diameter, 1,2-dioleoyl-sn-glycero-3-phosphate stabilized soybean oil nanoemulsions using either calcium chloride or NaOH titrations to achieve shell thickness between 20-70 nm. The surface was functionalized with carboxylic acid via the addition of carboxyethylphosphonic acid to attach Molecular Probes AB-594C antibody using sulpho-n-hydroxysuccinimide and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride with an efficiency of approximately 70%, while retaining near complete antibody function. Hydrophobic pyrene was encapsulated with an efficiency of 95%, at concentrations much higher than its water solubility limit, and exhibited spectral features characteristic of a hydrophobic environment. These materials can be used in the targeted delivery of many useful, yet poorly water-soluble pharmaceutical and nutraceutical compounds.

Antibodies↗