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At least 1,549 records · Page 86Linked to original sources
PubMed2003

Effect of aromatics on lung mucociliary clearance in patients with chronic airways obstruction.

BACKGROUND: Complementary and alternative medicine have become an increasingly topical theme in respiratory medicine. Aromatics are a commonly used ingredient in a number of proprietary medicines. It is well established that lung mucus clearance is impaired in patients with chronic airways obstruction. This study investigated whether aromatics delivered by inunction could be objectively shown to enhance lung clearance. METHODS: We studied 12 patients with chronic bronchitic with a mean standard error (SE) age of 67 (2) years (mean [SE] tobacco consumption history of 64 [12] pack-years). We used a randomized, single-blinded, placebo-controlled crossover trial within patient design assessing the effect of 7.5 g of aromatics inunction (compared to a "no-treatment baseline" and to a petrolatum "placebo") on lung mucus clearance measured by a standard radioaerosol technique. RESULTS: Aromatic treatment significantly enhanced clearance at two time points 30 (p < 0.05) and 60 (p < 0.02) minutes postradioaerosol inhalation but had no demonstrable further effect over the following 5 hours despite further application of the inunction. The clearance improvement (relative to a baseline) observed during the first hour of testing was significantly correlated (p < 0.01) with the concentration level of aromatics. CONCLUSION: Our data, thus, provide objective evidence of a positive effect of aromatics inunction on mucus clearance in chronic airways obstruction.

Aged↗
PubMed2004

Rubbing ointments and asthma morbidity in adolescents.

OBJECTIVE: To determine the relationship between the use of rubbing ointments and asthma morbidity in adolescents. DESIGN: Cross-sectional study. SETTINGS/LOCATION: Inner-city high school in the Bronx, New York. SUBJECTS: 165 adolescents with asthma. OUTCOME MEASURES: Asthma morbidity, defined as emergency department (ED) use for asthma in the past year and over the lifetime. RESULTS: While 127 (77%) of subjects used albuterol as the first treatment for their last asthma attack, 18 (11%) used rubbing ointments. The rubs and albuterol groups were similar in asthma severity, mean age, gender, and ethnicity. However, subjects in the the rubs group were less likely than subjects in the albuterol group to have made an ED visit over the past 12 months or over their lifetime. Regression analysis revealed that, after controlling for asthma severity, use of rubs independently predicted less lifetime ED use. CONCLUSIONS: After controlling for asthma severity, use of rubs by adolescents with asthma was associated with lower asthma morbidity as measured by ED use.

Adolescent↗
PubMed2000

Examination of the enantiomeric distribution of certain monoterpene hydrocarbons in selected essential oils by automated solid-phase microextraction-chiral gas chromatography-mass selective detection.

A viable approach for the determination of sources of essential oils based on automatic injection solid-phase microextraction-chiral-gas chromatography-mass selective detection is demonstrated. With no sample preparation, it is shown that the source of essential oils such as peppermint, spearmint, and rosemary can be easily distinguished. Short fiber exposure times of approximately 6 s to the headspace above submicroliter quantities of the selected oils are all that is required to obtain both the required sensitivity and resolution to afford analyses with excellent reproducibilities (relative standard deviation values consistently less than 5.0%).

Autoanalysis↗
PubMed1991

A predicted three-dimensional structure of human cytochrome P450: implications for substrate specificity.

A three-dimensional structure for human cytochrome P450IA1 was predicted based on the crystal coordinates of cytochrome P450cam from Pseudomonas putida. As there was only 15% residue identity between the two enzymes, additional information was used to establish an accurate sequence alignment that is a prerequisite for model building. Twelve representative eukaryotic sequences were aligned and a net prediction of secondary structure was matched against the known alpha-helices and beta-sheets of P450cam. The cam secondary structure provided a fixed main-chain framework onto which loops of appropriate length from the human P450IA1 structure were added. The model-built structure of the human cytochrome conformed to the requirements for the segregation of polar and nonpolar residues between the core and the surface. The first 44 residues of human cytochrome P450 could not be built into the model and sequence analysis suggested that residues 1-26 formed a single membrane-spanning segment. Examination of the sequences of cytochrome P450s from distinct gene families suggested specific residues that could account for the differences in substrate specificity. A major substrate for P450IA1, 3-methyl-cholanthrene, was fitted into the proposed active site and this planar aromatic molecule could be accommodated into the available cavity. Residues that are likely to interact with the haem were identified. The sequence similarity between 59 eukaryotic enzymes was represented as a dendrogram that in general clustered according to gene family. Until a crystallographic structure is available, this model-building study identifies potential residues in cytochrome P450s important in the function of these enzymes and these residues are candidates for site-directed mutagenesis.

Amino Acid Sequence↗
PubMed1993

Engineering cytochrome P-450cam to increase the stereospecificity and coupling of aliphatic hydroxylation.

Site-directed mutants were constructed in cytochrome P-450cam to re-engineer the stereochemistry and coupling of ethylbenzene hydroxylation. The reaction with wild-type (WT) enzyme produces one regioisomer 1-phenylethanol with 5% reduced nicotinamide adenine deoxyribonucleic acid to product conversion of and a ratio of 73:27 for the R and S enantiomers respectively. Ethylbenzene was modeled into the active site of WT P-450cam in a rigid mode and oriented to optimize either pro-R or pro-S hydrogen abstraction. Residues T101, T185 and V247 make extensive contacts with the substrate in the static complexes and were therefore chosen for site-directed mutagenesis. Single mutants T101M, V247A and V247M are more stereospecific producing 89, 87 and 82% (R)-1-phenylethanol respectively. The coupling of the reaction is doubled for the single mutants T185L, T185F and V247M. In an effort to engineer increased stereospecificity and coupling into a single catalyst the T101M, T185F and V247M mutants were combined in a multiple mutant of P-450cam. This protein hydroxylates ethylbenzene resulting in an R:S ratio of 87:13 for the 1-phenylethanols and 13% coupling of reducing equivalents to product. The catalytic stereospecificity and stoichiometry with T101M--T185F--V247M does not represent a summation of the changes observed for the single mutants. A portion of the individual effects on substrate recognition produced by the single substitutions is either eliminated or degenerate within the triple mutant.

Benzene Derivatives↗
PubMed1994

A study of simulated annealing protocols for use with molecular dynamics in protein structure prediction.

The method of simulated annealing can be of use in protein structure prediction by homology modelling where side chain conformations must be predicted. In this study an attempt has been made to optimize a molecular dynamics method for this purpose. Heating and cooling protocols to maximize the accuracy of the predictions have been developed. The optimized protocol involves cooling from 3000 to 0 K over 20 ps while simultaneously introducing the non-bonded energy term. The use of a 'soft' non-bonded interaction energy term in place of a standard 6-12 potential is found to be important. The reliability of the predictions has been analysed in terms of the environment of the residues (solvent accessibility) and the degree of uncertainty in the structure (number of unknown torsion angles). Depending on these factors the percentage of unknown side chain torsion angles that are correctly predicted within 30 degrees ranges from approximately 50 to 75%. Potential problems and limitations of the method are discussed.

Amino Acid Sequence↗
PubMed1995

Enzyme-catalyzed dehalogenation of pentachloroethane: why F87W-cytochrome P450cam is faster than wild type.

Under anaerobic conditions, cytochromes P450 can reductively dehalogenate heavily halogenated hydrocarbons, such as one- and two-carbon organic solvents. This catalytic capacity has drawn attention to the potential use of engineered forms of P450s in the remediation of contaminated deep subsurface ecosystems. Loida (1994, PhD Thesis, University of Illinois at Urbana-Champaign, IL) and S.G. Sligar (personal communication) have observed recently that an active-site variant of cytochrome P450cam (F87W) dechlorinates pentachloroethane approximately three times faster than the wild-type enzyme. Molecular dynamics simulations have revealed that the mutant enzyme binding pocket remains smaller, and that pentachloroethane assumes configurations closer to the heme-Fe in the F87W mutant twice as often as in the wild-type enzyme. This result is consistent with a collisional model of dehalogenation, which agrees with experimental observations [Li and Wackett (1993) Biochemistry, 32, 9355-9361] that solutions containing wild-type P450cam dehalogenate pentachloroethane 100 times faster than those containing free heme. The simulations suggest that it is unlikely that Trp87 significantly stabilizes the developing negative charge on the substrate during carbon-halogen bond reduction. The design of improved microbial enzymes that incorporate both steric and electronic effects continues for use in remediating halogenated contaminants in situ.

Binding Sites↗
PubMed1996

Construction and evaluation of a three-dimensional structure of cytochrome P450choP enzyme (CYP105C1).

The purpose of this work was to develop and carefully evaluate improved strategies for constructing reliable 3-D models of P450 isozymes. To this end, a unique combination of steps for building and evaluating a model structure was used to build a homology model of the P450choP isozyme, based on knowledge of the X-ray structures of P450cam, P450terp, P450BM-3 and P450eryF. Specifically, the reliability of this model was examined by systematic comparisons of its conformational, energetic, environmental and packing properties and those of the four reference proteins with corresponding properties from the database of proteins with known structures. The results showed that the examined properties of this model structure are well within the criteria established for reliable structures and are of nearly as good quality as those of the reference proteins. In addition, the result from a 120 ps unconstrained MD simulation of the model with structural waters provided evidence that the model is stable at room temperature. This 3-D model can now be reliably used for explicit characterization of substrate and inhibitor complexes. Most importantly, although it is envisioned that building models for mammalian P450s will be even more challenging, the steps described here should be very useful in future construction of 3-D models of mammalian P450 isozymes.

Amino Acid Sequence↗
PubMed2002

Incidence of postoperative pain after intracanal procedures based on an antimicrobial strategy.

The purpose of this prospective study was to evaluate the incidence of postoperative pain after intracanal procedures based on an antimicrobial strategy. Data were examined from 627 teeth that had necrotic pulps or required retreatment. Information was obtained for each patient treated with regard to presence of preoperative pain. Occurrence of periradicular bone destruction detected by radiographs was also recorded. The operators consisted of undergraduate students, who were in their first year of clinical training. Root canals were instrumented and then medicated with a calcium hydroxide/camphorated paramonochlorophenol paste. No systemic medication was prescribed. Approximately 1 week after the initial appointment, patients were asked about the occurrence of postoperative pain and the level of discomfort was rated as no pain, mild pain, moderate pain, or severe pain. Data were statistically analyzed using the Chi-square test. Mild pain occurred in 10% of the cases, moderate in 3.3%, and severe (flare-up) in 1.9%. Postoperative pain was significantly associated with the treatment of previously symptomatic teeth without periradicular lesions (p < 0.01). No other correlations were detected between the occurrence of postoperative discomfort and other clinical conditions. There was also no difference regarding the incidence of postoperative pain between treatment and retreatment (p > 0.01). The intracanal procedures used in this study to control root canal infections showed a small incidence of postoperative pain, particularly flare-ups, even performed by inexperienced undergraduate dental students.

Adolescent↗
PubMed2002

Microbial susceptibility to calcium hydroxide pastes and their vehicles.

The aim of this study was to investigate the susceptibility of some microorganisms commonly isolated from root canals to calcium hydroxide in combination with several vehicles by the agar diffusion method. Stainless-steel cylinders were placed on each inoculated agar medium. The test medications and their controls were placed inside the cylinders. The zones of growth inhibition were measured and recorded after the incubation period for each plate, and the results were analyzed statistically. Enterococcus faecalis was most resistant, whereas the anaerobic Porphyromonas endodontalis was more susceptible to all medications, followed by P. gingivalis and Prevotella intermedial intermedia. Ca(OH)2 + CMCP + glycerin showed significantly larger mean zones of inhibition when compared with the other medications. We conclude that anaerobic Gram-negative bacteria are more susceptible to calcium hydroxide pastes than facultative Gram-positive microorganisms.

Actinomyces↗
PubMed2003

Elimination of Candida albicans infection of the radicular dentin by intracanal medications.

Fungi have been associated with cases of secondary or persistent root canal infections. The purpose of this study was to evaluate the effectiveness of four intracanal medications in disinfecting the root dentin of bovine teeth experimentally infected with Candida albicans. Infected dentin cylinders were exposed to four different medications: calcium hydroxide/glycerin; calcium hydroxide/0.12% chlorhexidine digluconate; calcium hydroxide/camphorated paramonochlorophenol/glycerin; and 0.12% chlorhexidine digluconate/zinc oxide. Specimens were in contact with the medications for 1 h, 2 days, and 7 days. The viability of C. albicans after exposure was evaluated by specimen incubation in culture medium to compare the effectiveness of the medications in disinfecting dentin. Results showed that the specimens treated with calcium hydroxide/camphorated paramonochlorophenol/ glycerin paste or with chlorhexidine/zinc oxide paste were completely disinfected after 1 h of exposure. Calcium hydroxide/glycerin paste only consistently eliminated C. albicans infection after 7 days of exposure. Calcium hydroxide mixed with chlorhexidine was ineffective in disinfecting dentin even after 1 week of medication exposure. Among the medications tested, the calcium hydroxide/camphorated paramonochlorophenol/glycerin paste and chlorhexidine digluconate mixed with zinc oxide were the most effective in eliminating C. albicans cells from dentinal specimens.

Animals↗
PubMed1993

Predicting the cytochrome P450 mediated metabolism of xenobiotics.

The cytochrome P450s play a unique role in the metabolism of xenobiotics. Characteristics which allow a vast number of foreign compounds to be metabolized by a limited number of enzymes include broad substrate specificity and broad regioselectivity. Because of their importance in both the metabolism and toxicity of drugs and environmental contaminants, efforts are being made to use computational methods to predict these biotransformation pathways. This review describes the recent progress towards the prediction of the tertiary structures of the various P450s and the determination of the electronic characteristics of substrates which determine their tendency to be oxidized by the P450s.

Amino Acid Sequence↗