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Biomedical subjects

L J Boucher

Publications and source records attributed to L J Boucher.

At least 19 recordsLinked to original sources
PubMed1990

Radiographic examination of edentulous mouths.

Many dentists routinely make radiographs of edentulous patients who request replacement dentures. In the American Dental Associations' Guide to Dental Health, the public is informed that "an x-ray examination is performed only when necessary, not as a routine procedure, and only when the dentist believes such an examination will benefit your health." In light of the changing patterns of the incidence of disease and the cumulative effects of radiation exposure, a study was made of 300 edentulous ridges of dental patients. The study was confined to patients who were treated elsewhere with maxillary and mandibular dentures and who requested new dentures. Patients who had some clinically apparent finding that required radiographic investigation were excluded from the study. Only one impacted tooth that required extraction was found. The diagnosis of edentulous patients seeking treatment with replacement dentures should include a thorough patient history and clinical examination. When radiographs are indicated, they should be made but their routine use in such patients should be discouraged.

Aged↗
PubMed1989

Partial characterization of an enzyme that hydrolyzes sarin, soman, tabun, and diisopropyl phosphorofluoridate (DFP).

The properties of a rat liver enzyme that hydrolyzes organophosphorus (OP) inhibitors of cholinesterases were studied. The rates of hydrolysis of OP inhibitors were determined by continuous titration of released hydrogen ions, using a pH stat method. Centrifugation of homogenates at 205,000 g for 30 min demonstrated that the activity was in the soluble fraction. Hydrolysis of sarin, soman, and diisopropyl phosphorofluoridate (DFP), but not of tabun, was stimulated by the addition of Mn2+ and Mg2+. Hydrolysis of sarin greater than soman greater than tabun greater than DFP. Unlike other OP hydrolases that preferentially hydrolyze the non-toxic isomers of soman, this enzyme hydrolyzed all four soman isomers at approximately the same rate. This result was obtained in vitro by gas chromatographic analysis of enzyme-catalyzed soman hydrolysis and confirmed in vivo by demonstrating reduced toxicity in mice of soman partially hydrolyzed by this enzyme. Km and Vmax were determined by fitting V vs [S] to a hyperbolic function using regression analysis. Km values ranged from 1.1 mM for soman to 8.9 mM for tabun. Vmax values ranged from 54 nmol/min/mg protein for DFP to 2694 for sarin. The enzyme was stable for at least 2 months at -90 degrees but was inactivated by heating at 100 degrees for 5 min. Elution profiles from gel filtration by high pressure liquid chromatography showed that the hydrolytic activity for the OP inhibitors eluted in a single peak, suggesting that a single enzyme was responsible for the observed hydrolysis. Further purification and characterization of this enzyme should prove useful for the development of methods for detection, detoxification, and decontamination of these cholinesterase inhibitors.

Animals↗
PubMed1988

Specific soman-hydrolyzing enzyme activity in a clonal neuronal cell culture.

An enzymatic activity that specifically hydrolyzes the highly toxic organophosphorus anticholinesterase compound soman (pinacolyl methylphosphonofluoridate) has been identified and partially characterized in the clonal neuronal neuroblastoma-glioma hybrid NG108-15 cell line. Using the whole cell homogenate as the enzyme source and 1 mM substrate, the relative rate of hydrolysis of two other toxic anticholinesterase compounds sarin (isopropyl methylphosphonofluoridate) and tabun (ethyl-N-dimethyl phosphoramidocyanidate) is approximately one-tenth the rate of hydrolysis of soman, while DFP (diisopropyl phosphorofluoridate), paraoxon (p-nitrophenyl diethylphosphate), and a phosphinate PNMPP (p-nitrophenyl methyl (phenyl) phosphinate) are not hydrolyzed. Analysis of the kinetics of soman hydrolysis reveals two components of the enzyme activity with different affinities and reaction rates. Unlike previously reported enzymes of this type, this enzyme lacks chiral specificity and thus hydrolyzes both toxic and non-toxic soman stereoisomers at equal rates. The enzyme activity is stable at low temperature, found almost exclusively in the soluble fraction of these cells, and enhanced significantly by Mn2+ and by chemical differentiation of these cells in culture. The results suggest possible application of this enzyme for soman detection and/or detoxication, and use of the NG108-15 cell line to study the natural function(s) of enzymes of this type.

Animals↗
PubMed1984

Osteoporosis in postmenopausal women.

Eleven postmenopausal complete denture patients participated in a study to evaluate some possible predictors of osteoporosis. Most participants in the study reported a low caloric intake and consumed considerably less than the recommended daily allowances of sodium, cholesterol, calcium, fluoride, magnesium, zinc, and folic acid. Many participants in the study were taking additional daily vitamin and mineral supplements. The CCT as measured on radiographs of the second phalynx of the fifth digit of the right hand correlated linearly with the CBD corrected for soft tissue. Panoramic radiographs revealed that all individuals had severe residual ridge resorption. All serum calcium and phosphorus means were within the normal range, while more than 60% of the patients had below normal plasma levels of 25-hydroxyvitamin D. In conclusion, although based on a small sample, it appears that the diet of elderly women in New York is somewhat deficient for adequate skeletal homeostasis. Ideally, the vitamin D status of each patient should be determined and proper supplements prescribed. However, the high cost of analysis suggests that dietary analysis be used on a selected but more frequent basis. Radiation techniques for measuring skeletal porosity are also too complex to perform on a routine basis and should, like dietary analysis, be reserved for patients in whom other clinical signs and symptoms indicate metabolic bone disease.

Aged↗
PubMed1984

Removal of overhanging amalgam: a comparative study of three instruments.

This study compared the effects on tooth surface of three power-driven instruments commonly used to remove overhanging amalgam. Comparisons of methods of instrumentation were made on enamel, cementum, and amalgam. Cavitron, Roto Pro, and EVA system instruments were used. Findings showed significantly more abrasion on all surfaces in EVA groups compared with other groups. All surfaces in Roto Pro groups appeared to be smoother than in other groups. There appeared to be little difference between treated surfaces and control surfaces in the Cavitron group.

Dental Amalgam↗
PubMed1984

Professionalism.

Explore the source record for details and available documents.

Dentistry↗
PubMed1975

Resonance raman spectra of manganese (III) tetraphenylporphin halides.

Unique resonance Raman spectra were obtained when manganese(III) tetraphenylporphin halides in noncoordinating solvents were illuminated by laser frequencies around 500 nm. Of particular interest is the observation of a feature that is sensitive to the nature of the axial ligand. This feature disappears when the coordinating solvent pyridine is employed, and it, therefore, appears to be diagnostic of the manganese coordination number.

Benzene Derivatives↗