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Biomedical subjects

E C Williams

Publications and source records attributed to E C Williams.

47 records · Page 3Linked to original sources
PubMed1985

Evaluation of three bacteriuria screening methods in a clinical research hospital.

In a study conducted to compare three screening methods for their ability to detect significant bacteriuria, 2,815 urine specimens were screened by Chemstrip LN (BioDynamics, Division of Boehringer Mannheim Chemicals, Indianapolis, Ind.), 1,000 were screened by Bac-T-Screen (Marion Scientific Laboratory, Kansas City, Mo.), and 289 were screened by ATP assay (Turner Designs, Mountain View, Calif.). Results were compared with those obtained by quantitative culture plate method. The ATP assay showed the highest sensitivity (91%) compared with the Bac-T-Screen (67%) and Chemstrip LN (50%) tests but had the lowest specificity (64%) compared with the Bac-T-Screen (83%) and Chemstrip LN (91%). In 101 leukopenic patients with significant bacteriuria, the Bac-T-Screen test showed a higher sensitivity (33% at 10(4) to 10(5) CFU/ml and 80% at greater than or equal to 10(5) CFU/ml). It is concluded from this study that none of the three methods are sufficiently sensitive for the clinical research patients in this institution.

Adenosine Triphosphate↗
PubMed1984

The effect on dentine permeability of time following cavity preparation in dogs.

Cavities were prepared into the dentine of mandibular first molars of anaesthetized dogs. Conical plastic chambers were cemented into the cavities to permit quantitation of dentine permeability using a fluid-filtration technique. There was a progressive fall in dentine permeability every hour for the 6 h of study, to about 20 per cent of zero time values. The fall in dentine permeability could be delayed but not prevented, by filtering fluid across the dentine into the pulp. Similar experiments on teeth from which the pulps had been removed showed no change or a slight increase in permeability with time. No change in dentine permeability was seen in dogs killed after the zero time measurement and followed for an extra 6 h. This decrease of dentine permeability in response to cavity preparations only occurs in teeth with intact pulps.

Animals↗
PubMed1983

The effects of acid etching on the in-vivo permeability of dentine in the dog.

Cavities were cut in both lower molars of 11 anaesthetized dogs. Dentine permeability was quantitated in these teeth using a filtration technique before and after acid etching to remove the smear layer. Acid-etching increased 5-fold the ease with which fluid could flow across dentine. Under conditions of high fluid filtration, an opening into the pulp chamber from the opposite side of the tooth produced only slight increases in filtration rate, indicating that the rate-limiting step is filtration of fluid across dentine, rather than removal of the fluid by the pulp circulation.

Acid Etching, Dental↗
PubMed1983

Progressive decrease in dentine permeability following cavity preparation.

Dentine permeability determinations were made longitudinally in cavities prepared in dog teeth in vivo, using two different techniques: isotope clearance and fluid filtration. Measurements made with both techniques indicate that there is a large reduction in dentine-permeability within the first week following cavity preparation. The phenomenon requires an intact pulp and is not the result of microleakage of temporary restorations.

Animals↗
PubMed1983

Species identification and antibiotic susceptibilities of coagulase-negative staphylococci isolated from clinical specimens.

Identification of potentially significant coagulase-negative staphylococci isolated from clinical specimens was performed along with antibiotic susceptibility determinations, S. epidermidis accounted for 75% of these isolates, with S. haemolyticus and S. hominis being the second and third most frequently encountered species, respectively. Although there were many instances of single blood culture isolations of questionable significance, all three species were also found in multiple blood cultures from individual patients, indicating the ability to cause significant bacteremia. The most common source for most species was blood, except for S. saprophyticus and S. simulans, which were found more frequently in urine. Of urinary tract isolates, however, S. epidermidis was more common than S. saprophyticus. Antibiotic susceptibility profiles demonstrated that S. haemolyticus and S. epidermidis were frequently multiply antibiotic resistant. S. haemolyticus had a higher percentage of isolates that were oxacillin, cephalothin, aminoglycoside, erythromycin, and clindamycin resistant than did S. epidermidis. We found that species identification could be of benefit for both epidemiological as well as patient care purposes, and that this additional information is readily available, using convenient and rapid new methods.

Anti-Bacterial Agents↗
PubMed1982

Conformational states of fibronectin. Effects of pH, ionic strength, and collagen binding.

Human plasma fibronectin was enzymatically labeled with dansylcadaverine using plasma Factor XIIa. Fluorescence polarization studies of dansylcadaverine-labeled fibronectin indicate that fibronectin has a significant degree of chain flexibility in physiologic solution and that there is an increase in chain flexibility at high pH or ionic strength. Binding of a collagen peptide to dansylcadaverine-fibronectin results in a decrease in fluorescence polarization, suggesting that such binding causes a conformational change which also results in increased chain flexibility.l Quasielastic light scattering and intrinsic viscosity measurements of fibronectin were performed under physiologic conditions and at high pH and ionic strength. Shape calculations based on these data indicate that fibronectin is in an elongated configuration under physiologic conditions and further unfolds at high pH or ionic strength into a very flexible, strand-like configuration. Light scattering studies of fibronectin after binding of a collagen fragment indicate that such binding results in a decrease in the diffusion coefficient, suggesting that collagen binding also results in a partial unfolding of fibronectin. These results suggest that published electron micrographs of fibronectin showing a long, strand-like molecule do not reflect the conformation of plasma fibronectin under physiologic conditions; fibronectin, however, may assume an unfolded conformation upon binding to collagen in the tissue matrix.

Cadaverine↗
PubMed1977

Construction of an automated health problem inventory.

An Automated Health Problem Inventory was designed to monitor resident exposure, provide access to subgroups of the patient population, allow for study of patient care patterns over time, and aid in health-care evaluation studies. Major design steps such as choosing data and codes are discussed. Data collection documents and data reports are described. Data were collected over a 12-month period in two clinical settings - a model clinic in a residency program and a private practice clinics. These data are displayed by categories of problems and frequency of individual problems. The authors comment on the human and procedural support needed to make a data system useful.

Electronic Data Processing↗
PubMed1976

Natural abundance carbon-13 nuclear magnetic resonance studies of bovine white matter and myelin.

Whole bovine white matter yields a poorly resolved natural abundance 13C nuclear magnetic resonance (NMR) spectrum. The spectrum principally reflects carbon atoms of the constituent membrane lipids: several resonances could be specifically assigned but no resonances attributable to cholesterol are detectable. Except for the methyl group at the terminus of fatty acyl chains, lipid carbons giving rise to the 13C NMR spectrum have values of spin-lattice relaxation time between 140 and 500 ms, indicating significant restrictions on segmental and rotational mibolities but consistent with a generally fluid structural organization. The 13C NMR spectrum of myelin isolated from bovine white matter is similar to that for the whole white matter itself. In both white matter and isolated meylin, the integrated intensities for several carbon atoms are considerably less than those for the same carbon atoms in total lipid extracts. The data for white matter and myelin are consistent with a model in which observed line broadening is due to restrictions in the amplitude of chain flexing rather than to severe restrictions on chain segmental motion. Failure to detect resonances of cholesterol ring system carbon atoms may reflect marked anisotropy of rotational reorientation.

Animals↗