The nasolabial angle in diagnosis.
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Cephalometry↗
Biomedical subjects
J R Heath
Publications and source records attributed to J R Heath.
Evaluation of biodegradable ampicillin anhydrate microcapsules for local treatment of experimental staphylococcal osteomyelitis.
Successful treatment of chronic osteomyelitis requires sustained high concentrations of antibiotics locally within the infected bone. The efficacy of biodegradable (poly-DL-lactide-co-glycolide) microspheres containing 30.7% ampicillin anhydrate for the local treatment of experimental staphylococcal osteomyelitis was evaluated in rabbits. In the initial experiment, antibiotic therapy was initiated immediately following injection of Staphylococcus aureus into the proximal tibial metaphysis. A single intramedullary injection of microencapsulated ampicillin (100 mg) prevented osteomyelitis in all seven animals tested and was as effective as a two-week course of parenteral ampicillin administration. When antibiotic therapy was delayed for seven days, osteomyelitis developed in four of eight animals treated locally with microencapsulated ampicillin and in six of eight animals that received parenteral ampicillin therapy. When antibiotic therapy was delayed for seven days and was preceded by debridement, all ten animals treated locally with microencapsulated ampicillin had sterile bone cultures. In contrast, seven of ten animals treated locally with unencapsulated ampicillin powder developed osteomyelitis. Biodegradable antibiotic-loaded microspheres may be of clinical benefit for the local treatment of chronic osteomyelitis.
Ampicillin↗
The C9 cluster: structure and infrared frequencies.
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Carbon↗
The C7 cluster: structure and infrared frequencies.
Observation and characterization of the C7 cluster are reported. Carbon clusters are produced by laser vaporization of a graphite target followed by supersonic expansion of the vaporized material within a gas dynamically focused argon jet. Thirty-six sequential rovibrational lines of the nu 4 antisymmetric stretch fundamental of C7 are probed by gated detection of diode laser absorption. The observed spectrum is characteristic of a symmetrical linear molecule. Analysis of the spectrum indicates an effective average bond length of 1.2736(4) angstroms and a vibrational frequency of 2138.1951(10) reciprocal centimeters, in excellent agreement with ab initio calculations. This work will facilitate the astrophysical detection of this cluster.
Argon↗
Tunable far-IR laser spectroscopy of jet-cooled carbon clusters: the nu 2 bending vibration of C3.
Seven rovibrational transitions of the (01(1)0) <-- (00(0)0) fundamental bending band of C3 have been measured with high precision with the use of a tunable far-infrared laser spectrometer. The C3 molecules were produced by laser vaporization of a graphite rod and cooled in a supersonic expansion. The astrophysically important nu 2 fundamental frequency is determined to be 63.416529(40) cm-1. These measurements provide the basis for studies of C3 in the interstellar medium with far-infrared astronomy.
Astronomy↗
Organic chemistry of C60 (Buckminsterfullerene): chromatography and osmylation.
Treatment of C60 with osmium tetroxide and pyridine gives the osmate ester (2:1 adduct) establishing that oxygen functionality can be added to C60 without disrupting the carbon framework.
Carbon↗
Pathogenic potential of Eubacterium yurii subspecies.
Several mechanisms that could contribute to the periodontopathogenic potential of Eubacterium yurii were investigated. All 18 strains examined produced RNAase and the metabolites H2S, indole and butyrate. Some strains produced phosphatase and DNAase. Methanol extracts of whole cells of E. yurii subspp. yurii and margaretiae stimulated bone resorption in vitro comparable to that produced by recognised periodontal pathogens. These results suggest that further studies should be performed to elucidate the role of E. yurii in periodontal disease.
Bone Resorption↗
Finishing composite restorative materials.
A clinically realistic in vitro study was performed to determine the best method for smoothing trimmed surfaces of seven composite restorative materials. Soflex discs produced the smoothest surface, and little advantage appeared to be gained by prior smoothing of the surface with stones or points. A polishing paste, even when used with intermediate finishing agents, produced a rougher surface than that left by the discs.
Composite Resins↗
Diode-laser absorption spectroscopy of supersonic carbon cluster beams: the nu 3 spectrum of C5.
A new spectroscopic experiment has been developed in which rovibrational transitions of supersonically cooled carbon clusters, which were produced by laser vaporization of graphite, have been measured by direct-absorption diode-laser spectroscopy. Thirty-six sequential rovibrational lines of the nu 3 band of the C5 carbon cluster have been measured with Doppler-limited resolution. The absorption spectrum is characteristic of a linear molecule with a center of symmetry. Least-squares analysis of the spectrum indicates an effective carbon-carbon bond length of 1.283 angstroms, in good agreement with ab initio quantum chemical calculations. This work confirms the detection of C5 in IRC + 10216 reported in the accompanying paper.
Astronomical Phenomena↗
A scanning electron microscopic study of in vitro toxicity of ethylene-oxide-sterilized bone repair materials.
Polylactic acid (PLA) and polyglycolic acid (PGA) have been under investigation for use in the management of hard- and soft-tissue wounds. Current research has included the incorporation of osteo-inductive substances into a PLA-PGA copolymer alloplastic implant material for enhancement of the healing of osseous defects. Conventional methods of sterilization--such as dry heat, steam heat, or 60Co--tend either to destroy or attenuate osteo-inductive activity and alter polymer biodegradation. Ethylene oxide (EO) gas sterilization is currently being tested as an alternate method. This study examined the relationship of EO-induced cytotoxicity to the length of time of polymer aeration following EO sterilization. Three groups of copolymer implant discs were studied: (1) 50:50 PLA-PGA copolymer, (2) PLA-PGA polymer with hydroxyapatite (HA), and (3) PLA-PGA with autolyzed, antigen-extracted (AA) bone particles. Polymer discs, as well as particulate HA and AA bone controls, were sterilized with EO for 12 hours. Following periods of two weeks, one week, one day, or no subsequent vacuum aeration, samples were placed into 24-well culture plates. A suspension of human fibroblasts was added to each well. Cell growth and attachment were permitted for 24 hours. Medium was then removed, and solutions for cell fixation, buffer washing, and dehydration were added to each well. SEM examination revealed changes in cell growth with increasing periods of aeration suggestive of increasing cell vitality. Cells growing on discs having no aeration were small, round, and lobulated, whereas those of seven to 14 days' aeration were more numerous, and flattened with many microvilli, pseudopodia, and dendritic processes, features consistent with normal cell morphology. These results suggest that EO-sterilized polymer implants should be aerated for least seven to 14 days prior to surgical use.
Bone and Bones↗
Simple methods for denture identification: a clinical trial.
The persistence of identification marks applied to dentures with two spirit solvent based fibre tip pens and graphite pencil covered with an experimental and a proprietary sealant were studied under service conditions. In general, the marks applied with the pens were rapidly lost, but those covered with the sealants persisted satisfactorily. The experimental sealant performed slightly better than the proprietary product.
Aged↗
Denture identification--a simple approach.
In order to find a denture identification method that could be rapidly applied to completed dentures, a variety of spirit pens and commercial and experimental sealants were investigated. The pens were generally rapidly removed by one or more abrasive, denture cleansing, antiseptic or mouthwash agent; the sealants exhibited greater longevity. An experimental sealant (acrylic polymer dissolved in chloroform) was found to be cheap, readily prepared, easily applied, very resistant to abrasion, unaffected by immersion denture cleansers, antiseptics and mouthwashes, to produce no more crazing on dentures than the other sealants investigated, and not to affect the transverse strength of acrylic resin.
Acrylic Resins↗
Reaction of human sera with Eubacterium brachy: isolation and characterization of an extracellular antigen.
Recent studies have demonstrated an association of Eubacterium sp. with the subgingival microflora of patients with chronic periodontitis. One species, Eubacterium brachy, was evaluated to determine the possible mechanisms by which this microorganism may contribute to these diseases. Of 167 sera evaluated by double diffusion in agar, 20.8% displayed reactivity with a sonicated preparation of E. brachy. An extracellular antigen was identified in the culture supernatant fluid which reacted with antibodies in human sera. This antigen was isolated by methanol precipitation and purified by gel filtration. When tested by an enzyme-linked immunosorbent assay, all sera displayed some reactivity. Lines of identity were not shared with other species of Eubacterium, but were shared with other clinical isolates of E. brachy. The reactive antibody was identified as immunoglobulin G by immunoelectrophoresis, verified by enzyme-linked immunosorbent assay, and found to be capable of complement fixation. The monosaccharides and amino acids of the extracellular antigen were identified by high-pressure liquid chromatography. This antigen was shown to have a molecular weight of 170,000 and to share a line of identity with the sonicated preparation of E. brachy. The possible role of the organism in the immunopathology of periodontal diseases is discussed.
Amino Acids↗
Maxillary control with functional appliances: some clinical observations.
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Activator Appliances↗
Association of leucogenenol, a thymothyroid hormone, with carrier proteins in the thymus.
Leucogenenol a heterocyclic enolic thymothyroid hormone (MW 383) whose concentration in the serum regulates the rate at which already committed cells of the bone marrow develop into functional cells, was found to be associated in the thymus with a carrier protein. The carrier protein for leucogenenol is not precipitated by heating to 80 degrees but following this treatment leucogenenol is precipitated in association with proteins precipitated by acetone and then by saturated ammonium sulfate. On chromatography on Sephacryl G-200 it was found that leucogenenol was associated with proteins of MW approximately 38,000. Leucogenenol is not eluted from the chromatographic column if it is not associated with its carrier proteins. It is suggested that other hormones such as those associated with the reproductive cycle or compounds that result from tissue damage induce the liberation of leucogenenol from its carrier protein in the thymus to the circulation where it is associated as previously described, with a protein of approximately MW 300,000.
Animals↗
Eubacterium brachy. Reactivity in in vitro bone resorptive bioassay.
Recent studies have demonstrated an association of Eubacterium sp. with the subgingival microflora of patients with chronic periodontitis. One species, Eubacterium brachy, was evaluated to determine the possible mechanisms by which this microorganism may contribute to this disease. An extracellular antigen was identified in the culture supernatant which reacted with antibodies in human sera. This antigen was isolated by methanol precipitation and purified by gel filtration. The purified extracellular antigen was reacted in vitro with 45CaCl2-labeled fetal rat bone in a bone resorptive bioassay. This antigen was shown to have a molecular weight of 170,000, to share a line of identity with a sonicated preparation of E. brachy whole cells and to result in increased 45CaCl2 release from fetal rat bones when cultures were exposed to the purified extracellular antigen at concentrations of 10 to 53 micrograms/ml.
Animals↗
The copy denture technique. Variables relevant to general dental practice.
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Copying Processes↗
The abrasion of acrylic resin by cleaning pastes.
The physical removal of plaque from dentures by brushing is important in the maintenance of oral health. However, there is a danger that brushing will abrade acrylic resin. A machine using a rotary brushing action was therefore utilized for laboratory tests of possible cleaning pastes, employing a toothbrush with good access and adaptability to denture surfaces. Crest toothpaste produced the most abrasion on acrylic resin, Dentu-Creme the least. An experimental paste produced an appreciably lower abrasion rate. Self-cured specimens wore more than heat-cured ones. The rate of abrasion decreased as the temperature was raised. Brushing with water alone, or with a 10% solution of soap, did not produce detectable wear. The wear produced by proprietary cleaners when hand brushing the lingual flanges of dentures and flat blanks of heat-cured acrylic was also measured. Boots denture cleaning paste produced the greatest abrasion, Dentu-Creme the least. The wear measured by reference to a glass plane was at least twice that recorded by the decrease in depth of a groove. The machine did not quantitatively produce the same abrasion as hand brushing, nor did it qualitatively rank the pastes in the same order of abrasiveness. The clinical relevance of these results is discussed.
Acrylic Resins↗