Search PubMed⌕ Search

Biomedical subjects

G Coleman

Publications and source records attributed to G Coleman.

At least 55 records · Page 3Linked to original sources
PubMed1989

A review of dental radiographic interpretation, Part II: Differential diagnosis of radiopacities, mixed radiolucent-radiopaque lesions, maxillary sinus disease, and soft tissue calcifications.

Dental radiographic interpretation requires an understanding of the wide variety of disease processes that can affect the jaws as well as features useful in the differential diagnosis of jaw lesions. Part II of this series presents an approach to the differential diagnosis of radiopaque and mixed radiolucent-radiopaque jaw lesions, maxillary sinus disease, and soft tissue calcifications.

Calcinosis↗
PubMed1989

Effect of salivary proteins on binding curves of three radioimmunoassay kits: Amerlex-M progesterone, Amerlex cortisol, and Biodata testosterone.

Radioimmunoassay (RIA) is generally used to measure certain salivary hormones because of its high sensitivity. For speed and simplicity, it has been used in the form of "direct" assays, i.e., without first extracting the analyte from its matrix. Investigating the effect of the principal salivary proteins on the binding behavior of three commercial RIA kits, we found that the Amerlex-M [125I]progesterone binding was greatly reduced when alpha-amylase and mucins were added to the binding medium, whereas IgA and IgG were less effective. The Serono Biodata [125I]testosterone binding was unaffected by proteins, while the Amerlex [125I]cortisol binding was decreased by alpha-amylase and mucins. The protein influence was largely eliminated when an extraction step was incorporated. Thus, direct RIA of saliva may be subject to matrix effects, to extents that vary with the kit and that may adversely affect the quality of the assay results.

Humans↗
PubMed1988

Ataxia telangiectasia and acinic cell carcinoma of the parotid gland.

An increased incidence of malignancies occurs in ataxia telangiectasia. These are most frequently hematopoietic in children and epithelial in adults. Both cellular immunodeficiency and chromosome damage have been implicated in their etiology. There has been only one report of a salivary malignancy, a parotid mucoepidermoid carcinoma. We describe a second salivary malignancy, a metastasizing acinic cell carcinoma of the parotid gland, that developed in a 33-yr-old woman with ataxia telangiectasia. The marked chromosomal abnormalities that were present may have been involved in the pathogenesis of her tumor.

Adult↗
PubMed1987

A comparative study of the formation of extracellular proteins by Aeromonas salmonicida at two different temperatures.

Aeromonas salmonicida was grown in a supplemented 3% (w/v) tryptone soya broth medium at 10 degrees C, a temperature at the lower end of the range over which furunculosis has been observed to occur in the field, and 25 degrees C, the optimum temperature for growth. Similar bacterial densities in the range 2.35 +/- 0.05 mg dry wt/ml were achieved in the two cultures at the beginning of the stationary phase of the growth cycle, after 125 h at 10 degrees C and 18 h at 25 degrees C. At this point, at the higher temperature 1.5 times more exoprotein was formed, 80 +/- 2.8 micrograms/ml compared with 54 +/- 1.7 micrograms/ml. Exoprotein contained the same proportion of haemolysin at both temperatures and twice as much protease at the higher temperature. The most marked difference was in an unidentified 100 kD protein which was formed in a 10-fold greater amount at 10 degrees C.

Aeromonas↗
PubMed1987

Identification of major common extracellular proteins secreted by Aeromonas salmonicida strains isolated from diseased fish.

Ten different strains of Aeromonas salmonicida that were isolated from diseased fish were grown under identical conditions (24 h at 25 degree C) in 3% (wt/vol) tryptone soya broth medium supplemented with vitamins and inorganic ions. In each case the extracellular proteins that were formed were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and it was found that there were two significant common components, one with a molecular weight of 70,000 and the other with a weight of 56,000. Application of enzyme purification techniques to the supernatant fraction proteins of a culture of one of the strains resulted in the isolation of a 70-kilodalton (kDa) component, which was found to be a serine protease, and a 56-kDa component, which was hemolytic to trout erythrocytes. Rocket immunoelectrophoresis with rabbit antibodies to the isolated protease and hemolysin showed the same antigenic components in the supernatant fractions of all the cultures. These activities were assayed, and protease activity was found to vary by a factor of three, from 59 to 195 U/ml, while the range of hemolytic activity was over a narrow band, from 28 to 43 U/ml. There was an inconsistency between the immunoelectrophoretic and direct assay data in only one case. This indicated the presence of additional hemolytic activity, in addition to the 56-kDa component. The detection of large amounts of the same protease and hemolysin, two potent degradative activities, in a random series of strains of A. salmonicida suggests that they may be obligatory virulence factors in the development of furunculosis.

Aeromonas↗
PubMed1985

Conditioned placebo responses.

Following earlier animal research, we attempt to condition placebo effects in human subjects. Four groups of 8 voluntary subjects were told that the experimenters would test a powerful new analgesic cream over three sessions by assessing its ability to reduce experimentally induced pain. The analgesic cream was, in fact, a placebo. In the first session all subjects were tested with and without the cream to assess their placebo response. In the second session, to condition two groups (with differing stimulation levels) to experience pain relief in response to the placebo, we repeatedly paired a reduction in nocioceptive stimulation with placebo administration. (Subjects were unaware that stimulation levels were manipulated). To condition the other two groups (with different stimulation levels) to experience an exacerbation of the pain, we paired an increase in nocioceptive stimulation with placebo administration. In the third session, all subjects were again tested for placebo response. Results suggested that placebo responses are conditionable in the laboratory in both a positive and negative direction. The clinical implications of a learning theory of placebo behavior are discussed.

Administration, Topical↗
PubMed1985

A comparison of the patterns of extracellular proteins produced by the high alpha-toxin-secreting organism Staphylococcus aureus (Wood 46) during aerobic and anaerobic growth.

Staphylococcus aureus (Wood 46) was grown aerobically and anaerobically in supplemented 3% (w/v) Tryptone Soya Broth medium for 24 h at 37 degrees C. Although the bacterial density achieved was 9 times higher in the aerobic culture, the exoprotein produced per unit of bacterial dry weight was only 1.4 times higher than in the anaerobic culture. However, the SDS-PAGE patterns of extracellular proteins were quite different: the aerobic products occurred almost exclusively in the mol. wt range 15-30000 compared with 30-60000 for those produced anaerobically. The only major component common to both preparations was alpha-toxin which accounted for 2.4 times more of the total exoprotein under aerobic than under anaerobic conditions.

Aerobiosis↗
PubMed1983

The effect of glucose on the differential rates of extracellular protein and alpha-toxin formation by Staphylococcus aureus (Wood 46).

The differential rates of formation of total extracellular protein and alpha-toxin by Staphylococcus aureus (Wood 46) were determined during aerobic growth, at 37 degrees C, in a complex medium containing 0.0, 0.25 or 1.0% (wt/vol) glucose. Different inocula were employed from 1% (vol/vol) of an overnight culture to 100% where bacterial cells were washed and resuspended in fresh medium without change in density. It was shown that under all conditions examined the differential rates of total extracellular protein formation exhibited a biphasic pattern characteristic of regulation based on 'competition'. This biphasic pattern was maintained even in the presence of a large inoculum and a high glucose concentration, conditions considered to favour the onset of catabolite repression. However, a lowering of the initial rate was observed with increasing glucose suggesting the superimposition of catabolite repression as a modulating effect under extreme conditions. In the case of the specific extracellular protein component, alpha-toxin, its differential rate of formation paralleled total exoprotein in all except the condition most favourable for catabolite accumulation when a deviation consistent with a pronounced catabolite repression of this component was demonstrated which was not pH-dependent.

Bacterial Proteins↗
PubMed1982

Reversal of the anti-ovulatory action of stress in rats by prior administration of naloxone hydrochloride.

Immature, 32-day-old rats were treated with PMSG. Stress consisting of 180 min immobilization administered during the period of the preovulatory LH surge resulted in the blockage of ovulation. The anti-ovulatory action of stress was effectively antagonized by the administration of naloxone hydrochloride shortly before the application of the stress, suggesting that the ovulation block by stress is mediated by endogenous opioids known to be elevated during stress. Blockage of ovulation by 180 min immobilization stress occurred only in rats from one of the two laboratory strains tested, suggesting that stress resistance is, at least in part, genetically determined.

Animals↗
PubMed1981

Ultrastructure of hydrated proteoglycans using a pulsed plasma source.

During the past 10 years, attempts have been made to examine hydrated biological specimens by using wet chambers (at ambient temperature) [1-3] or cold stages (at -30 degrees C and below) during electron microscopic examination. Obtaining sufficient contrast of unstained hydrated biological samples has proven a considerable problem using both of these methods. Many fragile biological specimens, when examined hydrated, frozen or dried, are severely damaged by the electron beam and cannot be imaged by conventional scanning or transmission electron microscopy. In order to increase specimen contrast and eliminate electron beam induced trauma to the specimen, we have developed a wet-cell [4], which when used in concert with a pulsed plasma soft X-ray source, provides high contrast contact replicas of totally hydrated, unstained biological specimens. Although it has been postulated that hydrated unstained samples can be imaged by soft X-ray contact microscopy [5-7], to date there has been little success due to cell movement or degradation of the wet sample during the long exposure period necessary for an adequate imaging dose [8]. With the pulsed plasma source described in this study we have been able to use exposure times of approximately 40-60 ns while maintaining the sample in its hydrated state at atmospheric pressure. The resultant contact replicas exhibit good contrast and better than 30 nm spatial resolution when examined by conventional scanning electron microscopy.

Chemical Phenomena↗
PubMed1981

Pleiotropic compensation in the regulation of extracellular protein formation by a low alpha-toxin-producing variant of Staphylococcus aureus (Wood 46).

The changes in bacterial density, total extracellular protein and haemolysin produced by bacteria from overnight cultures of Staphylococcus aureus (Wood 46) and a low alpha-toxin-producing variant suspended in fresh medium were followed at 37 degrees C. Although five extracellular proteins were produced at a reduced level by the variant (alpha-toxin formation was reduced more than tenfold), the differential rates of total extracellular protein formation by the two organisms were identical. The results are consistent with a common regulatory mechanism for extracellular protein formation in which a pleiotropic compensation may occur in order to saturate the extracellular protein-producing capability.

Bacterial Proteins↗
PubMed1980

Persistence of rat nocturnal feeding and drinking during diurnal presentation of palatable diet.

Male laboratory rats were fed a highly palatable diet during the light phase of a 12:12 LD cycle. Nocturnality of feeding was reduced from approximately 77% of the total daily intake to 56%. Increase in diurnal feeding was attributable to the ingestion of a large meal at the beginning of the L phase. Reduction of nocturnal feeding was attributable to decreased ingestion in the first 3 hr of the D phase. Outside these times the daily feeding pattern was unmodified. These findings do not represent a reversal of the feeding rhythm as previously reported, but a modification which is not consistent with interpretation as a phase-shift. Throughout the testing period total daily food intake remained unchanged and body weight was defended despite the increase in calories ingested. Daily drinking patterns and total daily water intake were not significantly altered by the experimental manipulation.

Animals↗
PubMed1980

Food and water deprivation: changes in rat feeding, drinking, activity and body weight.

Groups of male rats totally food deprived for periods up to 96 hr, water ad lib do not totally regain body weight lost through deprivation. Degree of body weight defence was estimated by fitting statistically a curve to the predeprivation baseline data and extrapolating the curve over the deprivation and postdeprivation period. From group data, body weight is not fully defended. However, marked individual differences in degree of body weight defence were noted. During food deprivation the daily drinking cycle persists for approximately 48 hr, then a reduction in nocturnal drinking appears. General activity increases but only in the light period. After food restitution, the main hyperphagia is confined to the first post-deprivation day. Additional, subtle long term effects of overeating in the light period are also found. In contrast to food deprived groups, water deprived groups accurately defend body weight. During water deprivation daily food intakes decrease immediately whereas nocturnal activity decreases after approximately 72 hr of deprivation has elapsed. After the termination of water deprivation the immediate response is gross hyperdipsia, but again subtle long term effects are apparent. Total daily food intake increases for many days but the increase is not confined to either light or dark periods. Water intake is similarly affected. These results are evaluated in relation to the notion of a body weight set-point regulating feeding behavior. Some limitations on the value of the findings in terms of species differences and lack of ecological validity are also discussed.

Animals↗