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Biomedical subjects

M Wilson

Publications and source records attributed to M Wilson.

At least 451 records · Page 25Linked to original sources
PubMed1993

Nicotine effects on eicosanoid formation and hemostatic function: comparison of transdermal nicotine and cigarette smoking.

OBJECTIVES: The purpose of this study was to examine the possible role of nicotine in enhancing coagulation and to assess the potential cardiovascular toxicity of transdermal nicotine therapy for smoking cessation. BACKGROUND: Cigarette smoking increases the risks of acute coronary events. A likely contributing mechanism is activation of coagulation. The role of nicotine in enhancing coagulability has not been resolved. METHODS: We compared in a crossover study the effects of cigarette smoking, transdermal nicotine and placebo transdermal nicotine, each for 5 days, in 12 healthy smokers. RESULTS: Cigarette smoking increased the urinary excretion of 11-dehydro-thromboxane B2 (reflecting thromboxane A2 generation) and increased plasma concentration of the platelet alpha-granule constituents, platelet factor 4 and beta-thromboglobulin, compared with placebo treatment, indicating in vivo platelet activation. Cigarette smoking was also associated with higher levels of fibrinogen in plasma. Transdermal nicotine produced plasma levels of nicotine in the same range as those during smoking but had no effect on thromboxane A2 metabolite excretion, platelet alpha-granule release or plasma fibrinogen, compared with placebo. Excretion of 2,3-dinor-6-keto-PGF1 alpha (reflecting prostacyclin generation) was not significantly influenced by any treatment. These results suggest that nicotine as such is not responsible for the platelet activation or elevation of plasma fibrinogen seen in smokers. However, we cannot exclude the possibility that intermittent bolus-like dosing of nicotine from cigarettes could have different effects from those produced by continually released transdermal nicotine. Other findings were that cigarette smoking and transdermal nicotine treatment were both associated with a higher white blood cell count compared with the placebo patch condition, suggesting a direct effect of nicotine to increase circulating white cells. Factor VII coagulant activity (VIIc) was significantly lower during cigarette smoking, than during either nicotine or placebo patch conditions. CONCLUSIONS: Transdermal nicotine has less effect on platelet activation and catecholamine release than does cigarette smoking, and its use in smoking cessation treatment of patients with coronary heart disease is likely to be safer than cigarette smoking.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Non-invasive ultrasound localization of impalpable breast lesions.

Thirty patients presenting through the Breast Screening Programme with impalpable breast abnormalities clearly visible on ultrasound, underwent non-invasive ultrasound localization. The patient was scanned so that the ultrasound abnormality lay below the probe and the skin at this site marked with a skin marker. In all cases the abnormality was easily identified and removed at surgery. All the surgical biopsies contained either a carcinoma (17 cases) or fibroadenoma (13 cases). This non-invasive technique is a simple and accurate method for localizing small ultrasonically visible breast abnormalities.

Adenoma↗
PubMed1993

Sensitisation of cariogenic bacteria to killing by light from a helium-neon laser.

Suspensions of the cariogenic bacteria Streptococcus mutans, S. sobrinus, Lactobacillus casei and Actinomyces viscosus were exposed to light from a 7.3-mW helium-neon laser in the presence of toluidine blue O. A substantial killing rate (c. 10(6) cfu) of all four species was achieved with a dye concentration of 50 micrograms/ml and a light energy dose of 33.6 J/cm2. This was achieved in 60 s, an exposure time that is clinically acceptable. Exposure to laser light in the absence of the dye did not significantly affect the viability of any of the organisms. This approach may be useful in dentistry to sterilise a carious lesion prior to its repair.

Actinomyces viscosus↗
PubMed1993

Prevalence of Treponema denticola and Porphyromonas gingivalis in plaque from periodontally-healthy and periodontally-diseased sites.

Intracrevicular plaque from periodontally-healthy individuals who had refrained from oral hygiene measures for 24 h prior to sampling, and subgingival plaque from diseased sites of patients with chronic periodontitis were screened by ELISA for the presence of Porphyromonas gingivalis and Treponema denticola. The samples were also subjected to the PerioScan test to detect the presence of enzymes capable of degrading N-benzoyl-DL-arginine-2-naphthylamide (BANA). Of the 141 samples from periodontally-healthy sites, 73% contained T. denticola antigens and 78% P. gingivalis antigens, compared to 43% and 59%, respectively, in plaque samples from the 159 diseased sites. A positive reaction in the PerioScan test was obtained in 89% of plaque samples from diseased sites and in 60% of those from healthy sites. The correlation between the results of the two assays was poor in the case of intracrevicular plaque from healthy sites. However, with plaque samples from diseased sites, the results of the PerioScan test showed very strong correlation with those obtained with the ELISA, suggesting that the former may be a useful, rapid means of indicating the presence of T. denticola and P. gingivalis in such plaque samples.

Adolescent↗
PubMed1993

Sensitization of periodontopathogenic bacteria to killing by light from a low-power laser.

Cultures of Porphyromonas gingivalis, Fusobacterium nucleatum and Actinobacillus actinomycetemcomitans were treated with a range of photosensitizers and then exposed to light from a 7.3 mW helium/neon laser for up to 80 s. Toluidine blue O (25 micrograms/ml) and methylene blue (25 micrograms/ml) were effective lethal photosensitizers of all 3 target organisms, enabling substantial light dose-related reductions in viable counts. Dihaematoporphyrin ester and aluminium disulphonated phthalocyanine were lethal photosensitizers only of P. gingivalis. In the absence of a photosensitizer, exposure to laser light had no significant effect on the viability of the cultures. If such low doses of light (22 J/cm2) are effective at killing bacteria in vivo, the technique may be useful as a means of eliminating periodontopathogenic bacteria from diseased sites.

Aggregatibacter actinomycetemcomitans↗
PubMed1993

Psychological factors and their relationship to diabetes control.

Thirty-nine Type 1 diabetic patients were asked to complete an Eysenck Personality Questionnaire (EPQ). A significant relationship was found between neuroticism scores and glycosylated haemoglobin concentrations (r = 0.43, p < 0.01) and also fructosamine (r = 0.45, p < 0.01). Patients with glycosylated haemoglobin concentrations greater than or equal to 10 (n = 13) had significantly higher neuroticism scores than patients with glycosylated haemoglobin results less than or equal to 8 (n = 11) (p < 0.01).

Adolescent↗
PubMed1993

Biological activities of surface-associated material from Porphyromonas gingivalis.

Surface-associated material (SAM) from Porphyromonas gingivalis was tested for in vitro biological activities that may be relevant to the pathogenesis of chronic periodontitis. SAM was found to stimulate bone resorption at a concentration of 1.0 microgram/ml and this was inhibited by indomethacin, interleukin-1 receptor antagonist protein and anti-tumour necrosis factor antibody. At a concentration of 10 ng/ml, the SAM inhibited DNA and collagen synthesis in osteoblasts and murine calvaria and DNA synthesis in fibroblasts, monocytes and epidermal cells. Therefore, easily solubilised surface components from P. gingivalis could play a role in the pathogenesis of chronic periodontitis if these activities operate in vivo.

Animals↗
PubMed1993

Sensitisation of Candida albicans to killing by low-power laser light.

The purpose of this study was to determine whether Candida albicans, and other Candida spp. responsible for HIV-associated candidosis, could be sensitised to killing by low-power laser light. Suspensions of C. albicans were treated with a number of potential photosensitisers, exposed to laser light from a Helium/Neon (HeNe) or Gallium aluminium arsenide (GaAs) laser for 120 s and survivors enumerated. Toluidine blue O (TBO), thionin and crystal violet were able to sensitise the yeast to killing by light from the HeNe laser (energy dose = 876 mJ at a density of 66.36 J/cm2), the kills achieved being 6.8 x 10(6) cfu/ml, 3.1 x 10(6) cfu/ml and 1.3 x 10(6) cfu/ml respectively. TBO was also able to sensitise several other Candida spp. to killing by HeNe laser light. Dihaematoporphyrin ester was not an effective photosensitiser under the conditions employed. Methylene blue, but not aluminium disulphonated phthalocyanine, was able to sensitise C. albicans to killing by light from the GaAs laser (energy dose 1.32 J at a density of 2.04 J/cm2). The viability of the yeast was not affected by exposure to laser light in the absence of the photosensitisers. As killing of dye-sensitised C. albicans, and other Candida spp., could be achieved by exposure to low-power laser light for short periods of time, this approach merits further investigation as a potential therapeutic modality for HIV-associated candidosis.

Aluminum↗
PubMed1993

Higher-titer antisera from patients with periodontal disease inhibit bacterial capsule-induced bone breakdown.

Solubilized surface-associated material (SAM) from a number of periodontopathogenic bacteria have been shown to be potent stimulators of bone resorption in vitro in the murine calvarial bone culture assay. Antibodies to the constituents of SAM are also found in patients with periodontal diseases. Serum from patients with severe generalized periodontitis (SGP) containing high titers of antibodies to the SAM of Porphyromonas gingivalis completely inhibited the bone resorption induced by SAM from this organism. In contrast, serum from patients with low titers of antibodies to SAM from P. gingivalis failed to inhibit bone resorption. High-titer sera (containing antibodies to SAM from Actinobacillus actinomycetemcomitans) from patients with localized juvenile periodontitis (LJP) were added to calvarial cultures stimulated with SAM from A. actinomycetemcomitans. Of 6 high-titer sera tested, only 4 inhibited bone breakdown, the other 2 sera having no effect on resorption. Low-titer sera were also ineffective at blocking bone resorption. This suggests that the antibody response to SAM may have a protective effect in patients with periodontal disease.

Aggregatibacter actinomycetemcomitans↗
PubMed1993

Lethal photosensitization of bacteria in subgingival plaque from patients with chronic periodontitis.

Subgingival plaque samples from patients with chronic periodontitis were exposed to light from a 7.3 mW Helium/Neon laser for 30 s in the presence and absence of 50 micrograms/ml toluidine blue O as a photosensitizer. Viable counts of various groups and species of bacteria were carried out before and after irradiation. The median numbers of viable bacteria initially present in the 30-microliters aliquots irradiated were 1.13 x 10(5) cfu (aerobes), 4.08 x 10(5) cfu (anaerobes), 4.92 x 10(3) cfu (black-pigmented anaerobes), 4.75 x 10(2) cfu (Porphyromonas gingivalis), 6.15 x 10(3) cfu (Fusobacterium nucleatum) and 1.7 x 10(4) cfu (streptococci). The dye/laser combination achieved significant reductions in the viability of these organisms, the median reductions in the viable counts being 91.1% for aerobes, 96.6% for anaerobes, 100% for black-pigmented anaerobes, P. gingivalis and F. nucleatum and 94.2% for streptococci. Overall, the viability of bacteria in the 20 plaque samples was not significantly decreased by the dye alone. However, in a small minority of samples there were indications of light-independent, dye-induced toxicity. Low-power lasers, in conjunction with appropriate photosensitizers, may be a useful adjunct to mechanical debridement in the treatment of inflammatory periodontal diseases if a similar effectiveness against subgingival plaque bacteria can be achieved in vivo.

Adult↗
PubMed1993

Effect of phenotypic plasticity on epiphytic survival and colonization by Pseudomonas syringae.

The bacterial epiphyte Pseudomonas syringae MF714R was cultured on agar or in broth or collected from colonized leaves; it was then inoculated onto greenhouse-grown bean plants incubated in a growth chamber at low relative humidity or in the field or onto field-grown bean plants. Cells cultured in liquid medium survived the least well after inoculation of leaf surfaces under all conditions. Cells cultured in solid medium exhibited the highest percent survival and desiccation tolerance in the growth chamber but generally survived less well in the field than did cells harvested from plants. Cells harvested from plants and inoculated onto plants in the field usually exhibited the highest percent survival, started to increase in population earlier, and reached a higher number than did cells cultured in vitro. Differences in field survival were apparently not attributable to differential UV tolerance. The observed effects of phenotypic plasticity on epiphytic survival and colonization should be considered in risk assessment studies, in studies of bacterial epidemiology, and in the use of microbial antagonists for biological pest control.

Bacteriological Techniques↗
PubMed1993

Release of recombinant microorganisms.

This review addresses current environmental applications of naturally occurring, nonrecombinant microorganisms and potential future genetic modifications of such organisms, as well as releases of recombinant microorganisms that have occurred to date. Awareness of the current uses of nonrecombinant microorganisms provides insight into the diversity of habitats in which recombinant microorganisms may be released in the future, while an examination of potential and realized genetic modifications provides insight into the variety of applications for which recombinant microorganisms may be used. Analysis of the behavior, persistence, and dispersal of nonrecombinant strains further provides valuable information required for the assessment of the risk involved in release of recombinant derivatives of those strains. Approximately 27 distinct releases of recombinant microorganisms have occurred to date. This review assesses what has been learned from such releases regarding persistence, dispersal, and potential deleterious environmental effects.

Bacteria↗
PubMed1993

DSM-III and the transformation of American psychiatry: a history.

The author traces the history of the development of DSM-III within the larger context--intellectual, economic, scientific, and ideological--of the development of American psychiatry since World War II. Data were obtained through a literature review, investigation of archival material from the DSM-III task force and APA, and interviews with key participants. This research indicates that from the end of World War II until the mid-1970s, a broadly conceived biopsychosocial model, informed by psychoanalysis, sociological thinking, and biological knowledge, was the organizing model for American psychiatry. However, the biopsychosocial model did not clearly demarcate the mentally well from the mentally ill, and this failure led to a crisis in the legitimacy of psychiatry by the 1970s. The publication of DSM-III in 1980 represented an answer to this crisis, as the essential focus of psychiatric knowledge shifted from the clinically-based biopsychosocial model to a research-based medical model. The author concludes that while DSM-III, and the return to descriptive psychiatry which it inaugurated, has had positive consequences for the profession, at the same time it represents a significant narrowing of psychiatry's clinical gaze.

History, 20th Century↗
PubMed1993

Osmotic production of sterile oral rehydration solutions--an economic, low-technology method.

A sterile oral rehydration solution can be produced by immersing in water a semi-permeable cellulose tube containing glucose and salts. Osmotically-driven ultrafiltration excludes all microbes and particulate matter even when the immersion water contains 45 x 10(6) cfu/ml of Pseudomonas aeruginosa, 25 x 10(7) cfu/ml of Staphylococcus aureus or 20 x 10(7) cfu/ml of Escherichia coli. Solutions of consistent composition can be obtained by having a standard amount of glucose-electrolytes in a cellulose tube of appropriate dimensions and immersing this in a fixed volume of water for a minimum period of time. The method is simple, inexpensive, low-technology and requires no external source of power. It has potential for producing sterile solutions for injections and intravenous use in situations with very limited and simple resources, in emergencies and during natural disasters. Further studies are now needed to determine whether the method can be adapted to provide the large quantities of oral rehydration fluid needed in field conditions.

Humans↗
PubMed1993

Synaptic transmission between pairs of retinal amacrine cells in culture.

We have examined synaptic transmission between isolated pairs of chick GABAergic amacrine cells, maintained in sparse culture and identified by their binding of an amacrine cell-selective antibody. Using the perforated-patch method to whole-cell clamp both cells of a pair, postsynaptic currents were examined for step depolarizations of the "presynaptic" cell. Synaptic transmission, frequently reciprocal, was calcium dependent and reversibly blocked by bicuculline. Post-synaptic currents, excluding those due to ohmic electrical coupling, were elicited only for presynaptic voltage steps positive to about -40 mV and were always very noisy, suggesting that they were summed from relatively small numbers of quanta. Postsynaptic currents continued well after the termination of the 100 msec presynaptic voltage step when the step was to -10 mV, or positive to this value. This result is interpreted to imply that presynaptic calcium concentration remains elevated after the membrane is returned to its holding potential. When presynaptic voltages were kept low or else presynaptic voltage was uncontrolled, spontaneous quantal events mediated by GABAA receptors could often be seen. Quanta rose quickly (less than 4 msec) and decayed with a mean time constant of 19.3 msec. The amplitude distributions of quantal currents were positively skewed, sometimes showing rare quanta of exceptionally large amplitude. Peak conductance per quantum was about 300 pS, corresponding to the simultaneous opening of only 17 GABAA channels and corresponding to a net flux of only 32 x 10(3) Cl- ions per millivolt of driving force. Estimates of the maximum sustained release rate at individual release sites suggest an upper bound of between 19 and 42 quanta per second.

Animals↗