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Biomedical subjects

D A Ferguson

Publications and source records attributed to D A Ferguson.

At least 37 records · Page 2Linked to original sources
PubMed1993

Clinical aspects of malignant mesothelioma in Australia.

Australia is currently experiencing an epidemic of malignant mesothelioma. The clinical aspects of malignant mesothelioma were investigated in 295 Australian patients as part of a national study of the disease. Most patients were male (91%), with the mean age at diagnosis being 64 years. The predominant cell type was epithelial (38%) and the majority of primary tumours arose from the pleura (94%). Mean survival was poor (17.6 months from first symptom; 11.8 months from diagnosis). Patients with a pleural primary tumour were more likely to present with dyspnoea, chest pain and cough; to have a pleural effusion diagnosed radiologically; and to have metastatic spread. Patients with a peritoneal primary tumour were more likely to present with weight loss, loss of appetite, abdominal pain and ascites; to have radiologic evidence of asbestos exposure; and to have spread along a needle track created during a diagnostic tap. A minority of patients had past thoracic conditions, or radiologic findings, specifically related to previous asbestos exposure. About one fifth of patients had no known asbestos exposure. Forty-one per cent of subjects received some form of chemotherapy, radiotherapy and/or surgery, but no formal disease staging had been documented for any patient. Proper controlled trials of secondary and tertiary treatments in malignant mesothelioma are now needed.

Aged↗
PubMed1993

Isolation of Helicobacter pylori from saliva.

Helicobacter pylori was grown in low numbers from the saliva of one of nine patients who were positive for gastric H. pylori. The saliva-derived isolate from this patient was identical to the antral biopsy-derived isolate from the same patient and differed from isolates cultured from the antral biopsies of all other patients by soluble-protein electrophoresis, restriction endonuclease DNA analysis, and Southern blot hybridization. This is the first observation, to our knowledge, of the recovery of viable H. pylori from saliva.

Fatty Acids↗
PubMed1993

A highly specific and sensitive DNA probe derived from chromosomal DNA of Helicobacter pylori is useful for typing H. pylori isolates.

HindIII-digested DNA fragments derived from an EcoRI-digested 6.5-kb fragment of chromosomal DNA prepared from Helicobacter pylori ATCC 43629 (type strain) were cloned into the pUC19 vector. A 0.86-kb insert was identified as a potential chromosomal DNA probe. The specificity of the probe was evaluated by testing 166 non-H. pylori bacterial strains representing 38 genera and 91 species which included aerobic, anaerobic, and microaerophilic flora of the upper and lower gastrointestinal tracts. None of the 166 non-H. pylori strains hybridized with this probe (100% specificity), and the sensitivity of this probe was also 100% when H. pylori isolates from 72 patients with gastritis and with the homologous ATCC type strain were tested by dot blot hybridization. The capability of this probe for differentiating between strains of H. pylori was evaluated by Southern blot hybridization of HaeIII-digested chromosomal DNA from 68 clinical isolates and the homologous ATCC type strain of H. pylori. Fifty-one unique hybridization patterns were seen among the 69 strains tested, demonstrating considerable genotypic variation among H. pylori clinical isolates. We propose that this probe would be of significant value for conducting epidemiologic studies.

Bacterial Typing Techniques↗
PubMed1992

Bacteroides and Staphylococcus glycocalyx: chemical analysis, and the effects on chemiluminescence and chemotaxis of human polymorphonuclear leucocytes.

Glycocalyx (or slime), which is an important virulence factor of many pathogenic bacteria, was isolated from Bacteroides fragilis, Bacteroides thetaiotaomicron and Staphylococcus epidermidis. Organisms were grown for 24 h in a chemically defined, dialysable liquid medium. Bacteria were centrifuged and the supernatant was concentrated and dialysed against distilled water. Total carbohydrate and protein were estimated using standard methods. Thin layer and gas-liquid chromatography of trifluoro acetic acid hydrolysed and non-hydrolysed samples provided evidence for the presence of polysaccharide, the absence of nucleic acids and lipopolysaccharide and for the identification of the individual sugar residues. Glucose, mannose and galactose (B. fragilis), glucose (B. thetaiotaomicron), and glucose and heptose (S. epidermidis) were the sugar residues detected. Uronic acid and hexosamine were detected in all species. Glycocalyx preparations (1 mg/ml) from Bacteroides and Staphylococcus significantly inhibited the chemiluminescence and chemotactic responses of viable human polymorphonuclear leucocytes (PMNL), but were not toxic for PMNL.

Bacteroides↗
PubMed1991

Lung asbestos fiber content and mesothelioma cell type, site, and survival.

All ascertainable cases of malignant mesothelioma in Australia were notified to a national surveillance program in the period January 1, 1980 to December 31, 1985. There were 854 cases obtained and 823 confirmed on clinical (77) or histologic (746) ground. Tumor site was known in 759 cases (685 pleural and 74 peritoneal). Lung fiber content analyses by light microscopy and analytic transmission electron microscopy with energy-dispersive x-ray analysis were done on 226 cases in which postmortem material was available, using the method of Rogers. Cell type was determined by a five-member expert panel of pathologists appointed by the Royal College of Pathologists of Australasia. There was a statistically significant trend between lung fiber content (fibers/g dry lung) and cell type from epithelial (low fiber content) through mixed to sarcomatous (high fiber content). This trend was most apparent for total uncoated fibers (chi-square = 6.8, df = 1, P less than 0.01) and crocidolite (chi-square = 6.7, df = 1, P less than 0.01). Lung fiber content also was associated with tumor site; higher lung fiber content being associated with peritoneal tumors. This relationship was significant for all fiber content measures except chrysotile and was independent of the fiber content-cell type relationship (log-linear analysis). Survival from time of provisional diagnosis was significantly longer for epithelial (mean, 13 months; standard deviation [SD], 12.8) and mixed (mean, 10.2 months; SD, 8.7) types than sarcomatous cell types (mean, 5.8 months; SD, 6.5; P less than 0.0001, by analysis of variance on log10 survival time). Survival time was significantly greater for pleural tumors (mean, 11.4 months; SD, 13.4) than peritoneal tumors (mean, 8.6 months; SD, 12.5) (P less than 0.005, by Student's t test on log10 survival time).

Asbestos↗
PubMed1991

Relationship between lung asbestos fiber type and concentration and relative risk of mesothelioma. A case-control study.

Lung tissue from 221 definite and probable cases of malignant mesothelioma reported to the Australian Mesothelioma Surveillance Program from January 1980 through December 1985 and from an age-sex frequency matched control series of 359 postmortem cases were examined by light microscopic (LM) and analytical transmission electron microscopic (TEM) analysis and energy dispersive x-ray analysis (EDAX). Concentrations of total fibers (coated and uncoated) (LM), crocidolite, amosite, chrysotile, and unidentified amphibole (TEM) (fibers/g dry lung tissue) were measured. Fiber concentrations less than 10 microns in length and greater than or equal to 10 microns in length were separately quantified. By comparing cases (221) and controls (359 LM, 103 TEM), odds ratios for increasing fiber concentrations compared with less than 15,000 fibers/g (LM) and less than 200,000 fibers/g (TEM) (the respective detection limits) were calculated. Univariate analyses showed statistically significant dose-response relationships between odds ratio and fiber concentration for all fiber concentration measures. The relationship between log(odds ratio) and log(fiber concentration) was linear. Multiple logistic regression analysis showed that a model containing crocidolite greater than or equal to 10 microns, amosite less than 10 microns, and chrysotile less than 10 microns as explanatory variables best described the data. The odds ratios for a X10 increase in fiber concentration (fibers/micrograms) were as follows: crocidolite greater than or equal to 10 microns, 29.4 (95% confidence interval [CI], 3.6 to 241); chrysotile less than 10 microns, 15.7 (95% CI, 6.1 to 40); amosite less than 10 microns, 2.3 (95% CI, 1.0 to 5.3). An additive risk model gave similar results. In a subgroup of cases and controls with only chrysotile in the lungs, a significant trend in odds ratio with increasing fiber content was found.

Adult↗
PubMed1991

The incidence of malignant mesothelioma in Australia 1982-1988.

From 1980 to 1985, the Australian Mesothelioma Surveillance Program, and since 1986, the Australian Mesothelioma Register, have been collecting data on all cases of malignant mesothelioma that could be ascertained in Australia. Incidence rates were calculated on 854 Program and 696 Register cases (total 1271) diagnosed in Australia between January 1, 1982 and December 31, 1988. Australia has one of the highest national rates of mesothelioma in the world (15.8 cases per million of population aged 20 years and older), and the rate is rising. The rate is far higher in males (28.3) than females (3.3). The Western Australian rate (28.9) is the highest among the states, as may be expected because of the crocidolite mine at Wittenoom; however, the largest numbers of cases occur in the more populous and industrial New South Wales. The high incidence rate, its expected continuing increase, and absence of a history of exposure to asbestos in approximately 28% of cases, demand consideration of potential environmental factors other than asbestos in the causation of this tumor, as well as continued surveillance.

Adult↗
PubMed1990

A randomised controlled trial of counseling in a workplace setting for coronary heart disease risk factor modification: effects on blood pressure.

This paper reviews a prospective study of occupational factors in coronary heart disease risk incorporated in a randomised controlled trial of a worksite based occupational health nurse counseling program for reducing coronary heart disease risk factors. The aim of the trial was to evaluate the longterm effectiveness of the counseling program in persons with mildly elevated risk factor levels. Of the 2,489 Australian government employees with mildly elevated risk factor levels who entered the intervention trial, 1,937 (78%) attended a followup examination three years later. This paper reports on changes in systolic and diastolic blood pressure. Multiple linear regression models were used with three-year blood pressure reduction as the dependent variable, intervention status as the main determinant, and sex, age, initial risk level and initial blood pressure as covariates. Although systolic and diastolic blood pressure fell in both the intervention and control groups, intervention was significantly associated with systolic blood pressure change only.

Adult↗
PubMed1990

Chronic perceived work stress and blood pressure among Australian government employees.

Prospective data on 2634 Australian government employees over five years were examined for the effects of chronic perceived work stress on blood pressure change. The study sample (2100 men and 534 women) represented 57% of the original volunteers, or 75% of those eligible after exclusion criteria were met. Data on perceived stress were obtained by questionnaire, and a principal component analysis produced six components: qualitative demands, quantitative demands, job control, future control, work support, and outside stress. Multiple linear regression, which controlled for determinants of blood pressure, tested the main effects and specific two-way interaction effects of the chronicity scores of the six components and 30 items. Many items but only some components were associated with blood pressure change. Sex and age differences were observed. The observed interactions between job demands and control provided equivocal support for the Karasek job-strain model. The women responded to work-based support, but not necessarily as predicted.

Adult↗
PubMed1989

Evaluation of a worksite programme for the modification of cardiovascular risk factors.

This article reports on the long-term results of a randomized controlled trial of non-pharmacological intervention for mildly-elevated levels of cardiovascular risk factors. The intervention consisted of individual counselling by occupational health professionals. From a population of 4607 volunteers who were working for Australian government organizations, a sample of 2489 subjects met the eligibility criteria for the trial, and 1937 subjects were available for follow-up examination three years later. Changes in the levels of risk factors favoured the interventional group marginally and appeared to vary with the sex, age and occupation of the subjects. A significant effect of intervention was noted for systolic blood pressure levels; however, although this interventional effect was more pronounced in men of 40 years of age or over and in administrative workers, clinically it was small. The results suggest that individual counselling, as undertaken in this study, generally is not effective in the long-term modification of mildly-elevated cardiovascular risk factors.

Adult↗
PubMed1989

Trospectomycin enhances surface phagocytosis of Bacteroides and Staphylococcus by altering the bacterial glycocalyx.

The influence of trospectomycin on phagocytosis of Bacteriodes thetaiotaomicron, Bacteroides fragilis and Staphylococcus epidermidis was studied in the presence or absence of glycocalyx isolated from these microorganisms. Bacteria were grown with or without 0.25 or 0.5 of the minimal inhibitory concentration (MIC) of trospectomycin, a new chemically synthesized analog of spectinomycin. Surface phagocytosis by human polymorphonuclear leukocytes (PMNL) was determined using a modified fluorochrome assay. Subinhibitory concentrations of trospectomycin significantly enhanced surface phagocytosis of Bacteroides and Staphylococcus. When homologous or heterologous isolated glycocalyx was added to trospectomycin treated bacteria prior to incubation with PMNL, phagocytosis was reduced to levels observed in the untreated bacteria. Addition of glycocalyx to untreated strains produced no significant reduction of phagocytosis. The glycocalyx preparations were free of lipopolysaccharide and did not affect PMNL viability.

Anti-Bacterial Agents↗
PubMed1989

Enhancement of opsonophagocytosis of Bacteroides spp. by clindamycin in subinhibitory concentrations.

Radioactively labelled bacteria were incubated overnight in the presence or absence of one-half the MIC of clindamycin, then preopsonized with normal human serum or homologous rabbit antiserum and incubated with human polymorphonuclear leucocytes. Clindamycin in subinhibitory concentrations significantly enhanced the phagocytosis of all four Bacteroides strains. Complement-dependent as well as antibody-dependent phagocytosis was enhanced by clindamycin in one Bacteroides strain. In the other three strains, only antibody dependent phagocytosis was enhanced by clindamycin. Transmission electron microscopy confirmed phagocytosis of the bacteroides.

Antibodies, Bacterial↗
PubMed1989

The role of glycocalyx in surface phagocytosis of Bacteroides spp., in the presence and absence of clindamycin.

The influence of isolated glycocalyx from Bacteroides thetaiotaomicron and B. fragilis on surface phagocytosis of clindamycin-treated and -untreated homologous and heterologous species was studied. When homologous or heterologous isolated glycocalyx was added to clindamycin-treated B. thetaiotaomicron or B. fragilis before incubation with PMNL, phagocytosis was reduced to levels observed in the untreated control bacteria, but addition of glycocalyx to untreated control strains showed no reduction of phagocytosis. When isolated bacteroides-glycocalyx was added to Staphylococcus aureus or S. epidermidis, phagocytosis of both clindamycin-treated and -untreated bacteria was significantly reduced. The isolated glycocalyx preparations were analysed by thin layer and gas-liquid chromatography; these preparations were free of lipopolysaccharides. The isolated glycocalyx did not affect PMNL viability. Our findings suggest that the glycocalyx is an important virulence factor because it impairs phagocytosis of Bacteroides spp. by PMNL. Clindamycin may enhance opsonophagocytosis of bacteroides by altering the glycocalyx.

Bacteroides↗
PubMed1988

Rickets associated with vitamin D deficiency in young sheep.

An outbreak of rickets in sheep under a year old (hoggs) appeared clinically as stiffness and rotation of the carpal joints. Histological studies confirmed the diagnosis and biochemical analyses of blood demonstrated a primary vitamin D deficiency.

Animals↗
PubMed1988

The Bacteroides glycocalyx as visualized by differential interference contrast microscopy.

The glycocalyx of eight strains representing six species of Bacteroides was examined by differential interference contrast microscopy. Wet mounts in India ink were prepared from bacteria cultured in broth and on an agar medium; the wet mounts were observed by phase-contrast microscopy and differential interference contrast microscopy. With differential interference contrast microscopy, all bacteria demonstrated a glycocalyx, which included capsules surrounding single cells and microcolonies, strands of glycocalyx connecting cells and microcolonies, detached slime, and solid masses of glycocalyx in which innumerable bacteria were enmeshed. Bacteria showed comparable amounts of glycocalyx by visual observation with differential interference contrast microscopy whether grown on plates or in broth. Serial transfers of cultures did not diminish the amount of glycocalyx. Differential interference contrast microscopy proved to be a superior method to phase contrast for examining wet preparations of Bacteroides.

Bacteroides↗
PubMed1987

The Australian Mesothelioma Surveillance Program 1979-1985.

The Australian Mesothelioma Surveillance Program was planned in 1977 in order to improve diagnostic criteria, to monitor the incidence of the disease, to develop methods of counting lung fibres, and to explore occupational and other associations of mesothelioma. This paper presents a preliminary analysis of data that were collected between January 1, 1980 and December 31, 1985 on the pathological findings and the work and environmental history of 858 cases of mesothelioma. The annual incidence rate of mesothelioma in Australia was 15 per million population who were aged 20 years and over. This is more than the incidence rate of mesothelioma in any other country for which data are available. However, uncertainty over diagnostic criteria and the degree of ascertainment of cases places doubt on the validity of such comparisons. In 69% of cases, a history of work with or other exposure to asbestos was obtained. Due to the long interval between the first exposure to asbestos and the provisional diagnosis of a mesothelioma (up to 60 years), more than three-quarters of the 456 exposed cases first contacted asbestos in the years of its heavy use between 1930 and 1959. This article analyses cases by the industry and the occupation in which exposure to asbestos first occurred.

Adult↗