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Biomedical subjects

R S Roberts

Publications and source records attributed to R S Roberts.

At least 91 records · Page 5Linked to original sources
PubMed1985

Designs for the evaluation of the endotoxin assay as a diagnostic test.

The comprehensive evaluation of the usefulness of a new diagnostic test should include a hierarchy of assessments ranging from reliability and validity to impact on clinical decision making and outcome. This paper reviews some of the design methodology appropriate for evaluation of an endotoxin assay such as the Limulus Amebocyte Lysate test. Primary focus is on the design and analysis of studies aimed at establishing diagnostic validity. However, suggestions are made for the design of clinical studies of management change and to determine the impact on patient outcome. Results from such studies must be combined into a cost-utility calculation eventually to determine societal benefit.

Bacterial Infections↗
PubMed1984

Is cimetidine being prescribed indiscriminately? An analytic survey of patients who present with symptoms of peptic ulcer disease.

An analytic survey was done to determine the influence of previously documented peptic ulcer disease (PUD) on the frequency of prescribing cimetidine to patients who present at a family medicine centre with symptoms of PUD. It was found that of 293 patients who presented with such symptoms over 1 year cimetidine was prescribed to 57 (19%). From the 236 patients who did not receive cimetidine 57 patients were selected at random for comparison. Information on these two groups of patients was obtained by chart review. The patients who received cimetidine were found to be significantly more likely (p less than 0.001) to have previously documented PUD than those who did not receive cimetidine. In patients in whom subsequent confirmation of PUD was not obtained, either because the results of investigations were negative or because the investigations were not ordered, cimetidine was prescribed to 63% of those who had previously documented PUD, compared with only 6% of those who did not. Of the patients who were investigated 73% of those with previously documented PUD had positive results, compared with 8% of those without previously documented PUD. The positive results were obtained by endoscopic examination in 88% of the patients with previously documented PUD, whereas upper gastrointestinal tract roentgenography was the definitive test in 73% of the patients without previously documented PUD. These findings suggest that previously documented PUD influences both the frequency of prescribing cimetidine and the investigations that are carried out.

Adult↗
PubMed1984

Prediction of late asthmatic responses to inhaled allergen.

Relationships between cutaneous and bronchial responses to allergen were examined in nineteen atopic asthmatics. Allergen inhalation tests elicited an isolated early asthmatic response (EAR) in ten subjects and a dual asthmatic response (DAR) in nine subjects. Ragweed IgE RAST, performed with the sera of those patients tested with ragweed antigen, yielded higher values in all but one patient who experienced DAR than any of the patients with EAR. In one patient with annual symptoms in the ragweed season, positive skin tests with ragweed antigen and DAR to inhaled ragweed extracts, the IgE RAST was entirely negative and the serum IgE concentration was low. Dilutions of the allergen used in each individual for inhalation were also used in skin-prick tests. Early cutaneous allergic response (ECAR) mean wheal diameters were obtained at 10 min and late cutaneous allergic response (LCAR) mean diameters at 6-8 hr. Early asthmatic response (EAR) subjects differed modestly from DAR subjects in the relationships between ECAR and LCAR; in the EAR group, a significantly larger wheal diameter (P less than 0.01) was required before an LCAR ensued, however there was some overlap. Once LCAR developed, there was no difference between EAR and DAR groups in the magnitude of the LCAR. There was a trend (not significant) towards a requirement for a higher antigen concentration in the EAR group to elicit an LCAR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Bronchial responsiveness to methacholine in chronic bronchitis: relationship to airflow obstruction and cold air responsiveness.

The response to inhaled methacholine is increased in patients with chronic airflow obstruction, but it is not known whether this is due to true hyperresponsiveness or is a result of the airflow obstruction. In asthmatics the response to methacholine correlates with the bronchoconstriction produced by hyperventilation of cold dry air. We studied 27 patients with a history of smoking and chronic bronchitis with a range of severity of airflow obstruction. Bronchial responses to methacholine (expressed as the provocation concentration causing a fall in FEV1 of 20%-PC20) and isocapnic hyperventilation of cold dry air were measured. In 19 patients the PC20 was less than 8 mg/ml (that is, in the asthmatic range) but only three developed bronchoconstriction in response to hyperventilation. There was a linear correlation between the log PC20 and the FEV1 (r = 0.86, p less than 0.001). The results suggest that in patients with chronic airflow obstruction the response to methacholine is determined by the degree of airflow obstruction, and cannot be used in the diagnosis of asthma in the absence of additional information.

Adult↗
PubMed1984

Lung epithelial permeability: relation to nonspecific airway responsiveness.

Lung epithelial permeability was measured in five normal, five asthmatic, and five smoking subjects by quantifying removal from the lung and accumulation in the blood of an inhaled radiolabeled low-molecular-weight substance, technetium-99m-labeled diethyleneaminepentaacetate (99mTc-DTPA). Measurements on 2 control days were highly reproducible. Nonspecific bronchial responsiveness to histamine was determined in all subjects on a 3rd day, and the results were expressed as the provocation concentration producing a fall in forced expiratory volume in 1 s of 20% (PC20 histamine). Lung epithelial permeability was similar for the normal and asthmatic subjects. However, smokers had greatly increased permeability when compared with the other two groups. The responsiveness to histamine was increased in the asthmatics but within the normal range for normal subjects and smokers. No relationship was established between increased epithelial permeability and increased responsiveness to histamine. Results indicate that increased permeability of the epithelial lining of the bronchi is not a dominant factor in the increased nonspecific responsiveness to histamine observed in asthma.

Adult↗
PubMed1984

The effect of atropine on allergen-induced increases in bronchial responsiveness to histamine.

We examined the role of cholinergic mechanisms in causing the increase in histamine bronchial responsiveness that follows allergen exposure. Five stable adult atopic asthmatics received inhalation tests with histamine on 2 days after both placebo and a dose of atropine sulphate (18 mg nebulized during tidal breathing), which reduced saliva output. On a third day, an allergen inhalation test was carried out to stimulate a dual asthmatic response. When the FEV1 had returned to within 10% of baseline, the histamine test was repeated after placebo and atropine. Before allergen inhalation, atropine marginally increased the FEV1 (p = 0.12) and reduced bronchial responsiveness to histamine (p = 0.003). When allergen challenge had induced an increase in histamine responsiveness (p = 0.001), atropine again marginally increased FEV1 (p = 0.063) and reduced the responsiveness (p = 0.004) but did not return the responsiveness to the preallergen level (p = 0.023). There was no evidence that the magnitude of the atropine blockade of histamine responsiveness was different before and after allergen (p = 0.92). We conclude that cholinergic mechanisms are not likely to explain the increase in bronchial responsiveness that follows allergen-induced inflammation.

Adult↗
PubMed1984

Cancer mortality associated with the high-temperature oxidation of nickel subsulfide.

An historical prospective mortality study of INCO's Ontario work-force has been conducted. A cohort of approximately 54 000 men, employed in all aspects of the extraction and refining of copper and nickel from the Sudbury ore deposit, have been followed for mortality between 1950 and 1976. A total of 5 283 deaths were identified by computerized record-linkage to the Canadian Mortality Data Base of death certificates. The analysis focuses on mortality from cancer of the nasal sinuses, larynx, lung, and kidney. Little evidence was found for increased mortality from laryngeal or kidney cancer, but lung and nasal cancer deaths were clearly elevated in men exposed to the two Sudbury area sinter plants and at Port Colborne in the leaching, calcining, and sintering department. The standardized mortality ratio (SMR) for lung cancer increases linearly with increasing duration of exposure and there is no evidence of a threshold. The nasal cancer mortality rate also rises linearly with duration of exposure. While lung cancer has a greater excess in the Sudbury sinter plant than at Port Colborne, the reverse is true for mortality from nasal cancer, which is ten times more frequent at Port Colborne than at Sudbury.

Adult↗
PubMed1984

A mortality study of 11,500 nickel workers.

A historical prospective mortality study was conducted at a nickel company with mines, mills, and a smelter in Ontario, Canada. All men were included in the study who worked for a total of at least 6 months and were employed at some time between 1950 and 1976. Mortality was ascertained and observed number of deaths (O) were compared with expected number of deaths (E), on the basis of the person-years method with the use of rates for Ontario males. There were 804 O compared to 743 E (P less than .001). However, the excess was more than accounted for by the increase in accidental and violent deaths (O = 242; E = 150). Deaths from circulatory diseases and all cancers were roughly equal to E. Laryngeal cancer mortality was significantly increased due to an excess in miners (O = 4; E = 1.00). Lung cancer mortality was somewhat increased (O = 46; E = 37.5); no nasal cancers were observed. Three deaths were due to pneumoconiosis. Sinter plant workers showed a significant increase of cancer deaths (O = 13; E = 6.7; P = .015).

Accidents↗
PubMed1984

Use of a bivalved polypropylene orthosis in the postoperative management of idiopathic scoliosis.

Forty-four consecutive patients with idiopathic scoliosis treated by posterior spinal fusion and Harrington rod instrumentation were immobilized after surgery with bivalved polypropylene orthoses. Immediate ambulation was allowed, and the patients wore the orthoses for a mean of 5.9 months. Brace removal was permitted with the patient recumbent for sponge bathing. These patients were followed up for a mean of 2.1 years (range, 1.0-4.3 years). The average final correction for all curves was 45%. The average loss of correction was 2.4 degrees (5.3%). Combined distraction and compression instrumentation was found to improve final correction in all curves by 3 degrees (6.2%) as compared with distraction instrumentation alone. There were no pseudarthroses and no rod breakage. Patients enjoyed the benefits of improved personal hygiene, pleasing cosmetic appearance, and increased life-style flexibility, especially swimming, which was not possible with the conventional Risser plaster cast. Use of the polypropylene orthosis offers significant advantages as compared with previous methods of postoperative management: it not only provides consistently good results but is enthusiastically accepted by patients as well.

Adolescent↗
PubMed1983

When is a patient's use of primary care services unwarranted? Some answers from physicians.

To explore physicians' perceptions of what constitutes unwarranted use of their services, examples of patient-initiated encounters considered unwarranted were contributed by physicians and categorized as requests for unnecessary services, inappropriately timed encounters or inconsiderate requests. A random sample of family and general practitioners in Ontario was surveyed with a questionnaire derived from these examples. Although there was no unanimity, examples of missed appointments, requests for further, unnecessary investigations, consultations or admissions to hospital, duplication of services, visits prompted by a desire to obtain free samples of over-the-counter drugs, some out-of-hours calls, and visits of healthy workers to obtain notes regarding fitness for work were seen as unwarranted by 70% or more of the respondents.

Canada↗
PubMed1983

Asthma and increases in nonallergic bronchial responsiveness from seasonal pollen exposure.

Serial measurements of symptoms, peak flow rates, methacholine bronchial responsiveness, and ragweed-specific IgE antibodies were made before and during the ragweed pollen season in 13 sensitized subjects. Allergen inhalation tests were carried out with aerosols of pollen extract out of season in nine subjects; isolated early asthmatic responses were provoked in four, and dual responses (early followed by late) were provoked in five. During the pollen season all subjects developed hay fever and eight had symptoms of asthma. There was a real increase in methacholine responsiveness during the ragweed season. This increase appeared before or after the occurrence of asthma symptoms and changes in flow rates and was greater in subjects with symptoms in the pollen season, dual responses after allergen inhalation tests, and higher levels of ragweed-specific IgE antibodies. The results confirm the occurrence of seasonal asthma and increases in nonallergic (nonspecific) bronchial responsiveness to methacholine from seasonal pollen exposure. They suggest that the occurrence of symptoms is closely linked to the allergic inflammatory reaction and the induction of increased nonallergic responsiveness.

Adolescent↗
PubMed1983

The protective effect of inhaled chlorpheniramine and atropine on bronchoconstriction stimulated by airway cooling.

We examined the role of histamine release and reflex bronchoconstriction in the bronchoconstriction stimulated by airway cooling. In 8 asthmatic subjects, dose-response curves were determined to isocapnic hyperventilation of cold air 30 min after inhalation of chlorpheniramine maleate (18 mg nebulized during tidal breathing), 2 doses of atropine sulphate (3 mg and 18 mg nebulized), or placebo. Treatments were given on separate days, in random order and under double-blind conditions. The bronchial antihistamine and anticholinergic actions of chlorpheniramine were determined by the effect on histamine and methacholine dose-response curves on another 4 days. Chlorpheniramine was selective as an antagonist against histamine; it increased the mean provocation concentration of histamine to reduce the FEV1 by 20% (PC20) 14.2-fold but increased the mean PC20 methacholine only 1.85-fold. Atropine in the 3-mg dose, previously shown to increase the PC20 methacholine at least 100-fold, had no effect on heart rate or saliva output in contrast to 18 mg, which significantly reduced saliva output and increased heart rate. Chlorpheniramine caused no bronchodilation and a small 1.28-fold increase in the amount of respiratory heat exchange needed to reduce the FEV1 by 10% (PD10RHE). Atropine caused maximal bronchodilation after 3 mg and a dose-dependent increase in PD10RHE (1.16-fold increase after 3 mg and 1.32-fold increase after 18 mg atropine). The effect of chlorpheniramine and atropine 18 mg on PD10RHE was not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Some physical signs in patients with chronic airflow obstruction.

Forty subjects with chronic airflow obstruction were examined independently by 2 observers, and their assessment of several physical signs was recorded. Spirometry and lung volumes were measured. Most of the signs studied correlated closely with the degree of airflow obstruction as assessed by the forced expiratory volume in one second. Certain signs also correlated closely with the degree of hyperinflation, the duration of symptoms, or the age of the subject. The agreement between observes in this study was good. Although all the signs are related in one way or another to the severity of airflow obstruction, some are due to large variations in intrathoracic pressure, some to hyperinflation and some, possibly, to changes in the shape of the chest and the action of the respiratory muscles. Hence, we suggest that these signs should not be regarded as inferior to tests of pulmonary function; physical examination and spirometry should be complementary.

Adult↗
PubMed1981

High-altitude retinopathy.

Thirty-nine healthy subjects were examined before and after a stay at 5,360 m by ophthalmoscopy and by retinal photography. Twenty of them were also tested for visual acuity, scotomata, and capillary leakage. Vascular engorgement and tortuosity and disc hyperemia were seen in all subjects at altitude and are a "normal" response to hypoxia. Twenty-two (56%) of the subjects had retinal hemorrhages and one showed "cotton-wool spots". These changes are abnormal reactions and are considered high-altitude retinopathy. After maximal exertion on a cycle ergometer, fresh hemorrhages were observed in seven of 34 subjects. The incidence of hemorrhage associated with exercise was significantly greater than predicted. Fluorescein leakage was noted after exercise in eight of 20 persons tested and was associated with exercise-induced hemorrhages. Two persons developed premacular hemorrhages.

Adult↗
PubMed1981

Complications of labor and delivery following uncomplicated pregnancy.

Renewed interest in less costly, less technologically oriented obstetrical care requires the accurate selection of women who may safely benefit from such alternatives. The distribution of complications of labor and delivery, among healthy women who had had uncomplicated pregnancies, was investigated by studying data from more than 240,000 birth certificates filed with the New York City Department of Health during the period 1971-1974. Complications of labor or delivery were reported for 21.0 per cent of births following apparently uncomplicated antepartum courses. Significantly higher rates of recorded complications were found for women who had initiated prenatal care earlier in pregnancy, for private patients as opposed to general service patients, for white patients compared to nonwhite patients, for married women than for unmarried women, and for better educated patients as opposed to those with less schooling. Labor and delivery complication rates were also noted to rise with maternal age. The positive association between earlier prenatal care and higher complication rates was found within all service, racial, marital, educational and age categories, and appeared to be independent of these variables. Factors which may contribute to these unexpected patterns, and further research to clarify them, are discussed.

Adolescent↗
PubMed1981

Standardization of inhalation provocation tests: two techniques of aerosol generation and inhalation compared.

Comparison of methods of aerosol generation and inhalation is required to improve standardization of inhalation provocation tests. We compared two widely used methods in 10 asthmatics, by measuring the dose and distribution of radiolabeled aerosol deposited in the throat and lung, and the provocation concentration of inhaled histamine required to reduce the FEV1 by 20% (PC20). In one method, aerosol was generated by a DeVilbiss 646 nebulizer attached to a dosimeter, and was inhaled by 5 inspiratory capacity breaths. The measurements with each method were repeated once to determine the reproducibility of results. Both methods deposited the same dose in the lung, but the distribution of the dose was different; the dosimeter method deposited more aerosol in the throat and central airways. The PC20 obtained with each method was the same. The reproducibility of all measurements in the same subject was similar. The lung dose deposited by each method in different subjects varied to the same degree. The results indicated that the bronchial response to inhaled histamine can be measured as reliably using a nebulizer and tidal breathing as by a more complex dose-metering device. They also suggested that, when the methods are regulated as described, the PC20 will have the same clinical significance.

Adolescent↗
PubMed1981

Multiple choice questions for continuing education in family medicine.

Multiple choice questions used in continuing medical education may require characteristics different from those used in tests and examinations. The questions of three continuing education exercise were assessed by 48 board certified family physicians. Each physician answered one third of the questions and then judged them on usefulness in patient management, as discriminators of quality of medical care, and on educational value. The relevance of each question was determined by a composite index based on these factors. The content of each question was independently analyzed by three physicians. Relevant questions tended to be those concerned with surgery, symptoms, and management, and those requiring more than simple factual recall. Questions on office management or concerning specific diagnoses were considered less relevant. Neither the manner of asking the question nor the severity of the illness appeared to influence relevance. This information should benefit those developing continuing education programs for family physicians, especially those designed for self-administered individual learning.

Education, Medical, Continuing↗