Brain SPECT: a controlled, blinded assessment of intra-reader and inter-reader agreement.

A detailed assessment of intra- and inter-reader variation in the interpretation of brain SPECT scans has been performed. A random sample was selected from scans performed at a community/teaching hospital in Seattle. Scans were interpreted independently by three experienced readers who were blinded to all patient information. Forty-eight scans were interpreted twice by each reader, for a total of 288 readings. Readers recorded detailed assessments of individual lesions and overall impressions using a standardized reporting form. Intra-observer agreement as reflected in per cent agreement for severity scores ranged from 65% to 100%. Intra-observer agreement on the 'overall impression' was very good for Alzheimer's pattern (kappa=0.73-1.00), and fair to good for the 'heterogeneous pattern' (kappa=0.30-0.63). Inter-observer agreement, as reflected in per cent agreement, ranged from 29% to 100%. Inter-observer agreement about the 'overall impression' was fair to moderate for Alzheimer's pattern (kappa=0.24-0.54) and was poor for the descriptors 'heterogeneous' and 'normal'. It is concluded that brain SPECT has great potential value in many important conditions. This study demonstrates a need for further work in the areas of pattern definition and reduction of observer variation.

Environmental chemical exposures and disturbances of heme synthesis.

Porphyrias are relatively uncommon inherited or acquired disorders in which clinical manifestations are attributable to a disturbance of heme synthesis (porphyrin metabolism), usually in association with endogenous or exogenous stressors. Porphyrias are characterized by elevations of heme precursors in blood, urine, and/or stool. A number of chemicals, particularly metals and halogenated hydrocarbons, induce disturbances of heme synthesis in experimental animals. Certain chemicals have also been linked to porphyria or porphyrinuria in humans, generally involving chronic industrial exposures or environmental exposures much higher than those usually encountered. A noteworthy example is the Turkish epidemic of porphyria cutanea tarda produced by accidental ingestion of wheat treated with the fungicide hexachlorobenzene. Measurements of excreted heme precursors have the potential to serve as biological markers for harmful but preclinical effects of certain chemical exposures; this potential warrants further research and applied field studies. It has been hypothesized that several otherwise unexplained chemical-associated illnesses, such as multiple chemical sensitivity syndrome, may represent mild chronic cases of porphyria or other acquired abnormalities in heme synthesis. This review concludes that, although it is reasonable to consider such hypotheses, there is currently no convincing evidence that these illnesses are mediated by a disturbance of heme synthesis; it is premature or unfounded to base clinical management on such explanations unless laboratory data are diagnostic for porphyria. This review discusses the limitations of laboratory measures of heme synthesis, and diagnostic guidelines are provided to assist in evaluating the symptomatic individual suspected of having a porphyria.

Immunologic, psychological, and neuropsychological factors in multiple chemical sensitivity. A controlled study.

OBJECTIVE: To examine the role of immunologic, psychological, and neuropsychological factors in multiple chemical sensitivity. DESIGN: Case-control comparison. SETTING: Community allergy practice (cases), university-based clinics for musculoskeletal injuries (controls). PARTICIPANTS: Forty-one patients with chemical sensitivity and 34 control patients with chronic musculoskeletal injuries. MAIN OUTCOME MEASURES: Immunologic measures included autoantibody titers, lymphocyte surface markers, and interleukin-1 generation by monocytes. Psychological evaluation included standardized measures of anxiety, depression, and somatization. RESULTS: Immunologic testing did not differentiate patients with chemical sensitivity from controls. The only difference noted (lower interleukin-1 generation among cases) appeared attributable to laboratory methods. Patients with chemical sensitivity reported greater prevalence of current anxiety or depressive disorder (44% versus 15%, P = 0.006). This difference, however, did not appear to precede the onset of chemical sensitivity, and 25% of chemically sensitive patients showed no significant current psychological disturbance. Cases reported significantly more "medically unexplained" physical symptoms before and after the onset of chemical sensitivity. When considering only symptoms that preceded chemical sensitivity, 25% of cases (and no controls) satisfied criteria for somatization disorder. Neuropsychological testing revealed no significant case-control differences. CONCLUSIONS: Immunologic testing failed to confirm findings from earlier uncontrolled studies, militating against proposed immunologic mechanisms. The decreased memory and concentration frequently described in multiple chemical sensitivity were not confirmed by brief neuropsychological testing. Psychological symptoms, although not necessarily etiologic, are a central component of chemical sensitivity.

Public cholesterol screening: motivation for participation, follow-up outcome, self-knowledge, and coronary heart disease risk factor intervention.

We used a mailed questionnaire and telephone interviews with 1717 shopping center screenees whose total serum cholesterol was greater than 200 mg/dl. Our specific aim was to assess the subjects' motivations for participation in cholesterol screening, their follow-up outcome, their self-knowledge, and any coronary heart disease risk factor intervention. Of 1717 questionnaires mailed, 507 (30%) were returned; 64 of 100 subjects randomly selected for telephone interview could be contacted, and 61 were interviewed. Responses to the questionnaire and telephone interview were congruent, indicating little self-selection response bias. Before the cholesterol screening, 50% and 67% of questionnaire and telephone interview subjects knew their cholesterol levels. The nine most commonly cited reasons for cholesterol screening participation were: a desire to "watch" health (72%), convenience (70%), low cost (64%), to recheck previously measured total cholesterol (54%), publicity (34%), curiosity (30%), a relative with premature coronary heart disease (27%), the subjects' obesity (26%), and a relative's high cholesterol level (25%). As a result of cholesterol screening, 65% and 63% of questionnaire and telephone interview subjects, respectively, followed up with their doctors; 67% and 56%, respectively, had total cholesterol remeasured, but 17% and 18%, respectively, were told to "do nothing." At their doctors' follow-up, 74% and 51% of questionnaire and telephone interview respondents, respectively, began a low-saturated fat, low-cholesterol diet; 10% and 15% started taking a cholesterol-lowering drug. As a result of cholesterol screening, 76% and 85% of questionnaire and telephone interview subjects, respectively, changed their diets; 78% and 84% lowered their dietary cholesterol intakes, 62% and 74% increased their fiber intakes, 49% and 57% tried to lose weight, and 44% and 43% increased their exercise. Of questionnaire subjects, 94% thought that by lowering cholesterol, coronary heart disease risk could be reduced; 95% had become more aware of cholesterol in the last 5 years. Of telephone interview subjects, 91% concluded that cholesterol screening had motivated them to reduce cholesterol levels. Public cholesterol screening is convenient, inexpensive, facilitates self-knowledge about cholesterol, stimulates follow-up, and motivates physician and subject-guided dietary changes to reduce cholesterol levels and coronary heart disease risk.

The psycho-social consequences of aircraft noise.

The paper describes and compares various methods of investigating the social disamentity caused by aircraft noise. These methods include social surveys,the analysis of complaints, and direct observation. Each has practical, political and statistical advantages and disadvantages. The effects of aircraft noise are also discussed and the conclusion is drawn that if social pressure continues to be applied, the technologists can and will quieten aircraft engines.

Scale design of metric rules and slide rules.

The design of metric draughtsmen's scale rules is discussed as if they were indicating instruments with straight scales. A minimum distance between marks of 1 mm is recommended and some suggestions for experimental designs are made. Slide rules are also considered with a view to improving their legibility.