Nicholas J. Birkett

Amitriptyline versus maprotiline in postherpetic neuralgia: a randomized, double-blind, crossover trial.

&NA; Amitriptyline (AT) relieves some patients with postherpetic neuralgia (PHN). Many patients suffer side effects and better therapies are necessary. The aim of this study was to evaluate the efficacy of maprotiline (MT) (noradrenergic) compared to AT (mixed noradrenergic and serotonergic) in this disorder. Thirty‐five patients entered a randomized, double‐blind, crossover trial of these two agents. We found that MT relieved PHN in many patients but was not as effective as AT. Side effects were troublesome with both agents. Relief of steady pain, brief pain and pain on tactile stimulation occurred. Four groups of responses were identified. Some patients reported relief with both agents, some with neither agent and others with only one of the drugs. Most patients were not depressed and analgesia was observed to occur without change in depression ratings in most patients who responded. This result provides evidence that in some patients AT may act via a selective noradrenergic mechanism in relieving PHN and that individuals may differ in the balance and type of neurotransmitters inhibiting pain. Selective noradrenergic agents may be effective if AT fails.

Estimates of global mortality attributable to particulate air pollution using satellite imagery

BACKGROUND Epidemiological studies of the health effects of air pollution have traditionally relied upon ground-monitoring stations to measure ambient concentrations. Satellite derived air pollution measures offer the advantage of providing global coverage. OBJECTIVE To undertake a global assessment of mortality associated with long-term exposure to fine particulate air pollution using remote sensing data. METHODS Global PM(2.5) exposure levels were derived from the MODIS and MISR satellite instruments. Relative risks and attributable fractions of mortality were modeled using previously developed concentration-response functions for the association between PM(2.5) and mortality. RESULTS The global fraction of adult mortality attributable to the anthropogenic component of PM(2.5) (95% CI) was 8.0% (5.3-10.5) for cardiopulmonary disease, 12.8% (5.9-18.5) for lung cancer, and 9.4% (6.6-11.8) for ischemic heart disease. CONCLUSION This study demonstrates the feasibility of using satellite derived pollution concentrations in assessing the population health impacts of air pollution at the global scale. This approach leads to global estimates of mortality attributable to PM(2.5) that are greater than those based on fixed site ground-level measures of urban PM(2.5), but more similar to estimates based on global chemical transport model simulations of anthropogenic PM(2.5).

Predicting exercise stage transitions over two consecutive 6-month periods : A test of the theory of planned behaviour in a population-based sample

OBJECTIVES To predict exercise stage transitions over two consecutive 6-month periods using the theory of planned behaviour (TPB). It was hypothesized that different social cognitive constructs would predict different stage transitions. DESIGN Prospective and longitudinal in order to predict multiple stage transitions over time. Assessments were made at baseline, 6 months and 1 year. METHOD Participants were a randomly selected population-based sample of 683 adults who completed two telephone interviews (baseline and 6 months) that assessed exercise stage, intention, perceived behavioural control, attitude, subjective norm, and social support, and a mailed survey (1 year) that assessed exercise stage. RESULTS Progression from pre-contemplation was predicted by intention, attitude and subjective norm; progression/regression from contemplation was predicted by intention, perceived behavioural control, attitude, and social support; progression/regression from preparation was predicted by intention and attitude; and regression from action/maintenance was predicted by intention, attitude and social support. CONCLUSIONS Different social cognitive constructs predicted different stage transitions, which indicates that exercise behaviour change may be represented by a series of stage transitions. Moreover, the TPB may be a useful model for highlighting the key social cognitive constructs that are important for exercise stage transitions.

The prognosis with postherpetic neuralgia.

One hundred and fifty-six patients with moderate to severe postherpetic neuralgia (PHN) were followed for up to 11 years. Nearly half of all patients were doing well at the final assessment (median 2 years) and more than half of these were on no therapy at this time. The most commonly used agents associated with a good outcome were antidepressants, topical capsaicin and analgesics of various kinds. Longer duration PHN appeared to have a worse prognosis. More of these patients were noted to be using some form of treatment at follow up. A group of patients seemed to follow a progressive course and were refractory to all treatments used in this study.

The Efficacy of Stage-Matched and Standard Public Health Materials for Promoting Physical Activity in the Workplace: The Physical Activity Workplace Study (PAWS)

Purpose. To compare the effects of stage-matched and standard print materials for physical activity (PA) change. Design. Participants were randomized into (1) a stage-matched intervention group (n = 165), (2) a standard intervention group (n = 176), or (3) a no-contact control group (n = 166). The stage-matched and standard intervention groups both received materials at baseline, 3 months, and 6 months. Assessments of all three groups were conducted at baseline, 6, and 12 months. Setting. Canadian worksites. Subjects. Employees (N = 507). Interventions. Five motivationally targeted booklets were developed for the stage-matched group. The standard group received Canadas Physical Activity Guide and handbook. Measures. The main dependent variable was PA, expressed as metabolic equivalent (MET) minutes and measured using the Godin Leisure-Time Exercise Questionnaire. Demographic characteristics and stages of change for PA were also assessed. Results. At 12 months mean weekly MET minutes for combined moderate and vigorous activity increased from baseline by 223, 67, and 78 for the stage-matched, standard, and control groups, respectively; however, differences were not significant (p > .05). Women in the stage-matched group over the 12-month period significantly increased their activity by 327 weekly MET minutes whereas the standard and control groups declined their activity (F = 3.01, p < .05). Conclusion. PA stage-matched materials delivered in the workplace are efficacious for women but not men. Future interventions should explore the use of these intervention materials in conjunction with multilevel strategies, and particular attention should be paid to possible gender differences.

Dietary risk factors for testicular carcinoma

Although testicular cancer is a relatively rare lesion, accounting for only 1.1% of all malignant neoplasms in males in Canada, it is the most common cancer among Canadian men 20–45 years of age. Knowledge of the causes of testicular cancer risk in general, and more specifically, its association with diet, remain limited. Data from 601 cases of testicular cancer and 744 population‐based controls collected in 8 of the 10 Canadian provinces between 1994–97 were used to explore the relationship between diet and testicular cancer risk. We systematically examined 17 food groups, 15 nutrients and 4 individual foods based on data collected through a 69‐item food‐frequency questionnaire. Our results suggest that high dairy product intake, in particular high intake of cheese (odds ratio [OR] = 1.87; 95% confidence interval [CI] 1.22–2.86; p‐trend < 0.001), is associated with an elevated risk of testicular cancer in Canadian males.

Intake of fruits and vegetables in smokers.

OBJECTIVES To examine intake of fruits and vegetables in smokers and non-smokers. DESIGN Secondary analysis using general linear modelling approaches. Food intake measured using a food frequency questionnaire approach. SETTING The community (the population of the province of Ontario, Canada). SUBJECTS Members of the general public (n = 38,000). RESULTS Smokers ate substantially less fruit and fruit juice then non-smokers with heavy smokers eating the least. Heavy smokers were between four and six times more likely to be eating less fruit than recommended. Similar but less marked differences were noted for vegetable intake. Smokers also obtained a larger part of their total caloric intake from fats. CONCLUSIONS While smoking cessation remains the primary target for lung cancer prevention, attention should also be given to dietary interventions in smokers in order to improve their nutrition. Such interventions might also be expected to reduce the risk of other cancers (e.g. colon cancer).

Dietary Intake of Benzo(a)pyrene and Risk of Esophageal Cancer in North of Iran

One etiologic factor for high incidence of esophageal squamous cell carcinoma (ESCC) in Golestan (Northeastern Iran) might be exposure to polycyclic aromatic hydrocarbons. We examined whether food and water are major sources of benzo(a)pyrene (BaP) exposure in this population. We used a dietary questionnaire to assess the daily intake of staple food (rice and bread) and water in 3 groups: 40 ESCC Golestan cases, 40 healthy subjects from the same area, and 40 healthy subjects from a low-risk area in Southern Iran. We measured, by high-performance liquid chromatography combined with fluorescence detection, the BaP concentration of bread, rice, and water in samples obtained from these 3 groups and calculated the daily intake of BaP. Mean BaP concentration of staple foods and water was similar and within standard levels in both areas, but the daily intake of BaP was higher in controls from the high-risk area than in controls from the low-risk area (91.4 vs. 70.6 ng/day, P < 0.01). In the multivariate regression analysis, having ESCC had no independent effect on BaP, whereas residence in the low-risk area was associated with a significant decrease in total BaP intake. Polycyclic aromatic hydrocarbons might, along with other risk factors, contribute to the high risk of ESCC in Golestan.

Cobalt and Chromium Levels in Blood and Urine Following Hip Resurfacing Arthroplasty with the Conserve Plus Implant

BACKGROUND The purpose of the present study was to determine cobalt and chromium ion levels in the blood and urine of patients in whom a modern-generation metal-on-metal hip resurfacing device had been implanted. METHODS A total of ninety-seven patients with a Conserve Plus metal-on-metal hip resurfacing implant were followed prospectively for two years. Cobalt and chromium levels in erythrocytes, serum, and urine were measured preoperatively as well as three, six, twelve, and twenty-four months postoperatively. RESULTS The median serum cobalt and chromium ion levels were 1.04 μg/L (range, 0.31 to 7.42 μg/L) and 2.00 μg/L (range, 0.28 to 10.49 μg/L), respectively, at one year after surgery and 1.08 μg/L (range, 0.44 to 7.13 μg/L) and 1.64 μg/L (range, 0.47 to 10.95 μg/L), respectively, at two years after surgery. The corresponding mean levels (and standard deviations) of serum cobalt and chromium were 1.68 ± 1.66 μg/L and 2.70 ± 2.22 μg/L, respectively, at one year after surgery and 1.79 ± 1.66 μg/L and 2.70 ± 2.37 μg/L, respectively, at two years after surgery. CONCLUSIONS These levels compare favorably with other published ion results for metal-on-metal hip resurfacing and replacement implants. No pseudotumors or other adverse soft-tissue reactions were encountered in our study population. Further research is needed to determine the clinical importance of increased cobalt and chromium ion levels in serum and urine following metal-on-metal hip resurfacing.

Cancer Incidence Patterns Among Chinese Immigrant Populations in Alberta

This study examines the incidence of cancer among Chinese immigrants to Alberta in comparison to the incidence in Canadian-born Alberta residents and in people of Chinese origin still living in China. Cancer cases among Chinese immigrants and Canadian-born Alberta residents were identified from the Alberta Cancer Registry (1974–1993). Incidence rates for Shanghai (1975–1992) were obtained from the International Agency for Research on Cancer (IARC) publications. Direct age-standardized incidence rates (ASIRs) were calculated using the “world standard population.” Descriptive analysis and Poisson regression modelling were employed to obtain the rate ratios for certain cancer sites among the three populations. For males, the overall incidence of cancer (excluding non-melanoma skin cancer) was lowest in Chinese immigrants while being similar in Canadian-born Alberta residents and Chinese living in Shanghai (197 vs. 224 and 232/100,000). For females, the overall incidence in Chinese immigrants was lower than Canadian-born Alberta residents but similar to that in Chinese living in Shanghai (154 vs 200 and 150/100,000). For cancers that are common in China (stomach and esophagus), the incidence rates for Chinese immigrants were more similar to those for Canadian-born residents than to rates for Shanghai. However, the incidence of liver cancer was very high in the immigrants, suggesting the possible presence of an initiating event during childhood or early adulthood. For cancers that are traditionally uncommon in China (breast and prostate), rates for immigrants were mid-way between those of the two comparison groups. This study supports observations that the risk of cancer in immigrants tends towards the risk of people in the new host country.