The Long-Term Mortality Effects Associated with Exposure to Particles and NOx in the Malmö Diet and Cancer Cohort

In this study, the long-term mortality effects associated with exposure to PM10 (particles with an aerodynamic diameter smaller than or equal to 10 µm), PM2.5 (particles with an aerodynamic diameter smaller than or equal to 2.5 µm), BC (black carbon), and NOx (nitrogen oxides) were analyzed in a cohort in southern Sweden during the period from 1991 to 2016. Participants (those residing in Malmö, Sweden, born between 1923 and 1950) were randomly recruited from 1991 to 1996. At enrollment, 30,438 participants underwent a health screening, which consisted of questionnaires about lifestyle and diet, a clinical examination, and blood sampling. Mortality data were retrieved from the Swedish National Cause of Death Register. The modeled concentrations of PM10, PM2.5, BC, and NOx at the cohort participants' home addresses were used to assess air pollution exposure. Cox proportional hazard models were used to estimate the associations between long-term exposure to PM10, PM2.5, BC, and NOx and the time until death among the participants during the period from 1991 to 2016. The hazard ratios (HRs) associated with an interquartile range (IQR) increase in each air pollutant were calculated based on the exposure lag windows of the same year (lag0), 1-5 years (lag1-5), and 6-10 years (lag6-10). Three models were used with varying adjustments for possible confounders including both single-pollutant estimates and two-pollutant estimates. With adjustments for all covariates, the HRs for PM10, PM2.5, BC, and NOx in the single-pollutant models at lag1-5 were 1.06 (95% CI: 1.02-1.11), 1.01 (95% CI: 0.95-1.08), 1.07 (95% CI: 1.04-1.11), and 1.11 (95% CI: 1.07-1.16) per IQR increase, respectively. The HRs, in most cases, decreased with the inclusion of a larger number of covariates in the models. The most robust associations were shown for NOx, with statistically significant positive HRs in all the models. An overall conclusion is that road traffic-related pollutants had a significant association with mortality in the cohort.

Long-Term Exposure to Transportation Noise and Ischemic Heart Disease: A Pooled Analysis of Nine Scandinavian Cohorts

BACKGROUND

Transportation noise may induce cardiovascular disease, but the public health implications are unclear.

OBJECTIVES

The study aimed to assess exposure-response relationships for different transportation noise sources and ischemic heart disease (IHD), including subtypes.

METHODS

Pooled analyses were performed of nine cohorts from Denmark and Sweden, together including 132,801 subjects. Time-weighted long-term exposure to road, railway, and aircraft noise, as well as air pollution, was estimated based on residential histories. Hazard ratios (HRs) were calculated using Cox proportional hazards models following adjustment for lifestyle and socioeconomic risk factors.

RESULTS

A total of 22,459 incident cases of IHD were identified during follow-up from national patient and mortality registers, including 7,682 cases of myocardial infarction. The adjusted HR for IHD was 1.03 [95% confidence interval (CI) 1.00, 1.05] per 10 dB Lden for both road and railway noise exposure during 5 y prior to the event. Higher risks were indicated for IHD excluding angina pectoris cases, with HRs of 1.06 (95% CI: 1.03, 1.08) and 1.05 (95% CI: 1.01, 1.08) per 10 dB Lden for road and railway noise, respectively. Corresponding HRs for myocardial infarction were 1.02 (95% CI: 0.99, 1.05) and 1.04 (95% CI: 0.99, 1.08). Increased risks were observed for aircraft noise but without clear exposure-response relations. A threshold at around 55 dB Lden was suggested in the exposure-response relation for road traffic noise and IHD.

DISCUSSION

Exposure to road, railway, and aircraft noise in the prior 5 y was associated with an increased risk of IHD, particularly after exclusion of angina pectoris cases, which are less well identified in the registries. https://doi.org/10.1289/EHP10745.

Estimated public health benefits of a low-emission zone in Malmö, Sweden

Air pollution is one of the leading causes of morbidity and mortality worldwide. Low-emission zones (LEZ) have been increasingly implemented in cities throughout Europe as a measure to reduce the adverse health effects and premature deaths associated with traffic-related air pollution. In the present study, a health impact analysis was conducted to estimate the effect of a hypothetical LEZ on mortality and morbidity in Malmö, Sweden. Baseline health statistics were gathered from health registers and applied to each resident according to individual-level data on age and/or sex. Concentration-response parameters were derived from current epidemiological literature, specifically meta-analyses. A Gaussian dispersion model (AERMOD) combined with a detailed emission database was used to calculate NO₂ emissions from traffic, which could be applied on an individual-level using data on each person's residential coordinates. The adjusted exposure scenario replaced all vehicles on municipal roads having Euro 5 or lower emission standards with Euro 6 equivalents. This LEZ would, on average, decrease NO₂ concentrations by 13.4%, preventing an estimated 9-26 deaths in Malmö each year. Additionally, 12 respiratory disease hospitalizations, 8 childhood asthma cases, and 9 cases of hypertensive disorders of pregnancy were estimated to be avoided annually. These results suggest that LEZs can effectively improve air quality, reduce greenhouse gas emissions, and safeguard public health.

Low-density lipoprotein cholesterol reduction with evolocumab and its use in clinical practice: evidence from Swedish national register data

Background/Introduction

Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors reduce low density lipoprotein cholesterol (LDL-C) levels by around 50% to 60%, and the risk of cardiovascular events in patients with atherosclerotic cardiovascular disease (ASCVD) in randomized clinical trials. Data on LDL-C reduction with PCSK9 inhibitors and its use in clinical practice is lacking.

Purpose

Assess LDL-C reduction with the PCSK9 inhibitor evolocumab and its use in clinical practice in Sweden.

Methods

Population-based, retrospective, longitudinal, observational study of patients initiating evolocumab treatment between July 2015 and May 2020. Patients undergoing lipoprotein apheresis were excluded. Patient level data was obtained from national diagnosis and pharmaceutical registers (covering 100% of the Swedish population), and electronic health records (covering 60% of the Swedish population). The use of evolocumab was assessed based on persistence with and adherence to treatment. Patients were defined as being persistent if they were still taking evolocumab 12 months after treatment initiation. Medication gaps were allowed until a last gap of ≥56 days. Patients were defined as being adherent if the proportion of days covered (PDC) by the drug was ≥80% during that same period. Mean LDL-C reduction was estimated 3 months after evolocumab treatment initiation, using a Generalized Least Squares regression model.

Results

Overall, 2341 patients were included in the analysis, with a median follow-up of 376 days. Median age was 65 years, 43% were women, 79% had a history of ASCVD and, among them, 94% had had a coronary event and 24% had diabetes. 44% of the patients had LDL-C available. Median LDL-C was 4.1 mmol/L and 64% of the patients were receiving oral lipid-lowering treatment (LLT). After 12 months of treatment, 76% of the patients were persistent with evolocumab. In these patients, median PDC over 12 months was 93%, with 86% of these patients being adherent (PDC ≥80%). In the overall population (n=724), the estimated mean LDL-C reduction with evolocumab at 3 months was 48% (2.1 mmol/L, from 4.4 mmol/L at baseline). In patients who were adherent to evolocumab during the first 6 months (n=567), LDL-C reduction was 53% (2.2 mmol/L, from 4.3 mmol/L at baseline) (see figure). In patients who were adherent to both evolocumab and oral LLT (PDC ≥80% over a period of 3 months before and after evolocumab initiation) (n=186), LDL-C reduction was 59% (2.1 mmol/L, from 3.6 mmol/L at baseline). The estimated mean LDL-C reduction remained stable over a 6-month period.

Conclusions

Persistence with and adherence to evolocumab treatment were high over 12 months. LDL-C reduction with evolocumab in clinical practice was similar to that observed in randomized clinical trials and remained stable over 6 months. At evolocumab treatment initiation, many patients had high LDL-C levels and underused oral LLT, potentially due to statin intolerance.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Amgen

Long-term assessment and target achievement of LDL-C and systolic blood pressure in primary care after acute coronary syndrome

Background

Hospital-based cardiac rehabilitation and risk factor control decreases the risk of recurrent events after acute coronary syndrome (ACS). Little is known on long-term assessment and target achievement after referral to primary care. Patients with diabetes, regardless of ACS, have yearly follow-up visits in primary care, whereas there is no structured follow-up after ACS for patients without diabetes.

Purpose

To describe long-term assessment and target achievement of LDL-C and systolic blood pressure (SBP) in ACS patients after referral to primary care. Further, to compare patients with and without diabetes at the time of index ACS.

Methods

A non-interventional population-based observational study of patients with first ever ACS in a Swedish region with 390,000 inhabitants. Data on clinical measurements after ACS were collected from the electronic medical records between 2012 and 2020. Patients were followed until new ACS event, death, moving out of the county, or end of study. Target levels studied were LDL-C <1.8 mmol/L and SBP <140 mmHg. The same assessments with the addition of target levels of HbA1c ≤70 mmol/mol were evaluated in patients with diabetes.

Results

Median follow-up was 2.9 years (inter quartile range [IQR]: 1.0–5.4) and 4,733 patients were detected. Median age was 72 years (IQR 63–80) and 34% were female. Follow-up data were available for 3,579 (76%) patients any time during the first, 2,891 (61%) during the second, and 2,308 (49%) during the third year after the index ACS event. The number of patients with diabetes was 1311 (28%), and of these 921, 723, and 562 could be followed for the first, second, and third year. During the first three years, 898 (19%) of all patients with available follow-up died.

The proportion of patients with assessments of LDL-C and SBP declined for each year of follow-up and target achievement was low (Table). Among patients with diabetes a larger proportion had measurements for LDL-C and SBP, while the target achievement was similar to that of the whole study population. HbA1c was measured equally frequently as SBP and was at target in 81% of patients with diabetes during the three years of follow-up (Table).

Conclusion

The proportion of patients with follow-up assessment and measurements in primary care declined each year after the index ACS event. Patients with diabetes had more frequent LDL-C and SBP measurements but the same low target achievement after an ACS compared with patients without diabetes. This could potentially be due to an increased focus on glycaemic control at these visits. A structured long-term follow-up for ACS patients in primary care might improve both assessment and target achievement and prevent recurrent ACS events.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): AmgenSwedish Heart Lung Foundation

Associations between long-term exposure to low-level air pollution and risk of chronic kidney disease-findings from the Malmö Diet and Cancer cohort

BACKGROUND

Associations between air pollution and chronic kidney disease (CKD) have been reported, but studies at low exposure levels and relevant exposure time windows are still warranted. This study investigated clinical CKD at low air pollution levels in the Swedish Malmö Diet and Cancer Cohort in different exposure time windows.

METHODS

This study included 30,396 individuals, aged 45-74 at enrollment 1991-1996. Individual annual average residential outdoor PM_2.5, PM₁₀, nitrogen oxides (NO_x), and black carbon (BC) were assigned using dispersion models from enrollment to 2016. Diagnoses of incident CKD were retrieved from national registries. Cox proportional hazards models were used to obtain hazard ratios (HRs) for CKD in relation to three time-dependent exposure time windows: exposure at concurrent year (lag 0), mean exposure in the 1-5 or 6-10 preceding years (lag 1-5 and lag 6-10), and baseline exposure.

RESULTS

During the study period, the average annual residential exposures were 16 μg/m³ for PM₁₀, 11 μg/m³ for PM_2.5, 26 μg/m³ for NO_x, and 0.97 μg/m³ for BC. For lag 1-5 and lag 6-10 exposure, significantly elevated HRs for incident CKD were found for total PM₁₀:1.13 (95% CI: 1.01-1.26) and 1.22 (1.06-1.41); NO_x: 1.19 (1.07-1.33) and 1.13 (1.02-1.25) and BC: 1.12 (1.03-1.22) and 1.11 (1.02-1.21) per interquartile range increase in exposure. For total PM_2.5 the positive associations of 1.12 (0.97-1.31) and 1.16 (0.98-1.36) were not significant. For baseline or lag 0 exposure there were significant associations only for NO_x and BC, not for PM.

CONCLUSION

Residential exposure to outdoor air pollution was associated with increased risk of incident CKD at relatively low exposure levels. Average long-term exposure was more clearly associated with CKD than current exposure or exposure at recruitment. Our findings imply that the health effects of low-level air pollution on CKD are considerable.

A real-world analysis of characteristics and lipid-lowering therapy use in patients initiating treatment with evolocumab in Sweden

Background/Introduction

Proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors reduce low-density lipoprotein cholesterol (LDL-C) levels and the risk of cardiovascular events in patients with atherosclerotic cardiovascular disease (ASCVD) in clinical trials. In January 2019, evolocumab reimbursement recommendation in Sweden was broadened to include patients on maximally tolerated oral lipid-lowering therapy (LLT) and either ASCVD and LDL-C ≥2.5 mmol/L, or familial hypercholesterolemia (FH) with no ASCVD and LDL-C ≥3.0 mmol/L.

Purpose

Describe characteristics and LLT use in patients initiating treatment with evolocumab in the context of the 2019 reimbursement recommendation in Sweden.

Methods

Cross-sectional, population-based, retrospective, observational study of patients initiating treatment with evolocumab between January 2019 and June 2020. Data were obtained from national healthcare registers and electronic medical records, covering more than half of the Swedish population.

Results

Out of 1560 patients included, 41% had LDL-C available ≤3 months prior to treatment initiation with evolocumab. Among those with LDL-C available, 79% had ASCVD and 19% had definite, probable or possible FH with no ASCVD. Mean pre-treatment LDL-C levels were 3.7 and 5.0 mmol/L for patients with ASCVD, and FH with no ASCVD, respectively. Most of the patients, 84.6% and 80.0%, respectively, had been ever treated with both statins and ezetimibe. However, 28.0% and 38.3% of them, respectively, were not on oral LLT at the time of treatment initiation with evolocumab. Patient characteristics and LLT use are presented in Table 1.

Conclusions

Patients initiating treatment with evolocumab in Sweden had pre-treatment LDL-C levels far from treatment targets, despite being at very high risk for cardiovascular events. Most of the patients had been treated with both statins and ezetimibe in the past. However, almost a third of them were not using oral LLT at the time of treatment initiation with evolocumab. The conditions in the 2019 evolocumab reimbursement recommendation in Sweden were generally met.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Amgen

Long-term exposure to air pollution and atherosclerosis in the carotid arteries in the Malmö diet and cancer cohort

BACKGROUND

Long-term exposure to air pollution increases the risk of cardiovascular morbidity and mortality, but the mechanisms are not fully known. Current evidence suggests that air pollution exposure contributes to the development of atherosclerosis. There are few studies investigating associations between air pollution and carotid plaques, a well-known precursor of cardiovascular disease.

METHODS

A Swedish population-based cohort (aged 45-64 years at recruitment) was randomly selected from the Malmö Diet and Cancer study between 1991 and 1994, of which 6103 participants underwent ultrasound examination of the right carotid artery to determine carotid plaque presence and carotid intima media thickness (CIMT). Participants were assigned individual residential air pollution exposure (source-specific PM_2.5, PM₁₀, NO_x, BC) at recruitment from Gaussian dispersion models. Logistic and linear regression models, adjusted for potential confounders and cardiovascular risk factors, were used to investigate associations between air pollutants and prevalence of carotid plaques, and CIMT, respectively.

RESULTS

The prevalence of carotid plaques was 35%. The mean levels of PM_2.5 and PM₁₀ at recruitment were 11 and 14 μg/m³, most of which was due to long range transport. The exposure contrast within the cohort was relatively low. PM_2.5 exposure was associated with carotid plaques in a model including age and sex only (OR 1.10 (95% CI 1.01-1.20) per 1 μg/m³), but after adjustment for cardiovascular risk factors and socioeconomic status (SES) the association was weak and not significant (OR 1.05 (95% CI 0.96-1.16) per 1 μg/m³). The pattern was similar for PM₁₀ and NO_x exposure. Associations between air pollutants and plaques were slightly stronger for long-term residents and in younger participants with hypertension. There was no clear linear trend between air pollution exposure and plaque prevalence. Non-significant slightly positive associations were seen between air pollution exposures and CIMT.

CONCLUSIONS

In this large, well-controlled cross-sectional study at low exposure levels we found no significant associations between air pollution exposures and subclinical atherosclerosis in the carotid arteries, after adjusting for cardiovascular risk factors and SES. Further epidemiological studies of air pollution and intermediate outcomes are needed to explain the link between air pollution and cardiovascular events.

Particle concentrations, dispersion modelling and evaluation in southern Sweden

Health impact assessments of differential air pollution rely on epidemiologically established relationships between concentration levels where people are exposed and adverse health outcomes. To assess air pollution concentrations, land use regression is commonly used. However, an alternative tool is dispersion modelling, where a detailed inventory of pollution sources together with meteorological data drives calculations of compound dispersion. With this, both spatial and temporal variation can be assessed. In this study, we evaluated results of a Gaussian dispersion model applied to an emissions inventory for Scania, the southernmost county in Sweden. The dispersion considered was particulate matter of aerodynamic diameter < 10 µm (PM10), particulate matter of aerodynamic diameter < 2.5 µm (PM2.5) and black carbon (BC) during an 11-year period (2000–2011). Mean concentrations and 95th percentiles expressed in µg/m3 ranged from 10.1 to 12.6 and 16.6 to 20.7 for PM2.5 and from 14.0 to 18.8 and 22.6 to 27.0 for PM10, respectively. Seven monitoring stations were used for evaluation. Correlations (R2) ranged from 0.44 to 0.86 for PM2.5 (mean bias from − 9.0 to 0.1 µg/m3) and from 0.46 to 0.83 for PM10 (mean bias − 6.1 to 3.5 µg/m3). An evaluated database of PM and BC concentrations for Scania is now available for future exposure assessment projects. Calculations were based on a well-known dispersion model with detailed emission data as input. The evaluation showed correlation coefficients for PM in line with previous literature. The data on PM10, PM2.5 and BC concentrations will, therefore, be used in subsequent studies, epidemiological as well as health impact assessments.

Evaluating reflective practice groups in a mental health context: Swedish translation and psychometric evaluation of the clinical supervision evaluation questionnaire

BACKGROUND

Implementation of reflective practice groups in psychiatric and mental health contexts might improve the quality of care through promoting self-awareness, clinical insight, and facilitating stress management and team building. There is a need for valid and reliable instruments to test the outcomes of reflective practice groups in the mental health context. This study aimed to test the validity and reliability of the Swedish version of the Clinical Supervision Evaluation Questionnaire.

METHODS

The instrument was translated from English to Swedish using a translation and back-translation procedure. Data for the calculation of content validity was collected from an expert group. Data for the reliability analysis was collected from rehabilitation assistants and ward managers participating in reflective practice groups (n = 20). Content validity was measured by computing a content validity index. Construct validity was assessed by calculating the corrected item-total correlation statistics. Reliability was evaluated by analysing the Cronbach's alpha coefficient, the intraclass correlation coefficient and inter-item correlations.

RESULTS

The content validity index for the scale as a whole was 0.94. Item-total correlations ranged between 0.23 and 0.81, and deletion of an item did not notably improve Cronbach's alpha. Cronbach's alpha for the scale was 0.89. The intraclass correlation coefficient for single measures was 0.35. The mean inter-item correlation was .37.

CONCLUSION

The Swedish version of the Supervision Evaluation Questionnaire has a degree of reliability and validity that is comparable to the original version in English, indicating that it can be used as an assessment of reflective practice groups in the mental health context.

Estimated health benefits of exhaust free transport in the city of Malmö, Southern Sweden

Air pollution is responsible for one in eight premature deaths worldwide, and thereby a major threat to human health. Health impact assessments of hypothetic changes in air pollution concentrations can be used as a mean of assessing the health impacts of policy, plans and projects, and support decision-makers in choices to prevent disease. The aim of this study was to estimate health impacts attributable to a hypothetical decrease in air pollution concentrations in the city of Malmö in Southern Sweden corresponding to a policy on-road transportations without tail-pipe emissions in the municipality. We used air pollution data modelled for each of the 326,092 inhabitants in Malmö by a Gaussian dispersion model combined with an emission database with >40,000 sources. The dispersion model calculates Nitrogen Oxides (NO_x) (later transformed into Nitrogen Dioxide (NO₂)) and particulate matter with an aerodynamic diameter < 2.5 μg/m³ (PM_2.5) with high spatial and temporal resolution (85 m and 1 h, respectively). The average individual reduction was 5.1 (ranging from 0.6 to 11.8) μg/m³ in NO_2, which would prevent 55 (2% of all deaths) to 93 (4%) deaths annually, depending on dose-response function used. Furthermore, we estimate that the NO₂ reduction would result in 21 (6%) fewer cases of incident asthma in children, 95 (10%) fewer children with bronchitis every year, 30 (1%) fewer hospital admissions for respiratory disease, 87(4%) fewer dementia cases, and 11(11%) fewer cases of preeclampsia every year. The average reduction in PM_2.5 of 0.6 (ranging from 0.1 till 1.7) μg/m³ would mean that 2729 (0.3%) work days would not be lost due to sick-days and that there would be 16,472 fewer restricted activity days (0.3%) that year had all on-road transportations been without tail-pipe emissions. Even though the estimates are sensitive to the dose-response functions used and to exposure misclassification errors, even the most conservative estimate of the number of prevented deaths is 7 times larger than the annual traffic fatalities in Malmö, indicating a substantial possibility to reduce the health burden attributed to tail-pipe emissions in the study area.

Targeted proteomic analysis of habitual coffee consumption

BACKGROUND

Coffee drinking has been implicated in mortality and a variety of diseases but potential mechanisms underlying these associations are unclear. Large-scale systems epidemiological approaches may offer novel insights to mechanisms underlying associations of coffee with health.

OBJECTIVE

We performed an analysis of known and novel protein markers linked to cardiovascular disease and their association with habitual coffee intake in the Prospective Study of the Vasculature in Uppsala Seniors (PIVUS, n = 816) and followed up top proteins in the Uppsala Longitudinal Study of Adult Men (ULSAM, n = 635) and EpiHealth (n = 2418).

METHODS

In PIVUS and ULSAM, coffee intake was measured by 7-day dietary records whilst a computer-based food frequency questionnaire was used in EpiHealth. Levels of up to 80 proteins were assessed in plasma by a proximity extension assay.

RESULTS

Four protein-coffee associations adjusted for age, sex, smoking and BMI, met statistical significance in PIVUS (FDR < 5%, P < 2.31 × 10^-3 ): leptin (LEP), chitinase-3-like protein 1 (CHI3L), tumour necrosis factor (TNF) receptor 6 and TNF-related apoptosis-inducing ligand. The inverse association between coffee intake and LEP replicated in ULSAM (β, -0.042 SD per cup of coffee, P = 0.028) and EpiHealth (β, -0.025 SD per time of coffee, P = 0.004). The negative coffee-CHI3L association replicated in EpiHealth (β, -0.07, P = 1.15 × 10^-7 ), but not in ULSAM (β, -0.034, P = 0.16).

CONCLUSIONS

The current study supports an inverse association between coffee intake and plasma LEP and CHI3L1 levels. The coffee-CHI3L1 association is novel and warrants further investigation given links between CHI3L1 and health conditions that are also potentially influenced by coffee.

Interconnectivity imaged in three dimensions: Nano-particulate silica-hydrogel structure revealed using electron tomography

We have used Electron Tomography (ET) to reveal the detailed three-dimensional structure of particulate hydrogels, a material category common in e.g. controlled release, food science, battery and biomedical applications. A full understanding of the transport properties of these gels requires knowledge about the pore structure and in particular the interconnectivity in three dimensions, since the transport takes the path of lowest resistance. The image series for ET were recorded using High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM). We have studied three different particulate silica hydrogels based on primary particles with sizes ranging from 3.6nm to 22nm and with pore-size averages from 18nm to 310nm. Here, we highlight the nanostructure of the particle network and the interpenetrating pore network in two and three dimensions. The interconnectivity and distribution of width of the porous channels were obtained from the three-dimensional tomography studies while they cannot unambiguously be obtained from the two-dimensional data. Using ET, we compared the interconnectivity and accessible pore volume fraction as a function of pore size, based on direct images on the nanoscale of three different hydrogels. From this comparison, it was clear that the finest of the gels differentiated from the other two. Despite the almost identical flow properties of the two finer gels, they showed large differences concerning the accessible pore volume fraction for probes corresponding to their (two-dimensional) mean pore size. Using 2D pore size data, the finest gel provided an accessible pore volume fraction of over 90%, but for the other two gels the equivalent was only 10-20%. However, all the gels provided an accessible pore volume fraction of 30-40% when taking the third dimension into account.

Perceptions of participating in high-intensity functional exercise among older people dependent in activities of daily living (ADL)

The purpose of the study was to evaluate how older people, dependent in ADL perceive their participation in a high-intensity, functional exercise program compared to the perceptions of those participating in a control activity. Forty-eight older people living in residential care facilities answered a questionnaire about their perceptions of participating in an activity for three months. They were aged 65-98, had a mean score of 24 on Mini Mental State Examination (MMSE) and 14 on Barthel ADL Index. The participants had been randomized to exercise (n=20) or control activity (n=28). Differences in responses between exercise and control activity were evaluated using logistic and ordinal regression analyses. The results show that a majority of the exercise group perceived positive changes in lower limb strength, balance, and in the ability to move more safely and securely compared to a minority of the control group (p<0.001). Significantly more respondents in the exercise activity answered that they felt less tired due to the activity (p=0.027) and that they prioritized this activity above other activities (p=0.010). More exercise participants reported that meeting for three months was too short, and fewer that it was too long compared to the control group (p=0.038). This study shows that older people living in residential care facilities, dependent in ADL, and with mild or no cognitive impairment had positive perceptions about participating in high-intensity functional exercise. The findings support the use of a high-intensity exercise program in this population of older people.

An in vivo comparison of hip structure analysis (HSA) with measurements obtained by QCT

SUMMARY

In a population of elderly women, bone cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), section modulus (Z), femoral neck axis length (FNAL), and width measured with hip structure analysis (HSA) on dual-energy x-ray absorptiometry (DXA) images in the femoral neck and trochanteric regions are highly correlated to quantitative computed tomography (QCT) measurements.

INTRODUCTION

HSA is a method of obtaining measurements of proximal femur structure using 2D DXA technology. This study was designed to examine the correlations between HSA measurements and 3D QCT.

METHODS

Forty-one women (mean age, 82.8 ± 2.5 years) were measured using DXA and a 64-slice CT scanner (1 mm slice thickness, 0.29 mm in plane resolution). HSA parameters were calculated at the narrow neck (NN) and trochanteric (IT) regions on the DXA image. These regions were then translated to anatomically equivalent regions on the QCT dataset by co-registering the DXA image and QCT dataset using four DXA images acquired at different angles.

RESULTS

At the NN and IT regions, high linear correlations were measured between HSA and QCT for CSA r = 0.95 and 0.93, CSMI r = 0.94 and 0.93, and Z r = 0.93 and 0.89, respectively. All correlations were highly significant (p < 0.001), but there were differences in slope and offset between the two techniques, at least in part due to differences in calibration between the two techniques. FNAL and width of the bone at the NN and IT regions, physical measurements independent of the calibration, were highly correlated (r = 0.90-0.95, p < 0.001) and had slopes close to 1.0 (range, 0.978 to 1.003).

CONCLUSION

CSA, CSMI, Z, FNAL, and width measured by HSA correlate highly to high-resolution QCT.

Comparison of QCT-derived and DXA-derived areal bone mineral density and T scores

Two-dimensional areal bone mineral density (aBMD) of the proximal femur measured by three-dimensional quantitative computed tomography (QCT) in 91 elderly women was compared to dual-energy X-ray absorptiometry (DXA) aBMD results measured in the same patients. The measurements were highly correlated, though QCT aBMD values were marginally lower in absolute units. Transformation of the QCT aBMD values to T score values using National Health and Nutrition Examination Survey (NHANES) DXA-derived reference data improved agreement and clinical utility.

INTRODUCTION

World Health Organization guidelines promulgate aBMD (g cm(-2)) measurement of the proximal femur for the diagnosis of bone fragility. In recent years, there has been increasing interest in QCT to facilitate understanding of three-dimensional bone structure and strength.

OBJECTIVE

To assist in comparison of QCT-derived data with DXA aBMD results, a technique for deriving aBMD from QCT measurements has been developed.

METHODS

To test the validity of the QCT method, 91 elderly females were scanned on both DXA and CT scanners. QCT-derived DXA equivalent aBMD (QCT(DXA) aBMD) was calculated using CTXA Hip software (Mindways Software Inc., Austin, TX, USA) and compared to DXA-derived aBMD results.

RESULTS

Test retest analysis indicated lower root mean square (RMS) errors for CTXA; F test between CTXA and DXA was significantly different at femoral neck (FN) and trochanter (TR) (p < 0.05). QCT underestimates DXA values by 0.02 +/- 0.05 g cm(-2) (total hip, TH), 0.01 +/- 0.04 g cm(-2) (FN), 0.03 +/- 0.07 g cm(-2) (inter-trochanter, IT), and 0.02 +/- 0.05 g cm(-2) (TR). The RMS errors (standard error of estimate) between QCT and DXA T scores for TH, FN, IT, and TR were 0.36, 0.40, 0.39, and 0.49, respectively.

CONCLUSIONS

This study shows that results from QCT aBMD appropriately adjusted can be evaluated against NHANES reference data to diagnose osteoporosis.

Defocus convergent beam electron diffraction analysis of dislocations in mullite

Burgers vectors of matrix dislocations in mullite have been determined by the defocus large-angle convergent beam electron diffraction technique. Vectors of the types [100], [010], [110] and [112] were identified. These Burgers vectors are discussed in relation to the open channels and the oxygen vacancy distribution in the mullite structure. It is suggested that a short-range ordering of oxygen vacancies may account for a Burgers vector of the type [112].

A study of spatial resolution in pollution exposure modelling

Background

This study is part of several ongoing projects concerning epidemiological research into the effects on health of exposure to air pollutants in the region of Scania, southern Sweden. The aim is to investigate the optimal spatial resolution, with respect to temporal resolution, for a pollutant database of NO_x-values which will be used mainly for epidemiological studies with durations of days, weeks or longer periods. The fact that a pollutant database has a fixed spatial resolution makes the choice critical for the future use of the database.

Results

The results from the study showed that the accuracy between the modelled concentrations of the reference grid with high spatial resolution (100 m), denoted the fine grid, and the coarser grids (200, 400, 800 and 1600 meters) improved with increasing spatial resolution. When the pollutant values were aggregated in time (from hours to days and weeks) the disagreement between the fine grid and the coarser grids were significantly reduced. The results also illustrate a considerable difference in optimal spatial resolution depending on the characteristic of the study area (rural or urban areas). To estimate the accuracy of the modelled values comparison were made with measured NO_x values. The mean difference between the modelled and the measured value were 0.6 μg/m³ and the standard deviation 5.9 μg/m³ for the daily difference.

Conclusion

The choice of spatial resolution should not considerably deteriorate the accuracy of the modelled NO_x values. Considering the comparison between modelled and measured values we estimate that an error due to coarse resolution greater than 1 μg/m³ is inadvisable if a time resolution of one day is used. Based on the study of different spatial resolutions we conclude that for urban areas a spatial resolution of 200–400 m is suitable; and for rural areas the spatial resolution could be coarser (about 1600 m). This implies that we should develop a pollutant database that allows different spatial resolution for urban and rural areas.

Children's exposure to nitrogen dioxide in Sweden: investigating environmental injustice in an egalitarian country

STUDY OBJECTIVE

Prior studies have shown that children are particularly sensitive to air pollution. This study examined whether children of low socioeconomic status suffered greater exposure to outdoor nitrogen dioxide than more affluent ones, both at their place of residence and at school, in a country with widespread state intervention for social equity.

DESIGN

Local scale data on outdoor nitrogen dioxide obtained from a validated air pollution model were analysed, along with all school children accurately geocoded to their building of residence and school.

PARTICIPANTS

All 29,133 children in grades one through nine (aged 7 to 15 years) residing and attending school in Malmö, Sweden, in 2001.

MAIN RESULTS

Defining the socioeconomic status of children according to the mean income in their residential building, the spatial scan statistic technique allowed the authors to identify eight statistically significant clusters of low socioeconomic status children, all of which were located in the most polluted areas of Malmö. Four clusters of high socioeconomic status children were found, all of them located in the least polluted areas. The neighbourhood socioeconomic status better predicted the nitrogen dioxide exposure of children than the socioeconomic status of their building of residence. Exposure to nitrogen dioxide at the place of residence and school of attendance regularly increased as the socioeconomic status of a child's neighbourhood of residence decreased.

CONCLUSIONS

Evidence of environmental injustice was found, even in a country noted for its egalitarian welfare state. Enforcement of environmental regulations may be necessary to achieve a higher level of environmental equity.

Are associations between socio-economic characteristics and exposure to air pollution a question of study area size? An example from Scania, Sweden

BACKGROUND

Numerous studies have shown that exposure to air pollutants in the area of residence and the socio-economic status of an individual may be related. Therefore, when conducting an epidemiological study on the health effect of air pollution, socio-economy may act as a confounding factor. In this paper we examine to what extent socio-economic status and concentrations of NO2 in the county/region of Scania, southern Sweden, are associated and if such associations between these factors differ when studying them at county or city level. To perform this study we used high-resolution census data and modelled the annual exposure to NO2 using an emission database, a dispersion modelling program and a geographical information system (GIS).

RESULTS

The results from this study confirm that socio-economic status and the levels of NO2 in the area of residence are associated in some cities. The associations vary considerably between cities within the same county (Scania). Even for cities of similar sizes and population bases the associations observed are different. Studying the cities together or separately yields contradictory results, especially when education is used as a socio-economic indicator.

CONCLUSION

Four conclusions have been drawn from the results of this study. 1) Adjusting for socio-economy is important when investigating the health effects of air pollution. 2) The county of Scania seems to be heterogeneous regarding the association between air pollution and socio-economy. 3) The relationship between air pollution and socio-economy differs in the five cities included in our study, depending on whether they are analysed separately or together. It is therefore inadvisable to determine and analyse associations between socio-economy and exposure to air pollutants on county level. This study indicates that the size and choice of study area is of great importance. 4) The selection of socio-economic indices (in this study: country of birth and education level) is important.

Lack of insulin-like growth factor binding protein-3 protease activation by venous cannulation

Disruption of the endothelium activates thrombogenic and fibrinolytic enzymes that cleave insulin-like growth factor binding protein-3 (IGFBP-3) in vitro. The aim of the present human study was to determine whether blood sampling, i.e., venous stasis and cannulation increase IGFBP-3 proteolysis before and/or after surgery by activating these enzymes. Serum samples obtained immediately after cannulation were compared with samples obtained from a previously inserted venous catheter. Cannulation did not increase serum IGFBP-3 proteolytic activity pre- and post-operatively, as determined by in vitro degradation of 125I-IGFBP-3. Furthermore, there was no effect on in vivo IGFBP-3 fragmentation assessed by western immunoblot. In addition, a standardized venous stasis did not affect IGFBP-3 proteolytic activity or fragmentation. Comparison of IGFBP-3 proteolytic activity before and after surgery demonstrated a significant post-operative increase. However, this could not be demonstrated immediately after the initial cannulation, due to a large individual variation at this time-point before surgery.

A new mathematical model for chemotactic bacterial colony growth

A new continuum model for the growth of a single species biofilm is proposed. The geometry of the biofilm is described by the interface between the biomass and the surrounding liquid. Nutrient transport is given by the solution of a semi-linear Poisson equation. In this model we study the morphology of a chemotactic bacterial colony, which grows in the direction of increasing nutrient concentration. Numerical simulations using the level set method and finite difference schemes are presented. The results show rich heterogeneous morphology.

Genetic differentiation and habitat preference of flowering-time variants within Gymnadenia conopsea

Using fast-evolving microsatellites, more slowly evolving ITS markers and performing habitat analyses, we demonstrated a drastic genetic divergence and significant habitat differentiation between early- and late-flowering variants of plants morphologically belonging to Gymnadenia conopsea ssp conopsea. The two phenological variants can either be found in separate or in mixed populations. Information from microsatellite markers and ITS sequences indicated the occurrence of an early historical split between the two flowering-time variants, a split that has been maintained until the present time even within sympatric populations. Early-flowering variants were also far more genetically diverse, had more alleles per microsatellite locus and a wider habitat amplitude than late-flowering variants. As a comparison, we included G. odoratissima in the sequencing study. We found G. odoratissima to be most closely related to the early-flowering type. This indicates a more ancient divergence event between the two flowering-time variants within G. conopsea ssp conopsea than between the two different species G. odoratissima and the early-flowering variant of G. conopsea. Possible explanations to the results arrived at and possible mechanisms maintaining the genetic separation are discussed.

Patterns of genetic variation in Gymnadenia conopsea, the fragrant orchid

Gymnadenia conopsea (L.) R. Br., or the fragrant orchid, is one of many plant species negatively influenced by new practices in agriculture and forestry during the last decades. This study describes the level of microsatellite variation within and among 10 Swedish populations of this species. It was not possible to detect strong effects of small population size or fragmentation. In general, the species had high genetic variation within and low genetic divergence among populations, although the correlation between population size and number of alleles was close to significance at the 95% level. Also, a significant isolation by distance effect was observed, indicating the presence of modest restrictions in gene dispersal between the investigated populations.

Demineralization of the vertebral skeleton in Atlantic salmon Salmo salar L. during spawning migration

In Atlantic salmon, Salmo salar, the mineral rate of vertebrae in a given fish varies according to the position of the vertebra along the rachidian axis. Indeed, the mean rate goes from 49% in the anterior vertebrae and raises to 51% in post-truncal vertebrae. Although no significant difference in the mineral rate was noticed between males and females either in the lower river basin or after spawning, the mineral rate of vertebral bone decreased significantly (1-2%) during spawning migration. Vertebrae, like scales, are an important reservoir of calcium from which fasting salmon draws the minerals and organic materials necessary for the substantial remodeling of cranial bones in males and for sexual maturation. We hypothesize that mineral decrease in vertebrae may be the result of a halastasic demineralization of the vertebral tissues.

13C-urea breath test results in pigs challenged with Helicobacter pylori or other urease producing bacteria

The gastric bacterial flora and its influence on the 13C-urea breath test (UBT) for detection of Helicobacter pylori infection was studied in a pig model. Seven SPF minipigs were used. H. pylori or a mix of other urease positive bacteria were administered orally. UBT, serum and biopsies for histology and culture were collected. Our results show that UBT is not specific for H. pylori in pigs as the gastric bacterial flora is responsible for the high UBT values observed. Furthermore, the Ellegaard Göttingen SPF minipigs are not useful in an animal model for H. pylori studies.

Humoral immune responses to Mycoplasma hyopneumoniae in sows and offspring following an outbreak of mycoplasmosis

Previously healthy sows, seropositive to Mycoplasma hyopneumoniae, developed clinical signs of mycoplasmosis, as well as increasing amounts of antibodies to M. hyopneumoniae during an outbreak of the disease in a herd. During the early phase of the outbreak, young piglets (2 weeks) with maternal antibodies remained healthy while older seronegative piglets (4-7 weeks) developed the disease. The duration of the maternal antibodies to M. hyopneumoniae varied between litters and was related to the amount of antibodies in the serum of the dam. In sows, the level of serum antibodies decreased continuously from 4 weeks ante partum to partus, and the level of antibodies in the whey of colostrum was comparable to that in serum 4 weeks ante partum. After loss of maternal antibodies to M. hyopneumoniae, seropositive animals were not found among piglets younger than 9 weeks. Therefore peripheral blood mononuclear cells (PBMC) were collected from various age categories of piglets in order to measure the ability to produce antibodies to M. hyopneumoniae in vitro. PBMC obtained from piglets aged 1 and 3 weeks produced few antibodies to M. hyopneumoniae. Significantly higher levels of antibodies to M. hyopneumoniae were produced by PBMC obtained from pigs aged 5-9 weeks. Thus, the ability of PBMC to produce antibodies to M. hyopneumoniae in vitro seemed to be age-dependent.

Dihydrotestosterone and testosterone levels in men screened for prostate cancer: a study of a randomized population

OBJECTIVE

To investigate the possible relationship between serum levels of prostate specific antigen (PSA), dihydrotestosterone (DHT), testosterone, sexual-hormone binding globulin (SHBG) and tumour stage, grade and ploidy in 65 cases of prostate cancer diagnosed in a screening study compared to 130 controls from the same population.

PATIENTS, SUBJECTS AND METHODS

From a population of 26,602 men between the ages of 55 and 70 years, 2400 were selected randomly and invited to undergo screening for prostate cancer using a digital rectal examination, transrectal ultrasonography and PSA analysis. Among the 1782 attendees, 65 cases of prostate cancer were diagnosed. Each case was matched with two control subjects of similar age and prostate volume from the screening population. Frozen serum samples were analysed for PSA, DHT, testosterone and SHBG, and compared to the diagnosis and tumour stage, grade and ploidy. Comparisons between these variables, and multivariate and regression analyses were performed.

RESULTS

There were significant differences in PSA level with all variables except tumour ploidy. DHT levels were slightly lower in patients with prostate cancer but the difference was not statistically significant. There was a trend towards lower DHT values in more advanced tumours and the difference for T-stages was close to statistical significance (P = 0.059). Testosterone levels were lower in patients with cancer than in the control group, but the differences were not significant. There was no correlation between testosterone levels, tumour stage and ploidy, but the differences in testosterone level in tumours of a low grade of differentiation compared to those with intermediate and high grade was nearly significant (P = 0.058). The testosterone/DHT ratio tended to be higher in patients with more advanced tumours. SHBG levels were lower in patients with cancer than in controls but the differences were not statistically significant. There were no systematic variations of tumour stage, grade and ploidy. Multivariate analysis showed that if the PSA level was known, then DHT, testosterone or SHBG added no further information concerning diagnosis, stage, grade or ploidy. Regression analysis on T-stage, PSA level and DHT showed an inverse linear relationship between PSA and DHT for stage T-3 (P = 0.035), but there was no relationship between PSA and testosterone.

CONCLUSION

PSA was of value in discriminating between cases and controls and between various tumour stages and grades, but no statistically significant correlation was found for ploidy. If PSA level was known, no other variable added information in individual cases. Within a group, DHT levels tended to be lower among cases and in those with more advanced tumours. There was an inverse relationship between tumour volume, as defined by PSA level, and 5 alpha-reductase activity, as defined by DHT level, and the testosterone/DHT ratio. This trend was most obvious with T-stage. No systematic variation were found in the levels of testosterone or SHBG.

Separate taxation and married women's labor supply: a comparison of West Germany and Sweden

"The focus of this paper is an empirical analysis of the effects of taxation on women's incentives to contribute to family income. Data on earnings and individual characteristics in 1984 for married or cohabiting Swedish couples...are used together with similar data on German couples.... The main features of the personal income taxation of the two countries have been programmed, and are used for simulating after tax incomes using both tax systems for both countries.... The difference between the Swedish and German tax systems is an important factor in explaining why Swedish women participate more than German women in the labor market, although paid parental leaves and subsidized childcare are other important explanations for the Swedish situation."

Effects of diltiazem and metoprolol on blood pressure, adverse symptoms and general well-being. The Swedish Diltiazem-Metoprolol Multi-Centre Study Group

General well-being, adverse effects and anti-hypertensive efficacy have been investigated in a double blind, parallel-group, dose-response multicentre study of diltiazem and metoprolol monotherapy for hypertension. 128 patients with primary hypertension were included from 10 participating centres. The patients were randomized to receive oral diltiazem 120-240-360 mg/day or metoprolol 50-100-200 mg/day. Each dose was given for a 4-week period as a forced titration regime. In all 119 patients, 59 and 60, respectively, on diltiazem and metoprolol completed the study protocol. There were dose-dependent reductions in supine and standing blood pressures (BP) after both diltiazem and metoprolol therapy. In the diltiazem group, supine BP was reduced by 10 (11)/10 (6) mmHg (SBP/DBP) at the highest dose level, and the corresponding values for the metoprolol group were 7 (16)/8 (9) mmHg (SBP/DBP). Target pressures (DBP less than or equal to 90 mmHg and/or a reduction in DBP of greater than or equal to 10%) were reached in 63% and 48% of the patients, respectively. The incidence and severity of dose-dependent adverse effects, as evaluated by spontaneous reports or open and direct questioning, did not differ between treatments. Subjective well-being, evaluated by a self-administered questionnaire, the MSE-profile, did not differ significantly between diltiazem and metoprolol therapy. However, after an initial slight deterioration, contentment and vitality tended to improve with increasing doses of diltiazem, while a dose-related deterioration in these variables was observed on metoprolol therapy. At the highest dose levels, contentment and vitality tended to be better in the diltiazem than the metoprolol group. Thus, diltiazem and metoprolol in daily doses of 120-360 mg and 50-200 mg, respectively, produce comparable and parallel reductions in supine and standing BP. However, while subjective well-being tended to improve with increasing doses of diltiazem, there was a negative trend for metoprolol. It is concluded that diltiazem, given as monotherapy to hypertensive patients, does not impair subjective well-being.

Diltiazem compared with metoprolol as add-on-therapies to diuretics in hypertension. Swedish Diltiazem-Metoprolol Multicentre Study Group

In a randomized, double-blind, parallel group study, diltiazem was compared with metoprolol as add-on therapy to diuretic treatment in 115 patients with hypertension. Following a placebo and diuretic period of four weeks, patients were randomized to either slow release diltiazem 90 mg twice daily or metoprolol 100 mg once daily using a double dummy technique. If after four weeks a target supine diastolic blood pressure (DBP) less than or equal to 90 mmHg pressure was not reached, the doses of diltiazem and metoprolol were doubled. Supine inclusion systolic/diastolic blood pressures (SBP/DBP) at randomization were 158 +/- 13 (mean +/- SD)/102 +/- 5 mmHg in the diltiazem group and 158 +/- 17/101 +/- 6 mmHg in the metoprolol group. Active therapy significantly lowered SBP and DBP in both groups by 7-10%. Heart rate was significantly lowered in both groups, although the effect of metoprolol was more pronounced. Response rates (supine DBP less than or equal to 90 mmHg and/or decreased by greater than or equal to 10%) were 43% on diltiazem 90 mg twice daily and 52% on metoprolol 100 mg once daily, increasing to 82% and 62%, respectively, after dose escalations. No serious side effects were seen, but three patients, two on diltiazem and one on metoprolol, were withdrawn from the study due to severe headache, nausea and bradycardia respectively. of mild to moderate adverse reactions, tiredness was most frequent, occurring in 14.5% and 15.8% on active diltiazem and metoprolol therapy, respectively. We conclude that both diltiazem and metoprolol lower BP when added to diuretics in hypertensive patients.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of diltiazem and metoprolol in hypertension. Swedish Diltiazem-Metoprolol Multicentre Study Group

A double-blind, parallel-group multicentre study has been done to compare the antihypertensive properties, effects on serum lipoproteins and adverse effect profiles of diltiazem and metoprolol given as monotherapy to primary hypertensive patients. 128 patients were included from 10 participating centers. Following a placebo wash-out period of 5 weeks, patients were randomized either to diltiazem or metoprolol treatment according to a forced titration regimen. Each dose was given for a 4-week period in a stepwise regimen. A total of 119 patients, 59 and 60 in the two groups, completed the study. Supine and standing BPs were reduced in a similar, dose-dependent fashion by diltiazem and metoprolol. In the former supine BP fell from 161/101 to 151/91 mmHg at the highest dose level. In the latter patients, supine BP at the highest dose level was reduced from 161/102 to 155/94 mmHg. Target pressures (DBP less than or equal to 90 mmHg and/or DBP reduction of greater than or equal to 10%) were reached in 63% and 48% of the patients, respectively. HDL-cholesterol was increased in diltiazem-treated patients and decreased in those on metoprolol. Otherwise, serum lipoproteins did not differ significantly between treatments. The incidence and severity of dose-dependent adverse effects did not differ significantly between treatments, although moderate to distressing side effects were reported more commonly by metoprolol-treated patients. Ankle oedema and breathlessness tended to be more common on diltiazem therapy, while tiredness, increased sweating and sleep disturbances appeared to be experienced more frequently by metoprolol-treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Cis-trans isomerization of an angiotensin I-converting enzyme inhibitor. An enzyme kinetic and nuclear magnetic resonance study

The angiotensin I-converting enzyme (peptidyl-dipeptide hydrolase, EC 3.4.15.1) inhibitor, ramiprilat (2-[N-[(S)-1-ethoxycarbonyl-3-phenylpropyl]-L-Ala]-(1S,3S,5S)-2- azabicyclo[3.3.0]octane-3-carboxylic acid), is shown to exist in tow conformational isomers, cis and trans, which interconvert around the amide bond. The two conformers were separated by reversed-phase high-performance liquid chromatography. The conformers were identified by nuclear Overhauser effect measurements. From line shape analysis the isomerization rate constants were determined to be kcis----trans = 15 s-1 and ktrans----cis = 5 s-1 at 368 K in [2H]phosphate buffer (p2H 7.5). By enzyme kinetic studies using 3-(2-furylacryloyl)-L-Phe-Gly-Gly as substrate, the trans conformer was found to be the most potent enzyme inhibitor, whereas the cis conformer had a very low inhibitory effect. A new inhibition mechanism is presented for this type of slow, tight-binding inhibitors that contain an amide bond. This mechanism involves an equilibrium between the two conformers and the enzyme-bound inhibitor complex.